includes/db/Database.php

   1 <?php
   2 /**
   3  * @defgroup Database Database
   4  *
   5  * This file deals with database interface functions
   6  * and query specifics/optimisations.
   7  *
   8  * This program is free software; you can redistribute it and/or modify
   9  * it under the terms of the GNU General Public License as published by
  10  * the Free Software Foundation; either version 2 of the License, or
  11  * (at your option) any later version.
  12  *
  13  * This program is distributed in the hope that it will be useful,
  14  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  15  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
  16  * GNU General Public License for more details.
  17  *
  18  * You should have received a copy of the GNU General Public License along
  19  * with this program; if not, write to the Free Software Foundation, Inc.,
  20  * 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
  21  * http://www.gnu.org/copyleft/gpl.html
  22  *
  23  * @file
  24  * @ingroup Database
  25  */
  26 use Psr\Log\LoggerAwareInterface;
  27 use Psr\Log\LoggerInterface;
  28
  29 /**
  30  * Database abstraction object
  31  * @ingroup Database
  32  */
  33 abstract class DatabaseBase implements IDatabase, LoggerAwareInterface {
  34         /** Number of times to re-try an operation in case of deadlock */
  35         const DEADLOCK_TRIES = 4;
  36         /** Minimum time to wait before retry, in microseconds */
  37         const DEADLOCK_DELAY_MIN = 500000;
  38         /** Maximum time to wait before retry */
  39         const DEADLOCK_DELAY_MAX = 1500000;
  40
  41         /** How long before it is worth doing a dummy query to test the connection */
  42         const PING_TTL = 1.0;
  43         const PING_QUERY = 'SELECT 1 AS ping';
  44
  45         const TINY_WRITE_SEC = .010;
  46         const SLOW_WRITE_SEC = .500;
  47         const SMALL_WRITE_ROWS = 100;
  48
  49         /** @var string SQL query */
  50         protected $mLastQuery = '';
  51         /** @var bool */
  52         protected $mDoneWrites = false;
  53         /** @var string|bool */
  54         protected $mPHPError = false;
  55         /** @var string */
  56         protected $mServer;
  57         /** @var string */
  58         protected $mUser;
  59         /** @var string */
  60         protected $mPassword;
  61         /** @var string */
  62         protected $mDBname;
  63         /** @var array[] $aliases Map of (table => (dbname, schema, prefix) map) */
  64         protected $tableAliases = [];
  65         /** @var bool */
  66         protected $cliMode;
  67
  68         /** @var BagOStuff APC cache */
  69         protected $srvCache;
  70         /** @var LoggerInterface */
  71         protected $connLogger;
  72         /** @var LoggerInterface */
  73         protected $queryLogger;
  74         /** @var callback Error logging callback */
  75         protected $errorLogger;
  76
  77         /** @var resource Database connection */
  78         protected $mConn = null;
  79         /** @var bool */
  80         protected $mOpened = false;
  81
  82         /** @var array[] List of (callable, method name) */
  83         protected $mTrxIdleCallbacks = [];
  84         /** @var array[] List of (callable, method name) */
  85         protected $mTrxPreCommitCallbacks = [];
  86         /** @var array[] List of (callable, method name) */
  87         protected $mTrxEndCallbacks = [];
  88         /** @var callable[] Map of (name => callable) */
  89         protected $mTrxRecurringCallbacks = [];
  90         /** @var bool Whether to suppress triggering of transaction end callbacks */
  91         protected $mTrxEndCallbacksSuppressed = false;
  92
  93         /** @var string */
  94         protected $mTablePrefix;
  95         /** @var string */
  96         protected $mSchema;
  97         /** @var integer */
  98         protected $mFlags;
  99         /** @var array */
 100         protected $mLBInfo = [];
 101         /** @var bool|null */
 102         protected $mDefaultBigSelects = null;
 103         /** @var array|bool */
 104         protected $mSchemaVars = false;
 105         /** @var array */
 106         protected $mSessionVars = [];
 107         /** @var array|null */
 108         protected $preparedArgs;
 109         /** @var string|bool|null Stashed value of html_errors INI setting */
 110         protected $htmlErrors;
 111         /** @var string */
 112         protected $delimiter = ';';
 113
 114         /**
 115          * Either 1 if a transaction is active or 0 otherwise.
 116          * The other Trx fields may not be meaningfull if this is 0.
 117          *
 118          * @var int
 119          */
 120         protected $mTrxLevel = 0;
 121         /**
 122          * Either a short hexidecimal string if a transaction is active or ""
 123          *
 124          * @var string
 125          * @see DatabaseBase::mTrxLevel
 126          */
 127         protected $mTrxShortId = '';
 128         /**
 129          * The UNIX time that the transaction started. Callers can assume that if
 130          * snapshot isolation is used, then the data is *at least* up to date to that
 131          * point (possibly more up-to-date since the first SELECT defines the snapshot).
 132          *
 133          * @var float|null
 134          * @see DatabaseBase::mTrxLevel
 135          */
 136         private $mTrxTimestamp = null;
 137         /** @var float Lag estimate at the time of BEGIN */
 138         private $mTrxReplicaLag = null;
 139         /**
 140          * Remembers the function name given for starting the most recent transaction via begin().
 141          * Used to provide additional context for error reporting.
 142          *
 143          * @var string
 144          * @see DatabaseBase::mTrxLevel
 145          */
 146         private $mTrxFname = null;
 147         /**
 148          * Record if possible write queries were done in the last transaction started
 149          *
 150          * @var bool
 151          * @see DatabaseBase::mTrxLevel
 152          */
 153         private $mTrxDoneWrites = false;
 154         /**
 155          * Record if the current transaction was started implicitly due to DBO_TRX being set.
 156          *
 157          * @var bool
 158          * @see DatabaseBase::mTrxLevel
 159          */
 160         private $mTrxAutomatic = false;
 161         /**
 162          * Array of levels of atomicity within transactions
 163          *
 164          * @var array
 165          */
 166         private $mTrxAtomicLevels = [];
 167         /**
 168          * Record if the current transaction was started implicitly by DatabaseBase::startAtomic
 169          *
 170          * @var bool
 171          */
 172         private $mTrxAutomaticAtomic = false;
 173         /**
 174          * Track the write query callers of the current transaction
 175          *
 176          * @var string[]
 177          */
 178         private $mTrxWriteCallers = [];
 179         /**
 180          * @var float Seconds spent in write queries for the current transaction
 181          */
 182         private $mTrxWriteDuration = 0.0;
 183         /**
 184          * @var integer Number of write queries for the current transaction
 185          */
 186         private $mTrxWriteQueryCount = 0;
 187         /**
 188          * @var float Like mTrxWriteQueryCount but excludes lock-bound, easy to replicate, queries
 189          */
 190         private $mTrxWriteAdjDuration = 0.0;
 191         /**
 192          * @var integer Number of write queries counted in mTrxWriteAdjDuration
 193          */
 194         private $mTrxWriteAdjQueryCount = 0;
 195         /**
 196          * @var float RTT time estimate
 197          */
 198         private $mRTTEstimate = 0.0;
 199
 200         /** @var array Map of (name => 1) for locks obtained via lock() */
 201         private $mNamedLocksHeld = [];
 202
 203         /** @var IDatabase|null Lazy handle to the master DB this server replicates from */
 204         private $lazyMasterHandle;
 205
 206         /**
 207          * @since 1.21
 208          * @var resource File handle for upgrade
 209          */
 210         protected $fileHandle = null;
 211
 212         /**
 213          * @since 1.22
 214          * @var string[] Process cache of VIEWs names in the database
 215          */
 216         protected $allViews = null;
 217
 218         /** @var float UNIX timestamp */
 219         protected $lastPing = 0.0;
 220
 221         /** @var int[] Prior mFlags values */
 222         private $priorFlags = [];
 223
 224         /** @var Profiler */
 225         protected $profiler;
 226         /** @var TransactionProfiler */
 227         protected $trxProfiler;
 228
 229         /**
 230          * Constructor.
 231          *
 232          * FIXME: It is possible to construct a Database object with no associated
 233          * connection object, by specifying no parameters to __construct(). This
 234          * feature is deprecated and should be removed.
 235          *
 236          * IDatabase classes should not be constructed directly in external
 237          * code. DatabaseBase::factory() should be used instead.
 238          *
 239          * @param array $params Parameters passed from DatabaseBase::factory()
 240          */
 241         function __construct( array $params ) {
 242                 $server = $params['host'];
 243                 $user = $params['user'];
 244                 $password = $params['password'];
 245                 $dbName = $params['dbname'];
 246                 $flags = $params['flags'];
 247
 248                 $this->mSchema = $params['schema'];
 249                 $this->mTablePrefix = $params['tablePrefix'];
 250
 251                 $this->cliMode = isset( $params['cliMode'] )
 252                         ? $params['cliMode']
 253                         : ( PHP_SAPI === 'cli' );
 254
 255                 $this->mFlags = $flags;
 256                 if ( $this->mFlags & DBO_DEFAULT ) {
 257                         if ( $this->cliMode ) {
 258                                 $this->mFlags &= ~DBO_TRX;
 259                         } else {
 260                                 $this->mFlags |= DBO_TRX;
 261                         }
 262                 }
 263
 264                 $this->mSessionVars = $params['variables'];
 265
 266                 $this->srvCache = isset( $params['srvCache'] )
 267                         ? $params['srvCache']
 268                         : new HashBagOStuff();
 269
 270                 $this->profiler = isset( $params['profiler'] )
 271                         ? $params['profiler']
 272                         : Profiler::instance(); // @TODO: remove global state
 273                 $this->trxProfiler = isset( $params['trxProfiler'] )
 274                         ? $params['trxProfiler']
 275                         : new TransactionProfiler();
 276                 $this->connLogger = isset( $params['connLogger'] )
 277                         ? $params['connLogger']
 278                         : new \Psr\Log\NullLogger();
 279                 $this->queryLogger = isset( $params['queryLogger'] )
 280                         ? $params['queryLogger']
 281                         : new \Psr\Log\NullLogger();
 282
 283                 if ( $user ) {
 284                         $this->open( $server, $user, $password, $dbName );
 285                 }
 286         }
 287
 288         /**
 289          * Given a DB type, construct the name of the appropriate child class of
 290          * IDatabase. This is designed to replace all of the manual stuff like:
 291          *    $class = 'Database' . ucfirst( strtolower( $dbType ) );
 292          * as well as validate against the canonical list of DB types we have
 293          *
 294          * This factory function is mostly useful for when you need to connect to a
 295          * database other than the MediaWiki default (such as for external auth,
 296          * an extension, et cetera). Do not use this to connect to the MediaWiki
 297          * database. Example uses in core:
 298          * @see LoadBalancer::reallyOpenConnection()
 299          * @see ForeignDBRepo::getMasterDB()
 300          * @see WebInstallerDBConnect::execute()
 301          *
 302          * @since 1.18
 303          *
 304          * @param string $dbType A possible DB type
 305          * @param array $p An array of options to pass to the constructor.
 306          *    Valid options are: host, user, password, dbname, flags, tablePrefix, schema, driver
 307          * @return IDatabase|null If the database driver or extension cannot be found
 308          * @throws InvalidArgumentException If the database driver or extension cannot be found
 309          */
 310         final public static function factory( $dbType, $p = [] ) {
 311                 global $wgCommandLineMode;
 312
 313                 $canonicalDBTypes = [
 314                         'mysql' => [ 'mysqli', 'mysql' ],
 315                         'postgres' => [],
 316                         'sqlite' => [],
 317                         'oracle' => [],
 318                         'mssql' => [],
 319                 ];
 320
 321                 $driver = false;
 322                 $dbType = strtolower( $dbType );
 323                 if ( isset( $canonicalDBTypes[$dbType] ) && $canonicalDBTypes[$dbType] ) {
 324                         $possibleDrivers = $canonicalDBTypes[$dbType];
 325                         if ( !empty( $p['driver'] ) ) {
 326                                 if ( in_array( $p['driver'], $possibleDrivers ) ) {
 327                                         $driver = $p['driver'];
 328                                 } else {
 329                                         throw new InvalidArgumentException( __METHOD__ .
 330                                                 " type '$dbType' does not support driver '{$p['driver']}'" );
 331                                 }
 332                         } else {
 333                                 foreach ( $possibleDrivers as $posDriver ) {
 334                                         if ( extension_loaded( $posDriver ) ) {
 335                                                 $driver = $posDriver;
 336                                                 break;
 337                                         }
 338                                 }
 339                         }
 340                 } else {
 341                         $driver = $dbType;
 342                 }
 343                 if ( $driver === false ) {
 344                         throw new InvalidArgumentException( __METHOD__ .
 345                                 " no viable database extension found for type '$dbType'" );
 346                 }
 347
 348                 // Determine schema defaults. Currently Microsoft SQL Server uses $wgDBmwschema,
 349                 // and everything else doesn't use a schema (e.g. null)
 350                 // Although postgres and oracle support schemas, we don't use them (yet)
 351                 // to maintain backwards compatibility
 352                 $defaultSchemas = [
 353                         'mssql' => 'get from global',
 354                 ];
 355
 356                 $class = 'Database' . ucfirst( $driver );
 357                 if ( class_exists( $class ) && is_subclass_of( $class, 'IDatabase' ) ) {
 358                         // Resolve some defaults for b/c
 359                         $p['host'] = isset( $p['host'] ) ? $p['host'] : false;
 360                         $p['user'] = isset( $p['user'] ) ? $p['user'] : false;
 361                         $p['password'] = isset( $p['password'] ) ? $p['password'] : false;
 362                         $p['dbname'] = isset( $p['dbname'] ) ? $p['dbname'] : false;
 363                         $p['flags'] = isset( $p['flags'] ) ? $p['flags'] : 0;
 364                         $p['variables'] = isset( $p['variables'] ) ? $p['variables'] : [];
 365                         $p['tablePrefix'] = isset( $p['tablePrefix'] ) ? $p['tablePrefix'] : '';
 366                         if ( !isset( $p['schema'] ) ) {
 367                                 $p['schema'] = isset( $defaultSchemas[$dbType] ) ? $defaultSchemas[$dbType] : null;
 368                         }
 369                         $p['foreign'] = isset( $p['foreign'] ) ? $p['foreign'] : false;
 370                         $p['cliMode'] = $wgCommandLineMode;
 371
 372                         $conn = new $class( $p );
 373                         if ( isset( $p['connLogger'] ) ) {
 374                                 $conn->connLogger = $p['connLogger'];
 375                         }
 376                         if ( isset( $p['queryLogger'] ) ) {
 377                                 $conn->queryLogger = $p['queryLogger'];
 378                         }
 379                         if ( isset( $p['errorLogger'] ) ) {
 380                                 $conn->errorLogger = $p['errorLogger'];
 381                         } else {
 382                                 $conn->errorLogger = [ MWExceptionHandler::class, 'logException' ];
 383                         }
 384                 } else {
 385                         $conn = null;
 386                 }
 387
 388                 return $conn;
 389         }
 390
 391         public function setLogger( LoggerInterface $logger ) {
 392                 $this->queryLogger = $logger;
 393         }
 394
 395         public function getServerInfo() {
 396                 return $this->getServerVersion();
 397         }
 398
 399         /**
 400          * @return string Command delimiter used by this database engine
 401          */
 402         public function getDelimiter() {
 403                 return $this->delimiter;
 404         }
 405
 406         /**
 407          * Boolean, controls output of large amounts of debug information.
 408          * @param bool|null $debug
 409          *   - true to enable debugging
 410          *   - false to disable debugging
 411          *   - omitted or null to do nothing
 412          *
 413          * @return bool Previous value of the flag
 414          * @deprecated since 1.28; use setFlag()
 415          */
 416         public function debug( $debug = null ) {
 417                 $res = $this->getFlag( DBO_DEBUG );
 418                 if ( $debug !== null ) {
 419                         $debug ? $this->setFlag( DBO_DEBUG ) : $this->clearFlag( DBO_DEBUG );
 420                 }
 421
 422                 return $res;
 423         }
 424
 425         public function bufferResults( $buffer = null ) {
 426                 $res = !$this->getFlag( DBO_NOBUFFER );
 427                 if ( $buffer !== null ) {
 428                         $buffer ? $this->clearFlag( DBO_NOBUFFER ) : $this->setFlag( DBO_NOBUFFER );
 429                 }
 430
 431                 return $res;
 432         }
 433
 434         /**
 435          * Turns on (false) or off (true) the automatic generation and sending
 436          * of a "we're sorry, but there has been a database error" page on
 437          * database errors. Default is on (false). When turned off, the
 438          * code should use lastErrno() and lastError() to handle the
 439          * situation as appropriate.
 440          *
 441          * Do not use this function outside of the Database classes.
 442          *
 443          * @param null|bool $ignoreErrors
 444          * @return bool The previous value of the flag.
 445          */
 446         protected function ignoreErrors( $ignoreErrors = null ) {
 447                 $res = $this->getFlag( DBO_IGNORE );
 448                 if ( $ignoreErrors !== null ) {
 449                         $ignoreErrors ? $this->setFlag( DBO_IGNORE ) : $this->clearFlag( DBO_IGNORE );
 450                 }
 451
 452                 return $res;
 453         }
 454
 455         public function trxLevel() {
 456                 return $this->mTrxLevel;
 457         }
 458
 459         public function trxTimestamp() {
 460                 return $this->mTrxLevel ? $this->mTrxTimestamp : null;
 461         }
 462
 463         public function tablePrefix( $prefix = null ) {
 464                 $old = $this->mTablePrefix;
 465                 $this->mTablePrefix = $prefix;
 466
 467                 return $old;
 468         }
 469
 470         public function dbSchema( $schema = null ) {
 471                 $old = $this->mSchema;
 472                 $this->mSchema = $schema;
 473
 474                 return $old;
 475         }
 476
 477         /**
 478          * Set the filehandle to copy write statements to.
