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         public function select( $table, $vars, $conds = '', $fname = __METHOD__,
1234                 $options = [], $join_conds = [] ) {
1235                 $sql = $this->selectSQLText( $table, $vars, $conds, $fname, $options, $join_conds );
1236
1237                 return $this->query( $sql, $fname );
1238         }
1239
1240         public function selectSQLText( $table, $vars, $conds = '', $fname = __METHOD__,
1241                 $options = [], $join_conds = []
1242         ) {
1243                 if ( is_array( $vars ) ) {
1244                         $vars = implode( ',', $this->fieldNamesWithAlias( $vars ) );
1245                 }
1246
1247                 $options = (array)$options;
1248                 $useIndexes = ( isset( $options['USE INDEX'] ) && is_array( $options['USE INDEX'] ) )
1249                         ? $options['USE INDEX']
1250                         : [];
1251                 $ignoreIndexes = (
1252                         isset( $options['IGNORE INDEX'] ) &&
1253                         is_array( $options['IGNORE INDEX'] )
1254                 )
1255                         ? $options['IGNORE INDEX']
1256                         : [];
1257
1258                 if ( is_array( $table ) ) {
1259                         $from = ' FROM ' .
1260                                 $this->tableNamesWithIndexClauseOrJOIN(
1261                                         $table, $useIndexes, $ignoreIndexes, $join_conds );
1262                 } elseif ( $table != '' ) {
1263                         if ( $table[0] == ' ' ) {
1264                                 $from = ' FROM ' . $table;
1265                         } else {
1266                                 $from = ' FROM ' .
1267                                         $this->tableNamesWithIndexClauseOrJOIN(
1268                                                 [ $table ], $useIndexes, $ignoreIndexes, [] );
1269                         }
1270                 } else {
1271                         $from = '';
1272                 }
1273
1274                 list( $startOpts, $useIndex, $preLimitTail, $postLimitTail, $ignoreIndex ) =
1275                         $this->makeSelectOptions( $options );
1276
1277                 if ( !empty( $conds ) ) {
1278                         if ( is_array( $conds ) ) {
1279                                 $conds = $this->makeList( $conds, self::LIST_AND );
1280                         }
1281                         $sql = "SELECT $startOpts $vars $from $useIndex $ignoreIndex " .
1282                                 "WHERE $conds $preLimitTail";
1283                 } else {
1284                         $sql = "SELECT $startOpts $vars $from $useIndex $ignoreIndex $preLimitTail";
1285                 }
1286
1287                 if ( isset( $options['LIMIT'] ) ) {
1288                         $sql = $this->limitResult( $sql, $options['LIMIT'],
1289                                 isset( $options['OFFSET'] ) ? $options['OFFSET'] : false );
1290                 }
1291                 $sql = "$sql $postLimitTail";
1292
1293                 if ( isset( $options['EXPLAIN'] ) ) {
1294                         $sql = 'EXPLAIN ' . $sql;
1295                 }
1296
1297                 return $sql;
1298         }
1299
1300         public function selectRow( $table, $vars, $conds, $fname = __METHOD__,
1301                 $options = [], $join_conds = []
1302         ) {
1303                 $options = (array)$options;
1304                 $options['LIMIT'] = 1;
1305                 $res = $this->select( $table, $vars, $conds, $fname, $options, $join_conds );
1306
1307                 if ( $res === false ) {
1308                         return false;
1309                 }
1310
1311                 if ( !$this->numRows( $res ) ) {
1312                         return false;
1313                 }
1314
1315                 $obj = $this->fetchObject( $res );
1316
1317                 return $obj;
1318         }
1319
1320         public function estimateRowCount(
1321                 $table, $vars = '*', $conds = '', $fname = __METHOD__, $options = []
1322         ) {
1323                 $rows = 0;
1324                 $res = $this->select( $table, [ 'rowcount' => 'COUNT(*)' ], $conds, $fname, $options );
1325
1326                 if ( $res ) {
1327                         $row = $this->fetchRow( $res );
1328                         $rows = ( isset( $row['rowcount'] ) ) ? (int)$row['rowcount'] : 0;
1329                 }
1330
1331                 return $rows;
1332         }
1333
1334         public function selectRowCount(
1335                 $tables, $vars = '*', $conds = '', $fname = __METHOD__, $options = [], $join_conds = []
1336         ) {
1337                 $rows = 0;
1338                 $sql = $this->selectSQLText( $tables, '1', $conds, $fname, $options, $join_conds );
1339                 $res = $this->query( "SELECT COUNT(*) AS rowcount FROM ($sql) tmp_count", $fname );
1340
1341                 if ( $res ) {
1342                         $row = $this->fetchRow( $res );
1343                         $rows = ( isset( $row['rowcount'] ) ) ? (int)$row['rowcount'] : 0;
1344                 }
1345
1346                 return $rows;
1347         }
1348
1349         /**
1350          * Removes most variables from an SQL query and replaces them with X or N for numbers.
1351          * It's only slightly flawed. Don't use for anything important.
1352          *
1353          * @param string $sql A SQL Query
1354          *
1355          * @return string
1356          */
1357         protected static function generalizeSQL( $sql ) {
1358                 # This does the same as the regexp below would do, but in such a way
1359                 # as to avoid crashing php on some large strings.
1360                 # $sql = preg_replace( "/'([^\\\\']|\\\\.)*'|\"([^\\\\\"]|\\\\.)*\"/", "'X'", $sql );
1361
1362                 $sql = str_replace( "\\\\", '', $sql );
1363                 $sql = str_replace( "\\'", '', $sql );
1364                 $sql = str_replace( "\\\"", '', $sql );
1365                 $sql = preg_replace( "/'.*'/s", "'X'", $sql );
1366                 $sql = preg_replace( '/".*"/s', "'X'", $sql );
1367
1368                 # All newlines, tabs, etc replaced by single space
1369                 $sql = preg_replace( '/\s+/', ' ', $sql );
1370
1371                 # All numbers => N,
1372                 # except the ones surrounded by characters, e.g. l10n
1373                 $sql = preg_replace( '/-?\d+(,-?\d+)+/s', 'N,...,N', $sql );
1374                 $sql = preg_replace( '/(?<![a-zA-Z])-?\d+(?![a-zA-Z])/s', 'N', $sql );
1375
1376                 return $sql;
1377         }
1378
1379         public function fieldExists( $table, $field, $fname = __METHOD__ ) {
1380                 $info = $this->fieldInfo( $table, $field );
1381
1382                 return (bool)$info;
1383         }
1384
1385         public function indexExists( $table, $index, $fname = __METHOD__ ) {
1386                 if ( !$this->tableExists( $table ) ) {
1387                         return null;
1388                 }
1389
1390                 $info = $this->indexInfo( $table, $index, $fname );
1391                 if ( is_null( $info ) ) {
1392                         return null;
1393                 } else {
1394                         return $info !== false;
1395                 }
1396         }
1397
1398         public function tableExists( $table, $fname = __METHOD__ ) {
1399                 $tableRaw = $this->tableName( $table, 'raw' );
1400                 if ( isset( $this->mSessionTempTables[$tableRaw] ) ) {
1401                         return true; // already known to exist
1402                 }
1403
1404                 $table = $this->tableName( $table );
1405                 $old = $this->ignoreErrors( true );
1406                 $res = $this->query( "SELECT 1 FROM $table LIMIT 1", $fname );
1407                 $this->ignoreErrors( $old );
1408
1409                 return (bool)$res;
1410         }
1411
1412         public function indexUnique( $table, $index ) {
1413                 $indexInfo = $this->indexInfo( $table, $index );
1414
1415                 if ( !$indexInfo ) {
1416                         return null;
1417                 }
1418
1419                 return !$indexInfo[0]->Non_unique;
1420         }
1421
1422         /**
1423          * Helper for DatabaseBase::insert().
1424          *
1425          * @param array $options
1426          * @return string
1427          */
1428         protected function makeInsertOptions( $options ) {
1429                 return implode( ' ', $options );
1430         }
1431
1432         public function insert( $table, $a, $fname = __METHOD__, $options = [] ) {
1433                 # No rows to insert, easy just return now
1434                 if ( !count( $a ) ) {
1435                         return true;
1436                 }
1437
1438                 $table = $this->tableName( $table );
1439
1440                 if ( !is_array( $options ) ) {
1441                         $options = [ $options ];
1442                 }
1443
1444                 $fh = null;
1445                 if ( isset( $options['fileHandle'] ) ) {
1446                         $fh = $options['fileHandle'];
1447                 }
1448                 $options = $this->makeInsertOptions( $options );
1449
1450                 if ( isset( $a[0] ) && is_array( $a[0] ) ) {
1451                         $multi = true;
1452                         $keys = array_keys( $a[0] );
1453                 } else {
1454                         $multi = false;
1455                         $keys = array_keys( $a );
1456                 }
1457
1458                 $sql = 'INSERT ' . $options .
