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 Wikimedia\ScopedCallback;
  31 use Wikimedia\Timestamp\ConvertibleTimestamp;
  32 use Wikimedia;
  33 use BagOStuff;
  34 use HashBagOStuff;
  35 use InvalidArgumentException;
  36 use Exception;
  37 use RuntimeException;
  38
  39 /**
  40  * Relational database abstraction object
  41  *
  42  * @ingroup Database
  43  * @since 1.28
  44  */
  45 abstract class Database implements IDatabase, IMaintainableDatabase, LoggerAwareInterface {
  46         /** Number of times to re-try an operation in case of deadlock */
  47         const DEADLOCK_TRIES = 4;
  48         /** Minimum time to wait before retry, in microseconds */
  49         const DEADLOCK_DELAY_MIN = 500000;
  50         /** Maximum time to wait before retry */
  51         const DEADLOCK_DELAY_MAX = 1500000;
  52
  53         /** How long before it is worth doing a dummy query to test the connection */
  54         const PING_TTL = 1.0;
  55         const PING_QUERY = 'SELECT 1 AS ping';
  56
  57         const TINY_WRITE_SEC = 0.010;
  58         const SLOW_WRITE_SEC = 0.500;
  59         const SMALL_WRITE_ROWS = 100;
  60
  61         /** @var string SQL query */
  62         protected $lastQuery = '';
  63         /** @var float|bool UNIX timestamp of last write query */
  64         protected $lastWriteTime = false;
  65         /** @var string|bool */
  66         protected $phpError = false;
  67         /** @var string */
  68         protected $server;
  69         /** @var string */
  70         protected $user;
  71         /** @var string */
  72         protected $password;
  73         /** @var string */
  74         protected $dbName;
  75         /** @var array[] $aliases Map of (table => (dbname, schema, prefix) map) */
  76         protected $tableAliases = [];
  77         /** @var bool Whether this PHP instance is for a CLI script */
  78         protected $cliMode;
  79         /** @var string Agent name for query profiling */
  80         protected $agent;
  81
  82         /** @var BagOStuff APC cache */
  83         protected $srvCache;
  84         /** @var LoggerInterface */
  85         protected $connLogger;
  86         /** @var LoggerInterface */
  87         protected $queryLogger;
  88         /** @var callback Error logging callback */
  89         protected $errorLogger;
  90
  91         /** @var resource|null Database connection */
  92         protected $conn = null;
  93         /** @var bool */
  94         protected $opened = false;
  95
  96         /** @var array[] List of (callable, method name) */
  97         protected $trxIdleCallbacks = [];
  98         /** @var array[] List of (callable, method name) */
  99         protected $trxPreCommitCallbacks = [];
 100         /** @var array[] List of (callable, method name) */
 101         protected $trxEndCallbacks = [];
 102         /** @var callable[] Map of (name => callable) */
 103         protected $trxRecurringCallbacks = [];
 104         /** @var bool Whether to suppress triggering of transaction end callbacks */
 105         protected $trxEndCallbacksSuppressed = false;
 106
 107         /** @var string */
 108         protected $tablePrefix = '';
 109         /** @var string */
 110         protected $schema = '';
 111         /** @var int */
 112         protected $flags;
 113         /** @var array */
 114         protected $lbInfo = [];
 115         /** @var array|bool */
 116         protected $schemaVars = false;
 117         /** @var array */
 118         protected $sessionVars = [];
 119         /** @var array|null */
 120         protected $preparedArgs;
 121         /** @var string|bool|null Stashed value of html_errors INI setting */
 122         protected $htmlErrors;
 123         /** @var string */
 124         protected $delimiter = ';';
 125         /** @var DatabaseDomain */
 126         protected $currentDomain;
 127         /** @var integer|null Rows affected by the last query to query() or its CRUD wrappers */
 128         protected $affectedRowCount;
 129
 130         /**
 131          * Either 1 if a transaction is active or 0 otherwise.
 132          * The other Trx fields may not be meaningfull if this is 0.
 133          *
 134          * @var int
 135          */
 136         protected $trxLevel = 0;
 137         /**
 138          * Either a short hexidecimal string if a transaction is active or ""
 139          *
 140          * @var string
 141          * @see Database::trxLevel
 142          */
 143         protected $trxShortId = '';
 144         /**
 145          * The UNIX time that the transaction started. Callers can assume that if
 146          * snapshot isolation is used, then the data is *at least* up to date to that
 147          * point (possibly more up-to-date since the first SELECT defines the snapshot).
 148          *
 149          * @var float|null
 150          * @see Database::trxLevel
 151          */
 152         private $trxTimestamp = null;
 153         /** @var float Lag estimate at the time of BEGIN */
 154         private $trxReplicaLag = null;
 155         /**
 156          * Remembers the function name given for starting the most recent transaction via begin().
 157          * Used to provide additional context for error reporting.
 158          *
 159          * @var string
 160          * @see Database::trxLevel
 161          */
 162         private $trxFname = null;
 163         /**
 164          * Record if possible write queries were done in the last transaction started
 165          *
 166          * @var bool
 167          * @see Database::trxLevel
 168          */
 169         private $trxDoneWrites = false;
 170         /**
 171          * Record if the current transaction was started implicitly due to DBO_TRX being set.
 172          *
 173          * @var bool
 174          * @see Database::trxLevel
 175          */
 176         private $trxAutomatic = false;
 177         /**
 178          * Array of levels of atomicity within transactions
 179          *
 180          * @var array
 181          */
 182         private $trxAtomicLevels = [];
 183         /**
 184          * Record if the current transaction was started implicitly by Database::startAtomic
 185          *
 186          * @var bool
 187          */
 188         private $trxAutomaticAtomic = false;
 189         /**
 190          * Track the write query callers of the current transaction
 191          *
 192          * @var string[]
 193          */
 194         private $trxWriteCallers = [];
 195         /**
 196          * @var float Seconds spent in write queries for the current transaction
 197          */
 198         private $trxWriteDuration = 0.0;
 199         /**
 200          * @var int Number of write queries for the current transaction
 201          */
 202         private $trxWriteQueryCount = 0;
 203         /**
 204          * @var int Number of rows affected by write queries for the current transaction
 205          */
 206         private $trxWriteAffectedRows = 0;
 207         /**
 208          * @var float Like trxWriteQueryCount but excludes lock-bound, easy to replicate, queries
 209          */
 210         private $trxWriteAdjDuration = 0.0;
 211         /**
 212          * @var int Number of write queries counted in trxWriteAdjDuration
 213          */
 214         private $trxWriteAdjQueryCount = 0;
 215         /**
 216          * @var float RTT time estimate
 217          */
 218         private $rttEstimate = 0.0;
 219
 220         /** @var array Map of (name => 1) for locks obtained via lock() */
 221         private $namedLocksHeld = [];
 222         /** @var array Map of (table name => 1) for TEMPORARY tables */
 223         protected $sessionTempTables = [];
 224
 225         /** @var IDatabase|null Lazy handle to the master DB this server replicates from */
 226         private $lazyMasterHandle;
 227
 228         /** @var float UNIX timestamp */
 229         protected $lastPing = 0.0;
 230
 231         /** @var int[] Prior flags member variable values */
 232         private $priorFlags = [];
 233
 234         /** @var object|string Class name or object With profileIn/profileOut methods */
 235         protected $profiler;
 236         /** @var TransactionProfiler */
 237         protected $trxProfiler;
 238
 239         /**
 240          * Constructor and database handle and attempt to connect to the DB server
 241          *
 242          * IDatabase classes should not be constructed directly in external
 243          * code. Database::factory() should be used instead.
 244          *
 245          * @param array $params Parameters passed from Database::factory()
 246          */
 247         function __construct( array $params ) {
 248                 $server = $params['host'];
 249                 $user = $params['user'];
 250                 $password = $params['password'];
 251                 $dbName = $params['dbname'];
 252
 253                 $this->schema = $params['schema'];
 254                 $this->tablePrefix = $params['tablePrefix'];
 255
 256                 $this->cliMode = $params['cliMode'];
 257                 // Agent name is added to SQL queries in a comment, so make sure it can't break out
 258                 $this->agent = str_replace( '/', '-', $params['agent'] );
 259
 260                 $this->flags = $params['flags'];
 261                 if ( $this->flags & self::DBO_DEFAULT ) {
 262                         if ( $this->cliMode ) {
 263                                 $this->flags &= ~self::DBO_TRX;
 264                         } else {
 265                                 $this->flags |= self::DBO_TRX;
 266                         }
 267                 }
 268
 269                 $this->sessionVars = $params['variables'];
 270
 271                 $this->srvCache = isset( $params['srvCache'] )
 272                         ? $params['srvCache']
 273                         : new HashBagOStuff();
 274
 275                 $this->profiler = $params['profiler'];
 276                 $this->trxProfiler = $params['trxProfiler'];
 277                 $this->connLogger = $params['connLogger'];
 278                 $this->queryLogger = $params['queryLogger'];
 279                 $this->errorLogger = $params['errorLogger'];
 280
 281                 // Set initial dummy domain until open() sets the final DB/prefix
 282                 $this->currentDomain = DatabaseDomain::newUnspecified();
 283
 284                 if ( $user ) {
 285                         $this->open( $server, $user, $password, $dbName );
 286                 } elseif ( $this->requiresDatabaseUser() ) {
 287                         throw new InvalidArgumentException( "No database user provided." );
 288                 }
 289
 290                 // Set the domain object after open() sets the relevant fields
 291                 if ( $this->dbName != '' ) {
 292                         // Domains with server scope but a table prefix are not used by IDatabase classes
 293                         $this->currentDomain = new DatabaseDomain( $this->dbName, null, $this->tablePrefix );
 294                 }
 295         }
 296
 297         /**
 298          * Construct a Database subclass instance given a database type and parameters
 299          *
 300          * This also connects to the database immediately upon object construction
 301          *
 302          * @param string $dbType A possible DB type (sqlite, mysql, postgres)
 303          * @param array $p Parameter map with keys:
 304          *   - host : The hostname of the DB server
 305          *   - user : The name of the database user the client operates under
 306          *   - password : The password for the database user
 307          *   - dbname : The name of the database to use where queries do not specify one.
 308          *      The database must exist or an error might be thrown. Setting this to the empty string
 309          *      will avoid any such errors and make the handle have no implicit database scope. This is
 310          *      useful for queries like SHOW STATUS, CREATE DATABASE, or DROP DATABASE. Note that a
 311          *      "database" in Postgres is rougly equivalent to an entire MySQL server. This the domain
 312          *      in which user names and such are defined, e.g. users are database-specific in Postgres.
 313          *   - schema : The database schema to use (if supported). A "schema" in Postgres is roughly
 314          *      equivalent to a "database" in MySQL. Note that MySQL and SQLite do not use schemas.
 315          *   - tablePrefix : Optional table prefix that is implicitly added on to all table names
 316          *      recognized in queries. This can be used in place of schemas for handle site farms.
 317          *   - flags : Optional bitfield of DBO_* constants that define connection, protocol,
 318          *      buffering, and transaction behavior. It is STRONGLY adviced to leave the DBO_DEFAULT
 319          *      flag in place UNLESS this this database simply acts as a key/value store.
 320          *   - driver: Optional name of a specific DB client driver. For MySQL, there is only the
 321          *      'mysqli' driver; the old one 'mysql' has been removed.
 322          *   - variables: Optional map of session variables to set after connecting. This can be
 323          *      used to adjust lock timeouts or encoding modes and the like.
 324          *   - connLogger: Optional PSR-3 logger interface instance.
 325          *   - queryLogger: Optional PSR-3 logger interface instance.
 326          *   - profiler: Optional class name or object with profileIn()/profileOut() methods.
 327          *      These will be called in query(), using a simplified version of the SQL that also
 328          *      includes the agent as a SQL comment.
 329          *   - trxProfiler: Optional TransactionProfiler instance.
 330          *   - errorLogger: Optional callback that takes an Exception and logs it.
 331          *   - cliMode: Whether to consider the execution context that of a CLI script.
 332          *   - agent: Optional name used to identify the end-user in query profiling/logging.
 333          *   - srvCache: Optional BagOStuff instance to an APC-style cache.
 334          * @return Database|null If the database driver or extension cannot be found
 335          * @throws InvalidArgumentException If the database driver or extension cannot be found
 336          * @since 1.18
 337          */
 338         final public static function factory( $dbType, $p = [] ) {
 339                 // For database types with built-in support, the below maps type to IDatabase
 340                 // implementations. For types with multipe driver implementations (PHP extensions),
 341                 // an array can be used, keyed by extension name. In case of an array, the
 342                 // optional 'driver' parameter can be used to force a specific driver. Otherwise,
 343                 // we auto-detect the first available driver. For types without built-in support,
 344                 // an class named "Database<Type>" us used, eg. DatabaseFoo for type 'foo'.
 345                 static $builtinTypes = [
 346                         'mssql' => DatabaseMssql::class,
 347                         'mysql' => [ 'mysqli' => DatabaseMysqli::class ],
 348                         'sqlite' => DatabaseSqlite::class,
 349                         'postgres' => DatabasePostgres::class,
 350                 ];
 351
 352                 $dbType = strtolower( $dbType );
 353                 $class = false;
 354                 if ( isset( $builtinTypes[$dbType] ) ) {
 355                         $possibleDrivers = $builtinTypes[$dbType];
 356                         if ( is_string( $possibleDrivers ) ) {
 357                                 $class = $possibleDrivers;
 358                         } else {
 359                                 if ( !empty( $p['driver'] ) ) {
 360                                         if ( !isset( $possibleDrivers[$p['driver']] ) ) {
 361                                                 throw new InvalidArgumentException( __METHOD__ .
 362                                                         " type '$dbType' does not support driver '{$p['driver']}'" );
 363                                         } else {
 364                                                 $class = $possibleDrivers[$p['driver']];
 365                                         }
 366                                 } else {
 367                                         foreach ( $possibleDrivers as $posDriver => $possibleClass ) {
 368                                                 if ( extension_loaded( $posDriver ) ) {
 369                                                         $class = $possibleClass;
 370                                                         break;
 371                                                 }
 372                                         }
 373                                 }
 374                         }
 375                 } else {
 376                         $class = 'Database' . ucfirst( $dbType );
 377                 }
 378
 379                 if ( $class === false ) {
 380                         throw new InvalidArgumentException( __METHOD__ .
 381                                 " no viable database extension found for type '$dbType'" );
 382                 }
 383
 384                 if ( class_exists( $class ) && is_subclass_of( $class, IDatabase::class ) ) {
 385                         // Resolve some defaults for b/c
 386                         $p['host'] = isset( $p['host'] ) ? $p['host'] : false;
 387                         $p['user'] = isset( $p['user'] ) ? $p['user'] : false;
 388                         $p['password'] = isset( $p['password'] ) ? $p['password'] : false;
 389                         $p['dbname'] = isset( $p['dbname'] ) ? $p['dbname'] : false;
 390                         $p['flags'] = isset( $p['flags'] ) ? $p['flags'] : 0;
 391                         $p['variables'] = isset( $p['variables'] ) ? $p['variables'] : [];
 392                         $p['tablePrefix'] = isset( $p['tablePrefix'] ) ? $p['tablePrefix'] : '';
 393                         $p['schema'] = isset( $p['schema'] ) ? $p['schema'] : '';
 394                         $p['cliMode'] = isset( $p['cliMode'] )
 395                                 ? $p['cliMode']
 396                                 : ( PHP_SAPI === 'cli' || PHP_SAPI === 'phpdbg' );
 397                         $p['agent'] = isset( $p['agent'] ) ? $p['agent'] : '';
 398                         if ( !isset( $p['connLogger'] ) ) {
 399                                 $p['connLogger'] = new \Psr\Log\NullLogger();
 400                         }
 401                         if ( !isset( $p['queryLogger'] ) ) {
 402                                 $p['queryLogger'] = new \Psr\Log\NullLogger();
 403                         }
 404                         $p['profiler'] = isset( $p['profiler'] ) ? $p['profiler'] : null;
 405                         if ( !isset( $p['trxProfiler'] ) ) {
 406                                 $p['trxProfiler'] = new TransactionProfiler();
 407                         }
 408                         if ( !isset( $p['errorLogger'] ) ) {
 409                                 $p['errorLogger'] = function ( Exception $e ) {
 410                                         trigger_error( get_class( $e ) . ': ' . $e->getMessage(), E_USER_WARNING );
 411                                 };
 412                         }
 413
 414                         $conn = new $class( $p );
 415                 } else {
 416                         $conn = null;
 417                 }
 418
 419                 return $conn;
 420         }
 421
 422         /**
 423          * Set the PSR-3 logger interface to use for query logging. (The logger
 424          * interfaces for connection logging and error logging can be set with the
 425          * constructor.)
 426          *
 427          * @param LoggerInterface $logger
 428          */
 429         public function setLogger( LoggerInterface $logger ) {
 430                 $this->queryLogger = $logger;
 431         }
 432
 433         public function getServerInfo() {
 434                 return $this->getServerVersion();
 435         }
 436
 437         public function bufferResults( $buffer = null ) {
 438                 $res = !$this->getFlag( self::DBO_NOBUFFER );
 439                 if ( $buffer !== null ) {
 440                         $buffer
 441                                 ? $this->clearFlag( self::DBO_NOBUFFER )
 442                                 : $this->setFlag( self::DBO_NOBUFFER );
 443                 }
 444
 445                 return $res;
 446         }
 447
 448         /**
 449          * Turns on (false) or off (true) the automatic generation and sending
 450          * of a "we're sorry, but there has been a database error" page on
 451          * database errors. Default is on (false). When turned off, the
 452          * code should use lastErrno() and lastError() to handle the
 453          * situation as appropriate.
 454          *
 455          * Do not use this function outside of the Database classes.
 456          *
 457          * @param null|bool $ignoreErrors
 458          * @return bool The previous value of the flag.
