includes/libs/rdbms/database/Database.php

   1 <?php
   2 /**
   3  * @defgroup Database Database
   4  *
   5  * This file deals with database interface functions
   6  * and query specifics/optimisations.
   7  *
   8  * This program is free software; you can redistribute it and/or modify
   9  * it under the terms of the GNU General Public License as published by
  10  * the Free Software Foundation; either version 2 of the License, or
  11  * (at your option) any later version.
  12  *
  13  * This program is distributed in the hope that it will be useful,
  14  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  15  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
  16  * GNU General Public License for more details.
  17  *
  18  * You should have received a copy of the GNU General Public License along
  19  * with this program; if not, write to the Free Software Foundation, Inc.,
  20  * 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
  21  * http://www.gnu.org/copyleft/gpl.html
  22  *
  23  * @file
  24  * @ingroup Database
  25  */
  26 namespace Wikimedia\Rdbms;
  27
  28 use Psr\Log\LoggerAwareInterface;
  29 use Psr\Log\LoggerInterface;
  30 use Psr\Log\NullLogger;
  31 use Wikimedia\ScopedCallback;
  32 use Wikimedia\Timestamp\ConvertibleTimestamp;
  33 use Wikimedia;
  34 use BagOStuff;
  35 use HashBagOStuff;
  36 use LogicException;
  37 use InvalidArgumentException;
  38 use UnexpectedValueException;
  39 use Exception;
  40 use RuntimeException;
  41 use Throwable;
  42
  43 /**
  44  * Relational database abstraction object
  45  *
  46  * @ingroup Database
  47  * @since 1.28
  48  */
  49 abstract class Database implements IDatabase, IMaintainableDatabase, LoggerAwareInterface {
  50         /** @var string Server that this instance is currently connected to */
  51         protected $server;
  52         /** @var string User that this instance is currently connected under the name of */
  53         protected $user;
  54         /** @var string Password used to establish the current connection */
  55         protected $password;
  56         /** @var array[] Map of (table => (dbname, schema, prefix) map) */
  57         protected $tableAliases = [];
  58         /** @var string[] Map of (index alias => index) */
  59         protected $indexAliases = [];
  60         /** @var bool Whether this PHP instance is for a CLI script */
  61         protected $cliMode;
  62         /** @var string Agent name for query profiling */
  63         protected $agent;
  64         /** @var int Bitfield of class DBO_* constants */
  65         protected $flags;
  66         /** @var array LoadBalancer tracking information */
  67         protected $lbInfo = [];
  68         /** @var array|bool Variables use for schema element placeholders */
  69         protected $schemaVars = false;
  70         /** @var array Parameters used by initConnection() to establish a connection */
  71         protected $connectionParams = [];
  72         /** @var array SQL variables values to use for all new connections */
  73         protected $connectionVariables = [];
  74         /** @var string Current SQL query delimiter */
  75         protected $delimiter = ';';
  76         /** @var string|bool|null Stashed value of html_errors INI setting */
  77         protected $htmlErrors;
  78         /** @var int Row batch size to use for emulated INSERT SELECT queries */
  79         protected $nonNativeInsertSelectBatchSize = 10000;
  80
  81         /** @var BagOStuff APC cache */
  82         protected $srvCache;
  83         /** @var LoggerInterface */
  84         protected $connLogger;
  85         /** @var LoggerInterface */
  86         protected $queryLogger;
  87         /** @var callable Error logging callback */
  88         protected $errorLogger;
  89         /** @var callable Deprecation logging callback */
  90         protected $deprecationLogger;
  91         /** @var callable|null */
  92         protected $profiler;
  93         /** @var TransactionProfiler */
  94         protected $trxProfiler;
  95         /** @var DatabaseDomain */
  96         protected $currentDomain;
  97         /** @var object|resource|null Database connection */
  98         protected $conn;
  99
 100         /** @var IDatabase|null Lazy handle to the master DB this server replicates from */
 101         private $lazyMasterHandle;
 102
 103         /** @var array Map of (name => 1) for locks obtained via lock() */
 104         protected $sessionNamedLocks = [];
 105         /** @var array Map of (table name => 1) for TEMPORARY tables */
 106         protected $sessionTempTables = [];
 107
 108         /** @var int Whether there is an active transaction (1 or 0) */
 109         protected $trxLevel = 0;
 110         /** @var string Hexidecimal string if a transaction is active or empty string otherwise */
 111         protected $trxShortId = '';
 112         /** @var int Transaction status */
 113         protected $trxStatus = self::STATUS_TRX_NONE;
 114         /** @var Exception|null The last error that caused the status to become STATUS_TRX_ERROR */
 115         protected $trxStatusCause;
 116         /** @var array|null Error details of the last statement-only rollback */
 117         private $trxStatusIgnoredCause;
 118         /** @var float|null UNIX timestamp at the time of BEGIN for the last transaction */
 119         private $trxTimestamp = null;
 120         /** @var float Replication lag estimate at the time of BEGIN for the last transaction */
 121         private $trxReplicaLag = null;
 122         /** @var string Name of the function that start the last transaction */
 123         private $trxFname = null;
 124         /** @var bool Whether possible write queries were done in the last transaction started */
 125         private $trxDoneWrites = false;
 126         /** @var bool Whether the current transaction was started implicitly due to DBO_TRX */
 127         private $trxAutomatic = false;
 128         /** @var int Counter for atomic savepoint identifiers (reset with each transaction) */
 129         private $trxAtomicCounter = 0;
 130         /** @var array List of (name, unique ID, savepoint ID) for each active atomic section level */
 131         private $trxAtomicLevels = [];
 132         /** @var bool Whether the current transaction was started implicitly by startAtomic() */
 133         private $trxAutomaticAtomic = false;
 134         /** @var string[] Write query callers of the current transaction */
 135         private $trxWriteCallers = [];
 136         /** @var float Seconds spent in write queries for the current transaction */
 137         private $trxWriteDuration = 0.0;
 138         /** @var int Number of write queries for the current transaction */
 139         private $trxWriteQueryCount = 0;
 140         /** @var int Number of rows affected by write queries for the current transaction */
 141         private $trxWriteAffectedRows = 0;
 142         /** @var float Like trxWriteQueryCount but excludes lock-bound, easy to replicate, queries */
 143         private $trxWriteAdjDuration = 0.0;
 144         /** @var int Number of write queries counted in trxWriteAdjDuration */
 145         private $trxWriteAdjQueryCount = 0;
 146         /** @var array[] List of (callable, method name, atomic section id) */
 147         private $trxIdleCallbacks = [];
 148         /** @var array[] List of (callable, method name, atomic section id) */
 149         private $trxPreCommitCallbacks = [];
 150         /** @var array[] List of (callable, method name, atomic section id) */
 151         private $trxEndCallbacks = [];
 152         /** @var array[] List of (callable, method name, atomic section id) */
 153         private $trxSectionCancelCallbacks = [];
 154         /** @var callable[] Map of (name => callable) */
 155         private $trxRecurringCallbacks = [];
 156         /** @var bool Whether to suppress triggering of transaction end callbacks */
 157         private $trxEndCallbacksSuppressed = false;
 158
 159         /** @var int[] Prior flags member variable values */
 160         private $priorFlags = [];
 161
 162         /** @var integer|null Rows affected by the last query to query() or its CRUD wrappers */
 163         protected $affectedRowCount;
 164
 165         /** @var float UNIX timestamp */
 166         private $lastPing = 0.0;
 167         /** @var string The last SQL query attempted */
 168         private $lastQuery = '';
 169         /** @var float|bool UNIX timestamp of last write query */
 170         private $lastWriteTime = false;
 171         /** @var string|bool */
 172         private $lastPhpError = false;
 173         /** @var float Query rount trip time estimate */
 174         private $lastRoundTripEstimate = 0.0;
 175
 176         /** @var string Lock granularity is on the level of the entire database */
 177         const ATTR_DB_LEVEL_LOCKING = 'db-level-locking';
 178         /** @var string The SCHEMA keyword refers to a grouping of tables in a database */
 179         const ATTR_SCHEMAS_AS_TABLE_GROUPS = 'supports-schemas';
 180
 181         /** @var int New Database instance will not be connected yet when returned */
 182         const NEW_UNCONNECTED = 0;
 183         /** @var int New Database instance will already be connected when returned */
 184         const NEW_CONNECTED = 1;
 185
 186         /** @var int Transaction is in a error state requiring a full or savepoint rollback */
 187         const STATUS_TRX_ERROR = 1;
 188         /** @var int Transaction is active and in a normal state */
 189         const STATUS_TRX_OK = 2;
 190         /** @var int No transaction is active */
 191         const STATUS_TRX_NONE = 3;
 192
 193         /** @var string Idiom used when a cancelable atomic section started the transaction */
 194         private static $NOT_APPLICABLE = 'n/a';
 195         /** @var string Prefix to the atomic section counter used to make savepoint IDs */
 196         private static $SAVEPOINT_PREFIX = 'wikimedia_rdbms_atomic';
 197
 198         /** @var int Writes to this temporary table do not affect lastDoneWrites() */
 199         private static $TEMP_NORMAL = 1;
 200         /** @var int Writes to this temporary table effect lastDoneWrites() */
 201         private static $TEMP_PSEUDO_PERMANENT = 2;
 202
 203         /** Number of times to re-try an operation in case of deadlock */
 204         private static $DEADLOCK_TRIES = 4;
 205         /** Minimum time to wait before retry, in microseconds */
 206         private static $DEADLOCK_DELAY_MIN = 500000;
 207         /** Maximum time to wait before retry */
 208         private static $DEADLOCK_DELAY_MAX = 1500000;
 209
 210         /** How long before it is worth doing a dummy query to test the connection */
 211         private static $PING_TTL = 1.0;
 212         private static $PING_QUERY = 'SELECT 1 AS ping';
 213
 214         private static $TINY_WRITE_SEC = 0.010;
 215         private static $SLOW_WRITE_SEC = 0.500;
 216         private static $SMALL_WRITE_ROWS = 100;
 217
 218         /**
 219          * @note exceptions for missing libraries/drivers should be thrown in initConnection()
 220          * @param array $params Parameters passed from Database::factory()
 221          */
 222         protected function __construct( array $params ) {
 223                 foreach ( [ 'host', 'user', 'password', 'dbname', 'schema', 'tablePrefix' ] as $name ) {
 224                         $this->connectionParams[$name] = $params[$name];
 225                 }
 226
 227                 $this->cliMode = $params['cliMode'];
 228                 // Agent name is added to SQL queries in a comment, so make sure it can't break out
 229                 $this->agent = str_replace( '/', '-', $params['agent'] );
 230
 231                 $this->flags = $params['flags'];
 232                 if ( $this->flags & self::DBO_DEFAULT ) {
 233                         if ( $this->cliMode ) {
 234                                 $this->flags &= ~self::DBO_TRX;
 235                         } else {
 236                                 $this->flags |= self::DBO_TRX;
 237                         }
 238                 }
 239                 // Disregard deprecated DBO_IGNORE flag (T189999)
 240                 $this->flags &= ~self::DBO_IGNORE;
 241
 242                 $this->connectionVariables = $params['variables'];
 243
 244                 $this->srvCache = $params['srvCache'] ?? new HashBagOStuff();
 245
 246                 $this->profiler = is_callable( $params['profiler'] ) ? $params['profiler'] : null;
 247                 $this->trxProfiler = $params['trxProfiler'];
 248                 $this->connLogger = $params['connLogger'];
 249                 $this->queryLogger = $params['queryLogger'];
 250                 $this->errorLogger = $params['errorLogger'];
 251                 $this->deprecationLogger = $params['deprecationLogger'];
 252
 253                 if ( isset( $params['nonNativeInsertSelectBatchSize'] ) ) {
 254                         $this->nonNativeInsertSelectBatchSize = $params['nonNativeInsertSelectBatchSize'];
 255                 }
 256
 257                 // Set initial dummy domain until open() sets the final DB/prefix
 258                 $this->currentDomain = new DatabaseDomain(
 259                         $params['dbname'] != '' ? $params['dbname'] : null,
 260                         $params['schema'] != '' ? $params['schema'] : null,
 261                         $params['tablePrefix']
 262                 );
 263         }
 264
 265         /**
 266          * Initialize the connection to the database over the wire (or to local files)
 267          *
 268          * @throws LogicException
 269          * @throws InvalidArgumentException
 270          * @throws DBConnectionError
 271          * @since 1.31
 272          */
 273         final public function initConnection() {
 274                 if ( $this->isOpen() ) {
 275                         throw new LogicException( __METHOD__ . ': already connected.' );
 276                 }
 277                 // Establish the connection
 278                 $this->doInitConnection();
 279         }
 280
 281         /**
 282          * Actually connect to the database over the wire (or to local files)
 283          *
 284          * @throws InvalidArgumentException
 285          * @throws DBConnectionError
 286          * @since 1.31
 287          */
 288         protected function doInitConnection() {
 289                 if ( strlen( $this->connectionParams['user'] ) ) {
 290                         $this->open(
 291                                 $this->connectionParams['host'],
 292                                 $this->connectionParams['user'],
 293                                 $this->connectionParams['password'],
 294                                 $this->connectionParams['dbname'],
 295                                 $this->connectionParams['schema'],
 296                                 $this->connectionParams['tablePrefix']
 297                         );
 298                 } else {
 299                         throw new InvalidArgumentException( "No database user provided." );
 300                 }
 301         }
 302
 303         /**
 304          * Open a new connection to the database (closing any existing one)
 305          *
 306          * @param string $server Database server host
 307          * @param string $user Database user name
 308          * @param string $password Database user password
 309          * @param string $dbName Database name
 310          * @param string|null $schema Database schema name
 311          * @param string $tablePrefix Table prefix
 312          * @throws DBConnectionError
 313          */
 314         abstract protected function open( $server, $user, $password, $dbName, $schema, $tablePrefix );
 315
 316         /**
 317          * Construct a Database subclass instance given a database type and parameters
 318          *
 319          * This also connects to the database immediately upon object construction
 320          *
 321          * @param string $dbType A possible DB type (sqlite, mysql, postgres,...)
 322          * @param array $p Parameter map with keys:
 323          *   - host : The hostname of the DB server
 324          *   - user : The name of the database user the client operates under
 325          *   - password : The password for the database user
 326          *   - dbname : The name of the database to use where queries do not specify one.
 327          *      The database must exist or an error might be thrown. Setting this to the empty string
 328          *      will avoid any such errors and make the handle have no implicit database scope. This is
 329          *      useful for queries like SHOW STATUS, CREATE DATABASE, or DROP DATABASE. Note that a
 330          *      "database" in Postgres is rougly equivalent to an entire MySQL server. This the domain
 331          *      in which user names and such are defined, e.g. users are database-specific in Postgres.
 332          *   - schema : The database schema to use (if supported). A "schema" in Postgres is roughly
 333          *      equivalent to a "database" in MySQL. Note that MySQL and SQLite do not use schemas.
 334          *   - tablePrefix : Optional table prefix that is implicitly added on to all table names
 335          *      recognized in queries. This can be used in place of schemas for handle site farms.
 336          *   - flags : Optional bitfield of DBO_* constants that define connection, protocol,
 337          *      buffering, and transaction behavior. It is STRONGLY adviced to leave the DBO_DEFAULT
 338          *      flag in place UNLESS this this database simply acts as a key/value store.
 339          *   - driver: Optional name of a specific DB client driver. For MySQL, there is only the
 340          *      'mysqli' driver; the old one 'mysql' has been removed.
 341          *   - variables: Optional map of session variables to set after connecting. This can be
 342          *      used to adjust lock timeouts or encoding modes and the like.
 343          *   - connLogger: Optional PSR-3 logger interface instance.
 344          *   - queryLogger: Optional PSR-3 logger interface instance.
 345          *   - profiler : Optional callback that takes a section name argument and returns
 346          *      a ScopedCallback instance that ends the profile section in its destructor.
 347          *      These will be called in query(), using a simplified version of the SQL that
 348          *      also includes the agent as a SQL comment.
 349          *   - trxProfiler: Optional TransactionProfiler instance.
 350          *   - errorLogger: Optional callback that takes an Exception and logs it.
 351          *   - deprecationLogger: Optional callback that takes a string and logs it.
 352          *   - cliMode: Whether to consider the execution context that of a CLI script.
 353          *   - agent: Optional name used to identify the end-user in query profiling/logging.
 354          *   - srvCache: Optional BagOStuff instance to an APC-style cache.
 355          *   - nonNativeInsertSelectBatchSize: Optional batch size for non-native INSERT SELECT emulation.
 356          * @param int $connect One of the class constants (NEW_CONNECTED, NEW_UNCONNECTED) [optional]
 357          * @return Database|null If the database driver or extension cannot be found
 358          * @throws InvalidArgumentException If the database driver or extension cannot be found
 359          * @since 1.18
 360          */
 361         final public static function factory( $dbType, $p = [], $connect = self::NEW_CONNECTED ) {
 362                 $class = self::getClass( $dbType, $p['driver'] ?? null );
 363
 364                 if ( class_exists( $class ) && is_subclass_of( $class, IDatabase::class ) ) {
 365                         // Resolve some defaults for b/c
 366                         $p['host'] = $p['host'] ?? false;
 367                         $p['user'] = $p['user'] ?? false;
 368                         $p['password'] = $p['password'] ?? false;
 369                         $p['dbname'] = $p['dbname'] ?? false;
 370                         $p['flags'] = $p['flags'] ?? 0;
 371                         $p['variables'] = $p['variables'] ?? [];
 372                         $p['tablePrefix'] = $p['tablePrefix'] ?? '';
 373                         $p['schema'] = $p['schema'] ?? null;
 374                         $p['cliMode'] = $p['cliMode'] ?? ( PHP_SAPI === 'cli' || PHP_SAPI === 'phpdbg' );
 375                         $p['agent'] = $p['agent'] ?? '';
 376                         if ( !isset( $p['connLogger'] ) ) {
 377                                 $p['connLogger'] = new NullLogger();
 378                         }
 379                         if ( !isset( $p['queryLogger'] ) ) {
 380                                 $p['queryLogger'] = new NullLogger();
 381                         }
 382                         $p['profiler'] = $p['profiler'] ?? null;
 383                         if ( !isset( $p['trxProfiler'] ) ) {
 384                                 $p['trxProfiler'] = new TransactionProfiler();
 385                         }
 386                         if ( !isset( $p['errorLogger'] ) ) {
 387                                 $p['errorLogger'] = function ( Exception $e ) {
 388                                         trigger_error( get_class( $e ) . ': ' . $e->getMessage(), E_USER_WARNING );
 389                                 };
 390                         }
 391                         if ( !isset( $p['deprecationLogger'] ) ) {
 392                                 $p['deprecationLogger'] = function ( $msg ) {
 393                                         trigger_error( $msg, E_USER_DEPRECATED );
 394                                 };
 395                         }
 396
 397                         /** @var Database $conn */
 398                         $conn = new $class( $p );
 399                         if ( $connect == self::NEW_CONNECTED ) {
 400                                 $conn->initConnection();
 401                         }
 402                 } else {
 403                         $conn = null;
 404                 }
 405
 406                 return $conn;
 407         }
 408
 409         /**
 410          * @param string $dbType A possible DB type (sqlite, mysql, postgres,...)
 411          * @param string|null $driver Optional name of a specific DB client driver
 412          * @return array Map of (Database::ATTR_* constant => value) for all such constants
 413          * @throws InvalidArgumentException
 414          * @since 1.31
 415          */
 416         final public static function attributesFromType( $dbType, $driver = null ) {
 417                 static $defaults = [
 418                         self::ATTR_DB_LEVEL_LOCKING => false,
 419                         self::ATTR_SCHEMAS_AS_TABLE_GROUPS => false
 420                 ];
 421
 422                 $class = self::getClass( $dbType, $driver );
 423
 424                 return call_user_func( [ $class, 'getAttributes' ] ) + $defaults;
 425         }
 426
 427         /**
 428          * @param string $dbType A possible DB type (sqlite, mysql, postgres,...)
 429          * @param string|null $driver Optional name of a specific DB client driver
 430          * @return string Database subclass name to use
 431          * @throws InvalidArgumentException
 432          */
 433         private static function getClass( $dbType, $driver = null ) {
 434                 // For database types with built-in support, the below maps type to IDatabase
 435                 // implementations. For types with multipe driver implementations (PHP extensions),
 436                 // an array can be used, keyed by extension name. In case of an array, the
 437                 // optional 'driver' parameter can be used to force a specific driver. Otherwise,
 438                 // we auto-detect the first available driver. For types without built-in support,
 439                 // an class named "Database<Type>" us used, eg. DatabaseFoo for type 'foo'.
 440                 static $builtinTypes = [
 441                         'mssql' => DatabaseMssql::class,
 442                         'mysql' => [ 'mysqli' => DatabaseMysqli::class ],
 443                         'sqlite' => DatabaseSqlite::class,
 444                         'postgres' => DatabasePostgres::class,
 445                 ];
 446
 447                 $dbType = strtolower( $dbType );
 448                 $class = false;
 449
 450                 if ( isset( $builtinTypes[$dbType] ) ) {
 451                         $possibleDrivers = $builtinTypes[$dbType];
 452                         if ( is_string( $possibleDrivers ) ) {
 453                                 $class = $possibleDrivers;
 454                         } elseif ( (string)$driver !== '' ) {
 455                                 if ( !isset( $possibleDrivers[$driver] ) ) {
 456                                         throw new InvalidArgumentException( __METHOD__ .
 457                                                 " type '$dbType' does not support driver '{$driver}'" );
 458                                 }
 459
 460                                 $class = $possibleDrivers[$driver];
 461                         } else {
 462                                 foreach ( $possibleDrivers as $posDriver => $possibleClass ) {
 463                                         if ( extension_loaded( $posDriver ) ) {
 464                                                 $class = $possibleClass;
 465                                                 break;
 466                                         }
 467                                 }
 468                         }
 469                 } else {
 470                         $class = 'Database' . ucfirst( $dbType );
 471                 }
 472
 473                 if ( $class === false ) {
 474                         throw new InvalidArgumentException( __METHOD__ .
 475                                 " no viable database extension found for type '$dbType'" );
 476                 }
 477
 478                 return $class;
 479         }
 480
 481         /**
 482          * @return array Map of (Database::ATTR_* constant => value
 483          * @since 1.31
 484          */
 485         protected static function getAttributes() {
 486                 return [];
 487         }
 488
 489         /**
 490          * Set the PSR-3 logger interface to use for query logging. (The logger
 491          * interfaces for connection logging and error logging can be set with the
 492          * constructor.)
