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 Whether this PHP instance is for a CLI script */
  66         protected $cliMode;
  67         /** @var string Agent name for query profiling */
  68         protected $agent;
  69
  70         /** @var BagOStuff APC cache */
  71         protected $srvCache;
  72         /** @var LoggerInterface */
  73         protected $connLogger;
  74         /** @var LoggerInterface */
  75         protected $queryLogger;
  76         /** @var callback Error logging callback */
  77         protected $errorLogger;
  78
  79         /** @var resource Database connection */
  80         protected $mConn = null;
  81         /** @var bool */
  82         protected $mOpened = false;
  83
  84         /** @var array[] List of (callable, method name) */
  85         protected $mTrxIdleCallbacks = [];
  86         /** @var array[] List of (callable, method name) */
  87         protected $mTrxPreCommitCallbacks = [];
  88         /** @var array[] List of (callable, method name) */
  89         protected $mTrxEndCallbacks = [];
  90         /** @var callable[] Map of (name => callable) */
  91         protected $mTrxRecurringCallbacks = [];
  92         /** @var bool Whether to suppress triggering of transaction end callbacks */
  93         protected $mTrxEndCallbacksSuppressed = false;
  94
  95         /** @var string */
  96         protected $mTablePrefix;
  97         /** @var string */
  98         protected $mSchema;
  99         /** @var integer */
 100         protected $mFlags;
 101         /** @var array */
 102         protected $mLBInfo = [];
 103         /** @var bool|null */
 104         protected $mDefaultBigSelects = null;
 105         /** @var array|bool */
 106         protected $mSchemaVars = false;
 107         /** @var array */
 108         protected $mSessionVars = [];
 109         /** @var array|null */
 110         protected $preparedArgs;
 111         /** @var string|bool|null Stashed value of html_errors INI setting */
 112         protected $htmlErrors;
 113         /** @var string */
 114         protected $delimiter = ';';
 115
 116         /**
 117          * Either 1 if a transaction is active or 0 otherwise.
 118          * The other Trx fields may not be meaningfull if this is 0.
 119          *
 120          * @var int
 121          */
 122         protected $mTrxLevel = 0;
 123         /**
 124          * Either a short hexidecimal string if a transaction is active or ""
 125          *
 126          * @var string
 127          * @see DatabaseBase::mTrxLevel
 128          */
 129         protected $mTrxShortId = '';
 130         /**
 131          * The UNIX time that the transaction started. Callers can assume that if
 132          * snapshot isolation is used, then the data is *at least* up to date to that
 133          * point (possibly more up-to-date since the first SELECT defines the snapshot).
 134          *
 135          * @var float|null
 136          * @see DatabaseBase::mTrxLevel
 137          */
 138         private $mTrxTimestamp = null;
 139         /** @var float Lag estimate at the time of BEGIN */
 140         private $mTrxReplicaLag = null;
 141         /**
 142          * Remembers the function name given for starting the most recent transaction via begin().
 143          * Used to provide additional context for error reporting.
 144          *
 145          * @var string
 146          * @see DatabaseBase::mTrxLevel
 147          */
 148         private $mTrxFname = null;
 149         /**
 150          * Record if possible write queries were done in the last transaction started
 151          *
 152          * @var bool
 153          * @see DatabaseBase::mTrxLevel
 154          */
 155         private $mTrxDoneWrites = false;
 156         /**
 157          * Record if the current transaction was started implicitly due to DBO_TRX being set.
 158          *
 159          * @var bool
 160          * @see DatabaseBase::mTrxLevel
 161          */
 162         private $mTrxAutomatic = false;
 163         /**
 164          * Array of levels of atomicity within transactions
 165          *
 166          * @var array
 167          */
 168         private $mTrxAtomicLevels = [];
 169         /**
 170          * Record if the current transaction was started implicitly by DatabaseBase::startAtomic
 171          *
 172          * @var bool
 173          */
 174         private $mTrxAutomaticAtomic = false;
 175         /**
 176          * Track the write query callers of the current transaction
 177          *
 178          * @var string[]
 179          */
 180         private $mTrxWriteCallers = [];
 181         /**
 182          * @var float Seconds spent in write queries for the current transaction
 183          */
 184         private $mTrxWriteDuration = 0.0;
 185         /**
 186          * @var integer Number of write queries for the current transaction
 187          */
 188         private $mTrxWriteQueryCount = 0;
 189         /**
 190          * @var float Like mTrxWriteQueryCount but excludes lock-bound, easy to replicate, queries
 191          */
 192         private $mTrxWriteAdjDuration = 0.0;
 193         /**
 194          * @var integer Number of write queries counted in mTrxWriteAdjDuration
 195          */
 196         private $mTrxWriteAdjQueryCount = 0;
 197         /**
 198          * @var float RTT time estimate
 199          */
 200         private $mRTTEstimate = 0.0;
 201
 202         /** @var array Map of (name => 1) for locks obtained via lock() */
 203         private $mNamedLocksHeld = [];
 204
 205         /** @var IDatabase|null Lazy handle to the master DB this server replicates from */
 206         private $lazyMasterHandle;
 207
 208         /**
 209          * @since 1.21
 210          * @var resource File handle for upgrade
 211          */
 212         protected $fileHandle = null;
 213
 214         /**
 215          * @since 1.22
 216          * @var string[] Process cache of VIEWs names in the database
 217          */
 218         protected $allViews = null;
 219
 220         /** @var float UNIX timestamp */
 221         protected $lastPing = 0.0;
 222
 223         /** @var int[] Prior mFlags values */
 224         private $priorFlags = [];
 225
 226         /** @var Profiler */
 227         protected $profiler;
 228         /** @var TransactionProfiler */
 229         protected $trxProfiler;
 230
 231         /**
 232          * Constructor.
 233          *
 234          * FIXME: It is possible to construct a Database object with no associated
 235          * connection object, by specifying no parameters to __construct(). This
 236          * feature is deprecated and should be removed.
 237          *
 238          * IDatabase classes should not be constructed directly in external
 239          * code. DatabaseBase::factory() should be used instead.
 240          *
 241          * @param array $params Parameters passed from DatabaseBase::factory()
 242          */
 243         function __construct( array $params ) {
 244                 $server = $params['host'];
 245                 $user = $params['user'];
 246                 $password = $params['password'];
 247                 $dbName = $params['dbname'];
 248                 $flags = $params['flags'];
 249
 250                 $this->mSchema = $params['schema'];
 251                 $this->mTablePrefix = $params['tablePrefix'];
 252
 253                 $this->cliMode = isset( $params['cliMode'] )
 254                         ? $params['cliMode']
 255                         : ( PHP_SAPI === 'cli' );
 256                 $this->agent = isset( $params['agent'] )
 257                         ? str_replace( '/', '-', $params['agent'] ) // escape for comment
 258                         : '';
 259
 260                 $this->mFlags = $flags;
 261                 if ( $this->mFlags & DBO_DEFAULT ) {
 262                         if ( $this->cliMode ) {
 263                                 $this->mFlags &= ~DBO_TRX;
 264                         } else {
 265                                 $this->mFlags |= DBO_TRX;
 266                         }
 267                 }
 268
 269                 $this->mSessionVars = $params['variables'];
 270
 271                 $this->srvCache = isset( $params['srvCache'] )
 272                         ? $params['srvCache']
 273                         : new HashBagOStuff();
 274
 275                 $this->profiler = isset( $params['profiler'] )
 276                         ? $params['profiler']
 277                         : Profiler::instance(); // @TODO: remove global state
 278                 $this->trxProfiler = isset( $params['trxProfiler'] )
 279                         ? $params['trxProfiler']
 280                         : new TransactionProfiler();
 281                 $this->connLogger = isset( $params['connLogger'] )
 282                         ? $params['connLogger']
 283                         : new \Psr\Log\NullLogger();
 284                 $this->queryLogger = isset( $params['queryLogger'] )
 285                         ? $params['queryLogger']
 286                         : new \Psr\Log\NullLogger();
 287
 288                 if ( $user ) {
 289                         $this->open( $server, $user, $password, $dbName );
 290                 }
 291         }
 292
 293         /**
 294          * Given a DB type, construct the name of the appropriate child class of
 295          * IDatabase. This is designed to replace all of the manual stuff like:
 296          *    $class = 'Database' . ucfirst( strtolower( $dbType ) );
 297          * as well as validate against the canonical list of DB types we have
 298          *
 299          * This factory function is mostly useful for when you need to connect to a
 300          * database other than the MediaWiki default (such as for external auth,
 301          * an extension, et cetera). Do not use this to connect to the MediaWiki
 302          * database. Example uses in core:
 303          * @see LoadBalancer::reallyOpenConnection()
 304          * @see ForeignDBRepo::getMasterDB()
 305          * @see WebInstallerDBConnect::execute()
 306          *
 307          * @since 1.18
 308          *
 309          * @param string $dbType A possible DB type
 310          * @param array $p An array of options to pass to the constructor.
 311          *    Valid options are: host, user, password, dbname, flags, tablePrefix, schema, driver
 312          * @return IDatabase|null If the database driver or extension cannot be found
 313          * @throws InvalidArgumentException If the database driver or extension cannot be found
 314          */
 315         final public static function factory( $dbType, $p = [] ) {
 316                 $canonicalDBTypes = [
 317                         'mysql' => [ 'mysqli', 'mysql' ],
 318                         'postgres' => [],
 319                         'sqlite' => [],
 320                         'oracle' => [],
 321                         'mssql' => [],
 322                 ];
 323
 324                 $driver = false;
 325                 $dbType = strtolower( $dbType );
 326                 if ( isset( $canonicalDBTypes[$dbType] ) && $canonicalDBTypes[$dbType] ) {
 327                         $possibleDrivers = $canonicalDBTypes[$dbType];
 328                         if ( !empty( $p['driver'] ) ) {
 329                                 if ( in_array( $p['driver'], $possibleDrivers ) ) {
 330                                         $driver = $p['driver'];
 331                                 } else {
 332                                         throw new InvalidArgumentException( __METHOD__ .
 333                                                 " type '$dbType' does not support driver '{$p['driver']}'" );
 334                                 }
 335                         } else {
 336                                 foreach ( $possibleDrivers as $posDriver ) {
 337                                         if ( extension_loaded( $posDriver ) ) {
 338                                                 $driver = $posDriver;
 339                                                 break;
 340                                         }
 341                                 }
 342                         }
 343                 } else {
 344                         $driver = $dbType;
 345                 }
 346                 if ( $driver === false ) {
 347                         throw new InvalidArgumentException( __METHOD__ .
 348                                 " no viable database extension found for type '$dbType'" );
 349                 }
 350
 351                 // Determine schema defaults. Currently Microsoft SQL Server uses $wgDBmwschema,
 352                 // and everything else doesn't use a schema (e.g. null)
 353                 // Although postgres and oracle support schemas, we don't use them (yet)
 354                 // to maintain backwards compatibility
 355                 $defaultSchemas = [
 356                         'mssql' => 'get from global',
 357                 ];
 358
 359                 $class = 'Database' . ucfirst( $driver );
 360                 if ( class_exists( $class ) && is_subclass_of( $class, 'IDatabase' ) ) {
 361                         // Resolve some defaults for b/c
 362                         $p['host'] = isset( $p['host'] ) ? $p['host'] : false;
 363                         $p['user'] = isset( $p['user'] ) ? $p['user'] : false;
 364                         $p['password'] = isset( $p['password'] ) ? $p['password'] : false;
 365                         $p['dbname'] = isset( $p['dbname'] ) ? $p['dbname'] : false;
 366                         $p['flags'] = isset( $p['flags'] ) ? $p['flags'] : 0;
 367                         $p['variables'] = isset( $p['variables'] ) ? $p['variables'] : [];
 368                         $p['tablePrefix'] = isset( $p['tablePrefix'] ) ? $p['tablePrefix'] : '';
 369                         if ( !isset( $p['schema'] ) ) {
 370                                 $p['schema'] = isset( $defaultSchemas[$dbType] ) ? $defaultSchemas[$dbType] : null;
 371                         }
 372                         $p['foreign'] = isset( $p['foreign'] ) ? $p['foreign'] : false;
 373
 374                         $conn = new $class( $p );
 375                         if ( isset( $p['connLogger'] ) ) {
 376                                 $conn->connLogger = $p['connLogger'];
 377                         }
 378                         if ( isset( $p['queryLogger'] ) ) {
 379                                 $conn->queryLogger = $p['queryLogger'];
 380                         }
 381                         if ( isset( $p['errorLogger'] ) ) {
 382                                 $conn->errorLogger = $p['errorLogger'];
 383                         } else {
 384                                 $conn->errorLogger = function ( Exception $e ) {
 385                                         trigger_error( get_class( $e ) . ': ' . $e->getMessage(), E_WARNING );
 386                                 };
 387                         }
 388                 } else {
 389                         $conn = null;
 390                 }
 391
 392                 return $conn;
 393         }
 394
 395         public function setLogger( LoggerInterface $logger ) {
 396                 $this->queryLogger = $logger;
 397         }
 398
 399         public function getServerInfo() {
 400                 return $this->getServerVersion();
 401         }
 402
 403         /**
 404          * @return string Command delimiter used by this database engine
 405          */
 406         public function getDelimiter() {
 407                 return $this->delimiter;
 408         }
 409
 410         /**
 411          * Boolean, controls output of large amounts of debug information.
 412          * @param bool|null $debug
 413          *   - true to enable debugging
 414          *   - false to disable debugging
 415          *   - omitted or null to do nothing
 416          *
 417          * @return bool Previous value of the flag
 418          * @deprecated since 1.28; use setFlag()
 419          */
 420         public function debug( $debug = null ) {
 421                 $res = $this->getFlag( DBO_DEBUG );
 422                 if ( $debug !== null ) {
 423                         $debug ? $this->setFlag( DBO_DEBUG ) : $this->clearFlag( DBO_DEBUG );
 424                 }
 425
 426                 return $res;
 427         }
 428
 429         public function bufferResults( $buffer = null ) {
 430                 $res = !$this->getFlag( DBO_NOBUFFER );
 431                 if ( $buffer !== null ) {
 432                         $buffer ? $this->clearFlag( DBO_NOBUFFER ) : $this->setFlag( DBO_NOBUFFER );
 433                 }
 434
 435                 return $res;
 436         }
 437
 438         /**
 439          * Turns on (false) or off (true) the automatic generation and sending
 440          * of a "we're sorry, but there has been a database error" page on
 441          * database errors. Default is on (false). When turned off, the
 442          * code should use lastErrno() and lastError() to handle the
 443          * situation as appropriate.
 444          *
 445          * Do not use this function outside of the Database classes.
 446          *
 447          * @param null|bool $ignoreErrors
 448          * @return bool The previous value of the flag.
 449          */
 450         protected function ignoreErrors( $ignoreErrors = null ) {
 451                 $res = $this->getFlag( DBO_IGNORE );
 452                 if ( $ignoreErrors !== null ) {
 453                         $ignoreErrors ? $this->setFlag( DBO_IGNORE ) : $this->clearFlag( DBO_IGNORE );
 454                 }
 455
 456                 return $res;
 457         }
 458
 459         public function trxLevel() {
 460                 return $this->mTrxLevel;
 461         }
 462
 463         public function trxTimestamp() {
 464                 return $this->mTrxLevel ? $this->mTrxTimestamp : null;
 465         }
 466
 467         public function tablePrefix( $prefix = null ) {
 468                 $old = $this->mTablePrefix;
 469                 $this->mTablePrefix = $prefix;
 470
 471                 return $old;
 472         }
 473
 474         public function dbSchema( $schema = null ) {
 475                 $old = $this->mSchema;
 476                 $this->mSchema = $schema;
 477
 478                 return $old;
 479         }
 480
 481         /**
 482          * Set the filehandle to copy write statements to.
 483          *
 484          * @param resource $fh File handle
 485          */
 486         public function setFileHandle( $fh ) {
 487                 $this->fileHandle = $fh;
 488         }
 489
 490         public function getLBInfo( $name = null ) {
 491                 if ( is_null( $name ) ) {
 492                         return $this->mLBInfo;
 493                 } else {
 494                         if ( array_key_exists( $name, $this->mLBInfo ) ) {
 495                                 return $this->mLBInfo[$name];
 496                         } else {
 497                                 return null;
 498                         }
 499                 }
 500         }
 501
 502         public function setLBInfo( $name, $value = null ) {
 503                 if ( is_null( $value ) ) {
 504                         $this->mLBInfo = $name;
 505                 } else {
 506                         $this->mLBInfo[$name] = $value;
 507                 }
 508         }
 509
 510         public function setLazyMasterHandle( IDatabase $conn ) {
 511                 $this->lazyMasterHandle = $conn;
 512         }
 513
 514         /**
 515          * @return IDatabase|null
 516          * @see setLazyMasterHandle()
 517          * @since 1.27
 518          */
 519         public function getLazyMasterHandle() {
 520                 return $this->lazyMasterHandle;
 521         }
 522
 523         /**
 524          * @param TransactionProfiler $profiler
 525          * @since 1.27
 526          */
 527         public function setTransactionProfiler( TransactionProfiler $profiler ) {
 528                 $this->trxProfiler = $profiler;
 529         }
 530
 531         /**
 532          * Returns true if this database supports (and uses) cascading deletes
 533          *
 534          * @return bool
 535          */
 536         public function cascadingDeletes() {
 537                 return false;
 538         }
 539
 540         /**
 541          * Returns true if this database supports (and uses) triggers (e.g. on the page table)
 542          *
 543          * @return bool
 544          */
 545         public function cleanupTriggers() {
 546                 return false;
 547         }
 548
 549         /**
 550          * Returns true if this database is strict about what can be put into an IP field.
