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