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