 479          *
 480          * @param resource $fh File handle
 481          */
 482         public function setFileHandle( $fh ) {
 483                 $this->fileHandle = $fh;
 484         }
 485
 486         public function getLBInfo( $name = null ) {
 487                 if ( is_null( $name ) ) {
 488                         return $this->mLBInfo;
 489                 } else {
 490                         if ( array_key_exists( $name, $this->mLBInfo ) ) {
 491                                 return $this->mLBInfo[$name];
 492                         } else {
 493                                 return null;
 494                         }
 495                 }
 496         }
 497
 498         public function setLBInfo( $name, $value = null ) {
 499                 if ( is_null( $value ) ) {
 500                         $this->mLBInfo = $name;
 501                 } else {
 502                         $this->mLBInfo[$name] = $value;
 503                 }
 504         }
 505
 506         public function setLazyMasterHandle( IDatabase $conn ) {
 507                 $this->lazyMasterHandle = $conn;
 508         }
 509
 510         /**
 511          * @return IDatabase|null
 512          * @see setLazyMasterHandle()
 513          * @since 1.27
 514          */
 515         public function getLazyMasterHandle() {
 516                 return $this->lazyMasterHandle;
 517         }
 518
 519         /**
 520          * @param TransactionProfiler $profiler
 521          * @since 1.27
 522          */
 523         public function setTransactionProfiler( TransactionProfiler $profiler ) {
 524                 $this->trxProfiler = $profiler;
 525         }
 526
 527         /**
 528          * Returns true if this database supports (and uses) cascading deletes
 529          *
 530          * @return bool
 531          */
 532         public function cascadingDeletes() {
 533                 return false;
 534         }
 535
 536         /**
 537          * Returns true if this database supports (and uses) triggers (e.g. on the page table)
 538          *
 539          * @return bool
 540          */
 541         public function cleanupTriggers() {
 542                 return false;
 543         }
 544
 545         /**
 546          * Returns true if this database is strict about what can be put into an IP field.
 547          * Specifically, it uses a NULL value instead of an empty string.
 548          *
 549          * @return bool
 550          */
 551         public function strictIPs() {
 552                 return false;
 553         }
 554
 555         /**
 556          * Returns true if this database uses timestamps rather than integers
 557          *
 558          * @return bool
 559          */
 560         public function realTimestamps() {
 561                 return false;
 562         }
 563
 564         public function implicitGroupby() {
 565                 return true;
 566         }
 567
 568         public function implicitOrderby() {
 569                 return true;
 570         }
 571
 572         /**
 573          * Returns true if this database can do a native search on IP columns
 574          * e.g. this works as expected: .. WHERE rc_ip = '127.42.12.102/32';
 575          *
 576          * @return bool
 577          */
 578         public function searchableIPs() {
 579                 return false;
 580         }
 581
 582         /**
 583          * Returns true if this database can use functional indexes
 584          *
 585          * @return bool
 586          */
 587         public function functionalIndexes() {
 588                 return false;
 589         }
 590
 591         public function lastQuery() {
 592                 return $this->mLastQuery;
 593         }
 594
 595         public function doneWrites() {
 596                 return (bool)$this->mDoneWrites;
 597         }
 598
 599         public function lastDoneWrites() {
 600                 return $this->mDoneWrites ?: false;
 601         }
 602
 603         public function writesPending() {
 604                 return $this->mTrxLevel && $this->mTrxDoneWrites;
 605         }
 606
 607         public function writesOrCallbacksPending() {
 608                 return $this->mTrxLevel && (
 609                         $this->mTrxDoneWrites || $this->mTrxIdleCallbacks || $this->mTrxPreCommitCallbacks
 610                 );
 611         }
 612
 613         public function pendingWriteQueryDuration( $type = self::ESTIMATE_TOTAL ) {
 614                 if ( !$this->mTrxLevel ) {
 615                         return false;
 616                 } elseif ( !$this->mTrxDoneWrites ) {
 617                         return 0.0;
 618                 }
 619
 620                 switch ( $type ) {
 621                         case self::ESTIMATE_DB_APPLY:
 622                                 $this->ping( $rtt );
 623                                 $rttAdjTotal = $this->mTrxWriteAdjQueryCount * $rtt;
 624                                 $applyTime = max( $this->mTrxWriteAdjDuration - $rttAdjTotal, 0 );
 625                                 // For omitted queries, make them count as something at least
 626                                 $omitted = $this->mTrxWriteQueryCount - $this->mTrxWriteAdjQueryCount;
 627                                 $applyTime += self::TINY_WRITE_SEC * $omitted;
 628
 629                                 return $applyTime;
 630                         default: // everything
 631                                 return $this->mTrxWriteDuration;
 632                 }
 633         }
 634
 635         public function pendingWriteCallers() {
 636                 return $this->mTrxLevel ? $this->mTrxWriteCallers : [];
 637         }
 638
 639         public function isOpen() {
 640                 return $this->mOpened;
 641         }
 642
 643         public function setFlag( $flag, $remember = self::REMEMBER_NOTHING ) {
 644                 if ( $remember === self::REMEMBER_PRIOR ) {
 645                         array_push( $this->priorFlags, $this->mFlags );
 646                 }
 647                 $this->mFlags |= $flag;
 648         }
 649
 650         public function clearFlag( $flag, $remember = self::REMEMBER_NOTHING ) {
 651                 if ( $remember === self::REMEMBER_PRIOR ) {
 652                         array_push( $this->priorFlags, $this->mFlags );
 653                 }
 654                 $this->mFlags &= ~$flag;
 655         }
 656
 657         public function restoreFlags( $state = self::RESTORE_PRIOR ) {
 658                 if ( !$this->priorFlags ) {
 659                         return;
 660                 }
 661
 662                 if ( $state === self::RESTORE_INITIAL ) {
 663                         $this->mFlags = reset( $this->priorFlags );
 664                         $this->priorFlags = [];
 665                 } else {
 666                         $this->mFlags = array_pop( $this->priorFlags );
 667                 }
 668         }
 669
 670         public function getFlag( $flag ) {
 671                 return !!( $this->mFlags & $flag );
 672         }
 673
 674         public function getProperty( $name ) {
 675                 return $this->$name;
 676         }
 677
 678         public function getWikiID() {
 679                 if ( $this->mTablePrefix ) {
 680                         return "{$this->mDBname}-{$this->mTablePrefix}";
 681                 } else {
 682                         return $this->mDBname;
 683                 }
 684         }
 685
 686         /**
 687          * Get information about an index into an object
 688          * @param string $table Table name
 689          * @param string $index Index name
 690          * @param string $fname Calling function name
 691          * @return mixed Database-specific index description class or false if the index does not exist
 692          */
 693         abstract function indexInfo( $table, $index, $fname = __METHOD__ );
 694
 695         /**
 696          * Wrapper for addslashes()
 697          *
 698          * @param string $s String to be slashed.
 699          * @return string Slashed string.
 700          */
 701         abstract function strencode( $s );
 702
 703         /**
 704          * Called by serialize. Throw an exception when DB connection is serialized.
 705          * This causes problems on some database engines because the connection is
 706          * not restored on unserialize.
 707          */
 708         public function __sleep() {
 709                 throw new RuntimeException( 'Database serialization may cause problems, since ' .
 710                         'the connection is not restored on wakeup.' );
 711         }
 712
 713         protected function installErrorHandler() {
 714                 $this->mPHPError = false;
 715                 $this->htmlErrors = ini_set( 'html_errors', '0' );
 716                 set_error_handler( [ $this, 'connectionerrorLogger' ] );
 717         }
 718
 719         /**
 720          * @return bool|string
 721          */
 722         protected function restoreErrorHandler() {
 723                 restore_error_handler();
 724                 if ( $this->htmlErrors !== false ) {
 725                         ini_set( 'html_errors', $this->htmlErrors );
 726                 }
 727                 if ( $this->mPHPError ) {
 728                         $error = preg_replace( '!\[<a.*</a>\]!', '', $this->mPHPError );
 729                         $error = preg_replace( '!^.*?:\s?(.*)$!', '$1', $error );
 730
 731                         return $error;
 732                 } else {
 733                         return false;
 734                 }
 735         }
 736
 737         /**
 738          * @param int $errno
 739          * @param string $errstr
 740          */
 741         public function connectionerrorLogger( $errno, $errstr ) {
 742                 $this->mPHPError = $errstr;
 743         }
 744
 745         /**
 746          * Create a log context to pass to PSR logging functions.
 747          *
 748          * @param array $extras Additional data to add to context
 749          * @return array
 750          */
 751         protected function getLogContext( array $extras = [] ) {
 752                 return array_merge(
 753                         [
 754                                 'db_server' => $this->mServer,
 755                                 'db_name' => $this->mDBname,
 756                                 'db_user' => $this->mUser,
 757                         ],
 758                         $extras
 759                 );
 760         }
 761
 762         public function close() {
 763                 if ( $this->mConn ) {
 764                         if ( $this->trxLevel() ) {
 765                                 $this->commit( __METHOD__, self::FLUSHING_INTERNAL );
 766                         }
 767
 768                         $closed = $this->closeConnection();
 769                         $this->mConn = false;
 770                 } elseif ( $this->mTrxIdleCallbacks || $this->mTrxEndCallbacks ) { // sanity
 771                         throw new RuntimeException( "Transaction callbacks still pending." );
 772                 } else {
 773                         $closed = true;
 774                 }
 775                 $this->mOpened = false;
 776
 777                 return $closed;
 778         }
 779
 780         /**
 781          * Make sure isOpen() returns true as a sanity check
 782          *
 783          * @throws DBUnexpectedError
 784          */
 785         protected function assertOpen() {
 786                 if ( !$this->isOpen() ) {
 787                         throw new DBUnexpectedError( $this, "DB connection was already closed." );
 788                 }
 789         }
 790
 791         /**
 792          * Closes underlying database connection
 793          * @since 1.20
 794          * @return bool Whether connection was closed successfully
 795          */
 796         abstract protected function closeConnection();
 797
 798         function reportConnectionError( $error = 'Unknown error' ) {
 799                 $myError = $this->lastError();
 800                 if ( $myError ) {
 801                         $error = $myError;
 802                 }
 803
 804                 # New method
 805                 throw new DBConnectionError( $this, $error );
 806         }
 807
 808         /**
 809          * The DBMS-dependent part of query()
 810          *
 811          * @param string $sql SQL query.
 812          * @return ResultWrapper|bool Result object to feed to fetchObject,
 813          *   fetchRow, ...; or false on failure
 814          */
 815         abstract protected function doQuery( $sql );
 816
 817         /**
 818          * Determine whether a query writes to the DB.
 819          * Should return true if unsure.
 820          *
 821          * @param string $sql
 822          * @return bool
 823          */
 824         protected function isWriteQuery( $sql ) {
 825                 return !preg_match(
 826                         '/^(?:SELECT|BEGIN|ROLLBACK|COMMIT|SET|SHOW|EXPLAIN|\(SELECT)\b/i', $sql );
 827         }
 828
 829         /**
 830          * @param $sql
 831          * @return string|null
 832          */
 833         protected function getQueryVerb( $sql ) {
 834                 return preg_match( '/^\s*([a-z]+)/i', $sql, $m ) ? strtoupper( $m[1] ) : null;
 835         }
 836
 837         /**
 838          * Determine whether a SQL statement is sensitive to isolation level.
 839          * A SQL statement is considered transactable if its result could vary
 840          * depending on the transaction isolation level. Operational commands
 841          * such as 'SET' and 'SHOW' are not considered to be transactable.
 842          *
 843          * @param string $sql
 844          * @return bool
 845          */
 846         protected function isTransactableQuery( $sql ) {
 847                 $verb = $this->getQueryVerb( $sql );
 848                 return !in_array( $verb, [ 'BEGIN', 'COMMIT', 'ROLLBACK', 'SHOW', 'SET' ], true );
 849         }
 850
 851         public function query( $sql, $fname = __METHOD__, $tempIgnore = false ) {
 852                 global $wgUser;
 853
 854                 $priorWritesPending = $this->writesOrCallbacksPending();
 855                 $this->mLastQuery = $sql;
 856
 857                 $isWrite = $this->isWriteQuery( $sql );
 858                 if ( $isWrite ) {
 859                         $reason = $this->getReadOnlyReason();
 860                         if ( $reason !== false ) {
 861                                 throw new DBReadOnlyError( $this, "Database is read-only: $reason" );
 862                         }
 863                         # Set a flag indicating that writes have been done
 864                         $this->mDoneWrites = microtime( true );
 865                 }
 866
 867                 # Add a comment for easy SHOW PROCESSLIST interpretation
 868                 if ( is_object( $wgUser ) && $wgUser->isItemLoaded( 'name' ) ) {
 869                         $userName = $wgUser->getName();
 870                         if ( mb_strlen( $userName ) > 15 ) {
 871                                 $userName = mb_substr( $userName, 0, 15 ) . '...';
 872                         }
 873                         $userName = str_replace( '/', '', $userName );
 874                 } else {
 875                         $userName = '';
 876                 }
 877
 878                 // Add trace comment to the begin of the sql string, right after the operator.
 879                 // Or, for one-word queries (like "BEGIN" or COMMIT") add it to the end (bug 42598)
 880                 $commentedSql = preg_replace( '/\s|$/', " /* $fname $userName */ ", $sql, 1 );
 881
 882                 # Start implicit transactions that wrap the request if DBO_TRX is enabled
 883                 if ( !$this->mTrxLevel && $this->getFlag( DBO_TRX )
 884                         && $this->isTransactableQuery( $sql )
 885                 ) {
 886                         $this->begin( __METHOD__ . " ($fname)", self::TRANSACTION_INTERNAL );
 887                         $this->mTrxAutomatic = true;
 888                 }
 889
 890                 # Keep track of whether the transaction has write queries pending
 891                 if ( $this->mTrxLevel && !$this->mTrxDoneWrites && $isWrite ) {
 892                         $this->mTrxDoneWrites = true;
 893                         $this->trxProfiler->transactionWritingIn(
 894                                 $this->mServer, $this->mDBname, $this->mTrxShortId );
 895                 }
 896
 897                 if ( $this->debug() ) {
 898                         $this->queryLogger->debug( "{$this->mDBname} {$commentedSql}" );
 899                 }
 900
 901                 # Avoid fatals if close() was called
 902                 $this->assertOpen();
 903
 904                 # Send the query to the server
 905                 $ret = $this->doProfiledQuery( $sql, $commentedSql, $isWrite, $fname );
 906
 907                 # Try reconnecting if the connection was lost
 908                 if ( false === $ret && $this->wasErrorReissuable() ) {
 909                         $recoverable = $this->canRecoverFromDisconnect( $sql, $priorWritesPending );
 910                         # Stash the last error values before anything might clear them
 911                         $lastError = $this->lastError();
 912                         $lastErrno = $this->lastErrno();
 913                         # Update state tracking to reflect transaction loss due to disconnection
 914                         $this->handleTransactionLoss();
 915                         if ( $this->reconnect() ) {
 916                                 $msg = __METHOD__ . ": lost connection to {$this->getServer()}; reconnected";
 917                                 $this->connLogger->warning( $msg );
 918                                 $this->queryLogger->warning(
 919                                         "$msg:\n" . ( new RuntimeException() )->getTraceAsString() );
 920
 921                                 if ( !$recoverable ) {
 922                                         # Callers may catch the exception and continue to use the DB
 923                                         $this->reportQueryError( $lastError, $lastErrno, $sql, $fname );
 924                                 } else {
 925                                         # Should be safe to silently retry the query
 926                                         $ret = $this->doProfiledQuery( $sql, $commentedSql, $isWrite, $fname );
 927                                 }
 928                         } else {
 929                                 $msg = __METHOD__ . ": lost connection to {$this->getServer()} permanently";
 930                                 $this->connLogger->error( $msg );
 931                         }
 932                 }
 933
 934                 if ( false === $ret ) {
 935                         # Deadlocks cause the entire transaction to abort, not just the statement.
 936                         # http://dev.mysql.com/doc/refman/5.7/en/innodb-error-handling.html
 937                         # https://www.postgresql.org/docs/9.1/static/explicit-locking.html
 938                         if ( $this->wasDeadlock() ) {
 939                                 if ( $this->explicitTrxActive() || $priorWritesPending ) {
 940                                         $tempIgnore = false; // not recoverable
 941                                 }
 942                                 # Update state tracking to reflect transaction loss
 943                                 $this->handleTransactionLoss();
 944                         }
 945
 946                         $this->reportQueryError(
 947                                 $this->lastError(), $this->lastErrno(), $sql, $fname, $tempIgnore );
 948                 }
 949
 950                 $res = $this->resultObject( $ret );
 951
 952                 return $res;
 953         }
 954
 955         private function doProfiledQuery( $sql, $commentedSql, $isWrite, $fname ) {
 956                 $isMaster = !is_null( $this->getLBInfo( 'master' ) );
 957                 # generalizeSQL() will probably cut down the query to reasonable
 958                 # logging size most of the time. The substr is really just a sanity check.
