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 namespace Wikimedia\Rdbms;
  27
  28 use Psr\Log\LoggerAwareInterface;
  29 use Psr\Log\LoggerInterface;
  30 use Wikimedia\ScopedCallback;
  31 use Wikimedia\Timestamp\ConvertibleTimestamp;
  32 use MediaWiki;
  33 use BagOStuff;
  34 use HashBagOStuff;
  35 use InvalidArgumentException;
  36 use Exception;
  37 use RuntimeException;
  38
  39 /**
  40  * Relational database abstraction object
  41  *
  42  * @ingroup Database
  43  * @since 1.28
  44  */
  45 abstract class Database implements IDatabase, IMaintainableDatabase, LoggerAwareInterface {
  46         /** Number of times to re-try an operation in case of deadlock */
  47         const DEADLOCK_TRIES = 4;
  48         /** Minimum time to wait before retry, in microseconds */
  49         const DEADLOCK_DELAY_MIN = 500000;
  50         /** Maximum time to wait before retry */
  51         const DEADLOCK_DELAY_MAX = 1500000;
  52
  53         /** How long before it is worth doing a dummy query to test the connection */
  54         const PING_TTL = 1.0;
  55         const PING_QUERY = 'SELECT 1 AS ping';
  56
  57         const TINY_WRITE_SEC = 0.010;
  58         const SLOW_WRITE_SEC = 0.500;
  59         const SMALL_WRITE_ROWS = 100;
  60
  61         /** @var string SQL query */
  62         protected $mLastQuery = '';
  63         /** @var float|bool UNIX timestamp of last write query */
  64         protected $mLastWriteTime = false;
  65         /** @var string|bool */
  66         protected $mPHPError = false;
  67         /** @var string */
  68         protected $mServer;
  69         /** @var string */
  70         protected $mUser;
  71         /** @var string */
  72         protected $mPassword;
  73         /** @var string */
  74         protected $mDBname;
  75         /** @var array[] $aliases Map of (table => (dbname, schema, prefix) map) */
  76         protected $tableAliases = [];
  77         /** @var bool Whether this PHP instance is for a CLI script */
  78         protected $cliMode;
  79         /** @var string Agent name for query profiling */
  80         protected $agent;
  81
  82         /** @var BagOStuff APC cache */
  83         protected $srvCache;
  84         /** @var LoggerInterface */
  85         protected $connLogger;
  86         /** @var LoggerInterface */
  87         protected $queryLogger;
  88         /** @var callback Error logging callback */
  89         protected $errorLogger;
  90
  91         /** @var resource|null Database connection */
  92         protected $mConn = null;
  93         /** @var bool */
  94         protected $mOpened = false;
  95
  96         /** @var array[] List of (callable, method name) */
  97         protected $mTrxIdleCallbacks = [];
  98         /** @var array[] List of (callable, method name) */
  99         protected $mTrxPreCommitCallbacks = [];
 100         /** @var array[] List of (callable, method name) */
 101         protected $mTrxEndCallbacks = [];
 102         /** @var callable[] Map of (name => callable) */
 103         protected $mTrxRecurringCallbacks = [];
 104         /** @var bool Whether to suppress triggering of transaction end callbacks */
 105         protected $mTrxEndCallbacksSuppressed = false;
 106
 107         /** @var string */
 108         protected $mTablePrefix = '';
 109         /** @var string */
 110         protected $mSchema = '';
 111         /** @var int */
 112         protected $mFlags;
 113         /** @var array */
 114         protected $mLBInfo = [];
 115         /** @var bool|null */
 116         protected $mDefaultBigSelects = null;
 117         /** @var array|bool */
 118         protected $mSchemaVars = false;
 119         /** @var array */
 120         protected $mSessionVars = [];
 121         /** @var array|null */
 122         protected $preparedArgs;
 123         /** @var string|bool|null Stashed value of html_errors INI setting */
 124         protected $htmlErrors;
 125         /** @var string */
 126         protected $delimiter = ';';
 127         /** @var DatabaseDomain */
 128         protected $currentDomain;
 129
 130         /**
 131          * Either 1 if a transaction is active or 0 otherwise.
 132          * The other Trx fields may not be meaningfull if this is 0.
 133          *
 134          * @var int
 135          */
 136         protected $mTrxLevel = 0;
 137         /**
 138          * Either a short hexidecimal string if a transaction is active or ""
 139          *
 140          * @var string
 141          * @see Database::mTrxLevel
 142          */
 143         protected $mTrxShortId = '';
 144         /**
 145          * The UNIX time that the transaction started. Callers can assume that if
 146          * snapshot isolation is used, then the data is *at least* up to date to that
 147          * point (possibly more up-to-date since the first SELECT defines the snapshot).
 148          *
 149          * @var float|null
 150          * @see Database::mTrxLevel
 151          */
 152         private $mTrxTimestamp = null;
 153         /** @var float Lag estimate at the time of BEGIN */
 154         private $mTrxReplicaLag = null;
 155         /**
 156          * Remembers the function name given for starting the most recent transaction via begin().
 157          * Used to provide additional context for error reporting.
 158          *
 159          * @var string
 160          * @see Database::mTrxLevel
 161          */
 162         private $mTrxFname = null;
 163         /**
 164          * Record if possible write queries were done in the last transaction started
 165          *
 166          * @var bool
 167          * @see Database::mTrxLevel
 168          */
 169         private $mTrxDoneWrites = false;
 170         /**
 171          * Record if the current transaction was started implicitly due to DBO_TRX being set.
 172          *
 173          * @var bool
 174          * @see Database::mTrxLevel
 175          */
 176         private $mTrxAutomatic = false;
 177         /**
 178          * Array of levels of atomicity within transactions
 179          *
 180          * @var array
 181          */
 182         private $mTrxAtomicLevels = [];
 183         /**
 184          * Record if the current transaction was started implicitly by Database::startAtomic
 185          *
 186          * @var bool
 187          */
 188         private $mTrxAutomaticAtomic = false;
 189         /**
 190          * Track the write query callers of the current transaction
 191          *
 192          * @var string[]
 193          */
 194         private $mTrxWriteCallers = [];
 195         /**
 196          * @var float Seconds spent in write queries for the current transaction
 197          */
 198         private $mTrxWriteDuration = 0.0;
 199         /**
 200          * @var int Number of write queries for the current transaction
 201          */
 202         private $mTrxWriteQueryCount = 0;
 203         /**
 204          * @var int Number of rows affected by write queries for the current transaction
 205          */
 206         private $mTrxWriteAffectedRows = 0;
 207         /**
 208          * @var float Like mTrxWriteQueryCount but excludes lock-bound, easy to replicate, queries
 209          */
 210         private $mTrxWriteAdjDuration = 0.0;
 211         /**
 212          * @var int Number of write queries counted in mTrxWriteAdjDuration
 213          */
 214         private $mTrxWriteAdjQueryCount = 0;
 215         /**
 216          * @var float RTT time estimate
 217          */
 218         private $mRTTEstimate = 0.0;
 219
 220         /** @var array Map of (name => 1) for locks obtained via lock() */
 221         private $mNamedLocksHeld = [];
 222         /** @var array Map of (table name => 1) for TEMPORARY tables */
 223         protected $mSessionTempTables = [];
 224
 225         /** @var IDatabase|null Lazy handle to the master DB this server replicates from */
 226         private $lazyMasterHandle;
 227
 228         /** @var float UNIX timestamp */
 229         protected $lastPing = 0.0;
 230
 231         /** @var int[] Prior mFlags values */
 232         private $priorFlags = [];
 233
 234         /** @var object|string Class name or object With profileIn/profileOut methods */
 235         protected $profiler;
 236         /** @var TransactionProfiler */
 237         protected $trxProfiler;
 238
 239         /**
 240          * Constructor and database handle and attempt to connect to the DB server
 241          *
 242          * IDatabase classes should not be constructed directly in external
 243          * code. Database::factory() should be used instead.
 244          *
 245          * @param array $params Parameters passed from Database::factory()
 246          */
 247         function __construct( array $params ) {
 248                 $server = $params['host'];
 249                 $user = $params['user'];
 250                 $password = $params['password'];
 251                 $dbName = $params['dbname'];
 252
 253                 $this->mSchema = $params['schema'];
 254                 $this->mTablePrefix = $params['tablePrefix'];
 255
 256                 $this->cliMode = $params['cliMode'];
 257                 // Agent name is added to SQL queries in a comment, so make sure it can't break out
 258                 $this->agent = str_replace( '/', '-', $params['agent'] );
 259
 260                 $this->mFlags = $params['flags'];
 261                 if ( $this->mFlags & self::DBO_DEFAULT ) {
 262                         if ( $this->cliMode ) {
 263                                 $this->mFlags &= ~self::DBO_TRX;
 264                         } else {
 265                                 $this->mFlags |= self::DBO_TRX;
 266                         }
 267                 }
 268
 269                 $this->mSessionVars = $params['variables'];
 270
 271                 $this->srvCache = isset( $params['srvCache'] )
 272                         ? $params['srvCache']
 273                         : new HashBagOStuff();
 274
 275                 $this->profiler = $params['profiler'];
 276                 $this->trxProfiler = $params['trxProfiler'];
 277                 $this->connLogger = $params['connLogger'];
 278                 $this->queryLogger = $params['queryLogger'];
 279                 $this->errorLogger = $params['errorLogger'];
 280
 281                 // Set initial dummy domain until open() sets the final DB/prefix
 282                 $this->currentDomain = DatabaseDomain::newUnspecified();
 283
 284                 if ( $user ) {
 285                         $this->open( $server, $user, $password, $dbName );
 286                 } elseif ( $this->requiresDatabaseUser() ) {
 287                         throw new InvalidArgumentException( "No database user provided." );
 288                 }
 289
 290                 // Set the domain object after open() sets the relevant fields
 291                 if ( $this->mDBname != '' ) {
 292                         // Domains with server scope but a table prefix are not used by IDatabase classes
 293                         $this->currentDomain = new DatabaseDomain( $this->mDBname, null, $this->mTablePrefix );
 294                 }
 295         }
 296
 297         /**
 298          * Construct a Database subclass instance given a database type and parameters
 299          *
 300          * This also connects to the database immediately upon object construction
 301          *
 302          * @param string $dbType A possible DB type (sqlite, mysql, postgres)
 303          * @param array $p Parameter map with keys:
 304          *   - host : The hostname of the DB server
 305          *   - user : The name of the database user the client operates under
 306          *   - password : The password for the database user
 307          *   - dbname : The name of the database to use where queries do not specify one.
 308          *      The database must exist or an error might be thrown. Setting this to the empty string
 309          *      will avoid any such errors and make the handle have no implicit database scope. This is
 310          *      useful for queries like SHOW STATUS, CREATE DATABASE, or DROP DATABASE. Note that a
 311          *      "database" in Postgres is rougly equivalent to an entire MySQL server. This the domain
 312          *      in which user names and such are defined, e.g. users are database-specific in Postgres.
 313          *   - schema : The database schema to use (if supported). A "schema" in Postgres is roughly
 314          *      equivalent to a "database" in MySQL. Note that MySQL and SQLite do not use schemas.
 315          *   - tablePrefix : Optional table prefix that is implicitly added on to all table names
 316          *      recognized in queries. This can be used in place of schemas for handle site farms.
 317          *   - flags : Optional bitfield of DBO_* constants that define connection, protocol,
 318          *      buffering, and transaction behavior. It is STRONGLY adviced to leave the DBO_DEFAULT
 319          *      flag in place UNLESS this this database simply acts as a key/value store.
 320          *   - driver: Optional name of a specific DB client driver. For MySQL, there is the old
 321          *      'mysql' driver and the newer 'mysqli' driver.
 322          *   - variables: Optional map of session variables to set after connecting. This can be
 323          *      used to adjust lock timeouts or encoding modes and the like.
 324          *   - connLogger: Optional PSR-3 logger interface instance.
 325          *   - queryLogger: Optional PSR-3 logger interface instance.
 326          *   - profiler: Optional class name or object with profileIn()/profileOut() methods.
 327          *      These will be called in query(), using a simplified version of the SQL that also
 328          *      includes the agent as a SQL comment.
 329          *   - trxProfiler: Optional TransactionProfiler instance.
 330          *   - errorLogger: Optional callback that takes an Exception and logs it.
 331          *   - cliMode: Whether to consider the execution context that of a CLI script.
 332          *   - agent: Optional name used to identify the end-user in query profiling/logging.
 333          *   - srvCache: Optional BagOStuff instance to an APC-style cache.
 334          * @return Database|null If the database driver or extension cannot be found
 335          * @throws InvalidArgumentException If the database driver or extension cannot be found
 336          * @since 1.18
 337          */
 338         final public static function factory( $dbType, $p = [] ) {
 339                 static $canonicalDBTypes = [
 340                         'mysql' => [ 'mysqli', 'mysql' ],
 341                         'postgres' => [],
 342                         'sqlite' => [],
 343                         'oracle' => [],
 344                         'mssql' => [],
 345                 ];
 346                 static $classAliases = [
 347                         'DatabaseMssql' => DatabaseMssql::class,
 348                         'DatabaseMysql' => DatabaseMysql::class,
 349                         'DatabaseMysqli' => DatabaseMysqli::class,
 350                         'DatabaseSqlite' => DatabaseSqlite::class,
 351                         'DatabasePostgres' => DatabasePostgres::class
 352                 ];
 353
 354                 $driver = false;
 355                 $dbType = strtolower( $dbType );
 356                 if ( isset( $canonicalDBTypes[$dbType] ) && $canonicalDBTypes[$dbType] ) {
 357                         $possibleDrivers = $canonicalDBTypes[$dbType];
 358                         if ( !empty( $p['driver'] ) ) {
 359                                 if ( in_array( $p['driver'], $possibleDrivers ) ) {
 360                                         $driver = $p['driver'];
 361                                 } else {
 362                                         throw new InvalidArgumentException( __METHOD__ .
 363                                                 " type '$dbType' does not support driver '{$p['driver']}'" );
 364                                 }
 365                         } else {
 366                                 foreach ( $possibleDrivers as $posDriver ) {
 367                                         if ( extension_loaded( $posDriver ) ) {
 368                                                 $driver = $posDriver;
 369                                                 break;
 370                                         }
 371                                 }
 372                         }
 373                 } else {
 374                         $driver = $dbType;
 375                 }
 376
 377                 if ( $driver === false || $driver === '' ) {
 378                         throw new InvalidArgumentException( __METHOD__ .
 379                                 " no viable database extension found for type '$dbType'" );
 380                 }
 381
 382                 $class = 'Database' . ucfirst( $driver );
 383                 if ( isset( $classAliases[$class] ) ) {
 384                         $class = $classAliases[$class];
 385                 }
 386
 387                 if ( class_exists( $class ) && is_subclass_of( $class, IDatabase::class ) ) {
 388                         // Resolve some defaults for b/c
 389                         $p['host'] = isset( $p['host'] ) ? $p['host'] : false;
 390                         $p['user'] = isset( $p['user'] ) ? $p['user'] : false;
 391                         $p['password'] = isset( $p['password'] ) ? $p['password'] : false;
 392                         $p['dbname'] = isset( $p['dbname'] ) ? $p['dbname'] : false;
 393                         $p['flags'] = isset( $p['flags'] ) ? $p['flags'] : 0;
 394                         $p['variables'] = isset( $p['variables'] ) ? $p['variables'] : [];
 395                         $p['tablePrefix'] = isset( $p['tablePrefix'] ) ? $p['tablePrefix'] : '';
 396                         $p['schema'] = isset( $p['schema'] ) ? $p['schema'] : '';
 397                         $p['cliMode'] = isset( $p['cliMode'] ) ? $p['cliMode'] : ( PHP_SAPI === 'cli' );
 398                         $p['agent'] = isset( $p['agent'] ) ? $p['agent'] : '';
 399                         if ( !isset( $p['connLogger'] ) ) {
 400                                 $p['connLogger'] = new \Psr\Log\NullLogger();
 401                         }
 402                         if ( !isset( $p['queryLogger'] ) ) {
 403                                 $p['queryLogger'] = new \Psr\Log\NullLogger();
 404                         }
 405                         $p['profiler'] = isset( $p['profiler'] ) ? $p['profiler'] : null;
 406                         if ( !isset( $p['trxProfiler'] ) ) {
 407                                 $p['trxProfiler'] = new TransactionProfiler();
 408                         }
 409                         if ( !isset( $p['errorLogger'] ) ) {
 410                                 $p['errorLogger'] = function ( Exception $e ) {
 411                                         trigger_error( get_class( $e ) . ': ' . $e->getMessage(), E_USER_WARNING );
 412                                 };
 413                         }
 414
 415                         $conn = new $class( $p );
 416                 } else {
 417                         $conn = null;
 418                 }
 419
 420                 return $conn;
 421         }
 422
 423         /**
 424          * Set the PSR-3 logger interface to use for query logging. (The logger
 425          * interfaces for connection logging and error logging can be set with the
 426          * constructor.)
 427          *
 428          * @param LoggerInterface $logger
 429          */
 430         public function setLogger( LoggerInterface $logger ) {
 431                 $this->queryLogger = $logger;
 432         }
 433
 434         public function getServerInfo() {
 435                 return $this->getServerVersion();
 436         }
 437
 438         public function bufferResults( $buffer = null ) {
 439                 $res = !$this->getFlag( self::DBO_NOBUFFER );
 440                 if ( $buffer !== null ) {
 441                         $buffer
 442                                 ? $this->clearFlag( self::DBO_NOBUFFER )
 443                                 : $this->setFlag( self::DBO_NOBUFFER );
 444                 }
 445
 446                 return $res;
 447         }
 448
 449         /**
 450          * Turns on (false) or off (true) the automatic generation and sending
 451          * of a "we're sorry, but there has been a database error" page on
 452          * database errors. Default is on (false). When turned off, the
 453          * code should use lastErrno() and lastError() to handle the
 454          * situation as appropriate.
 455          *
 456          * Do not use this function outside of the Database classes.
 457          *
 458          * @param null|bool $ignoreErrors
 459          * @return bool The previous value of the flag.
