includes/db/Database.php

   1 <?php
   2 /**
   3  * @defgroup Database Database
   4  *
   5  * This file deals with database interface functions
   6  * and query specifics/optimisations.
   7  *
   8  * This program is free software; you can redistribute it and/or modify
   9  * it under the terms of the GNU General Public License as published by
  10  * the Free Software Foundation; either version 2 of the License, or
  11  * (at your option) any later version.
  12  *
  13  * This program is distributed in the hope that it will be useful,
  14  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  15  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
  16  * GNU General Public License for more details.
  17  *
  18  * You should have received a copy of the GNU General Public License along
  19  * with this program; if not, write to the Free Software Foundation, Inc.,
  20  * 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
  21  * http://www.gnu.org/copyleft/gpl.html
  22  *
  23  * @file
  24  * @ingroup Database
  25  */
  26 use Psr\Log\LoggerAwareInterface;
  27 use Psr\Log\LoggerInterface;
  28
  29 /**
  30  * Database abstraction object
  31  * @ingroup Database
  32  */
  33 abstract class DatabaseBase implements IDatabase, LoggerAwareInterface {
  34         /** Number of times to re-try an operation in case of deadlock */
  35         const DEADLOCK_TRIES = 4;
  36         /** Minimum time to wait before retry, in microseconds */
  37         const DEADLOCK_DELAY_MIN = 500000;
  38         /** Maximum time to wait before retry */
  39         const DEADLOCK_DELAY_MAX = 1500000;
  40
  41         /** How long before it is worth doing a dummy query to test the connection */
  42         const PING_TTL = 1.0;
  43         const PING_QUERY = 'SELECT 1 AS ping';
  44
  45         const TINY_WRITE_SEC = .010;
  46         const SLOW_WRITE_SEC = .500;
  47         const SMALL_WRITE_ROWS = 100;
  48
  49         /** @var string SQL query */
  50         protected $mLastQuery = '';
  51         /** @var bool */
  52         protected $mDoneWrites = false;
  53         /** @var string|bool */
  54         protected $mPHPError = false;
  55         /** @var string */
  56         protected $mServer;
  57         /** @var string */
  58         protected $mUser;
  59         /** @var string */
  60         protected $mPassword;
  61         /** @var string */
  62         protected $mDBname;
  63         /** @var array[] $aliases Map of (table => (dbname, schema, prefix) map) */
  64         protected $tableAliases = [];
  65         /** @var bool Whether this PHP instance is for a CLI script */
  66         protected $cliMode;
  67         /** @var string Agent name for query profiling */
  68         protected $agent;
  69
  70         /** @var BagOStuff APC cache */
  71         protected $srvCache;
  72         /** @var LoggerInterface */
  73         protected $connLogger;
  74         /** @var LoggerInterface */
  75         protected $queryLogger;
  76         /** @var callback Error logging callback */
  77         protected $errorLogger;
  78
  79         /** @var resource Database connection */
  80         protected $mConn = null;
  81         /** @var bool */
  82         protected $mOpened = false;
  83
  84         /** @var array[] List of (callable, method name) */
  85         protected $mTrxIdleCallbacks = [];
  86         /** @var array[] List of (callable, method name) */
  87         protected $mTrxPreCommitCallbacks = [];
  88         /** @var array[] List of (callable, method name) */
  89         protected $mTrxEndCallbacks = [];
  90         /** @var callable[] Map of (name => callable) */
  91         protected $mTrxRecurringCallbacks = [];
  92         /** @var bool Whether to suppress triggering of transaction end callbacks */
  93         protected $mTrxEndCallbacksSuppressed = false;
  94
  95         /** @var string */
  96         protected $mTablePrefix;
  97         /** @var string */
  98         protected $mSchema;
  99         /** @var integer */
 100         protected $mFlags;
 101         /** @var array */
 102         protected $mLBInfo = [];
 103         /** @var bool|null */
 104         protected $mDefaultBigSelects = null;
 105         /** @var array|bool */
 106         protected $mSchemaVars = false;
 107         /** @var array */
 108         protected $mSessionVars = [];
 109         /** @var array|null */
 110         protected $preparedArgs;
 111         /** @var string|bool|null Stashed value of html_errors INI setting */
 112         protected $htmlErrors;
 113         /** @var string */
 114         protected $delimiter = ';';
 115
 116         /**
 117          * Either 1 if a transaction is active or 0 otherwise.
 118          * The other Trx fields may not be meaningfull if this is 0.
 119          *
 120          * @var int
 121          */
 122         protected $mTrxLevel = 0;
 123         /**
 124          * Either a short hexidecimal string if a transaction is active or ""
 125          *
 126          * @var string
 127          * @see DatabaseBase::mTrxLevel
 128          */
 129         protected $mTrxShortId = '';
 130         /**
 131          * The UNIX time that the transaction started. Callers can assume that if
 132          * snapshot isolation is used, then the data is *at least* up to date to that
 133          * point (possibly more up-to-date since the first SELECT defines the snapshot).
 134          *
 135          * @var float|null
 136          * @see DatabaseBase::mTrxLevel
 137          */
 138         private $mTrxTimestamp = null;
 139         /** @var float Lag estimate at the time of BEGIN */
 140         private $mTrxReplicaLag = null;
 141         /**
 142          * Remembers the function name given for starting the most recent transaction via begin().
 143          * Used to provide additional context for error reporting.
 144          *
 145          * @var string
 146          * @see DatabaseBase::mTrxLevel
 147          */
 148         private $mTrxFname = null;
 149         /**
 150          * Record if possible write queries were done in the last transaction started
 151          *
 152          * @var bool
 153          * @see DatabaseBase::mTrxLevel
 154          */
 155         private $mTrxDoneWrites = false;
 156         /**
 157          * Record if the current transaction was started implicitly due to DBO_TRX being set.
 158          *
 159          * @var bool
 160          * @see DatabaseBase::mTrxLevel
 161          */
 162         private $mTrxAutomatic = false;
 163         /**
 164          * Array of levels of atomicity within transactions
 165          *
 166          * @var array
 167          */
 168         private $mTrxAtomicLevels = [];
 169         /**
 170          * Record if the current transaction was started implicitly by DatabaseBase::startAtomic
 171          *
 172          * @var bool
 173          */
 174         private $mTrxAutomaticAtomic = false;
 175         /**
 176          * Track the write query callers of the current transaction
 177          *
 178          * @var string[]
 179          */
 180         private $mTrxWriteCallers = [];
 181         /**
 182          * @var float Seconds spent in write queries for the current transaction
 183          */
 184         private $mTrxWriteDuration = 0.0;
 185         /**
 186          * @var integer Number of write queries for the current transaction
 187          */
 188         private $mTrxWriteQueryCount = 0;
 189         /**
 190          * @var float Like mTrxWriteQueryCount but excludes lock-bound, easy to replicate, queries
 191          */
 192         private $mTrxWriteAdjDuration = 0.0;
 193         /**
 194          * @var integer Number of write queries counted in mTrxWriteAdjDuration
 195          */
 196         private $mTrxWriteAdjQueryCount = 0;
 197         /**
 198          * @var float RTT time estimate
 199          */
 200         private $mRTTEstimate = 0.0;
 201
 202         /** @var array Map of (name => 1) for locks obtained via lock() */
 203         private $mNamedLocksHeld = [];
 204
 205         /** @var IDatabase|null Lazy handle to the master DB this server replicates from */
 206         private $lazyMasterHandle;
 207
 208         /**
 209          * @since 1.21
 210          * @var resource File handle for upgrade
 211          */
 212         protected $fileHandle = null;
 213
 214         /**
 215          * @since 1.22
 216          * @var string[] Process cache of VIEWs names in the database
 217          */
 218         protected $allViews = null;
 219
 220         /** @var float UNIX timestamp */
 221         protected $lastPing = 0.0;
 222
 223         /** @var int[] Prior mFlags values */
 224         private $priorFlags = [];
 225
 226         /** @var Profiler */
 227         protected $profiler;
 228         /** @var TransactionProfiler */
 229         protected $trxProfiler;
 230
 231         /**
 232          * Constructor.
 233          *
 234          * FIXME: It is possible to construct a Database object with no associated
 235          * connection object, by specifying no parameters to __construct(). This
 236          * feature is deprecated and should be removed.
 237          *
 238          * IDatabase classes should not be constructed directly in external
 239          * code. DatabaseBase::factory() should be used instead.
 240          *
 241          * @param array $params Parameters passed from DatabaseBase::factory()
 242          */
 243         function __construct( array $params ) {
 244                 $server = $params['host'];
 245                 $user = $params['user'];
 246                 $password = $params['password'];
 247                 $dbName = $params['dbname'];
 248                 $flags = $params['flags'];
 249
 250                 $this->mSchema = $params['schema'];
 251                 $this->mTablePrefix = $params['tablePrefix'];
 252
 253                 $this->cliMode = isset( $params['cliMode'] )
 254                         ? $params['cliMode']
 255                         : ( PHP_SAPI === 'cli' );
 256                 $this->agent = isset( $params['agent'] )
 257                         ? str_replace( '/', '-', $params['agent'] ) // escape for comment
 258                         : '';
 259
 260                 $this->mFlags = $flags;
 261                 if ( $this->mFlags & DBO_DEFAULT ) {
 262                         if ( $this->cliMode ) {
 263                                 $this->mFlags &= ~DBO_TRX;
 264                         } else {
 265                                 $this->mFlags |= DBO_TRX;
 266                         }
 267                 }
 268
 269                 $this->mSessionVars = $params['variables'];
 270
 271                 $this->srvCache = isset( $params['srvCache'] )
 272                         ? $params['srvCache']
 273                         : new HashBagOStuff();
 274
 275                 $this->profiler = isset( $params['profiler'] )
 276                         ? $params['profiler']
 277                         : Profiler::instance(); // @TODO: remove global state
 278                 $this->trxProfiler = isset( $params['trxProfiler'] )
 279                         ? $params['trxProfiler']
 280                         : new TransactionProfiler();
 281                 $this->connLogger = isset( $params['connLogger'] )
 282                         ? $params['connLogger']
 283                         : new \Psr\Log\NullLogger();
 284                 $this->queryLogger = isset( $params['queryLogger'] )
 285                         ? $params['queryLogger']
 286                         : new \Psr\Log\NullLogger();
 287
 288                 if ( $user ) {
 289                         $this->open( $server, $user, $password, $dbName );
 290                 }
 291         }
 292
 293         /**
 294          * Given a DB type, construct the name of the appropriate child class of
 295          * IDatabase. This is designed to replace all of the manual stuff like:
 296          *    $class = 'Database' . ucfirst( strtolower( $dbType ) );
 297          * as well as validate against the canonical list of DB types we have
 298          *
 299          * This factory function is mostly useful for when you need to connect to a
 300          * database other than the MediaWiki default (such as for external auth,
 301          * an extension, et cetera). Do not use this to connect to the MediaWiki
 302          * database. Example uses in core:
 303          * @see LoadBalancer::reallyOpenConnection()
 304          * @see ForeignDBRepo::getMasterDB()
 305          * @see WebInstallerDBConnect::execute()
 306          *
 307          * @since 1.18
 308          *
 309          * @param string $dbType A possible DB type
 310          * @param array $p An array of options to pass to the constructor.
 311          *    Valid options are: host, user, password, dbname, flags, tablePrefix, schema, driver
 312          * @return IDatabase|null If the database driver or extension cannot be found
 313          * @throws InvalidArgumentException If the database driver or extension cannot be found
 314          */
 315         final public static function factory( $dbType, $p = [] ) {
 316                 $canonicalDBTypes = [
 317                         'mysql' => [ 'mysqli', 'mysql' ],
 318                         'postgres' => [],
 319                         'sqlite' => [],
 320                         'oracle' => [],
 321                         'mssql' => [],
 322                 ];
 323
 324                 $driver = false;
 325                 $dbType = strtolower( $dbType );
 326                 if ( isset( $canonicalDBTypes[$dbType] ) && $canonicalDBTypes[$dbType] ) {
 327                         $possibleDrivers = $canonicalDBTypes[$dbType];
 328                         if ( !empty( $p['driver'] ) ) {
 329                                 if ( in_array( $p['driver'], $possibleDrivers ) ) {
 330                                         $driver = $p['driver'];
 331                                 } else {
 332                                         throw new InvalidArgumentException( __METHOD__ .
 333                                                 " type '$dbType' does not support driver '{$p['driver']}'" );
 334                                 }
 335                         } else {
 336                                 foreach ( $possibleDrivers as $posDriver ) {
 337                                         if ( extension_loaded( $posDriver ) ) {
 338                                                 $driver = $posDriver;
 339                                                 break;
 340                                         }
 341                                 }
 342                         }
 343                 } else {
 344                         $driver = $dbType;
 345                 }
 346                 if ( $driver === false ) {
 347                         throw new InvalidArgumentException( __METHOD__ .
 348                                 " no viable database extension found for type '$dbType'" );
 349                 }
 350
 351                 // Determine schema defaults. Currently Microsoft SQL Server uses $wgDBmwschema,
 352                 // and everything else doesn't use a schema (e.g. null)
 353                 // Although postgres and oracle support schemas, we don't use them (yet)
 354                 // to maintain backwards compatibility
 355                 $defaultSchemas = [
 356                         'mssql' => 'get from global',
 357                 ];
 358
 359                 $class = 'Database' . ucfirst( $driver );
 360                 if ( class_exists( $class ) && is_subclass_of( $class, 'IDatabase' ) ) {
 361                         // Resolve some defaults for b/c
 362                         $p['host'] = isset( $p['host'] ) ? $p['host'] : false;
 363                         $p['user'] = isset( $p['user'] ) ? $p['user'] : false;
 364                         $p['password'] = isset( $p['password'] ) ? $p['password'] : false;
 365                         $p['dbname'] = isset( $p['dbname'] ) ? $p['dbname'] : false;
 366                         $p['flags'] = isset( $p['flags'] ) ? $p['flags'] : 0;
 367                         $p['variables'] = isset( $p['variables'] ) ? $p['variables'] : [];
 368                         $p['tablePrefix'] = isset( $p['tablePrefix'] ) ? $p['tablePrefix'] : '';
 369                         if ( !isset( $p['schema'] ) ) {
 370                                 $p['schema'] = isset( $defaultSchemas[$dbType] ) ? $defaultSchemas[$dbType] : null;
 371                         }
 372                         $p['foreign'] = isset( $p['foreign'] ) ? $p['foreign'] : false;
 373
 374                         $conn = new $class( $p );
 375                         if ( isset( $p['connLogger'] ) ) {
 376                                 $conn->connLogger = $p['connLogger'];
 377                         }
 378                         if ( isset( $p['queryLogger'] ) ) {
 379                                 $conn->queryLogger = $p['queryLogger'];
 380                         }
 381                         if ( isset( $p['errorLogger'] ) ) {
 382                                 $conn->errorLogger = $p['errorLogger'];
 383                         } else {
 384                                 $conn->errorLogger = function ( Exception $e ) {
 385                                         trigger_error( get_class( $e ) . ': ' . $e->getMessage(), E_WARNING );
 386                                 };
 387                         }
 388                 } else {
 389                         $conn = null;
 390                 }
 391
 392                 return $conn;
 393         }
 394
 395         public function setLogger( LoggerInterface $logger ) {
 396                 $this->queryLogger = $logger;
 397         }
 398
 399         public function getServerInfo() {
 400                 return $this->getServerVersion();
 401         }
 402
 403         /**
 404          * @return string Command delimiter used by this database engine
 405          */
 406         public function getDelimiter() {
 407                 return $this->delimiter;
 408         }
 409
 410         /**
 411          * Boolean, controls output of large amounts of debug information.
 412          * @param bool|null $debug
 413          *   - true to enable debugging
 414          *   - false to disable debugging
 415          *   - omitted or null to do nothing
 416          *
 417          * @return bool Previous value of the flag
 418          * @deprecated since 1.28; use setFlag()
 419          */
 420         public function debug( $debug = null ) {
 421                 $res = $this->getFlag( DBO_DEBUG );
 422                 if ( $debug !== null ) {
 423                         $debug ? $this->setFlag( DBO_DEBUG ) : $this->clearFlag( DBO_DEBUG );
 424                 }
 425
 426                 return $res;
 427         }
 428
 429         public function bufferResults( $buffer = null ) {
 430                 $res = !$this->getFlag( DBO_NOBUFFER );
 431                 if ( $buffer !== null ) {
 432                         $buffer ? $this->clearFlag( DBO_NOBUFFER ) : $this->setFlag( DBO_NOBUFFER );
 433                 }
 434
 435                 return $res;
 436         }
 437
 438         /**
 439          * Turns on (false) or off (true) the automatic generation and sending
 440          * of a "we're sorry, but there has been a database error" page on
 441          * database errors. Default is on (false). When turned off, the
 442          * code should use lastErrno() and lastError() to handle the
 443          * situation as appropriate.
 444          *
 445          * Do not use this function outside of the Database classes.
 446          *
 447          * @param null|bool $ignoreErrors
 448          * @return bool The previous value of the flag.
