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 callable Error logging callback */
 101         protected $errorLogger;
 102         /** @var callable 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                                 return $this->pingAndCalculateLastTrxApplyTime();
 723                         default: // everything
 724                                 return $this->trxWriteDuration;
 725                 }
 726         }
 727
 728         /**
 729          * @return float Time to apply writes to replicas based on trxWrite* fields
 730          */
 731         private function pingAndCalculateLastTrxApplyTime() {
 732                 $this->ping( $rtt );
 733
 734                 $rttAdjTotal = $this->trxWriteAdjQueryCount * $rtt;
 735                 $applyTime = max( $this->trxWriteAdjDuration - $rttAdjTotal, 0 );
 736                 // For omitted queries, make them count as something at least
 737                 $omitted = $this->trxWriteQueryCount - $this->trxWriteAdjQueryCount;
 738                 $applyTime += self::TINY_WRITE_SEC * $omitted;
 739
 740                 return $applyTime;
 741         }
 742
 743         public function pendingWriteCallers() {
 744                 return $this->trxLevel ? $this->trxWriteCallers : [];
 745         }
 746
 747         public function pendingWriteRowsAffected() {
 748                 return $this->trxWriteAffectedRows;
 749         }
 750
 751         /**
 752          * List the methods that have write queries or callbacks for the current transaction
 753          *
 754          * This method should not be used outside of Database/LoadBalancer
 755          *
 756          * @return string[]
 757          * @since 1.32
 758          */
 759         public function pendingWriteAndCallbackCallers() {
 760                 $fnames = $this->pendingWriteCallers();
 761                 foreach ( [
 762                         $this->trxIdleCallbacks,
 763                         $this->trxPreCommitCallbacks,
 764                         $this->trxEndCallbacks
 765                 ] as $callbacks ) {
 766                         foreach ( $callbacks as $callback ) {
 767                                 $fnames[] = $callback[1];
 768                         }
 769                 }
 770
 771                 return $fnames;
 772         }
 773
 774         /**
 775          * @return string
 776          */
 777         private function flatAtomicSectionList() {
 778                 return array_reduce( $this->trxAtomicLevels, function ( $accum, $v ) {
 779                         return $accum === null ? $v[0] : "$accum, " . $v[0];
 780                 } );
 781         }
 782
 783         public function isOpen() {
 784                 return $this->opened;
 785         }
 786
 787         public function setFlag( $flag, $remember = self::REMEMBER_NOTHING ) {
 788                 if ( ( $flag & self::DBO_IGNORE ) ) {
 789                         throw new UnexpectedValueException( "Modifying DBO_IGNORE is not allowed." );
 790                 }
 791
 792                 if ( $remember === self::REMEMBER_PRIOR ) {
 793                         array_push( $this->priorFlags, $this->flags );
 794                 }
 795                 $this->flags |= $flag;
 796         }
 797
 798         public function clearFlag( $flag, $remember = self::REMEMBER_NOTHING ) {
 799                 if ( ( $flag & self::DBO_IGNORE ) ) {
 800                         throw new UnexpectedValueException( "Modifying DBO_IGNORE is not allowed." );
 801                 }
 802
 803                 if ( $remember === self::REMEMBER_PRIOR ) {
 804                         array_push( $this->priorFlags, $this->flags );
 805                 }
 806                 $this->flags &= ~$flag;
 807         }
 808
 809         public function restoreFlags( $state = self::RESTORE_PRIOR ) {
 810                 if ( !$this->priorFlags ) {
 811                         return;
 812                 }
 813
 814                 if ( $state === self::RESTORE_INITIAL ) {
 815                         $this->flags = reset( $this->priorFlags );
 816                         $this->priorFlags = [];
 817                 } else {
 818                         $this->flags = array_pop( $this->priorFlags );
 819                 }
 820         }
 821
 822         public function getFlag( $flag ) {
 823                 return !!( $this->flags & $flag );
 824         }
 825
 826         /**
 827          * @param string $name Class field name
 828          * @return mixed
 829          * @deprecated Since 1.28
 830          */
 831         public function getProperty( $name ) {
 832                 return $this->$name;
 833         }
 834
 835         public function getDomainID() {
 836                 return $this->currentDomain->getId();
 837         }
 838
 839         final public function getWikiID() {
 840                 return $this->getDomainID();
 841         }
 842
 843         /**
 844          * Get information about an index into an object
 845          * @param string $table Table name
 846          * @param string $index Index name
 847          * @param string $fname Calling function name
 848          * @return mixed Database-specific index description class or false if the index does not exist
 849          */
 850         abstract function indexInfo( $table, $index, $fname = __METHOD__ );
 851
 852         /**
 853          * Wrapper for addslashes()
 854          *
 855          * @param string $s String to be slashed.
 856          * @return string Slashed string.
 857          */
 858         abstract function strencode( $s );
 859
 860         /**
 861          * Set a custom error handler for logging errors during database connection
 862          */
 863         protected function installErrorHandler() {
 864                 $this->phpError = false;
 865                 $this->htmlErrors = ini_set( 'html_errors', '0' );
 866                 set_error_handler( [ $this, 'connectionErrorLogger' ] );
 867         }
 868
 869         /**
 870          * Restore the previous error handler and return the last PHP error for this DB
 871          *
 872          * @return bool|string
 873          */
 874         protected function restoreErrorHandler() {
 875                 restore_error_handler();
 876                 if ( $this->htmlErrors !== false ) {
 877                         ini_set( 'html_errors', $this->htmlErrors );
 878                 }
 879
 880                 return $this->getLastPHPError();
 881         }
 882
 883         /**
 884          * @return string|bool Last PHP error for this DB (typically connection errors)
 885          */
 886         protected function getLastPHPError() {
 887                 if ( $this->phpError ) {
 888                         $error = preg_replace( '!\[<a.*</a>\]!', '', $this->phpError );
 889                         $error = preg_replace( '!^.*?:\s?(.*)$!', '$1', $error );
 890
 891                         return $error;
 892                 }
 893
 894                 return false;
 895         }
 896
 897         /**
 898          * Error handler for logging errors during database connection
 899          * This method should not be used outside of Database classes
 900          *
 901          * @param int $errno
 902          * @param string $errstr
 903          */
 904         public function connectionErrorLogger( $errno, $errstr ) {
 905                 $this->phpError = $errstr;
 906         }
 907
 908         /**
 909          * Create a log context to pass to PSR-3 logger functions.
 910          *
 911          * @param array $extras Additional data to add to context
 912          * @return array
 913          */
 914         protected function getLogContext( array $extras = [] ) {
 915                 return array_merge(
 916                         [
 917                                 'db_server' => $this->server,
 918                                 'db_name' => $this->getDBname(),
 919                                 'db_user' => $this->user,
 920                         ],
 921                         $extras
 922                 );
 923         }
 924
 925         final public function close() {
 926                 $exception = null; // error to throw after disconnecting
 927
 928                 if ( $this->conn ) {
 929                         // Roll back any dangling transaction first
 930                         if ( $this->trxLevel ) {
 931                                 if ( $this->trxAtomicLevels ) {
 932                                         // Cannot let incomplete atomic sections be committed
 933                                         $levels = $this->flatAtomicSectionList();
 934                                         $exception = new DBUnexpectedError(
 935                                                 $this,
 936                                                 __METHOD__ . ": atomic sections $levels are still open."
 937                                         );
 938                                 } elseif ( $this->trxAutomatic ) {
 939                                         // Only the connection manager can commit non-empty DBO_TRX transactions
 940                                         // (empty ones we can silently roll back)
 941                                         if ( $this->writesOrCallbacksPending() ) {
 942                                                 $exception = new DBUnexpectedError(
 943                                                         $this,
 944                                                         __METHOD__ .
 945                                                         ": mass commit/rollback of peer transaction required (DBO_TRX set)."
 946                                                 );
 947                                         }
 948                                 } else {
 949                                         // Manual transactions should have been committed or rolled
 950                                         // back, even if empty.
 951                                         $exception = new DBUnexpectedError(
 952                                                 $this,
 953                                                 __METHOD__ . ": transaction is still open (from {$this->trxFname})."
 954                                         );
 955                                 }
 956
 957                                 if ( $this->trxEndCallbacksSuppressed ) {
 958                                         $exception = $exception ?: new DBUnexpectedError(
 959                                                 $this,
 960                                                 __METHOD__ . ': callbacks are suppressed; cannot properly commit.'
 961                                         );
 962                                 }
 963
 964                                 // Rollback the changes and run any callbacks as needed
 965                                 $this->rollback( __METHOD__, self::FLUSHING_INTERNAL );
 966                         }
 967
 968                         // Close the actual connection in the binding handle
 969                         $closed = $this->closeConnection();
 970                         $this->conn = false;
 971                 } else {
 972                         $closed = true; // already closed; nothing to do
 973                 }
 974
 975                 $this->opened = false;
 976
 977                 // Throw any unexpected errors after having disconnected
 978                 if ( $exception instanceof Exception ) {
 979                         throw $exception;
 980                 }
 981
 982                 // Sanity check that no callbacks are dangling
 983                 $fnames = $this->pendingWriteAndCallbackCallers();
 984                 if ( $fnames ) {
 985                         throw new RuntimeException(
 986                                 "Transaction callbacks are still pending:\n" . implode( ', ', $fnames )
 987                         );
 988                 }
 989
 990                 return $closed;
 991         }
 992
 993         /**
 994          * Make sure isOpen() returns true as a sanity check
 995          *
 996          * @throws DBUnexpectedError
 997          */
 998         protected function assertOpen() {
 999                 if ( !$this->isOpen() ) {
1000                         throw new DBUnexpectedError( $this, "DB connection was already closed." );
1001                 }
1002         }
1003
1004         /**
1005          * Closes underlying database connection
1006          * @since 1.20
1007          * @return bool Whether connection was closed successfully
1008          */
1009         abstract protected function closeConnection();
1010
1011         /**
1012          * @deprecated since 1.32
1013          * @param string $error Fallback message, if none is given by DB
1014          * @throws DBConnectionError
1015          */
1016         public function reportConnectionError( $error = 'Unknown error' ) {
1017                 call_user_func( $this->deprecationLogger, 'Use of ' . __METHOD__ . ' is deprecated.' );
1018                 throw new DBConnectionError( $this, $this->lastError() ?: $error );
1019         }
1020
1021         /**
1022          * Run a query and return a DBMS-dependent wrapper (that has all IResultWrapper methods)
1023          *
1024          * This might return things, such as mysqli_result, that do not formally implement
1025          * IResultWrapper, but nonetheless implement all of its methods correctly
1026          *
1027          * @param string $sql SQL query.
1028          * @return IResultWrapper|bool Iterator to feed to fetchObject/fetchRow; false on failure
1029          */
1030         abstract protected function doQuery( $sql );
1031
1032         /**
1033          * Determine whether a query writes to the DB. When in doubt, this returns true.
1034          *
1035          * Main use cases:
1036          *
1037          * - Subsequent web requests should not need to wait for replication from
1038          *   the master position seen by this web request, unless this request made
1039          *   changes to the master. This is handled by ChronologyProtector by checking
1040          *   doneWrites() at the end of the request. doneWrites() returns true if any
1041          *   query set lastWriteTime; which query() does based on isWriteQuery().
1042          *
1043          * - Reject write queries to replica DBs, in query().
1044          *
1045          * @param string $sql
1046          * @return bool
1047          */
1048         protected function isWriteQuery( $sql ) {
1049                 // BEGIN and COMMIT queries are considered read queries here.
1050                 // Database backends and drivers (MySQL, MariaDB, php-mysqli) generally
1051                 // treat these as write queries, in that their results have "affected rows"
1052                 // as meta data as from writes, instead of "num rows" as from reads.
1053                 // But, we treat them as read queries because when reading data (from
1054                 // either replica or master) we use transactions to enable repeatable-read
1055                 // snapshots, which ensures we get consistent results from the same snapshot
1056                 // for all queries within a request. Use cases:
1057                 // - Treating these as writes would trigger ChronologyProtector (see method doc).
1058                 // - We use this method to reject writes to replicas, but we need to allow
1059                 //   use of transactions on replicas for read snapshots. This fine given
1060                 //   that transactions by themselves don't make changes, only actual writes
1061                 //   within the transaction matter, which we still detect.
1062                 return !preg_match(
1063                         '/^(?:SELECT|BEGIN|ROLLBACK|COMMIT|SAVEPOINT|RELEASE|SET|SHOW|EXPLAIN|\(SELECT)\b/i',
1064                         $sql
1065                 );
1066         }
1067
1068         /**
1069          * @param string $sql
1070          * @return string|null
1071          */
1072         protected function getQueryVerb( $sql ) {
1073                 return preg_match( '/^\s*([a-z]+)/i', $sql, $m ) ? strtoupper( $m[1] ) : null;
1074         }
1075
1076         /**
1077          * Determine whether a SQL statement is sensitive to isolation level.
1078          *
1079          * A SQL statement is considered transactable if its result could vary
1080          * depending on the transaction isolation level. Operational commands
1081          * such as 'SET' and 'SHOW' are not considered to be transactable.
1082          *
1083          * Main purpose: Used by query() to decide whether to begin a transaction
1084          * before the current query (in DBO_TRX mode, on by default).
1085          *
1086          * @param string $sql
1087          * @return bool
1088          */
1089         protected function isTransactableQuery( $sql ) {
1090                 return !in_array(
1091                         $this->getQueryVerb( $sql ),
1092                         [ 'BEGIN', 'ROLLBACK', 'COMMIT', 'SET', 'SHOW', 'CREATE', 'ALTER' ],
1093                         true
1094                 );
1095         }
1096
1097         /**
1098          * @param string $sql A SQL query
1099          * @return bool Whether $sql is SQL for TEMPORARY table operation
1100          */
1101         protected function registerTempTableOperation( $sql ) {
1102                 if ( preg_match(
1103                         '/^CREATE\s+TEMPORARY\s+TABLE\s+(?:IF\s+NOT\s+EXISTS\s+)?[`"\']?(\w+)[`"\']?/i',
1104                         $sql,
1105                         $matches
1106                 ) ) {
1107                         $this->sessionTempTables[$matches[1]] = 1;
1108
1109                         return true;
1110                 } elseif ( preg_match(
1111                         '/^DROP\s+(?:TEMPORARY\s+)?TABLE\s+(?:IF\s+EXISTS\s+)?[`"\']?(\w+)[`"\']?/i',
1112                         $sql,
1113                         $matches
1114                 ) ) {
1115                         $isTemp = isset( $this->sessionTempTables[$matches[1]] );
1116                         unset( $this->sessionTempTables[$matches[1]] );
1117
1118                         return $isTemp;
1119                 } elseif ( preg_match(
1120                         '/^TRUNCATE\s+(?:TEMPORARY\s+)?TABLE\s+(?:IF\s+EXISTS\s+)?[`"\']?(\w+)[`"\']?/i',
1121                         $sql,
1122                         $matches
1123                 ) ) {
1124                         return isset( $this->sessionTempTables[$matches[1]] );
1125                 } elseif ( preg_match(
1126                         '/^(?:INSERT\s+(?:\w+\s+)?INTO|UPDATE|DELETE\s+FROM)\s+[`"\']?(\w+)[`"\']?/i',
1127                         $sql,
1128                         $matches
1129                 ) ) {
1130                         return isset( $this->sessionTempTables[$matches[1]] );
1131                 }
1132
1133                 return false;
1134         }
1135
1136         public function query( $sql, $fname = __METHOD__, $tempIgnore = false ) {
1137                 $this->assertTransactionStatus( $sql, $fname );
1138
1139                 # Avoid fatals if close() was called
1140                 $this->assertOpen();
1141
1142                 $priorWritesPending = $this->writesOrCallbacksPending();
1143                 $this->lastQuery = $sql;
1144
1145                 $isWrite = $this->isWriteQuery( $sql );
1146                 if ( $isWrite ) {
1147                         $isNonTempWrite = !$this->registerTempTableOperation( $sql );
1148                 } else {
1149                         $isNonTempWrite = false;
1150                 }
1151
1152                 if ( $isWrite ) {
1153                         if ( $this->getLBInfo( 'replica' ) === true ) {
1154                                 throw new DBError(
1155                                         $this,
1156                                         'Write operations are not allowed on replica database connections.'
1157                                 );
1158                         }
1159                         # In theory, non-persistent writes are allowed in read-only mode, but due to things
1160                         # like https://bugs.mysql.com/bug.php?id=33669 that might not work anyway...
1161                         $reason = $this->getReadOnlyReason();
1162                         if ( $reason !== false ) {
1163                                 throw new DBReadOnlyError( $this, "Database is read-only: $reason" );
1164                         }
1165                         # Set a flag indicating that writes have been done
1166                         $this->lastWriteTime = microtime( true );
1167                 }
1168
1169                 # Add trace comment to the begin of the sql string, right after the operator.
1170                 # Or, for one-word queries (like "BEGIN" or COMMIT") add it to the end (T44598)
1171                 $commentedSql = preg_replace( '/\s|$/', " /* $fname {$this->agent} */ ", $sql, 1 );
1172
1173                 # Start implicit transactions that wrap the request if DBO_TRX is enabled
1174                 if ( !$this->trxLevel && $this->getFlag( self::DBO_TRX )
1175                         && $this->isTransactableQuery( $sql )
1176                 ) {
1177                         $this->begin( __METHOD__ . " ($fname)", self::TRANSACTION_INTERNAL );
1178                         $this->trxAutomatic = true;
1179                 }
1180
1181                 # Keep track of whether the transaction has write queries pending
1182                 if ( $this->trxLevel && !$this->trxDoneWrites && $isWrite ) {
1183                         $this->trxDoneWrites = true;
1184                         $this->trxProfiler->transactionWritingIn(
1185                                 $this->server, $this->getDomainID(), $this->trxShortId );
1186                 }
1187
1188                 if ( $this->getFlag( self::DBO_DEBUG ) ) {
1189                         $this->queryLogger->debug( "{$this->getDomainID()} {$commentedSql}" );
1190                 }
1191
1192                 # Send the query to the server and fetch any corresponding errors
1193                 $ret = $this->doProfiledQuery( $sql, $commentedSql, $isNonTempWrite, $fname );
1194                 $lastError = $this->lastError();
1195                 $lastErrno = $this->lastErrno();
1196
1197                 # Try reconnecting if the connection was lost
1198                 if ( $ret === false && $this->wasConnectionLoss() ) {
1199                         # Check if any meaningful session state was lost
1200                         $recoverable = $this->canRecoverFromDisconnect( $sql, $priorWritesPending );
1201                         # Update session state tracking and try to restore the connection
1202                         $reconnected = $this->replaceLostConnection( __METHOD__ );
1203                         # Silently resend the query to the server if it is safe and possible
1204                         if ( $reconnected && $recoverable ) {
1205                                 $ret = $this->doProfiledQuery( $sql, $commentedSql, $isNonTempWrite, $fname );
1206                                 $lastError = $this->lastError();
1207                                 $lastErrno = $this->lastErrno();
1208
1209                                 if ( $ret === false && $this->wasConnectionLoss() ) {
1210                                         # Query probably causes disconnects; reconnect and do not re-run it
1211                                         $this->replaceLostConnection( __METHOD__ );
1212                                 }
1213                         }
1214                 }
1215
1216                 if ( $ret === false ) {
1217                         if ( $this->trxLevel ) {
1218                                 if ( $this->wasKnownStatementRollbackError() ) {
1219                                         # We're ignoring an error that caused just the current query to be aborted.