 959                 if ( $isMaster ) {
 960                         $queryProf = 'query-m: ' . substr( self::generalizeSQL( $sql ), 0, 255 );
 961                 } else {
 962                         $queryProf = 'query: ' . substr( self::generalizeSQL( $sql ), 0, 255 );
 963                 }
 964
 965                 # Include query transaction state
 966                 $queryProf .= $this->mTrxShortId ? " [TRX#{$this->mTrxShortId}]" : "";
 967
 968                 $startTime = microtime( true );
 969                 $this->profiler->profileIn( $queryProf );
 970                 $ret = $this->doQuery( $commentedSql );
 971                 $this->profiler->profileOut( $queryProf );
 972                 $queryRuntime = max( microtime( true ) - $startTime, 0.0 );
 973
 974                 unset( $queryProfSection ); // profile out (if set)
 975
 976                 if ( $ret !== false ) {
 977                         $this->lastPing = $startTime;
 978                         if ( $isWrite && $this->mTrxLevel ) {
 979                                 $this->updateTrxWriteQueryTime( $sql, $queryRuntime );
 980                                 $this->mTrxWriteCallers[] = $fname;
 981                         }
 982                 }
 983
 984                 if ( $sql === self::PING_QUERY ) {
 985                         $this->mRTTEstimate = $queryRuntime;
 986                 }
 987
 988                 $this->trxProfiler->recordQueryCompletion(
 989                         $queryProf, $startTime, $isWrite, $this->affectedRows()
 990                 );
 991                 MWDebug::query( $sql, $fname, $isMaster, $queryRuntime );
 992
 993                 return $ret;
 994         }
 995
 996         /**
 997          * Update the estimated run-time of a query, not counting large row lock times
 998          *
 999          * LoadBalancer can be set to rollback transactions that will create huge replication
1000          * lag. It bases this estimate off of pendingWriteQueryDuration(). Certain simple
1001          * queries, like inserting a row can take a long time due to row locking. This method
1002          * uses some simple heuristics to discount those cases.
1003          *
1004          * @param string $sql A SQL write query
1005          * @param float $runtime Total runtime, including RTT
1006          */
1007         private function updateTrxWriteQueryTime( $sql, $runtime ) {
1008                 // Whether this is indicative of replica DB runtime (except for RBR or ws_repl)
1009                 $indicativeOfReplicaRuntime = true;
1010                 if ( $runtime > self::SLOW_WRITE_SEC ) {
1011                         $verb = $this->getQueryVerb( $sql );
1012                         // insert(), upsert(), replace() are fast unless bulky in size or blocked on locks
1013                         if ( $verb === 'INSERT' ) {
1014                                 $indicativeOfReplicaRuntime = $this->affectedRows() > self::SMALL_WRITE_ROWS;
1015                         } elseif ( $verb === 'REPLACE' ) {
1016                                 $indicativeOfReplicaRuntime = $this->affectedRows() > self::SMALL_WRITE_ROWS / 2;
1017                         }
1018                 }
1019
1020                 $this->mTrxWriteDuration += $runtime;
1021                 $this->mTrxWriteQueryCount += 1;
1022                 if ( $indicativeOfReplicaRuntime ) {
1023                         $this->mTrxWriteAdjDuration += $runtime;
1024                         $this->mTrxWriteAdjQueryCount += 1;
1025                 }
1026         }
1027
1028         private function canRecoverFromDisconnect( $sql, $priorWritesPending ) {
1029                 # Transaction dropped; this can mean lost writes, or REPEATABLE-READ snapshots.
1030                 # Dropped connections also mean that named locks are automatically released.
1031                 # Only allow error suppression in autocommit mode or when the lost transaction
1032                 # didn't matter anyway (aside from DBO_TRX snapshot loss).
1033                 if ( $this->mNamedLocksHeld ) {
1034                         return false; // possible critical section violation
1035                 } elseif ( $sql === 'COMMIT' ) {
1036                         return !$priorWritesPending; // nothing written anyway? (T127428)
1037                 } elseif ( $sql === 'ROLLBACK' ) {
1038                         return true; // transaction lost...which is also what was requested :)
1039                 } elseif ( $this->explicitTrxActive() ) {
1040                         return false; // don't drop atomocity
1041                 } elseif ( $priorWritesPending ) {
1042                         return false; // prior writes lost from implicit transaction
1043                 }
1044
1045                 return true;
1046         }
1047
1048         private function handleTransactionLoss() {
1049                 $this->mTrxLevel = 0;
1050                 $this->mTrxIdleCallbacks = []; // bug 65263
1051                 $this->mTrxPreCommitCallbacks = []; // bug 65263
1052                 try {
1053                         // Handle callbacks in mTrxEndCallbacks
1054                         $this->runOnTransactionIdleCallbacks( self::TRIGGER_ROLLBACK );
1055                         $this->runTransactionListenerCallbacks( self::TRIGGER_ROLLBACK );
1056                         return null;
1057                 } catch ( Exception $e ) {
1058                         // Already logged; move on...
1059                         return $e;
1060                 }
1061         }
1062
1063         public function reportQueryError( $error, $errno, $sql, $fname, $tempIgnore = false ) {
1064                 if ( $this->ignoreErrors() || $tempIgnore ) {
1065                         $this->queryLogger->debug( "SQL ERROR (ignored): $error\n" );
1066                 } else {
1067                         $sql1line = mb_substr( str_replace( "\n", "\\n", $sql ), 0, 5 * 1024 );
1068                         $this->queryLogger->error(
1069                                 "{fname}\t{db_server}\t{errno}\t{error}\t{sql1line}",
1070                                 $this->getLogContext( [
1071                                         'method' => __METHOD__,
1072                                         'errno' => $errno,
1073                                         'error' => $error,
1074                                         'sql1line' => $sql1line,
1075                                         'fname' => $fname,
1076                                 ] )
1077                         );
1078                         $this->queryLogger->debug( "SQL ERROR: " . $error . "\n" );
1079                         throw new DBQueryError( $this, $error, $errno, $sql, $fname );
1080                 }
1081         }
1082
1083         /**
1084          * Intended to be compatible with the PEAR::DB wrapper functions.
1085          * http://pear.php.net/manual/en/package.database.db.intro-execute.php
1086          *
1087          * ? = scalar value, quoted as necessary
1088          * ! = raw SQL bit (a function for instance)
1089          * & = filename; reads the file and inserts as a blob
1090          *     (we don't use this though...)
1091          *
1092          * @param string $sql
1093          * @param string $func
1094          *
1095          * @return array
1096          */
1097         protected function prepare( $sql, $func = __METHOD__ ) {
1098                 /* MySQL doesn't support prepared statements (yet), so just
1099                  * pack up the query for reference. We'll manually replace
1100                  * the bits later.
1101                  */
1102                 return [ 'query' => $sql, 'func' => $func ];
1103         }
1104
1105         /**
1106          * Free a prepared query, generated by prepare().
1107          * @param string $prepared
1108          */
1109         protected function freePrepared( $prepared ) {
1110                 /* No-op by default */
1111         }
1112
1113         /**
1114          * Execute a prepared query with the various arguments
1115          * @param string $prepared The prepared sql
1116          * @param mixed $args Either an array here, or put scalars as varargs
1117          *
1118          * @return ResultWrapper
1119          */
1120         public function execute( $prepared, $args = null ) {
1121                 if ( !is_array( $args ) ) {
1122                         # Pull the var args
1123                         $args = func_get_args();
1124                         array_shift( $args );
1125                 }
1126
1127                 $sql = $this->fillPrepared( $prepared['query'], $args );
1128
1129                 return $this->query( $sql, $prepared['func'] );
1130         }
1131
1132         /**
1133          * For faking prepared SQL statements on DBs that don't support it directly.
1134          *
1135          * @param string $preparedQuery A 'preparable' SQL statement
1136          * @param array $args Array of Arguments to fill it with
1137          * @return string Executable SQL
1138          */
1139         public function fillPrepared( $preparedQuery, $args ) {
1140                 reset( $args );
1141                 $this->preparedArgs =& $args;
1142
1143                 return preg_replace_callback( '/(\\\\[?!&]|[?!&])/',
1144                         [ &$this, 'fillPreparedArg' ], $preparedQuery );
1145         }
1146
1147         /**
1148          * preg_callback func for fillPrepared()
1149          * The arguments should be in $this->preparedArgs and must not be touched
1150          * while we're doing this.
1151          *
1152          * @param array $matches
1153          * @throws DBUnexpectedError
1154          * @return string
1155          */
1156         protected function fillPreparedArg( $matches ) {
1157                 switch ( $matches[1] ) {
1158                         case '\\?':
1159                                 return '?';
1160                         case '\\!':
1161                                 return '!';
1162                         case '\\&':
1163                                 return '&';
1164                 }
1165
1166                 list( /* $n */, $arg ) = each( $this->preparedArgs );
1167
1168                 switch ( $matches[1] ) {
1169                         case '?':
1170                                 return $this->addQuotes( $arg );
1171                         case '!':
1172                                 return $arg;
1173                         case '&':
1174                                 # return $this->addQuotes( file_get_contents( $arg ) );
1175                                 throw new DBUnexpectedError(
1176                                         $this,
1177                                         '& mode is not implemented. If it\'s really needed, uncomment the line above.'
1178                                 );
1179                         default:
1180                                 throw new DBUnexpectedError(
1181                                         $this,
1182                                         'Received invalid match. This should never happen!'
1183                                 );
1184                 }
1185         }
1186
1187         public function freeResult( $res ) {
1188         }
1189
1190         public function selectField(
1191                 $table, $var, $cond = '', $fname = __METHOD__, $options = []
1192         ) {
1193                 if ( $var === '*' ) { // sanity
1194                         throw new DBUnexpectedError( $this, "Cannot use a * field: got '$var'" );
1195                 }
1196
1197                 if ( !is_array( $options ) ) {
1198                         $options = [ $options ];
1199                 }
1200
1201                 $options['LIMIT'] = 1;
1202
1203                 $res = $this->select( $table, $var, $cond, $fname, $options );
1204                 if ( $res === false || !$this->numRows( $res ) ) {
1205                         return false;
1206                 }
1207
1208                 $row = $this->fetchRow( $res );
1209
1210                 if ( $row !== false ) {
1211                         return reset( $row );
1212                 } else {
1213                         return false;
1214                 }
1215         }
1216
1217         public function selectFieldValues(
1218                 $table, $var, $cond = '', $fname = __METHOD__, $options = [], $join_conds = []
1219         ) {
1220                 if ( $var === '*' ) { // sanity
1221                         throw new DBUnexpectedError( $this, "Cannot use a * field" );
1222                 } elseif ( !is_string( $var ) ) { // sanity
1223                         throw new DBUnexpectedError( $this, "Cannot use an array of fields" );
1224                 }
1225
1226                 if ( !is_array( $options ) ) {
1227                         $options = [ $options ];
1228                 }
1229
1230                 $res = $this->select( $table, $var, $cond, $fname, $options, $join_conds );
1231                 if ( $res === false ) {
1232                         return false;
1233                 }
1234
1235                 $values = [];
1236                 foreach ( $res as $row ) {
1237                         $values[] = $row->$var;
1238                 }
1239
1240                 return $values;
1241         }
1242
1243         /**
1244          * Returns an optional USE INDEX clause to go after the table, and a
1245          * string to go at the end of the query.
1246          *
1247          * @param array $options Associative array of options to be turned into
1248          *   an SQL query, valid keys are listed in the function.
1249          * @return array
1250          * @see DatabaseBase::select()
1251          */
1252         public function makeSelectOptions( $options ) {
1253                 $preLimitTail = $postLimitTail = '';
1254                 $startOpts = '';
1255
1256                 $noKeyOptions = [];
1257
1258                 foreach ( $options as $key => $option ) {
1259                         if ( is_numeric( $key ) ) {
1260                                 $noKeyOptions[$option] = true;
1261                         }
1262                 }
1263
1264                 $preLimitTail .= $this->makeGroupByWithHaving( $options );
1265
1266                 $preLimitTail .= $this->makeOrderBy( $options );
1267
1268                 // if (isset($options['LIMIT'])) {
1269                 //      $tailOpts .= $this->limitResult('', $options['LIMIT'],
1270                 //              isset($options['OFFSET']) ? $options['OFFSET']
1271                 //              : false);
1272                 // }
1273
1274                 if ( isset( $noKeyOptions['FOR UPDATE'] ) ) {
1275                         $postLimitTail .= ' FOR UPDATE';
1276                 }
1277
1278                 if ( isset( $noKeyOptions['LOCK IN SHARE MODE'] ) ) {
1279                         $postLimitTail .= ' LOCK IN SHARE MODE';
1280                 }
1281
1282                 if ( isset( $noKeyOptions['DISTINCT'] ) || isset( $noKeyOptions['DISTINCTROW'] ) ) {
1283                         $startOpts .= 'DISTINCT';
1284                 }
1285
1286                 # Various MySQL extensions
1287                 if ( isset( $noKeyOptions['STRAIGHT_JOIN'] ) ) {
1288                         $startOpts .= ' /*! STRAIGHT_JOIN */';
1289                 }
1290
1291                 if ( isset( $noKeyOptions['HIGH_PRIORITY'] ) ) {
1292                         $startOpts .= ' HIGH_PRIORITY';
1293                 }
1294
1295                 if ( isset( $noKeyOptions['SQL_BIG_RESULT'] ) ) {
1296                         $startOpts .= ' SQL_BIG_RESULT';
1297                 }
1298
1299                 if ( isset( $noKeyOptions['SQL_BUFFER_RESULT'] ) ) {
1300                         $startOpts .= ' SQL_BUFFER_RESULT';
1301                 }
1302
1303                 if ( isset( $noKeyOptions['SQL_SMALL_RESULT'] ) ) {
1304                         $startOpts .= ' SQL_SMALL_RESULT';
1305                 }
1306
1307                 if ( isset( $noKeyOptions['SQL_CALC_FOUND_ROWS'] ) ) {
1308                         $startOpts .= ' SQL_CALC_FOUND_ROWS';
1309                 }
1310
1311                 if ( isset( $noKeyOptions['SQL_CACHE'] ) ) {
1312                         $startOpts .= ' SQL_CACHE';
1313                 }
1314
1315                 if ( isset( $noKeyOptions['SQL_NO_CACHE'] ) ) {
1316                         $startOpts .= ' SQL_NO_CACHE';
1317                 }
1318
1319                 if ( isset( $options['USE INDEX'] ) && is_string( $options['USE INDEX'] ) ) {
1320                         $useIndex = $this->useIndexClause( $options['USE INDEX'] );
1321                 } else {
1322                         $useIndex = '';
1323                 }
1324                 if ( isset( $options['IGNORE INDEX'] ) && is_string( $options['IGNORE INDEX'] ) ) {
1325                         $ignoreIndex = $this->ignoreIndexClause( $options['IGNORE INDEX'] );
1326                 } else {
1327                         $ignoreIndex = '';
1328                 }
1329
1330                 return [ $startOpts, $useIndex, $preLimitTail, $postLimitTail, $ignoreIndex ];
1331         }
1332
1333         /**
1334          * Returns an optional GROUP BY with an optional HAVING
1335          *
1336          * @param array $options Associative array of options
1337          * @return string
1338          * @see DatabaseBase::select()
1339          * @since 1.21
1340          */
1341         public function makeGroupByWithHaving( $options ) {
1342                 $sql = '';
1343                 if ( isset( $options['GROUP BY'] ) ) {
1344                         $gb = is_array( $options['GROUP BY'] )
1345                                 ? implode( ',', $options['GROUP BY'] )
1346                                 : $options['GROUP BY'];
1347                         $sql .= ' GROUP BY ' . $gb;
1348                 }
1349                 if ( isset( $options['HAVING'] ) ) {
1350                         $having = is_array( $options['HAVING'] )
1351                                 ? $this->makeList( $options['HAVING'], LIST_AND )
1352                                 : $options['HAVING'];
1353                         $sql .= ' HAVING ' . $having;
1354                 }
1355
1356                 return $sql;
1357         }
1358
1359         /**
1360          * Returns an optional ORDER BY
1361          *
1362          * @param array $options Associative array of options
1363          * @return string
1364          * @see DatabaseBase::select()
1365          * @since 1.21
1366          */
1367         public function makeOrderBy( $options ) {
1368                 if ( isset( $options['ORDER BY'] ) ) {
1369                         $ob = is_array( $options['ORDER BY'] )
1370                                 ? implode( ',', $options['ORDER BY'] )
1371                                 : $options['ORDER BY'];
1372
1373                         return ' ORDER BY ' . $ob;
1374                 }
1375
1376                 return '';
1377         }
1378
1379         // See IDatabase::select for the docs for this function
1380         public function select( $table, $vars, $conds = '', $fname = __METHOD__,
1381                 $options = [], $join_conds = [] ) {
1382                 $sql = $this->selectSQLText( $table, $vars, $conds, $fname, $options, $join_conds );
1383
1384                 return $this->query( $sql, $fname );
1385         }
1386
1387         public function selectSQLText( $table, $vars, $conds = '', $fname = __METHOD__,
1388                 $options = [], $join_conds = []
1389         ) {
1390                 if ( is_array( $vars ) ) {
1391                         $vars = implode( ',', $this->fieldNamesWithAlias( $vars ) );
1392                 }
1393
1394                 $options = (array)$options;
1395                 $useIndexes = ( isset( $options['USE INDEX'] ) && is_array( $options['USE INDEX'] ) )
1396                         ? $options['USE INDEX']
1397                         : [];
1398                 $ignoreIndexes = ( isset( $options['IGNORE INDEX'] ) && is_array( $options['IGNORE INDEX'] ) )
1399                         ? $options['IGNORE INDEX']
1400                         : [];
1401
1402                 if ( is_array( $table ) ) {
1403                         $from = ' FROM ' .
