includes/db/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 use Psr\Log\LoggerAwareInterface;
  27 use Psr\Log\LoggerInterface;
  28
  29 /**
  30  * Database abstraction object
  31  * @ingroup Database
  32  */
  33 abstract class DatabaseBase implements IDatabase, LoggerAwareInterface {
  34         /** Number of times to re-try an operation in case of deadlock */
  35         const DEADLOCK_TRIES = 4;
  36         /** Minimum time to wait before retry, in microseconds */
  37         const DEADLOCK_DELAY_MIN = 500000;
  38         /** Maximum time to wait before retry */
  39         const DEADLOCK_DELAY_MAX = 1500000;
  40
  41         /** How long before it is worth doing a dummy query to test the connection */
  42         const PING_TTL = 1.0;
  43         const PING_QUERY = 'SELECT 1 AS ping';
  44
  45         const TINY_WRITE_SEC = .010;
  46         const SLOW_WRITE_SEC = .500;
  47         const SMALL_WRITE_ROWS = 100;
  48
  49         /** @var string SQL query */
  50         protected $mLastQuery = '';
  51         /** @var bool */
  52         protected $mDoneWrites = false;
  53         /** @var string|bool */
  54         protected $mPHPError = false;
  55         /** @var string */
  56         protected $mServer;
  57         /** @var string */
  58         protected $mUser;
  59         /** @var string */
  60         protected $mPassword;
  61         /** @var string */
  62         protected $mDBname;
  63         /** @var bool */
  64         protected $cliMode;
  65
  66         /** @var BagOStuff APC cache */
  67         protected $srvCache;
  68         /** @var LoggerInterface */
  69         protected $connLogger;
  70         /** @var LoggerInterface */
  71         protected $queryLogger;
  72
  73         /** @var resource Database connection */
  74         protected $mConn = null;
  75         /** @var bool */
  76         protected $mOpened = false;
  77
  78         /** @var array[] List of (callable, method name) */
  79         protected $mTrxIdleCallbacks = [];
  80         /** @var array[] List of (callable, method name) */
  81         protected $mTrxPreCommitCallbacks = [];
  82         /** @var array[] List of (callable, method name) */
  83         protected $mTrxEndCallbacks = [];
  84         /** @var array[] Map of (name => (callable, method name)) */
  85         protected $mTrxRecurringCallbacks = [];
  86         /** @var bool Whether to suppress triggering of transaction end callbacks */
  87         protected $mTrxEndCallbacksSuppressed = false;
  88
  89         /** @var string */
  90         protected $mTablePrefix;
  91         /** @var string */
  92         protected $mSchema;
  93         /** @var integer */
  94         protected $mFlags;
  95         /** @var bool */
  96         protected $mForeign;
  97         /** @var array */
  98         protected $mLBInfo = [];
  99         /** @var bool|null */
 100         protected $mDefaultBigSelects = null;
 101         /** @var array|bool */
 102         protected $mSchemaVars = false;
 103         /** @var array */
 104         protected $mSessionVars = [];
 105         /** @var array|null */
 106         protected $preparedArgs;
 107         /** @var string|bool|null Stashed value of html_errors INI setting */
 108         protected $htmlErrors;
 109         /** @var string */
 110         protected $delimiter = ';';
 111
 112         /**
 113          * Either 1 if a transaction is active or 0 otherwise.
 114          * The other Trx fields may not be meaningfull if this is 0.
 115          *
 116          * @var int
 117          */
 118         protected $mTrxLevel = 0;
 119         /**
 120          * Either a short hexidecimal string if a transaction is active or ""
 121          *
 122          * @var string
 123          * @see DatabaseBase::mTrxLevel
 124          */
 125         protected $mTrxShortId = '';
 126         /**
 127          * The UNIX time that the transaction started. Callers can assume that if
 128          * snapshot isolation is used, then the data is *at least* up to date to that
 129          * point (possibly more up-to-date since the first SELECT defines the snapshot).
 130          *
 131          * @var float|null
 132          * @see DatabaseBase::mTrxLevel
 133          */
 134         private $mTrxTimestamp = null;
 135         /** @var float Lag estimate at the time of BEGIN */
 136         private $mTrxReplicaLag = null;
 137         /**
 138          * Remembers the function name given for starting the most recent transaction via begin().
 139          * Used to provide additional context for error reporting.
 140          *
 141          * @var string
 142          * @see DatabaseBase::mTrxLevel
 143          */
 144         private $mTrxFname = null;
 145         /**
 146          * Record if possible write queries were done in the last transaction started
 147          *
 148          * @var bool
 149          * @see DatabaseBase::mTrxLevel
 150          */
 151         private $mTrxDoneWrites = false;
 152         /**
 153          * Record if the current transaction was started implicitly due to DBO_TRX being set.
 154          *
 155          * @var bool
 156          * @see DatabaseBase::mTrxLevel
 157          */
 158         private $mTrxAutomatic = false;
 159         /**
 160          * Array of levels of atomicity within transactions
 161          *
 162          * @var array
 163          */
 164         private $mTrxAtomicLevels = [];
 165         /**
 166          * Record if the current transaction was started implicitly by DatabaseBase::startAtomic
 167          *
 168          * @var bool
 169          */
 170         private $mTrxAutomaticAtomic = false;
 171         /**
 172          * Track the write query callers of the current transaction
 173          *
 174          * @var string[]
 175          */
 176         private $mTrxWriteCallers = [];
 177         /**
 178          * @var float Seconds spent in write queries for the current transaction
 179          */
 180         private $mTrxWriteDuration = 0.0;
 181         /**
 182          * @var integer Number of write queries for the current transaction
 183          */
 184         private $mTrxWriteQueryCount = 0;
 185         /**
 186          * @var float Like mTrxWriteQueryCount but excludes lock-bound, easy to replicate, queries
 187          */
 188         private $mTrxWriteAdjDuration = 0.0;
 189         /**
 190          * @var integer Number of write queries counted in mTrxWriteAdjDuration
 191          */
 192         private $mTrxWriteAdjQueryCount = 0;
 193         /**
 194          * @var float RTT time estimate
 195          */
 196         private $mRTTEstimate = 0.0;
 197
 198         /** @var array Map of (name => 1) for locks obtained via lock() */
 199         private $mNamedLocksHeld = [];
 200
 201         /** @var IDatabase|null Lazy handle to the master DB this server replicates from */
 202         private $lazyMasterHandle;
 203
 204         /**
 205          * @since 1.21
 206          * @var resource File handle for upgrade
 207          */
 208         protected $fileHandle = null;
 209
 210         /**
 211          * @since 1.22
 212          * @var string[] Process cache of VIEWs names in the database
 213          */
 214         protected $allViews = null;
 215
 216         /** @var float UNIX timestamp */
 217         protected $lastPing = 0.0;
 218
 219         /** @var int[] Prior mFlags values */
 220         private $priorFlags = [];
 221
 222         /** @var Profiler */
 223         protected $profiler;
 224         /** @var TransactionProfiler */
 225         protected $trxProfiler;
 226
 227         /**
 228          * Constructor.
 229          *
 230          * FIXME: It is possible to construct a Database object with no associated
 231          * connection object, by specifying no parameters to __construct(). This
 232          * feature is deprecated and should be removed.
 233          *
 234          * DatabaseBase subclasses should not be constructed directly in external
 235          * code. DatabaseBase::factory() should be used instead.
 236          *
 237          * @param array $params Parameters passed from DatabaseBase::factory()
 238          */
 239         function __construct( array $params ) {
 240                 global $wgDBprefix, $wgDBmwschema;
 241
 242                 $this->srvCache = ObjectCache::getLocalServerInstance( 'hash' );
 243
 244                 $server = $params['host'];
 245                 $user = $params['user'];
 246                 $password = $params['password'];
 247                 $dbName = $params['dbname'];
 248                 $flags = $params['flags'];
 249                 $tablePrefix = $params['tablePrefix'];
 250                 $schema = $params['schema'];
 251                 $foreign = $params['foreign'];
 252
 253                 $this->cliMode = isset( $params['cliMode'] )
 254                         ? $params['cliMode']
 255                         : ( PHP_SAPI === 'cli' );
 256
 257                 $this->mFlags = $flags;
 258                 if ( $this->mFlags & DBO_DEFAULT ) {
 259                         if ( $this->cliMode ) {
 260                                 $this->mFlags &= ~DBO_TRX;
 261                         } else {
 262                                 $this->mFlags |= DBO_TRX;
 263                         }
 264                 }
 265
 266                 $this->mSessionVars = $params['variables'];
 267
 268                 /** Get the default table prefix*/
 269                 if ( $tablePrefix === 'get from global' ) {
 270                         $this->mTablePrefix = $wgDBprefix;
 271                 } else {
 272                         $this->mTablePrefix = $tablePrefix;
 273                 }
 274
 275                 /** Get the database schema*/
 276                 if ( $schema === 'get from global' ) {
 277                         $this->mSchema = $wgDBmwschema;
 278                 } else {
 279                         $this->mSchema = $schema;
 280                 }
 281
 282                 $this->mForeign = $foreign;
 283
 284                 $this->profiler = isset( $params['profiler'] )
 285                         ? $params['profiler']
 286                         : Profiler::instance(); // @TODO: remove global state
 287                 $this->trxProfiler = isset( $params['trxProfiler'] )
 288                         ? $params['trxProfiler']
 289                         : new TransactionProfiler();
 290                 $this->connLogger = isset( $params['connLogger'] )
 291                         ? $params['connLogger']
 292                         : new \Psr\Log\NullLogger();
 293                 $this->queryLogger = isset( $params['queryLogger'] )
 294                         ? $params['queryLogger']
 295                         : new \Psr\Log\NullLogger();
 296
 297                 if ( $user ) {
 298                         $this->open( $server, $user, $password, $dbName );
 299                 }
 300         }
 301
 302         /**
 303          * Given a DB type, construct the name of the appropriate child class of
 304          * DatabaseBase. This is designed to replace all of the manual stuff like:
 305          *    $class = 'Database' . ucfirst( strtolower( $dbType ) );
 306          * as well as validate against the canonical list of DB types we have
 307          *
 308          * This factory function is mostly useful for when you need to connect to a
 309          * database other than the MediaWiki default (such as for external auth,
 310          * an extension, et cetera). Do not use this to connect to the MediaWiki
 311          * database. Example uses in core:
 312          * @see LoadBalancer::reallyOpenConnection()
 313          * @see ForeignDBRepo::getMasterDB()
 314          * @see WebInstallerDBConnect::execute()
 315          *
 316          * @since 1.18
 317          *
 318          * @param string $dbType A possible DB type
 319          * @param array $p An array of options to pass to the constructor.
 320          *    Valid options are: host, user, password, dbname, flags, tablePrefix, schema, driver
 321          * @throws MWException If the database driver or extension cannot be found
 322          * @return DatabaseBase|null DatabaseBase subclass or null
 323          */
 324         final public static function factory( $dbType, $p = [] ) {
 325                 global $wgCommandLineMode;
 326
 327                 $canonicalDBTypes = [
 328                         'mysql' => [ 'mysqli', 'mysql' ],
 329                         'postgres' => [],
 330                         'sqlite' => [],
 331                         'oracle' => [],
 332                         'mssql' => [],
 333                 ];
 334
 335                 $driver = false;
 336                 $dbType = strtolower( $dbType );
 337                 if ( isset( $canonicalDBTypes[$dbType] ) && $canonicalDBTypes[$dbType] ) {
 338                         $possibleDrivers = $canonicalDBTypes[$dbType];
 339                         if ( !empty( $p['driver'] ) ) {
 340                                 if ( in_array( $p['driver'], $possibleDrivers ) ) {
 341                                         $driver = $p['driver'];
 342                                 } else {
 343                                         throw new MWException( __METHOD__ .
 344                                                 " cannot construct Database with type '$dbType' and driver '{$p['driver']}'" );
 345                                 }
 346                         } else {
 347                                 foreach ( $possibleDrivers as $posDriver ) {
 348                                         if ( extension_loaded( $posDriver ) ) {
 349                                                 $driver = $posDriver;
 350                                                 break;
 351                                         }
 352                                 }
 353                         }
 354                 } else {
 355                         $driver = $dbType;
 356                 }
 357                 if ( $driver === false ) {
 358                         throw new MWException( __METHOD__ .
 359                                 " no viable database extension found for type '$dbType'" );
 360                 }
 361
 362                 // Determine schema defaults. Currently Microsoft SQL Server uses $wgDBmwschema,
 363                 // and everything else doesn't use a schema (e.g. null)
 364                 // Although postgres and oracle support schemas, we don't use them (yet)
 365                 // to maintain backwards compatibility
 366                 $defaultSchemas = [
 367                         'mssql' => 'get from global',
 368                 ];
 369
 370                 $class = 'Database' . ucfirst( $driver );
 371                 if ( class_exists( $class ) && is_subclass_of( $class, 'DatabaseBase' ) ) {
 372                         // Resolve some defaults for b/c
 373                         $p['host'] = isset( $p['host'] ) ? $p['host'] : false;
 374                         $p['user'] = isset( $p['user'] ) ? $p['user'] : false;
 375                         $p['password'] = isset( $p['password'] ) ? $p['password'] : false;
 376                         $p['dbname'] = isset( $p['dbname'] ) ? $p['dbname'] : false;
 377                         $p['flags'] = isset( $p['flags'] ) ? $p['flags'] : 0;
 378                         $p['variables'] = isset( $p['variables'] ) ? $p['variables'] : [];
 379                         $p['tablePrefix'] = isset( $p['tablePrefix'] ) ? $p['tablePrefix'] : 'get from global';
 380                         if ( !isset( $p['schema'] ) ) {
 381                                 $p['schema'] = isset( $defaultSchemas[$dbType] ) ? $defaultSchemas[$dbType] : null;
 382                         }
 383                         $p['foreign'] = isset( $p['foreign'] ) ? $p['foreign'] : false;
 384                         $p['cliMode'] = $wgCommandLineMode;
 385
 386                         $conn = new $class( $p );
 387                         if ( isset( $p['connLogger'] ) ) {
 388                                 $conn->connLogger = $p['connLogger'];
 389                         }
 390                         if ( isset( $p['queryLogger'] ) ) {
 391                                 $conn->queryLogger = $p['queryLogger'];
 392                         }
 393                 } else {
 394                         $conn = null;
 395                 }
 396
 397                 return $conn;
 398         }
 399
 400         public function setLogger( LoggerInterface $logger ) {
 401                 $this->quertLogger = $logger;
 402         }
 403
 404         public function getServerInfo() {
 405                 return $this->getServerVersion();
 406         }
 407
 408         /**
 409          * @return string Command delimiter used by this database engine
 410          */
 411         public function getDelimiter() {
 412                 return $this->delimiter;
 413         }
 414
 415         /**
 416          * Boolean, controls output of large amounts of debug information.
 417          * @param bool|null $debug
 418          *   - true to enable debugging
 419          *   - false to disable debugging
 420          *   - omitted or null to do nothing
 421          *
 422          * @return bool|null Previous value of the flag
 423          */
 424         public function debug( $debug = null ) {
 425                 return wfSetBit( $this->mFlags, DBO_DEBUG, $debug );
 426         }
 427
 428         public function bufferResults( $buffer = null ) {
 429                 if ( is_null( $buffer ) ) {
 430                         return !(bool)( $this->mFlags & DBO_NOBUFFER );
 431                 } else {
 432                         return !wfSetBit( $this->mFlags, DBO_NOBUFFER, !$buffer );
 433                 }
 434         }
 435
 436         /**
 437          * Turns on (false) or off (true) the automatic generation and sending
 438          * of a "we're sorry, but there has been a database error" page on
 439          * database errors. Default is on (false). When turned off, the
 440          * code should use lastErrno() and lastError() to handle the
 441          * situation as appropriate.
 442          *
 443          * Do not use this function outside of the Database classes.
 444          *
 445          * @param null|bool $ignoreErrors
 446          * @return bool The previous value of the flag.
 447          */
 448         protected function ignoreErrors( $ignoreErrors = null ) {
 449                 return wfSetBit( $this->mFlags, DBO_IGNORE, $ignoreErrors );
 450         }
 451
 452         public function trxLevel() {
 453                 return $this->mTrxLevel;
 454         }
 455
 456         public function trxTimestamp() {
 457                 return $this->mTrxLevel ? $this->mTrxTimestamp : null;
 458         }
 459
 460         public function tablePrefix( $prefix = null ) {
 461                 return wfSetVar( $this->mTablePrefix, $prefix );
 462         }
 463
 464         public function dbSchema( $schema = null ) {
 465                 return wfSetVar( $this->mSchema, $schema );
 466         }
 467
 468         /**
 469          * Set the filehandle to copy write statements to.
