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 callable|null */
 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 = is_callable( $params['profiler'] ) ? $params['profiler'] : null;
 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 callback that takes a section name argument and returns
 412          *      a ScopedCallback instance that ends the profile section in its destructor.
 413          *      These will be called in query(), using a simplified version of the SQL that
 414          *      also includes the agent as a SQL comment.
 415          *   - trxProfiler: Optional TransactionProfiler instance.
 416          *   - errorLogger: Optional callback that takes an Exception and logs it.
 417          *   - deprecationLogger: Optional callback that takes a string and logs it.
 418          *   - cliMode: Whether to consider the execution context that of a CLI script.
 419          *   - agent: Optional name used to identify the end-user in query profiling/logging.
 420          *   - srvCache: Optional BagOStuff instance to an APC-style cache.
 421          *   - nonNativeInsertSelectBatchSize: Optional batch size for non-native INSERT SELECT emulation.
 422          * @param int $connect One of the class constants (NEW_CONNECTED, NEW_UNCONNECTED) [optional]
 423          * @return Database|null If the database driver or extension cannot be found
 424          * @throws InvalidArgumentException If the database driver or extension cannot be found
 425          * @since 1.18
 426          */
 427         final public static function factory( $dbType, $p = [], $connect = self::NEW_CONNECTED ) {
 428                 $class = self::getClass( $dbType, $p['driver'] ?? null );
 429
 430                 if ( class_exists( $class ) && is_subclass_of( $class, IDatabase::class ) ) {
 431                         // Resolve some defaults for b/c
 432                         $p['host'] = $p['host'] ?? false;
 433                         $p['user'] = $p['user'] ?? false;
 434                         $p['password'] = $p['password'] ?? false;
 435                         $p['dbname'] = $p['dbname'] ?? false;
 436                         $p['flags'] = $p['flags'] ?? 0;
 437                         $p['variables'] = $p['variables'] ?? [];
 438                         $p['tablePrefix'] = $p['tablePrefix'] ?? '';
 439                         $p['schema'] = $p['schema'] ?? null;
 440                         $p['cliMode'] = $p['cliMode'] ?? ( PHP_SAPI === 'cli' || PHP_SAPI === 'phpdbg' );
 441                         $p['agent'] = $p['agent'] ?? '';
 442                         if ( !isset( $p['connLogger'] ) ) {
 443                                 $p['connLogger'] = new NullLogger();
 444                         }
 445                         if ( !isset( $p['queryLogger'] ) ) {
 446                                 $p['queryLogger'] = new NullLogger();
 447                         }
 448                         $p['profiler'] = $p['profiler'] ?? null;
 449                         if ( !isset( $p['trxProfiler'] ) ) {
 450                                 $p['trxProfiler'] = new TransactionProfiler();
 451                         }
 452                         if ( !isset( $p['errorLogger'] ) ) {
 453                                 $p['errorLogger'] = function ( Exception $e ) {
 454                                         trigger_error( get_class( $e ) . ': ' . $e->getMessage(), E_USER_WARNING );
 455                                 };
 456                         }
 457                         if ( !isset( $p['deprecationLogger'] ) ) {
 458                                 $p['deprecationLogger'] = function ( $msg ) {
 459                                         trigger_error( $msg, E_USER_DEPRECATED );
 460                                 };
 461                         }
 462
 463                         /** @var Database $conn */
 464                         $conn = new $class( $p );
 465                         if ( $connect == self::NEW_CONNECTED ) {
 466                                 $conn->initConnection();
 467                         }
 468                 } else {
 469                         $conn = null;
 470                 }
 471
 472                 return $conn;
 473         }
 474
 475         /**
 476          * @param string $dbType A possible DB type (sqlite, mysql, postgres,...)
 477          * @param string|null $driver Optional name of a specific DB client driver
 478          * @return array Map of (Database::ATTRIBUTE_* constant => value) for all such constants
 479          * @throws InvalidArgumentException
 480          * @since 1.31
 481          */
 482         final public static function attributesFromType( $dbType, $driver = null ) {
 483                 static $defaults = [ self::ATTR_DB_LEVEL_LOCKING => false ];
 484
 485                 $class = self::getClass( $dbType, $driver );
 486
 487                 return call_user_func( [ $class, 'getAttributes' ] ) + $defaults;
 488         }
 489
 490         /**
 491          * @param string $dbType A possible DB type (sqlite, mysql, postgres,...)
 492          * @param string|null $driver Optional name of a specific DB client driver
 493          * @return string Database subclass name to use
 494          * @throws InvalidArgumentException
 495          */
 496         private static function getClass( $dbType, $driver = null ) {
 497                 // For database types with built-in support, the below maps type to IDatabase
 498                 // implementations. For types with multipe driver implementations (PHP extensions),
 499                 // an array can be used, keyed by extension name. In case of an array, the
 500                 // optional 'driver' parameter can be used to force a specific driver. Otherwise,
 501                 // we auto-detect the first available driver. For types without built-in support,
 502                 // an class named "Database<Type>" us used, eg. DatabaseFoo for type 'foo'.
 503                 static $builtinTypes = [
 504                         'mssql' => DatabaseMssql::class,
 505                         'mysql' => [ 'mysqli' => DatabaseMysqli::class ],
 506                         'sqlite' => DatabaseSqlite::class,
 507                         'postgres' => DatabasePostgres::class,
 508                 ];
 509
 510                 $dbType = strtolower( $dbType );
 511                 $class = false;
 512
 513                 if ( isset( $builtinTypes[$dbType] ) ) {
 514                         $possibleDrivers = $builtinTypes[$dbType];
 515                         if ( is_string( $possibleDrivers ) ) {
 516                                 $class = $possibleDrivers;
 517                         } else {
 518                                 if ( (string)$driver !== '' ) {
 519                                         if ( !isset( $possibleDrivers[$driver] ) ) {
 520                                                 throw new InvalidArgumentException( __METHOD__ .
 521                                                         " type '$dbType' does not support driver '{$driver}'" );
 522                                         } else {
 523                                                 $class = $possibleDrivers[$driver];
 524                                         }
 525                                 } else {
 526                                         foreach ( $possibleDrivers as $posDriver => $possibleClass ) {
 527                                                 if ( extension_loaded( $posDriver ) ) {
 528                                                         $class = $possibleClass;
 529                                                         break;
 530                                                 }
 531                                         }
 532                                 }
 533                         }
 534                 } else {
 535                         $class = 'Database' . ucfirst( $dbType );
 536                 }
 537
 538                 if ( $class === false ) {
 539                         throw new InvalidArgumentException( __METHOD__ .
 540                                 " no viable database extension found for type '$dbType'" );
 541                 }
 542
 543                 return $class;
 544         }
 545
 546         /**
 547          * @return array Map of (Database::ATTRIBUTE_* constant => value
 548          * @since 1.31
 549          */
 550         protected static function getAttributes() {
 551                 return [];
 552         }
 553
 554         /**
 555          * Set the PSR-3 logger interface to use for query logging. (The logger
 556          * interfaces for connection logging and error logging can be set with the
 557          * constructor.)
 558          *
 559          * @param LoggerInterface $logger
 560          */
 561         public function setLogger( LoggerInterface $logger ) {
 562                 $this->queryLogger = $logger;
 563         }
 564
 565         public function getServerInfo() {
 566                 return $this->getServerVersion();
 567         }
 568
 569         public function bufferResults( $buffer = null ) {
 570                 $res = !$this->getFlag( self::DBO_NOBUFFER );
 571                 if ( $buffer !== null ) {
 572                         $buffer
 573                                 ? $this->clearFlag( self::DBO_NOBUFFER )
 574                                 : $this->setFlag( self::DBO_NOBUFFER );
 575                 }
 576
 577                 return $res;
 578         }
 579
 580         public function trxLevel() {
 581                 return $this->trxLevel;
 582         }
 583
 584         public function trxTimestamp() {
 585                 return $this->trxLevel ? $this->trxTimestamp : null;
 586         }
 587
 588         /**
 589          * @return int One of the STATUS_TRX_* class constants
 590          * @since 1.31
 591          */
 592         public function trxStatus() {
 593                 return $this->trxStatus;
 594         }
 595
 596         public function tablePrefix( $prefix = null ) {
 597                 $old = $this->currentDomain->getTablePrefix();
 598                 if ( $prefix !== null ) {
 599                         $this->currentDomain = new DatabaseDomain(
 600                                 $this->currentDomain->getDatabase(),
 601                                 $this->currentDomain->getSchema(),
 602                                 $prefix
 603                         );
 604                 }
 605
 606                 return $old;
 607         }
 608
 609         public function dbSchema( $schema = null ) {
 610                 $old = $this->currentDomain->getSchema();
 611                 if ( $schema !== null ) {
 612                         $this->currentDomain = new DatabaseDomain(
 613                                 $this->currentDomain->getDatabase(),
 614                                 // DatabaseDomain uses null for unspecified schemas
 615                                 strlen( $schema ) ? $schema : null,
 616                                 $this->currentDomain->getTablePrefix()
 617                         );
 618                 }
 619
 620                 return (string)$old;
 621         }
 622
 623         /**
 624          * @return string Schema to use to qualify relations in queries
 625          */
 626         protected function relationSchemaQualifier() {
 627                 return $this->dbSchema();
 628         }
 629
 630         public function getLBInfo( $name = null ) {
 631                 if ( is_null( $name ) ) {
 632                         return $this->lbInfo;
 633                 } else {
 634                         if ( array_key_exists( $name, $this->lbInfo ) ) {
 635                                 return $this->lbInfo[$name];
 636                         } else {
 637                                 return null;
 638                         }
 639                 }
 640         }
 641
 642         public function setLBInfo( $name, $value = null ) {
 643                 if ( is_null( $value ) ) {
 644                         $this->lbInfo = $name;
 645                 } else {
 646                         $this->lbInfo[$name] = $value;
 647                 }
 648         }
 649
 650         public function setLazyMasterHandle( IDatabase $conn ) {
 651                 $this->lazyMasterHandle = $conn;
 652         }
 653
 654         /**
 655          * @return IDatabase|null
 656          * @see setLazyMasterHandle()
 657          * @since 1.27
 658          */
 659         protected function getLazyMasterHandle() {
 660                 return $this->lazyMasterHandle;
 661         }
 662
 663         public function implicitGroupby() {
 664                 return true;
 665         }
 666
 667         public function implicitOrderby() {
 668                 return true;
 669         }
 670
 671         public function lastQuery() {
 672                 return $this->lastQuery;
 673         }
 674
 675         public function doneWrites() {
 676                 return (bool)$this->lastWriteTime;
 677         }
 678
 679         public function lastDoneWrites() {
 680                 return $this->lastWriteTime ?: false;
 681         }
 682
 683         public function writesPending() {
 684                 return $this->trxLevel && $this->trxDoneWrites;
 685         }
 686
 687         public function writesOrCallbacksPending() {
 688                 return $this->trxLevel && (
 689                         $this->trxDoneWrites ||
 690                         $this->trxIdleCallbacks ||
 691                         $this->trxPreCommitCallbacks ||
 692                         $this->trxEndCallbacks
 693                 );
 694         }
 695
 696         public function preCommitCallbacksPending() {
 697                 return $this->trxLevel && $this->trxPreCommitCallbacks;
 698         }
 699
 700         /**
 701          * @return string|null
 702          */
 703         final protected function getTransactionRoundId() {
 704                 // If transaction round participation is enabled, see if one is active
 705                 if ( $this->getFlag( self::DBO_TRX ) ) {
 706                         $id = $this->getLBInfo( 'trxRoundId' );
 707
 708                         return is_string( $id ) ? $id : null;
 709                 }
 710
 711                 return null;
 712         }
 713
 714         public function pendingWriteQueryDuration( $type = self::ESTIMATE_TOTAL ) {
 715                 if ( !$this->trxLevel ) {
 716                         return false;
 717                 } elseif ( !$this->trxDoneWrites ) {
 718                         return 0.0;
 719                 }
 720
 721                 switch ( $type ) {
 722                         case self::ESTIMATE_DB_APPLY:
 723                                 return $this->pingAndCalculateLastTrxApplyTime();
 724                         default: // everything
 725                                 return $this->trxWriteDuration;
 726                 }
 727         }
 728
 729         /**
 730          * @return float Time to apply writes to replicas based on trxWrite* fields
 731          */
 732         private function pingAndCalculateLastTrxApplyTime() {
 733                 $this->ping( $rtt );
 734
 735                 $rttAdjTotal = $this->trxWriteAdjQueryCount * $rtt;
 736                 $applyTime = max( $this->trxWriteAdjDuration - $rttAdjTotal, 0 );
 737                 // For omitted queries, make them count as something at least
 738                 $omitted = $this->trxWriteQueryCount - $this->trxWriteAdjQueryCount;
 739                 $applyTime += self::TINY_WRITE_SEC * $omitted;
 740
 741                 return $applyTime;
 742         }
 743
 744         public function pendingWriteCallers() {
 745                 return $this->trxLevel ? $this->trxWriteCallers : [];
 746         }
 747
 748         public function pendingWriteRowsAffected() {
 749                 return $this->trxWriteAffectedRows;
 750         }
 751
 752         /**
 753          * List the methods that have write queries or callbacks for the current transaction
 754          *
 755          * This method should not be used outside of Database/LoadBalancer
 756          *
 757          * @return string[]
 758          * @since 1.32
 759          */
 760         public function pendingWriteAndCallbackCallers() {
 761                 $fnames = $this->pendingWriteCallers();
 762                 foreach ( [
 763                         $this->trxIdleCallbacks,
 764                         $this->trxPreCommitCallbacks,
 765                         $this->trxEndCallbacks
 766                 ] as $callbacks ) {
 767                         foreach ( $callbacks as $callback ) {
 768                                 $fnames[] = $callback[1];
 769                         }
 770                 }
 771
 772                 return $fnames;
 773         }
 774
 775         /**
 776          * @return string
 777          */
 778         private function flatAtomicSectionList() {
 779                 return array_reduce( $this->trxAtomicLevels, function ( $accum, $v ) {
 780                         return $accum === null ? $v[0] : "$accum, " . $v[0];
 781                 } );
 782         }
 783
 784         public function isOpen() {
 785                 return $this->opened;
 786         }
 787
 788         public function setFlag( $flag, $remember = self::REMEMBER_NOTHING ) {
 789                 if ( ( $flag & self::DBO_IGNORE ) ) {
 790                         throw new UnexpectedValueException( "Modifying DBO_IGNORE is not allowed." );
 791                 }
 792
 793                 if ( $remember === self::REMEMBER_PRIOR ) {
 794                         array_push( $this->priorFlags, $this->flags );
 795                 }
 796                 $this->flags |= $flag;
 797         }
 798
 799         public function clearFlag( $flag, $remember = self::REMEMBER_NOTHING ) {
 800                 if ( ( $flag & self::DBO_IGNORE ) ) {
 801                         throw new UnexpectedValueException( "Modifying DBO_IGNORE is not allowed." );
 802                 }
 803
 804                 if ( $remember === self::REMEMBER_PRIOR ) {
 805                         array_push( $this->priorFlags, $this->flags );
 806                 }
 807                 $this->flags &= ~$flag;
 808         }
 809
 810         public function restoreFlags( $state = self::RESTORE_PRIOR ) {
 811                 if ( !$this->priorFlags ) {
 812                         return;
 813                 }
 814
 815                 if ( $state === self::RESTORE_INITIAL ) {
 816                         $this->flags = reset( $this->priorFlags );
 817                         $this->priorFlags = [];
 818                 } else {
 819                         $this->flags = array_pop( $this->priorFlags );
 820                 }
 821         }
 822
 823         public function getFlag( $flag ) {
 824                 return (bool)( $this->flags & $flag );
 825         }
 826
 827         /**
 828          * @param string $name Class field name
 829          * @return mixed
 830          * @deprecated Since 1.28
 831          */
 832         public function getProperty( $name ) {
 833                 return $this->$name;
 834         }
 835
 836         public function getDomainID() {
 837                 return $this->currentDomain->getId();
 838         }
 839
 840         final public function getWikiID() {
 841                 return $this->getDomainID();
 842         }
 843
 844         /**
 845          * Get information about an index into an object
 846          * @param string $table Table name
 847          * @param string $index Index name
 848          * @param string $fname Calling function name
 849          * @return mixed Database-specific index description class or false if the index does not exist
 850          */
 851         abstract function indexInfo( $table, $index, $fname = __METHOD__ );
 852
 853         /**
 854          * Wrapper for addslashes()
 855          *
 856          * @param string $s String to be slashed.
 857          * @return string Slashed string.
 858          */
 859         abstract function strencode( $s );
 860
 861         /**
 862          * Set a custom error handler for logging errors during database connection
 863          */
 864         protected function installErrorHandler() {
 865                 $this->phpError = false;
 866                 $this->htmlErrors = ini_set( 'html_errors', '0' );
 867                 set_error_handler( [ $this, 'connectionErrorLogger' ] );
 868         }
 869
 870         /**
 871          * Restore the previous error handler and return the last PHP error for this DB
 872          *
 873          * @return bool|string
 874          */
 875         protected function restoreErrorHandler() {
 876                 restore_error_handler();
 877                 if ( $this->htmlErrors !== false ) {
 878                         ini_set( 'html_errors', $this->htmlErrors );
 879                 }
 880
 881                 return $this->getLastPHPError();
 882         }
 883
 884         /**
 885          * @return string|bool Last PHP error for this DB (typically connection errors)
 886          */
 887         protected function getLastPHPError() {
 888                 if ( $this->phpError ) {
 889                         $error = preg_replace( '!\[<a.*</a>\]!', '', $this->phpError );
 890                         $error = preg_replace( '!^.*?:\s?(.*)$!', '$1', $error );
 891
 892                         return $error;
 893                 }
 894
 895                 return false;
 896         }
 897
 898         /**
 899          * Error handler for logging errors during database connection
 900          * This method should not be used outside of Database classes
 901          *
 902          * @param int $errno
 903          * @param string $errstr
 904          */
 905         public function connectionErrorLogger( $errno, $errstr ) {
 906                 $this->phpError = $errstr;
 907         }
 908
 909         /**
 910          * Create a log context to pass to PSR-3 logger functions.
 911          *
 912          * @param array $extras Additional data to add to context
 913          * @return array
 914          */
 915         protected function getLogContext( array $extras = [] ) {
 916                 return array_merge(
 917                         [
 918                                 'db_server' => $this->server,
 919                                 'db_name' => $this->getDBname(),
 920                                 'db_user' => $this->user,
 921                         ],
 922                         $extras
 923                 );
 924         }
 925
 926         final public function close() {
 927                 $exception = null; // error to throw after disconnecting
 928
 929                 if ( $this->conn ) {
 930                         // Roll back any dangling transaction first
 931                         if ( $this->trxLevel ) {
 932                                 if ( $this->trxAtomicLevels ) {
 933                                         // Cannot let incomplete atomic sections be committed
 934                                         $levels = $this->flatAtomicSectionList();
 935                                         $exception = new DBUnexpectedError(
 936                                                 $this,
 937                                                 __METHOD__ . ": atomic sections $levels are still open."
 938                                         );
 939                                 } elseif ( $this->trxAutomatic ) {
 940                                         // Only the connection manager can commit non-empty DBO_TRX transactions
 941                                         // (empty ones we can silently roll back)
 942                                         if ( $this->writesOrCallbacksPending() ) {
 943                                                 $exception = new DBUnexpectedError(
 944                                                         $this,
 945                                                         __METHOD__ .
 946                                                         ": mass commit/rollback of peer transaction required (DBO_TRX set)."
 947                                                 );
 948                                         }
 949                                 } else {
 950                                         // Manual transactions should have been committed or rolled
 951                                         // back, even if empty.
 952                                         $exception = new DBUnexpectedError(
 953                                                 $this,
 954                                                 __METHOD__ . ": transaction is still open (from {$this->trxFname})."
 955                                         );
 956                                 }
 957
 958                                 if ( $this->trxEndCallbacksSuppressed ) {
 959                                         $exception = $exception ?: new DBUnexpectedError(
 960                                                 $this,
 961                                                 __METHOD__ . ': callbacks are suppressed; cannot properly commit.'
 962                                         );
 963                                 }
 964
 965                                 // Rollback the changes and run any callbacks as needed
 966                                 $this->rollback( __METHOD__, self::FLUSHING_INTERNAL );
 967                         }
 968
 969                         // Close the actual connection in the binding handle
 970                         $closed = $this->closeConnection();
 971                         $this->conn = false;
 972                 } else {
 973                         $closed = true; // already closed; nothing to do
 974                 }
 975
 976                 $this->opened = false;
 977
 978                 // Throw any unexpected errors after having disconnected
 979                 if ( $exception instanceof Exception ) {
 980                         throw $exception;
 981                 }
 982
 983                 // Sanity check that no callbacks are dangling
 984                 $fnames = $this->pendingWriteAndCallbackCallers();
 985                 if ( $fnames ) {
 986                         throw new RuntimeException(
 987                                 "Transaction callbacks are still pending:\n" . implode( ', ', $fnames )
 988                         );
 989                 }
 990
 991                 return $closed;
 992         }
 993
 994         /**
 995          * Make sure there is an open connection handle (alive or not) as a sanity check
 996          *
 997          * This guards against fatal errors to the binding handle not being defined
 998          * in cases where open() was never called or close() was already called
 999          *
1000          * @throws DBUnexpectedError
1001          */
1002         protected function assertHasConnectionHandle() {
1003                 if ( !$this->isOpen() ) {
1004                         throw new DBUnexpectedError( $this, "DB connection was already closed." );
1005                 }
1006         }
1007
1008         /**
1009          * Make sure that this server is not marked as a replica nor read-only as a sanity check
1010          *
1011          * @throws DBUnexpectedError
1012          */
1013         protected function assertIsWritableMaster() {
1014                 if ( $this->getLBInfo( 'replica' ) === true ) {
1015                         throw new DBUnexpectedError(
1016                                 $this,
1017                                 'Write operations are not allowed on replica database connections.'