 493          *
 494          * @param LoggerInterface $logger
 495          */
 496         public function setLogger( LoggerInterface $logger ) {
 497                 $this->queryLogger = $logger;
 498         }
 499
 500         public function getServerInfo() {
 501                 return $this->getServerVersion();
 502         }
 503
 504         public function bufferResults( $buffer = null ) {
 505                 $res = !$this->getFlag( self::DBO_NOBUFFER );
 506                 if ( $buffer !== null ) {
 507                         $buffer
 508                                 ? $this->clearFlag( self::DBO_NOBUFFER )
 509                                 : $this->setFlag( self::DBO_NOBUFFER );
 510                 }
 511
 512                 return $res;
 513         }
 514
 515         public function trxLevel() {
 516                 return $this->trxLevel;
 517         }
 518
 519         public function trxTimestamp() {
 520                 return $this->trxLevel ? $this->trxTimestamp : null;
 521         }
 522
 523         /**
 524          * @return int One of the STATUS_TRX_* class constants
 525          * @since 1.31
 526          */
 527         public function trxStatus() {
 528                 return $this->trxStatus;
 529         }
 530
 531         public function tablePrefix( $prefix = null ) {
 532                 $old = $this->currentDomain->getTablePrefix();
 533                 if ( $prefix !== null ) {
 534                         $this->currentDomain = new DatabaseDomain(
 535                                 $this->currentDomain->getDatabase(),
 536                                 $this->currentDomain->getSchema(),
 537                                 $prefix
 538                         );
 539                 }
 540
 541                 return $old;
 542         }
 543
 544         public function dbSchema( $schema = null ) {
 545                 if ( strlen( $schema ) && $this->getDBname() === null ) {
 546                         throw new DBUnexpectedError( $this, "Cannot set schema to '$schema'; no database set." );
 547                 }
 548
 549                 $old = $this->currentDomain->getSchema();
 550                 if ( $schema !== null ) {
 551                         $this->currentDomain = new DatabaseDomain(
 552                                 $this->currentDomain->getDatabase(),
 553                                 // DatabaseDomain uses null for unspecified schemas
 554                                 strlen( $schema ) ? $schema : null,
 555                                 $this->currentDomain->getTablePrefix()
 556                         );
 557                 }
 558
 559                 return (string)$old;
 560         }
 561
 562         /**
 563          * @return string Schema to use to qualify relations in queries
 564          */
 565         protected function relationSchemaQualifier() {
 566                 return $this->dbSchema();
 567         }
 568
 569         public function getLBInfo( $name = null ) {
 570                 if ( is_null( $name ) ) {
 571                         return $this->lbInfo;
 572                 }
 573
 574                 if ( array_key_exists( $name, $this->lbInfo ) ) {
 575                         return $this->lbInfo[$name];
 576                 }
 577
 578                 return null;
 579         }
 580
 581         public function setLBInfo( $name, $value = null ) {
 582                 if ( is_null( $value ) ) {
 583                         $this->lbInfo = $name;
 584                 } else {
 585                         $this->lbInfo[$name] = $value;
 586                 }
 587         }
 588
 589         public function setLazyMasterHandle( IDatabase $conn ) {
 590                 $this->lazyMasterHandle = $conn;
 591         }
 592
 593         /**
 594          * @return IDatabase|null
 595          * @see setLazyMasterHandle()
 596          * @since 1.27
 597          */
 598         protected function getLazyMasterHandle() {
 599                 return $this->lazyMasterHandle;
 600         }
 601
 602         public function implicitGroupby() {
 603                 return true;
 604         }
 605
 606         public function implicitOrderby() {
 607                 return true;
 608         }
 609
 610         public function lastQuery() {
 611                 return $this->lastQuery;
 612         }
 613
 614         public function doneWrites() {
 615                 return (bool)$this->lastWriteTime;
 616         }
 617
 618         public function lastDoneWrites() {
 619                 return $this->lastWriteTime ?: false;
 620         }
 621
 622         public function writesPending() {
 623                 return $this->trxLevel && $this->trxDoneWrites;
 624         }
 625
 626         public function writesOrCallbacksPending() {
 627                 return $this->trxLevel && (
 628                         $this->trxDoneWrites ||
 629                         $this->trxIdleCallbacks ||
 630                         $this->trxPreCommitCallbacks ||
 631                         $this->trxEndCallbacks ||
 632                         $this->trxSectionCancelCallbacks
 633                 );
 634         }
 635
 636         public function preCommitCallbacksPending() {
 637                 return $this->trxLevel && $this->trxPreCommitCallbacks;
 638         }
 639
 640         /**
 641          * @return string|null
 642          */
 643         final protected function getTransactionRoundId() {
 644                 // If transaction round participation is enabled, see if one is active
 645                 if ( $this->getFlag( self::DBO_TRX ) ) {
 646                         $id = $this->getLBInfo( 'trxRoundId' );
 647
 648                         return is_string( $id ) ? $id : null;
 649                 }
 650
 651                 return null;
 652         }
 653
 654         public function pendingWriteQueryDuration( $type = self::ESTIMATE_TOTAL ) {
 655                 if ( !$this->trxLevel ) {
 656                         return false;
 657                 } elseif ( !$this->trxDoneWrites ) {
 658                         return 0.0;
 659                 }
 660
 661                 switch ( $type ) {
 662                         case self::ESTIMATE_DB_APPLY:
 663                                 return $this->pingAndCalculateLastTrxApplyTime();
 664                         default: // everything
 665                                 return $this->trxWriteDuration;
 666                 }
 667         }
 668
 669         /**
 670          * @return float Time to apply writes to replicas based on trxWrite* fields
 671          */
 672         private function pingAndCalculateLastTrxApplyTime() {
 673                 $this->ping( $rtt );
 674
 675                 $rttAdjTotal = $this->trxWriteAdjQueryCount * $rtt;
 676                 $applyTime = max( $this->trxWriteAdjDuration - $rttAdjTotal, 0 );
 677                 // For omitted queries, make them count as something at least
 678                 $omitted = $this->trxWriteQueryCount - $this->trxWriteAdjQueryCount;
 679                 $applyTime += self::$TINY_WRITE_SEC * $omitted;
 680
 681                 return $applyTime;
 682         }
 683
 684         public function pendingWriteCallers() {
 685                 return $this->trxLevel ? $this->trxWriteCallers : [];
 686         }
 687
 688         public function pendingWriteRowsAffected() {
 689                 return $this->trxWriteAffectedRows;
 690         }
 691
 692         /**
 693          * List the methods that have write queries or callbacks for the current transaction
 694          *
 695          * This method should not be used outside of Database/LoadBalancer
 696          *
 697          * @return string[]
 698          * @since 1.32
 699          */
 700         public function pendingWriteAndCallbackCallers() {
 701                 $fnames = $this->pendingWriteCallers();
 702                 foreach ( [
 703                         $this->trxIdleCallbacks,
 704                         $this->trxPreCommitCallbacks,
 705                         $this->trxEndCallbacks,
 706                         $this->trxSectionCancelCallbacks
 707                 ] as $callbacks ) {
 708                         foreach ( $callbacks as $callback ) {
 709                                 $fnames[] = $callback[1];
 710                         }
 711                 }
 712
 713                 return $fnames;
 714         }
 715
 716         /**
 717          * @return string
 718          */
 719         private function flatAtomicSectionList() {
 720                 return array_reduce( $this->trxAtomicLevels, function ( $accum, $v ) {
 721                         return $accum === null ? $v[0] : "$accum, " . $v[0];
 722                 } );
 723         }
 724
 725         public function isOpen() {
 726                 return (bool)$this->conn;
 727         }
 728
 729         public function setFlag( $flag, $remember = self::REMEMBER_NOTHING ) {
 730                 if ( ( $flag & self::DBO_IGNORE ) ) {
 731                         throw new UnexpectedValueException( "Modifying DBO_IGNORE is not allowed." );
 732                 }
 733
 734                 if ( $remember === self::REMEMBER_PRIOR ) {
 735                         array_push( $this->priorFlags, $this->flags );
 736                 }
 737                 $this->flags |= $flag;
 738         }
 739
 740         public function clearFlag( $flag, $remember = self::REMEMBER_NOTHING ) {
 741                 if ( ( $flag & self::DBO_IGNORE ) ) {
 742                         throw new UnexpectedValueException( "Modifying DBO_IGNORE is not allowed." );
 743                 }
 744
 745                 if ( $remember === self::REMEMBER_PRIOR ) {
 746                         array_push( $this->priorFlags, $this->flags );
 747                 }
 748                 $this->flags &= ~$flag;
 749         }
 750
 751         public function restoreFlags( $state = self::RESTORE_PRIOR ) {
 752                 if ( !$this->priorFlags ) {
 753                         return;
 754                 }
 755
 756                 if ( $state === self::RESTORE_INITIAL ) {
 757                         $this->flags = reset( $this->priorFlags );
 758                         $this->priorFlags = [];
 759                 } else {
 760                         $this->flags = array_pop( $this->priorFlags );
 761                 }
 762         }
 763
 764         public function getFlag( $flag ) {
 765                 return (bool)( $this->flags & $flag );
 766         }
 767
 768         /**
 769          * @param string $name Class field name
 770          * @return mixed
 771          * @deprecated Since 1.28
 772          */
 773         public function getProperty( $name ) {
 774                 return $this->$name;
 775         }
 776
 777         public function getDomainID() {
 778                 return $this->currentDomain->getId();
 779         }
 780
 781         final public function getWikiID() {
 782                 return $this->getDomainID();
 783         }
 784
 785         /**
 786          * Get information about an index into an object
 787          * @param string $table Table name
 788          * @param string $index Index name
 789          * @param string $fname Calling function name
 790          * @return mixed Database-specific index description class or false if the index does not exist
 791          */
 792         abstract function indexInfo( $table, $index, $fname = __METHOD__ );
 793
 794         /**
 795          * Wrapper for addslashes()
 796          *
 797          * @param string $s String to be slashed.
 798          * @return string Slashed string.
 799          */
 800         abstract function strencode( $s );
 801
 802         /**
 803          * Set a custom error handler for logging errors during database connection
 804          */
 805         protected function installErrorHandler() {
 806                 $this->lastPhpError = false;
 807                 $this->htmlErrors = ini_set( 'html_errors', '0' );
 808                 set_error_handler( [ $this, 'connectionErrorLogger' ] );
 809         }
 810
 811         /**
 812          * Restore the previous error handler and return the last PHP error for this DB
 813          *
 814          * @return bool|string
 815          */
 816         protected function restoreErrorHandler() {
 817                 restore_error_handler();
 818                 if ( $this->htmlErrors !== false ) {
 819                         ini_set( 'html_errors', $this->htmlErrors );
 820                 }
 821
 822                 return $this->getLastPHPError();
 823         }
 824
 825         /**
 826          * @return string|bool Last PHP error for this DB (typically connection errors)
 827          */
 828         protected function getLastPHPError() {
 829                 if ( $this->lastPhpError ) {
 830                         $error = preg_replace( '!\[<a.*</a>\]!', '', $this->lastPhpError );
 831                         $error = preg_replace( '!^.*?:\s?(.*)$!', '$1', $error );
 832
 833                         return $error;
 834                 }
 835
 836                 return false;
 837         }
 838
 839         /**
 840          * Error handler for logging errors during database connection
 841          * This method should not be used outside of Database classes
 842          *
 843          * @param int $errno
 844          * @param string $errstr
 845          */
 846         public function connectionErrorLogger( $errno, $errstr ) {
 847                 $this->lastPhpError = $errstr;
 848         }
 849
 850         /**
 851          * Create a log context to pass to PSR-3 logger functions.
 852          *
 853          * @param array $extras Additional data to add to context
 854          * @return array
 855          */
 856         protected function getLogContext( array $extras = [] ) {
 857                 return array_merge(
 858                         [
 859                                 'db_server' => $this->server,
 860                                 'db_name' => $this->getDBname(),
 861                                 'db_user' => $this->user,
 862                         ],
 863                         $extras
 864                 );
 865         }
 866
 867         final public function close() {
 868                 $exception = null; // error to throw after disconnecting
 869
 870                 $wasOpen = (bool)$this->conn;
 871                 // This should mostly do nothing if the connection is already closed
 872                 if ( $this->conn ) {
 873                         // Roll back any dangling transaction first
 874                         if ( $this->trxLevel ) {
 875                                 if ( $this->trxAtomicLevels ) {
 876                                         // Cannot let incomplete atomic sections be committed
 877                                         $levels = $this->flatAtomicSectionList();
 878                                         $exception = new DBUnexpectedError(
 879                                                 $this,
 880                                                 __METHOD__ . ": atomic sections $levels are still open."
 881                                         );
 882                                 } elseif ( $this->trxAutomatic ) {
 883                                         // Only the connection manager can commit non-empty DBO_TRX transactions
 884                                         // (empty ones we can silently roll back)
 885                                         if ( $this->writesOrCallbacksPending() ) {
 886                                                 $exception = new DBUnexpectedError(
 887                                                         $this,
 888                                                         __METHOD__ .
 889                                                         ": mass commit/rollback of peer transaction required (DBO_TRX set)."
 890                                                 );
 891                                         }
 892                                 } else {
 893                                         // Manual transactions should have been committed or rolled
 894                                         // back, even if empty.
 895                                         $exception = new DBUnexpectedError(
 896                                                 $this,
 897                                                 __METHOD__ . ": transaction is still open (from {$this->trxFname})."
 898                                         );
 899                                 }
 900
 901                                 if ( $this->trxEndCallbacksSuppressed ) {
 902                                         $exception = $exception ?: new DBUnexpectedError(
 903                                                 $this,
 904                                                 __METHOD__ . ': callbacks are suppressed; cannot properly commit.'
 905                                         );
 906                                 }
 907
 908                                 // Rollback the changes and run any callbacks as needed
 909                                 $this->rollback( __METHOD__, self::FLUSHING_INTERNAL );
 910                         }
 911
 912                         // Close the actual connection in the binding handle
 913                         $closed = $this->closeConnection();
 914                 } else {
 915                         $closed = true; // already closed; nothing to do
 916                 }
 917
 918                 $this->conn = false;
 919
 920                 // Throw any unexpected errors after having disconnected
 921                 if ( $exception instanceof Exception ) {
 922                         throw $exception;
 923                 }
 924
 925                 // Note that various subclasses call close() at the start of open(), which itself is
 926                 // called by replaceLostConnection(). In that case, just because onTransactionResolution()
 927                 // callbacks are pending does not mean that an exception should be thrown. Rather, they
 928                 // will be executed after the reconnection step.
 929                 if ( $wasOpen ) {
 930                         // Sanity check that no callbacks are dangling
 931                         $fnames = $this->pendingWriteAndCallbackCallers();
 932                         if ( $fnames ) {
 933                                 throw new RuntimeException(
 934                                         "Transaction callbacks are still pending:\n" . implode( ', ', $fnames )
 935                                 );
 936                         }
 937                 }
 938
 939                 return $closed;
 940         }
 941
 942         /**
 943          * Make sure there is an open connection handle (alive or not) as a sanity check
 944          *
 945          * This guards against fatal errors to the binding handle not being defined
 946          * in cases where open() was never called or close() was already called
 947          *
 948          * @throws DBUnexpectedError
 949          */
 950         final protected function assertHasConnectionHandle() {
 951                 if ( !$this->isOpen() ) {
 952                         throw new DBUnexpectedError( $this, "DB connection was already closed." );
 953                 }
 954         }
 955
 956         /**
 957          * Make sure that this server is not marked as a replica nor read-only as a sanity check
 958          *
 959          * @throws DBReadOnlyRoleError
 960          * @throws DBReadOnlyError
 961          */
 962         protected function assertIsWritableMaster() {
 963                 if ( $this->getLBInfo( 'replica' ) === true ) {
 964                         throw new DBReadOnlyRoleError(
 965                                 $this,
 966                                 'Write operations are not allowed on replica database connections.'
 967                         );
 968                 }
 969                 $reason = $this->getReadOnlyReason();
 970                 if ( $reason !== false ) {
 971                         throw new DBReadOnlyError( $this, "Database is read-only: $reason" );
 972                 }
 973         }
 974
 975         /**
 976          * Closes underlying database connection
 977          * @since 1.20
 978          * @return bool Whether connection was closed successfully
 979          */
 980         abstract protected function closeConnection();
 981
 982         /**
 983          * Run a query and return a DBMS-dependent wrapper or boolean
 984          *
 985          * This is meant to handle the basic command of actually sending a query to the
 986          * server via the driver. No implicit transaction, reconnection, nor retry logic
 987          * should happen here. The higher level query() method is designed to handle those
 988          * sorts of concerns. This method should not trigger such higher level methods.
 989          *
 990          * The lastError() and lastErrno() methods should meaningfully reflect what error,
 991          * if any, occured during the last call to this method. Methods like executeQuery(),
 992          * query(), select(), insert(), update(), delete(), and upsert() implement their calls
 993          * to doQuery() such that an immediately subsequent call to lastError()/lastErrno()
 994          * meaningfully reflects any error that occured during that public query method call.
 995          *
 996          * For SELECT queries, this returns either:
 997          *   - a) A driver-specific value/resource, only on success. This can be iterated
 998          *        over by calling fetchObject()/fetchRow() until there are no more rows.
 999          *        Alternatively, the result can be passed to resultObject() to obtain a
1000          *        ResultWrapper instance which can then be iterated over via "foreach".
1001          *   - b) False, on any query failure
1002          *
1003          * For non-SELECT queries, this returns either:
1004          *   - a) A driver-specific value/resource, only on success
1005          *   - b) True, only on success (e.g. no meaningful result other than "OK")
1006          *   - c) False, on any query failure
1007          *
1008          * @param string $sql SQL query
1009          * @return mixed|bool An object, resource, or true on success; false on failure
1010          */
1011         abstract protected function doQuery( $sql );
1012
1013         /**
1014          * Determine whether a query writes to the DB. When in doubt, this returns true.
1015          *
1016          * Main use cases:
1017          *
1018          * - Subsequent web requests should not need to wait for replication from
1019          *   the master position seen by this web request, unless this request made
1020          *   changes to the master. This is handled by ChronologyProtector by checking
1021          *   doneWrites() at the end of the request. doneWrites() returns true if any
1022          *   query set lastWriteTime; which query() does based on isWriteQuery().
1023          *
1024          * - Reject write queries to replica DBs, in query().
1025          *
1026          * @param string $sql
1027          * @return bool
1028          */
1029         protected function isWriteQuery( $sql ) {
1030                 // BEGIN and COMMIT queries are considered read queries here.
1031                 // Database backends and drivers (MySQL, MariaDB, php-mysqli) generally
1032                 // treat these as write queries, in that their results have "affected rows"
1033                 // as meta data as from writes, instead of "num rows" as from reads.
1034                 // But, we treat them as read queries because when reading data (from
1035                 // either replica or master) we use transactions to enable repeatable-read
1036                 // snapshots, which ensures we get consistent results from the same snapshot
1037                 // for all queries within a request. Use cases:
1038                 // - Treating these as writes would trigger ChronologyProtector (see method doc).
1039                 // - We use this method to reject writes to replicas, but we need to allow
1040                 //   use of transactions on replicas for read snapshots. This is fine given
1041                 //   that transactions by themselves don't make changes, only actual writes
1042                 //   within the transaction matter, which we still detect.
1043                 return !preg_match(
1044                         '/^(?:SELECT|BEGIN|ROLLBACK|COMMIT|SAVEPOINT|RELEASE|SET|SHOW|EXPLAIN|USE|\(SELECT)\b/i',
1045                         $sql
1046                 );
1047         }
1048
1049         /**
1050          * @param string $sql
1051          * @return string|null
1052          */
1053         protected function getQueryVerb( $sql ) {
1054                 return preg_match( '/^\s*([a-z]+)/i', $sql, $m ) ? strtoupper( $m[1] ) : null;
1055         }
1056
1057         /**
1058          * Determine whether a SQL statement is sensitive to isolation level.
1059          *
1060          * A SQL statement is considered transactable if its result could vary
1061          * depending on the transaction isolation level. Operational commands
1062          * such as 'SET' and 'SHOW' are not considered to be transactable.
1063          *
1064          * Main purpose: Used by query() to decide whether to begin a transaction
1065          * before the current query (in DBO_TRX mode, on by default).
1066          *
1067          * @param string $sql
1068          * @return bool
1069          */
1070         protected function isTransactableQuery( $sql ) {
1071                 return !in_array(
1072                         $this->getQueryVerb( $sql ),
1073                         [ 'BEGIN', 'ROLLBACK', 'COMMIT', 'SET', 'SHOW', 'CREATE', 'ALTER', 'USE' ],
1074                         true
1075                 );
1076         }
1077
1078         /**
1079          * @param string $sql A SQL query
1080          * @param bool $pseudoPermanent Treat any table from CREATE TEMPORARY as pseudo-permanent
1081          * @return int|null A self::TEMP_* constant for temp table operations or null otherwise
1082          */
1083         protected function registerTempTableWrite( $sql, $pseudoPermanent ) {
1084                 static $qt = '[`"\']?(\w+)[`"\']?'; // quoted table
1085
1086                 if ( preg_match(
1087                         '/^CREATE\s+TEMPORARY\s+TABLE\s+(?:IF\s+NOT\s+EXISTS\s+)?' . $qt . '/i',
1088                         $sql,
1089                         $matches
1090                 ) ) {
1091                         $type = $pseudoPermanent ? self::$TEMP_PSEUDO_PERMANENT : self::$TEMP_NORMAL;
1092                         $this->sessionTempTables[$matches[1]] = $type;
1093
1094                         return $type;
1095                 } elseif ( preg_match(
1096                         '/^DROP\s+(?:TEMPORARY\s+)?TABLE\s+(?:IF\s+EXISTS\s+)?' . $qt . '/i',
1097                         $sql,
1098                         $matches
1099                 ) ) {
1100                         $type = $this->sessionTempTables[$matches[1]] ?? null;
1101                         unset( $this->sessionTempTables[$matches[1]] );
1102
1103                         return $type;
1104                 } elseif ( preg_match(
1105                         '/^TRUNCATE\s+(?:TEMPORARY\s+)?TABLE\s+(?:IF\s+EXISTS\s+)?' . $qt . '/i',
1106                         $sql,
1107                         $matches
1108                 ) ) {
1109                         return $this->sessionTempTables[$matches[1]] ?? null;
1110                 } elseif ( preg_match(
1111                         '/^(?:(?:INSERT|REPLACE)\s+(?:\w+\s+)?INTO|UPDATE|DELETE\s+FROM)\s+' . $qt . '/i',
1112                         $sql,
1113                         $matches
1114                 ) ) {
1115                         return $this->sessionTempTables[$matches[1]] ?? null;
1116                 }
1117
1118                 return null;
1119         }
1120
1121         public function query( $sql, $fname = __METHOD__, $flags = 0 ) {
1122                 $flags = (int)$flags; // b/c; this field used to be a bool
1123                 // Sanity check that the SQL query is appropriate in the current context and is
1124                 // allowed for an outside caller (e.g. does not break transaction/session tracking).
1125                 $this->assertQueryIsCurrentlyAllowed( $sql, $fname );
1126
1127                 // Send the query to the server and fetch any corresponding errors
1128                 list( $ret, $err, $errno, $unignorable ) = $this->executeQuery( $sql, $fname, $flags );
1129                 if ( $ret === false ) {
1130                         $ignoreErrors = $this->hasFlags( $flags, self::QUERY_SILENCE_ERRORS );
1131                         // Throw an error unless both the ignore flag was set and a rollback is not needed
1132                         $this->reportQueryError( $err, $errno, $sql, $fname, $ignoreErrors && !$unignorable );
1133                 }
1134
1135                 return $this->resultObject( $ret );
1136         }
1137
1138         /**
1139          * Execute a query, retrying it if there is a recoverable connection loss
1140          *
1141          * This is similar to query() except:
1142          *   - It does not prevent all non-ROLLBACK queries if there is a corrupted transaction
1143          *   - It does not disallow raw queries that are supposed to use dedicated IDatabase methods
1144          *   - It does not throw exceptions for common error cases
1145          *
1146          * This is meant for internal use with Database subclasses.
1147          *
1148          * @param string $sql Original SQL query
1149          * @param string $fname Name of the calling function
1150          * @param int $flags Bitfield of class QUERY_* constants
1151          * @return array An n-tuple of:
1152          *   - mixed|bool: An object, resource, or true on success; false on failure
1153          *   - string: The result of calling lastError()
1154          *   - int: The result of calling lastErrno()
1155          *   - bool: Whether a rollback is needed to allow future non-rollback queries
1156          * @throws DBUnexpectedError
1157          */
1158         final protected function executeQuery( $sql, $fname, $flags ) {
1159                 $this->assertHasConnectionHandle();
1160
1161                 $priorTransaction = $this->trxLevel;
1162
1163                 if ( $this->isWriteQuery( $sql ) ) {
1164                         # In theory, non-persistent writes are allowed in read-only mode, but due to things
1165                         # like https://bugs.mysql.com/bug.php?id=33669 that might not work anyway...
1166                         $this->assertIsWritableMaster();
1167                         # Do not treat temporary table writes as "meaningful writes" since they are only
1168                         # visible to one session and are not permanent. Profile them as reads. Integration
1169                         # tests can override this behavior via $flags.
1170                         $pseudoPermanent = $this->hasFlags( $flags, self::QUERY_PSEUDO_PERMANENT );
1171                         $tableType = $this->registerTempTableWrite( $sql, $pseudoPermanent );
1172                         $isPermWrite = ( $tableType !== self::$TEMP_NORMAL );
1173                         # DBConnRef uses QUERY_REPLICA_ROLE to enforce the replica role for raw SQL queries
1174                         if ( $isPermWrite && $this->hasFlags( $flags, self::QUERY_REPLICA_ROLE ) ) {
1175                                 throw new DBReadOnlyRoleError( $this, "Cannot write; target role is DB_REPLICA" );
1176                         }
1177                 } else {
1178                         $isPermWrite = false;
1179                 }
1180
1181                 // Add trace comment to the begin of the sql string, right after the operator.
