includes/db/Database.php

   1 <?php
   2 /**
   3  * @defgroup Database Database
   4  *
   5  * This file deals with database interface functions
   6  * and query specifics/optimisations.
   7  *
   8  * This program is free software; you can redistribute it and/or modify
   9  * it under the terms of the GNU General Public License as published by
  10  * the Free Software Foundation; either version 2 of the License, or
  11  * (at your option) any later version.
  12  *
  13  * This program is distributed in the hope that it will be useful,
  14  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  15  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
  16  * GNU General Public License for more details.
  17  *
  18  * You should have received a copy of the GNU General Public License along
  19  * with this program; if not, write to the Free Software Foundation, Inc.,
  20  * 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
  21  * http://www.gnu.org/copyleft/gpl.html
  22  *
  23  * @file
  24  * @ingroup Database
  25  */
  26 use Psr\Log\LoggerAwareInterface;
  27 use Psr\Log\LoggerInterface;
  28
  29 /**
  30  * Database abstraction object
  31  * @ingroup Database
  32  */
  33 abstract class DatabaseBase implements IDatabase, LoggerAwareInterface {
  34         /** Number of times to re-try an operation in case of deadlock */
  35         const DEADLOCK_TRIES = 4;
  36         /** Minimum time to wait before retry, in microseconds */
  37         const DEADLOCK_DELAY_MIN = 500000;
  38         /** Maximum time to wait before retry */
  39         const DEADLOCK_DELAY_MAX = 1500000;
  40
  41         /** How long before it is worth doing a dummy query to test the connection */
  42         const PING_TTL = 1.0;
  43         const PING_QUERY = 'SELECT 1 AS ping';
  44
  45         const TINY_WRITE_SEC = .010;
  46         const SLOW_WRITE_SEC = .500;
  47         const SMALL_WRITE_ROWS = 100;
  48
  49         /** @var string SQL query */
  50         protected $mLastQuery = '';
  51         /** @var bool */
  52         protected $mDoneWrites = false;
  53         /** @var string|bool */
  54         protected $mPHPError = false;
  55         /** @var string */
  56         protected $mServer;
  57         /** @var string */
  58         protected $mUser;
  59         /** @var string */
  60         protected $mPassword;
  61         /** @var string */
  62         protected $mDBname;
  63         /** @var bool */
  64         protected $cliMode;
  65
  66         /** @var BagOStuff APC cache */
  67         protected $srvCache;
  68         /** @var LoggerInterface */
  69         protected $connLogger;
  70         /** @var LoggerInterface */
  71         protected $queryLogger;
  72         /** @var callback Error logging callback */
  73         protected $errorLogger;
  74
  75         /** @var resource Database connection */
  76         protected $mConn = null;
  77         /** @var bool */
  78         protected $mOpened = false;
  79
  80         /** @var array[] List of (callable, method name) */
  81         protected $mTrxIdleCallbacks = [];
  82         /** @var array[] List of (callable, method name) */
  83         protected $mTrxPreCommitCallbacks = [];
  84         /** @var array[] List of (callable, method name) */
  85         protected $mTrxEndCallbacks = [];
  86         /** @var array[] Map of (name => (callable, method name)) */
  87         protected $mTrxRecurringCallbacks = [];
  88         /** @var bool Whether to suppress triggering of transaction end callbacks */
  89         protected $mTrxEndCallbacksSuppressed = false;
  90
  91         /** @var string */
  92         protected $mTablePrefix;
  93         /** @var string */
  94         protected $mSchema;
  95         /** @var integer */
  96         protected $mFlags;
  97         /** @var bool */
  98         protected $mForeign;
  99         /** @var array */
 100         protected $mLBInfo = [];
 101         /** @var bool|null */
 102         protected $mDefaultBigSelects = null;
 103         /** @var array|bool */
 104         protected $mSchemaVars = false;
 105         /** @var array */
 106         protected $mSessionVars = [];
 107         /** @var array|null */
 108         protected $preparedArgs;
 109         /** @var string|bool|null Stashed value of html_errors INI setting */
 110         protected $htmlErrors;
 111         /** @var string */
 112         protected $delimiter = ';';
 113
 114         /**
 115          * Either 1 if a transaction is active or 0 otherwise.
 116          * The other Trx fields may not be meaningfull if this is 0.
 117          *
 118          * @var int
 119          */
 120         protected $mTrxLevel = 0;
 121         /**
 122          * Either a short hexidecimal string if a transaction is active or ""
 123          *
 124          * @var string
 125          * @see DatabaseBase::mTrxLevel
 126          */
 127         protected $mTrxShortId = '';
 128         /**
 129          * The UNIX time that the transaction started. Callers can assume that if
 130          * snapshot isolation is used, then the data is *at least* up to date to that
 131          * point (possibly more up-to-date since the first SELECT defines the snapshot).
 132          *
 133          * @var float|null
 134          * @see DatabaseBase::mTrxLevel
 135          */
 136         private $mTrxTimestamp = null;
 137         /** @var float Lag estimate at the time of BEGIN */
 138         private $mTrxReplicaLag = null;
 139         /**
 140          * Remembers the function name given for starting the most recent transaction via begin().
 141          * Used to provide additional context for error reporting.
 142          *
 143          * @var string
 144          * @see DatabaseBase::mTrxLevel
 145          */
 146         private $mTrxFname = null;
 147         /**
 148          * Record if possible write queries were done in the last transaction started
 149          *
 150          * @var bool
 151          * @see DatabaseBase::mTrxLevel
 152          */
 153         private $mTrxDoneWrites = false;
 154         /**
 155          * Record if the current transaction was started implicitly due to DBO_TRX being set.
 156          *
 157          * @var bool
 158          * @see DatabaseBase::mTrxLevel
 159          */
 160         private $mTrxAutomatic = false;
 161         /**
 162          * Array of levels of atomicity within transactions
 163          *
 164          * @var array
 165          */
 166         private $mTrxAtomicLevels = [];
 167         /**
 168          * Record if the current transaction was started implicitly by DatabaseBase::startAtomic
 169          *
 170          * @var bool
 171          */
 172         private $mTrxAutomaticAtomic = false;
 173         /**
 174          * Track the write query callers of the current transaction
 175          *
 176          * @var string[]
 177          */
 178         private $mTrxWriteCallers = [];
 179         /**
 180          * @var float Seconds spent in write queries for the current transaction
 181          */
 182         private $mTrxWriteDuration = 0.0;
 183         /**
 184          * @var integer Number of write queries for the current transaction
 185          */
 186         private $mTrxWriteQueryCount = 0;
 187         /**
 188          * @var float Like mTrxWriteQueryCount but excludes lock-bound, easy to replicate, queries
 189          */
 190         private $mTrxWriteAdjDuration = 0.0;
 191         /**
 192          * @var integer Number of write queries counted in mTrxWriteAdjDuration
 193          */
 194         private $mTrxWriteAdjQueryCount = 0;
 195         /**
 196          * @var float RTT time estimate
 197          */
 198         private $mRTTEstimate = 0.0;
 199
 200         /** @var array Map of (name => 1) for locks obtained via lock() */
 201         private $mNamedLocksHeld = [];
 202
 203         /** @var IDatabase|null Lazy handle to the master DB this server replicates from */
 204         private $lazyMasterHandle;
 205
 206         /**
 207          * @since 1.21
 208          * @var resource File handle for upgrade
 209          */
 210         protected $fileHandle = null;
 211
 212         /**
 213          * @since 1.22
 214          * @var string[] Process cache of VIEWs names in the database
 215          */
 216         protected $allViews = null;
 217
 218         /** @var float UNIX timestamp */
 219         protected $lastPing = 0.0;
 220
 221         /** @var int[] Prior mFlags values */
 222         private $priorFlags = [];
 223
 224         /** @var Profiler */
 225         protected $profiler;
 226         /** @var TransactionProfiler */
 227         protected $trxProfiler;
 228
 229         /**
 230          * Constructor.
 231          *
 232          * FIXME: It is possible to construct a Database object with no associated
 233          * connection object, by specifying no parameters to __construct(). This
 234          * feature is deprecated and should be removed.
 235          *
 236          * IDatabase classes should not be constructed directly in external
 237          * code. DatabaseBase::factory() should be used instead.
 238          *
 239          * @param array $params Parameters passed from DatabaseBase::factory()
 240          */
 241         function __construct( array $params ) {
 242                 $server = $params['host'];
 243                 $user = $params['user'];
 244                 $password = $params['password'];
 245                 $dbName = $params['dbname'];
 246                 $flags = $params['flags'];
 247
 248                 $this->mSchema = $params['schema'];
 249                 $this->mTablePrefix = $params['tablePrefix'];
 250
 251                 $this->cliMode = isset( $params['cliMode'] )
 252                         ? $params['cliMode']
 253                         : ( PHP_SAPI === 'cli' );
 254
 255                 $this->mFlags = $flags;
 256                 if ( $this->mFlags & DBO_DEFAULT ) {
 257                         if ( $this->cliMode ) {
 258                                 $this->mFlags &= ~DBO_TRX;
 259                         } else {
 260                                 $this->mFlags |= DBO_TRX;
 261                         }
 262                 }
 263
 264                 $this->mSessionVars = $params['variables'];
 265
 266                 $this->mForeign = $params['foreign'];
 267
 268                 $this->srvCache = isset( $params['srvCache'] )
 269                         ? $params['srvCache']
 270                         : new EmptyBagOStuff();
 271
 272                 $this->profiler = isset( $params['profiler'] )
 273                         ? $params['profiler']
 274                         : Profiler::instance(); // @TODO: remove global state
 275                 $this->trxProfiler = isset( $params['trxProfiler'] )
 276                         ? $params['trxProfiler']
 277                         : new TransactionProfiler();
 278                 $this->connLogger = isset( $params['connLogger'] )
 279                         ? $params['connLogger']
 280                         : new \Psr\Log\NullLogger();
 281                 $this->queryLogger = isset( $params['queryLogger'] )
 282                         ? $params['queryLogger']
 283                         : new \Psr\Log\NullLogger();
 284
 285                 if ( $user ) {
 286                         $this->open( $server, $user, $password, $dbName );
 287                 }
 288         }
 289
 290         /**
 291          * Given a DB type, construct the name of the appropriate child class of
 292          * IDatabase. This is designed to replace all of the manual stuff like:
 293          *    $class = 'Database' . ucfirst( strtolower( $dbType ) );
 294          * as well as validate against the canonical list of DB types we have
 295          *
 296          * This factory function is mostly useful for when you need to connect to a
 297          * database other than the MediaWiki default (such as for external auth,
 298          * an extension, et cetera). Do not use this to connect to the MediaWiki
 299          * database. Example uses in core:
 300          * @see LoadBalancer::reallyOpenConnection()
 301          * @see ForeignDBRepo::getMasterDB()
 302          * @see WebInstallerDBConnect::execute()
 303          *
 304          * @since 1.18
 305          *
 306          * @param string $dbType A possible DB type
 307          * @param array $p An array of options to pass to the constructor.
 308          *    Valid options are: host, user, password, dbname, flags, tablePrefix, schema, driver
 309          * @return IDatabase|null If the database driver or extension cannot be found
 310          * @throws InvalidArgumentException If the database driver or extension cannot be found
 311          */
 312         final public static function factory( $dbType, $p = [] ) {
 313                 global $wgCommandLineMode;
 314
 315                 $canonicalDBTypes = [
 316                         'mysql' => [ 'mysqli', 'mysql' ],
 317                         'postgres' => [],
 318                         'sqlite' => [],
 319                         'oracle' => [],
 320                         'mssql' => [],
 321                 ];
 322
 323                 $driver = false;
 324                 $dbType = strtolower( $dbType );
 325                 if ( isset( $canonicalDBTypes[$dbType] ) && $canonicalDBTypes[$dbType] ) {
 326                         $possibleDrivers = $canonicalDBTypes[$dbType];
 327                         if ( !empty( $p['driver'] ) ) {
 328                                 if ( in_array( $p['driver'], $possibleDrivers ) ) {
 329                                         $driver = $p['driver'];
 330                                 } else {
 331                                         throw new InvalidArgumentException( __METHOD__ .
 332                                                 " type '$dbType' does not support driver '{$p['driver']}'" );
 333                                 }
 334                         } else {
 335                                 foreach ( $possibleDrivers as $posDriver ) {
 336                                         if ( extension_loaded( $posDriver ) ) {
 337                                                 $driver = $posDriver;
 338                                                 break;
 339                                         }
 340                                 }
 341                         }
 342                 } else {
 343                         $driver = $dbType;
 344                 }
 345                 if ( $driver === false ) {
 346                         throw new InvalidArgumentException( __METHOD__ .
 347                                 " no viable database extension found for type '$dbType'" );
 348                 }
 349
 350                 // Determine schema defaults. Currently Microsoft SQL Server uses $wgDBmwschema,
 351                 // and everything else doesn't use a schema (e.g. null)
 352                 // Although postgres and oracle support schemas, we don't use them (yet)
 353                 // to maintain backwards compatibility
 354                 $defaultSchemas = [
 355                         'mssql' => 'get from global',
 356                 ];
 357
 358                 $class = 'Database' . ucfirst( $driver );
 359                 if ( class_exists( $class ) && is_subclass_of( $class, 'IDatabase' ) ) {
 360                         // Resolve some defaults for b/c
 361                         $p['host'] = isset( $p['host'] ) ? $p['host'] : false;
 362                         $p['user'] = isset( $p['user'] ) ? $p['user'] : false;
 363                         $p['password'] = isset( $p['password'] ) ? $p['password'] : false;
 364                         $p['dbname'] = isset( $p['dbname'] ) ? $p['dbname'] : false;
 365                         $p['flags'] = isset( $p['flags'] ) ? $p['flags'] : 0;
 366                         $p['variables'] = isset( $p['variables'] ) ? $p['variables'] : [];
 367                         $p['tablePrefix'] = isset( $p['tablePrefix'] ) ? $p['tablePrefix'] : '';
 368                         if ( !isset( $p['schema'] ) ) {
 369                                 $p['schema'] = isset( $defaultSchemas[$dbType] ) ? $defaultSchemas[$dbType] : null;
 370                         }
 371                         $p['foreign'] = isset( $p['foreign'] ) ? $p['foreign'] : false;
 372                         $p['cliMode'] = $wgCommandLineMode;
 373
 374                         $conn = new $class( $p );
 375                         if ( isset( $p['connLogger'] ) ) {
 376                                 $conn->connLogger = $p['connLogger'];
 377                         }
 378                         if ( isset( $p['queryLogger'] ) ) {
 379                                 $conn->queryLogger = $p['queryLogger'];
 380                         }
 381                         if ( isset( $p['errorLogger'] ) ) {
 382                                 $conn->errorLogger = $p['errorLogger'];
 383                         } else {
 384                                 $conn->errorLogger = [ MWExceptionHandler::class, 'logException' ];
 385                         }
 386                 } else {
 387                         $conn = null;
 388                 }
 389
 390                 return $conn;
 391         }
 392
 393         public function setLogger( LoggerInterface $logger ) {
 394                 $this->queryLogger = $logger;
 395         }
 396
 397         public function getServerInfo() {
 398                 return $this->getServerVersion();
 399         }
 400
 401         /**
 402          * @return string Command delimiter used by this database engine
 403          */
 404         public function getDelimiter() {
 405                 return $this->delimiter;
 406         }
 407
 408         /**
 409          * Boolean, controls output of large amounts of debug information.
 410          * @param bool|null $debug
 411          *   - true to enable debugging
 412          *   - false to disable debugging
 413          *   - omitted or null to do nothing
 414          *
 415          * @return bool Previous value of the flag
 416          * @deprecated since 1.28; use setFlag()
 417          */
 418         public function debug( $debug = null ) {
 419                 $res = $this->getFlag( DBO_DEBUG );
 420                 if ( $debug !== null ) {
 421                         $debug ? $this->setFlag( DBO_DEBUG ) : $this->clearFlag( DBO_DEBUG );
 422                 }
 423
 424                 return $res;
 425         }
 426
 427         public function bufferResults( $buffer = null ) {
 428                 $res = !$this->getFlag( DBO_NOBUFFER );
 429                 if ( $buffer !== null ) {
 430                         $buffer ? $this->clearFlag( DBO_NOBUFFER ) : $this->setFlag( DBO_NOBUFFER );
 431                 }
 432
 433                 return $res;
 434         }
 435
 436         /**
 437          * Turns on (false) or off (true) the automatic generation and sending
 438          * of a "we're sorry, but there has been a database error" page on
 439          * database errors. Default is on (false). When turned off, the
 440          * code should use lastErrno() and lastError() to handle the
 441          * situation as appropriate.
 442          *
 443          * Do not use this function outside of the Database classes.
 444          *
 445          * @param null|bool $ignoreErrors
 446          * @return bool The previous value of the flag.
 447          */
 448         protected function ignoreErrors( $ignoreErrors = null ) {
 449                 $res = $this->getFlag( DBO_IGNORE );
 450                 if ( $ignoreErrors !== null ) {
 451                         $ignoreErrors ? $this->setFlag( DBO_IGNORE ) : $this->clearFlag( DBO_IGNORE );
 452                 }
 453
 454                 return $res;
 455         }
 456
 457         public function trxLevel() {
 458                 return $this->mTrxLevel;
 459         }
 460
 461         public function trxTimestamp() {
 462                 return $this->mTrxLevel ? $this->mTrxTimestamp : null;
 463         }
 464
 465         public function tablePrefix( $prefix = null ) {
 466                 $old = $this->mTablePrefix;
 467                 $this->mTablePrefix = $prefix;
 468
 469                 return $old;
 470         }
 471
 472         public function dbSchema( $schema = null ) {
 473                 $old = $this->mSchema;
 474                 $this->mSchema = $schema;
 475
 476                 return $old;
 477         }
 478
 479         /**
 480          * Set the filehandle to copy write statements to.
