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         /** Number of times to re-try an operation in case of deadlock */
  50         const DEADLOCK_TRIES = 4;
  51         /** Minimum time to wait before retry, in microseconds */
  52         const DEADLOCK_DELAY_MIN = 500000;
  53         /** Maximum time to wait before retry */
  54         const DEADLOCK_DELAY_MAX = 1500000;
  55
  56         /** How long before it is worth doing a dummy query to test the connection */
  57         const PING_TTL = 1.0;
  58         const PING_QUERY = 'SELECT 1 AS ping';
  59
  60         const TINY_WRITE_SEC = 0.010;
  61         const SLOW_WRITE_SEC = 0.500;
  62         const SMALL_WRITE_ROWS = 100;
  63
  64         /** @var string Whether lock granularity is on the level of the entire database */
  65         const ATTR_DB_LEVEL_LOCKING = 'db-level-locking';
  66
  67         /** @var int New Database instance will not be connected yet when returned */
  68         const NEW_UNCONNECTED = 0;
  69         /** @var int New Database instance will already be connected when returned */
  70         const NEW_CONNECTED = 1;
  71
  72         /** @var string SQL query */
  73         protected $lastQuery = '';
  74         /** @var float|bool UNIX timestamp of last write query */
  75         protected $lastWriteTime = false;
  76         /** @var string|bool */
  77         protected $phpError = false;
  78         /** @var string Server that this instance is currently connected to */
  79         protected $server;
  80         /** @var string User that this instance is currently connected under the name of */
  81         protected $user;
  82         /** @var string Password used to establish the current connection */
  83         protected $password;
  84         /** @var array[] Map of (table => (dbname, schema, prefix) map) */
  85         protected $tableAliases = [];
  86         /** @var string[] Map of (index alias => index) */
  87         protected $indexAliases = [];
  88         /** @var bool Whether this PHP instance is for a CLI script */
  89         protected $cliMode;
  90         /** @var string Agent name for query profiling */
  91         protected $agent;
  92         /** @var array Parameters used by initConnection() to establish a connection */
  93         protected $connectionParams = [];
  94         /** @var BagOStuff APC cache */
  95         protected $srvCache;
  96         /** @var LoggerInterface */
  97         protected $connLogger;
  98         /** @var LoggerInterface */
  99         protected $queryLogger;
 100         /** @var callback Error logging callback */
 101         protected $errorLogger;
 102         /** @var callback Deprecation logging callback */
 103         protected $deprecationLogger;
 104
 105         /** @var resource|null Database connection */
 106         protected $conn = null;
 107         /** @var bool */
 108         protected $opened = false;
 109
 110         /** @var array[] List of (callable, method name, atomic section id) */
 111         protected $trxIdleCallbacks = [];
 112         /** @var array[] List of (callable, method name, atomic section id) */
 113         protected $trxPreCommitCallbacks = [];
 114         /** @var array[] List of (callable, method name, atomic section id) */
 115         protected $trxEndCallbacks = [];
 116         /** @var callable[] Map of (name => callable) */
 117         protected $trxRecurringCallbacks = [];
 118         /** @var bool Whether to suppress triggering of transaction end callbacks */
 119         protected $trxEndCallbacksSuppressed = false;
 120
 121         /** @var int */
 122         protected $flags;
 123         /** @var array */
 124         protected $lbInfo = [];
 125         /** @var array|bool */
 126         protected $schemaVars = false;
 127         /** @var array */
 128         protected $sessionVars = [];
 129         /** @var array|null */
 130         protected $preparedArgs;
 131         /** @var string|bool|null Stashed value of html_errors INI setting */
 132         protected $htmlErrors;
 133         /** @var string */
 134         protected $delimiter = ';';
 135         /** @var DatabaseDomain */
 136         protected $currentDomain;
 137         /** @var integer|null Rows affected by the last query to query() or its CRUD wrappers */
 138         protected $affectedRowCount;
 139
 140         /**
 141          * @var int Transaction status
 142          */
 143         protected $trxStatus = self::STATUS_TRX_NONE;
 144         /**
 145          * @var Exception|null The last error that caused the status to become STATUS_TRX_ERROR
 146          */
 147         protected $trxStatusCause;
 148         /**
 149          * @var array|null If wasKnownStatementRollbackError() prevented trxStatus from being set,
 150          *  the relevant details are stored here.
 151          */
 152         protected $trxStatusIgnoredCause;
 153         /**
 154          * Either 1 if a transaction is active or 0 otherwise.
 155          * The other Trx fields may not be meaningfull if this is 0.
 156          *
 157          * @var int
 158          */
 159         protected $trxLevel = 0;
 160         /**
 161          * Either a short hexidecimal string if a transaction is active or ""
 162          *
 163          * @var string
 164          * @see Database::trxLevel
 165          */
 166         protected $trxShortId = '';
 167         /**
 168          * The UNIX time that the transaction started. Callers can assume that if
 169          * snapshot isolation is used, then the data is *at least* up to date to that
 170          * point (possibly more up-to-date since the first SELECT defines the snapshot).
 171          *
 172          * @var float|null
 173          * @see Database::trxLevel
 174          */
 175         private $trxTimestamp = null;
 176         /** @var float Lag estimate at the time of BEGIN */
 177         private $trxReplicaLag = null;
 178         /**
 179          * Remembers the function name given for starting the most recent transaction via begin().
 180          * Used to provide additional context for error reporting.
 181          *
 182          * @var string
 183          * @see Database::trxLevel
 184          */
 185         private $trxFname = null;
 186         /**
 187          * Record if possible write queries were done in the last transaction started
 188          *
 189          * @var bool
 190          * @see Database::trxLevel
 191          */
 192         private $trxDoneWrites = false;
 193         /**
 194          * Record if the current transaction was started implicitly due to DBO_TRX being set.
 195          *
 196          * @var bool
 197          * @see Database::trxLevel
 198          */
 199         private $trxAutomatic = false;
 200         /**
 201          * Counter for atomic savepoint identifiers. Reset when a new transaction begins.
 202          *
 203          * @var int
 204          */
 205         private $trxAtomicCounter = 0;
 206         /**
 207          * Array of levels of atomicity within transactions
 208          *
 209          * @var array List of (name, unique ID, savepoint ID)
 210          */
 211         private $trxAtomicLevels = [];
 212         /**
 213          * Record if the current transaction was started implicitly by Database::startAtomic
 214          *
 215          * @var bool
 216          */
 217         private $trxAutomaticAtomic = false;
 218         /**
 219          * Track the write query callers of the current transaction
 220          *
 221          * @var string[]
 222          */
 223         private $trxWriteCallers = [];
 224         /**
 225          * @var float Seconds spent in write queries for the current transaction
 226          */
 227         private $trxWriteDuration = 0.0;
 228         /**
 229          * @var int Number of write queries for the current transaction
 230          */
 231         private $trxWriteQueryCount = 0;
 232         /**
 233          * @var int Number of rows affected by write queries for the current transaction
 234          */
 235         private $trxWriteAffectedRows = 0;
 236         /**
 237          * @var float Like trxWriteQueryCount but excludes lock-bound, easy to replicate, queries
 238          */
 239         private $trxWriteAdjDuration = 0.0;
 240         /**
 241          * @var int Number of write queries counted in trxWriteAdjDuration
 242          */
 243         private $trxWriteAdjQueryCount = 0;
 244         /**
 245          * @var float RTT time estimate
 246          */
 247         private $rttEstimate = 0.0;
 248
 249         /** @var array Map of (name => 1) for locks obtained via lock() */
 250         private $namedLocksHeld = [];
 251         /** @var array Map of (table name => 1) for TEMPORARY tables */
 252         protected $sessionTempTables = [];
 253
 254         /** @var IDatabase|null Lazy handle to the master DB this server replicates from */
 255         private $lazyMasterHandle;
 256
 257         /** @var float UNIX timestamp */
 258         protected $lastPing = 0.0;
 259
 260         /** @var int[] Prior flags member variable values */
 261         private $priorFlags = [];
 262
 263         /** @var mixed Class name or object With profileIn/profileOut methods */
 264         protected $profiler;
 265         /** @var TransactionProfiler */
 266         protected $trxProfiler;
 267
 268         /** @var int */
 269         protected $nonNativeInsertSelectBatchSize = 10000;
 270
 271         /** @var string Idiom used when a cancelable atomic section started the transaction */
 272         private static $NOT_APPLICABLE = 'n/a';
 273         /** @var string Prefix to the atomic section counter used to make savepoint IDs */
 274         private static $SAVEPOINT_PREFIX = 'wikimedia_rdbms_atomic';
 275
 276         /** @var int Transaction is in a error state requiring a full or savepoint rollback */
 277         const STATUS_TRX_ERROR = 1;
 278         /** @var int Transaction is active and in a normal state */
 279         const STATUS_TRX_OK = 2;
 280         /** @var int No transaction is active */
 281         const STATUS_TRX_NONE = 3;
 282
 283         /**
 284          * @note exceptions for missing libraries/drivers should be thrown in initConnection()
 285          * @param array $params Parameters passed from Database::factory()
 286          */
 287         protected function __construct( array $params ) {
 288                 foreach ( [ 'host', 'user', 'password', 'dbname', 'schema', 'tablePrefix' ] as $name ) {
 289                         $this->connectionParams[$name] = $params[$name];
 290                 }
 291
 292                 $this->cliMode = $params['cliMode'];
 293                 // Agent name is added to SQL queries in a comment, so make sure it can't break out
 294                 $this->agent = str_replace( '/', '-', $params['agent'] );
 295
 296                 $this->flags = $params['flags'];
 297                 if ( $this->flags & self::DBO_DEFAULT ) {
 298                         if ( $this->cliMode ) {
 299                                 $this->flags &= ~self::DBO_TRX;
 300                         } else {
 301                                 $this->flags |= self::DBO_TRX;
 302                         }
 303                 }
 304                 // Disregard deprecated DBO_IGNORE flag (T189999)
 305                 $this->flags &= ~self::DBO_IGNORE;
 306
 307                 $this->sessionVars = $params['variables'];
 308
 309                 $this->srvCache = $params['srvCache'] ?? new HashBagOStuff();
 310
 311                 $this->profiler = $params['profiler'];
 312                 $this->trxProfiler = $params['trxProfiler'];
 313                 $this->connLogger = $params['connLogger'];
 314                 $this->queryLogger = $params['queryLogger'];
 315                 $this->errorLogger = $params['errorLogger'];
 316                 $this->deprecationLogger = $params['deprecationLogger'];
 317
 318                 if ( isset( $params['nonNativeInsertSelectBatchSize'] ) ) {
 319                         $this->nonNativeInsertSelectBatchSize = $params['nonNativeInsertSelectBatchSize'];
 320                 }
 321
 322                 // Set initial dummy domain until open() sets the final DB/prefix
 323                 $this->currentDomain = new DatabaseDomain(
 324                         $params['dbname'] != '' ? $params['dbname'] : null,
 325                         $params['schema'] != '' ? $params['schema'] : null,
 326                         $params['tablePrefix']
 327                 );
 328         }
 329
 330         /**
 331          * Initialize the connection to the database over the wire (or to local files)
 332          *
 333          * @throws LogicException
 334          * @throws InvalidArgumentException
 335          * @throws DBConnectionError
 336          * @since 1.31
 337          */
 338         final public function initConnection() {
 339                 if ( $this->isOpen() ) {
 340                         throw new LogicException( __METHOD__ . ': already connected.' );
 341                 }
 342                 // Establish the connection
 343                 $this->doInitConnection();
 344         }
 345
 346         /**
 347          * Actually connect to the database over the wire (or to local files)
 348          *
 349          * @throws InvalidArgumentException
 350          * @throws DBConnectionError
 351          * @since 1.31
 352          */
 353         protected function doInitConnection() {
 354                 if ( strlen( $this->connectionParams['user'] ) ) {
 355                         $this->open(
 356                                 $this->connectionParams['host'],
 357                                 $this->connectionParams['user'],
 358                                 $this->connectionParams['password'],
 359                                 $this->connectionParams['dbname'],
 360                                 $this->connectionParams['schema'],
 361                                 $this->connectionParams['tablePrefix']
 362                         );
 363                 } else {
 364                         throw new InvalidArgumentException( "No database user provided." );
 365                 }
 366         }
 367
 368         /**
 369          * Open a new connection to the database (closing any existing one)
 370          *
 371          * @param string $server Database server host
 372          * @param string $user Database user name
 373          * @param string $password Database user password
 374          * @param string $dbName Database name
 375          * @param string|null $schema Database schema name
 376          * @param string $tablePrefix Table prefix
 377          * @return bool
 378          * @throws DBConnectionError
 379          */
 380         abstract protected function open( $server, $user, $password, $dbName, $schema, $tablePrefix );
 381
 382         /**
 383          * Construct a Database subclass instance given a database type and parameters
 384          *
 385          * This also connects to the database immediately upon object construction
 386          *
 387          * @param string $dbType A possible DB type (sqlite, mysql, postgres,...)
 388          * @param array $p Parameter map with keys:
 389          *   - host : The hostname of the DB server
 390          *   - user : The name of the database user the client operates under
 391          *   - password : The password for the database user
 392          *   - dbname : The name of the database to use where queries do not specify one.
 393          *      The database must exist or an error might be thrown. Setting this to the empty string
 394          *      will avoid any such errors and make the handle have no implicit database scope. This is
 395          *      useful for queries like SHOW STATUS, CREATE DATABASE, or DROP DATABASE. Note that a
 396          *      "database" in Postgres is rougly equivalent to an entire MySQL server. This the domain
 397          *      in which user names and such are defined, e.g. users are database-specific in Postgres.
 398          *   - schema : The database schema to use (if supported). A "schema" in Postgres is roughly
 399          *      equivalent to a "database" in MySQL. Note that MySQL and SQLite do not use schemas.
 400          *   - tablePrefix : Optional table prefix that is implicitly added on to all table names
 401          *      recognized in queries. This can be used in place of schemas for handle site farms.
 402          *   - flags : Optional bitfield of DBO_* constants that define connection, protocol,
 403          *      buffering, and transaction behavior. It is STRONGLY adviced to leave the DBO_DEFAULT
 404          *      flag in place UNLESS this this database simply acts as a key/value store.
 405          *   - driver: Optional name of a specific DB client driver. For MySQL, there is only the
 406          *      'mysqli' driver; the old one 'mysql' has been removed.
 407          *   - variables: Optional map of session variables to set after connecting. This can be
 408          *      used to adjust lock timeouts or encoding modes and the like.
 409          *   - connLogger: Optional PSR-3 logger interface instance.
 410          *   - queryLogger: Optional PSR-3 logger interface instance.
 411          *   - profiler: Optional class name or object with profileIn()/profileOut() methods.
 412          *      These will be called in query(), using a simplified version of the SQL that also
 413          *      includes the agent as a SQL comment.
 414          *   - trxProfiler: Optional TransactionProfiler instance.
 415          *   - errorLogger: Optional callback that takes an Exception and logs it.
 416          *   - deprecationLogger: Optional callback that takes a string and logs it.
 417          *   - cliMode: Whether to consider the execution context that of a CLI script.
 418          *   - agent: Optional name used to identify the end-user in query profiling/logging.
 419          *   - srvCache: Optional BagOStuff instance to an APC-style cache.
 420          *   - nonNativeInsertSelectBatchSize: Optional batch size for non-native INSERT SELECT emulation.
 421          * @param int $connect One of the class constants (NEW_CONNECTED, NEW_UNCONNECTED) [optional]
 422          * @return Database|null If the database driver or extension cannot be found
 423          * @throws InvalidArgumentException If the database driver or extension cannot be found
 424          * @since 1.18
 425          */
 426         final public static function factory( $dbType, $p = [], $connect = self::NEW_CONNECTED ) {
 427                 $class = self::getClass( $dbType, $p['driver'] ?? null );
 428
 429                 if ( class_exists( $class ) && is_subclass_of( $class, IDatabase::class ) ) {
 430                         // Resolve some defaults for b/c
 431                         $p['host'] = $p['host'] ?? false;
 432                         $p['user'] = $p['user'] ?? false;
 433                         $p['password'] = $p['password'] ?? false;
 434                         $p['dbname'] = $p['dbname'] ?? false;
 435                         $p['flags'] = $p['flags'] ?? 0;
 436                         $p['variables'] = $p['variables'] ?? [];
 437                         $p['tablePrefix'] = $p['tablePrefix'] ?? '';
 438                         $p['schema'] = $p['schema'] ?? null;
 439                         $p['cliMode'] = $p['cliMode'] ?? ( PHP_SAPI === 'cli' || PHP_SAPI === 'phpdbg' );
 440                         $p['agent'] = $p['agent'] ?? '';
 441                         if ( !isset( $p['connLogger'] ) ) {
 442                                 $p['connLogger'] = new NullLogger();
 443                         }
 444                         if ( !isset( $p['queryLogger'] ) ) {
 445                                 $p['queryLogger'] = new NullLogger();
 446                         }
 447                         $p['profiler'] = $p['profiler'] ?? null;
 448                         if ( !isset( $p['trxProfiler'] ) ) {
 449                                 $p['trxProfiler'] = new TransactionProfiler();
 450                         }
 451                         if ( !isset( $p['errorLogger'] ) ) {
 452                                 $p['errorLogger'] = function ( Exception $e ) {
 453                                         trigger_error( get_class( $e ) . ': ' . $e->getMessage(), E_USER_WARNING );
 454                                 };
 455                         }
 456                         if ( !isset( $p['deprecationLogger'] ) ) {
 457                                 $p['deprecationLogger'] = function ( $msg ) {
 458                                         trigger_error( $msg, E_USER_DEPRECATED );
 459                                 };
 460                         }
 461
 462                         /** @var Database $conn */
 463                         $conn = new $class( $p );
 464                         if ( $connect == self::NEW_CONNECTED ) {
 465                                 $conn->initConnection();
 466                         }
 467                 } else {
 468                         $conn = null;
 469                 }
 470
 471                 return $conn;
 472         }
 473
 474         /**
 475          * @param string $dbType A possible DB type (sqlite, mysql, postgres,...)
 476          * @param string|null $driver Optional name of a specific DB client driver
 477          * @return array Map of (Database::ATTRIBUTE_* constant => value) for all such constants
 478          * @throws InvalidArgumentException
 479          * @since 1.31
 480          */
 481         final public static function attributesFromType( $dbType, $driver = null ) {
 482                 static $defaults = [ self::ATTR_DB_LEVEL_LOCKING => false ];
 483
 484                 $class = self::getClass( $dbType, $driver );
 485
 486                 return call_user_func( [ $class, 'getAttributes' ] ) + $defaults;
 487         }
 488
 489         /**
 490          * @param string $dbType A possible DB type (sqlite, mysql, postgres,...)
 491          * @param string|null $driver Optional name of a specific DB client driver
 492          * @return string Database subclass name to use
 493          * @throws InvalidArgumentException
 494          */
 495         private static function getClass( $dbType, $driver = null ) {
 496                 // For database types with built-in support, the below maps type to IDatabase
 497                 // implementations. For types with multipe driver implementations (PHP extensions),
 498                 // an array can be used, keyed by extension name. In case of an array, the
 499                 // optional 'driver' parameter can be used to force a specific driver. Otherwise,
 500                 // we auto-detect the first available driver. For types without built-in support,
 501                 // an class named "Database<Type>" us used, eg. DatabaseFoo for type 'foo'.
 502                 static $builtinTypes = [
 503                         'mssql' => DatabaseMssql::class,
 504                         'mysql' => [ 'mysqli' => DatabaseMysqli::class ],
 505                         'sqlite' => DatabaseSqlite::class,
 506                         'postgres' => DatabasePostgres::class,
 507                 ];
 508
 509                 $dbType = strtolower( $dbType );
 510                 $class = false;
 511
 512                 if ( isset( $builtinTypes[$dbType] ) ) {
 513                         $possibleDrivers = $builtinTypes[$dbType];
 514                         if ( is_string( $possibleDrivers ) ) {
 515                                 $class = $possibleDrivers;
 516                         } else {
 517                                 if ( (string)$driver !== '' ) {
 518                                         if ( !isset( $possibleDrivers[$driver] ) ) {
 519                                                 throw new InvalidArgumentException( __METHOD__ .
 520                                                         " type '$dbType' does not support driver '{$driver}'" );
 521                                         } else {
 522                                                 $class = $possibleDrivers[$driver];
 523                                         }
 524                                 } else {
 525                                         foreach ( $possibleDrivers as $posDriver => $possibleClass ) {
 526                                                 if ( extension_loaded( $posDriver ) ) {
 527                                                         $class = $possibleClass;
 528                                                         break;
 529                                                 }
 530                                         }
 531                                 }
 532                         }
 533                 } else {
 534                         $class = 'Database' . ucfirst( $dbType );
 535                 }
 536
 537                 if ( $class === false ) {
 538                         throw new InvalidArgumentException( __METHOD__ .
 539                                 " no viable database extension found for type '$dbType'" );
 540                 }
 541
 542                 return $class;
 543         }
 544
 545         /**
 546          * @return array Map of (Database::ATTRIBUTE_* constant => value
 547          * @since 1.31
 548          */
 549         protected static function getAttributes() {
 550                 return [];
 551         }
 552
 553         /**
 554          * Set the PSR-3 logger interface to use for query logging. (The logger
 555          * interfaces for connection logging and error logging can be set with the
 556          * constructor.)
