includes/libs/rdbms/database/Database.php

   1 <?php
   2 /**
   3  * @defgroup Database Database
   4  *
   5  * This file deals with database interface functions
   6  * and query specifics/optimisations.
   7  *
   8  * This program is free software; you can redistribute it and/or modify
   9  * it under the terms of the GNU General Public License as published by
  10  * the Free Software Foundation; either version 2 of the License, or
  11  * (at your option) any later version.
  12  *
  13  * This program is distributed in the hope that it will be useful,
  14  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  15  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
  16  * GNU General Public License for more details.
  17  *
  18  * You should have received a copy of the GNU General Public License along
  19  * with this program; if not, write to the Free Software Foundation, Inc.,
  20  * 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
  21  * http://www.gnu.org/copyleft/gpl.html
  22  *
  23  * @file
  24  * @ingroup Database
  25  */
  26 use Psr\Log\LoggerAwareInterface;
  27 use Psr\Log\LoggerInterface;
  28 use Wikimedia\ScopedCallback;
  29 use Wikimedia\Rdbms\TransactionProfiler;
  30 use Wikimedia\Rdbms\LikeMatch;
  31 use Wikimedia\Rdbms\DatabaseDomain;
  32 use Wikimedia\Rdbms\ResultWrapper;
  33 use Wikimedia\Rdbms\DBMasterPos;
  34 use Wikimedia\Rdbms\Blob;
  35 use Wikimedia\Timestamp\ConvertibleTimestamp;
  36 use Wikimedia\Rdbms\IDatabase;
  37 use Wikimedia\Rdbms\IMaintainableDatabase;
  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 = .010;
  58         const SLOW_WRITE_SEC = .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 integer */
 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 integer Number of write queries for the current transaction
 201          */
 202         private $mTrxWriteQueryCount = 0;
 203         /**
 204          * @var float Like mTrxWriteQueryCount but excludes lock-bound, easy to replicate, queries
 205          */
 206         private $mTrxWriteAdjDuration = 0.0;
 207         /**
 208          * @var integer Number of write queries counted in mTrxWriteAdjDuration
 209          */
 210         private $mTrxWriteAdjQueryCount = 0;
 211         /**
 212          * @var float RTT time estimate
 213          */
 214         private $mRTTEstimate = 0.0;
 215
 216         /** @var array Map of (name => 1) for locks obtained via lock() */
 217         private $mNamedLocksHeld = [];
 218         /** @var array Map of (table name => 1) for TEMPORARY tables */
 219         protected $mSessionTempTables = [];
 220
 221         /** @var IDatabase|null Lazy handle to the master DB this server replicates from */
 222         private $lazyMasterHandle;
 223
 224         /** @var float UNIX timestamp */
 225         protected $lastPing = 0.0;
 226
 227         /** @var int[] Prior mFlags values */
 228         private $priorFlags = [];
 229
 230         /** @var object|string Class name or object With profileIn/profileOut methods */
 231         protected $profiler;
 232         /** @var TransactionProfiler */
 233         protected $trxProfiler;
 234
 235         /**
 236          * Constructor and database handle and attempt to connect to the DB server
 237          *
 238          * IDatabase classes should not be constructed directly in external
 239          * code. Database::factory() should be used instead.
 240          *
 241          * @param array $params Parameters passed from Database::factory()
 242          */
 243         function __construct( array $params ) {
 244                 $server = $params['host'];
 245                 $user = $params['user'];
 246                 $password = $params['password'];
 247                 $dbName = $params['dbname'];
 248
 249                 $this->mSchema = $params['schema'];
 250                 $this->mTablePrefix = $params['tablePrefix'];
 251
 252                 $this->cliMode = $params['cliMode'];
 253                 // Agent name is added to SQL queries in a comment, so make sure it can't break out
 254                 $this->agent = str_replace( '/', '-', $params['agent'] );
 255
 256                 $this->mFlags = $params['flags'];
 257                 if ( $this->mFlags & self::DBO_DEFAULT ) {
 258                         if ( $this->cliMode ) {
 259                                 $this->mFlags &= ~self::DBO_TRX;
 260                         } else {
 261                                 $this->mFlags |= self::DBO_TRX;
 262                         }
 263                 }
 264
 265                 $this->mSessionVars = $params['variables'];
 266
 267                 $this->srvCache = isset( $params['srvCache'] )
 268                         ? $params['srvCache']
 269                         : new HashBagOStuff();
 270
 271                 $this->profiler = $params['profiler'];
 272                 $this->trxProfiler = $params['trxProfiler'];
 273                 $this->connLogger = $params['connLogger'];
 274                 $this->queryLogger = $params['queryLogger'];
 275                 $this->errorLogger = $params['errorLogger'];
 276
 277                 // Set initial dummy domain until open() sets the final DB/prefix
 278                 $this->currentDomain = DatabaseDomain::newUnspecified();
 279
 280                 if ( $user ) {
 281                         $this->open( $server, $user, $password, $dbName );
 282                 } elseif ( $this->requiresDatabaseUser() ) {
 283                         throw new InvalidArgumentException( "No database user provided." );
 284                 }
 285
 286                 // Set the domain object after open() sets the relevant fields
 287                 if ( $this->mDBname != '' ) {
 288                         // Domains with server scope but a table prefix are not used by IDatabase classes
 289                         $this->currentDomain = new DatabaseDomain( $this->mDBname, null, $this->mTablePrefix );
 290                 }
 291         }
 292
 293         /**
 294          * Construct a Database subclass instance given a database type and parameters
 295          *
 296          * This also connects to the database immediately upon object construction
 297          *
 298          * @param string $dbType A possible DB type (sqlite, mysql, postgres)
 299          * @param array $p Parameter map with keys:
 300          *   - host : The hostname of the DB server
 301          *   - user : The name of the database user the client operates under
 302          *   - password : The password for the database user
 303          *   - dbname : The name of the database to use where queries do not specify one.
 304          *      The database must exist or an error might be thrown. Setting this to the empty string
 305          *      will avoid any such errors and make the handle have no implicit database scope. This is
 306          *      useful for queries like SHOW STATUS, CREATE DATABASE, or DROP DATABASE. Note that a
 307          *      "database" in Postgres is rougly equivalent to an entire MySQL server. This the domain
 308          *      in which user names and such are defined, e.g. users are database-specific in Postgres.
 309          *   - schema : The database schema to use (if supported). A "schema" in Postgres is roughly
 310          *      equivalent to a "database" in MySQL. Note that MySQL and SQLite do not use schemas.
 311          *   - tablePrefix : Optional table prefix that is implicitly added on to all table names
 312          *      recognized in queries. This can be used in place of schemas for handle site farms.
 313          *   - flags : Optional bitfield of DBO_* constants that define connection, protocol,
 314          *      buffering, and transaction behavior. It is STRONGLY adviced to leave the DBO_DEFAULT
 315          *      flag in place UNLESS this this database simply acts as a key/value store.
 316          *   - driver: Optional name of a specific DB client driver. For MySQL, there is the old
 317          *      'mysql' driver and the newer 'mysqli' driver.
 318          *   - variables: Optional map of session variables to set after connecting. This can be
 319          *      used to adjust lock timeouts or encoding modes and the like.
 320          *   - connLogger: Optional PSR-3 logger interface instance.
 321          *   - queryLogger: Optional PSR-3 logger interface instance.
 322          *   - profiler: Optional class name or object with profileIn()/profileOut() methods.
 323          *      These will be called in query(), using a simplified version of the SQL that also
 324          *      includes the agent as a SQL comment.
 325          *   - trxProfiler: Optional TransactionProfiler instance.
 326          *   - errorLogger: Optional callback that takes an Exception and logs it.
 327          *   - cliMode: Whether to consider the execution context that of a CLI script.
 328          *   - agent: Optional name used to identify the end-user in query profiling/logging.
 329          *   - srvCache: Optional BagOStuff instance to an APC-style cache.
 330          * @return Database|null If the database driver or extension cannot be found
 331          * @throws InvalidArgumentException If the database driver or extension cannot be found
 332          * @since 1.18
 333          */
 334         final public static function factory( $dbType, $p = [] ) {
 335                 static $canonicalDBTypes = [
 336                         'mysql' => [ 'mysqli', 'mysql' ],
 337                         'postgres' => [],
 338                         'sqlite' => [],
 339                         'oracle' => [],
 340                         'mssql' => [],
 341                 ];
 342
 343                 $driver = false;
 344                 $dbType = strtolower( $dbType );
 345                 if ( isset( $canonicalDBTypes[$dbType] ) && $canonicalDBTypes[$dbType] ) {
 346                         $possibleDrivers = $canonicalDBTypes[$dbType];
 347                         if ( !empty( $p['driver'] ) ) {
 348                                 if ( in_array( $p['driver'], $possibleDrivers ) ) {
 349                                         $driver = $p['driver'];
 350                                 } else {
 351                                         throw new InvalidArgumentException( __METHOD__ .
 352                                                 " type '$dbType' does not support driver '{$p['driver']}'" );
 353                                 }
 354                         } else {
 355                                 foreach ( $possibleDrivers as $posDriver ) {
 356                                         if ( extension_loaded( $posDriver ) ) {
 357                                                 $driver = $posDriver;
 358                                                 break;
 359                                         }
 360                                 }
 361                         }
 362                 } else {
 363                         $driver = $dbType;
 364                 }
 365                 if ( $driver === false || $driver === '' ) {
 366                         throw new InvalidArgumentException( __METHOD__ .
 367                                 " no viable database extension found for type '$dbType'" );
 368                 }
 369
 370                 $class = 'Database' . ucfirst( $driver );
 371                 if ( class_exists( $class ) && is_subclass_of( $class, IDatabase::class ) ) {
 372                         // Resolve some defaults for b/c
 373                         $p['host'] = isset( $p['host'] ) ? $p['host'] : false;
 374                         $p['user'] = isset( $p['user'] ) ? $p['user'] : false;
 375                         $p['password'] = isset( $p['password'] ) ? $p['password'] : false;
 376                         $p['dbname'] = isset( $p['dbname'] ) ? $p['dbname'] : false;
 377                         $p['flags'] = isset( $p['flags'] ) ? $p['flags'] : 0;
 378                         $p['variables'] = isset( $p['variables'] ) ? $p['variables'] : [];
 379                         $p['tablePrefix'] = isset( $p['tablePrefix'] ) ? $p['tablePrefix'] : '';
 380                         $p['schema'] = isset( $p['schema'] ) ? $p['schema'] : '';
 381                         $p['cliMode'] = isset( $p['cliMode'] ) ? $p['cliMode'] : ( PHP_SAPI === 'cli' );
 382                         $p['agent'] = isset( $p['agent'] ) ? $p['agent'] : '';
 383                         if ( !isset( $p['connLogger'] ) ) {
 384                                 $p['connLogger'] = new \Psr\Log\NullLogger();
 385                         }
 386                         if ( !isset( $p['queryLogger'] ) ) {
 387                                 $p['queryLogger'] = new \Psr\Log\NullLogger();
 388                         }
 389                         $p['profiler'] = isset( $p['profiler'] ) ? $p['profiler'] : null;
 390                         if ( !isset( $p['trxProfiler'] ) ) {
 391                                 $p['trxProfiler'] = new TransactionProfiler();
 392                         }
 393                         if ( !isset( $p['errorLogger'] ) ) {
 394                                 $p['errorLogger'] = function ( Exception $e ) {
 395                                         trigger_error( get_class( $e ) . ': ' . $e->getMessage(), E_USER_WARNING );
 396                                 };
 397                         }
 398
 399                         $conn = new $class( $p );
 400                 } else {
 401                         $conn = null;
 402                 }
 403
 404                 return $conn;
 405         }
 406
 407         public function setLogger( LoggerInterface $logger ) {
 408                 $this->queryLogger = $logger;
 409         }
 410
 411         public function getServerInfo() {
 412                 return $this->getServerVersion();
 413         }
 414
 415         public function bufferResults( $buffer = null ) {
 416                 $res = !$this->getFlag( self::DBO_NOBUFFER );
 417                 if ( $buffer !== null ) {
 418                         $buffer
 419                                 ? $this->clearFlag( self::DBO_NOBUFFER )
 420                                 : $this->setFlag( self::DBO_NOBUFFER );
 421                 }
 422
 423                 return $res;
 424         }
 425
 426         /**
 427          * Turns on (false) or off (true) the automatic generation and sending
 428          * of a "we're sorry, but there has been a database error" page on
 429          * database errors. Default is on (false). When turned off, the
 430          * code should use lastErrno() and lastError() to handle the
 431          * situation as appropriate.
 432          *
 433          * Do not use this function outside of the Database classes.
 434          *
 435          * @param null|bool $ignoreErrors
 436          * @return bool The previous value of the flag.