1404                                 $this->tableNamesWithIndexClauseOrJOIN( $table, $useIndexes, $ignoreIndexes, $join_conds );
1405                 } elseif ( $table != '' ) {
1406                         if ( $table[0] == ' ' ) {
1407                                 $from = ' FROM ' . $table;
1408                         } else {
1409                                 $from = ' FROM ' .
1410                                         $this->tableNamesWithIndexClauseOrJOIN( [ $table ], $useIndexes, $ignoreIndexes, [] );
1411                         }
1412                 } else {
1413                         $from = '';
1414                 }
1415
1416                 list( $startOpts, $useIndex, $preLimitTail, $postLimitTail, $ignoreIndex ) =
1417                         $this->makeSelectOptions( $options );
1418
1419                 if ( !empty( $conds ) ) {
1420                         if ( is_array( $conds ) ) {
1421                                 $conds = $this->makeList( $conds, LIST_AND );
1422                         }
1423                         $sql = "SELECT $startOpts $vars $from $useIndex $ignoreIndex WHERE $conds $preLimitTail";
1424                 } else {
1425                         $sql = "SELECT $startOpts $vars $from $useIndex $ignoreIndex $preLimitTail";
1426                 }
1427
1428                 if ( isset( $options['LIMIT'] ) ) {
1429                         $sql = $this->limitResult( $sql, $options['LIMIT'],
1430                                 isset( $options['OFFSET'] ) ? $options['OFFSET'] : false );
1431                 }
1432                 $sql = "$sql $postLimitTail";
1433
1434                 if ( isset( $options['EXPLAIN'] ) ) {
1435                         $sql = 'EXPLAIN ' . $sql;
1436                 }
1437
1438                 return $sql;
1439         }
1440
1441         public function selectRow( $table, $vars, $conds, $fname = __METHOD__,
1442                 $options = [], $join_conds = []
1443         ) {
1444                 $options = (array)$options;
1445                 $options['LIMIT'] = 1;
1446                 $res = $this->select( $table, $vars, $conds, $fname, $options, $join_conds );
1447
1448                 if ( $res === false ) {
1449                         return false;
1450                 }
1451
1452                 if ( !$this->numRows( $res ) ) {
1453                         return false;
1454                 }
1455
1456                 $obj = $this->fetchObject( $res );
1457
1458                 return $obj;
1459         }
1460
1461         public function estimateRowCount(
1462                 $table, $vars = '*', $conds = '', $fname = __METHOD__, $options = []
1463         ) {
1464                 $rows = 0;
1465                 $res = $this->select( $table, [ 'rowcount' => 'COUNT(*)' ], $conds, $fname, $options );
1466
1467                 if ( $res ) {
1468                         $row = $this->fetchRow( $res );
1469                         $rows = ( isset( $row['rowcount'] ) ) ? (int)$row['rowcount'] : 0;
1470                 }
1471
1472                 return $rows;
1473         }
1474
1475         public function selectRowCount(
1476                 $tables, $vars = '*', $conds = '', $fname = __METHOD__, $options = [], $join_conds = []
1477         ) {
1478                 $rows = 0;
1479                 $sql = $this->selectSQLText( $tables, '1', $conds, $fname, $options, $join_conds );
1480                 $res = $this->query( "SELECT COUNT(*) AS rowcount FROM ($sql) tmp_count", $fname );
1481
1482                 if ( $res ) {
1483                         $row = $this->fetchRow( $res );
1484                         $rows = ( isset( $row['rowcount'] ) ) ? (int)$row['rowcount'] : 0;
1485                 }
1486
1487                 return $rows;
1488         }
1489
1490         /**
1491          * Removes most variables from an SQL query and replaces them with X or N for numbers.
1492          * It's only slightly flawed. Don't use for anything important.
1493          *
1494          * @param string $sql A SQL Query
1495          *
1496          * @return string
1497          */
1498         protected static function generalizeSQL( $sql ) {
1499                 # This does the same as the regexp below would do, but in such a way
1500                 # as to avoid crashing php on some large strings.
1501                 # $sql = preg_replace( "/'([^\\\\']|\\\\.)*'|\"([^\\\\\"]|\\\\.)*\"/", "'X'", $sql );
1502
1503                 $sql = str_replace( "\\\\", '', $sql );
1504                 $sql = str_replace( "\\'", '', $sql );
1505                 $sql = str_replace( "\\\"", '', $sql );
1506                 $sql = preg_replace( "/'.*'/s", "'X'", $sql );
1507                 $sql = preg_replace( '/".*"/s', "'X'", $sql );
1508
1509                 # All newlines, tabs, etc replaced by single space
1510                 $sql = preg_replace( '/\s+/', ' ', $sql );
1511
1512                 # All numbers => N,
1513                 # except the ones surrounded by characters, e.g. l10n
1514                 $sql = preg_replace( '/-?\d+(,-?\d+)+/s', 'N,...,N', $sql );
1515                 $sql = preg_replace( '/(?<![a-zA-Z])-?\d+(?![a-zA-Z])/s', 'N', $sql );
1516
1517                 return $sql;
1518         }
1519
1520         public function fieldExists( $table, $field, $fname = __METHOD__ ) {
1521                 $info = $this->fieldInfo( $table, $field );
1522
1523                 return (bool)$info;
1524         }
1525
1526         public function indexExists( $table, $index, $fname = __METHOD__ ) {
1527                 if ( !$this->tableExists( $table ) ) {
1528                         return null;
1529                 }
1530
1531                 $info = $this->indexInfo( $table, $index, $fname );
1532                 if ( is_null( $info ) ) {
1533                         return null;
1534                 } else {
1535                         return $info !== false;
1536                 }
1537         }
1538
1539         public function tableExists( $table, $fname = __METHOD__ ) {
1540                 $table = $this->tableName( $table );
1541                 $old = $this->ignoreErrors( true );
1542                 $res = $this->query( "SELECT 1 FROM $table LIMIT 1", $fname );
1543                 $this->ignoreErrors( $old );
1544
1545                 return (bool)$res;
1546         }
1547
1548         public function indexUnique( $table, $index ) {
1549                 $indexInfo = $this->indexInfo( $table, $index );
1550
1551                 if ( !$indexInfo ) {
1552                         return null;
1553                 }
1554
1555                 return !$indexInfo[0]->Non_unique;
1556         }
1557
1558         /**
1559          * Helper for DatabaseBase::insert().
1560          *
1561          * @param array $options
1562          * @return string
1563          */
1564         protected function makeInsertOptions( $options ) {
1565                 return implode( ' ', $options );
1566         }
1567
1568         public function insert( $table, $a, $fname = __METHOD__, $options = [] ) {
1569                 # No rows to insert, easy just return now
1570                 if ( !count( $a ) ) {
1571                         return true;
1572                 }
1573
1574                 $table = $this->tableName( $table );
1575
1576                 if ( !is_array( $options ) ) {
1577                         $options = [ $options ];
1578                 }
1579
1580                 $fh = null;
1581                 if ( isset( $options['fileHandle'] ) ) {
1582                         $fh = $options['fileHandle'];
1583                 }
1584                 $options = $this->makeInsertOptions( $options );
1585
1586                 if ( isset( $a[0] ) && is_array( $a[0] ) ) {
1587                         $multi = true;
1588                         $keys = array_keys( $a[0] );
1589                 } else {
1590                         $multi = false;
1591                         $keys = array_keys( $a );
1592                 }
1593
1594                 $sql = 'INSERT ' . $options .
1595                         " INTO $table (" . implode( ',', $keys ) . ') VALUES ';
1596
1597                 if ( $multi ) {
1598                         $first = true;
1599                         foreach ( $a as $row ) {
1600                                 if ( $first ) {
1601                                         $first = false;
1602                                 } else {
1603                                         $sql .= ',';
1604                                 }
1605                                 $sql .= '(' . $this->makeList( $row ) . ')';
1606                         }
1607                 } else {
1608                         $sql .= '(' . $this->makeList( $a ) . ')';
1609                 }
1610
1611                 if ( $fh !== null && false === fwrite( $fh, $sql ) ) {
1612                         return false;
1613                 } elseif ( $fh !== null ) {
1614                         return true;
1615                 }
1616
1617                 return (bool)$this->query( $sql, $fname );
1618         }
1619
1620         /**
1621          * Make UPDATE options array for DatabaseBase::makeUpdateOptions
1622          *
1623          * @param array $options
1624          * @return array
1625          */
1626         protected function makeUpdateOptionsArray( $options ) {
1627                 if ( !is_array( $options ) ) {
1628                         $options = [ $options ];
1629                 }
1630
1631                 $opts = [];
1632
1633                 if ( in_array( 'LOW_PRIORITY', $options ) ) {
1634                         $opts[] = $this->lowPriorityOption();
1635                 }
1636
1637                 if ( in_array( 'IGNORE', $options ) ) {
1638                         $opts[] = 'IGNORE';
1639                 }
1640
1641                 return $opts;
1642         }
1643
1644         /**
1645          * Make UPDATE options for the DatabaseBase::update function
1646          *
1647          * @param array $options The options passed to DatabaseBase::update
1648          * @return string
1649          */
1650         protected function makeUpdateOptions( $options ) {
1651                 $opts = $this->makeUpdateOptionsArray( $options );
1652
1653                 return implode( ' ', $opts );
1654         }
1655
1656         function update( $table, $values, $conds, $fname = __METHOD__, $options = [] ) {
1657                 $table = $this->tableName( $table );
1658                 $opts = $this->makeUpdateOptions( $options );
1659                 $sql = "UPDATE $opts $table SET " . $this->makeList( $values, LIST_SET );
1660
1661                 if ( $conds !== [] && $conds !== '*' ) {
1662                         $sql .= " WHERE " . $this->makeList( $conds, LIST_AND );
1663                 }
1664
1665                 return $this->query( $sql, $fname );
1666         }
1667
1668         public function makeList( $a, $mode = LIST_COMMA ) {
1669                 if ( !is_array( $a ) ) {
1670                         throw new DBUnexpectedError( $this, __METHOD__ . ' called with incorrect parameters' );
1671                 }
1672
1673                 $first = true;
1674                 $list = '';
1675
1676                 foreach ( $a as $field => $value ) {
1677                         if ( !$first ) {
1678                                 if ( $mode == LIST_AND ) {
1679                                         $list .= ' AND ';
1680                                 } elseif ( $mode == LIST_OR ) {
1681                                         $list .= ' OR ';
1682                                 } else {
1683                                         $list .= ',';
1684                                 }
1685                         } else {
1686                                 $first = false;
1687                         }
1688
1689                         if ( ( $mode == LIST_AND || $mode == LIST_OR ) && is_numeric( $field ) ) {
1690                                 $list .= "($value)";
1691                         } elseif ( ( $mode == LIST_SET ) && is_numeric( $field ) ) {
1692                                 $list .= "$value";
1693                         } elseif ( ( $mode == LIST_AND || $mode == LIST_OR ) && is_array( $value ) ) {
1694                                 // Remove null from array to be handled separately if found
1695                                 $includeNull = false;
1696                                 foreach ( array_keys( $value, null, true ) as $nullKey ) {
1697                                         $includeNull = true;
1698                                         unset( $value[$nullKey] );
1699                                 }
1700                                 if ( count( $value ) == 0 && !$includeNull ) {
1701                                         throw new InvalidArgumentException( __METHOD__ . ": empty input for field $field" );
1702                                 } elseif ( count( $value ) == 0 ) {
1703                                         // only check if $field is null
1704                                         $list .= "$field IS NULL";
1705                                 } else {
1706                                         // IN clause contains at least one valid element
1707                                         if ( $includeNull ) {
1708                                                 // Group subconditions to ensure correct precedence
1709                                                 $list .= '(';
1710                                         }
1711                                         if ( count( $value ) == 1 ) {
1712                                                 // Special-case single values, as IN isn't terribly efficient
1713                                                 // Don't necessarily assume the single key is 0; we don't
1714                                                 // enforce linear numeric ordering on other arrays here.
1715                                                 $value = array_values( $value )[0];
1716                                                 $list .= $field . " = " . $this->addQuotes( $value );
1717                                         } else {
1718                                                 $list .= $field . " IN (" . $this->makeList( $value ) . ") ";
1719                                         }
1720                                         // if null present in array, append IS NULL
1721                                         if ( $includeNull ) {
1722                                                 $list .= " OR $field IS NULL)";
1723                                         }
1724                                 }
1725                         } elseif ( $value === null ) {
1726                                 if ( $mode == LIST_AND || $mode == LIST_OR ) {
1727                                         $list .= "$field IS ";
1728                                 } elseif ( $mode == LIST_SET ) {
1729                                         $list .= "$field = ";
1730                                 }
1731                                 $list .= 'NULL';
1732                         } else {
1733                                 if ( $mode == LIST_AND || $mode == LIST_OR || $mode == LIST_SET ) {
1734                                         $list .= "$field = ";
1735                                 }
1736                                 $list .= $mode == LIST_NAMES ? $value : $this->addQuotes( $value );
1737                         }
1738                 }
1739
1740                 return $list;
1741         }
1742
1743         public function makeWhereFrom2d( $data, $baseKey, $subKey ) {
1744                 $conds = [];
1745
1746                 foreach ( $data as $base => $sub ) {
1747                         if ( count( $sub ) ) {
1748                                 $conds[] = $this->makeList(
1749                                         [ $baseKey => $base, $subKey => array_keys( $sub ) ],
1750                                         LIST_AND );
1751                         }
1752                 }
1753
1754                 if ( $conds ) {
1755                         return $this->makeList( $conds, LIST_OR );
1756                 } else {
1757                         // Nothing to search for...
1758                         return false;
1759                 }
1760         }
1761
1762         /**
1763          * Return aggregated value alias
1764          *
1765          * @param array $valuedata
1766          * @param string $valuename
1767          *
1768          * @return string
1769          */
1770         public function aggregateValue( $valuedata, $valuename = 'value' ) {
1771                 return $valuename;
1772         }
1773
1774         public function bitNot( $field ) {
1775                 return "(~$field)";
1776         }
1777
1778         public function bitAnd( $fieldLeft, $fieldRight ) {
1779                 return "($fieldLeft & $fieldRight)";
1780         }
1781
1782         public function bitOr( $fieldLeft, $fieldRight ) {
1783                 return "($fieldLeft | $fieldRight)";
1784         }
1785
1786         public function buildConcat( $stringList ) {
1787                 return 'CONCAT(' . implode( ',', $stringList ) . ')';
1788         }
1789
1790         public function buildGroupConcatField(
1791                 $delim, $table, $field, $conds = '', $join_conds = []
1792         ) {
1793                 $fld = "GROUP_CONCAT($field SEPARATOR " . $this->addQuotes( $delim ) . ')';
1794
1795                 return '(' . $this->selectSQLText( $table, $fld, $conds, null, [], $join_conds ) . ')';
1796         }
1797
1798         /**
1799          * @param string $field Field or column to cast
1800          * @return string
1801          * @since 1.28
1802          */
1803         public function buildStringCast( $field ) {
1804                 return $field;
1805         }
1806
1807         public function selectDB( $db ) {
1808                 # Stub. Shouldn't cause serious problems if it's not overridden, but
1809                 # if your database engine supports a concept similar to MySQL's
1810                 # databases you may as well.
1811                 $this->mDBname = $db;
1812
1813                 return true;
1814         }
1815
1816         public function getDBname() {
1817                 return $this->mDBname;
1818         }
1819
1820         public function getServer() {
1821                 return $this->mServer;
1822         }
1823
1824         /**
1825          * Format a table name ready for use in constructing an SQL query
1826          *
1827          * This does two important things: it quotes the table names to clean them up,
1828          * and it adds a table prefix if only given a table name with no quotes.
1829          *
1830          * All functions of this object which require a table name call this function
1831          * themselves. Pass the canonical name to such functions. This is only needed
1832          * when calling query() directly.
1833          *
1834          * @note This function does not sanitize user input. It is not safe to use
1835          *   this function to escape user input.
1836          * @param string $name Database table name
1837          * @param string $format One of:
1838          *   quoted - Automatically pass the table name through addIdentifierQuotes()
1839          *            so that it can be used in a query.
1840          *   raw - Do not add identifier quotes to the table name
1841          * @return string Full database name
1842          */
1843         public function tableName( $name, $format = 'quoted' ) {
1844                 # Skip the entire process when we have a string quoted on both ends.
1845                 # Note that we check the end so that we will still quote any use of
1846                 # use of `database`.table. But won't break things if someone wants
1847                 # to query a database table with a dot in the name.