1459                         " INTO $table (" . implode( ',', $keys ) . ') VALUES ';
1460
1461                 if ( $multi ) {
1462                         $first = true;
1463                         foreach ( $a as $row ) {
1464                                 if ( $first ) {
1465                                         $first = false;
1466                                 } else {
1467                                         $sql .= ',';
1468                                 }
1469                                 $sql .= '(' . $this->makeList( $row ) . ')';
1470                         }
1471                 } else {
1472                         $sql .= '(' . $this->makeList( $a ) . ')';
1473                 }
1474
1475                 if ( $fh !== null && false === fwrite( $fh, $sql ) ) {
1476                         return false;
1477                 } elseif ( $fh !== null ) {
1478                         return true;
1479                 }
1480
1481                 return (bool)$this->query( $sql, $fname );
1482         }
1483
1484         /**
1485          * Make UPDATE options array for DatabaseBase::makeUpdateOptions
1486          *
1487          * @param array $options
1488          * @return array
1489          */
1490         protected function makeUpdateOptionsArray( $options ) {
1491                 if ( !is_array( $options ) ) {
1492                         $options = [ $options ];
1493                 }
1494
1495                 $opts = [];
1496
1497                 if ( in_array( 'IGNORE', $options ) ) {
1498                         $opts[] = 'IGNORE';
1499                 }
1500
1501                 return $opts;
1502         }
1503
1504         /**
1505          * Make UPDATE options for the DatabaseBase::update function
1506          *
1507          * @param array $options The options passed to DatabaseBase::update
1508          * @return string
1509          */
1510         protected function makeUpdateOptions( $options ) {
1511                 $opts = $this->makeUpdateOptionsArray( $options );
1512
1513                 return implode( ' ', $opts );
1514         }
1515
1516         public function update( $table, $values, $conds, $fname = __METHOD__, $options = [] ) {
1517                 $table = $this->tableName( $table );
1518                 $opts = $this->makeUpdateOptions( $options );
1519                 $sql = "UPDATE $opts $table SET " . $this->makeList( $values, self::LIST_SET );
1520
1521                 if ( $conds !== [] && $conds !== '*' ) {
1522                         $sql .= " WHERE " . $this->makeList( $conds, self::LIST_AND );
1523                 }
1524
1525                 return $this->query( $sql, $fname );
1526         }
1527
1528         public function makeList( $a, $mode = self::LIST_COMMA ) {
1529                 if ( !is_array( $a ) ) {
1530                         throw new DBUnexpectedError( $this, __METHOD__ . ' called with incorrect parameters' );
1531                 }
1532
1533                 $first = true;
1534                 $list = '';
1535
1536                 foreach ( $a as $field => $value ) {
1537                         if ( !$first ) {
1538                                 if ( $mode == self::LIST_AND ) {
1539                                         $list .= ' AND ';
1540                                 } elseif ( $mode == self::LIST_OR ) {
1541                                         $list .= ' OR ';
1542                                 } else {
1543                                         $list .= ',';
1544                                 }
1545                         } else {
1546                                 $first = false;
1547                         }
1548
1549                         if ( ( $mode == self::LIST_AND || $mode == self::LIST_OR ) && is_numeric( $field ) ) {
1550                                 $list .= "($value)";
1551                         } elseif ( $mode == self::LIST_SET && is_numeric( $field ) ) {
1552                                 $list .= "$value";
1553                         } elseif (
1554                                 ( $mode == self::LIST_AND || $mode == self::LIST_OR ) && is_array( $value )
1555                         ) {
1556                                 // Remove null from array to be handled separately if found
1557                                 $includeNull = false;
1558                                 foreach ( array_keys( $value, null, true ) as $nullKey ) {
1559                                         $includeNull = true;
1560                                         unset( $value[$nullKey] );
1561                                 }
1562                                 if ( count( $value ) == 0 && !$includeNull ) {
1563                                         throw new InvalidArgumentException(
1564                                                 __METHOD__ . ": empty input for field $field" );
1565                                 } elseif ( count( $value ) == 0 ) {
1566                                         // only check if $field is null
1567                                         $list .= "$field IS NULL";
1568                                 } else {
1569                                         // IN clause contains at least one valid element
1570                                         if ( $includeNull ) {
1571                                                 // Group subconditions to ensure correct precedence
1572                                                 $list .= '(';
1573                                         }
1574                                         if ( count( $value ) == 1 ) {
1575                                                 // Special-case single values, as IN isn't terribly efficient
1576                                                 // Don't necessarily assume the single key is 0; we don't
1577                                                 // enforce linear numeric ordering on other arrays here.
1578                                                 $value = array_values( $value )[0];
1579                                                 $list .= $field . " = " . $this->addQuotes( $value );
1580                                         } else {
1581                                                 $list .= $field . " IN (" . $this->makeList( $value ) . ") ";
1582                                         }
1583                                         // if null present in array, append IS NULL
1584                                         if ( $includeNull ) {
1585                                                 $list .= " OR $field IS NULL)";
1586                                         }
1587                                 }
1588                         } elseif ( $value === null ) {
1589                                 if ( $mode == self::LIST_AND || $mode == self::LIST_OR ) {
1590                                         $list .= "$field IS ";
1591                                 } elseif ( $mode == self::LIST_SET ) {
1592                                         $list .= "$field = ";
1593                                 }
1594                                 $list .= 'NULL';
1595                         } else {
1596                                 if (
1597                                         $mode == self::LIST_AND || $mode == self::LIST_OR || $mode == self::LIST_SET
1598                                 ) {
1599                                         $list .= "$field = ";
1600                                 }
1601                                 $list .= $mode == self::LIST_NAMES ? $value : $this->addQuotes( $value );
1602                         }
1603                 }
1604
1605                 return $list;
1606         }
1607
1608         public function makeWhereFrom2d( $data, $baseKey, $subKey ) {
1609                 $conds = [];
1610
1611                 foreach ( $data as $base => $sub ) {
1612                         if ( count( $sub ) ) {
1613                                 $conds[] = $this->makeList(
1614                                         [ $baseKey => $base, $subKey => array_keys( $sub ) ],
1615                                         self::LIST_AND );
1616                         }
1617                 }
1618
1619                 if ( $conds ) {
1620                         return $this->makeList( $conds, self::LIST_OR );
1621                 } else {
1622                         // Nothing to search for...
1623                         return false;
1624                 }
1625         }
1626
1627         public function aggregateValue( $valuedata, $valuename = 'value' ) {
1628                 return $valuename;
1629         }
1630
1631         public function bitNot( $field ) {
1632                 return "(~$field)";
1633         }
1634
1635         public function bitAnd( $fieldLeft, $fieldRight ) {
1636                 return "($fieldLeft & $fieldRight)";
1637         }
1638
1639         public function bitOr( $fieldLeft, $fieldRight ) {
1640                 return "($fieldLeft | $fieldRight)";
1641         }
1642
1643         public function buildConcat( $stringList ) {
1644                 return 'CONCAT(' . implode( ',', $stringList ) . ')';
1645         }
1646
1647         public function buildGroupConcatField(
1648                 $delim, $table, $field, $conds = '', $join_conds = []
1649         ) {
1650                 $fld = "GROUP_CONCAT($field SEPARATOR " . $this->addQuotes( $delim ) . ')';
1651
1652                 return '(' . $this->selectSQLText( $table, $fld, $conds, null, [], $join_conds ) . ')';
1653         }
1654
1655         public function buildStringCast( $field ) {
1656                 return $field;
1657         }
1658
1659         public function selectDB( $db ) {
1660                 # Stub. Shouldn't cause serious problems if it's not overridden, but
1661                 # if your database engine supports a concept similar to MySQL's
1662                 # databases you may as well.
1663                 $this->mDBname = $db;
1664
1665                 return true;
1666         }
1667
1668         public function getDBname() {
1669                 return $this->mDBname;
1670         }
1671
1672         public function getServer() {
1673                 return $this->mServer;
1674         }
1675
1676         /**
1677          * Format a table name ready for use in constructing an SQL query
1678          *
1679          * This does two important things: it quotes the table names to clean them up,
1680          * and it adds a table prefix if only given a table name with no quotes.
1681          *
1682          * All functions of this object which require a table name call this function
1683          * themselves. Pass the canonical name to such functions. This is only needed
1684          * when calling query() directly.
1685          *
1686          * @note This function does not sanitize user input. It is not safe to use
1687          *   this function to escape user input.
1688          * @param string $name Database table name
1689          * @param string $format One of:
1690          *   quoted - Automatically pass the table name through addIdentifierQuotes()
1691          *            so that it can be used in a query.
1692          *   raw - Do not add identifier quotes to the table name
1693          * @return string Full database name
1694          */
1695         public function tableName( $name, $format = 'quoted' ) {
1696                 # Skip the entire process when we have a string quoted on both ends.
1697                 # Note that we check the end so that we will still quote any use of
1698                 # use of `database`.table. But won't break things if someone wants
1699                 # to query a database table with a dot in the name.
1700                 if ( $this->isQuotedIdentifier( $name ) ) {
1701                         return $name;
1702                 }
1703
1704                 # Lets test for any bits of text that should never show up in a table
1705                 # name. Basically anything like JOIN or ON which are actually part of
1706                 # SQL queries, but may end up inside of the table value to combine
1707                 # sql. Such as how the API is doing.
1708                 # Note that we use a whitespace test rather than a \b test to avoid
1709                 # any remote case where a word like on may be inside of a table name
1710                 # surrounded by symbols which may be considered word breaks.
1711                 if ( preg_match( '/(^|\s)(DISTINCT|JOIN|ON|AS)(\s|$)/i', $name ) !== 0 ) {
1712                         return $name;
1713                 }
1714
1715                 # Split database and table into proper variables.
1716                 # We reverse the explode so that database.table and table both output
1717                 # the correct table.
1718                 $dbDetails = explode( '.', $name, 3 );
1719                 if ( count( $dbDetails ) == 3 ) {
1720                         list( $database, $schema, $table ) = $dbDetails;
1721                         # We don't want any prefix added in this case
1722                         $prefix = '';
1723                 } elseif ( count( $dbDetails ) == 2 ) {
1724                         list( $database, $table ) = $dbDetails;
1725                         # We don't want any prefix added in this case
1726                         # In dbs that support it, $database may actually be the schema
1727                         # but that doesn't affect any of the functionality here
1728                         $prefix = '';
1729                         $schema = '';
1730                 } else {
1731                         list( $table ) = $dbDetails;
1732                         if ( isset( $this->tableAliases[$table] ) ) {
1733                                 $database = $this->tableAliases[$table]['dbname'];
1734                                 $schema = is_string( $this->tableAliases[$table]['schema'] )
1735                                         ? $this->tableAliases[$table]['schema']
1736                                         : $this->mSchema;
1737                                 $prefix = is_string( $this->tableAliases[$table]['prefix'] )
1738                                         ? $this->tableAliases[$table]['prefix']
1739                                         : $this->mTablePrefix;
1740                         } else {
1741                                 $database = '';
1742                                 $schema = $this->mSchema; # Default schema
1743                                 $prefix = $this->mTablePrefix; # Default prefix
1744                         }
1745                 }
1746
1747                 # Quote $table and apply the prefix if not quoted.