1018                         );
1019                 }
1020                 $reason = $this->getReadOnlyReason();
1021                 if ( $reason !== false ) {
1022                         throw new DBReadOnlyError( $this, "Database is read-only: $reason" );
1023                 }
1024         }
1025
1026         /**
1027          * Closes underlying database connection
1028          * @since 1.20
1029          * @return bool Whether connection was closed successfully
1030          */
1031         abstract protected function closeConnection();
1032
1033         /**
1034          * @deprecated since 1.32
1035          * @param string $error Fallback message, if none is given by DB
1036          * @throws DBConnectionError
1037          */
1038         public function reportConnectionError( $error = 'Unknown error' ) {
1039                 call_user_func( $this->deprecationLogger, 'Use of ' . __METHOD__ . ' is deprecated.' );
1040                 throw new DBConnectionError( $this, $this->lastError() ?: $error );
1041         }
1042
1043         /**
1044          * Run a query and return a DBMS-dependent wrapper or boolean
1045          *
1046          * For SELECT queries, this returns either:
1047          *   - a) A driver-specific value/resource, only on success. This can be iterated
1048          *        over by calling fetchObject()/fetchRow() until there are no more rows.
1049          *        Alternatively, the result can be passed to resultObject() to obtain a
1050          *        ResultWrapper instance which can then be iterated over via "foreach".
1051          *   - b) False, on any query failure
1052          *
1053          * For non-SELECT queries, this returns either:
1054          *   - a) A driver-specific value/resource, only on success
1055          *   - b) True, only on success (e.g. no meaningful result other than "OK")
1056          *   - c) False, on any query failure
1057          *
1058          * @param string $sql SQL query
1059          * @return mixed|bool An object, resource, or true on success; false on failure
1060          */
1061         abstract protected function doQuery( $sql );
1062
1063         /**
1064          * Determine whether a query writes to the DB. When in doubt, this returns true.
1065          *
1066          * Main use cases:
1067          *
1068          * - Subsequent web requests should not need to wait for replication from
1069          *   the master position seen by this web request, unless this request made
1070          *   changes to the master. This is handled by ChronologyProtector by checking
1071          *   doneWrites() at the end of the request. doneWrites() returns true if any
1072          *   query set lastWriteTime; which query() does based on isWriteQuery().
1073          *
1074          * - Reject write queries to replica DBs, in query().
1075          *
1076          * @param string $sql
1077          * @return bool
1078          */
1079         protected function isWriteQuery( $sql ) {
1080                 // BEGIN and COMMIT queries are considered read queries here.
1081                 // Database backends and drivers (MySQL, MariaDB, php-mysqli) generally
1082                 // treat these as write queries, in that their results have "affected rows"
1083                 // as meta data as from writes, instead of "num rows" as from reads.
1084                 // But, we treat them as read queries because when reading data (from
1085                 // either replica or master) we use transactions to enable repeatable-read
1086                 // snapshots, which ensures we get consistent results from the same snapshot
1087                 // for all queries within a request. Use cases:
1088                 // - Treating these as writes would trigger ChronologyProtector (see method doc).
1089                 // - We use this method to reject writes to replicas, but we need to allow
1090                 //   use of transactions on replicas for read snapshots. This fine given
1091                 //   that transactions by themselves don't make changes, only actual writes
1092                 //   within the transaction matter, which we still detect.
1093                 return !preg_match(
1094                         '/^(?:SELECT|BEGIN|ROLLBACK|COMMIT|SAVEPOINT|RELEASE|SET|SHOW|EXPLAIN|\(SELECT)\b/i',
1095                         $sql
1096                 );
1097         }
1098
1099         /**
1100          * @param string $sql
1101          * @return string|null
1102          */
1103         protected function getQueryVerb( $sql ) {
1104                 return preg_match( '/^\s*([a-z]+)/i', $sql, $m ) ? strtoupper( $m[1] ) : null;
1105         }
1106
1107         /**
1108          * Determine whether a SQL statement is sensitive to isolation level.
1109          *
1110          * A SQL statement is considered transactable if its result could vary
1111          * depending on the transaction isolation level. Operational commands
1112          * such as 'SET' and 'SHOW' are not considered to be transactable.
1113          *
1114          * Main purpose: Used by query() to decide whether to begin a transaction
1115          * before the current query (in DBO_TRX mode, on by default).
1116          *
1117          * @param string $sql
1118          * @return bool
1119          */
1120         protected function isTransactableQuery( $sql ) {
1121                 return !in_array(
1122                         $this->getQueryVerb( $sql ),
1123                         [ 'BEGIN', 'ROLLBACK', 'COMMIT', 'SET', 'SHOW', 'CREATE', 'ALTER' ],
1124                         true
1125                 );
1126         }
1127
1128         /**
1129          * @param string $sql A SQL query
1130          * @return bool Whether $sql is SQL for TEMPORARY table operation
1131          */
1132         protected function registerTempTableOperation( $sql ) {
1133                 if ( preg_match(
1134                         '/^CREATE\s+TEMPORARY\s+TABLE\s+(?:IF\s+NOT\s+EXISTS\s+)?[`"\']?(\w+)[`"\']?/i',
1135                         $sql,
1136                         $matches
1137                 ) ) {
1138                         $this->sessionTempTables[$matches[1]] = 1;
1139
1140                         return true;
1141                 } elseif ( preg_match(
1142                         '/^DROP\s+(?:TEMPORARY\s+)?TABLE\s+(?:IF\s+EXISTS\s+)?[`"\']?(\w+)[`"\']?/i',
1143                         $sql,
1144                         $matches
1145                 ) ) {
1146                         $isTemp = isset( $this->sessionTempTables[$matches[1]] );
1147                         unset( $this->sessionTempTables[$matches[1]] );
1148
1149                         return $isTemp;
1150                 } elseif ( preg_match(
1151                         '/^TRUNCATE\s+(?:TEMPORARY\s+)?TABLE\s+(?:IF\s+EXISTS\s+)?[`"\']?(\w+)[`"\']?/i',
1152                         $sql,
1153                         $matches
1154                 ) ) {
1155                         return isset( $this->sessionTempTables[$matches[1]] );
1156                 } elseif ( preg_match(
1157                         '/^(?:INSERT\s+(?:\w+\s+)?INTO|UPDATE|DELETE\s+FROM)\s+[`"\']?(\w+)[`"\']?/i',
1158                         $sql,
1159                         $matches
1160                 ) ) {
1161                         return isset( $this->sessionTempTables[$matches[1]] );
1162                 }
1163
1164                 return false;
1165         }
1166
1167         public function query( $sql, $fname = __METHOD__, $tempIgnore = false ) {
1168                 $this->assertTransactionStatus( $sql, $fname );
1169                 $this->assertHasConnectionHandle();
1170
1171                 $priorTransaction = $this->trxLevel;
1172                 $priorWritesPending = $this->writesOrCallbacksPending();
1173                 $this->lastQuery = $sql;
1174
1175                 if ( $this->isWriteQuery( $sql ) ) {
1176                         # In theory, non-persistent writes are allowed in read-only mode, but due to things
1177                         # like https://bugs.mysql.com/bug.php?id=33669 that might not work anyway...
1178                         $this->assertIsWritableMaster();
1179                         # Avoid treating temporary table operations as meaningful "writes"
1180                         $isEffectiveWrite = !$this->registerTempTableOperation( $sql );
1181                 } else {
1182                         $isEffectiveWrite = false;
1183                 }
1184
1185                 # Add trace comment to the begin of the sql string, right after the operator.
1186                 # Or, for one-word queries (like "BEGIN" or COMMIT") add it to the end (T44598)
1187                 $commentedSql = preg_replace( '/\s|$/', " /* $fname {$this->agent} */ ", $sql, 1 );
1188
1189                 # Send the query to the server and fetch any corresponding errors
1190                 $ret = $this->attemptQuery( $sql, $commentedSql, $isEffectiveWrite, $fname );
1191                 $lastError = $this->lastError();
1192                 $lastErrno = $this->lastErrno();
1193
1194                 $recoverableSR = false; // recoverable statement rollback?
1195                 $recoverableCL = false; // recoverable connection loss?
1196
1197                 if ( $ret === false && $this->wasConnectionLoss() ) {
1198                         # Check if no meaningful session state was lost
1199                         $recoverableCL = $this->canRecoverFromDisconnect( $sql, $priorWritesPending );
1200                         # Update session state tracking and try to restore the connection
1201                         $reconnected = $this->replaceLostConnection( __METHOD__ );
1202                         # Silently resend the query to the server if it is safe and possible
1203                         if ( $recoverableCL && $reconnected ) {
1204                                 $ret = $this->attemptQuery( $sql, $commentedSql, $isEffectiveWrite, $fname );
1205                                 $lastError = $this->lastError();
1206                                 $lastErrno = $this->lastErrno();
1207
1208                                 if ( $ret === false && $this->wasConnectionLoss() ) {
1209                                         # Query probably causes disconnects; reconnect and do not re-run it
1210                                         $this->replaceLostConnection( __METHOD__ );
1211                                 } else {
1212                                         $recoverableCL = false; // connection does not need recovering
1213                                         $recoverableSR = $this->wasKnownStatementRollbackError();
1214                                 }
1215                         }
1216                 } else {
1217                         $recoverableSR = $this->wasKnownStatementRollbackError();
1218                 }
1219
1220                 if ( $ret === false ) {
1221                         if ( $priorTransaction ) {
1222                                 if ( $recoverableSR ) {
1223                                         # We're ignoring an error that caused just the current query to be aborted.
1224                                         # But log the cause so we can log a deprecation notice if a caller actually
1225                                         # does ignore it.
1226                                         $this->trxStatusIgnoredCause = [ $lastError, $lastErrno, $fname ];
1227                                 } elseif ( !$recoverableCL ) {
1228                                         # Either the query was aborted or all queries after BEGIN where aborted.
1229                                         # In the first case, the only options going forward are (a) ROLLBACK, or
1230                                         # (b) ROLLBACK TO SAVEPOINT (if one was set). If the later case, the only
1231                                         # option is ROLLBACK, since the snapshots would have been released.
1232                                         $this->trxStatus = self::STATUS_TRX_ERROR;
1233                                         $this->trxStatusCause =
1234                                                 $this->getQueryExceptionAndLog( $lastError, $lastErrno, $sql, $fname );
1235                                         $tempIgnore = false; // cannot recover
1236                                         $this->trxStatusIgnoredCause = null;
1237                                 }
1238                         }
1239
1240                         $this->reportQueryError( $lastError, $lastErrno, $sql, $fname, $tempIgnore );
1241                 }
1242
1243                 return $this->resultObject( $ret );
1244         }
1245
1246         /**
1247          * Wrapper for query() that also handles profiling, logging, and affected row count updates
1248          *
1249          * @param string $sql Original SQL query
1250          * @param string $commentedSql SQL query with debugging/trace comment
1251          * @param bool $isEffectiveWrite Whether the query is a (non-temporary table) write
1252          * @param string $fname Name of the calling function
1253          * @return bool|ResultWrapper True for a successful write query, ResultWrapper
1254          *     object for a successful read query, or false on failure
1255          */
1256         private function attemptQuery( $sql, $commentedSql, $isEffectiveWrite, $fname ) {
1257                 $this->beginIfImplied( $sql, $fname );
1258
1259                 # Keep track of whether the transaction has write queries pending
1260                 if ( $isEffectiveWrite ) {
1261                         $this->lastWriteTime = microtime( true );
1262                         if ( $this->trxLevel && !$this->trxDoneWrites ) {
1263                                 $this->trxDoneWrites = true;
1264                                 $this->trxProfiler->transactionWritingIn(
1265                                         $this->server, $this->getDomainID(), $this->trxShortId );
1266                         }
1267                 }
1268
1269                 if ( $this->getFlag( self::DBO_DEBUG ) ) {
1270                         $this->queryLogger->debug( "{$this->getDomainID()} {$commentedSql}" );
1271                 }
1272
1273                 $isMaster = !is_null( $this->getLBInfo( 'master' ) );
1274                 # generalizeSQL() will probably cut down the query to reasonable
1275                 # logging size most of the time. The substr is really just a sanity check.
1276                 if ( $isMaster ) {
1277                         $queryProf = 'query-m: ' . substr( self::generalizeSQL( $sql ), 0, 255 );
1278                 } else {
1279                         $queryProf = 'query: ' . substr( self::generalizeSQL( $sql ), 0, 255 );
1280                 }
1281
1282                 # Include query transaction state
1283                 $queryProf .= $this->trxShortId ? " [TRX#{$this->trxShortId}]" : "";
1284
1285                 $startTime = microtime( true );
1286                 $ps = $this->profiler ? ( $this->profiler )( $queryProf ) : null;
1287                 $this->affectedRowCount = null;
1288                 $ret = $this->doQuery( $commentedSql );
1289                 $this->affectedRowCount = $this->affectedRows();
1290                 unset( $ps ); // profile out (if set)
1291                 $queryRuntime = max( microtime( true ) - $startTime, 0.0 );
1292
1293                 if ( $ret !== false ) {
1294                         $this->lastPing = $startTime;
1295                         if ( $isEffectiveWrite && $this->trxLevel ) {
1296                                 $this->updateTrxWriteQueryTime( $sql, $queryRuntime, $this->affectedRows() );
1297                                 $this->trxWriteCallers[] = $fname;
1298                         }
1299                 }
1300
1301                 if ( $sql === self::PING_QUERY ) {
1302                         $this->rttEstimate = $queryRuntime;
1303                 }
1304
1305                 $this->trxProfiler->recordQueryCompletion(
1306                         $queryProf,
1307                         $startTime,
1308                         $isEffectiveWrite,
1309                         $isEffectiveWrite ? $this->affectedRows() : $this->numRows( $ret )
1310                 );
1311                 $this->queryLogger->debug( $sql, [
1312                         'method' => $fname,
1313                         'master' => $isMaster,
1314                         'runtime' => $queryRuntime,
1315                 ] );
1316
1317                 return $ret;
1318         }
1319
1320         /**
1321          * Start an implicit transaction if DBO_TRX is enabled and no transaction is active
1322          *
1323          * @param string $sql
1324          * @param string $fname
1325          */
1326         private function beginIfImplied( $sql, $fname ) {
1327                 if (
1328                         !$this->trxLevel &&
1329                         $this->getFlag( self::DBO_TRX ) &&
1330                         $this->isTransactableQuery( $sql )
1331                 ) {
1332                         $this->begin( __METHOD__ . " ($fname)", self::TRANSACTION_INTERNAL );
1333                         $this->trxAutomatic = true;
1334                 }
1335         }
1336
1337         /**
1338          * Update the estimated run-time of a query, not counting large row lock times
1339          *
1340          * LoadBalancer can be set to rollback transactions that will create huge replication
1341          * lag. It bases this estimate off of pendingWriteQueryDuration(). Certain simple
1342          * queries, like inserting a row can take a long time due to row locking. This method
1343          * uses some simple heuristics to discount those cases.
1344          *
1345          * @param string $sql A SQL write query
1346          * @param float $runtime Total runtime, including RTT
1347          * @param int $affected Affected row count
1348          */
1349         private function updateTrxWriteQueryTime( $sql, $runtime, $affected ) {
1350                 // Whether this is indicative of replica DB runtime (except for RBR or ws_repl)
1351                 $indicativeOfReplicaRuntime = true;
1352                 if ( $runtime > self::SLOW_WRITE_SEC ) {
1353                         $verb = $this->getQueryVerb( $sql );
1354                         // insert(), upsert(), replace() are fast unless bulky in size or blocked on locks
1355                         if ( $verb === 'INSERT' ) {
1356                                 $indicativeOfReplicaRuntime = $this->affectedRows() > self::SMALL_WRITE_ROWS;
1357                         } elseif ( $verb === 'REPLACE' ) {
1358                                 $indicativeOfReplicaRuntime = $this->affectedRows() > self::SMALL_WRITE_ROWS / 2;
1359                         }
1360                 }
1361
1362                 $this->trxWriteDuration += $runtime;
1363                 $this->trxWriteQueryCount += 1;
1364                 $this->trxWriteAffectedRows += $affected;
1365                 if ( $indicativeOfReplicaRuntime ) {
1366                         $this->trxWriteAdjDuration += $runtime;
1367                         $this->trxWriteAdjQueryCount += 1;
1368                 }
1369         }
1370
1371         /**
1372          * Error out if the DB is not in a valid state for a query via query()
1373          *
1374          * @param string $sql
1375          * @param string $fname
1376          * @throws DBTransactionStateError
1377          */
1378         private function assertTransactionStatus( $sql, $fname ) {
1379                 $verb = $this->getQueryVerb( $sql );
1380                 if ( $verb === 'USE' ) {
1381                         throw new DBUnexpectedError( $this, "Got USE query; use selectDomain() instead." );
1382                 }
1383
1384                 if ( $verb === 'ROLLBACK' ) { // transaction/savepoint
1385                         return;
1386                 }
1387
1388                 if ( $this->trxStatus < self::STATUS_TRX_OK ) {
1389                         throw new DBTransactionStateError(
1390                                 $this,
1391                                 "Cannot execute query from $fname while transaction status is ERROR.",
1392                                 [],
1393                                 $this->trxStatusCause
1394                         );
1395                 } elseif ( $this->trxStatus === self::STATUS_TRX_OK && $this->trxStatusIgnoredCause ) {
1396                         list( $iLastError, $iLastErrno, $iFname ) = $this->trxStatusIgnoredCause;
1397                         call_user_func( $this->deprecationLogger,
1398                                 "Caller from $fname ignored an error originally raised from $iFname: " .
1399                                 "[$iLastErrno] $iLastError"
1400                         );
1401                         $this->trxStatusIgnoredCause = null;
1402                 }
1403         }
1404
1405         public function assertNoOpenTransactions() {
1406                 if ( $this->explicitTrxActive() ) {
1407                         throw new DBTransactionError(
1408                                 $this,
1409                                 "Explicit transaction still active. A caller may have caught an error. "
1410                                 . "Open transactions: " . $this->flatAtomicSectionList()
1411                         );
1412                 }
1413         }
1414
1415         /**
1416          * Determine whether it is safe to retry queries after a database connection is lost
1417          *
1418          * @param string $sql SQL query
1419          * @param bool $priorWritesPending Whether there is a transaction open with
1420          *     possible write queries or transaction pre-commit/idle callbacks
1421          *     waiting on it to finish.
1422          * @return bool True if it is safe to retry the query, false otherwise
1423          */
1424         private function canRecoverFromDisconnect( $sql, $priorWritesPending ) {
1425                 # Transaction dropped; this can mean lost writes, or REPEATABLE-READ snapshots.
1426                 # Dropped connections also mean that named locks are automatically released.
1427                 # Only allow error suppression in autocommit mode or when the lost transaction
1428                 # didn't matter anyway (aside from DBO_TRX snapshot loss).
1429                 if ( $this->namedLocksHeld ) {
1430                         return false; // possible critical section violation
1431                 } elseif ( $this->sessionTempTables ) {
1432                         return false; // tables might be queried latter
1433                 } elseif ( $sql === 'COMMIT' ) {
1434                         return !$priorWritesPending; // nothing written anyway? (T127428)
1435                 } elseif ( $sql === 'ROLLBACK' ) {
1436                         return true; // transaction lost...which is also what was requested :)
1437                 } elseif ( $this->explicitTrxActive() ) {
1438                         return false; // don't drop atomocity and explicit snapshots
1439                 } elseif ( $priorWritesPending ) {
1440                         return false; // prior writes lost from implicit transaction
1441                 }
1442
1443                 return true;
1444         }
1445
1446         /**
1447          * Clean things up after session (and thus transaction) loss
1448          */
1449         private function handleSessionLoss() {
1450                 // Clean up tracking of session-level things...