 481          *
 482          * @param resource $fh File handle
 483          */
 484         public function setFileHandle( $fh ) {
 485                 $this->fileHandle = $fh;
 486         }
 487
 488         public function getLBInfo( $name = null ) {
 489                 if ( is_null( $name ) ) {
 490                         return $this->mLBInfo;
 491                 } else {
 492                         if ( array_key_exists( $name, $this->mLBInfo ) ) {
 493                                 return $this->mLBInfo[$name];
 494                         } else {
 495                                 return null;
 496                         }
 497                 }
 498         }
 499
 500         public function setLBInfo( $name, $value = null ) {
 501                 if ( is_null( $value ) ) {
 502                         $this->mLBInfo = $name;
 503                 } else {
 504                         $this->mLBInfo[$name] = $value;
 505                 }
 506         }
 507
 508         public function setLazyMasterHandle( IDatabase $conn ) {
 509                 $this->lazyMasterHandle = $conn;
 510         }
 511
 512         /**
 513          * @return IDatabase|null
 514          * @see setLazyMasterHandle()
 515          * @since 1.27
 516          */
 517         public function getLazyMasterHandle() {
 518                 return $this->lazyMasterHandle;
 519         }
 520
 521         /**
 522          * @param TransactionProfiler $profiler
 523          * @since 1.27
 524          */
 525         public function setTransactionProfiler( TransactionProfiler $profiler ) {
 526                 $this->trxProfiler = $profiler;
 527         }
 528
 529         /**
 530          * Returns true if this database supports (and uses) cascading deletes
 531          *
 532          * @return bool
 533          */
 534         public function cascadingDeletes() {
 535                 return false;
 536         }
 537
 538         /**
 539          * Returns true if this database supports (and uses) triggers (e.g. on the page table)
 540          *
 541          * @return bool
 542          */
 543         public function cleanupTriggers() {
 544                 return false;
 545         }
 546
 547         /**
 548          * Returns true if this database is strict about what can be put into an IP field.
 549          * Specifically, it uses a NULL value instead of an empty string.
 550          *
 551          * @return bool
 552          */
 553         public function strictIPs() {
 554                 return false;
 555         }
 556
 557         /**
 558          * Returns true if this database uses timestamps rather than integers
 559          *
 560          * @return bool
 561          */
 562         public function realTimestamps() {
 563                 return false;
 564         }
 565
 566         public function implicitGroupby() {
 567                 return true;
 568         }
 569
 570         public function implicitOrderby() {
 571                 return true;
 572         }
 573
 574         /**
 575          * Returns true if this database can do a native search on IP columns
 576          * e.g. this works as expected: .. WHERE rc_ip = '127.42.12.102/32';
 577          *
 578          * @return bool
 579          */
 580         public function searchableIPs() {
 581                 return false;
 582         }
 583
 584         /**
 585          * Returns true if this database can use functional indexes
 586          *
 587          * @return bool
 588          */
 589         public function functionalIndexes() {
 590                 return false;
 591         }
 592
 593         public function lastQuery() {
 594                 return $this->mLastQuery;
 595         }
 596
 597         public function doneWrites() {
 598                 return (bool)$this->mDoneWrites;
 599         }
 600
 601         public function lastDoneWrites() {
 602                 return $this->mDoneWrites ?: false;
 603         }
 604
 605         public function writesPending() {
 606                 return $this->mTrxLevel && $this->mTrxDoneWrites;
 607         }
 608
 609         public function writesOrCallbacksPending() {
 610                 return $this->mTrxLevel && (
 611                         $this->mTrxDoneWrites || $this->mTrxIdleCallbacks || $this->mTrxPreCommitCallbacks
 612                 );
 613         }
 614
 615         public function pendingWriteQueryDuration( $type = self::ESTIMATE_TOTAL ) {
 616                 if ( !$this->mTrxLevel ) {
 617                         return false;
 618                 } elseif ( !$this->mTrxDoneWrites ) {
 619                         return 0.0;
 620                 }
 621
 622                 switch ( $type ) {
 623                         case self::ESTIMATE_DB_APPLY:
 624                                 $this->ping( $rtt );
 625                                 $rttAdjTotal = $this->mTrxWriteAdjQueryCount * $rtt;
 626                                 $applyTime = max( $this->mTrxWriteAdjDuration - $rttAdjTotal, 0 );
 627                                 // For omitted queries, make them count as something at least
 628                                 $omitted = $this->mTrxWriteQueryCount - $this->mTrxWriteAdjQueryCount;
 629                                 $applyTime += self::TINY_WRITE_SEC * $omitted;
 630
 631                                 return $applyTime;
 632                         default: // everything
 633                                 return $this->mTrxWriteDuration;
 634                 }
 635         }
 636
 637         public function pendingWriteCallers() {
 638                 return $this->mTrxLevel ? $this->mTrxWriteCallers : [];
 639         }
 640
 641         public function isOpen() {
 642                 return $this->mOpened;
 643         }
 644
 645         public function setFlag( $flag, $remember = self::REMEMBER_NOTHING ) {
 646                 if ( $remember === self::REMEMBER_PRIOR ) {
 647                         array_push( $this->priorFlags, $this->mFlags );
 648                 }
 649                 $this->mFlags |= $flag;
 650         }
 651
 652         public function clearFlag( $flag, $remember = self::REMEMBER_NOTHING ) {
 653                 if ( $remember === self::REMEMBER_PRIOR ) {
 654                         array_push( $this->priorFlags, $this->mFlags );
 655                 }
 656                 $this->mFlags &= ~$flag;
 657         }
 658
 659         public function restoreFlags( $state = self::RESTORE_PRIOR ) {
 660                 if ( !$this->priorFlags ) {
 661                         return;
 662                 }
 663
 664                 if ( $state === self::RESTORE_INITIAL ) {
 665                         $this->mFlags = reset( $this->priorFlags );
 666                         $this->priorFlags = [];
 667                 } else {
 668                         $this->mFlags = array_pop( $this->priorFlags );
 669                 }
 670         }
 671
 672         public function getFlag( $flag ) {
 673                 return !!( $this->mFlags & $flag );
 674         }
 675
 676         public function getProperty( $name ) {
 677                 return $this->$name;
 678         }
 679
 680         public function getWikiID() {
 681                 if ( $this->mTablePrefix ) {
 682                         return "{$this->mDBname}-{$this->mTablePrefix}";
 683                 } else {
 684                         return $this->mDBname;
 685                 }
 686         }
 687
 688         /**
 689          * Return a path to the DBMS-specific SQL file if it exists,
 690          * otherwise default SQL file
 691          *
 692          * @param string $filename
 693          * @return string
 694          */
 695         private function getSqlFilePath( $filename ) {
 696                 global $IP;
 697                 $dbmsSpecificFilePath = "$IP/maintenance/" . $this->getType() . "/$filename";
 698                 if ( file_exists( $dbmsSpecificFilePath ) ) {
 699                         return $dbmsSpecificFilePath;
 700                 } else {
 701                         return "$IP/maintenance/$filename";
 702                 }
 703         }
 704
 705         /**
 706          * Return a path to the DBMS-specific schema file,
 707          * otherwise default to tables.sql
 708          *
 709          * @return string
 710          */
 711         public function getSchemaPath() {
 712                 return $this->getSqlFilePath( 'tables.sql' );
 713         }
 714
 715         /**
 716          * Return a path to the DBMS-specific update key file,
 717          * otherwise default to update-keys.sql
 718          *
 719          * @return string
 720          */
 721         public function getUpdateKeysPath() {
 722                 return $this->getSqlFilePath( 'update-keys.sql' );
 723         }
 724
 725         /**
 726          * Get information about an index into an object
 727          * @param string $table Table name
 728          * @param string $index Index name
 729          * @param string $fname Calling function name
 730          * @return mixed Database-specific index description class or false if the index does not exist
 731          */
 732         abstract function indexInfo( $table, $index, $fname = __METHOD__ );
 733
 734         /**
 735          * Wrapper for addslashes()
 736          *
 737          * @param string $s String to be slashed.
 738          * @return string Slashed string.
 739          */
 740         abstract function strencode( $s );
 741
 742         /**
 743          * Called by serialize. Throw an exception when DB connection is serialized.
 744          * This causes problems on some database engines because the connection is
 745          * not restored on unserialize.
 746          */
 747         public function __sleep() {
 748                 throw new RuntimeException( 'Database serialization may cause problems, since ' .
 749                         'the connection is not restored on wakeup.' );
 750         }
 751
 752         protected function installErrorHandler() {
 753                 $this->mPHPError = false;
 754                 $this->htmlErrors = ini_set( 'html_errors', '0' );
 755                 set_error_handler( [ $this, 'connectionerrorLogger' ] );
 756         }
 757
 758         /**
 759          * @return bool|string
 760          */
 761         protected function restoreErrorHandler() {
 762                 restore_error_handler();
 763                 if ( $this->htmlErrors !== false ) {
 764                         ini_set( 'html_errors', $this->htmlErrors );
 765                 }
 766                 if ( $this->mPHPError ) {
 767                         $error = preg_replace( '!\[<a.*</a>\]!', '', $this->mPHPError );
 768                         $error = preg_replace( '!^.*?:\s?(.*)$!', '$1', $error );
 769
 770                         return $error;
 771                 } else {
 772                         return false;
 773                 }
 774         }
 775
 776         /**
 777          * @param int $errno
 778          * @param string $errstr
 779          */
 780         public function connectionerrorLogger( $errno, $errstr ) {
 781                 $this->mPHPError = $errstr;
 782         }
 783
 784         /**
 785          * Create a log context to pass to PSR logging functions.
 786          *
 787          * @param array $extras Additional data to add to context
 788          * @return array
 789          */
 790         protected function getLogContext( array $extras = [] ) {
 791                 return array_merge(
 792                         [
 793                                 'db_server' => $this->mServer,
 794                                 'db_name' => $this->mDBname,
 795                                 'db_user' => $this->mUser,
 796                         ],
 797                         $extras
 798                 );
 799         }
 800
 801         public function close() {
 802                 if ( $this->mConn ) {
 803                         if ( $this->trxLevel() ) {
 804                                 $this->commit( __METHOD__, self::FLUSHING_INTERNAL );
 805                         }
 806
 807                         $closed = $this->closeConnection();
 808                         $this->mConn = false;
 809                 } elseif ( $this->mTrxIdleCallbacks || $this->mTrxEndCallbacks ) { // sanity
 810                         throw new RuntimeException( "Transaction callbacks still pending." );
 811                 } else {
 812                         $closed = true;
 813                 }
 814                 $this->mOpened = false;
 815
 816                 return $closed;
 817         }
 818
 819         /**
 820          * Make sure isOpen() returns true as a sanity check
 821          *
 822          * @throws DBUnexpectedError
 823          */
 824         protected function assertOpen() {
 825                 if ( !$this->isOpen() ) {
 826                         throw new DBUnexpectedError( $this, "DB connection was already closed." );
 827                 }
 828         }
 829
 830         /**
 831          * Closes underlying database connection
 832          * @since 1.20
 833          * @return bool Whether connection was closed successfully
 834          */
 835         abstract protected function closeConnection();
 836
 837         function reportConnectionError( $error = 'Unknown error' ) {
 838                 $myError = $this->lastError();
 839                 if ( $myError ) {
 840                         $error = $myError;
 841                 }
 842
 843                 # New method
 844                 throw new DBConnectionError( $this, $error );
 845         }
 846
 847         /**
 848          * The DBMS-dependent part of query()
 849          *
 850          * @param string $sql SQL query.
 851          * @return ResultWrapper|bool Result object to feed to fetchObject,
 852          *   fetchRow, ...; or false on failure
 853          */
 854         abstract protected function doQuery( $sql );
 855
 856         /**
 857          * Determine whether a query writes to the DB.
 858          * Should return true if unsure.
 859          *
 860          * @param string $sql
 861          * @return bool
 862          */
 863         protected function isWriteQuery( $sql ) {
 864                 return !preg_match(
 865                         '/^(?:SELECT|BEGIN|ROLLBACK|COMMIT|SET|SHOW|EXPLAIN|\(SELECT)\b/i', $sql );
 866         }
 867
 868         /**
 869          * @param $sql
 870          * @return string|null
 871          */
 872         protected function getQueryVerb( $sql ) {
 873                 return preg_match( '/^\s*([a-z]+)/i', $sql, $m ) ? strtoupper( $m[1] ) : null;
 874         }
 875
 876         /**
 877          * Determine whether a SQL statement is sensitive to isolation level.
 878          * A SQL statement is considered transactable if its result could vary
 879          * depending on the transaction isolation level. Operational commands
 880          * such as 'SET' and 'SHOW' are not considered to be transactable.
 881          *
 882          * @param string $sql
 883          * @return bool
 884          */
 885         protected function isTransactableQuery( $sql ) {
 886                 $verb = $this->getQueryVerb( $sql );
 887                 return !in_array( $verb, [ 'BEGIN', 'COMMIT', 'ROLLBACK', 'SHOW', 'SET' ], true );
 888         }
 889
 890         public function query( $sql, $fname = __METHOD__, $tempIgnore = false ) {
 891                 global $wgUser;
 892
 893                 $priorWritesPending = $this->writesOrCallbacksPending();
 894                 $this->mLastQuery = $sql;
 895
 896                 $isWrite = $this->isWriteQuery( $sql );
 897                 if ( $isWrite ) {
 898                         $reason = $this->getReadOnlyReason();
 899                         if ( $reason !== false ) {
 900                                 throw new DBReadOnlyError( $this, "Database is read-only: $reason" );
 901                         }
 902                         # Set a flag indicating that writes have been done
 903                         $this->mDoneWrites = microtime( true );
 904                 }
 905
 906                 # Add a comment for easy SHOW PROCESSLIST interpretation
 907                 if ( is_object( $wgUser ) && $wgUser->isItemLoaded( 'name' ) ) {
 908                         $userName = $wgUser->getName();
 909                         if ( mb_strlen( $userName ) > 15 ) {
 910                                 $userName = mb_substr( $userName, 0, 15 ) . '...';
 911                         }
 912                         $userName = str_replace( '/', '', $userName );
 913                 } else {
 914                         $userName = '';
 915                 }
 916
 917                 // Add trace comment to the begin of the sql string, right after the operator.
 918                 // Or, for one-word queries (like "BEGIN" or COMMIT") add it to the end (bug 42598)
 919                 $commentedSql = preg_replace( '/\s|$/', " /* $fname $userName */ ", $sql, 1 );
 920
 921                 # Start implicit transactions that wrap the request if DBO_TRX is enabled
 922                 if ( !$this->mTrxLevel && $this->getFlag( DBO_TRX )
 923                         && $this->isTransactableQuery( $sql )
 924                 ) {
 925                         $this->begin( __METHOD__ . " ($fname)", self::TRANSACTION_INTERNAL );
 926                         $this->mTrxAutomatic = true;
 927                 }
 928
 929                 # Keep track of whether the transaction has write queries pending
 930                 if ( $this->mTrxLevel && !$this->mTrxDoneWrites && $isWrite ) {
 931                         $this->mTrxDoneWrites = true;
 932                         $this->trxProfiler->transactionWritingIn(
 933                                 $this->mServer, $this->mDBname, $this->mTrxShortId );
 934                 }
 935
 936                 if ( $this->debug() ) {
 937                         $this->queryLogger->debug( "{$this->mDBname} {$commentedSql}" );
 938                 }
 939
 940                 # Avoid fatals if close() was called
 941                 $this->assertOpen();
 942
 943                 # Send the query to the server
 944                 $ret = $this->doProfiledQuery( $sql, $commentedSql, $isWrite, $fname );
 945
 946                 # Try reconnecting if the connection was lost
 947                 if ( false === $ret && $this->wasErrorReissuable() ) {
 948                         $recoverable = $this->canRecoverFromDisconnect( $sql, $priorWritesPending );
 949                         # Stash the last error values before anything might clear them
 950                         $lastError = $this->lastError();
 951                         $lastErrno = $this->lastErrno();
 952                         # Update state tracking to reflect transaction loss due to disconnection
 953                         $this->handleTransactionLoss();
 954                         if ( $this->reconnect() ) {
 955                                 $msg = __METHOD__ . ": lost connection to {$this->getServer()}; reconnected";
 956                                 $this->connLogger->warning( $msg );
 957                                 $this->queryLogger->warning(
 958                                         "$msg:\n" . ( new RuntimeException() )->getTraceAsString() );
 959
 960                                 if ( !$recoverable ) {
 961                                         # Callers may catch the exception and continue to use the DB
 962                                         $this->reportQueryError( $lastError, $lastErrno, $sql, $fname );
 963                                 } else {
 964                                         # Should be safe to silently retry the query
 965                                         $ret = $this->doProfiledQuery( $sql, $commentedSql, $isWrite, $fname );
 966                                 }
 967                         } else {
 968                                 $msg = __METHOD__ . ": lost connection to {$this->getServer()} permanently";
 969                                 $this->connLogger->error( $msg );
 970                         }
 971                 }
 972
 973                 if ( false === $ret ) {
 974                         # Deadlocks cause the entire transaction to abort, not just the statement.