 557          *
 558          * @param LoggerInterface $logger
 559          */
 560         public function setLogger( LoggerInterface $logger ) {
 561                 $this->queryLogger = $logger;
 562         }
 563
 564         public function getServerInfo() {
 565                 return $this->getServerVersion();
 566         }
 567
 568         public function bufferResults( $buffer = null ) {
 569                 $res = !$this->getFlag( self::DBO_NOBUFFER );
 570                 if ( $buffer !== null ) {
 571                         $buffer
 572                                 ? $this->clearFlag( self::DBO_NOBUFFER )
 573                                 : $this->setFlag( self::DBO_NOBUFFER );
 574                 }
 575
 576                 return $res;
 577         }
 578
 579         public function trxLevel() {
 580                 return $this->trxLevel;
 581         }
 582
 583         public function trxTimestamp() {
 584                 return $this->trxLevel ? $this->trxTimestamp : null;
 585         }
 586
 587         /**
 588          * @return int One of the STATUS_TRX_* class constants
 589          * @since 1.31
 590          */
 591         public function trxStatus() {
 592                 return $this->trxStatus;
 593         }
 594
 595         public function tablePrefix( $prefix = null ) {
 596                 $old = $this->currentDomain->getTablePrefix();
 597                 if ( $prefix !== null ) {
 598                         $this->currentDomain = new DatabaseDomain(
 599                                 $this->currentDomain->getDatabase(),
 600                                 $this->currentDomain->getSchema(),
 601                                 $prefix
 602                         );
 603                 }
 604
 605                 return $old;
 606         }
 607
 608         public function dbSchema( $schema = null ) {
 609                 $old = $this->currentDomain->getSchema();
 610                 if ( $schema !== null ) {
 611                         $this->currentDomain = new DatabaseDomain(
 612                                 $this->currentDomain->getDatabase(),
 613                                 // DatabaseDomain uses null for unspecified schemas
 614                                 strlen( $schema ) ? $schema : null,
 615                                 $this->currentDomain->getTablePrefix()
 616                         );
 617                 }
 618
 619                 return (string)$old;
 620         }
 621
 622         /**
 623          * @return string Schema to use to qualify relations in queries
 624          */
 625         protected function relationSchemaQualifier() {
 626                 return $this->dbSchema();
 627         }
 628
 629         public function getLBInfo( $name = null ) {
 630                 if ( is_null( $name ) ) {
 631                         return $this->lbInfo;
 632                 } else {
 633                         if ( array_key_exists( $name, $this->lbInfo ) ) {
 634                                 return $this->lbInfo[$name];
 635                         } else {
 636                                 return null;
 637                         }
 638                 }
 639         }
 640
 641         public function setLBInfo( $name, $value = null ) {
 642                 if ( is_null( $value ) ) {
 643                         $this->lbInfo = $name;
 644                 } else {
 645                         $this->lbInfo[$name] = $value;
 646                 }
 647         }
 648
 649         public function setLazyMasterHandle( IDatabase $conn ) {
 650                 $this->lazyMasterHandle = $conn;
 651         }
 652
 653         /**
 654          * @return IDatabase|null
 655          * @see setLazyMasterHandle()
 656          * @since 1.27
 657          */
 658         protected function getLazyMasterHandle() {
 659                 return $this->lazyMasterHandle;
 660         }
 661
 662         public function implicitGroupby() {
 663                 return true;
 664         }
 665
 666         public function implicitOrderby() {
 667                 return true;
 668         }
 669
 670         public function lastQuery() {
 671                 return $this->lastQuery;
 672         }
 673
 674         public function doneWrites() {
 675                 return (bool)$this->lastWriteTime;
 676         }
 677
 678         public function lastDoneWrites() {
 679                 return $this->lastWriteTime ?: false;
 680         }
 681
 682         public function writesPending() {
 683                 return $this->trxLevel && $this->trxDoneWrites;
 684         }
 685
 686         public function writesOrCallbacksPending() {
 687                 return $this->trxLevel && (
 688                         $this->trxDoneWrites ||
 689                         $this->trxIdleCallbacks ||
 690                         $this->trxPreCommitCallbacks ||
 691                         $this->trxEndCallbacks
 692                 );
 693         }
 694
 695         public function preCommitCallbacksPending() {
 696                 return $this->trxLevel && $this->trxPreCommitCallbacks;
 697         }
 698
 699         /**
 700          * @return string|null
 701          */
 702         final protected function getTransactionRoundId() {
 703                 // If transaction round participation is enabled, see if one is active
 704                 if ( $this->getFlag( self::DBO_TRX ) ) {
 705                         $id = $this->getLBInfo( 'trxRoundId' );
 706
 707                         return is_string( $id ) ? $id : null;
 708                 }
 709
 710                 return null;
 711         }
 712
 713         public function pendingWriteQueryDuration( $type = self::ESTIMATE_TOTAL ) {
 714                 if ( !$this->trxLevel ) {
 715                         return false;
 716                 } elseif ( !$this->trxDoneWrites ) {
 717                         return 0.0;
 718                 }
 719
 720                 switch ( $type ) {
 721                         case self::ESTIMATE_DB_APPLY:
 722                                 $this->ping( $rtt );
 723                                 $rttAdjTotal = $this->trxWriteAdjQueryCount * $rtt;
 724                                 $applyTime = max( $this->trxWriteAdjDuration - $rttAdjTotal, 0 );
 725                                 // For omitted queries, make them count as something at least
 726                                 $omitted = $this->trxWriteQueryCount - $this->trxWriteAdjQueryCount;
 727                                 $applyTime += self::TINY_WRITE_SEC * $omitted;
 728
 729                                 return $applyTime;
 730                         default: // everything
 731                                 return $this->trxWriteDuration;
 732                 }
 733         }
 734
 735         public function pendingWriteCallers() {
 736                 return $this->trxLevel ? $this->trxWriteCallers : [];
 737         }
 738
 739         public function pendingWriteRowsAffected() {
 740                 return $this->trxWriteAffectedRows;
 741         }
 742
 743         /**
 744          * List the methods that have write queries or callbacks for the current transaction
 745          *
 746          * This method should not be used outside of Database/LoadBalancer
 747          *
 748          * @return string[]
 749          * @since 1.32
 750          */
 751         public function pendingWriteAndCallbackCallers() {
 752                 $fnames = $this->pendingWriteCallers();
 753                 foreach ( [
 754                         $this->trxIdleCallbacks,
 755                         $this->trxPreCommitCallbacks,
 756                         $this->trxEndCallbacks
 757                 ] as $callbacks ) {
 758                         foreach ( $callbacks as $callback ) {
 759                                 $fnames[] = $callback[1];
 760                         }
 761                 }
 762
 763                 return $fnames;
 764         }
 765
 766         /**
 767          * @return string
 768          */
 769         private function flatAtomicSectionList() {
 770                 return array_reduce( $this->trxAtomicLevels, function ( $accum, $v ) {
 771                         return $accum === null ? $v[0] : "$accum, " . $v[0];
 772                 } );
 773         }
 774
 775         public function isOpen() {
 776                 return $this->opened;
 777         }
 778
 779         public function setFlag( $flag, $remember = self::REMEMBER_NOTHING ) {
 780                 if ( ( $flag & self::DBO_IGNORE ) ) {
 781                         throw new UnexpectedValueException( "Modifying DBO_IGNORE is not allowed." );
 782                 }
 783
 784                 if ( $remember === self::REMEMBER_PRIOR ) {
 785                         array_push( $this->priorFlags, $this->flags );
 786                 }
 787                 $this->flags |= $flag;
 788         }
 789
 790         public function clearFlag( $flag, $remember = self::REMEMBER_NOTHING ) {
 791                 if ( ( $flag & self::DBO_IGNORE ) ) {
 792                         throw new UnexpectedValueException( "Modifying DBO_IGNORE is not allowed." );
 793                 }
 794
 795                 if ( $remember === self::REMEMBER_PRIOR ) {
 796                         array_push( $this->priorFlags, $this->flags );
 797                 }
 798                 $this->flags &= ~$flag;
 799         }
 800
 801         public function restoreFlags( $state = self::RESTORE_PRIOR ) {
 802                 if ( !$this->priorFlags ) {
 803                         return;
 804                 }
 805
 806                 if ( $state === self::RESTORE_INITIAL ) {
 807                         $this->flags = reset( $this->priorFlags );
 808                         $this->priorFlags = [];
 809                 } else {
 810                         $this->flags = array_pop( $this->priorFlags );
 811                 }
 812         }
 813
 814         public function getFlag( $flag ) {
 815                 return !!( $this->flags & $flag );
 816         }
 817
 818         /**
 819          * @param string $name Class field name
 820          * @return mixed
 821          * @deprecated Since 1.28
 822          */
 823         public function getProperty( $name ) {
 824                 return $this->$name;
 825         }
 826
 827         public function getDomainID() {
 828                 return $this->currentDomain->getId();
 829         }
 830
 831         final public function getWikiID() {
 832                 return $this->getDomainID();
 833         }
 834
 835         /**
 836          * Get information about an index into an object
 837          * @param string $table Table name
 838          * @param string $index Index name
 839          * @param string $fname Calling function name
 840          * @return mixed Database-specific index description class or false if the index does not exist
 841          */
 842         abstract function indexInfo( $table, $index, $fname = __METHOD__ );
 843
 844         /**
 845          * Wrapper for addslashes()
 846          *
 847          * @param string $s String to be slashed.
 848          * @return string Slashed string.
 849          */
 850         abstract function strencode( $s );
 851
 852         /**
 853          * Set a custom error handler for logging errors during database connection
 854          */
 855         protected function installErrorHandler() {
 856                 $this->phpError = false;
 857                 $this->htmlErrors = ini_set( 'html_errors', '0' );
 858                 set_error_handler( [ $this, 'connectionErrorLogger' ] );
 859         }
 860
 861         /**
 862          * Restore the previous error handler and return the last PHP error for this DB
 863          *
 864          * @return bool|string
 865          */
 866         protected function restoreErrorHandler() {
 867                 restore_error_handler();
 868                 if ( $this->htmlErrors !== false ) {
 869                         ini_set( 'html_errors', $this->htmlErrors );
 870                 }
 871
 872                 return $this->getLastPHPError();
 873         }
 874
 875         /**
 876          * @return string|bool Last PHP error for this DB (typically connection errors)
 877          */
 878         protected function getLastPHPError() {
 879                 if ( $this->phpError ) {
 880                         $error = preg_replace( '!\[<a.*</a>\]!', '', $this->phpError );
 881                         $error = preg_replace( '!^.*?:\s?(.*)$!', '$1', $error );
 882
 883                         return $error;
 884                 }
 885
 886                 return false;
 887         }
 888
 889         /**
 890          * Error handler for logging errors during database connection
 891          * This method should not be used outside of Database classes
 892          *
 893          * @param int $errno
 894          * @param string $errstr
 895          */
 896         public function connectionErrorLogger( $errno, $errstr ) {
 897                 $this->phpError = $errstr;
 898         }
 899
 900         /**
 901          * Create a log context to pass to PSR-3 logger functions.
 902          *
 903          * @param array $extras Additional data to add to context
 904          * @return array
 905          */
 906         protected function getLogContext( array $extras = [] ) {
 907                 return array_merge(
 908                         [
 909                                 'db_server' => $this->server,
 910                                 'db_name' => $this->getDBname(),
 911                                 'db_user' => $this->user,
 912                         ],
 913                         $extras
 914                 );
 915         }
 916
 917         final public function close() {
 918                 $exception = null; // error to throw after disconnecting
 919
 920                 if ( $this->conn ) {
 921                         // Roll back any dangling transaction first
 922                         if ( $this->trxLevel ) {
 923                                 if ( $this->trxAtomicLevels ) {
 924                                         // Cannot let incomplete atomic sections be committed
 925                                         $levels = $this->flatAtomicSectionList();
 926                                         $exception = new DBUnexpectedError(
 927                                                 $this,
 928                                                 __METHOD__ . ": atomic sections $levels are still open."
 929                                         );
 930                                 } elseif ( $this->trxAutomatic ) {
 931                                         // Only the connection manager can commit non-empty DBO_TRX transactions
 932                                         // (empty ones we can silently roll back)
 933                                         if ( $this->writesOrCallbacksPending() ) {
 934                                                 $exception = new DBUnexpectedError(
 935                                                         $this,
 936                                                         __METHOD__ .
 937                                                         ": mass commit/rollback of peer transaction required (DBO_TRX set)."
 938                                                 );
 939                                         }
 940                                 } else {
 941                                         // Manual transactions should have been committed or rolled
 942                                         // back, even if empty.
 943                                         $exception = new DBUnexpectedError(
 944                                                 $this,
 945                                                 __METHOD__ . ": transaction is still open (from {$this->trxFname})."
 946                                         );
 947                                 }
 948
 949                                 if ( $this->trxEndCallbacksSuppressed ) {
 950                                         $exception = $exception ?: new DBUnexpectedError(
 951                                                 $this,
 952                                                 __METHOD__ . ': callbacks are suppressed; cannot properly commit.'
 953                                         );
 954                                 }
 955
 956                                 // Rollback the changes and run any callbacks as needed
 957                                 $this->rollback( __METHOD__, self::FLUSHING_INTERNAL );
 958                         }
 959
 960                         // Close the actual connection in the binding handle
 961                         $closed = $this->closeConnection();
 962                         $this->conn = false;
 963                 } else {
 964                         $closed = true; // already closed; nothing to do
 965                 }
 966
 967                 $this->opened = false;
 968
 969                 // Throw any unexpected errors after having disconnected
 970                 if ( $exception instanceof Exception ) {
 971                         throw $exception;
 972                 }
 973
 974                 // Sanity check that no callbacks are dangling
 975                 $fnames = $this->pendingWriteAndCallbackCallers();
 976                 if ( $fnames ) {
 977                         throw new RuntimeException(
 978                                 "Transaction callbacks are still pending:\n" . implode( ', ', $fnames )
 979                         );
 980                 }
 981
 982                 return $closed;
 983         }
 984
 985         /**
 986          * Make sure isOpen() returns true as a sanity check
 987          *
 988          * @throws DBUnexpectedError
 989          */
 990         protected function assertOpen() {
 991                 if ( !$this->isOpen() ) {
 992                         throw new DBUnexpectedError( $this, "DB connection was already closed." );
 993                 }
 994         }
 995
 996         /**
 997          * Closes underlying database connection
 998          * @since 1.20
 999          * @return bool Whether connection was closed successfully
1000          */
1001         abstract protected function closeConnection();
1002
1003         /**
1004          * @deprecated since 1.32
1005          * @param string $error Fallback message, if none is given by DB
1006          * @throws DBConnectionError
1007          */
1008         public function reportConnectionError( $error = 'Unknown error' ) {
1009                 call_user_func( $this->deprecationLogger, 'Use of ' . __METHOD__ . ' is deprecated.' );
1010                 throw new DBConnectionError( $this, $this->lastError() ?: $error );
1011         }
1012
1013         /**
1014          * Run a query and return a DBMS-dependent wrapper (that has all IResultWrapper methods)
1015          *
1016          * This might return things, such as mysqli_result, that do not formally implement
1017          * IResultWrapper, but nonetheless implement all of its methods correctly
1018          *
1019          * @param string $sql SQL query.
1020          * @return IResultWrapper|bool Iterator to feed to fetchObject/fetchRow; false on failure
1021          */
1022         abstract protected function doQuery( $sql );
1023
1024         /**
1025          * Determine whether a query writes to the DB. When in doubt, this returns true.
1026          *
1027          * Main use cases:
1028          *
1029          * - Subsequent web requests should not need to wait for replication from
1030          *   the master position seen by this web request, unless this request made
1031          *   changes to the master. This is handled by ChronologyProtector by checking
1032          *   doneWrites() at the end of the request. doneWrites() returns true if any
1033          *   query set lastWriteTime; which query() does based on isWriteQuery().
1034          *
1035          * - Reject write queries to replica DBs, in query().
1036          *
1037          * @param string $sql
1038          * @return bool
1039          */
1040         protected function isWriteQuery( $sql ) {
1041                 // BEGIN and COMMIT queries are considered read queries here.
1042                 // Database backends and drivers (MySQL, MariaDB, php-mysqli) generally
1043                 // treat these as write queries, in that their results have "affected rows"
1044                 // as meta data as from writes, instead of "num rows" as from reads.
1045                 // But, we treat them as read queries because when reading data (from
1046                 // either replica or master) we use transactions to enable repeatable-read
1047                 // snapshots, which ensures we get consistent results from the same snapshot
1048                 // for all queries within a request. Use cases:
1049                 // - Treating these as writes would trigger ChronologyProtector (see method doc).
1050                 // - We use this method to reject writes to replicas, but we need to allow
1051                 //   use of transactions on replicas for read snapshots. This fine given
1052                 //   that transactions by themselves don't make changes, only actual writes
1053                 //   within the transaction matter, which we still detect.
1054                 return !preg_match(
1055                         '/^(?:SELECT|BEGIN|ROLLBACK|COMMIT|SET|SHOW|EXPLAIN|\(SELECT)\b/i', $sql );
1056         }
1057
1058         /**
1059          * @param string $sql
1060          * @return string|null
1061          */
1062         protected function getQueryVerb( $sql ) {
1063                 return preg_match( '/^\s*([a-z]+)/i', $sql, $m ) ? strtoupper( $m[1] ) : null;
1064         }
1065
1066         /**
1067          * Determine whether a SQL statement is sensitive to isolation level.
1068          *
1069          * A SQL statement is considered transactable if its result could vary
1070          * depending on the transaction isolation level. Operational commands
1071          * such as 'SET' and 'SHOW' are not considered to be transactable.
1072          *
1073          * Main purpose: Used by query() to decide whether to begin a transaction
1074          * before the current query (in DBO_TRX mode, on by default).
1075          *
1076          * @param string $sql
1077          * @return bool
1078          */
1079         protected function isTransactableQuery( $sql ) {
1080                 return !in_array(
1081                         $this->getQueryVerb( $sql ),
1082                         [ 'BEGIN', 'ROLLBACK', 'COMMIT', 'SET', 'SHOW', 'CREATE', 'ALTER' ],
1083                         true
1084                 );
1085         }
1086
1087         /**
1088          * @param string $sql A SQL query
1089          * @return bool Whether $sql is SQL for TEMPORARY table operation
1090          */
1091         protected function registerTempTableOperation( $sql ) {
1092                 if ( preg_match(
1093                         '/^CREATE\s+TEMPORARY\s+TABLE\s+(?:IF\s+NOT\s+EXISTS\s+)?[`"\']?(\w+)[`"\']?/i',
1094                         $sql,
1095                         $matches
1096                 ) ) {
1097                         $this->sessionTempTables[$matches[1]] = 1;
1098
1099                         return true;
1100                 } elseif ( preg_match(
1101                         '/^DROP\s+(?:TEMPORARY\s+)?TABLE\s+(?:IF\s+EXISTS\s+)?[`"\']?(\w+)[`"\']?/i',
1102                         $sql,
1103                         $matches
1104                 ) ) {
1105                         $isTemp = isset( $this->sessionTempTables[$matches[1]] );
1106                         unset( $this->sessionTempTables[$matches[1]] );
1107
1108                         return $isTemp;
1109                 } elseif ( preg_match(
1110                         '/^TRUNCATE\s+(?:TEMPORARY\s+)?TABLE\s+(?:IF\s+EXISTS\s+)?[`"\']?(\w+)[`"\']?/i',
1111                         $sql,
1112                         $matches
1113                 ) ) {
1114                         return isset( $this->sessionTempTables[$matches[1]] );
1115                 } elseif ( preg_match(
1116                         '/^(?:INSERT\s+(?:\w+\s+)?INTO|UPDATE|DELETE\s+FROM)\s+[`"\']?(\w+)[`"\']?/i',
1117                         $sql,
1118                         $matches
1119                 ) ) {
1120                         return isset( $this->sessionTempTables[$matches[1]] );
1121                 }
1122
1123                 return false;
1124         }
1125
1126         public function query( $sql, $fname = __METHOD__, $tempIgnore = false ) {
1127                 $this->assertTransactionStatus( $sql, $fname );
1128
1129                 # Avoid fatals if close() was called
1130                 $this->assertOpen();
1131
1132                 $priorWritesPending = $this->writesOrCallbacksPending();
1133                 $this->lastQuery = $sql;
1134
1135                 $isWrite = $this->isWriteQuery( $sql );
1136                 if ( $isWrite ) {
1137                         $isNonTempWrite = !$this->registerTempTableOperation( $sql );
1138                 } else {
1139                         $isNonTempWrite = false;
1140                 }
1141
1142                 if ( $isWrite ) {
1143                         if ( $this->getLBInfo( 'replica' ) === true ) {
1144                                 throw new DBError(
1145                                         $this,
1146                                         'Write operations are not allowed on replica database connections.'
1147                                 );
1148                         }
1149                         # In theory, non-persistent writes are allowed in read-only mode, but due to things
1150                         # like https://bugs.mysql.com/bug.php?id=33669 that might not work anyway...
1151                         $reason = $this->getReadOnlyReason();
1152                         if ( $reason !== false ) {
1153                                 throw new DBReadOnlyError( $this, "Database is read-only: $reason" );
1154                         }
1155                         # Set a flag indicating that writes have been done
1156                         $this->lastWriteTime = microtime( true );
1157                 }
1158
1159                 # Add trace comment to the begin of the sql string, right after the operator.
