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                                 $msg = __METHOD__ . ": lost connection to {$this->getServer()}; reconnected";
 949                                 $this->connLogger->warning( $msg );
 950                                 $this->queryLogger->warning(
 951                                         "$msg:\n" . ( new RuntimeException() )->getTraceAsString() );
 952
 953                                 if ( !$recoverable ) {
 954                                         # Callers may catch the exception and continue to use the DB
 955                                         $this->reportQueryError( $lastError, $lastErrno, $sql, $fname );
 956                                 } else {
 957                                         # Should be safe to silently retry the query
 958                                         $ret = $this->doProfiledQuery( $sql, $commentedSql, $isNonTempWrite, $fname );
 959                                 }
 960                         } else {
 961                                 $msg = __METHOD__ . ": lost connection to {$this->getServer()} permanently";
 962                                 $this->connLogger->error( $msg );
 963                         }
 964                 }
 965
 966                 if ( false === $ret ) {
 967                         # Deadlocks cause the entire transaction to abort, not just the statement.
 968                         # https://dev.mysql.com/doc/refman/5.7/en/innodb-error-handling.html
 969                         # https://www.postgresql.org/docs/9.1/static/explicit-locking.html
 970                         if ( $this->wasDeadlock() ) {
 971                                 if ( $this->explicitTrxActive() || $priorWritesPending ) {
 972                                         $tempIgnore = false; // not recoverable
 973                                 }
 974                                 # Update state tracking to reflect transaction loss
 975                                 $this->handleSessionLoss();
 976                         }
 977
 978                         $this->reportQueryError(
 979                                 $this->lastError(), $this->lastErrno(), $sql, $fname, $tempIgnore );
 980                 }
 981
 982                 $res = $this->resultObject( $ret );
 983
 984                 return $res;
 985         }
 986
 987         /**
 988          * Helper method for query() that handles profiling and logging and sends
 989          * the query to doQuery()
 990          *
 991          * @param string $sql Original SQL query
 992          * @param string $commentedSql SQL query with debugging/trace comment
 993          * @param bool $isWrite Whether the query is a (non-temporary) write operation
 994          * @param string $fname Name of the calling function
 995          * @return bool|ResultWrapper True for a successful write query, ResultWrapper
 996          *     object for a successful read query, or false on failure
 997          */
 998         private function doProfiledQuery( $sql, $commentedSql, $isWrite, $fname ) {
 999                 $isMaster = !is_null( $this->getLBInfo( 'master' ) );
1000                 # generalizeSQL() will probably cut down the query to reasonable
1001                 # logging size most of the time. The substr is really just a sanity check.
1002                 if ( $isMaster ) {
1003                         $queryProf = 'query-m: ' . substr( self::generalizeSQL( $sql ), 0, 255 );
1004                 } else {
1005                         $queryProf = 'query: ' . substr( self::generalizeSQL( $sql ), 0, 255 );
1006                 }
1007
1008                 # Include query transaction state
1009                 $queryProf .= $this->mTrxShortId ? " [TRX#{$this->mTrxShortId}]" : "";
1010
1011                 $startTime = microtime( true );
1012                 if ( $this->profiler ) {
1013                         call_user_func( [ $this->profiler, 'profileIn' ], $queryProf );
1014                 }
1015                 $ret = $this->doQuery( $commentedSql );
1016                 if ( $this->profiler ) {
1017                         call_user_func( [ $this->profiler, 'profileOut' ], $queryProf );
1018                 }
1019                 $queryRuntime = max( microtime( true ) - $startTime, 0.0 );
1020
1021                 unset( $queryProfSection ); // profile out (if set)
1022
1023                 if ( $ret !== false ) {
1024                         $this->lastPing = $startTime;
1025                         if ( $isWrite && $this->mTrxLevel ) {
1026                                 $this->updateTrxWriteQueryTime( $sql, $queryRuntime, $this->affectedRows() );
1027                                 $this->mTrxWriteCallers[] = $fname;
1028                         }
1029                 }
1030
1031                 if ( $sql === self::PING_QUERY ) {
1032                         $this->mRTTEstimate = $queryRuntime;
1033                 }
1034
1035                 $this->trxProfiler->recordQueryCompletion(
1036                         $queryProf, $startTime, $isWrite, $this->affectedRows()
1037                 );
1038                 $this->queryLogger->debug( $sql, [
1039                         'method' => $fname,
1040                         'master' => $isMaster,
1041                         'runtime' => $queryRuntime,
1042                 ] );
1043
1044                 return $ret;
1045         }
1046
1047         /**
1048          * Update the estimated run-time of a query, not counting large row lock times
1049          *
1050          * LoadBalancer can be set to rollback transactions that will create huge replication
1051          * lag. It bases this estimate off of pendingWriteQueryDuration(). Certain simple
1052          * queries, like inserting a row can take a long time due to row locking. This method
1053          * uses some simple heuristics to discount those cases.
1054          *
1055          * @param string $sql A SQL write query
1056          * @param float $runtime Total runtime, including RTT
1057          * @param int $affected Affected row count
1058          */
1059         private function updateTrxWriteQueryTime( $sql, $runtime, $affected ) {
1060                 // Whether this is indicative of replica DB runtime (except for RBR or ws_repl)
1061                 $indicativeOfReplicaRuntime = true;
1062                 if ( $runtime > self::SLOW_WRITE_SEC ) {
1063                         $verb = $this->getQueryVerb( $sql );
1064                         // insert(), upsert(), replace() are fast unless bulky in size or blocked on locks
1065                         if ( $verb === 'INSERT' ) {
1066                                 $indicativeOfReplicaRuntime = $this->affectedRows() > self::SMALL_WRITE_ROWS;
1067                         } elseif ( $verb === 'REPLACE' ) {
1068                                 $indicativeOfReplicaRuntime = $this->affectedRows() > self::SMALL_WRITE_ROWS / 2;
1069                         }
1070                 }
1071
1072                 $this->mTrxWriteDuration += $runtime;
1073                 $this->mTrxWriteQueryCount += 1;
1074                 $this->mTrxWriteAffectedRows += $affected;
1075                 if ( $indicativeOfReplicaRuntime ) {
1076                         $this->mTrxWriteAdjDuration += $runtime;
1077                         $this->mTrxWriteAdjQueryCount += 1;
1078                 }
1079         }
1080
1081         /**
1082          * Determine whether or not it is safe to retry queries after a database
1083          * connection is lost
1084          *
1085          * @param string $sql SQL query
1086          * @param bool $priorWritesPending Whether there is a transaction open with
1087          *     possible write queries or transaction pre-commit/idle callbacks
1088          *     waiting on it to finish.
1089          * @return bool True if it is safe to retry the query, false otherwise
1090          */
1091         private function canRecoverFromDisconnect( $sql, $priorWritesPending ) {
1092                 # Transaction dropped; this can mean lost writes, or REPEATABLE-READ snapshots.
1093                 # Dropped connections also mean that named locks are automatically released.
1094                 # Only allow error suppression in autocommit mode or when the lost transaction
1095                 # didn't matter anyway (aside from DBO_TRX snapshot loss).
1096                 if ( $this->mNamedLocksHeld ) {
1097                         return false; // possible critical section violation
1098                 } elseif ( $sql === 'COMMIT' ) {
1099                         return !$priorWritesPending; // nothing written anyway? (T127428)
1100                 } elseif ( $sql === 'ROLLBACK' ) {
1101                         return true; // transaction lost...which is also what was requested :)
1102                 } elseif ( $this->explicitTrxActive() ) {
1103                         return false; // don't drop atomocity
1104                 } elseif ( $priorWritesPending ) {
1105                         return false; // prior writes lost from implicit transaction
1106                 }
1107
1108                 return true;
1109         }
1110
1111         /**
1112          * Clean things up after transaction loss due to disconnection
1113          *
1114          * @return null|Exception
1115          */
1116         private function handleSessionLoss() {
1117                 $this->mTrxLevel = 0;
1118                 $this->mTrxIdleCallbacks = []; // T67263
1119                 $this->mTrxPreCommitCallbacks = []; // T67263
1120                 $this->mSessionTempTables = [];
1121                 $this->mNamedLocksHeld = [];
1122                 try {
1123                         // Handle callbacks in mTrxEndCallbacks
1124                         $this->runOnTransactionIdleCallbacks( self::TRIGGER_ROLLBACK );
1125                         $this->runTransactionListenerCallbacks( self::TRIGGER_ROLLBACK );
1126                         return null;
1127                 } catch ( Exception $e ) {
1128                         // Already logged; move on...
1129                         return $e;
1130                 }
1131         }
1132
1133         /**
1134          * Checks whether the cause of the error is detected to be a timeout.
1135          *
1136          * It returns false by default, and not all engines support detecting this yet.
1137          * If this returns false, it will be treated as a generic query error.
1138          *
1139          * @param string $error Error text
1140          * @param int $errno Error number
1141          */
1142         protected function wasQueryTimeout( $error, $errno ) {
1143                 return false;
1144         }
1145
1146         public function reportQueryError( $error, $errno, $sql, $fname, $tempIgnore = false ) {
1147                 if ( $this->ignoreErrors() || $tempIgnore ) {
1148                         $this->queryLogger->debug( "SQL ERROR (ignored): $error\n" );
1149                 } else {
1150                         $sql1line = mb_substr( str_replace( "\n", "\\n", $sql ), 0, 5 * 1024 );
1151                         $this->queryLogger->error(
1152                                 "{fname}\t{db_server}\t{errno}\t{error}\t{sql1line}",
1153                                 $this->getLogContext( [
1154                                         'method' => __METHOD__,
1155                                         'errno' => $errno,
1156                                         'error' => $error,
1157                                         'sql1line' => $sql1line,
1158                                         'fname' => $fname,
1159                                 ] )
1160                         );
1161                         $this->queryLogger->debug( "SQL ERROR: " . $error . "\n" );
1162                         $wasQueryTimeout = $this->wasQueryTimeout( $error, $errno );
1163                         if ( $wasQueryTimeout ) {
1164                                 throw new DBQueryTimeoutError( $this, $error, $errno, $sql, $fname );
1165                         } else {
1166                                 throw new DBQueryError( $this, $error, $errno, $sql, $fname );
1167                         }
1168                 }
1169         }
1170
1171         public function freeResult( $res ) {
1172         }
1173
1174         public function selectField(
1175                 $table, $var, $cond = '', $fname = __METHOD__, $options = [], $join_conds = []
1176         ) {
1177                 if ( $var === '*' ) { // sanity
1178                         throw new DBUnexpectedError( $this, "Cannot use a * field: got '$var'" );
1179                 }
1180
1181                 if ( !is_array( $options ) ) {
1182                         $options = [ $options ];
1183                 }
1184
1185                 $options['LIMIT'] = 1;
1186
1187                 $res = $this->select( $table, $var, $cond, $fname, $options, $join_conds );
1188                 if ( $res === false || !$this->numRows( $res ) ) {
1189                         return false;
1190                 }
1191
1192                 $row = $this->fetchRow( $res );
1193
1194                 if ( $row !== false ) {
1195                         return reset( $row );
1196                 } else {
1197                         return false;
1198                 }
1199         }
1200
1201         public function selectFieldValues(
1202                 $table, $var, $cond = '', $fname = __METHOD__, $options = [], $join_conds = []
1203         ) {
1204                 if ( $var === '*' ) { // sanity
1205                         throw new DBUnexpectedError( $this, "Cannot use a * field" );
1206                 } elseif ( !is_string( $var ) ) { // sanity
1207                         throw new DBUnexpectedError( $this, "Cannot use an array of fields" );
1208                 }
1209
1210                 if ( !is_array( $options ) ) {
1211                         $options = [ $options ];
1212                 }
1213
1214                 $res = $this->select( $table, $var, $cond, $fname, $options, $join_conds );
1215                 if ( $res === false ) {
1216                         return false;
1217                 }
1218
1219                 $values = [];
1220                 foreach ( $res as $row ) {
1221                         $values[] = $row->$var;
1222                 }
1223
1224                 return $values;
1225         }
1226
1227         /**
1228          * Returns an optional USE INDEX clause to go after the table, and a
1229          * string to go at the end of the query.
1230          *
1231          * @param array $options Associative array of options to be turned into
1232          *   an SQL query, valid keys are listed in the function.