 551          * Specifically, it uses a NULL value instead of an empty string.
 552          *
 553          * @return bool
 554          */
 555         public function strictIPs() {
 556                 return false;
 557         }
 558
 559         /**
 560          * Returns true if this database uses timestamps rather than integers
 561          *
 562          * @return bool
 563          */
 564         public function realTimestamps() {
 565                 return false;
 566         }
 567
 568         public function implicitGroupby() {
 569                 return true;
 570         }
 571
 572         public function implicitOrderby() {
 573                 return true;
 574         }
 575
 576         /**
 577          * Returns true if this database can do a native search on IP columns
 578          * e.g. this works as expected: .. WHERE rc_ip = '127.42.12.102/32';
 579          *
 580          * @return bool
 581          */
 582         public function searchableIPs() {
 583                 return false;
 584         }
 585
 586         /**
 587          * Returns true if this database can use functional indexes
 588          *
 589          * @return bool
 590          */
 591         public function functionalIndexes() {
 592                 return false;
 593         }
 594
 595         public function lastQuery() {
 596                 return $this->mLastQuery;
 597         }
 598
 599         public function doneWrites() {
 600                 return (bool)$this->mDoneWrites;
 601         }
 602
 603         public function lastDoneWrites() {
 604                 return $this->mDoneWrites ?: false;
 605         }
 606
 607         public function writesPending() {
 608                 return $this->mTrxLevel && $this->mTrxDoneWrites;
 609         }
 610
 611         public function writesOrCallbacksPending() {
 612                 return $this->mTrxLevel && (
 613                         $this->mTrxDoneWrites || $this->mTrxIdleCallbacks || $this->mTrxPreCommitCallbacks
 614                 );
 615         }
 616
 617         public function pendingWriteQueryDuration( $type = self::ESTIMATE_TOTAL ) {
 618                 if ( !$this->mTrxLevel ) {
 619                         return false;
 620                 } elseif ( !$this->mTrxDoneWrites ) {
 621                         return 0.0;
 622                 }
 623
 624                 switch ( $type ) {
 625                         case self::ESTIMATE_DB_APPLY:
 626                                 $this->ping( $rtt );
 627                                 $rttAdjTotal = $this->mTrxWriteAdjQueryCount * $rtt;
 628                                 $applyTime = max( $this->mTrxWriteAdjDuration - $rttAdjTotal, 0 );
 629                                 // For omitted queries, make them count as something at least
 630                                 $omitted = $this->mTrxWriteQueryCount - $this->mTrxWriteAdjQueryCount;
 631                                 $applyTime += self::TINY_WRITE_SEC * $omitted;
 632
 633                                 return $applyTime;
 634                         default: // everything
 635                                 return $this->mTrxWriteDuration;
 636                 }
 637         }
 638
 639         public function pendingWriteCallers() {
 640                 return $this->mTrxLevel ? $this->mTrxWriteCallers : [];
 641         }
 642
 643         protected function pendingWriteAndCallbackCallers() {
 644                 if ( !$this->mTrxLevel ) {
 645                         return [];
 646                 }
 647
 648                 $fnames = $this->mTrxWriteCallers;
 649                 foreach ( [
 650                         $this->mTrxIdleCallbacks,
 651                         $this->mTrxPreCommitCallbacks,
 652                         $this->mTrxEndCallbacks
 653                 ] as $callbacks ) {
 654                         foreach ( $callbacks as $callback ) {
 655                                 $fnames[] = $callback[1];
 656                         }
 657                 }
 658
 659                 return $fnames;
 660         }
 661
 662         public function isOpen() {
 663                 return $this->mOpened;
 664         }
 665
 666         public function setFlag( $flag, $remember = self::REMEMBER_NOTHING ) {
 667                 if ( $remember === self::REMEMBER_PRIOR ) {
 668                         array_push( $this->priorFlags, $this->mFlags );
 669                 }
 670                 $this->mFlags |= $flag;
 671         }
 672
 673         public function clearFlag( $flag, $remember = self::REMEMBER_NOTHING ) {
 674                 if ( $remember === self::REMEMBER_PRIOR ) {
 675                         array_push( $this->priorFlags, $this->mFlags );
 676                 }
 677                 $this->mFlags &= ~$flag;
 678         }
 679
 680         public function restoreFlags( $state = self::RESTORE_PRIOR ) {
 681                 if ( !$this->priorFlags ) {
 682                         return;
 683                 }
 684
 685                 if ( $state === self::RESTORE_INITIAL ) {
 686                         $this->mFlags = reset( $this->priorFlags );
 687                         $this->priorFlags = [];
 688                 } else {
 689                         $this->mFlags = array_pop( $this->priorFlags );
 690                 }
 691         }
 692
 693         public function getFlag( $flag ) {
 694                 return !!( $this->mFlags & $flag );
 695         }
 696
 697         public function getProperty( $name ) {
 698                 return $this->$name;
 699         }
 700
 701         public function getWikiID() {
 702                 if ( $this->mTablePrefix ) {
 703                         return "{$this->mDBname}-{$this->mTablePrefix}";
 704                 } else {
 705                         return $this->mDBname;
 706                 }
 707         }
 708
 709         /**
 710          * Get information about an index into an object
 711          * @param string $table Table name
 712          * @param string $index Index name
 713          * @param string $fname Calling function name
 714          * @return mixed Database-specific index description class or false if the index does not exist
 715          */
 716         abstract function indexInfo( $table, $index, $fname = __METHOD__ );
 717
 718         /**
 719          * Wrapper for addslashes()
 720          *
 721          * @param string $s String to be slashed.
 722          * @return string Slashed string.
 723          */
 724         abstract function strencode( $s );
 725
 726         /**
 727          * Called by serialize. Throw an exception when DB connection is serialized.
 728          * This causes problems on some database engines because the connection is
 729          * not restored on unserialize.
 730          */
 731         public function __sleep() {
 732                 throw new RuntimeException( 'Database serialization may cause problems, since ' .
 733                         'the connection is not restored on wakeup.' );
 734         }
 735
 736         protected function installErrorHandler() {
 737                 $this->mPHPError = false;
 738                 $this->htmlErrors = ini_set( 'html_errors', '0' );
 739                 set_error_handler( [ $this, 'connectionerrorLogger' ] );
 740         }
 741
 742         /**
 743          * @return bool|string
 744          */
 745         protected function restoreErrorHandler() {
 746                 restore_error_handler();
 747                 if ( $this->htmlErrors !== false ) {
 748                         ini_set( 'html_errors', $this->htmlErrors );
 749                 }
 750                 if ( $this->mPHPError ) {
 751                         $error = preg_replace( '!\[<a.*</a>\]!', '', $this->mPHPError );
 752                         $error = preg_replace( '!^.*?:\s?(.*)$!', '$1', $error );
 753
 754                         return $error;
 755                 } else {
 756                         return false;
 757                 }
 758         }
 759
 760         /**
 761          * @param int $errno
 762          * @param string $errstr
 763          */
 764         public function connectionerrorLogger( $errno, $errstr ) {
 765                 $this->mPHPError = $errstr;
 766         }
 767
 768         /**
 769          * Create a log context to pass to PSR logging functions.
 770          *
 771          * @param array $extras Additional data to add to context
 772          * @return array
 773          */
 774         protected function getLogContext( array $extras = [] ) {
 775                 return array_merge(
 776                         [
 777                                 'db_server' => $this->mServer,
 778                                 'db_name' => $this->mDBname,
 779                                 'db_user' => $this->mUser,
 780                         ],
 781                         $extras
 782                 );
 783         }
 784
 785         public function close() {
 786                 if ( $this->mConn ) {
 787                         if ( $this->trxLevel() ) {
 788                                 $this->commit( __METHOD__, self::FLUSHING_INTERNAL );
 789                         }
 790
 791                         $closed = $this->closeConnection();
 792                         $this->mConn = false;
 793                 } elseif ( $this->mTrxIdleCallbacks || $this->mTrxEndCallbacks ) { // sanity
 794                         throw new RuntimeException( "Transaction callbacks still pending." );
 795                 } else {
 796                         $closed = true;
 797                 }
 798                 $this->mOpened = false;
 799
 800                 return $closed;
 801         }
 802
 803         /**
 804          * Make sure isOpen() returns true as a sanity check
 805          *
 806          * @throws DBUnexpectedError
 807          */
 808         protected function assertOpen() {
 809                 if ( !$this->isOpen() ) {
 810                         throw new DBUnexpectedError( $this, "DB connection was already closed." );
 811                 }
 812         }
 813
 814         /**
 815          * Closes underlying database connection
 816          * @since 1.20
 817          * @return bool Whether connection was closed successfully
 818          */
 819         abstract protected function closeConnection();
 820
 821         function reportConnectionError( $error = 'Unknown error' ) {
 822                 $myError = $this->lastError();
 823                 if ( $myError ) {
 824                         $error = $myError;
 825                 }
 826
 827                 # New method
 828                 throw new DBConnectionError( $this, $error );
 829         }
 830
 831         /**
 832          * The DBMS-dependent part of query()
 833          *
 834          * @param string $sql SQL query.
 835          * @return ResultWrapper|bool Result object to feed to fetchObject,
 836          *   fetchRow, ...; or false on failure
 837          */
 838         abstract protected function doQuery( $sql );
 839
 840         /**
 841          * Determine whether a query writes to the DB.
 842          * Should return true if unsure.
 843          *
 844          * @param string $sql
 845          * @return bool
 846          */
 847         protected function isWriteQuery( $sql ) {
 848                 return !preg_match(
 849                         '/^(?:SELECT|BEGIN|ROLLBACK|COMMIT|SET|SHOW|EXPLAIN|\(SELECT)\b/i', $sql );
 850         }
 851
 852         /**
 853          * @param $sql
 854          * @return string|null
 855          */
 856         protected function getQueryVerb( $sql ) {
 857                 return preg_match( '/^\s*([a-z]+)/i', $sql, $m ) ? strtoupper( $m[1] ) : null;
 858         }
 859
 860         /**
 861          * Determine whether a SQL statement is sensitive to isolation level.
 862          * A SQL statement is considered transactable if its result could vary
 863          * depending on the transaction isolation level. Operational commands
 864          * such as 'SET' and 'SHOW' are not considered to be transactable.
 865          *
 866          * @param string $sql
 867          * @return bool
 868          */
 869         protected function isTransactableQuery( $sql ) {
 870                 $verb = $this->getQueryVerb( $sql );
 871                 return !in_array( $verb, [ 'BEGIN', 'COMMIT', 'ROLLBACK', 'SHOW', 'SET' ], true );
 872         }
 873
 874         public function query( $sql, $fname = __METHOD__, $tempIgnore = false ) {
 875                 $priorWritesPending = $this->writesOrCallbacksPending();
 876                 $this->mLastQuery = $sql;
 877
 878                 $isWrite = $this->isWriteQuery( $sql );
 879                 if ( $isWrite ) {
 880                         $reason = $this->getReadOnlyReason();
 881                         if ( $reason !== false ) {
 882                                 throw new DBReadOnlyError( $this, "Database is read-only: $reason" );
 883                         }
 884                         # Set a flag indicating that writes have been done
 885                         $this->mDoneWrites = microtime( true );
 886                 }
 887
 888                 // Add trace comment to the begin of the sql string, right after the operator.
 889                 // Or, for one-word queries (like "BEGIN" or COMMIT") add it to the end (bug 42598)
 890                 $commentedSql = preg_replace( '/\s|$/', " /* $fname {$this->agent} */ ", $sql, 1 );
 891
 892                 # Start implicit transactions that wrap the request if DBO_TRX is enabled
 893                 if ( !$this->mTrxLevel && $this->getFlag( DBO_TRX )
 894                         && $this->isTransactableQuery( $sql )
 895                 ) {
 896                         $this->begin( __METHOD__ . " ($fname)", self::TRANSACTION_INTERNAL );
 897                         $this->mTrxAutomatic = true;
 898                 }
 899
 900                 # Keep track of whether the transaction has write queries pending
 901                 if ( $this->mTrxLevel && !$this->mTrxDoneWrites && $isWrite ) {
 902                         $this->mTrxDoneWrites = true;
 903                         $this->trxProfiler->transactionWritingIn(
 904                                 $this->mServer, $this->mDBname, $this->mTrxShortId );
 905                 }
 906
 907                 if ( $this->debug() ) {
 908                         $this->queryLogger->debug( "{$this->mDBname} {$commentedSql}" );
 909                 }
 910
 911                 # Avoid fatals if close() was called
 912                 $this->assertOpen();
 913
 914                 # Send the query to the server
 915                 $ret = $this->doProfiledQuery( $sql, $commentedSql, $isWrite, $fname );
 916
 917                 # Try reconnecting if the connection was lost
 918                 if ( false === $ret && $this->wasErrorReissuable() ) {
 919                         $recoverable = $this->canRecoverFromDisconnect( $sql, $priorWritesPending );
 920                         # Stash the last error values before anything might clear them
 921                         $lastError = $this->lastError();
 922                         $lastErrno = $this->lastErrno();
 923                         # Update state tracking to reflect transaction loss due to disconnection
 924                         $this->handleTransactionLoss();
 925                         if ( $this->reconnect() ) {
 926                                 $msg = __METHOD__ . ": lost connection to {$this->getServer()}; reconnected";
 927                                 $this->connLogger->warning( $msg );
 928                                 $this->queryLogger->warning(
 929                                         "$msg:\n" . ( new RuntimeException() )->getTraceAsString() );
 930
 931                                 if ( !$recoverable ) {
 932                                         # Callers may catch the exception and continue to use the DB
 933                                         $this->reportQueryError( $lastError, $lastErrno, $sql, $fname );
 934                                 } else {
 935                                         # Should be safe to silently retry the query
 936                                         $ret = $this->doProfiledQuery( $sql, $commentedSql, $isWrite, $fname );
 937                                 }
 938                         } else {
 939                                 $msg = __METHOD__ . ": lost connection to {$this->getServer()} permanently";
 940                                 $this->connLogger->error( $msg );
 941                         }
 942                 }
 943
 944                 if ( false === $ret ) {
 945                         # Deadlocks cause the entire transaction to abort, not just the statement.
 946                         # http://dev.mysql.com/doc/refman/5.7/en/innodb-error-handling.html
 947                         # https://www.postgresql.org/docs/9.1/static/explicit-locking.html
 948                         if ( $this->wasDeadlock() ) {
 949                                 if ( $this->explicitTrxActive() || $priorWritesPending ) {
 950                                         $tempIgnore = false; // not recoverable
 951                                 }
 952                                 # Update state tracking to reflect transaction loss
 953                                 $this->handleTransactionLoss();
 954                         }
 955
 956                         $this->reportQueryError(
 957                                 $this->lastError(), $this->lastErrno(), $sql, $fname, $tempIgnore );
 958                 }
 959
 960                 $res = $this->resultObject( $ret );
 961
 962                 return $res;
 963         }
 964
 965         private function doProfiledQuery( $sql, $commentedSql, $isWrite, $fname ) {
 966                 $isMaster = !is_null( $this->getLBInfo( 'master' ) );
 967                 # generalizeSQL() will probably cut down the query to reasonable
 968                 # logging size most of the time. The substr is really just a sanity check.
 969                 if ( $isMaster ) {
 970                         $queryProf = 'query-m: ' . substr( self::generalizeSQL( $sql ), 0, 255 );
 971                 } else {
 972                         $queryProf = 'query: ' . substr( self::generalizeSQL( $sql ), 0, 255 );
 973                 }
 974
 975                 # Include query transaction state
 976                 $queryProf .= $this->mTrxShortId ? " [TRX#{$this->mTrxShortId}]" : "";
 977
 978                 $startTime = microtime( true );
 979                 $this->profiler->profileIn( $queryProf );
 980                 $ret = $this->doQuery( $commentedSql );
 981                 $this->profiler->profileOut( $queryProf );
 982                 $queryRuntime = max( microtime( true ) - $startTime, 0.0 );
 983
 984                 unset( $queryProfSection ); // profile out (if set)
 985
 986                 if ( $ret !== false ) {
 987                         $this->lastPing = $startTime;
 988                         if ( $isWrite && $this->mTrxLevel ) {
 989                                 $this->updateTrxWriteQueryTime( $sql, $queryRuntime );
 990                                 $this->mTrxWriteCallers[] = $fname;
 991                         }
 992                 }
 993
 994                 if ( $sql === self::PING_QUERY ) {
 995                         $this->mRTTEstimate = $queryRuntime;
 996                 }
 997
 998                 $this->trxProfiler->recordQueryCompletion(
 999                         $queryProf, $startTime, $isWrite, $this->affectedRows()
1000                 );
1001                 MWDebug::query( $sql, $fname, $isMaster, $queryRuntime );
1002
1003                 return $ret;
1004         }
1005
1006         /**
1007          * Update the estimated run-time of a query, not counting large row lock times
1008          *
1009          * LoadBalancer can be set to rollback transactions that will create huge replication
1010          * lag. It bases this estimate off of pendingWriteQueryDuration(). Certain simple
1011          * queries, like inserting a row can take a long time due to row locking. This method
1012          * uses some simple heuristics to discount those cases.