1848                 if ( $this->isQuotedIdentifier( $name ) ) {
1849                         return $name;
1850                 }
1851
1852                 # Lets test for any bits of text that should never show up in a table
1853                 # name. Basically anything like JOIN or ON which are actually part of
1854                 # SQL queries, but may end up inside of the table value to combine
1855                 # sql. Such as how the API is doing.
1856                 # Note that we use a whitespace test rather than a \b test to avoid
1857                 # any remote case where a word like on may be inside of a table name
1858                 # surrounded by symbols which may be considered word breaks.
1859                 if ( preg_match( '/(^|\s)(DISTINCT|JOIN|ON|AS)(\s|$)/i', $name ) !== 0 ) {
1860                         return $name;
1861                 }
1862
1863                 # Split database and table into proper variables.
1864                 # We reverse the explode so that database.table and table both output
1865                 # the correct table.
1866                 $dbDetails = explode( '.', $name, 3 );
1867                 if ( count( $dbDetails ) == 3 ) {
1868                         list( $database, $schema, $table ) = $dbDetails;
1869                         # We don't want any prefix added in this case
1870                         $prefix = '';
1871                 } elseif ( count( $dbDetails ) == 2 ) {
1872                         list( $database, $table ) = $dbDetails;
1873                         # We don't want any prefix added in this case
1874                         # In dbs that support it, $database may actually be the schema
1875                         # but that doesn't affect any of the functionality here
1876                         $prefix = '';
1877                         $schema = null;
1878                 } else {
1879                         list( $table ) = $dbDetails;
1880                         if ( isset( $this->tableAliases[$table] ) ) {
1881                                 $database = $this->tableAliases[$table]['dbname'];
1882                                 $schema = is_string( $this->tableAliases[$table]['schema'] )
1883                                         ? $this->tableAliases[$table]['schema']
1884                                         : $this->mSchema;
1885                                 $prefix = is_string( $this->tableAliases[$table]['prefix'] )
1886                                         ? $this->tableAliases[$table]['prefix']
1887                                         : $this->mTablePrefix;
1888                         } else {
1889                                 $database = null;
1890                                 $schema = $this->mSchema; # Default schema
1891                                 $prefix = $this->mTablePrefix; # Default prefix
1892                         }
1893                 }
1894
1895                 # Quote $table and apply the prefix if not quoted.
1896                 # $tableName might be empty if this is called from Database::replaceVars()
1897                 $tableName = "{$prefix}{$table}";
1898                 if ( $format == 'quoted'
1899                         && !$this->isQuotedIdentifier( $tableName ) && $tableName !== ''
1900                 ) {
1901                         $tableName = $this->addIdentifierQuotes( $tableName );
1902                 }
1903
1904                 # Quote $schema and merge it with the table name if needed
1905                 if ( strlen( $schema ) ) {
1906                         if ( $format == 'quoted' && !$this->isQuotedIdentifier( $schema ) ) {
1907                                 $schema = $this->addIdentifierQuotes( $schema );
1908                         }
1909                         $tableName = $schema . '.' . $tableName;
1910                 }
1911
1912                 # Quote $database and merge it with the table name if needed
1913                 if ( $database !== null ) {
1914                         if ( $format == 'quoted' && !$this->isQuotedIdentifier( $database ) ) {
1915                                 $database = $this->addIdentifierQuotes( $database );
1916                         }
1917                         $tableName = $database . '.' . $tableName;
1918                 }
1919
1920                 return $tableName;
1921         }
1922
1923         /**
1924          * Fetch a number of table names into an array
1925          * This is handy when you need to construct SQL for joins
1926          *
1927          * Example:
1928          * extract( $dbr->tableNames( 'user', 'watchlist' ) );
1929          * $sql = "SELECT wl_namespace,wl_title FROM $watchlist,$user
1930          *         WHERE wl_user=user_id AND wl_user=$nameWithQuotes";
1931          *
1932          * @return array
1933          */
1934         public function tableNames() {
1935                 $inArray = func_get_args();
1936                 $retVal = [];
1937
1938                 foreach ( $inArray as $name ) {
1939                         $retVal[$name] = $this->tableName( $name );
1940                 }
1941
1942                 return $retVal;
1943         }
1944
1945         /**
1946          * Fetch a number of table names into an zero-indexed numerical array
1947          * This is handy when you need to construct SQL for joins
1948          *
1949          * Example:
1950          * list( $user, $watchlist ) = $dbr->tableNamesN( 'user', 'watchlist' );
1951          * $sql = "SELECT wl_namespace,wl_title FROM $watchlist,$user
1952          *         WHERE wl_user=user_id AND wl_user=$nameWithQuotes";
1953          *
1954          * @return array
1955          */
1956         public function tableNamesN() {
1957                 $inArray = func_get_args();
1958                 $retVal = [];
1959
1960                 foreach ( $inArray as $name ) {
1961                         $retVal[] = $this->tableName( $name );
1962                 }
1963
1964                 return $retVal;
1965         }
1966
1967         /**
1968          * Get an aliased table name
1969          * e.g. tableName AS newTableName
1970          *
1971          * @param string $name Table name, see tableName()
1972          * @param string|bool $alias Alias (optional)
1973          * @return string SQL name for aliased table. Will not alias a table to its own name
1974          */
1975         public function tableNameWithAlias( $name, $alias = false ) {
1976                 if ( !$alias || $alias == $name ) {
1977                         return $this->tableName( $name );
1978                 } else {
1979                         return $this->tableName( $name ) . ' ' . $this->addIdentifierQuotes( $alias );
1980                 }
1981         }
1982
1983         /**
1984          * Gets an array of aliased table names
1985          *
1986          * @param array $tables [ [alias] => table ]
1987          * @return string[] See tableNameWithAlias()
1988          */
1989         public function tableNamesWithAlias( $tables ) {
1990                 $retval = [];
1991                 foreach ( $tables as $alias => $table ) {
1992                         if ( is_numeric( $alias ) ) {
1993                                 $alias = $table;
1994                         }
1995                         $retval[] = $this->tableNameWithAlias( $table, $alias );
1996                 }
1997
1998                 return $retval;
1999         }
2000
2001         /**
2002          * Get an aliased field name
2003          * e.g. fieldName AS newFieldName
2004          *
2005          * @param string $name Field name
2006          * @param string|bool $alias Alias (optional)
2007          * @return string SQL name for aliased field. Will not alias a field to its own name
2008          */
2009         public function fieldNameWithAlias( $name, $alias = false ) {
2010                 if ( !$alias || (string)$alias === (string)$name ) {
2011                         return $name;
2012                 } else {
2013                         return $name . ' AS ' . $this->addIdentifierQuotes( $alias ); // PostgreSQL needs AS
2014                 }
2015         }
2016
2017         /**
2018          * Gets an array of aliased field names
2019          *
2020          * @param array $fields [ [alias] => field ]
2021          * @return string[] See fieldNameWithAlias()
2022          */
2023         public function fieldNamesWithAlias( $fields ) {
2024                 $retval = [];
2025                 foreach ( $fields as $alias => $field ) {
2026                         if ( is_numeric( $alias ) ) {
2027                                 $alias = $field;
2028                         }
2029                         $retval[] = $this->fieldNameWithAlias( $field, $alias );
2030                 }
2031
2032                 return $retval;
2033         }
2034
2035         /**
2036          * Get the aliased table name clause for a FROM clause
2037          * which might have a JOIN and/or USE INDEX or IGNORE INDEX clause
2038          *
2039          * @param array $tables ( [alias] => table )
2040          * @param array $use_index Same as for select()
2041          * @param array $ignore_index Same as for select()
2042          * @param array $join_conds Same as for select()
2043          * @return string
2044          */
2045         protected function tableNamesWithIndexClauseOrJOIN(
2046                 $tables, $use_index = [], $ignore_index = [], $join_conds = []
2047         ) {
2048                 $ret = [];
2049                 $retJOIN = [];
2050                 $use_index = (array)$use_index;
2051                 $ignore_index = (array)$ignore_index;
2052                 $join_conds = (array)$join_conds;
2053
2054                 foreach ( $tables as $alias => $table ) {
2055                         if ( !is_string( $alias ) ) {
2056                                 // No alias? Set it equal to the table name
2057                                 $alias = $table;
2058                         }
2059                         // Is there a JOIN clause for this table?
2060                         if ( isset( $join_conds[$alias] ) ) {
2061                                 list( $joinType, $conds ) = $join_conds[$alias];
2062                                 $tableClause = $joinType;
2063                                 $tableClause .= ' ' . $this->tableNameWithAlias( $table, $alias );
2064                                 if ( isset( $use_index[$alias] ) ) { // has USE INDEX?
2065                                         $use = $this->useIndexClause( implode( ',', (array)$use_index[$alias] ) );
2066                                         if ( $use != '' ) {
2067                                                 $tableClause .= ' ' . $use;
2068                                         }
2069                                 }
2070                                 if ( isset( $ignore_index[$alias] ) ) { // has IGNORE INDEX?
2071                                         $ignore = $this->ignoreIndexClause( implode( ',', (array)$ignore_index[$alias] ) );
2072                                         if ( $ignore != '' ) {
2073                                                 $tableClause .= ' ' . $ignore;
2074                                         }
2075                                 }
2076                                 $on = $this->makeList( (array)$conds, LIST_AND );
2077                                 if ( $on != '' ) {
2078                                         $tableClause .= ' ON (' . $on . ')';
2079                                 }
2080
2081                                 $retJOIN[] = $tableClause;
2082                         } elseif ( isset( $use_index[$alias] ) ) {
2083                                 // Is there an INDEX clause for this table?
2084                                 $tableClause = $this->tableNameWithAlias( $table, $alias );
2085                                 $tableClause .= ' ' . $this->useIndexClause(
2086                                         implode( ',', (array)$use_index[$alias] )
2087                                 );
2088
2089                                 $ret[] = $tableClause;
2090                         } elseif ( isset( $ignore_index[$alias] ) ) {
2091                                 // Is there an INDEX clause for this table?
2092                                 $tableClause = $this->tableNameWithAlias( $table, $alias );
2093                                 $tableClause .= ' ' . $this->ignoreIndexClause(
2094                                         implode( ',', (array)$ignore_index[$alias] )
2095                                 );
2096
2097                                 $ret[] = $tableClause;
2098                         } else {
2099                                 $tableClause = $this->tableNameWithAlias( $table, $alias );
2100
2101                                 $ret[] = $tableClause;
2102                         }
2103                 }
2104
2105                 // We can't separate explicit JOIN clauses with ',', use ' ' for those
2106                 $implicitJoins = !empty( $ret ) ? implode( ',', $ret ) : "";
2107                 $explicitJoins = !empty( $retJOIN ) ? implode( ' ', $retJOIN ) : "";
2108
2109                 // Compile our final table clause
2110                 return implode( ' ', [ $implicitJoins, $explicitJoins ] );
2111         }
2112
2113         /**
2114          * Get the name of an index in a given table.
2115          *
2116          * @param string $index
2117          * @return string
2118          */
2119         protected function indexName( $index ) {
2120                 // Backwards-compatibility hack
2121                 $renamed = [
2122                         'ar_usertext_timestamp' => 'usertext_timestamp',
2123                         'un_user_id' => 'user_id',
2124                         'un_user_ip' => 'user_ip',
2125                 ];
2126
2127                 if ( isset( $renamed[$index] ) ) {
2128                         return $renamed[$index];
2129                 } else {
2130                         return $index;
2131                 }
2132         }
2133
2134         public function addQuotes( $s ) {
2135                 if ( $s instanceof Blob ) {
2136                         $s = $s->fetch();
2137                 }
2138                 if ( $s === null ) {
2139                         return 'NULL';
2140                 } else {
2141                         # This will also quote numeric values. This should be harmless,
2142                         # and protects against weird problems that occur when they really
2143                         # _are_ strings such as article titles and string->number->string
2144                         # conversion is not 1:1.
2145                         return "'" . $this->strencode( $s ) . "'";
2146                 }
2147         }
2148
2149         /**
2150          * Quotes an identifier using `backticks` or "double quotes" depending on the database type.
2151          * MySQL uses `backticks` while basically everything else uses double quotes.
2152          * Since MySQL is the odd one out here the double quotes are our generic
2153          * and we implement backticks in DatabaseMysql.
2154          *
2155          * @param string $s
2156          * @return string
2157          */
2158         public function addIdentifierQuotes( $s ) {
2159                 return '"' . str_replace( '"', '""', $s ) . '"';
2160         }
2161
2162         /**
2163          * Returns if the given identifier looks quoted or not according to
2164          * the database convention for quoting identifiers .
2165          *
2166          * @note Do not use this to determine if untrusted input is safe.
2167          *   A malicious user can trick this function.
2168          * @param string $name
2169          * @return bool
2170          */
2171         public function isQuotedIdentifier( $name ) {
2172                 return $name[0] == '"' && substr( $name, -1, 1 ) == '"';
2173         }
2174
2175         /**
2176          * @param string $s
2177          * @return string
2178          */
2179         protected function escapeLikeInternal( $s ) {
2180                 return addcslashes( $s, '\%_' );
2181         }
2182
2183         public function buildLike() {
2184                 $params = func_get_args();
2185
2186                 if ( count( $params ) > 0 && is_array( $params[0] ) ) {
2187                         $params = $params[0];
2188                 }
2189
2190                 $s = '';
2191
2192                 foreach ( $params as $value ) {
2193                         if ( $value instanceof LikeMatch ) {
2194                                 $s .= $value->toString();
2195                         } else {
2196                                 $s .= $this->escapeLikeInternal( $value );
2197                         }
2198                 }
2199
2200                 return " LIKE {$this->addQuotes( $s )} ";
2201         }
2202
2203         public function anyChar() {
2204                 return new LikeMatch( '_' );
2205         }
2206
2207         public function anyString() {
2208                 return new LikeMatch( '%' );
2209         }
2210
2211         public function nextSequenceValue( $seqName ) {
2212                 return null;
2213         }
2214
2215         /**
2216          * USE INDEX clause. Unlikely to be useful for anything but MySQL. This
2217          * is only needed because a) MySQL must be as efficient as possible due to
2218          * its use on Wikipedia, and b) MySQL 4.0 is kind of dumb sometimes about
2219          * which index to pick. Anyway, other databases might have different
2220          * indexes on a given table. So don't bother overriding this unless you're
2221          * MySQL.
2222          * @param string $index
2223          * @return string
2224          */
2225         public function useIndexClause( $index ) {
2226                 return '';
2227         }
2228
2229         /**
2230          * IGNORE INDEX clause. Unlikely to be useful for anything but MySQL. This
2231          * is only needed because a) MySQL must be as efficient as possible due to
2232          * its use on Wikipedia, and b) MySQL 4.0 is kind of dumb sometimes about
2233          * which index to pick. Anyway, other databases might have different
2234          * indexes on a given table. So don't bother overriding this unless you're
2235          * MySQL.
2236          * @param string $index
2237          * @return string
2238          */
2239         public function ignoreIndexClause( $index ) {
2240                 return '';
2241         }
2242
2243         public function replace( $table, $uniqueIndexes, $rows, $fname = __METHOD__ ) {
2244                 $quotedTable = $this->tableName( $table );
2245
2246                 if ( count( $rows ) == 0 ) {
2247                         return;
2248                 }
2249
2250                 # Single row case
2251                 if ( !is_array( reset( $rows ) ) ) {
2252                         $rows = [ $rows ];
2253                 }
2254
2255                 // @FXIME: this is not atomic, but a trx would break affectedRows()
2256                 foreach ( $rows as $row ) {
2257                         # Delete rows which collide
2258                         if ( $uniqueIndexes ) {
2259                                 $sql = "DELETE FROM $quotedTable WHERE ";
2260                                 $first = true;
2261                                 foreach ( $uniqueIndexes as $index ) {
2262                                         if ( $first ) {
2263                                                 $first = false;
2264                                                 $sql .= '( ';
2265                                         } else {
2266                                                 $sql .= ' ) OR ( ';
2267                                         }
2268                                         if ( is_array( $index ) ) {
2269                                                 $first2 = true;
2270                                                 foreach ( $index as $col ) {
2271                                                         if ( $first2 ) {
2272                                                                 $first2 = false;
2273                                                         } else {
2274                                                                 $sql .= ' AND ';
2275                                                         }
2276                                                         $sql .= $col . '=' . $this->addQuotes( $row[$col] );
2277                                                 }
2278                                         } else {
2279                                                 $sql .= $index . '=' . $this->addQuotes( $row[$index] );
2280                                         }
2281                                 }
2282                                 $sql .= ' )';
2283                                 $this->query( $sql, $fname );
2284                         }
2285
2286                         # Now insert the row
2287                         $this->insert( $table, $row, $fname );
2288                 }
2289         }
2290
2291         /**
2292          * REPLACE query wrapper for MySQL and SQLite, which have a native REPLACE
2293          * statement.
