includes/db/Database.php

   1 <?php
   2 /**
   3  * @defgroup Database Database
   4  *
   5  * This file deals with database interface functions
   6  * and query specifics/optimisations.
   7  *
   8  * This program is free software; you can redistribute it and/or modify
   9  * it under the terms of the GNU General Public License as published by
  10  * the Free Software Foundation; either version 2 of the License, or
  11  * (at your option) any later version.
  12  *
  13  * This program is distributed in the hope that it will be useful,
  14  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  15  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
  16  * GNU General Public License for more details.
  17  *
  18  * You should have received a copy of the GNU General Public License along
  19  * with this program; if not, write to the Free Software Foundation, Inc.,
  20  * 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
  21  * http://www.gnu.org/copyleft/gpl.html
  22  *
  23  * @file
  24  * @ingroup Database
  25  */
  26 use Psr\Log\LoggerAwareInterface;
  27 use Psr\Log\LoggerInterface;
  28
  29 /**
  30  * Database abstraction object
  31  * @ingroup Database
  32  */
  33 abstract class DatabaseBase implements IDatabase, LoggerAwareInterface {
  34         /** Number of times to re-try an operation in case of deadlock */
  35         const DEADLOCK_TRIES = 4;
  36         /** Minimum time to wait before retry, in microseconds */
  37         const DEADLOCK_DELAY_MIN = 500000;
  38         /** Maximum time to wait before retry */
  39         const DEADLOCK_DELAY_MAX = 1500000;
  40
  41         /** How long before it is worth doing a dummy query to test the connection */
  42         const PING_TTL = 1.0;
  43         const PING_QUERY = 'SELECT 1 AS ping';
  44
  45         const TINY_WRITE_SEC = .010;
  46         const SLOW_WRITE_SEC = .500;
  47         const SMALL_WRITE_ROWS = 100;
  48
  49         /** @var string SQL query */
  50         protected $mLastQuery = '';
  51         /** @var bool */
  52         protected $mDoneWrites = false;
  53         /** @var string|bool */
  54         protected $mPHPError = false;
  55         /** @var string */
  56         protected $mServer;
  57         /** @var string */
  58         protected $mUser;
  59         /** @var string */
  60         protected $mPassword;
  61         /** @var string */
  62         protected $mDBname;
  63         /** @var bool */
  64         protected $cliMode;
  65
  66         /** @var BagOStuff APC cache */
  67         protected $srvCache;
  68         /** @var LoggerInterface */
  69         protected $connLogger;
  70         /** @var LoggerInterface */
  71         protected $queryLogger;
  72         /** @var callback Error logging callback */
  73         protected $errorLogger;
  74
  75         /** @var resource Database connection */
  76         protected $mConn = null;
  77         /** @var bool */
  78         protected $mOpened = false;
  79
  80         /** @var array[] List of (callable, method name) */
  81         protected $mTrxIdleCallbacks = [];
  82         /** @var array[] List of (callable, method name) */
  83         protected $mTrxPreCommitCallbacks = [];
  84         /** @var array[] List of (callable, method name) */
  85         protected $mTrxEndCallbacks = [];
  86         /** @var array[] Map of (name => (callable, method name)) */
  87         protected $mTrxRecurringCallbacks = [];
  88         /** @var bool Whether to suppress triggering of transaction end callbacks */
  89         protected $mTrxEndCallbacksSuppressed = false;
  90
  91         /** @var string */
  92         protected $mTablePrefix;
  93         /** @var string */
  94         protected $mSchema;
  95         /** @var integer */
  96         protected $mFlags;
  97         /** @var bool */
  98         protected $mForeign;
  99         /** @var array */
 100         protected $mLBInfo = [];
 101         /** @var bool|null */
 102         protected $mDefaultBigSelects = null;
 103         /** @var array|bool */
 104         protected $mSchemaVars = false;
 105         /** @var array */
 106         protected $mSessionVars = [];
 107         /** @var array|null */
 108         protected $preparedArgs;
 109         /** @var string|bool|null Stashed value of html_errors INI setting */
 110         protected $htmlErrors;
 111         /** @var string */
 112         protected $delimiter = ';';
 113
 114         /**
 115          * Either 1 if a transaction is active or 0 otherwise.
 116          * The other Trx fields may not be meaningfull if this is 0.
 117          *
 118          * @var int
 119          */
 120         protected $mTrxLevel = 0;
 121         /**
 122          * Either a short hexidecimal string if a transaction is active or ""
 123          *
 124          * @var string
 125          * @see DatabaseBase::mTrxLevel
 126          */
 127         protected $mTrxShortId = '';
 128         /**
 129          * The UNIX time that the transaction started. Callers can assume that if
 130          * snapshot isolation is used, then the data is *at least* up to date to that
 131          * point (possibly more up-to-date since the first SELECT defines the snapshot).
 132          *
 133          * @var float|null
 134          * @see DatabaseBase::mTrxLevel
 135          */
 136         private $mTrxTimestamp = null;
 137         /** @var float Lag estimate at the time of BEGIN */
 138         private $mTrxReplicaLag = null;
 139         /**
 140          * Remembers the function name given for starting the most recent transaction via begin().
 141          * Used to provide additional context for error reporting.
 142          *
 143          * @var string
 144          * @see DatabaseBase::mTrxLevel
 145          */
 146         private $mTrxFname = null;
 147         /**
 148          * Record if possible write queries were done in the last transaction started
 149          *
 150          * @var bool
 151          * @see DatabaseBase::mTrxLevel
 152          */
 153         private $mTrxDoneWrites = false;
 154         /**
 155          * Record if the current transaction was started implicitly due to DBO_TRX being set.
 156          *
 157          * @var bool
 158          * @see DatabaseBase::mTrxLevel
 159          */
 160         private $mTrxAutomatic = false;
 161         /**
 162          * Array of levels of atomicity within transactions
 163          *
 164          * @var array
 165          */
 166         private $mTrxAtomicLevels = [];
 167         /**
 168          * Record if the current transaction was started implicitly by DatabaseBase::startAtomic
 169          *
 170          * @var bool
 171          */
 172         private $mTrxAutomaticAtomic = false;
 173         /**
 174          * Track the write query callers of the current transaction
 175          *
 176          * @var string[]
 177          */
 178         private $mTrxWriteCallers = [];
 179         /**
 180          * @var float Seconds spent in write queries for the current transaction
 181          */
 182         private $mTrxWriteDuration = 0.0;
 183         /**
 184          * @var integer Number of write queries for the current transaction
 185          */
 186         private $mTrxWriteQueryCount = 0;
 187         /**
 188          * @var float Like mTrxWriteQueryCount but excludes lock-bound, easy to replicate, queries
 189          */
 190         private $mTrxWriteAdjDuration = 0.0;
 191         /**
 192          * @var integer Number of write queries counted in mTrxWriteAdjDuration
 193          */
 194         private $mTrxWriteAdjQueryCount = 0;
 195         /**
 196          * @var float RTT time estimate
 197          */
 198         private $mRTTEstimate = 0.0;
 199
 200         /** @var array Map of (name => 1) for locks obtained via lock() */
 201         private $mNamedLocksHeld = [];
 202
 203         /** @var IDatabase|null Lazy handle to the master DB this server replicates from */
 204         private $lazyMasterHandle;
 205
 206         /**
 207          * @since 1.21
 208          * @var resource File handle for upgrade
 209          */
 210         protected $fileHandle = null;
 211
 212         /**
 213          * @since 1.22
 214          * @var string[] Process cache of VIEWs names in the database
 215          */
 216         protected $allViews = null;
 217
 218         /** @var float UNIX timestamp */
 219         protected $lastPing = 0.0;
 220
 221         /** @var int[] Prior mFlags values */
 222         private $priorFlags = [];
 223
 224         /** @var Profiler */
 225         protected $profiler;
 226         /** @var TransactionProfiler */
 227         protected $trxProfiler;
 228
 229         /**
 230          * Constructor.
 231          *
 232          * FIXME: It is possible to construct a Database object with no associated
 233          * connection object, by specifying no parameters to __construct(). This
 234          * feature is deprecated and should be removed.
 235          *
 236          * IDatabase classes should not be constructed directly in external
 237          * code. DatabaseBase::factory() should be used instead.
 238          *
 239          * @param array $params Parameters passed from DatabaseBase::factory()
 240          */
 241         function __construct( array $params ) {
 242                 global $wgDBprefix, $wgDBmwschema;
 243
 244                 $this->srvCache = ObjectCache::getLocalServerInstance( 'hash' );
 245
 246                 $server = $params['host'];
 247                 $user = $params['user'];
 248                 $password = $params['password'];
 249                 $dbName = $params['dbname'];
 250                 $flags = $params['flags'];
 251                 $tablePrefix = $params['tablePrefix'];
 252                 $schema = $params['schema'];
 253                 $foreign = $params['foreign'];
 254
 255                 $this->cliMode = isset( $params['cliMode'] )
 256                         ? $params['cliMode']
 257                         : ( PHP_SAPI === 'cli' );
 258
 259                 $this->mFlags = $flags;
 260                 if ( $this->mFlags & DBO_DEFAULT ) {
 261                         if ( $this->cliMode ) {
 262                                 $this->mFlags &= ~DBO_TRX;
 263                         } else {
 264                                 $this->mFlags |= DBO_TRX;
 265                         }
 266                 }
 267
 268                 $this->mSessionVars = $params['variables'];
 269
 270                 /** Get the default table prefix*/
 271                 if ( $tablePrefix === 'get from global' ) {
 272                         $this->mTablePrefix = $wgDBprefix;
 273                 } else {
 274                         $this->mTablePrefix = $tablePrefix;
 275                 }
 276
 277                 /** Get the database schema*/
 278                 if ( $schema === 'get from global' ) {
 279                         $this->mSchema = $wgDBmwschema;
 280                 } else {
 281                         $this->mSchema = $schema;
 282                 }
 283
 284                 $this->mForeign = $foreign;
 285
 286                 $this->profiler = isset( $params['profiler'] )
 287                         ? $params['profiler']
 288                         : Profiler::instance(); // @TODO: remove global state
 289                 $this->trxProfiler = isset( $params['trxProfiler'] )
 290                         ? $params['trxProfiler']
 291                         : new TransactionProfiler();
 292                 $this->connLogger = isset( $params['connLogger'] )
 293                         ? $params['connLogger']
 294                         : new \Psr\Log\NullLogger();
 295                 $this->queryLogger = isset( $params['queryLogger'] )
 296                         ? $params['queryLogger']
 297                         : new \Psr\Log\NullLogger();
 298
 299                 if ( $user ) {
 300                         $this->open( $server, $user, $password, $dbName );
 301                 }
 302         }
 303
 304         /**
 305          * Given a DB type, construct the name of the appropriate child class of
 306          * IDatabase. This is designed to replace all of the manual stuff like:
 307          *    $class = 'Database' . ucfirst( strtolower( $dbType ) );
 308          * as well as validate against the canonical list of DB types we have
 309          *
 310          * This factory function is mostly useful for when you need to connect to a
 311          * database other than the MediaWiki default (such as for external auth,
 312          * an extension, et cetera). Do not use this to connect to the MediaWiki
 313          * database. Example uses in core:
 314          * @see LoadBalancer::reallyOpenConnection()
 315          * @see ForeignDBRepo::getMasterDB()
 316          * @see WebInstallerDBConnect::execute()
 317          *
 318          * @since 1.18
 319          *
 320          * @param string $dbType A possible DB type
 321          * @param array $p An array of options to pass to the constructor.
 322          *    Valid options are: host, user, password, dbname, flags, tablePrefix, schema, driver
 323          * @return IDatabase|null If the database driver or extension cannot be found
 324          * @throws InvalidArgumentException If the database driver or extension cannot be found
 325          */
 326         final public static function factory( $dbType, $p = [] ) {
 327                 global $wgCommandLineMode;
 328
 329                 $canonicalDBTypes = [
 330                         'mysql' => [ 'mysqli', 'mysql' ],
 331                         'postgres' => [],
 332                         'sqlite' => [],
 333                         'oracle' => [],
 334                         'mssql' => [],
 335                 ];
 336
 337                 $driver = false;
 338                 $dbType = strtolower( $dbType );
 339                 if ( isset( $canonicalDBTypes[$dbType] ) && $canonicalDBTypes[$dbType] ) {
 340                         $possibleDrivers = $canonicalDBTypes[$dbType];
 341                         if ( !empty( $p['driver'] ) ) {
 342                                 if ( in_array( $p['driver'], $possibleDrivers ) ) {
 343                                         $driver = $p['driver'];
 344                                 } else {
 345                                         throw new InvalidArgumentException( __METHOD__ .
 346                                                 " type '$dbType' does not support driver '{$p['driver']}'" );
 347                                 }
 348                         } else {
 349                                 foreach ( $possibleDrivers as $posDriver ) {
 350                                         if ( extension_loaded( $posDriver ) ) {
 351                                                 $driver = $posDriver;
 352                                                 break;
 353                                         }
 354                                 }
 355                         }
 356                 } else {
 357                         $driver = $dbType;
 358                 }
 359                 if ( $driver === false ) {
 360                         throw new InvalidArgumentException( __METHOD__ .
 361                                 " no viable database extension found for type '$dbType'" );
 362                 }
 363
 364                 // Determine schema defaults. Currently Microsoft SQL Server uses $wgDBmwschema,
 365                 // and everything else doesn't use a schema (e.g. null)
 366                 // Although postgres and oracle support schemas, we don't use them (yet)
 367                 // to maintain backwards compatibility
 368                 $defaultSchemas = [
 369                         'mssql' => 'get from global',
 370                 ];
 371
 372                 $class = 'Database' . ucfirst( $driver );
 373                 if ( class_exists( $class ) && is_subclass_of( $class, 'IDatabase' ) ) {
 374                         // Resolve some defaults for b/c
 375                         $p['host'] = isset( $p['host'] ) ? $p['host'] : false;
 376                         $p['user'] = isset( $p['user'] ) ? $p['user'] : false;
 377                         $p['password'] = isset( $p['password'] ) ? $p['password'] : false;
 378                         $p['dbname'] = isset( $p['dbname'] ) ? $p['dbname'] : false;
 379                         $p['flags'] = isset( $p['flags'] ) ? $p['flags'] : 0;
 380                         $p['variables'] = isset( $p['variables'] ) ? $p['variables'] : [];
 381                         $p['tablePrefix'] = isset( $p['tablePrefix'] ) ? $p['tablePrefix'] : 'get from global';
 382                         if ( !isset( $p['schema'] ) ) {
 383                                 $p['schema'] = isset( $defaultSchemas[$dbType] ) ? $defaultSchemas[$dbType] : null;
 384                         }
 385                         $p['foreign'] = isset( $p['foreign'] ) ? $p['foreign'] : false;
 386                         $p['cliMode'] = $wgCommandLineMode;
 387
 388                         $conn = new $class( $p );
 389                         if ( isset( $p['connLogger'] ) ) {
 390                                 $conn->connLogger = $p['connLogger'];
 391                         }
 392                         if ( isset( $p['queryLogger'] ) ) {
 393                                 $conn->queryLogger = $p['queryLogger'];
 394                         }
 395                         if ( isset( $p['errorLogger'] ) ) {
 396                                 $conn->errorLogger = $p['errorLogger'];
 397                         } else {
 398                                 $conn->errorLogger = [ MWExceptionHandler::class, 'logException' ];
 399                         }
 400                 } else {
 401                         $conn = null;
 402                 }
 403
 404                 return $conn;
 405         }
 406
 407         public function setLogger( LoggerInterface $logger ) {
 408                 $this->queryLogger = $logger;
 409         }
 410
 411         public function getServerInfo() {
 412                 return $this->getServerVersion();
 413         }
 414
 415         /**
 416          * @return string Command delimiter used by this database engine
 417          */
 418         public function getDelimiter() {
 419                 return $this->delimiter;
 420         }
 421
 422         /**
 423          * Boolean, controls output of large amounts of debug information.
 424          * @param bool|null $debug
 425          *   - true to enable debugging
 426          *   - false to disable debugging
 427          *   - omitted or null to do nothing
 428          *
 429          * @return bool|null Previous value of the flag
 430          */
 431         public function debug( $debug = null ) {
 432                 return wfSetBit( $this->mFlags, DBO_DEBUG, $debug );
 433         }
 434
 435         public function bufferResults( $buffer = null ) {
 436                 if ( is_null( $buffer ) ) {
 437                         return !(bool)( $this->mFlags & DBO_NOBUFFER );
 438                 } else {
 439                         return !wfSetBit( $this->mFlags, DBO_NOBUFFER, !$buffer );
 440                 }
 441         }
 442
 443         /**
 444          * Turns on (false) or off (true) the automatic generation and sending
 445          * of a "we're sorry, but there has been a database error" page on
 446          * database errors. Default is on (false). When turned off, the
 447          * code should use lastErrno() and lastError() to handle the
 448          * situation as appropriate.
 449          *
 450          * Do not use this function outside of the Database classes.
 451          *
 452          * @param null|bool $ignoreErrors
 453          * @return bool The previous value of the flag.
 454          */
 455         protected function ignoreErrors( $ignoreErrors = null ) {
 456                 return wfSetBit( $this->mFlags, DBO_IGNORE, $ignoreErrors );
 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                 return wfSetVar( $this->mTablePrefix, $prefix );
 469         }
 470
 471         public function dbSchema( $schema = null ) {
 472                 return wfSetVar( $this->mSchema, $schema );
 473         }
 474
 475         /**
 476          * Set the filehandle to copy write statements to.