1182                 // Or, for one-word queries (like "BEGIN" or COMMIT") add it to the end (T44598)
1183                 $commentedSql = preg_replace( '/\s|$/', " /* $fname {$this->agent} */ ", $sql, 1 );
1184
1185                 // Send the query to the server and fetch any corresponding errors
1186                 list( $ret, $err, $errno, $recoverableSR, $recoverableCL, $reconnected ) =
1187                         $this->executeQueryAttempt( $sql, $commentedSql, $isPermWrite, $fname, $flags );
1188
1189                 // Check if the query failed due to a recoverable connection loss
1190                 $allowRetry = !$this->hasFlags( $flags, self::QUERY_NO_RETRY );
1191                 if ( $ret === false && $recoverableCL && $reconnected && $allowRetry ) {
1192                         // Silently resend the query to the server since it is safe and possible
1193                         list( $ret, $err, $errno, $recoverableSR, $recoverableCL ) =
1194                                 $this->executeQueryAttempt( $sql, $commentedSql, $isPermWrite, $fname, $flags );
1195                 }
1196
1197                 $corruptedTrx = false;
1198
1199                 if ( $ret === false ) {
1200                         if ( $priorTransaction ) {
1201                                 if ( $recoverableSR ) {
1202                                         # We're ignoring an error that caused just the current query to be aborted.
1203                                         # But log the cause so we can log a deprecation notice if a caller actually
1204                                         # does ignore it.
1205                                         $this->trxStatusIgnoredCause = [ $err, $errno, $fname ];
1206                                 } elseif ( !$recoverableCL ) {
1207                                         # Either the query was aborted or all queries after BEGIN where aborted.
1208                                         # In the first case, the only options going forward are (a) ROLLBACK, or
1209                                         # (b) ROLLBACK TO SAVEPOINT (if one was set). If the later case, the only
1210                                         # option is ROLLBACK, since the snapshots would have been released.
1211                                         $corruptedTrx = true; // cannot recover
1212                                         $this->trxStatus = self::STATUS_TRX_ERROR;
1213                                         $this->trxStatusCause =
1214                                                 $this->getQueryExceptionAndLog( $err, $errno, $sql, $fname );
1215                                         $this->trxStatusIgnoredCause = null;
1216                                 }
1217                         }
1218                 }
1219
1220                 return [ $ret, $err, $errno, $corruptedTrx ];
1221         }
1222
1223         /**
1224          * Wrapper for doQuery() that handles DBO_TRX, profiling, logging, affected row count
1225          * tracking, and reconnects (without retry) on query failure due to connection loss
1226          *
1227          * @param string $sql Original SQL query
1228          * @param string $commentedSql SQL query with debugging/trace comment
1229          * @param bool $isPermWrite Whether the query is a (non-temporary table) write
1230          * @param string $fname Name of the calling function
1231          * @param int $flags Bitfield of class QUERY_* constants
1232          * @return array An n-tuple of:
1233          *   - mixed|bool: An object, resource, or true on success; false on failure
1234          *   - string: The result of calling lastError()
1235          *   - int: The result of calling lastErrno()
1236          *       - bool: Whether a statement rollback error occured
1237          *   - bool: Whether a disconnect *both* happened *and* was recoverable
1238          *   - bool: Whether a reconnection attempt was *both* made *and* succeeded
1239          * @throws DBUnexpectedError
1240          */
1241         private function executeQueryAttempt( $sql, $commentedSql, $isPermWrite, $fname, $flags ) {
1242                 $priorWritesPending = $this->writesOrCallbacksPending();
1243
1244                 if ( ( $flags & self::QUERY_IGNORE_DBO_TRX ) == 0 ) {
1245                         $this->beginIfImplied( $sql, $fname );
1246                 }
1247
1248                 // Keep track of whether the transaction has write queries pending
1249                 if ( $isPermWrite ) {
1250                         $this->lastWriteTime = microtime( true );
1251                         if ( $this->trxLevel && !$this->trxDoneWrites ) {
1252                                 $this->trxDoneWrites = true;
1253                                 $this->trxProfiler->transactionWritingIn(
1254                                         $this->server, $this->getDomainID(), $this->trxShortId );
1255                         }
1256                 }
1257
1258                 $prefix = !is_null( $this->getLBInfo( 'master' ) ) ? 'query-m: ' : 'query: ';
1259                 $generalizedSql = new GeneralizedSql( $sql, $this->trxShortId, $prefix );
1260
1261                 $startTime = microtime( true );
1262                 $ps = $this->profiler
1263                         ? ( $this->profiler )( $generalizedSql->stringify() )
1264                         : null;
1265                 $this->affectedRowCount = null;
1266                 $this->lastQuery = $sql;
1267                 $ret = $this->doQuery( $commentedSql );
1268                 $lastError = $this->lastError();
1269                 $lastErrno = $this->lastErrno();
1270
1271                 $this->affectedRowCount = $this->affectedRows();
1272                 unset( $ps ); // profile out (if set)
1273                 $queryRuntime = max( microtime( true ) - $startTime, 0.0 );
1274
1275                 $recoverableSR = false; // recoverable statement rollback?
1276                 $recoverableCL = false; // recoverable connection loss?
1277                 $reconnected = false; // reconnection both attempted and succeeded?
1278
1279                 if ( $ret !== false ) {
1280                         $this->lastPing = $startTime;
1281                         if ( $isPermWrite && $this->trxLevel ) {
1282                                 $this->updateTrxWriteQueryTime( $sql, $queryRuntime, $this->affectedRows() );
1283                                 $this->trxWriteCallers[] = $fname;
1284                         }
1285                 } elseif ( $this->wasConnectionError( $lastErrno ) ) {
1286                         # Check if no meaningful session state was lost
1287                         $recoverableCL = $this->canRecoverFromDisconnect( $sql, $priorWritesPending );
1288                         # Update session state tracking and try to restore the connection
1289                         $reconnected = $this->replaceLostConnection( __METHOD__ );
1290                 } else {
1291                         # Check if only the last query was rolled back
1292                         $recoverableSR = $this->wasKnownStatementRollbackError();
1293                 }
1294
1295                 if ( $sql === self::$PING_QUERY ) {
1296                         $this->lastRoundTripEstimate = $queryRuntime;
1297                 }
1298
1299                 $this->trxProfiler->recordQueryCompletion(
1300                         $generalizedSql,
1301                         $startTime,
1302                         $isPermWrite,
1303                         $isPermWrite ? $this->affectedRows() : $this->numRows( $ret )
1304                 );
1305
1306                 // Avoid the overhead of logging calls unless debug mode is enabled
1307                 if ( $this->getFlag( self::DBO_DEBUG ) ) {
1308                         $this->queryLogger->debug(
1309                                 "{method} [{runtime}s]: $sql",
1310                                 [
1311                                         'method' => $fname,
1312                                         'db_host' => $this->getServer(),
1313                                         'domain' => $this->getDomainID(),
1314                                         'runtime' => round( $queryRuntime, 3 )
1315                                 ]
1316                         );
1317                 }
1318
1319                 return [ $ret, $lastError, $lastErrno, $recoverableSR, $recoverableCL, $reconnected ];
1320         }
1321
1322         /**
1323          * Start an implicit transaction if DBO_TRX is enabled and no transaction is active
1324          *
1325          * @param string $sql
1326          * @param string $fname
1327          */
1328         private function beginIfImplied( $sql, $fname ) {
1329                 if (
1330                         !$this->trxLevel &&
1331                         $this->getFlag( self::DBO_TRX ) &&
1332                         $this->isTransactableQuery( $sql )
1333                 ) {
1334                         $this->begin( __METHOD__ . " ($fname)", self::TRANSACTION_INTERNAL );
1335                         $this->trxAutomatic = true;
1336                 }
1337         }
1338
1339         /**
1340          * Update the estimated run-time of a query, not counting large row lock times
1341          *
1342          * LoadBalancer can be set to rollback transactions that will create huge replication
1343          * lag. It bases this estimate off of pendingWriteQueryDuration(). Certain simple
1344          * queries, like inserting a row can take a long time due to row locking. This method
1345          * uses some simple heuristics to discount those cases.
1346          *
1347          * @param string $sql A SQL write query
1348          * @param float $runtime Total runtime, including RTT
1349          * @param int $affected Affected row count
1350          */
1351         private function updateTrxWriteQueryTime( $sql, $runtime, $affected ) {
1352                 // Whether this is indicative of replica DB runtime (except for RBR or ws_repl)
1353                 $indicativeOfReplicaRuntime = true;
1354                 if ( $runtime > self::$SLOW_WRITE_SEC ) {
1355                         $verb = $this->getQueryVerb( $sql );
1356                         // insert(), upsert(), replace() are fast unless bulky in size or blocked on locks
1357                         if ( $verb === 'INSERT' ) {
1358                                 $indicativeOfReplicaRuntime = $this->affectedRows() > self::$SMALL_WRITE_ROWS;
1359                         } elseif ( $verb === 'REPLACE' ) {
1360                                 $indicativeOfReplicaRuntime = $this->affectedRows() > self::$SMALL_WRITE_ROWS / 2;
1361                         }
1362                 }
1363
1364                 $this->trxWriteDuration += $runtime;
1365                 $this->trxWriteQueryCount += 1;
1366                 $this->trxWriteAffectedRows += $affected;
1367                 if ( $indicativeOfReplicaRuntime ) {
1368                         $this->trxWriteAdjDuration += $runtime;
1369                         $this->trxWriteAdjQueryCount += 1;
1370                 }
1371         }
1372
1373         /**
1374          * Error out if the DB is not in a valid state for a query via query()
1375          *
1376          * @param string $sql
1377          * @param string $fname
1378          * @throws DBTransactionStateError
1379          */
1380         private function assertQueryIsCurrentlyAllowed( $sql, $fname ) {
1381                 $verb = $this->getQueryVerb( $sql );
1382                 if ( $verb === 'USE' ) {
1383                         throw new DBUnexpectedError( $this, "Got USE query; use selectDomain() instead." );
1384                 }
1385
1386                 if ( $verb === 'ROLLBACK' ) { // transaction/savepoint
1387                         return;
1388                 }
1389
1390                 if ( $this->trxStatus < self::STATUS_TRX_OK ) {
1391                         throw new DBTransactionStateError(
1392                                 $this,
1393                                 "Cannot execute query from $fname while transaction status is ERROR.",
1394                                 [],
1395                                 $this->trxStatusCause
1396                         );
1397                 } elseif ( $this->trxStatus === self::STATUS_TRX_OK && $this->trxStatusIgnoredCause ) {
1398                         list( $iLastError, $iLastErrno, $iFname ) = $this->trxStatusIgnoredCause;
1399                         call_user_func( $this->deprecationLogger,
1400                                 "Caller from $fname ignored an error originally raised from $iFname: " .
1401                                 "[$iLastErrno] $iLastError"
1402                         );
1403                         $this->trxStatusIgnoredCause = null;
1404                 }
1405         }
1406
1407         public function assertNoOpenTransactions() {
1408                 if ( $this->explicitTrxActive() ) {
1409                         throw new DBTransactionError(
1410                                 $this,
1411                                 "Explicit transaction still active. A caller may have caught an error. "
1412                                 . "Open transactions: " . $this->flatAtomicSectionList()
1413                         );
1414                 }
1415         }
1416
1417         /**
1418          * Determine whether it is safe to retry queries after a database connection is lost
1419          *
1420          * @param string $sql SQL query
1421          * @param bool $priorWritesPending Whether there is a transaction open with
1422          *     possible write queries or transaction pre-commit/idle callbacks
1423          *     waiting on it to finish.
1424          * @return bool True if it is safe to retry the query, false otherwise
1425          */
1426         private function canRecoverFromDisconnect( $sql, $priorWritesPending ) {
1427                 # Transaction dropped; this can mean lost writes, or REPEATABLE-READ snapshots.
1428                 # Dropped connections also mean that named locks are automatically released.
1429                 # Only allow error suppression in autocommit mode or when the lost transaction
1430                 # didn't matter anyway (aside from DBO_TRX snapshot loss).
1431                 if ( $this->sessionNamedLocks ) {
1432                         return false; // possible critical section violation
1433                 } elseif ( $this->sessionTempTables ) {
1434                         return false; // tables might be queried latter
1435                 } elseif ( $sql === 'COMMIT' ) {
1436                         return !$priorWritesPending; // nothing written anyway? (T127428)
1437                 } elseif ( $sql === 'ROLLBACK' ) {
1438                         return true; // transaction lost...which is also what was requested :)
1439                 } elseif ( $this->explicitTrxActive() ) {
1440                         return false; // don't drop atomocity and explicit snapshots
1441                 } elseif ( $priorWritesPending ) {
1442                         return false; // prior writes lost from implicit transaction
1443                 }
1444
1445                 return true;
1446         }
1447
1448         /**
1449          * Clean things up after session (and thus transaction) loss before reconnect
1450          */
1451         private function handleSessionLossPreconnect() {
1452                 // Clean up tracking of session-level things...
1453                 // https://dev.mysql.com/doc/refman/5.7/en/implicit-commit.html
1454                 // https://www.postgresql.org/docs/9.2/static/sql-createtable.html (ignoring ON COMMIT)
1455                 $this->sessionTempTables = [];
1456                 // https://dev.mysql.com/doc/refman/5.7/en/miscellaneous-functions.html#function_get-lock
1457                 // https://www.postgresql.org/docs/9.4/static/functions-admin.html#FUNCTIONS-ADVISORY-LOCKS
1458                 $this->sessionNamedLocks = [];
1459                 // Session loss implies transaction loss
1460                 $this->trxLevel = 0;
1461                 $this->trxAtomicCounter = 0;
1462                 $this->trxIdleCallbacks = []; // T67263; transaction already lost
1463                 $this->trxPreCommitCallbacks = []; // T67263; transaction already lost
1464                 // @note: leave trxRecurringCallbacks in place
1465                 if ( $this->trxDoneWrites ) {
1466                         $this->trxProfiler->transactionWritingOut(
1467                                 $this->server,
1468                                 $this->getDomainID(),
1469                                 $this->trxShortId,
1470                                 $this->pendingWriteQueryDuration( self::ESTIMATE_TOTAL ),
1471                                 $this->trxWriteAffectedRows
1472                         );
1473                 }
1474         }
1475
1476         /**
1477          * Clean things up after session (and thus transaction) loss after reconnect
1478          */
1479         private function handleSessionLossPostconnect() {
1480                 try {
1481                         // Handle callbacks in trxEndCallbacks, e.g. onTransactionResolution().
1482                         // If callback suppression is set then the array will remain unhandled.
1483                         $this->runOnTransactionIdleCallbacks( self::TRIGGER_ROLLBACK );
1484                 } catch ( Exception $ex ) {
1485                         // Already logged; move on...
1486                 }
1487                 try {
1488                         // Handle callbacks in trxRecurringCallbacks, e.g. setTransactionListener()
1489                         $this->runTransactionListenerCallbacks( self::TRIGGER_ROLLBACK );
1490                 } catch ( Exception $ex ) {
1491                         // Already logged; move on...
1492                 }
1493         }
1494
1495         /**
1496          * Checks whether the cause of the error is detected to be a timeout.
1497          *
1498          * It returns false by default, and not all engines support detecting this yet.
1499          * If this returns false, it will be treated as a generic query error.
1500          *
1501          * @param string $error Error text
1502          * @param int $errno Error number
1503          * @return bool
1504          */
1505         protected function wasQueryTimeout( $error, $errno ) {
1506                 return false;
1507         }
1508
1509         /**
1510          * Report a query error. Log the error, and if neither the object ignore
1511          * flag nor the $ignoreErrors flag is set, throw a DBQueryError.
1512          *
1513          * @param string $error
1514          * @param int $errno
1515          * @param string $sql
1516          * @param string $fname
1517          * @param bool $ignore
1518          * @throws DBQueryError
1519          */
1520         public function reportQueryError( $error, $errno, $sql, $fname, $ignore = false ) {
1521                 if ( $ignore ) {
1522                         $this->queryLogger->debug( "SQL ERROR (ignored): $error\n" );
1523                 } else {
1524                         $exception = $this->getQueryExceptionAndLog( $error, $errno, $sql, $fname );
1525
1526                         throw $exception;
1527                 }
1528         }
1529
1530         /**
1531          * @param string $error
1532          * @param string|int $errno
1533          * @param string $sql
1534          * @param string $fname
1535          * @return DBError
1536          */
1537         private function getQueryExceptionAndLog( $error, $errno, $sql, $fname ) {
1538                 $sql1line = mb_substr( str_replace( "\n", "\\n", $sql ), 0, 5 * 1024 );
1539                 $this->queryLogger->error(
1540                         "{fname}\t{db_server}\t{errno}\t{error}\t{sql1line}",
1541                         $this->getLogContext( [
1542                                 'method' => __METHOD__,
1543                                 'errno' => $errno,
1544                                 'error' => $error,
1545                                 'sql1line' => $sql1line,
1546                                 'fname' => $fname,
1547                                 'trace' => ( new RuntimeException() )->getTraceAsString()
1548                         ] )
1549                 );
1550                 $this->queryLogger->debug( "SQL ERROR: " . $error . "\n" );
1551                 if ( $this->wasQueryTimeout( $error, $errno ) ) {
1552                         $e = new DBQueryTimeoutError( $this, $error, $errno, $sql, $fname );
1553                 } elseif ( $this->wasConnectionError( $errno ) ) {
1554                         $e = new DBQueryDisconnectedError( $this, $error, $errno, $sql, $fname );
1555                 } else {
1556                         $e = new DBQueryError( $this, $error, $errno, $sql, $fname );
1557                 }
1558
1559                 return $e;
1560         }
1561
1562         public function freeResult( $res ) {
1563         }
1564
1565         public function selectField(
1566                 $table, $var, $cond = '', $fname = __METHOD__, $options = [], $join_conds = []
1567         ) {
1568                 if ( $var === '*' ) { // sanity
1569                         throw new DBUnexpectedError( $this, "Cannot use a * field: got '$var'" );
1570                 }
1571
1572                 if ( !is_array( $options ) ) {
1573                         $options = [ $options ];
1574                 }
1575
1576                 $options['LIMIT'] = 1;
1577
1578                 $res = $this->select( $table, $var, $cond, $fname, $options, $join_conds );
1579                 if ( $res === false ) {
1580                         throw new DBUnexpectedError( $this, "Got false from select()" );
1581                 }
1582
1583                 $row = $this->fetchRow( $res );
1584                 if ( $row === false ) {
1585                         return false;
1586                 }
1587
1588                 return reset( $row );
1589         }
1590
1591         public function selectFieldValues(
1592                 $table, $var, $cond = '', $fname = __METHOD__, $options = [], $join_conds = []
1593         ) {
1594                 if ( $var === '*' ) { // sanity
1595                         throw new DBUnexpectedError( $this, "Cannot use a * field" );
1596                 } elseif ( !is_string( $var ) ) { // sanity
1597                         throw new DBUnexpectedError( $this, "Cannot use an array of fields" );
1598                 }
1599
1600                 if ( !is_array( $options ) ) {
1601                         $options = [ $options ];
1602                 }
1603
1604                 $res = $this->select( $table, [ 'value' => $var ], $cond, $fname, $options, $join_conds );
1605                 if ( $res === false ) {
1606                         throw new DBUnexpectedError( $this, "Got false from select()" );
1607                 }
1608
1609                 $values = [];
1610                 foreach ( $res as $row ) {
1611                         $values[] = $row->value;
1612                 }
1613
1614                 return $values;
1615         }
1616
1617         /**
1618          * Returns an optional USE INDEX clause to go after the table, and a
1619          * string to go at the end of the query.
1620          *
1621          * @param array $options Associative array of options to be turned into
1622          *   an SQL query, valid keys are listed in the function.
1623          * @return array
1624          * @see Database::select()
1625          */
1626         protected function makeSelectOptions( $options ) {
1627                 $preLimitTail = $postLimitTail = '';
1628                 $startOpts = '';
1629
1630                 $noKeyOptions = [];
1631
1632                 foreach ( $options as $key => $option ) {
1633                         if ( is_numeric( $key ) ) {
1634                                 $noKeyOptions[$option] = true;
1635                         }
1636                 }
1637
1638                 $preLimitTail .= $this->makeGroupByWithHaving( $options );
1639
1640                 $preLimitTail .= $this->makeOrderBy( $options );
1641
1642                 if ( isset( $noKeyOptions['FOR UPDATE'] ) ) {
1643                         $postLimitTail .= ' FOR UPDATE';
1644                 }
1645
1646                 if ( isset( $noKeyOptions['LOCK IN SHARE MODE'] ) ) {
1647                         $postLimitTail .= ' LOCK IN SHARE MODE';
1648                 }
1649
1650                 if ( isset( $noKeyOptions['DISTINCT'] ) || isset( $noKeyOptions['DISTINCTROW'] ) ) {
1651                         $startOpts .= 'DISTINCT';
1652                 }
1653
1654                 # Various MySQL extensions
1655                 if ( isset( $noKeyOptions['STRAIGHT_JOIN'] ) ) {
1656                         $startOpts .= ' /*! STRAIGHT_JOIN */';
1657                 }
1658
1659                 if ( isset( $noKeyOptions['HIGH_PRIORITY'] ) ) {
1660                         $startOpts .= ' HIGH_PRIORITY';
1661                 }
1662
1663                 if ( isset( $noKeyOptions['SQL_BIG_RESULT'] ) ) {
1664                         $startOpts .= ' SQL_BIG_RESULT';
1665                 }
1666
1667                 if ( isset( $noKeyOptions['SQL_BUFFER_RESULT'] ) ) {
1668                         $startOpts .= ' SQL_BUFFER_RESULT';
1669                 }
1670
1671                 if ( isset( $noKeyOptions['SQL_SMALL_RESULT'] ) ) {
1672                         $startOpts .= ' SQL_SMALL_RESULT';
1673                 }
1674
1675                 if ( isset( $noKeyOptions['SQL_CALC_FOUND_ROWS'] ) ) {
1676                         $startOpts .= ' SQL_CALC_FOUND_ROWS';
1677                 }
1678
1679                 if ( isset( $noKeyOptions['SQL_CACHE'] ) ) {
1680                         $startOpts .= ' SQL_CACHE';
1681                 }
1682
1683                 if ( isset( $noKeyOptions['SQL_NO_CACHE'] ) ) {
1684                         $startOpts .= ' SQL_NO_CACHE';
1685                 }
1686
1687                 if ( isset( $options['USE INDEX'] ) && is_string( $options['USE INDEX'] ) ) {
1688                         $useIndex = $this->useIndexClause( $options['USE INDEX'] );
1689                 } else {
1690                         $useIndex = '';
1691                 }
1692                 if ( isset( $options['IGNORE INDEX'] ) && is_string( $options['IGNORE INDEX'] ) ) {
1693                         $ignoreIndex = $this->ignoreIndexClause( $options['IGNORE INDEX'] );
1694                 } else {
1695                         $ignoreIndex = '';
1696                 }
1697
1698                 return [ $startOpts, $useIndex, $preLimitTail, $postLimitTail, $ignoreIndex ];
1699         }
1700
1701         /**
1702          * Returns an optional GROUP BY with an optional HAVING
1703          *
1704          * @param array $options Associative array of options
1705          * @return string
1706          * @see Database::select()
1707          * @since 1.21
1708          */
1709         protected function makeGroupByWithHaving( $options ) {
1710                 $sql = '';
1711                 if ( isset( $options['GROUP BY'] ) ) {
1712                         $gb = is_array( $options['GROUP BY'] )
1713                                 ? implode( ',', $options['GROUP BY'] )
1714                                 : $options['GROUP BY'];
1715                         $sql .= ' GROUP BY ' . $gb;
1716                 }
1717                 if ( isset( $options['HAVING'] ) ) {
1718                         $having = is_array( $options['HAVING'] )
1719                                 ? $this->makeList( $options['HAVING'], self::LIST_AND )
1720                                 : $options['HAVING'];
1721                         $sql .= ' HAVING ' . $having;
1722                 }
1723
1724                 return $sql;
1725         }
1726
1727         /**
1728          * Returns an optional ORDER BY
1729          *
1730          * @param array $options Associative array of options
1731          * @return string
1732          * @see Database::select()
1733          * @since 1.21
1734          */
1735         protected function makeOrderBy( $options ) {
1736                 if ( isset( $options['ORDER BY'] ) ) {
1737                         $ob = is_array( $options['ORDER BY'] )
1738                                 ? implode( ',', $options['ORDER BY'] )
1739                                 : $options['ORDER BY'];
1740
1741                         return ' ORDER BY ' . $ob;
1742                 }
1743
1744                 return '';
1745         }
1746
1747         public function select(
1748                 $table, $vars, $conds = '', $fname = __METHOD__, $options = [], $join_conds = []
1749         ) {
1750                 $sql = $this->selectSQLText( $table, $vars, $conds, $fname, $options, $join_conds );
1751
1752                 return $this->query( $sql, $fname );
1753         }
1754
1755         public function selectSQLText( $table, $vars, $conds = '', $fname = __METHOD__,
1756                 $options = [], $join_conds = []
1757         ) {
1758                 if ( is_array( $vars ) ) {
1759                         $fields = implode( ',', $this->fieldNamesWithAlias( $vars ) );
1760                 } else {
1761                         $fields = $vars;
1762                 }
1763
1764                 $options = (array)$options;
1765                 $useIndexes = ( isset( $options['USE INDEX'] ) && is_array( $options['USE INDEX'] ) )
1766                         ? $options['USE INDEX']
1767                         : [];
1768                 $ignoreIndexes = (
1769                         isset( $options['IGNORE INDEX'] ) &&
1770                         is_array( $options['IGNORE INDEX'] )
1771                 )
1772                         ? $options['IGNORE INDEX']
1773                         : [];
1774
1775                 if (
1776                         $this->selectOptionsIncludeLocking( $options ) &&
1777                         $this->selectFieldsOrOptionsAggregate( $vars, $options )
1778                 ) {
1779                         // Some DB types (postgres/oracle) disallow FOR UPDATE with aggregate
1780                         // functions. Discourage use of such queries to encourage compatibility.
