includes/db/Database.php

   1 <?php
   2
   3 /**
   4  * @defgroup Database Database
   5  *
   6  * This file deals with database interface functions
   7  * and query specifics/optimisations.
   8  *
   9  * This program is free software; you can redistribute it and/or modify
  10  * it under the terms of the GNU General Public License as published by
  11  * the Free Software Foundation; either version 2 of the License, or
  12  * (at your option) any later version.
  13  *
  14  * This program is distributed in the hope that it will be useful,
  15  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  16  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
  17  * GNU General Public License for more details.
  18  *
  19  * You should have received a copy of the GNU General Public License along
  20  * with this program; if not, write to the Free Software Foundation, Inc.,
  21  * 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
  22  * http://www.gnu.org/copyleft/gpl.html
  23  *
  24  * @file
  25  * @ingroup Database
  26  */
  27
  28 /**
  29  * Database abstraction object
  30  * @ingroup Database
  31  */
  32 abstract class DatabaseBase implements IDatabase {
  33         /** Number of times to re-try an operation in case of deadlock */
  34         const DEADLOCK_TRIES = 4;
  35         /** Minimum time to wait before retry, in microseconds */
  36         const DEADLOCK_DELAY_MIN = 500000;
  37         /** Maximum time to wait before retry */
  38         const DEADLOCK_DELAY_MAX = 1500000;
  39
  40         /** How long before it is worth doing a dummy query to test the connection */
  41         const PING_TTL = 1.0;
  42         const PING_QUERY = 'SELECT 1 AS ping';
  43
  44         const TINY_WRITE_SEC = .010;
  45         const SLOW_WRITE_SEC = .500;
  46         const SMALL_WRITE_ROWS = 100;
  47
  48         /** @var string SQL query */
  49         protected $mLastQuery = '';
  50         /** @var bool */
  51         protected $mDoneWrites = false;
  52         /** @var string|bool */
  53         protected $mPHPError = false;
  54         /** @var string */
  55         protected $mServer;
  56         /** @var string */
  57         protected $mUser;
  58         /** @var string */
  59         protected $mPassword;
  60         /** @var string */
  61         protected $mDBname;
  62         /** @var bool */
  63         protected $cliMode;
  64
  65         /** @var BagOStuff APC cache */
  66         protected $srvCache;
  67
  68         /** @var resource Database connection */
  69         protected $mConn = null;
  70         /** @var bool */
  71         protected $mOpened = false;
  72
  73         /** @var array[] List of (callable, method name) */
  74         protected $mTrxIdleCallbacks = [];
  75         /** @var array[] List of (callable, method name) */
  76         protected $mTrxPreCommitCallbacks = [];
  77         /** @var array[] List of (callable, method name) */
  78         protected $mTrxEndCallbacks = [];
  79         /** @var array[] Map of (name => (callable, method name)) */
  80         protected $mTrxRecurringCallbacks = [];
  81         /** @var bool Whether to suppress triggering of transaction end callbacks */
  82         protected $mTrxEndCallbacksSuppressed = false;
  83
  84         /** @var string */
  85         protected $mTablePrefix;
  86         /** @var string */
  87         protected $mSchema;
  88         /** @var integer */
  89         protected $mFlags;
  90         /** @var bool */
  91         protected $mForeign;
  92         /** @var array */
  93         protected $mLBInfo = [];
  94         /** @var bool|null */
  95         protected $mDefaultBigSelects = null;
  96         /** @var array|bool */
  97         protected $mSchemaVars = false;
  98         /** @var array */
  99         protected $mSessionVars = [];
 100         /** @var array|null */
 101         protected $preparedArgs;
 102         /** @var string|bool|null Stashed value of html_errors INI setting */
 103         protected $htmlErrors;
 104         /** @var string */
 105         protected $delimiter = ';';
 106
 107         /**
 108          * Either 1 if a transaction is active or 0 otherwise.
 109          * The other Trx fields may not be meaningfull if this is 0.
 110          *
 111          * @var int
 112          */
 113         protected $mTrxLevel = 0;
 114         /**
 115          * Either a short hexidecimal string if a transaction is active or ""
 116          *
 117          * @var string
 118          * @see DatabaseBase::mTrxLevel
 119          */
 120         protected $mTrxShortId = '';
 121         /**
 122          * The UNIX time that the transaction started. Callers can assume that if
 123          * snapshot isolation is used, then the data is *at least* up to date to that
 124          * point (possibly more up-to-date since the first SELECT defines the snapshot).
 125          *
 126          * @var float|null
 127          * @see DatabaseBase::mTrxLevel
 128          */
 129         private $mTrxTimestamp = null;
 130         /** @var float Lag estimate at the time of BEGIN */
 131         private $mTrxSlaveLag = null;
 132         /**
 133          * Remembers the function name given for starting the most recent transaction via begin().
 134          * Used to provide additional context for error reporting.
 135          *
 136          * @var string
 137          * @see DatabaseBase::mTrxLevel
 138          */
 139         private $mTrxFname = null;
 140         /**
 141          * Record if possible write queries were done in the last transaction started
 142          *
 143          * @var bool
 144          * @see DatabaseBase::mTrxLevel
 145          */
 146         private $mTrxDoneWrites = false;
 147         /**
 148          * Record if the current transaction was started implicitly due to DBO_TRX being set.
 149          *
 150          * @var bool
 151          * @see DatabaseBase::mTrxLevel
 152          */
 153         private $mTrxAutomatic = false;
 154         /**
 155          * Array of levels of atomicity within transactions
 156          *
 157          * @var array
 158          */
 159         private $mTrxAtomicLevels = [];
 160         /**
 161          * Record if the current transaction was started implicitly by DatabaseBase::startAtomic
 162          *
 163          * @var bool
 164          */
 165         private $mTrxAutomaticAtomic = false;
 166         /**
 167          * Track the write query callers of the current transaction
 168          *
 169          * @var string[]
 170          */
 171         private $mTrxWriteCallers = [];
 172         /**
 173          * @var float Seconds spent in write queries for the current transaction
 174          */
 175         private $mTrxWriteDuration = 0.0;
 176         /**
 177          * @var integer Number of write queries for the current transaction
 178          */
 179         private $mTrxWriteQueryCount = 0;
 180         /**
 181          * @var float Like mTrxWriteQueryCount but excludes lock-bound, easy to replicate, queries
 182          */
 183         private $mTrxWriteAdjDuration = 0.0;
 184         /**
 185          * @var integer Number of write queries counted in mTrxWriteAdjDuration
 186          */
 187         private $mTrxWriteAdjQueryCount = 0;
 188         /**
 189          * @var float RTT time estimate
 190          */
 191         private $mRTTEstimate = 0.0;
 192
 193         /** @var array Map of (name => 1) for locks obtained via lock() */
 194         private $mNamedLocksHeld = [];
 195
 196         /** @var IDatabase|null Lazy handle to the master DB this server replicates from */
 197         private $lazyMasterHandle;
 198
 199         /**
 200          * @since 1.21
 201          * @var resource File handle for upgrade
 202          */
 203         protected $fileHandle = null;
 204
 205         /**
 206          * @since 1.22
 207          * @var string[] Process cache of VIEWs names in the database
 208          */
 209         protected $allViews = null;
 210
 211         /** @var float UNIX timestamp */
 212         protected $lastPing = 0.0;
 213
 214         /** @var int[] Prior mFlags values */
 215         private $priorFlags = [];
 216
 217         /** @var Profiler */
 218         protected $profiler;
 219         /** @var TransactionProfiler */
 220         protected $trxProfiler;
 221
 222         public function getServerInfo() {
 223                 return $this->getServerVersion();
 224         }
 225
 226         /**
 227          * @return string Command delimiter used by this database engine
 228          */
 229         public function getDelimiter() {
 230                 return $this->delimiter;
 231         }
 232
 233         /**
 234          * Boolean, controls output of large amounts of debug information.
 235          * @param bool|null $debug
 236          *   - true to enable debugging
 237          *   - false to disable debugging
 238          *   - omitted or null to do nothing
 239          *
 240          * @return bool|null Previous value of the flag
 241          */
 242         public function debug( $debug = null ) {
 243                 return wfSetBit( $this->mFlags, DBO_DEBUG, $debug );
 244         }
 245
 246         public function bufferResults( $buffer = null ) {
 247                 if ( is_null( $buffer ) ) {
 248                         return !(bool)( $this->mFlags & DBO_NOBUFFER );
 249                 } else {
 250                         return !wfSetBit( $this->mFlags, DBO_NOBUFFER, !$buffer );
 251                 }
 252         }
 253
 254         /**
 255          * Turns on (false) or off (true) the automatic generation and sending
 256          * of a "we're sorry, but there has been a database error" page on
 257          * database errors. Default is on (false). When turned off, the
 258          * code should use lastErrno() and lastError() to handle the
 259          * situation as appropriate.
 260          *
 261          * Do not use this function outside of the Database classes.
 262          *
 263          * @param null|bool $ignoreErrors
 264          * @return bool The previous value of the flag.
 265          */
 266         protected function ignoreErrors( $ignoreErrors = null ) {
 267                 return wfSetBit( $this->mFlags, DBO_IGNORE, $ignoreErrors );
 268         }
 269
 270         public function trxLevel() {
 271                 return $this->mTrxLevel;
 272         }
 273
 274         public function trxTimestamp() {
 275                 return $this->mTrxLevel ? $this->mTrxTimestamp : null;
 276         }
 277
 278         public function tablePrefix( $prefix = null ) {
 279                 return wfSetVar( $this->mTablePrefix, $prefix );
 280         }
 281
 282         public function dbSchema( $schema = null ) {
 283                 return wfSetVar( $this->mSchema, $schema );
 284         }
 285
 286         /**
 287          * Set the filehandle to copy write statements to.
 288          *
 289          * @param resource $fh File handle
 290          */
 291         public function setFileHandle( $fh ) {
 292                 $this->fileHandle = $fh;
 293         }
 294
 295         public function getLBInfo( $name = null ) {
 296                 if ( is_null( $name ) ) {
 297                         return $this->mLBInfo;
 298                 } else {
 299                         if ( array_key_exists( $name, $this->mLBInfo ) ) {
 300                                 return $this->mLBInfo[$name];
 301                         } else {
 302                                 return null;
 303                         }
 304                 }
 305         }
 306
 307         public function setLBInfo( $name, $value = null ) {
 308                 if ( is_null( $value ) ) {
 309                         $this->mLBInfo = $name;
 310                 } else {
 311                         $this->mLBInfo[$name] = $value;
 312                 }
 313         }
 314
 315         /**
 316          * Set a lazy-connecting DB handle to the master DB (for replication status purposes)
 317          *
 318          * @param IDatabase $conn
 319          * @since 1.27
 320          */
 321         public function setLazyMasterHandle( IDatabase $conn ) {
 322                 $this->lazyMasterHandle = $conn;
 323         }
 324
 325         /**
 326          * @return IDatabase|null
 327          * @see setLazyMasterHandle()
 328          * @since 1.27
 329          */
 330         public function getLazyMasterHandle() {
 331                 return $this->lazyMasterHandle;
 332         }
 333
 334         /**
 335          * @return TransactionProfiler
 336          */
 337         protected function getTransactionProfiler() {
 338                 return $this->trxProfiler;
 339         }
 340
 341         /**
 342          * @param TransactionProfiler $profiler
 343          * @since 1.27
 344          */
 345         public function setTransactionProfiler( TransactionProfiler $profiler ) {
 346                 $this->trxProfiler = $profiler;
 347         }
 348
 349         /**
 350          * Returns true if this database supports (and uses) cascading deletes
 351          *
 352          * @return bool
 353          */
 354         public function cascadingDeletes() {
 355                 return false;
 356         }
 357
 358         /**
 359          * Returns true if this database supports (and uses) triggers (e.g. on the page table)
 360          *
 361          * @return bool
 362          */
 363         public function cleanupTriggers() {
 364                 return false;
 365         }
 366
 367         /**
 368          * Returns true if this database is strict about what can be put into an IP field.
 369          * Specifically, it uses a NULL value instead of an empty string.
 370          *
 371          * @return bool
 372          */
 373         public function strictIPs() {
 374                 return false;
 375         }
 376
 377         /**
 378          * Returns true if this database uses timestamps rather than integers
 379          *
 380          * @return bool
 381          */
 382         public function realTimestamps() {
 383                 return false;
 384         }
 385
 386         public function implicitGroupby() {
 387                 return true;
 388         }
 389
 390         public function implicitOrderby() {
 391                 return true;
 392         }
 393
 394         /**
 395          * Returns true if this database can do a native search on IP columns
 396          * e.g. this works as expected: .. WHERE rc_ip = '127.42.12.102/32';
 397          *
 398          * @return bool
 399          */
 400         public function searchableIPs() {
 401                 return false;
 402         }
 403
 404         /**
 405          * Returns true if this database can use functional indexes
 406          *
 407          * @return bool
 408          */
 409         public function functionalIndexes() {
 410                 return false;
 411         }
 412
 413         public function lastQuery() {
 414                 return $this->mLastQuery;
 415         }
 416
 417         public function doneWrites() {
 418                 return (bool)$this->mDoneWrites;
 419         }
 420
 421         public function lastDoneWrites() {
 422                 return $this->mDoneWrites ?: false;
 423         }
 424
 425         public function writesPending() {
 426                 return $this->mTrxLevel && $this->mTrxDoneWrites;
 427         }
 428
 429         public function writesOrCallbacksPending() {
 430                 return $this->mTrxLevel && (
 431                         $this->mTrxDoneWrites || $this->mTrxIdleCallbacks || $this->mTrxPreCommitCallbacks
 432                 );
 433         }
 434
 435         public function pendingWriteQueryDuration( $type = self::ESTIMATE_TOTAL ) {
 436                 if ( !$this->mTrxLevel ) {
 437                         return false;
 438                 } elseif ( !$this->mTrxDoneWrites ) {
 439                         return 0.0;
 440                 }
 441
 442                 switch ( $type ) {
 443                         case self::ESTIMATE_DB_APPLY:
 444                                 $this->ping( $rtt );
 445                                 $rttAdjTotal = $this->mTrxWriteAdjQueryCount * $rtt;
 446                                 $applyTime = max( $this->mTrxWriteAdjDuration - $rttAdjTotal, 0 );
 447                                 // For omitted queries, make them count as something at least
 448                                 $omitted = $this->mTrxWriteQueryCount - $this->mTrxWriteAdjQueryCount;
 449                                 $applyTime += self::TINY_WRITE_SEC * $omitted;
 450
 451                                 return $applyTime;
 452                         default: // everything
 453                                 return $this->mTrxWriteDuration;
 454                 }
 455         }
 456
 457         public function pendingWriteCallers() {
 458                 return $this->mTrxLevel ? $this->mTrxWriteCallers : [];
 459         }
 460
 461         public function isOpen() {
 462                 return $this->mOpened;
 463         }
 464
 465         public function setFlag( $flag, $remember = self::REMEMBER_NOTHING ) {
 466                 if ( $remember === self::REMEMBER_PRIOR ) {
 467                         array_push( $this->priorFlags, $this->mFlags );
 468                 }
 469                 $this->mFlags |= $flag;
 470         }
 471
 472         public function clearFlag( $flag, $remember = self::REMEMBER_NOTHING ) {
 473                 if ( $remember === self::REMEMBER_PRIOR ) {
 474                         array_push( $this->priorFlags, $this->mFlags );
 475                 }
 476                 $this->mFlags &= ~$flag;
 477         }
 478
 479         public function restoreFlags( $state = self::RESTORE_PRIOR ) {
 480                 if ( !$this->priorFlags ) {
 481                         return;
 482                 }
 483
 484                 if ( $state === self::RESTORE_INITIAL ) {
 485                         $this->mFlags = reset( $this->priorFlags );
 486                         $this->priorFlags = [];
 487                 } else {
 488                         $this->mFlags = array_pop( $this->priorFlags );
 489                 }
 490         }
 491
 492         public function getFlag( $flag ) {
 493                 return !!( $this->mFlags & $flag );
 494         }
 495
 496         public function getProperty( $name ) {
 497                 return $this->$name;
 498         }
 499
 500         public function getWikiID() {
 501                 if ( $this->mTablePrefix ) {
 502                         return "{$this->mDBname}-{$this->mTablePrefix}";
 503                 } else {
 504                         return $this->mDBname;
 505                 }
 506         }
 507
 508         /**
 509          * Return a path to the DBMS-specific SQL file if it exists,
 510          * otherwise default SQL file
 511          *
 512          * @param string $filename
 513          * @return string
 514          */
 515         private function getSqlFilePath( $filename ) {
 516                 global $IP;
 517                 $dbmsSpecificFilePath = "$IP/maintenance/" . $this->getType() . "/$filename";
 518                 if ( file_exists( $dbmsSpecificFilePath ) ) {
 519                         return $dbmsSpecificFilePath;
 520                 } else {
 521                         return "$IP/maintenance/$filename";
 522                 }
 523         }
 524
 525         /**
 526          * Return a path to the DBMS-specific schema file,
 527          * otherwise default to tables.sql
 528          *
 529          * @return string
 530          */
 531         public function getSchemaPath() {
 532                 return $this->getSqlFilePath( 'tables.sql' );
 533         }
 534
 535         /**
 536          * Return a path to the DBMS-specific update key file,
 537          * otherwise default to update-keys.sql
 538          *
 539          * @return string
 540          */
 541         public function getUpdateKeysPath() {
 542                 return $this->getSqlFilePath( 'update-keys.sql' );
 543         }
 544
 545         /**
 546          * Get information about an index into an object
 547          * @param string $table Table name
 548          * @param string $index Index name
 549          * @param string $fname Calling function name
 550          * @return mixed Database-specific index description class or false if the index does not exist
 551          */
 552         abstract function indexInfo( $table, $index, $fname = __METHOD__ );
 553
 554         /**
 555          * Wrapper for addslashes()
 556          *
 557          * @param string $s String to be slashed.
