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 string Database that this instance is currently connected to */
  85         protected $dbName;
  86         /** @var array[] Map of (table => (dbname, schema, prefix) map) */
  87         protected $tableAliases = [];
  88         /** @var string[] Map of (index alias => index) */
  89         protected $indexAliases = [];
  90         /** @var bool Whether this PHP instance is for a CLI script */
  91         protected $cliMode;
  92         /** @var string Agent name for query profiling */
  93         protected $agent;
  94         /** @var array Parameters used by initConnection() to establish a connection */
  95         protected $connectionParams = [];
  96         /** @var BagOStuff APC cache */
  97         protected $srvCache;
  98         /** @var LoggerInterface */
  99         protected $connLogger;
 100         /** @var LoggerInterface */
 101         protected $queryLogger;
 102         /** @var callback Error logging callback */
 103         protected $errorLogger;
 104         /** @var callback Deprecation logging callback */
 105         protected $deprecationLogger;
 106
 107         /** @var resource|null Database connection */
 108         protected $conn = null;
 109         /** @var bool */
 110         protected $opened = false;
 111
 112         /** @var array[] List of (callable, method name, atomic section id) */
 113         protected $trxIdleCallbacks = [];
 114         /** @var array[] List of (callable, method name, atomic section id) */
 115         protected $trxPreCommitCallbacks = [];
 116         /** @var array[] List of (callable, method name, atomic section id) */
 117         protected $trxEndCallbacks = [];
 118         /** @var callable[] Map of (name => callable) */
 119         protected $trxRecurringCallbacks = [];
 120         /** @var bool Whether to suppress triggering of transaction end callbacks */
 121         protected $trxEndCallbacksSuppressed = false;
 122
 123         /** @var string */
 124         protected $tablePrefix = '';
 125         /** @var string */
 126         protected $schema = '';
 127         /** @var int */
 128         protected $flags;
 129         /** @var array */
 130         protected $lbInfo = [];
 131         /** @var array|bool */
 132         protected $schemaVars = false;
 133         /** @var array */
 134         protected $sessionVars = [];
 135         /** @var array|null */
 136         protected $preparedArgs;
 137         /** @var string|bool|null Stashed value of html_errors INI setting */
 138         protected $htmlErrors;
 139         /** @var string */
 140         protected $delimiter = ';';
 141         /** @var DatabaseDomain */
 142         protected $currentDomain;
 143         /** @var integer|null Rows affected by the last query to query() or its CRUD wrappers */
 144         protected $affectedRowCount;
 145
 146         /**
 147          * @var int Transaction status
 148          */
 149         protected $trxStatus = self::STATUS_TRX_NONE;
 150         /**
 151          * @var Exception|null The last error that caused the status to become STATUS_TRX_ERROR
 152          */
 153         protected $trxStatusCause;
 154         /**
 155          * @var array|null If wasKnownStatementRollbackError() prevented trxStatus from being set,
 156          *  the relevant details are stored here.
 157          */
 158         protected $trxStatusIgnoredCause;
 159         /**
 160          * Either 1 if a transaction is active or 0 otherwise.
 161          * The other Trx fields may not be meaningfull if this is 0.
 162          *
 163          * @var int
 164          */
 165         protected $trxLevel = 0;
 166         /**
 167          * Either a short hexidecimal string if a transaction is active or ""
 168          *
 169          * @var string
 170          * @see Database::trxLevel
 171          */
 172         protected $trxShortId = '';
 173         /**
 174          * The UNIX time that the transaction started. Callers can assume that if
 175          * snapshot isolation is used, then the data is *at least* up to date to that
 176          * point (possibly more up-to-date since the first SELECT defines the snapshot).
 177          *
 178          * @var float|null
 179          * @see Database::trxLevel
 180          */
 181         private $trxTimestamp = null;
 182         /** @var float Lag estimate at the time of BEGIN */
 183         private $trxReplicaLag = null;
 184         /**
 185          * Remembers the function name given for starting the most recent transaction via begin().
 186          * Used to provide additional context for error reporting.
 187          *
 188          * @var string
 189          * @see Database::trxLevel
 190          */
 191         private $trxFname = null;
 192         /**
 193          * Record if possible write queries were done in the last transaction started
 194          *
 195          * @var bool
 196          * @see Database::trxLevel
 197          */
 198         private $trxDoneWrites = false;
 199         /**
 200          * Record if the current transaction was started implicitly due to DBO_TRX being set.
 201          *
 202          * @var bool
 203          * @see Database::trxLevel
 204          */
 205         private $trxAutomatic = false;
 206         /**
 207          * Counter for atomic savepoint identifiers. Reset when a new transaction begins.
 208          *
 209          * @var int
 210          */
 211         private $trxAtomicCounter = 0;
 212         /**
 213          * Array of levels of atomicity within transactions
 214          *
 215          * @var array List of (name, unique ID, savepoint ID)
 216          */
 217         private $trxAtomicLevels = [];
 218         /**
 219          * Record if the current transaction was started implicitly by Database::startAtomic
 220          *
 221          * @var bool
 222          */
 223         private $trxAutomaticAtomic = false;
 224         /**
 225          * Track the write query callers of the current transaction
 226          *
 227          * @var string[]
 228          */
 229         private $trxWriteCallers = [];
 230         /**
 231          * @var float Seconds spent in write queries for the current transaction
 232          */
 233         private $trxWriteDuration = 0.0;
 234         /**
 235          * @var int Number of write queries for the current transaction
 236          */
 237         private $trxWriteQueryCount = 0;
 238         /**
 239          * @var int Number of rows affected by write queries for the current transaction
 240          */
 241         private $trxWriteAffectedRows = 0;
 242         /**
 243          * @var float Like trxWriteQueryCount but excludes lock-bound, easy to replicate, queries
 244          */
 245         private $trxWriteAdjDuration = 0.0;
 246         /**
 247          * @var int Number of write queries counted in trxWriteAdjDuration
 248          */
 249         private $trxWriteAdjQueryCount = 0;
 250         /**
 251          * @var float RTT time estimate
 252          */
 253         private $rttEstimate = 0.0;
 254
 255         /** @var array Map of (name => 1) for locks obtained via lock() */
 256         private $namedLocksHeld = [];
 257         /** @var array Map of (table name => 1) for TEMPORARY tables */
 258         protected $sessionTempTables = [];
 259
 260         /** @var IDatabase|null Lazy handle to the master DB this server replicates from */
 261         private $lazyMasterHandle;
 262
 263         /** @var float UNIX timestamp */
 264         protected $lastPing = 0.0;
 265
 266         /** @var int[] Prior flags member variable values */
 267         private $priorFlags = [];
 268
 269         /** @var mixed Class name or object With profileIn/profileOut methods */
 270         protected $profiler;
 271         /** @var TransactionProfiler */
 272         protected $trxProfiler;
 273
 274         /** @var int */
 275         protected $nonNativeInsertSelectBatchSize = 10000;
 276
 277         /** @var string Idiom used when a cancelable atomic section started the transaction */
 278         private static $NOT_APPLICABLE = 'n/a';
 279         /** @var string Prefix to the atomic section counter used to make savepoint IDs */
 280         private static $SAVEPOINT_PREFIX = 'wikimedia_rdbms_atomic';
 281
 282         /** @var int Transaction is in a error state requiring a full or savepoint rollback */
 283         const STATUS_TRX_ERROR = 1;
 284         /** @var int Transaction is active and in a normal state */
 285         const STATUS_TRX_OK = 2;
 286         /** @var int No transaction is active */
 287         const STATUS_TRX_NONE = 3;
 288
 289         /**
 290          * @note exceptions for missing libraries/drivers should be thrown in initConnection()
 291          * @param array $params Parameters passed from Database::factory()
 292          */
 293         protected function __construct( array $params ) {
 294                 foreach ( [ 'host', 'user', 'password', 'dbname' ] as $name ) {
 295                         $this->connectionParams[$name] = $params[$name];
 296                 }
 297
 298                 $this->schema = $params['schema'];
 299                 $this->tablePrefix = $params['tablePrefix'];
 300
 301                 $this->cliMode = $params['cliMode'];
 302                 // Agent name is added to SQL queries in a comment, so make sure it can't break out
 303                 $this->agent = str_replace( '/', '-', $params['agent'] );
 304
 305                 $this->flags = $params['flags'];
 306                 if ( $this->flags & self::DBO_DEFAULT ) {
 307                         if ( $this->cliMode ) {
 308                                 $this->flags &= ~self::DBO_TRX;
 309                         } else {
 310                                 $this->flags |= self::DBO_TRX;
 311                         }
 312                 }
 313                 // Disregard deprecated DBO_IGNORE flag (T189999)
 314                 $this->flags &= ~self::DBO_IGNORE;
 315
 316                 $this->sessionVars = $params['variables'];
 317
 318                 $this->srvCache = $params['srvCache'] ?? new HashBagOStuff();
 319
 320                 $this->profiler = $params['profiler'];
 321                 $this->trxProfiler = $params['trxProfiler'];
 322                 $this->connLogger = $params['connLogger'];
 323                 $this->queryLogger = $params['queryLogger'];
 324                 $this->errorLogger = $params['errorLogger'];
 325                 $this->deprecationLogger = $params['deprecationLogger'];
 326
 327                 if ( isset( $params['nonNativeInsertSelectBatchSize'] ) ) {
 328                         $this->nonNativeInsertSelectBatchSize = $params['nonNativeInsertSelectBatchSize'];
 329                 }
 330
 331                 // Set initial dummy domain until open() sets the final DB/prefix
 332                 $this->currentDomain = DatabaseDomain::newUnspecified();
 333         }
 334
 335         /**
 336          * Initialize the connection to the database over the wire (or to local files)
 337          *
 338          * @throws LogicException
 339          * @throws InvalidArgumentException
 340          * @throws DBConnectionError
 341          * @since 1.31
 342          */
 343         final public function initConnection() {
 344                 if ( $this->isOpen() ) {
 345                         throw new LogicException( __METHOD__ . ': already connected.' );
 346                 }
 347                 // Establish the connection
 348                 $this->doInitConnection();
 349                 // Set the domain object after open() sets the relevant fields
 350                 if ( $this->dbName != '' ) {
 351                         // Domains with server scope but a table prefix are not used by IDatabase classes
 352                         $this->currentDomain = new DatabaseDomain( $this->dbName, null, $this->tablePrefix );
 353                 }
 354         }
 355
 356         /**
 357          * Actually connect to the database over the wire (or to local files)
 358          *
 359          * @throws InvalidArgumentException
 360          * @throws DBConnectionError
 361          * @since 1.31
 362          */
 363         protected function doInitConnection() {
 364                 if ( strlen( $this->connectionParams['user'] ) ) {
 365                         $this->open(
 366                                 $this->connectionParams['host'],
 367                                 $this->connectionParams['user'],
 368                                 $this->connectionParams['password'],
 369                                 $this->connectionParams['dbname']
 370                         );
 371                 } else {
 372                         throw new InvalidArgumentException( "No database user provided." );
 373                 }
 374         }
 375
 376         /**
 377          * Open a new connection to the database (closing any existing one)
 378          *
 379          * @param string $server Database server host
 380          * @param string $user Database user name
 381          * @param string $password Database user password
 382          * @param string $dbName Database name
 383          * @return bool
 384          * @throws DBConnectionError
 385          */
 386         abstract protected function open( $server, $user, $password, $dbName );
 387
 388         /**
 389          * Construct a Database subclass instance given a database type and parameters
 390          *
 391          * This also connects to the database immediately upon object construction
 392          *
 393          * @param string $dbType A possible DB type (sqlite, mysql, postgres,...)
 394          * @param array $p Parameter map with keys:
 395          *   - host : The hostname of the DB server
 396          *   - user : The name of the database user the client operates under
 397          *   - password : The password for the database user
 398          *   - dbname : The name of the database to use where queries do not specify one.
 399          *      The database must exist or an error might be thrown. Setting this to the empty string
 400          *      will avoid any such errors and make the handle have no implicit database scope. This is
 401          *      useful for queries like SHOW STATUS, CREATE DATABASE, or DROP DATABASE. Note that a
 402          *      "database" in Postgres is rougly equivalent to an entire MySQL server. This the domain
 403          *      in which user names and such are defined, e.g. users are database-specific in Postgres.
 404          *   - schema : The database schema to use (if supported). A "schema" in Postgres is roughly
 405          *      equivalent to a "database" in MySQL. Note that MySQL and SQLite do not use schemas.
 406          *   - tablePrefix : Optional table prefix that is implicitly added on to all table names
 407          *      recognized in queries. This can be used in place of schemas for handle site farms.
 408          *   - flags : Optional bitfield of DBO_* constants that define connection, protocol,
 409          *      buffering, and transaction behavior. It is STRONGLY adviced to leave the DBO_DEFAULT
 410          *      flag in place UNLESS this this database simply acts as a key/value store.
 411          *   - driver: Optional name of a specific DB client driver. For MySQL, there is only the
 412          *      'mysqli' driver; the old one 'mysql' has been removed.
 413          *   - variables: Optional map of session variables to set after connecting. This can be
 414          *      used to adjust lock timeouts or encoding modes and the like.
 415          *   - connLogger: Optional PSR-3 logger interface instance.
 416          *   - queryLogger: Optional PSR-3 logger interface instance.
 417          *   - profiler: Optional class name or object with profileIn()/profileOut() methods.
 418          *      These will be called in query(), using a simplified version of the SQL that also
 419          *      includes the agent as a SQL comment.
 420          *   - trxProfiler: Optional TransactionProfiler instance.
 421          *   - errorLogger: Optional callback that takes an Exception and logs it.
 422          *   - deprecationLogger: Optional callback that takes a string and logs it.
 423          *   - cliMode: Whether to consider the execution context that of a CLI script.
 424          *   - agent: Optional name used to identify the end-user in query profiling/logging.
 425          *   - srvCache: Optional BagOStuff instance to an APC-style cache.
 426          *   - nonNativeInsertSelectBatchSize: Optional batch size for non-native INSERT SELECT emulation.
 427          * @param int $connect One of the class constants (NEW_CONNECTED, NEW_UNCONNECTED) [optional]
 428          * @return Database|null If the database driver or extension cannot be found
 429          * @throws InvalidArgumentException If the database driver or extension cannot be found
 430          * @since 1.18
 431          */
 432         final public static function factory( $dbType, $p = [], $connect = self::NEW_CONNECTED ) {
 433                 $class = self::getClass( $dbType, $p['driver'] ?? null );
 434
 435                 if ( class_exists( $class ) && is_subclass_of( $class, IDatabase::class ) ) {
 436                         // Resolve some defaults for b/c
 437                         $p['host'] = $p['host'] ?? false;
 438                         $p['user'] = $p['user'] ?? false;
 439                         $p['password'] = $p['password'] ?? false;
 440                         $p['dbname'] = $p['dbname'] ?? false;
 441                         $p['flags'] = $p['flags'] ?? 0;
 442                         $p['variables'] = $p['variables'] ?? [];
 443                         $p['tablePrefix'] = $p['tablePrefix'] ?? '';
 444                         $p['schema'] = $p['schema'] ?? '';
 445                         $p['cliMode'] = $p['cliMode'] ?? ( PHP_SAPI === 'cli' || PHP_SAPI === 'phpdbg' );
 446                         $p['agent'] = $p['agent'] ?? '';
 447                         if ( !isset( $p['connLogger'] ) ) {
 448                                 $p['connLogger'] = new NullLogger();
 449                         }
 450                         if ( !isset( $p['queryLogger'] ) ) {
 451                                 $p['queryLogger'] = new NullLogger();
 452                         }
 453                         $p['profiler'] = $p['profiler'] ?? null;
 454                         if ( !isset( $p['trxProfiler'] ) ) {
 455                                 $p['trxProfiler'] = new TransactionProfiler();
 456                         }
 457                         if ( !isset( $p['errorLogger'] ) ) {
 458                                 $p['errorLogger'] = function ( Exception $e ) {
 459                                         trigger_error( get_class( $e ) . ': ' . $e->getMessage(), E_USER_WARNING );
 460                                 };
 461                         }
 462                         if ( !isset( $p['deprecationLogger'] ) ) {
 463                                 $p['deprecationLogger'] = function ( $msg ) {
 464                                         trigger_error( $msg, E_USER_DEPRECATED );
 465                                 };
 466                         }
 467
 468                         /** @var Database $conn */
 469                         $conn = new $class( $p );
 470                         if ( $connect == self::NEW_CONNECTED ) {
 471                                 $conn->initConnection();
 472                         }
 473                 } else {
 474                         $conn = null;
 475                 }
 476
 477                 return $conn;
 478         }
 479
 480         /**
 481          * @param string $dbType A possible DB type (sqlite, mysql, postgres,...)
 482          * @param string|null $driver Optional name of a specific DB client driver
 483          * @return array Map of (Database::ATTRIBUTE_* constant => value) for all such constants
 484          * @throws InvalidArgumentException
 485          * @since 1.31
 486          */
 487         final public static function attributesFromType( $dbType, $driver = null ) {
 488                 static $defaults = [ self::ATTR_DB_LEVEL_LOCKING => false ];
 489
 490                 $class = self::getClass( $dbType, $driver );
 491
 492                 return call_user_func( [ $class, 'getAttributes' ] ) + $defaults;
 493         }
 494
 495         /**
 496          * @param string $dbType A possible DB type (sqlite, mysql, postgres,...)
 497          * @param string|null $driver Optional name of a specific DB client driver
 498          * @return string Database subclass name to use
 499          * @throws InvalidArgumentException
 500          */
 501         private static function getClass( $dbType, $driver = null ) {
 502                 // For database types with built-in support, the below maps type to IDatabase
 503                 // implementations. For types with multipe driver implementations (PHP extensions),
 504                 // an array can be used, keyed by extension name. In case of an array, the
 505                 // optional 'driver' parameter can be used to force a specific driver. Otherwise,
 506                 // we auto-detect the first available driver. For types without built-in support,
 507                 // an class named "Database<Type>" us used, eg. DatabaseFoo for type 'foo'.
 508                 static $builtinTypes = [
 509                         'mssql' => DatabaseMssql::class,
 510                         'mysql' => [ 'mysqli' => DatabaseMysqli::class ],
 511                         'sqlite' => DatabaseSqlite::class,
 512                         'postgres' => DatabasePostgres::class,
 513                 ];
 514
 515                 $dbType = strtolower( $dbType );
 516                 $class = false;
 517
 518                 if ( isset( $builtinTypes[$dbType] ) ) {
 519                         $possibleDrivers = $builtinTypes[$dbType];
 520                         if ( is_string( $possibleDrivers ) ) {
 521                                 $class = $possibleDrivers;
 522                         } else {
 523                                 if ( (string)$driver !== '' ) {
 524                                         if ( !isset( $possibleDrivers[$driver] ) ) {
 525                                                 throw new InvalidArgumentException( __METHOD__ .
 526                                                         " type '$dbType' does not support driver '{$driver}'" );
 527                                         } else {
 528                                                 $class = $possibleDrivers[$driver];
 529                                         }
 530                                 } else {
 531                                         foreach ( $possibleDrivers as $posDriver => $possibleClass ) {
 532                                                 if ( extension_loaded( $posDriver ) ) {
 533                                                         $class = $possibleClass;
 534                                                         break;
 535                                                 }
 536                                         }
 537                                 }
 538                         }
 539                 } else {
 540                         $class = 'Database' . ucfirst( $dbType );
 541                 }
 542
 543                 if ( $class === false ) {
 544                         throw new InvalidArgumentException( __METHOD__ .
 545                                 " no viable database extension found for type '$dbType'" );
 546                 }
 547
 548                 return $class;
 549         }
 550
 551         /**
 552          * @return array Map of (Database::ATTRIBUTE_* constant => value
 553          * @since 1.31
 554          */
 555         protected static function getAttributes() {
 556                 return [];
 557         }
 558
 559         /**
 560          * Set the PSR-3 logger interface to use for query logging. (The logger
 561          * interfaces for connection logging and error logging can be set with the
 562          * constructor.)
