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 (bool)( $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                 // In theory this should work for any standards-compliant
2282                 // SQL implementation, although it may not be the best way to do it.
2283                 return "CAST( $field AS CHARACTER )";
2284         }
2285
2286         public function buildIntegerCast( $field ) {
2287                 return 'CAST( ' . $field . ' AS INTEGER )';
2288         }
2289
2290         public function buildSelectSubquery(
2291                 $table, $vars, $conds = '', $fname = __METHOD__,
2292                 $options = [], $join_conds = []
2293         ) {
2294                 return new Subquery(
2295                         $this->selectSQLText( $table, $vars, $conds, $fname, $options, $join_conds )
2296                 );
2297         }
2298
2299         public function databasesAreIndependent() {
2300                 return false;
2301         }
2302
2303         final public function selectDB( $db ) {
2304                 $this->selectDomain( new DatabaseDomain(
2305                         $db,
2306                         $this->currentDomain->getSchema(),
2307                         $this->currentDomain->getTablePrefix()
2308                 ) );
2309
2310                 return true;
2311         }
2312
2313         final public function selectDomain( $domain ) {
2314                 $this->doSelectDomain( DatabaseDomain::newFromId( $domain ) );
2315         }
2316
2317         protected function doSelectDomain( DatabaseDomain $domain ) {
2318                 $this->currentDomain = $domain;
2319         }
2320
2321         public function getDBname() {
2322                 return $this->currentDomain->getDatabase();
2323         }
2324
2325         public function getServer() {
2326                 return $this->server;
2327         }
2328
2329         public function tableName( $name, $format = 'quoted' ) {
2330                 if ( $name instanceof Subquery ) {
2331                         throw new DBUnexpectedError(
2332                                 $this,
2333                                 __METHOD__ . ': got Subquery instance when expecting a string.'
2334                         );
2335                 }
2336
2337                 # Skip the entire process when we have a string quoted on both ends.
2338                 # Note that we check the end so that we will still quote any use of
2339                 # use of `database`.table. But won't break things if someone wants
2340                 # to query a database table with a dot in the name.
2341                 if ( $this->isQuotedIdentifier( $name ) ) {
2342                         return $name;
2343                 }
2344
2345                 # Lets test for any bits of text that should never show up in a table
2346                 # name. Basically anything like JOIN or ON which are actually part of
2347                 # SQL queries, but may end up inside of the table value to combine
2348                 # sql. Such as how the API is doing.
2349                 # Note that we use a whitespace test rather than a \b test to avoid
2350                 # any remote case where a word like on may be inside of a table name
2351                 # surrounded by symbols which may be considered word breaks.
2352                 if ( preg_match( '/(^|\s)(DISTINCT|JOIN|ON|AS)(\s|$)/i', $name ) !== 0 ) {
2353                         $this->queryLogger->warning(
2354                                 __METHOD__ . ": use of subqueries is not supported this way.",
2355                                 [ 'trace' => ( new RuntimeException() )->getTraceAsString() ]
2356                         );
2357
2358                         return $name;
2359                 }
2360
2361                 # Split database and table into proper variables.
2362                 list( $database, $schema, $prefix, $table ) = $this->qualifiedTableComponents( $name );
2363
2364                 # Quote $table and apply the prefix if not quoted.
2365                 # $tableName might be empty if this is called from Database::replaceVars()
2366                 $tableName = "{$prefix}{$table}";
2367                 if ( $format === 'quoted'
2368                         && !$this->isQuotedIdentifier( $tableName )
2369                         && $tableName !== ''
2370                 ) {
2371                         $tableName = $this->addIdentifierQuotes( $tableName );
2372                 }
2373
2374                 # Quote $schema and $database and merge them with the table name if needed
2375                 $tableName = $this->prependDatabaseOrSchema( $schema, $tableName, $format );
2376                 $tableName = $this->prependDatabaseOrSchema( $database, $tableName, $format );
2377
2378                 return $tableName;
2379         }
2380
2381         /**
2382          * Get the table components needed for a query given the currently selected database
2383          *
2384          * @param string $name Table name in the form of db.schema.table, db.table, or table
2385          * @return array (DB name or "" for default, schema name, table prefix, table name)
2386          */
2387         protected function qualifiedTableComponents( $name ) {
2388                 # We reverse the explode so that database.table and table both output the correct table.
2389                 $dbDetails = explode( '.', $name, 3 );
2390                 if ( count( $dbDetails ) == 3 ) {
2391                         list( $database, $schema, $table ) = $dbDetails;
2392                         # We don't want any prefix added in this case
2393                         $prefix = '';
2394                 } elseif ( count( $dbDetails ) == 2 ) {
2395                         list( $database, $table ) = $dbDetails;
2396                         # We don't want any prefix added in this case
2397                         $prefix = '';
2398                         # In dbs that support it, $database may actually be the schema
2399                         # but that doesn't affect any of the functionality here
2400                         $schema = '';
2401                 } else {
2402                         list( $table ) = $dbDetails;
2403                         if ( isset( $this->tableAliases[$table] ) ) {
2404                                 $database = $this->tableAliases[$table]['dbname'];
2405                                 $schema = is_string( $this->tableAliases[$table]['schema'] )
2406                                         ? $this->tableAliases[$table]['schema']
2407                                         : $this->relationSchemaQualifier();
2408                                 $prefix = is_string( $this->tableAliases[$table]['prefix'] )
2409                                         ? $this->tableAliases[$table]['prefix']
2410                                         : $this->tablePrefix();
2411                         } else {
2412                                 $database = '';
2413                                 $schema = $this->relationSchemaQualifier(); # Default schema
2414                                 $prefix = $this->tablePrefix(); # Default prefix
2415                         }
2416                 }
2417
2418                 return [ $database, $schema, $prefix, $table ];
2419         }
2420
2421         /**
2422          * @param string|null $namespace Database or schema
2423          * @param string $relation Name of table, view, sequence, etc...
2424          * @param string $format One of (raw, quoted)
2425          * @return string Relation name with quoted and merged $namespace as needed
2426          */
2427         private function prependDatabaseOrSchema( $namespace, $relation, $format ) {
2428                 if ( strlen( $namespace ) ) {
2429                         if ( $format === 'quoted' && !$this->isQuotedIdentifier( $namespace ) ) {
2430                                 $namespace = $this->addIdentifierQuotes( $namespace );
2431                         }
2432                         $relation = $namespace . '.' . $relation;
2433                 }
2434
2435                 return $relation;
2436         }
2437
2438         public function tableNames() {
2439                 $inArray = func_get_args();
2440                 $retVal = [];
2441
2442                 foreach ( $inArray as $name ) {
2443                         $retVal[$name] = $this->tableName( $name );
2444                 }
2445
2446                 return $retVal;
2447         }
2448
2449         public function tableNamesN() {
2450                 $inArray = func_get_args();
2451                 $retVal = [];
2452
2453                 foreach ( $inArray as $name ) {
2454                         $retVal[] = $this->tableName( $name );
2455                 }
2456
2457                 return $retVal;
2458         }
2459
2460         /**
2461          * Get an aliased table name
2462          *
2463          * This returns strings like "tableName AS newTableName" for aliased tables
2464          * and "(SELECT * from tableA) newTablename" for subqueries (e.g. derived tables)
2465          *
2466          * @see Database::tableName()
2467          * @param string|Subquery $table Table name or object with a 'sql' field
2468          * @param string|bool $alias Table alias (optional)
2469          * @return string SQL name for aliased table. Will not alias a table to its own name
2470          */
2471         protected function tableNameWithAlias( $table, $alias = false ) {
2472                 if ( is_string( $table ) ) {
2473                         $quotedTable = $this->tableName( $table );
2474                 } elseif ( $table instanceof Subquery ) {
2475                         $quotedTable = (string)$table;
2476                 } else {
2477                         throw new InvalidArgumentException( "Table must be a string or Subquery." );
2478                 }
2479
2480                 if ( !strlen( $alias ) || $alias === $table ) {
2481                         if ( $table instanceof Subquery ) {
2482                                 throw new InvalidArgumentException( "Subquery table missing alias." );
2483                         }
2484
2485                         return $quotedTable;
2486                 } else {
2487                         return $quotedTable . ' ' . $this->addIdentifierQuotes( $alias );
2488                 }
2489         }
2490
2491         /**
2492          * Gets an array of aliased table names
2493          *
2494          * @param array $tables [ [alias] => table ]
2495          * @return string[] See tableNameWithAlias()
2496          */
2497         protected function tableNamesWithAlias( $tables ) {
2498                 $retval = [];
2499                 foreach ( $tables as $alias => $table ) {
2500                         if ( is_numeric( $alias ) ) {
2501                                 $alias = $table;
2502                         }
2503                         $retval[] = $this->tableNameWithAlias( $table, $alias );
2504                 }
2505
2506                 return $retval;
2507         }
2508
2509         /**
2510          * Get an aliased field name
2511          * e.g. fieldName AS newFieldName
2512          *
2513          * @param string $name Field name
2514          * @param string|bool $alias Alias (optional)
2515          * @return string SQL name for aliased field. Will not alias a field to its own name
2516          */
2517         protected function fieldNameWithAlias( $name, $alias = false ) {
2518                 if ( !$alias || (string)$alias === (string)$name ) {
2519                         return $name;
2520                 } else {
2521                         return $name . ' AS ' . $this->addIdentifierQuotes( $alias ); // PostgreSQL needs AS
2522                 }
2523         }
2524
2525         /**
2526          * Gets an array of aliased field names
2527          *
2528          * @param array $fields [ [alias] => field ]
2529          * @return string[] See fieldNameWithAlias()
2530          */
2531         protected function fieldNamesWithAlias( $fields ) {
2532                 $retval = [];
2533                 foreach ( $fields as $alias => $field ) {
2534                         if ( is_numeric( $alias ) ) {
2535                                 $alias = $field;
2536                         }
2537                         $retval[] = $this->fieldNameWithAlias( $field, $alias );
2538                 }
2539
2540                 return $retval;
2541         }
2542
2543         /**
2544          * Get the aliased table name clause for a FROM clause
2545          * which might have a JOIN and/or USE INDEX or IGNORE INDEX clause
2546          *
2547          * @param array $tables ( [alias] => table )
2548          * @param array $use_index Same as for select()
2549          * @param array $ignore_index Same as for select()
2550          * @param array $join_conds Same as for select()
2551          * @return string
2552          */
2553         protected function tableNamesWithIndexClauseOrJOIN(
2554                 $tables, $use_index = [], $ignore_index = [], $join_conds = []
2555         ) {
2556                 $ret = [];
2557                 $retJOIN = [];
2558                 $use_index = (array)$use_index;
2559                 $ignore_index = (array)$ignore_index;
2560                 $join_conds = (array)$join_conds;
2561
2562                 foreach ( $tables as $alias => $table ) {
2563                         if ( !is_string( $alias ) ) {
2564                                 // No alias? Set it equal to the table name
2565                                 $alias = $table;
2566                         }
2567
2568                         if ( is_array( $table ) ) {
2569                                 // A parenthesized group
2570                                 if ( count( $table ) > 1 ) {
2571                                         $joinedTable = '(' .
2572                                                 $this->tableNamesWithIndexClauseOrJOIN(
2573                                                         $table, $use_index, $ignore_index, $join_conds ) . ')';
2574                                 } else {
2575                                         // Degenerate case
2576                                         $innerTable = reset( $table );
2577                                         $innerAlias = key( $table );
2578                                         $joinedTable = $this->tableNameWithAlias(
2579                                                 $innerTable,
2580                                                 is_string( $innerAlias ) ? $innerAlias : $innerTable
2581                                         );
2582                                 }
2583                         } else {
2584                                 $joinedTable = $this->tableNameWithAlias( $table, $alias );
2585                         }
2586
2587                         // Is there a JOIN clause for this table?