1160                 # Or, for one-word queries (like "BEGIN" or COMMIT") add it to the end (T44598)
1161                 $commentedSql = preg_replace( '/\s|$/', " /* $fname {$this->agent} */ ", $sql, 1 );
1162
1163                 # Start implicit transactions that wrap the request if DBO_TRX is enabled
1164                 if ( !$this->trxLevel && $this->getFlag( self::DBO_TRX )
1165                         && $this->isTransactableQuery( $sql )
1166                 ) {
1167                         $this->begin( __METHOD__ . " ($fname)", self::TRANSACTION_INTERNAL );
1168                         $this->trxAutomatic = true;
1169                 }
1170
1171                 # Keep track of whether the transaction has write queries pending
1172                 if ( $this->trxLevel && !$this->trxDoneWrites && $isWrite ) {
1173                         $this->trxDoneWrites = true;
1174                         $this->trxProfiler->transactionWritingIn(
1175                                 $this->server, $this->getDomainID(), $this->trxShortId );
1176                 }
1177
1178                 if ( $this->getFlag( self::DBO_DEBUG ) ) {
1179                         $this->queryLogger->debug( "{$this->getDomainID()} {$commentedSql}" );
1180                 }
1181
1182                 # Send the query to the server and fetch any corresponding errors
1183                 $ret = $this->doProfiledQuery( $sql, $commentedSql, $isNonTempWrite, $fname );
1184                 $lastError = $this->lastError();
1185                 $lastErrno = $this->lastErrno();
1186
1187                 # Try reconnecting if the connection was lost
1188                 if ( $ret === false && $this->wasConnectionLoss() ) {
1189                         # Check if any meaningful session state was lost
1190                         $recoverable = $this->canRecoverFromDisconnect( $sql, $priorWritesPending );
1191                         # Update session state tracking and try to restore the connection
1192                         $reconnected = $this->replaceLostConnection( __METHOD__ );
1193                         # Silently resend the query to the server if it is safe and possible
1194                         if ( $reconnected && $recoverable ) {
1195                                 $ret = $this->doProfiledQuery( $sql, $commentedSql, $isNonTempWrite, $fname );
1196                                 $lastError = $this->lastError();
1197                                 $lastErrno = $this->lastErrno();
1198
1199                                 if ( $ret === false && $this->wasConnectionLoss() ) {
1200                                         # Query probably causes disconnects; reconnect and do not re-run it
1201                                         $this->replaceLostConnection( __METHOD__ );
1202                                 }
1203                         }
1204                 }
1205
1206                 if ( $ret === false ) {
1207                         if ( $this->trxLevel ) {
1208                                 if ( $this->wasKnownStatementRollbackError() ) {
1209                                         # We're ignoring an error that caused just the current query to be aborted.
1210                                         # But log the cause so we can log a deprecation notice if a caller actually
1211                                         # does ignore it.
1212                                         $this->trxStatusIgnoredCause = [ $lastError, $lastErrno, $fname ];
1213                                 } else {
1214                                         # Either the query was aborted or all queries after BEGIN where aborted.
1215                                         # In the first case, the only options going forward are (a) ROLLBACK, or
1216                                         # (b) ROLLBACK TO SAVEPOINT (if one was set). If the later case, the only
1217                                         # option is ROLLBACK, since the snapshots would have been released.
1218                                         $this->trxStatus = self::STATUS_TRX_ERROR;
1219                                         $this->trxStatusCause =
1220                                                 $this->makeQueryException( $lastError, $lastErrno, $sql, $fname );
1221                                         $tempIgnore = false; // cannot recover
1222                                         $this->trxStatusIgnoredCause = null;
1223                                 }
1224                         }
1225
1226                         $this->reportQueryError( $lastError, $lastErrno, $sql, $fname, $tempIgnore );
1227                 }
1228
1229                 return $this->resultObject( $ret );
1230         }
1231
1232         /**
1233          * Wrapper for query() that also handles profiling, logging, and affected row count updates
1234          *
1235          * @param string $sql Original SQL query
1236          * @param string $commentedSql SQL query with debugging/trace comment
1237          * @param bool $isWrite Whether the query is a (non-temporary) write operation
1238          * @param string $fname Name of the calling function
1239          * @return bool|ResultWrapper True for a successful write query, ResultWrapper
1240          *     object for a successful read query, or false on failure
1241          */
1242         private function doProfiledQuery( $sql, $commentedSql, $isWrite, $fname ) {
1243                 $isMaster = !is_null( $this->getLBInfo( 'master' ) );
1244                 # generalizeSQL() will probably cut down the query to reasonable
1245                 # logging size most of the time. The substr is really just a sanity check.
1246                 if ( $isMaster ) {
1247                         $queryProf = 'query-m: ' . substr( self::generalizeSQL( $sql ), 0, 255 );
1248                 } else {
1249                         $queryProf = 'query: ' . substr( self::generalizeSQL( $sql ), 0, 255 );
1250                 }
1251
1252                 # Include query transaction state
1253                 $queryProf .= $this->trxShortId ? " [TRX#{$this->trxShortId}]" : "";
1254
1255                 $startTime = microtime( true );
1256                 if ( $this->profiler ) {
1257                         $this->profiler->profileIn( $queryProf );
1258                 }
1259                 $this->affectedRowCount = null;
1260                 $ret = $this->doQuery( $commentedSql );
1261                 $this->affectedRowCount = $this->affectedRows();
1262                 if ( $this->profiler ) {
1263                         $this->profiler->profileOut( $queryProf );
1264                 }
1265                 $queryRuntime = max( microtime( true ) - $startTime, 0.0 );
1266
1267                 unset( $queryProfSection ); // profile out (if set)
1268
1269                 if ( $ret !== false ) {
1270                         $this->lastPing = $startTime;
1271                         if ( $isWrite && $this->trxLevel ) {
1272                                 $this->updateTrxWriteQueryTime( $sql, $queryRuntime, $this->affectedRows() );
1273                                 $this->trxWriteCallers[] = $fname;
1274                         }
1275                 }
1276
1277                 if ( $sql === self::PING_QUERY ) {
1278                         $this->rttEstimate = $queryRuntime;
1279                 }
1280
1281                 $this->trxProfiler->recordQueryCompletion(
1282                         $queryProf,
1283                         $startTime,
1284                         $isWrite,
1285                         $isWrite ? $this->affectedRows() : $this->numRows( $ret )
1286                 );
1287                 $this->queryLogger->debug( $sql, [
1288                         'method' => $fname,
1289                         'master' => $isMaster,
1290                         'runtime' => $queryRuntime,
1291                 ] );
1292
1293                 return $ret;
1294         }
1295
1296         /**
1297          * Update the estimated run-time of a query, not counting large row lock times
1298          *
1299          * LoadBalancer can be set to rollback transactions that will create huge replication
1300          * lag. It bases this estimate off of pendingWriteQueryDuration(). Certain simple
1301          * queries, like inserting a row can take a long time due to row locking. This method
1302          * uses some simple heuristics to discount those cases.
1303          *
1304          * @param string $sql A SQL write query
1305          * @param float $runtime Total runtime, including RTT
1306          * @param int $affected Affected row count
1307          */
1308         private function updateTrxWriteQueryTime( $sql, $runtime, $affected ) {
1309                 // Whether this is indicative of replica DB runtime (except for RBR or ws_repl)
1310                 $indicativeOfReplicaRuntime = true;
1311                 if ( $runtime > self::SLOW_WRITE_SEC ) {
1312                         $verb = $this->getQueryVerb( $sql );
1313                         // insert(), upsert(), replace() are fast unless bulky in size or blocked on locks
1314                         if ( $verb === 'INSERT' ) {
1315                                 $indicativeOfReplicaRuntime = $this->affectedRows() > self::SMALL_WRITE_ROWS;
1316                         } elseif ( $verb === 'REPLACE' ) {
1317                                 $indicativeOfReplicaRuntime = $this->affectedRows() > self::SMALL_WRITE_ROWS / 2;
1318                         }
1319                 }
1320
1321                 $this->trxWriteDuration += $runtime;
1322                 $this->trxWriteQueryCount += 1;
1323                 $this->trxWriteAffectedRows += $affected;
1324                 if ( $indicativeOfReplicaRuntime ) {
1325                         $this->trxWriteAdjDuration += $runtime;
1326                         $this->trxWriteAdjQueryCount += 1;
1327                 }
1328         }
1329
1330         /**
1331          * @param string $sql
1332          * @param string $fname
1333          * @throws DBTransactionStateError
1334          */
1335         private function assertTransactionStatus( $sql, $fname ) {
1336                 if ( $this->getQueryVerb( $sql ) === 'ROLLBACK' ) { // transaction/savepoint
1337                         return;
1338                 }
1339
1340                 if ( $this->trxStatus < self::STATUS_TRX_OK ) {
1341                         throw new DBTransactionStateError(
1342                                 $this,
1343                                 "Cannot execute query from $fname while transaction status is ERROR.",
1344                                 [],
1345                                 $this->trxStatusCause
1346                         );
1347                 } elseif ( $this->trxStatus === self::STATUS_TRX_OK && $this->trxStatusIgnoredCause ) {
1348                         list( $iLastError, $iLastErrno, $iFname ) = $this->trxStatusIgnoredCause;
1349                         call_user_func( $this->deprecationLogger,
1350                                 "Caller from $fname ignored an error originally raised from $iFname: " .
1351                                 "[$iLastErrno] $iLastError"
1352                         );
1353                         $this->trxStatusIgnoredCause = null;
1354                 }
1355         }
1356
1357         public function assertNoOpenTransactions() {
1358                 if ( $this->explicitTrxActive() ) {
1359                         throw new DBTransactionError(
1360                                 $this,
1361                                 "Explicit transaction still active. A caller may have caught an error. "
1362                                 . "Open transactions: " . $this->flatAtomicSectionList()
1363                         );
1364                 }
1365         }
1366
1367         /**
1368          * Determine whether or not it is safe to retry queries after a database
1369          * connection is lost
1370          *
1371          * @param string $sql SQL query
1372          * @param bool $priorWritesPending Whether there is a transaction open with
1373          *     possible write queries or transaction pre-commit/idle callbacks
1374          *     waiting on it to finish.
1375          * @return bool True if it is safe to retry the query, false otherwise
1376          */
1377         private function canRecoverFromDisconnect( $sql, $priorWritesPending ) {
1378                 # Transaction dropped; this can mean lost writes, or REPEATABLE-READ snapshots.
1379                 # Dropped connections also mean that named locks are automatically released.
1380                 # Only allow error suppression in autocommit mode or when the lost transaction
1381                 # didn't matter anyway (aside from DBO_TRX snapshot loss).
1382                 if ( $this->namedLocksHeld ) {
1383                         return false; // possible critical section violation
1384                 } elseif ( $this->sessionTempTables ) {
1385                         return false; // tables might be queried latter
1386                 } elseif ( $sql === 'COMMIT' ) {
1387                         return !$priorWritesPending; // nothing written anyway? (T127428)
1388                 } elseif ( $sql === 'ROLLBACK' ) {
1389                         return true; // transaction lost...which is also what was requested :)
1390                 } elseif ( $this->explicitTrxActive() ) {
1391                         return false; // don't drop atomocity and explicit snapshots
1392                 } elseif ( $priorWritesPending ) {
1393                         return false; // prior writes lost from implicit transaction
1394                 }
1395
1396                 return true;
1397         }
1398
1399         /**
1400          * Clean things up after session (and thus transaction) loss
1401          */
1402         private function handleSessionLoss() {
1403                 // Clean up tracking of session-level things...
1404                 // https://dev.mysql.com/doc/refman/5.7/en/implicit-commit.html
1405                 // https://www.postgresql.org/docs/9.2/static/sql-createtable.html (ignoring ON COMMIT)
1406                 $this->sessionTempTables = [];
1407                 // https://dev.mysql.com/doc/refman/5.7/en/miscellaneous-functions.html#function_get-lock
1408                 // https://www.postgresql.org/docs/9.4/static/functions-admin.html#FUNCTIONS-ADVISORY-LOCKS
1409                 $this->namedLocksHeld = [];
1410                 // Session loss implies transaction loss
1411                 $this->handleTransactionLoss();
1412         }
1413
1414         /**
1415          * Clean things up after transaction loss
1416          */
1417         private function handleTransactionLoss() {
1418                 $this->trxLevel = 0;
1419                 $this->trxAtomicCounter = 0;
1420                 $this->trxIdleCallbacks = []; // T67263; transaction already lost
1421                 $this->trxPreCommitCallbacks = []; // T67263; transaction already lost
1422                 try {
1423                         // Handle callbacks in trxEndCallbacks, e.g. onTransactionResolution().
1424                         // If callback suppression is set then the array will remain unhandled.
1425                         $this->runOnTransactionIdleCallbacks( self::TRIGGER_ROLLBACK );
1426                 } catch ( Exception $ex ) {
1427                         // Already logged; move on...
1428                 }
1429                 try {
1430                         // Handle callbacks in trxRecurringCallbacks, e.g. setTransactionListener()
1431                         $this->runTransactionListenerCallbacks( self::TRIGGER_ROLLBACK );
1432                 } catch ( Exception $ex ) {
1433                         // Already logged; move on...
1434                 }
1435         }
1436
1437         /**
1438          * Checks whether the cause of the error is detected to be a timeout.
1439          *
1440          * It returns false by default, and not all engines support detecting this yet.
1441          * If this returns false, it will be treated as a generic query error.
1442          *
1443          * @param string $error Error text
1444          * @param int $errno Error number
1445          * @return bool
1446          */
1447         protected function wasQueryTimeout( $error, $errno ) {
1448                 return false;
1449         }
1450
1451         /**
1452          * Report a query error. Log the error, and if neither the object ignore
1453          * flag nor the $tempIgnore flag is set, throw a DBQueryError.
1454          *
1455          * @param string $error
1456          * @param int $errno
1457          * @param string $sql
1458          * @param string $fname
1459          * @param bool $tempIgnore
1460          * @throws DBQueryError
1461          */
1462         public function reportQueryError( $error, $errno, $sql, $fname, $tempIgnore = false ) {
1463                 if ( $tempIgnore ) {
1464                         $this->queryLogger->debug( "SQL ERROR (ignored): $error\n" );
1465                 } else {
1466                         $exception = $this->makeQueryException( $error, $errno, $sql, $fname );
1467
1468                         throw $exception;
1469                 }
1470         }
1471
1472         /**
1473          * @param string $error
1474          * @param string|int $errno
1475          * @param string $sql
1476          * @param string $fname
1477          * @return DBError
1478          */
1479         private function makeQueryException( $error, $errno, $sql, $fname ) {
1480                 $sql1line = mb_substr( str_replace( "\n", "\\n", $sql ), 0, 5 * 1024 );
1481                 $this->queryLogger->error(
1482                         "{fname}\t{db_server}\t{errno}\t{error}\t{sql1line}",
1483                         $this->getLogContext( [
1484                                 'method' => __METHOD__,
1485                                 'errno' => $errno,
1486                                 'error' => $error,
1487                                 'sql1line' => $sql1line,
1488                                 'fname' => $fname,
1489                         ] )
1490                 );
1491                 $this->queryLogger->debug( "SQL ERROR: " . $error . "\n" );
1492                 $wasQueryTimeout = $this->wasQueryTimeout( $error, $errno );
1493                 if ( $wasQueryTimeout ) {
1494                         $e = new DBQueryTimeoutError( $this, $error, $errno, $sql, $fname );
1495                 } else {
1496                         $e = new DBQueryError( $this, $error, $errno, $sql, $fname );
1497                 }
1498
1499                 return $e;
1500         }
1501
1502         public function freeResult( $res ) {
1503         }
1504
1505         public function selectField(
1506                 $table, $var, $cond = '', $fname = __METHOD__, $options = [], $join_conds = []
1507         ) {
1508                 if ( $var === '*' ) { // sanity
1509                         throw new DBUnexpectedError( $this, "Cannot use a * field: got '$var'" );
1510                 }
1511
1512                 if ( !is_array( $options ) ) {
1513                         $options = [ $options ];
1514                 }
1515
1516                 $options['LIMIT'] = 1;
1517
1518                 $res = $this->select( $table, $var, $cond, $fname, $options, $join_conds );
1519                 if ( $res === false || !$this->numRows( $res ) ) {
1520                         return false;
1521                 }
1522
1523                 $row = $this->fetchRow( $res );
1524
1525                 if ( $row !== false ) {
1526                         return reset( $row );
1527                 } else {
1528                         return false;
1529                 }
1530         }
1531
1532         public function selectFieldValues(
1533                 $table, $var, $cond = '', $fname = __METHOD__, $options = [], $join_conds = []
1534         ) {
1535                 if ( $var === '*' ) { // sanity
1536                         throw new DBUnexpectedError( $this, "Cannot use a * field" );
1537                 } elseif ( !is_string( $var ) ) { // sanity
1538                         throw new DBUnexpectedError( $this, "Cannot use an array of fields" );
1539                 }
1540
1541                 if ( !is_array( $options ) ) {
1542                         $options = [ $options ];
1543                 }
1544
1545                 $res = $this->select( $table, $var, $cond, $fname, $options, $join_conds );
1546                 if ( $res === false ) {
1547                         return false;
1548                 }
1549
1550                 $values = [];
1551                 foreach ( $res as $row ) {
1552                         $values[] = $row->$var;
1553                 }
1554
1555                 return $values;
1556         }
1557
1558         /**
1559          * Returns an optional USE INDEX clause to go after the table, and a
1560          * string to go at the end of the query.
1561          *
1562          * @param array $options Associative array of options to be turned into
1563          *   an SQL query, valid keys are listed in the function.
1564          * @return array
1565          * @see Database::select()
1566          */
1567         protected function makeSelectOptions( $options ) {
1568                 $preLimitTail = $postLimitTail = '';
1569                 $startOpts = '';
1570
1571                 $noKeyOptions = [];
1572
1573                 foreach ( $options as $key => $option ) {
1574                         if ( is_numeric( $key ) ) {
1575                                 $noKeyOptions[$option] = true;
1576                         }
1577                 }
1578
1579                 $preLimitTail .= $this->makeGroupByWithHaving( $options );
1580
1581                 $preLimitTail .= $this->makeOrderBy( $options );
1582
1583                 if ( isset( $noKeyOptions['FOR UPDATE'] ) ) {
1584                         $postLimitTail .= ' FOR UPDATE';
1585                 }
1586
1587                 if ( isset( $noKeyOptions['LOCK IN SHARE MODE'] ) ) {
1588                         $postLimitTail .= ' LOCK IN SHARE MODE';
1589                 }
1590
1591                 if ( isset( $noKeyOptions['DISTINCT'] ) || isset( $noKeyOptions['DISTINCTROW'] ) ) {
1592                         $startOpts .= 'DISTINCT';
1593                 }
1594
1595                 # Various MySQL extensions
1596                 if ( isset( $noKeyOptions['STRAIGHT_JOIN'] ) ) {
1597                         $startOpts .= ' /*! STRAIGHT_JOIN */';
1598                 }
1599
1600                 if ( isset( $noKeyOptions['HIGH_PRIORITY'] ) ) {
1601                         $startOpts .= ' HIGH_PRIORITY';
1602                 }
1603
1604                 if ( isset( $noKeyOptions['SQL_BIG_RESULT'] ) ) {
1605                         $startOpts .= ' SQL_BIG_RESULT';
1606                 }
1607
1608                 if ( isset( $noKeyOptions['SQL_BUFFER_RESULT'] ) ) {
1609                         $startOpts .= ' SQL_BUFFER_RESULT';
1610                 }
1611
1612                 if ( isset( $noKeyOptions['SQL_SMALL_RESULT'] ) ) {
1613                         $startOpts .= ' SQL_SMALL_RESULT';
1614                 }
1615
1616                 if ( isset( $noKeyOptions['SQL_CALC_FOUND_ROWS'] ) ) {
1617                         $startOpts .= ' SQL_CALC_FOUND_ROWS';
1618                 }
1619
1620                 if ( isset( $noKeyOptions['SQL_CACHE'] ) ) {
1621                         $startOpts .= ' SQL_CACHE';
1622                 }
1623
1624                 if ( isset( $noKeyOptions['SQL_NO_CACHE'] ) ) {
1625                         $startOpts .= ' SQL_NO_CACHE';
1626                 }
1627
1628                 if ( isset( $options['USE INDEX'] ) && is_string( $options['USE INDEX'] ) ) {
1629                         $useIndex = $this->useIndexClause( $options['USE INDEX'] );
1630                 } else {
1631                         $useIndex = '';
1632                 }
1633                 if ( isset( $options['IGNORE INDEX'] ) && is_string( $options['IGNORE INDEX'] ) ) {
1634                         $ignoreIndex = $this->ignoreIndexClause( $options['IGNORE INDEX'] );
1635                 } else {
1636                         $ignoreIndex = '';
1637                 }
1638
1639                 return [ $startOpts, $useIndex, $preLimitTail, $postLimitTail, $ignoreIndex ];
1640         }
1641
1642         /**
1643          * Returns an optional GROUP BY with an optional HAVING
1644          *
1645          * @param array $options Associative array of options
1646          * @return string
1647          * @see Database::select()
1648          * @since 1.21
1649          */
1650         protected function makeGroupByWithHaving( $options ) {
1651                 $sql = '';
1652                 if ( isset( $options['GROUP BY'] ) ) {
1653                         $gb = is_array( $options['GROUP BY'] )
1654                                 ? implode( ',', $options['GROUP BY'] )
1655                                 : $options['GROUP BY'];
1656                         $sql .= ' GROUP BY ' . $gb;
1657                 }
1658                 if ( isset( $options['HAVING'] ) ) {
1659                         $having = is_array( $options['HAVING'] )
1660                                 ? $this->makeList( $options['HAVING'], self::LIST_AND )
1661                                 : $options['HAVING'];
1662                         $sql .= ' HAVING ' . $having;
1663                 }
1664
1665                 return $sql;
1666         }
1667
1668         /**
1669          * Returns an optional ORDER BY
1670          *
1671          * @param array $options Associative array of options
1672          * @return string
1673          * @see Database::select()
1674          * @since 1.21
1675          */
1676         protected function makeOrderBy( $options ) {
1677                 if ( isset( $options['ORDER BY'] ) ) {
1678                         $ob = is_array( $options['ORDER BY'] )
1679                                 ? implode( ',', $options['ORDER BY'] )
1680                                 : $options['ORDER BY'];
1681
1682                         return ' ORDER BY ' . $ob;
1683                 }
1684
1685                 return '';
1686         }
1687
1688         public function select(
1689                 $table, $vars, $conds = '', $fname = __METHOD__, $options = [], $join_conds = []
1690         ) {
1691                 $sql = $this->selectSQLText( $table, $vars, $conds, $fname, $options, $join_conds );
1692
1693                 return $this->query( $sql, $fname );
1694         }
1695
1696         public function selectSQLText( $table, $vars, $conds = '', $fname = __METHOD__,
1697                 $options = [], $join_conds = []
1698         ) {
1699                 if ( is_array( $vars ) ) {
1700                         $fields = implode( ',', $this->fieldNamesWithAlias( $vars ) );
1701                 } else {
1702                         $fields = $vars;
1703                 }
1704
1705                 $options = (array)$options;
1706                 $useIndexes = ( isset( $options['USE INDEX'] ) && is_array( $options['USE INDEX'] ) )
1707                         ? $options['USE INDEX']
1708                         : [];
1709                 $ignoreIndexes = (
1710                         isset( $options['IGNORE INDEX'] ) &&
1711                         is_array( $options['IGNORE INDEX'] )
1712                 )
1713                         ? $options['IGNORE INDEX']
1714                         : [];
1715
1716                 if (
1717                         $this->selectOptionsIncludeLocking( $options ) &&
1718                         $this->selectFieldsOrOptionsAggregate( $vars, $options )
1719                 ) {
1720                         // Some DB types (postgres/oracle) disallow FOR UPDATE with aggregate
1721                         // functions. Discourage use of such queries to encourage compatibility.
