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