 459          */
 460         protected function ignoreErrors( $ignoreErrors = null ) {
 461                 $res = $this->getFlag( self::DBO_IGNORE );
 462                 if ( $ignoreErrors !== null ) {
 463                         // setFlag()/clearFlag() do not allow DBO_IGNORE changes for sanity
 464                         if ( $ignoreErrors ) {
 465                                 $this->flags |= self::DBO_IGNORE;
 466                         } else {
 467                                 $this->flags &= ~self::DBO_IGNORE;
 468                         }
 469                 }
 470
 471                 return $res;
 472         }
 473
 474         public function trxLevel() {
 475                 return $this->trxLevel;
 476         }
 477
 478         public function trxTimestamp() {
 479                 return $this->trxLevel ? $this->trxTimestamp : null;
 480         }
 481
 482         public function tablePrefix( $prefix = null ) {
 483                 $old = $this->tablePrefix;
 484                 if ( $prefix !== null ) {
 485                         $this->tablePrefix = $prefix;
 486                         $this->currentDomain = ( $this->dbName != '' )
 487                                 ? new DatabaseDomain( $this->dbName, null, $this->tablePrefix )
 488                                 : DatabaseDomain::newUnspecified();
 489                 }
 490
 491                 return $old;
 492         }
 493
 494         public function dbSchema( $schema = null ) {
 495                 $old = $this->schema;
 496                 if ( $schema !== null ) {
 497                         $this->schema = $schema;
 498                 }
 499
 500                 return $old;
 501         }
 502
 503         public function getLBInfo( $name = null ) {
 504                 if ( is_null( $name ) ) {
 505                         return $this->lbInfo;
 506                 } else {
 507                         if ( array_key_exists( $name, $this->lbInfo ) ) {
 508                                 return $this->lbInfo[$name];
 509                         } else {
 510                                 return null;
 511                         }
 512                 }
 513         }
 514
 515         public function setLBInfo( $name, $value = null ) {
 516                 if ( is_null( $value ) ) {
 517                         $this->lbInfo = $name;
 518                 } else {
 519                         $this->lbInfo[$name] = $value;
 520                 }
 521         }
 522
 523         public function setLazyMasterHandle( IDatabase $conn ) {
 524                 $this->lazyMasterHandle = $conn;
 525         }
 526
 527         /**
 528          * @return IDatabase|null
 529          * @see setLazyMasterHandle()
 530          * @since 1.27
 531          */
 532         protected function getLazyMasterHandle() {
 533                 return $this->lazyMasterHandle;
 534         }
 535
 536         public function implicitGroupby() {
 537                 return true;
 538         }
 539
 540         public function implicitOrderby() {
 541                 return true;
 542         }
 543
 544         public function lastQuery() {
 545                 return $this->lastQuery;
 546         }
 547
 548         public function doneWrites() {
 549                 return (bool)$this->lastWriteTime;
 550         }
 551
 552         public function lastDoneWrites() {
 553                 return $this->lastWriteTime ?: false;
 554         }
 555
 556         public function writesPending() {
 557                 return $this->trxLevel && $this->trxDoneWrites;
 558         }
 559
 560         public function writesOrCallbacksPending() {
 561                 return $this->trxLevel && (
 562                         $this->trxDoneWrites || $this->trxIdleCallbacks || $this->trxPreCommitCallbacks
 563                 );
 564         }
 565
 566         public function pendingWriteQueryDuration( $type = self::ESTIMATE_TOTAL ) {
 567                 if ( !$this->trxLevel ) {
 568                         return false;
 569                 } elseif ( !$this->trxDoneWrites ) {
 570                         return 0.0;
 571                 }
 572
 573                 switch ( $type ) {
 574                         case self::ESTIMATE_DB_APPLY:
 575                                 $this->ping( $rtt );
 576                                 $rttAdjTotal = $this->trxWriteAdjQueryCount * $rtt;
 577                                 $applyTime = max( $this->trxWriteAdjDuration - $rttAdjTotal, 0 );
 578                                 // For omitted queries, make them count as something at least
 579                                 $omitted = $this->trxWriteQueryCount - $this->trxWriteAdjQueryCount;
 580                                 $applyTime += self::TINY_WRITE_SEC * $omitted;
 581
 582                                 return $applyTime;
 583                         default: // everything
 584                                 return $this->trxWriteDuration;
 585                 }
 586         }
 587
 588         public function pendingWriteCallers() {
 589                 return $this->trxLevel ? $this->trxWriteCallers : [];
 590         }
 591
 592         public function pendingWriteRowsAffected() {
 593                 return $this->trxWriteAffectedRows;
 594         }
 595
 596         /**
 597          * Get the list of method names that have pending write queries or callbacks
 598          * for this transaction
 599          *
 600          * @return array
 601          */
 602         protected function pendingWriteAndCallbackCallers() {
 603                 if ( !$this->trxLevel ) {
 604                         return [];
 605                 }
 606
 607                 $fnames = $this->trxWriteCallers;
 608                 foreach ( [
 609                         $this->trxIdleCallbacks,
 610                         $this->trxPreCommitCallbacks,
 611                         $this->trxEndCallbacks
 612                 ] as $callbacks ) {
 613                         foreach ( $callbacks as $callback ) {
 614                                 $fnames[] = $callback[1];
 615                         }
 616                 }
 617
 618                 return $fnames;
 619         }
 620
 621         public function isOpen() {
 622                 return $this->opened;
 623         }
 624
 625         public function setFlag( $flag, $remember = self::REMEMBER_NOTHING ) {
 626                 if ( ( $flag & self::DBO_IGNORE ) ) {
 627                         throw new \UnexpectedValueException( "Modifying DBO_IGNORE is not allowed." );
 628                 }
 629
 630                 if ( $remember === self::REMEMBER_PRIOR ) {
 631                         array_push( $this->priorFlags, $this->flags );
 632                 }
 633                 $this->flags |= $flag;
 634         }
 635
 636         public function clearFlag( $flag, $remember = self::REMEMBER_NOTHING ) {
 637                 if ( ( $flag & self::DBO_IGNORE ) ) {
 638                         throw new \UnexpectedValueException( "Modifying DBO_IGNORE is not allowed." );
 639                 }
 640
 641                 if ( $remember === self::REMEMBER_PRIOR ) {
 642                         array_push( $this->priorFlags, $this->flags );
 643                 }
 644                 $this->flags &= ~$flag;
 645         }
 646
 647         public function restoreFlags( $state = self::RESTORE_PRIOR ) {
 648                 if ( !$this->priorFlags ) {
 649                         return;
 650                 }
 651
 652                 if ( $state === self::RESTORE_INITIAL ) {
 653                         $this->flags = reset( $this->priorFlags );
 654                         $this->priorFlags = [];
 655                 } else {
 656                         $this->flags = array_pop( $this->priorFlags );
 657                 }
 658         }
 659
 660         public function getFlag( $flag ) {
 661                 return !!( $this->flags & $flag );
 662         }
 663
 664         /**
 665          * @param string $name Class field name
 666          * @return mixed
 667          * @deprecated Since 1.28
 668          */
 669         public function getProperty( $name ) {
 670                 return $this->$name;
 671         }
 672
 673         public function getDomainID() {
 674                 return $this->currentDomain->getId();
 675         }
 676
 677         final public function getWikiID() {
 678                 return $this->getDomainID();
 679         }
 680
 681         /**
 682          * Get information about an index into an object
 683          * @param string $table Table name
 684          * @param string $index Index name
 685          * @param string $fname Calling function name
 686          * @return mixed Database-specific index description class or false if the index does not exist
 687          */
 688         abstract function indexInfo( $table, $index, $fname = __METHOD__ );
 689
 690         /**
 691          * Wrapper for addslashes()
 692          *
 693          * @param string $s String to be slashed.
 694          * @return string Slashed string.
 695          */
 696         abstract function strencode( $s );
 697
 698         /**
 699          * Set a custom error handler for logging errors during database connection
 700          */
 701         protected function installErrorHandler() {
 702                 $this->phpError = false;
 703                 $this->htmlErrors = ini_set( 'html_errors', '0' );
 704                 set_error_handler( [ $this, 'connectionErrorLogger' ] );
 705         }
 706
 707         /**
 708          * Restore the previous error handler and return the last PHP error for this DB
 709          *
 710          * @return bool|string
 711          */
 712         protected function restoreErrorHandler() {
 713                 restore_error_handler();
 714                 if ( $this->htmlErrors !== false ) {
 715                         ini_set( 'html_errors', $this->htmlErrors );
 716                 }
 717
 718                 return $this->getLastPHPError();
 719         }
 720
 721         /**
 722          * @return string|bool Last PHP error for this DB (typically connection errors)
 723          */
 724         protected function getLastPHPError() {
 725                 if ( $this->phpError ) {
 726                         $error = preg_replace( '!\[<a.*</a>\]!', '', $this->phpError );
 727                         $error = preg_replace( '!^.*?:\s?(.*)$!', '$1', $error );
 728
 729                         return $error;
 730                 }
 731
 732                 return false;
 733         }
 734
 735         /**
 736          * Error handler for logging errors during database connection
 737          * This method should not be used outside of Database classes
 738          *
 739          * @param int $errno
 740          * @param string $errstr
 741          */
 742         public function connectionErrorLogger( $errno, $errstr ) {
 743                 $this->phpError = $errstr;
 744         }
 745
 746         /**
 747          * Create a log context to pass to PSR-3 logger functions.
 748          *
 749          * @param array $extras Additional data to add to context
 750          * @return array
 751          */
 752         protected function getLogContext( array $extras = [] ) {
 753                 return array_merge(
 754                         [
 755                                 'db_server' => $this->server,
 756                                 'db_name' => $this->dbName,
 757                                 'db_user' => $this->user,
 758                         ],
 759                         $extras
 760                 );
 761         }
 762
 763         public function close() {
 764                 if ( $this->conn ) {
 765                         if ( $this->trxLevel() ) {
 766                                 $this->commit( __METHOD__, self::FLUSHING_INTERNAL );
 767                         }
 768
 769                         $closed = $this->closeConnection();
 770                         $this->conn = false;
 771                 } elseif (
 772                         $this->trxIdleCallbacks ||
 773                         $this->trxPreCommitCallbacks ||
 774                         $this->trxEndCallbacks
 775                 ) { // sanity
 776                         throw new RuntimeException( "Transaction callbacks still pending." );
 777                 } else {
 778                         $closed = true;
 779                 }
 780                 $this->opened = false;
 781
 782                 return $closed;
 783         }
 784
 785         /**
 786          * Make sure isOpen() returns true as a sanity check
 787          *
 788          * @throws DBUnexpectedError
 789          */
 790         protected function assertOpen() {
 791                 if ( !$this->isOpen() ) {
 792                         throw new DBUnexpectedError( $this, "DB connection was already closed." );
 793                 }
 794         }
 795
 796         /**
 797          * Closes underlying database connection
 798          * @since 1.20
 799          * @return bool Whether connection was closed successfully
 800          */
 801         abstract protected function closeConnection();
 802
 803         public function reportConnectionError( $error = 'Unknown error' ) {
 804                 $myError = $this->lastError();
 805                 if ( $myError ) {
 806                         $error = $myError;
 807                 }
 808
 809                 # New method
 810                 throw new DBConnectionError( $this, $error );
 811         }
 812
 813         /**
 814          * The DBMS-dependent part of query()
 815          *
 816          * @param string $sql SQL query.
 817          * @return ResultWrapper|bool Result object to feed to fetchObject,
 818          *   fetchRow, ...; or false on failure
 819          */
 820         abstract protected function doQuery( $sql );
 821
 822         /**
 823          * Determine whether a query writes to the DB.
 824          * Should return true if unsure.
 825          *
 826          * @param string $sql
 827          * @return bool
 828          */
 829         protected function isWriteQuery( $sql ) {
 830                 return !preg_match(
 831                         '/^(?:SELECT|BEGIN|ROLLBACK|COMMIT|SET|SHOW|EXPLAIN|\(SELECT)\b/i', $sql );
 832         }
 833
 834         /**
 835          * @param string $sql
 836          * @return string|null
 837          */
 838         protected function getQueryVerb( $sql ) {
 839                 return preg_match( '/^\s*([a-z]+)/i', $sql, $m ) ? strtoupper( $m[1] ) : null;
 840         }
 841
 842         /**
 843          * Determine whether a SQL statement is sensitive to isolation level.
 844          * A SQL statement is considered transactable if its result could vary
 845          * depending on the transaction isolation level. Operational commands
 846          * such as 'SET' and 'SHOW' are not considered to be transactable.
 847          *
 848          * @param string $sql
 849          * @return bool
 850          */
 851         protected function isTransactableQuery( $sql ) {
 852                 return !in_array(
 853                         $this->getQueryVerb( $sql ),
 854                         [ 'BEGIN', 'COMMIT', 'ROLLBACK', 'SHOW', 'SET', 'CREATE', 'ALTER' ],
 855                         true
 856                 );
 857         }
 858
 859         /**
 860          * @param string $sql A SQL query
 861          * @return bool Whether $sql is SQL for TEMPORARY table operation
 862          */
 863         protected function registerTempTableOperation( $sql ) {
 864                 if ( preg_match(
 865                         '/^CREATE\s+TEMPORARY\s+TABLE\s+(?:IF\s+NOT\s+EXISTS\s+)?[`"\']?(\w+)[`"\']?/i',
 866                         $sql,
 867                         $matches
 868                 ) ) {
 869                         $this->sessionTempTables[$matches[1]] = 1;
 870
 871                         return true;
 872                 } elseif ( preg_match(
 873                         '/^DROP\s+(?:TEMPORARY\s+)?TABLE\s+(?:IF\s+EXISTS\s+)?[`"\']?(\w+)[`"\']?/i',
 874                         $sql,
 875                         $matches
 876                 ) ) {
 877                         $isTemp = isset( $this->sessionTempTables[$matches[1]] );
 878                         unset( $this->sessionTempTables[$matches[1]] );
 879
 880                         return $isTemp;
 881                 } elseif ( preg_match(
 882                         '/^TRUNCATE\s+(?:TEMPORARY\s+)?TABLE\s+(?:IF\s+EXISTS\s+)?[`"\']?(\w+)[`"\']?/i',
 883                         $sql,
 884                         $matches
 885                 ) ) {
 886                         return isset( $this->sessionTempTables[$matches[1]] );
 887                 } elseif ( preg_match(
 888                         '/^(?:INSERT\s+(?:\w+\s+)?INTO|UPDATE|DELETE\s+FROM)\s+[`"\']?(\w+)[`"\']?/i',
 889                         $sql,
 890                         $matches
 891                 ) ) {
 892                         return isset( $this->sessionTempTables[$matches[1]] );
 893                 }
 894
 895                 return false;
 896         }
 897
 898         public function query( $sql, $fname = __METHOD__, $tempIgnore = false ) {
 899                 $priorWritesPending = $this->writesOrCallbacksPending();
 900                 $this->lastQuery = $sql;
 901
 902                 $isWrite = $this->isWriteQuery( $sql );
 903                 if ( $isWrite ) {
 904                         $isNonTempWrite = !$this->registerTempTableOperation( $sql );
 905                 } else {
 906                         $isNonTempWrite = false;
 907                 }
 908
 909                 if ( $isWrite ) {
 910                         if ( $this->getLBInfo( 'replica' ) === true ) {
 911                                 throw new DBError(
 912                                         $this,
 913                                         'Write operations are not allowed on replica database connections.'
 914                                 );
 915                         }
 916                         # In theory, non-persistent writes are allowed in read-only mode, but due to things
 917                         # like https://bugs.mysql.com/bug.php?id=33669 that might not work anyway...
 918                         $reason = $this->getReadOnlyReason();
 919                         if ( $reason !== false ) {
 920                                 throw new DBReadOnlyError( $this, "Database is read-only: $reason" );
 921                         }
 922                         # Set a flag indicating that writes have been done
 923                         $this->lastWriteTime = microtime( true );
 924                 }
 925
 926                 # Add trace comment to the begin of the sql string, right after the operator.
 927                 # Or, for one-word queries (like "BEGIN" or COMMIT") add it to the end (T44598)
 928                 $commentedSql = preg_replace( '/\s|$/', " /* $fname {$this->agent} */ ", $sql, 1 );
 929
 930                 # Start implicit transactions that wrap the request if DBO_TRX is enabled
 931                 if ( !$this->trxLevel && $this->getFlag( self::DBO_TRX )
 932                         && $this->isTransactableQuery( $sql )
 933                 ) {
 934                         $this->begin( __METHOD__ . " ($fname)", self::TRANSACTION_INTERNAL );
 935                         $this->trxAutomatic = true;
 936                 }
 937
 938                 # Keep track of whether the transaction has write queries pending
 939                 if ( $this->trxLevel && !$this->trxDoneWrites && $isWrite ) {
 940                         $this->trxDoneWrites = true;
 941                         $this->trxProfiler->transactionWritingIn(
 942                                 $this->server, $this->dbName, $this->trxShortId );
 943                 }
 944
 945                 if ( $this->getFlag( self::DBO_DEBUG ) ) {
 946                         $this->queryLogger->debug( "{$this->dbName} {$commentedSql}" );
 947                 }
 948
 949                 # Avoid fatals if close() was called
 950                 $this->assertOpen();
 951
 952                 # Send the query to the server
 953                 $ret = $this->doProfiledQuery( $sql, $commentedSql, $isNonTempWrite, $fname );
 954
 955                 # Try reconnecting if the connection was lost
 956                 if ( false === $ret && $this->wasErrorReissuable() ) {
 957                         $recoverable = $this->canRecoverFromDisconnect( $sql, $priorWritesPending );
 958                         # Stash the last error values before anything might clear them
 959                         $lastError = $this->lastError();
 960                         $lastErrno = $this->lastErrno();
 961                         # Update state tracking to reflect transaction loss due to disconnection
 962                         $this->handleSessionLoss();
 963                         if ( $this->reconnect() ) {
 964                                 $msg = __METHOD__ . ': lost connection to {dbserver}; reconnected';
 965                                 $params = [ 'dbserver' => $this->getServer() ];
 966                                 $this->connLogger->warning( $msg, $params );
 967                                 $this->queryLogger->warning( $msg, $params +
 968                                         [ 'trace' => ( new RuntimeException() )->getTraceAsString() ] );
 969
 970                                 if ( !$recoverable ) {
 971                                         # Callers may catch the exception and continue to use the DB
 972                                         $this->reportQueryError( $lastError, $lastErrno, $sql, $fname );
 973                                 } else {
 974                                         # Should be safe to silently retry the query
 975                                         $ret = $this->doProfiledQuery( $sql, $commentedSql, $isNonTempWrite, $fname );
 976                                 }
 977                         } else {
 978                                 $msg = __METHOD__ . ': lost connection to {dbserver} permanently';
 979                                 $this->connLogger->error( $msg, [ 'dbserver' => $this->getServer() ] );
 980                         }
 981                 }
 982
 983                 if ( false === $ret ) {
 984                         # Deadlocks cause the entire transaction to abort, not just the statement.