 477          *
 478          * @param resource $fh File handle
 479          */
 480         public function setFileHandle( $fh ) {
 481                 $this->fileHandle = $fh;
 482         }
 483
 484         public function getLBInfo( $name = null ) {
 485                 if ( is_null( $name ) ) {
 486                         return $this->mLBInfo;
 487                 } else {
 488                         if ( array_key_exists( $name, $this->mLBInfo ) ) {
 489                                 return $this->mLBInfo[$name];
 490                         } else {
 491                                 return null;
 492                         }
 493                 }
 494         }
 495
 496         public function setLBInfo( $name, $value = null ) {
 497                 if ( is_null( $value ) ) {
 498                         $this->mLBInfo = $name;
 499                 } else {
 500                         $this->mLBInfo[$name] = $value;
 501                 }
 502         }
 503
 504         public function setLazyMasterHandle( IDatabase $conn ) {
 505                 $this->lazyMasterHandle = $conn;
 506         }
 507
 508         /**
 509          * @return IDatabase|null
 510          * @see setLazyMasterHandle()
 511          * @since 1.27
 512          */
 513         public function getLazyMasterHandle() {
 514                 return $this->lazyMasterHandle;
 515         }
 516
 517         /**
 518          * @param TransactionProfiler $profiler
 519          * @since 1.27
 520          */
 521         public function setTransactionProfiler( TransactionProfiler $profiler ) {
 522                 $this->trxProfiler = $profiler;
 523         }
 524
 525         /**
 526          * Returns true if this database supports (and uses) cascading deletes
 527          *
 528          * @return bool
 529          */
 530         public function cascadingDeletes() {
 531                 return false;
 532         }
 533
 534         /**
 535          * Returns true if this database supports (and uses) triggers (e.g. on the page table)
 536          *
 537          * @return bool
 538          */
 539         public function cleanupTriggers() {
 540                 return false;
 541         }
 542
 543         /**
 544          * Returns true if this database is strict about what can be put into an IP field.
 545          * Specifically, it uses a NULL value instead of an empty string.
 546          *
 547          * @return bool
 548          */
 549         public function strictIPs() {
 550                 return false;
 551         }
 552
 553         /**
 554          * Returns true if this database uses timestamps rather than integers
 555          *
 556          * @return bool
 557          */
 558         public function realTimestamps() {
 559                 return false;
 560         }
 561
 562         public function implicitGroupby() {
 563                 return true;
 564         }
 565
 566         public function implicitOrderby() {
 567                 return true;
 568         }
 569
 570         /**
 571          * Returns true if this database can do a native search on IP columns
 572          * e.g. this works as expected: .. WHERE rc_ip = '127.42.12.102/32';
 573          *
 574          * @return bool
 575          */
 576         public function searchableIPs() {
 577                 return false;
 578         }
 579
 580         /**
 581          * Returns true if this database can use functional indexes
 582          *
 583          * @return bool
 584          */
 585         public function functionalIndexes() {
 586                 return false;
 587         }
 588
 589         public function lastQuery() {
 590                 return $this->mLastQuery;
 591         }
 592
 593         public function doneWrites() {
 594                 return (bool)$this->mDoneWrites;
 595         }
 596
 597         public function lastDoneWrites() {
 598                 return $this->mDoneWrites ?: false;
 599         }
 600
 601         public function writesPending() {
 602                 return $this->mTrxLevel && $this->mTrxDoneWrites;
 603         }
 604
 605         public function writesOrCallbacksPending() {
 606                 return $this->mTrxLevel && (
 607                         $this->mTrxDoneWrites || $this->mTrxIdleCallbacks || $this->mTrxPreCommitCallbacks
 608                 );
 609         }
 610
 611         public function pendingWriteQueryDuration( $type = self::ESTIMATE_TOTAL ) {
 612                 if ( !$this->mTrxLevel ) {
 613                         return false;
 614                 } elseif ( !$this->mTrxDoneWrites ) {
 615                         return 0.0;
 616                 }
 617
 618                 switch ( $type ) {
 619                         case self::ESTIMATE_DB_APPLY:
 620                                 $this->ping( $rtt );
 621                                 $rttAdjTotal = $this->mTrxWriteAdjQueryCount * $rtt;
 622                                 $applyTime = max( $this->mTrxWriteAdjDuration - $rttAdjTotal, 0 );
 623                                 // For omitted queries, make them count as something at least
 624                                 $omitted = $this->mTrxWriteQueryCount - $this->mTrxWriteAdjQueryCount;
 625                                 $applyTime += self::TINY_WRITE_SEC * $omitted;
 626
 627                                 return $applyTime;
 628                         default: // everything
 629                                 return $this->mTrxWriteDuration;
 630                 }
 631         }
 632
 633         public function pendingWriteCallers() {
 634                 return $this->mTrxLevel ? $this->mTrxWriteCallers : [];
 635         }
 636
 637         public function isOpen() {
 638                 return $this->mOpened;
 639         }
 640
 641         public function setFlag( $flag, $remember = self::REMEMBER_NOTHING ) {
 642                 if ( $remember === self::REMEMBER_PRIOR ) {
 643                         array_push( $this->priorFlags, $this->mFlags );
 644                 }
 645                 $this->mFlags |= $flag;
 646         }
 647
 648         public function clearFlag( $flag, $remember = self::REMEMBER_NOTHING ) {
 649                 if ( $remember === self::REMEMBER_PRIOR ) {
 650                         array_push( $this->priorFlags, $this->mFlags );
 651                 }
 652                 $this->mFlags &= ~$flag;
 653         }
 654
 655         public function restoreFlags( $state = self::RESTORE_PRIOR ) {
 656                 if ( !$this->priorFlags ) {
 657                         return;
 658                 }
 659
 660                 if ( $state === self::RESTORE_INITIAL ) {
 661                         $this->mFlags = reset( $this->priorFlags );
 662                         $this->priorFlags = [];
 663                 } else {
 664                         $this->mFlags = array_pop( $this->priorFlags );
 665                 }
 666         }
 667
 668         public function getFlag( $flag ) {
 669                 return !!( $this->mFlags & $flag );
 670         }
 671
 672         public function getProperty( $name ) {
 673                 return $this->$name;
 674         }
 675
 676         public function getWikiID() {
 677                 if ( $this->mTablePrefix ) {
 678                         return "{$this->mDBname}-{$this->mTablePrefix}";
 679                 } else {
 680                         return $this->mDBname;
 681                 }
 682         }
 683
 684         /**
 685          * Return a path to the DBMS-specific SQL file if it exists,
 686          * otherwise default SQL file
 687          *
 688          * @param string $filename
 689          * @return string
 690          */
 691         private function getSqlFilePath( $filename ) {
 692                 global $IP;
 693                 $dbmsSpecificFilePath = "$IP/maintenance/" . $this->getType() . "/$filename";
 694                 if ( file_exists( $dbmsSpecificFilePath ) ) {
 695                         return $dbmsSpecificFilePath;
 696                 } else {
 697                         return "$IP/maintenance/$filename";
 698                 }
 699         }
 700
 701         /**
 702          * Return a path to the DBMS-specific schema file,
 703          * otherwise default to tables.sql
 704          *
 705          * @return string
 706          */
 707         public function getSchemaPath() {
 708                 return $this->getSqlFilePath( 'tables.sql' );
 709         }
 710
 711         /**
 712          * Return a path to the DBMS-specific update key file,
 713          * otherwise default to update-keys.sql
 714          *
 715          * @return string
 716          */
 717         public function getUpdateKeysPath() {
 718                 return $this->getSqlFilePath( 'update-keys.sql' );
 719         }
 720
 721         /**
 722          * Get information about an index into an object
 723          * @param string $table Table name
 724          * @param string $index Index name
 725          * @param string $fname Calling function name
 726          * @return mixed Database-specific index description class or false if the index does not exist
 727          */
 728         abstract function indexInfo( $table, $index, $fname = __METHOD__ );
 729
 730         /**
 731          * Wrapper for addslashes()
 732          *
 733          * @param string $s String to be slashed.
 734          * @return string Slashed string.
 735          */
 736         abstract function strencode( $s );
 737
 738         /**
 739          * Called by serialize. Throw an exception when DB connection is serialized.
 740          * This causes problems on some database engines because the connection is
 741          * not restored on unserialize.
 742          */
 743         public function __sleep() {
 744                 throw new RuntimeException( 'Database serialization may cause problems, since ' .
 745                         'the connection is not restored on wakeup.' );
 746         }
 747
 748         protected function installErrorHandler() {
 749                 $this->mPHPError = false;
 750                 $this->htmlErrors = ini_set( 'html_errors', '0' );
 751                 set_error_handler( [ $this, 'connectionerrorLogger' ] );
 752         }
 753
 754         /**
 755          * @return bool|string
 756          */
 757         protected function restoreErrorHandler() {
 758                 restore_error_handler();
 759                 if ( $this->htmlErrors !== false ) {
 760                         ini_set( 'html_errors', $this->htmlErrors );
 761                 }
 762                 if ( $this->mPHPError ) {
 763                         $error = preg_replace( '!\[<a.*</a>\]!', '', $this->mPHPError );
 764                         $error = preg_replace( '!^.*?:\s?(.*)$!', '$1', $error );
 765
 766                         return $error;
 767                 } else {
 768                         return false;
 769                 }
 770         }
 771
 772         /**
 773          * @param int $errno
 774          * @param string $errstr
 775          */
 776         public function connectionerrorLogger( $errno, $errstr ) {
 777                 $this->mPHPError = $errstr;
 778         }
 779
 780         /**
 781          * Create a log context to pass to PSR logging functions.
 782          *
 783          * @param array $extras Additional data to add to context
 784          * @return array
 785          */
 786         protected function getLogContext( array $extras = [] ) {
 787                 return array_merge(
 788                         [
 789                                 'db_server' => $this->mServer,
 790                                 'db_name' => $this->mDBname,
 791                                 'db_user' => $this->mUser,
 792                         ],
 793                         $extras
 794                 );
 795         }
 796
 797         public function close() {
 798                 if ( $this->mConn ) {
 799                         if ( $this->trxLevel() ) {
 800                                 $this->commit( __METHOD__, self::FLUSHING_INTERNAL );
 801                         }
 802
 803                         $closed = $this->closeConnection();
 804                         $this->mConn = false;
 805                 } elseif ( $this->mTrxIdleCallbacks || $this->mTrxEndCallbacks ) { // sanity
 806                         throw new RuntimeException( "Transaction callbacks still pending." );
 807                 } else {
 808                         $closed = true;
 809                 }
 810                 $this->mOpened = false;
 811
 812                 return $closed;
 813         }
 814
 815         /**
 816          * Make sure isOpen() returns true as a sanity check
 817          *
 818          * @throws DBUnexpectedError
 819          */
 820         protected function assertOpen() {
 821                 if ( !$this->isOpen() ) {
 822                         throw new DBUnexpectedError( $this, "DB connection was already closed." );
 823                 }
 824         }
 825
 826         /**
 827          * Closes underlying database connection
 828          * @since 1.20
 829          * @return bool Whether connection was closed successfully
 830          */
 831         abstract protected function closeConnection();
 832
 833         function reportConnectionError( $error = 'Unknown error' ) {
 834                 $myError = $this->lastError();
 835                 if ( $myError ) {
 836                         $error = $myError;
 837                 }
 838
 839                 # New method
 840                 throw new DBConnectionError( $this, $error );
 841         }
 842
 843         /**
 844          * The DBMS-dependent part of query()
 845          *
 846          * @param string $sql SQL query.
 847          * @return ResultWrapper|bool Result object to feed to fetchObject,
 848          *   fetchRow, ...; or false on failure
 849          */
 850         abstract protected function doQuery( $sql );
 851
 852         /**
 853          * Determine whether a query writes to the DB.
 854          * Should return true if unsure.
 855          *
 856          * @param string $sql
 857          * @return bool
 858          */
 859         protected function isWriteQuery( $sql ) {
 860                 return !preg_match(
 861                         '/^(?:SELECT|BEGIN|ROLLBACK|COMMIT|SET|SHOW|EXPLAIN|\(SELECT)\b/i', $sql );
 862         }
 863
 864         /**
 865          * @param $sql
 866          * @return string|null
 867          */
 868         protected function getQueryVerb( $sql ) {
 869                 return preg_match( '/^\s*([a-z]+)/i', $sql, $m ) ? strtoupper( $m[1] ) : null;
 870         }
 871
 872         /**
 873          * Determine whether a SQL statement is sensitive to isolation level.
 874          * A SQL statement is considered transactable if its result could vary
 875          * depending on the transaction isolation level. Operational commands
 876          * such as 'SET' and 'SHOW' are not considered to be transactable.
 877          *
 878          * @param string $sql
 879          * @return bool
 880          */
 881         protected function isTransactableQuery( $sql ) {
 882                 $verb = $this->getQueryVerb( $sql );
 883                 return !in_array( $verb, [ 'BEGIN', 'COMMIT', 'ROLLBACK', 'SHOW', 'SET' ], true );
 884         }
 885
 886         public function query( $sql, $fname = __METHOD__, $tempIgnore = false ) {
 887                 global $wgUser;
 888
 889                 $priorWritesPending = $this->writesOrCallbacksPending();
 890                 $this->mLastQuery = $sql;
 891
 892                 $isWrite = $this->isWriteQuery( $sql );
 893                 if ( $isWrite ) {
 894                         $reason = $this->getReadOnlyReason();
 895                         if ( $reason !== false ) {
 896                                 throw new DBReadOnlyError( $this, "Database is read-only: $reason" );
 897                         }
 898                         # Set a flag indicating that writes have been done
 899                         $this->mDoneWrites = microtime( true );
 900                 }
 901
 902                 # Add a comment for easy SHOW PROCESSLIST interpretation
 903                 if ( is_object( $wgUser ) && $wgUser->isItemLoaded( 'name' ) ) {
 904                         $userName = $wgUser->getName();
 905                         if ( mb_strlen( $userName ) > 15 ) {
 906                                 $userName = mb_substr( $userName, 0, 15 ) . '...';
 907                         }
 908                         $userName = str_replace( '/', '', $userName );
 909                 } else {
 910                         $userName = '';
 911                 }
 912
 913                 // Add trace comment to the begin of the sql string, right after the operator.
 914                 // Or, for one-word queries (like "BEGIN" or COMMIT") add it to the end (bug 42598)
 915                 $commentedSql = preg_replace( '/\s|$/', " /* $fname $userName */ ", $sql, 1 );
 916
 917                 # Start implicit transactions that wrap the request if DBO_TRX is enabled
 918                 if ( !$this->mTrxLevel && $this->getFlag( DBO_TRX )
 919                         && $this->isTransactableQuery( $sql )
 920                 ) {
 921                         $this->begin( __METHOD__ . " ($fname)", self::TRANSACTION_INTERNAL );
 922                         $this->mTrxAutomatic = true;
 923                 }
 924
 925                 # Keep track of whether the transaction has write queries pending
 926                 if ( $this->mTrxLevel && !$this->mTrxDoneWrites && $isWrite ) {
 927                         $this->mTrxDoneWrites = true;
 928                         $this->trxProfiler->transactionWritingIn(
 929                                 $this->mServer, $this->mDBname, $this->mTrxShortId );
 930                 }
 931
 932                 if ( $this->debug() ) {
 933                         $this->queryLogger->debug( "{$this->mDBname} {$commentedSql}" );
 934                 }
 935
 936                 # Avoid fatals if close() was called
 937                 $this->assertOpen();
 938
 939                 # Send the query to the server
 940                 $ret = $this->doProfiledQuery( $sql, $commentedSql, $isWrite, $fname );
 941
 942                 # Try reconnecting if the connection was lost
 943                 if ( false === $ret && $this->wasErrorReissuable() ) {
 944                         $recoverable = $this->canRecoverFromDisconnect( $sql, $priorWritesPending );
 945                         # Stash the last error values before anything might clear them
 946                         $lastError = $this->lastError();
 947                         $lastErrno = $this->lastErrno();
 948                         # Update state tracking to reflect transaction loss due to disconnection
 949                         $this->handleTransactionLoss();
 950                         if ( $this->reconnect() ) {
 951                                 $msg = __METHOD__ . ": lost connection to {$this->getServer()}; reconnected";
 952                                 $this->connLogger->warning( $msg );
 953                                 $this->queryLogger->warning(
 954                                         "$msg:\n" . ( new RuntimeException() )->getTraceAsString() );
 955
 956                                 if ( !$recoverable ) {
 957                                         # Callers may catch the exception and continue to use the DB
 958                                         $this->reportQueryError( $lastError, $lastErrno, $sql, $fname );
 959                                 } else {
 960                                         # Should be safe to silently retry the query
 961                                         $ret = $this->doProfiledQuery( $sql, $commentedSql, $isWrite, $fname );
 962                                 }
 963                         } else {
 964                                 $msg = __METHOD__ . ": lost connection to {$this->getServer()} permanently";
 965                                 $this->connLogger->error( $msg );
 966                         }
 967                 }
 968
 969                 if ( false === $ret ) {
 970                         # Deadlocks cause the entire transaction to abort, not just the statement.