 449          */
 450         protected function ignoreErrors( $ignoreErrors = null ) {
 451                 $res = $this->getFlag( DBO_IGNORE );
 452                 if ( $ignoreErrors !== null ) {
 453                         $ignoreErrors ? $this->setFlag( DBO_IGNORE ) : $this->clearFlag( DBO_IGNORE );
 454                 }
 455
 456                 return $res;
 457         }
 458
 459         public function trxLevel() {
 460                 return $this->mTrxLevel;
 461         }
 462
 463         public function trxTimestamp() {
 464                 return $this->mTrxLevel ? $this->mTrxTimestamp : null;
 465         }
 466
 467         public function tablePrefix( $prefix = null ) {
 468                 $old = $this->mTablePrefix;
 469                 $this->mTablePrefix = $prefix;
 470
 471                 return $old;
 472         }
 473
 474         public function dbSchema( $schema = null ) {
 475                 $old = $this->mSchema;
 476                 $this->mSchema = $schema;
 477
 478                 return $old;
 479         }
 480
 481         /**
 482          * Set the filehandle to copy write statements to.
 483          *
 484          * @param resource $fh File handle
 485          */
 486         public function setFileHandle( $fh ) {
 487                 $this->fileHandle = $fh;
 488         }
 489
 490         public function getLBInfo( $name = null ) {
 491                 if ( is_null( $name ) ) {
 492                         return $this->mLBInfo;
 493                 } else {
 494                         if ( array_key_exists( $name, $this->mLBInfo ) ) {
 495                                 return $this->mLBInfo[$name];
 496                         } else {
 497                                 return null;
 498                         }
 499                 }
 500         }
 501
 502         public function setLBInfo( $name, $value = null ) {
 503                 if ( is_null( $value ) ) {
 504                         $this->mLBInfo = $name;
 505                 } else {
 506                         $this->mLBInfo[$name] = $value;
 507                 }
 508         }
 509
 510         public function setLazyMasterHandle( IDatabase $conn ) {
 511                 $this->lazyMasterHandle = $conn;
 512         }
 513
 514         /**
 515          * @return IDatabase|null
 516          * @see setLazyMasterHandle()
 517          * @since 1.27
 518          */
 519         public function getLazyMasterHandle() {
 520                 return $this->lazyMasterHandle;
 521         }
 522
 523         /**
 524          * @param TransactionProfiler $profiler
 525          * @since 1.27
 526          */
 527         public function setTransactionProfiler( TransactionProfiler $profiler ) {
 528                 $this->trxProfiler = $profiler;
 529         }
 530
 531         /**
 532          * Returns true if this database supports (and uses) cascading deletes
 533          *
 534          * @return bool
 535          */
 536         public function cascadingDeletes() {
 537                 return false;
 538         }
 539
 540         /**
 541          * Returns true if this database supports (and uses) triggers (e.g. on the page table)
 542          *
 543          * @return bool
 544          */
 545         public function cleanupTriggers() {
 546                 return false;
 547         }
 548
 549         /**
 550          * Returns true if this database is strict about what can be put into an IP field.
 551          * Specifically, it uses a NULL value instead of an empty string.
 552          *
 553          * @return bool
 554          */
 555         public function strictIPs() {
 556                 return false;
 557         }
 558
 559         /**
 560          * Returns true if this database uses timestamps rather than integers
 561          *
 562          * @return bool
 563          */
 564         public function realTimestamps() {
 565                 return false;
 566         }
 567
 568         public function implicitGroupby() {
 569                 return true;
 570         }
 571
 572         public function implicitOrderby() {
 573                 return true;
 574         }
 575
 576         /**
 577          * Returns true if this database can do a native search on IP columns
 578          * e.g. this works as expected: .. WHERE rc_ip = '127.42.12.102/32';
 579          *
 580          * @return bool
 581          */
 582         public function searchableIPs() {
 583                 return false;
 584         }
 585
 586         /**
 587          * Returns true if this database can use functional indexes
 588          *
 589          * @return bool
 590          */
 591         public function functionalIndexes() {
 592                 return false;
 593         }
 594
 595         public function lastQuery() {
 596                 return $this->mLastQuery;
 597         }
 598
 599         public function doneWrites() {
 600                 return (bool)$this->mDoneWrites;
 601         }
 602
 603         public function lastDoneWrites() {
 604                 return $this->mDoneWrites ?: false;
 605         }
 606
 607         public function writesPending() {
 608                 return $this->mTrxLevel && $this->mTrxDoneWrites;
 609         }
 610
 611         public function writesOrCallbacksPending() {
 612                 return $this->mTrxLevel && (
 613                         $this->mTrxDoneWrites || $this->mTrxIdleCallbacks || $this->mTrxPreCommitCallbacks
 614                 );
 615         }
 616
 617         public function pendingWriteQueryDuration( $type = self::ESTIMATE_TOTAL ) {
 618                 if ( !$this->mTrxLevel ) {
 619                         return false;
 620                 } elseif ( !$this->mTrxDoneWrites ) {
 621                         return 0.0;
 622                 }
 623
 624                 switch ( $type ) {
 625                         case self::ESTIMATE_DB_APPLY:
 626                                 $this->ping( $rtt );
 627                                 $rttAdjTotal = $this->mTrxWriteAdjQueryCount * $rtt;
 628                                 $applyTime = max( $this->mTrxWriteAdjDuration - $rttAdjTotal, 0 );
 629                                 // For omitted queries, make them count as something at least
 630                                 $omitted = $this->mTrxWriteQueryCount - $this->mTrxWriteAdjQueryCount;
 631                                 $applyTime += self::TINY_WRITE_SEC * $omitted;
 632
 633                                 return $applyTime;
 634                         default: // everything
 635                                 return $this->mTrxWriteDuration;
 636                 }
 637         }
 638
 639         public function pendingWriteCallers() {
 640                 return $this->mTrxLevel ? $this->mTrxWriteCallers : [];
 641         }
 642
 643         public function isOpen() {
 644                 return $this->mOpened;
 645         }
 646
 647         public function setFlag( $flag, $remember = self::REMEMBER_NOTHING ) {
 648                 if ( $remember === self::REMEMBER_PRIOR ) {
 649                         array_push( $this->priorFlags, $this->mFlags );
 650                 }
 651                 $this->mFlags |= $flag;
 652         }
 653
 654         public function clearFlag( $flag, $remember = self::REMEMBER_NOTHING ) {
 655                 if ( $remember === self::REMEMBER_PRIOR ) {
 656                         array_push( $this->priorFlags, $this->mFlags );
 657                 }
 658                 $this->mFlags &= ~$flag;
 659         }
 660
 661         public function restoreFlags( $state = self::RESTORE_PRIOR ) {
 662                 if ( !$this->priorFlags ) {
 663                         return;
 664                 }
 665
 666                 if ( $state === self::RESTORE_INITIAL ) {
 667                         $this->mFlags = reset( $this->priorFlags );
 668                         $this->priorFlags = [];
 669                 } else {
 670                         $this->mFlags = array_pop( $this->priorFlags );
 671                 }
 672         }
 673
 674         public function getFlag( $flag ) {
 675                 return !!( $this->mFlags & $flag );
 676         }
 677
 678         public function getProperty( $name ) {
 679                 return $this->$name;
 680         }
 681
 682         public function getWikiID() {
 683                 if ( $this->mTablePrefix ) {
 684                         return "{$this->mDBname}-{$this->mTablePrefix}";
 685                 } else {
 686                         return $this->mDBname;
 687                 }
 688         }
 689
 690         /**
 691          * Get information about an index into an object
 692          * @param string $table Table name
 693          * @param string $index Index name
 694          * @param string $fname Calling function name
 695          * @return mixed Database-specific index description class or false if the index does not exist
 696          */
 697         abstract function indexInfo( $table, $index, $fname = __METHOD__ );
 698
 699         /**
 700          * Wrapper for addslashes()
 701          *
 702          * @param string $s String to be slashed.
 703          * @return string Slashed string.
 704          */
 705         abstract function strencode( $s );
 706
 707         /**
 708          * Called by serialize. Throw an exception when DB connection is serialized.
 709          * This causes problems on some database engines because the connection is
 710          * not restored on unserialize.
 711          */
 712         public function __sleep() {
 713                 throw new RuntimeException( 'Database serialization may cause problems, since ' .
 714                         'the connection is not restored on wakeup.' );
 715         }
 716
 717         protected function installErrorHandler() {
 718                 $this->mPHPError = false;
 719                 $this->htmlErrors = ini_set( 'html_errors', '0' );
 720                 set_error_handler( [ $this, 'connectionerrorLogger' ] );
 721         }
 722
 723         /**
 724          * @return bool|string
 725          */
 726         protected function restoreErrorHandler() {
 727                 restore_error_handler();
 728                 if ( $this->htmlErrors !== false ) {
 729                         ini_set( 'html_errors', $this->htmlErrors );
 730                 }
 731                 if ( $this->mPHPError ) {
 732                         $error = preg_replace( '!\[<a.*</a>\]!', '', $this->mPHPError );
 733                         $error = preg_replace( '!^.*?:\s?(.*)$!', '$1', $error );
 734
 735                         return $error;
 736                 } else {
 737                         return false;
 738                 }
 739         }
 740
 741         /**
 742          * @param int $errno
 743          * @param string $errstr
 744          */
 745         public function connectionerrorLogger( $errno, $errstr ) {
 746                 $this->mPHPError = $errstr;
 747         }
 748
 749         /**
 750          * Create a log context to pass to PSR logging functions.
 751          *
 752          * @param array $extras Additional data to add to context
 753          * @return array
 754          */
 755         protected function getLogContext( array $extras = [] ) {
 756                 return array_merge(
 757                         [
 758                                 'db_server' => $this->mServer,
 759                                 'db_name' => $this->mDBname,
 760                                 'db_user' => $this->mUser,
 761                         ],
 762                         $extras
 763                 );
 764         }
 765
 766         public function close() {
 767                 if ( $this->mConn ) {
 768                         if ( $this->trxLevel() ) {
 769                                 $this->commit( __METHOD__, self::FLUSHING_INTERNAL );
 770                         }
 771
 772                         $closed = $this->closeConnection();
 773                         $this->mConn = false;
 774                 } elseif ( $this->mTrxIdleCallbacks || $this->mTrxEndCallbacks ) { // sanity
 775                         throw new RuntimeException( "Transaction callbacks still pending." );
 776                 } else {
 777                         $closed = true;
 778                 }
 779                 $this->mOpened = false;
 780
 781                 return $closed;
 782         }
 783
 784         /**
 785          * Make sure isOpen() returns true as a sanity check
 786          *
 787          * @throws DBUnexpectedError
 788          */
 789         protected function assertOpen() {
 790                 if ( !$this->isOpen() ) {
 791                         throw new DBUnexpectedError( $this, "DB connection was already closed." );
 792                 }
 793         }
 794
 795         /**
 796          * Closes underlying database connection
 797          * @since 1.20
 798          * @return bool Whether connection was closed successfully
 799          */
 800         abstract protected function closeConnection();
 801
 802         function reportConnectionError( $error = 'Unknown error' ) {
 803                 $myError = $this->lastError();
 804                 if ( $myError ) {
 805                         $error = $myError;
 806                 }
 807
 808                 # New method
 809                 throw new DBConnectionError( $this, $error );
 810         }
 811
 812         /**
 813          * The DBMS-dependent part of query()
 814          *
 815          * @param string $sql SQL query.
 816          * @return ResultWrapper|bool Result object to feed to fetchObject,
 817          *   fetchRow, ...; or false on failure
 818          */
 819         abstract protected function doQuery( $sql );
 820
 821         /**
 822          * Determine whether a query writes to the DB.
 823          * Should return true if unsure.
 824          *
 825          * @param string $sql
 826          * @return bool
 827          */
 828         protected function isWriteQuery( $sql ) {
 829                 return !preg_match(
 830                         '/^(?:SELECT|BEGIN|ROLLBACK|COMMIT|SET|SHOW|EXPLAIN|\(SELECT)\b/i', $sql );
 831         }
 832
 833         /**
 834          * @param $sql
 835          * @return string|null
 836          */
 837         protected function getQueryVerb( $sql ) {
 838                 return preg_match( '/^\s*([a-z]+)/i', $sql, $m ) ? strtoupper( $m[1] ) : null;
 839         }
 840
 841         /**
 842          * Determine whether a SQL statement is sensitive to isolation level.
 843          * A SQL statement is considered transactable if its result could vary
 844          * depending on the transaction isolation level. Operational commands
 845          * such as 'SET' and 'SHOW' are not considered to be transactable.
 846          *
 847          * @param string $sql
 848          * @return bool
 849          */
 850         protected function isTransactableQuery( $sql ) {
 851                 $verb = $this->getQueryVerb( $sql );
 852                 return !in_array( $verb, [ 'BEGIN', 'COMMIT', 'ROLLBACK', 'SHOW', 'SET' ], true );
 853         }
 854
 855         public function query( $sql, $fname = __METHOD__, $tempIgnore = false ) {
 856                 $priorWritesPending = $this->writesOrCallbacksPending();
 857                 $this->mLastQuery = $sql;
 858
 859                 $isWrite = $this->isWriteQuery( $sql );
 860                 if ( $isWrite ) {
 861                         $reason = $this->getReadOnlyReason();
 862                         if ( $reason !== false ) {
 863                                 throw new DBReadOnlyError( $this, "Database is read-only: $reason" );
 864                         }
 865                         # Set a flag indicating that writes have been done
 866                         $this->mDoneWrites = microtime( true );
 867                 }
 868
 869                 // Add trace comment to the begin of the sql string, right after the operator.
 870                 // Or, for one-word queries (like "BEGIN" or COMMIT") add it to the end (bug 42598)
 871                 $commentedSql = preg_replace( '/\s|$/', " /* $fname {$this->agent} */ ", $sql, 1 );
 872
 873                 # Start implicit transactions that wrap the request if DBO_TRX is enabled
 874                 if ( !$this->mTrxLevel && $this->getFlag( DBO_TRX )
 875                         && $this->isTransactableQuery( $sql )
 876                 ) {
 877                         $this->begin( __METHOD__ . " ($fname)", self::TRANSACTION_INTERNAL );
 878                         $this->mTrxAutomatic = true;
 879                 }
 880
 881                 # Keep track of whether the transaction has write queries pending
 882                 if ( $this->mTrxLevel && !$this->mTrxDoneWrites && $isWrite ) {
 883                         $this->mTrxDoneWrites = true;
 884                         $this->trxProfiler->transactionWritingIn(
 885                                 $this->mServer, $this->mDBname, $this->mTrxShortId );
 886                 }
 887
 888                 if ( $this->debug() ) {
 889                         $this->queryLogger->debug( "{$this->mDBname} {$commentedSql}" );
 890                 }
 891
 892                 # Avoid fatals if close() was called
 893                 $this->assertOpen();
 894
 895                 # Send the query to the server
 896                 $ret = $this->doProfiledQuery( $sql, $commentedSql, $isWrite, $fname );
 897
 898                 # Try reconnecting if the connection was lost
 899                 if ( false === $ret && $this->wasErrorReissuable() ) {
 900                         $recoverable = $this->canRecoverFromDisconnect( $sql, $priorWritesPending );
 901                         # Stash the last error values before anything might clear them
 902                         $lastError = $this->lastError();
 903                         $lastErrno = $this->lastErrno();
 904                         # Update state tracking to reflect transaction loss due to disconnection
 905                         $this->handleTransactionLoss();
 906                         if ( $this->reconnect() ) {
 907                                 $msg = __METHOD__ . ": lost connection to {$this->getServer()}; reconnected";
 908                                 $this->connLogger->warning( $msg );
 909                                 $this->queryLogger->warning(
 910                                         "$msg:\n" . ( new RuntimeException() )->getTraceAsString() );
 911
 912                                 if ( !$recoverable ) {
 913                                         # Callers may catch the exception and continue to use the DB
 914                                         $this->reportQueryError( $lastError, $lastErrno, $sql, $fname );
 915                                 } else {
 916                                         # Should be safe to silently retry the query
 917                                         $ret = $this->doProfiledQuery( $sql, $commentedSql, $isWrite, $fname );
 918                                 }
 919                         } else {
 920                                 $msg = __METHOD__ . ": lost connection to {$this->getServer()} permanently";
 921                                 $this->connLogger->error( $msg );
 922                         }
 923                 }
 924
 925                 if ( false === $ret ) {
 926                         # Deadlocks cause the entire transaction to abort, not just the statement.
 927                         # http://dev.mysql.com/doc/refman/5.7/en/innodb-error-handling.html
 928                         # https://www.postgresql.org/docs/9.1/static/explicit-locking.html
 929                         if ( $this->wasDeadlock() ) {
 930                                 if ( $this->explicitTrxActive() || $priorWritesPending ) {
 931                                         $tempIgnore = false; // not recoverable
 932                                 }
 933                                 # Update state tracking to reflect transaction loss
 934                                 $this->handleTransactionLoss();
 935                         }
 936
 937                         $this->reportQueryError(
 938                                 $this->lastError(), $this->lastErrno(), $sql, $fname, $tempIgnore );
 939                 }
 940
 941                 $res = $this->resultObject( $ret );
 942
 943                 return $res;
 944         }
 945
 946         private function doProfiledQuery( $sql, $commentedSql, $isWrite, $fname ) {
 947                 $isMaster = !is_null( $this->getLBInfo( 'master' ) );
 948                 # generalizeSQL() will probably cut down the query to reasonable
 949                 # logging size most of the time. The substr is really just a sanity check.