 470          *
 471          * @param resource $fh File handle
 472          */
 473         public function setFileHandle( $fh ) {
 474                 $this->fileHandle = $fh;
 475         }
 476
 477         public function getLBInfo( $name = null ) {
 478                 if ( is_null( $name ) ) {
 479                         return $this->mLBInfo;
 480                 } else {
 481                         if ( array_key_exists( $name, $this->mLBInfo ) ) {
 482                                 return $this->mLBInfo[$name];
 483                         } else {
 484                                 return null;
 485                         }
 486                 }
 487         }
 488
 489         public function setLBInfo( $name, $value = null ) {
 490                 if ( is_null( $value ) ) {
 491                         $this->mLBInfo = $name;
 492                 } else {
 493                         $this->mLBInfo[$name] = $value;
 494                 }
 495         }
 496
 497         /**
 498          * Set a lazy-connecting DB handle to the master DB (for replication status purposes)
 499          *
 500          * @param IDatabase $conn
 501          * @since 1.27
 502          */
 503         public function setLazyMasterHandle( IDatabase $conn ) {
 504                 $this->lazyMasterHandle = $conn;
 505         }
 506
 507         /**
 508          * @return IDatabase|null
 509          * @see setLazyMasterHandle()
 510          * @since 1.27
 511          */
 512         public function getLazyMasterHandle() {
 513                 return $this->lazyMasterHandle;
 514         }
 515
 516         /**
 517          * @param TransactionProfiler $profiler
 518          * @since 1.27
 519          */
 520         public function setTransactionProfiler( TransactionProfiler $profiler ) {
 521                 $this->trxProfiler = $profiler;
 522         }
 523
 524         /**
 525          * Returns true if this database supports (and uses) cascading deletes
 526          *
 527          * @return bool
 528          */
 529         public function cascadingDeletes() {
 530                 return false;
 531         }
 532
 533         /**
 534          * Returns true if this database supports (and uses) triggers (e.g. on the page table)
 535          *
 536          * @return bool
 537          */
 538         public function cleanupTriggers() {
 539                 return false;
 540         }
 541
 542         /**
 543          * Returns true if this database is strict about what can be put into an IP field.
 544          * Specifically, it uses a NULL value instead of an empty string.
 545          *
 546          * @return bool
 547          */
 548         public function strictIPs() {
 549                 return false;
 550         }
 551
 552         /**
 553          * Returns true if this database uses timestamps rather than integers
 554          *
 555          * @return bool
 556          */
 557         public function realTimestamps() {
 558                 return false;
 559         }
 560
 561         public function implicitGroupby() {
 562                 return true;
 563         }
 564
 565         public function implicitOrderby() {
 566                 return true;
 567         }
 568
 569         /**
 570          * Returns true if this database can do a native search on IP columns
 571          * e.g. this works as expected: .. WHERE rc_ip = '127.42.12.102/32';
 572          *
 573          * @return bool
 574          */
 575         public function searchableIPs() {
 576                 return false;
 577         }
 578
 579         /**
 580          * Returns true if this database can use functional indexes
 581          *
 582          * @return bool
 583          */
 584         public function functionalIndexes() {
 585                 return false;
 586         }
 587
 588         public function lastQuery() {
 589                 return $this->mLastQuery;
 590         }
 591
 592         public function doneWrites() {
 593                 return (bool)$this->mDoneWrites;
 594         }
 595
 596         public function lastDoneWrites() {
 597                 return $this->mDoneWrites ?: false;
 598         }
 599
 600         public function writesPending() {
 601                 return $this->mTrxLevel && $this->mTrxDoneWrites;
 602         }
 603
 604         public function writesOrCallbacksPending() {
 605                 return $this->mTrxLevel && (
 606                         $this->mTrxDoneWrites || $this->mTrxIdleCallbacks || $this->mTrxPreCommitCallbacks
 607                 );
 608         }
 609
 610         public function pendingWriteQueryDuration( $type = self::ESTIMATE_TOTAL ) {
 611                 if ( !$this->mTrxLevel ) {
 612                         return false;
 613                 } elseif ( !$this->mTrxDoneWrites ) {
 614                         return 0.0;
 615                 }
 616
 617                 switch ( $type ) {
 618                         case self::ESTIMATE_DB_APPLY:
 619                                 $this->ping( $rtt );
 620                                 $rttAdjTotal = $this->mTrxWriteAdjQueryCount * $rtt;
 621                                 $applyTime = max( $this->mTrxWriteAdjDuration - $rttAdjTotal, 0 );
 622                                 // For omitted queries, make them count as something at least
 623                                 $omitted = $this->mTrxWriteQueryCount - $this->mTrxWriteAdjQueryCount;
 624                                 $applyTime += self::TINY_WRITE_SEC * $omitted;
 625
 626                                 return $applyTime;
 627                         default: // everything
 628                                 return $this->mTrxWriteDuration;
 629                 }
 630         }
 631
 632         public function pendingWriteCallers() {
 633                 return $this->mTrxLevel ? $this->mTrxWriteCallers : [];
 634         }
 635
 636         public function isOpen() {
 637                 return $this->mOpened;
 638         }
 639
 640         public function setFlag( $flag, $remember = self::REMEMBER_NOTHING ) {
 641                 if ( $remember === self::REMEMBER_PRIOR ) {
 642                         array_push( $this->priorFlags, $this->mFlags );
 643                 }
 644                 $this->mFlags |= $flag;
 645         }
 646
 647         public function clearFlag( $flag, $remember = self::REMEMBER_NOTHING ) {
 648                 if ( $remember === self::REMEMBER_PRIOR ) {
 649                         array_push( $this->priorFlags, $this->mFlags );
 650                 }
 651                 $this->mFlags &= ~$flag;
 652         }
 653
 654         public function restoreFlags( $state = self::RESTORE_PRIOR ) {
 655                 if ( !$this->priorFlags ) {
 656                         return;
 657                 }
 658
 659                 if ( $state === self::RESTORE_INITIAL ) {
 660                         $this->mFlags = reset( $this->priorFlags );
 661                         $this->priorFlags = [];
 662                 } else {
 663                         $this->mFlags = array_pop( $this->priorFlags );
 664                 }
 665         }
 666
 667         public function getFlag( $flag ) {
 668                 return !!( $this->mFlags & $flag );
 669         }
 670
 671         public function getProperty( $name ) {
 672                 return $this->$name;
 673         }
 674
 675         public function getWikiID() {
 676                 if ( $this->mTablePrefix ) {
 677                         return "{$this->mDBname}-{$this->mTablePrefix}";
 678                 } else {
 679                         return $this->mDBname;
 680                 }
 681         }
 682
 683         /**
 684          * Return a path to the DBMS-specific SQL file if it exists,
 685          * otherwise default SQL file
 686          *
 687          * @param string $filename
 688          * @return string
 689          */
 690         private function getSqlFilePath( $filename ) {
 691                 global $IP;
 692                 $dbmsSpecificFilePath = "$IP/maintenance/" . $this->getType() . "/$filename";
 693                 if ( file_exists( $dbmsSpecificFilePath ) ) {
 694                         return $dbmsSpecificFilePath;
 695                 } else {
 696                         return "$IP/maintenance/$filename";
 697                 }
 698         }
 699
 700         /**
 701          * Return a path to the DBMS-specific schema file,
 702          * otherwise default to tables.sql
 703          *
 704          * @return string
 705          */
 706         public function getSchemaPath() {
 707                 return $this->getSqlFilePath( 'tables.sql' );
 708         }
 709
 710         /**
 711          * Return a path to the DBMS-specific update key file,
 712          * otherwise default to update-keys.sql
 713          *
 714          * @return string
 715          */
 716         public function getUpdateKeysPath() {
 717                 return $this->getSqlFilePath( 'update-keys.sql' );
 718         }
 719
 720         /**
 721          * Get information about an index into an object
 722          * @param string $table Table name
 723          * @param string $index Index name
 724          * @param string $fname Calling function name
 725          * @return mixed Database-specific index description class or false if the index does not exist
 726          */
 727         abstract function indexInfo( $table, $index, $fname = __METHOD__ );
 728
 729         /**
 730          * Wrapper for addslashes()
 731          *
 732          * @param string $s String to be slashed.
 733          * @return string Slashed string.
 734          */
 735         abstract function strencode( $s );
 736
 737         /**
 738          * Called by serialize. Throw an exception when DB connection is serialized.
 739          * This causes problems on some database engines because the connection is
 740          * not restored on unserialize.
 741          */
 742         public function __sleep() {
 743                 throw new MWException( 'Database serialization may cause problems, since ' .
 744                         'the connection is not restored on wakeup.' );
 745         }
 746
 747         protected function installErrorHandler() {
 748                 $this->mPHPError = false;
 749                 $this->htmlErrors = ini_set( 'html_errors', '0' );
 750                 set_error_handler( [ $this, 'connectionErrorHandler' ] );
 751         }
 752
 753         /**
 754          * @return bool|string
 755          */
 756         protected function restoreErrorHandler() {
 757                 restore_error_handler();
 758                 if ( $this->htmlErrors !== false ) {
 759                         ini_set( 'html_errors', $this->htmlErrors );
 760                 }
 761                 if ( $this->mPHPError ) {
 762                         $error = preg_replace( '!\[<a.*</a>\]!', '', $this->mPHPError );
 763                         $error = preg_replace( '!^.*?:\s?(.*)$!', '$1', $error );
 764
 765                         return $error;
 766                 } else {
 767                         return false;
 768                 }
 769         }
 770
 771         /**
 772          * @param int $errno
 773          * @param string $errstr
 774          */
 775         public function connectionErrorHandler( $errno, $errstr ) {
 776                 $this->mPHPError = $errstr;
 777         }
 778
 779         /**
 780          * Create a log context to pass to wfLogDBError or other logging functions.
 781          *
 782          * @param array $extras Additional data to add to context
 783          * @return array
 784          */
 785         protected function getLogContext( array $extras = [] ) {
 786                 return array_merge(
 787                         [
 788                                 'db_server' => $this->mServer,
 789                                 'db_name' => $this->mDBname,
 790                                 'db_user' => $this->mUser,
 791                         ],
 792                         $extras
 793                 );
 794         }
 795
 796         public function close() {
 797                 if ( $this->mConn ) {
 798                         if ( $this->trxLevel() ) {
 799                                 if ( !$this->mTrxAutomatic ) {
 800                                         wfWarn( "Transaction still in progress (from {$this->mTrxFname}), " .
 801                                                 " performing implicit commit before closing connection!" );
 802                                 }
 803
 804                                 $this->commit( __METHOD__, self::FLUSHING_INTERNAL );
 805                         }
 806
 807                         $closed = $this->closeConnection();
 808                         $this->mConn = false;
 809                 } elseif ( $this->mTrxIdleCallbacks || $this->mTrxEndCallbacks ) { // sanity
 810                         throw new MWException( "Transaction callbacks still pending." );
 811                 } else {
 812                         $closed = true;
 813                 }
 814                 $this->mOpened = false;
 815
 816                 return $closed;
 817         }
 818
 819         /**
 820          * Make sure isOpen() returns true as a sanity check
 821          *
 822          * @throws DBUnexpectedError
 823          */
 824         protected function assertOpen() {
 825                 if ( !$this->isOpen() ) {
 826                         throw new DBUnexpectedError( $this, "DB connection was already closed." );
 827                 }
 828         }
 829
 830         /**
 831          * Closes underlying database connection
 832          * @since 1.20
 833          * @return bool Whether connection was closed successfully
 834          */
 835         abstract protected function closeConnection();
 836
 837         function reportConnectionError( $error = 'Unknown error' ) {
 838                 $myError = $this->lastError();
 839                 if ( $myError ) {
 840                         $error = $myError;
 841                 }
 842
 843                 # New method
 844                 throw new DBConnectionError( $this, $error );
 845         }
 846
 847         /**
 848          * The DBMS-dependent part of query()
 849          *
 850          * @param string $sql SQL query.
 851          * @return ResultWrapper|bool Result object to feed to fetchObject,
 852          *   fetchRow, ...; or false on failure
 853          */
 854         abstract protected function doQuery( $sql );
 855
 856         /**
 857          * Determine whether a query writes to the DB.
 858          * Should return true if unsure.
 859          *
 860          * @param string $sql
 861          * @return bool
 862          */
 863         protected function isWriteQuery( $sql ) {
 864                 return !preg_match(
 865                         '/^(?:SELECT|BEGIN|ROLLBACK|COMMIT|SET|SHOW|EXPLAIN|\(SELECT)\b/i', $sql );
 866         }
 867
 868         /**
 869          * @param $sql
 870          * @return string|null
 871          */
 872         protected function getQueryVerb( $sql ) {
 873                 return preg_match( '/^\s*([a-z]+)/i', $sql, $m ) ? strtoupper( $m[1] ) : null;
 874         }
 875
 876         /**
 877          * Determine whether a SQL statement is sensitive to isolation level.
 878          * A SQL statement is considered transactable if its result could vary
 879          * depending on the transaction isolation level. Operational commands
 880          * such as 'SET' and 'SHOW' are not considered to be transactable.
 881          *
 882          * @param string $sql
 883          * @return bool
 884          */
 885         protected function isTransactableQuery( $sql ) {
 886                 $verb = $this->getQueryVerb( $sql );
 887                 return !in_array( $verb, [ 'BEGIN', 'COMMIT', 'ROLLBACK', 'SHOW', 'SET' ], true );
 888         }
 889
 890         public function query( $sql, $fname = __METHOD__, $tempIgnore = false ) {
 891                 global $wgUser;
 892
 893                 $priorWritesPending = $this->writesOrCallbacksPending();
 894                 $this->mLastQuery = $sql;
 895
 896                 $isWrite = $this->isWriteQuery( $sql );
 897                 if ( $isWrite ) {
 898                         $reason = $this->getReadOnlyReason();
 899                         if ( $reason !== false ) {
 900                                 throw new DBReadOnlyError( $this, "Database is read-only: $reason" );
 901                         }
 902                         # Set a flag indicating that writes have been done
 903                         $this->mDoneWrites = microtime( true );
 904                 }
 905
 906                 # Add a comment for easy SHOW PROCESSLIST interpretation
 907                 if ( is_object( $wgUser ) && $wgUser->isItemLoaded( 'name' ) ) {
 908                         $userName = $wgUser->getName();
 909                         if ( mb_strlen( $userName ) > 15 ) {
 910                                 $userName = mb_substr( $userName, 0, 15 ) . '...';
 911                         }
 912                         $userName = str_replace( '/', '', $userName );
 913                 } else {
 914                         $userName = '';
 915                 }
 916
 917                 // Add trace comment to the begin of the sql string, right after the operator.
 918                 // Or, for one-word queries (like "BEGIN" or COMMIT") add it to the end (bug 42598)
 919                 $commentedSql = preg_replace( '/\s|$/', " /* $fname $userName */ ", $sql, 1 );
 920
 921                 # Start implicit transactions that wrap the request if DBO_TRX is enabled
 922                 if ( !$this->mTrxLevel && $this->getFlag( DBO_TRX )
 923                         && $this->isTransactableQuery( $sql )
 924                 ) {
 925                         $this->begin( __METHOD__ . " ($fname)", self::TRANSACTION_INTERNAL );
 926                         $this->mTrxAutomatic = true;
 927                 }
 928
 929                 # Keep track of whether the transaction has write queries pending
 930                 if ( $this->mTrxLevel && !$this->mTrxDoneWrites && $isWrite ) {
 931                         $this->mTrxDoneWrites = true;
 932                         $this->trxProfiler->transactionWritingIn(
 933                                 $this->mServer, $this->mDBname, $this->mTrxShortId );
 934                 }
 935
 936                 if ( $this->debug() ) {
 937                         $this->queryLogger->debug( "{$this->mDBname} {$commentedSql}" );
 938                 }
 939
 940                 # Avoid fatals if close() was called
 941                 $this->assertOpen();
 942
 943                 # Send the query to the server
 944                 $ret = $this->doProfiledQuery( $sql, $commentedSql, $isWrite, $fname );
 945
 946                 # Try reconnecting if the connection was lost
 947                 if ( false === $ret && $this->wasErrorReissuable() ) {
 948                         $recoverable = $this->canRecoverFromDisconnect( $sql, $priorWritesPending );
 949                         # Stash the last error values before anything might clear them
 950                         $lastError = $this->lastError();
 951                         $lastErrno = $this->lastErrno();
 952                         # Update state tracking to reflect transaction loss due to disconnection
 953                         $this->handleTransactionLoss();
 954                         if ( $this->reconnect() ) {
 955                                 $msg = __METHOD__ . ": lost connection to {$this->getServer()}; reconnected";
 956                                 $this->connLogger->warning( $msg );
 957                                 $this->queryLogger->warning( "$msg:\n" . wfBacktrace( true ) );
 958
 959                                 if ( !$recoverable ) {
 960                                         # Callers may catch the exception and continue to use the DB
 961                                         $this->reportQueryError( $lastError, $lastErrno, $sql, $fname );
 962                                 } else {
 963                                         # Should be safe to silently retry the query
 964                                         $ret = $this->doProfiledQuery( $sql, $commentedSql, $isWrite, $fname );
 965                                 }
 966                         } else {
 967                                 $msg = __METHOD__ . ": lost connection to {$this->getServer()} permanently";
 968                                 $this->connLogger->error( $msg );
 969                         }
 970                 }
 971
 972                 if ( false === $ret ) {
 973                         # Deadlocks cause the entire transaction to abort, not just the statement.
 974                         # http://dev.mysql.com/doc/refman/5.7/en/innodb-error-handling.html
 975                         # https://www.postgresql.org/docs/9.1/static/explicit-locking.html
 976                         if ( $this->wasDeadlock() ) {
 977                                 if ( $this->explicitTrxActive() || $priorWritesPending ) {
 978                                         $tempIgnore = false; // not recoverable
 979                                 }
 980                                 # Update state tracking to reflect transaction loss
 981                                 $this->handleTransactionLoss();
 982                         }
 983
 984                         $this->reportQueryError(
 985                                 $this->lastError(), $this->lastErrno(), $sql, $fname, $tempIgnore );
 986                 }
 987
 988                 $res = $this->resultObject( $ret );
 989
 990                 return $res;
 991         }
 992
 993         private function doProfiledQuery( $sql, $commentedSql, $isWrite, $fname ) {
 994                 $isMaster = !is_null( $this->getLBInfo( 'master' ) );
 995                 # generalizeSQL() will probably cut down the query to reasonable
 996                 # logging size most of the time. The substr is really just a sanity check.