1451                 // https://dev.mysql.com/doc/refman/5.7/en/implicit-commit.html
1452                 // https://www.postgresql.org/docs/9.2/static/sql-createtable.html (ignoring ON COMMIT)
1453                 $this->sessionTempTables = [];
1454                 // https://dev.mysql.com/doc/refman/5.7/en/miscellaneous-functions.html#function_get-lock
1455                 // https://www.postgresql.org/docs/9.4/static/functions-admin.html#FUNCTIONS-ADVISORY-LOCKS
1456                 $this->namedLocksHeld = [];
1457                 // Session loss implies transaction loss
1458                 $this->handleTransactionLoss();
1459         }
1460
1461         /**
1462          * Clean things up after transaction loss
1463          */
1464         private function handleTransactionLoss() {
1465                 if ( $this->trxDoneWrites ) {
1466                         $this->trxProfiler->transactionWritingOut(
1467                                 $this->server,
1468                                 $this->getDomainID(),
1469                                 $this->trxShortId,
1470                                 $this->pendingWriteQueryDuration( self::ESTIMATE_TOTAL ),
1471                                 $this->trxWriteAffectedRows
1472                         );
1473                 }
1474                 $this->trxLevel = 0;
1475                 $this->trxAtomicCounter = 0;
1476                 $this->trxIdleCallbacks = []; // T67263; transaction already lost
1477                 $this->trxPreCommitCallbacks = []; // T67263; transaction already lost
1478                 try {
1479                         // Handle callbacks in trxEndCallbacks, e.g. onTransactionResolution().
1480                         // If callback suppression is set then the array will remain unhandled.
1481                         $this->runOnTransactionIdleCallbacks( self::TRIGGER_ROLLBACK );
1482                 } catch ( Exception $ex ) {
1483                         // Already logged; move on...
1484                 }
1485                 try {
1486                         // Handle callbacks in trxRecurringCallbacks, e.g. setTransactionListener()
1487                         $this->runTransactionListenerCallbacks( self::TRIGGER_ROLLBACK );
1488                 } catch ( Exception $ex ) {
1489                         // Already logged; move on...
1490                 }
1491         }
1492
1493         /**
1494          * Checks whether the cause of the error is detected to be a timeout.
1495          *
1496          * It returns false by default, and not all engines support detecting this yet.
1497          * If this returns false, it will be treated as a generic query error.
1498          *
1499          * @param string $error Error text
1500          * @param int $errno Error number
1501          * @return bool
1502          */
1503         protected function wasQueryTimeout( $error, $errno ) {
1504                 return false;
1505         }
1506
1507         /**
1508          * Report a query error. Log the error, and if neither the object ignore
1509          * flag nor the $tempIgnore flag is set, throw a DBQueryError.
1510          *
1511          * @param string $error
1512          * @param int $errno
1513          * @param string $sql
1514          * @param string $fname
1515          * @param bool $tempIgnore
1516          * @throws DBQueryError
1517          */
1518         public function reportQueryError( $error, $errno, $sql, $fname, $tempIgnore = false ) {
1519                 if ( $tempIgnore ) {
1520                         $this->queryLogger->debug( "SQL ERROR (ignored): $error\n" );
1521                 } else {
1522                         $exception = $this->getQueryExceptionAndLog( $error, $errno, $sql, $fname );
1523
1524                         throw $exception;
1525                 }
1526         }
1527
1528         /**
1529          * @param string $error
1530          * @param string|int $errno
1531          * @param string $sql
1532          * @param string $fname
1533          * @return DBError
1534          */
1535         private function getQueryExceptionAndLog( $error, $errno, $sql, $fname ) {
1536                 $sql1line = mb_substr( str_replace( "\n", "\\n", $sql ), 0, 5 * 1024 );
1537                 $this->queryLogger->error(
1538                         "{fname}\t{db_server}\t{errno}\t{error}\t{sql1line}",
1539                         $this->getLogContext( [
1540                                 'method' => __METHOD__,
1541                                 'errno' => $errno,
1542                                 'error' => $error,
1543                                 'sql1line' => $sql1line,
1544                                 'fname' => $fname,
1545                                 'trace' => ( new RuntimeException() )->getTraceAsString()
1546                         ] )
1547                 );
1548                 $this->queryLogger->debug( "SQL ERROR: " . $error . "\n" );
1549                 $wasQueryTimeout = $this->wasQueryTimeout( $error, $errno );
1550                 if ( $wasQueryTimeout ) {
1551                         $e = new DBQueryTimeoutError( $this, $error, $errno, $sql, $fname );
1552                 } else {
1553                         $e = new DBQueryError( $this, $error, $errno, $sql, $fname );
1554                 }
1555
1556                 return $e;
1557         }
1558
1559         public function freeResult( $res ) {
1560         }
1561
1562         public function selectField(
1563                 $table, $var, $cond = '', $fname = __METHOD__, $options = [], $join_conds = []
1564         ) {
1565                 if ( $var === '*' ) { // sanity
1566                         throw new DBUnexpectedError( $this, "Cannot use a * field: got '$var'" );
1567                 }
1568
1569                 if ( !is_array( $options ) ) {
1570                         $options = [ $options ];
1571                 }
1572
1573                 $options['LIMIT'] = 1;
1574
1575                 $res = $this->select( $table, $var, $cond, $fname, $options, $join_conds );
1576                 if ( $res === false || !$this->numRows( $res ) ) {
1577                         return false;
1578                 }
1579
1580                 $row = $this->fetchRow( $res );
1581
1582                 if ( $row !== false ) {
1583                         return reset( $row );
1584                 } else {
1585                         return false;
1586                 }
1587         }
1588
1589         public function selectFieldValues(
1590                 $table, $var, $cond = '', $fname = __METHOD__, $options = [], $join_conds = []
1591         ) {
1592                 if ( $var === '*' ) { // sanity
1593                         throw new DBUnexpectedError( $this, "Cannot use a * field" );
1594                 } elseif ( !is_string( $var ) ) { // sanity
1595                         throw new DBUnexpectedError( $this, "Cannot use an array of fields" );
1596                 }
1597
1598                 if ( !is_array( $options ) ) {
1599                         $options = [ $options ];
1600                 }
1601
1602                 $res = $this->select( $table, [ 'value' => $var ], $cond, $fname, $options, $join_conds );
1603                 if ( $res === false ) {
1604                         return false;
1605                 }
1606
1607                 $values = [];
1608                 foreach ( $res as $row ) {
1609                         $values[] = $row->value;
1610                 }
1611
1612                 return $values;
1613         }
1614
1615         /**
1616          * Returns an optional USE INDEX clause to go after the table, and a
1617          * string to go at the end of the query.
1618          *
1619          * @param array $options Associative array of options to be turned into
1620          *   an SQL query, valid keys are listed in the function.
1621          * @return array
1622          * @see Database::select()
1623          */
1624         protected function makeSelectOptions( $options ) {
1625                 $preLimitTail = $postLimitTail = '';
1626                 $startOpts = '';
1627
1628                 $noKeyOptions = [];
1629
1630                 foreach ( $options as $key => $option ) {
1631                         if ( is_numeric( $key ) ) {
1632                                 $noKeyOptions[$option] = true;
1633                         }
1634                 }
1635
1636                 $preLimitTail .= $this->makeGroupByWithHaving( $options );
1637
1638                 $preLimitTail .= $this->makeOrderBy( $options );
1639
1640                 if ( isset( $noKeyOptions['FOR UPDATE'] ) ) {
1641                         $postLimitTail .= ' FOR UPDATE';
1642                 }
1643
1644                 if ( isset( $noKeyOptions['LOCK IN SHARE MODE'] ) ) {
1645                         $postLimitTail .= ' LOCK IN SHARE MODE';
1646                 }
1647
1648                 if ( isset( $noKeyOptions['DISTINCT'] ) || isset( $noKeyOptions['DISTINCTROW'] ) ) {
1649                         $startOpts .= 'DISTINCT';
1650                 }
1651
1652                 # Various MySQL extensions
1653                 if ( isset( $noKeyOptions['STRAIGHT_JOIN'] ) ) {
1654                         $startOpts .= ' /*! STRAIGHT_JOIN */';
1655                 }
1656
1657                 if ( isset( $noKeyOptions['HIGH_PRIORITY'] ) ) {
1658                         $startOpts .= ' HIGH_PRIORITY';
1659                 }
1660
1661                 if ( isset( $noKeyOptions['SQL_BIG_RESULT'] ) ) {
1662                         $startOpts .= ' SQL_BIG_RESULT';
1663                 }
1664
1665                 if ( isset( $noKeyOptions['SQL_BUFFER_RESULT'] ) ) {
1666                         $startOpts .= ' SQL_BUFFER_RESULT';
1667                 }
1668
1669                 if ( isset( $noKeyOptions['SQL_SMALL_RESULT'] ) ) {
1670                         $startOpts .= ' SQL_SMALL_RESULT';
1671                 }
1672
1673                 if ( isset( $noKeyOptions['SQL_CALC_FOUND_ROWS'] ) ) {
1674                         $startOpts .= ' SQL_CALC_FOUND_ROWS';
1675                 }
1676
1677                 if ( isset( $noKeyOptions['SQL_CACHE'] ) ) {
1678                         $startOpts .= ' SQL_CACHE';
1679                 }
1680
1681                 if ( isset( $noKeyOptions['SQL_NO_CACHE'] ) ) {
1682                         $startOpts .= ' SQL_NO_CACHE';
1683                 }
1684
1685                 if ( isset( $options['USE INDEX'] ) && is_string( $options['USE INDEX'] ) ) {
1686                         $useIndex = $this->useIndexClause( $options['USE INDEX'] );
1687                 } else {
1688                         $useIndex = '';
1689                 }
1690                 if ( isset( $options['IGNORE INDEX'] ) && is_string( $options['IGNORE INDEX'] ) ) {
1691                         $ignoreIndex = $this->ignoreIndexClause( $options['IGNORE INDEX'] );
1692                 } else {
1693                         $ignoreIndex = '';
1694                 }
1695
1696                 return [ $startOpts, $useIndex, $preLimitTail, $postLimitTail, $ignoreIndex ];
1697         }
1698
1699         /**
1700          * Returns an optional GROUP BY with an optional HAVING
1701          *
1702          * @param array $options Associative array of options
1703          * @return string
1704          * @see Database::select()
1705          * @since 1.21
1706          */
1707         protected function makeGroupByWithHaving( $options ) {
1708                 $sql = '';
1709                 if ( isset( $options['GROUP BY'] ) ) {
1710                         $gb = is_array( $options['GROUP BY'] )
1711                                 ? implode( ',', $options['GROUP BY'] )
1712                                 : $options['GROUP BY'];
1713                         $sql .= ' GROUP BY ' . $gb;
1714                 }
1715                 if ( isset( $options['HAVING'] ) ) {
1716                         $having = is_array( $options['HAVING'] )
1717                                 ? $this->makeList( $options['HAVING'], self::LIST_AND )
1718                                 : $options['HAVING'];
1719                         $sql .= ' HAVING ' . $having;
1720                 }
1721
1722                 return $sql;
1723         }
1724
1725         /**
1726          * Returns an optional ORDER BY
1727          *
1728          * @param array $options Associative array of options
1729          * @return string
1730          * @see Database::select()
1731          * @since 1.21
1732          */
1733         protected function makeOrderBy( $options ) {
1734                 if ( isset( $options['ORDER BY'] ) ) {
1735                         $ob = is_array( $options['ORDER BY'] )
1736                                 ? implode( ',', $options['ORDER BY'] )
1737                                 : $options['ORDER BY'];
1738
1739                         return ' ORDER BY ' . $ob;
1740                 }
1741
1742                 return '';
1743         }
1744
1745         public function select(
1746                 $table, $vars, $conds = '', $fname = __METHOD__, $options = [], $join_conds = []
1747         ) {
1748                 $sql = $this->selectSQLText( $table, $vars, $conds, $fname, $options, $join_conds );
1749
1750                 return $this->query( $sql, $fname );
1751         }
1752
1753         public function selectSQLText( $table, $vars, $conds = '', $fname = __METHOD__,
1754                 $options = [], $join_conds = []
1755         ) {
1756                 if ( is_array( $vars ) ) {
1757                         $fields = implode( ',', $this->fieldNamesWithAlias( $vars ) );
1758                 } else {
1759                         $fields = $vars;
1760                 }
1761
1762                 $options = (array)$options;
1763                 $useIndexes = ( isset( $options['USE INDEX'] ) && is_array( $options['USE INDEX'] ) )
1764                         ? $options['USE INDEX']
1765                         : [];
1766                 $ignoreIndexes = (
1767                         isset( $options['IGNORE INDEX'] ) &&
1768                         is_array( $options['IGNORE INDEX'] )
1769                 )
1770                         ? $options['IGNORE INDEX']
1771                         : [];
1772
1773                 if (
1774                         $this->selectOptionsIncludeLocking( $options ) &&
1775                         $this->selectFieldsOrOptionsAggregate( $vars, $options )
1776                 ) {
1777                         // Some DB types (postgres/oracle) disallow FOR UPDATE with aggregate
1778                         // functions. Discourage use of such queries to encourage compatibility.
1779                         call_user_func(
1780                                 $this->deprecationLogger,
1781                                 __METHOD__ . ": aggregation used with a locking SELECT ($fname)."
1782                         );
1783                 }
1784
1785                 if ( is_array( $table ) ) {
1786                         $from = ' FROM ' .
1787                                 $this->tableNamesWithIndexClauseOrJOIN(
1788                                         $table, $useIndexes, $ignoreIndexes, $join_conds );
1789                 } elseif ( $table != '' ) {
1790                         $from = ' FROM ' .
1791                                 $this->tableNamesWithIndexClauseOrJOIN(
1792                                         [ $table ], $useIndexes, $ignoreIndexes, [] );
1793                 } else {
1794                         $from = '';
1795                 }
1796
1797                 list( $startOpts, $useIndex, $preLimitTail, $postLimitTail, $ignoreIndex ) =
1798                         $this->makeSelectOptions( $options );
1799
1800                 if ( is_array( $conds ) ) {
1801                         $conds = $this->makeList( $conds, self::LIST_AND );
1802                 }
1803
1804                 if ( $conds === null || $conds === false ) {
1805                         $this->queryLogger->warning(
1806                                 __METHOD__
1807                                 . ' called from '
1808                                 . $fname
1809                                 . ' with incorrect parameters: $conds must be a string or an array'
1810                         );
1811                         $conds = '';
1812                 }
1813
1814                 if ( $conds === '' || $conds === '*' ) {
1815                         $sql = "SELECT $startOpts $fields $from $useIndex $ignoreIndex $preLimitTail";
1816                 } elseif ( is_string( $conds ) ) {
1817                         $sql = "SELECT $startOpts $fields $from $useIndex $ignoreIndex " .
1818                                 "WHERE $conds $preLimitTail";
1819                 } else {
1820                         throw new DBUnexpectedError( $this, __METHOD__ . ' called with incorrect parameters' );
1821                 }
1822
1823                 if ( isset( $options['LIMIT'] ) ) {
1824                         $sql = $this->limitResult( $sql, $options['LIMIT'],
1825                                 $options['OFFSET'] ?? false );
1826                 }
1827                 $sql = "$sql $postLimitTail";
1828
1829                 if ( isset( $options['EXPLAIN'] ) ) {
1830                         $sql = 'EXPLAIN ' . $sql;
1831                 }
1832
1833                 return $sql;
1834         }
1835
1836         public function selectRow( $table, $vars, $conds, $fname = __METHOD__,
1837                 $options = [], $join_conds = []
1838         ) {
1839                 $options = (array)$options;
1840                 $options['LIMIT'] = 1;
1841                 $res = $this->select( $table, $vars, $conds, $fname, $options, $join_conds );
1842
1843                 if ( $res === false ) {
1844                         return false;
1845                 }
1846
1847                 if ( !$this->numRows( $res ) ) {
1848                         return false;
1849                 }
1850
1851                 $obj = $this->fetchObject( $res );
1852
1853                 return $obj;
1854         }
1855
1856         public function estimateRowCount(
1857                 $table, $var = '*', $conds = '', $fname = __METHOD__, $options = [], $join_conds = []
1858         ) {
1859                 $conds = $this->normalizeConditions( $conds, $fname );
1860                 $column = $this->extractSingleFieldFromList( $var );
1861                 if ( is_string( $column ) && !in_array( $column, [ '*', '1' ] ) ) {
1862                         $conds[] = "$column IS NOT NULL";
1863                 }
1864
1865                 $res = $this->select(
1866                         $table, [ 'rowcount' => 'COUNT(*)' ], $conds, $fname, $options, $join_conds
1867                 );
1868                 $row = $res ? $this->fetchRow( $res ) : [];
1869
1870                 return isset( $row['rowcount'] ) ? (int)$row['rowcount'] : 0;
1871         }
1872
1873         public function selectRowCount(
1874                 $tables, $var = '*', $conds = '', $fname = __METHOD__, $options = [], $join_conds = []
1875         ) {
1876                 $conds = $this->normalizeConditions( $conds, $fname );
1877                 $column = $this->extractSingleFieldFromList( $var );
1878                 if ( is_string( $column ) && !in_array( $column, [ '*', '1' ] ) ) {
1879                         $conds[] = "$column IS NOT NULL";
1880                 }
1881
1882                 $res = $this->select(
1883                         [
1884                                 'tmp_count' => $this->buildSelectSubquery(
1885                                         $tables,
1886                                         '1',
1887                                         $conds,
1888                                         $fname,
1889                                         $options,
1890                                         $join_conds
1891                                 )
1892                         ],
1893                         [ 'rowcount' => 'COUNT(*)' ],
1894                         [],
1895                         $fname
1896                 );
1897                 $row = $res ? $this->fetchRow( $res ) : [];
1898
1899                 return isset( $row['rowcount'] ) ? (int)$row['rowcount'] : 0;
1900         }
1901
1902         /**
1903          * @param string|array $options
1904          * @return bool
1905          */
1906         private function selectOptionsIncludeLocking( $options ) {
1907                 $options = (array)$options;
1908                 foreach ( [ 'FOR UPDATE', 'LOCK IN SHARE MODE' ] as $lock ) {
1909                         if ( in_array( $lock, $options, true ) ) {
1910                                 return true;
1911                         }
1912                 }
1913
1914                 return false;
1915         }
1916
1917         /**
1918          * @param array|string $fields
1919          * @param array|string $options
1920          * @return bool
1921          */
1922         private function selectFieldsOrOptionsAggregate( $fields, $options ) {
1923                 foreach ( (array)$options as $key => $value ) {
1924                         if ( is_string( $key ) ) {
1925                                 if ( preg_match( '/^(?:GROUP BY|HAVING)$/i', $key ) ) {
1926                                         return true;
1927                                 }
1928                         } elseif ( is_string( $value ) ) {
1929                                 if ( preg_match( '/^(?:DISTINCT|DISTINCTROW)$/i', $value ) ) {
1930                                         return true;
1931                                 }
1932                         }
1933                 }
1934
1935                 $regex = '/^(?:COUNT|MIN|MAX|SUM|GROUP_CONCAT|LISTAGG|ARRAY_AGG)\s*\\(/i';
1936                 foreach ( (array)$fields as $field ) {
1937                         if ( is_string( $field ) && preg_match( $regex, $field ) ) {
1938                                 return true;
1939                         }
1940                 }
1941
1942                 return false;
1943         }
1944
1945         /**
1946          * @param array|string $conds
1947          * @param string $fname
1948          * @return array
1949          */
1950         final protected function normalizeConditions( $conds, $fname ) {
1951                 if ( $conds === null || $conds === false ) {
1952                         $this->queryLogger->warning(
1953                                 __METHOD__
1954                                 . ' called from '
1955                                 . $fname
1956                                 . ' with incorrect parameters: $conds must be a string or an array'
1957                         );
1958                         $conds = '';
1959                 }
1960
1961                 if ( !is_array( $conds ) ) {
1962                         $conds = ( $conds === '' ) ? [] : [ $conds ];
1963                 }
1964
1965                 return $conds;
1966         }
1967
1968         /**
1969          * @param array|string $var Field parameter in the style of select()
1970          * @return string|null Column name or null; ignores aliases
1971          * @throws DBUnexpectedError Errors out if multiple columns are given
1972          */
1973         final protected function extractSingleFieldFromList( $var ) {
1974                 if ( is_array( $var ) ) {
1975                         if ( !$var ) {
1976                                 $column = null;
1977                         } elseif ( count( $var ) == 1 ) {
1978                                 $column = $var[0] ?? reset( $var );
1979                         } else {
1980                                 throw new DBUnexpectedError( $this, __METHOD__ . ': got multiple columns.' );
1981                         }
1982                 } else {
1983                         $column = $var;
1984                 }
1985
1986                 return $column;
1987         }
1988
1989         public function lockForUpdate(
1990                 $table, $conds = '', $fname = __METHOD__, $options = [], $join_conds = []
1991         ) {
1992                 if ( !$this->trxLevel && !$this->getFlag( self::DBO_TRX ) ) {
1993                         throw new DBUnexpectedError(
1994                                 $this,
1995                                 __METHOD__ . ': no transaction is active nor is DBO_TRX set'
1996                         );
1997                 }
1998
1999                 $options = (array)$options;
2000                 $options[] = 'FOR UPDATE';
2001
2002                 return $this->selectRowCount( $table, '*', $conds, $fname, $options, $join_conds );
2003         }
2004
2005         /**
2006          * Removes most variables from an SQL query and replaces them with X or N for numbers.
2007          * It's only slightly flawed. Don't use for anything important.
2008          *
2009          * @param string $sql A SQL Query
2010          *
2011          * @return string
2012          */
2013         protected static function generalizeSQL( $sql ) {
2014                 # This does the same as the regexp below would do, but in such a way
2015                 # as to avoid crashing php on some large strings.