 971                         # http://dev.mysql.com/doc/refman/5.7/en/innodb-error-handling.html
 972                         # https://www.postgresql.org/docs/9.1/static/explicit-locking.html
 973                         if ( $this->wasDeadlock() ) {
 974                                 if ( $this->explicitTrxActive() || $priorWritesPending ) {
 975                                         $tempIgnore = false; // not recoverable
 976                                 }
 977                                 # Update state tracking to reflect transaction loss
 978                                 $this->handleTransactionLoss();
 979                         }
 980
 981                         $this->reportQueryError(
 982                                 $this->lastError(), $this->lastErrno(), $sql, $fname, $tempIgnore );
 983                 }
 984
 985                 $res = $this->resultObject( $ret );
 986
 987                 return $res;
 988         }
 989
 990         private function doProfiledQuery( $sql, $commentedSql, $isWrite, $fname ) {
 991                 $isMaster = !is_null( $this->getLBInfo( 'master' ) );
 992                 # generalizeSQL() will probably cut down the query to reasonable
 993                 # logging size most of the time. The substr is really just a sanity check.
 994                 if ( $isMaster ) {
 995                         $queryProf = 'query-m: ' . substr( self::generalizeSQL( $sql ), 0, 255 );
 996                 } else {
 997                         $queryProf = 'query: ' . substr( self::generalizeSQL( $sql ), 0, 255 );
 998                 }
 999
1000                 # Include query transaction state
1001                 $queryProf .= $this->mTrxShortId ? " [TRX#{$this->mTrxShortId}]" : "";
1002
1003                 $startTime = microtime( true );
1004                 $this->profiler->profileIn( $queryProf );
1005                 $ret = $this->doQuery( $commentedSql );
1006                 $this->profiler->profileOut( $queryProf );
1007                 $queryRuntime = max( microtime( true ) - $startTime, 0.0 );
1008
1009                 unset( $queryProfSection ); // profile out (if set)
1010
1011                 if ( $ret !== false ) {
1012                         $this->lastPing = $startTime;
1013                         if ( $isWrite && $this->mTrxLevel ) {
1014                                 $this->updateTrxWriteQueryTime( $sql, $queryRuntime );
1015                                 $this->mTrxWriteCallers[] = $fname;
1016                         }
1017                 }
1018
1019                 if ( $sql === self::PING_QUERY ) {
1020                         $this->mRTTEstimate = $queryRuntime;
1021                 }
1022
1023                 $this->trxProfiler->recordQueryCompletion(
1024                         $queryProf, $startTime, $isWrite, $this->affectedRows()
1025                 );
1026                 MWDebug::query( $sql, $fname, $isMaster, $queryRuntime );
1027
1028                 return $ret;
1029         }
1030
1031         /**
1032          * Update the estimated run-time of a query, not counting large row lock times
1033          *
1034          * LoadBalancer can be set to rollback transactions that will create huge replication
1035          * lag. It bases this estimate off of pendingWriteQueryDuration(). Certain simple
1036          * queries, like inserting a row can take a long time due to row locking. This method
1037          * uses some simple heuristics to discount those cases.
1038          *
1039          * @param string $sql A SQL write query
1040          * @param float $runtime Total runtime, including RTT
1041          */
1042         private function updateTrxWriteQueryTime( $sql, $runtime ) {
1043                 // Whether this is indicative of replica DB runtime (except for RBR or ws_repl)
1044                 $indicativeOfReplicaRuntime = true;
1045                 if ( $runtime > self::SLOW_WRITE_SEC ) {
1046                         $verb = $this->getQueryVerb( $sql );
1047                         // insert(), upsert(), replace() are fast unless bulky in size or blocked on locks
1048                         if ( $verb === 'INSERT' ) {
1049                                 $indicativeOfReplicaRuntime = $this->affectedRows() > self::SMALL_WRITE_ROWS;
1050                         } elseif ( $verb === 'REPLACE' ) {
1051                                 $indicativeOfReplicaRuntime = $this->affectedRows() > self::SMALL_WRITE_ROWS / 2;
1052                         }
1053                 }
1054
1055                 $this->mTrxWriteDuration += $runtime;
1056                 $this->mTrxWriteQueryCount += 1;
1057                 if ( $indicativeOfReplicaRuntime ) {
1058                         $this->mTrxWriteAdjDuration += $runtime;
1059                         $this->mTrxWriteAdjQueryCount += 1;
1060                 }
1061         }
1062
1063         private function canRecoverFromDisconnect( $sql, $priorWritesPending ) {
1064                 # Transaction dropped; this can mean lost writes, or REPEATABLE-READ snapshots.
1065                 # Dropped connections also mean that named locks are automatically released.
1066                 # Only allow error suppression in autocommit mode or when the lost transaction
1067                 # didn't matter anyway (aside from DBO_TRX snapshot loss).
1068                 if ( $this->mNamedLocksHeld ) {
1069                         return false; // possible critical section violation
1070                 } elseif ( $sql === 'COMMIT' ) {
1071                         return !$priorWritesPending; // nothing written anyway? (T127428)
1072                 } elseif ( $sql === 'ROLLBACK' ) {
1073                         return true; // transaction lost...which is also what was requested :)
1074                 } elseif ( $this->explicitTrxActive() ) {
1075                         return false; // don't drop atomocity
1076                 } elseif ( $priorWritesPending ) {
1077                         return false; // prior writes lost from implicit transaction
1078                 }
1079
1080                 return true;
1081         }
1082
1083         private function handleTransactionLoss() {
1084                 $this->mTrxLevel = 0;
1085                 $this->mTrxIdleCallbacks = []; // bug 65263
1086                 $this->mTrxPreCommitCallbacks = []; // bug 65263
1087                 try {
1088                         // Handle callbacks in mTrxEndCallbacks
1089                         $this->runOnTransactionIdleCallbacks( self::TRIGGER_ROLLBACK );
1090                         $this->runTransactionListenerCallbacks( self::TRIGGER_ROLLBACK );
1091                         return null;
1092                 } catch ( Exception $e ) {
1093                         // Already logged; move on...
1094                         return $e;
1095                 }
1096         }
1097
1098         public function reportQueryError( $error, $errno, $sql, $fname, $tempIgnore = false ) {
1099                 if ( $this->ignoreErrors() || $tempIgnore ) {
1100                         $this->queryLogger->debug( "SQL ERROR (ignored): $error\n" );
1101                 } else {
1102                         $sql1line = mb_substr( str_replace( "\n", "\\n", $sql ), 0, 5 * 1024 );
1103                         $this->queryLogger->error(
1104                                 "{fname}\t{db_server}\t{errno}\t{error}\t{sql1line}",
1105                                 $this->getLogContext( [
1106                                         'method' => __METHOD__,
1107                                         'errno' => $errno,
1108                                         'error' => $error,
1109                                         'sql1line' => $sql1line,
1110                                         'fname' => $fname,
1111                                 ] )
1112                         );
1113                         $this->queryLogger->debug( "SQL ERROR: " . $error . "\n" );
1114                         throw new DBQueryError( $this, $error, $errno, $sql, $fname );
1115                 }
1116         }
1117
1118         /**
1119          * Intended to be compatible with the PEAR::DB wrapper functions.
1120          * http://pear.php.net/manual/en/package.database.db.intro-execute.php
1121          *
1122          * ? = scalar value, quoted as necessary
1123          * ! = raw SQL bit (a function for instance)
1124          * & = filename; reads the file and inserts as a blob
1125          *     (we don't use this though...)
1126          *
1127          * @param string $sql
1128          * @param string $func
1129          *
1130          * @return array
1131          */
1132         protected function prepare( $sql, $func = __METHOD__ ) {
1133                 /* MySQL doesn't support prepared statements (yet), so just
1134                  * pack up the query for reference. We'll manually replace
1135                  * the bits later.
1136                  */
1137                 return [ 'query' => $sql, 'func' => $func ];
1138         }
1139
1140         /**
1141          * Free a prepared query, generated by prepare().
1142          * @param string $prepared
1143          */
1144         protected function freePrepared( $prepared ) {
1145                 /* No-op by default */
1146         }
1147
1148         /**
1149          * Execute a prepared query with the various arguments
1150          * @param string $prepared The prepared sql
1151          * @param mixed $args Either an array here, or put scalars as varargs
1152          *
1153          * @return ResultWrapper
1154          */
1155         public function execute( $prepared, $args = null ) {
1156                 if ( !is_array( $args ) ) {
1157                         # Pull the var args
1158                         $args = func_get_args();
1159                         array_shift( $args );
1160                 }
1161
1162                 $sql = $this->fillPrepared( $prepared['query'], $args );
1163
1164                 return $this->query( $sql, $prepared['func'] );
1165         }
1166
1167         /**
1168          * For faking prepared SQL statements on DBs that don't support it directly.
1169          *
1170          * @param string $preparedQuery A 'preparable' SQL statement
1171          * @param array $args Array of Arguments to fill it with
1172          * @return string Executable SQL
1173          */
1174         public function fillPrepared( $preparedQuery, $args ) {
1175                 reset( $args );
1176                 $this->preparedArgs =& $args;
1177
1178                 return preg_replace_callback( '/(\\\\[?!&]|[?!&])/',
1179                         [ &$this, 'fillPreparedArg' ], $preparedQuery );
1180         }
1181
1182         /**
1183          * preg_callback func for fillPrepared()
1184          * The arguments should be in $this->preparedArgs and must not be touched
1185          * while we're doing this.
1186          *
1187          * @param array $matches
1188          * @throws DBUnexpectedError
1189          * @return string
1190          */
1191         protected function fillPreparedArg( $matches ) {
1192                 switch ( $matches[1] ) {
1193                         case '\\?':
1194                                 return '?';
1195                         case '\\!':
1196                                 return '!';
1197                         case '\\&':
1198                                 return '&';
1199                 }
1200
1201                 list( /* $n */, $arg ) = each( $this->preparedArgs );
1202
1203                 switch ( $matches[1] ) {
1204                         case '?':
1205                                 return $this->addQuotes( $arg );
1206                         case '!':
1207                                 return $arg;
1208                         case '&':
1209                                 # return $this->addQuotes( file_get_contents( $arg ) );
1210                                 throw new DBUnexpectedError(
1211                                         $this,
1212                                         '& mode is not implemented. If it\'s really needed, uncomment the line above.'
1213                                 );
1214                         default:
1215                                 throw new DBUnexpectedError(
1216                                         $this,
1217                                         'Received invalid match. This should never happen!'
1218                                 );
1219                 }
1220         }
1221
1222         public function freeResult( $res ) {
1223         }
1224
1225         public function selectField(
1226                 $table, $var, $cond = '', $fname = __METHOD__, $options = []
1227         ) {
1228                 if ( $var === '*' ) { // sanity
1229                         throw new DBUnexpectedError( $this, "Cannot use a * field: got '$var'" );
1230                 }
1231
1232                 if ( !is_array( $options ) ) {
1233                         $options = [ $options ];
1234                 }
1235
1236                 $options['LIMIT'] = 1;
1237
1238                 $res = $this->select( $table, $var, $cond, $fname, $options );
1239                 if ( $res === false || !$this->numRows( $res ) ) {
1240                         return false;
1241                 }
1242
1243                 $row = $this->fetchRow( $res );
1244
1245                 if ( $row !== false ) {
1246                         return reset( $row );
1247                 } else {
1248                         return false;
1249                 }
1250         }
1251
1252         public function selectFieldValues(
1253                 $table, $var, $cond = '', $fname = __METHOD__, $options = [], $join_conds = []
1254         ) {
1255                 if ( $var === '*' ) { // sanity
1256                         throw new DBUnexpectedError( $this, "Cannot use a * field" );
1257                 } elseif ( !is_string( $var ) ) { // sanity
1258                         throw new DBUnexpectedError( $this, "Cannot use an array of fields" );
1259                 }
1260
1261                 if ( !is_array( $options ) ) {
1262                         $options = [ $options ];
1263                 }
1264
1265                 $res = $this->select( $table, $var, $cond, $fname, $options, $join_conds );
1266                 if ( $res === false ) {
1267                         return false;
1268                 }
1269
1270                 $values = [];
1271                 foreach ( $res as $row ) {
1272                         $values[] = $row->$var;
1273                 }
1274
1275                 return $values;
1276         }
1277
1278         /**
1279          * Returns an optional USE INDEX clause to go after the table, and a
1280          * string to go at the end of the query.
1281          *
1282          * @param array $options Associative array of options to be turned into
1283          *   an SQL query, valid keys are listed in the function.
1284          * @return array
1285          * @see DatabaseBase::select()
1286          */
1287         public function makeSelectOptions( $options ) {
1288                 $preLimitTail = $postLimitTail = '';
1289                 $startOpts = '';
1290
1291                 $noKeyOptions = [];
1292
1293                 foreach ( $options as $key => $option ) {
1294                         if ( is_numeric( $key ) ) {
1295                                 $noKeyOptions[$option] = true;
1296                         }
1297                 }
1298
1299                 $preLimitTail .= $this->makeGroupByWithHaving( $options );
1300
1301                 $preLimitTail .= $this->makeOrderBy( $options );
1302
1303                 // if (isset($options['LIMIT'])) {
1304                 //      $tailOpts .= $this->limitResult('', $options['LIMIT'],
1305                 //              isset($options['OFFSET']) ? $options['OFFSET']
1306                 //              : false);
1307                 // }
1308
1309                 if ( isset( $noKeyOptions['FOR UPDATE'] ) ) {
1310                         $postLimitTail .= ' FOR UPDATE';
1311                 }
1312
1313                 if ( isset( $noKeyOptions['LOCK IN SHARE MODE'] ) ) {
1314                         $postLimitTail .= ' LOCK IN SHARE MODE';
1315                 }
1316
1317                 if ( isset( $noKeyOptions['DISTINCT'] ) || isset( $noKeyOptions['DISTINCTROW'] ) ) {
1318                         $startOpts .= 'DISTINCT';
1319                 }
1320
1321                 # Various MySQL extensions
1322                 if ( isset( $noKeyOptions['STRAIGHT_JOIN'] ) ) {
1323                         $startOpts .= ' /*! STRAIGHT_JOIN */';
1324                 }
1325
1326                 if ( isset( $noKeyOptions['HIGH_PRIORITY'] ) ) {
1327                         $startOpts .= ' HIGH_PRIORITY';
1328                 }
1329
1330                 if ( isset( $noKeyOptions['SQL_BIG_RESULT'] ) ) {
1331                         $startOpts .= ' SQL_BIG_RESULT';
1332                 }
1333
1334                 if ( isset( $noKeyOptions['SQL_BUFFER_RESULT'] ) ) {
1335                         $startOpts .= ' SQL_BUFFER_RESULT';
1336                 }
1337
1338                 if ( isset( $noKeyOptions['SQL_SMALL_RESULT'] ) ) {
1339                         $startOpts .= ' SQL_SMALL_RESULT';
1340                 }
1341
1342                 if ( isset( $noKeyOptions['SQL_CALC_FOUND_ROWS'] ) ) {
1343                         $startOpts .= ' SQL_CALC_FOUND_ROWS';
1344                 }
1345
1346                 if ( isset( $noKeyOptions['SQL_CACHE'] ) ) {
1347                         $startOpts .= ' SQL_CACHE';
1348                 }
1349
1350                 if ( isset( $noKeyOptions['SQL_NO_CACHE'] ) ) {
1351                         $startOpts .= ' SQL_NO_CACHE';
1352                 }
1353
1354                 if ( isset( $options['USE INDEX'] ) && is_string( $options['USE INDEX'] ) ) {
1355                         $useIndex = $this->useIndexClause( $options['USE INDEX'] );
1356                 } else {
1357                         $useIndex = '';
1358                 }
1359                 if ( isset( $options['IGNORE INDEX'] ) && is_string( $options['IGNORE INDEX'] ) ) {
1360                         $ignoreIndex = $this->ignoreIndexClause( $options['IGNORE INDEX'] );
1361                 } else {
1362                         $ignoreIndex = '';
1363                 }
1364
1365                 return [ $startOpts, $useIndex, $preLimitTail, $postLimitTail, $ignoreIndex ];
1366         }
1367
1368         /**
1369          * Returns an optional GROUP BY with an optional HAVING
1370          *
1371          * @param array $options Associative array of options
1372          * @return string
1373          * @see DatabaseBase::select()
1374          * @since 1.21
1375          */
1376         public function makeGroupByWithHaving( $options ) {
1377                 $sql = '';
1378                 if ( isset( $options['GROUP BY'] ) ) {
1379                         $gb = is_array( $options['GROUP BY'] )
1380                                 ? implode( ',', $options['GROUP BY'] )
1381                                 : $options['GROUP BY'];
1382                         $sql .= ' GROUP BY ' . $gb;
1383                 }
1384                 if ( isset( $options['HAVING'] ) ) {
1385                         $having = is_array( $options['HAVING'] )
1386                                 ? $this->makeList( $options['HAVING'], LIST_AND )
1387                                 : $options['HAVING'];
1388                         $sql .= ' HAVING ' . $having;
1389                 }
1390
1391                 return $sql;
1392         }
1393
1394         /**
1395          * Returns an optional ORDER BY
1396          *
1397          * @param array $options Associative array of options
1398          * @return string
1399          * @see DatabaseBase::select()
1400          * @since 1.21
1401          */
1402         public function makeOrderBy( $options ) {
1403                 if ( isset( $options['ORDER BY'] ) ) {
1404                         $ob = is_array( $options['ORDER BY'] )
1405                                 ? implode( ',', $options['ORDER BY'] )
1406                                 : $options['ORDER BY'];
1407
1408                         return ' ORDER BY ' . $ob;
1409                 }
1410
1411                 return '';
1412         }
1413
1414         // See IDatabase::select for the docs for this function
1415         public function select( $table, $vars, $conds = '', $fname = __METHOD__,
1416                 $options = [], $join_conds = [] ) {
1417                 $sql = $this->selectSQLText( $table, $vars, $conds, $fname, $options, $join_conds );
1418
1419                 return $this->query( $sql, $fname );
1420         }
1421
1422         public function selectSQLText( $table, $vars, $conds = '', $fname = __METHOD__,
1423                 $options = [], $join_conds = []
1424         ) {
1425                 if ( is_array( $vars ) ) {
1426                         $vars = implode( ',', $this->fieldNamesWithAlias( $vars ) );
1427                 }
1428
1429                 $options = (array)$options;
1430                 $useIndexes = ( isset( $options['USE INDEX'] ) && is_array( $options['USE INDEX'] ) )
1431                         ? $options['USE INDEX']
1432                         : [];
1433                 $ignoreIndexes = ( isset( $options['IGNORE INDEX'] ) && is_array( $options['IGNORE INDEX'] ) )
1434                         ? $options['IGNORE INDEX']
1435                         : [];
1436
1437                 if ( is_array( $table ) ) {
1438                         $from = ' FROM ' .
