includes/libs/rdbms/database/Database.php

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