 997                 if ( $isMaster ) {
 998                         $queryProf = 'query-m: ' . substr( DatabaseBase::generalizeSQL( $sql ), 0, 255 );
 999                 } else {
1000                         $queryProf = 'query: ' . substr( DatabaseBase::generalizeSQL( $sql ), 0, 255 );
1001                 }
1002
1003                 # Include query transaction state
1004                 $queryProf .= $this->mTrxShortId ? " [TRX#{$this->mTrxShortId}]" : "";
1005
1006                 $startTime = microtime( true );
1007                 $this->profiler->profileIn( $queryProf );
1008                 $ret = $this->doQuery( $commentedSql );
1009                 $this->profiler->profileOut( $queryProf );
1010                 $queryRuntime = max( microtime( true ) - $startTime, 0.0 );
1011
1012                 unset( $queryProfSection ); // profile out (if set)
1013
1014                 if ( $ret !== false ) {
1015                         $this->lastPing = $startTime;
1016                         if ( $isWrite && $this->mTrxLevel ) {
1017                                 $this->updateTrxWriteQueryTime( $sql, $queryRuntime );
1018                                 $this->mTrxWriteCallers[] = $fname;
1019                         }
1020                 }
1021
1022                 if ( $sql === self::PING_QUERY ) {
1023                         $this->mRTTEstimate = $queryRuntime;
1024                 }
1025
1026                 $this->trxProfiler->recordQueryCompletion(
1027                         $queryProf, $startTime, $isWrite, $this->affectedRows()
1028                 );
1029                 MWDebug::query( $sql, $fname, $isMaster, $queryRuntime );
1030
1031                 return $ret;
1032         }
1033
1034         /**
1035          * Update the estimated run-time of a query, not counting large row lock times
1036          *
1037          * LoadBalancer can be set to rollback transactions that will create huge replication
1038          * lag. It bases this estimate off of pendingWriteQueryDuration(). Certain simple
1039          * queries, like inserting a row can take a long time due to row locking. This method
1040          * uses some simple heuristics to discount those cases.
1041          *
1042          * @param string $sql A SQL write query
1043          * @param float $runtime Total runtime, including RTT
1044          */
1045         private function updateTrxWriteQueryTime( $sql, $runtime ) {
1046                 // Whether this is indicative of replica DB runtime (except for RBR or ws_repl)
1047                 $indicativeOfReplicaRuntime = true;
1048                 if ( $runtime > self::SLOW_WRITE_SEC ) {
1049                         $verb = $this->getQueryVerb( $sql );
1050                         // insert(), upsert(), replace() are fast unless bulky in size or blocked on locks
1051                         if ( $verb === 'INSERT' ) {
1052                                 $indicativeOfReplicaRuntime = $this->affectedRows() > self::SMALL_WRITE_ROWS;
1053                         } elseif ( $verb === 'REPLACE' ) {
1054                                 $indicativeOfReplicaRuntime = $this->affectedRows() > self::SMALL_WRITE_ROWS / 2;
1055                         }
1056                 }
1057
1058                 $this->mTrxWriteDuration += $runtime;
1059                 $this->mTrxWriteQueryCount += 1;
1060                 if ( $indicativeOfReplicaRuntime ) {
1061                         $this->mTrxWriteAdjDuration += $runtime;
1062                         $this->mTrxWriteAdjQueryCount += 1;
1063                 }
1064         }
1065
1066         private function canRecoverFromDisconnect( $sql, $priorWritesPending ) {
1067                 # Transaction dropped; this can mean lost writes, or REPEATABLE-READ snapshots.
1068                 # Dropped connections also mean that named locks are automatically released.
1069                 # Only allow error suppression in autocommit mode or when the lost transaction
1070                 # didn't matter anyway (aside from DBO_TRX snapshot loss).
1071                 if ( $this->mNamedLocksHeld ) {
1072                         return false; // possible critical section violation
1073                 } elseif ( $sql === 'COMMIT' ) {
1074                         return !$priorWritesPending; // nothing written anyway? (T127428)
1075                 } elseif ( $sql === 'ROLLBACK' ) {
1076                         return true; // transaction lost...which is also what was requested :)
1077                 } elseif ( $this->explicitTrxActive() ) {
1078                         return false; // don't drop atomocity
1079                 } elseif ( $priorWritesPending ) {
1080                         return false; // prior writes lost from implicit transaction
1081                 }
1082
1083                 return true;
1084         }
1085
1086         private function handleTransactionLoss() {
1087                 $this->mTrxLevel = 0;
1088                 $this->mTrxIdleCallbacks = []; // bug 65263
1089                 $this->mTrxPreCommitCallbacks = []; // bug 65263
1090                 try {
1091                         // Handle callbacks in mTrxEndCallbacks
1092                         $this->runOnTransactionIdleCallbacks( self::TRIGGER_ROLLBACK );
1093                         $this->runTransactionListenerCallbacks( self::TRIGGER_ROLLBACK );
1094                         return null;
1095                 } catch ( Exception $e ) {
1096                         // Already logged; move on...
1097                         return $e;
1098                 }
1099         }
1100
1101         public function reportQueryError( $error, $errno, $sql, $fname, $tempIgnore = false ) {
1102                 if ( $this->ignoreErrors() || $tempIgnore ) {
1103                         $this->queryLogger->debug( "SQL ERROR (ignored): $error\n" );
1104                 } else {
1105                         $sql1line = mb_substr( str_replace( "\n", "\\n", $sql ), 0, 5 * 1024 );
1106                         wfLogDBError(
1107                                 "{fname}\t{db_server}\t{errno}\t{error}\t{sql1line}",
1108                                 $this->getLogContext( [
1109                                         'method' => __METHOD__,
1110                                         'errno' => $errno,
1111                                         'error' => $error,
1112                                         'sql1line' => $sql1line,
1113                                         'fname' => $fname,
1114                                 ] )
1115                         );
1116                         $this->queryLogger->debug( "SQL ERROR: " . $error . "\n" );
1117                         throw new DBQueryError( $this, $error, $errno, $sql, $fname );
1118                 }
1119         }
1120
1121         /**
1122          * Intended to be compatible with the PEAR::DB wrapper functions.
1123          * http://pear.php.net/manual/en/package.database.db.intro-execute.php
1124          *
1125          * ? = scalar value, quoted as necessary
1126          * ! = raw SQL bit (a function for instance)
1127          * & = filename; reads the file and inserts as a blob
1128          *     (we don't use this though...)
1129          *
1130          * @param string $sql
1131          * @param string $func
1132          *
1133          * @return array
1134          */
1135         protected function prepare( $sql, $func = 'DatabaseBase::prepare' ) {
1136                 /* MySQL doesn't support prepared statements (yet), so just
1137                  * pack up the query for reference. We'll manually replace
1138                  * the bits later.
1139                  */
1140                 return [ 'query' => $sql, 'func' => $func ];
1141         }
1142
1143         /**
1144          * Free a prepared query, generated by prepare().
1145          * @param string $prepared
1146          */
1147         protected function freePrepared( $prepared ) {
1148                 /* No-op by default */
1149         }
1150
1151         /**
1152          * Execute a prepared query with the various arguments
1153          * @param string $prepared The prepared sql
1154          * @param mixed $args Either an array here, or put scalars as varargs
1155          *
1156          * @return ResultWrapper
1157          */
1158         public function execute( $prepared, $args = null ) {
1159                 if ( !is_array( $args ) ) {
1160                         # Pull the var args
1161                         $args = func_get_args();
1162                         array_shift( $args );
1163                 }
1164
1165                 $sql = $this->fillPrepared( $prepared['query'], $args );
1166
1167                 return $this->query( $sql, $prepared['func'] );
1168         }
1169
1170         /**
1171          * For faking prepared SQL statements on DBs that don't support it directly.
1172          *
1173          * @param string $preparedQuery A 'preparable' SQL statement
1174          * @param array $args Array of Arguments to fill it with
1175          * @return string Executable SQL
1176          */
1177         public function fillPrepared( $preparedQuery, $args ) {
1178                 reset( $args );
1179                 $this->preparedArgs =& $args;
1180
1181                 return preg_replace_callback( '/(\\\\[?!&]|[?!&])/',
1182                         [ &$this, 'fillPreparedArg' ], $preparedQuery );
1183         }
1184
1185         /**
1186          * preg_callback func for fillPrepared()
1187          * The arguments should be in $this->preparedArgs and must not be touched
1188          * while we're doing this.
1189          *
1190          * @param array $matches
1191          * @throws DBUnexpectedError
1192          * @return string
1193          */
1194         protected function fillPreparedArg( $matches ) {
1195                 switch ( $matches[1] ) {
1196                         case '\\?':
1197                                 return '?';
1198                         case '\\!':
1199                                 return '!';
1200                         case '\\&':
1201                                 return '&';
1202                 }
1203
1204                 list( /* $n */, $arg ) = each( $this->preparedArgs );
1205
1206                 switch ( $matches[1] ) {
1207                         case '?':
1208                                 return $this->addQuotes( $arg );
1209                         case '!':
1210                                 return $arg;
1211                         case '&':
1212                                 # return $this->addQuotes( file_get_contents( $arg ) );
1213                                 throw new DBUnexpectedError(
1214                                         $this,
1215                                         '& mode is not implemented. If it\'s really needed, uncomment the line above.'
1216                                 );
1217                         default:
1218                                 throw new DBUnexpectedError(
1219                                         $this,
1220                                         'Received invalid match. This should never happen!'
1221                                 );
1222                 }
1223         }
1224
1225         public function freeResult( $res ) {
1226         }
1227
1228         public function selectField(
1229                 $table, $var, $cond = '', $fname = __METHOD__, $options = []
1230         ) {
1231                 if ( $var === '*' ) { // sanity
1232                         throw new DBUnexpectedError( $this, "Cannot use a * field: got '$var'" );
1233                 }
1234
1235                 if ( !is_array( $options ) ) {
1236                         $options = [ $options ];
1237                 }
1238
1239                 $options['LIMIT'] = 1;
1240
1241                 $res = $this->select( $table, $var, $cond, $fname, $options );
1242                 if ( $res === false || !$this->numRows( $res ) ) {
1243                         return false;
1244                 }
1245
1246                 $row = $this->fetchRow( $res );
1247
1248                 if ( $row !== false ) {
1249                         return reset( $row );
1250                 } else {
1251                         return false;
1252                 }
1253         }
1254
1255         public function selectFieldValues(
1256                 $table, $var, $cond = '', $fname = __METHOD__, $options = [], $join_conds = []
1257         ) {
1258                 if ( $var === '*' ) { // sanity
1259                         throw new DBUnexpectedError( $this, "Cannot use a * field" );
1260                 } elseif ( !is_string( $var ) ) { // sanity
1261                         throw new DBUnexpectedError( $this, "Cannot use an array of fields" );
1262                 }
1263
1264                 if ( !is_array( $options ) ) {
1265                         $options = [ $options ];
1266                 }
1267
1268                 $res = $this->select( $table, $var, $cond, $fname, $options, $join_conds );
1269                 if ( $res === false ) {
1270                         return false;
1271                 }
1272
1273                 $values = [];
1274                 foreach ( $res as $row ) {
1275                         $values[] = $row->$var;
1276                 }
1277
1278                 return $values;
1279         }
1280
1281         /**
1282          * Returns an optional USE INDEX clause to go after the table, and a
1283          * string to go at the end of the query.
1284          *
1285          * @param array $options Associative array of options to be turned into
1286          *   an SQL query, valid keys are listed in the function.
1287          * @return array
1288          * @see DatabaseBase::select()
1289          */
1290         public function makeSelectOptions( $options ) {
1291                 $preLimitTail = $postLimitTail = '';
1292                 $startOpts = '';
1293
1294                 $noKeyOptions = [];
1295
1296                 foreach ( $options as $key => $option ) {
1297                         if ( is_numeric( $key ) ) {
1298                                 $noKeyOptions[$option] = true;
1299                         }
1300                 }
1301
1302                 $preLimitTail .= $this->makeGroupByWithHaving( $options );
1303
1304                 $preLimitTail .= $this->makeOrderBy( $options );
1305
1306                 // if (isset($options['LIMIT'])) {
1307                 //      $tailOpts .= $this->limitResult('', $options['LIMIT'],
1308                 //              isset($options['OFFSET']) ? $options['OFFSET']
1309                 //              : false);
1310                 // }
1311
1312                 if ( isset( $noKeyOptions['FOR UPDATE'] ) ) {
1313                         $postLimitTail .= ' FOR UPDATE';
1314                 }
1315
1316                 if ( isset( $noKeyOptions['LOCK IN SHARE MODE'] ) ) {
1317                         $postLimitTail .= ' LOCK IN SHARE MODE';
1318                 }
1319
1320                 if ( isset( $noKeyOptions['DISTINCT'] ) || isset( $noKeyOptions['DISTINCTROW'] ) ) {
1321                         $startOpts .= 'DISTINCT';
1322                 }
1323
1324                 # Various MySQL extensions
1325                 if ( isset( $noKeyOptions['STRAIGHT_JOIN'] ) ) {
1326                         $startOpts .= ' /*! STRAIGHT_JOIN */';
1327                 }
1328
1329                 if ( isset( $noKeyOptions['HIGH_PRIORITY'] ) ) {
1330                         $startOpts .= ' HIGH_PRIORITY';
1331                 }
1332
1333                 if ( isset( $noKeyOptions['SQL_BIG_RESULT'] ) ) {
1334                         $startOpts .= ' SQL_BIG_RESULT';
1335                 }
1336
1337                 if ( isset( $noKeyOptions['SQL_BUFFER_RESULT'] ) ) {
1338                         $startOpts .= ' SQL_BUFFER_RESULT';
1339                 }
1340
1341                 if ( isset( $noKeyOptions['SQL_SMALL_RESULT'] ) ) {
1342                         $startOpts .= ' SQL_SMALL_RESULT';
1343                 }
1344
1345                 if ( isset( $noKeyOptions['SQL_CALC_FOUND_ROWS'] ) ) {
1346                         $startOpts .= ' SQL_CALC_FOUND_ROWS';
1347                 }
1348
1349                 if ( isset( $noKeyOptions['SQL_CACHE'] ) ) {
1350                         $startOpts .= ' SQL_CACHE';
1351                 }
1352
1353                 if ( isset( $noKeyOptions['SQL_NO_CACHE'] ) ) {
1354                         $startOpts .= ' SQL_NO_CACHE';
1355                 }
1356
1357                 if ( isset( $options['USE INDEX'] ) && is_string( $options['USE INDEX'] ) ) {
1358                         $useIndex = $this->useIndexClause( $options['USE INDEX'] );
1359                 } else {
1360                         $useIndex = '';
1361                 }
1362                 if ( isset( $options['IGNORE INDEX'] ) && is_string( $options['IGNORE INDEX'] ) ) {
1363                         $ignoreIndex = $this->ignoreIndexClause( $options['IGNORE INDEX'] );
1364                 } else {
1365                         $ignoreIndex = '';
1366                 }
1367
1368                 return [ $startOpts, $useIndex, $preLimitTail, $postLimitTail, $ignoreIndex ];
1369         }
1370
1371         /**
1372          * Returns an optional GROUP BY with an optional HAVING
1373          *
1374          * @param array $options Associative array of options
1375          * @return string
1376          * @see DatabaseBase::select()
1377          * @since 1.21
1378          */
1379         public function makeGroupByWithHaving( $options ) {
1380                 $sql = '';
1381                 if ( isset( $options['GROUP BY'] ) ) {
1382                         $gb = is_array( $options['GROUP BY'] )
1383                                 ? implode( ',', $options['GROUP BY'] )
1384                                 : $options['GROUP BY'];
1385                         $sql .= ' GROUP BY ' . $gb;
1386                 }
1387                 if ( isset( $options['HAVING'] ) ) {
1388                         $having = is_array( $options['HAVING'] )
1389                                 ? $this->makeList( $options['HAVING'], LIST_AND )
1390                                 : $options['HAVING'];
1391                         $sql .= ' HAVING ' . $having;
1392                 }
1393
1394                 return $sql;
1395         }
1396
1397         /**
1398          * Returns an optional ORDER BY
1399          *
1400          * @param array $options Associative array of options
1401          * @return string
1402          * @see DatabaseBase::select()
1403          * @since 1.21
1404          */
1405         public function makeOrderBy( $options ) {
1406                 if ( isset( $options['ORDER BY'] ) ) {
1407                         $ob = is_array( $options['ORDER BY'] )
1408                                 ? implode( ',', $options['ORDER BY'] )
1409                                 : $options['ORDER BY'];
1410
1411                         return ' ORDER BY ' . $ob;
1412                 }
1413
1414                 return '';
1415         }
1416
1417         // See IDatabase::select for the docs for this function
1418         public function select( $table, $vars, $conds = '', $fname = __METHOD__,
1419                 $options = [], $join_conds = [] ) {
1420                 $sql = $this->selectSQLText( $table, $vars, $conds, $fname, $options, $join_conds );
1421
1422                 return $this->query( $sql, $fname );
1423         }
1424
1425         public function selectSQLText( $table, $vars, $conds = '', $fname = __METHOD__,
1426                 $options = [], $join_conds = []
1427         ) {
1428                 if ( is_array( $vars ) ) {
1429                         $vars = implode( ',', $this->fieldNamesWithAlias( $vars ) );
1430                 }
1431
1432                 $options = (array)$options;
1433                 $useIndexes = ( isset( $options['USE INDEX'] ) && is_array( $options['USE INDEX'] ) )
1434                         ? $options['USE INDEX']
1435                         : [];
1436                 $ignoreIndexes = ( isset( $options['IGNORE INDEX'] ) && is_array( $options['IGNORE INDEX'] ) )
1437                         ? $options['IGNORE INDEX']
1438                         : [];
1439
1440                 if ( is_array( $table ) ) {
1441                         $from = ' FROM ' .
