includes/db/Database.php

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