 558          * @return string Slashed string.
 559          */
 560         abstract function strencode( $s );
 561
 562         /**
 563          * Constructor.
 564          *
 565          * FIXME: It is possible to construct a Database object with no associated
 566          * connection object, by specifying no parameters to __construct(). This
 567          * feature is deprecated and should be removed.
 568          *
 569          * DatabaseBase subclasses should not be constructed directly in external
 570          * code. DatabaseBase::factory() should be used instead.
 571          *
 572          * @param array $params Parameters passed from DatabaseBase::factory()
 573          */
 574         function __construct( array $params ) {
 575                 global $wgDBprefix, $wgDBmwschema;
 576
 577                 $this->srvCache = ObjectCache::getLocalServerInstance( 'hash' );
 578
 579                 $server = $params['host'];
 580                 $user = $params['user'];
 581                 $password = $params['password'];
 582                 $dbName = $params['dbname'];
 583                 $flags = $params['flags'];
 584                 $tablePrefix = $params['tablePrefix'];
 585                 $schema = $params['schema'];
 586                 $foreign = $params['foreign'];
 587
 588                 $this->cliMode = isset( $params['cliMode'] )
 589                         ? $params['cliMode']
 590                         : ( PHP_SAPI === 'cli' );
 591
 592                 $this->mFlags = $flags;
 593                 if ( $this->mFlags & DBO_DEFAULT ) {
 594                         if ( $this->cliMode ) {
 595                                 $this->mFlags &= ~DBO_TRX;
 596                         } else {
 597                                 $this->mFlags |= DBO_TRX;
 598                         }
 599                 }
 600
 601                 $this->mSessionVars = $params['variables'];
 602
 603                 /** Get the default table prefix*/
 604                 if ( $tablePrefix === 'get from global' ) {
 605                         $this->mTablePrefix = $wgDBprefix;
 606                 } else {
 607                         $this->mTablePrefix = $tablePrefix;
 608                 }
 609
 610                 /** Get the database schema*/
 611                 if ( $schema === 'get from global' ) {
 612                         $this->mSchema = $wgDBmwschema;
 613                 } else {
 614                         $this->mSchema = $schema;
 615                 }
 616
 617                 $this->mForeign = $foreign;
 618
 619                 $this->profiler = isset( $params['profiler'] )
 620                         ? $params['profiler']
 621                         : Profiler::instance(); // @TODO: remove global state
 622                 $this->trxProfiler = isset( $params['trxProfiler'] )
 623                         ? $params['trxProfiler']
 624                         : new TransactionProfiler();
 625
 626                 if ( $user ) {
 627                         $this->open( $server, $user, $password, $dbName );
 628                 }
 629
 630         }
 631
 632         /**
 633          * Called by serialize. Throw an exception when DB connection is serialized.
 634          * This causes problems on some database engines because the connection is
 635          * not restored on unserialize.
 636          */
 637         public function __sleep() {
 638                 throw new MWException( 'Database serialization may cause problems, since ' .
 639                         'the connection is not restored on wakeup.' );
 640         }
 641
 642         /**
 643          * Given a DB type, construct the name of the appropriate child class of
 644          * DatabaseBase. This is designed to replace all of the manual stuff like:
 645          *    $class = 'Database' . ucfirst( strtolower( $dbType ) );
 646          * as well as validate against the canonical list of DB types we have
 647          *
 648          * This factory function is mostly useful for when you need to connect to a
 649          * database other than the MediaWiki default (such as for external auth,
 650          * an extension, et cetera). Do not use this to connect to the MediaWiki
 651          * database. Example uses in core:
 652          * @see LoadBalancer::reallyOpenConnection()
 653          * @see ForeignDBRepo::getMasterDB()
 654          * @see WebInstallerDBConnect::execute()
 655          *
 656          * @since 1.18
 657          *
 658          * @param string $dbType A possible DB type
 659          * @param array $p An array of options to pass to the constructor.
 660          *    Valid options are: host, user, password, dbname, flags, tablePrefix, schema, driver
 661          * @throws MWException If the database driver or extension cannot be found
 662          * @return DatabaseBase|null DatabaseBase subclass or null
 663          */
 664         final public static function factory( $dbType, $p = [] ) {
 665                 global $wgCommandLineMode;
 666
 667                 $canonicalDBTypes = [
 668                         'mysql' => [ 'mysqli', 'mysql' ],
 669                         'postgres' => [],
 670                         'sqlite' => [],
 671                         'oracle' => [],
 672                         'mssql' => [],
 673                 ];
 674
 675                 $driver = false;
 676                 $dbType = strtolower( $dbType );
 677                 if ( isset( $canonicalDBTypes[$dbType] ) && $canonicalDBTypes[$dbType] ) {
 678                         $possibleDrivers = $canonicalDBTypes[$dbType];
 679                         if ( !empty( $p['driver'] ) ) {
 680                                 if ( in_array( $p['driver'], $possibleDrivers ) ) {
 681                                         $driver = $p['driver'];
 682                                 } else {
 683                                         throw new MWException( __METHOD__ .
 684                                                 " cannot construct Database with type '$dbType' and driver '{$p['driver']}'" );
 685                                 }
 686                         } else {
 687                                 foreach ( $possibleDrivers as $posDriver ) {
 688                                         if ( extension_loaded( $posDriver ) ) {
 689                                                 $driver = $posDriver;
 690                                                 break;
 691                                         }
 692                                 }
 693                         }
 694                 } else {
 695                         $driver = $dbType;
 696                 }
 697                 if ( $driver === false ) {
 698                         throw new MWException( __METHOD__ .
 699                                 " no viable database extension found for type '$dbType'" );
 700                 }
 701
 702                 // Determine schema defaults. Currently Microsoft SQL Server uses $wgDBmwschema,
 703                 // and everything else doesn't use a schema (e.g. null)
 704                 // Although postgres and oracle support schemas, we don't use them (yet)
 705                 // to maintain backwards compatibility
 706                 $defaultSchemas = [
 707                         'mssql' => 'get from global',
 708                 ];
 709
 710                 $class = 'Database' . ucfirst( $driver );
 711                 if ( class_exists( $class ) && is_subclass_of( $class, 'DatabaseBase' ) ) {
 712                         // Resolve some defaults for b/c
 713                         $p['host'] = isset( $p['host'] ) ? $p['host'] : false;
 714                         $p['user'] = isset( $p['user'] ) ? $p['user'] : false;
 715                         $p['password'] = isset( $p['password'] ) ? $p['password'] : false;
 716                         $p['dbname'] = isset( $p['dbname'] ) ? $p['dbname'] : false;
 717                         $p['flags'] = isset( $p['flags'] ) ? $p['flags'] : 0;
 718                         $p['variables'] = isset( $p['variables'] ) ? $p['variables'] : [];
 719                         $p['tablePrefix'] = isset( $p['tablePrefix'] ) ? $p['tablePrefix'] : 'get from global';
 720                         if ( !isset( $p['schema'] ) ) {
 721                                 $p['schema'] = isset( $defaultSchemas[$dbType] ) ? $defaultSchemas[$dbType] : null;
 722                         }
 723                         $p['foreign'] = isset( $p['foreign'] ) ? $p['foreign'] : false;
 724                         $p['cliMode'] = $wgCommandLineMode;
 725
 726                         return new $class( $p );
 727                 } else {
 728                         return null;
 729                 }
 730         }
 731
 732         protected function installErrorHandler() {
 733                 $this->mPHPError = false;
 734                 $this->htmlErrors = ini_set( 'html_errors', '0' );
 735                 set_error_handler( [ $this, 'connectionErrorHandler' ] );
 736         }
 737
 738         /**
 739          * @return bool|string
 740          */
 741         protected function restoreErrorHandler() {
 742                 restore_error_handler();
 743                 if ( $this->htmlErrors !== false ) {
 744                         ini_set( 'html_errors', $this->htmlErrors );
 745                 }
 746                 if ( $this->mPHPError ) {
 747                         $error = preg_replace( '!\[<a.*</a>\]!', '', $this->mPHPError );
 748                         $error = preg_replace( '!^.*?:\s?(.*)$!', '$1', $error );
 749
 750                         return $error;
 751                 } else {
 752                         return false;
 753                 }
 754         }
 755
 756         /**
 757          * @param int $errno
 758          * @param string $errstr
 759          */
 760         public function connectionErrorHandler( $errno, $errstr ) {
 761                 $this->mPHPError = $errstr;
 762         }
 763
 764         /**
 765          * Create a log context to pass to wfLogDBError or other logging functions.
 766          *
 767          * @param array $extras Additional data to add to context
 768          * @return array
 769          */
 770         protected function getLogContext( array $extras = [] ) {
 771                 return array_merge(
 772                         [
 773                                 'db_server' => $this->mServer,
 774                                 'db_name' => $this->mDBname,
 775                                 'db_user' => $this->mUser,
 776                         ],
 777                         $extras
 778                 );
 779         }
 780
 781         public function close() {
 782                 if ( $this->mConn ) {
 783                         if ( $this->trxLevel() ) {
 784                                 if ( !$this->mTrxAutomatic ) {
 785                                         wfWarn( "Transaction still in progress (from {$this->mTrxFname}), " .
 786                                                 " performing implicit commit before closing connection!" );
 787                                 }
 788
 789                                 $this->commit( __METHOD__, self::FLUSHING_INTERNAL );
 790                         }
 791
 792                         $closed = $this->closeConnection();
 793                         $this->mConn = false;
 794                 } elseif ( $this->mTrxIdleCallbacks || $this->mTrxEndCallbacks ) { // sanity
 795                         throw new MWException( "Transaction callbacks still pending." );
 796                 } else {
 797                         $closed = true;
 798                 }
 799                 $this->mOpened = false;
 800
 801                 return $closed;
 802         }
 803
 804         /**
 805          * Make sure isOpen() returns true as a sanity check
 806          *
 807          * @throws DBUnexpectedError
 808          */
 809         protected function assertOpen() {
 810                 if ( !$this->isOpen() ) {
 811                         throw new DBUnexpectedError( $this, "DB connection was already closed." );
 812                 }
 813         }
 814
 815         /**
 816          * Closes underlying database connection
 817          * @since 1.20
 818          * @return bool Whether connection was closed successfully
 819          */
 820         abstract protected function closeConnection();
 821
 822         function reportConnectionError( $error = 'Unknown error' ) {
 823                 $myError = $this->lastError();
 824                 if ( $myError ) {
 825                         $error = $myError;
 826                 }
 827
 828                 # New method
 829                 throw new DBConnectionError( $this, $error );
 830         }
 831
 832         /**
 833          * The DBMS-dependent part of query()
 834          *
 835          * @param string $sql SQL query.
 836          * @return ResultWrapper|bool Result object to feed to fetchObject,
 837          *   fetchRow, ...; or false on failure
 838          */
 839         abstract protected function doQuery( $sql );
 840
 841         /**
 842          * Determine whether a query writes to the DB.
 843          * Should return true if unsure.
 844          *
 845          * @param string $sql
 846          * @return bool
 847          */
 848         protected function isWriteQuery( $sql ) {
 849                 return !preg_match(
 850                         '/^(?:SELECT|BEGIN|ROLLBACK|COMMIT|SET|SHOW|EXPLAIN|\(SELECT)\b/i', $sql );
 851         }
 852
 853         /**
 854          * @param $sql
 855          * @return string|null
 856          */
 857         protected function getQueryVerb( $sql ) {
 858                 return preg_match( '/^\s*([a-z]+)/i', $sql, $m ) ? strtoupper( $m[1] ) : null;
 859         }
 860
 861         /**
 862          * Determine whether a SQL statement is sensitive to isolation level.
 863          * A SQL statement is considered transactable if its result could vary
 864          * depending on the transaction isolation level. Operational commands
 865          * such as 'SET' and 'SHOW' are not considered to be transactable.
 866          *
 867          * @param string $sql
 868          * @return bool
 869          */
 870         protected function isTransactableQuery( $sql ) {
 871                 $verb = $this->getQueryVerb( $sql );
 872                 return !in_array( $verb, [ 'BEGIN', 'COMMIT', 'ROLLBACK', 'SHOW', 'SET' ], true );
 873         }
 874
 875         public function query( $sql, $fname = __METHOD__, $tempIgnore = false ) {
 876                 global $wgUser;
 877
 878                 $priorWritesPending = $this->writesOrCallbacksPending();
 879                 $this->mLastQuery = $sql;
 880
 881                 $isWrite = $this->isWriteQuery( $sql );
 882                 if ( $isWrite ) {
 883                         $reason = $this->getReadOnlyReason();
 884                         if ( $reason !== false ) {
 885                                 throw new DBReadOnlyError( $this, "Database is read-only: $reason" );
 886                         }
 887                         # Set a flag indicating that writes have been done
 888                         $this->mDoneWrites = microtime( true );
 889                 }
 890
 891                 # Add a comment for easy SHOW PROCESSLIST interpretation
 892                 if ( is_object( $wgUser ) && $wgUser->isItemLoaded( 'name' ) ) {
 893                         $userName = $wgUser->getName();
 894                         if ( mb_strlen( $userName ) > 15 ) {
 895                                 $userName = mb_substr( $userName, 0, 15 ) . '...';
 896                         }
 897                         $userName = str_replace( '/', '', $userName );
 898                 } else {
 899                         $userName = '';
 900                 }
 901
 902                 // Add trace comment to the begin of the sql string, right after the operator.
 903                 // Or, for one-word queries (like "BEGIN" or COMMIT") add it to the end (bug 42598)
 904                 $commentedSql = preg_replace( '/\s|$/', " /* $fname $userName */ ", $sql, 1 );
 905
 906                 # Start implicit transactions that wrap the request if DBO_TRX is enabled
 907                 if ( !$this->mTrxLevel && $this->getFlag( DBO_TRX )
 908                         && $this->isTransactableQuery( $sql )
 909                 ) {
 910                         $this->begin( __METHOD__ . " ($fname)", self::TRANSACTION_INTERNAL );
 911                         $this->mTrxAutomatic = true;
 912                 }
 913
 914                 # Keep track of whether the transaction has write queries pending
 915                 if ( $this->mTrxLevel && !$this->mTrxDoneWrites && $isWrite ) {
 916                         $this->mTrxDoneWrites = true;
 917                         $this->getTransactionProfiler()->transactionWritingIn(
 918                                 $this->mServer, $this->mDBname, $this->mTrxShortId );
 919                 }
 920
 921                 if ( $this->debug() ) {
 922                         wfDebugLog( 'queries', sprintf( "%s: %s", $this->mDBname, $commentedSql ) );
 923                 }
 924
 925                 # Avoid fatals if close() was called
 926                 $this->assertOpen();
 927
 928                 # Send the query to the server
 929                 $ret = $this->doProfiledQuery( $sql, $commentedSql, $isWrite, $fname );
 930
 931                 # Try reconnecting if the connection was lost
 932                 if ( false === $ret && $this->wasErrorReissuable() ) {
 933                         $recoverable = $this->canRecoverFromDisconnect( $sql, $priorWritesPending );
 934                         # Stash the last error values before anything might clear them
 935                         $lastError = $this->lastError();
 936                         $lastErrno = $this->lastErrno();
 937                         # Update state tracking to reflect transaction loss due to disconnection
 938                         $this->handleTransactionLoss();
 939                         wfDebug( "Connection lost, reconnecting...\n" );
 940                         if ( $this->reconnect() ) {
 941                                 wfDebug( "Reconnected\n" );
 942                                 $msg = __METHOD__ . ": lost connection to {$this->getServer()}; reconnected";
 943                                 wfDebugLog( 'DBPerformance', "$msg:\n" . wfBacktrace( true ) );
 944
 945                                 if ( !$recoverable ) {
 946                                         # Callers may catch the exception and continue to use the DB
 947                                         $this->reportQueryError( $lastError, $lastErrno, $sql, $fname );
 948                                 } else {
 949                                         # Should be safe to silently retry the query
 950                                         $ret = $this->doProfiledQuery( $sql, $commentedSql, $isWrite, $fname );
 951                                 }
 952                         } else {
 953                                 wfDebug( "Failed\n" );
 954                         }
 955                 }
 956
 957                 if ( false === $ret ) {
 958                         # Deadlocks cause the entire transaction to abort, not just the statement.