1233          * @return array
1234          * @see Database::select()
1235          */
1236         protected function makeSelectOptions( $options ) {
1237                 $preLimitTail = $postLimitTail = '';
1238                 $startOpts = '';
1239
1240                 $noKeyOptions = [];
1241
1242                 foreach ( $options as $key => $option ) {
1243                         if ( is_numeric( $key ) ) {
1244                                 $noKeyOptions[$option] = true;
1245                         }
1246                 }
1247
1248                 $preLimitTail .= $this->makeGroupByWithHaving( $options );
1249
1250                 $preLimitTail .= $this->makeOrderBy( $options );
1251
1252                 if ( isset( $noKeyOptions['FOR UPDATE'] ) ) {
1253                         $postLimitTail .= ' FOR UPDATE';
1254                 }
1255
1256                 if ( isset( $noKeyOptions['LOCK IN SHARE MODE'] ) ) {
1257                         $postLimitTail .= ' LOCK IN SHARE MODE';
1258                 }
1259
1260                 if ( isset( $noKeyOptions['DISTINCT'] ) || isset( $noKeyOptions['DISTINCTROW'] ) ) {
1261                         $startOpts .= 'DISTINCT';
1262                 }
1263
1264                 # Various MySQL extensions
1265                 if ( isset( $noKeyOptions['STRAIGHT_JOIN'] ) ) {
1266                         $startOpts .= ' /*! STRAIGHT_JOIN */';
1267                 }
1268
1269                 if ( isset( $noKeyOptions['HIGH_PRIORITY'] ) ) {
1270                         $startOpts .= ' HIGH_PRIORITY';
1271                 }
1272
1273                 if ( isset( $noKeyOptions['SQL_BIG_RESULT'] ) ) {
1274                         $startOpts .= ' SQL_BIG_RESULT';
1275                 }
1276
1277                 if ( isset( $noKeyOptions['SQL_BUFFER_RESULT'] ) ) {
1278                         $startOpts .= ' SQL_BUFFER_RESULT';
1279                 }
1280
1281                 if ( isset( $noKeyOptions['SQL_SMALL_RESULT'] ) ) {
1282                         $startOpts .= ' SQL_SMALL_RESULT';
1283                 }
1284
1285                 if ( isset( $noKeyOptions['SQL_CALC_FOUND_ROWS'] ) ) {
1286                         $startOpts .= ' SQL_CALC_FOUND_ROWS';
1287                 }
1288
1289                 if ( isset( $noKeyOptions['SQL_CACHE'] ) ) {
1290                         $startOpts .= ' SQL_CACHE';
1291                 }
1292
1293                 if ( isset( $noKeyOptions['SQL_NO_CACHE'] ) ) {
1294                         $startOpts .= ' SQL_NO_CACHE';
1295                 }
1296
1297                 if ( isset( $options['USE INDEX'] ) && is_string( $options['USE INDEX'] ) ) {
1298                         $useIndex = $this->useIndexClause( $options['USE INDEX'] );
1299                 } else {
1300                         $useIndex = '';
1301                 }
1302                 if ( isset( $options['IGNORE INDEX'] ) && is_string( $options['IGNORE INDEX'] ) ) {
1303                         $ignoreIndex = $this->ignoreIndexClause( $options['IGNORE INDEX'] );
1304                 } else {
1305                         $ignoreIndex = '';
1306                 }
1307
1308                 return [ $startOpts, $useIndex, $preLimitTail, $postLimitTail, $ignoreIndex ];
1309         }
1310
1311         /**
1312          * Returns an optional GROUP BY with an optional HAVING
1313          *
1314          * @param array $options Associative array of options
1315          * @return string
1316          * @see Database::select()
1317          * @since 1.21
1318          */
1319         protected function makeGroupByWithHaving( $options ) {
1320                 $sql = '';
1321                 if ( isset( $options['GROUP BY'] ) ) {
1322                         $gb = is_array( $options['GROUP BY'] )
1323                                 ? implode( ',', $options['GROUP BY'] )
1324                                 : $options['GROUP BY'];
1325                         $sql .= ' GROUP BY ' . $gb;
1326                 }
1327                 if ( isset( $options['HAVING'] ) ) {
1328                         $having = is_array( $options['HAVING'] )
1329                                 ? $this->makeList( $options['HAVING'], self::LIST_AND )
1330                                 : $options['HAVING'];
1331                         $sql .= ' HAVING ' . $having;
1332                 }
1333
1334                 return $sql;
1335         }
1336
1337         /**
1338          * Returns an optional ORDER BY
1339          *
1340          * @param array $options Associative array of options
1341          * @return string
1342          * @see Database::select()
1343          * @since 1.21
1344          */
1345         protected function makeOrderBy( $options ) {
1346                 if ( isset( $options['ORDER BY'] ) ) {
1347                         $ob = is_array( $options['ORDER BY'] )
1348                                 ? implode( ',', $options['ORDER BY'] )
1349                                 : $options['ORDER BY'];
1350
1351                         return ' ORDER BY ' . $ob;
1352                 }
1353
1354                 return '';
1355         }
1356
1357         public function select( $table, $vars, $conds = '', $fname = __METHOD__,
1358                 $options = [], $join_conds = [] ) {
1359                 $sql = $this->selectSQLText( $table, $vars, $conds, $fname, $options, $join_conds );
1360
1361                 return $this->query( $sql, $fname );
1362         }
1363
1364         public function selectSQLText( $table, $vars, $conds = '', $fname = __METHOD__,
1365                 $options = [], $join_conds = []
1366         ) {
1367                 if ( is_array( $vars ) ) {
1368                         $vars = implode( ',', $this->fieldNamesWithAlias( $vars ) );
1369                 }
1370
1371                 $options = (array)$options;
1372                 $useIndexes = ( isset( $options['USE INDEX'] ) && is_array( $options['USE INDEX'] ) )
1373                         ? $options['USE INDEX']
1374                         : [];
1375                 $ignoreIndexes = (
1376                         isset( $options['IGNORE INDEX'] ) &&
1377                         is_array( $options['IGNORE INDEX'] )
1378                 )
1379                         ? $options['IGNORE INDEX']
1380                         : [];
1381
1382                 if ( is_array( $table ) ) {
1383                         $from = ' FROM ' .
1384                                 $this->tableNamesWithIndexClauseOrJOIN(
1385                                         $table, $useIndexes, $ignoreIndexes, $join_conds );
1386                 } elseif ( $table != '' ) {
1387                         if ( $table[0] == ' ' ) {
1388                                 $from = ' FROM ' . $table;
1389                         } else {
1390                                 $from = ' FROM ' .
1391                                         $this->tableNamesWithIndexClauseOrJOIN(
1392                                                 [ $table ], $useIndexes, $ignoreIndexes, [] );
1393                         }
1394                 } else {
1395                         $from = '';
1396                 }
1397
1398                 list( $startOpts, $useIndex, $preLimitTail, $postLimitTail, $ignoreIndex ) =
1399                         $this->makeSelectOptions( $options );
1400
1401                 if ( !empty( $conds ) ) {
1402                         if ( is_array( $conds ) ) {
1403                                 $conds = $this->makeList( $conds, self::LIST_AND );
1404                         }
1405                         $sql = "SELECT $startOpts $vars $from $useIndex $ignoreIndex " .
1406                                 "WHERE $conds $preLimitTail";
1407                 } else {
1408                         $sql = "SELECT $startOpts $vars $from $useIndex $ignoreIndex $preLimitTail";
1409                 }
1410
1411                 if ( isset( $options['LIMIT'] ) ) {
1412                         $sql = $this->limitResult( $sql, $options['LIMIT'],
1413                                 isset( $options['OFFSET'] ) ? $options['OFFSET'] : false );
1414                 }
1415                 $sql = "$sql $postLimitTail";
1416
1417                 if ( isset( $options['EXPLAIN'] ) ) {
1418                         $sql = 'EXPLAIN ' . $sql;
1419                 }
1420
1421                 return $sql;
1422         }
1423
1424         public function selectRow( $table, $vars, $conds, $fname = __METHOD__,
1425                 $options = [], $join_conds = []
1426         ) {
1427                 $options = (array)$options;
1428                 $options['LIMIT'] = 1;
1429                 $res = $this->select( $table, $vars, $conds, $fname, $options, $join_conds );
1430
1431                 if ( $res === false ) {
1432                         return false;
1433                 }
1434
1435                 if ( !$this->numRows( $res ) ) {
1436                         return false;
1437                 }
1438
1439                 $obj = $this->fetchObject( $res );
1440
1441                 return $obj;
1442         }
1443
1444         public function estimateRowCount(
1445                 $table, $vars = '*', $conds = '', $fname = __METHOD__, $options = []
1446         ) {
1447                 $rows = 0;
1448                 $res = $this->select( $table, [ 'rowcount' => 'COUNT(*)' ], $conds, $fname, $options );
1449
1450                 if ( $res ) {
1451                         $row = $this->fetchRow( $res );
1452                         $rows = ( isset( $row['rowcount'] ) ) ? (int)$row['rowcount'] : 0;
1453                 }
1454
1455                 return $rows;
1456         }
1457
1458         public function selectRowCount(
1459                 $tables, $vars = '*', $conds = '', $fname = __METHOD__, $options = [], $join_conds = []
1460         ) {
1461                 $rows = 0;
1462                 $sql = $this->selectSQLText( $tables, '1', $conds, $fname, $options, $join_conds );
1463                 // The identifier quotes is primarily for MSSQL.
1464                 $rowCountCol = $this->addIdentifierQuotes( "rowcount" );
1465                 $tableName = $this->addIdentifierQuotes( "tmp_count" );
1466                 $res = $this->query( "SELECT COUNT(*) AS $rowCountCol FROM ($sql) $tableName", $fname );
1467
1468                 if ( $res ) {
1469                         $row = $this->fetchRow( $res );
1470                         $rows = ( isset( $row['rowcount'] ) ) ? (int)$row['rowcount'] : 0;
1471                 }
1472
1473                 return $rows;
1474         }
1475
1476         /**
1477          * Removes most variables from an SQL query and replaces them with X or N for numbers.
1478          * It's only slightly flawed. Don't use for anything important.
1479          *
1480          * @param string $sql A SQL Query
1481          *
1482          * @return string
1483          */
1484         protected static function generalizeSQL( $sql ) {
1485                 # This does the same as the regexp below would do, but in such a way
1486                 # as to avoid crashing php on some large strings.
1487                 # $sql = preg_replace( "/'([^\\\\']|\\\\.)*'|\"([^\\\\\"]|\\\\.)*\"/", "'X'", $sql );
1488
1489                 $sql = str_replace( "\\\\", '', $sql );
1490                 $sql = str_replace( "\\'", '', $sql );
1491                 $sql = str_replace( "\\\"", '', $sql );
1492                 $sql = preg_replace( "/'.*'/s", "'X'", $sql );
1493                 $sql = preg_replace( '/".*"/s', "'X'", $sql );
1494
1495                 # All newlines, tabs, etc replaced by single space
1496                 $sql = preg_replace( '/\s+/', ' ', $sql );
1497
1498                 # All numbers => N,
1499                 # except the ones surrounded by characters, e.g. l10n
1500                 $sql = preg_replace( '/-?\d+(,-?\d+)+/s', 'N,...,N', $sql );
1501                 $sql = preg_replace( '/(?<![a-zA-Z])-?\d+(?![a-zA-Z])/s', 'N', $sql );
1502
1503                 return $sql;
1504         }
1505
1506         public function fieldExists( $table, $field, $fname = __METHOD__ ) {
1507                 $info = $this->fieldInfo( $table, $field );
1508
1509                 return (bool)$info;
1510         }
1511
1512         public function indexExists( $table, $index, $fname = __METHOD__ ) {
1513                 if ( !$this->tableExists( $table ) ) {
1514                         return null;
1515                 }
1516
1517                 $info = $this->indexInfo( $table, $index, $fname );
1518                 if ( is_null( $info ) ) {
1519                         return null;
1520                 } else {
1521                         return $info !== false;
1522                 }
1523         }
1524
1525         public function tableExists( $table, $fname = __METHOD__ ) {
1526                 $tableRaw = $this->tableName( $table, 'raw' );
1527                 if ( isset( $this->mSessionTempTables[$tableRaw] ) ) {
1528                         return true; // already known to exist
1529                 }
1530
1531                 $table = $this->tableName( $table );
1532                 $ignoreErrors = true;
1533                 $res = $this->query( "SELECT 1 FROM $table LIMIT 1", $fname, $ignoreErrors );
1534
1535                 return (bool)$res;
1536         }
1537
1538         public function indexUnique( $table, $index ) {
1539                 $indexInfo = $this->indexInfo( $table, $index );
1540
1541                 if ( !$indexInfo ) {
1542                         return null;
1543                 }
1544
1545                 return !$indexInfo[0]->Non_unique;
1546         }
1547
1548         /**
1549          * Helper for Database::insert().
1550          *
1551          * @param array $options
1552          * @return string
1553          */
1554         protected function makeInsertOptions( $options ) {
1555                 return implode( ' ', $options );
1556         }
1557
1558         public function insert( $table, $a, $fname = __METHOD__, $options = [] ) {
1559                 # No rows to insert, easy just return now
1560                 if ( !count( $a ) ) {
1561                         return true;
1562                 }
1563
1564                 $table = $this->tableName( $table );
1565
1566                 if ( !is_array( $options ) ) {
1567                         $options = [ $options ];
1568                 }
1569
1570                 $fh = null;
1571                 if ( isset( $options['fileHandle'] ) ) {
1572                         $fh = $options['fileHandle'];
1573                 }
1574                 $options = $this->makeInsertOptions( $options );
1575
1576                 if ( isset( $a[0] ) && is_array( $a[0] ) ) {
1577                         $multi = true;
1578                         $keys = array_keys( $a[0] );
1579                 } else {
1580                         $multi = false;
1581                         $keys = array_keys( $a );
1582                 }
1583
1584                 $sql = 'INSERT ' . $options .