2588                         if ( isset( $join_conds[$alias] ) ) {
2589                                 list( $joinType, $conds ) = $join_conds[$alias];
2590                                 $tableClause = $joinType;
2591                                 $tableClause .= ' ' . $joinedTable;
2592                                 if ( isset( $use_index[$alias] ) ) { // has USE INDEX?
2593                                         $use = $this->useIndexClause( implode( ',', (array)$use_index[$alias] ) );
2594                                         if ( $use != '' ) {
2595                                                 $tableClause .= ' ' . $use;
2596                                         }
2597                                 }
2598                                 if ( isset( $ignore_index[$alias] ) ) { // has IGNORE INDEX?
2599                                         $ignore = $this->ignoreIndexClause(
2600                                                 implode( ',', (array)$ignore_index[$alias] ) );
2601                                         if ( $ignore != '' ) {
2602                                                 $tableClause .= ' ' . $ignore;
2603                                         }
2604                                 }
2605                                 $on = $this->makeList( (array)$conds, self::LIST_AND );
2606                                 if ( $on != '' ) {
2607                                         $tableClause .= ' ON (' . $on . ')';
2608                                 }
2609
2610                                 $retJOIN[] = $tableClause;
2611                         } elseif ( isset( $use_index[$alias] ) ) {
2612                                 // Is there an INDEX clause for this table?
2613                                 $tableClause = $joinedTable;
2614                                 $tableClause .= ' ' . $this->useIndexClause(
2615                                                 implode( ',', (array)$use_index[$alias] )
2616                                         );
2617
2618                                 $ret[] = $tableClause;
2619                         } elseif ( isset( $ignore_index[$alias] ) ) {
2620                                 // Is there an INDEX clause for this table?
2621                                 $tableClause = $joinedTable;
2622                                 $tableClause .= ' ' . $this->ignoreIndexClause(
2623                                                 implode( ',', (array)$ignore_index[$alias] )
2624                                         );
2625
2626                                 $ret[] = $tableClause;
2627                         } else {
2628                                 $tableClause = $joinedTable;
2629
2630                                 $ret[] = $tableClause;
2631                         }
2632                 }
2633
2634                 // We can't separate explicit JOIN clauses with ',', use ' ' for those
2635                 $implicitJoins = $ret ? implode( ',', $ret ) : "";
2636                 $explicitJoins = $retJOIN ? implode( ' ', $retJOIN ) : "";
2637
2638                 // Compile our final table clause
2639                 return implode( ' ', [ $implicitJoins, $explicitJoins ] );
2640         }
2641
2642         /**
2643          * Allows for index remapping in queries where this is not consistent across DBMS
2644          *
2645          * @param string $index
2646          * @return string
2647          */
2648         protected function indexName( $index ) {
2649                 return $this->indexAliases[$index] ?? $index;
2650         }
2651
2652         public function addQuotes( $s ) {
2653                 if ( $s instanceof Blob ) {
2654                         $s = $s->fetch();
2655                 }
2656                 if ( $s === null ) {
2657                         return 'NULL';
2658                 } elseif ( is_bool( $s ) ) {
2659                         return (int)$s;
2660                 } else {
2661                         # This will also quote numeric values. This should be harmless,
2662                         # and protects against weird problems that occur when they really
2663                         # _are_ strings such as article titles and string->number->string
2664                         # conversion is not 1:1.
2665                         return "'" . $this->strencode( $s ) . "'";
2666                 }
2667         }
2668
2669         /**
2670          * Quotes an identifier using `backticks` or "double quotes" depending on the database type.
2671          * MySQL uses `backticks` while basically everything else uses double quotes.
2672          * Since MySQL is the odd one out here the double quotes are our generic
2673          * and we implement backticks in DatabaseMysqlBase.
2674          *
2675          * @param string $s
2676          * @return string
2677          */
2678         public function addIdentifierQuotes( $s ) {
2679                 return '"' . str_replace( '"', '""', $s ) . '"';
2680         }
2681
2682         /**
2683          * Returns if the given identifier looks quoted or not according to
2684          * the database convention for quoting identifiers .
2685          *
2686          * @note Do not use this to determine if untrusted input is safe.
2687          *   A malicious user can trick this function.
2688          * @param string $name
2689          * @return bool
2690          */
2691         public function isQuotedIdentifier( $name ) {
2692                 return $name[0] == '"' && substr( $name, -1, 1 ) == '"';
2693         }
2694
2695         /**
2696          * @param string $s
2697          * @param string $escapeChar
2698          * @return string
2699          */
2700         protected function escapeLikeInternal( $s, $escapeChar = '`' ) {
2701                 return str_replace( [ $escapeChar, '%', '_' ],
2702                         [ "{$escapeChar}{$escapeChar}", "{$escapeChar}%", "{$escapeChar}_" ],
2703                         $s );
2704         }
2705
2706         public function buildLike() {
2707                 $params = func_get_args();
2708
2709                 if ( count( $params ) > 0 && is_array( $params[0] ) ) {
2710                         $params = $params[0];
2711                 }
2712
2713                 $s = '';
2714
2715                 // We use ` instead of \ as the default LIKE escape character, since addQuotes()
2716                 // may escape backslashes, creating problems of double escaping. The `
2717                 // character has good cross-DBMS compatibility, avoiding special operators
2718                 // in MS SQL like ^ and %
2719                 $escapeChar = '`';
2720
2721                 foreach ( $params as $value ) {
2722                         if ( $value instanceof LikeMatch ) {
2723                                 $s .= $value->toString();
2724                         } else {
2725                                 $s .= $this->escapeLikeInternal( $value, $escapeChar );
2726                         }
2727                 }
2728
2729                 return ' LIKE ' .
2730                         $this->addQuotes( $s ) . ' ESCAPE ' . $this->addQuotes( $escapeChar ) . ' ';
2731         }
2732
2733         public function anyChar() {
2734                 return new LikeMatch( '_' );
2735         }
2736
2737         public function anyString() {
2738                 return new LikeMatch( '%' );
2739         }
2740
2741         public function nextSequenceValue( $seqName ) {
2742                 return null;
2743         }
2744
2745         /**
2746          * USE INDEX clause. Unlikely to be useful for anything but MySQL. This
2747          * is only needed because a) MySQL must be as efficient as possible due to
2748          * its use on Wikipedia, and b) MySQL 4.0 is kind of dumb sometimes about
2749          * which index to pick. Anyway, other databases might have different
2750          * indexes on a given table. So don't bother overriding this unless you're
2751          * MySQL.
2752          * @param string $index
2753          * @return string
2754          */
2755         public function useIndexClause( $index ) {
2756                 return '';
2757         }
2758
2759         /**
2760          * IGNORE INDEX clause. Unlikely to be useful for anything but MySQL. This
2761          * is only needed because a) MySQL must be as efficient as possible due to
2762          * its use on Wikipedia, and b) MySQL 4.0 is kind of dumb sometimes about
2763          * which index to pick. Anyway, other databases might have different
2764          * indexes on a given table. So don't bother overriding this unless you're
2765          * MySQL.
2766          * @param string $index
2767          * @return string
2768          */
2769         public function ignoreIndexClause( $index ) {
2770                 return '';
2771         }
2772
2773         public function replace( $table, $uniqueIndexes, $rows, $fname = __METHOD__ ) {
2774                 if ( count( $rows ) == 0 ) {
2775                         return;
2776                 }
2777
2778                 // Single row case
2779                 if ( !is_array( reset( $rows ) ) ) {
2780                         $rows = [ $rows ];
2781                 }
2782
2783                 try {
2784                         $this->startAtomic( $fname, self::ATOMIC_CANCELABLE );
2785                         $affectedRowCount = 0;
2786                         foreach ( $rows as $row ) {
2787                                 // Delete rows which collide with this one
2788                                 $indexWhereClauses = [];
2789                                 foreach ( $uniqueIndexes as $index ) {
2790                                         $indexColumns = (array)$index;
2791                                         $indexRowValues = array_intersect_key( $row, array_flip( $indexColumns ) );
2792                                         if ( count( $indexRowValues ) != count( $indexColumns ) ) {
2793                                                 throw new DBUnexpectedError(
2794                                                         $this,
2795                                                         'New record does not provide all values for unique key (' .
2796                                                         implode( ', ', $indexColumns ) . ')'
2797                                                 );
2798                                         } elseif ( in_array( null, $indexRowValues, true ) ) {
2799                                                 throw new DBUnexpectedError(
2800                                                         $this,
2801                                                         'New record has a null value for unique key (' .
2802                                                         implode( ', ', $indexColumns ) . ')'
2803                                                 );
2804                                         }
2805                                         $indexWhereClauses[] = $this->makeList( $indexRowValues, LIST_AND );
2806                                 }
2807
2808                                 if ( $indexWhereClauses ) {
2809                                         $this->delete( $table, $this->makeList( $indexWhereClauses, LIST_OR ), $fname );
2810                                         $affectedRowCount += $this->affectedRows();
2811                                 }
2812
2813                                 // Now insert the row
2814                                 $this->insert( $table, $row, $fname );
2815                                 $affectedRowCount += $this->affectedRows();
2816                         }
2817                         $this->endAtomic( $fname );
2818                         $this->affectedRowCount = $affectedRowCount;
2819                 } catch ( Exception $e ) {
2820                         $this->cancelAtomic( $fname );
2821                         throw $e;
2822                 }
2823         }
2824
2825         /**
2826          * REPLACE query wrapper for MySQL and SQLite, which have a native REPLACE
2827          * statement.