 460          */
 461         protected function ignoreErrors( $ignoreErrors = null ) {
 462                 $res = $this->getFlag( self::DBO_IGNORE );
 463                 if ( $ignoreErrors !== null ) {
 464                         $ignoreErrors
 465                                 ? $this->setFlag( self::DBO_IGNORE )
 466                                 : $this->clearFlag( self::DBO_IGNORE );
 467                 }
 468
 469                 return $res;
 470         }
 471
 472         public function trxLevel() {
 473                 return $this->mTrxLevel;
 474         }
 475
 476         public function trxTimestamp() {
 477                 return $this->mTrxLevel ? $this->mTrxTimestamp : null;
 478         }
 479
 480         public function tablePrefix( $prefix = null ) {
 481                 $old = $this->mTablePrefix;
 482                 if ( $prefix !== null ) {
 483                         $this->mTablePrefix = $prefix;
 484                         $this->currentDomain = ( $this->mDBname != '' )
 485                                 ? new DatabaseDomain( $this->mDBname, null, $this->mTablePrefix )
 486                                 : DatabaseDomain::newUnspecified();
 487                 }
 488
 489                 return $old;
 490         }
 491
 492         public function dbSchema( $schema = null ) {
 493                 $old = $this->mSchema;
 494                 if ( $schema !== null ) {
 495                         $this->mSchema = $schema;
 496                 }
 497
 498                 return $old;
 499         }
 500
 501         public function getLBInfo( $name = null ) {
 502                 if ( is_null( $name ) ) {
 503                         return $this->mLBInfo;
 504                 } else {
 505                         if ( array_key_exists( $name, $this->mLBInfo ) ) {
 506                                 return $this->mLBInfo[$name];
 507                         } else {
 508                                 return null;
 509                         }
 510                 }
 511         }
 512
 513         public function setLBInfo( $name, $value = null ) {
 514                 if ( is_null( $value ) ) {
 515                         $this->mLBInfo = $name;
 516                 } else {
 517                         $this->mLBInfo[$name] = $value;
 518                 }
 519         }
 520
 521         public function setLazyMasterHandle( IDatabase $conn ) {
 522                 $this->lazyMasterHandle = $conn;
 523         }
 524
 525         /**
 526          * @return IDatabase|null
 527          * @see setLazyMasterHandle()
 528          * @since 1.27
 529          */
 530         protected function getLazyMasterHandle() {
 531                 return $this->lazyMasterHandle;
 532         }
 533
 534         public function implicitGroupby() {
 535                 return true;
 536         }
 537
 538         public function implicitOrderby() {
 539                 return true;
 540         }
 541
 542         public function lastQuery() {
 543                 return $this->mLastQuery;
 544         }
 545
 546         public function doneWrites() {
 547                 return (bool)$this->mLastWriteTime;
 548         }
 549
 550         public function lastDoneWrites() {
 551                 return $this->mLastWriteTime ?: false;
 552         }
 553
 554         public function writesPending() {
 555                 return $this->mTrxLevel && $this->mTrxDoneWrites;
 556         }
 557
 558         public function writesOrCallbacksPending() {
 559                 return $this->mTrxLevel && (
 560                         $this->mTrxDoneWrites || $this->mTrxIdleCallbacks || $this->mTrxPreCommitCallbacks
 561                 );
 562         }
 563
 564         public function pendingWriteQueryDuration( $type = self::ESTIMATE_TOTAL ) {
 565                 if ( !$this->mTrxLevel ) {
 566                         return false;
 567                 } elseif ( !$this->mTrxDoneWrites ) {
 568                         return 0.0;
 569                 }
 570
 571                 switch ( $type ) {
 572                         case self::ESTIMATE_DB_APPLY:
 573                                 $this->ping( $rtt );
 574                                 $rttAdjTotal = $this->mTrxWriteAdjQueryCount * $rtt;
 575                                 $applyTime = max( $this->mTrxWriteAdjDuration - $rttAdjTotal, 0 );
 576                                 // For omitted queries, make them count as something at least
 577                                 $omitted = $this->mTrxWriteQueryCount - $this->mTrxWriteAdjQueryCount;
 578                                 $applyTime += self::TINY_WRITE_SEC * $omitted;
 579
 580                                 return $applyTime;
 581                         default: // everything
 582                                 return $this->mTrxWriteDuration;
 583                 }
 584         }
 585
 586         public function pendingWriteCallers() {
 587                 return $this->mTrxLevel ? $this->mTrxWriteCallers : [];
 588         }
 589
 590         public function pendingWriteRowsAffected() {
 591                 return $this->mTrxWriteAffectedRows;
 592         }
 593
 594         /**
 595          * Get the list of method names that have pending write queries or callbacks
 596          * for this transaction
 597          *
 598          * @return array
 599          */
 600         protected function pendingWriteAndCallbackCallers() {
 601                 if ( !$this->mTrxLevel ) {
 602                         return [];
 603                 }
 604
 605                 $fnames = $this->mTrxWriteCallers;
 606                 foreach ( [
 607                         $this->mTrxIdleCallbacks,
 608                         $this->mTrxPreCommitCallbacks,
 609                         $this->mTrxEndCallbacks
 610                 ] as $callbacks ) {
 611                         foreach ( $callbacks as $callback ) {
 612                                 $fnames[] = $callback[1];
 613                         }
 614                 }
 615
 616                 return $fnames;
 617         }
 618
 619         public function isOpen() {
 620                 return $this->mOpened;
 621         }
 622
 623         public function setFlag( $flag, $remember = self::REMEMBER_NOTHING ) {
 624                 if ( $remember === self::REMEMBER_PRIOR ) {
 625                         array_push( $this->priorFlags, $this->mFlags );
 626                 }
 627                 $this->mFlags |= $flag;
 628         }
 629
 630         public function clearFlag( $flag, $remember = self::REMEMBER_NOTHING ) {
 631                 if ( $remember === self::REMEMBER_PRIOR ) {
 632                         array_push( $this->priorFlags, $this->mFlags );
 633                 }
 634                 $this->mFlags &= ~$flag;
 635         }
 636
 637         public function restoreFlags( $state = self::RESTORE_PRIOR ) {
 638                 if ( !$this->priorFlags ) {
 639                         return;
 640                 }
 641
 642                 if ( $state === self::RESTORE_INITIAL ) {
 643                         $this->mFlags = reset( $this->priorFlags );
 644                         $this->priorFlags = [];
 645                 } else {
 646                         $this->mFlags = array_pop( $this->priorFlags );
 647                 }
 648         }
 649
 650         public function getFlag( $flag ) {
 651                 return !!( $this->mFlags & $flag );
 652         }
 653
 654         /**
 655          * @param string $name Class field name
 656          * @return mixed
 657          * @deprecated Since 1.28
 658          */
 659         public function getProperty( $name ) {
 660                 return $this->$name;
 661         }
 662
 663         public function getDomainID() {
 664                 return $this->currentDomain->getId();
 665         }
 666
 667         final public function getWikiID() {
 668                 return $this->getDomainID();
 669         }
 670
 671         /**
 672          * Get information about an index into an object
 673          * @param string $table Table name
 674          * @param string $index Index name
 675          * @param string $fname Calling function name
 676          * @return mixed Database-specific index description class or false if the index does not exist
 677          */
 678         abstract function indexInfo( $table, $index, $fname = __METHOD__ );
 679
 680         /**
 681          * Wrapper for addslashes()
 682          *
 683          * @param string $s String to be slashed.
 684          * @return string Slashed string.
 685          */
 686         abstract function strencode( $s );
 687
 688         /**
 689          * Set a custom error handler for logging errors during database connection
 690          */
 691         protected function installErrorHandler() {
 692                 $this->mPHPError = false;
 693                 $this->htmlErrors = ini_set( 'html_errors', '0' );
 694                 set_error_handler( [ $this, 'connectionErrorLogger' ] );
 695         }
 696
 697         /**
 698          * Restore the previous error handler and return the last PHP error for this DB
 699          *
 700          * @return bool|string
 701          */
 702         protected function restoreErrorHandler() {
 703                 restore_error_handler();
 704                 if ( $this->htmlErrors !== false ) {
 705                         ini_set( 'html_errors', $this->htmlErrors );
 706                 }
 707
 708                 return $this->getLastPHPError();
 709         }
 710
 711         /**
 712          * @return string|bool Last PHP error for this DB (typically connection errors)
 713          */
 714         protected function getLastPHPError() {
 715                 if ( $this->mPHPError ) {
 716                         $error = preg_replace( '!\[<a.*</a>\]!', '', $this->mPHPError );
 717                         $error = preg_replace( '!^.*?:\s?(.*)$!', '$1', $error );
 718
 719                         return $error;
 720                 }
 721
 722                 return false;
 723         }
 724
 725         /**
 726          * Error handler for logging errors during database connection
 727          * This method should not be used outside of Database classes
 728          *
 729          * @param int $errno
 730          * @param string $errstr
 731          */
 732         public function connectionErrorLogger( $errno, $errstr ) {
 733                 $this->mPHPError = $errstr;
 734         }
 735
 736         /**
 737          * Create a log context to pass to PSR-3 logger functions.
 738          *
 739          * @param array $extras Additional data to add to context
 740          * @return array
 741          */
 742         protected function getLogContext( array $extras = [] ) {
 743                 return array_merge(
 744                         [
 745                                 'db_server' => $this->mServer,
 746                                 'db_name' => $this->mDBname,
 747                                 'db_user' => $this->mUser,
 748                         ],
 749                         $extras
 750                 );
 751         }
 752
 753         public function close() {
 754                 if ( $this->mConn ) {
 755                         if ( $this->trxLevel() ) {
 756                                 $this->commit( __METHOD__, self::FLUSHING_INTERNAL );
 757                         }
 758
 759                         $closed = $this->closeConnection();
 760                         $this->mConn = false;
 761                 } elseif (
 762                         $this->mTrxIdleCallbacks ||
 763                         $this->mTrxPreCommitCallbacks ||
 764                         $this->mTrxEndCallbacks
 765                 ) { // sanity
 766                         throw new RuntimeException( "Transaction callbacks still pending." );
 767                 } else {
 768                         $closed = true;
 769                 }
 770                 $this->mOpened = false;
 771
 772                 return $closed;
 773         }
 774
 775         /**
 776          * Make sure isOpen() returns true as a sanity check
 777          *
 778          * @throws DBUnexpectedError
 779          */
 780         protected function assertOpen() {
 781                 if ( !$this->isOpen() ) {
 782                         throw new DBUnexpectedError( $this, "DB connection was already closed." );
 783                 }
 784         }
 785
 786         /**
 787          * Closes underlying database connection
 788          * @since 1.20
 789          * @return bool Whether connection was closed successfully
 790          */
 791         abstract protected function closeConnection();
 792
 793         public function reportConnectionError( $error = 'Unknown error' ) {
 794                 $myError = $this->lastError();
 795                 if ( $myError ) {
 796                         $error = $myError;
 797                 }
 798
 799                 # New method
 800                 throw new DBConnectionError( $this, $error );
 801         }
 802
 803         /**
 804          * The DBMS-dependent part of query()
 805          *
 806          * @param string $sql SQL query.
 807          * @return ResultWrapper|bool Result object to feed to fetchObject,
 808          *   fetchRow, ...; or false on failure
 809          */
 810         abstract protected function doQuery( $sql );
 811
 812         /**
 813          * Determine whether a query writes to the DB.
 814          * Should return true if unsure.
 815          *
 816          * @param string $sql
 817          * @return bool
 818          */
 819         protected function isWriteQuery( $sql ) {
 820                 return !preg_match(
 821                         '/^(?:SELECT|BEGIN|ROLLBACK|COMMIT|SET|SHOW|EXPLAIN|\(SELECT)\b/i', $sql );
 822         }
 823
 824         /**
 825          * @param string $sql
 826          * @return string|null
 827          */
 828         protected function getQueryVerb( $sql ) {
 829                 return preg_match( '/^\s*([a-z]+)/i', $sql, $m ) ? strtoupper( $m[1] ) : null;
 830         }
 831
 832         /**
 833          * Determine whether a SQL statement is sensitive to isolation level.
 834          * A SQL statement is considered transactable if its result could vary
 835          * depending on the transaction isolation level. Operational commands
 836          * such as 'SET' and 'SHOW' are not considered to be transactable.
 837          *
 838          * @param string $sql
 839          * @return bool
 840          */
 841         protected function isTransactableQuery( $sql ) {
 842                 return !in_array(
 843                         $this->getQueryVerb( $sql ),
 844                         [ 'BEGIN', 'COMMIT', 'ROLLBACK', 'SHOW', 'SET', 'CREATE', 'ALTER' ],
 845                         true
 846                 );
 847         }
 848
 849         /**
 850          * @param string $sql A SQL query
 851          * @return bool Whether $sql is SQL for TEMPORARY table operation
 852          */
 853         protected function registerTempTableOperation( $sql ) {
 854                 if ( preg_match(
 855                         '/^CREATE\s+TEMPORARY\s+TABLE\s+(?:IF\s+NOT\s+EXISTS\s+)?[`"\']?(\w+)[`"\']?/i',
 856                         $sql,
 857                         $matches
 858                 ) ) {
 859                         $this->mSessionTempTables[$matches[1]] = 1;
 860
 861                         return true;
 862                 } elseif ( preg_match(
 863                         '/^DROP\s+(?:TEMPORARY\s+)?TABLE\s+(?:IF\s+EXISTS\s+)?[`"\']?(\w+)[`"\']?/i',
 864                         $sql,
 865                         $matches
 866                 ) ) {
 867                         $isTemp = isset( $this->mSessionTempTables[$matches[1]] );
 868                         unset( $this->mSessionTempTables[$matches[1]] );
 869
 870                         return $isTemp;
 871                 } elseif ( preg_match(
 872                         '/^TRUNCATE\s+(?:TEMPORARY\s+)?TABLE\s+(?:IF\s+EXISTS\s+)?[`"\']?(\w+)[`"\']?/i',
 873                         $sql,
 874                         $matches
 875                 ) ) {
 876                         return isset( $this->mSessionTempTables[$matches[1]] );
 877                 } elseif ( preg_match(
 878                         '/^(?:INSERT\s+(?:\w+\s+)?INTO|UPDATE|DELETE\s+FROM)\s+[`"\']?(\w+)[`"\']?/i',
 879                         $sql,
 880                         $matches
 881                 ) ) {
 882                         return isset( $this->mSessionTempTables[$matches[1]] );
 883                 }
 884
 885                 return false;
 886         }
 887
 888         public function query( $sql, $fname = __METHOD__, $tempIgnore = false ) {
 889                 $priorWritesPending = $this->writesOrCallbacksPending();
 890                 $this->mLastQuery = $sql;
 891
 892                 $isWrite = $this->isWriteQuery( $sql );
 893                 if ( $isWrite ) {
 894                         $isNonTempWrite = !$this->registerTempTableOperation( $sql );
 895                 } else {
 896                         $isNonTempWrite = false;
 897                 }
 898
 899                 if ( $isWrite ) {
 900                         # In theory, non-persistent writes are allowed in read-only mode, but due to things
 901                         # like https://bugs.mysql.com/bug.php?id=33669 that might not work anyway...
 902                         $reason = $this->getReadOnlyReason();
 903                         if ( $reason !== false ) {
 904                                 throw new DBReadOnlyError( $this, "Database is read-only: $reason" );
 905                         }
 906                         # Set a flag indicating that writes have been done
 907                         $this->mLastWriteTime = microtime( true );
 908                 }
 909
 910                 # Add trace comment to the begin of the sql string, right after the operator.
 911                 # Or, for one-word queries (like "BEGIN" or COMMIT") add it to the end (T44598)
 912                 $commentedSql = preg_replace( '/\s|$/', " /* $fname {$this->agent} */ ", $sql, 1 );
 913
 914                 # Start implicit transactions that wrap the request if DBO_TRX is enabled
 915                 if ( !$this->mTrxLevel && $this->getFlag( self::DBO_TRX )
 916                         && $this->isTransactableQuery( $sql )
 917                 ) {
 918                         $this->begin( __METHOD__ . " ($fname)", self::TRANSACTION_INTERNAL );
 919                         $this->mTrxAutomatic = true;
 920                 }
 921
 922                 # Keep track of whether the transaction has write queries pending
 923                 if ( $this->mTrxLevel && !$this->mTrxDoneWrites && $isWrite ) {
 924                         $this->mTrxDoneWrites = true;
 925                         $this->trxProfiler->transactionWritingIn(
 926                                 $this->mServer, $this->mDBname, $this->mTrxShortId );
 927                 }
 928
 929                 if ( $this->getFlag( self::DBO_DEBUG ) ) {
 930                         $this->queryLogger->debug( "{$this->mDBname} {$commentedSql}" );
 931                 }
 932
 933                 # Avoid fatals if close() was called
 934                 $this->assertOpen();
 935
 936                 # Send the query to the server
 937                 $ret = $this->doProfiledQuery( $sql, $commentedSql, $isNonTempWrite, $fname );
 938
 939                 # Try reconnecting if the connection was lost
 940                 if ( false === $ret && $this->wasErrorReissuable() ) {
 941                         $recoverable = $this->canRecoverFromDisconnect( $sql, $priorWritesPending );
 942                         # Stash the last error values before anything might clear them
 943                         $lastError = $this->lastError();
 944                         $lastErrno = $this->lastErrno();
 945                         # Update state tracking to reflect transaction loss due to disconnection
 946                         $this->handleSessionLoss();
 947                         if ( $this->reconnect() ) {
 948                                 $msg = __METHOD__ . ': lost connection to {dbserver}; reconnected';
 949                                 $params = [ 'dbserver' => $this->getServer() ];
 950                                 $this->connLogger->warning( $msg, $params );
 951                                 $this->queryLogger->warning(
 952                                         "$msg:\n" . ( new RuntimeException() )->getTraceAsString(),
 953                                         $params );
 954
 955                                 if ( !$recoverable ) {
 956                                         # Callers may catch the exception and continue to use the DB
 957                                         $this->reportQueryError( $lastError, $lastErrno, $sql, $fname );
 958                                 } else {
 959                                         # Should be safe to silently retry the query
 960                                         $ret = $this->doProfiledQuery( $sql, $commentedSql, $isNonTempWrite, $fname );
 961                                 }
 962                         } else {
 963                                 $msg = __METHOD__ . ': lost connection to {dbserver} permanently';
 964                                 $this->connLogger->error( $msg, [ 'dbserver' => $this->getServer() ] );
 965                         }
 966                 }
 967
 968                 if ( false === $ret ) {
 969                         # Deadlocks cause the entire transaction to abort, not just the statement.