2016                 # $sql = preg_replace( "/'([^\\\\']|\\\\.)*'|\"([^\\\\\"]|\\\\.)*\"/", "'X'", $sql );
2017
2018                 $sql = str_replace( "\\\\", '', $sql );
2019                 $sql = str_replace( "\\'", '', $sql );
2020                 $sql = str_replace( "\\\"", '', $sql );
2021                 $sql = preg_replace( "/'.*'/s", "'X'", $sql );
2022                 $sql = preg_replace( '/".*"/s', "'X'", $sql );
2023
2024                 # All newlines, tabs, etc replaced by single space
2025                 $sql = preg_replace( '/\s+/', ' ', $sql );
2026
2027                 # All numbers => N,
2028                 # except the ones surrounded by characters, e.g. l10n
2029                 $sql = preg_replace( '/-?\d+(,-?\d+)+/s', 'N,...,N', $sql );
2030                 $sql = preg_replace( '/(?<![a-zA-Z])-?\d+(?![a-zA-Z])/s', 'N', $sql );
2031
2032                 return $sql;
2033         }
2034
2035         public function fieldExists( $table, $field, $fname = __METHOD__ ) {
2036                 $info = $this->fieldInfo( $table, $field );
2037
2038                 return (bool)$info;
2039         }
2040
2041         public function indexExists( $table, $index, $fname = __METHOD__ ) {
2042                 if ( !$this->tableExists( $table ) ) {
2043                         return null;
2044                 }
2045
2046                 $info = $this->indexInfo( $table, $index, $fname );
2047                 if ( is_null( $info ) ) {
2048                         return null;
2049                 } else {
2050                         return $info !== false;
2051                 }
2052         }
2053
2054         abstract public function tableExists( $table, $fname = __METHOD__ );
2055
2056         public function indexUnique( $table, $index ) {
2057                 $indexInfo = $this->indexInfo( $table, $index );
2058
2059                 if ( !$indexInfo ) {
2060                         return null;
2061                 }
2062
2063                 return !$indexInfo[0]->Non_unique;
2064         }
2065
2066         /**
2067          * Helper for Database::insert().
2068          *
2069          * @param array $options
2070          * @return string
2071          */
2072         protected function makeInsertOptions( $options ) {
2073                 return implode( ' ', $options );
2074         }
2075
2076         public function insert( $table, $a, $fname = __METHOD__, $options = [] ) {
2077                 # No rows to insert, easy just return now
2078                 if ( !count( $a ) ) {
2079                         return true;
2080                 }
2081
2082                 $table = $this->tableName( $table );
2083
2084                 if ( !is_array( $options ) ) {
2085                         $options = [ $options ];
2086                 }
2087
2088                 $options = $this->makeInsertOptions( $options );
2089
2090                 if ( isset( $a[0] ) && is_array( $a[0] ) ) {
2091                         $multi = true;
2092                         $keys = array_keys( $a[0] );
2093                 } else {
2094                         $multi = false;
2095                         $keys = array_keys( $a );
2096                 }
2097
2098                 $sql = 'INSERT ' . $options .
2099                         " INTO $table (" . implode( ',', $keys ) . ') VALUES ';
2100
2101                 if ( $multi ) {
2102                         $first = true;
2103                         foreach ( $a as $row ) {
2104                                 if ( $first ) {
2105                                         $first = false;
2106                                 } else {
2107                                         $sql .= ',';
2108                                 }
2109                                 $sql .= '(' . $this->makeList( $row ) . ')';
2110                         }
2111                 } else {
2112                         $sql .= '(' . $this->makeList( $a ) . ')';
2113                 }
2114
2115                 $this->query( $sql, $fname );
2116
2117                 return true;
2118         }
2119
2120         /**
2121          * Make UPDATE options array for Database::makeUpdateOptions
2122          *
2123          * @param array $options
2124          * @return array
2125          */
2126         protected function makeUpdateOptionsArray( $options ) {
2127                 if ( !is_array( $options ) ) {
2128                         $options = [ $options ];
2129                 }
2130
2131                 $opts = [];
2132
2133                 if ( in_array( 'IGNORE', $options ) ) {
2134                         $opts[] = 'IGNORE';
2135                 }
2136
2137                 return $opts;
2138         }
2139
2140         /**
2141          * Make UPDATE options for the Database::update function
2142          *
2143          * @param array $options The options passed to Database::update
2144          * @return string
2145          */
2146         protected function makeUpdateOptions( $options ) {
2147                 $opts = $this->makeUpdateOptionsArray( $options );
2148
2149                 return implode( ' ', $opts );
2150         }
2151
2152         public function update( $table, $values, $conds, $fname = __METHOD__, $options = [] ) {
2153                 $table = $this->tableName( $table );
2154                 $opts = $this->makeUpdateOptions( $options );
2155                 $sql = "UPDATE $opts $table SET " . $this->makeList( $values, self::LIST_SET );
2156
2157                 if ( $conds !== [] && $conds !== '*' ) {
2158                         $sql .= " WHERE " . $this->makeList( $conds, self::LIST_AND );
2159                 }
2160
2161                 $this->query( $sql, $fname );
2162
2163                 return true;
2164         }
2165
2166         public function makeList( $a, $mode = self::LIST_COMMA ) {
2167                 if ( !is_array( $a ) ) {
2168                         throw new DBUnexpectedError( $this, __METHOD__ . ' called with incorrect parameters' );
2169                 }
2170
2171                 $first = true;
2172                 $list = '';
2173
2174                 foreach ( $a as $field => $value ) {
2175                         if ( !$first ) {
2176                                 if ( $mode == self::LIST_AND ) {
2177                                         $list .= ' AND ';
2178                                 } elseif ( $mode == self::LIST_OR ) {
2179                                         $list .= ' OR ';
2180                                 } else {
2181                                         $list .= ',';
2182                                 }
2183                         } else {
2184                                 $first = false;
2185                         }
2186
2187                         if ( ( $mode == self::LIST_AND || $mode == self::LIST_OR ) && is_numeric( $field ) ) {
2188                                 $list .= "($value)";
2189                         } elseif ( $mode == self::LIST_SET && is_numeric( $field ) ) {
2190                                 $list .= "$value";
2191                         } elseif (
2192                                 ( $mode == self::LIST_AND || $mode == self::LIST_OR ) && is_array( $value )
2193                         ) {
2194                                 // Remove null from array to be handled separately if found
2195                                 $includeNull = false;
2196                                 foreach ( array_keys( $value, null, true ) as $nullKey ) {
2197                                         $includeNull = true;
2198                                         unset( $value[$nullKey] );
2199                                 }
2200                                 if ( count( $value ) == 0 && !$includeNull ) {
2201                                         throw new InvalidArgumentException(
2202                                                 __METHOD__ . ": empty input for field $field" );
2203                                 } elseif ( count( $value ) == 0 ) {
2204                                         // only check if $field is null
2205                                         $list .= "$field IS NULL";
2206                                 } else {
2207                                         // IN clause contains at least one valid element
2208                                         if ( $includeNull ) {
2209                                                 // Group subconditions to ensure correct precedence
2210                                                 $list .= '(';
2211                                         }
2212                                         if ( count( $value ) == 1 ) {
2213                                                 // Special-case single values, as IN isn't terribly efficient
2214                                                 // Don't necessarily assume the single key is 0; we don't
2215                                                 // enforce linear numeric ordering on other arrays here.
2216                                                 $value = array_values( $value )[0];
2217                                                 $list .= $field . " = " . $this->addQuotes( $value );
2218                                         } else {
2219                                                 $list .= $field . " IN (" . $this->makeList( $value ) . ") ";
2220                                         }
2221                                         // if null present in array, append IS NULL
2222                                         if ( $includeNull ) {
2223                                                 $list .= " OR $field IS NULL)";
2224                                         }
2225                                 }
2226                         } elseif ( $value === null ) {
2227                                 if ( $mode == self::LIST_AND || $mode == self::LIST_OR ) {
2228                                         $list .= "$field IS ";
2229                                 } elseif ( $mode == self::LIST_SET ) {
2230                                         $list .= "$field = ";
2231                                 }
2232                                 $list .= 'NULL';
2233                         } else {
2234                                 if (
2235                                         $mode == self::LIST_AND || $mode == self::LIST_OR || $mode == self::LIST_SET
2236                                 ) {
2237                                         $list .= "$field = ";
2238                                 }
2239                                 $list .= $mode == self::LIST_NAMES ? $value : $this->addQuotes( $value );
2240                         }
2241                 }
2242
2243                 return $list;
2244         }
2245
2246         public function makeWhereFrom2d( $data, $baseKey, $subKey ) {
2247                 $conds = [];
2248
2249                 foreach ( $data as $base => $sub ) {
2250                         if ( count( $sub ) ) {
2251                                 $conds[] = $this->makeList(
2252                                         [ $baseKey => $base, $subKey => array_keys( $sub ) ],
2253                                         self::LIST_AND );
2254                         }
2255                 }
2256
2257                 if ( $conds ) {
2258                         return $this->makeList( $conds, self::LIST_OR );
2259                 } else {
2260                         // Nothing to search for...
2261                         return false;
2262                 }
2263         }
2264
2265         public function aggregateValue( $valuedata, $valuename = 'value' ) {
2266                 return $valuename;
2267         }
2268
2269         public function bitNot( $field ) {
2270                 return "(~$field)";
2271         }
2272
2273         public function bitAnd( $fieldLeft, $fieldRight ) {
2274                 return "($fieldLeft & $fieldRight)";
2275         }
2276
2277         public function bitOr( $fieldLeft, $fieldRight ) {
2278                 return "($fieldLeft | $fieldRight)";
2279         }
2280
2281         public function buildConcat( $stringList ) {
2282                 return 'CONCAT(' . implode( ',', $stringList ) . ')';
2283         }
2284
2285         public function buildGroupConcatField(
2286                 $delim, $table, $field, $conds = '', $join_conds = []
2287         ) {
2288                 $fld = "GROUP_CONCAT($field SEPARATOR " . $this->addQuotes( $delim ) . ')';
2289
2290                 return '(' . $this->selectSQLText( $table, $fld, $conds, null, [], $join_conds ) . ')';
2291         }
2292
2293         public function buildSubstring( $input, $startPosition, $length = null ) {
2294                 $this->assertBuildSubstringParams( $startPosition, $length );
2295                 $functionBody = "$input FROM $startPosition";
2296                 if ( $length !== null ) {
2297                         $functionBody .= " FOR $length";
2298                 }
2299                 return 'SUBSTRING(' . $functionBody . ')';
2300         }
2301
2302         /**
2303          * Check type and bounds for parameters to self::buildSubstring()
2304          *
2305          * All supported databases have substring functions that behave the same for
2306          * positive $startPosition and non-negative $length, but behaviors differ when
2307          * given 0 or negative $startPosition or negative $length. The simplest
2308          * solution to that is to just forbid those values.
2309          *
2310          * @param int $startPosition
2311          * @param int|null $length
2312          * @since 1.31
2313          */
2314         protected function assertBuildSubstringParams( $startPosition, $length ) {
2315                 if ( !is_int( $startPosition ) || $startPosition <= 0 ) {
2316                         throw new InvalidArgumentException(
2317                                 '$startPosition must be a positive integer'
2318                         );
2319                 }
2320                 if ( !( is_int( $length ) && $length >= 0 || $length === null ) ) {
2321                         throw new InvalidArgumentException(
2322                                 '$length must be null or an integer greater than or equal to 0'
2323                         );
2324                 }
2325         }
2326
2327         public function buildStringCast( $field ) {
2328                 // In theory this should work for any standards-compliant
2329                 // SQL implementation, although it may not be the best way to do it.
2330                 return "CAST( $field AS CHARACTER )";
2331         }
2332
2333         public function buildIntegerCast( $field ) {
2334                 return 'CAST( ' . $field . ' AS INTEGER )';
2335         }
2336
2337         public function buildSelectSubquery(
2338                 $table, $vars, $conds = '', $fname = __METHOD__,
2339                 $options = [], $join_conds = []
2340         ) {
2341                 return new Subquery(
2342                         $this->selectSQLText( $table, $vars, $conds, $fname, $options, $join_conds )
2343                 );
2344         }
2345
2346         public function databasesAreIndependent() {
2347                 return false;
2348         }
2349
2350         final public function selectDB( $db ) {
2351                 $this->selectDomain( new DatabaseDomain(
2352                         $db,
2353                         $this->currentDomain->getSchema(),
2354                         $this->currentDomain->getTablePrefix()
2355                 ) );
2356
2357                 return true;
2358         }
2359
2360         final public function selectDomain( $domain ) {
2361                 $this->doSelectDomain( DatabaseDomain::newFromId( $domain ) );
2362         }
2363
2364         protected function doSelectDomain( DatabaseDomain $domain ) {
2365                 $this->currentDomain = $domain;
2366         }
2367
2368         public function getDBname() {
2369                 return $this->currentDomain->getDatabase();
2370         }
2371
2372         public function getServer() {
2373                 return $this->server;
2374         }
2375
2376         public function tableName( $name, $format = 'quoted' ) {
2377                 if ( $name instanceof Subquery ) {
2378                         throw new DBUnexpectedError(
2379                                 $this,
2380                                 __METHOD__ . ': got Subquery instance when expecting a string.'
2381                         );
2382                 }
2383
2384                 # Skip the entire process when we have a string quoted on both ends.
2385                 # Note that we check the end so that we will still quote any use of
2386                 # use of `database`.table. But won't break things if someone wants
2387                 # to query a database table with a dot in the name.
2388                 if ( $this->isQuotedIdentifier( $name ) ) {
2389                         return $name;
2390                 }
2391
2392                 # Lets test for any bits of text that should never show up in a table
2393                 # name. Basically anything like JOIN or ON which are actually part of
2394                 # SQL queries, but may end up inside of the table value to combine
2395                 # sql. Such as how the API is doing.
2396                 # Note that we use a whitespace test rather than a \b test to avoid
2397                 # any remote case where a word like on may be inside of a table name
2398                 # surrounded by symbols which may be considered word breaks.
2399                 if ( preg_match( '/(^|\s)(DISTINCT|JOIN|ON|AS)(\s|$)/i', $name ) !== 0 ) {
2400                         $this->queryLogger->warning(
2401                                 __METHOD__ . ": use of subqueries is not supported this way.",
2402                                 [ 'trace' => ( new RuntimeException() )->getTraceAsString() ]
2403                         );
2404
2405                         return $name;
2406                 }
2407
2408                 # Split database and table into proper variables.
2409                 list( $database, $schema, $prefix, $table ) = $this->qualifiedTableComponents( $name );
2410
2411                 # Quote $table and apply the prefix if not quoted.
2412                 # $tableName might be empty if this is called from Database::replaceVars()
2413                 $tableName = "{$prefix}{$table}";
2414                 if ( $format === 'quoted'
2415                         && !$this->isQuotedIdentifier( $tableName )
2416                         && $tableName !== ''
2417                 ) {
2418                         $tableName = $this->addIdentifierQuotes( $tableName );
2419                 }
2420
2421                 # Quote $schema and $database and merge them with the table name if needed
2422                 $tableName = $this->prependDatabaseOrSchema( $schema, $tableName, $format );
2423                 $tableName = $this->prependDatabaseOrSchema( $database, $tableName, $format );
2424
2425                 return $tableName;
2426         }
2427
2428         /**
2429          * Get the table components needed for a query given the currently selected database
2430          *
2431          * @param string $name Table name in the form of db.schema.table, db.table, or table
2432          * @return array (DB name or "" for default, schema name, table prefix, table name)
2433          */
2434         protected function qualifiedTableComponents( $name ) {
2435                 # We reverse the explode so that database.table and table both output the correct table.
2436                 $dbDetails = explode( '.', $name, 3 );
2437                 if ( count( $dbDetails ) == 3 ) {
2438                         list( $database, $schema, $table ) = $dbDetails;
2439                         # We don't want any prefix added in this case
2440                         $prefix = '';
2441                 } elseif ( count( $dbDetails ) == 2 ) {
2442                         list( $database, $table ) = $dbDetails;
2443                         # We don't want any prefix added in this case
2444                         $prefix = '';
2445                         # In dbs that support it, $database may actually be the schema
2446                         # but that doesn't affect any of the functionality here
2447                         $schema = '';
2448                 } else {
2449                         list( $table ) = $dbDetails;
2450                         if ( isset( $this->tableAliases[$table] ) ) {
2451                                 $database = $this->tableAliases[$table]['dbname'];
2452                                 $schema = is_string( $this->tableAliases[$table]['schema'] )
2453                                         ? $this->tableAliases[$table]['schema']
2454                                         : $this->relationSchemaQualifier();
2455                                 $prefix = is_string( $this->tableAliases[$table]['prefix'] )
2456                                         ? $this->tableAliases[$table]['prefix']
2457                                         : $this->tablePrefix();
2458                         } else {
2459                                 $database = '';
2460                                 $schema = $this->relationSchemaQualifier(); # Default schema
2461                                 $prefix = $this->tablePrefix(); # Default prefix
2462                         }
2463                 }
2464
2465                 return [ $database, $schema, $prefix, $table ];
2466         }
2467
2468         /**
2469          * @param string|null $namespace Database or schema
2470          * @param string $relation Name of table, view, sequence, etc...
2471          * @param string $format One of (raw, quoted)
2472          * @return string Relation name with quoted and merged $namespace as needed
2473          */
2474         private function prependDatabaseOrSchema( $namespace, $relation, $format ) {
2475                 if ( strlen( $namespace ) ) {
2476                         if ( $format === 'quoted' && !$this->isQuotedIdentifier( $namespace ) ) {
2477                                 $namespace = $this->addIdentifierQuotes( $namespace );
2478                         }
2479                         $relation = $namespace . '.' . $relation;
2480                 }
2481
2482                 return $relation;
2483         }
2484
2485         public function tableNames() {
2486                 $inArray = func_get_args();
2487                 $retVal = [];
2488
2489                 foreach ( $inArray as $name ) {
2490                         $retVal[$name] = $this->tableName( $name );
2491                 }
2492
2493                 return $retVal;
2494         }
2495
2496         public function tableNamesN() {
2497                 $inArray = func_get_args();
2498                 $retVal = [];
2499
2500                 foreach ( $inArray as $name ) {
2501                         $retVal[] = $this->tableName( $name );
2502                 }
2503
2504                 return $retVal;
2505         }
2506
2507         /**
2508          * Get an aliased table name
2509          *
2510          * This returns strings like "tableName AS newTableName" for aliased tables
2511          * and "(SELECT * from tableA) newTablename" for subqueries (e.g. derived tables)
2512          *
2513          * @see Database::tableName()
2514          * @param string|Subquery $table Table name or object with a 'sql' field
2515          * @param string|bool $alias Table alias (optional)
2516          * @return string SQL name for aliased table. Will not alias a table to its own name
2517          */
2518         protected function tableNameWithAlias( $table, $alias = false ) {
2519                 if ( is_string( $table ) ) {
2520                         $quotedTable = $this->tableName( $table );
2521                 } elseif ( $table instanceof Subquery ) {
2522                         $quotedTable = (string)$table;
2523                 } else {
2524                         throw new InvalidArgumentException( "Table must be a string or Subquery." );
2525                 }
2526
2527                 if ( !strlen( $alias ) || $alias === $table ) {
2528                         if ( $table instanceof Subquery ) {
2529                                 throw new InvalidArgumentException( "Subquery table missing alias." );
2530                         }
2531
2532                         return $quotedTable;
2533                 } else {
2534                         return $quotedTable . ' ' . $this->addIdentifierQuotes( $alias );
2535                 }
2536         }
2537
2538         /**
2539          * Gets an array of aliased table names
2540          *
2541          * @param array $tables [ [alias] => table ]
2542          * @return string[] See tableNameWithAlias()
2543          */
2544         protected function tableNamesWithAlias( $tables ) {
2545                 $retval = [];
2546                 foreach ( $tables as $alias => $table ) {
2547                         if ( is_numeric( $alias ) ) {
2548                                 $alias = $table;
2549                         }
2550                         $retval[] = $this->tableNameWithAlias( $table, $alias );
2551                 }
2552
2553                 return $retval;
2554         }
2555
2556         /**
2557          * Get an aliased field name
2558          * e.g. fieldName AS newFieldName
2559          *
2560          * @param string $name Field name
2561          * @param string|bool $alias Alias (optional)
2562          * @return string SQL name for aliased field. Will not alias a field to its own name
2563          */
2564         protected function fieldNameWithAlias( $name, $alias = false ) {
2565                 if ( !$alias || (string)$alias === (string)$name ) {
2566                         return $name;
2567                 } else {
2568                         return $name . ' AS ' . $this->addIdentifierQuotes( $alias ); // PostgreSQL needs AS
2569                 }
2570         }
2571
2572         /**
2573          * Gets an array of aliased field names
2574          *
2575          * @param array $fields [ [alias] => field ]
2576          * @return string[] See fieldNameWithAlias()
2577          */
2578         protected function fieldNamesWithAlias( $fields ) {
2579                 $retval = [];
2580                 foreach ( $fields as $alias => $field ) {
2581                         if ( is_numeric( $alias ) ) {
2582                                 $alias = $field;
2583                         }
2584                         $retval[] = $this->fieldNameWithAlias( $field, $alias );
2585                 }
2586
2587                 return $retval;
2588         }
2589
2590         /**
2591          * Get the aliased table name clause for a FROM clause
2592          * which might have a JOIN and/or USE INDEX or IGNORE INDEX clause
2593          *
2594          * @param array $tables ( [alias] => table )
2595          * @param array $use_index Same as for select()
2596          * @param array $ignore_index Same as for select()
2597          * @param array $join_conds Same as for select()
2598          * @return string
2599          */
2600         protected function tableNamesWithIndexClauseOrJOIN(
2601                 $tables, $use_index = [], $ignore_index = [], $join_conds = []
2602         ) {
2603                 $ret = [];
2604                 $retJOIN = [];
2605                 $use_index = (array)$use_index;
2606                 $ignore_index = (array)$ignore_index;
2607                 $join_conds = (array)$join_conds;
2608
2609                 foreach ( $tables as $alias => $table ) {
2610                         if ( !is_string( $alias ) ) {
2611                                 // No alias? Set it equal to the table name
2612                                 $alias = $table;
2613                         }
2614
2615                         if ( is_array( $table ) ) {
2616                                 // A parenthesized group
2617                                 if ( count( $table ) > 1 ) {
2618                                         $joinedTable = '(' .