 959                         # http://dev.mysql.com/doc/refman/5.7/en/innodb-error-handling.html
 960                         # https://www.postgresql.org/docs/9.1/static/explicit-locking.html
 961                         if ( $this->wasDeadlock() ) {
 962                                 if ( $this->explicitTrxActive() || $priorWritesPending ) {
 963                                         $tempIgnore = false; // not recoverable
 964                                 }
 965                                 # Update state tracking to reflect transaction loss
 966                                 $this->handleTransactionLoss();
 967                         }
 968
 969                         $this->reportQueryError(
 970                                 $this->lastError(), $this->lastErrno(), $sql, $fname, $tempIgnore );
 971                 }
 972
 973                 $res = $this->resultObject( $ret );
 974
 975                 return $res;
 976         }
 977
 978         private function doProfiledQuery( $sql, $commentedSql, $isWrite, $fname ) {
 979                 $isMaster = !is_null( $this->getLBInfo( 'master' ) );
 980                 # generalizeSQL() will probably cut down the query to reasonable
 981                 # logging size most of the time. The substr is really just a sanity check.
 982                 if ( $isMaster ) {
 983                         $queryProf = 'query-m: ' . substr( DatabaseBase::generalizeSQL( $sql ), 0, 255 );
 984                 } else {
 985                         $queryProf = 'query: ' . substr( DatabaseBase::generalizeSQL( $sql ), 0, 255 );
 986                 }
 987
 988                 # Include query transaction state
 989                 $queryProf .= $this->mTrxShortId ? " [TRX#{$this->mTrxShortId}]" : "";
 990
 991                 $startTime = microtime( true );
 992                 $this->profiler->profileIn( $queryProf );
 993                 $ret = $this->doQuery( $commentedSql );
 994                 $this->profiler->profileOut( $queryProf );
 995                 $queryRuntime = max( microtime( true ) - $startTime, 0.0 );
 996
 997                 unset( $queryProfSection ); // profile out (if set)
 998
 999                 if ( $ret !== false ) {
1000                         $this->lastPing = $startTime;
1001                         if ( $isWrite && $this->mTrxLevel ) {
1002                                 $this->updateTrxWriteQueryTime( $sql, $queryRuntime );
1003                                 $this->mTrxWriteCallers[] = $fname;
1004                         }
1005                 }
1006
1007                 if ( $sql === self::PING_QUERY ) {
1008                         $this->mRTTEstimate = $queryRuntime;
1009                 }
1010
1011                 $this->getTransactionProfiler()->recordQueryCompletion(
1012                         $queryProf, $startTime, $isWrite, $this->affectedRows()
1013                 );
1014                 MWDebug::query( $sql, $fname, $isMaster, $queryRuntime );
1015
1016                 return $ret;
1017         }
1018
1019         /**
1020          * Update the estimated run-time of a query, not counting large row lock times
1021          *
1022          * LoadBalancer can be set to rollback transactions that will create huge replication
1023          * lag. It bases this estimate off of pendingWriteQueryDuration(). Certain simple
1024          * queries, like inserting a row can take a long time due to row locking. This method
1025          * uses some simple heuristics to discount those cases.
1026          *
1027          * @param string $sql A SQL write query
1028          * @param float $runtime Total runtime, including RTT
1029          */
1030         private function updateTrxWriteQueryTime( $sql, $runtime ) {
1031                 $indicativeOfSlaveRuntime = true;
1032                 if ( $runtime > self::SLOW_WRITE_SEC ) {
1033                         $verb = $this->getQueryVerb( $sql );
1034                         // insert(), upsert(), replace() are fast unless bulky in size or blocked on locks
1035                         if ( $verb === 'INSERT' ) {
1036                                 $indicativeOfSlaveRuntime = $this->affectedRows() > self::SMALL_WRITE_ROWS;
1037                         } elseif ( $verb === 'REPLACE' ) {
1038                                 $indicativeOfSlaveRuntime = $this->affectedRows() > self::SMALL_WRITE_ROWS / 2;
1039                         }
1040                 }
1041
1042                 $this->mTrxWriteDuration += $runtime;
1043                 $this->mTrxWriteQueryCount += 1;
1044                 if ( $indicativeOfSlaveRuntime ) {
1045                         $this->mTrxWriteAdjDuration += $runtime;
1046                         $this->mTrxWriteAdjQueryCount += 1;
1047                 }
1048         }
1049
1050         private function canRecoverFromDisconnect( $sql, $priorWritesPending ) {
1051                 # Transaction dropped; this can mean lost writes, or REPEATABLE-READ snapshots.
1052                 # Dropped connections also mean that named locks are automatically released.
1053                 # Only allow error suppression in autocommit mode or when the lost transaction
1054                 # didn't matter anyway (aside from DBO_TRX snapshot loss).
1055                 if ( $this->mNamedLocksHeld ) {
1056                         return false; // possible critical section violation
1057                 } elseif ( $sql === 'COMMIT' ) {
1058                         return !$priorWritesPending; // nothing written anyway? (T127428)
1059                 } elseif ( $sql === 'ROLLBACK' ) {
1060                         return true; // transaction lost...which is also what was requested :)
1061                 } elseif ( $this->explicitTrxActive() ) {
1062                         return false; // don't drop atomocity
1063                 } elseif ( $priorWritesPending ) {
1064                         return false; // prior writes lost from implicit transaction
1065                 }
1066
1067                 return true;
1068         }
1069
1070         private function handleTransactionLoss() {
1071                 $this->mTrxLevel = 0;
1072                 $this->mTrxIdleCallbacks = []; // bug 65263
1073                 $this->mTrxPreCommitCallbacks = []; // bug 65263
1074                 try {
1075                         // Handle callbacks in mTrxEndCallbacks
1076                         $this->runOnTransactionIdleCallbacks( self::TRIGGER_ROLLBACK );
1077                         $this->runTransactionListenerCallbacks( self::TRIGGER_ROLLBACK );
1078                         return null;
1079                 } catch ( Exception $e ) {
1080                         // Already logged; move on...
1081                         return $e;
1082                 }
1083         }
1084
1085         public function reportQueryError( $error, $errno, $sql, $fname, $tempIgnore = false ) {
1086                 if ( $this->ignoreErrors() || $tempIgnore ) {
1087                         wfDebug( "SQL ERROR (ignored): $error\n" );
1088                 } else {
1089                         $sql1line = mb_substr( str_replace( "\n", "\\n", $sql ), 0, 5 * 1024 );
1090                         wfLogDBError(
1091                                 "{fname}\t{db_server}\t{errno}\t{error}\t{sql1line}",
1092                                 $this->getLogContext( [
1093                                         'method' => __METHOD__,
1094                                         'errno' => $errno,
1095                                         'error' => $error,
1096                                         'sql1line' => $sql1line,
1097                                         'fname' => $fname,
1098                                 ] )
1099                         );
1100                         wfDebug( "SQL ERROR: " . $error . "\n" );
1101                         throw new DBQueryError( $this, $error, $errno, $sql, $fname );
1102                 }
1103         }
1104
1105         /**
1106          * Intended to be compatible with the PEAR::DB wrapper functions.
1107          * http://pear.php.net/manual/en/package.database.db.intro-execute.php
1108          *
1109          * ? = scalar value, quoted as necessary
1110          * ! = raw SQL bit (a function for instance)
1111          * & = filename; reads the file and inserts as a blob
1112          *     (we don't use this though...)
1113          *
1114          * @param string $sql
1115          * @param string $func
1116          *
1117          * @return array
1118          */
1119         protected function prepare( $sql, $func = 'DatabaseBase::prepare' ) {
1120                 /* MySQL doesn't support prepared statements (yet), so just
1121                  * pack up the query for reference. We'll manually replace
1122                  * the bits later.
1123                  */
1124                 return [ 'query' => $sql, 'func' => $func ];
1125         }
1126
1127         /**
1128          * Free a prepared query, generated by prepare().
1129          * @param string $prepared
1130          */
1131         protected function freePrepared( $prepared ) {
1132                 /* No-op by default */
1133         }
1134
1135         /**
1136          * Execute a prepared query with the various arguments
1137          * @param string $prepared The prepared sql
1138          * @param mixed $args Either an array here, or put scalars as varargs
1139          *
1140          * @return ResultWrapper
1141          */
1142         public function execute( $prepared, $args = null ) {
1143                 if ( !is_array( $args ) ) {
1144                         # Pull the var args
1145                         $args = func_get_args();
1146                         array_shift( $args );
1147                 }
1148
1149                 $sql = $this->fillPrepared( $prepared['query'], $args );
1150
1151                 return $this->query( $sql, $prepared['func'] );
1152         }
1153
1154         /**
1155          * For faking prepared SQL statements on DBs that don't support it directly.
1156          *
1157          * @param string $preparedQuery A 'preparable' SQL statement
1158          * @param array $args Array of Arguments to fill it with
1159          * @return string Executable SQL
1160          */
1161         public function fillPrepared( $preparedQuery, $args ) {
1162                 reset( $args );
1163                 $this->preparedArgs =& $args;
1164
1165                 return preg_replace_callback( '/(\\\\[?!&]|[?!&])/',
1166                         [ &$this, 'fillPreparedArg' ], $preparedQuery );
1167         }
1168
1169         /**
1170          * preg_callback func for fillPrepared()
1171          * The arguments should be in $this->preparedArgs and must not be touched
1172          * while we're doing this.
1173          *
1174          * @param array $matches
1175          * @throws DBUnexpectedError
1176          * @return string
1177          */
1178         protected function fillPreparedArg( $matches ) {
1179                 switch ( $matches[1] ) {
1180                         case '\\?':
1181                                 return '?';
1182                         case '\\!':
1183                                 return '!';
1184                         case '\\&':
1185                                 return '&';
1186                 }
1187
1188                 list( /* $n */, $arg ) = each( $this->preparedArgs );
1189
1190                 switch ( $matches[1] ) {
1191                         case '?':
1192                                 return $this->addQuotes( $arg );
1193                         case '!':
1194                                 return $arg;
1195                         case '&':
1196                                 # return $this->addQuotes( file_get_contents( $arg ) );
1197                                 throw new DBUnexpectedError(
1198                                         $this,
1199                                         '& mode is not implemented. If it\'s really needed, uncomment the line above.'
1200                                 );
1201                         default:
1202                                 throw new DBUnexpectedError(
1203                                         $this,
1204                                         'Received invalid match. This should never happen!'
1205                                 );
1206                 }
1207         }
1208
1209         public function freeResult( $res ) {
1210         }
1211
1212         public function selectField(
1213                 $table, $var, $cond = '', $fname = __METHOD__, $options = []
1214         ) {
1215                 if ( $var === '*' ) { // sanity
1216                         throw new DBUnexpectedError( $this, "Cannot use a * field: got '$var'" );
1217                 }
1218
1219                 if ( !is_array( $options ) ) {
1220                         $options = [ $options ];
1221                 }
1222
1223                 $options['LIMIT'] = 1;
1224
1225                 $res = $this->select( $table, $var, $cond, $fname, $options );
1226                 if ( $res === false || !$this->numRows( $res ) ) {
1227                         return false;
1228                 }
1229
1230                 $row = $this->fetchRow( $res );
1231
1232                 if ( $row !== false ) {
1233                         return reset( $row );
1234                 } else {
1235                         return false;
1236                 }
1237         }
1238
1239         public function selectFieldValues(
1240                 $table, $var, $cond = '', $fname = __METHOD__, $options = [], $join_conds = []
1241         ) {
1242                 if ( $var === '*' ) { // sanity
1243                         throw new DBUnexpectedError( $this, "Cannot use a * field" );
1244                 } elseif ( !is_string( $var ) ) { // sanity
1245                         throw new DBUnexpectedError( $this, "Cannot use an array of fields" );
1246                 }
1247
1248                 if ( !is_array( $options ) ) {
1249                         $options = [ $options ];
1250                 }
1251
1252                 $res = $this->select( $table, $var, $cond, $fname, $options, $join_conds );
1253                 if ( $res === false ) {
1254                         return false;
1255                 }
1256
1257                 $values = [];
1258                 foreach ( $res as $row ) {
1259                         $values[] = $row->$var;
1260                 }
1261
1262                 return $values;
1263         }
1264
1265         /**
1266          * Returns an optional USE INDEX clause to go after the table, and a
1267          * string to go at the end of the query.
1268          *
1269          * @param array $options Associative array of options to be turned into
1270          *   an SQL query, valid keys are listed in the function.
1271          * @return array
1272          * @see DatabaseBase::select()
1273          */
1274         public function makeSelectOptions( $options ) {
1275                 $preLimitTail = $postLimitTail = '';
1276                 $startOpts = '';
1277
1278                 $noKeyOptions = [];
1279
1280                 foreach ( $options as $key => $option ) {
1281                         if ( is_numeric( $key ) ) {
1282                                 $noKeyOptions[$option] = true;
1283                         }
1284                 }
1285
1286                 $preLimitTail .= $this->makeGroupByWithHaving( $options );
1287
1288                 $preLimitTail .= $this->makeOrderBy( $options );
1289
1290                 // if (isset($options['LIMIT'])) {
1291                 //      $tailOpts .= $this->limitResult('', $options['LIMIT'],
1292                 //              isset($options['OFFSET']) ? $options['OFFSET']
1293                 //              : false);
1294                 // }
1295
1296                 if ( isset( $noKeyOptions['FOR UPDATE'] ) ) {
1297                         $postLimitTail .= ' FOR UPDATE';
1298                 }
1299
1300                 if ( isset( $noKeyOptions['LOCK IN SHARE MODE'] ) ) {
1301                         $postLimitTail .= ' LOCK IN SHARE MODE';
1302                 }
1303
1304                 if ( isset( $noKeyOptions['DISTINCT'] ) || isset( $noKeyOptions['DISTINCTROW'] ) ) {
1305                         $startOpts .= 'DISTINCT';
1306                 }
1307
1308                 # Various MySQL extensions
1309                 if ( isset( $noKeyOptions['STRAIGHT_JOIN'] ) ) {
1310                         $startOpts .= ' /*! STRAIGHT_JOIN */';
1311                 }
1312
1313                 if ( isset( $noKeyOptions['HIGH_PRIORITY'] ) ) {
1314                         $startOpts .= ' HIGH_PRIORITY';
1315                 }
1316
1317                 if ( isset( $noKeyOptions['SQL_BIG_RESULT'] ) ) {
1318                         $startOpts .= ' SQL_BIG_RESULT';
1319                 }
1320
1321                 if ( isset( $noKeyOptions['SQL_BUFFER_RESULT'] ) ) {
1322                         $startOpts .= ' SQL_BUFFER_RESULT';
1323                 }
1324
1325                 if ( isset( $noKeyOptions['SQL_SMALL_RESULT'] ) ) {
1326                         $startOpts .= ' SQL_SMALL_RESULT';
1327                 }
1328
1329                 if ( isset( $noKeyOptions['SQL_CALC_FOUND_ROWS'] ) ) {
1330                         $startOpts .= ' SQL_CALC_FOUND_ROWS';
1331                 }
1332
1333                 if ( isset( $noKeyOptions['SQL_CACHE'] ) ) {
1334                         $startOpts .= ' SQL_CACHE';
1335                 }
1336
1337                 if ( isset( $noKeyOptions['SQL_NO_CACHE'] ) ) {
1338                         $startOpts .= ' SQL_NO_CACHE';
1339                 }
1340
1341                 if ( isset( $options['USE INDEX'] ) && is_string( $options['USE INDEX'] ) ) {
1342                         $useIndex = $this->useIndexClause( $options['USE INDEX'] );
1343                 } else {
1344                         $useIndex = '';
1345                 }
1346
1347                 return [ $startOpts, $useIndex, $preLimitTail, $postLimitTail ];
1348         }
1349
1350         /**
1351          * Returns an optional GROUP BY with an optional HAVING
1352          *
1353          * @param array $options Associative array of options
1354          * @return string
1355          * @see DatabaseBase::select()
1356          * @since 1.21
1357          */
1358         public function makeGroupByWithHaving( $options ) {
1359                 $sql = '';
1360                 if ( isset( $options['GROUP BY'] ) ) {
1361                         $gb = is_array( $options['GROUP BY'] )
1362                                 ? implode( ',', $options['GROUP BY'] )
1363                                 : $options['GROUP BY'];
1364                         $sql .= ' GROUP BY ' . $gb;
1365                 }
1366                 if ( isset( $options['HAVING'] ) ) {
1367                         $having = is_array( $options['HAVING'] )
1368                                 ? $this->makeList( $options['HAVING'], LIST_AND )
1369                                 : $options['HAVING'];
1370                         $sql .= ' HAVING ' . $having;
1371                 }
1372
1373                 return $sql;
1374         }
1375
1376         /**
1377          * Returns an optional ORDER BY
1378          *
1379          * @param array $options Associative array of options
1380          * @return string
1381          * @see DatabaseBase::select()
1382          * @since 1.21
1383          */
1384         public function makeOrderBy( $options ) {
1385                 if ( isset( $options['ORDER BY'] ) ) {
1386                         $ob = is_array( $options['ORDER BY'] )
1387                                 ? implode( ',', $options['ORDER BY'] )
1388                                 : $options['ORDER BY'];
1389
1390                         return ' ORDER BY ' . $ob;
1391                 }
1392
1393                 return '';
1394         }
1395
1396         // See IDatabase::select for the docs for this function
1397         public function select( $table, $vars, $conds = '', $fname = __METHOD__,
1398                 $options = [], $join_conds = [] ) {
1399                 $sql = $this->selectSQLText( $table, $vars, $conds, $fname, $options, $join_conds );
1400
1401                 return $this->query( $sql, $fname );
1402         }
1403
1404         public function selectSQLText( $table, $vars, $conds = '', $fname = __METHOD__,
1405                 $options = [], $join_conds = []
1406         ) {
1407                 if ( is_array( $vars ) ) {
1408                         $vars = implode( ',', $this->fieldNamesWithAlias( $vars ) );
1409                 }
1410
1411                 $options = (array)$options;
1412                 $useIndexes = ( isset( $options['USE INDEX'] ) && is_array( $options['USE INDEX'] ) )
1413                         ? $options['USE INDEX']
1414                         : [];
1415
1416                 if ( is_array( $table ) ) {
1417                         $from = ' FROM ' .