 437          */
 438         protected function ignoreErrors( $ignoreErrors = null ) {
 439                 $res = $this->getFlag( self::DBO_IGNORE );
 440                 if ( $ignoreErrors !== null ) {
 441                         $ignoreErrors
 442                                 ? $this->setFlag( self::DBO_IGNORE )
 443                                 : $this->clearFlag( self::DBO_IGNORE );
 444                 }
 445
 446                 return $res;
 447         }
 448
 449         public function trxLevel() {
 450                 return $this->mTrxLevel;
 451         }
 452
 453         public function trxTimestamp() {
 454                 return $this->mTrxLevel ? $this->mTrxTimestamp : null;
 455         }
 456
 457         public function tablePrefix( $prefix = null ) {
 458                 $old = $this->mTablePrefix;
 459                 if ( $prefix !== null ) {
 460                         $this->mTablePrefix = $prefix;
 461                         $this->currentDomain = ( $this->mDBname != '' )
 462                                 ? new DatabaseDomain( $this->mDBname, null, $this->mTablePrefix )
 463                                 : DatabaseDomain::newUnspecified();
 464                 }
 465
 466                 return $old;
 467         }
 468
 469         public function dbSchema( $schema = null ) {
 470                 $old = $this->mSchema;
 471                 if ( $schema !== null ) {
 472                         $this->mSchema = $schema;
 473                 }
 474
 475                 return $old;
 476         }
 477
 478         public function getLBInfo( $name = null ) {
 479                 if ( is_null( $name ) ) {
 480                         return $this->mLBInfo;
 481                 } else {
 482                         if ( array_key_exists( $name, $this->mLBInfo ) ) {
 483                                 return $this->mLBInfo[$name];
 484                         } else {
 485                                 return null;
 486                         }
 487                 }
 488         }
 489
 490         public function setLBInfo( $name, $value = null ) {
 491                 if ( is_null( $value ) ) {
 492                         $this->mLBInfo = $name;
 493                 } else {
 494                         $this->mLBInfo[$name] = $value;
 495                 }
 496         }
 497
 498         public function setLazyMasterHandle( IDatabase $conn ) {
 499                 $this->lazyMasterHandle = $conn;
 500         }
 501
 502         /**
 503          * @return IDatabase|null
 504          * @see setLazyMasterHandle()
 505          * @since 1.27
 506          */
 507         protected function getLazyMasterHandle() {
 508                 return $this->lazyMasterHandle;
 509         }
 510
 511         public function implicitGroupby() {
 512                 return true;
 513         }
 514
 515         public function implicitOrderby() {
 516                 return true;
 517         }
 518
 519         public function lastQuery() {
 520                 return $this->mLastQuery;
 521         }
 522
 523         public function doneWrites() {
 524                 return (bool)$this->mLastWriteTime;
 525         }
 526
 527         public function lastDoneWrites() {
 528                 return $this->mLastWriteTime ?: false;
 529         }
 530
 531         public function writesPending() {
 532                 return $this->mTrxLevel && $this->mTrxDoneWrites;
 533         }
 534
 535         public function writesOrCallbacksPending() {
 536                 return $this->mTrxLevel && (
 537                         $this->mTrxDoneWrites || $this->mTrxIdleCallbacks || $this->mTrxPreCommitCallbacks
 538                 );
 539         }
 540
 541         public function pendingWriteQueryDuration( $type = self::ESTIMATE_TOTAL ) {
 542                 if ( !$this->mTrxLevel ) {
 543                         return false;
 544                 } elseif ( !$this->mTrxDoneWrites ) {
 545                         return 0.0;
 546                 }
 547
 548                 switch ( $type ) {
 549                         case self::ESTIMATE_DB_APPLY:
 550                                 $this->ping( $rtt );
 551                                 $rttAdjTotal = $this->mTrxWriteAdjQueryCount * $rtt;
 552                                 $applyTime = max( $this->mTrxWriteAdjDuration - $rttAdjTotal, 0 );
 553                                 // For omitted queries, make them count as something at least
 554                                 $omitted = $this->mTrxWriteQueryCount - $this->mTrxWriteAdjQueryCount;
 555                                 $applyTime += self::TINY_WRITE_SEC * $omitted;
 556
 557                                 return $applyTime;
 558                         default: // everything
 559                                 return $this->mTrxWriteDuration;
 560                 }
 561         }
 562
 563         public function pendingWriteCallers() {
 564                 return $this->mTrxLevel ? $this->mTrxWriteCallers : [];
 565         }
 566
 567         protected function pendingWriteAndCallbackCallers() {
 568                 if ( !$this->mTrxLevel ) {
 569                         return [];
 570                 }
 571
 572                 $fnames = $this->mTrxWriteCallers;
 573                 foreach ( [
 574                         $this->mTrxIdleCallbacks,
 575                         $this->mTrxPreCommitCallbacks,
 576                         $this->mTrxEndCallbacks
 577                 ] as $callbacks ) {
 578                         foreach ( $callbacks as $callback ) {
 579                                 $fnames[] = $callback[1];
 580                         }
 581                 }
 582
 583                 return $fnames;
 584         }
 585
 586         public function isOpen() {
 587                 return $this->mOpened;
 588         }
 589
 590         public function setFlag( $flag, $remember = self::REMEMBER_NOTHING ) {
 591                 if ( $remember === self::REMEMBER_PRIOR ) {
 592                         array_push( $this->priorFlags, $this->mFlags );
 593                 }
 594                 $this->mFlags |= $flag;
 595         }
 596
 597         public function clearFlag( $flag, $remember = self::REMEMBER_NOTHING ) {
 598                 if ( $remember === self::REMEMBER_PRIOR ) {
 599                         array_push( $this->priorFlags, $this->mFlags );
 600                 }
 601                 $this->mFlags &= ~$flag;
 602         }
 603
 604         public function restoreFlags( $state = self::RESTORE_PRIOR ) {
 605                 if ( !$this->priorFlags ) {
 606                         return;
 607                 }
 608
 609                 if ( $state === self::RESTORE_INITIAL ) {
 610                         $this->mFlags = reset( $this->priorFlags );
 611                         $this->priorFlags = [];
 612                 } else {
 613                         $this->mFlags = array_pop( $this->priorFlags );
 614                 }
 615         }
 616
 617         public function getFlag( $flag ) {
 618                 return !!( $this->mFlags & $flag );
 619         }
 620
 621         /**
 622          * @param string $name Class field name
 623          * @return mixed
 624          * @deprecated Since 1.28
 625          */
 626         public function getProperty( $name ) {
 627                 return $this->$name;
 628         }
 629
 630         public function getDomainID() {
 631                 return $this->currentDomain->getId();
 632         }
 633
 634         final public function getWikiID() {
 635                 return $this->getDomainID();
 636         }
 637
 638         /**
 639          * Get information about an index into an object
 640          * @param string $table Table name
 641          * @param string $index Index name
 642          * @param string $fname Calling function name
 643          * @return mixed Database-specific index description class or false if the index does not exist
 644          */
 645         abstract function indexInfo( $table, $index, $fname = __METHOD__ );
 646
 647         /**
 648          * Wrapper for addslashes()
 649          *
 650          * @param string $s String to be slashed.
 651          * @return string Slashed string.
 652          */
 653         abstract function strencode( $s );
 654
 655         protected function installErrorHandler() {
 656                 $this->mPHPError = false;
 657                 $this->htmlErrors = ini_set( 'html_errors', '0' );
 658                 set_error_handler( [ $this, 'connectionErrorLogger' ] );
 659         }
 660
 661         /**
 662          * @return bool|string
 663          */
 664         protected function restoreErrorHandler() {
 665                 restore_error_handler();
 666                 if ( $this->htmlErrors !== false ) {
 667                         ini_set( 'html_errors', $this->htmlErrors );
 668                 }
 669
 670                 return $this->getLastPHPError();
 671         }
 672
 673         /**
 674          * @return string|bool Last PHP error for this DB (typically connection errors)
 675          */
 676         protected function getLastPHPError() {
 677                 if ( $this->mPHPError ) {
 678                         $error = preg_replace( '!\[<a.*</a>\]!', '', $this->mPHPError );
 679                         $error = preg_replace( '!^.*?:\s?(.*)$!', '$1', $error );
 680
 681                         return $error;
 682                 }
 683
 684                 return false;
 685         }
 686
 687         /**
 688          * This method should not be used outside of Database classes
 689          *
 690          * @param int $errno
 691          * @param string $errstr
 692          */
 693         public function connectionErrorLogger( $errno, $errstr ) {
 694                 $this->mPHPError = $errstr;
 695         }
 696
 697         /**
 698          * Create a log context to pass to PSR-3 logger functions.
 699          *
 700          * @param array $extras Additional data to add to context
 701          * @return array
 702          */
 703         protected function getLogContext( array $extras = [] ) {
 704                 return array_merge(
 705                         [
 706                                 'db_server' => $this->mServer,
 707                                 'db_name' => $this->mDBname,
 708                                 'db_user' => $this->mUser,
 709                         ],
 710                         $extras
 711                 );
 712         }
 713
 714         public function close() {
 715                 if ( $this->mConn ) {
 716                         if ( $this->trxLevel() ) {
 717                                 $this->commit( __METHOD__, self::FLUSHING_INTERNAL );
 718                         }
 719
 720                         $closed = $this->closeConnection();
 721                         $this->mConn = false;
 722                 } elseif ( $this->mTrxIdleCallbacks || $this->mTrxEndCallbacks ) { // sanity
 723                         throw new RuntimeException( "Transaction callbacks still pending." );
 724                 } else {
 725                         $closed = true;
 726                 }
 727                 $this->mOpened = false;
 728
 729                 return $closed;
 730         }
 731
 732         /**
 733          * Make sure isOpen() returns true as a sanity check
 734          *
 735          * @throws DBUnexpectedError
 736          */
 737         protected function assertOpen() {
 738                 if ( !$this->isOpen() ) {
 739                         throw new DBUnexpectedError( $this, "DB connection was already closed." );
 740                 }
 741         }
 742
 743         /**
 744          * Closes underlying database connection
 745          * @since 1.20
 746          * @return bool Whether connection was closed successfully
 747          */
 748         abstract protected function closeConnection();
 749
 750         public function reportConnectionError( $error = 'Unknown error' ) {
 751                 $myError = $this->lastError();
 752                 if ( $myError ) {
 753                         $error = $myError;
 754                 }
 755
 756                 # New method
 757                 throw new DBConnectionError( $this, $error );
 758         }
 759
 760         /**
 761          * The DBMS-dependent part of query()
 762          *
 763          * @param string $sql SQL query.
 764          * @return ResultWrapper|bool Result object to feed to fetchObject,
 765          *   fetchRow, ...; or false on failure
 766          */
 767         abstract protected function doQuery( $sql );
 768
 769         /**
 770          * Determine whether a query writes to the DB.
 771          * Should return true if unsure.
 772          *
 773          * @param string $sql
 774          * @return bool
 775          */
 776         protected function isWriteQuery( $sql ) {
 777                 return !preg_match(
 778                         '/^(?:SELECT|BEGIN|ROLLBACK|COMMIT|SET|SHOW|EXPLAIN|\(SELECT)\b/i', $sql );
 779         }
 780
 781         /**
 782          * @param $sql
 783          * @return string|null
 784          */
 785         protected function getQueryVerb( $sql ) {
 786                 return preg_match( '/^\s*([a-z]+)/i', $sql, $m ) ? strtoupper( $m[1] ) : null;
 787         }
 788
 789         /**
 790          * Determine whether a SQL statement is sensitive to isolation level.
 791          * A SQL statement is considered transactable if its result could vary
 792          * depending on the transaction isolation level. Operational commands
 793          * such as 'SET' and 'SHOW' are not considered to be transactable.
 794          *
 795          * @param string $sql
 796          * @return bool
 797          */
 798         protected function isTransactableQuery( $sql ) {
 799                 return !in_array(
 800                         $this->getQueryVerb( $sql ),
 801                         [ 'BEGIN', 'COMMIT', 'ROLLBACK', 'SHOW', 'SET', 'CREATE', 'ALTER' ],
 802                         true
 803                 );
 804         }
 805
 806         /**
 807          * @param string $sql A SQL query
 808          * @return bool Whether $sql is SQL for creating/dropping a new TEMPORARY table
 809          */
 810         protected function registerTempTableOperation( $sql ) {
 811                 if ( preg_match(
 812                         '/^CREATE\s+TEMPORARY\s+TABLE\s+(?:IF\s+NOT\s+EXISTS\s+)?[`"\']?(\w+)[`"\']?/i',
 813                         $sql,
 814                         $matches
 815                 ) ) {
 816                         $this->mSessionTempTables[$matches[1]] = 1;
 817
 818                         return true;
 819                 } elseif ( preg_match(
 820                         '/^DROP\s+(?:TEMPORARY\s+)?TABLE\s+(?:IF\s+EXISTS\s+)?[`"\']?(\w+)[`"\']?/i',
 821                         $sql,
 822                         $matches
 823                 ) ) {
 824                         unset( $this->mSessionTempTables[$matches[1]] );
 825
 826                         return true;
 827                 } elseif ( preg_match(
 828                         '/^(?:INSERT\s+(?:\w+\s+)?INTO|UPDATE|DELETE\s+FROM)\s+[`"\']?(\w+)[`"\']?/i',
 829                         $sql,
 830                         $matches
 831                 ) ) {
 832                         return isset( $this->mSessionTempTables[$matches[1]] );
 833                 }
 834
 835                 return false;
 836         }
 837
 838         public function query( $sql, $fname = __METHOD__, $tempIgnore = false ) {
 839                 $priorWritesPending = $this->writesOrCallbacksPending();
 840                 $this->mLastQuery = $sql;
 841
 842                 $isWrite = $this->isWriteQuery( $sql ) && !$this->registerTempTableOperation( $sql );
 843                 if ( $isWrite ) {
 844                         $reason = $this->getReadOnlyReason();
 845                         if ( $reason !== false ) {
 846                                 throw new DBReadOnlyError( $this, "Database is read-only: $reason" );
 847                         }
 848                         # Set a flag indicating that writes have been done
 849                         $this->mLastWriteTime = microtime( true );
 850                 }
 851
 852                 // Add trace comment to the begin of the sql string, right after the operator.
 853                 // Or, for one-word queries (like "BEGIN" or COMMIT") add it to the end (T44598)
 854                 $commentedSql = preg_replace( '/\s|$/', " /* $fname {$this->agent} */ ", $sql, 1 );
 855
 856                 # Start implicit transactions that wrap the request if DBO_TRX is enabled
 857                 if ( !$this->mTrxLevel && $this->getFlag( self::DBO_TRX )
 858                         && $this->isTransactableQuery( $sql )
 859                 ) {
 860                         $this->begin( __METHOD__ . " ($fname)", self::TRANSACTION_INTERNAL );
 861                         $this->mTrxAutomatic = true;
 862                 }
 863
 864                 # Keep track of whether the transaction has write queries pending
 865                 if ( $this->mTrxLevel && !$this->mTrxDoneWrites && $isWrite ) {
 866                         $this->mTrxDoneWrites = true;
 867                         $this->trxProfiler->transactionWritingIn(
 868                                 $this->mServer, $this->mDBname, $this->mTrxShortId );
 869                 }
 870
 871                 if ( $this->getFlag( self::DBO_DEBUG ) ) {
 872                         $this->queryLogger->debug( "{$this->mDBname} {$commentedSql}" );
 873                 }
 874
 875                 # Avoid fatals if close() was called
 876                 $this->assertOpen();
 877
 878                 # Send the query to the server
 879                 $ret = $this->doProfiledQuery( $sql, $commentedSql, $isWrite, $fname );
 880
 881                 # Try reconnecting if the connection was lost
 882                 if ( false === $ret && $this->wasErrorReissuable() ) {
 883                         $recoverable = $this->canRecoverFromDisconnect( $sql, $priorWritesPending );
 884                         # Stash the last error values before anything might clear them
 885                         $lastError = $this->lastError();
 886                         $lastErrno = $this->lastErrno();
 887                         # Update state tracking to reflect transaction loss due to disconnection
 888                         $this->handleSessionLoss();
 889                         if ( $this->reconnect() ) {
 890                                 $msg = __METHOD__ . ": lost connection to {$this->getServer()}; reconnected";
 891                                 $this->connLogger->warning( $msg );
 892                                 $this->queryLogger->warning(
 893                                         "$msg:\n" . ( new RuntimeException() )->getTraceAsString() );
 894
 895                                 if ( !$recoverable ) {
 896                                         # Callers may catch the exception and continue to use the DB
 897                                         $this->reportQueryError( $lastError, $lastErrno, $sql, $fname );
 898                                 } else {
 899                                         # Should be safe to silently retry the query
 900                                         $ret = $this->doProfiledQuery( $sql, $commentedSql, $isWrite, $fname );
 901                                 }
 902                         } else {
 903                                 $msg = __METHOD__ . ": lost connection to {$this->getServer()} permanently";
 904                                 $this->connLogger->error( $msg );
 905                         }
 906                 }
 907
 908                 if ( false === $ret ) {
 909                         # Deadlocks cause the entire transaction to abort, not just the statement.