1220                                         # But log the cause so we can log a deprecation notice if a caller actually
1221                                         # does ignore it.
1222                                         $this->trxStatusIgnoredCause = [ $lastError, $lastErrno, $fname ];
1223                                 } else {
1224                                         # Either the query was aborted or all queries after BEGIN where aborted.
1225                                         # In the first case, the only options going forward are (a) ROLLBACK, or
1226                                         # (b) ROLLBACK TO SAVEPOINT (if one was set). If the later case, the only
1227                                         # option is ROLLBACK, since the snapshots would have been released.
1228                                         $this->trxStatus = self::STATUS_TRX_ERROR;
1229                                         $this->trxStatusCause =
1230                                                 $this->makeQueryException( $lastError, $lastErrno, $sql, $fname );
1231                                         $tempIgnore = false; // cannot recover
1232                                         $this->trxStatusIgnoredCause = null;
1233                                 }
1234                         }
1235
1236                         $this->reportQueryError( $lastError, $lastErrno, $sql, $fname, $tempIgnore );
1237                 }
1238
1239                 return $this->resultObject( $ret );
1240         }
1241
1242         /**
1243          * Wrapper for query() that also handles profiling, logging, and affected row count updates
1244          *
1245          * @param string $sql Original SQL query
1246          * @param string $commentedSql SQL query with debugging/trace comment
1247          * @param bool $isWrite Whether the query is a (non-temporary) write operation
1248          * @param string $fname Name of the calling function
1249          * @return bool|ResultWrapper True for a successful write query, ResultWrapper
1250          *     object for a successful read query, or false on failure
1251          */
1252         private function doProfiledQuery( $sql, $commentedSql, $isWrite, $fname ) {
1253                 $isMaster = !is_null( $this->getLBInfo( 'master' ) );
1254                 # generalizeSQL() will probably cut down the query to reasonable
1255                 # logging size most of the time. The substr is really just a sanity check.
1256                 if ( $isMaster ) {
1257                         $queryProf = 'query-m: ' . substr( self::generalizeSQL( $sql ), 0, 255 );
1258                 } else {
1259                         $queryProf = 'query: ' . substr( self::generalizeSQL( $sql ), 0, 255 );
1260                 }
1261
1262                 # Include query transaction state
1263                 $queryProf .= $this->trxShortId ? " [TRX#{$this->trxShortId}]" : "";
1264
1265                 $startTime = microtime( true );
1266                 if ( $this->profiler ) {
1267                         $this->profiler->profileIn( $queryProf );
1268                 }
1269                 $this->affectedRowCount = null;
1270                 $ret = $this->doQuery( $commentedSql );
1271                 $this->affectedRowCount = $this->affectedRows();
1272                 if ( $this->profiler ) {
1273                         $this->profiler->profileOut( $queryProf );
1274                 }
1275                 $queryRuntime = max( microtime( true ) - $startTime, 0.0 );
1276
1277                 unset( $queryProfSection ); // profile out (if set)
1278
1279                 if ( $ret !== false ) {
1280                         $this->lastPing = $startTime;
1281                         if ( $isWrite && $this->trxLevel ) {
1282                                 $this->updateTrxWriteQueryTime( $sql, $queryRuntime, $this->affectedRows() );
1283                                 $this->trxWriteCallers[] = $fname;
1284                         }
1285                 }
1286
1287                 if ( $sql === self::PING_QUERY ) {
1288                         $this->rttEstimate = $queryRuntime;
1289                 }
1290
1291                 $this->trxProfiler->recordQueryCompletion(
1292                         $queryProf,
1293                         $startTime,
1294                         $isWrite,
1295                         $isWrite ? $this->affectedRows() : $this->numRows( $ret )
1296                 );
1297                 $this->queryLogger->debug( $sql, [
1298                         'method' => $fname,
1299                         'master' => $isMaster,
1300                         'runtime' => $queryRuntime,
1301                 ] );
1302
1303                 return $ret;
1304         }
1305
1306         /**
1307          * Update the estimated run-time of a query, not counting large row lock times
1308          *
1309          * LoadBalancer can be set to rollback transactions that will create huge replication
1310          * lag. It bases this estimate off of pendingWriteQueryDuration(). Certain simple
1311          * queries, like inserting a row can take a long time due to row locking. This method
1312          * uses some simple heuristics to discount those cases.
1313          *
1314          * @param string $sql A SQL write query
1315          * @param float $runtime Total runtime, including RTT
1316          * @param int $affected Affected row count
1317          */
1318         private function updateTrxWriteQueryTime( $sql, $runtime, $affected ) {
1319                 // Whether this is indicative of replica DB runtime (except for RBR or ws_repl)
1320                 $indicativeOfReplicaRuntime = true;
1321                 if ( $runtime > self::SLOW_WRITE_SEC ) {
1322                         $verb = $this->getQueryVerb( $sql );
1323                         // insert(), upsert(), replace() are fast unless bulky in size or blocked on locks
1324                         if ( $verb === 'INSERT' ) {
1325                                 $indicativeOfReplicaRuntime = $this->affectedRows() > self::SMALL_WRITE_ROWS;
1326                         } elseif ( $verb === 'REPLACE' ) {
1327                                 $indicativeOfReplicaRuntime = $this->affectedRows() > self::SMALL_WRITE_ROWS / 2;
1328                         }
1329                 }
1330
1331                 $this->trxWriteDuration += $runtime;
1332                 $this->trxWriteQueryCount += 1;
1333                 $this->trxWriteAffectedRows += $affected;
1334                 if ( $indicativeOfReplicaRuntime ) {
1335                         $this->trxWriteAdjDuration += $runtime;
1336                         $this->trxWriteAdjQueryCount += 1;
1337                 }
1338         }
1339
1340         /**
1341          * @param string $sql
1342          * @param string $fname
1343          * @throws DBTransactionStateError
1344          */
1345         private function assertTransactionStatus( $sql, $fname ) {
1346                 if ( $this->getQueryVerb( $sql ) === 'ROLLBACK' ) { // transaction/savepoint
1347                         return;
1348                 }
1349
1350                 if ( $this->trxStatus < self::STATUS_TRX_OK ) {
1351                         throw new DBTransactionStateError(
1352                                 $this,
1353                                 "Cannot execute query from $fname while transaction status is ERROR.",
1354                                 [],
1355                                 $this->trxStatusCause
1356                         );
1357                 } elseif ( $this->trxStatus === self::STATUS_TRX_OK && $this->trxStatusIgnoredCause ) {
1358                         list( $iLastError, $iLastErrno, $iFname ) = $this->trxStatusIgnoredCause;
1359                         call_user_func( $this->deprecationLogger,
1360                                 "Caller from $fname ignored an error originally raised from $iFname: " .
1361                                 "[$iLastErrno] $iLastError"
1362                         );
1363                         $this->trxStatusIgnoredCause = null;
1364                 }
1365         }
1366
1367         public function assertNoOpenTransactions() {
1368                 if ( $this->explicitTrxActive() ) {
1369                         throw new DBTransactionError(
1370                                 $this,
1371                                 "Explicit transaction still active. A caller may have caught an error. "
1372                                 . "Open transactions: " . $this->flatAtomicSectionList()
1373                         );
1374                 }
1375         }
1376
1377         /**
1378          * Determine whether or not it is safe to retry queries after a database
1379          * connection is lost
1380          *
1381          * @param string $sql SQL query
1382          * @param bool $priorWritesPending Whether there is a transaction open with
1383          *     possible write queries or transaction pre-commit/idle callbacks
1384          *     waiting on it to finish.
1385          * @return bool True if it is safe to retry the query, false otherwise
1386          */
1387         private function canRecoverFromDisconnect( $sql, $priorWritesPending ) {
1388                 # Transaction dropped; this can mean lost writes, or REPEATABLE-READ snapshots.
1389                 # Dropped connections also mean that named locks are automatically released.
1390                 # Only allow error suppression in autocommit mode or when the lost transaction
1391                 # didn't matter anyway (aside from DBO_TRX snapshot loss).
1392                 if ( $this->namedLocksHeld ) {
1393                         return false; // possible critical section violation
1394                 } elseif ( $this->sessionTempTables ) {
1395                         return false; // tables might be queried latter
1396                 } elseif ( $sql === 'COMMIT' ) {
1397                         return !$priorWritesPending; // nothing written anyway? (T127428)
1398                 } elseif ( $sql === 'ROLLBACK' ) {
1399                         return true; // transaction lost...which is also what was requested :)
1400                 } elseif ( $this->explicitTrxActive() ) {
1401                         return false; // don't drop atomocity and explicit snapshots
1402                 } elseif ( $priorWritesPending ) {
1403                         return false; // prior writes lost from implicit transaction
1404                 }
1405
1406                 return true;
1407         }
1408
1409         /**
1410          * Clean things up after session (and thus transaction) loss
1411          */
1412         private function handleSessionLoss() {
1413                 // Clean up tracking of session-level things...
1414                 // https://dev.mysql.com/doc/refman/5.7/en/implicit-commit.html
1415                 // https://www.postgresql.org/docs/9.2/static/sql-createtable.html (ignoring ON COMMIT)
1416                 $this->sessionTempTables = [];
1417                 // https://dev.mysql.com/doc/refman/5.7/en/miscellaneous-functions.html#function_get-lock
1418                 // https://www.postgresql.org/docs/9.4/static/functions-admin.html#FUNCTIONS-ADVISORY-LOCKS
1419                 $this->namedLocksHeld = [];
1420                 // Session loss implies transaction loss
1421                 $this->handleTransactionLoss();
1422         }
1423
1424         /**
1425          * Clean things up after transaction loss
1426          */
1427         private function handleTransactionLoss() {
1428                 $this->trxLevel = 0;
1429                 $this->trxAtomicCounter = 0;
1430                 $this->trxIdleCallbacks = []; // T67263; transaction already lost
1431                 $this->trxPreCommitCallbacks = []; // T67263; transaction already lost
1432                 try {
1433                         // Handle callbacks in trxEndCallbacks, e.g. onTransactionResolution().
1434                         // If callback suppression is set then the array will remain unhandled.
1435                         $this->runOnTransactionIdleCallbacks( self::TRIGGER_ROLLBACK );
1436                 } catch ( Exception $ex ) {
1437                         // Already logged; move on...
1438                 }
1439                 try {
1440                         // Handle callbacks in trxRecurringCallbacks, e.g. setTransactionListener()
1441                         $this->runTransactionListenerCallbacks( self::TRIGGER_ROLLBACK );
1442                 } catch ( Exception $ex ) {
1443                         // Already logged; move on...
1444                 }
1445         }
1446
1447         /**
1448          * Checks whether the cause of the error is detected to be a timeout.
1449          *
1450          * It returns false by default, and not all engines support detecting this yet.
1451          * If this returns false, it will be treated as a generic query error.
1452          *
1453          * @param string $error Error text
1454          * @param int $errno Error number
1455          * @return bool
1456          */
1457         protected function wasQueryTimeout( $error, $errno ) {
1458                 return false;
1459         }
1460
1461         /**
1462          * Report a query error. Log the error, and if neither the object ignore
1463          * flag nor the $tempIgnore flag is set, throw a DBQueryError.
1464          *
1465          * @param string $error
1466          * @param int $errno
1467          * @param string $sql
1468          * @param string $fname
1469          * @param bool $tempIgnore
1470          * @throws DBQueryError
1471          */
1472         public function reportQueryError( $error, $errno, $sql, $fname, $tempIgnore = false ) {
1473                 if ( $tempIgnore ) {
1474                         $this->queryLogger->debug( "SQL ERROR (ignored): $error\n" );
1475                 } else {
1476                         $exception = $this->makeQueryException( $error, $errno, $sql, $fname );
1477
1478                         throw $exception;
1479                 }
1480         }
1481
1482         /**
1483          * @param string $error
1484          * @param string|int $errno
1485          * @param string $sql
1486          * @param string $fname
1487          * @return DBError
1488          */
1489         private function makeQueryException( $error, $errno, $sql, $fname ) {
1490                 $sql1line = mb_substr( str_replace( "\n", "\\n", $sql ), 0, 5 * 1024 );
1491                 $this->queryLogger->error(
1492                         "{fname}\t{db_server}\t{errno}\t{error}\t{sql1line}",
1493                         $this->getLogContext( [
1494                                 'method' => __METHOD__,
1495                                 'errno' => $errno,
1496                                 'error' => $error,
1497                                 'sql1line' => $sql1line,
1498                                 'fname' => $fname,
1499                         ] )
1500                 );
1501                 $this->queryLogger->debug( "SQL ERROR: " . $error . "\n" );
1502                 $wasQueryTimeout = $this->wasQueryTimeout( $error, $errno );
1503                 if ( $wasQueryTimeout ) {
1504                         $e = new DBQueryTimeoutError( $this, $error, $errno, $sql, $fname );
1505                 } else {
1506                         $e = new DBQueryError( $this, $error, $errno, $sql, $fname );
1507                 }
1508
1509                 return $e;
1510         }
1511
1512         public function freeResult( $res ) {
1513         }
1514
1515         public function selectField(
1516                 $table, $var, $cond = '', $fname = __METHOD__, $options = [], $join_conds = []
1517         ) {
1518                 if ( $var === '*' ) { // sanity
1519                         throw new DBUnexpectedError( $this, "Cannot use a * field: got '$var'" );
1520                 }
1521
1522                 if ( !is_array( $options ) ) {
1523                         $options = [ $options ];
1524                 }
1525
1526                 $options['LIMIT'] = 1;
1527
1528                 $res = $this->select( $table, $var, $cond, $fname, $options, $join_conds );
1529                 if ( $res === false || !$this->numRows( $res ) ) {
1530                         return false;
1531                 }
1532
1533                 $row = $this->fetchRow( $res );
1534
1535                 if ( $row !== false ) {
1536                         return reset( $row );
1537                 } else {
1538                         return false;
1539                 }
1540         }
1541
1542         public function selectFieldValues(
1543                 $table, $var, $cond = '', $fname = __METHOD__, $options = [], $join_conds = []
1544         ) {
1545                 if ( $var === '*' ) { // sanity
1546                         throw new DBUnexpectedError( $this, "Cannot use a * field" );
1547                 } elseif ( !is_string( $var ) ) { // sanity
1548                         throw new DBUnexpectedError( $this, "Cannot use an array of fields" );
1549                 }
1550
1551                 if ( !is_array( $options ) ) {
1552                         $options = [ $options ];
1553                 }
1554
1555                 $res = $this->select( $table, [ 'value' => $var ], $cond, $fname, $options, $join_conds );
1556                 if ( $res === false ) {
1557                         return false;
1558                 }
1559
1560                 $values = [];
1561                 foreach ( $res as $row ) {
1562                         $values[] = $row->value;
1563                 }
1564
1565                 return $values;
1566         }
1567
1568         /**
1569          * Returns an optional USE INDEX clause to go after the table, and a
1570          * string to go at the end of the query.
1571          *
1572          * @param array $options Associative array of options to be turned into
1573          *   an SQL query, valid keys are listed in the function.
1574          * @return array
1575          * @see Database::select()
1576          */
1577         protected function makeSelectOptions( $options ) {
1578                 $preLimitTail = $postLimitTail = '';
1579                 $startOpts = '';
1580
1581                 $noKeyOptions = [];
1582
1583                 foreach ( $options as $key => $option ) {
1584                         if ( is_numeric( $key ) ) {
1585                                 $noKeyOptions[$option] = true;
1586                         }
1587                 }
1588
1589                 $preLimitTail .= $this->makeGroupByWithHaving( $options );
1590
1591                 $preLimitTail .= $this->makeOrderBy( $options );
1592
1593                 if ( isset( $noKeyOptions['FOR UPDATE'] ) ) {
1594                         $postLimitTail .= ' FOR UPDATE';
1595                 }
1596
1597                 if ( isset( $noKeyOptions['LOCK IN SHARE MODE'] ) ) {
1598                         $postLimitTail .= ' LOCK IN SHARE MODE';
1599                 }
1600
1601                 if ( isset( $noKeyOptions['DISTINCT'] ) || isset( $noKeyOptions['DISTINCTROW'] ) ) {
1602                         $startOpts .= 'DISTINCT';
1603                 }
1604
1605                 # Various MySQL extensions
1606                 if ( isset( $noKeyOptions['STRAIGHT_JOIN'] ) ) {
1607                         $startOpts .= ' /*! STRAIGHT_JOIN */';
1608                 }
1609
1610                 if ( isset( $noKeyOptions['HIGH_PRIORITY'] ) ) {
1611                         $startOpts .= ' HIGH_PRIORITY';
1612                 }
1613
1614                 if ( isset( $noKeyOptions['SQL_BIG_RESULT'] ) ) {
1615                         $startOpts .= ' SQL_BIG_RESULT';
1616                 }
1617
1618                 if ( isset( $noKeyOptions['SQL_BUFFER_RESULT'] ) ) {
1619                         $startOpts .= ' SQL_BUFFER_RESULT';
1620                 }
1621
1622                 if ( isset( $noKeyOptions['SQL_SMALL_RESULT'] ) ) {
1623                         $startOpts .= ' SQL_SMALL_RESULT';
1624                 }
1625
1626                 if ( isset( $noKeyOptions['SQL_CALC_FOUND_ROWS'] ) ) {
1627                         $startOpts .= ' SQL_CALC_FOUND_ROWS';
1628                 }
1629
1630                 if ( isset( $noKeyOptions['SQL_CACHE'] ) ) {
1631                         $startOpts .= ' SQL_CACHE';
1632                 }
1633
1634                 if ( isset( $noKeyOptions['SQL_NO_CACHE'] ) ) {
1635                         $startOpts .= ' SQL_NO_CACHE';
1636                 }
1637
1638                 if ( isset( $options['USE INDEX'] ) && is_string( $options['USE INDEX'] ) ) {
1639                         $useIndex = $this->useIndexClause( $options['USE INDEX'] );
1640                 } else {
1641                         $useIndex = '';
1642                 }
1643                 if ( isset( $options['IGNORE INDEX'] ) && is_string( $options['IGNORE INDEX'] ) ) {
1644                         $ignoreIndex = $this->ignoreIndexClause( $options['IGNORE INDEX'] );
1645                 } else {
1646                         $ignoreIndex = '';
1647                 }
1648
1649                 return [ $startOpts, $useIndex, $preLimitTail, $postLimitTail, $ignoreIndex ];
1650         }
1651
1652         /**
1653          * Returns an optional GROUP BY with an optional HAVING
1654          *
1655          * @param array $options Associative array of options
1656          * @return string
1657          * @see Database::select()
1658          * @since 1.21
1659          */
1660         protected function makeGroupByWithHaving( $options ) {
1661                 $sql = '';
1662                 if ( isset( $options['GROUP BY'] ) ) {
1663                         $gb = is_array( $options['GROUP BY'] )
1664                                 ? implode( ',', $options['GROUP BY'] )
1665                                 : $options['GROUP BY'];
1666                         $sql .= ' GROUP BY ' . $gb;
1667                 }
1668                 if ( isset( $options['HAVING'] ) ) {
1669                         $having = is_array( $options['HAVING'] )
1670                                 ? $this->makeList( $options['HAVING'], self::LIST_AND )
1671                                 : $options['HAVING'];
1672                         $sql .= ' HAVING ' . $having;
1673                 }
1674
1675                 return $sql;
1676         }
1677
1678         /**
1679          * Returns an optional ORDER BY
1680          *
1681          * @param array $options Associative array of options
1682          * @return string
1683          * @see Database::select()
1684          * @since 1.21
1685          */
1686         protected function makeOrderBy( $options ) {
1687                 if ( isset( $options['ORDER BY'] ) ) {
1688                         $ob = is_array( $options['ORDER BY'] )
1689                                 ? implode( ',', $options['ORDER BY'] )
1690                                 : $options['ORDER BY'];
1691
1692                         return ' ORDER BY ' . $ob;
1693                 }
1694
1695                 return '';
1696         }
1697
1698         public function select(
1699                 $table, $vars, $conds = '', $fname = __METHOD__, $options = [], $join_conds = []
1700         ) {
1701                 $sql = $this->selectSQLText( $table, $vars, $conds, $fname, $options, $join_conds );
1702
1703                 return $this->query( $sql, $fname );
1704         }
1705
1706         public function selectSQLText( $table, $vars, $conds = '', $fname = __METHOD__,
1707                 $options = [], $join_conds = []
1708         ) {
1709                 if ( is_array( $vars ) ) {
1710                         $fields = implode( ',', $this->fieldNamesWithAlias( $vars ) );
1711                 } else {
1712                         $fields = $vars;
1713                 }
1714
1715                 $options = (array)$options;
1716                 $useIndexes = ( isset( $options['USE INDEX'] ) && is_array( $options['USE INDEX'] ) )
1717                         ? $options['USE INDEX']
1718                         : [];
1719                 $ignoreIndexes = (
1720                         isset( $options['IGNORE INDEX'] ) &&
1721                         is_array( $options['IGNORE INDEX'] )
1722                 )
1723                         ? $options['IGNORE INDEX']
1724                         : [];
1725
1726                 if (
1727                         $this->selectOptionsIncludeLocking( $options ) &&
1728                         $this->selectFieldsOrOptionsAggregate( $vars, $options )
1729                 ) {
1730                         // Some DB types (postgres/oracle) disallow FOR UPDATE with aggregate
1731                         // functions. Discourage use of such queries to encourage compatibility.