1439                                 $this->tableNamesWithIndexClauseOrJOIN( $table, $useIndexes, $ignoreIndexes, $join_conds );
1440                 } elseif ( $table != '' ) {
1441                         if ( $table[0] == ' ' ) {
1442                                 $from = ' FROM ' . $table;
1443                         } else {
1444                                 $from = ' FROM ' .
1445                                         $this->tableNamesWithIndexClauseOrJOIN( [ $table ], $useIndexes, $ignoreIndexes, [] );
1446                         }
1447                 } else {
1448                         $from = '';
1449                 }
1450
1451                 list( $startOpts, $useIndex, $preLimitTail, $postLimitTail, $ignoreIndex ) =
1452                         $this->makeSelectOptions( $options );
1453
1454                 if ( !empty( $conds ) ) {
1455                         if ( is_array( $conds ) ) {
1456                                 $conds = $this->makeList( $conds, LIST_AND );
1457                         }
1458                         $sql = "SELECT $startOpts $vars $from $useIndex $ignoreIndex WHERE $conds $preLimitTail";
1459                 } else {
1460                         $sql = "SELECT $startOpts $vars $from $useIndex $ignoreIndex $preLimitTail";
1461                 }
1462
1463                 if ( isset( $options['LIMIT'] ) ) {
1464                         $sql = $this->limitResult( $sql, $options['LIMIT'],
1465                                 isset( $options['OFFSET'] ) ? $options['OFFSET'] : false );
1466                 }
1467                 $sql = "$sql $postLimitTail";
1468
1469                 if ( isset( $options['EXPLAIN'] ) ) {
1470                         $sql = 'EXPLAIN ' . $sql;
1471                 }
1472
1473                 return $sql;
1474         }
1475
1476         public function selectRow( $table, $vars, $conds, $fname = __METHOD__,
1477                 $options = [], $join_conds = []
1478         ) {
1479                 $options = (array)$options;
1480                 $options['LIMIT'] = 1;
1481                 $res = $this->select( $table, $vars, $conds, $fname, $options, $join_conds );
1482
1483                 if ( $res === false ) {
1484                         return false;
1485                 }
1486
1487                 if ( !$this->numRows( $res ) ) {
1488                         return false;
1489                 }
1490
1491                 $obj = $this->fetchObject( $res );
1492
1493                 return $obj;
1494         }
1495
1496         public function estimateRowCount(
1497                 $table, $vars = '*', $conds = '', $fname = __METHOD__, $options = []
1498         ) {
1499                 $rows = 0;
1500                 $res = $this->select( $table, [ 'rowcount' => 'COUNT(*)' ], $conds, $fname, $options );
1501
1502                 if ( $res ) {
1503                         $row = $this->fetchRow( $res );
1504                         $rows = ( isset( $row['rowcount'] ) ) ? (int)$row['rowcount'] : 0;
1505                 }
1506
1507                 return $rows;
1508         }
1509
1510         public function selectRowCount(
1511                 $tables, $vars = '*', $conds = '', $fname = __METHOD__, $options = [], $join_conds = []
1512         ) {
1513                 $rows = 0;
1514                 $sql = $this->selectSQLText( $tables, '1', $conds, $fname, $options, $join_conds );
1515                 $res = $this->query( "SELECT COUNT(*) AS rowcount FROM ($sql) tmp_count", $fname );
1516
1517                 if ( $res ) {
1518                         $row = $this->fetchRow( $res );
1519                         $rows = ( isset( $row['rowcount'] ) ) ? (int)$row['rowcount'] : 0;
1520                 }
1521
1522                 return $rows;
1523         }
1524
1525         /**
1526          * Removes most variables from an SQL query and replaces them with X or N for numbers.
1527          * It's only slightly flawed. Don't use for anything important.
1528          *
1529          * @param string $sql A SQL Query
1530          *
1531          * @return string
1532          */
1533         protected static function generalizeSQL( $sql ) {
1534                 # This does the same as the regexp below would do, but in such a way
1535                 # as to avoid crashing php on some large strings.
1536                 # $sql = preg_replace( "/'([^\\\\']|\\\\.)*'|\"([^\\\\\"]|\\\\.)*\"/", "'X'", $sql );
1537
1538                 $sql = str_replace( "\\\\", '', $sql );
1539                 $sql = str_replace( "\\'", '', $sql );
1540                 $sql = str_replace( "\\\"", '', $sql );
1541                 $sql = preg_replace( "/'.*'/s", "'X'", $sql );
1542                 $sql = preg_replace( '/".*"/s', "'X'", $sql );
1543
1544                 # All newlines, tabs, etc replaced by single space
1545                 $sql = preg_replace( '/\s+/', ' ', $sql );
1546
1547                 # All numbers => N,
1548                 # except the ones surrounded by characters, e.g. l10n
1549                 $sql = preg_replace( '/-?\d+(,-?\d+)+/s', 'N,...,N', $sql );
1550                 $sql = preg_replace( '/(?<![a-zA-Z])-?\d+(?![a-zA-Z])/s', 'N', $sql );
1551
1552                 return $sql;
1553         }
1554
1555         public function fieldExists( $table, $field, $fname = __METHOD__ ) {
1556                 $info = $this->fieldInfo( $table, $field );
1557
1558                 return (bool)$info;
1559         }
1560
1561         public function indexExists( $table, $index, $fname = __METHOD__ ) {
1562                 if ( !$this->tableExists( $table ) ) {
1563                         return null;
1564                 }
1565
1566                 $info = $this->indexInfo( $table, $index, $fname );
1567                 if ( is_null( $info ) ) {
1568                         return null;
1569                 } else {
1570                         return $info !== false;
1571                 }
1572         }
1573
1574         public function tableExists( $table, $fname = __METHOD__ ) {
1575                 $table = $this->tableName( $table );
1576                 $old = $this->ignoreErrors( true );
1577                 $res = $this->query( "SELECT 1 FROM $table LIMIT 1", $fname );
1578                 $this->ignoreErrors( $old );
1579
1580                 return (bool)$res;
1581         }
1582
1583         public function indexUnique( $table, $index ) {
1584                 $indexInfo = $this->indexInfo( $table, $index );
1585
1586                 if ( !$indexInfo ) {
1587                         return null;
1588                 }
1589
1590                 return !$indexInfo[0]->Non_unique;
1591         }
1592
1593         /**
1594          * Helper for DatabaseBase::insert().
1595          *
1596          * @param array $options
1597          * @return string
1598          */
1599         protected function makeInsertOptions( $options ) {
1600                 return implode( ' ', $options );
1601         }
1602
1603         public function insert( $table, $a, $fname = __METHOD__, $options = [] ) {
1604                 # No rows to insert, easy just return now
1605                 if ( !count( $a ) ) {
1606                         return true;
1607                 }
1608
1609                 $table = $this->tableName( $table );
1610
1611                 if ( !is_array( $options ) ) {
1612                         $options = [ $options ];
1613                 }
1614
1615                 $fh = null;
1616                 if ( isset( $options['fileHandle'] ) ) {
1617                         $fh = $options['fileHandle'];
1618                 }
1619                 $options = $this->makeInsertOptions( $options );
1620
1621                 if ( isset( $a[0] ) && is_array( $a[0] ) ) {
1622                         $multi = true;
1623                         $keys = array_keys( $a[0] );
1624                 } else {
1625                         $multi = false;
1626                         $keys = array_keys( $a );
1627                 }
1628
1629                 $sql = 'INSERT ' . $options .
1630                         " INTO $table (" . implode( ',', $keys ) . ') VALUES ';
1631
1632                 if ( $multi ) {
1633                         $first = true;
1634                         foreach ( $a as $row ) {
1635                                 if ( $first ) {
1636                                         $first = false;
1637                                 } else {
1638                                         $sql .= ',';
1639                                 }
1640                                 $sql .= '(' . $this->makeList( $row ) . ')';
1641                         }
1642                 } else {
1643                         $sql .= '(' . $this->makeList( $a ) . ')';
1644                 }
1645
1646                 if ( $fh !== null && false === fwrite( $fh, $sql ) ) {
1647                         return false;
1648                 } elseif ( $fh !== null ) {
1649                         return true;
1650                 }
1651
1652                 return (bool)$this->query( $sql, $fname );
1653         }
1654
1655         /**
1656          * Make UPDATE options array for DatabaseBase::makeUpdateOptions
1657          *
1658          * @param array $options
1659          * @return array
1660          */
1661         protected function makeUpdateOptionsArray( $options ) {
1662                 if ( !is_array( $options ) ) {
1663                         $options = [ $options ];
1664                 }
1665
1666                 $opts = [];
1667
1668                 if ( in_array( 'LOW_PRIORITY', $options ) ) {
1669                         $opts[] = $this->lowPriorityOption();
1670                 }
1671
1672                 if ( in_array( 'IGNORE', $options ) ) {
1673                         $opts[] = 'IGNORE';
1674                 }
1675
1676                 return $opts;
1677         }
1678
1679         /**
1680          * Make UPDATE options for the DatabaseBase::update function
1681          *
1682          * @param array $options The options passed to DatabaseBase::update
1683          * @return string
1684          */
1685         protected function makeUpdateOptions( $options ) {
1686                 $opts = $this->makeUpdateOptionsArray( $options );
1687
1688                 return implode( ' ', $opts );
1689         }
1690
1691         function update( $table, $values, $conds, $fname = __METHOD__, $options = [] ) {
1692                 $table = $this->tableName( $table );
1693                 $opts = $this->makeUpdateOptions( $options );
1694                 $sql = "UPDATE $opts $table SET " . $this->makeList( $values, LIST_SET );
1695
1696                 if ( $conds !== [] && $conds !== '*' ) {
1697                         $sql .= " WHERE " . $this->makeList( $conds, LIST_AND );
1698                 }
1699
1700                 return $this->query( $sql, $fname );
1701         }
1702
1703         public function makeList( $a, $mode = LIST_COMMA ) {
1704                 if ( !is_array( $a ) ) {
1705                         throw new DBUnexpectedError( $this, __METHOD__ . ' called with incorrect parameters' );
1706                 }
1707
1708                 $first = true;
1709                 $list = '';
1710
1711                 foreach ( $a as $field => $value ) {
1712                         if ( !$first ) {
1713                                 if ( $mode == LIST_AND ) {
1714                                         $list .= ' AND ';
1715                                 } elseif ( $mode == LIST_OR ) {
1716                                         $list .= ' OR ';
1717                                 } else {
1718                                         $list .= ',';
1719                                 }
1720                         } else {
1721                                 $first = false;
1722                         }
1723
1724                         if ( ( $mode == LIST_AND || $mode == LIST_OR ) && is_numeric( $field ) ) {
1725                                 $list .= "($value)";
1726                         } elseif ( ( $mode == LIST_SET ) && is_numeric( $field ) ) {
1727                                 $list .= "$value";
1728                         } elseif ( ( $mode == LIST_AND || $mode == LIST_OR ) && is_array( $value ) ) {
1729                                 // Remove null from array to be handled separately if found
1730                                 $includeNull = false;
1731                                 foreach ( array_keys( $value, null, true ) as $nullKey ) {
1732                                         $includeNull = true;
1733                                         unset( $value[$nullKey] );
1734                                 }
1735                                 if ( count( $value ) == 0 && !$includeNull ) {
1736                                         throw new InvalidArgumentException( __METHOD__ . ": empty input for field $field" );
1737                                 } elseif ( count( $value ) == 0 ) {
1738                                         // only check if $field is null
1739                                         $list .= "$field IS NULL";
1740                                 } else {
1741                                         // IN clause contains at least one valid element
1742                                         if ( $includeNull ) {
1743                                                 // Group subconditions to ensure correct precedence
1744                                                 $list .= '(';
1745                                         }
1746                                         if ( count( $value ) == 1 ) {
1747                                                 // Special-case single values, as IN isn't terribly efficient
1748                                                 // Don't necessarily assume the single key is 0; we don't
1749                                                 // enforce linear numeric ordering on other arrays here.
1750                                                 $value = array_values( $value )[0];
1751                                                 $list .= $field . " = " . $this->addQuotes( $value );
1752                                         } else {
1753                                                 $list .= $field . " IN (" . $this->makeList( $value ) . ") ";
1754                                         }
1755                                         // if null present in array, append IS NULL
1756                                         if ( $includeNull ) {
1757                                                 $list .= " OR $field IS NULL)";
1758                                         }
1759                                 }
1760                         } elseif ( $value === null ) {
1761                                 if ( $mode == LIST_AND || $mode == LIST_OR ) {
1762                                         $list .= "$field IS ";
1763                                 } elseif ( $mode == LIST_SET ) {
1764                                         $list .= "$field = ";
1765                                 }
1766                                 $list .= 'NULL';
1767                         } else {
1768                                 if ( $mode == LIST_AND || $mode == LIST_OR || $mode == LIST_SET ) {
1769                                         $list .= "$field = ";
1770                                 }
1771                                 $list .= $mode == LIST_NAMES ? $value : $this->addQuotes( $value );
1772                         }
1773                 }
1774
1775                 return $list;
1776         }
1777
1778         public function makeWhereFrom2d( $data, $baseKey, $subKey ) {
1779                 $conds = [];
1780
1781                 foreach ( $data as $base => $sub ) {
1782                         if ( count( $sub ) ) {
1783                                 $conds[] = $this->makeList(
1784                                         [ $baseKey => $base, $subKey => array_keys( $sub ) ],
1785                                         LIST_AND );
1786                         }
1787                 }
1788
1789                 if ( $conds ) {
1790                         return $this->makeList( $conds, LIST_OR );
1791                 } else {
1792                         // Nothing to search for...
1793                         return false;
1794                 }
1795         }
1796
1797         /**
1798          * Return aggregated value alias
1799          *
1800          * @param array $valuedata
1801          * @param string $valuename
1802          *
1803          * @return string
1804          */
1805         public function aggregateValue( $valuedata, $valuename = 'value' ) {
1806                 return $valuename;
1807         }
1808
1809         public function bitNot( $field ) {
1810                 return "(~$field)";
1811         }
1812
1813         public function bitAnd( $fieldLeft, $fieldRight ) {
1814                 return "($fieldLeft & $fieldRight)";
1815         }
1816
1817         public function bitOr( $fieldLeft, $fieldRight ) {
1818                 return "($fieldLeft | $fieldRight)";
1819         }
1820
1821         public function buildConcat( $stringList ) {
1822                 return 'CONCAT(' . implode( ',', $stringList ) . ')';
1823         }
1824
1825         public function buildGroupConcatField(
1826                 $delim, $table, $field, $conds = '', $join_conds = []
1827         ) {
1828                 $fld = "GROUP_CONCAT($field SEPARATOR " . $this->addQuotes( $delim ) . ')';
1829
1830                 return '(' . $this->selectSQLText( $table, $fld, $conds, null, [], $join_conds ) . ')';
1831         }
1832
1833         /**
1834          * @param string $field Field or column to cast
1835          * @return string
1836          * @since 1.28
1837          */
1838         public function buildStringCast( $field ) {
1839                 return $field;
1840         }
1841
1842         public function selectDB( $db ) {
1843                 # Stub. Shouldn't cause serious problems if it's not overridden, but
1844                 # if your database engine supports a concept similar to MySQL's
1845                 # databases you may as well.
1846                 $this->mDBname = $db;
1847
1848                 return true;
1849         }
1850
1851         public function getDBname() {
1852                 return $this->mDBname;
1853         }
1854
1855         public function getServer() {
1856                 return $this->mServer;
1857         }
1858
1859         /**
1860          * Format a table name ready for use in constructing an SQL query
1861          *
1862          * This does two important things: it quotes the table names to clean them up,
1863          * and it adds a table prefix if only given a table name with no quotes.
1864          *
1865          * All functions of this object which require a table name call this function
1866          * themselves. Pass the canonical name to such functions. This is only needed
1867          * when calling query() directly.
1868          *
1869          * @note This function does not sanitize user input. It is not safe to use
1870          *   this function to escape user input.
1871          * @param string $name Database table name
1872          * @param string $format One of:
1873          *   quoted - Automatically pass the table name through addIdentifierQuotes()
1874          *            so that it can be used in a query.
1875          *   raw - Do not add identifier quotes to the table name
1876          * @return string Full database name
1877          */
1878         public function tableName( $name, $format = 'quoted' ) {
1879                 global $wgSharedDB, $wgSharedPrefix, $wgSharedTables, $wgSharedSchema;
1880                 # Skip the entire process when we have a string quoted on both ends.
1881                 # Note that we check the end so that we will still quote any use of
1882                 # use of `database`.table. But won't break things if someone wants
1883                 # to query a database table with a dot in the name.