1013          *
1014          * @param string $sql A SQL write query
1015          * @param float $runtime Total runtime, including RTT
1016          */
1017         private function updateTrxWriteQueryTime( $sql, $runtime ) {
1018                 // Whether this is indicative of replica DB runtime (except for RBR or ws_repl)
1019                 $indicativeOfReplicaRuntime = true;
1020                 if ( $runtime > self::SLOW_WRITE_SEC ) {
1021                         $verb = $this->getQueryVerb( $sql );
1022                         // insert(), upsert(), replace() are fast unless bulky in size or blocked on locks
1023                         if ( $verb === 'INSERT' ) {
1024                                 $indicativeOfReplicaRuntime = $this->affectedRows() > self::SMALL_WRITE_ROWS;
1025                         } elseif ( $verb === 'REPLACE' ) {
1026                                 $indicativeOfReplicaRuntime = $this->affectedRows() > self::SMALL_WRITE_ROWS / 2;
1027                         }
1028                 }
1029
1030                 $this->mTrxWriteDuration += $runtime;
1031                 $this->mTrxWriteQueryCount += 1;
1032                 if ( $indicativeOfReplicaRuntime ) {
1033                         $this->mTrxWriteAdjDuration += $runtime;
1034                         $this->mTrxWriteAdjQueryCount += 1;
1035                 }
1036         }
1037
1038         private function canRecoverFromDisconnect( $sql, $priorWritesPending ) {
1039                 # Transaction dropped; this can mean lost writes, or REPEATABLE-READ snapshots.
1040                 # Dropped connections also mean that named locks are automatically released.
1041                 # Only allow error suppression in autocommit mode or when the lost transaction
1042                 # didn't matter anyway (aside from DBO_TRX snapshot loss).
1043                 if ( $this->mNamedLocksHeld ) {
1044                         return false; // possible critical section violation
1045                 } elseif ( $sql === 'COMMIT' ) {
1046                         return !$priorWritesPending; // nothing written anyway? (T127428)
1047                 } elseif ( $sql === 'ROLLBACK' ) {
1048                         return true; // transaction lost...which is also what was requested :)
1049                 } elseif ( $this->explicitTrxActive() ) {
1050                         return false; // don't drop atomocity
1051                 } elseif ( $priorWritesPending ) {
1052                         return false; // prior writes lost from implicit transaction
1053                 }
1054
1055                 return true;
1056         }
1057
1058         private function handleTransactionLoss() {
1059                 $this->mTrxLevel = 0;
1060                 $this->mTrxIdleCallbacks = []; // bug 65263
1061                 $this->mTrxPreCommitCallbacks = []; // bug 65263
1062                 try {
1063                         // Handle callbacks in mTrxEndCallbacks
1064                         $this->runOnTransactionIdleCallbacks( self::TRIGGER_ROLLBACK );
1065                         $this->runTransactionListenerCallbacks( self::TRIGGER_ROLLBACK );
1066                         return null;
1067                 } catch ( Exception $e ) {
1068                         // Already logged; move on...
1069                         return $e;
1070                 }
1071         }
1072
1073         public function reportQueryError( $error, $errno, $sql, $fname, $tempIgnore = false ) {
1074                 if ( $this->ignoreErrors() || $tempIgnore ) {
1075                         $this->queryLogger->debug( "SQL ERROR (ignored): $error\n" );
1076                 } else {
1077                         $sql1line = mb_substr( str_replace( "\n", "\\n", $sql ), 0, 5 * 1024 );
1078                         $this->queryLogger->error(
1079                                 "{fname}\t{db_server}\t{errno}\t{error}\t{sql1line}",
1080                                 $this->getLogContext( [
1081                                         'method' => __METHOD__,
1082                                         'errno' => $errno,
1083                                         'error' => $error,
1084                                         'sql1line' => $sql1line,
1085                                         'fname' => $fname,
1086                                 ] )
1087                         );
1088                         $this->queryLogger->debug( "SQL ERROR: " . $error . "\n" );
1089                         throw new DBQueryError( $this, $error, $errno, $sql, $fname );
1090                 }
1091         }
1092
1093         /**
1094          * Intended to be compatible with the PEAR::DB wrapper functions.
1095          * http://pear.php.net/manual/en/package.database.db.intro-execute.php
1096          *
1097          * ? = scalar value, quoted as necessary
1098          * ! = raw SQL bit (a function for instance)
1099          * & = filename; reads the file and inserts as a blob
1100          *     (we don't use this though...)
1101          *
1102          * @param string $sql
1103          * @param string $func
1104          *
1105          * @return array
1106          */
1107         protected function prepare( $sql, $func = __METHOD__ ) {
1108                 /* MySQL doesn't support prepared statements (yet), so just
1109                  * pack up the query for reference. We'll manually replace
1110                  * the bits later.
1111                  */
1112                 return [ 'query' => $sql, 'func' => $func ];
1113         }
1114
1115         /**
1116          * Free a prepared query, generated by prepare().
1117          * @param string $prepared
1118          */
1119         protected function freePrepared( $prepared ) {
1120                 /* No-op by default */
1121         }
1122
1123         /**
1124          * Execute a prepared query with the various arguments
1125          * @param string $prepared The prepared sql
1126          * @param mixed $args Either an array here, or put scalars as varargs
1127          *
1128          * @return ResultWrapper
1129          */
1130         public function execute( $prepared, $args = null ) {
1131                 if ( !is_array( $args ) ) {
1132                         # Pull the var args
1133                         $args = func_get_args();
1134                         array_shift( $args );
1135                 }
1136
1137                 $sql = $this->fillPrepared( $prepared['query'], $args );
1138
1139                 return $this->query( $sql, $prepared['func'] );
1140         }
1141
1142         /**
1143          * For faking prepared SQL statements on DBs that don't support it directly.
1144          *
1145          * @param string $preparedQuery A 'preparable' SQL statement
1146          * @param array $args Array of Arguments to fill it with
1147          * @return string Executable SQL
1148          */
1149         public function fillPrepared( $preparedQuery, $args ) {
1150                 reset( $args );
1151                 $this->preparedArgs =& $args;
1152
1153                 return preg_replace_callback( '/(\\\\[?!&]|[?!&])/',
1154                         [ &$this, 'fillPreparedArg' ], $preparedQuery );
1155         }
1156
1157         /**
1158          * preg_callback func for fillPrepared()
1159          * The arguments should be in $this->preparedArgs and must not be touched
1160          * while we're doing this.
1161          *
1162          * @param array $matches
1163          * @throws DBUnexpectedError
1164          * @return string
1165          */
1166         protected function fillPreparedArg( $matches ) {
1167                 switch ( $matches[1] ) {
1168                         case '\\?':
1169                                 return '?';
1170                         case '\\!':
1171                                 return '!';
1172                         case '\\&':
1173                                 return '&';
1174                 }
1175
1176                 list( /* $n */, $arg ) = each( $this->preparedArgs );
1177
1178                 switch ( $matches[1] ) {
1179                         case '?':
1180                                 return $this->addQuotes( $arg );
1181                         case '!':
1182                                 return $arg;
1183                         case '&':
1184                                 # return $this->addQuotes( file_get_contents( $arg ) );
1185                                 throw new DBUnexpectedError(
1186                                         $this,
1187                                         '& mode is not implemented. If it\'s really needed, uncomment the line above.'
1188                                 );
1189                         default:
1190                                 throw new DBUnexpectedError(
1191                                         $this,
1192                                         'Received invalid match. This should never happen!'
1193                                 );
1194                 }
1195         }
1196
1197         public function freeResult( $res ) {
1198         }
1199
1200         public function selectField(
1201                 $table, $var, $cond = '', $fname = __METHOD__, $options = []
1202         ) {
1203                 if ( $var === '*' ) { // sanity
1204                         throw new DBUnexpectedError( $this, "Cannot use a * field: got '$var'" );
1205                 }
1206
1207                 if ( !is_array( $options ) ) {
1208                         $options = [ $options ];
1209                 }
1210
1211                 $options['LIMIT'] = 1;
1212
1213                 $res = $this->select( $table, $var, $cond, $fname, $options );
1214                 if ( $res === false || !$this->numRows( $res ) ) {
1215                         return false;
1216                 }
1217
1218                 $row = $this->fetchRow( $res );
1219
1220                 if ( $row !== false ) {
1221                         return reset( $row );
1222                 } else {
1223                         return false;
1224                 }
1225         }
1226
1227         public function selectFieldValues(
1228                 $table, $var, $cond = '', $fname = __METHOD__, $options = [], $join_conds = []
1229         ) {
1230                 if ( $var === '*' ) { // sanity
1231                         throw new DBUnexpectedError( $this, "Cannot use a * field" );
1232                 } elseif ( !is_string( $var ) ) { // sanity
1233                         throw new DBUnexpectedError( $this, "Cannot use an array of fields" );
1234                 }
1235
1236                 if ( !is_array( $options ) ) {
1237                         $options = [ $options ];
1238                 }
1239
1240                 $res = $this->select( $table, $var, $cond, $fname, $options, $join_conds );
1241                 if ( $res === false ) {
1242                         return false;
1243                 }
1244
1245                 $values = [];
1246                 foreach ( $res as $row ) {
1247                         $values[] = $row->$var;
1248                 }
1249
1250                 return $values;
1251         }
1252
1253         /**
1254          * Returns an optional USE INDEX clause to go after the table, and a
1255          * string to go at the end of the query.
1256          *
1257          * @param array $options Associative array of options to be turned into
1258          *   an SQL query, valid keys are listed in the function.
1259          * @return array
1260          * @see DatabaseBase::select()
1261          */
1262         public function makeSelectOptions( $options ) {
1263                 $preLimitTail = $postLimitTail = '';
1264                 $startOpts = '';
1265
1266                 $noKeyOptions = [];
1267
1268                 foreach ( $options as $key => $option ) {
1269                         if ( is_numeric( $key ) ) {
1270                                 $noKeyOptions[$option] = true;
1271                         }
1272                 }
1273
1274                 $preLimitTail .= $this->makeGroupByWithHaving( $options );
1275
1276                 $preLimitTail .= $this->makeOrderBy( $options );
1277
1278                 // if (isset($options['LIMIT'])) {
1279                 //      $tailOpts .= $this->limitResult('', $options['LIMIT'],
1280                 //              isset($options['OFFSET']) ? $options['OFFSET']
1281                 //              : false);
1282                 // }
1283
1284                 if ( isset( $noKeyOptions['FOR UPDATE'] ) ) {
1285                         $postLimitTail .= ' FOR UPDATE';
1286                 }
1287
1288                 if ( isset( $noKeyOptions['LOCK IN SHARE MODE'] ) ) {
1289                         $postLimitTail .= ' LOCK IN SHARE MODE';
1290                 }
1291
1292                 if ( isset( $noKeyOptions['DISTINCT'] ) || isset( $noKeyOptions['DISTINCTROW'] ) ) {
1293                         $startOpts .= 'DISTINCT';
1294                 }
1295
1296                 # Various MySQL extensions
1297                 if ( isset( $noKeyOptions['STRAIGHT_JOIN'] ) ) {
1298                         $startOpts .= ' /*! STRAIGHT_JOIN */';
1299                 }
1300
1301                 if ( isset( $noKeyOptions['HIGH_PRIORITY'] ) ) {
1302                         $startOpts .= ' HIGH_PRIORITY';
1303                 }
1304
1305                 if ( isset( $noKeyOptions['SQL_BIG_RESULT'] ) ) {
1306                         $startOpts .= ' SQL_BIG_RESULT';
1307                 }
1308
1309                 if ( isset( $noKeyOptions['SQL_BUFFER_RESULT'] ) ) {
1310                         $startOpts .= ' SQL_BUFFER_RESULT';
1311                 }
1312
1313                 if ( isset( $noKeyOptions['SQL_SMALL_RESULT'] ) ) {
1314                         $startOpts .= ' SQL_SMALL_RESULT';
1315                 }
1316
1317                 if ( isset( $noKeyOptions['SQL_CALC_FOUND_ROWS'] ) ) {
1318                         $startOpts .= ' SQL_CALC_FOUND_ROWS';
1319                 }
1320
1321                 if ( isset( $noKeyOptions['SQL_CACHE'] ) ) {
1322                         $startOpts .= ' SQL_CACHE';
1323                 }
1324
1325                 if ( isset( $noKeyOptions['SQL_NO_CACHE'] ) ) {
1326                         $startOpts .= ' SQL_NO_CACHE';
1327                 }
1328
1329                 if ( isset( $options['USE INDEX'] ) && is_string( $options['USE INDEX'] ) ) {
1330                         $useIndex = $this->useIndexClause( $options['USE INDEX'] );
1331                 } else {
1332                         $useIndex = '';
1333                 }
1334                 if ( isset( $options['IGNORE INDEX'] ) && is_string( $options['IGNORE INDEX'] ) ) {
1335                         $ignoreIndex = $this->ignoreIndexClause( $options['IGNORE INDEX'] );
1336                 } else {
1337                         $ignoreIndex = '';
1338                 }
1339
1340                 return [ $startOpts, $useIndex, $preLimitTail, $postLimitTail, $ignoreIndex ];
1341         }
1342
1343         /**
1344          * Returns an optional GROUP BY with an optional HAVING
1345          *
1346          * @param array $options Associative array of options
1347          * @return string
1348          * @see DatabaseBase::select()
1349          * @since 1.21
1350          */
1351         public function makeGroupByWithHaving( $options ) {
1352                 $sql = '';
1353                 if ( isset( $options['GROUP BY'] ) ) {
1354                         $gb = is_array( $options['GROUP BY'] )
1355                                 ? implode( ',', $options['GROUP BY'] )
1356                                 : $options['GROUP BY'];
1357                         $sql .= ' GROUP BY ' . $gb;
1358                 }
1359                 if ( isset( $options['HAVING'] ) ) {
1360                         $having = is_array( $options['HAVING'] )
1361                                 ? $this->makeList( $options['HAVING'], LIST_AND )
1362                                 : $options['HAVING'];
1363                         $sql .= ' HAVING ' . $having;
1364                 }
1365
1366                 return $sql;
1367         }
1368
1369         /**
1370          * Returns an optional ORDER BY
1371          *
1372          * @param array $options Associative array of options
1373          * @return string
1374          * @see DatabaseBase::select()
1375          * @since 1.21
1376          */
1377         public function makeOrderBy( $options ) {
1378                 if ( isset( $options['ORDER BY'] ) ) {
1379                         $ob = is_array( $options['ORDER BY'] )
1380                                 ? implode( ',', $options['ORDER BY'] )
1381                                 : $options['ORDER BY'];
1382
1383                         return ' ORDER BY ' . $ob;
1384                 }
1385
1386                 return '';
1387         }
1388
1389         // See IDatabase::select for the docs for this function
1390         public function select( $table, $vars, $conds = '', $fname = __METHOD__,
1391                 $options = [], $join_conds = [] ) {
1392                 $sql = $this->selectSQLText( $table, $vars, $conds, $fname, $options, $join_conds );
1393
1394                 return $this->query( $sql, $fname );
1395         }
1396
1397         public function selectSQLText( $table, $vars, $conds = '', $fname = __METHOD__,
1398                 $options = [], $join_conds = []
1399         ) {
1400                 if ( is_array( $vars ) ) {
1401                         $vars = implode( ',', $this->fieldNamesWithAlias( $vars ) );
1402                 }
1403
1404                 $options = (array)$options;
1405                 $useIndexes = ( isset( $options['USE INDEX'] ) && is_array( $options['USE INDEX'] ) )
1406                         ? $options['USE INDEX']
1407                         : [];
1408                 $ignoreIndexes = ( isset( $options['IGNORE INDEX'] ) && is_array( $options['IGNORE INDEX'] ) )
1409                         ? $options['IGNORE INDEX']
1410                         : [];
1411
1412                 if ( is_array( $table ) ) {
1413                         $from = ' FROM ' .
1414                                 $this->tableNamesWithIndexClauseOrJOIN( $table, $useIndexes, $ignoreIndexes, $join_conds );
1415                 } elseif ( $table != '' ) {
1416                         if ( $table[0] == ' ' ) {
1417                                 $from = ' FROM ' . $table;
1418                         } else {
1419                                 $from = ' FROM ' .