 970                         # https://dev.mysql.com/doc/refman/5.7/en/innodb-error-handling.html
 971                         # https://www.postgresql.org/docs/9.1/static/explicit-locking.html
 972                         if ( $this->wasDeadlock() ) {
 973                                 if ( $this->explicitTrxActive() || $priorWritesPending ) {
 974                                         $tempIgnore = false; // not recoverable
 975                                 }
 976                                 # Update state tracking to reflect transaction loss
 977                                 $this->handleSessionLoss();
 978                         }
 979
 980                         $this->reportQueryError(
 981                                 $this->lastError(), $this->lastErrno(), $sql, $fname, $tempIgnore );
 982                 }
 983
 984                 $res = $this->resultObject( $ret );
 985
 986                 return $res;
 987         }
 988
 989         /**
 990          * Helper method for query() that handles profiling and logging and sends
 991          * the query to doQuery()
 992          *
 993          * @param string $sql Original SQL query
 994          * @param string $commentedSql SQL query with debugging/trace comment
 995          * @param bool $isWrite Whether the query is a (non-temporary) write operation
 996          * @param string $fname Name of the calling function
 997          * @return bool|ResultWrapper True for a successful write query, ResultWrapper
 998          *     object for a successful read query, or false on failure
 999          */
1000         private function doProfiledQuery( $sql, $commentedSql, $isWrite, $fname ) {
1001                 $isMaster = !is_null( $this->getLBInfo( 'master' ) );
1002                 # generalizeSQL() will probably cut down the query to reasonable
1003                 # logging size most of the time. The substr is really just a sanity check.
1004                 if ( $isMaster ) {
1005                         $queryProf = 'query-m: ' . substr( self::generalizeSQL( $sql ), 0, 255 );
1006                 } else {
1007                         $queryProf = 'query: ' . substr( self::generalizeSQL( $sql ), 0, 255 );
1008                 }
1009
1010                 # Include query transaction state
1011                 $queryProf .= $this->mTrxShortId ? " [TRX#{$this->mTrxShortId}]" : "";
1012
1013                 $startTime = microtime( true );
1014                 if ( $this->profiler ) {
1015                         call_user_func( [ $this->profiler, 'profileIn' ], $queryProf );
1016                 }
1017                 $ret = $this->doQuery( $commentedSql );
1018                 if ( $this->profiler ) {
1019                         call_user_func( [ $this->profiler, 'profileOut' ], $queryProf );
1020                 }
1021                 $queryRuntime = max( microtime( true ) - $startTime, 0.0 );
1022
1023                 unset( $queryProfSection ); // profile out (if set)
1024
1025                 if ( $ret !== false ) {
1026                         $this->lastPing = $startTime;
1027                         if ( $isWrite && $this->mTrxLevel ) {
1028                                 $this->updateTrxWriteQueryTime( $sql, $queryRuntime, $this->affectedRows() );
1029                                 $this->mTrxWriteCallers[] = $fname;
1030                         }
1031                 }
1032
1033                 if ( $sql === self::PING_QUERY ) {
1034                         $this->mRTTEstimate = $queryRuntime;
1035                 }
1036
1037                 $this->trxProfiler->recordQueryCompletion(
1038                         $queryProf, $startTime, $isWrite, $this->affectedRows()
1039                 );
1040                 $this->queryLogger->debug( $sql, [
1041                         'method' => $fname,
1042                         'master' => $isMaster,
1043                         'runtime' => $queryRuntime,
1044                 ] );
1045
1046                 return $ret;
1047         }
1048
1049         /**
1050          * Update the estimated run-time of a query, not counting large row lock times
1051          *
1052          * LoadBalancer can be set to rollback transactions that will create huge replication
1053          * lag. It bases this estimate off of pendingWriteQueryDuration(). Certain simple
1054          * queries, like inserting a row can take a long time due to row locking. This method
1055          * uses some simple heuristics to discount those cases.
1056          *
1057          * @param string $sql A SQL write query
1058          * @param float $runtime Total runtime, including RTT
1059          * @param int $affected Affected row count
1060          */
1061         private function updateTrxWriteQueryTime( $sql, $runtime, $affected ) {
1062                 // Whether this is indicative of replica DB runtime (except for RBR or ws_repl)
1063                 $indicativeOfReplicaRuntime = true;
1064                 if ( $runtime > self::SLOW_WRITE_SEC ) {
1065                         $verb = $this->getQueryVerb( $sql );
1066                         // insert(), upsert(), replace() are fast unless bulky in size or blocked on locks
1067                         if ( $verb === 'INSERT' ) {
1068                                 $indicativeOfReplicaRuntime = $this->affectedRows() > self::SMALL_WRITE_ROWS;
1069                         } elseif ( $verb === 'REPLACE' ) {
1070                                 $indicativeOfReplicaRuntime = $this->affectedRows() > self::SMALL_WRITE_ROWS / 2;
1071                         }
1072                 }
1073
1074                 $this->mTrxWriteDuration += $runtime;
1075                 $this->mTrxWriteQueryCount += 1;
1076                 $this->mTrxWriteAffectedRows += $affected;
1077                 if ( $indicativeOfReplicaRuntime ) {
1078                         $this->mTrxWriteAdjDuration += $runtime;
1079                         $this->mTrxWriteAdjQueryCount += 1;
1080                 }
1081         }
1082
1083         /**
1084          * Determine whether or not it is safe to retry queries after a database
1085          * connection is lost
1086          *
1087          * @param string $sql SQL query
1088          * @param bool $priorWritesPending Whether there is a transaction open with
1089          *     possible write queries or transaction pre-commit/idle callbacks
1090          *     waiting on it to finish.
1091          * @return bool True if it is safe to retry the query, false otherwise
1092          */
1093         private function canRecoverFromDisconnect( $sql, $priorWritesPending ) {
1094                 # Transaction dropped; this can mean lost writes, or REPEATABLE-READ snapshots.
1095                 # Dropped connections also mean that named locks are automatically released.
1096                 # Only allow error suppression in autocommit mode or when the lost transaction
1097                 # didn't matter anyway (aside from DBO_TRX snapshot loss).
1098                 if ( $this->mNamedLocksHeld ) {
1099                         return false; // possible critical section violation
1100                 } elseif ( $sql === 'COMMIT' ) {
1101                         return !$priorWritesPending; // nothing written anyway? (T127428)
1102                 } elseif ( $sql === 'ROLLBACK' ) {
1103                         return true; // transaction lost...which is also what was requested :)
1104                 } elseif ( $this->explicitTrxActive() ) {
1105                         return false; // don't drop atomocity
1106                 } elseif ( $priorWritesPending ) {
1107                         return false; // prior writes lost from implicit transaction
1108                 }
1109
1110                 return true;
1111         }
1112
1113         /**
1114          * Clean things up after transaction loss due to disconnection
1115          *
1116          * @return null|Exception
1117          */
1118         private function handleSessionLoss() {
1119                 $this->mTrxLevel = 0;
1120                 $this->mTrxIdleCallbacks = []; // T67263
1121                 $this->mTrxPreCommitCallbacks = []; // T67263
1122                 $this->mSessionTempTables = [];
1123                 $this->mNamedLocksHeld = [];
1124                 try {
1125                         // Handle callbacks in mTrxEndCallbacks
1126                         $this->runOnTransactionIdleCallbacks( self::TRIGGER_ROLLBACK );
1127                         $this->runTransactionListenerCallbacks( self::TRIGGER_ROLLBACK );
1128                         return null;
1129                 } catch ( Exception $e ) {
1130                         // Already logged; move on...
1131                         return $e;
1132                 }
1133         }
1134
1135         /**
1136          * Checks whether the cause of the error is detected to be a timeout.
1137          *
1138          * It returns false by default, and not all engines support detecting this yet.
1139          * If this returns false, it will be treated as a generic query error.
1140          *
1141          * @param string $error Error text
1142          * @param int $errno Error number
1143          * @return bool
1144          */
1145         protected function wasQueryTimeout( $error, $errno ) {
1146                 return false;
1147         }
1148
1149         public function reportQueryError( $error, $errno, $sql, $fname, $tempIgnore = false ) {
1150                 if ( $this->ignoreErrors() || $tempIgnore ) {
1151                         $this->queryLogger->debug( "SQL ERROR (ignored): $error\n" );
1152                 } else {
1153                         $sql1line = mb_substr( str_replace( "\n", "\\n", $sql ), 0, 5 * 1024 );
1154                         $this->queryLogger->error(
1155                                 "{fname}\t{db_server}\t{errno}\t{error}\t{sql1line}",
1156                                 $this->getLogContext( [
1157                                         'method' => __METHOD__,
1158                                         'errno' => $errno,
1159                                         'error' => $error,
1160                                         'sql1line' => $sql1line,
1161                                         'fname' => $fname,
1162                                 ] )
1163                         );
1164                         $this->queryLogger->debug( "SQL ERROR: " . $error . "\n" );
1165                         $wasQueryTimeout = $this->wasQueryTimeout( $error, $errno );
1166                         if ( $wasQueryTimeout ) {
1167                                 throw new DBQueryTimeoutError( $this, $error, $errno, $sql, $fname );
1168                         } else {
1169                                 throw new DBQueryError( $this, $error, $errno, $sql, $fname );
1170                         }
1171                 }
1172         }
1173
1174         public function freeResult( $res ) {
1175         }
1176
1177         public function selectField(
1178                 $table, $var, $cond = '', $fname = __METHOD__, $options = [], $join_conds = []
1179         ) {
1180                 if ( $var === '*' ) { // sanity
1181                         throw new DBUnexpectedError( $this, "Cannot use a * field: got '$var'" );
1182                 }
1183
1184                 if ( !is_array( $options ) ) {
1185                         $options = [ $options ];
1186                 }
1187
1188                 $options['LIMIT'] = 1;
1189
1190                 $res = $this->select( $table, $var, $cond, $fname, $options, $join_conds );
1191                 if ( $res === false || !$this->numRows( $res ) ) {
1192                         return false;
1193                 }
1194
1195                 $row = $this->fetchRow( $res );
1196
1197                 if ( $row !== false ) {
1198                         return reset( $row );
1199                 } else {
1200                         return false;
1201                 }
1202         }
1203
1204         public function selectFieldValues(
1205                 $table, $var, $cond = '', $fname = __METHOD__, $options = [], $join_conds = []
1206         ) {
1207                 if ( $var === '*' ) { // sanity
1208                         throw new DBUnexpectedError( $this, "Cannot use a * field" );
1209                 } elseif ( !is_string( $var ) ) { // sanity
1210                         throw new DBUnexpectedError( $this, "Cannot use an array of fields" );
1211                 }
1212
1213                 if ( !is_array( $options ) ) {
1214                         $options = [ $options ];
1215                 }
1216
1217                 $res = $this->select( $table, $var, $cond, $fname, $options, $join_conds );
1218                 if ( $res === false ) {
1219                         return false;
1220                 }
1221
1222                 $values = [];
1223                 foreach ( $res as $row ) {
1224                         $values[] = $row->$var;
1225                 }
1226
1227                 return $values;
1228         }
1229
1230         /**
1231          * Returns an optional USE INDEX clause to go after the table, and a
1232          * string to go at the end of the query.
1233          *
1234          * @param array $options Associative array of options to be turned into
1235          *   an SQL query, valid keys are listed in the function.
1236          * @return array
1237          * @see Database::select()
1238          */
1239         protected function makeSelectOptions( $options ) {
1240                 $preLimitTail = $postLimitTail = '';
1241                 $startOpts = '';
1242
1243                 $noKeyOptions = [];
1244
1245                 foreach ( $options as $key => $option ) {
1246                         if ( is_numeric( $key ) ) {
1247                                 $noKeyOptions[$option] = true;
1248                         }
1249                 }
1250
1251                 $preLimitTail .= $this->makeGroupByWithHaving( $options );
1252
1253                 $preLimitTail .= $this->makeOrderBy( $options );
1254
1255                 if ( isset( $noKeyOptions['FOR UPDATE'] ) ) {
1256                         $postLimitTail .= ' FOR UPDATE';
1257                 }
1258
1259                 if ( isset( $noKeyOptions['LOCK IN SHARE MODE'] ) ) {
1260                         $postLimitTail .= ' LOCK IN SHARE MODE';
1261                 }
1262
1263                 if ( isset( $noKeyOptions['DISTINCT'] ) || isset( $noKeyOptions['DISTINCTROW'] ) ) {
1264                         $startOpts .= 'DISTINCT';
1265                 }
1266
1267                 # Various MySQL extensions
1268                 if ( isset( $noKeyOptions['STRAIGHT_JOIN'] ) ) {
1269                         $startOpts .= ' /*! STRAIGHT_JOIN */';
1270                 }
1271
1272                 if ( isset( $noKeyOptions['HIGH_PRIORITY'] ) ) {
1273                         $startOpts .= ' HIGH_PRIORITY';
1274                 }
1275
1276                 if ( isset( $noKeyOptions['SQL_BIG_RESULT'] ) ) {
1277                         $startOpts .= ' SQL_BIG_RESULT';
1278                 }
1279
1280                 if ( isset( $noKeyOptions['SQL_BUFFER_RESULT'] ) ) {
1281                         $startOpts .= ' SQL_BUFFER_RESULT';
1282                 }
1283
1284                 if ( isset( $noKeyOptions['SQL_SMALL_RESULT'] ) ) {
1285                         $startOpts .= ' SQL_SMALL_RESULT';
1286                 }
1287
1288                 if ( isset( $noKeyOptions['SQL_CALC_FOUND_ROWS'] ) ) {
1289                         $startOpts .= ' SQL_CALC_FOUND_ROWS';
1290                 }
1291
1292                 if ( isset( $noKeyOptions['SQL_CACHE'] ) ) {
1293                         $startOpts .= ' SQL_CACHE';
1294                 }
1295
1296                 if ( isset( $noKeyOptions['SQL_NO_CACHE'] ) ) {
1297                         $startOpts .= ' SQL_NO_CACHE';
1298                 }
1299
1300                 if ( isset( $options['USE INDEX'] ) && is_string( $options['USE INDEX'] ) ) {
1301                         $useIndex = $this->useIndexClause( $options['USE INDEX'] );
1302                 } else {
1303                         $useIndex = '';
1304                 }
1305                 if ( isset( $options['IGNORE INDEX'] ) && is_string( $options['IGNORE INDEX'] ) ) {
1306                         $ignoreIndex = $this->ignoreIndexClause( $options['IGNORE INDEX'] );
1307                 } else {
1308                         $ignoreIndex = '';
1309                 }
1310
1311                 return [ $startOpts, $useIndex, $preLimitTail, $postLimitTail, $ignoreIndex ];
1312         }
1313
1314         /**
1315          * Returns an optional GROUP BY with an optional HAVING
1316          *
1317          * @param array $options Associative array of options
1318          * @return string
1319          * @see Database::select()
1320          * @since 1.21
1321          */
1322         protected function makeGroupByWithHaving( $options ) {
1323                 $sql = '';
1324                 if ( isset( $options['GROUP BY'] ) ) {
1325                         $gb = is_array( $options['GROUP BY'] )
1326                                 ? implode( ',', $options['GROUP BY'] )
1327                                 : $options['GROUP BY'];
1328                         $sql .= ' GROUP BY ' . $gb;
1329                 }
1330                 if ( isset( $options['HAVING'] ) ) {
1331                         $having = is_array( $options['HAVING'] )
1332                                 ? $this->makeList( $options['HAVING'], self::LIST_AND )
1333                                 : $options['HAVING'];
1334                         $sql .= ' HAVING ' . $having;
1335                 }
1336
1337                 return $sql;
1338         }
1339
1340         /**
1341          * Returns an optional ORDER BY
1342          *
1343          * @param array $options Associative array of options
1344          * @return string
1345          * @see Database::select()
1346          * @since 1.21
1347          */
1348         protected function makeOrderBy( $options ) {
1349                 if ( isset( $options['ORDER BY'] ) ) {
1350                         $ob = is_array( $options['ORDER BY'] )
1351                                 ? implode( ',', $options['ORDER BY'] )
1352                                 : $options['ORDER BY'];
1353
1354                         return ' ORDER BY ' . $ob;
1355                 }
1356
1357                 return '';
1358         }
1359
1360         public function select( $table, $vars, $conds = '', $fname = __METHOD__,
1361                 $options = [], $join_conds = [] ) {
1362                 $sql = $this->selectSQLText( $table, $vars, $conds, $fname, $options, $join_conds );
1363
1364                 return $this->query( $sql, $fname );
1365         }
1366
1367         public function selectSQLText( $table, $vars, $conds = '', $fname = __METHOD__,
1368                 $options = [], $join_conds = []
1369         ) {
1370                 if ( is_array( $vars ) ) {
1371                         $vars = implode( ',', $this->fieldNamesWithAlias( $vars ) );
1372                 }
1373
1374                 $options = (array)$options;
1375                 $useIndexes = ( isset( $options['USE INDEX'] ) && is_array( $options['USE INDEX'] ) )
1376                         ? $options['USE INDEX']
1377                         : [];
1378                 $ignoreIndexes = (
1379                         isset( $options['IGNORE INDEX'] ) &&
1380                         is_array( $options['IGNORE INDEX'] )
1381                 )
1382                         ? $options['IGNORE INDEX']
1383                         : [];
1384
1385                 if ( is_array( $table ) ) {
1386                         $from = ' FROM ' .