1585                         " INTO $table (" . implode( ',', $keys ) . ') VALUES ';
1586
1587                 if ( $multi ) {
1588                         $first = true;
1589                         foreach ( $a as $row ) {
1590                                 if ( $first ) {
1591                                         $first = false;
1592                                 } else {
1593                                         $sql .= ',';
1594                                 }
1595                                 $sql .= '(' . $this->makeList( $row ) . ')';
1596                         }
1597                 } else {
1598                         $sql .= '(' . $this->makeList( $a ) . ')';
1599                 }
1600
1601                 if ( $fh !== null && false === fwrite( $fh, $sql ) ) {
1602                         return false;
1603                 } elseif ( $fh !== null ) {
1604                         return true;
1605                 }
1606
1607                 return (bool)$this->query( $sql, $fname );
1608         }
1609
1610         /**
1611          * Make UPDATE options array for Database::makeUpdateOptions
1612          *
1613          * @param array $options
1614          * @return array
1615          */
1616         protected function makeUpdateOptionsArray( $options ) {
1617                 if ( !is_array( $options ) ) {
1618                         $options = [ $options ];
1619                 }
1620
1621                 $opts = [];
1622
1623                 if ( in_array( 'IGNORE', $options ) ) {
1624                         $opts[] = 'IGNORE';
1625                 }
1626
1627                 return $opts;
1628         }
1629
1630         /**
1631          * Make UPDATE options for the Database::update function
1632          *
1633          * @param array $options The options passed to Database::update
1634          * @return string
1635          */
1636         protected function makeUpdateOptions( $options ) {
1637                 $opts = $this->makeUpdateOptionsArray( $options );
1638
1639                 return implode( ' ', $opts );
1640         }
1641
1642         public function update( $table, $values, $conds, $fname = __METHOD__, $options = [] ) {
1643                 $table = $this->tableName( $table );
1644                 $opts = $this->makeUpdateOptions( $options );
1645                 $sql = "UPDATE $opts $table SET " . $this->makeList( $values, self::LIST_SET );
1646
1647                 if ( $conds !== [] && $conds !== '*' ) {
1648                         $sql .= " WHERE " . $this->makeList( $conds, self::LIST_AND );
1649                 }
1650
1651                 return (bool)$this->query( $sql, $fname );
1652         }
1653
1654         public function makeList( $a, $mode = self::LIST_COMMA ) {
1655                 if ( !is_array( $a ) ) {
1656                         throw new DBUnexpectedError( $this, __METHOD__ . ' called with incorrect parameters' );
1657                 }
1658
1659                 $first = true;
1660                 $list = '';
1661
1662                 foreach ( $a as $field => $value ) {
1663                         if ( !$first ) {
1664                                 if ( $mode == self::LIST_AND ) {
1665                                         $list .= ' AND ';
1666                                 } elseif ( $mode == self::LIST_OR ) {
1667                                         $list .= ' OR ';
1668                                 } else {
1669                                         $list .= ',';
1670                                 }
1671                         } else {
1672                                 $first = false;
1673                         }
1674
1675                         if ( ( $mode == self::LIST_AND || $mode == self::LIST_OR ) && is_numeric( $field ) ) {
1676                                 $list .= "($value)";
1677                         } elseif ( $mode == self::LIST_SET && is_numeric( $field ) ) {
1678                                 $list .= "$value";
1679                         } elseif (
1680                                 ( $mode == self::LIST_AND || $mode == self::LIST_OR ) && is_array( $value )
1681                         ) {
1682                                 // Remove null from array to be handled separately if found
1683                                 $includeNull = false;
1684                                 foreach ( array_keys( $value, null, true ) as $nullKey ) {
1685                                         $includeNull = true;
1686                                         unset( $value[$nullKey] );
1687                                 }
1688                                 if ( count( $value ) == 0 && !$includeNull ) {
1689                                         throw new InvalidArgumentException(
1690                                                 __METHOD__ . ": empty input for field $field" );
1691                                 } elseif ( count( $value ) == 0 ) {
1692                                         // only check if $field is null
1693                                         $list .= "$field IS NULL";
1694                                 } else {
1695                                         // IN clause contains at least one valid element
1696                                         if ( $includeNull ) {
1697                                                 // Group subconditions to ensure correct precedence
1698                                                 $list .= '(';
1699                                         }
1700                                         if ( count( $value ) == 1 ) {
1701                                                 // Special-case single values, as IN isn't terribly efficient
1702                                                 // Don't necessarily assume the single key is 0; we don't
1703                                                 // enforce linear numeric ordering on other arrays here.
1704                                                 $value = array_values( $value )[0];
1705                                                 $list .= $field . " = " . $this->addQuotes( $value );
1706                                         } else {
1707                                                 $list .= $field . " IN (" . $this->makeList( $value ) . ") ";
1708                                         }
1709                                         // if null present in array, append IS NULL
1710                                         if ( $includeNull ) {
1711                                                 $list .= " OR $field IS NULL)";
1712                                         }
1713                                 }
1714                         } elseif ( $value === null ) {
1715                                 if ( $mode == self::LIST_AND || $mode == self::LIST_OR ) {
1716                                         $list .= "$field IS ";
1717                                 } elseif ( $mode == self::LIST_SET ) {
1718                                         $list .= "$field = ";
1719                                 }
1720                                 $list .= 'NULL';
1721                         } else {
1722                                 if (
1723                                         $mode == self::LIST_AND || $mode == self::LIST_OR || $mode == self::LIST_SET
1724                                 ) {
1725                                         $list .= "$field = ";
1726                                 }
1727                                 $list .= $mode == self::LIST_NAMES ? $value : $this->addQuotes( $value );
1728                         }
1729                 }
1730
1731                 return $list;
1732         }
1733
1734         public function makeWhereFrom2d( $data, $baseKey, $subKey ) {
1735                 $conds = [];
1736
1737                 foreach ( $data as $base => $sub ) {
1738                         if ( count( $sub ) ) {
1739                                 $conds[] = $this->makeList(
1740                                         [ $baseKey => $base, $subKey => array_keys( $sub ) ],
1741                                         self::LIST_AND );
1742                         }
1743                 }
1744
1745                 if ( $conds ) {
1746                         return $this->makeList( $conds, self::LIST_OR );
1747                 } else {
1748                         // Nothing to search for...
1749                         return false;
1750                 }
1751         }
1752
1753         public function aggregateValue( $valuedata, $valuename = 'value' ) {
1754                 return $valuename;
1755         }
1756
1757         public function bitNot( $field ) {
1758                 return "(~$field)";
1759         }
1760
1761         public function bitAnd( $fieldLeft, $fieldRight ) {
1762                 return "($fieldLeft & $fieldRight)";
1763         }
1764
1765         public function bitOr( $fieldLeft, $fieldRight ) {
1766                 return "($fieldLeft | $fieldRight)";
1767         }
1768
1769         public function buildConcat( $stringList ) {
1770                 return 'CONCAT(' . implode( ',', $stringList ) . ')';
1771         }
1772
1773         public function buildGroupConcatField(
1774                 $delim, $table, $field, $conds = '', $join_conds = []
1775         ) {
1776                 $fld = "GROUP_CONCAT($field SEPARATOR " . $this->addQuotes( $delim ) . ')';
1777
1778                 return '(' . $this->selectSQLText( $table, $fld, $conds, null, [], $join_conds ) . ')';
1779         }
1780
1781         public function buildStringCast( $field ) {
1782                 return $field;
1783         }
1784
1785         public function databasesAreIndependent() {
1786                 return false;
1787         }
1788
1789         public function selectDB( $db ) {
1790                 # Stub. Shouldn't cause serious problems if it's not overridden, but
1791                 # if your database engine supports a concept similar to MySQL's
1792                 # databases you may as well.
1793                 $this->mDBname = $db;
1794
1795                 return true;
1796         }
1797
1798         public function getDBname() {
1799                 return $this->mDBname;
1800         }
1801
1802         public function getServer() {
1803                 return $this->mServer;
1804         }
1805
1806         public function tableName( $name, $format = 'quoted' ) {
1807                 # Skip the entire process when we have a string quoted on both ends.
1808                 # Note that we check the end so that we will still quote any use of
1809                 # use of `database`.table. But won't break things if someone wants
1810                 # to query a database table with a dot in the name.
1811                 if ( $this->isQuotedIdentifier( $name ) ) {
1812                         return $name;
1813                 }
1814
1815                 # Lets test for any bits of text that should never show up in a table
1816                 # name. Basically anything like JOIN or ON which are actually part of
1817                 # SQL queries, but may end up inside of the table value to combine
1818                 # sql. Such as how the API is doing.
1819                 # Note that we use a whitespace test rather than a \b test to avoid
1820                 # any remote case where a word like on may be inside of a table name
1821                 # surrounded by symbols which may be considered word breaks.
1822                 if ( preg_match( '/(^|\s)(DISTINCT|JOIN|ON|AS)(\s|$)/i', $name ) !== 0 ) {
1823                         return $name;
1824                 }
1825
1826                 # Split database and table into proper variables.
1827                 list( $database, $schema, $prefix, $table ) = $this->qualifiedTableComponents( $name );
1828
1829                 # Quote $table and apply the prefix if not quoted.
1830                 # $tableName might be empty if this is called from Database::replaceVars()
1831                 $tableName = "{$prefix}{$table}";
1832                 if ( $format === 'quoted'
1833                         && !$this->isQuotedIdentifier( $tableName )
1834                         && $tableName !== ''
1835                 ) {
1836                         $tableName = $this->addIdentifierQuotes( $tableName );
1837                 }
1838
1839                 # Quote $schema and $database and merge them with the table name if needed
1840                 $tableName = $this->prependDatabaseOrSchema( $schema, $tableName, $format );
1841                 $tableName = $this->prependDatabaseOrSchema( $database, $tableName, $format );
1842
1843                 return $tableName;
1844         }
1845
1846         /**
1847          * Get the table components needed for a query given the currently selected database
1848          *
1849          * @param string $name Table name in the form of db.schema.table, db.table, or table
1850          * @return array (DB name or "" for default, schema name, table prefix, table name)
1851          */
1852         protected function qualifiedTableComponents( $name ) {
1853                 # We reverse the explode so that database.table and table both output the correct table.
1854                 $dbDetails = explode( '.', $name, 3 );
1855                 if ( count( $dbDetails ) == 3 ) {
1856                         list( $database, $schema, $table ) = $dbDetails;
1857                         # We don't want any prefix added in this case
1858                         $prefix = '';
1859                 } elseif ( count( $dbDetails ) == 2 ) {
1860                         list( $database, $table ) = $dbDetails;
1861                         # We don't want any prefix added in this case
1862                         $prefix = '';
1863                         # In dbs that support it, $database may actually be the schema
1864                         # but that doesn't affect any of the functionality here
1865                         $schema = '';
1866                 } else {
1867                         list( $table ) = $dbDetails;
1868                         if ( isset( $this->tableAliases[$table] ) ) {
1869                                 $database = $this->tableAliases[$table]['dbname'];
1870                                 $schema = is_string( $this->tableAliases[$table]['schema'] )
1871                                         ? $this->tableAliases[$table]['schema']
1872                                         : $this->mSchema;
1873                                 $prefix = is_string( $this->tableAliases[$table]['prefix'] )
1874                                         ? $this->tableAliases[$table]['prefix']
1875                                         : $this->mTablePrefix;
1876                         } else {
1877                                 $database = '';
1878                                 $schema = $this->mSchema; # Default schema
1879                                 $prefix = $this->mTablePrefix; # Default prefix
1880                         }
1881                 }
1882
1883                 return [ $database, $schema, $prefix, $table ];
1884         }
1885
1886         /**
1887          * @param string|null $namespace Database or schema
1888          * @param string $relation Name of table, view, sequence, etc...
1889          * @param string $format One of (raw, quoted)
1890          * @return string Relation name with quoted and merged $namespace as needed
1891          */
1892         private function prependDatabaseOrSchema( $namespace, $relation, $format ) {
1893                 if ( strlen( $namespace ) ) {
1894                         if ( $format === 'quoted' && !$this->isQuotedIdentifier( $namespace ) ) {
1895                                 $namespace = $this->addIdentifierQuotes( $namespace );
1896                         }
1897                         $relation = $namespace . '.' . $relation;
1898                 }
1899
1900                 return $relation;
1901         }
1902
1903         public function tableNames() {
1904                 $inArray = func_get_args();
1905                 $retVal = [];
1906
1907                 foreach ( $inArray as $name ) {
1908                         $retVal[$name] = $this->tableName( $name );
1909                 }
1910
1911                 return $retVal;
1912         }
1913
1914         public function tableNamesN() {
1915                 $inArray = func_get_args();
1916                 $retVal = [];
1917
1918                 foreach ( $inArray as $name ) {
1919                         $retVal[] = $this->tableName( $name );
1920                 }
1921
1922                 return $retVal;
1923         }
1924
1925         /**
1926          * Get an aliased table name
1927          * e.g. tableName AS newTableName
1928          *
1929          * @param string $name Table name, see tableName()
1930          * @param string|bool $alias Alias (optional)
1931          * @return string SQL name for aliased table. Will not alias a table to its own name
1932          */
1933         protected function tableNameWithAlias( $name, $alias = false ) {
1934                 if ( !$alias || $alias == $name ) {
1935                         return $this->tableName( $name );
1936                 } else {
1937                         return $this->tableName( $name ) . ' ' . $this->addIdentifierQuotes( $alias );
1938                 }
1939         }
1940
1941         /**
1942          * Gets an array of aliased table names
1943          *
1944          * @param array $tables [ [alias] => table ]
1945          * @return string[] See tableNameWithAlias()
1946          */
1947         protected function tableNamesWithAlias( $tables ) {
1948                 $retval = [];
1949                 foreach ( $tables as $alias => $table ) {
1950                         if ( is_numeric( $alias ) ) {
1951                                 $alias = $table;
1952                         }
1953                         $retval[] = $this->tableNameWithAlias( $table, $alias );
1954                 }
1955
1956                 return $retval;
1957         }
1958
1959         /**
1960          * Get an aliased field name
1961          * e.g. fieldName AS newFieldName
1962          *
1963          * @param string $name Field name
1964          * @param string|bool $alias Alias (optional)
1965          * @return string SQL name for aliased field. Will not alias a field to its own name
1966          */
1967         protected function fieldNameWithAlias( $name, $alias = false ) {
1968                 if ( !$alias || (string)$alias === (string)$name ) {
1969                         return $name;
1970                 } else {
1971                         return $name . ' AS ' . $this->addIdentifierQuotes( $alias ); // PostgreSQL needs AS
1972                 }
1973         }
1974
1975         /**
1976          * Gets an array of aliased field names
1977          *
1978          * @param array $fields [ [alias] => field ]
1979          * @return string[] See fieldNameWithAlias()
1980          */
1981         protected function fieldNamesWithAlias( $fields ) {
1982                 $retval = [];
1983                 foreach ( $fields as $alias => $field ) {
1984                         if ( is_numeric( $alias ) ) {
1985                                 $alias = $field;
1986                         }
1987                         $retval[] = $this->fieldNameWithAlias( $field, $alias );
1988                 }
1989
1990                 return $retval;
1991         }
1992
1993         /**
1994          * Get the aliased table name clause for a FROM clause
1995          * which might have a JOIN and/or USE INDEX or IGNORE INDEX clause
1996          *
1997          * @param array $tables ( [alias] => table )
1998          * @param array $use_index Same as for select()
1999          * @param array $ignore_index Same as for select()
2000          * @param array $join_conds Same as for select()
2001          * @return string
2002          */
2003         protected function tableNamesWithIndexClauseOrJOIN(
2004                 $tables, $use_index = [], $ignore_index = [], $join_conds = []
2005         ) {
2006                 $ret = [];
2007                 $retJOIN = [];
2008                 $use_index = (array)$use_index;
2009                 $ignore_index = (array)$ignore_index;
2010                 $join_conds = (array)$join_conds;
2011
2012                 foreach ( $tables as $alias => $table ) {
2013                         if ( !is_string( $alias ) ) {
2014                                 // No alias? Set it equal to the table name
2015                                 $alias = $table;
2016                         }
2017                         // Is there a JOIN clause for this table?