 975                         # http://dev.mysql.com/doc/refman/5.7/en/innodb-error-handling.html
 976                         # https://www.postgresql.org/docs/9.1/static/explicit-locking.html
 977                         if ( $this->wasDeadlock() ) {
 978                                 if ( $this->explicitTrxActive() || $priorWritesPending ) {
 979                                         $tempIgnore = false; // not recoverable
 980                                 }
 981                                 # Update state tracking to reflect transaction loss
 982                                 $this->handleTransactionLoss();
 983                         }
 984
 985                         $this->reportQueryError(
 986                                 $this->lastError(), $this->lastErrno(), $sql, $fname, $tempIgnore );
 987                 }
 988
 989                 $res = $this->resultObject( $ret );
 990
 991                 return $res;
 992         }
 993
 994         private function doProfiledQuery( $sql, $commentedSql, $isWrite, $fname ) {
 995                 $isMaster = !is_null( $this->getLBInfo( 'master' ) );
 996                 # generalizeSQL() will probably cut down the query to reasonable
 997                 # logging size most of the time. The substr is really just a sanity check.
 998                 if ( $isMaster ) {
 999                         $queryProf = 'query-m: ' . substr( self::generalizeSQL( $sql ), 0, 255 );
1000                 } else {
1001                         $queryProf = 'query: ' . substr( self::generalizeSQL( $sql ), 0, 255 );
1002                 }
1003
1004                 # Include query transaction state
1005                 $queryProf .= $this->mTrxShortId ? " [TRX#{$this->mTrxShortId}]" : "";
1006
1007                 $startTime = microtime( true );
1008                 $this->profiler->profileIn( $queryProf );
1009                 $ret = $this->doQuery( $commentedSql );
1010                 $this->profiler->profileOut( $queryProf );
1011                 $queryRuntime = max( microtime( true ) - $startTime, 0.0 );
1012
1013                 unset( $queryProfSection ); // profile out (if set)
1014
1015                 if ( $ret !== false ) {
1016                         $this->lastPing = $startTime;
1017                         if ( $isWrite && $this->mTrxLevel ) {
1018                                 $this->updateTrxWriteQueryTime( $sql, $queryRuntime );
1019                                 $this->mTrxWriteCallers[] = $fname;
1020                         }
1021                 }
1022
1023                 if ( $sql === self::PING_QUERY ) {
1024                         $this->mRTTEstimate = $queryRuntime;
1025                 }
1026
1027                 $this->trxProfiler->recordQueryCompletion(
1028                         $queryProf, $startTime, $isWrite, $this->affectedRows()
1029                 );
1030                 MWDebug::query( $sql, $fname, $isMaster, $queryRuntime );
1031
1032                 return $ret;
1033         }
1034
1035         /**
1036          * Update the estimated run-time of a query, not counting large row lock times
1037          *
1038          * LoadBalancer can be set to rollback transactions that will create huge replication
1039          * lag. It bases this estimate off of pendingWriteQueryDuration(). Certain simple
1040          * queries, like inserting a row can take a long time due to row locking. This method
1041          * uses some simple heuristics to discount those cases.
1042          *
1043          * @param string $sql A SQL write query
1044          * @param float $runtime Total runtime, including RTT
1045          */
1046         private function updateTrxWriteQueryTime( $sql, $runtime ) {
1047                 // Whether this is indicative of replica DB runtime (except for RBR or ws_repl)
1048                 $indicativeOfReplicaRuntime = true;
1049                 if ( $runtime > self::SLOW_WRITE_SEC ) {
1050                         $verb = $this->getQueryVerb( $sql );
1051                         // insert(), upsert(), replace() are fast unless bulky in size or blocked on locks
1052                         if ( $verb === 'INSERT' ) {
1053                                 $indicativeOfReplicaRuntime = $this->affectedRows() > self::SMALL_WRITE_ROWS;
1054                         } elseif ( $verb === 'REPLACE' ) {
1055                                 $indicativeOfReplicaRuntime = $this->affectedRows() > self::SMALL_WRITE_ROWS / 2;
1056                         }
1057                 }
1058
1059                 $this->mTrxWriteDuration += $runtime;
1060                 $this->mTrxWriteQueryCount += 1;
1061                 if ( $indicativeOfReplicaRuntime ) {
1062                         $this->mTrxWriteAdjDuration += $runtime;
1063                         $this->mTrxWriteAdjQueryCount += 1;
1064                 }
1065         }
1066
1067         private function canRecoverFromDisconnect( $sql, $priorWritesPending ) {
1068                 # Transaction dropped; this can mean lost writes, or REPEATABLE-READ snapshots.
1069                 # Dropped connections also mean that named locks are automatically released.
1070                 # Only allow error suppression in autocommit mode or when the lost transaction
1071                 # didn't matter anyway (aside from DBO_TRX snapshot loss).
1072                 if ( $this->mNamedLocksHeld ) {
1073                         return false; // possible critical section violation
1074                 } elseif ( $sql === 'COMMIT' ) {
1075                         return !$priorWritesPending; // nothing written anyway? (T127428)
1076                 } elseif ( $sql === 'ROLLBACK' ) {
1077                         return true; // transaction lost...which is also what was requested :)
1078                 } elseif ( $this->explicitTrxActive() ) {
1079                         return false; // don't drop atomocity
1080                 } elseif ( $priorWritesPending ) {
1081                         return false; // prior writes lost from implicit transaction
1082                 }
1083
1084                 return true;
1085         }
1086
1087         private function handleTransactionLoss() {
1088                 $this->mTrxLevel = 0;
1089                 $this->mTrxIdleCallbacks = []; // bug 65263
1090                 $this->mTrxPreCommitCallbacks = []; // bug 65263
1091                 try {
1092                         // Handle callbacks in mTrxEndCallbacks
1093                         $this->runOnTransactionIdleCallbacks( self::TRIGGER_ROLLBACK );
1094                         $this->runTransactionListenerCallbacks( self::TRIGGER_ROLLBACK );
1095                         return null;
1096                 } catch ( Exception $e ) {
1097                         // Already logged; move on...
1098                         return $e;
1099                 }
1100         }
1101
1102         public function reportQueryError( $error, $errno, $sql, $fname, $tempIgnore = false ) {
1103                 if ( $this->ignoreErrors() || $tempIgnore ) {
1104                         $this->queryLogger->debug( "SQL ERROR (ignored): $error\n" );
1105                 } else {
1106                         $sql1line = mb_substr( str_replace( "\n", "\\n", $sql ), 0, 5 * 1024 );
1107                         $this->queryLogger->error(
1108                                 "{fname}\t{db_server}\t{errno}\t{error}\t{sql1line}",
1109                                 $this->getLogContext( [
1110                                         'method' => __METHOD__,
1111                                         'errno' => $errno,
1112                                         'error' => $error,
1113                                         'sql1line' => $sql1line,
1114                                         'fname' => $fname,
1115                                 ] )
1116                         );
1117                         $this->queryLogger->debug( "SQL ERROR: " . $error . "\n" );
1118                         throw new DBQueryError( $this, $error, $errno, $sql, $fname );
1119                 }
1120         }
1121
1122         /**
1123          * Intended to be compatible with the PEAR::DB wrapper functions.
1124          * http://pear.php.net/manual/en/package.database.db.intro-execute.php
1125          *
1126          * ? = scalar value, quoted as necessary
1127          * ! = raw SQL bit (a function for instance)
1128          * & = filename; reads the file and inserts as a blob
1129          *     (we don't use this though...)
1130          *
1131          * @param string $sql
1132          * @param string $func
1133          *
1134          * @return array
1135          */
1136         protected function prepare( $sql, $func = __METHOD__ ) {
1137                 /* MySQL doesn't support prepared statements (yet), so just
1138                  * pack up the query for reference. We'll manually replace
1139                  * the bits later.
1140                  */
1141                 return [ 'query' => $sql, 'func' => $func ];
1142         }
1143
1144         /**
1145          * Free a prepared query, generated by prepare().
1146          * @param string $prepared
1147          */
1148         protected function freePrepared( $prepared ) {
1149                 /* No-op by default */
1150         }
1151
1152         /**
1153          * Execute a prepared query with the various arguments
1154          * @param string $prepared The prepared sql
1155          * @param mixed $args Either an array here, or put scalars as varargs
1156          *
1157          * @return ResultWrapper
1158          */
1159         public function execute( $prepared, $args = null ) {
1160                 if ( !is_array( $args ) ) {
1161                         # Pull the var args
1162                         $args = func_get_args();
1163                         array_shift( $args );
1164                 }
1165
1166                 $sql = $this->fillPrepared( $prepared['query'], $args );
1167
1168                 return $this->query( $sql, $prepared['func'] );
1169         }
1170
1171         /**
1172          * For faking prepared SQL statements on DBs that don't support it directly.
1173          *
1174          * @param string $preparedQuery A 'preparable' SQL statement
1175          * @param array $args Array of Arguments to fill it with
1176          * @return string Executable SQL
1177          */
1178         public function fillPrepared( $preparedQuery, $args ) {
1179                 reset( $args );
1180                 $this->preparedArgs =& $args;
1181
1182                 return preg_replace_callback( '/(\\\\[?!&]|[?!&])/',
1183                         [ &$this, 'fillPreparedArg' ], $preparedQuery );
1184         }
1185
1186         /**
1187          * preg_callback func for fillPrepared()
1188          * The arguments should be in $this->preparedArgs and must not be touched
1189          * while we're doing this.
1190          *
1191          * @param array $matches
1192          * @throws DBUnexpectedError
1193          * @return string
1194          */
1195         protected function fillPreparedArg( $matches ) {
1196                 switch ( $matches[1] ) {
1197                         case '\\?':
1198                                 return '?';
1199                         case '\\!':
1200                                 return '!';
1201                         case '\\&':
1202                                 return '&';
1203                 }
1204
1205                 list( /* $n */, $arg ) = each( $this->preparedArgs );
1206
1207                 switch ( $matches[1] ) {
1208                         case '?':
1209                                 return $this->addQuotes( $arg );
1210                         case '!':
1211                                 return $arg;
1212                         case '&':
1213                                 # return $this->addQuotes( file_get_contents( $arg ) );
1214                                 throw new DBUnexpectedError(
1215                                         $this,
1216                                         '& mode is not implemented. If it\'s really needed, uncomment the line above.'
1217                                 );
1218                         default:
1219                                 throw new DBUnexpectedError(
1220                                         $this,
1221                                         'Received invalid match. This should never happen!'
1222                                 );
1223                 }
1224         }
1225
1226         public function freeResult( $res ) {
1227         }
1228
1229         public function selectField(
1230                 $table, $var, $cond = '', $fname = __METHOD__, $options = []
1231         ) {
1232                 if ( $var === '*' ) { // sanity
1233                         throw new DBUnexpectedError( $this, "Cannot use a * field: got '$var'" );
1234                 }
1235
1236                 if ( !is_array( $options ) ) {
1237                         $options = [ $options ];
1238                 }
1239
1240                 $options['LIMIT'] = 1;
1241
1242                 $res = $this->select( $table, $var, $cond, $fname, $options );
1243                 if ( $res === false || !$this->numRows( $res ) ) {
1244                         return false;
1245                 }
1246
1247                 $row = $this->fetchRow( $res );
1248
1249                 if ( $row !== false ) {
1250                         return reset( $row );
1251                 } else {
1252                         return false;
1253                 }
1254         }
1255
1256         public function selectFieldValues(
1257                 $table, $var, $cond = '', $fname = __METHOD__, $options = [], $join_conds = []
1258         ) {
1259                 if ( $var === '*' ) { // sanity
1260                         throw new DBUnexpectedError( $this, "Cannot use a * field" );
1261                 } elseif ( !is_string( $var ) ) { // sanity
1262                         throw new DBUnexpectedError( $this, "Cannot use an array of fields" );
1263                 }
1264
1265                 if ( !is_array( $options ) ) {
1266                         $options = [ $options ];
1267                 }
1268
1269                 $res = $this->select( $table, $var, $cond, $fname, $options, $join_conds );
1270                 if ( $res === false ) {
1271                         return false;
1272                 }
1273
1274                 $values = [];
1275                 foreach ( $res as $row ) {
1276                         $values[] = $row->$var;
1277                 }
1278
1279                 return $values;
1280         }
1281
1282         /**
1283          * Returns an optional USE INDEX clause to go after the table, and a
1284          * string to go at the end of the query.
1285          *
1286          * @param array $options Associative array of options to be turned into
1287          *   an SQL query, valid keys are listed in the function.
1288          * @return array
1289          * @see DatabaseBase::select()
1290          */
1291         public function makeSelectOptions( $options ) {
1292                 $preLimitTail = $postLimitTail = '';
1293                 $startOpts = '';
1294
1295                 $noKeyOptions = [];
1296
1297                 foreach ( $options as $key => $option ) {
1298                         if ( is_numeric( $key ) ) {
1299                                 $noKeyOptions[$option] = true;
1300                         }
1301                 }
1302
1303                 $preLimitTail .= $this->makeGroupByWithHaving( $options );
1304
1305                 $preLimitTail .= $this->makeOrderBy( $options );
1306
1307                 // if (isset($options['LIMIT'])) {
1308                 //      $tailOpts .= $this->limitResult('', $options['LIMIT'],
1309                 //              isset($options['OFFSET']) ? $options['OFFSET']
1310                 //              : false);
1311                 // }
1312
1313                 if ( isset( $noKeyOptions['FOR UPDATE'] ) ) {
1314                         $postLimitTail .= ' FOR UPDATE';
1315                 }
1316
1317                 if ( isset( $noKeyOptions['LOCK IN SHARE MODE'] ) ) {
1318                         $postLimitTail .= ' LOCK IN SHARE MODE';
1319                 }
1320
1321                 if ( isset( $noKeyOptions['DISTINCT'] ) || isset( $noKeyOptions['DISTINCTROW'] ) ) {
1322                         $startOpts .= 'DISTINCT';
1323                 }
1324
1325                 # Various MySQL extensions
1326                 if ( isset( $noKeyOptions['STRAIGHT_JOIN'] ) ) {
1327                         $startOpts .= ' /*! STRAIGHT_JOIN */';
1328                 }
1329
1330                 if ( isset( $noKeyOptions['HIGH_PRIORITY'] ) ) {
1331                         $startOpts .= ' HIGH_PRIORITY';
1332                 }
1333
1334                 if ( isset( $noKeyOptions['SQL_BIG_RESULT'] ) ) {
1335                         $startOpts .= ' SQL_BIG_RESULT';
1336                 }
1337
1338                 if ( isset( $noKeyOptions['SQL_BUFFER_RESULT'] ) ) {
1339                         $startOpts .= ' SQL_BUFFER_RESULT';
1340                 }
1341
1342                 if ( isset( $noKeyOptions['SQL_SMALL_RESULT'] ) ) {
1343                         $startOpts .= ' SQL_SMALL_RESULT';
1344                 }
1345
1346                 if ( isset( $noKeyOptions['SQL_CALC_FOUND_ROWS'] ) ) {
1347                         $startOpts .= ' SQL_CALC_FOUND_ROWS';
1348                 }
1349
1350                 if ( isset( $noKeyOptions['SQL_CACHE'] ) ) {
1351                         $startOpts .= ' SQL_CACHE';
1352                 }
1353
1354                 if ( isset( $noKeyOptions['SQL_NO_CACHE'] ) ) {
1355                         $startOpts .= ' SQL_NO_CACHE';
1356                 }
1357
1358                 if ( isset( $options['USE INDEX'] ) && is_string( $options['USE INDEX'] ) ) {
1359                         $useIndex = $this->useIndexClause( $options['USE INDEX'] );
1360                 } else {
1361                         $useIndex = '';
1362                 }
1363                 if ( isset( $options['IGNORE INDEX'] ) && is_string( $options['IGNORE INDEX'] ) ) {
1364                         $ignoreIndex = $this->ignoreIndexClause( $options['IGNORE INDEX'] );
1365                 } else {
1366                         $ignoreIndex = '';
1367                 }
1368
1369                 return [ $startOpts, $useIndex, $preLimitTail, $postLimitTail, $ignoreIndex ];
1370         }
1371
1372         /**
1373          * Returns an optional GROUP BY with an optional HAVING
1374          *
1375          * @param array $options Associative array of options
1376          * @return string
1377          * @see DatabaseBase::select()
1378          * @since 1.21
1379          */
1380         public function makeGroupByWithHaving( $options ) {
1381                 $sql = '';
1382                 if ( isset( $options['GROUP BY'] ) ) {
1383                         $gb = is_array( $options['GROUP BY'] )
1384                                 ? implode( ',', $options['GROUP BY'] )
1385                                 : $options['GROUP BY'];
1386                         $sql .= ' GROUP BY ' . $gb;
1387                 }
1388                 if ( isset( $options['HAVING'] ) ) {
1389                         $having = is_array( $options['HAVING'] )
1390                                 ? $this->makeList( $options['HAVING'], LIST_AND )
1391                                 : $options['HAVING'];
1392                         $sql .= ' HAVING ' . $having;
1393                 }
1394
1395                 return $sql;
1396         }
1397
1398         /**
1399          * Returns an optional ORDER BY
1400          *
1401          * @param array $options Associative array of options
1402          * @return string
1403          * @see DatabaseBase::select()
1404          * @since 1.21
1405          */
1406         public function makeOrderBy( $options ) {
1407                 if ( isset( $options['ORDER BY'] ) ) {
1408                         $ob = is_array( $options['ORDER BY'] )
1409                                 ? implode( ',', $options['ORDER BY'] )
1410                                 : $options['ORDER BY'];
1411
1412                         return ' ORDER BY ' . $ob;
1413                 }
1414
1415                 return '';
1416         }
1417
1418         // See IDatabase::select for the docs for this function
1419         public function select( $table, $vars, $conds = '', $fname = __METHOD__,
1420                 $options = [], $join_conds = [] ) {
1421                 $sql = $this->selectSQLText( $table, $vars, $conds, $fname, $options, $join_conds );
1422
1423                 return $this->query( $sql, $fname );
1424         }
1425
1426         public function selectSQLText( $table, $vars, $conds = '', $fname = __METHOD__,
1427                 $options = [], $join_conds = []
1428         ) {
1429                 if ( is_array( $vars ) ) {
1430                         $vars = implode( ',', $this->fieldNamesWithAlias( $vars ) );
1431                 }
1432
1433                 $options = (array)$options;
1434                 $useIndexes = ( isset( $options['USE INDEX'] ) && is_array( $options['USE INDEX'] ) )
1435                         ? $options['USE INDEX']
1436                         : [];
1437                 $ignoreIndexes = ( isset( $options['IGNORE INDEX'] ) && is_array( $options['IGNORE INDEX'] ) )
1438                         ? $options['IGNORE INDEX']
1439                         : [];
1440
1441                 if ( is_array( $table ) ) {
1442                         $from = ' FROM ' .