 910                         # https://dev.mysql.com/doc/refman/5.7/en/innodb-error-handling.html
 911                         # https://www.postgresql.org/docs/9.1/static/explicit-locking.html
 912                         if ( $this->wasDeadlock() ) {
 913                                 if ( $this->explicitTrxActive() || $priorWritesPending ) {
 914                                         $tempIgnore = false; // not recoverable
 915                                 }
 916                                 # Update state tracking to reflect transaction loss
 917                                 $this->handleSessionLoss();
 918                         }
 919
 920                         $this->reportQueryError(
 921                                 $this->lastError(), $this->lastErrno(), $sql, $fname, $tempIgnore );
 922                 }
 923
 924                 $res = $this->resultObject( $ret );
 925
 926                 return $res;
 927         }
 928
 929         private function doProfiledQuery( $sql, $commentedSql, $isWrite, $fname ) {
 930                 $isMaster = !is_null( $this->getLBInfo( 'master' ) );
 931                 # generalizeSQL() will probably cut down the query to reasonable
 932                 # logging size most of the time. The substr is really just a sanity check.
 933                 if ( $isMaster ) {
 934                         $queryProf = 'query-m: ' . substr( self::generalizeSQL( $sql ), 0, 255 );
 935                 } else {
 936                         $queryProf = 'query: ' . substr( self::generalizeSQL( $sql ), 0, 255 );
 937                 }
 938
 939                 # Include query transaction state
 940                 $queryProf .= $this->mTrxShortId ? " [TRX#{$this->mTrxShortId}]" : "";
 941
 942                 $startTime = microtime( true );
 943                 if ( $this->profiler ) {
 944                         call_user_func( [ $this->profiler, 'profileIn' ], $queryProf );
 945                 }
 946                 $ret = $this->doQuery( $commentedSql );
 947                 if ( $this->profiler ) {
 948                         call_user_func( [ $this->profiler, 'profileOut' ], $queryProf );
 949                 }
 950                 $queryRuntime = max( microtime( true ) - $startTime, 0.0 );
 951
 952                 unset( $queryProfSection ); // profile out (if set)
 953
 954                 if ( $ret !== false ) {
 955                         $this->lastPing = $startTime;
 956                         if ( $isWrite && $this->mTrxLevel ) {
 957                                 $this->updateTrxWriteQueryTime( $sql, $queryRuntime );
 958                                 $this->mTrxWriteCallers[] = $fname;
 959                         }
 960                 }
 961
 962                 if ( $sql === self::PING_QUERY ) {
 963                         $this->mRTTEstimate = $queryRuntime;
 964                 }
 965
 966                 $this->trxProfiler->recordQueryCompletion(
 967                         $queryProf, $startTime, $isWrite, $this->affectedRows()
 968                 );
 969                 $this->queryLogger->debug( $sql, [
 970                         'method' => $fname,
 971                         'master' => $isMaster,
 972                         'runtime' => $queryRuntime,
 973                 ] );
 974
 975                 return $ret;
 976         }
 977
 978         /**
 979          * Update the estimated run-time of a query, not counting large row lock times
 980          *
 981          * LoadBalancer can be set to rollback transactions that will create huge replication
 982          * lag. It bases this estimate off of pendingWriteQueryDuration(). Certain simple
 983          * queries, like inserting a row can take a long time due to row locking. This method
 984          * uses some simple heuristics to discount those cases.
 985          *
 986          * @param string $sql A SQL write query
 987          * @param float $runtime Total runtime, including RTT
 988          */
 989         private function updateTrxWriteQueryTime( $sql, $runtime ) {
 990                 // Whether this is indicative of replica DB runtime (except for RBR or ws_repl)
 991                 $indicativeOfReplicaRuntime = true;
 992                 if ( $runtime > self::SLOW_WRITE_SEC ) {
 993                         $verb = $this->getQueryVerb( $sql );
 994                         // insert(), upsert(), replace() are fast unless bulky in size or blocked on locks
 995                         if ( $verb === 'INSERT' ) {
 996                                 $indicativeOfReplicaRuntime = $this->affectedRows() > self::SMALL_WRITE_ROWS;
 997                         } elseif ( $verb === 'REPLACE' ) {
 998                                 $indicativeOfReplicaRuntime = $this->affectedRows() > self::SMALL_WRITE_ROWS / 2;
 999                         }
1000                 }
1001
1002                 $this->mTrxWriteDuration += $runtime;
1003                 $this->mTrxWriteQueryCount += 1;
1004                 if ( $indicativeOfReplicaRuntime ) {
1005                         $this->mTrxWriteAdjDuration += $runtime;
1006                         $this->mTrxWriteAdjQueryCount += 1;
1007                 }
1008         }
1009
1010         private function canRecoverFromDisconnect( $sql, $priorWritesPending ) {
1011                 # Transaction dropped; this can mean lost writes, or REPEATABLE-READ snapshots.
1012                 # Dropped connections also mean that named locks are automatically released.
1013                 # Only allow error suppression in autocommit mode or when the lost transaction
1014                 # didn't matter anyway (aside from DBO_TRX snapshot loss).
1015                 if ( $this->mNamedLocksHeld ) {
1016                         return false; // possible critical section violation
1017                 } elseif ( $sql === 'COMMIT' ) {
1018                         return !$priorWritesPending; // nothing written anyway? (T127428)
1019                 } elseif ( $sql === 'ROLLBACK' ) {
1020                         return true; // transaction lost...which is also what was requested :)
1021                 } elseif ( $this->explicitTrxActive() ) {
1022                         return false; // don't drop atomocity
1023                 } elseif ( $priorWritesPending ) {
1024                         return false; // prior writes lost from implicit transaction
1025                 }
1026
1027                 return true;
1028         }
1029
1030         private function handleSessionLoss() {
1031                 $this->mTrxLevel = 0;
1032                 $this->mTrxIdleCallbacks = []; // T67263
1033                 $this->mTrxPreCommitCallbacks = []; // T67263
1034                 $this->mSessionTempTables = [];
1035                 $this->mNamedLocksHeld = [];
1036                 try {
1037                         // Handle callbacks in mTrxEndCallbacks
1038                         $this->runOnTransactionIdleCallbacks( self::TRIGGER_ROLLBACK );
1039                         $this->runTransactionListenerCallbacks( self::TRIGGER_ROLLBACK );
1040                         return null;
1041                 } catch ( Exception $e ) {
1042                         // Already logged; move on...
1043                         return $e;
1044                 }
1045         }
1046
1047         public function reportQueryError( $error, $errno, $sql, $fname, $tempIgnore = false ) {
1048                 if ( $this->ignoreErrors() || $tempIgnore ) {
1049                         $this->queryLogger->debug( "SQL ERROR (ignored): $error\n" );
1050                 } else {
1051                         $sql1line = mb_substr( str_replace( "\n", "\\n", $sql ), 0, 5 * 1024 );
1052                         $this->queryLogger->error(
1053                                 "{fname}\t{db_server}\t{errno}\t{error}\t{sql1line}",
1054                                 $this->getLogContext( [
1055                                         'method' => __METHOD__,
1056                                         'errno' => $errno,
1057                                         'error' => $error,
1058                                         'sql1line' => $sql1line,
1059                                         'fname' => $fname,
1060                                 ] )
1061                         );
1062                         $this->queryLogger->debug( "SQL ERROR: " . $error . "\n" );
1063                         throw new DBQueryError( $this, $error, $errno, $sql, $fname );
1064                 }
1065         }
1066
1067         public function freeResult( $res ) {
1068         }
1069
1070         public function selectField(
1071                 $table, $var, $cond = '', $fname = __METHOD__, $options = []
1072         ) {
1073                 if ( $var === '*' ) { // sanity
1074                         throw new DBUnexpectedError( $this, "Cannot use a * field: got '$var'" );
1075                 }
1076
1077                 if ( !is_array( $options ) ) {
1078                         $options = [ $options ];
1079                 }
1080
1081                 $options['LIMIT'] = 1;
1082
1083                 $res = $this->select( $table, $var, $cond, $fname, $options );
1084                 if ( $res === false || !$this->numRows( $res ) ) {
1085                         return false;
1086                 }
1087
1088                 $row = $this->fetchRow( $res );
1089
1090                 if ( $row !== false ) {
1091                         return reset( $row );
1092                 } else {
1093                         return false;
1094                 }
1095         }
1096
1097         public function selectFieldValues(
1098                 $table, $var, $cond = '', $fname = __METHOD__, $options = [], $join_conds = []
1099         ) {
1100                 if ( $var === '*' ) { // sanity
1101                         throw new DBUnexpectedError( $this, "Cannot use a * field" );
1102                 } elseif ( !is_string( $var ) ) { // sanity
1103                         throw new DBUnexpectedError( $this, "Cannot use an array of fields" );
1104                 }
1105
1106                 if ( !is_array( $options ) ) {
1107                         $options = [ $options ];
1108                 }
1109
1110                 $res = $this->select( $table, $var, $cond, $fname, $options, $join_conds );
1111                 if ( $res === false ) {
1112                         return false;
1113                 }
1114
1115                 $values = [];
1116                 foreach ( $res as $row ) {
1117                         $values[] = $row->$var;
1118                 }
1119
1120                 return $values;
1121         }
1122
1123         /**
1124          * Returns an optional USE INDEX clause to go after the table, and a
1125          * string to go at the end of the query.
1126          *
1127          * @param array $options Associative array of options to be turned into
1128          *   an SQL query, valid keys are listed in the function.
1129          * @return array
1130          * @see Database::select()
1131          */
1132         protected function makeSelectOptions( $options ) {
1133                 $preLimitTail = $postLimitTail = '';
1134                 $startOpts = '';
1135
1136                 $noKeyOptions = [];
1137
1138                 foreach ( $options as $key => $option ) {
1139                         if ( is_numeric( $key ) ) {
1140                                 $noKeyOptions[$option] = true;
1141                         }
1142                 }
1143
1144                 $preLimitTail .= $this->makeGroupByWithHaving( $options );
1145
1146                 $preLimitTail .= $this->makeOrderBy( $options );
1147
1148                 if ( isset( $noKeyOptions['FOR UPDATE'] ) ) {
1149                         $postLimitTail .= ' FOR UPDATE';
1150                 }
1151
1152                 if ( isset( $noKeyOptions['LOCK IN SHARE MODE'] ) ) {
1153                         $postLimitTail .= ' LOCK IN SHARE MODE';
1154                 }
1155
1156                 if ( isset( $noKeyOptions['DISTINCT'] ) || isset( $noKeyOptions['DISTINCTROW'] ) ) {
1157                         $startOpts .= 'DISTINCT';
1158                 }
1159
1160                 # Various MySQL extensions
1161                 if ( isset( $noKeyOptions['STRAIGHT_JOIN'] ) ) {
1162                         $startOpts .= ' /*! STRAIGHT_JOIN */';
1163                 }
1164
1165                 if ( isset( $noKeyOptions['HIGH_PRIORITY'] ) ) {
1166                         $startOpts .= ' HIGH_PRIORITY';
1167                 }
1168
1169                 if ( isset( $noKeyOptions['SQL_BIG_RESULT'] ) ) {
1170                         $startOpts .= ' SQL_BIG_RESULT';
1171                 }
1172
1173                 if ( isset( $noKeyOptions['SQL_BUFFER_RESULT'] ) ) {
1174                         $startOpts .= ' SQL_BUFFER_RESULT';
1175                 }
1176
1177                 if ( isset( $noKeyOptions['SQL_SMALL_RESULT'] ) ) {
1178                         $startOpts .= ' SQL_SMALL_RESULT';
1179                 }
1180
1181                 if ( isset( $noKeyOptions['SQL_CALC_FOUND_ROWS'] ) ) {
1182                         $startOpts .= ' SQL_CALC_FOUND_ROWS';
1183                 }
1184
1185                 if ( isset( $noKeyOptions['SQL_CACHE'] ) ) {
1186                         $startOpts .= ' SQL_CACHE';
1187                 }
1188
1189                 if ( isset( $noKeyOptions['SQL_NO_CACHE'] ) ) {
1190                         $startOpts .= ' SQL_NO_CACHE';
1191                 }
1192
1193                 if ( isset( $options['USE INDEX'] ) && is_string( $options['USE INDEX'] ) ) {
1194                         $useIndex = $this->useIndexClause( $options['USE INDEX'] );
1195                 } else {
1196                         $useIndex = '';
1197                 }
1198                 if ( isset( $options['IGNORE INDEX'] ) && is_string( $options['IGNORE INDEX'] ) ) {
1199                         $ignoreIndex = $this->ignoreIndexClause( $options['IGNORE INDEX'] );
1200                 } else {
1201                         $ignoreIndex = '';
1202                 }
1203
1204                 return [ $startOpts, $useIndex, $preLimitTail, $postLimitTail, $ignoreIndex ];
1205         }
1206
1207         /**
1208          * Returns an optional GROUP BY with an optional HAVING
1209          *
1210          * @param array $options Associative array of options
1211          * @return string
1212          * @see Database::select()
1213          * @since 1.21
1214          */
1215         protected function makeGroupByWithHaving( $options ) {
1216                 $sql = '';
1217                 if ( isset( $options['GROUP BY'] ) ) {
1218                         $gb = is_array( $options['GROUP BY'] )
1219                                 ? implode( ',', $options['GROUP BY'] )
1220                                 : $options['GROUP BY'];
1221                         $sql .= ' GROUP BY ' . $gb;
1222                 }
1223                 if ( isset( $options['HAVING'] ) ) {
1224                         $having = is_array( $options['HAVING'] )
1225                                 ? $this->makeList( $options['HAVING'], self::LIST_AND )
1226                                 : $options['HAVING'];
1227                         $sql .= ' HAVING ' . $having;
1228                 }
1229
1230                 return $sql;
1231         }
1232
1233         /**
1234          * Returns an optional ORDER BY
1235          *
1236          * @param array $options Associative array of options
1237          * @return string
1238          * @see Database::select()
1239          * @since 1.21
1240          */
1241         protected function makeOrderBy( $options ) {
1242                 if ( isset( $options['ORDER BY'] ) ) {
1243                         $ob = is_array( $options['ORDER BY'] )
1244                                 ? implode( ',', $options['ORDER BY'] )
1245                                 : $options['ORDER BY'];
1246
1247                         return ' ORDER BY ' . $ob;
1248                 }
1249
1250                 return '';
1251         }
1252
1253         public function select( $table, $vars, $conds = '', $fname = __METHOD__,
1254                 $options = [], $join_conds = [] ) {
1255                 $sql = $this->selectSQLText( $table, $vars, $conds, $fname, $options, $join_conds );
1256
1257                 return $this->query( $sql, $fname );
1258         }
1259
1260         public function selectSQLText( $table, $vars, $conds = '', $fname = __METHOD__,
1261                 $options = [], $join_conds = []
1262         ) {
1263                 if ( is_array( $vars ) ) {
1264                         $vars = implode( ',', $this->fieldNamesWithAlias( $vars ) );
1265                 }
1266
1267                 $options = (array)$options;
1268                 $useIndexes = ( isset( $options['USE INDEX'] ) && is_array( $options['USE INDEX'] ) )
1269                         ? $options['USE INDEX']
1270                         : [];
1271                 $ignoreIndexes = (
1272                         isset( $options['IGNORE INDEX'] ) &&
1273                         is_array( $options['IGNORE INDEX'] )
1274                 )
1275                         ? $options['IGNORE INDEX']
1276                         : [];
1277
1278                 if ( is_array( $table ) ) {
1279                         $from = ' FROM ' .