1442                                 $this->tableNamesWithIndexClauseOrJOIN( $table, $useIndexes, $ignoreIndexes, $join_conds );
1443                 } elseif ( $table != '' ) {
1444                         if ( $table[0] == ' ' ) {
1445                                 $from = ' FROM ' . $table;
1446                         } else {
1447                                 $from = ' FROM ' .
1448                                         $this->tableNamesWithIndexClauseOrJOIN( [ $table ], $useIndexes, $ignoreIndexes, [] );
1449                         }
1450                 } else {
1451                         $from = '';
1452                 }
1453
1454                 list( $startOpts, $useIndex, $preLimitTail, $postLimitTail, $ignoreIndex ) =
1455                         $this->makeSelectOptions( $options );
1456
1457                 if ( !empty( $conds ) ) {
1458                         if ( is_array( $conds ) ) {
1459                                 $conds = $this->makeList( $conds, LIST_AND );
1460                         }
1461                         $sql = "SELECT $startOpts $vars $from $useIndex $ignoreIndex WHERE $conds $preLimitTail";
1462                 } else {
1463                         $sql = "SELECT $startOpts $vars $from $useIndex $ignoreIndex $preLimitTail";
1464                 }
1465
1466                 if ( isset( $options['LIMIT'] ) ) {
1467                         $sql = $this->limitResult( $sql, $options['LIMIT'],
1468                                 isset( $options['OFFSET'] ) ? $options['OFFSET'] : false );
1469                 }
1470                 $sql = "$sql $postLimitTail";
1471
1472                 if ( isset( $options['EXPLAIN'] ) ) {
1473                         $sql = 'EXPLAIN ' . $sql;
1474                 }
1475
1476                 return $sql;
1477         }
1478
1479         public function selectRow( $table, $vars, $conds, $fname = __METHOD__,
1480                 $options = [], $join_conds = []
1481         ) {
1482                 $options = (array)$options;
1483                 $options['LIMIT'] = 1;
1484                 $res = $this->select( $table, $vars, $conds, $fname, $options, $join_conds );
1485
1486                 if ( $res === false ) {
1487                         return false;
1488                 }
1489
1490                 if ( !$this->numRows( $res ) ) {
1491                         return false;
1492                 }
1493
1494                 $obj = $this->fetchObject( $res );
1495
1496                 return $obj;
1497         }
1498
1499         public function estimateRowCount(
1500                 $table, $vars = '*', $conds = '', $fname = __METHOD__, $options = []
1501         ) {
1502                 $rows = 0;
1503                 $res = $this->select( $table, [ 'rowcount' => 'COUNT(*)' ], $conds, $fname, $options );
1504
1505                 if ( $res ) {
1506                         $row = $this->fetchRow( $res );
1507                         $rows = ( isset( $row['rowcount'] ) ) ? (int)$row['rowcount'] : 0;
1508                 }
1509
1510                 return $rows;
1511         }
1512
1513         public function selectRowCount(
1514                 $tables, $vars = '*', $conds = '', $fname = __METHOD__, $options = [], $join_conds = []
1515         ) {
1516                 $rows = 0;
1517                 $sql = $this->selectSQLText( $tables, '1', $conds, $fname, $options, $join_conds );
1518                 $res = $this->query( "SELECT COUNT(*) AS rowcount FROM ($sql) tmp_count", $fname );
1519
1520                 if ( $res ) {
1521                         $row = $this->fetchRow( $res );
1522                         $rows = ( isset( $row['rowcount'] ) ) ? (int)$row['rowcount'] : 0;
1523                 }
1524
1525                 return $rows;
1526         }
1527
1528         /**
1529          * Removes most variables from an SQL query and replaces them with X or N for numbers.
1530          * It's only slightly flawed. Don't use for anything important.
1531          *
1532          * @param string $sql A SQL Query
1533          *
1534          * @return string
1535          */
1536         protected static function generalizeSQL( $sql ) {
1537                 # This does the same as the regexp below would do, but in such a way
1538                 # as to avoid crashing php on some large strings.
1539                 # $sql = preg_replace( "/'([^\\\\']|\\\\.)*'|\"([^\\\\\"]|\\\\.)*\"/", "'X'", $sql );
1540
1541                 $sql = str_replace( "\\\\", '', $sql );
1542                 $sql = str_replace( "\\'", '', $sql );
1543                 $sql = str_replace( "\\\"", '', $sql );
1544                 $sql = preg_replace( "/'.*'/s", "'X'", $sql );
1545                 $sql = preg_replace( '/".*"/s', "'X'", $sql );
1546
1547                 # All newlines, tabs, etc replaced by single space
1548                 $sql = preg_replace( '/\s+/', ' ', $sql );
1549
1550                 # All numbers => N,
1551                 # except the ones surrounded by characters, e.g. l10n
1552                 $sql = preg_replace( '/-?\d+(,-?\d+)+/s', 'N,...,N', $sql );
1553                 $sql = preg_replace( '/(?<![a-zA-Z])-?\d+(?![a-zA-Z])/s', 'N', $sql );
1554
1555                 return $sql;
1556         }
1557
1558         public function fieldExists( $table, $field, $fname = __METHOD__ ) {
1559                 $info = $this->fieldInfo( $table, $field );
1560
1561                 return (bool)$info;
1562         }
1563
1564         public function indexExists( $table, $index, $fname = __METHOD__ ) {
1565                 if ( !$this->tableExists( $table ) ) {
1566                         return null;
1567                 }
1568
1569                 $info = $this->indexInfo( $table, $index, $fname );
1570                 if ( is_null( $info ) ) {
1571                         return null;
1572                 } else {
1573                         return $info !== false;
1574                 }
1575         }
1576
1577         public function tableExists( $table, $fname = __METHOD__ ) {
1578                 $table = $this->tableName( $table );
1579                 $old = $this->ignoreErrors( true );
1580                 $res = $this->query( "SELECT 1 FROM $table LIMIT 1", $fname );
1581                 $this->ignoreErrors( $old );
1582
1583                 return (bool)$res;
1584         }
1585
1586         public function indexUnique( $table, $index ) {
1587                 $indexInfo = $this->indexInfo( $table, $index );
1588
1589                 if ( !$indexInfo ) {
1590                         return null;
1591                 }
1592
1593                 return !$indexInfo[0]->Non_unique;
1594         }
1595
1596         /**
1597          * Helper for DatabaseBase::insert().
1598          *
1599          * @param array $options
1600          * @return string
1601          */
1602         protected function makeInsertOptions( $options ) {
1603                 return implode( ' ', $options );
1604         }
1605
1606         public function insert( $table, $a, $fname = __METHOD__, $options = [] ) {
1607                 # No rows to insert, easy just return now
1608                 if ( !count( $a ) ) {
1609                         return true;
1610                 }
1611
1612                 $table = $this->tableName( $table );
1613
1614                 if ( !is_array( $options ) ) {
1615                         $options = [ $options ];
1616                 }
1617
1618                 $fh = null;
1619                 if ( isset( $options['fileHandle'] ) ) {
1620                         $fh = $options['fileHandle'];
1621                 }
1622                 $options = $this->makeInsertOptions( $options );
1623
1624                 if ( isset( $a[0] ) && is_array( $a[0] ) ) {
1625                         $multi = true;
1626                         $keys = array_keys( $a[0] );
1627                 } else {
1628                         $multi = false;
1629                         $keys = array_keys( $a );
1630                 }
1631
1632                 $sql = 'INSERT ' . $options .
1633                         " INTO $table (" . implode( ',', $keys ) . ') VALUES ';
1634
1635                 if ( $multi ) {
1636                         $first = true;
1637                         foreach ( $a as $row ) {
1638                                 if ( $first ) {
1639                                         $first = false;
1640                                 } else {
1641                                         $sql .= ',';
1642                                 }
1643                                 $sql .= '(' . $this->makeList( $row ) . ')';
1644                         }
1645                 } else {
1646                         $sql .= '(' . $this->makeList( $a ) . ')';
1647                 }
1648
1649                 if ( $fh !== null && false === fwrite( $fh, $sql ) ) {
1650                         return false;
1651                 } elseif ( $fh !== null ) {
1652                         return true;
1653                 }
1654
1655                 return (bool)$this->query( $sql, $fname );
1656         }
1657
1658         /**
1659          * Make UPDATE options array for DatabaseBase::makeUpdateOptions
1660          *
1661          * @param array $options
1662          * @return array
1663          */
1664         protected function makeUpdateOptionsArray( $options ) {
1665                 if ( !is_array( $options ) ) {
1666                         $options = [ $options ];
1667                 }
1668
1669                 $opts = [];
1670
1671                 if ( in_array( 'LOW_PRIORITY', $options ) ) {
1672                         $opts[] = $this->lowPriorityOption();
1673                 }
1674
1675                 if ( in_array( 'IGNORE', $options ) ) {
1676                         $opts[] = 'IGNORE';
1677                 }
1678
1679                 return $opts;
1680         }
1681
1682         /**
1683          * Make UPDATE options for the DatabaseBase::update function
1684          *
1685          * @param array $options The options passed to DatabaseBase::update
1686          * @return string
1687          */
1688         protected function makeUpdateOptions( $options ) {
1689                 $opts = $this->makeUpdateOptionsArray( $options );
1690
1691                 return implode( ' ', $opts );
1692         }
1693
1694         function update( $table, $values, $conds, $fname = __METHOD__, $options = [] ) {
1695                 $table = $this->tableName( $table );
1696                 $opts = $this->makeUpdateOptions( $options );
1697                 $sql = "UPDATE $opts $table SET " . $this->makeList( $values, LIST_SET );
1698
1699                 if ( $conds !== [] && $conds !== '*' ) {
1700                         $sql .= " WHERE " . $this->makeList( $conds, LIST_AND );
1701                 }
1702
1703                 return $this->query( $sql, $fname );
1704         }
1705
1706         public function makeList( $a, $mode = LIST_COMMA ) {
1707                 if ( !is_array( $a ) ) {
1708                         throw new DBUnexpectedError( $this, 'DatabaseBase::makeList called with incorrect parameters' );
1709                 }
1710
1711                 $first = true;
1712                 $list = '';
1713
1714                 foreach ( $a as $field => $value ) {
1715                         if ( !$first ) {
1716                                 if ( $mode == LIST_AND ) {
1717                                         $list .= ' AND ';
1718                                 } elseif ( $mode == LIST_OR ) {
1719                                         $list .= ' OR ';
1720                                 } else {
1721                                         $list .= ',';
1722                                 }
1723                         } else {
1724                                 $first = false;
1725                         }
1726
1727                         if ( ( $mode == LIST_AND || $mode == LIST_OR ) && is_numeric( $field ) ) {
1728                                 $list .= "($value)";
1729                         } elseif ( ( $mode == LIST_SET ) && is_numeric( $field ) ) {
1730                                 $list .= "$value";
1731                         } elseif ( ( $mode == LIST_AND || $mode == LIST_OR ) && is_array( $value ) ) {
1732                                 // Remove null from array to be handled separately if found
1733                                 $includeNull = false;
1734                                 foreach ( array_keys( $value, null, true ) as $nullKey ) {
1735                                         $includeNull = true;
1736                                         unset( $value[$nullKey] );
1737                                 }
1738                                 if ( count( $value ) == 0 && !$includeNull ) {
1739                                         throw new MWException( __METHOD__ . ": empty input for field $field" );
1740                                 } elseif ( count( $value ) == 0 ) {
1741                                         // only check if $field is null
1742                                         $list .= "$field IS NULL";
1743                                 } else {
1744                                         // IN clause contains at least one valid element
1745                                         if ( $includeNull ) {
1746                                                 // Group subconditions to ensure correct precedence
1747                                                 $list .= '(';
1748                                         }
1749                                         if ( count( $value ) == 1 ) {
1750                                                 // Special-case single values, as IN isn't terribly efficient
1751                                                 // Don't necessarily assume the single key is 0; we don't
1752                                                 // enforce linear numeric ordering on other arrays here.
1753                                                 $value = array_values( $value )[0];
1754                                                 $list .= $field . " = " . $this->addQuotes( $value );
1755                                         } else {
1756                                                 $list .= $field . " IN (" . $this->makeList( $value ) . ") ";
1757                                         }
1758                                         // if null present in array, append IS NULL
1759                                         if ( $includeNull ) {
1760                                                 $list .= " OR $field IS NULL)";
1761                                         }
1762                                 }
1763                         } elseif ( $value === null ) {
1764                                 if ( $mode == LIST_AND || $mode == LIST_OR ) {
1765                                         $list .= "$field IS ";
1766                                 } elseif ( $mode == LIST_SET ) {
1767                                         $list .= "$field = ";
1768                                 }
1769                                 $list .= 'NULL';
1770                         } else {
1771                                 if ( $mode == LIST_AND || $mode == LIST_OR || $mode == LIST_SET ) {
1772                                         $list .= "$field = ";
1773                                 }
1774                                 $list .= $mode == LIST_NAMES ? $value : $this->addQuotes( $value );
1775                         }
1776                 }
1777
1778                 return $list;
1779         }
1780
1781         public function makeWhereFrom2d( $data, $baseKey, $subKey ) {
1782                 $conds = [];
1783
1784                 foreach ( $data as $base => $sub ) {
1785                         if ( count( $sub ) ) {
1786                                 $conds[] = $this->makeList(
1787                                         [ $baseKey => $base, $subKey => array_keys( $sub ) ],
1788                                         LIST_AND );
1789                         }
1790                 }
1791
1792                 if ( $conds ) {
1793                         return $this->makeList( $conds, LIST_OR );
1794                 } else {
1795                         // Nothing to search for...
1796                         return false;
1797                 }
1798         }
1799
1800         /**
1801          * Return aggregated value alias
1802          *
1803          * @param array $valuedata
1804          * @param string $valuename
1805          *
1806          * @return string
1807          */
1808         public function aggregateValue( $valuedata, $valuename = 'value' ) {
1809                 return $valuename;
1810         }
1811
1812         public function bitNot( $field ) {
1813                 return "(~$field)";
1814         }
1815
1816         public function bitAnd( $fieldLeft, $fieldRight ) {
1817                 return "($fieldLeft & $fieldRight)";
1818         }
1819
1820         public function bitOr( $fieldLeft, $fieldRight ) {
1821                 return "($fieldLeft | $fieldRight)";
1822         }
1823
1824         public function buildConcat( $stringList ) {
1825                 return 'CONCAT(' . implode( ',', $stringList ) . ')';
1826         }
1827
1828         public function buildGroupConcatField(
1829                 $delim, $table, $field, $conds = '', $join_conds = []
1830         ) {
1831                 $fld = "GROUP_CONCAT($field SEPARATOR " . $this->addQuotes( $delim ) . ')';
1832
1833                 return '(' . $this->selectSQLText( $table, $fld, $conds, null, [], $join_conds ) . ')';
1834         }
1835
1836         /**
1837          * @param string $field Field or column to cast
1838          * @return string
1839          * @since 1.28
1840          */
1841         public function buildStringCast( $field ) {
1842                 return $field;
1843         }
1844
1845         public function selectDB( $db ) {
1846                 # Stub. Shouldn't cause serious problems if it's not overridden, but
1847                 # if your database engine supports a concept similar to MySQL's
1848                 # databases you may as well.
1849                 $this->mDBname = $db;
1850
1851                 return true;
1852         }
1853
1854         public function getDBname() {
1855                 return $this->mDBname;
1856         }
1857
1858         public function getServer() {
1859                 return $this->mServer;
1860         }
1861
1862         /**
1863          * Format a table name ready for use in constructing an SQL query
1864          *
1865          * This does two important things: it quotes the table names to clean them up,
1866          * and it adds a table prefix if only given a table name with no quotes.
1867          *
1868          * All functions of this object which require a table name call this function
1869          * themselves. Pass the canonical name to such functions. This is only needed
1870          * when calling query() directly.
1871          *
1872          * @note This function does not sanitize user input. It is not safe to use
1873          *   this function to escape user input.
1874          * @param string $name Database table name
1875          * @param string $format One of:
1876          *   quoted - Automatically pass the table name through addIdentifierQuotes()
1877          *            so that it can be used in a query.
1878          *   raw - Do not add identifier quotes to the table name
1879          * @return string Full database name
1880          */
1881         public function tableName( $name, $format = 'quoted' ) {
1882                 global $wgSharedDB, $wgSharedPrefix, $wgSharedTables, $wgSharedSchema;
1883                 # Skip the entire process when we have a string quoted on both ends.
1884                 # Note that we check the end so that we will still quote any use of
1885                 # use of `database`.table. But won't break things if someone wants
1886                 # to query a database table with a dot in the name.
1887                 if ( $this->isQuotedIdentifier( $name ) ) {
1888                         return $name;
1889                 }
1890
1891                 # Lets test for any bits of text that should never show up in a table
1892                 # name. Basically anything like JOIN or ON which are actually part of
1893                 # SQL queries, but may end up inside of the table value to combine
1894                 # sql. Such as how the API is doing.