1420                                         $this->tableNamesWithIndexClauseOrJOIN( [ $table ], $useIndexes, $ignoreIndexes, [] );
1421                         }
1422                 } else {
1423                         $from = '';
1424                 }
1425
1426                 list( $startOpts, $useIndex, $preLimitTail, $postLimitTail, $ignoreIndex ) =
1427                         $this->makeSelectOptions( $options );
1428
1429                 if ( !empty( $conds ) ) {
1430                         if ( is_array( $conds ) ) {
1431                                 $conds = $this->makeList( $conds, LIST_AND );
1432                         }
1433                         $sql = "SELECT $startOpts $vars $from $useIndex $ignoreIndex WHERE $conds $preLimitTail";
1434                 } else {
1435                         $sql = "SELECT $startOpts $vars $from $useIndex $ignoreIndex $preLimitTail";
1436                 }
1437
1438                 if ( isset( $options['LIMIT'] ) ) {
1439                         $sql = $this->limitResult( $sql, $options['LIMIT'],
1440                                 isset( $options['OFFSET'] ) ? $options['OFFSET'] : false );
1441                 }
1442                 $sql = "$sql $postLimitTail";
1443
1444                 if ( isset( $options['EXPLAIN'] ) ) {
1445                         $sql = 'EXPLAIN ' . $sql;
1446                 }
1447
1448                 return $sql;
1449         }
1450
1451         public function selectRow( $table, $vars, $conds, $fname = __METHOD__,
1452                 $options = [], $join_conds = []
1453         ) {
1454                 $options = (array)$options;
1455                 $options['LIMIT'] = 1;
1456                 $res = $this->select( $table, $vars, $conds, $fname, $options, $join_conds );
1457
1458                 if ( $res === false ) {
1459                         return false;
1460                 }
1461
1462                 if ( !$this->numRows( $res ) ) {
1463                         return false;
1464                 }
1465
1466                 $obj = $this->fetchObject( $res );
1467
1468                 return $obj;
1469         }
1470
1471         public function estimateRowCount(
1472                 $table, $vars = '*', $conds = '', $fname = __METHOD__, $options = []
1473         ) {
1474                 $rows = 0;
1475                 $res = $this->select( $table, [ 'rowcount' => 'COUNT(*)' ], $conds, $fname, $options );
1476
1477                 if ( $res ) {
1478                         $row = $this->fetchRow( $res );
1479                         $rows = ( isset( $row['rowcount'] ) ) ? (int)$row['rowcount'] : 0;
1480                 }
1481
1482                 return $rows;
1483         }
1484
1485         public function selectRowCount(
1486                 $tables, $vars = '*', $conds = '', $fname = __METHOD__, $options = [], $join_conds = []
1487         ) {
1488                 $rows = 0;
1489                 $sql = $this->selectSQLText( $tables, '1', $conds, $fname, $options, $join_conds );
1490                 $res = $this->query( "SELECT COUNT(*) AS rowcount FROM ($sql) tmp_count", $fname );
1491
1492                 if ( $res ) {
1493                         $row = $this->fetchRow( $res );
1494                         $rows = ( isset( $row['rowcount'] ) ) ? (int)$row['rowcount'] : 0;
1495                 }
1496
1497                 return $rows;
1498         }
1499
1500         /**
1501          * Removes most variables from an SQL query and replaces them with X or N for numbers.
1502          * It's only slightly flawed. Don't use for anything important.
1503          *
1504          * @param string $sql A SQL Query
1505          *
1506          * @return string
1507          */
1508         protected static function generalizeSQL( $sql ) {
1509                 # This does the same as the regexp below would do, but in such a way
1510                 # as to avoid crashing php on some large strings.
1511                 # $sql = preg_replace( "/'([^\\\\']|\\\\.)*'|\"([^\\\\\"]|\\\\.)*\"/", "'X'", $sql );
1512
1513                 $sql = str_replace( "\\\\", '', $sql );
1514                 $sql = str_replace( "\\'", '', $sql );
1515                 $sql = str_replace( "\\\"", '', $sql );
1516                 $sql = preg_replace( "/'.*'/s", "'X'", $sql );
1517                 $sql = preg_replace( '/".*"/s', "'X'", $sql );
1518
1519                 # All newlines, tabs, etc replaced by single space
1520                 $sql = preg_replace( '/\s+/', ' ', $sql );
1521
1522                 # All numbers => N,
1523                 # except the ones surrounded by characters, e.g. l10n
1524                 $sql = preg_replace( '/-?\d+(,-?\d+)+/s', 'N,...,N', $sql );
1525                 $sql = preg_replace( '/(?<![a-zA-Z])-?\d+(?![a-zA-Z])/s', 'N', $sql );
1526
1527                 return $sql;
1528         }
1529
1530         public function fieldExists( $table, $field, $fname = __METHOD__ ) {
1531                 $info = $this->fieldInfo( $table, $field );
1532
1533                 return (bool)$info;
1534         }
1535
1536         public function indexExists( $table, $index, $fname = __METHOD__ ) {
1537                 if ( !$this->tableExists( $table ) ) {
1538                         return null;
1539                 }
1540
1541                 $info = $this->indexInfo( $table, $index, $fname );
1542                 if ( is_null( $info ) ) {
1543                         return null;
1544                 } else {
1545                         return $info !== false;
1546                 }
1547         }
1548
1549         public function tableExists( $table, $fname = __METHOD__ ) {
1550                 $table = $this->tableName( $table );
1551                 $old = $this->ignoreErrors( true );
1552                 $res = $this->query( "SELECT 1 FROM $table LIMIT 1", $fname );
1553                 $this->ignoreErrors( $old );
1554
1555                 return (bool)$res;
1556         }
1557
1558         public function indexUnique( $table, $index ) {
1559                 $indexInfo = $this->indexInfo( $table, $index );
1560
1561                 if ( !$indexInfo ) {
1562                         return null;
1563                 }
1564
1565                 return !$indexInfo[0]->Non_unique;
1566         }
1567
1568         /**
1569          * Helper for DatabaseBase::insert().
1570          *
1571          * @param array $options
1572          * @return string
1573          */
1574         protected function makeInsertOptions( $options ) {
1575                 return implode( ' ', $options );
1576         }
1577
1578         public function insert( $table, $a, $fname = __METHOD__, $options = [] ) {
1579                 # No rows to insert, easy just return now
1580                 if ( !count( $a ) ) {
1581                         return true;
1582                 }
1583
1584                 $table = $this->tableName( $table );
1585
1586                 if ( !is_array( $options ) ) {
1587                         $options = [ $options ];
1588                 }
1589
1590                 $fh = null;
1591                 if ( isset( $options['fileHandle'] ) ) {
1592                         $fh = $options['fileHandle'];
1593                 }
1594                 $options = $this->makeInsertOptions( $options );
1595
1596                 if ( isset( $a[0] ) && is_array( $a[0] ) ) {
1597                         $multi = true;
1598                         $keys = array_keys( $a[0] );
1599                 } else {
1600                         $multi = false;
1601                         $keys = array_keys( $a );
1602                 }
1603
1604                 $sql = 'INSERT ' . $options .
1605                         " INTO $table (" . implode( ',', $keys ) . ') VALUES ';
1606
1607                 if ( $multi ) {
1608                         $first = true;
1609                         foreach ( $a as $row ) {
1610                                 if ( $first ) {
1611                                         $first = false;
1612                                 } else {
1613                                         $sql .= ',';
1614                                 }
1615                                 $sql .= '(' . $this->makeList( $row ) . ')';
1616                         }
1617                 } else {
1618                         $sql .= '(' . $this->makeList( $a ) . ')';
1619                 }
1620
1621                 if ( $fh !== null && false === fwrite( $fh, $sql ) ) {
1622                         return false;
1623                 } elseif ( $fh !== null ) {
1624                         return true;
1625                 }
1626
1627                 return (bool)$this->query( $sql, $fname );
1628         }
1629
1630         /**
1631          * Make UPDATE options array for DatabaseBase::makeUpdateOptions
1632          *
1633          * @param array $options
1634          * @return array
1635          */
1636         protected function makeUpdateOptionsArray( $options ) {
1637                 if ( !is_array( $options ) ) {
1638                         $options = [ $options ];
1639                 }
1640
1641                 $opts = [];
1642
1643                 if ( in_array( 'LOW_PRIORITY', $options ) ) {
1644                         $opts[] = $this->lowPriorityOption();
1645                 }
1646
1647                 if ( in_array( 'IGNORE', $options ) ) {
1648                         $opts[] = 'IGNORE';
1649                 }
1650
1651                 return $opts;
1652         }
1653
1654         /**
1655          * Make UPDATE options for the DatabaseBase::update function
1656          *
1657          * @param array $options The options passed to DatabaseBase::update
1658          * @return string
1659          */
1660         protected function makeUpdateOptions( $options ) {
1661                 $opts = $this->makeUpdateOptionsArray( $options );
1662
1663                 return implode( ' ', $opts );
1664         }
1665
1666         function update( $table, $values, $conds, $fname = __METHOD__, $options = [] ) {
1667                 $table = $this->tableName( $table );
1668                 $opts = $this->makeUpdateOptions( $options );
1669                 $sql = "UPDATE $opts $table SET " . $this->makeList( $values, LIST_SET );
1670
1671                 if ( $conds !== [] && $conds !== '*' ) {
1672                         $sql .= " WHERE " . $this->makeList( $conds, LIST_AND );
1673                 }
1674
1675                 return $this->query( $sql, $fname );
1676         }
1677
1678         public function makeList( $a, $mode = LIST_COMMA ) {
1679                 if ( !is_array( $a ) ) {
1680                         throw new DBUnexpectedError( $this, __METHOD__ . ' called with incorrect parameters' );
1681                 }
1682
1683                 $first = true;
1684                 $list = '';
1685
1686                 foreach ( $a as $field => $value ) {
1687                         if ( !$first ) {
1688                                 if ( $mode == LIST_AND ) {
1689                                         $list .= ' AND ';
1690                                 } elseif ( $mode == LIST_OR ) {
1691                                         $list .= ' OR ';
1692                                 } else {
1693                                         $list .= ',';
1694                                 }
1695                         } else {
1696                                 $first = false;
1697                         }
1698
1699                         if ( ( $mode == LIST_AND || $mode == LIST_OR ) && is_numeric( $field ) ) {
1700                                 $list .= "($value)";
1701                         } elseif ( ( $mode == LIST_SET ) && is_numeric( $field ) ) {
1702                                 $list .= "$value";
1703                         } elseif ( ( $mode == LIST_AND || $mode == LIST_OR ) && is_array( $value ) ) {
1704                                 // Remove null from array to be handled separately if found
1705                                 $includeNull = false;
1706                                 foreach ( array_keys( $value, null, true ) as $nullKey ) {
1707                                         $includeNull = true;
1708                                         unset( $value[$nullKey] );
1709                                 }
1710                                 if ( count( $value ) == 0 && !$includeNull ) {
1711                                         throw new InvalidArgumentException( __METHOD__ . ": empty input for field $field" );
1712                                 } elseif ( count( $value ) == 0 ) {
1713                                         // only check if $field is null
1714                                         $list .= "$field IS NULL";
1715                                 } else {
1716                                         // IN clause contains at least one valid element
1717                                         if ( $includeNull ) {
1718                                                 // Group subconditions to ensure correct precedence
1719                                                 $list .= '(';
1720                                         }
1721                                         if ( count( $value ) == 1 ) {
1722                                                 // Special-case single values, as IN isn't terribly efficient
1723                                                 // Don't necessarily assume the single key is 0; we don't
1724                                                 // enforce linear numeric ordering on other arrays here.
1725                                                 $value = array_values( $value )[0];
1726                                                 $list .= $field . " = " . $this->addQuotes( $value );
1727                                         } else {
1728                                                 $list .= $field . " IN (" . $this->makeList( $value ) . ") ";
1729                                         }
1730                                         // if null present in array, append IS NULL
1731                                         if ( $includeNull ) {
1732                                                 $list .= " OR $field IS NULL)";
1733                                         }
1734                                 }
1735                         } elseif ( $value === null ) {
1736                                 if ( $mode == LIST_AND || $mode == LIST_OR ) {
1737                                         $list .= "$field IS ";
1738                                 } elseif ( $mode == LIST_SET ) {
1739                                         $list .= "$field = ";
1740                                 }
1741                                 $list .= 'NULL';
1742                         } else {
1743                                 if ( $mode == LIST_AND || $mode == LIST_OR || $mode == LIST_SET ) {
1744                                         $list .= "$field = ";
1745                                 }
1746                                 $list .= $mode == LIST_NAMES ? $value : $this->addQuotes( $value );
1747                         }
1748                 }
1749
1750                 return $list;
1751         }
1752
1753         public function makeWhereFrom2d( $data, $baseKey, $subKey ) {
1754                 $conds = [];
1755
1756                 foreach ( $data as $base => $sub ) {
1757                         if ( count( $sub ) ) {
1758                                 $conds[] = $this->makeList(
1759                                         [ $baseKey => $base, $subKey => array_keys( $sub ) ],
1760                                         LIST_AND );
1761                         }
1762                 }
1763
1764                 if ( $conds ) {
1765                         return $this->makeList( $conds, LIST_OR );
1766                 } else {
1767                         // Nothing to search for...
1768                         return false;
1769                 }
1770         }
1771
1772         /**
1773          * Return aggregated value alias
1774          *
1775          * @param array $valuedata
1776          * @param string $valuename
1777          *
1778          * @return string
1779          */
1780         public function aggregateValue( $valuedata, $valuename = 'value' ) {
1781                 return $valuename;
1782         }
1783
1784         public function bitNot( $field ) {
1785                 return "(~$field)";
1786         }
1787
1788         public function bitAnd( $fieldLeft, $fieldRight ) {
1789                 return "($fieldLeft & $fieldRight)";
1790         }
1791
1792         public function bitOr( $fieldLeft, $fieldRight ) {
1793                 return "($fieldLeft | $fieldRight)";
1794         }
1795
1796         public function buildConcat( $stringList ) {
1797                 return 'CONCAT(' . implode( ',', $stringList ) . ')';
1798         }
1799
1800         public function buildGroupConcatField(
1801                 $delim, $table, $field, $conds = '', $join_conds = []
1802         ) {
1803                 $fld = "GROUP_CONCAT($field SEPARATOR " . $this->addQuotes( $delim ) . ')';
1804
1805                 return '(' . $this->selectSQLText( $table, $fld, $conds, null, [], $join_conds ) . ')';
1806         }
1807
1808         /**
1809          * @param string $field Field or column to cast
1810          * @return string
1811          * @since 1.28
1812          */
1813         public function buildStringCast( $field ) {
1814                 return $field;
1815         }
1816
1817         public function selectDB( $db ) {
1818                 # Stub. Shouldn't cause serious problems if it's not overridden, but
1819                 # if your database engine supports a concept similar to MySQL's
1820                 # databases you may as well.
1821                 $this->mDBname = $db;
1822
1823                 return true;
1824         }
1825
1826         public function getDBname() {
1827                 return $this->mDBname;
1828         }
1829
1830         public function getServer() {
1831                 return $this->mServer;
1832         }
1833
1834         /**
1835          * Format a table name ready for use in constructing an SQL query
1836          *
1837          * This does two important things: it quotes the table names to clean them up,
1838          * and it adds a table prefix if only given a table name with no quotes.
1839          *
1840          * All functions of this object which require a table name call this function
1841          * themselves. Pass the canonical name to such functions. This is only needed
1842          * when calling query() directly.
1843          *
1844          * @note This function does not sanitize user input. It is not safe to use
1845          *   this function to escape user input.
1846          * @param string $name Database table name
1847          * @param string $format One of:
1848          *   quoted - Automatically pass the table name through addIdentifierQuotes()
1849          *            so that it can be used in a query.
1850          *   raw - Do not add identifier quotes to the table name
1851          * @return string Full database name
1852          */
1853         public function tableName( $name, $format = 'quoted' ) {
1854                 # Skip the entire process when we have a string quoted on both ends.
1855                 # Note that we check the end so that we will still quote any use of
1856                 # use of `database`.table. But won't break things if someone wants
1857                 # to query a database table with a dot in the name.
1858                 if ( $this->isQuotedIdentifier( $name ) ) {
1859                         return $name;
1860                 }
1861
1862                 # Lets test for any bits of text that should never show up in a table
1863                 # name. Basically anything like JOIN or ON which are actually part of
1864                 # SQL queries, but may end up inside of the table value to combine
1865                 # sql. Such as how the API is doing.
1866                 # Note that we use a whitespace test rather than a \b test to avoid
1867                 # any remote case where a word like on may be inside of a table name
1868                 # surrounded by symbols which may be considered word breaks.
1869                 if ( preg_match( '/(^|\s)(DISTINCT|JOIN|ON|AS)(\s|$)/i', $name ) !== 0 ) {
1870                         return $name;
1871                 }
1872
1873                 # Split database and table into proper variables.
1874                 # We reverse the explode so that database.table and table both output
1875                 # the correct table.
