includes/db/Database.php

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