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