1781                         call_user_func(
1782                                 $this->deprecationLogger,
1783                                 __METHOD__ . ": aggregation used with a locking SELECT ($fname)."
1784                         );
1785                 }
1786
1787                 if ( is_array( $table ) ) {
1788                         $from = ' FROM ' .
1789                                 $this->tableNamesWithIndexClauseOrJOIN(
1790                                         $table, $useIndexes, $ignoreIndexes, $join_conds );
1791                 } elseif ( $table != '' ) {
1792                         $from = ' FROM ' .
1793                                 $this->tableNamesWithIndexClauseOrJOIN(
1794                                         [ $table ], $useIndexes, $ignoreIndexes, [] );
1795                 } else {
1796                         $from = '';
1797                 }
1798
1799                 list( $startOpts, $useIndex, $preLimitTail, $postLimitTail, $ignoreIndex ) =
1800                         $this->makeSelectOptions( $options );
1801
1802                 if ( is_array( $conds ) ) {
1803                         $conds = $this->makeList( $conds, self::LIST_AND );
1804                 }
1805
1806                 if ( $conds === null || $conds === false ) {
1807                         $this->queryLogger->warning(
1808                                 __METHOD__
1809                                 . ' called from '
1810                                 . $fname
1811                                 . ' with incorrect parameters: $conds must be a string or an array'
1812                         );
1813                         $conds = '';
1814                 }
1815
1816                 if ( $conds === '' || $conds === '*' ) {
1817                         $sql = "SELECT $startOpts $fields $from $useIndex $ignoreIndex $preLimitTail";
1818                 } elseif ( is_string( $conds ) ) {
1819                         $sql = "SELECT $startOpts $fields $from $useIndex $ignoreIndex " .
1820                                 "WHERE $conds $preLimitTail";
1821                 } else {
1822                         throw new DBUnexpectedError( $this, __METHOD__ . ' called with incorrect parameters' );
1823                 }
1824
1825                 if ( isset( $options['LIMIT'] ) ) {
1826                         $sql = $this->limitResult( $sql, $options['LIMIT'],
1827                                 $options['OFFSET'] ?? false );
1828                 }
1829                 $sql = "$sql $postLimitTail";
1830
1831                 if ( isset( $options['EXPLAIN'] ) ) {
1832                         $sql = 'EXPLAIN ' . $sql;
1833                 }
1834
1835                 return $sql;
1836         }
1837
1838         public function selectRow( $table, $vars, $conds, $fname = __METHOD__,
1839                 $options = [], $join_conds = []
1840         ) {
1841                 $options = (array)$options;
1842                 $options['LIMIT'] = 1;
1843
1844                 $res = $this->select( $table, $vars, $conds, $fname, $options, $join_conds );
1845                 if ( $res === false ) {
1846                         throw new DBUnexpectedError( $this, "Got false from select()" );
1847                 }
1848
1849                 if ( !$this->numRows( $res ) ) {
1850                         return false;
1851                 }
1852
1853                 return $this->fetchObject( $res );
1854         }
1855
1856         public function estimateRowCount(
1857                 $table, $var = '*', $conds = '', $fname = __METHOD__, $options = [], $join_conds = []
1858         ) {
1859                 $conds = $this->normalizeConditions( $conds, $fname );
1860                 $column = $this->extractSingleFieldFromList( $var );
1861                 if ( is_string( $column ) && !in_array( $column, [ '*', '1' ] ) ) {
1862                         $conds[] = "$column IS NOT NULL";
1863                 }
1864
1865                 $res = $this->select(
1866                         $table, [ 'rowcount' => 'COUNT(*)' ], $conds, $fname, $options, $join_conds
1867                 );
1868                 $row = $res ? $this->fetchRow( $res ) : [];
1869
1870                 return isset( $row['rowcount'] ) ? (int)$row['rowcount'] : 0;
1871         }
1872
1873         public function selectRowCount(
1874                 $tables, $var = '*', $conds = '', $fname = __METHOD__, $options = [], $join_conds = []
1875         ) {
1876                 $conds = $this->normalizeConditions( $conds, $fname );
1877                 $column = $this->extractSingleFieldFromList( $var );
1878                 if ( is_string( $column ) && !in_array( $column, [ '*', '1' ] ) ) {
1879                         $conds[] = "$column IS NOT NULL";
1880                 }
1881
1882                 $res = $this->select(
1883                         [
1884                                 'tmp_count' => $this->buildSelectSubquery(
1885                                         $tables,
1886                                         '1',
1887                                         $conds,
1888                                         $fname,
1889                                         $options,
1890                                         $join_conds
1891                                 )
1892                         ],
1893                         [ 'rowcount' => 'COUNT(*)' ],
1894                         [],
1895                         $fname
1896                 );
1897                 $row = $res ? $this->fetchRow( $res ) : [];
1898
1899                 return isset( $row['rowcount'] ) ? (int)$row['rowcount'] : 0;
1900         }
1901
1902         /**
1903          * @param string|array $options
1904          * @return bool
1905          */
1906         private function selectOptionsIncludeLocking( $options ) {
1907                 $options = (array)$options;
1908                 foreach ( [ 'FOR UPDATE', 'LOCK IN SHARE MODE' ] as $lock ) {
1909                         if ( in_array( $lock, $options, true ) ) {
1910                                 return true;
1911                         }
1912                 }
1913
1914                 return false;
1915         }
1916
1917         /**
1918          * @param array|string $fields
1919          * @param array|string $options
1920          * @return bool
1921          */
1922         private function selectFieldsOrOptionsAggregate( $fields, $options ) {
1923                 foreach ( (array)$options as $key => $value ) {
1924                         if ( is_string( $key ) ) {
1925                                 if ( preg_match( '/^(?:GROUP BY|HAVING)$/i', $key ) ) {
1926                                         return true;
1927                                 }
1928                         } elseif ( is_string( $value ) ) {
1929                                 if ( preg_match( '/^(?:DISTINCT|DISTINCTROW)$/i', $value ) ) {
1930                                         return true;
1931                                 }
1932                         }
1933                 }
1934
1935                 $regex = '/^(?:COUNT|MIN|MAX|SUM|GROUP_CONCAT|LISTAGG|ARRAY_AGG)\s*\\(/i';
1936                 foreach ( (array)$fields as $field ) {
1937                         if ( is_string( $field ) && preg_match( $regex, $field ) ) {
1938                                 return true;
1939                         }
1940                 }
1941
1942                 return false;
1943         }
1944
1945         /**
1946          * @param array|string $conds
1947          * @param string $fname
1948          * @return array
1949          */
1950         final protected function normalizeConditions( $conds, $fname ) {
1951                 if ( $conds === null || $conds === false ) {
1952                         $this->queryLogger->warning(
1953                                 __METHOD__
1954                                 . ' called from '
1955                                 . $fname
1956                                 . ' with incorrect parameters: $conds must be a string or an array'
1957                         );
1958                         $conds = '';
1959                 }
1960
1961                 if ( !is_array( $conds ) ) {
1962                         $conds = ( $conds === '' ) ? [] : [ $conds ];
1963                 }
1964
1965                 return $conds;
1966         }
1967
1968         /**
1969          * @param array|string $var Field parameter in the style of select()
1970          * @return string|null Column name or null; ignores aliases
1971          * @throws DBUnexpectedError Errors out if multiple columns are given
1972          */
1973         final protected function extractSingleFieldFromList( $var ) {
1974                 if ( is_array( $var ) ) {
1975                         if ( !$var ) {
1976                                 $column = null;
1977                         } elseif ( count( $var ) == 1 ) {
1978                                 $column = $var[0] ?? reset( $var );
1979                         } else {
1980                                 throw new DBUnexpectedError( $this, __METHOD__ . ': got multiple columns.' );
1981                         }
1982                 } else {
1983                         $column = $var;
1984                 }
1985
1986                 return $column;
1987         }
1988
1989         public function lockForUpdate(
1990                 $table, $conds = '', $fname = __METHOD__, $options = [], $join_conds = []
1991         ) {
1992                 if ( !$this->trxLevel && !$this->getFlag( self::DBO_TRX ) ) {
1993                         throw new DBUnexpectedError(
1994                                 $this,
1995                                 __METHOD__ . ': no transaction is active nor is DBO_TRX set'
1996                         );
1997                 }
1998
1999                 $options = (array)$options;
2000                 $options[] = 'FOR UPDATE';
2001
2002                 return $this->selectRowCount( $table, '*', $conds, $fname, $options, $join_conds );
2003         }
2004
2005         public function fieldExists( $table, $field, $fname = __METHOD__ ) {
2006                 $info = $this->fieldInfo( $table, $field );
2007
2008                 return (bool)$info;
2009         }
2010
2011         public function indexExists( $table, $index, $fname = __METHOD__ ) {
2012                 if ( !$this->tableExists( $table ) ) {
2013                         return null;
2014                 }
2015
2016                 $info = $this->indexInfo( $table, $index, $fname );
2017                 if ( is_null( $info ) ) {
2018                         return null;
2019                 } else {
2020                         return $info !== false;
2021                 }
2022         }
2023
2024         abstract public function tableExists( $table, $fname = __METHOD__ );
2025
2026         public function indexUnique( $table, $index ) {
2027                 $indexInfo = $this->indexInfo( $table, $index );
2028
2029                 if ( !$indexInfo ) {
2030                         return null;
2031                 }
2032
2033                 return !$indexInfo[0]->Non_unique;
2034         }
2035
2036         /**
2037          * Helper for Database::insert().
2038          *
2039          * @param array $options
2040          * @return string
2041          */
2042         protected function makeInsertOptions( $options ) {
2043                 return implode( ' ', $options );
2044         }
2045
2046         public function insert( $table, $a, $fname = __METHOD__, $options = [] ) {
2047                 # No rows to insert, easy just return now
2048                 if ( !count( $a ) ) {
2049                         return true;
2050                 }
2051
2052                 $table = $this->tableName( $table );
2053
2054                 if ( !is_array( $options ) ) {
2055                         $options = [ $options ];
2056                 }
2057
2058                 $options = $this->makeInsertOptions( $options );
2059
2060                 if ( isset( $a[0] ) && is_array( $a[0] ) ) {
2061                         $multi = true;
2062                         $keys = array_keys( $a[0] );
2063                 } else {
2064                         $multi = false;
2065                         $keys = array_keys( $a );
2066                 }
2067
2068                 $sql = 'INSERT ' . $options .
2069                         " INTO $table (" . implode( ',', $keys ) . ') VALUES ';
2070
2071                 if ( $multi ) {
2072                         $first = true;
2073                         foreach ( $a as $row ) {
2074                                 if ( $first ) {
2075                                         $first = false;
2076                                 } else {
2077                                         $sql .= ',';
2078                                 }
2079                                 $sql .= '(' . $this->makeList( $row ) . ')';
2080                         }
2081                 } else {
2082                         $sql .= '(' . $this->makeList( $a ) . ')';
2083                 }
2084
2085                 $this->query( $sql, $fname );
2086
2087                 return true;
2088         }
2089
2090         /**
2091          * Make UPDATE options array for Database::makeUpdateOptions
2092          *
2093          * @param array $options
2094          * @return array
2095          */
2096         protected function makeUpdateOptionsArray( $options ) {
2097                 if ( !is_array( $options ) ) {
2098                         $options = [ $options ];
2099                 }
2100
2101                 $opts = [];
2102
2103                 if ( in_array( 'IGNORE', $options ) ) {
2104                         $opts[] = 'IGNORE';
2105                 }
2106
2107                 return $opts;
2108         }
2109
2110         /**
2111          * Make UPDATE options for the Database::update function
2112          *
2113          * @param array $options The options passed to Database::update
2114          * @return string
2115          */
2116         protected function makeUpdateOptions( $options ) {
2117                 $opts = $this->makeUpdateOptionsArray( $options );
2118
2119                 return implode( ' ', $opts );
2120         }
2121
2122         public function update( $table, $values, $conds, $fname = __METHOD__, $options = [] ) {
2123                 $table = $this->tableName( $table );
2124                 $opts = $this->makeUpdateOptions( $options );
2125                 $sql = "UPDATE $opts $table SET " . $this->makeList( $values, self::LIST_SET );
2126
2127                 if ( $conds !== [] && $conds !== '*' ) {
2128                         $sql .= " WHERE " . $this->makeList( $conds, self::LIST_AND );
2129                 }
2130
2131                 $this->query( $sql, $fname );
2132
2133                 return true;
2134         }
2135
2136         public function makeList( $a, $mode = self::LIST_COMMA ) {
2137                 if ( !is_array( $a ) ) {
2138                         throw new DBUnexpectedError( $this, __METHOD__ . ' called with incorrect parameters' );
2139                 }
2140
2141                 $first = true;
2142                 $list = '';
2143
2144                 foreach ( $a as $field => $value ) {
2145                         if ( !$first ) {
2146                                 if ( $mode == self::LIST_AND ) {
2147                                         $list .= ' AND ';
2148                                 } elseif ( $mode == self::LIST_OR ) {
2149                                         $list .= ' OR ';
2150                                 } else {
2151                                         $list .= ',';
2152                                 }
2153                         } else {
2154                                 $first = false;
2155                         }
2156
2157                         if ( ( $mode == self::LIST_AND || $mode == self::LIST_OR ) && is_numeric( $field ) ) {
2158                                 $list .= "($value)";
2159                         } elseif ( $mode == self::LIST_SET && is_numeric( $field ) ) {
2160                                 $list .= "$value";
2161                         } elseif (
2162                                 ( $mode == self::LIST_AND || $mode == self::LIST_OR ) && is_array( $value )
2163                         ) {
2164                                 // Remove null from array to be handled separately if found
2165                                 $includeNull = false;
2166                                 foreach ( array_keys( $value, null, true ) as $nullKey ) {
2167                                         $includeNull = true;
2168                                         unset( $value[$nullKey] );
2169                                 }
2170                                 if ( count( $value ) == 0 && !$includeNull ) {
2171                                         throw new InvalidArgumentException(
2172                                                 __METHOD__ . ": empty input for field $field" );
2173                                 } elseif ( count( $value ) == 0 ) {
2174                                         // only check if $field is null
2175                                         $list .= "$field IS NULL";
2176                                 } else {
2177                                         // IN clause contains at least one valid element
2178                                         if ( $includeNull ) {
2179                                                 // Group subconditions to ensure correct precedence
2180                                                 $list .= '(';
2181                                         }
2182                                         if ( count( $value ) == 1 ) {
2183                                                 // Special-case single values, as IN isn't terribly efficient
2184                                                 // Don't necessarily assume the single key is 0; we don't
2185                                                 // enforce linear numeric ordering on other arrays here.
2186                                                 $value = array_values( $value )[0];
2187                                                 $list .= $field . " = " . $this->addQuotes( $value );
2188                                         } else {
2189                                                 $list .= $field . " IN (" . $this->makeList( $value ) . ") ";
2190                                         }
2191                                         // if null present in array, append IS NULL
2192                                         if ( $includeNull ) {
2193                                                 $list .= " OR $field IS NULL)";
2194                                         }
2195                                 }
2196                         } elseif ( $value === null ) {
2197                                 if ( $mode == self::LIST_AND || $mode == self::LIST_OR ) {
2198                                         $list .= "$field IS ";
2199                                 } elseif ( $mode == self::LIST_SET ) {
2200                                         $list .= "$field = ";
2201                                 }
2202                                 $list .= 'NULL';
2203                         } else {
2204                                 if (
2205                                         $mode == self::LIST_AND || $mode == self::LIST_OR || $mode == self::LIST_SET
2206                                 ) {
2207                                         $list .= "$field = ";
2208                                 }
2209                                 $list .= $mode == self::LIST_NAMES ? $value : $this->addQuotes( $value );
2210                         }
2211                 }
2212
2213                 return $list;
2214         }
2215
2216         public function makeWhereFrom2d( $data, $baseKey, $subKey ) {
2217                 $conds = [];
2218
2219                 foreach ( $data as $base => $sub ) {
2220                         if ( count( $sub ) ) {
2221                                 $conds[] = $this->makeList(
2222                                         [ $baseKey => $base, $subKey => array_keys( $sub ) ],
2223                                         self::LIST_AND );
2224                         }
2225                 }
2226
2227                 if ( $conds ) {
2228                         return $this->makeList( $conds, self::LIST_OR );
2229                 } else {
2230                         // Nothing to search for...
2231                         return false;
2232                 }
2233         }
2234
2235         public function aggregateValue( $valuedata, $valuename = 'value' ) {
2236                 return $valuename;
2237         }
2238
2239         public function bitNot( $field ) {
2240                 return "(~$field)";
2241         }
2242
2243         public function bitAnd( $fieldLeft, $fieldRight ) {
2244                 return "($fieldLeft & $fieldRight)";
2245         }
2246
2247         public function bitOr( $fieldLeft, $fieldRight ) {
2248                 return "($fieldLeft | $fieldRight)";
2249         }
2250
2251         public function buildConcat( $stringList ) {
2252                 return 'CONCAT(' . implode( ',', $stringList ) . ')';
2253         }
2254
2255         public function buildGroupConcatField(
2256                 $delim, $table, $field, $conds = '', $join_conds = []
2257         ) {
2258                 $fld = "GROUP_CONCAT($field SEPARATOR " . $this->addQuotes( $delim ) . ')';
2259
2260                 return '(' . $this->selectSQLText( $table, $fld, $conds, null, [], $join_conds ) . ')';
2261         }
2262
2263         public function buildSubstring( $input, $startPosition, $length = null ) {
2264                 $this->assertBuildSubstringParams( $startPosition, $length );
2265                 $functionBody = "$input FROM $startPosition";
2266                 if ( $length !== null ) {
2267                         $functionBody .= " FOR $length";
2268                 }
2269                 return 'SUBSTRING(' . $functionBody . ')';
2270         }
2271
2272         /**
2273          * Check type and bounds for parameters to self::buildSubstring()
2274          *
2275          * All supported databases have substring functions that behave the same for
2276          * positive $startPosition and non-negative $length, but behaviors differ when
2277          * given 0 or negative $startPosition or negative $length. The simplest
2278          * solution to that is to just forbid those values.
2279          *
2280          * @param int $startPosition
2281          * @param int|null $length
2282          * @since 1.31
2283          */
2284         protected function assertBuildSubstringParams( $startPosition, $length ) {
2285                 if ( !is_int( $startPosition ) || $startPosition <= 0 ) {
2286                         throw new InvalidArgumentException(
2287                                 '$startPosition must be a positive integer'
2288                         );
2289                 }
2290                 if ( !( is_int( $length ) && $length >= 0 || $length === null ) ) {
2291                         throw new InvalidArgumentException(
2292                                 '$length must be null or an integer greater than or equal to 0'
2293                         );
2294                 }
2295         }
2296
2297         public function buildStringCast( $field ) {
2298                 // In theory this should work for any standards-compliant
2299                 // SQL implementation, although it may not be the best way to do it.
2300                 return "CAST( $field AS CHARACTER )";
2301         }
2302
2303         public function buildIntegerCast( $field ) {
2304                 return 'CAST( ' . $field . ' AS INTEGER )';
2305         }
2306
2307         public function buildSelectSubquery(
2308                 $table, $vars, $conds = '', $fname = __METHOD__,
2309                 $options = [], $join_conds = []
2310         ) {
2311                 return new Subquery(
2312                         $this->selectSQLText( $table, $vars, $conds, $fname, $options, $join_conds )
2313                 );
2314         }
2315
2316         public function databasesAreIndependent() {
2317                 return false;
2318         }
2319
2320         final public function selectDB( $db ) {
2321                 $this->selectDomain( new DatabaseDomain(
2322                         $db,
2323                         $this->currentDomain->getSchema(),
2324                         $this->currentDomain->getTablePrefix()
2325                 ) );
2326
2327                 return true;
2328         }
2329
2330         final public function selectDomain( $domain ) {
2331                 $this->doSelectDomain( DatabaseDomain::newFromId( $domain ) );
2332         }
2333
2334         protected function doSelectDomain( DatabaseDomain $domain ) {
2335                 $this->currentDomain = $domain;
2336         }
2337
2338         public function getDBname() {
2339                 return $this->currentDomain->getDatabase();
2340         }
2341
2342         public function getServer() {
2343                 return $this->server;
2344         }
2345
2346         public function tableName( $name, $format = 'quoted' ) {
2347                 if ( $name instanceof Subquery ) {
2348                         throw new DBUnexpectedError(
2349                                 $this,
2350                                 __METHOD__ . ': got Subquery instance when expecting a string.'
2351                         );
2352                 }
2353
2354                 # Skip the entire process when we have a string quoted on both ends.
2355                 # Note that we check the end so that we will still quote any use of
2356                 # use of `database`.table. But won't break things if someone wants
2357                 # to query a database table with a dot in the name.
2358                 if ( $this->isQuotedIdentifier( $name ) ) {
2359                         return $name;
2360                 }
2361
2362                 # Lets test for any bits of text that should never show up in a table
2363                 # name. Basically anything like JOIN or ON which are actually part of
2364                 # SQL queries, but may end up inside of the table value to combine
2365                 # sql. Such as how the API is doing.
2366                 # Note that we use a whitespace test rather than a \b test to avoid
2367                 # any remote case where a word like on may be inside of a table name
2368                 # surrounded by symbols which may be considered word breaks.
2369                 if ( preg_match( '/(^|\s)(DISTINCT|JOIN|ON|AS)(\s|$)/i', $name ) !== 0 ) {
2370                         $this->queryLogger->warning(
2371                                 __METHOD__ . ": use of subqueries is not supported this way.",
2372                                 [ 'trace' => ( new RuntimeException() )->getTraceAsString() ]
2373                         );
2374
2375                         return $name;
2376                 }
2377
2378                 # Split database and table into proper variables.
2379                 list( $database, $schema, $prefix, $table ) = $this->qualifiedTableComponents( $name );
2380
2381                 # Quote $table and apply the prefix if not quoted.