1895                 # Note that we use a whitespace test rather than a \b test to avoid
1896                 # any remote case where a word like on may be inside of a table name
1897                 # surrounded by symbols which may be considered word breaks.
1898                 if ( preg_match( '/(^|\s)(DISTINCT|JOIN|ON|AS)(\s|$)/i', $name ) !== 0 ) {
1899                         return $name;
1900                 }
1901
1902                 # Split database and table into proper variables.
1903                 # We reverse the explode so that database.table and table both output
1904                 # the correct table.
1905                 $dbDetails = explode( '.', $name, 3 );
1906                 if ( count( $dbDetails ) == 3 ) {
1907                         list( $database, $schema, $table ) = $dbDetails;
1908                         # We don't want any prefix added in this case
1909                         $prefix = '';
1910                 } elseif ( count( $dbDetails ) == 2 ) {
1911                         list( $database, $table ) = $dbDetails;
1912                         # We don't want any prefix added in this case
1913                         # In dbs that support it, $database may actually be the schema
1914                         # but that doesn't affect any of the functionality here
1915                         $prefix = '';
1916                         $schema = null;
1917                 } else {
1918                         list( $table ) = $dbDetails;
1919                         if ( $wgSharedDB !== null # We have a shared database
1920                                 && $this->mForeign == false # We're not working on a foreign database
1921                                 && !$this->isQuotedIdentifier( $table ) # Prevent shared tables listing '`table`'
1922                                 && in_array( $table, $wgSharedTables ) # A shared table is selected
1923                         ) {
1924                                 $database = $wgSharedDB;
1925                                 $schema = $wgSharedSchema === null ? $this->mSchema : $wgSharedSchema;
1926                                 $prefix = $wgSharedPrefix === null ? $this->mTablePrefix : $wgSharedPrefix;
1927                         } else {
1928                                 $database = null;
1929                                 $schema = $this->mSchema; # Default schema
1930                                 $prefix = $this->mTablePrefix; # Default prefix
1931                         }
1932                 }
1933
1934                 # Quote $table and apply the prefix if not quoted.
1935                 # $tableName might be empty if this is called from Database::replaceVars()
1936                 $tableName = "{$prefix}{$table}";
1937                 if ( $format == 'quoted' && !$this->isQuotedIdentifier( $tableName ) && $tableName !== '' ) {
1938                         $tableName = $this->addIdentifierQuotes( $tableName );
1939                 }
1940
1941                 # Quote $schema and merge it with the table name if needed
1942                 if ( strlen( $schema ) ) {
1943                         if ( $format == 'quoted' && !$this->isQuotedIdentifier( $schema ) ) {
1944                                 $schema = $this->addIdentifierQuotes( $schema );
1945                         }
1946                         $tableName = $schema . '.' . $tableName;
1947                 }
1948
1949                 # Quote $database and merge it with the table name if needed
1950                 if ( $database !== null ) {
1951                         if ( $format == 'quoted' && !$this->isQuotedIdentifier( $database ) ) {
1952                                 $database = $this->addIdentifierQuotes( $database );
1953                         }
1954                         $tableName = $database . '.' . $tableName;
1955                 }
1956
1957                 return $tableName;
1958         }
1959
1960         /**
1961          * Fetch a number of table names into an array
1962          * This is handy when you need to construct SQL for joins
1963          *
1964          * Example:
1965          * extract( $dbr->tableNames( 'user', 'watchlist' ) );
1966          * $sql = "SELECT wl_namespace,wl_title FROM $watchlist,$user
1967          *         WHERE wl_user=user_id AND wl_user=$nameWithQuotes";
1968          *
1969          * @return array
1970          */
1971         public function tableNames() {
1972                 $inArray = func_get_args();
1973                 $retVal = [];
1974
1975                 foreach ( $inArray as $name ) {
1976                         $retVal[$name] = $this->tableName( $name );
1977                 }
1978
1979                 return $retVal;
1980         }
1981
1982         /**
1983          * Fetch a number of table names into an zero-indexed numerical array
1984          * This is handy when you need to construct SQL for joins
1985          *
1986          * Example:
1987          * list( $user, $watchlist ) = $dbr->tableNamesN( 'user', 'watchlist' );
1988          * $sql = "SELECT wl_namespace,wl_title FROM $watchlist,$user
1989          *         WHERE wl_user=user_id AND wl_user=$nameWithQuotes";
1990          *
1991          * @return array
1992          */
1993         public function tableNamesN() {
1994                 $inArray = func_get_args();
1995                 $retVal = [];
1996
1997                 foreach ( $inArray as $name ) {
1998                         $retVal[] = $this->tableName( $name );
1999                 }
2000
2001                 return $retVal;
2002         }
2003
2004         /**
2005          * Get an aliased table name
2006          * e.g. tableName AS newTableName
2007          *
2008          * @param string $name Table name, see tableName()
2009          * @param string|bool $alias Alias (optional)
2010          * @return string SQL name for aliased table. Will not alias a table to its own name
2011          */
2012         public function tableNameWithAlias( $name, $alias = false ) {
2013                 if ( !$alias || $alias == $name ) {
2014                         return $this->tableName( $name );
2015                 } else {
2016                         return $this->tableName( $name ) . ' ' . $this->addIdentifierQuotes( $alias );
2017                 }
2018         }
2019
2020         /**
2021          * Gets an array of aliased table names
2022          *
2023          * @param array $tables [ [alias] => table ]
2024          * @return string[] See tableNameWithAlias()
2025          */
2026         public function tableNamesWithAlias( $tables ) {
2027                 $retval = [];
2028                 foreach ( $tables as $alias => $table ) {
2029                         if ( is_numeric( $alias ) ) {
2030                                 $alias = $table;
2031                         }
2032                         $retval[] = $this->tableNameWithAlias( $table, $alias );
2033                 }
2034
2035                 return $retval;
2036         }
2037
2038         /**
2039          * Get an aliased field name
2040          * e.g. fieldName AS newFieldName
2041          *
2042          * @param string $name Field name
2043          * @param string|bool $alias Alias (optional)
2044          * @return string SQL name for aliased field. Will not alias a field to its own name
2045          */
2046         public function fieldNameWithAlias( $name, $alias = false ) {
2047                 if ( !$alias || (string)$alias === (string)$name ) {
2048                         return $name;
2049                 } else {
2050                         return $name . ' AS ' . $this->addIdentifierQuotes( $alias ); // PostgreSQL needs AS
2051                 }
2052         }
2053
2054         /**
2055          * Gets an array of aliased field names
2056          *
2057          * @param array $fields [ [alias] => field ]
2058          * @return string[] See fieldNameWithAlias()
2059          */
2060         public function fieldNamesWithAlias( $fields ) {
2061                 $retval = [];
2062                 foreach ( $fields as $alias => $field ) {
2063                         if ( is_numeric( $alias ) ) {
2064                                 $alias = $field;
2065                         }
2066                         $retval[] = $this->fieldNameWithAlias( $field, $alias );
2067                 }
2068
2069                 return $retval;
2070         }
2071
2072         /**
2073          * Get the aliased table name clause for a FROM clause
2074          * which might have a JOIN and/or USE INDEX or IGNORE INDEX clause
2075          *
2076          * @param array $tables ( [alias] => table )
2077          * @param array $use_index Same as for select()
2078          * @param array $ignore_index Same as for select()
2079          * @param array $join_conds Same as for select()
2080          * @return string
2081          */
2082         protected function tableNamesWithIndexClauseOrJOIN(
2083                 $tables, $use_index = [], $ignore_index = [], $join_conds = []
2084         ) {
2085                 $ret = [];
2086                 $retJOIN = [];
2087                 $use_index = (array)$use_index;
2088                 $ignore_index = (array)$ignore_index;
2089                 $join_conds = (array)$join_conds;
2090
2091                 foreach ( $tables as $alias => $table ) {
2092                         if ( !is_string( $alias ) ) {
2093                                 // No alias? Set it equal to the table name
2094                                 $alias = $table;
2095                         }
2096                         // Is there a JOIN clause for this table?
2097                         if ( isset( $join_conds[$alias] ) ) {
2098                                 list( $joinType, $conds ) = $join_conds[$alias];
2099                                 $tableClause = $joinType;
2100                                 $tableClause .= ' ' . $this->tableNameWithAlias( $table, $alias );
2101                                 if ( isset( $use_index[$alias] ) ) { // has USE INDEX?
2102                                         $use = $this->useIndexClause( implode( ',', (array)$use_index[$alias] ) );
2103                                         if ( $use != '' ) {
2104                                                 $tableClause .= ' ' . $use;
2105                                         }
2106                                 }
2107                                 if ( isset( $ignore_index[$alias] ) ) { // has IGNORE INDEX?
2108                                         $ignore = $this->ignoreIndexClause( implode( ',', (array)$ignore_index[$alias] ) );
2109                                         if ( $ignore != '' ) {
2110                                                 $tableClause .= ' ' . $ignore;
2111                                         }
2112                                 }
2113                                 $on = $this->makeList( (array)$conds, LIST_AND );
2114                                 if ( $on != '' ) {
2115                                         $tableClause .= ' ON (' . $on . ')';
2116                                 }
2117
2118                                 $retJOIN[] = $tableClause;
2119                         } elseif ( isset( $use_index[$alias] ) ) {
2120                                 // Is there an INDEX clause for this table?
2121                                 $tableClause = $this->tableNameWithAlias( $table, $alias );
2122                                 $tableClause .= ' ' . $this->useIndexClause(
2123                                         implode( ',', (array)$use_index[$alias] )
2124                                 );
2125
2126                                 $ret[] = $tableClause;
2127                         } elseif ( isset( $ignore_index[$alias] ) ) {
2128                                 // Is there an INDEX clause for this table?
2129                                 $tableClause = $this->tableNameWithAlias( $table, $alias );
2130                                 $tableClause .= ' ' . $this->ignoreIndexClause(
2131                                         implode( ',', (array)$ignore_index[$alias] )
2132                                 );
2133
2134                                 $ret[] = $tableClause;
2135                         } else {
2136                                 $tableClause = $this->tableNameWithAlias( $table, $alias );
2137
2138                                 $ret[] = $tableClause;
2139                         }
2140                 }
2141
2142                 // We can't separate explicit JOIN clauses with ',', use ' ' for those
2143                 $implicitJoins = !empty( $ret ) ? implode( ',', $ret ) : "";
2144                 $explicitJoins = !empty( $retJOIN ) ? implode( ' ', $retJOIN ) : "";
2145
2146                 // Compile our final table clause
2147                 return implode( ' ', [ $implicitJoins, $explicitJoins ] );
2148         }
2149
2150         /**
2151          * Get the name of an index in a given table.
2152          *
2153          * @param string $index
2154          * @return string
2155          */
2156         protected function indexName( $index ) {
2157                 // Backwards-compatibility hack
2158                 $renamed = [
2159                         'ar_usertext_timestamp' => 'usertext_timestamp',
2160                         'un_user_id' => 'user_id',
2161                         'un_user_ip' => 'user_ip',
2162                 ];
2163
2164                 if ( isset( $renamed[$index] ) ) {
2165                         return $renamed[$index];
2166                 } else {
2167                         return $index;
2168                 }
2169         }
2170
2171         public function addQuotes( $s ) {
2172                 if ( $s instanceof Blob ) {
2173                         $s = $s->fetch();
2174                 }
2175                 if ( $s === null ) {
2176                         return 'NULL';
2177                 } else {
2178                         # This will also quote numeric values. This should be harmless,
2179                         # and protects against weird problems that occur when they really
2180                         # _are_ strings such as article titles and string->number->string
2181                         # conversion is not 1:1.
2182                         return "'" . $this->strencode( $s ) . "'";
2183                 }
2184         }
2185
2186         /**
2187          * Quotes an identifier using `backticks` or "double quotes" depending on the database type.
2188          * MySQL uses `backticks` while basically everything else uses double quotes.
2189          * Since MySQL is the odd one out here the double quotes are our generic
2190          * and we implement backticks in DatabaseMysql.
2191          *
2192          * @param string $s
2193          * @return string
2194          */
2195         public function addIdentifierQuotes( $s ) {
2196                 return '"' . str_replace( '"', '""', $s ) . '"';
2197         }
2198
2199         /**
2200          * Returns if the given identifier looks quoted or not according to
2201          * the database convention for quoting identifiers .
2202          *
2203          * @note Do not use this to determine if untrusted input is safe.
2204          *   A malicious user can trick this function.
2205          * @param string $name
2206          * @return bool
2207          */
2208         public function isQuotedIdentifier( $name ) {
2209                 return $name[0] == '"' && substr( $name, -1, 1 ) == '"';
2210         }
2211
2212         /**
2213          * @param string $s
2214          * @return string
2215          */
2216         protected function escapeLikeInternal( $s ) {
2217                 return addcslashes( $s, '\%_' );
2218         }
2219
2220         public function buildLike() {
2221                 $params = func_get_args();
2222
2223                 if ( count( $params ) > 0 && is_array( $params[0] ) ) {
2224                         $params = $params[0];
2225                 }
2226
2227                 $s = '';
2228
2229                 foreach ( $params as $value ) {
2230                         if ( $value instanceof LikeMatch ) {
2231                                 $s .= $value->toString();
2232                         } else {
2233                                 $s .= $this->escapeLikeInternal( $value );
2234                         }
2235                 }
2236
2237                 return " LIKE {$this->addQuotes( $s )} ";
2238         }
2239
2240         public function anyChar() {
2241                 return new LikeMatch( '_' );
2242         }
2243
2244         public function anyString() {
2245                 return new LikeMatch( '%' );
2246         }
2247
2248         public function nextSequenceValue( $seqName ) {
2249                 return null;
2250         }
2251
2252         /**
2253          * USE INDEX clause. Unlikely to be useful for anything but MySQL. This
2254          * is only needed because a) MySQL must be as efficient as possible due to
2255          * its use on Wikipedia, and b) MySQL 4.0 is kind of dumb sometimes about
2256          * which index to pick. Anyway, other databases might have different
2257          * indexes on a given table. So don't bother overriding this unless you're
2258          * MySQL.
2259          * @param string $index
2260          * @return string
2261          */
2262         public function useIndexClause( $index ) {
2263                 return '';
2264         }
2265
2266         /**
2267          * IGNORE INDEX clause. Unlikely to be useful for anything but MySQL. This
2268          * is only needed because a) MySQL must be as efficient as possible due to
2269          * its use on Wikipedia, and b) MySQL 4.0 is kind of dumb sometimes about
2270          * which index to pick. Anyway, other databases might have different
2271          * indexes on a given table. So don't bother overriding this unless you're
2272          * MySQL.
2273          * @param string $index
2274          * @return string
2275          */
2276         public function ignoreIndexClause( $index ) {
2277                 return '';
2278         }
2279
2280         public function replace( $table, $uniqueIndexes, $rows, $fname = __METHOD__ ) {
2281                 $quotedTable = $this->tableName( $table );
2282
2283                 if ( count( $rows ) == 0 ) {
2284                         return;
2285                 }
2286
2287                 # Single row case
2288                 if ( !is_array( reset( $rows ) ) ) {
2289                         $rows = [ $rows ];
2290                 }
2291
2292                 // @FXIME: this is not atomic, but a trx would break affectedRows()
2293                 foreach ( $rows as $row ) {
2294                         # Delete rows which collide
2295                         if ( $uniqueIndexes ) {
2296                                 $sql = "DELETE FROM $quotedTable WHERE ";
2297                                 $first = true;
2298                                 foreach ( $uniqueIndexes as $index ) {
2299                                         if ( $first ) {
2300                                                 $first = false;
2301                                                 $sql .= '( ';
2302                                         } else {
2303                                                 $sql .= ' ) OR ( ';
2304                                         }
2305                                         if ( is_array( $index ) ) {
2306                                                 $first2 = true;
2307                                                 foreach ( $index as $col ) {
2308                                                         if ( $first2 ) {
2309                                                                 $first2 = false;
2310                                                         } else {
2311                                                                 $sql .= ' AND ';
2312                                                         }
2313                                                         $sql .= $col . '=' . $this->addQuotes( $row[$col] );
2314                                                 }
2315                                         } else {
2316                                                 $sql .= $index . '=' . $this->addQuotes( $row[$index] );
2317                                         }
2318                                 }
2319                                 $sql .= ' )';
2320                                 $this->query( $sql, $fname );
2321                         }
2322
2323                         # Now insert the row
2324                         $this->insert( $table, $row, $fname );
2325                 }
2326         }
2327
2328         /**
2329          * REPLACE query wrapper for MySQL and SQLite, which have a native REPLACE
2330          * statement.