1387                                 $this->tableNamesWithIndexClauseOrJOIN(
1388                                         $table, $useIndexes, $ignoreIndexes, $join_conds );
1389                 } elseif ( $table != '' ) {
1390                         if ( $table[0] == ' ' ) {
1391                                 $from = ' FROM ' . $table;
1392                         } else {
1393                                 $from = ' FROM ' .
1394                                         $this->tableNamesWithIndexClauseOrJOIN(
1395                                                 [ $table ], $useIndexes, $ignoreIndexes, [] );
1396                         }
1397                 } else {
1398                         $from = '';
1399                 }
1400
1401                 list( $startOpts, $useIndex, $preLimitTail, $postLimitTail, $ignoreIndex ) =
1402                         $this->makeSelectOptions( $options );
1403
1404                 if ( !empty( $conds ) ) {
1405                         if ( is_array( $conds ) ) {
1406                                 $conds = $this->makeList( $conds, self::LIST_AND );
1407                         }
1408                         $sql = "SELECT $startOpts $vars $from $useIndex $ignoreIndex " .
1409                                 "WHERE $conds $preLimitTail";
1410                 } else {
1411                         $sql = "SELECT $startOpts $vars $from $useIndex $ignoreIndex $preLimitTail";
1412                 }
1413
1414                 if ( isset( $options['LIMIT'] ) ) {
1415                         $sql = $this->limitResult( $sql, $options['LIMIT'],
1416                                 isset( $options['OFFSET'] ) ? $options['OFFSET'] : false );
1417                 }
1418                 $sql = "$sql $postLimitTail";
1419
1420                 if ( isset( $options['EXPLAIN'] ) ) {
1421                         $sql = 'EXPLAIN ' . $sql;
1422                 }
1423
1424                 return $sql;
1425         }
1426
1427         public function selectRow( $table, $vars, $conds, $fname = __METHOD__,
1428                 $options = [], $join_conds = []
1429         ) {
1430                 $options = (array)$options;
1431                 $options['LIMIT'] = 1;
1432                 $res = $this->select( $table, $vars, $conds, $fname, $options, $join_conds );
1433
1434                 if ( $res === false ) {
1435                         return false;
1436                 }
1437
1438                 if ( !$this->numRows( $res ) ) {
1439                         return false;
1440                 }
1441
1442                 $obj = $this->fetchObject( $res );
1443
1444                 return $obj;
1445         }
1446
1447         public function estimateRowCount(
1448                 $table, $vars = '*', $conds = '', $fname = __METHOD__, $options = []
1449         ) {
1450                 $rows = 0;
1451                 $res = $this->select( $table, [ 'rowcount' => 'COUNT(*)' ], $conds, $fname, $options );
1452
1453                 if ( $res ) {
1454                         $row = $this->fetchRow( $res );
1455                         $rows = ( isset( $row['rowcount'] ) ) ? (int)$row['rowcount'] : 0;
1456                 }
1457
1458                 return $rows;
1459         }
1460
1461         public function selectRowCount(
1462                 $tables, $vars = '*', $conds = '', $fname = __METHOD__, $options = [], $join_conds = []
1463         ) {
1464                 $rows = 0;
1465                 $sql = $this->selectSQLText( $tables, '1', $conds, $fname, $options, $join_conds );
1466                 // The identifier quotes is primarily for MSSQL.
1467                 $rowCountCol = $this->addIdentifierQuotes( "rowcount" );
1468                 $tableName = $this->addIdentifierQuotes( "tmp_count" );
1469                 $res = $this->query( "SELECT COUNT(*) AS $rowCountCol FROM ($sql) $tableName", $fname );
1470
1471                 if ( $res ) {
1472                         $row = $this->fetchRow( $res );
1473                         $rows = ( isset( $row['rowcount'] ) ) ? (int)$row['rowcount'] : 0;
1474                 }
1475
1476                 return $rows;
1477         }
1478
1479         /**
1480          * Removes most variables from an SQL query and replaces them with X or N for numbers.
1481          * It's only slightly flawed. Don't use for anything important.
1482          *
1483          * @param string $sql A SQL Query
1484          *
1485          * @return string
1486          */
1487         protected static function generalizeSQL( $sql ) {
1488                 # This does the same as the regexp below would do, but in such a way
1489                 # as to avoid crashing php on some large strings.
1490                 # $sql = preg_replace( "/'([^\\\\']|\\\\.)*'|\"([^\\\\\"]|\\\\.)*\"/", "'X'", $sql );
1491
1492                 $sql = str_replace( "\\\\", '', $sql );
1493                 $sql = str_replace( "\\'", '', $sql );
1494                 $sql = str_replace( "\\\"", '', $sql );
1495                 $sql = preg_replace( "/'.*'/s", "'X'", $sql );
1496                 $sql = preg_replace( '/".*"/s', "'X'", $sql );
1497
1498                 # All newlines, tabs, etc replaced by single space
1499                 $sql = preg_replace( '/\s+/', ' ', $sql );
1500
1501                 # All numbers => N,
1502                 # except the ones surrounded by characters, e.g. l10n
1503                 $sql = preg_replace( '/-?\d+(,-?\d+)+/s', 'N,...,N', $sql );
1504                 $sql = preg_replace( '/(?<![a-zA-Z])-?\d+(?![a-zA-Z])/s', 'N', $sql );
1505
1506                 return $sql;
1507         }
1508
1509         public function fieldExists( $table, $field, $fname = __METHOD__ ) {
1510                 $info = $this->fieldInfo( $table, $field );
1511
1512                 return (bool)$info;
1513         }
1514
1515         public function indexExists( $table, $index, $fname = __METHOD__ ) {
1516                 if ( !$this->tableExists( $table ) ) {
1517                         return null;
1518                 }
1519
1520                 $info = $this->indexInfo( $table, $index, $fname );
1521                 if ( is_null( $info ) ) {
1522                         return null;
1523                 } else {
1524                         return $info !== false;
1525                 }
1526         }
1527
1528         public function tableExists( $table, $fname = __METHOD__ ) {
1529                 $tableRaw = $this->tableName( $table, 'raw' );
1530                 if ( isset( $this->mSessionTempTables[$tableRaw] ) ) {
1531                         return true; // already known to exist
1532                 }
1533
1534                 $table = $this->tableName( $table );
1535                 $ignoreErrors = true;
1536                 $res = $this->query( "SELECT 1 FROM $table LIMIT 1", $fname, $ignoreErrors );
1537
1538                 return (bool)$res;
1539         }
1540
1541         public function indexUnique( $table, $index ) {
1542                 $indexInfo = $this->indexInfo( $table, $index );
1543
1544                 if ( !$indexInfo ) {
1545                         return null;
1546                 }
1547
1548                 return !$indexInfo[0]->Non_unique;
1549         }
1550
1551         /**
1552          * Helper for Database::insert().
1553          *
1554          * @param array $options
1555          * @return string
1556          */
1557         protected function makeInsertOptions( $options ) {
1558                 return implode( ' ', $options );
1559         }
1560
1561         public function insert( $table, $a, $fname = __METHOD__, $options = [] ) {
1562                 # No rows to insert, easy just return now
1563                 if ( !count( $a ) ) {
1564                         return true;
1565                 }
1566
1567                 $table = $this->tableName( $table );
1568
1569                 if ( !is_array( $options ) ) {
1570                         $options = [ $options ];
1571                 }
1572
1573                 $fh = null;
1574                 if ( isset( $options['fileHandle'] ) ) {
1575                         $fh = $options['fileHandle'];
1576                 }
1577                 $options = $this->makeInsertOptions( $options );
1578
1579                 if ( isset( $a[0] ) && is_array( $a[0] ) ) {
1580                         $multi = true;
1581                         $keys = array_keys( $a[0] );
1582                 } else {
1583                         $multi = false;
1584                         $keys = array_keys( $a );
1585                 }
1586
1587                 $sql = 'INSERT ' . $options .
1588                         " INTO $table (" . implode( ',', $keys ) . ') VALUES ';
1589
1590                 if ( $multi ) {
1591                         $first = true;
1592                         foreach ( $a as $row ) {
1593                                 if ( $first ) {
1594                                         $first = false;
1595                                 } else {
1596                                         $sql .= ',';
1597                                 }
1598                                 $sql .= '(' . $this->makeList( $row ) . ')';
1599                         }
1600                 } else {
1601                         $sql .= '(' . $this->makeList( $a ) . ')';
1602                 }
1603
1604                 if ( $fh !== null && false === fwrite( $fh, $sql ) ) {
1605                         return false;
1606                 } elseif ( $fh !== null ) {
1607                         return true;
1608                 }
1609
1610                 return (bool)$this->query( $sql, $fname );
1611         }
1612
1613         /**
1614          * Make UPDATE options array for Database::makeUpdateOptions
1615          *
1616          * @param array $options
1617          * @return array
1618          */
1619         protected function makeUpdateOptionsArray( $options ) {
1620                 if ( !is_array( $options ) ) {
1621                         $options = [ $options ];
1622                 }
1623
1624                 $opts = [];
1625
1626                 if ( in_array( 'IGNORE', $options ) ) {
1627                         $opts[] = 'IGNORE';
1628                 }
1629
1630                 return $opts;
1631         }
1632
1633         /**
1634          * Make UPDATE options for the Database::update function
1635          *
1636          * @param array $options The options passed to Database::update
1637          * @return string
1638          */
1639         protected function makeUpdateOptions( $options ) {
1640                 $opts = $this->makeUpdateOptionsArray( $options );
1641
1642                 return implode( ' ', $opts );
1643         }
1644
1645         public function update( $table, $values, $conds, $fname = __METHOD__, $options = [] ) {
1646                 $table = $this->tableName( $table );
1647                 $opts = $this->makeUpdateOptions( $options );
1648                 $sql = "UPDATE $opts $table SET " . $this->makeList( $values, self::LIST_SET );
1649
1650                 if ( $conds !== [] && $conds !== '*' ) {
1651                         $sql .= " WHERE " . $this->makeList( $conds, self::LIST_AND );
1652                 }
1653
1654                 return (bool)$this->query( $sql, $fname );
1655         }
1656
1657         public function makeList( $a, $mode = self::LIST_COMMA ) {
1658                 if ( !is_array( $a ) ) {
1659                         throw new DBUnexpectedError( $this, __METHOD__ . ' called with incorrect parameters' );
1660                 }
1661
1662                 $first = true;
1663                 $list = '';
1664
1665                 foreach ( $a as $field => $value ) {
1666                         if ( !$first ) {
1667                                 if ( $mode == self::LIST_AND ) {
1668                                         $list .= ' AND ';
1669                                 } elseif ( $mode == self::LIST_OR ) {
1670                                         $list .= ' OR ';
1671                                 } else {
1672                                         $list .= ',';
1673                                 }
1674                         } else {
1675                                 $first = false;
1676                         }
1677
1678                         if ( ( $mode == self::LIST_AND || $mode == self::LIST_OR ) && is_numeric( $field ) ) {
1679                                 $list .= "($value)";
1680                         } elseif ( $mode == self::LIST_SET && is_numeric( $field ) ) {
1681                                 $list .= "$value";
1682                         } elseif (
1683                                 ( $mode == self::LIST_AND || $mode == self::LIST_OR ) && is_array( $value )
1684                         ) {
1685                                 // Remove null from array to be handled separately if found
1686                                 $includeNull = false;
1687                                 foreach ( array_keys( $value, null, true ) as $nullKey ) {
1688                                         $includeNull = true;
1689                                         unset( $value[$nullKey] );
1690                                 }
1691                                 if ( count( $value ) == 0 && !$includeNull ) {
1692                                         throw new InvalidArgumentException(
1693                                                 __METHOD__ . ": empty input for field $field" );
1694                                 } elseif ( count( $value ) == 0 ) {
1695                                         // only check if $field is null
1696                                         $list .= "$field IS NULL";
1697                                 } else {
1698                                         // IN clause contains at least one valid element
1699                                         if ( $includeNull ) {
1700                                                 // Group subconditions to ensure correct precedence
1701                                                 $list .= '(';
1702                                         }
1703                                         if ( count( $value ) == 1 ) {
1704                                                 // Special-case single values, as IN isn't terribly efficient
1705                                                 // Don't necessarily assume the single key is 0; we don't
1706                                                 // enforce linear numeric ordering on other arrays here.
1707                                                 $value = array_values( $value )[0];
1708                                                 $list .= $field . " = " . $this->addQuotes( $value );
1709                                         } else {
1710                                                 $list .= $field . " IN (" . $this->makeList( $value ) . ") ";
1711                                         }
1712                                         // if null present in array, append IS NULL
1713                                         if ( $includeNull ) {
1714                                                 $list .= " OR $field IS NULL)";
1715                                         }
1716                                 }
1717                         } elseif ( $value === null ) {
1718                                 if ( $mode == self::LIST_AND || $mode == self::LIST_OR ) {
1719                                         $list .= "$field IS ";
1720                                 } elseif ( $mode == self::LIST_SET ) {
1721                                         $list .= "$field = ";
1722                                 }
1723                                 $list .= 'NULL';
1724                         } else {
1725                                 if (
1726                                         $mode == self::LIST_AND || $mode == self::LIST_OR || $mode == self::LIST_SET
1727                                 ) {
1728                                         $list .= "$field = ";
1729                                 }
1730                                 $list .= $mode == self::LIST_NAMES ? $value : $this->addQuotes( $value );
1731                         }
1732                 }
1733
1734                 return $list;
1735         }
1736
1737         public function makeWhereFrom2d( $data, $baseKey, $subKey ) {
1738                 $conds = [];
1739
1740                 foreach ( $data as $base => $sub ) {
1741                         if ( count( $sub ) ) {
1742                                 $conds[] = $this->makeList(
1743                                         [ $baseKey => $base, $subKey => array_keys( $sub ) ],
1744                                         self::LIST_AND );
1745                         }
1746                 }
1747
1748                 if ( $conds ) {
1749                         return $this->makeList( $conds, self::LIST_OR );
1750                 } else {
1751                         // Nothing to search for...
1752                         return false;
1753                 }
1754         }
1755
1756         public function aggregateValue( $valuedata, $valuename = 'value' ) {
1757                 return $valuename;
1758         }
1759
1760         public function bitNot( $field ) {
1761                 return "(~$field)";
1762         }
1763
1764         public function bitAnd( $fieldLeft, $fieldRight ) {
1765                 return "($fieldLeft & $fieldRight)";
1766         }
1767
1768         public function bitOr( $fieldLeft, $fieldRight ) {
1769                 return "($fieldLeft | $fieldRight)";
1770         }
1771
1772         public function buildConcat( $stringList ) {
1773                 return 'CONCAT(' . implode( ',', $stringList ) . ')';
1774         }
1775
1776         public function buildGroupConcatField(
1777                 $delim, $table, $field, $conds = '', $join_conds = []
1778         ) {
1779                 $fld = "GROUP_CONCAT($field SEPARATOR " . $this->addQuotes( $delim ) . ')';
1780
1781                 return '(' . $this->selectSQLText( $table, $fld, $conds, null, [], $join_conds ) . ')';
1782         }
1783
1784         public function buildStringCast( $field ) {
1785                 return $field;
1786         }
1787
1788         public function databasesAreIndependent() {
1789                 return false;
1790         }
1791
1792         public function selectDB( $db ) {
1793                 # Stub. Shouldn't cause serious problems if it's not overridden, but
1794                 # if your database engine supports a concept similar to MySQL's
1795                 # databases you may as well.
1796                 $this->mDBname = $db;
1797
1798                 return true;
1799         }
1800
1801         public function getDBname() {
1802                 return $this->mDBname;
1803         }
1804
1805         public function getServer() {
1806                 return $this->mServer;
1807         }
1808
1809         public function tableName( $name, $format = 'quoted' ) {
1810                 # Skip the entire process when we have a string quoted on both ends.
1811                 # Note that we check the end so that we will still quote any use of
1812                 # use of `database`.table. But won't break things if someone wants
1813                 # to query a database table with a dot in the name.
1814                 if ( $this->isQuotedIdentifier( $name ) ) {
1815                         return $name;
1816                 }
1817
1818                 # Lets test for any bits of text that should never show up in a table
1819                 # name. Basically anything like JOIN or ON which are actually part of
1820                 # SQL queries, but may end up inside of the table value to combine
1821                 # sql. Such as how the API is doing.
1822                 # Note that we use a whitespace test rather than a \b test to avoid
1823                 # any remote case where a word like on may be inside of a table name
1824                 # surrounded by symbols which may be considered word breaks.
1825                 if ( preg_match( '/(^|\s)(DISTINCT|JOIN|ON|AS)(\s|$)/i', $name ) !== 0 ) {
1826                         return $name;
1827                 }
1828
1829                 # Split database and table into proper variables.
1830                 list( $database, $schema, $prefix, $table ) = $this->qualifiedTableComponents( $name );
1831
1832                 # Quote $table and apply the prefix if not quoted.
1833                 # $tableName might be empty if this is called from Database::replaceVars()
1834                 $tableName = "{$prefix}{$table}";
1835                 if ( $format === 'quoted'
1836                         && !$this->isQuotedIdentifier( $tableName )
1837                         && $tableName !== ''
1838                 ) {
1839                         $tableName = $this->addIdentifierQuotes( $tableName );
1840                 }
1841
1842                 # Quote $schema and $database and merge them with the table name if needed
1843                 $tableName = $this->prependDatabaseOrSchema( $schema, $tableName, $format );
1844                 $tableName = $this->prependDatabaseOrSchema( $database, $tableName, $format );
1845
1846                 return $tableName;
1847         }
1848
1849         /**
1850          * Get the table components needed for a query given the currently selected database
1851          *
1852          * @param string $name Table name in the form of db.schema.table, db.table, or table
1853          * @return array (DB name or "" for default, schema name, table prefix, table name)
1854          */
1855         protected function qualifiedTableComponents( $name ) {
1856                 # We reverse the explode so that database.table and table both output the correct table.