 985                         # https://dev.mysql.com/doc/refman/5.7/en/innodb-error-handling.html
 986                         # https://www.postgresql.org/docs/9.1/static/explicit-locking.html
 987                         if ( $this->wasDeadlock() ) {
 988                                 if ( $this->explicitTrxActive() || $priorWritesPending ) {
 989                                         $tempIgnore = false; // not recoverable
 990                                 }
 991                                 # Update state tracking to reflect transaction loss
 992                                 $this->handleSessionLoss();
 993                         }
 994
 995                         $this->reportQueryError(
 996                                 $this->lastError(), $this->lastErrno(), $sql, $fname, $tempIgnore );
 997                 }
 998
 999                 $res = $this->resultObject( $ret );
1000
1001                 return $res;
1002         }
1003
1004         /**
1005          * Wrapper for query() that also handles profiling, logging, and affected row count updates
1006          *
1007          * @param string $sql Original SQL query
1008          * @param string $commentedSql SQL query with debugging/trace comment
1009          * @param bool $isWrite Whether the query is a (non-temporary) write operation
1010          * @param string $fname Name of the calling function
1011          * @return bool|ResultWrapper True for a successful write query, ResultWrapper
1012          *     object for a successful read query, or false on failure
1013          */
1014         private function doProfiledQuery( $sql, $commentedSql, $isWrite, $fname ) {
1015                 $isMaster = !is_null( $this->getLBInfo( 'master' ) );
1016                 # generalizeSQL() will probably cut down the query to reasonable
1017                 # logging size most of the time. The substr is really just a sanity check.
1018                 if ( $isMaster ) {
1019                         $queryProf = 'query-m: ' . substr( self::generalizeSQL( $sql ), 0, 255 );
1020                 } else {
1021                         $queryProf = 'query: ' . substr( self::generalizeSQL( $sql ), 0, 255 );
1022                 }
1023
1024                 # Include query transaction state
1025                 $queryProf .= $this->trxShortId ? " [TRX#{$this->trxShortId}]" : "";
1026
1027                 $startTime = microtime( true );
1028                 if ( $this->profiler ) {
1029                         call_user_func( [ $this->profiler, 'profileIn' ], $queryProf );
1030                 }
1031                 $this->affectedRowCount = null;
1032                 $ret = $this->doQuery( $commentedSql );
1033                 $this->affectedRowCount = $this->affectedRows();
1034                 if ( $this->profiler ) {
1035                         call_user_func( [ $this->profiler, 'profileOut' ], $queryProf );
1036                 }
1037                 $queryRuntime = max( microtime( true ) - $startTime, 0.0 );
1038
1039                 unset( $queryProfSection ); // profile out (if set)
1040
1041                 if ( $ret !== false ) {
1042                         $this->lastPing = $startTime;
1043                         if ( $isWrite && $this->trxLevel ) {
1044                                 $this->updateTrxWriteQueryTime( $sql, $queryRuntime, $this->affectedRows() );
1045                                 $this->trxWriteCallers[] = $fname;
1046                         }
1047                 }
1048
1049                 if ( $sql === self::PING_QUERY ) {
1050                         $this->rttEstimate = $queryRuntime;
1051                 }
1052
1053                 $this->trxProfiler->recordQueryCompletion(
1054                         $queryProf, $startTime, $isWrite, $this->affectedRows()
1055                 );
1056                 $this->queryLogger->debug( $sql, [
1057                         'method' => $fname,
1058                         'master' => $isMaster,
1059                         'runtime' => $queryRuntime,
1060                 ] );
1061
1062                 return $ret;
1063         }
1064
1065         /**
1066          * Update the estimated run-time of a query, not counting large row lock times
1067          *
1068          * LoadBalancer can be set to rollback transactions that will create huge replication
1069          * lag. It bases this estimate off of pendingWriteQueryDuration(). Certain simple
1070          * queries, like inserting a row can take a long time due to row locking. This method
1071          * uses some simple heuristics to discount those cases.
1072          *
1073          * @param string $sql A SQL write query
1074          * @param float $runtime Total runtime, including RTT
1075          * @param int $affected Affected row count
1076          */
1077         private function updateTrxWriteQueryTime( $sql, $runtime, $affected ) {
1078                 // Whether this is indicative of replica DB runtime (except for RBR or ws_repl)
1079                 $indicativeOfReplicaRuntime = true;
1080                 if ( $runtime > self::SLOW_WRITE_SEC ) {
1081                         $verb = $this->getQueryVerb( $sql );
1082                         // insert(), upsert(), replace() are fast unless bulky in size or blocked on locks
1083                         if ( $verb === 'INSERT' ) {
1084                                 $indicativeOfReplicaRuntime = $this->affectedRows() > self::SMALL_WRITE_ROWS;
1085                         } elseif ( $verb === 'REPLACE' ) {
1086                                 $indicativeOfReplicaRuntime = $this->affectedRows() > self::SMALL_WRITE_ROWS / 2;
1087                         }
1088                 }
1089
1090                 $this->trxWriteDuration += $runtime;
1091                 $this->trxWriteQueryCount += 1;
1092                 $this->trxWriteAffectedRows += $affected;
1093                 if ( $indicativeOfReplicaRuntime ) {
1094                         $this->trxWriteAdjDuration += $runtime;
1095                         $this->trxWriteAdjQueryCount += 1;
1096                 }
1097         }
1098
1099         /**
1100          * Determine whether or not it is safe to retry queries after a database
1101          * connection is lost
1102          *
1103          * @param string $sql SQL query
1104          * @param bool $priorWritesPending Whether there is a transaction open with
1105          *     possible write queries or transaction pre-commit/idle callbacks
1106          *     waiting on it to finish.
1107          * @return bool True if it is safe to retry the query, false otherwise
1108          */
1109         private function canRecoverFromDisconnect( $sql, $priorWritesPending ) {
1110                 # Transaction dropped; this can mean lost writes, or REPEATABLE-READ snapshots.
1111                 # Dropped connections also mean that named locks are automatically released.
1112                 # Only allow error suppression in autocommit mode or when the lost transaction
1113                 # didn't matter anyway (aside from DBO_TRX snapshot loss).
1114                 if ( $this->namedLocksHeld ) {
1115                         return false; // possible critical section violation
1116                 } elseif ( $sql === 'COMMIT' ) {
1117                         return !$priorWritesPending; // nothing written anyway? (T127428)
1118                 } elseif ( $sql === 'ROLLBACK' ) {
1119                         return true; // transaction lost...which is also what was requested :)
1120                 } elseif ( $this->explicitTrxActive() ) {
1121                         return false; // don't drop atomocity
1122                 } elseif ( $priorWritesPending ) {
1123                         return false; // prior writes lost from implicit transaction
1124                 }
1125
1126                 return true;
1127         }
1128
1129         /**
1130          * Clean things up after transaction loss due to disconnection
1131          *
1132          * @return null|Exception
1133          */
1134         private function handleSessionLoss() {
1135                 $this->trxLevel = 0;
1136                 $this->trxIdleCallbacks = []; // T67263
1137                 $this->trxPreCommitCallbacks = []; // T67263
1138                 $this->sessionTempTables = [];
1139                 $this->namedLocksHeld = [];
1140                 try {
1141                         // Handle callbacks in trxEndCallbacks
1142                         $this->runOnTransactionIdleCallbacks( self::TRIGGER_ROLLBACK );
1143                         $this->runTransactionListenerCallbacks( self::TRIGGER_ROLLBACK );
1144                         return null;
1145                 } catch ( Exception $e ) {
1146                         // Already logged; move on...
1147                         return $e;
1148                 }
1149         }
1150
1151         /**
1152          * Checks whether the cause of the error is detected to be a timeout.
1153          *
1154          * It returns false by default, and not all engines support detecting this yet.
1155          * If this returns false, it will be treated as a generic query error.
1156          *
1157          * @param string $error Error text
1158          * @param int $errno Error number
1159          * @return bool
1160          */
1161         protected function wasQueryTimeout( $error, $errno ) {
1162                 return false;
1163         }
1164
1165         public function reportQueryError( $error, $errno, $sql, $fname, $tempIgnore = false ) {
1166                 if ( $this->ignoreErrors() || $tempIgnore ) {
1167                         $this->queryLogger->debug( "SQL ERROR (ignored): $error\n" );
1168                 } else {
1169                         $sql1line = mb_substr( str_replace( "\n", "\\n", $sql ), 0, 5 * 1024 );
1170                         $this->queryLogger->error(
1171                                 "{fname}\t{db_server}\t{errno}\t{error}\t{sql1line}",
1172                                 $this->getLogContext( [
1173                                         'method' => __METHOD__,
1174                                         'errno' => $errno,
1175                                         'error' => $error,
1176                                         'sql1line' => $sql1line,
1177                                         'fname' => $fname,
1178                                 ] )
1179                         );
1180                         $this->queryLogger->debug( "SQL ERROR: " . $error . "\n" );
1181                         $wasQueryTimeout = $this->wasQueryTimeout( $error, $errno );
1182                         if ( $wasQueryTimeout ) {
1183                                 throw new DBQueryTimeoutError( $this, $error, $errno, $sql, $fname );
1184                         } else {
1185                                 throw new DBQueryError( $this, $error, $errno, $sql, $fname );
1186                         }
1187                 }
1188         }
1189
1190         public function freeResult( $res ) {
1191         }
1192
1193         public function selectField(
1194                 $table, $var, $cond = '', $fname = __METHOD__, $options = [], $join_conds = []
1195         ) {
1196                 if ( $var === '*' ) { // sanity
1197                         throw new DBUnexpectedError( $this, "Cannot use a * field: got '$var'" );
1198                 }
1199
1200                 if ( !is_array( $options ) ) {
1201                         $options = [ $options ];
1202                 }
1203
1204                 $options['LIMIT'] = 1;
1205
1206                 $res = $this->select( $table, $var, $cond, $fname, $options, $join_conds );
1207                 if ( $res === false || !$this->numRows( $res ) ) {
1208                         return false;
1209                 }
1210
1211                 $row = $this->fetchRow( $res );
1212
1213                 if ( $row !== false ) {
1214                         return reset( $row );
1215                 } else {
1216                         return false;
1217                 }
1218         }
1219
1220         public function selectFieldValues(
1221                 $table, $var, $cond = '', $fname = __METHOD__, $options = [], $join_conds = []
1222         ) {
1223                 if ( $var === '*' ) { // sanity
1224                         throw new DBUnexpectedError( $this, "Cannot use a * field" );
1225                 } elseif ( !is_string( $var ) ) { // sanity
1226                         throw new DBUnexpectedError( $this, "Cannot use an array of fields" );
1227                 }
1228
1229                 if ( !is_array( $options ) ) {
1230                         $options = [ $options ];
1231                 }
1232
1233                 $res = $this->select( $table, $var, $cond, $fname, $options, $join_conds );
1234                 if ( $res === false ) {
1235                         return false;
1236                 }
1237
1238                 $values = [];
1239                 foreach ( $res as $row ) {
1240                         $values[] = $row->$var;
1241                 }
1242
1243                 return $values;
1244         }
1245
1246         /**
1247          * Returns an optional USE INDEX clause to go after the table, and a
1248          * string to go at the end of the query.
1249          *
1250          * @param array $options Associative array of options to be turned into
1251          *   an SQL query, valid keys are listed in the function.
1252          * @return array
1253          * @see Database::select()
1254          */
1255         protected function makeSelectOptions( $options ) {
1256                 $preLimitTail = $postLimitTail = '';
1257                 $startOpts = '';
1258
1259                 $noKeyOptions = [];
1260
1261                 foreach ( $options as $key => $option ) {
1262                         if ( is_numeric( $key ) ) {
1263                                 $noKeyOptions[$option] = true;
1264                         }
1265                 }
1266
1267                 $preLimitTail .= $this->makeGroupByWithHaving( $options );
1268
1269                 $preLimitTail .= $this->makeOrderBy( $options );
1270
1271                 if ( isset( $noKeyOptions['FOR UPDATE'] ) ) {
1272                         $postLimitTail .= ' FOR UPDATE';
1273                 }
1274
1275                 if ( isset( $noKeyOptions['LOCK IN SHARE MODE'] ) ) {
1276                         $postLimitTail .= ' LOCK IN SHARE MODE';
1277                 }
1278
1279                 if ( isset( $noKeyOptions['DISTINCT'] ) || isset( $noKeyOptions['DISTINCTROW'] ) ) {
1280                         $startOpts .= 'DISTINCT';
1281                 }
1282
1283                 # Various MySQL extensions
1284                 if ( isset( $noKeyOptions['STRAIGHT_JOIN'] ) ) {
1285                         $startOpts .= ' /*! STRAIGHT_JOIN */';
1286                 }
1287
1288                 if ( isset( $noKeyOptions['HIGH_PRIORITY'] ) ) {
1289                         $startOpts .= ' HIGH_PRIORITY';
1290                 }
1291
1292                 if ( isset( $noKeyOptions['SQL_BIG_RESULT'] ) ) {
1293                         $startOpts .= ' SQL_BIG_RESULT';
1294                 }
1295
1296                 if ( isset( $noKeyOptions['SQL_BUFFER_RESULT'] ) ) {
1297                         $startOpts .= ' SQL_BUFFER_RESULT';
1298                 }
1299
1300                 if ( isset( $noKeyOptions['SQL_SMALL_RESULT'] ) ) {
1301                         $startOpts .= ' SQL_SMALL_RESULT';
1302                 }
1303
1304                 if ( isset( $noKeyOptions['SQL_CALC_FOUND_ROWS'] ) ) {
1305                         $startOpts .= ' SQL_CALC_FOUND_ROWS';
1306                 }
1307
1308                 if ( isset( $noKeyOptions['SQL_CACHE'] ) ) {
1309                         $startOpts .= ' SQL_CACHE';
1310                 }
1311
1312                 if ( isset( $noKeyOptions['SQL_NO_CACHE'] ) ) {
1313                         $startOpts .= ' SQL_NO_CACHE';
1314                 }
1315
1316                 if ( isset( $options['USE INDEX'] ) && is_string( $options['USE INDEX'] ) ) {
1317                         $useIndex = $this->useIndexClause( $options['USE INDEX'] );
1318                 } else {
1319                         $useIndex = '';
1320                 }
1321                 if ( isset( $options['IGNORE INDEX'] ) && is_string( $options['IGNORE INDEX'] ) ) {
1322                         $ignoreIndex = $this->ignoreIndexClause( $options['IGNORE INDEX'] );
1323                 } else {
1324                         $ignoreIndex = '';
1325                 }
1326
1327                 return [ $startOpts, $useIndex, $preLimitTail, $postLimitTail, $ignoreIndex ];
1328         }
1329
1330         /**
1331          * Returns an optional GROUP BY with an optional HAVING
1332          *
1333          * @param array $options Associative array of options
1334          * @return string
1335          * @see Database::select()
1336          * @since 1.21
1337          */
1338         protected function makeGroupByWithHaving( $options ) {
1339                 $sql = '';
1340                 if ( isset( $options['GROUP BY'] ) ) {
1341                         $gb = is_array( $options['GROUP BY'] )
1342                                 ? implode( ',', $options['GROUP BY'] )
1343                                 : $options['GROUP BY'];
1344                         $sql .= ' GROUP BY ' . $gb;
1345                 }
1346                 if ( isset( $options['HAVING'] ) ) {
1347                         $having = is_array( $options['HAVING'] )
1348                                 ? $this->makeList( $options['HAVING'], self::LIST_AND )
1349                                 : $options['HAVING'];
1350                         $sql .= ' HAVING ' . $having;
1351                 }
1352
1353                 return $sql;
1354         }
1355
1356         /**
1357          * Returns an optional ORDER BY
1358          *
1359          * @param array $options Associative array of options
1360          * @return string
1361          * @see Database::select()
1362          * @since 1.21
1363          */
1364         protected function makeOrderBy( $options ) {
1365                 if ( isset( $options['ORDER BY'] ) ) {
1366                         $ob = is_array( $options['ORDER BY'] )
1367                                 ? implode( ',', $options['ORDER BY'] )
1368                                 : $options['ORDER BY'];
1369
1370                         return ' ORDER BY ' . $ob;
1371                 }
1372
1373                 return '';
1374         }
1375
1376         public function select( $table, $vars, $conds = '', $fname = __METHOD__,
1377                 $options = [], $join_conds = [] ) {
1378                 $sql = $this->selectSQLText( $table, $vars, $conds, $fname, $options, $join_conds );
1379
1380                 return $this->query( $sql, $fname );
1381         }
1382
1383         public function selectSQLText( $table, $vars, $conds = '', $fname = __METHOD__,
1384                 $options = [], $join_conds = []
1385         ) {
1386                 if ( is_array( $vars ) ) {
1387                         $vars = implode( ',', $this->fieldNamesWithAlias( $vars ) );
1388                 }
1389
1390                 $options = (array)$options;
1391                 $useIndexes = ( isset( $options['USE INDEX'] ) && is_array( $options['USE INDEX'] ) )
1392                         ? $options['USE INDEX']
1393                         : [];
1394                 $ignoreIndexes = (
1395                         isset( $options['IGNORE INDEX'] ) &&
1396                         is_array( $options['IGNORE INDEX'] )
1397                 )
1398                         ? $options['IGNORE INDEX']
1399                         : [];
1400
1401                 if ( is_array( $table ) ) {
1402                         $from = ' FROM ' .
1403                                 $this->tableNamesWithIndexClauseOrJOIN(
1404                                         $table, $useIndexes, $ignoreIndexes, $join_conds );
1405                 } elseif ( $table != '' ) {
1406                         $from = ' FROM ' .
1407                                 $this->tableNamesWithIndexClauseOrJOIN(
1408                                         [ $table ], $useIndexes, $ignoreIndexes, [] );
1409                 } else {
1410                         $from = '';
1411                 }
1412
1413                 list( $startOpts, $useIndex, $preLimitTail, $postLimitTail, $ignoreIndex ) =
1414                         $this->makeSelectOptions( $options );
1415
1416                 if ( !empty( $conds ) ) {
1417                         if ( is_array( $conds ) ) {
1418                                 $conds = $this->makeList( $conds, self::LIST_AND );
1419                         }
1420                         $sql = "SELECT $startOpts $vars $from $useIndex $ignoreIndex " .