1722                         call_user_func(
1723                                 $this->deprecationLogger,
1724                                 __METHOD__ . ": aggregation used with a locking SELECT ($fname)."
1725                         );
1726                 }
1727
1728                 if ( is_array( $table ) ) {
1729                         $from = ' FROM ' .
1730                                 $this->tableNamesWithIndexClauseOrJOIN(
1731                                         $table, $useIndexes, $ignoreIndexes, $join_conds );
1732                 } elseif ( $table != '' ) {
1733                         $from = ' FROM ' .
1734                                 $this->tableNamesWithIndexClauseOrJOIN(
1735                                         [ $table ], $useIndexes, $ignoreIndexes, [] );
1736                 } else {
1737                         $from = '';
1738                 }
1739
1740                 list( $startOpts, $useIndex, $preLimitTail, $postLimitTail, $ignoreIndex ) =
1741                         $this->makeSelectOptions( $options );
1742
1743                 if ( is_array( $conds ) ) {
1744                         $conds = $this->makeList( $conds, self::LIST_AND );
1745                 }
1746
1747                 if ( $conds === null || $conds === false ) {
1748                         $this->queryLogger->warning(
1749                                 __METHOD__
1750                                 . ' called from '
1751                                 . $fname
1752                                 . ' with incorrect parameters: $conds must be a string or an array'
1753                         );
1754                         $conds = '';
1755                 }
1756
1757                 if ( $conds === '' || $conds === '*' ) {
1758                         $sql = "SELECT $startOpts $fields $from $useIndex $ignoreIndex $preLimitTail";
1759                 } elseif ( is_string( $conds ) ) {
1760                         $sql = "SELECT $startOpts $fields $from $useIndex $ignoreIndex " .
1761                                 "WHERE $conds $preLimitTail";
1762                 } else {
1763                         throw new DBUnexpectedError( $this, __METHOD__ . ' called with incorrect parameters' );
1764                 }
1765
1766                 if ( isset( $options['LIMIT'] ) ) {
1767                         $sql = $this->limitResult( $sql, $options['LIMIT'],
1768                                 $options['OFFSET'] ?? false );
1769                 }
1770                 $sql = "$sql $postLimitTail";
1771
1772                 if ( isset( $options['EXPLAIN'] ) ) {
1773                         $sql = 'EXPLAIN ' . $sql;
1774                 }
1775
1776                 return $sql;
1777         }
1778
1779         public function selectRow( $table, $vars, $conds, $fname = __METHOD__,
1780                 $options = [], $join_conds = []
1781         ) {
1782                 $options = (array)$options;
1783                 $options['LIMIT'] = 1;
1784                 $res = $this->select( $table, $vars, $conds, $fname, $options, $join_conds );
1785
1786                 if ( $res === false ) {
1787                         return false;
1788                 }
1789
1790                 if ( !$this->numRows( $res ) ) {
1791                         return false;
1792                 }
1793
1794                 $obj = $this->fetchObject( $res );
1795
1796                 return $obj;
1797         }
1798
1799         public function estimateRowCount(
1800                 $table, $var = '*', $conds = '', $fname = __METHOD__, $options = [], $join_conds = []
1801         ) {
1802                 $conds = $this->normalizeConditions( $conds, $fname );
1803                 $column = $this->extractSingleFieldFromList( $var );
1804                 if ( is_string( $column ) && !in_array( $column, [ '*', '1' ] ) ) {
1805                         $conds[] = "$column IS NOT NULL";
1806                 }
1807
1808                 $res = $this->select(
1809                         $table, [ 'rowcount' => 'COUNT(*)' ], $conds, $fname, $options, $join_conds
1810                 );
1811                 $row = $res ? $this->fetchRow( $res ) : [];
1812
1813                 return isset( $row['rowcount'] ) ? (int)$row['rowcount'] : 0;
1814         }
1815
1816         public function selectRowCount(
1817                 $tables, $var = '*', $conds = '', $fname = __METHOD__, $options = [], $join_conds = []
1818         ) {
1819                 $conds = $this->normalizeConditions( $conds, $fname );
1820                 $column = $this->extractSingleFieldFromList( $var );
1821                 if ( is_string( $column ) && !in_array( $column, [ '*', '1' ] ) ) {
1822                         $conds[] = "$column IS NOT NULL";
1823                 }
1824
1825                 $res = $this->select(
1826                         [
1827                                 'tmp_count' => $this->buildSelectSubquery(
1828                                         $tables,
1829                                         '1',
1830                                         $conds,
1831                                         $fname,
1832                                         $options,
1833                                         $join_conds
1834                                 )
1835                         ],
1836                         [ 'rowcount' => 'COUNT(*)' ],
1837                         [],
1838                         $fname
1839                 );
1840                 $row = $res ? $this->fetchRow( $res ) : [];
1841
1842                 return isset( $row['rowcount'] ) ? (int)$row['rowcount'] : 0;
1843         }
1844
1845         /**
1846          * @param string|array $options
1847          * @return bool
1848          */
1849         private function selectOptionsIncludeLocking( $options ) {
1850                 $options = (array)$options;
1851                 foreach ( [ 'FOR UPDATE', 'LOCK IN SHARE MODE' ] as $lock ) {
1852                         if ( in_array( $lock, $options, true ) ) {
1853                                 return true;
1854                         }
1855                 }
1856
1857                 return false;
1858         }
1859
1860         /**
1861          * @param array|string $fields
1862          * @param array|string $options
1863          * @return bool
1864          */
1865         private function selectFieldsOrOptionsAggregate( $fields, $options ) {
1866                 foreach ( (array)$options as $key => $value ) {
1867                         if ( is_string( $key ) ) {
1868                                 if ( preg_match( '/^(?:GROUP BY|HAVING)$/i', $key ) ) {
1869                                         return true;
1870                                 }
1871                         } elseif ( is_string( $value ) ) {
1872                                 if ( preg_match( '/^(?:DISTINCT|DISTINCTROW)$/i', $value ) ) {
1873                                         return true;
1874                                 }
1875                         }
1876                 }
1877
1878                 $regex = '/^(?:COUNT|MIN|MAX|SUM|GROUP_CONCAT|LISTAGG|ARRAY_AGG)\s*\\(/i';
1879                 foreach ( (array)$fields as $field ) {
1880                         if ( is_string( $field ) && preg_match( $regex, $field ) ) {
1881                                 return true;
1882                         }
1883                 }
1884
1885                 return false;
1886         }
1887
1888         /**
1889          * @param array|string $conds
1890          * @param string $fname
1891          * @return array
1892          */
1893         final protected function normalizeConditions( $conds, $fname ) {
1894                 if ( $conds === null || $conds === false ) {
1895                         $this->queryLogger->warning(
1896                                 __METHOD__
1897                                 . ' called from '
1898                                 . $fname
1899                                 . ' with incorrect parameters: $conds must be a string or an array'
1900                         );
1901                         $conds = '';
1902                 }
1903
1904                 if ( !is_array( $conds ) ) {
1905                         $conds = ( $conds === '' ) ? [] : [ $conds ];
1906                 }
1907
1908                 return $conds;
1909         }
1910
1911         /**
1912          * @param array|string $var Field parameter in the style of select()
1913          * @return string|null Column name or null; ignores aliases
1914          * @throws DBUnexpectedError Errors out if multiple columns are given
1915          */
1916         final protected function extractSingleFieldFromList( $var ) {
1917                 if ( is_array( $var ) ) {
1918                         if ( !$var ) {
1919                                 $column = null;
1920                         } elseif ( count( $var ) == 1 ) {
1921                                 $column = $var[0] ?? reset( $var );
1922                         } else {
1923                                 throw new DBUnexpectedError( $this, __METHOD__ . ': got multiple columns.' );
1924                         }
1925                 } else {
1926                         $column = $var;
1927                 }
1928
1929                 return $column;
1930         }
1931
1932         public function lockForUpdate(
1933                 $table, $conds = '', $fname = __METHOD__, $options = [], $join_conds = []
1934         ) {
1935                 if ( !$this->trxLevel && !$this->getFlag( self::DBO_TRX ) ) {
1936                         throw new DBUnexpectedError(
1937                                 $this,
1938                                 __METHOD__ . ': no transaction is active nor is DBO_TRX set'
1939                         );
1940                 }
1941
1942                 $options = (array)$options;
1943                 $options[] = 'FOR UPDATE';
1944
1945                 return $this->selectRowCount( $table, '*', $conds, $fname, $options, $join_conds );
1946         }
1947
1948         /**
1949          * Removes most variables from an SQL query and replaces them with X or N for numbers.
1950          * It's only slightly flawed. Don't use for anything important.
1951          *
1952          * @param string $sql A SQL Query
1953          *
1954          * @return string
1955          */
1956         protected static function generalizeSQL( $sql ) {
1957                 # This does the same as the regexp below would do, but in such a way
1958                 # as to avoid crashing php on some large strings.
1959                 # $sql = preg_replace( "/'([^\\\\']|\\\\.)*'|\"([^\\\\\"]|\\\\.)*\"/", "'X'", $sql );
1960
1961                 $sql = str_replace( "\\\\", '', $sql );
1962                 $sql = str_replace( "\\'", '', $sql );
1963                 $sql = str_replace( "\\\"", '', $sql );
1964                 $sql = preg_replace( "/'.*'/s", "'X'", $sql );
1965                 $sql = preg_replace( '/".*"/s', "'X'", $sql );
1966
1967                 # All newlines, tabs, etc replaced by single space
1968                 $sql = preg_replace( '/\s+/', ' ', $sql );
1969
1970                 # All numbers => N,
1971                 # except the ones surrounded by characters, e.g. l10n
1972                 $sql = preg_replace( '/-?\d+(,-?\d+)+/s', 'N,...,N', $sql );
1973                 $sql = preg_replace( '/(?<![a-zA-Z])-?\d+(?![a-zA-Z])/s', 'N', $sql );
1974
1975                 return $sql;
1976         }
1977
1978         public function fieldExists( $table, $field, $fname = __METHOD__ ) {
1979                 $info = $this->fieldInfo( $table, $field );
1980
1981                 return (bool)$info;
1982         }
1983
1984         public function indexExists( $table, $index, $fname = __METHOD__ ) {
1985                 if ( !$this->tableExists( $table ) ) {
1986                         return null;
1987                 }
1988
1989                 $info = $this->indexInfo( $table, $index, $fname );
1990                 if ( is_null( $info ) ) {
1991                         return null;
1992                 } else {
1993                         return $info !== false;
1994                 }
1995         }
1996
1997         abstract public function tableExists( $table, $fname = __METHOD__ );
1998
1999         public function indexUnique( $table, $index ) {
2000                 $indexInfo = $this->indexInfo( $table, $index );
2001
2002                 if ( !$indexInfo ) {
2003                         return null;
2004                 }
2005
2006                 return !$indexInfo[0]->Non_unique;
2007         }
2008
2009         /**
2010          * Helper for Database::insert().
2011          *
2012          * @param array $options
2013          * @return string
2014          */
2015         protected function makeInsertOptions( $options ) {
2016                 return implode( ' ', $options );
2017         }
2018
2019         public function insert( $table, $a, $fname = __METHOD__, $options = [] ) {
2020                 # No rows to insert, easy just return now
2021                 if ( !count( $a ) ) {
2022                         return true;
2023                 }
2024
2025                 $table = $this->tableName( $table );
2026
2027                 if ( !is_array( $options ) ) {
2028                         $options = [ $options ];
2029                 }
2030
2031                 $fh = null;
2032                 if ( isset( $options['fileHandle'] ) ) {
2033                         $fh = $options['fileHandle'];
2034                 }
2035                 $options = $this->makeInsertOptions( $options );
2036
2037                 if ( isset( $a[0] ) && is_array( $a[0] ) ) {
2038                         $multi = true;
2039                         $keys = array_keys( $a[0] );
2040                 } else {
2041                         $multi = false;
2042                         $keys = array_keys( $a );
2043                 }
2044
2045                 $sql = 'INSERT ' . $options .
2046                         " INTO $table (" . implode( ',', $keys ) . ') VALUES ';
2047
2048                 if ( $multi ) {
2049                         $first = true;
2050                         foreach ( $a as $row ) {
2051                                 if ( $first ) {
2052                                         $first = false;
2053                                 } else {
2054                                         $sql .= ',';
2055                                 }
2056                                 $sql .= '(' . $this->makeList( $row ) . ')';
2057                         }
2058                 } else {
2059                         $sql .= '(' . $this->makeList( $a ) . ')';
2060                 }
2061
2062                 if ( $fh !== null && false === fwrite( $fh, $sql ) ) {
2063                         return false;
2064                 } elseif ( $fh !== null ) {
2065                         return true;
2066                 }
2067
2068                 return (bool)$this->query( $sql, $fname );
2069         }
2070
2071         /**
2072          * Make UPDATE options array for Database::makeUpdateOptions
2073          *
2074          * @param array $options
2075          * @return array
2076          */
2077         protected function makeUpdateOptionsArray( $options ) {
2078                 if ( !is_array( $options ) ) {
2079                         $options = [ $options ];
2080                 }
2081
2082                 $opts = [];
2083
2084                 if ( in_array( 'IGNORE', $options ) ) {
2085                         $opts[] = 'IGNORE';
2086                 }
2087
2088                 return $opts;
2089         }
2090
2091         /**
2092          * Make UPDATE options for the Database::update function
2093          *
2094          * @param array $options The options passed to Database::update
2095          * @return string
2096          */
2097         protected function makeUpdateOptions( $options ) {
2098                 $opts = $this->makeUpdateOptionsArray( $options );
2099
2100                 return implode( ' ', $opts );
2101         }
2102
2103         public function update( $table, $values, $conds, $fname = __METHOD__, $options = [] ) {
2104                 $table = $this->tableName( $table );
2105                 $opts = $this->makeUpdateOptions( $options );
2106                 $sql = "UPDATE $opts $table SET " . $this->makeList( $values, self::LIST_SET );
2107
2108                 if ( $conds !== [] && $conds !== '*' ) {
2109                         $sql .= " WHERE " . $this->makeList( $conds, self::LIST_AND );
2110                 }
2111
2112                 return (bool)$this->query( $sql, $fname );
2113         }
2114
2115         public function makeList( $a, $mode = self::LIST_COMMA ) {
2116                 if ( !is_array( $a ) ) {
2117                         throw new DBUnexpectedError( $this, __METHOD__ . ' called with incorrect parameters' );
2118                 }
2119
2120                 $first = true;
2121                 $list = '';
2122
2123                 foreach ( $a as $field => $value ) {
2124                         if ( !$first ) {
2125                                 if ( $mode == self::LIST_AND ) {
2126                                         $list .= ' AND ';
2127                                 } elseif ( $mode == self::LIST_OR ) {
2128                                         $list .= ' OR ';
2129                                 } else {
2130                                         $list .= ',';
2131                                 }
2132                         } else {
2133                                 $first = false;
2134                         }
2135
2136                         if ( ( $mode == self::LIST_AND || $mode == self::LIST_OR ) && is_numeric( $field ) ) {
2137                                 $list .= "($value)";
2138                         } elseif ( $mode == self::LIST_SET && is_numeric( $field ) ) {
2139                                 $list .= "$value";
2140                         } elseif (
2141                                 ( $mode == self::LIST_AND || $mode == self::LIST_OR ) && is_array( $value )
2142                         ) {
2143                                 // Remove null from array to be handled separately if found
2144                                 $includeNull = false;
2145                                 foreach ( array_keys( $value, null, true ) as $nullKey ) {
2146                                         $includeNull = true;
2147                                         unset( $value[$nullKey] );
2148                                 }
2149                                 if ( count( $value ) == 0 && !$includeNull ) {
2150                                         throw new InvalidArgumentException(
2151                                                 __METHOD__ . ": empty input for field $field" );
2152                                 } elseif ( count( $value ) == 0 ) {
2153                                         // only check if $field is null
2154                                         $list .= "$field IS NULL";
2155                                 } else {
2156                                         // IN clause contains at least one valid element
2157                                         if ( $includeNull ) {
2158                                                 // Group subconditions to ensure correct precedence
2159                                                 $list .= '(';
2160                                         }
2161                                         if ( count( $value ) == 1 ) {
2162                                                 // Special-case single values, as IN isn't terribly efficient
2163                                                 // Don't necessarily assume the single key is 0; we don't
2164                                                 // enforce linear numeric ordering on other arrays here.
2165                                                 $value = array_values( $value )[0];
2166                                                 $list .= $field . " = " . $this->addQuotes( $value );
2167                                         } else {
2168                                                 $list .= $field . " IN (" . $this->makeList( $value ) . ") ";
2169                                         }
2170                                         // if null present in array, append IS NULL
2171                                         if ( $includeNull ) {
2172                                                 $list .= " OR $field IS NULL)";
2173                                         }
2174                                 }
2175                         } elseif ( $value === null ) {
2176                                 if ( $mode == self::LIST_AND || $mode == self::LIST_OR ) {
2177                                         $list .= "$field IS ";
2178                                 } elseif ( $mode == self::LIST_SET ) {
2179                                         $list .= "$field = ";
2180                                 }
2181                                 $list .= 'NULL';
2182                         } else {
2183                                 if (
2184                                         $mode == self::LIST_AND || $mode == self::LIST_OR || $mode == self::LIST_SET
2185                                 ) {
2186                                         $list .= "$field = ";
2187                                 }
2188                                 $list .= $mode == self::LIST_NAMES ? $value : $this->addQuotes( $value );
2189                         }
2190                 }
2191
2192                 return $list;
2193         }
2194
2195         public function makeWhereFrom2d( $data, $baseKey, $subKey ) {
2196                 $conds = [];
2197
2198                 foreach ( $data as $base => $sub ) {
2199                         if ( count( $sub ) ) {
2200                                 $conds[] = $this->makeList(
2201                                         [ $baseKey => $base, $subKey => array_keys( $sub ) ],
2202                                         self::LIST_AND );
2203                         }
2204                 }
2205
2206                 if ( $conds ) {
2207                         return $this->makeList( $conds, self::LIST_OR );
2208                 } else {
2209                         // Nothing to search for...
2210                         return false;
2211                 }
2212         }
2213
2214         public function aggregateValue( $valuedata, $valuename = 'value' ) {
2215                 return $valuename;
2216         }
2217
2218         public function bitNot( $field ) {
2219                 return "(~$field)";
2220         }
2221
2222         public function bitAnd( $fieldLeft, $fieldRight ) {
2223                 return "($fieldLeft & $fieldRight)";
2224         }
2225
2226         public function bitOr( $fieldLeft, $fieldRight ) {
2227                 return "($fieldLeft | $fieldRight)";
2228         }
2229
2230         public function buildConcat( $stringList ) {
2231                 return 'CONCAT(' . implode( ',', $stringList ) . ')';
2232         }
2233
2234         public function buildGroupConcatField(
2235                 $delim, $table, $field, $conds = '', $join_conds = []
2236         ) {
2237                 $fld = "GROUP_CONCAT($field SEPARATOR " . $this->addQuotes( $delim ) . ')';
2238
2239                 return '(' . $this->selectSQLText( $table, $fld, $conds, null, [], $join_conds ) . ')';
2240         }
2241
2242         public function buildSubstring( $input, $startPosition, $length = null ) {
2243                 $this->assertBuildSubstringParams( $startPosition, $length );
2244                 $functionBody = "$input FROM $startPosition";
2245                 if ( $length !== null ) {
2246                         $functionBody .= " FOR $length";
2247                 }
2248                 return 'SUBSTRING(' . $functionBody . ')';
2249         }
2250
2251         /**
2252          * Check type and bounds for parameters to self::buildSubstring()
2253          *
2254          * All supported databases have substring functions that behave the same for
2255          * positive $startPosition and non-negative $length, but behaviors differ when
2256          * given 0 or negative $startPosition or negative $length. The simplest
2257          * solution to that is to just forbid those values.