2018                         if ( isset( $join_conds[$alias] ) ) {
2019                                 list( $joinType, $conds ) = $join_conds[$alias];
2020                                 $tableClause = $joinType;
2021                                 $tableClause .= ' ' . $this->tableNameWithAlias( $table, $alias );
2022                                 if ( isset( $use_index[$alias] ) ) { // has USE INDEX?
2023                                         $use = $this->useIndexClause( implode( ',', (array)$use_index[$alias] ) );
2024                                         if ( $use != '' ) {
2025                                                 $tableClause .= ' ' . $use;
2026                                         }
2027                                 }
2028                                 if ( isset( $ignore_index[$alias] ) ) { // has IGNORE INDEX?
2029                                         $ignore = $this->ignoreIndexClause(
2030                                                 implode( ',', (array)$ignore_index[$alias] ) );
2031                                         if ( $ignore != '' ) {
2032                                                 $tableClause .= ' ' . $ignore;
2033                                         }
2034                                 }
2035                                 $on = $this->makeList( (array)$conds, self::LIST_AND );
2036                                 if ( $on != '' ) {
2037                                         $tableClause .= ' ON (' . $on . ')';
2038                                 }
2039
2040                                 $retJOIN[] = $tableClause;
2041                         } elseif ( isset( $use_index[$alias] ) ) {
2042                                 // Is there an INDEX clause for this table?
2043                                 $tableClause = $this->tableNameWithAlias( $table, $alias );
2044                                 $tableClause .= ' ' . $this->useIndexClause(
2045                                                 implode( ',', (array)$use_index[$alias] )
2046                                         );
2047
2048                                 $ret[] = $tableClause;
2049                         } elseif ( isset( $ignore_index[$alias] ) ) {
2050                                 // Is there an INDEX clause for this table?
2051                                 $tableClause = $this->tableNameWithAlias( $table, $alias );
2052                                 $tableClause .= ' ' . $this->ignoreIndexClause(
2053                                                 implode( ',', (array)$ignore_index[$alias] )
2054                                         );
2055
2056                                 $ret[] = $tableClause;
2057                         } else {
2058                                 $tableClause = $this->tableNameWithAlias( $table, $alias );
2059
2060                                 $ret[] = $tableClause;
2061                         }
2062                 }
2063
2064                 // We can't separate explicit JOIN clauses with ',', use ' ' for those
2065                 $implicitJoins = !empty( $ret ) ? implode( ',', $ret ) : "";
2066                 $explicitJoins = !empty( $retJOIN ) ? implode( ' ', $retJOIN ) : "";
2067
2068                 // Compile our final table clause
2069                 return implode( ' ', [ $implicitJoins, $explicitJoins ] );
2070         }
2071
2072         /**
2073          * Allows for index remapping in queries where this is not consistent across DBMS
2074          *
2075          * @param string $index
2076          * @return string
2077          */
2078         protected function indexName( $index ) {
2079                 return $index;
2080         }
2081
2082         public function addQuotes( $s ) {
2083                 if ( $s instanceof Blob ) {
2084                         $s = $s->fetch();
2085                 }
2086                 if ( $s === null ) {
2087                         return 'NULL';
2088                 } elseif ( is_bool( $s ) ) {
2089                         return (int)$s;
2090                 } else {
2091                         # This will also quote numeric values. This should be harmless,
2092                         # and protects against weird problems that occur when they really
2093                         # _are_ strings such as article titles and string->number->string
2094                         # conversion is not 1:1.
2095                         return "'" . $this->strencode( $s ) . "'";
2096                 }
2097         }
2098
2099         /**
2100          * Quotes an identifier using `backticks` or "double quotes" depending on the database type.
2101          * MySQL uses `backticks` while basically everything else uses double quotes.
2102          * Since MySQL is the odd one out here the double quotes are our generic
2103          * and we implement backticks in DatabaseMysqlBase.
2104          *
2105          * @param string $s
2106          * @return string
2107          */
2108         public function addIdentifierQuotes( $s ) {
2109                 return '"' . str_replace( '"', '""', $s ) . '"';
2110         }
2111
2112         /**
2113          * Returns if the given identifier looks quoted or not according to
2114          * the database convention for quoting identifiers .
2115          *
2116          * @note Do not use this to determine if untrusted input is safe.
2117          *   A malicious user can trick this function.
2118          * @param string $name
2119          * @return bool
2120          */
2121         public function isQuotedIdentifier( $name ) {
2122                 return $name[0] == '"' && substr( $name, -1, 1 ) == '"';
2123         }
2124
2125         /**
2126          * @param string $s
2127          * @param string $escapeChar
2128          * @return string
2129          */
2130         protected function escapeLikeInternal( $s, $escapeChar = '`' ) {
2131                 return str_replace( [ $escapeChar, '%', '_' ],
2132                         [ "{$escapeChar}{$escapeChar}", "{$escapeChar}%", "{$escapeChar}_" ],
2133                         $s );
2134         }
2135
2136         public function buildLike() {
2137                 $params = func_get_args();
2138
2139                 if ( count( $params ) > 0 && is_array( $params[0] ) ) {
2140                         $params = $params[0];
2141                 }
2142
2143                 $s = '';
2144
2145                 // We use ` instead of \ as the default LIKE escape character, since addQuotes()
2146                 // may escape backslashes, creating problems of double escaping. The `
2147                 // character has good cross-DBMS compatibility, avoiding special operators
2148                 // in MS SQL like ^ and %
2149                 $escapeChar = '`';
2150
2151                 foreach ( $params as $value ) {
2152                         if ( $value instanceof LikeMatch ) {
2153                                 $s .= $value->toString();
2154                         } else {
2155                                 $s .= $this->escapeLikeInternal( $value, $escapeChar );
2156                         }
2157                 }
2158
2159                 return ' LIKE ' . $this->addQuotes( $s ) . ' ESCAPE ' . $this->addQuotes( $escapeChar ) . ' ';
2160         }
2161
2162         public function anyChar() {
2163                 return new LikeMatch( '_' );
2164         }
2165
2166         public function anyString() {
2167                 return new LikeMatch( '%' );
2168         }
2169
2170         public function nextSequenceValue( $seqName ) {
2171                 return null;
2172         }
2173
2174         /**
2175          * USE INDEX clause. Unlikely to be useful for anything but MySQL. This
2176          * is only needed because a) MySQL must be as efficient as possible due to
2177          * its use on Wikipedia, and b) MySQL 4.0 is kind of dumb sometimes about
2178          * which index to pick. Anyway, other databases might have different
2179          * indexes on a given table. So don't bother overriding this unless you're
2180          * MySQL.
2181          * @param string $index
2182          * @return string
2183          */
2184         public function useIndexClause( $index ) {
2185                 return '';
2186         }
2187
2188         /**
2189          * IGNORE INDEX clause. Unlikely to be useful for anything but MySQL. This
2190          * is only needed because a) MySQL must be as efficient as possible due to
2191          * its use on Wikipedia, and b) MySQL 4.0 is kind of dumb sometimes about
2192          * which index to pick. Anyway, other databases might have different
2193          * indexes on a given table. So don't bother overriding this unless you're
2194          * MySQL.
2195          * @param string $index
2196          * @return string
2197          */
2198         public function ignoreIndexClause( $index ) {
2199                 return '';
2200         }
2201
2202         public function replace( $table, $uniqueIndexes, $rows, $fname = __METHOD__ ) {
2203                 $quotedTable = $this->tableName( $table );
2204
2205                 if ( count( $rows ) == 0 ) {
2206                         return;
2207                 }
2208
2209                 # Single row case
2210                 if ( !is_array( reset( $rows ) ) ) {
2211                         $rows = [ $rows ];
2212                 }
2213
2214                 // @FXIME: this is not atomic, but a trx would break affectedRows()
2215                 foreach ( $rows as $row ) {
2216                         # Delete rows which collide
2217                         if ( $uniqueIndexes ) {
2218                                 $sql = "DELETE FROM $quotedTable WHERE ";
2219                                 $first = true;
2220                                 foreach ( $uniqueIndexes as $index ) {
2221                                         if ( $first ) {
2222                                                 $first = false;
2223                                                 $sql .= '( ';
2224                                         } else {
2225                                                 $sql .= ' ) OR ( ';
2226                                         }
2227                                         if ( is_array( $index ) ) {
2228                                                 $first2 = true;
2229                                                 foreach ( $index as $col ) {
2230                                                         if ( $first2 ) {
2231                                                                 $first2 = false;
2232                                                         } else {
2233                                                                 $sql .= ' AND ';
2234                                                         }
2235                                                         $sql .= $col . '=' . $this->addQuotes( $row[$col] );
2236                                                 }
2237                                         } else {
2238                                                 $sql .= $index . '=' . $this->addQuotes( $row[$index] );
2239                                         }
2240                                 }
2241                                 $sql .= ' )';
2242                                 $this->query( $sql, $fname );
2243                         }
2244
2245                         # Now insert the row
2246                         $this->insert( $table, $row, $fname );
2247                 }
2248         }
2249
2250         /**
2251          * REPLACE query wrapper for MySQL and SQLite, which have a native REPLACE
2252          * statement.
