includes/db/Database.php

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