includes/libs/rdbms/database/Database.php

   1 <?php
   2 /**
   3  * @defgroup Database Database
   4  *
   5  * This file deals with database interface functions
   6  * and query specifics/optimisations.
   7  *
   8  * This program is free software; you can redistribute it and/or modify
   9  * it under the terms of the GNU General Public License as published by
  10  * the Free Software Foundation; either version 2 of the License, or
  11  * (at your option) any later version.
  12  *
  13  * This program is distributed in the hope that it will be useful,
  14  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  15  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
  16  * GNU General Public License for more details.
  17  *
  18  * You should have received a copy of the GNU General Public License along
  19  * with this program; if not, write to the Free Software Foundation, Inc.,
  20  * 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
  21  * http://www.gnu.org/copyleft/gpl.html
  22  *
  23  * @file
  24  * @ingroup Database
  25  */
  26 use Psr\Log\LoggerAwareInterface;
  27 use Psr\Log\LoggerInterface;
  28
  29 /**
  30  * Relational database abstraction object
  31  *
  32  * @ingroup Database
  33  * @since 1.28
  34  */
  35 abstract class Database implements IDatabase, IMaintainableDatabase, LoggerAwareInterface {
  36         /** Number of times to re-try an operation in case of deadlock */
  37         const DEADLOCK_TRIES = 4;
  38         /** Minimum time to wait before retry, in microseconds */
  39         const DEADLOCK_DELAY_MIN = 500000;
  40         /** Maximum time to wait before retry */
  41         const DEADLOCK_DELAY_MAX = 1500000;
  42
  43         /** How long before it is worth doing a dummy query to test the connection */
  44         const PING_TTL = 1.0;
  45         const PING_QUERY = 'SELECT 1 AS ping';
  46
  47         const TINY_WRITE_SEC = .010;
  48         const SLOW_WRITE_SEC = .500;
  49         const SMALL_WRITE_ROWS = 100;
  50
  51         /** @var string SQL query */
  52         protected $mLastQuery = '';
  53         /** @var bool */
  54         protected $mDoneWrites = false;
  55         /** @var string|bool */
  56         protected $mPHPError = false;
  57         /** @var string */
  58         protected $mServer;
  59         /** @var string */
  60         protected $mUser;
  61         /** @var string */
  62         protected $mPassword;
  63         /** @var string */
  64         protected $mDBname;
  65         /** @var array[] $aliases Map of (table => (dbname, schema, prefix) map) */
  66         protected $tableAliases = [];
  67         /** @var bool Whether this PHP instance is for a CLI script */
  68         protected $cliMode;
  69         /** @var string Agent name for query profiling */
  70         protected $agent;
  71
  72         /** @var BagOStuff APC cache */
  73         protected $srvCache;
  74         /** @var LoggerInterface */
  75         protected $connLogger;
  76         /** @var LoggerInterface */
  77         protected $queryLogger;
  78         /** @var callback Error logging callback */
  79         protected $errorLogger;
  80
  81         /** @var resource Database connection */
  82         protected $mConn = null;
  83         /** @var bool */
  84         protected $mOpened = false;
  85
  86         /** @var array[] List of (callable, method name) */
  87         protected $mTrxIdleCallbacks = [];
  88         /** @var array[] List of (callable, method name) */
  89         protected $mTrxPreCommitCallbacks = [];
  90         /** @var array[] List of (callable, method name) */
  91         protected $mTrxEndCallbacks = [];
  92         /** @var callable[] Map of (name => callable) */
  93         protected $mTrxRecurringCallbacks = [];
  94         /** @var bool Whether to suppress triggering of transaction end callbacks */
  95         protected $mTrxEndCallbacksSuppressed = false;
  96
  97         /** @var string */
  98         protected $mTablePrefix = '';
  99         /** @var string */
 100         protected $mSchema = '';
 101         /** @var integer */
 102         protected $mFlags;
 103         /** @var array */
 104         protected $mLBInfo = [];
 105         /** @var bool|null */
 106         protected $mDefaultBigSelects = null;
 107         /** @var array|bool */
 108         protected $mSchemaVars = false;
 109         /** @var array */
 110         protected $mSessionVars = [];
 111         /** @var array|null */
 112         protected $preparedArgs;
 113         /** @var string|bool|null Stashed value of html_errors INI setting */
 114         protected $htmlErrors;
 115         /** @var string */
 116         protected $delimiter = ';';
 117         /** @var DatabaseDomain */
 118         protected $currentDomain;
 119
 120         /**
 121          * Either 1 if a transaction is active or 0 otherwise.
 122          * The other Trx fields may not be meaningfull if this is 0.
 123          *
 124          * @var int
 125          */
 126         protected $mTrxLevel = 0;
 127         /**
 128          * Either a short hexidecimal string if a transaction is active or ""
 129          *
 130          * @var string
 131          * @see Database::mTrxLevel
 132          */
 133         protected $mTrxShortId = '';
 134         /**
 135          * The UNIX time that the transaction started. Callers can assume that if
 136          * snapshot isolation is used, then the data is *at least* up to date to that
 137          * point (possibly more up-to-date since the first SELECT defines the snapshot).
 138          *
 139          * @var float|null
 140          * @see Database::mTrxLevel
 141          */
 142         private $mTrxTimestamp = null;
 143         /** @var float Lag estimate at the time of BEGIN */
 144         private $mTrxReplicaLag = null;
 145         /**
 146          * Remembers the function name given for starting the most recent transaction via begin().
 147          * Used to provide additional context for error reporting.
 148          *
 149          * @var string
 150          * @see Database::mTrxLevel
 151          */
 152         private $mTrxFname = null;
 153         /**
 154          * Record if possible write queries were done in the last transaction started
 155          *
 156          * @var bool
 157          * @see Database::mTrxLevel
 158          */
 159         private $mTrxDoneWrites = false;
 160         /**
 161          * Record if the current transaction was started implicitly due to DBO_TRX being set.
 162          *
 163          * @var bool
 164          * @see Database::mTrxLevel
 165          */
 166         private $mTrxAutomatic = false;
 167         /**
 168          * Array of levels of atomicity within transactions
 169          *
 170          * @var array
 171          */
 172         private $mTrxAtomicLevels = [];
 173         /**
 174          * Record if the current transaction was started implicitly by Database::startAtomic
 175          *
 176          * @var bool
 177          */
 178         private $mTrxAutomaticAtomic = false;
 179         /**
 180          * Track the write query callers of the current transaction
 181          *
 182          * @var string[]
 183          */
 184         private $mTrxWriteCallers = [];
 185         /**
 186          * @var float Seconds spent in write queries for the current transaction
 187          */
 188         private $mTrxWriteDuration = 0.0;
 189         /**
 190          * @var integer Number of write queries for the current transaction
 191          */
 192         private $mTrxWriteQueryCount = 0;
 193         /**
 194          * @var float Like mTrxWriteQueryCount but excludes lock-bound, easy to replicate, queries
 195          */
 196         private $mTrxWriteAdjDuration = 0.0;
 197         /**
 198          * @var integer Number of write queries counted in mTrxWriteAdjDuration
 199          */
 200         private $mTrxWriteAdjQueryCount = 0;
 201         /**
 202          * @var float RTT time estimate
 203          */
 204         private $mRTTEstimate = 0.0;
 205
 206         /** @var array Map of (name => 1) for locks obtained via lock() */
 207         private $mNamedLocksHeld = [];
 208         /** @var array Map of (table name => 1) for TEMPORARY tables */
 209         protected $mSessionTempTables = [];
 210
 211         /** @var IDatabase|null Lazy handle to the master DB this server replicates from */
 212         private $lazyMasterHandle;
 213
 214         /** @var float UNIX timestamp */
 215         protected $lastPing = 0.0;
 216
 217         /** @var int[] Prior mFlags values */
 218         private $priorFlags = [];
 219
 220         /** @var object|string Class name or object With profileIn/profileOut methods */
 221         protected $profiler;
 222         /** @var TransactionProfiler */
 223         protected $trxProfiler;
 224
 225         /**
 226          * Constructor and database handle and attempt to connect to the DB server
 227          *
 228          * IDatabase classes should not be constructed directly in external
 229          * code. Database::factory() should be used instead.
 230          *
 231          * @param array $params Parameters passed from Database::factory()
 232          */
 233         function __construct( array $params ) {
 234                 $server = $params['host'];
 235                 $user = $params['user'];
 236                 $password = $params['password'];
 237                 $dbName = $params['dbname'];
 238
 239                 $this->mSchema = $params['schema'];
 240                 $this->mTablePrefix = $params['tablePrefix'];
 241
 242                 $this->cliMode = $params['cliMode'];
 243                 // Agent name is added to SQL queries in a comment, so make sure it can't break out
 244                 $this->agent = str_replace( '/', '-', $params['agent'] );
 245
 246                 $this->mFlags = $params['flags'];
 247                 if ( $this->mFlags & self::DBO_DEFAULT ) {
 248                         if ( $this->cliMode ) {
 249                                 $this->mFlags &= ~self::DBO_TRX;
 250                         } else {
 251                                 $this->mFlags |= self::DBO_TRX;
 252                         }
 253                 }
 254
 255                 $this->mSessionVars = $params['variables'];
 256
 257                 $this->srvCache = isset( $params['srvCache'] )
 258                         ? $params['srvCache']
 259                         : new HashBagOStuff();
 260
 261                 $this->profiler = $params['profiler'];
 262                 $this->trxProfiler = $params['trxProfiler'];
 263                 $this->connLogger = $params['connLogger'];
 264                 $this->queryLogger = $params['queryLogger'];
 265                 $this->errorLogger = $params['errorLogger'];
 266
 267                 // Set initial dummy domain until open() sets the final DB/prefix
 268                 $this->currentDomain = DatabaseDomain::newUnspecified();
 269
 270                 if ( $user ) {
 271                         $this->open( $server, $user, $password, $dbName );
 272                 } elseif ( $this->requiresDatabaseUser() ) {
 273                         throw new InvalidArgumentException( "No database user provided." );
 274                 }
 275
 276                 // Set the domain object after open() sets the relevant fields
 277                 if ( $this->mDBname != '' ) {
 278                         // Domains with server scope but a table prefix are not used by IDatabase classes
 279                         $this->currentDomain = new DatabaseDomain( $this->mDBname, null, $this->mTablePrefix );
 280                 }
 281         }
 282
 283         /**
 284          * Construct a Database subclass instance given a database type and parameters
 285          *
 286          * This also connects to the database immediately upon object construction
 287          *
 288          * @param string $dbType A possible DB type (sqlite, mysql, postgres)
 289          * @param array $p Parameter map with keys:
 290          *   - host : The hostname of the DB server
 291          *   - user : The name of the database user the client operates under
 292          *   - password : The password for the database user
 293          *   - dbname : The name of the database to use where queries do not specify one.
 294          *      The database must exist or an error might be thrown. Setting this to the empty string
 295          *      will avoid any such errors and make the handle have no implicit database scope. This is
 296          *      useful for queries like SHOW STATUS, CREATE DATABASE, or DROP DATABASE. Note that a
 297          *      "database" in Postgres is rougly equivalent to an entire MySQL server. This the domain
 298          *      in which user names and such are defined, e.g. users are database-specific in Postgres.
 299          *   - schema : The database schema to use (if supported). A "schema" in Postgres is roughly
 300          *      equivalent to a "database" in MySQL. Note that MySQL and SQLite do not use schemas.
 301          *   - tablePrefix : Optional table prefix that is implicitly added on to all table names
 302          *      recognized in queries. This can be used in place of schemas for handle site farms.
 303          *   - flags : Optional bitfield of DBO_* constants that define connection, protocol,
 304          *      buffering, and transaction behavior. It is STRONGLY adviced to leave the DBO_DEFAULT
 305          *      flag in place UNLESS this this database simply acts as a key/value store.
 306          *   - driver: Optional name of a specific DB client driver. For MySQL, there is the old
 307          *      'mysql' driver and the newer 'mysqli' driver.
 308          *   - variables: Optional map of session variables to set after connecting. This can be
 309          *      used to adjust lock timeouts or encoding modes and the like.
 310          *   - connLogger: Optional PSR-3 logger interface instance.
 311          *   - queryLogger: Optional PSR-3 logger interface instance.
 312          *   - profiler: Optional class name or object with profileIn()/profileOut() methods.
 313          *      These will be called in query(), using a simplified version of the SQL that also
 314          *      includes the agent as a SQL comment.
 315          *   - trxProfiler: Optional TransactionProfiler instance.
 316          *   - errorLogger: Optional callback that takes an Exception and logs it.
 317          *   - cliMode: Whether to consider the execution context that of a CLI script.
 318          *   - agent: Optional name used to identify the end-user in query profiling/logging.
 319          *   - srvCache: Optional BagOStuff instance to an APC-style cache.
 320          * @return Database|null If the database driver or extension cannot be found
 321          * @throws InvalidArgumentException If the database driver or extension cannot be found
 322          * @since 1.18
 323          */
 324         final public static function factory( $dbType, $p = [] ) {
 325                 static $canonicalDBTypes = [
 326                         'mysql' => [ 'mysqli', 'mysql' ],
 327                         'postgres' => [],
 328                         'sqlite' => [],
 329                         'oracle' => [],
 330                         'mssql' => [],
 331                 ];
 332
 333                 $driver = false;
 334                 $dbType = strtolower( $dbType );
 335                 if ( isset( $canonicalDBTypes[$dbType] ) && $canonicalDBTypes[$dbType] ) {
 336                         $possibleDrivers = $canonicalDBTypes[$dbType];
 337                         if ( !empty( $p['driver'] ) ) {
 338                                 if ( in_array( $p['driver'], $possibleDrivers ) ) {
 339                                         $driver = $p['driver'];
 340                                 } else {
 341                                         throw new InvalidArgumentException( __METHOD__ .
 342                                                 " type '$dbType' does not support driver '{$p['driver']}'" );
 343                                 }
 344                         } else {
 345                                 foreach ( $possibleDrivers as $posDriver ) {
 346                                         if ( extension_loaded( $posDriver ) ) {
 347                                                 $driver = $posDriver;
 348                                                 break;
 349                                         }
 350                                 }
 351                         }
 352                 } else {
 353                         $driver = $dbType;
 354                 }
 355                 if ( $driver === false || $driver === '' ) {
 356                         throw new InvalidArgumentException( __METHOD__ .
 357                                 " no viable database extension found for type '$dbType'" );
 358                 }
 359
 360                 $class = 'Database' . ucfirst( $driver );
 361                 if ( class_exists( $class ) && is_subclass_of( $class, 'IDatabase' ) ) {
 362                         // Resolve some defaults for b/c
 363                         $p['host'] = isset( $p['host'] ) ? $p['host'] : false;
 364                         $p['user'] = isset( $p['user'] ) ? $p['user'] : false;
 365                         $p['password'] = isset( $p['password'] ) ? $p['password'] : false;
 366                         $p['dbname'] = isset( $p['dbname'] ) ? $p['dbname'] : false;
 367                         $p['flags'] = isset( $p['flags'] ) ? $p['flags'] : 0;
 368                         $p['variables'] = isset( $p['variables'] ) ? $p['variables'] : [];
 369                         $p['tablePrefix'] = isset( $p['tablePrefix'] ) ? $p['tablePrefix'] : '';
 370                         $p['schema'] = isset( $p['schema'] ) ? $p['schema'] : '';
 371                         $p['cliMode'] = isset( $p['cliMode'] ) ? $p['cliMode'] : ( PHP_SAPI === 'cli' );
 372                         $p['agent'] = isset( $p['agent'] ) ? $p['agent'] : '';
 373                         if ( !isset( $p['connLogger'] ) ) {
 374                                 $p['connLogger'] = new \Psr\Log\NullLogger();
 375                         }
 376                         if ( !isset( $p['queryLogger'] ) ) {
 377                                 $p['queryLogger'] = new \Psr\Log\NullLogger();
 378                         }
 379                         $p['profiler'] = isset( $p['profiler'] ) ? $p['profiler'] : null;
 380                         if ( !isset( $p['trxProfiler'] ) ) {
 381                                 $p['trxProfiler'] = new TransactionProfiler();
 382                         }
 383                         if ( !isset( $p['errorLogger'] ) ) {
 384                                 $p['errorLogger'] = function ( Exception $e ) {
 385                                         trigger_error( get_class( $e ) . ': ' . $e->getMessage(), E_WARNING );
 386                                 };
 387                         }
 388
 389                         $conn = new $class( $p );
 390                 } else {
 391                         $conn = null;
 392                 }
 393
 394                 return $conn;
 395         }
 396
 397         public function setLogger( LoggerInterface $logger ) {
 398                 $this->queryLogger = $logger;
 399         }
 400
 401         public function getServerInfo() {
 402                 return $this->getServerVersion();
 403         }
 404
 405         public function bufferResults( $buffer = null ) {
 406                 $res = !$this->getFlag( self::DBO_NOBUFFER );
 407                 if ( $buffer !== null ) {
 408                         $buffer
 409                                 ? $this->clearFlag( self::DBO_NOBUFFER )
 410                                 : $this->setFlag( self::DBO_NOBUFFER );
 411                 }
 412
 413                 return $res;
 414         }
 415
 416         /**
 417          * Turns on (false) or off (true) the automatic generation and sending
 418          * of a "we're sorry, but there has been a database error" page on
 419          * database errors. Default is on (false). When turned off, the
 420          * code should use lastErrno() and lastError() to handle the
 421          * situation as appropriate.