1421                                 "WHERE $conds $preLimitTail";
1422                 } else {
1423                         $sql = "SELECT $startOpts $vars $from $useIndex $ignoreIndex $preLimitTail";
1424                 }
1425
1426                 if ( isset( $options['LIMIT'] ) ) {
1427                         $sql = $this->limitResult( $sql, $options['LIMIT'],
1428                                 isset( $options['OFFSET'] ) ? $options['OFFSET'] : false );
1429                 }
1430                 $sql = "$sql $postLimitTail";
1431
1432                 if ( isset( $options['EXPLAIN'] ) ) {
1433                         $sql = 'EXPLAIN ' . $sql;
1434                 }
1435
1436                 return $sql;
1437         }
1438
1439         public function selectRow( $table, $vars, $conds, $fname = __METHOD__,
1440                 $options = [], $join_conds = []
1441         ) {
1442                 $options = (array)$options;
1443                 $options['LIMIT'] = 1;
1444                 $res = $this->select( $table, $vars, $conds, $fname, $options, $join_conds );
1445
1446                 if ( $res === false ) {
1447                         return false;
1448                 }
1449
1450                 if ( !$this->numRows( $res ) ) {
1451                         return false;
1452                 }
1453
1454                 $obj = $this->fetchObject( $res );
1455
1456                 return $obj;
1457         }
1458
1459         public function estimateRowCount(
1460                 $table, $vars = '*', $conds = '', $fname = __METHOD__, $options = []
1461         ) {
1462                 $rows = 0;
1463                 $res = $this->select( $table, [ 'rowcount' => 'COUNT(*)' ], $conds, $fname, $options );
1464
1465                 if ( $res ) {
1466                         $row = $this->fetchRow( $res );
1467                         $rows = ( isset( $row['rowcount'] ) ) ? (int)$row['rowcount'] : 0;
1468                 }
1469
1470                 return $rows;
1471         }
1472
1473         public function selectRowCount(
1474                 $tables, $vars = '*', $conds = '', $fname = __METHOD__, $options = [], $join_conds = []
1475         ) {
1476                 $rows = 0;
1477                 $sql = $this->selectSQLText( $tables, '1', $conds, $fname, $options, $join_conds );
1478                 // The identifier quotes is primarily for MSSQL.
1479                 $rowCountCol = $this->addIdentifierQuotes( "rowcount" );
1480                 $tableName = $this->addIdentifierQuotes( "tmp_count" );
1481                 $res = $this->query( "SELECT COUNT(*) AS $rowCountCol FROM ($sql) $tableName", $fname );
1482
1483                 if ( $res ) {
1484                         $row = $this->fetchRow( $res );
1485                         $rows = ( isset( $row['rowcount'] ) ) ? (int)$row['rowcount'] : 0;
1486                 }
1487
1488                 return $rows;
1489         }
1490
1491         /**
1492          * Removes most variables from an SQL query and replaces them with X or N for numbers.
1493          * It's only slightly flawed. Don't use for anything important.
1494          *
1495          * @param string $sql A SQL Query
1496          *
1497          * @return string
1498          */
1499         protected static function generalizeSQL( $sql ) {
1500                 # This does the same as the regexp below would do, but in such a way
1501                 # as to avoid crashing php on some large strings.
1502                 # $sql = preg_replace( "/'([^\\\\']|\\\\.)*'|\"([^\\\\\"]|\\\\.)*\"/", "'X'", $sql );
1503
1504                 $sql = str_replace( "\\\\", '', $sql );
1505                 $sql = str_replace( "\\'", '', $sql );
1506                 $sql = str_replace( "\\\"", '', $sql );
1507                 $sql = preg_replace( "/'.*'/s", "'X'", $sql );
1508                 $sql = preg_replace( '/".*"/s', "'X'", $sql );
1509
1510                 # All newlines, tabs, etc replaced by single space
1511                 $sql = preg_replace( '/\s+/', ' ', $sql );
1512
1513                 # All numbers => N,
1514                 # except the ones surrounded by characters, e.g. l10n
1515                 $sql = preg_replace( '/-?\d+(,-?\d+)+/s', 'N,...,N', $sql );
1516                 $sql = preg_replace( '/(?<![a-zA-Z])-?\d+(?![a-zA-Z])/s', 'N', $sql );
1517
1518                 return $sql;
1519         }
1520
1521         public function fieldExists( $table, $field, $fname = __METHOD__ ) {
1522                 $info = $this->fieldInfo( $table, $field );
1523
1524                 return (bool)$info;
1525         }
1526
1527         public function indexExists( $table, $index, $fname = __METHOD__ ) {
1528                 if ( !$this->tableExists( $table ) ) {
1529                         return null;
1530                 }
1531
1532                 $info = $this->indexInfo( $table, $index, $fname );
1533                 if ( is_null( $info ) ) {
1534                         return null;
1535                 } else {
1536                         return $info !== false;
1537                 }
1538         }
1539
1540         public function tableExists( $table, $fname = __METHOD__ ) {
1541                 $tableRaw = $this->tableName( $table, 'raw' );
1542                 if ( isset( $this->sessionTempTables[$tableRaw] ) ) {
1543                         return true; // already known to exist
1544                 }
1545
1546                 $table = $this->tableName( $table );
1547                 $ignoreErrors = true;
1548                 $res = $this->query( "SELECT 1 FROM $table LIMIT 1", $fname, $ignoreErrors );
1549
1550                 return (bool)$res;
1551         }
1552
1553         public function indexUnique( $table, $index ) {
1554                 $indexInfo = $this->indexInfo( $table, $index );
1555
1556                 if ( !$indexInfo ) {
1557                         return null;
1558                 }
1559
1560                 return !$indexInfo[0]->Non_unique;
1561         }
1562
1563         /**
1564          * Helper for Database::insert().
1565          *
1566          * @param array $options
1567          * @return string
1568          */
1569         protected function makeInsertOptions( $options ) {
1570                 return implode( ' ', $options );
1571         }
1572
1573         public function insert( $table, $a, $fname = __METHOD__, $options = [] ) {
1574                 # No rows to insert, easy just return now
1575                 if ( !count( $a ) ) {
1576                         return true;
1577                 }
1578
1579                 $table = $this->tableName( $table );
1580
1581                 if ( !is_array( $options ) ) {
1582                         $options = [ $options ];
1583                 }
1584
1585                 $fh = null;
1586                 if ( isset( $options['fileHandle'] ) ) {
1587                         $fh = $options['fileHandle'];
1588                 }
1589                 $options = $this->makeInsertOptions( $options );
1590
1591                 if ( isset( $a[0] ) && is_array( $a[0] ) ) {
1592                         $multi = true;
1593                         $keys = array_keys( $a[0] );
1594                 } else {
1595                         $multi = false;
1596                         $keys = array_keys( $a );
1597                 }
1598
1599                 $sql = 'INSERT ' . $options .
1600                         " INTO $table (" . implode( ',', $keys ) . ') VALUES ';
1601
1602                 if ( $multi ) {
1603                         $first = true;
1604                         foreach ( $a as $row ) {
1605                                 if ( $first ) {
1606                                         $first = false;
1607                                 } else {
1608                                         $sql .= ',';
1609                                 }
1610                                 $sql .= '(' . $this->makeList( $row ) . ')';
1611                         }
1612                 } else {
1613                         $sql .= '(' . $this->makeList( $a ) . ')';
1614                 }
1615
1616                 if ( $fh !== null && false === fwrite( $fh, $sql ) ) {
1617                         return false;
1618                 } elseif ( $fh !== null ) {
1619                         return true;
1620                 }
1621
1622                 return (bool)$this->query( $sql, $fname );
1623         }
1624
1625         /**
1626          * Make UPDATE options array for Database::makeUpdateOptions
1627          *
1628          * @param array $options
1629          * @return array
1630          */
1631         protected function makeUpdateOptionsArray( $options ) {
1632                 if ( !is_array( $options ) ) {
1633                         $options = [ $options ];
1634                 }
1635
1636                 $opts = [];
1637
1638                 if ( in_array( 'IGNORE', $options ) ) {
1639                         $opts[] = 'IGNORE';
1640                 }
1641
1642                 return $opts;
1643         }
1644
1645         /**
1646          * Make UPDATE options for the Database::update function
1647          *
1648          * @param array $options The options passed to Database::update
1649          * @return string
1650          */
1651         protected function makeUpdateOptions( $options ) {
1652                 $opts = $this->makeUpdateOptionsArray( $options );
1653
1654                 return implode( ' ', $opts );
1655         }
1656
1657         public function update( $table, $values, $conds, $fname = __METHOD__, $options = [] ) {
1658                 $table = $this->tableName( $table );
1659                 $opts = $this->makeUpdateOptions( $options );
1660                 $sql = "UPDATE $opts $table SET " . $this->makeList( $values, self::LIST_SET );
1661
1662                 if ( $conds !== [] && $conds !== '*' ) {
1663                         $sql .= " WHERE " . $this->makeList( $conds, self::LIST_AND );
1664                 }
1665
1666                 return (bool)$this->query( $sql, $fname );
1667         }
1668
1669         public function makeList( $a, $mode = self::LIST_COMMA ) {
1670                 if ( !is_array( $a ) ) {
1671                         throw new DBUnexpectedError( $this, __METHOD__ . ' called with incorrect parameters' );
1672                 }
1673
1674                 $first = true;
1675                 $list = '';
1676
1677                 foreach ( $a as $field => $value ) {
1678                         if ( !$first ) {
1679                                 if ( $mode == self::LIST_AND ) {
1680                                         $list .= ' AND ';
1681                                 } elseif ( $mode == self::LIST_OR ) {
1682                                         $list .= ' OR ';
1683                                 } else {
1684                                         $list .= ',';
1685                                 }
1686                         } else {
1687                                 $first = false;
1688                         }
1689
1690                         if ( ( $mode == self::LIST_AND || $mode == self::LIST_OR ) && is_numeric( $field ) ) {
1691                                 $list .= "($value)";
1692                         } elseif ( $mode == self::LIST_SET && is_numeric( $field ) ) {
1693                                 $list .= "$value";
1694                         } elseif (
1695                                 ( $mode == self::LIST_AND || $mode == self::LIST_OR ) && is_array( $value )
1696                         ) {
1697                                 // Remove null from array to be handled separately if found
1698                                 $includeNull = false;
1699                                 foreach ( array_keys( $value, null, true ) as $nullKey ) {
1700                                         $includeNull = true;
1701                                         unset( $value[$nullKey] );
1702                                 }
1703                                 if ( count( $value ) == 0 && !$includeNull ) {
1704                                         throw new InvalidArgumentException(
1705                                                 __METHOD__ . ": empty input for field $field" );
1706                                 } elseif ( count( $value ) == 0 ) {
1707                                         // only check if $field is null
1708                                         $list .= "$field IS NULL";
1709                                 } else {
1710                                         // IN clause contains at least one valid element
1711                                         if ( $includeNull ) {
1712                                                 // Group subconditions to ensure correct precedence
1713                                                 $list .= '(';
1714                                         }
1715                                         if ( count( $value ) == 1 ) {
1716                                                 // Special-case single values, as IN isn't terribly efficient
1717                                                 // Don't necessarily assume the single key is 0; we don't
1718                                                 // enforce linear numeric ordering on other arrays here.
1719                                                 $value = array_values( $value )[0];
1720                                                 $list .= $field . " = " . $this->addQuotes( $value );
1721                                         } else {
1722                                                 $list .= $field . " IN (" . $this->makeList( $value ) . ") ";
1723                                         }
1724                                         // if null present in array, append IS NULL
1725                                         if ( $includeNull ) {
1726                                                 $list .= " OR $field IS NULL)";
1727                                         }
1728                                 }
1729                         } elseif ( $value === null ) {
1730                                 if ( $mode == self::LIST_AND || $mode == self::LIST_OR ) {
1731                                         $list .= "$field IS ";
1732                                 } elseif ( $mode == self::LIST_SET ) {
1733                                         $list .= "$field = ";
1734                                 }
1735                                 $list .= 'NULL';
1736                         } else {
1737                                 if (
1738                                         $mode == self::LIST_AND || $mode == self::LIST_OR || $mode == self::LIST_SET
1739                                 ) {
1740                                         $list .= "$field = ";
1741                                 }
1742                                 $list .= $mode == self::LIST_NAMES ? $value : $this->addQuotes( $value );
1743                         }
1744                 }
1745
1746                 return $list;
1747         }
1748
1749         public function makeWhereFrom2d( $data, $baseKey, $subKey ) {
1750                 $conds = [];
1751
1752                 foreach ( $data as $base => $sub ) {
1753                         if ( count( $sub ) ) {
1754                                 $conds[] = $this->makeList(
1755                                         [ $baseKey => $base, $subKey => array_keys( $sub ) ],
1756                                         self::LIST_AND );
1757                         }
1758                 }
1759
1760                 if ( $conds ) {
1761                         return $this->makeList( $conds, self::LIST_OR );
1762                 } else {
1763                         // Nothing to search for...
1764                         return false;
1765                 }
1766         }
1767
1768         public function aggregateValue( $valuedata, $valuename = 'value' ) {
1769                 return $valuename;
1770         }
1771
1772         public function bitNot( $field ) {
1773                 return "(~$field)";
1774         }
1775
1776         public function bitAnd( $fieldLeft, $fieldRight ) {
1777                 return "($fieldLeft & $fieldRight)";
1778         }
1779
1780         public function bitOr( $fieldLeft, $fieldRight ) {
1781                 return "($fieldLeft | $fieldRight)";
1782         }
1783
1784         public function buildConcat( $stringList ) {
1785                 return 'CONCAT(' . implode( ',', $stringList ) . ')';
1786         }
1787
1788         public function buildGroupConcatField(
1789                 $delim, $table, $field, $conds = '', $join_conds = []
1790         ) {
1791                 $fld = "GROUP_CONCAT($field SEPARATOR " . $this->addQuotes( $delim ) . ')';
1792
1793                 return '(' . $this->selectSQLText( $table, $fld, $conds, null, [], $join_conds ) . ')';
1794         }
1795
1796         public function buildStringCast( $field ) {
1797                 return $field;
1798         }
1799
1800         public function databasesAreIndependent() {
1801                 return false;
1802         }
1803
1804         public function selectDB( $db ) {
1805                 # Stub. Shouldn't cause serious problems if it's not overridden, but
1806                 # if your database engine supports a concept similar to MySQL's
1807                 # databases you may as well.
1808                 $this->dbName = $db;
1809
1810                 return true;
1811         }
1812
1813         public function getDBname() {
1814                 return $this->dbName;
1815         }
1816
1817         public function getServer() {
1818                 return $this->server;
1819         }
1820
1821         public function tableName( $name, $format = 'quoted' ) {
1822                 # Skip the entire process when we have a string quoted on both ends.
1823                 # Note that we check the end so that we will still quote any use of
1824                 # use of `database`.table. But won't break things if someone wants
1825                 # to query a database table with a dot in the name.
1826                 if ( $this->isQuotedIdentifier( $name ) ) {
1827                         return $name;
1828                 }
1829
1830                 # Lets test for any bits of text that should never show up in a table
1831                 # name. Basically anything like JOIN or ON which are actually part of
1832                 # SQL queries, but may end up inside of the table value to combine
1833                 # sql. Such as how the API is doing.
1834                 # Note that we use a whitespace test rather than a \b test to avoid
1835                 # any remote case where a word like on may be inside of a table name
1836                 # surrounded by symbols which may be considered word breaks.
1837                 if ( preg_match( '/(^|\s)(DISTINCT|JOIN|ON|AS)(\s|$)/i', $name ) !== 0 ) {
1838                         return $name;
1839                 }
1840
1841                 # Split database and table into proper variables.
1842                 list( $database, $schema, $prefix, $table ) = $this->qualifiedTableComponents( $name );
1843
1844                 # Quote $table and apply the prefix if not quoted.
1845                 # $tableName might be empty if this is called from Database::replaceVars()
1846                 $tableName = "{$prefix}{$table}";
1847                 if ( $format === 'quoted'
1848                         && !$this->isQuotedIdentifier( $tableName )
1849                         && $tableName !== ''
1850                 ) {
1851                         $tableName = $this->addIdentifierQuotes( $tableName );
1852                 }
1853
1854                 # Quote $schema and $database and merge them with the table name if needed
1855                 $tableName = $this->prependDatabaseOrSchema( $schema, $tableName, $format );
1856                 $tableName = $this->prependDatabaseOrSchema( $database, $tableName, $format );
1857
1858                 return $tableName;
1859         }
1860
1861         /**
1862          * Get the table components needed for a query given the currently selected database
1863          *
1864          * @param string $name Table name in the form of db.schema.table, db.table, or table
1865          * @return array (DB name or "" for default, schema name, table prefix, table name)
1866          */
1867         protected function qualifiedTableComponents( $name ) {
1868                 # We reverse the explode so that database.table and table both output the correct table.
1869                 $dbDetails = explode( '.', $name, 3 );
1870                 if ( count( $dbDetails ) == 3 ) {
1871                         list( $database, $schema, $table ) = $dbDetails;
1872                         # We don't want any prefix added in this case
1873                         $prefix = '';
1874                 } elseif ( count( $dbDetails ) == 2 ) {
1875                         list( $database, $table ) = $dbDetails;
1876                         # We don't want any prefix added in this case
1877                         $prefix = '';
1878                         # In dbs that support it, $database may actually be the schema
1879                         # but that doesn't affect any of the functionality here
1880                         $schema = '';
1881                 } else {
1882                         list( $table ) = $dbDetails;
1883                         if ( isset( $this->tableAliases[$table] ) ) {
1884                                 $database = $this->tableAliases[$table]['dbname'];
1885                                 $schema = is_string( $this->tableAliases[$table]['schema'] )
1886                                         ? $this->tableAliases[$table]['schema']
1887                                         : $this->schema;
1888                                 $prefix = is_string( $this->tableAliases[$table]['prefix'] )
1889                                         ? $this->tableAliases[$table]['prefix']
1890                                         : $this->tablePrefix;
1891                         } else {
1892                                 $database = '';
1893                                 $schema = $this->schema; # Default schema
1894                                 $prefix = $this->tablePrefix; # Default prefix
1895                         }
1896                 }
1897
1898                 return [ $database, $schema, $prefix, $table ];
1899         }
1900
1901         /**
1902          * @param string|null $namespace Database or schema
1903          * @param string $relation Name of table, view, sequence, etc...
