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