1418                                 $this->tableNamesWithUseIndexOrJOIN( $table, $useIndexes, $join_conds );
1419                 } elseif ( $table != '' ) {
1420                         if ( $table[0] == ' ' ) {
1421                                 $from = ' FROM ' . $table;
1422                         } else {
1423                                 $from = ' FROM ' .
1424                                         $this->tableNamesWithUseIndexOrJOIN( [ $table ], $useIndexes, [] );
1425                         }
1426                 } else {
1427                         $from = '';
1428                 }
1429
1430                 list( $startOpts, $useIndex, $preLimitTail, $postLimitTail ) =
1431                         $this->makeSelectOptions( $options );
1432
1433                 if ( !empty( $conds ) ) {
1434                         if ( is_array( $conds ) ) {
1435                                 $conds = $this->makeList( $conds, LIST_AND );
1436                         }
1437                         $sql = "SELECT $startOpts $vars $from $useIndex WHERE $conds $preLimitTail";
1438                 } else {
1439                         $sql = "SELECT $startOpts $vars $from $useIndex $preLimitTail";
1440                 }
1441
1442                 if ( isset( $options['LIMIT'] ) ) {
1443                         $sql = $this->limitResult( $sql, $options['LIMIT'],
1444                                 isset( $options['OFFSET'] ) ? $options['OFFSET'] : false );
1445                 }
1446                 $sql = "$sql $postLimitTail";
1447
1448                 if ( isset( $options['EXPLAIN'] ) ) {
1449                         $sql = 'EXPLAIN ' . $sql;
1450                 }
1451
1452                 return $sql;
1453         }
1454
1455         public function selectRow( $table, $vars, $conds, $fname = __METHOD__,
1456                 $options = [], $join_conds = []
1457         ) {
1458                 $options = (array)$options;
1459                 $options['LIMIT'] = 1;
1460                 $res = $this->select( $table, $vars, $conds, $fname, $options, $join_conds );
1461
1462                 if ( $res === false ) {
1463                         return false;
1464                 }
1465
1466                 if ( !$this->numRows( $res ) ) {
1467                         return false;
1468                 }
1469
1470                 $obj = $this->fetchObject( $res );
1471
1472                 return $obj;
1473         }
1474
1475         public function estimateRowCount(
1476                 $table, $vars = '*', $conds = '', $fname = __METHOD__, $options = []
1477         ) {
1478                 $rows = 0;
1479                 $res = $this->select( $table, [ 'rowcount' => 'COUNT(*)' ], $conds, $fname, $options );
1480
1481                 if ( $res ) {
1482                         $row = $this->fetchRow( $res );
1483                         $rows = ( isset( $row['rowcount'] ) ) ? (int)$row['rowcount'] : 0;
1484                 }
1485
1486                 return $rows;
1487         }
1488
1489         public function selectRowCount(
1490                 $tables, $vars = '*', $conds = '', $fname = __METHOD__, $options = [], $join_conds = []
1491         ) {
1492                 $rows = 0;
1493                 $sql = $this->selectSQLText( $tables, '1', $conds, $fname, $options, $join_conds );
1494                 $res = $this->query( "SELECT COUNT(*) AS rowcount FROM ($sql) tmp_count", $fname );
1495
1496                 if ( $res ) {
1497                         $row = $this->fetchRow( $res );
1498                         $rows = ( isset( $row['rowcount'] ) ) ? (int)$row['rowcount'] : 0;
1499                 }
1500
1501                 return $rows;
1502         }
1503
1504         /**
1505          * Removes most variables from an SQL query and replaces them with X or N for numbers.
1506          * It's only slightly flawed. Don't use for anything important.
1507          *
1508          * @param string $sql A SQL Query
1509          *
1510          * @return string
1511          */
1512         protected static function generalizeSQL( $sql ) {
1513                 # This does the same as the regexp below would do, but in such a way
1514                 # as to avoid crashing php on some large strings.
1515                 # $sql = preg_replace( "/'([^\\\\']|\\\\.)*'|\"([^\\\\\"]|\\\\.)*\"/", "'X'", $sql );
1516
1517                 $sql = str_replace( "\\\\", '', $sql );
1518                 $sql = str_replace( "\\'", '', $sql );
1519                 $sql = str_replace( "\\\"", '', $sql );
1520                 $sql = preg_replace( "/'.*'/s", "'X'", $sql );
1521                 $sql = preg_replace( '/".*"/s', "'X'", $sql );
1522
1523                 # All newlines, tabs, etc replaced by single space
1524                 $sql = preg_replace( '/\s+/', ' ', $sql );
1525
1526                 # All numbers => N,
1527                 # except the ones surrounded by characters, e.g. l10n
1528                 $sql = preg_replace( '/-?\d+(,-?\d+)+/s', 'N,...,N', $sql );
1529                 $sql = preg_replace( '/(?<![a-zA-Z])-?\d+(?![a-zA-Z])/s', 'N', $sql );
1530
1531                 return $sql;
1532         }
1533
1534         public function fieldExists( $table, $field, $fname = __METHOD__ ) {
1535                 $info = $this->fieldInfo( $table, $field );
1536
1537                 return (bool)$info;
1538         }
1539
1540         public function indexExists( $table, $index, $fname = __METHOD__ ) {
1541                 if ( !$this->tableExists( $table ) ) {
1542                         return null;
1543                 }
1544
1545                 $info = $this->indexInfo( $table, $index, $fname );
1546                 if ( is_null( $info ) ) {
1547                         return null;
1548                 } else {
1549                         return $info !== false;
1550                 }
1551         }
1552
1553         public function tableExists( $table, $fname = __METHOD__ ) {
1554                 $table = $this->tableName( $table );
1555                 $old = $this->ignoreErrors( true );
1556                 $res = $this->query( "SELECT 1 FROM $table LIMIT 1", $fname );
1557                 $this->ignoreErrors( $old );
1558
1559                 return (bool)$res;
1560         }
1561
1562         public function indexUnique( $table, $index ) {
1563                 $indexInfo = $this->indexInfo( $table, $index );
1564
1565                 if ( !$indexInfo ) {
1566                         return null;
1567                 }
1568
1569                 return !$indexInfo[0]->Non_unique;
1570         }
1571
1572         /**
1573          * Helper for DatabaseBase::insert().
1574          *
1575          * @param array $options
1576          * @return string
1577          */
1578         protected function makeInsertOptions( $options ) {
1579                 return implode( ' ', $options );
1580         }
1581
1582         public function insert( $table, $a, $fname = __METHOD__, $options = [] ) {
1583                 # No rows to insert, easy just return now
1584                 if ( !count( $a ) ) {
1585                         return true;
1586                 }
1587
1588                 $table = $this->tableName( $table );
1589
1590                 if ( !is_array( $options ) ) {
1591                         $options = [ $options ];
1592                 }
1593
1594                 $fh = null;
1595                 if ( isset( $options['fileHandle'] ) ) {
1596                         $fh = $options['fileHandle'];
1597                 }
1598                 $options = $this->makeInsertOptions( $options );
1599
1600                 if ( isset( $a[0] ) && is_array( $a[0] ) ) {
1601                         $multi = true;
1602                         $keys = array_keys( $a[0] );
1603                 } else {
1604                         $multi = false;
1605                         $keys = array_keys( $a );
1606                 }
1607
1608                 $sql = 'INSERT ' . $options .
1609                         " INTO $table (" . implode( ',', $keys ) . ') VALUES ';
1610
1611                 if ( $multi ) {
1612                         $first = true;
1613                         foreach ( $a as $row ) {
1614                                 if ( $first ) {
1615                                         $first = false;
1616                                 } else {
1617                                         $sql .= ',';
1618                                 }
1619                                 $sql .= '(' . $this->makeList( $row ) . ')';
1620                         }
1621                 } else {
1622                         $sql .= '(' . $this->makeList( $a ) . ')';
1623                 }
1624
1625                 if ( $fh !== null && false === fwrite( $fh, $sql ) ) {
1626                         return false;
1627                 } elseif ( $fh !== null ) {
1628                         return true;
1629                 }
1630
1631                 return (bool)$this->query( $sql, $fname );
1632         }
1633
1634         /**
1635          * Make UPDATE options array for DatabaseBase::makeUpdateOptions
1636          *
1637          * @param array $options
1638          * @return array
1639          */
1640         protected function makeUpdateOptionsArray( $options ) {
1641                 if ( !is_array( $options ) ) {
1642                         $options = [ $options ];
1643                 }
1644
1645                 $opts = [];
1646
1647                 if ( in_array( 'LOW_PRIORITY', $options ) ) {
1648                         $opts[] = $this->lowPriorityOption();
1649                 }
1650
1651                 if ( in_array( 'IGNORE', $options ) ) {
1652                         $opts[] = 'IGNORE';
1653                 }
1654
1655                 return $opts;
1656         }
1657
1658         /**
1659          * Make UPDATE options for the DatabaseBase::update function
1660          *
1661          * @param array $options The options passed to DatabaseBase::update
1662          * @return string
1663          */
1664         protected function makeUpdateOptions( $options ) {
1665                 $opts = $this->makeUpdateOptionsArray( $options );
1666
1667                 return implode( ' ', $opts );
1668         }
1669
1670         function update( $table, $values, $conds, $fname = __METHOD__, $options = [] ) {
1671                 $table = $this->tableName( $table );
1672                 $opts = $this->makeUpdateOptions( $options );
1673                 $sql = "UPDATE $opts $table SET " . $this->makeList( $values, LIST_SET );
1674
1675                 if ( $conds !== [] && $conds !== '*' ) {
1676                         $sql .= " WHERE " . $this->makeList( $conds, LIST_AND );
1677                 }
1678
1679                 return $this->query( $sql, $fname );
1680         }
1681
1682         public function makeList( $a, $mode = LIST_COMMA ) {
1683                 if ( !is_array( $a ) ) {
1684                         throw new DBUnexpectedError( $this, 'DatabaseBase::makeList called with incorrect parameters' );
1685                 }
1686
1687                 $first = true;
1688                 $list = '';
1689
1690                 foreach ( $a as $field => $value ) {
1691                         if ( !$first ) {
1692                                 if ( $mode == LIST_AND ) {
1693                                         $list .= ' AND ';
1694                                 } elseif ( $mode == LIST_OR ) {
1695                                         $list .= ' OR ';
1696                                 } else {
1697                                         $list .= ',';
1698                                 }
1699                         } else {
1700                                 $first = false;
1701                         }
1702
1703                         if ( ( $mode == LIST_AND || $mode == LIST_OR ) && is_numeric( $field ) ) {
1704                                 $list .= "($value)";
1705                         } elseif ( ( $mode == LIST_SET ) && is_numeric( $field ) ) {
1706                                 $list .= "$value";
1707                         } elseif ( ( $mode == LIST_AND || $mode == LIST_OR ) && is_array( $value ) ) {
1708                                 // Remove null from array to be handled separately if found
1709                                 $includeNull = false;
1710                                 foreach ( array_keys( $value, null, true ) as $nullKey ) {
1711                                         $includeNull = true;
1712                                         unset( $value[$nullKey] );
1713                                 }
1714                                 if ( count( $value ) == 0 && !$includeNull ) {
1715                                         throw new MWException( __METHOD__ . ": empty input for field $field" );
1716                                 } elseif ( count( $value ) == 0 ) {
1717                                         // only check if $field is null
1718                                         $list .= "$field IS NULL";
1719                                 } else {
1720                                         // IN clause contains at least one valid element
1721                                         if ( $includeNull ) {
1722                                                 // Group subconditions to ensure correct precedence
1723                                                 $list .= '(';
1724                                         }
1725                                         if ( count( $value ) == 1 ) {
1726                                                 // Special-case single values, as IN isn't terribly efficient
1727                                                 // Don't necessarily assume the single key is 0; we don't
1728                                                 // enforce linear numeric ordering on other arrays here.
1729                                                 $value = array_values( $value )[0];
1730                                                 $list .= $field . " = " . $this->addQuotes( $value );
1731                                         } else {
1732                                                 $list .= $field . " IN (" . $this->makeList( $value ) . ") ";
1733                                         }
1734                                         // if null present in array, append IS NULL
1735                                         if ( $includeNull ) {
1736                                                 $list .= " OR $field IS NULL)";
1737                                         }
1738                                 }
1739                         } elseif ( $value === null ) {
1740                                 if ( $mode == LIST_AND || $mode == LIST_OR ) {
1741                                         $list .= "$field IS ";
1742                                 } elseif ( $mode == LIST_SET ) {
1743                                         $list .= "$field = ";
1744                                 }
1745                                 $list .= 'NULL';
1746                         } else {
1747                                 if ( $mode == LIST_AND || $mode == LIST_OR || $mode == LIST_SET ) {
1748                                         $list .= "$field = ";
1749                                 }
1750                                 $list .= $mode == LIST_NAMES ? $value : $this->addQuotes( $value );
1751                         }
1752                 }
1753
1754                 return $list;
1755         }
1756
1757         public function makeWhereFrom2d( $data, $baseKey, $subKey ) {
1758                 $conds = [];
1759
1760                 foreach ( $data as $base => $sub ) {
1761                         if ( count( $sub ) ) {
1762                                 $conds[] = $this->makeList(
1763                                         [ $baseKey => $base, $subKey => array_keys( $sub ) ],
1764                                         LIST_AND );
1765                         }
1766                 }
1767
1768                 if ( $conds ) {
1769                         return $this->makeList( $conds, LIST_OR );
1770                 } else {
1771                         // Nothing to search for...
1772                         return false;
1773                 }
1774         }
1775
1776         /**
1777          * Return aggregated value alias
1778          *
1779          * @param array $valuedata
1780          * @param string $valuename
1781          *
1782          * @return string
1783          */
1784         public function aggregateValue( $valuedata, $valuename = 'value' ) {
1785                 return $valuename;
1786         }
1787
1788         public function bitNot( $field ) {
1789                 return "(~$field)";
1790         }
1791
1792         public function bitAnd( $fieldLeft, $fieldRight ) {
1793                 return "($fieldLeft & $fieldRight)";
1794         }
1795
1796         public function bitOr( $fieldLeft, $fieldRight ) {
1797                 return "($fieldLeft | $fieldRight)";
1798         }
1799
1800         public function buildConcat( $stringList ) {
1801                 return 'CONCAT(' . implode( ',', $stringList ) . ')';
1802         }
1803
1804         public function buildGroupConcatField(
1805                 $delim, $table, $field, $conds = '', $join_conds = []
1806         ) {
1807                 $fld = "GROUP_CONCAT($field SEPARATOR " . $this->addQuotes( $delim ) . ')';
1808
1809                 return '(' . $this->selectSQLText( $table, $fld, $conds, null, [], $join_conds ) . ')';
1810         }
1811
1812         /**
1813          * @param string $field Field or column to cast
1814          * @return string
1815          * @since 1.28
1816          */
1817         public function buildStringCast( $field ) {
1818                 return $field;
1819         }
1820
1821         public function selectDB( $db ) {
1822                 # Stub. Shouldn't cause serious problems if it's not overridden, but
1823                 # if your database engine supports a concept similar to MySQL's
1824                 # databases you may as well.
1825                 $this->mDBname = $db;
1826
1827                 return true;
1828         }
1829
1830         public function getDBname() {
1831                 return $this->mDBname;
1832         }
1833
1834         public function getServer() {
1835                 return $this->mServer;
1836         }
1837
1838         /**
1839          * Format a table name ready for use in constructing an SQL query
1840          *
1841          * This does two important things: it quotes the table names to clean them up,
1842          * and it adds a table prefix if only given a table name with no quotes.
1843          *
1844          * All functions of this object which require a table name call this function
1845          * themselves. Pass the canonical name to such functions. This is only needed
1846          * when calling query() directly.
1847          *
1848          * @note This function does not sanitize user input. It is not safe to use
1849          *   this function to escape user input.
1850          * @param string $name Database table name
1851          * @param string $format One of:
1852          *   quoted - Automatically pass the table name through addIdentifierQuotes()
1853          *            so that it can be used in a query.
1854          *   raw - Do not add identifier quotes to the table name
1855          * @return string Full database name
1856          */
1857         public function tableName( $name, $format = 'quoted' ) {
1858                 global $wgSharedDB, $wgSharedPrefix, $wgSharedTables, $wgSharedSchema;
1859                 # Skip the entire process when we have a string quoted on both ends.