2828          *
2829          * @param string $table Table name
2830          * @param array|string $rows Row(s) to insert
2831          * @param string $fname Caller function name
2832          */
2833         protected function nativeReplace( $table, $rows, $fname ) {
2834                 $table = $this->tableName( $table );
2835
2836                 # Single row case
2837                 if ( !is_array( reset( $rows ) ) ) {
2838                         $rows = [ $rows ];
2839                 }
2840
2841                 $sql = "REPLACE INTO $table (" . implode( ',', array_keys( $rows[0] ) ) . ') VALUES ';
2842                 $first = true;
2843
2844                 foreach ( $rows as $row ) {
2845                         if ( $first ) {
2846                                 $first = false;
2847                         } else {
2848                                 $sql .= ',';
2849                         }
2850
2851                         $sql .= '(' . $this->makeList( $row ) . ')';
2852                 }
2853
2854                 $this->query( $sql, $fname );
2855         }
2856
2857         public function upsert( $table, array $rows, array $uniqueIndexes, array $set,
2858                 $fname = __METHOD__
2859         ) {
2860                 if ( $rows === [] ) {
2861                         return true; // nothing to do
2862                 }
2863
2864                 if ( !is_array( reset( $rows ) ) ) {
2865                         $rows = [ $rows ];
2866                 }
2867
2868                 if ( count( $uniqueIndexes ) ) {
2869                         $clauses = []; // list WHERE clauses that each identify a single row
2870                         foreach ( $rows as $row ) {
2871                                 foreach ( $uniqueIndexes as $index ) {
2872                                         $index = is_array( $index ) ? $index : [ $index ]; // columns
2873                                         $rowKey = []; // unique key to this row
2874                                         foreach ( $index as $column ) {
2875                                                 $rowKey[$column] = $row[$column];
2876                                         }
2877                                         $clauses[] = $this->makeList( $rowKey, self::LIST_AND );
2878                                 }
2879                         }
2880                         $where = [ $this->makeList( $clauses, self::LIST_OR ) ];
2881                 } else {
2882                         $where = false;
2883                 }
2884
2885                 $affectedRowCount = 0;
2886                 try {
2887                         $this->startAtomic( $fname, self::ATOMIC_CANCELABLE );
2888                         # Update any existing conflicting row(s)
2889                         if ( $where !== false ) {
2890                                 $this->update( $table, $set, $where, $fname );
2891                                 $affectedRowCount += $this->affectedRows();
2892                         }
2893                         # Now insert any non-conflicting row(s)
2894                         $this->insert( $table, $rows, $fname, [ 'IGNORE' ] );
2895                         $affectedRowCount += $this->affectedRows();
2896                         $this->endAtomic( $fname );
2897                         $this->affectedRowCount = $affectedRowCount;
2898                 } catch ( Exception $e ) {
2899                         $this->cancelAtomic( $fname );
2900                         throw $e;
2901                 }
2902
2903                 return true;
2904         }
2905
2906         public function deleteJoin( $delTable, $joinTable, $delVar, $joinVar, $conds,
2907                 $fname = __METHOD__
2908         ) {
2909                 if ( !$conds ) {
2910                         throw new DBUnexpectedError( $this, __METHOD__ . ' called with empty $conds' );
2911                 }
2912
2913                 $delTable = $this->tableName( $delTable );
2914                 $joinTable = $this->tableName( $joinTable );
2915                 $sql = "DELETE FROM $delTable WHERE $delVar IN (SELECT $joinVar FROM $joinTable ";
2916                 if ( $conds != '*' ) {
2917                         $sql .= 'WHERE ' . $this->makeList( $conds, self::LIST_AND );
2918                 }
2919                 $sql .= ')';
2920
2921                 $this->query( $sql, $fname );
2922         }
2923
2924         public function textFieldSize( $table, $field ) {
2925                 $table = $this->tableName( $table );
2926                 $sql = "SHOW COLUMNS FROM $table LIKE \"$field\";";
2927                 $res = $this->query( $sql, __METHOD__ );
2928                 $row = $this->fetchObject( $res );
2929
2930                 $m = [];
2931
2932                 if ( preg_match( '/\((.*)\)/', $row->Type, $m ) ) {
2933                         $size = $m[1];
2934                 } else {
2935                         $size = -1;
2936                 }
2937
2938                 return $size;
2939         }
2940
2941         public function delete( $table, $conds, $fname = __METHOD__ ) {
2942                 if ( !$conds ) {
2943                         throw new DBUnexpectedError( $this, __METHOD__ . ' called with no conditions' );
2944                 }
2945
2946                 $table = $this->tableName( $table );
2947                 $sql = "DELETE FROM $table";
2948
2949                 if ( $conds != '*' ) {
2950                         if ( is_array( $conds ) ) {
2951                                 $conds = $this->makeList( $conds, self::LIST_AND );
2952                         }
2953                         $sql .= ' WHERE ' . $conds;
2954                 }
2955
2956                 $this->query( $sql, $fname );
2957
2958                 return true;
2959         }
2960
2961         final public function insertSelect(
2962                 $destTable, $srcTable, $varMap, $conds,
2963                 $fname = __METHOD__, $insertOptions = [], $selectOptions = [], $selectJoinConds = []
2964         ) {
2965                 static $hints = [ 'NO_AUTO_COLUMNS' ];
2966
2967                 $insertOptions = (array)$insertOptions;
2968                 $selectOptions = (array)$selectOptions;
2969
2970                 if ( $this->cliMode && $this->isInsertSelectSafe( $insertOptions, $selectOptions ) ) {
2971                         // For massive migrations with downtime, we don't want to select everything
2972                         // into memory and OOM, so do all this native on the server side if possible.
2973                         $this->nativeInsertSelect(
2974                                 $destTable,
2975                                 $srcTable,
2976                                 $varMap,
2977                                 $conds,
2978                                 $fname,
2979                                 array_diff( $insertOptions, $hints ),
2980                                 $selectOptions,
2981                                 $selectJoinConds
2982                         );
2983                 } else {
2984                         $this->nonNativeInsertSelect(
2985                                 $destTable,
2986                                 $srcTable,
2987                                 $varMap,
2988                                 $conds,
2989                                 $fname,
2990                                 array_diff( $insertOptions, $hints ),
2991                                 $selectOptions,
2992                                 $selectJoinConds
2993                         );
2994                 }
2995
2996                 return true;
2997         }
2998
2999         /**
3000          * @param array $insertOptions INSERT options
3001          * @param array $selectOptions SELECT options
3002          * @return bool Whether an INSERT SELECT with these options will be replication safe
3003          * @since 1.31
3004          */
3005         protected function isInsertSelectSafe( array $insertOptions, array $selectOptions ) {
3006                 return true;
3007         }
3008
3009         /**
3010          * Implementation of insertSelect() based on select() and insert()
3011          *
3012          * @see IDatabase::insertSelect()
3013          * @since 1.30
3014          * @param string $destTable
3015          * @param string|array $srcTable
3016          * @param array $varMap
3017          * @param array $conds
3018          * @param string $fname
3019          * @param array $insertOptions
3020          * @param array $selectOptions
3021          * @param array $selectJoinConds
3022          */
3023         protected function nonNativeInsertSelect( $destTable, $srcTable, $varMap, $conds,
3024                 $fname = __METHOD__,
3025                 $insertOptions = [], $selectOptions = [], $selectJoinConds = []
3026         ) {
3027                 // For web requests, do a locking SELECT and then INSERT. This puts the SELECT burden
3028                 // on only the master (without needing row-based-replication). It also makes it easy to
3029                 // know how big the INSERT is going to be.
3030                 $fields = [];
3031                 foreach ( $varMap as $dstColumn => $sourceColumnOrSql ) {
3032                         $fields[] = $this->fieldNameWithAlias( $sourceColumnOrSql, $dstColumn );
3033                 }
3034                 $selectOptions[] = 'FOR UPDATE';
3035                 $res = $this->select(
3036                         $srcTable, implode( ',', $fields ), $conds, $fname, $selectOptions, $selectJoinConds
3037                 );
3038                 if ( !$res ) {
3039                         return;
3040                 }
3041
3042                 try {
3043                         $affectedRowCount = 0;
3044                         $this->startAtomic( $fname, self::ATOMIC_CANCELABLE );
3045                         $rows = [];
3046                         $ok = true;
3047                         foreach ( $res as $row ) {
3048                                 $rows[] = (array)$row;
3049
3050                                 // Avoid inserts that are too huge
3051                                 if ( count( $rows ) >= $this->nonNativeInsertSelectBatchSize ) {
3052                                         $ok = $this->insert( $destTable, $rows, $fname, $insertOptions );
3053                                         if ( !$ok ) {
3054                                                 break;
3055                                         }
3056                                         $affectedRowCount += $this->affectedRows();
3057                                         $rows = [];
3058                                 }
3059                         }
3060                         if ( $rows && $ok ) {
3061                                 $ok = $this->insert( $destTable, $rows, $fname, $insertOptions );
3062                                 if ( $ok ) {
3063                                         $affectedRowCount += $this->affectedRows();
3064                                 }
3065                         }
3066                         if ( $ok ) {
3067                                 $this->endAtomic( $fname );
3068                                 $this->affectedRowCount = $affectedRowCount;
3069                         } else {
3070                                 $this->cancelAtomic( $fname );
3071                         }
3072                 } catch ( Exception $e ) {
3073                         $this->cancelAtomic( $fname );
3074                         throw $e;
3075                 }
3076         }
3077
3078         /**
3079          * Native server-side implementation of insertSelect() for situations where
3080          * we don't want to select everything into memory
3081          *
3082          * @see IDatabase::insertSelect()
3083          * @param string $destTable
3084          * @param string|array $srcTable
3085          * @param array $varMap
3086          * @param array $conds
3087          * @param string $fname
3088          * @param array $insertOptions
3089          * @param array $selectOptions
3090          * @param array $selectJoinConds
3091          */
3092         protected function nativeInsertSelect( $destTable, $srcTable, $varMap, $conds,
3093                 $fname = __METHOD__,
3094                 $insertOptions = [], $selectOptions = [], $selectJoinConds = []
3095         ) {
3096                 $destTable = $this->tableName( $destTable );
3097
3098                 if ( !is_array( $insertOptions ) ) {
3099                         $insertOptions = [ $insertOptions ];
3100                 }
3101
3102                 $insertOptions = $this->makeInsertOptions( $insertOptions );
3103
3104                 $selectSql = $this->selectSQLText(
3105                         $srcTable,
3106                         array_values( $varMap ),
3107                         $conds,
3108                         $fname,
3109                         $selectOptions,
3110                         $selectJoinConds
3111                 );
3112
3113                 $sql = "INSERT $insertOptions" .
3114                         " INTO $destTable (" . implode( ',', array_keys( $varMap ) ) . ') ' .
3115                         $selectSql;
3116
3117                 $this->query( $sql, $fname );
3118         }
3119
3120         /**
3121          * Construct a LIMIT query with optional offset. This is used for query
3122          * pages. The SQL should be adjusted so that only the first $limit rows
3123          * are returned. If $offset is provided as well, then the first $offset
3124          * rows should be discarded, and the next $limit rows should be returned.
3125          * If the result of the query is not ordered, then the rows to be returned
3126          * are theoretically arbitrary.
3127          *
3128          * $sql is expected to be a SELECT, if that makes a difference.
3129          *
3130          * The version provided by default works in MySQL and SQLite. It will very
3131          * likely need to be overridden for most other DBMSes.
3132          *
3133          * @param string $sql SQL query we will append the limit too
3134          * @param int $limit The SQL limit
3135          * @param int|bool $offset The SQL offset (default false)
3136          * @throws DBUnexpectedError
3137          * @return string
3138          */
3139         public function limitResult( $sql, $limit, $offset = false ) {
3140                 if ( !is_numeric( $limit ) ) {
3141                         throw new DBUnexpectedError( $this,
3142                                 "Invalid non-numeric limit passed to limitResult()\n" );
3143                 }
3144
3145                 return "$sql LIMIT "
3146                 . ( ( is_numeric( $offset ) && $offset != 0 ) ? "{$offset}," : "" )
3147                 . "{$limit} ";
3148         }
3149
3150         public function unionSupportsOrderAndLimit() {
3151                 return true; // True for almost every DB supported
3152         }
3153
3154         public function unionQueries( $sqls, $all ) {
3155                 $glue = $all ? ') UNION ALL (' : ') UNION (';
3156
3157                 return '(' . implode( $glue, $sqls ) . ')';
3158         }
3159
3160         public function unionConditionPermutations(
3161                 $table, $vars, array $permute_conds, $extra_conds = '', $fname = __METHOD__,
3162                 $options = [], $join_conds = []
3163         ) {
3164                 // First, build the Cartesian product of $permute_conds
3165                 $conds = [ [] ];
3166                 foreach ( $permute_conds as $field => $values ) {
3167                         if ( !$values ) {
3168                                 // Skip empty $values
3169                                 continue;
3170                         }
3171                         $values = array_unique( $values ); // For sanity
3172                         $newConds = [];
3173                         foreach ( $conds as $cond ) {
3174                                 foreach ( $values as $value ) {
3175                                         $cond[$field] = $value;
3176                                         $newConds[] = $cond; // Arrays are by-value, not by-reference, so this works
3177                                 }
3178                         }
3179                         $conds = $newConds;
3180                 }
3181
3182                 $extra_conds = $extra_conds === '' ? [] : (array)$extra_conds;
3183
3184                 // If there's just one condition and no subordering, hand off to
3185                 // selectSQLText directly.
3186                 if ( count( $conds ) === 1 &&
3187                         ( !isset( $options['INNER ORDER BY'] ) || !$this->unionSupportsOrderAndLimit() )
3188                 ) {
3189                         return $this->selectSQLText(
3190                                 $table, $vars, $conds[0] + $extra_conds, $fname, $options, $join_conds
3191                         );
3192                 }
3193
3194                 // Otherwise, we need to pull out the order and limit to apply after
3195                 // the union. Then build the SQL queries for each set of conditions in
3196                 // $conds. Then union them together (using UNION ALL, because the
3197                 // product *should* already be distinct).