 563          *
 564          * @param LoggerInterface $logger
 565          */
 566         public function setLogger( LoggerInterface $logger ) {
 567                 $this->queryLogger = $logger;
 568         }
 569
 570         public function getServerInfo() {
 571                 return $this->getServerVersion();
 572         }
 573
 574         public function bufferResults( $buffer = null ) {
 575                 $res = !$this->getFlag( self::DBO_NOBUFFER );
 576                 if ( $buffer !== null ) {
 577                         $buffer
 578                                 ? $this->clearFlag( self::DBO_NOBUFFER )
 579                                 : $this->setFlag( self::DBO_NOBUFFER );
 580                 }
 581
 582                 return $res;
 583         }
 584
 585         public function trxLevel() {
 586                 return $this->trxLevel;
 587         }
 588
 589         public function trxTimestamp() {
 590                 return $this->trxLevel ? $this->trxTimestamp : null;
 591         }
 592
 593         /**
 594          * @return int One of the STATUS_TRX_* class constants
 595          * @since 1.31
 596          */
 597         public function trxStatus() {
 598                 return $this->trxStatus;
 599         }
 600
 601         public function tablePrefix( $prefix = null ) {
 602                 $old = $this->tablePrefix;
 603                 if ( $prefix !== null ) {
 604                         $this->tablePrefix = $prefix;
 605                         $this->currentDomain = ( $this->dbName != '' )
 606                                 ? new DatabaseDomain( $this->dbName, null, $this->tablePrefix )
 607                                 : DatabaseDomain::newUnspecified();
 608                 }
 609
 610                 return $old;
 611         }
 612
 613         public function dbSchema( $schema = null ) {
 614                 $old = $this->schema;
 615                 if ( $schema !== null ) {
 616                         $this->schema = $schema;
 617                 }
 618
 619                 return $old;
 620         }
 621
 622         public function getLBInfo( $name = null ) {
 623                 if ( is_null( $name ) ) {
 624                         return $this->lbInfo;
 625                 } else {
 626                         if ( array_key_exists( $name, $this->lbInfo ) ) {
 627                                 return $this->lbInfo[$name];
 628                         } else {
 629                                 return null;
 630                         }
 631                 }
 632         }
 633
 634         public function setLBInfo( $name, $value = null ) {
 635                 if ( is_null( $value ) ) {
 636                         $this->lbInfo = $name;
 637                 } else {
 638                         $this->lbInfo[$name] = $value;
 639                 }
 640         }
 641
 642         public function setLazyMasterHandle( IDatabase $conn ) {
 643                 $this->lazyMasterHandle = $conn;
 644         }
 645
 646         /**
 647          * @return IDatabase|null
 648          * @see setLazyMasterHandle()
 649          * @since 1.27
 650          */
 651         protected function getLazyMasterHandle() {
 652                 return $this->lazyMasterHandle;
 653         }
 654
 655         public function implicitGroupby() {
 656                 return true;
 657         }
 658
 659         public function implicitOrderby() {
 660                 return true;
 661         }
 662
 663         public function lastQuery() {
 664                 return $this->lastQuery;
 665         }
 666
 667         public function doneWrites() {
 668                 return (bool)$this->lastWriteTime;
 669         }
 670
 671         public function lastDoneWrites() {
 672                 return $this->lastWriteTime ?: false;
 673         }
 674
 675         public function writesPending() {
 676                 return $this->trxLevel && $this->trxDoneWrites;
 677         }
 678
 679         public function writesOrCallbacksPending() {
 680                 return $this->trxLevel && (
 681                         $this->trxDoneWrites ||
 682                         $this->trxIdleCallbacks ||
 683                         $this->trxPreCommitCallbacks ||
 684                         $this->trxEndCallbacks
 685                 );
 686         }
 687
 688         public function preCommitCallbacksPending() {
 689                 return $this->trxLevel && $this->trxPreCommitCallbacks;
 690         }
 691
 692         /**
 693          * @return string|null
 694          */
 695         final protected function getTransactionRoundId() {
 696                 // If transaction round participation is enabled, see if one is active
 697                 if ( $this->getFlag( self::DBO_TRX ) ) {
 698                         $id = $this->getLBInfo( 'trxRoundId' );
 699
 700                         return is_string( $id ) ? $id : null;
 701                 }
 702
 703                 return null;
 704         }
 705
 706         public function pendingWriteQueryDuration( $type = self::ESTIMATE_TOTAL ) {
 707                 if ( !$this->trxLevel ) {
 708                         return false;
 709                 } elseif ( !$this->trxDoneWrites ) {
 710                         return 0.0;
 711                 }
 712
 713                 switch ( $type ) {
 714                         case self::ESTIMATE_DB_APPLY:
 715                                 $this->ping( $rtt );
 716                                 $rttAdjTotal = $this->trxWriteAdjQueryCount * $rtt;
 717                                 $applyTime = max( $this->trxWriteAdjDuration - $rttAdjTotal, 0 );
 718                                 // For omitted queries, make them count as something at least
 719                                 $omitted = $this->trxWriteQueryCount - $this->trxWriteAdjQueryCount;
 720                                 $applyTime += self::TINY_WRITE_SEC * $omitted;
 721
 722                                 return $applyTime;
 723                         default: // everything
 724                                 return $this->trxWriteDuration;
 725                 }
 726         }
 727
 728         public function pendingWriteCallers() {
 729                 return $this->trxLevel ? $this->trxWriteCallers : [];
 730         }
 731
 732         public function pendingWriteRowsAffected() {
 733                 return $this->trxWriteAffectedRows;
 734         }
 735
 736         /**
 737          * List the methods that have write queries or callbacks for the current transaction
 738          *
 739          * This method should not be used outside of Database/LoadBalancer
 740          *
 741          * @return string[]
 742          * @since 1.32
 743          */
 744         public function pendingWriteAndCallbackCallers() {
 745                 $fnames = $this->pendingWriteCallers();
 746                 foreach ( [
 747                         $this->trxIdleCallbacks,
 748                         $this->trxPreCommitCallbacks,
 749                         $this->trxEndCallbacks
 750                 ] as $callbacks ) {
 751                         foreach ( $callbacks as $callback ) {
 752                                 $fnames[] = $callback[1];
 753                         }
 754                 }
 755
 756                 return $fnames;
 757         }
 758
 759         /**
 760          * @return string
 761          */
 762         private function flatAtomicSectionList() {
 763                 return array_reduce( $this->trxAtomicLevels, function ( $accum, $v ) {
 764                         return $accum === null ? $v[0] : "$accum, " . $v[0];
 765                 } );
 766         }
 767
 768         public function isOpen() {
 769                 return $this->opened;
 770         }
 771
 772         public function setFlag( $flag, $remember = self::REMEMBER_NOTHING ) {
 773                 if ( ( $flag & self::DBO_IGNORE ) ) {
 774                         throw new UnexpectedValueException( "Modifying DBO_IGNORE is not allowed." );
 775                 }
 776
 777                 if ( $remember === self::REMEMBER_PRIOR ) {
 778                         array_push( $this->priorFlags, $this->flags );
 779                 }
 780                 $this->flags |= $flag;
 781         }
 782
 783         public function clearFlag( $flag, $remember = self::REMEMBER_NOTHING ) {
 784                 if ( ( $flag & self::DBO_IGNORE ) ) {
 785                         throw new UnexpectedValueException( "Modifying DBO_IGNORE is not allowed." );
 786                 }
 787
 788                 if ( $remember === self::REMEMBER_PRIOR ) {
 789                         array_push( $this->priorFlags, $this->flags );
 790                 }
 791                 $this->flags &= ~$flag;
 792         }
 793
 794         public function restoreFlags( $state = self::RESTORE_PRIOR ) {
 795                 if ( !$this->priorFlags ) {
 796                         return;
 797                 }
 798
 799                 if ( $state === self::RESTORE_INITIAL ) {
 800                         $this->flags = reset( $this->priorFlags );
 801                         $this->priorFlags = [];
 802                 } else {
 803                         $this->flags = array_pop( $this->priorFlags );
 804                 }
 805         }
 806
 807         public function getFlag( $flag ) {
 808                 return !!( $this->flags & $flag );
 809         }
 810
 811         /**
 812          * @param string $name Class field name
 813          * @return mixed
 814          * @deprecated Since 1.28
 815          */
 816         public function getProperty( $name ) {
 817                 return $this->$name;
 818         }
 819
 820         public function getDomainID() {
 821                 return $this->currentDomain->getId();
 822         }
 823
 824         final public function getWikiID() {
 825                 return $this->getDomainID();
 826         }
 827
 828         /**
 829          * Get information about an index into an object
 830          * @param string $table Table name
 831          * @param string $index Index name
 832          * @param string $fname Calling function name
 833          * @return mixed Database-specific index description class or false if the index does not exist
 834          */
 835         abstract function indexInfo( $table, $index, $fname = __METHOD__ );
 836
 837         /**
 838          * Wrapper for addslashes()
 839          *
 840          * @param string $s String to be slashed.
 841          * @return string Slashed string.
 842          */
 843         abstract function strencode( $s );
 844
 845         /**
 846          * Set a custom error handler for logging errors during database connection
 847          */
 848         protected function installErrorHandler() {
 849                 $this->phpError = false;
 850                 $this->htmlErrors = ini_set( 'html_errors', '0' );
 851                 set_error_handler( [ $this, 'connectionErrorLogger' ] );
 852         }
 853
 854         /**
 855          * Restore the previous error handler and return the last PHP error for this DB
 856          *
 857          * @return bool|string
 858          */
 859         protected function restoreErrorHandler() {
 860                 restore_error_handler();
 861                 if ( $this->htmlErrors !== false ) {
 862                         ini_set( 'html_errors', $this->htmlErrors );
 863                 }
 864
 865                 return $this->getLastPHPError();
 866         }
 867
 868         /**
 869          * @return string|bool Last PHP error for this DB (typically connection errors)
 870          */
 871         protected function getLastPHPError() {
 872                 if ( $this->phpError ) {
 873                         $error = preg_replace( '!\[<a.*</a>\]!', '', $this->phpError );
 874                         $error = preg_replace( '!^.*?:\s?(.*)$!', '$1', $error );
 875
 876                         return $error;
 877                 }
 878
 879                 return false;
 880         }
 881
 882         /**
 883          * Error handler for logging errors during database connection
 884          * This method should not be used outside of Database classes
 885          *
 886          * @param int $errno
 887          * @param string $errstr
 888          */
 889         public function connectionErrorLogger( $errno, $errstr ) {
 890                 $this->phpError = $errstr;
 891         }
 892
 893         /**
 894          * Create a log context to pass to PSR-3 logger functions.
 895          *
 896          * @param array $extras Additional data to add to context
 897          * @return array
 898          */
 899         protected function getLogContext( array $extras = [] ) {
 900                 return array_merge(
 901                         [
 902                                 'db_server' => $this->server,
 903                                 'db_name' => $this->dbName,
 904                                 'db_user' => $this->user,
 905                         ],
 906                         $extras
 907                 );
 908         }
 909
 910         final public function close() {
 911                 $exception = null; // error to throw after disconnecting
 912
 913                 if ( $this->conn ) {
 914                         // Resolve any dangling transaction first
 915                         if ( $this->trxLevel ) {
 916                                 if ( $this->trxAtomicLevels ) {
 917                                         // Cannot let incomplete atomic sections be committed
 918                                         $levels = $this->flatAtomicSectionList();
 919                                         $exception = new DBUnexpectedError(
 920                                                 $this,
 921                                                 __METHOD__ . ": atomic sections $levels are still open."
 922                                         );
 923                                 } elseif ( $this->trxAutomatic ) {
 924                                         // Only the connection manager can commit non-empty DBO_TRX transactions
 925                                         if ( $this->writesOrCallbacksPending() ) {
 926                                                 $exception = new DBUnexpectedError(
 927                                                         $this,
 928                                                         __METHOD__ .
 929                                                         ": mass commit/rollback of peer transaction required (DBO_TRX set)."
 930                                                 );
 931                                         }
 932                                 } elseif ( $this->trxLevel ) {
 933                                         // Commit explicit transactions as if this was commit()
 934                                         $this->queryLogger->warning(
 935                                                 __METHOD__ . ": writes or callbacks still pending.",
 936                                                 [ 'trace' => ( new RuntimeException() )->getTraceAsString() ]
 937                                         );
 938                                 }
 939
 940                                 if ( $this->trxEndCallbacksSuppressed ) {
 941                                         $exception = $exception ?: new DBUnexpectedError(
 942                                                 $this,
 943                                                 __METHOD__ . ': callbacks are suppressed; cannot properly commit.'
 944                                         );
 945                                 }
 946
 947                                 // Commit or rollback the changes and run any callbacks as needed
 948                                 if ( $this->trxStatus === self::STATUS_TRX_OK && !$exception ) {
 949                                         $this->commit(
 950                                                 __METHOD__,
 951                                                 $this->trxAutomatic ? self::FLUSHING_INTERNAL : self::FLUSHING_ONE
 952                                         );
 953                                 } else {
 954                                         $this->rollback( __METHOD__, self::FLUSHING_INTERNAL );
 955                                 }
 956                         }
 957
 958                         // Close the actual connection in the binding handle
 959                         $closed = $this->closeConnection();
 960                         $this->conn = false;
 961                 } else {
 962                         $closed = true; // already closed; nothing to do
 963                 }
 964
 965                 $this->opened = false;
 966
 967                 // Throw any unexpected errors after having disconnected
 968                 if ( $exception instanceof Exception ) {
 969                         throw $exception;
 970                 }
 971
 972                 // Sanity check that no callbacks are dangling
 973                 $fnames = $this->pendingWriteAndCallbackCallers();
 974                 if ( $fnames ) {
 975                         throw new RuntimeException(
 976                                 "Transaction callbacks are still pending:\n" . implode( ', ', $fnames )
 977                         );
 978                 }
 979
 980                 return $closed;
 981         }
 982
 983         /**
 984          * Make sure isOpen() returns true as a sanity check
 985          *
 986          * @throws DBUnexpectedError
 987          */
 988         protected function assertOpen() {
 989                 if ( !$this->isOpen() ) {
 990                         throw new DBUnexpectedError( $this, "DB connection was already closed." );
 991                 }
 992         }
 993
 994         /**
 995          * Closes underlying database connection
 996          * @since 1.20
 997          * @return bool Whether connection was closed successfully
 998          */
 999         abstract protected function closeConnection();
1000
1001         /**
1002          * @deprecated since 1.32
1003          * @param string $error Fallback message, if none is given by DB
1004          * @throws DBConnectionError
1005          */
1006         public function reportConnectionError( $error = 'Unknown error' ) {
1007                 call_user_func( $this->deprecationLogger, 'Use of ' . __METHOD__ . ' is deprecated.' );
1008                 throw new DBConnectionError( $this, $this->lastError() ?: $error );
1009         }
1010
1011         /**
1012          * Run a query and return a DBMS-dependent wrapper (that has all IResultWrapper methods)
1013          *
1014          * This might return things, such as mysqli_result, that do not formally implement
1015          * IResultWrapper, but nonetheless implement all of its methods correctly
1016          *
1017          * @param string $sql SQL query.
1018          * @return IResultWrapper|bool Iterator to feed to fetchObject/fetchRow; false on failure
1019          */
1020         abstract protected function doQuery( $sql );
1021
1022         /**
1023          * Determine whether a query writes to the DB. When in doubt, this returns true.
1024          *
1025          * Main use cases:
1026          *
1027          * - Subsequent web requests should not need to wait for replication from
1028          *   the master position seen by this web request, unless this request made
1029          *   changes to the master. This is handled by ChronologyProtector by checking
1030          *   doneWrites() at the end of the request. doneWrites() returns true if any
1031          *   query set lastWriteTime; which query() does based on isWriteQuery().
1032          *
1033          * - Reject write queries to replica DBs, in query().
1034          *
1035          * @param string $sql
1036          * @return bool
1037          */
1038         protected function isWriteQuery( $sql ) {
1039                 // BEGIN and COMMIT queries are considered read queries here.
1040                 // Database backends and drivers (MySQL, MariaDB, php-mysqli) generally
1041                 // treat these as write queries, in that their results have "affected rows"
1042                 // as meta data as from writes, instead of "num rows" as from reads.
1043                 // But, we treat them as read queries because when reading data (from
1044                 // either replica or master) we use transactions to enable repeatable-read
1045                 // snapshots, which ensures we get consistent results from the same snapshot
1046                 // for all queries within a request. Use cases:
1047                 // - Treating these as writes would trigger ChronologyProtector (see method doc).
1048                 // - We use this method to reject writes to replicas, but we need to allow
1049                 //   use of transactions on replicas for read snapshots. This fine given
1050                 //   that transactions by themselves don't make changes, only actual writes
1051                 //   within the transaction matter, which we still detect.
1052                 return !preg_match(
1053                         '/^(?:SELECT|BEGIN|ROLLBACK|COMMIT|SET|SHOW|EXPLAIN|\(SELECT)\b/i', $sql );
1054         }
1055
1056         /**
1057          * @param string $sql
1058          * @return string|null
1059          */
1060         protected function getQueryVerb( $sql ) {
1061                 return preg_match( '/^\s*([a-z]+)/i', $sql, $m ) ? strtoupper( $m[1] ) : null;
1062         }
1063
1064         /**
1065          * Determine whether a SQL statement is sensitive to isolation level.
1066          *
1067          * A SQL statement is considered transactable if its result could vary
1068          * depending on the transaction isolation level. Operational commands
1069          * such as 'SET' and 'SHOW' are not considered to be transactable.
1070          *
1071          * Main purpose: Used by query() to decide whether to begin a transaction
1072          * before the current query (in DBO_TRX mode, on by default).
1073          *
1074          * @param string $sql
1075          * @return bool
1076          */
1077         protected function isTransactableQuery( $sql ) {
1078                 return !in_array(
1079                         $this->getQueryVerb( $sql ),
1080                         [ 'BEGIN', 'ROLLBACK', 'COMMIT', 'SET', 'SHOW', 'CREATE', 'ALTER' ],
1081                         true
1082                 );
1083         }
1084
1085         /**
1086          * @param string $sql A SQL query
1087          * @return bool Whether $sql is SQL for TEMPORARY table operation
1088          */
1089         protected function registerTempTableOperation( $sql ) {
1090                 if ( preg_match(
1091                         '/^CREATE\s+TEMPORARY\s+TABLE\s+(?:IF\s+NOT\s+EXISTS\s+)?[`"\']?(\w+)[`"\']?/i',
1092                         $sql,
1093                         $matches
1094                 ) ) {
1095                         $this->sessionTempTables[$matches[1]] = 1;
1096
1097                         return true;
1098                 } elseif ( preg_match(
1099                         '/^DROP\s+(?:TEMPORARY\s+)?TABLE\s+(?:IF\s+EXISTS\s+)?[`"\']?(\w+)[`"\']?/i',
1100                         $sql,
1101                         $matches
1102                 ) ) {
1103                         $isTemp = isset( $this->sessionTempTables[$matches[1]] );
1104                         unset( $this->sessionTempTables[$matches[1]] );
1105
1106                         return $isTemp;
1107                 } elseif ( preg_match(
1108                         '/^TRUNCATE\s+(?:TEMPORARY\s+)?TABLE\s+(?:IF\s+EXISTS\s+)?[`"\']?(\w+)[`"\']?/i',
1109                         $sql,
1110                         $matches
1111                 ) ) {
1112                         return isset( $this->sessionTempTables[$matches[1]] );
1113                 } elseif ( preg_match(
1114                         '/^(?:INSERT\s+(?:\w+\s+)?INTO|UPDATE|DELETE\s+FROM)\s+[`"\']?(\w+)[`"\']?/i',
1115                         $sql,
1116                         $matches
1117                 ) ) {
1118                         return isset( $this->sessionTempTables[$matches[1]] );
1119                 }
1120
1121                 return false;
1122         }
1123
1124         public function query( $sql, $fname = __METHOD__, $tempIgnore = false ) {
1125                 $this->assertTransactionStatus( $sql, $fname );
1126
1127                 # Avoid fatals if close() was called
1128                 $this->assertOpen();
1129
1130                 $priorWritesPending = $this->writesOrCallbacksPending();
1131                 $this->lastQuery = $sql;
1132
1133                 $isWrite = $this->isWriteQuery( $sql );
1134                 if ( $isWrite ) {
1135                         $isNonTempWrite = !$this->registerTempTableOperation( $sql );
1136                 } else {
1137                         $isNonTempWrite = false;
1138                 }
1139
1140                 if ( $isWrite ) {
1141                         if ( $this->getLBInfo( 'replica' ) === true ) {
1142                                 throw new DBError(
1143                                         $this,
1144                                         'Write operations are not allowed on replica database connections.'
1145                                 );
1146                         }
1147                         # In theory, non-persistent writes are allowed in read-only mode, but due to things
1148                         # like https://bugs.mysql.com/bug.php?id=33669 that might not work anyway...
1149                         $reason = $this->getReadOnlyReason();
1150                         if ( $reason !== false ) {
1151                                 throw new DBReadOnlyError( $this, "Database is read-only: $reason" );
1152                         }
1153                         # Set a flag indicating that writes have been done
1154                         $this->lastWriteTime = microtime( true );
1155                 }
1156
1157                 # Add trace comment to the begin of the sql string, right after the operator.
1158                 # Or, for one-word queries (like "BEGIN" or COMMIT") add it to the end (T44598)
1159                 $commentedSql = preg_replace( '/\s|$/', " /* $fname {$this->agent} */ ", $sql, 1 );
1160
1161                 # Start implicit transactions that wrap the request if DBO_TRX is enabled
1162                 if ( !$this->trxLevel && $this->getFlag( self::DBO_TRX )
1163                         && $this->isTransactableQuery( $sql )
1164                 ) {
1165                         $this->begin( __METHOD__ . " ($fname)", self::TRANSACTION_INTERNAL );
1166                         $this->trxAutomatic = true;
1167                 }
1168
1169                 # Keep track of whether the transaction has write queries pending
1170                 if ( $this->trxLevel && !$this->trxDoneWrites && $isWrite ) {
1171                         $this->trxDoneWrites = true;
1172                         $this->trxProfiler->transactionWritingIn(
1173                                 $this->server, $this->getDomainID(), $this->trxShortId );
1174                 }
1175
1176                 if ( $this->getFlag( self::DBO_DEBUG ) ) {
1177                         $this->queryLogger->debug( "{$this->getDomainID()} {$commentedSql}" );
1178                 }
1179
1180                 # Send the query to the server and fetch any corresponding errors
1181                 $ret = $this->doProfiledQuery( $sql, $commentedSql, $isNonTempWrite, $fname );
1182                 $lastError = $this->lastError();
1183                 $lastErrno = $this->lastErrno();
1184
1185                 # Try reconnecting if the connection was lost
1186                 if ( $ret === false && $this->wasConnectionLoss() ) {
1187                         # Check if any meaningful session state was lost
1188                         $recoverable = $this->canRecoverFromDisconnect( $sql, $priorWritesPending );
1189                         # Update session state tracking and try to restore the connection
1190                         $reconnected = $this->replaceLostConnection( __METHOD__ );
1191                         # Silently resend the query to the server if it is safe and possible
1192                         if ( $reconnected && $recoverable ) {
1193                                 $ret = $this->doProfiledQuery( $sql, $commentedSql, $isNonTempWrite, $fname );
1194                                 $lastError = $this->lastError();
1195                                 $lastErrno = $this->lastErrno();
1196
1197                                 if ( $ret === false && $this->wasConnectionLoss() ) {
1198                                         # Query probably causes disconnects; reconnect and do not re-run it
1199                                         $this->replaceLostConnection( __METHOD__ );
1200                                 }
1201                         }
1202                 }
1203
1204                 if ( $ret === false ) {
1205                         if ( $this->trxLevel ) {
1206                                 if ( $this->wasKnownStatementRollbackError() ) {
1207                                         # We're ignoring an error that caused just the current query to be aborted.
1208                                         # But log the cause so we can log a deprecation notice if a caller actually
1209                                         # does ignore it.
1210                                         $this->trxStatusIgnoredCause = [ $lastError, $lastErrno, $fname ];
1211                                 } else {
1212                                         # Either the query was aborted or all queries after BEGIN where aborted.
1213                                         # In the first case, the only options going forward are (a) ROLLBACK, or
1214                                         # (b) ROLLBACK TO SAVEPOINT (if one was set). If the later case, the only
1215                                         # option is ROLLBACK, since the snapshots would have been released.