2382                 # $tableName might be empty if this is called from Database::replaceVars()
2383                 $tableName = "{$prefix}{$table}";
2384                 if ( $format === 'quoted'
2385                         && !$this->isQuotedIdentifier( $tableName )
2386                         && $tableName !== ''
2387                 ) {
2388                         $tableName = $this->addIdentifierQuotes( $tableName );
2389                 }
2390
2391                 # Quote $schema and $database and merge them with the table name if needed
2392                 $tableName = $this->prependDatabaseOrSchema( $schema, $tableName, $format );
2393                 $tableName = $this->prependDatabaseOrSchema( $database, $tableName, $format );
2394
2395                 return $tableName;
2396         }
2397
2398         /**
2399          * Get the table components needed for a query given the currently selected database
2400          *
2401          * @param string $name Table name in the form of db.schema.table, db.table, or table
2402          * @return array (DB name or "" for default, schema name, table prefix, table name)
2403          */
2404         protected function qualifiedTableComponents( $name ) {
2405                 # We reverse the explode so that database.table and table both output the correct table.
2406                 $dbDetails = explode( '.', $name, 3 );
2407                 if ( count( $dbDetails ) == 3 ) {
2408                         list( $database, $schema, $table ) = $dbDetails;
2409                         # We don't want any prefix added in this case
2410                         $prefix = '';
2411                 } elseif ( count( $dbDetails ) == 2 ) {
2412                         list( $database, $table ) = $dbDetails;
2413                         # We don't want any prefix added in this case
2414                         $prefix = '';
2415                         # In dbs that support it, $database may actually be the schema
2416                         # but that doesn't affect any of the functionality here
2417                         $schema = '';
2418                 } else {
2419                         list( $table ) = $dbDetails;
2420                         if ( isset( $this->tableAliases[$table] ) ) {
2421                                 $database = $this->tableAliases[$table]['dbname'];
2422                                 $schema = is_string( $this->tableAliases[$table]['schema'] )
2423                                         ? $this->tableAliases[$table]['schema']
2424                                         : $this->relationSchemaQualifier();
2425                                 $prefix = is_string( $this->tableAliases[$table]['prefix'] )
2426                                         ? $this->tableAliases[$table]['prefix']
2427                                         : $this->tablePrefix();
2428                         } else {
2429                                 $database = '';
2430                                 $schema = $this->relationSchemaQualifier(); # Default schema
2431                                 $prefix = $this->tablePrefix(); # Default prefix
2432                         }
2433                 }
2434
2435                 return [ $database, $schema, $prefix, $table ];
2436         }
2437
2438         /**
2439          * @param string|null $namespace Database or schema
2440          * @param string $relation Name of table, view, sequence, etc...
2441          * @param string $format One of (raw, quoted)
2442          * @return string Relation name with quoted and merged $namespace as needed
2443          */
2444         private function prependDatabaseOrSchema( $namespace, $relation, $format ) {
2445                 if ( strlen( $namespace ) ) {
2446                         if ( $format === 'quoted' && !$this->isQuotedIdentifier( $namespace ) ) {
2447                                 $namespace = $this->addIdentifierQuotes( $namespace );
2448                         }
2449                         $relation = $namespace . '.' . $relation;
2450                 }
2451
2452                 return $relation;
2453         }
2454
2455         public function tableNames() {
2456                 $inArray = func_get_args();
2457                 $retVal = [];
2458
2459                 foreach ( $inArray as $name ) {
2460                         $retVal[$name] = $this->tableName( $name );
2461                 }
2462
2463                 return $retVal;
2464         }
2465
2466         public function tableNamesN() {
2467                 $inArray = func_get_args();
2468                 $retVal = [];
2469
2470                 foreach ( $inArray as $name ) {
2471                         $retVal[] = $this->tableName( $name );
2472                 }
2473
2474                 return $retVal;
2475         }
2476
2477         /**
2478          * Get an aliased table name
2479          *
2480          * This returns strings like "tableName AS newTableName" for aliased tables
2481          * and "(SELECT * from tableA) newTablename" for subqueries (e.g. derived tables)
2482          *
2483          * @see Database::tableName()
2484          * @param string|Subquery $table Table name or object with a 'sql' field
2485          * @param string|bool $alias Table alias (optional)
2486          * @return string SQL name for aliased table. Will not alias a table to its own name
2487          */
2488         protected function tableNameWithAlias( $table, $alias = false ) {
2489                 if ( is_string( $table ) ) {
2490                         $quotedTable = $this->tableName( $table );
2491                 } elseif ( $table instanceof Subquery ) {
2492                         $quotedTable = (string)$table;
2493                 } else {
2494                         throw new InvalidArgumentException( "Table must be a string or Subquery." );
2495                 }
2496
2497                 if ( $alias === false || $alias === $table ) {
2498                         if ( $table instanceof Subquery ) {
2499                                 throw new InvalidArgumentException( "Subquery table missing alias." );
2500                         }
2501
2502                         return $quotedTable;
2503                 } else {
2504                         return $quotedTable . ' ' . $this->addIdentifierQuotes( $alias );
2505                 }
2506         }
2507
2508         /**
2509          * Gets an array of aliased table names
2510          *
2511          * @param array $tables [ [alias] => table ]
2512          * @return string[] See tableNameWithAlias()
2513          */
2514         protected function tableNamesWithAlias( $tables ) {
2515                 $retval = [];
2516                 foreach ( $tables as $alias => $table ) {
2517                         if ( is_numeric( $alias ) ) {
2518                                 $alias = $table;
2519                         }
2520                         $retval[] = $this->tableNameWithAlias( $table, $alias );
2521                 }
2522
2523                 return $retval;
2524         }
2525
2526         /**
2527          * Get an aliased field name
2528          * e.g. fieldName AS newFieldName
2529          *
2530          * @param string $name Field name
2531          * @param string|bool $alias Alias (optional)
2532          * @return string SQL name for aliased field. Will not alias a field to its own name
2533          */
2534         protected function fieldNameWithAlias( $name, $alias = false ) {
2535                 if ( !$alias || (string)$alias === (string)$name ) {
2536                         return $name;
2537                 } else {
2538                         return $name . ' AS ' . $this->addIdentifierQuotes( $alias ); // PostgreSQL needs AS
2539                 }
2540         }
2541
2542         /**
2543          * Gets an array of aliased field names
2544          *
2545          * @param array $fields [ [alias] => field ]
2546          * @return string[] See fieldNameWithAlias()
2547          */
2548         protected function fieldNamesWithAlias( $fields ) {
2549                 $retval = [];
2550                 foreach ( $fields as $alias => $field ) {
2551                         if ( is_numeric( $alias ) ) {
2552                                 $alias = $field;
2553                         }
2554                         $retval[] = $this->fieldNameWithAlias( $field, $alias );
2555                 }
2556
2557                 return $retval;
2558         }
2559
2560         /**
2561          * Get the aliased table name clause for a FROM clause
2562          * which might have a JOIN and/or USE INDEX or IGNORE INDEX clause
2563          *
2564          * @param array $tables ( [alias] => table )
2565          * @param array $use_index Same as for select()
2566          * @param array $ignore_index Same as for select()
2567          * @param array $join_conds Same as for select()
2568          * @return string
2569          */
2570         protected function tableNamesWithIndexClauseOrJOIN(
2571                 $tables, $use_index = [], $ignore_index = [], $join_conds = []
2572         ) {
2573                 $ret = [];
2574                 $retJOIN = [];
2575                 $use_index = (array)$use_index;
2576                 $ignore_index = (array)$ignore_index;
2577                 $join_conds = (array)$join_conds;
2578
2579                 foreach ( $tables as $alias => $table ) {
2580                         if ( !is_string( $alias ) ) {
2581                                 // No alias? Set it equal to the table name
2582                                 $alias = $table;
2583                         }
2584
2585                         if ( is_array( $table ) ) {
2586                                 // A parenthesized group
2587                                 if ( count( $table ) > 1 ) {
2588                                         $joinedTable = '(' .
2589                                                 $this->tableNamesWithIndexClauseOrJOIN(
2590                                                         $table, $use_index, $ignore_index, $join_conds ) . ')';
2591                                 } else {
2592                                         // Degenerate case
2593                                         $innerTable = reset( $table );
2594                                         $innerAlias = key( $table );
2595                                         $joinedTable = $this->tableNameWithAlias(
2596                                                 $innerTable,
2597                                                 is_string( $innerAlias ) ? $innerAlias : $innerTable
2598                                         );
2599                                 }
2600                         } else {
2601                                 $joinedTable = $this->tableNameWithAlias( $table, $alias );
2602                         }
2603
2604                         // Is there a JOIN clause for this table?
2605                         if ( isset( $join_conds[$alias] ) ) {
2606                                 list( $joinType, $conds ) = $join_conds[$alias];
2607                                 $tableClause = $joinType;
2608                                 $tableClause .= ' ' . $joinedTable;
2609                                 if ( isset( $use_index[$alias] ) ) { // has USE INDEX?
2610                                         $use = $this->useIndexClause( implode( ',', (array)$use_index[$alias] ) );
2611                                         if ( $use != '' ) {
2612                                                 $tableClause .= ' ' . $use;
2613                                         }
2614                                 }
2615                                 if ( isset( $ignore_index[$alias] ) ) { // has IGNORE INDEX?
2616                                         $ignore = $this->ignoreIndexClause(
2617                                                 implode( ',', (array)$ignore_index[$alias] ) );
2618                                         if ( $ignore != '' ) {
2619                                                 $tableClause .= ' ' . $ignore;
2620                                         }
2621                                 }
2622                                 $on = $this->makeList( (array)$conds, self::LIST_AND );
2623                                 if ( $on != '' ) {
2624                                         $tableClause .= ' ON (' . $on . ')';
2625                                 }
2626
2627                                 $retJOIN[] = $tableClause;
2628                         } elseif ( isset( $use_index[$alias] ) ) {
2629                                 // Is there an INDEX clause for this table?
2630                                 $tableClause = $joinedTable;
2631                                 $tableClause .= ' ' . $this->useIndexClause(
2632                                                 implode( ',', (array)$use_index[$alias] )
2633                                         );
2634
2635                                 $ret[] = $tableClause;
2636                         } elseif ( isset( $ignore_index[$alias] ) ) {
2637                                 // Is there an INDEX clause for this table?
2638                                 $tableClause = $joinedTable;
2639                                 $tableClause .= ' ' . $this->ignoreIndexClause(
2640                                                 implode( ',', (array)$ignore_index[$alias] )
2641                                         );
2642
2643                                 $ret[] = $tableClause;
2644                         } else {
2645                                 $tableClause = $joinedTable;
2646
2647                                 $ret[] = $tableClause;
2648                         }
2649                 }
2650
2651                 // We can't separate explicit JOIN clauses with ',', use ' ' for those
2652                 $implicitJoins = implode( ',', $ret );
2653                 $explicitJoins = implode( ' ', $retJOIN );
2654
2655                 // Compile our final table clause
2656                 return implode( ' ', [ $implicitJoins, $explicitJoins ] );
2657         }
2658
2659         /**
2660          * Allows for index remapping in queries where this is not consistent across DBMS
2661          *
2662          * @param string $index
2663          * @return string
2664          */
2665         protected function indexName( $index ) {
2666                 return $this->indexAliases[$index] ?? $index;
2667         }
2668
2669         public function addQuotes( $s ) {
2670                 if ( $s instanceof Blob ) {
2671                         $s = $s->fetch();
2672                 }
2673                 if ( $s === null ) {
2674                         return 'NULL';
2675                 } elseif ( is_bool( $s ) ) {
2676                         return (int)$s;
2677                 } else {
2678                         # This will also quote numeric values. This should be harmless,
2679                         # and protects against weird problems that occur when they really
2680                         # _are_ strings such as article titles and string->number->string
2681                         # conversion is not 1:1.
2682                         return "'" . $this->strencode( $s ) . "'";
2683                 }
2684         }
2685
2686         public function addIdentifierQuotes( $s ) {
2687                 return '"' . str_replace( '"', '""', $s ) . '"';
2688         }
2689
2690         /**
2691          * Returns if the given identifier looks quoted or not according to
2692          * the database convention for quoting identifiers .
2693          *
2694          * @note Do not use this to determine if untrusted input is safe.
2695          *   A malicious user can trick this function.
2696          * @param string $name
2697          * @return bool
2698          */
2699         public function isQuotedIdentifier( $name ) {
2700                 return $name[0] == '"' && substr( $name, -1, 1 ) == '"';
2701         }
2702
2703         /**
2704          * @param string $s
2705          * @param string $escapeChar
2706          * @return string
2707          */
2708         protected function escapeLikeInternal( $s, $escapeChar = '`' ) {
2709                 return str_replace( [ $escapeChar, '%', '_' ],
2710                         [ "{$escapeChar}{$escapeChar}", "{$escapeChar}%", "{$escapeChar}_" ],
2711                         $s );
2712         }
2713
2714         public function buildLike( $param, ...$params ) {
2715                 if ( is_array( $param ) ) {
2716                         $params = $param;
2717                 } else {
2718                         $params = func_get_args();
2719                 }
2720
2721                 $s = '';
2722
2723                 // We use ` instead of \ as the default LIKE escape character, since addQuotes()
2724                 // may escape backslashes, creating problems of double escaping. The `
2725                 // character has good cross-DBMS compatibility, avoiding special operators
2726                 // in MS SQL like ^ and %
2727                 $escapeChar = '`';
2728
2729                 foreach ( $params as $value ) {
2730                         if ( $value instanceof LikeMatch ) {
2731                                 $s .= $value->toString();
2732                         } else {
2733                                 $s .= $this->escapeLikeInternal( $value, $escapeChar );
2734                         }
2735                 }
2736
2737                 return ' LIKE ' .
2738                         $this->addQuotes( $s ) . ' ESCAPE ' . $this->addQuotes( $escapeChar ) . ' ';
2739         }
2740
2741         public function anyChar() {
2742                 return new LikeMatch( '_' );
2743         }
2744
2745         public function anyString() {
2746                 return new LikeMatch( '%' );
2747         }
2748
2749         public function nextSequenceValue( $seqName ) {
2750                 return null;
2751         }
2752
2753         /**
2754          * USE INDEX clause. Unlikely to be useful for anything but MySQL. This
2755          * is only needed because a) MySQL must be as efficient as possible due to
2756          * its use on Wikipedia, and b) MySQL 4.0 is kind of dumb sometimes about
2757          * which index to pick. Anyway, other databases might have different
2758          * indexes on a given table. So don't bother overriding this unless you're
2759          * MySQL.
2760          * @param string $index
2761          * @return string
2762          */
2763         public function useIndexClause( $index ) {
2764                 return '';
2765         }
2766
2767         /**
2768          * IGNORE INDEX clause. Unlikely to be useful for anything but MySQL. This
2769          * is only needed because a) MySQL must be as efficient as possible due to
2770          * its use on Wikipedia, and b) MySQL 4.0 is kind of dumb sometimes about
2771          * which index to pick. Anyway, other databases might have different
2772          * indexes on a given table. So don't bother overriding this unless you're
2773          * MySQL.
2774          * @param string $index
2775          * @return string
2776          */
2777         public function ignoreIndexClause( $index ) {
2778                 return '';
2779         }
2780
2781         public function replace( $table, $uniqueIndexes, $rows, $fname = __METHOD__ ) {
2782                 if ( count( $rows ) == 0 ) {
2783                         return;
2784                 }
2785
2786                 $uniqueIndexes = (array)$uniqueIndexes;
2787                 // Single row case
2788                 if ( !is_array( reset( $rows ) ) ) {
2789                         $rows = [ $rows ];
2790                 }
2791
2792                 try {
2793                         $this->startAtomic( $fname, self::ATOMIC_CANCELABLE );
2794                         $affectedRowCount = 0;
2795                         foreach ( $rows as $row ) {
2796                                 // Delete rows which collide with this one
2797                                 $indexWhereClauses = [];
2798                                 foreach ( $uniqueIndexes as $index ) {
2799                                         $indexColumns = (array)$index;
2800                                         $indexRowValues = array_intersect_key( $row, array_flip( $indexColumns ) );
2801                                         if ( count( $indexRowValues ) != count( $indexColumns ) ) {
2802                                                 throw new DBUnexpectedError(
2803                                                         $this,
2804                                                         'New record does not provide all values for unique key (' .
2805                                                         implode( ', ', $indexColumns ) . ')'
2806                                                 );
2807                                         } elseif ( in_array( null, $indexRowValues, true ) ) {
2808                                                 throw new DBUnexpectedError(
2809                                                         $this,
2810                                                         'New record has a null value for unique key (' .
2811                                                         implode( ', ', $indexColumns ) . ')'
2812                                                 );
2813                                         }
2814                                         $indexWhereClauses[] = $this->makeList( $indexRowValues, LIST_AND );
2815                                 }
2816
2817                                 if ( $indexWhereClauses ) {
2818                                         $this->delete( $table, $this->makeList( $indexWhereClauses, LIST_OR ), $fname );
2819                                         $affectedRowCount += $this->affectedRows();
2820                                 }
2821
2822                                 // Now insert the row
2823                                 $this->insert( $table, $row, $fname );
2824                                 $affectedRowCount += $this->affectedRows();
2825                         }
2826                         $this->endAtomic( $fname );
2827                         $this->affectedRowCount = $affectedRowCount;
2828                 } catch ( Exception $e ) {
2829                         $this->cancelAtomic( $fname );
2830                         throw $e;
2831                 }
2832         }
2833
2834         /**
2835          * REPLACE query wrapper for MySQL and SQLite, which have a native REPLACE
2836          * statement.
2837          *
2838          * @param string $table Table name
2839          * @param array|string $rows Row(s) to insert
2840          * @param string $fname Caller function name
2841          */
2842         protected function nativeReplace( $table, $rows, $fname ) {
2843                 $table = $this->tableName( $table );
2844
2845                 # Single row case
2846                 if ( !is_array( reset( $rows ) ) ) {
2847                         $rows = [ $rows ];
2848                 }
2849
2850                 $sql = "REPLACE INTO $table (" . implode( ',', array_keys( $rows[0] ) ) . ') VALUES ';
2851                 $first = true;
2852
2853                 foreach ( $rows as $row ) {
2854                         if ( $first ) {
2855                                 $first = false;
2856                         } else {
2857                                 $sql .= ',';
2858                         }
2859
2860                         $sql .= '(' . $this->makeList( $row ) . ')';
2861                 }
2862
2863                 $this->query( $sql, $fname );
2864         }
2865
2866         public function upsert( $table, array $rows, $uniqueIndexes, array $set,
2867                 $fname = __METHOD__
2868         ) {
2869                 if ( $rows === [] ) {
2870                         return true; // nothing to do
2871                 }
2872
2873                 $uniqueIndexes = (array)$uniqueIndexes;
2874                 if ( !is_array( reset( $rows ) ) ) {
2875                         $rows = [ $rows ];
2876                 }
2877
2878                 if ( count( $uniqueIndexes ) ) {
2879                         $clauses = []; // list WHERE clauses that each identify a single row
2880                         foreach ( $rows as $row ) {
2881                                 foreach ( $uniqueIndexes as $index ) {
2882                                         $index = is_array( $index ) ? $index : [ $index ]; // columns
2883                                         $rowKey = []; // unique key to this row
2884                                         foreach ( $index as $column ) {
2885                                                 $rowKey[$column] = $row[$column];
2886                                         }
2887                                         $clauses[] = $this->makeList( $rowKey, self::LIST_AND );
2888                                 }
2889                         }
2890                         $where = [ $this->makeList( $clauses, self::LIST_OR ) ];
2891                 } else {
2892                         $where = false;
2893                 }
2894
2895                 $affectedRowCount = 0;
2896                 try {
2897                         $this->startAtomic( $fname, self::ATOMIC_CANCELABLE );
2898                         # Update any existing conflicting row(s)
2899                         if ( $where !== false ) {
2900                                 $this->update( $table, $set, $where, $fname );
2901                                 $affectedRowCount += $this->affectedRows();
2902                         }
2903                         # Now insert any non-conflicting row(s)
2904                         $this->insert( $table, $rows, $fname, [ 'IGNORE' ] );
2905                         $affectedRowCount += $this->affectedRows();
2906                         $this->endAtomic( $fname );
2907                         $this->affectedRowCount = $affectedRowCount;
2908                 } catch ( Exception $e ) {
2909                         $this->cancelAtomic( $fname );
2910                         throw $e;
2911                 }
2912
2913                 return true;
2914         }
2915
2916         public function deleteJoin( $delTable, $joinTable, $delVar, $joinVar, $conds,
2917                 $fname = __METHOD__
2918         ) {
2919                 if ( !$conds ) {
2920                         throw new DBUnexpectedError( $this, __METHOD__ . ' called with empty $conds' );
2921                 }
2922
2923                 $delTable = $this->tableName( $delTable );
2924                 $joinTable = $this->tableName( $joinTable );
2925                 $sql = "DELETE FROM $delTable WHERE $delVar IN (SELECT $joinVar FROM $joinTable ";
2926                 if ( $conds != '*' ) {
2927                         $sql .= 'WHERE ' . $this->makeList( $conds, self::LIST_AND );
2928                 }
2929                 $sql .= ')';
2930
2931                 $this->query( $sql, $fname );
2932         }
2933
2934         public function textFieldSize( $table, $field ) {
2935                 $table = $this->tableName( $table );
2936                 $sql = "SHOW COLUMNS FROM $table LIKE \"$field\"";
2937                 $res = $this->query( $sql, __METHOD__ );
2938                 $row = $this->fetchObject( $res );
2939
2940                 $m = [];
2941
2942                 if ( preg_match( '/\((.*)\)/', $row->Type, $m ) ) {
2943                         $size = $m[1];
2944                 } else {
2945                         $size = -1;
2946                 }
2947
2948                 return $size;
2949         }
2950
2951         public function delete( $table, $conds, $fname = __METHOD__ ) {
2952                 if ( !$conds ) {
2953                         throw new DBUnexpectedError( $this, __METHOD__ . ' called with no conditions' );
2954                 }
2955
2956                 $table = $this->tableName( $table );
2957                 $sql = "DELETE FROM $table";
2958
2959                 if ( $conds != '*' ) {
2960                         if ( is_array( $conds ) ) {
2961                                 $conds = $this->makeList( $conds, self::LIST_AND );
2962                         }
2963                         $sql .= ' WHERE ' . $conds;
2964                 }
2965
2966                 $this->query( $sql, $fname );
2967
2968                 return true;
2969         }
2970
2971         final public function insertSelect(
2972                 $destTable, $srcTable, $varMap, $conds,
2973                 $fname = __METHOD__, $insertOptions = [], $selectOptions = [], $selectJoinConds = []
2974         ) {
2975                 static $hints = [ 'NO_AUTO_COLUMNS' ];
2976
2977                 $insertOptions = (array)$insertOptions;
2978                 $selectOptions = (array)$selectOptions;
2979
2980                 if ( $this->cliMode && $this->isInsertSelectSafe( $insertOptions, $selectOptions ) ) {
2981                         // For massive migrations with downtime, we don't want to select everything
2982                         // into memory and OOM, so do all this native on the server side if possible.
2983                         $this->nativeInsertSelect(
2984                                 $destTable,
2985                                 $srcTable,
2986                                 $varMap,
2987                                 $conds,
2988                                 $fname,
2989                                 array_diff( $insertOptions, $hints ),
2990                                 $selectOptions,
2991                                 $selectJoinConds
2992                         );
2993                 } else {
2994                         $this->nonNativeInsertSelect(
2995                                 $destTable,
2996                                 $srcTable,
2997                                 $varMap,
2998                                 $conds,
2999                                 $fname,
3000                                 array_diff( $insertOptions, $hints ),
3001                                 $selectOptions,
3002                                 $selectJoinConds
3003                         );
3004                 }
3005
3006                 return true;
3007         }
3008
3009         /**
3010          * @param array $insertOptions INSERT options
3011          * @param array $selectOptions SELECT options
3012          * @return bool Whether an INSERT SELECT with these options will be replication safe
3013          * @since 1.31
3014          */
3015         protected function isInsertSelectSafe( array $insertOptions, array $selectOptions ) {
3016                 return true;
3017         }
3018
3019         /**
3020          * Implementation of insertSelect() based on select() and insert()
3021          *
3022          * @see IDatabase::insertSelect()
3023          * @since 1.30
3024          * @param string $destTable
3025          * @param string|array $srcTable
3026          * @param array $varMap
3027          * @param array $conds
3028          * @param string $fname
3029          * @param array $insertOptions
3030          * @param array $selectOptions
3031          * @param array $selectJoinConds
3032          */
3033         protected function nonNativeInsertSelect( $destTable, $srcTable, $varMap, $conds,
3034                 $fname = __METHOD__,
3035                 $insertOptions = [], $selectOptions = [], $selectJoinConds = []
3036         ) {
3037                 // For web requests, do a locking SELECT and then INSERT. This puts the SELECT burden
3038                 // on only the master (without needing row-based-replication). It also makes it easy to
3039                 // know how big the INSERT is going to be.