 950                 if ( $isMaster ) {
 951                         $queryProf = 'query-m: ' . substr( self::generalizeSQL( $sql ), 0, 255 );
 952                 } else {
 953                         $queryProf = 'query: ' . substr( self::generalizeSQL( $sql ), 0, 255 );
 954                 }
 955
 956                 # Include query transaction state
 957                 $queryProf .= $this->mTrxShortId ? " [TRX#{$this->mTrxShortId}]" : "";
 958
 959                 $startTime = microtime( true );
 960                 $this->profiler->profileIn( $queryProf );
 961                 $ret = $this->doQuery( $commentedSql );
 962                 $this->profiler->profileOut( $queryProf );
 963                 $queryRuntime = max( microtime( true ) - $startTime, 0.0 );
 964
 965                 unset( $queryProfSection ); // profile out (if set)
 966
 967                 if ( $ret !== false ) {
 968                         $this->lastPing = $startTime;
 969                         if ( $isWrite && $this->mTrxLevel ) {
 970                                 $this->updateTrxWriteQueryTime( $sql, $queryRuntime );
 971                                 $this->mTrxWriteCallers[] = $fname;
 972                         }
 973                 }
 974
 975                 if ( $sql === self::PING_QUERY ) {
 976                         $this->mRTTEstimate = $queryRuntime;
 977                 }
 978
 979                 $this->trxProfiler->recordQueryCompletion(
 980                         $queryProf, $startTime, $isWrite, $this->affectedRows()
 981                 );
 982                 MWDebug::query( $sql, $fname, $isMaster, $queryRuntime );
 983
 984                 return $ret;
 985         }
 986
 987         /**
 988          * Update the estimated run-time of a query, not counting large row lock times
 989          *
 990          * LoadBalancer can be set to rollback transactions that will create huge replication
 991          * lag. It bases this estimate off of pendingWriteQueryDuration(). Certain simple
 992          * queries, like inserting a row can take a long time due to row locking. This method
 993          * uses some simple heuristics to discount those cases.
 994          *
 995          * @param string $sql A SQL write query
 996          * @param float $runtime Total runtime, including RTT
 997          */
 998         private function updateTrxWriteQueryTime( $sql, $runtime ) {
 999                 // Whether this is indicative of replica DB runtime (except for RBR or ws_repl)
1000                 $indicativeOfReplicaRuntime = true;
1001                 if ( $runtime > self::SLOW_WRITE_SEC ) {
1002                         $verb = $this->getQueryVerb( $sql );
1003                         // insert(), upsert(), replace() are fast unless bulky in size or blocked on locks
1004                         if ( $verb === 'INSERT' ) {
1005                                 $indicativeOfReplicaRuntime = $this->affectedRows() > self::SMALL_WRITE_ROWS;
1006                         } elseif ( $verb === 'REPLACE' ) {
1007                                 $indicativeOfReplicaRuntime = $this->affectedRows() > self::SMALL_WRITE_ROWS / 2;
1008                         }
1009                 }
1010
1011                 $this->mTrxWriteDuration += $runtime;
1012                 $this->mTrxWriteQueryCount += 1;
1013                 if ( $indicativeOfReplicaRuntime ) {
1014                         $this->mTrxWriteAdjDuration += $runtime;
1015                         $this->mTrxWriteAdjQueryCount += 1;
1016                 }
1017         }
1018
1019         private function canRecoverFromDisconnect( $sql, $priorWritesPending ) {
1020                 # Transaction dropped; this can mean lost writes, or REPEATABLE-READ snapshots.
1021                 # Dropped connections also mean that named locks are automatically released.
1022                 # Only allow error suppression in autocommit mode or when the lost transaction
1023                 # didn't matter anyway (aside from DBO_TRX snapshot loss).
1024                 if ( $this->mNamedLocksHeld ) {
1025                         return false; // possible critical section violation
1026                 } elseif ( $sql === 'COMMIT' ) {
1027                         return !$priorWritesPending; // nothing written anyway? (T127428)
1028                 } elseif ( $sql === 'ROLLBACK' ) {
1029                         return true; // transaction lost...which is also what was requested :)
1030                 } elseif ( $this->explicitTrxActive() ) {
1031                         return false; // don't drop atomocity
1032                 } elseif ( $priorWritesPending ) {
1033                         return false; // prior writes lost from implicit transaction
1034                 }
1035
1036                 return true;
1037         }
1038
1039         private function handleTransactionLoss() {
1040                 $this->mTrxLevel = 0;
1041                 $this->mTrxIdleCallbacks = []; // bug 65263
1042                 $this->mTrxPreCommitCallbacks = []; // bug 65263
1043                 try {
1044                         // Handle callbacks in mTrxEndCallbacks
1045                         $this->runOnTransactionIdleCallbacks( self::TRIGGER_ROLLBACK );
1046                         $this->runTransactionListenerCallbacks( self::TRIGGER_ROLLBACK );
1047                         return null;
1048                 } catch ( Exception $e ) {
1049                         // Already logged; move on...
1050                         return $e;
1051                 }
1052         }
1053
1054         public function reportQueryError( $error, $errno, $sql, $fname, $tempIgnore = false ) {
1055                 if ( $this->ignoreErrors() || $tempIgnore ) {
1056                         $this->queryLogger->debug( "SQL ERROR (ignored): $error\n" );
1057                 } else {
1058                         $sql1line = mb_substr( str_replace( "\n", "\\n", $sql ), 0, 5 * 1024 );
1059                         $this->queryLogger->error(
1060                                 "{fname}\t{db_server}\t{errno}\t{error}\t{sql1line}",
1061                                 $this->getLogContext( [
1062                                         'method' => __METHOD__,
1063                                         'errno' => $errno,
1064                                         'error' => $error,
1065                                         'sql1line' => $sql1line,
1066                                         'fname' => $fname,
1067                                 ] )
1068                         );
1069                         $this->queryLogger->debug( "SQL ERROR: " . $error . "\n" );
1070                         throw new DBQueryError( $this, $error, $errno, $sql, $fname );
1071                 }
1072         }
1073
1074         /**
1075          * Intended to be compatible with the PEAR::DB wrapper functions.
1076          * http://pear.php.net/manual/en/package.database.db.intro-execute.php
1077          *
1078          * ? = scalar value, quoted as necessary
1079          * ! = raw SQL bit (a function for instance)
1080          * & = filename; reads the file and inserts as a blob
1081          *     (we don't use this though...)
1082          *
1083          * @param string $sql
1084          * @param string $func
1085          *
1086          * @return array
1087          */
1088         protected function prepare( $sql, $func = __METHOD__ ) {
1089                 /* MySQL doesn't support prepared statements (yet), so just
1090                  * pack up the query for reference. We'll manually replace
1091                  * the bits later.
1092                  */
1093                 return [ 'query' => $sql, 'func' => $func ];
1094         }
1095
1096         /**
1097          * Free a prepared query, generated by prepare().
1098          * @param string $prepared
1099          */
1100         protected function freePrepared( $prepared ) {
1101                 /* No-op by default */
1102         }
1103
1104         /**
1105          * Execute a prepared query with the various arguments
1106          * @param string $prepared The prepared sql
1107          * @param mixed $args Either an array here, or put scalars as varargs
1108          *
1109          * @return ResultWrapper
1110          */
1111         public function execute( $prepared, $args = null ) {
1112                 if ( !is_array( $args ) ) {
1113                         # Pull the var args
1114                         $args = func_get_args();
1115                         array_shift( $args );
1116                 }
1117
1118                 $sql = $this->fillPrepared( $prepared['query'], $args );
1119
1120                 return $this->query( $sql, $prepared['func'] );
1121         }
1122
1123         /**
1124          * For faking prepared SQL statements on DBs that don't support it directly.
1125          *
1126          * @param string $preparedQuery A 'preparable' SQL statement
1127          * @param array $args Array of Arguments to fill it with
1128          * @return string Executable SQL
1129          */
1130         public function fillPrepared( $preparedQuery, $args ) {
1131                 reset( $args );
1132                 $this->preparedArgs =& $args;
1133
1134                 return preg_replace_callback( '/(\\\\[?!&]|[?!&])/',
1135                         [ &$this, 'fillPreparedArg' ], $preparedQuery );
1136         }
1137
1138         /**
1139          * preg_callback func for fillPrepared()
1140          * The arguments should be in $this->preparedArgs and must not be touched
1141          * while we're doing this.
1142          *
1143          * @param array $matches
1144          * @throws DBUnexpectedError
1145          * @return string
1146          */
1147         protected function fillPreparedArg( $matches ) {
1148                 switch ( $matches[1] ) {
1149                         case '\\?':
1150                                 return '?';
1151                         case '\\!':
1152                                 return '!';
1153                         case '\\&':
1154                                 return '&';
1155                 }
1156
1157                 list( /* $n */, $arg ) = each( $this->preparedArgs );
1158
1159                 switch ( $matches[1] ) {
1160                         case '?':
1161                                 return $this->addQuotes( $arg );
1162                         case '!':
1163                                 return $arg;
1164                         case '&':
1165                                 # return $this->addQuotes( file_get_contents( $arg ) );
1166                                 throw new DBUnexpectedError(
1167                                         $this,
1168                                         '& mode is not implemented. If it\'s really needed, uncomment the line above.'
1169                                 );
1170                         default:
1171                                 throw new DBUnexpectedError(
1172                                         $this,
1173                                         'Received invalid match. This should never happen!'
1174                                 );
1175                 }
1176         }
1177
1178         public function freeResult( $res ) {
1179         }
1180
1181         public function selectField(
1182                 $table, $var, $cond = '', $fname = __METHOD__, $options = []
1183         ) {
1184                 if ( $var === '*' ) { // sanity
1185                         throw new DBUnexpectedError( $this, "Cannot use a * field: got '$var'" );
1186                 }
1187
1188                 if ( !is_array( $options ) ) {
1189                         $options = [ $options ];
1190                 }
1191
1192                 $options['LIMIT'] = 1;
1193
1194                 $res = $this->select( $table, $var, $cond, $fname, $options );
1195                 if ( $res === false || !$this->numRows( $res ) ) {
1196                         return false;
1197                 }
1198
1199                 $row = $this->fetchRow( $res );
1200
1201                 if ( $row !== false ) {
1202                         return reset( $row );
1203                 } else {
1204                         return false;
1205                 }
1206         }
1207
1208         public function selectFieldValues(
1209                 $table, $var, $cond = '', $fname = __METHOD__, $options = [], $join_conds = []
1210         ) {
1211                 if ( $var === '*' ) { // sanity
1212                         throw new DBUnexpectedError( $this, "Cannot use a * field" );
1213                 } elseif ( !is_string( $var ) ) { // sanity
1214                         throw new DBUnexpectedError( $this, "Cannot use an array of fields" );
1215                 }
1216
1217                 if ( !is_array( $options ) ) {
1218                         $options = [ $options ];
1219                 }
1220
1221                 $res = $this->select( $table, $var, $cond, $fname, $options, $join_conds );
1222                 if ( $res === false ) {
1223                         return false;
1224                 }
1225
1226                 $values = [];
1227                 foreach ( $res as $row ) {
1228                         $values[] = $row->$var;
1229                 }
1230
1231                 return $values;
1232         }
1233
1234         /**
1235          * Returns an optional USE INDEX clause to go after the table, and a
1236          * string to go at the end of the query.
1237          *
1238          * @param array $options Associative array of options to be turned into
1239          *   an SQL query, valid keys are listed in the function.
1240          * @return array
1241          * @see DatabaseBase::select()
1242          */
1243         public function makeSelectOptions( $options ) {
1244                 $preLimitTail = $postLimitTail = '';
1245                 $startOpts = '';
1246
1247                 $noKeyOptions = [];
1248
1249                 foreach ( $options as $key => $option ) {
1250                         if ( is_numeric( $key ) ) {
1251                                 $noKeyOptions[$option] = true;
1252                         }
1253                 }
1254
1255                 $preLimitTail .= $this->makeGroupByWithHaving( $options );
1256
1257                 $preLimitTail .= $this->makeOrderBy( $options );
1258
1259                 // if (isset($options['LIMIT'])) {
1260                 //      $tailOpts .= $this->limitResult('', $options['LIMIT'],
1261                 //              isset($options['OFFSET']) ? $options['OFFSET']
1262                 //              : false);
1263                 // }
1264
1265                 if ( isset( $noKeyOptions['FOR UPDATE'] ) ) {
1266                         $postLimitTail .= ' FOR UPDATE';
1267                 }
1268
1269                 if ( isset( $noKeyOptions['LOCK IN SHARE MODE'] ) ) {
1270                         $postLimitTail .= ' LOCK IN SHARE MODE';
1271                 }
1272
1273                 if ( isset( $noKeyOptions['DISTINCT'] ) || isset( $noKeyOptions['DISTINCTROW'] ) ) {
1274                         $startOpts .= 'DISTINCT';
1275                 }
1276
1277                 # Various MySQL extensions
1278                 if ( isset( $noKeyOptions['STRAIGHT_JOIN'] ) ) {
1279                         $startOpts .= ' /*! STRAIGHT_JOIN */';
1280                 }
1281
1282                 if ( isset( $noKeyOptions['HIGH_PRIORITY'] ) ) {
1283                         $startOpts .= ' HIGH_PRIORITY';
1284                 }
1285
1286                 if ( isset( $noKeyOptions['SQL_BIG_RESULT'] ) ) {
1287                         $startOpts .= ' SQL_BIG_RESULT';
1288                 }
1289
1290                 if ( isset( $noKeyOptions['SQL_BUFFER_RESULT'] ) ) {
1291                         $startOpts .= ' SQL_BUFFER_RESULT';
1292                 }
1293
1294                 if ( isset( $noKeyOptions['SQL_SMALL_RESULT'] ) ) {
1295                         $startOpts .= ' SQL_SMALL_RESULT';
1296                 }
1297
1298                 if ( isset( $noKeyOptions['SQL_CALC_FOUND_ROWS'] ) ) {
1299                         $startOpts .= ' SQL_CALC_FOUND_ROWS';
1300                 }
1301
1302                 if ( isset( $noKeyOptions['SQL_CACHE'] ) ) {
1303                         $startOpts .= ' SQL_CACHE';
1304                 }
1305
1306                 if ( isset( $noKeyOptions['SQL_NO_CACHE'] ) ) {
1307                         $startOpts .= ' SQL_NO_CACHE';
1308                 }
1309
1310                 if ( isset( $options['USE INDEX'] ) && is_string( $options['USE INDEX'] ) ) {
1311                         $useIndex = $this->useIndexClause( $options['USE INDEX'] );
1312                 } else {
1313                         $useIndex = '';
1314                 }
1315                 if ( isset( $options['IGNORE INDEX'] ) && is_string( $options['IGNORE INDEX'] ) ) {
1316                         $ignoreIndex = $this->ignoreIndexClause( $options['IGNORE INDEX'] );
1317                 } else {
1318                         $ignoreIndex = '';
1319                 }
1320
1321                 return [ $startOpts, $useIndex, $preLimitTail, $postLimitTail, $ignoreIndex ];
1322         }
1323
1324         /**
1325          * Returns an optional GROUP BY with an optional HAVING
1326          *
1327          * @param array $options Associative array of options
1328          * @return string
1329          * @see DatabaseBase::select()
1330          * @since 1.21
1331          */
1332         public function makeGroupByWithHaving( $options ) {
1333                 $sql = '';
1334                 if ( isset( $options['GROUP BY'] ) ) {
1335                         $gb = is_array( $options['GROUP BY'] )
1336                                 ? implode( ',', $options['GROUP BY'] )
1337                                 : $options['GROUP BY'];
1338                         $sql .= ' GROUP BY ' . $gb;
1339                 }
1340                 if ( isset( $options['HAVING'] ) ) {
1341                         $having = is_array( $options['HAVING'] )
1342                                 ? $this->makeList( $options['HAVING'], LIST_AND )
1343                                 : $options['HAVING'];
1344                         $sql .= ' HAVING ' . $having;
1345                 }
1346
1347                 return $sql;
1348         }
1349
1350         /**
1351          * Returns an optional ORDER BY
1352          *
1353          * @param array $options Associative array of options
1354          * @return string
1355          * @see DatabaseBase::select()
1356          * @since 1.21
1357          */
1358         public function makeOrderBy( $options ) {
1359                 if ( isset( $options['ORDER BY'] ) ) {
1360                         $ob = is_array( $options['ORDER BY'] )
1361                                 ? implode( ',', $options['ORDER BY'] )
1362                                 : $options['ORDER BY'];
1363
1364                         return ' ORDER BY ' . $ob;
1365                 }
1366
1367                 return '';
1368         }
1369
1370         // See IDatabase::select for the docs for this function
1371         public function select( $table, $vars, $conds = '', $fname = __METHOD__,
1372                 $options = [], $join_conds = [] ) {
1373                 $sql = $this->selectSQLText( $table, $vars, $conds, $fname, $options, $join_conds );
1374
1375                 return $this->query( $sql, $fname );
1376         }
1377
1378         public function selectSQLText( $table, $vars, $conds = '', $fname = __METHOD__,
1379                 $options = [], $join_conds = []
1380         ) {
1381                 if ( is_array( $vars ) ) {
1382                         $vars = implode( ',', $this->fieldNamesWithAlias( $vars ) );
1383                 }
1384
1385                 $options = (array)$options;
1386                 $useIndexes = ( isset( $options['USE INDEX'] ) && is_array( $options['USE INDEX'] ) )
1387                         ? $options['USE INDEX']
1388                         : [];
1389                 $ignoreIndexes = ( isset( $options['IGNORE INDEX'] ) && is_array( $options['IGNORE INDEX'] ) )
1390                         ? $options['IGNORE INDEX']
1391                         : [];
1392
1393                 if ( is_array( $table ) ) {
1394                         $from = ' FROM ' .