2331          *
2332          * @param string $table Table name
2333          * @param array|string $rows Row(s) to insert
2334          * @param string $fname Caller function name
2335          *
2336          * @return ResultWrapper
2337          */
2338         protected function nativeReplace( $table, $rows, $fname ) {
2339                 $table = $this->tableName( $table );
2340
2341                 # Single row case
2342                 if ( !is_array( reset( $rows ) ) ) {
2343                         $rows = [ $rows ];
2344                 }
2345
2346                 $sql = "REPLACE INTO $table (" . implode( ',', array_keys( $rows[0] ) ) . ') VALUES ';
2347                 $first = true;
2348
2349                 foreach ( $rows as $row ) {
2350                         if ( $first ) {
2351                                 $first = false;
2352                         } else {
2353                                 $sql .= ',';
2354                         }
2355
2356                         $sql .= '(' . $this->makeList( $row ) . ')';
2357                 }
2358
2359                 return $this->query( $sql, $fname );
2360         }
2361
2362         public function upsert( $table, array $rows, array $uniqueIndexes, array $set,
2363                 $fname = __METHOD__
2364         ) {
2365                 if ( !count( $rows ) ) {
2366                         return true; // nothing to do
2367                 }
2368
2369                 if ( !is_array( reset( $rows ) ) ) {
2370                         $rows = [ $rows ];
2371                 }
2372
2373                 if ( count( $uniqueIndexes ) ) {
2374                         $clauses = []; // list WHERE clauses that each identify a single row
2375                         foreach ( $rows as $row ) {
2376                                 foreach ( $uniqueIndexes as $index ) {
2377                                         $index = is_array( $index ) ? $index : [ $index ]; // columns
2378                                         $rowKey = []; // unique key to this row
2379                                         foreach ( $index as $column ) {
2380                                                 $rowKey[$column] = $row[$column];
2381                                         }
2382                                         $clauses[] = $this->makeList( $rowKey, LIST_AND );
2383                                 }
2384                         }
2385                         $where = [ $this->makeList( $clauses, LIST_OR ) ];
2386                 } else {
2387                         $where = false;
2388                 }
2389
2390                 $useTrx = !$this->mTrxLevel;
2391                 if ( $useTrx ) {
2392                         $this->begin( $fname, self::TRANSACTION_INTERNAL );
2393                 }
2394                 try {
2395                         # Update any existing conflicting row(s)
2396                         if ( $where !== false ) {
2397                                 $ok = $this->update( $table, $set, $where, $fname );
2398                         } else {
2399                                 $ok = true;
2400                         }
2401                         # Now insert any non-conflicting row(s)
2402                         $ok = $this->insert( $table, $rows, $fname, [ 'IGNORE' ] ) && $ok;
2403                 } catch ( Exception $e ) {
2404                         if ( $useTrx ) {
2405                                 $this->rollback( $fname, self::FLUSHING_INTERNAL );
2406                         }
2407                         throw $e;
2408                 }
2409                 if ( $useTrx ) {
2410                         $this->commit( $fname, self::FLUSHING_INTERNAL );
2411                 }
2412
2413                 return $ok;
2414         }
2415
2416         public function deleteJoin( $delTable, $joinTable, $delVar, $joinVar, $conds,
2417                 $fname = __METHOD__
2418         ) {
2419                 if ( !$conds ) {
2420                         throw new DBUnexpectedError( $this,
2421                                 'DatabaseBase::deleteJoin() called with empty $conds' );
2422                 }
2423
2424                 $delTable = $this->tableName( $delTable );
2425                 $joinTable = $this->tableName( $joinTable );
2426                 $sql = "DELETE FROM $delTable WHERE $delVar IN (SELECT $joinVar FROM $joinTable ";
2427                 if ( $conds != '*' ) {
2428                         $sql .= 'WHERE ' . $this->makeList( $conds, LIST_AND );
2429                 }
2430                 $sql .= ')';
2431
2432                 $this->query( $sql, $fname );
2433         }
2434
2435         /**
2436          * Returns the size of a text field, or -1 for "unlimited"
2437          *
2438          * @param string $table
2439          * @param string $field
2440          * @return int
2441          */
2442         public function textFieldSize( $table, $field ) {
2443                 $table = $this->tableName( $table );
2444                 $sql = "SHOW COLUMNS FROM $table LIKE \"$field\";";
2445                 $res = $this->query( $sql, 'DatabaseBase::textFieldSize' );
2446                 $row = $this->fetchObject( $res );
2447
2448                 $m = [];
2449
2450                 if ( preg_match( '/\((.*)\)/', $row->Type, $m ) ) {
2451                         $size = $m[1];
2452                 } else {
2453                         $size = -1;
2454                 }
2455
2456                 return $size;
2457         }
2458
2459         /**
2460          * A string to insert into queries to show that they're low-priority, like
2461          * MySQL's LOW_PRIORITY. If no such feature exists, return an empty
2462          * string and nothing bad should happen.
2463          *
2464          * @return string Returns the text of the low priority option if it is
2465          *   supported, or a blank string otherwise
2466          */
2467         public function lowPriorityOption() {
2468                 return '';
2469         }
2470
2471         public function delete( $table, $conds, $fname = __METHOD__ ) {
2472                 if ( !$conds ) {
2473                         throw new DBUnexpectedError( $this, 'DatabaseBase::delete() called with no conditions' );
2474                 }
2475
2476                 $table = $this->tableName( $table );
2477                 $sql = "DELETE FROM $table";
2478
2479                 if ( $conds != '*' ) {
2480                         if ( is_array( $conds ) ) {
2481                                 $conds = $this->makeList( $conds, LIST_AND );
2482                         }
2483                         $sql .= ' WHERE ' . $conds;
2484                 }
2485
2486                 return $this->query( $sql, $fname );
2487         }
2488
2489         public function insertSelect(
2490                 $destTable, $srcTable, $varMap, $conds,
2491                 $fname = __METHOD__, $insertOptions = [], $selectOptions = []
2492         ) {
2493                 if ( $this->cliMode ) {
2494                         // For massive migrations with downtime, we don't want to select everything
2495                         // into memory and OOM, so do all this native on the server side if possible.
2496                         return $this->nativeInsertSelect(
2497                                 $destTable,
2498                                 $srcTable,
2499                                 $varMap,
2500                                 $conds,
2501                                 $fname,
2502                                 $insertOptions,
2503                                 $selectOptions
2504                         );
2505                 }
2506
2507                 // For web requests, do a locking SELECT and then INSERT. This puts the SELECT burden
2508                 // on only the master (without needing row-based-replication). It also makes it easy to
2509                 // know how big the INSERT is going to be.
2510                 $fields = [];
2511                 foreach ( $varMap as $dstColumn => $sourceColumnOrSql ) {
2512                         $fields[] = $this->fieldNameWithAlias( $sourceColumnOrSql, $dstColumn );
2513                 }
2514                 $selectOptions[] = 'FOR UPDATE';
2515                 $res = $this->select( $srcTable, implode( ',', $fields ), $conds, $fname, $selectOptions );
2516                 if ( !$res ) {
2517                         return false;
2518                 }
2519
2520                 $rows = [];
2521                 foreach ( $res as $row ) {
2522                         $rows[] = (array)$row;
2523                 }
2524
2525                 return $this->insert( $destTable, $rows, $fname, $insertOptions );
2526         }
2527
2528         public function nativeInsertSelect( $destTable, $srcTable, $varMap, $conds,
2529                 $fname = __METHOD__,
2530                 $insertOptions = [], $selectOptions = []
2531         ) {
2532                 $destTable = $this->tableName( $destTable );
2533
2534                 if ( !is_array( $insertOptions ) ) {
2535                         $insertOptions = [ $insertOptions ];
2536                 }
2537
2538                 $insertOptions = $this->makeInsertOptions( $insertOptions );
2539
2540                 if ( !is_array( $selectOptions ) ) {
2541                         $selectOptions = [ $selectOptions ];
2542                 }
2543
2544                 list( $startOpts, $useIndex, $tailOpts, $ignoreIndex ) = $this->makeSelectOptions(
2545                         $selectOptions );
2546
2547                 if ( is_array( $srcTable ) ) {
2548                         $srcTable = implode( ',', array_map( [ &$this, 'tableName' ], $srcTable ) );
2549                 } else {
2550                         $srcTable = $this->tableName( $srcTable );
2551                 }
2552
2553                 $sql = "INSERT $insertOptions INTO $destTable (" . implode( ',', array_keys( $varMap ) ) . ')' .
2554                         " SELECT $startOpts " . implode( ',', $varMap ) .
2555                         " FROM $srcTable $useIndex $ignoreIndex ";
2556
2557                 if ( $conds != '*' ) {
2558                         if ( is_array( $conds ) ) {
2559                                 $conds = $this->makeList( $conds, LIST_AND );
2560                         }
2561                         $sql .= " WHERE $conds";
2562                 }
2563
2564                 $sql .= " $tailOpts";
2565
2566                 return $this->query( $sql, $fname );
2567         }
2568
2569         /**
2570          * Construct a LIMIT query with optional offset. This is used for query
2571          * pages. The SQL should be adjusted so that only the first $limit rows
2572          * are returned. If $offset is provided as well, then the first $offset
2573          * rows should be discarded, and the next $limit rows should be returned.
2574          * If the result of the query is not ordered, then the rows to be returned
2575          * are theoretically arbitrary.
2576          *
2577          * $sql is expected to be a SELECT, if that makes a difference.
2578          *
2579          * The version provided by default works in MySQL and SQLite. It will very
2580          * likely need to be overridden for most other DBMSes.
2581          *
2582          * @param string $sql SQL query we will append the limit too
2583          * @param int $limit The SQL limit
2584          * @param int|bool $offset The SQL offset (default false)
2585          * @throws DBUnexpectedError
2586          * @return string
2587          */
2588         public function limitResult( $sql, $limit, $offset = false ) {
2589                 if ( !is_numeric( $limit ) ) {
2590                         throw new DBUnexpectedError( $this, "Invalid non-numeric limit passed to limitResult()\n" );
2591                 }
2592
2593                 return "$sql LIMIT "
2594                         . ( ( is_numeric( $offset ) && $offset != 0 ) ? "{$offset}," : "" )
2595                         . "{$limit} ";
2596         }
2597
2598         public function unionSupportsOrderAndLimit() {
2599                 return true; // True for almost every DB supported
2600         }
2601
2602         public function unionQueries( $sqls, $all ) {
2603                 $glue = $all ? ') UNION ALL (' : ') UNION (';
2604
2605                 return '(' . implode( $glue, $sqls ) . ')';
2606         }
2607
2608         public function conditional( $cond, $trueVal, $falseVal ) {
2609                 if ( is_array( $cond ) ) {
2610                         $cond = $this->makeList( $cond, LIST_AND );
2611                 }
2612
2613                 return " (CASE WHEN $cond THEN $trueVal ELSE $falseVal END) ";
2614         }
2615
2616         public function strreplace( $orig, $old, $new ) {
2617                 return "REPLACE({$orig}, {$old}, {$new})";
2618         }
2619
2620         public function getServerUptime() {
2621                 return 0;
2622         }
2623
2624         public function wasDeadlock() {
2625                 return false;
2626         }
2627
2628         public function wasLockTimeout() {
2629                 return false;
2630         }
2631
2632         public function wasErrorReissuable() {
2633                 return false;
2634         }
2635
2636         public function wasReadOnlyError() {
2637                 return false;
2638         }
2639
2640         /**
2641          * Determines if the given query error was a connection drop
2642          * STUB
2643          *
2644          * @param integer|string $errno
2645          * @return bool
2646          */
2647         public function wasConnectionError( $errno ) {
2648                 return false;
2649         }
2650
2651         /**
2652          * Perform a deadlock-prone transaction.
2653          *
2654          * This function invokes a callback function to perform a set of write
2655          * queries. If a deadlock occurs during the processing, the transaction
2656          * will be rolled back and the callback function will be called again.
2657          *
2658          * Avoid using this method outside of Job or Maintenance classes.
2659          *
2660          * Usage:
2661          *   $dbw->deadlockLoop( callback, ... );
2662          *
2663          * Extra arguments are passed through to the specified callback function.
2664          * This method requires that no transactions are already active to avoid
2665          * causing premature commits or exceptions.
2666          *
2667          * Returns whatever the callback function returned on its successful,
2668          * iteration, or false on error, for example if the retry limit was
2669          * reached.
2670          *
2671          * @return mixed
2672          * @throws DBUnexpectedError
2673          * @throws Exception
2674          */
2675         public function deadlockLoop() {
2676                 $args = func_get_args();
2677                 $function = array_shift( $args );
2678                 $tries = self::DEADLOCK_TRIES;
2679
2680                 $this->begin( __METHOD__ );
2681
2682                 $retVal = null;
2683                 /** @var Exception $e */
2684                 $e = null;
2685                 do {
2686                         try {
2687                                 $retVal = call_user_func_array( $function, $args );
2688                                 break;
2689                         } catch ( DBQueryError $e ) {
2690                                 if ( $this->wasDeadlock() ) {
2691                                         // Retry after a randomized delay
2692                                         usleep( mt_rand( self::DEADLOCK_DELAY_MIN, self::DEADLOCK_DELAY_MAX ) );
2693                                 } else {
2694                                         // Throw the error back up
2695                                         throw $e;
2696                                 }
2697                         }
2698                 } while ( --$tries > 0 );
2699
2700                 if ( $tries <= 0 ) {
2701                         // Too many deadlocks; give up
2702                         $this->rollback( __METHOD__ );
2703                         throw $e;
2704                 } else {
2705                         $this->commit( __METHOD__ );
2706
2707                         return $retVal;
2708                 }
2709         }
2710
2711         public function masterPosWait( DBMasterPos $pos, $timeout ) {
2712                 # Real waits are implemented in the subclass.
2713                 return 0;
2714         }
2715
2716         public function getSlavePos() {
2717                 # Stub
2718                 return false;
2719         }
2720
2721         public function getMasterPos() {
2722                 # Stub
2723                 return false;
2724         }
2725
2726         public function serverIsReadOnly() {
2727                 return false;
2728         }
2729
2730         final public function onTransactionResolution( callable $callback ) {
2731                 if ( !$this->mTrxLevel ) {
2732                         throw new DBUnexpectedError( $this, "No transaction is active." );
2733                 }
2734                 $this->mTrxEndCallbacks[] = [ $callback, wfGetCaller() ];
2735         }
2736
2737         final public function onTransactionIdle( callable $callback ) {
2738                 $this->mTrxIdleCallbacks[] = [ $callback, wfGetCaller() ];
2739                 if ( !$this->mTrxLevel ) {
2740                         $this->runOnTransactionIdleCallbacks( self::TRIGGER_IDLE );
2741                 }
2742         }
2743
2744         final public function onTransactionPreCommitOrIdle( callable $callback ) {
2745                 if ( $this->mTrxLevel ) {
2746                         $this->mTrxPreCommitCallbacks[] = [ $callback, wfGetCaller() ];
2747                 } else {
2748                         // If no transaction is active, then make one for this callback
2749                         $this->startAtomic( __METHOD__ );
2750                         try {
2751                                 call_user_func( $callback );
2752                                 $this->endAtomic( __METHOD__ );
2753                         } catch ( Exception $e ) {
2754                                 $this->rollback( __METHOD__, self::FLUSHING_INTERNAL );
2755                                 throw $e;
2756                         }
2757                 }
2758         }
2759
2760         final public function setTransactionListener( $name, callable $callback = null ) {
2761                 if ( $callback ) {
2762                         $this->mTrxRecurringCallbacks[$name] = [ $callback, wfGetCaller() ];
2763                 } else {
2764                         unset( $this->mTrxRecurringCallbacks[$name] );
2765                 }
2766         }
2767
2768         /**
2769          * Whether to disable running of post-COMMIT/ROLLBACK callbacks
2770          *
2771          * This method should not be used outside of Database/LoadBalancer
2772          *
2773          * @param bool $suppress
2774          * @since 1.28
2775          */
2776         final public function setTrxEndCallbackSuppression( $suppress ) {
2777                 $this->mTrxEndCallbacksSuppressed = $suppress;
2778         }
2779
2780         /**
2781          * Actually run and consume any "on transaction idle/resolution" callbacks.
2782          *
2783          * This method should not be used outside of Database/LoadBalancer
2784          *
2785          * @param integer $trigger IDatabase::TRIGGER_* constant
2786          * @since 1.20
2787          * @throws Exception
2788          */
2789         public function runOnTransactionIdleCallbacks( $trigger ) {
2790                 if ( $this->mTrxEndCallbacksSuppressed ) {
2791                         return;
2792                 }
2793
2794                 $autoTrx = $this->getFlag( DBO_TRX ); // automatic begin() enabled?
2795                 /** @var Exception $e */
2796                 $e = null; // first exception
2797                 do { // callbacks may add callbacks :)
2798                         $callbacks = array_merge(
2799                                 $this->mTrxIdleCallbacks,
2800                                 $this->mTrxEndCallbacks // include "transaction resolution" callbacks
2801                         );
2802                         $this->mTrxIdleCallbacks = []; // consumed (and recursion guard)
2803                         $this->mTrxEndCallbacks = []; // consumed (recursion guard)
2804                         foreach ( $callbacks as $callback ) {
2805                                 try {
2806                                         list( $phpCallback ) = $callback;
2807                                         $this->clearFlag( DBO_TRX ); // make each query its own transaction
2808                                         call_user_func_array( $phpCallback, [ $trigger ] );
2809                                         if ( $autoTrx ) {
2810                                                 $this->setFlag( DBO_TRX ); // restore automatic begin()
2811                                         } else {
2812                                                 $this->clearFlag( DBO_TRX ); // restore auto-commit
2813                                         }
2814                                 } catch ( Exception $ex ) {
2815                                         MWExceptionHandler::logException( $ex );
2816                                         $e = $e ?: $ex;
2817                                         // Some callbacks may use startAtomic/endAtomic, so make sure
2818                                         // their transactions are ended so other callbacks don't fail
2819                                         if ( $this->trxLevel() ) {
2820                                                 $this->rollback( __METHOD__, self::FLUSHING_INTERNAL );
2821                                         }
2822                                 }
2823                         }
2824                 } while ( count( $this->mTrxIdleCallbacks ) );
2825
2826                 if ( $e instanceof Exception ) {
2827                         throw $e; // re-throw any first exception
2828                 }
2829         }
2830
2831         /**
2832          * Actually run and consume any "on transaction pre-commit" callbacks.