3040                 $fields = [];
3041                 foreach ( $varMap as $dstColumn => $sourceColumnOrSql ) {
3042                         $fields[] = $this->fieldNameWithAlias( $sourceColumnOrSql, $dstColumn );
3043                 }
3044                 $selectOptions[] = 'FOR UPDATE';
3045                 $res = $this->select(
3046                         $srcTable, implode( ',', $fields ), $conds, $fname, $selectOptions, $selectJoinConds
3047                 );
3048                 if ( !$res ) {
3049                         return;
3050                 }
3051
3052                 try {
3053                         $affectedRowCount = 0;
3054                         $this->startAtomic( $fname, self::ATOMIC_CANCELABLE );
3055                         $rows = [];
3056                         $ok = true;
3057                         foreach ( $res as $row ) {
3058                                 $rows[] = (array)$row;
3059
3060                                 // Avoid inserts that are too huge
3061                                 if ( count( $rows ) >= $this->nonNativeInsertSelectBatchSize ) {
3062                                         $ok = $this->insert( $destTable, $rows, $fname, $insertOptions );
3063                                         if ( !$ok ) {
3064                                                 break;
3065                                         }
3066                                         $affectedRowCount += $this->affectedRows();
3067                                         $rows = [];
3068                                 }
3069                         }
3070                         if ( $rows && $ok ) {
3071                                 $ok = $this->insert( $destTable, $rows, $fname, $insertOptions );
3072                                 if ( $ok ) {
3073                                         $affectedRowCount += $this->affectedRows();
3074                                 }
3075                         }
3076                         if ( $ok ) {
3077                                 $this->endAtomic( $fname );
3078                                 $this->affectedRowCount = $affectedRowCount;
3079                         } else {
3080                                 $this->cancelAtomic( $fname );
3081                         }
3082                 } catch ( Exception $e ) {
3083                         $this->cancelAtomic( $fname );
3084                         throw $e;
3085                 }
3086         }
3087
3088         /**
3089          * Native server-side implementation of insertSelect() for situations where
3090          * we don't want to select everything into memory
3091          *
3092          * @see IDatabase::insertSelect()
3093          * @param string $destTable
3094          * @param string|array $srcTable
3095          * @param array $varMap
3096          * @param array $conds
3097          * @param string $fname
3098          * @param array $insertOptions
3099          * @param array $selectOptions
3100          * @param array $selectJoinConds
3101          */
3102         protected function nativeInsertSelect( $destTable, $srcTable, $varMap, $conds,
3103                 $fname = __METHOD__,
3104                 $insertOptions = [], $selectOptions = [], $selectJoinConds = []
3105         ) {
3106                 $destTable = $this->tableName( $destTable );
3107
3108                 if ( !is_array( $insertOptions ) ) {
3109                         $insertOptions = [ $insertOptions ];
3110                 }
3111
3112                 $insertOptions = $this->makeInsertOptions( $insertOptions );
3113
3114                 $selectSql = $this->selectSQLText(
3115                         $srcTable,
3116                         array_values( $varMap ),
3117                         $conds,
3118                         $fname,
3119                         $selectOptions,
3120                         $selectJoinConds
3121                 );
3122
3123                 $sql = "INSERT $insertOptions" .
3124                         " INTO $destTable (" . implode( ',', array_keys( $varMap ) ) . ') ' .
3125                         $selectSql;
3126
3127                 $this->query( $sql, $fname );
3128         }
3129
3130         public function limitResult( $sql, $limit, $offset = false ) {
3131                 if ( !is_numeric( $limit ) ) {
3132                         throw new DBUnexpectedError( $this,
3133                                 "Invalid non-numeric limit passed to limitResult()\n" );
3134                 }
3135                 // This version works in MySQL and SQLite. It will very likely need to be
3136                 // overridden for most other RDBMS subclasses.
3137                 return "$sql LIMIT "
3138                         . ( ( is_numeric( $offset ) && $offset != 0 ) ? "{$offset}," : "" )
3139                         . "{$limit} ";
3140         }
3141
3142         public function unionSupportsOrderAndLimit() {
3143                 return true; // True for almost every DB supported
3144         }
3145
3146         public function unionQueries( $sqls, $all ) {
3147                 $glue = $all ? ') UNION ALL (' : ') UNION (';
3148
3149                 return '(' . implode( $glue, $sqls ) . ')';
3150         }
3151
3152         public function unionConditionPermutations(
3153                 $table, $vars, array $permute_conds, $extra_conds = '', $fname = __METHOD__,
3154                 $options = [], $join_conds = []
3155         ) {
3156                 // First, build the Cartesian product of $permute_conds
3157                 $conds = [ [] ];
3158                 foreach ( $permute_conds as $field => $values ) {
3159                         if ( !$values ) {
3160                                 // Skip empty $values
3161                                 continue;
3162                         }
3163                         $values = array_unique( $values ); // For sanity
3164                         $newConds = [];
3165                         foreach ( $conds as $cond ) {
3166                                 foreach ( $values as $value ) {
3167                                         $cond[$field] = $value;
3168                                         $newConds[] = $cond; // Arrays are by-value, not by-reference, so this works
3169                                 }
3170                         }
3171                         $conds = $newConds;
3172                 }
3173
3174                 $extra_conds = $extra_conds === '' ? [] : (array)$extra_conds;
3175
3176                 // If there's just one condition and no subordering, hand off to
3177                 // selectSQLText directly.
3178                 if ( count( $conds ) === 1 &&
3179                         ( !isset( $options['INNER ORDER BY'] ) || !$this->unionSupportsOrderAndLimit() )
3180                 ) {
3181                         return $this->selectSQLText(
3182                                 $table, $vars, $conds[0] + $extra_conds, $fname, $options, $join_conds
3183                         );
3184                 }
3185
3186                 // Otherwise, we need to pull out the order and limit to apply after
3187                 // the union. Then build the SQL queries for each set of conditions in
3188                 // $conds. Then union them together (using UNION ALL, because the
3189                 // product *should* already be distinct).
3190                 $orderBy = $this->makeOrderBy( $options );
3191                 $limit = $options['LIMIT'] ?? null;
3192                 $offset = $options['OFFSET'] ?? false;
3193                 $all = empty( $options['NOTALL'] ) && !in_array( 'NOTALL', $options );
3194                 if ( !$this->unionSupportsOrderAndLimit() ) {
3195                         unset( $options['ORDER BY'], $options['LIMIT'], $options['OFFSET'] );
3196                 } else {
3197                         if ( array_key_exists( 'INNER ORDER BY', $options ) ) {
3198                                 $options['ORDER BY'] = $options['INNER ORDER BY'];
3199                         }
3200                         if ( $limit !== null && is_numeric( $offset ) && $offset != 0 ) {
3201                                 // We need to increase the limit by the offset rather than
3202                                 // using the offset directly, otherwise it'll skip incorrectly
3203                                 // in the subqueries.
3204                                 $options['LIMIT'] = $limit + $offset;
3205                                 unset( $options['OFFSET'] );
3206                         }
3207                 }
3208
3209                 $sqls = [];
3210                 foreach ( $conds as $cond ) {
3211                         $sqls[] = $this->selectSQLText(
3212                                 $table, $vars, $cond + $extra_conds, $fname, $options, $join_conds
3213                         );
3214                 }
3215                 $sql = $this->unionQueries( $sqls, $all ) . $orderBy;
3216                 if ( $limit !== null ) {
3217                         $sql = $this->limitResult( $sql, $limit, $offset );
3218                 }
3219
3220                 return $sql;
3221         }
3222
3223         public function conditional( $cond, $trueVal, $falseVal ) {
3224                 if ( is_array( $cond ) ) {
3225                         $cond = $this->makeList( $cond, self::LIST_AND );
3226                 }
3227
3228                 return " (CASE WHEN $cond THEN $trueVal ELSE $falseVal END) ";
3229         }
3230
3231         public function strreplace( $orig, $old, $new ) {
3232                 return "REPLACE({$orig}, {$old}, {$new})";
3233         }
3234
3235         public function getServerUptime() {
3236                 return 0;
3237         }
3238
3239         public function wasDeadlock() {
3240                 return false;
3241         }
3242
3243         public function wasLockTimeout() {
3244                 return false;
3245         }
3246
3247         public function wasConnectionLoss() {
3248                 return $this->wasConnectionError( $this->lastErrno() );
3249         }
3250
3251         public function wasReadOnlyError() {
3252                 return false;
3253         }
3254
3255         public function wasErrorReissuable() {
3256                 return (
3257                         $this->wasDeadlock() ||
3258                         $this->wasLockTimeout() ||
3259                         $this->wasConnectionLoss()
3260                 );
3261         }
3262
3263         /**
3264          * Do not use this method outside of Database/DBError classes
3265          *
3266          * @param int|string $errno
3267          * @return bool Whether the given query error was a connection drop
3268          */
3269         public function wasConnectionError( $errno ) {
3270                 return false;
3271         }
3272
3273         /**
3274          * @return bool Whether it is known that the last query error only caused statement rollback
3275          * @note This is for backwards compatibility for callers catching DBError exceptions in
3276          *   order to ignore problems like duplicate key errors or foriegn key violations
3277          * @since 1.31
3278          */
3279         protected function wasKnownStatementRollbackError() {
3280                 return false; // don't know; it could have caused a transaction rollback
3281         }
3282
3283         public function deadlockLoop() {
3284                 $args = func_get_args();
3285                 $function = array_shift( $args );
3286                 $tries = self::$DEADLOCK_TRIES;
3287
3288                 $this->begin( __METHOD__ );
3289
3290                 $retVal = null;
3291                 /** @var Exception $e */
3292                 $e = null;
3293                 do {
3294                         try {
3295                                 $retVal = $function( ...$args );
3296                                 break;
3297                         } catch ( DBQueryError $e ) {
3298                                 if ( $this->wasDeadlock() ) {
3299                                         // Retry after a randomized delay
3300                                         usleep( mt_rand( self::$DEADLOCK_DELAY_MIN, self::$DEADLOCK_DELAY_MAX ) );
3301                                 } else {
3302                                         // Throw the error back up
3303                                         throw $e;
3304                                 }
3305                         }
3306                 } while ( --$tries > 0 );
3307
3308                 if ( $tries <= 0 ) {
3309                         // Too many deadlocks; give up
3310                         $this->rollback( __METHOD__ );
3311                         throw $e;
3312                 } else {
3313                         $this->commit( __METHOD__ );
3314
3315                         return $retVal;
3316                 }
3317         }
3318
3319         public function masterPosWait( DBMasterPos $pos, $timeout ) {
3320                 # Real waits are implemented in the subclass.
3321                 return 0;
3322         }
3323
3324         public function getReplicaPos() {
3325                 # Stub
3326                 return false;
3327         }
3328
3329         public function getMasterPos() {
3330                 # Stub
3331                 return false;
3332         }
3333
3334         public function serverIsReadOnly() {
3335                 return false;
3336         }
3337
3338         final public function onTransactionResolution( callable $callback, $fname = __METHOD__ ) {
3339                 if ( !$this->trxLevel ) {
3340                         throw new DBUnexpectedError( $this, "No transaction is active." );
3341                 }
3342                 $this->trxEndCallbacks[] = [ $callback, $fname, $this->currentAtomicSectionId() ];
3343         }
3344
3345         final public function onTransactionCommitOrIdle( callable $callback, $fname = __METHOD__ ) {
3346                 if ( !$this->trxLevel && $this->getTransactionRoundId() ) {
3347                         // Start an implicit transaction similar to how query() does
3348                         $this->begin( __METHOD__, self::TRANSACTION_INTERNAL );
3349                         $this->trxAutomatic = true;
3350                 }
3351
3352                 $this->trxIdleCallbacks[] = [ $callback, $fname, $this->currentAtomicSectionId() ];
3353                 if ( !$this->trxLevel ) {
3354                         $this->runOnTransactionIdleCallbacks( self::TRIGGER_IDLE );
3355                 }
3356         }
3357
3358         final public function onTransactionIdle( callable $callback, $fname = __METHOD__ ) {
3359                 $this->onTransactionCommitOrIdle( $callback, $fname );
3360         }
3361
3362         final public function onTransactionPreCommitOrIdle( callable $callback, $fname = __METHOD__ ) {
3363                 if ( !$this->trxLevel && $this->getTransactionRoundId() ) {
3364                         // Start an implicit transaction similar to how query() does
3365                         $this->begin( __METHOD__, self::TRANSACTION_INTERNAL );
3366                         $this->trxAutomatic = true;
3367                 }
3368
3369                 if ( $this->trxLevel ) {
3370                         $this->trxPreCommitCallbacks[] = [ $callback, $fname, $this->currentAtomicSectionId() ];
3371                 } else {
3372                         // No transaction is active nor will start implicitly, so make one for this callback
3373                         $this->startAtomic( __METHOD__, self::ATOMIC_CANCELABLE );
3374                         try {
3375                                 $callback( $this );
3376                                 $this->endAtomic( __METHOD__ );
3377                         } catch ( Exception $e ) {
3378                                 $this->cancelAtomic( __METHOD__ );
3379                                 throw $e;
3380                         }
3381                 }
3382         }
3383
3384         final public function onAtomicSectionCancel( callable $callback, $fname = __METHOD__ ) {
3385                 if ( !$this->trxLevel || !$this->trxAtomicLevels ) {
3386                         throw new DBUnexpectedError( $this, "No atomic section is open (got $fname)." );
3387                 }
3388                 $this->trxSectionCancelCallbacks[] = [ $callback, $fname, $this->currentAtomicSectionId() ];
3389         }
3390
3391         /**
3392          * @return AtomicSectionIdentifier|null ID of the topmost atomic section level
3393          */
3394         private function currentAtomicSectionId() {
3395                 if ( $this->trxLevel && $this->trxAtomicLevels ) {
3396                         $levelInfo = end( $this->trxAtomicLevels );
3397
3398                         return $levelInfo[1];
3399                 }
3400
3401                 return null;
3402         }
3403
3404         /**
3405          * Hoist callback ownership for callbacks in a section to a parent section.
3406          * All callbacks should have an owner that is present in trxAtomicLevels.
3407          * @param AtomicSectionIdentifier $old
3408          * @param AtomicSectionIdentifier $new
3409          */
3410         private function reassignCallbacksForSection(
3411                 AtomicSectionIdentifier $old, AtomicSectionIdentifier $new
3412         ) {
3413                 foreach ( $this->trxPreCommitCallbacks as $key => $info ) {
3414                         if ( $info[2] === $old ) {
3415                                 $this->trxPreCommitCallbacks[$key][2] = $new;
3416                         }
3417                 }
3418                 foreach ( $this->trxIdleCallbacks as $key => $info ) {
3419                         if ( $info[2] === $old ) {
3420                                 $this->trxIdleCallbacks[$key][2] = $new;
3421                         }
3422                 }
3423                 foreach ( $this->trxEndCallbacks as $key => $info ) {
3424                         if ( $info[2] === $old ) {
3425                                 $this->trxEndCallbacks[$key][2] = $new;
3426                         }
3427                 }
3428                 foreach ( $this->trxSectionCancelCallbacks as $key => $info ) {
3429                         if ( $info[2] === $old ) {
3430                                 $this->trxSectionCancelCallbacks[$key][2] = $new;
3431                         }
3432                 }
3433         }
3434
3435         /**
3436          * Update callbacks that were owned by cancelled atomic sections.
3437          *
3438          * Callbacks for "on commit" should never be run if they're owned by a
3439          * section that won't be committed.
3440          *
3441          * Callbacks for "on resolution" need to reflect that the section was
3442          * rolled back, even if the transaction as a whole commits successfully.
3443          *
3444          * Callbacks for "on section cancel" should already have been consumed,
3445          * but errors during the cancellation itself can prevent that while still
3446          * destroying the section. Hoist any such callbacks to the new top section,
3447          * which we assume will itself have to be cancelled or rolled back to
3448          * resolve the error.
3449          *
3450          * @param AtomicSectionIdentifier[] $sectionIds ID of an actual savepoint
3451          * @param AtomicSectionIdentifier|null $newSectionId New top section ID.
3452          * @throws UnexpectedValueException
3453          */
3454         private function modifyCallbacksForCancel(
3455                 array $sectionIds, AtomicSectionIdentifier $newSectionId = null
3456         ) {
3457                 // Cancel the "on commit" callbacks owned by this savepoint
3458                 $this->trxIdleCallbacks = array_filter(
3459                         $this->trxIdleCallbacks,
3460                         function ( $entry ) use ( $sectionIds ) {
3461                                 return !in_array( $entry[2], $sectionIds, true );
3462                         }
3463                 );
3464                 $this->trxPreCommitCallbacks = array_filter(
3465                         $this->trxPreCommitCallbacks,
3466                         function ( $entry ) use ( $sectionIds ) {
3467                                 return !in_array( $entry[2], $sectionIds, true );
3468                         }
3469                 );
3470                 // Make "on resolution" callbacks owned by this savepoint to perceive a rollback
3471                 foreach ( $this->trxEndCallbacks as $key => $entry ) {
3472                         if ( in_array( $entry[2], $sectionIds, true ) ) {
3473                                 $callback = $entry[0];
3474                                 $this->trxEndCallbacks[$key][0] = function () use ( $callback ) {
3475                                         // @phan-suppress-next-line PhanInfiniteRecursion No recursion at all here, phan is confused
3476                                         return $callback( self::TRIGGER_ROLLBACK, $this );
3477                                 };
3478                                 // This "on resolution" callback no longer belongs to a section.
3479                                 $this->trxEndCallbacks[$key][2] = null;
3480                         }
3481                 }
3482                 // Hoist callback ownership for section cancel callbacks to the new top section
3483                 foreach ( $this->trxSectionCancelCallbacks as $key => $entry ) {
3484                         if ( in_array( $entry[2], $sectionIds, true ) ) {
3485                                 $this->trxSectionCancelCallbacks[$key][2] = $newSectionId;
3486                         }
3487                 }
3488         }
3489
3490         final public function setTransactionListener( $name, callable $callback = null ) {
3491                 if ( $callback ) {
3492                         $this->trxRecurringCallbacks[$name] = $callback;
3493                 } else {
3494                         unset( $this->trxRecurringCallbacks[$name] );
3495                 }
3496         }
3497
3498         /**
3499          * Whether to disable running of post-COMMIT/ROLLBACK callbacks
3500          *
3501          * This method should not be used outside of Database/LoadBalancer
3502          *
3503          * @param bool $suppress
3504          * @since 1.28
3505          */
3506         final public function setTrxEndCallbackSuppression( $suppress ) {
3507                 $this->trxEndCallbacksSuppressed = $suppress;
3508         }
3509
3510         /**
3511          * Actually consume and run any "on transaction idle/resolution" callbacks.
3512          *
3513          * This method should not be used outside of Database/LoadBalancer
3514          *
3515          * @param int $trigger IDatabase::TRIGGER_* constant
3516          * @return int Number of callbacks attempted
3517          * @since 1.20
3518          * @throws Exception
3519          */
3520         public function runOnTransactionIdleCallbacks( $trigger ) {
3521                 if ( $this->trxLevel ) { // sanity
3522                         throw new DBUnexpectedError( $this, __METHOD__ . ': a transaction is still open.' );
3523                 }
3524
3525                 if ( $this->trxEndCallbacksSuppressed ) {
3526                         return 0;
3527                 }
3528
3529                 $count = 0;
3530                 $autoTrx = $this->getFlag( self::DBO_TRX ); // automatic begin() enabled?
3531                 /** @var Exception $e */
3532                 $e = null; // first exception
3533                 do { // callbacks may add callbacks :)
3534                         $callbacks = array_merge(
3535                                 $this->trxIdleCallbacks,
3536                                 $this->trxEndCallbacks // include "transaction resolution" callbacks
3537                         );
3538                         $this->trxIdleCallbacks = []; // consumed (and recursion guard)
3539                         $this->trxEndCallbacks = []; // consumed (recursion guard)
3540
3541                         // Only run trxSectionCancelCallbacks on rollback, not commit.
3542                         // But always consume them.
3543                         if ( $trigger === self::TRIGGER_ROLLBACK ) {
3544                                 $callbacks = array_merge( $callbacks, $this->trxSectionCancelCallbacks );
3545                         }
3546                         $this->trxSectionCancelCallbacks = []; // consumed (recursion guard)
3547
3548                         foreach ( $callbacks as $callback ) {
3549                                 ++$count;
3550                                 list( $phpCallback ) = $callback;
3551                                 $this->clearFlag( self::DBO_TRX ); // make each query its own transaction
3552                                 try {
3553                                         // @phan-suppress-next-line PhanParamTooManyCallable
3554                                         call_user_func( $phpCallback, $trigger, $this );
3555                                 } catch ( Exception $ex ) {
3556                                         call_user_func( $this->errorLogger, $ex );
3557                                         $e = $e ?: $ex;
3558                                         // Some callbacks may use startAtomic/endAtomic, so make sure
3559                                         // their transactions are ended so other callbacks don't fail
3560                                         if ( $this->trxLevel() ) {
3561                                                 $this->rollback( __METHOD__, self::FLUSHING_INTERNAL );
3562                                         }
3563                                 } finally {
3564                                         if ( $autoTrx ) {
3565                                                 $this->setFlag( self::DBO_TRX ); // restore automatic begin()
3566                                         } else {
3567                                                 $this->clearFlag( self::DBO_TRX ); // restore auto-commit
3568                                         }
3569                                 }
3570                         }
3571                 } while ( count( $this->trxIdleCallbacks ) );
3572
3573                 if ( $e instanceof Exception ) {
3574                         throw $e; // re-throw any first exception
3575                 }
3576
3577                 return $count;
3578         }
3579
3580         /**
3581          * Actually consume and run any "on transaction pre-commit" callbacks.
3582          *
3583          * This method should not be used outside of Database/LoadBalancer
3584          *
3585          * @since 1.22
3586          * @return int Number of callbacks attempted
3587          * @throws Exception
3588          */
3589         public function runOnTransactionPreCommitCallbacks() {
3590                 $count = 0;
3591
3592                 $e = null; // first exception
3593                 do { // callbacks may add callbacks :)
3594                         $callbacks = $this->trxPreCommitCallbacks;
3595                         $this->trxPreCommitCallbacks = []; // consumed (and recursion guard)
3596                         foreach ( $callbacks as $callback ) {
3597                                 try {
3598                                         ++$count;
3599                                         list( $phpCallback ) = $callback;
3600                                         $phpCallback( $this );
3601                                 } catch ( Exception $ex ) {
3602                                         ( $this->errorLogger )( $ex );
3603                                         $e = $e ?: $ex;
3604                                 }
3605                         }
3606                 } while ( count( $this->trxPreCommitCallbacks ) );
3607
3608                 if ( $e instanceof Exception ) {
3609                         throw $e; // re-throw any first exception
3610                 }
3611
3612                 return $count;
3613         }
3614
3615         /**
3616          * Actually run any "atomic section cancel" callbacks.