1443                                 $this->tableNamesWithIndexClauseOrJOIN( $table, $useIndexes, $ignoreIndexes, $join_conds );
1444                 } elseif ( $table != '' ) {
1445                         if ( $table[0] == ' ' ) {
1446                                 $from = ' FROM ' . $table;
1447                         } else {
1448                                 $from = ' FROM ' .
1449                                         $this->tableNamesWithIndexClauseOrJOIN( [ $table ], $useIndexes, $ignoreIndexes, [] );
1450                         }
1451                 } else {
1452                         $from = '';
1453                 }
1454
1455                 list( $startOpts, $useIndex, $preLimitTail, $postLimitTail, $ignoreIndex ) =
1456                         $this->makeSelectOptions( $options );
1457
1458                 if ( !empty( $conds ) ) {
1459                         if ( is_array( $conds ) ) {
1460                                 $conds = $this->makeList( $conds, LIST_AND );
1461                         }
1462                         $sql = "SELECT $startOpts $vars $from $useIndex $ignoreIndex WHERE $conds $preLimitTail";
1463                 } else {
1464                         $sql = "SELECT $startOpts $vars $from $useIndex $ignoreIndex $preLimitTail";
1465                 }
1466
1467                 if ( isset( $options['LIMIT'] ) ) {
1468                         $sql = $this->limitResult( $sql, $options['LIMIT'],
1469                                 isset( $options['OFFSET'] ) ? $options['OFFSET'] : false );
1470                 }
1471                 $sql = "$sql $postLimitTail";
1472
1473                 if ( isset( $options['EXPLAIN'] ) ) {
1474                         $sql = 'EXPLAIN ' . $sql;
1475                 }
1476
1477                 return $sql;
1478         }
1479
1480         public function selectRow( $table, $vars, $conds, $fname = __METHOD__,
1481                 $options = [], $join_conds = []
1482         ) {
1483                 $options = (array)$options;
1484                 $options['LIMIT'] = 1;
1485                 $res = $this->select( $table, $vars, $conds, $fname, $options, $join_conds );
1486
1487                 if ( $res === false ) {
1488                         return false;
1489                 }
1490
1491                 if ( !$this->numRows( $res ) ) {
1492                         return false;
1493                 }
1494
1495                 $obj = $this->fetchObject( $res );
1496
1497                 return $obj;
1498         }
1499
1500         public function estimateRowCount(
1501                 $table, $vars = '*', $conds = '', $fname = __METHOD__, $options = []
1502         ) {
1503                 $rows = 0;
1504                 $res = $this->select( $table, [ 'rowcount' => 'COUNT(*)' ], $conds, $fname, $options );
1505
1506                 if ( $res ) {
1507                         $row = $this->fetchRow( $res );
1508                         $rows = ( isset( $row['rowcount'] ) ) ? (int)$row['rowcount'] : 0;
1509                 }
1510
1511                 return $rows;
1512         }
1513
1514         public function selectRowCount(
1515                 $tables, $vars = '*', $conds = '', $fname = __METHOD__, $options = [], $join_conds = []
1516         ) {
1517                 $rows = 0;
1518                 $sql = $this->selectSQLText( $tables, '1', $conds, $fname, $options, $join_conds );
1519                 $res = $this->query( "SELECT COUNT(*) AS rowcount FROM ($sql) tmp_count", $fname );
1520
1521                 if ( $res ) {
1522                         $row = $this->fetchRow( $res );
1523                         $rows = ( isset( $row['rowcount'] ) ) ? (int)$row['rowcount'] : 0;
1524                 }
1525
1526                 return $rows;
1527         }
1528
1529         /**
1530          * Removes most variables from an SQL query and replaces them with X or N for numbers.
1531          * It's only slightly flawed. Don't use for anything important.
1532          *
1533          * @param string $sql A SQL Query
1534          *
1535          * @return string
1536          */
1537         protected static function generalizeSQL( $sql ) {
1538                 # This does the same as the regexp below would do, but in such a way
1539                 # as to avoid crashing php on some large strings.
1540                 # $sql = preg_replace( "/'([^\\\\']|\\\\.)*'|\"([^\\\\\"]|\\\\.)*\"/", "'X'", $sql );
1541
1542                 $sql = str_replace( "\\\\", '', $sql );
1543                 $sql = str_replace( "\\'", '', $sql );
1544                 $sql = str_replace( "\\\"", '', $sql );
1545                 $sql = preg_replace( "/'.*'/s", "'X'", $sql );
1546                 $sql = preg_replace( '/".*"/s', "'X'", $sql );
1547
1548                 # All newlines, tabs, etc replaced by single space
1549                 $sql = preg_replace( '/\s+/', ' ', $sql );
1550
1551                 # All numbers => N,
1552                 # except the ones surrounded by characters, e.g. l10n
1553                 $sql = preg_replace( '/-?\d+(,-?\d+)+/s', 'N,...,N', $sql );
1554                 $sql = preg_replace( '/(?<![a-zA-Z])-?\d+(?![a-zA-Z])/s', 'N', $sql );
1555
1556                 return $sql;
1557         }
1558
1559         public function fieldExists( $table, $field, $fname = __METHOD__ ) {
1560                 $info = $this->fieldInfo( $table, $field );
1561
1562                 return (bool)$info;
1563         }
1564
1565         public function indexExists( $table, $index, $fname = __METHOD__ ) {
1566                 if ( !$this->tableExists( $table ) ) {
1567                         return null;
1568                 }
1569
1570                 $info = $this->indexInfo( $table, $index, $fname );
1571                 if ( is_null( $info ) ) {
1572                         return null;
1573                 } else {
1574                         return $info !== false;
1575                 }
1576         }
1577
1578         public function tableExists( $table, $fname = __METHOD__ ) {
1579                 $table = $this->tableName( $table );
1580                 $old = $this->ignoreErrors( true );
1581                 $res = $this->query( "SELECT 1 FROM $table LIMIT 1", $fname );
1582                 $this->ignoreErrors( $old );
1583
1584                 return (bool)$res;
1585         }
1586
1587         public function indexUnique( $table, $index ) {
1588                 $indexInfo = $this->indexInfo( $table, $index );
1589
1590                 if ( !$indexInfo ) {
1591                         return null;
1592                 }
1593
1594                 return !$indexInfo[0]->Non_unique;
1595         }
1596
1597         /**
1598          * Helper for DatabaseBase::insert().
1599          *
1600          * @param array $options
1601          * @return string
1602          */
1603         protected function makeInsertOptions( $options ) {
1604                 return implode( ' ', $options );
1605         }
1606
1607         public function insert( $table, $a, $fname = __METHOD__, $options = [] ) {
1608                 # No rows to insert, easy just return now
1609                 if ( !count( $a ) ) {
1610                         return true;
1611                 }
1612
1613                 $table = $this->tableName( $table );
1614
1615                 if ( !is_array( $options ) ) {
1616                         $options = [ $options ];
1617                 }
1618
1619                 $fh = null;
1620                 if ( isset( $options['fileHandle'] ) ) {
1621                         $fh = $options['fileHandle'];
1622                 }
1623                 $options = $this->makeInsertOptions( $options );
1624
1625                 if ( isset( $a[0] ) && is_array( $a[0] ) ) {
1626                         $multi = true;
1627                         $keys = array_keys( $a[0] );
1628                 } else {
1629                         $multi = false;
1630                         $keys = array_keys( $a );
1631                 }
1632
1633                 $sql = 'INSERT ' . $options .
1634                         " INTO $table (" . implode( ',', $keys ) . ') VALUES ';
1635
1636                 if ( $multi ) {
1637                         $first = true;
1638                         foreach ( $a as $row ) {
1639                                 if ( $first ) {
1640                                         $first = false;
1641                                 } else {
1642                                         $sql .= ',';
1643                                 }
1644                                 $sql .= '(' . $this->makeList( $row ) . ')';
1645                         }
1646                 } else {
1647                         $sql .= '(' . $this->makeList( $a ) . ')';
1648                 }
1649
1650                 if ( $fh !== null && false === fwrite( $fh, $sql ) ) {
1651                         return false;
1652                 } elseif ( $fh !== null ) {
1653                         return true;
1654                 }
1655
1656                 return (bool)$this->query( $sql, $fname );
1657         }
1658
1659         /**
1660          * Make UPDATE options array for DatabaseBase::makeUpdateOptions
1661          *
1662          * @param array $options
1663          * @return array
1664          */
1665         protected function makeUpdateOptionsArray( $options ) {
1666                 if ( !is_array( $options ) ) {
1667                         $options = [ $options ];
1668                 }
1669
1670                 $opts = [];
1671
1672                 if ( in_array( 'LOW_PRIORITY', $options ) ) {
1673                         $opts[] = $this->lowPriorityOption();
1674                 }
1675
1676                 if ( in_array( 'IGNORE', $options ) ) {
1677                         $opts[] = 'IGNORE';
1678                 }
1679
1680                 return $opts;
1681         }
1682
1683         /**
1684          * Make UPDATE options for the DatabaseBase::update function
1685          *
1686          * @param array $options The options passed to DatabaseBase::update
1687          * @return string
1688          */
1689         protected function makeUpdateOptions( $options ) {
1690                 $opts = $this->makeUpdateOptionsArray( $options );
1691
1692                 return implode( ' ', $opts );
1693         }
1694
1695         function update( $table, $values, $conds, $fname = __METHOD__, $options = [] ) {
1696                 $table = $this->tableName( $table );
1697                 $opts = $this->makeUpdateOptions( $options );
1698                 $sql = "UPDATE $opts $table SET " . $this->makeList( $values, LIST_SET );
1699
1700                 if ( $conds !== [] && $conds !== '*' ) {
1701                         $sql .= " WHERE " . $this->makeList( $conds, LIST_AND );
1702                 }
1703
1704                 return $this->query( $sql, $fname );
1705         }
1706
1707         public function makeList( $a, $mode = LIST_COMMA ) {
1708                 if ( !is_array( $a ) ) {
1709                         throw new DBUnexpectedError( $this, __METHOD__ . ' called with incorrect parameters' );
1710                 }
1711
1712                 $first = true;
1713                 $list = '';
1714
1715                 foreach ( $a as $field => $value ) {
1716                         if ( !$first ) {
1717                                 if ( $mode == LIST_AND ) {
1718                                         $list .= ' AND ';
1719                                 } elseif ( $mode == LIST_OR ) {
1720                                         $list .= ' OR ';
1721                                 } else {
1722                                         $list .= ',';
1723                                 }
1724                         } else {
1725                                 $first = false;
1726                         }
1727
1728                         if ( ( $mode == LIST_AND || $mode == LIST_OR ) && is_numeric( $field ) ) {
1729                                 $list .= "($value)";
1730                         } elseif ( ( $mode == LIST_SET ) && is_numeric( $field ) ) {
1731                                 $list .= "$value";
1732                         } elseif ( ( $mode == LIST_AND || $mode == LIST_OR ) && is_array( $value ) ) {
1733                                 // Remove null from array to be handled separately if found
1734                                 $includeNull = false;
1735                                 foreach ( array_keys( $value, null, true ) as $nullKey ) {
1736                                         $includeNull = true;
1737                                         unset( $value[$nullKey] );
1738                                 }
1739                                 if ( count( $value ) == 0 && !$includeNull ) {
1740                                         throw new InvalidArgumentException( __METHOD__ . ": empty input for field $field" );
1741                                 } elseif ( count( $value ) == 0 ) {
1742                                         // only check if $field is null
1743                                         $list .= "$field IS NULL";
1744                                 } else {
1745                                         // IN clause contains at least one valid element
1746                                         if ( $includeNull ) {
1747                                                 // Group subconditions to ensure correct precedence
1748                                                 $list .= '(';
1749                                         }
1750                                         if ( count( $value ) == 1 ) {
1751                                                 // Special-case single values, as IN isn't terribly efficient
1752                                                 // Don't necessarily assume the single key is 0; we don't
1753                                                 // enforce linear numeric ordering on other arrays here.
1754                                                 $value = array_values( $value )[0];
1755                                                 $list .= $field . " = " . $this->addQuotes( $value );
1756                                         } else {
1757                                                 $list .= $field . " IN (" . $this->makeList( $value ) . ") ";
1758                                         }
1759                                         // if null present in array, append IS NULL
1760                                         if ( $includeNull ) {
1761                                                 $list .= " OR $field IS NULL)";
1762                                         }
1763                                 }
1764                         } elseif ( $value === null ) {
1765                                 if ( $mode == LIST_AND || $mode == LIST_OR ) {
1766                                         $list .= "$field IS ";
1767                                 } elseif ( $mode == LIST_SET ) {
1768                                         $list .= "$field = ";
1769                                 }
1770                                 $list .= 'NULL';
1771                         } else {
1772                                 if ( $mode == LIST_AND || $mode == LIST_OR || $mode == LIST_SET ) {
1773                                         $list .= "$field = ";
1774                                 }
1775                                 $list .= $mode == LIST_NAMES ? $value : $this->addQuotes( $value );
1776                         }
1777                 }
1778
1779                 return $list;
1780         }
1781
1782         public function makeWhereFrom2d( $data, $baseKey, $subKey ) {
1783                 $conds = [];
1784
1785                 foreach ( $data as $base => $sub ) {
1786                         if ( count( $sub ) ) {
1787                                 $conds[] = $this->makeList(
1788                                         [ $baseKey => $base, $subKey => array_keys( $sub ) ],
1789                                         LIST_AND );
1790                         }
1791                 }
1792
1793                 if ( $conds ) {
1794                         return $this->makeList( $conds, LIST_OR );
1795                 } else {
1796                         // Nothing to search for...
1797                         return false;
1798                 }
1799         }
1800
1801         /**
1802          * Return aggregated value alias
1803          *
1804          * @param array $valuedata
1805          * @param string $valuename
1806          *
1807          * @return string
1808          */
1809         public function aggregateValue( $valuedata, $valuename = 'value' ) {
1810                 return $valuename;
1811         }
1812
1813         public function bitNot( $field ) {
1814                 return "(~$field)";
1815         }
1816
1817         public function bitAnd( $fieldLeft, $fieldRight ) {
1818                 return "($fieldLeft & $fieldRight)";
1819         }
1820
1821         public function bitOr( $fieldLeft, $fieldRight ) {
1822                 return "($fieldLeft | $fieldRight)";
1823         }
1824
1825         public function buildConcat( $stringList ) {
1826                 return 'CONCAT(' . implode( ',', $stringList ) . ')';
1827         }
1828
1829         public function buildGroupConcatField(
1830                 $delim, $table, $field, $conds = '', $join_conds = []
1831         ) {
1832                 $fld = "GROUP_CONCAT($field SEPARATOR " . $this->addQuotes( $delim ) . ')';
1833
1834                 return '(' . $this->selectSQLText( $table, $fld, $conds, null, [], $join_conds ) . ')';
1835         }
1836
1837         /**
1838          * @param string $field Field or column to cast
1839          * @return string
1840          * @since 1.28
1841          */
1842         public function buildStringCast( $field ) {
1843                 return $field;
1844         }
1845
1846         public function selectDB( $db ) {
1847                 # Stub. Shouldn't cause serious problems if it's not overridden, but
1848                 # if your database engine supports a concept similar to MySQL's
1849                 # databases you may as well.
1850                 $this->mDBname = $db;
1851
1852                 return true;
1853         }
1854
1855         public function getDBname() {
1856                 return $this->mDBname;
1857         }
1858
1859         public function getServer() {
1860                 return $this->mServer;
1861         }
1862
1863         /**
1864          * Format a table name ready for use in constructing an SQL query
1865          *
1866          * This does two important things: it quotes the table names to clean them up,
1867          * and it adds a table prefix if only given a table name with no quotes.
1868          *
1869          * All functions of this object which require a table name call this function
1870          * themselves. Pass the canonical name to such functions. This is only needed
1871          * when calling query() directly.
1872          *
1873          * @note This function does not sanitize user input. It is not safe to use
1874          *   this function to escape user input.
1875          * @param string $name Database table name
1876          * @param string $format One of:
1877          *   quoted - Automatically pass the table name through addIdentifierQuotes()
1878          *            so that it can be used in a query.
1879          *   raw - Do not add identifier quotes to the table name
1880          * @return string Full database name
1881          */
1882         public function tableName( $name, $format = 'quoted' ) {
1883                 global $wgSharedDB, $wgSharedPrefix, $wgSharedTables, $wgSharedSchema;
1884                 # Skip the entire process when we have a string quoted on both ends.