2294          *
2295          * @param string $table Table name
2296          * @param array|string $rows Row(s) to insert
2297          * @param string $fname Caller function name
2298          *
2299          * @return ResultWrapper
2300          */
2301         protected function nativeReplace( $table, $rows, $fname ) {
2302                 $table = $this->tableName( $table );
2303
2304                 # Single row case
2305                 if ( !is_array( reset( $rows ) ) ) {
2306                         $rows = [ $rows ];
2307                 }
2308
2309                 $sql = "REPLACE INTO $table (" . implode( ',', array_keys( $rows[0] ) ) . ') VALUES ';
2310                 $first = true;
2311
2312                 foreach ( $rows as $row ) {
2313                         if ( $first ) {
2314                                 $first = false;
2315                         } else {
2316                                 $sql .= ',';
2317                         }
2318
2319                         $sql .= '(' . $this->makeList( $row ) . ')';
2320                 }
2321
2322                 return $this->query( $sql, $fname );
2323         }
2324
2325         public function upsert( $table, array $rows, array $uniqueIndexes, array $set,
2326                 $fname = __METHOD__
2327         ) {
2328                 if ( !count( $rows ) ) {
2329                         return true; // nothing to do
2330                 }
2331
2332                 if ( !is_array( reset( $rows ) ) ) {
2333                         $rows = [ $rows ];
2334                 }
2335
2336                 if ( count( $uniqueIndexes ) ) {
2337                         $clauses = []; // list WHERE clauses that each identify a single row
2338                         foreach ( $rows as $row ) {
2339                                 foreach ( $uniqueIndexes as $index ) {
2340                                         $index = is_array( $index ) ? $index : [ $index ]; // columns
2341                                         $rowKey = []; // unique key to this row
2342                                         foreach ( $index as $column ) {
2343                                                 $rowKey[$column] = $row[$column];
2344                                         }
2345                                         $clauses[] = $this->makeList( $rowKey, LIST_AND );
2346                                 }
2347                         }
2348                         $where = [ $this->makeList( $clauses, LIST_OR ) ];
2349                 } else {
2350                         $where = false;
2351                 }
2352
2353                 $useTrx = !$this->mTrxLevel;
2354                 if ( $useTrx ) {
2355                         $this->begin( $fname, self::TRANSACTION_INTERNAL );
2356                 }
2357                 try {
2358                         # Update any existing conflicting row(s)
2359                         if ( $where !== false ) {
2360                                 $ok = $this->update( $table, $set, $where, $fname );
2361                         } else {
2362                                 $ok = true;
2363                         }
2364                         # Now insert any non-conflicting row(s)
2365                         $ok = $this->insert( $table, $rows, $fname, [ 'IGNORE' ] ) && $ok;
2366                 } catch ( Exception $e ) {
2367                         if ( $useTrx ) {
2368                                 $this->rollback( $fname, self::FLUSHING_INTERNAL );
2369                         }
2370                         throw $e;
2371                 }
2372                 if ( $useTrx ) {
2373                         $this->commit( $fname, self::FLUSHING_INTERNAL );
2374                 }
2375
2376                 return $ok;
2377         }
2378
2379         public function deleteJoin( $delTable, $joinTable, $delVar, $joinVar, $conds,
2380                 $fname = __METHOD__
2381         ) {
2382                 if ( !$conds ) {
2383                         throw new DBUnexpectedError( $this, __METHOD__ . ' called with empty $conds' );
2384                 }
2385
2386                 $delTable = $this->tableName( $delTable );
2387                 $joinTable = $this->tableName( $joinTable );
2388                 $sql = "DELETE FROM $delTable WHERE $delVar IN (SELECT $joinVar FROM $joinTable ";
2389                 if ( $conds != '*' ) {
2390                         $sql .= 'WHERE ' . $this->makeList( $conds, LIST_AND );
2391                 }
2392                 $sql .= ')';
2393
2394                 $this->query( $sql, $fname );
2395         }
2396
2397         /**
2398          * Returns the size of a text field, or -1 for "unlimited"
2399          *
2400          * @param string $table
2401          * @param string $field
2402          * @return int
2403          */
2404         public function textFieldSize( $table, $field ) {
2405                 $table = $this->tableName( $table );
2406                 $sql = "SHOW COLUMNS FROM $table LIKE \"$field\";";
2407                 $res = $this->query( $sql, __METHOD__ );
2408                 $row = $this->fetchObject( $res );
2409
2410                 $m = [];
2411
2412                 if ( preg_match( '/\((.*)\)/', $row->Type, $m ) ) {
2413                         $size = $m[1];
2414                 } else {
2415                         $size = -1;
2416                 }
2417
2418                 return $size;
2419         }
2420
2421         /**
2422          * A string to insert into queries to show that they're low-priority, like
2423          * MySQL's LOW_PRIORITY. If no such feature exists, return an empty
2424          * string and nothing bad should happen.
2425          *
2426          * @return string Returns the text of the low priority option if it is
2427          *   supported, or a blank string otherwise
2428          */
2429         public function lowPriorityOption() {
2430                 return '';
2431         }
2432
2433         public function delete( $table, $conds, $fname = __METHOD__ ) {
2434                 if ( !$conds ) {
2435                         throw new DBUnexpectedError( $this, __METHOD__ . ' called with no conditions' );
2436                 }
2437
2438                 $table = $this->tableName( $table );
2439                 $sql = "DELETE FROM $table";
2440
2441                 if ( $conds != '*' ) {
2442                         if ( is_array( $conds ) ) {
2443                                 $conds = $this->makeList( $conds, LIST_AND );
2444                         }
2445                         $sql .= ' WHERE ' . $conds;
2446                 }
2447
2448                 return $this->query( $sql, $fname );
2449         }
2450
2451         public function insertSelect(
2452                 $destTable, $srcTable, $varMap, $conds,
2453                 $fname = __METHOD__, $insertOptions = [], $selectOptions = []
2454         ) {
2455                 if ( $this->cliMode ) {
2456                         // For massive migrations with downtime, we don't want to select everything
2457                         // into memory and OOM, so do all this native on the server side if possible.
2458                         return $this->nativeInsertSelect(
2459                                 $destTable,
2460                                 $srcTable,
2461                                 $varMap,
2462                                 $conds,
2463                                 $fname,
2464                                 $insertOptions,
2465                                 $selectOptions
2466                         );
2467                 }
2468
2469                 // For web requests, do a locking SELECT and then INSERT. This puts the SELECT burden
2470                 // on only the master (without needing row-based-replication). It also makes it easy to
2471                 // know how big the INSERT is going to be.
2472                 $fields = [];
2473                 foreach ( $varMap as $dstColumn => $sourceColumnOrSql ) {
2474                         $fields[] = $this->fieldNameWithAlias( $sourceColumnOrSql, $dstColumn );
2475                 }
2476                 $selectOptions[] = 'FOR UPDATE';
2477                 $res = $this->select( $srcTable, implode( ',', $fields ), $conds, $fname, $selectOptions );
2478                 if ( !$res ) {
2479                         return false;
2480                 }
2481
2482                 $rows = [];
2483                 foreach ( $res as $row ) {
2484                         $rows[] = (array)$row;
2485                 }
2486
2487                 return $this->insert( $destTable, $rows, $fname, $insertOptions );
2488         }
2489
2490         public function nativeInsertSelect( $destTable, $srcTable, $varMap, $conds,
2491                 $fname = __METHOD__,
2492                 $insertOptions = [], $selectOptions = []
2493         ) {
2494                 $destTable = $this->tableName( $destTable );
2495
2496                 if ( !is_array( $insertOptions ) ) {
2497                         $insertOptions = [ $insertOptions ];
2498                 }
2499
2500                 $insertOptions = $this->makeInsertOptions( $insertOptions );
2501
2502                 if ( !is_array( $selectOptions ) ) {
2503                         $selectOptions = [ $selectOptions ];
2504                 }
2505
2506                 list( $startOpts, $useIndex, $tailOpts, $ignoreIndex ) = $this->makeSelectOptions(
2507                         $selectOptions );
2508
2509                 if ( is_array( $srcTable ) ) {
2510                         $srcTable = implode( ',', array_map( [ &$this, 'tableName' ], $srcTable ) );
2511                 } else {
2512                         $srcTable = $this->tableName( $srcTable );
2513                 }
2514
2515                 $sql = "INSERT $insertOptions INTO $destTable (" . implode( ',', array_keys( $varMap ) ) . ')' .
2516                         " SELECT $startOpts " . implode( ',', $varMap ) .
2517                         " FROM $srcTable $useIndex $ignoreIndex ";
2518
2519                 if ( $conds != '*' ) {
2520                         if ( is_array( $conds ) ) {
2521                                 $conds = $this->makeList( $conds, LIST_AND );
2522                         }
2523                         $sql .= " WHERE $conds";
2524                 }
2525
2526                 $sql .= " $tailOpts";
2527
2528                 return $this->query( $sql, $fname );
2529         }
2530
2531         /**
2532          * Construct a LIMIT query with optional offset. This is used for query
2533          * pages. The SQL should be adjusted so that only the first $limit rows
2534          * are returned. If $offset is provided as well, then the first $offset
2535          * rows should be discarded, and the next $limit rows should be returned.
2536          * If the result of the query is not ordered, then the rows to be returned
2537          * are theoretically arbitrary.
2538          *
2539          * $sql is expected to be a SELECT, if that makes a difference.
2540          *
2541          * The version provided by default works in MySQL and SQLite. It will very
2542          * likely need to be overridden for most other DBMSes.
2543          *
2544          * @param string $sql SQL query we will append the limit too
2545          * @param int $limit The SQL limit
2546          * @param int|bool $offset The SQL offset (default false)
2547          * @throws DBUnexpectedError
2548          * @return string
2549          */
2550         public function limitResult( $sql, $limit, $offset = false ) {
2551                 if ( !is_numeric( $limit ) ) {
2552                         throw new DBUnexpectedError( $this, "Invalid non-numeric limit passed to limitResult()\n" );
2553                 }
2554
2555                 return "$sql LIMIT "
2556                         . ( ( is_numeric( $offset ) && $offset != 0 ) ? "{$offset}," : "" )
2557                         . "{$limit} ";
2558         }
2559
2560         public function unionSupportsOrderAndLimit() {
2561                 return true; // True for almost every DB supported
2562         }
2563
2564         public function unionQueries( $sqls, $all ) {
2565                 $glue = $all ? ') UNION ALL (' : ') UNION (';
2566
2567                 return '(' . implode( $glue, $sqls ) . ')';
2568         }
2569
2570         public function conditional( $cond, $trueVal, $falseVal ) {
2571                 if ( is_array( $cond ) ) {
2572                         $cond = $this->makeList( $cond, LIST_AND );
2573                 }
2574
2575                 return " (CASE WHEN $cond THEN $trueVal ELSE $falseVal END) ";
2576         }
2577
2578         public function strreplace( $orig, $old, $new ) {
2579                 return "REPLACE({$orig}, {$old}, {$new})";
2580         }
2581
2582         public function getServerUptime() {
2583                 return 0;
2584         }
2585
2586         public function wasDeadlock() {
2587                 return false;
2588         }
2589
2590         public function wasLockTimeout() {
2591                 return false;
2592         }
2593
2594         public function wasErrorReissuable() {
2595                 return false;
2596         }
2597
2598         public function wasReadOnlyError() {
2599                 return false;
2600         }
2601
2602         /**
2603          * Determines if the given query error was a connection drop
2604          * STUB
2605          *
2606          * @param integer|string $errno
2607          * @return bool
2608          */
2609         public function wasConnectionError( $errno ) {
2610                 return false;
2611         }
2612
2613         /**
2614          * Perform a deadlock-prone transaction.
2615          *
2616          * This function invokes a callback function to perform a set of write
2617          * queries. If a deadlock occurs during the processing, the transaction
2618          * will be rolled back and the callback function will be called again.
2619          *
2620          * Avoid using this method outside of Job or Maintenance classes.
2621          *
2622          * Usage:
2623          *   $dbw->deadlockLoop( callback, ... );
2624          *
2625          * Extra arguments are passed through to the specified callback function.
2626          * This method requires that no transactions are already active to avoid
2627          * causing premature commits or exceptions.
2628          *
2629          * Returns whatever the callback function returned on its successful,
2630          * iteration, or false on error, for example if the retry limit was
2631          * reached.
2632          *
2633          * @return mixed
2634          * @throws DBUnexpectedError
2635          * @throws Exception
2636          */
2637         public function deadlockLoop() {
2638                 $args = func_get_args();
2639                 $function = array_shift( $args );
2640                 $tries = self::DEADLOCK_TRIES;
2641
2642                 $this->begin( __METHOD__ );
2643
2644                 $retVal = null;
2645                 /** @var Exception $e */
2646                 $e = null;
2647                 do {
2648                         try {
2649                                 $retVal = call_user_func_array( $function, $args );
2650                                 break;
2651                         } catch ( DBQueryError $e ) {
2652                                 if ( $this->wasDeadlock() ) {
2653                                         // Retry after a randomized delay
2654                                         usleep( mt_rand( self::DEADLOCK_DELAY_MIN, self::DEADLOCK_DELAY_MAX ) );
2655                                 } else {
2656                                         // Throw the error back up
2657                                         throw $e;
2658                                 }
2659                         }
2660                 } while ( --$tries > 0 );
2661
2662                 if ( $tries <= 0 ) {
2663                         // Too many deadlocks; give up
2664                         $this->rollback( __METHOD__ );
2665                         throw $e;
2666                 } else {
2667                         $this->commit( __METHOD__ );
2668
2669                         return $retVal;
2670                 }
2671         }
2672
2673         public function masterPosWait( DBMasterPos $pos, $timeout ) {
2674                 # Real waits are implemented in the subclass.
2675                 return 0;
2676         }
2677
2678         public function getSlavePos() {
2679                 # Stub
2680                 return false;
2681         }
2682
2683         public function getMasterPos() {
2684                 # Stub
2685                 return false;
2686         }
2687
2688         public function serverIsReadOnly() {
2689                 return false;
2690         }
2691
2692         final public function onTransactionResolution( callable $callback, $fname = __METHOD__ ) {
2693                 if ( !$this->mTrxLevel ) {
2694                         throw new DBUnexpectedError( $this, "No transaction is active." );
2695                 }
2696                 $this->mTrxEndCallbacks[] = [ $callback, $fname ];
2697         }
2698
2699         final public function onTransactionIdle( callable $callback, $fname = __METHOD__ ) {
2700                 $this->mTrxIdleCallbacks[] = [ $callback, $fname ];
2701                 if ( !$this->mTrxLevel ) {
2702                         $this->runOnTransactionIdleCallbacks( self::TRIGGER_IDLE );
2703                 }
2704         }
2705
2706         final public function onTransactionPreCommitOrIdle( callable $callback, $fname = __METHOD__ ) {
2707                 if ( $this->mTrxLevel ) {
2708                         $this->mTrxPreCommitCallbacks[] = [ $callback, $fname ];
2709                 } else {
2710                         // If no transaction is active, then make one for this callback
2711                         $this->startAtomic( __METHOD__ );
2712                         try {
2713                                 call_user_func( $callback );
2714                                 $this->endAtomic( __METHOD__ );
2715                         } catch ( Exception $e ) {
2716                                 $this->rollback( __METHOD__, self::FLUSHING_INTERNAL );
2717                                 throw $e;
2718                         }
2719                 }
2720         }
2721
2722         final public function setTransactionListener( $name, callable $callback = null ) {
2723                 if ( $callback ) {
2724                         $this->mTrxRecurringCallbacks[$name] = $callback;
2725                 } else {
2726                         unset( $this->mTrxRecurringCallbacks[$name] );
2727                 }
2728         }
2729
2730         /**
2731          * Whether to disable running of post-COMMIT/ROLLBACK callbacks
2732          *
2733          * This method should not be used outside of Database/LoadBalancer
2734          *
2735          * @param bool $suppress
2736          * @since 1.28
2737          */
2738         final public function setTrxEndCallbackSuppression( $suppress ) {
2739                 $this->mTrxEndCallbacksSuppressed = $suppress;
2740         }
2741
2742         /**
2743          * Actually run and consume any "on transaction idle/resolution" callbacks.
2744          *
2745          * This method should not be used outside of Database/LoadBalancer
2746          *
2747          * @param integer $trigger IDatabase::TRIGGER_* constant
2748          * @since 1.20
2749          * @throws Exception
2750          */
2751         public function runOnTransactionIdleCallbacks( $trigger ) {
2752                 if ( $this->mTrxEndCallbacksSuppressed ) {
2753                         return;
2754                 }
2755
2756                 $autoTrx = $this->getFlag( DBO_TRX ); // automatic begin() enabled?
2757                 /** @var Exception $e */
2758                 $e = null; // first exception
2759                 do { // callbacks may add callbacks :)
2760                         $callbacks = array_merge(
2761                                 $this->mTrxIdleCallbacks,
2762                                 $this->mTrxEndCallbacks // include "transaction resolution" callbacks
2763                         );
2764                         $this->mTrxIdleCallbacks = []; // consumed (and recursion guard)
2765                         $this->mTrxEndCallbacks = []; // consumed (recursion guard)
2766                         foreach ( $callbacks as $callback ) {
2767                                 try {
2768                                         list( $phpCallback ) = $callback;
2769                                         $this->clearFlag( DBO_TRX ); // make each query its own transaction
2770                                         call_user_func_array( $phpCallback, [ $trigger ] );
2771                                         if ( $autoTrx ) {
2772                                                 $this->setFlag( DBO_TRX ); // restore automatic begin()
2773                                         } else {
2774                                                 $this->clearFlag( DBO_TRX ); // restore auto-commit
2775                                         }
2776                                 } catch ( Exception $ex ) {
2777                                         call_user_func( $this->errorLogger, $ex );
2778                                         $e = $e ?: $ex;
2779                                         // Some callbacks may use startAtomic/endAtomic, so make sure
2780                                         // their transactions are ended so other callbacks don't fail
2781                                         if ( $this->trxLevel() ) {
2782                                                 $this->rollback( __METHOD__, self::FLUSHING_INTERNAL );
2783                                         }
2784                                 }
2785                         }
2786                 } while ( count( $this->mTrxIdleCallbacks ) );
2787
2788                 if ( $e instanceof Exception ) {
2789                         throw $e; // re-throw any first exception
2790                 }
2791         }
2792
2793         /**
2794          * Actually run and consume any "on transaction pre-commit" callbacks.