1732                         call_user_func(
1733                                 $this->deprecationLogger,
1734                                 __METHOD__ . ": aggregation used with a locking SELECT ($fname)."
1735                         );
1736                 }
1737
1738                 if ( is_array( $table ) ) {
1739                         $from = ' FROM ' .
1740                                 $this->tableNamesWithIndexClauseOrJOIN(
1741                                         $table, $useIndexes, $ignoreIndexes, $join_conds );
1742                 } elseif ( $table != '' ) {
1743                         $from = ' FROM ' .
1744                                 $this->tableNamesWithIndexClauseOrJOIN(
1745                                         [ $table ], $useIndexes, $ignoreIndexes, [] );
1746                 } else {
1747                         $from = '';
1748                 }
1749
1750                 list( $startOpts, $useIndex, $preLimitTail, $postLimitTail, $ignoreIndex ) =
1751                         $this->makeSelectOptions( $options );
1752
1753                 if ( is_array( $conds ) ) {
1754                         $conds = $this->makeList( $conds, self::LIST_AND );
1755                 }
1756
1757                 if ( $conds === null || $conds === false ) {
1758                         $this->queryLogger->warning(
1759                                 __METHOD__
1760                                 . ' called from '
1761                                 . $fname
1762                                 . ' with incorrect parameters: $conds must be a string or an array'
1763                         );
1764                         $conds = '';
1765                 }
1766
1767                 if ( $conds === '' || $conds === '*' ) {
1768                         $sql = "SELECT $startOpts $fields $from $useIndex $ignoreIndex $preLimitTail";
1769                 } elseif ( is_string( $conds ) ) {
1770                         $sql = "SELECT $startOpts $fields $from $useIndex $ignoreIndex " .
1771                                 "WHERE $conds $preLimitTail";
1772                 } else {
1773                         throw new DBUnexpectedError( $this, __METHOD__ . ' called with incorrect parameters' );
1774                 }
1775
1776                 if ( isset( $options['LIMIT'] ) ) {
1777                         $sql = $this->limitResult( $sql, $options['LIMIT'],
1778                                 $options['OFFSET'] ?? false );
1779                 }
1780                 $sql = "$sql $postLimitTail";
1781
1782                 if ( isset( $options['EXPLAIN'] ) ) {
1783                         $sql = 'EXPLAIN ' . $sql;
1784                 }
1785
1786                 return $sql;
1787         }
1788
1789         public function selectRow( $table, $vars, $conds, $fname = __METHOD__,
1790                 $options = [], $join_conds = []
1791         ) {
1792                 $options = (array)$options;
1793                 $options['LIMIT'] = 1;
1794                 $res = $this->select( $table, $vars, $conds, $fname, $options, $join_conds );
1795
1796                 if ( $res === false ) {
1797                         return false;
1798                 }
1799
1800                 if ( !$this->numRows( $res ) ) {
1801                         return false;
1802                 }
1803
1804                 $obj = $this->fetchObject( $res );
1805
1806                 return $obj;
1807         }
1808
1809         public function estimateRowCount(
1810                 $table, $var = '*', $conds = '', $fname = __METHOD__, $options = [], $join_conds = []
1811         ) {
1812                 $conds = $this->normalizeConditions( $conds, $fname );
1813                 $column = $this->extractSingleFieldFromList( $var );
1814                 if ( is_string( $column ) && !in_array( $column, [ '*', '1' ] ) ) {
1815                         $conds[] = "$column IS NOT NULL";
1816                 }
1817
1818                 $res = $this->select(
1819                         $table, [ 'rowcount' => 'COUNT(*)' ], $conds, $fname, $options, $join_conds
1820                 );
1821                 $row = $res ? $this->fetchRow( $res ) : [];
1822
1823                 return isset( $row['rowcount'] ) ? (int)$row['rowcount'] : 0;
1824         }
1825
1826         public function selectRowCount(
1827                 $tables, $var = '*', $conds = '', $fname = __METHOD__, $options = [], $join_conds = []
1828         ) {
1829                 $conds = $this->normalizeConditions( $conds, $fname );
1830                 $column = $this->extractSingleFieldFromList( $var );
1831                 if ( is_string( $column ) && !in_array( $column, [ '*', '1' ] ) ) {
1832                         $conds[] = "$column IS NOT NULL";
1833                 }
1834
1835                 $res = $this->select(
1836                         [
1837                                 'tmp_count' => $this->buildSelectSubquery(
1838                                         $tables,
1839                                         '1',
1840                                         $conds,
1841                                         $fname,
1842                                         $options,
1843                                         $join_conds
1844                                 )
1845                         ],
1846                         [ 'rowcount' => 'COUNT(*)' ],
1847                         [],
1848                         $fname
1849                 );
1850                 $row = $res ? $this->fetchRow( $res ) : [];
1851
1852                 return isset( $row['rowcount'] ) ? (int)$row['rowcount'] : 0;
1853         }
1854
1855         /**
1856          * @param string|array $options
1857          * @return bool
1858          */
1859         private function selectOptionsIncludeLocking( $options ) {
1860                 $options = (array)$options;
1861                 foreach ( [ 'FOR UPDATE', 'LOCK IN SHARE MODE' ] as $lock ) {
1862                         if ( in_array( $lock, $options, true ) ) {
1863                                 return true;
1864                         }
1865                 }
1866
1867                 return false;
1868         }
1869
1870         /**
1871          * @param array|string $fields
1872          * @param array|string $options
1873          * @return bool
1874          */
1875         private function selectFieldsOrOptionsAggregate( $fields, $options ) {
1876                 foreach ( (array)$options as $key => $value ) {
1877                         if ( is_string( $key ) ) {
1878                                 if ( preg_match( '/^(?:GROUP BY|HAVING)$/i', $key ) ) {
1879                                         return true;
1880                                 }
1881                         } elseif ( is_string( $value ) ) {
1882                                 if ( preg_match( '/^(?:DISTINCT|DISTINCTROW)$/i', $value ) ) {
1883                                         return true;
1884                                 }
1885                         }
1886                 }
1887
1888                 $regex = '/^(?:COUNT|MIN|MAX|SUM|GROUP_CONCAT|LISTAGG|ARRAY_AGG)\s*\\(/i';
1889                 foreach ( (array)$fields as $field ) {
1890                         if ( is_string( $field ) && preg_match( $regex, $field ) ) {
1891                                 return true;
1892                         }
1893                 }
1894
1895                 return false;
1896         }
1897
1898         /**
1899          * @param array|string $conds
1900          * @param string $fname
1901          * @return array
1902          */
1903         final protected function normalizeConditions( $conds, $fname ) {
1904                 if ( $conds === null || $conds === false ) {
1905                         $this->queryLogger->warning(
1906                                 __METHOD__
1907                                 . ' called from '
1908                                 . $fname
1909                                 . ' with incorrect parameters: $conds must be a string or an array'
1910                         );
1911                         $conds = '';
1912                 }
1913
1914                 if ( !is_array( $conds ) ) {
1915                         $conds = ( $conds === '' ) ? [] : [ $conds ];
1916                 }
1917
1918                 return $conds;
1919         }
1920
1921         /**
1922          * @param array|string $var Field parameter in the style of select()
1923          * @return string|null Column name or null; ignores aliases
1924          * @throws DBUnexpectedError Errors out if multiple columns are given
1925          */
1926         final protected function extractSingleFieldFromList( $var ) {
1927                 if ( is_array( $var ) ) {
1928                         if ( !$var ) {
1929                                 $column = null;
1930                         } elseif ( count( $var ) == 1 ) {
1931                                 $column = $var[0] ?? reset( $var );
1932                         } else {
1933                                 throw new DBUnexpectedError( $this, __METHOD__ . ': got multiple columns.' );
1934                         }
1935                 } else {
1936                         $column = $var;
1937                 }
1938
1939                 return $column;
1940         }
1941
1942         public function lockForUpdate(
1943                 $table, $conds = '', $fname = __METHOD__, $options = [], $join_conds = []
1944         ) {
1945                 if ( !$this->trxLevel && !$this->getFlag( self::DBO_TRX ) ) {
1946                         throw new DBUnexpectedError(
1947                                 $this,
1948                                 __METHOD__ . ': no transaction is active nor is DBO_TRX set'
1949                         );
1950                 }
1951
1952                 $options = (array)$options;
1953                 $options[] = 'FOR UPDATE';
1954
1955                 return $this->selectRowCount( $table, '*', $conds, $fname, $options, $join_conds );
1956         }
1957
1958         /**
1959          * Removes most variables from an SQL query and replaces them with X or N for numbers.
1960          * It's only slightly flawed. Don't use for anything important.
1961          *
1962          * @param string $sql A SQL Query
1963          *
1964          * @return string
1965          */
1966         protected static function generalizeSQL( $sql ) {
1967                 # This does the same as the regexp below would do, but in such a way
1968                 # as to avoid crashing php on some large strings.
1969                 # $sql = preg_replace( "/'([^\\\\']|\\\\.)*'|\"([^\\\\\"]|\\\\.)*\"/", "'X'", $sql );
1970
1971                 $sql = str_replace( "\\\\", '', $sql );
1972                 $sql = str_replace( "\\'", '', $sql );
1973                 $sql = str_replace( "\\\"", '', $sql );
1974                 $sql = preg_replace( "/'.*'/s", "'X'", $sql );
1975                 $sql = preg_replace( '/".*"/s', "'X'", $sql );
1976
1977                 # All newlines, tabs, etc replaced by single space
1978                 $sql = preg_replace( '/\s+/', ' ', $sql );
1979
1980                 # All numbers => N,
1981                 # except the ones surrounded by characters, e.g. l10n
1982                 $sql = preg_replace( '/-?\d+(,-?\d+)+/s', 'N,...,N', $sql );
1983                 $sql = preg_replace( '/(?<![a-zA-Z])-?\d+(?![a-zA-Z])/s', 'N', $sql );
1984
1985                 return $sql;
1986         }
1987
1988         public function fieldExists( $table, $field, $fname = __METHOD__ ) {
1989                 $info = $this->fieldInfo( $table, $field );
1990
1991                 return (bool)$info;
1992         }
1993
1994         public function indexExists( $table, $index, $fname = __METHOD__ ) {
1995                 if ( !$this->tableExists( $table ) ) {
1996                         return null;
1997                 }
1998
1999                 $info = $this->indexInfo( $table, $index, $fname );
2000                 if ( is_null( $info ) ) {
2001                         return null;
2002                 } else {
2003                         return $info !== false;
2004                 }
2005         }
2006
2007         abstract public function tableExists( $table, $fname = __METHOD__ );
2008
2009         public function indexUnique( $table, $index ) {
2010                 $indexInfo = $this->indexInfo( $table, $index );
2011
2012                 if ( !$indexInfo ) {
2013                         return null;
2014                 }
2015
2016                 return !$indexInfo[0]->Non_unique;
2017         }
2018
2019         /**
2020          * Helper for Database::insert().
2021          *
2022          * @param array $options
2023          * @return string
2024          */
2025         protected function makeInsertOptions( $options ) {
2026                 return implode( ' ', $options );
2027         }
2028
2029         public function insert( $table, $a, $fname = __METHOD__, $options = [] ) {
2030                 # No rows to insert, easy just return now
2031                 if ( !count( $a ) ) {
2032                         return true;
2033                 }
2034
2035                 $table = $this->tableName( $table );
2036
2037                 if ( !is_array( $options ) ) {
2038                         $options = [ $options ];
2039                 }
2040
2041                 $options = $this->makeInsertOptions( $options );
2042
2043                 if ( isset( $a[0] ) && is_array( $a[0] ) ) {
2044                         $multi = true;
2045                         $keys = array_keys( $a[0] );
2046                 } else {
2047                         $multi = false;
2048                         $keys = array_keys( $a );
2049                 }
2050
2051                 $sql = 'INSERT ' . $options .
2052                         " INTO $table (" . implode( ',', $keys ) . ') VALUES ';
2053
2054                 if ( $multi ) {
2055                         $first = true;
2056                         foreach ( $a as $row ) {
2057                                 if ( $first ) {
2058                                         $first = false;
2059                                 } else {
2060                                         $sql .= ',';
2061                                 }
2062                                 $sql .= '(' . $this->makeList( $row ) . ')';
2063                         }
2064                 } else {
2065                         $sql .= '(' . $this->makeList( $a ) . ')';
2066                 }
2067
2068                 $this->query( $sql, $fname );
2069
2070                 return true;
2071         }
2072
2073         /**
2074          * Make UPDATE options array for Database::makeUpdateOptions
2075          *
2076          * @param array $options
2077          * @return array
2078          */
2079         protected function makeUpdateOptionsArray( $options ) {
2080                 if ( !is_array( $options ) ) {
2081                         $options = [ $options ];
2082                 }
2083
2084                 $opts = [];
2085
2086                 if ( in_array( 'IGNORE', $options ) ) {
2087                         $opts[] = 'IGNORE';
2088                 }
2089
2090                 return $opts;
2091         }
2092
2093         /**
2094          * Make UPDATE options for the Database::update function
2095          *
2096          * @param array $options The options passed to Database::update
2097          * @return string
2098          */
2099         protected function makeUpdateOptions( $options ) {
2100                 $opts = $this->makeUpdateOptionsArray( $options );
2101
2102                 return implode( ' ', $opts );
2103         }
2104
2105         public function update( $table, $values, $conds, $fname = __METHOD__, $options = [] ) {
2106                 $table = $this->tableName( $table );
2107                 $opts = $this->makeUpdateOptions( $options );
2108                 $sql = "UPDATE $opts $table SET " . $this->makeList( $values, self::LIST_SET );
2109
2110                 if ( $conds !== [] && $conds !== '*' ) {
2111                         $sql .= " WHERE " . $this->makeList( $conds, self::LIST_AND );
2112                 }
2113
2114                 $this->query( $sql, $fname );
2115
2116                 return true;
2117         }
2118
2119         public function makeList( $a, $mode = self::LIST_COMMA ) {
2120                 if ( !is_array( $a ) ) {
2121                         throw new DBUnexpectedError( $this, __METHOD__ . ' called with incorrect parameters' );
2122                 }
2123
2124                 $first = true;
2125                 $list = '';
2126
2127                 foreach ( $a as $field => $value ) {
2128                         if ( !$first ) {
2129                                 if ( $mode == self::LIST_AND ) {
2130                                         $list .= ' AND ';
2131                                 } elseif ( $mode == self::LIST_OR ) {
2132                                         $list .= ' OR ';
2133                                 } else {
2134                                         $list .= ',';
2135                                 }
2136                         } else {
2137                                 $first = false;
2138                         }
2139
2140                         if ( ( $mode == self::LIST_AND || $mode == self::LIST_OR ) && is_numeric( $field ) ) {
2141                                 $list .= "($value)";
2142                         } elseif ( $mode == self::LIST_SET && is_numeric( $field ) ) {
2143                                 $list .= "$value";
2144                         } elseif (
2145                                 ( $mode == self::LIST_AND || $mode == self::LIST_OR ) && is_array( $value )
2146                         ) {
2147                                 // Remove null from array to be handled separately if found
2148                                 $includeNull = false;
2149                                 foreach ( array_keys( $value, null, true ) as $nullKey ) {
2150                                         $includeNull = true;
2151                                         unset( $value[$nullKey] );
2152                                 }
2153                                 if ( count( $value ) == 0 && !$includeNull ) {
2154                                         throw new InvalidArgumentException(
2155                                                 __METHOD__ . ": empty input for field $field" );
2156                                 } elseif ( count( $value ) == 0 ) {
2157                                         // only check if $field is null
2158                                         $list .= "$field IS NULL";
2159                                 } else {
2160                                         // IN clause contains at least one valid element
2161                                         if ( $includeNull ) {
2162                                                 // Group subconditions to ensure correct precedence
2163                                                 $list .= '(';
2164                                         }
2165                                         if ( count( $value ) == 1 ) {
2166                                                 // Special-case single values, as IN isn't terribly efficient
2167                                                 // Don't necessarily assume the single key is 0; we don't
2168                                                 // enforce linear numeric ordering on other arrays here.