1857                 $dbDetails = explode( '.', $name, 3 );
1858                 if ( count( $dbDetails ) == 3 ) {
1859                         list( $database, $schema, $table ) = $dbDetails;
1860                         # We don't want any prefix added in this case
1861                         $prefix = '';
1862                 } elseif ( count( $dbDetails ) == 2 ) {
1863                         list( $database, $table ) = $dbDetails;
1864                         # We don't want any prefix added in this case
1865                         $prefix = '';
1866                         # In dbs that support it, $database may actually be the schema
1867                         # but that doesn't affect any of the functionality here
1868                         $schema = '';
1869                 } else {
1870                         list( $table ) = $dbDetails;
1871                         if ( isset( $this->tableAliases[$table] ) ) {
1872                                 $database = $this->tableAliases[$table]['dbname'];
1873                                 $schema = is_string( $this->tableAliases[$table]['schema'] )
1874                                         ? $this->tableAliases[$table]['schema']
1875                                         : $this->mSchema;
1876                                 $prefix = is_string( $this->tableAliases[$table]['prefix'] )
1877                                         ? $this->tableAliases[$table]['prefix']
1878                                         : $this->mTablePrefix;
1879                         } else {
1880                                 $database = '';
1881                                 $schema = $this->mSchema; # Default schema
1882                                 $prefix = $this->mTablePrefix; # Default prefix
1883                         }
1884                 }
1885
1886                 return [ $database, $schema, $prefix, $table ];
1887         }
1888
1889         /**
1890          * @param string|null $namespace Database or schema
1891          * @param string $relation Name of table, view, sequence, etc...
1892          * @param string $format One of (raw, quoted)
1893          * @return string Relation name with quoted and merged $namespace as needed
1894          */
1895         private function prependDatabaseOrSchema( $namespace, $relation, $format ) {
1896                 if ( strlen( $namespace ) ) {
1897                         if ( $format === 'quoted' && !$this->isQuotedIdentifier( $namespace ) ) {
1898                                 $namespace = $this->addIdentifierQuotes( $namespace );
1899                         }
1900                         $relation = $namespace . '.' . $relation;
1901                 }
1902
1903                 return $relation;
1904         }
1905
1906         public function tableNames() {
1907                 $inArray = func_get_args();
1908                 $retVal = [];
1909
1910                 foreach ( $inArray as $name ) {
1911                         $retVal[$name] = $this->tableName( $name );
1912                 }
1913
1914                 return $retVal;
1915         }
1916
1917         public function tableNamesN() {
1918                 $inArray = func_get_args();
1919                 $retVal = [];
1920
1921                 foreach ( $inArray as $name ) {
1922                         $retVal[] = $this->tableName( $name );
1923                 }
1924
1925                 return $retVal;
1926         }
1927
1928         /**
1929          * Get an aliased table name
1930          * e.g. tableName AS newTableName
1931          *
1932          * @param string $name Table name, see tableName()
1933          * @param string|bool $alias Alias (optional)
1934          * @return string SQL name for aliased table. Will not alias a table to its own name
1935          */
1936         protected function tableNameWithAlias( $name, $alias = false ) {
1937                 if ( !$alias || $alias == $name ) {
1938                         return $this->tableName( $name );
1939                 } else {
1940                         return $this->tableName( $name ) . ' ' . $this->addIdentifierQuotes( $alias );
1941                 }
1942         }
1943
1944         /**
1945          * Gets an array of aliased table names
1946          *
1947          * @param array $tables [ [alias] => table ]
1948          * @return string[] See tableNameWithAlias()
1949          */
1950         protected function tableNamesWithAlias( $tables ) {
1951                 $retval = [];
1952                 foreach ( $tables as $alias => $table ) {
1953                         if ( is_numeric( $alias ) ) {
1954                                 $alias = $table;
1955                         }
1956                         $retval[] = $this->tableNameWithAlias( $table, $alias );
1957                 }
1958
1959                 return $retval;
1960         }
1961
1962         /**
1963          * Get an aliased field name
1964          * e.g. fieldName AS newFieldName
1965          *
1966          * @param string $name Field name
1967          * @param string|bool $alias Alias (optional)
1968          * @return string SQL name for aliased field. Will not alias a field to its own name
1969          */
1970         protected function fieldNameWithAlias( $name, $alias = false ) {
1971                 if ( !$alias || (string)$alias === (string)$name ) {
1972                         return $name;
1973                 } else {
1974                         return $name . ' AS ' . $this->addIdentifierQuotes( $alias ); // PostgreSQL needs AS
1975                 }
1976         }
1977
1978         /**
1979          * Gets an array of aliased field names
1980          *
1981          * @param array $fields [ [alias] => field ]
1982          * @return string[] See fieldNameWithAlias()
1983          */
1984         protected function fieldNamesWithAlias( $fields ) {
1985                 $retval = [];
1986                 foreach ( $fields as $alias => $field ) {
1987                         if ( is_numeric( $alias ) ) {
1988                                 $alias = $field;
1989                         }
1990                         $retval[] = $this->fieldNameWithAlias( $field, $alias );
1991                 }
1992
1993                 return $retval;
1994         }
1995
1996         /**
1997          * Get the aliased table name clause for a FROM clause
1998          * which might have a JOIN and/or USE INDEX or IGNORE INDEX clause
1999          *
2000          * @param array $tables ( [alias] => table )
2001          * @param array $use_index Same as for select()
2002          * @param array $ignore_index Same as for select()
2003          * @param array $join_conds Same as for select()
2004          * @return string
2005          */
2006         protected function tableNamesWithIndexClauseOrJOIN(
2007                 $tables, $use_index = [], $ignore_index = [], $join_conds = []
2008         ) {
2009                 $ret = [];
2010                 $retJOIN = [];
2011                 $use_index = (array)$use_index;
2012                 $ignore_index = (array)$ignore_index;
2013                 $join_conds = (array)$join_conds;
2014
2015                 foreach ( $tables as $alias => $table ) {
2016                         if ( !is_string( $alias ) ) {
2017                                 // No alias? Set it equal to the table name
2018                                 $alias = $table;
2019                         }
2020
2021                         if ( is_array( $table ) ) {
2022                                 // A parenthesized group
2023                                 $joinedTable = '('
2024                                         . $this->tableNamesWithIndexClauseOrJOIN( $table, $use_index, $ignore_index, $join_conds )
2025                                         . ')';
2026                         } else {
2027                                 $joinedTable = $this->tableNameWithAlias( $table, $alias );
2028                         }
2029
2030                         // Is there a JOIN clause for this table?
2031                         if ( isset( $join_conds[$alias] ) ) {
2032                                 list( $joinType, $conds ) = $join_conds[$alias];
2033                                 $tableClause = $joinType;
2034                                 $tableClause .= ' ' . $joinedTable;
2035                                 if ( isset( $use_index[$alias] ) ) { // has USE INDEX?
2036                                         $use = $this->useIndexClause( implode( ',', (array)$use_index[$alias] ) );
2037                                         if ( $use != '' ) {
2038                                                 $tableClause .= ' ' . $use;
2039                                         }
2040                                 }
2041                                 if ( isset( $ignore_index[$alias] ) ) { // has IGNORE INDEX?
2042                                         $ignore = $this->ignoreIndexClause(
2043                                                 implode( ',', (array)$ignore_index[$alias] ) );
2044                                         if ( $ignore != '' ) {
2045                                                 $tableClause .= ' ' . $ignore;
2046                                         }
2047                                 }
2048                                 $on = $this->makeList( (array)$conds, self::LIST_AND );
2049                                 if ( $on != '' ) {
2050                                         $tableClause .= ' ON (' . $on . ')';
2051                                 }
2052
2053                                 $retJOIN[] = $tableClause;
2054                         } elseif ( isset( $use_index[$alias] ) ) {
2055                                 // Is there an INDEX clause for this table?
2056                                 $tableClause = $joinedTable;
2057                                 $tableClause .= ' ' . $this->useIndexClause(
2058                                                 implode( ',', (array)$use_index[$alias] )
2059                                         );
2060
2061                                 $ret[] = $tableClause;
2062                         } elseif ( isset( $ignore_index[$alias] ) ) {
2063                                 // Is there an INDEX clause for this table?
2064                                 $tableClause = $joinedTable;
2065                                 $tableClause .= ' ' . $this->ignoreIndexClause(
2066                                                 implode( ',', (array)$ignore_index[$alias] )
2067                                         );
2068
2069                                 $ret[] = $tableClause;
2070                         } else {
2071                                 $tableClause = $joinedTable;
2072
2073                                 $ret[] = $tableClause;
2074                         }
2075                 }
2076
2077                 // We can't separate explicit JOIN clauses with ',', use ' ' for those
2078                 $implicitJoins = !empty( $ret ) ? implode( ',', $ret ) : "";
2079                 $explicitJoins = !empty( $retJOIN ) ? implode( ' ', $retJOIN ) : "";
2080
2081                 // Compile our final table clause
2082                 return implode( ' ', [ $implicitJoins, $explicitJoins ] );
2083         }
2084
2085         /**
2086          * Allows for index remapping in queries where this is not consistent across DBMS
2087          *
2088          * @param string $index
2089          * @return string
2090          */
2091         protected function indexName( $index ) {
2092                 return $index;
2093         }
2094
2095         public function addQuotes( $s ) {
2096                 if ( $s instanceof Blob ) {
2097                         $s = $s->fetch();
2098                 }
2099                 if ( $s === null ) {
2100                         return 'NULL';
2101                 } elseif ( is_bool( $s ) ) {
2102                         return (int)$s;
2103                 } else {
2104                         # This will also quote numeric values. This should be harmless,
2105                         # and protects against weird problems that occur when they really
2106                         # _are_ strings such as article titles and string->number->string
2107                         # conversion is not 1:1.
2108                         return "'" . $this->strencode( $s ) . "'";
2109                 }
2110         }
2111
2112         /**
2113          * Quotes an identifier using `backticks` or "double quotes" depending on the database type.
2114          * MySQL uses `backticks` while basically everything else uses double quotes.
2115          * Since MySQL is the odd one out here the double quotes are our generic
2116          * and we implement backticks in DatabaseMysqlBase.
2117          *
2118          * @param string $s
2119          * @return string
2120          */
2121         public function addIdentifierQuotes( $s ) {
2122                 return '"' . str_replace( '"', '""', $s ) . '"';
2123         }
2124
2125         /**
2126          * Returns if the given identifier looks quoted or not according to
2127          * the database convention for quoting identifiers .
2128          *
2129          * @note Do not use this to determine if untrusted input is safe.
2130          *   A malicious user can trick this function.
2131          * @param string $name
2132          * @return bool
2133          */
2134         public function isQuotedIdentifier( $name ) {
2135                 return $name[0] == '"' && substr( $name, -1, 1 ) == '"';
2136         }
2137
2138         /**
2139          * @param string $s
2140          * @param string $escapeChar
2141          * @return string
2142          */
2143         protected function escapeLikeInternal( $s, $escapeChar = '`' ) {
2144                 return str_replace( [ $escapeChar, '%', '_' ],
2145                         [ "{$escapeChar}{$escapeChar}", "{$escapeChar}%", "{$escapeChar}_" ],
2146                         $s );
2147         }
2148
2149         public function buildLike() {
2150                 $params = func_get_args();
2151
2152                 if ( count( $params ) > 0 && is_array( $params[0] ) ) {
2153                         $params = $params[0];
2154                 }
2155
2156                 $s = '';
2157
2158                 // We use ` instead of \ as the default LIKE escape character, since addQuotes()
2159                 // may escape backslashes, creating problems of double escaping. The `
2160                 // character has good cross-DBMS compatibility, avoiding special operators
2161                 // in MS SQL like ^ and %
2162                 $escapeChar = '`';
2163
2164                 foreach ( $params as $value ) {
2165                         if ( $value instanceof LikeMatch ) {
2166                                 $s .= $value->toString();
2167                         } else {
2168                                 $s .= $this->escapeLikeInternal( $value, $escapeChar );
2169                         }
2170                 }
2171
2172                 return ' LIKE ' . $this->addQuotes( $s ) . ' ESCAPE ' . $this->addQuotes( $escapeChar ) . ' ';
2173         }
2174
2175         public function anyChar() {
2176                 return new LikeMatch( '_' );
2177         }
2178
2179         public function anyString() {
2180                 return new LikeMatch( '%' );
2181         }
2182
2183         public function nextSequenceValue( $seqName ) {
2184                 return null;
2185         }
2186
2187         /**
2188          * USE INDEX clause. Unlikely to be useful for anything but MySQL. This
2189          * is only needed because a) MySQL must be as efficient as possible due to
2190          * its use on Wikipedia, and b) MySQL 4.0 is kind of dumb sometimes about
2191          * which index to pick. Anyway, other databases might have different
2192          * indexes on a given table. So don't bother overriding this unless you're
2193          * MySQL.
2194          * @param string $index
2195          * @return string
2196          */
2197         public function useIndexClause( $index ) {
2198                 return '';
2199         }
2200
2201         /**
2202          * IGNORE INDEX clause. Unlikely to be useful for anything but MySQL. This
2203          * is only needed because a) MySQL must be as efficient as possible due to
2204          * its use on Wikipedia, and b) MySQL 4.0 is kind of dumb sometimes about
2205          * which index to pick. Anyway, other databases might have different
2206          * indexes on a given table. So don't bother overriding this unless you're
2207          * MySQL.
2208          * @param string $index
2209          * @return string
2210          */
2211         public function ignoreIndexClause( $index ) {
2212                 return '';
2213         }
2214
2215         public function replace( $table, $uniqueIndexes, $rows, $fname = __METHOD__ ) {
2216                 $quotedTable = $this->tableName( $table );
2217
2218                 if ( count( $rows ) == 0 ) {
2219                         return;
2220                 }
2221
2222                 # Single row case
2223                 if ( !is_array( reset( $rows ) ) ) {
2224                         $rows = [ $rows ];
2225                 }
2226
2227                 // @FXIME: this is not atomic, but a trx would break affectedRows()
2228                 foreach ( $rows as $row ) {
2229                         # Delete rows which collide
2230                         if ( $uniqueIndexes ) {
2231                                 $sql = "DELETE FROM $quotedTable WHERE ";
2232                                 $first = true;
2233                                 foreach ( $uniqueIndexes as $index ) {
2234                                         if ( $first ) {
2235                                                 $first = false;
2236                                                 $sql .= '( ';
2237                                         } else {
2238                                                 $sql .= ' ) OR ( ';
2239                                         }
2240                                         if ( is_array( $index ) ) {
2241                                                 $first2 = true;
2242                                                 foreach ( $index as $col ) {
2243                                                         if ( $first2 ) {
2244                                                                 $first2 = false;
2245                                                         } else {
2246                                                                 $sql .= ' AND ';
2247                                                         }
2248                                                         $sql .= $col . '=' . $this->addQuotes( $row[$col] );
2249                                                 }
2250                                         } else {
2251                                                 $sql .= $index . '=' . $this->addQuotes( $row[$index] );
2252                                         }
2253                                 }
2254                                 $sql .= ' )';
2255                                 $this->query( $sql, $fname );
2256                         }
2257
2258                         # Now insert the row
2259                         $this->insert( $table, $row, $fname );
2260                 }
2261         }
2262
2263         /**
2264          * REPLACE query wrapper for MySQL and SQLite, which have a native REPLACE
2265          * statement.
2266          *
2267          * @param string $table Table name
2268          * @param array|string $rows Row(s) to insert
2269          * @param string $fname Caller function name
2270          *
2271          * @return ResultWrapper
2272          */
2273         protected function nativeReplace( $table, $rows, $fname ) {
2274                 $table = $this->tableName( $table );
2275
2276                 # Single row case
2277                 if ( !is_array( reset( $rows ) ) ) {
2278                         $rows = [ $rows ];
2279                 }
2280
2281                 $sql = "REPLACE INTO $table (" . implode( ',', array_keys( $rows[0] ) ) . ') VALUES ';
2282                 $first = true;
2283
2284                 foreach ( $rows as $row ) {
2285                         if ( $first ) {
2286                                 $first = false;
2287                         } else {
2288                                 $sql .= ',';
2289                         }
2290
2291                         $sql .= '(' . $this->makeList( $row ) . ')';
2292                 }
2293
2294                 return $this->query( $sql, $fname );
2295         }
2296
2297         public function upsert( $table, array $rows, array $uniqueIndexes, array $set,
2298                 $fname = __METHOD__
2299         ) {
2300                 if ( !count( $rows ) ) {
2301                         return true; // nothing to do
2302                 }
2303
2304                 if ( !is_array( reset( $rows ) ) ) {
2305                         $rows = [ $rows ];
2306                 }
2307
2308                 if ( count( $uniqueIndexes ) ) {
2309                         $clauses = []; // list WHERE clauses that each identify a single row
2310                         foreach ( $rows as $row ) {
2311                                 foreach ( $uniqueIndexes as $index ) {
2312                                         $index = is_array( $index ) ? $index : [ $index ]; // columns
2313                                         $rowKey = []; // unique key to this row
2314                                         foreach ( $index as $column ) {
2315                                                 $rowKey[$column] = $row[$column];
2316                                         }
2317                                         $clauses[] = $this->makeList( $rowKey, self::LIST_AND );
2318                                 }
2319                         }
2320                         $where = [ $this->makeList( $clauses, self::LIST_OR ) ];
2321                 } else {
2322                         $where = false;
2323                 }
2324
2325                 $useTrx = !$this->mTrxLevel;
2326                 if ( $useTrx ) {
2327                         $this->begin( $fname, self::TRANSACTION_INTERNAL );
2328                 }
2329                 try {
2330                         # Update any existing conflicting row(s)
2331                         if ( $where !== false ) {
2332                                 $ok = $this->update( $table, $set, $where, $fname );
2333                         } else {
2334                                 $ok = true;
2335                         }
2336                         # Now insert any non-conflicting row(s)
2337                         $ok = $this->insert( $table, $rows, $fname, [ 'IGNORE' ] ) && $ok;
2338                 } catch ( Exception $e ) {
2339                         if ( $useTrx ) {
2340                                 $this->rollback( $fname, self::FLUSHING_INTERNAL );
2341                         }
2342                         throw $e;
2343                 }
2344                 if ( $useTrx ) {
2345                         $this->commit( $fname, self::FLUSHING_INTERNAL );
2346                 }
2347
2348                 return $ok;
2349         }
2350
2351         public function deleteJoin( $delTable, $joinTable, $delVar, $joinVar, $conds,
2352                 $fname = __METHOD__
2353         ) {
2354                 if ( !$conds ) {
2355                         throw new DBUnexpectedError( $this, __METHOD__ . ' called with empty $conds' );
2356                 }
2357
2358                 $delTable = $this->tableName( $delTable );
2359                 $joinTable = $this->tableName( $joinTable );
2360                 $sql = "DELETE FROM $delTable WHERE $delVar IN (SELECT $joinVar FROM $joinTable ";
2361                 if ( $conds != '*' ) {
2362                         $sql .= 'WHERE ' . $this->makeList( $conds, self::LIST_AND );
2363                 }
2364                 $sql .= ')';
2365
2366                 $this->query( $sql, $fname );
2367         }
2368
2369         public function textFieldSize( $table, $field ) {
2370                 $table = $this->tableName( $table );
2371                 $sql = "SHOW COLUMNS FROM $table LIKE \"$field\";";
2372                 $res = $this->query( $sql, __METHOD__ );
2373                 $row = $this->fetchObject( $res );
2374
2375                 $m = [];
2376
2377                 if ( preg_match( '/\((.*)\)/', $row->Type, $m ) ) {
2378                         $size = $m[1];
2379                 } else {
2380                         $size = -1;
2381                 }
2382
2383                 return $size;
2384         }
2385
2386         public function delete( $table, $conds, $fname = __METHOD__ ) {
2387                 if ( !$conds ) {
2388                         throw new DBUnexpectedError( $this, __METHOD__ . ' called with no conditions' );
2389                 }
2390
2391                 $table = $this->tableName( $table );
2392                 $sql = "DELETE FROM $table";
2393
2394                 if ( $conds != '*' ) {
2395                         if ( is_array( $conds ) ) {
2396                                 $conds = $this->makeList( $conds, self::LIST_AND );
2397                         }
2398                         $sql .= ' WHERE ' . $conds;
2399                 }
2400
2401                 return $this->query( $sql, $fname );
2402         }
2403
2404         public function insertSelect(
2405                 $destTable, $srcTable, $varMap, $conds,
2406                 $fname = __METHOD__, $insertOptions = [], $selectOptions = [], $selectJoinConds = []
2407         ) {
2408                 if ( $this->cliMode ) {
2409                         // For massive migrations with downtime, we don't want to select everything
2410                         // into memory and OOM, so do all this native on the server side if possible.