1395                                 $this->tableNamesWithIndexClauseOrJOIN( $table, $useIndexes, $ignoreIndexes, $join_conds );
1396                 } elseif ( $table != '' ) {
1397                         if ( $table[0] == ' ' ) {
1398                                 $from = ' FROM ' . $table;
1399                         } else {
1400                                 $from = ' FROM ' .
1401                                         $this->tableNamesWithIndexClauseOrJOIN( [ $table ], $useIndexes, $ignoreIndexes, [] );
1402                         }
1403                 } else {
1404                         $from = '';
1405                 }
1406
1407                 list( $startOpts, $useIndex, $preLimitTail, $postLimitTail, $ignoreIndex ) =
1408                         $this->makeSelectOptions( $options );
1409
1410                 if ( !empty( $conds ) ) {
1411                         if ( is_array( $conds ) ) {
1412                                 $conds = $this->makeList( $conds, LIST_AND );
1413                         }
1414                         $sql = "SELECT $startOpts $vars $from $useIndex $ignoreIndex WHERE $conds $preLimitTail";
1415                 } else {
1416                         $sql = "SELECT $startOpts $vars $from $useIndex $ignoreIndex $preLimitTail";
1417                 }
1418
1419                 if ( isset( $options['LIMIT'] ) ) {
1420                         $sql = $this->limitResult( $sql, $options['LIMIT'],
1421                                 isset( $options['OFFSET'] ) ? $options['OFFSET'] : false );
1422                 }
1423                 $sql = "$sql $postLimitTail";
1424
1425                 if ( isset( $options['EXPLAIN'] ) ) {
1426                         $sql = 'EXPLAIN ' . $sql;
1427                 }
1428
1429                 return $sql;
1430         }
1431
1432         public function selectRow( $table, $vars, $conds, $fname = __METHOD__,
1433                 $options = [], $join_conds = []
1434         ) {
1435                 $options = (array)$options;
1436                 $options['LIMIT'] = 1;
1437                 $res = $this->select( $table, $vars, $conds, $fname, $options, $join_conds );
1438
1439                 if ( $res === false ) {
1440                         return false;
1441                 }
1442
1443                 if ( !$this->numRows( $res ) ) {
1444                         return false;
1445                 }
1446
1447                 $obj = $this->fetchObject( $res );
1448
1449                 return $obj;
1450         }
1451
1452         public function estimateRowCount(
1453                 $table, $vars = '*', $conds = '', $fname = __METHOD__, $options = []
1454         ) {
1455                 $rows = 0;
1456                 $res = $this->select( $table, [ 'rowcount' => 'COUNT(*)' ], $conds, $fname, $options );
1457
1458                 if ( $res ) {
1459                         $row = $this->fetchRow( $res );
1460                         $rows = ( isset( $row['rowcount'] ) ) ? (int)$row['rowcount'] : 0;
1461                 }
1462
1463                 return $rows;
1464         }
1465
1466         public function selectRowCount(
1467                 $tables, $vars = '*', $conds = '', $fname = __METHOD__, $options = [], $join_conds = []
1468         ) {
1469                 $rows = 0;
1470                 $sql = $this->selectSQLText( $tables, '1', $conds, $fname, $options, $join_conds );
1471                 $res = $this->query( "SELECT COUNT(*) AS rowcount FROM ($sql) tmp_count", $fname );
1472
1473                 if ( $res ) {
1474                         $row = $this->fetchRow( $res );
1475                         $rows = ( isset( $row['rowcount'] ) ) ? (int)$row['rowcount'] : 0;
1476                 }
1477
1478                 return $rows;
1479         }
1480
1481         /**
1482          * Removes most variables from an SQL query and replaces them with X or N for numbers.
1483          * It's only slightly flawed. Don't use for anything important.
1484          *
1485          * @param string $sql A SQL Query
1486          *
1487          * @return string
1488          */
1489         protected static function generalizeSQL( $sql ) {
1490                 # This does the same as the regexp below would do, but in such a way
1491                 # as to avoid crashing php on some large strings.
1492                 # $sql = preg_replace( "/'([^\\\\']|\\\\.)*'|\"([^\\\\\"]|\\\\.)*\"/", "'X'", $sql );
1493
1494                 $sql = str_replace( "\\\\", '', $sql );
1495                 $sql = str_replace( "\\'", '', $sql );
1496                 $sql = str_replace( "\\\"", '', $sql );
1497                 $sql = preg_replace( "/'.*'/s", "'X'", $sql );
1498                 $sql = preg_replace( '/".*"/s', "'X'", $sql );
1499
1500                 # All newlines, tabs, etc replaced by single space
1501                 $sql = preg_replace( '/\s+/', ' ', $sql );
1502
1503                 # All numbers => N,
1504                 # except the ones surrounded by characters, e.g. l10n
1505                 $sql = preg_replace( '/-?\d+(,-?\d+)+/s', 'N,...,N', $sql );
1506                 $sql = preg_replace( '/(?<![a-zA-Z])-?\d+(?![a-zA-Z])/s', 'N', $sql );
1507
1508                 return $sql;
1509         }
1510
1511         public function fieldExists( $table, $field, $fname = __METHOD__ ) {
1512                 $info = $this->fieldInfo( $table, $field );
1513
1514                 return (bool)$info;
1515         }
1516
1517         public function indexExists( $table, $index, $fname = __METHOD__ ) {
1518                 if ( !$this->tableExists( $table ) ) {
1519                         return null;
1520                 }
1521
1522                 $info = $this->indexInfo( $table, $index, $fname );
1523                 if ( is_null( $info ) ) {
1524                         return null;
1525                 } else {
1526                         return $info !== false;
1527                 }
1528         }
1529
1530         public function tableExists( $table, $fname = __METHOD__ ) {
1531                 $table = $this->tableName( $table );
1532                 $old = $this->ignoreErrors( true );
1533                 $res = $this->query( "SELECT 1 FROM $table LIMIT 1", $fname );
1534                 $this->ignoreErrors( $old );
1535
1536                 return (bool)$res;
1537         }
1538
1539         public function indexUnique( $table, $index ) {
1540                 $indexInfo = $this->indexInfo( $table, $index );
1541
1542                 if ( !$indexInfo ) {
1543                         return null;
1544                 }
1545
1546                 return !$indexInfo[0]->Non_unique;
1547         }
1548
1549         /**
1550          * Helper for DatabaseBase::insert().
1551          *
1552          * @param array $options
1553          * @return string
1554          */
1555         protected function makeInsertOptions( $options ) {
1556                 return implode( ' ', $options );
1557         }
1558
1559         public function insert( $table, $a, $fname = __METHOD__, $options = [] ) {
1560                 # No rows to insert, easy just return now
1561                 if ( !count( $a ) ) {
1562                         return true;
1563                 }
1564
1565                 $table = $this->tableName( $table );
1566
1567                 if ( !is_array( $options ) ) {
1568                         $options = [ $options ];
1569                 }
1570
1571                 $fh = null;
1572                 if ( isset( $options['fileHandle'] ) ) {
1573                         $fh = $options['fileHandle'];
1574                 }
1575                 $options = $this->makeInsertOptions( $options );
1576
1577                 if ( isset( $a[0] ) && is_array( $a[0] ) ) {
1578                         $multi = true;
1579                         $keys = array_keys( $a[0] );
1580                 } else {
1581                         $multi = false;
1582                         $keys = array_keys( $a );
1583                 }
1584
1585                 $sql = 'INSERT ' . $options .
1586                         " INTO $table (" . implode( ',', $keys ) . ') VALUES ';
1587
1588                 if ( $multi ) {
1589                         $first = true;
1590                         foreach ( $a as $row ) {
1591                                 if ( $first ) {
1592                                         $first = false;
1593                                 } else {
1594                                         $sql .= ',';
1595                                 }
1596                                 $sql .= '(' . $this->makeList( $row ) . ')';
1597                         }
1598                 } else {
1599                         $sql .= '(' . $this->makeList( $a ) . ')';
1600                 }
1601
1602                 if ( $fh !== null && false === fwrite( $fh, $sql ) ) {
1603                         return false;
1604                 } elseif ( $fh !== null ) {
1605                         return true;
1606                 }
1607
1608                 return (bool)$this->query( $sql, $fname );
1609         }
1610
1611         /**
1612          * Make UPDATE options array for DatabaseBase::makeUpdateOptions
1613          *
1614          * @param array $options
1615          * @return array
1616          */
1617         protected function makeUpdateOptionsArray( $options ) {
1618                 if ( !is_array( $options ) ) {
1619                         $options = [ $options ];
1620                 }
1621
1622                 $opts = [];
1623
1624                 if ( in_array( 'LOW_PRIORITY', $options ) ) {
1625                         $opts[] = $this->lowPriorityOption();
1626                 }
1627
1628                 if ( in_array( 'IGNORE', $options ) ) {
1629                         $opts[] = 'IGNORE';
1630                 }
1631
1632                 return $opts;
1633         }
1634
1635         /**
1636          * Make UPDATE options for the DatabaseBase::update function
1637          *
1638          * @param array $options The options passed to DatabaseBase::update
1639          * @return string
1640          */
1641         protected function makeUpdateOptions( $options ) {
1642                 $opts = $this->makeUpdateOptionsArray( $options );
1643
1644                 return implode( ' ', $opts );
1645         }
1646
1647         function update( $table, $values, $conds, $fname = __METHOD__, $options = [] ) {
1648                 $table = $this->tableName( $table );
1649                 $opts = $this->makeUpdateOptions( $options );
1650                 $sql = "UPDATE $opts $table SET " . $this->makeList( $values, LIST_SET );
1651
1652                 if ( $conds !== [] && $conds !== '*' ) {
1653                         $sql .= " WHERE " . $this->makeList( $conds, LIST_AND );
1654                 }
1655
1656                 return $this->query( $sql, $fname );
1657         }
1658
1659         public function makeList( $a, $mode = LIST_COMMA ) {
1660                 if ( !is_array( $a ) ) {
1661                         throw new DBUnexpectedError( $this, __METHOD__ . ' called with incorrect parameters' );
1662                 }
1663
1664                 $first = true;
1665                 $list = '';
1666
1667                 foreach ( $a as $field => $value ) {
1668                         if ( !$first ) {
1669                                 if ( $mode == LIST_AND ) {
1670                                         $list .= ' AND ';
1671                                 } elseif ( $mode == LIST_OR ) {
1672                                         $list .= ' OR ';
1673                                 } else {
1674                                         $list .= ',';
1675                                 }
1676                         } else {
1677                                 $first = false;
1678                         }
1679
1680                         if ( ( $mode == LIST_AND || $mode == LIST_OR ) && is_numeric( $field ) ) {
1681                                 $list .= "($value)";
1682                         } elseif ( ( $mode == LIST_SET ) && is_numeric( $field ) ) {
1683                                 $list .= "$value";
1684                         } elseif ( ( $mode == LIST_AND || $mode == LIST_OR ) && is_array( $value ) ) {
1685                                 // Remove null from array to be handled separately if found
1686                                 $includeNull = false;
1687                                 foreach ( array_keys( $value, null, true ) as $nullKey ) {
1688                                         $includeNull = true;
1689                                         unset( $value[$nullKey] );
1690                                 }
1691                                 if ( count( $value ) == 0 && !$includeNull ) {
1692                                         throw new InvalidArgumentException( __METHOD__ . ": empty input for field $field" );
1693                                 } elseif ( count( $value ) == 0 ) {
1694                                         // only check if $field is null
1695                                         $list .= "$field IS NULL";
1696                                 } else {
1697                                         // IN clause contains at least one valid element
1698                                         if ( $includeNull ) {
1699                                                 // Group subconditions to ensure correct precedence
1700                                                 $list .= '(';
1701                                         }
1702                                         if ( count( $value ) == 1 ) {
1703                                                 // Special-case single values, as IN isn't terribly efficient
1704                                                 // Don't necessarily assume the single key is 0; we don't
1705                                                 // enforce linear numeric ordering on other arrays here.
1706                                                 $value = array_values( $value )[0];
1707                                                 $list .= $field . " = " . $this->addQuotes( $value );
1708                                         } else {
1709                                                 $list .= $field . " IN (" . $this->makeList( $value ) . ") ";
1710                                         }
1711                                         // if null present in array, append IS NULL
1712                                         if ( $includeNull ) {
1713                                                 $list .= " OR $field IS NULL)";
1714                                         }
1715                                 }
1716                         } elseif ( $value === null ) {
1717                                 if ( $mode == LIST_AND || $mode == LIST_OR ) {
1718                                         $list .= "$field IS ";
1719                                 } elseif ( $mode == LIST_SET ) {
1720                                         $list .= "$field = ";
1721                                 }
1722                                 $list .= 'NULL';
1723                         } else {
1724                                 if ( $mode == LIST_AND || $mode == LIST_OR || $mode == LIST_SET ) {
1725                                         $list .= "$field = ";
1726                                 }
1727                                 $list .= $mode == LIST_NAMES ? $value : $this->addQuotes( $value );
1728                         }
1729                 }
1730
1731                 return $list;
1732         }
1733
1734         public function makeWhereFrom2d( $data, $baseKey, $subKey ) {
1735                 $conds = [];
1736
1737                 foreach ( $data as $base => $sub ) {
1738                         if ( count( $sub ) ) {
1739                                 $conds[] = $this->makeList(
1740                                         [ $baseKey => $base, $subKey => array_keys( $sub ) ],
1741                                         LIST_AND );
1742                         }
1743                 }
1744
1745                 if ( $conds ) {
1746                         return $this->makeList( $conds, LIST_OR );
1747                 } else {
1748                         // Nothing to search for...
1749                         return false;
1750                 }
1751         }
1752
1753         /**
1754          * Return aggregated value alias
1755          *
1756          * @param array $valuedata
1757          * @param string $valuename
1758          *
1759          * @return string
1760          */
1761         public function aggregateValue( $valuedata, $valuename = 'value' ) {
1762                 return $valuename;
1763         }
1764
1765         public function bitNot( $field ) {
1766                 return "(~$field)";
1767         }
1768
1769         public function bitAnd( $fieldLeft, $fieldRight ) {
1770                 return "($fieldLeft & $fieldRight)";
1771         }
1772
1773         public function bitOr( $fieldLeft, $fieldRight ) {
1774                 return "($fieldLeft | $fieldRight)";
1775         }
1776
1777         public function buildConcat( $stringList ) {
1778                 return 'CONCAT(' . implode( ',', $stringList ) . ')';
1779         }
1780
1781         public function buildGroupConcatField(
1782                 $delim, $table, $field, $conds = '', $join_conds = []
1783         ) {
1784                 $fld = "GROUP_CONCAT($field SEPARATOR " . $this->addQuotes( $delim ) . ')';
1785
1786                 return '(' . $this->selectSQLText( $table, $fld, $conds, null, [], $join_conds ) . ')';
1787         }
1788
1789         /**
1790          * @param string $field Field or column to cast
1791          * @return string
1792          * @since 1.28
1793          */
1794         public function buildStringCast( $field ) {
1795                 return $field;
1796         }
1797
1798         public function selectDB( $db ) {
1799                 # Stub. Shouldn't cause serious problems if it's not overridden, but
1800                 # if your database engine supports a concept similar to MySQL's
1801                 # databases you may as well.
1802                 $this->mDBname = $db;
1803
1804                 return true;
1805         }
1806
1807         public function getDBname() {
1808                 return $this->mDBname;
1809         }
1810
1811         public function getServer() {
1812                 return $this->mServer;
1813         }
1814
1815         /**
1816          * Format a table name ready for use in constructing an SQL query
1817          *
1818          * This does two important things: it quotes the table names to clean them up,
1819          * and it adds a table prefix if only given a table name with no quotes.
1820          *
1821          * All functions of this object which require a table name call this function
1822          * themselves. Pass the canonical name to such functions. This is only needed
1823          * when calling query() directly.
1824          *
1825          * @note This function does not sanitize user input. It is not safe to use
1826          *   this function to escape user input.
1827          * @param string $name Database table name
1828          * @param string $format One of:
1829          *   quoted - Automatically pass the table name through addIdentifierQuotes()
1830          *            so that it can be used in a query.
1831          *   raw - Do not add identifier quotes to the table name
1832          * @return string Full database name
1833          */
1834         public function tableName( $name, $format = 'quoted' ) {
1835                 # Skip the entire process when we have a string quoted on both ends.
1836                 # Note that we check the end so that we will still quote any use of
1837                 # use of `database`.table. But won't break things if someone wants
1838                 # to query a database table with a dot in the name.
1839                 if ( $this->isQuotedIdentifier( $name ) ) {
1840                         return $name;
1841                 }
1842
1843                 # Lets test for any bits of text that should never show up in a table
1844                 # name. Basically anything like JOIN or ON which are actually part of
1845                 # SQL queries, but may end up inside of the table value to combine
1846                 # sql. Such as how the API is doing.