1860                 # Note that we check the end so that we will still quote any use of
1861                 # use of `database`.table. But won't break things if someone wants
1862                 # to query a database table with a dot in the name.
1863                 if ( $this->isQuotedIdentifier( $name ) ) {
1864                         return $name;
1865                 }
1866
1867                 # Lets test for any bits of text that should never show up in a table
1868                 # name. Basically anything like JOIN or ON which are actually part of
1869                 # SQL queries, but may end up inside of the table value to combine
1870                 # sql. Such as how the API is doing.
1871                 # Note that we use a whitespace test rather than a \b test to avoid
1872                 # any remote case where a word like on may be inside of a table name
1873                 # surrounded by symbols which may be considered word breaks.
1874                 if ( preg_match( '/(^|\s)(DISTINCT|JOIN|ON|AS)(\s|$)/i', $name ) !== 0 ) {
1875                         return $name;
1876                 }
1877
1878                 # Split database and table into proper variables.
1879                 # We reverse the explode so that database.table and table both output
1880                 # the correct table.
1881                 $dbDetails = explode( '.', $name, 3 );
1882                 if ( count( $dbDetails ) == 3 ) {
1883                         list( $database, $schema, $table ) = $dbDetails;
1884                         # We don't want any prefix added in this case
1885                         $prefix = '';
1886                 } elseif ( count( $dbDetails ) == 2 ) {
1887                         list( $database, $table ) = $dbDetails;
1888                         # We don't want any prefix added in this case
1889                         # In dbs that support it, $database may actually be the schema
1890                         # but that doesn't affect any of the functionality here
1891                         $prefix = '';
1892                         $schema = null;
1893                 } else {
1894                         list( $table ) = $dbDetails;
1895                         if ( $wgSharedDB !== null # We have a shared database
1896                                 && $this->mForeign == false # We're not working on a foreign database
1897                                 && !$this->isQuotedIdentifier( $table ) # Prevent shared tables listing '`table`'
1898                                 && in_array( $table, $wgSharedTables ) # A shared table is selected
1899                         ) {
1900                                 $database = $wgSharedDB;
1901                                 $schema = $wgSharedSchema === null ? $this->mSchema : $wgSharedSchema;
1902                                 $prefix = $wgSharedPrefix === null ? $this->mTablePrefix : $wgSharedPrefix;
1903                         } else {
1904                                 $database = null;
1905                                 $schema = $this->mSchema; # Default schema
1906                                 $prefix = $this->mTablePrefix; # Default prefix
1907                         }
1908                 }
1909
1910                 # Quote $table and apply the prefix if not quoted.
1911                 # $tableName might be empty if this is called from Database::replaceVars()
1912                 $tableName = "{$prefix}{$table}";
1913                 if ( $format == 'quoted' && !$this->isQuotedIdentifier( $tableName ) && $tableName !== '' ) {
1914                         $tableName = $this->addIdentifierQuotes( $tableName );
1915                 }
1916
1917                 # Quote $schema and merge it with the table name if needed
1918                 if ( strlen( $schema ) ) {
1919                         if ( $format == 'quoted' && !$this->isQuotedIdentifier( $schema ) ) {
1920                                 $schema = $this->addIdentifierQuotes( $schema );
1921                         }
1922                         $tableName = $schema . '.' . $tableName;
1923                 }
1924
1925                 # Quote $database and merge it with the table name if needed
1926                 if ( $database !== null ) {
1927                         if ( $format == 'quoted' && !$this->isQuotedIdentifier( $database ) ) {
1928                                 $database = $this->addIdentifierQuotes( $database );
1929                         }
1930                         $tableName = $database . '.' . $tableName;
1931                 }
1932
1933                 return $tableName;
1934         }
1935
1936         /**
1937          * Fetch a number of table names into an array
1938          * This is handy when you need to construct SQL for joins
1939          *
1940          * Example:
1941          * extract( $dbr->tableNames( 'user', 'watchlist' ) );
1942          * $sql = "SELECT wl_namespace,wl_title FROM $watchlist,$user
1943          *         WHERE wl_user=user_id AND wl_user=$nameWithQuotes";
1944          *
1945          * @return array
1946          */
1947         public function tableNames() {
1948                 $inArray = func_get_args();
1949                 $retVal = [];
1950
1951                 foreach ( $inArray as $name ) {
1952                         $retVal[$name] = $this->tableName( $name );
1953                 }
1954
1955                 return $retVal;
1956         }
1957
1958         /**
1959          * Fetch a number of table names into an zero-indexed numerical array
1960          * This is handy when you need to construct SQL for joins
1961          *
1962          * Example:
1963          * list( $user, $watchlist ) = $dbr->tableNamesN( 'user', 'watchlist' );
1964          * $sql = "SELECT wl_namespace,wl_title FROM $watchlist,$user
1965          *         WHERE wl_user=user_id AND wl_user=$nameWithQuotes";
1966          *
1967          * @return array
1968          */
1969         public function tableNamesN() {
1970                 $inArray = func_get_args();
1971                 $retVal = [];
1972
1973                 foreach ( $inArray as $name ) {
1974                         $retVal[] = $this->tableName( $name );
1975                 }
1976
1977                 return $retVal;
1978         }
1979
1980         /**
1981          * Get an aliased table name
1982          * e.g. tableName AS newTableName
1983          *
1984          * @param string $name Table name, see tableName()
1985          * @param string|bool $alias Alias (optional)
1986          * @return string SQL name for aliased table. Will not alias a table to its own name
1987          */
1988         public function tableNameWithAlias( $name, $alias = false ) {
1989                 if ( !$alias || $alias == $name ) {
1990                         return $this->tableName( $name );
1991                 } else {
1992                         return $this->tableName( $name ) . ' ' . $this->addIdentifierQuotes( $alias );
1993                 }
1994         }
1995
1996         /**
1997          * Gets an array of aliased table names
1998          *
1999          * @param array $tables [ [alias] => table ]
2000          * @return string[] See tableNameWithAlias()
2001          */
2002         public function tableNamesWithAlias( $tables ) {
2003                 $retval = [];
2004                 foreach ( $tables as $alias => $table ) {
2005                         if ( is_numeric( $alias ) ) {
2006                                 $alias = $table;
2007                         }
2008                         $retval[] = $this->tableNameWithAlias( $table, $alias );
2009                 }
2010
2011                 return $retval;
2012         }
2013
2014         /**
2015          * Get an aliased field name
2016          * e.g. fieldName AS newFieldName
2017          *
2018          * @param string $name Field name
2019          * @param string|bool $alias Alias (optional)
2020          * @return string SQL name for aliased field. Will not alias a field to its own name
2021          */
2022         public function fieldNameWithAlias( $name, $alias = false ) {
2023                 if ( !$alias || (string)$alias === (string)$name ) {
2024                         return $name;
2025                 } else {
2026                         return $name . ' AS ' . $this->addIdentifierQuotes( $alias ); // PostgreSQL needs AS
2027                 }
2028         }
2029
2030         /**
2031          * Gets an array of aliased field names
2032          *
2033          * @param array $fields [ [alias] => field ]
2034          * @return string[] See fieldNameWithAlias()
2035          */
2036         public function fieldNamesWithAlias( $fields ) {
2037                 $retval = [];
2038                 foreach ( $fields as $alias => $field ) {
2039                         if ( is_numeric( $alias ) ) {
2040                                 $alias = $field;
2041                         }
2042                         $retval[] = $this->fieldNameWithAlias( $field, $alias );
2043                 }
2044
2045                 return $retval;
2046         }
2047
2048         /**
2049          * Get the aliased table name clause for a FROM clause
2050          * which might have a JOIN and/or USE INDEX clause
2051          *
2052          * @param array $tables ( [alias] => table )
2053          * @param array $use_index Same as for select()
2054          * @param array $join_conds Same as for select()
2055          * @return string
2056          */
2057         protected function tableNamesWithUseIndexOrJOIN(
2058                 $tables, $use_index = [], $join_conds = []
2059         ) {
2060                 $ret = [];
2061                 $retJOIN = [];
2062                 $use_index = (array)$use_index;
2063                 $join_conds = (array)$join_conds;
2064
2065                 foreach ( $tables as $alias => $table ) {
2066                         if ( !is_string( $alias ) ) {
2067                                 // No alias? Set it equal to the table name
2068                                 $alias = $table;
2069                         }
2070                         // Is there a JOIN clause for this table?
2071                         if ( isset( $join_conds[$alias] ) ) {
2072                                 list( $joinType, $conds ) = $join_conds[$alias];
2073                                 $tableClause = $joinType;
2074                                 $tableClause .= ' ' . $this->tableNameWithAlias( $table, $alias );
2075                                 if ( isset( $use_index[$alias] ) ) { // has USE INDEX?
2076                                         $use = $this->useIndexClause( implode( ',', (array)$use_index[$alias] ) );
2077                                         if ( $use != '' ) {
2078                                                 $tableClause .= ' ' . $use;
2079                                         }
2080                                 }
2081                                 $on = $this->makeList( (array)$conds, LIST_AND );
2082                                 if ( $on != '' ) {
2083                                         $tableClause .= ' ON (' . $on . ')';
2084                                 }
2085
2086                                 $retJOIN[] = $tableClause;
2087                         } elseif ( isset( $use_index[$alias] ) ) {
2088                                 // Is there an INDEX clause for this table?
2089                                 $tableClause = $this->tableNameWithAlias( $table, $alias );
2090                                 $tableClause .= ' ' . $this->useIndexClause(
2091                                         implode( ',', (array)$use_index[$alias] )
2092                                 );
2093
2094                                 $ret[] = $tableClause;
2095                         } else {
2096                                 $tableClause = $this->tableNameWithAlias( $table, $alias );
2097
2098                                 $ret[] = $tableClause;
2099                         }
2100                 }
2101
2102                 // We can't separate explicit JOIN clauses with ',', use ' ' for those
2103                 $implicitJoins = !empty( $ret ) ? implode( ',', $ret ) : "";
2104                 $explicitJoins = !empty( $retJOIN ) ? implode( ' ', $retJOIN ) : "";
2105
2106                 // Compile our final table clause
2107                 return implode( ' ', [ $implicitJoins, $explicitJoins ] );
2108         }
2109
2110         /**
2111          * Get the name of an index in a given table.
2112          *
2113          * @param string $index
2114          * @return string
2115          */
2116         protected function indexName( $index ) {
2117                 // Backwards-compatibility hack
2118                 $renamed = [
2119                         'ar_usertext_timestamp' => 'usertext_timestamp',
2120                         'un_user_id' => 'user_id',
2121                         'un_user_ip' => 'user_ip',
2122                 ];
2123
2124                 if ( isset( $renamed[$index] ) ) {
2125                         return $renamed[$index];
2126                 } else {
2127                         return $index;
2128                 }
2129         }
2130
2131         public function addQuotes( $s ) {
2132                 if ( $s instanceof Blob ) {
2133                         $s = $s->fetch();
2134                 }
2135                 if ( $s === null ) {
2136                         return 'NULL';
2137                 } else {
2138                         # This will also quote numeric values. This should be harmless,
2139                         # and protects against weird problems that occur when they really
2140                         # _are_ strings such as article titles and string->number->string
2141                         # conversion is not 1:1.
2142                         return "'" . $this->strencode( $s ) . "'";
2143                 }
2144         }
2145
2146         /**
2147          * Quotes an identifier using `backticks` or "double quotes" depending on the database type.
2148          * MySQL uses `backticks` while basically everything else uses double quotes.
2149          * Since MySQL is the odd one out here the double quotes are our generic
2150          * and we implement backticks in DatabaseMysql.
2151          *
2152          * @param string $s
2153          * @return string
2154          */
2155         public function addIdentifierQuotes( $s ) {
2156                 return '"' . str_replace( '"', '""', $s ) . '"';
2157         }
2158
2159         /**
2160          * Returns if the given identifier looks quoted or not according to
2161          * the database convention for quoting identifiers .
2162          *
2163          * @note Do not use this to determine if untrusted input is safe.
2164          *   A malicious user can trick this function.
2165          * @param string $name
2166          * @return bool
2167          */
2168         public function isQuotedIdentifier( $name ) {
2169                 return $name[0] == '"' && substr( $name, -1, 1 ) == '"';
2170         }
2171
2172         /**
2173          * @param string $s
2174          * @return string
2175          */
2176         protected function escapeLikeInternal( $s ) {
2177                 return addcslashes( $s, '\%_' );
2178         }
2179
2180         public function buildLike() {
2181                 $params = func_get_args();
2182
2183                 if ( count( $params ) > 0 && is_array( $params[0] ) ) {
2184                         $params = $params[0];
2185                 }
2186
2187                 $s = '';
2188
2189                 foreach ( $params as $value ) {
2190                         if ( $value instanceof LikeMatch ) {
2191                                 $s .= $value->toString();
2192                         } else {
2193                                 $s .= $this->escapeLikeInternal( $value );
2194                         }
2195                 }
2196
2197                 return " LIKE {$this->addQuotes( $s )} ";
2198         }
2199
2200         public function anyChar() {
2201                 return new LikeMatch( '_' );
2202         }
2203
2204         public function anyString() {
2205                 return new LikeMatch( '%' );
2206         }
2207
2208         public function nextSequenceValue( $seqName ) {
2209                 return null;
2210         }
2211
2212         /**
2213          * USE INDEX clause. Unlikely to be useful for anything but MySQL. This
2214          * is only needed because a) MySQL must be as efficient as possible due to
2215          * its use on Wikipedia, and b) MySQL 4.0 is kind of dumb sometimes about
2216          * which index to pick. Anyway, other databases might have different
2217          * indexes on a given table. So don't bother overriding this unless you're
2218          * MySQL.
2219          * @param string $index
2220          * @return string
2221          */
2222         public function useIndexClause( $index ) {
2223                 return '';
2224         }
2225
2226         public function replace( $table, $uniqueIndexes, $rows, $fname = __METHOD__ ) {
2227                 $quotedTable = $this->tableName( $table );
2228
2229                 if ( count( $rows ) == 0 ) {
2230                         return;
2231                 }
2232
2233                 # Single row case
2234                 if ( !is_array( reset( $rows ) ) ) {
2235                         $rows = [ $rows ];
2236                 }
2237
2238                 // @FXIME: this is not atomic, but a trx would break affectedRows()
2239                 foreach ( $rows as $row ) {
2240                         # Delete rows which collide
2241                         if ( $uniqueIndexes ) {
2242                                 $sql = "DELETE FROM $quotedTable WHERE ";
2243                                 $first = true;
2244                                 foreach ( $uniqueIndexes as $index ) {
2245                                         if ( $first ) {
2246                                                 $first = false;
2247                                                 $sql .= '( ';
2248                                         } else {
2249                                                 $sql .= ' ) OR ( ';
2250                                         }
2251                                         if ( is_array( $index ) ) {
2252                                                 $first2 = true;
2253                                                 foreach ( $index as $col ) {
2254                                                         if ( $first2 ) {
2255                                                                 $first2 = false;
2256                                                         } else {
2257                                                                 $sql .= ' AND ';
2258                                                         }
2259                                                         $sql .= $col . '=' . $this->addQuotes( $row[$col] );
2260                                                 }
2261                                         } else {
2262                                                 $sql .= $index . '=' . $this->addQuotes( $row[$index] );
2263                                         }
2264                                 }
2265                                 $sql .= ' )';
2266                                 $this->query( $sql, $fname );
2267                         }
2268
2269                         # Now insert the row
2270                         $this->insert( $table, $row, $fname );
2271                 }
2272         }
2273
2274         /**
2275          * REPLACE query wrapper for MySQL and SQLite, which have a native REPLACE
2276          * statement.