3617          *
3618          * @param int $trigger IDatabase::TRIGGER_* constant
3619          * @param AtomicSectionIdentifier[]|null $sectionId Section IDs to cancel,
3620          *  null on transaction rollback
3621          */
3622         private function runOnAtomicSectionCancelCallbacks(
3623                 $trigger, array $sectionIds = null
3624         ) {
3625                 /** @var Exception|Throwable $e */
3626                 $e = null; // first exception
3627
3628                 $notCancelled = [];
3629                 do {
3630                         $callbacks = $this->trxSectionCancelCallbacks;
3631                         $this->trxSectionCancelCallbacks = []; // consumed (recursion guard)
3632                         foreach ( $callbacks as $entry ) {
3633                                 if ( $sectionIds === null || in_array( $entry[2], $sectionIds, true ) ) {
3634                                         try {
3635                                                 $entry[0]( $trigger, $this );
3636                                         } catch ( Exception $ex ) {
3637                                                 ( $this->errorLogger )( $ex );
3638                                                 $e = $e ?: $ex;
3639                                         } catch ( Throwable $ex ) {
3640                                                 // @todo: Log?
3641                                                 $e = $e ?: $ex;
3642                                         }
3643                                 } else {
3644                                         $notCancelled[] = $entry;
3645                                 }
3646                         }
3647                 } while ( count( $this->trxSectionCancelCallbacks ) );
3648                 $this->trxSectionCancelCallbacks = $notCancelled;
3649
3650                 if ( $e !== null ) {
3651                         throw $e; // re-throw any first Exception/Throwable
3652                 }
3653         }
3654
3655         /**
3656          * Actually run any "transaction listener" callbacks.
3657          *
3658          * This method should not be used outside of Database/LoadBalancer
3659          *
3660          * @param int $trigger IDatabase::TRIGGER_* constant
3661          * @throws Exception
3662          * @since 1.20
3663          */
3664         public function runTransactionListenerCallbacks( $trigger ) {
3665                 if ( $this->trxEndCallbacksSuppressed ) {
3666                         return;
3667                 }
3668
3669                 /** @var Exception $e */
3670                 $e = null; // first exception
3671
3672                 foreach ( $this->trxRecurringCallbacks as $phpCallback ) {
3673                         try {
3674                                 $phpCallback( $trigger, $this );
3675                         } catch ( Exception $ex ) {
3676                                 ( $this->errorLogger )( $ex );
3677                                 $e = $e ?: $ex;
3678                         }
3679                 }
3680
3681                 if ( $e instanceof Exception ) {
3682                         throw $e; // re-throw any first exception
3683                 }
3684         }
3685
3686         /**
3687          * Create a savepoint
3688          *
3689          * This is used internally to implement atomic sections. It should not be
3690          * used otherwise.
3691          *
3692          * @since 1.31
3693          * @param string $identifier Identifier for the savepoint
3694          * @param string $fname Calling function name
3695          */
3696         protected function doSavepoint( $identifier, $fname ) {
3697                 $this->query( 'SAVEPOINT ' . $this->addIdentifierQuotes( $identifier ), $fname );
3698         }
3699
3700         /**
3701          * Release a savepoint
3702          *
3703          * This is used internally to implement atomic sections. It should not be
3704          * used otherwise.
3705          *
3706          * @since 1.31
3707          * @param string $identifier Identifier for the savepoint
3708          * @param string $fname Calling function name
3709          */
3710         protected function doReleaseSavepoint( $identifier, $fname ) {
3711                 $this->query( 'RELEASE SAVEPOINT ' . $this->addIdentifierQuotes( $identifier ), $fname );
3712         }
3713
3714         /**
3715          * Rollback to a savepoint
3716          *
3717          * This is used internally to implement atomic sections. It should not be
3718          * used otherwise.
3719          *
3720          * @since 1.31
3721          * @param string $identifier Identifier for the savepoint
3722          * @param string $fname Calling function name
3723          */
3724         protected function doRollbackToSavepoint( $identifier, $fname ) {
3725                 $this->query( 'ROLLBACK TO SAVEPOINT ' . $this->addIdentifierQuotes( $identifier ), $fname );
3726         }
3727
3728         /**
3729          * @param string $fname
3730          * @return string
3731          */
3732         private function nextSavepointId( $fname ) {
3733                 $savepointId = self::$SAVEPOINT_PREFIX . ++$this->trxAtomicCounter;
3734                 if ( strlen( $savepointId ) > 30 ) {
3735                         // 30 == Oracle's identifier length limit (pre 12c)
3736                         // With a 22 character prefix, that puts the highest number at 99999999.
3737                         throw new DBUnexpectedError(
3738                                 $this,
3739                                 'There have been an excessively large number of atomic sections in a transaction'
3740                                 . " started by $this->trxFname (at $fname)"
3741                         );
3742                 }
3743
3744                 return $savepointId;
3745         }
3746
3747         final public function startAtomic(
3748                 $fname = __METHOD__, $cancelable = self::ATOMIC_NOT_CANCELABLE
3749         ) {
3750                 $savepointId = $cancelable === self::ATOMIC_CANCELABLE ? self::$NOT_APPLICABLE : null;
3751
3752                 if ( !$this->trxLevel ) {
3753                         $this->begin( $fname, self::TRANSACTION_INTERNAL ); // sets trxAutomatic
3754                         // If DBO_TRX is set, a series of startAtomic/endAtomic pairs will result
3755                         // in all changes being in one transaction to keep requests transactional.
3756                         if ( $this->getFlag( self::DBO_TRX ) ) {
3757                                 // Since writes could happen in between the topmost atomic sections as part
3758                                 // of the transaction, those sections will need savepoints.
3759                                 $savepointId = $this->nextSavepointId( $fname );
3760                                 $this->doSavepoint( $savepointId, $fname );
3761                         } else {
3762                                 $this->trxAutomaticAtomic = true;
3763                         }
3764                 } elseif ( $cancelable === self::ATOMIC_CANCELABLE ) {
3765                         $savepointId = $this->nextSavepointId( $fname );
3766                         $this->doSavepoint( $savepointId, $fname );
3767                 }
3768
3769                 $sectionId = new AtomicSectionIdentifier;
3770                 $this->trxAtomicLevels[] = [ $fname, $sectionId, $savepointId ];
3771                 $this->queryLogger->debug( 'startAtomic: entering level ' .
3772                         ( count( $this->trxAtomicLevels ) - 1 ) . " ($fname)" );
3773
3774                 return $sectionId;
3775         }
3776
3777         final public function endAtomic( $fname = __METHOD__ ) {
3778                 if ( !$this->trxLevel || !$this->trxAtomicLevels ) {
3779                         throw new DBUnexpectedError( $this, "No atomic section is open (got $fname)." );
3780                 }
3781
3782                 // Check if the current section matches $fname
3783                 $pos = count( $this->trxAtomicLevels ) - 1;
3784                 list( $savedFname, $sectionId, $savepointId ) = $this->trxAtomicLevels[$pos];
3785                 $this->queryLogger->debug( "endAtomic: leaving level $pos ($fname)" );
3786
3787                 if ( $savedFname !== $fname ) {
3788                         throw new DBUnexpectedError(
3789                                 $this,
3790                                 "Invalid atomic section ended (got $fname but expected $savedFname)."
3791                         );
3792                 }
3793
3794                 // Remove the last section (no need to re-index the array)
3795                 array_pop( $this->trxAtomicLevels );
3796
3797                 if ( !$this->trxAtomicLevels && $this->trxAutomaticAtomic ) {
3798                         $this->commit( $fname, self::FLUSHING_INTERNAL );
3799                 } elseif ( $savepointId !== null && $savepointId !== self::$NOT_APPLICABLE ) {
3800                         $this->doReleaseSavepoint( $savepointId, $fname );
3801                 }
3802
3803                 // Hoist callback ownership for callbacks in the section that just ended;
3804                 // all callbacks should have an owner that is present in trxAtomicLevels.
3805                 $currentSectionId = $this->currentAtomicSectionId();
3806                 if ( $currentSectionId ) {
3807                         $this->reassignCallbacksForSection( $sectionId, $currentSectionId );
3808                 }
3809         }
3810
3811         final public function cancelAtomic(
3812                 $fname = __METHOD__, AtomicSectionIdentifier $sectionId = null
3813         ) {
3814                 if ( !$this->trxLevel || !$this->trxAtomicLevels ) {
3815                         throw new DBUnexpectedError( $this, "No atomic section is open (got $fname)." );
3816                 }
3817
3818                 $excisedIds = [];
3819                 $newTopSection = $this->currentAtomicSectionId();
3820                 try {
3821                         $excisedFnames = [];
3822                         if ( $sectionId !== null ) {
3823                                 // Find the (last) section with the given $sectionId
3824                                 $pos = -1;
3825                                 foreach ( $this->trxAtomicLevels as $i => list( $asFname, $asId, $spId ) ) {
3826                                         if ( $asId === $sectionId ) {
3827                                                 $pos = $i;
3828                                         }
3829                                 }
3830                                 if ( $pos < 0 ) {
3831                                         throw new DBUnexpectedError( $this, "Atomic section not found (for $fname)" );
3832                                 }
3833                                 // Remove all descendant sections and re-index the array
3834                                 $len = count( $this->trxAtomicLevels );
3835                                 for ( $i = $pos + 1; $i < $len; ++$i ) {
3836                                         $excisedFnames[] = $this->trxAtomicLevels[$i][0];
3837                                         $excisedIds[] = $this->trxAtomicLevels[$i][1];
3838                                 }
3839                                 $this->trxAtomicLevels = array_slice( $this->trxAtomicLevels, 0, $pos + 1 );
3840                                 $newTopSection = $this->currentAtomicSectionId();
3841                         }
3842
3843                         // Check if the current section matches $fname
3844                         $pos = count( $this->trxAtomicLevels ) - 1;
3845                         list( $savedFname, $savedSectionId, $savepointId ) = $this->trxAtomicLevels[$pos];
3846
3847                         if ( $excisedFnames ) {
3848                                 $this->queryLogger->debug( "cancelAtomic: canceling level $pos ($savedFname) " .
3849                                         "and descendants " . implode( ', ', $excisedFnames ) );
3850                         } else {
3851                                 $this->queryLogger->debug( "cancelAtomic: canceling level $pos ($savedFname)" );
3852                         }
3853
3854                         if ( $savedFname !== $fname ) {
3855                                 throw new DBUnexpectedError(
3856                                         $this,
3857                                         "Invalid atomic section ended (got $fname but expected $savedFname)."
3858                                 );
3859                         }
3860
3861                         // Remove the last section (no need to re-index the array)
3862                         array_pop( $this->trxAtomicLevels );
3863                         $excisedIds[] = $savedSectionId;
3864                         $newTopSection = $this->currentAtomicSectionId();
3865
3866                         if ( $savepointId !== null ) {
3867                                 // Rollback the transaction to the state just before this atomic section
3868                                 if ( $savepointId === self::$NOT_APPLICABLE ) {
3869                                         $this->rollback( $fname, self::FLUSHING_INTERNAL );
3870                                         // Note: rollback() will run trxSectionCancelCallbacks
3871                                 } else {
3872                                         $this->doRollbackToSavepoint( $savepointId, $fname );
3873                                         $this->trxStatus = self::STATUS_TRX_OK; // no exception; recovered
3874                                         $this->trxStatusIgnoredCause = null;
3875
3876                                         // Run trxSectionCancelCallbacks now.
3877                                         $this->runOnAtomicSectionCancelCallbacks( self::TRIGGER_CANCEL, $excisedIds );
3878                                 }
3879                         } elseif ( $this->trxStatus > self::STATUS_TRX_ERROR ) {
3880                                 // Put the transaction into an error state if it's not already in one
3881                                 $this->trxStatus = self::STATUS_TRX_ERROR;
3882                                 $this->trxStatusCause = new DBUnexpectedError(
3883                                         $this,
3884                                         "Uncancelable atomic section canceled (got $fname)."
3885                                 );
3886                         }
3887                 } finally {
3888                         // Fix up callbacks owned by the sections that were just cancelled.
3889                         // All callbacks should have an owner that is present in trxAtomicLevels.
3890                         $this->modifyCallbacksForCancel( $excisedIds, $newTopSection );
3891                 }
3892
3893                 $this->affectedRowCount = 0; // for the sake of consistency
3894         }
3895
3896         final public function doAtomicSection(
3897                 $fname, callable $callback, $cancelable = self::ATOMIC_NOT_CANCELABLE
3898         ) {
3899                 $sectionId = $this->startAtomic( $fname, $cancelable );
3900                 try {
3901                         $res = $callback( $this, $fname );
3902                 } catch ( Exception $e ) {
3903                         $this->cancelAtomic( $fname, $sectionId );
3904
3905                         throw $e;
3906                 }
3907                 $this->endAtomic( $fname );
3908
3909                 return $res;
3910         }
3911
3912         final public function begin( $fname = __METHOD__, $mode = self::TRANSACTION_EXPLICIT ) {
3913                 static $modes = [ self::TRANSACTION_EXPLICIT, self::TRANSACTION_INTERNAL ];
3914                 if ( !in_array( $mode, $modes, true ) ) {
3915                         throw new DBUnexpectedError( $this, "$fname: invalid mode parameter '$mode'." );
3916                 }
3917
3918                 // Protect against mismatched atomic section, transaction nesting, and snapshot loss
3919                 if ( $this->trxLevel ) {
3920                         if ( $this->trxAtomicLevels ) {
3921                                 $levels = $this->flatAtomicSectionList();
3922                                 $msg = "$fname: Got explicit BEGIN while atomic section(s) $levels are open.";
3923                                 throw new DBUnexpectedError( $this, $msg );
3924                         } elseif ( !$this->trxAutomatic ) {
3925                                 $msg = "$fname: Explicit transaction already active (from {$this->trxFname}).";
3926                                 throw new DBUnexpectedError( $this, $msg );
3927                         } else {
3928                                 $msg = "$fname: Implicit transaction already active (from {$this->trxFname}).";
3929                                 throw new DBUnexpectedError( $this, $msg );
3930                         }
3931                 } elseif ( $this->getFlag( self::DBO_TRX ) && $mode !== self::TRANSACTION_INTERNAL ) {
3932                         $msg = "$fname: Implicit transaction expected (DBO_TRX set).";
3933                         throw new DBUnexpectedError( $this, $msg );
3934                 }
3935
3936                 $this->assertHasConnectionHandle();
3937
3938                 $this->doBegin( $fname );
3939                 $this->trxStatus = self::STATUS_TRX_OK;
3940                 $this->trxStatusIgnoredCause = null;
3941                 $this->trxAtomicCounter = 0;
3942                 $this->trxTimestamp = microtime( true );
3943                 $this->trxFname = $fname;
3944                 $this->trxDoneWrites = false;
3945                 $this->trxAutomaticAtomic = false;
3946                 $this->trxAtomicLevels = [];
3947                 $this->trxShortId = sprintf( '%06x', mt_rand( 0, 0xffffff ) );
3948                 $this->trxWriteDuration = 0.0;
3949                 $this->trxWriteQueryCount = 0;
3950                 $this->trxWriteAffectedRows = 0;
3951                 $this->trxWriteAdjDuration = 0.0;
3952                 $this->trxWriteAdjQueryCount = 0;
3953                 $this->trxWriteCallers = [];
3954                 // First SELECT after BEGIN will establish the snapshot in REPEATABLE-READ.
3955                 // Get an estimate of the replication lag before any such queries.
3956                 $this->trxReplicaLag = null; // clear cached value first
3957                 $this->trxReplicaLag = $this->getApproximateLagStatus()['lag'];
3958                 // T147697: make explicitTrxActive() return true until begin() finishes. This way, no
3959                 // caller will think its OK to muck around with the transaction just because startAtomic()
3960                 // has not yet completed (e.g. setting trxAtomicLevels).
3961                 $this->trxAutomatic = ( $mode === self::TRANSACTION_INTERNAL );
3962         }
3963
3964         /**
3965          * Issues the BEGIN command to the database server.
3966          *
3967          * @see Database::begin()
3968          * @param string $fname
3969          */
3970         protected function doBegin( $fname ) {
3971                 $this->query( 'BEGIN', $fname );
3972                 $this->trxLevel = 1;
3973         }
3974
3975         final public function commit( $fname = __METHOD__, $flush = self::FLUSHING_ONE ) {
3976                 static $modes = [ self::FLUSHING_ONE, self::FLUSHING_ALL_PEERS, self::FLUSHING_INTERNAL ];
3977                 if ( !in_array( $flush, $modes, true ) ) {
3978                         throw new DBUnexpectedError( $this, "$fname: invalid flush parameter '$flush'." );
3979                 }
3980
3981                 if ( $this->trxLevel && $this->trxAtomicLevels ) {
3982                         // There are still atomic sections open; this cannot be ignored
3983                         $levels = $this->flatAtomicSectionList();
3984                         throw new DBUnexpectedError(
3985                                 $this,
3986                                 "$fname: Got COMMIT while atomic sections $levels are still open."
3987                         );
3988                 }
3989
3990                 if ( $flush === self::FLUSHING_INTERNAL || $flush === self::FLUSHING_ALL_PEERS ) {
3991                         if ( !$this->trxLevel ) {
3992                                 return; // nothing to do
3993                         } elseif ( !$this->trxAutomatic ) {
3994                                 throw new DBUnexpectedError(
3995                                         $this,
3996                                         "$fname: Flushing an explicit transaction, getting out of sync."
3997                                 );
3998                         }
3999                 } elseif ( !$this->trxLevel ) {
4000                         $this->queryLogger->error(
4001                                 "$fname: No transaction to commit, something got out of sync." );
4002                         return; // nothing to do
4003                 } elseif ( $this->trxAutomatic ) {
4004                         throw new DBUnexpectedError(
4005                                 $this,
4006                                 "$fname: Expected mass commit of all peer transactions (DBO_TRX set)."
4007                         );
4008                 }
4009
4010                 $this->assertHasConnectionHandle();
4011
4012                 $this->runOnTransactionPreCommitCallbacks();
4013
4014                 $writeTime = $this->pendingWriteQueryDuration( self::ESTIMATE_DB_APPLY );
4015                 $this->doCommit( $fname );
4016                 $this->trxStatus = self::STATUS_TRX_NONE;
4017
4018                 if ( $this->trxDoneWrites ) {
4019                         $this->lastWriteTime = microtime( true );
4020                         $this->trxProfiler->transactionWritingOut(
4021                                 $this->server,
4022                                 $this->getDomainID(),
4023                                 $this->trxShortId,
4024                                 $writeTime,
4025                                 $this->trxWriteAffectedRows
4026                         );
4027                 }
4028
4029                 // With FLUSHING_ALL_PEERS, callbacks will be explicitly run later
4030                 if ( $flush !== self::FLUSHING_ALL_PEERS ) {
4031                         $this->runOnTransactionIdleCallbacks( self::TRIGGER_COMMIT );
4032                         $this->runTransactionListenerCallbacks( self::TRIGGER_COMMIT );
4033                 }
4034         }
4035
4036         /**
4037          * Issues the COMMIT command to the database server.
4038          *
4039          * @see Database::commit()
4040          * @param string $fname
4041          */
4042         protected function doCommit( $fname ) {
4043                 if ( $this->trxLevel ) {
4044                         $this->query( 'COMMIT', $fname );
4045                         $this->trxLevel = 0;
4046                 }
4047         }
4048
4049         final public function rollback( $fname = __METHOD__, $flush = self::FLUSHING_ONE ) {
4050                 $trxActive = $this->trxLevel;
4051
4052                 if ( $flush !== self::FLUSHING_INTERNAL
4053                         && $flush !== self::FLUSHING_ALL_PEERS
4054                         && $this->getFlag( self::DBO_TRX )
4055                 ) {
4056                         throw new DBUnexpectedError(
4057                                 $this,
4058                                 "$fname: Expected mass rollback of all peer transactions (DBO_TRX set)."
4059                         );
4060                 }
4061
4062                 if ( $trxActive ) {
4063                         $this->assertHasConnectionHandle();
4064
4065                         $this->doRollback( $fname );
4066                         $this->trxStatus = self::STATUS_TRX_NONE;
4067                         $this->trxAtomicLevels = [];
4068                         // Estimate the RTT via a query now that trxStatus is OK
4069                         $writeTime = $this->pingAndCalculateLastTrxApplyTime();
4070
4071                         if ( $this->trxDoneWrites ) {
4072                                 $this->trxProfiler->transactionWritingOut(
4073                                         $this->server,
4074                                         $this->getDomainID(),
4075                                         $this->trxShortId,
4076                                         $writeTime,
4077                                         $this->trxWriteAffectedRows
4078                                 );
4079                         }
4080                 }
4081
4082                 // Clear any commit-dependant callbacks. They might even be present
4083                 // only due to transaction rounds, with no SQL transaction being active
4084                 $this->trxIdleCallbacks = [];
4085                 $this->trxPreCommitCallbacks = [];
4086
4087                 // With FLUSHING_ALL_PEERS, callbacks will be explicitly run later
4088                 if ( $trxActive && $flush !== self::FLUSHING_ALL_PEERS ) {
4089                         try {
4090                                 $this->runOnTransactionIdleCallbacks( self::TRIGGER_ROLLBACK );
4091                         } catch ( Exception $e ) {
4092                                 // already logged; finish and let LoadBalancer move on during mass-rollback
4093                         }
4094                         try {
4095                                 $this->runTransactionListenerCallbacks( self::TRIGGER_ROLLBACK );
4096                         } catch ( Exception $e ) {
4097                                 // already logged; let LoadBalancer move on during mass-rollback
4098                         }
4099
4100                         $this->affectedRowCount = 0; // for the sake of consistency
4101                 }
4102         }
4103
4104         /**
4105          * Issues the ROLLBACK command to the database server.
4106          *
4107          * @see Database::rollback()
4108          * @param string $fname
4109          */
4110         protected function doRollback( $fname ) {
4111                 if ( $this->trxLevel ) {
4112                         # Disconnects cause rollback anyway, so ignore those errors
4113                         $ignoreErrors = true;
4114                         $this->query( 'ROLLBACK', $fname, $ignoreErrors );
4115                         $this->trxLevel = 0;
4116                 }
4117         }
4118
4119         public function flushSnapshot( $fname = __METHOD__ ) {
4120                 if ( $this->writesOrCallbacksPending() || $this->explicitTrxActive() ) {
4121                         // This only flushes transactions to clear snapshots, not to write data
4122                         $fnames = implode( ', ', $this->pendingWriteAndCallbackCallers() );
4123                         throw new DBUnexpectedError(
4124                                 $this,
4125                                 "$fname: Cannot flush snapshot because writes are pending ($fnames)."
4126                         );
4127                 }
4128
4129                 $this->commit( $fname, self::FLUSHING_INTERNAL );
4130         }
4131
4132         public function explicitTrxActive() {
4133                 return $this->trxLevel && ( $this->trxAtomicLevels || !$this->trxAutomatic );
4134         }
4135
4136         public function duplicateTableStructure(
4137                 $oldName, $newName, $temporary = false, $fname = __METHOD__
4138         ) {
4139                 throw new RuntimeException( __METHOD__ . ' is not implemented in descendant class' );
4140         }
4141
4142         public function listTables( $prefix = null, $fname = __METHOD__ ) {
4143                 throw new RuntimeException( __METHOD__ . ' is not implemented in descendant class' );
4144         }
4145
4146         public function listViews( $prefix = null, $fname = __METHOD__ ) {
4147                 throw new RuntimeException( __METHOD__ . ' is not implemented in descendant class' );
4148         }
4149
4150         public function timestamp( $ts = 0 ) {
4151                 $t = new ConvertibleTimestamp( $ts );
4152                 // Let errors bubble up to avoid putting garbage in the DB
4153                 return $t->getTimestamp( TS_MW );
4154         }
4155
4156         public function timestampOrNull( $ts = null ) {
4157                 if ( is_null( $ts ) ) {
4158                         return null;
4159                 } else {
4160                         return $this->timestamp( $ts );
4161                 }
4162         }
4163
4164         public function affectedRows() {
4165                 return ( $this->affectedRowCount === null )
4166                         ? $this->fetchAffectedRowCount() // default to driver value
4167                         : $this->affectedRowCount;
4168         }
4169
4170         /**
4171          * @return int Number of retrieved rows according to the driver
4172          */
4173         abstract protected function fetchAffectedRowCount();
4174
4175         /**
4176          * Take the result from a query, and wrap it in a ResultWrapper if
4177          * necessary. Boolean values are passed through as is, to indicate success
4178          * of write queries or failure.