 422          *
 423          * Do not use this function outside of the Database classes.
 424          *
 425          * @param null|bool $ignoreErrors
 426          * @return bool The previous value of the flag.
 427          */
 428         protected function ignoreErrors( $ignoreErrors = null ) {
 429                 $res = $this->getFlag( self::DBO_IGNORE );
 430                 if ( $ignoreErrors !== null ) {
 431                         $ignoreErrors
 432                                 ? $this->setFlag( self::DBO_IGNORE )
 433                                 : $this->clearFlag( self::DBO_IGNORE );
 434                 }
 435
 436                 return $res;
 437         }
 438
 439         public function trxLevel() {
 440                 return $this->mTrxLevel;
 441         }
 442
 443         public function trxTimestamp() {
 444                 return $this->mTrxLevel ? $this->mTrxTimestamp : null;
 445         }
 446
 447         public function tablePrefix( $prefix = null ) {
 448                 $old = $this->mTablePrefix;
 449                 if ( $prefix !== null ) {
 450                         $this->mTablePrefix = $prefix;
 451                         $this->currentDomain = ( $this->mDBname != '' )
 452                                 ? new DatabaseDomain( $this->mDBname, null, $this->mTablePrefix )
 453                                 : DatabaseDomain::newUnspecified();
 454                 }
 455
 456                 return $old;
 457         }
 458
 459         public function dbSchema( $schema = null ) {
 460                 $old = $this->mSchema;
 461                 if ( $schema !== null ) {
 462                         $this->mSchema = $schema;
 463                 }
 464
 465                 return $old;
 466         }
 467
 468         public function getLBInfo( $name = null ) {
 469                 if ( is_null( $name ) ) {
 470                         return $this->mLBInfo;
 471                 } else {
 472                         if ( array_key_exists( $name, $this->mLBInfo ) ) {
 473                                 return $this->mLBInfo[$name];
 474                         } else {
 475                                 return null;
 476                         }
 477                 }
 478         }
 479
 480         public function setLBInfo( $name, $value = null ) {
 481                 if ( is_null( $value ) ) {
 482                         $this->mLBInfo = $name;
 483                 } else {
 484                         $this->mLBInfo[$name] = $value;
 485                 }
 486         }
 487
 488         public function setLazyMasterHandle( IDatabase $conn ) {
 489                 $this->lazyMasterHandle = $conn;
 490         }
 491
 492         /**
 493          * @return IDatabase|null
 494          * @see setLazyMasterHandle()
 495          * @since 1.27
 496          */
 497         protected function getLazyMasterHandle() {
 498                 return $this->lazyMasterHandle;
 499         }
 500
 501         public function implicitGroupby() {
 502                 return true;
 503         }
 504
 505         public function implicitOrderby() {
 506                 return true;
 507         }
 508
 509         public function lastQuery() {
 510                 return $this->mLastQuery;
 511         }
 512
 513         public function doneWrites() {
 514                 return (bool)$this->mDoneWrites;
 515         }
 516
 517         public function lastDoneWrites() {
 518                 return $this->mDoneWrites ?: false;
 519         }
 520
 521         public function writesPending() {
 522                 return $this->mTrxLevel && $this->mTrxDoneWrites;
 523         }
 524
 525         public function writesOrCallbacksPending() {
 526                 return $this->mTrxLevel && (
 527                         $this->mTrxDoneWrites || $this->mTrxIdleCallbacks || $this->mTrxPreCommitCallbacks
 528                 );
 529         }
 530
 531         public function pendingWriteQueryDuration( $type = self::ESTIMATE_TOTAL ) {
 532                 if ( !$this->mTrxLevel ) {
 533                         return false;
 534                 } elseif ( !$this->mTrxDoneWrites ) {
 535                         return 0.0;
 536                 }
 537
 538                 switch ( $type ) {
 539                         case self::ESTIMATE_DB_APPLY:
 540                                 $this->ping( $rtt );
 541                                 $rttAdjTotal = $this->mTrxWriteAdjQueryCount * $rtt;
 542                                 $applyTime = max( $this->mTrxWriteAdjDuration - $rttAdjTotal, 0 );
 543                                 // For omitted queries, make them count as something at least
 544                                 $omitted = $this->mTrxWriteQueryCount - $this->mTrxWriteAdjQueryCount;
 545                                 $applyTime += self::TINY_WRITE_SEC * $omitted;
 546
 547                                 return $applyTime;
 548                         default: // everything
 549                                 return $this->mTrxWriteDuration;
 550                 }
 551         }
 552
 553         public function pendingWriteCallers() {
 554                 return $this->mTrxLevel ? $this->mTrxWriteCallers : [];
 555         }
 556
 557         protected function pendingWriteAndCallbackCallers() {
 558                 if ( !$this->mTrxLevel ) {
 559                         return [];
 560                 }
 561
 562                 $fnames = $this->mTrxWriteCallers;
 563                 foreach ( [
 564                         $this->mTrxIdleCallbacks,
 565                         $this->mTrxPreCommitCallbacks,
 566                         $this->mTrxEndCallbacks
 567                 ] as $callbacks ) {
 568                         foreach ( $callbacks as $callback ) {
 569                                 $fnames[] = $callback[1];
 570                         }
 571                 }
 572
 573                 return $fnames;
 574         }
 575
 576         public function isOpen() {
 577                 return $this->mOpened;
 578         }
 579
 580         public function setFlag( $flag, $remember = self::REMEMBER_NOTHING ) {
 581                 if ( $remember === self::REMEMBER_PRIOR ) {
 582                         array_push( $this->priorFlags, $this->mFlags );
 583                 }
 584                 $this->mFlags |= $flag;
 585         }
 586
 587         public function clearFlag( $flag, $remember = self::REMEMBER_NOTHING ) {
 588                 if ( $remember === self::REMEMBER_PRIOR ) {
 589                         array_push( $this->priorFlags, $this->mFlags );
 590                 }
 591                 $this->mFlags &= ~$flag;
 592         }
 593
 594         public function restoreFlags( $state = self::RESTORE_PRIOR ) {
 595                 if ( !$this->priorFlags ) {
 596                         return;
 597                 }
 598
 599                 if ( $state === self::RESTORE_INITIAL ) {
 600                         $this->mFlags = reset( $this->priorFlags );
 601                         $this->priorFlags = [];
 602                 } else {
 603                         $this->mFlags = array_pop( $this->priorFlags );
 604                 }
 605         }
 606
 607         public function getFlag( $flag ) {
 608                 return !!( $this->mFlags & $flag );
 609         }
 610
 611         public function getProperty( $name ) {
 612                 return $this->$name;
 613         }
 614
 615         public function getDomainID() {
 616                 return $this->currentDomain->getId();
 617         }
 618
 619         final public function getWikiID() {
 620                 return $this->getDomainID();
 621         }
 622
 623         /**
 624          * Get information about an index into an object
 625          * @param string $table Table name
 626          * @param string $index Index name
 627          * @param string $fname Calling function name
 628          * @return mixed Database-specific index description class or false if the index does not exist
 629          */
 630         abstract function indexInfo( $table, $index, $fname = __METHOD__ );
 631
 632         /**
 633          * Wrapper for addslashes()
 634          *
 635          * @param string $s String to be slashed.
 636          * @return string Slashed string.
 637          */
 638         abstract function strencode( $s );
 639
 640         protected function installErrorHandler() {
 641                 $this->mPHPError = false;
 642                 $this->htmlErrors = ini_set( 'html_errors', '0' );
 643                 set_error_handler( [ $this, 'connectionErrorLogger' ] );
 644         }
 645
 646         /**
 647          * @return bool|string
 648          */
 649         protected function restoreErrorHandler() {
 650                 restore_error_handler();
 651                 if ( $this->htmlErrors !== false ) {
 652                         ini_set( 'html_errors', $this->htmlErrors );
 653                 }
 654                 if ( $this->mPHPError ) {
 655                         $error = preg_replace( '!\[<a.*</a>\]!', '', $this->mPHPError );
 656                         $error = preg_replace( '!^.*?:\s?(.*)$!', '$1', $error );
 657
 658                         return $error;
 659                 } else {
 660                         return false;
 661                 }
 662         }
 663
 664         /**
 665          * This method should not be used outside of Database classes
 666          *
 667          * @param int $errno
 668          * @param string $errstr
 669          */
 670         public function connectionErrorLogger( $errno, $errstr ) {
 671                 $this->mPHPError = $errstr;
 672         }
 673
 674         /**
 675          * Create a log context to pass to PSR-3 logger functions.
 676          *
 677          * @param array $extras Additional data to add to context
 678          * @return array
 679          */
 680         protected function getLogContext( array $extras = [] ) {
 681                 return array_merge(
 682                         [
 683                                 'db_server' => $this->mServer,
 684                                 'db_name' => $this->mDBname,
 685                                 'db_user' => $this->mUser,
 686                         ],
 687                         $extras
 688                 );
 689         }
 690
 691         public function close() {
 692                 if ( $this->mConn ) {
 693                         if ( $this->trxLevel() ) {
 694                                 $this->commit( __METHOD__, self::FLUSHING_INTERNAL );
 695                         }
 696
 697                         $closed = $this->closeConnection();
 698                         $this->mConn = false;
 699                 } elseif ( $this->mTrxIdleCallbacks || $this->mTrxEndCallbacks ) { // sanity
 700                         throw new RuntimeException( "Transaction callbacks still pending." );
 701                 } else {
 702                         $closed = true;
 703                 }
 704                 $this->mOpened = false;
 705
 706                 return $closed;
 707         }
 708
 709         /**
 710          * Make sure isOpen() returns true as a sanity check
 711          *
 712          * @throws DBUnexpectedError
 713          */
 714         protected function assertOpen() {
 715                 if ( !$this->isOpen() ) {
 716                         throw new DBUnexpectedError( $this, "DB connection was already closed." );
 717                 }
 718         }
 719
 720         /**
 721          * Closes underlying database connection
 722          * @since 1.20
 723          * @return bool Whether connection was closed successfully
 724          */
 725         abstract protected function closeConnection();
 726
 727         public function reportConnectionError( $error = 'Unknown error' ) {
 728                 $myError = $this->lastError();
 729                 if ( $myError ) {
 730                         $error = $myError;
 731                 }
 732
 733                 # New method
 734                 throw new DBConnectionError( $this, $error );
 735         }
 736
 737         /**
 738          * The DBMS-dependent part of query()
 739          *
 740          * @param string $sql SQL query.
 741          * @return ResultWrapper|bool Result object to feed to fetchObject,
 742          *   fetchRow, ...; or false on failure
 743          */
 744         abstract protected function doQuery( $sql );
 745
 746         /**
 747          * Determine whether a query writes to the DB.
 748          * Should return true if unsure.
 749          *
 750          * @param string $sql
 751          * @return bool
 752          */
 753         protected function isWriteQuery( $sql ) {
 754                 return !preg_match(
 755                         '/^(?:SELECT|BEGIN|ROLLBACK|COMMIT|SET|SHOW|EXPLAIN|\(SELECT)\b/i', $sql );
 756         }
 757
 758         /**
 759          * @param $sql
 760          * @return string|null
 761          */
 762         protected function getQueryVerb( $sql ) {
 763                 return preg_match( '/^\s*([a-z]+)/i', $sql, $m ) ? strtoupper( $m[1] ) : null;
 764         }
 765
 766         /**
 767          * Determine whether a SQL statement is sensitive to isolation level.
 768          * A SQL statement is considered transactable if its result could vary
 769          * depending on the transaction isolation level. Operational commands
 770          * such as 'SET' and 'SHOW' are not considered to be transactable.
 771          *
 772          * @param string $sql
 773          * @return bool
 774          */
 775         protected function isTransactableQuery( $sql ) {
 776                 $verb = $this->getQueryVerb( $sql );
 777                 return !in_array( $verb, [ 'BEGIN', 'COMMIT', 'ROLLBACK', 'SHOW', 'SET' ], true );
 778         }
 779
 780         /**
 781          * @param string $sql A SQL query
 782          * @return bool Whether $sql is SQL for creating/dropping a new TEMPORARY table
 783          */
 784         protected function registerTempTableOperation( $sql ) {
 785                 if ( preg_match(
 786                         '/^CREATE\s+TEMPORARY\s+TABLE\s+(?:IF\s+NOT\s+EXISTS\s+)?[`"\']?(\w+)[`"\']?/i',
 787                         $sql,
 788                         $matches
 789                 ) ) {
 790                         $this->mSessionTempTables[$matches[1]] = 1;
 791
 792                         return true;
 793                 } elseif ( preg_match(
 794                         '/^DROP\s+(?:TEMPORARY\s+)?TABLE\s+(?:IF\s+EXISTS\s+)?[`"\']?(\w+)[`"\']?/i',
 795                         $sql,
 796                         $matches
 797                 ) ) {
 798                         unset( $this->mSessionTempTables[$matches[1]] );
 799
 800                         return true;
 801                 } elseif ( preg_match(
 802                         '/^(?:INSERT\s+(?:\w+\s+)?INTO|UPDATE|DELETE\s+FROM)\s+[`"\']?(\w+)[`"\']?/i',
 803                         $sql,
 804                         $matches
 805                 ) ) {
 806                         return isset( $this->mSessionTempTables[$matches[1]] );
 807                 }
 808
 809                 return false;
 810         }
 811
 812         public function query( $sql, $fname = __METHOD__, $tempIgnore = false ) {
 813                 $priorWritesPending = $this->writesOrCallbacksPending();
 814                 $this->mLastQuery = $sql;
 815
 816                 $isWrite = $this->isWriteQuery( $sql ) && !$this->registerTempTableOperation( $sql );
 817                 if ( $isWrite ) {
 818                         $reason = $this->getReadOnlyReason();
 819                         if ( $reason !== false ) {
 820                                 throw new DBReadOnlyError( $this, "Database is read-only: $reason" );
 821                         }
 822                         # Set a flag indicating that writes have been done
 823                         $this->mDoneWrites = microtime( true );
 824                 }
 825
 826                 // Add trace comment to the begin of the sql string, right after the operator.
 827                 // Or, for one-word queries (like "BEGIN" or COMMIT") add it to the end (bug 42598)
 828                 $commentedSql = preg_replace( '/\s|$/', " /* $fname {$this->agent} */ ", $sql, 1 );
 829
 830                 # Start implicit transactions that wrap the request if DBO_TRX is enabled
 831                 if ( !$this->mTrxLevel && $this->getFlag( self::DBO_TRX )
 832                         && $this->isTransactableQuery( $sql )
 833                 ) {
 834                         $this->begin( __METHOD__ . " ($fname)", self::TRANSACTION_INTERNAL );
 835                         $this->mTrxAutomatic = true;
 836                 }
 837
 838                 # Keep track of whether the transaction has write queries pending
 839                 if ( $this->mTrxLevel && !$this->mTrxDoneWrites && $isWrite ) {
 840                         $this->mTrxDoneWrites = true;
 841                         $this->trxProfiler->transactionWritingIn(
 842                                 $this->mServer, $this->mDBname, $this->mTrxShortId );
 843                 }
 844
 845                 if ( $this->getFlag( self::DBO_DEBUG ) ) {
 846                         $this->queryLogger->debug( "{$this->mDBname} {$commentedSql}" );
 847                 }
 848
 849                 # Avoid fatals if close() was called
 850                 $this->assertOpen();
 851
 852                 # Send the query to the server
 853                 $ret = $this->doProfiledQuery( $sql, $commentedSql, $isWrite, $fname );
 854
 855                 # Try reconnecting if the connection was lost
 856                 if ( false === $ret && $this->wasErrorReissuable() ) {
 857                         $recoverable = $this->canRecoverFromDisconnect( $sql, $priorWritesPending );
 858                         # Stash the last error values before anything might clear them
 859                         $lastError = $this->lastError();
 860                         $lastErrno = $this->lastErrno();
 861                         # Update state tracking to reflect transaction loss due to disconnection
 862                         $this->handleSessionLoss();
 863                         if ( $this->reconnect() ) {
 864                                 $msg = __METHOD__ . ": lost connection to {$this->getServer()}; reconnected";
 865                                 $this->connLogger->warning( $msg );
 866                                 $this->queryLogger->warning(
 867                                         "$msg:\n" . ( new RuntimeException() )->getTraceAsString() );
 868
 869                                 if ( !$recoverable ) {
 870                                         # Callers may catch the exception and continue to use the DB
 871                                         $this->reportQueryError( $lastError, $lastErrno, $sql, $fname );
 872                                 } else {
 873                                         # Should be safe to silently retry the query
 874                                         $ret = $this->doProfiledQuery( $sql, $commentedSql, $isWrite, $fname );
 875                                 }
 876                         } else {
 877                                 $msg = __METHOD__ . ": lost connection to {$this->getServer()} permanently";
 878                                 $this->connLogger->error( $msg );
 879                         }
 880                 }
 881
 882                 if ( false === $ret ) {
 883                         # Deadlocks cause the entire transaction to abort, not just the statement.
