includes/libs/rdbms/database/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 Database implements IDatabase, LoggerAwareInterface {
  34         /** Number of times to re-try an operation in case of deadlock */
  35         const DEADLOCK_TRIES = 4;
  36         /** Minimum time to wait before retry, in microseconds */
  37         const DEADLOCK_DELAY_MIN = 500000;
  38         /** Maximum time to wait before retry */
  39         const DEADLOCK_DELAY_MAX = 1500000;
  40
  41         /** How long before it is worth doing a dummy query to test the connection */
  42         const PING_TTL = 1.0;
  43         const PING_QUERY = 'SELECT 1 AS ping';
  44
  45         const TINY_WRITE_SEC = .010;
  46         const SLOW_WRITE_SEC = .500;
  47         const SMALL_WRITE_ROWS = 100;
  48
  49         /** @var string SQL query */
  50         protected $mLastQuery = '';
  51         /** @var bool */
  52         protected $mDoneWrites = false;
  53         /** @var string|bool */
  54         protected $mPHPError = false;
  55         /** @var string */
  56         protected $mServer;
  57         /** @var string */
  58         protected $mUser;
  59         /** @var string */
  60         protected $mPassword;
  61         /** @var string */
  62         protected $mDBname;
  63         /** @var array[] $aliases Map of (table => (dbname, schema, prefix) map) */
  64         protected $tableAliases = [];
  65         /** @var bool Whether this PHP instance is for a CLI script */
  66         protected $cliMode;
  67         /** @var string Agent name for query profiling */
  68         protected $agent;
  69
  70         /** @var BagOStuff APC cache */
  71         protected $srvCache;
  72         /** @var LoggerInterface */
  73         protected $connLogger;
  74         /** @var LoggerInterface */
  75         protected $queryLogger;
  76         /** @var callback Error logging callback */
  77         protected $errorLogger;
  78
  79         /** @var resource Database connection */
  80         protected $mConn = null;
  81         /** @var bool */
  82         protected $mOpened = false;
  83
  84         /** @var array[] List of (callable, method name) */
  85         protected $mTrxIdleCallbacks = [];
  86         /** @var array[] List of (callable, method name) */
  87         protected $mTrxPreCommitCallbacks = [];
  88         /** @var array[] List of (callable, method name) */
  89         protected $mTrxEndCallbacks = [];
  90         /** @var callable[] Map of (name => callable) */
  91         protected $mTrxRecurringCallbacks = [];
  92         /** @var bool Whether to suppress triggering of transaction end callbacks */
  93         protected $mTrxEndCallbacksSuppressed = false;
  94
  95         /** @var string */
  96         protected $mTablePrefix = '';
  97         /** @var string */
  98         protected $mSchema = '';
  99         /** @var integer */
 100         protected $mFlags;
 101         /** @var array */
 102         protected $mLBInfo = [];
 103         /** @var bool|null */
 104         protected $mDefaultBigSelects = null;
 105         /** @var array|bool */
 106         protected $mSchemaVars = false;
 107         /** @var array */
 108         protected $mSessionVars = [];
 109         /** @var array|null */
 110         protected $preparedArgs;
 111         /** @var string|bool|null Stashed value of html_errors INI setting */
 112         protected $htmlErrors;
 113         /** @var string */
 114         protected $delimiter = ';';
 115         /** @var DatabaseDomain */
 116         protected $currentDomain;
 117
 118         /**
 119          * Either 1 if a transaction is active or 0 otherwise.
 120          * The other Trx fields may not be meaningfull if this is 0.
 121          *
 122          * @var int
 123          */
 124         protected $mTrxLevel = 0;
 125         /**
 126          * Either a short hexidecimal string if a transaction is active or ""
 127          *
 128          * @var string
 129          * @see DatabaseBase::mTrxLevel
 130          */
 131         protected $mTrxShortId = '';
 132         /**
 133          * The UNIX time that the transaction started. Callers can assume that if
 134          * snapshot isolation is used, then the data is *at least* up to date to that
 135          * point (possibly more up-to-date since the first SELECT defines the snapshot).
 136          *
 137          * @var float|null
 138          * @see DatabaseBase::mTrxLevel
 139          */
 140         private $mTrxTimestamp = null;
 141         /** @var float Lag estimate at the time of BEGIN */
 142         private $mTrxReplicaLag = null;
 143         /**
 144          * Remembers the function name given for starting the most recent transaction via begin().
 145          * Used to provide additional context for error reporting.
 146          *
 147          * @var string
 148          * @see DatabaseBase::mTrxLevel
 149          */
 150         private $mTrxFname = null;
 151         /**
 152          * Record if possible write queries were done in the last transaction started
 153          *
 154          * @var bool
 155          * @see DatabaseBase::mTrxLevel
 156          */
 157         private $mTrxDoneWrites = false;
 158         /**
 159          * Record if the current transaction was started implicitly due to DBO_TRX being set.
 160          *
 161          * @var bool
 162          * @see DatabaseBase::mTrxLevel
 163          */
 164         private $mTrxAutomatic = false;
 165         /**
 166          * Array of levels of atomicity within transactions
 167          *
 168          * @var array
 169          */
 170         private $mTrxAtomicLevels = [];
 171         /**
 172          * Record if the current transaction was started implicitly by DatabaseBase::startAtomic
 173          *
 174          * @var bool
 175          */
 176         private $mTrxAutomaticAtomic = false;
 177         /**
 178          * Track the write query callers of the current transaction
 179          *
 180          * @var string[]
 181          */
 182         private $mTrxWriteCallers = [];
 183         /**
 184          * @var float Seconds spent in write queries for the current transaction
 185          */
 186         private $mTrxWriteDuration = 0.0;
 187         /**
 188          * @var integer Number of write queries for the current transaction
 189          */
 190         private $mTrxWriteQueryCount = 0;
 191         /**
 192          * @var float Like mTrxWriteQueryCount but excludes lock-bound, easy to replicate, queries
 193          */
 194         private $mTrxWriteAdjDuration = 0.0;
 195         /**
 196          * @var integer Number of write queries counted in mTrxWriteAdjDuration
 197          */
 198         private $mTrxWriteAdjQueryCount = 0;
 199         /**
 200          * @var float RTT time estimate
 201          */
 202         private $mRTTEstimate = 0.0;
 203
 204         /** @var array Map of (name => 1) for locks obtained via lock() */
 205         private $mNamedLocksHeld = [];
 206
 207         /** @var IDatabase|null Lazy handle to the master DB this server replicates from */
 208         private $lazyMasterHandle;
 209
 210         /**
 211          * @since 1.21
 212          * @var resource File handle for upgrade
 213          */
 214         protected $fileHandle = null;
 215
 216         /**
 217          * @since 1.22
 218          * @var string[] Process cache of VIEWs names in the database
 219          */
 220         protected $allViews = null;
 221
 222         /** @var float UNIX timestamp */
 223         protected $lastPing = 0.0;
 224
 225         /** @var int[] Prior mFlags values */
 226         private $priorFlags = [];
 227
 228         /** @var Profiler */
 229         protected $profiler;
 230         /** @var TransactionProfiler */
 231         protected $trxProfiler;
 232
 233         /**
 234          * Constructor.
 235          *
 236          * FIXME: It is possible to construct a Database object with no associated
 237          * connection object, by specifying no parameters to __construct(). This
 238          * feature is deprecated and should be removed.
 239          *
 240          * IDatabase classes should not be constructed directly in external
 241          * code. DatabaseBase::factory() should be used instead.
 242          *
 243          * @param array $params Parameters passed from DatabaseBase::factory()
 244          */
 245         function __construct( array $params ) {
 246                 $server = $params['host'];
 247                 $user = $params['user'];
 248                 $password = $params['password'];
 249                 $dbName = $params['dbname'];
 250                 $flags = $params['flags'];
 251
 252                 $this->mSchema = $params['schema'];
 253                 $this->mTablePrefix = $params['tablePrefix'];
 254
 255                 $this->cliMode = isset( $params['cliMode'] )
 256                         ? $params['cliMode']
 257                         : ( PHP_SAPI === 'cli' );
 258                 $this->agent = isset( $params['agent'] )
 259                         ? str_replace( '/', '-', $params['agent'] ) // escape for comment
 260                         : '';
 261
 262                 $this->mFlags = $flags;
 263                 if ( $this->mFlags & DBO_DEFAULT ) {
 264                         if ( $this->cliMode ) {
 265                                 $this->mFlags &= ~DBO_TRX;
 266                         } else {
 267                                 $this->mFlags |= DBO_TRX;
 268                         }
 269                 }
 270
 271                 $this->mSessionVars = $params['variables'];
 272
 273                 $this->srvCache = isset( $params['srvCache'] )
 274                         ? $params['srvCache']
 275                         : new HashBagOStuff();
 276
 277                 $this->profiler = isset( $params['profiler'] )
 278                         ? $params['profiler']
 279                         : Profiler::instance(); // @TODO: remove global state
 280                 $this->trxProfiler = isset( $params['trxProfiler'] )
 281                         ? $params['trxProfiler']
 282                         : new TransactionProfiler();
 283                 $this->connLogger = isset( $params['connLogger'] )
 284                         ? $params['connLogger']
 285                         : new \Psr\Log\NullLogger();
 286                 $this->queryLogger = isset( $params['queryLogger'] )
 287                         ? $params['queryLogger']
 288                         : new \Psr\Log\NullLogger();
 289
 290                 if ( $user ) {
 291                         $this->open( $server, $user, $password, $dbName );
 292                 }
 293
 294                 $this->currentDomain = ( $this->mDBname != '' )
 295                         ? new DatabaseDomain( $this->mDBname, null, $this->mTablePrefix )
 296                         : DatabaseDomain::newUnspecified();
 297         }
 298
 299         /**
 300          * Given a DB type, construct the name of the appropriate child class of
 301          * IDatabase. This is designed to replace all of the manual stuff like:
 302          *    $class = 'Database' . ucfirst( strtolower( $dbType ) );
 303          * as well as validate against the canonical list of DB types we have
 304          *
 305          * This factory function is mostly useful for when you need to connect to a
 306          * database other than the MediaWiki default (such as for external auth,
 307          * an extension, et cetera). Do not use this to connect to the MediaWiki
 308          * database. Example uses in core:
 309          * @see LoadBalancer::reallyOpenConnection()
 310          * @see ForeignDBRepo::getMasterDB()
 311          * @see WebInstallerDBConnect::execute()
 312          *
 313          * @since 1.18
 314          *
 315          * @param string $dbType A possible DB type
 316          * @param array $p An array of options to pass to the constructor.
 317          *    Valid options are: host, user, password, dbname, flags, tablePrefix, schema, driver
 318          * @return IDatabase|null If the database driver or extension cannot be found
 319          * @throws InvalidArgumentException If the database driver or extension cannot be found
 320          */
 321         final public static function factory( $dbType, $p = [] ) {
 322                 $canonicalDBTypes = [
 323                         'mysql' => [ 'mysqli', 'mysql' ],
 324                         'postgres' => [],
 325                         'sqlite' => [],
 326                         'oracle' => [],
 327                         'mssql' => [],
 328                 ];
 329
 330                 $driver = false;
 331                 $dbType = strtolower( $dbType );
 332                 if ( isset( $canonicalDBTypes[$dbType] ) && $canonicalDBTypes[$dbType] ) {
 333                         $possibleDrivers = $canonicalDBTypes[$dbType];
 334                         if ( !empty( $p['driver'] ) ) {
 335                                 if ( in_array( $p['driver'], $possibleDrivers ) ) {
 336                                         $driver = $p['driver'];
 337                                 } else {
 338                                         throw new InvalidArgumentException( __METHOD__ .
 339                                                 " type '$dbType' does not support driver '{$p['driver']}'" );
 340                                 }
 341                         } else {
 342                                 foreach ( $possibleDrivers as $posDriver ) {
 343                                         if ( extension_loaded( $posDriver ) ) {
 344                                                 $driver = $posDriver;
 345                                                 break;
 346                                         }
 347                                 }
 348                         }
 349                 } else {
 350                         $driver = $dbType;
 351                 }
 352                 if ( $driver === false ) {
 353                         throw new InvalidArgumentException( __METHOD__ .
 354                                 " no viable database extension found for type '$dbType'" );
 355                 }
 356
 357                 // Determine schema defaults. Currently Microsoft SQL Server uses $wgDBmwschema,
 358                 // and everything else doesn't use a schema (e.g. null)
 359                 // Although postgres and oracle support schemas, we don't use them (yet)
 360                 // to maintain backwards compatibility
 361                 $defaultSchemas = [
 362                         'mssql' => 'get from global',
 363                 ];
 364
 365                 $class = 'Database' . ucfirst( $driver );
 366                 if ( class_exists( $class ) && is_subclass_of( $class, 'IDatabase' ) ) {
 367                         // Resolve some defaults for b/c
 368                         $p['host'] = isset( $p['host'] ) ? $p['host'] : false;
 369                         $p['user'] = isset( $p['user'] ) ? $p['user'] : false;
 370                         $p['password'] = isset( $p['password'] ) ? $p['password'] : false;
 371                         $p['dbname'] = isset( $p['dbname'] ) ? $p['dbname'] : false;
 372                         $p['flags'] = isset( $p['flags'] ) ? $p['flags'] : 0;
 373                         $p['variables'] = isset( $p['variables'] ) ? $p['variables'] : [];
 374                         $p['tablePrefix'] = isset( $p['tablePrefix'] ) ? $p['tablePrefix'] : '';
 375                         if ( !isset( $p['schema'] ) ) {
 376                                 $p['schema'] = isset( $defaultSchemas[$dbType] ) ? $defaultSchemas[$dbType] : '';
 377                         }
 378                         $p['foreign'] = isset( $p['foreign'] ) ? $p['foreign'] : false;
 379
 380                         $conn = new $class( $p );
 381                         if ( isset( $p['connLogger'] ) ) {
 382                                 $conn->connLogger = $p['connLogger'];
 383                         }
 384                         if ( isset( $p['queryLogger'] ) ) {
 385                                 $conn->queryLogger = $p['queryLogger'];
 386                         }
 387                         if ( isset( $p['errorLogger'] ) ) {
 388                                 $conn->errorLogger = $p['errorLogger'];
 389                         } else {
 390                                 $conn->errorLogger = function ( Exception $e ) {
 391                                         trigger_error( get_class( $e ) . ': ' . $e->getMessage(), E_WARNING );
 392                                 };
 393                         }
 394                 } else {
 395                         $conn = null;
 396                 }
 397
 398                 return $conn;
 399         }
 400
 401         public function setLogger( LoggerInterface $logger ) {
 402                 $this->queryLogger = $logger;
 403         }
 404
 405         public function getServerInfo() {
 406                 return $this->getServerVersion();
 407         }
 408
 409         public function bufferResults( $buffer = null ) {
 410                 $res = !$this->getFlag( DBO_NOBUFFER );
 411                 if ( $buffer !== null ) {
 412                         $buffer ? $this->clearFlag( DBO_NOBUFFER ) : $this->setFlag( DBO_NOBUFFER );
 413                 }
 414
 415                 return $res;
 416         }
 417
 418         /**
 419          * Turns on (false) or off (true) the automatic generation and sending
 420          * of a "we're sorry, but there has been a database error" page on
 421          * database errors. Default is on (false). When turned off, the
 422          * code should use lastErrno() and lastError() to handle the
 423          * situation as appropriate.
 424          *
 425          * Do not use this function outside of the Database classes.
 426          *
 427          * @param null|bool $ignoreErrors
 428          * @return bool The previous value of the flag.
 429          */
 430         protected function ignoreErrors( $ignoreErrors = null ) {
 431                 $res = $this->getFlag( DBO_IGNORE );
 432                 if ( $ignoreErrors !== null ) {
 433                         $ignoreErrors ? $this->setFlag( DBO_IGNORE ) : $this->clearFlag( DBO_IGNORE );
 434                 }
 435
 436                 return $res;
 437         }
 438
 439         public function trxLevel() {
 440                 return $this->mTrxLevel;
 441         }
 442
 443         public function trxTimestamp() {
 444                 return $this->mTrxLevel ? $this->mTrxTimestamp : null;
 445         }
 446
 447         public function tablePrefix( $prefix = null ) {
 448                 $old = $this->mTablePrefix;
 449                 if ( $prefix !== null ) {
 450                         $this->mTablePrefix = $prefix;
 451                         $this->currentDomain = ( $this->mDBname != '' )
 452                                 ? new DatabaseDomain( $this->mDBname, null, $this->mTablePrefix )
 453                                 : DatabaseDomain::newUnspecified();
 454                 }
 455
 456                 return $old;
 457         }
 458
 459         public function dbSchema( $schema = null ) {
 460                 $old = $this->mSchema;
 461                 if ( $schema !== null ) {
 462                         $this->mSchema = $schema;
 463                 }
 464
 465                 return $old;
 466         }
 467
 468         /**
 469          * Set the filehandle to copy write statements to.