1748                 # $tableName might be empty if this is called from Database::replaceVars()
1749                 $tableName = "{$prefix}{$table}";
1750                 if ( $format == 'quoted'
1751                         && !$this->isQuotedIdentifier( $tableName ) && $tableName !== ''
1752                 ) {
1753                         $tableName = $this->addIdentifierQuotes( $tableName );
1754                 }
1755
1756                 # Quote $schema and merge it with the table name if needed
1757                 if ( strlen( $schema ) ) {
1758                         if ( $format == 'quoted' && !$this->isQuotedIdentifier( $schema ) ) {
1759                                 $schema = $this->addIdentifierQuotes( $schema );
1760                         }
1761                         $tableName = $schema . '.' . $tableName;
1762                 }
1763
1764                 # Quote $database and merge it with the table name if needed
1765                 if ( $database !== '' ) {
1766                         if ( $format == 'quoted' && !$this->isQuotedIdentifier( $database ) ) {
1767                                 $database = $this->addIdentifierQuotes( $database );
1768                         }
1769                         $tableName = $database . '.' . $tableName;
1770                 }
1771
1772                 return $tableName;
1773         }
1774
1775         /**
1776          * Fetch a number of table names into an array
1777          * This is handy when you need to construct SQL for joins
1778          *
1779          * Example:
1780          * extract( $dbr->tableNames( 'user', 'watchlist' ) );
1781          * $sql = "SELECT wl_namespace,wl_title FROM $watchlist,$user
1782          *         WHERE wl_user=user_id AND wl_user=$nameWithQuotes";
1783          *
1784          * @return array
1785          */
1786         public function tableNames() {
1787                 $inArray = func_get_args();
1788                 $retVal = [];
1789
1790                 foreach ( $inArray as $name ) {
1791                         $retVal[$name] = $this->tableName( $name );
1792                 }
1793
1794                 return $retVal;
1795         }
1796
1797         /**
1798          * Fetch a number of table names into an zero-indexed numerical array
1799          * This is handy when you need to construct SQL for joins
1800          *
1801          * Example:
1802          * list( $user, $watchlist ) = $dbr->tableNamesN( 'user', 'watchlist' );
1803          * $sql = "SELECT wl_namespace,wl_title FROM $watchlist,$user
1804          *         WHERE wl_user=user_id AND wl_user=$nameWithQuotes";
1805          *
1806          * @return array
1807          */
1808         public function tableNamesN() {
1809                 $inArray = func_get_args();
1810                 $retVal = [];
1811
1812                 foreach ( $inArray as $name ) {
1813                         $retVal[] = $this->tableName( $name );
1814                 }
1815
1816                 return $retVal;
1817         }
1818
1819         /**
1820          * Get an aliased table name
1821          * e.g. tableName AS newTableName
1822          *
1823          * @param string $name Table name, see tableName()
1824          * @param string|bool $alias Alias (optional)
1825          * @return string SQL name for aliased table. Will not alias a table to its own name
1826          */
1827         protected function tableNameWithAlias( $name, $alias = false ) {
1828                 if ( !$alias || $alias == $name ) {
1829                         return $this->tableName( $name );
1830                 } else {
1831                         return $this->tableName( $name ) . ' ' . $this->addIdentifierQuotes( $alias );
1832                 }
1833         }
1834
1835         /**
1836          * Gets an array of aliased table names
1837          *
1838          * @param array $tables [ [alias] => table ]
1839          * @return string[] See tableNameWithAlias()
1840          */
1841         protected function tableNamesWithAlias( $tables ) {
1842                 $retval = [];
1843                 foreach ( $tables as $alias => $table ) {
1844                         if ( is_numeric( $alias ) ) {
1845                                 $alias = $table;
1846                         }
1847                         $retval[] = $this->tableNameWithAlias( $table, $alias );
1848                 }
1849
1850                 return $retval;
1851         }
1852
1853         /**
1854          * Get an aliased field name
1855          * e.g. fieldName AS newFieldName
1856          *
1857          * @param string $name Field name
1858          * @param string|bool $alias Alias (optional)
1859          * @return string SQL name for aliased field. Will not alias a field to its own name
1860          */
1861         protected function fieldNameWithAlias( $name, $alias = false ) {
1862                 if ( !$alias || (string)$alias === (string)$name ) {
1863                         return $name;
1864                 } else {
1865                         return $name . ' AS ' . $this->addIdentifierQuotes( $alias ); // PostgreSQL needs AS
1866                 }
1867         }
1868
1869         /**
1870          * Gets an array of aliased field names
1871          *
1872          * @param array $fields [ [alias] => field ]
1873          * @return string[] See fieldNameWithAlias()
1874          */
1875         protected function fieldNamesWithAlias( $fields ) {
1876                 $retval = [];
1877                 foreach ( $fields as $alias => $field ) {
1878                         if ( is_numeric( $alias ) ) {
1879                                 $alias = $field;
1880                         }
1881                         $retval[] = $this->fieldNameWithAlias( $field, $alias );
1882                 }
1883
1884                 return $retval;
1885         }
1886
1887         /**
1888          * Get the aliased table name clause for a FROM clause
1889          * which might have a JOIN and/or USE INDEX or IGNORE INDEX clause
1890          *
1891          * @param array $tables ( [alias] => table )
1892          * @param array $use_index Same as for select()
1893          * @param array $ignore_index Same as for select()
1894          * @param array $join_conds Same as for select()
1895          * @return string
1896          */
1897         protected function tableNamesWithIndexClauseOrJOIN(
1898                 $tables, $use_index = [], $ignore_index = [], $join_conds = []
1899         ) {
1900                 $ret = [];
1901                 $retJOIN = [];
1902                 $use_index = (array)$use_index;
1903                 $ignore_index = (array)$ignore_index;
1904                 $join_conds = (array)$join_conds;
1905
1906                 foreach ( $tables as $alias => $table ) {
1907                         if ( !is_string( $alias ) ) {
1908                                 // No alias? Set it equal to the table name
1909                                 $alias = $table;
1910                         }
1911                         // Is there a JOIN clause for this table?
1912                         if ( isset( $join_conds[$alias] ) ) {
1913                                 list( $joinType, $conds ) = $join_conds[$alias];
1914                                 $tableClause = $joinType;
1915                                 $tableClause .= ' ' . $this->tableNameWithAlias( $table, $alias );
1916                                 if ( isset( $use_index[$alias] ) ) { // has USE INDEX?
1917                                         $use = $this->useIndexClause( implode( ',', (array)$use_index[$alias] ) );
1918                                         if ( $use != '' ) {
1919                                                 $tableClause .= ' ' . $use;
1920                                         }
1921                                 }
1922                                 if ( isset( $ignore_index[$alias] ) ) { // has IGNORE INDEX?
1923                                         $ignore = $this->ignoreIndexClause(
1924                                                 implode( ',', (array)$ignore_index[$alias] ) );
1925                                         if ( $ignore != '' ) {
1926                                                 $tableClause .= ' ' . $ignore;
1927                                         }
1928                                 }
1929                                 $on = $this->makeList( (array)$conds, self::LIST_AND );
1930                                 if ( $on != '' ) {
1931                                         $tableClause .= ' ON (' . $on . ')';
1932                                 }
1933
1934                                 $retJOIN[] = $tableClause;
1935                         } elseif ( isset( $use_index[$alias] ) ) {
1936                                 // Is there an INDEX clause for this table?
1937                                 $tableClause = $this->tableNameWithAlias( $table, $alias );
1938                                 $tableClause .= ' ' . $this->useIndexClause(
1939                                                 implode( ',', (array)$use_index[$alias] )
1940                                         );
1941
1942                                 $ret[] = $tableClause;
1943                         } elseif ( isset( $ignore_index[$alias] ) ) {
1944                                 // Is there an INDEX clause for this table?
1945                                 $tableClause = $this->tableNameWithAlias( $table, $alias );
1946                                 $tableClause .= ' ' . $this->ignoreIndexClause(
1947                                                 implode( ',', (array)$ignore_index[$alias] )
1948                                         );
1949
1950                                 $ret[] = $tableClause;
1951                         } else {
1952                                 $tableClause = $this->tableNameWithAlias( $table, $alias );
1953
1954                                 $ret[] = $tableClause;
1955                         }
1956                 }
1957
1958                 // We can't separate explicit JOIN clauses with ',', use ' ' for those
1959                 $implicitJoins = !empty( $ret ) ? implode( ',', $ret ) : "";
1960                 $explicitJoins = !empty( $retJOIN ) ? implode( ' ', $retJOIN ) : "";
1961
1962                 // Compile our final table clause
1963                 return implode( ' ', [ $implicitJoins, $explicitJoins ] );
1964         }
1965
1966         /**
1967          * Get the name of an index in a given table.
1968          *
1969          * @param string $index
1970          * @return string
1971          */
1972         protected function indexName( $index ) {
1973                 return $index;
1974         }
1975
1976         public function addQuotes( $s ) {
1977                 if ( $s instanceof Blob ) {
1978                         $s = $s->fetch();
1979                 }
1980                 if ( $s === null ) {
1981                         return 'NULL';
1982                 } elseif ( is_bool( $s ) ) {
1983                         return (int)$s;
1984                 } else {
1985                         # This will also quote numeric values. This should be harmless,
1986                         # and protects against weird problems that occur when they really
1987                         # _are_ strings such as article titles and string->number->string
1988                         # conversion is not 1:1.
1989                         return "'" . $this->strencode( $s ) . "'";
1990                 }
1991         }
1992
1993         /**
1994          * Quotes an identifier using `backticks` or "double quotes" depending on the database type.
1995          * MySQL uses `backticks` while basically everything else uses double quotes.
1996          * Since MySQL is the odd one out here the double quotes are our generic
1997          * and we implement backticks in DatabaseMysql.
1998          *
1999          * @param string $s
2000          * @return string
2001          */
2002         public function addIdentifierQuotes( $s ) {
2003                 return '"' . str_replace( '"', '""', $s ) . '"';
2004         }
2005
2006         /**
2007          * Returns if the given identifier looks quoted or not according to
2008          * the database convention for quoting identifiers .
2009          *
2010          * @note Do not use this to determine if untrusted input is safe.
2011          *   A malicious user can trick this function.
2012          * @param string $name
2013          * @return bool
2014          */
2015         public function isQuotedIdentifier( $name ) {
2016                 return $name[0] == '"' && substr( $name, -1, 1 ) == '"';
2017         }
2018
2019         /**
2020          * @param string $s
2021          * @return string
2022          */
2023         protected function escapeLikeInternal( $s ) {
2024                 return addcslashes( $s, '\%_' );
2025         }
2026
2027         public function buildLike() {
2028                 $params = func_get_args();
2029
2030                 if ( count( $params ) > 0 && is_array( $params[0] ) ) {
2031                         $params = $params[0];
2032                 }
2033
2034                 $s = '';
2035
2036                 foreach ( $params as $value ) {
2037                         if ( $value instanceof LikeMatch ) {
2038                                 $s .= $value->toString();
2039                         } else {
2040                                 $s .= $this->escapeLikeInternal( $value );
2041                         }
2042                 }
2043
2044                 return " LIKE {$this->addQuotes( $s )} ";
2045         }
2046
2047         public function anyChar() {
2048                 return new LikeMatch( '_' );
2049         }
2050
2051         public function anyString() {
2052                 return new LikeMatch( '%' );
2053         }
2054
2055         public function nextSequenceValue( $seqName ) {
2056                 return null;
2057         }
2058
2059         /**
2060          * USE INDEX clause. Unlikely to be useful for anything but MySQL. This
2061          * is only needed because a) MySQL must be as efficient as possible due to
2062          * its use on Wikipedia, and b) MySQL 4.0 is kind of dumb sometimes about
2063          * which index to pick. Anyway, other databases might have different
2064          * indexes on a given table. So don't bother overriding this unless you're
2065          * MySQL.
2066          * @param string $index
2067          * @return string
2068          */
2069         public function useIndexClause( $index ) {
2070                 return '';
2071         }
2072
2073         /**
2074          * IGNORE INDEX clause. Unlikely to be useful for anything but MySQL. This
2075          * is only needed because a) MySQL must be as efficient as possible due to
2076          * its use on Wikipedia, and b) MySQL 4.0 is kind of dumb sometimes about
2077          * which index to pick. Anyway, other databases might have different
2078          * indexes on a given table. So don't bother overriding this unless you're
2079          * MySQL.