 884                         # http://dev.mysql.com/doc/refman/5.7/en/innodb-error-handling.html
 885                         # https://www.postgresql.org/docs/9.1/static/explicit-locking.html
 886                         if ( $this->wasDeadlock() ) {
 887                                 if ( $this->explicitTrxActive() || $priorWritesPending ) {
 888                                         $tempIgnore = false; // not recoverable
 889                                 }
 890                                 # Update state tracking to reflect transaction loss
 891                                 $this->handleSessionLoss();
 892                         }
 893
 894                         $this->reportQueryError(
 895                                 $this->lastError(), $this->lastErrno(), $sql, $fname, $tempIgnore );
 896                 }
 897
 898                 $res = $this->resultObject( $ret );
 899
 900                 return $res;
 901         }
 902
 903         private function doProfiledQuery( $sql, $commentedSql, $isWrite, $fname ) {
 904                 $isMaster = !is_null( $this->getLBInfo( 'master' ) );
 905                 # generalizeSQL() will probably cut down the query to reasonable
 906                 # logging size most of the time. The substr is really just a sanity check.
 907                 if ( $isMaster ) {
 908                         $queryProf = 'query-m: ' . substr( self::generalizeSQL( $sql ), 0, 255 );
 909                 } else {
 910                         $queryProf = 'query: ' . substr( self::generalizeSQL( $sql ), 0, 255 );
 911                 }
 912
 913                 # Include query transaction state
 914                 $queryProf .= $this->mTrxShortId ? " [TRX#{$this->mTrxShortId}]" : "";
 915
 916                 $startTime = microtime( true );
 917                 if ( $this->profiler ) {
 918                         call_user_func( [ $this->profiler, 'profileIn' ], $queryProf );
 919                 }
 920                 $ret = $this->doQuery( $commentedSql );
 921                 if ( $this->profiler ) {
 922                         call_user_func( [ $this->profiler, 'profileOut' ], $queryProf );
 923                 }
 924                 $queryRuntime = max( microtime( true ) - $startTime, 0.0 );
 925
 926                 unset( $queryProfSection ); // profile out (if set)
 927
 928                 if ( $ret !== false ) {
 929                         $this->lastPing = $startTime;
 930                         if ( $isWrite && $this->mTrxLevel ) {
 931                                 $this->updateTrxWriteQueryTime( $sql, $queryRuntime );
 932                                 $this->mTrxWriteCallers[] = $fname;
 933                         }
 934                 }
 935
 936                 if ( $sql === self::PING_QUERY ) {
 937                         $this->mRTTEstimate = $queryRuntime;
 938                 }
 939
 940                 $this->trxProfiler->recordQueryCompletion(
 941                         $queryProf, $startTime, $isWrite, $this->affectedRows()
 942                 );
 943                 $this->queryLogger->debug( $sql, [
 944                         'method' => $fname,
 945                         'master' => $isMaster,
 946                         'runtime' => $queryRuntime,
 947                 ] );
 948
 949                 return $ret;
 950         }
 951
 952         /**
 953          * Update the estimated run-time of a query, not counting large row lock times
 954          *
 955          * LoadBalancer can be set to rollback transactions that will create huge replication
 956          * lag. It bases this estimate off of pendingWriteQueryDuration(). Certain simple
 957          * queries, like inserting a row can take a long time due to row locking. This method
 958          * uses some simple heuristics to discount those cases.
 959          *
 960          * @param string $sql A SQL write query
 961          * @param float $runtime Total runtime, including RTT
 962          */
 963         private function updateTrxWriteQueryTime( $sql, $runtime ) {
 964                 // Whether this is indicative of replica DB runtime (except for RBR or ws_repl)
 965                 $indicativeOfReplicaRuntime = true;
 966                 if ( $runtime > self::SLOW_WRITE_SEC ) {
 967                         $verb = $this->getQueryVerb( $sql );
 968                         // insert(), upsert(), replace() are fast unless bulky in size or blocked on locks
 969                         if ( $verb === 'INSERT' ) {
 970                                 $indicativeOfReplicaRuntime = $this->affectedRows() > self::SMALL_WRITE_ROWS;
 971                         } elseif ( $verb === 'REPLACE' ) {
 972                                 $indicativeOfReplicaRuntime = $this->affectedRows() > self::SMALL_WRITE_ROWS / 2;
 973                         }
 974                 }
 975
 976                 $this->mTrxWriteDuration += $runtime;
 977                 $this->mTrxWriteQueryCount += 1;
 978                 if ( $indicativeOfReplicaRuntime ) {
 979                         $this->mTrxWriteAdjDuration += $runtime;
 980                         $this->mTrxWriteAdjQueryCount += 1;
 981                 }
 982         }
 983
 984         private function canRecoverFromDisconnect( $sql, $priorWritesPending ) {
 985                 # Transaction dropped; this can mean lost writes, or REPEATABLE-READ snapshots.
 986                 # Dropped connections also mean that named locks are automatically released.
 987                 # Only allow error suppression in autocommit mode or when the lost transaction
 988                 # didn't matter anyway (aside from DBO_TRX snapshot loss).
 989                 if ( $this->mNamedLocksHeld ) {
 990                         return false; // possible critical section violation
 991                 } elseif ( $sql === 'COMMIT' ) {
 992                         return !$priorWritesPending; // nothing written anyway? (T127428)
 993                 } elseif ( $sql === 'ROLLBACK' ) {
 994                         return true; // transaction lost...which is also what was requested :)
 995                 } elseif ( $this->explicitTrxActive() ) {
 996                         return false; // don't drop atomocity
 997                 } elseif ( $priorWritesPending ) {
 998                         return false; // prior writes lost from implicit transaction
 999                 }
1000
1001                 return true;
1002         }
1003
1004         private function handleSessionLoss() {
1005                 $this->mTrxLevel = 0;
1006                 $this->mTrxIdleCallbacks = []; // bug 65263
1007                 $this->mTrxPreCommitCallbacks = []; // bug 65263
1008                 $this->mSessionTempTables = [];
1009                 $this->mNamedLocksHeld = [];
1010                 try {
1011                         // Handle callbacks in mTrxEndCallbacks
1012                         $this->runOnTransactionIdleCallbacks( self::TRIGGER_ROLLBACK );
1013                         $this->runTransactionListenerCallbacks( self::TRIGGER_ROLLBACK );
1014                         return null;
1015                 } catch ( Exception $e ) {
1016                         // Already logged; move on...
1017                         return $e;
1018                 }
1019         }
1020
1021         public function reportQueryError( $error, $errno, $sql, $fname, $tempIgnore = false ) {
1022                 if ( $this->ignoreErrors() || $tempIgnore ) {
1023                         $this->queryLogger->debug( "SQL ERROR (ignored): $error\n" );
1024                 } else {
1025                         $sql1line = mb_substr( str_replace( "\n", "\\n", $sql ), 0, 5 * 1024 );
1026                         $this->queryLogger->error(
1027                                 "{fname}\t{db_server}\t{errno}\t{error}\t{sql1line}",
1028                                 $this->getLogContext( [
1029                                         'method' => __METHOD__,
1030                                         'errno' => $errno,
1031                                         'error' => $error,
1032                                         'sql1line' => $sql1line,
1033                                         'fname' => $fname,
1034                                 ] )
1035                         );
1036                         $this->queryLogger->debug( "SQL ERROR: " . $error . "\n" );
1037                         throw new DBQueryError( $this, $error, $errno, $sql, $fname );
1038                 }
1039         }
1040
1041         public function freeResult( $res ) {
1042         }
1043
1044         public function selectField(
1045                 $table, $var, $cond = '', $fname = __METHOD__, $options = []
1046         ) {
1047                 if ( $var === '*' ) { // sanity
1048                         throw new DBUnexpectedError( $this, "Cannot use a * field: got '$var'" );
1049                 }
1050
1051                 if ( !is_array( $options ) ) {
1052                         $options = [ $options ];
1053                 }
1054
1055                 $options['LIMIT'] = 1;
1056
1057                 $res = $this->select( $table, $var, $cond, $fname, $options );
1058                 if ( $res === false || !$this->numRows( $res ) ) {
1059                         return false;
1060                 }
1061
1062                 $row = $this->fetchRow( $res );
1063
1064                 if ( $row !== false ) {
1065                         return reset( $row );
1066                 } else {
1067                         return false;
1068                 }
1069         }
1070
1071         public function selectFieldValues(
1072                 $table, $var, $cond = '', $fname = __METHOD__, $options = [], $join_conds = []
1073         ) {
1074                 if ( $var === '*' ) { // sanity
1075                         throw new DBUnexpectedError( $this, "Cannot use a * field" );
1076                 } elseif ( !is_string( $var ) ) { // sanity
1077                         throw new DBUnexpectedError( $this, "Cannot use an array of fields" );
1078                 }
1079
1080                 if ( !is_array( $options ) ) {
1081                         $options = [ $options ];
1082                 }
1083
1084                 $res = $this->select( $table, $var, $cond, $fname, $options, $join_conds );
1085                 if ( $res === false ) {
1086                         return false;
1087                 }
1088
1089                 $values = [];
1090                 foreach ( $res as $row ) {
1091                         $values[] = $row->$var;
1092                 }
1093
1094                 return $values;
1095         }
1096
1097         /**
1098          * Returns an optional USE INDEX clause to go after the table, and a
1099          * string to go at the end of the query.
1100          *
1101          * @param array $options Associative array of options to be turned into
1102          *   an SQL query, valid keys are listed in the function.
1103          * @return array
1104          * @see Database::select()
1105          */
1106         protected function makeSelectOptions( $options ) {
1107                 $preLimitTail = $postLimitTail = '';
1108                 $startOpts = '';
1109
1110                 $noKeyOptions = [];
1111
1112                 foreach ( $options as $key => $option ) {
1113                         if ( is_numeric( $key ) ) {
1114                                 $noKeyOptions[$option] = true;
1115                         }
1116                 }
1117
1118                 $preLimitTail .= $this->makeGroupByWithHaving( $options );
1119
1120                 $preLimitTail .= $this->makeOrderBy( $options );
1121
1122                 // if (isset($options['LIMIT'])) {
1123                 //      $tailOpts .= $this->limitResult('', $options['LIMIT'],
1124                 //              isset($options['OFFSET']) ? $options['OFFSET']
1125                 //              : false);
1126                 // }
1127
1128                 if ( isset( $noKeyOptions['FOR UPDATE'] ) ) {
1129                         $postLimitTail .= ' FOR UPDATE';
1130                 }
1131
1132                 if ( isset( $noKeyOptions['LOCK IN SHARE MODE'] ) ) {
1133                         $postLimitTail .= ' LOCK IN SHARE MODE';
1134                 }
1135
1136                 if ( isset( $noKeyOptions['DISTINCT'] ) || isset( $noKeyOptions['DISTINCTROW'] ) ) {
1137                         $startOpts .= 'DISTINCT';
1138                 }
1139
1140                 # Various MySQL extensions
1141                 if ( isset( $noKeyOptions['STRAIGHT_JOIN'] ) ) {
1142                         $startOpts .= ' /*! STRAIGHT_JOIN */';
1143                 }
1144
1145                 if ( isset( $noKeyOptions['HIGH_PRIORITY'] ) ) {
1146                         $startOpts .= ' HIGH_PRIORITY';
1147                 }
1148
1149                 if ( isset( $noKeyOptions['SQL_BIG_RESULT'] ) ) {
1150                         $startOpts .= ' SQL_BIG_RESULT';
1151                 }
1152
1153                 if ( isset( $noKeyOptions['SQL_BUFFER_RESULT'] ) ) {
1154                         $startOpts .= ' SQL_BUFFER_RESULT';
1155                 }
1156
1157                 if ( isset( $noKeyOptions['SQL_SMALL_RESULT'] ) ) {
1158                         $startOpts .= ' SQL_SMALL_RESULT';
1159                 }
1160
1161                 if ( isset( $noKeyOptions['SQL_CALC_FOUND_ROWS'] ) ) {
1162                         $startOpts .= ' SQL_CALC_FOUND_ROWS';
1163                 }
1164
1165                 if ( isset( $noKeyOptions['SQL_CACHE'] ) ) {
1166                         $startOpts .= ' SQL_CACHE';
1167                 }
1168
1169                 if ( isset( $noKeyOptions['SQL_NO_CACHE'] ) ) {
1170                         $startOpts .= ' SQL_NO_CACHE';
1171                 }
1172
1173                 if ( isset( $options['USE INDEX'] ) && is_string( $options['USE INDEX'] ) ) {
1174                         $useIndex = $this->useIndexClause( $options['USE INDEX'] );
1175                 } else {
1176                         $useIndex = '';
1177                 }
1178                 if ( isset( $options['IGNORE INDEX'] ) && is_string( $options['IGNORE INDEX'] ) ) {
1179                         $ignoreIndex = $this->ignoreIndexClause( $options['IGNORE INDEX'] );
1180                 } else {
1181                         $ignoreIndex = '';
1182                 }
1183
1184                 return [ $startOpts, $useIndex, $preLimitTail, $postLimitTail, $ignoreIndex ];
1185         }
1186
1187         /**
1188          * Returns an optional GROUP BY with an optional HAVING
1189          *
1190          * @param array $options Associative array of options
1191          * @return string
1192          * @see Database::select()
1193          * @since 1.21
1194          */
1195         protected function makeGroupByWithHaving( $options ) {
1196                 $sql = '';
1197                 if ( isset( $options['GROUP BY'] ) ) {
1198                         $gb = is_array( $options['GROUP BY'] )
1199                                 ? implode( ',', $options['GROUP BY'] )
1200                                 : $options['GROUP BY'];
1201                         $sql .= ' GROUP BY ' . $gb;
1202                 }
1203                 if ( isset( $options['HAVING'] ) ) {
1204                         $having = is_array( $options['HAVING'] )
1205                                 ? $this->makeList( $options['HAVING'], self::LIST_AND )
1206                                 : $options['HAVING'];
1207                         $sql .= ' HAVING ' . $having;
1208                 }
1209
1210                 return $sql;
1211         }
1212
1213         /**
1214          * Returns an optional ORDER BY
1215          *
1216          * @param array $options Associative array of options
1217          * @return string
1218          * @see Database::select()
1219          * @since 1.21
1220          */
1221         protected function makeOrderBy( $options ) {
1222                 if ( isset( $options['ORDER BY'] ) ) {
1223                         $ob = is_array( $options['ORDER BY'] )
1224                                 ? implode( ',', $options['ORDER BY'] )
1225                                 : $options['ORDER BY'];
1226
1227                         return ' ORDER BY ' . $ob;
1228                 }
1229
1230                 return '';
1231         }
1232
1233         public function select( $table, $vars, $conds = '', $fname = __METHOD__,
1234                 $options = [], $join_conds = [] ) {
1235                 $sql = $this->selectSQLText( $table, $vars, $conds, $fname, $options, $join_conds );
1236
1237                 return $this->query( $sql, $fname );
1238         }
1239
1240         public function selectSQLText( $table, $vars, $conds = '', $fname = __METHOD__,
1241                 $options = [], $join_conds = []
1242         ) {
1243                 if ( is_array( $vars ) ) {
1244                         $vars = implode( ',', $this->fieldNamesWithAlias( $vars ) );
1245                 }
1246
1247                 $options = (array)$options;
1248                 $useIndexes = ( isset( $options['USE INDEX'] ) && is_array( $options['USE INDEX'] ) )
1249                         ? $options['USE INDEX']
1250                         : [];
1251                 $ignoreIndexes = (
1252                         isset( $options['IGNORE INDEX'] ) &&
1253                         is_array( $options['IGNORE INDEX'] )
1254                 )
1255                         ? $options['IGNORE INDEX']
1256                         : [];
1257
1258                 if ( is_array( $table ) ) {
1259                         $from = ' FROM ' .