2619                                                 $this->tableNamesWithIndexClauseOrJOIN(
2620                                                         $table, $use_index, $ignore_index, $join_conds ) . ')';
2621                                 } else {
2622                                         // Degenerate case
2623                                         $innerTable = reset( $table );
2624                                         $innerAlias = key( $table );
2625                                         $joinedTable = $this->tableNameWithAlias(
2626                                                 $innerTable,
2627                                                 is_string( $innerAlias ) ? $innerAlias : $innerTable
2628                                         );
2629                                 }
2630                         } else {
2631                                 $joinedTable = $this->tableNameWithAlias( $table, $alias );
2632                         }
2633
2634                         // Is there a JOIN clause for this table?
2635                         if ( isset( $join_conds[$alias] ) ) {
2636                                 list( $joinType, $conds ) = $join_conds[$alias];
2637                                 $tableClause = $joinType;
2638                                 $tableClause .= ' ' . $joinedTable;
2639                                 if ( isset( $use_index[$alias] ) ) { // has USE INDEX?
2640                                         $use = $this->useIndexClause( implode( ',', (array)$use_index[$alias] ) );
2641                                         if ( $use != '' ) {
2642                                                 $tableClause .= ' ' . $use;
2643                                         }
2644                                 }
2645                                 if ( isset( $ignore_index[$alias] ) ) { // has IGNORE INDEX?
2646                                         $ignore = $this->ignoreIndexClause(
2647                                                 implode( ',', (array)$ignore_index[$alias] ) );
2648                                         if ( $ignore != '' ) {
2649                                                 $tableClause .= ' ' . $ignore;
2650                                         }
2651                                 }
2652                                 $on = $this->makeList( (array)$conds, self::LIST_AND );
2653                                 if ( $on != '' ) {
2654                                         $tableClause .= ' ON (' . $on . ')';
2655                                 }
2656
2657                                 $retJOIN[] = $tableClause;
2658                         } elseif ( isset( $use_index[$alias] ) ) {
2659                                 // Is there an INDEX clause for this table?
2660                                 $tableClause = $joinedTable;
2661                                 $tableClause .= ' ' . $this->useIndexClause(
2662                                                 implode( ',', (array)$use_index[$alias] )
2663                                         );
2664
2665                                 $ret[] = $tableClause;
2666                         } elseif ( isset( $ignore_index[$alias] ) ) {
2667                                 // Is there an INDEX clause for this table?
2668                                 $tableClause = $joinedTable;
2669                                 $tableClause .= ' ' . $this->ignoreIndexClause(
2670                                                 implode( ',', (array)$ignore_index[$alias] )
2671                                         );
2672
2673                                 $ret[] = $tableClause;
2674                         } else {
2675                                 $tableClause = $joinedTable;
2676
2677                                 $ret[] = $tableClause;
2678                         }
2679                 }
2680
2681                 // We can't separate explicit JOIN clauses with ',', use ' ' for those
2682                 $implicitJoins = $ret ? implode( ',', $ret ) : "";
2683                 $explicitJoins = $retJOIN ? implode( ' ', $retJOIN ) : "";
2684
2685                 // Compile our final table clause
2686                 return implode( ' ', [ $implicitJoins, $explicitJoins ] );
2687         }
2688
2689         /**
2690          * Allows for index remapping in queries where this is not consistent across DBMS
2691          *
2692          * @param string $index
2693          * @return string
2694          */
2695         protected function indexName( $index ) {
2696                 return $this->indexAliases[$index] ?? $index;
2697         }
2698
2699         public function addQuotes( $s ) {
2700                 if ( $s instanceof Blob ) {
2701                         $s = $s->fetch();
2702                 }
2703                 if ( $s === null ) {
2704                         return 'NULL';
2705                 } elseif ( is_bool( $s ) ) {
2706                         return (int)$s;
2707                 } else {
2708                         # This will also quote numeric values. This should be harmless,
2709                         # and protects against weird problems that occur when they really
2710                         # _are_ strings such as article titles and string->number->string
2711                         # conversion is not 1:1.
2712                         return "'" . $this->strencode( $s ) . "'";
2713                 }
2714         }
2715
2716         public function addIdentifierQuotes( $s ) {
2717                 return '"' . str_replace( '"', '""', $s ) . '"';
2718         }
2719
2720         /**
2721          * Returns if the given identifier looks quoted or not according to
2722          * the database convention for quoting identifiers .
2723          *
2724          * @note Do not use this to determine if untrusted input is safe.
2725          *   A malicious user can trick this function.
2726          * @param string $name
2727          * @return bool
2728          */
2729         public function isQuotedIdentifier( $name ) {
2730                 return $name[0] == '"' && substr( $name, -1, 1 ) == '"';
2731         }
2732
2733         /**
2734          * @param string $s
2735          * @param string $escapeChar
2736          * @return string
2737          */
2738         protected function escapeLikeInternal( $s, $escapeChar = '`' ) {
2739                 return str_replace( [ $escapeChar, '%', '_' ],
2740                         [ "{$escapeChar}{$escapeChar}", "{$escapeChar}%", "{$escapeChar}_" ],
2741                         $s );
2742         }
2743
2744         public function buildLike() {
2745                 $params = func_get_args();
2746
2747                 if ( count( $params ) > 0 && is_array( $params[0] ) ) {
2748                         $params = $params[0];
2749                 }
2750
2751                 $s = '';
2752
2753                 // We use ` instead of \ as the default LIKE escape character, since addQuotes()
2754                 // may escape backslashes, creating problems of double escaping. The `
2755                 // character has good cross-DBMS compatibility, avoiding special operators
2756                 // in MS SQL like ^ and %
2757                 $escapeChar = '`';
2758
2759                 foreach ( $params as $value ) {
2760                         if ( $value instanceof LikeMatch ) {
2761                                 $s .= $value->toString();
2762                         } else {
2763                                 $s .= $this->escapeLikeInternal( $value, $escapeChar );
2764                         }
2765                 }
2766
2767                 return ' LIKE ' .
2768                         $this->addQuotes( $s ) . ' ESCAPE ' . $this->addQuotes( $escapeChar ) . ' ';
2769         }
2770
2771         public function anyChar() {
2772                 return new LikeMatch( '_' );
2773         }
2774
2775         public function anyString() {
2776                 return new LikeMatch( '%' );
2777         }
2778
2779         public function nextSequenceValue( $seqName ) {
2780                 return null;
2781         }
2782
2783         /**
2784          * USE INDEX clause. Unlikely to be useful for anything but MySQL. This
2785          * is only needed because a) MySQL must be as efficient as possible due to
2786          * its use on Wikipedia, and b) MySQL 4.0 is kind of dumb sometimes about
2787          * which index to pick. Anyway, other databases might have different
2788          * indexes on a given table. So don't bother overriding this unless you're
2789          * MySQL.
2790          * @param string $index
2791          * @return string
2792          */
2793         public function useIndexClause( $index ) {
2794                 return '';
2795         }
2796
2797         /**
2798          * IGNORE INDEX clause. Unlikely to be useful for anything but MySQL. This
2799          * is only needed because a) MySQL must be as efficient as possible due to
2800          * its use on Wikipedia, and b) MySQL 4.0 is kind of dumb sometimes about
2801          * which index to pick. Anyway, other databases might have different
2802          * indexes on a given table. So don't bother overriding this unless you're
2803          * MySQL.
2804          * @param string $index
2805          * @return string
2806          */
2807         public function ignoreIndexClause( $index ) {
2808                 return '';
2809         }
2810
2811         public function replace( $table, $uniqueIndexes, $rows, $fname = __METHOD__ ) {
2812                 if ( count( $rows ) == 0 ) {
2813                         return;
2814                 }
2815
2816                 $uniqueIndexes = (array)$uniqueIndexes;
2817                 // Single row case
2818                 if ( !is_array( reset( $rows ) ) ) {
2819                         $rows = [ $rows ];
2820                 }
2821
2822                 try {
2823                         $this->startAtomic( $fname, self::ATOMIC_CANCELABLE );
2824                         $affectedRowCount = 0;
2825                         foreach ( $rows as $row ) {
2826                                 // Delete rows which collide with this one
2827                                 $indexWhereClauses = [];
2828                                 foreach ( $uniqueIndexes as $index ) {
2829                                         $indexColumns = (array)$index;
2830                                         $indexRowValues = array_intersect_key( $row, array_flip( $indexColumns ) );
2831                                         if ( count( $indexRowValues ) != count( $indexColumns ) ) {
2832                                                 throw new DBUnexpectedError(
2833                                                         $this,
2834                                                         'New record does not provide all values for unique key (' .
2835                                                         implode( ', ', $indexColumns ) . ')'
2836                                                 );
2837                                         } elseif ( in_array( null, $indexRowValues, true ) ) {
2838                                                 throw new DBUnexpectedError(
2839                                                         $this,
2840                                                         'New record has a null value for unique key (' .
2841                                                         implode( ', ', $indexColumns ) . ')'
2842                                                 );
2843                                         }
2844                                         $indexWhereClauses[] = $this->makeList( $indexRowValues, LIST_AND );
2845                                 }
2846
2847                                 if ( $indexWhereClauses ) {
2848                                         $this->delete( $table, $this->makeList( $indexWhereClauses, LIST_OR ), $fname );
2849                                         $affectedRowCount += $this->affectedRows();
2850                                 }
2851
2852                                 // Now insert the row
2853                                 $this->insert( $table, $row, $fname );
2854                                 $affectedRowCount += $this->affectedRows();
2855                         }
2856                         $this->endAtomic( $fname );
2857                         $this->affectedRowCount = $affectedRowCount;
2858                 } catch ( Exception $e ) {
2859                         $this->cancelAtomic( $fname );
2860                         throw $e;
2861                 }
2862         }
2863
2864         /**
2865          * REPLACE query wrapper for MySQL and SQLite, which have a native REPLACE
2866          * statement.
2867          *
2868          * @param string $table Table name
2869          * @param array|string $rows Row(s) to insert
2870          * @param string $fname Caller function name
2871          */
2872         protected function nativeReplace( $table, $rows, $fname ) {
2873                 $table = $this->tableName( $table );
2874
2875                 # Single row case
2876                 if ( !is_array( reset( $rows ) ) ) {
2877                         $rows = [ $rows ];
2878                 }
2879
2880                 $sql = "REPLACE INTO $table (" . implode( ',', array_keys( $rows[0] ) ) . ') VALUES ';
2881                 $first = true;
2882
2883                 foreach ( $rows as $row ) {
2884                         if ( $first ) {
2885                                 $first = false;
2886                         } else {
2887                                 $sql .= ',';
2888                         }
2889
2890                         $sql .= '(' . $this->makeList( $row ) . ')';
2891                 }
2892
2893                 $this->query( $sql, $fname );
2894         }
2895
2896         public function upsert( $table, array $rows, $uniqueIndexes, array $set,
2897                 $fname = __METHOD__
2898         ) {
2899                 if ( $rows === [] ) {
2900                         return true; // nothing to do
2901                 }
2902
2903                 $uniqueIndexes = (array)$uniqueIndexes;
2904                 if ( !is_array( reset( $rows ) ) ) {
2905                         $rows = [ $rows ];
2906                 }
2907
2908                 if ( count( $uniqueIndexes ) ) {
2909                         $clauses = []; // list WHERE clauses that each identify a single row
2910                         foreach ( $rows as $row ) {
2911                                 foreach ( $uniqueIndexes as $index ) {
2912                                         $index = is_array( $index ) ? $index : [ $index ]; // columns
2913                                         $rowKey = []; // unique key to this row
2914                                         foreach ( $index as $column ) {
2915                                                 $rowKey[$column] = $row[$column];
2916                                         }
2917                                         $clauses[] = $this->makeList( $rowKey, self::LIST_AND );
2918                                 }
2919                         }
2920                         $where = [ $this->makeList( $clauses, self::LIST_OR ) ];
2921                 } else {
2922                         $where = false;
2923                 }
2924
2925                 $affectedRowCount = 0;
2926                 try {
2927                         $this->startAtomic( $fname, self::ATOMIC_CANCELABLE );
2928                         # Update any existing conflicting row(s)
2929                         if ( $where !== false ) {
2930                                 $this->update( $table, $set, $where, $fname );
2931                                 $affectedRowCount += $this->affectedRows();
2932                         }
2933                         # Now insert any non-conflicting row(s)
2934                         $this->insert( $table, $rows, $fname, [ 'IGNORE' ] );
2935                         $affectedRowCount += $this->affectedRows();
2936                         $this->endAtomic( $fname );
2937                         $this->affectedRowCount = $affectedRowCount;
2938                 } catch ( Exception $e ) {
2939                         $this->cancelAtomic( $fname );
2940                         throw $e;
2941                 }
2942
2943                 return true;
2944         }
2945
2946         public function deleteJoin( $delTable, $joinTable, $delVar, $joinVar, $conds,
2947                 $fname = __METHOD__
2948         ) {
2949                 if ( !$conds ) {
2950                         throw new DBUnexpectedError( $this, __METHOD__ . ' called with empty $conds' );
2951                 }
2952
2953                 $delTable = $this->tableName( $delTable );
2954                 $joinTable = $this->tableName( $joinTable );
2955                 $sql = "DELETE FROM $delTable WHERE $delVar IN (SELECT $joinVar FROM $joinTable ";
2956                 if ( $conds != '*' ) {
2957                         $sql .= 'WHERE ' . $this->makeList( $conds, self::LIST_AND );
2958                 }
2959                 $sql .= ')';
2960
2961                 $this->query( $sql, $fname );
2962         }
2963
2964         public function textFieldSize( $table, $field ) {
2965                 $table = $this->tableName( $table );
2966                 $sql = "SHOW COLUMNS FROM $table LIKE \"$field\";";
2967                 $res = $this->query( $sql, __METHOD__ );
2968                 $row = $this->fetchObject( $res );
2969
2970                 $m = [];
2971
2972                 if ( preg_match( '/\((.*)\)/', $row->Type, $m ) ) {
2973                         $size = $m[1];
2974                 } else {
2975                         $size = -1;
2976                 }
2977
2978                 return $size;
2979         }
2980
2981         public function delete( $table, $conds, $fname = __METHOD__ ) {
2982                 if ( !$conds ) {
2983                         throw new DBUnexpectedError( $this, __METHOD__ . ' called with no conditions' );
2984                 }
2985
2986                 $table = $this->tableName( $table );
2987                 $sql = "DELETE FROM $table";
2988
2989                 if ( $conds != '*' ) {
2990                         if ( is_array( $conds ) ) {
2991                                 $conds = $this->makeList( $conds, self::LIST_AND );
2992                         }
2993                         $sql .= ' WHERE ' . $conds;
2994                 }
2995
2996                 $this->query( $sql, $fname );
2997
2998                 return true;
2999         }
3000
3001         final public function insertSelect(
3002                 $destTable, $srcTable, $varMap, $conds,
3003                 $fname = __METHOD__, $insertOptions = [], $selectOptions = [], $selectJoinConds = []
3004         ) {
3005                 static $hints = [ 'NO_AUTO_COLUMNS' ];
3006
3007                 $insertOptions = (array)$insertOptions;
3008                 $selectOptions = (array)$selectOptions;
3009
3010                 if ( $this->cliMode && $this->isInsertSelectSafe( $insertOptions, $selectOptions ) ) {
3011                         // For massive migrations with downtime, we don't want to select everything
3012                         // into memory and OOM, so do all this native on the server side if possible.
3013                         $this->nativeInsertSelect(
3014                                 $destTable,
3015                                 $srcTable,
3016                                 $varMap,
3017                                 $conds,
3018                                 $fname,
3019                                 array_diff( $insertOptions, $hints ),
3020                                 $selectOptions,
3021                                 $selectJoinConds
3022                         );
3023                 } else {
3024                         $this->nonNativeInsertSelect(
3025                                 $destTable,
3026                                 $srcTable,
3027                                 $varMap,
3028                                 $conds,
3029                                 $fname,
3030                                 array_diff( $insertOptions, $hints ),
3031                                 $selectOptions,
3032                                 $selectJoinConds
3033                         );
3034                 }
3035
3036                 return true;
3037         }
3038
3039         /**
3040          * @param array $insertOptions INSERT options
3041          * @param array $selectOptions SELECT options
3042          * @return bool Whether an INSERT SELECT with these options will be replication safe
3043          * @since 1.31
3044          */
3045         protected function isInsertSelectSafe( array $insertOptions, array $selectOptions ) {
3046                 return true;
3047         }
3048
3049         /**
3050          * Implementation of insertSelect() based on select() and insert()
3051          *
3052          * @see IDatabase::insertSelect()
3053          * @since 1.30
3054          * @param string $destTable
3055          * @param string|array $srcTable
3056          * @param array $varMap
3057          * @param array $conds
3058          * @param string $fname
3059          * @param array $insertOptions
3060          * @param array $selectOptions
3061          * @param array $selectJoinConds
3062          */
3063         protected function nonNativeInsertSelect( $destTable, $srcTable, $varMap, $conds,
3064                 $fname = __METHOD__,
3065                 $insertOptions = [], $selectOptions = [], $selectJoinConds = []
3066         ) {
3067                 // For web requests, do a locking SELECT and then INSERT. This puts the SELECT burden
3068                 // on only the master (without needing row-based-replication). It also makes it easy to
3069                 // know how big the INSERT is going to be.
3070                 $fields = [];
3071                 foreach ( $varMap as $dstColumn => $sourceColumnOrSql ) {
3072                         $fields[] = $this->fieldNameWithAlias( $sourceColumnOrSql, $dstColumn );
3073                 }
3074                 $selectOptions[] = 'FOR UPDATE';
3075                 $res = $this->select(
3076                         $srcTable, implode( ',', $fields ), $conds, $fname, $selectOptions, $selectJoinConds
3077                 );
3078                 if ( !$res ) {
3079                         return;
3080                 }
3081
3082                 try {
3083                         $affectedRowCount = 0;
3084                         $this->startAtomic( $fname, self::ATOMIC_CANCELABLE );
3085                         $rows = [];
3086                         $ok = true;
3087                         foreach ( $res as $row ) {
3088                                 $rows[] = (array)$row;
3089
3090                                 // Avoid inserts that are too huge
3091                                 if ( count( $rows ) >= $this->nonNativeInsertSelectBatchSize ) {
3092                                         $ok = $this->insert( $destTable, $rows, $fname, $insertOptions );
3093                                         if ( !$ok ) {
3094                                                 break;
3095                                         }
3096                                         $affectedRowCount += $this->affectedRows();
3097                                         $rows = [];
3098                                 }
3099                         }
3100                         if ( $rows && $ok ) {
3101                                 $ok = $this->insert( $destTable, $rows, $fname, $insertOptions );
3102                                 if ( $ok ) {
3103                                         $affectedRowCount += $this->affectedRows();
3104                                 }
3105                         }
3106                         if ( $ok ) {
3107                                 $this->endAtomic( $fname );
3108                                 $this->affectedRowCount = $affectedRowCount;
3109                         } else {
3110                                 $this->cancelAtomic( $fname );
3111                         }
3112                 } catch ( Exception $e ) {
3113                         $this->cancelAtomic( $fname );
3114                         throw $e;
3115                 }
3116         }
3117
3118         /**
3119          * Native server-side implementation of insertSelect() for situations where
3120          * we don't want to select everything into memory
3121          *
3122          * @see IDatabase::insertSelect()
3123          * @param string $destTable
3124          * @param string|array $srcTable
3125          * @param array $varMap
3126          * @param array $conds
3127          * @param string $fname
3128          * @param array $insertOptions
3129          * @param array $selectOptions
3130          * @param array $selectJoinConds
3131          */
3132         protected function nativeInsertSelect( $destTable, $srcTable, $varMap, $conds,
3133                 $fname = __METHOD__,
3134                 $insertOptions = [], $selectOptions = [], $selectJoinConds = []
3135         ) {
3136                 $destTable = $this->tableName( $destTable );
3137
3138                 if ( !is_array( $insertOptions ) ) {
3139                         $insertOptions = [ $insertOptions ];
3140                 }
3141
3142                 $insertOptions = $this->makeInsertOptions( $insertOptions );
3143
3144                 $selectSql = $this->selectSQLText(
3145                         $srcTable,
3146                         array_values( $varMap ),
3147                         $conds,
3148                         $fname,
3149                         $selectOptions,
3150                         $selectJoinConds
3151                 );
3152
3153                 $sql = "INSERT $insertOptions" .