1280                                 $this->tableNamesWithIndexClauseOrJOIN(
1281                                         $table, $useIndexes, $ignoreIndexes, $join_conds );
1282                 } elseif ( $table != '' ) {
1283                         if ( $table[0] == ' ' ) {
1284                                 $from = ' FROM ' . $table;
1285                         } else {
1286                                 $from = ' FROM ' .
1287                                         $this->tableNamesWithIndexClauseOrJOIN(
1288                                                 [ $table ], $useIndexes, $ignoreIndexes, [] );
1289                         }
1290                 } else {
1291                         $from = '';
1292                 }
1293
1294                 list( $startOpts, $useIndex, $preLimitTail, $postLimitTail, $ignoreIndex ) =
1295                         $this->makeSelectOptions( $options );
1296
1297                 if ( !empty( $conds ) ) {
1298                         if ( is_array( $conds ) ) {
1299                                 $conds = $this->makeList( $conds, self::LIST_AND );
1300                         }
1301                         $sql = "SELECT $startOpts $vars $from $useIndex $ignoreIndex " .
1302                                 "WHERE $conds $preLimitTail";
1303                 } else {
1304                         $sql = "SELECT $startOpts $vars $from $useIndex $ignoreIndex $preLimitTail";
1305                 }
1306
1307                 if ( isset( $options['LIMIT'] ) ) {
1308                         $sql = $this->limitResult( $sql, $options['LIMIT'],
1309                                 isset( $options['OFFSET'] ) ? $options['OFFSET'] : false );
1310                 }
1311                 $sql = "$sql $postLimitTail";
1312
1313                 if ( isset( $options['EXPLAIN'] ) ) {
1314                         $sql = 'EXPLAIN ' . $sql;
1315                 }
1316
1317                 return $sql;
1318         }
1319
1320         public function selectRow( $table, $vars, $conds, $fname = __METHOD__,
1321                 $options = [], $join_conds = []
1322         ) {
1323                 $options = (array)$options;
1324                 $options['LIMIT'] = 1;
1325                 $res = $this->select( $table, $vars, $conds, $fname, $options, $join_conds );
1326
1327                 if ( $res === false ) {
1328                         return false;
1329                 }
1330
1331                 if ( !$this->numRows( $res ) ) {
1332                         return false;
1333                 }
1334
1335                 $obj = $this->fetchObject( $res );
1336
1337                 return $obj;
1338         }
1339
1340         public function estimateRowCount(
1341                 $table, $vars = '*', $conds = '', $fname = __METHOD__, $options = []
1342         ) {
1343                 $rows = 0;
1344                 $res = $this->select( $table, [ 'rowcount' => 'COUNT(*)' ], $conds, $fname, $options );
1345
1346                 if ( $res ) {
1347                         $row = $this->fetchRow( $res );
1348                         $rows = ( isset( $row['rowcount'] ) ) ? (int)$row['rowcount'] : 0;
1349                 }
1350
1351                 return $rows;
1352         }
1353
1354         public function selectRowCount(
1355                 $tables, $vars = '*', $conds = '', $fname = __METHOD__, $options = [], $join_conds = []
1356         ) {
1357                 $rows = 0;
1358                 $sql = $this->selectSQLText( $tables, '1', $conds, $fname, $options, $join_conds );
1359                 // The identifier quotes is primarily for MSSQL.
1360                 $rowCountCol = $this->addIdentifierQuotes( "rowcount" );
1361                 $tableName = $this->addIdentifierQuotes( "tmp_count" );
1362                 $res = $this->query( "SELECT COUNT(*) AS $rowCountCol FROM ($sql) $tableName", $fname );
1363
1364                 if ( $res ) {
1365                         $row = $this->fetchRow( $res );
1366                         $rows = ( isset( $row['rowcount'] ) ) ? (int)$row['rowcount'] : 0;
1367                 }
1368
1369                 return $rows;
1370         }
1371
1372         /**
1373          * Removes most variables from an SQL query and replaces them with X or N for numbers.
1374          * It's only slightly flawed. Don't use for anything important.
1375          *
1376          * @param string $sql A SQL Query
1377          *
1378          * @return string
1379          */
1380         protected static function generalizeSQL( $sql ) {
1381                 # This does the same as the regexp below would do, but in such a way
1382                 # as to avoid crashing php on some large strings.
1383                 # $sql = preg_replace( "/'([^\\\\']|\\\\.)*'|\"([^\\\\\"]|\\\\.)*\"/", "'X'", $sql );
1384
1385                 $sql = str_replace( "\\\\", '', $sql );
1386                 $sql = str_replace( "\\'", '', $sql );
1387                 $sql = str_replace( "\\\"", '', $sql );
1388                 $sql = preg_replace( "/'.*'/s", "'X'", $sql );
1389                 $sql = preg_replace( '/".*"/s', "'X'", $sql );
1390
1391                 # All newlines, tabs, etc replaced by single space
1392                 $sql = preg_replace( '/\s+/', ' ', $sql );
1393
1394                 # All numbers => N,
1395                 # except the ones surrounded by characters, e.g. l10n
1396                 $sql = preg_replace( '/-?\d+(,-?\d+)+/s', 'N,...,N', $sql );
1397                 $sql = preg_replace( '/(?<![a-zA-Z])-?\d+(?![a-zA-Z])/s', 'N', $sql );
1398
1399                 return $sql;
1400         }
1401
1402         public function fieldExists( $table, $field, $fname = __METHOD__ ) {
1403                 $info = $this->fieldInfo( $table, $field );
1404
1405                 return (bool)$info;
1406         }
1407
1408         public function indexExists( $table, $index, $fname = __METHOD__ ) {
1409                 if ( !$this->tableExists( $table ) ) {
1410                         return null;
1411                 }
1412
1413                 $info = $this->indexInfo( $table, $index, $fname );
1414                 if ( is_null( $info ) ) {
1415                         return null;
1416                 } else {
1417                         return $info !== false;
1418                 }
1419         }
1420
1421         public function tableExists( $table, $fname = __METHOD__ ) {
1422                 $tableRaw = $this->tableName( $table, 'raw' );
1423                 if ( isset( $this->mSessionTempTables[$tableRaw] ) ) {
1424                         return true; // already known to exist
1425                 }
1426
1427                 $table = $this->tableName( $table );
1428                 $ignoreErrors = true;
1429                 $res = $this->query( "SELECT 1 FROM $table LIMIT 1", $fname, $ignoreErrors );
1430
1431                 return (bool)$res;
1432         }
1433
1434         public function indexUnique( $table, $index ) {
1435                 $indexInfo = $this->indexInfo( $table, $index );
1436
1437                 if ( !$indexInfo ) {
1438                         return null;
1439                 }
1440
1441                 return !$indexInfo[0]->Non_unique;
1442         }
1443
1444         /**
1445          * Helper for Database::insert().
1446          *
1447          * @param array $options
1448          * @return string
1449          */
1450         protected function makeInsertOptions( $options ) {
1451                 return implode( ' ', $options );
1452         }
1453
1454         public function insert( $table, $a, $fname = __METHOD__, $options = [] ) {
1455                 # No rows to insert, easy just return now
1456                 if ( !count( $a ) ) {
1457                         return true;
1458                 }
1459
1460                 $table = $this->tableName( $table );
1461
1462                 if ( !is_array( $options ) ) {
1463                         $options = [ $options ];
1464                 }
1465
1466                 $fh = null;
1467                 if ( isset( $options['fileHandle'] ) ) {
1468                         $fh = $options['fileHandle'];
1469                 }
1470                 $options = $this->makeInsertOptions( $options );
1471
1472                 if ( isset( $a[0] ) && is_array( $a[0] ) ) {
1473                         $multi = true;
1474                         $keys = array_keys( $a[0] );
1475                 } else {
1476                         $multi = false;
1477                         $keys = array_keys( $a );
1478                 }
1479
1480                 $sql = 'INSERT ' . $options .
1481                         " INTO $table (" . implode( ',', $keys ) . ') VALUES ';
1482
1483                 if ( $multi ) {
1484                         $first = true;
1485                         foreach ( $a as $row ) {
1486                                 if ( $first ) {
1487                                         $first = false;
1488                                 } else {
1489                                         $sql .= ',';
1490                                 }
1491                                 $sql .= '(' . $this->makeList( $row ) . ')';
1492                         }
1493                 } else {
1494                         $sql .= '(' . $this->makeList( $a ) . ')';
1495                 }
1496
1497                 if ( $fh !== null && false === fwrite( $fh, $sql ) ) {
1498                         return false;
1499                 } elseif ( $fh !== null ) {
1500                         return true;
1501                 }
1502
1503                 return (bool)$this->query( $sql, $fname );
1504         }
1505
1506         /**
1507          * Make UPDATE options array for Database::makeUpdateOptions
1508          *
1509          * @param array $options
1510          * @return array
1511          */
1512         protected function makeUpdateOptionsArray( $options ) {
1513                 if ( !is_array( $options ) ) {
1514                         $options = [ $options ];
1515                 }
1516
1517                 $opts = [];
1518
1519                 if ( in_array( 'IGNORE', $options ) ) {
1520                         $opts[] = 'IGNORE';
1521                 }
1522
1523                 return $opts;
1524         }
1525
1526         /**
1527          * Make UPDATE options for the Database::update function
1528          *
1529          * @param array $options The options passed to Database::update
1530          * @return string
1531          */
1532         protected function makeUpdateOptions( $options ) {
1533                 $opts = $this->makeUpdateOptionsArray( $options );
1534
1535                 return implode( ' ', $opts );
1536         }
1537
1538         public function update( $table, $values, $conds, $fname = __METHOD__, $options = [] ) {
1539                 $table = $this->tableName( $table );
1540                 $opts = $this->makeUpdateOptions( $options );
1541                 $sql = "UPDATE $opts $table SET " . $this->makeList( $values, self::LIST_SET );
1542
1543                 if ( $conds !== [] && $conds !== '*' ) {
1544                         $sql .= " WHERE " . $this->makeList( $conds, self::LIST_AND );
1545                 }
1546
1547                 return (bool)$this->query( $sql, $fname );
1548         }
1549
1550         public function makeList( $a, $mode = self::LIST_COMMA ) {
1551                 if ( !is_array( $a ) ) {
1552                         throw new DBUnexpectedError( $this, __METHOD__ . ' called with incorrect parameters' );
1553                 }
1554
1555                 $first = true;
1556                 $list = '';
1557
1558                 foreach ( $a as $field => $value ) {
1559                         if ( !$first ) {
1560                                 if ( $mode == self::LIST_AND ) {
1561                                         $list .= ' AND ';
1562                                 } elseif ( $mode == self::LIST_OR ) {
1563                                         $list .= ' OR ';
1564                                 } else {
1565                                         $list .= ',';
1566                                 }
1567                         } else {
1568                                 $first = false;
1569                         }
1570
1571                         if ( ( $mode == self::LIST_AND || $mode == self::LIST_OR ) && is_numeric( $field ) ) {
1572                                 $list .= "($value)";
1573                         } elseif ( $mode == self::LIST_SET && is_numeric( $field ) ) {
1574                                 $list .= "$value";
1575                         } elseif (
1576                                 ( $mode == self::LIST_AND || $mode == self::LIST_OR ) && is_array( $value )
1577                         ) {
1578                                 // Remove null from array to be handled separately if found
1579                                 $includeNull = false;
1580                                 foreach ( array_keys( $value, null, true ) as $nullKey ) {
1581                                         $includeNull = true;
1582                                         unset( $value[$nullKey] );
1583                                 }
1584                                 if ( count( $value ) == 0 && !$includeNull ) {
1585                                         throw new InvalidArgumentException(
1586                                                 __METHOD__ . ": empty input for field $field" );
1587                                 } elseif ( count( $value ) == 0 ) {
1588                                         // only check if $field is null
1589                                         $list .= "$field IS NULL";
1590                                 } else {
1591                                         // IN clause contains at least one valid element
1592                                         if ( $includeNull ) {
1593                                                 // Group subconditions to ensure correct precedence
1594                                                 $list .= '(';
1595                                         }
1596                                         if ( count( $value ) == 1 ) {
1597                                                 // Special-case single values, as IN isn't terribly efficient
1598                                                 // Don't necessarily assume the single key is 0; we don't
1599                                                 // enforce linear numeric ordering on other arrays here.