2795          *
2796          * This method should not be used outside of Database/LoadBalancer
2797          *
2798          * @since 1.22
2799          * @throws Exception
2800          */
2801         public function runOnTransactionPreCommitCallbacks() {
2802                 $e = null; // first exception
2803                 do { // callbacks may add callbacks :)
2804                         $callbacks = $this->mTrxPreCommitCallbacks;
2805                         $this->mTrxPreCommitCallbacks = []; // consumed (and recursion guard)
2806                         foreach ( $callbacks as $callback ) {
2807                                 try {
2808                                         list( $phpCallback ) = $callback;
2809                                         call_user_func( $phpCallback );
2810                                 } catch ( Exception $ex ) {
2811                                         call_user_func( $this->errorLogger, $ex );
2812                                         $e = $e ?: $ex;
2813                                 }
2814                         }
2815                 } while ( count( $this->mTrxPreCommitCallbacks ) );
2816
2817                 if ( $e instanceof Exception ) {
2818                         throw $e; // re-throw any first exception
2819                 }
2820         }
2821
2822         /**
2823          * Actually run any "transaction listener" callbacks.
2824          *
2825          * This method should not be used outside of Database/LoadBalancer
2826          *
2827          * @param integer $trigger IDatabase::TRIGGER_* constant
2828          * @throws Exception
2829          * @since 1.20
2830          */
2831         public function runTransactionListenerCallbacks( $trigger ) {
2832                 if ( $this->mTrxEndCallbacksSuppressed ) {
2833                         return;
2834                 }
2835
2836                 /** @var Exception $e */
2837                 $e = null; // first exception
2838
2839                 foreach ( $this->mTrxRecurringCallbacks as $phpCallback ) {
2840                         try {
2841                                 $phpCallback( $trigger, $this );
2842                         } catch ( Exception $ex ) {
2843                                 call_user_func( $this->errorLogger, $ex );
2844                                 $e = $e ?: $ex;
2845                         }
2846                 }
2847
2848                 if ( $e instanceof Exception ) {
2849                         throw $e; // re-throw any first exception
2850                 }
2851         }
2852
2853         final public function startAtomic( $fname = __METHOD__ ) {
2854                 if ( !$this->mTrxLevel ) {
2855                         $this->begin( $fname, self::TRANSACTION_INTERNAL );
2856                         // If DBO_TRX is set, a series of startAtomic/endAtomic pairs will result
2857                         // in all changes being in one transaction to keep requests transactional.
2858                         if ( !$this->getFlag( DBO_TRX ) ) {
2859                                 $this->mTrxAutomaticAtomic = true;
2860                         }
2861                 }
2862
2863                 $this->mTrxAtomicLevels[] = $fname;
2864         }
2865
2866         final public function endAtomic( $fname = __METHOD__ ) {
2867                 if ( !$this->mTrxLevel ) {
2868                         throw new DBUnexpectedError( $this, "No atomic transaction is open (got $fname)." );
2869                 }
2870                 if ( !$this->mTrxAtomicLevels ||
2871                         array_pop( $this->mTrxAtomicLevels ) !== $fname
2872                 ) {
2873                         throw new DBUnexpectedError( $this, "Invalid atomic section ended (got $fname)." );
2874                 }
2875
2876                 if ( !$this->mTrxAtomicLevels && $this->mTrxAutomaticAtomic ) {
2877                         $this->commit( $fname, self::FLUSHING_INTERNAL );
2878                 }
2879         }
2880
2881         final public function doAtomicSection( $fname, callable $callback ) {
2882                 $this->startAtomic( $fname );
2883                 try {
2884                         $res = call_user_func_array( $callback, [ $this, $fname ] );
2885                 } catch ( Exception $e ) {
2886                         $this->rollback( $fname, self::FLUSHING_INTERNAL );
2887                         throw $e;
2888                 }
2889                 $this->endAtomic( $fname );
2890
2891                 return $res;
2892         }
2893
2894         final public function begin( $fname = __METHOD__, $mode = self::TRANSACTION_EXPLICIT ) {
2895                 // Protect against mismatched atomic section, transaction nesting, and snapshot loss
2896                 if ( $this->mTrxLevel ) {
2897                         if ( $this->mTrxAtomicLevels ) {
2898                                 $levels = implode( ', ', $this->mTrxAtomicLevels );
2899                                 $msg = "$fname: Got explicit BEGIN while atomic section(s) $levels are open.";
2900                                 throw new DBUnexpectedError( $this, $msg );
2901                         } elseif ( !$this->mTrxAutomatic ) {
2902                                 $msg = "$fname: Explicit transaction already active (from {$this->mTrxFname}).";
2903                                 throw new DBUnexpectedError( $this, $msg );
2904                         } else {
2905                                 // @TODO: make this an exception at some point
2906                                 $msg = "$fname: Implicit transaction already active (from {$this->mTrxFname}).";
2907                                 $this->queryLogger->error( $msg );
2908                                 return; // join the main transaction set
2909                         }
2910                 } elseif ( $this->getFlag( DBO_TRX ) && $mode !== self::TRANSACTION_INTERNAL ) {
2911                         // @TODO: make this an exception at some point
2912                         $msg = "$fname: Implicit transaction expected (DBO_TRX set).";
2913                         $this->queryLogger->error( $msg );
2914                         return; // let any writes be in the main transaction
2915                 }
2916
2917                 // Avoid fatals if close() was called
2918                 $this->assertOpen();
2919
2920                 $this->doBegin( $fname );
2921                 $this->mTrxTimestamp = microtime( true );
2922                 $this->mTrxFname = $fname;
2923                 $this->mTrxDoneWrites = false;
2924                 $this->mTrxAutomatic = ( $mode === self::TRANSACTION_INTERNAL );
2925                 $this->mTrxAutomaticAtomic = false;
2926                 $this->mTrxAtomicLevels = [];
2927                 $this->mTrxShortId = sprintf( '%06x', mt_rand( 0, 0xffffff ) );
2928                 $this->mTrxWriteDuration = 0.0;
2929                 $this->mTrxWriteQueryCount = 0;
2930                 $this->mTrxWriteAdjDuration = 0.0;
2931                 $this->mTrxWriteAdjQueryCount = 0;
2932                 $this->mTrxWriteCallers = [];
2933                 // First SELECT after BEGIN will establish the snapshot in REPEATABLE-READ.
2934                 // Get an estimate of the replica DB lag before then, treating estimate staleness
2935                 // as lag itself just to be safe
2936                 $status = $this->getApproximateLagStatus();
2937                 $this->mTrxReplicaLag = $status['lag'] + ( microtime( true ) - $status['since'] );
2938         }
2939
2940         /**
2941          * Issues the BEGIN command to the database server.
2942          *
2943          * @see DatabaseBase::begin()
2944          * @param string $fname
2945          */
2946         protected function doBegin( $fname ) {
2947                 $this->query( 'BEGIN', $fname );
2948                 $this->mTrxLevel = 1;
2949         }
2950
2951         final public function commit( $fname = __METHOD__, $flush = '' ) {
2952                 if ( $this->mTrxLevel && $this->mTrxAtomicLevels ) {
2953                         // There are still atomic sections open. This cannot be ignored
2954                         $levels = implode( ', ', $this->mTrxAtomicLevels );
2955                         throw new DBUnexpectedError(
2956                                 $this,
2957                                 "$fname: Got COMMIT while atomic sections $levels are still open."
2958                         );
2959                 }
2960
2961                 if ( $flush === self::FLUSHING_INTERNAL || $flush === self::FLUSHING_ALL_PEERS ) {
2962                         if ( !$this->mTrxLevel ) {
2963                                 return; // nothing to do
2964                         } elseif ( !$this->mTrxAutomatic ) {
2965                                 throw new DBUnexpectedError(
2966                                         $this,
2967                                         "$fname: Flushing an explicit transaction, getting out of sync."
2968                                 );
2969                         }
2970                 } else {
2971                         if ( !$this->mTrxLevel ) {
2972                                 $this->queryLogger->error( "$fname: No transaction to commit, something got out of sync." );
2973                                 return; // nothing to do
2974                         } elseif ( $this->mTrxAutomatic ) {
2975                                 // @TODO: make this an exception at some point
2976                                 $msg = "$fname: Explicit commit of implicit transaction.";
2977                                 $this->queryLogger->error( $msg );
2978                                 return; // wait for the main transaction set commit round
2979                         }
2980                 }
2981
2982                 // Avoid fatals if close() was called
2983                 $this->assertOpen();
2984
2985                 $this->runOnTransactionPreCommitCallbacks();
2986                 $writeTime = $this->pendingWriteQueryDuration( self::ESTIMATE_DB_APPLY );
2987                 $this->doCommit( $fname );
2988                 if ( $this->mTrxDoneWrites ) {
2989                         $this->mDoneWrites = microtime( true );
2990                         $this->trxProfiler->transactionWritingOut(
2991                                 $this->mServer, $this->mDBname, $this->mTrxShortId, $writeTime );
2992                 }
2993
2994                 $this->runOnTransactionIdleCallbacks( self::TRIGGER_COMMIT );
2995                 $this->runTransactionListenerCallbacks( self::TRIGGER_COMMIT );
2996         }
2997
2998         /**
2999          * Issues the COMMIT command to the database server.
3000          *
3001          * @see DatabaseBase::commit()
3002          * @param string $fname
3003          */
3004         protected function doCommit( $fname ) {
3005                 if ( $this->mTrxLevel ) {
3006                         $this->query( 'COMMIT', $fname );
3007                         $this->mTrxLevel = 0;
3008                 }
3009         }
3010
3011         final public function rollback( $fname = __METHOD__, $flush = '' ) {
3012                 if ( $flush === self::FLUSHING_INTERNAL || $flush === self::FLUSHING_ALL_PEERS ) {
3013                         if ( !$this->mTrxLevel ) {
3014                                 return; // nothing to do
3015                         }
3016                 } else {
3017                         if ( !$this->mTrxLevel ) {
3018                                 $this->queryLogger->error(
3019                                         "$fname: No transaction to rollback, something got out of sync." );
3020                                 return; // nothing to do
3021                         } elseif ( $this->getFlag( DBO_TRX ) ) {
3022                                 throw new DBUnexpectedError(
3023                                         $this,
3024                                         "$fname: Expected mass rollback of all peer databases (DBO_TRX set)."
3025                                 );
3026                         }
3027                 }
3028
3029                 // Avoid fatals if close() was called
3030                 $this->assertOpen();
3031
3032                 $this->doRollback( $fname );
3033                 $this->mTrxAtomicLevels = [];
3034                 if ( $this->mTrxDoneWrites ) {
3035                         $this->trxProfiler->transactionWritingOut(
3036                                 $this->mServer, $this->mDBname, $this->mTrxShortId );
3037                 }
3038
3039                 $this->mTrxIdleCallbacks = []; // clear
3040                 $this->mTrxPreCommitCallbacks = []; // clear
3041                 $this->runOnTransactionIdleCallbacks( self::TRIGGER_ROLLBACK );
3042                 $this->runTransactionListenerCallbacks( self::TRIGGER_ROLLBACK );
3043         }
3044
3045         /**
3046          * Issues the ROLLBACK command to the database server.
3047          *
3048          * @see DatabaseBase::rollback()
3049          * @param string $fname
3050          */
3051         protected function doRollback( $fname ) {
3052                 if ( $this->mTrxLevel ) {
3053                         # Disconnects cause rollback anyway, so ignore those errors
3054                         $ignoreErrors = true;
3055                         $this->query( 'ROLLBACK', $fname, $ignoreErrors );
3056                         $this->mTrxLevel = 0;
3057                 }
3058         }
3059
3060         public function flushSnapshot( $fname = __METHOD__ ) {
3061                 if ( $this->writesOrCallbacksPending() || $this->explicitTrxActive() ) {
3062                         // This only flushes transactions to clear snapshots, not to write data
3063                         throw new DBUnexpectedError(
3064                                 $this,
3065                                 "$fname: Cannot COMMIT to clear snapshot because writes are pending."
3066                         );
3067                 }
3068
3069                 $this->commit( $fname, self::FLUSHING_INTERNAL );
3070         }
3071
3072         public function explicitTrxActive() {
3073                 return $this->mTrxLevel && ( $this->mTrxAtomicLevels || !$this->mTrxAutomatic );
3074         }
3075
3076         /**
3077          * Creates a new table with structure copied from existing table
3078          * Note that unlike most database abstraction functions, this function does not
3079          * automatically append database prefix, because it works at a lower
3080          * abstraction level.
3081          * The table names passed to this function shall not be quoted (this
3082          * function calls addIdentifierQuotes when needed).
3083          *
3084          * @param string $oldName Name of table whose structure should be copied
3085          * @param string $newName Name of table to be created
3086          * @param bool $temporary Whether the new table should be temporary
3087          * @param string $fname Calling function name
3088          * @throws RuntimeException
3089          * @return bool True if operation was successful
3090          */
3091         public function duplicateTableStructure( $oldName, $newName, $temporary = false,
3092                 $fname = __METHOD__
3093         ) {
3094                 throw new RuntimeException( __METHOD__ . ' is not implemented in descendant class' );
3095         }
3096
3097         function listTables( $prefix = null, $fname = __METHOD__ ) {
3098                 throw new RuntimeException( __METHOD__ . ' is not implemented in descendant class' );
3099         }
3100
3101         /**
3102          * Reset the views process cache set by listViews()
3103          * @since 1.22
3104          */
3105         final public function clearViewsCache() {
3106                 $this->allViews = null;
3107         }
3108
3109         /**
3110          * Lists all the VIEWs in the database
3111          *
3112          * For caching purposes the list of all views should be stored in
3113          * $this->allViews. The process cache can be cleared with clearViewsCache()
3114          *
3115          * @param string $prefix Only show VIEWs with this prefix, eg. unit_test_
3116          * @param string $fname Name of calling function
3117          * @throws RuntimeException
3118          * @return array
3119          * @since 1.22
3120          */
3121         public function listViews( $prefix = null, $fname = __METHOD__ ) {
3122                 throw new RuntimeException( __METHOD__ . ' is not implemented in descendant class' );
3123         }
3124
3125         /**
3126          * Differentiates between a TABLE and a VIEW
3127          *
3128          * @param string $name Name of the database-structure to test.
3129          * @throws RuntimeException
3130          * @return bool
3131          * @since 1.22
3132          */
3133         public function isView( $name ) {
3134                 throw new RuntimeException( __METHOD__ . ' is not implemented in descendant class' );
3135         }
3136
3137         public function timestamp( $ts = 0 ) {
3138                 return wfTimestamp( TS_MW, $ts );
3139         }
3140
3141         public function timestampOrNull( $ts = null ) {
3142                 if ( is_null( $ts ) ) {
3143                         return null;
3144                 } else {
3145                         return $this->timestamp( $ts );
3146                 }
3147         }
3148
3149         /**
3150          * Take the result from a query, and wrap it in a ResultWrapper if
3151          * necessary. Boolean values are passed through as is, to indicate success
3152          * of write queries or failure.
3153          *
3154          * Once upon a time, DatabaseBase::query() returned a bare MySQL result
3155          * resource, and it was necessary to call this function to convert it to
3156          * a wrapper. Nowadays, raw database objects are never exposed to external
3157          * callers, so this is unnecessary in external code.
3158          *
3159          * @param bool|ResultWrapper|resource|object $result
3160          * @return bool|ResultWrapper
3161          */
3162         protected function resultObject( $result ) {
3163                 if ( !$result ) {
3164                         return false;
3165                 } elseif ( $result instanceof ResultWrapper ) {
3166                         return $result;
3167                 } elseif ( $result === true ) {
3168                         // Successful write query
3169                         return $result;
3170                 } else {
3171                         return new ResultWrapper( $this, $result );
3172                 }
3173         }
3174
3175         public function ping( &$rtt = null ) {
3176                 // Avoid hitting the server if it was hit recently
3177                 if ( $this->isOpen() && ( microtime( true ) - $this->lastPing ) < self::PING_TTL ) {
3178                         if ( !func_num_args() || $this->mRTTEstimate > 0 ) {
3179                                 $rtt = $this->mRTTEstimate;
3180                                 return true; // don't care about $rtt
3181                         }
3182                 }
3183
3184                 // This will reconnect if possible or return false if not
3185                 $this->clearFlag( DBO_TRX, self::REMEMBER_PRIOR );
3186                 $ok = ( $this->query( self::PING_QUERY, __METHOD__, true ) !== false );
3187                 $this->restoreFlags( self::RESTORE_PRIOR );
3188
3189                 if ( $ok ) {
3190                         $rtt = $this->mRTTEstimate;
3191                 }
3192
3193                 return $ok;
3194         }
3195
3196         /**
3197          * @return bool
3198          */
3199         protected function reconnect() {
3200                 $this->closeConnection();
3201                 $this->mOpened = false;
3202                 $this->mConn = false;
3203                 try {
3204                         $this->open( $this->mServer, $this->mUser, $this->mPassword, $this->mDBname );
3205                         $this->lastPing = microtime( true );
3206                         $ok = true;
3207                 } catch ( DBConnectionError $e ) {
3208                         $ok = false;
3209                 }
3210
3211                 return $ok;
3212         }
3213
3214         public function getSessionLagStatus() {
3215                 return $this->getTransactionLagStatus() ?: $this->getApproximateLagStatus();
3216         }
3217
3218         /**
3219          * Get the replica DB lag when the current transaction started
3220          *
3221          * This is useful when transactions might use snapshot isolation
3222          * (e.g. REPEATABLE-READ in innodb), so the "real" lag of that data
3223          * is this lag plus transaction duration. If they don't, it is still
3224          * safe to be pessimistic. This returns null if there is no transaction.