2080          * @param string $index
2081          * @return string
2082          */
2083         public function ignoreIndexClause( $index ) {
2084                 return '';
2085         }
2086
2087         public function replace( $table, $uniqueIndexes, $rows, $fname = __METHOD__ ) {
2088                 $quotedTable = $this->tableName( $table );
2089
2090                 if ( count( $rows ) == 0 ) {
2091                         return;
2092                 }
2093
2094                 # Single row case
2095                 if ( !is_array( reset( $rows ) ) ) {
2096                         $rows = [ $rows ];
2097                 }
2098
2099                 // @FXIME: this is not atomic, but a trx would break affectedRows()
2100                 foreach ( $rows as $row ) {
2101                         # Delete rows which collide
2102                         if ( $uniqueIndexes ) {
2103                                 $sql = "DELETE FROM $quotedTable WHERE ";
2104                                 $first = true;
2105                                 foreach ( $uniqueIndexes as $index ) {
2106                                         if ( $first ) {
2107                                                 $first = false;
2108                                                 $sql .= '( ';
2109                                         } else {
2110                                                 $sql .= ' ) OR ( ';
2111                                         }
2112                                         if ( is_array( $index ) ) {
2113                                                 $first2 = true;
2114                                                 foreach ( $index as $col ) {
2115                                                         if ( $first2 ) {
2116                                                                 $first2 = false;
2117                                                         } else {
2118                                                                 $sql .= ' AND ';
2119                                                         }
2120                                                         $sql .= $col . '=' . $this->addQuotes( $row[$col] );
2121                                                 }
2122                                         } else {
2123                                                 $sql .= $index . '=' . $this->addQuotes( $row[$index] );
2124                                         }
2125                                 }
2126                                 $sql .= ' )';
2127                                 $this->query( $sql, $fname );
2128                         }
2129
2130                         # Now insert the row
2131                         $this->insert( $table, $row, $fname );
2132                 }
2133         }
2134
2135         /**
2136          * REPLACE query wrapper for MySQL and SQLite, which have a native REPLACE
2137          * statement.
2138          *
2139          * @param string $table Table name
2140          * @param array|string $rows Row(s) to insert
2141          * @param string $fname Caller function name
2142          *
2143          * @return ResultWrapper
2144          */
2145         protected function nativeReplace( $table, $rows, $fname ) {
2146                 $table = $this->tableName( $table );
2147
2148                 # Single row case
2149                 if ( !is_array( reset( $rows ) ) ) {
2150                         $rows = [ $rows ];
2151                 }
2152
2153                 $sql = "REPLACE INTO $table (" . implode( ',', array_keys( $rows[0] ) ) . ') VALUES ';
2154                 $first = true;
2155
2156                 foreach ( $rows as $row ) {
2157                         if ( $first ) {
2158                                 $first = false;
2159                         } else {
2160                                 $sql .= ',';
2161                         }
2162
2163                         $sql .= '(' . $this->makeList( $row ) . ')';
2164                 }
2165
2166                 return $this->query( $sql, $fname );
2167         }
2168
2169         public function upsert( $table, array $rows, array $uniqueIndexes, array $set,
2170                 $fname = __METHOD__
2171         ) {
2172                 if ( !count( $rows ) ) {
2173                         return true; // nothing to do
2174                 }
2175
2176                 if ( !is_array( reset( $rows ) ) ) {
2177                         $rows = [ $rows ];
2178                 }
2179
2180                 if ( count( $uniqueIndexes ) ) {
2181                         $clauses = []; // list WHERE clauses that each identify a single row
2182                         foreach ( $rows as $row ) {
2183                                 foreach ( $uniqueIndexes as $index ) {
2184                                         $index = is_array( $index ) ? $index : [ $index ]; // columns
2185                                         $rowKey = []; // unique key to this row
2186                                         foreach ( $index as $column ) {
2187                                                 $rowKey[$column] = $row[$column];
2188                                         }
2189                                         $clauses[] = $this->makeList( $rowKey, self::LIST_AND );
2190                                 }
2191                         }
2192                         $where = [ $this->makeList( $clauses, self::LIST_OR ) ];
2193                 } else {
2194                         $where = false;
2195                 }
2196
2197                 $useTrx = !$this->mTrxLevel;
2198                 if ( $useTrx ) {
2199                         $this->begin( $fname, self::TRANSACTION_INTERNAL );
2200                 }
2201                 try {
2202                         # Update any existing conflicting row(s)
2203                         if ( $where !== false ) {
2204                                 $ok = $this->update( $table, $set, $where, $fname );
2205                         } else {
2206                                 $ok = true;
2207                         }
2208                         # Now insert any non-conflicting row(s)
2209                         $ok = $this->insert( $table, $rows, $fname, [ 'IGNORE' ] ) && $ok;
2210                 } catch ( Exception $e ) {
2211                         if ( $useTrx ) {
2212                                 $this->rollback( $fname, self::FLUSHING_INTERNAL );
2213                         }
2214                         throw $e;
2215                 }
2216                 if ( $useTrx ) {
2217                         $this->commit( $fname, self::FLUSHING_INTERNAL );
2218                 }
2219
2220                 return $ok;
2221         }
2222
2223         public function deleteJoin( $delTable, $joinTable, $delVar, $joinVar, $conds,
2224                 $fname = __METHOD__
2225         ) {
2226                 if ( !$conds ) {
2227                         throw new DBUnexpectedError( $this, __METHOD__ . ' called with empty $conds' );
2228                 }
2229
2230                 $delTable = $this->tableName( $delTable );
2231                 $joinTable = $this->tableName( $joinTable );
2232                 $sql = "DELETE FROM $delTable WHERE $delVar IN (SELECT $joinVar FROM $joinTable ";
2233                 if ( $conds != '*' ) {
2234                         $sql .= 'WHERE ' . $this->makeList( $conds, self::LIST_AND );
2235                 }
2236                 $sql .= ')';
2237
2238                 $this->query( $sql, $fname );
2239         }
2240
2241         /**
2242          * Returns the size of a text field, or -1 for "unlimited"
2243          *
2244          * @param string $table
2245          * @param string $field
2246          * @return int
2247          */
2248         public function textFieldSize( $table, $field ) {
2249                 $table = $this->tableName( $table );
2250                 $sql = "SHOW COLUMNS FROM $table LIKE \"$field\";";
2251                 $res = $this->query( $sql, __METHOD__ );
2252                 $row = $this->fetchObject( $res );
2253
2254                 $m = [];
2255
2256                 if ( preg_match( '/\((.*)\)/', $row->Type, $m ) ) {
2257                         $size = $m[1];
2258                 } else {
2259                         $size = -1;
2260                 }
2261
2262                 return $size;
2263         }
2264
2265         public function delete( $table, $conds, $fname = __METHOD__ ) {
2266                 if ( !$conds ) {
2267                         throw new DBUnexpectedError( $this, __METHOD__ . ' called with no conditions' );
2268                 }
2269
2270                 $table = $this->tableName( $table );
2271                 $sql = "DELETE FROM $table";
2272
2273                 if ( $conds != '*' ) {
2274                         if ( is_array( $conds ) ) {
2275                                 $conds = $this->makeList( $conds, self::LIST_AND );
2276                         }
2277                         $sql .= ' WHERE ' . $conds;
2278                 }
2279
2280                 return $this->query( $sql, $fname );
2281         }
2282
2283         public function insertSelect(
2284                 $destTable, $srcTable, $varMap, $conds,
2285                 $fname = __METHOD__, $insertOptions = [], $selectOptions = []
2286         ) {
2287                 if ( $this->cliMode ) {
2288                         // For massive migrations with downtime, we don't want to select everything
2289                         // into memory and OOM, so do all this native on the server side if possible.
2290                         return $this->nativeInsertSelect(
2291                                 $destTable,
2292                                 $srcTable,
2293                                 $varMap,
2294                                 $conds,
2295                                 $fname,
2296                                 $insertOptions,
2297                                 $selectOptions
2298                         );
2299                 }
2300
2301                 // For web requests, do a locking SELECT and then INSERT. This puts the SELECT burden
2302                 // on only the master (without needing row-based-replication). It also makes it easy to
2303                 // know how big the INSERT is going to be.
2304                 $fields = [];
2305                 foreach ( $varMap as $dstColumn => $sourceColumnOrSql ) {
2306                         $fields[] = $this->fieldNameWithAlias( $sourceColumnOrSql, $dstColumn );
2307                 }
2308                 $selectOptions[] = 'FOR UPDATE';
2309                 $res = $this->select( $srcTable, implode( ',', $fields ), $conds, $fname, $selectOptions );
2310                 if ( !$res ) {
2311                         return false;
2312                 }
2313
2314                 $rows = [];
2315                 foreach ( $res as $row ) {
2316                         $rows[] = (array)$row;
2317                 }
2318
2319                 return $this->insert( $destTable, $rows, $fname, $insertOptions );
2320         }
2321
2322         protected function nativeInsertSelect( $destTable, $srcTable, $varMap, $conds,
2323                 $fname = __METHOD__,
2324                 $insertOptions = [], $selectOptions = []
2325         ) {
2326                 $destTable = $this->tableName( $destTable );
2327
2328                 if ( !is_array( $insertOptions ) ) {
2329                         $insertOptions = [ $insertOptions ];
2330                 }
2331
2332                 $insertOptions = $this->makeInsertOptions( $insertOptions );
2333
2334                 if ( !is_array( $selectOptions ) ) {
2335                         $selectOptions = [ $selectOptions ];
2336                 }
2337
2338                 list( $startOpts, $useIndex, $tailOpts, $ignoreIndex ) = $this->makeSelectOptions(
2339                         $selectOptions );
2340
2341                 if ( is_array( $srcTable ) ) {
2342                         $srcTable = implode( ',', array_map( [ &$this, 'tableName' ], $srcTable ) );
2343                 } else {
2344                         $srcTable = $this->tableName( $srcTable );
2345                 }
2346
2347                 $sql = "INSERT $insertOptions" .
2348                         " INTO $destTable (" . implode( ',', array_keys( $varMap ) ) . ')' .
2349                         " SELECT $startOpts " . implode( ',', $varMap ) .
2350                         " FROM $srcTable $useIndex $ignoreIndex ";
2351
2352                 if ( $conds != '*' ) {
2353                         if ( is_array( $conds ) ) {
2354                                 $conds = $this->makeList( $conds, self::LIST_AND );
2355                         }
2356                         $sql .= " WHERE $conds";
2357                 }
2358
2359                 $sql .= " $tailOpts";
2360
2361                 return $this->query( $sql, $fname );
2362         }
2363
2364         /**
2365          * Construct a LIMIT query with optional offset. This is used for query
2366          * pages. The SQL should be adjusted so that only the first $limit rows
2367          * are returned. If $offset is provided as well, then the first $offset
2368          * rows should be discarded, and the next $limit rows should be returned.
2369          * If the result of the query is not ordered, then the rows to be returned
2370          * are theoretically arbitrary.
2371          *
2372          * $sql is expected to be a SELECT, if that makes a difference.
2373          *
2374          * The version provided by default works in MySQL and SQLite. It will very
2375          * likely need to be overridden for most other DBMSes.