1600                                                 $value = array_values( $value )[0];
1601                                                 $list .= $field . " = " . $this->addQuotes( $value );
1602                                         } else {
1603                                                 $list .= $field . " IN (" . $this->makeList( $value ) . ") ";
1604                                         }
1605                                         // if null present in array, append IS NULL
1606                                         if ( $includeNull ) {
1607                                                 $list .= " OR $field IS NULL)";
1608                                         }
1609                                 }
1610                         } elseif ( $value === null ) {
1611                                 if ( $mode == self::LIST_AND || $mode == self::LIST_OR ) {
1612                                         $list .= "$field IS ";
1613                                 } elseif ( $mode == self::LIST_SET ) {
1614                                         $list .= "$field = ";
1615                                 }
1616                                 $list .= 'NULL';
1617                         } else {
1618                                 if (
1619                                         $mode == self::LIST_AND || $mode == self::LIST_OR || $mode == self::LIST_SET
1620                                 ) {
1621                                         $list .= "$field = ";
1622                                 }
1623                                 $list .= $mode == self::LIST_NAMES ? $value : $this->addQuotes( $value );
1624                         }
1625                 }
1626
1627                 return $list;
1628         }
1629
1630         public function makeWhereFrom2d( $data, $baseKey, $subKey ) {
1631                 $conds = [];
1632
1633                 foreach ( $data as $base => $sub ) {
1634                         if ( count( $sub ) ) {
1635                                 $conds[] = $this->makeList(
1636                                         [ $baseKey => $base, $subKey => array_keys( $sub ) ],
1637                                         self::LIST_AND );
1638                         }
1639                 }
1640
1641                 if ( $conds ) {
1642                         return $this->makeList( $conds, self::LIST_OR );
1643                 } else {
1644                         // Nothing to search for...
1645                         return false;
1646                 }
1647         }
1648
1649         public function aggregateValue( $valuedata, $valuename = 'value' ) {
1650                 return $valuename;
1651         }
1652
1653         public function bitNot( $field ) {
1654                 return "(~$field)";
1655         }
1656
1657         public function bitAnd( $fieldLeft, $fieldRight ) {
1658                 return "($fieldLeft & $fieldRight)";
1659         }
1660
1661         public function bitOr( $fieldLeft, $fieldRight ) {
1662                 return "($fieldLeft | $fieldRight)";
1663         }
1664
1665         public function buildConcat( $stringList ) {
1666                 return 'CONCAT(' . implode( ',', $stringList ) . ')';
1667         }
1668
1669         public function buildGroupConcatField(
1670                 $delim, $table, $field, $conds = '', $join_conds = []
1671         ) {
1672                 $fld = "GROUP_CONCAT($field SEPARATOR " . $this->addQuotes( $delim ) . ')';
1673
1674                 return '(' . $this->selectSQLText( $table, $fld, $conds, null, [], $join_conds ) . ')';
1675         }
1676
1677         public function buildStringCast( $field ) {
1678                 return $field;
1679         }
1680
1681         public function selectDB( $db ) {
1682                 # Stub. Shouldn't cause serious problems if it's not overridden, but
1683                 # if your database engine supports a concept similar to MySQL's
1684                 # databases you may as well.
1685                 $this->mDBname = $db;
1686
1687                 return true;
1688         }
1689
1690         public function getDBname() {
1691                 return $this->mDBname;
1692         }
1693
1694         public function getServer() {
1695                 return $this->mServer;
1696         }
1697
1698         public function tableName( $name, $format = 'quoted' ) {
1699                 # Skip the entire process when we have a string quoted on both ends.
1700                 # Note that we check the end so that we will still quote any use of
1701                 # use of `database`.table. But won't break things if someone wants
1702                 # to query a database table with a dot in the name.
1703                 if ( $this->isQuotedIdentifier( $name ) ) {
1704                         return $name;
1705                 }
1706
1707                 # Lets test for any bits of text that should never show up in a table
1708                 # name. Basically anything like JOIN or ON which are actually part of
1709                 # SQL queries, but may end up inside of the table value to combine
1710                 # sql. Such as how the API is doing.
1711                 # Note that we use a whitespace test rather than a \b test to avoid
1712                 # any remote case where a word like on may be inside of a table name
1713                 # surrounded by symbols which may be considered word breaks.
1714                 if ( preg_match( '/(^|\s)(DISTINCT|JOIN|ON|AS)(\s|$)/i', $name ) !== 0 ) {
1715                         return $name;
1716                 }
1717
1718                 # Split database and table into proper variables.
1719                 # We reverse the explode so that database.table and table both output
1720                 # the correct table.
1721                 $dbDetails = explode( '.', $name, 3 );
1722                 if ( count( $dbDetails ) == 3 ) {
1723                         list( $database, $schema, $table ) = $dbDetails;
1724                         # We don't want any prefix added in this case
1725                         $prefix = '';
1726                 } elseif ( count( $dbDetails ) == 2 ) {
1727                         list( $database, $table ) = $dbDetails;
1728                         # We don't want any prefix added in this case
1729                         $prefix = '';
1730                         # In dbs that support it, $database may actually be the schema
1731                         # but that doesn't affect any of the functionality here
1732                         $schema = '';
1733                 } else {
1734                         list( $table ) = $dbDetails;
1735                         if ( isset( $this->tableAliases[$table] ) ) {
1736                                 $database = $this->tableAliases[$table]['dbname'];
1737                                 $schema = is_string( $this->tableAliases[$table]['schema'] )
1738                                         ? $this->tableAliases[$table]['schema']
1739                                         : $this->mSchema;
1740                                 $prefix = is_string( $this->tableAliases[$table]['prefix'] )
1741                                         ? $this->tableAliases[$table]['prefix']
1742                                         : $this->mTablePrefix;
1743                         } else {
1744                                 $database = '';
1745                                 $schema = $this->mSchema; # Default schema
1746                                 $prefix = $this->mTablePrefix; # Default prefix
1747                         }
1748                 }
1749
1750                 # Quote $table and apply the prefix if not quoted.
1751                 # $tableName might be empty if this is called from Database::replaceVars()
1752                 $tableName = "{$prefix}{$table}";
1753                 if ( $format === 'quoted'
1754                         && !$this->isQuotedIdentifier( $tableName )
1755                         && $tableName !== ''
1756                 ) {
1757                         $tableName = $this->addIdentifierQuotes( $tableName );
1758                 }
1759
1760                 # Quote $schema and $database and merge them with the table name if needed
1761                 $tableName = $this->prependDatabaseOrSchema( $schema, $tableName, $format );
1762                 $tableName = $this->prependDatabaseOrSchema( $database, $tableName, $format );
1763
1764                 return $tableName;
1765         }
1766
1767         /**
1768          * @param string|null $namespace Database or schema
1769          * @param string $relation Name of table, view, sequence, etc...
1770          * @param string $format One of (raw, quoted)
1771          * @return string Relation name with quoted and merged $namespace as needed
1772          */
1773         private function prependDatabaseOrSchema( $namespace, $relation, $format ) {
1774                 if ( strlen( $namespace ) ) {
1775                         if ( $format === 'quoted' && !$this->isQuotedIdentifier( $namespace ) ) {
1776                                 $namespace = $this->addIdentifierQuotes( $namespace );
1777                         }
1778                         $relation = $namespace . '.' . $relation;
1779                 }
1780
1781                 return $relation;
1782         }
1783
1784         public function tableNames() {
1785                 $inArray = func_get_args();
1786                 $retVal = [];
1787
1788                 foreach ( $inArray as $name ) {
1789                         $retVal[$name] = $this->tableName( $name );
1790                 }
1791
1792                 return $retVal;
1793         }
1794
1795         public function tableNamesN() {
1796                 $inArray = func_get_args();
1797                 $retVal = [];
1798
1799                 foreach ( $inArray as $name ) {
1800                         $retVal[] = $this->tableName( $name );
1801                 }
1802
1803                 return $retVal;
1804         }
1805
1806         /**
1807          * Get an aliased table name
1808          * e.g. tableName AS newTableName
1809          *
1810          * @param string $name Table name, see tableName()
1811          * @param string|bool $alias Alias (optional)
1812          * @return string SQL name for aliased table. Will not alias a table to its own name
1813          */
1814         protected function tableNameWithAlias( $name, $alias = false ) {
1815                 if ( !$alias || $alias == $name ) {
1816                         return $this->tableName( $name );
1817                 } else {
1818                         return $this->tableName( $name ) . ' ' . $this->addIdentifierQuotes( $alias );
1819                 }
1820         }
1821
1822         /**
1823          * Gets an array of aliased table names
1824          *
1825          * @param array $tables [ [alias] => table ]
1826          * @return string[] See tableNameWithAlias()
1827          */
1828         protected function tableNamesWithAlias( $tables ) {
1829                 $retval = [];
1830                 foreach ( $tables as $alias => $table ) {
1831                         if ( is_numeric( $alias ) ) {
1832                                 $alias = $table;
1833                         }
1834                         $retval[] = $this->tableNameWithAlias( $table, $alias );
1835                 }
1836
1837                 return $retval;
1838         }
1839
1840         /**
1841          * Get an aliased field name
1842          * e.g. fieldName AS newFieldName
1843          *
1844          * @param string $name Field name
1845          * @param string|bool $alias Alias (optional)
1846          * @return string SQL name for aliased field. Will not alias a field to its own name
1847          */
1848         protected function fieldNameWithAlias( $name, $alias = false ) {
1849                 if ( !$alias || (string)$alias === (string)$name ) {
1850                         return $name;
1851                 } else {
1852                         return $name . ' AS ' . $this->addIdentifierQuotes( $alias ); // PostgreSQL needs AS
1853                 }
1854         }
1855
1856         /**
1857          * Gets an array of aliased field names
1858          *
1859          * @param array $fields [ [alias] => field ]
1860          * @return string[] See fieldNameWithAlias()
1861          */
1862         protected function fieldNamesWithAlias( $fields ) {
1863                 $retval = [];
1864                 foreach ( $fields as $alias => $field ) {
1865                         if ( is_numeric( $alias ) ) {
1866                                 $alias = $field;
1867                         }
1868                         $retval[] = $this->fieldNameWithAlias( $field, $alias );
1869                 }
1870
1871                 return $retval;
1872         }
1873
1874         /**
1875          * Get the aliased table name clause for a FROM clause
1876          * which might have a JOIN and/or USE INDEX or IGNORE INDEX clause
1877          *
1878          * @param array $tables ( [alias] => table )
1879          * @param array $use_index Same as for select()
1880          * @param array $ignore_index Same as for select()
1881          * @param array $join_conds Same as for select()
1882          * @return string
1883          */
1884         protected function tableNamesWithIndexClauseOrJOIN(
1885                 $tables, $use_index = [], $ignore_index = [], $join_conds = []
1886         ) {
1887                 $ret = [];
1888                 $retJOIN = [];
1889                 $use_index = (array)$use_index;
1890                 $ignore_index = (array)$ignore_index;
1891                 $join_conds = (array)$join_conds;
1892
1893                 foreach ( $tables as $alias => $table ) {
1894                         if ( !is_string( $alias ) ) {
1895                                 // No alias? Set it equal to the table name
1896                                 $alias = $table;
1897                         }
1898                         // Is there a JOIN clause for this table?
1899                         if ( isset( $join_conds[$alias] ) ) {
1900                                 list( $joinType, $conds ) = $join_conds[$alias];
1901                                 $tableClause = $joinType;
1902                                 $tableClause .= ' ' . $this->tableNameWithAlias( $table, $alias );
1903                                 if ( isset( $use_index[$alias] ) ) { // has USE INDEX?
1904                                         $use = $this->useIndexClause( implode( ',', (array)$use_index[$alias] ) );
1905                                         if ( $use != '' ) {
1906                                                 $tableClause .= ' ' . $use;
1907                                         }
1908                                 }
1909                                 if ( isset( $ignore_index[$alias] ) ) { // has IGNORE INDEX?
1910                                         $ignore = $this->ignoreIndexClause(
1911                                                 implode( ',', (array)$ignore_index[$alias] ) );
1912                                         if ( $ignore != '' ) {
1913                                                 $tableClause .= ' ' . $ignore;
1914                                         }
1915                                 }
1916                                 $on = $this->makeList( (array)$conds, self::LIST_AND );
1917                                 if ( $on != '' ) {
1918                                         $tableClause .= ' ON (' . $on . ')';
1919                                 }
1920
1921                                 $retJOIN[] = $tableClause;
1922                         } elseif ( isset( $use_index[$alias] ) ) {
1923                                 // Is there an INDEX clause for this table?
1924                                 $tableClause = $this->tableNameWithAlias( $table, $alias );
1925                                 $tableClause .= ' ' . $this->useIndexClause(
1926                                                 implode( ',', (array)$use_index[$alias] )
1927                                         );
1928
1929                                 $ret[] = $tableClause;
1930                         } elseif ( isset( $ignore_index[$alias] ) ) {
1931                                 // Is there an INDEX clause for this table?