1904          * @param string $format One of (raw, quoted)
1905          * @return string Relation name with quoted and merged $namespace as needed
1906          */
1907         private function prependDatabaseOrSchema( $namespace, $relation, $format ) {
1908                 if ( strlen( $namespace ) ) {
1909                         if ( $format === 'quoted' && !$this->isQuotedIdentifier( $namespace ) ) {
1910                                 $namespace = $this->addIdentifierQuotes( $namespace );
1911                         }
1912                         $relation = $namespace . '.' . $relation;
1913                 }
1914
1915                 return $relation;
1916         }
1917
1918         public function tableNames() {
1919                 $inArray = func_get_args();
1920                 $retVal = [];
1921
1922                 foreach ( $inArray as $name ) {
1923                         $retVal[$name] = $this->tableName( $name );
1924                 }
1925
1926                 return $retVal;
1927         }
1928
1929         public function tableNamesN() {
1930                 $inArray = func_get_args();
1931                 $retVal = [];
1932
1933                 foreach ( $inArray as $name ) {
1934                         $retVal[] = $this->tableName( $name );
1935                 }
1936
1937                 return $retVal;
1938         }
1939
1940         /**
1941          * Get an aliased table name
1942          * e.g. tableName AS newTableName
1943          *
1944          * @param string $name Table name, see tableName()
1945          * @param string|bool $alias Alias (optional)
1946          * @return string SQL name for aliased table. Will not alias a table to its own name
1947          */
1948         protected function tableNameWithAlias( $name, $alias = false ) {
1949                 if ( !$alias || $alias == $name ) {
1950                         return $this->tableName( $name );
1951                 } else {
1952                         return $this->tableName( $name ) . ' ' . $this->addIdentifierQuotes( $alias );
1953                 }
1954         }
1955
1956         /**
1957          * Gets an array of aliased table names
1958          *
1959          * @param array $tables [ [alias] => table ]
1960          * @return string[] See tableNameWithAlias()
1961          */
1962         protected function tableNamesWithAlias( $tables ) {
1963                 $retval = [];
1964                 foreach ( $tables as $alias => $table ) {
1965                         if ( is_numeric( $alias ) ) {
1966                                 $alias = $table;
1967                         }
1968                         $retval[] = $this->tableNameWithAlias( $table, $alias );
1969                 }
1970
1971                 return $retval;
1972         }
1973
1974         /**
1975          * Get an aliased field name
1976          * e.g. fieldName AS newFieldName
1977          *
1978          * @param string $name Field name
1979          * @param string|bool $alias Alias (optional)
1980          * @return string SQL name for aliased field. Will not alias a field to its own name
1981          */
1982         protected function fieldNameWithAlias( $name, $alias = false ) {
1983                 if ( !$alias || (string)$alias === (string)$name ) {
1984                         return $name;
1985                 } else {
1986                         return $name . ' AS ' . $this->addIdentifierQuotes( $alias ); // PostgreSQL needs AS
1987                 }
1988         }
1989
1990         /**
1991          * Gets an array of aliased field names
1992          *
1993          * @param array $fields [ [alias] => field ]
1994          * @return string[] See fieldNameWithAlias()
1995          */
1996         protected function fieldNamesWithAlias( $fields ) {
1997                 $retval = [];
1998                 foreach ( $fields as $alias => $field ) {
1999                         if ( is_numeric( $alias ) ) {
2000                                 $alias = $field;
2001                         }
2002                         $retval[] = $this->fieldNameWithAlias( $field, $alias );
2003                 }
2004
2005                 return $retval;
2006         }
2007
2008         /**
2009          * Get the aliased table name clause for a FROM clause
2010          * which might have a JOIN and/or USE INDEX or IGNORE INDEX clause
2011          *
2012          * @param array $tables ( [alias] => table )
2013          * @param array $use_index Same as for select()
2014          * @param array $ignore_index Same as for select()
2015          * @param array $join_conds Same as for select()
2016          * @return string
2017          */
2018         protected function tableNamesWithIndexClauseOrJOIN(
2019                 $tables, $use_index = [], $ignore_index = [], $join_conds = []
2020         ) {
2021                 $ret = [];
2022                 $retJOIN = [];
2023                 $use_index = (array)$use_index;
2024                 $ignore_index = (array)$ignore_index;
2025                 $join_conds = (array)$join_conds;
2026
2027                 foreach ( $tables as $alias => $table ) {
2028                         if ( !is_string( $alias ) ) {
2029                                 // No alias? Set it equal to the table name
2030                                 $alias = $table;
2031                         }
2032
2033                         if ( is_array( $table ) ) {
2034                                 // A parenthesized group
2035                                 if ( count( $table ) > 1 ) {
2036                                         $joinedTable = '('
2037                                                 . $this->tableNamesWithIndexClauseOrJOIN( $table, $use_index, $ignore_index, $join_conds )
2038                                                 . ')';
2039                                 } else {
2040                                         // Degenerate case
2041                                         $innerTable = reset( $table );
2042                                         $innerAlias = key( $table );
2043                                         $joinedTable = $this->tableNameWithAlias(
2044                                                 $innerTable,
2045                                                 is_string( $innerAlias ) ? $innerAlias : $innerTable
2046                                         );
2047                                 }
2048                         } else {
2049                                 $joinedTable = $this->tableNameWithAlias( $table, $alias );
2050                         }
2051
2052                         // Is there a JOIN clause for this table?
2053                         if ( isset( $join_conds[$alias] ) ) {
2054                                 list( $joinType, $conds ) = $join_conds[$alias];
2055                                 $tableClause = $joinType;
2056                                 $tableClause .= ' ' . $joinedTable;
2057                                 if ( isset( $use_index[$alias] ) ) { // has USE INDEX?
2058                                         $use = $this->useIndexClause( implode( ',', (array)$use_index[$alias] ) );
2059                                         if ( $use != '' ) {
2060                                                 $tableClause .= ' ' . $use;
2061                                         }
2062                                 }
2063                                 if ( isset( $ignore_index[$alias] ) ) { // has IGNORE INDEX?
2064                                         $ignore = $this->ignoreIndexClause(
2065                                                 implode( ',', (array)$ignore_index[$alias] ) );
2066                                         if ( $ignore != '' ) {
2067                                                 $tableClause .= ' ' . $ignore;
2068                                         }
2069                                 }
2070                                 $on = $this->makeList( (array)$conds, self::LIST_AND );
2071                                 if ( $on != '' ) {
2072                                         $tableClause .= ' ON (' . $on . ')';
2073                                 }
2074
2075                                 $retJOIN[] = $tableClause;
2076                         } elseif ( isset( $use_index[$alias] ) ) {
2077                                 // Is there an INDEX clause for this table?
2078                                 $tableClause = $joinedTable;
2079                                 $tableClause .= ' ' . $this->useIndexClause(
2080                                                 implode( ',', (array)$use_index[$alias] )
2081                                         );
2082
2083                                 $ret[] = $tableClause;
2084                         } elseif ( isset( $ignore_index[$alias] ) ) {
2085                                 // Is there an INDEX clause for this table?
2086                                 $tableClause = $joinedTable;
2087                                 $tableClause .= ' ' . $this->ignoreIndexClause(
2088                                                 implode( ',', (array)$ignore_index[$alias] )
2089                                         );
2090
2091                                 $ret[] = $tableClause;
2092                         } else {
2093                                 $tableClause = $joinedTable;
2094
2095                                 $ret[] = $tableClause;
2096                         }
2097                 }
2098
2099                 // We can't separate explicit JOIN clauses with ',', use ' ' for those
2100                 $implicitJoins = !empty( $ret ) ? implode( ',', $ret ) : "";
2101                 $explicitJoins = !empty( $retJOIN ) ? implode( ' ', $retJOIN ) : "";
2102
2103                 // Compile our final table clause
2104                 return implode( ' ', [ $implicitJoins, $explicitJoins ] );
2105         }
2106
2107         /**
2108          * Allows for index remapping in queries where this is not consistent across DBMS
2109          *
2110          * @param string $index
2111          * @return string
2112          */
2113         protected function indexName( $index ) {
2114                 return $index;
2115         }
2116
2117         public function addQuotes( $s ) {
2118                 if ( $s instanceof Blob ) {
2119                         $s = $s->fetch();
2120                 }
2121                 if ( $s === null ) {
2122                         return 'NULL';
2123                 } elseif ( is_bool( $s ) ) {
2124                         return (int)$s;
2125                 } else {
2126                         # This will also quote numeric values. This should be harmless,
2127                         # and protects against weird problems that occur when they really
2128                         # _are_ strings such as article titles and string->number->string
2129                         # conversion is not 1:1.
2130                         return "'" . $this->strencode( $s ) . "'";
2131                 }
2132         }
2133
2134         /**
2135          * Quotes an identifier using `backticks` or "double quotes" depending on the database type.
2136          * MySQL uses `backticks` while basically everything else uses double quotes.
2137          * Since MySQL is the odd one out here the double quotes are our generic
2138          * and we implement backticks in DatabaseMysqlBase.
2139          *
2140          * @param string $s
2141          * @return string
2142          */
2143         public function addIdentifierQuotes( $s ) {
2144                 return '"' . str_replace( '"', '""', $s ) . '"';
2145         }
2146
2147         /**
2148          * Returns if the given identifier looks quoted or not according to
2149          * the database convention for quoting identifiers .
2150          *
2151          * @note Do not use this to determine if untrusted input is safe.
2152          *   A malicious user can trick this function.
2153          * @param string $name
2154          * @return bool
2155          */
2156         public function isQuotedIdentifier( $name ) {
2157                 return $name[0] == '"' && substr( $name, -1, 1 ) == '"';
2158         }
2159
2160         /**
2161          * @param string $s
2162          * @param string $escapeChar
2163          * @return string
2164          */
2165         protected function escapeLikeInternal( $s, $escapeChar = '`' ) {
2166                 return str_replace( [ $escapeChar, '%', '_' ],
2167                         [ "{$escapeChar}{$escapeChar}", "{$escapeChar}%", "{$escapeChar}_" ],
2168                         $s );
2169         }
2170
2171         public function buildLike() {
2172                 $params = func_get_args();
2173
2174                 if ( count( $params ) > 0 && is_array( $params[0] ) ) {
2175                         $params = $params[0];
2176                 }
2177
2178                 $s = '';
2179
2180                 // We use ` instead of \ as the default LIKE escape character, since addQuotes()
2181                 // may escape backslashes, creating problems of double escaping. The `
2182                 // character has good cross-DBMS compatibility, avoiding special operators
2183                 // in MS SQL like ^ and %
2184                 $escapeChar = '`';
2185
2186                 foreach ( $params as $value ) {
2187                         if ( $value instanceof LikeMatch ) {
2188                                 $s .= $value->toString();
2189                         } else {
2190                                 $s .= $this->escapeLikeInternal( $value, $escapeChar );
2191                         }
2192                 }
2193
2194                 return ' LIKE ' . $this->addQuotes( $s ) . ' ESCAPE ' . $this->addQuotes( $escapeChar ) . ' ';
2195         }
2196
2197         public function anyChar() {
2198                 return new LikeMatch( '_' );
2199         }
2200
2201         public function anyString() {
2202                 return new LikeMatch( '%' );
2203         }
2204
2205         public function nextSequenceValue( $seqName ) {
2206                 return null;
2207         }
2208
2209         /**
2210          * USE INDEX clause. Unlikely to be useful for anything but MySQL. This
2211          * is only needed because a) MySQL must be as efficient as possible due to
2212          * its use on Wikipedia, and b) MySQL 4.0 is kind of dumb sometimes about
2213          * which index to pick. Anyway, other databases might have different
2214          * indexes on a given table. So don't bother overriding this unless you're
2215          * MySQL.
2216          * @param string $index
2217          * @return string
2218          */
2219         public function useIndexClause( $index ) {
2220                 return '';
2221         }
2222
2223         /**
2224          * IGNORE INDEX clause. Unlikely to be useful for anything but MySQL. This
2225          * is only needed because a) MySQL must be as efficient as possible due to
2226          * its use on Wikipedia, and b) MySQL 4.0 is kind of dumb sometimes about
2227          * which index to pick. Anyway, other databases might have different
2228          * indexes on a given table. So don't bother overriding this unless you're
2229          * MySQL.
2230          * @param string $index
2231          * @return string
2232          */
2233         public function ignoreIndexClause( $index ) {
2234                 return '';
2235         }
2236
2237         public function replace( $table, $uniqueIndexes, $rows, $fname = __METHOD__ ) {
2238                 if ( count( $rows ) == 0 ) {
2239                         return;
2240                 }
2241
2242                 // Single row case
2243                 if ( !is_array( reset( $rows ) ) ) {
2244                         $rows = [ $rows ];
2245                 }
2246
2247                 $useTrx = !$this->trxLevel;
2248                 if ( $useTrx ) {
2249                         $this->begin( $fname, self::TRANSACTION_INTERNAL );
2250                 }
2251                 try {
2252                         $affectedRowCount = 0;
2253                         foreach ( $rows as $row ) {
2254                                 // Delete rows which collide with this one
2255                                 $indexWhereClauses = [];
2256                                 foreach ( $uniqueIndexes as $index ) {
2257                                         $indexColumns = (array)$index;
2258                                         $indexRowValues = array_intersect_key( $row, array_flip( $indexColumns ) );
2259                                         if ( count( $indexRowValues ) != count( $indexColumns ) ) {
2260                                                 throw new DBUnexpectedError(
2261                                                         $this,
2262                                                         'New record does not provide all values for unique key (' .
2263                                                         implode( ', ', $indexColumns ) . ')'
2264                                                 );
2265                                         } elseif ( in_array( null, $indexRowValues, true ) ) {
2266                                                 throw new DBUnexpectedError(
2267                                                         $this,
2268                                                         'New record has a null value for unique key (' .
2269                                                         implode( ', ', $indexColumns ) . ')'
2270                                                 );
2271                                         }
2272                                         $indexWhereClauses[] = $this->makeList( $indexRowValues, LIST_AND );
2273                                 }
2274
2275                                 if ( $indexWhereClauses ) {
2276                                         $this->delete( $table, $this->makeList( $indexWhereClauses, LIST_OR ), $fname );
2277                                         $affectedRowCount += $this->affectedRows();
2278                                 }
2279
2280                                 // Now insert the row
2281                                 $this->insert( $table, $row, $fname );
2282                                 $affectedRowCount += $this->affectedRows();
2283                         }
2284                 } catch ( Exception $e ) {
2285                         if ( $useTrx ) {
2286                                 $this->rollback( $fname, self::FLUSHING_INTERNAL );
2287                         }
2288                         throw $e;
2289                 }
2290                 if ( $useTrx ) {
2291                         $this->commit( $fname, self::FLUSHING_INTERNAL );
2292                 }
2293
2294                 $this->affectedRowCount = $affectedRowCount;
2295         }
2296
2297         /**
2298          * REPLACE query wrapper for MySQL and SQLite, which have a native REPLACE
2299          * statement.
2300          *
2301          * @param string $table Table name
2302          * @param array|string $rows Row(s) to insert
2303          * @param string $fname Caller function name
2304          *
2305          * @return ResultWrapper
2306          */
2307         protected function nativeReplace( $table, $rows, $fname ) {
2308                 $table = $this->tableName( $table );
2309
2310                 # Single row case
2311                 if ( !is_array( reset( $rows ) ) ) {
2312                         $rows = [ $rows ];
2313                 }
2314
2315                 $sql = "REPLACE INTO $table (" . implode( ',', array_keys( $rows[0] ) ) . ') VALUES ';
2316                 $first = true;
2317
2318                 foreach ( $rows as $row ) {
2319                         if ( $first ) {
2320                                 $first = false;
2321                         } else {
2322                                 $sql .= ',';
2323                         }
2324
2325                         $sql .= '(' . $this->makeList( $row ) . ')';
2326                 }
2327
2328                 return $this->query( $sql, $fname );
2329         }
2330
2331         public function upsert( $table, array $rows, array $uniqueIndexes, array $set,
2332                 $fname = __METHOD__
2333         ) {
2334                 if ( !count( $rows ) ) {
2335                         return true; // nothing to do
2336                 }
2337
2338                 if ( !is_array( reset( $rows ) ) ) {
2339                         $rows = [ $rows ];
2340                 }
2341
2342                 if ( count( $uniqueIndexes ) ) {
2343                         $clauses = []; // list WHERE clauses that each identify a single row
2344                         foreach ( $rows as $row ) {
2345                                 foreach ( $uniqueIndexes as $index ) {
2346                                         $index = is_array( $index ) ? $index : [ $index ]; // columns
2347                                         $rowKey = []; // unique key to this row
2348                                         foreach ( $index as $column ) {
2349                                                 $rowKey[$column] = $row[$column];
2350                                         }
2351                                         $clauses[] = $this->makeList( $rowKey, self::LIST_AND );
2352                                 }
2353                         }
2354                         $where = [ $this->makeList( $clauses, self::LIST_OR ) ];
2355                 } else {
2356                         $where = false;
2357                 }
2358
2359                 $affectedRowCount = 0;
2360                 $useTrx = !$this->trxLevel;
2361                 if ( $useTrx ) {
2362                         $this->begin( $fname, self::TRANSACTION_INTERNAL );
2363                 }
2364                 try {
2365                         # Update any existing conflicting row(s)
2366                         if ( $where !== false ) {
2367                                 $ok = $this->update( $table, $set, $where, $fname );
2368                                 $affectedRowCount += $this->affectedRows();
2369                         } else {
2370                                 $ok = true;
2371                         }
2372                         # Now insert any non-conflicting row(s)
2373                         $ok = $this->insert( $table, $rows, $fname, [ 'IGNORE' ] ) && $ok;
2374                         $affectedRowCount += $this->affectedRows();
2375                 } catch ( Exception $e ) {
2376                         if ( $useTrx ) {
2377                                 $this->rollback( $fname, self::FLUSHING_INTERNAL );
2378                         }
2379                         throw $e;
2380                 }
2381                 if ( $useTrx ) {
2382                         $this->commit( $fname, self::FLUSHING_INTERNAL );
2383                 }
2384                 $this->affectedRowCount = $affectedRowCount;
2385
2386                 return $ok;
2387         }
2388
2389         public function deleteJoin( $delTable, $joinTable, $delVar, $joinVar, $conds,
2390                 $fname = __METHOD__
2391         ) {
2392                 if ( !$conds ) {
2393                         throw new DBUnexpectedError( $this, __METHOD__ . ' called with empty $conds' );
2394                 }
2395
2396                 $delTable = $this->tableName( $delTable );
2397                 $joinTable = $this->tableName( $joinTable );
2398                 $sql = "DELETE FROM $delTable WHERE $delVar IN (SELECT $joinVar FROM $joinTable ";
2399                 if ( $conds != '*' ) {
2400                         $sql .= 'WHERE ' . $this->makeList( $conds, self::LIST_AND );
2401                 }
2402                 $sql .= ')';
2403
2404                 $this->query( $sql, $fname );
2405         }
2406
2407         public function textFieldSize( $table, $field ) {
2408                 $table = $this->tableName( $table );
2409                 $sql = "SHOW COLUMNS FROM $table LIKE \"$field\";";
2410                 $res = $this->query( $sql, __METHOD__ );
2411                 $row = $this->fetchObject( $res );
2412
2413                 $m = [];
2414
2415                 if ( preg_match( '/\((.*)\)/', $row->Type, $m ) ) {
2416                         $size = $m[1];
2417                 } else {
2418                         $size = -1;
2419                 }
2420
2421                 return $size;
2422         }
2423
2424         public function delete( $table, $conds, $fname = __METHOD__ ) {
2425                 if ( !$conds ) {
2426                         throw new DBUnexpectedError( $this, __METHOD__ . ' called with no conditions' );
2427                 }
2428
2429                 $table = $this->tableName( $table );
2430                 $sql = "DELETE FROM $table";
2431
2432                 if ( $conds != '*' ) {
2433                         if ( is_array( $conds ) ) {
2434                                 $conds = $this->makeList( $conds, self::LIST_AND );
2435                         }
2436                         $sql .= ' WHERE ' . $conds;
2437                 }
2438
2439                 return $this->query( $sql, $fname );
2440         }
2441
2442         public function insertSelect(
2443                 $destTable, $srcTable, $varMap, $conds,
2444                 $fname = __METHOD__, $insertOptions = [], $selectOptions = [], $selectJoinConds = []
2445         ) {
2446                 if ( $this->cliMode ) {
2447                         // For massive migrations with downtime, we don't want to select everything
2448                         // into memory and OOM, so do all this native on the server side if possible.