1885                 # Note that we check the end so that we will still quote any use of
1886                 # use of `database`.table. But won't break things if someone wants
1887                 # to query a database table with a dot in the name.
1888                 if ( $this->isQuotedIdentifier( $name ) ) {
1889                         return $name;
1890                 }
1891
1892                 # Lets test for any bits of text that should never show up in a table
1893                 # name. Basically anything like JOIN or ON which are actually part of
1894                 # SQL queries, but may end up inside of the table value to combine
1895                 # sql. Such as how the API is doing.
1896                 # Note that we use a whitespace test rather than a \b test to avoid
1897                 # any remote case where a word like on may be inside of a table name
1898                 # surrounded by symbols which may be considered word breaks.
1899                 if ( preg_match( '/(^|\s)(DISTINCT|JOIN|ON|AS)(\s|$)/i', $name ) !== 0 ) {
1900                         return $name;
1901                 }
1902
1903                 # Split database and table into proper variables.
1904                 # We reverse the explode so that database.table and table both output
1905                 # the correct table.
1906                 $dbDetails = explode( '.', $name, 3 );
1907                 if ( count( $dbDetails ) == 3 ) {
1908                         list( $database, $schema, $table ) = $dbDetails;
1909                         # We don't want any prefix added in this case
1910                         $prefix = '';
1911                 } elseif ( count( $dbDetails ) == 2 ) {
1912                         list( $database, $table ) = $dbDetails;
1913                         # We don't want any prefix added in this case
1914                         # In dbs that support it, $database may actually be the schema
1915                         # but that doesn't affect any of the functionality here
1916                         $prefix = '';
1917                         $schema = null;
1918                 } else {
1919                         list( $table ) = $dbDetails;
1920                         if ( $wgSharedDB !== null # We have a shared database
1921                                 && $this->mForeign == false # We're not working on a foreign database
1922                                 && !$this->isQuotedIdentifier( $table ) # Prevent shared tables listing '`table`'
1923                                 && in_array( $table, $wgSharedTables ) # A shared table is selected
1924                         ) {
1925                                 $database = $wgSharedDB;
1926                                 $schema = $wgSharedSchema === null ? $this->mSchema : $wgSharedSchema;
1927                                 $prefix = $wgSharedPrefix === null ? $this->mTablePrefix : $wgSharedPrefix;
1928                         } else {
1929                                 $database = null;
1930                                 $schema = $this->mSchema; # Default schema
1931                                 $prefix = $this->mTablePrefix; # Default prefix
1932                         }
1933                 }
1934
1935                 # Quote $table and apply the prefix if not quoted.
1936                 # $tableName might be empty if this is called from Database::replaceVars()
1937                 $tableName = "{$prefix}{$table}";
1938                 if ( $format == 'quoted' && !$this->isQuotedIdentifier( $tableName ) && $tableName !== '' ) {
1939                         $tableName = $this->addIdentifierQuotes( $tableName );
1940                 }
1941
1942                 # Quote $schema and merge it with the table name if needed
1943                 if ( strlen( $schema ) ) {
1944                         if ( $format == 'quoted' && !$this->isQuotedIdentifier( $schema ) ) {
1945                                 $schema = $this->addIdentifierQuotes( $schema );
1946                         }
1947                         $tableName = $schema . '.' . $tableName;
1948                 }
1949
1950                 # Quote $database and merge it with the table name if needed
1951                 if ( $database !== null ) {
1952                         if ( $format == 'quoted' && !$this->isQuotedIdentifier( $database ) ) {
1953                                 $database = $this->addIdentifierQuotes( $database );
1954                         }
1955                         $tableName = $database . '.' . $tableName;
1956                 }
1957
1958                 return $tableName;
1959         }
1960
1961         /**
1962          * Fetch a number of table names into an array
1963          * This is handy when you need to construct SQL for joins
1964          *
1965          * Example:
1966          * extract( $dbr->tableNames( 'user', 'watchlist' ) );
1967          * $sql = "SELECT wl_namespace,wl_title FROM $watchlist,$user
1968          *         WHERE wl_user=user_id AND wl_user=$nameWithQuotes";
1969          *
1970          * @return array
1971          */
1972         public function tableNames() {
1973                 $inArray = func_get_args();
1974                 $retVal = [];
1975
1976                 foreach ( $inArray as $name ) {
1977                         $retVal[$name] = $this->tableName( $name );
1978                 }
1979
1980                 return $retVal;
1981         }
1982
1983         /**
1984          * Fetch a number of table names into an zero-indexed numerical array
1985          * This is handy when you need to construct SQL for joins
1986          *
1987          * Example:
1988          * list( $user, $watchlist ) = $dbr->tableNamesN( 'user', 'watchlist' );
1989          * $sql = "SELECT wl_namespace,wl_title FROM $watchlist,$user
1990          *         WHERE wl_user=user_id AND wl_user=$nameWithQuotes";
1991          *
1992          * @return array
1993          */
1994         public function tableNamesN() {
1995                 $inArray = func_get_args();
1996                 $retVal = [];
1997
1998                 foreach ( $inArray as $name ) {
1999                         $retVal[] = $this->tableName( $name );
2000                 }
2001
2002                 return $retVal;
2003         }
2004
2005         /**
2006          * Get an aliased table name
2007          * e.g. tableName AS newTableName
2008          *
2009          * @param string $name Table name, see tableName()
2010          * @param string|bool $alias Alias (optional)
2011          * @return string SQL name for aliased table. Will not alias a table to its own name
2012          */
2013         public function tableNameWithAlias( $name, $alias = false ) {
2014                 if ( !$alias || $alias == $name ) {
2015                         return $this->tableName( $name );
2016                 } else {
2017                         return $this->tableName( $name ) . ' ' . $this->addIdentifierQuotes( $alias );
2018                 }
2019         }
2020
2021         /**
2022          * Gets an array of aliased table names
2023          *
2024          * @param array $tables [ [alias] => table ]
2025          * @return string[] See tableNameWithAlias()
2026          */
2027         public function tableNamesWithAlias( $tables ) {
2028                 $retval = [];
2029                 foreach ( $tables as $alias => $table ) {
2030                         if ( is_numeric( $alias ) ) {
2031                                 $alias = $table;
2032                         }
2033                         $retval[] = $this->tableNameWithAlias( $table, $alias );
2034                 }
2035
2036                 return $retval;
2037         }
2038
2039         /**
2040          * Get an aliased field name
2041          * e.g. fieldName AS newFieldName
2042          *
2043          * @param string $name Field name
2044          * @param string|bool $alias Alias (optional)
2045          * @return string SQL name for aliased field. Will not alias a field to its own name
2046          */
2047         public function fieldNameWithAlias( $name, $alias = false ) {
2048                 if ( !$alias || (string)$alias === (string)$name ) {
2049                         return $name;
2050                 } else {
2051                         return $name . ' AS ' . $this->addIdentifierQuotes( $alias ); // PostgreSQL needs AS
2052                 }
2053         }
2054
2055         /**
2056          * Gets an array of aliased field names
2057          *
2058          * @param array $fields [ [alias] => field ]
2059          * @return string[] See fieldNameWithAlias()
2060          */
2061         public function fieldNamesWithAlias( $fields ) {
2062                 $retval = [];
2063                 foreach ( $fields as $alias => $field ) {
2064                         if ( is_numeric( $alias ) ) {
2065                                 $alias = $field;
2066                         }
2067                         $retval[] = $this->fieldNameWithAlias( $field, $alias );
2068                 }
2069
2070                 return $retval;
2071         }
2072
2073         /**
2074          * Get the aliased table name clause for a FROM clause
2075          * which might have a JOIN and/or USE INDEX or IGNORE INDEX clause
2076          *
2077          * @param array $tables ( [alias] => table )
2078          * @param array $use_index Same as for select()
2079          * @param array $ignore_index Same as for select()
2080          * @param array $join_conds Same as for select()
2081          * @return string
2082          */
2083         protected function tableNamesWithIndexClauseOrJOIN(
2084                 $tables, $use_index = [], $ignore_index = [], $join_conds = []
2085         ) {
2086                 $ret = [];
2087                 $retJOIN = [];
2088                 $use_index = (array)$use_index;
2089                 $ignore_index = (array)$ignore_index;
2090                 $join_conds = (array)$join_conds;
2091
2092                 foreach ( $tables as $alias => $table ) {
2093                         if ( !is_string( $alias ) ) {
2094                                 // No alias? Set it equal to the table name
2095                                 $alias = $table;
2096                         }
2097                         // Is there a JOIN clause for this table?
2098                         if ( isset( $join_conds[$alias] ) ) {
2099                                 list( $joinType, $conds ) = $join_conds[$alias];
2100                                 $tableClause = $joinType;
2101                                 $tableClause .= ' ' . $this->tableNameWithAlias( $table, $alias );
2102                                 if ( isset( $use_index[$alias] ) ) { // has USE INDEX?
2103                                         $use = $this->useIndexClause( implode( ',', (array)$use_index[$alias] ) );
2104                                         if ( $use != '' ) {
2105                                                 $tableClause .= ' ' . $use;
2106                                         }
2107                                 }
2108                                 if ( isset( $ignore_index[$alias] ) ) { // has IGNORE INDEX?
2109                                         $ignore = $this->ignoreIndexClause( implode( ',', (array)$ignore_index[$alias] ) );
2110                                         if ( $ignore != '' ) {
2111                                                 $tableClause .= ' ' . $ignore;
2112                                         }
2113                                 }
2114                                 $on = $this->makeList( (array)$conds, LIST_AND );
2115                                 if ( $on != '' ) {
2116                                         $tableClause .= ' ON (' . $on . ')';
2117                                 }
2118
2119                                 $retJOIN[] = $tableClause;
2120                         } elseif ( isset( $use_index[$alias] ) ) {
2121                                 // Is there an INDEX clause for this table?
2122                                 $tableClause = $this->tableNameWithAlias( $table, $alias );
2123                                 $tableClause .= ' ' . $this->useIndexClause(
2124                                         implode( ',', (array)$use_index[$alias] )
2125                                 );
2126
2127                                 $ret[] = $tableClause;
2128                         } elseif ( isset( $ignore_index[$alias] ) ) {
2129                                 // Is there an INDEX clause for this table?
2130                                 $tableClause = $this->tableNameWithAlias( $table, $alias );
2131                                 $tableClause .= ' ' . $this->ignoreIndexClause(
2132                                         implode( ',', (array)$ignore_index[$alias] )
2133                                 );
2134
2135                                 $ret[] = $tableClause;
2136                         } else {
2137                                 $tableClause = $this->tableNameWithAlias( $table, $alias );
2138
2139                                 $ret[] = $tableClause;
2140                         }
2141                 }
2142
2143                 // We can't separate explicit JOIN clauses with ',', use ' ' for those
2144                 $implicitJoins = !empty( $ret ) ? implode( ',', $ret ) : "";
2145                 $explicitJoins = !empty( $retJOIN ) ? implode( ' ', $retJOIN ) : "";
2146
2147                 // Compile our final table clause
2148                 return implode( ' ', [ $implicitJoins, $explicitJoins ] );
2149         }
2150
2151         /**
2152          * Get the name of an index in a given table.
2153          *
2154          * @param string $index
2155          * @return string
2156          */
2157         protected function indexName( $index ) {
2158                 // Backwards-compatibility hack
2159                 $renamed = [
2160                         'ar_usertext_timestamp' => 'usertext_timestamp',
2161                         'un_user_id' => 'user_id',
2162                         'un_user_ip' => 'user_ip',
2163                 ];
2164
2165                 if ( isset( $renamed[$index] ) ) {
2166                         return $renamed[$index];
2167                 } else {
2168                         return $index;
2169                 }
2170         }
2171
2172         public function addQuotes( $s ) {
2173                 if ( $s instanceof Blob ) {
2174                         $s = $s->fetch();
2175                 }
2176                 if ( $s === null ) {
2177                         return 'NULL';
2178                 } else {
2179                         # This will also quote numeric values. This should be harmless,
2180                         # and protects against weird problems that occur when they really
2181                         # _are_ strings such as article titles and string->number->string
2182                         # conversion is not 1:1.
2183                         return "'" . $this->strencode( $s ) . "'";
2184                 }
2185         }
2186
2187         /**
2188          * Quotes an identifier using `backticks` or "double quotes" depending on the database type.
2189          * MySQL uses `backticks` while basically everything else uses double quotes.
2190          * Since MySQL is the odd one out here the double quotes are our generic
2191          * and we implement backticks in DatabaseMysql.
2192          *
2193          * @param string $s
2194          * @return string
2195          */
2196         public function addIdentifierQuotes( $s ) {
2197                 return '"' . str_replace( '"', '""', $s ) . '"';
2198         }
2199
2200         /**
2201          * Returns if the given identifier looks quoted or not according to
2202          * the database convention for quoting identifiers .
2203          *
2204          * @note Do not use this to determine if untrusted input is safe.
2205          *   A malicious user can trick this function.
2206          * @param string $name
2207          * @return bool
2208          */
2209         public function isQuotedIdentifier( $name ) {
2210                 return $name[0] == '"' && substr( $name, -1, 1 ) == '"';
2211         }
2212
2213         /**
2214          * @param string $s
2215          * @return string
2216          */
2217         protected function escapeLikeInternal( $s ) {
2218                 return addcslashes( $s, '\%_' );
2219         }
2220
2221         public function buildLike() {
2222                 $params = func_get_args();
2223
2224                 if ( count( $params ) > 0 && is_array( $params[0] ) ) {
2225                         $params = $params[0];
2226                 }
2227
2228                 $s = '';
2229
2230                 foreach ( $params as $value ) {
2231                         if ( $value instanceof LikeMatch ) {
2232                                 $s .= $value->toString();
2233                         } else {
2234                                 $s .= $this->escapeLikeInternal( $value );
2235                         }
2236                 }
2237
2238                 return " LIKE {$this->addQuotes( $s )} ";
2239         }
2240
2241         public function anyChar() {
2242                 return new LikeMatch( '_' );
2243         }
2244
2245         public function anyString() {
2246                 return new LikeMatch( '%' );
2247         }
2248
2249         public function nextSequenceValue( $seqName ) {
2250                 return null;
2251         }
2252
2253         /**
2254          * USE INDEX clause. Unlikely to be useful for anything but MySQL. This
2255          * is only needed because a) MySQL must be as efficient as possible due to
2256          * its use on Wikipedia, and b) MySQL 4.0 is kind of dumb sometimes about
2257          * which index to pick. Anyway, other databases might have different
2258          * indexes on a given table. So don't bother overriding this unless you're
2259          * MySQL.
2260          * @param string $index
2261          * @return string
2262          */
2263         public function useIndexClause( $index ) {
2264                 return '';
2265         }
2266
2267         /**
2268          * IGNORE INDEX clause. Unlikely to be useful for anything but MySQL. This
2269          * is only needed because a) MySQL must be as efficient as possible due to
2270          * its use on Wikipedia, and b) MySQL 4.0 is kind of dumb sometimes about
2271          * which index to pick. Anyway, other databases might have different
2272          * indexes on a given table. So don't bother overriding this unless you're
2273          * MySQL.
2274          * @param string $index
2275          * @return string
2276          */
2277         public function ignoreIndexClause( $index ) {
2278                 return '';
2279         }
2280
2281         public function replace( $table, $uniqueIndexes, $rows, $fname = __METHOD__ ) {
2282                 $quotedTable = $this->tableName( $table );
2283
2284                 if ( count( $rows ) == 0 ) {
2285                         return;
2286                 }
2287
2288                 # Single row case
2289                 if ( !is_array( reset( $rows ) ) ) {
2290                         $rows = [ $rows ];
2291                 }
2292
2293                 // @FXIME: this is not atomic, but a trx would break affectedRows()
2294                 foreach ( $rows as $row ) {
2295                         # Delete rows which collide
2296                         if ( $uniqueIndexes ) {
2297                                 $sql = "DELETE FROM $quotedTable WHERE ";
2298                                 $first = true;
2299                                 foreach ( $uniqueIndexes as $index ) {
2300                                         if ( $first ) {
2301                                                 $first = false;
2302                                                 $sql .= '( ';
2303                                         } else {
2304                                                 $sql .= ' ) OR ( ';
2305                                         }
2306                                         if ( is_array( $index ) ) {
2307                                                 $first2 = true;
2308                                                 foreach ( $index as $col ) {
2309                                                         if ( $first2 ) {
2310                                                                 $first2 = false;
2311                                                         } else {
2312                                                                 $sql .= ' AND ';
2313                                                         }
2314                                                         $sql .= $col . '=' . $this->addQuotes( $row[$col] );
2315                                                 }
2316                                         } else {
2317                                                 $sql .= $index . '=' . $this->addQuotes( $row[$index] );
2318                                         }
2319                                 }
2320                                 $sql .= ' )';
2321                                 $this->query( $sql, $fname );
2322                         }
2323
2324                         # Now insert the row
2325                         $this->insert( $table, $row, $fname );
2326                 }
2327         }
2328
2329         /**
2330          * REPLACE query wrapper for MySQL and SQLite, which have a native REPLACE
2331          * statement.