2376          *
2377          * @param string $sql SQL query we will append the limit too
2378          * @param int $limit The SQL limit
2379          * @param int|bool $offset The SQL offset (default false)
2380          * @throws DBUnexpectedError
2381          * @return string
2382          */
2383         public function limitResult( $sql, $limit, $offset = false ) {
2384                 if ( !is_numeric( $limit ) ) {
2385                         throw new DBUnexpectedError( $this,
2386                                 "Invalid non-numeric limit passed to limitResult()\n" );
2387                 }
2388
2389                 return "$sql LIMIT "
2390                 . ( ( is_numeric( $offset ) && $offset != 0 ) ? "{$offset}," : "" )
2391                 . "{$limit} ";
2392         }
2393
2394         public function unionSupportsOrderAndLimit() {
2395                 return true; // True for almost every DB supported
2396         }
2397
2398         public function unionQueries( $sqls, $all ) {
2399                 $glue = $all ? ') UNION ALL (' : ') UNION (';
2400
2401                 return '(' . implode( $glue, $sqls ) . ')';
2402         }
2403
2404         public function conditional( $cond, $trueVal, $falseVal ) {
2405                 if ( is_array( $cond ) ) {
2406                         $cond = $this->makeList( $cond, self::LIST_AND );
2407                 }
2408
2409                 return " (CASE WHEN $cond THEN $trueVal ELSE $falseVal END) ";
2410         }
2411
2412         public function strreplace( $orig, $old, $new ) {
2413                 return "REPLACE({$orig}, {$old}, {$new})";
2414         }
2415
2416         public function getServerUptime() {
2417                 return 0;
2418         }
2419
2420         public function wasDeadlock() {
2421                 return false;
2422         }
2423
2424         public function wasLockTimeout() {
2425                 return false;
2426         }
2427
2428         public function wasErrorReissuable() {
2429                 return false;
2430         }
2431
2432         public function wasReadOnlyError() {
2433                 return false;
2434         }
2435
2436         /**
2437          * Do not use this method outside of Database/DBError classes
2438          *
2439          * @param integer|string $errno
2440          * @return bool Whether the given query error was a connection drop
2441          */
2442         public function wasConnectionError( $errno ) {
2443                 return false;
2444         }
2445
2446         /**
2447          * Perform a deadlock-prone transaction.
2448          *
2449          * This function invokes a callback function to perform a set of write
2450          * queries. If a deadlock occurs during the processing, the transaction
2451          * will be rolled back and the callback function will be called again.
2452          *
2453          * Avoid using this method outside of Job or Maintenance classes.
2454          *
2455          * Usage:
2456          *   $dbw->deadlockLoop( callback, ... );
2457          *
2458          * Extra arguments are passed through to the specified callback function.
2459          * This method requires that no transactions are already active to avoid
2460          * causing premature commits or exceptions.
2461          *
2462          * Returns whatever the callback function returned on its successful,
2463          * iteration, or false on error, for example if the retry limit was
2464          * reached.
2465          *
2466          * @return mixed
2467          * @throws DBUnexpectedError
2468          * @throws Exception
2469          */
2470         public function deadlockLoop() {
2471                 $args = func_get_args();
2472                 $function = array_shift( $args );
2473                 $tries = self::DEADLOCK_TRIES;
2474
2475                 $this->begin( __METHOD__ );
2476
2477                 $retVal = null;
2478                 /** @var Exception $e */
2479                 $e = null;
2480                 do {
2481                         try {
2482                                 $retVal = call_user_func_array( $function, $args );
2483                                 break;
2484                         } catch ( DBQueryError $e ) {
2485                                 if ( $this->wasDeadlock() ) {
2486                                         // Retry after a randomized delay
2487                                         usleep( mt_rand( self::DEADLOCK_DELAY_MIN, self::DEADLOCK_DELAY_MAX ) );
2488                                 } else {
2489                                         // Throw the error back up
2490                                         throw $e;
2491                                 }
2492                         }
2493                 } while ( --$tries > 0 );
2494
2495                 if ( $tries <= 0 ) {
2496                         // Too many deadlocks; give up
2497                         $this->rollback( __METHOD__ );
2498                         throw $e;
2499                 } else {
2500                         $this->commit( __METHOD__ );
2501
2502                         return $retVal;
2503                 }
2504         }
2505
2506         public function masterPosWait( DBMasterPos $pos, $timeout ) {
2507                 # Real waits are implemented in the subclass.
2508                 return 0;
2509         }
2510
2511         public function getSlavePos() {
2512                 # Stub
2513                 return false;
2514         }
2515
2516         public function getMasterPos() {
2517                 # Stub
2518                 return false;
2519         }
2520
2521         public function serverIsReadOnly() {
2522                 return false;
2523         }
2524
2525         final public function onTransactionResolution( callable $callback, $fname = __METHOD__ ) {
2526                 if ( !$this->mTrxLevel ) {
2527                         throw new DBUnexpectedError( $this, "No transaction is active." );
2528                 }
2529                 $this->mTrxEndCallbacks[] = [ $callback, $fname ];
2530         }
2531
2532         final public function onTransactionIdle( callable $callback, $fname = __METHOD__ ) {
2533                 $this->mTrxIdleCallbacks[] = [ $callback, $fname ];
2534                 if ( !$this->mTrxLevel ) {
2535                         $this->runOnTransactionIdleCallbacks( self::TRIGGER_IDLE );
2536                 }
2537         }
2538
2539         final public function onTransactionPreCommitOrIdle( callable $callback, $fname = __METHOD__ ) {
2540                 if ( $this->mTrxLevel ) {
2541                         $this->mTrxPreCommitCallbacks[] = [ $callback, $fname ];
2542                 } else {
2543                         // If no transaction is active, then make one for this callback
2544                         $this->startAtomic( __METHOD__ );
2545                         try {
2546                                 call_user_func( $callback );
2547                                 $this->endAtomic( __METHOD__ );
2548                         } catch ( Exception $e ) {
2549                                 $this->rollback( __METHOD__, self::FLUSHING_INTERNAL );
2550                                 throw $e;
2551                         }
2552                 }
2553         }
2554
2555         final public function setTransactionListener( $name, callable $callback = null ) {
2556                 if ( $callback ) {
2557                         $this->mTrxRecurringCallbacks[$name] = $callback;
2558                 } else {
2559                         unset( $this->mTrxRecurringCallbacks[$name] );
2560                 }
2561         }
2562
2563         /**
2564          * Whether to disable running of post-COMMIT/ROLLBACK callbacks
2565          *
2566          * This method should not be used outside of Database/LoadBalancer
2567          *
2568          * @param bool $suppress
2569          * @since 1.28
2570          */
2571         final public function setTrxEndCallbackSuppression( $suppress ) {
2572                 $this->mTrxEndCallbacksSuppressed = $suppress;
2573         }
2574
2575         /**
2576          * Actually run and consume any "on transaction idle/resolution" callbacks.
2577          *
2578          * This method should not be used outside of Database/LoadBalancer
2579          *
2580          * @param integer $trigger IDatabase::TRIGGER_* constant
2581          * @since 1.20
2582          * @throws Exception
2583          */
2584         public function runOnTransactionIdleCallbacks( $trigger ) {
2585                 if ( $this->mTrxEndCallbacksSuppressed ) {
2586                         return;
2587                 }
2588
2589                 $autoTrx = $this->getFlag( DBO_TRX ); // automatic begin() enabled?
2590                 /** @var Exception $e */
2591                 $e = null; // first exception
2592                 do { // callbacks may add callbacks :)
2593                         $callbacks = array_merge(
2594                                 $this->mTrxIdleCallbacks,
2595                                 $this->mTrxEndCallbacks // include "transaction resolution" callbacks
2596                         );
2597                         $this->mTrxIdleCallbacks = []; // consumed (and recursion guard)
2598                         $this->mTrxEndCallbacks = []; // consumed (recursion guard)
2599                         foreach ( $callbacks as $callback ) {
2600                                 try {
2601                                         list( $phpCallback ) = $callback;
2602                                         $this->clearFlag( DBO_TRX ); // make each query its own transaction
2603                                         call_user_func_array( $phpCallback, [ $trigger ] );
2604                                         if ( $autoTrx ) {
2605                                                 $this->setFlag( DBO_TRX ); // restore automatic begin()
2606                                         } else {
2607                                                 $this->clearFlag( DBO_TRX ); // restore auto-commit
2608                                         }
2609                                 } catch ( Exception $ex ) {
2610                                         call_user_func( $this->errorLogger, $ex );
2611                                         $e = $e ?: $ex;
2612                                         // Some callbacks may use startAtomic/endAtomic, so make sure
2613                                         // their transactions are ended so other callbacks don't fail
2614                                         if ( $this->trxLevel() ) {
2615                                                 $this->rollback( __METHOD__, self::FLUSHING_INTERNAL );
2616                                         }
2617                                 }
2618                         }
2619                 } while ( count( $this->mTrxIdleCallbacks ) );
2620
2621                 if ( $e instanceof Exception ) {
2622                         throw $e; // re-throw any first exception
2623                 }
2624         }
2625
2626         /**
2627          * Actually run and consume any "on transaction pre-commit" callbacks.
2628          *
2629          * This method should not be used outside of Database/LoadBalancer
2630          *
2631          * @since 1.22
2632          * @throws Exception
2633          */
2634         public function runOnTransactionPreCommitCallbacks() {
2635                 $e = null; // first exception
2636                 do { // callbacks may add callbacks :)
2637                         $callbacks = $this->mTrxPreCommitCallbacks;
2638                         $this->mTrxPreCommitCallbacks = []; // consumed (and recursion guard)
2639                         foreach ( $callbacks as $callback ) {
2640                                 try {
2641                                         list( $phpCallback ) = $callback;
2642                                         call_user_func( $phpCallback );
2643                                 } catch ( Exception $ex ) {
2644                                         call_user_func( $this->errorLogger, $ex );
2645                                         $e = $e ?: $ex;
2646                                 }
2647                         }
2648                 } while ( count( $this->mTrxPreCommitCallbacks ) );
2649
2650                 if ( $e instanceof Exception ) {
2651                         throw $e; // re-throw any first exception
2652                 }
2653         }
2654
2655         /**
2656          * Actually run any "transaction listener" callbacks.
2657          *
2658          * This method should not be used outside of Database/LoadBalancer
2659          *
2660          * @param integer $trigger IDatabase::TRIGGER_* constant
2661          * @throws Exception
2662          * @since 1.20
2663          */
2664         public function runTransactionListenerCallbacks( $trigger ) {
2665                 if ( $this->mTrxEndCallbacksSuppressed ) {
2666                         return;
2667                 }
2668
2669                 /** @var Exception $e */
2670                 $e = null; // first exception
2671
2672                 foreach ( $this->mTrxRecurringCallbacks as $phpCallback ) {
2673                         try {
2674                                 $phpCallback( $trigger, $this );
2675                         } catch ( Exception $ex ) {
2676                                 call_user_func( $this->errorLogger, $ex );
2677                                 $e = $e ?: $ex;
2678                         }
2679                 }
2680
2681                 if ( $e instanceof Exception ) {
2682                         throw $e; // re-throw any first exception
2683                 }
2684         }
2685
2686         final public function startAtomic( $fname = __METHOD__ ) {
2687                 if ( !$this->mTrxLevel ) {
2688                         $this->begin( $fname, self::TRANSACTION_INTERNAL );
2689                         // If DBO_TRX is set, a series of startAtomic/endAtomic pairs will result
2690                         // in all changes being in one transaction to keep requests transactional.