 470          *
 471          * @param resource $fh File handle
 472          */
 473         public function setFileHandle( $fh ) {
 474                 $this->fileHandle = $fh;
 475         }
 476
 477         public function getLBInfo( $name = null ) {
 478                 if ( is_null( $name ) ) {
 479                         return $this->mLBInfo;
 480                 } else {
 481                         if ( array_key_exists( $name, $this->mLBInfo ) ) {
 482                                 return $this->mLBInfo[$name];
 483                         } else {
 484                                 return null;
 485                         }
 486                 }
 487         }
 488
 489         public function setLBInfo( $name, $value = null ) {
 490                 if ( is_null( $value ) ) {
 491                         $this->mLBInfo = $name;
 492                 } else {
 493                         $this->mLBInfo[$name] = $value;
 494                 }
 495         }
 496
 497         public function setLazyMasterHandle( IDatabase $conn ) {
 498                 $this->lazyMasterHandle = $conn;
 499         }
 500
 501         /**
 502          * @return IDatabase|null
 503          * @see setLazyMasterHandle()
 504          * @since 1.27
 505          */
 506         public function getLazyMasterHandle() {
 507                 return $this->lazyMasterHandle;
 508         }
 509
 510         /**
 511          * @param TransactionProfiler $profiler
 512          * @since 1.27
 513          */
 514         public function setTransactionProfiler( TransactionProfiler $profiler ) {
 515                 $this->trxProfiler = $profiler;
 516         }
 517
 518         public function implicitGroupby() {
 519                 return true;
 520         }
 521
 522         public function implicitOrderby() {
 523                 return true;
 524         }
 525
 526         public function lastQuery() {
 527                 return $this->mLastQuery;
 528         }
 529
 530         public function doneWrites() {
 531                 return (bool)$this->mDoneWrites;
 532         }
 533
 534         public function lastDoneWrites() {
 535                 return $this->mDoneWrites ?: false;
 536         }
 537
 538         public function writesPending() {
 539                 return $this->mTrxLevel && $this->mTrxDoneWrites;
 540         }
 541
 542         public function writesOrCallbacksPending() {
 543                 return $this->mTrxLevel && (
 544                         $this->mTrxDoneWrites || $this->mTrxIdleCallbacks || $this->mTrxPreCommitCallbacks
 545                 );
 546         }
 547
 548         public function pendingWriteQueryDuration( $type = self::ESTIMATE_TOTAL ) {
 549                 if ( !$this->mTrxLevel ) {
 550                         return false;
 551                 } elseif ( !$this->mTrxDoneWrites ) {
 552                         return 0.0;
 553                 }
 554
 555                 switch ( $type ) {
 556                         case self::ESTIMATE_DB_APPLY:
 557                                 $this->ping( $rtt );
 558                                 $rttAdjTotal = $this->mTrxWriteAdjQueryCount * $rtt;
 559                                 $applyTime = max( $this->mTrxWriteAdjDuration - $rttAdjTotal, 0 );
 560                                 // For omitted queries, make them count as something at least
 561                                 $omitted = $this->mTrxWriteQueryCount - $this->mTrxWriteAdjQueryCount;
 562                                 $applyTime += self::TINY_WRITE_SEC * $omitted;
 563
 564                                 return $applyTime;
 565                         default: // everything
 566                                 return $this->mTrxWriteDuration;
 567                 }
 568         }
 569
 570         public function pendingWriteCallers() {
 571                 return $this->mTrxLevel ? $this->mTrxWriteCallers : [];
 572         }
 573
 574         protected function pendingWriteAndCallbackCallers() {
 575                 if ( !$this->mTrxLevel ) {
 576                         return [];
 577                 }
 578
 579                 $fnames = $this->mTrxWriteCallers;
 580                 foreach ( [
 581                         $this->mTrxIdleCallbacks,
 582                         $this->mTrxPreCommitCallbacks,
 583                         $this->mTrxEndCallbacks
 584                 ] as $callbacks ) {
 585                         foreach ( $callbacks as $callback ) {
 586                                 $fnames[] = $callback[1];
 587                         }
 588                 }
 589
 590                 return $fnames;
 591         }
 592
 593         public function isOpen() {
 594                 return $this->mOpened;
 595         }
 596
 597         public function setFlag( $flag, $remember = self::REMEMBER_NOTHING ) {
 598                 if ( $remember === self::REMEMBER_PRIOR ) {
 599                         array_push( $this->priorFlags, $this->mFlags );
 600                 }
 601                 $this->mFlags |= $flag;
 602         }
 603
 604         public function clearFlag( $flag, $remember = self::REMEMBER_NOTHING ) {
 605                 if ( $remember === self::REMEMBER_PRIOR ) {
 606                         array_push( $this->priorFlags, $this->mFlags );
 607                 }
 608                 $this->mFlags &= ~$flag;
 609         }
 610
 611         public function restoreFlags( $state = self::RESTORE_PRIOR ) {
 612                 if ( !$this->priorFlags ) {
 613                         return;
 614                 }
 615
 616                 if ( $state === self::RESTORE_INITIAL ) {
 617                         $this->mFlags = reset( $this->priorFlags );
 618                         $this->priorFlags = [];
 619                 } else {
 620                         $this->mFlags = array_pop( $this->priorFlags );
 621                 }
 622         }
 623
 624         public function getFlag( $flag ) {
 625                 return !!( $this->mFlags & $flag );
 626         }
 627
 628         public function getProperty( $name ) {
 629                 return $this->$name;
 630         }
 631
 632         public function getDomainID() {
 633                 return $this->currentDomain->getId();
 634         }
 635
 636         final public function getWikiID() {
 637                 return $this->getDomainID();
 638         }
 639
 640         /**
 641          * Get information about an index into an object
 642          * @param string $table Table name
 643          * @param string $index Index name
 644          * @param string $fname Calling function name
 645          * @return mixed Database-specific index description class or false if the index does not exist
 646          */
 647         abstract function indexInfo( $table, $index, $fname = __METHOD__ );
 648
 649         /**
 650          * Wrapper for addslashes()
 651          *
 652          * @param string $s String to be slashed.
 653          * @return string Slashed string.
 654          */
 655         abstract function strencode( $s );
 656
 657         protected function installErrorHandler() {
 658                 $this->mPHPError = false;
 659                 $this->htmlErrors = ini_set( 'html_errors', '0' );
 660                 set_error_handler( [ $this, 'connectionerrorLogger' ] );
 661         }
 662
 663         /**
 664          * @return bool|string
 665          */
 666         protected function restoreErrorHandler() {
 667                 restore_error_handler();
 668                 if ( $this->htmlErrors !== false ) {
 669                         ini_set( 'html_errors', $this->htmlErrors );
 670                 }
 671                 if ( $this->mPHPError ) {
 672                         $error = preg_replace( '!\[<a.*</a>\]!', '', $this->mPHPError );
 673                         $error = preg_replace( '!^.*?:\s?(.*)$!', '$1', $error );
 674
 675                         return $error;
 676                 } else {
 677                         return false;
 678                 }
 679         }
 680
 681         /**
 682          * @param int $errno
 683          * @param string $errstr
 684          */
 685         public function connectionerrorLogger( $errno, $errstr ) {
 686                 $this->mPHPError = $errstr;
 687         }
 688
 689         /**
 690          * Create a log context to pass to PSR logging functions.
 691          *
 692          * @param array $extras Additional data to add to context
 693          * @return array
 694          */
 695         protected function getLogContext( array $extras = [] ) {
 696                 return array_merge(
 697                         [
 698                                 'db_server' => $this->mServer,
 699                                 'db_name' => $this->mDBname,
 700                                 'db_user' => $this->mUser,
 701                         ],
 702                         $extras
 703                 );
 704         }
 705
 706         public function close() {
 707                 if ( $this->mConn ) {
 708                         if ( $this->trxLevel() ) {
 709                                 $this->commit( __METHOD__, self::FLUSHING_INTERNAL );
 710                         }
 711
 712                         $closed = $this->closeConnection();
 713                         $this->mConn = false;
 714                 } elseif ( $this->mTrxIdleCallbacks || $this->mTrxEndCallbacks ) { // sanity
 715                         throw new RuntimeException( "Transaction callbacks still pending." );
 716                 } else {
 717                         $closed = true;
 718                 }
 719                 $this->mOpened = false;
 720
 721                 return $closed;
 722         }
 723
 724         /**
 725          * Make sure isOpen() returns true as a sanity check
 726          *
 727          * @throws DBUnexpectedError
 728          */
 729         protected function assertOpen() {
 730                 if ( !$this->isOpen() ) {
 731                         throw new DBUnexpectedError( $this, "DB connection was already closed." );
 732                 }
 733         }
 734
 735         /**
 736          * Closes underlying database connection
 737          * @since 1.20
 738          * @return bool Whether connection was closed successfully
 739          */
 740         abstract protected function closeConnection();
 741
 742         function reportConnectionError( $error = 'Unknown error' ) {
 743                 $myError = $this->lastError();
 744                 if ( $myError ) {
 745                         $error = $myError;
 746                 }
 747
 748                 # New method
 749                 throw new DBConnectionError( $this, $error );
 750         }
 751
 752         /**
 753          * The DBMS-dependent part of query()
 754          *
 755          * @param string $sql SQL query.
 756          * @return ResultWrapper|bool Result object to feed to fetchObject,
 757          *   fetchRow, ...; or false on failure
 758          */
 759         abstract protected function doQuery( $sql );
 760
 761         /**
 762          * Determine whether a query writes to the DB.
 763          * Should return true if unsure.
 764          *
 765          * @param string $sql
 766          * @return bool
 767          */
 768         protected function isWriteQuery( $sql ) {
 769                 return !preg_match(
 770                         '/^(?:SELECT|BEGIN|ROLLBACK|COMMIT|SET|SHOW|EXPLAIN|\(SELECT)\b/i', $sql );
 771         }
 772
 773         /**
 774          * @param $sql
 775          * @return string|null
 776          */
 777         protected function getQueryVerb( $sql ) {
 778                 return preg_match( '/^\s*([a-z]+)/i', $sql, $m ) ? strtoupper( $m[1] ) : null;
 779         }
 780
 781         /**
 782          * Determine whether a SQL statement is sensitive to isolation level.
 783          * A SQL statement is considered transactable if its result could vary
 784          * depending on the transaction isolation level. Operational commands
 785          * such as 'SET' and 'SHOW' are not considered to be transactable.
 786          *
 787          * @param string $sql
 788          * @return bool
 789          */
 790         protected function isTransactableQuery( $sql ) {
 791                 $verb = $this->getQueryVerb( $sql );
 792                 return !in_array( $verb, [ 'BEGIN', 'COMMIT', 'ROLLBACK', 'SHOW', 'SET' ], true );
 793         }
 794
 795         public function query( $sql, $fname = __METHOD__, $tempIgnore = false ) {
 796                 $priorWritesPending = $this->writesOrCallbacksPending();
 797                 $this->mLastQuery = $sql;
 798
 799                 $isWrite = $this->isWriteQuery( $sql );
 800                 if ( $isWrite ) {
 801                         $reason = $this->getReadOnlyReason();
 802                         if ( $reason !== false ) {
 803                                 throw new DBReadOnlyError( $this, "Database is read-only: $reason" );
 804                         }
 805                         # Set a flag indicating that writes have been done
 806                         $this->mDoneWrites = microtime( true );
 807                 }
 808
 809                 // Add trace comment to the begin of the sql string, right after the operator.
 810                 // Or, for one-word queries (like "BEGIN" or COMMIT") add it to the end (bug 42598)
 811                 $commentedSql = preg_replace( '/\s|$/', " /* $fname {$this->agent} */ ", $sql, 1 );
 812
 813                 # Start implicit transactions that wrap the request if DBO_TRX is enabled
 814                 if ( !$this->mTrxLevel && $this->getFlag( DBO_TRX )
 815                         && $this->isTransactableQuery( $sql )
 816                 ) {
 817                         $this->begin( __METHOD__ . " ($fname)", self::TRANSACTION_INTERNAL );
 818                         $this->mTrxAutomatic = true;
 819                 }
 820
 821                 # Keep track of whether the transaction has write queries pending
 822                 if ( $this->mTrxLevel && !$this->mTrxDoneWrites && $isWrite ) {
 823                         $this->mTrxDoneWrites = true;
 824                         $this->trxProfiler->transactionWritingIn(
 825                                 $this->mServer, $this->mDBname, $this->mTrxShortId );
 826                 }
 827
 828                 if ( $this->getFlag( DBO_DEBUG ) ) {
 829                         $this->queryLogger->debug( "{$this->mDBname} {$commentedSql}" );
 830                 }
 831
 832                 # Avoid fatals if close() was called
 833                 $this->assertOpen();
 834
 835                 # Send the query to the server
 836                 $ret = $this->doProfiledQuery( $sql, $commentedSql, $isWrite, $fname );
 837
 838                 # Try reconnecting if the connection was lost
 839                 if ( false === $ret && $this->wasErrorReissuable() ) {
 840                         $recoverable = $this->canRecoverFromDisconnect( $sql, $priorWritesPending );
 841                         # Stash the last error values before anything might clear them
 842                         $lastError = $this->lastError();
 843                         $lastErrno = $this->lastErrno();
 844                         # Update state tracking to reflect transaction loss due to disconnection
 845                         $this->handleTransactionLoss();
 846                         if ( $this->reconnect() ) {
 847                                 $msg = __METHOD__ . ": lost connection to {$this->getServer()}; reconnected";
 848                                 $this->connLogger->warning( $msg );
 849                                 $this->queryLogger->warning(
 850                                         "$msg:\n" . ( new RuntimeException() )->getTraceAsString() );
 851
 852                                 if ( !$recoverable ) {
 853                                         # Callers may catch the exception and continue to use the DB
 854                                         $this->reportQueryError( $lastError, $lastErrno, $sql, $fname );
 855                                 } else {
 856                                         # Should be safe to silently retry the query
 857                                         $ret = $this->doProfiledQuery( $sql, $commentedSql, $isWrite, $fname );
 858                                 }
 859                         } else {
 860                                 $msg = __METHOD__ . ": lost connection to {$this->getServer()} permanently";
 861                                 $this->connLogger->error( $msg );
 862                         }
 863                 }
 864
 865                 if ( false === $ret ) {
 866                         # Deadlocks cause the entire transaction to abort, not just the statement.
 867                         # http://dev.mysql.com/doc/refman/5.7/en/innodb-error-handling.html
 868                         # https://www.postgresql.org/docs/9.1/static/explicit-locking.html
 869                         if ( $this->wasDeadlock() ) {
 870                                 if ( $this->explicitTrxActive() || $priorWritesPending ) {
 871                                         $tempIgnore = false; // not recoverable
 872                                 }
 873                                 # Update state tracking to reflect transaction loss
 874                                 $this->handleTransactionLoss();
 875                         }
 876
 877                         $this->reportQueryError(
 878                                 $this->lastError(), $this->lastErrno(), $sql, $fname, $tempIgnore );
 879                 }
 880
 881                 $res = $this->resultObject( $ret );
 882
 883                 return $res;
 884         }
 885
 886         private function doProfiledQuery( $sql, $commentedSql, $isWrite, $fname ) {
 887                 $isMaster = !is_null( $this->getLBInfo( 'master' ) );
 888                 # generalizeSQL() will probably cut down the query to reasonable
 889                 # logging size most of the time. The substr is really just a sanity check.