2332          *
2333          * @param string $table Table name
2334          * @param array|string $rows Row(s) to insert
2335          * @param string $fname Caller function name
2336          *
2337          * @return ResultWrapper
2338          */
2339         protected function nativeReplace( $table, $rows, $fname ) {
2340                 $table = $this->tableName( $table );
2341
2342                 # Single row case
2343                 if ( !is_array( reset( $rows ) ) ) {
2344                         $rows = [ $rows ];
2345                 }
2346
2347                 $sql = "REPLACE INTO $table (" . implode( ',', array_keys( $rows[0] ) ) . ') VALUES ';
2348                 $first = true;
2349
2350                 foreach ( $rows as $row ) {
2351                         if ( $first ) {
2352                                 $first = false;
2353                         } else {
2354                                 $sql .= ',';
2355                         }
2356
2357                         $sql .= '(' . $this->makeList( $row ) . ')';
2358                 }
2359
2360                 return $this->query( $sql, $fname );
2361         }
2362
2363         public function upsert( $table, array $rows, array $uniqueIndexes, array $set,
2364                 $fname = __METHOD__
2365         ) {
2366                 if ( !count( $rows ) ) {
2367                         return true; // nothing to do
2368                 }
2369
2370                 if ( !is_array( reset( $rows ) ) ) {
2371                         $rows = [ $rows ];
2372                 }
2373
2374                 if ( count( $uniqueIndexes ) ) {
2375                         $clauses = []; // list WHERE clauses that each identify a single row
2376                         foreach ( $rows as $row ) {
2377                                 foreach ( $uniqueIndexes as $index ) {
2378                                         $index = is_array( $index ) ? $index : [ $index ]; // columns
2379                                         $rowKey = []; // unique key to this row
2380                                         foreach ( $index as $column ) {
2381                                                 $rowKey[$column] = $row[$column];
2382                                         }
2383                                         $clauses[] = $this->makeList( $rowKey, LIST_AND );
2384                                 }
2385                         }
2386                         $where = [ $this->makeList( $clauses, LIST_OR ) ];
2387                 } else {
2388                         $where = false;
2389                 }
2390
2391                 $useTrx = !$this->mTrxLevel;
2392                 if ( $useTrx ) {
2393                         $this->begin( $fname, self::TRANSACTION_INTERNAL );
2394                 }
2395                 try {
2396                         # Update any existing conflicting row(s)
2397                         if ( $where !== false ) {
2398                                 $ok = $this->update( $table, $set, $where, $fname );
2399                         } else {
2400                                 $ok = true;
2401                         }
2402                         # Now insert any non-conflicting row(s)
2403                         $ok = $this->insert( $table, $rows, $fname, [ 'IGNORE' ] ) && $ok;
2404                 } catch ( Exception $e ) {
2405                         if ( $useTrx ) {
2406                                 $this->rollback( $fname, self::FLUSHING_INTERNAL );
2407                         }
2408                         throw $e;
2409                 }
2410                 if ( $useTrx ) {
2411                         $this->commit( $fname, self::FLUSHING_INTERNAL );
2412                 }
2413
2414                 return $ok;
2415         }
2416
2417         public function deleteJoin( $delTable, $joinTable, $delVar, $joinVar, $conds,
2418                 $fname = __METHOD__
2419         ) {
2420                 if ( !$conds ) {
2421                         throw new DBUnexpectedError( $this, __METHOD__ . ' called with empty $conds' );
2422                 }
2423
2424                 $delTable = $this->tableName( $delTable );
2425                 $joinTable = $this->tableName( $joinTable );
2426                 $sql = "DELETE FROM $delTable WHERE $delVar IN (SELECT $joinVar FROM $joinTable ";
2427                 if ( $conds != '*' ) {
2428                         $sql .= 'WHERE ' . $this->makeList( $conds, LIST_AND );
2429                 }
2430                 $sql .= ')';
2431
2432                 $this->query( $sql, $fname );
2433         }
2434
2435         /**
2436          * Returns the size of a text field, or -1 for "unlimited"
2437          *
2438          * @param string $table
2439          * @param string $field
2440          * @return int
2441          */
2442         public function textFieldSize( $table, $field ) {
2443                 $table = $this->tableName( $table );
2444                 $sql = "SHOW COLUMNS FROM $table LIKE \"$field\";";
2445                 $res = $this->query( $sql, __METHOD__ );
2446                 $row = $this->fetchObject( $res );
2447
2448                 $m = [];
2449
2450                 if ( preg_match( '/\((.*)\)/', $row->Type, $m ) ) {
2451                         $size = $m[1];
2452                 } else {
2453                         $size = -1;
2454                 }
2455
2456                 return $size;
2457         }
2458
2459         /**
2460          * A string to insert into queries to show that they're low-priority, like
2461          * MySQL's LOW_PRIORITY. If no such feature exists, return an empty
2462          * string and nothing bad should happen.
2463          *
2464          * @return string Returns the text of the low priority option if it is
2465          *   supported, or a blank string otherwise
2466          */
2467         public function lowPriorityOption() {
2468                 return '';
2469         }
2470
2471         public function delete( $table, $conds, $fname = __METHOD__ ) {
2472                 if ( !$conds ) {
2473                         throw new DBUnexpectedError( $this, __METHOD__ . ' called with no conditions' );
2474                 }
2475
2476                 $table = $this->tableName( $table );
2477                 $sql = "DELETE FROM $table";
2478
2479                 if ( $conds != '*' ) {
2480                         if ( is_array( $conds ) ) {
2481                                 $conds = $this->makeList( $conds, LIST_AND );
2482                         }
2483                         $sql .= ' WHERE ' . $conds;
2484                 }
2485
2486                 return $this->query( $sql, $fname );
2487         }
2488
2489         public function insertSelect(
2490                 $destTable, $srcTable, $varMap, $conds,
2491                 $fname = __METHOD__, $insertOptions = [], $selectOptions = []
2492         ) {
2493                 if ( $this->cliMode ) {
2494                         // For massive migrations with downtime, we don't want to select everything
2495                         // into memory and OOM, so do all this native on the server side if possible.
2496                         return $this->nativeInsertSelect(
2497                                 $destTable,
2498                                 $srcTable,
2499                                 $varMap,
2500                                 $conds,
2501                                 $fname,
2502                                 $insertOptions,
2503                                 $selectOptions
2504                         );
2505                 }
2506
2507                 // For web requests, do a locking SELECT and then INSERT. This puts the SELECT burden
2508                 // on only the master (without needing row-based-replication). It also makes it easy to
2509                 // know how big the INSERT is going to be.
2510                 $fields = [];
2511                 foreach ( $varMap as $dstColumn => $sourceColumnOrSql ) {
2512                         $fields[] = $this->fieldNameWithAlias( $sourceColumnOrSql, $dstColumn );
2513                 }
2514                 $selectOptions[] = 'FOR UPDATE';
2515                 $res = $this->select( $srcTable, implode( ',', $fields ), $conds, $fname, $selectOptions );
2516                 if ( !$res ) {
2517                         return false;
2518                 }
2519
2520                 $rows = [];
2521                 foreach ( $res as $row ) {
2522                         $rows[] = (array)$row;
2523                 }
2524
2525                 return $this->insert( $destTable, $rows, $fname, $insertOptions );
2526         }
2527
2528         public function nativeInsertSelect( $destTable, $srcTable, $varMap, $conds,
2529                 $fname = __METHOD__,
2530                 $insertOptions = [], $selectOptions = []
2531         ) {
2532                 $destTable = $this->tableName( $destTable );
2533
2534                 if ( !is_array( $insertOptions ) ) {
2535                         $insertOptions = [ $insertOptions ];
2536                 }
2537
2538                 $insertOptions = $this->makeInsertOptions( $insertOptions );
2539
2540                 if ( !is_array( $selectOptions ) ) {
2541                         $selectOptions = [ $selectOptions ];
2542                 }
2543
2544                 list( $startOpts, $useIndex, $tailOpts, $ignoreIndex ) = $this->makeSelectOptions(
2545                         $selectOptions );
2546
2547                 if ( is_array( $srcTable ) ) {
2548                         $srcTable = implode( ',', array_map( [ &$this, 'tableName' ], $srcTable ) );
2549                 } else {
2550                         $srcTable = $this->tableName( $srcTable );
2551                 }
2552
2553                 $sql = "INSERT $insertOptions INTO $destTable (" . implode( ',', array_keys( $varMap ) ) . ')' .
2554                         " SELECT $startOpts " . implode( ',', $varMap ) .
2555                         " FROM $srcTable $useIndex $ignoreIndex ";
2556
2557                 if ( $conds != '*' ) {
2558                         if ( is_array( $conds ) ) {
2559                                 $conds = $this->makeList( $conds, LIST_AND );
2560                         }
2561                         $sql .= " WHERE $conds";
2562                 }
2563
2564                 $sql .= " $tailOpts";
2565
2566                 return $this->query( $sql, $fname );
2567         }
2568
2569         /**
2570          * Construct a LIMIT query with optional offset. This is used for query
2571          * pages. The SQL should be adjusted so that only the first $limit rows
2572          * are returned. If $offset is provided as well, then the first $offset
2573          * rows should be discarded, and the next $limit rows should be returned.
2574          * If the result of the query is not ordered, then the rows to be returned
2575          * are theoretically arbitrary.
2576          *
2577          * $sql is expected to be a SELECT, if that makes a difference.
2578          *
2579          * The version provided by default works in MySQL and SQLite. It will very
2580          * likely need to be overridden for most other DBMSes.
2581          *
2582          * @param string $sql SQL query we will append the limit too
2583          * @param int $limit The SQL limit
2584          * @param int|bool $offset The SQL offset (default false)
2585          * @throws DBUnexpectedError
2586          * @return string
2587          */
2588         public function limitResult( $sql, $limit, $offset = false ) {
2589                 if ( !is_numeric( $limit ) ) {
2590                         throw new DBUnexpectedError( $this, "Invalid non-numeric limit passed to limitResult()\n" );
2591                 }
2592
2593                 return "$sql LIMIT "
2594                         . ( ( is_numeric( $offset ) && $offset != 0 ) ? "{$offset}," : "" )
2595                         . "{$limit} ";
2596         }
2597
2598         public function unionSupportsOrderAndLimit() {
2599                 return true; // True for almost every DB supported
2600         }
2601
2602         public function unionQueries( $sqls, $all ) {
2603                 $glue = $all ? ') UNION ALL (' : ') UNION (';
2604
2605                 return '(' . implode( $glue, $sqls ) . ')';
2606         }
2607
2608         public function conditional( $cond, $trueVal, $falseVal ) {
2609                 if ( is_array( $cond ) ) {
2610                         $cond = $this->makeList( $cond, LIST_AND );
2611                 }
2612
2613                 return " (CASE WHEN $cond THEN $trueVal ELSE $falseVal END) ";
2614         }
2615
2616         public function strreplace( $orig, $old, $new ) {
2617                 return "REPLACE({$orig}, {$old}, {$new})";
2618         }
2619
2620         public function getServerUptime() {
2621                 return 0;
2622         }
2623
2624         public function wasDeadlock() {
2625                 return false;
2626         }
2627
2628         public function wasLockTimeout() {
2629                 return false;
2630         }
2631
2632         public function wasErrorReissuable() {
2633                 return false;
2634         }
2635
2636         public function wasReadOnlyError() {
2637                 return false;
2638         }
2639
2640         /**
2641          * Determines if the given query error was a connection drop
2642          * STUB
2643          *
2644          * @param integer|string $errno
2645          * @return bool
2646          */
2647         public function wasConnectionError( $errno ) {
2648                 return false;
2649         }
2650
2651         /**
2652          * Perform a deadlock-prone transaction.
2653          *
2654          * This function invokes a callback function to perform a set of write
2655          * queries. If a deadlock occurs during the processing, the transaction
2656          * will be rolled back and the callback function will be called again.
2657          *
2658          * Avoid using this method outside of Job or Maintenance classes.
2659          *
2660          * Usage:
2661          *   $dbw->deadlockLoop( callback, ... );
2662          *
2663          * Extra arguments are passed through to the specified callback function.
2664          * This method requires that no transactions are already active to avoid
2665          * causing premature commits or exceptions.
2666          *
2667          * Returns whatever the callback function returned on its successful,
2668          * iteration, or false on error, for example if the retry limit was
2669          * reached.
2670          *
2671          * @return mixed
2672          * @throws DBUnexpectedError
2673          * @throws Exception
2674          */
2675         public function deadlockLoop() {
2676                 $args = func_get_args();
2677                 $function = array_shift( $args );
2678                 $tries = self::DEADLOCK_TRIES;
2679
2680                 $this->begin( __METHOD__ );
2681
2682                 $retVal = null;
2683                 /** @var Exception $e */
2684                 $e = null;
2685                 do {
2686                         try {
2687                                 $retVal = call_user_func_array( $function, $args );
2688                                 break;
2689                         } catch ( DBQueryError $e ) {
2690                                 if ( $this->wasDeadlock() ) {
2691                                         // Retry after a randomized delay
2692                                         usleep( mt_rand( self::DEADLOCK_DELAY_MIN, self::DEADLOCK_DELAY_MAX ) );
2693                                 } else {
2694                                         // Throw the error back up
2695                                         throw $e;
2696                                 }
2697                         }
2698                 } while ( --$tries > 0 );
2699
2700                 if ( $tries <= 0 ) {
2701                         // Too many deadlocks; give up
2702                         $this->rollback( __METHOD__ );
2703                         throw $e;
2704                 } else {
2705                         $this->commit( __METHOD__ );
2706
2707                         return $retVal;
2708                 }
2709         }
2710
2711         public function masterPosWait( DBMasterPos $pos, $timeout ) {
2712                 # Real waits are implemented in the subclass.
2713                 return 0;
2714         }
2715
2716         public function getSlavePos() {
2717                 # Stub
2718                 return false;
2719         }
2720
2721         public function getMasterPos() {
2722                 # Stub
2723                 return false;
2724         }
2725
2726         public function serverIsReadOnly() {
2727                 return false;
2728         }
2729
2730         final public function onTransactionResolution( callable $callback ) {
2731                 if ( !$this->mTrxLevel ) {
2732                         throw new DBUnexpectedError( $this, "No transaction is active." );
2733                 }
2734                 $this->mTrxEndCallbacks[] = [ $callback, wfGetCaller() ];
2735         }
2736
2737         final public function onTransactionIdle( callable $callback ) {
2738                 $this->mTrxIdleCallbacks[] = [ $callback, wfGetCaller() ];
2739                 if ( !$this->mTrxLevel ) {
2740                         $this->runOnTransactionIdleCallbacks( self::TRIGGER_IDLE );
2741                 }
2742         }
2743
2744         final public function onTransactionPreCommitOrIdle( callable $callback ) {
2745                 if ( $this->mTrxLevel ) {
2746                         $this->mTrxPreCommitCallbacks[] = [ $callback, wfGetCaller() ];
2747                 } else {
2748                         // If no transaction is active, then make one for this callback
2749                         $this->startAtomic( __METHOD__ );
2750                         try {
2751                                 call_user_func( $callback );
2752                                 $this->endAtomic( __METHOD__ );
2753                         } catch ( Exception $e ) {
2754                                 $this->rollback( __METHOD__, self::FLUSHING_INTERNAL );
2755                                 throw $e;
2756                         }
2757                 }
2758         }
2759
2760         final public function setTransactionListener( $name, callable $callback = null ) {
2761                 if ( $callback ) {
2762                         $this->mTrxRecurringCallbacks[$name] = [ $callback, wfGetCaller() ];
2763                 } else {
2764                         unset( $this->mTrxRecurringCallbacks[$name] );
2765                 }
2766         }
2767
2768         /**
2769          * Whether to disable running of post-COMMIT/ROLLBACK callbacks
2770          *
2771          * This method should not be used outside of Database/LoadBalancer
2772          *
2773          * @param bool $suppress
2774          * @since 1.28
2775          */
2776         final public function setTrxEndCallbackSuppression( $suppress ) {
2777                 $this->mTrxEndCallbacksSuppressed = $suppress;
2778         }
2779
2780         /**
2781          * Actually run and consume any "on transaction idle/resolution" callbacks.
2782          *
2783          * This method should not be used outside of Database/LoadBalancer
2784          *
2785          * @param integer $trigger IDatabase::TRIGGER_* constant
2786          * @since 1.20
2787          * @throws Exception
2788          */
2789         public function runOnTransactionIdleCallbacks( $trigger ) {
2790                 if ( $this->mTrxEndCallbacksSuppressed ) {
2791                         return;
2792                 }
2793
2794                 $autoTrx = $this->getFlag( DBO_TRX ); // automatic begin() enabled?
2795                 /** @var Exception $e */
2796                 $e = null; // first exception
2797                 do { // callbacks may add callbacks :)
2798                         $callbacks = array_merge(
2799                                 $this->mTrxIdleCallbacks,
2800                                 $this->mTrxEndCallbacks // include "transaction resolution" callbacks
2801                         );
2802                         $this->mTrxIdleCallbacks = []; // consumed (and recursion guard)
2803                         $this->mTrxEndCallbacks = []; // consumed (recursion guard)
2804                         foreach ( $callbacks as $callback ) {
2805                                 try {
2806                                         list( $phpCallback ) = $callback;
2807                                         $this->clearFlag( DBO_TRX ); // make each query its own transaction
2808                                         call_user_func_array( $phpCallback, [ $trigger ] );
2809                                         if ( $autoTrx ) {
2810                                                 $this->setFlag( DBO_TRX ); // restore automatic begin()
2811                                         } else {
2812                                                 $this->clearFlag( DBO_TRX ); // restore auto-commit
2813                                         }
2814                                 } catch ( Exception $ex ) {
2815                                         call_user_func( $this->errorLogger, $ex );
2816                                         $e = $e ?: $ex;
2817                                         // Some callbacks may use startAtomic/endAtomic, so make sure
2818                                         // their transactions are ended so other callbacks don't fail
2819                                         if ( $this->trxLevel() ) {
2820                                                 $this->rollback( __METHOD__, self::FLUSHING_INTERNAL );
2821                                         }
2822                                 }
2823                         }
2824                 } while ( count( $this->mTrxIdleCallbacks ) );
2825
2826                 if ( $e instanceof Exception ) {
2827                         throw $e; // re-throw any first exception
2828                 }
2829         }
2830
2831         /**
2832          * Actually run and consume any "on transaction pre-commit" callbacks.