2169                                                 $value = array_values( $value )[0];
2170                                                 $list .= $field . " = " . $this->addQuotes( $value );
2171                                         } else {
2172                                                 $list .= $field . " IN (" . $this->makeList( $value ) . ") ";
2173                                         }
2174                                         // if null present in array, append IS NULL
2175                                         if ( $includeNull ) {
2176                                                 $list .= " OR $field IS NULL)";
2177                                         }
2178                                 }
2179                         } elseif ( $value === null ) {
2180                                 if ( $mode == self::LIST_AND || $mode == self::LIST_OR ) {
2181                                         $list .= "$field IS ";
2182                                 } elseif ( $mode == self::LIST_SET ) {
2183                                         $list .= "$field = ";
2184                                 }
2185                                 $list .= 'NULL';
2186                         } else {
2187                                 if (
2188                                         $mode == self::LIST_AND || $mode == self::LIST_OR || $mode == self::LIST_SET
2189                                 ) {
2190                                         $list .= "$field = ";
2191                                 }
2192                                 $list .= $mode == self::LIST_NAMES ? $value : $this->addQuotes( $value );
2193                         }
2194                 }
2195
2196                 return $list;
2197         }
2198
2199         public function makeWhereFrom2d( $data, $baseKey, $subKey ) {
2200                 $conds = [];
2201
2202                 foreach ( $data as $base => $sub ) {
2203                         if ( count( $sub ) ) {
2204                                 $conds[] = $this->makeList(
2205                                         [ $baseKey => $base, $subKey => array_keys( $sub ) ],
2206                                         self::LIST_AND );
2207                         }
2208                 }
2209
2210                 if ( $conds ) {
2211                         return $this->makeList( $conds, self::LIST_OR );
2212                 } else {
2213                         // Nothing to search for...
2214                         return false;
2215                 }
2216         }
2217
2218         public function aggregateValue( $valuedata, $valuename = 'value' ) {
2219                 return $valuename;
2220         }
2221
2222         public function bitNot( $field ) {
2223                 return "(~$field)";
2224         }
2225
2226         public function bitAnd( $fieldLeft, $fieldRight ) {
2227                 return "($fieldLeft & $fieldRight)";
2228         }
2229
2230         public function bitOr( $fieldLeft, $fieldRight ) {
2231                 return "($fieldLeft | $fieldRight)";
2232         }
2233
2234         public function buildConcat( $stringList ) {
2235                 return 'CONCAT(' . implode( ',', $stringList ) . ')';
2236         }
2237
2238         public function buildGroupConcatField(
2239                 $delim, $table, $field, $conds = '', $join_conds = []
2240         ) {
2241                 $fld = "GROUP_CONCAT($field SEPARATOR " . $this->addQuotes( $delim ) . ')';
2242
2243                 return '(' . $this->selectSQLText( $table, $fld, $conds, null, [], $join_conds ) . ')';
2244         }
2245
2246         public function buildSubstring( $input, $startPosition, $length = null ) {
2247                 $this->assertBuildSubstringParams( $startPosition, $length );
2248                 $functionBody = "$input FROM $startPosition";
2249                 if ( $length !== null ) {
2250                         $functionBody .= " FOR $length";
2251                 }
2252                 return 'SUBSTRING(' . $functionBody . ')';
2253         }
2254
2255         /**
2256          * Check type and bounds for parameters to self::buildSubstring()
2257          *
2258          * All supported databases have substring functions that behave the same for
2259          * positive $startPosition and non-negative $length, but behaviors differ when
2260          * given 0 or negative $startPosition or negative $length. The simplest
2261          * solution to that is to just forbid those values.
2262          *
2263          * @param int $startPosition
2264          * @param int|null $length
2265          * @since 1.31
2266          */
2267         protected function assertBuildSubstringParams( $startPosition, $length ) {
2268                 if ( !is_int( $startPosition ) || $startPosition <= 0 ) {
2269                         throw new InvalidArgumentException(
2270                                 '$startPosition must be a positive integer'
2271                         );
2272                 }
2273                 if ( !( is_int( $length ) && $length >= 0 || $length === null ) ) {
2274                         throw new InvalidArgumentException(
2275                                 '$length must be null or an integer greater than or equal to 0'
2276                         );
2277                 }
2278         }
2279
2280         public function buildStringCast( $field ) {
2281                 return $field;
2282         }
2283
2284         public function buildIntegerCast( $field ) {
2285                 return 'CAST( ' . $field . ' AS INTEGER )';
2286         }
2287
2288         public function buildSelectSubquery(
2289                 $table, $vars, $conds = '', $fname = __METHOD__,
2290                 $options = [], $join_conds = []
2291         ) {
2292                 return new Subquery(
2293                         $this->selectSQLText( $table, $vars, $conds, $fname, $options, $join_conds )
2294                 );
2295         }
2296
2297         public function databasesAreIndependent() {
2298                 return false;
2299         }
2300
2301         final public function selectDB( $db ) {
2302                 $this->selectDomain( new DatabaseDomain(
2303                         $db,
2304                         $this->currentDomain->getSchema(),
2305                         $this->currentDomain->getTablePrefix()
2306                 ) );
2307
2308                 return true;
2309         }
2310
2311         final public function selectDomain( $domain ) {
2312                 $this->doSelectDomain( DatabaseDomain::newFromId( $domain ) );
2313         }
2314
2315         protected function doSelectDomain( DatabaseDomain $domain ) {
2316                 $this->currentDomain = $domain;
2317         }
2318
2319         public function getDBname() {
2320                 return $this->currentDomain->getDatabase();
2321         }
2322
2323         public function getServer() {
2324                 return $this->server;
2325         }
2326
2327         public function tableName( $name, $format = 'quoted' ) {
2328                 if ( $name instanceof Subquery ) {
2329                         throw new DBUnexpectedError(
2330                                 $this,
2331                                 __METHOD__ . ': got Subquery instance when expecting a string.'
2332                         );
2333                 }
2334
2335                 # Skip the entire process when we have a string quoted on both ends.
2336                 # Note that we check the end so that we will still quote any use of
2337                 # use of `database`.table. But won't break things if someone wants
2338                 # to query a database table with a dot in the name.
2339                 if ( $this->isQuotedIdentifier( $name ) ) {
2340                         return $name;
2341                 }
2342
2343                 # Lets test for any bits of text that should never show up in a table
2344                 # name. Basically anything like JOIN or ON which are actually part of
2345                 # SQL queries, but may end up inside of the table value to combine
2346                 # sql. Such as how the API is doing.
2347                 # Note that we use a whitespace test rather than a \b test to avoid
2348                 # any remote case where a word like on may be inside of a table name
2349                 # surrounded by symbols which may be considered word breaks.
2350                 if ( preg_match( '/(^|\s)(DISTINCT|JOIN|ON|AS)(\s|$)/i', $name ) !== 0 ) {
2351                         $this->queryLogger->warning(
2352                                 __METHOD__ . ": use of subqueries is not supported this way.",
2353                                 [ 'trace' => ( new RuntimeException() )->getTraceAsString() ]
2354                         );
2355
2356                         return $name;
2357                 }
2358
2359                 # Split database and table into proper variables.
2360                 list( $database, $schema, $prefix, $table ) = $this->qualifiedTableComponents( $name );
2361
2362                 # Quote $table and apply the prefix if not quoted.
2363                 # $tableName might be empty if this is called from Database::replaceVars()
2364                 $tableName = "{$prefix}{$table}";
2365                 if ( $format === 'quoted'
2366                         && !$this->isQuotedIdentifier( $tableName )
2367                         && $tableName !== ''
2368                 ) {
2369                         $tableName = $this->addIdentifierQuotes( $tableName );
2370                 }
2371
2372                 # Quote $schema and $database and merge them with the table name if needed
2373                 $tableName = $this->prependDatabaseOrSchema( $schema, $tableName, $format );
2374                 $tableName = $this->prependDatabaseOrSchema( $database, $tableName, $format );
2375
2376                 return $tableName;
2377         }
2378
2379         /**
2380          * Get the table components needed for a query given the currently selected database
2381          *
2382          * @param string $name Table name in the form of db.schema.table, db.table, or table
2383          * @return array (DB name or "" for default, schema name, table prefix, table name)
2384          */
2385         protected function qualifiedTableComponents( $name ) {
2386                 # We reverse the explode so that database.table and table both output the correct table.
2387                 $dbDetails = explode( '.', $name, 3 );
2388                 if ( count( $dbDetails ) == 3 ) {
2389                         list( $database, $schema, $table ) = $dbDetails;
2390                         # We don't want any prefix added in this case
2391                         $prefix = '';
2392                 } elseif ( count( $dbDetails ) == 2 ) {
2393                         list( $database, $table ) = $dbDetails;
2394                         # We don't want any prefix added in this case
2395                         $prefix = '';
2396                         # In dbs that support it, $database may actually be the schema
2397                         # but that doesn't affect any of the functionality here
2398                         $schema = '';
2399                 } else {
2400                         list( $table ) = $dbDetails;
2401                         if ( isset( $this->tableAliases[$table] ) ) {
2402                                 $database = $this->tableAliases[$table]['dbname'];
2403                                 $schema = is_string( $this->tableAliases[$table]['schema'] )
2404                                         ? $this->tableAliases[$table]['schema']
2405                                         : $this->relationSchemaQualifier();
2406                                 $prefix = is_string( $this->tableAliases[$table]['prefix'] )
2407                                         ? $this->tableAliases[$table]['prefix']
2408                                         : $this->tablePrefix();
2409                         } else {
2410                                 $database = '';
2411                                 $schema = $this->relationSchemaQualifier(); # Default schema
2412                                 $prefix = $this->tablePrefix(); # Default prefix
2413                         }
2414                 }
2415
2416                 return [ $database, $schema, $prefix, $table ];
2417         }
2418
2419         /**
2420          * @param string|null $namespace Database or schema
2421          * @param string $relation Name of table, view, sequence, etc...
2422          * @param string $format One of (raw, quoted)
2423          * @return string Relation name with quoted and merged $namespace as needed
2424          */
2425         private function prependDatabaseOrSchema( $namespace, $relation, $format ) {
2426                 if ( strlen( $namespace ) ) {
2427                         if ( $format === 'quoted' && !$this->isQuotedIdentifier( $namespace ) ) {
2428                                 $namespace = $this->addIdentifierQuotes( $namespace );
2429                         }
2430                         $relation = $namespace . '.' . $relation;
2431                 }
2432
2433                 return $relation;
2434         }
2435
2436         public function tableNames() {
2437                 $inArray = func_get_args();
2438                 $retVal = [];
2439
2440                 foreach ( $inArray as $name ) {
2441                         $retVal[$name] = $this->tableName( $name );
2442                 }
2443
2444                 return $retVal;
2445         }
2446
2447         public function tableNamesN() {
2448                 $inArray = func_get_args();
2449                 $retVal = [];
2450
2451                 foreach ( $inArray as $name ) {
2452                         $retVal[] = $this->tableName( $name );
2453                 }
2454
2455                 return $retVal;
2456         }
2457
2458         /**
2459          * Get an aliased table name
2460          *
2461          * This returns strings like "tableName AS newTableName" for aliased tables
2462          * and "(SELECT * from tableA) newTablename" for subqueries (e.g. derived tables)
2463          *
2464          * @see Database::tableName()
2465          * @param string|Subquery $table Table name or object with a 'sql' field
2466          * @param string|bool $alias Table alias (optional)
2467          * @return string SQL name for aliased table. Will not alias a table to its own name
2468          */
2469         protected function tableNameWithAlias( $table, $alias = false ) {
2470                 if ( is_string( $table ) ) {
2471                         $quotedTable = $this->tableName( $table );
2472                 } elseif ( $table instanceof Subquery ) {
2473                         $quotedTable = (string)$table;
2474                 } else {
2475                         throw new InvalidArgumentException( "Table must be a string or Subquery." );
2476                 }
2477
2478                 if ( !strlen( $alias ) || $alias === $table ) {
2479                         if ( $table instanceof Subquery ) {
2480                                 throw new InvalidArgumentException( "Subquery table missing alias." );
2481                         }
2482
2483                         return $quotedTable;
2484                 } else {
2485                         return $quotedTable . ' ' . $this->addIdentifierQuotes( $alias );
2486                 }
2487         }
2488
2489         /**
2490          * Gets an array of aliased table names
2491          *
2492          * @param array $tables [ [alias] => table ]
2493          * @return string[] See tableNameWithAlias()
2494          */
2495         protected function tableNamesWithAlias( $tables ) {
2496                 $retval = [];
2497                 foreach ( $tables as $alias => $table ) {
2498                         if ( is_numeric( $alias ) ) {
2499                                 $alias = $table;
2500                         }
2501                         $retval[] = $this->tableNameWithAlias( $table, $alias );
2502                 }
2503
2504                 return $retval;
2505         }
2506
2507         /**
2508          * Get an aliased field name
2509          * e.g. fieldName AS newFieldName
2510          *
2511          * @param string $name Field name
2512          * @param string|bool $alias Alias (optional)
2513          * @return string SQL name for aliased field. Will not alias a field to its own name
2514          */
2515         protected function fieldNameWithAlias( $name, $alias = false ) {
2516                 if ( !$alias || (string)$alias === (string)$name ) {
2517                         return $name;
2518                 } else {
2519                         return $name . ' AS ' . $this->addIdentifierQuotes( $alias ); // PostgreSQL needs AS
2520                 }
2521         }
2522
2523         /**
2524          * Gets an array of aliased field names
2525          *
2526          * @param array $fields [ [alias] => field ]
2527          * @return string[] See fieldNameWithAlias()
2528          */
2529         protected function fieldNamesWithAlias( $fields ) {
2530                 $retval = [];
2531                 foreach ( $fields as $alias => $field ) {
2532                         if ( is_numeric( $alias ) ) {
2533                                 $alias = $field;
2534                         }
2535                         $retval[] = $this->fieldNameWithAlias( $field, $alias );
2536                 }
2537
2538                 return $retval;
2539         }
2540
2541         /**
2542          * Get the aliased table name clause for a FROM clause
2543          * which might have a JOIN and/or USE INDEX or IGNORE INDEX clause
2544          *
2545          * @param array $tables ( [alias] => table )
2546          * @param array $use_index Same as for select()
2547          * @param array $ignore_index Same as for select()
2548          * @param array $join_conds Same as for select()
2549          * @return string
2550          */
2551         protected function tableNamesWithIndexClauseOrJOIN(
2552                 $tables, $use_index = [], $ignore_index = [], $join_conds = []
2553         ) {
2554                 $ret = [];
2555                 $retJOIN = [];
2556                 $use_index = (array)$use_index;
2557                 $ignore_index = (array)$ignore_index;
2558                 $join_conds = (array)$join_conds;
2559
2560                 foreach ( $tables as $alias => $table ) {
2561                         if ( !is_string( $alias ) ) {
2562                                 // No alias? Set it equal to the table name
2563                                 $alias = $table;
2564                         }
2565
2566                         if ( is_array( $table ) ) {
2567                                 // A parenthesized group
2568                                 if ( count( $table ) > 1 ) {
2569                                         $joinedTable = '(' .
2570                                                 $this->tableNamesWithIndexClauseOrJOIN(
2571                                                         $table, $use_index, $ignore_index, $join_conds ) . ')';
2572                                 } else {
2573                                         // Degenerate case
2574                                         $innerTable = reset( $table );
2575                                         $innerAlias = key( $table );
2576                                         $joinedTable = $this->tableNameWithAlias(
2577                                                 $innerTable,
2578                                                 is_string( $innerAlias ) ? $innerAlias : $innerTable
2579                                         );
2580                                 }
2581                         } else {
2582                                 $joinedTable = $this->tableNameWithAlias( $table, $alias );
2583                         }
2584
2585                         // Is there a JOIN clause for this table?
2586                         if ( isset( $join_conds[$alias] ) ) {
2587                                 list( $joinType, $conds ) = $join_conds[$alias];
2588                                 $tableClause = $joinType;
2589                                 $tableClause .= ' ' . $joinedTable;
2590                                 if ( isset( $use_index[$alias] ) ) { // has USE INDEX?
2591                                         $use = $this->useIndexClause( implode( ',', (array)$use_index[$alias] ) );
2592                                         if ( $use != '' ) {
2593                                                 $tableClause .= ' ' . $use;
2594                                         }
2595                                 }
2596                                 if ( isset( $ignore_index[$alias] ) ) { // has IGNORE INDEX?
2597                                         $ignore = $this->ignoreIndexClause(
2598                                                 implode( ',', (array)$ignore_index[$alias] ) );
2599                                         if ( $ignore != '' ) {
2600                                                 $tableClause .= ' ' . $ignore;
2601                                         }
2602                                 }
2603                                 $on = $this->makeList( (array)$conds, self::LIST_AND );
2604                                 if ( $on != '' ) {
2605                                         $tableClause .= ' ON (' . $on . ')';
2606                                 }
2607
2608                                 $retJOIN[] = $tableClause;
2609                         } elseif ( isset( $use_index[$alias] ) ) {
2610                                 // Is there an INDEX clause for this table?
2611                                 $tableClause = $joinedTable;
2612                                 $tableClause .= ' ' . $this->useIndexClause(
2613                                                 implode( ',', (array)$use_index[$alias] )
2614                                         );
2615
2616                                 $ret[] = $tableClause;
2617                         } elseif ( isset( $ignore_index[$alias] ) ) {
2618                                 // Is there an INDEX clause for this table?
2619                                 $tableClause = $joinedTable;
2620                                 $tableClause .= ' ' . $this->ignoreIndexClause(
2621                                                 implode( ',', (array)$ignore_index[$alias] )
2622                                         );
2623
2624                                 $ret[] = $tableClause;
2625                         } else {
2626                                 $tableClause = $joinedTable;
2627
2628                                 $ret[] = $tableClause;
2629                         }
2630                 }
2631
2632                 // We can't separate explicit JOIN clauses with ',', use ' ' for those
2633                 $implicitJoins = $ret ? implode( ',', $ret ) : "";
2634                 $explicitJoins = $retJOIN ? implode( ' ', $retJOIN ) : "";
2635
2636                 // Compile our final table clause
2637                 return implode( ' ', [ $implicitJoins, $explicitJoins ] );
2638         }
2639
2640         /**
2641          * Allows for index remapping in queries where this is not consistent across DBMS
2642          *
2643          * @param string $index
2644          * @return string
2645          */
2646         protected function indexName( $index ) {
2647                 return $this->indexAliases[$index] ?? $index;
2648         }
2649
2650         public function addQuotes( $s ) {
2651                 if ( $s instanceof Blob ) {
2652                         $s = $s->fetch();
2653                 }
2654                 if ( $s === null ) {
2655                         return 'NULL';
2656                 } elseif ( is_bool( $s ) ) {
2657                         return (int)$s;
2658                 } else {
2659                         # This will also quote numeric values. This should be harmless,
2660                         # and protects against weird problems that occur when they really
2661                         # _are_ strings such as article titles and string->number->string
2662                         # conversion is not 1:1.
2663                         return "'" . $this->strencode( $s ) . "'";
2664                 }
2665         }
2666
2667         /**
2668          * Quotes an identifier using `backticks` or "double quotes" depending on the database type.
2669          * MySQL uses `backticks` while basically everything else uses double quotes.
2670          * Since MySQL is the odd one out here the double quotes are our generic
2671          * and we implement backticks in DatabaseMysqlBase.
2672          *
2673          * @param string $s
2674          * @return string
2675          */
2676         public function addIdentifierQuotes( $s ) {
2677                 return '"' . str_replace( '"', '""', $s ) . '"';
2678         }
2679
2680         /**
2681          * Returns if the given identifier looks quoted or not according to
2682          * the database convention for quoting identifiers .
2683          *
2684          * @note Do not use this to determine if untrusted input is safe.
2685          *   A malicious user can trick this function.