2449                         return $this->nativeInsertSelect(
2450                                 $destTable,
2451                                 $srcTable,
2452                                 $varMap,
2453                                 $conds,
2454                                 $fname,
2455                                 $insertOptions,
2456                                 $selectOptions,
2457                                 $selectJoinConds
2458                         );
2459                 }
2460
2461                 return $this->nonNativeInsertSelect(
2462                         $destTable,
2463                         $srcTable,
2464                         $varMap,
2465                         $conds,
2466                         $fname,
2467                         $insertOptions,
2468                         $selectOptions,
2469                         $selectJoinConds
2470                 );
2471         }
2472
2473         /**
2474          * Implementation of insertSelect() based on select() and insert()
2475          *
2476          * @see IDatabase::insertSelect()
2477          * @since 1.30
2478          * @param string $destTable
2479          * @param string|array $srcTable
2480          * @param array $varMap
2481          * @param array $conds
2482          * @param string $fname
2483          * @param array $insertOptions
2484          * @param array $selectOptions
2485          * @param array $selectJoinConds
2486          * @return bool
2487          */
2488         protected function nonNativeInsertSelect( $destTable, $srcTable, $varMap, $conds,
2489                 $fname = __METHOD__,
2490                 $insertOptions = [], $selectOptions = [], $selectJoinConds = []
2491         ) {
2492                 // For web requests, do a locking SELECT and then INSERT. This puts the SELECT burden
2493                 // on only the master (without needing row-based-replication). It also makes it easy to
2494                 // know how big the INSERT is going to be.
2495                 $fields = [];
2496                 foreach ( $varMap as $dstColumn => $sourceColumnOrSql ) {
2497                         $fields[] = $this->fieldNameWithAlias( $sourceColumnOrSql, $dstColumn );
2498                 }
2499                 $selectOptions[] = 'FOR UPDATE';
2500                 $res = $this->select(
2501                         $srcTable, implode( ',', $fields ), $conds, $fname, $selectOptions, $selectJoinConds
2502                 );
2503                 if ( !$res ) {
2504                         return false;
2505                 }
2506
2507                 $rows = [];
2508                 foreach ( $res as $row ) {
2509                         $rows[] = (array)$row;
2510                 }
2511
2512                 return $this->insert( $destTable, $rows, $fname, $insertOptions );
2513         }
2514
2515         /**
2516          * Native server-side implementation of insertSelect() for situations where
2517          * we don't want to select everything into memory
2518          *
2519          * @see IDatabase::insertSelect()
2520          * @param string $destTable
2521          * @param string|array $srcTable
2522          * @param array $varMap
2523          * @param array $conds
2524          * @param string $fname
2525          * @param array $insertOptions
2526          * @param array $selectOptions
2527          * @param array $selectJoinConds
2528          * @return bool
2529          */
2530         protected function nativeInsertSelect( $destTable, $srcTable, $varMap, $conds,
2531                 $fname = __METHOD__,
2532                 $insertOptions = [], $selectOptions = [], $selectJoinConds = []
2533         ) {
2534                 $destTable = $this->tableName( $destTable );
2535
2536                 if ( !is_array( $insertOptions ) ) {
2537                         $insertOptions = [ $insertOptions ];
2538                 }
2539
2540                 $insertOptions = $this->makeInsertOptions( $insertOptions );
2541
2542                 $selectSql = $this->selectSQLText(
2543                         $srcTable,
2544                         array_values( $varMap ),
2545                         $conds,
2546                         $fname,
2547                         $selectOptions,
2548                         $selectJoinConds
2549                 );
2550
2551                 $sql = "INSERT $insertOptions" .
2552                         " INTO $destTable (" . implode( ',', array_keys( $varMap ) ) . ') ' .
2553                         $selectSql;
2554
2555                 return $this->query( $sql, $fname );
2556         }
2557
2558         /**
2559          * Construct a LIMIT query with optional offset. This is used for query
2560          * pages. The SQL should be adjusted so that only the first $limit rows
2561          * are returned. If $offset is provided as well, then the first $offset
2562          * rows should be discarded, and the next $limit rows should be returned.
2563          * If the result of the query is not ordered, then the rows to be returned
2564          * are theoretically arbitrary.
2565          *
2566          * $sql is expected to be a SELECT, if that makes a difference.
2567          *
2568          * The version provided by default works in MySQL and SQLite. It will very
2569          * likely need to be overridden for most other DBMSes.
2570          *
2571          * @param string $sql SQL query we will append the limit too
2572          * @param int $limit The SQL limit
2573          * @param int|bool $offset The SQL offset (default false)
2574          * @throws DBUnexpectedError
2575          * @return string
2576          */
2577         public function limitResult( $sql, $limit, $offset = false ) {
2578                 if ( !is_numeric( $limit ) ) {
2579                         throw new DBUnexpectedError( $this,
2580                                 "Invalid non-numeric limit passed to limitResult()\n" );
2581                 }
2582
2583                 return "$sql LIMIT "
2584                 . ( ( is_numeric( $offset ) && $offset != 0 ) ? "{$offset}," : "" )
2585                 . "{$limit} ";
2586         }
2587
2588         public function unionSupportsOrderAndLimit() {
2589                 return true; // True for almost every DB supported
2590         }
2591
2592         public function unionQueries( $sqls, $all ) {
2593                 $glue = $all ? ') UNION ALL (' : ') UNION (';
2594
2595                 return '(' . implode( $glue, $sqls ) . ')';
2596         }
2597
2598         public function unionConditionPermutations(
2599                 $table, $vars, array $permute_conds, $extra_conds = '', $fname = __METHOD__,
2600                 $options = [], $join_conds = []
2601         ) {
2602                 // First, build the Cartesian product of $permute_conds
2603                 $conds = [ [] ];
2604                 foreach ( $permute_conds as $field => $values ) {
2605                         if ( !$values ) {
2606                                 // Skip empty $values
2607                                 continue;
2608                         }
2609                         $values = array_unique( $values ); // For sanity
2610                         $newConds = [];
2611                         foreach ( $conds as $cond ) {
2612                                 foreach ( $values as $value ) {
2613                                         $cond[$field] = $value;
2614                                         $newConds[] = $cond; // Arrays are by-value, not by-reference, so this works
2615                                 }
2616                         }
2617                         $conds = $newConds;
2618                 }
2619
2620                 $extra_conds = $extra_conds === '' ? [] : (array)$extra_conds;
2621
2622                 // If there's just one condition and no subordering, hand off to
2623                 // selectSQLText directly.
2624                 if ( count( $conds ) === 1 &&
2625                         ( !isset( $options['INNER ORDER BY'] ) || !$this->unionSupportsOrderAndLimit() )
2626                 ) {
2627                         return $this->selectSQLText(
2628                                 $table, $vars, $conds[0] + $extra_conds, $fname, $options, $join_conds
2629                         );
2630                 }
2631
2632                 // Otherwise, we need to pull out the order and limit to apply after
2633                 // the union. Then build the SQL queries for each set of conditions in
2634                 // $conds. Then union them together (using UNION ALL, because the
2635                 // product *should* already be distinct).
2636                 $orderBy = $this->makeOrderBy( $options );
2637                 $limit = isset( $options['LIMIT'] ) ? $options['LIMIT'] : null;
2638                 $offset = isset( $options['OFFSET'] ) ? $options['OFFSET'] : false;
2639                 $all = empty( $options['NOTALL'] ) && !in_array( 'NOTALL', $options );
2640                 if ( !$this->unionSupportsOrderAndLimit() ) {
2641                         unset( $options['ORDER BY'], $options['LIMIT'], $options['OFFSET'] );
2642                 } else {
2643                         if ( array_key_exists( 'INNER ORDER BY', $options ) ) {
2644                                 $options['ORDER BY'] = $options['INNER ORDER BY'];
2645                         }
2646                         if ( $limit !== null && is_numeric( $offset ) && $offset != 0 ) {
2647                                 // We need to increase the limit by the offset rather than
2648                                 // using the offset directly, otherwise it'll skip incorrectly
2649                                 // in the subqueries.
2650                                 $options['LIMIT'] = $limit + $offset;
2651                                 unset( $options['OFFSET'] );
2652                         }
2653                 }
2654
2655                 $sqls = [];
2656                 foreach ( $conds as $cond ) {
2657                         $sqls[] = $this->selectSQLText(
2658                                 $table, $vars, $cond + $extra_conds, $fname, $options, $join_conds
2659                         );
2660                 }
2661                 $sql = $this->unionQueries( $sqls, $all ) . $orderBy;
2662                 if ( $limit !== null ) {
2663                         $sql = $this->limitResult( $sql, $limit, $offset );
2664                 }
2665
2666                 return $sql;
2667         }
2668
2669         public function conditional( $cond, $trueVal, $falseVal ) {
2670                 if ( is_array( $cond ) ) {
2671                         $cond = $this->makeList( $cond, self::LIST_AND );
2672                 }
2673
2674                 return " (CASE WHEN $cond THEN $trueVal ELSE $falseVal END) ";
2675         }
2676
2677         public function strreplace( $orig, $old, $new ) {
2678                 return "REPLACE({$orig}, {$old}, {$new})";
2679         }
2680
2681         public function getServerUptime() {
2682                 return 0;
2683         }
2684
2685         public function wasDeadlock() {
2686                 return false;
2687         }
2688
2689         public function wasLockTimeout() {
2690                 return false;
2691         }
2692
2693         public function wasErrorReissuable() {
2694                 return false;
2695         }
2696
2697         public function wasReadOnlyError() {
2698                 return false;
2699         }
2700
2701         /**
2702          * Do not use this method outside of Database/DBError classes
2703          *
2704          * @param int|string $errno
2705          * @return bool Whether the given query error was a connection drop
2706          */
2707         public function wasConnectionError( $errno ) {
2708                 return false;
2709         }
2710
2711         public function deadlockLoop() {
2712                 $args = func_get_args();
2713                 $function = array_shift( $args );
2714                 $tries = self::DEADLOCK_TRIES;
2715
2716                 $this->begin( __METHOD__ );
2717
2718                 $retVal = null;
2719                 /** @var Exception $e */
2720                 $e = null;
2721                 do {
2722                         try {
2723                                 $retVal = call_user_func_array( $function, $args );
2724                                 break;
2725                         } catch ( DBQueryError $e ) {
2726                                 if ( $this->wasDeadlock() ) {
2727                                         // Retry after a randomized delay
2728                                         usleep( mt_rand( self::DEADLOCK_DELAY_MIN, self::DEADLOCK_DELAY_MAX ) );
2729                                 } else {
2730                                         // Throw the error back up
2731                                         throw $e;
2732                                 }
2733                         }
2734                 } while ( --$tries > 0 );
2735
2736                 if ( $tries <= 0 ) {
2737                         // Too many deadlocks; give up
2738                         $this->rollback( __METHOD__ );
2739                         throw $e;
2740                 } else {
2741                         $this->commit( __METHOD__ );
2742
2743                         return $retVal;
2744                 }
2745         }
2746
2747         public function masterPosWait( DBMasterPos $pos, $timeout ) {
2748                 # Real waits are implemented in the subclass.
2749                 return 0;
2750         }
2751
2752         public function getReplicaPos() {
2753                 # Stub
2754                 return false;
2755         }
2756
2757         public function getMasterPos() {
2758                 # Stub
2759                 return false;
2760         }
2761
2762         public function serverIsReadOnly() {
2763                 return false;
2764         }
2765
2766         final public function onTransactionResolution( callable $callback, $fname = __METHOD__ ) {
2767                 if ( !$this->trxLevel ) {
2768                         throw new DBUnexpectedError( $this, "No transaction is active." );
2769                 }
2770                 $this->trxEndCallbacks[] = [ $callback, $fname ];
2771         }
2772
2773         final public function onTransactionIdle( callable $callback, $fname = __METHOD__ ) {
2774                 $this->trxIdleCallbacks[] = [ $callback, $fname ];
2775                 if ( !$this->trxLevel ) {
2776                         $this->runOnTransactionIdleCallbacks( self::TRIGGER_IDLE );
2777                 }
2778         }
2779
2780         final public function onTransactionPreCommitOrIdle( callable $callback, $fname = __METHOD__ ) {
2781                 if ( $this->trxLevel || $this->getFlag( self::DBO_TRX ) ) {
2782                         // As long as DBO_TRX is set, writes will accumulate until the load balancer issues
2783                         // an implicit commit of all peer databases. This is true even if a transaction has
2784                         // not yet been triggered by writes; make sure $callback runs *after* any such writes.
2785                         $this->trxPreCommitCallbacks[] = [ $callback, $fname ];
2786                 } else {
2787                         // No transaction is active nor will start implicitly, so make one for this callback
2788                         $this->startAtomic( __METHOD__ );
2789                         try {
2790                                 call_user_func( $callback );
2791                                 $this->endAtomic( __METHOD__ );
2792                         } catch ( Exception $e ) {
2793                                 $this->rollback( __METHOD__, self::FLUSHING_INTERNAL );
2794                                 throw $e;
2795                         }
2796                 }
2797         }
2798
2799         final public function setTransactionListener( $name, callable $callback = null ) {
2800                 if ( $callback ) {
2801                         $this->trxRecurringCallbacks[$name] = $callback;
2802                 } else {
2803                         unset( $this->trxRecurringCallbacks[$name] );
2804                 }
2805         }
2806
2807         /**
2808          * Whether to disable running of post-COMMIT/ROLLBACK callbacks
2809          *
2810          * This method should not be used outside of Database/LoadBalancer
2811          *
2812          * @param bool $suppress
2813          * @since 1.28
2814          */
2815         final public function setTrxEndCallbackSuppression( $suppress ) {
2816                 $this->trxEndCallbacksSuppressed = $suppress;
2817         }
2818
2819         /**
2820          * Actually run and consume any "on transaction idle/resolution" callbacks.
2821          *
2822          * This method should not be used outside of Database/LoadBalancer
2823          *
2824          * @param int $trigger IDatabase::TRIGGER_* constant
2825          * @since 1.20
2826          * @throws Exception
2827          */
2828         public function runOnTransactionIdleCallbacks( $trigger ) {
2829                 if ( $this->trxEndCallbacksSuppressed ) {
2830                         return;
2831                 }
2832
2833                 $autoTrx = $this->getFlag( self::DBO_TRX ); // automatic begin() enabled?
2834                 /** @var Exception $e */
2835                 $e = null; // first exception
2836                 do { // callbacks may add callbacks :)
2837                         $callbacks = array_merge(
2838                                 $this->trxIdleCallbacks,
2839                                 $this->trxEndCallbacks // include "transaction resolution" callbacks
2840                         );
2841                         $this->trxIdleCallbacks = []; // consumed (and recursion guard)
2842                         $this->trxEndCallbacks = []; // consumed (recursion guard)
2843                         foreach ( $callbacks as $callback ) {
2844                                 try {
2845                                         list( $phpCallback ) = $callback;
2846                                         $this->clearFlag( self::DBO_TRX ); // make each query its own transaction
2847                                         call_user_func_array( $phpCallback, [ $trigger ] );
2848                                         if ( $autoTrx ) {
2849                                                 $this->setFlag( self::DBO_TRX ); // restore automatic begin()
2850                                         } else {
2851                                                 $this->clearFlag( self::DBO_TRX ); // restore auto-commit
2852                                         }
2853                                 } catch ( Exception $ex ) {
2854                                         call_user_func( $this->errorLogger, $ex );
2855                                         $e = $e ?: $ex;
2856                                         // Some callbacks may use startAtomic/endAtomic, so make sure
2857                                         // their transactions are ended so other callbacks don't fail
2858                                         if ( $this->trxLevel() ) {
2859                                                 $this->rollback( __METHOD__, self::FLUSHING_INTERNAL );
2860                                         }
2861                                 }
2862                         }
2863                 } while ( count( $this->trxIdleCallbacks ) );
2864
2865                 if ( $e instanceof Exception ) {
2866                         throw $e; // re-throw any first exception
2867                 }
2868         }
2869
2870         /**
2871          * Actually run and consume any "on transaction pre-commit" callbacks.