2691                         if ( !$this->getFlag( DBO_TRX ) ) {
2692                                 $this->mTrxAutomaticAtomic = true;
2693                         }
2694                 }
2695
2696                 $this->mTrxAtomicLevels[] = $fname;
2697         }
2698
2699         final public function endAtomic( $fname = __METHOD__ ) {
2700                 if ( !$this->mTrxLevel ) {
2701                         throw new DBUnexpectedError( $this, "No atomic transaction is open (got $fname)." );
2702                 }
2703                 if ( !$this->mTrxAtomicLevels ||
2704                         array_pop( $this->mTrxAtomicLevels ) !== $fname
2705                 ) {
2706                         throw new DBUnexpectedError( $this, "Invalid atomic section ended (got $fname)." );
2707                 }
2708
2709                 if ( !$this->mTrxAtomicLevels && $this->mTrxAutomaticAtomic ) {
2710                         $this->commit( $fname, self::FLUSHING_INTERNAL );
2711                 }
2712         }
2713
2714         final public function doAtomicSection( $fname, callable $callback ) {
2715                 $this->startAtomic( $fname );
2716                 try {
2717                         $res = call_user_func_array( $callback, [ $this, $fname ] );
2718                 } catch ( Exception $e ) {
2719                         $this->rollback( $fname, self::FLUSHING_INTERNAL );
2720                         throw $e;
2721                 }
2722                 $this->endAtomic( $fname );
2723
2724                 return $res;
2725         }
2726
2727         final public function begin( $fname = __METHOD__, $mode = self::TRANSACTION_EXPLICIT ) {
2728                 // Protect against mismatched atomic section, transaction nesting, and snapshot loss
2729                 if ( $this->mTrxLevel ) {
2730                         if ( $this->mTrxAtomicLevels ) {
2731                                 $levels = implode( ', ', $this->mTrxAtomicLevels );
2732                                 $msg = "$fname: Got explicit BEGIN while atomic section(s) $levels are open.";
2733                                 throw new DBUnexpectedError( $this, $msg );
2734                         } elseif ( !$this->mTrxAutomatic ) {
2735                                 $msg = "$fname: Explicit transaction already active (from {$this->mTrxFname}).";
2736                                 throw new DBUnexpectedError( $this, $msg );
2737                         } else {
2738                                 // @TODO: make this an exception at some point
2739                                 $msg = "$fname: Implicit transaction already active (from {$this->mTrxFname}).";
2740                                 $this->queryLogger->error( $msg );
2741                                 return; // join the main transaction set
2742                         }
2743                 } elseif ( $this->getFlag( DBO_TRX ) && $mode !== self::TRANSACTION_INTERNAL ) {
2744                         // @TODO: make this an exception at some point
2745                         $msg = "$fname: Implicit transaction expected (DBO_TRX set).";
2746                         $this->queryLogger->error( $msg );
2747                         return; // let any writes be in the main transaction
2748                 }
2749
2750                 // Avoid fatals if close() was called
2751                 $this->assertOpen();
2752
2753                 $this->doBegin( $fname );
2754                 $this->mTrxTimestamp = microtime( true );
2755                 $this->mTrxFname = $fname;
2756                 $this->mTrxDoneWrites = false;
2757                 $this->mTrxAutomatic = ( $mode === self::TRANSACTION_INTERNAL );
2758                 $this->mTrxAutomaticAtomic = false;
2759                 $this->mTrxAtomicLevels = [];
2760                 $this->mTrxShortId = sprintf( '%06x', mt_rand( 0, 0xffffff ) );
2761                 $this->mTrxWriteDuration = 0.0;
2762                 $this->mTrxWriteQueryCount = 0;
2763                 $this->mTrxWriteAdjDuration = 0.0;
2764                 $this->mTrxWriteAdjQueryCount = 0;
2765                 $this->mTrxWriteCallers = [];
2766                 // First SELECT after BEGIN will establish the snapshot in REPEATABLE-READ.
2767                 // Get an estimate of the replica DB lag before then, treating estimate staleness
2768                 // as lag itself just to be safe
2769                 $status = $this->getApproximateLagStatus();
2770                 $this->mTrxReplicaLag = $status['lag'] + ( microtime( true ) - $status['since'] );
2771         }
2772
2773         /**
2774          * Issues the BEGIN command to the database server.
2775          *
2776          * @see DatabaseBase::begin()
2777          * @param string $fname
2778          */
2779         protected function doBegin( $fname ) {
2780                 $this->query( 'BEGIN', $fname );
2781                 $this->mTrxLevel = 1;
2782         }
2783
2784         final public function commit( $fname = __METHOD__, $flush = '' ) {
2785                 if ( $this->mTrxLevel && $this->mTrxAtomicLevels ) {
2786                         // There are still atomic sections open. This cannot be ignored
2787                         $levels = implode( ', ', $this->mTrxAtomicLevels );
2788                         throw new DBUnexpectedError(
2789                                 $this,
2790                                 "$fname: Got COMMIT while atomic sections $levels are still open."
2791                         );
2792                 }
2793
2794                 if ( $flush === self::FLUSHING_INTERNAL || $flush === self::FLUSHING_ALL_PEERS ) {
2795                         if ( !$this->mTrxLevel ) {
2796                                 return; // nothing to do
2797                         } elseif ( !$this->mTrxAutomatic ) {
2798                                 throw new DBUnexpectedError(
2799                                         $this,
2800                                         "$fname: Flushing an explicit transaction, getting out of sync."
2801                                 );
2802                         }
2803                 } else {
2804                         if ( !$this->mTrxLevel ) {
2805                                 $this->queryLogger->error(
2806                                         "$fname: No transaction to commit, something got out of sync." );
2807                                 return; // nothing to do
2808                         } elseif ( $this->mTrxAutomatic ) {
2809                                 // @TODO: make this an exception at some point
2810                                 $msg = "$fname: Explicit commit of implicit transaction.";
2811                                 $this->queryLogger->error( $msg );
2812                                 return; // wait for the main transaction set commit round
2813                         }
2814                 }
2815
2816                 // Avoid fatals if close() was called
2817                 $this->assertOpen();
2818
2819                 $this->runOnTransactionPreCommitCallbacks();
2820                 $writeTime = $this->pendingWriteQueryDuration( self::ESTIMATE_DB_APPLY );
2821                 $this->doCommit( $fname );
2822                 if ( $this->mTrxDoneWrites ) {
2823                         $this->mDoneWrites = microtime( true );
2824                         $this->trxProfiler->transactionWritingOut(
2825                                 $this->mServer, $this->mDBname, $this->mTrxShortId, $writeTime );
2826                 }
2827
2828                 $this->runOnTransactionIdleCallbacks( self::TRIGGER_COMMIT );
2829                 $this->runTransactionListenerCallbacks( self::TRIGGER_COMMIT );
2830         }
2831
2832         /**
2833          * Issues the COMMIT command to the database server.
2834          *
2835          * @see DatabaseBase::commit()
2836          * @param string $fname
2837          */
2838         protected function doCommit( $fname ) {
2839                 if ( $this->mTrxLevel ) {
2840                         $this->query( 'COMMIT', $fname );
2841                         $this->mTrxLevel = 0;
2842                 }
2843         }
2844
2845         final public function rollback( $fname = __METHOD__, $flush = '' ) {
2846                 if ( $flush === self::FLUSHING_INTERNAL || $flush === self::FLUSHING_ALL_PEERS ) {
2847                         if ( !$this->mTrxLevel ) {
2848                                 return; // nothing to do
2849                         }
2850                 } else {
2851                         if ( !$this->mTrxLevel ) {
2852                                 $this->queryLogger->error(
2853                                         "$fname: No transaction to rollback, something got out of sync." );
2854                                 return; // nothing to do
2855                         } elseif ( $this->getFlag( DBO_TRX ) ) {
2856                                 throw new DBUnexpectedError(
2857                                         $this,
2858                                         "$fname: Expected mass rollback of all peer databases (DBO_TRX set)."
2859                                 );
2860                         }
2861                 }
2862
2863                 // Avoid fatals if close() was called
2864                 $this->assertOpen();
2865
2866                 $this->doRollback( $fname );
2867                 $this->mTrxAtomicLevels = [];
2868                 if ( $this->mTrxDoneWrites ) {
2869                         $this->trxProfiler->transactionWritingOut(
2870                                 $this->mServer, $this->mDBname, $this->mTrxShortId );
2871                 }
2872
2873                 $this->mTrxIdleCallbacks = []; // clear
2874                 $this->mTrxPreCommitCallbacks = []; // clear
2875                 $this->runOnTransactionIdleCallbacks( self::TRIGGER_ROLLBACK );
2876                 $this->runTransactionListenerCallbacks( self::TRIGGER_ROLLBACK );
2877         }
2878
2879         /**
2880          * Issues the ROLLBACK command to the database server.
2881          *
2882          * @see DatabaseBase::rollback()
2883          * @param string $fname
2884          */
2885         protected function doRollback( $fname ) {
2886                 if ( $this->mTrxLevel ) {
2887                         # Disconnects cause rollback anyway, so ignore those errors
2888                         $ignoreErrors = true;
2889                         $this->query( 'ROLLBACK', $fname, $ignoreErrors );
2890                         $this->mTrxLevel = 0;
2891                 }
2892         }
2893
2894         public function flushSnapshot( $fname = __METHOD__ ) {
2895                 if ( $this->writesOrCallbacksPending() || $this->explicitTrxActive() ) {
2896                         // This only flushes transactions to clear snapshots, not to write data
2897                         $fnames = implode( ', ', $this->pendingWriteAndCallbackCallers() );
2898                         throw new DBUnexpectedError(
2899                                 $this,
2900                                 "$fname: Cannot COMMIT to clear snapshot because writes are pending ($fnames)."
2901                         );
2902                 }
2903
2904                 $this->commit( $fname, self::FLUSHING_INTERNAL );
2905         }
2906
2907         public function explicitTrxActive() {
2908                 return $this->mTrxLevel && ( $this->mTrxAtomicLevels || !$this->mTrxAutomatic );
2909         }
2910
2911         /**
2912          * Creates a new table with structure copied from existing table
2913          * Note that unlike most database abstraction functions, this function does not
2914          * automatically append database prefix, because it works at a lower
2915          * abstraction level.
2916          * The table names passed to this function shall not be quoted (this
2917          * function calls addIdentifierQuotes when needed).