2277          *
2278          * @param string $table Table name
2279          * @param array|string $rows Row(s) to insert
2280          * @param string $fname Caller function name
2281          *
2282          * @return ResultWrapper
2283          */
2284         protected function nativeReplace( $table, $rows, $fname ) {
2285                 $table = $this->tableName( $table );
2286
2287                 # Single row case
2288                 if ( !is_array( reset( $rows ) ) ) {
2289                         $rows = [ $rows ];
2290                 }
2291
2292                 $sql = "REPLACE INTO $table (" . implode( ',', array_keys( $rows[0] ) ) . ') VALUES ';
2293                 $first = true;
2294
2295                 foreach ( $rows as $row ) {
2296                         if ( $first ) {
2297                                 $first = false;
2298                         } else {
2299                                 $sql .= ',';
2300                         }
2301
2302                         $sql .= '(' . $this->makeList( $row ) . ')';
2303                 }
2304
2305                 return $this->query( $sql, $fname );
2306         }
2307
2308         public function upsert( $table, array $rows, array $uniqueIndexes, array $set,
2309                 $fname = __METHOD__
2310         ) {
2311                 if ( !count( $rows ) ) {
2312                         return true; // nothing to do
2313                 }
2314
2315                 if ( !is_array( reset( $rows ) ) ) {
2316                         $rows = [ $rows ];
2317                 }
2318
2319                 if ( count( $uniqueIndexes ) ) {
2320                         $clauses = []; // list WHERE clauses that each identify a single row
2321                         foreach ( $rows as $row ) {
2322                                 foreach ( $uniqueIndexes as $index ) {
2323                                         $index = is_array( $index ) ? $index : [ $index ]; // columns
2324                                         $rowKey = []; // unique key to this row
2325                                         foreach ( $index as $column ) {
2326                                                 $rowKey[$column] = $row[$column];
2327                                         }
2328                                         $clauses[] = $this->makeList( $rowKey, LIST_AND );
2329                                 }
2330                         }
2331                         $where = [ $this->makeList( $clauses, LIST_OR ) ];
2332                 } else {
2333                         $where = false;
2334                 }
2335
2336                 $useTrx = !$this->mTrxLevel;
2337                 if ( $useTrx ) {
2338                         $this->begin( $fname, self::TRANSACTION_INTERNAL );
2339                 }
2340                 try {
2341                         # Update any existing conflicting row(s)
2342                         if ( $where !== false ) {
2343                                 $ok = $this->update( $table, $set, $where, $fname );
2344                         } else {
2345                                 $ok = true;
2346                         }
2347                         # Now insert any non-conflicting row(s)
2348                         $ok = $this->insert( $table, $rows, $fname, [ 'IGNORE' ] ) && $ok;
2349                 } catch ( Exception $e ) {
2350                         if ( $useTrx ) {
2351                                 $this->rollback( $fname, self::FLUSHING_INTERNAL );
2352                         }
2353                         throw $e;
2354                 }
2355                 if ( $useTrx ) {
2356                         $this->commit( $fname, self::FLUSHING_INTERNAL );
2357                 }
2358
2359                 return $ok;
2360         }
2361
2362         public function deleteJoin( $delTable, $joinTable, $delVar, $joinVar, $conds,
2363                 $fname = __METHOD__
2364         ) {
2365                 if ( !$conds ) {
2366                         throw new DBUnexpectedError( $this,
2367                                 'DatabaseBase::deleteJoin() called with empty $conds' );
2368                 }
2369
2370                 $delTable = $this->tableName( $delTable );
2371                 $joinTable = $this->tableName( $joinTable );
2372                 $sql = "DELETE FROM $delTable WHERE $delVar IN (SELECT $joinVar FROM $joinTable ";
2373                 if ( $conds != '*' ) {
2374                         $sql .= 'WHERE ' . $this->makeList( $conds, LIST_AND );
2375                 }
2376                 $sql .= ')';
2377
2378                 $this->query( $sql, $fname );
2379         }
2380
2381         /**
2382          * Returns the size of a text field, or -1 for "unlimited"
2383          *
2384          * @param string $table
2385          * @param string $field
2386          * @return int
2387          */
2388         public function textFieldSize( $table, $field ) {
2389                 $table = $this->tableName( $table );
2390                 $sql = "SHOW COLUMNS FROM $table LIKE \"$field\";";
2391                 $res = $this->query( $sql, 'DatabaseBase::textFieldSize' );
2392                 $row = $this->fetchObject( $res );
2393
2394                 $m = [];
2395
2396                 if ( preg_match( '/\((.*)\)/', $row->Type, $m ) ) {
2397                         $size = $m[1];
2398                 } else {
2399                         $size = -1;
2400                 }
2401
2402                 return $size;
2403         }
2404
2405         /**
2406          * A string to insert into queries to show that they're low-priority, like
2407          * MySQL's LOW_PRIORITY. If no such feature exists, return an empty
2408          * string and nothing bad should happen.
2409          *
2410          * @return string Returns the text of the low priority option if it is
2411          *   supported, or a blank string otherwise
2412          */
2413         public function lowPriorityOption() {
2414                 return '';
2415         }
2416
2417         public function delete( $table, $conds, $fname = __METHOD__ ) {
2418                 if ( !$conds ) {
2419                         throw new DBUnexpectedError( $this, 'DatabaseBase::delete() called with no conditions' );
2420                 }
2421
2422                 $table = $this->tableName( $table );
2423                 $sql = "DELETE FROM $table";
2424
2425                 if ( $conds != '*' ) {
2426                         if ( is_array( $conds ) ) {
2427                                 $conds = $this->makeList( $conds, LIST_AND );
2428                         }
2429                         $sql .= ' WHERE ' . $conds;
2430                 }
2431
2432                 return $this->query( $sql, $fname );
2433         }
2434
2435         public function insertSelect(
2436                 $destTable, $srcTable, $varMap, $conds,
2437                 $fname = __METHOD__, $insertOptions = [], $selectOptions = []
2438         ) {
2439                 if ( $this->cliMode ) {
2440                         // For massive migrations with downtime, we don't want to select everything
2441                         // into memory and OOM, so do all this native on the server side if possible.
2442                         return $this->nativeInsertSelect(
2443                                 $destTable,
2444                                 $srcTable,
2445                                 $varMap,
2446                                 $conds,
2447                                 $fname,
2448                                 $insertOptions,
2449                                 $selectOptions
2450                         );
2451                 }
2452
2453                 // For web requests, do a locking SELECT and then INSERT. This puts the SELECT burden
2454                 // on only the master (without needing row-based-replication). It also makes it easy to
2455                 // know how big the INSERT is going to be.
2456                 $fields = [];
2457                 foreach ( $varMap as $dstColumn => $sourceColumnOrSql ) {
2458                         $fields[] = $this->fieldNameWithAlias( $sourceColumnOrSql, $dstColumn );
2459                 }
2460                 $selectOptions[] = 'FOR UPDATE';
2461                 $res = $this->select( $srcTable, implode( ',', $fields ), $conds, $fname, $selectOptions );
2462                 if ( !$res ) {
2463                         return false;
2464                 }
2465
2466                 $rows = [];
2467                 foreach ( $res as $row ) {
2468                         $rows[] = (array)$row;
2469                 }
2470
2471                 return $this->insert( $destTable, $rows, $fname, $insertOptions );
2472         }
2473
2474         public function nativeInsertSelect( $destTable, $srcTable, $varMap, $conds,
2475                 $fname = __METHOD__,
2476                 $insertOptions = [], $selectOptions = []
2477         ) {
2478                 $destTable = $this->tableName( $destTable );
2479
2480                 if ( !is_array( $insertOptions ) ) {
2481                         $insertOptions = [ $insertOptions ];
2482                 }
2483
2484                 $insertOptions = $this->makeInsertOptions( $insertOptions );
2485
2486                 if ( !is_array( $selectOptions ) ) {
2487                         $selectOptions = [ $selectOptions ];
2488                 }
2489
2490                 list( $startOpts, $useIndex, $tailOpts ) = $this->makeSelectOptions( $selectOptions );
2491
2492                 if ( is_array( $srcTable ) ) {
2493                         $srcTable = implode( ',', array_map( [ &$this, 'tableName' ], $srcTable ) );
2494                 } else {
2495                         $srcTable = $this->tableName( $srcTable );
2496                 }
2497
2498                 $sql = "INSERT $insertOptions INTO $destTable (" . implode( ',', array_keys( $varMap ) ) . ')' .
2499                         " SELECT $startOpts " . implode( ',', $varMap ) .
2500                         " FROM $srcTable $useIndex ";
2501
2502                 if ( $conds != '*' ) {
2503                         if ( is_array( $conds ) ) {
2504                                 $conds = $this->makeList( $conds, LIST_AND );
2505                         }
2506                         $sql .= " WHERE $conds";
2507                 }
2508
2509                 $sql .= " $tailOpts";
2510
2511                 return $this->query( $sql, $fname );
2512         }
2513
2514         /**
2515          * Construct a LIMIT query with optional offset. This is used for query
2516          * pages. The SQL should be adjusted so that only the first $limit rows
2517          * are returned. If $offset is provided as well, then the first $offset
2518          * rows should be discarded, and the next $limit rows should be returned.
2519          * If the result of the query is not ordered, then the rows to be returned
2520          * are theoretically arbitrary.
2521          *
2522          * $sql is expected to be a SELECT, if that makes a difference.
2523          *
2524          * The version provided by default works in MySQL and SQLite. It will very
2525          * likely need to be overridden for most other DBMSes.
2526          *
2527          * @param string $sql SQL query we will append the limit too
2528          * @param int $limit The SQL limit
2529          * @param int|bool $offset The SQL offset (default false)
2530          * @throws DBUnexpectedError
2531          * @return string
2532          */
2533         public function limitResult( $sql, $limit, $offset = false ) {
2534                 if ( !is_numeric( $limit ) ) {
2535                         throw new DBUnexpectedError( $this, "Invalid non-numeric limit passed to limitResult()\n" );
2536                 }
2537
2538                 return "$sql LIMIT "
2539                         . ( ( is_numeric( $offset ) && $offset != 0 ) ? "{$offset}," : "" )
2540                         . "{$limit} ";
2541         }
2542
2543         public function unionSupportsOrderAndLimit() {
2544                 return true; // True for almost every DB supported
2545         }
2546
2547         public function unionQueries( $sqls, $all ) {
2548                 $glue = $all ? ') UNION ALL (' : ') UNION (';
2549
2550                 return '(' . implode( $glue, $sqls ) . ')';
2551         }
2552
2553         public function conditional( $cond, $trueVal, $falseVal ) {
2554                 if ( is_array( $cond ) ) {
2555                         $cond = $this->makeList( $cond, LIST_AND );
2556                 }
2557
2558                 return " (CASE WHEN $cond THEN $trueVal ELSE $falseVal END) ";
2559         }
2560
2561         public function strreplace( $orig, $old, $new ) {
2562                 return "REPLACE({$orig}, {$old}, {$new})";
2563         }
2564
2565         public function getServerUptime() {
2566                 return 0;
2567         }
2568
2569         public function wasDeadlock() {
2570                 return false;
2571         }
2572
2573         public function wasLockTimeout() {
2574                 return false;
2575         }
2576
2577         public function wasErrorReissuable() {
2578                 return false;
2579         }
2580
2581         public function wasReadOnlyError() {
2582                 return false;
2583         }
2584
2585         /**
2586          * Determines if the given query error was a connection drop
2587          * STUB
2588          *
2589          * @param integer|string $errno
2590          * @return bool
2591          */
2592         public function wasConnectionError( $errno ) {
2593                 return false;
2594         }
2595
2596         /**
2597          * Perform a deadlock-prone transaction.
2598          *
2599          * This function invokes a callback function to perform a set of write
2600          * queries. If a deadlock occurs during the processing, the transaction
2601          * will be rolled back and the callback function will be called again.
2602          *
2603          * Avoid using this method outside of Job or Maintenance classes.
2604          *
2605          * Usage:
2606          *   $dbw->deadlockLoop( callback, ... );
2607          *
2608          * Extra arguments are passed through to the specified callback function.
2609          * This method requires that no transactions are already active to avoid
2610          * causing premature commits or exceptions.
2611          *
2612          * Returns whatever the callback function returned on its successful,
2613          * iteration, or false on error, for example if the retry limit was
2614          * reached.
2615          *
2616          * @return mixed
2617          * @throws DBUnexpectedError
2618          * @throws Exception
2619          */
2620         public function deadlockLoop() {
2621                 $args = func_get_args();
2622                 $function = array_shift( $args );
2623                 $tries = self::DEADLOCK_TRIES;
2624
2625                 $this->begin( __METHOD__ );
2626
2627                 $retVal = null;
2628                 /** @var Exception $e */
2629                 $e = null;
2630                 do {
2631                         try {
2632                                 $retVal = call_user_func_array( $function, $args );
2633                                 break;
2634                         } catch ( DBQueryError $e ) {
2635                                 if ( $this->wasDeadlock() ) {
2636                                         // Retry after a randomized delay
2637                                         usleep( mt_rand( self::DEADLOCK_DELAY_MIN, self::DEADLOCK_DELAY_MAX ) );
2638                                 } else {
2639                                         // Throw the error back up
2640                                         throw $e;
2641                                 }
2642                         }
2643                 } while ( --$tries > 0 );
2644
2645                 if ( $tries <= 0 ) {
2646                         // Too many deadlocks; give up
2647                         $this->rollback( __METHOD__ );
2648                         throw $e;
2649                 } else {
2650                         $this->commit( __METHOD__ );
2651
2652                         return $retVal;
2653                 }
2654         }
2655
2656         public function masterPosWait( DBMasterPos $pos, $timeout ) {
2657                 # Real waits are implemented in the subclass.
2658                 return 0;
2659         }
2660
2661         public function getSlavePos() {
2662                 # Stub
2663                 return false;
2664         }
2665
2666         public function getMasterPos() {
2667                 # Stub
2668                 return false;
2669         }
2670
2671         public function serverIsReadOnly() {
2672                 return false;
2673         }
2674
2675         final public function onTransactionResolution( callable $callback ) {
2676                 if ( !$this->mTrxLevel ) {
2677                         throw new DBUnexpectedError( $this, "No transaction is active." );
2678                 }
2679                 $this->mTrxEndCallbacks[] = [ $callback, wfGetCaller() ];
2680         }
2681
2682         final public function onTransactionIdle( callable $callback ) {
2683                 $this->mTrxIdleCallbacks[] = [ $callback, wfGetCaller() ];
2684                 if ( !$this->mTrxLevel ) {
2685                         $this->runOnTransactionIdleCallbacks( self::TRIGGER_IDLE );
2686                 }
2687         }
2688
2689         final public function onTransactionPreCommitOrIdle( callable $callback ) {
2690                 if ( $this->mTrxLevel ) {
2691                         $this->mTrxPreCommitCallbacks[] = [ $callback, wfGetCaller() ];
2692                 } else {
2693                         // If no transaction is active, then make one for this callback
2694                         $this->startAtomic( __METHOD__ );
2695                         try {
2696                                 call_user_func( $callback );
2697                                 $this->endAtomic( __METHOD__ );
2698                         } catch ( Exception $e ) {
2699                                 $this->rollback( __METHOD__, self::FLUSHING_INTERNAL );
2700                                 throw $e;
2701                         }
2702                 }
2703         }
2704
2705         final public function setTransactionListener( $name, callable $callback = null ) {
2706                 if ( $callback ) {
2707                         $this->mTrxRecurringCallbacks[$name] = [ $callback, wfGetCaller() ];
2708                 } else {
2709                         unset( $this->mTrxRecurringCallbacks[$name] );
2710                 }
2711         }
2712
2713         /**
2714          * Whether to disable running of post-COMMIT/ROLLBACK callbacks
2715          *
2716          * This method should not be used outside of Database/LoadBalancer
2717          *
2718          * @param bool $suppress
2719          * @since 1.28
2720          */
2721         final public function setTrxEndCallbackSuppression( $suppress ) {
2722                 $this->mTrxEndCallbacksSuppressed = $suppress;
2723         }
2724
2725         /**
2726          * Actually run and consume any "on transaction idle/resolution" callbacks.
2727          *
2728          * This method should not be used outside of Database/LoadBalancer
2729          *
2730          * @param integer $trigger IDatabase::TRIGGER_* constant
2731          * @since 1.20
2732          * @throws Exception
2733          */
2734         public function runOnTransactionIdleCallbacks( $trigger ) {
2735                 if ( $this->mTrxEndCallbacksSuppressed ) {
2736                         return;
2737                 }
2738
2739                 $autoTrx = $this->getFlag( DBO_TRX ); // automatic begin() enabled?
2740                 /** @var Exception $e */
2741                 $e = null; // first exception
2742                 do { // callbacks may add callbacks :)
2743                         $callbacks = array_merge(
2744                                 $this->mTrxIdleCallbacks,
2745                                 $this->mTrxEndCallbacks // include "transaction resolution" callbacks
2746                         );
2747                         $this->mTrxIdleCallbacks = []; // consumed (and recursion guard)
2748                         $this->mTrxEndCallbacks = []; // consumed (recursion guard)
2749                         foreach ( $callbacks as $callback ) {
2750                                 try {
2751                                         list( $phpCallback ) = $callback;
2752                                         $this->clearFlag( DBO_TRX ); // make each query its own transaction
2753                                         call_user_func_array( $phpCallback, [ $trigger ] );
2754                                         if ( $autoTrx ) {
2755                                                 $this->setFlag( DBO_TRX ); // restore automatic begin()
2756                                         } else {
2757                                                 $this->clearFlag( DBO_TRX ); // restore auto-commit
2758                                         }
2759                                 } catch ( Exception $ex ) {
2760                                         MWExceptionHandler::logException( $ex );
2761                                         $e = $e ?: $ex;
2762                                         // Some callbacks may use startAtomic/endAtomic, so make sure
2763                                         // their transactions are ended so other callbacks don't fail
2764                                         if ( $this->trxLevel() ) {
2765                                                 $this->rollback( __METHOD__, self::FLUSHING_INTERNAL );
2766                                         }
2767                                 }
2768                         }
2769                 } while ( count( $this->mTrxIdleCallbacks ) );
2770
2771                 if ( $e instanceof Exception ) {
2772                         throw $e; // re-throw any first exception
2773                 }
2774         }
2775
2776         /**
2777          * Actually run and consume any "on transaction pre-commit" callbacks.