2258          *
2259          * @param int $startPosition
2260          * @param int|null $length
2261          * @since 1.31
2262          */
2263         protected function assertBuildSubstringParams( $startPosition, $length ) {
2264                 if ( !is_int( $startPosition ) || $startPosition <= 0 ) {
2265                         throw new InvalidArgumentException(
2266                                 '$startPosition must be a positive integer'
2267                         );
2268                 }
2269                 if ( !( is_int( $length ) && $length >= 0 || $length === null ) ) {
2270                         throw new InvalidArgumentException(
2271                                 '$length must be null or an integer greater than or equal to 0'
2272                         );
2273                 }
2274         }
2275
2276         public function buildStringCast( $field ) {
2277                 return $field;
2278         }
2279
2280         public function buildIntegerCast( $field ) {
2281                 return 'CAST( ' . $field . ' AS INTEGER )';
2282         }
2283
2284         public function buildSelectSubquery(
2285                 $table, $vars, $conds = '', $fname = __METHOD__,
2286                 $options = [], $join_conds = []
2287         ) {
2288                 return new Subquery(
2289                         $this->selectSQLText( $table, $vars, $conds, $fname, $options, $join_conds )
2290                 );
2291         }
2292
2293         public function databasesAreIndependent() {
2294                 return false;
2295         }
2296
2297         final public function selectDB( $db ) {
2298                 $this->selectDomain( new DatabaseDomain(
2299                         $db,
2300                         $this->currentDomain->getSchema(),
2301                         $this->currentDomain->getTablePrefix()
2302                 ) );
2303
2304                 return true;
2305         }
2306
2307         final public function selectDomain( $domain ) {
2308                 $this->doSelectDomain( DatabaseDomain::newFromId( $domain ) );
2309         }
2310
2311         protected function doSelectDomain( DatabaseDomain $domain ) {
2312                 $this->currentDomain = $domain;
2313         }
2314
2315         public function getDBname() {
2316                 return $this->currentDomain->getDatabase();
2317         }
2318
2319         public function getServer() {
2320                 return $this->server;
2321         }
2322
2323         public function tableName( $name, $format = 'quoted' ) {
2324                 if ( $name instanceof Subquery ) {
2325                         throw new DBUnexpectedError(
2326                                 $this,
2327                                 __METHOD__ . ': got Subquery instance when expecting a string.'
2328                         );
2329                 }
2330
2331                 # Skip the entire process when we have a string quoted on both ends.
2332                 # Note that we check the end so that we will still quote any use of
2333                 # use of `database`.table. But won't break things if someone wants
2334                 # to query a database table with a dot in the name.
2335                 if ( $this->isQuotedIdentifier( $name ) ) {
2336                         return $name;
2337                 }
2338
2339                 # Lets test for any bits of text that should never show up in a table
2340                 # name. Basically anything like JOIN or ON which are actually part of
2341                 # SQL queries, but may end up inside of the table value to combine
2342                 # sql. Such as how the API is doing.
2343                 # Note that we use a whitespace test rather than a \b test to avoid
2344                 # any remote case where a word like on may be inside of a table name
2345                 # surrounded by symbols which may be considered word breaks.
2346                 if ( preg_match( '/(^|\s)(DISTINCT|JOIN|ON|AS)(\s|$)/i', $name ) !== 0 ) {
2347                         $this->queryLogger->warning(
2348                                 __METHOD__ . ": use of subqueries is not supported this way.",
2349                                 [ 'trace' => ( new RuntimeException() )->getTraceAsString() ]
2350                         );
2351
2352                         return $name;
2353                 }
2354
2355                 # Split database and table into proper variables.
2356                 list( $database, $schema, $prefix, $table ) = $this->qualifiedTableComponents( $name );
2357
2358                 # Quote $table and apply the prefix if not quoted.
2359                 # $tableName might be empty if this is called from Database::replaceVars()
2360                 $tableName = "{$prefix}{$table}";
2361                 if ( $format === 'quoted'
2362                         && !$this->isQuotedIdentifier( $tableName )
2363                         && $tableName !== ''
2364                 ) {
2365                         $tableName = $this->addIdentifierQuotes( $tableName );
2366                 }
2367
2368                 # Quote $schema and $database and merge them with the table name if needed
2369                 $tableName = $this->prependDatabaseOrSchema( $schema, $tableName, $format );
2370                 $tableName = $this->prependDatabaseOrSchema( $database, $tableName, $format );
2371
2372                 return $tableName;
2373         }
2374
2375         /**
2376          * Get the table components needed for a query given the currently selected database
2377          *
2378          * @param string $name Table name in the form of db.schema.table, db.table, or table
2379          * @return array (DB name or "" for default, schema name, table prefix, table name)
2380          */
2381         protected function qualifiedTableComponents( $name ) {
2382                 # We reverse the explode so that database.table and table both output the correct table.
2383                 $dbDetails = explode( '.', $name, 3 );
2384                 if ( count( $dbDetails ) == 3 ) {
2385                         list( $database, $schema, $table ) = $dbDetails;
2386                         # We don't want any prefix added in this case
2387                         $prefix = '';
2388                 } elseif ( count( $dbDetails ) == 2 ) {
2389                         list( $database, $table ) = $dbDetails;
2390                         # We don't want any prefix added in this case
2391                         $prefix = '';
2392                         # In dbs that support it, $database may actually be the schema
2393                         # but that doesn't affect any of the functionality here
2394                         $schema = '';
2395                 } else {
2396                         list( $table ) = $dbDetails;
2397                         if ( isset( $this->tableAliases[$table] ) ) {
2398                                 $database = $this->tableAliases[$table]['dbname'];
2399                                 $schema = is_string( $this->tableAliases[$table]['schema'] )
2400                                         ? $this->tableAliases[$table]['schema']
2401                                         : $this->relationSchemaQualifier();
2402                                 $prefix = is_string( $this->tableAliases[$table]['prefix'] )
2403                                         ? $this->tableAliases[$table]['prefix']
2404                                         : $this->tablePrefix();
2405                         } else {
2406                                 $database = '';
2407                                 $schema = $this->relationSchemaQualifier(); # Default schema
2408                                 $prefix = $this->tablePrefix(); # Default prefix
2409                         }
2410                 }
2411
2412                 return [ $database, $schema, $prefix, $table ];
2413         }
2414
2415         /**
2416          * @param string|null $namespace Database or schema
2417          * @param string $relation Name of table, view, sequence, etc...
2418          * @param string $format One of (raw, quoted)
2419          * @return string Relation name with quoted and merged $namespace as needed
2420          */
2421         private function prependDatabaseOrSchema( $namespace, $relation, $format ) {
2422                 if ( strlen( $namespace ) ) {
2423                         if ( $format === 'quoted' && !$this->isQuotedIdentifier( $namespace ) ) {
2424                                 $namespace = $this->addIdentifierQuotes( $namespace );
2425                         }
2426                         $relation = $namespace . '.' . $relation;
2427                 }
2428
2429                 return $relation;
2430         }
2431
2432         public function tableNames() {
2433                 $inArray = func_get_args();
2434                 $retVal = [];
2435
2436                 foreach ( $inArray as $name ) {
2437                         $retVal[$name] = $this->tableName( $name );
2438                 }
2439
2440                 return $retVal;
2441         }
2442
2443         public function tableNamesN() {
2444                 $inArray = func_get_args();
2445                 $retVal = [];
2446
2447                 foreach ( $inArray as $name ) {
2448                         $retVal[] = $this->tableName( $name );
2449                 }
2450
2451                 return $retVal;
2452         }
2453
2454         /**
2455          * Get an aliased table name
2456          *
2457          * This returns strings like "tableName AS newTableName" for aliased tables
2458          * and "(SELECT * from tableA) newTablename" for subqueries (e.g. derived tables)
2459          *
2460          * @see Database::tableName()
2461          * @param string|Subquery $table Table name or object with a 'sql' field
2462          * @param string|bool $alias Table alias (optional)
2463          * @return string SQL name for aliased table. Will not alias a table to its own name
2464          */
2465         protected function tableNameWithAlias( $table, $alias = false ) {
2466                 if ( is_string( $table ) ) {
2467                         $quotedTable = $this->tableName( $table );
2468                 } elseif ( $table instanceof Subquery ) {
2469                         $quotedTable = (string)$table;
2470                 } else {
2471                         throw new InvalidArgumentException( "Table must be a string or Subquery." );
2472                 }
2473
2474                 if ( !strlen( $alias ) || $alias === $table ) {
2475                         if ( $table instanceof Subquery ) {
2476                                 throw new InvalidArgumentException( "Subquery table missing alias." );
2477                         }
2478
2479                         return $quotedTable;
2480                 } else {
2481                         return $quotedTable . ' ' . $this->addIdentifierQuotes( $alias );
2482                 }
2483         }
2484
2485         /**
2486          * Gets an array of aliased table names
2487          *
2488          * @param array $tables [ [alias] => table ]
2489          * @return string[] See tableNameWithAlias()
2490          */
2491         protected function tableNamesWithAlias( $tables ) {
2492                 $retval = [];
2493                 foreach ( $tables as $alias => $table ) {
2494                         if ( is_numeric( $alias ) ) {
2495                                 $alias = $table;
2496                         }
2497                         $retval[] = $this->tableNameWithAlias( $table, $alias );
2498                 }
2499
2500                 return $retval;
2501         }
2502
2503         /**
2504          * Get an aliased field name
2505          * e.g. fieldName AS newFieldName
2506          *
2507          * @param string $name Field name
2508          * @param string|bool $alias Alias (optional)
2509          * @return string SQL name for aliased field. Will not alias a field to its own name
2510          */
2511         protected function fieldNameWithAlias( $name, $alias = false ) {
2512                 if ( !$alias || (string)$alias === (string)$name ) {
2513                         return $name;
2514                 } else {
2515                         return $name . ' AS ' . $this->addIdentifierQuotes( $alias ); // PostgreSQL needs AS
2516                 }
2517         }
2518
2519         /**
2520          * Gets an array of aliased field names
2521          *
2522          * @param array $fields [ [alias] => field ]
2523          * @return string[] See fieldNameWithAlias()
2524          */
2525         protected function fieldNamesWithAlias( $fields ) {
2526                 $retval = [];
2527                 foreach ( $fields as $alias => $field ) {
2528                         if ( is_numeric( $alias ) ) {
2529                                 $alias = $field;
2530                         }
2531                         $retval[] = $this->fieldNameWithAlias( $field, $alias );
2532                 }
2533
2534                 return $retval;
2535         }
2536
2537         /**
2538          * Get the aliased table name clause for a FROM clause
2539          * which might have a JOIN and/or USE INDEX or IGNORE INDEX clause
2540          *
2541          * @param array $tables ( [alias] => table )
2542          * @param array $use_index Same as for select()
2543          * @param array $ignore_index Same as for select()
2544          * @param array $join_conds Same as for select()
2545          * @return string
2546          */
2547         protected function tableNamesWithIndexClauseOrJOIN(
2548                 $tables, $use_index = [], $ignore_index = [], $join_conds = []
2549         ) {
2550                 $ret = [];
2551                 $retJOIN = [];
2552                 $use_index = (array)$use_index;
2553                 $ignore_index = (array)$ignore_index;
2554                 $join_conds = (array)$join_conds;
2555
2556                 foreach ( $tables as $alias => $table ) {
2557                         if ( !is_string( $alias ) ) {
2558                                 // No alias? Set it equal to the table name
2559                                 $alias = $table;
2560                         }
2561
2562                         if ( is_array( $table ) ) {
2563                                 // A parenthesized group
2564                                 if ( count( $table ) > 1 ) {
2565                                         $joinedTable = '(' .
2566                                                 $this->tableNamesWithIndexClauseOrJOIN(
2567                                                         $table, $use_index, $ignore_index, $join_conds ) . ')';
2568                                 } else {
2569                                         // Degenerate case
2570                                         $innerTable = reset( $table );
2571                                         $innerAlias = key( $table );
2572                                         $joinedTable = $this->tableNameWithAlias(
2573                                                 $innerTable,
2574                                                 is_string( $innerAlias ) ? $innerAlias : $innerTable
2575                                         );
2576                                 }
2577                         } else {
2578                                 $joinedTable = $this->tableNameWithAlias( $table, $alias );
2579                         }
2580
2581                         // Is there a JOIN clause for this table?
2582                         if ( isset( $join_conds[$alias] ) ) {
2583                                 list( $joinType, $conds ) = $join_conds[$alias];
2584                                 $tableClause = $joinType;
2585                                 $tableClause .= ' ' . $joinedTable;
2586                                 if ( isset( $use_index[$alias] ) ) { // has USE INDEX?
2587                                         $use = $this->useIndexClause( implode( ',', (array)$use_index[$alias] ) );
2588                                         if ( $use != '' ) {
2589                                                 $tableClause .= ' ' . $use;
2590                                         }
2591                                 }
2592                                 if ( isset( $ignore_index[$alias] ) ) { // has IGNORE INDEX?
2593                                         $ignore = $this->ignoreIndexClause(
2594                                                 implode( ',', (array)$ignore_index[$alias] ) );
2595                                         if ( $ignore != '' ) {
2596                                                 $tableClause .= ' ' . $ignore;
2597                                         }
2598                                 }
2599                                 $on = $this->makeList( (array)$conds, self::LIST_AND );
2600                                 if ( $on != '' ) {
2601                                         $tableClause .= ' ON (' . $on . ')';
2602                                 }
2603
2604                                 $retJOIN[] = $tableClause;
2605                         } elseif ( isset( $use_index[$alias] ) ) {
2606                                 // Is there an INDEX clause for this table?
2607                                 $tableClause = $joinedTable;
2608                                 $tableClause .= ' ' . $this->useIndexClause(
2609                                                 implode( ',', (array)$use_index[$alias] )
2610                                         );
2611
2612                                 $ret[] = $tableClause;
2613                         } elseif ( isset( $ignore_index[$alias] ) ) {
2614                                 // Is there an INDEX clause for this table?
2615                                 $tableClause = $joinedTable;
2616                                 $tableClause .= ' ' . $this->ignoreIndexClause(
2617                                                 implode( ',', (array)$ignore_index[$alias] )
2618                                         );
2619
2620                                 $ret[] = $tableClause;
2621                         } else {
2622                                 $tableClause = $joinedTable;
2623
2624                                 $ret[] = $tableClause;
2625                         }
2626                 }
2627
2628                 // We can't separate explicit JOIN clauses with ',', use ' ' for those
2629                 $implicitJoins = $ret ? implode( ',', $ret ) : "";
2630                 $explicitJoins = $retJOIN ? implode( ' ', $retJOIN ) : "";
2631
2632                 // Compile our final table clause
2633                 return implode( ' ', [ $implicitJoins, $explicitJoins ] );
2634         }
2635
2636         /**
2637          * Allows for index remapping in queries where this is not consistent across DBMS
2638          *
2639          * @param string $index
2640          * @return string
2641          */
2642         protected function indexName( $index ) {
2643                 return $this->indexAliases[$index] ?? $index;
2644         }
2645
2646         public function addQuotes( $s ) {
2647                 if ( $s instanceof Blob ) {
2648                         $s = $s->fetch();
2649                 }
2650                 if ( $s === null ) {
2651                         return 'NULL';
2652                 } elseif ( is_bool( $s ) ) {
2653                         return (int)$s;
2654                 } else {
2655                         # This will also quote numeric values. This should be harmless,
2656                         # and protects against weird problems that occur when they really
2657                         # _are_ strings such as article titles and string->number->string
2658                         # conversion is not 1:1.
2659                         return "'" . $this->strencode( $s ) . "'";
2660                 }
2661         }
2662
2663         /**
2664          * Quotes an identifier using `backticks` or "double quotes" depending on the database type.
2665          * MySQL uses `backticks` while basically everything else uses double quotes.
2666          * Since MySQL is the odd one out here the double quotes are our generic
2667          * and we implement backticks in DatabaseMysqlBase.
2668          *
2669          * @param string $s
2670          * @return string
2671          */
2672         public function addIdentifierQuotes( $s ) {
2673                 return '"' . str_replace( '"', '""', $s ) . '"';
2674         }
2675
2676         /**
2677          * Returns if the given identifier looks quoted or not according to
2678          * the database convention for quoting identifiers .
2679          *
2680          * @note Do not use this to determine if untrusted input is safe.
2681          *   A malicious user can trick this function.
2682          * @param string $name
2683          * @return bool
2684          */
2685         public function isQuotedIdentifier( $name ) {
2686                 return $name[0] == '"' && substr( $name, -1, 1 ) == '"';
2687         }
2688
2689         /**
2690          * @param string $s
2691          * @param string $escapeChar
2692          * @return string
2693          */
2694         protected function escapeLikeInternal( $s, $escapeChar = '`' ) {
2695                 return str_replace( [ $escapeChar, '%', '_' ],
2696                         [ "{$escapeChar}{$escapeChar}", "{$escapeChar}%", "{$escapeChar}_" ],
2697                         $s );
2698         }
2699
2700         public function buildLike() {
2701                 $params = func_get_args();
2702
2703                 if ( count( $params ) > 0 && is_array( $params[0] ) ) {
2704                         $params = $params[0];
2705                 }
2706
2707                 $s = '';
2708
2709                 // We use ` instead of \ as the default LIKE escape character, since addQuotes()
2710                 // may escape backslashes, creating problems of double escaping. The `
2711                 // character has good cross-DBMS compatibility, avoiding special operators
2712                 // in MS SQL like ^ and %
2713                 $escapeChar = '`';
2714
2715                 foreach ( $params as $value ) {
2716                         if ( $value instanceof LikeMatch ) {
2717                                 $s .= $value->toString();
2718                         } else {
2719                                 $s .= $this->escapeLikeInternal( $value, $escapeChar );
2720                         }
2721                 }
2722
2723                 return ' LIKE ' .
2724                         $this->addQuotes( $s ) . ' ESCAPE ' . $this->addQuotes( $escapeChar ) . ' ';
2725         }
2726
2727         public function anyChar() {
2728                 return new LikeMatch( '_' );
2729         }
2730
2731         public function anyString() {
2732                 return new LikeMatch( '%' );
2733         }
2734
2735         public function nextSequenceValue( $seqName ) {
2736                 return null;
2737         }
2738
2739         /**
2740          * USE INDEX clause. Unlikely to be useful for anything but MySQL. This
2741          * is only needed because a) MySQL must be as efficient as possible due to
2742          * its use on Wikipedia, and b) MySQL 4.0 is kind of dumb sometimes about
2743          * which index to pick. Anyway, other databases might have different
2744          * indexes on a given table. So don't bother overriding this unless you're
2745          * MySQL.
2746          * @param string $index
2747          * @return string
2748          */
2749         public function useIndexClause( $index ) {
2750                 return '';
2751         }
2752
2753         /**
2754          * IGNORE INDEX clause. Unlikely to be useful for anything but MySQL. This
2755          * is only needed because a) MySQL must be as efficient as possible due to
2756          * its use on Wikipedia, and b) MySQL 4.0 is kind of dumb sometimes about
2757          * which index to pick. Anyway, other databases might have different
2758          * indexes on a given table. So don't bother overriding this unless you're
2759          * MySQL.
2760          * @param string $index
2761          * @return string
2762          */
2763         public function ignoreIndexClause( $index ) {
2764                 return '';
2765         }
2766
2767         public function replace( $table, $uniqueIndexes, $rows, $fname = __METHOD__ ) {
2768                 if ( count( $rows ) == 0 ) {
2769                         return;
2770                 }
2771
2772                 // Single row case
2773                 if ( !is_array( reset( $rows ) ) ) {
2774                         $rows = [ $rows ];
2775                 }
2776
2777                 try {
2778                         $this->startAtomic( $fname, self::ATOMIC_CANCELABLE );
2779                         $affectedRowCount = 0;
2780                         foreach ( $rows as $row ) {
2781                                 // Delete rows which collide with this one
2782                                 $indexWhereClauses = [];
2783                                 foreach ( $uniqueIndexes as $index ) {
2784                                         $indexColumns = (array)$index;
2785                                         $indexRowValues = array_intersect_key( $row, array_flip( $indexColumns ) );
2786                                         if ( count( $indexRowValues ) != count( $indexColumns ) ) {
2787                                                 throw new DBUnexpectedError(
2788                                                         $this,
2789                                                         'New record does not provide all values for unique key (' .
2790                                                         implode( ', ', $indexColumns ) . ')'
2791                                                 );
2792                                         } elseif ( in_array( null, $indexRowValues, true ) ) {
2793                                                 throw new DBUnexpectedError(
2794                                                         $this,
2795                                                         'New record has a null value for unique key (' .
2796                                                         implode( ', ', $indexColumns ) . ')'
2797                                                 );
2798                                         }
2799                                         $indexWhereClauses[] = $this->makeList( $indexRowValues, LIST_AND );
2800                                 }
2801
2802                                 if ( $indexWhereClauses ) {
2803                                         $this->delete( $table, $this->makeList( $indexWhereClauses, LIST_OR ), $fname );
2804                                         $affectedRowCount += $this->affectedRows();
2805                                 }
2806
2807                                 // Now insert the row
2808                                 $this->insert( $table, $row, $fname );
2809                                 $affectedRowCount += $this->affectedRows();
2810                         }
2811                         $this->endAtomic( $fname );
2812                         $this->affectedRowCount = $affectedRowCount;
2813                 } catch ( Exception $e ) {
2814                         $this->cancelAtomic( $fname );
2815                         throw $e;
2816                 }
2817         }
2818
2819         /**
2820          * REPLACE query wrapper for MySQL and SQLite, which have a native REPLACE
2821          * statement.