 890                 if ( $isMaster ) {
 891                         $queryProf = 'query-m: ' . substr( self::generalizeSQL( $sql ), 0, 255 );
 892                 } else {
 893                         $queryProf = 'query: ' . substr( self::generalizeSQL( $sql ), 0, 255 );
 894                 }
 895
 896                 # Include query transaction state
 897                 $queryProf .= $this->mTrxShortId ? " [TRX#{$this->mTrxShortId}]" : "";
 898
 899                 $startTime = microtime( true );
 900                 $this->profiler->profileIn( $queryProf );
 901                 $ret = $this->doQuery( $commentedSql );
 902                 $this->profiler->profileOut( $queryProf );
 903                 $queryRuntime = max( microtime( true ) - $startTime, 0.0 );
 904
 905                 unset( $queryProfSection ); // profile out (if set)
 906
 907                 if ( $ret !== false ) {
 908                         $this->lastPing = $startTime;
 909                         if ( $isWrite && $this->mTrxLevel ) {
 910                                 $this->updateTrxWriteQueryTime( $sql, $queryRuntime );
 911                                 $this->mTrxWriteCallers[] = $fname;
 912                         }
 913                 }
 914
 915                 if ( $sql === self::PING_QUERY ) {
 916                         $this->mRTTEstimate = $queryRuntime;
 917                 }
 918
 919                 $this->trxProfiler->recordQueryCompletion(
 920                         $queryProf, $startTime, $isWrite, $this->affectedRows()
 921                 );
 922                 MWDebug::query( $sql, $fname, $isMaster, $queryRuntime );
 923
 924                 return $ret;
 925         }
 926
 927         /**
 928          * Update the estimated run-time of a query, not counting large row lock times
 929          *
 930          * LoadBalancer can be set to rollback transactions that will create huge replication
 931          * lag. It bases this estimate off of pendingWriteQueryDuration(). Certain simple
 932          * queries, like inserting a row can take a long time due to row locking. This method
 933          * uses some simple heuristics to discount those cases.
 934          *
 935          * @param string $sql A SQL write query
 936          * @param float $runtime Total runtime, including RTT
 937          */
 938         private function updateTrxWriteQueryTime( $sql, $runtime ) {
 939                 // Whether this is indicative of replica DB runtime (except for RBR or ws_repl)
 940                 $indicativeOfReplicaRuntime = true;
 941                 if ( $runtime > self::SLOW_WRITE_SEC ) {
 942                         $verb = $this->getQueryVerb( $sql );
 943                         // insert(), upsert(), replace() are fast unless bulky in size or blocked on locks
 944                         if ( $verb === 'INSERT' ) {
 945                                 $indicativeOfReplicaRuntime = $this->affectedRows() > self::SMALL_WRITE_ROWS;
 946                         } elseif ( $verb === 'REPLACE' ) {
 947                                 $indicativeOfReplicaRuntime = $this->affectedRows() > self::SMALL_WRITE_ROWS / 2;
 948                         }
 949                 }
 950
 951                 $this->mTrxWriteDuration += $runtime;
 952                 $this->mTrxWriteQueryCount += 1;
 953                 if ( $indicativeOfReplicaRuntime ) {
 954                         $this->mTrxWriteAdjDuration += $runtime;
 955                         $this->mTrxWriteAdjQueryCount += 1;
 956                 }
 957         }
 958
 959         private function canRecoverFromDisconnect( $sql, $priorWritesPending ) {
 960                 # Transaction dropped; this can mean lost writes, or REPEATABLE-READ snapshots.
 961                 # Dropped connections also mean that named locks are automatically released.
 962                 # Only allow error suppression in autocommit mode or when the lost transaction
 963                 # didn't matter anyway (aside from DBO_TRX snapshot loss).
 964                 if ( $this->mNamedLocksHeld ) {
 965                         return false; // possible critical section violation
 966                 } elseif ( $sql === 'COMMIT' ) {
 967                         return !$priorWritesPending; // nothing written anyway? (T127428)
 968                 } elseif ( $sql === 'ROLLBACK' ) {
 969                         return true; // transaction lost...which is also what was requested :)
 970                 } elseif ( $this->explicitTrxActive() ) {
 971                         return false; // don't drop atomocity
 972                 } elseif ( $priorWritesPending ) {
 973                         return false; // prior writes lost from implicit transaction
 974                 }
 975
 976                 return true;
 977         }
 978
 979         private function handleTransactionLoss() {
 980                 $this->mTrxLevel = 0;
 981                 $this->mTrxIdleCallbacks = []; // bug 65263
 982                 $this->mTrxPreCommitCallbacks = []; // bug 65263
 983                 try {
 984                         // Handle callbacks in mTrxEndCallbacks
 985                         $this->runOnTransactionIdleCallbacks( self::TRIGGER_ROLLBACK );
 986                         $this->runTransactionListenerCallbacks( self::TRIGGER_ROLLBACK );
 987                         return null;
 988                 } catch ( Exception $e ) {
 989                         // Already logged; move on...
 990                         return $e;
 991                 }
 992         }
 993
 994         public function reportQueryError( $error, $errno, $sql, $fname, $tempIgnore = false ) {
 995                 if ( $this->ignoreErrors() || $tempIgnore ) {
 996                         $this->queryLogger->debug( "SQL ERROR (ignored): $error\n" );
 997                 } else {
 998                         $sql1line = mb_substr( str_replace( "\n", "\\n", $sql ), 0, 5 * 1024 );
 999                         $this->queryLogger->error(
1000                                 "{fname}\t{db_server}\t{errno}\t{error}\t{sql1line}",
1001                                 $this->getLogContext( [
1002                                         'method' => __METHOD__,
1003                                         'errno' => $errno,
1004                                         'error' => $error,
1005                                         'sql1line' => $sql1line,
1006                                         'fname' => $fname,
1007                                 ] )
1008                         );
1009                         $this->queryLogger->debug( "SQL ERROR: " . $error . "\n" );
1010                         throw new DBQueryError( $this, $error, $errno, $sql, $fname );
1011                 }
1012         }
1013
1014         public function freeResult( $res ) {
1015         }
1016
1017         public function selectField(
1018                 $table, $var, $cond = '', $fname = __METHOD__, $options = []
1019         ) {
1020                 if ( $var === '*' ) { // sanity
1021                         throw new DBUnexpectedError( $this, "Cannot use a * field: got '$var'" );
1022                 }
1023
1024                 if ( !is_array( $options ) ) {
1025                         $options = [ $options ];
1026                 }
1027
1028                 $options['LIMIT'] = 1;
1029
1030                 $res = $this->select( $table, $var, $cond, $fname, $options );
1031                 if ( $res === false || !$this->numRows( $res ) ) {
1032                         return false;
1033                 }
1034
1035                 $row = $this->fetchRow( $res );
1036
1037                 if ( $row !== false ) {
1038                         return reset( $row );
1039                 } else {
1040                         return false;
1041                 }
1042         }
1043
1044         public function selectFieldValues(
1045                 $table, $var, $cond = '', $fname = __METHOD__, $options = [], $join_conds = []
1046         ) {
1047                 if ( $var === '*' ) { // sanity
1048                         throw new DBUnexpectedError( $this, "Cannot use a * field" );
1049                 } elseif ( !is_string( $var ) ) { // sanity
1050                         throw new DBUnexpectedError( $this, "Cannot use an array of fields" );
1051                 }
1052
1053                 if ( !is_array( $options ) ) {
1054                         $options = [ $options ];
1055                 }
1056
1057                 $res = $this->select( $table, $var, $cond, $fname, $options, $join_conds );
1058                 if ( $res === false ) {
1059                         return false;
1060                 }
1061
1062                 $values = [];
1063                 foreach ( $res as $row ) {
1064                         $values[] = $row->$var;
1065                 }
1066
1067                 return $values;
1068         }
1069
1070         /**
1071          * Returns an optional USE INDEX clause to go after the table, and a
1072          * string to go at the end of the query.
1073          *
1074          * @param array $options Associative array of options to be turned into
1075          *   an SQL query, valid keys are listed in the function.
1076          * @return array
1077          * @see DatabaseBase::select()
1078          */
1079         public function makeSelectOptions( $options ) {
1080                 $preLimitTail = $postLimitTail = '';
1081                 $startOpts = '';
1082
1083                 $noKeyOptions = [];
1084
1085                 foreach ( $options as $key => $option ) {
1086                         if ( is_numeric( $key ) ) {
1087                                 $noKeyOptions[$option] = true;
1088                         }
1089                 }
1090
1091                 $preLimitTail .= $this->makeGroupByWithHaving( $options );
1092
1093                 $preLimitTail .= $this->makeOrderBy( $options );
1094
1095                 // if (isset($options['LIMIT'])) {
1096                 //      $tailOpts .= $this->limitResult('', $options['LIMIT'],
1097                 //              isset($options['OFFSET']) ? $options['OFFSET']
1098                 //              : false);
1099                 // }
1100
1101                 if ( isset( $noKeyOptions['FOR UPDATE'] ) ) {
1102                         $postLimitTail .= ' FOR UPDATE';
1103                 }
1104
1105                 if ( isset( $noKeyOptions['LOCK IN SHARE MODE'] ) ) {
1106                         $postLimitTail .= ' LOCK IN SHARE MODE';
1107                 }
1108
1109                 if ( isset( $noKeyOptions['DISTINCT'] ) || isset( $noKeyOptions['DISTINCTROW'] ) ) {
1110                         $startOpts .= 'DISTINCT';
1111                 }
1112
1113                 # Various MySQL extensions
1114                 if ( isset( $noKeyOptions['STRAIGHT_JOIN'] ) ) {
1115                         $startOpts .= ' /*! STRAIGHT_JOIN */';
1116                 }
1117
1118                 if ( isset( $noKeyOptions['HIGH_PRIORITY'] ) ) {
1119                         $startOpts .= ' HIGH_PRIORITY';
1120                 }
1121
1122                 if ( isset( $noKeyOptions['SQL_BIG_RESULT'] ) ) {
1123                         $startOpts .= ' SQL_BIG_RESULT';
1124                 }
1125
1126                 if ( isset( $noKeyOptions['SQL_BUFFER_RESULT'] ) ) {
1127                         $startOpts .= ' SQL_BUFFER_RESULT';
1128                 }
1129
1130                 if ( isset( $noKeyOptions['SQL_SMALL_RESULT'] ) ) {
1131                         $startOpts .= ' SQL_SMALL_RESULT';
1132                 }
1133
1134                 if ( isset( $noKeyOptions['SQL_CALC_FOUND_ROWS'] ) ) {
1135                         $startOpts .= ' SQL_CALC_FOUND_ROWS';
1136                 }
1137
1138                 if ( isset( $noKeyOptions['SQL_CACHE'] ) ) {
1139                         $startOpts .= ' SQL_CACHE';
1140                 }
1141
1142                 if ( isset( $noKeyOptions['SQL_NO_CACHE'] ) ) {
1143                         $startOpts .= ' SQL_NO_CACHE';
1144                 }
1145
1146                 if ( isset( $options['USE INDEX'] ) && is_string( $options['USE INDEX'] ) ) {
1147                         $useIndex = $this->useIndexClause( $options['USE INDEX'] );
1148                 } else {
1149                         $useIndex = '';
1150                 }
1151                 if ( isset( $options['IGNORE INDEX'] ) && is_string( $options['IGNORE INDEX'] ) ) {
1152                         $ignoreIndex = $this->ignoreIndexClause( $options['IGNORE INDEX'] );
1153                 } else {
1154                         $ignoreIndex = '';
1155                 }
1156
1157                 return [ $startOpts, $useIndex, $preLimitTail, $postLimitTail, $ignoreIndex ];
1158         }
1159
1160         /**
1161          * Returns an optional GROUP BY with an optional HAVING
1162          *
1163          * @param array $options Associative array of options
1164          * @return string
1165          * @see DatabaseBase::select()
1166          * @since 1.21
1167          */
1168         public function makeGroupByWithHaving( $options ) {
1169                 $sql = '';
1170                 if ( isset( $options['GROUP BY'] ) ) {
1171                         $gb = is_array( $options['GROUP BY'] )
1172                                 ? implode( ',', $options['GROUP BY'] )
1173                                 : $options['GROUP BY'];
1174                         $sql .= ' GROUP BY ' . $gb;
1175                 }
1176                 if ( isset( $options['HAVING'] ) ) {
1177                         $having = is_array( $options['HAVING'] )
1178                                 ? $this->makeList( $options['HAVING'], LIST_AND )
1179                                 : $options['HAVING'];
1180                         $sql .= ' HAVING ' . $having;
1181                 }
1182
1183                 return $sql;
1184         }
1185
1186         /**
1187          * Returns an optional ORDER BY
1188          *
1189          * @param array $options Associative array of options
1190          * @return string
1191          * @see DatabaseBase::select()
1192          * @since 1.21
1193          */
1194         public function makeOrderBy( $options ) {
1195                 if ( isset( $options['ORDER BY'] ) ) {
1196                         $ob = is_array( $options['ORDER BY'] )
1197                                 ? implode( ',', $options['ORDER BY'] )
1198                                 : $options['ORDER BY'];
1199
1200                         return ' ORDER BY ' . $ob;
1201                 }
1202
1203                 return '';
1204         }
1205
1206         // See IDatabase::select for the docs for this function
1207         public function select( $table, $vars, $conds = '', $fname = __METHOD__,
1208                 $options = [], $join_conds = [] ) {
1209                 $sql = $this->selectSQLText( $table, $vars, $conds, $fname, $options, $join_conds );
1210
1211                 return $this->query( $sql, $fname );
1212         }
1213
1214         public function selectSQLText( $table, $vars, $conds = '', $fname = __METHOD__,
1215                 $options = [], $join_conds = []
1216         ) {
1217                 if ( is_array( $vars ) ) {
1218                         $vars = implode( ',', $this->fieldNamesWithAlias( $vars ) );
1219                 }
1220
1221                 $options = (array)$options;
1222                 $useIndexes = ( isset( $options['USE INDEX'] ) && is_array( $options['USE INDEX'] ) )
1223                         ? $options['USE INDEX']
1224                         : [];
1225                 $ignoreIndexes = ( isset( $options['IGNORE INDEX'] ) && is_array( $options['IGNORE INDEX'] ) )
1226                         ? $options['IGNORE INDEX']
1227                         : [];
1228
1229                 if ( is_array( $table ) ) {
1230                         $from = ' FROM ' .
1231                                 $this->tableNamesWithIndexClauseOrJOIN( $table, $useIndexes, $ignoreIndexes, $join_conds );
1232                 } elseif ( $table != '' ) {
1233                         if ( $table[0] == ' ' ) {
1234                                 $from = ' FROM ' . $table;
1235                         } else {
1236                                 $from = ' FROM ' .
1237                                         $this->tableNamesWithIndexClauseOrJOIN( [ $table ], $useIndexes, $ignoreIndexes, [] );
1238                         }
1239                 } else {
1240                         $from = '';
1241                 }
1242
1243                 list( $startOpts, $useIndex, $preLimitTail, $postLimitTail, $ignoreIndex ) =
1244                         $this->makeSelectOptions( $options );
1245
1246                 if ( !empty( $conds ) ) {
1247                         if ( is_array( $conds ) ) {
1248                                 $conds = $this->makeList( $conds, LIST_AND );
1249                         }
1250                         $sql = "SELECT $startOpts $vars $from $useIndex $ignoreIndex WHERE $conds $preLimitTail";
1251                 } else {
1252                         $sql = "SELECT $startOpts $vars $from $useIndex $ignoreIndex $preLimitTail";
1253                 }
1254
1255                 if ( isset( $options['LIMIT'] ) ) {
1256                         $sql = $this->limitResult( $sql, $options['LIMIT'],
1257                                 isset( $options['OFFSET'] ) ? $options['OFFSET'] : false );
1258                 }
1259                 $sql = "$sql $postLimitTail";
1260
1261                 if ( isset( $options['EXPLAIN'] ) ) {
1262                         $sql = 'EXPLAIN ' . $sql;
1263                 }
1264
1265                 return $sql;
1266         }
1267
1268         public function selectRow( $table, $vars, $conds, $fname = __METHOD__,
1269                 $options = [], $join_conds = []
1270         ) {
1271                 $options = (array)$options;
1272                 $options['LIMIT'] = 1;
1273                 $res = $this->select( $table, $vars, $conds, $fname, $options, $join_conds );
1274
1275                 if ( $res === false ) {
1276                         return false;
1277                 }
1278
1279                 if ( !$this->numRows( $res ) ) {
1280                         return false;
1281                 }
1282
1283                 $obj = $this->fetchObject( $res );
1284
1285                 return $obj;
1286         }
1287
1288         public function estimateRowCount(
1289                 $table, $vars = '*', $conds = '', $fname = __METHOD__, $options = []
1290         ) {
1291                 $rows = 0;
1292                 $res = $this->select( $table, [ 'rowcount' => 'COUNT(*)' ], $conds, $fname, $options );
1293
1294                 if ( $res ) {
1295                         $row = $this->fetchRow( $res );
1296                         $rows = ( isset( $row['rowcount'] ) ) ? (int)$row['rowcount'] : 0;
1297                 }
1298
1299                 return $rows;
1300         }
1301
1302         public function selectRowCount(
1303                 $tables, $vars = '*', $conds = '', $fname = __METHOD__, $options = [], $join_conds = []
1304         ) {
1305                 $rows = 0;
1306                 $sql = $this->selectSQLText( $tables, '1', $conds, $fname, $options, $join_conds );
1307                 $res = $this->query( "SELECT COUNT(*) AS rowcount FROM ($sql) tmp_count", $fname );
1308
1309                 if ( $res ) {
1310                         $row = $this->fetchRow( $res );
1311                         $rows = ( isset( $row['rowcount'] ) ) ? (int)$row['rowcount'] : 0;
1312                 }
1313
1314                 return $rows;
1315         }
1316
1317         /**
1318          * Removes most variables from an SQL query and replaces them with X or N for numbers.
