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