1847                 # Note that we use a whitespace test rather than a \b test to avoid
1848                 # any remote case where a word like on may be inside of a table name
1849                 # surrounded by symbols which may be considered word breaks.
1850                 if ( preg_match( '/(^|\s)(DISTINCT|JOIN|ON|AS)(\s|$)/i', $name ) !== 0 ) {
1851                         return $name;
1852                 }
1853
1854                 # Split database and table into proper variables.
1855                 # We reverse the explode so that database.table and table both output
1856                 # the correct table.
1857                 $dbDetails = explode( '.', $name, 3 );
1858                 if ( count( $dbDetails ) == 3 ) {
1859                         list( $database, $schema, $table ) = $dbDetails;
1860                         # We don't want any prefix added in this case
1861                         $prefix = '';
1862                 } elseif ( count( $dbDetails ) == 2 ) {
1863                         list( $database, $table ) = $dbDetails;
1864                         # We don't want any prefix added in this case
1865                         # In dbs that support it, $database may actually be the schema
1866                         # but that doesn't affect any of the functionality here
1867                         $prefix = '';
1868                         $schema = null;
1869                 } else {
1870                         list( $table ) = $dbDetails;
1871                         if ( isset( $this->tableAliases[$table] ) ) {
1872                                 $database = $this->tableAliases[$table]['dbname'];
1873                                 $schema = is_string( $this->tableAliases[$table]['schema'] )
1874                                         ? $this->tableAliases[$table]['schema']
1875                                         : $this->mSchema;
1876                                 $prefix = is_string( $this->tableAliases[$table]['prefix'] )
1877                                         ? $this->tableAliases[$table]['prefix']
1878                                         : $this->mTablePrefix;
1879                         } else {
1880                                 $database = null;
1881                                 $schema = $this->mSchema; # Default schema
1882                                 $prefix = $this->mTablePrefix; # Default prefix
1883                         }
1884                 }
1885
1886                 # Quote $table and apply the prefix if not quoted.
1887                 # $tableName might be empty if this is called from Database::replaceVars()
1888                 $tableName = "{$prefix}{$table}";
1889                 if ( $format == 'quoted'
1890                         && !$this->isQuotedIdentifier( $tableName ) && $tableName !== ''
1891                 ) {
1892                         $tableName = $this->addIdentifierQuotes( $tableName );
1893                 }
1894
1895                 # Quote $schema and merge it with the table name if needed
1896                 if ( strlen( $schema ) ) {
1897                         if ( $format == 'quoted' && !$this->isQuotedIdentifier( $schema ) ) {
1898                                 $schema = $this->addIdentifierQuotes( $schema );
1899                         }
1900                         $tableName = $schema . '.' . $tableName;
1901                 }
1902
1903                 # Quote $database and merge it with the table name if needed
1904                 if ( $database !== null ) {
1905                         if ( $format == 'quoted' && !$this->isQuotedIdentifier( $database ) ) {
1906                                 $database = $this->addIdentifierQuotes( $database );
1907                         }
1908                         $tableName = $database . '.' . $tableName;
1909                 }
1910
1911                 return $tableName;
1912         }
1913
1914         /**
1915          * Fetch a number of table names into an array
1916          * This is handy when you need to construct SQL for joins
1917          *
1918          * Example:
1919          * extract( $dbr->tableNames( 'user', 'watchlist' ) );
1920          * $sql = "SELECT wl_namespace,wl_title FROM $watchlist,$user
1921          *         WHERE wl_user=user_id AND wl_user=$nameWithQuotes";
1922          *
1923          * @return array
1924          */
1925         public function tableNames() {
1926                 $inArray = func_get_args();
1927                 $retVal = [];
1928
1929                 foreach ( $inArray as $name ) {
1930                         $retVal[$name] = $this->tableName( $name );
1931                 }
1932
1933                 return $retVal;
1934         }
1935
1936         /**
1937          * Fetch a number of table names into an zero-indexed numerical array
1938          * This is handy when you need to construct SQL for joins
1939          *
1940          * Example:
1941          * list( $user, $watchlist ) = $dbr->tableNamesN( 'user', 'watchlist' );
1942          * $sql = "SELECT wl_namespace,wl_title FROM $watchlist,$user
1943          *         WHERE wl_user=user_id AND wl_user=$nameWithQuotes";
1944          *
1945          * @return array
1946          */
1947         public function tableNamesN() {
1948                 $inArray = func_get_args();
1949                 $retVal = [];
1950
1951                 foreach ( $inArray as $name ) {
1952                         $retVal[] = $this->tableName( $name );
1953                 }
1954
1955                 return $retVal;
1956         }
1957
1958         /**
1959          * Get an aliased table name
1960          * e.g. tableName AS newTableName
1961          *
1962          * @param string $name Table name, see tableName()
1963          * @param string|bool $alias Alias (optional)
1964          * @return string SQL name for aliased table. Will not alias a table to its own name
1965          */
1966         public function tableNameWithAlias( $name, $alias = false ) {
1967                 if ( !$alias || $alias == $name ) {
1968                         return $this->tableName( $name );
1969                 } else {
1970                         return $this->tableName( $name ) . ' ' . $this->addIdentifierQuotes( $alias );
1971                 }
1972         }
1973
1974         /**
1975          * Gets an array of aliased table names
1976          *
1977          * @param array $tables [ [alias] => table ]
1978          * @return string[] See tableNameWithAlias()
1979          */
1980         public function tableNamesWithAlias( $tables ) {
1981                 $retval = [];
1982                 foreach ( $tables as $alias => $table ) {
1983                         if ( is_numeric( $alias ) ) {
1984                                 $alias = $table;
1985                         }
1986                         $retval[] = $this->tableNameWithAlias( $table, $alias );
1987                 }
1988
1989                 return $retval;
1990         }
1991
1992         /**
1993          * Get an aliased field name
1994          * e.g. fieldName AS newFieldName
1995          *
1996          * @param string $name Field name
1997          * @param string|bool $alias Alias (optional)
1998          * @return string SQL name for aliased field. Will not alias a field to its own name
1999          */
2000         public function fieldNameWithAlias( $name, $alias = false ) {
2001                 if ( !$alias || (string)$alias === (string)$name ) {
2002                         return $name;
2003                 } else {
2004                         return $name . ' AS ' . $this->addIdentifierQuotes( $alias ); // PostgreSQL needs AS
2005                 }
2006         }
2007
2008         /**
2009          * Gets an array of aliased field names
2010          *
2011          * @param array $fields [ [alias] => field ]
2012          * @return string[] See fieldNameWithAlias()
2013          */
2014         public function fieldNamesWithAlias( $fields ) {
2015                 $retval = [];
2016                 foreach ( $fields as $alias => $field ) {
2017                         if ( is_numeric( $alias ) ) {
2018                                 $alias = $field;
2019                         }
2020                         $retval[] = $this->fieldNameWithAlias( $field, $alias );
2021                 }
2022
2023                 return $retval;
2024         }
2025
2026         /**
2027          * Get the aliased table name clause for a FROM clause
2028          * which might have a JOIN and/or USE INDEX or IGNORE INDEX clause
2029          *
2030          * @param array $tables ( [alias] => table )
2031          * @param array $use_index Same as for select()
2032          * @param array $ignore_index Same as for select()
2033          * @param array $join_conds Same as for select()
2034          * @return string
2035          */
2036         protected function tableNamesWithIndexClauseOrJOIN(
2037                 $tables, $use_index = [], $ignore_index = [], $join_conds = []
2038         ) {
2039                 $ret = [];
2040                 $retJOIN = [];
2041                 $use_index = (array)$use_index;
2042                 $ignore_index = (array)$ignore_index;
2043                 $join_conds = (array)$join_conds;
2044
2045                 foreach ( $tables as $alias => $table ) {
2046                         if ( !is_string( $alias ) ) {
2047                                 // No alias? Set it equal to the table name
2048                                 $alias = $table;
2049                         }
2050                         // Is there a JOIN clause for this table?
2051                         if ( isset( $join_conds[$alias] ) ) {
2052                                 list( $joinType, $conds ) = $join_conds[$alias];
2053                                 $tableClause = $joinType;
2054                                 $tableClause .= ' ' . $this->tableNameWithAlias( $table, $alias );
2055                                 if ( isset( $use_index[$alias] ) ) { // has USE INDEX?
2056                                         $use = $this->useIndexClause( implode( ',', (array)$use_index[$alias] ) );
2057                                         if ( $use != '' ) {
2058                                                 $tableClause .= ' ' . $use;
2059                                         }
2060                                 }
2061                                 if ( isset( $ignore_index[$alias] ) ) { // has IGNORE INDEX?
2062                                         $ignore = $this->ignoreIndexClause( implode( ',', (array)$ignore_index[$alias] ) );
2063                                         if ( $ignore != '' ) {
2064                                                 $tableClause .= ' ' . $ignore;
2065                                         }
2066                                 }
2067                                 $on = $this->makeList( (array)$conds, LIST_AND );
2068                                 if ( $on != '' ) {
2069                                         $tableClause .= ' ON (' . $on . ')';
2070                                 }
2071
2072                                 $retJOIN[] = $tableClause;
2073                         } elseif ( isset( $use_index[$alias] ) ) {
2074                                 // Is there an INDEX clause for this table?
2075                                 $tableClause = $this->tableNameWithAlias( $table, $alias );
2076                                 $tableClause .= ' ' . $this->useIndexClause(
2077                                         implode( ',', (array)$use_index[$alias] )
2078                                 );
2079
2080                                 $ret[] = $tableClause;
2081                         } elseif ( isset( $ignore_index[$alias] ) ) {
2082                                 // Is there an INDEX clause for this table?
2083                                 $tableClause = $this->tableNameWithAlias( $table, $alias );
2084                                 $tableClause .= ' ' . $this->ignoreIndexClause(
2085                                         implode( ',', (array)$ignore_index[$alias] )
2086                                 );
2087
2088                                 $ret[] = $tableClause;
2089                         } else {
2090                                 $tableClause = $this->tableNameWithAlias( $table, $alias );
2091
2092                                 $ret[] = $tableClause;
2093                         }
2094                 }
2095
2096                 // We can't separate explicit JOIN clauses with ',', use ' ' for those
2097                 $implicitJoins = !empty( $ret ) ? implode( ',', $ret ) : "";
2098                 $explicitJoins = !empty( $retJOIN ) ? implode( ' ', $retJOIN ) : "";
2099
2100                 // Compile our final table clause
2101                 return implode( ' ', [ $implicitJoins, $explicitJoins ] );
2102         }
2103
2104         /**
2105          * Get the name of an index in a given table.
2106          *
2107          * @param string $index
2108          * @return string
2109          */
2110         protected function indexName( $index ) {
2111                 // Backwards-compatibility hack
2112                 $renamed = [
2113                         'ar_usertext_timestamp' => 'usertext_timestamp',
2114                         'un_user_id' => 'user_id',
2115                         'un_user_ip' => 'user_ip',
2116                 ];
2117
2118                 if ( isset( $renamed[$index] ) ) {
2119                         return $renamed[$index];
2120                 } else {
2121                         return $index;
2122                 }
2123         }
2124
2125         public function addQuotes( $s ) {
2126                 if ( $s instanceof Blob ) {
2127                         $s = $s->fetch();
2128                 }
2129                 if ( $s === null ) {
2130                         return 'NULL';
2131                 } else {
2132                         # This will also quote numeric values. This should be harmless,
2133                         # and protects against weird problems that occur when they really
2134                         # _are_ strings such as article titles and string->number->string
2135                         # conversion is not 1:1.
2136                         return "'" . $this->strencode( $s ) . "'";
2137                 }
2138         }
2139
2140         /**
2141          * Quotes an identifier using `backticks` or "double quotes" depending on the database type.
2142          * MySQL uses `backticks` while basically everything else uses double quotes.
2143          * Since MySQL is the odd one out here the double quotes are our generic
2144          * and we implement backticks in DatabaseMysql.
2145          *
2146          * @param string $s
2147          * @return string
2148          */
2149         public function addIdentifierQuotes( $s ) {
2150                 return '"' . str_replace( '"', '""', $s ) . '"';
2151         }
2152
2153         /**
2154          * Returns if the given identifier looks quoted or not according to
2155          * the database convention for quoting identifiers .
2156          *
2157          * @note Do not use this to determine if untrusted input is safe.
2158          *   A malicious user can trick this function.
2159          * @param string $name
2160          * @return bool
2161          */
2162         public function isQuotedIdentifier( $name ) {
2163                 return $name[0] == '"' && substr( $name, -1, 1 ) == '"';
2164         }
2165
2166         /**
2167          * @param string $s
2168          * @return string
2169          */
2170         protected function escapeLikeInternal( $s ) {
2171                 return addcslashes( $s, '\%_' );
2172         }
2173
2174         public function buildLike() {
2175                 $params = func_get_args();
2176
2177                 if ( count( $params ) > 0 && is_array( $params[0] ) ) {
2178                         $params = $params[0];
2179                 }
2180
2181                 $s = '';
2182
2183                 foreach ( $params as $value ) {
2184                         if ( $value instanceof LikeMatch ) {
2185                                 $s .= $value->toString();
2186                         } else {
2187                                 $s .= $this->escapeLikeInternal( $value );
2188                         }
2189                 }
2190
2191                 return " LIKE {$this->addQuotes( $s )} ";
2192         }
2193
2194         public function anyChar() {
2195                 return new LikeMatch( '_' );
2196         }
2197
2198         public function anyString() {
2199                 return new LikeMatch( '%' );
2200         }
2201
2202         public function nextSequenceValue( $seqName ) {
2203                 return null;
2204         }
2205
2206         /**
2207          * USE INDEX clause. Unlikely to be useful for anything but MySQL. This
2208          * is only needed because a) MySQL must be as efficient as possible due to
2209          * its use on Wikipedia, and b) MySQL 4.0 is kind of dumb sometimes about
2210          * which index to pick. Anyway, other databases might have different
2211          * indexes on a given table. So don't bother overriding this unless you're
2212          * MySQL.
2213          * @param string $index
2214          * @return string
2215          */
2216         public function useIndexClause( $index ) {
2217                 return '';
2218         }
2219
2220         /**
2221          * IGNORE INDEX clause. Unlikely to be useful for anything but MySQL. This
2222          * is only needed because a) MySQL must be as efficient as possible due to
2223          * its use on Wikipedia, and b) MySQL 4.0 is kind of dumb sometimes about
2224          * which index to pick. Anyway, other databases might have different
2225          * indexes on a given table. So don't bother overriding this unless you're
2226          * MySQL.
2227          * @param string $index
2228          * @return string
2229          */
2230         public function ignoreIndexClause( $index ) {
2231                 return '';
2232         }
2233
2234         public function replace( $table, $uniqueIndexes, $rows, $fname = __METHOD__ ) {
2235                 $quotedTable = $this->tableName( $table );
2236
2237                 if ( count( $rows ) == 0 ) {
2238                         return;
2239                 }
2240
2241                 # Single row case
2242                 if ( !is_array( reset( $rows ) ) ) {
2243                         $rows = [ $rows ];
2244                 }
2245
2246                 // @FXIME: this is not atomic, but a trx would break affectedRows()
2247                 foreach ( $rows as $row ) {
2248                         # Delete rows which collide
2249                         if ( $uniqueIndexes ) {
2250                                 $sql = "DELETE FROM $quotedTable WHERE ";
2251                                 $first = true;
2252                                 foreach ( $uniqueIndexes as $index ) {
2253                                         if ( $first ) {
2254                                                 $first = false;
2255                                                 $sql .= '( ';
2256                                         } else {
2257                                                 $sql .= ' ) OR ( ';
2258                                         }
2259                                         if ( is_array( $index ) ) {
2260                                                 $first2 = true;
2261                                                 foreach ( $index as $col ) {
2262                                                         if ( $first2 ) {
2263                                                                 $first2 = false;
2264                                                         } else {
2265                                                                 $sql .= ' AND ';
2266                                                         }
2267                                                         $sql .= $col . '=' . $this->addQuotes( $row[$col] );
2268                                                 }
2269                                         } else {
2270                                                 $sql .= $index . '=' . $this->addQuotes( $row[$index] );
2271                                         }
2272                                 }
2273                                 $sql .= ' )';
2274                                 $this->query( $sql, $fname );
2275                         }
2276
2277                         # Now insert the row
2278                         $this->insert( $table, $row, $fname );
2279                 }
2280         }
2281
2282         /**
2283          * REPLACE query wrapper for MySQL and SQLite, which have a native REPLACE
2284          * statement.