1319          * It's only slightly flawed. Don't use for anything important.
1320          *
1321          * @param string $sql A SQL Query
1322          *
1323          * @return string
1324          */
1325         protected static function generalizeSQL( $sql ) {
1326                 # This does the same as the regexp below would do, but in such a way
1327                 # as to avoid crashing php on some large strings.
1328                 # $sql = preg_replace( "/'([^\\\\']|\\\\.)*'|\"([^\\\\\"]|\\\\.)*\"/", "'X'", $sql );
1329
1330                 $sql = str_replace( "\\\\", '', $sql );
1331                 $sql = str_replace( "\\'", '', $sql );
1332                 $sql = str_replace( "\\\"", '', $sql );
1333                 $sql = preg_replace( "/'.*'/s", "'X'", $sql );
1334                 $sql = preg_replace( '/".*"/s', "'X'", $sql );
1335
1336                 # All newlines, tabs, etc replaced by single space
1337                 $sql = preg_replace( '/\s+/', ' ', $sql );
1338
1339                 # All numbers => N,
1340                 # except the ones surrounded by characters, e.g. l10n
1341                 $sql = preg_replace( '/-?\d+(,-?\d+)+/s', 'N,...,N', $sql );
1342                 $sql = preg_replace( '/(?<![a-zA-Z])-?\d+(?![a-zA-Z])/s', 'N', $sql );
1343
1344                 return $sql;
1345         }
1346
1347         public function fieldExists( $table, $field, $fname = __METHOD__ ) {
1348                 $info = $this->fieldInfo( $table, $field );
1349
1350                 return (bool)$info;
1351         }
1352
1353         public function indexExists( $table, $index, $fname = __METHOD__ ) {
1354                 if ( !$this->tableExists( $table ) ) {
1355                         return null;
1356                 }
1357
1358                 $info = $this->indexInfo( $table, $index, $fname );
1359                 if ( is_null( $info ) ) {
1360                         return null;
1361                 } else {
1362                         return $info !== false;
1363                 }
1364         }
1365
1366         public function tableExists( $table, $fname = __METHOD__ ) {
1367                 $table = $this->tableName( $table );
1368                 $old = $this->ignoreErrors( true );
1369                 $res = $this->query( "SELECT 1 FROM $table LIMIT 1", $fname );
1370                 $this->ignoreErrors( $old );
1371
1372                 return (bool)$res;
1373         }
1374
1375         public function indexUnique( $table, $index ) {
1376                 $indexInfo = $this->indexInfo( $table, $index );
1377
1378                 if ( !$indexInfo ) {
1379                         return null;
1380                 }
1381
1382                 return !$indexInfo[0]->Non_unique;
1383         }
1384
1385         /**
1386          * Helper for DatabaseBase::insert().
1387          *
1388          * @param array $options
1389          * @return string
1390          */
1391         protected function makeInsertOptions( $options ) {
1392                 return implode( ' ', $options );
1393         }
1394
1395         public function insert( $table, $a, $fname = __METHOD__, $options = [] ) {
1396                 # No rows to insert, easy just return now
1397                 if ( !count( $a ) ) {
1398                         return true;
1399                 }
1400
1401                 $table = $this->tableName( $table );
1402
1403                 if ( !is_array( $options ) ) {
1404                         $options = [ $options ];
1405                 }
1406
1407                 $fh = null;
1408                 if ( isset( $options['fileHandle'] ) ) {
1409                         $fh = $options['fileHandle'];
1410                 }
1411                 $options = $this->makeInsertOptions( $options );
1412
1413                 if ( isset( $a[0] ) && is_array( $a[0] ) ) {
1414                         $multi = true;
1415                         $keys = array_keys( $a[0] );
1416                 } else {
1417                         $multi = false;
1418                         $keys = array_keys( $a );
1419                 }
1420
1421                 $sql = 'INSERT ' . $options .
1422                         " INTO $table (" . implode( ',', $keys ) . ') VALUES ';
1423
1424                 if ( $multi ) {
1425                         $first = true;
1426                         foreach ( $a as $row ) {
1427                                 if ( $first ) {
1428                                         $first = false;
1429                                 } else {
1430                                         $sql .= ',';
1431                                 }
1432                                 $sql .= '(' . $this->makeList( $row ) . ')';
1433                         }
1434                 } else {
1435                         $sql .= '(' . $this->makeList( $a ) . ')';
1436                 }
1437
1438                 if ( $fh !== null && false === fwrite( $fh, $sql ) ) {
1439                         return false;
1440                 } elseif ( $fh !== null ) {
1441                         return true;
1442                 }
1443
1444                 return (bool)$this->query( $sql, $fname );
1445         }
1446
1447         /**
1448          * Make UPDATE options array for DatabaseBase::makeUpdateOptions
1449          *
1450          * @param array $options
1451          * @return array
1452          */
1453         protected function makeUpdateOptionsArray( $options ) {
1454                 if ( !is_array( $options ) ) {
1455                         $options = [ $options ];
1456                 }
1457
1458                 $opts = [];
1459
1460                 if ( in_array( 'IGNORE', $options ) ) {
1461                         $opts[] = 'IGNORE';
1462                 }
1463
1464                 return $opts;
1465         }
1466
1467         /**
1468          * Make UPDATE options for the DatabaseBase::update function
1469          *
1470          * @param array $options The options passed to DatabaseBase::update
1471          * @return string
1472          */
1473         protected function makeUpdateOptions( $options ) {
1474                 $opts = $this->makeUpdateOptionsArray( $options );
1475
1476                 return implode( ' ', $opts );
1477         }
1478
1479         function update( $table, $values, $conds, $fname = __METHOD__, $options = [] ) {
1480                 $table = $this->tableName( $table );
1481                 $opts = $this->makeUpdateOptions( $options );
1482                 $sql = "UPDATE $opts $table SET " . $this->makeList( $values, LIST_SET );
1483
1484                 if ( $conds !== [] && $conds !== '*' ) {
1485                         $sql .= " WHERE " . $this->makeList( $conds, LIST_AND );
1486                 }
1487
1488                 return $this->query( $sql, $fname );
1489         }
1490
1491         public function makeList( $a, $mode = LIST_COMMA ) {
1492                 if ( !is_array( $a ) ) {
1493                         throw new DBUnexpectedError( $this, __METHOD__ . ' called with incorrect parameters' );
1494                 }
1495
1496                 $first = true;
1497                 $list = '';
1498
1499                 foreach ( $a as $field => $value ) {
1500                         if ( !$first ) {
1501                                 if ( $mode == LIST_AND ) {
1502                                         $list .= ' AND ';
1503                                 } elseif ( $mode == LIST_OR ) {
1504                                         $list .= ' OR ';
1505                                 } else {
1506                                         $list .= ',';
1507                                 }
1508                         } else {
1509                                 $first = false;
1510                         }
1511
1512                         if ( ( $mode == LIST_AND || $mode == LIST_OR ) && is_numeric( $field ) ) {
1513                                 $list .= "($value)";
1514                         } elseif ( ( $mode == LIST_SET ) && is_numeric( $field ) ) {
1515                                 $list .= "$value";
1516                         } elseif ( ( $mode == LIST_AND || $mode == LIST_OR ) && is_array( $value ) ) {
1517                                 // Remove null from array to be handled separately if found
1518                                 $includeNull = false;
1519                                 foreach ( array_keys( $value, null, true ) as $nullKey ) {
1520                                         $includeNull = true;
1521                                         unset( $value[$nullKey] );
1522                                 }
1523                                 if ( count( $value ) == 0 && !$includeNull ) {
1524                                         throw new InvalidArgumentException( __METHOD__ . ": empty input for field $field" );
1525                                 } elseif ( count( $value ) == 0 ) {
1526                                         // only check if $field is null
1527                                         $list .= "$field IS NULL";
1528                                 } else {
1529                                         // IN clause contains at least one valid element
1530                                         if ( $includeNull ) {
1531                                                 // Group subconditions to ensure correct precedence
1532                                                 $list .= '(';
1533                                         }
1534                                         if ( count( $value ) == 1 ) {
1535                                                 // Special-case single values, as IN isn't terribly efficient
1536                                                 // Don't necessarily assume the single key is 0; we don't
1537                                                 // enforce linear numeric ordering on other arrays here.
1538                                                 $value = array_values( $value )[0];
1539                                                 $list .= $field . " = " . $this->addQuotes( $value );
1540                                         } else {
1541                                                 $list .= $field . " IN (" . $this->makeList( $value ) . ") ";
1542                                         }
1543                                         // if null present in array, append IS NULL
1544                                         if ( $includeNull ) {
1545                                                 $list .= " OR $field IS NULL)";
1546                                         }
1547                                 }
1548                         } elseif ( $value === null ) {
1549                                 if ( $mode == LIST_AND || $mode == LIST_OR ) {
1550                                         $list .= "$field IS ";
1551                                 } elseif ( $mode == LIST_SET ) {
1552                                         $list .= "$field = ";
1553                                 }
1554                                 $list .= 'NULL';
1555                         } else {
1556                                 if ( $mode == LIST_AND || $mode == LIST_OR || $mode == LIST_SET ) {
1557                                         $list .= "$field = ";
1558                                 }
1559                                 $list .= $mode == LIST_NAMES ? $value : $this->addQuotes( $value );
1560                         }
1561                 }
1562
1563                 return $list;
1564         }
1565
1566         public function makeWhereFrom2d( $data, $baseKey, $subKey ) {
1567                 $conds = [];
1568
1569                 foreach ( $data as $base => $sub ) {
1570                         if ( count( $sub ) ) {
1571                                 $conds[] = $this->makeList(
1572                                         [ $baseKey => $base, $subKey => array_keys( $sub ) ],
1573                                         LIST_AND );
1574                         }
1575                 }
1576
1577                 if ( $conds ) {
1578                         return $this->makeList( $conds, LIST_OR );
1579                 } else {
1580                         // Nothing to search for...
1581                         return false;
1582                 }
1583         }
1584
1585         /**
1586          * Return aggregated value alias
1587          *
1588          * @param array $valuedata
1589          * @param string $valuename
1590          *
1591          * @return string
1592          */
1593         public function aggregateValue( $valuedata, $valuename = 'value' ) {
1594                 return $valuename;
1595         }
1596
1597         public function bitNot( $field ) {
1598                 return "(~$field)";
1599         }
1600
1601         public function bitAnd( $fieldLeft, $fieldRight ) {
1602                 return "($fieldLeft & $fieldRight)";
1603         }
1604
1605         public function bitOr( $fieldLeft, $fieldRight ) {
1606                 return "($fieldLeft | $fieldRight)";
1607         }
1608
1609         public function buildConcat( $stringList ) {
1610                 return 'CONCAT(' . implode( ',', $stringList ) . ')';
1611         }
1612
1613         public function buildGroupConcatField(
1614                 $delim, $table, $field, $conds = '', $join_conds = []
1615         ) {
1616                 $fld = "GROUP_CONCAT($field SEPARATOR " . $this->addQuotes( $delim ) . ')';
1617
1618                 return '(' . $this->selectSQLText( $table, $fld, $conds, null, [], $join_conds ) . ')';
1619         }
1620
1621         /**
1622          * @param string $field Field or column to cast
1623          * @return string
1624          * @since 1.28
1625          */
1626         public function buildStringCast( $field ) {
1627                 return $field;
1628         }
1629
1630         public function selectDB( $db ) {
1631                 # Stub. Shouldn't cause serious problems if it's not overridden, but
1632                 # if your database engine supports a concept similar to MySQL's
1633                 # databases you may as well.
1634                 $this->mDBname = $db;
1635
1636                 return true;
1637         }
1638
1639         public function getDBname() {
1640                 return $this->mDBname;
1641         }
1642
1643         public function getServer() {
1644                 return $this->mServer;
1645         }
1646
1647         /**
1648          * Format a table name ready for use in constructing an SQL query
1649          *
1650          * This does two important things: it quotes the table names to clean them up,
1651          * and it adds a table prefix if only given a table name with no quotes.
1652          *
1653          * All functions of this object which require a table name call this function
1654          * themselves. Pass the canonical name to such functions. This is only needed
1655          * when calling query() directly.
1656          *
1657          * @note This function does not sanitize user input. It is not safe to use
1658          *   this function to escape user input.
1659          * @param string $name Database table name
1660          * @param string $format One of:
1661          *   quoted - Automatically pass the table name through addIdentifierQuotes()
1662          *            so that it can be used in a query.
1663          *   raw - Do not add identifier quotes to the table name
1664          * @return string Full database name
1665          */
1666         public function tableName( $name, $format = 'quoted' ) {
1667                 # Skip the entire process when we have a string quoted on both ends.
1668                 # Note that we check the end so that we will still quote any use of
1669                 # use of `database`.table. But won't break things if someone wants
1670                 # to query a database table with a dot in the name.
1671                 if ( $this->isQuotedIdentifier( $name ) ) {
1672                         return $name;
1673                 }
1674
1675                 # Lets test for any bits of text that should never show up in a table
1676                 # name. Basically anything like JOIN or ON which are actually part of
1677                 # SQL queries, but may end up inside of the table value to combine
1678                 # sql. Such as how the API is doing.
1679                 # Note that we use a whitespace test rather than a \b test to avoid
1680                 # any remote case where a word like on may be inside of a table name
1681                 # surrounded by symbols which may be considered word breaks.
1682                 if ( preg_match( '/(^|\s)(DISTINCT|JOIN|ON|AS)(\s|$)/i', $name ) !== 0 ) {
1683                         return $name;
1684                 }
1685
1686                 # Split database and table into proper variables.
1687                 # We reverse the explode so that database.table and table both output
1688                 # the correct table.
1689                 $dbDetails = explode( '.', $name, 3 );
1690                 if ( count( $dbDetails ) == 3 ) {
1691                         list( $database, $schema, $table ) = $dbDetails;
1692                         # We don't want any prefix added in this case
1693                         $prefix = '';
1694                 } elseif ( count( $dbDetails ) == 2 ) {
1695                         list( $database, $table ) = $dbDetails;
1696                         # We don't want any prefix added in this case
1697                         # In dbs that support it, $database may actually be the schema
1698                         # but that doesn't affect any of the functionality here
1699                         $prefix = '';
1700                         $schema = '';
1701                 } else {
1702                         list( $table ) = $dbDetails;
1703                         if ( isset( $this->tableAliases[$table] ) ) {
1704                                 $database = $this->tableAliases[$table]['dbname'];
1705                                 $schema = is_string( $this->tableAliases[$table]['schema'] )
1706                                         ? $this->tableAliases[$table]['schema']
1707                                         : $this->mSchema;
1708                                 $prefix = is_string( $this->tableAliases[$table]['prefix'] )
1709                                         ? $this->tableAliases[$table]['prefix']
1710                                         : $this->mTablePrefix;
1711                         } else {
1712                                 $database = '';
1713                                 $schema = $this->mSchema; # Default schema
1714                                 $prefix = $this->mTablePrefix; # Default prefix
1715                         }
1716                 }
1717
1718                 # Quote $table and apply the prefix if not quoted.