2686          * @param string $name
2687          * @return bool
2688          */
2689         public function isQuotedIdentifier( $name ) {
2690                 return $name[0] == '"' && substr( $name, -1, 1 ) == '"';
2691         }
2692
2693         /**
2694          * @param string $s
2695          * @param string $escapeChar
2696          * @return string
2697          */
2698         protected function escapeLikeInternal( $s, $escapeChar = '`' ) {
2699                 return str_replace( [ $escapeChar, '%', '_' ],
2700                         [ "{$escapeChar}{$escapeChar}", "{$escapeChar}%", "{$escapeChar}_" ],
2701                         $s );
2702         }
2703
2704         public function buildLike() {
2705                 $params = func_get_args();
2706
2707                 if ( count( $params ) > 0 && is_array( $params[0] ) ) {
2708                         $params = $params[0];
2709                 }
2710
2711                 $s = '';
2712
2713                 // We use ` instead of \ as the default LIKE escape character, since addQuotes()
2714                 // may escape backslashes, creating problems of double escaping. The `
2715                 // character has good cross-DBMS compatibility, avoiding special operators
2716                 // in MS SQL like ^ and %
2717                 $escapeChar = '`';
2718
2719                 foreach ( $params as $value ) {
2720                         if ( $value instanceof LikeMatch ) {
2721                                 $s .= $value->toString();
2722                         } else {
2723                                 $s .= $this->escapeLikeInternal( $value, $escapeChar );
2724                         }
2725                 }
2726
2727                 return ' LIKE ' .
2728                         $this->addQuotes( $s ) . ' ESCAPE ' . $this->addQuotes( $escapeChar ) . ' ';
2729         }
2730
2731         public function anyChar() {
2732                 return new LikeMatch( '_' );
2733         }
2734
2735         public function anyString() {
2736                 return new LikeMatch( '%' );
2737         }
2738
2739         public function nextSequenceValue( $seqName ) {
2740                 return null;
2741         }
2742
2743         /**
2744          * USE INDEX clause. Unlikely to be useful for anything but MySQL. This
2745          * is only needed because a) MySQL must be as efficient as possible due to
2746          * its use on Wikipedia, and b) MySQL 4.0 is kind of dumb sometimes about
2747          * which index to pick. Anyway, other databases might have different
2748          * indexes on a given table. So don't bother overriding this unless you're
2749          * MySQL.
2750          * @param string $index
2751          * @return string
2752          */
2753         public function useIndexClause( $index ) {
2754                 return '';
2755         }
2756
2757         /**
2758          * IGNORE INDEX clause. Unlikely to be useful for anything but MySQL. This
2759          * is only needed because a) MySQL must be as efficient as possible due to
2760          * its use on Wikipedia, and b) MySQL 4.0 is kind of dumb sometimes about
2761          * which index to pick. Anyway, other databases might have different
2762          * indexes on a given table. So don't bother overriding this unless you're
2763          * MySQL.
2764          * @param string $index
2765          * @return string
2766          */
2767         public function ignoreIndexClause( $index ) {
2768                 return '';
2769         }
2770
2771         public function replace( $table, $uniqueIndexes, $rows, $fname = __METHOD__ ) {
2772                 if ( count( $rows ) == 0 ) {
2773                         return;
2774                 }
2775
2776                 // Single row case
2777                 if ( !is_array( reset( $rows ) ) ) {
2778                         $rows = [ $rows ];
2779                 }
2780
2781                 try {
2782                         $this->startAtomic( $fname, self::ATOMIC_CANCELABLE );
2783                         $affectedRowCount = 0;
2784                         foreach ( $rows as $row ) {
2785                                 // Delete rows which collide with this one
2786                                 $indexWhereClauses = [];
2787                                 foreach ( $uniqueIndexes as $index ) {
2788                                         $indexColumns = (array)$index;
2789                                         $indexRowValues = array_intersect_key( $row, array_flip( $indexColumns ) );
2790                                         if ( count( $indexRowValues ) != count( $indexColumns ) ) {
2791                                                 throw new DBUnexpectedError(
2792                                                         $this,
2793                                                         'New record does not provide all values for unique key (' .
2794                                                         implode( ', ', $indexColumns ) . ')'
2795                                                 );
2796                                         } elseif ( in_array( null, $indexRowValues, true ) ) {
2797                                                 throw new DBUnexpectedError(
2798                                                         $this,
2799                                                         'New record has a null value for unique key (' .
2800                                                         implode( ', ', $indexColumns ) . ')'
2801                                                 );
2802                                         }
2803                                         $indexWhereClauses[] = $this->makeList( $indexRowValues, LIST_AND );
2804                                 }
2805
2806                                 if ( $indexWhereClauses ) {
2807                                         $this->delete( $table, $this->makeList( $indexWhereClauses, LIST_OR ), $fname );
2808                                         $affectedRowCount += $this->affectedRows();
2809                                 }
2810
2811                                 // Now insert the row
2812                                 $this->insert( $table, $row, $fname );
2813                                 $affectedRowCount += $this->affectedRows();
2814                         }
2815                         $this->endAtomic( $fname );
2816                         $this->affectedRowCount = $affectedRowCount;
2817                 } catch ( Exception $e ) {
2818                         $this->cancelAtomic( $fname );
2819                         throw $e;
2820                 }
2821         }
2822
2823         /**
2824          * REPLACE query wrapper for MySQL and SQLite, which have a native REPLACE
2825          * statement.
2826          *
2827          * @param string $table Table name
2828          * @param array|string $rows Row(s) to insert
2829          * @param string $fname Caller function name
2830          */
2831         protected function nativeReplace( $table, $rows, $fname ) {
2832                 $table = $this->tableName( $table );
2833
2834                 # Single row case
2835                 if ( !is_array( reset( $rows ) ) ) {
2836                         $rows = [ $rows ];
2837                 }
2838
2839                 $sql = "REPLACE INTO $table (" . implode( ',', array_keys( $rows[0] ) ) . ') VALUES ';
2840                 $first = true;
2841
2842                 foreach ( $rows as $row ) {
2843                         if ( $first ) {
2844                                 $first = false;
2845                         } else {
2846                                 $sql .= ',';
2847                         }
2848
2849                         $sql .= '(' . $this->makeList( $row ) . ')';
2850                 }
2851
2852                 $this->query( $sql, $fname );
2853         }
2854
2855         public function upsert( $table, array $rows, array $uniqueIndexes, array $set,
2856                 $fname = __METHOD__
2857         ) {
2858                 if ( !count( $rows ) ) {
2859                         return true; // nothing to do
2860                 }
2861
2862                 if ( !is_array( reset( $rows ) ) ) {
2863                         $rows = [ $rows ];
2864                 }
2865
2866                 if ( count( $uniqueIndexes ) ) {
2867                         $clauses = []; // list WHERE clauses that each identify a single row
2868                         foreach ( $rows as $row ) {
2869                                 foreach ( $uniqueIndexes as $index ) {
2870                                         $index = is_array( $index ) ? $index : [ $index ]; // columns
2871                                         $rowKey = []; // unique key to this row
2872                                         foreach ( $index as $column ) {
2873                                                 $rowKey[$column] = $row[$column];
2874                                         }
2875                                         $clauses[] = $this->makeList( $rowKey, self::LIST_AND );
2876                                 }
2877                         }
2878                         $where = [ $this->makeList( $clauses, self::LIST_OR ) ];
2879                 } else {
2880                         $where = false;
2881                 }
2882
2883                 $affectedRowCount = 0;
2884                 try {
2885                         $this->startAtomic( $fname, self::ATOMIC_CANCELABLE );
2886                         # Update any existing conflicting row(s)
2887                         if ( $where !== false ) {
2888                                 $this->update( $table, $set, $where, $fname );
2889                                 $affectedRowCount += $this->affectedRows();
2890                         }
2891                         # Now insert any non-conflicting row(s)
2892                         $this->insert( $table, $rows, $fname, [ 'IGNORE' ] );
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 true;
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                 $this->query( $sql, $fname );
2955
2956                 return true;
2957         }
2958
2959         final public function insertSelect(
2960                 $destTable, $srcTable, $varMap, $conds,
2961                 $fname = __METHOD__, $insertOptions = [], $selectOptions = [], $selectJoinConds = []
2962         ) {
2963                 static $hints = [ 'NO_AUTO_COLUMNS' ];
2964
2965                 $insertOptions = (array)$insertOptions;
2966                 $selectOptions = (array)$selectOptions;
2967
2968                 if ( $this->cliMode && $this->isInsertSelectSafe( $insertOptions, $selectOptions ) ) {
2969                         // For massive migrations with downtime, we don't want to select everything
2970                         // into memory and OOM, so do all this native on the server side if possible.
2971                         $this->nativeInsertSelect(
2972                                 $destTable,
2973                                 $srcTable,
2974                                 $varMap,
2975                                 $conds,
2976                                 $fname,
2977                                 array_diff( $insertOptions, $hints ),
2978                                 $selectOptions,
2979                                 $selectJoinConds
2980                         );
2981                 } else {
2982                         $this->nonNativeInsertSelect(
2983                                 $destTable,
2984                                 $srcTable,
2985                                 $varMap,
2986                                 $conds,
2987                                 $fname,
2988                                 array_diff( $insertOptions, $hints ),
2989                                 $selectOptions,
2990                                 $selectJoinConds
2991                         );
2992                 }
2993
2994                 return true;
2995         }
2996
2997         /**
2998          * @param array $insertOptions INSERT options
2999          * @param array $selectOptions SELECT options
3000          * @return bool Whether an INSERT SELECT with these options will be replication safe
3001          * @since 1.31
3002          */
3003         protected function isInsertSelectSafe( array $insertOptions, array $selectOptions ) {
3004                 return true;
3005         }
3006
3007         /**
3008          * Implementation of insertSelect() based on select() and insert()
3009          *
3010          * @see IDatabase::insertSelect()
3011          * @since 1.30
3012          * @param string $destTable
3013          * @param string|array $srcTable
3014          * @param array $varMap
3015          * @param array $conds
3016          * @param string $fname
3017          * @param array $insertOptions
3018          * @param array $selectOptions
3019          * @param array $selectJoinConds
3020          */
3021         protected function nonNativeInsertSelect( $destTable, $srcTable, $varMap, $conds,
3022                 $fname = __METHOD__,
3023                 $insertOptions = [], $selectOptions = [], $selectJoinConds = []
3024         ) {
3025                 // For web requests, do a locking SELECT and then INSERT. This puts the SELECT burden
3026                 // on only the master (without needing row-based-replication). It also makes it easy to
3027                 // know how big the INSERT is going to be.
3028                 $fields = [];
3029                 foreach ( $varMap as $dstColumn => $sourceColumnOrSql ) {
3030                         $fields[] = $this->fieldNameWithAlias( $sourceColumnOrSql, $dstColumn );
3031                 }
3032                 $selectOptions[] = 'FOR UPDATE';
3033                 $res = $this->select(
3034                         $srcTable, implode( ',', $fields ), $conds, $fname, $selectOptions, $selectJoinConds
3035                 );
3036                 if ( !$res ) {
3037                         return;
3038                 }
3039
3040                 try {
3041                         $affectedRowCount = 0;
3042                         $this->startAtomic( $fname, self::ATOMIC_CANCELABLE );
3043                         $rows = [];
3044                         $ok = true;
3045                         foreach ( $res as $row ) {
3046                                 $rows[] = (array)$row;
3047
3048                                 // Avoid inserts that are too huge
3049                                 if ( count( $rows ) >= $this->nonNativeInsertSelectBatchSize ) {
3050                                         $ok = $this->insert( $destTable, $rows, $fname, $insertOptions );
3051                                         if ( !$ok ) {
3052                                                 break;
3053                                         }
3054                                         $affectedRowCount += $this->affectedRows();
3055                                         $rows = [];
3056                                 }
3057                         }
3058                         if ( $rows && $ok ) {
3059                                 $ok = $this->insert( $destTable, $rows, $fname, $insertOptions );
3060                                 if ( $ok ) {
3061                                         $affectedRowCount += $this->affectedRows();
3062                                 }
3063                         }
3064                         if ( $ok ) {
3065                                 $this->endAtomic( $fname );
3066                                 $this->affectedRowCount = $affectedRowCount;
3067                         } else {
3068                                 $this->cancelAtomic( $fname );
3069                         }
3070                 } catch ( Exception $e ) {
3071                         $this->cancelAtomic( $fname );
3072                         throw $e;
3073                 }
3074         }
3075
3076         /**
3077          * Native server-side implementation of insertSelect() for situations where
3078          * we don't want to select everything into memory
3079          *
3080          * @see IDatabase::insertSelect()
3081          * @param string $destTable
3082          * @param string|array $srcTable
3083          * @param array $varMap
3084          * @param array $conds
3085          * @param string $fname
3086          * @param array $insertOptions
3087          * @param array $selectOptions
3088          * @param array $selectJoinConds
3089          */
3090         protected function nativeInsertSelect( $destTable, $srcTable, $varMap, $conds,
3091                 $fname = __METHOD__,
3092                 $insertOptions = [], $selectOptions = [], $selectJoinConds = []
3093         ) {
3094                 $destTable = $this->tableName( $destTable );
3095
3096                 if ( !is_array( $insertOptions ) ) {
3097                         $insertOptions = [ $insertOptions ];
3098                 }
3099
3100                 $insertOptions = $this->makeInsertOptions( $insertOptions );
3101
3102                 $selectSql = $this->selectSQLText(
3103                         $srcTable,
3104                         array_values( $varMap ),
3105                         $conds,
3106                         $fname,
3107                         $selectOptions,
3108                         $selectJoinConds
3109                 );
3110
3111                 $sql = "INSERT $insertOptions" .
3112                         " INTO $destTable (" . implode( ',', array_keys( $varMap ) ) . ') ' .
3113                         $selectSql;
3114
3115                 $this->query( $sql, $fname );
3116         }
3117
3118         /**
3119          * Construct a LIMIT query with optional offset. This is used for query
3120          * pages. The SQL should be adjusted so that only the first $limit rows
3121          * are returned. If $offset is provided as well, then the first $offset
3122          * rows should be discarded, and the next $limit rows should be returned.
3123          * If the result of the query is not ordered, then the rows to be returned
3124          * are theoretically arbitrary.
3125          *
3126          * $sql is expected to be a SELECT, if that makes a difference.
3127          *
3128          * The version provided by default works in MySQL and SQLite. It will very
3129          * likely need to be overridden for most other DBMSes.
3130          *
3131          * @param string $sql SQL query we will append the limit too
3132          * @param int $limit The SQL limit
3133          * @param int|bool $offset The SQL offset (default false)
3134          * @throws DBUnexpectedError
3135          * @return string
3136          */
3137         public function limitResult( $sql, $limit, $offset = false ) {
3138                 if ( !is_numeric( $limit ) ) {
3139                         throw new DBUnexpectedError( $this,
3140                                 "Invalid non-numeric limit passed to limitResult()\n" );
3141                 }
3142
3143                 return "$sql LIMIT "
3144                 . ( ( is_numeric( $offset ) && $offset != 0 ) ? "{$offset}," : "" )
3145                 . "{$limit} ";
3146         }
3147
3148         public function unionSupportsOrderAndLimit() {
3149                 return true; // True for almost every DB supported
3150         }
3151
3152         public function unionQueries( $sqls, $all ) {
3153                 $glue = $all ? ') UNION ALL (' : ') UNION (';
3154
3155                 return '(' . implode( $glue, $sqls ) . ')';
3156         }
3157
3158         public function unionConditionPermutations(
3159                 $table, $vars, array $permute_conds, $extra_conds = '', $fname = __METHOD__,
3160                 $options = [], $join_conds = []
3161         ) {
3162                 // First, build the Cartesian product of $permute_conds
3163                 $conds = [ [] ];
3164                 foreach ( $permute_conds as $field => $values ) {
3165                         if ( !$values ) {
3166                                 // Skip empty $values
3167                                 continue;
3168                         }
3169                         $values = array_unique( $values ); // For sanity
3170                         $newConds = [];
3171                         foreach ( $conds as $cond ) {
3172                                 foreach ( $values as $value ) {
3173                                         $cond[$field] = $value;
3174                                         $newConds[] = $cond; // Arrays are by-value, not by-reference, so this works
3175                                 }
3176                         }
3177                         $conds = $newConds;
3178                 }
3179
3180                 $extra_conds = $extra_conds === '' ? [] : (array)$extra_conds;
3181
3182                 // If there's just one condition and no subordering, hand off to
3183                 // selectSQLText directly.
3184                 if ( count( $conds ) === 1 &&
3185                         ( !isset( $options['INNER ORDER BY'] ) || !$this->unionSupportsOrderAndLimit() )
3186                 ) {
3187                         return $this->selectSQLText(
3188                                 $table, $vars, $conds[0] + $extra_conds, $fname, $options, $join_conds
3189                         );
3190                 }
3191
3192                 // Otherwise, we need to pull out the order and limit to apply after
3193                 // the union. Then build the SQL queries for each set of conditions in
3194                 // $conds. Then union them together (using UNION ALL, because the
3195                 // product *should* already be distinct).
3196                 $orderBy = $this->makeOrderBy( $options );
3197                 $limit = $options['LIMIT'] ?? null;
3198                 $offset = $options['OFFSET'] ?? false;
3199                 $all = empty( $options['NOTALL'] ) && !in_array( 'NOTALL', $options );
3200                 if ( !$this->unionSupportsOrderAndLimit() ) {
3201                         unset( $options['ORDER BY'], $options['LIMIT'], $options['OFFSET'] );
3202                 } else {
3203                         if ( array_key_exists( 'INNER ORDER BY', $options ) ) {
3204                                 $options['ORDER BY'] = $options['INNER ORDER BY'];
3205                         }
3206                         if ( $limit !== null && is_numeric( $offset ) && $offset != 0 ) {
3207                                 // We need to increase the limit by the offset rather than
3208                                 // using the offset directly, otherwise it'll skip incorrectly
3209                                 // in the subqueries.