2285          *
2286          * @param string $table Table name
2287          * @param array|string $rows Row(s) to insert
2288          * @param string $fname Caller function name
2289          *
2290          * @return ResultWrapper
2291          */
2292         protected function nativeReplace( $table, $rows, $fname ) {
2293                 $table = $this->tableName( $table );
2294
2295                 # Single row case
2296                 if ( !is_array( reset( $rows ) ) ) {
2297                         $rows = [ $rows ];
2298                 }
2299
2300                 $sql = "REPLACE INTO $table (" . implode( ',', array_keys( $rows[0] ) ) . ') VALUES ';
2301                 $first = true;
2302
2303                 foreach ( $rows as $row ) {
2304                         if ( $first ) {
2305                                 $first = false;
2306                         } else {
2307                                 $sql .= ',';
2308                         }
2309
2310                         $sql .= '(' . $this->makeList( $row ) . ')';
2311                 }
2312
2313                 return $this->query( $sql, $fname );
2314         }
2315
2316         public function upsert( $table, array $rows, array $uniqueIndexes, array $set,
2317                 $fname = __METHOD__
2318         ) {
2319                 if ( !count( $rows ) ) {
2320                         return true; // nothing to do
2321                 }
2322
2323                 if ( !is_array( reset( $rows ) ) ) {
2324                         $rows = [ $rows ];
2325                 }
2326
2327                 if ( count( $uniqueIndexes ) ) {
2328                         $clauses = []; // list WHERE clauses that each identify a single row
2329                         foreach ( $rows as $row ) {
2330                                 foreach ( $uniqueIndexes as $index ) {
2331                                         $index = is_array( $index ) ? $index : [ $index ]; // columns
2332                                         $rowKey = []; // unique key to this row
2333                                         foreach ( $index as $column ) {
2334                                                 $rowKey[$column] = $row[$column];
2335                                         }
2336                                         $clauses[] = $this->makeList( $rowKey, LIST_AND );
2337                                 }
2338                         }
2339                         $where = [ $this->makeList( $clauses, LIST_OR ) ];
2340                 } else {
2341                         $where = false;
2342                 }
2343
2344                 $useTrx = !$this->mTrxLevel;
2345                 if ( $useTrx ) {
2346                         $this->begin( $fname, self::TRANSACTION_INTERNAL );
2347                 }
2348                 try {
2349                         # Update any existing conflicting row(s)
2350                         if ( $where !== false ) {
2351                                 $ok = $this->update( $table, $set, $where, $fname );
2352                         } else {
2353                                 $ok = true;
2354                         }
2355                         # Now insert any non-conflicting row(s)
2356                         $ok = $this->insert( $table, $rows, $fname, [ 'IGNORE' ] ) && $ok;
2357                 } catch ( Exception $e ) {
2358                         if ( $useTrx ) {
2359                                 $this->rollback( $fname, self::FLUSHING_INTERNAL );
2360                         }
2361                         throw $e;
2362                 }
2363                 if ( $useTrx ) {
2364                         $this->commit( $fname, self::FLUSHING_INTERNAL );
2365                 }
2366
2367                 return $ok;
2368         }
2369
2370         public function deleteJoin( $delTable, $joinTable, $delVar, $joinVar, $conds,
2371                 $fname = __METHOD__
2372         ) {
2373                 if ( !$conds ) {
2374                         throw new DBUnexpectedError( $this, __METHOD__ . ' called with empty $conds' );
2375                 }
2376
2377                 $delTable = $this->tableName( $delTable );
2378                 $joinTable = $this->tableName( $joinTable );
2379                 $sql = "DELETE FROM $delTable WHERE $delVar IN (SELECT $joinVar FROM $joinTable ";
2380                 if ( $conds != '*' ) {
2381                         $sql .= 'WHERE ' . $this->makeList( $conds, LIST_AND );
2382                 }
2383                 $sql .= ')';
2384
2385                 $this->query( $sql, $fname );
2386         }
2387
2388         /**
2389          * Returns the size of a text field, or -1 for "unlimited"
2390          *
2391          * @param string $table
2392          * @param string $field
2393          * @return int
2394          */
2395         public function textFieldSize( $table, $field ) {
2396                 $table = $this->tableName( $table );
2397                 $sql = "SHOW COLUMNS FROM $table LIKE \"$field\";";
2398                 $res = $this->query( $sql, __METHOD__ );
2399                 $row = $this->fetchObject( $res );
2400
2401                 $m = [];
2402
2403                 if ( preg_match( '/\((.*)\)/', $row->Type, $m ) ) {
2404                         $size = $m[1];
2405                 } else {
2406                         $size = -1;
2407                 }
2408
2409                 return $size;
2410         }
2411
2412         /**
2413          * A string to insert into queries to show that they're low-priority, like
2414          * MySQL's LOW_PRIORITY. If no such feature exists, return an empty
2415          * string and nothing bad should happen.
2416          *
2417          * @return string Returns the text of the low priority option if it is
2418          *   supported, or a blank string otherwise
2419          */
2420         public function lowPriorityOption() {
2421                 return '';
2422         }
2423
2424         public function delete( $table, $conds, $fname = __METHOD__ ) {
2425                 if ( !$conds ) {
2426                         throw new DBUnexpectedError( $this, __METHOD__ . ' called with no conditions' );
2427                 }
2428
2429                 $table = $this->tableName( $table );
2430                 $sql = "DELETE FROM $table";
2431
2432                 if ( $conds != '*' ) {
2433                         if ( is_array( $conds ) ) {
2434                                 $conds = $this->makeList( $conds, LIST_AND );
2435                         }
2436                         $sql .= ' WHERE ' . $conds;
2437                 }
2438
2439                 return $this->query( $sql, $fname );
2440         }
2441
2442         public function insertSelect(
2443                 $destTable, $srcTable, $varMap, $conds,
2444                 $fname = __METHOD__, $insertOptions = [], $selectOptions = []
2445         ) {
2446                 if ( $this->cliMode ) {
2447                         // For massive migrations with downtime, we don't want to select everything
2448                         // into memory and OOM, so do all this native on the server side if possible.
2449                         return $this->nativeInsertSelect(
2450                                 $destTable,
2451                                 $srcTable,
2452                                 $varMap,
2453                                 $conds,
2454                                 $fname,
2455                                 $insertOptions,
2456                                 $selectOptions
2457                         );
2458                 }
2459
2460                 // For web requests, do a locking SELECT and then INSERT. This puts the SELECT burden
2461                 // on only the master (without needing row-based-replication). It also makes it easy to
2462                 // know how big the INSERT is going to be.
2463                 $fields = [];
2464                 foreach ( $varMap as $dstColumn => $sourceColumnOrSql ) {
2465                         $fields[] = $this->fieldNameWithAlias( $sourceColumnOrSql, $dstColumn );
2466                 }
2467                 $selectOptions[] = 'FOR UPDATE';
2468                 $res = $this->select( $srcTable, implode( ',', $fields ), $conds, $fname, $selectOptions );
2469                 if ( !$res ) {
2470                         return false;
2471                 }
2472
2473                 $rows = [];
2474                 foreach ( $res as $row ) {
2475                         $rows[] = (array)$row;
2476                 }
2477
2478                 return $this->insert( $destTable, $rows, $fname, $insertOptions );
2479         }
2480
2481         public function nativeInsertSelect( $destTable, $srcTable, $varMap, $conds,
2482                 $fname = __METHOD__,
2483                 $insertOptions = [], $selectOptions = []
2484         ) {
2485                 $destTable = $this->tableName( $destTable );
2486
2487                 if ( !is_array( $insertOptions ) ) {
2488                         $insertOptions = [ $insertOptions ];
2489                 }
2490
2491                 $insertOptions = $this->makeInsertOptions( $insertOptions );
2492
2493                 if ( !is_array( $selectOptions ) ) {
2494                         $selectOptions = [ $selectOptions ];
2495                 }
2496
2497                 list( $startOpts, $useIndex, $tailOpts, $ignoreIndex ) = $this->makeSelectOptions(
2498                         $selectOptions );
2499
2500                 if ( is_array( $srcTable ) ) {
2501                         $srcTable = implode( ',', array_map( [ &$this, 'tableName' ], $srcTable ) );
2502                 } else {
2503                         $srcTable = $this->tableName( $srcTable );
2504                 }
2505
2506                 $sql = "INSERT $insertOptions INTO $destTable (" . implode( ',', array_keys( $varMap ) ) . ')' .
2507                         " SELECT $startOpts " . implode( ',', $varMap ) .
2508                         " FROM $srcTable $useIndex $ignoreIndex ";
2509
2510                 if ( $conds != '*' ) {
2511                         if ( is_array( $conds ) ) {
2512                                 $conds = $this->makeList( $conds, LIST_AND );
2513                         }
2514                         $sql .= " WHERE $conds";
2515                 }
2516
2517                 $sql .= " $tailOpts";
2518
2519                 return $this->query( $sql, $fname );
2520         }
2521
2522         /**
2523          * Construct a LIMIT query with optional offset. This is used for query
2524          * pages. The SQL should be adjusted so that only the first $limit rows
2525          * are returned. If $offset is provided as well, then the first $offset
2526          * rows should be discarded, and the next $limit rows should be returned.
2527          * If the result of the query is not ordered, then the rows to be returned
2528          * are theoretically arbitrary.
2529          *
2530          * $sql is expected to be a SELECT, if that makes a difference.
2531          *
2532          * The version provided by default works in MySQL and SQLite. It will very
2533          * likely need to be overridden for most other DBMSes.
2534          *
2535          * @param string $sql SQL query we will append the limit too
2536          * @param int $limit The SQL limit
2537          * @param int|bool $offset The SQL offset (default false)
2538          * @throws DBUnexpectedError
2539          * @return string
2540          */
2541         public function limitResult( $sql, $limit, $offset = false ) {
2542                 if ( !is_numeric( $limit ) ) {
2543                         throw new DBUnexpectedError( $this, "Invalid non-numeric limit passed to limitResult()\n" );
2544                 }
2545
2546                 return "$sql LIMIT "
2547                         . ( ( is_numeric( $offset ) && $offset != 0 ) ? "{$offset}," : "" )
2548                         . "{$limit} ";
2549         }
2550
2551         public function unionSupportsOrderAndLimit() {
2552                 return true; // True for almost every DB supported
2553         }
2554
2555         public function unionQueries( $sqls, $all ) {
2556                 $glue = $all ? ') UNION ALL (' : ') UNION (';
2557
2558                 return '(' . implode( $glue, $sqls ) . ')';
2559         }
2560
2561         public function conditional( $cond, $trueVal, $falseVal ) {
2562                 if ( is_array( $cond ) ) {
2563                         $cond = $this->makeList( $cond, LIST_AND );
2564                 }
2565
2566                 return " (CASE WHEN $cond THEN $trueVal ELSE $falseVal END) ";
2567         }
2568
2569         public function strreplace( $orig, $old, $new ) {
2570                 return "REPLACE({$orig}, {$old}, {$new})";
2571         }
2572
2573         public function getServerUptime() {
2574                 return 0;
2575         }
2576
2577         public function wasDeadlock() {
2578                 return false;
2579         }
2580
2581         public function wasLockTimeout() {
2582                 return false;
2583         }
2584
2585         public function wasErrorReissuable() {
2586                 return false;
2587         }
2588
2589         public function wasReadOnlyError() {
2590                 return false;
2591         }
2592
2593         /**
2594          * Determines if the given query error was a connection drop
2595          * STUB
2596          *
2597          * @param integer|string $errno
2598          * @return bool
2599          */
2600         public function wasConnectionError( $errno ) {
2601                 return false;
2602         }
2603
2604         /**
2605          * Perform a deadlock-prone transaction.
2606          *
2607          * This function invokes a callback function to perform a set of write
2608          * queries. If a deadlock occurs during the processing, the transaction
2609          * will be rolled back and the callback function will be called again.
2610          *
2611          * Avoid using this method outside of Job or Maintenance classes.
2612          *
2613          * Usage:
2614          *   $dbw->deadlockLoop( callback, ... );
2615          *
2616          * Extra arguments are passed through to the specified callback function.
2617          * This method requires that no transactions are already active to avoid
2618          * causing premature commits or exceptions.
2619          *
2620          * Returns whatever the callback function returned on its successful,
2621          * iteration, or false on error, for example if the retry limit was
2622          * reached.
2623          *
2624          * @return mixed
2625          * @throws DBUnexpectedError
2626          * @throws Exception
2627          */
2628         public function deadlockLoop() {
2629                 $args = func_get_args();
2630                 $function = array_shift( $args );
2631                 $tries = self::DEADLOCK_TRIES;
2632
2633                 $this->begin( __METHOD__ );
2634
2635                 $retVal = null;
2636                 /** @var Exception $e */
2637                 $e = null;
2638                 do {
2639                         try {
2640                                 $retVal = call_user_func_array( $function, $args );
2641                                 break;
2642                         } catch ( DBQueryError $e ) {
2643                                 if ( $this->wasDeadlock() ) {
2644                                         // Retry after a randomized delay
2645                                         usleep( mt_rand( self::DEADLOCK_DELAY_MIN, self::DEADLOCK_DELAY_MAX ) );
2646                                 } else {
2647                                         // Throw the error back up
2648                                         throw $e;
2649                                 }
2650                         }
2651                 } while ( --$tries > 0 );
2652
2653                 if ( $tries <= 0 ) {
2654                         // Too many deadlocks; give up
2655                         $this->rollback( __METHOD__ );
2656                         throw $e;
2657                 } else {
2658                         $this->commit( __METHOD__ );
2659
2660                         return $retVal;
2661                 }
2662         }
2663
2664         public function masterPosWait( DBMasterPos $pos, $timeout ) {
2665                 # Real waits are implemented in the subclass.
2666                 return 0;
2667         }
2668
2669         public function getSlavePos() {
2670                 # Stub
2671                 return false;
2672         }
2673
2674         public function getMasterPos() {
2675                 # Stub
2676                 return false;
2677         }
2678
2679         public function serverIsReadOnly() {
2680                 return false;
2681         }
2682
2683         final public function onTransactionResolution( callable $callback, $fname = __METHOD__ ) {
2684                 if ( !$this->mTrxLevel ) {
2685                         throw new DBUnexpectedError( $this, "No transaction is active." );
2686                 }
2687                 $this->mTrxEndCallbacks[] = [ $callback, $fname ];
2688         }
2689
2690         final public function onTransactionIdle( callable $callback, $fname = __METHOD__ ) {
2691                 $this->mTrxIdleCallbacks[] = [ $callback, $fname ];
2692                 if ( !$this->mTrxLevel ) {
2693                         $this->runOnTransactionIdleCallbacks( self::TRIGGER_IDLE );
2694                 }
2695         }
2696
2697         final public function onTransactionPreCommitOrIdle( callable $callback, $fname = __METHOD__ ) {
2698                 if ( $this->mTrxLevel ) {
2699                         $this->mTrxPreCommitCallbacks[] = [ $callback, $fname ];
2700                 } else {
2701                         // If no transaction is active, then make one for this callback
2702                         $this->startAtomic( __METHOD__ );
2703                         try {
2704                                 call_user_func( $callback );
2705                                 $this->endAtomic( __METHOD__ );
2706                         } catch ( Exception $e ) {
2707                                 $this->rollback( __METHOD__, self::FLUSHING_INTERNAL );
2708                                 throw $e;
2709                         }
2710                 }
2711         }
2712
2713         final public function setTransactionListener( $name, callable $callback = null ) {
2714                 if ( $callback ) {
2715                         $this->mTrxRecurringCallbacks[$name] = $callback;
2716                 } else {
2717                         unset( $this->mTrxRecurringCallbacks[$name] );
2718                 }
2719         }
2720
2721         /**
2722          * Whether to disable running of post-COMMIT/ROLLBACK callbacks
2723          *
2724          * This method should not be used outside of Database/LoadBalancer
2725          *
2726          * @param bool $suppress
2727          * @since 1.28
2728          */
2729         final public function setTrxEndCallbackSuppression( $suppress ) {
2730                 $this->mTrxEndCallbacksSuppressed = $suppress;
2731         }
2732
2733         /**
2734          * Actually run and consume any "on transaction idle/resolution" callbacks.
2735          *
2736          * This method should not be used outside of Database/LoadBalancer
2737          *
2738          * @param integer $trigger IDatabase::TRIGGER_* constant
2739          * @since 1.20
2740          * @throws Exception
2741          */
2742         public function runOnTransactionIdleCallbacks( $trigger ) {
2743                 if ( $this->mTrxEndCallbacksSuppressed ) {
2744                         return;
2745                 }
2746
2747                 $autoTrx = $this->getFlag( DBO_TRX ); // automatic begin() enabled?
2748                 /** @var Exception $e */
2749                 $e = null; // first exception
2750                 do { // callbacks may add callbacks :)
2751                         $callbacks = array_merge(
2752                                 $this->mTrxIdleCallbacks,
2753                                 $this->mTrxEndCallbacks // include "transaction resolution" callbacks
2754                         );
2755                         $this->mTrxIdleCallbacks = []; // consumed (and recursion guard)
2756                         $this->mTrxEndCallbacks = []; // consumed (recursion guard)
2757                         foreach ( $callbacks as $callback ) {
2758                                 try {
2759                                         list( $phpCallback ) = $callback;
2760                                         $this->clearFlag( DBO_TRX ); // make each query its own transaction
2761                                         call_user_func_array( $phpCallback, [ $trigger ] );
2762                                         if ( $autoTrx ) {
2763                                                 $this->setFlag( DBO_TRX ); // restore automatic begin()
2764                                         } else {
2765                                                 $this->clearFlag( DBO_TRX ); // restore auto-commit
2766                                         }
2767                                 } catch ( Exception $ex ) {
2768                                         call_user_func( $this->errorLogger, $ex );
2769                                         $e = $e ?: $ex;
2770                                         // Some callbacks may use startAtomic/endAtomic, so make sure
2771                                         // their transactions are ended so other callbacks don't fail
2772                                         if ( $this->trxLevel() ) {
2773                                                 $this->rollback( __METHOD__, self::FLUSHING_INTERNAL );
2774                                         }
2775                                 }
2776                         }
2777                 } while ( count( $this->mTrxIdleCallbacks ) );
2778
2779                 if ( $e instanceof Exception ) {
2780                         throw $e; // re-throw any first exception
2781                 }
2782         }
2783
2784         /**
2785          * Actually run and consume any "on transaction pre-commit" callbacks.