2411                         return $this->nativeInsertSelect(
2412                                 $destTable,
2413                                 $srcTable,
2414                                 $varMap,
2415                                 $conds,
2416                                 $fname,
2417                                 $insertOptions,
2418                                 $selectOptions,
2419                                 $selectJoinConds
2420                         );
2421                 }
2422
2423                 return $this->nonNativeInsertSelect(
2424                         $destTable,
2425                         $srcTable,
2426                         $varMap,
2427                         $conds,
2428                         $fname,
2429                         $insertOptions,
2430                         $selectOptions,
2431                         $selectJoinConds
2432                 );
2433         }
2434
2435         /**
2436          * Implementation of insertSelect() based on select() and insert()
2437          *
2438          * @see IDatabase::insertSelect()
2439          * @since 1.30
2440          * @param string $destTable
2441          * @param string|array $srcTable
2442          * @param array $varMap
2443          * @param array $conds
2444          * @param string $fname
2445          * @param array $insertOptions
2446          * @param array $selectOptions
2447          * @param array $selectJoinConds
2448          * @return bool
2449          */
2450         protected function nonNativeInsertSelect( $destTable, $srcTable, $varMap, $conds,
2451                 $fname = __METHOD__,
2452                 $insertOptions = [], $selectOptions = [], $selectJoinConds = []
2453         ) {
2454                 // For web requests, do a locking SELECT and then INSERT. This puts the SELECT burden
2455                 // on only the master (without needing row-based-replication). It also makes it easy to
2456                 // know how big the INSERT is going to be.
2457                 $fields = [];
2458                 foreach ( $varMap as $dstColumn => $sourceColumnOrSql ) {
2459                         $fields[] = $this->fieldNameWithAlias( $sourceColumnOrSql, $dstColumn );
2460                 }
2461                 $selectOptions[] = 'FOR UPDATE';
2462                 $res = $this->select(
2463                         $srcTable, implode( ',', $fields ), $conds, $fname, $selectOptions, $selectJoinConds
2464                 );
2465                 if ( !$res ) {
2466                         return false;
2467                 }
2468
2469                 $rows = [];
2470                 foreach ( $res as $row ) {
2471                         $rows[] = (array)$row;
2472                 }
2473
2474                 return $this->insert( $destTable, $rows, $fname, $insertOptions );
2475         }
2476
2477         /**
2478          * Native server-side implementation of insertSelect() for situations where
2479          * we don't want to select everything into memory
2480          *
2481          * @see IDatabase::insertSelect()
2482          * @param string $destTable
2483          * @param string|array $srcTable
2484          * @param array $varMap
2485          * @param array $conds
2486          * @param string $fname
2487          * @param array $insertOptions
2488          * @param array $selectOptions
2489          * @param array $selectJoinConds
2490          * @return bool
2491          */
2492         protected function nativeInsertSelect( $destTable, $srcTable, $varMap, $conds,
2493                 $fname = __METHOD__,
2494                 $insertOptions = [], $selectOptions = [], $selectJoinConds = []
2495         ) {
2496                 $destTable = $this->tableName( $destTable );
2497
2498                 if ( !is_array( $insertOptions ) ) {
2499                         $insertOptions = [ $insertOptions ];
2500                 }
2501
2502                 $insertOptions = $this->makeInsertOptions( $insertOptions );
2503
2504                 $selectSql = $this->selectSQLText(
2505                         $srcTable,
2506                         array_values( $varMap ),
2507                         $conds,
2508                         $fname,
2509                         $selectOptions,
2510                         $selectJoinConds
2511                 );
2512
2513                 $sql = "INSERT $insertOptions" .
2514                         " INTO $destTable (" . implode( ',', array_keys( $varMap ) ) . ') ' .
2515                         $selectSql;
2516
2517                 return $this->query( $sql, $fname );
2518         }
2519
2520         /**
2521          * Construct a LIMIT query with optional offset. This is used for query
2522          * pages. The SQL should be adjusted so that only the first $limit rows
2523          * are returned. If $offset is provided as well, then the first $offset
2524          * rows should be discarded, and the next $limit rows should be returned.
2525          * If the result of the query is not ordered, then the rows to be returned
2526          * are theoretically arbitrary.
2527          *
2528          * $sql is expected to be a SELECT, if that makes a difference.
2529          *
2530          * The version provided by default works in MySQL and SQLite. It will very
2531          * likely need to be overridden for most other DBMSes.
2532          *
2533          * @param string $sql SQL query we will append the limit too
2534          * @param int $limit The SQL limit
2535          * @param int|bool $offset The SQL offset (default false)
2536          * @throws DBUnexpectedError
2537          * @return string
2538          */
2539         public function limitResult( $sql, $limit, $offset = false ) {
2540                 if ( !is_numeric( $limit ) ) {
2541                         throw new DBUnexpectedError( $this,
2542                                 "Invalid non-numeric limit passed to limitResult()\n" );
2543                 }
2544
2545                 return "$sql LIMIT "
2546                 . ( ( is_numeric( $offset ) && $offset != 0 ) ? "{$offset}," : "" )
2547                 . "{$limit} ";
2548         }
2549
2550         public function unionSupportsOrderAndLimit() {
2551                 return true; // True for almost every DB supported
2552         }
2553
2554         public function unionQueries( $sqls, $all ) {
2555                 $glue = $all ? ') UNION ALL (' : ') UNION (';
2556
2557                 return '(' . implode( $glue, $sqls ) . ')';
2558         }
2559
2560         public function unionConditionPermutations(
2561                 $table, $vars, array $permute_conds, $extra_conds = '', $fname = __METHOD__,
2562                 $options = [], $join_conds = []
2563         ) {
2564                 // First, build the Cartesian product of $permute_conds
2565                 $conds = [ [] ];
2566                 foreach ( $permute_conds as $field => $values ) {
2567                         if ( !$values ) {
2568                                 // Skip empty $values
2569                                 continue;
2570                         }
2571                         $values = array_unique( $values ); // For sanity
2572                         $newConds = [];
2573                         foreach ( $conds as $cond ) {
2574                                 foreach ( $values as $value ) {
2575                                         $cond[$field] = $value;
2576                                         $newConds[] = $cond; // Arrays are by-value, not by-reference, so this works
2577                                 }
2578                         }
2579                         $conds = $newConds;
2580                 }
2581
2582                 $extra_conds = $extra_conds === '' ? [] : (array)$extra_conds;
2583
2584                 // If there's just one condition and no subordering, hand off to
2585                 // selectSQLText directly.
2586                 if ( count( $conds ) === 1 &&
2587                         ( !isset( $options['INNER ORDER BY'] ) || !$this->unionSupportsOrderAndLimit() )
2588                 ) {
2589                         return $this->selectSQLText(
2590                                 $table, $vars, $conds[0] + $extra_conds, $fname, $options, $join_conds
2591                         );
2592                 }
2593
2594                 // Otherwise, we need to pull out the order and limit to apply after
2595                 // the union. Then build the SQL queries for each set of conditions in
2596                 // $conds. Then union them together (using UNION ALL, because the
2597                 // product *should* already be distinct).
2598                 $orderBy = $this->makeOrderBy( $options );
2599                 $limit = isset( $options['LIMIT'] ) ? $options['LIMIT'] : null;
2600                 $offset = isset( $options['OFFSET'] ) ? $options['OFFSET'] : false;
2601                 $all = empty( $options['NOTALL'] ) && !in_array( 'NOTALL', $options );
2602                 if ( !$this->unionSupportsOrderAndLimit() ) {
2603                         unset( $options['ORDER BY'], $options['LIMIT'], $options['OFFSET'] );
2604                 } else {
2605                         if ( array_key_exists( 'INNER ORDER BY', $options ) ) {
2606                                 $options['ORDER BY'] = $options['INNER ORDER BY'];
2607                         }
2608                         if ( $limit !== null && is_numeric( $offset ) && $offset != 0 ) {
2609                                 // We need to increase the limit by the offset rather than
2610                                 // using the offset directly, otherwise it'll skip incorrectly
2611                                 // in the subqueries.
2612                                 $options['LIMIT'] = $limit + $offset;
2613                                 unset( $options['OFFSET'] );
2614                         }
2615                 }
2616
2617                 $sqls = [];
2618                 foreach ( $conds as $cond ) {
2619                         $sqls[] = $this->selectSQLText(
2620                                 $table, $vars, $cond + $extra_conds, $fname, $options, $join_conds
2621                         );
2622                 }
2623                 $sql = $this->unionQueries( $sqls, $all ) . $orderBy;
2624                 if ( $limit !== null ) {
2625                         $sql = $this->limitResult( $sql, $limit, $offset );
2626                 }
2627
2628                 return $sql;
2629         }
2630
2631         public function conditional( $cond, $trueVal, $falseVal ) {
2632                 if ( is_array( $cond ) ) {
2633                         $cond = $this->makeList( $cond, self::LIST_AND );
2634                 }
2635
2636                 return " (CASE WHEN $cond THEN $trueVal ELSE $falseVal END) ";
2637         }
2638
2639         public function strreplace( $orig, $old, $new ) {
2640                 return "REPLACE({$orig}, {$old}, {$new})";
2641         }
2642
2643         public function getServerUptime() {
2644                 return 0;
2645         }
2646
2647         public function wasDeadlock() {
2648                 return false;
2649         }
2650
2651         public function wasLockTimeout() {
2652                 return false;
2653         }
2654
2655         public function wasErrorReissuable() {
2656                 return false;
2657         }
2658
2659         public function wasReadOnlyError() {
2660                 return false;
2661         }
2662
2663         /**
2664          * Do not use this method outside of Database/DBError classes
2665          *
2666          * @param int|string $errno
2667          * @return bool Whether the given query error was a connection drop
2668          */
2669         public function wasConnectionError( $errno ) {
2670                 return false;
2671         }
2672
2673         public function deadlockLoop() {
2674                 $args = func_get_args();
2675                 $function = array_shift( $args );
2676                 $tries = self::DEADLOCK_TRIES;
2677
2678                 $this->begin( __METHOD__ );
2679
2680                 $retVal = null;
2681                 /** @var Exception $e */
2682                 $e = null;
2683                 do {
2684                         try {
2685                                 $retVal = call_user_func_array( $function, $args );
2686                                 break;
2687                         } catch ( DBQueryError $e ) {
2688                                 if ( $this->wasDeadlock() ) {
2689                                         // Retry after a randomized delay
2690                                         usleep( mt_rand( self::DEADLOCK_DELAY_MIN, self::DEADLOCK_DELAY_MAX ) );
2691                                 } else {
2692                                         // Throw the error back up
2693                                         throw $e;
2694                                 }
2695                         }
2696                 } while ( --$tries > 0 );
2697
2698                 if ( $tries <= 0 ) {
2699                         // Too many deadlocks; give up
2700                         $this->rollback( __METHOD__ );
2701                         throw $e;
2702                 } else {
2703                         $this->commit( __METHOD__ );
2704
2705                         return $retVal;
2706                 }
2707         }
2708
2709         public function masterPosWait( DBMasterPos $pos, $timeout ) {
2710                 # Real waits are implemented in the subclass.
2711                 return 0;
2712         }
2713
2714         public function getReplicaPos() {
2715                 # Stub
2716                 return false;
2717         }
2718
2719         public function getMasterPos() {
2720                 # Stub
2721                 return false;
2722         }
2723
2724         public function serverIsReadOnly() {
2725                 return false;
2726         }
2727
2728         final public function onTransactionResolution( callable $callback, $fname = __METHOD__ ) {
2729                 if ( !$this->mTrxLevel ) {
2730                         throw new DBUnexpectedError( $this, "No transaction is active." );
2731                 }
2732                 $this->mTrxEndCallbacks[] = [ $callback, $fname ];
2733         }
2734
2735         final public function onTransactionIdle( callable $callback, $fname = __METHOD__ ) {
2736                 $this->mTrxIdleCallbacks[] = [ $callback, $fname ];
2737                 if ( !$this->mTrxLevel ) {
2738                         $this->runOnTransactionIdleCallbacks( self::TRIGGER_IDLE );
2739                 }
2740         }
2741
2742         final public function onTransactionPreCommitOrIdle( callable $callback, $fname = __METHOD__ ) {
2743                 if ( $this->mTrxLevel || $this->getFlag( self::DBO_TRX ) ) {
2744                         // As long as DBO_TRX is set, writes will accumulate until the load balancer issues
2745                         // an implicit commit of all peer databases. This is true even if a transaction has
2746                         // not yet been triggered by writes; make sure $callback runs *after* any such writes.
2747                         $this->mTrxPreCommitCallbacks[] = [ $callback, $fname ];
2748                 } else {
2749                         // No transaction is active nor will start implicitly, so make one for this callback
2750                         $this->startAtomic( __METHOD__ );
2751                         try {
2752                                 call_user_func( $callback );
2753                                 $this->endAtomic( __METHOD__ );
2754                         } catch ( Exception $e ) {
2755                                 $this->rollback( __METHOD__, self::FLUSHING_INTERNAL );
2756                                 throw $e;
2757                         }
2758                 }
2759         }
2760
2761         final public function setTransactionListener( $name, callable $callback = null ) {
2762                 if ( $callback ) {
2763                         $this->mTrxRecurringCallbacks[$name] = $callback;
2764                 } else {
2765                         unset( $this->mTrxRecurringCallbacks[$name] );
2766                 }
2767         }
2768
2769         /**
2770          * Whether to disable running of post-COMMIT/ROLLBACK callbacks
2771          *
2772          * This method should not be used outside of Database/LoadBalancer
2773          *
2774          * @param bool $suppress
2775          * @since 1.28
2776          */
2777         final public function setTrxEndCallbackSuppression( $suppress ) {
2778                 $this->mTrxEndCallbacksSuppressed = $suppress;
2779         }
2780
2781         /**
2782          * Actually run and consume any "on transaction idle/resolution" callbacks.
2783          *
2784          * This method should not be used outside of Database/LoadBalancer
2785          *
2786          * @param int $trigger IDatabase::TRIGGER_* constant
2787          * @since 1.20
2788          * @throws Exception
2789          */
2790         public function runOnTransactionIdleCallbacks( $trigger ) {
2791                 if ( $this->mTrxEndCallbacksSuppressed ) {
2792                         return;
2793                 }
2794
2795                 $autoTrx = $this->getFlag( self::DBO_TRX ); // automatic begin() enabled?
2796                 /** @var Exception $e */
2797                 $e = null; // first exception
2798                 do { // callbacks may add callbacks :)
2799                         $callbacks = array_merge(
2800                                 $this->mTrxIdleCallbacks,
2801                                 $this->mTrxEndCallbacks // include "transaction resolution" callbacks
2802                         );
2803                         $this->mTrxIdleCallbacks = []; // consumed (and recursion guard)
2804                         $this->mTrxEndCallbacks = []; // consumed (recursion guard)
2805                         foreach ( $callbacks as $callback ) {
2806                                 try {
2807                                         list( $phpCallback ) = $callback;
2808                                         $this->clearFlag( self::DBO_TRX ); // make each query its own transaction
2809                                         call_user_func_array( $phpCallback, [ $trigger ] );
2810                                         if ( $autoTrx ) {
2811                                                 $this->setFlag( self::DBO_TRX ); // restore automatic begin()
2812                                         } else {
2813                                                 $this->clearFlag( self::DBO_TRX ); // restore auto-commit
2814                                         }
2815                                 } catch ( Exception $ex ) {
2816                                         call_user_func( $this->errorLogger, $ex );
2817                                         $e = $e ?: $ex;
2818                                         // Some callbacks may use startAtomic/endAtomic, so make sure
2819                                         // their transactions are ended so other callbacks don't fail
2820                                         if ( $this->trxLevel() ) {
2821                                                 $this->rollback( __METHOD__, self::FLUSHING_INTERNAL );
2822                                         }
2823                                 }
2824                         }
2825                 } while ( count( $this->mTrxIdleCallbacks ) );
2826
2827                 if ( $e instanceof Exception ) {
2828                         throw $e; // re-throw any first exception
2829                 }
2830         }
2831
2832         /**
2833          * Actually run and consume any "on transaction pre-commit" callbacks.