1876                 $dbDetails = explode( '.', $name, 3 );
1877                 if ( count( $dbDetails ) == 3 ) {
1878                         list( $database, $schema, $table ) = $dbDetails;
1879                         # We don't want any prefix added in this case
1880                         $prefix = '';
1881                 } elseif ( count( $dbDetails ) == 2 ) {
1882                         list( $database, $table ) = $dbDetails;
1883                         # We don't want any prefix added in this case
1884                         # In dbs that support it, $database may actually be the schema
1885                         # but that doesn't affect any of the functionality here
1886                         $prefix = '';
1887                         $schema = null;
1888                 } else {
1889                         list( $table ) = $dbDetails;
1890                         if ( isset( $this->tableAliases[$table] ) ) {
1891                                 $database = $this->tableAliases[$table]['dbname'];
1892                                 $schema = is_string( $this->tableAliases[$table]['schema'] )
1893                                         ? $this->tableAliases[$table]['schema']
1894                                         : $this->mSchema;
1895                                 $prefix = is_string( $this->tableAliases[$table]['prefix'] )
1896                                         ? $this->tableAliases[$table]['prefix']
1897                                         : $this->mTablePrefix;
1898                         } else {
1899                                 $database = null;
1900                                 $schema = $this->mSchema; # Default schema
1901                                 $prefix = $this->mTablePrefix; # Default prefix
1902                         }
1903                 }
1904
1905                 # Quote $table and apply the prefix if not quoted.
1906                 # $tableName might be empty if this is called from Database::replaceVars()
1907                 $tableName = "{$prefix}{$table}";
1908                 if ( $format == 'quoted'
1909                         && !$this->isQuotedIdentifier( $tableName ) && $tableName !== ''
1910                 ) {
1911                         $tableName = $this->addIdentifierQuotes( $tableName );
1912                 }
1913
1914                 # Quote $schema and merge it with the table name if needed
1915                 if ( strlen( $schema ) ) {
1916                         if ( $format == 'quoted' && !$this->isQuotedIdentifier( $schema ) ) {
1917                                 $schema = $this->addIdentifierQuotes( $schema );
1918                         }
1919                         $tableName = $schema . '.' . $tableName;
1920                 }
1921
1922                 # Quote $database and merge it with the table name if needed
1923                 if ( $database !== null ) {
1924                         if ( $format == 'quoted' && !$this->isQuotedIdentifier( $database ) ) {
1925                                 $database = $this->addIdentifierQuotes( $database );
1926                         }
1927                         $tableName = $database . '.' . $tableName;
1928                 }
1929
1930                 return $tableName;
1931         }
1932
1933         /**
1934          * Fetch a number of table names into an array
1935          * This is handy when you need to construct SQL for joins
1936          *
1937          * Example:
1938          * extract( $dbr->tableNames( 'user', 'watchlist' ) );
1939          * $sql = "SELECT wl_namespace,wl_title FROM $watchlist,$user
1940          *         WHERE wl_user=user_id AND wl_user=$nameWithQuotes";
1941          *
1942          * @return array
1943          */
1944         public function tableNames() {
1945                 $inArray = func_get_args();
1946                 $retVal = [];
1947
1948                 foreach ( $inArray as $name ) {
1949                         $retVal[$name] = $this->tableName( $name );
1950                 }
1951
1952                 return $retVal;
1953         }
1954
1955         /**
1956          * Fetch a number of table names into an zero-indexed numerical array
1957          * This is handy when you need to construct SQL for joins
1958          *
1959          * Example:
1960          * list( $user, $watchlist ) = $dbr->tableNamesN( 'user', 'watchlist' );
1961          * $sql = "SELECT wl_namespace,wl_title FROM $watchlist,$user
1962          *         WHERE wl_user=user_id AND wl_user=$nameWithQuotes";
1963          *
1964          * @return array
1965          */
1966         public function tableNamesN() {
1967                 $inArray = func_get_args();
1968                 $retVal = [];
1969
1970                 foreach ( $inArray as $name ) {
1971                         $retVal[] = $this->tableName( $name );
1972                 }
1973
1974                 return $retVal;
1975         }
1976
1977         /**
1978          * Get an aliased table name
1979          * e.g. tableName AS newTableName
1980          *
1981          * @param string $name Table name, see tableName()
1982          * @param string|bool $alias Alias (optional)
1983          * @return string SQL name for aliased table. Will not alias a table to its own name
1984          */
1985         public function tableNameWithAlias( $name, $alias = false ) {
1986                 if ( !$alias || $alias == $name ) {
1987                         return $this->tableName( $name );
1988                 } else {
1989                         return $this->tableName( $name ) . ' ' . $this->addIdentifierQuotes( $alias );
1990                 }
1991         }
1992
1993         /**
1994          * Gets an array of aliased table names
1995          *
1996          * @param array $tables [ [alias] => table ]
1997          * @return string[] See tableNameWithAlias()
1998          */
1999         public function tableNamesWithAlias( $tables ) {
2000                 $retval = [];
2001                 foreach ( $tables as $alias => $table ) {
2002                         if ( is_numeric( $alias ) ) {
2003                                 $alias = $table;
2004                         }
2005                         $retval[] = $this->tableNameWithAlias( $table, $alias );
2006                 }
2007
2008                 return $retval;
2009         }
2010
2011         /**
2012          * Get an aliased field name
2013          * e.g. fieldName AS newFieldName
2014          *
2015          * @param string $name Field name
2016          * @param string|bool $alias Alias (optional)
2017          * @return string SQL name for aliased field. Will not alias a field to its own name
2018          */
2019         public function fieldNameWithAlias( $name, $alias = false ) {
2020                 if ( !$alias || (string)$alias === (string)$name ) {
2021                         return $name;
2022                 } else {
2023                         return $name . ' AS ' . $this->addIdentifierQuotes( $alias ); // PostgreSQL needs AS
2024                 }
2025         }
2026
2027         /**
2028          * Gets an array of aliased field names
2029          *
2030          * @param array $fields [ [alias] => field ]
2031          * @return string[] See fieldNameWithAlias()
2032          */
2033         public function fieldNamesWithAlias( $fields ) {
2034                 $retval = [];
2035                 foreach ( $fields as $alias => $field ) {
2036                         if ( is_numeric( $alias ) ) {
2037                                 $alias = $field;
2038                         }
2039                         $retval[] = $this->fieldNameWithAlias( $field, $alias );
2040                 }
2041
2042                 return $retval;
2043         }
2044
2045         /**
2046          * Get the aliased table name clause for a FROM clause
2047          * which might have a JOIN and/or USE INDEX or IGNORE INDEX clause
2048          *
2049          * @param array $tables ( [alias] => table )
2050          * @param array $use_index Same as for select()
2051          * @param array $ignore_index Same as for select()
2052          * @param array $join_conds Same as for select()
2053          * @return string
2054          */
2055         protected function tableNamesWithIndexClauseOrJOIN(
2056                 $tables, $use_index = [], $ignore_index = [], $join_conds = []
2057         ) {
2058                 $ret = [];
2059                 $retJOIN = [];
2060                 $use_index = (array)$use_index;
2061                 $ignore_index = (array)$ignore_index;
2062                 $join_conds = (array)$join_conds;
2063
2064                 foreach ( $tables as $alias => $table ) {
2065                         if ( !is_string( $alias ) ) {
2066                                 // No alias? Set it equal to the table name
2067                                 $alias = $table;
2068                         }
2069                         // Is there a JOIN clause for this table?
2070                         if ( isset( $join_conds[$alias] ) ) {
2071                                 list( $joinType, $conds ) = $join_conds[$alias];
2072                                 $tableClause = $joinType;
2073                                 $tableClause .= ' ' . $this->tableNameWithAlias( $table, $alias );
2074                                 if ( isset( $use_index[$alias] ) ) { // has USE INDEX?
2075                                         $use = $this->useIndexClause( implode( ',', (array)$use_index[$alias] ) );
2076                                         if ( $use != '' ) {
2077                                                 $tableClause .= ' ' . $use;
2078                                         }
2079                                 }
2080                                 if ( isset( $ignore_index[$alias] ) ) { // has IGNORE INDEX?
2081                                         $ignore = $this->ignoreIndexClause( implode( ',', (array)$ignore_index[$alias] ) );
2082                                         if ( $ignore != '' ) {
2083                                                 $tableClause .= ' ' . $ignore;
2084                                         }
2085                                 }
2086                                 $on = $this->makeList( (array)$conds, LIST_AND );
2087                                 if ( $on != '' ) {
2088                                         $tableClause .= ' ON (' . $on . ')';
2089                                 }
2090
2091                                 $retJOIN[] = $tableClause;
2092                         } elseif ( isset( $use_index[$alias] ) ) {
2093                                 // Is there an INDEX clause for this table?
2094                                 $tableClause = $this->tableNameWithAlias( $table, $alias );
2095                                 $tableClause .= ' ' . $this->useIndexClause(
2096                                         implode( ',', (array)$use_index[$alias] )
2097                                 );
2098
2099                                 $ret[] = $tableClause;
2100                         } elseif ( isset( $ignore_index[$alias] ) ) {
2101                                 // Is there an INDEX clause for this table?
2102                                 $tableClause = $this->tableNameWithAlias( $table, $alias );
2103                                 $tableClause .= ' ' . $this->ignoreIndexClause(
2104                                         implode( ',', (array)$ignore_index[$alias] )
2105                                 );
2106
2107                                 $ret[] = $tableClause;
2108                         } else {
2109                                 $tableClause = $this->tableNameWithAlias( $table, $alias );
2110
2111                                 $ret[] = $tableClause;
2112                         }
2113                 }
2114
2115                 // We can't separate explicit JOIN clauses with ',', use ' ' for those
2116                 $implicitJoins = !empty( $ret ) ? implode( ',', $ret ) : "";
2117                 $explicitJoins = !empty( $retJOIN ) ? implode( ' ', $retJOIN ) : "";
2118
2119                 // Compile our final table clause
2120                 return implode( ' ', [ $implicitJoins, $explicitJoins ] );
2121         }
2122
2123         /**
2124          * Get the name of an index in a given table.
2125          *
2126          * @param string $index
2127          * @return string
2128          */
2129         protected function indexName( $index ) {
2130                 // Backwards-compatibility hack
2131                 $renamed = [
2132                         'ar_usertext_timestamp' => 'usertext_timestamp',
2133                         'un_user_id' => 'user_id',
2134                         'un_user_ip' => 'user_ip',
2135                 ];
2136
2137                 if ( isset( $renamed[$index] ) ) {
2138                         return $renamed[$index];
2139                 } else {
2140                         return $index;
2141                 }
2142         }
2143
2144         public function addQuotes( $s ) {
2145                 if ( $s instanceof Blob ) {
2146                         $s = $s->fetch();
2147                 }
2148                 if ( $s === null ) {
2149                         return 'NULL';
2150                 } else {
2151                         # This will also quote numeric values. This should be harmless,
2152                         # and protects against weird problems that occur when they really
2153                         # _are_ strings such as article titles and string->number->string
2154                         # conversion is not 1:1.
2155                         return "'" . $this->strencode( $s ) . "'";
2156                 }
2157         }
2158
2159         /**
2160          * Quotes an identifier using `backticks` or "double quotes" depending on the database type.
2161          * MySQL uses `backticks` while basically everything else uses double quotes.
2162          * Since MySQL is the odd one out here the double quotes are our generic
2163          * and we implement backticks in DatabaseMysql.
2164          *
2165          * @param string $s
2166          * @return string
2167          */
2168         public function addIdentifierQuotes( $s ) {
2169                 return '"' . str_replace( '"', '""', $s ) . '"';
2170         }
2171
2172         /**
2173          * Returns if the given identifier looks quoted or not according to
2174          * the database convention for quoting identifiers .
2175          *
2176          * @note Do not use this to determine if untrusted input is safe.
2177          *   A malicious user can trick this function.
2178          * @param string $name
2179          * @return bool
2180          */
2181         public function isQuotedIdentifier( $name ) {
2182                 return $name[0] == '"' && substr( $name, -1, 1 ) == '"';
2183         }
2184
2185         /**
2186          * @param string $s
2187          * @return string
2188          */
2189         protected function escapeLikeInternal( $s ) {
2190                 return addcslashes( $s, '\%_' );
2191         }
2192
2193         public function buildLike() {
2194                 $params = func_get_args();
2195
2196                 if ( count( $params ) > 0 && is_array( $params[0] ) ) {
2197                         $params = $params[0];
2198                 }
2199
2200                 $s = '';
2201
2202                 foreach ( $params as $value ) {
2203                         if ( $value instanceof LikeMatch ) {
2204                                 $s .= $value->toString();
2205                         } else {
2206                                 $s .= $this->escapeLikeInternal( $value );
2207                         }
2208                 }
2209
2210                 return " LIKE {$this->addQuotes( $s )} ";
2211         }
2212
2213         public function anyChar() {
2214                 return new LikeMatch( '_' );
2215         }
2216
2217         public function anyString() {
2218                 return new LikeMatch( '%' );
2219         }
2220
2221         public function nextSequenceValue( $seqName ) {
2222                 return null;
2223         }
2224
2225         /**
2226          * USE INDEX clause. Unlikely to be useful for anything but MySQL. This
2227          * is only needed because a) MySQL must be as efficient as possible due to
2228          * its use on Wikipedia, and b) MySQL 4.0 is kind of dumb sometimes about
2229          * which index to pick. Anyway, other databases might have different
2230          * indexes on a given table. So don't bother overriding this unless you're
2231          * MySQL.
2232          * @param string $index
2233          * @return string
2234          */
2235         public function useIndexClause( $index ) {
2236                 return '';
2237         }
2238
2239         /**
2240          * IGNORE INDEX clause. Unlikely to be useful for anything but MySQL. This
2241          * is only needed because a) MySQL must be as efficient as possible due to
2242          * its use on Wikipedia, and b) MySQL 4.0 is kind of dumb sometimes about
2243          * which index to pick. Anyway, other databases might have different
2244          * indexes on a given table. So don't bother overriding this unless you're
2245          * MySQL.
2246          * @param string $index
2247          * @return string
2248          */
2249         public function ignoreIndexClause( $index ) {
2250                 return '';
2251         }
2252
2253         public function replace( $table, $uniqueIndexes, $rows, $fname = __METHOD__ ) {
2254                 $quotedTable = $this->tableName( $table );
2255
2256                 if ( count( $rows ) == 0 ) {
2257                         return;
2258                 }
2259
2260                 # Single row case
2261                 if ( !is_array( reset( $rows ) ) ) {
2262                         $rows = [ $rows ];
2263                 }
2264
2265                 // @FXIME: this is not atomic, but a trx would break affectedRows()
2266                 foreach ( $rows as $row ) {
2267                         # Delete rows which collide
2268                         if ( $uniqueIndexes ) {
2269                                 $sql = "DELETE FROM $quotedTable WHERE ";
2270                                 $first = true;
2271                                 foreach ( $uniqueIndexes as $index ) {
2272                                         if ( $first ) {
2273                                                 $first = false;
2274                                                 $sql .= '( ';
2275                                         } else {
2276                                                 $sql .= ' ) OR ( ';
2277                                         }
2278                                         if ( is_array( $index ) ) {
2279                                                 $first2 = true;
2280                                                 foreach ( $index as $col ) {
2281                                                         if ( $first2 ) {
2282                                                                 $first2 = false;
2283                                                         } else {
2284                                                                 $sql .= ' AND ';
2285                                                         }
2286                                                         $sql .= $col . '=' . $this->addQuotes( $row[$col] );
2287                                                 }
2288                                         } else {
2289                                                 $sql .= $index . '=' . $this->addQuotes( $row[$index] );
2290                                         }
2291                                 }
2292                                 $sql .= ' )';
2293                                 $this->query( $sql, $fname );
2294                         }
2295
2296                         # Now insert the row
2297                         $this->insert( $table, $row, $fname );
2298                 }
2299         }
2300
2301         /**
2302          * REPLACE query wrapper for MySQL and SQLite, which have a native REPLACE
2303          * statement.