2833          *
2834          * This method should not be used outside of Database/LoadBalancer
2835          *
2836          * @since 1.22
2837          * @throws Exception
2838          */
2839         public function runOnTransactionPreCommitCallbacks() {
2840                 $e = null; // first exception
2841                 do { // callbacks may add callbacks :)
2842                         $callbacks = $this->mTrxPreCommitCallbacks;
2843                         $this->mTrxPreCommitCallbacks = []; // consumed (and recursion guard)
2844                         foreach ( $callbacks as $callback ) {
2845                                 try {
2846                                         list( $phpCallback ) = $callback;
2847                                         call_user_func( $phpCallback );
2848                                 } catch ( Exception $ex ) {
2849                                         call_user_func( $this->errorLogger, $ex );
2850                                         $e = $e ?: $ex;
2851                                 }
2852                         }
2853                 } while ( count( $this->mTrxPreCommitCallbacks ) );
2854
2855                 if ( $e instanceof Exception ) {
2856                         throw $e; // re-throw any first exception
2857                 }
2858         }
2859
2860         /**
2861          * Actually run any "transaction listener" callbacks.
2862          *
2863          * This method should not be used outside of Database/LoadBalancer
2864          *
2865          * @param integer $trigger IDatabase::TRIGGER_* constant
2866          * @throws Exception
2867          * @since 1.20
2868          */
2869         public function runTransactionListenerCallbacks( $trigger ) {
2870                 if ( $this->mTrxEndCallbacksSuppressed ) {
2871                         return;
2872                 }
2873
2874                 /** @var Exception $e */
2875                 $e = null; // first exception
2876
2877                 foreach ( $this->mTrxRecurringCallbacks as $callback ) {
2878                         try {
2879                                 list( $phpCallback ) = $callback;
2880                                 $phpCallback( $trigger, $this );
2881                         } catch ( Exception $ex ) {
2882                                 call_user_func( $this->errorLogger, $ex );
2883                                 $e = $e ?: $ex;
2884                         }
2885                 }
2886
2887                 if ( $e instanceof Exception ) {
2888                         throw $e; // re-throw any first exception
2889                 }
2890         }
2891
2892         final public function startAtomic( $fname = __METHOD__ ) {
2893                 if ( !$this->mTrxLevel ) {
2894                         $this->begin( $fname, self::TRANSACTION_INTERNAL );
2895                         // If DBO_TRX is set, a series of startAtomic/endAtomic pairs will result
2896                         // in all changes being in one transaction to keep requests transactional.
2897                         if ( !$this->getFlag( DBO_TRX ) ) {
2898                                 $this->mTrxAutomaticAtomic = true;
2899                         }
2900                 }
2901
2902                 $this->mTrxAtomicLevels[] = $fname;
2903         }
2904
2905         final public function endAtomic( $fname = __METHOD__ ) {
2906                 if ( !$this->mTrxLevel ) {
2907                         throw new DBUnexpectedError( $this, "No atomic transaction is open (got $fname)." );
2908                 }
2909                 if ( !$this->mTrxAtomicLevels ||
2910                         array_pop( $this->mTrxAtomicLevels ) !== $fname
2911                 ) {
2912                         throw new DBUnexpectedError( $this, "Invalid atomic section ended (got $fname)." );
2913                 }
2914
2915                 if ( !$this->mTrxAtomicLevels && $this->mTrxAutomaticAtomic ) {
2916                         $this->commit( $fname, self::FLUSHING_INTERNAL );
2917                 }
2918         }
2919
2920         final public function doAtomicSection( $fname, callable $callback ) {
2921                 $this->startAtomic( $fname );
2922                 try {
2923                         $res = call_user_func_array( $callback, [ $this, $fname ] );
2924                 } catch ( Exception $e ) {
2925                         $this->rollback( $fname, self::FLUSHING_INTERNAL );
2926                         throw $e;
2927                 }
2928                 $this->endAtomic( $fname );
2929
2930                 return $res;
2931         }
2932
2933         final public function begin( $fname = __METHOD__, $mode = self::TRANSACTION_EXPLICIT ) {
2934                 // Protect against mismatched atomic section, transaction nesting, and snapshot loss
2935                 if ( $this->mTrxLevel ) {
2936                         if ( $this->mTrxAtomicLevels ) {
2937                                 $levels = implode( ', ', $this->mTrxAtomicLevels );
2938                                 $msg = "$fname: Got explicit BEGIN while atomic section(s) $levels are open.";
2939                                 throw new DBUnexpectedError( $this, $msg );
2940                         } elseif ( !$this->mTrxAutomatic ) {
2941                                 $msg = "$fname: Explicit transaction already active (from {$this->mTrxFname}).";
2942                                 throw new DBUnexpectedError( $this, $msg );
2943                         } else {
2944                                 // @TODO: make this an exception at some point
2945                                 $msg = "$fname: Implicit transaction already active (from {$this->mTrxFname}).";
2946                                 $this->queryLogger->error( $msg );
2947                                 return; // join the main transaction set
2948                         }
2949                 } elseif ( $this->getFlag( DBO_TRX ) && $mode !== self::TRANSACTION_INTERNAL ) {
2950                         // @TODO: make this an exception at some point
2951                         $msg = "$fname: Implicit transaction expected (DBO_TRX set).";
2952                         $this->queryLogger->error( $msg );
2953                         return; // let any writes be in the main transaction
2954                 }
2955
2956                 // Avoid fatals if close() was called
2957                 $this->assertOpen();
2958
2959                 $this->doBegin( $fname );
2960                 $this->mTrxTimestamp = microtime( true );
2961                 $this->mTrxFname = $fname;
2962                 $this->mTrxDoneWrites = false;
2963                 $this->mTrxAutomatic = ( $mode === self::TRANSACTION_INTERNAL );
2964                 $this->mTrxAutomaticAtomic = false;
2965                 $this->mTrxAtomicLevels = [];
2966                 $this->mTrxShortId = wfRandomString( 12 );
2967                 $this->mTrxWriteDuration = 0.0;
2968                 $this->mTrxWriteQueryCount = 0;
2969                 $this->mTrxWriteAdjDuration = 0.0;
2970                 $this->mTrxWriteAdjQueryCount = 0;
2971                 $this->mTrxWriteCallers = [];
2972                 // First SELECT after BEGIN will establish the snapshot in REPEATABLE-READ.
2973                 // Get an estimate of the replica DB lag before then, treating estimate staleness
2974                 // as lag itself just to be safe
2975                 $status = $this->getApproximateLagStatus();
2976                 $this->mTrxReplicaLag = $status['lag'] + ( microtime( true ) - $status['since'] );
2977         }
2978
2979         /**
2980          * Issues the BEGIN command to the database server.
2981          *
2982          * @see DatabaseBase::begin()
2983          * @param string $fname
2984          */
2985         protected function doBegin( $fname ) {
2986                 $this->query( 'BEGIN', $fname );
2987                 $this->mTrxLevel = 1;
2988         }
2989
2990         final public function commit( $fname = __METHOD__, $flush = '' ) {
2991                 if ( $this->mTrxLevel && $this->mTrxAtomicLevels ) {
2992                         // There are still atomic sections open. This cannot be ignored
2993                         $levels = implode( ', ', $this->mTrxAtomicLevels );
2994                         throw new DBUnexpectedError(
2995                                 $this,
2996                                 "$fname: Got COMMIT while atomic sections $levels are still open."
2997                         );
2998                 }
2999
3000                 if ( $flush === self::FLUSHING_INTERNAL || $flush === self::FLUSHING_ALL_PEERS ) {
3001                         if ( !$this->mTrxLevel ) {
3002                                 return; // nothing to do
3003                         } elseif ( !$this->mTrxAutomatic ) {
3004                                 throw new DBUnexpectedError(
3005                                         $this,
3006                                         "$fname: Flushing an explicit transaction, getting out of sync."
3007                                 );
3008                         }
3009                 } else {
3010                         if ( !$this->mTrxLevel ) {
3011                                 $this->queryLogger->error( "$fname: No transaction to commit, something got out of sync." );
3012                                 return; // nothing to do
3013                         } elseif ( $this->mTrxAutomatic ) {
3014                                 // @TODO: make this an exception at some point
3015                                 $msg = "$fname: Explicit commit of implicit transaction.";
3016                                 $this->queryLogger->error( $msg );
3017                                 return; // wait for the main transaction set commit round
3018                         }
3019                 }
3020
3021                 // Avoid fatals if close() was called
3022                 $this->assertOpen();
3023
3024                 $this->runOnTransactionPreCommitCallbacks();
3025                 $writeTime = $this->pendingWriteQueryDuration( self::ESTIMATE_DB_APPLY );
3026                 $this->doCommit( $fname );
3027                 if ( $this->mTrxDoneWrites ) {
3028                         $this->mDoneWrites = microtime( true );
3029                         $this->trxProfiler->transactionWritingOut(
3030                                 $this->mServer, $this->mDBname, $this->mTrxShortId, $writeTime );
3031                 }
3032
3033                 $this->runOnTransactionIdleCallbacks( self::TRIGGER_COMMIT );
3034                 $this->runTransactionListenerCallbacks( self::TRIGGER_COMMIT );
3035         }
3036
3037         /**
3038          * Issues the COMMIT command to the database server.
3039          *
3040          * @see DatabaseBase::commit()
3041          * @param string $fname
3042          */
3043         protected function doCommit( $fname ) {
3044                 if ( $this->mTrxLevel ) {
3045                         $this->query( 'COMMIT', $fname );
3046                         $this->mTrxLevel = 0;
3047                 }
3048         }
3049
3050         final public function rollback( $fname = __METHOD__, $flush = '' ) {
3051                 if ( $flush === self::FLUSHING_INTERNAL || $flush === self::FLUSHING_ALL_PEERS ) {
3052                         if ( !$this->mTrxLevel ) {
3053                                 return; // nothing to do
3054                         }
3055                 } else {
3056                         if ( !$this->mTrxLevel ) {
3057                                 $this->queryLogger->error(
3058                                         "$fname: No transaction to rollback, something got out of sync." );
3059                                 return; // nothing to do
3060                         } elseif ( $this->getFlag( DBO_TRX ) ) {
3061                                 throw new DBUnexpectedError(
3062                                         $this,
3063                                         "$fname: Expected mass rollback of all peer databases (DBO_TRX set)."
3064                                 );
3065                         }
3066                 }
3067
3068                 // Avoid fatals if close() was called
3069                 $this->assertOpen();
3070
3071                 $this->doRollback( $fname );
3072                 $this->mTrxAtomicLevels = [];
3073                 if ( $this->mTrxDoneWrites ) {
3074                         $this->trxProfiler->transactionWritingOut(
3075                                 $this->mServer, $this->mDBname, $this->mTrxShortId );
3076                 }
3077
3078                 $this->mTrxIdleCallbacks = []; // clear
3079                 $this->mTrxPreCommitCallbacks = []; // clear
3080                 $this->runOnTransactionIdleCallbacks( self::TRIGGER_ROLLBACK );
3081                 $this->runTransactionListenerCallbacks( self::TRIGGER_ROLLBACK );
3082         }
3083
3084         /**
3085          * Issues the ROLLBACK command to the database server.
3086          *
3087          * @see DatabaseBase::rollback()
3088          * @param string $fname
3089          */
3090         protected function doRollback( $fname ) {
3091                 if ( $this->mTrxLevel ) {
3092                         # Disconnects cause rollback anyway, so ignore those errors
3093                         $ignoreErrors = true;
3094                         $this->query( 'ROLLBACK', $fname, $ignoreErrors );
3095                         $this->mTrxLevel = 0;
3096                 }
3097         }
3098
3099         public function flushSnapshot( $fname = __METHOD__ ) {
3100                 if ( $this->writesOrCallbacksPending() || $this->explicitTrxActive() ) {
3101                         // This only flushes transactions to clear snapshots, not to write data
3102                         throw new DBUnexpectedError(
3103                                 $this,
3104                                 "$fname: Cannot COMMIT to clear snapshot because writes are pending."
3105                         );
3106                 }
3107
3108                 $this->commit( $fname, self::FLUSHING_INTERNAL );
3109         }
3110
3111         public function explicitTrxActive() {
3112                 return $this->mTrxLevel && ( $this->mTrxAtomicLevels || !$this->mTrxAutomatic );
3113         }
3114
3115         /**
3116          * Creates a new table with structure copied from existing table
3117          * Note that unlike most database abstraction functions, this function does not
3118          * automatically append database prefix, because it works at a lower
3119          * abstraction level.
3120          * The table names passed to this function shall not be quoted (this
3121          * function calls addIdentifierQuotes when needed).
3122          *
3123          * @param string $oldName Name of table whose structure should be copied
3124          * @param string $newName Name of table to be created
3125          * @param bool $temporary Whether the new table should be temporary
3126          * @param string $fname Calling function name
3127          * @throws RuntimeException
3128          * @return bool True if operation was successful
3129          */
3130         public function duplicateTableStructure( $oldName, $newName, $temporary = false,
3131                 $fname = __METHOD__
3132         ) {
3133                 throw new RuntimeException( __METHOD__ . ' is not implemented in descendant class' );
3134         }
3135
3136         function listTables( $prefix = null, $fname = __METHOD__ ) {
3137                 throw new RuntimeException( __METHOD__ . ' is not implemented in descendant class' );
3138         }
3139
3140         /**
3141          * Reset the views process cache set by listViews()
3142          * @since 1.22
3143          */
3144         final public function clearViewsCache() {
3145                 $this->allViews = null;
3146         }
3147
3148         /**
3149          * Lists all the VIEWs in the database
3150          *
3151          * For caching purposes the list of all views should be stored in
3152          * $this->allViews. The process cache can be cleared with clearViewsCache()
3153          *
3154          * @param string $prefix Only show VIEWs with this prefix, eg. unit_test_
3155          * @param string $fname Name of calling function
3156          * @throws RuntimeException
3157          * @return array
3158          * @since 1.22
3159          */
3160         public function listViews( $prefix = null, $fname = __METHOD__ ) {
3161                 throw new RuntimeException( __METHOD__ . ' is not implemented in descendant class' );
3162         }
3163
3164         /**
3165          * Differentiates between a TABLE and a VIEW
3166          *
3167          * @param string $name Name of the database-structure to test.
3168          * @throws RuntimeException
3169          * @return bool
3170          * @since 1.22
3171          */
3172         public function isView( $name ) {
3173                 throw new RuntimeException( __METHOD__ . ' is not implemented in descendant class' );
3174         }
3175
3176         public function timestamp( $ts = 0 ) {
3177                 return wfTimestamp( TS_MW, $ts );
3178         }
3179
3180         public function timestampOrNull( $ts = null ) {
3181                 if ( is_null( $ts ) ) {
3182                         return null;
3183                 } else {
3184                         return $this->timestamp( $ts );
3185                 }
3186         }
3187
3188         /**
3189          * Take the result from a query, and wrap it in a ResultWrapper if
3190          * necessary. Boolean values are passed through as is, to indicate success
3191          * of write queries or failure.
3192          *
3193          * Once upon a time, DatabaseBase::query() returned a bare MySQL result
3194          * resource, and it was necessary to call this function to convert it to
3195          * a wrapper. Nowadays, raw database objects are never exposed to external
3196          * callers, so this is unnecessary in external code.
3197          *
3198          * @param bool|ResultWrapper|resource|object $result
3199          * @return bool|ResultWrapper
3200          */
3201         protected function resultObject( $result ) {
3202                 if ( !$result ) {
3203                         return false;
3204                 } elseif ( $result instanceof ResultWrapper ) {
3205                         return $result;
3206                 } elseif ( $result === true ) {
3207                         // Successful write query
3208                         return $result;
3209                 } else {
3210                         return new ResultWrapper( $this, $result );
3211                 }
3212         }
3213
3214         public function ping( &$rtt = null ) {
3215                 // Avoid hitting the server if it was hit recently
3216                 if ( $this->isOpen() && ( microtime( true ) - $this->lastPing ) < self::PING_TTL ) {
3217                         if ( !func_num_args() || $this->mRTTEstimate > 0 ) {
3218                                 $rtt = $this->mRTTEstimate;
3219                                 return true; // don't care about $rtt
3220                         }
3221                 }
3222
3223                 // This will reconnect if possible or return false if not
3224                 $this->clearFlag( DBO_TRX, self::REMEMBER_PRIOR );
3225                 $ok = ( $this->query( self::PING_QUERY, __METHOD__, true ) !== false );
3226                 $this->restoreFlags( self::RESTORE_PRIOR );
3227
3228                 if ( $ok ) {
3229                         $rtt = $this->mRTTEstimate;
3230                 }
3231
3232                 return $ok;
3233         }
3234
3235         /**
3236          * @return bool
3237          */
3238         protected function reconnect() {
3239                 $this->closeConnection();
3240                 $this->mOpened = false;
3241                 $this->mConn = false;
3242                 try {
3243                         $this->open( $this->mServer, $this->mUser, $this->mPassword, $this->mDBname );
3244                         $this->lastPing = microtime( true );
3245                         $ok = true;
3246                 } catch ( DBConnectionError $e ) {
3247                         $ok = false;
3248                 }
3249
3250                 return $ok;
3251         }
3252
3253         public function getSessionLagStatus() {
3254                 return $this->getTransactionLagStatus() ?: $this->getApproximateLagStatus();
3255         }
3256
3257         /**
3258          * Get the replica DB lag when the current transaction started
3259          *
3260          * This is useful when transactions might use snapshot isolation
3261          * (e.g. REPEATABLE-READ in innodb), so the "real" lag of that data
3262          * is this lag plus transaction duration. If they don't, it is still
3263          * safe to be pessimistic. This returns null if there is no transaction.