2822          *
2823          * @param string $table Table name
2824          * @param array|string $rows Row(s) to insert
2825          * @param string $fname Caller function name
2826          *
2827          * @return ResultWrapper
2828          */
2829         protected function nativeReplace( $table, $rows, $fname ) {
2830                 $table = $this->tableName( $table );
2831
2832                 # Single row case
2833                 if ( !is_array( reset( $rows ) ) ) {
2834                         $rows = [ $rows ];
2835                 }
2836
2837                 $sql = "REPLACE INTO $table (" . implode( ',', array_keys( $rows[0] ) ) . ') VALUES ';
2838                 $first = true;
2839
2840                 foreach ( $rows as $row ) {
2841                         if ( $first ) {
2842                                 $first = false;
2843                         } else {
2844                                 $sql .= ',';
2845                         }
2846
2847                         $sql .= '(' . $this->makeList( $row ) . ')';
2848                 }
2849
2850                 return $this->query( $sql, $fname );
2851         }
2852
2853         public function upsert( $table, array $rows, array $uniqueIndexes, array $set,
2854                 $fname = __METHOD__
2855         ) {
2856                 if ( !count( $rows ) ) {
2857                         return true; // nothing to do
2858                 }
2859
2860                 if ( !is_array( reset( $rows ) ) ) {
2861                         $rows = [ $rows ];
2862                 }
2863
2864                 if ( count( $uniqueIndexes ) ) {
2865                         $clauses = []; // list WHERE clauses that each identify a single row
2866                         foreach ( $rows as $row ) {
2867                                 foreach ( $uniqueIndexes as $index ) {
2868                                         $index = is_array( $index ) ? $index : [ $index ]; // columns
2869                                         $rowKey = []; // unique key to this row
2870                                         foreach ( $index as $column ) {
2871                                                 $rowKey[$column] = $row[$column];
2872                                         }
2873                                         $clauses[] = $this->makeList( $rowKey, self::LIST_AND );
2874                                 }
2875                         }
2876                         $where = [ $this->makeList( $clauses, self::LIST_OR ) ];
2877                 } else {
2878                         $where = false;
2879                 }
2880
2881                 $affectedRowCount = 0;
2882                 try {
2883                         $this->startAtomic( $fname, self::ATOMIC_CANCELABLE );
2884                         # Update any existing conflicting row(s)
2885                         if ( $where !== false ) {
2886                                 $ok = $this->update( $table, $set, $where, $fname );
2887                                 $affectedRowCount += $this->affectedRows();
2888                         } else {
2889                                 $ok = true;
2890                         }
2891                         # Now insert any non-conflicting row(s)
2892                         $ok = $this->insert( $table, $rows, $fname, [ 'IGNORE' ] ) && $ok;
2893                         $affectedRowCount += $this->affectedRows();
2894                         $this->endAtomic( $fname );
2895                         $this->affectedRowCount = $affectedRowCount;
2896                 } catch ( Exception $e ) {
2897                         $this->cancelAtomic( $fname );
2898                         throw $e;
2899                 }
2900
2901                 return $ok;
2902         }
2903
2904         public function deleteJoin( $delTable, $joinTable, $delVar, $joinVar, $conds,
2905                 $fname = __METHOD__
2906         ) {
2907                 if ( !$conds ) {
2908                         throw new DBUnexpectedError( $this, __METHOD__ . ' called with empty $conds' );
2909                 }
2910
2911                 $delTable = $this->tableName( $delTable );
2912                 $joinTable = $this->tableName( $joinTable );
2913                 $sql = "DELETE FROM $delTable WHERE $delVar IN (SELECT $joinVar FROM $joinTable ";
2914                 if ( $conds != '*' ) {
2915                         $sql .= 'WHERE ' . $this->makeList( $conds, self::LIST_AND );
2916                 }
2917                 $sql .= ')';
2918
2919                 $this->query( $sql, $fname );
2920         }
2921
2922         public function textFieldSize( $table, $field ) {
2923                 $table = $this->tableName( $table );
2924                 $sql = "SHOW COLUMNS FROM $table LIKE \"$field\";";
2925                 $res = $this->query( $sql, __METHOD__ );
2926                 $row = $this->fetchObject( $res );
2927
2928                 $m = [];
2929
2930                 if ( preg_match( '/\((.*)\)/', $row->Type, $m ) ) {
2931                         $size = $m[1];
2932                 } else {
2933                         $size = -1;
2934                 }
2935
2936                 return $size;
2937         }
2938
2939         public function delete( $table, $conds, $fname = __METHOD__ ) {
2940                 if ( !$conds ) {
2941                         throw new DBUnexpectedError( $this, __METHOD__ . ' called with no conditions' );
2942                 }
2943
2944                 $table = $this->tableName( $table );
2945                 $sql = "DELETE FROM $table";
2946
2947                 if ( $conds != '*' ) {
2948                         if ( is_array( $conds ) ) {
2949                                 $conds = $this->makeList( $conds, self::LIST_AND );
2950                         }
2951                         $sql .= ' WHERE ' . $conds;
2952                 }
2953
2954                 return $this->query( $sql, $fname );
2955         }
2956
2957         final public function insertSelect(
2958                 $destTable, $srcTable, $varMap, $conds,
2959                 $fname = __METHOD__, $insertOptions = [], $selectOptions = [], $selectJoinConds = []
2960         ) {
2961                 static $hints = [ 'NO_AUTO_COLUMNS' ];
2962
2963                 $insertOptions = (array)$insertOptions;
2964                 $selectOptions = (array)$selectOptions;
2965
2966                 if ( $this->cliMode && $this->isInsertSelectSafe( $insertOptions, $selectOptions ) ) {
2967                         // For massive migrations with downtime, we don't want to select everything
2968                         // into memory and OOM, so do all this native on the server side if possible.
2969                         return $this->nativeInsertSelect(
2970                                 $destTable,
2971                                 $srcTable,
2972                                 $varMap,
2973                                 $conds,
2974                                 $fname,
2975                                 array_diff( $insertOptions, $hints ),
2976                                 $selectOptions,
2977                                 $selectJoinConds
2978                         );
2979                 }
2980
2981                 return $this->nonNativeInsertSelect(
2982                         $destTable,
2983                         $srcTable,
2984                         $varMap,
2985                         $conds,
2986                         $fname,
2987                         array_diff( $insertOptions, $hints ),
2988                         $selectOptions,
2989                         $selectJoinConds
2990                 );
2991         }
2992
2993         /**
2994          * @param array $insertOptions INSERT options
2995          * @param array $selectOptions SELECT options
2996          * @return bool Whether an INSERT SELECT with these options will be replication safe
2997          * @since 1.31
2998          */
2999         protected function isInsertSelectSafe( array $insertOptions, array $selectOptions ) {
3000                 return true;
3001         }
3002
3003         /**
3004          * Implementation of insertSelect() based on select() and insert()
3005          *
3006          * @see IDatabase::insertSelect()
3007          * @since 1.30
3008          * @param string $destTable
3009          * @param string|array $srcTable
3010          * @param array $varMap
3011          * @param array $conds
3012          * @param string $fname
3013          * @param array $insertOptions
3014          * @param array $selectOptions
3015          * @param array $selectJoinConds
3016          * @return bool
3017          */
3018         protected function nonNativeInsertSelect( $destTable, $srcTable, $varMap, $conds,
3019                 $fname = __METHOD__,
3020                 $insertOptions = [], $selectOptions = [], $selectJoinConds = []
3021         ) {
3022                 // For web requests, do a locking SELECT and then INSERT. This puts the SELECT burden
3023                 // on only the master (without needing row-based-replication). It also makes it easy to
3024                 // know how big the INSERT is going to be.
3025                 $fields = [];
3026                 foreach ( $varMap as $dstColumn => $sourceColumnOrSql ) {
3027                         $fields[] = $this->fieldNameWithAlias( $sourceColumnOrSql, $dstColumn );
3028                 }
3029                 $selectOptions[] = 'FOR UPDATE';
3030                 $res = $this->select(
3031                         $srcTable, implode( ',', $fields ), $conds, $fname, $selectOptions, $selectJoinConds
3032                 );
3033                 if ( !$res ) {
3034                         return false;
3035                 }
3036
3037                 try {
3038                         $affectedRowCount = 0;
3039                         $this->startAtomic( $fname, self::ATOMIC_CANCELABLE );
3040                         $rows = [];
3041                         $ok = true;
3042                         foreach ( $res as $row ) {
3043                                 $rows[] = (array)$row;
3044
3045                                 // Avoid inserts that are too huge
3046                                 if ( count( $rows ) >= $this->nonNativeInsertSelectBatchSize ) {
3047                                         $ok = $this->insert( $destTable, $rows, $fname, $insertOptions );
3048                                         if ( !$ok ) {
3049                                                 break;
3050                                         }
3051                                         $affectedRowCount += $this->affectedRows();
3052                                         $rows = [];
3053                                 }
3054                         }
3055                         if ( $rows && $ok ) {
3056                                 $ok = $this->insert( $destTable, $rows, $fname, $insertOptions );
3057                                 if ( $ok ) {
3058                                         $affectedRowCount += $this->affectedRows();
3059                                 }
3060                         }
3061                         if ( $ok ) {
3062                                 $this->endAtomic( $fname );
3063                                 $this->affectedRowCount = $affectedRowCount;
3064                         } else {
3065                                 $this->cancelAtomic( $fname );
3066                         }
3067                         return $ok;
3068                 } catch ( Exception $e ) {
3069                         $this->cancelAtomic( $fname );
3070                         throw $e;
3071                 }
3072         }
3073
3074         /**
3075          * Native server-side implementation of insertSelect() for situations where
3076          * we don't want to select everything into memory
3077          *
3078          * @see IDatabase::insertSelect()
3079          * @param string $destTable
3080          * @param string|array $srcTable
3081          * @param array $varMap
3082          * @param array $conds
3083          * @param string $fname
3084          * @param array $insertOptions
3085          * @param array $selectOptions
3086          * @param array $selectJoinConds
3087          * @return bool
3088          */
3089         protected function nativeInsertSelect( $destTable, $srcTable, $varMap, $conds,
3090                 $fname = __METHOD__,
3091                 $insertOptions = [], $selectOptions = [], $selectJoinConds = []
3092         ) {
3093                 $destTable = $this->tableName( $destTable );
3094
3095                 if ( !is_array( $insertOptions ) ) {
3096                         $insertOptions = [ $insertOptions ];
3097                 }
3098
3099                 $insertOptions = $this->makeInsertOptions( $insertOptions );
3100
3101                 $selectSql = $this->selectSQLText(
3102                         $srcTable,
3103                         array_values( $varMap ),
3104                         $conds,
3105                         $fname,
3106                         $selectOptions,
3107                         $selectJoinConds
3108                 );
3109
3110                 $sql = "INSERT $insertOptions" .
3111                         " INTO $destTable (" . implode( ',', array_keys( $varMap ) ) . ') ' .
3112                         $selectSql;
3113
3114                 return $this->query( $sql, $fname );
3115         }
3116
3117         /**
3118          * Construct a LIMIT query with optional offset. This is used for query
3119          * pages. The SQL should be adjusted so that only the first $limit rows
3120          * are returned. If $offset is provided as well, then the first $offset
3121          * rows should be discarded, and the next $limit rows should be returned.
3122          * If the result of the query is not ordered, then the rows to be returned
3123          * are theoretically arbitrary.
3124          *
3125          * $sql is expected to be a SELECT, if that makes a difference.
3126          *
3127          * The version provided by default works in MySQL and SQLite. It will very
3128          * likely need to be overridden for most other DBMSes.
3129          *
3130          * @param string $sql SQL query we will append the limit too
3131          * @param int $limit The SQL limit
3132          * @param int|bool $offset The SQL offset (default false)
3133          * @throws DBUnexpectedError
3134          * @return string
3135          */
3136         public function limitResult( $sql, $limit, $offset = false ) {
3137                 if ( !is_numeric( $limit ) ) {
3138                         throw new DBUnexpectedError( $this,
3139                                 "Invalid non-numeric limit passed to limitResult()\n" );
3140                 }
3141
3142                 return "$sql LIMIT "
3143                 . ( ( is_numeric( $offset ) && $offset != 0 ) ? "{$offset}," : "" )
3144                 . "{$limit} ";
3145         }
3146
3147         public function unionSupportsOrderAndLimit() {
3148                 return true; // True for almost every DB supported
3149         }
3150
3151         public function unionQueries( $sqls, $all ) {
3152                 $glue = $all ? ') UNION ALL (' : ') UNION (';
3153
3154                 return '(' . implode( $glue, $sqls ) . ')';
3155         }
3156
3157         public function unionConditionPermutations(
3158                 $table, $vars, array $permute_conds, $extra_conds = '', $fname = __METHOD__,
3159                 $options = [], $join_conds = []
3160         ) {
3161                 // First, build the Cartesian product of $permute_conds
3162                 $conds = [ [] ];
3163                 foreach ( $permute_conds as $field => $values ) {
3164                         if ( !$values ) {
3165                                 // Skip empty $values
3166                                 continue;
3167                         }
3168                         $values = array_unique( $values ); // For sanity
3169                         $newConds = [];
3170                         foreach ( $conds as $cond ) {
3171                                 foreach ( $values as $value ) {
3172                                         $cond[$field] = $value;
3173                                         $newConds[] = $cond; // Arrays are by-value, not by-reference, so this works
3174                                 }
3175                         }
3176                         $conds = $newConds;
3177                 }
3178
3179                 $extra_conds = $extra_conds === '' ? [] : (array)$extra_conds;
3180
3181                 // If there's just one condition and no subordering, hand off to
3182                 // selectSQLText directly.
3183                 if ( count( $conds ) === 1 &&
3184                         ( !isset( $options['INNER ORDER BY'] ) || !$this->unionSupportsOrderAndLimit() )
3185                 ) {
3186                         return $this->selectSQLText(
3187                                 $table, $vars, $conds[0] + $extra_conds, $fname, $options, $join_conds
3188                         );
3189                 }
3190
3191                 // Otherwise, we need to pull out the order and limit to apply after
3192                 // the union. Then build the SQL queries for each set of conditions in
3193                 // $conds. Then union them together (using UNION ALL, because the
3194                 // product *should* already be distinct).
3195                 $orderBy = $this->makeOrderBy( $options );
3196                 $limit = $options['LIMIT'] ?? null;
3197                 $offset = $options['OFFSET'] ?? false;
3198                 $all = empty( $options['NOTALL'] ) && !in_array( 'NOTALL', $options );
3199                 if ( !$this->unionSupportsOrderAndLimit() ) {
3200                         unset( $options['ORDER BY'], $options['LIMIT'], $options['OFFSET'] );
3201                 } else {
3202                         if ( array_key_exists( 'INNER ORDER BY', $options ) ) {
3203                                 $options['ORDER BY'] = $options['INNER ORDER BY'];
3204                         }
3205                         if ( $limit !== null && is_numeric( $offset ) && $offset != 0 ) {
3206                                 // We need to increase the limit by the offset rather than
3207                                 // using the offset directly, otherwise it'll skip incorrectly
3208                                 // in the subqueries.
3209                                 $options['LIMIT'] = $limit + $offset;
3210                                 unset( $options['OFFSET'] );
3211                         }
3212                 }
3213
3214                 $sqls = [];
3215                 foreach ( $conds as $cond ) {
3216                         $sqls[] = $this->selectSQLText(
3217                                 $table, $vars, $cond + $extra_conds, $fname, $options, $join_conds
3218                         );
3219                 }
3220                 $sql = $this->unionQueries( $sqls, $all ) . $orderBy;
3221                 if ( $limit !== null ) {
3222                         $sql = $this->limitResult( $sql, $limit, $offset );
3223                 }
3224
3225                 return $sql;
3226         }
3227
3228         public function conditional( $cond, $trueVal, $falseVal ) {
3229                 if ( is_array( $cond ) ) {
3230                         $cond = $this->makeList( $cond, self::LIST_AND );
3231                 }
3232
3233                 return " (CASE WHEN $cond THEN $trueVal ELSE $falseVal END) ";
3234         }
3235
3236         public function strreplace( $orig, $old, $new ) {
3237                 return "REPLACE({$orig}, {$old}, {$new})";
3238         }
3239
3240         public function getServerUptime() {
3241                 return 0;
3242         }
3243
3244         public function wasDeadlock() {
3245                 return false;
3246         }
3247
3248         public function wasLockTimeout() {
3249                 return false;
3250         }
3251
3252         public function wasConnectionLoss() {
3253                 return $this->wasConnectionError( $this->lastErrno() );
3254         }
3255
3256         public function wasReadOnlyError() {
3257                 return false;
3258         }
3259
3260         public function wasErrorReissuable() {
3261                 return (
3262                         $this->wasDeadlock() ||
3263                         $this->wasLockTimeout() ||
3264                         $this->wasConnectionLoss()
3265                 );
3266         }
3267
3268         /**
3269          * Do not use this method outside of Database/DBError classes
3270          *
3271          * @param int|string $errno
3272          * @return bool Whether the given query error was a connection drop
3273          */
3274         public function wasConnectionError( $errno ) {
3275                 return false;
3276         }
3277
3278         /**
3279          * @return bool Whether it is safe to assume the given error only caused statement rollback
3280          * @note This is for backwards compatibility for callers catching DBError exceptions in
3281          *   order to ignore problems like duplicate key errors or foriegn key violations
3282          * @since 1.31
3283          */
3284         protected function wasKnownStatementRollbackError() {
3285                 return false; // don't know; it could have caused a transaction rollback
3286         }
3287
3288         public function deadlockLoop() {
3289                 $args = func_get_args();
3290                 $function = array_shift( $args );
3291                 $tries = self::DEADLOCK_TRIES;
3292
3293                 $this->begin( __METHOD__ );
3294
3295                 $retVal = null;
3296                 /** @var Exception $e */
3297                 $e = null;
3298                 do {
3299                         try {
3300                                 $retVal = $function( ...$args );
3301                                 break;
3302                         } catch ( DBQueryError $e ) {
3303                                 if ( $this->wasDeadlock() ) {
3304                                         // Retry after a randomized delay
3305                                         usleep( mt_rand( self::DEADLOCK_DELAY_MIN, self::DEADLOCK_DELAY_MAX ) );
3306                                 } else {
3307                                         // Throw the error back up
3308                                         throw $e;
3309                                 }
3310                         }
3311                 } while ( --$tries > 0 );
3312
3313                 if ( $tries <= 0 ) {
3314                         // Too many deadlocks; give up
3315                         $this->rollback( __METHOD__ );
3316                         throw $e;
3317                 } else {
3318                         $this->commit( __METHOD__ );
3319
3320                         return $retVal;
3321                 }
3322         }
3323
3324         public function masterPosWait( DBMasterPos $pos, $timeout ) {
3325                 # Real waits are implemented in the subclass.
3326                 return 0;
3327         }
3328
3329         public function getReplicaPos() {
3330                 # Stub
3331                 return false;
3332         }
3333
3334         public function getMasterPos() {
3335                 # Stub
3336                 return false;
3337         }
3338
3339         public function serverIsReadOnly() {
3340                 return false;
3341         }
3342
3343         final public function onTransactionResolution( callable $callback, $fname = __METHOD__ ) {
3344                 if ( !$this->trxLevel ) {
3345                         throw new DBUnexpectedError( $this, "No transaction is active." );
3346                 }
3347                 $this->trxEndCallbacks[] = [ $callback, $fname, $this->currentAtomicSectionId() ];
3348         }
3349
3350         final public function onTransactionCommitOrIdle( callable $callback, $fname = __METHOD__ ) {
3351                 if ( !$this->trxLevel && $this->getTransactionRoundId() ) {
3352                         // Start an implicit transaction similar to how query() does
3353                         $this->begin( __METHOD__, self::TRANSACTION_INTERNAL );
3354                         $this->trxAutomatic = true;
3355                 }
3356
3357                 $this->trxIdleCallbacks[] = [ $callback, $fname, $this->currentAtomicSectionId() ];
3358                 if ( !$this->trxLevel ) {
3359                         $this->runOnTransactionIdleCallbacks( self::TRIGGER_IDLE );
3360                 }
3361         }
3362
3363         final public function onTransactionIdle( callable $callback, $fname = __METHOD__ ) {
3364                 $this->onTransactionCommitOrIdle( $callback, $fname );
3365         }
3366
3367         final public function onTransactionPreCommitOrIdle( callable $callback, $fname = __METHOD__ ) {
3368                 if ( !$this->trxLevel && $this->getTransactionRoundId() ) {
3369                         // Start an implicit transaction similar to how query() does
3370                         $this->begin( __METHOD__, self::TRANSACTION_INTERNAL );
3371                         $this->trxAutomatic = true;
3372                 }
3373
3374                 if ( $this->trxLevel ) {
3375                         $this->trxPreCommitCallbacks[] = [ $callback, $fname, $this->currentAtomicSectionId() ];
3376                 } else {
3377                         // No transaction is active nor will start implicitly, so make one for this callback
3378                         $this->startAtomic( __METHOD__, self::ATOMIC_CANCELABLE );
3379                         try {
3380                                 $callback( $this );
3381                                 $this->endAtomic( __METHOD__ );
3382                         } catch ( Exception $e ) {
3383                                 $this->cancelAtomic( __METHOD__ );
3384                                 throw $e;
3385                         }
3386                 }
3387         }
3388
3389         /**
3390          * @return AtomicSectionIdentifier|null ID of the topmost atomic section level
3391          */
3392         private function currentAtomicSectionId() {
3393                 if ( $this->trxLevel && $this->trxAtomicLevels ) {
3394                         $levelInfo = end( $this->trxAtomicLevels );
3395
3396                         return $levelInfo[1];
3397                 }
3398
3399                 return null;
3400         }
3401
3402         /**
3403          * @param AtomicSectionIdentifier $old
3404          * @param AtomicSectionIdentifier $new
3405          */
3406         private function reassignCallbacksForSection(
3407                 AtomicSectionIdentifier $old, AtomicSectionIdentifier $new
3408         ) {
3409                 foreach ( $this->trxPreCommitCallbacks as $key => $info ) {
3410                         if ( $info[2] === $old ) {
3411                                 $this->trxPreCommitCallbacks[$key][2] = $new;
3412                         }
3413                 }
3414                 foreach ( $this->trxIdleCallbacks as $key => $info ) {
3415                         if ( $info[2] === $old ) {
3416                                 $this->trxIdleCallbacks[$key][2] = $new;
3417                         }
3418                 }
3419                 foreach ( $this->trxEndCallbacks as $key => $info ) {
3420                         if ( $info[2] === $old ) {
3421                                 $this->trxEndCallbacks[$key][2] = $new;
3422                         }
3423                 }
3424         }
3425
3426         /**
3427          * @param AtomicSectionIdentifier[] $sectionIds ID of an actual savepoint
3428          * @throws UnexpectedValueException
3429          */
3430         private function modifyCallbacksForCancel( array $sectionIds ) {
3431                 // Cancel the "on commit" callbacks owned by this savepoint
3432                 $this->trxIdleCallbacks = array_filter(
3433                         $this->trxIdleCallbacks,
3434                         function ( $entry ) use ( $sectionIds ) {
3435                                 return !in_array( $entry[2], $sectionIds, true );
3436                         }
3437                 );
3438                 $this->trxPreCommitCallbacks = array_filter(
3439                         $this->trxPreCommitCallbacks,
3440                         function ( $entry ) use ( $sectionIds ) {
3441                                 return !in_array( $entry[2], $sectionIds, true );
3442                         }
3443                 );
3444                 // Make "on resolution" callbacks owned by this savepoint to perceive a rollback
3445                 foreach ( $this->trxEndCallbacks as $key => $entry ) {
3446                         if ( in_array( $entry[2], $sectionIds, true ) ) {
3447                                 $callback = $entry[0];
3448                                 $this->trxEndCallbacks[$key][0] = function () use ( $callback ) {
3449                                         return $callback( self::TRIGGER_ROLLBACK, $this );
3450                                 };
3451                         }
3452                 }
3453         }
3454
3455         final public function setTransactionListener( $name, callable $callback = null ) {
3456                 if ( $callback ) {
3457                         $this->trxRecurringCallbacks[$name] = $callback;
3458                 } else {
3459                         unset( $this->trxRecurringCallbacks[$name] );
3460                 }
3461         }
3462
3463         /**
3464          * Whether to disable running of post-COMMIT/ROLLBACK callbacks
3465          *
3466          * This method should not be used outside of Database/LoadBalancer
3467          *
3468          * @param bool $suppress
3469          * @since 1.28
3470          */
3471         final public function setTrxEndCallbackSuppression( $suppress ) {
3472                 $this->trxEndCallbacksSuppressed = $suppress;
3473         }
3474
3475         /**
3476          * Actually consume and run any "on transaction idle/resolution" callbacks.