1884                 if ( $this->isQuotedIdentifier( $name ) ) {
1885                         return $name;
1886                 }
1887
1888                 # Lets test for any bits of text that should never show up in a table
1889                 # name. Basically anything like JOIN or ON which are actually part of
1890                 # SQL queries, but may end up inside of the table value to combine
1891                 # sql. Such as how the API is doing.
1892                 # Note that we use a whitespace test rather than a \b test to avoid
1893                 # any remote case where a word like on may be inside of a table name
1894                 # surrounded by symbols which may be considered word breaks.
1895                 if ( preg_match( '/(^|\s)(DISTINCT|JOIN|ON|AS)(\s|$)/i', $name ) !== 0 ) {
1896                         return $name;
1897                 }
1898
1899                 # Split database and table into proper variables.
1900                 # We reverse the explode so that database.table and table both output
1901                 # the correct table.
1902                 $dbDetails = explode( '.', $name, 3 );
1903                 if ( count( $dbDetails ) == 3 ) {
1904                         list( $database, $schema, $table ) = $dbDetails;
1905                         # We don't want any prefix added in this case
1906                         $prefix = '';
1907                 } elseif ( count( $dbDetails ) == 2 ) {
1908                         list( $database, $table ) = $dbDetails;
1909                         # We don't want any prefix added in this case
1910                         # In dbs that support it, $database may actually be the schema
1911                         # but that doesn't affect any of the functionality here
1912                         $prefix = '';
1913                         $schema = null;
1914                 } else {
1915                         list( $table ) = $dbDetails;
1916                         if ( $wgSharedDB !== null # We have a shared database
1917                                 && $this->mForeign == false # We're not working on a foreign database
1918                                 && !$this->isQuotedIdentifier( $table ) # Prevent shared tables listing '`table`'
1919                                 && in_array( $table, $wgSharedTables ) # A shared table is selected
1920                         ) {
1921                                 $database = $wgSharedDB;
1922                                 $schema = $wgSharedSchema === null ? $this->mSchema : $wgSharedSchema;
1923                                 $prefix = $wgSharedPrefix === null ? $this->mTablePrefix : $wgSharedPrefix;
1924                         } else {
1925                                 $database = null;
1926                                 $schema = $this->mSchema; # Default schema
1927                                 $prefix = $this->mTablePrefix; # Default prefix
1928                         }
1929                 }
1930
1931                 # Quote $table and apply the prefix if not quoted.
1932                 # $tableName might be empty if this is called from Database::replaceVars()
1933                 $tableName = "{$prefix}{$table}";
1934                 if ( $format == 'quoted' && !$this->isQuotedIdentifier( $tableName ) && $tableName !== '' ) {
1935                         $tableName = $this->addIdentifierQuotes( $tableName );
1936                 }
1937
1938                 # Quote $schema and merge it with the table name if needed
1939                 if ( strlen( $schema ) ) {
1940                         if ( $format == 'quoted' && !$this->isQuotedIdentifier( $schema ) ) {
1941                                 $schema = $this->addIdentifierQuotes( $schema );
1942                         }
1943                         $tableName = $schema . '.' . $tableName;
1944                 }
1945
1946                 # Quote $database and merge it with the table name if needed
1947                 if ( $database !== null ) {
1948                         if ( $format == 'quoted' && !$this->isQuotedIdentifier( $database ) ) {
1949                                 $database = $this->addIdentifierQuotes( $database );
1950                         }
1951                         $tableName = $database . '.' . $tableName;
1952                 }
1953
1954                 return $tableName;
1955         }
1956
1957         /**
1958          * Fetch a number of table names into an array
1959          * This is handy when you need to construct SQL for joins
1960          *
1961          * Example:
1962          * extract( $dbr->tableNames( 'user', 'watchlist' ) );
1963          * $sql = "SELECT wl_namespace,wl_title FROM $watchlist,$user
1964          *         WHERE wl_user=user_id AND wl_user=$nameWithQuotes";
1965          *
1966          * @return array
1967          */
1968         public function tableNames() {
1969                 $inArray = func_get_args();
1970                 $retVal = [];
1971
1972                 foreach ( $inArray as $name ) {
1973                         $retVal[$name] = $this->tableName( $name );
1974                 }
1975
1976                 return $retVal;
1977         }
1978
1979         /**
1980          * Fetch a number of table names into an zero-indexed numerical array
1981          * This is handy when you need to construct SQL for joins
1982          *
1983          * Example:
1984          * list( $user, $watchlist ) = $dbr->tableNamesN( 'user', 'watchlist' );
1985          * $sql = "SELECT wl_namespace,wl_title FROM $watchlist,$user
1986          *         WHERE wl_user=user_id AND wl_user=$nameWithQuotes";
1987          *
1988          * @return array
1989          */
1990         public function tableNamesN() {
1991                 $inArray = func_get_args();
1992                 $retVal = [];
1993
1994                 foreach ( $inArray as $name ) {
1995                         $retVal[] = $this->tableName( $name );
1996                 }
1997
1998                 return $retVal;
1999         }
2000
2001         /**
2002          * Get an aliased table name
2003          * e.g. tableName AS newTableName
2004          *
2005          * @param string $name Table name, see tableName()
2006          * @param string|bool $alias Alias (optional)
2007          * @return string SQL name for aliased table. Will not alias a table to its own name
2008          */
2009         public function tableNameWithAlias( $name, $alias = false ) {
2010                 if ( !$alias || $alias == $name ) {
2011                         return $this->tableName( $name );
2012                 } else {
2013                         return $this->tableName( $name ) . ' ' . $this->addIdentifierQuotes( $alias );
2014                 }
2015         }
2016
2017         /**
2018          * Gets an array of aliased table names
2019          *
2020          * @param array $tables [ [alias] => table ]
2021          * @return string[] See tableNameWithAlias()
2022          */
2023         public function tableNamesWithAlias( $tables ) {
2024                 $retval = [];
2025                 foreach ( $tables as $alias => $table ) {
2026                         if ( is_numeric( $alias ) ) {
2027                                 $alias = $table;
2028                         }
2029                         $retval[] = $this->tableNameWithAlias( $table, $alias );
2030                 }
2031
2032                 return $retval;
2033         }
2034
2035         /**
2036          * Get an aliased field name
2037          * e.g. fieldName AS newFieldName
2038          *
2039          * @param string $name Field name
2040          * @param string|bool $alias Alias (optional)
2041          * @return string SQL name for aliased field. Will not alias a field to its own name
2042          */
2043         public function fieldNameWithAlias( $name, $alias = false ) {
2044                 if ( !$alias || (string)$alias === (string)$name ) {
2045                         return $name;
2046                 } else {
2047                         return $name . ' AS ' . $this->addIdentifierQuotes( $alias ); // PostgreSQL needs AS
2048                 }
2049         }
2050
2051         /**
2052          * Gets an array of aliased field names
2053          *
2054          * @param array $fields [ [alias] => field ]
2055          * @return string[] See fieldNameWithAlias()
2056          */
2057         public function fieldNamesWithAlias( $fields ) {
2058                 $retval = [];
2059                 foreach ( $fields as $alias => $field ) {
2060                         if ( is_numeric( $alias ) ) {
2061                                 $alias = $field;
2062                         }
2063                         $retval[] = $this->fieldNameWithAlias( $field, $alias );
2064                 }
2065
2066                 return $retval;
2067         }
2068
2069         /**
2070          * Get the aliased table name clause for a FROM clause
2071          * which might have a JOIN and/or USE INDEX or IGNORE INDEX clause
2072          *
2073          * @param array $tables ( [alias] => table )
2074          * @param array $use_index Same as for select()
2075          * @param array $ignore_index Same as for select()
2076          * @param array $join_conds Same as for select()
2077          * @return string
2078          */
2079         protected function tableNamesWithIndexClauseOrJOIN(
2080                 $tables, $use_index = [], $ignore_index = [], $join_conds = []
2081         ) {
2082                 $ret = [];
2083                 $retJOIN = [];
2084                 $use_index = (array)$use_index;
2085                 $ignore_index = (array)$ignore_index;
2086                 $join_conds = (array)$join_conds;
2087
2088                 foreach ( $tables as $alias => $table ) {
2089                         if ( !is_string( $alias ) ) {
2090                                 // No alias? Set it equal to the table name
2091                                 $alias = $table;
2092                         }
2093                         // Is there a JOIN clause for this table?
2094                         if ( isset( $join_conds[$alias] ) ) {
2095                                 list( $joinType, $conds ) = $join_conds[$alias];
2096                                 $tableClause = $joinType;
2097                                 $tableClause .= ' ' . $this->tableNameWithAlias( $table, $alias );
2098                                 if ( isset( $use_index[$alias] ) ) { // has USE INDEX?
2099                                         $use = $this->useIndexClause( implode( ',', (array)$use_index[$alias] ) );
2100                                         if ( $use != '' ) {
2101                                                 $tableClause .= ' ' . $use;
2102                                         }
2103                                 }
2104                                 if ( isset( $ignore_index[$alias] ) ) { // has IGNORE INDEX?
2105                                         $ignore = $this->ignoreIndexClause( implode( ',', (array)$ignore_index[$alias] ) );
2106                                         if ( $ignore != '' ) {
2107                                                 $tableClause .= ' ' . $ignore;
2108                                         }
2109                                 }
2110                                 $on = $this->makeList( (array)$conds, LIST_AND );
2111                                 if ( $on != '' ) {
2112                                         $tableClause .= ' ON (' . $on . ')';
2113                                 }
2114
2115                                 $retJOIN[] = $tableClause;
2116                         } elseif ( isset( $use_index[$alias] ) ) {
2117                                 // Is there an INDEX clause for this table?
2118                                 $tableClause = $this->tableNameWithAlias( $table, $alias );
2119                                 $tableClause .= ' ' . $this->useIndexClause(
2120                                         implode( ',', (array)$use_index[$alias] )
2121                                 );
2122
2123                                 $ret[] = $tableClause;
2124                         } elseif ( isset( $ignore_index[$alias] ) ) {
2125                                 // Is there an INDEX clause for this table?
2126                                 $tableClause = $this->tableNameWithAlias( $table, $alias );
2127                                 $tableClause .= ' ' . $this->ignoreIndexClause(
2128                                         implode( ',', (array)$ignore_index[$alias] )
2129                                 );
2130
2131                                 $ret[] = $tableClause;
2132                         } else {
2133                                 $tableClause = $this->tableNameWithAlias( $table, $alias );
2134
2135                                 $ret[] = $tableClause;
2136                         }
2137                 }
2138
2139                 // We can't separate explicit JOIN clauses with ',', use ' ' for those
2140                 $implicitJoins = !empty( $ret ) ? implode( ',', $ret ) : "";
2141                 $explicitJoins = !empty( $retJOIN ) ? implode( ' ', $retJOIN ) : "";
2142
2143                 // Compile our final table clause
2144                 return implode( ' ', [ $implicitJoins, $explicitJoins ] );
2145         }
2146
2147         /**
2148          * Get the name of an index in a given table.
2149          *
2150          * @param string $index
2151          * @return string
2152          */
2153         protected function indexName( $index ) {
2154                 // Backwards-compatibility hack
2155                 $renamed = [
2156                         'ar_usertext_timestamp' => 'usertext_timestamp',
2157                         'un_user_id' => 'user_id',
2158                         'un_user_ip' => 'user_ip',
2159                 ];
2160
2161                 if ( isset( $renamed[$index] ) ) {
2162                         return $renamed[$index];
2163                 } else {
2164                         return $index;
2165                 }
2166         }
2167
2168         public function addQuotes( $s ) {
2169                 if ( $s instanceof Blob ) {
2170                         $s = $s->fetch();
2171                 }
2172                 if ( $s === null ) {
2173                         return 'NULL';
2174                 } else {
2175                         # This will also quote numeric values. This should be harmless,
2176                         # and protects against weird problems that occur when they really
2177                         # _are_ strings such as article titles and string->number->string
2178                         # conversion is not 1:1.
2179                         return "'" . $this->strencode( $s ) . "'";
2180                 }
2181         }
2182
2183         /**
2184          * Quotes an identifier using `backticks` or "double quotes" depending on the database type.
2185          * MySQL uses `backticks` while basically everything else uses double quotes.
2186          * Since MySQL is the odd one out here the double quotes are our generic
2187          * and we implement backticks in DatabaseMysql.
2188          *
2189          * @param string $s
2190          * @return string
2191          */
2192         public function addIdentifierQuotes( $s ) {
2193                 return '"' . str_replace( '"', '""', $s ) . '"';
2194         }
2195
2196         /**
2197          * Returns if the given identifier looks quoted or not according to
2198          * the database convention for quoting identifiers .
2199          *
2200          * @note Do not use this to determine if untrusted input is safe.
2201          *   A malicious user can trick this function.
2202          * @param string $name
2203          * @return bool
2204          */
2205         public function isQuotedIdentifier( $name ) {
2206                 return $name[0] == '"' && substr( $name, -1, 1 ) == '"';
2207         }
2208
2209         /**
2210          * @param string $s
2211          * @return string
2212          */
2213         protected function escapeLikeInternal( $s ) {
2214                 return addcslashes( $s, '\%_' );
2215         }
2216
2217         public function buildLike() {
2218                 $params = func_get_args();
2219
2220                 if ( count( $params ) > 0 && is_array( $params[0] ) ) {
2221                         $params = $params[0];
2222                 }
2223
2224                 $s = '';
2225
2226                 foreach ( $params as $value ) {
2227                         if ( $value instanceof LikeMatch ) {
2228                                 $s .= $value->toString();
2229                         } else {
2230                                 $s .= $this->escapeLikeInternal( $value );
2231                         }
2232                 }
2233
2234                 return " LIKE {$this->addQuotes( $s )} ";
2235         }
2236
2237         public function anyChar() {
2238                 return new LikeMatch( '_' );
2239         }
2240
2241         public function anyString() {
2242                 return new LikeMatch( '%' );
2243         }
2244
2245         public function nextSequenceValue( $seqName ) {
2246                 return null;
2247         }
2248
2249         /**
2250          * USE INDEX clause. Unlikely to be useful for anything but MySQL. This
2251          * is only needed because a) MySQL must be as efficient as possible due to
2252          * its use on Wikipedia, and b) MySQL 4.0 is kind of dumb sometimes about
2253          * which index to pick. Anyway, other databases might have different
2254          * indexes on a given table. So don't bother overriding this unless you're
2255          * MySQL.
2256          * @param string $index
2257          * @return string
2258          */
2259         public function useIndexClause( $index ) {
2260                 return '';
2261         }
2262
2263         /**
2264          * IGNORE INDEX clause. Unlikely to be useful for anything but MySQL. This
2265          * is only needed because a) MySQL must be as efficient as possible due to
2266          * its use on Wikipedia, and b) MySQL 4.0 is kind of dumb sometimes about
2267          * which index to pick. Anyway, other databases might have different
2268          * indexes on a given table. So don't bother overriding this unless you're
2269          * MySQL.
2270          * @param string $index
2271          * @return string
2272          */
2273         public function ignoreIndexClause( $index ) {
2274                 return '';
2275         }
2276
2277         public function replace( $table, $uniqueIndexes, $rows, $fname = __METHOD__ ) {
2278                 $quotedTable = $this->tableName( $table );
2279
2280                 if ( count( $rows ) == 0 ) {
2281                         return;
2282                 }
2283
2284                 # Single row case
2285                 if ( !is_array( reset( $rows ) ) ) {
2286                         $rows = [ $rows ];
2287                 }
2288
2289                 // @FXIME: this is not atomic, but a trx would break affectedRows()
2290                 foreach ( $rows as $row ) {
2291                         # Delete rows which collide
2292                         if ( $uniqueIndexes ) {
2293                                 $sql = "DELETE FROM $quotedTable WHERE ";
2294                                 $first = true;
2295                                 foreach ( $uniqueIndexes as $index ) {
2296                                         if ( $first ) {
2297                                                 $first = false;
2298                                                 $sql .= '( ';
2299                                         } else {
2300                                                 $sql .= ' ) OR ( ';
2301                                         }
2302                                         if ( is_array( $index ) ) {
2303                                                 $first2 = true;
2304                                                 foreach ( $index as $col ) {
2305                                                         if ( $first2 ) {
2306                                                                 $first2 = false;
2307                                                         } else {
2308                                                                 $sql .= ' AND ';
2309                                                         }
2310                                                         $sql .= $col . '=' . $this->addQuotes( $row[$col] );
2311                                                 }
2312                                         } else {
2313                                                 $sql .= $index . '=' . $this->addQuotes( $row[$index] );
2314                                         }
2315                                 }
2316                                 $sql .= ' )';
2317                                 $this->query( $sql, $fname );
2318                         }
2319
2320                         # Now insert the row
2321                         $this->insert( $table, $row, $fname );
2322                 }
2323         }
2324
2325         /**
2326          * REPLACE query wrapper for MySQL and SQLite, which have a native REPLACE
2327          * statement.