1932                                 $tableClause = $this->tableNameWithAlias( $table, $alias );
1933                                 $tableClause .= ' ' . $this->ignoreIndexClause(
1934                                                 implode( ',', (array)$ignore_index[$alias] )
1935                                         );
1936
1937                                 $ret[] = $tableClause;
1938                         } else {
1939                                 $tableClause = $this->tableNameWithAlias( $table, $alias );
1940
1941                                 $ret[] = $tableClause;
1942                         }
1943                 }
1944
1945                 // We can't separate explicit JOIN clauses with ',', use ' ' for those
1946                 $implicitJoins = !empty( $ret ) ? implode( ',', $ret ) : "";
1947                 $explicitJoins = !empty( $retJOIN ) ? implode( ' ', $retJOIN ) : "";
1948
1949                 // Compile our final table clause
1950                 return implode( ' ', [ $implicitJoins, $explicitJoins ] );
1951         }
1952
1953         /**
1954          * Allows for index remapping in queries where this is not consistent across DBMS
1955          *
1956          * @param string $index
1957          * @return string
1958          */
1959         protected function indexName( $index ) {
1960                 return $index;
1961         }
1962
1963         public function addQuotes( $s ) {
1964                 if ( $s instanceof Blob ) {
1965                         $s = $s->fetch();
1966                 }
1967                 if ( $s === null ) {
1968                         return 'NULL';
1969                 } elseif ( is_bool( $s ) ) {
1970                         return (int)$s;
1971                 } else {
1972                         # This will also quote numeric values. This should be harmless,
1973                         # and protects against weird problems that occur when they really
1974                         # _are_ strings such as article titles and string->number->string
1975                         # conversion is not 1:1.
1976                         return "'" . $this->strencode( $s ) . "'";
1977                 }
1978         }
1979
1980         /**
1981          * Quotes an identifier using `backticks` or "double quotes" depending on the database type.
1982          * MySQL uses `backticks` while basically everything else uses double quotes.
1983          * Since MySQL is the odd one out here the double quotes are our generic
1984          * and we implement backticks in DatabaseMysql.
1985          *
1986          * @param string $s
1987          * @return string
1988          */
1989         public function addIdentifierQuotes( $s ) {
1990                 return '"' . str_replace( '"', '""', $s ) . '"';
1991         }
1992
1993         /**
1994          * Returns if the given identifier looks quoted or not according to
1995          * the database convention for quoting identifiers .
1996          *
1997          * @note Do not use this to determine if untrusted input is safe.
1998          *   A malicious user can trick this function.
1999          * @param string $name
2000          * @return bool
2001          */
2002         public function isQuotedIdentifier( $name ) {
2003                 return $name[0] == '"' && substr( $name, -1, 1 ) == '"';
2004         }
2005
2006         /**
2007          * @param string $s
2008          * @return string
2009          */
2010         protected function escapeLikeInternal( $s ) {
2011                 return addcslashes( $s, '\%_' );
2012         }
2013
2014         public function buildLike() {
2015                 $params = func_get_args();
2016
2017                 if ( count( $params ) > 0 && is_array( $params[0] ) ) {
2018                         $params = $params[0];
2019                 }
2020
2021                 $s = '';
2022
2023                 foreach ( $params as $value ) {
2024                         if ( $value instanceof LikeMatch ) {
2025                                 $s .= $value->toString();
2026                         } else {
2027                                 $s .= $this->escapeLikeInternal( $value );
2028                         }
2029                 }
2030
2031                 return " LIKE {$this->addQuotes( $s )} ";
2032         }
2033
2034         public function anyChar() {
2035                 return new LikeMatch( '_' );
2036         }
2037
2038         public function anyString() {
2039                 return new LikeMatch( '%' );
2040         }
2041
2042         public function nextSequenceValue( $seqName ) {
2043                 return null;
2044         }
2045
2046         /**
2047          * USE INDEX clause. Unlikely to be useful for anything but MySQL. This
2048          * is only needed because a) MySQL must be as efficient as possible due to
2049          * its use on Wikipedia, and b) MySQL 4.0 is kind of dumb sometimes about
2050          * which index to pick. Anyway, other databases might have different
2051          * indexes on a given table. So don't bother overriding this unless you're
2052          * MySQL.
2053          * @param string $index
2054          * @return string
2055          */
2056         public function useIndexClause( $index ) {
2057                 return '';
2058         }
2059
2060         /**
2061          * IGNORE INDEX clause. Unlikely to be useful for anything but MySQL. This
2062          * is only needed because a) MySQL must be as efficient as possible due to
2063          * its use on Wikipedia, and b) MySQL 4.0 is kind of dumb sometimes about
2064          * which index to pick. Anyway, other databases might have different
2065          * indexes on a given table. So don't bother overriding this unless you're
2066          * MySQL.
2067          * @param string $index
2068          * @return string
2069          */
2070         public function ignoreIndexClause( $index ) {
2071                 return '';
2072         }
2073
2074         public function replace( $table, $uniqueIndexes, $rows, $fname = __METHOD__ ) {
2075                 $quotedTable = $this->tableName( $table );
2076
2077                 if ( count( $rows ) == 0 ) {
2078                         return;
2079                 }
2080
2081                 # Single row case
2082                 if ( !is_array( reset( $rows ) ) ) {
2083                         $rows = [ $rows ];
2084                 }
2085
2086                 // @FXIME: this is not atomic, but a trx would break affectedRows()
2087                 foreach ( $rows as $row ) {
2088                         # Delete rows which collide
2089                         if ( $uniqueIndexes ) {
2090                                 $sql = "DELETE FROM $quotedTable WHERE ";
2091                                 $first = true;
2092                                 foreach ( $uniqueIndexes as $index ) {
2093                                         if ( $first ) {
2094                                                 $first = false;
2095                                                 $sql .= '( ';
2096                                         } else {
2097                                                 $sql .= ' ) OR ( ';
2098                                         }
2099                                         if ( is_array( $index ) ) {
2100                                                 $first2 = true;
2101                                                 foreach ( $index as $col ) {
2102                                                         if ( $first2 ) {
2103                                                                 $first2 = false;
2104                                                         } else {
2105                                                                 $sql .= ' AND ';
2106                                                         }
2107                                                         $sql .= $col . '=' . $this->addQuotes( $row[$col] );
2108                                                 }
2109                                         } else {
2110                                                 $sql .= $index . '=' . $this->addQuotes( $row[$index] );
2111                                         }
2112                                 }
2113                                 $sql .= ' )';
2114                                 $this->query( $sql, $fname );
2115                         }
2116
2117                         # Now insert the row
2118                         $this->insert( $table, $row, $fname );
2119                 }
2120         }
2121
2122         /**
2123          * REPLACE query wrapper for MySQL and SQLite, which have a native REPLACE
2124          * statement.
2125          *
2126          * @param string $table Table name
2127          * @param array|string $rows Row(s) to insert
2128          * @param string $fname Caller function name
2129          *
2130          * @return ResultWrapper
2131          */
2132         protected function nativeReplace( $table, $rows, $fname ) {
2133                 $table = $this->tableName( $table );
2134
2135                 # Single row case
2136                 if ( !is_array( reset( $rows ) ) ) {
2137                         $rows = [ $rows ];
2138                 }
2139
2140                 $sql = "REPLACE INTO $table (" . implode( ',', array_keys( $rows[0] ) ) . ') VALUES ';
2141                 $first = true;
2142
2143                 foreach ( $rows as $row ) {
2144                         if ( $first ) {
2145                                 $first = false;
2146                         } else {
2147                                 $sql .= ',';
2148                         }
2149
2150                         $sql .= '(' . $this->makeList( $row ) . ')';
2151                 }
2152
2153                 return $this->query( $sql, $fname );
2154         }
2155
2156         public function upsert( $table, array $rows, array $uniqueIndexes, array $set,
2157                 $fname = __METHOD__
2158         ) {
2159                 if ( !count( $rows ) ) {
2160                         return true; // nothing to do
2161                 }
2162
2163                 if ( !is_array( reset( $rows ) ) ) {
2164                         $rows = [ $rows ];
2165                 }
2166
2167                 if ( count( $uniqueIndexes ) ) {
2168                         $clauses = []; // list WHERE clauses that each identify a single row
2169                         foreach ( $rows as $row ) {
2170                                 foreach ( $uniqueIndexes as $index ) {
2171                                         $index = is_array( $index ) ? $index : [ $index ]; // columns
2172                                         $rowKey = []; // unique key to this row
2173                                         foreach ( $index as $column ) {
2174                                                 $rowKey[$column] = $row[$column];
2175                                         }
2176                                         $clauses[] = $this->makeList( $rowKey, self::LIST_AND );
2177                                 }
2178                         }
2179                         $where = [ $this->makeList( $clauses, self::LIST_OR ) ];
2180                 } else {
2181                         $where = false;
2182                 }
2183
2184                 $useTrx = !$this->mTrxLevel;
2185                 if ( $useTrx ) {
2186                         $this->begin( $fname, self::TRANSACTION_INTERNAL );
2187                 }
2188                 try {
2189                         # Update any existing conflicting row(s)
2190                         if ( $where !== false ) {
2191                                 $ok = $this->update( $table, $set, $where, $fname );
2192                         } else {
2193                                 $ok = true;
2194                         }
2195                         # Now insert any non-conflicting row(s)
2196                         $ok = $this->insert( $table, $rows, $fname, [ 'IGNORE' ] ) && $ok;
2197                 } catch ( Exception $e ) {
2198                         if ( $useTrx ) {
2199                                 $this->rollback( $fname, self::FLUSHING_INTERNAL );
2200                         }
2201                         throw $e;
2202                 }
2203                 if ( $useTrx ) {
2204                         $this->commit( $fname, self::FLUSHING_INTERNAL );
2205                 }
2206
2207                 return $ok;
2208         }
2209
2210         public function deleteJoin( $delTable, $joinTable, $delVar, $joinVar, $conds,
2211                 $fname = __METHOD__
2212         ) {
2213                 if ( !$conds ) {
2214                         throw new DBUnexpectedError( $this, __METHOD__ . ' called with empty $conds' );
2215                 }
2216
2217                 $delTable = $this->tableName( $delTable );
2218                 $joinTable = $this->tableName( $joinTable );
2219                 $sql = "DELETE FROM $delTable WHERE $delVar IN (SELECT $joinVar FROM $joinTable ";
2220                 if ( $conds != '*' ) {
2221                         $sql .= 'WHERE ' . $this->makeList( $conds, self::LIST_AND );
2222                 }
2223                 $sql .= ')';
2224
2225                 $this->query( $sql, $fname );
2226         }
2227
2228         public function textFieldSize( $table, $field ) {
2229                 $table = $this->tableName( $table );
2230                 $sql = "SHOW COLUMNS FROM $table LIKE \"$field\";";
2231                 $res = $this->query( $sql, __METHOD__ );
2232                 $row = $this->fetchObject( $res );
2233
2234                 $m = [];
2235
2236                 if ( preg_match( '/\((.*)\)/', $row->Type, $m ) ) {
2237                         $size = $m[1];
2238                 } else {
2239                         $size = -1;
2240                 }
2241
2242                 return $size;
2243         }
2244
2245         public function delete( $table, $conds, $fname = __METHOD__ ) {
2246                 if ( !$conds ) {
2247                         throw new DBUnexpectedError( $this, __METHOD__ . ' called with no conditions' );
2248                 }
2249
2250                 $table = $this->tableName( $table );
2251                 $sql = "DELETE FROM $table";
2252
2253                 if ( $conds != '*' ) {
2254                         if ( is_array( $conds ) ) {
2255                                 $conds = $this->makeList( $conds, self::LIST_AND );
2256                         }
2257                         $sql .= ' WHERE ' . $conds;
2258                 }
2259
2260                 return $this->query( $sql, $fname );
2261         }
2262
2263         public function insertSelect(
2264                 $destTable, $srcTable, $varMap, $conds,
2265                 $fname = __METHOD__, $insertOptions = [], $selectOptions = []
2266         ) {
2267                 if ( $this->cliMode ) {
2268                         // For massive migrations with downtime, we don't want to select everything
2269                         // into memory and OOM, so do all this native on the server side if possible.
2270                         return $this->nativeInsertSelect(
2271                                 $destTable,
2272                                 $srcTable,
2273                                 $varMap,
2274                                 $conds,
2275                                 $fname,
2276                                 $insertOptions,
2277                                 $selectOptions
2278                         );
2279                 }
2280
2281                 // For web requests, do a locking SELECT and then INSERT. This puts the SELECT burden
2282                 // on only the master (without needing row-based-replication). It also makes it easy to
2283                 // know how big the INSERT is going to be.
2284                 $fields = [];
2285                 foreach ( $varMap as $dstColumn => $sourceColumnOrSql ) {
2286                         $fields[] = $this->fieldNameWithAlias( $sourceColumnOrSql, $dstColumn );
2287                 }
2288                 $selectOptions[] = 'FOR UPDATE';
2289                 $res = $this->select( $srcTable, implode( ',', $fields ), $conds, $fname, $selectOptions );
2290                 if ( !$res ) {
2291                         return false;
2292                 }
2293
2294                 $rows = [];
2295                 foreach ( $res as $row ) {
2296                         $rows[] = (array)$row;
2297                 }
2298
2299                 return $this->insert( $destTable, $rows, $fname, $insertOptions );
2300         }
2301
2302         protected function nativeInsertSelect( $destTable, $srcTable, $varMap, $conds,
2303                 $fname = __METHOD__,
2304                 $insertOptions = [], $selectOptions = []
2305         ) {
2306                 $destTable = $this->tableName( $destTable );
2307
2308                 if ( !is_array( $insertOptions ) ) {
2309                         $insertOptions = [ $insertOptions ];
2310                 }
2311
2312                 $insertOptions = $this->makeInsertOptions( $insertOptions );
2313
2314                 if ( !is_array( $selectOptions ) ) {
2315                         $selectOptions = [ $selectOptions ];
2316                 }
2317
2318                 list( $startOpts, $useIndex, $tailOpts, $ignoreIndex ) = $this->makeSelectOptions(
2319                         $selectOptions );
2320
2321                 if ( is_array( $srcTable ) ) {
2322                         $srcTable = implode( ',', array_map( [ $this, 'tableName' ], $srcTable ) );
2323                 } else {
2324                         $srcTable = $this->tableName( $srcTable );
2325                 }
2326
2327                 $sql = "INSERT $insertOptions" .
2328                         " INTO $destTable (" . implode( ',', array_keys( $varMap ) ) . ')' .
2329                         " SELECT $startOpts " . implode( ',', $varMap ) .