1216                                         $this->trxStatus = self::STATUS_TRX_ERROR;
1217                                         $this->trxStatusCause =
1218                                                 $this->makeQueryException( $lastError, $lastErrno, $sql, $fname );
1219                                         $tempIgnore = false; // cannot recover
1220                                         $this->trxStatusIgnoredCause = null;
1221                                 }
1222                         }
1223
1224                         $this->reportQueryError( $lastError, $lastErrno, $sql, $fname, $tempIgnore );
1225                 }
1226
1227                 return $this->resultObject( $ret );
1228         }
1229
1230         /**
1231          * Wrapper for query() that also handles profiling, logging, and affected row count updates
1232          *
1233          * @param string $sql Original SQL query
1234          * @param string $commentedSql SQL query with debugging/trace comment
1235          * @param bool $isWrite Whether the query is a (non-temporary) write operation
1236          * @param string $fname Name of the calling function
1237          * @return bool|ResultWrapper True for a successful write query, ResultWrapper
1238          *     object for a successful read query, or false on failure
1239          */
1240         private function doProfiledQuery( $sql, $commentedSql, $isWrite, $fname ) {
1241                 $isMaster = !is_null( $this->getLBInfo( 'master' ) );
1242                 # generalizeSQL() will probably cut down the query to reasonable
1243                 # logging size most of the time. The substr is really just a sanity check.
1244                 if ( $isMaster ) {
1245                         $queryProf = 'query-m: ' . substr( self::generalizeSQL( $sql ), 0, 255 );
1246                 } else {
1247                         $queryProf = 'query: ' . substr( self::generalizeSQL( $sql ), 0, 255 );
1248                 }
1249
1250                 # Include query transaction state
1251                 $queryProf .= $this->trxShortId ? " [TRX#{$this->trxShortId}]" : "";
1252
1253                 $startTime = microtime( true );
1254                 if ( $this->profiler ) {
1255                         $this->profiler->profileIn( $queryProf );
1256                 }
1257                 $this->affectedRowCount = null;
1258                 $ret = $this->doQuery( $commentedSql );
1259                 $this->affectedRowCount = $this->affectedRows();
1260                 if ( $this->profiler ) {
1261                         $this->profiler->profileOut( $queryProf );
1262                 }
1263                 $queryRuntime = max( microtime( true ) - $startTime, 0.0 );
1264
1265                 unset( $queryProfSection ); // profile out (if set)
1266
1267                 if ( $ret !== false ) {
1268                         $this->lastPing = $startTime;
1269                         if ( $isWrite && $this->trxLevel ) {
1270                                 $this->updateTrxWriteQueryTime( $sql, $queryRuntime, $this->affectedRows() );
1271                                 $this->trxWriteCallers[] = $fname;
1272                         }
1273                 }
1274
1275                 if ( $sql === self::PING_QUERY ) {
1276                         $this->rttEstimate = $queryRuntime;
1277                 }
1278
1279                 $this->trxProfiler->recordQueryCompletion(
1280                         $queryProf,
1281                         $startTime,
1282                         $isWrite,
1283                         $isWrite ? $this->affectedRows() : $this->numRows( $ret )
1284                 );
1285                 $this->queryLogger->debug( $sql, [
1286                         'method' => $fname,
1287                         'master' => $isMaster,
1288                         'runtime' => $queryRuntime,
1289                 ] );
1290
1291                 return $ret;
1292         }
1293
1294         /**
1295          * Update the estimated run-time of a query, not counting large row lock times
1296          *
1297          * LoadBalancer can be set to rollback transactions that will create huge replication
1298          * lag. It bases this estimate off of pendingWriteQueryDuration(). Certain simple
1299          * queries, like inserting a row can take a long time due to row locking. This method
1300          * uses some simple heuristics to discount those cases.
1301          *
1302          * @param string $sql A SQL write query
1303          * @param float $runtime Total runtime, including RTT
1304          * @param int $affected Affected row count
1305          */
1306         private function updateTrxWriteQueryTime( $sql, $runtime, $affected ) {
1307                 // Whether this is indicative of replica DB runtime (except for RBR or ws_repl)
1308                 $indicativeOfReplicaRuntime = true;
1309                 if ( $runtime > self::SLOW_WRITE_SEC ) {
1310                         $verb = $this->getQueryVerb( $sql );
1311                         // insert(), upsert(), replace() are fast unless bulky in size or blocked on locks
1312                         if ( $verb === 'INSERT' ) {
1313                                 $indicativeOfReplicaRuntime = $this->affectedRows() > self::SMALL_WRITE_ROWS;
1314                         } elseif ( $verb === 'REPLACE' ) {
1315                                 $indicativeOfReplicaRuntime = $this->affectedRows() > self::SMALL_WRITE_ROWS / 2;
1316                         }
1317                 }
1318
1319                 $this->trxWriteDuration += $runtime;
1320                 $this->trxWriteQueryCount += 1;
1321                 $this->trxWriteAffectedRows += $affected;
1322                 if ( $indicativeOfReplicaRuntime ) {
1323                         $this->trxWriteAdjDuration += $runtime;
1324                         $this->trxWriteAdjQueryCount += 1;
1325                 }
1326         }
1327
1328         /**
1329          * @param string $sql
1330          * @param string $fname
1331          * @throws DBTransactionStateError
1332          */
1333         private function assertTransactionStatus( $sql, $fname ) {
1334                 if ( $this->getQueryVerb( $sql ) === 'ROLLBACK' ) { // transaction/savepoint
1335                         return;
1336                 }
1337
1338                 if ( $this->trxStatus < self::STATUS_TRX_OK ) {
1339                         throw new DBTransactionStateError(
1340                                 $this,
1341                                 "Cannot execute query from $fname while transaction status is ERROR.",
1342                                 [],
1343                                 $this->trxStatusCause
1344                         );
1345                 } elseif ( $this->trxStatus === self::STATUS_TRX_OK && $this->trxStatusIgnoredCause ) {
1346                         list( $iLastError, $iLastErrno, $iFname ) = $this->trxStatusIgnoredCause;
1347                         call_user_func( $this->deprecationLogger,
1348                                 "Caller from $fname ignored an error originally raised from $iFname: " .
1349                                 "[$iLastErrno] $iLastError"
1350                         );
1351                         $this->trxStatusIgnoredCause = null;
1352                 }
1353         }
1354
1355         /**
1356          * Determine whether or not it is safe to retry queries after a database
1357          * connection is lost
1358          *
1359          * @param string $sql SQL query
1360          * @param bool $priorWritesPending Whether there is a transaction open with
1361          *     possible write queries or transaction pre-commit/idle callbacks
1362          *     waiting on it to finish.
1363          * @return bool True if it is safe to retry the query, false otherwise
1364          */
1365         private function canRecoverFromDisconnect( $sql, $priorWritesPending ) {
1366                 # Transaction dropped; this can mean lost writes, or REPEATABLE-READ snapshots.
1367                 # Dropped connections also mean that named locks are automatically released.
1368                 # Only allow error suppression in autocommit mode or when the lost transaction
1369                 # didn't matter anyway (aside from DBO_TRX snapshot loss).
1370                 if ( $this->namedLocksHeld ) {
1371                         return false; // possible critical section violation
1372                 } elseif ( $this->sessionTempTables ) {
1373                         return false; // tables might be queried latter
1374                 } elseif ( $sql === 'COMMIT' ) {
1375                         return !$priorWritesPending; // nothing written anyway? (T127428)
1376                 } elseif ( $sql === 'ROLLBACK' ) {
1377                         return true; // transaction lost...which is also what was requested :)
1378                 } elseif ( $this->explicitTrxActive() ) {
1379                         return false; // don't drop atomocity and explicit snapshots
1380                 } elseif ( $priorWritesPending ) {
1381                         return false; // prior writes lost from implicit transaction
1382                 }
1383
1384                 return true;
1385         }
1386
1387         /**
1388          * Clean things up after session (and thus transaction) loss
1389          */
1390         private function handleSessionLoss() {
1391                 // Clean up tracking of session-level things...
1392                 // https://dev.mysql.com/doc/refman/5.7/en/implicit-commit.html
1393                 // https://www.postgresql.org/docs/9.2/static/sql-createtable.html (ignoring ON COMMIT)
1394                 $this->sessionTempTables = [];
1395                 // https://dev.mysql.com/doc/refman/5.7/en/miscellaneous-functions.html#function_get-lock
1396                 // https://www.postgresql.org/docs/9.4/static/functions-admin.html#FUNCTIONS-ADVISORY-LOCKS
1397                 $this->namedLocksHeld = [];
1398                 // Session loss implies transaction loss
1399                 $this->handleTransactionLoss();
1400         }
1401
1402         /**
1403          * Clean things up after transaction loss
1404          */
1405         private function handleTransactionLoss() {
1406                 $this->trxLevel = 0;
1407                 $this->trxAtomicCounter = 0;
1408                 $this->trxIdleCallbacks = []; // T67263; transaction already lost
1409                 $this->trxPreCommitCallbacks = []; // T67263; transaction already lost
1410                 try {
1411                         // Handle callbacks in trxEndCallbacks, e.g. onTransactionResolution().
1412                         // If callback suppression is set then the array will remain unhandled.
1413                         $this->runOnTransactionIdleCallbacks( self::TRIGGER_ROLLBACK );
1414                 } catch ( Exception $ex ) {
1415                         // Already logged; move on...
1416                 }
1417                 try {
1418                         // Handle callbacks in trxRecurringCallbacks, e.g. setTransactionListener()
1419                         $this->runTransactionListenerCallbacks( self::TRIGGER_ROLLBACK );
1420                 } catch ( Exception $ex ) {
1421                         // Already logged; move on...
1422                 }
1423         }
1424
1425         /**
1426          * Checks whether the cause of the error is detected to be a timeout.
1427          *
1428          * It returns false by default, and not all engines support detecting this yet.
1429          * If this returns false, it will be treated as a generic query error.
1430          *
1431          * @param string $error Error text
1432          * @param int $errno Error number
1433          * @return bool
1434          */
1435         protected function wasQueryTimeout( $error, $errno ) {
1436                 return false;
1437         }
1438
1439         /**
1440          * Report a query error. Log the error, and if neither the object ignore
1441          * flag nor the $tempIgnore flag is set, throw a DBQueryError.
1442          *
1443          * @param string $error
1444          * @param int $errno
1445          * @param string $sql
1446          * @param string $fname
1447          * @param bool $tempIgnore
1448          * @throws DBQueryError
1449          */
1450         public function reportQueryError( $error, $errno, $sql, $fname, $tempIgnore = false ) {
1451                 if ( $tempIgnore ) {
1452                         $this->queryLogger->debug( "SQL ERROR (ignored): $error\n" );
1453                 } else {
1454                         $exception = $this->makeQueryException( $error, $errno, $sql, $fname );
1455
1456                         throw $exception;
1457                 }
1458         }
1459
1460         /**
1461          * @param string $error
1462          * @param string|int $errno
1463          * @param string $sql
1464          * @param string $fname
1465          * @return DBError
1466          */
1467         private function makeQueryException( $error, $errno, $sql, $fname ) {
1468                 $sql1line = mb_substr( str_replace( "\n", "\\n", $sql ), 0, 5 * 1024 );
1469                 $this->queryLogger->error(
1470                         "{fname}\t{db_server}\t{errno}\t{error}\t{sql1line}",
1471                         $this->getLogContext( [
1472                                 'method' => __METHOD__,
1473                                 'errno' => $errno,
1474                                 'error' => $error,
1475                                 'sql1line' => $sql1line,
1476                                 'fname' => $fname,
1477                         ] )
1478                 );
1479                 $this->queryLogger->debug( "SQL ERROR: " . $error . "\n" );
1480                 $wasQueryTimeout = $this->wasQueryTimeout( $error, $errno );
1481                 if ( $wasQueryTimeout ) {
1482                         $e = new DBQueryTimeoutError( $this, $error, $errno, $sql, $fname );
1483                 } else {
1484                         $e = new DBQueryError( $this, $error, $errno, $sql, $fname );
1485                 }
1486
1487                 return $e;
1488         }
1489
1490         public function freeResult( $res ) {
1491         }
1492
1493         public function selectField(
1494                 $table, $var, $cond = '', $fname = __METHOD__, $options = [], $join_conds = []
1495         ) {
1496                 if ( $var === '*' ) { // sanity
1497                         throw new DBUnexpectedError( $this, "Cannot use a * field: got '$var'" );
1498                 }
1499
1500                 if ( !is_array( $options ) ) {
1501                         $options = [ $options ];
1502                 }
1503
1504                 $options['LIMIT'] = 1;
1505
1506                 $res = $this->select( $table, $var, $cond, $fname, $options, $join_conds );
1507                 if ( $res === false || !$this->numRows( $res ) ) {
1508                         return false;
1509                 }
1510
1511                 $row = $this->fetchRow( $res );
1512
1513                 if ( $row !== false ) {
1514                         return reset( $row );
1515                 } else {
1516                         return false;
1517                 }
1518         }
1519
1520         public function selectFieldValues(
1521                 $table, $var, $cond = '', $fname = __METHOD__, $options = [], $join_conds = []
1522         ) {
1523                 if ( $var === '*' ) { // sanity
1524                         throw new DBUnexpectedError( $this, "Cannot use a * field" );
1525                 } elseif ( !is_string( $var ) ) { // sanity
1526                         throw new DBUnexpectedError( $this, "Cannot use an array of fields" );
1527                 }
1528
1529                 if ( !is_array( $options ) ) {
1530                         $options = [ $options ];
1531                 }
1532
1533                 $res = $this->select( $table, $var, $cond, $fname, $options, $join_conds );
1534                 if ( $res === false ) {
1535                         return false;
1536                 }
1537
1538                 $values = [];
1539                 foreach ( $res as $row ) {
1540                         $values[] = $row->$var;
1541                 }
1542
1543                 return $values;
1544         }
1545
1546         /**
1547          * Returns an optional USE INDEX clause to go after the table, and a
1548          * string to go at the end of the query.
1549          *
1550          * @param array $options Associative array of options to be turned into
1551          *   an SQL query, valid keys are listed in the function.
1552          * @return array
1553          * @see Database::select()
1554          */
1555         protected function makeSelectOptions( $options ) {
1556                 $preLimitTail = $postLimitTail = '';
1557                 $startOpts = '';
1558
1559                 $noKeyOptions = [];
1560
1561                 foreach ( $options as $key => $option ) {
1562                         if ( is_numeric( $key ) ) {
1563                                 $noKeyOptions[$option] = true;
1564                         }
1565                 }
1566
1567                 $preLimitTail .= $this->makeGroupByWithHaving( $options );
1568
1569                 $preLimitTail .= $this->makeOrderBy( $options );
1570
1571                 if ( isset( $noKeyOptions['FOR UPDATE'] ) ) {
1572                         $postLimitTail .= ' FOR UPDATE';
1573                 }
1574
1575                 if ( isset( $noKeyOptions['LOCK IN SHARE MODE'] ) ) {
1576                         $postLimitTail .= ' LOCK IN SHARE MODE';
1577                 }
1578
1579                 if ( isset( $noKeyOptions['DISTINCT'] ) || isset( $noKeyOptions['DISTINCTROW'] ) ) {
1580                         $startOpts .= 'DISTINCT';
1581                 }
1582
1583                 # Various MySQL extensions
1584                 if ( isset( $noKeyOptions['STRAIGHT_JOIN'] ) ) {
1585                         $startOpts .= ' /*! STRAIGHT_JOIN */';
1586                 }
1587
1588                 if ( isset( $noKeyOptions['HIGH_PRIORITY'] ) ) {
1589                         $startOpts .= ' HIGH_PRIORITY';
1590                 }
1591
1592                 if ( isset( $noKeyOptions['SQL_BIG_RESULT'] ) ) {
1593                         $startOpts .= ' SQL_BIG_RESULT';
1594                 }
1595
1596                 if ( isset( $noKeyOptions['SQL_BUFFER_RESULT'] ) ) {
1597                         $startOpts .= ' SQL_BUFFER_RESULT';
1598                 }
1599
1600                 if ( isset( $noKeyOptions['SQL_SMALL_RESULT'] ) ) {
1601                         $startOpts .= ' SQL_SMALL_RESULT';
1602                 }
1603
1604                 if ( isset( $noKeyOptions['SQL_CALC_FOUND_ROWS'] ) ) {
1605                         $startOpts .= ' SQL_CALC_FOUND_ROWS';
1606                 }
1607
1608                 if ( isset( $noKeyOptions['SQL_CACHE'] ) ) {
1609                         $startOpts .= ' SQL_CACHE';
1610                 }
1611
1612                 if ( isset( $noKeyOptions['SQL_NO_CACHE'] ) ) {
1613                         $startOpts .= ' SQL_NO_CACHE';
1614                 }
1615
1616                 if ( isset( $options['USE INDEX'] ) && is_string( $options['USE INDEX'] ) ) {
1617                         $useIndex = $this->useIndexClause( $options['USE INDEX'] );
1618                 } else {
1619                         $useIndex = '';
1620                 }
1621                 if ( isset( $options['IGNORE INDEX'] ) && is_string( $options['IGNORE INDEX'] ) ) {
1622                         $ignoreIndex = $this->ignoreIndexClause( $options['IGNORE INDEX'] );
1623                 } else {
1624                         $ignoreIndex = '';
1625                 }
1626
1627                 return [ $startOpts, $useIndex, $preLimitTail, $postLimitTail, $ignoreIndex ];
1628         }
1629
1630         /**
1631          * Returns an optional GROUP BY with an optional HAVING
1632          *
1633          * @param array $options Associative array of options
1634          * @return string
1635          * @see Database::select()
1636          * @since 1.21
1637          */
1638         protected function makeGroupByWithHaving( $options ) {
1639                 $sql = '';
1640                 if ( isset( $options['GROUP BY'] ) ) {
1641                         $gb = is_array( $options['GROUP BY'] )
1642                                 ? implode( ',', $options['GROUP BY'] )
1643                                 : $options['GROUP BY'];
1644                         $sql .= ' GROUP BY ' . $gb;
1645                 }
1646                 if ( isset( $options['HAVING'] ) ) {
1647                         $having = is_array( $options['HAVING'] )
1648                                 ? $this->makeList( $options['HAVING'], self::LIST_AND )
1649                                 : $options['HAVING'];
1650                         $sql .= ' HAVING ' . $having;
1651                 }
1652
1653                 return $sql;
1654         }
1655
1656         /**
1657          * Returns an optional ORDER BY
1658          *
1659          * @param array $options Associative array of options
1660          * @return string
1661          * @see Database::select()
1662          * @since 1.21
1663          */
1664         protected function makeOrderBy( $options ) {
1665                 if ( isset( $options['ORDER BY'] ) ) {
1666                         $ob = is_array( $options['ORDER BY'] )
1667                                 ? implode( ',', $options['ORDER BY'] )
1668                                 : $options['ORDER BY'];
1669
1670                         return ' ORDER BY ' . $ob;
1671                 }
1672
1673                 return '';
1674         }
1675
1676         public function select(
1677                 $table, $vars, $conds = '', $fname = __METHOD__, $options = [], $join_conds = []
1678         ) {
1679                 $sql = $this->selectSQLText( $table, $vars, $conds, $fname, $options, $join_conds );
1680
1681                 return $this->query( $sql, $fname );
1682         }
1683
1684         public function selectSQLText( $table, $vars, $conds = '', $fname = __METHOD__,
1685                 $options = [], $join_conds = []
1686         ) {
1687                 if ( is_array( $vars ) ) {
1688                         $fields = implode( ',', $this->fieldNamesWithAlias( $vars ) );
1689                 } else {
1690                         $fields = $vars;
1691                 }
1692
1693                 $options = (array)$options;
1694                 $useIndexes = ( isset( $options['USE INDEX'] ) && is_array( $options['USE INDEX'] ) )
1695                         ? $options['USE INDEX']
1696                         : [];
1697                 $ignoreIndexes = (
1698                         isset( $options['IGNORE INDEX'] ) &&
1699                         is_array( $options['IGNORE INDEX'] )
1700                 )
1701                         ? $options['IGNORE INDEX']
1702                         : [];
1703
1704                 if (
1705                         $this->selectOptionsIncludeLocking( $options ) &&
1706                         $this->selectFieldsOrOptionsAggregate( $vars, $options )
1707                 ) {
1708                         // Some DB types (postgres/oracle) disallow FOR UPDATE with aggregate
1709                         // functions. Discourage use of such queries to encourage compatibility.
1710                         call_user_func(
1711                                 $this->deprecationLogger,
1712                                 __METHOD__ . ": aggregation used with a locking SELECT ($fname)."
1713                         );
1714                 }
1715
1716                 if ( is_array( $table ) ) {
1717                         $from = ' FROM ' .
1718                                 $this->tableNamesWithIndexClauseOrJOIN(
1719                                         $table, $useIndexes, $ignoreIndexes, $join_conds );
1720                 } elseif ( $table != '' ) {
1721                         $from = ' FROM ' .
1722                                 $this->tableNamesWithIndexClauseOrJOIN(
1723                                         [ $table ], $useIndexes, $ignoreIndexes, [] );
1724                 } else {
1725                         $from = '';
1726                 }
1727
1728                 list( $startOpts, $useIndex, $preLimitTail, $postLimitTail, $ignoreIndex ) =
1729                         $this->makeSelectOptions( $options );
1730
1731                 if ( is_array( $conds ) ) {
1732                         $conds = $this->makeList( $conds, self::LIST_AND );
1733                 }
1734
1735                 if ( $conds === null || $conds === false ) {
1736                         $this->queryLogger->warning(
1737                                 __METHOD__
1738                                 . ' called from '
1739                                 . $fname
1740                                 . ' with incorrect parameters: $conds must be a string or an array'
1741                         );
1742                         $conds = '';
1743                 }
1744
1745                 if ( $conds === '' ) {
1746                         $sql = "SELECT $startOpts $fields $from $useIndex $ignoreIndex $preLimitTail";
1747                 } elseif ( is_string( $conds ) ) {
1748                         $sql = "SELECT $startOpts $fields $from $useIndex $ignoreIndex " .