1260                                 $this->tableNamesWithIndexClauseOrJOIN(
1261                                         $table, $useIndexes, $ignoreIndexes, $join_conds );
1262                 } elseif ( $table != '' ) {
1263                         if ( $table[0] == ' ' ) {
1264                                 $from = ' FROM ' . $table;
1265                         } else {
1266                                 $from = ' FROM ' .
1267                                         $this->tableNamesWithIndexClauseOrJOIN(
1268                                                 [ $table ], $useIndexes, $ignoreIndexes, [] );
1269                         }
1270                 } else {
1271                         $from = '';
1272                 }
1273
1274                 list( $startOpts, $useIndex, $preLimitTail, $postLimitTail, $ignoreIndex ) =
1275                         $this->makeSelectOptions( $options );
1276
1277                 if ( !empty( $conds ) ) {
1278                         if ( is_array( $conds ) ) {
1279                                 $conds = $this->makeList( $conds, self::LIST_AND );
1280                         }
1281                         $sql = "SELECT $startOpts $vars $from $useIndex $ignoreIndex " .
1282                                 "WHERE $conds $preLimitTail";
1283                 } else {
1284                         $sql = "SELECT $startOpts $vars $from $useIndex $ignoreIndex $preLimitTail";
1285                 }
1286
1287                 if ( isset( $options['LIMIT'] ) ) {
1288                         $sql = $this->limitResult( $sql, $options['LIMIT'],
1289                                 isset( $options['OFFSET'] ) ? $options['OFFSET'] : false );
1290                 }
1291                 $sql = "$sql $postLimitTail";
1292
1293                 if ( isset( $options['EXPLAIN'] ) ) {
1294                         $sql = 'EXPLAIN ' . $sql;
1295                 }
1296
1297                 return $sql;
1298         }
1299
1300         public function selectRow( $table, $vars, $conds, $fname = __METHOD__,
1301                 $options = [], $join_conds = []
1302         ) {
1303                 $options = (array)$options;
1304                 $options['LIMIT'] = 1;
1305                 $res = $this->select( $table, $vars, $conds, $fname, $options, $join_conds );
1306
1307                 if ( $res === false ) {
1308                         return false;
1309                 }
1310
1311                 if ( !$this->numRows( $res ) ) {
1312                         return false;
1313                 }
1314
1315                 $obj = $this->fetchObject( $res );
1316
1317                 return $obj;
1318         }
1319
1320         public function estimateRowCount(
1321                 $table, $vars = '*', $conds = '', $fname = __METHOD__, $options = []
1322         ) {
1323                 $rows = 0;
1324                 $res = $this->select( $table, [ 'rowcount' => 'COUNT(*)' ], $conds, $fname, $options );
1325
1326                 if ( $res ) {
1327                         $row = $this->fetchRow( $res );
1328                         $rows = ( isset( $row['rowcount'] ) ) ? (int)$row['rowcount'] : 0;
1329                 }
1330
1331                 return $rows;
1332         }
1333
1334         public function selectRowCount(
1335                 $tables, $vars = '*', $conds = '', $fname = __METHOD__, $options = [], $join_conds = []
1336         ) {
1337                 $rows = 0;
1338                 $sql = $this->selectSQLText( $tables, '1', $conds, $fname, $options, $join_conds );
1339                 $res = $this->query( "SELECT COUNT(*) AS rowcount FROM ($sql) tmp_count", $fname );
1340
1341                 if ( $res ) {
1342                         $row = $this->fetchRow( $res );
1343                         $rows = ( isset( $row['rowcount'] ) ) ? (int)$row['rowcount'] : 0;
1344                 }
1345
1346                 return $rows;
1347         }
1348
1349         /**
1350          * Removes most variables from an SQL query and replaces them with X or N for numbers.
1351          * It's only slightly flawed. Don't use for anything important.
1352          *
1353          * @param string $sql A SQL Query
1354          *
1355          * @return string
1356          */
1357         protected static function generalizeSQL( $sql ) {
1358                 # This does the same as the regexp below would do, but in such a way
1359                 # as to avoid crashing php on some large strings.
1360                 # $sql = preg_replace( "/'([^\\\\']|\\\\.)*'|\"([^\\\\\"]|\\\\.)*\"/", "'X'", $sql );
1361
1362                 $sql = str_replace( "\\\\", '', $sql );
1363                 $sql = str_replace( "\\'", '', $sql );
1364                 $sql = str_replace( "\\\"", '', $sql );
1365                 $sql = preg_replace( "/'.*'/s", "'X'", $sql );
1366                 $sql = preg_replace( '/".*"/s', "'X'", $sql );
1367
1368                 # All newlines, tabs, etc replaced by single space
1369                 $sql = preg_replace( '/\s+/', ' ', $sql );
1370
1371                 # All numbers => N,
1372                 # except the ones surrounded by characters, e.g. l10n
1373                 $sql = preg_replace( '/-?\d+(,-?\d+)+/s', 'N,...,N', $sql );
1374                 $sql = preg_replace( '/(?<![a-zA-Z])-?\d+(?![a-zA-Z])/s', 'N', $sql );
1375
1376                 return $sql;
1377         }
1378
1379         public function fieldExists( $table, $field, $fname = __METHOD__ ) {
1380                 $info = $this->fieldInfo( $table, $field );
1381
1382                 return (bool)$info;
1383         }
1384
1385         public function indexExists( $table, $index, $fname = __METHOD__ ) {
1386                 if ( !$this->tableExists( $table ) ) {
1387                         return null;
1388                 }
1389
1390                 $info = $this->indexInfo( $table, $index, $fname );
1391                 if ( is_null( $info ) ) {
1392                         return null;
1393                 } else {
1394                         return $info !== false;
1395                 }
1396         }
1397
1398         public function tableExists( $table, $fname = __METHOD__ ) {
1399                 $tableRaw = $this->tableName( $table, 'raw' );
1400                 if ( isset( $this->mSessionTempTables[$tableRaw] ) ) {
1401                         return true; // already known to exist
1402                 }
1403
1404                 $table = $this->tableName( $table );
1405                 $old = $this->ignoreErrors( true );
1406                 $res = $this->query( "SELECT 1 FROM $table LIMIT 1", $fname );
1407                 $this->ignoreErrors( $old );
1408
1409                 return (bool)$res;
1410         }
1411
1412         public function indexUnique( $table, $index ) {
1413                 $indexInfo = $this->indexInfo( $table, $index );
1414
1415                 if ( !$indexInfo ) {
1416                         return null;
1417                 }
1418
1419                 return !$indexInfo[0]->Non_unique;
1420         }
1421
1422         /**
1423          * Helper for Database::insert().
1424          *
1425          * @param array $options
1426          * @return string
1427          */
1428         protected function makeInsertOptions( $options ) {
1429                 return implode( ' ', $options );
1430         }
1431
1432         public function insert( $table, $a, $fname = __METHOD__, $options = [] ) {
1433                 # No rows to insert, easy just return now
1434                 if ( !count( $a ) ) {
1435                         return true;
1436                 }
1437
1438                 $table = $this->tableName( $table );
1439
1440                 if ( !is_array( $options ) ) {
1441                         $options = [ $options ];
1442                 }
1443
1444                 $fh = null;
1445                 if ( isset( $options['fileHandle'] ) ) {
1446                         $fh = $options['fileHandle'];
1447                 }
1448                 $options = $this->makeInsertOptions( $options );
1449
1450                 if ( isset( $a[0] ) && is_array( $a[0] ) ) {
1451                         $multi = true;
1452                         $keys = array_keys( $a[0] );
1453                 } else {
1454                         $multi = false;
1455                         $keys = array_keys( $a );
1456                 }
1457
1458                 $sql = 'INSERT ' . $options .
1459                         " INTO $table (" . implode( ',', $keys ) . ') VALUES ';
1460
1461                 if ( $multi ) {
1462                         $first = true;
1463                         foreach ( $a as $row ) {
1464                                 if ( $first ) {
1465                                         $first = false;
1466                                 } else {
1467                                         $sql .= ',';
1468                                 }
1469                                 $sql .= '(' . $this->makeList( $row ) . ')';
1470                         }
1471                 } else {
1472                         $sql .= '(' . $this->makeList( $a ) . ')';
1473                 }
1474
1475                 if ( $fh !== null && false === fwrite( $fh, $sql ) ) {
1476                         return false;
1477                 } elseif ( $fh !== null ) {
1478                         return true;
1479                 }
1480
1481                 return (bool)$this->query( $sql, $fname );
1482         }
1483
1484         /**
1485          * Make UPDATE options array for Database::makeUpdateOptions
1486          *
1487          * @param array $options
1488          * @return array
1489          */
1490         protected function makeUpdateOptionsArray( $options ) {
1491                 if ( !is_array( $options ) ) {
1492                         $options = [ $options ];
1493                 }
1494
1495                 $opts = [];
1496
1497                 if ( in_array( 'IGNORE', $options ) ) {
1498                         $opts[] = 'IGNORE';
1499                 }
1500
1501                 return $opts;
1502         }
1503
1504         /**
1505          * Make UPDATE options for the Database::update function
1506          *
1507          * @param array $options The options passed to Database::update
1508          * @return string
1509          */
1510         protected function makeUpdateOptions( $options ) {
1511                 $opts = $this->makeUpdateOptionsArray( $options );
1512
1513                 return implode( ' ', $opts );
1514         }
1515
1516         public function update( $table, $values, $conds, $fname = __METHOD__, $options = [] ) {
1517                 $table = $this->tableName( $table );
1518                 $opts = $this->makeUpdateOptions( $options );
1519                 $sql = "UPDATE $opts $table SET " . $this->makeList( $values, self::LIST_SET );
1520
1521                 if ( $conds !== [] && $conds !== '*' ) {
1522                         $sql .= " WHERE " . $this->makeList( $conds, self::LIST_AND );
1523                 }
1524
1525                 return $this->query( $sql, $fname );
1526         }
1527
1528         public function makeList( $a, $mode = self::LIST_COMMA ) {
1529                 if ( !is_array( $a ) ) {
1530                         throw new DBUnexpectedError( $this, __METHOD__ . ' called with incorrect parameters' );
1531                 }
1532
1533                 $first = true;
1534                 $list = '';
1535
1536                 foreach ( $a as $field => $value ) {
1537                         if ( !$first ) {
1538                                 if ( $mode == self::LIST_AND ) {
1539                                         $list .= ' AND ';
1540                                 } elseif ( $mode == self::LIST_OR ) {
1541                                         $list .= ' OR ';
1542                                 } else {
1543                                         $list .= ',';
1544                                 }
1545                         } else {
1546                                 $first = false;
1547                         }
1548
1549                         if ( ( $mode == self::LIST_AND || $mode == self::LIST_OR ) && is_numeric( $field ) ) {
1550                                 $list .= "($value)";
1551                         } elseif ( $mode == self::LIST_SET && is_numeric( $field ) ) {
1552                                 $list .= "$value";
1553                         } elseif (
1554                                 ( $mode == self::LIST_AND || $mode == self::LIST_OR ) && is_array( $value )
1555                         ) {
1556                                 // Remove null from array to be handled separately if found
1557                                 $includeNull = false;
1558                                 foreach ( array_keys( $value, null, true ) as $nullKey ) {
1559                                         $includeNull = true;
1560                                         unset( $value[$nullKey] );
1561                                 }
1562                                 if ( count( $value ) == 0 && !$includeNull ) {
1563                                         throw new InvalidArgumentException(
1564                                                 __METHOD__ . ": empty input for field $field" );
1565                                 } elseif ( count( $value ) == 0 ) {
1566                                         // only check if $field is null
1567                                         $list .= "$field IS NULL";
1568                                 } else {
1569                                         // IN clause contains at least one valid element
1570                                         if ( $includeNull ) {
1571                                                 // Group subconditions to ensure correct precedence
1572                                                 $list .= '(';
1573                                         }
1574                                         if ( count( $value ) == 1 ) {
1575                                                 // Special-case single values, as IN isn't terribly efficient
1576                                                 // Don't necessarily assume the single key is 0; we don't
1577                                                 // enforce linear numeric ordering on other arrays here.
1578                                                 $value = array_values( $value )[0];
1579                                                 $list .= $field . " = " . $this->addQuotes( $value );
1580                                         } else {
1581                                                 $list .= $field . " IN (" . $this->makeList( $value ) . ") ";
1582                                         }
1583                                         // if null present in array, append IS NULL
1584                                         if ( $includeNull ) {
1585                                                 $list .= " OR $field IS NULL)";
1586                                         }
1587                                 }
1588                         } elseif ( $value === null ) {
1589                                 if ( $mode == self::LIST_AND || $mode == self::LIST_OR ) {
1590                                         $list .= "$field IS ";
1591                                 } elseif ( $mode == self::LIST_SET ) {
1592                                         $list .= "$field = ";
1593                                 }
1594                                 $list .= 'NULL';
1595                         } else {
1596                                 if (
1597                                         $mode == self::LIST_AND || $mode == self::LIST_OR || $mode == self::LIST_SET
1598                                 ) {
1599                                         $list .= "$field = ";
1600                                 }
1601                                 $list .= $mode == self::LIST_NAMES ? $value : $this->addQuotes( $value );
1602                         }
1603                 }
1604
1605                 return $list;
1606         }
1607
1608         public function makeWhereFrom2d( $data, $baseKey, $subKey ) {
1609                 $conds = [];
1610
1611                 foreach ( $data as $base => $sub ) {
1612                         if ( count( $sub ) ) {
1613                                 $conds[] = $this->makeList(
1614                                         [ $baseKey => $base, $subKey => array_keys( $sub ) ],
1615                                         self::LIST_AND );
1616                         }
1617                 }
1618
1619                 if ( $conds ) {
1620                         return $this->makeList( $conds, self::LIST_OR );
1621                 } else {
1622                         // Nothing to search for...
1623                         return false;
1624                 }
1625         }
1626
1627         public function aggregateValue( $valuedata, $valuename = 'value' ) {
1628                 return $valuename;
1629         }
1630
1631         public function bitNot( $field ) {
1632                 return "(~$field)";
1633         }
1634
1635         public function bitAnd( $fieldLeft, $fieldRight ) {
1636                 return "($fieldLeft & $fieldRight)";
1637         }
1638
1639         public function bitOr( $fieldLeft, $fieldRight ) {
1640                 return "($fieldLeft | $fieldRight)";
1641         }
1642
1643         public function buildConcat( $stringList ) {
1644                 return 'CONCAT(' . implode( ',', $stringList ) . ')';
1645         }
1646
1647         public function buildGroupConcatField(
1648                 $delim, $table, $field, $conds = '', $join_conds = []
1649         ) {
1650                 $fld = "GROUP_CONCAT($field SEPARATOR " . $this->addQuotes( $delim ) . ')';
1651
1652                 return '(' . $this->selectSQLText( $table, $fld, $conds, null, [], $join_conds ) . ')';
1653         }
1654
1655         public function buildStringCast( $field ) {
1656                 return $field;
1657         }
1658
1659         public function selectDB( $db ) {
1660                 # Stub. Shouldn't cause serious problems if it's not overridden, but
1661                 # if your database engine supports a concept similar to MySQL's
1662                 # databases you may as well.
1663                 $this->mDBname = $db;
1664
1665                 return true;
1666         }
1667
1668         public function getDBname() {
1669                 return $this->mDBname;
1670         }
1671
1672         public function getServer() {
1673                 return $this->mServer;
1674         }
1675
1676         public function tableName( $name, $format = 'quoted' ) {
1677                 # Skip the entire process when we have a string quoted on both ends.
1678                 # Note that we check the end so that we will still quote any use of
1679                 # use of `database`.table. But won't break things if someone wants
1680                 # to query a database table with a dot in the name.
1681                 if ( $this->isQuotedIdentifier( $name ) ) {
1682                         return $name;
1683                 }
1684
1685                 # Lets test for any bits of text that should never show up in a table
1686                 # name. Basically anything like JOIN or ON which are actually part of
1687                 # SQL queries, but may end up inside of the table value to combine
1688                 # sql. Such as how the API is doing.