2253          *
2254          * @param string $table Table name
2255          * @param array|string $rows Row(s) to insert
2256          * @param string $fname Caller function name
2257          *
2258          * @return ResultWrapper
2259          */
2260         protected function nativeReplace( $table, $rows, $fname ) {
2261                 $table = $this->tableName( $table );
2262
2263                 # Single row case
2264                 if ( !is_array( reset( $rows ) ) ) {
2265                         $rows = [ $rows ];
2266                 }
2267
2268                 $sql = "REPLACE INTO $table (" . implode( ',', array_keys( $rows[0] ) ) . ') VALUES ';
2269                 $first = true;
2270
2271                 foreach ( $rows as $row ) {
2272                         if ( $first ) {
2273                                 $first = false;
2274                         } else {
2275                                 $sql .= ',';
2276                         }
2277
2278                         $sql .= '(' . $this->makeList( $row ) . ')';
2279                 }
2280
2281                 return $this->query( $sql, $fname );
2282         }
2283
2284         public function upsert( $table, array $rows, array $uniqueIndexes, array $set,
2285                 $fname = __METHOD__
2286         ) {
2287                 if ( !count( $rows ) ) {
2288                         return true; // nothing to do
2289                 }
2290
2291                 if ( !is_array( reset( $rows ) ) ) {
2292                         $rows = [ $rows ];
2293                 }
2294
2295                 if ( count( $uniqueIndexes ) ) {
2296                         $clauses = []; // list WHERE clauses that each identify a single row
2297                         foreach ( $rows as $row ) {
2298                                 foreach ( $uniqueIndexes as $index ) {
2299                                         $index = is_array( $index ) ? $index : [ $index ]; // columns
2300                                         $rowKey = []; // unique key to this row
2301                                         foreach ( $index as $column ) {
2302                                                 $rowKey[$column] = $row[$column];
2303                                         }
2304                                         $clauses[] = $this->makeList( $rowKey, self::LIST_AND );
2305                                 }
2306                         }
2307                         $where = [ $this->makeList( $clauses, self::LIST_OR ) ];
2308                 } else {
2309                         $where = false;
2310                 }
2311
2312                 $useTrx = !$this->mTrxLevel;
2313                 if ( $useTrx ) {
2314                         $this->begin( $fname, self::TRANSACTION_INTERNAL );
2315                 }
2316                 try {
2317                         # Update any existing conflicting row(s)
2318                         if ( $where !== false ) {
2319                                 $ok = $this->update( $table, $set, $where, $fname );
2320                         } else {
2321                                 $ok = true;
2322                         }
2323                         # Now insert any non-conflicting row(s)
2324                         $ok = $this->insert( $table, $rows, $fname, [ 'IGNORE' ] ) && $ok;
2325                 } catch ( Exception $e ) {
2326                         if ( $useTrx ) {
2327                                 $this->rollback( $fname, self::FLUSHING_INTERNAL );
2328                         }
2329                         throw $e;
2330                 }
2331                 if ( $useTrx ) {
2332                         $this->commit( $fname, self::FLUSHING_INTERNAL );
2333                 }
2334
2335                 return $ok;
2336         }
2337
2338         public function deleteJoin( $delTable, $joinTable, $delVar, $joinVar, $conds,
2339                 $fname = __METHOD__
2340         ) {
2341                 if ( !$conds ) {
2342                         throw new DBUnexpectedError( $this, __METHOD__ . ' called with empty $conds' );
2343                 }
2344
2345                 $delTable = $this->tableName( $delTable );
2346                 $joinTable = $this->tableName( $joinTable );
2347                 $sql = "DELETE FROM $delTable WHERE $delVar IN (SELECT $joinVar FROM $joinTable ";
2348                 if ( $conds != '*' ) {
2349                         $sql .= 'WHERE ' . $this->makeList( $conds, self::LIST_AND );
2350                 }
2351                 $sql .= ')';
2352
2353                 $this->query( $sql, $fname );
2354         }
2355
2356         public function textFieldSize( $table, $field ) {
2357                 $table = $this->tableName( $table );
2358                 $sql = "SHOW COLUMNS FROM $table LIKE \"$field\";";
2359                 $res = $this->query( $sql, __METHOD__ );
2360                 $row = $this->fetchObject( $res );
2361
2362                 $m = [];
2363
2364                 if ( preg_match( '/\((.*)\)/', $row->Type, $m ) ) {
2365                         $size = $m[1];
2366                 } else {
2367                         $size = -1;
2368                 }
2369
2370                 return $size;
2371         }
2372
2373         public function delete( $table, $conds, $fname = __METHOD__ ) {
2374                 if ( !$conds ) {
2375                         throw new DBUnexpectedError( $this, __METHOD__ . ' called with no conditions' );
2376                 }
2377
2378                 $table = $this->tableName( $table );
2379                 $sql = "DELETE FROM $table";
2380
2381                 if ( $conds != '*' ) {
2382                         if ( is_array( $conds ) ) {
2383                                 $conds = $this->makeList( $conds, self::LIST_AND );
2384                         }
2385                         $sql .= ' WHERE ' . $conds;
2386                 }
2387
2388                 return $this->query( $sql, $fname );
2389         }
2390
2391         public function insertSelect(
2392                 $destTable, $srcTable, $varMap, $conds,
2393                 $fname = __METHOD__, $insertOptions = [], $selectOptions = [], $selectJoinConds = []
2394         ) {
2395                 if ( $this->cliMode ) {
2396                         // For massive migrations with downtime, we don't want to select everything
2397                         // into memory and OOM, so do all this native on the server side if possible.
2398                         return $this->nativeInsertSelect(
2399                                 $destTable,
2400                                 $srcTable,
2401                                 $varMap,
2402                                 $conds,
2403                                 $fname,
2404                                 $insertOptions,
2405                                 $selectOptions,
2406                                 $selectJoinConds
2407                         );
2408                 }
2409
2410                 // For web requests, do a locking SELECT and then INSERT. This puts the SELECT burden
2411                 // on only the master (without needing row-based-replication). It also makes it easy to
2412                 // know how big the INSERT is going to be.
2413                 $fields = [];
2414                 foreach ( $varMap as $dstColumn => $sourceColumnOrSql ) {
2415                         $fields[] = $this->fieldNameWithAlias( $sourceColumnOrSql, $dstColumn );
2416                 }
2417                 $selectOptions[] = 'FOR UPDATE';
2418                 $res = $this->select(
2419                         $srcTable, implode( ',', $fields ), $conds, $fname, $selectOptions, $selectJoinConds
2420                 );
2421                 if ( !$res ) {
2422                         return false;
2423                 }
2424
2425                 $rows = [];
2426                 foreach ( $res as $row ) {
2427                         $rows[] = (array)$row;
2428                 }
2429
2430                 return $this->insert( $destTable, $rows, $fname, $insertOptions );
2431         }
2432
2433         /**
2434          * Native server-side implementation of insertSelect() for situations where
2435          * we don't want to select everything into memory
2436          *
2437          * @see IDatabase::insertSelect()
2438          * @param string $destTable
2439          * @param string|array $srcTable
2440          * @param array $varMap
2441          * @param array $conds
2442          * @param string $fname
2443          * @param array $insertOptions
2444          * @param array $selectOptions
2445          * @param array $selectJoinConds
2446          * @return bool
2447          */
2448         protected function nativeInsertSelect( $destTable, $srcTable, $varMap, $conds,
2449                 $fname = __METHOD__,
2450                 $insertOptions = [], $selectOptions = [], $selectJoinConds = []
2451         ) {
2452                 $destTable = $this->tableName( $destTable );
2453
2454                 if ( !is_array( $insertOptions ) ) {
2455                         $insertOptions = [ $insertOptions ];
2456                 }
2457
2458                 $insertOptions = $this->makeInsertOptions( $insertOptions );
2459
2460                 $selectSql = $this->selectSQLText(
2461                         $srcTable,
2462                         array_values( $varMap ),
2463                         $conds,
2464                         $fname,
2465                         $selectOptions,
2466                         $selectJoinConds
2467                 );
2468
2469                 $sql = "INSERT $insertOptions" .
2470                         " INTO $destTable (" . implode( ',', array_keys( $varMap ) ) . ') ' .
2471                         $selectSql;
2472
2473                 return $this->query( $sql, $fname );
2474         }
2475
2476         /**
2477          * Construct a LIMIT query with optional offset. This is used for query
2478          * pages. The SQL should be adjusted so that only the first $limit rows
2479          * are returned. If $offset is provided as well, then the first $offset
2480          * rows should be discarded, and the next $limit rows should be returned.
2481          * If the result of the query is not ordered, then the rows to be returned
2482          * are theoretically arbitrary.
2483          *
2484          * $sql is expected to be a SELECT, if that makes a difference.
2485          *
2486          * The version provided by default works in MySQL and SQLite. It will very
2487          * likely need to be overridden for most other DBMSes.
2488          *
2489          * @param string $sql SQL query we will append the limit too
2490          * @param int $limit The SQL limit
2491          * @param int|bool $offset The SQL offset (default false)
2492          * @throws DBUnexpectedError
2493          * @return string
2494          */
2495         public function limitResult( $sql, $limit, $offset = false ) {
2496                 if ( !is_numeric( $limit ) ) {
2497                         throw new DBUnexpectedError( $this,
2498                                 "Invalid non-numeric limit passed to limitResult()\n" );
2499                 }
2500
2501                 return "$sql LIMIT "
2502                 . ( ( is_numeric( $offset ) && $offset != 0 ) ? "{$offset}," : "" )
2503                 . "{$limit} ";
2504         }
2505
2506         public function unionSupportsOrderAndLimit() {
2507                 return true; // True for almost every DB supported
2508         }
2509
2510         public function unionQueries( $sqls, $all ) {
2511                 $glue = $all ? ') UNION ALL (' : ') UNION (';
2512
2513                 return '(' . implode( $glue, $sqls ) . ')';
2514         }
2515
2516         public function unionConditionPermutations(
2517                 $table, $vars, array $permute_conds, $extra_conds = '', $fname = __METHOD__,
2518                 $options = [], $join_conds = []
2519         ) {
2520                 // First, build the Cartesian product of $permute_conds
2521                 $conds = [ [] ];
2522                 foreach ( $permute_conds as $field => $values ) {
2523                         if ( !$values ) {
2524                                 // Skip empty $values
2525                                 continue;
2526                         }
2527                         $values = array_unique( $values ); // For sanity
2528                         $newConds = [];
2529                         foreach ( $conds as $cond ) {
2530                                 foreach ( $values as $value ) {
2531                                         $cond[$field] = $value;
2532                                         $newConds[] = $cond; // Arrays are by-value, not by-reference, so this works
2533                                 }
2534                         }
2535                         $conds = $newConds;
2536                 }
2537
2538                 $extra_conds = $extra_conds === '' ? [] : (array)$extra_conds;
2539
2540                 // If there's just one condition and no subordering, hand off to
2541                 // selectSQLText directly.
2542                 if ( count( $conds ) === 1 &&
2543                         ( !isset( $options['INNER ORDER BY'] ) || !$this->unionSupportsOrderAndLimit() )
2544                 ) {
2545                         return $this->selectSQLText(
2546                                 $table, $vars, $conds[0] + $extra_conds, $fname, $options, $join_conds
2547                         );
2548                 }
2549
2550                 // Otherwise, we need to pull out the order and limit to apply after
2551                 // the union. Then build the SQL queries for each set of conditions in
2552                 // $conds. Then union them together (using UNION ALL, because the
2553                 // product *should* already be distinct).
2554                 $orderBy = $this->makeOrderBy( $options );
2555                 $limit = isset( $options['LIMIT'] ) ? $options['LIMIT'] : null;
2556                 $offset = isset( $options['OFFSET'] ) ? $options['OFFSET'] : false;
2557                 $all = empty( $options['NOTALL'] ) && !in_array( 'NOTALL', $options );
2558                 if ( !$this->unionSupportsOrderAndLimit() ) {
2559                         unset( $options['ORDER BY'], $options['LIMIT'], $options['OFFSET'] );
2560                 } else {
2561                         if ( array_key_exists( 'INNER ORDER BY', $options ) ) {
2562                                 $options['ORDER BY'] = $options['INNER ORDER BY'];
2563                         }
2564                         if ( $limit !== null && is_numeric( $offset ) && $offset != 0 ) {
2565                                 // We need to increase the limit by the offset rather than
2566                                 // using the offset directly, otherwise it'll skip incorrectly
2567                                 // in the subqueries.
2568                                 $options['LIMIT'] = $limit + $offset;
2569                                 unset( $options['OFFSET'] );
2570                         }
2571                 }
2572
2573                 $sqls = [];
2574                 foreach ( $conds as $cond ) {
2575                         $sqls[] = $this->selectSQLText(
2576                                 $table, $vars, $cond + $extra_conds, $fname, $options, $join_conds
2577                         );
2578                 }
2579                 $sql = $this->unionQueries( $sqls, $all ) . $orderBy;
2580                 if ( $limit !== null ) {
2581                         $sql = $this->limitResult( $sql, $limit, $offset );
2582                 }
2583
2584                 return $sql;
2585         }
2586
2587         public function conditional( $cond, $trueVal, $falseVal ) {
2588                 if ( is_array( $cond ) ) {
2589                         $cond = $this->makeList( $cond, self::LIST_AND );
2590                 }
2591
2592                 return " (CASE WHEN $cond THEN $trueVal ELSE $falseVal END) ";
2593         }
2594
2595         public function strreplace( $orig, $old, $new ) {
2596                 return "REPLACE({$orig}, {$old}, {$new})";
2597         }
2598
2599         public function getServerUptime() {
2600                 return 0;
2601         }
2602
2603         public function wasDeadlock() {
2604                 return false;
2605         }
2606
2607         public function wasLockTimeout() {
2608                 return false;
2609         }
2610
2611         public function wasErrorReissuable() {
2612                 return false;
2613         }
2614
2615         public function wasReadOnlyError() {
2616                 return false;
2617         }
2618
2619         /**
2620          * Do not use this method outside of Database/DBError classes
2621          *
2622          * @param int|string $errno
2623          * @return bool Whether the given query error was a connection drop
2624          */
2625         public function wasConnectionError( $errno ) {
2626                 return false;
2627         }
2628
2629         public function deadlockLoop() {
2630                 $args = func_get_args();
2631                 $function = array_shift( $args );
2632                 $tries = self::DEADLOCK_TRIES;
2633
2634                 $this->begin( __METHOD__ );
2635
2636                 $retVal = null;
2637                 /** @var Exception $e */
2638                 $e = null;
2639                 do {
2640                         try {
2641                                 $retVal = call_user_func_array( $function, $args );
2642                                 break;
2643                         } catch ( DBQueryError $e ) {
2644                                 if ( $this->wasDeadlock() ) {
2645                                         // Retry after a randomized delay
2646                                         usleep( mt_rand( self::DEADLOCK_DELAY_MIN, self::DEADLOCK_DELAY_MAX ) );
2647                                 } else {
2648                                         // Throw the error back up
2649                                         throw $e;
2650                                 }
2651                         }
2652                 } while ( --$tries > 0 );
2653
2654                 if ( $tries <= 0 ) {
2655                         // Too many deadlocks; give up
2656                         $this->rollback( __METHOD__ );
2657                         throw $e;
2658                 } else {
2659                         $this->commit( __METHOD__ );
2660
2661                         return $retVal;
2662                 }
2663         }
2664
2665         public function masterPosWait( DBMasterPos $pos, $timeout ) {
2666                 # Real waits are implemented in the subclass.