3225          *
3226          * @return array|null ('lag': seconds or false on error, 'since': UNIX timestamp of BEGIN)
3227          * @since 1.27
3228          */
3229         public function getTransactionLagStatus() {
3230                 return $this->mTrxLevel
3231                         ? [ 'lag' => $this->mTrxReplicaLag, 'since' => $this->trxTimestamp() ]
3232                         : null;
3233         }
3234
3235         /**
3236          * Get a replica DB lag estimate for this server
3237          *
3238          * @return array ('lag': seconds or false on error, 'since': UNIX timestamp of estimate)
3239          * @since 1.27
3240          */
3241         public function getApproximateLagStatus() {
3242                 return [
3243                         'lag'   => $this->getLBInfo( 'replica' ) ? $this->getLag() : 0,
3244                         'since' => microtime( true )
3245                 ];
3246         }
3247
3248         /**
3249          * Merge the result of getSessionLagStatus() for several DBs
3250          * using the most pessimistic values to estimate the lag of
3251          * any data derived from them in combination
3252          *
3253          * This is information is useful for caching modules
3254          *
3255          * @see WANObjectCache::set()
3256          * @see WANObjectCache::getWithSetCallback()
3257          *
3258          * @param IDatabase $db1
3259          * @param IDatabase ...
3260          * @return array Map of values:
3261          *   - lag: highest lag of any of the DBs or false on error (e.g. replication stopped)
3262          *   - since: oldest UNIX timestamp of any of the DB lag estimates
3263          *   - pending: whether any of the DBs have uncommitted changes
3264          * @since 1.27
3265          */
3266         public static function getCacheSetOptions( IDatabase $db1 ) {
3267                 $res = [ 'lag' => 0, 'since' => INF, 'pending' => false ];
3268                 foreach ( func_get_args() as $db ) {
3269                         /** @var IDatabase $db */
3270                         $status = $db->getSessionLagStatus();
3271                         if ( $status['lag'] === false ) {
3272                                 $res['lag'] = false;
3273                         } elseif ( $res['lag'] !== false ) {
3274                                 $res['lag'] = max( $res['lag'], $status['lag'] );
3275                         }
3276                         $res['since'] = min( $res['since'], $status['since'] );
3277                         $res['pending'] = $res['pending'] ?: $db->writesPending();
3278                 }
3279
3280                 return $res;
3281         }
3282
3283         public function getLag() {
3284                 return 0;
3285         }
3286
3287         function maxListLen() {
3288                 return 0;
3289         }
3290
3291         public function encodeBlob( $b ) {
3292                 return $b;
3293         }
3294
3295         public function decodeBlob( $b ) {
3296                 if ( $b instanceof Blob ) {
3297                         $b = $b->fetch();
3298                 }
3299                 return $b;
3300         }
3301
3302         public function setSessionOptions( array $options ) {
3303         }
3304
3305         /**
3306          * Read and execute SQL commands from a file.
3307          *
3308          * Returns true on success, error string or exception on failure (depending
3309          * on object's error ignore settings).
3310          *
3311          * @param string $filename File name to open
3312          * @param bool|callable $lineCallback Optional function called before reading each line
3313          * @param bool|callable $resultCallback Optional function called for each MySQL result
3314          * @param bool|string $fname Calling function name or false if name should be
3315          *   generated dynamically using $filename
3316          * @param bool|callable $inputCallback Optional function called for each
3317          *   complete line sent
3318          * @return bool|string
3319          * @throws Exception
3320          */
3321         public function sourceFile(
3322                 $filename, $lineCallback = false, $resultCallback = false, $fname = false, $inputCallback = false
3323         ) {
3324                 MediaWiki\suppressWarnings();
3325                 $fp = fopen( $filename, 'r' );
3326                 MediaWiki\restoreWarnings();
3327
3328                 if ( false === $fp ) {
3329                         throw new RuntimeException( "Could not open \"{$filename}\".\n" );
3330                 }
3331
3332                 if ( !$fname ) {
3333                         $fname = __METHOD__ . "( $filename )";
3334                 }
3335
3336                 try {
3337                         $error = $this->sourceStream( $fp, $lineCallback, $resultCallback, $fname, $inputCallback );
3338                 } catch ( Exception $e ) {
3339                         fclose( $fp );
3340                         throw $e;
3341                 }
3342
3343                 fclose( $fp );
3344
3345                 return $error;
3346         }
3347
3348         public function setSchemaVars( $vars ) {
3349                 $this->mSchemaVars = $vars;
3350         }
3351
3352         /**
3353          * Read and execute commands from an open file handle.
3354          *
3355          * Returns true on success, error string or exception on failure (depending
3356          * on object's error ignore settings).
3357          *
3358          * @param resource $fp File handle
3359          * @param bool|callable $lineCallback Optional function called before reading each query
3360          * @param bool|callable $resultCallback Optional function called for each MySQL result
3361          * @param string $fname Calling function name
3362          * @param bool|callable $inputCallback Optional function called for each complete query sent
3363          * @return bool|string
3364          */
3365         public function sourceStream( $fp, $lineCallback = false, $resultCallback = false,
3366                 $fname = __METHOD__, $inputCallback = false
3367         ) {
3368                 $cmd = '';
3369
3370                 while ( !feof( $fp ) ) {
3371                         if ( $lineCallback ) {
3372                                 call_user_func( $lineCallback );
3373                         }
3374
3375                         $line = trim( fgets( $fp ) );
3376
3377                         if ( $line == '' ) {
3378                                 continue;
3379                         }
3380
3381                         if ( '-' == $line[0] && '-' == $line[1] ) {
3382                                 continue;
3383                         }
3384
3385                         if ( $cmd != '' ) {
3386                                 $cmd .= ' ';
3387                         }
3388
3389                         $done = $this->streamStatementEnd( $cmd, $line );
3390
3391                         $cmd .= "$line\n";
3392
3393                         if ( $done || feof( $fp ) ) {
3394                                 $cmd = $this->replaceVars( $cmd );
3395
3396                                 if ( ( $inputCallback && call_user_func( $inputCallback, $cmd ) ) || !$inputCallback ) {
3397                                         $res = $this->query( $cmd, $fname );
3398
3399                                         if ( $resultCallback ) {
3400                                                 call_user_func( $resultCallback, $res, $this );
3401                                         }
3402
3403                                         if ( false === $res ) {
3404                                                 $err = $this->lastError();
3405
3406                                                 return "Query \"{$cmd}\" failed with error code \"$err\".\n";
3407                                         }
3408                                 }
3409                                 $cmd = '';
3410                         }
3411                 }
3412
3413                 return true;
3414         }
3415
3416         /**
3417          * Called by sourceStream() to check if we've reached a statement end
3418          *
3419          * @param string $sql SQL assembled so far
3420          * @param string $newLine New line about to be added to $sql
3421          * @return bool Whether $newLine contains end of the statement
3422          */
3423         public function streamStatementEnd( &$sql, &$newLine ) {
3424                 if ( $this->delimiter ) {
3425                         $prev = $newLine;
3426                         $newLine = preg_replace( '/' . preg_quote( $this->delimiter, '/' ) . '$/', '', $newLine );
3427                         if ( $newLine != $prev ) {
3428                                 return true;
3429                         }
3430                 }
3431
3432                 return false;
3433         }
3434
3435         /**
3436          * Database independent variable replacement. Replaces a set of variables
3437          * in an SQL statement with their contents as given by $this->getSchemaVars().
3438          *
3439          * Supports '{$var}' `{$var}` and / *$var* / (without the spaces) style variables.
3440          *
3441          * - '{$var}' should be used for text and is passed through the database's
3442          *   addQuotes method.
3443          * - `{$var}` should be used for identifiers (e.g. table and database names).
3444          *   It is passed through the database's addIdentifierQuotes method which
3445          *   can be overridden if the database uses something other than backticks.
3446          * - / *_* / or / *$wgDBprefix* / passes the name that follows through the
3447          *   database's tableName method.
3448          * - / *i* / passes the name that follows through the database's indexName method.
3449          * - In all other cases, / *$var* / is left unencoded. Except for table options,
3450          *   its use should be avoided. In 1.24 and older, string encoding was applied.
3451          *
3452          * @param string $ins SQL statement to replace variables in
3453          * @return string The new SQL statement with variables replaced
3454          */
3455         protected function replaceVars( $ins ) {
3456                 $vars = $this->getSchemaVars();
3457                 return preg_replace_callback(
3458                         '!
3459                                 /\* (\$wgDBprefix|[_i]) \*/ (\w*) | # 1-2. tableName, indexName
3460                                 \'\{\$ (\w+) }\'                  | # 3. addQuotes
3461                                 `\{\$ (\w+) }`                    | # 4. addIdentifierQuotes
3462                                 /\*\$ (\w+) \*/                     # 5. leave unencoded
3463                         !x',
3464                         function ( $m ) use ( $vars ) {
3465                                 // Note: Because of <https://bugs.php.net/bug.php?id=51881>,
3466                                 // check for both nonexistent keys *and* the empty string.
3467                                 if ( isset( $m[1] ) && $m[1] !== '' ) {
3468                                         if ( $m[1] === 'i' ) {
3469                                                 return $this->indexName( $m[2] );
3470                                         } else {
3471                                                 return $this->tableName( $m[2] );
3472                                         }
3473                                 } elseif ( isset( $m[3] ) && $m[3] !== '' && array_key_exists( $m[3], $vars ) ) {
3474                                         return $this->addQuotes( $vars[$m[3]] );
3475                                 } elseif ( isset( $m[4] ) && $m[4] !== '' && array_key_exists( $m[4], $vars ) ) {
3476                                         return $this->addIdentifierQuotes( $vars[$m[4]] );
3477                                 } elseif ( isset( $m[5] ) && $m[5] !== '' && array_key_exists( $m[5], $vars ) ) {
3478                                         return $vars[$m[5]];
3479                                 } else {
3480                                         return $m[0];
3481                                 }
3482                         },
3483                         $ins
3484                 );
3485         }
3486
3487         /**
3488          * Get schema variables. If none have been set via setSchemaVars(), then
3489          * use some defaults from the current object.
3490          *
3491          * @return array
3492          */
3493         protected function getSchemaVars() {
3494                 if ( $this->mSchemaVars ) {
3495                         return $this->mSchemaVars;
3496                 } else {
3497                         return $this->getDefaultSchemaVars();
3498                 }
3499         }
3500
3501         /**
3502          * Get schema variables to use if none have been set via setSchemaVars().
3503          *
3504          * Override this in derived classes to provide variables for tables.sql
3505          * and SQL patch files.
3506          *
3507          * @return array
3508          */
3509         protected function getDefaultSchemaVars() {
3510                 return [];
3511         }
3512
3513         public function lockIsFree( $lockName, $method ) {
3514                 return true;
3515         }
3516
3517         public function lock( $lockName, $method, $timeout = 5 ) {
3518                 $this->mNamedLocksHeld[$lockName] = 1;
3519
3520                 return true;
3521         }
3522
3523         public function unlock( $lockName, $method ) {
3524                 unset( $this->mNamedLocksHeld[$lockName] );
3525
3526                 return true;
3527         }
3528
3529         public function getScopedLockAndFlush( $lockKey, $fname, $timeout ) {
3530                 if ( $this->writesOrCallbacksPending() ) {
3531                         // This only flushes transactions to clear snapshots, not to write data
3532                         throw new DBUnexpectedError(
3533                                 $this,
3534                                 "$fname: Cannot COMMIT to clear snapshot because writes are pending."
3535                         );
3536                 }
3537
3538                 if ( !$this->lock( $lockKey, $fname, $timeout ) ) {
3539                         return null;
3540                 }
3541
3542                 $unlocker = new ScopedCallback( function () use ( $lockKey, $fname ) {
3543                         if ( $this->trxLevel() ) {
3544                                 // There is a good chance an exception was thrown, causing any early return
3545                                 // from the caller. Let any error handler get a chance to issue rollback().
3546                                 // If there isn't one, let the error bubble up and trigger server-side rollback.
3547                                 $this->onTransactionResolution(
3548                                         function () use ( $lockKey, $fname ) {
3549                                                 $this->unlock( $lockKey, $fname );
3550                                         },
3551                                         $fname
3552                                 );
3553                         } else {
3554                                 $this->unlock( $lockKey, $fname );
3555                         }
3556                 } );
3557
3558                 $this->commit( $fname, self::FLUSHING_INTERNAL );
3559
3560                 return $unlocker;
3561         }
3562
3563         public function namedLocksEnqueue() {
3564                 return false;
3565         }
3566
3567         /**
3568          * Lock specific tables
3569          *
3570          * @param array $read Array of tables to lock for read access
3571          * @param array $write Array of tables to lock for write access
3572          * @param string $method Name of caller
3573          * @param bool $lowPriority Whether to indicate writes to be LOW PRIORITY
3574          * @return bool
3575          */
3576         public function lockTables( $read, $write, $method, $lowPriority = true ) {
3577                 return true;
3578         }
3579
3580         /**
3581          * Unlock specific tables
3582          *
3583          * @param string $method The caller
3584          * @return bool
3585          */
3586         public function unlockTables( $method ) {
3587                 return true;
3588         }
3589
3590         /**
3591          * Delete a table
3592          * @param string $tableName
3593          * @param string $fName
3594          * @return bool|ResultWrapper
3595          * @since 1.18
3596          */
3597         public function dropTable( $tableName, $fName = __METHOD__ ) {
3598                 if ( !$this->tableExists( $tableName, $fName ) ) {
3599                         return false;
3600                 }
3601                 $sql = "DROP TABLE " . $this->tableName( $tableName );
3602                 if ( $this->cascadingDeletes() ) {
3603                         $sql .= " CASCADE";
3604                 }
3605
3606                 return $this->query( $sql, $fName );
3607         }
3608
3609         /**
3610          * Get search engine class. All subclasses of this need to implement this
3611          * if they wish to use searching.
3612          *
3613          * @return string
3614          */
3615         public function getSearchEngine() {
3616                 return 'SearchEngineDummy';
3617         }
3618
3619         public function getInfinity() {
3620                 return 'infinity';
3621         }
3622
3623         public function encodeExpiry( $expiry ) {
3624                 return ( $expiry == '' || $expiry == 'infinity' || $expiry == $this->getInfinity() )
3625                         ? $this->getInfinity()
3626                         : $this->timestamp( $expiry );
3627         }
3628
3629         public function decodeExpiry( $expiry, $format = TS_MW ) {
3630                 return ( $expiry == '' || $expiry == 'infinity' || $expiry == $this->getInfinity() )
3631                         ? 'infinity'
3632                         : wfTimestamp( $format, $expiry );
3633         }
3634
3635         public function setBigSelects( $value = true ) {
3636                 // no-op
3637         }
3638
3639         public function isReadOnly() {
3640                 return ( $this->getReadOnlyReason() !== false );
3641         }
3642
3643         /**
3644          * @return string|bool Reason this DB is read-only or false if it is not
3645          */
3646         protected function getReadOnlyReason() {
3647                 $reason = $this->getLBInfo( 'readOnlyReason' );
3648
3649                 return is_string( $reason ) ? $reason : false;
3650         }
3651
3652         public function setTableAliases( array $aliases ) {
3653                 $this->tableAliases = $aliases;
3654         }
3655
3656         /**
3657          * @since 1.19
3658          * @return string
3659          */
3660         public function __toString() {
3661                 return (string)$this->mConn;
3662         }
3663
3664         /**
3665          * Run a few simple sanity checks
3666          */
3667         public function __destruct() {
3668                 if ( $this->mTrxLevel && $this->mTrxDoneWrites ) {
3669                         trigger_error( "Uncommitted DB writes (transaction from {$this->mTrxFname})." );
3670                 }
3671                 $danglingCallbacks = array_merge(
3672                         $this->mTrxIdleCallbacks,
3673                         $this->mTrxPreCommitCallbacks,
3674                         $this->mTrxEndCallbacks
3675                 );
3676                 if ( $danglingCallbacks ) {
3677                         $callers = [];
3678                         foreach ( $danglingCallbacks as $callbackInfo ) {
3679                                 $callers[] = $callbackInfo[1];
3680                         }
3681                         $callers = implode( ', ', $callers );
3682                         trigger_error( "DB transaction callbacks still pending (from $callers)." );
3683                 }
3684         }
3685 }
3686
3687 /**
3688  * @since 1.27
3689  */
3690 abstract class Database extends DatabaseBase {
3691         // B/C until nothing type hints for DatabaseBase
3692         // @TODO: finish renaming DatabaseBase => Database
3693 }