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