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