1719                 # $tableName might be empty if this is called from Database::replaceVars()
1720                 $tableName = "{$prefix}{$table}";
1721                 if ( $format == 'quoted'
1722                         && !$this->isQuotedIdentifier( $tableName ) && $tableName !== ''
1723                 ) {
1724                         $tableName = $this->addIdentifierQuotes( $tableName );
1725                 }
1726
1727                 # Quote $schema and merge it with the table name if needed
1728                 if ( strlen( $schema ) ) {
1729                         if ( $format == 'quoted' && !$this->isQuotedIdentifier( $schema ) ) {
1730                                 $schema = $this->addIdentifierQuotes( $schema );
1731                         }
1732                         $tableName = $schema . '.' . $tableName;
1733                 }
1734
1735                 # Quote $database and merge it with the table name if needed
1736                 if ( $database !== '' ) {
1737                         if ( $format == 'quoted' && !$this->isQuotedIdentifier( $database ) ) {
1738                                 $database = $this->addIdentifierQuotes( $database );
1739                         }
1740                         $tableName = $database . '.' . $tableName;
1741                 }
1742
1743                 return $tableName;
1744         }
1745
1746         /**
1747          * Fetch a number of table names into an array
1748          * This is handy when you need to construct SQL for joins
1749          *
1750          * Example:
1751          * extract( $dbr->tableNames( 'user', 'watchlist' ) );
1752          * $sql = "SELECT wl_namespace,wl_title FROM $watchlist,$user
1753          *         WHERE wl_user=user_id AND wl_user=$nameWithQuotes";
1754          *
1755          * @return array
1756          */
1757         public function tableNames() {
1758                 $inArray = func_get_args();
1759                 $retVal = [];
1760
1761                 foreach ( $inArray as $name ) {
1762                         $retVal[$name] = $this->tableName( $name );
1763                 }
1764
1765                 return $retVal;
1766         }
1767
1768         /**
1769          * Fetch a number of table names into an zero-indexed numerical array
1770          * This is handy when you need to construct SQL for joins
1771          *
1772          * Example:
1773          * list( $user, $watchlist ) = $dbr->tableNamesN( 'user', 'watchlist' );
1774          * $sql = "SELECT wl_namespace,wl_title FROM $watchlist,$user
1775          *         WHERE wl_user=user_id AND wl_user=$nameWithQuotes";
1776          *
1777          * @return array
1778          */
1779         public function tableNamesN() {
1780                 $inArray = func_get_args();
1781                 $retVal = [];
1782
1783                 foreach ( $inArray as $name ) {
1784                         $retVal[] = $this->tableName( $name );
1785                 }
1786
1787                 return $retVal;
1788         }
1789
1790         /**
1791          * Get an aliased table name
1792          * e.g. tableName AS newTableName
1793          *
1794          * @param string $name Table name, see tableName()
1795          * @param string|bool $alias Alias (optional)
1796          * @return string SQL name for aliased table. Will not alias a table to its own name
1797          */
1798         public function tableNameWithAlias( $name, $alias = false ) {
1799                 if ( !$alias || $alias == $name ) {
1800                         return $this->tableName( $name );
1801                 } else {
1802                         return $this->tableName( $name ) . ' ' . $this->addIdentifierQuotes( $alias );
1803                 }
1804         }
1805
1806         /**
1807          * Gets an array of aliased table names
1808          *
1809          * @param array $tables [ [alias] => table ]
1810          * @return string[] See tableNameWithAlias()
1811          */
1812         public function tableNamesWithAlias( $tables ) {
1813                 $retval = [];
1814                 foreach ( $tables as $alias => $table ) {
1815                         if ( is_numeric( $alias ) ) {
1816                                 $alias = $table;
1817                         }
1818                         $retval[] = $this->tableNameWithAlias( $table, $alias );
1819                 }
1820
1821                 return $retval;
1822         }
1823
1824         /**
1825          * Get an aliased field name
1826          * e.g. fieldName AS newFieldName
1827          *
1828          * @param string $name Field name
1829          * @param string|bool $alias Alias (optional)
1830          * @return string SQL name for aliased field. Will not alias a field to its own name
1831          */
1832         public function fieldNameWithAlias( $name, $alias = false ) {
1833                 if ( !$alias || (string)$alias === (string)$name ) {
1834                         return $name;
1835                 } else {
1836                         return $name . ' AS ' . $this->addIdentifierQuotes( $alias ); // PostgreSQL needs AS
1837                 }
1838         }
1839
1840         /**
1841          * Gets an array of aliased field names
1842          *
1843          * @param array $fields [ [alias] => field ]
1844          * @return string[] See fieldNameWithAlias()
1845          */
1846         public function fieldNamesWithAlias( $fields ) {
1847                 $retval = [];
1848                 foreach ( $fields as $alias => $field ) {
1849                         if ( is_numeric( $alias ) ) {
1850                                 $alias = $field;
1851                         }
1852                         $retval[] = $this->fieldNameWithAlias( $field, $alias );
1853                 }
1854
1855                 return $retval;
1856         }
1857
1858         /**
1859          * Get the aliased table name clause for a FROM clause
1860          * which might have a JOIN and/or USE INDEX or IGNORE INDEX clause
1861          *
1862          * @param array $tables ( [alias] => table )
1863          * @param array $use_index Same as for select()
1864          * @param array $ignore_index Same as for select()
1865          * @param array $join_conds Same as for select()
1866          * @return string
1867          */
1868         protected function tableNamesWithIndexClauseOrJOIN(
1869                 $tables, $use_index = [], $ignore_index = [], $join_conds = []
1870         ) {
1871                 $ret = [];
1872                 $retJOIN = [];
1873                 $use_index = (array)$use_index;
1874                 $ignore_index = (array)$ignore_index;
1875                 $join_conds = (array)$join_conds;
1876
1877                 foreach ( $tables as $alias => $table ) {
1878                         if ( !is_string( $alias ) ) {
1879                                 // No alias? Set it equal to the table name
1880                                 $alias = $table;
1881                         }
1882                         // Is there a JOIN clause for this table?
1883                         if ( isset( $join_conds[$alias] ) ) {
1884                                 list( $joinType, $conds ) = $join_conds[$alias];
1885                                 $tableClause = $joinType;
1886                                 $tableClause .= ' ' . $this->tableNameWithAlias( $table, $alias );
1887                                 if ( isset( $use_index[$alias] ) ) { // has USE INDEX?
1888                                         $use = $this->useIndexClause( implode( ',', (array)$use_index[$alias] ) );
1889                                         if ( $use != '' ) {
1890                                                 $tableClause .= ' ' . $use;
1891                                         }
1892                                 }
1893                                 if ( isset( $ignore_index[$alias] ) ) { // has IGNORE INDEX?
1894                                         $ignore = $this->ignoreIndexClause( implode( ',', (array)$ignore_index[$alias] ) );
1895                                         if ( $ignore != '' ) {
1896                                                 $tableClause .= ' ' . $ignore;
1897                                         }
1898                                 }
1899                                 $on = $this->makeList( (array)$conds, LIST_AND );
1900                                 if ( $on != '' ) {
1901                                         $tableClause .= ' ON (' . $on . ')';
1902                                 }
1903
1904                                 $retJOIN[] = $tableClause;
1905                         } elseif ( isset( $use_index[$alias] ) ) {
1906                                 // Is there an INDEX clause for this table?
1907                                 $tableClause = $this->tableNameWithAlias( $table, $alias );
1908                                 $tableClause .= ' ' . $this->useIndexClause(
1909                                                 implode( ',', (array)$use_index[$alias] )
1910                                         );
1911
1912                                 $ret[] = $tableClause;
1913                         } elseif ( isset( $ignore_index[$alias] ) ) {
1914                                 // Is there an INDEX clause for this table?
1915                                 $tableClause = $this->tableNameWithAlias( $table, $alias );
1916                                 $tableClause .= ' ' . $this->ignoreIndexClause(
1917                                                 implode( ',', (array)$ignore_index[$alias] )
1918                                         );
1919
1920                                 $ret[] = $tableClause;
1921                         } else {
1922                                 $tableClause = $this->tableNameWithAlias( $table, $alias );
1923
1924                                 $ret[] = $tableClause;
1925                         }
1926                 }
1927
1928                 // We can't separate explicit JOIN clauses with ',', use ' ' for those
1929                 $implicitJoins = !empty( $ret ) ? implode( ',', $ret ) : "";
1930                 $explicitJoins = !empty( $retJOIN ) ? implode( ' ', $retJOIN ) : "";
1931
1932                 // Compile our final table clause
1933                 return implode( ' ', [ $implicitJoins, $explicitJoins ] );
1934         }
1935
1936         /**
1937          * Get the name of an index in a given table.
1938          *
1939          * @param string $index
1940          * @return string
1941          */
1942         protected function indexName( $index ) {
1943                 // Backwards-compatibility hack
1944                 $renamed = [
1945                         'ar_usertext_timestamp' => 'usertext_timestamp',
1946                         'un_user_id' => 'user_id',
1947                         'un_user_ip' => 'user_ip',
1948                 ];
1949
1950                 if ( isset( $renamed[$index] ) ) {
1951                         return $renamed[$index];
1952                 } else {
1953                         return $index;
1954                 }
1955         }
1956
1957         public function addQuotes( $s ) {
1958                 if ( $s instanceof Blob ) {
1959                         $s = $s->fetch();
1960                 }
1961                 if ( $s === null ) {
1962                         return 'NULL';
1963                 } else {
1964                         # This will also quote numeric values. This should be harmless,
1965                         # and protects against weird problems that occur when they really
1966                         # _are_ strings such as article titles and string->number->string
1967                         # conversion is not 1:1.
1968                         return "'" . $this->strencode( $s ) . "'";
1969                 }
1970         }
1971
1972         /**
1973          * Quotes an identifier using `backticks` or "double quotes" depending on the database type.
1974          * MySQL uses `backticks` while basically everything else uses double quotes.
1975          * Since MySQL is the odd one out here the double quotes are our generic
1976          * and we implement backticks in DatabaseMysql.
1977          *
1978          * @param string $s
1979          * @return string
1980          */
1981         public function addIdentifierQuotes( $s ) {
1982                 return '"' . str_replace( '"', '""', $s ) . '"';
1983         }
1984
1985         /**
1986          * Returns if the given identifier looks quoted or not according to
1987          * the database convention for quoting identifiers .
1988          *
1989          * @note Do not use this to determine if untrusted input is safe.
1990          *   A malicious user can trick this function.
1991          * @param string $name
1992          * @return bool
1993          */
1994         public function isQuotedIdentifier( $name ) {
1995                 return $name[0] == '"' && substr( $name, -1, 1 ) == '"';
1996         }
1997
1998         /**
1999          * @param string $s
2000          * @return string
2001          */
2002         protected function escapeLikeInternal( $s ) {
2003                 return addcslashes( $s, '\%_' );
2004         }
2005
2006         public function buildLike() {
2007                 $params = func_get_args();
2008
2009                 if ( count( $params ) > 0 && is_array( $params[0] ) ) {
2010                         $params = $params[0];
2011                 }
2012
2013                 $s = '';
2014
2015                 foreach ( $params as $value ) {
2016                         if ( $value instanceof LikeMatch ) {
2017                                 $s .= $value->toString();
2018                         } else {
2019                                 $s .= $this->escapeLikeInternal( $value );
2020                         }
2021                 }
2022
2023                 return " LIKE {$this->addQuotes( $s )} ";
2024         }
2025
2026         public function anyChar() {
2027                 return new LikeMatch( '_' );
2028         }
2029
2030         public function anyString() {
2031                 return new LikeMatch( '%' );
2032         }
2033
2034         public function nextSequenceValue( $seqName ) {
2035                 return null;
2036         }
2037
2038         /**
2039          * USE INDEX clause. Unlikely to be useful for anything but MySQL. This
2040          * is only needed because a) MySQL must be as efficient as possible due to
2041          * its use on Wikipedia, and b) MySQL 4.0 is kind of dumb sometimes about
2042          * which index to pick. Anyway, other databases might have different
2043          * indexes on a given table. So don't bother overriding this unless you're
2044          * MySQL.
2045          * @param string $index
2046          * @return string
2047          */
2048         public function useIndexClause( $index ) {
2049                 return '';
2050         }
2051
2052         /**
2053          * IGNORE INDEX clause. Unlikely to be useful for anything but MySQL. This
2054          * is only needed because a) MySQL must be as efficient as possible due to
2055          * its use on Wikipedia, and b) MySQL 4.0 is kind of dumb sometimes about
2056          * which index to pick. Anyway, other databases might have different
2057          * indexes on a given table. So don't bother overriding this unless you're
2058          * MySQL.
2059          * @param string $index
2060          * @return string
2061          */
2062         public function ignoreIndexClause( $index ) {
2063                 return '';
2064         }
2065
2066         public function replace( $table, $uniqueIndexes, $rows, $fname = __METHOD__ ) {
2067                 $quotedTable = $this->tableName( $table );
2068
2069                 if ( count( $rows ) == 0 ) {
2070                         return;
2071                 }
2072
2073                 # Single row case
2074                 if ( !is_array( reset( $rows ) ) ) {
2075                         $rows = [ $rows ];
2076                 }
2077
2078                 // @FXIME: this is not atomic, but a trx would break affectedRows()
2079                 foreach ( $rows as $row ) {
2080                         # Delete rows which collide
2081                         if ( $uniqueIndexes ) {
2082                                 $sql = "DELETE FROM $quotedTable WHERE ";
2083                                 $first = true;
2084                                 foreach ( $uniqueIndexes as $index ) {
2085                                         if ( $first ) {
2086                                                 $first = false;
2087                                                 $sql .= '( ';
2088                                         } else {
2089                                                 $sql .= ' ) OR ( ';
2090                                         }
2091                                         if ( is_array( $index ) ) {
2092                                                 $first2 = true;
2093                                                 foreach ( $index as $col ) {
2094                                                         if ( $first2 ) {
2095                                                                 $first2 = false;
2096                                                         } else {
2097                                                                 $sql .= ' AND ';
2098                                                         }
2099                                                         $sql .= $col . '=' . $this->addQuotes( $row[$col] );
2100                                                 }
2101                                         } else {
2102                                                 $sql .= $index . '=' . $this->addQuotes( $row[$index] );
2103                                         }
2104                                 }
2105                                 $sql .= ' )';
2106                                 $this->query( $sql, $fname );
2107                         }
2108
2109                         # Now insert the row
2110                         $this->insert( $table, $row, $fname );
2111                 }
2112         }
2113
2114         /**
2115          * REPLACE query wrapper for MySQL and SQLite, which have a native REPLACE
2116          * statement.