1749                                 "WHERE $conds $preLimitTail";
1750                 } else {
1751                         throw new DBUnexpectedError( $this, __METHOD__ . ' called with incorrect parameters' );
1752                 }
1753
1754                 if ( isset( $options['LIMIT'] ) ) {
1755                         $sql = $this->limitResult( $sql, $options['LIMIT'],
1756                                 $options['OFFSET'] ?? false );
1757                 }
1758                 $sql = "$sql $postLimitTail";
1759
1760                 if ( isset( $options['EXPLAIN'] ) ) {
1761                         $sql = 'EXPLAIN ' . $sql;
1762                 }
1763
1764                 return $sql;
1765         }
1766
1767         public function selectRow( $table, $vars, $conds, $fname = __METHOD__,
1768                 $options = [], $join_conds = []
1769         ) {
1770                 $options = (array)$options;
1771                 $options['LIMIT'] = 1;
1772                 $res = $this->select( $table, $vars, $conds, $fname, $options, $join_conds );
1773
1774                 if ( $res === false ) {
1775                         return false;
1776                 }
1777
1778                 if ( !$this->numRows( $res ) ) {
1779                         return false;
1780                 }
1781
1782                 $obj = $this->fetchObject( $res );
1783
1784                 return $obj;
1785         }
1786
1787         public function estimateRowCount(
1788                 $table, $var = '*', $conds = '', $fname = __METHOD__, $options = [], $join_conds = []
1789         ) {
1790                 $conds = $this->normalizeConditions( $conds, $fname );
1791                 $column = $this->extractSingleFieldFromList( $var );
1792                 if ( is_string( $column ) && !in_array( $column, [ '*', '1' ] ) ) {
1793                         $conds[] = "$column IS NOT NULL";
1794                 }
1795
1796                 $res = $this->select(
1797                         $table, [ 'rowcount' => 'COUNT(*)' ], $conds, $fname, $options, $join_conds
1798                 );
1799                 $row = $res ? $this->fetchRow( $res ) : [];
1800
1801                 return isset( $row['rowcount'] ) ? (int)$row['rowcount'] : 0;
1802         }
1803
1804         public function selectRowCount(
1805                 $tables, $var = '*', $conds = '', $fname = __METHOD__, $options = [], $join_conds = []
1806         ) {
1807                 $conds = $this->normalizeConditions( $conds, $fname );
1808                 $column = $this->extractSingleFieldFromList( $var );
1809                 if ( is_string( $column ) && !in_array( $column, [ '*', '1' ] ) ) {
1810                         $conds[] = "$column IS NOT NULL";
1811                 }
1812
1813                 $res = $this->select(
1814                         [
1815                                 'tmp_count' => $this->buildSelectSubquery(
1816                                         $tables,
1817                                         '1',
1818                                         $conds,
1819                                         $fname,
1820                                         $options,
1821                                         $join_conds
1822                                 )
1823                         ],
1824                         [ 'rowcount' => 'COUNT(*)' ],
1825                         [],
1826                         $fname
1827                 );
1828                 $row = $res ? $this->fetchRow( $res ) : [];
1829
1830                 return isset( $row['rowcount'] ) ? (int)$row['rowcount'] : 0;
1831         }
1832
1833         /**
1834          * @param string|array $options
1835          * @return bool
1836          */
1837         private function selectOptionsIncludeLocking( $options ) {
1838                 $options = (array)$options;
1839                 foreach ( [ 'FOR UPDATE', 'LOCK IN SHARE MODE' ] as $lock ) {
1840                         if ( in_array( $lock, $options, true ) ) {
1841                                 return true;
1842                         }
1843                 }
1844
1845                 return false;
1846         }
1847
1848         /**
1849          * @param array|string $fields
1850          * @param array|string $options
1851          * @return bool
1852          */
1853         private function selectFieldsOrOptionsAggregate( $fields, $options ) {
1854                 foreach ( (array)$options as $key => $value ) {
1855                         if ( is_string( $key ) ) {
1856                                 if ( preg_match( '/^(?:GROUP BY|HAVING)$/i', $key ) ) {
1857                                         return true;
1858                                 }
1859                         } elseif ( is_string( $value ) ) {
1860                                 if ( preg_match( '/^(?:DISTINCT|DISTINCTROW)$/i', $value ) ) {
1861                                         return true;
1862                                 }
1863                         }
1864                 }
1865
1866                 $regex = '/^(?:COUNT|MIN|MAX|SUM|GROUP_CONCAT|LISTAGG|ARRAY_AGG)\s*\\(/i';
1867                 foreach ( (array)$fields as $field ) {
1868                         if ( is_string( $field ) && preg_match( $regex, $field ) ) {
1869                                 return true;
1870                         }
1871                 }
1872
1873                 return false;
1874         }
1875
1876         /**
1877          * @param array|string $conds
1878          * @param string $fname
1879          * @return array
1880          */
1881         final protected function normalizeConditions( $conds, $fname ) {
1882                 if ( $conds === null || $conds === false ) {
1883                         $this->queryLogger->warning(
1884                                 __METHOD__
1885                                 . ' called from '
1886                                 . $fname
1887                                 . ' with incorrect parameters: $conds must be a string or an array'
1888                         );
1889                         $conds = '';
1890                 }
1891
1892                 if ( !is_array( $conds ) ) {
1893                         $conds = ( $conds === '' ) ? [] : [ $conds ];
1894                 }
1895
1896                 return $conds;
1897         }
1898
1899         /**
1900          * @param array|string $var Field parameter in the style of select()
1901          * @return string|null Column name or null; ignores aliases
1902          * @throws DBUnexpectedError Errors out if multiple columns are given
1903          */
1904         final protected function extractSingleFieldFromList( $var ) {
1905                 if ( is_array( $var ) ) {
1906                         if ( !$var ) {
1907                                 $column = null;
1908                         } elseif ( count( $var ) == 1 ) {
1909                                 $column = $var[0] ?? reset( $var );
1910                         } else {
1911                                 throw new DBUnexpectedError( $this, __METHOD__ . ': got multiple columns.' );
1912                         }
1913                 } else {
1914                         $column = $var;
1915                 }
1916
1917                 return $column;
1918         }
1919
1920         public function lockForUpdate(
1921                 $table, $conds = '', $fname = __METHOD__, $options = [], $join_conds = []
1922         ) {
1923                 if ( !$this->trxLevel && !$this->getFlag( self::DBO_TRX ) ) {
1924                         throw new DBUnexpectedError(
1925                                 $this,
1926                                 __METHOD__ . ': no transaction is active nor is DBO_TRX set'
1927                         );
1928                 }
1929
1930                 $options = (array)$options;
1931                 $options[] = 'FOR UPDATE';
1932
1933                 return $this->selectRowCount( $table, '*', $conds, $fname, $options, $join_conds );
1934         }
1935
1936         /**
1937          * Removes most variables from an SQL query and replaces them with X or N for numbers.
1938          * It's only slightly flawed. Don't use for anything important.
1939          *
1940          * @param string $sql A SQL Query
1941          *
1942          * @return string
1943          */
1944         protected static function generalizeSQL( $sql ) {
1945                 # This does the same as the regexp below would do, but in such a way
1946                 # as to avoid crashing php on some large strings.
1947                 # $sql = preg_replace( "/'([^\\\\']|\\\\.)*'|\"([^\\\\\"]|\\\\.)*\"/", "'X'", $sql );
1948
1949                 $sql = str_replace( "\\\\", '', $sql );
1950                 $sql = str_replace( "\\'", '', $sql );
1951                 $sql = str_replace( "\\\"", '', $sql );
1952                 $sql = preg_replace( "/'.*'/s", "'X'", $sql );
1953                 $sql = preg_replace( '/".*"/s', "'X'", $sql );
1954
1955                 # All newlines, tabs, etc replaced by single space
1956                 $sql = preg_replace( '/\s+/', ' ', $sql );
1957
1958                 # All numbers => N,
1959                 # except the ones surrounded by characters, e.g. l10n
1960                 $sql = preg_replace( '/-?\d+(,-?\d+)+/s', 'N,...,N', $sql );
1961                 $sql = preg_replace( '/(?<![a-zA-Z])-?\d+(?![a-zA-Z])/s', 'N', $sql );
1962
1963                 return $sql;
1964         }
1965
1966         public function fieldExists( $table, $field, $fname = __METHOD__ ) {
1967                 $info = $this->fieldInfo( $table, $field );
1968
1969                 return (bool)$info;
1970         }
1971
1972         public function indexExists( $table, $index, $fname = __METHOD__ ) {
1973                 if ( !$this->tableExists( $table ) ) {
1974                         return null;
1975                 }
1976
1977                 $info = $this->indexInfo( $table, $index, $fname );
1978                 if ( is_null( $info ) ) {
1979                         return null;
1980                 } else {
1981                         return $info !== false;
1982                 }
1983         }
1984
1985         abstract public function tableExists( $table, $fname = __METHOD__ );
1986
1987         public function indexUnique( $table, $index ) {
1988                 $indexInfo = $this->indexInfo( $table, $index );
1989
1990                 if ( !$indexInfo ) {
1991                         return null;
1992                 }
1993
1994                 return !$indexInfo[0]->Non_unique;
1995         }
1996
1997         /**
1998          * Helper for Database::insert().
1999          *
2000          * @param array $options
2001          * @return string
2002          */
2003         protected function makeInsertOptions( $options ) {
2004                 return implode( ' ', $options );
2005         }
2006
2007         public function insert( $table, $a, $fname = __METHOD__, $options = [] ) {
2008                 # No rows to insert, easy just return now
2009                 if ( !count( $a ) ) {
2010                         return true;
2011                 }
2012
2013                 $table = $this->tableName( $table );
2014
2015                 if ( !is_array( $options ) ) {
2016                         $options = [ $options ];
2017                 }
2018
2019                 $fh = null;
2020                 if ( isset( $options['fileHandle'] ) ) {
2021                         $fh = $options['fileHandle'];
2022                 }
2023                 $options = $this->makeInsertOptions( $options );
2024
2025                 if ( isset( $a[0] ) && is_array( $a[0] ) ) {
2026                         $multi = true;
2027                         $keys = array_keys( $a[0] );
2028                 } else {
2029                         $multi = false;
2030                         $keys = array_keys( $a );
2031                 }
2032
2033                 $sql = 'INSERT ' . $options .
2034                         " INTO $table (" . implode( ',', $keys ) . ') VALUES ';
2035
2036                 if ( $multi ) {
2037                         $first = true;
2038                         foreach ( $a as $row ) {
2039                                 if ( $first ) {
2040                                         $first = false;
2041                                 } else {
2042                                         $sql .= ',';
2043                                 }
2044                                 $sql .= '(' . $this->makeList( $row ) . ')';
2045                         }
2046                 } else {
2047                         $sql .= '(' . $this->makeList( $a ) . ')';
2048                 }
2049
2050                 if ( $fh !== null && false === fwrite( $fh, $sql ) ) {
2051                         return false;
2052                 } elseif ( $fh !== null ) {
2053                         return true;
2054                 }
2055
2056                 return (bool)$this->query( $sql, $fname );
2057         }
2058
2059         /**
2060          * Make UPDATE options array for Database::makeUpdateOptions
2061          *
2062          * @param array $options
2063          * @return array
2064          */
2065         protected function makeUpdateOptionsArray( $options ) {
2066                 if ( !is_array( $options ) ) {
2067                         $options = [ $options ];
2068                 }
2069
2070                 $opts = [];
2071
2072                 if ( in_array( 'IGNORE', $options ) ) {
2073                         $opts[] = 'IGNORE';
2074                 }
2075
2076                 return $opts;
2077         }
2078
2079         /**
2080          * Make UPDATE options for the Database::update function
2081          *
2082          * @param array $options The options passed to Database::update
2083          * @return string
2084          */
2085         protected function makeUpdateOptions( $options ) {
2086                 $opts = $this->makeUpdateOptionsArray( $options );
2087
2088                 return implode( ' ', $opts );
2089         }
2090
2091         public function update( $table, $values, $conds, $fname = __METHOD__, $options = [] ) {
2092                 $table = $this->tableName( $table );
2093                 $opts = $this->makeUpdateOptions( $options );
2094                 $sql = "UPDATE $opts $table SET " . $this->makeList( $values, self::LIST_SET );
2095
2096                 if ( $conds !== [] && $conds !== '*' ) {
2097                         $sql .= " WHERE " . $this->makeList( $conds, self::LIST_AND );
2098                 }
2099
2100                 return (bool)$this->query( $sql, $fname );
2101         }
2102
2103         public function makeList( $a, $mode = self::LIST_COMMA ) {
2104                 if ( !is_array( $a ) ) {
2105                         throw new DBUnexpectedError( $this, __METHOD__ . ' called with incorrect parameters' );
2106                 }
2107
2108                 $first = true;
2109                 $list = '';
2110
2111                 foreach ( $a as $field => $value ) {
2112                         if ( !$first ) {
2113                                 if ( $mode == self::LIST_AND ) {
2114                                         $list .= ' AND ';
2115                                 } elseif ( $mode == self::LIST_OR ) {
2116                                         $list .= ' OR ';
2117                                 } else {
2118                                         $list .= ',';
2119                                 }
2120                         } else {
2121                                 $first = false;
2122                         }
2123
2124                         if ( ( $mode == self::LIST_AND || $mode == self::LIST_OR ) && is_numeric( $field ) ) {
2125                                 $list .= "($value)";
2126                         } elseif ( $mode == self::LIST_SET && is_numeric( $field ) ) {
2127                                 $list .= "$value";
2128                         } elseif (
2129                                 ( $mode == self::LIST_AND || $mode == self::LIST_OR ) && is_array( $value )
2130                         ) {
2131                                 // Remove null from array to be handled separately if found
2132                                 $includeNull = false;
2133                                 foreach ( array_keys( $value, null, true ) as $nullKey ) {
2134                                         $includeNull = true;
2135                                         unset( $value[$nullKey] );
2136                                 }
2137                                 if ( count( $value ) == 0 && !$includeNull ) {
2138                                         throw new InvalidArgumentException(
2139                                                 __METHOD__ . ": empty input for field $field" );
2140                                 } elseif ( count( $value ) == 0 ) {
2141                                         // only check if $field is null
2142                                         $list .= "$field IS NULL";
2143                                 } else {
2144                                         // IN clause contains at least one valid element
2145                                         if ( $includeNull ) {
2146                                                 // Group subconditions to ensure correct precedence
2147                                                 $list .= '(';
2148                                         }
2149                                         if ( count( $value ) == 1 ) {
2150                                                 // Special-case single values, as IN isn't terribly efficient
2151                                                 // Don't necessarily assume the single key is 0; we don't
2152                                                 // enforce linear numeric ordering on other arrays here.
2153                                                 $value = array_values( $value )[0];
2154                                                 $list .= $field . " = " . $this->addQuotes( $value );
2155                                         } else {
2156                                                 $list .= $field . " IN (" . $this->makeList( $value ) . ") ";
2157                                         }
2158                                         // if null present in array, append IS NULL
2159                                         if ( $includeNull ) {
2160                                                 $list .= " OR $field IS NULL)";
2161                                         }
2162                                 }
2163                         } elseif ( $value === null ) {
2164                                 if ( $mode == self::LIST_AND || $mode == self::LIST_OR ) {
2165                                         $list .= "$field IS ";
2166                                 } elseif ( $mode == self::LIST_SET ) {
2167                                         $list .= "$field = ";
2168                                 }
2169                                 $list .= 'NULL';
2170                         } else {
2171                                 if (
2172                                         $mode == self::LIST_AND || $mode == self::LIST_OR || $mode == self::LIST_SET
2173                                 ) {
2174                                         $list .= "$field = ";
2175                                 }
2176                                 $list .= $mode == self::LIST_NAMES ? $value : $this->addQuotes( $value );
2177                         }
2178                 }
2179
2180                 return $list;
2181         }
2182
2183         public function makeWhereFrom2d( $data, $baseKey, $subKey ) {
2184                 $conds = [];
2185
2186                 foreach ( $data as $base => $sub ) {
2187                         if ( count( $sub ) ) {
2188                                 $conds[] = $this->makeList(
2189                                         [ $baseKey => $base, $subKey => array_keys( $sub ) ],
2190                                         self::LIST_AND );
2191                         }
2192                 }
2193
2194                 if ( $conds ) {
2195                         return $this->makeList( $conds, self::LIST_OR );
2196                 } else {
2197                         // Nothing to search for...
2198                         return false;
2199                 }
2200         }
2201
2202         public function aggregateValue( $valuedata, $valuename = 'value' ) {
2203                 return $valuename;
2204         }
2205
2206         public function bitNot( $field ) {
2207                 return "(~$field)";
2208         }
2209
2210         public function bitAnd( $fieldLeft, $fieldRight ) {
2211                 return "($fieldLeft & $fieldRight)";
2212         }
2213
2214         public function bitOr( $fieldLeft, $fieldRight ) {
2215                 return "($fieldLeft | $fieldRight)";
2216         }
2217
2218         public function buildConcat( $stringList ) {
2219                 return 'CONCAT(' . implode( ',', $stringList ) . ')';
2220         }
2221
2222         public function buildGroupConcatField(
2223                 $delim, $table, $field, $conds = '', $join_conds = []
2224         ) {
2225                 $fld = "GROUP_CONCAT($field SEPARATOR " . $this->addQuotes( $delim ) . ')';
2226
2227                 return '(' . $this->selectSQLText( $table, $fld, $conds, null, [], $join_conds ) . ')';
2228         }
2229
2230         public function buildSubstring( $input, $startPosition, $length = null ) {
2231                 $this->assertBuildSubstringParams( $startPosition, $length );
2232                 $functionBody = "$input FROM $startPosition";
2233                 if ( $length !== null ) {
2234                         $functionBody .= " FOR $length";
2235                 }
2236                 return 'SUBSTRING(' . $functionBody . ')';
2237         }
2238
2239         /**
2240          * Check type and bounds for parameters to self::buildSubstring()
2241          *
2242          * All supported databases have substring functions that behave the same for
2243          * positive $startPosition and non-negative $length, but behaviors differ when
2244          * given 0 or negative $startPosition or negative $length. The simplest
2245          * solution to that is to just forbid those values.
2246          *
2247          * @param int $startPosition
2248          * @param int|null $length
2249          * @since 1.31
2250          */
2251         protected function assertBuildSubstringParams( $startPosition, $length ) {
2252                 if ( !is_int( $startPosition ) || $startPosition <= 0 ) {
2253                         throw new InvalidArgumentException(
2254                                 '$startPosition must be a positive integer'
2255                         );
2256                 }
2257                 if ( !( is_int( $length ) && $length >= 0 || $length === null ) ) {
2258                         throw new InvalidArgumentException(
2259                                 '$length must be null or an integer greater than or equal to 0'
2260                         );
2261                 }
2262         }
2263
2264         public function buildStringCast( $field ) {
2265                 return $field;
2266         }
2267
2268         public function buildIntegerCast( $field ) {
2269                 return 'CAST( ' . $field . ' AS INTEGER )';
2270         }
2271
2272         public function buildSelectSubquery(
2273                 $table, $vars, $conds = '', $fname = __METHOD__,
2274                 $options = [], $join_conds = []
2275         ) {
2276                 return new Subquery(
2277                         $this->selectSQLText( $table, $vars, $conds, $fname, $options, $join_conds )
2278                 );
2279         }
2280
2281         public function databasesAreIndependent() {
2282                 return false;
2283         }
2284
2285         public function selectDB( $db ) {
2286                 # Stub. Shouldn't cause serious problems if it's not overridden, but
2287                 # if your database engine supports a concept similar to MySQL's
2288                 # databases you may as well.
2289                 $this->dbName = $db;
2290
2291                 return true;
2292         }
2293
2294         public function getDBname() {
2295                 return $this->dbName;
2296         }
2297
2298         public function getServer() {
2299                 return $this->server;
2300         }
2301
2302         public function tableName( $name, $format = 'quoted' ) {
2303                 if ( $name instanceof Subquery ) {
2304                         throw new DBUnexpectedError(
2305                                 $this,
2306                                 __METHOD__ . ': got Subquery instance when expecting a string.'
2307                         );
2308                 }
2309
2310                 # Skip the entire process when we have a string quoted on both ends.
2311                 # Note that we check the end so that we will still quote any use of
2312                 # use of `database`.table. But won't break things if someone wants
2313                 # to query a database table with a dot in the name.
2314                 if ( $this->isQuotedIdentifier( $name ) ) {
2315                         return $name;
2316                 }
2317
2318                 # Lets test for any bits of text that should never show up in a table
2319                 # name. Basically anything like JOIN or ON which are actually part of
2320                 # SQL queries, but may end up inside of the table value to combine
2321                 # sql. Such as how the API is doing.
2322                 # Note that we use a whitespace test rather than a \b test to avoid
2323                 # any remote case where a word like on may be inside of a table name
2324                 # surrounded by symbols which may be considered word breaks.
2325                 if ( preg_match( '/(^|\s)(DISTINCT|JOIN|ON|AS)(\s|$)/i', $name ) !== 0 ) {
2326                         $this->queryLogger->warning(
2327                                 __METHOD__ . ": use of subqueries is not supported this way.",
2328                                 [ 'trace' => ( new RuntimeException() )->getTraceAsString() ]
2329                         );
2330
2331                         return $name;
2332                 }
2333
2334                 # Split database and table into proper variables.
2335                 list( $database, $schema, $prefix, $table ) = $this->qualifiedTableComponents( $name );
2336
2337                 # Quote $table and apply the prefix if not quoted.
2338                 # $tableName might be empty if this is called from Database::replaceVars()
2339                 $tableName = "{$prefix}{$table}";
2340                 if ( $format === 'quoted'
2341                         && !$this->isQuotedIdentifier( $tableName )
2342                         && $tableName !== ''
2343                 ) {
2344                         $tableName = $this->addIdentifierQuotes( $tableName );
2345                 }
2346
2347                 # Quote $schema and $database and merge them with the table name if needed
2348                 $tableName = $this->prependDatabaseOrSchema( $schema, $tableName, $format );
2349                 $tableName = $this->prependDatabaseOrSchema( $database, $tableName, $format );
2350
2351                 return $tableName;
2352         }
2353
2354         /**
2355          * Get the table components needed for a query given the currently selected database
2356          *
2357          * @param string $name Table name in the form of db.schema.table, db.table, or table
2358          * @return array (DB name or "" for default, schema name, table prefix, table name)
2359          */
2360         protected function qualifiedTableComponents( $name ) {
2361                 # We reverse the explode so that database.table and table both output the correct table.