2918          *
2919          * @param string $oldName Name of table whose structure should be copied
2920          * @param string $newName Name of table to be created
2921          * @param bool $temporary Whether the new table should be temporary
2922          * @param string $fname Calling function name
2923          * @throws RuntimeException
2924          * @return bool True if operation was successful
2925          */
2926         public function duplicateTableStructure( $oldName, $newName, $temporary = false,
2927                 $fname = __METHOD__
2928         ) {
2929                 throw new RuntimeException( __METHOD__ . ' is not implemented in descendant class' );
2930         }
2931
2932         public function listTables( $prefix = null, $fname = __METHOD__ ) {
2933                 throw new RuntimeException( __METHOD__ . ' is not implemented in descendant class' );
2934         }
2935
2936         /**
2937          * Reset the views process cache set by listViews()
2938          * @since 1.22
2939          */
2940         final public function clearViewsCache() {
2941                 $this->allViews = null;
2942         }
2943
2944         /**
2945          * Lists all the VIEWs in the database
2946          *
2947          * For caching purposes the list of all views should be stored in
2948          * $this->allViews. The process cache can be cleared with clearViewsCache()
2949          *
2950          * @param string $prefix Only show VIEWs with this prefix, eg. unit_test_
2951          * @param string $fname Name of calling function
2952          * @throws RuntimeException
2953          * @return array
2954          * @since 1.22
2955          */
2956         public function listViews( $prefix = null, $fname = __METHOD__ ) {
2957                 throw new RuntimeException( __METHOD__ . ' is not implemented in descendant class' );
2958         }
2959
2960         /**
2961          * Differentiates between a TABLE and a VIEW
2962          *
2963          * @param string $name Name of the database-structure to test.
2964          * @throws RuntimeException
2965          * @return bool
2966          * @since 1.22
2967          */
2968         public function isView( $name ) {
2969                 throw new RuntimeException( __METHOD__ . ' is not implemented in descendant class' );
2970         }
2971
2972         public function timestamp( $ts = 0 ) {
2973                 $t = new ConvertibleTimestamp( $ts );
2974                 // Let errors bubble up to avoid putting garbage in the DB
2975                 return $t->getTimestamp( TS_MW );
2976         }
2977
2978         public function timestampOrNull( $ts = null ) {
2979                 if ( is_null( $ts ) ) {
2980                         return null;
2981                 } else {
2982                         return $this->timestamp( $ts );
2983                 }
2984         }
2985
2986         /**
2987          * Take the result from a query, and wrap it in a ResultWrapper if
2988          * necessary. Boolean values are passed through as is, to indicate success
2989          * of write queries or failure.
2990          *
2991          * Once upon a time, DatabaseBase::query() returned a bare MySQL result
2992          * resource, and it was necessary to call this function to convert it to
2993          * a wrapper. Nowadays, raw database objects are never exposed to external
2994          * callers, so this is unnecessary in external code.
2995          *
2996          * @param bool|ResultWrapper|resource|object $result
2997          * @return bool|ResultWrapper
2998          */
2999         protected function resultObject( $result ) {
3000                 if ( !$result ) {
3001                         return false;
3002                 } elseif ( $result instanceof ResultWrapper ) {
3003                         return $result;
3004                 } elseif ( $result === true ) {
3005                         // Successful write query
3006                         return $result;
3007                 } else {
3008                         return new ResultWrapper( $this, $result );
3009                 }
3010         }
3011
3012         public function ping( &$rtt = null ) {
3013                 // Avoid hitting the server if it was hit recently
3014                 if ( $this->isOpen() && ( microtime( true ) - $this->lastPing ) < self::PING_TTL ) {
3015                         if ( !func_num_args() || $this->mRTTEstimate > 0 ) {
3016                                 $rtt = $this->mRTTEstimate;
3017                                 return true; // don't care about $rtt
3018                         }
3019                 }
3020
3021                 // This will reconnect if possible or return false if not
3022                 $this->clearFlag( DBO_TRX, self::REMEMBER_PRIOR );
3023                 $ok = ( $this->query( self::PING_QUERY, __METHOD__, true ) !== false );
3024                 $this->restoreFlags( self::RESTORE_PRIOR );
3025
3026                 if ( $ok ) {
3027                         $rtt = $this->mRTTEstimate;
3028                 }
3029
3030                 return $ok;
3031         }
3032
3033         /**
3034          * @return bool
3035          */
3036         protected function reconnect() {
3037                 $this->closeConnection();
3038                 $this->mOpened = false;
3039                 $this->mConn = false;
3040                 try {
3041                         $this->open( $this->mServer, $this->mUser, $this->mPassword, $this->mDBname );
3042                         $this->lastPing = microtime( true );
3043                         $ok = true;
3044                 } catch ( DBConnectionError $e ) {
3045                         $ok = false;
3046                 }
3047
3048                 return $ok;
3049         }
3050
3051         public function getSessionLagStatus() {
3052                 return $this->getTransactionLagStatus() ?: $this->getApproximateLagStatus();
3053         }
3054
3055         /**
3056          * Get the replica DB lag when the current transaction started
3057          *
3058          * This is useful when transactions might use snapshot isolation
3059          * (e.g. REPEATABLE-READ in innodb), so the "real" lag of that data
3060          * is this lag plus transaction duration. If they don't, it is still
3061          * safe to be pessimistic. This returns null if there is no transaction.
3062          *
3063          * @return array|null ('lag': seconds or false on error, 'since': UNIX timestamp of BEGIN)
3064          * @since 1.27
3065          */
3066         protected function getTransactionLagStatus() {
3067                 return $this->mTrxLevel
3068                         ? [ 'lag' => $this->mTrxReplicaLag, 'since' => $this->trxTimestamp() ]
3069                         : null;
3070         }
3071
3072         /**
3073          * Get a replica DB lag estimate for this server
3074          *
3075          * @return array ('lag': seconds or false on error, 'since': UNIX timestamp of estimate)
3076          * @since 1.27
3077          */
3078         protected function getApproximateLagStatus() {
3079                 return [
3080                         'lag'   => $this->getLBInfo( 'replica' ) ? $this->getLag() : 0,
3081                         'since' => microtime( true )
3082                 ];
3083         }
3084
3085         /**
3086          * Merge the result of getSessionLagStatus() for several DBs
3087          * using the most pessimistic values to estimate the lag of
3088          * any data derived from them in combination
3089          *
3090          * This is information is useful for caching modules
3091          *
3092          * @see WANObjectCache::set()
3093          * @see WANObjectCache::getWithSetCallback()
3094          *
3095          * @param IDatabase $db1
3096          * @param IDatabase ...
3097          * @return array Map of values:
3098          *   - lag: highest lag of any of the DBs or false on error (e.g. replication stopped)
3099          *   - since: oldest UNIX timestamp of any of the DB lag estimates
3100          *   - pending: whether any of the DBs have uncommitted changes
3101          * @since 1.27
3102          */
3103         public static function getCacheSetOptions( IDatabase $db1 ) {
3104                 $res = [ 'lag' => 0, 'since' => INF, 'pending' => false ];
3105                 foreach ( func_get_args() as $db ) {
3106                         /** @var IDatabase $db */
3107                         $status = $db->getSessionLagStatus();
3108                         if ( $status['lag'] === false ) {
3109                                 $res['lag'] = false;
3110                         } elseif ( $res['lag'] !== false ) {
3111                                 $res['lag'] = max( $res['lag'], $status['lag'] );
3112                         }
3113                         $res['since'] = min( $res['since'], $status['since'] );
3114                         $res['pending'] = $res['pending'] ?: $db->writesPending();
3115                 }
3116
3117                 return $res;
3118         }
3119
3120         public function getLag() {
3121                 return 0;
3122         }
3123
3124         public function maxListLen() {
3125                 return 0;
3126         }
3127
3128         public function encodeBlob( $b ) {
3129                 return $b;
3130         }
3131
3132         public function decodeBlob( $b ) {
3133                 if ( $b instanceof Blob ) {
3134                         $b = $b->fetch();
3135                 }
3136                 return $b;
3137         }
3138
3139         public function setSessionOptions( array $options ) {
3140         }
3141
3142         /**
3143          * Read and execute SQL commands from a file.
3144          *
3145          * Returns true on success, error string or exception on failure (depending
3146          * on object's error ignore settings).
3147          *
3148          * @param string $filename File name to open
3149          * @param bool|callable $lineCallback Optional function called before reading each line
3150          * @param bool|callable $resultCallback Optional function called for each MySQL result
3151          * @param bool|string $fname Calling function name or false if name should be
3152          *   generated dynamically using $filename
3153          * @param bool|callable $inputCallback Optional function called for each
3154          *   complete line sent
3155          * @return bool|string
3156          * @throws Exception
3157          */
3158         public function sourceFile(
3159                 $filename,
3160                 $lineCallback = false,
3161                 $resultCallback = false,
3162                 $fname = false,
3163                 $inputCallback = false
3164         ) {
3165                 MediaWiki\suppressWarnings();
3166                 $fp = fopen( $filename, 'r' );
3167                 MediaWiki\restoreWarnings();
3168
3169                 if ( false === $fp ) {
3170                         throw new RuntimeException( "Could not open \"{$filename}\".\n" );
3171                 }
3172
3173                 if ( !$fname ) {
3174                         $fname = __METHOD__ . "( $filename )";
3175                 }
3176
3177                 try {
3178                         $error = $this->sourceStream(
3179                                 $fp, $lineCallback, $resultCallback, $fname, $inputCallback );
3180                 } catch ( Exception $e ) {
3181                         fclose( $fp );
3182                         throw $e;
3183                 }
3184
3185                 fclose( $fp );
3186
3187                 return $error;
3188         }
3189
3190         public function setSchemaVars( $vars ) {
3191                 $this->mSchemaVars = $vars;
3192         }
3193
3194         /**
3195          * Read and execute commands from an open file handle.
3196          *
3197          * Returns true on success, error string or exception on failure (depending
3198          * on object's error ignore settings).
3199          *
3200          * @param resource $fp File handle
3201          * @param bool|callable $lineCallback Optional function called before reading each query
3202          * @param bool|callable $resultCallback Optional function called for each MySQL result
3203          * @param string $fname Calling function name
3204          * @param bool|callable $inputCallback Optional function called for each complete query sent
3205          * @return bool|string
3206          */
3207         public function sourceStream(
3208                 $fp,
3209                 $lineCallback = false,
3210                 $resultCallback = false,
3211                 $fname = __METHOD__,
3212                 $inputCallback = false
3213         ) {
3214                 $cmd = '';
3215
3216                 while ( !feof( $fp ) ) {
3217                         if ( $lineCallback ) {
3218                                 call_user_func( $lineCallback );
3219                         }
3220
3221                         $line = trim( fgets( $fp ) );
3222
3223                         if ( $line == '' ) {
3224                                 continue;
3225                         }
3226
3227                         if ( '-' == $line[0] && '-' == $line[1] ) {
3228                                 continue;
3229                         }
3230
3231                         if ( $cmd != '' ) {
3232                                 $cmd .= ' ';
3233                         }
3234
3235                         $done = $this->streamStatementEnd( $cmd, $line );
3236
3237                         $cmd .= "$line\n";
3238
3239                         if ( $done || feof( $fp ) ) {
3240                                 $cmd = $this->replaceVars( $cmd );
3241
3242                                 if ( !$inputCallback || call_user_func( $inputCallback, $cmd ) ) {
3243                                         $res = $this->query( $cmd, $fname );
3244
3245                                         if ( $resultCallback ) {
3246                                                 call_user_func( $resultCallback, $res, $this );
3247                                         }
3248
3249                                         if ( false === $res ) {
3250                                                 $err = $this->lastError();
3251
3252                                                 return "Query \"{$cmd}\" failed with error code \"$err\".\n";
3253                                         }
3254                                 }
3255                                 $cmd = '';
3256                         }
3257                 }
3258
3259                 return true;
3260         }
3261
3262         /**
3263          * Called by sourceStream() to check if we've reached a statement end
3264          *
3265          * @param string &$sql SQL assembled so far
3266          * @param string &$newLine New line about to be added to $sql
3267          * @return bool Whether $newLine contains end of the statement
3268          */
3269         public function streamStatementEnd( &$sql, &$newLine ) {
3270                 if ( $this->delimiter ) {
3271                         $prev = $newLine;
3272                         $newLine = preg_replace(
3273                                 '/' . preg_quote( $this->delimiter, '/' ) . '$/', '', $newLine );
3274                         if ( $newLine != $prev ) {
3275                                 return true;
3276                         }
3277                 }
3278
3279                 return false;
3280         }
3281
3282         /**
3283          * Database independent variable replacement. Replaces a set of variables
3284          * in an SQL statement with their contents as given by $this->getSchemaVars().