3477          *
3478          * This method should not be used outside of Database/LoadBalancer
3479          *
3480          * @param int $trigger IDatabase::TRIGGER_* constant
3481          * @return int Number of callbacks attempted
3482          * @since 1.20
3483          * @throws Exception
3484          */
3485         public function runOnTransactionIdleCallbacks( $trigger ) {
3486                 if ( $this->trxLevel ) { // sanity
3487                         throw new DBUnexpectedError( $this, __METHOD__ . ': a transaction is still open.' );
3488                 }
3489
3490                 if ( $this->trxEndCallbacksSuppressed ) {
3491                         return 0;
3492                 }
3493
3494                 $count = 0;
3495                 $autoTrx = $this->getFlag( self::DBO_TRX ); // automatic begin() enabled?
3496                 /** @var Exception $e */
3497                 $e = null; // first exception
3498                 do { // callbacks may add callbacks :)
3499                         $callbacks = array_merge(
3500                                 $this->trxIdleCallbacks,
3501                                 $this->trxEndCallbacks // include "transaction resolution" callbacks
3502                         );
3503                         $this->trxIdleCallbacks = []; // consumed (and recursion guard)
3504                         $this->trxEndCallbacks = []; // consumed (recursion guard)
3505                         foreach ( $callbacks as $callback ) {
3506                                 ++$count;
3507                                 list( $phpCallback ) = $callback;
3508                                 $this->clearFlag( self::DBO_TRX ); // make each query its own transaction
3509                                 try {
3510                                         call_user_func( $phpCallback, $trigger, $this );
3511                                 } catch ( Exception $ex ) {
3512                                         call_user_func( $this->errorLogger, $ex );
3513                                         $e = $e ?: $ex;
3514                                         // Some callbacks may use startAtomic/endAtomic, so make sure
3515                                         // their transactions are ended so other callbacks don't fail
3516                                         if ( $this->trxLevel() ) {
3517                                                 $this->rollback( __METHOD__, self::FLUSHING_INTERNAL );
3518                                         }
3519                                 } finally {
3520                                         if ( $autoTrx ) {
3521                                                 $this->setFlag( self::DBO_TRX ); // restore automatic begin()
3522                                         } else {
3523                                                 $this->clearFlag( self::DBO_TRX ); // restore auto-commit
3524                                         }
3525                                 }
3526                         }
3527                 } while ( count( $this->trxIdleCallbacks ) );
3528
3529                 if ( $e instanceof Exception ) {
3530                         throw $e; // re-throw any first exception
3531                 }
3532
3533                 return $count;
3534         }
3535
3536         /**
3537          * Actually consume and run any "on transaction pre-commit" callbacks.
3538          *
3539          * This method should not be used outside of Database/LoadBalancer
3540          *
3541          * @since 1.22
3542          * @return int Number of callbacks attempted
3543          * @throws Exception
3544          */
3545         public function runOnTransactionPreCommitCallbacks() {
3546                 $count = 0;
3547
3548                 $e = null; // first exception
3549                 do { // callbacks may add callbacks :)
3550                         $callbacks = $this->trxPreCommitCallbacks;
3551                         $this->trxPreCommitCallbacks = []; // consumed (and recursion guard)
3552                         foreach ( $callbacks as $callback ) {
3553                                 try {
3554                                         ++$count;
3555                                         list( $phpCallback ) = $callback;
3556                                         $phpCallback( $this );
3557                                 } catch ( Exception $ex ) {
3558                                         ( $this->errorLogger )( $ex );
3559                                         $e = $e ?: $ex;
3560                                 }
3561                         }
3562                 } while ( count( $this->trxPreCommitCallbacks ) );
3563
3564                 if ( $e instanceof Exception ) {
3565                         throw $e; // re-throw any first exception
3566                 }
3567
3568                 return $count;
3569         }
3570
3571         /**
3572          * Actually run any "transaction listener" callbacks.
3573          *
3574          * This method should not be used outside of Database/LoadBalancer
3575          *
3576          * @param int $trigger IDatabase::TRIGGER_* constant
3577          * @throws Exception
3578          * @since 1.20
3579          */
3580         public function runTransactionListenerCallbacks( $trigger ) {
3581                 if ( $this->trxEndCallbacksSuppressed ) {
3582                         return;
3583                 }
3584
3585                 /** @var Exception $e */
3586                 $e = null; // first exception
3587
3588                 foreach ( $this->trxRecurringCallbacks as $phpCallback ) {
3589                         try {
3590                                 $phpCallback( $trigger, $this );
3591                         } catch ( Exception $ex ) {
3592                                 ( $this->errorLogger )( $ex );
3593                                 $e = $e ?: $ex;
3594                         }
3595                 }
3596
3597                 if ( $e instanceof Exception ) {
3598                         throw $e; // re-throw any first exception
3599                 }
3600         }
3601
3602         /**
3603          * Create a savepoint
3604          *
3605          * This is used internally to implement atomic sections. It should not be
3606          * used otherwise.
3607          *
3608          * @since 1.31
3609          * @param string $identifier Identifier for the savepoint
3610          * @param string $fname Calling function name
3611          */
3612         protected function doSavepoint( $identifier, $fname ) {
3613                 $this->query( 'SAVEPOINT ' . $this->addIdentifierQuotes( $identifier ), $fname );
3614         }
3615
3616         /**
3617          * Release a savepoint
3618          *
3619          * This is used internally to implement atomic sections. It should not be
3620          * used otherwise.
3621          *
3622          * @since 1.31
3623          * @param string $identifier Identifier for the savepoint
3624          * @param string $fname Calling function name
3625          */
3626         protected function doReleaseSavepoint( $identifier, $fname ) {
3627                 $this->query( 'RELEASE SAVEPOINT ' . $this->addIdentifierQuotes( $identifier ), $fname );
3628         }
3629
3630         /**
3631          * Rollback to a savepoint
3632          *
3633          * This is used internally to implement atomic sections. It should not be
3634          * used otherwise.
3635          *
3636          * @since 1.31
3637          * @param string $identifier Identifier for the savepoint
3638          * @param string $fname Calling function name
3639          */
3640         protected function doRollbackToSavepoint( $identifier, $fname ) {
3641                 $this->query( 'ROLLBACK TO SAVEPOINT ' . $this->addIdentifierQuotes( $identifier ), $fname );
3642         }
3643
3644         /**
3645          * @param string $fname
3646          * @return string
3647          */
3648         private function nextSavepointId( $fname ) {
3649                 $savepointId = self::$SAVEPOINT_PREFIX . ++$this->trxAtomicCounter;
3650                 if ( strlen( $savepointId ) > 30 ) {
3651                         // 30 == Oracle's identifier length limit (pre 12c)
3652                         // With a 22 character prefix, that puts the highest number at 99999999.
3653                         throw new DBUnexpectedError(
3654                                 $this,
3655                                 'There have been an excessively large number of atomic sections in a transaction'
3656                                 . " started by $this->trxFname (at $fname)"
3657                         );
3658                 }
3659
3660                 return $savepointId;
3661         }
3662
3663         final public function startAtomic(
3664                 $fname = __METHOD__, $cancelable = self::ATOMIC_NOT_CANCELABLE
3665         ) {
3666                 $savepointId = $cancelable === self::ATOMIC_CANCELABLE ? self::$NOT_APPLICABLE : null;
3667
3668                 if ( !$this->trxLevel ) {
3669                         $this->begin( $fname, self::TRANSACTION_INTERNAL ); // sets trxAutomatic
3670                         // If DBO_TRX is set, a series of startAtomic/endAtomic pairs will result
3671                         // in all changes being in one transaction to keep requests transactional.
3672                         if ( $this->getFlag( self::DBO_TRX ) ) {
3673                                 // Since writes could happen in between the topmost atomic sections as part
3674                                 // of the transaction, those sections will need savepoints.
3675                                 $savepointId = $this->nextSavepointId( $fname );
3676                                 $this->doSavepoint( $savepointId, $fname );
3677                         } else {
3678                                 $this->trxAutomaticAtomic = true;
3679                         }
3680                 } elseif ( $cancelable === self::ATOMIC_CANCELABLE ) {
3681                         $savepointId = $this->nextSavepointId( $fname );
3682                         $this->doSavepoint( $savepointId, $fname );
3683                 }
3684
3685                 $sectionId = new AtomicSectionIdentifier;
3686                 $this->trxAtomicLevels[] = [ $fname, $sectionId, $savepointId ];
3687
3688                 return $sectionId;
3689         }
3690
3691         final public function endAtomic( $fname = __METHOD__ ) {
3692                 if ( !$this->trxLevel || !$this->trxAtomicLevels ) {
3693                         throw new DBUnexpectedError( $this, "No atomic section is open (got $fname)." );
3694                 }
3695
3696                 // Check if the current section matches $fname
3697                 $pos = count( $this->trxAtomicLevels ) - 1;
3698                 list( $savedFname, $sectionId, $savepointId ) = $this->trxAtomicLevels[$pos];
3699
3700                 if ( $savedFname !== $fname ) {
3701                         throw new DBUnexpectedError(
3702                                 $this,
3703                                 "Invalid atomic section ended (got $fname but expected $savedFname)."
3704                         );
3705                 }
3706
3707                 // Remove the last section (no need to re-index the array)
3708                 array_pop( $this->trxAtomicLevels );
3709
3710                 if ( !$this->trxAtomicLevels && $this->trxAutomaticAtomic ) {
3711                         $this->commit( $fname, self::FLUSHING_INTERNAL );
3712                 } elseif ( $savepointId !== null && $savepointId !== self::$NOT_APPLICABLE ) {
3713                         $this->doReleaseSavepoint( $savepointId, $fname );
3714                 }
3715
3716                 // Hoist callback ownership for callbacks in the section that just ended;
3717                 // all callbacks should have an owner that is present in trxAtomicLevels.
3718                 $currentSectionId = $this->currentAtomicSectionId();
3719                 if ( $currentSectionId ) {
3720                         $this->reassignCallbacksForSection( $sectionId, $currentSectionId );
3721                 }
3722         }
3723
3724         final public function cancelAtomic(
3725                 $fname = __METHOD__, AtomicSectionIdentifier $sectionId = null
3726         ) {
3727                 if ( !$this->trxLevel || !$this->trxAtomicLevels ) {
3728                         throw new DBUnexpectedError( $this, "No atomic section is open (got $fname)." );
3729                 }
3730
3731                 if ( $sectionId !== null ) {
3732                         // Find the (last) section with the given $sectionId
3733                         $pos = -1;
3734                         foreach ( $this->trxAtomicLevels as $i => list( $asFname, $asId, $spId ) ) {
3735                                 if ( $asId === $sectionId ) {
3736                                         $pos = $i;
3737                                 }
3738                         }
3739                         if ( $pos < 0 ) {
3740                                 throw new DBUnexpectedError( "Atomic section not found (for $fname)" );
3741                         }
3742                         // Remove all descendant sections and re-index the array
3743                         $excisedIds = [];
3744                         $len = count( $this->trxAtomicLevels );
3745                         for ( $i = $pos + 1; $i < $len; ++$i ) {
3746                                 $excisedIds[] = $this->trxAtomicLevels[$i][1];
3747                         }
3748                         $this->trxAtomicLevels = array_slice( $this->trxAtomicLevels, 0, $pos + 1 );
3749                         $this->modifyCallbacksForCancel( $excisedIds );
3750                 }
3751
3752                 // Check if the current section matches $fname
3753                 $pos = count( $this->trxAtomicLevels ) - 1;
3754                 list( $savedFname, $savedSectionId, $savepointId ) = $this->trxAtomicLevels[$pos];
3755
3756                 if ( $savedFname !== $fname ) {
3757                         throw new DBUnexpectedError(
3758                                 $this,
3759                                 "Invalid atomic section ended (got $fname but expected $savedFname)."
3760                         );
3761                 }
3762
3763                 // Remove the last section (no need to re-index the array)
3764                 array_pop( $this->trxAtomicLevels );
3765                 $this->modifyCallbacksForCancel( [ $savedSectionId ] );
3766
3767                 if ( $savepointId !== null ) {
3768                         // Rollback the transaction to the state just before this atomic section
3769                         if ( $savepointId === self::$NOT_APPLICABLE ) {
3770                                 $this->rollback( $fname, self::FLUSHING_INTERNAL );
3771                         } else {
3772                                 $this->doRollbackToSavepoint( $savepointId, $fname );
3773                                 $this->trxStatus = self::STATUS_TRX_OK; // no exception; recovered
3774                                 $this->trxStatusIgnoredCause = null;
3775                         }
3776                 } elseif ( $this->trxStatus > self::STATUS_TRX_ERROR ) {
3777                         // Put the transaction into an error state if it's not already in one
3778                         $this->trxStatus = self::STATUS_TRX_ERROR;
3779                         $this->trxStatusCause = new DBUnexpectedError(
3780                                 $this,
3781                                 "Uncancelable atomic section canceled (got $fname)."
3782                         );
3783                 }
3784
3785                 $this->affectedRowCount = 0; // for the sake of consistency
3786         }
3787
3788         final public function doAtomicSection(
3789                 $fname, callable $callback, $cancelable = self::ATOMIC_NOT_CANCELABLE
3790         ) {
3791                 $sectionId = $this->startAtomic( $fname, $cancelable );
3792                 try {
3793                         $res = $callback( $this, $fname );
3794                 } catch ( Exception $e ) {
3795                         $this->cancelAtomic( $fname, $sectionId );
3796
3797                         throw $e;
3798                 }
3799                 $this->endAtomic( $fname );
3800
3801                 return $res;
3802         }
3803
3804         final public function begin( $fname = __METHOD__, $mode = self::TRANSACTION_EXPLICIT ) {
3805                 static $modes = [ self::TRANSACTION_EXPLICIT, self::TRANSACTION_INTERNAL ];
3806                 if ( !in_array( $mode, $modes, true ) ) {
3807                         throw new DBUnexpectedError( $this, "$fname: invalid mode parameter '$mode'." );
3808                 }
3809
3810                 // Protect against mismatched atomic section, transaction nesting, and snapshot loss
3811                 if ( $this->trxLevel ) {
3812                         if ( $this->trxAtomicLevels ) {
3813                                 $levels = $this->flatAtomicSectionList();
3814                                 $msg = "$fname: Got explicit BEGIN while atomic section(s) $levels are open.";
3815                                 throw new DBUnexpectedError( $this, $msg );
3816                         } elseif ( !$this->trxAutomatic ) {
3817                                 $msg = "$fname: Explicit transaction already active (from {$this->trxFname}).";
3818                                 throw new DBUnexpectedError( $this, $msg );
3819                         } else {
3820                                 $msg = "$fname: Implicit transaction already active (from {$this->trxFname}).";
3821                                 throw new DBUnexpectedError( $this, $msg );
3822                         }
3823                 } elseif ( $this->getFlag( self::DBO_TRX ) && $mode !== self::TRANSACTION_INTERNAL ) {
3824                         $msg = "$fname: Implicit transaction expected (DBO_TRX set).";
3825                         throw new DBUnexpectedError( $this, $msg );
3826                 }
3827
3828                 // Avoid fatals if close() was called
3829                 $this->assertOpen();
3830
3831                 $this->doBegin( $fname );
3832                 $this->trxStatus = self::STATUS_TRX_OK;
3833                 $this->trxStatusIgnoredCause = null;
3834                 $this->trxAtomicCounter = 0;
3835                 $this->trxTimestamp = microtime( true );
3836                 $this->trxFname = $fname;
3837                 $this->trxDoneWrites = false;
3838                 $this->trxAutomaticAtomic = false;
3839                 $this->trxAtomicLevels = [];
3840                 $this->trxShortId = sprintf( '%06x', mt_rand( 0, 0xffffff ) );
3841                 $this->trxWriteDuration = 0.0;
3842                 $this->trxWriteQueryCount = 0;
3843                 $this->trxWriteAffectedRows = 0;
3844                 $this->trxWriteAdjDuration = 0.0;
3845                 $this->trxWriteAdjQueryCount = 0;
3846                 $this->trxWriteCallers = [];
3847                 // First SELECT after BEGIN will establish the snapshot in REPEATABLE-READ.
3848                 // Get an estimate of the replication lag before any such queries.
3849                 $this->trxReplicaLag = null; // clear cached value first
3850                 $this->trxReplicaLag = $this->getApproximateLagStatus()['lag'];
3851                 // T147697: make explicitTrxActive() return true until begin() finishes. This way, no
3852                 // caller will think its OK to muck around with the transaction just because startAtomic()
3853                 // has not yet completed (e.g. setting trxAtomicLevels).
3854                 $this->trxAutomatic = ( $mode === self::TRANSACTION_INTERNAL );
3855         }
3856
3857         /**
3858          * Issues the BEGIN command to the database server.
3859          *
3860          * @see Database::begin()
3861          * @param string $fname
3862          */
3863         protected function doBegin( $fname ) {
3864                 $this->query( 'BEGIN', $fname );
3865                 $this->trxLevel = 1;
3866         }
3867
3868         final public function commit( $fname = __METHOD__, $flush = self::FLUSHING_ONE ) {
3869                 static $modes = [ self::FLUSHING_ONE, self::FLUSHING_ALL_PEERS, self::FLUSHING_INTERNAL ];
3870                 if ( !in_array( $flush, $modes, true ) ) {
3871                         throw new DBUnexpectedError( $this, "$fname: invalid flush parameter '$flush'." );
3872                 }
3873
3874                 if ( $this->trxLevel && $this->trxAtomicLevels ) {
3875                         // There are still atomic sections open; this cannot be ignored
3876                         $levels = $this->flatAtomicSectionList();
3877                         throw new DBUnexpectedError(
3878                                 $this,
3879                                 "$fname: Got COMMIT while atomic sections $levels are still open."
3880                         );
3881                 }
3882
3883                 if ( $flush === self::FLUSHING_INTERNAL || $flush === self::FLUSHING_ALL_PEERS ) {
3884                         if ( !$this->trxLevel ) {
3885                                 return; // nothing to do
3886                         } elseif ( !$this->trxAutomatic ) {
3887                                 throw new DBUnexpectedError(
3888                                         $this,
3889                                         "$fname: Flushing an explicit transaction, getting out of sync."
3890                                 );
3891                         }
3892                 } else {
3893                         if ( !$this->trxLevel ) {
3894                                 $this->queryLogger->error(
3895                                         "$fname: No transaction to commit, something got out of sync." );
3896                                 return; // nothing to do
3897                         } elseif ( $this->trxAutomatic ) {
3898                                 throw new DBUnexpectedError(
3899                                         $this,
3900                                         "$fname: Expected mass commit of all peer transactions (DBO_TRX set)."
3901                                 );
3902                         }
3903                 }
3904
3905                 // Avoid fatals if close() was called
3906                 $this->assertOpen();
3907
3908                 $this->runOnTransactionPreCommitCallbacks();
3909
3910                 $writeTime = $this->pendingWriteQueryDuration( self::ESTIMATE_DB_APPLY );
3911                 $this->doCommit( $fname );
3912                 $this->trxStatus = self::STATUS_TRX_NONE;
3913
3914                 if ( $this->trxDoneWrites ) {
3915                         $this->lastWriteTime = microtime( true );
3916                         $this->trxProfiler->transactionWritingOut(
3917                                 $this->server,
3918                                 $this->getDomainID(),
3919                                 $this->trxShortId,
3920                                 $writeTime,
3921                                 $this->trxWriteAffectedRows
3922                         );
3923                 }
3924
3925                 // With FLUSHING_ALL_PEERS, callbacks will be explicitly run later
3926                 if ( $flush !== self::FLUSHING_ALL_PEERS ) {
3927                         $this->runOnTransactionIdleCallbacks( self::TRIGGER_COMMIT );
3928                         $this->runTransactionListenerCallbacks( self::TRIGGER_COMMIT );
3929                 }
3930         }
3931
3932         /**
3933          * Issues the COMMIT command to the database server.