2362                 $dbDetails = explode( '.', $name, 3 );
2363                 if ( count( $dbDetails ) == 3 ) {
2364                         list( $database, $schema, $table ) = $dbDetails;
2365                         # We don't want any prefix added in this case
2366                         $prefix = '';
2367                 } elseif ( count( $dbDetails ) == 2 ) {
2368                         list( $database, $table ) = $dbDetails;
2369                         # We don't want any prefix added in this case
2370                         $prefix = '';
2371                         # In dbs that support it, $database may actually be the schema
2372                         # but that doesn't affect any of the functionality here
2373                         $schema = '';
2374                 } else {
2375                         list( $table ) = $dbDetails;
2376                         if ( isset( $this->tableAliases[$table] ) ) {
2377                                 $database = $this->tableAliases[$table]['dbname'];
2378                                 $schema = is_string( $this->tableAliases[$table]['schema'] )
2379                                         ? $this->tableAliases[$table]['schema']
2380                                         : $this->schema;
2381                                 $prefix = is_string( $this->tableAliases[$table]['prefix'] )
2382                                         ? $this->tableAliases[$table]['prefix']
2383                                         : $this->tablePrefix;
2384                         } else {
2385                                 $database = '';
2386                                 $schema = $this->schema; # Default schema
2387                                 $prefix = $this->tablePrefix; # Default prefix
2388                         }
2389                 }
2390
2391                 return [ $database, $schema, $prefix, $table ];
2392         }
2393
2394         /**
2395          * @param string|null $namespace Database or schema
2396          * @param string $relation Name of table, view, sequence, etc...
2397          * @param string $format One of (raw, quoted)
2398          * @return string Relation name with quoted and merged $namespace as needed
2399          */
2400         private function prependDatabaseOrSchema( $namespace, $relation, $format ) {
2401                 if ( strlen( $namespace ) ) {
2402                         if ( $format === 'quoted' && !$this->isQuotedIdentifier( $namespace ) ) {
2403                                 $namespace = $this->addIdentifierQuotes( $namespace );
2404                         }
2405                         $relation = $namespace . '.' . $relation;
2406                 }
2407
2408                 return $relation;
2409         }
2410
2411         public function tableNames() {
2412                 $inArray = func_get_args();
2413                 $retVal = [];
2414
2415                 foreach ( $inArray as $name ) {
2416                         $retVal[$name] = $this->tableName( $name );
2417                 }
2418
2419                 return $retVal;
2420         }
2421
2422         public function tableNamesN() {
2423                 $inArray = func_get_args();
2424                 $retVal = [];
2425
2426                 foreach ( $inArray as $name ) {
2427                         $retVal[] = $this->tableName( $name );
2428                 }
2429
2430                 return $retVal;
2431         }
2432
2433         /**
2434          * Get an aliased table name
2435          *
2436          * This returns strings like "tableName AS newTableName" for aliased tables
2437          * and "(SELECT * from tableA) newTablename" for subqueries (e.g. derived tables)
2438          *
2439          * @see Database::tableName()
2440          * @param string|Subquery $table Table name or object with a 'sql' field
2441          * @param string|bool $alias Table alias (optional)
2442          * @return string SQL name for aliased table. Will not alias a table to its own name
2443          */
2444         protected function tableNameWithAlias( $table, $alias = false ) {
2445                 if ( is_string( $table ) ) {
2446                         $quotedTable = $this->tableName( $table );
2447                 } elseif ( $table instanceof Subquery ) {
2448                         $quotedTable = (string)$table;
2449                 } else {
2450                         throw new InvalidArgumentException( "Table must be a string or Subquery." );
2451                 }
2452
2453                 if ( !strlen( $alias ) || $alias === $table ) {
2454                         if ( $table instanceof Subquery ) {
2455                                 throw new InvalidArgumentException( "Subquery table missing alias." );
2456                         }
2457
2458                         return $quotedTable;
2459                 } else {
2460                         return $quotedTable . ' ' . $this->addIdentifierQuotes( $alias );
2461                 }
2462         }
2463
2464         /**
2465          * Gets an array of aliased table names
2466          *
2467          * @param array $tables [ [alias] => table ]
2468          * @return string[] See tableNameWithAlias()
2469          */
2470         protected function tableNamesWithAlias( $tables ) {
2471                 $retval = [];
2472                 foreach ( $tables as $alias => $table ) {
2473                         if ( is_numeric( $alias ) ) {
2474                                 $alias = $table;
2475                         }
2476                         $retval[] = $this->tableNameWithAlias( $table, $alias );
2477                 }
2478
2479                 return $retval;
2480         }
2481
2482         /**
2483          * Get an aliased field name
2484          * e.g. fieldName AS newFieldName
2485          *
2486          * @param string $name Field name
2487          * @param string|bool $alias Alias (optional)
2488          * @return string SQL name for aliased field. Will not alias a field to its own name
2489          */
2490         protected function fieldNameWithAlias( $name, $alias = false ) {
2491                 if ( !$alias || (string)$alias === (string)$name ) {
2492                         return $name;
2493                 } else {
2494                         return $name . ' AS ' . $this->addIdentifierQuotes( $alias ); // PostgreSQL needs AS
2495                 }
2496         }
2497
2498         /**
2499          * Gets an array of aliased field names
2500          *
2501          * @param array $fields [ [alias] => field ]
2502          * @return string[] See fieldNameWithAlias()
2503          */
2504         protected function fieldNamesWithAlias( $fields ) {
2505                 $retval = [];
2506                 foreach ( $fields as $alias => $field ) {
2507                         if ( is_numeric( $alias ) ) {
2508                                 $alias = $field;
2509                         }
2510                         $retval[] = $this->fieldNameWithAlias( $field, $alias );
2511                 }
2512
2513                 return $retval;
2514         }
2515
2516         /**
2517          * Get the aliased table name clause for a FROM clause
2518          * which might have a JOIN and/or USE INDEX or IGNORE INDEX clause
2519          *
2520          * @param array $tables ( [alias] => table )
2521          * @param array $use_index Same as for select()
2522          * @param array $ignore_index Same as for select()
2523          * @param array $join_conds Same as for select()
2524          * @return string
2525          */
2526         protected function tableNamesWithIndexClauseOrJOIN(
2527                 $tables, $use_index = [], $ignore_index = [], $join_conds = []
2528         ) {
2529                 $ret = [];
2530                 $retJOIN = [];
2531                 $use_index = (array)$use_index;
2532                 $ignore_index = (array)$ignore_index;
2533                 $join_conds = (array)$join_conds;
2534
2535                 foreach ( $tables as $alias => $table ) {
2536                         if ( !is_string( $alias ) ) {
2537                                 // No alias? Set it equal to the table name
2538                                 $alias = $table;
2539                         }
2540
2541                         if ( is_array( $table ) ) {
2542                                 // A parenthesized group
2543                                 if ( count( $table ) > 1 ) {
2544                                         $joinedTable = '(' .
2545                                                 $this->tableNamesWithIndexClauseOrJOIN(
2546                                                         $table, $use_index, $ignore_index, $join_conds ) . ')';
2547                                 } else {
2548                                         // Degenerate case
2549                                         $innerTable = reset( $table );
2550                                         $innerAlias = key( $table );
2551                                         $joinedTable = $this->tableNameWithAlias(
2552                                                 $innerTable,
2553                                                 is_string( $innerAlias ) ? $innerAlias : $innerTable
2554                                         );
2555                                 }
2556                         } else {
2557                                 $joinedTable = $this->tableNameWithAlias( $table, $alias );
2558                         }
2559
2560                         // Is there a JOIN clause for this table?
2561                         if ( isset( $join_conds[$alias] ) ) {
2562                                 list( $joinType, $conds ) = $join_conds[$alias];
2563                                 $tableClause = $joinType;
2564                                 $tableClause .= ' ' . $joinedTable;
2565                                 if ( isset( $use_index[$alias] ) ) { // has USE INDEX?
2566                                         $use = $this->useIndexClause( implode( ',', (array)$use_index[$alias] ) );
2567                                         if ( $use != '' ) {
2568                                                 $tableClause .= ' ' . $use;
2569                                         }
2570                                 }
2571                                 if ( isset( $ignore_index[$alias] ) ) { // has IGNORE INDEX?
2572                                         $ignore = $this->ignoreIndexClause(
2573                                                 implode( ',', (array)$ignore_index[$alias] ) );
2574                                         if ( $ignore != '' ) {
2575                                                 $tableClause .= ' ' . $ignore;
2576                                         }
2577                                 }
2578                                 $on = $this->makeList( (array)$conds, self::LIST_AND );
2579                                 if ( $on != '' ) {
2580                                         $tableClause .= ' ON (' . $on . ')';
2581                                 }
2582
2583                                 $retJOIN[] = $tableClause;
2584                         } elseif ( isset( $use_index[$alias] ) ) {
2585                                 // Is there an INDEX clause for this table?
2586                                 $tableClause = $joinedTable;
2587                                 $tableClause .= ' ' . $this->useIndexClause(
2588                                                 implode( ',', (array)$use_index[$alias] )
2589                                         );
2590
2591                                 $ret[] = $tableClause;
2592                         } elseif ( isset( $ignore_index[$alias] ) ) {
2593                                 // Is there an INDEX clause for this table?
2594                                 $tableClause = $joinedTable;
2595                                 $tableClause .= ' ' . $this->ignoreIndexClause(
2596                                                 implode( ',', (array)$ignore_index[$alias] )
2597                                         );
2598
2599                                 $ret[] = $tableClause;
2600                         } else {
2601                                 $tableClause = $joinedTable;
2602
2603                                 $ret[] = $tableClause;
2604                         }
2605                 }
2606
2607                 // We can't separate explicit JOIN clauses with ',', use ' ' for those
2608                 $implicitJoins = $ret ? implode( ',', $ret ) : "";
2609                 $explicitJoins = $retJOIN ? implode( ' ', $retJOIN ) : "";
2610
2611                 // Compile our final table clause
2612                 return implode( ' ', [ $implicitJoins, $explicitJoins ] );
2613         }
2614
2615         /**
2616          * Allows for index remapping in queries where this is not consistent across DBMS
2617          *
2618          * @param string $index
2619          * @return string
2620          */
2621         protected function indexName( $index ) {
2622                 return $this->indexAliases[$index] ?? $index;
2623         }
2624
2625         public function addQuotes( $s ) {
2626                 if ( $s instanceof Blob ) {
2627                         $s = $s->fetch();
2628                 }
2629                 if ( $s === null ) {
2630                         return 'NULL';
2631                 } elseif ( is_bool( $s ) ) {
2632                         return (int)$s;
2633                 } else {
2634                         # This will also quote numeric values. This should be harmless,
2635                         # and protects against weird problems that occur when they really
2636                         # _are_ strings such as article titles and string->number->string
2637                         # conversion is not 1:1.
2638                         return "'" . $this->strencode( $s ) . "'";
2639                 }
2640         }
2641
2642         /**
2643          * Quotes an identifier using `backticks` or "double quotes" depending on the database type.
2644          * MySQL uses `backticks` while basically everything else uses double quotes.
2645          * Since MySQL is the odd one out here the double quotes are our generic
2646          * and we implement backticks in DatabaseMysqlBase.
2647          *
2648          * @param string $s
2649          * @return string
2650          */
2651         public function addIdentifierQuotes( $s ) {
2652                 return '"' . str_replace( '"', '""', $s ) . '"';
2653         }
2654
2655         /**
2656          * Returns if the given identifier looks quoted or not according to
2657          * the database convention for quoting identifiers .
2658          *
2659          * @note Do not use this to determine if untrusted input is safe.
2660          *   A malicious user can trick this function.
2661          * @param string $name
2662          * @return bool
2663          */
2664         public function isQuotedIdentifier( $name ) {
2665                 return $name[0] == '"' && substr( $name, -1, 1 ) == '"';
2666         }
2667
2668         /**
2669          * @param string $s
2670          * @param string $escapeChar
2671          * @return string
2672          */
2673         protected function escapeLikeInternal( $s, $escapeChar = '`' ) {
2674                 return str_replace( [ $escapeChar, '%', '_' ],
2675                         [ "{$escapeChar}{$escapeChar}", "{$escapeChar}%", "{$escapeChar}_" ],
2676                         $s );
2677         }
2678
2679         public function buildLike() {
2680                 $params = func_get_args();
2681
2682                 if ( count( $params ) > 0 && is_array( $params[0] ) ) {
2683                         $params = $params[0];
2684                 }
2685
2686                 $s = '';
2687
2688                 // We use ` instead of \ as the default LIKE escape character, since addQuotes()
2689                 // may escape backslashes, creating problems of double escaping. The `
2690                 // character has good cross-DBMS compatibility, avoiding special operators
2691                 // in MS SQL like ^ and %
2692                 $escapeChar = '`';
2693
2694                 foreach ( $params as $value ) {
2695                         if ( $value instanceof LikeMatch ) {
2696                                 $s .= $value->toString();
2697                         } else {
2698                                 $s .= $this->escapeLikeInternal( $value, $escapeChar );
2699                         }
2700                 }
2701
2702                 return ' LIKE ' .
2703                         $this->addQuotes( $s ) . ' ESCAPE ' . $this->addQuotes( $escapeChar ) . ' ';
2704         }
2705
2706         public function anyChar() {
2707                 return new LikeMatch( '_' );
2708         }
2709
2710         public function anyString() {
2711                 return new LikeMatch( '%' );
2712         }
2713
2714         public function nextSequenceValue( $seqName ) {
2715                 return null;
2716         }
2717
2718         /**
2719          * USE INDEX clause. Unlikely to be useful for anything but MySQL. This
2720          * is only needed because a) MySQL must be as efficient as possible due to
2721          * its use on Wikipedia, and b) MySQL 4.0 is kind of dumb sometimes about
2722          * which index to pick. Anyway, other databases might have different
2723          * indexes on a given table. So don't bother overriding this unless you're
2724          * MySQL.
2725          * @param string $index
2726          * @return string
2727          */
2728         public function useIndexClause( $index ) {
2729                 return '';
2730         }
2731
2732         /**
2733          * IGNORE INDEX clause. Unlikely to be useful for anything but MySQL. This
2734          * is only needed because a) MySQL must be as efficient as possible due to
2735          * its use on Wikipedia, and b) MySQL 4.0 is kind of dumb sometimes about
2736          * which index to pick. Anyway, other databases might have different
2737          * indexes on a given table. So don't bother overriding this unless you're
2738          * MySQL.
2739          * @param string $index
2740          * @return string
2741          */
2742         public function ignoreIndexClause( $index ) {
2743                 return '';
2744         }
2745
2746         public function replace( $table, $uniqueIndexes, $rows, $fname = __METHOD__ ) {
2747                 if ( count( $rows ) == 0 ) {
2748                         return;
2749                 }
2750
2751                 // Single row case
2752                 if ( !is_array( reset( $rows ) ) ) {
2753                         $rows = [ $rows ];
2754                 }
2755
2756                 try {
2757                         $this->startAtomic( $fname, self::ATOMIC_CANCELABLE );
2758                         $affectedRowCount = 0;
2759                         foreach ( $rows as $row ) {
2760                                 // Delete rows which collide with this one
2761                                 $indexWhereClauses = [];
2762                                 foreach ( $uniqueIndexes as $index ) {
2763                                         $indexColumns = (array)$index;
2764                                         $indexRowValues = array_intersect_key( $row, array_flip( $indexColumns ) );
2765                                         if ( count( $indexRowValues ) != count( $indexColumns ) ) {
2766                                                 throw new DBUnexpectedError(
2767                                                         $this,
2768                                                         'New record does not provide all values for unique key (' .
2769                                                         implode( ', ', $indexColumns ) . ')'
2770                                                 );
2771                                         } elseif ( in_array( null, $indexRowValues, true ) ) {
2772                                                 throw new DBUnexpectedError(
2773                                                         $this,
2774                                                         'New record has a null value for unique key (' .
2775                                                         implode( ', ', $indexColumns ) . ')'
2776                                                 );
2777                                         }
2778                                         $indexWhereClauses[] = $this->makeList( $indexRowValues, LIST_AND );
2779                                 }
2780
2781                                 if ( $indexWhereClauses ) {
2782                                         $this->delete( $table, $this->makeList( $indexWhereClauses, LIST_OR ), $fname );
2783                                         $affectedRowCount += $this->affectedRows();
2784                                 }
2785
2786                                 // Now insert the row
2787                                 $this->insert( $table, $row, $fname );
2788                                 $affectedRowCount += $this->affectedRows();
2789                         }
2790                         $this->endAtomic( $fname );
2791                         $this->affectedRowCount = $affectedRowCount;
2792                 } catch ( Exception $e ) {
2793                         $this->cancelAtomic( $fname );
2794                         throw $e;
2795                 }
2796         }
2797
2798         /**
2799          * REPLACE query wrapper for MySQL and SQLite, which have a native REPLACE
2800          * statement.
2801          *
2802          * @param string $table Table name
2803          * @param array|string $rows Row(s) to insert
2804          * @param string $fname Caller function name
2805          *
2806          * @return ResultWrapper
2807          */
2808         protected function nativeReplace( $table, $rows, $fname ) {
2809                 $table = $this->tableName( $table );
2810
2811                 # Single row case
2812                 if ( !is_array( reset( $rows ) ) ) {
2813                         $rows = [ $rows ];
2814                 }
2815
2816                 $sql = "REPLACE INTO $table (" . implode( ',', array_keys( $rows[0] ) ) . ') VALUES ';
2817                 $first = true;
2818
2819                 foreach ( $rows as $row ) {
2820                         if ( $first ) {
2821                                 $first = false;
2822                         } else {
2823                                 $sql .= ',';
2824                         }
2825
2826                         $sql .= '(' . $this->makeList( $row ) . ')';
2827                 }
2828
2829                 return $this->query( $sql, $fname );
2830         }
2831
2832         public function upsert( $table, array $rows, array $uniqueIndexes, array $set,
2833                 $fname = __METHOD__
2834         ) {
2835                 if ( !count( $rows ) ) {
2836                         return true; // nothing to do
2837                 }
2838
2839                 if ( !is_array( reset( $rows ) ) ) {
2840                         $rows = [ $rows ];
2841                 }
2842
2843                 if ( count( $uniqueIndexes ) ) {
2844                         $clauses = []; // list WHERE clauses that each identify a single row
2845                         foreach ( $rows as $row ) {
2846                                 foreach ( $uniqueIndexes as $index ) {
2847                                         $index = is_array( $index ) ? $index : [ $index ]; // columns
2848                                         $rowKey = []; // unique key to this row
2849                                         foreach ( $index as $column ) {
2850                                                 $rowKey[$column] = $row[$column];
2851                                         }
2852                                         $clauses[] = $this->makeList( $rowKey, self::LIST_AND );
2853                                 }
2854                         }
2855                         $where = [ $this->makeList( $clauses, self::LIST_OR ) ];
2856                 } else {
2857                         $where = false;
2858                 }
2859
2860                 $affectedRowCount = 0;
2861                 try {
2862                         $this->startAtomic( $fname, self::ATOMIC_CANCELABLE );
2863                         # Update any existing conflicting row(s)
2864                         if ( $where !== false ) {
2865                                 $ok = $this->update( $table, $set, $where, $fname );
2866                                 $affectedRowCount += $this->affectedRows();
2867                         } else {
2868                                 $ok = true;
2869                         }
2870                         # Now insert any non-conflicting row(s)
2871                         $ok = $this->insert( $table, $rows, $fname, [ 'IGNORE' ] ) && $ok;
2872                         $affectedRowCount += $this->affectedRows();
2873                         $this->endAtomic( $fname );
2874                         $this->affectedRowCount = $affectedRowCount;
2875                 } catch ( Exception $e ) {
2876                         $this->cancelAtomic( $fname );
2877                         throw $e;
2878                 }
2879
2880                 return $ok;
2881         }
2882
2883         public function deleteJoin( $delTable, $joinTable, $delVar, $joinVar, $conds,
2884                 $fname = __METHOD__
2885         ) {
2886                 if ( !$conds ) {
2887                         throw new DBUnexpectedError( $this, __METHOD__ . ' called with empty $conds' );
2888                 }
2889
2890                 $delTable = $this->tableName( $delTable );
2891                 $joinTable = $this->tableName( $joinTable );
2892                 $sql = "DELETE FROM $delTable WHERE $delVar IN (SELECT $joinVar FROM $joinTable ";
2893                 if ( $conds != '*' ) {
2894                         $sql .= 'WHERE ' . $this->makeList( $conds, self::LIST_AND );
2895                 }
2896                 $sql .= ')';
2897
2898                 $this->query( $sql, $fname );
2899         }
2900
2901         public function textFieldSize( $table, $field ) {
2902                 $table = $this->tableName( $table );
2903                 $sql = "SHOW COLUMNS FROM $table LIKE \"$field\";";
2904                 $res = $this->query( $sql, __METHOD__ );
2905                 $row = $this->fetchObject( $res );
2906
2907                 $m = [];
2908
2909                 if ( preg_match( '/\((.*)\)/', $row->Type, $m ) ) {
2910                         $size = $m[1];
2911                 } else {
2912                         $size = -1;
2913                 }
2914
2915                 return $size;
2916         }
2917
2918         public function delete( $table, $conds, $fname = __METHOD__ ) {
2919                 if ( !$conds ) {
2920                         throw new DBUnexpectedError( $this, __METHOD__ . ' called with no conditions' );
2921                 }
2922
2923                 $table = $this->tableName( $table );
2924                 $sql = "DELETE FROM $table";
2925
2926                 if ( $conds != '*' ) {
2927                         if ( is_array( $conds ) ) {
2928                                 $conds = $this->makeList( $conds, self::LIST_AND );
2929                         }
2930                         $sql .= ' WHERE ' . $conds;
2931                 }
2932
2933                 return $this->query( $sql, $fname );
2934         }
2935
2936         final public function insertSelect(
2937                 $destTable, $srcTable, $varMap, $conds,
2938                 $fname = __METHOD__, $insertOptions = [], $selectOptions = [], $selectJoinConds = []
2939         ) {
2940                 static $hints = [ 'NO_AUTO_COLUMNS' ];
2941
2942                 $insertOptions = (array)$insertOptions;
2943                 $selectOptions = (array)$selectOptions;
2944
2945                 if ( $this->cliMode && $this->isInsertSelectSafe( $insertOptions, $selectOptions ) ) {
2946                         // For massive migrations with downtime, we don't want to select everything
2947                         // into memory and OOM, so do all this native on the server side if possible.