1689                 # Note that we use a whitespace test rather than a \b test to avoid
1690                 # any remote case where a word like on may be inside of a table name
1691                 # surrounded by symbols which may be considered word breaks.
1692                 if ( preg_match( '/(^|\s)(DISTINCT|JOIN|ON|AS)(\s|$)/i', $name ) !== 0 ) {
1693                         return $name;
1694                 }
1695
1696                 # Split database and table into proper variables.
1697                 # We reverse the explode so that database.table and table both output
1698                 # the correct table.
1699                 $dbDetails = explode( '.', $name, 3 );
1700                 if ( count( $dbDetails ) == 3 ) {
1701                         list( $database, $schema, $table ) = $dbDetails;
1702                         # We don't want any prefix added in this case
1703                         $prefix = '';
1704                 } elseif ( count( $dbDetails ) == 2 ) {
1705                         list( $database, $table ) = $dbDetails;
1706                         # We don't want any prefix added in this case
1707                         # In dbs that support it, $database may actually be the schema
1708                         # but that doesn't affect any of the functionality here
1709                         $prefix = '';
1710                         $schema = '';
1711                 } else {
1712                         list( $table ) = $dbDetails;
1713                         if ( isset( $this->tableAliases[$table] ) ) {
1714                                 $database = $this->tableAliases[$table]['dbname'];
1715                                 $schema = is_string( $this->tableAliases[$table]['schema'] )
1716                                         ? $this->tableAliases[$table]['schema']
1717                                         : $this->mSchema;
1718                                 $prefix = is_string( $this->tableAliases[$table]['prefix'] )
1719                                         ? $this->tableAliases[$table]['prefix']
1720                                         : $this->mTablePrefix;
1721                         } else {
1722                                 $database = '';
1723                                 $schema = $this->mSchema; # Default schema
1724                                 $prefix = $this->mTablePrefix; # Default prefix
1725                         }
1726                 }
1727
1728                 # Quote $table and apply the prefix if not quoted.
1729                 # $tableName might be empty if this is called from Database::replaceVars()
1730                 $tableName = "{$prefix}{$table}";
1731                 if ( $format == 'quoted'
1732                         && !$this->isQuotedIdentifier( $tableName ) && $tableName !== ''
1733                 ) {
1734                         $tableName = $this->addIdentifierQuotes( $tableName );
1735                 }
1736
1737                 # Quote $schema and merge it with the table name if needed
1738                 if ( strlen( $schema ) ) {
1739                         if ( $format == 'quoted' && !$this->isQuotedIdentifier( $schema ) ) {
1740                                 $schema = $this->addIdentifierQuotes( $schema );
1741                         }
1742                         $tableName = $schema . '.' . $tableName;
1743                 }
1744
1745                 # Quote $database and merge it with the table name if needed
1746                 if ( $database !== '' ) {
1747                         if ( $format == 'quoted' && !$this->isQuotedIdentifier( $database ) ) {
1748                                 $database = $this->addIdentifierQuotes( $database );
1749                         }
1750                         $tableName = $database . '.' . $tableName;
1751                 }
1752
1753                 return $tableName;
1754         }
1755
1756         public function tableNames() {
1757                 $inArray = func_get_args();
1758                 $retVal = [];
1759
1760                 foreach ( $inArray as $name ) {
1761                         $retVal[$name] = $this->tableName( $name );
1762                 }
1763
1764                 return $retVal;
1765         }
1766
1767         public function tableNamesN() {
1768                 $inArray = func_get_args();
1769                 $retVal = [];
1770
1771                 foreach ( $inArray as $name ) {
1772                         $retVal[] = $this->tableName( $name );
1773                 }
1774
1775                 return $retVal;
1776         }
1777
1778         /**
1779          * Get an aliased table name
1780          * e.g. tableName AS newTableName
1781          *
1782          * @param string $name Table name, see tableName()
1783          * @param string|bool $alias Alias (optional)
1784          * @return string SQL name for aliased table. Will not alias a table to its own name
1785          */
1786         protected function tableNameWithAlias( $name, $alias = false ) {
1787                 if ( !$alias || $alias == $name ) {
1788                         return $this->tableName( $name );
1789                 } else {
1790                         return $this->tableName( $name ) . ' ' . $this->addIdentifierQuotes( $alias );
1791                 }
1792         }
1793
1794         /**
1795          * Gets an array of aliased table names
1796          *
1797          * @param array $tables [ [alias] => table ]
1798          * @return string[] See tableNameWithAlias()
1799          */
1800         protected function tableNamesWithAlias( $tables ) {
1801                 $retval = [];
1802                 foreach ( $tables as $alias => $table ) {
1803                         if ( is_numeric( $alias ) ) {
1804                                 $alias = $table;
1805                         }
1806                         $retval[] = $this->tableNameWithAlias( $table, $alias );
1807                 }
1808
1809                 return $retval;
1810         }
1811
1812         /**
1813          * Get an aliased field name
1814          * e.g. fieldName AS newFieldName
1815          *
1816          * @param string $name Field name
1817          * @param string|bool $alias Alias (optional)
1818          * @return string SQL name for aliased field. Will not alias a field to its own name
1819          */
1820         protected function fieldNameWithAlias( $name, $alias = false ) {
1821                 if ( !$alias || (string)$alias === (string)$name ) {
1822                         return $name;
1823                 } else {
1824                         return $name . ' AS ' . $this->addIdentifierQuotes( $alias ); // PostgreSQL needs AS
1825                 }
1826         }
1827
1828         /**
1829          * Gets an array of aliased field names
1830          *
1831          * @param array $fields [ [alias] => field ]
1832          * @return string[] See fieldNameWithAlias()
1833          */
1834         protected function fieldNamesWithAlias( $fields ) {
1835                 $retval = [];
1836                 foreach ( $fields as $alias => $field ) {
1837                         if ( is_numeric( $alias ) ) {
1838                                 $alias = $field;
1839                         }
1840                         $retval[] = $this->fieldNameWithAlias( $field, $alias );
1841                 }
1842
1843                 return $retval;
1844         }
1845
1846         /**
1847          * Get the aliased table name clause for a FROM clause
1848          * which might have a JOIN and/or USE INDEX or IGNORE INDEX clause
1849          *
1850          * @param array $tables ( [alias] => table )
1851          * @param array $use_index Same as for select()
1852          * @param array $ignore_index Same as for select()
1853          * @param array $join_conds Same as for select()
1854          * @return string
1855          */
1856         protected function tableNamesWithIndexClauseOrJOIN(
1857                 $tables, $use_index = [], $ignore_index = [], $join_conds = []
1858         ) {
1859                 $ret = [];
1860                 $retJOIN = [];
1861                 $use_index = (array)$use_index;
1862                 $ignore_index = (array)$ignore_index;
1863                 $join_conds = (array)$join_conds;
1864
1865                 foreach ( $tables as $alias => $table ) {
1866                         if ( !is_string( $alias ) ) {
1867                                 // No alias? Set it equal to the table name
1868                                 $alias = $table;
1869                         }
1870                         // Is there a JOIN clause for this table?
1871                         if ( isset( $join_conds[$alias] ) ) {
1872                                 list( $joinType, $conds ) = $join_conds[$alias];
1873                                 $tableClause = $joinType;
1874                                 $tableClause .= ' ' . $this->tableNameWithAlias( $table, $alias );
1875                                 if ( isset( $use_index[$alias] ) ) { // has USE INDEX?
1876                                         $use = $this->useIndexClause( implode( ',', (array)$use_index[$alias] ) );
1877                                         if ( $use != '' ) {
1878                                                 $tableClause .= ' ' . $use;
1879                                         }
1880                                 }
1881                                 if ( isset( $ignore_index[$alias] ) ) { // has IGNORE INDEX?
1882                                         $ignore = $this->ignoreIndexClause(
1883                                                 implode( ',', (array)$ignore_index[$alias] ) );
1884                                         if ( $ignore != '' ) {
1885                                                 $tableClause .= ' ' . $ignore;
1886                                         }
1887                                 }
1888                                 $on = $this->makeList( (array)$conds, self::LIST_AND );
1889                                 if ( $on != '' ) {
1890                                         $tableClause .= ' ON (' . $on . ')';
1891                                 }
1892
1893                                 $retJOIN[] = $tableClause;
1894                         } elseif ( isset( $use_index[$alias] ) ) {
1895                                 // Is there an INDEX clause for this table?
1896                                 $tableClause = $this->tableNameWithAlias( $table, $alias );
1897                                 $tableClause .= ' ' . $this->useIndexClause(
1898                                                 implode( ',', (array)$use_index[$alias] )
1899                                         );
1900
1901                                 $ret[] = $tableClause;
1902                         } elseif ( isset( $ignore_index[$alias] ) ) {
1903                                 // Is there an INDEX clause for this table?
1904                                 $tableClause = $this->tableNameWithAlias( $table, $alias );
1905                                 $tableClause .= ' ' . $this->ignoreIndexClause(
1906                                                 implode( ',', (array)$ignore_index[$alias] )
1907                                         );
1908
1909                                 $ret[] = $tableClause;
1910                         } else {
1911                                 $tableClause = $this->tableNameWithAlias( $table, $alias );
1912
1913                                 $ret[] = $tableClause;
1914                         }
1915                 }
1916
1917                 // We can't separate explicit JOIN clauses with ',', use ' ' for those
1918                 $implicitJoins = !empty( $ret ) ? implode( ',', $ret ) : "";
1919                 $explicitJoins = !empty( $retJOIN ) ? implode( ' ', $retJOIN ) : "";
1920
1921                 // Compile our final table clause
1922                 return implode( ' ', [ $implicitJoins, $explicitJoins ] );
1923         }
1924
1925         /**
1926          * Get the name of an index in a given table.
1927          *
1928          * @param string $index
1929          * @return string
1930          */
1931         protected function indexName( $index ) {
1932                 return $index;
1933         }
1934
1935         public function addQuotes( $s ) {
1936                 if ( $s instanceof Blob ) {
1937                         $s = $s->fetch();
1938                 }
1939                 if ( $s === null ) {
1940                         return 'NULL';
1941                 } elseif ( is_bool( $s ) ) {
1942                         return (int)$s;
1943                 } else {
1944                         # This will also quote numeric values. This should be harmless,
1945                         # and protects against weird problems that occur when they really
1946                         # _are_ strings such as article titles and string->number->string
1947                         # conversion is not 1:1.
1948                         return "'" . $this->strencode( $s ) . "'";
1949                 }
1950         }
1951
1952         /**
1953          * Quotes an identifier using `backticks` or "double quotes" depending on the database type.
1954          * MySQL uses `backticks` while basically everything else uses double quotes.
1955          * Since MySQL is the odd one out here the double quotes are our generic
1956          * and we implement backticks in DatabaseMysql.
1957          *
1958          * @param string $s
1959          * @return string
1960          */
1961         public function addIdentifierQuotes( $s ) {
1962                 return '"' . str_replace( '"', '""', $s ) . '"';
1963         }
1964
1965         /**
1966          * Returns if the given identifier looks quoted or not according to
1967          * the database convention for quoting identifiers .
1968          *
1969          * @note Do not use this to determine if untrusted input is safe.
1970          *   A malicious user can trick this function.
1971          * @param string $name
1972          * @return bool
1973          */
1974         public function isQuotedIdentifier( $name ) {
1975                 return $name[0] == '"' && substr( $name, -1, 1 ) == '"';
1976         }
1977
1978         /**
1979          * @param string $s
1980          * @return string
1981          */
1982         protected function escapeLikeInternal( $s ) {
1983                 return addcslashes( $s, '\%_' );
1984         }
1985
1986         public function buildLike() {
1987                 $params = func_get_args();
1988
1989                 if ( count( $params ) > 0 && is_array( $params[0] ) ) {
1990                         $params = $params[0];
1991                 }
1992
1993                 $s = '';
1994
1995                 foreach ( $params as $value ) {
1996                         if ( $value instanceof LikeMatch ) {
1997                                 $s .= $value->toString();
1998                         } else {
1999                                 $s .= $this->escapeLikeInternal( $value );
2000                         }
2001                 }
2002
2003                 return " LIKE {$this->addQuotes( $s )} ";
2004         }
2005
2006         public function anyChar() {
2007                 return new LikeMatch( '_' );
2008         }
2009
2010         public function anyString() {
2011                 return new LikeMatch( '%' );
2012         }
2013
2014         public function nextSequenceValue( $seqName ) {
2015                 return null;
2016         }
2017
2018         /**
2019          * USE INDEX clause. Unlikely to be useful for anything but MySQL. This
2020          * is only needed because a) MySQL must be as efficient as possible due to
2021          * its use on Wikipedia, and b) MySQL 4.0 is kind of dumb sometimes about
2022          * which index to pick. Anyway, other databases might have different
2023          * indexes on a given table. So don't bother overriding this unless you're
2024          * MySQL.
2025          * @param string $index
2026          * @return string
2027          */
2028         public function useIndexClause( $index ) {
2029                 return '';
2030         }
2031
2032         /**
2033          * IGNORE INDEX clause. Unlikely to be useful for anything but MySQL. This
2034          * is only needed because a) MySQL must be as efficient as possible due to
2035          * its use on Wikipedia, and b) MySQL 4.0 is kind of dumb sometimes about
2036          * which index to pick. Anyway, other databases might have different
2037          * indexes on a given table. So don't bother overriding this unless you're
2038          * MySQL.
2039          * @param string $index
2040          * @return string
2041          */
2042         public function ignoreIndexClause( $index ) {
2043                 return '';
2044         }
2045
2046         public function replace( $table, $uniqueIndexes, $rows, $fname = __METHOD__ ) {
2047                 $quotedTable = $this->tableName( $table );
2048
2049                 if ( count( $rows ) == 0 ) {
2050                         return;
2051                 }
2052
2053                 # Single row case
2054                 if ( !is_array( reset( $rows ) ) ) {
2055                         $rows = [ $rows ];
2056                 }
2057
2058                 // @FXIME: this is not atomic, but a trx would break affectedRows()
2059                 foreach ( $rows as $row ) {
2060                         # Delete rows which collide
2061                         if ( $uniqueIndexes ) {
2062                                 $sql = "DELETE FROM $quotedTable WHERE ";
2063                                 $first = true;
2064                                 foreach ( $uniqueIndexes as $index ) {
2065                                         if ( $first ) {
2066                                                 $first = false;
2067                                                 $sql .= '( ';
2068                                         } else {
2069                                                 $sql .= ' ) OR ( ';
2070                                         }
2071                                         if ( is_array( $index ) ) {
2072                                                 $first2 = true;
2073                                                 foreach ( $index as $col ) {
2074                                                         if ( $first2 ) {
2075                                                                 $first2 = false;
2076                                                         } else {
2077                                                                 $sql .= ' AND ';
2078                                                         }
2079                                                         $sql .= $col . '=' . $this->addQuotes( $row[$col] );
2080                                                 }
2081                                         } else {
2082                                                 $sql .= $index . '=' . $this->addQuotes( $row[$index] );
2083                                         }
2084                                 }
2085                                 $sql .= ' )';
2086                                 $this->query( $sql, $fname );
2087                         }
2088
2089                         # Now insert the row
2090                         $this->insert( $table, $row, $fname );
2091                 }
2092         }
2093
2094         /**
2095          * REPLACE query wrapper for MySQL and SQLite, which have a native REPLACE
2096          * statement.