2786          *
2787          * This method should not be used outside of Database/LoadBalancer
2788          *
2789          * @since 1.22
2790          * @throws Exception
2791          */
2792         public function runOnTransactionPreCommitCallbacks() {
2793                 $e = null; // first exception
2794                 do { // callbacks may add callbacks :)
2795                         $callbacks = $this->mTrxPreCommitCallbacks;
2796                         $this->mTrxPreCommitCallbacks = []; // consumed (and recursion guard)
2797                         foreach ( $callbacks as $callback ) {
2798                                 try {
2799                                         list( $phpCallback ) = $callback;
2800                                         call_user_func( $phpCallback );
2801                                 } catch ( Exception $ex ) {
2802                                         call_user_func( $this->errorLogger, $ex );
2803                                         $e = $e ?: $ex;
2804                                 }
2805                         }
2806                 } while ( count( $this->mTrxPreCommitCallbacks ) );
2807
2808                 if ( $e instanceof Exception ) {
2809                         throw $e; // re-throw any first exception
2810                 }
2811         }
2812
2813         /**
2814          * Actually run any "transaction listener" callbacks.
2815          *
2816          * This method should not be used outside of Database/LoadBalancer
2817          *
2818          * @param integer $trigger IDatabase::TRIGGER_* constant
2819          * @throws Exception
2820          * @since 1.20
2821          */
2822         public function runTransactionListenerCallbacks( $trigger ) {
2823                 if ( $this->mTrxEndCallbacksSuppressed ) {
2824                         return;
2825                 }
2826
2827                 /** @var Exception $e */
2828                 $e = null; // first exception
2829
2830                 foreach ( $this->mTrxRecurringCallbacks as $phpCallback ) {
2831                         try {
2832                                 $phpCallback( $trigger, $this );
2833                         } catch ( Exception $ex ) {
2834                                 call_user_func( $this->errorLogger, $ex );
2835                                 $e = $e ?: $ex;
2836                         }
2837                 }
2838
2839                 if ( $e instanceof Exception ) {
2840                         throw $e; // re-throw any first exception
2841                 }
2842         }
2843
2844         final public function startAtomic( $fname = __METHOD__ ) {
2845                 if ( !$this->mTrxLevel ) {
2846                         $this->begin( $fname, self::TRANSACTION_INTERNAL );
2847                         // If DBO_TRX is set, a series of startAtomic/endAtomic pairs will result
2848                         // in all changes being in one transaction to keep requests transactional.
2849                         if ( !$this->getFlag( DBO_TRX ) ) {
2850                                 $this->mTrxAutomaticAtomic = true;
2851                         }
2852                 }
2853
2854                 $this->mTrxAtomicLevels[] = $fname;
2855         }
2856
2857         final public function endAtomic( $fname = __METHOD__ ) {
2858                 if ( !$this->mTrxLevel ) {
2859                         throw new DBUnexpectedError( $this, "No atomic transaction is open (got $fname)." );
2860                 }
2861                 if ( !$this->mTrxAtomicLevels ||
2862                         array_pop( $this->mTrxAtomicLevels ) !== $fname
2863                 ) {
2864                         throw new DBUnexpectedError( $this, "Invalid atomic section ended (got $fname)." );
2865                 }
2866
2867                 if ( !$this->mTrxAtomicLevels && $this->mTrxAutomaticAtomic ) {
2868                         $this->commit( $fname, self::FLUSHING_INTERNAL );
2869                 }
2870         }
2871
2872         final public function doAtomicSection( $fname, callable $callback ) {
2873                 $this->startAtomic( $fname );
2874                 try {
2875                         $res = call_user_func_array( $callback, [ $this, $fname ] );
2876                 } catch ( Exception $e ) {
2877                         $this->rollback( $fname, self::FLUSHING_INTERNAL );
2878                         throw $e;
2879                 }
2880                 $this->endAtomic( $fname );
2881
2882                 return $res;
2883         }
2884
2885         final public function begin( $fname = __METHOD__, $mode = self::TRANSACTION_EXPLICIT ) {
2886                 // Protect against mismatched atomic section, transaction nesting, and snapshot loss
2887                 if ( $this->mTrxLevel ) {
2888                         if ( $this->mTrxAtomicLevels ) {
2889                                 $levels = implode( ', ', $this->mTrxAtomicLevels );
2890                                 $msg = "$fname: Got explicit BEGIN while atomic section(s) $levels are open.";
2891                                 throw new DBUnexpectedError( $this, $msg );
2892                         } elseif ( !$this->mTrxAutomatic ) {
2893                                 $msg = "$fname: Explicit transaction already active (from {$this->mTrxFname}).";
2894                                 throw new DBUnexpectedError( $this, $msg );
2895                         } else {
2896                                 // @TODO: make this an exception at some point
2897                                 $msg = "$fname: Implicit transaction already active (from {$this->mTrxFname}).";
2898                                 $this->queryLogger->error( $msg );
2899                                 return; // join the main transaction set
2900                         }
2901                 } elseif ( $this->getFlag( DBO_TRX ) && $mode !== self::TRANSACTION_INTERNAL ) {
2902                         // @TODO: make this an exception at some point
2903                         $msg = "$fname: Implicit transaction expected (DBO_TRX set).";
2904                         $this->queryLogger->error( $msg );
2905                         return; // let any writes be in the main transaction
2906                 }
2907
2908                 // Avoid fatals if close() was called
2909                 $this->assertOpen();
2910
2911                 $this->doBegin( $fname );
2912                 $this->mTrxTimestamp = microtime( true );
2913                 $this->mTrxFname = $fname;
2914                 $this->mTrxDoneWrites = false;
2915                 $this->mTrxAutomatic = ( $mode === self::TRANSACTION_INTERNAL );
2916                 $this->mTrxAutomaticAtomic = false;
2917                 $this->mTrxAtomicLevels = [];
2918                 $this->mTrxShortId = sprintf( '%06x', mt_rand( 0, 0xffffff ) );
2919                 $this->mTrxWriteDuration = 0.0;
2920                 $this->mTrxWriteQueryCount = 0;
2921                 $this->mTrxWriteAdjDuration = 0.0;
2922                 $this->mTrxWriteAdjQueryCount = 0;
2923                 $this->mTrxWriteCallers = [];
2924                 // First SELECT after BEGIN will establish the snapshot in REPEATABLE-READ.
2925                 // Get an estimate of the replica DB lag before then, treating estimate staleness
2926                 // as lag itself just to be safe
2927                 $status = $this->getApproximateLagStatus();
2928                 $this->mTrxReplicaLag = $status['lag'] + ( microtime( true ) - $status['since'] );
2929         }
2930
2931         /**
2932          * Issues the BEGIN command to the database server.
2933          *
2934          * @see DatabaseBase::begin()
2935          * @param string $fname
2936          */
2937         protected function doBegin( $fname ) {
2938                 $this->query( 'BEGIN', $fname );
2939                 $this->mTrxLevel = 1;
2940         }
2941
2942         final public function commit( $fname = __METHOD__, $flush = '' ) {
2943                 if ( $this->mTrxLevel && $this->mTrxAtomicLevels ) {
2944                         // There are still atomic sections open. This cannot be ignored
2945                         $levels = implode( ', ', $this->mTrxAtomicLevels );
2946                         throw new DBUnexpectedError(
2947                                 $this,
2948                                 "$fname: Got COMMIT while atomic sections $levels are still open."
2949                         );
2950                 }
2951
2952                 if ( $flush === self::FLUSHING_INTERNAL || $flush === self::FLUSHING_ALL_PEERS ) {
2953                         if ( !$this->mTrxLevel ) {
2954                                 return; // nothing to do
2955                         } elseif ( !$this->mTrxAutomatic ) {
2956                                 throw new DBUnexpectedError(
2957                                         $this,
2958                                         "$fname: Flushing an explicit transaction, getting out of sync."
2959                                 );
2960                         }
2961                 } else {
2962                         if ( !$this->mTrxLevel ) {
2963                                 $this->queryLogger->error( "$fname: No transaction to commit, something got out of sync." );
2964                                 return; // nothing to do
2965                         } elseif ( $this->mTrxAutomatic ) {
2966                                 // @TODO: make this an exception at some point
2967                                 $msg = "$fname: Explicit commit of implicit transaction.";
2968                                 $this->queryLogger->error( $msg );
2969                                 return; // wait for the main transaction set commit round
2970                         }
2971                 }
2972
2973                 // Avoid fatals if close() was called
2974                 $this->assertOpen();
2975
2976                 $this->runOnTransactionPreCommitCallbacks();
2977                 $writeTime = $this->pendingWriteQueryDuration( self::ESTIMATE_DB_APPLY );
2978                 $this->doCommit( $fname );
2979                 if ( $this->mTrxDoneWrites ) {
2980                         $this->mDoneWrites = microtime( true );
2981                         $this->trxProfiler->transactionWritingOut(
2982                                 $this->mServer, $this->mDBname, $this->mTrxShortId, $writeTime );
2983                 }
2984
2985                 $this->runOnTransactionIdleCallbacks( self::TRIGGER_COMMIT );
2986                 $this->runTransactionListenerCallbacks( self::TRIGGER_COMMIT );
2987         }
2988
2989         /**
2990          * Issues the COMMIT command to the database server.
2991          *
2992          * @see DatabaseBase::commit()
2993          * @param string $fname
2994          */
2995         protected function doCommit( $fname ) {
2996                 if ( $this->mTrxLevel ) {
2997                         $this->query( 'COMMIT', $fname );
2998                         $this->mTrxLevel = 0;
2999                 }
3000         }
3001
3002         final public function rollback( $fname = __METHOD__, $flush = '' ) {
3003                 if ( $flush === self::FLUSHING_INTERNAL || $flush === self::FLUSHING_ALL_PEERS ) {
3004                         if ( !$this->mTrxLevel ) {
3005                                 return; // nothing to do
3006                         }
3007                 } else {
3008                         if ( !$this->mTrxLevel ) {
3009                                 $this->queryLogger->error(
3010                                         "$fname: No transaction to rollback, something got out of sync." );
3011                                 return; // nothing to do
3012                         } elseif ( $this->getFlag( DBO_TRX ) ) {
3013                                 throw new DBUnexpectedError(
3014                                         $this,
3015                                         "$fname: Expected mass rollback of all peer databases (DBO_TRX set)."
3016                                 );
3017                         }
3018                 }
3019
3020                 // Avoid fatals if close() was called
3021                 $this->assertOpen();
3022
3023                 $this->doRollback( $fname );
3024                 $this->mTrxAtomicLevels = [];
3025                 if ( $this->mTrxDoneWrites ) {
3026                         $this->trxProfiler->transactionWritingOut(
3027                                 $this->mServer, $this->mDBname, $this->mTrxShortId );
3028                 }
3029
3030                 $this->mTrxIdleCallbacks = []; // clear
3031                 $this->mTrxPreCommitCallbacks = []; // clear
3032                 $this->runOnTransactionIdleCallbacks( self::TRIGGER_ROLLBACK );
3033                 $this->runTransactionListenerCallbacks( self::TRIGGER_ROLLBACK );
3034         }
3035
3036         /**
3037          * Issues the ROLLBACK command to the database server.
3038          *
3039          * @see DatabaseBase::rollback()
3040          * @param string $fname
3041          */
3042         protected function doRollback( $fname ) {
3043                 if ( $this->mTrxLevel ) {
3044                         # Disconnects cause rollback anyway, so ignore those errors
3045                         $ignoreErrors = true;
3046                         $this->query( 'ROLLBACK', $fname, $ignoreErrors );
3047                         $this->mTrxLevel = 0;
3048                 }
3049         }
3050
3051         public function flushSnapshot( $fname = __METHOD__ ) {
3052                 if ( $this->writesOrCallbacksPending() || $this->explicitTrxActive() ) {
3053                         // This only flushes transactions to clear snapshots, not to write data
3054                         throw new DBUnexpectedError(
3055                                 $this,
3056                                 "$fname: Cannot COMMIT to clear snapshot because writes are pending."
3057                         );
3058                 }
3059
3060                 $this->commit( $fname, self::FLUSHING_INTERNAL );
3061         }
3062
3063         public function explicitTrxActive() {
3064                 return $this->mTrxLevel && ( $this->mTrxAtomicLevels || !$this->mTrxAutomatic );
3065         }
3066
3067         /**
3068          * Creates a new table with structure copied from existing table
3069          * Note that unlike most database abstraction functions, this function does not
3070          * automatically append database prefix, because it works at a lower
3071          * abstraction level.
3072          * The table names passed to this function shall not be quoted (this
3073          * function calls addIdentifierQuotes when needed).
3074          *
3075          * @param string $oldName Name of table whose structure should be copied
3076          * @param string $newName Name of table to be created
3077          * @param bool $temporary Whether the new table should be temporary
3078          * @param string $fname Calling function name
3079          * @throws RuntimeException
3080          * @return bool True if operation was successful
3081          */
3082         public function duplicateTableStructure( $oldName, $newName, $temporary = false,
3083                 $fname = __METHOD__
3084         ) {
3085                 throw new RuntimeException( __METHOD__ . ' is not implemented in descendant class' );
3086         }
3087
3088         function listTables( $prefix = null, $fname = __METHOD__ ) {
3089                 throw new RuntimeException( __METHOD__ . ' is not implemented in descendant class' );
3090         }
3091
3092         /**
3093          * Reset the views process cache set by listViews()
3094          * @since 1.22
3095          */
3096         final public function clearViewsCache() {
3097                 $this->allViews = null;
3098         }
3099
3100         /**
3101          * Lists all the VIEWs in the database
3102          *
3103          * For caching purposes the list of all views should be stored in
3104          * $this->allViews. The process cache can be cleared with clearViewsCache()
3105          *
3106          * @param string $prefix Only show VIEWs with this prefix, eg. unit_test_
3107          * @param string $fname Name of calling function
3108          * @throws RuntimeException
3109          * @return array
3110          * @since 1.22
3111          */
3112         public function listViews( $prefix = null, $fname = __METHOD__ ) {
3113                 throw new RuntimeException( __METHOD__ . ' is not implemented in descendant class' );
3114         }
3115
3116         /**
3117          * Differentiates between a TABLE and a VIEW
3118          *
3119          * @param string $name Name of the database-structure to test.
3120          * @throws RuntimeException
3121          * @return bool
3122          * @since 1.22
3123          */
3124         public function isView( $name ) {
3125                 throw new RuntimeException( __METHOD__ . ' is not implemented in descendant class' );
3126         }
3127
3128         public function timestamp( $ts = 0 ) {
3129                 return wfTimestamp( TS_MW, $ts );
3130         }
3131
3132         public function timestampOrNull( $ts = null ) {
3133                 if ( is_null( $ts ) ) {
3134                         return null;
3135                 } else {
3136                         return $this->timestamp( $ts );
3137                 }
3138         }
3139
3140         /**
3141          * Take the result from a query, and wrap it in a ResultWrapper if
3142          * necessary. Boolean values are passed through as is, to indicate success
3143          * of write queries or failure.
3144          *
3145          * Once upon a time, DatabaseBase::query() returned a bare MySQL result
3146          * resource, and it was necessary to call this function to convert it to
3147          * a wrapper. Nowadays, raw database objects are never exposed to external
3148          * callers, so this is unnecessary in external code.
3149          *
3150          * @param bool|ResultWrapper|resource|object $result
3151          * @return bool|ResultWrapper
3152          */
3153         protected function resultObject( $result ) {
3154                 if ( !$result ) {
3155                         return false;
3156                 } elseif ( $result instanceof ResultWrapper ) {
3157                         return $result;
3158                 } elseif ( $result === true ) {
3159                         // Successful write query
3160                         return $result;
3161                 } else {
3162                         return new ResultWrapper( $this, $result );
3163                 }
3164         }
3165
3166         public function ping( &$rtt = null ) {
3167                 // Avoid hitting the server if it was hit recently
3168                 if ( $this->isOpen() && ( microtime( true ) - $this->lastPing ) < self::PING_TTL ) {
3169                         if ( !func_num_args() || $this->mRTTEstimate > 0 ) {
3170                                 $rtt = $this->mRTTEstimate;
3171                                 return true; // don't care about $rtt
3172                         }
3173                 }
3174
3175                 // This will reconnect if possible or return false if not
3176                 $this->clearFlag( DBO_TRX, self::REMEMBER_PRIOR );
3177                 $ok = ( $this->query( self::PING_QUERY, __METHOD__, true ) !== false );
3178                 $this->restoreFlags( self::RESTORE_PRIOR );
3179
3180                 if ( $ok ) {
3181                         $rtt = $this->mRTTEstimate;
3182                 }
3183
3184                 return $ok;
3185         }
3186
3187         /**
3188          * @return bool
3189          */
3190         protected function reconnect() {
3191                 $this->closeConnection();
3192                 $this->mOpened = false;
3193                 $this->mConn = false;
3194                 try {
3195                         $this->open( $this->mServer, $this->mUser, $this->mPassword, $this->mDBname );
3196                         $this->lastPing = microtime( true );
3197                         $ok = true;
3198                 } catch ( DBConnectionError $e ) {
3199                         $ok = false;
3200                 }
3201
3202                 return $ok;
3203         }
3204
3205         public function getSessionLagStatus() {
3206                 return $this->getTransactionLagStatus() ?: $this->getApproximateLagStatus();
3207         }
3208
3209         /**
3210          * Get the replica DB lag when the current transaction started
3211          *
3212          * This is useful when transactions might use snapshot isolation
3213          * (e.g. REPEATABLE-READ in innodb), so the "real" lag of that data
3214          * is this lag plus transaction duration. If they don't, it is still
3215          * safe to be pessimistic. This returns null if there is no transaction.