2330                         " FROM $srcTable $useIndex $ignoreIndex ";
2331
2332                 if ( $conds != '*' ) {
2333                         if ( is_array( $conds ) ) {
2334                                 $conds = $this->makeList( $conds, self::LIST_AND );
2335                         }
2336                         $sql .= " WHERE $conds";
2337                 }
2338
2339                 $sql .= " $tailOpts";
2340
2341                 return $this->query( $sql, $fname );
2342         }
2343
2344         /**
2345          * Construct a LIMIT query with optional offset. This is used for query
2346          * pages. The SQL should be adjusted so that only the first $limit rows
2347          * are returned. If $offset is provided as well, then the first $offset
2348          * rows should be discarded, and the next $limit rows should be returned.
2349          * If the result of the query is not ordered, then the rows to be returned
2350          * are theoretically arbitrary.
2351          *
2352          * $sql is expected to be a SELECT, if that makes a difference.
2353          *
2354          * The version provided by default works in MySQL and SQLite. It will very
2355          * likely need to be overridden for most other DBMSes.
2356          *
2357          * @param string $sql SQL query we will append the limit too
2358          * @param int $limit The SQL limit
2359          * @param int|bool $offset The SQL offset (default false)
2360          * @throws DBUnexpectedError
2361          * @return string
2362          */
2363         public function limitResult( $sql, $limit, $offset = false ) {
2364                 if ( !is_numeric( $limit ) ) {
2365                         throw new DBUnexpectedError( $this,
2366                                 "Invalid non-numeric limit passed to limitResult()\n" );
2367                 }
2368
2369                 return "$sql LIMIT "
2370                 . ( ( is_numeric( $offset ) && $offset != 0 ) ? "{$offset}," : "" )
2371                 . "{$limit} ";
2372         }
2373
2374         public function unionSupportsOrderAndLimit() {
2375                 return true; // True for almost every DB supported
2376         }
2377
2378         public function unionQueries( $sqls, $all ) {
2379                 $glue = $all ? ') UNION ALL (' : ') UNION (';
2380
2381                 return '(' . implode( $glue, $sqls ) . ')';
2382         }
2383
2384         public function conditional( $cond, $trueVal, $falseVal ) {
2385                 if ( is_array( $cond ) ) {
2386                         $cond = $this->makeList( $cond, self::LIST_AND );
2387                 }
2388
2389                 return " (CASE WHEN $cond THEN $trueVal ELSE $falseVal END) ";
2390         }
2391
2392         public function strreplace( $orig, $old, $new ) {
2393                 return "REPLACE({$orig}, {$old}, {$new})";
2394         }
2395
2396         public function getServerUptime() {
2397                 return 0;
2398         }
2399
2400         public function wasDeadlock() {
2401                 return false;
2402         }
2403
2404         public function wasLockTimeout() {
2405                 return false;
2406         }
2407
2408         public function wasErrorReissuable() {
2409                 return false;
2410         }
2411
2412         public function wasReadOnlyError() {
2413                 return false;
2414         }
2415
2416         /**
2417          * Do not use this method outside of Database/DBError classes
2418          *
2419          * @param integer|string $errno
2420          * @return bool Whether the given query error was a connection drop
2421          */
2422         public function wasConnectionError( $errno ) {
2423                 return false;
2424         }
2425
2426         public function deadlockLoop() {
2427                 $args = func_get_args();
2428                 $function = array_shift( $args );
2429                 $tries = self::DEADLOCK_TRIES;
2430
2431                 $this->begin( __METHOD__ );
2432
2433                 $retVal = null;
2434                 /** @var Exception $e */
2435                 $e = null;
2436                 do {
2437                         try {
2438                                 $retVal = call_user_func_array( $function, $args );
2439                                 break;
2440                         } catch ( DBQueryError $e ) {
2441                                 if ( $this->wasDeadlock() ) {
2442                                         // Retry after a randomized delay
2443                                         usleep( mt_rand( self::DEADLOCK_DELAY_MIN, self::DEADLOCK_DELAY_MAX ) );
2444                                 } else {
2445                                         // Throw the error back up
2446                                         throw $e;
2447                                 }
2448                         }
2449                 } while ( --$tries > 0 );
2450
2451                 if ( $tries <= 0 ) {
2452                         // Too many deadlocks; give up
2453                         $this->rollback( __METHOD__ );
2454                         throw $e;
2455                 } else {
2456                         $this->commit( __METHOD__ );
2457
2458                         return $retVal;
2459                 }
2460         }
2461
2462         public function masterPosWait( DBMasterPos $pos, $timeout ) {
2463                 # Real waits are implemented in the subclass.
2464                 return 0;
2465         }
2466
2467         public function getReplicaPos() {
2468                 # Stub
2469                 return false;
2470         }
2471
2472         public function getMasterPos() {
2473                 # Stub
2474                 return false;
2475         }
2476
2477         public function serverIsReadOnly() {
2478                 return false;
2479         }
2480
2481         final public function onTransactionResolution( callable $callback, $fname = __METHOD__ ) {
2482                 if ( !$this->mTrxLevel ) {
2483                         throw new DBUnexpectedError( $this, "No transaction is active." );
2484                 }
2485                 $this->mTrxEndCallbacks[] = [ $callback, $fname ];
2486         }
2487
2488         final public function onTransactionIdle( callable $callback, $fname = __METHOD__ ) {
2489                 $this->mTrxIdleCallbacks[] = [ $callback, $fname ];
2490                 if ( !$this->mTrxLevel ) {
2491                         $this->runOnTransactionIdleCallbacks( self::TRIGGER_IDLE );
2492                 }
2493         }
2494
2495         final public function onTransactionPreCommitOrIdle( callable $callback, $fname = __METHOD__ ) {
2496                 if ( $this->mTrxLevel ) {
2497                         $this->mTrxPreCommitCallbacks[] = [ $callback, $fname ];
2498                 } else {
2499                         // If no transaction is active, then make one for this callback
2500                         $this->startAtomic( __METHOD__ );
2501                         try {
2502                                 call_user_func( $callback );
2503                                 $this->endAtomic( __METHOD__ );
2504                         } catch ( Exception $e ) {
2505                                 $this->rollback( __METHOD__, self::FLUSHING_INTERNAL );
2506                                 throw $e;
2507                         }
2508                 }
2509         }
2510
2511         final public function setTransactionListener( $name, callable $callback = null ) {
2512                 if ( $callback ) {
2513                         $this->mTrxRecurringCallbacks[$name] = $callback;
2514                 } else {
2515                         unset( $this->mTrxRecurringCallbacks[$name] );
2516                 }
2517         }
2518
2519         /**
2520          * Whether to disable running of post-COMMIT/ROLLBACK callbacks
2521          *
2522          * This method should not be used outside of Database/LoadBalancer
2523          *
2524          * @param bool $suppress
2525          * @since 1.28
2526          */
2527         final public function setTrxEndCallbackSuppression( $suppress ) {
2528                 $this->mTrxEndCallbacksSuppressed = $suppress;
2529         }
2530
2531         /**
2532          * Actually run and consume any "on transaction idle/resolution" callbacks.
2533          *
2534          * This method should not be used outside of Database/LoadBalancer
2535          *
2536          * @param integer $trigger IDatabase::TRIGGER_* constant
2537          * @since 1.20
2538          * @throws Exception
2539          */
2540         public function runOnTransactionIdleCallbacks( $trigger ) {
2541                 if ( $this->mTrxEndCallbacksSuppressed ) {
2542                         return;
2543                 }
2544
2545                 $autoTrx = $this->getFlag( self::DBO_TRX ); // automatic begin() enabled?
2546                 /** @var Exception $e */
2547                 $e = null; // first exception
2548                 do { // callbacks may add callbacks :)
2549                         $callbacks = array_merge(
2550                                 $this->mTrxIdleCallbacks,
2551                                 $this->mTrxEndCallbacks // include "transaction resolution" callbacks
2552                         );
2553                         $this->mTrxIdleCallbacks = []; // consumed (and recursion guard)
2554                         $this->mTrxEndCallbacks = []; // consumed (recursion guard)
2555                         foreach ( $callbacks as $callback ) {
2556                                 try {
2557                                         list( $phpCallback ) = $callback;
2558                                         $this->clearFlag( self::DBO_TRX ); // make each query its own transaction
2559                                         call_user_func_array( $phpCallback, [ $trigger ] );
2560                                         if ( $autoTrx ) {
2561                                                 $this->setFlag( self::DBO_TRX ); // restore automatic begin()
2562                                         } else {
2563                                                 $this->clearFlag( self::DBO_TRX ); // restore auto-commit
2564                                         }
2565                                 } catch ( Exception $ex ) {
2566                                         call_user_func( $this->errorLogger, $ex );
2567                                         $e = $e ?: $ex;
2568                                         // Some callbacks may use startAtomic/endAtomic, so make sure
2569                                         // their transactions are ended so other callbacks don't fail
2570                                         if ( $this->trxLevel() ) {
2571                                                 $this->rollback( __METHOD__, self::FLUSHING_INTERNAL );
2572                                         }
2573                                 }
2574                         }
2575                 } while ( count( $this->mTrxIdleCallbacks ) );
2576
2577                 if ( $e instanceof Exception ) {
2578                         throw $e; // re-throw any first exception
2579                 }
2580         }
2581
2582         /**
2583          * Actually run and consume any "on transaction pre-commit" callbacks.
2584          *
2585          * This method should not be used outside of Database/LoadBalancer
2586          *
2587          * @since 1.22
2588          * @throws Exception
2589          */
2590         public function runOnTransactionPreCommitCallbacks() {
2591                 $e = null; // first exception
2592                 do { // callbacks may add callbacks :)
2593                         $callbacks = $this->mTrxPreCommitCallbacks;
2594                         $this->mTrxPreCommitCallbacks = []; // consumed (and recursion guard)
2595                         foreach ( $callbacks as $callback ) {
2596                                 try {
2597                                         list( $phpCallback ) = $callback;
2598                                         call_user_func( $phpCallback );
2599                                 } catch ( Exception $ex ) {
2600                                         call_user_func( $this->errorLogger, $ex );
2601                                         $e = $e ?: $ex;
2602                                 }
2603                         }
2604                 } while ( count( $this->mTrxPreCommitCallbacks ) );
2605
2606                 if ( $e instanceof Exception ) {
2607                         throw $e; // re-throw any first exception
2608                 }
2609         }
2610
2611         /**
2612          * Actually run any "transaction listener" callbacks.
2613          *
2614          * This method should not be used outside of Database/LoadBalancer
2615          *
2616          * @param integer $trigger IDatabase::TRIGGER_* constant
2617          * @throws Exception
2618          * @since 1.20
2619          */
2620         public function runTransactionListenerCallbacks( $trigger ) {
2621                 if ( $this->mTrxEndCallbacksSuppressed ) {
2622                         return;
2623                 }
2624
2625                 /** @var Exception $e */
2626                 $e = null; // first exception
2627
2628                 foreach ( $this->mTrxRecurringCallbacks as $phpCallback ) {
2629                         try {
2630                                 $phpCallback( $trigger, $this );
2631                         } catch ( Exception $ex ) {
2632                                 call_user_func( $this->errorLogger, $ex );
2633                                 $e = $e ?: $ex;
2634                         }
2635                 }
2636
2637                 if ( $e instanceof Exception ) {
2638                         throw $e; // re-throw any first exception
2639                 }
2640         }
2641
2642         final public function startAtomic( $fname = __METHOD__ ) {
2643                 if ( !$this->mTrxLevel ) {
2644                         $this->begin( $fname, self::TRANSACTION_INTERNAL );
2645                         // If DBO_TRX is set, a series of startAtomic/endAtomic pairs will result
2646                         // in all changes being in one transaction to keep requests transactional.
2647                         if ( !$this->getFlag( self::DBO_TRX ) ) {
2648                                 $this->mTrxAutomaticAtomic = true;
2649                         }
2650                 }
2651
2652                 $this->mTrxAtomicLevels[] = $fname;
2653         }
2654
2655         final public function endAtomic( $fname = __METHOD__ ) {
2656                 if ( !$this->mTrxLevel ) {
2657                         throw new DBUnexpectedError( $this, "No atomic transaction is open (got $fname)." );
2658                 }
2659                 if ( !$this->mTrxAtomicLevels ||
2660                         array_pop( $this->mTrxAtomicLevels ) !== $fname
2661                 ) {
2662                         throw new DBUnexpectedError( $this, "Invalid atomic section ended (got $fname)." );
2663                 }
2664
2665                 if ( !$this->mTrxAtomicLevels && $this->mTrxAutomaticAtomic ) {
2666                         $this->commit( $fname, self::FLUSHING_INTERNAL );
2667                 }
2668         }
2669
2670         final public function doAtomicSection( $fname, callable $callback ) {
2671                 $this->startAtomic( $fname );
2672                 try {
2673                         $res = call_user_func_array( $callback, [ $this, $fname ] );
2674                 } catch ( Exception $e ) {
2675                         $this->rollback( $fname, self::FLUSHING_INTERNAL );
2676                         throw $e;
2677                 }
2678                 $this->endAtomic( $fname );
2679
2680                 return $res;
2681         }
2682
2683         final public function begin( $fname = __METHOD__, $mode = self::TRANSACTION_EXPLICIT ) {
2684                 // Protect against mismatched atomic section, transaction nesting, and snapshot loss
2685                 if ( $this->mTrxLevel ) {
2686                         if ( $this->mTrxAtomicLevels ) {
2687                                 $levels = implode( ', ', $this->mTrxAtomicLevels );
2688                                 $msg = "$fname: Got explicit BEGIN while atomic section(s) $levels are open.";
2689                                 throw new DBUnexpectedError( $this, $msg );
2690                         } elseif ( !$this->mTrxAutomatic ) {
2691                                 $msg = "$fname: Explicit transaction already active (from {$this->mTrxFname}).";
2692                                 throw new DBUnexpectedError( $this, $msg );
2693                         } else {
2694                                 // @TODO: make this an exception at some point
2695                                 $msg = "$fname: Implicit transaction already active (from {$this->mTrxFname}).";
2696                                 $this->queryLogger->error( $msg );
2697                                 return; // join the main transaction set
2698                         }
2699                 } elseif ( $this->getFlag( self::DBO_TRX ) && $mode !== self::TRANSACTION_INTERNAL ) {
2700                         // @TODO: make this an exception at some point
2701                         $msg = "$fname: Implicit transaction expected (DBO_TRX set).";
2702                         $this->queryLogger->error( $msg );
2703                         return; // let any writes be in the main transaction
2704                 }
2705
2706                 // Avoid fatals if close() was called
2707                 $this->assertOpen();
2708
2709                 $this->doBegin( $fname );
2710                 $this->mTrxTimestamp = microtime( true );
2711                 $this->mTrxFname = $fname;
2712                 $this->mTrxDoneWrites = false;
2713                 $this->mTrxAutomaticAtomic = false;
2714                 $this->mTrxAtomicLevels = [];
2715                 $this->mTrxShortId = sprintf( '%06x', mt_rand( 0, 0xffffff ) );
2716                 $this->mTrxWriteDuration = 0.0;
2717                 $this->mTrxWriteQueryCount = 0;
2718                 $this->mTrxWriteAdjDuration = 0.0;
2719                 $this->mTrxWriteAdjQueryCount = 0;
2720                 $this->mTrxWriteCallers = [];
2721                 // First SELECT after BEGIN will establish the snapshot in REPEATABLE-READ.