2667                 return 0;
2668         }
2669
2670         public function getReplicaPos() {
2671                 # Stub
2672                 return false;
2673         }
2674
2675         public function getMasterPos() {
2676                 # Stub
2677                 return false;
2678         }
2679
2680         public function serverIsReadOnly() {
2681                 return false;
2682         }
2683
2684         final public function onTransactionResolution( callable $callback, $fname = __METHOD__ ) {
2685                 if ( !$this->mTrxLevel ) {
2686                         throw new DBUnexpectedError( $this, "No transaction is active." );
2687                 }
2688                 $this->mTrxEndCallbacks[] = [ $callback, $fname ];
2689         }
2690
2691         final public function onTransactionIdle( callable $callback, $fname = __METHOD__ ) {
2692                 $this->mTrxIdleCallbacks[] = [ $callback, $fname ];
2693                 if ( !$this->mTrxLevel ) {
2694                         $this->runOnTransactionIdleCallbacks( self::TRIGGER_IDLE );
2695                 }
2696         }
2697
2698         final public function onTransactionPreCommitOrIdle( callable $callback, $fname = __METHOD__ ) {
2699                 if ( $this->mTrxLevel || $this->getFlag( self::DBO_TRX ) ) {
2700                         // As long as DBO_TRX is set, writes will accumulate until the load balancer issues
2701                         // an implicit commit of all peer databases. This is true even if a transaction has
2702                         // not yet been triggered by writes; make sure $callback runs *after* any such writes.
2703                         $this->mTrxPreCommitCallbacks[] = [ $callback, $fname ];
2704                 } else {
2705                         // No transaction is active nor will start implicitly, so make one for this callback
2706                         $this->startAtomic( __METHOD__ );
2707                         try {
2708                                 call_user_func( $callback );
2709                                 $this->endAtomic( __METHOD__ );
2710                         } catch ( Exception $e ) {
2711                                 $this->rollback( __METHOD__, self::FLUSHING_INTERNAL );
2712                                 throw $e;
2713                         }
2714                 }
2715         }
2716
2717         final public function setTransactionListener( $name, callable $callback = null ) {
2718                 if ( $callback ) {
2719                         $this->mTrxRecurringCallbacks[$name] = $callback;
2720                 } else {
2721                         unset( $this->mTrxRecurringCallbacks[$name] );
2722                 }
2723         }
2724
2725         /**
2726          * Whether to disable running of post-COMMIT/ROLLBACK callbacks
2727          *
2728          * This method should not be used outside of Database/LoadBalancer
2729          *
2730          * @param bool $suppress
2731          * @since 1.28
2732          */
2733         final public function setTrxEndCallbackSuppression( $suppress ) {
2734                 $this->mTrxEndCallbacksSuppressed = $suppress;
2735         }
2736
2737         /**
2738          * Actually run and consume any "on transaction idle/resolution" callbacks.
2739          *
2740          * This method should not be used outside of Database/LoadBalancer
2741          *
2742          * @param int $trigger IDatabase::TRIGGER_* constant
2743          * @since 1.20
2744          * @throws Exception
2745          */
2746         public function runOnTransactionIdleCallbacks( $trigger ) {
2747                 if ( $this->mTrxEndCallbacksSuppressed ) {
2748                         return;
2749                 }
2750
2751                 $autoTrx = $this->getFlag( self::DBO_TRX ); // automatic begin() enabled?
2752                 /** @var Exception $e */
2753                 $e = null; // first exception
2754                 do { // callbacks may add callbacks :)
2755                         $callbacks = array_merge(
2756                                 $this->mTrxIdleCallbacks,
2757                                 $this->mTrxEndCallbacks // include "transaction resolution" callbacks
2758                         );
2759                         $this->mTrxIdleCallbacks = []; // consumed (and recursion guard)
2760                         $this->mTrxEndCallbacks = []; // consumed (recursion guard)
2761                         foreach ( $callbacks as $callback ) {
2762                                 try {
2763                                         list( $phpCallback ) = $callback;
2764                                         $this->clearFlag( self::DBO_TRX ); // make each query its own transaction
2765                                         call_user_func_array( $phpCallback, [ $trigger ] );
2766                                         if ( $autoTrx ) {
2767                                                 $this->setFlag( self::DBO_TRX ); // restore automatic begin()
2768                                         } else {
2769                                                 $this->clearFlag( self::DBO_TRX ); // restore auto-commit
2770                                         }
2771                                 } catch ( Exception $ex ) {
2772                                         call_user_func( $this->errorLogger, $ex );
2773                                         $e = $e ?: $ex;
2774                                         // Some callbacks may use startAtomic/endAtomic, so make sure
2775                                         // their transactions are ended so other callbacks don't fail
2776                                         if ( $this->trxLevel() ) {
2777                                                 $this->rollback( __METHOD__, self::FLUSHING_INTERNAL );
2778                                         }
2779                                 }
2780                         }
2781                 } while ( count( $this->mTrxIdleCallbacks ) );
2782
2783                 if ( $e instanceof Exception ) {
2784                         throw $e; // re-throw any first exception
2785                 }
2786         }
2787
2788         /**
2789          * Actually run and consume any "on transaction pre-commit" callbacks.
2790          *
2791          * This method should not be used outside of Database/LoadBalancer
2792          *
2793          * @since 1.22
2794          * @throws Exception
2795          */
2796         public function runOnTransactionPreCommitCallbacks() {
2797                 $e = null; // first exception
2798                 do { // callbacks may add callbacks :)
2799                         $callbacks = $this->mTrxPreCommitCallbacks;
2800                         $this->mTrxPreCommitCallbacks = []; // consumed (and recursion guard)
2801                         foreach ( $callbacks as $callback ) {
2802                                 try {
2803                                         list( $phpCallback ) = $callback;
2804                                         call_user_func( $phpCallback );
2805                                 } catch ( Exception $ex ) {
2806                                         call_user_func( $this->errorLogger, $ex );
2807                                         $e = $e ?: $ex;
2808                                 }
2809                         }
2810                 } while ( count( $this->mTrxPreCommitCallbacks ) );
2811
2812                 if ( $e instanceof Exception ) {
2813                         throw $e; // re-throw any first exception
2814                 }
2815         }
2816
2817         /**
2818          * Actually run any "transaction listener" callbacks.
2819          *
2820          * This method should not be used outside of Database/LoadBalancer
2821          *
2822          * @param int $trigger IDatabase::TRIGGER_* constant
2823          * @throws Exception
2824          * @since 1.20
2825          */
2826         public function runTransactionListenerCallbacks( $trigger ) {
2827                 if ( $this->mTrxEndCallbacksSuppressed ) {
2828                         return;
2829                 }
2830
2831                 /** @var Exception $e */
2832                 $e = null; // first exception
2833
2834                 foreach ( $this->mTrxRecurringCallbacks as $phpCallback ) {
2835                         try {
2836                                 $phpCallback( $trigger, $this );
2837                         } catch ( Exception $ex ) {
2838                                 call_user_func( $this->errorLogger, $ex );
2839                                 $e = $e ?: $ex;
2840                         }
2841                 }
2842
2843                 if ( $e instanceof Exception ) {
2844                         throw $e; // re-throw any first exception
2845                 }
2846         }
2847
2848         final public function startAtomic( $fname = __METHOD__ ) {
2849                 if ( !$this->mTrxLevel ) {
2850                         $this->begin( $fname, self::TRANSACTION_INTERNAL );
2851                         // If DBO_TRX is set, a series of startAtomic/endAtomic pairs will result
2852                         // in all changes being in one transaction to keep requests transactional.
2853                         if ( !$this->getFlag( self::DBO_TRX ) ) {
2854                                 $this->mTrxAutomaticAtomic = true;
2855                         }
2856                 }
2857
2858                 $this->mTrxAtomicLevels[] = $fname;
2859         }
2860
2861         final public function endAtomic( $fname = __METHOD__ ) {
2862                 if ( !$this->mTrxLevel ) {
2863                         throw new DBUnexpectedError( $this, "No atomic transaction is open (got $fname)." );
2864                 }
2865                 if ( !$this->mTrxAtomicLevels ||
2866                         array_pop( $this->mTrxAtomicLevels ) !== $fname
2867                 ) {
2868                         throw new DBUnexpectedError( $this, "Invalid atomic section ended (got $fname)." );
2869                 }
2870
2871                 if ( !$this->mTrxAtomicLevels && $this->mTrxAutomaticAtomic ) {
2872                         $this->commit( $fname, self::FLUSHING_INTERNAL );
2873                 }
2874         }
2875
2876         final public function doAtomicSection( $fname, callable $callback ) {
2877                 $this->startAtomic( $fname );
2878                 try {
2879                         $res = call_user_func_array( $callback, [ $this, $fname ] );
2880                 } catch ( Exception $e ) {
2881                         $this->rollback( $fname, self::FLUSHING_INTERNAL );
2882                         throw $e;
2883                 }
2884                 $this->endAtomic( $fname );
2885
2886                 return $res;
2887         }
2888
2889         final public function begin( $fname = __METHOD__, $mode = self::TRANSACTION_EXPLICIT ) {
2890                 // Protect against mismatched atomic section, transaction nesting, and snapshot loss
2891                 if ( $this->mTrxLevel ) {
2892                         if ( $this->mTrxAtomicLevels ) {
2893                                 $levels = implode( ', ', $this->mTrxAtomicLevels );
2894                                 $msg = "$fname: Got explicit BEGIN while atomic section(s) $levels are open.";
2895                                 throw new DBUnexpectedError( $this, $msg );
2896                         } elseif ( !$this->mTrxAutomatic ) {
2897                                 $msg = "$fname: Explicit transaction already active (from {$this->mTrxFname}).";
2898                                 throw new DBUnexpectedError( $this, $msg );
2899                         } else {
2900                                 // @TODO: make this an exception at some point
2901                                 $msg = "$fname: Implicit transaction already active (from {$this->mTrxFname}).";
2902                                 $this->queryLogger->error( $msg );
2903                                 return; // join the main transaction set
2904                         }
2905                 } elseif ( $this->getFlag( self::DBO_TRX ) && $mode !== self::TRANSACTION_INTERNAL ) {
2906                         // @TODO: make this an exception at some point
2907                         $msg = "$fname: Implicit transaction expected (DBO_TRX set).";
2908                         $this->queryLogger->error( $msg );
2909                         return; // let any writes be in the main transaction
2910                 }
2911
2912                 // Avoid fatals if close() was called
2913                 $this->assertOpen();
2914
2915                 $this->doBegin( $fname );
2916                 $this->mTrxTimestamp = microtime( true );
2917                 $this->mTrxFname = $fname;
2918                 $this->mTrxDoneWrites = false;
2919                 $this->mTrxAutomaticAtomic = false;
2920                 $this->mTrxAtomicLevels = [];
2921                 $this->mTrxShortId = sprintf( '%06x', mt_rand( 0, 0xffffff ) );
2922                 $this->mTrxWriteDuration = 0.0;
2923                 $this->mTrxWriteQueryCount = 0;
2924                 $this->mTrxWriteAffectedRows = 0;
2925                 $this->mTrxWriteAdjDuration = 0.0;
2926                 $this->mTrxWriteAdjQueryCount = 0;
2927                 $this->mTrxWriteCallers = [];
2928                 // First SELECT after BEGIN will establish the snapshot in REPEATABLE-READ.
2929                 // Get an estimate of the replica DB lag before then, treating estimate staleness
2930                 // as lag itself just to be safe
2931                 $status = $this->getApproximateLagStatus();
2932                 $this->mTrxReplicaLag = $status['lag'] + ( microtime( true ) - $status['since'] );
2933                 // T147697: make explicitTrxActive() return true until begin() finishes. This way, no
2934                 // caller will think its OK to muck around with the transaction just because startAtomic()
2935                 // has not yet completed (e.g. setting mTrxAtomicLevels).
2936                 $this->mTrxAutomatic = ( $mode === self::TRANSACTION_INTERNAL );
2937         }
2938
2939         /**
2940          * Issues the BEGIN command to the database server.
2941          *
2942          * @see Database::begin()
2943          * @param string $fname
2944          */
2945         protected function doBegin( $fname ) {
2946                 $this->query( 'BEGIN', $fname );
2947                 $this->mTrxLevel = 1;
2948         }
2949
2950         final public function commit( $fname = __METHOD__, $flush = '' ) {
2951                 if ( $this->mTrxLevel && $this->mTrxAtomicLevels ) {
2952                         // There are still atomic sections open. This cannot be ignored
2953                         $levels = implode( ', ', $this->mTrxAtomicLevels );
2954                         throw new DBUnexpectedError(
2955                                 $this,
2956                                 "$fname: Got COMMIT while atomic sections $levels are still open."
2957                         );
2958                 }
2959
2960                 if ( $flush === self::FLUSHING_INTERNAL || $flush === self::FLUSHING_ALL_PEERS ) {
2961                         if ( !$this->mTrxLevel ) {
2962                                 return; // nothing to do
2963                         } elseif ( !$this->mTrxAutomatic ) {
2964                                 throw new DBUnexpectedError(
2965                                         $this,
2966                                         "$fname: Flushing an explicit transaction, getting out of sync."