3285          *
3286          * Supports '{$var}' `{$var}` and / *$var* / (without the spaces) style variables.
3287          *
3288          * - '{$var}' should be used for text and is passed through the database's
3289          *   addQuotes method.
3290          * - `{$var}` should be used for identifiers (e.g. table and database names).
3291          *   It is passed through the database's addIdentifierQuotes method which
3292          *   can be overridden if the database uses something other than backticks.
3293          * - / *_* / or / *$wgDBprefix* / passes the name that follows through the
3294          *   database's tableName method.
3295          * - / *i* / passes the name that follows through the database's indexName method.
3296          * - In all other cases, / *$var* / is left unencoded. Except for table options,
3297          *   its use should be avoided. In 1.24 and older, string encoding was applied.
3298          *
3299          * @param string $ins SQL statement to replace variables in
3300          * @return string The new SQL statement with variables replaced
3301          */
3302         protected function replaceVars( $ins ) {
3303                 $vars = $this->getSchemaVars();
3304                 return preg_replace_callback(
3305                         '!
3306                                 /\* (\$wgDBprefix|[_i]) \*/ (\w*) | # 1-2. tableName, indexName
3307                                 \'\{\$ (\w+) }\'                  | # 3. addQuotes
3308                                 `\{\$ (\w+) }`                    | # 4. addIdentifierQuotes
3309                                 /\*\$ (\w+) \*/                     # 5. leave unencoded
3310                         !x',
3311                         function ( $m ) use ( $vars ) {
3312                                 // Note: Because of <https://bugs.php.net/bug.php?id=51881>,
3313                                 // check for both nonexistent keys *and* the empty string.
3314                                 if ( isset( $m[1] ) && $m[1] !== '' ) {
3315                                         if ( $m[1] === 'i' ) {
3316                                                 return $this->indexName( $m[2] );
3317                                         } else {
3318                                                 return $this->tableName( $m[2] );
3319                                         }
3320                                 } elseif ( isset( $m[3] ) && $m[3] !== '' && array_key_exists( $m[3], $vars ) ) {
3321                                         return $this->addQuotes( $vars[$m[3]] );
3322                                 } elseif ( isset( $m[4] ) && $m[4] !== '' && array_key_exists( $m[4], $vars ) ) {
3323                                         return $this->addIdentifierQuotes( $vars[$m[4]] );
3324                                 } elseif ( isset( $m[5] ) && $m[5] !== '' && array_key_exists( $m[5], $vars ) ) {
3325                                         return $vars[$m[5]];
3326                                 } else {
3327                                         return $m[0];
3328                                 }
3329                         },
3330                         $ins
3331                 );
3332         }
3333
3334         /**
3335          * Get schema variables. If none have been set via setSchemaVars(), then
3336          * use some defaults from the current object.
3337          *
3338          * @return array
3339          */
3340         protected function getSchemaVars() {
3341                 if ( $this->mSchemaVars ) {
3342                         return $this->mSchemaVars;
3343                 } else {
3344                         return $this->getDefaultSchemaVars();
3345                 }
3346         }
3347
3348         /**
3349          * Get schema variables to use if none have been set via setSchemaVars().
3350          *
3351          * Override this in derived classes to provide variables for tables.sql
3352          * and SQL patch files.
3353          *
3354          * @return array
3355          */
3356         protected function getDefaultSchemaVars() {
3357                 return [];
3358         }
3359
3360         public function lockIsFree( $lockName, $method ) {
3361                 return true;
3362         }
3363
3364         public function lock( $lockName, $method, $timeout = 5 ) {
3365                 $this->mNamedLocksHeld[$lockName] = 1;
3366
3367                 return true;
3368         }
3369
3370         public function unlock( $lockName, $method ) {
3371                 unset( $this->mNamedLocksHeld[$lockName] );
3372
3373                 return true;
3374         }
3375
3376         public function getScopedLockAndFlush( $lockKey, $fname, $timeout ) {
3377                 if ( $this->writesOrCallbacksPending() ) {
3378                         // This only flushes transactions to clear snapshots, not to write data
3379                         $fnames = implode( ', ', $this->pendingWriteAndCallbackCallers() );
3380                         throw new DBUnexpectedError(
3381                                 $this,
3382                                 "$fname: Cannot COMMIT to clear snapshot because writes are pending ($fnames)."
3383                         );
3384                 }
3385
3386                 if ( !$this->lock( $lockKey, $fname, $timeout ) ) {
3387                         return null;
3388                 }
3389
3390                 $unlocker = new ScopedCallback( function () use ( $lockKey, $fname ) {
3391                         if ( $this->trxLevel() ) {
3392                                 // There is a good chance an exception was thrown, causing any early return
3393                                 // from the caller. Let any error handler get a chance to issue rollback().
3394                                 // If there isn't one, let the error bubble up and trigger server-side rollback.
3395                                 $this->onTransactionResolution(
3396                                         function () use ( $lockKey, $fname ) {
3397                                                 $this->unlock( $lockKey, $fname );
3398                                         },
3399                                         $fname
3400                                 );
3401                         } else {
3402                                 $this->unlock( $lockKey, $fname );
3403                         }
3404                 } );
3405
3406                 $this->commit( $fname, self::FLUSHING_INTERNAL );
3407
3408                 return $unlocker;
3409         }
3410
3411         public function namedLocksEnqueue() {
3412                 return false;
3413         }
3414
3415         /**
3416          * Lock specific tables
3417          *
3418          * @param array $read Array of tables to lock for read access
3419          * @param array $write Array of tables to lock for write access
3420          * @param string $method Name of caller
3421          * @param bool $lowPriority Whether to indicate writes to be LOW PRIORITY
3422          * @return bool
3423          */
3424         public function lockTables( $read, $write, $method, $lowPriority = true ) {
3425                 return true;
3426         }
3427
3428         /**
3429          * Unlock specific tables
3430          *
3431          * @param string $method The caller
3432          * @return bool
3433          */
3434         public function unlockTables( $method ) {
3435                 return true;
3436         }
3437
3438         /**
3439          * Delete a table
3440          * @param string $tableName
3441          * @param string $fName
3442          * @return bool|ResultWrapper
3443          * @since 1.18
3444          */
3445         public function dropTable( $tableName, $fName = __METHOD__ ) {
3446                 if ( !$this->tableExists( $tableName, $fName ) ) {
3447                         return false;
3448                 }
3449                 $sql = "DROP TABLE " . $this->tableName( $tableName ) . " CASCADE";
3450
3451                 return $this->query( $sql, $fName );
3452         }
3453
3454         public function getInfinity() {
3455                 return 'infinity';
3456         }
3457
3458         public function encodeExpiry( $expiry ) {
3459                 return ( $expiry == '' || $expiry == 'infinity' || $expiry == $this->getInfinity() )
3460                         ? $this->getInfinity()
3461                         : $this->timestamp( $expiry );
3462         }
3463
3464         public function decodeExpiry( $expiry, $format = TS_MW ) {
3465                 if ( $expiry == '' || $expiry == 'infinity' || $expiry == $this->getInfinity() ) {
3466                         return 'infinity';
3467                 }
3468
3469                 return ConvertibleTimestamp::convert( $format, $expiry );
3470         }
3471
3472         public function setBigSelects( $value = true ) {
3473                 // no-op
3474         }
3475
3476         public function isReadOnly() {
3477                 return ( $this->getReadOnlyReason() !== false );
3478         }
3479
3480         /**
3481          * @return string|bool Reason this DB is read-only or false if it is not
3482          */
3483         protected function getReadOnlyReason() {
3484                 $reason = $this->getLBInfo( 'readOnlyReason' );
3485
3486                 return is_string( $reason ) ? $reason : false;
3487         }
3488
3489         public function setTableAliases( array $aliases ) {
3490                 $this->tableAliases = $aliases;
3491         }
3492
3493         /**
3494          * @return bool Whether a DB user is required to access the DB
3495          * @since 1.28
3496          */
3497         protected function requiresDatabaseUser() {
3498                 return true;
3499         }
3500
3501         /**
3502          * @since 1.19
3503          * @return string
3504          */
3505         public function __toString() {
3506                 return (string)$this->mConn;
3507         }
3508
3509         /**
3510          * Make sure that copies do not share the same client binding handle
3511          * @throws DBConnectionError
3512          */
3513         public function __clone() {
3514                 $this->connLogger->warning(
3515                         "Cloning " . get_class( $this ) . " is not recomended; forking connection:\n" .
3516                         ( new RuntimeException() )->getTraceAsString()
3517                 );
3518
3519                 if ( $this->isOpen() ) {
3520                         // Open a new connection resource without messing with the old one
3521                         $this->mOpened = false;
3522                         $this->mConn = false;
3523                         $this->mTrxEndCallbacks = []; // don't copy
3524                         $this->handleSessionLoss(); // no trx or locks anymore
3525                         $this->open( $this->mServer, $this->mUser, $this->mPassword, $this->mDBname );
3526                         $this->lastPing = microtime( true );
3527                 }
3528         }
3529
3530         /**
3531          * Called by serialize. Throw an exception when DB connection is serialized.
3532          * This causes problems on some database engines because the connection is
3533          * not restored on unserialize.
3534          */
3535         public function __sleep() {
3536                 throw new RuntimeException( 'Database serialization may cause problems, since ' .
3537                         'the connection is not restored on wakeup.' );
3538         }
3539
3540         /**
3541          * Run a few simple sanity checks and close dangling connections
3542          */
3543         public function __destruct() {
3544                 if ( $this->mTrxLevel && $this->mTrxDoneWrites ) {
3545                         trigger_error( "Uncommitted DB writes (transaction from {$this->mTrxFname})." );
3546                 }
3547
3548                 $danglingWriters = $this->pendingWriteAndCallbackCallers();
3549                 if ( $danglingWriters ) {
3550                         $fnames = implode( ', ', $danglingWriters );
3551                         trigger_error( "DB transaction writes or callbacks still pending ($fnames)." );
3552                 }
3553
3554                 if ( $this->mConn ) {
3555                         // Avoid connection leaks for sanity
3556                         $this->closeConnection();
3557                         $this->mConn = false;
3558                         $this->mOpened = false;
3559                 }
3560         }
3561 }