3198                 $orderBy = $this->makeOrderBy( $options );
3199                 $limit = $options['LIMIT'] ?? null;
3200                 $offset = $options['OFFSET'] ?? false;
3201                 $all = empty( $options['NOTALL'] ) && !in_array( 'NOTALL', $options );
3202                 if ( !$this->unionSupportsOrderAndLimit() ) {
3203                         unset( $options['ORDER BY'], $options['LIMIT'], $options['OFFSET'] );
3204                 } else {
3205                         if ( array_key_exists( 'INNER ORDER BY', $options ) ) {
3206                                 $options['ORDER BY'] = $options['INNER ORDER BY'];
3207                         }
3208                         if ( $limit !== null && is_numeric( $offset ) && $offset != 0 ) {
3209                                 // We need to increase the limit by the offset rather than
3210                                 // using the offset directly, otherwise it'll skip incorrectly
3211                                 // in the subqueries.
3212                                 $options['LIMIT'] = $limit + $offset;
3213                                 unset( $options['OFFSET'] );
3214                         }
3215                 }
3216
3217                 $sqls = [];
3218                 foreach ( $conds as $cond ) {
3219                         $sqls[] = $this->selectSQLText(
3220                                 $table, $vars, $cond + $extra_conds, $fname, $options, $join_conds
3221                         );
3222                 }
3223                 $sql = $this->unionQueries( $sqls, $all ) . $orderBy;
3224                 if ( $limit !== null ) {
3225                         $sql = $this->limitResult( $sql, $limit, $offset );
3226                 }
3227
3228                 return $sql;
3229         }
3230
3231         public function conditional( $cond, $trueVal, $falseVal ) {
3232                 if ( is_array( $cond ) ) {
3233                         $cond = $this->makeList( $cond, self::LIST_AND );
3234                 }
3235
3236                 return " (CASE WHEN $cond THEN $trueVal ELSE $falseVal END) ";
3237         }
3238
3239         public function strreplace( $orig, $old, $new ) {
3240                 return "REPLACE({$orig}, {$old}, {$new})";
3241         }
3242
3243         public function getServerUptime() {
3244                 return 0;
3245         }
3246
3247         public function wasDeadlock() {
3248                 return false;
3249         }
3250
3251         public function wasLockTimeout() {
3252                 return false;
3253         }
3254
3255         public function wasConnectionLoss() {
3256                 return $this->wasConnectionError( $this->lastErrno() );
3257         }
3258
3259         public function wasReadOnlyError() {
3260                 return false;
3261         }
3262
3263         public function wasErrorReissuable() {
3264                 return (
3265                         $this->wasDeadlock() ||
3266                         $this->wasLockTimeout() ||
3267                         $this->wasConnectionLoss()
3268                 );
3269         }
3270
3271         /**
3272          * Do not use this method outside of Database/DBError classes
3273          *
3274          * @param int|string $errno
3275          * @return bool Whether the given query error was a connection drop
3276          */
3277         public function wasConnectionError( $errno ) {
3278                 return false;
3279         }
3280
3281         /**
3282          * @return bool Whether it is safe to assume the given error only caused statement rollback
3283          * @note This is for backwards compatibility for callers catching DBError exceptions in
3284          *   order to ignore problems like duplicate key errors or foriegn key violations
3285          * @since 1.31
3286          */
3287         protected function wasKnownStatementRollbackError() {
3288                 return false; // don't know; it could have caused a transaction rollback
3289         }
3290
3291         public function deadlockLoop() {
3292                 $args = func_get_args();
3293                 $function = array_shift( $args );
3294                 $tries = self::DEADLOCK_TRIES;
3295
3296                 $this->begin( __METHOD__ );
3297
3298                 $retVal = null;
3299                 /** @var Exception $e */
3300                 $e = null;
3301                 do {
3302                         try {
3303                                 $retVal = $function( ...$args );
3304                                 break;
3305                         } catch ( DBQueryError $e ) {
3306                                 if ( $this->wasDeadlock() ) {
3307                                         // Retry after a randomized delay
3308                                         usleep( mt_rand( self::DEADLOCK_DELAY_MIN, self::DEADLOCK_DELAY_MAX ) );
3309                                 } else {
3310                                         // Throw the error back up
3311                                         throw $e;
3312                                 }
3313                         }
3314                 } while ( --$tries > 0 );
3315
3316                 if ( $tries <= 0 ) {
3317                         // Too many deadlocks; give up
3318                         $this->rollback( __METHOD__ );
3319                         throw $e;
3320                 } else {
3321                         $this->commit( __METHOD__ );
3322
3323                         return $retVal;
3324                 }
3325         }
3326
3327         public function masterPosWait( DBMasterPos $pos, $timeout ) {
3328                 # Real waits are implemented in the subclass.
3329                 return 0;
3330         }
3331
3332         public function getReplicaPos() {
3333                 # Stub
3334                 return false;
3335         }
3336
3337         public function getMasterPos() {
3338                 # Stub
3339                 return false;
3340         }
3341
3342         public function serverIsReadOnly() {
3343                 return false;
3344         }
3345
3346         final public function onTransactionResolution( callable $callback, $fname = __METHOD__ ) {
3347                 if ( !$this->trxLevel ) {
3348                         throw new DBUnexpectedError( $this, "No transaction is active." );
3349                 }
3350                 $this->trxEndCallbacks[] = [ $callback, $fname, $this->currentAtomicSectionId() ];
3351         }
3352
3353         final public function onTransactionCommitOrIdle( callable $callback, $fname = __METHOD__ ) {
3354                 if ( !$this->trxLevel && $this->getTransactionRoundId() ) {
3355                         // Start an implicit transaction similar to how query() does
3356                         $this->begin( __METHOD__, self::TRANSACTION_INTERNAL );
3357                         $this->trxAutomatic = true;
3358                 }
3359
3360                 $this->trxIdleCallbacks[] = [ $callback, $fname, $this->currentAtomicSectionId() ];
3361                 if ( !$this->trxLevel ) {
3362                         $this->runOnTransactionIdleCallbacks( self::TRIGGER_IDLE );
3363                 }
3364         }
3365
3366         final public function onTransactionIdle( callable $callback, $fname = __METHOD__ ) {
3367                 $this->onTransactionCommitOrIdle( $callback, $fname );
3368         }
3369
3370         final public function onTransactionPreCommitOrIdle( callable $callback, $fname = __METHOD__ ) {
3371                 if ( !$this->trxLevel && $this->getTransactionRoundId() ) {
3372                         // Start an implicit transaction similar to how query() does
3373                         $this->begin( __METHOD__, self::TRANSACTION_INTERNAL );
3374                         $this->trxAutomatic = true;
3375                 }
3376
3377                 if ( $this->trxLevel ) {
3378                         $this->trxPreCommitCallbacks[] = [ $callback, $fname, $this->currentAtomicSectionId() ];
3379                 } else {
3380                         // No transaction is active nor will start implicitly, so make one for this callback
3381                         $this->startAtomic( __METHOD__, self::ATOMIC_CANCELABLE );
3382                         try {
3383                                 $callback( $this );
3384                                 $this->endAtomic( __METHOD__ );
3385                         } catch ( Exception $e ) {
3386                                 $this->cancelAtomic( __METHOD__ );
3387                                 throw $e;
3388                         }
3389                 }
3390         }
3391
3392         /**
3393          * @return AtomicSectionIdentifier|null ID of the topmost atomic section level
3394          */
3395         private function currentAtomicSectionId() {
3396                 if ( $this->trxLevel && $this->trxAtomicLevels ) {
3397                         $levelInfo = end( $this->trxAtomicLevels );
3398
3399                         return $levelInfo[1];
3400                 }
3401
3402                 return null;
3403         }
3404
3405         /**
3406          * @param AtomicSectionIdentifier $old
3407          * @param AtomicSectionIdentifier $new
3408          */
3409         private function reassignCallbacksForSection(
3410                 AtomicSectionIdentifier $old, AtomicSectionIdentifier $new
3411         ) {
3412                 foreach ( $this->trxPreCommitCallbacks as $key => $info ) {
3413                         if ( $info[2] === $old ) {
3414                                 $this->trxPreCommitCallbacks[$key][2] = $new;
3415                         }
3416                 }
3417                 foreach ( $this->trxIdleCallbacks as $key => $info ) {
3418                         if ( $info[2] === $old ) {
3419                                 $this->trxIdleCallbacks[$key][2] = $new;
3420                         }
3421                 }
3422                 foreach ( $this->trxEndCallbacks as $key => $info ) {
3423                         if ( $info[2] === $old ) {
3424                                 $this->trxEndCallbacks[$key][2] = $new;
3425                         }
3426                 }
3427         }
3428
3429         /**
3430          * @param AtomicSectionIdentifier[] $sectionIds ID of an actual savepoint
3431          * @throws UnexpectedValueException
3432          */
3433         private function modifyCallbacksForCancel( array $sectionIds ) {
3434                 // Cancel the "on commit" callbacks owned by this savepoint
3435                 $this->trxIdleCallbacks = array_filter(
3436                         $this->trxIdleCallbacks,
3437                         function ( $entry ) use ( $sectionIds ) {
3438                                 return !in_array( $entry[2], $sectionIds, true );
3439                         }
3440                 );
3441                 $this->trxPreCommitCallbacks = array_filter(
3442                         $this->trxPreCommitCallbacks,
3443                         function ( $entry ) use ( $sectionIds ) {
3444                                 return !in_array( $entry[2], $sectionIds, true );
3445                         }
3446                 );
3447                 // Make "on resolution" callbacks owned by this savepoint to perceive a rollback
3448                 foreach ( $this->trxEndCallbacks as $key => $entry ) {
3449                         if ( in_array( $entry[2], $sectionIds, true ) ) {
3450                                 $callback = $entry[0];
3451                                 $this->trxEndCallbacks[$key][0] = function () use ( $callback ) {
3452                                         return $callback( self::TRIGGER_ROLLBACK, $this );
3453                                 };
3454                         }
3455                 }
3456         }
3457
3458         final public function setTransactionListener( $name, callable $callback = null ) {
3459                 if ( $callback ) {
3460                         $this->trxRecurringCallbacks[$name] = $callback;
3461                 } else {
3462                         unset( $this->trxRecurringCallbacks[$name] );
3463                 }
3464         }
3465
3466         /**
3467          * Whether to disable running of post-COMMIT/ROLLBACK callbacks
3468          *
3469          * This method should not be used outside of Database/LoadBalancer
3470          *
3471          * @param bool $suppress
3472          * @since 1.28
3473          */
3474         final public function setTrxEndCallbackSuppression( $suppress ) {
3475                 $this->trxEndCallbacksSuppressed = $suppress;
3476         }
3477
3478         /**
3479          * Actually consume and run any "on transaction idle/resolution" callbacks.
3480          *
3481          * This method should not be used outside of Database/LoadBalancer
3482          *
3483          * @param int $trigger IDatabase::TRIGGER_* constant
3484          * @return int Number of callbacks attempted
3485          * @since 1.20
3486          * @throws Exception
3487          */
3488         public function runOnTransactionIdleCallbacks( $trigger ) {
3489                 if ( $this->trxLevel ) { // sanity
3490                         throw new DBUnexpectedError( $this, __METHOD__ . ': a transaction is still open.' );
3491                 }
3492
3493                 if ( $this->trxEndCallbacksSuppressed ) {
3494                         return 0;
3495                 }
3496
3497                 $count = 0;
3498                 $autoTrx = $this->getFlag( self::DBO_TRX ); // automatic begin() enabled?