2117          *
2118          * @param string $table Table name
2119          * @param array|string $rows Row(s) to insert
2120          * @param string $fname Caller function name
2121          *
2122          * @return ResultWrapper
2123          */
2124         protected function nativeReplace( $table, $rows, $fname ) {
2125                 $table = $this->tableName( $table );
2126
2127                 # Single row case
2128                 if ( !is_array( reset( $rows ) ) ) {
2129                         $rows = [ $rows ];
2130                 }
2131
2132                 $sql = "REPLACE INTO $table (" . implode( ',', array_keys( $rows[0] ) ) . ') VALUES ';
2133                 $first = true;
2134
2135                 foreach ( $rows as $row ) {
2136                         if ( $first ) {
2137                                 $first = false;
2138                         } else {
2139                                 $sql .= ',';
2140                         }
2141
2142                         $sql .= '(' . $this->makeList( $row ) . ')';
2143                 }
2144
2145                 return $this->query( $sql, $fname );
2146         }
2147
2148         public function upsert( $table, array $rows, array $uniqueIndexes, array $set,
2149                 $fname = __METHOD__
2150         ) {
2151                 if ( !count( $rows ) ) {
2152                         return true; // nothing to do
2153                 }
2154
2155                 if ( !is_array( reset( $rows ) ) ) {
2156                         $rows = [ $rows ];
2157                 }
2158
2159                 if ( count( $uniqueIndexes ) ) {
2160                         $clauses = []; // list WHERE clauses that each identify a single row
2161                         foreach ( $rows as $row ) {
2162                                 foreach ( $uniqueIndexes as $index ) {
2163                                         $index = is_array( $index ) ? $index : [ $index ]; // columns
2164                                         $rowKey = []; // unique key to this row
2165                                         foreach ( $index as $column ) {
2166                                                 $rowKey[$column] = $row[$column];
2167                                         }
2168                                         $clauses[] = $this->makeList( $rowKey, LIST_AND );
2169                                 }
2170                         }
2171                         $where = [ $this->makeList( $clauses, LIST_OR ) ];
2172                 } else {
2173                         $where = false;
2174                 }
2175
2176                 $useTrx = !$this->mTrxLevel;
2177                 if ( $useTrx ) {
2178                         $this->begin( $fname, self::TRANSACTION_INTERNAL );
2179                 }
2180                 try {
2181                         # Update any existing conflicting row(s)
2182                         if ( $where !== false ) {
2183                                 $ok = $this->update( $table, $set, $where, $fname );
2184                         } else {
2185                                 $ok = true;
2186                         }
2187                         # Now insert any non-conflicting row(s)
2188                         $ok = $this->insert( $table, $rows, $fname, [ 'IGNORE' ] ) && $ok;
2189                 } catch ( Exception $e ) {
2190                         if ( $useTrx ) {
2191                                 $this->rollback( $fname, self::FLUSHING_INTERNAL );
2192                         }
2193                         throw $e;
2194                 }
2195                 if ( $useTrx ) {
2196                         $this->commit( $fname, self::FLUSHING_INTERNAL );
2197                 }
2198
2199                 return $ok;
2200         }
2201
2202         public function deleteJoin( $delTable, $joinTable, $delVar, $joinVar, $conds,
2203                 $fname = __METHOD__
2204         ) {
2205                 if ( !$conds ) {
2206                         throw new DBUnexpectedError( $this, __METHOD__ . ' called with empty $conds' );
2207                 }
2208
2209                 $delTable = $this->tableName( $delTable );
2210                 $joinTable = $this->tableName( $joinTable );
2211                 $sql = "DELETE FROM $delTable WHERE $delVar IN (SELECT $joinVar FROM $joinTable ";
2212                 if ( $conds != '*' ) {
2213                         $sql .= 'WHERE ' . $this->makeList( $conds, LIST_AND );
2214                 }
2215                 $sql .= ')';
2216
2217                 $this->query( $sql, $fname );
2218         }
2219
2220         /**
2221          * Returns the size of a text field, or -1 for "unlimited"
2222          *
2223          * @param string $table
2224          * @param string $field
2225          * @return int
2226          */
2227         public function textFieldSize( $table, $field ) {
2228                 $table = $this->tableName( $table );
2229                 $sql = "SHOW COLUMNS FROM $table LIKE \"$field\";";
2230                 $res = $this->query( $sql, __METHOD__ );
2231                 $row = $this->fetchObject( $res );
2232
2233                 $m = [];
2234
2235                 if ( preg_match( '/\((.*)\)/', $row->Type, $m ) ) {
2236                         $size = $m[1];
2237                 } else {
2238                         $size = -1;
2239                 }
2240
2241                 return $size;
2242         }
2243
2244         public function delete( $table, $conds, $fname = __METHOD__ ) {
2245                 if ( !$conds ) {
2246                         throw new DBUnexpectedError( $this, __METHOD__ . ' called with no conditions' );
2247                 }
2248
2249                 $table = $this->tableName( $table );
2250                 $sql = "DELETE FROM $table";
2251
2252                 if ( $conds != '*' ) {
2253                         if ( is_array( $conds ) ) {
2254                                 $conds = $this->makeList( $conds, LIST_AND );
2255                         }
2256                         $sql .= ' WHERE ' . $conds;
2257                 }
2258
2259                 return $this->query( $sql, $fname );
2260         }
2261
2262         public function insertSelect(
2263                 $destTable, $srcTable, $varMap, $conds,
2264                 $fname = __METHOD__, $insertOptions = [], $selectOptions = []
2265         ) {
2266                 if ( $this->cliMode ) {
2267                         // For massive migrations with downtime, we don't want to select everything
2268                         // into memory and OOM, so do all this native on the server side if possible.
2269                         return $this->nativeInsertSelect(
2270                                 $destTable,
2271                                 $srcTable,
2272                                 $varMap,
2273                                 $conds,
2274                                 $fname,
2275                                 $insertOptions,
2276                                 $selectOptions
2277                         );
2278                 }
2279
2280                 // For web requests, do a locking SELECT and then INSERT. This puts the SELECT burden
2281                 // on only the master (without needing row-based-replication). It also makes it easy to
2282                 // know how big the INSERT is going to be.
2283                 $fields = [];
2284                 foreach ( $varMap as $dstColumn => $sourceColumnOrSql ) {
2285                         $fields[] = $this->fieldNameWithAlias( $sourceColumnOrSql, $dstColumn );
2286                 }
2287                 $selectOptions[] = 'FOR UPDATE';
2288                 $res = $this->select( $srcTable, implode( ',', $fields ), $conds, $fname, $selectOptions );
2289                 if ( !$res ) {
2290                         return false;
2291                 }
2292
2293                 $rows = [];
2294                 foreach ( $res as $row ) {
2295                         $rows[] = (array)$row;
2296                 }
2297
2298                 return $this->insert( $destTable, $rows, $fname, $insertOptions );
2299         }
2300
2301         public function nativeInsertSelect( $destTable, $srcTable, $varMap, $conds,
2302                 $fname = __METHOD__,
2303                 $insertOptions = [], $selectOptions = []
2304         ) {
2305                 $destTable = $this->tableName( $destTable );
2306
2307                 if ( !is_array( $insertOptions ) ) {
2308                         $insertOptions = [ $insertOptions ];
2309                 }
2310
2311                 $insertOptions = $this->makeInsertOptions( $insertOptions );
2312
2313                 if ( !is_array( $selectOptions ) ) {
2314                         $selectOptions = [ $selectOptions ];
2315                 }
2316
2317                 list( $startOpts, $useIndex, $tailOpts, $ignoreIndex ) = $this->makeSelectOptions(
2318                         $selectOptions );
2319
2320                 if ( is_array( $srcTable ) ) {
2321                         $srcTable = implode( ',', array_map( [ &$this, 'tableName' ], $srcTable ) );
2322                 } else {
2323                         $srcTable = $this->tableName( $srcTable );
2324                 }
2325
2326                 $sql = "INSERT $insertOptions INTO $destTable (" . implode( ',', array_keys( $varMap ) ) . ')' .
2327                         " SELECT $startOpts " . implode( ',', $varMap ) .
2328                         " FROM $srcTable $useIndex $ignoreIndex ";
2329
2330                 if ( $conds != '*' ) {
2331                         if ( is_array( $conds ) ) {
2332                                 $conds = $this->makeList( $conds, LIST_AND );
2333                         }
2334                         $sql .= " WHERE $conds";
2335                 }
2336
2337                 $sql .= " $tailOpts";
2338
2339                 return $this->query( $sql, $fname );
2340         }
2341
2342         /**
2343          * Construct a LIMIT query with optional offset. This is used for query
2344          * pages. The SQL should be adjusted so that only the first $limit rows
2345          * are returned. If $offset is provided as well, then the first $offset
2346          * rows should be discarded, and the next $limit rows should be returned.
2347          * If the result of the query is not ordered, then the rows to be returned
2348          * are theoretically arbitrary.
2349          *
2350          * $sql is expected to be a SELECT, if that makes a difference.
2351          *
2352          * The version provided by default works in MySQL and SQLite. It will very
2353          * likely need to be overridden for most other DBMSes.
2354          *
2355          * @param string $sql SQL query we will append the limit too
2356          * @param int $limit The SQL limit
2357          * @param int|bool $offset The SQL offset (default false)
2358          * @throws DBUnexpectedError
2359          * @return string
2360          */
2361         public function limitResult( $sql, $limit, $offset = false ) {
2362                 if ( !is_numeric( $limit ) ) {
2363                         throw new DBUnexpectedError( $this, "Invalid non-numeric limit passed to limitResult()\n" );
2364                 }
2365
2366                 return "$sql LIMIT "
2367                 . ( ( is_numeric( $offset ) && $offset != 0 ) ? "{$offset}," : "" )
2368                 . "{$limit} ";
2369         }
2370
2371         public function unionSupportsOrderAndLimit() {
2372                 return true; // True for almost every DB supported
2373         }
2374
2375         public function unionQueries( $sqls, $all ) {
2376                 $glue = $all ? ') UNION ALL (' : ') UNION (';
2377
2378                 return '(' . implode( $glue, $sqls ) . ')';
2379         }
2380
2381         public function conditional( $cond, $trueVal, $falseVal ) {
2382                 if ( is_array( $cond ) ) {
2383                         $cond = $this->makeList( $cond, LIST_AND );
2384                 }
2385
2386                 return " (CASE WHEN $cond THEN $trueVal ELSE $falseVal END) ";
2387         }
2388
2389         public function strreplace( $orig, $old, $new ) {
2390                 return "REPLACE({$orig}, {$old}, {$new})";
2391         }
2392
2393         public function getServerUptime() {
2394                 return 0;
2395         }
2396
2397         public function wasDeadlock() {
2398                 return false;
2399         }
2400
2401         public function wasLockTimeout() {
2402                 return false;
2403         }
2404
2405         public function wasErrorReissuable() {
2406                 return false;
2407         }
2408
2409         public function wasReadOnlyError() {
2410                 return false;
2411         }
2412
2413         /**
2414          * Determines if the given query error was a connection drop
2415          * STUB
2416          *
2417          * @param integer|string $errno
2418          * @return bool
2419          */
2420         public function wasConnectionError( $errno ) {
2421                 return false;
2422         }
2423
2424         /**
2425          * Perform a deadlock-prone transaction.
2426          *
2427          * This function invokes a callback function to perform a set of write
2428          * queries. If a deadlock occurs during the processing, the transaction
2429          * will be rolled back and the callback function will be called again.
2430          *
2431          * Avoid using this method outside of Job or Maintenance classes.
2432          *
2433          * Usage:
2434          *   $dbw->deadlockLoop( callback, ... );
2435          *
2436          * Extra arguments are passed through to the specified callback function.
2437          * This method requires that no transactions are already active to avoid
2438          * causing premature commits or exceptions.
2439          *
2440          * Returns whatever the callback function returned on its successful,
2441          * iteration, or false on error, for example if the retry limit was
2442          * reached.
2443          *
2444          * @return mixed
2445          * @throws DBUnexpectedError
2446          * @throws Exception
2447          */
2448         public function deadlockLoop() {
2449                 $args = func_get_args();
2450                 $function = array_shift( $args );
2451                 $tries = self::DEADLOCK_TRIES;
2452
2453                 $this->begin( __METHOD__ );
2454
2455                 $retVal = null;
2456                 /** @var Exception $e */
2457                 $e = null;
2458                 do {
2459                         try {
2460                                 $retVal = call_user_func_array( $function, $args );
2461                                 break;
2462                         } catch ( DBQueryError $e ) {
2463                                 if ( $this->wasDeadlock() ) {
2464                                         // Retry after a randomized delay
2465                                         usleep( mt_rand( self::DEADLOCK_DELAY_MIN, self::DEADLOCK_DELAY_MAX ) );
2466                                 } else {
2467                                         // Throw the error back up
2468                                         throw $e;
2469                                 }
2470                         }
2471                 } while ( --$tries > 0 );
2472
2473                 if ( $tries <= 0 ) {
2474                         // Too many deadlocks; give up
2475                         $this->rollback( __METHOD__ );
2476                         throw $e;
2477                 } else {
2478                         $this->commit( __METHOD__ );
2479
2480                         return $retVal;
2481                 }
2482         }
2483
2484         public function masterPosWait( DBMasterPos $pos, $timeout ) {
2485                 # Real waits are implemented in the subclass.
2486                 return 0;
2487         }
2488
2489         public function getSlavePos() {
2490                 # Stub
2491                 return false;
2492         }
2493
2494         public function getMasterPos() {
2495                 # Stub
2496                 return false;
2497         }
2498
2499         public function serverIsReadOnly() {
2500                 return false;
2501         }
2502
2503         final public function onTransactionResolution( callable $callback, $fname = __METHOD__ ) {
2504                 if ( !$this->mTrxLevel ) {
2505                         throw new DBUnexpectedError( $this, "No transaction is active." );
2506                 }
2507                 $this->mTrxEndCallbacks[] = [ $callback, $fname ];
2508         }
2509
2510         final public function onTransactionIdle( callable $callback, $fname = __METHOD__ ) {
2511                 $this->mTrxIdleCallbacks[] = [ $callback, $fname ];
2512                 if ( !$this->mTrxLevel ) {
2513                         $this->runOnTransactionIdleCallbacks( self::TRIGGER_IDLE );
2514                 }
2515         }
2516
2517         final public function onTransactionPreCommitOrIdle( callable $callback, $fname = __METHOD__ ) {
2518                 if ( $this->mTrxLevel ) {
2519                         $this->mTrxPreCommitCallbacks[] = [ $callback, $fname ];
2520                 } else {
2521                         // If no transaction is active, then make one for this callback
2522                         $this->startAtomic( __METHOD__ );
2523                         try {
2524                                 call_user_func( $callback );
2525                                 $this->endAtomic( __METHOD__ );
2526                         } catch ( Exception $e ) {
2527                                 $this->rollback( __METHOD__, self::FLUSHING_INTERNAL );
2528                                 throw $e;
2529                         }
2530                 }
2531         }
2532
2533         final public function setTransactionListener( $name, callable $callback = null ) {
2534                 if ( $callback ) {
2535                         $this->mTrxRecurringCallbacks[$name] = $callback;
2536                 } else {
2537                         unset( $this->mTrxRecurringCallbacks[$name] );
2538                 }
2539         }
2540
2541         /**
2542          * Whether to disable running of post-COMMIT/ROLLBACK callbacks
2543          *
2544          * This method should not be used outside of Database/LoadBalancer
2545          *
2546          * @param bool $suppress
2547          * @since 1.28
2548          */
2549         final public function setTrxEndCallbackSuppression( $suppress ) {
2550                 $this->mTrxEndCallbacksSuppressed = $suppress;
2551         }
2552
2553         /**
2554          * Actually run and consume any "on transaction idle/resolution" callbacks.
2555          *
2556          * This method should not be used outside of Database/LoadBalancer
2557          *
2558          * @param integer $trigger IDatabase::TRIGGER_* constant
2559          * @since 1.20
2560          * @throws Exception
2561          */
2562         public function runOnTransactionIdleCallbacks( $trigger ) {
2563                 if ( $this->mTrxEndCallbacksSuppressed ) {
2564                         return;
2565                 }
2566
2567                 $autoTrx = $this->getFlag( DBO_TRX ); // automatic begin() enabled?
2568                 /** @var Exception $e */
2569                 $e = null; // first exception
2570                 do { // callbacks may add callbacks :)
2571                         $callbacks = array_merge(
2572                                 $this->mTrxIdleCallbacks,
2573                                 $this->mTrxEndCallbacks // include "transaction resolution" callbacks
2574                         );
2575                         $this->mTrxIdleCallbacks = []; // consumed (and recursion guard)
2576                         $this->mTrxEndCallbacks = []; // consumed (recursion guard)
2577                         foreach ( $callbacks as $callback ) {
2578                                 try {
2579                                         list( $phpCallback ) = $callback;
2580                                         $this->clearFlag( DBO_TRX ); // make each query its own transaction
2581                                         call_user_func_array( $phpCallback, [ $trigger ] );
2582                                         if ( $autoTrx ) {
2583                                                 $this->setFlag( DBO_TRX ); // restore automatic begin()
2584                                         } else {
2585                                                 $this->clearFlag( DBO_TRX ); // restore auto-commit
2586                                         }
2587                                 } catch ( Exception $ex ) {
2588                                         call_user_func( $this->errorLogger, $ex );
2589                                         $e = $e ?: $ex;
2590                                         // Some callbacks may use startAtomic/endAtomic, so make sure
2591                                         // their transactions are ended so other callbacks don't fail
2592                                         if ( $this->trxLevel() ) {
2593                                                 $this->rollback( __METHOD__, self::FLUSHING_INTERNAL );
2594                                         }
2595                                 }
2596                         }
2597                 } while ( count( $this->mTrxIdleCallbacks ) );
2598
2599                 if ( $e instanceof Exception ) {
2600                         throw $e; // re-throw any first exception
2601                 }
2602         }
2603
2604         /**
2605          * Actually run and consume any "on transaction pre-commit" callbacks.
2606          *
2607          * This method should not be used outside of Database/LoadBalancer
2608          *
2609          * @since 1.22
2610          * @throws Exception
2611          */
2612         public function runOnTransactionPreCommitCallbacks() {
2613                 $e = null; // first exception
2614                 do { // callbacks may add callbacks :)
2615                         $callbacks = $this->mTrxPreCommitCallbacks;
2616                         $this->mTrxPreCommitCallbacks = []; // consumed (and recursion guard)
2617                         foreach ( $callbacks as $callback ) {
2618                                 try {
2619                                         list( $phpCallback ) = $callback;
2620                                         call_user_func( $phpCallback );
2621                                 } catch ( Exception $ex ) {
2622                                         call_user_func( $this->errorLogger, $ex );
2623                                         $e = $e ?: $ex;
2624                                 }
2625                         }
2626                 } while ( count( $this->mTrxPreCommitCallbacks ) );
2627
2628                 if ( $e instanceof Exception ) {
2629                         throw $e; // re-throw any first exception
2630                 }
2631         }
2632
2633         /**
2634          * Actually run any "transaction listener" callbacks.