3264          *
3265          * @return array|null ('lag': seconds or false on error, 'since': UNIX timestamp of BEGIN)
3266          * @since 1.27
3267          */
3268         public function getTransactionLagStatus() {
3269                 return $this->mTrxLevel
3270                         ? [ 'lag' => $this->mTrxReplicaLag, 'since' => $this->trxTimestamp() ]
3271                         : null;
3272         }
3273
3274         /**
3275          * Get a replica DB lag estimate for this server
3276          *
3277          * @return array ('lag': seconds or false on error, 'since': UNIX timestamp of estimate)
3278          * @since 1.27
3279          */
3280         public function getApproximateLagStatus() {
3281                 return [
3282                         'lag'   => $this->getLBInfo( 'replica' ) ? $this->getLag() : 0,
3283                         'since' => microtime( true )
3284                 ];
3285         }
3286
3287         /**
3288          * Merge the result of getSessionLagStatus() for several DBs
3289          * using the most pessimistic values to estimate the lag of
3290          * any data derived from them in combination
3291          *
3292          * This is information is useful for caching modules
3293          *
3294          * @see WANObjectCache::set()
3295          * @see WANObjectCache::getWithSetCallback()
3296          *
3297          * @param IDatabase $db1
3298          * @param IDatabase ...
3299          * @return array Map of values:
3300          *   - lag: highest lag of any of the DBs or false on error (e.g. replication stopped)
3301          *   - since: oldest UNIX timestamp of any of the DB lag estimates
3302          *   - pending: whether any of the DBs have uncommitted changes
3303          * @since 1.27
3304          */
3305         public static function getCacheSetOptions( IDatabase $db1 ) {
3306                 $res = [ 'lag' => 0, 'since' => INF, 'pending' => false ];
3307                 foreach ( func_get_args() as $db ) {
3308                         /** @var IDatabase $db */
3309                         $status = $db->getSessionLagStatus();
3310                         if ( $status['lag'] === false ) {
3311                                 $res['lag'] = false;
3312                         } elseif ( $res['lag'] !== false ) {
3313                                 $res['lag'] = max( $res['lag'], $status['lag'] );
3314                         }
3315                         $res['since'] = min( $res['since'], $status['since'] );
3316                         $res['pending'] = $res['pending'] ?: $db->writesPending();
3317                 }
3318
3319                 return $res;
3320         }
3321
3322         public function getLag() {
3323                 return 0;
3324         }
3325
3326         function maxListLen() {
3327                 return 0;
3328         }
3329
3330         public function encodeBlob( $b ) {
3331                 return $b;
3332         }
3333
3334         public function decodeBlob( $b ) {
3335                 if ( $b instanceof Blob ) {
3336                         $b = $b->fetch();
3337                 }
3338                 return $b;
3339         }
3340
3341         public function setSessionOptions( array $options ) {
3342         }
3343
3344         /**
3345          * Read and execute SQL commands from a file.
3346          *
3347          * Returns true on success, error string or exception on failure (depending
3348          * on object's error ignore settings).
3349          *
3350          * @param string $filename File name to open
3351          * @param bool|callable $lineCallback Optional function called before reading each line
3352          * @param bool|callable $resultCallback Optional function called for each MySQL result
3353          * @param bool|string $fname Calling function name or false if name should be
3354          *   generated dynamically using $filename
3355          * @param bool|callable $inputCallback Optional function called for each
3356          *   complete line sent
3357          * @return bool|string
3358          * @throws Exception
3359          */
3360         public function sourceFile(
3361                 $filename, $lineCallback = false, $resultCallback = false, $fname = false, $inputCallback = false
3362         ) {
3363                 MediaWiki\suppressWarnings();
3364                 $fp = fopen( $filename, 'r' );
3365                 MediaWiki\restoreWarnings();
3366
3367                 if ( false === $fp ) {
3368                         throw new RuntimeException( "Could not open \"{$filename}\".\n" );
3369                 }
3370
3371                 if ( !$fname ) {
3372                         $fname = __METHOD__ . "( $filename )";
3373                 }
3374
3375                 try {
3376                         $error = $this->sourceStream( $fp, $lineCallback, $resultCallback, $fname, $inputCallback );
3377                 } catch ( Exception $e ) {
3378                         fclose( $fp );
3379                         throw $e;
3380                 }
3381
3382                 fclose( $fp );
3383
3384                 return $error;
3385         }
3386
3387         /**
3388          * Get the full path of a patch file. Originally based on archive()
3389          * from updaters.inc. Keep in mind this always returns a patch, as
3390          * it fails back to MySQL if no DB-specific patch can be found
3391          *
3392          * @param string $patch The name of the patch, like patch-something.sql
3393          * @return string Full path to patch file
3394          */
3395         public function patchPath( $patch ) {
3396                 global $IP;
3397
3398                 $dbType = $this->getType();
3399                 if ( file_exists( "$IP/maintenance/$dbType/archives/$patch" ) ) {
3400                         return "$IP/maintenance/$dbType/archives/$patch";
3401                 } else {
3402                         return "$IP/maintenance/archives/$patch";
3403                 }
3404         }
3405
3406         public function setSchemaVars( $vars ) {
3407                 $this->mSchemaVars = $vars;
3408         }
3409
3410         /**
3411          * Read and execute commands from an open file handle.
3412          *
3413          * Returns true on success, error string or exception on failure (depending
3414          * on object's error ignore settings).
3415          *
3416          * @param resource $fp File handle
3417          * @param bool|callable $lineCallback Optional function called before reading each query
3418          * @param bool|callable $resultCallback Optional function called for each MySQL result
3419          * @param string $fname Calling function name
3420          * @param bool|callable $inputCallback Optional function called for each complete query sent
3421          * @return bool|string
3422          */
3423         public function sourceStream( $fp, $lineCallback = false, $resultCallback = false,
3424                 $fname = __METHOD__, $inputCallback = false
3425         ) {
3426                 $cmd = '';
3427
3428                 while ( !feof( $fp ) ) {
3429                         if ( $lineCallback ) {
3430                                 call_user_func( $lineCallback );
3431                         }
3432
3433                         $line = trim( fgets( $fp ) );
3434
3435                         if ( $line == '' ) {
3436                                 continue;
3437                         }
3438
3439                         if ( '-' == $line[0] && '-' == $line[1] ) {
3440                                 continue;
3441                         }
3442
3443                         if ( $cmd != '' ) {
3444                                 $cmd .= ' ';
3445                         }
3446
3447                         $done = $this->streamStatementEnd( $cmd, $line );
3448
3449                         $cmd .= "$line\n";
3450
3451                         if ( $done || feof( $fp ) ) {
3452                                 $cmd = $this->replaceVars( $cmd );
3453
3454                                 if ( ( $inputCallback && call_user_func( $inputCallback, $cmd ) ) || !$inputCallback ) {
3455                                         $res = $this->query( $cmd, $fname );
3456
3457                                         if ( $resultCallback ) {
3458                                                 call_user_func( $resultCallback, $res, $this );
3459                                         }
3460
3461                                         if ( false === $res ) {
3462                                                 $err = $this->lastError();
3463
3464                                                 return "Query \"{$cmd}\" failed with error code \"$err\".\n";
3465                                         }
3466                                 }
3467                                 $cmd = '';
3468                         }
3469                 }
3470
3471                 return true;
3472         }
3473
3474         /**
3475          * Called by sourceStream() to check if we've reached a statement end
3476          *
3477          * @param string $sql SQL assembled so far
3478          * @param string $newLine New line about to be added to $sql
3479          * @return bool Whether $newLine contains end of the statement
3480          */
3481         public function streamStatementEnd( &$sql, &$newLine ) {
3482                 if ( $this->delimiter ) {
3483                         $prev = $newLine;
3484                         $newLine = preg_replace( '/' . preg_quote( $this->delimiter, '/' ) . '$/', '', $newLine );
3485                         if ( $newLine != $prev ) {
3486                                 return true;
3487                         }
3488                 }
3489
3490                 return false;
3491         }
3492
3493         /**
3494          * Database independent variable replacement. Replaces a set of variables
3495          * in an SQL statement with their contents as given by $this->getSchemaVars().
3496          *
3497          * Supports '{$var}' `{$var}` and / *$var* / (without the spaces) style variables.
3498          *
3499          * - '{$var}' should be used for text and is passed through the database's
3500          *   addQuotes method.
3501          * - `{$var}` should be used for identifiers (e.g. table and database names).
3502          *   It is passed through the database's addIdentifierQuotes method which
3503          *   can be overridden if the database uses something other than backticks.
3504          * - / *_* / or / *$wgDBprefix* / passes the name that follows through the
3505          *   database's tableName method.
3506          * - / *i* / passes the name that follows through the database's indexName method.
3507          * - In all other cases, / *$var* / is left unencoded. Except for table options,
3508          *   its use should be avoided. In 1.24 and older, string encoding was applied.
3509          *
3510          * @param string $ins SQL statement to replace variables in
3511          * @return string The new SQL statement with variables replaced
3512          */
3513         protected function replaceVars( $ins ) {
3514                 $vars = $this->getSchemaVars();
3515                 return preg_replace_callback(
3516                         '!
3517                                 /\* (\$wgDBprefix|[_i]) \*/ (\w*) | # 1-2. tableName, indexName
3518                                 \'\{\$ (\w+) }\'                  | # 3. addQuotes
3519                                 `\{\$ (\w+) }`                    | # 4. addIdentifierQuotes
3520                                 /\*\$ (\w+) \*/                     # 5. leave unencoded
3521                         !x',
3522                         function ( $m ) use ( $vars ) {
3523                                 // Note: Because of <https://bugs.php.net/bug.php?id=51881>,
3524                                 // check for both nonexistent keys *and* the empty string.
3525                                 if ( isset( $m[1] ) && $m[1] !== '' ) {
3526                                         if ( $m[1] === 'i' ) {
3527                                                 return $this->indexName( $m[2] );
3528                                         } else {
3529                                                 return $this->tableName( $m[2] );
3530                                         }
3531                                 } elseif ( isset( $m[3] ) && $m[3] !== '' && array_key_exists( $m[3], $vars ) ) {
3532                                         return $this->addQuotes( $vars[$m[3]] );
3533                                 } elseif ( isset( $m[4] ) && $m[4] !== '' && array_key_exists( $m[4], $vars ) ) {
3534                                         return $this->addIdentifierQuotes( $vars[$m[4]] );
3535                                 } elseif ( isset( $m[5] ) && $m[5] !== '' && array_key_exists( $m[5], $vars ) ) {
3536                                         return $vars[$m[5]];
3537                                 } else {
3538                                         return $m[0];
3539                                 }
3540                         },
3541                         $ins
3542                 );
3543         }
3544
3545         /**
3546          * Get schema variables. If none have been set via setSchemaVars(), then
3547          * use some defaults from the current object.
3548          *
3549          * @return array
3550          */
3551         protected function getSchemaVars() {
3552                 if ( $this->mSchemaVars ) {
3553                         return $this->mSchemaVars;
3554                 } else {
3555                         return $this->getDefaultSchemaVars();
3556                 }
3557         }
3558
3559         /**
3560          * Get schema variables to use if none have been set via setSchemaVars().
3561          *
3562          * Override this in derived classes to provide variables for tables.sql
3563          * and SQL patch files.
3564          *
3565          * @return array
3566          */
3567         protected function getDefaultSchemaVars() {
3568                 return [];
3569         }
3570
3571         public function lockIsFree( $lockName, $method ) {
3572                 return true;
3573         }
3574
3575         public function lock( $lockName, $method, $timeout = 5 ) {
3576                 $this->mNamedLocksHeld[$lockName] = 1;
3577
3578                 return true;
3579         }
3580
3581         public function unlock( $lockName, $method ) {
3582                 unset( $this->mNamedLocksHeld[$lockName] );
3583
3584                 return true;
3585         }
3586
3587         public function getScopedLockAndFlush( $lockKey, $fname, $timeout ) {
3588                 if ( $this->writesOrCallbacksPending() ) {
3589                         // This only flushes transactions to clear snapshots, not to write data
3590                         throw new DBUnexpectedError(
3591                                 $this,
3592                                 "$fname: Cannot COMMIT to clear snapshot because writes are pending."
3593                         );
3594                 }
3595
3596                 if ( !$this->lock( $lockKey, $fname, $timeout ) ) {
3597                         return null;
3598                 }
3599
3600                 $unlocker = new ScopedCallback( function () use ( $lockKey, $fname ) {
3601                         if ( $this->trxLevel() ) {
3602                                 // There is a good chance an exception was thrown, causing any early return
3603                                 // from the caller. Let any error handler get a chance to issue rollback().
3604                                 // If there isn't one, let the error bubble up and trigger server-side rollback.
3605                                 $this->onTransactionResolution( function () use ( $lockKey, $fname ) {
3606                                         $this->unlock( $lockKey, $fname );
3607                                 } );
3608                         } else {
3609                                 $this->unlock( $lockKey, $fname );
3610                         }
3611                 } );
3612
3613                 $this->commit( __METHOD__, self::FLUSHING_INTERNAL );
3614
3615                 return $unlocker;
3616         }
3617
3618         public function namedLocksEnqueue() {
3619                 return false;
3620         }
3621
3622         /**
3623          * Lock specific tables
3624          *
3625          * @param array $read Array of tables to lock for read access
3626          * @param array $write Array of tables to lock for write access
3627          * @param string $method Name of caller
3628          * @param bool $lowPriority Whether to indicate writes to be LOW PRIORITY
3629          * @return bool
3630          */
3631         public function lockTables( $read, $write, $method, $lowPriority = true ) {
3632                 return true;
3633         }
3634
3635         /**
3636          * Unlock specific tables
3637          *
3638          * @param string $method The caller
3639          * @return bool
3640          */
3641         public function unlockTables( $method ) {
3642                 return true;
3643         }
3644
3645         /**
3646          * Delete a table
3647          * @param string $tableName
3648          * @param string $fName
3649          * @return bool|ResultWrapper
3650          * @since 1.18
3651          */
3652         public function dropTable( $tableName, $fName = __METHOD__ ) {
3653                 if ( !$this->tableExists( $tableName, $fName ) ) {
3654                         return false;
3655                 }
3656                 $sql = "DROP TABLE " . $this->tableName( $tableName );
3657                 if ( $this->cascadingDeletes() ) {
3658                         $sql .= " CASCADE";
3659                 }
3660
3661                 return $this->query( $sql, $fName );
3662         }
3663
3664         /**
3665          * Get search engine class. All subclasses of this need to implement this
3666          * if they wish to use searching.
3667          *
3668          * @return string
3669          */
3670         public function getSearchEngine() {
3671                 return 'SearchEngineDummy';
3672         }
3673
3674         public function getInfinity() {
3675                 return 'infinity';
3676         }
3677
3678         public function encodeExpiry( $expiry ) {
3679                 return ( $expiry == '' || $expiry == 'infinity' || $expiry == $this->getInfinity() )
3680                         ? $this->getInfinity()
3681                         : $this->timestamp( $expiry );
3682         }
3683
3684         public function decodeExpiry( $expiry, $format = TS_MW ) {
3685                 return ( $expiry == '' || $expiry == 'infinity' || $expiry == $this->getInfinity() )
3686                         ? 'infinity'
3687                         : wfTimestamp( $format, $expiry );
3688         }
3689
3690         public function setBigSelects( $value = true ) {
3691                 // no-op
3692         }
3693
3694         public function isReadOnly() {
3695                 return ( $this->getReadOnlyReason() !== false );
3696         }
3697
3698         /**
3699          * @return string|bool Reason this DB is read-only or false if it is not
3700          */
3701         protected function getReadOnlyReason() {
3702                 $reason = $this->getLBInfo( 'readOnlyReason' );
3703
3704                 return is_string( $reason ) ? $reason : false;
3705         }
3706
3707         /**
3708          * @since 1.19
3709          * @return string
3710          */
3711         public function __toString() {
3712                 return (string)$this->mConn;
3713         }
3714
3715         /**
3716          * Run a few simple sanity checks
3717          */
3718         public function __destruct() {
3719                 if ( $this->mTrxLevel && $this->mTrxDoneWrites ) {
3720                         trigger_error( "Uncommitted DB writes (transaction from {$this->mTrxFname})." );
3721                 }
3722                 $danglingCallbacks = array_merge(
3723                         $this->mTrxIdleCallbacks,
3724                         $this->mTrxPreCommitCallbacks,
3725                         $this->mTrxEndCallbacks
3726                 );
3727                 if ( $danglingCallbacks ) {
3728                         $callers = [];
3729                         foreach ( $danglingCallbacks as $callbackInfo ) {
3730                                 $callers[] = $callbackInfo[1];
3731                         }
3732                         $callers = implode( ', ', $callers );
3733                         trigger_error( "DB transaction callbacks still pending (from $callers)." );
3734                 }
3735         }
3736 }
3737
3738 /**
3739  * @since 1.27
3740  */
3741 abstract class Database extends DatabaseBase {
3742         // B/C until nothing type hints for DatabaseBase
3743         // @TODO: finish renaming DatabaseBase => Database
3744 }