3499                 /** @var Exception $e */
3500                 $e = null; // first exception
3501                 do { // callbacks may add callbacks :)
3502                         $callbacks = array_merge(
3503                                 $this->trxIdleCallbacks,
3504                                 $this->trxEndCallbacks // include "transaction resolution" callbacks
3505                         );
3506                         $this->trxIdleCallbacks = []; // consumed (and recursion guard)
3507                         $this->trxEndCallbacks = []; // consumed (recursion guard)
3508                         foreach ( $callbacks as $callback ) {
3509                                 ++$count;
3510                                 list( $phpCallback ) = $callback;
3511                                 $this->clearFlag( self::DBO_TRX ); // make each query its own transaction
3512                                 try {
3513                                         call_user_func( $phpCallback, $trigger, $this );
3514                                 } catch ( Exception $ex ) {
3515                                         call_user_func( $this->errorLogger, $ex );
3516                                         $e = $e ?: $ex;
3517                                         // Some callbacks may use startAtomic/endAtomic, so make sure
3518                                         // their transactions are ended so other callbacks don't fail
3519                                         if ( $this->trxLevel() ) {
3520                                                 $this->rollback( __METHOD__, self::FLUSHING_INTERNAL );
3521                                         }
3522                                 } finally {
3523                                         if ( $autoTrx ) {
3524                                                 $this->setFlag( self::DBO_TRX ); // restore automatic begin()
3525                                         } else {
3526                                                 $this->clearFlag( self::DBO_TRX ); // restore auto-commit
3527                                         }
3528                                 }
3529                         }
3530                 } while ( count( $this->trxIdleCallbacks ) );
3531
3532                 if ( $e instanceof Exception ) {
3533                         throw $e; // re-throw any first exception
3534                 }
3535
3536                 return $count;
3537         }
3538
3539         /**
3540          * Actually consume and run any "on transaction pre-commit" callbacks.
3541          *
3542          * This method should not be used outside of Database/LoadBalancer
3543          *
3544          * @since 1.22
3545          * @return int Number of callbacks attempted
3546          * @throws Exception
3547          */
3548         public function runOnTransactionPreCommitCallbacks() {
3549                 $count = 0;
3550
3551                 $e = null; // first exception
3552                 do { // callbacks may add callbacks :)
3553                         $callbacks = $this->trxPreCommitCallbacks;
3554                         $this->trxPreCommitCallbacks = []; // consumed (and recursion guard)
3555                         foreach ( $callbacks as $callback ) {
3556                                 try {
3557                                         ++$count;
3558                                         list( $phpCallback ) = $callback;
3559                                         $phpCallback( $this );
3560                                 } catch ( Exception $ex ) {
3561                                         ( $this->errorLogger )( $ex );
3562                                         $e = $e ?: $ex;
3563                                 }
3564                         }
3565                 } while ( count( $this->trxPreCommitCallbacks ) );
3566
3567                 if ( $e instanceof Exception ) {
3568                         throw $e; // re-throw any first exception
3569                 }
3570
3571                 return $count;
3572         }
3573
3574         /**
3575          * Actually run any "transaction listener" callbacks.
3576          *
3577          * This method should not be used outside of Database/LoadBalancer
3578          *
3579          * @param int $trigger IDatabase::TRIGGER_* constant
3580          * @throws Exception
3581          * @since 1.20
3582          */
3583         public function runTransactionListenerCallbacks( $trigger ) {
3584                 if ( $this->trxEndCallbacksSuppressed ) {
3585                         return;
3586                 }
3587
3588                 /** @var Exception $e */
3589                 $e = null; // first exception
3590
3591                 foreach ( $this->trxRecurringCallbacks as $phpCallback ) {
3592                         try {
3593                                 $phpCallback( $trigger, $this );
3594                         } catch ( Exception $ex ) {
3595                                 ( $this->errorLogger )( $ex );
3596                                 $e = $e ?: $ex;
3597                         }
3598                 }
3599
3600                 if ( $e instanceof Exception ) {
3601                         throw $e; // re-throw any first exception
3602                 }
3603         }
3604
3605         /**
3606          * Create a savepoint
3607          *
3608          * This is used internally to implement atomic sections. It should not be
3609          * used otherwise.
3610          *
3611          * @since 1.31
3612          * @param string $identifier Identifier for the savepoint
3613          * @param string $fname Calling function name
3614          */
3615         protected function doSavepoint( $identifier, $fname ) {
3616                 $this->query( 'SAVEPOINT ' . $this->addIdentifierQuotes( $identifier ), $fname );
3617         }
3618
3619         /**
3620          * Release a savepoint
3621          *
3622          * This is used internally to implement atomic sections. It should not be
3623          * used otherwise.
3624          *
3625          * @since 1.31
3626          * @param string $identifier Identifier for the savepoint
3627          * @param string $fname Calling function name
3628          */
3629         protected function doReleaseSavepoint( $identifier, $fname ) {
3630                 $this->query( 'RELEASE SAVEPOINT ' . $this->addIdentifierQuotes( $identifier ), $fname );
3631         }
3632
3633         /**
3634          * Rollback to a savepoint
3635          *
3636          * This is used internally to implement atomic sections. It should not be
3637          * used otherwise.
3638          *
3639          * @since 1.31
3640          * @param string $identifier Identifier for the savepoint
3641          * @param string $fname Calling function name
3642          */
3643         protected function doRollbackToSavepoint( $identifier, $fname ) {
3644                 $this->query( 'ROLLBACK TO SAVEPOINT ' . $this->addIdentifierQuotes( $identifier ), $fname );
3645         }
3646
3647         /**
3648          * @param string $fname
3649          * @return string
3650          */
3651         private function nextSavepointId( $fname ) {
3652                 $savepointId = self::$SAVEPOINT_PREFIX . ++$this->trxAtomicCounter;
3653                 if ( strlen( $savepointId ) > 30 ) {
3654                         // 30 == Oracle's identifier length limit (pre 12c)
3655                         // With a 22 character prefix, that puts the highest number at 99999999.
3656                         throw new DBUnexpectedError(
3657                                 $this,
3658                                 'There have been an excessively large number of atomic sections in a transaction'
3659                                 . " started by $this->trxFname (at $fname)"
3660                         );
3661                 }
3662
3663                 return $savepointId;
3664         }
3665
3666         final public function startAtomic(
3667                 $fname = __METHOD__, $cancelable = self::ATOMIC_NOT_CANCELABLE
3668         ) {
3669                 $savepointId = $cancelable === self::ATOMIC_CANCELABLE ? self::$NOT_APPLICABLE : null;
3670
3671                 if ( !$this->trxLevel ) {
3672                         $this->begin( $fname, self::TRANSACTION_INTERNAL ); // sets trxAutomatic
3673                         // If DBO_TRX is set, a series of startAtomic/endAtomic pairs will result
3674                         // in all changes being in one transaction to keep requests transactional.
3675                         if ( $this->getFlag( self::DBO_TRX ) ) {
3676                                 // Since writes could happen in between the topmost atomic sections as part
3677                                 // of the transaction, those sections will need savepoints.
3678                                 $savepointId = $this->nextSavepointId( $fname );
3679                                 $this->doSavepoint( $savepointId, $fname );
3680                         } else {
3681                                 $this->trxAutomaticAtomic = true;
3682                         }
3683                 } elseif ( $cancelable === self::ATOMIC_CANCELABLE ) {
3684                         $savepointId = $this->nextSavepointId( $fname );
3685                         $this->doSavepoint( $savepointId, $fname );
3686                 }
3687
3688                 $sectionId = new AtomicSectionIdentifier;
3689                 $this->trxAtomicLevels[] = [ $fname, $sectionId, $savepointId ];
3690                 $this->queryLogger->debug( 'startAtomic: entering level ' .
3691                         ( count( $this->trxAtomicLevels ) - 1 ) . " ($fname)" );
3692
3693                 return $sectionId;
3694         }
3695
3696         final public function endAtomic( $fname = __METHOD__ ) {
3697                 if ( !$this->trxLevel || !$this->trxAtomicLevels ) {
3698                         throw new DBUnexpectedError( $this, "No atomic section is open (got $fname)." );
3699                 }
3700
3701                 // Check if the current section matches $fname
3702                 $pos = count( $this->trxAtomicLevels ) - 1;
3703                 list( $savedFname, $sectionId, $savepointId ) = $this->trxAtomicLevels[$pos];
3704                 $this->queryLogger->debug( "endAtomic: leaving level $pos ($fname)" );
3705
3706                 if ( $savedFname !== $fname ) {
3707                         throw new DBUnexpectedError(
3708                                 $this,
3709                                 "Invalid atomic section ended (got $fname but expected $savedFname)."
3710                         );
3711                 }
3712
3713                 // Remove the last section (no need to re-index the array)
3714                 array_pop( $this->trxAtomicLevels );
3715
3716                 if ( !$this->trxAtomicLevels && $this->trxAutomaticAtomic ) {
3717                         $this->commit( $fname, self::FLUSHING_INTERNAL );
3718                 } elseif ( $savepointId !== null && $savepointId !== self::$NOT_APPLICABLE ) {
3719                         $this->doReleaseSavepoint( $savepointId, $fname );
3720                 }
3721
3722                 // Hoist callback ownership for callbacks in the section that just ended;
3723                 // all callbacks should have an owner that is present in trxAtomicLevels.
3724                 $currentSectionId = $this->currentAtomicSectionId();
3725                 if ( $currentSectionId ) {
3726                         $this->reassignCallbacksForSection( $sectionId, $currentSectionId );
3727                 }
3728         }
3729
3730         final public function cancelAtomic(
3731                 $fname = __METHOD__, AtomicSectionIdentifier $sectionId = null
3732         ) {
3733                 if ( !$this->trxLevel || !$this->trxAtomicLevels ) {
3734                         throw new DBUnexpectedError( $this, "No atomic section is open (got $fname)." );
3735                 }
3736
3737                 $excisedFnames = [];
3738                 if ( $sectionId !== null ) {
3739                         // Find the (last) section with the given $sectionId
3740                         $pos = -1;
3741                         foreach ( $this->trxAtomicLevels as $i => list( $asFname, $asId, $spId ) ) {
3742                                 if ( $asId === $sectionId ) {
3743                                         $pos = $i;
3744                                 }
3745                         }
3746                         if ( $pos < 0 ) {
3747                                 throw new DBUnexpectedError( $this, "Atomic section not found (for $fname)" );
3748                         }
3749                         // Remove all descendant sections and re-index the array
3750                         $excisedIds = [];
3751                         $len = count( $this->trxAtomicLevels );
3752                         for ( $i = $pos + 1; $i < $len; ++$i ) {
3753                                 $excisedFnames[] = $this->trxAtomicLevels[$i][0];
3754                                 $excisedIds[] = $this->trxAtomicLevels[$i][1];
3755                         }
3756                         $this->trxAtomicLevels = array_slice( $this->trxAtomicLevels, 0, $pos + 1 );
3757                         $this->modifyCallbacksForCancel( $excisedIds );
3758                 }
3759
3760                 // Check if the current section matches $fname
3761                 $pos = count( $this->trxAtomicLevels ) - 1;
3762                 list( $savedFname, $savedSectionId, $savepointId ) = $this->trxAtomicLevels[$pos];
3763
3764                 if ( $excisedFnames ) {
3765                         $this->queryLogger->debug( "cancelAtomic: canceling level $pos ($savedFname) " .
3766                                 "and descendants " . implode( ', ', $excisedFnames ) );
3767                 } else {
3768                         $this->queryLogger->debug( "cancelAtomic: canceling level $pos ($savedFname)" );
3769                 }
3770
3771                 if ( $savedFname !== $fname ) {
3772                         throw new DBUnexpectedError(
3773                                 $this,
3774                                 "Invalid atomic section ended (got $fname but expected $savedFname)."
3775                         );
3776                 }
3777
3778                 // Remove the last section (no need to re-index the array)
3779                 array_pop( $this->trxAtomicLevels );
3780                 $this->modifyCallbacksForCancel( [ $savedSectionId ] );
3781
3782                 if ( $savepointId !== null ) {
3783                         // Rollback the transaction to the state just before this atomic section
3784                         if ( $savepointId === self::$NOT_APPLICABLE ) {
3785                                 $this->rollback( $fname, self::FLUSHING_INTERNAL );
3786                         } else {
3787                                 $this->doRollbackToSavepoint( $savepointId, $fname );
3788                                 $this->trxStatus = self::STATUS_TRX_OK; // no exception; recovered
3789                                 $this->trxStatusIgnoredCause = null;
3790                         }
3791                 } elseif ( $this->trxStatus > self::STATUS_TRX_ERROR ) {
3792                         // Put the transaction into an error state if it's not already in one
3793                         $this->trxStatus = self::STATUS_TRX_ERROR;
3794                         $this->trxStatusCause = new DBUnexpectedError(
3795                                 $this,
3796                                 "Uncancelable atomic section canceled (got $fname)."
