includes/db/Database.php

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