2304          *
2305          * @param string $table Table name
2306          * @param array|string $rows Row(s) to insert
2307          * @param string $fname Caller function name
2308          *
2309          * @return ResultWrapper
2310          */
2311         protected function nativeReplace( $table, $rows, $fname ) {
2312                 $table = $this->tableName( $table );
2313
2314                 # Single row case
2315                 if ( !is_array( reset( $rows ) ) ) {
2316                         $rows = [ $rows ];
2317                 }
2318
2319                 $sql = "REPLACE INTO $table (" . implode( ',', array_keys( $rows[0] ) ) . ') VALUES ';
2320                 $first = true;
2321
2322                 foreach ( $rows as $row ) {
2323                         if ( $first ) {
2324                                 $first = false;
2325                         } else {
2326                                 $sql .= ',';
2327                         }
2328
2329                         $sql .= '(' . $this->makeList( $row ) . ')';
2330                 }
2331
2332                 return $this->query( $sql, $fname );
2333         }
2334
2335         public function upsert( $table, array $rows, array $uniqueIndexes, array $set,
2336                 $fname = __METHOD__
2337         ) {
2338                 if ( !count( $rows ) ) {
2339                         return true; // nothing to do
2340                 }
2341
2342                 if ( !is_array( reset( $rows ) ) ) {
2343                         $rows = [ $rows ];
2344                 }
2345
2346                 if ( count( $uniqueIndexes ) ) {
2347                         $clauses = []; // list WHERE clauses that each identify a single row
2348                         foreach ( $rows as $row ) {
2349                                 foreach ( $uniqueIndexes as $index ) {
2350                                         $index = is_array( $index ) ? $index : [ $index ]; // columns
2351                                         $rowKey = []; // unique key to this row
2352                                         foreach ( $index as $column ) {
2353                                                 $rowKey[$column] = $row[$column];
2354                                         }
2355                                         $clauses[] = $this->makeList( $rowKey, LIST_AND );
2356                                 }
2357                         }
2358                         $where = [ $this->makeList( $clauses, LIST_OR ) ];
2359                 } else {
2360                         $where = false;
2361                 }
2362
2363                 $useTrx = !$this->mTrxLevel;
2364                 if ( $useTrx ) {
2365                         $this->begin( $fname, self::TRANSACTION_INTERNAL );
2366                 }
2367                 try {
2368                         # Update any existing conflicting row(s)
2369                         if ( $where !== false ) {
2370                                 $ok = $this->update( $table, $set, $where, $fname );
2371                         } else {
2372                                 $ok = true;
2373                         }
2374                         # Now insert any non-conflicting row(s)
2375                         $ok = $this->insert( $table, $rows, $fname, [ 'IGNORE' ] ) && $ok;
2376                 } catch ( Exception $e ) {
2377                         if ( $useTrx ) {
2378                                 $this->rollback( $fname, self::FLUSHING_INTERNAL );
2379                         }
2380                         throw $e;
2381                 }
2382                 if ( $useTrx ) {
2383                         $this->commit( $fname, self::FLUSHING_INTERNAL );
2384                 }
2385
2386                 return $ok;
2387         }
2388
2389         public function deleteJoin( $delTable, $joinTable, $delVar, $joinVar, $conds,
2390                 $fname = __METHOD__
2391         ) {
2392                 if ( !$conds ) {
2393                         throw new DBUnexpectedError( $this, __METHOD__ . ' called with empty $conds' );
2394                 }
2395
2396                 $delTable = $this->tableName( $delTable );
2397                 $joinTable = $this->tableName( $joinTable );
2398                 $sql = "DELETE FROM $delTable WHERE $delVar IN (SELECT $joinVar FROM $joinTable ";
2399                 if ( $conds != '*' ) {
2400                         $sql .= 'WHERE ' . $this->makeList( $conds, LIST_AND );
2401                 }
2402                 $sql .= ')';
2403
2404                 $this->query( $sql, $fname );
2405         }
2406
2407         /**
2408          * Returns the size of a text field, or -1 for "unlimited"
2409          *
2410          * @param string $table
2411          * @param string $field
2412          * @return int
2413          */
2414         public function textFieldSize( $table, $field ) {
2415                 $table = $this->tableName( $table );
2416                 $sql = "SHOW COLUMNS FROM $table LIKE \"$field\";";
2417                 $res = $this->query( $sql, __METHOD__ );
2418                 $row = $this->fetchObject( $res );
2419
2420                 $m = [];
2421
2422                 if ( preg_match( '/\((.*)\)/', $row->Type, $m ) ) {
2423                         $size = $m[1];
2424                 } else {
2425                         $size = -1;
2426                 }
2427
2428                 return $size;
2429         }
2430
2431         /**
2432          * A string to insert into queries to show that they're low-priority, like
2433          * MySQL's LOW_PRIORITY. If no such feature exists, return an empty
2434          * string and nothing bad should happen.
2435          *
2436          * @return string Returns the text of the low priority option if it is
2437          *   supported, or a blank string otherwise
2438          */
2439         public function lowPriorityOption() {
2440                 return '';
2441         }
2442
2443         public function delete( $table, $conds, $fname = __METHOD__ ) {
2444                 if ( !$conds ) {
2445                         throw new DBUnexpectedError( $this, __METHOD__ . ' called with no conditions' );
2446                 }
2447
2448                 $table = $this->tableName( $table );
2449                 $sql = "DELETE FROM $table";
2450
2451                 if ( $conds != '*' ) {
2452                         if ( is_array( $conds ) ) {
2453                                 $conds = $this->makeList( $conds, LIST_AND );
2454                         }
2455                         $sql .= ' WHERE ' . $conds;
2456                 }
2457
2458                 return $this->query( $sql, $fname );
2459         }
2460
2461         public function insertSelect(
2462                 $destTable, $srcTable, $varMap, $conds,
2463                 $fname = __METHOD__, $insertOptions = [], $selectOptions = []
2464         ) {
2465                 if ( $this->cliMode ) {
2466                         // For massive migrations with downtime, we don't want to select everything
2467                         // into memory and OOM, so do all this native on the server side if possible.
2468                         return $this->nativeInsertSelect(
2469                                 $destTable,
2470                                 $srcTable,
2471                                 $varMap,
2472                                 $conds,
2473                                 $fname,
2474                                 $insertOptions,
2475                                 $selectOptions
2476                         );
2477                 }
2478
2479                 // For web requests, do a locking SELECT and then INSERT. This puts the SELECT burden
2480                 // on only the master (without needing row-based-replication). It also makes it easy to
2481                 // know how big the INSERT is going to be.
2482                 $fields = [];
2483                 foreach ( $varMap as $dstColumn => $sourceColumnOrSql ) {
2484                         $fields[] = $this->fieldNameWithAlias( $sourceColumnOrSql, $dstColumn );
2485                 }
2486                 $selectOptions[] = 'FOR UPDATE';
2487                 $res = $this->select( $srcTable, implode( ',', $fields ), $conds, $fname, $selectOptions );
2488                 if ( !$res ) {
2489                         return false;
2490                 }
2491
2492                 $rows = [];
2493                 foreach ( $res as $row ) {
2494                         $rows[] = (array)$row;
2495                 }
2496
2497                 return $this->insert( $destTable, $rows, $fname, $insertOptions );
2498         }
2499
2500         public function nativeInsertSelect( $destTable, $srcTable, $varMap, $conds,
2501                 $fname = __METHOD__,
2502                 $insertOptions = [], $selectOptions = []
2503         ) {
2504                 $destTable = $this->tableName( $destTable );
2505
2506                 if ( !is_array( $insertOptions ) ) {
2507                         $insertOptions = [ $insertOptions ];
2508                 }
2509
2510                 $insertOptions = $this->makeInsertOptions( $insertOptions );
2511
2512                 if ( !is_array( $selectOptions ) ) {
2513                         $selectOptions = [ $selectOptions ];
2514                 }
2515
2516                 list( $startOpts, $useIndex, $tailOpts, $ignoreIndex ) = $this->makeSelectOptions(
2517                         $selectOptions );
2518
2519                 if ( is_array( $srcTable ) ) {
2520                         $srcTable = implode( ',', array_map( [ &$this, 'tableName' ], $srcTable ) );
2521                 } else {
2522                         $srcTable = $this->tableName( $srcTable );
2523                 }
2524
2525                 $sql = "INSERT $insertOptions INTO $destTable (" . implode( ',', array_keys( $varMap ) ) . ')' .
2526                         " SELECT $startOpts " . implode( ',', $varMap ) .
2527                         " FROM $srcTable $useIndex $ignoreIndex ";
2528
2529                 if ( $conds != '*' ) {
2530                         if ( is_array( $conds ) ) {
2531                                 $conds = $this->makeList( $conds, LIST_AND );
2532                         }
2533                         $sql .= " WHERE $conds";
2534                 }
2535
2536                 $sql .= " $tailOpts";
2537
2538                 return $this->query( $sql, $fname );
2539         }
2540
2541         /**
2542          * Construct a LIMIT query with optional offset. This is used for query
2543          * pages. The SQL should be adjusted so that only the first $limit rows
2544          * are returned. If $offset is provided as well, then the first $offset
2545          * rows should be discarded, and the next $limit rows should be returned.
2546          * If the result of the query is not ordered, then the rows to be returned
2547          * are theoretically arbitrary.
2548          *
2549          * $sql is expected to be a SELECT, if that makes a difference.
2550          *
2551          * The version provided by default works in MySQL and SQLite. It will very
2552          * likely need to be overridden for most other DBMSes.
2553          *
2554          * @param string $sql SQL query we will append the limit too
2555          * @param int $limit The SQL limit
2556          * @param int|bool $offset The SQL offset (default false)
2557          * @throws DBUnexpectedError
2558          * @return string
2559          */
2560         public function limitResult( $sql, $limit, $offset = false ) {
2561                 if ( !is_numeric( $limit ) ) {
2562                         throw new DBUnexpectedError( $this, "Invalid non-numeric limit passed to limitResult()\n" );
2563                 }
2564
2565                 return "$sql LIMIT "
2566                         . ( ( is_numeric( $offset ) && $offset != 0 ) ? "{$offset}," : "" )
2567                         . "{$limit} ";
2568         }
2569
2570         public function unionSupportsOrderAndLimit() {
2571                 return true; // True for almost every DB supported
2572         }
2573
2574         public function unionQueries( $sqls, $all ) {
2575                 $glue = $all ? ') UNION ALL (' : ') UNION (';
2576
2577                 return '(' . implode( $glue, $sqls ) . ')';
2578         }
2579
2580         public function conditional( $cond, $trueVal, $falseVal ) {
2581                 if ( is_array( $cond ) ) {
2582                         $cond = $this->makeList( $cond, LIST_AND );
2583                 }
2584
2585                 return " (CASE WHEN $cond THEN $trueVal ELSE $falseVal END) ";
2586         }
2587
2588         public function strreplace( $orig, $old, $new ) {
2589                 return "REPLACE({$orig}, {$old}, {$new})";
2590         }
2591
2592         public function getServerUptime() {
2593                 return 0;
2594         }
2595
2596         public function wasDeadlock() {
2597                 return false;
2598         }
2599
2600         public function wasLockTimeout() {
2601                 return false;
2602         }
2603
2604         public function wasErrorReissuable() {
2605                 return false;
2606         }
2607
2608         public function wasReadOnlyError() {
2609                 return false;
2610         }
2611
2612         /**
2613          * Determines if the given query error was a connection drop
2614          * STUB
2615          *
2616          * @param integer|string $errno
2617          * @return bool
2618          */
2619         public function wasConnectionError( $errno ) {
2620                 return false;
2621         }
2622
2623         /**
2624          * Perform a deadlock-prone transaction.
2625          *
2626          * This function invokes a callback function to perform a set of write
2627          * queries. If a deadlock occurs during the processing, the transaction
2628          * will be rolled back and the callback function will be called again.
2629          *
2630          * Avoid using this method outside of Job or Maintenance classes.
2631          *
2632          * Usage:
2633          *   $dbw->deadlockLoop( callback, ... );
2634          *
2635          * Extra arguments are passed through to the specified callback function.
2636          * This method requires that no transactions are already active to avoid
2637          * causing premature commits or exceptions.
2638          *
2639          * Returns whatever the callback function returned on its successful,
2640          * iteration, or false on error, for example if the retry limit was
2641          * reached.
2642          *
2643          * @return mixed
2644          * @throws DBUnexpectedError
2645          * @throws Exception
2646          */
2647         public function deadlockLoop() {
2648                 $args = func_get_args();
2649                 $function = array_shift( $args );
2650                 $tries = self::DEADLOCK_TRIES;
2651
2652                 $this->begin( __METHOD__ );
2653
2654                 $retVal = null;
2655                 /** @var Exception $e */
2656                 $e = null;
2657                 do {
2658                         try {
2659                                 $retVal = call_user_func_array( $function, $args );
2660                                 break;
2661                         } catch ( DBQueryError $e ) {
2662                                 if ( $this->wasDeadlock() ) {
2663                                         // Retry after a randomized delay
2664                                         usleep( mt_rand( self::DEADLOCK_DELAY_MIN, self::DEADLOCK_DELAY_MAX ) );
2665                                 } else {
2666                                         // Throw the error back up
2667                                         throw $e;
2668                                 }
2669                         }
2670                 } while ( --$tries > 0 );
2671
2672                 if ( $tries <= 0 ) {
2673                         // Too many deadlocks; give up
2674                         $this->rollback( __METHOD__ );
2675                         throw $e;
2676                 } else {
2677                         $this->commit( __METHOD__ );
2678
2679                         return $retVal;
2680                 }
2681         }
2682
2683         public function masterPosWait( DBMasterPos $pos, $timeout ) {
2684                 # Real waits are implemented in the subclass.
2685                 return 0;
2686         }
2687
2688         public function getSlavePos() {
2689                 # Stub
2690                 return false;
2691         }
2692
2693         public function getMasterPos() {
2694                 # Stub
2695                 return false;
2696         }
2697
2698         public function serverIsReadOnly() {
2699                 return false;
2700         }
2701
2702         final public function onTransactionResolution( callable $callback, $fname = __METHOD__ ) {
2703                 if ( !$this->mTrxLevel ) {
2704                         throw new DBUnexpectedError( $this, "No transaction is active." );
2705                 }
2706                 $this->mTrxEndCallbacks[] = [ $callback, $fname ];
2707         }
2708
2709         final public function onTransactionIdle( callable $callback, $fname = __METHOD__ ) {
2710                 $this->mTrxIdleCallbacks[] = [ $callback, $fname ];
2711                 if ( !$this->mTrxLevel ) {
2712                         $this->runOnTransactionIdleCallbacks( self::TRIGGER_IDLE );
2713                 }
2714         }
2715
2716         final public function onTransactionPreCommitOrIdle( callable $callback, $fname = __METHOD__ ) {
2717                 if ( $this->mTrxLevel ) {
2718                         $this->mTrxPreCommitCallbacks[] = [ $callback, $fname ];
2719                 } else {
2720                         // If no transaction is active, then make one for this callback
2721                         $this->startAtomic( __METHOD__ );
2722                         try {
2723                                 call_user_func( $callback );
2724                                 $this->endAtomic( __METHOD__ );
2725                         } catch ( Exception $e ) {
2726                                 $this->rollback( __METHOD__, self::FLUSHING_INTERNAL );
2727                                 throw $e;
2728                         }
2729                 }
2730         }
2731
2732         final public function setTransactionListener( $name, callable $callback = null ) {
2733                 if ( $callback ) {
2734                         $this->mTrxRecurringCallbacks[$name] = $callback;
2735                 } else {
2736                         unset( $this->mTrxRecurringCallbacks[$name] );
2737                 }
2738         }
2739
2740         /**
2741          * Whether to disable running of post-COMMIT/ROLLBACK callbacks
2742          *
2743          * This method should not be used outside of Database/LoadBalancer
2744          *
2745          * @param bool $suppress
2746          * @since 1.28
2747          */
2748         final public function setTrxEndCallbackSuppression( $suppress ) {
2749                 $this->mTrxEndCallbacksSuppressed = $suppress;
2750         }
2751
2752         /**
2753          * Actually run and consume any "on transaction idle/resolution" callbacks.
2754          *
2755          * This method should not be used outside of Database/LoadBalancer
2756          *
2757          * @param integer $trigger IDatabase::TRIGGER_* constant
2758          * @since 1.20
2759          * @throws Exception
2760          */
2761         public function runOnTransactionIdleCallbacks( $trigger ) {
2762                 if ( $this->mTrxEndCallbacksSuppressed ) {
2763                         return;
2764                 }
2765
2766                 $autoTrx = $this->getFlag( DBO_TRX ); // automatic begin() enabled?
2767                 /** @var Exception $e */
2768                 $e = null; // first exception
2769                 do { // callbacks may add callbacks :)
2770                         $callbacks = array_merge(
2771                                 $this->mTrxIdleCallbacks,
2772                                 $this->mTrxEndCallbacks // include "transaction resolution" callbacks
2773                         );
2774                         $this->mTrxIdleCallbacks = []; // consumed (and recursion guard)
2775                         $this->mTrxEndCallbacks = []; // consumed (recursion guard)
2776                         foreach ( $callbacks as $callback ) {
2777                                 try {
2778                                         list( $phpCallback ) = $callback;
2779                                         $this->clearFlag( DBO_TRX ); // make each query its own transaction
2780                                         call_user_func_array( $phpCallback, [ $trigger ] );
2781                                         if ( $autoTrx ) {
2782                                                 $this->setFlag( DBO_TRX ); // restore automatic begin()
2783                                         } else {
2784                                                 $this->clearFlag( DBO_TRX ); // restore auto-commit
2785                                         }
2786                                 } catch ( Exception $ex ) {
2787                                         call_user_func( $this->errorLogger, $ex );
2788                                         $e = $e ?: $ex;
2789                                         // Some callbacks may use startAtomic/endAtomic, so make sure
2790                                         // their transactions are ended so other callbacks don't fail
2791                                         if ( $this->trxLevel() ) {
2792                                                 $this->rollback( __METHOD__, self::FLUSHING_INTERNAL );
2793                                         }
2794                                 }
2795                         }
2796                 } while ( count( $this->mTrxIdleCallbacks ) );
2797
2798                 if ( $e instanceof Exception ) {
2799                         throw $e; // re-throw any first exception
2800                 }
2801         }
2802
2803         /**
2804          * Actually run and consume any "on transaction pre-commit" callbacks.