3797                         );
3798                 }
3799
3800                 $this->affectedRowCount = 0; // for the sake of consistency
3801         }
3802
3803         final public function doAtomicSection(
3804                 $fname, callable $callback, $cancelable = self::ATOMIC_NOT_CANCELABLE
3805         ) {
3806                 $sectionId = $this->startAtomic( $fname, $cancelable );
3807                 try {
3808                         $res = $callback( $this, $fname );
3809                 } catch ( Exception $e ) {
3810                         $this->cancelAtomic( $fname, $sectionId );
3811
3812                         throw $e;
3813                 }
3814                 $this->endAtomic( $fname );
3815
3816                 return $res;
3817         }
3818
3819         final public function begin( $fname = __METHOD__, $mode = self::TRANSACTION_EXPLICIT ) {
3820                 static $modes = [ self::TRANSACTION_EXPLICIT, self::TRANSACTION_INTERNAL ];
3821                 if ( !in_array( $mode, $modes, true ) ) {
3822                         throw new DBUnexpectedError( $this, "$fname: invalid mode parameter '$mode'." );
3823                 }
3824
3825                 // Protect against mismatched atomic section, transaction nesting, and snapshot loss
3826                 if ( $this->trxLevel ) {
3827                         if ( $this->trxAtomicLevels ) {
3828                                 $levels = $this->flatAtomicSectionList();
3829                                 $msg = "$fname: Got explicit BEGIN while atomic section(s) $levels are open.";
3830                                 throw new DBUnexpectedError( $this, $msg );
3831                         } elseif ( !$this->trxAutomatic ) {
3832                                 $msg = "$fname: Explicit transaction already active (from {$this->trxFname}).";
3833                                 throw new DBUnexpectedError( $this, $msg );
3834                         } else {
3835                                 $msg = "$fname: Implicit transaction already active (from {$this->trxFname}).";
3836                                 throw new DBUnexpectedError( $this, $msg );
3837                         }
3838                 } elseif ( $this->getFlag( self::DBO_TRX ) && $mode !== self::TRANSACTION_INTERNAL ) {
3839                         $msg = "$fname: Implicit transaction expected (DBO_TRX set).";
3840                         throw new DBUnexpectedError( $this, $msg );
3841                 }
3842
3843                 // Avoid fatals if close() was called
3844                 $this->assertOpen();
3845
3846                 $this->doBegin( $fname );
3847                 $this->trxStatus = self::STATUS_TRX_OK;
3848                 $this->trxStatusIgnoredCause = null;
3849                 $this->trxAtomicCounter = 0;
3850                 $this->trxTimestamp = microtime( true );
3851                 $this->trxFname = $fname;
3852                 $this->trxDoneWrites = false;
3853                 $this->trxAutomaticAtomic = false;
3854                 $this->trxAtomicLevels = [];
3855                 $this->trxShortId = sprintf( '%06x', mt_rand( 0, 0xffffff ) );
3856                 $this->trxWriteDuration = 0.0;
3857                 $this->trxWriteQueryCount = 0;
3858                 $this->trxWriteAffectedRows = 0;
3859                 $this->trxWriteAdjDuration = 0.0;
3860                 $this->trxWriteAdjQueryCount = 0;
3861                 $this->trxWriteCallers = [];
3862                 // First SELECT after BEGIN will establish the snapshot in REPEATABLE-READ.
3863                 // Get an estimate of the replication lag before any such queries.
3864                 $this->trxReplicaLag = null; // clear cached value first
3865                 $this->trxReplicaLag = $this->getApproximateLagStatus()['lag'];
3866                 // T147697: make explicitTrxActive() return true until begin() finishes. This way, no
3867                 // caller will think its OK to muck around with the transaction just because startAtomic()
3868                 // has not yet completed (e.g. setting trxAtomicLevels).
3869                 $this->trxAutomatic = ( $mode === self::TRANSACTION_INTERNAL );
3870         }
3871
3872         /**
3873          * Issues the BEGIN command to the database server.
3874          *
3875          * @see Database::begin()
3876          * @param string $fname
3877          */
3878         protected function doBegin( $fname ) {
3879                 $this->query( 'BEGIN', $fname );
3880                 $this->trxLevel = 1;
3881         }
3882
3883         final public function commit( $fname = __METHOD__, $flush = self::FLUSHING_ONE ) {
3884                 static $modes = [ self::FLUSHING_ONE, self::FLUSHING_ALL_PEERS, self::FLUSHING_INTERNAL ];
3885                 if ( !in_array( $flush, $modes, true ) ) {
3886                         throw new DBUnexpectedError( $this, "$fname: invalid flush parameter '$flush'." );
3887                 }
3888
3889                 if ( $this->trxLevel && $this->trxAtomicLevels ) {
3890                         // There are still atomic sections open; this cannot be ignored
3891                         $levels = $this->flatAtomicSectionList();
3892                         throw new DBUnexpectedError(
3893                                 $this,
3894                                 "$fname: Got COMMIT while atomic sections $levels are still open."
3895                         );
3896                 }
3897
3898                 if ( $flush === self::FLUSHING_INTERNAL || $flush === self::FLUSHING_ALL_PEERS ) {
3899                         if ( !$this->trxLevel ) {
3900                                 return; // nothing to do
3901                         } elseif ( !$this->trxAutomatic ) {
3902                                 throw new DBUnexpectedError(
3903                                         $this,
3904                                         "$fname: Flushing an explicit transaction, getting out of sync."
3905                                 );
3906                         }
3907                 } else {
3908                         if ( !$this->trxLevel ) {
3909                                 $this->queryLogger->error(
3910                                         "$fname: No transaction to commit, something got out of sync." );
3911                                 return; // nothing to do
3912                         } elseif ( $this->trxAutomatic ) {
3913                                 throw new DBUnexpectedError(
3914                                         $this,
3915                                         "$fname: Expected mass commit of all peer transactions (DBO_TRX set)."
3916                                 );
3917                         }
3918                 }
3919
3920                 // Avoid fatals if close() was called
3921                 $this->assertOpen();
3922
3923                 $this->runOnTransactionPreCommitCallbacks();
3924
3925                 $writeTime = $this->pendingWriteQueryDuration( self::ESTIMATE_DB_APPLY );
3926                 $this->doCommit( $fname );
3927                 $this->trxStatus = self::STATUS_TRX_NONE;
3928
3929                 if ( $this->trxDoneWrites ) {
3930                         $this->lastWriteTime = microtime( true );
3931                         $this->trxProfiler->transactionWritingOut(
3932                                 $this->server,
3933                                 $this->getDomainID(),
3934                                 $this->trxShortId,
3935                                 $writeTime,
3936                                 $this->trxWriteAffectedRows
3937                         );
3938                 }
3939
3940                 // With FLUSHING_ALL_PEERS, callbacks will be explicitly run later
3941                 if ( $flush !== self::FLUSHING_ALL_PEERS ) {
3942                         $this->runOnTransactionIdleCallbacks( self::TRIGGER_COMMIT );
3943                         $this->runTransactionListenerCallbacks( self::TRIGGER_COMMIT );
3944                 }
3945         }
3946
3947         /**
3948          * Issues the COMMIT command to the database server.
3949          *
3950          * @see Database::commit()
3951          * @param string $fname
3952          */
3953         protected function doCommit( $fname ) {
3954                 if ( $this->trxLevel ) {
3955                         $this->query( 'COMMIT', $fname );
3956                         $this->trxLevel = 0;
3957                 }
3958         }
3959
3960         final public function rollback( $fname = __METHOD__, $flush = '' ) {
3961                 $trxActive = $this->trxLevel;
3962
3963                 if ( $flush !== self::FLUSHING_INTERNAL && $flush !== self::FLUSHING_ALL_PEERS ) {
3964                         if ( $this->getFlag( self::DBO_TRX ) ) {
3965                                 throw new DBUnexpectedError(
3966                                         $this,
3967                                         "$fname: Expected mass rollback of all peer transactions (DBO_TRX set)."
3968                                 );
3969                         }
3970                 }
3971
3972                 if ( $trxActive ) {
3973                         // Avoid fatals if close() was called
3974                         $this->assertOpen();
3975
3976                         $this->doRollback( $fname );
3977                         $this->trxStatus = self::STATUS_TRX_NONE;
3978                         $this->trxAtomicLevels = [];
3979                         // Estimate the RTT via a query now that trxStatus is OK
3980                         $writeTime = $this->pingAndCalculateLastTrxApplyTime();
3981
3982                         if ( $this->trxDoneWrites ) {
3983                                 $this->trxProfiler->transactionWritingOut(
3984                                         $this->server,
3985                                         $this->getDomainID(),
3986                                         $this->trxShortId,
3987                                         $writeTime,
3988                                         $this->trxWriteAffectedRows
3989                                 );
3990                         }
3991                 }
3992
3993                 // Clear any commit-dependant callbacks. They might even be present
3994                 // only due to transaction rounds, with no SQL transaction being active
3995                 $this->trxIdleCallbacks = [];
3996                 $this->trxPreCommitCallbacks = [];
3997
3998                 // With FLUSHING_ALL_PEERS, callbacks will be explicitly run later
3999                 if ( $trxActive && $flush !== self::FLUSHING_ALL_PEERS ) {
4000                         try {
4001                                 $this->runOnTransactionIdleCallbacks( self::TRIGGER_ROLLBACK );
4002                         } catch ( Exception $e ) {
4003                                 // already logged; finish and let LoadBalancer move on during mass-rollback
4004                         }
4005                         try {
4006                                 $this->runTransactionListenerCallbacks( self::TRIGGER_ROLLBACK );
4007                         } catch ( Exception $e ) {
4008                                 // already logged; let LoadBalancer move on during mass-rollback
4009                         }
4010
4011                         $this->affectedRowCount = 0; // for the sake of consistency
4012                 }
4013         }
4014
4015         /**
4016          * Issues the ROLLBACK command to the database server.
4017          *
4018          * @see Database::rollback()
4019          * @param string $fname
4020          */
4021         protected function doRollback( $fname ) {
4022                 if ( $this->trxLevel ) {
4023                         # Disconnects cause rollback anyway, so ignore those errors
4024                         $ignoreErrors = true;
4025                         $this->query( 'ROLLBACK', $fname, $ignoreErrors );
4026                         $this->trxLevel = 0;
4027                 }
4028         }
4029
4030         public function flushSnapshot( $fname = __METHOD__ ) {
4031                 if ( $this->writesOrCallbacksPending() || $this->explicitTrxActive() ) {
4032                         // This only flushes transactions to clear snapshots, not to write data
4033                         $fnames = implode( ', ', $this->pendingWriteAndCallbackCallers() );
4034                         throw new DBUnexpectedError(
4035                                 $this,
4036                                 "$fname: Cannot flush snapshot because writes are pending ($fnames)."
4037                         );
4038                 }
4039
4040                 $this->commit( $fname, self::FLUSHING_INTERNAL );
4041         }
4042
4043         public function explicitTrxActive() {
4044                 return $this->trxLevel && ( $this->trxAtomicLevels || !$this->trxAutomatic );
4045         }
4046
4047         public function duplicateTableStructure(
4048                 $oldName, $newName, $temporary = false, $fname = __METHOD__
4049         ) {
4050                 throw new RuntimeException( __METHOD__ . ' is not implemented in descendant class' );
4051         }
4052
4053         public function listTables( $prefix = null, $fname = __METHOD__ ) {
4054                 throw new RuntimeException( __METHOD__ . ' is not implemented in descendant class' );
4055         }
4056
4057         public function listViews( $prefix = null, $fname = __METHOD__ ) {
4058                 throw new RuntimeException( __METHOD__ . ' is not implemented in descendant class' );
4059         }
4060
4061         public function timestamp( $ts = 0 ) {
4062                 $t = new ConvertibleTimestamp( $ts );
4063                 // Let errors bubble up to avoid putting garbage in the DB
4064                 return $t->getTimestamp( TS_MW );
4065         }
4066
4067         public function timestampOrNull( $ts = null ) {
4068                 if ( is_null( $ts ) ) {
4069                         return null;
4070                 } else {
4071                         return $this->timestamp( $ts );
4072                 }
4073         }
4074
4075         public function affectedRows() {
4076                 return ( $this->affectedRowCount === null )
4077                         ? $this->fetchAffectedRowCount() // default to driver value
4078                         : $this->affectedRowCount;
4079         }
4080
4081         /**
4082          * @return int Number of retrieved rows according to the driver
4083          */
4084         abstract protected function fetchAffectedRowCount();
4085
4086         /**
4087          * Take the result from a query, and wrap it in a ResultWrapper if
4088          * necessary. Boolean values are passed through as is, to indicate success
4089          * of write queries or failure.