2833          *
2834          * This method should not be used outside of Database/LoadBalancer
2835          *
2836          * @since 1.22
2837          * @throws Exception
2838          */
2839         public function runOnTransactionPreCommitCallbacks() {
2840                 $e = null; // first exception
2841                 do { // callbacks may add callbacks :)
2842                         $callbacks = $this->mTrxPreCommitCallbacks;
2843                         $this->mTrxPreCommitCallbacks = []; // consumed (and recursion guard)
2844                         foreach ( $callbacks as $callback ) {
2845                                 try {
2846                                         list( $phpCallback ) = $callback;
2847                                         call_user_func( $phpCallback );
2848                                 } catch ( Exception $ex ) {
2849                                         MWExceptionHandler::logException( $ex );
2850                                         $e = $e ?: $ex;
2851                                 }
2852                         }
2853                 } while ( count( $this->mTrxPreCommitCallbacks ) );
2854
2855                 if ( $e instanceof Exception ) {
2856                         throw $e; // re-throw any first exception
2857                 }
2858         }
2859
2860         /**
2861          * Actually run any "transaction listener" callbacks.
2862          *
2863          * This method should not be used outside of Database/LoadBalancer
2864          *
2865          * @param integer $trigger IDatabase::TRIGGER_* constant
2866          * @throws Exception
2867          * @since 1.20
2868          */
2869         public function runTransactionListenerCallbacks( $trigger ) {
2870                 if ( $this->mTrxEndCallbacksSuppressed ) {
2871                         return;
2872                 }
2873
2874                 /** @var Exception $e */
2875                 $e = null; // first exception
2876
2877                 foreach ( $this->mTrxRecurringCallbacks as $callback ) {
2878                         try {
2879                                 list( $phpCallback ) = $callback;
2880                                 $phpCallback( $trigger, $this );
2881                         } catch ( Exception $ex ) {
2882                                 MWExceptionHandler::logException( $ex );
2883                                 $e = $e ?: $ex;
2884                         }
2885                 }
2886
2887                 if ( $e instanceof Exception ) {
2888                         throw $e; // re-throw any first exception
2889                 }
2890         }
2891
2892         final public function startAtomic( $fname = __METHOD__ ) {
2893                 if ( !$this->mTrxLevel ) {
2894                         $this->begin( $fname, self::TRANSACTION_INTERNAL );
2895                         // If DBO_TRX is set, a series of startAtomic/endAtomic pairs will result
2896                         // in all changes being in one transaction to keep requests transactional.
2897                         if ( !$this->getFlag( DBO_TRX ) ) {
2898                                 $this->mTrxAutomaticAtomic = true;
2899                         }
2900                 }
2901
2902                 $this->mTrxAtomicLevels[] = $fname;
2903         }
2904
2905         final public function endAtomic( $fname = __METHOD__ ) {
2906                 if ( !$this->mTrxLevel ) {
2907                         throw new DBUnexpectedError( $this, "No atomic transaction is open (got $fname)." );
2908                 }
2909                 if ( !$this->mTrxAtomicLevels ||
2910                         array_pop( $this->mTrxAtomicLevels ) !== $fname
2911                 ) {
2912                         throw new DBUnexpectedError( $this, "Invalid atomic section ended (got $fname)." );
2913                 }
2914
2915                 if ( !$this->mTrxAtomicLevels && $this->mTrxAutomaticAtomic ) {
2916                         $this->commit( $fname, self::FLUSHING_INTERNAL );
2917                 }
2918         }
2919
2920         final public function doAtomicSection( $fname, callable $callback ) {
2921                 $this->startAtomic( $fname );
2922                 try {
2923                         $res = call_user_func_array( $callback, [ $this, $fname ] );
2924                 } catch ( Exception $e ) {
2925                         $this->rollback( $fname, self::FLUSHING_INTERNAL );
2926                         throw $e;
2927                 }
2928                 $this->endAtomic( $fname );
2929
2930                 return $res;
2931         }
2932
2933         final public function begin( $fname = __METHOD__, $mode = self::TRANSACTION_EXPLICIT ) {
2934                 // Protect against mismatched atomic section, transaction nesting, and snapshot loss
2935                 if ( $this->mTrxLevel ) {
2936                         if ( $this->mTrxAtomicLevels ) {
2937                                 $levels = implode( ', ', $this->mTrxAtomicLevels );
2938                                 $msg = "$fname: Got explicit BEGIN while atomic section(s) $levels are open.";
2939                                 throw new DBUnexpectedError( $this, $msg );
2940                         } elseif ( !$this->mTrxAutomatic ) {
2941                                 $msg = "$fname: Explicit transaction already active (from {$this->mTrxFname}).";
2942                                 throw new DBUnexpectedError( $this, $msg );
2943                         } else {
2944                                 // @TODO: make this an exception at some point
2945                                 $msg = "$fname: Implicit transaction already active (from {$this->mTrxFname}).";
2946                                 wfLogDBError( $msg );
2947                                 wfWarn( $msg );
2948                                 return; // join the main transaction set
2949                         }
2950                 } elseif ( $this->getFlag( DBO_TRX ) && $mode !== self::TRANSACTION_INTERNAL ) {
2951                         // @TODO: make this an exception at some point
2952                         $msg = "$fname: Implicit transaction expected (DBO_TRX set).";
2953                         wfLogDBError( $msg );
2954                         wfWarn( $msg );
2955                         return; // let any writes be in the main transaction
2956                 }
2957
2958                 // Avoid fatals if close() was called
2959                 $this->assertOpen();
2960
2961                 $this->doBegin( $fname );
2962                 $this->mTrxTimestamp = microtime( true );
2963                 $this->mTrxFname = $fname;
2964                 $this->mTrxDoneWrites = false;
2965                 $this->mTrxAutomatic = ( $mode === self::TRANSACTION_INTERNAL );
2966                 $this->mTrxAutomaticAtomic = false;
2967                 $this->mTrxAtomicLevels = [];
2968                 $this->mTrxShortId = wfRandomString( 12 );
2969                 $this->mTrxWriteDuration = 0.0;
2970                 $this->mTrxWriteQueryCount = 0;
2971                 $this->mTrxWriteAdjDuration = 0.0;
2972                 $this->mTrxWriteAdjQueryCount = 0;
2973                 $this->mTrxWriteCallers = [];
2974                 // First SELECT after BEGIN will establish the snapshot in REPEATABLE-READ.
2975                 // Get an estimate of the replica DB lag before then, treating estimate staleness
2976                 // as lag itself just to be safe
2977                 $status = $this->getApproximateLagStatus();
2978                 $this->mTrxReplicaLag = $status['lag'] + ( microtime( true ) - $status['since'] );
2979         }
2980
2981         /**
2982          * Issues the BEGIN command to the database server.
2983          *
2984          * @see DatabaseBase::begin()
2985          * @param string $fname
2986          */
2987         protected function doBegin( $fname ) {
2988                 $this->query( 'BEGIN', $fname );
2989                 $this->mTrxLevel = 1;
2990         }
2991
2992         final public function commit( $fname = __METHOD__, $flush = '' ) {
2993                 if ( $this->mTrxLevel && $this->mTrxAtomicLevels ) {
2994                         // There are still atomic sections open. This cannot be ignored
2995                         $levels = implode( ', ', $this->mTrxAtomicLevels );
2996                         throw new DBUnexpectedError(
2997                                 $this,
2998                                 "$fname: Got COMMIT while atomic sections $levels are still open."
2999                         );
3000                 }
3001
3002                 if ( $flush === self::FLUSHING_INTERNAL || $flush === self::FLUSHING_ALL_PEERS ) {
3003                         if ( !$this->mTrxLevel ) {
3004                                 return; // nothing to do
3005                         } elseif ( !$this->mTrxAutomatic ) {
3006                                 throw new DBUnexpectedError(
3007                                         $this,
3008                                         "$fname: Flushing an explicit transaction, getting out of sync."
3009                                 );
3010                         }
3011                 } else {
3012                         if ( !$this->mTrxLevel ) {
3013                                 wfWarn( "$fname: No transaction to commit, something got out of sync." );
3014                                 return; // nothing to do
3015                         } elseif ( $this->mTrxAutomatic ) {
3016                                 // @TODO: make this an exception at some point
3017                                 $msg = "$fname: Explicit commit of implicit transaction.";
3018                                 wfLogDBError( $msg );
3019                                 wfWarn( $msg );
3020                                 return; // wait for the main transaction set commit round
3021                         }
3022                 }
3023
3024                 // Avoid fatals if close() was called
3025                 $this->assertOpen();
3026
3027                 $this->runOnTransactionPreCommitCallbacks();
3028                 $writeTime = $this->pendingWriteQueryDuration( self::ESTIMATE_DB_APPLY );
3029                 $this->doCommit( $fname );
3030                 if ( $this->mTrxDoneWrites ) {
3031                         $this->mDoneWrites = microtime( true );
3032                         $this->trxProfiler->transactionWritingOut(
3033                                 $this->mServer, $this->mDBname, $this->mTrxShortId, $writeTime );
3034                 }
3035
3036                 $this->runOnTransactionIdleCallbacks( self::TRIGGER_COMMIT );
3037                 $this->runTransactionListenerCallbacks( self::TRIGGER_COMMIT );
3038         }
3039
3040         /**
3041          * Issues the COMMIT command to the database server.
3042          *
3043          * @see DatabaseBase::commit()
3044          * @param string $fname
3045          */
3046         protected function doCommit( $fname ) {
3047                 if ( $this->mTrxLevel ) {
3048                         $this->query( 'COMMIT', $fname );
3049                         $this->mTrxLevel = 0;
3050                 }
3051         }
3052
3053         final public function rollback( $fname = __METHOD__, $flush = '' ) {
3054                 if ( $flush === self::FLUSHING_INTERNAL || $flush === self::FLUSHING_ALL_PEERS ) {
3055                         if ( !$this->mTrxLevel ) {
3056                                 return; // nothing to do
3057                         }
3058                 } else {
3059                         if ( !$this->mTrxLevel ) {
3060                                 wfWarn( "$fname: No transaction to rollback, something got out of sync." );
3061                                 return; // nothing to do
3062                         } elseif ( $this->getFlag( DBO_TRX ) ) {
3063                                 throw new DBUnexpectedError(
3064                                         $this,
3065                                         "$fname: Expected mass rollback of all peer databases (DBO_TRX set)."
3066                                 );
3067                         }
3068                 }
3069
3070                 // Avoid fatals if close() was called
3071                 $this->assertOpen();
3072
3073                 $this->doRollback( $fname );
3074                 $this->mTrxAtomicLevels = [];
3075                 if ( $this->mTrxDoneWrites ) {
3076                         $this->trxProfiler->transactionWritingOut(
3077                                 $this->mServer, $this->mDBname, $this->mTrxShortId );
3078                 }
3079
3080                 $this->mTrxIdleCallbacks = []; // clear
3081                 $this->mTrxPreCommitCallbacks = []; // clear
3082                 $this->runOnTransactionIdleCallbacks( self::TRIGGER_ROLLBACK );
3083                 $this->runTransactionListenerCallbacks( self::TRIGGER_ROLLBACK );
3084         }
3085
3086         /**
3087          * Issues the ROLLBACK command to the database server.
3088          *
3089          * @see DatabaseBase::rollback()
3090          * @param string $fname
3091          */
3092         protected function doRollback( $fname ) {
3093                 if ( $this->mTrxLevel ) {
3094                         # Disconnects cause rollback anyway, so ignore those errors
3095                         $ignoreErrors = true;
3096                         $this->query( 'ROLLBACK', $fname, $ignoreErrors );
3097                         $this->mTrxLevel = 0;
3098                 }
3099         }
3100
3101         public function flushSnapshot( $fname = __METHOD__ ) {
3102                 if ( $this->writesOrCallbacksPending() || $this->explicitTrxActive() ) {
3103                         // This only flushes transactions to clear snapshots, not to write data
3104                         throw new DBUnexpectedError(
3105                                 $this,
3106                                 "$fname: Cannot COMMIT to clear snapshot because writes are pending."
3107                         );
3108                 }
3109
3110                 $this->commit( $fname, self::FLUSHING_INTERNAL );
3111         }
3112
3113         public function explicitTrxActive() {
3114                 return $this->mTrxLevel && ( $this->mTrxAtomicLevels || !$this->mTrxAutomatic );
3115         }
3116
3117         /**
3118          * Creates a new table with structure copied from existing table
3119          * Note that unlike most database abstraction functions, this function does not
3120          * automatically append database prefix, because it works at a lower
3121          * abstraction level.
3122          * The table names passed to this function shall not be quoted (this
3123          * function calls addIdentifierQuotes when needed).
3124          *
3125          * @param string $oldName Name of table whose structure should be copied
3126          * @param string $newName Name of table to be created
3127          * @param bool $temporary Whether the new table should be temporary
3128          * @param string $fname Calling function name
3129          * @throws MWException
3130          * @return bool True if operation was successful
3131          */
3132         public function duplicateTableStructure( $oldName, $newName, $temporary = false,
3133                 $fname = __METHOD__
3134         ) {
3135                 throw new MWException(
3136                         'DatabaseBase::duplicateTableStructure is not implemented in descendant class' );
3137         }
3138
3139         function listTables( $prefix = null, $fname = __METHOD__ ) {
3140                 throw new MWException( 'DatabaseBase::listTables is not implemented in descendant class' );
3141         }
3142
3143         /**
3144          * Reset the views process cache set by listViews()
3145          * @since 1.22
3146          */
3147         final public function clearViewsCache() {
3148                 $this->allViews = null;
3149         }
3150
3151         /**
3152          * Lists all the VIEWs in the database
3153          *
3154          * For caching purposes the list of all views should be stored in
3155          * $this->allViews. The process cache can be cleared with clearViewsCache()
3156          *
3157          * @param string $prefix Only show VIEWs with this prefix, eg. unit_test_
3158          * @param string $fname Name of calling function
3159          * @throws MWException
3160          * @return array
3161          * @since 1.22
3162          */
3163         public function listViews( $prefix = null, $fname = __METHOD__ ) {
3164                 throw new MWException( 'DatabaseBase::listViews is not implemented in descendant class' );
3165         }
3166
3167         /**
3168          * Differentiates between a TABLE and a VIEW
3169          *
3170          * @param string $name Name of the database-structure to test.
3171          * @throws MWException
3172          * @return bool
3173          * @since 1.22
3174          */
3175         public function isView( $name ) {
3176                 throw new MWException( 'DatabaseBase::isView is not implemented in descendant class' );
3177         }
3178
3179         public function timestamp( $ts = 0 ) {
3180                 return wfTimestamp( TS_MW, $ts );
3181         }
3182
3183         public function timestampOrNull( $ts = null ) {
3184                 if ( is_null( $ts ) ) {
3185                         return null;
3186                 } else {
3187                         return $this->timestamp( $ts );
3188                 }
3189         }
3190
3191         /**
3192          * Take the result from a query, and wrap it in a ResultWrapper if
3193          * necessary. Boolean values are passed through as is, to indicate success
3194          * of write queries or failure.
3195          *
3196          * Once upon a time, DatabaseBase::query() returned a bare MySQL result
3197          * resource, and it was necessary to call this function to convert it to
3198          * a wrapper. Nowadays, raw database objects are never exposed to external
3199          * callers, so this is unnecessary in external code.
3200          *
3201          * @param bool|ResultWrapper|resource|object $result
3202          * @return bool|ResultWrapper
3203          */
3204         protected function resultObject( $result ) {
3205                 if ( !$result ) {
3206                         return false;
3207                 } elseif ( $result instanceof ResultWrapper ) {
3208                         return $result;
3209                 } elseif ( $result === true ) {
3210                         // Successful write query
3211                         return $result;
3212                 } else {
3213                         return new ResultWrapper( $this, $result );
3214                 }
3215         }
3216
3217         public function ping( &$rtt = null ) {
3218                 // Avoid hitting the server if it was hit recently
3219                 if ( $this->isOpen() && ( microtime( true ) - $this->lastPing ) < self::PING_TTL ) {
3220                         if ( !func_num_args() || $this->mRTTEstimate > 0 ) {
3221                                 $rtt = $this->mRTTEstimate;
3222                                 return true; // don't care about $rtt
3223                         }
3224                 }
3225
3226                 // This will reconnect if possible or return false if not
3227                 $this->clearFlag( DBO_TRX, self::REMEMBER_PRIOR );
3228                 $ok = ( $this->query( self::PING_QUERY, __METHOD__, true ) !== false );
3229                 $this->restoreFlags( self::RESTORE_PRIOR );
3230
3231                 if ( $ok ) {
3232                         $rtt = $this->mRTTEstimate;
3233                 }
3234
3235                 return $ok;
3236         }
3237
3238         /**
3239          * @return bool
3240          */
3241         protected function reconnect() {
3242                 $this->closeConnection();
3243                 $this->mOpened = false;
3244                 $this->mConn = false;
3245                 try {
3246                         $this->open( $this->mServer, $this->mUser, $this->mPassword, $this->mDBname );
3247                         $this->lastPing = microtime( true );
3248                         $ok = true;
3249                 } catch ( DBConnectionError $e ) {
3250                         $ok = false;
3251                 }
3252
3253                 return $ok;
3254         }
3255
3256         public function getSessionLagStatus() {
3257                 return $this->getTransactionLagStatus() ?: $this->getApproximateLagStatus();
3258         }
3259
3260         /**
3261          * Get the replica DB lag when the current transaction started
3262          *
3263          * This is useful when transactions might use snapshot isolation
3264          * (e.g. REPEATABLE-READ in innodb), so the "real" lag of that data
3265          * is this lag plus transaction duration. If they don't, it is still
3266          * safe to be pessimistic. This returns null if there is no transaction.