3210                                 $options['LIMIT'] = $limit + $offset;
3211                                 unset( $options['OFFSET'] );
3212                         }
3213                 }
3214
3215                 $sqls = [];
3216                 foreach ( $conds as $cond ) {
3217                         $sqls[] = $this->selectSQLText(
3218                                 $table, $vars, $cond + $extra_conds, $fname, $options, $join_conds
3219                         );
3220                 }
3221                 $sql = $this->unionQueries( $sqls, $all ) . $orderBy;
3222                 if ( $limit !== null ) {
3223                         $sql = $this->limitResult( $sql, $limit, $offset );
3224                 }
3225
3226                 return $sql;
3227         }
3228
3229         public function conditional( $cond, $trueVal, $falseVal ) {
3230                 if ( is_array( $cond ) ) {
3231                         $cond = $this->makeList( $cond, self::LIST_AND );
3232                 }
3233
3234                 return " (CASE WHEN $cond THEN $trueVal ELSE $falseVal END) ";
3235         }
3236
3237         public function strreplace( $orig, $old, $new ) {
3238                 return "REPLACE({$orig}, {$old}, {$new})";
3239         }
3240
3241         public function getServerUptime() {
3242                 return 0;
3243         }
3244
3245         public function wasDeadlock() {
3246                 return false;
3247         }
3248
3249         public function wasLockTimeout() {
3250                 return false;
3251         }
3252
3253         public function wasConnectionLoss() {
3254                 return $this->wasConnectionError( $this->lastErrno() );
3255         }
3256
3257         public function wasReadOnlyError() {
3258                 return false;
3259         }
3260
3261         public function wasErrorReissuable() {
3262                 return (
3263                         $this->wasDeadlock() ||
3264                         $this->wasLockTimeout() ||
3265                         $this->wasConnectionLoss()
3266                 );
3267         }
3268
3269         /**
3270          * Do not use this method outside of Database/DBError classes
3271          *
3272          * @param int|string $errno
3273          * @return bool Whether the given query error was a connection drop
3274          */
3275         public function wasConnectionError( $errno ) {
3276                 return false;
3277         }
3278
3279         /**
3280          * @return bool Whether it is safe to assume the given error only caused statement rollback
3281          * @note This is for backwards compatibility for callers catching DBError exceptions in
3282          *   order to ignore problems like duplicate key errors or foriegn key violations
3283          * @since 1.31
3284          */
3285         protected function wasKnownStatementRollbackError() {
3286                 return false; // don't know; it could have caused a transaction rollback
3287         }
3288
3289         public function deadlockLoop() {
3290                 $args = func_get_args();
3291                 $function = array_shift( $args );
3292                 $tries = self::DEADLOCK_TRIES;
3293
3294                 $this->begin( __METHOD__ );
3295
3296                 $retVal = null;
3297                 /** @var Exception $e */
3298                 $e = null;
3299                 do {
3300                         try {
3301                                 $retVal = $function( ...$args );
3302                                 break;
3303                         } catch ( DBQueryError $e ) {
3304                                 if ( $this->wasDeadlock() ) {
3305                                         // Retry after a randomized delay
3306                                         usleep( mt_rand( self::DEADLOCK_DELAY_MIN, self::DEADLOCK_DELAY_MAX ) );
3307                                 } else {
3308                                         // Throw the error back up
3309                                         throw $e;
3310                                 }
3311                         }
3312                 } while ( --$tries > 0 );
3313
3314                 if ( $tries <= 0 ) {
3315                         // Too many deadlocks; give up
3316                         $this->rollback( __METHOD__ );
3317                         throw $e;
3318                 } else {
3319                         $this->commit( __METHOD__ );
3320
3321                         return $retVal;
3322                 }
3323         }
3324
3325         public function masterPosWait( DBMasterPos $pos, $timeout ) {
3326                 # Real waits are implemented in the subclass.
3327                 return 0;
3328         }
3329
3330         public function getReplicaPos() {
3331                 # Stub
3332                 return false;
3333         }
3334
3335         public function getMasterPos() {
3336                 # Stub
3337                 return false;
3338         }
3339
3340         public function serverIsReadOnly() {
3341                 return false;
3342         }
3343
3344         final public function onTransactionResolution( callable $callback, $fname = __METHOD__ ) {
3345                 if ( !$this->trxLevel ) {
3346                         throw new DBUnexpectedError( $this, "No transaction is active." );
3347                 }
3348                 $this->trxEndCallbacks[] = [ $callback, $fname, $this->currentAtomicSectionId() ];
3349         }
3350
3351         final public function onTransactionCommitOrIdle( callable $callback, $fname = __METHOD__ ) {
3352                 if ( !$this->trxLevel && $this->getTransactionRoundId() ) {
3353                         // Start an implicit transaction similar to how query() does
3354                         $this->begin( __METHOD__, self::TRANSACTION_INTERNAL );
3355                         $this->trxAutomatic = true;
3356                 }
3357
3358                 $this->trxIdleCallbacks[] = [ $callback, $fname, $this->currentAtomicSectionId() ];
3359                 if ( !$this->trxLevel ) {
3360                         $this->runOnTransactionIdleCallbacks( self::TRIGGER_IDLE );
3361                 }
3362         }
3363
3364         final public function onTransactionIdle( callable $callback, $fname = __METHOD__ ) {
3365                 $this->onTransactionCommitOrIdle( $callback, $fname );
3366         }
3367
3368         final public function onTransactionPreCommitOrIdle( callable $callback, $fname = __METHOD__ ) {
3369                 if ( !$this->trxLevel && $this->getTransactionRoundId() ) {
3370                         // Start an implicit transaction similar to how query() does
3371                         $this->begin( __METHOD__, self::TRANSACTION_INTERNAL );
3372                         $this->trxAutomatic = true;
3373                 }
3374
3375                 if ( $this->trxLevel ) {
3376                         $this->trxPreCommitCallbacks[] = [ $callback, $fname, $this->currentAtomicSectionId() ];
3377                 } else {
3378                         // No transaction is active nor will start implicitly, so make one for this callback
3379                         $this->startAtomic( __METHOD__, self::ATOMIC_CANCELABLE );
3380                         try {
3381                                 $callback( $this );
3382                                 $this->endAtomic( __METHOD__ );
3383                         } catch ( Exception $e ) {
3384                                 $this->cancelAtomic( __METHOD__ );
3385                                 throw $e;
3386                         }
3387                 }
3388         }
3389
3390         /**
3391          * @return AtomicSectionIdentifier|null ID of the topmost atomic section level
3392          */
3393         private function currentAtomicSectionId() {
3394                 if ( $this->trxLevel && $this->trxAtomicLevels ) {
3395                         $levelInfo = end( $this->trxAtomicLevels );
3396
3397                         return $levelInfo[1];
3398                 }
3399
3400                 return null;
3401         }
3402
3403         /**
3404          * @param AtomicSectionIdentifier $old
3405          * @param AtomicSectionIdentifier $new
3406          */
3407         private function reassignCallbacksForSection(
3408                 AtomicSectionIdentifier $old, AtomicSectionIdentifier $new
3409         ) {
3410                 foreach ( $this->trxPreCommitCallbacks as $key => $info ) {
3411                         if ( $info[2] === $old ) {
3412                                 $this->trxPreCommitCallbacks[$key][2] = $new;
3413                         }
3414                 }
3415                 foreach ( $this->trxIdleCallbacks as $key => $info ) {
3416                         if ( $info[2] === $old ) {
3417                                 $this->trxIdleCallbacks[$key][2] = $new;
3418                         }
3419                 }
3420                 foreach ( $this->trxEndCallbacks as $key => $info ) {
3421                         if ( $info[2] === $old ) {
3422                                 $this->trxEndCallbacks[$key][2] = $new;
3423                         }
3424                 }
3425         }
3426
3427         /**
3428          * @param AtomicSectionIdentifier[] $sectionIds ID of an actual savepoint
3429          * @throws UnexpectedValueException
3430          */
3431         private function modifyCallbacksForCancel( array $sectionIds ) {
3432                 // Cancel the "on commit" callbacks owned by this savepoint
3433                 $this->trxIdleCallbacks = array_filter(
3434                         $this->trxIdleCallbacks,
3435                         function ( $entry ) use ( $sectionIds ) {
3436                                 return !in_array( $entry[2], $sectionIds, true );
3437                         }
3438                 );
3439                 $this->trxPreCommitCallbacks = array_filter(
3440                         $this->trxPreCommitCallbacks,
3441                         function ( $entry ) use ( $sectionIds ) {
3442                                 return !in_array( $entry[2], $sectionIds, true );
3443                         }
3444                 );
3445                 // Make "on resolution" callbacks owned by this savepoint to perceive a rollback
3446                 foreach ( $this->trxEndCallbacks as $key => $entry ) {
3447                         if ( in_array( $entry[2], $sectionIds, true ) ) {
3448                                 $callback = $entry[0];
3449                                 $this->trxEndCallbacks[$key][0] = function () use ( $callback ) {
3450                                         return $callback( self::TRIGGER_ROLLBACK, $this );
3451                                 };
3452                         }
3453                 }
3454         }
3455
3456         final public function setTransactionListener( $name, callable $callback = null ) {
3457                 if ( $callback ) {
3458                         $this->trxRecurringCallbacks[$name] = $callback;
3459                 } else {
3460                         unset( $this->trxRecurringCallbacks[$name] );
3461                 }
3462         }
3463
3464         /**
3465          * Whether to disable running of post-COMMIT/ROLLBACK callbacks
3466          *
3467          * This method should not be used outside of Database/LoadBalancer
3468          *
3469          * @param bool $suppress
3470          * @since 1.28
3471          */
3472         final public function setTrxEndCallbackSuppression( $suppress ) {
3473                 $this->trxEndCallbacksSuppressed = $suppress;
3474         }
3475
3476         /**
3477          * Actually consume and run any "on transaction idle/resolution" callbacks.
3478          *
3479          * This method should not be used outside of Database/LoadBalancer
3480          *
3481          * @param int $trigger IDatabase::TRIGGER_* constant
3482          * @return int Number of callbacks attempted
3483          * @since 1.20
3484          * @throws Exception
3485          */
3486         public function runOnTransactionIdleCallbacks( $trigger ) {
3487                 if ( $this->trxLevel ) { // sanity
3488                         throw new DBUnexpectedError( $this, __METHOD__ . ': a transaction is still open.' );
3489                 }
3490
3491                 if ( $this->trxEndCallbacksSuppressed ) {
3492                         return 0;
3493                 }
3494
3495                 $count = 0;
3496                 $autoTrx = $this->getFlag( self::DBO_TRX ); // automatic begin() enabled?
3497                 /** @var Exception $e */
3498                 $e = null; // first exception
3499                 do { // callbacks may add callbacks :)
3500                         $callbacks = array_merge(
3501                                 $this->trxIdleCallbacks,
3502                                 $this->trxEndCallbacks // include "transaction resolution" callbacks
3503                         );
3504                         $this->trxIdleCallbacks = []; // consumed (and recursion guard)
3505                         $this->trxEndCallbacks = []; // consumed (recursion guard)
3506                         foreach ( $callbacks as $callback ) {
3507                                 ++$count;
3508                                 list( $phpCallback ) = $callback;
3509                                 $this->clearFlag( self::DBO_TRX ); // make each query its own transaction
3510                                 try {
3511                                         call_user_func( $phpCallback, $trigger, $this );
3512                                 } catch ( Exception $ex ) {
3513                                         call_user_func( $this->errorLogger, $ex );
3514                                         $e = $e ?: $ex;
3515                                         // Some callbacks may use startAtomic/endAtomic, so make sure
3516                                         // their transactions are ended so other callbacks don't fail
3517                                         if ( $this->trxLevel() ) {
3518                                                 $this->rollback( __METHOD__, self::FLUSHING_INTERNAL );
3519                                         }
3520                                 } finally {
3521                                         if ( $autoTrx ) {
3522                                                 $this->setFlag( self::DBO_TRX ); // restore automatic begin()
3523                                         } else {
3524                                                 $this->clearFlag( self::DBO_TRX ); // restore auto-commit
3525                                         }
3526                                 }
3527                         }
3528                 } while ( count( $this->trxIdleCallbacks ) );
3529
3530                 if ( $e instanceof Exception ) {
3531                         throw $e; // re-throw any first exception
3532                 }
3533
3534                 return $count;
3535         }
3536
3537         /**
3538          * Actually consume and run any "on transaction pre-commit" callbacks.
3539          *
3540          * This method should not be used outside of Database/LoadBalancer
3541          *
3542          * @since 1.22
3543          * @return int Number of callbacks attempted
3544          * @throws Exception
3545          */
3546         public function runOnTransactionPreCommitCallbacks() {
3547                 $count = 0;
3548
3549                 $e = null; // first exception
3550                 do { // callbacks may add callbacks :)
3551                         $callbacks = $this->trxPreCommitCallbacks;
3552                         $this->trxPreCommitCallbacks = []; // consumed (and recursion guard)
3553                         foreach ( $callbacks as $callback ) {
3554                                 try {
3555                                         ++$count;
3556                                         list( $phpCallback ) = $callback;
3557                                         $phpCallback( $this );
3558                                 } catch ( Exception $ex ) {
3559                                         ( $this->errorLogger )( $ex );
3560                                         $e = $e ?: $ex;
3561                                 }
3562                         }
3563                 } while ( count( $this->trxPreCommitCallbacks ) );
3564
3565                 if ( $e instanceof Exception ) {
3566                         throw $e; // re-throw any first exception
3567                 }
3568
3569                 return $count;
3570         }
3571
3572         /**
3573          * Actually run any "transaction listener" callbacks.
3574          *
3575          * This method should not be used outside of Database/LoadBalancer
3576          *
3577          * @param int $trigger IDatabase::TRIGGER_* constant
3578          * @throws Exception
3579          * @since 1.20
3580          */
3581         public function runTransactionListenerCallbacks( $trigger ) {
3582                 if ( $this->trxEndCallbacksSuppressed ) {
3583                         return;
3584                 }
3585
3586                 /** @var Exception $e */
3587                 $e = null; // first exception
3588
3589                 foreach ( $this->trxRecurringCallbacks as $phpCallback ) {
3590                         try {
3591                                 $phpCallback( $trigger, $this );
3592                         } catch ( Exception $ex ) {
3593                                 ( $this->errorLogger )( $ex );
3594                                 $e = $e ?: $ex;
3595                         }
3596                 }
3597
3598                 if ( $e instanceof Exception ) {
3599                         throw $e; // re-throw any first exception
3600                 }
3601         }
3602
3603         /**
3604          * Create a savepoint
3605          *
3606          * This is used internally to implement atomic sections. It should not be
3607          * used otherwise.
3608          *
3609          * @since 1.31
3610          * @param string $identifier Identifier for the savepoint
3611          * @param string $fname Calling function name
3612          */
3613         protected function doSavepoint( $identifier, $fname ) {
3614                 $this->query( 'SAVEPOINT ' . $this->addIdentifierQuotes( $identifier ), $fname );
3615         }
3616
3617         /**
3618          * Release a savepoint
3619          *
3620          * This is used internally to implement atomic sections. It should not be
3621          * used otherwise.
3622          *
3623          * @since 1.31
3624          * @param string $identifier Identifier for the savepoint
3625          * @param string $fname Calling function name
3626          */
3627         protected function doReleaseSavepoint( $identifier, $fname ) {
3628                 $this->query( 'RELEASE SAVEPOINT ' . $this->addIdentifierQuotes( $identifier ), $fname );
3629         }
3630
3631         /**
3632          * Rollback to a savepoint
3633          *
3634          * This is used internally to implement atomic sections. It should not be
3635          * used otherwise.
3636          *
3637          * @since 1.31
3638          * @param string $identifier Identifier for the savepoint
3639          * @param string $fname Calling function name
3640          */
3641         protected function doRollbackToSavepoint( $identifier, $fname ) {
3642                 $this->query( 'ROLLBACK TO SAVEPOINT ' . $this->addIdentifierQuotes( $identifier ), $fname );
3643         }
3644
3645         /**
3646          * @param string $fname
3647          * @return string
3648          */
3649         private function nextSavepointId( $fname ) {
3650                 $savepointId = self::$SAVEPOINT_PREFIX . ++$this->trxAtomicCounter;
3651                 if ( strlen( $savepointId ) > 30 ) {
3652                         // 30 == Oracle's identifier length limit (pre 12c)
3653                         // With a 22 character prefix, that puts the highest number at 99999999.
3654                         throw new DBUnexpectedError(
3655                                 $this,
3656                                 'There have been an excessively large number of atomic sections in a transaction'
3657                                 . " started by $this->trxFname (at $fname)"
3658                         );
3659                 }
3660
3661                 return $savepointId;
3662         }
3663
3664         final public function startAtomic(
3665                 $fname = __METHOD__, $cancelable = self::ATOMIC_NOT_CANCELABLE
3666         ) {
3667                 $savepointId = $cancelable === self::ATOMIC_CANCELABLE ? self::$NOT_APPLICABLE : null;
3668
3669                 if ( !$this->trxLevel ) {
3670                         $this->begin( $fname, self::TRANSACTION_INTERNAL ); // sets trxAutomatic
3671                         // If DBO_TRX is set, a series of startAtomic/endAtomic pairs will result
3672                         // in all changes being in one transaction to keep requests transactional.
3673                         if ( $this->getFlag( self::DBO_TRX ) ) {
3674                                 // Since writes could happen in between the topmost atomic sections as part
3675                                 // of the transaction, those sections will need savepoints.
3676                                 $savepointId = $this->nextSavepointId( $fname );
3677                                 $this->doSavepoint( $savepointId, $fname );
3678                         } else {
3679                                 $this->trxAutomaticAtomic = true;
3680                         }
3681                 } elseif ( $cancelable === self::ATOMIC_CANCELABLE ) {
3682                         $savepointId = $this->nextSavepointId( $fname );
3683                         $this->doSavepoint( $savepointId, $fname );
3684                 }
3685
3686                 $sectionId = new AtomicSectionIdentifier;
3687                 $this->trxAtomicLevels[] = [ $fname, $sectionId, $savepointId ];
3688                 $this->queryLogger->debug( 'startAtomic: entering level ' .
3689                         ( count( $this->trxAtomicLevels ) - 1 ) . " ($fname)" );
3690
3691                 return $sectionId;
3692         }
3693
3694         final public function endAtomic( $fname = __METHOD__ ) {
3695                 if ( !$this->trxLevel || !$this->trxAtomicLevels ) {
3696                         throw new DBUnexpectedError( $this, "No atomic section is open (got $fname)." );
3697                 }
3698
3699                 // Check if the current section matches $fname
3700                 $pos = count( $this->trxAtomicLevels ) - 1;
3701                 list( $savedFname, $sectionId, $savepointId ) = $this->trxAtomicLevels[$pos];
3702                 $this->queryLogger->debug( "endAtomic: leaving level $pos ($fname)" );
3703
3704                 if ( $savedFname !== $fname ) {
3705                         throw new DBUnexpectedError(
3706                                 $this,
3707                                 "Invalid atomic section ended (got $fname but expected $savedFname)."
3708                         );
3709                 }
3710
3711                 // Remove the last section (no need to re-index the array)
3712                 array_pop( $this->trxAtomicLevels );
3713
3714                 if ( !$this->trxAtomicLevels && $this->trxAutomaticAtomic ) {
3715                         $this->commit( $fname, self::FLUSHING_INTERNAL );
3716                 } elseif ( $savepointId !== null && $savepointId !== self::$NOT_APPLICABLE ) {
3717                         $this->doReleaseSavepoint( $savepointId, $fname );
3718                 }
3719
3720                 // Hoist callback ownership for callbacks in the section that just ended;
3721                 // all callbacks should have an owner that is present in trxAtomicLevels.