2097          *
2098          * @param string $table Table name
2099          * @param array|string $rows Row(s) to insert
2100          * @param string $fname Caller function name
2101          *
2102          * @return ResultWrapper
2103          */
2104         protected function nativeReplace( $table, $rows, $fname ) {
2105                 $table = $this->tableName( $table );
2106
2107                 # Single row case
2108                 if ( !is_array( reset( $rows ) ) ) {
2109                         $rows = [ $rows ];
2110                 }
2111
2112                 $sql = "REPLACE INTO $table (" . implode( ',', array_keys( $rows[0] ) ) . ') VALUES ';
2113                 $first = true;
2114
2115                 foreach ( $rows as $row ) {
2116                         if ( $first ) {
2117                                 $first = false;
2118                         } else {
2119                                 $sql .= ',';
2120                         }
2121
2122                         $sql .= '(' . $this->makeList( $row ) . ')';
2123                 }
2124
2125                 return $this->query( $sql, $fname );
2126         }
2127
2128         public function upsert( $table, array $rows, array $uniqueIndexes, array $set,
2129                 $fname = __METHOD__
2130         ) {
2131                 if ( !count( $rows ) ) {
2132                         return true; // nothing to do
2133                 }
2134
2135                 if ( !is_array( reset( $rows ) ) ) {
2136                         $rows = [ $rows ];
2137                 }
2138
2139                 if ( count( $uniqueIndexes ) ) {
2140                         $clauses = []; // list WHERE clauses that each identify a single row
2141                         foreach ( $rows as $row ) {
2142                                 foreach ( $uniqueIndexes as $index ) {
2143                                         $index = is_array( $index ) ? $index : [ $index ]; // columns
2144                                         $rowKey = []; // unique key to this row
2145                                         foreach ( $index as $column ) {
2146                                                 $rowKey[$column] = $row[$column];
2147                                         }
2148                                         $clauses[] = $this->makeList( $rowKey, self::LIST_AND );
2149                                 }
2150                         }
2151                         $where = [ $this->makeList( $clauses, self::LIST_OR ) ];
2152                 } else {
2153                         $where = false;
2154                 }
2155
2156                 $useTrx = !$this->mTrxLevel;
2157                 if ( $useTrx ) {
2158                         $this->begin( $fname, self::TRANSACTION_INTERNAL );
2159                 }
2160                 try {
2161                         # Update any existing conflicting row(s)
2162                         if ( $where !== false ) {
2163                                 $ok = $this->update( $table, $set, $where, $fname );
2164                         } else {
2165                                 $ok = true;
2166                         }
2167                         # Now insert any non-conflicting row(s)
2168                         $ok = $this->insert( $table, $rows, $fname, [ 'IGNORE' ] ) && $ok;
2169                 } catch ( Exception $e ) {
2170                         if ( $useTrx ) {
2171                                 $this->rollback( $fname, self::FLUSHING_INTERNAL );
2172                         }
2173                         throw $e;
2174                 }
2175                 if ( $useTrx ) {
2176                         $this->commit( $fname, self::FLUSHING_INTERNAL );
2177                 }
2178
2179                 return $ok;
2180         }
2181
2182         public function deleteJoin( $delTable, $joinTable, $delVar, $joinVar, $conds,
2183                 $fname = __METHOD__
2184         ) {
2185                 if ( !$conds ) {
2186                         throw new DBUnexpectedError( $this, __METHOD__ . ' called with empty $conds' );
2187                 }
2188
2189                 $delTable = $this->tableName( $delTable );
2190                 $joinTable = $this->tableName( $joinTable );
2191                 $sql = "DELETE FROM $delTable WHERE $delVar IN (SELECT $joinVar FROM $joinTable ";
2192                 if ( $conds != '*' ) {
2193                         $sql .= 'WHERE ' . $this->makeList( $conds, self::LIST_AND );
2194                 }
2195                 $sql .= ')';
2196
2197                 $this->query( $sql, $fname );
2198         }
2199
2200         public function textFieldSize( $table, $field ) {
2201                 $table = $this->tableName( $table );
2202                 $sql = "SHOW COLUMNS FROM $table LIKE \"$field\";";
2203                 $res = $this->query( $sql, __METHOD__ );
2204                 $row = $this->fetchObject( $res );
2205
2206                 $m = [];
2207
2208                 if ( preg_match( '/\((.*)\)/', $row->Type, $m ) ) {
2209                         $size = $m[1];
2210                 } else {
2211                         $size = -1;
2212                 }
2213
2214                 return $size;
2215         }
2216
2217         public function delete( $table, $conds, $fname = __METHOD__ ) {
2218                 if ( !$conds ) {
2219                         throw new DBUnexpectedError( $this, __METHOD__ . ' called with no conditions' );
2220                 }
2221
2222                 $table = $this->tableName( $table );
2223                 $sql = "DELETE FROM $table";
2224
2225                 if ( $conds != '*' ) {
2226                         if ( is_array( $conds ) ) {
2227                                 $conds = $this->makeList( $conds, self::LIST_AND );
2228                         }
2229                         $sql .= ' WHERE ' . $conds;
2230                 }
2231
2232                 return $this->query( $sql, $fname );
2233         }
2234
2235         public function insertSelect(
2236                 $destTable, $srcTable, $varMap, $conds,
2237                 $fname = __METHOD__, $insertOptions = [], $selectOptions = []
2238         ) {
2239                 if ( $this->cliMode ) {
2240                         // For massive migrations with downtime, we don't want to select everything
2241                         // into memory and OOM, so do all this native on the server side if possible.
2242                         return $this->nativeInsertSelect(
2243                                 $destTable,
2244                                 $srcTable,
2245                                 $varMap,
2246                                 $conds,
2247                                 $fname,
2248                                 $insertOptions,
2249                                 $selectOptions
2250                         );
2251                 }
2252
2253                 // For web requests, do a locking SELECT and then INSERT. This puts the SELECT burden
2254                 // on only the master (without needing row-based-replication). It also makes it easy to
2255                 // know how big the INSERT is going to be.
2256                 $fields = [];
2257                 foreach ( $varMap as $dstColumn => $sourceColumnOrSql ) {
2258                         $fields[] = $this->fieldNameWithAlias( $sourceColumnOrSql, $dstColumn );
2259                 }
2260                 $selectOptions[] = 'FOR UPDATE';
2261                 $res = $this->select( $srcTable, implode( ',', $fields ), $conds, $fname, $selectOptions );
2262                 if ( !$res ) {
2263                         return false;
2264                 }
2265
2266                 $rows = [];
2267                 foreach ( $res as $row ) {
2268                         $rows[] = (array)$row;
2269                 }
2270
2271                 return $this->insert( $destTable, $rows, $fname, $insertOptions );
2272         }
2273
2274         protected function nativeInsertSelect( $destTable, $srcTable, $varMap, $conds,
2275                 $fname = __METHOD__,
2276                 $insertOptions = [], $selectOptions = []
2277         ) {
2278                 $destTable = $this->tableName( $destTable );
2279
2280                 if ( !is_array( $insertOptions ) ) {
2281                         $insertOptions = [ $insertOptions ];
2282                 }
2283
2284                 $insertOptions = $this->makeInsertOptions( $insertOptions );
2285
2286                 if ( !is_array( $selectOptions ) ) {
2287                         $selectOptions = [ $selectOptions ];
2288                 }
2289
2290                 list( $startOpts, $useIndex, $tailOpts, $ignoreIndex ) = $this->makeSelectOptions(
2291                         $selectOptions );
2292
2293                 if ( is_array( $srcTable ) ) {
2294                         $srcTable = implode( ',', array_map( [ &$this, 'tableName' ], $srcTable ) );
2295                 } else {
2296                         $srcTable = $this->tableName( $srcTable );
2297                 }
2298
2299                 $sql = "INSERT $insertOptions" .
2300                         " INTO $destTable (" . implode( ',', array_keys( $varMap ) ) . ')' .
2301                         " SELECT $startOpts " . implode( ',', $varMap ) .
2302                         " FROM $srcTable $useIndex $ignoreIndex ";
2303
2304                 if ( $conds != '*' ) {
2305                         if ( is_array( $conds ) ) {
2306                                 $conds = $this->makeList( $conds, self::LIST_AND );
2307                         }
2308                         $sql .= " WHERE $conds";
2309                 }
2310
2311                 $sql .= " $tailOpts";
2312
2313                 return $this->query( $sql, $fname );
2314         }
2315
2316         /**
2317          * Construct a LIMIT query with optional offset. This is used for query
2318          * pages. The SQL should be adjusted so that only the first $limit rows
2319          * are returned. If $offset is provided as well, then the first $offset
2320          * rows should be discarded, and the next $limit rows should be returned.
2321          * If the result of the query is not ordered, then the rows to be returned
2322          * are theoretically arbitrary.
2323          *
2324          * $sql is expected to be a SELECT, if that makes a difference.
2325          *
2326          * The version provided by default works in MySQL and SQLite. It will very
2327          * likely need to be overridden for most other DBMSes.
2328          *
2329          * @param string $sql SQL query we will append the limit too
2330          * @param int $limit The SQL limit
2331          * @param int|bool $offset The SQL offset (default false)
2332          * @throws DBUnexpectedError
2333          * @return string
2334          */
2335         public function limitResult( $sql, $limit, $offset = false ) {
2336                 if ( !is_numeric( $limit ) ) {
2337                         throw new DBUnexpectedError( $this,
2338                                 "Invalid non-numeric limit passed to limitResult()\n" );
2339                 }
2340
2341                 return "$sql LIMIT "
2342                 . ( ( is_numeric( $offset ) && $offset != 0 ) ? "{$offset}," : "" )
2343                 . "{$limit} ";
2344         }
2345
2346         public function unionSupportsOrderAndLimit() {
2347                 return true; // True for almost every DB supported
2348         }
2349
2350         public function unionQueries( $sqls, $all ) {
2351                 $glue = $all ? ') UNION ALL (' : ') UNION (';
2352
2353                 return '(' . implode( $glue, $sqls ) . ')';
2354         }
2355
2356         public function conditional( $cond, $trueVal, $falseVal ) {
2357                 if ( is_array( $cond ) ) {
2358                         $cond = $this->makeList( $cond, self::LIST_AND );
2359                 }
2360
2361                 return " (CASE WHEN $cond THEN $trueVal ELSE $falseVal END) ";
2362         }
2363
2364         public function strreplace( $orig, $old, $new ) {
2365                 return "REPLACE({$orig}, {$old}, {$new})";
2366         }
2367
2368         public function getServerUptime() {
2369                 return 0;
2370         }
2371
2372         public function wasDeadlock() {
2373                 return false;
2374         }
2375
2376         public function wasLockTimeout() {
2377                 return false;
2378         }
2379
2380         public function wasErrorReissuable() {
2381                 return false;
2382         }
2383
2384         public function wasReadOnlyError() {
2385                 return false;
2386         }
2387
2388         /**
2389          * Do not use this method outside of Database/DBError classes
2390          *
2391          * @param integer|string $errno
2392          * @return bool Whether the given query error was a connection drop
2393          */
2394         public function wasConnectionError( $errno ) {
2395                 return false;
2396         }
2397
2398         public function deadlockLoop() {
2399                 $args = func_get_args();
2400                 $function = array_shift( $args );
2401                 $tries = self::DEADLOCK_TRIES;
2402
2403                 $this->begin( __METHOD__ );
2404
2405                 $retVal = null;
2406                 /** @var Exception $e */
2407                 $e = null;
2408                 do {
2409                         try {
2410                                 $retVal = call_user_func_array( $function, $args );
2411                                 break;
2412                         } catch ( DBQueryError $e ) {
2413                                 if ( $this->wasDeadlock() ) {
2414                                         // Retry after a randomized delay
2415                                         usleep( mt_rand( self::DEADLOCK_DELAY_MIN, self::DEADLOCK_DELAY_MAX ) );
2416                                 } else {
2417                                         // Throw the error back up
2418                                         throw $e;
2419                                 }
2420                         }
2421                 } while ( --$tries > 0 );
2422
2423                 if ( $tries <= 0 ) {
2424                         // Too many deadlocks; give up
2425                         $this->rollback( __METHOD__ );
2426                         throw $e;
2427                 } else {
2428                         $this->commit( __METHOD__ );
2429
2430                         return $retVal;
2431                 }
2432         }
2433
2434         public function masterPosWait( DBMasterPos $pos, $timeout ) {
2435                 # Real waits are implemented in the subclass.
2436                 return 0;
2437         }
2438
2439         public function getReplicaPos() {
2440                 # Stub
2441                 return false;
2442         }
2443
2444         public function getMasterPos() {
2445                 # Stub
2446                 return false;
2447         }
2448
2449         public function serverIsReadOnly() {
2450                 return false;
2451         }
2452
2453         final public function onTransactionResolution( callable $callback, $fname = __METHOD__ ) {
2454                 if ( !$this->mTrxLevel ) {
2455                         throw new DBUnexpectedError( $this, "No transaction is active." );
2456                 }
2457                 $this->mTrxEndCallbacks[] = [ $callback, $fname ];
2458         }
2459
2460         final public function onTransactionIdle( callable $callback, $fname = __METHOD__ ) {
2461                 $this->mTrxIdleCallbacks[] = [ $callback, $fname ];
2462                 if ( !$this->mTrxLevel ) {
2463                         $this->runOnTransactionIdleCallbacks( self::TRIGGER_IDLE );
2464                 }
2465         }
2466
2467         final public function onTransactionPreCommitOrIdle( callable $callback, $fname = __METHOD__ ) {
2468                 if ( $this->mTrxLevel ) {
2469                         $this->mTrxPreCommitCallbacks[] = [ $callback, $fname ];
2470                 } else {
2471                         // If no transaction is active, then make one for this callback
2472                         $this->startAtomic( __METHOD__ );
2473                         try {
2474                                 call_user_func( $callback );
2475                                 $this->endAtomic( __METHOD__ );
2476                         } catch ( Exception $e ) {
2477                                 $this->rollback( __METHOD__, self::FLUSHING_INTERNAL );
2478                                 throw $e;
2479                         }
2480                 }
2481         }
2482
2483         final public function setTransactionListener( $name, callable $callback = null ) {
2484                 if ( $callback ) {
2485                         $this->mTrxRecurringCallbacks[$name] = $callback;
2486                 } else {
2487                         unset( $this->mTrxRecurringCallbacks[$name] );
2488                 }
2489         }
2490
2491         /**
2492          * Whether to disable running of post-COMMIT/ROLLBACK callbacks
2493          *
2494          * This method should not be used outside of Database/LoadBalancer
2495          *
2496          * @param bool $suppress
2497          * @since 1.28
2498          */
2499         final public function setTrxEndCallbackSuppression( $suppress ) {
2500                 $this->mTrxEndCallbacksSuppressed = $suppress;
2501         }
2502
2503         /**
2504          * Actually run and consume any "on transaction idle/resolution" callbacks.
2505          *
2506          * This method should not be used outside of Database/LoadBalancer
2507          *
2508          * @param integer $trigger IDatabase::TRIGGER_* constant
2509          * @since 1.20
2510          * @throws Exception
2511          */
2512         public function runOnTransactionIdleCallbacks( $trigger ) {
2513                 if ( $this->mTrxEndCallbacksSuppressed ) {
2514                         return;
2515                 }
2516
2517                 $autoTrx = $this->getFlag( self::DBO_TRX ); // automatic begin() enabled?
2518                 /** @var Exception $e */
2519                 $e = null; // first exception
2520                 do { // callbacks may add callbacks :)
2521                         $callbacks = array_merge(
2522                                 $this->mTrxIdleCallbacks,
2523                                 $this->mTrxEndCallbacks // include "transaction resolution" callbacks
2524                         );
2525                         $this->mTrxIdleCallbacks = []; // consumed (and recursion guard)
2526                         $this->mTrxEndCallbacks = []; // consumed (recursion guard)
2527                         foreach ( $callbacks as $callback ) {
2528                                 try {
2529                                         list( $phpCallback ) = $callback;
2530                                         $this->clearFlag( self::DBO_TRX ); // make each query its own transaction
2531                                         call_user_func_array( $phpCallback, [ $trigger ] );
2532                                         if ( $autoTrx ) {
2533                                                 $this->setFlag( self::DBO_TRX ); // restore automatic begin()
2534                                         } else {
2535                                                 $this->clearFlag( self::DBO_TRX ); // restore auto-commit
2536                                         }
2537                                 } catch ( Exception $ex ) {
2538                                         call_user_func( $this->errorLogger, $ex );
2539                                         $e = $e ?: $ex;
2540                                         // Some callbacks may use startAtomic/endAtomic, so make sure
2541                                         // their transactions are ended so other callbacks don't fail
2542                                         if ( $this->trxLevel() ) {
2543                                                 $this->rollback( __METHOD__, self::FLUSHING_INTERNAL );
2544                                         }
2545                                 }
2546                         }
2547                 } while ( count( $this->mTrxIdleCallbacks ) );
2548
2549                 if ( $e instanceof Exception ) {
2550                         throw $e; // re-throw any first exception
2551                 }
2552         }
2553
2554         /**
2555          * Actually run and consume any "on transaction pre-commit" callbacks.
2556          *
2557          * This method should not be used outside of Database/LoadBalancer
2558          *
2559          * @since 1.22
2560          * @throws Exception
2561          */
2562         public function runOnTransactionPreCommitCallbacks() {
2563                 $e = null; // first exception
2564                 do { // callbacks may add callbacks :)
2565                         $callbacks = $this->mTrxPreCommitCallbacks;
2566                         $this->mTrxPreCommitCallbacks = []; // consumed (and recursion guard)
2567                         foreach ( $callbacks as $callback ) {
2568                                 try {
2569                                         list( $phpCallback ) = $callback;
2570                                         call_user_func( $phpCallback );
2571                                 } catch ( Exception $ex ) {
2572                                         call_user_func( $this->errorLogger, $ex );
2573                                         $e = $e ?: $ex;
2574                                 }
2575                         }
2576                 } while ( count( $this->mTrxPreCommitCallbacks ) );
2577
2578                 if ( $e instanceof Exception ) {
2579                         throw $e; // re-throw any first exception
2580                 }
2581         }
2582
2583         /**
2584          * Actually run any "transaction listener" callbacks.