2834          *
2835          * This method should not be used outside of Database/LoadBalancer
2836          *
2837          * @since 1.22
2838          * @throws Exception
2839          */
2840         public function runOnTransactionPreCommitCallbacks() {
2841                 $e = null; // first exception
2842                 do { // callbacks may add callbacks :)
2843                         $callbacks = $this->mTrxPreCommitCallbacks;
2844                         $this->mTrxPreCommitCallbacks = []; // consumed (and recursion guard)
2845                         foreach ( $callbacks as $callback ) {
2846                                 try {
2847                                         list( $phpCallback ) = $callback;
2848                                         call_user_func( $phpCallback );
2849                                 } catch ( Exception $ex ) {
2850                                         call_user_func( $this->errorLogger, $ex );
2851                                         $e = $e ?: $ex;
2852                                 }
2853                         }
2854                 } while ( count( $this->mTrxPreCommitCallbacks ) );
2855
2856                 if ( $e instanceof Exception ) {
2857                         throw $e; // re-throw any first exception
2858                 }
2859         }
2860
2861         /**
2862          * Actually run any "transaction listener" callbacks.
2863          *
2864          * This method should not be used outside of Database/LoadBalancer
2865          *
2866          * @param int $trigger IDatabase::TRIGGER_* constant
2867          * @throws Exception
2868          * @since 1.20
2869          */
2870         public function runTransactionListenerCallbacks( $trigger ) {
2871                 if ( $this->mTrxEndCallbacksSuppressed ) {
2872                         return;
2873                 }
2874
2875                 /** @var Exception $e */
2876                 $e = null; // first exception
2877
2878                 foreach ( $this->mTrxRecurringCallbacks as $phpCallback ) {
2879                         try {
2880                                 $phpCallback( $trigger, $this );
2881                         } catch ( Exception $ex ) {
2882                                 call_user_func( $this->errorLogger, $ex );
2883                                 $e = $e ?: $ex;
2884                         }
2885                 }
2886
2887                 if ( $e instanceof Exception ) {
2888                         throw $e; // re-throw any first exception
2889                 }
2890         }
2891
2892         final public function startAtomic( $fname = __METHOD__ ) {
2893                 if ( !$this->mTrxLevel ) {
2894                         $this->begin( $fname, self::TRANSACTION_INTERNAL );
2895                         // If DBO_TRX is set, a series of startAtomic/endAtomic pairs will result
2896                         // in all changes being in one transaction to keep requests transactional.
2897                         if ( !$this->getFlag( self::DBO_TRX ) ) {
2898                                 $this->mTrxAutomaticAtomic = true;
2899                         }
2900                 }
2901
2902                 $this->mTrxAtomicLevels[] = $fname;
2903         }
2904
2905         final public function endAtomic( $fname = __METHOD__ ) {
2906                 if ( !$this->mTrxLevel ) {
2907                         throw new DBUnexpectedError( $this, "No atomic transaction is open (got $fname)." );
2908                 }
2909                 if ( !$this->mTrxAtomicLevels ||
2910                         array_pop( $this->mTrxAtomicLevels ) !== $fname
2911                 ) {
2912                         throw new DBUnexpectedError( $this, "Invalid atomic section ended (got $fname)." );
2913                 }
2914
2915                 if ( !$this->mTrxAtomicLevels && $this->mTrxAutomaticAtomic ) {
2916                         $this->commit( $fname, self::FLUSHING_INTERNAL );
2917                 }
2918         }
2919
2920         final public function doAtomicSection( $fname, callable $callback ) {
2921                 $this->startAtomic( $fname );
2922                 try {
2923                         $res = call_user_func_array( $callback, [ $this, $fname ] );
2924                 } catch ( Exception $e ) {
2925                         $this->rollback( $fname, self::FLUSHING_INTERNAL );
2926                         throw $e;
2927                 }
2928                 $this->endAtomic( $fname );
2929
2930                 return $res;
2931         }
2932
2933         final public function begin( $fname = __METHOD__, $mode = self::TRANSACTION_EXPLICIT ) {
2934                 // Protect against mismatched atomic section, transaction nesting, and snapshot loss
2935                 if ( $this->mTrxLevel ) {
2936                         if ( $this->mTrxAtomicLevels ) {
2937                                 $levels = implode( ', ', $this->mTrxAtomicLevels );
2938                                 $msg = "$fname: Got explicit BEGIN while atomic section(s) $levels are open.";
2939                                 throw new DBUnexpectedError( $this, $msg );
2940                         } elseif ( !$this->mTrxAutomatic ) {
2941                                 $msg = "$fname: Explicit transaction already active (from {$this->mTrxFname}).";
2942                                 throw new DBUnexpectedError( $this, $msg );
2943                         } else {
2944                                 // @TODO: make this an exception at some point
2945                                 $msg = "$fname: Implicit transaction already active (from {$this->mTrxFname}).";
2946                                 $this->queryLogger->error( $msg );
2947                                 return; // join the main transaction set
2948                         }
2949                 } elseif ( $this->getFlag( self::DBO_TRX ) && $mode !== self::TRANSACTION_INTERNAL ) {
2950                         // @TODO: make this an exception at some point
2951                         $msg = "$fname: Implicit transaction expected (DBO_TRX set).";
2952                         $this->queryLogger->error( $msg );
2953                         return; // let any writes be in the main transaction
2954                 }
2955
2956                 // Avoid fatals if close() was called
2957                 $this->assertOpen();
2958
2959                 $this->doBegin( $fname );
2960                 $this->mTrxTimestamp = microtime( true );
2961                 $this->mTrxFname = $fname;
2962                 $this->mTrxDoneWrites = false;
2963                 $this->mTrxAutomaticAtomic = false;
2964                 $this->mTrxAtomicLevels = [];
2965                 $this->mTrxShortId = sprintf( '%06x', mt_rand( 0, 0xffffff ) );
2966                 $this->mTrxWriteDuration = 0.0;
2967                 $this->mTrxWriteQueryCount = 0;
2968                 $this->mTrxWriteAffectedRows = 0;
2969                 $this->mTrxWriteAdjDuration = 0.0;
2970                 $this->mTrxWriteAdjQueryCount = 0;
2971                 $this->mTrxWriteCallers = [];
2972                 // First SELECT after BEGIN will establish the snapshot in REPEATABLE-READ.
2973                 // Get an estimate of the replica DB lag before then, treating estimate staleness
2974                 // as lag itself just to be safe
2975                 $status = $this->getApproximateLagStatus();
2976                 $this->mTrxReplicaLag = $status['lag'] + ( microtime( true ) - $status['since'] );
2977                 // T147697: make explicitTrxActive() return true until begin() finishes. This way, no
2978                 // caller will think its OK to muck around with the transaction just because startAtomic()
2979                 // has not yet completed (e.g. setting mTrxAtomicLevels).
2980                 $this->mTrxAutomatic = ( $mode === self::TRANSACTION_INTERNAL );
2981         }
2982
2983         /**
2984          * Issues the BEGIN command to the database server.
2985          *
2986          * @see Database::begin()
2987          * @param string $fname
2988          */
2989         protected function doBegin( $fname ) {
2990                 $this->query( 'BEGIN', $fname );
2991                 $this->mTrxLevel = 1;
2992         }
2993
2994         final public function commit( $fname = __METHOD__, $flush = '' ) {
2995                 if ( $this->mTrxLevel && $this->mTrxAtomicLevels ) {
2996                         // There are still atomic sections open. This cannot be ignored
2997                         $levels = implode( ', ', $this->mTrxAtomicLevels );
2998                         throw new DBUnexpectedError(
2999                                 $this,
3000                                 "$fname: Got COMMIT while atomic sections $levels are still open."
3001                         );
3002                 }
3003
3004                 if ( $flush === self::FLUSHING_INTERNAL || $flush === self::FLUSHING_ALL_PEERS ) {
3005                         if ( !$this->mTrxLevel ) {
3006                                 return; // nothing to do
3007                         } elseif ( !$this->mTrxAutomatic ) {
3008                                 throw new DBUnexpectedError(
3009                                         $this,
3010                                         "$fname: Flushing an explicit transaction, getting out of sync."
3011                                 );
3012                         }
3013                 } else {
3014                         if ( !$this->mTrxLevel ) {
3015                                 $this->queryLogger->error(
3016                                         "$fname: No transaction to commit, something got out of sync." );
3017                                 return; // nothing to do
3018                         } elseif ( $this->mTrxAutomatic ) {
3019                                 // @TODO: make this an exception at some point
3020                                 $msg = "$fname: Explicit commit of implicit transaction.";
3021                                 $this->queryLogger->error( $msg );
3022                                 return; // wait for the main transaction set commit round
3023                         }
3024                 }
3025
3026                 // Avoid fatals if close() was called
3027                 $this->assertOpen();
3028
3029                 $this->runOnTransactionPreCommitCallbacks();
3030                 $writeTime = $this->pendingWriteQueryDuration( self::ESTIMATE_DB_APPLY );
3031                 $this->doCommit( $fname );
3032                 if ( $this->mTrxDoneWrites ) {
3033                         $this->mLastWriteTime = microtime( true );
3034                         $this->trxProfiler->transactionWritingOut(
3035                                 $this->mServer,
3036                                 $this->mDBname,
3037                                 $this->mTrxShortId,
3038                                 $writeTime,
3039                                 $this->mTrxWriteAffectedRows
3040                         );
3041                 }
3042
3043                 $this->runOnTransactionIdleCallbacks( self::TRIGGER_COMMIT );
3044                 $this->runTransactionListenerCallbacks( self::TRIGGER_COMMIT );
3045         }
3046
3047         /**
3048          * Issues the COMMIT command to the database server.
3049          *
3050          * @see Database::commit()
3051          * @param string $fname
3052          */
3053         protected function doCommit( $fname ) {
3054                 if ( $this->mTrxLevel ) {
3055                         $this->query( 'COMMIT', $fname );
3056                         $this->mTrxLevel = 0;
3057                 }
3058         }
3059
3060         final public function rollback( $fname = __METHOD__, $flush = '' ) {
3061                 if ( $flush === self::FLUSHING_INTERNAL || $flush === self::FLUSHING_ALL_PEERS ) {
3062                         if ( !$this->mTrxLevel ) {
3063                                 return; // nothing to do
3064                         }
3065                 } else {
3066                         if ( !$this->mTrxLevel ) {
3067                                 $this->queryLogger->error(
3068                                         "$fname: No transaction to rollback, something got out of sync." );
3069                                 return; // nothing to do
3070                         } elseif ( $this->getFlag( self::DBO_TRX ) ) {
3071                                 throw new DBUnexpectedError(
3072                                         $this,
3073                                         "$fname: Expected mass rollback of all peer databases (DBO_TRX set)."
3074                                 );
3075                         }
3076                 }
3077
3078                 // Avoid fatals if close() was called
3079                 $this->assertOpen();
3080
3081                 $this->doRollback( $fname );
3082                 $this->mTrxAtomicLevels = [];
3083                 if ( $this->mTrxDoneWrites ) {
3084                         $this->trxProfiler->transactionWritingOut(
3085                                 $this->mServer,
3086                                 $this->mDBname,
3087                                 $this->mTrxShortId
3088                         );
3089                 }
3090
3091                 $this->mTrxIdleCallbacks = []; // clear
3092                 $this->mTrxPreCommitCallbacks = []; // clear
3093                 try {
3094                         $this->runOnTransactionIdleCallbacks( self::TRIGGER_ROLLBACK );
3095                 } catch ( Exception $e ) {
3096                         // already logged; finish and let LoadBalancer move on during mass-rollback
3097                 }
3098                 try {
3099                         $this->runTransactionListenerCallbacks( self::TRIGGER_ROLLBACK );
3100                 } catch ( Exception $e ) {
3101                         // already logged; let LoadBalancer move on during mass-rollback
3102                 }
3103         }
3104
3105         /**
3106          * Issues the ROLLBACK command to the database server.
3107          *
3108          * @see Database::rollback()
3109          * @param string $fname
3110          */
3111         protected function doRollback( $fname ) {
3112                 if ( $this->mTrxLevel ) {
3113                         # Disconnects cause rollback anyway, so ignore those errors
3114                         $ignoreErrors = true;
3115                         $this->query( 'ROLLBACK', $fname, $ignoreErrors );
3116                         $this->mTrxLevel = 0;
3117                 }
3118         }
3119
3120         public function flushSnapshot( $fname = __METHOD__ ) {
3121                 if ( $this->writesOrCallbacksPending() || $this->explicitTrxActive() ) {
3122                         // This only flushes transactions to clear snapshots, not to write data
3123                         $fnames = implode( ', ', $this->pendingWriteAndCallbackCallers() );
3124                         throw new DBUnexpectedError(
3125                                 $this,
3126                                 "$fname: Cannot flush snapshot because writes are pending ($fnames)."
3127                         );
3128                 }
3129
3130                 $this->commit( $fname, self::FLUSHING_INTERNAL );
3131         }
3132
3133         public function explicitTrxActive() {
3134                 return $this->mTrxLevel && ( $this->mTrxAtomicLevels || !$this->mTrxAutomatic );
3135         }
3136
3137         public function duplicateTableStructure(
3138                 $oldName, $newName, $temporary = false, $fname = __METHOD__
3139         ) {
3140                 throw new RuntimeException( __METHOD__ . ' is not implemented in descendant class' );
3141         }
3142
3143         public function listTables( $prefix = null, $fname = __METHOD__ ) {
3144                 throw new RuntimeException( __METHOD__ . ' is not implemented in descendant class' );
3145         }
3146
3147         public function listViews( $prefix = null, $fname = __METHOD__ ) {
3148                 throw new RuntimeException( __METHOD__ . ' is not implemented in descendant class' );
3149         }
3150
3151         public function timestamp( $ts = 0 ) {
3152                 $t = new ConvertibleTimestamp( $ts );
3153                 // Let errors bubble up to avoid putting garbage in the DB
3154                 return $t->getTimestamp( TS_MW );
3155         }
3156
3157         public function timestampOrNull( $ts = null ) {
3158                 if ( is_null( $ts ) ) {
3159                         return null;
3160                 } else {
3161                         return $this->timestamp( $ts );
3162                 }
3163         }
3164
3165         /**
3166          * Take the result from a query, and wrap it in a ResultWrapper if
3167          * necessary. Boolean values are passed through as is, to indicate success
3168          * of write queries or failure.
3169          *
3170          * Once upon a time, Database::query() returned a bare MySQL result
3171          * resource, and it was necessary to call this function to convert it to
3172          * a wrapper. Nowadays, raw database objects are never exposed to external
3173          * callers, so this is unnecessary in external code.
3174          *
3175          * @param bool|ResultWrapper|resource|object $result
3176          * @return bool|ResultWrapper
3177          */
3178         protected function resultObject( $result ) {
3179                 if ( !$result ) {
3180                         return false;
3181                 } elseif ( $result instanceof ResultWrapper ) {
3182                         return $result;
3183                 } elseif ( $result === true ) {
3184                         // Successful write query
3185                         return $result;
3186                 } else {
3187                         return new ResultWrapper( $this, $result );
3188                 }
3189         }
3190
3191         public function ping( &$rtt = null ) {
3192                 // Avoid hitting the server if it was hit recently
3193                 if ( $this->isOpen() && ( microtime( true ) - $this->lastPing ) < self::PING_TTL ) {
3194                         if ( !func_num_args() || $this->mRTTEstimate > 0 ) {
3195                                 $rtt = $this->mRTTEstimate;
3196                                 return true; // don't care about $rtt
3197                         }
3198                 }
3199
3200                 // This will reconnect if possible or return false if not
3201                 $this->clearFlag( self::DBO_TRX, self::REMEMBER_PRIOR );
3202                 $ok = ( $this->query( self::PING_QUERY, __METHOD__, true ) !== false );
3203                 $this->restoreFlags( self::RESTORE_PRIOR );
3204
3205                 if ( $ok ) {
3206                         $rtt = $this->mRTTEstimate;
3207                 }
3208
3209                 return $ok;
3210         }
3211
3212         /**
3213          * Close existing database connection and open a new connection
3214          *
3215          * @return bool True if new connection is opened successfully, false if error
3216          */
3217         protected function reconnect() {
3218                 $this->closeConnection();
3219                 $this->mOpened = false;
3220                 $this->mConn = false;
3221                 try {
3222                         $this->open( $this->mServer, $this->mUser, $this->mPassword, $this->mDBname );
3223                         $this->lastPing = microtime( true );
3224                         $ok = true;
3225                 } catch ( DBConnectionError $e ) {
3226                         $ok = false;
3227                 }
3228
3229                 return $ok;
3230         }
3231
3232         public function getSessionLagStatus() {
3233                 return $this->getTransactionLagStatus() ?: $this->getApproximateLagStatus();
3234         }
3235
3236         /**
3237          * Get the replica DB lag when the current transaction started
3238          *
3239          * This is useful when transactions might use snapshot isolation
3240          * (e.g. REPEATABLE-READ in innodb), so the "real" lag of that data
3241          * is this lag plus transaction duration. If they don't, it is still
3242          * safe to be pessimistic. This returns null if there is no transaction.
