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