3722                 $currentSectionId = $this->currentAtomicSectionId();
3723                 if ( $currentSectionId ) {
3724                         $this->reassignCallbacksForSection( $sectionId, $currentSectionId );
3725                 }
3726         }
3727
3728         final public function cancelAtomic(
3729                 $fname = __METHOD__, AtomicSectionIdentifier $sectionId = null
3730         ) {
3731                 if ( !$this->trxLevel || !$this->trxAtomicLevels ) {
3732                         throw new DBUnexpectedError( $this, "No atomic section is open (got $fname)." );
3733                 }
3734
3735                 $excisedFnames = [];
3736                 if ( $sectionId !== null ) {
3737                         // Find the (last) section with the given $sectionId
3738                         $pos = -1;
3739                         foreach ( $this->trxAtomicLevels as $i => list( $asFname, $asId, $spId ) ) {
3740                                 if ( $asId === $sectionId ) {
3741                                         $pos = $i;
3742                                 }
3743                         }
3744                         if ( $pos < 0 ) {
3745                                 throw new DBUnexpectedError( $this, "Atomic section not found (for $fname)" );
3746                         }
3747                         // Remove all descendant sections and re-index the array
3748                         $excisedIds = [];
3749                         $len = count( $this->trxAtomicLevels );
3750                         for ( $i = $pos + 1; $i < $len; ++$i ) {
3751                                 $excisedFnames[] = $this->trxAtomicLevels[$i][0];
3752                                 $excisedIds[] = $this->trxAtomicLevels[$i][1];
3753                         }
3754                         $this->trxAtomicLevels = array_slice( $this->trxAtomicLevels, 0, $pos + 1 );
3755                         $this->modifyCallbacksForCancel( $excisedIds );
3756                 }
3757
3758                 // Check if the current section matches $fname
3759                 $pos = count( $this->trxAtomicLevels ) - 1;
3760                 list( $savedFname, $savedSectionId, $savepointId ) = $this->trxAtomicLevels[$pos];
3761
3762                 if ( $excisedFnames ) {
3763                         $this->queryLogger->debug( "cancelAtomic: canceling level $pos ($savedFname) " .
3764                                 "and descendants " . implode( ', ', $excisedFnames ) );
3765                 } else {
3766                         $this->queryLogger->debug( "cancelAtomic: canceling level $pos ($savedFname)" );
3767                 }
3768
3769                 if ( $savedFname !== $fname ) {
3770                         throw new DBUnexpectedError(
3771                                 $this,
3772                                 "Invalid atomic section ended (got $fname but expected $savedFname)."
3773                         );
3774                 }
3775
3776                 // Remove the last section (no need to re-index the array)
3777                 array_pop( $this->trxAtomicLevels );
3778                 $this->modifyCallbacksForCancel( [ $savedSectionId ] );
3779
3780                 if ( $savepointId !== null ) {
3781                         // Rollback the transaction to the state just before this atomic section
3782                         if ( $savepointId === self::$NOT_APPLICABLE ) {
3783                                 $this->rollback( $fname, self::FLUSHING_INTERNAL );
3784                         } else {
3785                                 $this->doRollbackToSavepoint( $savepointId, $fname );
3786                                 $this->trxStatus = self::STATUS_TRX_OK; // no exception; recovered
3787                                 $this->trxStatusIgnoredCause = null;
3788                         }
3789                 } elseif ( $this->trxStatus > self::STATUS_TRX_ERROR ) {
3790                         // Put the transaction into an error state if it's not already in one
3791                         $this->trxStatus = self::STATUS_TRX_ERROR;
3792                         $this->trxStatusCause = new DBUnexpectedError(
3793                                 $this,
3794                                 "Uncancelable atomic section canceled (got $fname)."
3795                         );
3796                 }
3797
3798                 $this->affectedRowCount = 0; // for the sake of consistency
3799         }
3800
3801         final public function doAtomicSection(
3802                 $fname, callable $callback, $cancelable = self::ATOMIC_NOT_CANCELABLE
3803         ) {
3804                 $sectionId = $this->startAtomic( $fname, $cancelable );
3805                 try {
3806                         $res = $callback( $this, $fname );
3807                 } catch ( Exception $e ) {
3808                         $this->cancelAtomic( $fname, $sectionId );
3809
3810                         throw $e;
3811                 }
3812                 $this->endAtomic( $fname );
3813
3814                 return $res;
3815         }
3816
3817         final public function begin( $fname = __METHOD__, $mode = self::TRANSACTION_EXPLICIT ) {
3818                 static $modes = [ self::TRANSACTION_EXPLICIT, self::TRANSACTION_INTERNAL ];
3819                 if ( !in_array( $mode, $modes, true ) ) {
3820                         throw new DBUnexpectedError( $this, "$fname: invalid mode parameter '$mode'." );
3821                 }
3822
3823                 // Protect against mismatched atomic section, transaction nesting, and snapshot loss
3824                 if ( $this->trxLevel ) {
3825                         if ( $this->trxAtomicLevels ) {
3826                                 $levels = $this->flatAtomicSectionList();
3827                                 $msg = "$fname: Got explicit BEGIN while atomic section(s) $levels are open.";
3828                                 throw new DBUnexpectedError( $this, $msg );
3829                         } elseif ( !$this->trxAutomatic ) {
3830                                 $msg = "$fname: Explicit transaction already active (from {$this->trxFname}).";
3831                                 throw new DBUnexpectedError( $this, $msg );
3832                         } else {
3833                                 $msg = "$fname: Implicit transaction already active (from {$this->trxFname}).";
3834                                 throw new DBUnexpectedError( $this, $msg );
3835                         }
3836                 } elseif ( $this->getFlag( self::DBO_TRX ) && $mode !== self::TRANSACTION_INTERNAL ) {
3837                         $msg = "$fname: Implicit transaction expected (DBO_TRX set).";
3838                         throw new DBUnexpectedError( $this, $msg );
3839                 }
3840
3841                 // Avoid fatals if close() was called
3842                 $this->assertOpen();
3843
3844                 $this->doBegin( $fname );
3845                 $this->trxStatus = self::STATUS_TRX_OK;
3846                 $this->trxStatusIgnoredCause = null;
3847                 $this->trxAtomicCounter = 0;
3848                 $this->trxTimestamp = microtime( true );
3849                 $this->trxFname = $fname;
3850                 $this->trxDoneWrites = false;
3851                 $this->trxAutomaticAtomic = false;
3852                 $this->trxAtomicLevels = [];
3853                 $this->trxShortId = sprintf( '%06x', mt_rand( 0, 0xffffff ) );
3854                 $this->trxWriteDuration = 0.0;
3855                 $this->trxWriteQueryCount = 0;
3856                 $this->trxWriteAffectedRows = 0;
3857                 $this->trxWriteAdjDuration = 0.0;
3858                 $this->trxWriteAdjQueryCount = 0;
3859                 $this->trxWriteCallers = [];
3860                 // First SELECT after BEGIN will establish the snapshot in REPEATABLE-READ.
3861                 // Get an estimate of the replication lag before any such queries.
3862                 $this->trxReplicaLag = null; // clear cached value first
3863                 $this->trxReplicaLag = $this->getApproximateLagStatus()['lag'];
3864                 // T147697: make explicitTrxActive() return true until begin() finishes. This way, no
3865                 // caller will think its OK to muck around with the transaction just because startAtomic()
3866                 // has not yet completed (e.g. setting trxAtomicLevels).
3867                 $this->trxAutomatic = ( $mode === self::TRANSACTION_INTERNAL );
3868         }
3869
3870         /**
3871          * Issues the BEGIN command to the database server.
3872          *
3873          * @see Database::begin()
3874          * @param string $fname
3875          */
3876         protected function doBegin( $fname ) {
3877                 $this->query( 'BEGIN', $fname );
3878                 $this->trxLevel = 1;
3879         }
3880
3881         final public function commit( $fname = __METHOD__, $flush = self::FLUSHING_ONE ) {
3882                 static $modes = [ self::FLUSHING_ONE, self::FLUSHING_ALL_PEERS, self::FLUSHING_INTERNAL ];
3883                 if ( !in_array( $flush, $modes, true ) ) {
3884                         throw new DBUnexpectedError( $this, "$fname: invalid flush parameter '$flush'." );
3885                 }
3886
3887                 if ( $this->trxLevel && $this->trxAtomicLevels ) {
3888                         // There are still atomic sections open; this cannot be ignored
3889                         $levels = $this->flatAtomicSectionList();
3890                         throw new DBUnexpectedError(
3891                                 $this,
3892                                 "$fname: Got COMMIT while atomic sections $levels are still open."
3893                         );
3894                 }
3895
3896                 if ( $flush === self::FLUSHING_INTERNAL || $flush === self::FLUSHING_ALL_PEERS ) {
3897                         if ( !$this->trxLevel ) {
3898                                 return; // nothing to do
3899                         } elseif ( !$this->trxAutomatic ) {
3900                                 throw new DBUnexpectedError(
3901                                         $this,
3902                                         "$fname: Flushing an explicit transaction, getting out of sync."
3903                                 );
3904                         }
3905                 } else {
3906                         if ( !$this->trxLevel ) {
3907                                 $this->queryLogger->error(
3908                                         "$fname: No transaction to commit, something got out of sync." );
3909                                 return; // nothing to do
3910                         } elseif ( $this->trxAutomatic ) {
3911                                 throw new DBUnexpectedError(
3912                                         $this,
3913                                         "$fname: Expected mass commit of all peer transactions (DBO_TRX set)."
3914                                 );
3915                         }
3916                 }
3917
3918                 // Avoid fatals if close() was called
3919                 $this->assertOpen();
3920
3921                 $this->runOnTransactionPreCommitCallbacks();
3922
3923                 $writeTime = $this->pendingWriteQueryDuration( self::ESTIMATE_DB_APPLY );
3924                 $this->doCommit( $fname );
3925                 $this->trxStatus = self::STATUS_TRX_NONE;
3926
3927                 if ( $this->trxDoneWrites ) {
3928                         $this->lastWriteTime = microtime( true );
3929                         $this->trxProfiler->transactionWritingOut(
3930                                 $this->server,
3931                                 $this->getDomainID(),
3932                                 $this->trxShortId,
3933                                 $writeTime,
3934                                 $this->trxWriteAffectedRows
3935                         );
3936                 }
3937
3938                 // With FLUSHING_ALL_PEERS, callbacks will be explicitly run later
3939                 if ( $flush !== self::FLUSHING_ALL_PEERS ) {
3940                         $this->runOnTransactionIdleCallbacks( self::TRIGGER_COMMIT );
3941                         $this->runTransactionListenerCallbacks( self::TRIGGER_COMMIT );
3942                 }
3943         }
3944
3945         /**
3946          * Issues the COMMIT command to the database server.
3947          *
3948          * @see Database::commit()
3949          * @param string $fname
3950          */
3951         protected function doCommit( $fname ) {
3952                 if ( $this->trxLevel ) {
3953                         $this->query( 'COMMIT', $fname );
3954                         $this->trxLevel = 0;
3955                 }
3956         }
3957
3958         final public function rollback( $fname = __METHOD__, $flush = '' ) {
3959                 $trxActive = $this->trxLevel;
3960
3961                 if ( $flush !== self::FLUSHING_INTERNAL && $flush !== self::FLUSHING_ALL_PEERS ) {
3962                         if ( $this->getFlag( self::DBO_TRX ) ) {
3963                                 throw new DBUnexpectedError(
3964                                         $this,
3965                                         "$fname: Expected mass rollback of all peer transactions (DBO_TRX set)."
3966                                 );
3967                         }
3968                 }
3969
3970                 if ( $trxActive ) {
3971                         // Avoid fatals if close() was called
3972                         $this->assertOpen();
3973
3974                         $this->doRollback( $fname );
3975                         $this->trxStatus = self::STATUS_TRX_NONE;
3976                         $this->trxAtomicLevels = [];
3977                         // Estimate the RTT via a query now that trxStatus is OK
3978                         $writeTime = $this->pingAndCalculateLastTrxApplyTime();
3979
3980                         if ( $this->trxDoneWrites ) {
3981                                 $this->trxProfiler->transactionWritingOut(
3982                                         $this->server,
3983                                         $this->getDomainID(),
3984                                         $this->trxShortId,
3985                                         $writeTime,
3986                                         $this->trxWriteAffectedRows
3987                                 );
3988                         }
3989                 }
3990
3991                 // Clear any commit-dependant callbacks. They might even be present
3992                 // only due to transaction rounds, with no SQL transaction being active
3993                 $this->trxIdleCallbacks = [];
3994                 $this->trxPreCommitCallbacks = [];
3995
3996                 // With FLUSHING_ALL_PEERS, callbacks will be explicitly run later
3997                 if ( $trxActive && $flush !== self::FLUSHING_ALL_PEERS ) {
3998                         try {
3999                                 $this->runOnTransactionIdleCallbacks( self::TRIGGER_ROLLBACK );
4000                         } catch ( Exception $e ) {
4001                                 // already logged; finish and let LoadBalancer move on during mass-rollback
4002                         }
4003                         try {
4004                                 $this->runTransactionListenerCallbacks( self::TRIGGER_ROLLBACK );
4005                         } catch ( Exception $e ) {
4006                                 // already logged; let LoadBalancer move on during mass-rollback
4007                         }
4008
4009                         $this->affectedRowCount = 0; // for the sake of consistency
4010                 }
4011         }
4012
4013         /**
4014          * Issues the ROLLBACK command to the database server.
4015          *
4016          * @see Database::rollback()
4017          * @param string $fname
4018          */
4019         protected function doRollback( $fname ) {
4020                 if ( $this->trxLevel ) {
4021                         # Disconnects cause rollback anyway, so ignore those errors
4022                         $ignoreErrors = true;
4023                         $this->query( 'ROLLBACK', $fname, $ignoreErrors );
4024                         $this->trxLevel = 0;
4025                 }
4026         }
4027
4028         public function flushSnapshot( $fname = __METHOD__ ) {
4029                 if ( $this->writesOrCallbacksPending() || $this->explicitTrxActive() ) {
4030                         // This only flushes transactions to clear snapshots, not to write data
4031                         $fnames = implode( ', ', $this->pendingWriteAndCallbackCallers() );
4032                         throw new DBUnexpectedError(
4033                                 $this,
4034                                 "$fname: Cannot flush snapshot because writes are pending ($fnames)."
4035                         );
4036                 }
4037
4038                 $this->commit( $fname, self::FLUSHING_INTERNAL );
4039         }
4040
4041         public function explicitTrxActive() {
4042                 return $this->trxLevel && ( $this->trxAtomicLevels || !$this->trxAutomatic );
4043         }
4044
4045         public function duplicateTableStructure(
4046                 $oldName, $newName, $temporary = false, $fname = __METHOD__
4047         ) {
4048                 throw new RuntimeException( __METHOD__ . ' is not implemented in descendant class' );
4049         }
4050
4051         public function listTables( $prefix = null, $fname = __METHOD__ ) {
4052                 throw new RuntimeException( __METHOD__ . ' is not implemented in descendant class' );
4053         }
4054
4055         public function listViews( $prefix = null, $fname = __METHOD__ ) {
4056                 throw new RuntimeException( __METHOD__ . ' is not implemented in descendant class' );
4057         }
4058
4059         public function timestamp( $ts = 0 ) {
4060                 $t = new ConvertibleTimestamp( $ts );
4061                 // Let errors bubble up to avoid putting garbage in the DB
4062                 return $t->getTimestamp( TS_MW );
4063         }
4064
4065         public function timestampOrNull( $ts = null ) {
4066                 if ( is_null( $ts ) ) {
4067                         return null;
4068                 } else {
4069                         return $this->timestamp( $ts );
4070                 }
4071         }
4072
4073         public function affectedRows() {
4074                 return ( $this->affectedRowCount === null )
4075                         ? $this->fetchAffectedRowCount() // default to driver value
4076                         : $this->affectedRowCount;
4077         }
4078
4079         /**
4080          * @return int Number of retrieved rows according to the driver
4081          */
4082         abstract protected function fetchAffectedRowCount();
4083
4084         /**
4085          * Take the result from a query, and wrap it in a ResultWrapper if
4086          * necessary. Boolean values are passed through as is, to indicate success
4087          * of write queries or failure.
4088          *
4089          * Once upon a time, Database::query() returned a bare MySQL result
4090          * resource, and it was necessary to call this function to convert it to
4091          * a wrapper. Nowadays, raw database objects are never exposed to external
4092          * callers, so this is unnecessary in external code.
4093          *
4094          * @param bool|ResultWrapper|resource $result
4095          * @return bool|ResultWrapper
4096          */
4097         protected function resultObject( $result ) {
4098                 if ( !$result ) {
4099                         return false;
4100                 } elseif ( $result instanceof ResultWrapper ) {
4101                         return $result;
4102                 } elseif ( $result === true ) {
4103                         // Successful write query
4104                         return $result;
4105                 } else {
4106                         return new ResultWrapper( $this, $result );
4107                 }
4108         }
4109
4110         public function ping( &$rtt = null ) {
4111                 // Avoid hitting the server if it was hit recently
4112                 if ( $this->isOpen() && ( microtime( true ) - $this->lastPing ) < self::PING_TTL ) {
4113                         if ( !func_num_args() || $this->rttEstimate > 0 ) {
4114                                 $rtt = $this->rttEstimate;
4115                                 return true; // don't care about $rtt
4116                         }
4117                 }
4118
4119                 // This will reconnect if possible or return false if not
4120                 $this->clearFlag( self::DBO_TRX, self::REMEMBER_PRIOR );
4121                 $ok = ( $this->query( self::PING_QUERY, __METHOD__, true ) !== false );
4122                 $this->restoreFlags( self::RESTORE_PRIOR );
4123
4124                 if ( $ok ) {
4125                         $rtt = $this->rttEstimate;
4126                 }
4127
4128                 return $ok;
4129         }
4130
4131         /**
4132          * Close any existing (dead) database connection and open a new connection
4133          *
4134          * @param string $fname
4135          * @return bool True if new connection is opened successfully, false if error
4136          */
4137         protected function replaceLostConnection( $fname ) {
4138                 $this->closeConnection();
4139                 $this->opened = false;
4140                 $this->conn = false;
4141                 try {
4142                         $this->open(
4143                                 $this->server,
4144                                 $this->user,
4145                                 $this->password,
4146                                 $this->getDBname(),
4147                                 $this->dbSchema(),
4148                                 $this->tablePrefix()
4149                         );
4150                         $this->lastPing = microtime( true );
4151                         $ok = true;
4152
4153                         $this->connLogger->warning(
4154                                 $fname . ': lost connection to {dbserver}; reconnected',
4155                                 [
4156                                         'dbserver' => $this->getServer(),
4157                                         'trace' => ( new RuntimeException() )->getTraceAsString()
4158                                 ]
4159                         );
4160                 } catch ( DBConnectionError $e ) {
4161                         $ok = false;
4162
4163                         $this->connLogger->error(
4164                                 $fname . ': lost connection to {dbserver} permanently',
4165                                 [ 'dbserver' => $this->getServer() ]
4166                         );
4167                 }
4168
4169                 $this->handleSessionLoss();
4170
4171                 return $ok;
4172         }
4173
4174         public function getSessionLagStatus() {
4175                 return $this->getRecordedTransactionLagStatus() ?: $this->getApproximateLagStatus();
4176         }
4177
4178         /**
4179          * Get the replica DB lag when the current transaction started
4180          *
4181          * This is useful when transactions might use snapshot isolation
4182          * (e.g. REPEATABLE-READ in innodb), so the "real" lag of that data
4183          * is this lag plus transaction duration. If they don't, it is still
4184          * safe to be pessimistic. This returns null if there is no transaction.
4185          *
4186          * This returns null if the lag status for this transaction was not yet recorded.