3154                         " INTO $destTable (" . implode( ',', array_keys( $varMap ) ) . ') ' .
3155                         $selectSql;
3156
3157                 $this->query( $sql, $fname );
3158         }
3159
3160         /**
3161          * Construct a LIMIT query with optional offset. This is used for query
3162          * pages. The SQL should be adjusted so that only the first $limit rows
3163          * are returned. If $offset is provided as well, then the first $offset
3164          * rows should be discarded, and the next $limit rows should be returned.
3165          * If the result of the query is not ordered, then the rows to be returned
3166          * are theoretically arbitrary.
3167          *
3168          * $sql is expected to be a SELECT, if that makes a difference.
3169          *
3170          * The version provided by default works in MySQL and SQLite. It will very
3171          * likely need to be overridden for most other DBMSes.
3172          *
3173          * @param string $sql SQL query we will append the limit too
3174          * @param int $limit The SQL limit
3175          * @param int|bool $offset The SQL offset (default false)
3176          * @throws DBUnexpectedError
3177          * @return string
3178          */
3179         public function limitResult( $sql, $limit, $offset = false ) {
3180                 if ( !is_numeric( $limit ) ) {
3181                         throw new DBUnexpectedError( $this,
3182                                 "Invalid non-numeric limit passed to limitResult()\n" );
3183                 }
3184
3185                 return "$sql LIMIT "
3186                 . ( ( is_numeric( $offset ) && $offset != 0 ) ? "{$offset}," : "" )
3187                 . "{$limit} ";
3188         }
3189
3190         public function unionSupportsOrderAndLimit() {
3191                 return true; // True for almost every DB supported
3192         }
3193
3194         public function unionQueries( $sqls, $all ) {
3195                 $glue = $all ? ') UNION ALL (' : ') UNION (';
3196
3197                 return '(' . implode( $glue, $sqls ) . ')';
3198         }
3199
3200         public function unionConditionPermutations(
3201                 $table, $vars, array $permute_conds, $extra_conds = '', $fname = __METHOD__,
3202                 $options = [], $join_conds = []
3203         ) {
3204                 // First, build the Cartesian product of $permute_conds
3205                 $conds = [ [] ];
3206                 foreach ( $permute_conds as $field => $values ) {
3207                         if ( !$values ) {
3208                                 // Skip empty $values
3209                                 continue;
3210                         }
3211                         $values = array_unique( $values ); // For sanity
3212                         $newConds = [];
3213                         foreach ( $conds as $cond ) {
3214                                 foreach ( $values as $value ) {
3215                                         $cond[$field] = $value;
3216                                         $newConds[] = $cond; // Arrays are by-value, not by-reference, so this works
3217                                 }
3218                         }
3219                         $conds = $newConds;
3220                 }
3221
3222                 $extra_conds = $extra_conds === '' ? [] : (array)$extra_conds;
3223
3224                 // If there's just one condition and no subordering, hand off to
3225                 // selectSQLText directly.
3226                 if ( count( $conds ) === 1 &&
3227                         ( !isset( $options['INNER ORDER BY'] ) || !$this->unionSupportsOrderAndLimit() )
3228                 ) {
3229                         return $this->selectSQLText(
3230                                 $table, $vars, $conds[0] + $extra_conds, $fname, $options, $join_conds
3231                         );
3232                 }
3233
3234                 // Otherwise, we need to pull out the order and limit to apply after
3235                 // the union. Then build the SQL queries for each set of conditions in
3236                 // $conds. Then union them together (using UNION ALL, because the
3237                 // product *should* already be distinct).
3238                 $orderBy = $this->makeOrderBy( $options );
3239                 $limit = $options['LIMIT'] ?? null;
3240                 $offset = $options['OFFSET'] ?? false;
3241                 $all = empty( $options['NOTALL'] ) && !in_array( 'NOTALL', $options );
3242                 if ( !$this->unionSupportsOrderAndLimit() ) {
3243                         unset( $options['ORDER BY'], $options['LIMIT'], $options['OFFSET'] );
3244                 } else {
3245                         if ( array_key_exists( 'INNER ORDER BY', $options ) ) {
3246                                 $options['ORDER BY'] = $options['INNER ORDER BY'];
3247                         }
3248                         if ( $limit !== null && is_numeric( $offset ) && $offset != 0 ) {
3249                                 // We need to increase the limit by the offset rather than
3250                                 // using the offset directly, otherwise it'll skip incorrectly
3251                                 // in the subqueries.
3252                                 $options['LIMIT'] = $limit + $offset;
3253                                 unset( $options['OFFSET'] );
3254                         }
3255                 }
3256
3257                 $sqls = [];
3258                 foreach ( $conds as $cond ) {
3259                         $sqls[] = $this->selectSQLText(
3260                                 $table, $vars, $cond + $extra_conds, $fname, $options, $join_conds
3261                         );
3262                 }
3263                 $sql = $this->unionQueries( $sqls, $all ) . $orderBy;
3264                 if ( $limit !== null ) {
3265                         $sql = $this->limitResult( $sql, $limit, $offset );
3266                 }
3267
3268                 return $sql;
3269         }
3270
3271         public function conditional( $cond, $trueVal, $falseVal ) {
3272                 if ( is_array( $cond ) ) {
3273                         $cond = $this->makeList( $cond, self::LIST_AND );
3274                 }
3275
3276                 return " (CASE WHEN $cond THEN $trueVal ELSE $falseVal END) ";
3277         }
3278
3279         public function strreplace( $orig, $old, $new ) {
3280                 return "REPLACE({$orig}, {$old}, {$new})";
3281         }
3282
3283         public function getServerUptime() {
3284                 return 0;
3285         }
3286
3287         public function wasDeadlock() {
3288                 return false;
3289         }
3290
3291         public function wasLockTimeout() {
3292                 return false;
3293         }
3294
3295         public function wasConnectionLoss() {
3296                 return $this->wasConnectionError( $this->lastErrno() );
3297         }
3298
3299         public function wasReadOnlyError() {
3300                 return false;
3301         }
3302
3303         public function wasErrorReissuable() {
3304                 return (
3305                         $this->wasDeadlock() ||
3306                         $this->wasLockTimeout() ||
3307                         $this->wasConnectionLoss()
3308                 );
3309         }
3310
3311         /**
3312          * Do not use this method outside of Database/DBError classes
3313          *
3314          * @param int|string $errno
3315          * @return bool Whether the given query error was a connection drop
3316          */
3317         public function wasConnectionError( $errno ) {
3318                 return false;
3319         }
3320
3321         /**
3322          * @return bool Whether it is known that the last query error only caused statement rollback
3323          * @note This is for backwards compatibility for callers catching DBError exceptions in
3324          *   order to ignore problems like duplicate key errors or foriegn key violations
3325          * @since 1.31
3326          */
3327         protected function wasKnownStatementRollbackError() {
3328                 return false; // don't know; it could have caused a transaction rollback
3329         }
3330
3331         public function deadlockLoop() {
3332                 $args = func_get_args();
3333                 $function = array_shift( $args );
3334                 $tries = self::DEADLOCK_TRIES;
3335
3336                 $this->begin( __METHOD__ );
3337
3338                 $retVal = null;
3339                 /** @var Exception $e */
3340                 $e = null;
3341                 do {
3342                         try {
3343                                 $retVal = $function( ...$args );
3344                                 break;
3345                         } catch ( DBQueryError $e ) {
3346                                 if ( $this->wasDeadlock() ) {
3347                                         // Retry after a randomized delay
3348                                         usleep( mt_rand( self::DEADLOCK_DELAY_MIN, self::DEADLOCK_DELAY_MAX ) );
3349                                 } else {
3350                                         // Throw the error back up
3351                                         throw $e;
3352                                 }
3353                         }
3354                 } while ( --$tries > 0 );
3355
3356                 if ( $tries <= 0 ) {
3357                         // Too many deadlocks; give up
3358                         $this->rollback( __METHOD__ );
3359                         throw $e;
3360                 } else {
3361                         $this->commit( __METHOD__ );
3362
3363                         return $retVal;
3364                 }
3365         }
3366
3367         public function masterPosWait( DBMasterPos $pos, $timeout ) {
3368                 # Real waits are implemented in the subclass.
3369                 return 0;
3370         }
3371
3372         public function getReplicaPos() {
3373                 # Stub
3374                 return false;
3375         }
3376
3377         public function getMasterPos() {
3378                 # Stub
3379                 return false;
3380         }
3381
3382         public function serverIsReadOnly() {
3383                 return false;
3384         }
3385
3386         final public function onTransactionResolution( callable $callback, $fname = __METHOD__ ) {
3387                 if ( !$this->trxLevel ) {
3388                         throw new DBUnexpectedError( $this, "No transaction is active." );
3389                 }
3390                 $this->trxEndCallbacks[] = [ $callback, $fname, $this->currentAtomicSectionId() ];
3391         }
3392
3393         final public function onTransactionCommitOrIdle( callable $callback, $fname = __METHOD__ ) {
3394                 if ( !$this->trxLevel && $this->getTransactionRoundId() ) {
3395                         // Start an implicit transaction similar to how query() does
3396                         $this->begin( __METHOD__, self::TRANSACTION_INTERNAL );
3397                         $this->trxAutomatic = true;
3398                 }
3399
3400                 $this->trxIdleCallbacks[] = [ $callback, $fname, $this->currentAtomicSectionId() ];
3401                 if ( !$this->trxLevel ) {
3402                         $this->runOnTransactionIdleCallbacks( self::TRIGGER_IDLE );
3403                 }
3404         }
3405
3406         final public function onTransactionIdle( callable $callback, $fname = __METHOD__ ) {
3407                 $this->onTransactionCommitOrIdle( $callback, $fname );
3408         }
3409
3410         final public function onTransactionPreCommitOrIdle( callable $callback, $fname = __METHOD__ ) {
3411                 if ( !$this->trxLevel && $this->getTransactionRoundId() ) {
3412                         // Start an implicit transaction similar to how query() does
3413                         $this->begin( __METHOD__, self::TRANSACTION_INTERNAL );
3414                         $this->trxAutomatic = true;
3415                 }
3416
3417                 if ( $this->trxLevel ) {
3418                         $this->trxPreCommitCallbacks[] = [ $callback, $fname, $this->currentAtomicSectionId() ];
3419                 } else {
3420                         // No transaction is active nor will start implicitly, so make one for this callback
3421                         $this->startAtomic( __METHOD__, self::ATOMIC_CANCELABLE );
3422                         try {
3423                                 $callback( $this );
3424                                 $this->endAtomic( __METHOD__ );
3425                         } catch ( Exception $e ) {
3426                                 $this->cancelAtomic( __METHOD__ );
3427                                 throw $e;
3428                         }
3429                 }
3430         }
3431
3432         /**
3433          * @return AtomicSectionIdentifier|null ID of the topmost atomic section level
3434          */
3435         private function currentAtomicSectionId() {
3436                 if ( $this->trxLevel && $this->trxAtomicLevels ) {
3437                         $levelInfo = end( $this->trxAtomicLevels );
3438
3439                         return $levelInfo[1];
3440                 }
3441
3442                 return null;
3443         }
3444
3445         /**
3446          * @param AtomicSectionIdentifier $old
3447          * @param AtomicSectionIdentifier $new
3448          */
3449         private function reassignCallbacksForSection(
3450                 AtomicSectionIdentifier $old, AtomicSectionIdentifier $new
3451         ) {
3452                 foreach ( $this->trxPreCommitCallbacks as $key => $info ) {
3453                         if ( $info[2] === $old ) {
3454                                 $this->trxPreCommitCallbacks[$key][2] = $new;
3455                         }
3456                 }
3457                 foreach ( $this->trxIdleCallbacks as $key => $info ) {
3458                         if ( $info[2] === $old ) {
3459                                 $this->trxIdleCallbacks[$key][2] = $new;
3460                         }
3461                 }
3462                 foreach ( $this->trxEndCallbacks as $key => $info ) {
3463                         if ( $info[2] === $old ) {
3464                                 $this->trxEndCallbacks[$key][2] = $new;
3465                         }
3466                 }
3467         }
3468
3469         /**
3470          * @param AtomicSectionIdentifier[] $sectionIds ID of an actual savepoint
3471          * @throws UnexpectedValueException
3472          */
3473         private function modifyCallbacksForCancel( array $sectionIds ) {
3474                 // Cancel the "on commit" callbacks owned by this savepoint
3475                 $this->trxIdleCallbacks = array_filter(
3476                         $this->trxIdleCallbacks,
3477                         function ( $entry ) use ( $sectionIds ) {
3478                                 return !in_array( $entry[2], $sectionIds, true );
3479                         }
3480                 );
3481                 $this->trxPreCommitCallbacks = array_filter(
3482                         $this->trxPreCommitCallbacks,
3483                         function ( $entry ) use ( $sectionIds ) {
3484                                 return !in_array( $entry[2], $sectionIds, true );
3485                         }
3486                 );
3487                 // Make "on resolution" callbacks owned by this savepoint to perceive a rollback
3488                 foreach ( $this->trxEndCallbacks as $key => $entry ) {
3489                         if ( in_array( $entry[2], $sectionIds, true ) ) {
3490                                 $callback = $entry[0];
3491                                 $this->trxEndCallbacks[$key][0] = function () use ( $callback ) {
3492                                         return $callback( self::TRIGGER_ROLLBACK, $this );
3493                                 };
3494                         }
3495                 }
3496         }
3497
3498         final public function setTransactionListener( $name, callable $callback = null ) {
3499                 if ( $callback ) {
3500                         $this->trxRecurringCallbacks[$name] = $callback;
3501                 } else {
3502                         unset( $this->trxRecurringCallbacks[$name] );
3503                 }
3504         }
3505
3506         /**
3507          * Whether to disable running of post-COMMIT/ROLLBACK callbacks
3508          *
3509          * This method should not be used outside of Database/LoadBalancer
3510          *
3511          * @param bool $suppress
3512          * @since 1.28
3513          */
3514         final public function setTrxEndCallbackSuppression( $suppress ) {
3515                 $this->trxEndCallbacksSuppressed = $suppress;
3516         }
3517
3518         /**
3519          * Actually consume and run any "on transaction idle/resolution" callbacks.
3520          *
3521          * This method should not be used outside of Database/LoadBalancer
3522          *
3523          * @param int $trigger IDatabase::TRIGGER_* constant
3524          * @return int Number of callbacks attempted
3525          * @since 1.20
3526          * @throws Exception
3527          */
3528         public function runOnTransactionIdleCallbacks( $trigger ) {
3529                 if ( $this->trxLevel ) { // sanity
3530                         throw new DBUnexpectedError( $this, __METHOD__ . ': a transaction is still open.' );
3531                 }
3532
3533                 if ( $this->trxEndCallbacksSuppressed ) {
3534                         return 0;
3535                 }
3536
3537                 $count = 0;
3538                 $autoTrx = $this->getFlag( self::DBO_TRX ); // automatic begin() enabled?
3539                 /** @var Exception $e */
3540                 $e = null; // first exception
3541                 do { // callbacks may add callbacks :)
3542                         $callbacks = array_merge(
3543                                 $this->trxIdleCallbacks,
3544                                 $this->trxEndCallbacks // include "transaction resolution" callbacks
3545                         );
3546                         $this->trxIdleCallbacks = []; // consumed (and recursion guard)
3547                         $this->trxEndCallbacks = []; // consumed (recursion guard)
3548                         foreach ( $callbacks as $callback ) {
3549                                 ++$count;
3550                                 list( $phpCallback ) = $callback;
3551                                 $this->clearFlag( self::DBO_TRX ); // make each query its own transaction
3552                                 try {
3553                                         call_user_func( $phpCallback, $trigger, $this );
3554                                 } catch ( Exception $ex ) {
3555                                         call_user_func( $this->errorLogger, $ex );
3556                                         $e = $e ?: $ex;
3557                                         // Some callbacks may use startAtomic/endAtomic, so make sure
3558                                         // their transactions are ended so other callbacks don't fail
3559                                         if ( $this->trxLevel() ) {
3560                                                 $this->rollback( __METHOD__, self::FLUSHING_INTERNAL );
3561                                         }
3562                                 } finally {
3563                                         if ( $autoTrx ) {
3564                                                 $this->setFlag( self::DBO_TRX ); // restore automatic begin()
3565                                         } else {
3566                                                 $this->clearFlag( self::DBO_TRX ); // restore auto-commit
3567                                         }
3568                                 }
3569                         }
3570                 } while ( count( $this->trxIdleCallbacks ) );
3571
3572                 if ( $e instanceof Exception ) {
3573                         throw $e; // re-throw any first exception
3574                 }
3575
3576                 return $count;
3577         }
3578
3579         /**
3580          * Actually consume and run any "on transaction pre-commit" callbacks.
3581          *
3582          * This method should not be used outside of Database/LoadBalancer
3583          *
3584          * @since 1.22
3585          * @return int Number of callbacks attempted
3586          * @throws Exception
3587          */
3588         public function runOnTransactionPreCommitCallbacks() {
3589                 $count = 0;
3590
3591                 $e = null; // first exception
3592                 do { // callbacks may add callbacks :)
3593                         $callbacks = $this->trxPreCommitCallbacks;
3594                         $this->trxPreCommitCallbacks = []; // consumed (and recursion guard)
3595                         foreach ( $callbacks as $callback ) {
3596                                 try {
3597                                         ++$count;
3598                                         list( $phpCallback ) = $callback;
3599                                         $phpCallback( $this );
3600                                 } catch ( Exception $ex ) {
3601                                         ( $this->errorLogger )( $ex );
3602                                         $e = $e ?: $ex;
3603                                 }
3604                         }
3605                 } while ( count( $this->trxPreCommitCallbacks ) );
3606
3607                 if ( $e instanceof Exception ) {
3608                         throw $e; // re-throw any first exception
3609                 }
3610
3611                 return $count;
3612         }
3613
3614         /**
3615          * Actually run any "transaction listener" callbacks.
3616          *
3617          * This method should not be used outside of Database/LoadBalancer
3618          *
3619          * @param int $trigger IDatabase::TRIGGER_* constant
3620          * @throws Exception
3621          * @since 1.20
3622          */
3623         public function runTransactionListenerCallbacks( $trigger ) {
3624                 if ( $this->trxEndCallbacksSuppressed ) {
3625                         return;
3626                 }
3627
3628                 /** @var Exception $e */
3629                 $e = null; // first exception
3630
3631                 foreach ( $this->trxRecurringCallbacks as $phpCallback ) {
3632                         try {
3633                                 $phpCallback( $trigger, $this );
3634                         } catch ( Exception $ex ) {
3635                                 ( $this->errorLogger )( $ex );
3636                                 $e = $e ?: $ex;
3637                         }
3638                 }
3639
3640                 if ( $e instanceof Exception ) {
3641                         throw $e; // re-throw any first exception
3642                 }
3643         }
3644
3645         /**
3646          * Create a savepoint
3647          *
3648          * This is used internally to implement atomic sections. It should not be
3649          * used otherwise.
3650          *
3651          * @since 1.31
3652          * @param string $identifier Identifier for the savepoint
3653          * @param string $fname Calling function name
3654          */
3655         protected function doSavepoint( $identifier, $fname ) {
3656                 $this->query( 'SAVEPOINT ' . $this->addIdentifierQuotes( $identifier ), $fname );
3657         }
3658
3659         /**
3660          * Release a savepoint
3661          *
3662          * This is used internally to implement atomic sections. It should not be
3663          * used otherwise.
3664          *
3665          * @since 1.31
3666          * @param string $identifier Identifier for the savepoint
3667          * @param string $fname Calling function name
3668          */
3669         protected function doReleaseSavepoint( $identifier, $fname ) {
3670                 $this->query( 'RELEASE SAVEPOINT ' . $this->addIdentifierQuotes( $identifier ), $fname );
3671         }
3672
3673         /**
3674          * Rollback to a savepoint
3675          *
3676          * This is used internally to implement atomic sections. It should not be
3677          * used otherwise.
3678          *
3679          * @since 1.31
3680          * @param string $identifier Identifier for the savepoint
3681          * @param string $fname Calling function name
3682          */
3683         protected function doRollbackToSavepoint( $identifier, $fname ) {
3684                 $this->query( 'ROLLBACK TO SAVEPOINT ' . $this->addIdentifierQuotes( $identifier ), $fname );
3685         }
3686
3687         /**
3688          * @param string $fname
3689          * @return string
3690          */
3691         private function nextSavepointId( $fname ) {
3692                 $savepointId = self::$SAVEPOINT_PREFIX . ++$this->trxAtomicCounter;
3693                 if ( strlen( $savepointId ) > 30 ) {
3694                         // 30 == Oracle's identifier length limit (pre 12c)
3695                         // With a 22 character prefix, that puts the highest number at 99999999.