2948                         return $this->nativeInsertSelect(
2949                                 $destTable,
2950                                 $srcTable,
2951                                 $varMap,
2952                                 $conds,
2953                                 $fname,
2954                                 array_diff( $insertOptions, $hints ),
2955                                 $selectOptions,
2956                                 $selectJoinConds
2957                         );
2958                 }
2959
2960                 return $this->nonNativeInsertSelect(
2961                         $destTable,
2962                         $srcTable,
2963                         $varMap,
2964                         $conds,
2965                         $fname,
2966                         array_diff( $insertOptions, $hints ),
2967                         $selectOptions,
2968                         $selectJoinConds
2969                 );
2970         }
2971
2972         /**
2973          * @param array $insertOptions INSERT options
2974          * @param array $selectOptions SELECT options
2975          * @return bool Whether an INSERT SELECT with these options will be replication safe
2976          * @since 1.31
2977          */
2978         protected function isInsertSelectSafe( array $insertOptions, array $selectOptions ) {
2979                 return true;
2980         }
2981
2982         /**
2983          * Implementation of insertSelect() based on select() and insert()
2984          *
2985          * @see IDatabase::insertSelect()
2986          * @since 1.30
2987          * @param string $destTable
2988          * @param string|array $srcTable
2989          * @param array $varMap
2990          * @param array $conds
2991          * @param string $fname
2992          * @param array $insertOptions
2993          * @param array $selectOptions
2994          * @param array $selectJoinConds
2995          * @return bool
2996          */
2997         protected function nonNativeInsertSelect( $destTable, $srcTable, $varMap, $conds,
2998                 $fname = __METHOD__,
2999                 $insertOptions = [], $selectOptions = [], $selectJoinConds = []
3000         ) {
3001                 // For web requests, do a locking SELECT and then INSERT. This puts the SELECT burden
3002                 // on only the master (without needing row-based-replication). It also makes it easy to
3003                 // know how big the INSERT is going to be.
3004                 $fields = [];
3005                 foreach ( $varMap as $dstColumn => $sourceColumnOrSql ) {
3006                         $fields[] = $this->fieldNameWithAlias( $sourceColumnOrSql, $dstColumn );
3007                 }
3008                 $selectOptions[] = 'FOR UPDATE';
3009                 $res = $this->select(
3010                         $srcTable, implode( ',', $fields ), $conds, $fname, $selectOptions, $selectJoinConds
3011                 );
3012                 if ( !$res ) {
3013                         return false;
3014                 }
3015
3016                 try {
3017                         $affectedRowCount = 0;
3018                         $this->startAtomic( $fname, self::ATOMIC_CANCELABLE );
3019                         $rows = [];
3020                         $ok = true;
3021                         foreach ( $res as $row ) {
3022                                 $rows[] = (array)$row;
3023
3024                                 // Avoid inserts that are too huge
3025                                 if ( count( $rows ) >= $this->nonNativeInsertSelectBatchSize ) {
3026                                         $ok = $this->insert( $destTable, $rows, $fname, $insertOptions );
3027                                         if ( !$ok ) {
3028                                                 break;
3029                                         }
3030                                         $affectedRowCount += $this->affectedRows();
3031                                         $rows = [];
3032                                 }
3033                         }
3034                         if ( $rows && $ok ) {
3035                                 $ok = $this->insert( $destTable, $rows, $fname, $insertOptions );
3036                                 if ( $ok ) {
3037                                         $affectedRowCount += $this->affectedRows();
3038                                 }
3039                         }
3040                         if ( $ok ) {
3041                                 $this->endAtomic( $fname );
3042                                 $this->affectedRowCount = $affectedRowCount;
3043                         } else {
3044                                 $this->cancelAtomic( $fname );
3045                         }
3046                         return $ok;
3047                 } catch ( Exception $e ) {
3048                         $this->cancelAtomic( $fname );
3049                         throw $e;
3050                 }
3051         }
3052
3053         /**
3054          * Native server-side implementation of insertSelect() for situations where
3055          * we don't want to select everything into memory
3056          *
3057          * @see IDatabase::insertSelect()
3058          * @param string $destTable
3059          * @param string|array $srcTable
3060          * @param array $varMap
3061          * @param array $conds
3062          * @param string $fname
3063          * @param array $insertOptions
3064          * @param array $selectOptions
3065          * @param array $selectJoinConds
3066          * @return bool
3067          */
3068         protected function nativeInsertSelect( $destTable, $srcTable, $varMap, $conds,
3069                 $fname = __METHOD__,
3070                 $insertOptions = [], $selectOptions = [], $selectJoinConds = []
3071         ) {
3072                 $destTable = $this->tableName( $destTable );
3073
3074                 if ( !is_array( $insertOptions ) ) {
3075                         $insertOptions = [ $insertOptions ];
3076                 }
3077
3078                 $insertOptions = $this->makeInsertOptions( $insertOptions );
3079
3080                 $selectSql = $this->selectSQLText(
3081                         $srcTable,
3082                         array_values( $varMap ),
3083                         $conds,
3084                         $fname,
3085                         $selectOptions,
3086                         $selectJoinConds
3087                 );
3088
3089                 $sql = "INSERT $insertOptions" .
3090                         " INTO $destTable (" . implode( ',', array_keys( $varMap ) ) . ') ' .
3091                         $selectSql;
3092
3093                 return $this->query( $sql, $fname );
3094         }
3095
3096         /**
3097          * Construct a LIMIT query with optional offset. This is used for query
3098          * pages. The SQL should be adjusted so that only the first $limit rows
3099          * are returned. If $offset is provided as well, then the first $offset
3100          * rows should be discarded, and the next $limit rows should be returned.
3101          * If the result of the query is not ordered, then the rows to be returned
3102          * are theoretically arbitrary.
3103          *
3104          * $sql is expected to be a SELECT, if that makes a difference.
3105          *
3106          * The version provided by default works in MySQL and SQLite. It will very
3107          * likely need to be overridden for most other DBMSes.
3108          *
3109          * @param string $sql SQL query we will append the limit too
3110          * @param int $limit The SQL limit
3111          * @param int|bool $offset The SQL offset (default false)
3112          * @throws DBUnexpectedError
3113          * @return string
3114          */
3115         public function limitResult( $sql, $limit, $offset = false ) {
3116                 if ( !is_numeric( $limit ) ) {
3117                         throw new DBUnexpectedError( $this,
3118                                 "Invalid non-numeric limit passed to limitResult()\n" );
3119                 }
3120
3121                 return "$sql LIMIT "
3122                 . ( ( is_numeric( $offset ) && $offset != 0 ) ? "{$offset}," : "" )
3123                 . "{$limit} ";
3124         }
3125
3126         public function unionSupportsOrderAndLimit() {
3127                 return true; // True for almost every DB supported
3128         }
3129
3130         public function unionQueries( $sqls, $all ) {
3131                 $glue = $all ? ') UNION ALL (' : ') UNION (';
3132
3133                 return '(' . implode( $glue, $sqls ) . ')';
3134         }
3135
3136         public function unionConditionPermutations(
3137                 $table, $vars, array $permute_conds, $extra_conds = '', $fname = __METHOD__,
3138                 $options = [], $join_conds = []
3139         ) {
3140                 // First, build the Cartesian product of $permute_conds
3141                 $conds = [ [] ];
3142                 foreach ( $permute_conds as $field => $values ) {
3143                         if ( !$values ) {
3144                                 // Skip empty $values
3145                                 continue;
3146                         }
3147                         $values = array_unique( $values ); // For sanity
3148                         $newConds = [];
3149                         foreach ( $conds as $cond ) {
3150                                 foreach ( $values as $value ) {
3151                                         $cond[$field] = $value;
3152                                         $newConds[] = $cond; // Arrays are by-value, not by-reference, so this works
3153                                 }
3154                         }
3155                         $conds = $newConds;
3156                 }
3157
3158                 $extra_conds = $extra_conds === '' ? [] : (array)$extra_conds;
3159
3160                 // If there's just one condition and no subordering, hand off to
3161                 // selectSQLText directly.
3162                 if ( count( $conds ) === 1 &&
3163                         ( !isset( $options['INNER ORDER BY'] ) || !$this->unionSupportsOrderAndLimit() )
3164                 ) {
3165                         return $this->selectSQLText(
3166                                 $table, $vars, $conds[0] + $extra_conds, $fname, $options, $join_conds
3167                         );
3168                 }
3169
3170                 // Otherwise, we need to pull out the order and limit to apply after
3171                 // the union. Then build the SQL queries for each set of conditions in
3172                 // $conds. Then union them together (using UNION ALL, because the
3173                 // product *should* already be distinct).
3174                 $orderBy = $this->makeOrderBy( $options );
3175                 $limit = $options['LIMIT'] ?? null;
3176                 $offset = $options['OFFSET'] ?? false;
3177                 $all = empty( $options['NOTALL'] ) && !in_array( 'NOTALL', $options );
3178                 if ( !$this->unionSupportsOrderAndLimit() ) {
3179                         unset( $options['ORDER BY'], $options['LIMIT'], $options['OFFSET'] );
3180                 } else {
3181                         if ( array_key_exists( 'INNER ORDER BY', $options ) ) {
3182                                 $options['ORDER BY'] = $options['INNER ORDER BY'];
3183                         }
3184                         if ( $limit !== null && is_numeric( $offset ) && $offset != 0 ) {
3185                                 // We need to increase the limit by the offset rather than
3186                                 // using the offset directly, otherwise it'll skip incorrectly
3187                                 // in the subqueries.
3188                                 $options['LIMIT'] = $limit + $offset;
3189                                 unset( $options['OFFSET'] );
3190                         }
3191                 }
3192
3193                 $sqls = [];
3194                 foreach ( $conds as $cond ) {
3195                         $sqls[] = $this->selectSQLText(
3196                                 $table, $vars, $cond + $extra_conds, $fname, $options, $join_conds
3197                         );
3198                 }
3199                 $sql = $this->unionQueries( $sqls, $all ) . $orderBy;
3200                 if ( $limit !== null ) {
3201                         $sql = $this->limitResult( $sql, $limit, $offset );
3202                 }
3203
3204                 return $sql;
3205         }
3206
3207         public function conditional( $cond, $trueVal, $falseVal ) {
3208                 if ( is_array( $cond ) ) {
3209                         $cond = $this->makeList( $cond, self::LIST_AND );
3210                 }
3211
3212                 return " (CASE WHEN $cond THEN $trueVal ELSE $falseVal END) ";
3213         }
3214
3215         public function strreplace( $orig, $old, $new ) {
3216                 return "REPLACE({$orig}, {$old}, {$new})";
3217         }
3218
3219         public function getServerUptime() {
3220                 return 0;
3221         }
3222
3223         public function wasDeadlock() {
3224                 return false;
3225         }
3226
3227         public function wasLockTimeout() {
3228                 return false;
3229         }
3230
3231         public function wasConnectionLoss() {
3232                 return $this->wasConnectionError( $this->lastErrno() );
3233         }
3234
3235         public function wasReadOnlyError() {
3236                 return false;
3237         }
3238
3239         public function wasErrorReissuable() {
3240                 return (
3241                         $this->wasDeadlock() ||
3242                         $this->wasLockTimeout() ||
3243                         $this->wasConnectionLoss()
3244                 );
3245         }
3246
3247         /**
3248          * Do not use this method outside of Database/DBError classes
3249          *
3250          * @param int|string $errno
3251          * @return bool Whether the given query error was a connection drop
3252          */
3253         public function wasConnectionError( $errno ) {
3254                 return false;
3255         }
3256
3257         /**
3258          * @return bool Whether it is safe to assume the given error only caused statement rollback
3259          * @note This is for backwards compatibility for callers catching DBError exceptions in
3260          *   order to ignore problems like duplicate key errors or foriegn key violations
3261          * @since 1.31
3262          */
3263         protected function wasKnownStatementRollbackError() {
3264                 return false; // don't know; it could have caused a transaction rollback
3265         }
3266
3267         public function deadlockLoop() {
3268                 $args = func_get_args();
3269                 $function = array_shift( $args );
3270                 $tries = self::DEADLOCK_TRIES;
3271
3272                 $this->begin( __METHOD__ );
3273
3274                 $retVal = null;
3275                 /** @var Exception $e */
3276                 $e = null;
3277                 do {
3278                         try {
3279                                 $retVal = $function( ...$args );
3280                                 break;
3281                         } catch ( DBQueryError $e ) {
3282                                 if ( $this->wasDeadlock() ) {
3283                                         // Retry after a randomized delay
3284                                         usleep( mt_rand( self::DEADLOCK_DELAY_MIN, self::DEADLOCK_DELAY_MAX ) );
3285                                 } else {
3286                                         // Throw the error back up
3287                                         throw $e;
3288                                 }
3289                         }
3290                 } while ( --$tries > 0 );
3291
3292                 if ( $tries <= 0 ) {
3293                         // Too many deadlocks; give up
3294                         $this->rollback( __METHOD__ );
3295                         throw $e;
3296                 } else {
3297                         $this->commit( __METHOD__ );
3298
3299                         return $retVal;
3300                 }
3301         }
3302
3303         public function masterPosWait( DBMasterPos $pos, $timeout ) {
3304                 # Real waits are implemented in the subclass.
3305                 return 0;
3306         }
3307
3308         public function getReplicaPos() {
3309                 # Stub
3310                 return false;
3311         }
3312
3313         public function getMasterPos() {
3314                 # Stub
3315                 return false;
3316         }
3317
3318         public function serverIsReadOnly() {
3319                 return false;
3320         }
3321
3322         final public function onTransactionResolution( callable $callback, $fname = __METHOD__ ) {
3323                 if ( !$this->trxLevel ) {
3324                         throw new DBUnexpectedError( $this, "No transaction is active." );
3325                 }
3326                 $this->trxEndCallbacks[] = [ $callback, $fname, $this->currentAtomicSectionId() ];
3327         }
3328
3329         final public function onTransactionCommitOrIdle( callable $callback, $fname = __METHOD__ ) {
3330                 if ( !$this->trxLevel && $this->getTransactionRoundId() ) {
3331                         // Start an implicit transaction similar to how query() does
3332                         $this->begin( __METHOD__, self::TRANSACTION_INTERNAL );
3333                         $this->trxAutomatic = true;
3334                 }
3335
3336                 $this->trxIdleCallbacks[] = [ $callback, $fname, $this->currentAtomicSectionId() ];
3337                 if ( !$this->trxLevel ) {
3338                         $this->runOnTransactionIdleCallbacks( self::TRIGGER_IDLE );
3339                 }
3340         }
3341
3342         final public function onTransactionIdle( callable $callback, $fname = __METHOD__ ) {
3343                 $this->onTransactionCommitOrIdle( $callback, $fname );
3344         }
3345
3346         final public function onTransactionPreCommitOrIdle( callable $callback, $fname = __METHOD__ ) {
3347                 if ( !$this->trxLevel && $this->getTransactionRoundId() ) {
3348                         // Start an implicit transaction similar to how query() does
3349                         $this->begin( __METHOD__, self::TRANSACTION_INTERNAL );
3350                         $this->trxAutomatic = true;
3351                 }
3352
3353                 if ( $this->trxLevel ) {
3354                         $this->trxPreCommitCallbacks[] = [ $callback, $fname, $this->currentAtomicSectionId() ];
3355                 } else {
3356                         // No transaction is active nor will start implicitly, so make one for this callback
3357                         $this->startAtomic( __METHOD__, self::ATOMIC_CANCELABLE );
3358                         try {
3359                                 $callback( $this );
3360                                 $this->endAtomic( __METHOD__ );
3361                         } catch ( Exception $e ) {
3362                                 $this->cancelAtomic( __METHOD__ );
3363                                 throw $e;
3364                         }
3365                 }
3366         }
3367
3368         /**
3369          * @return AtomicSectionIdentifier|null ID of the topmost atomic section level
3370          */
3371         private function currentAtomicSectionId() {
3372                 if ( $this->trxLevel && $this->trxAtomicLevels ) {
3373                         $levelInfo = end( $this->trxAtomicLevels );
3374
3375                         return $levelInfo[1];
3376                 }
3377
3378                 return null;
3379         }
3380
3381         /**
3382          * @param AtomicSectionIdentifier $old
3383          * @param AtomicSectionIdentifier $new
3384          */
3385         private function reassignCallbacksForSection(
3386                 AtomicSectionIdentifier $old, AtomicSectionIdentifier $new
3387         ) {
3388                 foreach ( $this->trxPreCommitCallbacks as $key => $info ) {
3389                         if ( $info[2] === $old ) {
3390                                 $this->trxPreCommitCallbacks[$key][2] = $new;
3391                         }
3392                 }
3393                 foreach ( $this->trxIdleCallbacks as $key => $info ) {
3394                         if ( $info[2] === $old ) {
3395                                 $this->trxIdleCallbacks[$key][2] = $new;
3396                         }
3397                 }
3398                 foreach ( $this->trxEndCallbacks as $key => $info ) {
3399                         if ( $info[2] === $old ) {
3400                                 $this->trxEndCallbacks[$key][2] = $new;
3401                         }
3402                 }
3403         }
3404
3405         /**
3406          * @param AtomicSectionIdentifier[] $sectionIds ID of an actual savepoint
3407          * @throws UnexpectedValueException
3408          */
3409         private function modifyCallbacksForCancel( array $sectionIds ) {
3410                 // Cancel the "on commit" callbacks owned by this savepoint
3411                 $this->trxIdleCallbacks = array_filter(
3412                         $this->trxIdleCallbacks,
3413                         function ( $entry ) use ( $sectionIds ) {
3414                                 return !in_array( $entry[2], $sectionIds, true );
3415                         }
3416                 );
3417                 $this->trxPreCommitCallbacks = array_filter(
3418                         $this->trxPreCommitCallbacks,
3419                         function ( $entry ) use ( $sectionIds ) {
3420                                 return !in_array( $entry[2], $sectionIds, true );
3421                         }
3422                 );
3423                 // Make "on resolution" callbacks owned by this savepoint to perceive a rollback
3424                 foreach ( $this->trxEndCallbacks as $key => $entry ) {
3425                         if ( in_array( $entry[2], $sectionIds, true ) ) {
3426                                 $callback = $entry[0];
3427                                 $this->trxEndCallbacks[$key][0] = function () use ( $callback ) {
3428                                         return $callback( self::TRIGGER_ROLLBACK, $this );
3429                                 };
3430                         }
3431                 }
3432         }
3433
3434         final public function setTransactionListener( $name, callable $callback = null ) {
3435                 if ( $callback ) {
3436                         $this->trxRecurringCallbacks[$name] = $callback;
3437                 } else {
3438                         unset( $this->trxRecurringCallbacks[$name] );
3439                 }
3440         }
3441
3442         /**
3443          * Whether to disable running of post-COMMIT/ROLLBACK callbacks
3444          *
3445          * This method should not be used outside of Database/LoadBalancer
3446          *
3447          * @param bool $suppress
3448          * @since 1.28
3449          */
3450         final public function setTrxEndCallbackSuppression( $suppress ) {
3451                 $this->trxEndCallbacksSuppressed = $suppress;
3452         }
3453
3454         /**
3455          * Actually consume and run any "on transaction idle/resolution" callbacks.
3456          *
3457          * This method should not be used outside of Database/LoadBalancer
3458          *
3459          * @param int $trigger IDatabase::TRIGGER_* constant
3460          * @return int Number of callbacks attempted
3461          * @since 1.20
3462          * @throws Exception
3463          */
3464         public function runOnTransactionIdleCallbacks( $trigger ) {
3465                 if ( $this->trxLevel ) { // sanity
3466                         throw new DBUnexpectedError( $this, __METHOD__ . ': a transaction is still open.' );
3467                 }
3468
3469                 if ( $this->trxEndCallbacksSuppressed ) {
3470                         return 0;
3471                 }
3472
3473                 $count = 0;
3474                 $autoTrx = $this->getFlag( self::DBO_TRX ); // automatic begin() enabled?
3475                 /** @var Exception $e */
3476                 $e = null; // first exception
3477                 do { // callbacks may add callbacks :)
3478                         $callbacks = array_merge(
3479                                 $this->trxIdleCallbacks,
3480                                 $this->trxEndCallbacks // include "transaction resolution" callbacks
3481                         );
3482                         $this->trxIdleCallbacks = []; // consumed (and recursion guard)
3483                         $this->trxEndCallbacks = []; // consumed (recursion guard)
3484                         foreach ( $callbacks as $callback ) {
3485                                 ++$count;
3486                                 list( $phpCallback ) = $callback;
3487                                 $this->clearFlag( self::DBO_TRX ); // make each query its own transaction
3488                                 try {
3489                                         call_user_func( $phpCallback, $trigger, $this );
3490                                 } catch ( Exception $ex ) {
3491                                         call_user_func( $this->errorLogger, $ex );
3492                                         $e = $e ?: $ex;
3493                                         // Some callbacks may use startAtomic/endAtomic, so make sure
3494                                         // their transactions are ended so other callbacks don't fail
3495                                         if ( $this->trxLevel() ) {
3496                                                 $this->rollback( __METHOD__, self::FLUSHING_INTERNAL );
3497                                         }
3498                                 } finally {
3499                                         if ( $autoTrx ) {
3500                                                 $this->setFlag( self::DBO_TRX ); // restore automatic begin()
3501                                         } else {
3502                                                 $this->clearFlag( self::DBO_TRX ); // restore auto-commit
3503                                         }
3504                                 }
3505                         }
3506                 } while ( count( $this->trxIdleCallbacks ) );
3507
3508                 if ( $e instanceof Exception ) {
3509                         throw $e; // re-throw any first exception
3510                 }
3511
3512                 return $count;
3513         }
3514
3515         /**
3516          * Actually consume and run any "on transaction pre-commit" callbacks.