2967                                 );
2968                         }
2969                 } else {
2970                         if ( !$this->mTrxLevel ) {
2971                                 $this->queryLogger->error(
2972                                         "$fname: No transaction to commit, something got out of sync." );
2973                                 return; // nothing to do
2974                         } elseif ( $this->mTrxAutomatic ) {
2975                                 // @TODO: make this an exception at some point
2976                                 $msg = "$fname: Explicit commit of implicit transaction.";
2977                                 $this->queryLogger->error( $msg );
2978                                 return; // wait for the main transaction set commit round
2979                         }
2980                 }
2981
2982                 // Avoid fatals if close() was called
2983                 $this->assertOpen();
2984
2985                 $this->runOnTransactionPreCommitCallbacks();
2986                 $writeTime = $this->pendingWriteQueryDuration( self::ESTIMATE_DB_APPLY );
2987                 $this->doCommit( $fname );
2988                 if ( $this->mTrxDoneWrites ) {
2989                         $this->mLastWriteTime = microtime( true );
2990                         $this->trxProfiler->transactionWritingOut(
2991                                 $this->mServer,
2992                                 $this->mDBname,
2993                                 $this->mTrxShortId,
2994                                 $writeTime,
2995                                 $this->mTrxWriteAffectedRows
2996                         );
2997                 }
2998
2999                 $this->runOnTransactionIdleCallbacks( self::TRIGGER_COMMIT );
3000                 $this->runTransactionListenerCallbacks( self::TRIGGER_COMMIT );
3001         }
3002
3003         /**
3004          * Issues the COMMIT command to the database server.
3005          *
3006          * @see Database::commit()
3007          * @param string $fname
3008          */
3009         protected function doCommit( $fname ) {
3010                 if ( $this->mTrxLevel ) {
3011                         $this->query( 'COMMIT', $fname );
3012                         $this->mTrxLevel = 0;
3013                 }
3014         }
3015
3016         final public function rollback( $fname = __METHOD__, $flush = '' ) {
3017                 if ( $flush === self::FLUSHING_INTERNAL || $flush === self::FLUSHING_ALL_PEERS ) {
3018                         if ( !$this->mTrxLevel ) {
3019                                 return; // nothing to do
3020                         }
3021                 } else {
3022                         if ( !$this->mTrxLevel ) {
3023                                 $this->queryLogger->error(
3024                                         "$fname: No transaction to rollback, something got out of sync." );
3025                                 return; // nothing to do
3026                         } elseif ( $this->getFlag( self::DBO_TRX ) ) {
3027                                 throw new DBUnexpectedError(
3028                                         $this,
3029                                         "$fname: Expected mass rollback of all peer databases (DBO_TRX set)."
3030                                 );
3031                         }
3032                 }
3033
3034                 // Avoid fatals if close() was called
3035                 $this->assertOpen();
3036
3037                 $this->doRollback( $fname );
3038                 $this->mTrxAtomicLevels = [];
3039                 if ( $this->mTrxDoneWrites ) {
3040                         $this->trxProfiler->transactionWritingOut(
3041                                 $this->mServer,
3042                                 $this->mDBname,
3043                                 $this->mTrxShortId
3044                         );
3045                 }
3046
3047                 $this->mTrxIdleCallbacks = []; // clear
3048                 $this->mTrxPreCommitCallbacks = []; // clear
3049                 $this->runOnTransactionIdleCallbacks( self::TRIGGER_ROLLBACK );
3050                 $this->runTransactionListenerCallbacks( self::TRIGGER_ROLLBACK );
3051         }
3052
3053         /**
3054          * Issues the ROLLBACK command to the database server.
3055          *
3056          * @see Database::rollback()
3057          * @param string $fname
3058          */
3059         protected function doRollback( $fname ) {
3060                 if ( $this->mTrxLevel ) {
3061                         # Disconnects cause rollback anyway, so ignore those errors
3062                         $ignoreErrors = true;
3063                         $this->query( 'ROLLBACK', $fname, $ignoreErrors );
3064                         $this->mTrxLevel = 0;
3065                 }
3066         }
3067
3068         public function flushSnapshot( $fname = __METHOD__ ) {
3069                 if ( $this->writesOrCallbacksPending() || $this->explicitTrxActive() ) {
3070                         // This only flushes transactions to clear snapshots, not to write data
3071                         $fnames = implode( ', ', $this->pendingWriteAndCallbackCallers() );
3072                         throw new DBUnexpectedError(
3073                                 $this,
3074                                 "$fname: Cannot flush snapshot because writes are pending ($fnames)."
3075                         );
3076                 }
3077
3078                 $this->commit( $fname, self::FLUSHING_INTERNAL );
3079         }
3080
3081         public function explicitTrxActive() {
3082                 return $this->mTrxLevel && ( $this->mTrxAtomicLevels || !$this->mTrxAutomatic );
3083         }
3084
3085         public function duplicateTableStructure(
3086                 $oldName, $newName, $temporary = false, $fname = __METHOD__
3087         ) {
3088                 throw new RuntimeException( __METHOD__ . ' is not implemented in descendant class' );
3089         }
3090
3091         public function listTables( $prefix = null, $fname = __METHOD__ ) {
3092                 throw new RuntimeException( __METHOD__ . ' is not implemented in descendant class' );
3093         }
3094
3095         public function listViews( $prefix = null, $fname = __METHOD__ ) {
3096                 throw new RuntimeException( __METHOD__ . ' is not implemented in descendant class' );
3097         }
3098
3099         public function timestamp( $ts = 0 ) {
3100                 $t = new ConvertibleTimestamp( $ts );
3101                 // Let errors bubble up to avoid putting garbage in the DB
3102                 return $t->getTimestamp( TS_MW );
3103         }
3104
3105         public function timestampOrNull( $ts = null ) {
3106                 if ( is_null( $ts ) ) {
3107                         return null;
3108                 } else {
3109                         return $this->timestamp( $ts );
3110                 }
3111         }
3112
3113         /**
3114          * Take the result from a query, and wrap it in a ResultWrapper if
3115          * necessary. Boolean values are passed through as is, to indicate success
3116          * of write queries or failure.
3117          *
3118          * Once upon a time, Database::query() returned a bare MySQL result
3119          * resource, and it was necessary to call this function to convert it to
3120          * a wrapper. Nowadays, raw database objects are never exposed to external
3121          * callers, so this is unnecessary in external code.
3122          *
3123          * @param bool|ResultWrapper|resource|object $result
3124          * @return bool|ResultWrapper
3125          */
3126         protected function resultObject( $result ) {
3127                 if ( !$result ) {
3128                         return false;
3129                 } elseif ( $result instanceof ResultWrapper ) {
3130                         return $result;
3131                 } elseif ( $result === true ) {
3132                         // Successful write query
3133                         return $result;
3134                 } else {
3135                         return new ResultWrapper( $this, $result );
3136                 }
3137         }
3138
3139         public function ping( &$rtt = null ) {
3140                 // Avoid hitting the server if it was hit recently
3141                 if ( $this->isOpen() && ( microtime( true ) - $this->lastPing ) < self::PING_TTL ) {
3142                         if ( !func_num_args() || $this->mRTTEstimate > 0 ) {
3143                                 $rtt = $this->mRTTEstimate;
3144                                 return true; // don't care about $rtt
3145                         }
3146                 }
3147
3148                 // This will reconnect if possible or return false if not
3149                 $this->clearFlag( self::DBO_TRX, self::REMEMBER_PRIOR );
3150                 $ok = ( $this->query( self::PING_QUERY, __METHOD__, true ) !== false );
3151                 $this->restoreFlags( self::RESTORE_PRIOR );
3152
3153                 if ( $ok ) {
3154                         $rtt = $this->mRTTEstimate;
3155                 }
3156
3157                 return $ok;
3158         }
3159
3160         /**
3161          * Close existing database connection and open a new connection
3162          *
3163          * @return bool True if new connection is opened successfully, false if error
3164          */
3165         protected function reconnect() {
3166                 $this->closeConnection();
3167                 $this->mOpened = false;
3168                 $this->mConn = false;
3169                 try {
3170                         $this->open( $this->mServer, $this->mUser, $this->mPassword, $this->mDBname );
3171                         $this->lastPing = microtime( true );
3172                         $ok = true;
3173                 } catch ( DBConnectionError $e ) {
3174                         $ok = false;
3175                 }
3176
3177                 return $ok;
3178         }
3179
3180         public function getSessionLagStatus() {
3181                 return $this->getTransactionLagStatus() ?: $this->getApproximateLagStatus();
3182         }
3183
3184         /**
3185          * Get the replica DB lag when the current transaction started
3186          *
3187          * This is useful when transactions might use snapshot isolation
3188          * (e.g. REPEATABLE-READ in innodb), so the "real" lag of that data
3189          * is this lag plus transaction duration. If they don't, it is still
3190          * safe to be pessimistic. This returns null if there is no transaction.
3191          *
3192          * @return array|null ('lag': seconds or false on error, 'since': UNIX timestamp of BEGIN)
3193          * @since 1.27
3194          */
3195         protected function getTransactionLagStatus() {
3196                 return $this->mTrxLevel
3197                         ? [ 'lag' => $this->mTrxReplicaLag, 'since' => $this->trxTimestamp() ]
3198                         : null;
3199         }
3200
3201         /**
3202          * Get a replica DB lag estimate for this server
3203          *
3204          * @return array ('lag': seconds or false on error, 'since': UNIX timestamp of estimate)
3205          * @since 1.27
3206          */
3207         protected function getApproximateLagStatus() {
3208                 return [
3209                         'lag'   => $this->getLBInfo( 'replica' ) ? $this->getLag() : 0,
3210                         'since' => microtime( true )
3211                 ];
3212         }
3213
3214         /**
3215          * Merge the result of getSessionLagStatus() for several DBs
3216          * using the most pessimistic values to estimate the lag of
3217          * any data derived from them in combination
3218          *
3219          * This is information is useful for caching modules
3220          *
3221          * @see WANObjectCache::set()
3222          * @see WANObjectCache::getWithSetCallback()
3223          *
3224          * @param IDatabase $db1
3225          * @param IDatabase $dbs,...
3226          * @return array Map of values:
3227          *   - lag: highest lag of any of the DBs or false on error (e.g. replication stopped)
3228          *   - since: oldest UNIX timestamp of any of the DB lag estimates
3229          *   - pending: whether any of the DBs have uncommitted changes
3230          * @since 1.27
3231          */
3232         public static function getCacheSetOptions( IDatabase $db1 ) {
3233                 $res = [ 'lag' => 0, 'since' => INF, 'pending' => false ];
3234                 foreach ( func_get_args() as $db ) {
3235                         /** @var IDatabase $db */
3236                         $status = $db->getSessionLagStatus();
3237                         if ( $status['lag'] === false ) {
3238                                 $res['lag'] = false;
3239                         } elseif ( $res['lag'] !== false ) {
3240                                 $res['lag'] = max( $res['lag'], $status['lag'] );
3241                         }
3242                         $res['since'] = min( $res['since'], $status['since'] );
3243                         $res['pending'] = $res['pending'] ?: $db->writesPending();
3244                 }
3245
3246                 return $res;
3247         }
3248
3249         public function getLag() {
3250                 return 0;
3251         }
3252
3253         public function maxListLen() {
3254                 return 0;
3255         }
3256
3257         public function encodeBlob( $b ) {
3258                 return $b;
3259         }
3260
3261         public function decodeBlob( $b ) {
3262                 if ( $b instanceof Blob ) {
3263                         $b = $b->fetch();
3264                 }
3265                 return $b;
3266         }
3267
3268         public function setSessionOptions( array $options ) {
3269         }
3270
3271         public function sourceFile(
3272                 $filename,
3273                 callable $lineCallback = null,
3274                 callable $resultCallback = null,
3275                 $fname = false,
3276                 callable $inputCallback = null
3277         ) {
3278                 MediaWiki\suppressWarnings();
3279                 $fp = fopen( $filename, 'r' );
3280                 MediaWiki\restoreWarnings();
3281
3282                 if ( false === $fp ) {
3283                         throw new RuntimeException( "Could not open \"{$filename}\".\n" );
3284                 }
3285
3286                 if ( !$fname ) {
3287                         $fname = __METHOD__ . "( $filename )";
3288                 }
3289
3290                 try {
3291                         $error = $this->sourceStream(
3292                                 $fp, $lineCallback, $resultCallback, $fname, $inputCallback );
3293                 } catch ( Exception $e ) {
3294                         fclose( $fp );
3295                         throw $e;
3296                 }
3297
3298                 fclose( $fp );
3299
3300                 return $error;
3301         }
3302
3303         public function setSchemaVars( $vars ) {
3304                 $this->mSchemaVars = $vars;
3305         }
3306
3307         public function sourceStream(
3308                 $fp,
3309                 callable $lineCallback = null,
3310                 callable $resultCallback = null,
3311                 $fname = __METHOD__,
3312                 callable $inputCallback = null
3313         ) {
3314                 $cmd = '';
3315
3316                 while ( !feof( $fp ) ) {
3317                         if ( $lineCallback ) {
3318                                 call_user_func( $lineCallback );
3319                         }
3320
3321                         $line = trim( fgets( $fp ) );
3322
3323                         if ( $line == '' ) {
3324                                 continue;
3325                         }
3326
3327                         if ( '-' == $line[0] && '-' == $line[1] ) {
3328                                 continue;
3329                         }
3330
3331                         if ( $cmd != '' ) {
3332                                 $cmd .= ' ';
3333                         }
3334
3335                         $done = $this->streamStatementEnd( $cmd, $line );
3336
3337                         $cmd .= "$line\n";
3338
3339                         if ( $done || feof( $fp ) ) {
3340                                 $cmd = $this->replaceVars( $cmd );
3341
3342                                 if ( !$inputCallback || call_user_func( $inputCallback, $cmd ) ) {
3343                                         $res = $this->query( $cmd, $fname );
3344
3345                                         if ( $resultCallback ) {
3346                                                 call_user_func( $resultCallback, $res, $this );
3347                                         }
3348
3349                                         if ( false === $res ) {
3350                                                 $err = $this->lastError();
3351
3352                                                 return "Query \"{$cmd}\" failed with error code \"$err\".\n";
3353                                         }
3354                                 }
3355                                 $cmd = '';
3356                         }
3357                 }
3358
3359                 return true;
3360         }
3361
3362         /**
3363          * Called by sourceStream() to check if we've reached a statement end
3364          *
3365          * @param string &$sql SQL assembled so far
3366          * @param string &$newLine New line about to be added to $sql
3367          * @return bool Whether $newLine contains end of the statement
3368          */
3369         public function streamStatementEnd( &$sql, &$newLine ) {
3370                 if ( $this->delimiter ) {
3371                         $prev = $newLine;
3372                         $newLine = preg_replace(
3373                                 '/' . preg_quote( $this->delimiter, '/' ) . '$/', '', $newLine );
3374                         if ( $newLine != $prev ) {
3375                                 return true;
3376                         }
3377                 }
3378
3379                 return false;
3380         }
3381
3382         /**
3383          * Database independent variable replacement. Replaces a set of variables
3384          * in an SQL statement with their contents as given by $this->getSchemaVars().