2872          *
2873          * This method should not be used outside of Database/LoadBalancer
2874          *
2875          * @since 1.22
2876          * @throws Exception
2877          */
2878         public function runOnTransactionPreCommitCallbacks() {
2879                 $e = null; // first exception
2880                 do { // callbacks may add callbacks :)
2881                         $callbacks = $this->trxPreCommitCallbacks;
2882                         $this->trxPreCommitCallbacks = []; // consumed (and recursion guard)
2883                         foreach ( $callbacks as $callback ) {
2884                                 try {
2885                                         list( $phpCallback ) = $callback;
2886                                         call_user_func( $phpCallback );
2887                                 } catch ( Exception $ex ) {
2888                                         call_user_func( $this->errorLogger, $ex );
2889                                         $e = $e ?: $ex;
2890                                 }
2891                         }
2892                 } while ( count( $this->trxPreCommitCallbacks ) );
2893
2894                 if ( $e instanceof Exception ) {
2895                         throw $e; // re-throw any first exception
2896                 }
2897         }
2898
2899         /**
2900          * Actually run any "transaction listener" callbacks.
2901          *
2902          * This method should not be used outside of Database/LoadBalancer
2903          *
2904          * @param int $trigger IDatabase::TRIGGER_* constant
2905          * @throws Exception
2906          * @since 1.20
2907          */
2908         public function runTransactionListenerCallbacks( $trigger ) {
2909                 if ( $this->trxEndCallbacksSuppressed ) {
2910                         return;
2911                 }
2912
2913                 /** @var Exception $e */
2914                 $e = null; // first exception
2915
2916                 foreach ( $this->trxRecurringCallbacks as $phpCallback ) {
2917                         try {
2918                                 $phpCallback( $trigger, $this );
2919                         } catch ( Exception $ex ) {
2920                                 call_user_func( $this->errorLogger, $ex );
2921                                 $e = $e ?: $ex;
2922                         }
2923                 }
2924
2925                 if ( $e instanceof Exception ) {
2926                         throw $e; // re-throw any first exception
2927                 }
2928         }
2929
2930         final public function startAtomic( $fname = __METHOD__ ) {
2931                 if ( !$this->trxLevel ) {
2932                         $this->begin( $fname, self::TRANSACTION_INTERNAL );
2933                         // If DBO_TRX is set, a series of startAtomic/endAtomic pairs will result
2934                         // in all changes being in one transaction to keep requests transactional.
2935                         if ( !$this->getFlag( self::DBO_TRX ) ) {
2936                                 $this->trxAutomaticAtomic = true;
2937                         }
2938                 }
2939
2940                 $this->trxAtomicLevels[] = $fname;
2941         }
2942
2943         final public function endAtomic( $fname = __METHOD__ ) {
2944                 if ( !$this->trxLevel ) {
2945                         throw new DBUnexpectedError( $this, "No atomic transaction is open (got $fname)." );
2946                 }
2947                 if ( !$this->trxAtomicLevels ||
2948                         array_pop( $this->trxAtomicLevels ) !== $fname
2949                 ) {
2950                         throw new DBUnexpectedError( $this, "Invalid atomic section ended (got $fname)." );
2951                 }
2952
2953                 if ( !$this->trxAtomicLevels && $this->trxAutomaticAtomic ) {
2954                         $this->commit( $fname, self::FLUSHING_INTERNAL );
2955                 }
2956         }
2957
2958         final public function doAtomicSection( $fname, callable $callback ) {
2959                 $this->startAtomic( $fname );
2960                 try {
2961                         $res = call_user_func_array( $callback, [ $this, $fname ] );
2962                 } catch ( Exception $e ) {
2963                         $this->rollback( $fname, self::FLUSHING_INTERNAL );
2964                         throw $e;
2965                 }
2966                 $this->endAtomic( $fname );
2967
2968                 return $res;
2969         }
2970
2971         final public function begin( $fname = __METHOD__, $mode = self::TRANSACTION_EXPLICIT ) {
2972                 // Protect against mismatched atomic section, transaction nesting, and snapshot loss
2973                 if ( $this->trxLevel ) {
2974                         if ( $this->trxAtomicLevels ) {
2975                                 $levels = implode( ', ', $this->trxAtomicLevels );
2976                                 $msg = "$fname: Got explicit BEGIN while atomic section(s) $levels are open.";
2977                                 throw new DBUnexpectedError( $this, $msg );
2978                         } elseif ( !$this->trxAutomatic ) {
2979                                 $msg = "$fname: Explicit transaction already active (from {$this->trxFname}).";
2980                                 throw new DBUnexpectedError( $this, $msg );
2981                         } else {
2982                                 // @TODO: make this an exception at some point
2983                                 $msg = "$fname: Implicit transaction already active (from {$this->trxFname}).";
2984                                 $this->queryLogger->error( $msg );
2985                                 return; // join the main transaction set
2986                         }
2987                 } elseif ( $this->getFlag( self::DBO_TRX ) && $mode !== self::TRANSACTION_INTERNAL ) {
2988                         // @TODO: make this an exception at some point
2989                         $msg = "$fname: Implicit transaction expected (DBO_TRX set).";
2990                         $this->queryLogger->error( $msg );
2991                         return; // let any writes be in the main transaction
2992                 }
2993
2994                 // Avoid fatals if close() was called
2995                 $this->assertOpen();
2996
2997                 $this->doBegin( $fname );
2998                 $this->trxTimestamp = microtime( true );
2999                 $this->trxFname = $fname;
3000                 $this->trxDoneWrites = false;
3001                 $this->trxAutomaticAtomic = false;
3002                 $this->trxAtomicLevels = [];
3003                 $this->trxShortId = sprintf( '%06x', mt_rand( 0, 0xffffff ) );
3004                 $this->trxWriteDuration = 0.0;
3005                 $this->trxWriteQueryCount = 0;
3006                 $this->trxWriteAffectedRows = 0;
3007                 $this->trxWriteAdjDuration = 0.0;
3008                 $this->trxWriteAdjQueryCount = 0;
3009                 $this->trxWriteCallers = [];
3010                 // First SELECT after BEGIN will establish the snapshot in REPEATABLE-READ.
3011                 // Get an estimate of the replica DB lag before then, treating estimate staleness
3012                 // as lag itself just to be safe
3013                 $status = $this->getApproximateLagStatus();
3014                 $this->trxReplicaLag = $status['lag'] + ( microtime( true ) - $status['since'] );
3015                 // T147697: make explicitTrxActive() return true until begin() finishes. This way, no
3016                 // caller will think its OK to muck around with the transaction just because startAtomic()
3017                 // has not yet completed (e.g. setting trxAtomicLevels).
3018                 $this->trxAutomatic = ( $mode === self::TRANSACTION_INTERNAL );
3019         }
3020
3021         /**
3022          * Issues the BEGIN command to the database server.
3023          *
3024          * @see Database::begin()
3025          * @param string $fname
3026          */
3027         protected function doBegin( $fname ) {
3028                 $this->query( 'BEGIN', $fname );
3029                 $this->trxLevel = 1;
3030         }
3031
3032         final public function commit( $fname = __METHOD__, $flush = '' ) {
3033                 if ( $this->trxLevel && $this->trxAtomicLevels ) {
3034                         // There are still atomic sections open. This cannot be ignored
3035                         $levels = implode( ', ', $this->trxAtomicLevels );
3036                         throw new DBUnexpectedError(
3037                                 $this,
3038                                 "$fname: Got COMMIT while atomic sections $levels are still open."
3039                         );
3040                 }
3041
3042                 if ( $flush === self::FLUSHING_INTERNAL || $flush === self::FLUSHING_ALL_PEERS ) {
3043                         if ( !$this->trxLevel ) {
3044                                 return; // nothing to do
3045                         } elseif ( !$this->trxAutomatic ) {
3046                                 throw new DBUnexpectedError(
3047                                         $this,
3048                                         "$fname: Flushing an explicit transaction, getting out of sync."
3049                                 );
3050                         }
3051                 } else {
3052                         if ( !$this->trxLevel ) {
3053                                 $this->queryLogger->error(
3054                                         "$fname: No transaction to commit, something got out of sync." );
3055                                 return; // nothing to do
3056                         } elseif ( $this->trxAutomatic ) {
3057                                 // @TODO: make this an exception at some point
3058                                 $msg = "$fname: Explicit commit of implicit transaction.";
3059                                 $this->queryLogger->error( $msg );
3060                                 return; // wait for the main transaction set commit round
3061                         }
3062                 }
3063
3064                 // Avoid fatals if close() was called
3065                 $this->assertOpen();
3066
3067                 $this->runOnTransactionPreCommitCallbacks();
3068                 $writeTime = $this->pendingWriteQueryDuration( self::ESTIMATE_DB_APPLY );
3069                 $this->doCommit( $fname );
3070                 if ( $this->trxDoneWrites ) {
3071                         $this->lastWriteTime = microtime( true );
3072                         $this->trxProfiler->transactionWritingOut(
3073                                 $this->server,
3074                                 $this->dbName,
3075                                 $this->trxShortId,
3076                                 $writeTime,
3077                                 $this->trxWriteAffectedRows
3078                         );
3079                 }
3080
3081                 $this->runOnTransactionIdleCallbacks( self::TRIGGER_COMMIT );
3082                 $this->runTransactionListenerCallbacks( self::TRIGGER_COMMIT );
3083         }
3084
3085         /**
3086          * Issues the COMMIT command to the database server.
3087          *
3088          * @see Database::commit()
3089          * @param string $fname
3090          */
3091         protected function doCommit( $fname ) {
3092                 if ( $this->trxLevel ) {
3093                         $this->query( 'COMMIT', $fname );
3094                         $this->trxLevel = 0;
3095                 }
3096         }
3097
3098         final public function rollback( $fname = __METHOD__, $flush = '' ) {
3099                 if ( $flush === self::FLUSHING_INTERNAL || $flush === self::FLUSHING_ALL_PEERS ) {
3100                         if ( !$this->trxLevel ) {
3101                                 return; // nothing to do
3102                         }
3103                 } else {
3104                         if ( !$this->trxLevel ) {
3105                                 $this->queryLogger->error(
3106                                         "$fname: No transaction to rollback, something got out of sync." );
3107                                 return; // nothing to do
3108                         } elseif ( $this->getFlag( self::DBO_TRX ) ) {
3109                                 throw new DBUnexpectedError(
3110                                         $this,
3111                                         "$fname: Expected mass rollback of all peer databases (DBO_TRX set)."
3112                                 );
3113                         }
3114                 }
3115
3116                 // Avoid fatals if close() was called
3117                 $this->assertOpen();
3118
3119                 $this->doRollback( $fname );
3120                 $this->trxAtomicLevels = [];
3121                 if ( $this->trxDoneWrites ) {
3122                         $this->trxProfiler->transactionWritingOut(
3123                                 $this->server,
3124                                 $this->dbName,
3125                                 $this->trxShortId
3126                         );
3127                 }
3128
3129                 $this->trxIdleCallbacks = []; // clear
3130                 $this->trxPreCommitCallbacks = []; // clear
3131                 try {
3132                         $this->runOnTransactionIdleCallbacks( self::TRIGGER_ROLLBACK );
3133                 } catch ( Exception $e ) {
3134                         // already logged; finish and let LoadBalancer move on during mass-rollback
3135                 }
3136                 try {
3137                         $this->runTransactionListenerCallbacks( self::TRIGGER_ROLLBACK );
3138                 } catch ( Exception $e ) {
3139                         // already logged; let LoadBalancer move on during mass-rollback
3140                 }
3141         }
3142
3143         /**
3144          * Issues the ROLLBACK command to the database server.
3145          *
3146          * @see Database::rollback()
3147          * @param string $fname
3148          */
3149         protected function doRollback( $fname ) {
3150                 if ( $this->trxLevel ) {
3151                         # Disconnects cause rollback anyway, so ignore those errors
3152                         $ignoreErrors = true;
3153                         $this->query( 'ROLLBACK', $fname, $ignoreErrors );
3154                         $this->trxLevel = 0;
3155                 }
3156         }
3157
3158         public function flushSnapshot( $fname = __METHOD__ ) {
3159                 if ( $this->writesOrCallbacksPending() || $this->explicitTrxActive() ) {
3160                         // This only flushes transactions to clear snapshots, not to write data
3161                         $fnames = implode( ', ', $this->pendingWriteAndCallbackCallers() );
3162                         throw new DBUnexpectedError(
3163                                 $this,
3164                                 "$fname: Cannot flush snapshot because writes are pending ($fnames)."
3165                         );
3166                 }
3167
3168                 $this->commit( $fname, self::FLUSHING_INTERNAL );
3169         }
3170
3171         public function explicitTrxActive() {
3172                 return $this->trxLevel && ( $this->trxAtomicLevels || !$this->trxAutomatic );
3173         }
3174
3175         public function duplicateTableStructure(
3176                 $oldName, $newName, $temporary = false, $fname = __METHOD__
3177         ) {
3178                 throw new RuntimeException( __METHOD__ . ' is not implemented in descendant class' );
3179         }
3180
3181         public function listTables( $prefix = null, $fname = __METHOD__ ) {
3182                 throw new RuntimeException( __METHOD__ . ' is not implemented in descendant class' );
3183         }
3184
3185         public function listViews( $prefix = null, $fname = __METHOD__ ) {
3186                 throw new RuntimeException( __METHOD__ . ' is not implemented in descendant class' );
3187         }
3188
3189         public function timestamp( $ts = 0 ) {
3190                 $t = new ConvertibleTimestamp( $ts );
3191                 // Let errors bubble up to avoid putting garbage in the DB
3192                 return $t->getTimestamp( TS_MW );
3193         }
3194
3195         public function timestampOrNull( $ts = null ) {
3196                 if ( is_null( $ts ) ) {
3197                         return null;
3198                 } else {
3199                         return $this->timestamp( $ts );
3200                 }
3201         }
3202
3203         public function affectedRows() {
3204                 return ( $this->affectedRowCount === null )
3205                         ? $this->fetchAffectedRowCount() // default to driver value
3206                         : $this->affectedRowCount;
3207         }
3208
3209         /**
3210          * @return int Number of retrieved rows according to the driver
3211          */
3212         abstract protected function fetchAffectedRowCount();
3213
3214         /**
3215          * Take the result from a query, and wrap it in a ResultWrapper if
3216          * necessary. Boolean values are passed through as is, to indicate success
3217          * of write queries or failure.
3218          *
3219          * Once upon a time, Database::query() returned a bare MySQL result
3220          * resource, and it was necessary to call this function to convert it to
3221          * a wrapper. Nowadays, raw database objects are never exposed to external
3222          * callers, so this is unnecessary in external code.
3223          *
3224          * @param bool|ResultWrapper|resource|object $result
3225          * @return bool|ResultWrapper
3226          */
3227         protected function resultObject( $result ) {
3228                 if ( !$result ) {
3229                         return false;
3230                 } elseif ( $result instanceof ResultWrapper ) {
3231                         return $result;
3232                 } elseif ( $result === true ) {
3233                         // Successful write query
3234                         return $result;
3235                 } else {
3236                         return new ResultWrapper( $this, $result );
3237                 }
3238         }
3239
3240         public function ping( &$rtt = null ) {
3241                 // Avoid hitting the server if it was hit recently
3242                 if ( $this->isOpen() && ( microtime( true ) - $this->lastPing ) < self::PING_TTL ) {
3243                         if ( !func_num_args() || $this->rttEstimate > 0 ) {
3244                                 $rtt = $this->rttEstimate;
3245                                 return true; // don't care about $rtt
3246                         }
3247                 }
3248
3249                 // This will reconnect if possible or return false if not
3250                 $this->clearFlag( self::DBO_TRX, self::REMEMBER_PRIOR );
3251                 $ok = ( $this->query( self::PING_QUERY, __METHOD__, true ) !== false );
3252                 $this->restoreFlags( self::RESTORE_PRIOR );
3253
3254                 if ( $ok ) {
3255                         $rtt = $this->rttEstimate;
3256                 }
3257
3258                 return $ok;
3259         }
3260
3261         /**
3262          * Close existing database connection and open a new connection
3263          *
3264          * @return bool True if new connection is opened successfully, false if error
3265          */
3266         protected function reconnect() {
3267                 $this->closeConnection();
3268                 $this->opened = false;
3269                 $this->conn = false;
3270                 try {
3271                         $this->open( $this->server, $this->user, $this->password, $this->dbName );
3272                         $this->lastPing = microtime( true );
3273                         $ok = true;
3274                 } catch ( DBConnectionError $e ) {
3275                         $ok = false;
3276                 }
3277
3278                 return $ok;
3279         }
3280
3281         public function getSessionLagStatus() {
3282                 return $this->getTransactionLagStatus() ?: $this->getApproximateLagStatus();
3283         }
3284
3285         /**
3286          * Get the replica DB lag when the current transaction started
3287          *
3288          * This is useful when transactions might use snapshot isolation
3289          * (e.g. REPEATABLE-READ in innodb), so the "real" lag of that data
3290          * is this lag plus transaction duration. If they don't, it is still
3291          * safe to be pessimistic. This returns null if there is no transaction.