2778          *
2779          * This method should not be used outside of Database/LoadBalancer
2780          *
2781          * @since 1.22
2782          * @throws Exception
2783          */
2784         public function runOnTransactionPreCommitCallbacks() {
2785                 $e = null; // first exception
2786                 do { // callbacks may add callbacks :)
2787                         $callbacks = $this->mTrxPreCommitCallbacks;
2788                         $this->mTrxPreCommitCallbacks = []; // consumed (and recursion guard)
2789                         foreach ( $callbacks as $callback ) {
2790                                 try {
2791                                         list( $phpCallback ) = $callback;
2792                                         call_user_func( $phpCallback );
2793                                 } catch ( Exception $ex ) {
2794                                         MWExceptionHandler::logException( $ex );
2795                                         $e = $e ?: $ex;
2796                                 }
2797                         }
2798                 } while ( count( $this->mTrxPreCommitCallbacks ) );
2799
2800                 if ( $e instanceof Exception ) {
2801                         throw $e; // re-throw any first exception
2802                 }
2803         }
2804
2805         /**
2806          * Actually run any "transaction listener" callbacks.
2807          *
2808          * This method should not be used outside of Database/LoadBalancer
2809          *
2810          * @param integer $trigger IDatabase::TRIGGER_* constant
2811          * @throws Exception
2812          * @since 1.20
2813          */
2814         public function runTransactionListenerCallbacks( $trigger ) {
2815                 if ( $this->mTrxEndCallbacksSuppressed ) {
2816                         return;
2817                 }
2818
2819                 /** @var Exception $e */
2820                 $e = null; // first exception
2821
2822                 foreach ( $this->mTrxRecurringCallbacks as $callback ) {
2823                         try {
2824                                 list( $phpCallback ) = $callback;
2825                                 $phpCallback( $trigger, $this );
2826                         } catch ( Exception $ex ) {
2827                                 MWExceptionHandler::logException( $ex );
2828                                 $e = $e ?: $ex;
2829                         }
2830                 }
2831
2832                 if ( $e instanceof Exception ) {
2833                         throw $e; // re-throw any first exception
2834                 }
2835         }
2836
2837         final public function startAtomic( $fname = __METHOD__ ) {
2838                 if ( !$this->mTrxLevel ) {
2839                         $this->begin( $fname, self::TRANSACTION_INTERNAL );
2840                         // If DBO_TRX is set, a series of startAtomic/endAtomic pairs will result
2841                         // in all changes being in one transaction to keep requests transactional.
2842                         if ( !$this->getFlag( DBO_TRX ) ) {
2843                                 $this->mTrxAutomaticAtomic = true;
2844                         }
2845                 }
2846
2847                 $this->mTrxAtomicLevels[] = $fname;
2848         }
2849
2850         final public function endAtomic( $fname = __METHOD__ ) {
2851                 if ( !$this->mTrxLevel ) {
2852                         throw new DBUnexpectedError( $this, "No atomic transaction is open (got $fname)." );
2853                 }
2854                 if ( !$this->mTrxAtomicLevels ||
2855                         array_pop( $this->mTrxAtomicLevels ) !== $fname
2856                 ) {
2857                         throw new DBUnexpectedError( $this, "Invalid atomic section ended (got $fname)." );
2858                 }
2859
2860                 if ( !$this->mTrxAtomicLevels && $this->mTrxAutomaticAtomic ) {
2861                         $this->commit( $fname, self::FLUSHING_INTERNAL );
2862                 }
2863         }
2864
2865         final public function doAtomicSection( $fname, callable $callback ) {
2866                 $this->startAtomic( $fname );
2867                 try {
2868                         $res = call_user_func_array( $callback, [ $this, $fname ] );
2869                 } catch ( Exception $e ) {
2870                         $this->rollback( $fname, self::FLUSHING_INTERNAL );
2871                         throw $e;
2872                 }
2873                 $this->endAtomic( $fname );
2874
2875                 return $res;
2876         }
2877
2878         final public function begin( $fname = __METHOD__, $mode = self::TRANSACTION_EXPLICIT ) {
2879                 // Protect against mismatched atomic section, transaction nesting, and snapshot loss
2880                 if ( $this->mTrxLevel ) {
2881                         if ( $this->mTrxAtomicLevels ) {
2882                                 $levels = implode( ', ', $this->mTrxAtomicLevels );
2883                                 $msg = "$fname: Got explicit BEGIN while atomic section(s) $levels are open.";
2884                                 throw new DBUnexpectedError( $this, $msg );
2885                         } elseif ( !$this->mTrxAutomatic ) {
2886                                 $msg = "$fname: Explicit transaction already active (from {$this->mTrxFname}).";
2887                                 throw new DBUnexpectedError( $this, $msg );
2888                         } else {
2889                                 // @TODO: make this an exception at some point
2890                                 $msg = "$fname: Implicit transaction already active (from {$this->mTrxFname}).";
2891                                 wfLogDBError( $msg );
2892                                 wfWarn( $msg );
2893                                 return; // join the main transaction set
2894                         }
2895                 } elseif ( $this->getFlag( DBO_TRX ) && $mode !== self::TRANSACTION_INTERNAL ) {
2896                         // @TODO: make this an exception at some point
2897                         $msg = "$fname: Implicit transaction expected (DBO_TRX set).";
2898                         wfLogDBError( $msg );
2899                         wfWarn( $msg );
2900                         return; // let any writes be in the main transaction
2901                 }
2902
2903                 // Avoid fatals if close() was called
2904                 $this->assertOpen();
2905
2906                 $this->doBegin( $fname );
2907                 $this->mTrxTimestamp = microtime( true );
2908                 $this->mTrxFname = $fname;
2909                 $this->mTrxDoneWrites = false;
2910                 $this->mTrxAutomatic = ( $mode === self::TRANSACTION_INTERNAL );
2911                 $this->mTrxAutomaticAtomic = false;
2912                 $this->mTrxAtomicLevels = [];
2913                 $this->mTrxShortId = wfRandomString( 12 );
2914                 $this->mTrxWriteDuration = 0.0;
2915                 $this->mTrxWriteQueryCount = 0;
2916                 $this->mTrxWriteAdjDuration = 0.0;
2917                 $this->mTrxWriteAdjQueryCount = 0;
2918                 $this->mTrxWriteCallers = [];
2919                 // First SELECT after BEGIN will establish the snapshot in REPEATABLE-READ.
2920                 // Get an estimate of the replica DB lag before then, treating estimate staleness
2921                 // as lag itself just to be safe
2922                 $status = $this->getApproximateLagStatus();
2923                 $this->mTrxSlaveLag = $status['lag'] + ( microtime( true ) - $status['since'] );
2924         }
2925
2926         /**
2927          * Issues the BEGIN command to the database server.
2928          *
2929          * @see DatabaseBase::begin()
2930          * @param string $fname
2931          */
2932         protected function doBegin( $fname ) {
2933                 $this->query( 'BEGIN', $fname );
2934                 $this->mTrxLevel = 1;
2935         }
2936
2937         final public function commit( $fname = __METHOD__, $flush = '' ) {
2938                 if ( $this->mTrxLevel && $this->mTrxAtomicLevels ) {
2939                         // There are still atomic sections open. This cannot be ignored
2940                         $levels = implode( ', ', $this->mTrxAtomicLevels );
2941                         throw new DBUnexpectedError(
2942                                 $this,
2943                                 "$fname: Got COMMIT while atomic sections $levels are still open."
2944                         );
2945                 }
2946
2947                 if ( $flush === self::FLUSHING_INTERNAL || $flush === self::FLUSHING_ALL_PEERS ) {
2948                         if ( !$this->mTrxLevel ) {
2949                                 return; // nothing to do
2950                         } elseif ( !$this->mTrxAutomatic ) {
2951                                 throw new DBUnexpectedError(
2952                                         $this,
2953                                         "$fname: Flushing an explicit transaction, getting out of sync."
2954                                 );
2955                         }
2956                 } else {
2957                         if ( !$this->mTrxLevel ) {
2958                                 wfWarn( "$fname: No transaction to commit, something got out of sync." );
2959                                 return; // nothing to do
2960                         } elseif ( $this->mTrxAutomatic ) {
2961                                 // @TODO: make this an exception at some point
2962                                 $msg = "$fname: Explicit commit of implicit transaction.";
2963                                 wfLogDBError( $msg );
2964                                 wfWarn( $msg );
2965                                 return; // wait for the main transaction set commit round
2966                         }
2967                 }
2968
2969                 // Avoid fatals if close() was called
2970                 $this->assertOpen();
2971
2972                 $this->runOnTransactionPreCommitCallbacks();
2973                 $writeTime = $this->pendingWriteQueryDuration();
2974                 $this->doCommit( $fname );
2975                 if ( $this->mTrxDoneWrites ) {
2976                         $this->mDoneWrites = microtime( true );
2977                         $this->getTransactionProfiler()->transactionWritingOut(
2978                                 $this->mServer, $this->mDBname, $this->mTrxShortId, $writeTime );
2979                 }
2980
2981                 $this->runOnTransactionIdleCallbacks( self::TRIGGER_COMMIT );
2982                 $this->runTransactionListenerCallbacks( self::TRIGGER_COMMIT );
2983         }
2984
2985         /**
2986          * Issues the COMMIT command to the database server.
2987          *
2988          * @see DatabaseBase::commit()
2989          * @param string $fname
2990          */
2991         protected function doCommit( $fname ) {
2992                 if ( $this->mTrxLevel ) {
2993                         $this->query( 'COMMIT', $fname );
2994                         $this->mTrxLevel = 0;
2995                 }
2996         }
2997
2998         final public function rollback( $fname = __METHOD__, $flush = '' ) {
2999                 if ( $flush === self::FLUSHING_INTERNAL || $flush === self::FLUSHING_ALL_PEERS ) {
3000                         if ( !$this->mTrxLevel ) {
3001                                 return; // nothing to do
3002                         }
3003                 } else {
3004                         if ( !$this->mTrxLevel ) {
3005                                 wfWarn( "$fname: No transaction to rollback, something got out of sync." );
3006                                 return; // nothing to do
3007                         } elseif ( $this->getFlag( DBO_TRX ) ) {
3008                                 throw new DBUnexpectedError(
3009                                         $this,
3010                                         "$fname: Expected mass rollback of all peer databases (DBO_TRX set)."
3011                                 );
3012                         }
3013                 }
3014
3015                 // Avoid fatals if close() was called
3016                 $this->assertOpen();
3017
3018                 $this->doRollback( $fname );
3019                 $this->mTrxAtomicLevels = [];
3020                 if ( $this->mTrxDoneWrites ) {
3021                         $this->getTransactionProfiler()->transactionWritingOut(
3022                                 $this->mServer, $this->mDBname, $this->mTrxShortId );
3023                 }
3024
3025                 $this->mTrxIdleCallbacks = []; // clear
3026                 $this->mTrxPreCommitCallbacks = []; // clear
3027                 $this->runOnTransactionIdleCallbacks( self::TRIGGER_ROLLBACK );
3028                 $this->runTransactionListenerCallbacks( self::TRIGGER_ROLLBACK );
3029         }
3030
3031         /**
3032          * Issues the ROLLBACK command to the database server.
3033          *
3034          * @see DatabaseBase::rollback()
3035          * @param string $fname
3036          */
3037         protected function doRollback( $fname ) {
3038                 if ( $this->mTrxLevel ) {
3039                         # Disconnects cause rollback anyway, so ignore those errors
3040                         $ignoreErrors = true;
3041                         $this->query( 'ROLLBACK', $fname, $ignoreErrors );
3042                         $this->mTrxLevel = 0;
3043                 }
3044         }
3045
3046         public function clearSnapshot( $fname = __METHOD__ ) {
3047                 if ( $this->writesOrCallbacksPending() || $this->explicitTrxActive() ) {
3048                         // This only flushes transactions to clear snapshots, not to write data
3049                         throw new DBUnexpectedError(
3050                                 $this,
3051                                 "$fname: Cannot COMMIT to clear snapshot because writes are pending."
3052                         );
3053                 }
3054
3055                 $this->commit( $fname, self::FLUSHING_INTERNAL );
3056         }
3057
3058         public function explicitTrxActive() {
3059                 return $this->mTrxLevel && ( $this->mTrxAtomicLevels || !$this->mTrxAutomatic );
3060         }
3061
3062         /**
3063          * Creates a new table with structure copied from existing table
3064          * Note that unlike most database abstraction functions, this function does not
3065          * automatically append database prefix, because it works at a lower
3066          * abstraction level.
3067          * The table names passed to this function shall not be quoted (this
3068          * function calls addIdentifierQuotes when needed).
3069          *
3070          * @param string $oldName Name of table whose structure should be copied
3071          * @param string $newName Name of table to be created
3072          * @param bool $temporary Whether the new table should be temporary
3073          * @param string $fname Calling function name
3074          * @throws MWException
3075          * @return bool True if operation was successful
3076          */
3077         public function duplicateTableStructure( $oldName, $newName, $temporary = false,
3078                 $fname = __METHOD__
3079         ) {
3080                 throw new MWException(
3081                         'DatabaseBase::duplicateTableStructure is not implemented in descendant class' );
3082         }
3083
3084         function listTables( $prefix = null, $fname = __METHOD__ ) {
3085                 throw new MWException( 'DatabaseBase::listTables is not implemented in descendant class' );
3086         }
3087
3088         /**
3089          * Reset the views process cache set by listViews()
3090          * @since 1.22
3091          */
3092         final public function clearViewsCache() {
3093                 $this->allViews = null;
3094         }
3095
3096         /**
3097          * Lists all the VIEWs in the database
3098          *
3099          * For caching purposes the list of all views should be stored in
3100          * $this->allViews. The process cache can be cleared with clearViewsCache()
3101          *
3102          * @param string $prefix Only show VIEWs with this prefix, eg. unit_test_
3103          * @param string $fname Name of calling function
3104          * @throws MWException
3105          * @return array
3106          * @since 1.22
3107          */
3108         public function listViews( $prefix = null, $fname = __METHOD__ ) {
3109                 throw new MWException( 'DatabaseBase::listViews is not implemented in descendant class' );
3110         }
3111
3112         /**
3113          * Differentiates between a TABLE and a VIEW
3114          *
3115          * @param string $name Name of the database-structure to test.
3116          * @throws MWException
3117          * @return bool
3118          * @since 1.22
3119          */
3120         public function isView( $name ) {
3121                 throw new MWException( 'DatabaseBase::isView is not implemented in descendant class' );
3122         }
3123
3124         public function timestamp( $ts = 0 ) {
3125                 return wfTimestamp( TS_MW, $ts );
3126         }
3127
3128         public function timestampOrNull( $ts = null ) {
3129                 if ( is_null( $ts ) ) {
3130                         return null;
3131                 } else {
3132                         return $this->timestamp( $ts );
3133                 }
3134         }
3135
3136         /**
3137          * Take the result from a query, and wrap it in a ResultWrapper if
3138          * necessary. Boolean values are passed through as is, to indicate success
3139          * of write queries or failure.
3140          *
3141          * Once upon a time, DatabaseBase::query() returned a bare MySQL result
3142          * resource, and it was necessary to call this function to convert it to
3143          * a wrapper. Nowadays, raw database objects are never exposed to external
3144          * callers, so this is unnecessary in external code.
3145          *
3146          * @param bool|ResultWrapper|resource|object $result
3147          * @return bool|ResultWrapper
3148          */
3149         protected function resultObject( $result ) {
3150                 if ( !$result ) {
3151                         return false;
3152                 } elseif ( $result instanceof ResultWrapper ) {
3153                         return $result;
3154                 } elseif ( $result === true ) {
3155                         // Successful write query
3156                         return $result;
3157                 } else {
3158                         return new ResultWrapper( $this, $result );
3159                 }
3160         }
3161
3162         public function ping( &$rtt = null ) {
3163                 // Avoid hitting the server if it was hit recently
3164                 if ( $this->isOpen() && ( microtime( true ) - $this->lastPing ) < self::PING_TTL ) {
3165                         if ( !func_num_args() || $this->mRTTEstimate > 0 ) {
3166                                 $rtt = $this->mRTTEstimate;
3167                                 return true; // don't care about $rtt
3168                         }
3169                 }
3170
3171                 // This will reconnect if possible or return false if not
3172                 $this->clearFlag( DBO_TRX, self::REMEMBER_PRIOR );
3173                 $ok = ( $this->query( self::PING_QUERY, __METHOD__, true ) !== false );
3174                 $this->restoreFlags( self::RESTORE_PRIOR );
3175
3176                 if ( $ok ) {
3177                         $rtt = $this->mRTTEstimate;
3178                 }
3179
3180                 return $ok;
3181         }
3182
3183         /**
3184          * @return bool
3185          */
3186         protected function reconnect() {
3187                 $this->closeConnection();
3188                 $this->mOpened = false;
3189                 $this->mConn = false;
3190                 try {
3191                         $this->open( $this->mServer, $this->mUser, $this->mPassword, $this->mDBname );
3192                         $this->lastPing = microtime( true );
3193                         $ok = true;
3194                 } catch ( DBConnectionError $e ) {
3195                         $ok = false;
3196                 }
3197
3198                 return $ok;
3199         }
3200
3201         public function getSessionLagStatus() {
3202                 return $this->getTransactionLagStatus() ?: $this->getApproximateLagStatus();
3203         }
3204
3205         /**
3206          * Get the replica DB lag when the current transaction started
3207          *
3208          * This is useful when transactions might use snapshot isolation
3209          * (e.g. REPEATABLE-READ in innodb), so the "real" lag of that data
3210          * is this lag plus transaction duration. If they don't, it is still
3211          * safe to be pessimistic. This returns null if there is no transaction.