2635          *
2636          * This method should not be used outside of Database/LoadBalancer
2637          *
2638          * @param integer $trigger IDatabase::TRIGGER_* constant
2639          * @throws Exception
2640          * @since 1.20
2641          */
2642         public function runTransactionListenerCallbacks( $trigger ) {
2643                 if ( $this->mTrxEndCallbacksSuppressed ) {
2644                         return;
2645                 }
2646
2647                 /** @var Exception $e */
2648                 $e = null; // first exception
2649
2650                 foreach ( $this->mTrxRecurringCallbacks as $phpCallback ) {
2651                         try {
2652                                 $phpCallback( $trigger, $this );
2653                         } catch ( Exception $ex ) {
2654                                 call_user_func( $this->errorLogger, $ex );
2655                                 $e = $e ?: $ex;
2656                         }
2657                 }
2658
2659                 if ( $e instanceof Exception ) {
2660                         throw $e; // re-throw any first exception
2661                 }
2662         }
2663
2664         final public function startAtomic( $fname = __METHOD__ ) {
2665                 if ( !$this->mTrxLevel ) {
2666                         $this->begin( $fname, self::TRANSACTION_INTERNAL );
2667                         // If DBO_TRX is set, a series of startAtomic/endAtomic pairs will result
2668                         // in all changes being in one transaction to keep requests transactional.
2669                         if ( !$this->getFlag( DBO_TRX ) ) {
2670                                 $this->mTrxAutomaticAtomic = true;
2671                         }
2672                 }
2673
2674                 $this->mTrxAtomicLevels[] = $fname;
2675         }
2676
2677         final public function endAtomic( $fname = __METHOD__ ) {
2678                 if ( !$this->mTrxLevel ) {
2679                         throw new DBUnexpectedError( $this, "No atomic transaction is open (got $fname)." );
2680                 }
2681                 if ( !$this->mTrxAtomicLevels ||
2682                         array_pop( $this->mTrxAtomicLevels ) !== $fname
2683                 ) {
2684                         throw new DBUnexpectedError( $this, "Invalid atomic section ended (got $fname)." );
2685                 }
2686
2687                 if ( !$this->mTrxAtomicLevels && $this->mTrxAutomaticAtomic ) {
2688                         $this->commit( $fname, self::FLUSHING_INTERNAL );
2689                 }
2690         }
2691
2692         final public function doAtomicSection( $fname, callable $callback ) {
2693                 $this->startAtomic( $fname );
2694                 try {
2695                         $res = call_user_func_array( $callback, [ $this, $fname ] );
2696                 } catch ( Exception $e ) {
2697                         $this->rollback( $fname, self::FLUSHING_INTERNAL );
2698                         throw $e;
2699                 }
2700                 $this->endAtomic( $fname );
2701
2702                 return $res;
2703         }
2704
2705         final public function begin( $fname = __METHOD__, $mode = self::TRANSACTION_EXPLICIT ) {
2706                 // Protect against mismatched atomic section, transaction nesting, and snapshot loss
2707                 if ( $this->mTrxLevel ) {
2708                         if ( $this->mTrxAtomicLevels ) {
2709                                 $levels = implode( ', ', $this->mTrxAtomicLevels );
2710                                 $msg = "$fname: Got explicit BEGIN while atomic section(s) $levels are open.";
2711                                 throw new DBUnexpectedError( $this, $msg );
2712                         } elseif ( !$this->mTrxAutomatic ) {
2713                                 $msg = "$fname: Explicit transaction already active (from {$this->mTrxFname}).";
2714                                 throw new DBUnexpectedError( $this, $msg );
2715                         } else {
2716                                 // @TODO: make this an exception at some point
2717                                 $msg = "$fname: Implicit transaction already active (from {$this->mTrxFname}).";
2718                                 $this->queryLogger->error( $msg );
2719                                 return; // join the main transaction set
2720                         }
2721                 } elseif ( $this->getFlag( DBO_TRX ) && $mode !== self::TRANSACTION_INTERNAL ) {
2722                         // @TODO: make this an exception at some point
2723                         $msg = "$fname: Implicit transaction expected (DBO_TRX set).";
2724                         $this->queryLogger->error( $msg );
2725                         return; // let any writes be in the main transaction
2726                 }
2727
2728                 // Avoid fatals if close() was called
2729                 $this->assertOpen();
2730
2731                 $this->doBegin( $fname );
2732                 $this->mTrxTimestamp = microtime( true );
2733                 $this->mTrxFname = $fname;
2734                 $this->mTrxDoneWrites = false;
2735                 $this->mTrxAutomatic = ( $mode === self::TRANSACTION_INTERNAL );
2736                 $this->mTrxAutomaticAtomic = false;
2737                 $this->mTrxAtomicLevels = [];
2738                 $this->mTrxShortId = sprintf( '%06x', mt_rand( 0, 0xffffff ) );
2739                 $this->mTrxWriteDuration = 0.0;
2740                 $this->mTrxWriteQueryCount = 0;
2741                 $this->mTrxWriteAdjDuration = 0.0;
2742                 $this->mTrxWriteAdjQueryCount = 0;
2743                 $this->mTrxWriteCallers = [];
2744                 // First SELECT after BEGIN will establish the snapshot in REPEATABLE-READ.
2745                 // Get an estimate of the replica DB lag before then, treating estimate staleness
2746                 // as lag itself just to be safe
2747                 $status = $this->getApproximateLagStatus();
2748                 $this->mTrxReplicaLag = $status['lag'] + ( microtime( true ) - $status['since'] );
2749         }
2750
2751         /**
2752          * Issues the BEGIN command to the database server.
2753          *
2754          * @see DatabaseBase::begin()
2755          * @param string $fname
2756          */
2757         protected function doBegin( $fname ) {
2758                 $this->query( 'BEGIN', $fname );
2759                 $this->mTrxLevel = 1;
2760         }
2761
2762         final public function commit( $fname = __METHOD__, $flush = '' ) {
2763                 if ( $this->mTrxLevel && $this->mTrxAtomicLevels ) {
2764                         // There are still atomic sections open. This cannot be ignored
2765                         $levels = implode( ', ', $this->mTrxAtomicLevels );
2766                         throw new DBUnexpectedError(
2767                                 $this,
2768                                 "$fname: Got COMMIT while atomic sections $levels are still open."
2769                         );
2770                 }
2771
2772                 if ( $flush === self::FLUSHING_INTERNAL || $flush === self::FLUSHING_ALL_PEERS ) {
2773                         if ( !$this->mTrxLevel ) {
2774                                 return; // nothing to do
2775                         } elseif ( !$this->mTrxAutomatic ) {
2776                                 throw new DBUnexpectedError(
2777                                         $this,
2778                                         "$fname: Flushing an explicit transaction, getting out of sync."
2779                                 );
2780                         }
2781                 } else {
2782                         if ( !$this->mTrxLevel ) {
2783                                 $this->queryLogger->error( "$fname: No transaction to commit, something got out of sync." );
2784                                 return; // nothing to do
2785                         } elseif ( $this->mTrxAutomatic ) {
2786                                 // @TODO: make this an exception at some point
2787                                 $msg = "$fname: Explicit commit of implicit transaction.";
2788                                 $this->queryLogger->error( $msg );
2789                                 return; // wait for the main transaction set commit round
2790                         }
2791                 }
2792
2793                 // Avoid fatals if close() was called
2794                 $this->assertOpen();
2795
2796                 $this->runOnTransactionPreCommitCallbacks();
2797                 $writeTime = $this->pendingWriteQueryDuration( self::ESTIMATE_DB_APPLY );
2798                 $this->doCommit( $fname );
2799                 if ( $this->mTrxDoneWrites ) {
2800                         $this->mDoneWrites = microtime( true );
2801                         $this->trxProfiler->transactionWritingOut(
2802                                 $this->mServer, $this->mDBname, $this->mTrxShortId, $writeTime );
2803                 }
2804
2805                 $this->runOnTransactionIdleCallbacks( self::TRIGGER_COMMIT );
2806                 $this->runTransactionListenerCallbacks( self::TRIGGER_COMMIT );
2807         }
2808
2809         /**
2810          * Issues the COMMIT command to the database server.
2811          *
2812          * @see DatabaseBase::commit()
2813          * @param string $fname
2814          */
2815         protected function doCommit( $fname ) {
2816                 if ( $this->mTrxLevel ) {
2817                         $this->query( 'COMMIT', $fname );
2818                         $this->mTrxLevel = 0;
2819                 }
2820         }
2821
2822         final public function rollback( $fname = __METHOD__, $flush = '' ) {
2823                 if ( $flush === self::FLUSHING_INTERNAL || $flush === self::FLUSHING_ALL_PEERS ) {
2824                         if ( !$this->mTrxLevel ) {
2825                                 return; // nothing to do
2826                         }
2827                 } else {
2828                         if ( !$this->mTrxLevel ) {
2829                                 $this->queryLogger->error(
2830                                         "$fname: No transaction to rollback, something got out of sync." );
2831                                 return; // nothing to do
2832                         } elseif ( $this->getFlag( DBO_TRX ) ) {
2833                                 throw new DBUnexpectedError(
2834                                         $this,
2835                                         "$fname: Expected mass rollback of all peer databases (DBO_TRX set)."
2836                                 );
2837                         }
2838                 }
2839
2840                 // Avoid fatals if close() was called
2841                 $this->assertOpen();
2842
2843                 $this->doRollback( $fname );
2844                 $this->mTrxAtomicLevels = [];
2845                 if ( $this->mTrxDoneWrites ) {
2846                         $this->trxProfiler->transactionWritingOut(
2847                                 $this->mServer, $this->mDBname, $this->mTrxShortId );
2848                 }
2849
2850                 $this->mTrxIdleCallbacks = []; // clear
2851                 $this->mTrxPreCommitCallbacks = []; // clear
2852                 $this->runOnTransactionIdleCallbacks( self::TRIGGER_ROLLBACK );
2853                 $this->runTransactionListenerCallbacks( self::TRIGGER_ROLLBACK );
2854         }
2855
2856         /**
2857          * Issues the ROLLBACK command to the database server.
2858          *
2859          * @see DatabaseBase::rollback()
2860          * @param string $fname
2861          */
2862         protected function doRollback( $fname ) {
2863                 if ( $this->mTrxLevel ) {
2864                         # Disconnects cause rollback anyway, so ignore those errors
2865                         $ignoreErrors = true;
2866                         $this->query( 'ROLLBACK', $fname, $ignoreErrors );
2867                         $this->mTrxLevel = 0;
2868                 }
2869         }
2870
2871         public function flushSnapshot( $fname = __METHOD__ ) {
2872                 if ( $this->writesOrCallbacksPending() || $this->explicitTrxActive() ) {
2873                         // This only flushes transactions to clear snapshots, not to write data
2874                         $fnames = implode( ', ', $this->pendingWriteAndCallbackCallers() );
2875                         throw new DBUnexpectedError(
2876                                 $this,
2877                                 "$fname: Cannot COMMIT to clear snapshot because writes are pending ($fnames)."
2878                         );
2879                 }
2880
2881                 $this->commit( $fname, self::FLUSHING_INTERNAL );
2882         }
2883
2884         public function explicitTrxActive() {
2885                 return $this->mTrxLevel && ( $this->mTrxAtomicLevels || !$this->mTrxAutomatic );
2886         }
2887
2888         /**
2889          * Creates a new table with structure copied from existing table
2890          * Note that unlike most database abstraction functions, this function does not
2891          * automatically append database prefix, because it works at a lower
2892          * abstraction level.
2893          * The table names passed to this function shall not be quoted (this
2894          * function calls addIdentifierQuotes when needed).
2895          *
2896          * @param string $oldName Name of table whose structure should be copied
2897          * @param string $newName Name of table to be created
2898          * @param bool $temporary Whether the new table should be temporary
2899          * @param string $fname Calling function name
2900          * @throws RuntimeException
2901          * @return bool True if operation was successful
2902          */
2903         public function duplicateTableStructure( $oldName, $newName, $temporary = false,
2904                 $fname = __METHOD__
2905         ) {
2906                 throw new RuntimeException( __METHOD__ . ' is not implemented in descendant class' );
2907         }
2908
2909         function listTables( $prefix = null, $fname = __METHOD__ ) {
2910                 throw new RuntimeException( __METHOD__ . ' is not implemented in descendant class' );
2911         }
2912
2913         /**
2914          * Reset the views process cache set by listViews()
2915          * @since 1.22
2916          */
2917         final public function clearViewsCache() {
2918                 $this->allViews = null;
2919         }
2920
2921         /**
2922          * Lists all the VIEWs in the database
2923          *
2924          * For caching purposes the list of all views should be stored in
2925          * $this->allViews. The process cache can be cleared with clearViewsCache()
2926          *
2927          * @param string $prefix Only show VIEWs with this prefix, eg. unit_test_
2928          * @param string $fname Name of calling function
2929          * @throws RuntimeException
2930          * @return array
2931          * @since 1.22
2932          */
2933         public function listViews( $prefix = null, $fname = __METHOD__ ) {
2934                 throw new RuntimeException( __METHOD__ . ' is not implemented in descendant class' );
2935         }
2936
2937         /**
2938          * Differentiates between a TABLE and a VIEW
2939          *
2940          * @param string $name Name of the database-structure to test.
2941          * @throws RuntimeException
2942          * @return bool
2943          * @since 1.22
2944          */
2945         public function isView( $name ) {
2946                 throw new RuntimeException( __METHOD__ . ' is not implemented in descendant class' );
2947         }
2948
2949         public function timestamp( $ts = 0 ) {
2950                 $t = new ConvertableTimestamp( $ts );
2951                 // Let errors bubble up to avoid putting garbage in the DB
2952                 return $t->getTimestamp( TS_MW );
2953         }
2954
2955         public function timestampOrNull( $ts = null ) {
2956                 if ( is_null( $ts ) ) {
2957                         return null;
2958                 } else {
2959                         return $this->timestamp( $ts );
2960                 }
2961         }
2962
2963         /**
2964          * Take the result from a query, and wrap it in a ResultWrapper if
2965          * necessary. Boolean values are passed through as is, to indicate success
2966          * of write queries or failure.
2967          *
2968          * Once upon a time, DatabaseBase::query() returned a bare MySQL result
2969          * resource, and it was necessary to call this function to convert it to
2970          * a wrapper. Nowadays, raw database objects are never exposed to external
2971          * callers, so this is unnecessary in external code.
2972          *
2973          * @param bool|ResultWrapper|resource|object $result
2974          * @return bool|ResultWrapper
2975          */
2976         protected function resultObject( $result ) {
2977                 if ( !$result ) {
2978                         return false;
2979                 } elseif ( $result instanceof ResultWrapper ) {
2980                         return $result;
2981                 } elseif ( $result === true ) {
2982                         // Successful write query
2983                         return $result;
2984                 } else {
2985                         return new ResultWrapper( $this, $result );
2986                 }
2987         }
2988
2989         public function ping( &$rtt = null ) {
2990                 // Avoid hitting the server if it was hit recently
2991                 if ( $this->isOpen() && ( microtime( true ) - $this->lastPing ) < self::PING_TTL ) {
2992                         if ( !func_num_args() || $this->mRTTEstimate > 0 ) {
2993                                 $rtt = $this->mRTTEstimate;
2994                                 return true; // don't care about $rtt
2995                         }
2996                 }
2997
2998                 // This will reconnect if possible or return false if not
2999                 $this->clearFlag( DBO_TRX, self::REMEMBER_PRIOR );
3000                 $ok = ( $this->query( self::PING_QUERY, __METHOD__, true ) !== false );
3001                 $this->restoreFlags( self::RESTORE_PRIOR );
3002
3003                 if ( $ok ) {
3004                         $rtt = $this->mRTTEstimate;
3005                 }
3006
3007                 return $ok;
3008         }
3009
3010         /**
3011          * @return bool
3012          */
3013         protected function reconnect() {
3014                 $this->closeConnection();
3015                 $this->mOpened = false;
3016                 $this->mConn = false;
3017                 try {
3018                         $this->open( $this->mServer, $this->mUser, $this->mPassword, $this->mDBname );
3019                         $this->lastPing = microtime( true );
3020                         $ok = true;
3021                 } catch ( DBConnectionError $e ) {
3022                         $ok = false;
3023                 }
3024
3025                 return $ok;
3026         }
3027
3028         public function getSessionLagStatus() {
3029                 return $this->getTransactionLagStatus() ?: $this->getApproximateLagStatus();
3030         }
3031
3032         /**
3033          * Get the replica DB lag when the current transaction started
3034          *
3035          * This is useful when transactions might use snapshot isolation
3036          * (e.g. REPEATABLE-READ in innodb), so the "real" lag of that data
3037          * is this lag plus transaction duration. If they don't, it is still
3038          * safe to be pessimistic. This returns null if there is no transaction.