3696                         throw new DBUnexpectedError(
3697                                 $this,
3698                                 'There have been an excessively large number of atomic sections in a transaction'
3699                                 . " started by $this->trxFname (at $fname)"
3700                         );
3701                 }
3702
3703                 return $savepointId;
3704         }
3705
3706         final public function startAtomic(
3707                 $fname = __METHOD__, $cancelable = self::ATOMIC_NOT_CANCELABLE
3708         ) {
3709                 $savepointId = $cancelable === self::ATOMIC_CANCELABLE ? self::$NOT_APPLICABLE : null;
3710
3711                 if ( !$this->trxLevel ) {
3712                         $this->begin( $fname, self::TRANSACTION_INTERNAL ); // sets trxAutomatic
3713                         // If DBO_TRX is set, a series of startAtomic/endAtomic pairs will result
3714                         // in all changes being in one transaction to keep requests transactional.
3715                         if ( $this->getFlag( self::DBO_TRX ) ) {
3716                                 // Since writes could happen in between the topmost atomic sections as part
3717                                 // of the transaction, those sections will need savepoints.
3718                                 $savepointId = $this->nextSavepointId( $fname );
3719                                 $this->doSavepoint( $savepointId, $fname );
3720                         } else {
3721                                 $this->trxAutomaticAtomic = true;
3722                         }
3723                 } elseif ( $cancelable === self::ATOMIC_CANCELABLE ) {
3724                         $savepointId = $this->nextSavepointId( $fname );
3725                         $this->doSavepoint( $savepointId, $fname );
3726                 }
3727
3728                 $sectionId = new AtomicSectionIdentifier;
3729                 $this->trxAtomicLevels[] = [ $fname, $sectionId, $savepointId ];
3730                 $this->queryLogger->debug( 'startAtomic: entering level ' .
3731                         ( count( $this->trxAtomicLevels ) - 1 ) . " ($fname)" );
3732
3733                 return $sectionId;
3734         }
3735
3736         final public function endAtomic( $fname = __METHOD__ ) {
3737                 if ( !$this->trxLevel || !$this->trxAtomicLevels ) {
3738                         throw new DBUnexpectedError( $this, "No atomic section is open (got $fname)." );
3739                 }
3740
3741                 // Check if the current section matches $fname
3742                 $pos = count( $this->trxAtomicLevels ) - 1;
3743                 list( $savedFname, $sectionId, $savepointId ) = $this->trxAtomicLevels[$pos];
3744                 $this->queryLogger->debug( "endAtomic: leaving level $pos ($fname)" );
3745
3746                 if ( $savedFname !== $fname ) {
3747                         throw new DBUnexpectedError(
3748                                 $this,
3749                                 "Invalid atomic section ended (got $fname but expected $savedFname)."
3750                         );
3751                 }
3752
3753                 // Remove the last section (no need to re-index the array)
3754                 array_pop( $this->trxAtomicLevels );
3755
3756                 if ( !$this->trxAtomicLevels && $this->trxAutomaticAtomic ) {
3757                         $this->commit( $fname, self::FLUSHING_INTERNAL );
3758                 } elseif ( $savepointId !== null && $savepointId !== self::$NOT_APPLICABLE ) {
3759                         $this->doReleaseSavepoint( $savepointId, $fname );
3760                 }
3761
3762                 // Hoist callback ownership for callbacks in the section that just ended;
3763                 // all callbacks should have an owner that is present in trxAtomicLevels.
3764                 $currentSectionId = $this->currentAtomicSectionId();
3765                 if ( $currentSectionId ) {
3766                         $this->reassignCallbacksForSection( $sectionId, $currentSectionId );
3767                 }
3768         }
3769
3770         final public function cancelAtomic(
3771                 $fname = __METHOD__, AtomicSectionIdentifier $sectionId = null
3772         ) {
3773                 if ( !$this->trxLevel || !$this->trxAtomicLevels ) {
3774                         throw new DBUnexpectedError( $this, "No atomic section is open (got $fname)." );
3775                 }
3776
3777                 $excisedFnames = [];
3778                 if ( $sectionId !== null ) {
3779                         // Find the (last) section with the given $sectionId
3780                         $pos = -1;
3781                         foreach ( $this->trxAtomicLevels as $i => list( $asFname, $asId, $spId ) ) {
3782                                 if ( $asId === $sectionId ) {
3783                                         $pos = $i;
3784                                 }
3785                         }
3786                         if ( $pos < 0 ) {
3787                                 throw new DBUnexpectedError( $this, "Atomic section not found (for $fname)" );
3788                         }
3789                         // Remove all descendant sections and re-index the array
3790                         $excisedIds = [];
3791                         $len = count( $this->trxAtomicLevels );
3792                         for ( $i = $pos + 1; $i < $len; ++$i ) {
3793                                 $excisedFnames[] = $this->trxAtomicLevels[$i][0];
3794                                 $excisedIds[] = $this->trxAtomicLevels[$i][1];
3795                         }
3796                         $this->trxAtomicLevels = array_slice( $this->trxAtomicLevels, 0, $pos + 1 );
3797                         $this->modifyCallbacksForCancel( $excisedIds );
3798                 }
3799
3800                 // Check if the current section matches $fname
3801                 $pos = count( $this->trxAtomicLevels ) - 1;
3802                 list( $savedFname, $savedSectionId, $savepointId ) = $this->trxAtomicLevels[$pos];
3803
3804                 if ( $excisedFnames ) {
3805                         $this->queryLogger->debug( "cancelAtomic: canceling level $pos ($savedFname) " .
3806                                 "and descendants " . implode( ', ', $excisedFnames ) );
3807                 } else {
3808                         $this->queryLogger->debug( "cancelAtomic: canceling level $pos ($savedFname)" );
3809                 }
3810
3811                 if ( $savedFname !== $fname ) {
3812                         throw new DBUnexpectedError(
3813                                 $this,
3814                                 "Invalid atomic section ended (got $fname but expected $savedFname)."
3815                         );
3816                 }
3817
3818                 // Remove the last section (no need to re-index the array)
3819                 array_pop( $this->trxAtomicLevels );
3820                 $this->modifyCallbacksForCancel( [ $savedSectionId ] );
3821
3822                 if ( $savepointId !== null ) {
3823                         // Rollback the transaction to the state just before this atomic section
3824                         if ( $savepointId === self::$NOT_APPLICABLE ) {
3825                                 $this->rollback( $fname, self::FLUSHING_INTERNAL );
3826                         } else {
3827                                 $this->doRollbackToSavepoint( $savepointId, $fname );
3828                                 $this->trxStatus = self::STATUS_TRX_OK; // no exception; recovered
3829                                 $this->trxStatusIgnoredCause = null;
3830                         }
3831                 } elseif ( $this->trxStatus > self::STATUS_TRX_ERROR ) {
3832                         // Put the transaction into an error state if it's not already in one
3833                         $this->trxStatus = self::STATUS_TRX_ERROR;
3834                         $this->trxStatusCause = new DBUnexpectedError(
3835                                 $this,
3836                                 "Uncancelable atomic section canceled (got $fname)."
3837                         );
3838                 }
3839
3840                 $this->affectedRowCount = 0; // for the sake of consistency
3841         }
3842
3843         final public function doAtomicSection(
3844                 $fname, callable $callback, $cancelable = self::ATOMIC_NOT_CANCELABLE
3845         ) {
3846                 $sectionId = $this->startAtomic( $fname, $cancelable );
3847                 try {
3848                         $res = $callback( $this, $fname );
3849                 } catch ( Exception $e ) {
3850                         $this->cancelAtomic( $fname, $sectionId );
3851
3852                         throw $e;
3853                 }
3854                 $this->endAtomic( $fname );
3855
3856                 return $res;
3857         }
3858
3859         final public function begin( $fname = __METHOD__, $mode = self::TRANSACTION_EXPLICIT ) {
3860                 static $modes = [ self::TRANSACTION_EXPLICIT, self::TRANSACTION_INTERNAL ];
3861                 if ( !in_array( $mode, $modes, true ) ) {
3862                         throw new DBUnexpectedError( $this, "$fname: invalid mode parameter '$mode'." );
3863                 }
3864
3865                 // Protect against mismatched atomic section, transaction nesting, and snapshot loss
3866                 if ( $this->trxLevel ) {
3867                         if ( $this->trxAtomicLevels ) {
3868                                 $levels = $this->flatAtomicSectionList();
3869                                 $msg = "$fname: Got explicit BEGIN while atomic section(s) $levels are open.";
3870                                 throw new DBUnexpectedError( $this, $msg );
3871                         } elseif ( !$this->trxAutomatic ) {
3872                                 $msg = "$fname: Explicit transaction already active (from {$this->trxFname}).";
3873                                 throw new DBUnexpectedError( $this, $msg );
3874                         } else {
3875                                 $msg = "$fname: Implicit transaction already active (from {$this->trxFname}).";
3876                                 throw new DBUnexpectedError( $this, $msg );
3877                         }
3878                 } elseif ( $this->getFlag( self::DBO_TRX ) && $mode !== self::TRANSACTION_INTERNAL ) {
3879                         $msg = "$fname: Implicit transaction expected (DBO_TRX set).";
3880                         throw new DBUnexpectedError( $this, $msg );
3881                 }
3882
3883                 $this->assertHasConnectionHandle();
3884
3885                 $this->doBegin( $fname );
3886                 $this->trxStatus = self::STATUS_TRX_OK;
3887                 $this->trxStatusIgnoredCause = null;
3888                 $this->trxAtomicCounter = 0;
3889                 $this->trxTimestamp = microtime( true );
3890                 $this->trxFname = $fname;
3891                 $this->trxDoneWrites = false;
3892                 $this->trxAutomaticAtomic = false;
3893                 $this->trxAtomicLevels = [];
3894                 $this->trxShortId = sprintf( '%06x', mt_rand( 0, 0xffffff ) );
3895                 $this->trxWriteDuration = 0.0;
3896                 $this->trxWriteQueryCount = 0;
3897                 $this->trxWriteAffectedRows = 0;
3898                 $this->trxWriteAdjDuration = 0.0;
3899                 $this->trxWriteAdjQueryCount = 0;
3900                 $this->trxWriteCallers = [];
3901                 // First SELECT after BEGIN will establish the snapshot in REPEATABLE-READ.
3902                 // Get an estimate of the replication lag before any such queries.
3903                 $this->trxReplicaLag = null; // clear cached value first
3904                 $this->trxReplicaLag = $this->getApproximateLagStatus()['lag'];
3905                 // T147697: make explicitTrxActive() return true until begin() finishes. This way, no
3906                 // caller will think its OK to muck around with the transaction just because startAtomic()
3907                 // has not yet completed (e.g. setting trxAtomicLevels).
3908                 $this->trxAutomatic = ( $mode === self::TRANSACTION_INTERNAL );
3909         }
3910
3911         /**
3912          * Issues the BEGIN command to the database server.
3913          *
3914          * @see Database::begin()
3915          * @param string $fname
3916          */
3917         protected function doBegin( $fname ) {
3918                 $this->query( 'BEGIN', $fname );
3919                 $this->trxLevel = 1;
3920         }
3921
3922         final public function commit( $fname = __METHOD__, $flush = self::FLUSHING_ONE ) {
3923                 static $modes = [ self::FLUSHING_ONE, self::FLUSHING_ALL_PEERS, self::FLUSHING_INTERNAL ];
3924                 if ( !in_array( $flush, $modes, true ) ) {
3925                         throw new DBUnexpectedError( $this, "$fname: invalid flush parameter '$flush'." );
3926                 }
3927
3928                 if ( $this->trxLevel && $this->trxAtomicLevels ) {
3929                         // There are still atomic sections open; this cannot be ignored
3930                         $levels = $this->flatAtomicSectionList();
3931                         throw new DBUnexpectedError(
3932                                 $this,
3933                                 "$fname: Got COMMIT while atomic sections $levels are still open."
3934                         );
3935                 }
3936
3937                 if ( $flush === self::FLUSHING_INTERNAL || $flush === self::FLUSHING_ALL_PEERS ) {
3938                         if ( !$this->trxLevel ) {
3939                                 return; // nothing to do
3940                         } elseif ( !$this->trxAutomatic ) {
3941                                 throw new DBUnexpectedError(
3942                                         $this,
3943                                         "$fname: Flushing an explicit transaction, getting out of sync."
3944                                 );
3945                         }
3946                 } else {
3947                         if ( !$this->trxLevel ) {
3948                                 $this->queryLogger->error(
3949                                         "$fname: No transaction to commit, something got out of sync." );
3950                                 return; // nothing to do
3951                         } elseif ( $this->trxAutomatic ) {
3952                                 throw new DBUnexpectedError(
3953                                         $this,
3954                                         "$fname: Expected mass commit of all peer transactions (DBO_TRX set)."
3955                                 );
3956                         }
3957                 }
3958
3959                 $this->assertHasConnectionHandle();
3960
3961                 $this->runOnTransactionPreCommitCallbacks();
3962
3963                 $writeTime = $this->pendingWriteQueryDuration( self::ESTIMATE_DB_APPLY );
3964                 $this->doCommit( $fname );
3965                 $this->trxStatus = self::STATUS_TRX_NONE;
3966
3967                 if ( $this->trxDoneWrites ) {
3968                         $this->lastWriteTime = microtime( true );
3969                         $this->trxProfiler->transactionWritingOut(
3970                                 $this->server,
3971                                 $this->getDomainID(),
3972                                 $this->trxShortId,
3973                                 $writeTime,
3974                                 $this->trxWriteAffectedRows
3975                         );
3976                 }
3977
3978                 // With FLUSHING_ALL_PEERS, callbacks will be explicitly run later
3979                 if ( $flush !== self::FLUSHING_ALL_PEERS ) {
3980                         $this->runOnTransactionIdleCallbacks( self::TRIGGER_COMMIT );
3981                         $this->runTransactionListenerCallbacks( self::TRIGGER_COMMIT );
3982                 }
3983         }
3984
3985         /**
3986          * Issues the COMMIT command to the database server.
3987          *
3988          * @see Database::commit()
3989          * @param string $fname
3990          */
3991         protected function doCommit( $fname ) {
3992                 if ( $this->trxLevel ) {
3993                         $this->query( 'COMMIT', $fname );
3994                         $this->trxLevel = 0;
3995                 }
3996         }
3997
3998         final public function rollback( $fname = __METHOD__, $flush = '' ) {
3999                 $trxActive = $this->trxLevel;
4000
4001                 if ( $flush !== self::FLUSHING_INTERNAL && $flush !== self::FLUSHING_ALL_PEERS ) {
4002                         if ( $this->getFlag( self::DBO_TRX ) ) {
4003                                 throw new DBUnexpectedError(
4004                                         $this,
4005                                         "$fname: Expected mass rollback of all peer transactions (DBO_TRX set)."
4006                                 );
4007                         }
4008                 }
4009
4010                 if ( $trxActive ) {
4011                         $this->assertHasConnectionHandle();
4012
4013                         $this->doRollback( $fname );
4014                         $this->trxStatus = self::STATUS_TRX_NONE;
4015                         $this->trxAtomicLevels = [];
4016                         // Estimate the RTT via a query now that trxStatus is OK
4017                         $writeTime = $this->pingAndCalculateLastTrxApplyTime();
4018
4019                         if ( $this->trxDoneWrites ) {
4020                                 $this->trxProfiler->transactionWritingOut(
4021                                         $this->server,
4022                                         $this->getDomainID(),
4023                                         $this->trxShortId,
4024                                         $writeTime,
4025                                         $this->trxWriteAffectedRows
4026                                 );
4027                         }
4028                 }
4029
4030                 // Clear any commit-dependant callbacks. They might even be present
4031                 // only due to transaction rounds, with no SQL transaction being active
4032                 $this->trxIdleCallbacks = [];
4033                 $this->trxPreCommitCallbacks = [];
4034
4035                 // With FLUSHING_ALL_PEERS, callbacks will be explicitly run later
4036                 if ( $trxActive && $flush !== self::FLUSHING_ALL_PEERS ) {
4037                         try {
4038                                 $this->runOnTransactionIdleCallbacks( self::TRIGGER_ROLLBACK );
4039                         } catch ( Exception $e ) {
4040                                 // already logged; finish and let LoadBalancer move on during mass-rollback
4041                         }
4042                         try {
4043                                 $this->runTransactionListenerCallbacks( self::TRIGGER_ROLLBACK );
4044                         } catch ( Exception $e ) {
4045                                 // already logged; let LoadBalancer move on during mass-rollback
4046                         }
4047
4048                         $this->affectedRowCount = 0; // for the sake of consistency
4049                 }
4050         }
4051
4052         /**
4053          * Issues the ROLLBACK command to the database server.
4054          *
4055          * @see Database::rollback()
4056          * @param string $fname
4057          */
4058         protected function doRollback( $fname ) {
4059                 if ( $this->trxLevel ) {
4060                         # Disconnects cause rollback anyway, so ignore those errors
4061                         $ignoreErrors = true;
4062                         $this->query( 'ROLLBACK', $fname, $ignoreErrors );
4063                         $this->trxLevel = 0;
4064                 }
4065         }
4066
4067         public function flushSnapshot( $fname = __METHOD__ ) {
4068                 if ( $this->writesOrCallbacksPending() || $this->explicitTrxActive() ) {
4069                         // This only flushes transactions to clear snapshots, not to write data
4070                         $fnames = implode( ', ', $this->pendingWriteAndCallbackCallers() );
4071                         throw new DBUnexpectedError(
4072                                 $this,
4073                                 "$fname: Cannot flush snapshot because writes are pending ($fnames)."
4074                         );
4075                 }
4076
4077                 $this->commit( $fname, self::FLUSHING_INTERNAL );
4078         }
4079
4080         public function explicitTrxActive() {
4081                 return $this->trxLevel && ( $this->trxAtomicLevels || !$this->trxAutomatic );
4082         }
4083
4084         public function duplicateTableStructure(
4085                 $oldName, $newName, $temporary = false, $fname = __METHOD__
4086         ) {
4087                 throw new RuntimeException( __METHOD__ . ' is not implemented in descendant class' );
4088         }
4089
4090         public function listTables( $prefix = null, $fname = __METHOD__ ) {
4091                 throw new RuntimeException( __METHOD__ . ' is not implemented in descendant class' );
4092         }
4093
4094         public function listViews( $prefix = null, $fname = __METHOD__ ) {
4095                 throw new RuntimeException( __METHOD__ . ' is not implemented in descendant class' );
4096         }
4097
4098         public function timestamp( $ts = 0 ) {
4099                 $t = new ConvertibleTimestamp( $ts );
4100                 // Let errors bubble up to avoid putting garbage in the DB
4101                 return $t->getTimestamp( TS_MW );
4102         }
4103
4104         public function timestampOrNull( $ts = null ) {
4105                 if ( is_null( $ts ) ) {
4106                         return null;
4107                 } else {
4108                         return $this->timestamp( $ts );
4109                 }
4110         }
4111
4112         public function affectedRows() {
4113                 return ( $this->affectedRowCount === null )
4114                         ? $this->fetchAffectedRowCount() // default to driver value
4115                         : $this->affectedRowCount;
4116         }
4117
4118         /**
4119          * @return int Number of retrieved rows according to the driver
4120          */
4121         abstract protected function fetchAffectedRowCount();
4122
4123         /**
4124          * Take the result from a query, and wrap it in a ResultWrapper if
4125          * necessary. Boolean values are passed through as is, to indicate success
4126          * of write queries or failure.
4127          *
4128          * Once upon a time, Database::query() returned a bare MySQL result
4129          * resource, and it was necessary to call this function to convert it to
4130          * a wrapper. Nowadays, raw database objects are never exposed to external
4131          * callers, so this is unnecessary in external code.