3517          *
3518          * This method should not be used outside of Database/LoadBalancer
3519          *
3520          * @since 1.22
3521          * @return int Number of callbacks attempted
3522          * @throws Exception
3523          */
3524         public function runOnTransactionPreCommitCallbacks() {
3525                 $count = 0;
3526
3527                 $e = null; // first exception
3528                 do { // callbacks may add callbacks :)
3529                         $callbacks = $this->trxPreCommitCallbacks;
3530                         $this->trxPreCommitCallbacks = []; // consumed (and recursion guard)
3531                         foreach ( $callbacks as $callback ) {
3532                                 try {
3533                                         ++$count;
3534                                         list( $phpCallback ) = $callback;
3535                                         $phpCallback( $this );
3536                                 } catch ( Exception $ex ) {
3537                                         ( $this->errorLogger )( $ex );
3538                                         $e = $e ?: $ex;
3539                                 }
3540                         }
3541                 } while ( count( $this->trxPreCommitCallbacks ) );
3542
3543                 if ( $e instanceof Exception ) {
3544                         throw $e; // re-throw any first exception
3545                 }
3546
3547                 return $count;
3548         }
3549
3550         /**
3551          * Actually run any "transaction listener" callbacks.
3552          *
3553          * This method should not be used outside of Database/LoadBalancer
3554          *
3555          * @param int $trigger IDatabase::TRIGGER_* constant
3556          * @throws Exception
3557          * @since 1.20
3558          */
3559         public function runTransactionListenerCallbacks( $trigger ) {
3560                 if ( $this->trxEndCallbacksSuppressed ) {
3561                         return;
3562                 }
3563
3564                 /** @var Exception $e */
3565                 $e = null; // first exception
3566
3567                 foreach ( $this->trxRecurringCallbacks as $phpCallback ) {
3568                         try {
3569                                 $phpCallback( $trigger, $this );
3570                         } catch ( Exception $ex ) {
3571                                 ( $this->errorLogger )( $ex );
3572                                 $e = $e ?: $ex;
3573                         }
3574                 }
3575
3576                 if ( $e instanceof Exception ) {
3577                         throw $e; // re-throw any first exception
3578                 }
3579         }
3580
3581         /**
3582          * Create a savepoint
3583          *
3584          * This is used internally to implement atomic sections. It should not be
3585          * used otherwise.
3586          *
3587          * @since 1.31
3588          * @param string $identifier Identifier for the savepoint
3589          * @param string $fname Calling function name
3590          */
3591         protected function doSavepoint( $identifier, $fname ) {
3592                 $this->query( 'SAVEPOINT ' . $this->addIdentifierQuotes( $identifier ), $fname );
3593         }
3594
3595         /**
3596          * Release a savepoint
3597          *
3598          * This is used internally to implement atomic sections. It should not be
3599          * used otherwise.
3600          *
3601          * @since 1.31
3602          * @param string $identifier Identifier for the savepoint
3603          * @param string $fname Calling function name
3604          */
3605         protected function doReleaseSavepoint( $identifier, $fname ) {
3606                 $this->query( 'RELEASE SAVEPOINT ' . $this->addIdentifierQuotes( $identifier ), $fname );
3607         }
3608
3609         /**
3610          * Rollback to a savepoint
3611          *
3612          * This is used internally to implement atomic sections. It should not be
3613          * used otherwise.
3614          *
3615          * @since 1.31
3616          * @param string $identifier Identifier for the savepoint
3617          * @param string $fname Calling function name
3618          */
3619         protected function doRollbackToSavepoint( $identifier, $fname ) {
3620                 $this->query( 'ROLLBACK TO SAVEPOINT ' . $this->addIdentifierQuotes( $identifier ), $fname );
3621         }
3622
3623         /**
3624          * @param string $fname
3625          * @return string
3626          */
3627         private function nextSavepointId( $fname ) {
3628                 $savepointId = self::$SAVEPOINT_PREFIX . ++$this->trxAtomicCounter;
3629                 if ( strlen( $savepointId ) > 30 ) {
3630                         // 30 == Oracle's identifier length limit (pre 12c)
3631                         // With a 22 character prefix, that puts the highest number at 99999999.
3632                         throw new DBUnexpectedError(
3633                                 $this,
3634                                 'There have been an excessively large number of atomic sections in a transaction'
3635                                 . " started by $this->trxFname (at $fname)"
3636                         );
3637                 }
3638
3639                 return $savepointId;
3640         }
3641
3642         final public function startAtomic(
3643                 $fname = __METHOD__, $cancelable = self::ATOMIC_NOT_CANCELABLE
3644         ) {
3645                 $savepointId = $cancelable === self::ATOMIC_CANCELABLE ? self::$NOT_APPLICABLE : null;
3646
3647                 if ( !$this->trxLevel ) {
3648                         $this->begin( $fname, self::TRANSACTION_INTERNAL ); // sets trxAutomatic
3649                         // If DBO_TRX is set, a series of startAtomic/endAtomic pairs will result
3650                         // in all changes being in one transaction to keep requests transactional.
3651                         if ( $this->getFlag( self::DBO_TRX ) ) {
3652                                 // Since writes could happen in between the topmost atomic sections as part
3653                                 // of the transaction, those sections will need savepoints.
3654                                 $savepointId = $this->nextSavepointId( $fname );
3655                                 $this->doSavepoint( $savepointId, $fname );
3656                         } else {
3657                                 $this->trxAutomaticAtomic = true;
3658                         }
3659                 } elseif ( $cancelable === self::ATOMIC_CANCELABLE ) {
3660                         $savepointId = $this->nextSavepointId( $fname );
3661                         $this->doSavepoint( $savepointId, $fname );
3662                 }
3663
3664                 $sectionId = new AtomicSectionIdentifier;
3665                 $this->trxAtomicLevels[] = [ $fname, $sectionId, $savepointId ];
3666
3667                 return $sectionId;
3668         }
3669
3670         final public function endAtomic( $fname = __METHOD__ ) {
3671                 if ( !$this->trxLevel || !$this->trxAtomicLevels ) {
3672                         throw new DBUnexpectedError( $this, "No atomic section is open (got $fname)." );
3673                 }
3674
3675                 // Check if the current section matches $fname
3676                 $pos = count( $this->trxAtomicLevels ) - 1;
3677                 list( $savedFname, $sectionId, $savepointId ) = $this->trxAtomicLevels[$pos];
3678
3679                 if ( $savedFname !== $fname ) {
3680                         throw new DBUnexpectedError(
3681                                 $this,
3682                                 "Invalid atomic section ended (got $fname but expected $savedFname)."
3683                         );
3684                 }
3685
3686                 // Remove the last section (no need to re-index the array)
3687                 array_pop( $this->trxAtomicLevels );
3688
3689                 if ( !$this->trxAtomicLevels && $this->trxAutomaticAtomic ) {
3690                         $this->commit( $fname, self::FLUSHING_INTERNAL );
3691                 } elseif ( $savepointId !== null && $savepointId !== self::$NOT_APPLICABLE ) {
3692                         $this->doReleaseSavepoint( $savepointId, $fname );
3693                 }
3694
3695                 // Hoist callback ownership for callbacks in the section that just ended;
3696                 // all callbacks should have an owner that is present in trxAtomicLevels.
3697                 $currentSectionId = $this->currentAtomicSectionId();
3698                 if ( $currentSectionId ) {
3699                         $this->reassignCallbacksForSection( $sectionId, $currentSectionId );
3700                 }
3701         }
3702
3703         final public function cancelAtomic(
3704                 $fname = __METHOD__, AtomicSectionIdentifier $sectionId = null
3705         ) {
3706                 if ( !$this->trxLevel || !$this->trxAtomicLevels ) {
3707                         throw new DBUnexpectedError( $this, "No atomic section is open (got $fname)." );
3708                 }
3709
3710                 if ( $sectionId !== null ) {
3711                         // Find the (last) section with the given $sectionId
3712                         $pos = -1;
3713                         foreach ( $this->trxAtomicLevels as $i => list( $asFname, $asId, $spId ) ) {
3714                                 if ( $asId === $sectionId ) {
3715                                         $pos = $i;
3716                                 }
3717                         }
3718                         if ( $pos < 0 ) {
3719                                 throw new DBUnexpectedError( "Atomic section not found (for $fname)" );
3720                         }
3721                         // Remove all descendant sections and re-index the array
3722                         $excisedIds = [];
3723                         $len = count( $this->trxAtomicLevels );
3724                         for ( $i = $pos + 1; $i < $len; ++$i ) {
3725                                 $excisedIds[] = $this->trxAtomicLevels[$i][1];
3726                         }
3727                         $this->trxAtomicLevels = array_slice( $this->trxAtomicLevels, 0, $pos + 1 );
3728                         $this->modifyCallbacksForCancel( $excisedIds );
3729                 }
3730
3731                 // Check if the current section matches $fname
3732                 $pos = count( $this->trxAtomicLevels ) - 1;
3733                 list( $savedFname, $savedSectionId, $savepointId ) = $this->trxAtomicLevels[$pos];
3734
3735                 if ( $savedFname !== $fname ) {
3736                         throw new DBUnexpectedError(
3737                                 $this,
3738                                 "Invalid atomic section ended (got $fname but expected $savedFname)."
3739                         );
3740                 }
3741
3742                 // Remove the last section (no need to re-index the array)
3743                 array_pop( $this->trxAtomicLevels );
3744                 $this->modifyCallbacksForCancel( [ $savedSectionId ] );
3745
3746                 if ( $savepointId !== null ) {
3747                         // Rollback the transaction to the state just before this atomic section
3748                         if ( $savepointId === self::$NOT_APPLICABLE ) {
3749                                 $this->rollback( $fname, self::FLUSHING_INTERNAL );
3750                         } else {
3751                                 $this->doRollbackToSavepoint( $savepointId, $fname );
3752                                 $this->trxStatus = self::STATUS_TRX_OK; // no exception; recovered
3753                                 $this->trxStatusIgnoredCause = null;
3754                         }
3755                 } elseif ( $this->trxStatus > self::STATUS_TRX_ERROR ) {
3756                         // Put the transaction into an error state if it's not already in one
3757                         $this->trxStatus = self::STATUS_TRX_ERROR;
3758                         $this->trxStatusCause = new DBUnexpectedError(
3759                                 $this,
3760                                 "Uncancelable atomic section canceled (got $fname)."
3761                         );
3762                 }
3763
3764                 $this->affectedRowCount = 0; // for the sake of consistency
3765         }
3766
3767         final public function doAtomicSection(
3768                 $fname, callable $callback, $cancelable = self::ATOMIC_NOT_CANCELABLE
3769         ) {
3770                 $sectionId = $this->startAtomic( $fname, $cancelable );
3771                 try {
3772                         $res = $callback( $this, $fname );
3773                 } catch ( Exception $e ) {
3774                         $this->cancelAtomic( $fname, $sectionId );
3775
3776                         throw $e;
3777                 }
3778                 $this->endAtomic( $fname );
3779
3780                 return $res;
3781         }
3782
3783         final public function begin( $fname = __METHOD__, $mode = self::TRANSACTION_EXPLICIT ) {
3784                 static $modes = [ self::TRANSACTION_EXPLICIT, self::TRANSACTION_INTERNAL ];
3785                 if ( !in_array( $mode, $modes, true ) ) {
3786                         throw new DBUnexpectedError( $this, "$fname: invalid mode parameter '$mode'." );
3787                 }
3788
3789                 // Protect against mismatched atomic section, transaction nesting, and snapshot loss
3790                 if ( $this->trxLevel ) {
3791                         if ( $this->trxAtomicLevels ) {
3792                                 $levels = $this->flatAtomicSectionList();
3793                                 $msg = "$fname: Got explicit BEGIN while atomic section(s) $levels are open.";
3794                                 throw new DBUnexpectedError( $this, $msg );
3795                         } elseif ( !$this->trxAutomatic ) {
3796                                 $msg = "$fname: Explicit transaction already active (from {$this->trxFname}).";
3797                                 throw new DBUnexpectedError( $this, $msg );
3798                         } else {
3799                                 $msg = "$fname: Implicit transaction already active (from {$this->trxFname}).";
3800                                 throw new DBUnexpectedError( $this, $msg );
3801                         }
3802                 } elseif ( $this->getFlag( self::DBO_TRX ) && $mode !== self::TRANSACTION_INTERNAL ) {
3803                         $msg = "$fname: Implicit transaction expected (DBO_TRX set).";
3804                         throw new DBUnexpectedError( $this, $msg );
3805                 }
3806
3807                 // Avoid fatals if close() was called
3808                 $this->assertOpen();
3809
3810                 $this->doBegin( $fname );
3811                 $this->trxStatus = self::STATUS_TRX_OK;
3812                 $this->trxStatusIgnoredCause = null;
3813                 $this->trxAtomicCounter = 0;
3814                 $this->trxTimestamp = microtime( true );
3815                 $this->trxFname = $fname;
3816                 $this->trxDoneWrites = false;
3817                 $this->trxAutomaticAtomic = false;
3818                 $this->trxAtomicLevels = [];
3819                 $this->trxShortId = sprintf( '%06x', mt_rand( 0, 0xffffff ) );
3820                 $this->trxWriteDuration = 0.0;
3821                 $this->trxWriteQueryCount = 0;
3822                 $this->trxWriteAffectedRows = 0;
3823                 $this->trxWriteAdjDuration = 0.0;
3824                 $this->trxWriteAdjQueryCount = 0;
3825                 $this->trxWriteCallers = [];
3826                 // First SELECT after BEGIN will establish the snapshot in REPEATABLE-READ.
3827                 // Get an estimate of the replication lag before any such queries.
3828                 $this->trxReplicaLag = null; // clear cached value first
3829                 $this->trxReplicaLag = $this->getApproximateLagStatus()['lag'];
3830                 // T147697: make explicitTrxActive() return true until begin() finishes. This way, no
3831                 // caller will think its OK to muck around with the transaction just because startAtomic()
3832                 // has not yet completed (e.g. setting trxAtomicLevels).
3833                 $this->trxAutomatic = ( $mode === self::TRANSACTION_INTERNAL );
3834         }
3835
3836         /**
3837          * Issues the BEGIN command to the database server.
3838          *
3839          * @see Database::begin()
3840          * @param string $fname
3841          */
3842         protected function doBegin( $fname ) {
3843                 $this->query( 'BEGIN', $fname );
3844                 $this->trxLevel = 1;
3845         }
3846
3847         final public function commit( $fname = __METHOD__, $flush = self::FLUSHING_ONE ) {
3848                 static $modes = [ self::FLUSHING_ONE, self::FLUSHING_ALL_PEERS, self::FLUSHING_INTERNAL ];
3849                 if ( !in_array( $flush, $modes, true ) ) {
3850                         throw new DBUnexpectedError( $this, "$fname: invalid flush parameter '$flush'." );
3851                 }
3852
3853                 if ( $this->trxLevel && $this->trxAtomicLevels ) {
3854                         // There are still atomic sections open; this cannot be ignored
3855                         $levels = $this->flatAtomicSectionList();
3856                         throw new DBUnexpectedError(
3857                                 $this,
3858                                 "$fname: Got COMMIT while atomic sections $levels are still open."
3859                         );
3860                 }
3861
3862                 if ( $flush === self::FLUSHING_INTERNAL || $flush === self::FLUSHING_ALL_PEERS ) {
3863                         if ( !$this->trxLevel ) {
3864                                 return; // nothing to do
3865                         } elseif ( !$this->trxAutomatic ) {
3866                                 throw new DBUnexpectedError(
3867                                         $this,
3868                                         "$fname: Flushing an explicit transaction, getting out of sync."
3869                                 );
3870                         }
3871                 } else {
3872                         if ( !$this->trxLevel ) {
3873                                 $this->queryLogger->error(
3874                                         "$fname: No transaction to commit, something got out of sync." );
3875                                 return; // nothing to do
3876                         } elseif ( $this->trxAutomatic ) {
3877                                 throw new DBUnexpectedError(
3878                                         $this,
3879                                         "$fname: Expected mass commit of all peer transactions (DBO_TRX set)."
3880                                 );
3881                         }
3882                 }
3883
3884                 // Avoid fatals if close() was called
3885                 $this->assertOpen();
3886
3887                 $this->runOnTransactionPreCommitCallbacks();
3888
3889                 $writeTime = $this->pendingWriteQueryDuration( self::ESTIMATE_DB_APPLY );
3890                 $this->doCommit( $fname );
3891                 $this->trxStatus = self::STATUS_TRX_NONE;
3892
3893                 if ( $this->trxDoneWrites ) {
3894                         $this->lastWriteTime = microtime( true );
3895                         $this->trxProfiler->transactionWritingOut(
3896                                 $this->server,
3897                                 $this->getDomainID(),
3898                                 $this->trxShortId,
3899                                 $writeTime,
3900                                 $this->trxWriteAffectedRows
3901                         );
3902                 }
3903
3904                 // With FLUSHING_ALL_PEERS, callbacks will be explicitly run later
3905                 if ( $flush !== self::FLUSHING_ALL_PEERS ) {
3906                         $this->runOnTransactionIdleCallbacks( self::TRIGGER_COMMIT );
3907                         $this->runTransactionListenerCallbacks( self::TRIGGER_COMMIT );
3908                 }
3909         }
3910
3911         /**
3912          * Issues the COMMIT command to the database server.
3913          *
3914          * @see Database::commit()
3915          * @param string $fname
3916          */
3917         protected function doCommit( $fname ) {
3918                 if ( $this->trxLevel ) {
3919                         $this->query( 'COMMIT', $fname );
3920                         $this->trxLevel = 0;
3921                 }
3922         }
3923
3924         final public function rollback( $fname = __METHOD__, $flush = '' ) {
3925                 $trxActive = $this->trxLevel;
3926
3927                 if ( $flush !== self::FLUSHING_INTERNAL && $flush !== self::FLUSHING_ALL_PEERS ) {
3928                         if ( $this->getFlag( self::DBO_TRX ) ) {
3929                                 throw new DBUnexpectedError(
3930                                         $this,
3931                                         "$fname: Expected mass rollback of all peer transactions (DBO_TRX set)."
3932                                 );
3933                         }
3934                 }
3935
3936                 if ( $trxActive ) {
3937                         // Avoid fatals if close() was called
3938                         $this->assertOpen();
3939
3940                         $writeTime = $this->pendingWriteQueryDuration( self::ESTIMATE_DB_APPLY );
3941                         $this->doRollback( $fname );
3942                         $this->trxStatus = self::STATUS_TRX_NONE;
3943                         $this->trxAtomicLevels = [];
3944
3945                         if ( $this->trxDoneWrites ) {
3946                                 $this->trxProfiler->transactionWritingOut(
3947                                         $this->server,
3948                                         $this->getDomainID(),
3949                                         $this->trxShortId,
3950                                         $writeTime,
3951                                         $this->trxWriteAffectedRows
3952                                 );
3953                         }
3954                 }
3955
3956                 // Clear any commit-dependant callbacks. They might even be present
3957                 // only due to transaction rounds, with no SQL transaction being active
3958                 $this->trxIdleCallbacks = [];
3959                 $this->trxPreCommitCallbacks = [];
3960
3961                 // With FLUSHING_ALL_PEERS, callbacks will be explicitly run later
3962                 if ( $trxActive && $flush !== self::FLUSHING_ALL_PEERS ) {
3963                         try {
3964                                 $this->runOnTransactionIdleCallbacks( self::TRIGGER_ROLLBACK );
3965                         } catch ( Exception $e ) {
3966                                 // already logged; finish and let LoadBalancer move on during mass-rollback
3967                         }
3968                         try {
3969                                 $this->runTransactionListenerCallbacks( self::TRIGGER_ROLLBACK );
3970                         } catch ( Exception $e ) {
3971                                 // already logged; let LoadBalancer move on during mass-rollback
3972                         }
3973
3974                         $this->affectedRowCount = 0; // for the sake of consistency
3975                 }
3976         }
3977
3978         /**
3979          * Issues the ROLLBACK command to the database server.
3980          *
3981          * @see Database::rollback()
3982          * @param string $fname
3983          */
3984         protected function doRollback( $fname ) {
3985                 if ( $this->trxLevel ) {
3986                         # Disconnects cause rollback anyway, so ignore those errors
3987                         $ignoreErrors = true;
3988                         $this->query( 'ROLLBACK', $fname, $ignoreErrors );
3989                         $this->trxLevel = 0;
3990                 }
3991         }
3992
3993         public function flushSnapshot( $fname = __METHOD__ ) {
3994                 if ( $this->writesOrCallbacksPending() || $this->explicitTrxActive() ) {
3995                         // This only flushes transactions to clear snapshots, not to write data
3996                         $fnames = implode( ', ', $this->pendingWriteAndCallbackCallers() );
3997                         throw new DBUnexpectedError(
3998                                 $this,
3999                                 "$fname: Cannot flush snapshot because writes are pending ($fnames)."
4000                         );
4001                 }
4002
4003                 $this->commit( $fname, self::FLUSHING_INTERNAL );
4004         }
4005
4006         public function explicitTrxActive() {
4007                 return $this->trxLevel && ( $this->trxAtomicLevels || !$this->trxAutomatic );
4008         }
4009
4010         public function duplicateTableStructure(
4011                 $oldName, $newName, $temporary = false, $fname = __METHOD__
4012         ) {
4013                 throw new RuntimeException( __METHOD__ . ' is not implemented in descendant class' );
4014         }
4015
4016         public function listTables( $prefix = null, $fname = __METHOD__ ) {
4017                 throw new RuntimeException( __METHOD__ . ' is not implemented in descendant class' );
4018         }
4019
4020         public function listViews( $prefix = null, $fname = __METHOD__ ) {
4021                 throw new RuntimeException( __METHOD__ . ' is not implemented in descendant class' );
4022         }
4023
4024         public function timestamp( $ts = 0 ) {
4025                 $t = new ConvertibleTimestamp( $ts );
4026                 // Let errors bubble up to avoid putting garbage in the DB
4027                 return $t->getTimestamp( TS_MW );
4028         }
4029
4030         public function timestampOrNull( $ts = null ) {
4031                 if ( is_null( $ts ) ) {
4032                         return null;
4033                 } else {
4034                         return $this->timestamp( $ts );
4035                 }
4036         }
4037
4038         public function affectedRows() {
4039                 return ( $this->affectedRowCount === null )
4040                         ? $this->fetchAffectedRowCount() // default to driver value
4041                         : $this->affectedRowCount;
4042         }
4043
4044         /**
4045          * @return int Number of retrieved rows according to the driver
4046          */
4047         abstract protected function fetchAffectedRowCount();
4048
4049         /**
4050          * Take the result from a query, and wrap it in a ResultWrapper if
4051          * necessary. Boolean values are passed through as is, to indicate success
4052          * of write queries or failure.
4053          *
4054          * Once upon a time, Database::query() returned a bare MySQL result
4055          * resource, and it was necessary to call this function to convert it to
4056          * a wrapper. Nowadays, raw database objects are never exposed to external
4057          * callers, so this is unnecessary in external code.