2585          *
2586          * This method should not be used outside of Database/LoadBalancer
2587          *
2588          * @param integer $trigger IDatabase::TRIGGER_* constant
2589          * @throws Exception
2590          * @since 1.20
2591          */
2592         public function runTransactionListenerCallbacks( $trigger ) {
2593                 if ( $this->mTrxEndCallbacksSuppressed ) {
2594                         return;
2595                 }
2596
2597                 /** @var Exception $e */
2598                 $e = null; // first exception
2599
2600                 foreach ( $this->mTrxRecurringCallbacks as $phpCallback ) {
2601                         try {
2602                                 $phpCallback( $trigger, $this );
2603                         } catch ( Exception $ex ) {
2604                                 call_user_func( $this->errorLogger, $ex );
2605                                 $e = $e ?: $ex;
2606                         }
2607                 }
2608
2609                 if ( $e instanceof Exception ) {
2610                         throw $e; // re-throw any first exception
2611                 }
2612         }
2613
2614         final public function startAtomic( $fname = __METHOD__ ) {
2615                 if ( !$this->mTrxLevel ) {
2616                         $this->begin( $fname, self::TRANSACTION_INTERNAL );
2617                         // If DBO_TRX is set, a series of startAtomic/endAtomic pairs will result
2618                         // in all changes being in one transaction to keep requests transactional.
2619                         if ( !$this->getFlag( self::DBO_TRX ) ) {
2620                                 $this->mTrxAutomaticAtomic = true;
2621                         }
2622                 }
2623
2624                 $this->mTrxAtomicLevels[] = $fname;
2625         }
2626
2627         final public function endAtomic( $fname = __METHOD__ ) {
2628                 if ( !$this->mTrxLevel ) {
2629                         throw new DBUnexpectedError( $this, "No atomic transaction is open (got $fname)." );
2630                 }
2631                 if ( !$this->mTrxAtomicLevels ||
2632                         array_pop( $this->mTrxAtomicLevels ) !== $fname
2633                 ) {
2634                         throw new DBUnexpectedError( $this, "Invalid atomic section ended (got $fname)." );
2635                 }
2636
2637                 if ( !$this->mTrxAtomicLevels && $this->mTrxAutomaticAtomic ) {
2638                         $this->commit( $fname, self::FLUSHING_INTERNAL );
2639                 }
2640         }
2641
2642         final public function doAtomicSection( $fname, callable $callback ) {
2643                 $this->startAtomic( $fname );
2644                 try {
2645                         $res = call_user_func_array( $callback, [ $this, $fname ] );
2646                 } catch ( Exception $e ) {
2647                         $this->rollback( $fname, self::FLUSHING_INTERNAL );
2648                         throw $e;
2649                 }
2650                 $this->endAtomic( $fname );
2651
2652                 return $res;
2653         }
2654
2655         final public function begin( $fname = __METHOD__, $mode = self::TRANSACTION_EXPLICIT ) {
2656                 // Protect against mismatched atomic section, transaction nesting, and snapshot loss
2657                 if ( $this->mTrxLevel ) {
2658                         if ( $this->mTrxAtomicLevels ) {
2659                                 $levels = implode( ', ', $this->mTrxAtomicLevels );
2660                                 $msg = "$fname: Got explicit BEGIN while atomic section(s) $levels are open.";
2661                                 throw new DBUnexpectedError( $this, $msg );
2662                         } elseif ( !$this->mTrxAutomatic ) {
2663                                 $msg = "$fname: Explicit transaction already active (from {$this->mTrxFname}).";
2664                                 throw new DBUnexpectedError( $this, $msg );
2665                         } else {
2666                                 // @TODO: make this an exception at some point
2667                                 $msg = "$fname: Implicit transaction already active (from {$this->mTrxFname}).";
2668                                 $this->queryLogger->error( $msg );
2669                                 return; // join the main transaction set
2670                         }
2671                 } elseif ( $this->getFlag( self::DBO_TRX ) && $mode !== self::TRANSACTION_INTERNAL ) {
2672                         // @TODO: make this an exception at some point
2673                         $msg = "$fname: Implicit transaction expected (DBO_TRX set).";
2674                         $this->queryLogger->error( $msg );
2675                         return; // let any writes be in the main transaction
2676                 }
2677
2678                 // Avoid fatals if close() was called
2679                 $this->assertOpen();
2680
2681                 $this->doBegin( $fname );
2682                 $this->mTrxTimestamp = microtime( true );
2683                 $this->mTrxFname = $fname;
2684                 $this->mTrxDoneWrites = false;
2685                 $this->mTrxAutomaticAtomic = false;
2686                 $this->mTrxAtomicLevels = [];
2687                 $this->mTrxShortId = sprintf( '%06x', mt_rand( 0, 0xffffff ) );
2688                 $this->mTrxWriteDuration = 0.0;
2689                 $this->mTrxWriteQueryCount = 0;
2690                 $this->mTrxWriteAdjDuration = 0.0;
2691                 $this->mTrxWriteAdjQueryCount = 0;
2692                 $this->mTrxWriteCallers = [];
2693                 // First SELECT after BEGIN will establish the snapshot in REPEATABLE-READ.
2694                 // Get an estimate of the replica DB lag before then, treating estimate staleness
2695                 // as lag itself just to be safe
2696                 $status = $this->getApproximateLagStatus();
2697                 $this->mTrxReplicaLag = $status['lag'] + ( microtime( true ) - $status['since'] );
2698                 // T147697: make explicitTrxActive() return true until begin() finishes. This way, no
2699                 // caller will think its OK to muck around with the transaction just because startAtomic()
2700                 // has not yet completed (e.g. setting mTrxAtomicLevels).
2701                 $this->mTrxAutomatic = ( $mode === self::TRANSACTION_INTERNAL );
2702         }
2703
2704         /**
2705          * Issues the BEGIN command to the database server.
2706          *
2707          * @see Database::begin()
2708          * @param string $fname
2709          */
2710         protected function doBegin( $fname ) {
2711                 $this->query( 'BEGIN', $fname );
2712                 $this->mTrxLevel = 1;
2713         }
2714
2715         final public function commit( $fname = __METHOD__, $flush = '' ) {
2716                 if ( $this->mTrxLevel && $this->mTrxAtomicLevels ) {
2717                         // There are still atomic sections open. This cannot be ignored
2718                         $levels = implode( ', ', $this->mTrxAtomicLevels );
2719                         throw new DBUnexpectedError(
2720                                 $this,
2721                                 "$fname: Got COMMIT while atomic sections $levels are still open."
2722                         );
2723                 }
2724
2725                 if ( $flush === self::FLUSHING_INTERNAL || $flush === self::FLUSHING_ALL_PEERS ) {
2726                         if ( !$this->mTrxLevel ) {
2727                                 return; // nothing to do
2728                         } elseif ( !$this->mTrxAutomatic ) {
2729                                 throw new DBUnexpectedError(
2730                                         $this,
2731                                         "$fname: Flushing an explicit transaction, getting out of sync."
2732                                 );
2733                         }
2734                 } else {
2735                         if ( !$this->mTrxLevel ) {
2736                                 $this->queryLogger->error(
2737                                         "$fname: No transaction to commit, something got out of sync." );
2738                                 return; // nothing to do
2739                         } elseif ( $this->mTrxAutomatic ) {
2740                                 // @TODO: make this an exception at some point
2741                                 $msg = "$fname: Explicit commit of implicit transaction.";
2742                                 $this->queryLogger->error( $msg );
2743                                 return; // wait for the main transaction set commit round
2744                         }
2745                 }
2746
2747                 // Avoid fatals if close() was called
2748                 $this->assertOpen();
2749
2750                 $this->runOnTransactionPreCommitCallbacks();
2751                 $writeTime = $this->pendingWriteQueryDuration( self::ESTIMATE_DB_APPLY );
2752                 $this->doCommit( $fname );
2753                 if ( $this->mTrxDoneWrites ) {
2754                         $this->mDoneWrites = microtime( true );
2755                         $this->trxProfiler->transactionWritingOut(
2756                                 $this->mServer, $this->mDBname, $this->mTrxShortId, $writeTime );
2757                 }
2758
2759                 $this->runOnTransactionIdleCallbacks( self::TRIGGER_COMMIT );
2760                 $this->runTransactionListenerCallbacks( self::TRIGGER_COMMIT );
2761         }
2762
2763         /**
2764          * Issues the COMMIT command to the database server.
2765          *
2766          * @see Database::commit()
2767          * @param string $fname
2768          */
2769         protected function doCommit( $fname ) {
2770                 if ( $this->mTrxLevel ) {
2771                         $this->query( 'COMMIT', $fname );
2772                         $this->mTrxLevel = 0;
2773                 }
2774         }
2775
2776         final public function rollback( $fname = __METHOD__, $flush = '' ) {
2777                 if ( $flush === self::FLUSHING_INTERNAL || $flush === self::FLUSHING_ALL_PEERS ) {
2778                         if ( !$this->mTrxLevel ) {
2779                                 return; // nothing to do
2780                         }
2781                 } else {
2782                         if ( !$this->mTrxLevel ) {
2783                                 $this->queryLogger->error(
2784                                         "$fname: No transaction to rollback, something got out of sync." );
2785                                 return; // nothing to do
2786                         } elseif ( $this->getFlag( self::DBO_TRX ) ) {
2787                                 throw new DBUnexpectedError(
2788                                         $this,
2789                                         "$fname: Expected mass rollback of all peer databases (DBO_TRX set)."
2790                                 );
2791                         }
2792                 }
2793
2794                 // Avoid fatals if close() was called
2795                 $this->assertOpen();
2796
2797                 $this->doRollback( $fname );
2798                 $this->mTrxAtomicLevels = [];
2799                 if ( $this->mTrxDoneWrites ) {
2800                         $this->trxProfiler->transactionWritingOut(
2801                                 $this->mServer, $this->mDBname, $this->mTrxShortId );
2802                 }
2803
2804                 $this->mTrxIdleCallbacks = []; // clear
2805                 $this->mTrxPreCommitCallbacks = []; // clear
2806                 $this->runOnTransactionIdleCallbacks( self::TRIGGER_ROLLBACK );
2807                 $this->runTransactionListenerCallbacks( self::TRIGGER_ROLLBACK );
2808         }
2809
2810         /**
2811          * Issues the ROLLBACK command to the database server.
2812          *
2813          * @see Database::rollback()
2814          * @param string $fname
2815          */
2816         protected function doRollback( $fname ) {
2817                 if ( $this->mTrxLevel ) {
2818                         # Disconnects cause rollback anyway, so ignore those errors
2819                         $ignoreErrors = true;
2820                         $this->query( 'ROLLBACK', $fname, $ignoreErrors );
2821                         $this->mTrxLevel = 0;
2822                 }
2823         }
2824
2825         public function flushSnapshot( $fname = __METHOD__ ) {
2826                 if ( $this->writesOrCallbacksPending() || $this->explicitTrxActive() ) {
2827                         // This only flushes transactions to clear snapshots, not to write data
2828                         $fnames = implode( ', ', $this->pendingWriteAndCallbackCallers() );
2829                         throw new DBUnexpectedError(
2830                                 $this,
2831                                 "$fname: Cannot COMMIT to clear snapshot because writes are pending ($fnames)."
2832                         );
2833                 }
2834
2835                 $this->commit( $fname, self::FLUSHING_INTERNAL );
2836         }
2837
2838         public function explicitTrxActive() {
2839                 return $this->mTrxLevel && ( $this->mTrxAtomicLevels || !$this->mTrxAutomatic );
2840         }
2841
2842         /**
2843          * Creates a new table with structure copied from existing table
2844          * Note that unlike most database abstraction functions, this function does not
2845          * automatically append database prefix, because it works at a lower
2846          * abstraction level.
2847          * The table names passed to this function shall not be quoted (this
2848          * function calls addIdentifierQuotes when needed).
2849          *
2850          * @param string $oldName Name of table whose structure should be copied
2851          * @param string $newName Name of table to be created
2852          * @param bool $temporary Whether the new table should be temporary
2853          * @param string $fname Calling function name
2854          * @throws RuntimeException
2855          * @return bool True if operation was successful
2856          */
2857         public function duplicateTableStructure( $oldName, $newName, $temporary = false,
2858                 $fname = __METHOD__
2859         ) {
2860                 throw new RuntimeException( __METHOD__ . ' is not implemented in descendant class' );
2861         }
2862
2863         public function listTables( $prefix = null, $fname = __METHOD__ ) {
2864                 throw new RuntimeException( __METHOD__ . ' is not implemented in descendant class' );
2865         }
2866
2867         public function listViews( $prefix = null, $fname = __METHOD__ ) {
2868                 throw new RuntimeException( __METHOD__ . ' is not implemented in descendant class' );
2869         }
2870
2871         public function timestamp( $ts = 0 ) {
2872                 $t = new ConvertibleTimestamp( $ts );
2873                 // Let errors bubble up to avoid putting garbage in the DB
2874                 return $t->getTimestamp( TS_MW );
2875         }
2876
2877         public function timestampOrNull( $ts = null ) {
2878                 if ( is_null( $ts ) ) {
2879                         return null;
2880                 } else {
2881                         return $this->timestamp( $ts );
2882                 }
2883         }
2884
2885         /**
2886          * Take the result from a query, and wrap it in a ResultWrapper if
2887          * necessary. Boolean values are passed through as is, to indicate success
2888          * of write queries or failure.
2889          *
2890          * Once upon a time, Database::query() returned a bare MySQL result
2891          * resource, and it was necessary to call this function to convert it to
2892          * a wrapper. Nowadays, raw database objects are never exposed to external
2893          * callers, so this is unnecessary in external code.
2894          *
2895          * @param bool|ResultWrapper|resource|object $result
2896          * @return bool|ResultWrapper
2897          */
2898         protected function resultObject( $result ) {
2899                 if ( !$result ) {
2900                         return false;
2901                 } elseif ( $result instanceof ResultWrapper ) {
2902                         return $result;
2903                 } elseif ( $result === true ) {
2904                         // Successful write query
2905                         return $result;
2906                 } else {
2907                         return new ResultWrapper( $this, $result );
2908                 }
2909         }
2910
2911         public function ping( &$rtt = null ) {
2912                 // Avoid hitting the server if it was hit recently
2913                 if ( $this->isOpen() && ( microtime( true ) - $this->lastPing ) < self::PING_TTL ) {
2914                         if ( !func_num_args() || $this->mRTTEstimate > 0 ) {
2915                                 $rtt = $this->mRTTEstimate;
2916                                 return true; // don't care about $rtt
2917                         }
2918                 }
2919
2920                 // This will reconnect if possible or return false if not
2921                 $this->clearFlag( self::DBO_TRX, self::REMEMBER_PRIOR );
2922                 $ok = ( $this->query( self::PING_QUERY, __METHOD__, true ) !== false );
2923                 $this->restoreFlags( self::RESTORE_PRIOR );
2924
2925                 if ( $ok ) {
2926                         $rtt = $this->mRTTEstimate;
2927                 }
2928
2929                 return $ok;
2930         }
2931
2932         /**
2933          * @return bool
2934          */
2935         protected function reconnect() {
2936                 $this->closeConnection();
2937                 $this->mOpened = false;
2938                 $this->mConn = false;
2939                 try {
2940                         $this->open( $this->mServer, $this->mUser, $this->mPassword, $this->mDBname );
2941                         $this->lastPing = microtime( true );
2942                         $ok = true;
2943                 } catch ( DBConnectionError $e ) {
2944                         $ok = false;
2945                 }
2946
2947                 return $ok;
2948         }
2949
2950         public function getSessionLagStatus() {
2951                 return $this->getTransactionLagStatus() ?: $this->getApproximateLagStatus();
2952         }
2953
2954         /**
2955          * Get the replica DB lag when the current transaction started
2956          *
2957          * This is useful when transactions might use snapshot isolation
2958          * (e.g. REPEATABLE-READ in innodb), so the "real" lag of that data
2959          * is this lag plus transaction duration. If they don't, it is still
2960          * safe to be pessimistic. This returns null if there is no transaction.