2805          *
2806          * This method should not be used outside of Database/LoadBalancer
2807          *
2808          * @since 1.22
2809          * @throws Exception
2810          */
2811         public function runOnTransactionPreCommitCallbacks() {
2812                 $e = null; // first exception
2813                 do { // callbacks may add callbacks :)
2814                         $callbacks = $this->mTrxPreCommitCallbacks;
2815                         $this->mTrxPreCommitCallbacks = []; // consumed (and recursion guard)
2816                         foreach ( $callbacks as $callback ) {
2817                                 try {
2818                                         list( $phpCallback ) = $callback;
2819                                         call_user_func( $phpCallback );
2820                                 } catch ( Exception $ex ) {
2821                                         call_user_func( $this->errorLogger, $ex );
2822                                         $e = $e ?: $ex;
2823                                 }
2824                         }
2825                 } while ( count( $this->mTrxPreCommitCallbacks ) );
2826
2827                 if ( $e instanceof Exception ) {
2828                         throw $e; // re-throw any first exception
2829                 }
2830         }
2831
2832         /**
2833          * Actually run any "transaction listener" callbacks.
2834          *
2835          * This method should not be used outside of Database/LoadBalancer
2836          *
2837          * @param integer $trigger IDatabase::TRIGGER_* constant
2838          * @throws Exception
2839          * @since 1.20
2840          */
2841         public function runTransactionListenerCallbacks( $trigger ) {
2842                 if ( $this->mTrxEndCallbacksSuppressed ) {
2843                         return;
2844                 }
2845
2846                 /** @var Exception $e */
2847                 $e = null; // first exception
2848
2849                 foreach ( $this->mTrxRecurringCallbacks as $phpCallback ) {
2850                         try {
2851                                 $phpCallback( $trigger, $this );
2852                         } catch ( Exception $ex ) {
2853                                 call_user_func( $this->errorLogger, $ex );
2854                                 $e = $e ?: $ex;
2855                         }
2856                 }
2857
2858                 if ( $e instanceof Exception ) {
2859                         throw $e; // re-throw any first exception
2860                 }
2861         }
2862
2863         final public function startAtomic( $fname = __METHOD__ ) {
2864                 if ( !$this->mTrxLevel ) {
2865                         $this->begin( $fname, self::TRANSACTION_INTERNAL );
2866                         // If DBO_TRX is set, a series of startAtomic/endAtomic pairs will result
2867                         // in all changes being in one transaction to keep requests transactional.
2868                         if ( !$this->getFlag( DBO_TRX ) ) {
2869                                 $this->mTrxAutomaticAtomic = true;
2870                         }
2871                 }
2872
2873                 $this->mTrxAtomicLevels[] = $fname;
2874         }
2875
2876         final public function endAtomic( $fname = __METHOD__ ) {
2877                 if ( !$this->mTrxLevel ) {
2878                         throw new DBUnexpectedError( $this, "No atomic transaction is open (got $fname)." );
2879                 }
2880                 if ( !$this->mTrxAtomicLevels ||
2881                         array_pop( $this->mTrxAtomicLevels ) !== $fname
2882                 ) {
2883                         throw new DBUnexpectedError( $this, "Invalid atomic section ended (got $fname)." );
2884                 }
2885
2886                 if ( !$this->mTrxAtomicLevels && $this->mTrxAutomaticAtomic ) {
2887                         $this->commit( $fname, self::FLUSHING_INTERNAL );
2888                 }
2889         }
2890
2891         final public function doAtomicSection( $fname, callable $callback ) {
2892                 $this->startAtomic( $fname );
2893                 try {
2894                         $res = call_user_func_array( $callback, [ $this, $fname ] );
2895                 } catch ( Exception $e ) {
2896                         $this->rollback( $fname, self::FLUSHING_INTERNAL );
2897                         throw $e;
2898                 }
2899                 $this->endAtomic( $fname );
2900
2901                 return $res;
2902         }
2903
2904         final public function begin( $fname = __METHOD__, $mode = self::TRANSACTION_EXPLICIT ) {
2905                 // Protect against mismatched atomic section, transaction nesting, and snapshot loss
2906                 if ( $this->mTrxLevel ) {
2907                         if ( $this->mTrxAtomicLevels ) {
2908                                 $levels = implode( ', ', $this->mTrxAtomicLevels );
2909                                 $msg = "$fname: Got explicit BEGIN while atomic section(s) $levels are open.";
2910                                 throw new DBUnexpectedError( $this, $msg );
2911                         } elseif ( !$this->mTrxAutomatic ) {
2912                                 $msg = "$fname: Explicit transaction already active (from {$this->mTrxFname}).";
2913                                 throw new DBUnexpectedError( $this, $msg );
2914                         } else {
2915                                 // @TODO: make this an exception at some point
2916                                 $msg = "$fname: Implicit transaction already active (from {$this->mTrxFname}).";
2917                                 $this->queryLogger->error( $msg );
2918                                 return; // join the main transaction set
2919                         }
2920                 } elseif ( $this->getFlag( DBO_TRX ) && $mode !== self::TRANSACTION_INTERNAL ) {
2921                         // @TODO: make this an exception at some point
2922                         $msg = "$fname: Implicit transaction expected (DBO_TRX set).";
2923                         $this->queryLogger->error( $msg );
2924                         return; // let any writes be in the main transaction
2925                 }
2926
2927                 // Avoid fatals if close() was called
2928                 $this->assertOpen();
2929
2930                 $this->doBegin( $fname );
2931                 $this->mTrxTimestamp = microtime( true );
2932                 $this->mTrxFname = $fname;
2933                 $this->mTrxDoneWrites = false;
2934                 $this->mTrxAutomatic = ( $mode === self::TRANSACTION_INTERNAL );
2935                 $this->mTrxAutomaticAtomic = false;
2936                 $this->mTrxAtomicLevels = [];
2937                 $this->mTrxShortId = sprintf( '%06x', mt_rand( 0, 0xffffff ) );
2938                 $this->mTrxWriteDuration = 0.0;
2939                 $this->mTrxWriteQueryCount = 0;
2940                 $this->mTrxWriteAdjDuration = 0.0;
2941                 $this->mTrxWriteAdjQueryCount = 0;
2942                 $this->mTrxWriteCallers = [];
2943                 // First SELECT after BEGIN will establish the snapshot in REPEATABLE-READ.
2944                 // Get an estimate of the replica DB lag before then, treating estimate staleness
2945                 // as lag itself just to be safe
2946                 $status = $this->getApproximateLagStatus();
2947                 $this->mTrxReplicaLag = $status['lag'] + ( microtime( true ) - $status['since'] );
2948         }
2949
2950         /**
2951          * Issues the BEGIN command to the database server.
2952          *
2953          * @see DatabaseBase::begin()
2954          * @param string $fname
2955          */
2956         protected function doBegin( $fname ) {
2957                 $this->query( 'BEGIN', $fname );
2958                 $this->mTrxLevel = 1;
2959         }
2960
2961         final public function commit( $fname = __METHOD__, $flush = '' ) {
2962                 if ( $this->mTrxLevel && $this->mTrxAtomicLevels ) {
2963                         // There are still atomic sections open. This cannot be ignored
2964                         $levels = implode( ', ', $this->mTrxAtomicLevels );
2965                         throw new DBUnexpectedError(
2966                                 $this,
2967                                 "$fname: Got COMMIT while atomic sections $levels are still open."
2968                         );
2969                 }
2970
2971                 if ( $flush === self::FLUSHING_INTERNAL || $flush === self::FLUSHING_ALL_PEERS ) {
2972                         if ( !$this->mTrxLevel ) {
2973                                 return; // nothing to do
2974                         } elseif ( !$this->mTrxAutomatic ) {
2975                                 throw new DBUnexpectedError(
2976                                         $this,
2977                                         "$fname: Flushing an explicit transaction, getting out of sync."
2978                                 );
2979                         }
2980                 } else {
2981                         if ( !$this->mTrxLevel ) {
2982                                 $this->queryLogger->error( "$fname: No transaction to commit, something got out of sync." );
2983                                 return; // nothing to do
2984                         } elseif ( $this->mTrxAutomatic ) {
2985                                 // @TODO: make this an exception at some point
2986                                 $msg = "$fname: Explicit commit of implicit transaction.";
2987                                 $this->queryLogger->error( $msg );
2988                                 return; // wait for the main transaction set commit round
2989                         }
2990                 }
2991
2992                 // Avoid fatals if close() was called
2993                 $this->assertOpen();
2994
2995                 $this->runOnTransactionPreCommitCallbacks();
2996                 $writeTime = $this->pendingWriteQueryDuration( self::ESTIMATE_DB_APPLY );
2997                 $this->doCommit( $fname );
2998                 if ( $this->mTrxDoneWrites ) {
2999                         $this->mDoneWrites = microtime( true );
3000                         $this->trxProfiler->transactionWritingOut(
3001                                 $this->mServer, $this->mDBname, $this->mTrxShortId, $writeTime );
3002                 }
3003
3004                 $this->runOnTransactionIdleCallbacks( self::TRIGGER_COMMIT );
3005                 $this->runTransactionListenerCallbacks( self::TRIGGER_COMMIT );
3006         }
3007
3008         /**
3009          * Issues the COMMIT command to the database server.
3010          *
3011          * @see DatabaseBase::commit()
3012          * @param string $fname
3013          */
3014         protected function doCommit( $fname ) {
3015                 if ( $this->mTrxLevel ) {
3016                         $this->query( 'COMMIT', $fname );
3017                         $this->mTrxLevel = 0;
3018                 }
3019         }
3020
3021         final public function rollback( $fname = __METHOD__, $flush = '' ) {
3022                 if ( $flush === self::FLUSHING_INTERNAL || $flush === self::FLUSHING_ALL_PEERS ) {
3023                         if ( !$this->mTrxLevel ) {
3024                                 return; // nothing to do
3025                         }
3026                 } else {
3027                         if ( !$this->mTrxLevel ) {
3028                                 $this->queryLogger->error(
3029                                         "$fname: No transaction to rollback, something got out of sync." );
3030                                 return; // nothing to do
3031                         } elseif ( $this->getFlag( DBO_TRX ) ) {
3032                                 throw new DBUnexpectedError(
3033                                         $this,
3034                                         "$fname: Expected mass rollback of all peer databases (DBO_TRX set)."
3035                                 );
3036                         }
3037                 }
3038
3039                 // Avoid fatals if close() was called
3040                 $this->assertOpen();
3041
3042                 $this->doRollback( $fname );
3043                 $this->mTrxAtomicLevels = [];
3044                 if ( $this->mTrxDoneWrites ) {
3045                         $this->trxProfiler->transactionWritingOut(
3046                                 $this->mServer, $this->mDBname, $this->mTrxShortId );
3047                 }
3048
3049                 $this->mTrxIdleCallbacks = []; // clear
3050                 $this->mTrxPreCommitCallbacks = []; // clear
3051                 $this->runOnTransactionIdleCallbacks( self::TRIGGER_ROLLBACK );
3052                 $this->runTransactionListenerCallbacks( self::TRIGGER_ROLLBACK );
3053         }
3054
3055         /**
3056          * Issues the ROLLBACK command to the database server.
3057          *
3058          * @see DatabaseBase::rollback()
3059          * @param string $fname
3060          */
3061         protected function doRollback( $fname ) {
3062                 if ( $this->mTrxLevel ) {
3063                         # Disconnects cause rollback anyway, so ignore those errors
3064                         $ignoreErrors = true;
3065                         $this->query( 'ROLLBACK', $fname, $ignoreErrors );
3066                         $this->mTrxLevel = 0;
3067                 }
3068         }
3069
3070         public function flushSnapshot( $fname = __METHOD__ ) {
3071                 if ( $this->writesOrCallbacksPending() || $this->explicitTrxActive() ) {
3072                         // This only flushes transactions to clear snapshots, not to write data
3073                         $fnames = implode( ', ', $this->pendingWriteAndCallbackCallers() );
3074                         throw new DBUnexpectedError(
3075                                 $this,
3076                                 "$fname: Cannot COMMIT to clear snapshot because writes are pending ($fnames)."
3077                         );
3078                 }
3079
3080                 $this->commit( $fname, self::FLUSHING_INTERNAL );
3081         }
3082
3083         public function explicitTrxActive() {
3084                 return $this->mTrxLevel && ( $this->mTrxAtomicLevels || !$this->mTrxAutomatic );
3085         }
3086
3087         /**
3088          * Creates a new table with structure copied from existing table
3089          * Note that unlike most database abstraction functions, this function does not
3090          * automatically append database prefix, because it works at a lower
3091          * abstraction level.
3092          * The table names passed to this function shall not be quoted (this
3093          * function calls addIdentifierQuotes when needed).
3094          *
3095          * @param string $oldName Name of table whose structure should be copied
3096          * @param string $newName Name of table to be created
3097          * @param bool $temporary Whether the new table should be temporary
3098          * @param string $fname Calling function name
3099          * @throws RuntimeException
3100          * @return bool True if operation was successful
3101          */
3102         public function duplicateTableStructure( $oldName, $newName, $temporary = false,
3103                 $fname = __METHOD__
3104         ) {
3105                 throw new RuntimeException( __METHOD__ . ' is not implemented in descendant class' );
3106         }
3107
3108         function listTables( $prefix = null, $fname = __METHOD__ ) {
3109                 throw new RuntimeException( __METHOD__ . ' is not implemented in descendant class' );
3110         }
3111
3112         /**
3113          * Reset the views process cache set by listViews()
3114          * @since 1.22
3115          */
3116         final public function clearViewsCache() {
3117                 $this->allViews = null;
3118         }
3119
3120         /**
3121          * Lists all the VIEWs in the database
3122          *
3123          * For caching purposes the list of all views should be stored in
3124          * $this->allViews. The process cache can be cleared with clearViewsCache()
3125          *
3126          * @param string $prefix Only show VIEWs with this prefix, eg. unit_test_
3127          * @param string $fname Name of calling function
3128          * @throws RuntimeException
3129          * @return array
3130          * @since 1.22
3131          */
3132         public function listViews( $prefix = null, $fname = __METHOD__ ) {
3133                 throw new RuntimeException( __METHOD__ . ' is not implemented in descendant class' );
3134         }
3135
3136         /**
3137          * Differentiates between a TABLE and a VIEW
3138          *
3139          * @param string $name Name of the database-structure to test.
3140          * @throws RuntimeException
3141          * @return bool
3142          * @since 1.22
3143          */
3144         public function isView( $name ) {
3145                 throw new RuntimeException( __METHOD__ . ' is not implemented in descendant class' );
3146         }
3147
3148         public function timestamp( $ts = 0 ) {
3149                 $t = new ConvertableTimestamp( $ts );
3150                 // Let errors bubble up to avoid putting garbage in the DB
3151                 return $t->getTimestamp( TS_MW );
3152         }
3153
3154         public function timestampOrNull( $ts = null ) {
3155                 if ( is_null( $ts ) ) {
3156                         return null;
3157                 } else {
3158                         return $this->timestamp( $ts );
3159                 }
3160         }
3161
3162         /**
3163          * Take the result from a query, and wrap it in a ResultWrapper if
3164          * necessary. Boolean values are passed through as is, to indicate success
3165          * of write queries or failure.
3166          *
3167          * Once upon a time, DatabaseBase::query() returned a bare MySQL result
3168          * resource, and it was necessary to call this function to convert it to
3169          * a wrapper. Nowadays, raw database objects are never exposed to external
3170          * callers, so this is unnecessary in external code.
3171          *
3172          * @param bool|ResultWrapper|resource|object $result
3173          * @return bool|ResultWrapper
3174          */
3175         protected function resultObject( $result ) {
3176                 if ( !$result ) {
3177                         return false;
3178                 } elseif ( $result instanceof ResultWrapper ) {
3179                         return $result;
3180                 } elseif ( $result === true ) {
3181                         // Successful write query
3182                         return $result;
3183                 } else {
3184                         return new ResultWrapper( $this, $result );
3185                 }
3186         }
3187
3188         public function ping( &$rtt = null ) {
3189                 // Avoid hitting the server if it was hit recently
3190                 if ( $this->isOpen() && ( microtime( true ) - $this->lastPing ) < self::PING_TTL ) {
3191                         if ( !func_num_args() || $this->mRTTEstimate > 0 ) {
3192                                 $rtt = $this->mRTTEstimate;
3193                                 return true; // don't care about $rtt
3194                         }
3195                 }
3196
3197                 // This will reconnect if possible or return false if not
3198                 $this->clearFlag( DBO_TRX, self::REMEMBER_PRIOR );
3199                 $ok = ( $this->query( self::PING_QUERY, __METHOD__, true ) !== false );
3200                 $this->restoreFlags( self::RESTORE_PRIOR );
3201
3202                 if ( $ok ) {
3203                         $rtt = $this->mRTTEstimate;
3204                 }
3205
3206                 return $ok;
3207         }
3208
3209         /**
3210          * @return bool
3211          */
3212         protected function reconnect() {
3213                 $this->closeConnection();
3214                 $this->mOpened = false;
3215                 $this->mConn = false;
3216                 try {
3217                         $this->open( $this->mServer, $this->mUser, $this->mPassword, $this->mDBname );
3218                         $this->lastPing = microtime( true );
3219                         $ok = true;
3220                 } catch ( DBConnectionError $e ) {
3221                         $ok = false;
3222                 }
3223
3224                 return $ok;
3225         }
3226
3227         public function getSessionLagStatus() {
3228                 return $this->getTransactionLagStatus() ?: $this->getApproximateLagStatus();
3229         }
3230
3231         /**
3232          * Get the replica DB lag when the current transaction started
3233          *
3234          * This is useful when transactions might use snapshot isolation
3235          * (e.g. REPEATABLE-READ in innodb), so the "real" lag of that data
3236          * is this lag plus transaction duration. If they don't, it is still
3237          * safe to be pessimistic. This returns null if there is no transaction.