4090          *
4091          * Once upon a time, Database::query() returned a bare MySQL result
4092          * resource, and it was necessary to call this function to convert it to
4093          * a wrapper. Nowadays, raw database objects are never exposed to external
4094          * callers, so this is unnecessary in external code.
4095          *
4096          * @param bool|ResultWrapper|resource $result
4097          * @return bool|ResultWrapper
4098          */
4099         protected function resultObject( $result ) {
4100                 if ( !$result ) {
4101                         return false;
4102                 } elseif ( $result instanceof ResultWrapper ) {
4103                         return $result;
4104                 } elseif ( $result === true ) {
4105                         // Successful write query
4106                         return $result;
4107                 } else {
4108                         return new ResultWrapper( $this, $result );
4109                 }
4110         }
4111
4112         public function ping( &$rtt = null ) {
4113                 // Avoid hitting the server if it was hit recently
4114                 if ( $this->isOpen() && ( microtime( true ) - $this->lastPing ) < self::PING_TTL ) {
4115                         if ( !func_num_args() || $this->rttEstimate > 0 ) {
4116                                 $rtt = $this->rttEstimate;
4117                                 return true; // don't care about $rtt
4118                         }
4119                 }
4120
4121                 // This will reconnect if possible or return false if not
4122                 $this->clearFlag( self::DBO_TRX, self::REMEMBER_PRIOR );
4123                 $ok = ( $this->query( self::PING_QUERY, __METHOD__, true ) !== false );
4124                 $this->restoreFlags( self::RESTORE_PRIOR );
4125
4126                 if ( $ok ) {
4127                         $rtt = $this->rttEstimate;
4128                 }
4129
4130                 return $ok;
4131         }
4132
4133         /**
4134          * Close any existing (dead) database connection and open a new connection
4135          *
4136          * @param string $fname
4137          * @return bool True if new connection is opened successfully, false if error
4138          */
4139         protected function replaceLostConnection( $fname ) {
4140                 $this->closeConnection();
4141                 $this->opened = false;
4142                 $this->conn = false;
4143                 try {
4144                         $this->open(
4145                                 $this->server,
4146                                 $this->user,
4147                                 $this->password,
4148                                 $this->getDBname(),
4149                                 $this->dbSchema(),
4150                                 $this->tablePrefix()
4151                         );
4152                         $this->lastPing = microtime( true );
4153                         $ok = true;
4154
4155                         $this->connLogger->warning(
4156                                 $fname . ': lost connection to {dbserver}; reconnected',
4157                                 [
4158                                         'dbserver' => $this->getServer(),
4159                                         'trace' => ( new RuntimeException() )->getTraceAsString()
4160                                 ]
4161                         );
4162                 } catch ( DBConnectionError $e ) {
4163                         $ok = false;
4164
4165                         $this->connLogger->error(
4166                                 $fname . ': lost connection to {dbserver} permanently',
4167                                 [ 'dbserver' => $this->getServer() ]
4168                         );
4169                 }
4170
4171                 $this->handleSessionLoss();
4172
4173                 return $ok;
4174         }
4175
4176         public function getSessionLagStatus() {
4177                 return $this->getRecordedTransactionLagStatus() ?: $this->getApproximateLagStatus();
4178         }
4179
4180         /**
4181          * Get the replica DB lag when the current transaction started
4182          *
4183          * This is useful when transactions might use snapshot isolation
4184          * (e.g. REPEATABLE-READ in innodb), so the "real" lag of that data
4185          * is this lag plus transaction duration. If they don't, it is still
4186          * safe to be pessimistic. This returns null if there is no transaction.
4187          *
4188          * This returns null if the lag status for this transaction was not yet recorded.
4189          *
4190          * @return array|null ('lag': seconds or false on error, 'since': UNIX timestamp of BEGIN)
4191          * @since 1.27
4192          */
4193         final protected function getRecordedTransactionLagStatus() {
4194                 return ( $this->trxLevel && $this->trxReplicaLag !== null )
4195                         ? [ 'lag' => $this->trxReplicaLag, 'since' => $this->trxTimestamp() ]
4196                         : null;
4197         }
4198
4199         /**
4200          * Get a replica DB lag estimate for this server
4201          *
4202          * @return array ('lag': seconds or false on error, 'since': UNIX timestamp of estimate)
4203          * @since 1.27
4204          */
4205         protected function getApproximateLagStatus() {
4206                 return [
4207                         'lag'   => $this->getLBInfo( 'replica' ) ? $this->getLag() : 0,
4208                         'since' => microtime( true )
4209                 ];
4210         }
4211
4212         /**
4213          * Merge the result of getSessionLagStatus() for several DBs
4214          * using the most pessimistic values to estimate the lag of
4215          * any data derived from them in combination
4216          *
4217          * This is information is useful for caching modules
4218          *
4219          * @see WANObjectCache::set()
4220          * @see WANObjectCache::getWithSetCallback()
4221          *
4222          * @param IDatabase $db1
4223          * @param IDatabase|null $db2 [optional]
4224          * @return array Map of values:
4225          *   - lag: highest lag of any of the DBs or false on error (e.g. replication stopped)
4226          *   - since: oldest UNIX timestamp of any of the DB lag estimates
4227          *   - pending: whether any of the DBs have uncommitted changes
4228          * @throws DBError
4229          * @since 1.27
4230          */
4231         public static function getCacheSetOptions( IDatabase $db1, IDatabase $db2 = null ) {
4232                 $res = [ 'lag' => 0, 'since' => INF, 'pending' => false ];
4233                 foreach ( func_get_args() as $db ) {
4234                         /** @var IDatabase $db */
4235                         $status = $db->getSessionLagStatus();
4236                         if ( $status['lag'] === false ) {
4237                                 $res['lag'] = false;
4238                         } elseif ( $res['lag'] !== false ) {
4239                                 $res['lag'] = max( $res['lag'], $status['lag'] );
4240                         }
4241                         $res['since'] = min( $res['since'], $status['since'] );
4242                         $res['pending'] = $res['pending'] ?: $db->writesPending();
4243                 }
4244
4245                 return $res;
4246         }
4247
4248         public function getLag() {
4249                 return 0;
4250         }
4251
4252         public function maxListLen() {
4253                 return 0;
4254         }
4255
4256         public function encodeBlob( $b ) {
4257                 return $b;
4258         }
4259
4260         public function decodeBlob( $b ) {
4261                 if ( $b instanceof Blob ) {
4262                         $b = $b->fetch();
4263                 }
4264                 return $b;
4265         }
4266
4267         public function setSessionOptions( array $options ) {
4268         }
4269
4270         public function sourceFile(
4271                 $filename,
4272                 callable $lineCallback = null,
4273                 callable $resultCallback = null,
4274                 $fname = false,
4275                 callable $inputCallback = null
4276         ) {
4277                 Wikimedia\suppressWarnings();
4278                 $fp = fopen( $filename, 'r' );
4279                 Wikimedia\restoreWarnings();
4280
4281                 if ( $fp === false ) {
4282                         throw new RuntimeException( "Could not open \"{$filename}\".\n" );
4283                 }
4284
4285                 if ( !$fname ) {
4286                         $fname = __METHOD__ . "( $filename )";
4287                 }
4288
4289                 try {
4290                         $error = $this->sourceStream(
4291                                 $fp, $lineCallback, $resultCallback, $fname, $inputCallback );
4292                 } catch ( Exception $e ) {
4293                         fclose( $fp );
4294                         throw $e;
4295                 }
4296
4297                 fclose( $fp );
4298
4299                 return $error;
4300         }
4301
4302         public function setSchemaVars( $vars ) {
4303                 $this->schemaVars = $vars;
4304         }
4305
4306         public function sourceStream(
4307                 $fp,
4308                 callable $lineCallback = null,
4309                 callable $resultCallback = null,
4310                 $fname = __METHOD__,
4311                 callable $inputCallback = null
4312         ) {
4313                 $delimiterReset = new ScopedCallback(
4314                         function ( $delimiter ) {
4315                                 $this->delimiter = $delimiter;
4316                         },
4317                         [ $this->delimiter ]
4318                 );
4319                 $cmd = '';
4320
4321                 while ( !feof( $fp ) ) {
4322                         if ( $lineCallback ) {
4323                                 call_user_func( $lineCallback );
4324                         }
4325
4326                         $line = trim( fgets( $fp ) );
4327
4328                         if ( $line == '' ) {
4329                                 continue;
4330                         }
4331
4332                         if ( $line[0] == '-' && $line[1] == '-' ) {
4333                                 continue;
4334                         }
4335
4336                         if ( $cmd != '' ) {
4337                                 $cmd .= ' ';
4338                         }
4339
4340                         $done = $this->streamStatementEnd( $cmd, $line );
4341
4342                         $cmd .= "$line\n";
4343
4344                         if ( $done || feof( $fp ) ) {
4345                                 $cmd = $this->replaceVars( $cmd );
4346
4347                                 if ( $inputCallback ) {
4348                                         $callbackResult = $inputCallback( $cmd );
4349
4350                                         if ( is_string( $callbackResult ) || !$callbackResult ) {
4351                                                 $cmd = $callbackResult;
4352                                         }
4353                                 }
4354
4355                                 if ( $cmd ) {
4356                                         $res = $this->query( $cmd, $fname );
4357
4358                                         if ( $resultCallback ) {
4359                                                 $resultCallback( $res, $this );
4360                                         }
4361
4362                                         if ( $res === false ) {
4363                                                 $err = $this->lastError();
4364
4365                                                 return "Query \"{$cmd}\" failed with error code \"$err\".\n";
4366                                         }
4367                                 }
4368                                 $cmd = '';
4369                         }
4370                 }
4371
4372                 ScopedCallback::consume( $delimiterReset );
4373                 return true;
4374         }
4375
4376         /**
4377          * Called by sourceStream() to check if we've reached a statement end
4378          *
4379          * @param string &$sql SQL assembled so far
4380          * @param string &$newLine New line about to be added to $sql
4381          * @return bool Whether $newLine contains end of the statement
4382          */
4383         public function streamStatementEnd( &$sql, &$newLine ) {
4384                 if ( $this->delimiter ) {
4385                         $prev = $newLine;
4386                         $newLine = preg_replace(
4387                                 '/' . preg_quote( $this->delimiter, '/' ) . '$/', '', $newLine );
4388                         if ( $newLine != $prev ) {
4389                                 return true;
4390                         }
4391                 }
4392
4393                 return false;
4394         }
4395
4396         /**
4397          * Database independent variable replacement. Replaces a set of variables
4398          * in an SQL statement with their contents as given by $this->getSchemaVars().
4399          *
4400          * Supports '{$var}' `{$var}` and / *$var* / (without the spaces) style variables.
4401          *
4402          * - '{$var}' should be used for text and is passed through the database's
4403          *   addQuotes method.
4404          * - `{$var}` should be used for identifiers (e.g. table and database names).
4405          *   It is passed through the database's addIdentifierQuotes method which
4406          *   can be overridden if the database uses something other than backticks.
4407          * - / *_* / or / *$wgDBprefix* / passes the name that follows through the
4408          *   database's tableName method.