3243          *
3244          * @return array|null ('lag': seconds or false on error, 'since': UNIX timestamp of BEGIN)
3245          * @since 1.27
3246          */
3247         protected function getTransactionLagStatus() {
3248                 return $this->mTrxLevel
3249                         ? [ 'lag' => $this->mTrxReplicaLag, 'since' => $this->trxTimestamp() ]
3250                         : null;
3251         }
3252
3253         /**
3254          * Get a replica DB lag estimate for this server
3255          *
3256          * @return array ('lag': seconds or false on error, 'since': UNIX timestamp of estimate)
3257          * @since 1.27
3258          */
3259         protected function getApproximateLagStatus() {
3260                 return [
3261                         'lag'   => $this->getLBInfo( 'replica' ) ? $this->getLag() : 0,
3262                         'since' => microtime( true )
3263                 ];
3264         }
3265
3266         /**
3267          * Merge the result of getSessionLagStatus() for several DBs
3268          * using the most pessimistic values to estimate the lag of
3269          * any data derived from them in combination
3270          *
3271          * This is information is useful for caching modules
3272          *
3273          * @see WANObjectCache::set()
3274          * @see WANObjectCache::getWithSetCallback()
3275          *
3276          * @param IDatabase $db1
3277          * @param IDatabase $dbs,...
3278          * @return array Map of values:
3279          *   - lag: highest lag of any of the DBs or false on error (e.g. replication stopped)
3280          *   - since: oldest UNIX timestamp of any of the DB lag estimates
3281          *   - pending: whether any of the DBs have uncommitted changes
3282          * @since 1.27
3283          */
3284         public static function getCacheSetOptions( IDatabase $db1 ) {
3285                 $res = [ 'lag' => 0, 'since' => INF, 'pending' => false ];
3286                 foreach ( func_get_args() as $db ) {
3287                         /** @var IDatabase $db */
3288                         $status = $db->getSessionLagStatus();
3289                         if ( $status['lag'] === false ) {
3290                                 $res['lag'] = false;
3291                         } elseif ( $res['lag'] !== false ) {
3292                                 $res['lag'] = max( $res['lag'], $status['lag'] );
3293                         }
3294                         $res['since'] = min( $res['since'], $status['since'] );
3295                         $res['pending'] = $res['pending'] ?: $db->writesPending();
3296                 }
3297
3298                 return $res;
3299         }
3300
3301         public function getLag() {
3302                 return 0;
3303         }
3304
3305         public function maxListLen() {
3306                 return 0;
3307         }
3308
3309         public function encodeBlob( $b ) {
3310                 return $b;
3311         }
3312
3313         public function decodeBlob( $b ) {
3314                 if ( $b instanceof Blob ) {
3315                         $b = $b->fetch();
3316                 }
3317                 return $b;
3318         }
3319
3320         public function setSessionOptions( array $options ) {
3321         }
3322
3323         public function sourceFile(
3324                 $filename,
3325                 callable $lineCallback = null,
3326                 callable $resultCallback = null,
3327                 $fname = false,
3328                 callable $inputCallback = null
3329         ) {
3330                 MediaWiki\suppressWarnings();
3331                 $fp = fopen( $filename, 'r' );
3332                 MediaWiki\restoreWarnings();
3333
3334                 if ( false === $fp ) {
3335                         throw new RuntimeException( "Could not open \"{$filename}\".\n" );
3336                 }
3337
3338                 if ( !$fname ) {
3339                         $fname = __METHOD__ . "( $filename )";
3340                 }
3341
3342                 try {
3343                         $error = $this->sourceStream(
3344                                 $fp, $lineCallback, $resultCallback, $fname, $inputCallback );
3345                 } catch ( Exception $e ) {
3346                         fclose( $fp );
3347                         throw $e;
3348                 }
3349
3350                 fclose( $fp );
3351
3352                 return $error;
3353         }
3354
3355         public function setSchemaVars( $vars ) {
3356                 $this->mSchemaVars = $vars;
3357         }
3358
3359         public function sourceStream(
3360                 $fp,
3361                 callable $lineCallback = null,
3362                 callable $resultCallback = null,
3363                 $fname = __METHOD__,
3364                 callable $inputCallback = null
3365         ) {
3366                 $cmd = '';
3367
3368                 while ( !feof( $fp ) ) {
3369                         if ( $lineCallback ) {
3370                                 call_user_func( $lineCallback );
3371                         }
3372
3373                         $line = trim( fgets( $fp ) );
3374
3375                         if ( $line == '' ) {
3376                                 continue;
3377                         }
3378
3379                         if ( '-' == $line[0] && '-' == $line[1] ) {
3380                                 continue;
3381                         }
3382
3383                         if ( $cmd != '' ) {
3384                                 $cmd .= ' ';
3385                         }
3386
3387                         $done = $this->streamStatementEnd( $cmd, $line );
3388
3389                         $cmd .= "$line\n";
3390
3391                         if ( $done || feof( $fp ) ) {
3392                                 $cmd = $this->replaceVars( $cmd );
3393
3394                                 if ( !$inputCallback || call_user_func( $inputCallback, $cmd ) ) {
3395                                         $res = $this->query( $cmd, $fname );
3396
3397                                         if ( $resultCallback ) {
3398                                                 call_user_func( $resultCallback, $res, $this );
3399                                         }
3400
3401                                         if ( false === $res ) {
3402                                                 $err = $this->lastError();
3403
3404                                                 return "Query \"{$cmd}\" failed with error code \"$err\".\n";
3405                                         }
3406                                 }
3407                                 $cmd = '';
3408                         }
3409                 }
3410
3411                 return true;
3412         }
3413
3414         /**
3415          * Called by sourceStream() to check if we've reached a statement end
3416          *
3417          * @param string &$sql SQL assembled so far
3418          * @param string &$newLine New line about to be added to $sql
3419          * @return bool Whether $newLine contains end of the statement
3420          */
3421         public function streamStatementEnd( &$sql, &$newLine ) {
3422                 if ( $this->delimiter ) {
3423                         $prev = $newLine;
3424                         $newLine = preg_replace(
3425                                 '/' . preg_quote( $this->delimiter, '/' ) . '$/', '', $newLine );
3426                         if ( $newLine != $prev ) {
3427                                 return true;
3428                         }
3429                 }
3430
3431                 return false;
3432         }
3433
3434         /**
3435          * Database independent variable replacement. Replaces a set of variables
3436          * in an SQL statement with their contents as given by $this->getSchemaVars().
3437          *
3438          * Supports '{$var}' `{$var}` and / *$var* / (without the spaces) style variables.
3439          *
3440          * - '{$var}' should be used for text and is passed through the database's
3441          *   addQuotes method.
3442          * - `{$var}` should be used for identifiers (e.g. table and database names).
3443          *   It is passed through the database's addIdentifierQuotes method which
3444          *   can be overridden if the database uses something other than backticks.
3445          * - / *_* / or / *$wgDBprefix* / passes the name that follows through the
3446          *   database's tableName method.
3447          * - / *i* / passes the name that follows through the database's indexName method.
3448          * - In all other cases, / *$var* / is left unencoded. Except for table options,
3449          *   its use should be avoided. In 1.24 and older, string encoding was applied.
3450          *
3451          * @param string $ins SQL statement to replace variables in
3452          * @return string The new SQL statement with variables replaced
3453          */
3454         protected function replaceVars( $ins ) {
3455                 $vars = $this->getSchemaVars();
3456                 return preg_replace_callback(
3457                         '!
3458                                 /\* (\$wgDBprefix|[_i]) \*/ (\w*) | # 1-2. tableName, indexName
3459                                 \'\{\$ (\w+) }\'                  | # 3. addQuotes
3460                                 `\{\$ (\w+) }`                    | # 4. addIdentifierQuotes
3461                                 /\*\$ (\w+) \*/                     # 5. leave unencoded
3462                         !x',
3463                         function ( $m ) use ( $vars ) {
3464                                 // Note: Because of <https://bugs.php.net/bug.php?id=51881>,
3465                                 // check for both nonexistent keys *and* the empty string.
3466                                 if ( isset( $m[1] ) && $m[1] !== '' ) {
3467                                         if ( $m[1] === 'i' ) {
3468                                                 return $this->indexName( $m[2] );
3469                                         } else {
3470                                                 return $this->tableName( $m[2] );
3471                                         }
3472                                 } elseif ( isset( $m[3] ) && $m[3] !== '' && array_key_exists( $m[3], $vars ) ) {
3473                                         return $this->addQuotes( $vars[$m[3]] );
3474                                 } elseif ( isset( $m[4] ) && $m[4] !== '' && array_key_exists( $m[4], $vars ) ) {
3475                                         return $this->addIdentifierQuotes( $vars[$m[4]] );
3476                                 } elseif ( isset( $m[5] ) && $m[5] !== '' && array_key_exists( $m[5], $vars ) ) {
3477                                         return $vars[$m[5]];
3478                                 } else {
3479                                         return $m[0];
3480                                 }
3481                         },
3482                         $ins
3483                 );
3484         }
3485
3486         /**
3487          * Get schema variables. If none have been set via setSchemaVars(), then
3488          * use some defaults from the current object.
3489          *
3490          * @return array
3491          */
3492         protected function getSchemaVars() {
3493                 if ( $this->mSchemaVars ) {
3494                         return $this->mSchemaVars;
3495                 } else {
3496                         return $this->getDefaultSchemaVars();
3497                 }
3498         }
3499
3500         /**
3501          * Get schema variables to use if none have been set via setSchemaVars().
3502          *
3503          * Override this in derived classes to provide variables for tables.sql
3504          * and SQL patch files.
3505          *
3506          * @return array
3507          */
3508         protected function getDefaultSchemaVars() {
3509                 return [];
3510         }
3511
3512         public function lockIsFree( $lockName, $method ) {
3513                 return true;
3514         }
3515
3516         public function lock( $lockName, $method, $timeout = 5 ) {
3517                 $this->mNamedLocksHeld[$lockName] = 1;
3518
3519                 return true;
3520         }
3521
3522         public function unlock( $lockName, $method ) {
3523                 unset( $this->mNamedLocksHeld[$lockName] );
3524
3525                 return true;
3526         }
3527
3528         public function getScopedLockAndFlush( $lockKey, $fname, $timeout ) {
3529                 if ( $this->writesOrCallbacksPending() ) {
3530                         // This only flushes transactions to clear snapshots, not to write data
3531                         $fnames = implode( ', ', $this->pendingWriteAndCallbackCallers() );
3532                         throw new DBUnexpectedError(
3533                                 $this,
3534                                 "$fname: Cannot flush pre-lock snapshot because writes are pending ($fnames)."
3535                         );
3536                 }
3537
3538                 if ( !$this->lock( $lockKey, $fname, $timeout ) ) {
3539                         return null;
3540                 }
3541
3542                 $unlocker = new ScopedCallback( function () use ( $lockKey, $fname ) {
3543                         if ( $this->trxLevel() ) {
3544                                 // There is a good chance an exception was thrown, causing any early return
3545                                 // from the caller. Let any error handler get a chance to issue rollback().
3546                                 // If there isn't one, let the error bubble up and trigger server-side rollback.
3547                                 $this->onTransactionResolution(
3548                                         function () use ( $lockKey, $fname ) {
3549                                                 $this->unlock( $lockKey, $fname );
3550                                         },
3551                                         $fname
3552                                 );
3553                         } else {
3554                                 $this->unlock( $lockKey, $fname );
3555                         }
3556                 } );
3557
3558                 $this->commit( $fname, self::FLUSHING_INTERNAL );
3559
3560                 return $unlocker;
3561         }
3562
3563         public function namedLocksEnqueue() {
3564                 return false;
3565         }
3566
3567         public function tableLocksHaveTransactionScope() {
3568                 return true;
3569         }
3570
3571         final public function lockTables( array $read, array $write, $method ) {
3572                 if ( $this->writesOrCallbacksPending() ) {
3573                         throw new DBUnexpectedError( $this, "Transaction writes or callbacks still pending." );
3574                 }
3575
3576                 if ( $this->tableLocksHaveTransactionScope() ) {
3577                         $this->startAtomic( $method );
3578                 }
3579
3580                 return $this->doLockTables( $read, $write, $method );
3581         }
3582
3583         /**
3584          * Helper function for lockTables() that handles the actual table locking
3585          *
3586          * @param array $read Array of tables to lock for read access
3587          * @param array $write Array of tables to lock for write access
3588          * @param string $method Name of caller
3589          * @return true
3590          */
3591         protected function doLockTables( array $read, array $write, $method ) {
3592                 return true;
3593         }
3594
3595         final public function unlockTables( $method ) {
3596                 if ( $this->tableLocksHaveTransactionScope() ) {
3597                         $this->endAtomic( $method );
3598
3599                         return true; // locks released on COMMIT/ROLLBACK
3600                 }
3601
3602                 return $this->doUnlockTables( $method );
3603         }
3604
3605         /**
3606          * Helper function for unlockTables() that handles the actual table unlocking
3607          *
3608          * @param string $method Name of caller
3609          * @return true
3610          */
3611         protected function doUnlockTables( $method ) {
3612                 return true;
3613         }
3614
3615         /**
3616          * Delete a table
3617          * @param string $tableName
3618          * @param string $fName
3619          * @return bool|ResultWrapper
3620          * @since 1.18
3621          */
3622         public function dropTable( $tableName, $fName = __METHOD__ ) {
3623                 if ( !$this->tableExists( $tableName, $fName ) ) {
3624                         return false;
3625                 }
3626                 $sql = "DROP TABLE " . $this->tableName( $tableName ) . " CASCADE";
3627
3628                 return $this->query( $sql, $fName );
3629         }
3630
3631         public function getInfinity() {
3632                 return 'infinity';
3633         }
3634
3635         public function encodeExpiry( $expiry ) {
3636                 return ( $expiry == '' || $expiry == 'infinity' || $expiry == $this->getInfinity() )
3637                         ? $this->getInfinity()
3638                         : $this->timestamp( $expiry );
3639         }
3640
3641         public function decodeExpiry( $expiry, $format = TS_MW ) {
3642                 if ( $expiry == '' || $expiry == 'infinity' || $expiry == $this->getInfinity() ) {
3643                         return 'infinity';
3644                 }
3645
3646                 return ConvertibleTimestamp::convert( $format, $expiry );
3647         }
3648
3649         public function setBigSelects( $value = true ) {
3650                 // no-op
3651         }
3652
3653         public function isReadOnly() {
3654                 return ( $this->getReadOnlyReason() !== false );
3655         }
3656
3657         /**
3658          * @return string|bool Reason this DB is read-only or false if it is not
3659          */
3660         protected function getReadOnlyReason() {
3661                 $reason = $this->getLBInfo( 'readOnlyReason' );
3662
3663                 return is_string( $reason ) ? $reason : false;
3664         }
3665
3666         public function setTableAliases( array $aliases ) {
3667                 $this->tableAliases = $aliases;
3668         }
3669
3670         /**
3671          * @return bool Whether a DB user is required to access the DB
3672          * @since 1.28
3673          */
3674         protected function requiresDatabaseUser() {
3675                 return true;
3676         }
3677
3678         /**
3679          * Get the underlying binding handle, mConn
3680          *
3681          * Makes sure that mConn is set (disconnects and ping() failure can unset it).
3682          * This catches broken callers than catch and ignore disconnection exceptions.
3683          * Unlike checking isOpen(), this is safe to call inside of open().
3684          *
3685          * @return resource|object
3686          * @throws DBUnexpectedError
3687          * @since 1.26
3688          */
3689         protected function getBindingHandle() {
3690                 if ( !$this->mConn ) {
3691                         throw new DBUnexpectedError(
3692                                 $this,
3693                                 'DB connection was already closed or the connection dropped.'
3694                         );
3695                 }
3696
3697                 return $this->mConn;
3698         }
3699
3700         /**
3701          * @since 1.19
3702          * @return string
3703          */
3704         public function __toString() {
3705                 return (string)$this->mConn;
3706         }
3707
3708         /**
3709          * Make sure that copies do not share the same client binding handle
3710          * @throws DBConnectionError
3711          */
3712         public function __clone() {
3713                 $this->connLogger->warning(
3714                         "Cloning " . static::class . " is not recomended; forking connection:\n" .
3715                         ( new RuntimeException() )->getTraceAsString()
3716                 );
3717
3718                 if ( $this->isOpen() ) {
3719                         // Open a new connection resource without messing with the old one
3720                         $this->mOpened = false;
3721                         $this->mConn = false;
3722                         $this->mTrxEndCallbacks = []; // don't copy
3723                         $this->handleSessionLoss(); // no trx or locks anymore
3724                         $this->open( $this->mServer, $this->mUser, $this->mPassword, $this->mDBname );
3725                         $this->lastPing = microtime( true );
3726                 }
3727         }
3728
3729         /**
3730          * Called by serialize. Throw an exception when DB connection is serialized.
3731          * This causes problems on some database engines because the connection is
3732          * not restored on unserialize.
3733          */
3734         public function __sleep() {
3735                 throw new RuntimeException( 'Database serialization may cause problems, since ' .
3736                         'the connection is not restored on wakeup.' );
3737         }
3738
3739         /**
3740          * Run a few simple sanity checks and close dangling connections
3741          */
3742         public function __destruct() {
3743                 if ( $this->mTrxLevel && $this->mTrxDoneWrites ) {
3744                         trigger_error( "Uncommitted DB writes (transaction from {$this->mTrxFname})." );
3745                 }
3746
3747                 $danglingWriters = $this->pendingWriteAndCallbackCallers();
3748                 if ( $danglingWriters ) {
3749                         $fnames = implode( ', ', $danglingWriters );
3750                         trigger_error( "DB transaction writes or callbacks still pending ($fnames)." );
3751                 }
3752
3753                 if ( $this->mConn ) {
3754                         // Avoid connection leaks for sanity. Normally, resources close at script completion.
3755                         // The connection might already be closed in zend/hhvm by now, so suppress warnings.
3756                         \MediaWiki\suppressWarnings();
3757                         $this->closeConnection();
3758                         \MediaWiki\restoreWarnings();
3759                         $this->mConn = false;
3760                         $this->mOpened = false;
3761                 }
3762         }
3763 }
3764
3765 class_alias( Database::class, 'DatabaseBase' ); // b/c for old name
3766 class_alias( Database::class, 'Database' ); // b/c global alias