4187          *
4188          * @return array|null ('lag': seconds or false on error, 'since': UNIX timestamp of BEGIN)
4189          * @since 1.27
4190          */
4191         final protected function getRecordedTransactionLagStatus() {
4192                 return ( $this->trxLevel && $this->trxReplicaLag !== null )
4193                         ? [ 'lag' => $this->trxReplicaLag, 'since' => $this->trxTimestamp() ]
4194                         : null;
4195         }
4196
4197         /**
4198          * Get a replica DB lag estimate for this server
4199          *
4200          * @return array ('lag': seconds or false on error, 'since': UNIX timestamp of estimate)
4201          * @since 1.27
4202          */
4203         protected function getApproximateLagStatus() {
4204                 return [
4205                         'lag'   => $this->getLBInfo( 'replica' ) ? $this->getLag() : 0,
4206                         'since' => microtime( true )
4207                 ];
4208         }
4209
4210         /**
4211          * Merge the result of getSessionLagStatus() for several DBs
4212          * using the most pessimistic values to estimate the lag of
4213          * any data derived from them in combination
4214          *
4215          * This is information is useful for caching modules
4216          *
4217          * @see WANObjectCache::set()
4218          * @see WANObjectCache::getWithSetCallback()
4219          *
4220          * @param IDatabase $db1
4221          * @param IDatabase|null $db2 [optional]
4222          * @return array Map of values:
4223          *   - lag: highest lag of any of the DBs or false on error (e.g. replication stopped)
4224          *   - since: oldest UNIX timestamp of any of the DB lag estimates
4225          *   - pending: whether any of the DBs have uncommitted changes
4226          * @throws DBError
4227          * @since 1.27
4228          */
4229         public static function getCacheSetOptions( IDatabase $db1, IDatabase $db2 = null ) {
4230                 $res = [ 'lag' => 0, 'since' => INF, 'pending' => false ];
4231                 foreach ( func_get_args() as $db ) {
4232                         /** @var IDatabase $db */
4233                         $status = $db->getSessionLagStatus();
4234                         if ( $status['lag'] === false ) {
4235                                 $res['lag'] = false;
4236                         } elseif ( $res['lag'] !== false ) {
4237                                 $res['lag'] = max( $res['lag'], $status['lag'] );
4238                         }
4239                         $res['since'] = min( $res['since'], $status['since'] );
4240                         $res['pending'] = $res['pending'] ?: $db->writesPending();
4241                 }
4242
4243                 return $res;
4244         }
4245
4246         public function getLag() {
4247                 return 0;
4248         }
4249
4250         public function maxListLen() {
4251                 return 0;
4252         }
4253
4254         public function encodeBlob( $b ) {
4255                 return $b;
4256         }
4257
4258         public function decodeBlob( $b ) {
4259                 if ( $b instanceof Blob ) {
4260                         $b = $b->fetch();
4261                 }
4262                 return $b;
4263         }
4264
4265         public function setSessionOptions( array $options ) {
4266         }
4267
4268         public function sourceFile(
4269                 $filename,
4270                 callable $lineCallback = null,
4271                 callable $resultCallback = null,
4272                 $fname = false,
4273                 callable $inputCallback = null
4274         ) {
4275                 Wikimedia\suppressWarnings();
4276                 $fp = fopen( $filename, 'r' );
4277                 Wikimedia\restoreWarnings();
4278
4279                 if ( $fp === false ) {
4280                         throw new RuntimeException( "Could not open \"{$filename}\".\n" );
4281                 }
4282
4283                 if ( !$fname ) {
4284                         $fname = __METHOD__ . "( $filename )";
4285                 }
4286
4287                 try {
4288                         $error = $this->sourceStream(
4289                                 $fp, $lineCallback, $resultCallback, $fname, $inputCallback );
4290                 } catch ( Exception $e ) {
4291                         fclose( $fp );
4292                         throw $e;
4293                 }
4294
4295                 fclose( $fp );
4296
4297                 return $error;
4298         }
4299
4300         public function setSchemaVars( $vars ) {
4301                 $this->schemaVars = $vars;
4302         }
4303
4304         public function sourceStream(
4305                 $fp,
4306                 callable $lineCallback = null,
4307                 callable $resultCallback = null,
4308                 $fname = __METHOD__,
4309                 callable $inputCallback = null
4310         ) {
4311                 $delimiterReset = new ScopedCallback(
4312                         function ( $delimiter ) {
4313                                 $this->delimiter = $delimiter;
4314                         },
4315                         [ $this->delimiter ]
4316                 );
4317                 $cmd = '';
4318
4319                 while ( !feof( $fp ) ) {
4320                         if ( $lineCallback ) {
4321                                 call_user_func( $lineCallback );
4322                         }
4323
4324                         $line = trim( fgets( $fp ) );
4325
4326                         if ( $line == '' ) {
4327                                 continue;
4328                         }
4329
4330                         if ( $line[0] == '-' && $line[1] == '-' ) {
4331                                 continue;
4332                         }
4333
4334                         if ( $cmd != '' ) {
4335                                 $cmd .= ' ';
4336                         }
4337
4338                         $done = $this->streamStatementEnd( $cmd, $line );
4339
4340                         $cmd .= "$line\n";
4341
4342                         if ( $done || feof( $fp ) ) {
4343                                 $cmd = $this->replaceVars( $cmd );
4344
4345                                 if ( $inputCallback ) {
4346                                         $callbackResult = $inputCallback( $cmd );
4347
4348                                         if ( is_string( $callbackResult ) || !$callbackResult ) {
4349                                                 $cmd = $callbackResult;
4350                                         }
4351                                 }
4352
4353                                 if ( $cmd ) {
4354                                         $res = $this->query( $cmd, $fname );
4355
4356                                         if ( $resultCallback ) {
4357                                                 $resultCallback( $res, $this );
4358                                         }
4359
4360                                         if ( $res === false ) {
4361                                                 $err = $this->lastError();
4362
4363                                                 return "Query \"{$cmd}\" failed with error code \"$err\".\n";
4364                                         }
4365                                 }
4366                                 $cmd = '';
4367                         }
4368                 }
4369
4370                 ScopedCallback::consume( $delimiterReset );
4371                 return true;
4372         }
4373
4374         /**
4375          * Called by sourceStream() to check if we've reached a statement end
4376          *
4377          * @param string &$sql SQL assembled so far
4378          * @param string &$newLine New line about to be added to $sql
4379          * @return bool Whether $newLine contains end of the statement
4380          */
4381         public function streamStatementEnd( &$sql, &$newLine ) {
4382                 if ( $this->delimiter ) {
4383                         $prev = $newLine;
4384                         $newLine = preg_replace(
4385                                 '/' . preg_quote( $this->delimiter, '/' ) . '$/', '', $newLine );
4386                         if ( $newLine != $prev ) {
4387                                 return true;
4388                         }
4389                 }
4390
4391                 return false;
4392         }
4393
4394         /**
4395          * Database independent variable replacement. Replaces a set of variables
4396          * in an SQL statement with their contents as given by $this->getSchemaVars().
4397          *
4398          * Supports '{$var}' `{$var}` and / *$var* / (without the spaces) style variables.
4399          *
4400          * - '{$var}' should be used for text and is passed through the database's
4401          *   addQuotes method.
4402          * - `{$var}` should be used for identifiers (e.g. table and database names).
4403          *   It is passed through the database's addIdentifierQuotes method which
4404          *   can be overridden if the database uses something other than backticks.
4405          * - / *_* / or / *$wgDBprefix* / passes the name that follows through the
4406          *   database's tableName method.
4407          * - / *i* / passes the name that follows through the database's indexName method.
4408          * - In all other cases, / *$var* / is left unencoded. Except for table options,
4409          *   its use should be avoided. In 1.24 and older, string encoding was applied.
4410          *
4411          * @param string $ins SQL statement to replace variables in
4412          * @return string The new SQL statement with variables replaced
4413          */
4414         protected function replaceVars( $ins ) {
4415                 $vars = $this->getSchemaVars();
4416                 return preg_replace_callback(
4417                         '!
4418                                 /\* (\$wgDBprefix|[_i]) \*/ (\w*) | # 1-2. tableName, indexName
4419                                 \'\{\$ (\w+) }\'                  | # 3. addQuotes
4420                                 `\{\$ (\w+) }`                    | # 4. addIdentifierQuotes
4421                                 /\*\$ (\w+) \*/                     # 5. leave unencoded
4422                         !x',
4423                         function ( $m ) use ( $vars ) {
4424                                 // Note: Because of <https://bugs.php.net/bug.php?id=51881>,
4425                                 // check for both nonexistent keys *and* the empty string.
4426                                 if ( isset( $m[1] ) && $m[1] !== '' ) {
4427                                         if ( $m[1] === 'i' ) {
4428                                                 return $this->indexName( $m[2] );
4429                                         } else {
4430                                                 return $this->tableName( $m[2] );
4431                                         }
4432                                 } elseif ( isset( $m[3] ) && $m[3] !== '' && array_key_exists( $m[3], $vars ) ) {
4433                                         return $this->addQuotes( $vars[$m[3]] );
4434                                 } elseif ( isset( $m[4] ) && $m[4] !== '' && array_key_exists( $m[4], $vars ) ) {
4435                                         return $this->addIdentifierQuotes( $vars[$m[4]] );
4436                                 } elseif ( isset( $m[5] ) && $m[5] !== '' && array_key_exists( $m[5], $vars ) ) {
4437                                         return $vars[$m[5]];
4438                                 } else {
4439                                         return $m[0];
4440                                 }
4441                         },
4442                         $ins
4443                 );
4444         }
4445
4446         /**
4447          * Get schema variables. If none have been set via setSchemaVars(), then
4448          * use some defaults from the current object.
4449          *
4450          * @return array
4451          */
4452         protected function getSchemaVars() {
4453                 if ( $this->schemaVars ) {
4454                         return $this->schemaVars;
4455                 } else {
4456                         return $this->getDefaultSchemaVars();
4457                 }
4458         }
4459
4460         /**
4461          * Get schema variables to use if none have been set via setSchemaVars().
4462          *
4463          * Override this in derived classes to provide variables for tables.sql
4464          * and SQL patch files.
4465          *
4466          * @return array
4467          */
4468         protected function getDefaultSchemaVars() {
4469                 return [];
4470         }
4471
4472         public function lockIsFree( $lockName, $method ) {
4473                 // RDBMs methods for checking named locks may or may not count this thread itself.
4474                 // In MySQL, IS_FREE_LOCK() returns 0 if the thread already has the lock. This is
4475                 // the behavior choosen by the interface for this method.
4476                 return !isset( $this->namedLocksHeld[$lockName] );
4477         }
4478
4479         public function lock( $lockName, $method, $timeout = 5 ) {
4480                 $this->namedLocksHeld[$lockName] = 1;
4481
4482                 return true;
4483         }
4484
4485         public function unlock( $lockName, $method ) {
4486                 unset( $this->namedLocksHeld[$lockName] );
4487
4488                 return true;
4489         }
4490
4491         public function getScopedLockAndFlush( $lockKey, $fname, $timeout ) {
4492                 if ( $this->writesOrCallbacksPending() ) {
4493                         // This only flushes transactions to clear snapshots, not to write data
4494                         $fnames = implode( ', ', $this->pendingWriteAndCallbackCallers() );
4495                         throw new DBUnexpectedError(
4496                                 $this,
4497                                 "$fname: Cannot flush pre-lock snapshot because writes are pending ($fnames)."
4498                         );
4499                 }
4500
4501                 if ( !$this->lock( $lockKey, $fname, $timeout ) ) {
4502                         return null;
4503                 }
4504
4505                 $unlocker = new ScopedCallback( function () use ( $lockKey, $fname ) {
4506                         if ( $this->trxLevel() ) {
4507                                 // There is a good chance an exception was thrown, causing any early return
4508                                 // from the caller. Let any error handler get a chance to issue rollback().
4509                                 // If there isn't one, let the error bubble up and trigger server-side rollback.
4510                                 $this->onTransactionResolution(
4511                                         function () use ( $lockKey, $fname ) {
4512                                                 $this->unlock( $lockKey, $fname );
4513                                         },
4514                                         $fname
4515                                 );
4516                         } else {
4517                                 $this->unlock( $lockKey, $fname );
4518                         }
4519                 } );
4520
4521                 $this->commit( $fname, self::FLUSHING_INTERNAL );
4522
4523                 return $unlocker;
4524         }
4525
4526         public function namedLocksEnqueue() {
4527                 return false;
4528         }
4529
4530         public function tableLocksHaveTransactionScope() {
4531                 return true;
4532         }
4533
4534         final public function lockTables( array $read, array $write, $method ) {
4535                 if ( $this->writesOrCallbacksPending() ) {
4536                         throw new DBUnexpectedError( $this, "Transaction writes or callbacks still pending." );
4537                 }
4538
4539                 if ( $this->tableLocksHaveTransactionScope() ) {
4540                         $this->startAtomic( $method );
4541                 }
4542
4543                 return $this->doLockTables( $read, $write, $method );
4544         }
4545
4546         /**
4547          * Helper function for lockTables() that handles the actual table locking
4548          *
4549          * @param array $read Array of tables to lock for read access
4550          * @param array $write Array of tables to lock for write access
4551          * @param string $method Name of caller
4552          * @return true
4553          */
4554         protected function doLockTables( array $read, array $write, $method ) {
4555                 return true;
4556         }
4557
4558         final public function unlockTables( $method ) {
4559                 if ( $this->tableLocksHaveTransactionScope() ) {
4560                         $this->endAtomic( $method );
4561
4562                         return true; // locks released on COMMIT/ROLLBACK
4563                 }
4564
4565                 return $this->doUnlockTables( $method );
4566         }
4567
4568         /**
4569          * Helper function for unlockTables() that handles the actual table unlocking
4570          *
4571          * @param string $method Name of caller
4572          * @return true
4573          */
4574         protected function doUnlockTables( $method ) {
4575                 return true;
4576         }
4577
4578         /**
4579          * Delete a table
4580          * @param string $tableName
4581          * @param string $fName
4582          * @return bool|ResultWrapper
4583          * @since 1.18
4584          */
4585         public function dropTable( $tableName, $fName = __METHOD__ ) {
4586                 if ( !$this->tableExists( $tableName, $fName ) ) {
4587                         return false;
4588                 }
4589                 $sql = "DROP TABLE " . $this->tableName( $tableName ) . " CASCADE";
4590
4591                 return $this->query( $sql, $fName );
4592         }
4593
4594         public function getInfinity() {
4595                 return 'infinity';
4596         }
4597
4598         public function encodeExpiry( $expiry ) {
4599                 return ( $expiry == '' || $expiry == 'infinity' || $expiry == $this->getInfinity() )
4600                         ? $this->getInfinity()
4601                         : $this->timestamp( $expiry );
4602         }
4603
4604         public function decodeExpiry( $expiry, $format = TS_MW ) {
4605                 if ( $expiry == '' || $expiry == 'infinity' || $expiry == $this->getInfinity() ) {
4606                         return 'infinity';
4607                 }
4608
4609                 return ConvertibleTimestamp::convert( $format, $expiry );
4610         }
4611
4612         public function setBigSelects( $value = true ) {
4613                 // no-op
4614         }
4615
4616         public function isReadOnly() {
4617                 return ( $this->getReadOnlyReason() !== false );
4618         }
4619
4620         /**
4621          * @return string|bool Reason this DB is read-only or false if it is not
4622          */
4623         protected function getReadOnlyReason() {
4624                 $reason = $this->getLBInfo( 'readOnlyReason' );
4625
4626                 return is_string( $reason ) ? $reason : false;
4627         }
4628
4629         public function setTableAliases( array $aliases ) {
4630                 $this->tableAliases = $aliases;
4631         }
4632
4633         public function setIndexAliases( array $aliases ) {
4634                 $this->indexAliases = $aliases;
4635         }
4636
4637         /**
4638          * Get the underlying binding connection handle
4639          *
4640          * Makes sure the connection resource is set (disconnects and ping() failure can unset it).
4641          * This catches broken callers than catch and ignore disconnection exceptions.
4642          * Unlike checking isOpen(), this is safe to call inside of open().
4643          *
4644          * @return mixed
4645          * @throws DBUnexpectedError
4646          * @since 1.26
4647          */
4648         protected function getBindingHandle() {
4649                 if ( !$this->conn ) {
4650                         throw new DBUnexpectedError(
4651                                 $this,
4652                                 'DB connection was already closed or the connection dropped.'
4653                         );
4654                 }
4655
4656                 return $this->conn;
4657         }
4658
4659         /**
4660          * @since 1.19
4661          * @return string
4662          */
4663         public function __toString() {
4664                 return (string)$this->conn;
4665         }
4666
4667         /**
4668          * Make sure that copies do not share the same client binding handle
4669          * @throws DBConnectionError
4670          */
4671         public function __clone() {
4672                 $this->connLogger->warning(
4673                         "Cloning " . static::class . " is not recommended; forking connection:\n" .
4674                         ( new RuntimeException() )->getTraceAsString()
4675                 );
4676
4677                 if ( $this->isOpen() ) {
4678                         // Open a new connection resource without messing with the old one
4679                         $this->opened = false;
4680                         $this->conn = false;
4681                         $this->trxEndCallbacks = []; // don't copy
4682                         $this->handleSessionLoss(); // no trx or locks anymore
4683                         $this->open(
4684                                 $this->server,
4685                                 $this->user,
4686                                 $this->password,
4687                                 $this->getDBname(),
4688                                 $this->dbSchema(),
4689                                 $this->tablePrefix()
4690                         );
4691                         $this->lastPing = microtime( true );
4692                 }
4693         }
4694
4695         /**
4696          * Called by serialize. Throw an exception when DB connection is serialized.
4697          * This causes problems on some database engines because the connection is
4698          * not restored on unserialize.
4699          */
4700         public function __sleep() {
4701                 throw new RuntimeException( 'Database serialization may cause problems, since ' .
4702                         'the connection is not restored on wakeup.' );
4703         }
4704
4705         /**
4706          * Run a few simple sanity checks and close dangling connections
4707          */
4708         public function __destruct() {
4709                 if ( $this->trxLevel && $this->trxDoneWrites ) {
4710                         trigger_error( "Uncommitted DB writes (transaction from {$this->trxFname})." );
4711                 }
4712
4713                 $danglingWriters = $this->pendingWriteAndCallbackCallers();
4714                 if ( $danglingWriters ) {
4715                         $fnames = implode( ', ', $danglingWriters );
4716                         trigger_error( "DB transaction writes or callbacks still pending ($fnames)." );
4717                 }
4718
4719                 if ( $this->conn ) {
4720                         // Avoid connection leaks for sanity. Normally, resources close at script completion.
4721                         // The connection might already be closed in zend/hhvm by now, so suppress warnings.
4722                         Wikimedia\suppressWarnings();
4723                         $this->closeConnection();
4724                         Wikimedia\restoreWarnings();
4725                         $this->conn = false;
4726                         $this->opened = false;
4727                 }
4728         }
4729 }
4730
4731 /**
4732  * @deprecated since 1.28
4733  */
4734 class_alias( Database::class, 'DatabaseBase' );
4735
4736 /**
4737  * @deprecated since 1.29
4738  */
4739 class_alias( Database::class, 'Database' );