3039          *
3040          * @return array|null ('lag': seconds or false on error, 'since': UNIX timestamp of BEGIN)
3041          * @since 1.27
3042          */
3043         public function getTransactionLagStatus() {
3044                 return $this->mTrxLevel
3045                         ? [ 'lag' => $this->mTrxReplicaLag, 'since' => $this->trxTimestamp() ]
3046                         : null;
3047         }
3048
3049         /**
3050          * Get a replica DB lag estimate for this server
3051          *
3052          * @return array ('lag': seconds or false on error, 'since': UNIX timestamp of estimate)
3053          * @since 1.27
3054          */
3055         public function getApproximateLagStatus() {
3056                 return [
3057                         'lag'   => $this->getLBInfo( 'replica' ) ? $this->getLag() : 0,
3058                         'since' => microtime( true )
3059                 ];
3060         }
3061
3062         /**
3063          * Merge the result of getSessionLagStatus() for several DBs
3064          * using the most pessimistic values to estimate the lag of
3065          * any data derived from them in combination
3066          *
3067          * This is information is useful for caching modules
3068          *
3069          * @see WANObjectCache::set()
3070          * @see WANObjectCache::getWithSetCallback()
3071          *
3072          * @param IDatabase $db1
3073          * @param IDatabase ...
3074          * @return array Map of values:
3075          *   - lag: highest lag of any of the DBs or false on error (e.g. replication stopped)
3076          *   - since: oldest UNIX timestamp of any of the DB lag estimates
3077          *   - pending: whether any of the DBs have uncommitted changes
3078          * @since 1.27
3079          */
3080         public static function getCacheSetOptions( IDatabase $db1 ) {
3081                 $res = [ 'lag' => 0, 'since' => INF, 'pending' => false ];
3082                 foreach ( func_get_args() as $db ) {
3083                         /** @var IDatabase $db */
3084                         $status = $db->getSessionLagStatus();
3085                         if ( $status['lag'] === false ) {
3086                                 $res['lag'] = false;
3087                         } elseif ( $res['lag'] !== false ) {
3088                                 $res['lag'] = max( $res['lag'], $status['lag'] );
3089                         }
3090                         $res['since'] = min( $res['since'], $status['since'] );
3091                         $res['pending'] = $res['pending'] ?: $db->writesPending();
3092                 }
3093
3094                 return $res;
3095         }
3096
3097         public function getLag() {
3098                 return 0;
3099         }
3100
3101         function maxListLen() {
3102                 return 0;
3103         }
3104
3105         public function encodeBlob( $b ) {
3106                 return $b;
3107         }
3108
3109         public function decodeBlob( $b ) {
3110                 if ( $b instanceof Blob ) {
3111                         $b = $b->fetch();
3112                 }
3113                 return $b;
3114         }
3115
3116         public function setSessionOptions( array $options ) {
3117         }
3118
3119         /**
3120          * Read and execute SQL commands from a file.
3121          *
3122          * Returns true on success, error string or exception on failure (depending
3123          * on object's error ignore settings).
3124          *
3125          * @param string $filename File name to open
3126          * @param bool|callable $lineCallback Optional function called before reading each line
3127          * @param bool|callable $resultCallback Optional function called for each MySQL result
3128          * @param bool|string $fname Calling function name or false if name should be
3129          *   generated dynamically using $filename
3130          * @param bool|callable $inputCallback Optional function called for each
3131          *   complete line sent
3132          * @return bool|string
3133          * @throws Exception
3134          */
3135         public function sourceFile(
3136                 $filename, $lineCallback = false, $resultCallback = false, $fname = false, $inputCallback = false
3137         ) {
3138                 MediaWiki\suppressWarnings();
3139                 $fp = fopen( $filename, 'r' );
3140                 MediaWiki\restoreWarnings();
3141
3142                 if ( false === $fp ) {
3143                         throw new RuntimeException( "Could not open \"{$filename}\".\n" );
3144                 }
3145
3146                 if ( !$fname ) {
3147                         $fname = __METHOD__ . "( $filename )";
3148                 }
3149
3150                 try {
3151                         $error = $this->sourceStream( $fp, $lineCallback, $resultCallback, $fname, $inputCallback );
3152                 } catch ( Exception $e ) {
3153                         fclose( $fp );
3154                         throw $e;
3155                 }
3156
3157                 fclose( $fp );
3158
3159                 return $error;
3160         }
3161
3162         public function setSchemaVars( $vars ) {
3163                 $this->mSchemaVars = $vars;
3164         }
3165
3166         /**
3167          * Read and execute commands from an open file handle.
3168          *
3169          * Returns true on success, error string or exception on failure (depending
3170          * on object's error ignore settings).
3171          *
3172          * @param resource $fp File handle
3173          * @param bool|callable $lineCallback Optional function called before reading each query
3174          * @param bool|callable $resultCallback Optional function called for each MySQL result
3175          * @param string $fname Calling function name
3176          * @param bool|callable $inputCallback Optional function called for each complete query sent
3177          * @return bool|string
3178          */
3179         public function sourceStream( $fp, $lineCallback = false, $resultCallback = false,
3180                 $fname = __METHOD__, $inputCallback = false
3181         ) {
3182                 $cmd = '';
3183
3184                 while ( !feof( $fp ) ) {
3185                         if ( $lineCallback ) {
3186                                 call_user_func( $lineCallback );
3187                         }
3188
3189                         $line = trim( fgets( $fp ) );
3190
3191                         if ( $line == '' ) {
3192                                 continue;
3193                         }
3194
3195                         if ( '-' == $line[0] && '-' == $line[1] ) {
3196                                 continue;
3197                         }
3198
3199                         if ( $cmd != '' ) {
3200                                 $cmd .= ' ';
3201                         }
3202
3203                         $done = $this->streamStatementEnd( $cmd, $line );
3204
3205                         $cmd .= "$line\n";
3206
3207                         if ( $done || feof( $fp ) ) {
3208                                 $cmd = $this->replaceVars( $cmd );
3209
3210                                 if ( ( $inputCallback && call_user_func( $inputCallback, $cmd ) ) || !$inputCallback ) {
3211                                         $res = $this->query( $cmd, $fname );
3212
3213                                         if ( $resultCallback ) {
3214                                                 call_user_func( $resultCallback, $res, $this );
3215                                         }
3216
3217                                         if ( false === $res ) {
3218                                                 $err = $this->lastError();
3219
3220                                                 return "Query \"{$cmd}\" failed with error code \"$err\".\n";
3221                                         }
3222                                 }
3223                                 $cmd = '';
3224                         }
3225                 }
3226
3227                 return true;
3228         }
3229
3230         /**
3231          * Called by sourceStream() to check if we've reached a statement end
3232          *
3233          * @param string $sql SQL assembled so far
3234          * @param string $newLine New line about to be added to $sql
3235          * @return bool Whether $newLine contains end of the statement
3236          */
3237         public function streamStatementEnd( &$sql, &$newLine ) {
3238                 if ( $this->delimiter ) {
3239                         $prev = $newLine;
3240                         $newLine = preg_replace( '/' . preg_quote( $this->delimiter, '/' ) . '$/', '', $newLine );
3241                         if ( $newLine != $prev ) {
3242                                 return true;
3243                         }
3244                 }
3245
3246                 return false;
3247         }
3248
3249         /**
3250          * Database independent variable replacement. Replaces a set of variables
3251          * in an SQL statement with their contents as given by $this->getSchemaVars().
3252          *
3253          * Supports '{$var}' `{$var}` and / *$var* / (without the spaces) style variables.
3254          *
3255          * - '{$var}' should be used for text and is passed through the database's
3256          *   addQuotes method.
3257          * - `{$var}` should be used for identifiers (e.g. table and database names).
3258          *   It is passed through the database's addIdentifierQuotes method which
3259          *   can be overridden if the database uses something other than backticks.
3260          * - / *_* / or / *$wgDBprefix* / passes the name that follows through the
3261          *   database's tableName method.
3262          * - / *i* / passes the name that follows through the database's indexName method.
3263          * - In all other cases, / *$var* / is left unencoded. Except for table options,
3264          *   its use should be avoided. In 1.24 and older, string encoding was applied.
3265          *
3266          * @param string $ins SQL statement to replace variables in
3267          * @return string The new SQL statement with variables replaced
3268          */
3269         protected function replaceVars( $ins ) {
3270                 $vars = $this->getSchemaVars();
3271                 return preg_replace_callback(
3272                         '!
3273                                 /\* (\$wgDBprefix|[_i]) \*/ (\w*) | # 1-2. tableName, indexName
3274                                 \'\{\$ (\w+) }\'                  | # 3. addQuotes
3275                                 `\{\$ (\w+) }`                    | # 4. addIdentifierQuotes
3276                                 /\*\$ (\w+) \*/                     # 5. leave unencoded
3277                         !x',
3278                         function ( $m ) use ( $vars ) {
3279                                 // Note: Because of <https://bugs.php.net/bug.php?id=51881>,
3280                                 // check for both nonexistent keys *and* the empty string.
3281                                 if ( isset( $m[1] ) && $m[1] !== '' ) {
3282                                         if ( $m[1] === 'i' ) {
3283                                                 return $this->indexName( $m[2] );
3284                                         } else {
3285                                                 return $this->tableName( $m[2] );
3286                                         }
3287                                 } elseif ( isset( $m[3] ) && $m[3] !== '' && array_key_exists( $m[3], $vars ) ) {
3288                                         return $this->addQuotes( $vars[$m[3]] );
3289                                 } elseif ( isset( $m[4] ) && $m[4] !== '' && array_key_exists( $m[4], $vars ) ) {
3290                                         return $this->addIdentifierQuotes( $vars[$m[4]] );
3291                                 } elseif ( isset( $m[5] ) && $m[5] !== '' && array_key_exists( $m[5], $vars ) ) {
3292                                         return $vars[$m[5]];
3293                                 } else {
3294                                         return $m[0];
3295                                 }
3296                         },
3297                         $ins
3298                 );
3299         }
3300
3301         /**
3302          * Get schema variables. If none have been set via setSchemaVars(), then
3303          * use some defaults from the current object.
3304          *
3305          * @return array
3306          */
3307         protected function getSchemaVars() {
3308                 if ( $this->mSchemaVars ) {
3309                         return $this->mSchemaVars;
3310                 } else {
3311                         return $this->getDefaultSchemaVars();
3312                 }
3313         }
3314
3315         /**
3316          * Get schema variables to use if none have been set via setSchemaVars().
3317          *
3318          * Override this in derived classes to provide variables for tables.sql
3319          * and SQL patch files.
3320          *
3321          * @return array
3322          */
3323         protected function getDefaultSchemaVars() {
3324                 return [];
3325         }
3326
3327         public function lockIsFree( $lockName, $method ) {
3328                 return true;
3329         }
3330
3331         public function lock( $lockName, $method, $timeout = 5 ) {
3332                 $this->mNamedLocksHeld[$lockName] = 1;
3333
3334                 return true;
3335         }
3336
3337         public function unlock( $lockName, $method ) {
3338                 unset( $this->mNamedLocksHeld[$lockName] );
3339
3340                 return true;
3341         }
3342
3343         public function getScopedLockAndFlush( $lockKey, $fname, $timeout ) {
3344                 if ( $this->writesOrCallbacksPending() ) {
3345                         // This only flushes transactions to clear snapshots, not to write data
3346                         $fnames = implode( ', ', $this->pendingWriteAndCallbackCallers() );
3347                         throw new DBUnexpectedError(
3348                                 $this,
3349                                 "$fname: Cannot COMMIT to clear snapshot because writes are pending ($fnames)."
3350                         );
3351                 }
3352
3353                 if ( !$this->lock( $lockKey, $fname, $timeout ) ) {
3354                         return null;
3355                 }
3356
3357                 $unlocker = new ScopedCallback( function () use ( $lockKey, $fname ) {
3358                         if ( $this->trxLevel() ) {
3359                                 // There is a good chance an exception was thrown, causing any early return
3360                                 // from the caller. Let any error handler get a chance to issue rollback().
3361                                 // If there isn't one, let the error bubble up and trigger server-side rollback.
3362                                 $this->onTransactionResolution(
3363                                         function () use ( $lockKey, $fname ) {
3364                                                 $this->unlock( $lockKey, $fname );
3365                                         },
3366                                         $fname
3367                                 );
3368                         } else {
3369                                 $this->unlock( $lockKey, $fname );
3370                         }
3371                 } );
3372
3373                 $this->commit( $fname, self::FLUSHING_INTERNAL );
3374
3375                 return $unlocker;
3376         }
3377
3378         public function namedLocksEnqueue() {
3379                 return false;
3380         }
3381
3382         /**
3383          * Lock specific tables
3384          *
3385          * @param array $read Array of tables to lock for read access
3386          * @param array $write Array of tables to lock for write access
3387          * @param string $method Name of caller
3388          * @param bool $lowPriority Whether to indicate writes to be LOW PRIORITY
3389          * @return bool
3390          */
3391         public function lockTables( $read, $write, $method, $lowPriority = true ) {
3392                 return true;
3393         }
3394
3395         /**
3396          * Unlock specific tables
3397          *
3398          * @param string $method The caller
3399          * @return bool
3400          */
3401         public function unlockTables( $method ) {
3402                 return true;
3403         }
3404
3405         /**
3406          * Delete a table
3407          * @param string $tableName
3408          * @param string $fName
3409          * @return bool|ResultWrapper
3410          * @since 1.18
3411          */
3412         public function dropTable( $tableName, $fName = __METHOD__ ) {
3413                 if ( !$this->tableExists( $tableName, $fName ) ) {
3414                         return false;
3415                 }
3416                 $sql = "DROP TABLE " . $this->tableName( $tableName ) . " CASCADE";
3417
3418                 return $this->query( $sql, $fName );
3419         }
3420
3421         public function getInfinity() {
3422                 return 'infinity';
3423         }
3424
3425         public function encodeExpiry( $expiry ) {
3426                 return ( $expiry == '' || $expiry == 'infinity' || $expiry == $this->getInfinity() )
3427                         ? $this->getInfinity()
3428                         : $this->timestamp( $expiry );
3429         }
3430
3431         public function decodeExpiry( $expiry, $format = TS_MW ) {
3432                 if ( $expiry == '' || $expiry == 'infinity' || $expiry == $this->getInfinity() ) {
3433                         return 'infinity';
3434                 }
3435
3436                 try {
3437                         $t = new ConvertableTimestamp( $expiry );
3438
3439                         return $t->getTimestamp( $format );
3440                 } catch ( TimestampException $e ) {
3441                         return false;
3442                 }
3443         }
3444
3445         public function setBigSelects( $value = true ) {
3446                 // no-op
3447         }
3448
3449         public function isReadOnly() {
3450                 return ( $this->getReadOnlyReason() !== false );
3451         }
3452
3453         /**
3454          * @return string|bool Reason this DB is read-only or false if it is not
3455          */
3456         protected function getReadOnlyReason() {
3457                 $reason = $this->getLBInfo( 'readOnlyReason' );
3458
3459                 return is_string( $reason ) ? $reason : false;
3460         }
3461
3462         public function setTableAliases( array $aliases ) {
3463                 $this->tableAliases = $aliases;
3464         }
3465
3466         /**
3467          * @since 1.19
3468          * @return string
3469          */
3470         public function __toString() {
3471                 return (string)$this->mConn;
3472         }
3473
3474         /**
3475          * Called by serialize. Throw an exception when DB connection is serialized.
3476          * This causes problems on some database engines because the connection is
3477          * not restored on unserialize.
3478          */
3479         public function __sleep() {
3480                 throw new RuntimeException( 'Database serialization may cause problems, since ' .
3481                         'the connection is not restored on wakeup.' );
3482         }
3483
3484         /**
3485          * Run a few simple sanity checks
3486          */
3487         public function __destruct() {
3488                 if ( $this->mTrxLevel && $this->mTrxDoneWrites ) {
3489                         trigger_error( "Uncommitted DB writes (transaction from {$this->mTrxFname})." );
3490                 }
3491
3492                 $danglingWriters = $this->pendingWriteAndCallbackCallers();
3493                 if ( $danglingWriters ) {
3494                         $fnames = implode( ', ', $danglingWriters );
3495                         trigger_error( "DB transaction writes or callbacks still pending ($fnames)." );
3496                 }
3497         }
3498 }