3934          *
3935          * @see Database::commit()
3936          * @param string $fname
3937          */
3938         protected function doCommit( $fname ) {
3939                 if ( $this->trxLevel ) {
3940                         $this->query( 'COMMIT', $fname );
3941                         $this->trxLevel = 0;
3942                 }
3943         }
3944
3945         final public function rollback( $fname = __METHOD__, $flush = '' ) {
3946                 $trxActive = $this->trxLevel;
3947
3948                 if ( $flush !== self::FLUSHING_INTERNAL && $flush !== self::FLUSHING_ALL_PEERS ) {
3949                         if ( $this->getFlag( self::DBO_TRX ) ) {
3950                                 throw new DBUnexpectedError(
3951                                         $this,
3952                                         "$fname: Expected mass rollback of all peer transactions (DBO_TRX set)."
3953                                 );
3954                         }
3955                 }
3956
3957                 if ( $trxActive ) {
3958                         // Avoid fatals if close() was called
3959                         $this->assertOpen();
3960
3961                         $writeTime = $this->pendingWriteQueryDuration( self::ESTIMATE_DB_APPLY );
3962                         $this->doRollback( $fname );
3963                         $this->trxStatus = self::STATUS_TRX_NONE;
3964                         $this->trxAtomicLevels = [];
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|ResultWrapper|resource $result
4081          * @return bool|ResultWrapper
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->rttEstimate > 0 ) {
4100                                 $rtt = $this->rttEstimate;
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->rttEstimate;
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->opened = false;
4126                 $this->conn = false;
4127                 try {
4128                         $this->open(
4129                                 $this->server,
4130                                 $this->user,
4131                                 $this->password,
4132                                 $this->getDBname(),
4133                                 $this->dbSchema(),
4134                                 $this->tablePrefix()
4135                         );
4136                         $this->lastPing = microtime( true );
4137                         $ok = true;
4138
4139                         $this->connLogger->warning(
4140                                 $fname . ': lost connection to {dbserver}; reconnected',
4141                                 [
4142                                         'dbserver' => $this->getServer(),
4143                                         'trace' => ( new RuntimeException() )->getTraceAsString()
4144                                 ]
4145                         );
4146                 } catch ( DBConnectionError $e ) {
4147                         $ok = false;
4148
4149                         $this->connLogger->error(
4150                                 $fname . ': lost connection to {dbserver} permanently',
4151                                 [ 'dbserver' => $this->getServer() ]
4152                         );
4153                 }
4154
4155                 $this->handleSessionLoss();
4156
4157                 return $ok;
4158         }
4159
4160         public function getSessionLagStatus() {
4161                 return $this->getRecordedTransactionLagStatus() ?: $this->getApproximateLagStatus();
4162         }
4163
4164         /**
4165          * Get the replica DB lag when the current transaction started
4166          *
4167          * This is useful when transactions might use snapshot isolation
4168          * (e.g. REPEATABLE-READ in innodb), so the "real" lag of that data
4169          * is this lag plus transaction duration. If they don't, it is still
4170          * safe to be pessimistic. This returns null if there is no transaction.
4171          *
4172          * This returns null if the lag status for this transaction was not yet recorded.
4173          *
4174          * @return array|null ('lag': seconds or false on error, 'since': UNIX timestamp of BEGIN)
4175          * @since 1.27
4176          */
4177         final protected function getRecordedTransactionLagStatus() {
4178                 return ( $this->trxLevel && $this->trxReplicaLag !== null )
4179                         ? [ 'lag' => $this->trxReplicaLag, 'since' => $this->trxTimestamp() ]
4180                         : null;
4181         }
4182
4183         /**
4184          * Get a replica DB lag estimate for this server
4185          *
4186          * @return array ('lag': seconds or false on error, 'since': UNIX timestamp of estimate)
4187          * @since 1.27
4188          */
4189         protected function getApproximateLagStatus() {
4190                 return [
4191                         'lag'   => $this->getLBInfo( 'replica' ) ? $this->getLag() : 0,
4192                         'since' => microtime( true )
4193                 ];
4194         }
4195
4196         /**
4197          * Merge the result of getSessionLagStatus() for several DBs
4198          * using the most pessimistic values to estimate the lag of
4199          * any data derived from them in combination
4200          *
4201          * This is information is useful for caching modules
4202          *
4203          * @see WANObjectCache::set()
4204          * @see WANObjectCache::getWithSetCallback()
4205          *
4206          * @param IDatabase $db1
4207          * @param IDatabase|null $db2 [optional]
4208          * @return array Map of values:
4209          *   - lag: highest lag of any of the DBs or false on error (e.g. replication stopped)
4210          *   - since: oldest UNIX timestamp of any of the DB lag estimates
4211          *   - pending: whether any of the DBs have uncommitted changes
4212          * @throws DBError
4213          * @since 1.27
4214          */
4215         public static function getCacheSetOptions( IDatabase $db1, IDatabase $db2 = null ) {
4216                 $res = [ 'lag' => 0, 'since' => INF, 'pending' => false ];
4217                 foreach ( func_get_args() as $db ) {
4218                         /** @var IDatabase $db */
4219                         $status = $db->getSessionLagStatus();
4220                         if ( $status['lag'] === false ) {
4221                                 $res['lag'] = false;
4222                         } elseif ( $res['lag'] !== false ) {
4223                                 $res['lag'] = max( $res['lag'], $status['lag'] );
4224                         }
4225                         $res['since'] = min( $res['since'], $status['since'] );
4226                         $res['pending'] = $res['pending'] ?: $db->writesPending();
4227                 }
4228
4229                 return $res;
4230         }
4231
4232         public function getLag() {
4233                 return 0;
4234         }
4235
4236         public function maxListLen() {
4237                 return 0;
4238         }
4239
4240         public function encodeBlob( $b ) {
4241                 return $b;
4242         }
4243
4244         public function decodeBlob( $b ) {
4245                 if ( $b instanceof Blob ) {
4246                         $b = $b->fetch();
4247                 }
4248                 return $b;
4249         }
4250
4251         public function setSessionOptions( array $options ) {
4252         }
4253
4254         public function sourceFile(
4255                 $filename,
4256                 callable $lineCallback = null,
4257                 callable $resultCallback = null,
4258                 $fname = false,
4259                 callable $inputCallback = null
4260         ) {
4261                 Wikimedia\suppressWarnings();
4262                 $fp = fopen( $filename, 'r' );
4263                 Wikimedia\restoreWarnings();
4264
4265                 if ( false === $fp ) {
4266                         throw new RuntimeException( "Could not open \"{$filename}\".\n" );
4267                 }
4268
4269                 if ( !$fname ) {
4270                         $fname = __METHOD__ . "( $filename )";
4271                 }
4272
4273                 try {
4274                         $error = $this->sourceStream(
4275                                 $fp, $lineCallback, $resultCallback, $fname, $inputCallback );
4276                 } catch ( Exception $e ) {
4277                         fclose( $fp );
4278                         throw $e;
4279                 }
4280
4281                 fclose( $fp );
4282
4283                 return $error;
4284         }
4285
4286         public function setSchemaVars( $vars ) {
4287                 $this->schemaVars = $vars;
4288         }
4289
4290         public function sourceStream(
4291                 $fp,
4292                 callable $lineCallback = null,
4293                 callable $resultCallback = null,
4294                 $fname = __METHOD__,
4295                 callable $inputCallback = null
4296         ) {
4297                 $delimiterReset = new ScopedCallback(
4298                         function ( $delimiter ) {
4299                                 $this->delimiter = $delimiter;
4300                         },
4301                         [ $this->delimiter ]
4302                 );
4303                 $cmd = '';
4304
4305                 while ( !feof( $fp ) ) {
4306                         if ( $lineCallback ) {
4307                                 call_user_func( $lineCallback );
4308                         }
4309
4310                         $line = trim( fgets( $fp ) );
4311
4312                         if ( $line == '' ) {
4313                                 continue;
4314                         }
4315
4316                         if ( '-' == $line[0] && '-' == $line[1] ) {
4317                                 continue;
4318                         }
4319
4320                         if ( $cmd != '' ) {
4321                                 $cmd .= ' ';
4322                         }
4323
4324                         $done = $this->streamStatementEnd( $cmd, $line );
4325
4326                         $cmd .= "$line\n";
4327
4328                         if ( $done || feof( $fp ) ) {
4329                                 $cmd = $this->replaceVars( $cmd );
4330
4331                                 if ( $inputCallback ) {
4332                                         $callbackResult = $inputCallback( $cmd );
4333
4334                                         if ( is_string( $callbackResult ) || !$callbackResult ) {
4335                                                 $cmd = $callbackResult;
4336                                         }
4337                                 }
4338
4339                                 if ( $cmd ) {
4340                                         $res = $this->query( $cmd, $fname );
4341
4342                                         if ( $resultCallback ) {
4343                                                 $resultCallback( $res, $this );
4344                                         }
4345
4346                                         if ( false === $res ) {
4347                                                 $err = $this->lastError();
4348
4349                                                 return "Query \"{$cmd}\" failed with error code \"$err\".\n";
4350                                         }
4351                                 }
4352                                 $cmd = '';
4353                         }
4354                 }
4355
4356                 ScopedCallback::consume( $delimiterReset );
4357                 return true;
4358         }
4359
4360         /**
4361          * Called by sourceStream() to check if we've reached a statement end
4362          *
4363          * @param string &$sql SQL assembled so far
4364          * @param string &$newLine New line about to be added to $sql
4365          * @return bool Whether $newLine contains end of the statement
4366          */
4367         public function streamStatementEnd( &$sql, &$newLine ) {
4368                 if ( $this->delimiter ) {
4369                         $prev = $newLine;
4370                         $newLine = preg_replace(
4371                                 '/' . preg_quote( $this->delimiter, '/' ) . '$/', '', $newLine );
4372                         if ( $newLine != $prev ) {
4373                                 return true;
4374                         }
4375                 }
4376
4377                 return false;
4378         }
4379
4380         /**
4381          * Database independent variable replacement. Replaces a set of variables
4382          * in an SQL statement with their contents as given by $this->getSchemaVars().
4383          *
4384          * Supports '{$var}' `{$var}` and / *$var* / (without the spaces) style variables.
4385          *
4386          * - '{$var}' should be used for text and is passed through the database's
4387          *   addQuotes method.
4388          * - `{$var}` should be used for identifiers (e.g. table and database names).
4389          *   It is passed through the database's addIdentifierQuotes method which
4390          *   can be overridden if the database uses something other than backticks.
4391          * - / *_* / or / *$wgDBprefix* / passes the name that follows through the
4392          *   database's tableName method.
4393          * - / *i* / passes the name that follows through the database's indexName method.
4394          * - In all other cases, / *$var* / is left unencoded. Except for table options,
4395          *   its use should be avoided. In 1.24 and older, string encoding was applied.
4396          *
4397          * @param string $ins SQL statement to replace variables in
4398          * @return string The new SQL statement with variables replaced
4399          */
4400         protected function replaceVars( $ins ) {
4401                 $vars = $this->getSchemaVars();
4402                 return preg_replace_callback(
4403                         '!
4404                                 /\* (\$wgDBprefix|[_i]) \*/ (\w*) | # 1-2. tableName, indexName
4405                                 \'\{\$ (\w+) }\'                  | # 3. addQuotes
4406                                 `\{\$ (\w+) }`                    | # 4. addIdentifierQuotes
4407                                 /\*\$ (\w+) \*/                     # 5. leave unencoded
4408                         !x',
4409                         function ( $m ) use ( $vars ) {
4410                                 // Note: Because of <https://bugs.php.net/bug.php?id=51881>,
4411                                 // check for both nonexistent keys *and* the empty string.
4412                                 if ( isset( $m[1] ) && $m[1] !== '' ) {
4413                                         if ( $m[1] === 'i' ) {
4414                                                 return $this->indexName( $m[2] );
4415                                         } else {
4416                                                 return $this->tableName( $m[2] );
4417                                         }
4418                                 } elseif ( isset( $m[3] ) && $m[3] !== '' && array_key_exists( $m[3], $vars ) ) {
4419                                         return $this->addQuotes( $vars[$m[3]] );
4420                                 } elseif ( isset( $m[4] ) && $m[4] !== '' && array_key_exists( $m[4], $vars ) ) {
4421                                         return $this->addIdentifierQuotes( $vars[$m[4]] );
4422                                 } elseif ( isset( $m[5] ) && $m[5] !== '' && array_key_exists( $m[5], $vars ) ) {
4423                                         return $vars[$m[5]];
4424                                 } else {
4425                                         return $m[0];
4426                                 }
4427                         },
4428                         $ins
4429                 );
4430         }
4431
4432         /**
4433          * Get schema variables. If none have been set via setSchemaVars(), then
4434          * use some defaults from the current object.
4435          *
4436          * @return array
4437          */
4438         protected function getSchemaVars() {
4439                 if ( $this->schemaVars ) {
4440                         return $this->schemaVars;
4441                 } else {
4442                         return $this->getDefaultSchemaVars();
4443                 }
4444         }
4445
4446         /**
4447          * Get schema variables to use if none have been set via setSchemaVars().
4448          *
4449          * Override this in derived classes to provide variables for tables.sql
4450          * and SQL patch files.
4451          *
4452          * @return array
4453          */
4454         protected function getDefaultSchemaVars() {
4455                 return [];
4456         }
4457
4458         public function lockIsFree( $lockName, $method ) {
4459                 // RDBMs methods for checking named locks may or may not count this thread itself.
4460                 // In MySQL, IS_FREE_LOCK() returns 0 if the thread already has the lock. This is
4461                 // the behavior choosen by the interface for this method.
4462                 return !isset( $this->namedLocksHeld[$lockName] );
4463         }
4464
4465         public function lock( $lockName, $method, $timeout = 5 ) {
4466                 $this->namedLocksHeld[$lockName] = 1;
4467
4468                 return true;
4469         }
4470
4471         public function unlock( $lockName, $method ) {
4472                 unset( $this->namedLocksHeld[$lockName] );
4473
4474                 return true;
4475         }
4476
4477         public function getScopedLockAndFlush( $lockKey, $fname, $timeout ) {
4478                 if ( $this->writesOrCallbacksPending() ) {
4479                         // This only flushes transactions to clear snapshots, not to write data
4480                         $fnames = implode( ', ', $this->pendingWriteAndCallbackCallers() );
4481                         throw new DBUnexpectedError(
4482                                 $this,
4483                                 "$fname: Cannot flush pre-lock snapshot because writes are pending ($fnames)."
4484                         );
4485                 }
4486
4487                 if ( !$this->lock( $lockKey, $fname, $timeout ) ) {
4488                         return null;
4489                 }
4490
4491                 $unlocker = new ScopedCallback( function () use ( $lockKey, $fname ) {
4492                         if ( $this->trxLevel() ) {
4493                                 // There is a good chance an exception was thrown, causing any early return
4494                                 // from the caller. Let any error handler get a chance to issue rollback().
4495                                 // If there isn't one, let the error bubble up and trigger server-side rollback.
4496                                 $this->onTransactionResolution(
4497                                         function () use ( $lockKey, $fname ) {
4498                                                 $this->unlock( $lockKey, $fname );
4499                                         },
4500                                         $fname
4501                                 );
4502                         } else {
4503                                 $this->unlock( $lockKey, $fname );
4504                         }
4505                 } );
4506
4507                 $this->commit( $fname, self::FLUSHING_INTERNAL );
4508
4509                 return $unlocker;
4510         }
4511
4512         public function namedLocksEnqueue() {
4513                 return false;
4514         }
4515
4516         public function tableLocksHaveTransactionScope() {
4517                 return true;
4518         }
4519
4520         final public function lockTables( array $read, array $write, $method ) {
4521                 if ( $this->writesOrCallbacksPending() ) {
4522                         throw new DBUnexpectedError( $this, "Transaction writes or callbacks still pending." );
4523                 }
4524
4525                 if ( $this->tableLocksHaveTransactionScope() ) {
4526                         $this->startAtomic( $method );
4527                 }
4528
4529                 return $this->doLockTables( $read, $write, $method );
4530         }
4531
4532         /**
4533          * Helper function for lockTables() that handles the actual table locking
4534          *
4535          * @param array $read Array of tables to lock for read access
4536          * @param array $write Array of tables to lock for write access
4537          * @param string $method Name of caller
4538          * @return true
4539          */
4540         protected function doLockTables( array $read, array $write, $method ) {
4541                 return true;
4542         }
4543
4544         final public function unlockTables( $method ) {
4545                 if ( $this->tableLocksHaveTransactionScope() ) {
4546                         $this->endAtomic( $method );
4547
4548                         return true; // locks released on COMMIT/ROLLBACK
4549                 }
4550
4551                 return $this->doUnlockTables( $method );
4552         }
4553
4554         /**
4555          * Helper function for unlockTables() that handles the actual table unlocking
4556          *
4557          * @param string $method Name of caller
4558          * @return true
4559          */
4560         protected function doUnlockTables( $method ) {
4561                 return true;
4562         }
4563
4564         /**
4565          * Delete a table
4566          * @param string $tableName
4567          * @param string $fName
4568          * @return bool|ResultWrapper
4569          * @since 1.18
4570          */
4571         public function dropTable( $tableName, $fName = __METHOD__ ) {
4572                 if ( !$this->tableExists( $tableName, $fName ) ) {
4573                         return false;
4574                 }
4575                 $sql = "DROP TABLE " . $this->tableName( $tableName ) . " CASCADE";
4576
4577                 return $this->query( $sql, $fName );
4578         }
4579
4580         public function getInfinity() {
4581                 return 'infinity';
4582         }
4583
4584         public function encodeExpiry( $expiry ) {
4585                 return ( $expiry == '' || $expiry == 'infinity' || $expiry == $this->getInfinity() )
4586                         ? $this->getInfinity()
4587                         : $this->timestamp( $expiry );
4588         }
4589
4590         public function decodeExpiry( $expiry, $format = TS_MW ) {
4591                 if ( $expiry == '' || $expiry == 'infinity' || $expiry == $this->getInfinity() ) {
4592                         return 'infinity';
4593                 }
4594
4595                 return ConvertibleTimestamp::convert( $format, $expiry );
4596         }
4597
4598         public function setBigSelects( $value = true ) {
4599                 // no-op
4600         }
4601
4602         public function isReadOnly() {
4603                 return ( $this->getReadOnlyReason() !== false );
4604         }
4605
4606         /**
4607          * @return string|bool Reason this DB is read-only or false if it is not
4608          */
4609         protected function getReadOnlyReason() {
4610                 $reason = $this->getLBInfo( 'readOnlyReason' );
4611
4612                 return is_string( $reason ) ? $reason : false;
4613         }
4614
4615         public function setTableAliases( array $aliases ) {
4616                 $this->tableAliases = $aliases;
4617         }
4618
4619         public function setIndexAliases( array $aliases ) {
4620                 $this->indexAliases = $aliases;
4621         }
4622
4623         /**
4624          * Get the underlying binding connection handle
4625          *
4626          * Makes sure the connection resource is set (disconnects and ping() failure can unset it).
4627          * This catches broken callers than catch and ignore disconnection exceptions.
4628          * Unlike checking isOpen(), this is safe to call inside of open().
4629          *
4630          * @return mixed
4631          * @throws DBUnexpectedError
4632          * @since 1.26
4633          */
4634         protected function getBindingHandle() {
4635                 if ( !$this->conn ) {
4636                         throw new DBUnexpectedError(
4637                                 $this,
4638                                 'DB connection was already closed or the connection dropped.'
4639                         );
4640                 }
4641
4642                 return $this->conn;
4643         }
4644
4645         /**
4646          * @since 1.19
4647          * @return string
4648          */
4649         public function __toString() {
4650                 return (string)$this->conn;
4651         }
4652
4653         /**
4654          * Make sure that copies do not share the same client binding handle
4655          * @throws DBConnectionError
4656          */
4657         public function __clone() {
4658                 $this->connLogger->warning(
4659                         "Cloning " . static::class . " is not recommended; forking connection:\n" .
4660                         ( new RuntimeException() )->getTraceAsString()
4661                 );
4662
4663                 if ( $this->isOpen() ) {
4664                         // Open a new connection resource without messing with the old one
4665                         $this->opened = false;
4666                         $this->conn = false;
4667                         $this->trxEndCallbacks = []; // don't copy
4668                         $this->handleSessionLoss(); // no trx or locks anymore
4669                         $this->open(
4670                                 $this->server,
4671                                 $this->user,
4672                                 $this->password,
4673                                 $this->getDBname(),
4674                                 $this->dbSchema(),
4675                                 $this->tablePrefix()
4676                         );
4677                         $this->lastPing = microtime( true );
4678                 }
4679         }
4680
4681         /**
4682          * Called by serialize. Throw an exception when DB connection is serialized.
4683          * This causes problems on some database engines because the connection is
4684          * not restored on unserialize.
4685          */
4686         public function __sleep() {
4687                 throw new RuntimeException( 'Database serialization may cause problems, since ' .
4688                         'the connection is not restored on wakeup.' );
4689         }
4690
4691         /**
4692          * Run a few simple sanity checks and close dangling connections
4693          */
4694         public function __destruct() {
4695                 if ( $this->trxLevel && $this->trxDoneWrites ) {
4696                         trigger_error( "Uncommitted DB writes (transaction from {$this->trxFname})." );
4697                 }
4698
4699                 $danglingWriters = $this->pendingWriteAndCallbackCallers();
4700                 if ( $danglingWriters ) {
4701                         $fnames = implode( ', ', $danglingWriters );
4702                         trigger_error( "DB transaction writes or callbacks still pending ($fnames)." );
4703                 }
4704
4705                 if ( $this->conn ) {
4706                         // Avoid connection leaks for sanity. Normally, resources close at script completion.
4707                         // The connection might already be closed in zend/hhvm by now, so suppress warnings.
4708                         Wikimedia\suppressWarnings();
4709                         $this->closeConnection();
4710                         Wikimedia\restoreWarnings();
4711                         $this->conn = false;
4712                         $this->opened = false;
4713                 }
4714         }
4715 }
4716
4717 /**
4718  * @deprecated since 1.28
4719  */
4720 class_alias( Database::class, 'DatabaseBase' );
4721
4722 /**
4723  * @deprecated since 1.29
4724  */
4725 class_alias( Database::class, 'Database' );