4058          *
4059          * @param bool|ResultWrapper|resource $result
4060          * @return bool|ResultWrapper
4061          */
4062         protected function resultObject( $result ) {
4063                 if ( !$result ) {
4064                         return false;
4065                 } elseif ( $result instanceof ResultWrapper ) {
4066                         return $result;
4067                 } elseif ( $result === true ) {
4068                         // Successful write query
4069                         return $result;
4070                 } else {
4071                         return new ResultWrapper( $this, $result );
4072                 }
4073         }
4074
4075         public function ping( &$rtt = null ) {
4076                 // Avoid hitting the server if it was hit recently
4077                 if ( $this->isOpen() && ( microtime( true ) - $this->lastPing ) < self::PING_TTL ) {
4078                         if ( !func_num_args() || $this->rttEstimate > 0 ) {
4079                                 $rtt = $this->rttEstimate;
4080                                 return true; // don't care about $rtt
4081                         }
4082                 }
4083
4084                 // This will reconnect if possible or return false if not
4085                 $this->clearFlag( self::DBO_TRX, self::REMEMBER_PRIOR );
4086                 $ok = ( $this->query( self::PING_QUERY, __METHOD__, true ) !== false );
4087                 $this->restoreFlags( self::RESTORE_PRIOR );
4088
4089                 if ( $ok ) {
4090                         $rtt = $this->rttEstimate;
4091                 }
4092
4093                 return $ok;
4094         }
4095
4096         /**
4097          * Close any existing (dead) database connection and open a new connection
4098          *
4099          * @param string $fname
4100          * @return bool True if new connection is opened successfully, false if error
4101          */
4102         protected function replaceLostConnection( $fname ) {
4103                 $this->closeConnection();
4104                 $this->opened = false;
4105                 $this->conn = false;
4106                 try {
4107                         $this->open( $this->server, $this->user, $this->password, $this->dbName );
4108                         $this->lastPing = microtime( true );
4109                         $ok = true;
4110
4111                         $this->connLogger->warning(
4112                                 $fname . ': lost connection to {dbserver}; reconnected',
4113                                 [
4114                                         'dbserver' => $this->getServer(),
4115                                         'trace' => ( new RuntimeException() )->getTraceAsString()
4116                                 ]
4117                         );
4118                 } catch ( DBConnectionError $e ) {
4119                         $ok = false;
4120
4121                         $this->connLogger->error(
4122                                 $fname . ': lost connection to {dbserver} permanently',
4123                                 [ 'dbserver' => $this->getServer() ]
4124                         );
4125                 }
4126
4127                 $this->handleSessionLoss();
4128
4129                 return $ok;
4130         }
4131
4132         public function getSessionLagStatus() {
4133                 return $this->getRecordedTransactionLagStatus() ?: $this->getApproximateLagStatus();
4134         }
4135
4136         /**
4137          * Get the replica DB lag when the current transaction started
4138          *
4139          * This is useful when transactions might use snapshot isolation
4140          * (e.g. REPEATABLE-READ in innodb), so the "real" lag of that data
4141          * is this lag plus transaction duration. If they don't, it is still
4142          * safe to be pessimistic. This returns null if there is no transaction.
4143          *
4144          * This returns null if the lag status for this transaction was not yet recorded.
4145          *
4146          * @return array|null ('lag': seconds or false on error, 'since': UNIX timestamp of BEGIN)
4147          * @since 1.27
4148          */
4149         final protected function getRecordedTransactionLagStatus() {
4150                 return ( $this->trxLevel && $this->trxReplicaLag !== null )
4151                         ? [ 'lag' => $this->trxReplicaLag, 'since' => $this->trxTimestamp() ]
4152                         : null;
4153         }
4154
4155         /**
4156          * Get a replica DB lag estimate for this server
4157          *
4158          * @return array ('lag': seconds or false on error, 'since': UNIX timestamp of estimate)
4159          * @since 1.27
4160          */
4161         protected function getApproximateLagStatus() {
4162                 return [
4163                         'lag'   => $this->getLBInfo( 'replica' ) ? $this->getLag() : 0,
4164                         'since' => microtime( true )
4165                 ];
4166         }
4167
4168         /**
4169          * Merge the result of getSessionLagStatus() for several DBs
4170          * using the most pessimistic values to estimate the lag of
4171          * any data derived from them in combination
4172          *
4173          * This is information is useful for caching modules
4174          *
4175          * @see WANObjectCache::set()
4176          * @see WANObjectCache::getWithSetCallback()
4177          *
4178          * @param IDatabase $db1
4179          * @param IDatabase|null $db2 [optional]
4180          * @return array Map of values:
4181          *   - lag: highest lag of any of the DBs or false on error (e.g. replication stopped)
4182          *   - since: oldest UNIX timestamp of any of the DB lag estimates
4183          *   - pending: whether any of the DBs have uncommitted changes
4184          * @throws DBError
4185          * @since 1.27
4186          */
4187         public static function getCacheSetOptions( IDatabase $db1, IDatabase $db2 = null ) {
4188                 $res = [ 'lag' => 0, 'since' => INF, 'pending' => false ];
4189                 foreach ( func_get_args() as $db ) {
4190                         /** @var IDatabase $db */
4191                         $status = $db->getSessionLagStatus();
4192                         if ( $status['lag'] === false ) {
4193                                 $res['lag'] = false;
4194                         } elseif ( $res['lag'] !== false ) {
4195                                 $res['lag'] = max( $res['lag'], $status['lag'] );
4196                         }
4197                         $res['since'] = min( $res['since'], $status['since'] );
4198                         $res['pending'] = $res['pending'] ?: $db->writesPending();
4199                 }
4200
4201                 return $res;
4202         }
4203
4204         public function getLag() {
4205                 return 0;
4206         }
4207
4208         public function maxListLen() {
4209                 return 0;
4210         }
4211
4212         public function encodeBlob( $b ) {
4213                 return $b;
4214         }
4215
4216         public function decodeBlob( $b ) {
4217                 if ( $b instanceof Blob ) {
4218                         $b = $b->fetch();
4219                 }
4220                 return $b;
4221         }
4222
4223         public function setSessionOptions( array $options ) {
4224         }
4225
4226         public function sourceFile(
4227                 $filename,
4228                 callable $lineCallback = null,
4229                 callable $resultCallback = null,
4230                 $fname = false,
4231                 callable $inputCallback = null
4232         ) {
4233                 Wikimedia\suppressWarnings();
4234                 $fp = fopen( $filename, 'r' );
4235                 Wikimedia\restoreWarnings();
4236
4237                 if ( false === $fp ) {
4238                         throw new RuntimeException( "Could not open \"{$filename}\".\n" );
4239                 }
4240
4241                 if ( !$fname ) {
4242                         $fname = __METHOD__ . "( $filename )";
4243                 }
4244
4245                 try {
4246                         $error = $this->sourceStream(
4247                                 $fp, $lineCallback, $resultCallback, $fname, $inputCallback );
4248                 } catch ( Exception $e ) {
4249                         fclose( $fp );
4250                         throw $e;
4251                 }
4252
4253                 fclose( $fp );
4254
4255                 return $error;
4256         }
4257
4258         public function setSchemaVars( $vars ) {
4259                 $this->schemaVars = $vars;
4260         }
4261
4262         public function sourceStream(
4263                 $fp,
4264                 callable $lineCallback = null,
4265                 callable $resultCallback = null,
4266                 $fname = __METHOD__,
4267                 callable $inputCallback = null
4268         ) {
4269                 $delimiterReset = new ScopedCallback(
4270                         function ( $delimiter ) {
4271                                 $this->delimiter = $delimiter;
4272                         },
4273                         [ $this->delimiter ]
4274                 );
4275                 $cmd = '';
4276
4277                 while ( !feof( $fp ) ) {
4278                         if ( $lineCallback ) {
4279                                 call_user_func( $lineCallback );
4280                         }
4281
4282                         $line = trim( fgets( $fp ) );
4283
4284                         if ( $line == '' ) {
4285                                 continue;
4286                         }
4287
4288                         if ( '-' == $line[0] && '-' == $line[1] ) {
4289                                 continue;
4290                         }
4291
4292                         if ( $cmd != '' ) {
4293                                 $cmd .= ' ';
4294                         }
4295
4296                         $done = $this->streamStatementEnd( $cmd, $line );
4297
4298                         $cmd .= "$line\n";
4299
4300                         if ( $done || feof( $fp ) ) {
4301                                 $cmd = $this->replaceVars( $cmd );
4302
4303                                 if ( $inputCallback ) {
4304                                         $callbackResult = $inputCallback( $cmd );
4305
4306                                         if ( is_string( $callbackResult ) || !$callbackResult ) {
4307                                                 $cmd = $callbackResult;
4308                                         }
4309                                 }
4310
4311                                 if ( $cmd ) {
4312                                         $res = $this->query( $cmd, $fname );
4313
4314                                         if ( $resultCallback ) {
4315                                                 $resultCallback( $res, $this );
4316                                         }
4317
4318                                         if ( false === $res ) {
4319                                                 $err = $this->lastError();
4320
4321                                                 return "Query \"{$cmd}\" failed with error code \"$err\".\n";
4322                                         }
4323                                 }
4324                                 $cmd = '';
4325                         }
4326                 }
4327
4328                 ScopedCallback::consume( $delimiterReset );
4329                 return true;
4330         }
4331
4332         /**
4333          * Called by sourceStream() to check if we've reached a statement end
4334          *
4335          * @param string &$sql SQL assembled so far
4336          * @param string &$newLine New line about to be added to $sql
4337          * @return bool Whether $newLine contains end of the statement
4338          */
4339         public function streamStatementEnd( &$sql, &$newLine ) {
4340                 if ( $this->delimiter ) {
4341                         $prev = $newLine;
4342                         $newLine = preg_replace(
4343                                 '/' . preg_quote( $this->delimiter, '/' ) . '$/', '', $newLine );
4344                         if ( $newLine != $prev ) {
4345                                 return true;
4346                         }
4347                 }
4348
4349                 return false;
4350         }
4351
4352         /**
4353          * Database independent variable replacement. Replaces a set of variables
4354          * in an SQL statement with their contents as given by $this->getSchemaVars().
4355          *
4356          * Supports '{$var}' `{$var}` and / *$var* / (without the spaces) style variables.
4357          *
4358          * - '{$var}' should be used for text and is passed through the database's
4359          *   addQuotes method.
4360          * - `{$var}` should be used for identifiers (e.g. table and database names).
4361          *   It is passed through the database's addIdentifierQuotes method which
4362          *   can be overridden if the database uses something other than backticks.
4363          * - / *_* / or / *$wgDBprefix* / passes the name that follows through the
4364          *   database's tableName method.
4365          * - / *i* / passes the name that follows through the database's indexName method.
4366          * - In all other cases, / *$var* / is left unencoded. Except for table options,
4367          *   its use should be avoided. In 1.24 and older, string encoding was applied.
4368          *
4369          * @param string $ins SQL statement to replace variables in
4370          * @return string The new SQL statement with variables replaced
4371          */
4372         protected function replaceVars( $ins ) {
4373                 $vars = $this->getSchemaVars();
4374                 return preg_replace_callback(
4375                         '!
4376                                 /\* (\$wgDBprefix|[_i]) \*/ (\w*) | # 1-2. tableName, indexName
4377                                 \'\{\$ (\w+) }\'                  | # 3. addQuotes
4378                                 `\{\$ (\w+) }`                    | # 4. addIdentifierQuotes
4379                                 /\*\$ (\w+) \*/                     # 5. leave unencoded
4380                         !x',
4381                         function ( $m ) use ( $vars ) {
4382                                 // Note: Because of <https://bugs.php.net/bug.php?id=51881>,
4383                                 // check for both nonexistent keys *and* the empty string.
4384                                 if ( isset( $m[1] ) && $m[1] !== '' ) {
4385                                         if ( $m[1] === 'i' ) {
4386                                                 return $this->indexName( $m[2] );
4387                                         } else {
4388                                                 return $this->tableName( $m[2] );
4389                                         }
4390                                 } elseif ( isset( $m[3] ) && $m[3] !== '' && array_key_exists( $m[3], $vars ) ) {
4391                                         return $this->addQuotes( $vars[$m[3]] );
4392                                 } elseif ( isset( $m[4] ) && $m[4] !== '' && array_key_exists( $m[4], $vars ) ) {
4393                                         return $this->addIdentifierQuotes( $vars[$m[4]] );
4394                                 } elseif ( isset( $m[5] ) && $m[5] !== '' && array_key_exists( $m[5], $vars ) ) {
4395                                         return $vars[$m[5]];
4396                                 } else {
4397                                         return $m[0];
4398                                 }
4399                         },
4400                         $ins
4401                 );
4402         }
4403
4404         /**
4405          * Get schema variables. If none have been set via setSchemaVars(), then
4406          * use some defaults from the current object.
4407          *
4408          * @return array
4409          */
4410         protected function getSchemaVars() {
4411                 if ( $this->schemaVars ) {
4412                         return $this->schemaVars;
4413                 } else {
4414                         return $this->getDefaultSchemaVars();
4415                 }
4416         }
4417
4418         /**
4419          * Get schema variables to use if none have been set via setSchemaVars().
4420          *
4421          * Override this in derived classes to provide variables for tables.sql
4422          * and SQL patch files.
4423          *
4424          * @return array
4425          */
4426         protected function getDefaultSchemaVars() {
4427                 return [];
4428         }
4429
4430         public function lockIsFree( $lockName, $method ) {
4431                 // RDBMs methods for checking named locks may or may not count this thread itself.
4432                 // In MySQL, IS_FREE_LOCK() returns 0 if the thread already has the lock. This is
4433                 // the behavior choosen by the interface for this method.
4434                 return !isset( $this->namedLocksHeld[$lockName] );
4435         }
4436
4437         public function lock( $lockName, $method, $timeout = 5 ) {
4438                 $this->namedLocksHeld[$lockName] = 1;
4439
4440                 return true;
4441         }
4442
4443         public function unlock( $lockName, $method ) {
4444                 unset( $this->namedLocksHeld[$lockName] );
4445
4446                 return true;
4447         }
4448
4449         public function getScopedLockAndFlush( $lockKey, $fname, $timeout ) {
4450                 if ( $this->writesOrCallbacksPending() ) {
4451                         // This only flushes transactions to clear snapshots, not to write data
4452                         $fnames = implode( ', ', $this->pendingWriteAndCallbackCallers() );
4453                         throw new DBUnexpectedError(
4454                                 $this,
4455                                 "$fname: Cannot flush pre-lock snapshot because writes are pending ($fnames)."
4456                         );
4457                 }
4458
4459                 if ( !$this->lock( $lockKey, $fname, $timeout ) ) {
4460                         return null;
4461                 }
4462
4463                 $unlocker = new ScopedCallback( function () use ( $lockKey, $fname ) {
4464                         if ( $this->trxLevel() ) {
4465                                 // There is a good chance an exception was thrown, causing any early return
4466                                 // from the caller. Let any error handler get a chance to issue rollback().
4467                                 // If there isn't one, let the error bubble up and trigger server-side rollback.
4468                                 $this->onTransactionResolution(
4469                                         function () use ( $lockKey, $fname ) {
4470                                                 $this->unlock( $lockKey, $fname );
4471                                         },
4472                                         $fname
4473                                 );
4474                         } else {
4475                                 $this->unlock( $lockKey, $fname );
4476                         }
4477                 } );
4478
4479                 $this->commit( $fname, self::FLUSHING_INTERNAL );
4480
4481                 return $unlocker;
4482         }
4483
4484         public function namedLocksEnqueue() {
4485                 return false;
4486         }
4487
4488         public function tableLocksHaveTransactionScope() {
4489                 return true;
4490         }
4491
4492         final public function lockTables( array $read, array $write, $method ) {
4493                 if ( $this->writesOrCallbacksPending() ) {
4494                         throw new DBUnexpectedError( $this, "Transaction writes or callbacks still pending." );
4495                 }
4496
4497                 if ( $this->tableLocksHaveTransactionScope() ) {
4498                         $this->startAtomic( $method );
4499                 }
4500
4501                 return $this->doLockTables( $read, $write, $method );
4502         }
4503
4504         /**
4505          * Helper function for lockTables() that handles the actual table locking
4506          *
4507          * @param array $read Array of tables to lock for read access
4508          * @param array $write Array of tables to lock for write access
4509          * @param string $method Name of caller
4510          * @return true
4511          */
4512         protected function doLockTables( array $read, array $write, $method ) {
4513                 return true;
4514         }
4515
4516         final public function unlockTables( $method ) {
4517                 if ( $this->tableLocksHaveTransactionScope() ) {
4518                         $this->endAtomic( $method );
4519
4520                         return true; // locks released on COMMIT/ROLLBACK
4521                 }
4522
4523                 return $this->doUnlockTables( $method );
4524         }
4525
4526         /**
4527          * Helper function for unlockTables() that handles the actual table unlocking
4528          *
4529          * @param string $method Name of caller
4530          * @return true
4531          */
4532         protected function doUnlockTables( $method ) {
4533                 return true;
4534         }
4535
4536         /**
4537          * Delete a table
4538          * @param string $tableName
4539          * @param string $fName
4540          * @return bool|ResultWrapper
4541          * @since 1.18
4542          */
4543         public function dropTable( $tableName, $fName = __METHOD__ ) {
4544                 if ( !$this->tableExists( $tableName, $fName ) ) {
4545                         return false;
4546                 }
4547                 $sql = "DROP TABLE " . $this->tableName( $tableName ) . " CASCADE";
4548
4549                 return $this->query( $sql, $fName );
4550         }
4551
4552         public function getInfinity() {
4553                 return 'infinity';
4554         }
4555
4556         public function encodeExpiry( $expiry ) {
4557                 return ( $expiry == '' || $expiry == 'infinity' || $expiry == $this->getInfinity() )
4558                         ? $this->getInfinity()
4559                         : $this->timestamp( $expiry );
4560         }
4561
4562         public function decodeExpiry( $expiry, $format = TS_MW ) {
4563                 if ( $expiry == '' || $expiry == 'infinity' || $expiry == $this->getInfinity() ) {
4564                         return 'infinity';
4565                 }
4566
4567                 return ConvertibleTimestamp::convert( $format, $expiry );
4568         }
4569
4570         public function setBigSelects( $value = true ) {
4571                 // no-op
4572         }
4573
4574         public function isReadOnly() {
4575                 return ( $this->getReadOnlyReason() !== false );
4576         }
4577
4578         /**
4579          * @return string|bool Reason this DB is read-only or false if it is not
4580          */
4581         protected function getReadOnlyReason() {
4582                 $reason = $this->getLBInfo( 'readOnlyReason' );
4583
4584                 return is_string( $reason ) ? $reason : false;
4585         }
4586
4587         public function setTableAliases( array $aliases ) {
4588                 $this->tableAliases = $aliases;
4589         }
4590
4591         public function setIndexAliases( array $aliases ) {
4592                 $this->indexAliases = $aliases;
4593         }
4594
4595         /**
4596          * Get the underlying binding connection handle
4597          *
4598          * Makes sure the connection resource is set (disconnects and ping() failure can unset it).
4599          * This catches broken callers than catch and ignore disconnection exceptions.
4600          * Unlike checking isOpen(), this is safe to call inside of open().
4601          *
4602          * @return mixed
4603          * @throws DBUnexpectedError
4604          * @since 1.26
4605          */
4606         protected function getBindingHandle() {
4607                 if ( !$this->conn ) {
4608                         throw new DBUnexpectedError(
4609                                 $this,
4610                                 'DB connection was already closed or the connection dropped.'
4611                         );
4612                 }
4613
4614                 return $this->conn;
4615         }
4616
4617         /**
4618          * @since 1.19
4619          * @return string
4620          */
4621         public function __toString() {
4622                 return (string)$this->conn;
4623         }
4624
4625         /**
4626          * Make sure that copies do not share the same client binding handle
4627          * @throws DBConnectionError
4628          */
4629         public function __clone() {
4630                 $this->connLogger->warning(
4631                         "Cloning " . static::class . " is not recommended; forking connection:\n" .
4632                         ( new RuntimeException() )->getTraceAsString()
4633                 );
4634
4635                 if ( $this->isOpen() ) {
4636                         // Open a new connection resource without messing with the old one
4637                         $this->opened = false;
4638                         $this->conn = false;
4639                         $this->trxEndCallbacks = []; // don't copy
4640                         $this->handleSessionLoss(); // no trx or locks anymore
4641                         $this->open( $this->server, $this->user, $this->password, $this->dbName );
4642                         $this->lastPing = microtime( true );
4643                 }
4644         }
4645
4646         /**
4647          * Called by serialize. Throw an exception when DB connection is serialized.
4648          * This causes problems on some database engines because the connection is
4649          * not restored on unserialize.
4650          */
4651         public function __sleep() {
4652                 throw new RuntimeException( 'Database serialization may cause problems, since ' .
4653                         'the connection is not restored on wakeup.' );
4654         }
4655
4656         /**
4657          * Run a few simple sanity checks and close dangling connections
4658          */
4659         public function __destruct() {
4660                 if ( $this->trxLevel && $this->trxDoneWrites ) {
4661                         trigger_error( "Uncommitted DB writes (transaction from {$this->trxFname})." );
4662                 }
4663
4664                 $danglingWriters = $this->pendingWriteAndCallbackCallers();
4665                 if ( $danglingWriters ) {
4666                         $fnames = implode( ', ', $danglingWriters );
4667                         trigger_error( "DB transaction writes or callbacks still pending ($fnames)." );
4668                 }
4669
4670                 if ( $this->conn ) {
4671                         // Avoid connection leaks for sanity. Normally, resources close at script completion.
4672                         // The connection might already be closed in zend/hhvm by now, so suppress warnings.
4673                         Wikimedia\suppressWarnings();
4674                         $this->closeConnection();
4675                         Wikimedia\restoreWarnings();
4676                         $this->conn = false;
4677                         $this->opened = false;
4678                 }
4679         }
4680 }
4681
4682 /**
4683  * @deprecated since 1.28
4684  */
4685 class_alias( Database::class, 'DatabaseBase' );
4686
4687 /**
4688  * @deprecated since 1.29
4689  */
4690 class_alias( Database::class, 'Database' );