2328          *
2329          * @param string $table Table name
2330          * @param array|string $rows Row(s) to insert
2331          * @param string $fname Caller function name
2332          *
2333          * @return ResultWrapper
2334          */
2335         protected function nativeReplace( $table, $rows, $fname ) {
2336                 $table = $this->tableName( $table );
2337
2338                 # Single row case
2339                 if ( !is_array( reset( $rows ) ) ) {
2340                         $rows = [ $rows ];
2341                 }
2342
2343                 $sql = "REPLACE INTO $table (" . implode( ',', array_keys( $rows[0] ) ) . ') VALUES ';
2344                 $first = true;
2345
2346                 foreach ( $rows as $row ) {
2347                         if ( $first ) {
2348                                 $first = false;
2349                         } else {
2350                                 $sql .= ',';
2351                         }
2352
2353                         $sql .= '(' . $this->makeList( $row ) . ')';
2354                 }
2355
2356                 return $this->query( $sql, $fname );
2357         }
2358
2359         public function upsert( $table, array $rows, array $uniqueIndexes, array $set,
2360                 $fname = __METHOD__
2361         ) {
2362                 if ( !count( $rows ) ) {
2363                         return true; // nothing to do
2364                 }
2365
2366                 if ( !is_array( reset( $rows ) ) ) {
2367                         $rows = [ $rows ];
2368                 }
2369
2370                 if ( count( $uniqueIndexes ) ) {
2371                         $clauses = []; // list WHERE clauses that each identify a single row
2372                         foreach ( $rows as $row ) {
2373                                 foreach ( $uniqueIndexes as $index ) {
2374                                         $index = is_array( $index ) ? $index : [ $index ]; // columns
2375                                         $rowKey = []; // unique key to this row
2376                                         foreach ( $index as $column ) {
2377                                                 $rowKey[$column] = $row[$column];
2378                                         }
2379                                         $clauses[] = $this->makeList( $rowKey, LIST_AND );
2380                                 }
2381                         }
2382                         $where = [ $this->makeList( $clauses, LIST_OR ) ];
2383                 } else {
2384                         $where = false;
2385                 }
2386
2387                 $useTrx = !$this->mTrxLevel;
2388                 if ( $useTrx ) {
2389                         $this->begin( $fname, self::TRANSACTION_INTERNAL );
2390                 }
2391                 try {
2392                         # Update any existing conflicting row(s)
2393                         if ( $where !== false ) {
2394                                 $ok = $this->update( $table, $set, $where, $fname );
2395                         } else {
2396                                 $ok = true;
2397                         }
2398                         # Now insert any non-conflicting row(s)
2399                         $ok = $this->insert( $table, $rows, $fname, [ 'IGNORE' ] ) && $ok;
2400                 } catch ( Exception $e ) {
2401                         if ( $useTrx ) {
2402                                 $this->rollback( $fname, self::FLUSHING_INTERNAL );
2403                         }
2404                         throw $e;
2405                 }
2406                 if ( $useTrx ) {
2407                         $this->commit( $fname, self::FLUSHING_INTERNAL );
2408                 }
2409
2410                 return $ok;
2411         }
2412
2413         public function deleteJoin( $delTable, $joinTable, $delVar, $joinVar, $conds,
2414                 $fname = __METHOD__
2415         ) {
2416                 if ( !$conds ) {
2417                         throw new DBUnexpectedError( $this, __METHOD__ . ' called with empty $conds' );
2418                 }
2419
2420                 $delTable = $this->tableName( $delTable );
2421                 $joinTable = $this->tableName( $joinTable );
2422                 $sql = "DELETE FROM $delTable WHERE $delVar IN (SELECT $joinVar FROM $joinTable ";
2423                 if ( $conds != '*' ) {
2424                         $sql .= 'WHERE ' . $this->makeList( $conds, LIST_AND );
2425                 }
2426                 $sql .= ')';
2427
2428                 $this->query( $sql, $fname );
2429         }
2430
2431         /**
2432          * Returns the size of a text field, or -1 for "unlimited"
2433          *
2434          * @param string $table
2435          * @param string $field
2436          * @return int
2437          */
2438         public function textFieldSize( $table, $field ) {
2439                 $table = $this->tableName( $table );
2440                 $sql = "SHOW COLUMNS FROM $table LIKE \"$field\";";
2441                 $res = $this->query( $sql, __METHOD__ );
2442                 $row = $this->fetchObject( $res );
2443
2444                 $m = [];
2445
2446                 if ( preg_match( '/\((.*)\)/', $row->Type, $m ) ) {
2447                         $size = $m[1];
2448                 } else {
2449                         $size = -1;
2450                 }
2451
2452                 return $size;
2453         }
2454
2455         /**
2456          * A string to insert into queries to show that they're low-priority, like
2457          * MySQL's LOW_PRIORITY. If no such feature exists, return an empty
2458          * string and nothing bad should happen.
2459          *
2460          * @return string Returns the text of the low priority option if it is
2461          *   supported, or a blank string otherwise
2462          */
2463         public function lowPriorityOption() {
2464                 return '';
2465         }
2466
2467         public function delete( $table, $conds, $fname = __METHOD__ ) {
2468                 if ( !$conds ) {
2469                         throw new DBUnexpectedError( $this, __METHOD__ . ' called with no conditions' );
2470                 }
2471
2472                 $table = $this->tableName( $table );
2473                 $sql = "DELETE FROM $table";
2474
2475                 if ( $conds != '*' ) {
2476                         if ( is_array( $conds ) ) {
2477                                 $conds = $this->makeList( $conds, LIST_AND );
2478                         }
2479                         $sql .= ' WHERE ' . $conds;
2480                 }
2481
2482                 return $this->query( $sql, $fname );
2483         }
2484
2485         public function insertSelect(
2486                 $destTable, $srcTable, $varMap, $conds,
2487                 $fname = __METHOD__, $insertOptions = [], $selectOptions = []
2488         ) {
2489                 if ( $this->cliMode ) {
2490                         // For massive migrations with downtime, we don't want to select everything
2491                         // into memory and OOM, so do all this native on the server side if possible.
2492                         return $this->nativeInsertSelect(
2493                                 $destTable,
2494                                 $srcTable,
2495                                 $varMap,
2496                                 $conds,
2497                                 $fname,
2498                                 $insertOptions,
2499                                 $selectOptions
2500                         );
2501                 }
2502
2503                 // For web requests, do a locking SELECT and then INSERT. This puts the SELECT burden
2504                 // on only the master (without needing row-based-replication). It also makes it easy to
2505                 // know how big the INSERT is going to be.
2506                 $fields = [];
2507                 foreach ( $varMap as $dstColumn => $sourceColumnOrSql ) {
2508                         $fields[] = $this->fieldNameWithAlias( $sourceColumnOrSql, $dstColumn );
2509                 }
2510                 $selectOptions[] = 'FOR UPDATE';
2511                 $res = $this->select( $srcTable, implode( ',', $fields ), $conds, $fname, $selectOptions );
2512                 if ( !$res ) {
2513                         return false;
2514                 }
2515
2516                 $rows = [];
2517                 foreach ( $res as $row ) {
2518                         $rows[] = (array)$row;
2519                 }
2520
2521                 return $this->insert( $destTable, $rows, $fname, $insertOptions );
2522         }
2523
2524         public function nativeInsertSelect( $destTable, $srcTable, $varMap, $conds,
2525                 $fname = __METHOD__,
2526                 $insertOptions = [], $selectOptions = []
2527         ) {
2528                 $destTable = $this->tableName( $destTable );
2529
2530                 if ( !is_array( $insertOptions ) ) {
2531                         $insertOptions = [ $insertOptions ];
2532                 }
2533
2534                 $insertOptions = $this->makeInsertOptions( $insertOptions );
2535
2536                 if ( !is_array( $selectOptions ) ) {
2537                         $selectOptions = [ $selectOptions ];
2538                 }
2539
2540                 list( $startOpts, $useIndex, $tailOpts, $ignoreIndex ) = $this->makeSelectOptions(
2541                         $selectOptions );
2542
2543                 if ( is_array( $srcTable ) ) {
2544                         $srcTable = implode( ',', array_map( [ &$this, 'tableName' ], $srcTable ) );
2545                 } else {
2546                         $srcTable = $this->tableName( $srcTable );
2547                 }
2548
2549                 $sql = "INSERT $insertOptions INTO $destTable (" . implode( ',', array_keys( $varMap ) ) . ')' .
2550                         " SELECT $startOpts " . implode( ',', $varMap ) .
2551                         " FROM $srcTable $useIndex $ignoreIndex ";
2552
2553                 if ( $conds != '*' ) {
2554                         if ( is_array( $conds ) ) {
2555                                 $conds = $this->makeList( $conds, LIST_AND );
2556                         }
2557                         $sql .= " WHERE $conds";
2558                 }
2559
2560                 $sql .= " $tailOpts";
2561
2562                 return $this->query( $sql, $fname );
2563         }
2564
2565         /**
2566          * Construct a LIMIT query with optional offset. This is used for query
2567          * pages. The SQL should be adjusted so that only the first $limit rows
2568          * are returned. If $offset is provided as well, then the first $offset
2569          * rows should be discarded, and the next $limit rows should be returned.
2570          * If the result of the query is not ordered, then the rows to be returned
2571          * are theoretically arbitrary.
2572          *
2573          * $sql is expected to be a SELECT, if that makes a difference.
2574          *
2575          * The version provided by default works in MySQL and SQLite. It will very
2576          * likely need to be overridden for most other DBMSes.
2577          *
2578          * @param string $sql SQL query we will append the limit too
2579          * @param int $limit The SQL limit
2580          * @param int|bool $offset The SQL offset (default false)
2581          * @throws DBUnexpectedError
2582          * @return string
2583          */
2584         public function limitResult( $sql, $limit, $offset = false ) {
2585                 if ( !is_numeric( $limit ) ) {
2586                         throw new DBUnexpectedError( $this, "Invalid non-numeric limit passed to limitResult()\n" );
2587                 }
2588
2589                 return "$sql LIMIT "
2590                         . ( ( is_numeric( $offset ) && $offset != 0 ) ? "{$offset}," : "" )
2591                         . "{$limit} ";
2592         }
2593
2594         public function unionSupportsOrderAndLimit() {
2595                 return true; // True for almost every DB supported
2596         }
2597
2598         public function unionQueries( $sqls, $all ) {
2599                 $glue = $all ? ') UNION ALL (' : ') UNION (';
2600
2601                 return '(' . implode( $glue, $sqls ) . ')';
2602         }
2603
2604         public function conditional( $cond, $trueVal, $falseVal ) {
2605                 if ( is_array( $cond ) ) {
2606                         $cond = $this->makeList( $cond, LIST_AND );
2607                 }
2608
2609                 return " (CASE WHEN $cond THEN $trueVal ELSE $falseVal END) ";
2610         }
2611
2612         public function strreplace( $orig, $old, $new ) {
2613                 return "REPLACE({$orig}, {$old}, {$new})";
2614         }
2615
2616         public function getServerUptime() {
2617                 return 0;
2618         }
2619
2620         public function wasDeadlock() {
2621                 return false;
2622         }
2623
2624         public function wasLockTimeout() {
2625                 return false;
2626         }
2627
2628         public function wasErrorReissuable() {
2629                 return false;
2630         }
2631
2632         public function wasReadOnlyError() {
2633                 return false;
2634         }
2635
2636         /**
2637          * Determines if the given query error was a connection drop
2638          * STUB
2639          *
2640          * @param integer|string $errno
2641          * @return bool
2642          */
2643         public function wasConnectionError( $errno ) {
2644                 return false;
2645         }
2646
2647         /**
2648          * Perform a deadlock-prone transaction.
2649          *
2650          * This function invokes a callback function to perform a set of write
2651          * queries. If a deadlock occurs during the processing, the transaction
2652          * will be rolled back and the callback function will be called again.
2653          *
2654          * Avoid using this method outside of Job or Maintenance classes.
2655          *
2656          * Usage:
2657          *   $dbw->deadlockLoop( callback, ... );
2658          *
2659          * Extra arguments are passed through to the specified callback function.
2660          * This method requires that no transactions are already active to avoid
2661          * causing premature commits or exceptions.
2662          *
2663          * Returns whatever the callback function returned on its successful,
2664          * iteration, or false on error, for example if the retry limit was
2665          * reached.
2666          *
2667          * @return mixed
2668          * @throws DBUnexpectedError
2669          * @throws Exception
2670          */
2671         public function deadlockLoop() {
2672                 $args = func_get_args();
2673                 $function = array_shift( $args );
2674                 $tries = self::DEADLOCK_TRIES;
2675
2676                 $this->begin( __METHOD__ );
2677
2678                 $retVal = null;
2679                 /** @var Exception $e */
2680                 $e = null;
2681                 do {
2682                         try {
2683                                 $retVal = call_user_func_array( $function, $args );
2684                                 break;
2685                         } catch ( DBQueryError $e ) {
2686                                 if ( $this->wasDeadlock() ) {
2687                                         // Retry after a randomized delay
2688                                         usleep( mt_rand( self::DEADLOCK_DELAY_MIN, self::DEADLOCK_DELAY_MAX ) );
2689                                 } else {
2690                                         // Throw the error back up
2691                                         throw $e;
2692                                 }
2693                         }
2694                 } while ( --$tries > 0 );
2695
2696                 if ( $tries <= 0 ) {
2697                         // Too many deadlocks; give up
2698                         $this->rollback( __METHOD__ );
2699                         throw $e;
2700                 } else {
2701                         $this->commit( __METHOD__ );
2702
2703                         return $retVal;
2704                 }
2705         }
2706
2707         public function masterPosWait( DBMasterPos $pos, $timeout ) {
2708                 # Real waits are implemented in the subclass.
2709                 return 0;
2710         }
2711
2712         public function getSlavePos() {
2713                 # Stub
2714                 return false;
2715         }
2716
2717         public function getMasterPos() {
2718                 # Stub
2719                 return false;
2720         }
2721
2722         public function serverIsReadOnly() {
2723                 return false;
2724         }
2725
2726         final public function onTransactionResolution( callable $callback ) {
2727                 if ( !$this->mTrxLevel ) {
2728                         throw new DBUnexpectedError( $this, "No transaction is active." );
2729                 }
2730                 $this->mTrxEndCallbacks[] = [ $callback, wfGetCaller() ];
2731         }
2732
2733         final public function onTransactionIdle( callable $callback ) {
2734                 $this->mTrxIdleCallbacks[] = [ $callback, wfGetCaller() ];
2735                 if ( !$this->mTrxLevel ) {
2736                         $this->runOnTransactionIdleCallbacks( self::TRIGGER_IDLE );
2737                 }
2738         }
2739
2740         final public function onTransactionPreCommitOrIdle( callable $callback ) {
2741                 if ( $this->mTrxLevel ) {
2742                         $this->mTrxPreCommitCallbacks[] = [ $callback, wfGetCaller() ];
2743                 } else {
2744                         // If no transaction is active, then make one for this callback
2745                         $this->startAtomic( __METHOD__ );
2746                         try {
2747                                 call_user_func( $callback );
2748                                 $this->endAtomic( __METHOD__ );
2749                         } catch ( Exception $e ) {
2750                                 $this->rollback( __METHOD__, self::FLUSHING_INTERNAL );
2751                                 throw $e;
2752                         }
2753                 }
2754         }
2755
2756         final public function setTransactionListener( $name, callable $callback = null ) {
2757                 if ( $callback ) {
2758                         $this->mTrxRecurringCallbacks[$name] = [ $callback, wfGetCaller() ];
2759                 } else {
2760                         unset( $this->mTrxRecurringCallbacks[$name] );
2761                 }
2762         }
2763
2764         /**
2765          * Whether to disable running of post-COMMIT/ROLLBACK callbacks
2766          *
2767          * This method should not be used outside of Database/LoadBalancer
2768          *
2769          * @param bool $suppress
2770          * @since 1.28
2771          */
2772         final public function setTrxEndCallbackSuppression( $suppress ) {
2773                 $this->mTrxEndCallbacksSuppressed = $suppress;
2774         }
2775
2776         /**
2777          * Actually run and consume any "on transaction idle/resolution" callbacks.
2778          *
2779          * This method should not be used outside of Database/LoadBalancer
2780          *
2781          * @param integer $trigger IDatabase::TRIGGER_* constant
2782          * @since 1.20
2783          * @throws Exception
2784          */
2785         public function runOnTransactionIdleCallbacks( $trigger ) {
2786                 if ( $this->mTrxEndCallbacksSuppressed ) {
2787                         return;
2788                 }
2789
2790                 $autoTrx = $this->getFlag( DBO_TRX ); // automatic begin() enabled?
2791                 /** @var Exception $e */
2792                 $e = null; // first exception
2793                 do { // callbacks may add callbacks :)
2794                         $callbacks = array_merge(
2795                                 $this->mTrxIdleCallbacks,
2796                                 $this->mTrxEndCallbacks // include "transaction resolution" callbacks
2797                         );
2798                         $this->mTrxIdleCallbacks = []; // consumed (and recursion guard)
2799                         $this->mTrxEndCallbacks = []; // consumed (recursion guard)
2800                         foreach ( $callbacks as $callback ) {
2801                                 try {
2802                                         list( $phpCallback ) = $callback;
2803                                         $this->clearFlag( DBO_TRX ); // make each query its own transaction
2804                                         call_user_func_array( $phpCallback, [ $trigger ] );
2805                                         if ( $autoTrx ) {
2806                                                 $this->setFlag( DBO_TRX ); // restore automatic begin()
2807                                         } else {
2808                                                 $this->clearFlag( DBO_TRX ); // restore auto-commit
2809                                         }
2810                                 } catch ( Exception $ex ) {
2811                                         call_user_func( $this->errorLogger, $ex );
2812                                         $e = $e ?: $ex;
2813                                         // Some callbacks may use startAtomic/endAtomic, so make sure
2814                                         // their transactions are ended so other callbacks don't fail
2815                                         if ( $this->trxLevel() ) {
2816                                                 $this->rollback( __METHOD__, self::FLUSHING_INTERNAL );
2817                                         }
2818                                 }
2819                         }
2820                 } while ( count( $this->mTrxIdleCallbacks ) );
2821
2822                 if ( $e instanceof Exception ) {
2823                         throw $e; // re-throw any first exception
2824                 }
2825         }
2826
2827         /**
2828          * Actually run and consume any "on transaction pre-commit" callbacks.