4132          *
4133          * @param bool|ResultWrapper|resource $result
4134          * @return bool|ResultWrapper
4135          */
4136         protected function resultObject( $result ) {
4137                 if ( !$result ) {
4138                         return false;
4139                 } elseif ( $result instanceof ResultWrapper ) {
4140                         return $result;
4141                 } elseif ( $result === true ) {
4142                         // Successful write query
4143                         return $result;
4144                 } else {
4145                         return new ResultWrapper( $this, $result );
4146                 }
4147         }
4148
4149         public function ping( &$rtt = null ) {
4150                 // Avoid hitting the server if it was hit recently
4151                 if ( $this->isOpen() && ( microtime( true ) - $this->lastPing ) < self::PING_TTL ) {
4152                         if ( !func_num_args() || $this->rttEstimate > 0 ) {
4153                                 $rtt = $this->rttEstimate;
4154                                 return true; // don't care about $rtt
4155                         }
4156                 }
4157
4158                 // This will reconnect if possible or return false if not
4159                 $this->clearFlag( self::DBO_TRX, self::REMEMBER_PRIOR );
4160                 $ok = ( $this->query( self::PING_QUERY, __METHOD__, true ) !== false );
4161                 $this->restoreFlags( self::RESTORE_PRIOR );
4162
4163                 if ( $ok ) {
4164                         $rtt = $this->rttEstimate;
4165                 }
4166
4167                 return $ok;
4168         }
4169
4170         /**
4171          * Close any existing (dead) database connection and open a new connection
4172          *
4173          * @param string $fname
4174          * @return bool True if new connection is opened successfully, false if error
4175          */
4176         protected function replaceLostConnection( $fname ) {
4177                 $this->closeConnection();
4178                 $this->opened = false;
4179                 $this->conn = false;
4180                 try {
4181                         $this->open(
4182                                 $this->server,
4183                                 $this->user,
4184                                 $this->password,
4185                                 $this->getDBname(),
4186                                 $this->dbSchema(),
4187                                 $this->tablePrefix()
4188                         );
4189                         $this->lastPing = microtime( true );
4190                         $ok = true;
4191
4192                         $this->connLogger->warning(
4193                                 $fname . ': lost connection to {dbserver}; reconnected',
4194                                 [
4195                                         'dbserver' => $this->getServer(),
4196                                         'trace' => ( new RuntimeException() )->getTraceAsString()
4197                                 ]
4198                         );
4199                 } catch ( DBConnectionError $e ) {
4200                         $ok = false;
4201
4202                         $this->connLogger->error(
4203                                 $fname . ': lost connection to {dbserver} permanently',
4204                                 [ 'dbserver' => $this->getServer() ]
4205                         );
4206                 }
4207
4208                 $this->handleSessionLoss();
4209
4210                 return $ok;
4211         }
4212
4213         public function getSessionLagStatus() {
4214                 return $this->getRecordedTransactionLagStatus() ?: $this->getApproximateLagStatus();
4215         }
4216
4217         /**
4218          * Get the replica DB lag when the current transaction started
4219          *
4220          * This is useful when transactions might use snapshot isolation
4221          * (e.g. REPEATABLE-READ in innodb), so the "real" lag of that data
4222          * is this lag plus transaction duration. If they don't, it is still
4223          * safe to be pessimistic. This returns null if there is no transaction.
4224          *
4225          * This returns null if the lag status for this transaction was not yet recorded.
4226          *
4227          * @return array|null ('lag': seconds or false on error, 'since': UNIX timestamp of BEGIN)
4228          * @since 1.27
4229          */
4230         final protected function getRecordedTransactionLagStatus() {
4231                 return ( $this->trxLevel && $this->trxReplicaLag !== null )
4232                         ? [ 'lag' => $this->trxReplicaLag, 'since' => $this->trxTimestamp() ]
4233                         : null;
4234         }
4235
4236         /**
4237          * Get a replica DB lag estimate for this server
4238          *
4239          * @return array ('lag': seconds or false on error, 'since': UNIX timestamp of estimate)
4240          * @since 1.27
4241          */
4242         protected function getApproximateLagStatus() {
4243                 return [
4244                         'lag'   => $this->getLBInfo( 'replica' ) ? $this->getLag() : 0,
4245                         'since' => microtime( true )
4246                 ];
4247         }
4248
4249         /**
4250          * Merge the result of getSessionLagStatus() for several DBs
4251          * using the most pessimistic values to estimate the lag of
4252          * any data derived from them in combination
4253          *
4254          * This is information is useful for caching modules
4255          *
4256          * @see WANObjectCache::set()
4257          * @see WANObjectCache::getWithSetCallback()
4258          *
4259          * @param IDatabase $db1
4260          * @param IDatabase|null $db2 [optional]
4261          * @return array Map of values:
4262          *   - lag: highest lag of any of the DBs or false on error (e.g. replication stopped)
4263          *   - since: oldest UNIX timestamp of any of the DB lag estimates
4264          *   - pending: whether any of the DBs have uncommitted changes
4265          * @throws DBError
4266          * @since 1.27
4267          */
4268         public static function getCacheSetOptions( IDatabase $db1, IDatabase $db2 = null ) {
4269                 $res = [ 'lag' => 0, 'since' => INF, 'pending' => false ];
4270                 foreach ( func_get_args() as $db ) {
4271                         /** @var IDatabase $db */
4272                         $status = $db->getSessionLagStatus();
4273                         if ( $status['lag'] === false ) {
4274                                 $res['lag'] = false;
4275                         } elseif ( $res['lag'] !== false ) {
4276                                 $res['lag'] = max( $res['lag'], $status['lag'] );
4277                         }
4278                         $res['since'] = min( $res['since'], $status['since'] );
4279                         $res['pending'] = $res['pending'] ?: $db->writesPending();
4280                 }
4281
4282                 return $res;
4283         }
4284
4285         public function getLag() {
4286                 return 0;
4287         }
4288
4289         public function maxListLen() {
4290                 return 0;
4291         }
4292
4293         public function encodeBlob( $b ) {
4294                 return $b;
4295         }
4296
4297         public function decodeBlob( $b ) {
4298                 if ( $b instanceof Blob ) {
4299                         $b = $b->fetch();
4300                 }
4301                 return $b;
4302         }
4303
4304         public function setSessionOptions( array $options ) {
4305         }
4306
4307         public function sourceFile(
4308                 $filename,
4309                 callable $lineCallback = null,
4310                 callable $resultCallback = null,
4311                 $fname = false,
4312                 callable $inputCallback = null
4313         ) {
4314                 Wikimedia\suppressWarnings();
4315                 $fp = fopen( $filename, 'r' );
4316                 Wikimedia\restoreWarnings();
4317
4318                 if ( $fp === false ) {
4319                         throw new RuntimeException( "Could not open \"{$filename}\".\n" );
4320                 }
4321
4322                 if ( !$fname ) {
4323                         $fname = __METHOD__ . "( $filename )";
4324                 }
4325
4326                 try {
4327                         $error = $this->sourceStream(
4328                                 $fp, $lineCallback, $resultCallback, $fname, $inputCallback );
4329                 } catch ( Exception $e ) {
4330                         fclose( $fp );
4331                         throw $e;
4332                 }
4333
4334                 fclose( $fp );
4335
4336                 return $error;
4337         }
4338
4339         public function setSchemaVars( $vars ) {
4340                 $this->schemaVars = $vars;
4341         }
4342
4343         public function sourceStream(
4344                 $fp,
4345                 callable $lineCallback = null,
4346                 callable $resultCallback = null,
4347                 $fname = __METHOD__,
4348                 callable $inputCallback = null
4349         ) {
4350                 $delimiterReset = new ScopedCallback(
4351                         function ( $delimiter ) {
4352                                 $this->delimiter = $delimiter;
4353                         },
4354                         [ $this->delimiter ]
4355                 );
4356                 $cmd = '';
4357
4358                 while ( !feof( $fp ) ) {
4359                         if ( $lineCallback ) {
4360                                 call_user_func( $lineCallback );
4361                         }
4362
4363                         $line = trim( fgets( $fp ) );
4364
4365                         if ( $line == '' ) {
4366                                 continue;
4367                         }
4368
4369                         if ( $line[0] == '-' && $line[1] == '-' ) {
4370                                 continue;
4371                         }
4372
4373                         if ( $cmd != '' ) {
4374                                 $cmd .= ' ';
4375                         }
4376
4377                         $done = $this->streamStatementEnd( $cmd, $line );
4378
4379                         $cmd .= "$line\n";
4380
4381                         if ( $done || feof( $fp ) ) {
4382                                 $cmd = $this->replaceVars( $cmd );
4383
4384                                 if ( $inputCallback ) {
4385                                         $callbackResult = $inputCallback( $cmd );
4386
4387                                         if ( is_string( $callbackResult ) || !$callbackResult ) {
4388                                                 $cmd = $callbackResult;
4389                                         }
4390                                 }
4391
4392                                 if ( $cmd ) {
4393                                         $res = $this->query( $cmd, $fname );
4394
4395                                         if ( $resultCallback ) {
4396                                                 $resultCallback( $res, $this );
4397                                         }
4398
4399                                         if ( $res === false ) {
4400                                                 $err = $this->lastError();
4401
4402                                                 return "Query \"{$cmd}\" failed with error code \"$err\".\n";
4403                                         }
4404                                 }
4405                                 $cmd = '';
4406                         }
4407                 }
4408
4409                 ScopedCallback::consume( $delimiterReset );
4410                 return true;
4411         }
4412
4413         /**
4414          * Called by sourceStream() to check if we've reached a statement end
4415          *
4416          * @param string &$sql SQL assembled so far
4417          * @param string &$newLine New line about to be added to $sql
4418          * @return bool Whether $newLine contains end of the statement
4419          */
4420         public function streamStatementEnd( &$sql, &$newLine ) {
4421                 if ( $this->delimiter ) {
4422                         $prev = $newLine;
4423                         $newLine = preg_replace(
4424                                 '/' . preg_quote( $this->delimiter, '/' ) . '$/', '', $newLine );
4425                         if ( $newLine != $prev ) {
4426                                 return true;
4427                         }
4428                 }
4429
4430                 return false;
4431         }
4432
4433         /**
4434          * Database independent variable replacement. Replaces a set of variables
4435          * in an SQL statement with their contents as given by $this->getSchemaVars().
4436          *
4437          * Supports '{$var}' `{$var}` and / *$var* / (without the spaces) style variables.
4438          *
4439          * - '{$var}' should be used for text and is passed through the database's
4440          *   addQuotes method.
4441          * - `{$var}` should be used for identifiers (e.g. table and database names).
4442          *   It is passed through the database's addIdentifierQuotes method which
4443          *   can be overridden if the database uses something other than backticks.
4444          * - / *_* / or / *$wgDBprefix* / passes the name that follows through the
4445          *   database's tableName method.
4446          * - / *i* / passes the name that follows through the database's indexName method.
4447          * - In all other cases, / *$var* / is left unencoded. Except for table options,
4448          *   its use should be avoided. In 1.24 and older, string encoding was applied.
4449          *
4450          * @param string $ins SQL statement to replace variables in
4451          * @return string The new SQL statement with variables replaced
4452          */
4453         protected function replaceVars( $ins ) {
4454                 $vars = $this->getSchemaVars();
4455                 return preg_replace_callback(
4456                         '!
4457                                 /\* (\$wgDBprefix|[_i]) \*/ (\w*) | # 1-2. tableName, indexName
4458                                 \'\{\$ (\w+) }\'                  | # 3. addQuotes
4459                                 `\{\$ (\w+) }`                    | # 4. addIdentifierQuotes
4460                                 /\*\$ (\w+) \*/                     # 5. leave unencoded
4461                         !x',
4462                         function ( $m ) use ( $vars ) {
4463                                 // Note: Because of <https://bugs.php.net/bug.php?id=51881>,
4464                                 // check for both nonexistent keys *and* the empty string.
4465                                 if ( isset( $m[1] ) && $m[1] !== '' ) {
4466                                         if ( $m[1] === 'i' ) {
4467                                                 return $this->indexName( $m[2] );
4468                                         } else {
4469                                                 return $this->tableName( $m[2] );
4470                                         }
4471                                 } elseif ( isset( $m[3] ) && $m[3] !== '' && array_key_exists( $m[3], $vars ) ) {
4472                                         return $this->addQuotes( $vars[$m[3]] );
4473                                 } elseif ( isset( $m[4] ) && $m[4] !== '' && array_key_exists( $m[4], $vars ) ) {
4474                                         return $this->addIdentifierQuotes( $vars[$m[4]] );
4475                                 } elseif ( isset( $m[5] ) && $m[5] !== '' && array_key_exists( $m[5], $vars ) ) {
4476                                         return $vars[$m[5]];
4477                                 } else {
4478                                         return $m[0];
4479                                 }
4480                         },
4481                         $ins
4482                 );
4483         }
4484
4485         /**
4486          * Get schema variables. If none have been set via setSchemaVars(), then
4487          * use some defaults from the current object.
4488          *
4489          * @return array
4490          */
4491         protected function getSchemaVars() {
4492                 if ( $this->schemaVars ) {
4493                         return $this->schemaVars;
4494                 } else {
4495                         return $this->getDefaultSchemaVars();
4496                 }
4497         }
4498
4499         /**
4500          * Get schema variables to use if none have been set via setSchemaVars().
4501          *
4502          * Override this in derived classes to provide variables for tables.sql
4503          * and SQL patch files.
4504          *
4505          * @return array
4506          */
4507         protected function getDefaultSchemaVars() {
4508                 return [];
4509         }
4510
4511         public function lockIsFree( $lockName, $method ) {
4512                 // RDBMs methods for checking named locks may or may not count this thread itself.
4513                 // In MySQL, IS_FREE_LOCK() returns 0 if the thread already has the lock. This is
4514                 // the behavior choosen by the interface for this method.
4515                 return !isset( $this->namedLocksHeld[$lockName] );
4516         }
4517
4518         public function lock( $lockName, $method, $timeout = 5 ) {
4519                 $this->namedLocksHeld[$lockName] = 1;
4520
4521                 return true;
4522         }
4523
4524         public function unlock( $lockName, $method ) {
4525                 unset( $this->namedLocksHeld[$lockName] );
4526
4527                 return true;
4528         }
4529
4530         public function getScopedLockAndFlush( $lockKey, $fname, $timeout ) {
4531                 if ( $this->writesOrCallbacksPending() ) {
4532                         // This only flushes transactions to clear snapshots, not to write data
4533                         $fnames = implode( ', ', $this->pendingWriteAndCallbackCallers() );
4534                         throw new DBUnexpectedError(
4535                                 $this,
4536                                 "$fname: Cannot flush pre-lock snapshot because writes are pending ($fnames)."
4537                         );
4538                 }
4539
4540                 if ( !$this->lock( $lockKey, $fname, $timeout ) ) {
4541                         return null;
4542                 }
4543
4544                 $unlocker = new ScopedCallback( function () use ( $lockKey, $fname ) {
4545                         if ( $this->trxLevel() ) {
4546                                 // There is a good chance an exception was thrown, causing any early return
4547                                 // from the caller. Let any error handler get a chance to issue rollback().
4548                                 // If there isn't one, let the error bubble up and trigger server-side rollback.
4549                                 $this->onTransactionResolution(
4550                                         function () use ( $lockKey, $fname ) {
4551                                                 $this->unlock( $lockKey, $fname );
4552                                         },
4553                                         $fname
4554                                 );
4555                         } else {
4556                                 $this->unlock( $lockKey, $fname );
4557                         }
4558                 } );
4559
4560                 $this->commit( $fname, self::FLUSHING_INTERNAL );
4561
4562                 return $unlocker;
4563         }
4564
4565         public function namedLocksEnqueue() {
4566                 return false;
4567         }
4568
4569         public function tableLocksHaveTransactionScope() {
4570                 return true;
4571         }
4572
4573         final public function lockTables( array $read, array $write, $method ) {
4574                 if ( $this->writesOrCallbacksPending() ) {
4575                         throw new DBUnexpectedError( $this, "Transaction writes or callbacks still pending." );
4576                 }
4577
4578                 if ( $this->tableLocksHaveTransactionScope() ) {
4579                         $this->startAtomic( $method );
4580                 }
4581
4582                 return $this->doLockTables( $read, $write, $method );
4583         }
4584
4585         /**
4586          * Helper function for lockTables() that handles the actual table locking
4587          *
4588          * @param array $read Array of tables to lock for read access
4589          * @param array $write Array of tables to lock for write access
4590          * @param string $method Name of caller
4591          * @return true
4592          */
4593         protected function doLockTables( array $read, array $write, $method ) {
4594                 return true;
4595         }
4596
4597         final public function unlockTables( $method ) {
4598                 if ( $this->tableLocksHaveTransactionScope() ) {
4599                         $this->endAtomic( $method );
4600
4601                         return true; // locks released on COMMIT/ROLLBACK
4602                 }
4603
4604                 return $this->doUnlockTables( $method );
4605         }
4606
4607         /**
4608          * Helper function for unlockTables() that handles the actual table unlocking
4609          *
4610          * @param string $method Name of caller
4611          * @return true
4612          */
4613         protected function doUnlockTables( $method ) {
4614                 return true;
4615         }
4616
4617         /**
4618          * Delete a table
4619          * @param string $tableName
4620          * @param string $fName
4621          * @return bool|ResultWrapper
4622          * @since 1.18
4623          */
4624         public function dropTable( $tableName, $fName = __METHOD__ ) {
4625                 if ( !$this->tableExists( $tableName, $fName ) ) {
4626                         return false;
4627                 }
4628                 $sql = "DROP TABLE " . $this->tableName( $tableName ) . " CASCADE";
4629
4630                 return $this->query( $sql, $fName );
4631         }
4632
4633         public function getInfinity() {
4634                 return 'infinity';
4635         }
4636
4637         public function encodeExpiry( $expiry ) {
4638                 return ( $expiry == '' || $expiry == 'infinity' || $expiry == $this->getInfinity() )
4639                         ? $this->getInfinity()
4640                         : $this->timestamp( $expiry );
4641         }
4642
4643         public function decodeExpiry( $expiry, $format = TS_MW ) {
4644                 if ( $expiry == '' || $expiry == 'infinity' || $expiry == $this->getInfinity() ) {
4645                         return 'infinity';
4646                 }
4647
4648                 return ConvertibleTimestamp::convert( $format, $expiry );
4649         }
4650
4651         public function setBigSelects( $value = true ) {
4652                 // no-op
4653         }
4654
4655         public function isReadOnly() {
4656                 return ( $this->getReadOnlyReason() !== false );
4657         }
4658
4659         /**
4660          * @return string|bool Reason this DB is read-only or false if it is not
4661          */
4662         protected function getReadOnlyReason() {
4663                 $reason = $this->getLBInfo( 'readOnlyReason' );
4664
4665                 return is_string( $reason ) ? $reason : false;
4666         }
4667
4668         public function setTableAliases( array $aliases ) {
4669                 $this->tableAliases = $aliases;
4670         }
4671
4672         public function setIndexAliases( array $aliases ) {
4673                 $this->indexAliases = $aliases;
4674         }
4675
4676         /**
4677          * Get the underlying binding connection handle
4678          *
4679          * Makes sure the connection resource is set (disconnects and ping() failure can unset it).
4680          * This catches broken callers than catch and ignore disconnection exceptions.
4681          * Unlike checking isOpen(), this is safe to call inside of open().
4682          *
4683          * @return mixed
4684          * @throws DBUnexpectedError
4685          * @since 1.26
4686          */
4687         protected function getBindingHandle() {
4688                 if ( !$this->conn ) {
4689                         throw new DBUnexpectedError(
4690                                 $this,
4691                                 'DB connection was already closed or the connection dropped.'
4692                         );
4693                 }
4694
4695                 return $this->conn;
4696         }
4697
4698         /**
4699          * @since 1.19
4700          * @return string
4701          */
4702         public function __toString() {
4703                 return (string)$this->conn;
4704         }
4705
4706         /**
4707          * Make sure that copies do not share the same client binding handle
4708          * @throws DBConnectionError
4709          */
4710         public function __clone() {
4711                 $this->connLogger->warning(
4712                         "Cloning " . static::class . " is not recommended; forking connection:\n" .
4713                         ( new RuntimeException() )->getTraceAsString()
4714                 );
4715
4716                 if ( $this->isOpen() ) {
4717                         // Open a new connection resource without messing with the old one
4718                         $this->opened = false;
4719                         $this->conn = false;
4720                         $this->trxEndCallbacks = []; // don't copy
4721                         $this->handleSessionLoss(); // no trx or locks anymore
4722                         $this->open(
4723                                 $this->server,
4724                                 $this->user,
4725                                 $this->password,
4726                                 $this->getDBname(),
4727                                 $this->dbSchema(),
4728                                 $this->tablePrefix()
4729                         );
4730                         $this->lastPing = microtime( true );
4731                 }
4732         }
4733
4734         /**
4735          * Called by serialize. Throw an exception when DB connection is serialized.
4736          * This causes problems on some database engines because the connection is
4737          * not restored on unserialize.
4738          */
4739         public function __sleep() {
4740                 throw new RuntimeException( 'Database serialization may cause problems, since ' .
4741                         'the connection is not restored on wakeup.' );
4742         }
4743
4744         /**
4745          * Run a few simple sanity checks and close dangling connections
4746          */
4747         public function __destruct() {
4748                 if ( $this->trxLevel && $this->trxDoneWrites ) {
4749                         trigger_error( "Uncommitted DB writes (transaction from {$this->trxFname})." );
4750                 }
4751
4752                 $danglingWriters = $this->pendingWriteAndCallbackCallers();
4753                 if ( $danglingWriters ) {
4754                         $fnames = implode( ', ', $danglingWriters );
4755                         trigger_error( "DB transaction writes or callbacks still pending ($fnames)." );
4756                 }
4757
4758                 if ( $this->conn ) {
4759                         // Avoid connection leaks for sanity. Normally, resources close at script completion.
4760                         // The connection might already be closed in zend/hhvm by now, so suppress warnings.
4761                         Wikimedia\suppressWarnings();
4762                         $this->closeConnection();
4763                         Wikimedia\restoreWarnings();
4764                         $this->conn = false;
4765                         $this->opened = false;
4766                 }
4767         }
4768 }
4769
4770 /**
4771  * @deprecated since 1.28
4772  */
4773 class_alias( Database::class, 'DatabaseBase' );
4774
4775 /**
4776  * @deprecated since 1.29
4777  */
4778 class_alias( Database::class, 'Database' );