3216          *
3217          * @return array|null ('lag': seconds or false on error, 'since': UNIX timestamp of BEGIN)
3218          * @since 1.27
3219          */
3220         public function getTransactionLagStatus() {
3221                 return $this->mTrxLevel
3222                         ? [ 'lag' => $this->mTrxReplicaLag, 'since' => $this->trxTimestamp() ]
3223                         : null;
3224         }
3225
3226         /**
3227          * Get a replica DB lag estimate for this server
3228          *
3229          * @return array ('lag': seconds or false on error, 'since': UNIX timestamp of estimate)
3230          * @since 1.27
3231          */
3232         public function getApproximateLagStatus() {
3233                 return [
3234                         'lag'   => $this->getLBInfo( 'replica' ) ? $this->getLag() : 0,
3235                         'since' => microtime( true )
3236                 ];
3237         }
3238
3239         /**
3240          * Merge the result of getSessionLagStatus() for several DBs
3241          * using the most pessimistic values to estimate the lag of
3242          * any data derived from them in combination
3243          *
3244          * This is information is useful for caching modules
3245          *
3246          * @see WANObjectCache::set()
3247          * @see WANObjectCache::getWithSetCallback()
3248          *
3249          * @param IDatabase $db1
3250          * @param IDatabase ...
3251          * @return array Map of values:
3252          *   - lag: highest lag of any of the DBs or false on error (e.g. replication stopped)
3253          *   - since: oldest UNIX timestamp of any of the DB lag estimates
3254          *   - pending: whether any of the DBs have uncommitted changes
3255          * @since 1.27
3256          */
3257         public static function getCacheSetOptions( IDatabase $db1 ) {
3258                 $res = [ 'lag' => 0, 'since' => INF, 'pending' => false ];
3259                 foreach ( func_get_args() as $db ) {
3260                         /** @var IDatabase $db */
3261                         $status = $db->getSessionLagStatus();
3262                         if ( $status['lag'] === false ) {
3263                                 $res['lag'] = false;
3264                         } elseif ( $res['lag'] !== false ) {
3265                                 $res['lag'] = max( $res['lag'], $status['lag'] );
3266                         }
3267                         $res['since'] = min( $res['since'], $status['since'] );
3268                         $res['pending'] = $res['pending'] ?: $db->writesPending();
3269                 }
3270
3271                 return $res;
3272         }
3273
3274         public function getLag() {
3275                 return 0;
3276         }
3277
3278         function maxListLen() {
3279                 return 0;
3280         }
3281
3282         public function encodeBlob( $b ) {
3283                 return $b;
3284         }
3285
3286         public function decodeBlob( $b ) {
3287                 if ( $b instanceof Blob ) {
3288                         $b = $b->fetch();
3289                 }
3290                 return $b;
3291         }
3292
3293         public function setSessionOptions( array $options ) {
3294         }
3295
3296         /**
3297          * Read and execute SQL commands from a file.
3298          *
3299          * Returns true on success, error string or exception on failure (depending
3300          * on object's error ignore settings).
3301          *
3302          * @param string $filename File name to open
3303          * @param bool|callable $lineCallback Optional function called before reading each line
3304          * @param bool|callable $resultCallback Optional function called for each MySQL result
3305          * @param bool|string $fname Calling function name or false if name should be
3306          *   generated dynamically using $filename
3307          * @param bool|callable $inputCallback Optional function called for each
3308          *   complete line sent
3309          * @return bool|string
3310          * @throws Exception
3311          */
3312         public function sourceFile(
3313                 $filename, $lineCallback = false, $resultCallback = false, $fname = false, $inputCallback = false
3314         ) {
3315                 MediaWiki\suppressWarnings();
3316                 $fp = fopen( $filename, 'r' );
3317                 MediaWiki\restoreWarnings();
3318
3319                 if ( false === $fp ) {
3320                         throw new RuntimeException( "Could not open \"{$filename}\".\n" );
3321                 }
3322
3323                 if ( !$fname ) {
3324                         $fname = __METHOD__ . "( $filename )";
3325                 }
3326
3327                 try {
3328                         $error = $this->sourceStream( $fp, $lineCallback, $resultCallback, $fname, $inputCallback );
3329                 } catch ( Exception $e ) {
3330                         fclose( $fp );
3331                         throw $e;
3332                 }
3333
3334                 fclose( $fp );
3335
3336                 return $error;
3337         }
3338
3339         public function setSchemaVars( $vars ) {
3340                 $this->mSchemaVars = $vars;
3341         }
3342
3343         /**
3344          * Read and execute commands from an open file handle.
3345          *
3346          * Returns true on success, error string or exception on failure (depending
3347          * on object's error ignore settings).
3348          *
3349          * @param resource $fp File handle
3350          * @param bool|callable $lineCallback Optional function called before reading each query
3351          * @param bool|callable $resultCallback Optional function called for each MySQL result
3352          * @param string $fname Calling function name
3353          * @param bool|callable $inputCallback Optional function called for each complete query sent
3354          * @return bool|string
3355          */
3356         public function sourceStream( $fp, $lineCallback = false, $resultCallback = false,
3357                 $fname = __METHOD__, $inputCallback = false
3358         ) {
3359                 $cmd = '';
3360
3361                 while ( !feof( $fp ) ) {
3362                         if ( $lineCallback ) {
3363                                 call_user_func( $lineCallback );
3364                         }
3365
3366                         $line = trim( fgets( $fp ) );
3367
3368                         if ( $line == '' ) {
3369                                 continue;
3370                         }
3371
3372                         if ( '-' == $line[0] && '-' == $line[1] ) {
3373                                 continue;
3374                         }
3375
3376                         if ( $cmd != '' ) {
3377                                 $cmd .= ' ';
3378                         }
3379
3380                         $done = $this->streamStatementEnd( $cmd, $line );
3381
3382                         $cmd .= "$line\n";
3383
3384                         if ( $done || feof( $fp ) ) {
3385                                 $cmd = $this->replaceVars( $cmd );
3386
3387                                 if ( ( $inputCallback && call_user_func( $inputCallback, $cmd ) ) || !$inputCallback ) {
3388                                         $res = $this->query( $cmd, $fname );
3389
3390                                         if ( $resultCallback ) {
3391                                                 call_user_func( $resultCallback, $res, $this );
3392                                         }
3393
3394                                         if ( false === $res ) {
3395                                                 $err = $this->lastError();
3396
3397                                                 return "Query \"{$cmd}\" failed with error code \"$err\".\n";
3398                                         }
3399                                 }
3400                                 $cmd = '';
3401                         }
3402                 }
3403
3404                 return true;
3405         }
3406
3407         /**
3408          * Called by sourceStream() to check if we've reached a statement end
3409          *
3410          * @param string $sql SQL assembled so far
3411          * @param string $newLine New line about to be added to $sql
3412          * @return bool Whether $newLine contains end of the statement
3413          */
3414         public function streamStatementEnd( &$sql, &$newLine ) {
3415                 if ( $this->delimiter ) {
3416                         $prev = $newLine;
3417                         $newLine = preg_replace( '/' . preg_quote( $this->delimiter, '/' ) . '$/', '', $newLine );
3418                         if ( $newLine != $prev ) {
3419                                 return true;
3420                         }
3421                 }
3422
3423                 return false;
3424         }
3425
3426         /**
3427          * Database independent variable replacement. Replaces a set of variables
3428          * in an SQL statement with their contents as given by $this->getSchemaVars().
3429          *
3430          * Supports '{$var}' `{$var}` and / *$var* / (without the spaces) style variables.
3431          *
3432          * - '{$var}' should be used for text and is passed through the database's
3433          *   addQuotes method.
3434          * - `{$var}` should be used for identifiers (e.g. table and database names).
3435          *   It is passed through the database's addIdentifierQuotes method which
3436          *   can be overridden if the database uses something other than backticks.
3437          * - / *_* / or / *$wgDBprefix* / passes the name that follows through the
3438          *   database's tableName method.
3439          * - / *i* / passes the name that follows through the database's indexName method.
3440          * - In all other cases, / *$var* / is left unencoded. Except for table options,
3441          *   its use should be avoided. In 1.24 and older, string encoding was applied.
3442          *
3443          * @param string $ins SQL statement to replace variables in
3444          * @return string The new SQL statement with variables replaced
3445          */
3446         protected function replaceVars( $ins ) {
3447                 $vars = $this->getSchemaVars();
3448                 return preg_replace_callback(
3449                         '!
3450                                 /\* (\$wgDBprefix|[_i]) \*/ (\w*) | # 1-2. tableName, indexName
3451                                 \'\{\$ (\w+) }\'                  | # 3. addQuotes
3452                                 `\{\$ (\w+) }`                    | # 4. addIdentifierQuotes
3453                                 /\*\$ (\w+) \*/                     # 5. leave unencoded
3454                         !x',
3455                         function ( $m ) use ( $vars ) {
3456                                 // Note: Because of <https://bugs.php.net/bug.php?id=51881>,
3457                                 // check for both nonexistent keys *and* the empty string.
3458                                 if ( isset( $m[1] ) && $m[1] !== '' ) {
3459                                         if ( $m[1] === 'i' ) {
3460                                                 return $this->indexName( $m[2] );
3461                                         } else {
3462                                                 return $this->tableName( $m[2] );
3463                                         }
3464                                 } elseif ( isset( $m[3] ) && $m[3] !== '' && array_key_exists( $m[3], $vars ) ) {
3465                                         return $this->addQuotes( $vars[$m[3]] );
3466                                 } elseif ( isset( $m[4] ) && $m[4] !== '' && array_key_exists( $m[4], $vars ) ) {
3467                                         return $this->addIdentifierQuotes( $vars[$m[4]] );
3468                                 } elseif ( isset( $m[5] ) && $m[5] !== '' && array_key_exists( $m[5], $vars ) ) {
3469                                         return $vars[$m[5]];
3470                                 } else {
3471                                         return $m[0];
3472                                 }
3473                         },
3474                         $ins
3475                 );
3476         }
3477
3478         /**
3479          * Get schema variables. If none have been set via setSchemaVars(), then
3480          * use some defaults from the current object.
3481          *
3482          * @return array
3483          */
3484         protected function getSchemaVars() {
3485                 if ( $this->mSchemaVars ) {
3486                         return $this->mSchemaVars;
3487                 } else {
3488                         return $this->getDefaultSchemaVars();
3489                 }
3490         }
3491
3492         /**
3493          * Get schema variables to use if none have been set via setSchemaVars().
3494          *
3495          * Override this in derived classes to provide variables for tables.sql
3496          * and SQL patch files.
3497          *
3498          * @return array
3499          */
3500         protected function getDefaultSchemaVars() {
3501                 return [];
3502         }
3503
3504         public function lockIsFree( $lockName, $method ) {
3505                 return true;
3506         }
3507
3508         public function lock( $lockName, $method, $timeout = 5 ) {
3509                 $this->mNamedLocksHeld[$lockName] = 1;
3510
3511                 return true;
3512         }
3513
3514         public function unlock( $lockName, $method ) {
3515                 unset( $this->mNamedLocksHeld[$lockName] );
3516
3517                 return true;
3518         }
3519
3520         public function getScopedLockAndFlush( $lockKey, $fname, $timeout ) {
3521                 if ( $this->writesOrCallbacksPending() ) {
3522                         // This only flushes transactions to clear snapshots, not to write data
3523                         throw new DBUnexpectedError(
3524                                 $this,
3525                                 "$fname: Cannot COMMIT to clear snapshot because writes are pending."
3526                         );
3527                 }
3528
3529                 if ( !$this->lock( $lockKey, $fname, $timeout ) ) {
3530                         return null;
3531                 }
3532
3533                 $unlocker = new ScopedCallback( function () use ( $lockKey, $fname ) {
3534                         if ( $this->trxLevel() ) {
3535                                 // There is a good chance an exception was thrown, causing any early return
3536                                 // from the caller. Let any error handler get a chance to issue rollback().
3537                                 // If there isn't one, let the error bubble up and trigger server-side rollback.
3538                                 $this->onTransactionResolution(
3539                                         function () use ( $lockKey, $fname ) {
3540                                                 $this->unlock( $lockKey, $fname );
3541                                         },
3542                                         $fname
3543                                 );
3544                         } else {
3545                                 $this->unlock( $lockKey, $fname );
3546                         }
3547                 } );
3548
3549                 $this->commit( $fname, self::FLUSHING_INTERNAL );
3550
3551                 return $unlocker;
3552         }
3553
3554         public function namedLocksEnqueue() {
3555                 return false;
3556         }
3557
3558         /**
3559          * Lock specific tables
3560          *
3561          * @param array $read Array of tables to lock for read access
3562          * @param array $write Array of tables to lock for write access
3563          * @param string $method Name of caller
3564          * @param bool $lowPriority Whether to indicate writes to be LOW PRIORITY
3565          * @return bool
3566          */
3567         public function lockTables( $read, $write, $method, $lowPriority = true ) {
3568                 return true;
3569         }
3570
3571         /**
3572          * Unlock specific tables
3573          *
3574          * @param string $method The caller
3575          * @return bool
3576          */
3577         public function unlockTables( $method ) {
3578                 return true;
3579         }
3580
3581         /**
3582          * Delete a table
3583          * @param string $tableName
3584          * @param string $fName
3585          * @return bool|ResultWrapper
3586          * @since 1.18
3587          */
3588         public function dropTable( $tableName, $fName = __METHOD__ ) {
3589                 if ( !$this->tableExists( $tableName, $fName ) ) {
3590                         return false;
3591                 }
3592                 $sql = "DROP TABLE " . $this->tableName( $tableName );
3593                 if ( $this->cascadingDeletes() ) {
3594                         $sql .= " CASCADE";
3595                 }
3596
3597                 return $this->query( $sql, $fName );
3598         }
3599
3600         /**
3601          * Get search engine class. All subclasses of this need to implement this
3602          * if they wish to use searching.
3603          *
3604          * @return string
3605          */
3606         public function getSearchEngine() {
3607                 return 'SearchEngineDummy';
3608         }
3609
3610         public function getInfinity() {
3611                 return 'infinity';
3612         }
3613
3614         public function encodeExpiry( $expiry ) {
3615                 return ( $expiry == '' || $expiry == 'infinity' || $expiry == $this->getInfinity() )
3616                         ? $this->getInfinity()
3617                         : $this->timestamp( $expiry );
3618         }
3619
3620         public function decodeExpiry( $expiry, $format = TS_MW ) {
3621                 return ( $expiry == '' || $expiry == 'infinity' || $expiry == $this->getInfinity() )
3622                         ? 'infinity'
3623                         : wfTimestamp( $format, $expiry );
3624         }
3625
3626         public function setBigSelects( $value = true ) {
3627                 // no-op
3628         }
3629
3630         public function isReadOnly() {
3631                 return ( $this->getReadOnlyReason() !== false );
3632         }
3633
3634         /**
3635          * @return string|bool Reason this DB is read-only or false if it is not
3636          */
3637         protected function getReadOnlyReason() {
3638                 $reason = $this->getLBInfo( 'readOnlyReason' );
3639
3640                 return is_string( $reason ) ? $reason : false;
3641         }
3642
3643         public function setTableAliases( array $aliases ) {
3644                 $this->tableAliases = $aliases;
3645         }
3646
3647         /**
3648          * @since 1.19
3649          * @return string
3650          */
3651         public function __toString() {
3652                 return (string)$this->mConn;
3653         }
3654
3655         /**
3656          * Run a few simple sanity checks
3657          */
3658         public function __destruct() {
3659                 if ( $this->mTrxLevel && $this->mTrxDoneWrites ) {
3660                         trigger_error( "Uncommitted DB writes (transaction from {$this->mTrxFname})." );
3661                 }
3662                 $danglingCallbacks = array_merge(
3663                         $this->mTrxIdleCallbacks,
3664                         $this->mTrxPreCommitCallbacks,
3665                         $this->mTrxEndCallbacks
3666                 );
3667                 if ( $danglingCallbacks ) {
3668                         $callers = [];
3669                         foreach ( $danglingCallbacks as $callbackInfo ) {
3670                                 $callers[] = $callbackInfo[1];
3671                         }
3672                         $callers = implode( ', ', $callers );
3673                         trigger_error( "DB transaction callbacks still pending (from $callers)." );
3674                 }
3675         }
3676 }
3677
3678 /**
3679  * @since 1.27
3680  */
3681 abstract class Database extends DatabaseBase {
3682         // B/C until nothing type hints for DatabaseBase
3683         // @TODO: finish renaming DatabaseBase => Database
3684 }