3238          *
3239          * @return array|null ('lag': seconds or false on error, 'since': UNIX timestamp of BEGIN)
3240          * @since 1.27
3241          */
3242         public function getTransactionLagStatus() {
3243                 return $this->mTrxLevel
3244                         ? [ 'lag' => $this->mTrxReplicaLag, 'since' => $this->trxTimestamp() ]
3245                         : null;
3246         }
3247
3248         /**
3249          * Get a replica DB lag estimate for this server
3250          *
3251          * @return array ('lag': seconds or false on error, 'since': UNIX timestamp of estimate)
3252          * @since 1.27
3253          */
3254         public function getApproximateLagStatus() {
3255                 return [
3256                         'lag'   => $this->getLBInfo( 'replica' ) ? $this->getLag() : 0,
3257                         'since' => microtime( true )
3258                 ];
3259         }
3260
3261         /**
3262          * Merge the result of getSessionLagStatus() for several DBs
3263          * using the most pessimistic values to estimate the lag of
3264          * any data derived from them in combination
3265          *
3266          * This is information is useful for caching modules
3267          *
3268          * @see WANObjectCache::set()
3269          * @see WANObjectCache::getWithSetCallback()
3270          *
3271          * @param IDatabase $db1
3272          * @param IDatabase ...
3273          * @return array Map of values:
3274          *   - lag: highest lag of any of the DBs or false on error (e.g. replication stopped)
3275          *   - since: oldest UNIX timestamp of any of the DB lag estimates
3276          *   - pending: whether any of the DBs have uncommitted changes
3277          * @since 1.27
3278          */
3279         public static function getCacheSetOptions( IDatabase $db1 ) {
3280                 $res = [ 'lag' => 0, 'since' => INF, 'pending' => false ];
3281                 foreach ( func_get_args() as $db ) {
3282                         /** @var IDatabase $db */
3283                         $status = $db->getSessionLagStatus();
3284                         if ( $status['lag'] === false ) {
3285                                 $res['lag'] = false;
3286                         } elseif ( $res['lag'] !== false ) {
3287                                 $res['lag'] = max( $res['lag'], $status['lag'] );
3288                         }
3289                         $res['since'] = min( $res['since'], $status['since'] );
3290                         $res['pending'] = $res['pending'] ?: $db->writesPending();
3291                 }
3292
3293                 return $res;
3294         }
3295
3296         public function getLag() {
3297                 return 0;
3298         }
3299
3300         function maxListLen() {
3301                 return 0;
3302         }
3303
3304         public function encodeBlob( $b ) {
3305                 return $b;
3306         }
3307
3308         public function decodeBlob( $b ) {
3309                 if ( $b instanceof Blob ) {
3310                         $b = $b->fetch();
3311                 }
3312                 return $b;
3313         }
3314
3315         public function setSessionOptions( array $options ) {
3316         }
3317
3318         /**
3319          * Read and execute SQL commands from a file.
3320          *
3321          * Returns true on success, error string or exception on failure (depending
3322          * on object's error ignore settings).
3323          *
3324          * @param string $filename File name to open
3325          * @param bool|callable $lineCallback Optional function called before reading each line
3326          * @param bool|callable $resultCallback Optional function called for each MySQL result
3327          * @param bool|string $fname Calling function name or false if name should be
3328          *   generated dynamically using $filename
3329          * @param bool|callable $inputCallback Optional function called for each
3330          *   complete line sent
3331          * @return bool|string
3332          * @throws Exception
3333          */
3334         public function sourceFile(
3335                 $filename, $lineCallback = false, $resultCallback = false, $fname = false, $inputCallback = false
3336         ) {
3337                 MediaWiki\suppressWarnings();
3338                 $fp = fopen( $filename, 'r' );
3339                 MediaWiki\restoreWarnings();
3340
3341                 if ( false === $fp ) {
3342                         throw new RuntimeException( "Could not open \"{$filename}\".\n" );
3343                 }
3344
3345                 if ( !$fname ) {
3346                         $fname = __METHOD__ . "( $filename )";
3347                 }
3348
3349                 try {
3350                         $error = $this->sourceStream( $fp, $lineCallback, $resultCallback, $fname, $inputCallback );
3351                 } catch ( Exception $e ) {
3352                         fclose( $fp );
3353                         throw $e;
3354                 }
3355
3356                 fclose( $fp );
3357
3358                 return $error;
3359         }
3360
3361         public function setSchemaVars( $vars ) {
3362                 $this->mSchemaVars = $vars;
3363         }
3364
3365         /**
3366          * Read and execute commands from an open file handle.
3367          *
3368          * Returns true on success, error string or exception on failure (depending
3369          * on object's error ignore settings).
3370          *
3371          * @param resource $fp File handle
3372          * @param bool|callable $lineCallback Optional function called before reading each query
3373          * @param bool|callable $resultCallback Optional function called for each MySQL result
3374          * @param string $fname Calling function name
3375          * @param bool|callable $inputCallback Optional function called for each complete query sent
3376          * @return bool|string
3377          */
3378         public function sourceStream( $fp, $lineCallback = false, $resultCallback = false,
3379                 $fname = __METHOD__, $inputCallback = false
3380         ) {
3381                 $cmd = '';
3382
3383                 while ( !feof( $fp ) ) {
3384                         if ( $lineCallback ) {
3385                                 call_user_func( $lineCallback );
3386                         }
3387
3388                         $line = trim( fgets( $fp ) );
3389
3390                         if ( $line == '' ) {
3391                                 continue;
3392                         }
3393
3394                         if ( '-' == $line[0] && '-' == $line[1] ) {
3395                                 continue;
3396                         }
3397
3398                         if ( $cmd != '' ) {
3399                                 $cmd .= ' ';
3400                         }
3401
3402                         $done = $this->streamStatementEnd( $cmd, $line );
3403
3404                         $cmd .= "$line\n";
3405
3406                         if ( $done || feof( $fp ) ) {
3407                                 $cmd = $this->replaceVars( $cmd );
3408
3409                                 if ( ( $inputCallback && call_user_func( $inputCallback, $cmd ) ) || !$inputCallback ) {
3410                                         $res = $this->query( $cmd, $fname );
3411
3412                                         if ( $resultCallback ) {
3413                                                 call_user_func( $resultCallback, $res, $this );
3414                                         }
3415
3416                                         if ( false === $res ) {
3417                                                 $err = $this->lastError();
3418
3419                                                 return "Query \"{$cmd}\" failed with error code \"$err\".\n";
3420                                         }
3421                                 }
3422                                 $cmd = '';
3423                         }
3424                 }
3425
3426                 return true;
3427         }
3428
3429         /**
3430          * Called by sourceStream() to check if we've reached a statement end
3431          *
3432          * @param string $sql SQL assembled so far
3433          * @param string $newLine New line about to be added to $sql
3434          * @return bool Whether $newLine contains end of the statement
3435          */
3436         public function streamStatementEnd( &$sql, &$newLine ) {
3437                 if ( $this->delimiter ) {
3438                         $prev = $newLine;
3439                         $newLine = preg_replace( '/' . preg_quote( $this->delimiter, '/' ) . '$/', '', $newLine );
3440                         if ( $newLine != $prev ) {
3441                                 return true;
3442                         }
3443                 }
3444
3445                 return false;
3446         }
3447
3448         /**
3449          * Database independent variable replacement. Replaces a set of variables
3450          * in an SQL statement with their contents as given by $this->getSchemaVars().
3451          *
3452          * Supports '{$var}' `{$var}` and / *$var* / (without the spaces) style variables.
3453          *
3454          * - '{$var}' should be used for text and is passed through the database's
3455          *   addQuotes method.
3456          * - `{$var}` should be used for identifiers (e.g. table and database names).
3457          *   It is passed through the database's addIdentifierQuotes method which
3458          *   can be overridden if the database uses something other than backticks.
3459          * - / *_* / or / *$wgDBprefix* / passes the name that follows through the
3460          *   database's tableName method.
3461          * - / *i* / passes the name that follows through the database's indexName method.
3462          * - In all other cases, / *$var* / is left unencoded. Except for table options,
3463          *   its use should be avoided. In 1.24 and older, string encoding was applied.
3464          *
3465          * @param string $ins SQL statement to replace variables in
3466          * @return string The new SQL statement with variables replaced
3467          */
3468         protected function replaceVars( $ins ) {
3469                 $vars = $this->getSchemaVars();
3470                 return preg_replace_callback(
3471                         '!
3472                                 /\* (\$wgDBprefix|[_i]) \*/ (\w*) | # 1-2. tableName, indexName
3473                                 \'\{\$ (\w+) }\'                  | # 3. addQuotes
3474                                 `\{\$ (\w+) }`                    | # 4. addIdentifierQuotes
3475                                 /\*\$ (\w+) \*/                     # 5. leave unencoded
3476                         !x',
3477                         function ( $m ) use ( $vars ) {
3478                                 // Note: Because of <https://bugs.php.net/bug.php?id=51881>,
3479                                 // check for both nonexistent keys *and* the empty string.
3480                                 if ( isset( $m[1] ) && $m[1] !== '' ) {
3481                                         if ( $m[1] === 'i' ) {
3482                                                 return $this->indexName( $m[2] );
3483                                         } else {
3484                                                 return $this->tableName( $m[2] );
3485                                         }
3486                                 } elseif ( isset( $m[3] ) && $m[3] !== '' && array_key_exists( $m[3], $vars ) ) {
3487                                         return $this->addQuotes( $vars[$m[3]] );
3488                                 } elseif ( isset( $m[4] ) && $m[4] !== '' && array_key_exists( $m[4], $vars ) ) {
3489                                         return $this->addIdentifierQuotes( $vars[$m[4]] );
3490                                 } elseif ( isset( $m[5] ) && $m[5] !== '' && array_key_exists( $m[5], $vars ) ) {
3491                                         return $vars[$m[5]];
3492                                 } else {
3493                                         return $m[0];
3494                                 }
3495                         },
3496                         $ins
3497                 );
3498         }
3499
3500         /**
3501          * Get schema variables. If none have been set via setSchemaVars(), then
3502          * use some defaults from the current object.
3503          *
3504          * @return array
3505          */
3506         protected function getSchemaVars() {
3507                 if ( $this->mSchemaVars ) {
3508                         return $this->mSchemaVars;
3509                 } else {
3510                         return $this->getDefaultSchemaVars();
3511                 }
3512         }
3513
3514         /**
3515          * Get schema variables to use if none have been set via setSchemaVars().
3516          *
3517          * Override this in derived classes to provide variables for tables.sql
3518          * and SQL patch files.
3519          *
3520          * @return array
3521          */
3522         protected function getDefaultSchemaVars() {
3523                 return [];
3524         }
3525
3526         public function lockIsFree( $lockName, $method ) {
3527                 return true;
3528         }
3529
3530         public function lock( $lockName, $method, $timeout = 5 ) {
3531                 $this->mNamedLocksHeld[$lockName] = 1;
3532
3533                 return true;
3534         }
3535
3536         public function unlock( $lockName, $method ) {
3537                 unset( $this->mNamedLocksHeld[$lockName] );
3538
3539                 return true;
3540         }
3541
3542         public function getScopedLockAndFlush( $lockKey, $fname, $timeout ) {
3543                 if ( $this->writesOrCallbacksPending() ) {
3544                         // This only flushes transactions to clear snapshots, not to write data
3545                         $fnames = implode( ', ', $this->pendingWriteAndCallbackCallers() );
3546                         throw new DBUnexpectedError(
3547                                 $this,
3548                                 "$fname: Cannot COMMIT to clear snapshot because writes are pending ($fnames)."
3549                         );
3550                 }
3551
3552                 if ( !$this->lock( $lockKey, $fname, $timeout ) ) {
3553                         return null;
3554                 }
3555
3556                 $unlocker = new ScopedCallback( function () use ( $lockKey, $fname ) {
3557                         if ( $this->trxLevel() ) {
3558                                 // There is a good chance an exception was thrown, causing any early return
3559                                 // from the caller. Let any error handler get a chance to issue rollback().
3560                                 // If there isn't one, let the error bubble up and trigger server-side rollback.
3561                                 $this->onTransactionResolution(
3562                                         function () use ( $lockKey, $fname ) {
3563                                                 $this->unlock( $lockKey, $fname );
3564                                         },
3565                                         $fname
3566                                 );
3567                         } else {
3568                                 $this->unlock( $lockKey, $fname );
3569                         }
3570                 } );
3571
3572                 $this->commit( $fname, self::FLUSHING_INTERNAL );
3573
3574                 return $unlocker;
3575         }
3576
3577         public function namedLocksEnqueue() {
3578                 return false;
3579         }
3580
3581         /**
3582          * Lock specific tables
3583          *
3584          * @param array $read Array of tables to lock for read access
3585          * @param array $write Array of tables to lock for write access
3586          * @param string $method Name of caller
3587          * @param bool $lowPriority Whether to indicate writes to be LOW PRIORITY
3588          * @return bool
3589          */
3590         public function lockTables( $read, $write, $method, $lowPriority = true ) {
3591                 return true;
3592         }
3593
3594         /**
3595          * Unlock specific tables
3596          *
3597          * @param string $method The caller
3598          * @return bool
3599          */
3600         public function unlockTables( $method ) {
3601                 return true;
3602         }
3603
3604         /**
3605          * Delete a table
3606          * @param string $tableName
3607          * @param string $fName
3608          * @return bool|ResultWrapper
3609          * @since 1.18
3610          */
3611         public function dropTable( $tableName, $fName = __METHOD__ ) {
3612                 if ( !$this->tableExists( $tableName, $fName ) ) {
3613                         return false;
3614                 }
3615                 $sql = "DROP TABLE " . $this->tableName( $tableName );
3616                 if ( $this->cascadingDeletes() ) {
3617                         $sql .= " CASCADE";
3618                 }
3619
3620                 return $this->query( $sql, $fName );
3621         }
3622
3623         /**
3624          * Get search engine class. All subclasses of this need to implement this
3625          * if they wish to use searching.
3626          *
3627          * @return string
3628          */
3629         public function getSearchEngine() {
3630                 return 'SearchEngineDummy';
3631         }
3632
3633         public function getInfinity() {
3634                 return 'infinity';
3635         }
3636
3637         public function encodeExpiry( $expiry ) {
3638                 return ( $expiry == '' || $expiry == 'infinity' || $expiry == $this->getInfinity() )
3639                         ? $this->getInfinity()
3640                         : $this->timestamp( $expiry );
3641         }
3642
3643         public function decodeExpiry( $expiry, $format = TS_MW ) {
3644                 if ( $expiry == '' || $expiry == 'infinity' || $expiry == $this->getInfinity() ) {
3645                         return 'infinity';
3646                 }
3647
3648                 try {
3649                         $t = new ConvertableTimestamp( $expiry );
3650
3651                         return $t->getTimestamp( $format );
3652                 } catch ( TimestampException $e ) {
3653                         return false;
3654                 }
3655         }
3656
3657         public function setBigSelects( $value = true ) {
3658                 // no-op
3659         }
3660
3661         public function isReadOnly() {
3662                 return ( $this->getReadOnlyReason() !== false );
3663         }
3664
3665         /**
3666          * @return string|bool Reason this DB is read-only or false if it is not
3667          */
3668         protected function getReadOnlyReason() {
3669                 $reason = $this->getLBInfo( 'readOnlyReason' );
3670
3671                 return is_string( $reason ) ? $reason : false;
3672         }
3673
3674         public function setTableAliases( array $aliases ) {
3675                 $this->tableAliases = $aliases;
3676         }
3677
3678         /**
3679          * @since 1.19
3680          * @return string
3681          */
3682         public function __toString() {
3683                 return (string)$this->mConn;
3684         }
3685
3686         /**
3687          * Run a few simple sanity checks
3688          */
3689         public function __destruct() {
3690                 if ( $this->mTrxLevel && $this->mTrxDoneWrites ) {
3691                         trigger_error( "Uncommitted DB writes (transaction from {$this->mTrxFname})." );
3692                 }
3693
3694                 $danglingWriters = $this->pendingWriteAndCallbackCallers();
3695                 if ( $danglingWriters ) {
3696                         $fnames = implode( ', ', $danglingWriters );
3697                         trigger_error( "DB transaction writes or callbacks still pending ($fnames)." );
3698                 }
3699         }
3700 }
3701
3702 /**
3703  * @since 1.27
3704  */
3705 abstract class Database extends DatabaseBase {
3706         // B/C until nothing type hints for DatabaseBase
3707         // @TODO: finish renaming DatabaseBase => Database
3708 }