4409          * - / *i* / passes the name that follows through the database's indexName method.
4410          * - In all other cases, / *$var* / is left unencoded. Except for table options,
4411          *   its use should be avoided. In 1.24 and older, string encoding was applied.
4412          *
4413          * @param string $ins SQL statement to replace variables in
4414          * @return string The new SQL statement with variables replaced
4415          */
4416         protected function replaceVars( $ins ) {
4417                 $vars = $this->getSchemaVars();
4418                 return preg_replace_callback(
4419                         '!
4420                                 /\* (\$wgDBprefix|[_i]) \*/ (\w*) | # 1-2. tableName, indexName
4421                                 \'\{\$ (\w+) }\'                  | # 3. addQuotes
4422                                 `\{\$ (\w+) }`                    | # 4. addIdentifierQuotes
4423                                 /\*\$ (\w+) \*/                     # 5. leave unencoded
4424                         !x',
4425                         function ( $m ) use ( $vars ) {
4426                                 // Note: Because of <https://bugs.php.net/bug.php?id=51881>,
4427                                 // check for both nonexistent keys *and* the empty string.
4428                                 if ( isset( $m[1] ) && $m[1] !== '' ) {
4429                                         if ( $m[1] === 'i' ) {
4430                                                 return $this->indexName( $m[2] );
4431                                         } else {
4432                                                 return $this->tableName( $m[2] );
4433                                         }
4434                                 } elseif ( isset( $m[3] ) && $m[3] !== '' && array_key_exists( $m[3], $vars ) ) {
4435                                         return $this->addQuotes( $vars[$m[3]] );
4436                                 } elseif ( isset( $m[4] ) && $m[4] !== '' && array_key_exists( $m[4], $vars ) ) {
4437                                         return $this->addIdentifierQuotes( $vars[$m[4]] );
4438                                 } elseif ( isset( $m[5] ) && $m[5] !== '' && array_key_exists( $m[5], $vars ) ) {
4439                                         return $vars[$m[5]];
4440                                 } else {
4441                                         return $m[0];
4442                                 }
4443                         },
4444                         $ins
4445                 );
4446         }
4447
4448         /**
4449          * Get schema variables. If none have been set via setSchemaVars(), then
4450          * use some defaults from the current object.
4451          *
4452          * @return array
4453          */
4454         protected function getSchemaVars() {
4455                 if ( $this->schemaVars ) {
4456                         return $this->schemaVars;
4457                 } else {
4458                         return $this->getDefaultSchemaVars();
4459                 }
4460         }
4461
4462         /**
4463          * Get schema variables to use if none have been set via setSchemaVars().
4464          *
4465          * Override this in derived classes to provide variables for tables.sql
4466          * and SQL patch files.
4467          *
4468          * @return array
4469          */
4470         protected function getDefaultSchemaVars() {
4471                 return [];
4472         }
4473
4474         public function lockIsFree( $lockName, $method ) {
4475                 // RDBMs methods for checking named locks may or may not count this thread itself.
4476                 // In MySQL, IS_FREE_LOCK() returns 0 if the thread already has the lock. This is
4477                 // the behavior choosen by the interface for this method.
4478                 return !isset( $this->namedLocksHeld[$lockName] );
4479         }
4480
4481         public function lock( $lockName, $method, $timeout = 5 ) {
4482                 $this->namedLocksHeld[$lockName] = 1;
4483
4484                 return true;
4485         }
4486
4487         public function unlock( $lockName, $method ) {
4488                 unset( $this->namedLocksHeld[$lockName] );
4489
4490                 return true;
4491         }
4492
4493         public function getScopedLockAndFlush( $lockKey, $fname, $timeout ) {
4494                 if ( $this->writesOrCallbacksPending() ) {
4495                         // This only flushes transactions to clear snapshots, not to write data
4496                         $fnames = implode( ', ', $this->pendingWriteAndCallbackCallers() );
4497                         throw new DBUnexpectedError(
4498                                 $this,
4499                                 "$fname: Cannot flush pre-lock snapshot because writes are pending ($fnames)."
4500                         );
4501                 }
4502
4503                 if ( !$this->lock( $lockKey, $fname, $timeout ) ) {
4504                         return null;
4505                 }
4506
4507                 $unlocker = new ScopedCallback( function () use ( $lockKey, $fname ) {
4508                         if ( $this->trxLevel() ) {
4509                                 // There is a good chance an exception was thrown, causing any early return
4510                                 // from the caller. Let any error handler get a chance to issue rollback().
4511                                 // If there isn't one, let the error bubble up and trigger server-side rollback.
4512                                 $this->onTransactionResolution(
4513                                         function () use ( $lockKey, $fname ) {
4514                                                 $this->unlock( $lockKey, $fname );
4515                                         },
4516                                         $fname
4517                                 );
4518                         } else {
4519                                 $this->unlock( $lockKey, $fname );
4520                         }
4521                 } );
4522
4523                 $this->commit( $fname, self::FLUSHING_INTERNAL );
4524
4525                 return $unlocker;
4526         }
4527
4528         public function namedLocksEnqueue() {
4529                 return false;
4530         }
4531
4532         public function tableLocksHaveTransactionScope() {
4533                 return true;
4534         }
4535
4536         final public function lockTables( array $read, array $write, $method ) {
4537                 if ( $this->writesOrCallbacksPending() ) {
4538                         throw new DBUnexpectedError( $this, "Transaction writes or callbacks still pending." );
4539                 }
4540
4541                 if ( $this->tableLocksHaveTransactionScope() ) {
4542                         $this->startAtomic( $method );
4543                 }
4544
4545                 return $this->doLockTables( $read, $write, $method );
4546         }
4547
4548         /**
4549          * Helper function for lockTables() that handles the actual table locking
4550          *
4551          * @param array $read Array of tables to lock for read access
4552          * @param array $write Array of tables to lock for write access
4553          * @param string $method Name of caller
4554          * @return true
4555          */
4556         protected function doLockTables( array $read, array $write, $method ) {
4557                 return true;
4558         }
4559
4560         final public function unlockTables( $method ) {
4561                 if ( $this->tableLocksHaveTransactionScope() ) {
4562                         $this->endAtomic( $method );
4563
4564                         return true; // locks released on COMMIT/ROLLBACK
4565                 }
4566
4567                 return $this->doUnlockTables( $method );
4568         }
4569
4570         /**
4571          * Helper function for unlockTables() that handles the actual table unlocking
4572          *
4573          * @param string $method Name of caller
4574          * @return true
4575          */
4576         protected function doUnlockTables( $method ) {
4577                 return true;
4578         }
4579
4580         /**
4581          * Delete a table
4582          * @param string $tableName
4583          * @param string $fName
4584          * @return bool|ResultWrapper
4585          * @since 1.18
4586          */
4587         public function dropTable( $tableName, $fName = __METHOD__ ) {
4588                 if ( !$this->tableExists( $tableName, $fName ) ) {
4589                         return false;
4590                 }
4591                 $sql = "DROP TABLE " . $this->tableName( $tableName ) . " CASCADE";
4592
4593                 return $this->query( $sql, $fName );
4594         }
4595
4596         public function getInfinity() {
4597                 return 'infinity';
4598         }
4599
4600         public function encodeExpiry( $expiry ) {
4601                 return ( $expiry == '' || $expiry == 'infinity' || $expiry == $this->getInfinity() )
4602                         ? $this->getInfinity()
4603                         : $this->timestamp( $expiry );
4604         }
4605
4606         public function decodeExpiry( $expiry, $format = TS_MW ) {
4607                 if ( $expiry == '' || $expiry == 'infinity' || $expiry == $this->getInfinity() ) {
4608                         return 'infinity';
4609                 }
4610
4611                 return ConvertibleTimestamp::convert( $format, $expiry );
4612         }
4613
4614         public function setBigSelects( $value = true ) {
4615                 // no-op
4616         }
4617
4618         public function isReadOnly() {
4619                 return ( $this->getReadOnlyReason() !== false );
4620         }
4621
4622         /**
4623          * @return string|bool Reason this DB is read-only or false if it is not
4624          */
4625         protected function getReadOnlyReason() {
4626                 $reason = $this->getLBInfo( 'readOnlyReason' );
4627
4628                 return is_string( $reason ) ? $reason : false;
4629         }
4630
4631         public function setTableAliases( array $aliases ) {
4632                 $this->tableAliases = $aliases;
4633         }
4634
4635         public function setIndexAliases( array $aliases ) {
4636                 $this->indexAliases = $aliases;
4637         }
4638
4639         /**
4640          * Get the underlying binding connection handle
4641          *
4642          * Makes sure the connection resource is set (disconnects and ping() failure can unset it).
4643          * This catches broken callers than catch and ignore disconnection exceptions.
4644          * Unlike checking isOpen(), this is safe to call inside of open().
4645          *
4646          * @return mixed
4647          * @throws DBUnexpectedError
4648          * @since 1.26
4649          */
4650         protected function getBindingHandle() {
4651                 if ( !$this->conn ) {
4652                         throw new DBUnexpectedError(
4653                                 $this,
4654                                 'DB connection was already closed or the connection dropped.'
4655                         );
4656                 }
4657
4658                 return $this->conn;
4659         }
4660
4661         /**
4662          * @since 1.19
4663          * @return string
4664          */
4665         public function __toString() {
4666                 return (string)$this->conn;
4667         }
4668
4669         /**
4670          * Make sure that copies do not share the same client binding handle
4671          * @throws DBConnectionError
4672          */
4673         public function __clone() {
4674                 $this->connLogger->warning(
4675                         "Cloning " . static::class . " is not recommended; forking connection:\n" .
4676                         ( new RuntimeException() )->getTraceAsString()
4677                 );
4678
4679                 if ( $this->isOpen() ) {
4680                         // Open a new connection resource without messing with the old one
4681                         $this->opened = false;
4682                         $this->conn = false;
4683                         $this->trxEndCallbacks = []; // don't copy
4684                         $this->handleSessionLoss(); // no trx or locks anymore
4685                         $this->open(
4686                                 $this->server,
4687                                 $this->user,
4688                                 $this->password,
4689                                 $this->getDBname(),
4690                                 $this->dbSchema(),
4691                                 $this->tablePrefix()
4692                         );
4693                         $this->lastPing = microtime( true );
4694                 }
4695         }
4696
4697         /**
4698          * Called by serialize. Throw an exception when DB connection is serialized.
4699          * This causes problems on some database engines because the connection is
4700          * not restored on unserialize.
4701          */
4702         public function __sleep() {
4703                 throw new RuntimeException( 'Database serialization may cause problems, since ' .
4704                         'the connection is not restored on wakeup.' );
4705         }
4706
4707         /**
4708          * Run a few simple sanity checks and close dangling connections
4709          */
4710         public function __destruct() {
4711                 if ( $this->trxLevel && $this->trxDoneWrites ) {
4712                         trigger_error( "Uncommitted DB writes (transaction from {$this->trxFname})." );
4713                 }
4714
4715                 $danglingWriters = $this->pendingWriteAndCallbackCallers();
4716                 if ( $danglingWriters ) {
4717                         $fnames = implode( ', ', $danglingWriters );
4718                         trigger_error( "DB transaction writes or callbacks still pending ($fnames)." );
4719                 }
4720
4721                 if ( $this->conn ) {
4722                         // Avoid connection leaks for sanity. Normally, resources close at script completion.
4723                         // The connection might already be closed in zend/hhvm by now, so suppress warnings.
4724                         Wikimedia\suppressWarnings();
4725                         $this->closeConnection();
4726                         Wikimedia\restoreWarnings();
4727                         $this->conn = false;
4728                         $this->opened = false;
4729                 }
4730         }
4731 }
4732
4733 /**
4734  * @deprecated since 1.28
4735  */
4736 class_alias( Database::class, 'DatabaseBase' );
4737
4738 /**
4739  * @deprecated since 1.29
4740  */
4741 class_alias( Database::class, 'Database' );