3267          *
3268          * @return array|null ('lag': seconds or false on error, 'since': UNIX timestamp of BEGIN)
3269          * @since 1.27
3270          */
3271         public function getTransactionLagStatus() {
3272                 return $this->mTrxLevel
3273                         ? [ 'lag' => $this->mTrxReplicaLag, 'since' => $this->trxTimestamp() ]
3274                         : null;
3275         }
3276
3277         /**
3278          * Get a replica DB lag estimate for this server
3279          *
3280          * @return array ('lag': seconds or false on error, 'since': UNIX timestamp of estimate)
3281          * @since 1.27
3282          */
3283         public function getApproximateLagStatus() {
3284                 return [
3285                         'lag'   => $this->getLBInfo( 'replica' ) ? $this->getLag() : 0,
3286                         'since' => microtime( true )
3287                 ];
3288         }
3289
3290         /**
3291          * Merge the result of getSessionLagStatus() for several DBs
3292          * using the most pessimistic values to estimate the lag of
3293          * any data derived from them in combination
3294          *
3295          * This is information is useful for caching modules
3296          *
3297          * @see WANObjectCache::set()
3298          * @see WANObjectCache::getWithSetCallback()
3299          *
3300          * @param IDatabase $db1
3301          * @param IDatabase ...
3302          * @return array Map of values:
3303          *   - lag: highest lag of any of the DBs or false on error (e.g. replication stopped)
3304          *   - since: oldest UNIX timestamp of any of the DB lag estimates
3305          *   - pending: whether any of the DBs have uncommitted changes
3306          * @since 1.27
3307          */
3308         public static function getCacheSetOptions( IDatabase $db1 ) {
3309                 $res = [ 'lag' => 0, 'since' => INF, 'pending' => false ];
3310                 foreach ( func_get_args() as $db ) {
3311                         /** @var IDatabase $db */
3312                         $status = $db->getSessionLagStatus();
3313                         if ( $status['lag'] === false ) {
3314                                 $res['lag'] = false;
3315                         } elseif ( $res['lag'] !== false ) {
3316                                 $res['lag'] = max( $res['lag'], $status['lag'] );
3317                         }
3318                         $res['since'] = min( $res['since'], $status['since'] );
3319                         $res['pending'] = $res['pending'] ?: $db->writesPending();
3320                 }
3321
3322                 return $res;
3323         }
3324
3325         public function getLag() {
3326                 return 0;
3327         }
3328
3329         function maxListLen() {
3330                 return 0;
3331         }
3332
3333         public function encodeBlob( $b ) {
3334                 return $b;
3335         }
3336
3337         public function decodeBlob( $b ) {
3338                 if ( $b instanceof Blob ) {
3339                         $b = $b->fetch();
3340                 }
3341                 return $b;
3342         }
3343
3344         public function setSessionOptions( array $options ) {
3345         }
3346
3347         /**
3348          * Read and execute SQL commands from a file.
3349          *
3350          * Returns true on success, error string or exception on failure (depending
3351          * on object's error ignore settings).
3352          *
3353          * @param string $filename File name to open
3354          * @param bool|callable $lineCallback Optional function called before reading each line
3355          * @param bool|callable $resultCallback Optional function called for each MySQL result
3356          * @param bool|string $fname Calling function name or false if name should be
3357          *   generated dynamically using $filename
3358          * @param bool|callable $inputCallback Optional function called for each
3359          *   complete line sent
3360          * @throws Exception|MWException
3361          * @return bool|string
3362          */
3363         public function sourceFile(
3364                 $filename, $lineCallback = false, $resultCallback = false, $fname = false, $inputCallback = false
3365         ) {
3366                 MediaWiki\suppressWarnings();
3367                 $fp = fopen( $filename, 'r' );
3368                 MediaWiki\restoreWarnings();
3369
3370                 if ( false === $fp ) {
3371                         throw new MWException( "Could not open \"{$filename}\".\n" );
3372                 }
3373
3374                 if ( !$fname ) {
3375                         $fname = __METHOD__ . "( $filename )";
3376                 }
3377
3378                 try {
3379                         $error = $this->sourceStream( $fp, $lineCallback, $resultCallback, $fname, $inputCallback );
3380                 } catch ( Exception $e ) {
3381                         fclose( $fp );
3382                         throw $e;
3383                 }
3384
3385                 fclose( $fp );
3386
3387                 return $error;
3388         }
3389
3390         /**
3391          * Get the full path of a patch file. Originally based on archive()
3392          * from updaters.inc. Keep in mind this always returns a patch, as
3393          * it fails back to MySQL if no DB-specific patch can be found
3394          *
3395          * @param string $patch The name of the patch, like patch-something.sql
3396          * @return string Full path to patch file
3397          */
3398         public function patchPath( $patch ) {
3399                 global $IP;
3400
3401                 $dbType = $this->getType();
3402                 if ( file_exists( "$IP/maintenance/$dbType/archives/$patch" ) ) {
3403                         return "$IP/maintenance/$dbType/archives/$patch";
3404                 } else {
3405                         return "$IP/maintenance/archives/$patch";
3406                 }
3407         }
3408
3409         public function setSchemaVars( $vars ) {
3410                 $this->mSchemaVars = $vars;
3411         }
3412
3413         /**
3414          * Read and execute commands from an open file handle.
3415          *
3416          * Returns true on success, error string or exception on failure (depending
3417          * on object's error ignore settings).
3418          *
3419          * @param resource $fp File handle
3420          * @param bool|callable $lineCallback Optional function called before reading each query
3421          * @param bool|callable $resultCallback Optional function called for each MySQL result
3422          * @param string $fname Calling function name
3423          * @param bool|callable $inputCallback Optional function called for each complete query sent
3424          * @return bool|string
3425          */
3426         public function sourceStream( $fp, $lineCallback = false, $resultCallback = false,
3427                 $fname = __METHOD__, $inputCallback = false
3428         ) {
3429                 $cmd = '';
3430
3431                 while ( !feof( $fp ) ) {
3432                         if ( $lineCallback ) {
3433                                 call_user_func( $lineCallback );
3434                         }
3435
3436                         $line = trim( fgets( $fp ) );
3437
3438                         if ( $line == '' ) {
3439                                 continue;
3440                         }
3441
3442                         if ( '-' == $line[0] && '-' == $line[1] ) {
3443                                 continue;
3444                         }
3445
3446                         if ( $cmd != '' ) {
3447                                 $cmd .= ' ';
3448                         }
3449
3450                         $done = $this->streamStatementEnd( $cmd, $line );
3451
3452                         $cmd .= "$line\n";
3453
3454                         if ( $done || feof( $fp ) ) {
3455                                 $cmd = $this->replaceVars( $cmd );
3456
3457                                 if ( ( $inputCallback && call_user_func( $inputCallback, $cmd ) ) || !$inputCallback ) {
3458                                         $res = $this->query( $cmd, $fname );
3459
3460                                         if ( $resultCallback ) {
3461                                                 call_user_func( $resultCallback, $res, $this );
3462                                         }
3463
3464                                         if ( false === $res ) {
3465                                                 $err = $this->lastError();
3466
3467                                                 return "Query \"{$cmd}\" failed with error code \"$err\".\n";
3468                                         }
3469                                 }
3470                                 $cmd = '';
3471                         }
3472                 }
3473
3474                 return true;
3475         }
3476
3477         /**
3478          * Called by sourceStream() to check if we've reached a statement end
3479          *
3480          * @param string $sql SQL assembled so far
3481          * @param string $newLine New line about to be added to $sql
3482          * @return bool Whether $newLine contains end of the statement
3483          */
3484         public function streamStatementEnd( &$sql, &$newLine ) {
3485                 if ( $this->delimiter ) {
3486                         $prev = $newLine;
3487                         $newLine = preg_replace( '/' . preg_quote( $this->delimiter, '/' ) . '$/', '', $newLine );
3488                         if ( $newLine != $prev ) {
3489                                 return true;
3490                         }
3491                 }
3492
3493                 return false;
3494         }
3495
3496         /**
3497          * Database independent variable replacement. Replaces a set of variables
3498          * in an SQL statement with their contents as given by $this->getSchemaVars().
3499          *
3500          * Supports '{$var}' `{$var}` and / *$var* / (without the spaces) style variables.
3501          *
3502          * - '{$var}' should be used for text and is passed through the database's
3503          *   addQuotes method.
3504          * - `{$var}` should be used for identifiers (e.g. table and database names).
3505          *   It is passed through the database's addIdentifierQuotes method which
3506          *   can be overridden if the database uses something other than backticks.
3507          * - / *_* / or / *$wgDBprefix* / passes the name that follows through the
3508          *   database's tableName method.
3509          * - / *i* / passes the name that follows through the database's indexName method.
3510          * - In all other cases, / *$var* / is left unencoded. Except for table options,
3511          *   its use should be avoided. In 1.24 and older, string encoding was applied.
3512          *
3513          * @param string $ins SQL statement to replace variables in
3514          * @return string The new SQL statement with variables replaced
3515          */
3516         protected function replaceVars( $ins ) {
3517                 $vars = $this->getSchemaVars();
3518                 return preg_replace_callback(
3519                         '!
3520                                 /\* (\$wgDBprefix|[_i]) \*/ (\w*) | # 1-2. tableName, indexName
3521                                 \'\{\$ (\w+) }\'                  | # 3. addQuotes
3522                                 `\{\$ (\w+) }`                    | # 4. addIdentifierQuotes
3523                                 /\*\$ (\w+) \*/                     # 5. leave unencoded
3524                         !x',
3525                         function ( $m ) use ( $vars ) {
3526                                 // Note: Because of <https://bugs.php.net/bug.php?id=51881>,
3527                                 // check for both nonexistent keys *and* the empty string.
3528                                 if ( isset( $m[1] ) && $m[1] !== '' ) {
3529                                         if ( $m[1] === 'i' ) {
3530                                                 return $this->indexName( $m[2] );
3531                                         } else {
3532                                                 return $this->tableName( $m[2] );
3533                                         }
3534                                 } elseif ( isset( $m[3] ) && $m[3] !== '' && array_key_exists( $m[3], $vars ) ) {
3535                                         return $this->addQuotes( $vars[$m[3]] );
3536                                 } elseif ( isset( $m[4] ) && $m[4] !== '' && array_key_exists( $m[4], $vars ) ) {
3537                                         return $this->addIdentifierQuotes( $vars[$m[4]] );
3538                                 } elseif ( isset( $m[5] ) && $m[5] !== '' && array_key_exists( $m[5], $vars ) ) {
3539                                         return $vars[$m[5]];
3540                                 } else {
3541                                         return $m[0];
3542                                 }
3543                         },
3544                         $ins
3545                 );
3546         }
3547
3548         /**
3549          * Get schema variables. If none have been set via setSchemaVars(), then
3550          * use some defaults from the current object.
3551          *
3552          * @return array
3553          */
3554         protected function getSchemaVars() {
3555                 if ( $this->mSchemaVars ) {
3556                         return $this->mSchemaVars;
3557                 } else {
3558                         return $this->getDefaultSchemaVars();
3559                 }
3560         }
3561
3562         /**
3563          * Get schema variables to use if none have been set via setSchemaVars().
3564          *
3565          * Override this in derived classes to provide variables for tables.sql
3566          * and SQL patch files.
3567          *
3568          * @return array
3569          */
3570         protected function getDefaultSchemaVars() {
3571                 return [];
3572         }
3573
3574         public function lockIsFree( $lockName, $method ) {
3575                 return true;
3576         }
3577
3578         public function lock( $lockName, $method, $timeout = 5 ) {
3579                 $this->mNamedLocksHeld[$lockName] = 1;
3580
3581                 return true;
3582         }
3583
3584         public function unlock( $lockName, $method ) {
3585                 unset( $this->mNamedLocksHeld[$lockName] );
3586
3587                 return true;
3588         }
3589
3590         public function getScopedLockAndFlush( $lockKey, $fname, $timeout ) {
3591                 if ( $this->writesOrCallbacksPending() ) {
3592                         // This only flushes transactions to clear snapshots, not to write data
3593                         throw new DBUnexpectedError(
3594                                 $this,
3595                                 "$fname: Cannot COMMIT to clear snapshot because writes are pending."
3596                         );
3597                 }
3598
3599                 if ( !$this->lock( $lockKey, $fname, $timeout ) ) {
3600                         return null;
3601                 }
3602
3603                 $unlocker = new ScopedCallback( function () use ( $lockKey, $fname ) {
3604                         if ( $this->trxLevel() ) {
3605                                 // There is a good chance an exception was thrown, causing any early return
3606                                 // from the caller. Let any error handler get a chance to issue rollback().
3607                                 // If there isn't one, let the error bubble up and trigger server-side rollback.
3608                                 $this->onTransactionResolution( function () use ( $lockKey, $fname ) {
3609                                         $this->unlock( $lockKey, $fname );
3610                                 } );
3611                         } else {
3612                                 $this->unlock( $lockKey, $fname );
3613                         }
3614                 } );
3615
3616                 $this->commit( __METHOD__, self::FLUSHING_INTERNAL );
3617
3618                 return $unlocker;
3619         }
3620
3621         public function namedLocksEnqueue() {
3622                 return false;
3623         }
3624
3625         /**
3626          * Lock specific tables
3627          *
3628          * @param array $read Array of tables to lock for read access
3629          * @param array $write Array of tables to lock for write access
3630          * @param string $method Name of caller
3631          * @param bool $lowPriority Whether to indicate writes to be LOW PRIORITY
3632          * @return bool
3633          */
3634         public function lockTables( $read, $write, $method, $lowPriority = true ) {
3635                 return true;
3636         }
3637
3638         /**
3639          * Unlock specific tables
3640          *
3641          * @param string $method The caller
3642          * @return bool
3643          */
3644         public function unlockTables( $method ) {
3645                 return true;
3646         }
3647
3648         /**
3649          * Delete a table
3650          * @param string $tableName
3651          * @param string $fName
3652          * @return bool|ResultWrapper
3653          * @since 1.18
3654          */
3655         public function dropTable( $tableName, $fName = __METHOD__ ) {
3656                 if ( !$this->tableExists( $tableName, $fName ) ) {
3657                         return false;
3658                 }
3659                 $sql = "DROP TABLE " . $this->tableName( $tableName );
3660                 if ( $this->cascadingDeletes() ) {
3661                         $sql .= " CASCADE";
3662                 }
3663
3664                 return $this->query( $sql, $fName );
3665         }
3666
3667         /**
3668          * Get search engine class. All subclasses of this need to implement this
3669          * if they wish to use searching.
3670          *
3671          * @return string
3672          */
3673         public function getSearchEngine() {
3674                 return 'SearchEngineDummy';
3675         }
3676
3677         public function getInfinity() {
3678                 return 'infinity';
3679         }
3680
3681         public function encodeExpiry( $expiry ) {
3682                 return ( $expiry == '' || $expiry == 'infinity' || $expiry == $this->getInfinity() )
3683                         ? $this->getInfinity()
3684                         : $this->timestamp( $expiry );
3685         }
3686
3687         public function decodeExpiry( $expiry, $format = TS_MW ) {
3688                 return ( $expiry == '' || $expiry == 'infinity' || $expiry == $this->getInfinity() )
3689                         ? 'infinity'
3690                         : wfTimestamp( $format, $expiry );
3691         }
3692
3693         public function setBigSelects( $value = true ) {
3694                 // no-op
3695         }
3696
3697         public function isReadOnly() {
3698                 return ( $this->getReadOnlyReason() !== false );
3699         }
3700
3701         /**
3702          * @return string|bool Reason this DB is read-only or false if it is not
3703          */
3704         protected function getReadOnlyReason() {
3705                 $reason = $this->getLBInfo( 'readOnlyReason' );
3706
3707                 return is_string( $reason ) ? $reason : false;
3708         }
3709
3710         /**
3711          * @since 1.19
3712          * @return string
3713          */
3714         public function __toString() {
3715                 return (string)$this->mConn;
3716         }
3717
3718         /**
3719          * Run a few simple sanity checks
3720          */
3721         public function __destruct() {
3722                 if ( $this->mTrxLevel && $this->mTrxDoneWrites ) {
3723                         trigger_error( "Uncommitted DB writes (transaction from {$this->mTrxFname})." );
3724                 }
3725                 $danglingCallbacks = array_merge(
3726                         $this->mTrxIdleCallbacks,
3727                         $this->mTrxPreCommitCallbacks,
3728                         $this->mTrxEndCallbacks
3729                 );
3730                 if ( $danglingCallbacks ) {
3731                         $callers = [];
3732                         foreach ( $danglingCallbacks as $callbackInfo ) {
3733                                 $callers[] = $callbackInfo[1];
3734                         }
3735                         $callers = implode( ', ', $callers );
3736                         trigger_error( "DB transaction callbacks still pending (from $callers)." );
3737                 }
3738         }
3739 }
3740
3741 /**
3742  * @since 1.27
3743  */
3744 abstract class Database extends DatabaseBase {
3745         // B/C until nothing type hints for DatabaseBase
3746         // @TODO: finish renaming DatabaseBase => Database
3747 }