2961          *
2962          * @return array|null ('lag': seconds or false on error, 'since': UNIX timestamp of BEGIN)
2963          * @since 1.27
2964          */
2965         protected function getTransactionLagStatus() {
2966                 return $this->mTrxLevel
2967                         ? [ 'lag' => $this->mTrxReplicaLag, 'since' => $this->trxTimestamp() ]
2968                         : null;
2969         }
2970
2971         /**
2972          * Get a replica DB lag estimate for this server
2973          *
2974          * @return array ('lag': seconds or false on error, 'since': UNIX timestamp of estimate)
2975          * @since 1.27
2976          */
2977         protected function getApproximateLagStatus() {
2978                 return [
2979                         'lag'   => $this->getLBInfo( 'replica' ) ? $this->getLag() : 0,
2980                         'since' => microtime( true )
2981                 ];
2982         }
2983
2984         /**
2985          * Merge the result of getSessionLagStatus() for several DBs
2986          * using the most pessimistic values to estimate the lag of
2987          * any data derived from them in combination
2988          *
2989          * This is information is useful for caching modules
2990          *
2991          * @see WANObjectCache::set()
2992          * @see WANObjectCache::getWithSetCallback()
2993          *
2994          * @param IDatabase $db1
2995          * @param IDatabase ...
2996          * @return array Map of values:
2997          *   - lag: highest lag of any of the DBs or false on error (e.g. replication stopped)
2998          *   - since: oldest UNIX timestamp of any of the DB lag estimates
2999          *   - pending: whether any of the DBs have uncommitted changes
3000          * @since 1.27
3001          */
3002         public static function getCacheSetOptions( IDatabase $db1 ) {
3003                 $res = [ 'lag' => 0, 'since' => INF, 'pending' => false ];
3004                 foreach ( func_get_args() as $db ) {
3005                         /** @var IDatabase $db */
3006                         $status = $db->getSessionLagStatus();
3007                         if ( $status['lag'] === false ) {
3008                                 $res['lag'] = false;
3009                         } elseif ( $res['lag'] !== false ) {
3010                                 $res['lag'] = max( $res['lag'], $status['lag'] );
3011                         }
3012                         $res['since'] = min( $res['since'], $status['since'] );
3013                         $res['pending'] = $res['pending'] ?: $db->writesPending();
3014                 }
3015
3016                 return $res;
3017         }
3018
3019         public function getLag() {
3020                 return 0;
3021         }
3022
3023         public function maxListLen() {
3024                 return 0;
3025         }
3026
3027         public function encodeBlob( $b ) {
3028                 return $b;
3029         }
3030
3031         public function decodeBlob( $b ) {
3032                 if ( $b instanceof Blob ) {
3033                         $b = $b->fetch();
3034                 }
3035                 return $b;
3036         }
3037
3038         public function setSessionOptions( array $options ) {
3039         }
3040
3041         public function sourceFile(
3042                 $filename,
3043                 callable $lineCallback = null,
3044                 callable $resultCallback = null,
3045                 $fname = false,
3046                 callable $inputCallback = null
3047         ) {
3048                 MediaWiki\suppressWarnings();
3049                 $fp = fopen( $filename, 'r' );
3050                 MediaWiki\restoreWarnings();
3051
3052                 if ( false === $fp ) {
3053                         throw new RuntimeException( "Could not open \"{$filename}\".\n" );
3054                 }
3055
3056                 if ( !$fname ) {
3057                         $fname = __METHOD__ . "( $filename )";
3058                 }
3059
3060                 try {
3061                         $error = $this->sourceStream(
3062                                 $fp, $lineCallback, $resultCallback, $fname, $inputCallback );
3063                 } catch ( Exception $e ) {
3064                         fclose( $fp );
3065                         throw $e;
3066                 }
3067
3068                 fclose( $fp );
3069
3070                 return $error;
3071         }
3072
3073         public function setSchemaVars( $vars ) {
3074                 $this->mSchemaVars = $vars;
3075         }
3076
3077         public function sourceStream(
3078                 $fp,
3079                 callable $lineCallback = null,
3080                 callable $resultCallback = null,
3081                 $fname = __METHOD__,
3082                 callable $inputCallback = null
3083         ) {
3084                 $cmd = '';
3085
3086                 while ( !feof( $fp ) ) {
3087                         if ( $lineCallback ) {
3088                                 call_user_func( $lineCallback );
3089                         }
3090
3091                         $line = trim( fgets( $fp ) );
3092
3093                         if ( $line == '' ) {
3094                                 continue;
3095                         }
3096
3097                         if ( '-' == $line[0] && '-' == $line[1] ) {
3098                                 continue;
3099                         }
3100
3101                         if ( $cmd != '' ) {
3102                                 $cmd .= ' ';
3103                         }
3104
3105                         $done = $this->streamStatementEnd( $cmd, $line );
3106
3107                         $cmd .= "$line\n";
3108
3109                         if ( $done || feof( $fp ) ) {
3110                                 $cmd = $this->replaceVars( $cmd );
3111
3112                                 if ( !$inputCallback || call_user_func( $inputCallback, $cmd ) ) {
3113                                         $res = $this->query( $cmd, $fname );
3114
3115                                         if ( $resultCallback ) {
3116                                                 call_user_func( $resultCallback, $res, $this );
3117                                         }
3118
3119                                         if ( false === $res ) {
3120                                                 $err = $this->lastError();
3121
3122                                                 return "Query \"{$cmd}\" failed with error code \"$err\".\n";
3123                                         }
3124                                 }
3125                                 $cmd = '';
3126                         }
3127                 }
3128
3129                 return true;
3130         }
3131
3132         /**
3133          * Called by sourceStream() to check if we've reached a statement end
3134          *
3135          * @param string &$sql SQL assembled so far
3136          * @param string &$newLine New line about to be added to $sql
3137          * @return bool Whether $newLine contains end of the statement
3138          */
3139         public function streamStatementEnd( &$sql, &$newLine ) {
3140                 if ( $this->delimiter ) {
3141                         $prev = $newLine;
3142                         $newLine = preg_replace(
3143                                 '/' . preg_quote( $this->delimiter, '/' ) . '$/', '', $newLine );
3144                         if ( $newLine != $prev ) {
3145                                 return true;
3146                         }
3147                 }
3148
3149                 return false;
3150         }
3151
3152         /**
3153          * Database independent variable replacement. Replaces a set of variables
3154          * in an SQL statement with their contents as given by $this->getSchemaVars().
3155          *
3156          * Supports '{$var}' `{$var}` and / *$var* / (without the spaces) style variables.
3157          *
3158          * - '{$var}' should be used for text and is passed through the database's
3159          *   addQuotes method.
3160          * - `{$var}` should be used for identifiers (e.g. table and database names).
3161          *   It is passed through the database's addIdentifierQuotes method which
3162          *   can be overridden if the database uses something other than backticks.
3163          * - / *_* / or / *$wgDBprefix* / passes the name that follows through the
3164          *   database's tableName method.
3165          * - / *i* / passes the name that follows through the database's indexName method.
3166          * - In all other cases, / *$var* / is left unencoded. Except for table options,
3167          *   its use should be avoided. In 1.24 and older, string encoding was applied.
3168          *
3169          * @param string $ins SQL statement to replace variables in
3170          * @return string The new SQL statement with variables replaced
3171          */
3172         protected function replaceVars( $ins ) {
3173                 $vars = $this->getSchemaVars();
3174                 return preg_replace_callback(
3175                         '!
3176                                 /\* (\$wgDBprefix|[_i]) \*/ (\w*) | # 1-2. tableName, indexName
3177                                 \'\{\$ (\w+) }\'                  | # 3. addQuotes
3178                                 `\{\$ (\w+) }`                    | # 4. addIdentifierQuotes
3179                                 /\*\$ (\w+) \*/                     # 5. leave unencoded
3180                         !x',
3181                         function ( $m ) use ( $vars ) {
3182                                 // Note: Because of <https://bugs.php.net/bug.php?id=51881>,
3183                                 // check for both nonexistent keys *and* the empty string.
3184                                 if ( isset( $m[1] ) && $m[1] !== '' ) {
3185                                         if ( $m[1] === 'i' ) {
3186                                                 return $this->indexName( $m[2] );
3187                                         } else {
3188                                                 return $this->tableName( $m[2] );
3189                                         }
3190                                 } elseif ( isset( $m[3] ) && $m[3] !== '' && array_key_exists( $m[3], $vars ) ) {
3191                                         return $this->addQuotes( $vars[$m[3]] );
3192                                 } elseif ( isset( $m[4] ) && $m[4] !== '' && array_key_exists( $m[4], $vars ) ) {
3193                                         return $this->addIdentifierQuotes( $vars[$m[4]] );
3194                                 } elseif ( isset( $m[5] ) && $m[5] !== '' && array_key_exists( $m[5], $vars ) ) {
3195                                         return $vars[$m[5]];
3196                                 } else {
3197                                         return $m[0];
3198                                 }
3199                         },
3200                         $ins
3201                 );
3202         }
3203
3204         /**
3205          * Get schema variables. If none have been set via setSchemaVars(), then
3206          * use some defaults from the current object.
3207          *
3208          * @return array
3209          */
3210         protected function getSchemaVars() {
3211                 if ( $this->mSchemaVars ) {
3212                         return $this->mSchemaVars;
3213                 } else {
3214                         return $this->getDefaultSchemaVars();
3215                 }
3216         }
3217
3218         /**
3219          * Get schema variables to use if none have been set via setSchemaVars().
3220          *
3221          * Override this in derived classes to provide variables for tables.sql
3222          * and SQL patch files.
3223          *
3224          * @return array
3225          */
3226         protected function getDefaultSchemaVars() {
3227                 return [];
3228         }
3229
3230         public function lockIsFree( $lockName, $method ) {
3231                 return true;
3232         }
3233
3234         public function lock( $lockName, $method, $timeout = 5 ) {
3235                 $this->mNamedLocksHeld[$lockName] = 1;
3236
3237                 return true;
3238         }
3239
3240         public function unlock( $lockName, $method ) {
3241                 unset( $this->mNamedLocksHeld[$lockName] );
3242
3243                 return true;
3244         }
3245
3246         public function getScopedLockAndFlush( $lockKey, $fname, $timeout ) {
3247                 if ( $this->writesOrCallbacksPending() ) {
3248                         // This only flushes transactions to clear snapshots, not to write data
3249                         $fnames = implode( ', ', $this->pendingWriteAndCallbackCallers() );
3250                         throw new DBUnexpectedError(
3251                                 $this,
3252                                 "$fname: Cannot COMMIT to clear snapshot because writes are pending ($fnames)."
3253                         );
3254                 }
3255
3256                 if ( !$this->lock( $lockKey, $fname, $timeout ) ) {
3257                         return null;
3258                 }
3259
3260                 $unlocker = new ScopedCallback( function () use ( $lockKey, $fname ) {
3261                         if ( $this->trxLevel() ) {
3262                                 // There is a good chance an exception was thrown, causing any early return
3263                                 // from the caller. Let any error handler get a chance to issue rollback().
3264                                 // If there isn't one, let the error bubble up and trigger server-side rollback.
3265                                 $this->onTransactionResolution(
3266                                         function () use ( $lockKey, $fname ) {
3267                                                 $this->unlock( $lockKey, $fname );
3268                                         },
3269                                         $fname
3270                                 );
3271                         } else {
3272                                 $this->unlock( $lockKey, $fname );
3273                         }
3274                 } );
3275
3276                 $this->commit( $fname, self::FLUSHING_INTERNAL );
3277
3278                 return $unlocker;
3279         }
3280
3281         public function namedLocksEnqueue() {
3282                 return false;
3283         }
3284
3285         /**
3286          * Lock specific tables
3287          *
3288          * @param array $read Array of tables to lock for read access
3289          * @param array $write Array of tables to lock for write access
3290          * @param string $method Name of caller
3291          * @param bool $lowPriority Whether to indicate writes to be LOW PRIORITY
3292          * @return bool
3293          */
3294         public function lockTables( $read, $write, $method, $lowPriority = true ) {
3295                 return true;
3296         }
3297
3298         /**
3299          * Unlock specific tables
3300          *
3301          * @param string $method The caller
3302          * @return bool
3303          */
3304         public function unlockTables( $method ) {
3305                 return true;
3306         }
3307
3308         /**
3309          * Delete a table
3310          * @param string $tableName
3311          * @param string $fName
3312          * @return bool|ResultWrapper
3313          * @since 1.18
3314          */
3315         public function dropTable( $tableName, $fName = __METHOD__ ) {
3316                 if ( !$this->tableExists( $tableName, $fName ) ) {
3317                         return false;
3318                 }
3319                 $sql = "DROP TABLE " . $this->tableName( $tableName ) . " CASCADE";
3320
3321                 return $this->query( $sql, $fName );
3322         }
3323
3324         public function getInfinity() {
3325                 return 'infinity';
3326         }
3327
3328         public function encodeExpiry( $expiry ) {
3329                 return ( $expiry == '' || $expiry == 'infinity' || $expiry == $this->getInfinity() )
3330                         ? $this->getInfinity()
3331                         : $this->timestamp( $expiry );
3332         }
3333
3334         public function decodeExpiry( $expiry, $format = TS_MW ) {
3335                 if ( $expiry == '' || $expiry == 'infinity' || $expiry == $this->getInfinity() ) {
3336                         return 'infinity';
3337                 }
3338
3339                 return ConvertibleTimestamp::convert( $format, $expiry );
3340         }
3341
3342         public function setBigSelects( $value = true ) {
3343                 // no-op
3344         }
3345
3346         public function isReadOnly() {
3347                 return ( $this->getReadOnlyReason() !== false );
3348         }
3349
3350         /**
3351          * @return string|bool Reason this DB is read-only or false if it is not
3352          */
3353         protected function getReadOnlyReason() {
3354                 $reason = $this->getLBInfo( 'readOnlyReason' );
3355
3356                 return is_string( $reason ) ? $reason : false;
3357         }
3358
3359         public function setTableAliases( array $aliases ) {
3360                 $this->tableAliases = $aliases;
3361         }
3362
3363         /**
3364          * @return bool Whether a DB user is required to access the DB
3365          * @since 1.28
3366          */
3367         protected function requiresDatabaseUser() {
3368                 return true;
3369         }
3370
3371         /**
3372          * @since 1.19
3373          * @return string
3374          */
3375         public function __toString() {
3376                 return (string)$this->mConn;
3377         }
3378
3379         /**
3380          * Make sure that copies do not share the same client binding handle
3381          * @throws DBConnectionError
3382          */
3383         public function __clone() {
3384                 $this->connLogger->warning(
3385                         "Cloning " . get_class( $this ) . " is not recomended; forking connection:\n" .
3386                         ( new RuntimeException() )->getTraceAsString()
3387                 );
3388
3389                 if ( $this->isOpen() ) {
3390                         // Open a new connection resource without messing with the old one
3391                         $this->mOpened = false;
3392                         $this->mConn = false;
3393                         $this->mTrxEndCallbacks = []; // don't copy
3394                         $this->handleSessionLoss(); // no trx or locks anymore
3395                         $this->open( $this->mServer, $this->mUser, $this->mPassword, $this->mDBname );
3396                         $this->lastPing = microtime( true );
3397                 }
3398         }
3399
3400         /**
3401          * Called by serialize. Throw an exception when DB connection is serialized.
3402          * This causes problems on some database engines because the connection is
3403          * not restored on unserialize.
3404          */
3405         public function __sleep() {
3406                 throw new RuntimeException( 'Database serialization may cause problems, since ' .
3407                         'the connection is not restored on wakeup.' );
3408         }
3409
3410         /**
3411          * Run a few simple sanity checks and close dangling connections
3412          */
3413         public function __destruct() {
3414                 if ( $this->mTrxLevel && $this->mTrxDoneWrites ) {
3415                         trigger_error( "Uncommitted DB writes (transaction from {$this->mTrxFname})." );
3416                 }
3417
3418                 $danglingWriters = $this->pendingWriteAndCallbackCallers();
3419                 if ( $danglingWriters ) {
3420                         $fnames = implode( ', ', $danglingWriters );
3421                         trigger_error( "DB transaction writes or callbacks still pending ($fnames)." );
3422                 }
3423
3424                 if ( $this->mConn ) {
3425                         // Avoid connection leaks for sanity
3426                         $this->closeConnection();
3427                         $this->mConn = false;
3428                         $this->mOpened = false;
3429                 }
3430         }
3431 }
3432
3433 class_alias( 'Database', 'DatabaseBase' );