3385          *
3386          * Supports '{$var}' `{$var}` and / *$var* / (without the spaces) style variables.
3387          *
3388          * - '{$var}' should be used for text and is passed through the database's
3389          *   addQuotes method.
3390          * - `{$var}` should be used for identifiers (e.g. table and database names).
3391          *   It is passed through the database's addIdentifierQuotes method which
3392          *   can be overridden if the database uses something other than backticks.
3393          * - / *_* / or / *$wgDBprefix* / passes the name that follows through the
3394          *   database's tableName method.
3395          * - / *i* / passes the name that follows through the database's indexName method.
3396          * - In all other cases, / *$var* / is left unencoded. Except for table options,
3397          *   its use should be avoided. In 1.24 and older, string encoding was applied.
3398          *
3399          * @param string $ins SQL statement to replace variables in
3400          * @return string The new SQL statement with variables replaced
3401          */
3402         protected function replaceVars( $ins ) {
3403                 $vars = $this->getSchemaVars();
3404                 return preg_replace_callback(
3405                         '!
3406                                 /\* (\$wgDBprefix|[_i]) \*/ (\w*) | # 1-2. tableName, indexName
3407                                 \'\{\$ (\w+) }\'                  | # 3. addQuotes
3408                                 `\{\$ (\w+) }`                    | # 4. addIdentifierQuotes
3409                                 /\*\$ (\w+) \*/                     # 5. leave unencoded
3410                         !x',
3411                         function ( $m ) use ( $vars ) {
3412                                 // Note: Because of <https://bugs.php.net/bug.php?id=51881>,
3413                                 // check for both nonexistent keys *and* the empty string.
3414                                 if ( isset( $m[1] ) && $m[1] !== '' ) {
3415                                         if ( $m[1] === 'i' ) {
3416                                                 return $this->indexName( $m[2] );
3417                                         } else {
3418                                                 return $this->tableName( $m[2] );
3419                                         }
3420                                 } elseif ( isset( $m[3] ) && $m[3] !== '' && array_key_exists( $m[3], $vars ) ) {
3421                                         return $this->addQuotes( $vars[$m[3]] );
3422                                 } elseif ( isset( $m[4] ) && $m[4] !== '' && array_key_exists( $m[4], $vars ) ) {
3423                                         return $this->addIdentifierQuotes( $vars[$m[4]] );
3424                                 } elseif ( isset( $m[5] ) && $m[5] !== '' && array_key_exists( $m[5], $vars ) ) {
3425                                         return $vars[$m[5]];
3426                                 } else {
3427                                         return $m[0];
3428                                 }
3429                         },
3430                         $ins
3431                 );
3432         }
3433
3434         /**
3435          * Get schema variables. If none have been set via setSchemaVars(), then
3436          * use some defaults from the current object.
3437          *
3438          * @return array
3439          */
3440         protected function getSchemaVars() {
3441                 if ( $this->mSchemaVars ) {
3442                         return $this->mSchemaVars;
3443                 } else {
3444                         return $this->getDefaultSchemaVars();
3445                 }
3446         }
3447
3448         /**
3449          * Get schema variables to use if none have been set via setSchemaVars().
3450          *
3451          * Override this in derived classes to provide variables for tables.sql
3452          * and SQL patch files.
3453          *
3454          * @return array
3455          */
3456         protected function getDefaultSchemaVars() {
3457                 return [];
3458         }
3459
3460         public function lockIsFree( $lockName, $method ) {
3461                 return true;
3462         }
3463
3464         public function lock( $lockName, $method, $timeout = 5 ) {
3465                 $this->mNamedLocksHeld[$lockName] = 1;
3466
3467                 return true;
3468         }
3469
3470         public function unlock( $lockName, $method ) {
3471                 unset( $this->mNamedLocksHeld[$lockName] );
3472
3473                 return true;
3474         }
3475
3476         public function getScopedLockAndFlush( $lockKey, $fname, $timeout ) {
3477                 if ( $this->writesOrCallbacksPending() ) {
3478                         // This only flushes transactions to clear snapshots, not to write data
3479                         $fnames = implode( ', ', $this->pendingWriteAndCallbackCallers() );
3480                         throw new DBUnexpectedError(
3481                                 $this,
3482                                 "$fname: Cannot flush pre-lock snapshot because writes are pending ($fnames)."
3483                         );
3484                 }
3485
3486                 if ( !$this->lock( $lockKey, $fname, $timeout ) ) {
3487                         return null;
3488                 }
3489
3490                 $unlocker = new ScopedCallback( function () use ( $lockKey, $fname ) {
3491                         if ( $this->trxLevel() ) {
3492                                 // There is a good chance an exception was thrown, causing any early return
3493                                 // from the caller. Let any error handler get a chance to issue rollback().
3494                                 // If there isn't one, let the error bubble up and trigger server-side rollback.
3495                                 $this->onTransactionResolution(
3496                                         function () use ( $lockKey, $fname ) {
3497                                                 $this->unlock( $lockKey, $fname );
3498                                         },
3499                                         $fname
3500                                 );
3501                         } else {
3502                                 $this->unlock( $lockKey, $fname );
3503                         }
3504                 } );
3505
3506                 $this->commit( $fname, self::FLUSHING_INTERNAL );
3507
3508                 return $unlocker;
3509         }
3510
3511         public function namedLocksEnqueue() {
3512                 return false;
3513         }
3514
3515         public function tableLocksHaveTransactionScope() {
3516                 return true;
3517         }
3518
3519         final public function lockTables( array $read, array $write, $method ) {
3520                 if ( $this->writesOrCallbacksPending() ) {
3521                         throw new DBUnexpectedError( $this, "Transaction writes or callbacks still pending." );
3522                 }
3523
3524                 if ( $this->tableLocksHaveTransactionScope() ) {
3525                         $this->startAtomic( $method );
3526                 }
3527
3528                 return $this->doLockTables( $read, $write, $method );
3529         }
3530
3531         /**
3532          * Helper function for lockTables() that handles the actual table locking
3533          *
3534          * @param array $read Array of tables to lock for read access
3535          * @param array $write Array of tables to lock for write access
3536          * @param string $method Name of caller
3537          * @return true
3538          */
3539         protected function doLockTables( array $read, array $write, $method ) {
3540                 return true;
3541         }
3542
3543         final public function unlockTables( $method ) {
3544                 if ( $this->tableLocksHaveTransactionScope() ) {
3545                         $this->endAtomic( $method );
3546
3547                         return true; // locks released on COMMIT/ROLLBACK
3548                 }
3549
3550                 return $this->doUnlockTables( $method );
3551         }
3552
3553         /**
3554          * Helper function for unlockTables() that handles the actual table unlocking
3555          *
3556          * @param string $method Name of caller
3557          * @return true
3558          */
3559         protected function doUnlockTables( $method ) {
3560                 return true;
3561         }
3562
3563         /**
3564          * Delete a table
3565          * @param string $tableName
3566          * @param string $fName
3567          * @return bool|ResultWrapper
3568          * @since 1.18
3569          */
3570         public function dropTable( $tableName, $fName = __METHOD__ ) {
3571                 if ( !$this->tableExists( $tableName, $fName ) ) {
3572                         return false;
3573                 }
3574                 $sql = "DROP TABLE " . $this->tableName( $tableName ) . " CASCADE";
3575
3576                 return $this->query( $sql, $fName );
3577         }
3578
3579         public function getInfinity() {
3580                 return 'infinity';
3581         }
3582
3583         public function encodeExpiry( $expiry ) {
3584                 return ( $expiry == '' || $expiry == 'infinity' || $expiry == $this->getInfinity() )
3585                         ? $this->getInfinity()
3586                         : $this->timestamp( $expiry );
3587         }
3588
3589         public function decodeExpiry( $expiry, $format = TS_MW ) {
3590                 if ( $expiry == '' || $expiry == 'infinity' || $expiry == $this->getInfinity() ) {
3591                         return 'infinity';
3592                 }
3593
3594                 return ConvertibleTimestamp::convert( $format, $expiry );
3595         }
3596
3597         public function setBigSelects( $value = true ) {
3598                 // no-op
3599         }
3600
3601         public function isReadOnly() {
3602                 return ( $this->getReadOnlyReason() !== false );
3603         }
3604
3605         /**
3606          * @return string|bool Reason this DB is read-only or false if it is not
3607          */
3608         protected function getReadOnlyReason() {
3609                 $reason = $this->getLBInfo( 'readOnlyReason' );
3610
3611                 return is_string( $reason ) ? $reason : false;
3612         }
3613
3614         public function setTableAliases( array $aliases ) {
3615                 $this->tableAliases = $aliases;
3616         }
3617
3618         /**
3619          * @return bool Whether a DB user is required to access the DB
3620          * @since 1.28
3621          */
3622         protected function requiresDatabaseUser() {
3623                 return true;
3624         }
3625
3626         /**
3627          * Get the underlying binding handle, mConn
3628          *
3629          * Makes sure that mConn is set (disconnects and ping() failure can unset it).
3630          * This catches broken callers than catch and ignore disconnection exceptions.
3631          * Unlike checking isOpen(), this is safe to call inside of open().
3632          *
3633          * @return resource|object
3634          * @throws DBUnexpectedError
3635          * @since 1.26
3636          */
3637         protected function getBindingHandle() {
3638                 if ( !$this->mConn ) {
3639                         throw new DBUnexpectedError(
3640                                 $this,
3641                                 'DB connection was already closed or the connection dropped.'
3642                         );
3643                 }
3644
3645                 return $this->mConn;
3646         }
3647
3648         /**
3649          * @since 1.19
3650          * @return string
3651          */
3652         public function __toString() {
3653                 return (string)$this->mConn;
3654         }
3655
3656         /**
3657          * Make sure that copies do not share the same client binding handle
3658          * @throws DBConnectionError
3659          */
3660         public function __clone() {
3661                 $this->connLogger->warning(
3662                         "Cloning " . static::class . " is not recomended; forking connection:\n" .
3663                         ( new RuntimeException() )->getTraceAsString()
3664                 );
3665
3666                 if ( $this->isOpen() ) {
3667                         // Open a new connection resource without messing with the old one
3668                         $this->mOpened = false;
3669                         $this->mConn = false;
3670                         $this->mTrxEndCallbacks = []; // don't copy
3671                         $this->handleSessionLoss(); // no trx or locks anymore
3672                         $this->open( $this->mServer, $this->mUser, $this->mPassword, $this->mDBname );
3673                         $this->lastPing = microtime( true );
3674                 }
3675         }
3676
3677         /**
3678          * Called by serialize. Throw an exception when DB connection is serialized.
3679          * This causes problems on some database engines because the connection is
3680          * not restored on unserialize.
3681          */
3682         public function __sleep() {
3683                 throw new RuntimeException( 'Database serialization may cause problems, since ' .
3684                         'the connection is not restored on wakeup.' );
3685         }
3686
3687         /**
3688          * Run a few simple sanity checks and close dangling connections
3689          */
3690         public function __destruct() {
3691                 if ( $this->mTrxLevel && $this->mTrxDoneWrites ) {
3692                         trigger_error( "Uncommitted DB writes (transaction from {$this->mTrxFname})." );
3693                 }
3694
3695                 $danglingWriters = $this->pendingWriteAndCallbackCallers();
3696                 if ( $danglingWriters ) {
3697                         $fnames = implode( ', ', $danglingWriters );
3698                         trigger_error( "DB transaction writes or callbacks still pending ($fnames)." );
3699                 }
3700
3701                 if ( $this->mConn ) {
3702                         // Avoid connection leaks for sanity. Normally, resources close at script completion.
3703                         // The connection might already be closed in zend/hhvm by now, so suppress warnings.
3704                         \MediaWiki\suppressWarnings();
3705                         $this->closeConnection();
3706                         \MediaWiki\restoreWarnings();
3707                         $this->mConn = false;
3708                         $this->mOpened = false;
3709                 }
3710         }
3711 }
3712
3713 class_alias( Database::class, 'DatabaseBase' ); // b/c for old name
3714 class_alias( Database::class, 'Database' ); // b/c global alias