2829          *
2830          * This method should not be used outside of Database/LoadBalancer
2831          *
2832          * @since 1.22
2833          * @throws Exception
2834          */
2835         public function runOnTransactionPreCommitCallbacks() {
2836                 $e = null; // first exception
2837                 do { // callbacks may add callbacks :)
2838                         $callbacks = $this->mTrxPreCommitCallbacks;
2839                         $this->mTrxPreCommitCallbacks = []; // consumed (and recursion guard)
2840                         foreach ( $callbacks as $callback ) {
2841                                 try {
2842                                         list( $phpCallback ) = $callback;
2843                                         call_user_func( $phpCallback );
2844                                 } catch ( Exception $ex ) {
2845                                         call_user_func( $this->errorLogger, $ex );
2846                                         $e = $e ?: $ex;
2847                                 }
2848                         }
2849                 } while ( count( $this->mTrxPreCommitCallbacks ) );
2850
2851                 if ( $e instanceof Exception ) {
2852                         throw $e; // re-throw any first exception
2853                 }
2854         }
2855
2856         /**
2857          * Actually run any "transaction listener" callbacks.
2858          *
2859          * This method should not be used outside of Database/LoadBalancer
2860          *
2861          * @param integer $trigger IDatabase::TRIGGER_* constant
2862          * @throws Exception
2863          * @since 1.20
2864          */
2865         public function runTransactionListenerCallbacks( $trigger ) {
2866                 if ( $this->mTrxEndCallbacksSuppressed ) {
2867                         return;
2868                 }
2869
2870                 /** @var Exception $e */
2871                 $e = null; // first exception
2872
2873                 foreach ( $this->mTrxRecurringCallbacks as $callback ) {
2874                         try {
2875                                 list( $phpCallback ) = $callback;
2876                                 $phpCallback( $trigger, $this );
2877                         } catch ( Exception $ex ) {
2878                                 call_user_func( $this->errorLogger, $ex );
2879                                 $e = $e ?: $ex;
2880                         }
2881                 }
2882
2883                 if ( $e instanceof Exception ) {
2884                         throw $e; // re-throw any first exception
2885                 }
2886         }
2887
2888         final public function startAtomic( $fname = __METHOD__ ) {
2889                 if ( !$this->mTrxLevel ) {
2890                         $this->begin( $fname, self::TRANSACTION_INTERNAL );
2891                         // If DBO_TRX is set, a series of startAtomic/endAtomic pairs will result
2892                         // in all changes being in one transaction to keep requests transactional.
2893                         if ( !$this->getFlag( DBO_TRX ) ) {
2894                                 $this->mTrxAutomaticAtomic = true;
2895                         }
2896                 }
2897
2898                 $this->mTrxAtomicLevels[] = $fname;
2899         }
2900
2901         final public function endAtomic( $fname = __METHOD__ ) {
2902                 if ( !$this->mTrxLevel ) {
2903                         throw new DBUnexpectedError( $this, "No atomic transaction is open (got $fname)." );
2904                 }
2905                 if ( !$this->mTrxAtomicLevels ||
2906                         array_pop( $this->mTrxAtomicLevels ) !== $fname
2907                 ) {
2908                         throw new DBUnexpectedError( $this, "Invalid atomic section ended (got $fname)." );
2909                 }
2910
2911                 if ( !$this->mTrxAtomicLevels && $this->mTrxAutomaticAtomic ) {
2912                         $this->commit( $fname, self::FLUSHING_INTERNAL );
2913                 }
2914         }
2915
2916         final public function doAtomicSection( $fname, callable $callback ) {
2917                 $this->startAtomic( $fname );
2918                 try {
2919                         $res = call_user_func_array( $callback, [ $this, $fname ] );
2920                 } catch ( Exception $e ) {
2921                         $this->rollback( $fname, self::FLUSHING_INTERNAL );
2922                         throw $e;
2923                 }
2924                 $this->endAtomic( $fname );
2925
2926                 return $res;
2927         }
2928
2929         final public function begin( $fname = __METHOD__, $mode = self::TRANSACTION_EXPLICIT ) {
2930                 // Protect against mismatched atomic section, transaction nesting, and snapshot loss
2931                 if ( $this->mTrxLevel ) {
2932                         if ( $this->mTrxAtomicLevels ) {
2933                                 $levels = implode( ', ', $this->mTrxAtomicLevels );
2934                                 $msg = "$fname: Got explicit BEGIN while atomic section(s) $levels are open.";
2935                                 throw new DBUnexpectedError( $this, $msg );
2936                         } elseif ( !$this->mTrxAutomatic ) {
2937                                 $msg = "$fname: Explicit transaction already active (from {$this->mTrxFname}).";
2938                                 throw new DBUnexpectedError( $this, $msg );
2939                         } else {
2940                                 // @TODO: make this an exception at some point
2941                                 $msg = "$fname: Implicit transaction already active (from {$this->mTrxFname}).";
2942                                 $this->queryLogger->error( $msg );
2943                                 return; // join the main transaction set
2944                         }
2945                 } elseif ( $this->getFlag( DBO_TRX ) && $mode !== self::TRANSACTION_INTERNAL ) {
2946                         // @TODO: make this an exception at some point
2947                         $msg = "$fname: Implicit transaction expected (DBO_TRX set).";
2948                         $this->queryLogger->error( $msg );
2949                         return; // let any writes be in the main transaction
2950                 }
2951
2952                 // Avoid fatals if close() was called
2953                 $this->assertOpen();
2954
2955                 $this->doBegin( $fname );
2956                 $this->mTrxTimestamp = microtime( true );
2957                 $this->mTrxFname = $fname;
2958                 $this->mTrxDoneWrites = false;
2959                 $this->mTrxAutomatic = ( $mode === self::TRANSACTION_INTERNAL );
2960                 $this->mTrxAutomaticAtomic = false;
2961                 $this->mTrxAtomicLevels = [];
2962                 $this->mTrxShortId = wfRandomString( 12 );
2963                 $this->mTrxWriteDuration = 0.0;
2964                 $this->mTrxWriteQueryCount = 0;
2965                 $this->mTrxWriteAdjDuration = 0.0;
2966                 $this->mTrxWriteAdjQueryCount = 0;
2967                 $this->mTrxWriteCallers = [];
2968                 // First SELECT after BEGIN will establish the snapshot in REPEATABLE-READ.
2969                 // Get an estimate of the replica DB lag before then, treating estimate staleness
2970                 // as lag itself just to be safe
2971                 $status = $this->getApproximateLagStatus();
2972                 $this->mTrxReplicaLag = $status['lag'] + ( microtime( true ) - $status['since'] );
2973         }
2974
2975         /**
2976          * Issues the BEGIN command to the database server.
2977          *
2978          * @see DatabaseBase::begin()
2979          * @param string $fname
2980          */
2981         protected function doBegin( $fname ) {
2982                 $this->query( 'BEGIN', $fname );
2983                 $this->mTrxLevel = 1;
2984         }
2985
2986         final public function commit( $fname = __METHOD__, $flush = '' ) {
2987                 if ( $this->mTrxLevel && $this->mTrxAtomicLevels ) {
2988                         // There are still atomic sections open. This cannot be ignored
2989                         $levels = implode( ', ', $this->mTrxAtomicLevels );
2990                         throw new DBUnexpectedError(
2991                                 $this,
2992                                 "$fname: Got COMMIT while atomic sections $levels are still open."
2993                         );
2994                 }
2995
2996                 if ( $flush === self::FLUSHING_INTERNAL || $flush === self::FLUSHING_ALL_PEERS ) {
2997                         if ( !$this->mTrxLevel ) {
2998                                 return; // nothing to do
2999                         } elseif ( !$this->mTrxAutomatic ) {
3000                                 throw new DBUnexpectedError(
3001                                         $this,
3002                                         "$fname: Flushing an explicit transaction, getting out of sync."
3003                                 );
3004                         }
3005                 } else {
3006                         if ( !$this->mTrxLevel ) {
3007                                 $this->queryLogger->error( "$fname: No transaction to commit, something got out of sync." );
3008                                 return; // nothing to do
3009                         } elseif ( $this->mTrxAutomatic ) {
3010                                 // @TODO: make this an exception at some point
3011                                 $msg = "$fname: Explicit commit of implicit transaction.";
3012                                 $this->queryLogger->error( $msg );
3013                                 return; // wait for the main transaction set commit round
3014                         }
3015                 }
3016
3017                 // Avoid fatals if close() was called
3018                 $this->assertOpen();
3019
3020                 $this->runOnTransactionPreCommitCallbacks();
3021                 $writeTime = $this->pendingWriteQueryDuration( self::ESTIMATE_DB_APPLY );
3022                 $this->doCommit( $fname );
3023                 if ( $this->mTrxDoneWrites ) {
3024                         $this->mDoneWrites = microtime( true );
3025                         $this->trxProfiler->transactionWritingOut(
3026                                 $this->mServer, $this->mDBname, $this->mTrxShortId, $writeTime );
3027                 }
3028
3029                 $this->runOnTransactionIdleCallbacks( self::TRIGGER_COMMIT );
3030                 $this->runTransactionListenerCallbacks( self::TRIGGER_COMMIT );
3031         }
3032
3033         /**
3034          * Issues the COMMIT command to the database server.
3035          *
3036          * @see DatabaseBase::commit()
3037          * @param string $fname
3038          */
3039         protected function doCommit( $fname ) {
3040                 if ( $this->mTrxLevel ) {
3041                         $this->query( 'COMMIT', $fname );
3042                         $this->mTrxLevel = 0;
3043                 }
3044         }
3045
3046         final public function rollback( $fname = __METHOD__, $flush = '' ) {
3047                 if ( $flush === self::FLUSHING_INTERNAL || $flush === self::FLUSHING_ALL_PEERS ) {
3048                         if ( !$this->mTrxLevel ) {
3049                                 return; // nothing to do
3050                         }
3051                 } else {
3052                         if ( !$this->mTrxLevel ) {
3053                                 $this->queryLogger->error(
3054                                         "$fname: No transaction to rollback, something got out of sync." );
3055                                 return; // nothing to do
3056                         } elseif ( $this->getFlag( DBO_TRX ) ) {
3057                                 throw new DBUnexpectedError(
3058                                         $this,
3059                                         "$fname: Expected mass rollback of all peer databases (DBO_TRX set)."
3060                                 );
3061                         }
3062                 }
3063
3064                 // Avoid fatals if close() was called
3065                 $this->assertOpen();
3066
3067                 $this->doRollback( $fname );
3068                 $this->mTrxAtomicLevels = [];
3069                 if ( $this->mTrxDoneWrites ) {
3070                         $this->trxProfiler->transactionWritingOut(
3071                                 $this->mServer, $this->mDBname, $this->mTrxShortId );
3072                 }
3073
3074                 $this->mTrxIdleCallbacks = []; // clear
3075                 $this->mTrxPreCommitCallbacks = []; // clear
3076                 $this->runOnTransactionIdleCallbacks( self::TRIGGER_ROLLBACK );
3077                 $this->runTransactionListenerCallbacks( self::TRIGGER_ROLLBACK );
3078         }
3079
3080         /**
3081          * Issues the ROLLBACK command to the database server.
3082          *
3083          * @see DatabaseBase::rollback()
3084          * @param string $fname
3085          */
3086         protected function doRollback( $fname ) {
3087                 if ( $this->mTrxLevel ) {
3088                         # Disconnects cause rollback anyway, so ignore those errors
3089                         $ignoreErrors = true;
3090                         $this->query( 'ROLLBACK', $fname, $ignoreErrors );
3091                         $this->mTrxLevel = 0;
3092                 }
3093         }
3094
3095         public function flushSnapshot( $fname = __METHOD__ ) {
3096                 if ( $this->writesOrCallbacksPending() || $this->explicitTrxActive() ) {
3097                         // This only flushes transactions to clear snapshots, not to write data
3098                         throw new DBUnexpectedError(
3099                                 $this,
3100                                 "$fname: Cannot COMMIT to clear snapshot because writes are pending."
3101                         );
3102                 }
3103
3104                 $this->commit( $fname, self::FLUSHING_INTERNAL );
3105         }
3106
3107         public function explicitTrxActive() {
3108                 return $this->mTrxLevel && ( $this->mTrxAtomicLevels || !$this->mTrxAutomatic );
3109         }
3110
3111         /**
3112          * Creates a new table with structure copied from existing table
3113          * Note that unlike most database abstraction functions, this function does not
3114          * automatically append database prefix, because it works at a lower
3115          * abstraction level.
3116          * The table names passed to this function shall not be quoted (this
3117          * function calls addIdentifierQuotes when needed).
3118          *
3119          * @param string $oldName Name of table whose structure should be copied
3120          * @param string $newName Name of table to be created
3121          * @param bool $temporary Whether the new table should be temporary
3122          * @param string $fname Calling function name
3123          * @throws RuntimeException
3124          * @return bool True if operation was successful
3125          */
3126         public function duplicateTableStructure( $oldName, $newName, $temporary = false,
3127                 $fname = __METHOD__
3128         ) {
3129                 throw new RuntimeException( __METHOD__ . ' is not implemented in descendant class' );
3130         }
3131
3132         function listTables( $prefix = null, $fname = __METHOD__ ) {
3133                 throw new RuntimeException( __METHOD__ . ' is not implemented in descendant class' );
3134         }
3135
3136         /**
3137          * Reset the views process cache set by listViews()
3138          * @since 1.22
3139          */
3140         final public function clearViewsCache() {
3141                 $this->allViews = null;
3142         }
3143
3144         /**
3145          * Lists all the VIEWs in the database
3146          *
3147          * For caching purposes the list of all views should be stored in
3148          * $this->allViews. The process cache can be cleared with clearViewsCache()
3149          *
3150          * @param string $prefix Only show VIEWs with this prefix, eg. unit_test_
3151          * @param string $fname Name of calling function
3152          * @throws RuntimeException
3153          * @return array
3154          * @since 1.22
3155          */
3156         public function listViews( $prefix = null, $fname = __METHOD__ ) {
3157                 throw new RuntimeException( __METHOD__ . ' is not implemented in descendant class' );
3158         }
3159
3160         /**
3161          * Differentiates between a TABLE and a VIEW
3162          *
3163          * @param string $name Name of the database-structure to test.
3164          * @throws RuntimeException
3165          * @return bool
3166          * @since 1.22
3167          */
3168         public function isView( $name ) {
3169                 throw new RuntimeException( __METHOD__ . ' is not implemented in descendant class' );
3170         }
3171
3172         public function timestamp( $ts = 0 ) {
3173                 return wfTimestamp( TS_MW, $ts );
3174         }
3175
3176         public function timestampOrNull( $ts = null ) {
3177                 if ( is_null( $ts ) ) {
3178                         return null;
3179                 } else {
3180                         return $this->timestamp( $ts );
3181                 }
3182         }
3183
3184         /**
3185          * Take the result from a query, and wrap it in a ResultWrapper if
3186          * necessary. Boolean values are passed through as is, to indicate success
3187          * of write queries or failure.
3188          *
3189          * Once upon a time, DatabaseBase::query() returned a bare MySQL result
3190          * resource, and it was necessary to call this function to convert it to
3191          * a wrapper. Nowadays, raw database objects are never exposed to external
3192          * callers, so this is unnecessary in external code.
3193          *
3194          * @param bool|ResultWrapper|resource|object $result
3195          * @return bool|ResultWrapper
3196          */
3197         protected function resultObject( $result ) {
3198                 if ( !$result ) {
3199                         return false;
3200                 } elseif ( $result instanceof ResultWrapper ) {
3201                         return $result;
3202                 } elseif ( $result === true ) {
3203                         // Successful write query
3204                         return $result;
3205                 } else {
3206                         return new ResultWrapper( $this, $result );
3207                 }
3208         }
3209
3210         public function ping( &$rtt = null ) {
3211                 // Avoid hitting the server if it was hit recently
3212                 if ( $this->isOpen() && ( microtime( true ) - $this->lastPing ) < self::PING_TTL ) {
3213                         if ( !func_num_args() || $this->mRTTEstimate > 0 ) {
3214                                 $rtt = $this->mRTTEstimate;
3215                                 return true; // don't care about $rtt
3216                         }
3217                 }
3218
3219                 // This will reconnect if possible or return false if not
3220                 $this->clearFlag( DBO_TRX, self::REMEMBER_PRIOR );
3221                 $ok = ( $this->query( self::PING_QUERY, __METHOD__, true ) !== false );
3222                 $this->restoreFlags( self::RESTORE_PRIOR );
3223
3224                 if ( $ok ) {
3225                         $rtt = $this->mRTTEstimate;
3226                 }
3227
3228                 return $ok;
3229         }
3230
3231         /**
3232          * @return bool
3233          */
3234         protected function reconnect() {
3235                 $this->closeConnection();
3236                 $this->mOpened = false;
3237                 $this->mConn = false;
3238                 try {
3239                         $this->open( $this->mServer, $this->mUser, $this->mPassword, $this->mDBname );
3240                         $this->lastPing = microtime( true );
3241                         $ok = true;
3242                 } catch ( DBConnectionError $e ) {
3243                         $ok = false;
3244                 }
3245
3246                 return $ok;
3247         }
3248
3249         public function getSessionLagStatus() {
3250                 return $this->getTransactionLagStatus() ?: $this->getApproximateLagStatus();
3251         }
3252
3253         /**
3254          * Get the replica DB lag when the current transaction started
3255          *
3256          * This is useful when transactions might use snapshot isolation
3257          * (e.g. REPEATABLE-READ in innodb), so the "real" lag of that data
3258          * is this lag plus transaction duration. If they don't, it is still
3259          * safe to be pessimistic. This returns null if there is no transaction.