3212          *
3213          * @return array|null ('lag': seconds or false on error, 'since': UNIX timestamp of BEGIN)
3214          * @since 1.27
3215          */
3216         public function getTransactionLagStatus() {
3217                 return $this->mTrxLevel
3218                         ? [ 'lag' => $this->mTrxSlaveLag, 'since' => $this->trxTimestamp() ]
3219                         : null;
3220         }
3221
3222         /**
3223          * Get a replica DB lag estimate for this server
3224          *
3225          * @return array ('lag': seconds or false on error, 'since': UNIX timestamp of estimate)
3226          * @since 1.27
3227          */
3228         public function getApproximateLagStatus() {
3229                 return [
3230                         'lag'   => $this->getLBInfo( 'slave' ) ? $this->getLag() : 0,
3231                         'since' => microtime( true )
3232                 ];
3233         }
3234
3235         /**
3236          * Merge the result of getSessionLagStatus() for several DBs
3237          * using the most pessimistic values to estimate the lag of
3238          * any data derived from them in combination
3239          *
3240          * This is information is useful for caching modules
3241          *
3242          * @see WANObjectCache::set()
3243          * @see WANObjectCache::getWithSetCallback()
3244          *
3245          * @param IDatabase $db1
3246          * @param IDatabase ...
3247          * @return array Map of values:
3248          *   - lag: highest lag of any of the DBs or false on error (e.g. replication stopped)
3249          *   - since: oldest UNIX timestamp of any of the DB lag estimates
3250          *   - pending: whether any of the DBs have uncommitted changes
3251          * @since 1.27
3252          */
3253         public static function getCacheSetOptions( IDatabase $db1 ) {
3254                 $res = [ 'lag' => 0, 'since' => INF, 'pending' => false ];
3255                 foreach ( func_get_args() as $db ) {
3256                         /** @var IDatabase $db */
3257                         $status = $db->getSessionLagStatus();
3258                         if ( $status['lag'] === false ) {
3259                                 $res['lag'] = false;
3260                         } elseif ( $res['lag'] !== false ) {
3261                                 $res['lag'] = max( $res['lag'], $status['lag'] );
3262                         }
3263                         $res['since'] = min( $res['since'], $status['since'] );
3264                         $res['pending'] = $res['pending'] ?: $db->writesPending();
3265                 }
3266
3267                 return $res;
3268         }
3269
3270         public function getLag() {
3271                 return 0;
3272         }
3273
3274         function maxListLen() {
3275                 return 0;
3276         }
3277
3278         public function encodeBlob( $b ) {
3279                 return $b;
3280         }
3281
3282         public function decodeBlob( $b ) {
3283                 if ( $b instanceof Blob ) {
3284                         $b = $b->fetch();
3285                 }
3286                 return $b;
3287         }
3288
3289         public function setSessionOptions( array $options ) {
3290         }
3291
3292         /**
3293          * Read and execute SQL commands from a file.
3294          *
3295          * Returns true on success, error string or exception on failure (depending
3296          * on object's error ignore settings).
3297          *
3298          * @param string $filename File name to open
3299          * @param bool|callable $lineCallback Optional function called before reading each line
3300          * @param bool|callable $resultCallback Optional function called for each MySQL result
3301          * @param bool|string $fname Calling function name or false if name should be
3302          *   generated dynamically using $filename
3303          * @param bool|callable $inputCallback Optional function called for each
3304          *   complete line sent
3305          * @throws Exception|MWException
3306          * @return bool|string
3307          */
3308         public function sourceFile(
3309                 $filename, $lineCallback = false, $resultCallback = false, $fname = false, $inputCallback = false
3310         ) {
3311                 MediaWiki\suppressWarnings();
3312                 $fp = fopen( $filename, 'r' );
3313                 MediaWiki\restoreWarnings();
3314
3315                 if ( false === $fp ) {
3316                         throw new MWException( "Could not open \"{$filename}\".\n" );
3317                 }
3318
3319                 if ( !$fname ) {
3320                         $fname = __METHOD__ . "( $filename )";
3321                 }
3322
3323                 try {
3324                         $error = $this->sourceStream( $fp, $lineCallback, $resultCallback, $fname, $inputCallback );
3325                 } catch ( Exception $e ) {
3326                         fclose( $fp );
3327                         throw $e;
3328                 }
3329
3330                 fclose( $fp );
3331
3332                 return $error;
3333         }
3334
3335         /**
3336          * Get the full path of a patch file. Originally based on archive()
3337          * from updaters.inc. Keep in mind this always returns a patch, as
3338          * it fails back to MySQL if no DB-specific patch can be found
3339          *
3340          * @param string $patch The name of the patch, like patch-something.sql
3341          * @return string Full path to patch file
3342          */
3343         public function patchPath( $patch ) {
3344                 global $IP;
3345
3346                 $dbType = $this->getType();
3347                 if ( file_exists( "$IP/maintenance/$dbType/archives/$patch" ) ) {
3348                         return "$IP/maintenance/$dbType/archives/$patch";
3349                 } else {
3350                         return "$IP/maintenance/archives/$patch";
3351                 }
3352         }
3353
3354         public function setSchemaVars( $vars ) {
3355                 $this->mSchemaVars = $vars;
3356         }
3357
3358         /**
3359          * Read and execute commands from an open file handle.
3360          *
3361          * Returns true on success, error string or exception on failure (depending
3362          * on object's error ignore settings).
3363          *
3364          * @param resource $fp File handle
3365          * @param bool|callable $lineCallback Optional function called before reading each query
3366          * @param bool|callable $resultCallback Optional function called for each MySQL result
3367          * @param string $fname Calling function name
3368          * @param bool|callable $inputCallback Optional function called for each complete query sent
3369          * @return bool|string
3370          */
3371         public function sourceStream( $fp, $lineCallback = false, $resultCallback = false,
3372                 $fname = __METHOD__, $inputCallback = false
3373         ) {
3374                 $cmd = '';
3375
3376                 while ( !feof( $fp ) ) {
3377                         if ( $lineCallback ) {
3378                                 call_user_func( $lineCallback );
3379                         }
3380
3381                         $line = trim( fgets( $fp ) );
3382
3383                         if ( $line == '' ) {
3384                                 continue;
3385                         }
3386
3387                         if ( '-' == $line[0] && '-' == $line[1] ) {
3388                                 continue;
3389                         }
3390
3391                         if ( $cmd != '' ) {
3392                                 $cmd .= ' ';
3393                         }
3394
3395                         $done = $this->streamStatementEnd( $cmd, $line );
3396
3397                         $cmd .= "$line\n";
3398
3399                         if ( $done || feof( $fp ) ) {
3400                                 $cmd = $this->replaceVars( $cmd );
3401
3402                                 if ( ( $inputCallback && call_user_func( $inputCallback, $cmd ) ) || !$inputCallback ) {
3403                                         $res = $this->query( $cmd, $fname );
3404
3405                                         if ( $resultCallback ) {
3406                                                 call_user_func( $resultCallback, $res, $this );
3407                                         }
3408
3409                                         if ( false === $res ) {
3410                                                 $err = $this->lastError();
3411
3412                                                 return "Query \"{$cmd}\" failed with error code \"$err\".\n";
3413                                         }
3414                                 }
3415                                 $cmd = '';
3416                         }
3417                 }
3418
3419                 return true;
3420         }
3421
3422         /**
3423          * Called by sourceStream() to check if we've reached a statement end
3424          *
3425          * @param string $sql SQL assembled so far
3426          * @param string $newLine New line about to be added to $sql
3427          * @return bool Whether $newLine contains end of the statement
3428          */
3429         public function streamStatementEnd( &$sql, &$newLine ) {
3430                 if ( $this->delimiter ) {
3431                         $prev = $newLine;
3432                         $newLine = preg_replace( '/' . preg_quote( $this->delimiter, '/' ) . '$/', '', $newLine );
3433                         if ( $newLine != $prev ) {
3434                                 return true;
3435                         }
3436                 }
3437
3438                 return false;
3439         }
3440
3441         /**
3442          * Database independent variable replacement. Replaces a set of variables
3443          * in an SQL statement with their contents as given by $this->getSchemaVars().
3444          *
3445          * Supports '{$var}' `{$var}` and / *$var* / (without the spaces) style variables.
3446          *
3447          * - '{$var}' should be used for text and is passed through the database's
3448          *   addQuotes method.
3449          * - `{$var}` should be used for identifiers (e.g. table and database names).
3450          *   It is passed through the database's addIdentifierQuotes method which
3451          *   can be overridden if the database uses something other than backticks.
3452          * - / *_* / or / *$wgDBprefix* / passes the name that follows through the
3453          *   database's tableName method.
3454          * - / *i* / passes the name that follows through the database's indexName method.
3455          * - In all other cases, / *$var* / is left unencoded. Except for table options,
3456          *   its use should be avoided. In 1.24 and older, string encoding was applied.
3457          *
3458          * @param string $ins SQL statement to replace variables in
3459          * @return string The new SQL statement with variables replaced
3460          */
3461         protected function replaceVars( $ins ) {
3462                 $vars = $this->getSchemaVars();
3463                 return preg_replace_callback(
3464                         '!
3465                                 /\* (\$wgDBprefix|[_i]) \*/ (\w*) | # 1-2. tableName, indexName
3466                                 \'\{\$ (\w+) }\'                  | # 3. addQuotes
3467                                 `\{\$ (\w+) }`                    | # 4. addIdentifierQuotes
3468                                 /\*\$ (\w+) \*/                     # 5. leave unencoded
3469                         !x',
3470                         function ( $m ) use ( $vars ) {
3471                                 // Note: Because of <https://bugs.php.net/bug.php?id=51881>,
3472                                 // check for both nonexistent keys *and* the empty string.
3473                                 if ( isset( $m[1] ) && $m[1] !== '' ) {
3474                                         if ( $m[1] === 'i' ) {
3475                                                 return $this->indexName( $m[2] );
3476                                         } else {
3477                                                 return $this->tableName( $m[2] );
3478                                         }
3479                                 } elseif ( isset( $m[3] ) && $m[3] !== '' && array_key_exists( $m[3], $vars ) ) {
3480                                         return $this->addQuotes( $vars[$m[3]] );
3481                                 } elseif ( isset( $m[4] ) && $m[4] !== '' && array_key_exists( $m[4], $vars ) ) {
3482                                         return $this->addIdentifierQuotes( $vars[$m[4]] );
3483                                 } elseif ( isset( $m[5] ) && $m[5] !== '' && array_key_exists( $m[5], $vars ) ) {
3484                                         return $vars[$m[5]];
3485                                 } else {
3486                                         return $m[0];
3487                                 }
3488                         },
3489                         $ins
3490                 );
3491         }
3492
3493         /**
3494          * Get schema variables. If none have been set via setSchemaVars(), then
3495          * use some defaults from the current object.
3496          *
3497          * @return array
3498          */
3499         protected function getSchemaVars() {
3500                 if ( $this->mSchemaVars ) {
3501                         return $this->mSchemaVars;
3502                 } else {
3503                         return $this->getDefaultSchemaVars();
3504                 }
3505         }
3506
3507         /**
3508          * Get schema variables to use if none have been set via setSchemaVars().
3509          *
3510          * Override this in derived classes to provide variables for tables.sql
3511          * and SQL patch files.
3512          *
3513          * @return array
3514          */
3515         protected function getDefaultSchemaVars() {
3516                 return [];
3517         }
3518
3519         public function lockIsFree( $lockName, $method ) {
3520                 return true;
3521         }
3522
3523         public function lock( $lockName, $method, $timeout = 5 ) {
3524                 $this->mNamedLocksHeld[$lockName] = 1;
3525
3526                 return true;
3527         }
3528
3529         public function unlock( $lockName, $method ) {
3530                 unset( $this->mNamedLocksHeld[$lockName] );
3531
3532                 return true;
3533         }
3534
3535         public function getScopedLockAndFlush( $lockKey, $fname, $timeout ) {
3536                 if ( $this->writesOrCallbacksPending() ) {
3537                         // This only flushes transactions to clear snapshots, not to write data
3538                         throw new DBUnexpectedError(
3539                                 $this,
3540                                 "$fname: Cannot COMMIT to clear snapshot because writes are pending."
3541                         );
3542                 }
3543
3544                 if ( !$this->lock( $lockKey, $fname, $timeout ) ) {
3545                         return null;
3546                 }
3547
3548                 $unlocker = new ScopedCallback( function () use ( $lockKey, $fname ) {
3549                         if ( $this->trxLevel() ) {
3550                                 // There is a good chance an exception was thrown, causing any early return
3551                                 // from the caller. Let any error handler get a chance to issue rollback().
3552                                 // If there isn't one, let the error bubble up and trigger server-side rollback.
3553                                 $this->onTransactionResolution( function () use ( $lockKey, $fname ) {
3554                                         $this->unlock( $lockKey, $fname );
3555                                 } );
3556                         } else {
3557                                 $this->unlock( $lockKey, $fname );
3558                         }
3559                 } );
3560
3561                 $this->commit( __METHOD__, self::FLUSHING_INTERNAL );
3562
3563                 return $unlocker;
3564         }
3565
3566         public function namedLocksEnqueue() {
3567                 return false;
3568         }
3569
3570         /**
3571          * Lock specific tables
3572          *
3573          * @param array $read Array of tables to lock for read access
3574          * @param array $write Array of tables to lock for write access
3575          * @param string $method Name of caller
3576          * @param bool $lowPriority Whether to indicate writes to be LOW PRIORITY
3577          * @return bool
3578          */
3579         public function lockTables( $read, $write, $method, $lowPriority = true ) {
3580                 return true;
3581         }
3582
3583         /**
3584          * Unlock specific tables
3585          *
3586          * @param string $method The caller
3587          * @return bool
3588          */
3589         public function unlockTables( $method ) {
3590                 return true;
3591         }
3592
3593         /**
3594          * Delete a table
3595          * @param string $tableName
3596          * @param string $fName
3597          * @return bool|ResultWrapper
3598          * @since 1.18
3599          */
3600         public function dropTable( $tableName, $fName = __METHOD__ ) {
3601                 if ( !$this->tableExists( $tableName, $fName ) ) {
3602                         return false;
3603                 }
3604                 $sql = "DROP TABLE " . $this->tableName( $tableName );
3605                 if ( $this->cascadingDeletes() ) {
3606                         $sql .= " CASCADE";
3607                 }
3608
3609                 return $this->query( $sql, $fName );
3610         }
3611
3612         /**
3613          * Get search engine class. All subclasses of this need to implement this
3614          * if they wish to use searching.
3615          *
3616          * @return string
3617          */
3618         public function getSearchEngine() {
3619                 return 'SearchEngineDummy';
3620         }
3621
3622         public function getInfinity() {
3623                 return 'infinity';
3624         }
3625
3626         public function encodeExpiry( $expiry ) {
3627                 return ( $expiry == '' || $expiry == 'infinity' || $expiry == $this->getInfinity() )
3628                         ? $this->getInfinity()
3629                         : $this->timestamp( $expiry );
3630         }
3631
3632         public function decodeExpiry( $expiry, $format = TS_MW ) {
3633                 return ( $expiry == '' || $expiry == 'infinity' || $expiry == $this->getInfinity() )
3634                         ? 'infinity'
3635                         : wfTimestamp( $format, $expiry );
3636         }
3637
3638         public function setBigSelects( $value = true ) {
3639                 // no-op
3640         }
3641
3642         public function isReadOnly() {
3643                 return ( $this->getReadOnlyReason() !== false );
3644         }
3645
3646         /**
3647          * @return string|bool Reason this DB is read-only or false if it is not
3648          */
3649         protected function getReadOnlyReason() {
3650                 $reason = $this->getLBInfo( 'readOnlyReason' );
3651
3652                 return is_string( $reason ) ? $reason : false;
3653         }
3654
3655         /**
3656          * @since 1.19
3657          * @return string
3658          */
3659         public function __toString() {
3660                 return (string)$this->mConn;
3661         }
3662
3663         /**
3664          * Run a few simple sanity checks
3665          */
3666         public function __destruct() {
3667                 if ( $this->mTrxLevel && $this->mTrxDoneWrites ) {
3668                         trigger_error( "Uncommitted DB writes (transaction from {$this->mTrxFname})." );
3669                 }
3670                 $danglingCallbacks = array_merge(
3671                         $this->mTrxIdleCallbacks,
3672                         $this->mTrxPreCommitCallbacks,
3673                         $this->mTrxEndCallbacks
3674                 );
3675                 if ( $danglingCallbacks ) {
3676                         $callers = [];
3677                         foreach ( $danglingCallbacks as $callbackInfo ) {
3678                                 $callers[] = $callbackInfo[1];
3679                         }
3680                         $callers = implode( ', ', $callers );
3681                         trigger_error( "DB transaction callbacks still pending (from $callers)." );
3682                 }
3683         }
3684 }
3685
3686 /**
3687  * @since 1.27
3688  */
3689 abstract class Database extends DatabaseBase {
3690         // B/C until nothing type hints for DatabaseBase
3691         // @TODO: finish renaming DatabaseBase => Database
3692 }