3292          *
3293          * @return array|null ('lag': seconds or false on error, 'since': UNIX timestamp of BEGIN)
3294          * @since 1.27
3295          */
3296         protected function getTransactionLagStatus() {
3297                 return $this->trxLevel
3298                         ? [ 'lag' => $this->trxReplicaLag, 'since' => $this->trxTimestamp() ]
3299                         : null;
3300         }
3301
3302         /**
3303          * Get a replica DB lag estimate for this server
3304          *
3305          * @return array ('lag': seconds or false on error, 'since': UNIX timestamp of estimate)
3306          * @since 1.27
3307          */
3308         protected function getApproximateLagStatus() {
3309                 return [
3310                         'lag'   => $this->getLBInfo( 'replica' ) ? $this->getLag() : 0,
3311                         'since' => microtime( true )
3312                 ];
3313         }
3314
3315         /**
3316          * Merge the result of getSessionLagStatus() for several DBs
3317          * using the most pessimistic values to estimate the lag of
3318          * any data derived from them in combination
3319          *
3320          * This is information is useful for caching modules
3321          *
3322          * @see WANObjectCache::set()
3323          * @see WANObjectCache::getWithSetCallback()
3324          *
3325          * @param IDatabase $db1
3326          * @param IDatabase $db2 [optional]
3327          * @return array Map of values:
3328          *   - lag: highest lag of any of the DBs or false on error (e.g. replication stopped)
3329          *   - since: oldest UNIX timestamp of any of the DB lag estimates
3330          *   - pending: whether any of the DBs have uncommitted changes
3331          * @throws DBError
3332          * @since 1.27
3333          */
3334         public static function getCacheSetOptions( IDatabase $db1, IDatabase $db2 = null ) {
3335                 $res = [ 'lag' => 0, 'since' => INF, 'pending' => false ];
3336                 foreach ( func_get_args() as $db ) {
3337                         /** @var IDatabase $db */
3338                         $status = $db->getSessionLagStatus();
3339                         if ( $status['lag'] === false ) {
3340                                 $res['lag'] = false;
3341                         } elseif ( $res['lag'] !== false ) {
3342                                 $res['lag'] = max( $res['lag'], $status['lag'] );
3343                         }
3344                         $res['since'] = min( $res['since'], $status['since'] );
3345                         $res['pending'] = $res['pending'] ?: $db->writesPending();
3346                 }
3347
3348                 return $res;
3349         }
3350
3351         public function getLag() {
3352                 return 0;
3353         }
3354
3355         public function maxListLen() {
3356                 return 0;
3357         }
3358
3359         public function encodeBlob( $b ) {
3360                 return $b;
3361         }
3362
3363         public function decodeBlob( $b ) {
3364                 if ( $b instanceof Blob ) {
3365                         $b = $b->fetch();
3366                 }
3367                 return $b;
3368         }
3369
3370         public function setSessionOptions( array $options ) {
3371         }
3372
3373         public function sourceFile(
3374                 $filename,
3375                 callable $lineCallback = null,
3376                 callable $resultCallback = null,
3377                 $fname = false,
3378                 callable $inputCallback = null
3379         ) {
3380                 Wikimedia\suppressWarnings();
3381                 $fp = fopen( $filename, 'r' );
3382                 Wikimedia\restoreWarnings();
3383
3384                 if ( false === $fp ) {
3385                         throw new RuntimeException( "Could not open \"{$filename}\".\n" );
3386                 }
3387
3388                 if ( !$fname ) {
3389                         $fname = __METHOD__ . "( $filename )";
3390                 }
3391
3392                 try {
3393                         $error = $this->sourceStream(
3394                                 $fp, $lineCallback, $resultCallback, $fname, $inputCallback );
3395                 } catch ( Exception $e ) {
3396                         fclose( $fp );
3397                         throw $e;
3398                 }
3399
3400                 fclose( $fp );
3401
3402                 return $error;
3403         }
3404
3405         public function setSchemaVars( $vars ) {
3406                 $this->schemaVars = $vars;
3407         }
3408
3409         public function sourceStream(
3410                 $fp,
3411                 callable $lineCallback = null,
3412                 callable $resultCallback = null,
3413                 $fname = __METHOD__,
3414                 callable $inputCallback = null
3415         ) {
3416                 $delimiterReset = new ScopedCallback(
3417                         function ( $delimiter ) {
3418                                 $this->delimiter = $delimiter;
3419                         },
3420                         [ $this->delimiter ]
3421                 );
3422                 $cmd = '';
3423
3424                 while ( !feof( $fp ) ) {
3425                         if ( $lineCallback ) {
3426                                 call_user_func( $lineCallback );
3427                         }
3428
3429                         $line = trim( fgets( $fp ) );
3430
3431                         if ( $line == '' ) {
3432                                 continue;
3433                         }
3434
3435                         if ( '-' == $line[0] && '-' == $line[1] ) {
3436                                 continue;
3437                         }
3438
3439                         if ( $cmd != '' ) {
3440                                 $cmd .= ' ';
3441                         }
3442
3443                         $done = $this->streamStatementEnd( $cmd, $line );
3444
3445                         $cmd .= "$line\n";
3446
3447                         if ( $done || feof( $fp ) ) {
3448                                 $cmd = $this->replaceVars( $cmd );
3449
3450                                 if ( $inputCallback ) {
3451                                         $callbackResult = call_user_func( $inputCallback, $cmd );
3452
3453                                         if ( is_string( $callbackResult ) || !$callbackResult ) {
3454                                                 $cmd = $callbackResult;
3455                                         }
3456                                 }
3457
3458                                 if ( $cmd ) {
3459                                         $res = $this->query( $cmd, $fname );
3460
3461                                         if ( $resultCallback ) {
3462                                                 call_user_func( $resultCallback, $res, $this );
3463                                         }
3464
3465                                         if ( false === $res ) {
3466                                                 $err = $this->lastError();
3467
3468                                                 return "Query \"{$cmd}\" failed with error code \"$err\".\n";
3469                                         }
3470                                 }
3471                                 $cmd = '';
3472                         }
3473                 }
3474
3475                 ScopedCallback::consume( $delimiterReset );
3476                 return true;
3477         }
3478
3479         /**
3480          * Called by sourceStream() to check if we've reached a statement end
3481          *
3482          * @param string &$sql SQL assembled so far
3483          * @param string &$newLine New line about to be added to $sql
3484          * @return bool Whether $newLine contains end of the statement
3485          */
3486         public function streamStatementEnd( &$sql, &$newLine ) {
3487                 if ( $this->delimiter ) {
3488                         $prev = $newLine;
3489                         $newLine = preg_replace(
3490                                 '/' . preg_quote( $this->delimiter, '/' ) . '$/', '', $newLine );
3491                         if ( $newLine != $prev ) {
3492                                 return true;
3493                         }
3494                 }
3495
3496                 return false;
3497         }
3498
3499         /**
3500          * Database independent variable replacement. Replaces a set of variables
3501          * in an SQL statement with their contents as given by $this->getSchemaVars().
3502          *
3503          * Supports '{$var}' `{$var}` and / *$var* / (without the spaces) style variables.
3504          *
3505          * - '{$var}' should be used for text and is passed through the database's
3506          *   addQuotes method.
3507          * - `{$var}` should be used for identifiers (e.g. table and database names).
3508          *   It is passed through the database's addIdentifierQuotes method which
3509          *   can be overridden if the database uses something other than backticks.
3510          * - / *_* / or / *$wgDBprefix* / passes the name that follows through the
3511          *   database's tableName method.
3512          * - / *i* / passes the name that follows through the database's indexName method.
3513          * - In all other cases, / *$var* / is left unencoded. Except for table options,
3514          *   its use should be avoided. In 1.24 and older, string encoding was applied.
3515          *
3516          * @param string $ins SQL statement to replace variables in
3517          * @return string The new SQL statement with variables replaced
3518          */
3519         protected function replaceVars( $ins ) {
3520                 $vars = $this->getSchemaVars();
3521                 return preg_replace_callback(
3522                         '!
3523                                 /\* (\$wgDBprefix|[_i]) \*/ (\w*) | # 1-2. tableName, indexName
3524                                 \'\{\$ (\w+) }\'                  | # 3. addQuotes
3525                                 `\{\$ (\w+) }`                    | # 4. addIdentifierQuotes
3526                                 /\*\$ (\w+) \*/                     # 5. leave unencoded
3527                         !x',
3528                         function ( $m ) use ( $vars ) {
3529                                 // Note: Because of <https://bugs.php.net/bug.php?id=51881>,
3530                                 // check for both nonexistent keys *and* the empty string.
3531                                 if ( isset( $m[1] ) && $m[1] !== '' ) {
3532                                         if ( $m[1] === 'i' ) {
3533                                                 return $this->indexName( $m[2] );
3534                                         } else {
3535                                                 return $this->tableName( $m[2] );
3536                                         }
3537                                 } elseif ( isset( $m[3] ) && $m[3] !== '' && array_key_exists( $m[3], $vars ) ) {
3538                                         return $this->addQuotes( $vars[$m[3]] );
3539                                 } elseif ( isset( $m[4] ) && $m[4] !== '' && array_key_exists( $m[4], $vars ) ) {
3540                                         return $this->addIdentifierQuotes( $vars[$m[4]] );
3541                                 } elseif ( isset( $m[5] ) && $m[5] !== '' && array_key_exists( $m[5], $vars ) ) {
3542                                         return $vars[$m[5]];
3543                                 } else {
3544                                         return $m[0];
3545                                 }
3546                         },
3547                         $ins
3548                 );
3549         }
3550
3551         /**
3552          * Get schema variables. If none have been set via setSchemaVars(), then
3553          * use some defaults from the current object.
3554          *
3555          * @return array
3556          */
3557         protected function getSchemaVars() {
3558                 if ( $this->schemaVars ) {
3559                         return $this->schemaVars;
3560                 } else {
3561                         return $this->getDefaultSchemaVars();
3562                 }
3563         }
3564
3565         /**
3566          * Get schema variables to use if none have been set via setSchemaVars().
3567          *
3568          * Override this in derived classes to provide variables for tables.sql
3569          * and SQL patch files.
3570          *
3571          * @return array
3572          */
3573         protected function getDefaultSchemaVars() {
3574                 return [];
3575         }
3576
3577         public function lockIsFree( $lockName, $method ) {
3578                 // RDBMs methods for checking named locks may or may not count this thread itself.
3579                 // In MySQL, IS_FREE_LOCK() returns 0 if the thread already has the lock. This is
3580                 // the behavior choosen by the interface for this method.
3581                 return !isset( $this->namedLocksHeld[$lockName] );
3582         }
3583
3584         public function lock( $lockName, $method, $timeout = 5 ) {
3585                 $this->namedLocksHeld[$lockName] = 1;
3586
3587                 return true;
3588         }
3589
3590         public function unlock( $lockName, $method ) {
3591                 unset( $this->namedLocksHeld[$lockName] );
3592
3593                 return true;
3594         }
3595
3596         public function getScopedLockAndFlush( $lockKey, $fname, $timeout ) {
3597                 if ( $this->writesOrCallbacksPending() ) {
3598                         // This only flushes transactions to clear snapshots, not to write data
3599                         $fnames = implode( ', ', $this->pendingWriteAndCallbackCallers() );
3600                         throw new DBUnexpectedError(
3601                                 $this,
3602                                 "$fname: Cannot flush pre-lock snapshot because writes are pending ($fnames)."
3603                         );
3604                 }
3605
3606                 if ( !$this->lock( $lockKey, $fname, $timeout ) ) {
3607                         return null;
3608                 }
3609
3610                 $unlocker = new ScopedCallback( function () use ( $lockKey, $fname ) {
3611                         if ( $this->trxLevel() ) {
3612                                 // There is a good chance an exception was thrown, causing any early return
3613                                 // from the caller. Let any error handler get a chance to issue rollback().
3614                                 // If there isn't one, let the error bubble up and trigger server-side rollback.
3615                                 $this->onTransactionResolution(
3616                                         function () use ( $lockKey, $fname ) {
3617                                                 $this->unlock( $lockKey, $fname );
3618                                         },
3619                                         $fname
3620                                 );
3621                         } else {
3622                                 $this->unlock( $lockKey, $fname );
3623                         }
3624                 } );
3625
3626                 $this->commit( $fname, self::FLUSHING_INTERNAL );
3627
3628                 return $unlocker;
3629         }
3630
3631         public function namedLocksEnqueue() {
3632                 return false;
3633         }
3634
3635         public function tableLocksHaveTransactionScope() {
3636                 return true;
3637         }
3638
3639         final public function lockTables( array $read, array $write, $method ) {
3640                 if ( $this->writesOrCallbacksPending() ) {
3641                         throw new DBUnexpectedError( $this, "Transaction writes or callbacks still pending." );
3642                 }
3643
3644                 if ( $this->tableLocksHaveTransactionScope() ) {
3645                         $this->startAtomic( $method );
3646                 }
3647
3648                 return $this->doLockTables( $read, $write, $method );
3649         }
3650
3651         /**
3652          * Helper function for lockTables() that handles the actual table locking
3653          *
3654          * @param array $read Array of tables to lock for read access
3655          * @param array $write Array of tables to lock for write access
3656          * @param string $method Name of caller
3657          * @return true
3658          */
3659         protected function doLockTables( array $read, array $write, $method ) {
3660                 return true;
3661         }
3662
3663         final public function unlockTables( $method ) {
3664                 if ( $this->tableLocksHaveTransactionScope() ) {
3665                         $this->endAtomic( $method );
3666
3667                         return true; // locks released on COMMIT/ROLLBACK
3668                 }
3669
3670                 return $this->doUnlockTables( $method );
3671         }
3672
3673         /**
3674          * Helper function for unlockTables() that handles the actual table unlocking
3675          *
3676          * @param string $method Name of caller
3677          * @return true
3678          */
3679         protected function doUnlockTables( $method ) {
3680                 return true;
3681         }
3682
3683         /**
3684          * Delete a table
3685          * @param string $tableName
3686          * @param string $fName
3687          * @return bool|ResultWrapper
3688          * @since 1.18
3689          */
3690         public function dropTable( $tableName, $fName = __METHOD__ ) {
3691                 if ( !$this->tableExists( $tableName, $fName ) ) {
3692                         return false;
3693                 }
3694                 $sql = "DROP TABLE " . $this->tableName( $tableName ) . " CASCADE";
3695
3696                 return $this->query( $sql, $fName );
3697         }
3698
3699         public function getInfinity() {
3700                 return 'infinity';
3701         }
3702
3703         public function encodeExpiry( $expiry ) {
3704                 return ( $expiry == '' || $expiry == 'infinity' || $expiry == $this->getInfinity() )
3705                         ? $this->getInfinity()
3706                         : $this->timestamp( $expiry );
3707         }
3708
3709         public function decodeExpiry( $expiry, $format = TS_MW ) {
3710                 if ( $expiry == '' || $expiry == 'infinity' || $expiry == $this->getInfinity() ) {
3711                         return 'infinity';
3712                 }
3713
3714                 return ConvertibleTimestamp::convert( $format, $expiry );
3715         }
3716
3717         public function setBigSelects( $value = true ) {
3718                 // no-op
3719         }
3720
3721         public function isReadOnly() {
3722                 return ( $this->getReadOnlyReason() !== false );
3723         }
3724
3725         /**
3726          * @return string|bool Reason this DB is read-only or false if it is not
3727          */
3728         protected function getReadOnlyReason() {
3729                 $reason = $this->getLBInfo( 'readOnlyReason' );
3730
3731                 return is_string( $reason ) ? $reason : false;
3732         }
3733
3734         public function setTableAliases( array $aliases ) {
3735                 $this->tableAliases = $aliases;
3736         }
3737
3738         /**
3739          * @return bool Whether a DB user is required to access the DB
3740          * @since 1.28
3741          */
3742         protected function requiresDatabaseUser() {
3743                 return true;
3744         }
3745
3746         /**
3747          * Get the underlying binding connection handle
3748          *
3749          * Makes sure the connection resource is set (disconnects and ping() failure can unset it).
3750          * This catches broken callers than catch and ignore disconnection exceptions.
3751          * Unlike checking isOpen(), this is safe to call inside of open().
3752          *
3753          * @return resource|object
3754          * @throws DBUnexpectedError
3755          * @since 1.26
3756          */
3757         protected function getBindingHandle() {
3758                 if ( !$this->conn ) {
3759                         throw new DBUnexpectedError(
3760                                 $this,
3761                                 'DB connection was already closed or the connection dropped.'
3762                         );
3763                 }
3764
3765                 return $this->conn;
3766         }
3767
3768         /**
3769          * @since 1.19
3770          * @return string
3771          */
3772         public function __toString() {
3773                 return (string)$this->conn;
3774         }
3775
3776         /**
3777          * Make sure that copies do not share the same client binding handle
3778          * @throws DBConnectionError
3779          */
3780         public function __clone() {
3781                 $this->connLogger->warning(
3782                         "Cloning " . static::class . " is not recomended; forking connection:\n" .
3783                         ( new RuntimeException() )->getTraceAsString()
3784                 );
3785
3786                 if ( $this->isOpen() ) {
3787                         // Open a new connection resource without messing with the old one
3788                         $this->opened = false;
3789                         $this->conn = false;
3790                         $this->trxEndCallbacks = []; // don't copy
3791                         $this->handleSessionLoss(); // no trx or locks anymore
3792                         $this->open( $this->server, $this->user, $this->password, $this->dbName );
3793                         $this->lastPing = microtime( true );
3794                 }
3795         }
3796
3797         /**
3798          * Called by serialize. Throw an exception when DB connection is serialized.
3799          * This causes problems on some database engines because the connection is
3800          * not restored on unserialize.
3801          */
3802         public function __sleep() {
3803                 throw new RuntimeException( 'Database serialization may cause problems, since ' .
3804                         'the connection is not restored on wakeup.' );
3805         }
3806
3807         /**
3808          * Run a few simple sanity checks and close dangling connections
3809          */
3810         public function __destruct() {
3811                 if ( $this->trxLevel && $this->trxDoneWrites ) {
3812                         trigger_error( "Uncommitted DB writes (transaction from {$this->trxFname})." );
3813                 }
3814
3815                 $danglingWriters = $this->pendingWriteAndCallbackCallers();
3816                 if ( $danglingWriters ) {
3817                         $fnames = implode( ', ', $danglingWriters );
3818                         trigger_error( "DB transaction writes or callbacks still pending ($fnames)." );
3819                 }
3820
3821                 if ( $this->conn ) {
3822                         // Avoid connection leaks for sanity. Normally, resources close at script completion.
3823                         // The connection might already be closed in zend/hhvm by now, so suppress warnings.
3824                         Wikimedia\suppressWarnings();
3825                         $this->closeConnection();
3826                         Wikimedia\restoreWarnings();
3827                         $this->conn = false;
3828                         $this->opened = false;
3829                 }
3830         }
3831 }
3832
3833 class_alias( Database::class, 'DatabaseBase' ); // b/c for old name
3834 class_alias( Database::class, 'Database' ); // b/c global alias