3260          *
3261          * @return array|null ('lag': seconds or false on error, 'since': UNIX timestamp of BEGIN)
3262          * @since 1.27
3263          */
3264         public function getTransactionLagStatus() {
3265                 return $this->mTrxLevel
3266                         ? [ 'lag' => $this->mTrxReplicaLag, 'since' => $this->trxTimestamp() ]
3267                         : null;
3268         }
3269
3270         /**
3271          * Get a replica DB lag estimate for this server
3272          *
3273          * @return array ('lag': seconds or false on error, 'since': UNIX timestamp of estimate)
3274          * @since 1.27
3275          */
3276         public function getApproximateLagStatus() {
3277                 return [
3278                         'lag'   => $this->getLBInfo( 'replica' ) ? $this->getLag() : 0,
3279                         'since' => microtime( true )
3280                 ];
3281         }
3282
3283         /**
3284          * Merge the result of getSessionLagStatus() for several DBs
3285          * using the most pessimistic values to estimate the lag of
3286          * any data derived from them in combination
3287          *
3288          * This is information is useful for caching modules
3289          *
3290          * @see WANObjectCache::set()
3291          * @see WANObjectCache::getWithSetCallback()
3292          *
3293          * @param IDatabase $db1
3294          * @param IDatabase ...
3295          * @return array Map of values:
3296          *   - lag: highest lag of any of the DBs or false on error (e.g. replication stopped)
3297          *   - since: oldest UNIX timestamp of any of the DB lag estimates
3298          *   - pending: whether any of the DBs have uncommitted changes
3299          * @since 1.27
3300          */
3301         public static function getCacheSetOptions( IDatabase $db1 ) {
3302                 $res = [ 'lag' => 0, 'since' => INF, 'pending' => false ];
3303                 foreach ( func_get_args() as $db ) {
3304                         /** @var IDatabase $db */
3305                         $status = $db->getSessionLagStatus();
3306                         if ( $status['lag'] === false ) {
3307                                 $res['lag'] = false;
3308                         } elseif ( $res['lag'] !== false ) {
3309                                 $res['lag'] = max( $res['lag'], $status['lag'] );
3310                         }
3311                         $res['since'] = min( $res['since'], $status['since'] );
3312                         $res['pending'] = $res['pending'] ?: $db->writesPending();
3313                 }
3314
3315                 return $res;
3316         }
3317
3318         public function getLag() {
3319                 return 0;
3320         }
3321
3322         function maxListLen() {
3323                 return 0;
3324         }
3325
3326         public function encodeBlob( $b ) {
3327                 return $b;
3328         }
3329
3330         public function decodeBlob( $b ) {
3331                 if ( $b instanceof Blob ) {
3332                         $b = $b->fetch();
3333                 }
3334                 return $b;
3335         }
3336
3337         public function setSessionOptions( array $options ) {
3338         }
3339
3340         /**
3341          * Read and execute SQL commands from a file.
3342          *
3343          * Returns true on success, error string or exception on failure (depending
3344          * on object's error ignore settings).
3345          *
3346          * @param string $filename File name to open
3347          * @param bool|callable $lineCallback Optional function called before reading each line
3348          * @param bool|callable $resultCallback Optional function called for each MySQL result
3349          * @param bool|string $fname Calling function name or false if name should be
3350          *   generated dynamically using $filename
3351          * @param bool|callable $inputCallback Optional function called for each
3352          *   complete line sent
3353          * @return bool|string
3354          * @throws Exception
3355          */
3356         public function sourceFile(
3357                 $filename, $lineCallback = false, $resultCallback = false, $fname = false, $inputCallback = false
3358         ) {
3359                 MediaWiki\suppressWarnings();
3360                 $fp = fopen( $filename, 'r' );
3361                 MediaWiki\restoreWarnings();
3362
3363                 if ( false === $fp ) {
3364                         throw new RuntimeException( "Could not open \"{$filename}\".\n" );
3365                 }
3366
3367                 if ( !$fname ) {
3368                         $fname = __METHOD__ . "( $filename )";
3369                 }
3370
3371                 try {
3372                         $error = $this->sourceStream( $fp, $lineCallback, $resultCallback, $fname, $inputCallback );
3373                 } catch ( Exception $e ) {
3374                         fclose( $fp );
3375                         throw $e;
3376                 }
3377
3378                 fclose( $fp );
3379
3380                 return $error;
3381         }
3382
3383         /**
3384          * Get the full path of a patch file. Originally based on archive()
3385          * from updaters.inc. Keep in mind this always returns a patch, as
3386          * it fails back to MySQL if no DB-specific patch can be found
3387          *
3388          * @param string $patch The name of the patch, like patch-something.sql
3389          * @return string Full path to patch file
3390          */
3391         public function patchPath( $patch ) {
3392                 global $IP;
3393
3394                 $dbType = $this->getType();
3395                 if ( file_exists( "$IP/maintenance/$dbType/archives/$patch" ) ) {
3396                         return "$IP/maintenance/$dbType/archives/$patch";
3397                 } else {
3398                         return "$IP/maintenance/archives/$patch";
3399                 }
3400         }
3401
3402         public function setSchemaVars( $vars ) {
3403                 $this->mSchemaVars = $vars;
3404         }
3405
3406         /**
3407          * Read and execute commands from an open file handle.
3408          *
3409          * Returns true on success, error string or exception on failure (depending
3410          * on object's error ignore settings).
3411          *
3412          * @param resource $fp File handle
3413          * @param bool|callable $lineCallback Optional function called before reading each query
3414          * @param bool|callable $resultCallback Optional function called for each MySQL result
3415          * @param string $fname Calling function name
3416          * @param bool|callable $inputCallback Optional function called for each complete query sent
3417          * @return bool|string
3418          */
3419         public function sourceStream( $fp, $lineCallback = false, $resultCallback = false,
3420                 $fname = __METHOD__, $inputCallback = false
3421         ) {
3422                 $cmd = '';
3423
3424                 while ( !feof( $fp ) ) {
3425                         if ( $lineCallback ) {
3426                                 call_user_func( $lineCallback );
3427                         }
3428
3429                         $line = trim( fgets( $fp ) );
3430
3431                         if ( $line == '' ) {
3432                                 continue;
3433                         }
3434
3435                         if ( '-' == $line[0] && '-' == $line[1] ) {
3436                                 continue;
3437                         }
3438
3439                         if ( $cmd != '' ) {
3440                                 $cmd .= ' ';
3441                         }
3442
3443                         $done = $this->streamStatementEnd( $cmd, $line );
3444
3445                         $cmd .= "$line\n";
3446
3447                         if ( $done || feof( $fp ) ) {
3448                                 $cmd = $this->replaceVars( $cmd );
3449
3450                                 if ( ( $inputCallback && call_user_func( $inputCallback, $cmd ) ) || !$inputCallback ) {
3451                                         $res = $this->query( $cmd, $fname );
3452
3453                                         if ( $resultCallback ) {
3454                                                 call_user_func( $resultCallback, $res, $this );
3455                                         }
3456
3457                                         if ( false === $res ) {
3458                                                 $err = $this->lastError();
3459
3460                                                 return "Query \"{$cmd}\" failed with error code \"$err\".\n";
3461                                         }
3462                                 }
3463                                 $cmd = '';
3464                         }
3465                 }
3466
3467                 return true;
3468         }
3469
3470         /**
3471          * Called by sourceStream() to check if we've reached a statement end
3472          *
3473          * @param string $sql SQL assembled so far
3474          * @param string $newLine New line about to be added to $sql
3475          * @return bool Whether $newLine contains end of the statement
3476          */
3477         public function streamStatementEnd( &$sql, &$newLine ) {
3478                 if ( $this->delimiter ) {
3479                         $prev = $newLine;
3480                         $newLine = preg_replace( '/' . preg_quote( $this->delimiter, '/' ) . '$/', '', $newLine );
3481                         if ( $newLine != $prev ) {
3482                                 return true;
3483                         }
3484                 }
3485
3486                 return false;
3487         }
3488
3489         /**
3490          * Database independent variable replacement. Replaces a set of variables
3491          * in an SQL statement with their contents as given by $this->getSchemaVars().
3492          *
3493          * Supports '{$var}' `{$var}` and / *$var* / (without the spaces) style variables.
3494          *
3495          * - '{$var}' should be used for text and is passed through the database's
3496          *   addQuotes method.
3497          * - `{$var}` should be used for identifiers (e.g. table and database names).
3498          *   It is passed through the database's addIdentifierQuotes method which
3499          *   can be overridden if the database uses something other than backticks.
3500          * - / *_* / or / *$wgDBprefix* / passes the name that follows through the
3501          *   database's tableName method.
3502          * - / *i* / passes the name that follows through the database's indexName method.
3503          * - In all other cases, / *$var* / is left unencoded. Except for table options,
3504          *   its use should be avoided. In 1.24 and older, string encoding was applied.
3505          *
3506          * @param string $ins SQL statement to replace variables in
3507          * @return string The new SQL statement with variables replaced
3508          */
3509         protected function replaceVars( $ins ) {
3510                 $vars = $this->getSchemaVars();
3511                 return preg_replace_callback(
3512                         '!
3513                                 /\* (\$wgDBprefix|[_i]) \*/ (\w*) | # 1-2. tableName, indexName
3514                                 \'\{\$ (\w+) }\'                  | # 3. addQuotes
3515                                 `\{\$ (\w+) }`                    | # 4. addIdentifierQuotes
3516                                 /\*\$ (\w+) \*/                     # 5. leave unencoded
3517                         !x',
3518                         function ( $m ) use ( $vars ) {
3519                                 // Note: Because of <https://bugs.php.net/bug.php?id=51881>,
3520                                 // check for both nonexistent keys *and* the empty string.
3521                                 if ( isset( $m[1] ) && $m[1] !== '' ) {
3522                                         if ( $m[1] === 'i' ) {
3523                                                 return $this->indexName( $m[2] );
3524                                         } else {
3525                                                 return $this->tableName( $m[2] );
3526                                         }
3527                                 } elseif ( isset( $m[3] ) && $m[3] !== '' && array_key_exists( $m[3], $vars ) ) {
3528                                         return $this->addQuotes( $vars[$m[3]] );
3529                                 } elseif ( isset( $m[4] ) && $m[4] !== '' && array_key_exists( $m[4], $vars ) ) {
3530                                         return $this->addIdentifierQuotes( $vars[$m[4]] );
3531                                 } elseif ( isset( $m[5] ) && $m[5] !== '' && array_key_exists( $m[5], $vars ) ) {
3532                                         return $vars[$m[5]];
3533                                 } else {
3534                                         return $m[0];
3535                                 }
3536                         },
3537                         $ins
3538                 );
3539         }
3540
3541         /**
3542          * Get schema variables. If none have been set via setSchemaVars(), then
3543          * use some defaults from the current object.
3544          *
3545          * @return array
3546          */
3547         protected function getSchemaVars() {
3548                 if ( $this->mSchemaVars ) {
3549                         return $this->mSchemaVars;
3550                 } else {
3551                         return $this->getDefaultSchemaVars();
3552                 }
3553         }
3554
3555         /**
3556          * Get schema variables to use if none have been set via setSchemaVars().
3557          *
3558          * Override this in derived classes to provide variables for tables.sql
3559          * and SQL patch files.
3560          *
3561          * @return array
3562          */
3563         protected function getDefaultSchemaVars() {
3564                 return [];
3565         }
3566
3567         public function lockIsFree( $lockName, $method ) {
3568                 return true;
3569         }
3570
3571         public function lock( $lockName, $method, $timeout = 5 ) {
3572                 $this->mNamedLocksHeld[$lockName] = 1;
3573
3574                 return true;
3575         }
3576
3577         public function unlock( $lockName, $method ) {
3578                 unset( $this->mNamedLocksHeld[$lockName] );
3579
3580                 return true;
3581         }
3582
3583         public function getScopedLockAndFlush( $lockKey, $fname, $timeout ) {
3584                 if ( $this->writesOrCallbacksPending() ) {
3585                         // This only flushes transactions to clear snapshots, not to write data
3586                         throw new DBUnexpectedError(
3587                                 $this,
3588                                 "$fname: Cannot COMMIT to clear snapshot because writes are pending."
3589                         );
3590                 }
3591
3592                 if ( !$this->lock( $lockKey, $fname, $timeout ) ) {
3593                         return null;
3594                 }
3595
3596                 $unlocker = new ScopedCallback( function () use ( $lockKey, $fname ) {
3597                         if ( $this->trxLevel() ) {
3598                                 // There is a good chance an exception was thrown, causing any early return
3599                                 // from the caller. Let any error handler get a chance to issue rollback().
3600                                 // If there isn't one, let the error bubble up and trigger server-side rollback.
3601                                 $this->onTransactionResolution( function () use ( $lockKey, $fname ) {
3602                                         $this->unlock( $lockKey, $fname );
3603                                 } );
3604                         } else {
3605                                 $this->unlock( $lockKey, $fname );
3606                         }
3607                 } );
3608
3609                 $this->commit( __METHOD__, self::FLUSHING_INTERNAL );
3610
3611                 return $unlocker;
3612         }
3613
3614         public function namedLocksEnqueue() {
3615                 return false;
3616         }
3617
3618         /**
3619          * Lock specific tables
3620          *
3621          * @param array $read Array of tables to lock for read access
3622          * @param array $write Array of tables to lock for write access
3623          * @param string $method Name of caller
3624          * @param bool $lowPriority Whether to indicate writes to be LOW PRIORITY
3625          * @return bool
3626          */
3627         public function lockTables( $read, $write, $method, $lowPriority = true ) {
3628                 return true;
3629         }
3630
3631         /**
3632          * Unlock specific tables
3633          *
3634          * @param string $method The caller
3635          * @return bool
3636          */
3637         public function unlockTables( $method ) {
3638                 return true;
3639         }
3640
3641         /**
3642          * Delete a table
3643          * @param string $tableName
3644          * @param string $fName
3645          * @return bool|ResultWrapper
3646          * @since 1.18
3647          */
3648         public function dropTable( $tableName, $fName = __METHOD__ ) {
3649                 if ( !$this->tableExists( $tableName, $fName ) ) {
3650                         return false;
3651                 }
3652                 $sql = "DROP TABLE " . $this->tableName( $tableName );
3653                 if ( $this->cascadingDeletes() ) {
3654                         $sql .= " CASCADE";
3655                 }
3656
3657                 return $this->query( $sql, $fName );
3658         }
3659
3660         /**
3661          * Get search engine class. All subclasses of this need to implement this
3662          * if they wish to use searching.
3663          *
3664          * @return string
3665          */
3666         public function getSearchEngine() {
3667                 return 'SearchEngineDummy';
3668         }
3669
3670         public function getInfinity() {
3671                 return 'infinity';
3672         }
3673
3674         public function encodeExpiry( $expiry ) {
3675                 return ( $expiry == '' || $expiry == 'infinity' || $expiry == $this->getInfinity() )
3676                         ? $this->getInfinity()
3677                         : $this->timestamp( $expiry );
3678         }
3679
3680         public function decodeExpiry( $expiry, $format = TS_MW ) {
3681                 return ( $expiry == '' || $expiry == 'infinity' || $expiry == $this->getInfinity() )
3682                         ? 'infinity'
3683                         : wfTimestamp( $format, $expiry );
3684         }
3685
3686         public function setBigSelects( $value = true ) {
3687                 // no-op
3688         }
3689
3690         public function isReadOnly() {
3691                 return ( $this->getReadOnlyReason() !== false );
3692         }
3693
3694         /**
3695          * @return string|bool Reason this DB is read-only or false if it is not
3696          */
3697         protected function getReadOnlyReason() {
3698                 $reason = $this->getLBInfo( 'readOnlyReason' );
3699
3700                 return is_string( $reason ) ? $reason : false;
3701         }
3702
3703         /**
3704          * @since 1.19
3705          * @return string
3706          */
3707         public function __toString() {
3708                 return (string)$this->mConn;
3709         }
3710
3711         /**
3712          * Run a few simple sanity checks
3713          */
3714         public function __destruct() {
3715                 if ( $this->mTrxLevel && $this->mTrxDoneWrites ) {
3716                         trigger_error( "Uncommitted DB writes (transaction from {$this->mTrxFname})." );
3717                 }
3718                 $danglingCallbacks = array_merge(
3719                         $this->mTrxIdleCallbacks,
3720                         $this->mTrxPreCommitCallbacks,
3721                         $this->mTrxEndCallbacks
3722                 );
3723                 if ( $danglingCallbacks ) {
3724                         $callers = [];
3725                         foreach ( $danglingCallbacks as $callbackInfo ) {
3726                                 $callers[] = $callbackInfo[1];
3727                         }
3728                         $callers = implode( ', ', $callers );
3729                         trigger_error( "DB transaction callbacks still pending (from $callers)." );
3730                 }
3731         }
3732 }
3733
3734 /**
3735  * @since 1.27
3736  */
3737 abstract class Database extends DatabaseBase {
3738         // B/C until nothing type hints for DatabaseBase
3739         // @TODO: finish renaming DatabaseBase => Database
3740 }