4179          *
4180          * Once upon a time, Database::query() returned a bare MySQL result
4181          * resource, and it was necessary to call this function to convert it to
4182          * a wrapper. Nowadays, raw database objects are never exposed to external
4183          * callers, so this is unnecessary in external code.
4184          *
4185          * @param bool|IResultWrapper|resource $result
4186          * @return bool|IResultWrapper
4187          */
4188         protected function resultObject( $result ) {
4189                 if ( !$result ) {
4190                         return false;
4191                 } elseif ( $result instanceof ResultWrapper ) {
4192                         return $result;
4193                 } elseif ( $result === true ) {
4194                         // Successful write query
4195                         return $result;
4196                 } else {
4197                         return new ResultWrapper( $this, $result );
4198                 }
4199         }
4200
4201         public function ping( &$rtt = null ) {
4202                 // Avoid hitting the server if it was hit recently
4203                 if ( $this->isOpen() && ( microtime( true ) - $this->lastPing ) < self::$PING_TTL ) {
4204                         if ( !func_num_args() || $this->lastRoundTripEstimate > 0 ) {
4205                                 $rtt = $this->lastRoundTripEstimate;
4206                                 return true; // don't care about $rtt
4207                         }
4208                 }
4209
4210                 // This will reconnect if possible or return false if not
4211                 $this->clearFlag( self::DBO_TRX, self::REMEMBER_PRIOR );
4212                 $ok = ( $this->query( self::$PING_QUERY, __METHOD__, true ) !== false );
4213                 $this->restoreFlags( self::RESTORE_PRIOR );
4214
4215                 if ( $ok ) {
4216                         $rtt = $this->lastRoundTripEstimate;
4217                 }
4218
4219                 return $ok;
4220         }
4221
4222         /**
4223          * Close any existing (dead) database connection and open a new connection
4224          *
4225          * @param string $fname
4226          * @return bool True if new connection is opened successfully, false if error
4227          */
4228         protected function replaceLostConnection( $fname ) {
4229                 $this->closeConnection();
4230                 $this->conn = false;
4231
4232                 $this->handleSessionLossPreconnect();
4233
4234                 try {
4235                         $this->open(
4236                                 $this->server,
4237                                 $this->user,
4238                                 $this->password,
4239                                 $this->getDBname(),
4240                                 $this->dbSchema(),
4241                                 $this->tablePrefix()
4242                         );
4243                         $this->lastPing = microtime( true );
4244                         $ok = true;
4245
4246                         $this->connLogger->warning(
4247                                 $fname . ': lost connection to {dbserver}; reconnected',
4248                                 [
4249                                         'dbserver' => $this->getServer(),
4250                                         'trace' => ( new RuntimeException() )->getTraceAsString()
4251                                 ]
4252                         );
4253                 } catch ( DBConnectionError $e ) {
4254                         $ok = false;
4255
4256                         $this->connLogger->error(
4257                                 $fname . ': lost connection to {dbserver} permanently',
4258                                 [ 'dbserver' => $this->getServer() ]
4259                         );
4260                 }
4261
4262                 $this->handleSessionLossPostconnect();
4263
4264                 return $ok;
4265         }
4266
4267         public function getSessionLagStatus() {
4268                 return $this->getRecordedTransactionLagStatus() ?: $this->getApproximateLagStatus();
4269         }
4270
4271         /**
4272          * Get the replica DB lag when the current transaction started
4273          *
4274          * This is useful when transactions might use snapshot isolation
4275          * (e.g. REPEATABLE-READ in innodb), so the "real" lag of that data
4276          * is this lag plus transaction duration. If they don't, it is still
4277          * safe to be pessimistic. This returns null if there is no transaction.
4278          *
4279          * This returns null if the lag status for this transaction was not yet recorded.
4280          *
4281          * @return array|null ('lag': seconds or false on error, 'since': UNIX timestamp of BEGIN)
4282          * @since 1.27
4283          */
4284         final protected function getRecordedTransactionLagStatus() {
4285                 return ( $this->trxLevel && $this->trxReplicaLag !== null )
4286                         ? [ 'lag' => $this->trxReplicaLag, 'since' => $this->trxTimestamp() ]
4287                         : null;
4288         }
4289
4290         /**
4291          * Get a replica DB lag estimate for this server
4292          *
4293          * @return array ('lag': seconds or false on error, 'since': UNIX timestamp of estimate)
4294          * @since 1.27
4295          */
4296         protected function getApproximateLagStatus() {
4297                 return [
4298                         'lag'   => $this->getLBInfo( 'replica' ) ? $this->getLag() : 0,
4299                         'since' => microtime( true )
4300                 ];
4301         }
4302
4303         /**
4304          * Merge the result of getSessionLagStatus() for several DBs
4305          * using the most pessimistic values to estimate the lag of
4306          * any data derived from them in combination
4307          *
4308          * This is information is useful for caching modules
4309          *
4310          * @see WANObjectCache::set()
4311          * @see WANObjectCache::getWithSetCallback()
4312          *
4313          * @param IDatabase $db1
4314          * @param IDatabase|null $db2 [optional]
4315          * @return array Map of values:
4316          *   - lag: highest lag of any of the DBs or false on error (e.g. replication stopped)
4317          *   - since: oldest UNIX timestamp of any of the DB lag estimates
4318          *   - pending: whether any of the DBs have uncommitted changes
4319          * @throws DBError
4320          * @since 1.27
4321          */
4322         public static function getCacheSetOptions( IDatabase $db1, IDatabase $db2 = null ) {
4323                 $res = [ 'lag' => 0, 'since' => INF, 'pending' => false ];
4324                 foreach ( func_get_args() as $db ) {
4325                         /** @var IDatabase $db */
4326                         $status = $db->getSessionLagStatus();
4327                         if ( $status['lag'] === false ) {
4328                                 $res['lag'] = false;
4329                         } elseif ( $res['lag'] !== false ) {
4330                                 $res['lag'] = max( $res['lag'], $status['lag'] );
4331                         }
4332                         $res['since'] = min( $res['since'], $status['since'] );
4333                         $res['pending'] = $res['pending'] ?: $db->writesPending();
4334                 }
4335
4336                 return $res;
4337         }
4338
4339         public function getLag() {
4340                 if ( $this->getLBInfo( 'master' ) ) {
4341                         return 0; // this is the master
4342                 } elseif ( $this->getLBInfo( 'is static' ) ) {
4343                         return 0; // static dataset
4344                 }
4345
4346                 return $this->doGetLag();
4347         }
4348
4349         protected function doGetLag() {
4350                 return 0;
4351         }
4352
4353         public function maxListLen() {
4354                 return 0;
4355         }
4356
4357         public function encodeBlob( $b ) {
4358                 return $b;
4359         }
4360
4361         public function decodeBlob( $b ) {
4362                 if ( $b instanceof Blob ) {
4363                         $b = $b->fetch();
4364                 }
4365                 return $b;
4366         }
4367
4368         public function setSessionOptions( array $options ) {
4369         }
4370
4371         public function sourceFile(
4372                 $filename,
4373                 callable $lineCallback = null,
4374                 callable $resultCallback = null,
4375                 $fname = false,
4376                 callable $inputCallback = null
4377         ) {
4378                 Wikimedia\suppressWarnings();
4379                 $fp = fopen( $filename, 'r' );
4380                 Wikimedia\restoreWarnings();
4381
4382                 if ( $fp === false ) {
4383                         throw new RuntimeException( "Could not open \"{$filename}\".\n" );
4384                 }
4385
4386                 if ( !$fname ) {
4387                         $fname = __METHOD__ . "( $filename )";
4388                 }
4389
4390                 try {
4391                         $error = $this->sourceStream(
4392                                 $fp, $lineCallback, $resultCallback, $fname, $inputCallback );
4393                 } catch ( Exception $e ) {
4394                         fclose( $fp );
4395                         throw $e;
4396                 }
4397
4398                 fclose( $fp );
4399
4400                 return $error;
4401         }
4402
4403         public function setSchemaVars( $vars ) {
4404                 $this->schemaVars = $vars;
4405         }
4406
4407         public function sourceStream(
4408                 $fp,
4409                 callable $lineCallback = null,
4410                 callable $resultCallback = null,
4411                 $fname = __METHOD__,
4412                 callable $inputCallback = null
4413         ) {
4414                 $delimiterReset = new ScopedCallback(
4415                         function ( $delimiter ) {
4416                                 $this->delimiter = $delimiter;
4417                         },
4418                         [ $this->delimiter ]
4419                 );
4420                 $cmd = '';
4421
4422                 while ( !feof( $fp ) ) {
4423                         if ( $lineCallback ) {
4424                                 call_user_func( $lineCallback );
4425                         }
4426
4427                         $line = trim( fgets( $fp ) );
4428
4429                         if ( $line == '' ) {
4430                                 continue;
4431                         }
4432
4433                         if ( $line[0] == '-' && $line[1] == '-' ) {
4434                                 continue;
4435                         }
4436
4437                         if ( $cmd != '' ) {
4438                                 $cmd .= ' ';
4439                         }
4440
4441                         $done = $this->streamStatementEnd( $cmd, $line );
4442
4443                         $cmd .= "$line\n";
4444
4445                         if ( $done || feof( $fp ) ) {
4446                                 $cmd = $this->replaceVars( $cmd );
4447
4448                                 if ( $inputCallback ) {
4449                                         $callbackResult = $inputCallback( $cmd );
4450
4451                                         if ( is_string( $callbackResult ) || !$callbackResult ) {
4452                                                 $cmd = $callbackResult;
4453                                         }
4454                                 }
4455
4456                                 if ( $cmd ) {
4457                                         $res = $this->query( $cmd, $fname );
4458
4459                                         if ( $resultCallback ) {
4460                                                 $resultCallback( $res, $this );
4461                                         }
4462
4463                                         if ( $res === false ) {
4464                                                 $err = $this->lastError();
4465
4466                                                 return "Query \"{$cmd}\" failed with error code \"$err\".\n";
4467                                         }
4468                                 }
4469                                 $cmd = '';
4470                         }
4471                 }
4472
4473                 ScopedCallback::consume( $delimiterReset );
4474                 return true;
4475         }
4476
4477         /**
4478          * Called by sourceStream() to check if we've reached a statement end
4479          *
4480          * @param string &$sql SQL assembled so far
4481          * @param string &$newLine New line about to be added to $sql
4482          * @return bool Whether $newLine contains end of the statement
4483          */
4484         public function streamStatementEnd( &$sql, &$newLine ) {
4485                 if ( $this->delimiter ) {
4486                         $prev = $newLine;
4487                         $newLine = preg_replace(
4488                                 '/' . preg_quote( $this->delimiter, '/' ) . '$/', '', $newLine );
4489                         if ( $newLine != $prev ) {
4490                                 return true;
4491                         }
4492                 }
4493
4494                 return false;
4495         }
4496
4497         /**
4498          * Database independent variable replacement. Replaces a set of variables
4499          * in an SQL statement with their contents as given by $this->getSchemaVars().
4500          *
4501          * Supports '{$var}' `{$var}` and / *$var* / (without the spaces) style variables.
4502          *
4503          * - '{$var}' should be used for text and is passed through the database's
4504          *   addQuotes method.
4505          * - `{$var}` should be used for identifiers (e.g. table and database names).
4506          *   It is passed through the database's addIdentifierQuotes method which
4507          *   can be overridden if the database uses something other than backticks.
4508          * - / *_* / or / *$wgDBprefix* / passes the name that follows through the
4509          *   database's tableName method.
4510          * - / *i* / passes the name that follows through the database's indexName method.
4511          * - In all other cases, / *$var* / is left unencoded. Except for table options,
4512          *   its use should be avoided. In 1.24 and older, string encoding was applied.
4513          *
4514          * @param string $ins SQL statement to replace variables in
4515          * @return string The new SQL statement with variables replaced
4516          */
4517         protected function replaceVars( $ins ) {
4518                 $vars = $this->getSchemaVars();
4519                 return preg_replace_callback(
4520                         '!
4521                                 /\* (\$wgDBprefix|[_i]) \*/ (\w*) | # 1-2. tableName, indexName
4522                                 \'\{\$ (\w+) }\'                  | # 3. addQuotes
4523                                 `\{\$ (\w+) }`                    | # 4. addIdentifierQuotes
4524                                 /\*\$ (\w+) \*/                     # 5. leave unencoded
4525                         !x',
4526                         function ( $m ) use ( $vars ) {
4527                                 // Note: Because of <https://bugs.php.net/bug.php?id=51881>,
4528                                 // check for both nonexistent keys *and* the empty string.
4529                                 if ( isset( $m[1] ) && $m[1] !== '' ) {
4530                                         if ( $m[1] === 'i' ) {
4531                                                 return $this->indexName( $m[2] );
4532                                         } else {
4533                                                 return $this->tableName( $m[2] );
4534                                         }
4535                                 } elseif ( isset( $m[3] ) && $m[3] !== '' && array_key_exists( $m[3], $vars ) ) {
4536                                         return $this->addQuotes( $vars[$m[3]] );
4537                                 } elseif ( isset( $m[4] ) && $m[4] !== '' && array_key_exists( $m[4], $vars ) ) {
4538                                         return $this->addIdentifierQuotes( $vars[$m[4]] );
4539                                 } elseif ( isset( $m[5] ) && $m[5] !== '' && array_key_exists( $m[5], $vars ) ) {
4540                                         return $vars[$m[5]];
4541                                 } else {
4542                                         return $m[0];
4543                                 }
4544                         },
4545                         $ins
4546                 );
4547         }
4548
4549         /**
4550          * Get schema variables. If none have been set via setSchemaVars(), then
4551          * use some defaults from the current object.
4552          *
4553          * @return array
4554          */
4555         protected function getSchemaVars() {
4556                 if ( $this->schemaVars ) {
4557                         return $this->schemaVars;
4558                 } else {
4559                         return $this->getDefaultSchemaVars();
4560                 }
4561         }
4562
4563         /**
4564          * Get schema variables to use if none have been set via setSchemaVars().
4565          *
4566          * Override this in derived classes to provide variables for tables.sql
4567          * and SQL patch files.
4568          *
4569          * @return array
4570          */
4571         protected function getDefaultSchemaVars() {
4572                 return [];
4573         }
4574
4575         public function lockIsFree( $lockName, $method ) {
4576                 // RDBMs methods for checking named locks may or may not count this thread itself.
4577                 // In MySQL, IS_FREE_LOCK() returns 0 if the thread already has the lock. This is
4578                 // the behavior choosen by the interface for this method.
4579                 return !isset( $this->sessionNamedLocks[$lockName] );
4580         }
4581
4582         public function lock( $lockName, $method, $timeout = 5 ) {
4583                 $this->sessionNamedLocks[$lockName] = 1;
4584
4585                 return true;
4586         }
4587
4588         public function unlock( $lockName, $method ) {
4589                 unset( $this->sessionNamedLocks[$lockName] );
4590
4591                 return true;
4592         }
4593
4594         public function getScopedLockAndFlush( $lockKey, $fname, $timeout ) {
4595                 if ( $this->writesOrCallbacksPending() ) {
4596                         // This only flushes transactions to clear snapshots, not to write data
4597                         $fnames = implode( ', ', $this->pendingWriteAndCallbackCallers() );
4598                         throw new DBUnexpectedError(
4599                                 $this,
4600                                 "$fname: Cannot flush pre-lock snapshot because writes are pending ($fnames)."
4601                         );
4602                 }
4603
4604                 if ( !$this->lock( $lockKey, $fname, $timeout ) ) {
4605                         return null;
4606                 }
4607
4608                 $unlocker = new ScopedCallback( function () use ( $lockKey, $fname ) {
4609                         if ( $this->trxLevel() ) {
4610                                 // There is a good chance an exception was thrown, causing any early return
4611                                 // from the caller. Let any error handler get a chance to issue rollback().
4612                                 // If there isn't one, let the error bubble up and trigger server-side rollback.
4613                                 $this->onTransactionResolution(
4614                                         function () use ( $lockKey, $fname ) {
4615                                                 $this->unlock( $lockKey, $fname );
4616                                         },
4617                                         $fname
4618                                 );
4619                         } else {
4620                                 $this->unlock( $lockKey, $fname );
4621                         }
4622                 } );
4623
4624                 $this->commit( $fname, self::FLUSHING_INTERNAL );
4625
4626                 return $unlocker;
4627         }
4628
4629         public function namedLocksEnqueue() {
4630                 return false;
4631         }
4632
4633         public function tableLocksHaveTransactionScope() {
4634                 return true;
4635         }
4636
4637         final public function lockTables( array $read, array $write, $method ) {
4638                 if ( $this->writesOrCallbacksPending() ) {
4639                         throw new DBUnexpectedError( $this, "Transaction writes or callbacks still pending." );
4640                 }
4641
4642                 if ( $this->tableLocksHaveTransactionScope() ) {
4643                         $this->startAtomic( $method );
4644                 }
4645
4646                 return $this->doLockTables( $read, $write, $method );
4647         }
4648
4649         /**
4650          * Helper function for lockTables() that handles the actual table locking
4651          *
4652          * @param array $read Array of tables to lock for read access
4653          * @param array $write Array of tables to lock for write access
4654          * @param string $method Name of caller
4655          * @return true
4656          */
4657         protected function doLockTables( array $read, array $write, $method ) {
4658                 return true;
4659         }
4660
4661         final public function unlockTables( $method ) {
4662                 if ( $this->tableLocksHaveTransactionScope() ) {
4663                         $this->endAtomic( $method );
4664
4665                         return true; // locks released on COMMIT/ROLLBACK
4666                 }
4667
4668                 return $this->doUnlockTables( $method );
4669         }
4670
4671         /**
4672          * Helper function for unlockTables() that handles the actual table unlocking
4673          *
4674          * @param string $method Name of caller
4675          * @return true
4676          */
4677         protected function doUnlockTables( $method ) {
4678                 return true;
4679         }
4680
4681         /**
4682          * Delete a table
4683          * @param string $tableName
4684          * @param string $fName
4685          * @return bool|IResultWrapper
4686          * @since 1.18
4687          */
4688         public function dropTable( $tableName, $fName = __METHOD__ ) {
4689                 if ( !$this->tableExists( $tableName, $fName ) ) {
4690                         return false;
4691                 }
4692                 $sql = "DROP TABLE " . $this->tableName( $tableName ) . " CASCADE";
4693
4694                 return $this->query( $sql, $fName );
4695         }
4696
4697         public function getInfinity() {
4698                 return 'infinity';
4699         }
4700
4701         public function encodeExpiry( $expiry ) {
4702                 return ( $expiry == '' || $expiry == 'infinity' || $expiry == $this->getInfinity() )
4703                         ? $this->getInfinity()
4704                         : $this->timestamp( $expiry );
4705         }
4706
4707         public function decodeExpiry( $expiry, $format = TS_MW ) {
4708                 if ( $expiry == '' || $expiry == 'infinity' || $expiry == $this->getInfinity() ) {
4709                         return 'infinity';
4710                 }
4711
4712                 return ConvertibleTimestamp::convert( $format, $expiry );
4713         }
4714
4715         public function setBigSelects( $value = true ) {
4716                 // no-op
4717         }
4718
4719         public function isReadOnly() {
4720                 return ( $this->getReadOnlyReason() !== false );
4721         }
4722
4723         /**
4724          * @return string|bool Reason this DB is read-only or false if it is not
4725          */
4726         protected function getReadOnlyReason() {
4727                 $reason = $this->getLBInfo( 'readOnlyReason' );
4728
4729                 return is_string( $reason ) ? $reason : false;
4730         }
4731
4732         public function setTableAliases( array $aliases ) {
4733                 $this->tableAliases = $aliases;
4734         }
4735
4736         public function setIndexAliases( array $aliases ) {
4737                 $this->indexAliases = $aliases;
4738         }
4739
4740         /**
4741          * @param int $field
4742          * @param int $flags
4743          * @return bool
4744          */
4745         protected function hasFlags( $field, $flags ) {
4746                 return ( ( $field & $flags ) === $flags );
4747         }
4748
4749         /**
4750          * Get the underlying binding connection handle
4751          *
4752          * Makes sure the connection resource is set (disconnects and ping() failure can unset it).
4753          * This catches broken callers than catch and ignore disconnection exceptions.
4754          * Unlike checking isOpen(), this is safe to call inside of open().
4755          *
4756          * @return mixed
4757          * @throws DBUnexpectedError
4758          * @since 1.26
4759          */
4760         protected function getBindingHandle() {
4761                 if ( !$this->conn ) {
4762                         throw new DBUnexpectedError(
4763                                 $this,
4764                                 'DB connection was already closed or the connection dropped.'
4765                         );
4766                 }
4767
4768                 return $this->conn;
4769         }
4770
4771         public function __toString() {
4772                 // spl_object_id is PHP >= 7.2
4773                 $id = function_exists( 'spl_object_id' )
4774                         ? spl_object_id( $this )
4775                         : spl_object_hash( $this );
4776
4777                 $description = $this->getType() . ' object #' . $id;
4778                 if ( is_resource( $this->conn ) ) {
4779                         $description .= ' (' . (string)$this->conn . ')'; // "resource id #<ID>"
4780                 } elseif ( is_object( $this->conn ) ) {
4781                         // spl_object_id is PHP >= 7.2
4782                         $handleId = function_exists( 'spl_object_id' )
4783                                 ? spl_object_id( $this->conn )
4784                                 : spl_object_hash( $this->conn );
4785                         $description .= " (handle id #$handleId)";
4786                 }
4787
4788                 return $description;
4789         }
4790
4791         /**
4792          * Make sure that copies do not share the same client binding handle
4793          * @throws DBConnectionError
4794          */
4795         public function __clone() {
4796                 $this->connLogger->warning(
4797                         "Cloning " . static::class . " is not recommended; forking connection:\n" .
4798                         ( new RuntimeException() )->getTraceAsString()
4799                 );
4800
4801                 if ( $this->isOpen() ) {
4802                         // Open a new connection resource without messing with the old one
4803                         $this->conn = false;
4804                         $this->trxEndCallbacks = []; // don't copy
4805                         $this->trxSectionCancelCallbacks = []; // don't copy
4806                         $this->handleSessionLossPreconnect(); // no trx or locks anymore
4807                         $this->open(
4808                                 $this->server,
4809                                 $this->user,
4810                                 $this->password,
4811                                 $this->getDBname(),
4812                                 $this->dbSchema(),
4813                                 $this->tablePrefix()
4814                         );
4815                         $this->lastPing = microtime( true );
4816                 }
4817         }
4818
4819         /**
4820          * Called by serialize. Throw an exception when DB connection is serialized.
4821          * This causes problems on some database engines because the connection is
4822          * not restored on unserialize.
4823          */
4824         public function __sleep() {
4825                 throw new RuntimeException( 'Database serialization may cause problems, since ' .
4826                         'the connection is not restored on wakeup.' );
4827         }
4828
4829         /**
4830          * Run a few simple sanity checks and close dangling connections
4831          */
4832         public function __destruct() {
4833                 if ( $this->trxLevel && $this->trxDoneWrites ) {
4834                         trigger_error( "Uncommitted DB writes (transaction from {$this->trxFname})." );
4835                 }
4836
4837                 $danglingWriters = $this->pendingWriteAndCallbackCallers();
4838                 if ( $danglingWriters ) {
4839                         $fnames = implode( ', ', $danglingWriters );
4840                         trigger_error( "DB transaction writes or callbacks still pending ($fnames)." );
4841                 }
4842
4843                 if ( $this->conn ) {
4844                         // Avoid connection leaks for sanity. Normally, resources close at script completion.
4845                         // The connection might already be closed in zend/hhvm by now, so suppress warnings.
4846                         Wikimedia\suppressWarnings();
4847                         $this->closeConnection();
4848                         Wikimedia\restoreWarnings();
4849                         $this->conn = false;
4850                 }
4851         }
4852 }
4853
4854 /**
4855  * @deprecated since 1.28
4856  */
4857 class_alias( Database::class, 'DatabaseBase' );
4858
4859 /**
4860  * @deprecated since 1.29
4861  */
4862 class_alias( Database::class, 'Database' );