2722                 // Get an estimate of the replica DB lag before then, treating estimate staleness
2723                 // as lag itself just to be safe
2724                 $status = $this->getApproximateLagStatus();
2725                 $this->mTrxReplicaLag = $status['lag'] + ( microtime( true ) - $status['since'] );
2726                 // T147697: make explicitTrxActive() return true until begin() finishes. This way, no
2727                 // caller will think its OK to muck around with the transaction just because startAtomic()
2728                 // has not yet completed (e.g. setting mTrxAtomicLevels).
2729                 $this->mTrxAutomatic = ( $mode === self::TRANSACTION_INTERNAL );
2730         }
2731
2732         /**
2733          * Issues the BEGIN command to the database server.
2734          *
2735          * @see Database::begin()
2736          * @param string $fname
2737          */
2738         protected function doBegin( $fname ) {
2739                 $this->query( 'BEGIN', $fname );
2740                 $this->mTrxLevel = 1;
2741         }
2742
2743         final public function commit( $fname = __METHOD__, $flush = '' ) {
2744                 if ( $this->mTrxLevel && $this->mTrxAtomicLevels ) {
2745                         // There are still atomic sections open. This cannot be ignored
2746                         $levels = implode( ', ', $this->mTrxAtomicLevels );
2747                         throw new DBUnexpectedError(
2748                                 $this,
2749                                 "$fname: Got COMMIT while atomic sections $levels are still open."
2750                         );
2751                 }
2752
2753                 if ( $flush === self::FLUSHING_INTERNAL || $flush === self::FLUSHING_ALL_PEERS ) {
2754                         if ( !$this->mTrxLevel ) {
2755                                 return; // nothing to do
2756                         } elseif ( !$this->mTrxAutomatic ) {
2757                                 throw new DBUnexpectedError(
2758                                         $this,
2759                                         "$fname: Flushing an explicit transaction, getting out of sync."
2760                                 );
2761                         }
2762                 } else {
2763                         if ( !$this->mTrxLevel ) {
2764                                 $this->queryLogger->error(
2765                                         "$fname: No transaction to commit, something got out of sync." );
2766                                 return; // nothing to do
2767                         } elseif ( $this->mTrxAutomatic ) {
2768                                 // @TODO: make this an exception at some point
2769                                 $msg = "$fname: Explicit commit of implicit transaction.";
2770                                 $this->queryLogger->error( $msg );
2771                                 return; // wait for the main transaction set commit round
2772                         }
2773                 }
2774
2775                 // Avoid fatals if close() was called
2776                 $this->assertOpen();
2777
2778                 $this->runOnTransactionPreCommitCallbacks();
2779                 $writeTime = $this->pendingWriteQueryDuration( self::ESTIMATE_DB_APPLY );
2780                 $this->doCommit( $fname );
2781                 if ( $this->mTrxDoneWrites ) {
2782                         $this->mLastWriteTime = microtime( true );
2783                         $this->trxProfiler->transactionWritingOut(
2784                                 $this->mServer, $this->mDBname, $this->mTrxShortId, $writeTime );
2785                 }
2786
2787                 $this->runOnTransactionIdleCallbacks( self::TRIGGER_COMMIT );
2788                 $this->runTransactionListenerCallbacks( self::TRIGGER_COMMIT );
2789         }
2790
2791         /**
2792          * Issues the COMMIT command to the database server.
2793          *
2794          * @see Database::commit()
2795          * @param string $fname
2796          */
2797         protected function doCommit( $fname ) {
2798                 if ( $this->mTrxLevel ) {
2799                         $this->query( 'COMMIT', $fname );
2800                         $this->mTrxLevel = 0;
2801                 }
2802         }
2803
2804         final public function rollback( $fname = __METHOD__, $flush = '' ) {
2805                 if ( $flush === self::FLUSHING_INTERNAL || $flush === self::FLUSHING_ALL_PEERS ) {
2806                         if ( !$this->mTrxLevel ) {
2807                                 return; // nothing to do
2808                         }
2809                 } else {
2810                         if ( !$this->mTrxLevel ) {
2811                                 $this->queryLogger->error(
2812                                         "$fname: No transaction to rollback, something got out of sync." );
2813                                 return; // nothing to do
2814                         } elseif ( $this->getFlag( self::DBO_TRX ) ) {
2815                                 throw new DBUnexpectedError(
2816                                         $this,
2817                                         "$fname: Expected mass rollback of all peer databases (DBO_TRX set)."
2818                                 );
2819                         }
2820                 }
2821
2822                 // Avoid fatals if close() was called
2823                 $this->assertOpen();
2824
2825                 $this->doRollback( $fname );
2826                 $this->mTrxAtomicLevels = [];
2827                 if ( $this->mTrxDoneWrites ) {
2828                         $this->trxProfiler->transactionWritingOut(
2829                                 $this->mServer, $this->mDBname, $this->mTrxShortId );
2830                 }
2831
2832                 $this->mTrxIdleCallbacks = []; // clear
2833                 $this->mTrxPreCommitCallbacks = []; // clear
2834                 $this->runOnTransactionIdleCallbacks( self::TRIGGER_ROLLBACK );
2835                 $this->runTransactionListenerCallbacks( self::TRIGGER_ROLLBACK );
2836         }
2837
2838         /**
2839          * Issues the ROLLBACK command to the database server.
2840          *
2841          * @see Database::rollback()
2842          * @param string $fname
2843          */
2844         protected function doRollback( $fname ) {
2845                 if ( $this->mTrxLevel ) {
2846                         # Disconnects cause rollback anyway, so ignore those errors
2847                         $ignoreErrors = true;
2848                         $this->query( 'ROLLBACK', $fname, $ignoreErrors );
2849                         $this->mTrxLevel = 0;
2850                 }
2851         }
2852
2853         public function flushSnapshot( $fname = __METHOD__ ) {
2854                 if ( $this->writesOrCallbacksPending() || $this->explicitTrxActive() ) {
2855                         // This only flushes transactions to clear snapshots, not to write data
2856                         $fnames = implode( ', ', $this->pendingWriteAndCallbackCallers() );
2857                         throw new DBUnexpectedError(
2858                                 $this,
2859                                 "$fname: Cannot flush snapshot because writes are pending ($fnames)."
2860                         );
2861                 }
2862
2863                 $this->commit( $fname, self::FLUSHING_INTERNAL );
2864         }
2865
2866         public function explicitTrxActive() {
2867                 return $this->mTrxLevel && ( $this->mTrxAtomicLevels || !$this->mTrxAutomatic );
2868         }
2869
2870         public function duplicateTableStructure(
2871                 $oldName, $newName, $temporary = false, $fname = __METHOD__
2872         ) {
2873                 throw new RuntimeException( __METHOD__ . ' is not implemented in descendant class' );
2874         }
2875
2876         public function listTables( $prefix = null, $fname = __METHOD__ ) {
2877                 throw new RuntimeException( __METHOD__ . ' is not implemented in descendant class' );
2878         }
2879
2880         public function listViews( $prefix = null, $fname = __METHOD__ ) {
2881                 throw new RuntimeException( __METHOD__ . ' is not implemented in descendant class' );
2882         }
2883
2884         public function timestamp( $ts = 0 ) {
2885                 $t = new ConvertibleTimestamp( $ts );
2886                 // Let errors bubble up to avoid putting garbage in the DB
2887                 return $t->getTimestamp( TS_MW );
2888         }
2889
2890         public function timestampOrNull( $ts = null ) {
2891                 if ( is_null( $ts ) ) {
2892                         return null;
2893                 } else {
2894                         return $this->timestamp( $ts );
2895                 }
2896         }
2897
2898         /**
2899          * Take the result from a query, and wrap it in a ResultWrapper if
2900          * necessary. Boolean values are passed through as is, to indicate success
2901          * of write queries or failure.
2902          *
2903          * Once upon a time, Database::query() returned a bare MySQL result
2904          * resource, and it was necessary to call this function to convert it to
2905          * a wrapper. Nowadays, raw database objects are never exposed to external
2906          * callers, so this is unnecessary in external code.
2907          *
2908          * @param bool|ResultWrapper|resource|object $result
2909          * @return bool|ResultWrapper
2910          */
2911         protected function resultObject( $result ) {
2912                 if ( !$result ) {
2913                         return false;
2914                 } elseif ( $result instanceof ResultWrapper ) {
2915                         return $result;
2916                 } elseif ( $result === true ) {
2917                         // Successful write query
2918                         return $result;
2919                 } else {
2920                         return new ResultWrapper( $this, $result );
2921                 }
2922         }
2923
2924         public function ping( &$rtt = null ) {
2925                 // Avoid hitting the server if it was hit recently
2926                 if ( $this->isOpen() && ( microtime( true ) - $this->lastPing ) < self::PING_TTL ) {
2927                         if ( !func_num_args() || $this->mRTTEstimate > 0 ) {
2928                                 $rtt = $this->mRTTEstimate;
2929                                 return true; // don't care about $rtt
2930                         }
2931                 }
2932
2933                 // This will reconnect if possible or return false if not
2934                 $this->clearFlag( self::DBO_TRX, self::REMEMBER_PRIOR );
2935                 $ok = ( $this->query( self::PING_QUERY, __METHOD__, true ) !== false );
2936                 $this->restoreFlags( self::RESTORE_PRIOR );
2937
2938                 if ( $ok ) {
2939                         $rtt = $this->mRTTEstimate;
2940                 }
2941
2942                 return $ok;
2943         }
2944
2945         /**
2946          * @return bool
2947          */
2948         protected function reconnect() {
2949                 $this->closeConnection();
2950                 $this->mOpened = false;
2951                 $this->mConn = false;
2952                 try {
2953                         $this->open( $this->mServer, $this->mUser, $this->mPassword, $this->mDBname );
2954                         $this->lastPing = microtime( true );
2955                         $ok = true;
2956                 } catch ( DBConnectionError $e ) {
2957                         $ok = false;
2958                 }
2959
2960                 return $ok;
2961         }
2962
2963         public function getSessionLagStatus() {
2964                 return $this->getTransactionLagStatus() ?: $this->getApproximateLagStatus();
2965         }
2966
2967         /**
2968          * Get the replica DB lag when the current transaction started
2969          *
2970          * This is useful when transactions might use snapshot isolation
2971          * (e.g. REPEATABLE-READ in innodb), so the "real" lag of that data
2972          * is this lag plus transaction duration. If they don't, it is still
2973          * safe to be pessimistic. This returns null if there is no transaction.
2974          *
2975          * @return array|null ('lag': seconds or false on error, 'since': UNIX timestamp of BEGIN)
2976          * @since 1.27
2977          */
2978         protected function getTransactionLagStatus() {
2979                 return $this->mTrxLevel
2980                         ? [ 'lag' => $this->mTrxReplicaLag, 'since' => $this->trxTimestamp() ]
2981                         : null;
2982         }
2983
2984         /**
2985          * Get a replica DB lag estimate for this server
2986          *
2987          * @return array ('lag': seconds or false on error, 'since': UNIX timestamp of estimate)
2988          * @since 1.27
2989          */
2990         protected function getApproximateLagStatus() {
2991                 return [
2992                         'lag'   => $this->getLBInfo( 'replica' ) ? $this->getLag() : 0,
2993                         'since' => microtime( true )
2994                 ];
2995         }
2996
2997         /**
2998          * Merge the result of getSessionLagStatus() for several DBs
2999          * using the most pessimistic values to estimate the lag of
3000          * any data derived from them in combination
3001          *
3002          * This is information is useful for caching modules
3003          *
3004          * @see WANObjectCache::set()
3005          * @see WANObjectCache::getWithSetCallback()
3006          *
3007          * @param IDatabase $db1
3008          * @param IDatabase ...
3009          * @return array Map of values:
3010          *   - lag: highest lag of any of the DBs or false on error (e.g. replication stopped)
3011          *   - since: oldest UNIX timestamp of any of the DB lag estimates
3012          *   - pending: whether any of the DBs have uncommitted changes
3013          * @since 1.27
3014          */
3015         public static function getCacheSetOptions( IDatabase $db1 ) {
3016                 $res = [ 'lag' => 0, 'since' => INF, 'pending' => false ];
3017                 foreach ( func_get_args() as $db ) {
3018                         /** @var IDatabase $db */
3019                         $status = $db->getSessionLagStatus();
3020                         if ( $status['lag'] === false ) {
3021                                 $res['lag'] = false;
3022                         } elseif ( $res['lag'] !== false ) {
3023                                 $res['lag'] = max( $res['lag'], $status['lag'] );
3024                         }
3025                         $res['since'] = min( $res['since'], $status['since'] );
3026                         $res['pending'] = $res['pending'] ?: $db->writesPending();
3027                 }
3028
3029                 return $res;
3030         }
3031
3032         public function getLag() {
3033                 return 0;
3034         }
3035
3036         public function maxListLen() {
3037                 return 0;
3038         }
3039
3040         public function encodeBlob( $b ) {
3041                 return $b;
3042         }
3043
3044         public function decodeBlob( $b ) {
3045                 if ( $b instanceof Blob ) {
3046                         $b = $b->fetch();
3047                 }
3048                 return $b;
3049         }
3050
3051         public function setSessionOptions( array $options ) {
3052         }
3053
3054         public function sourceFile(
3055                 $filename,
3056                 callable $lineCallback = null,
3057                 callable $resultCallback = null,
3058                 $fname = false,
3059                 callable $inputCallback = null
3060         ) {
3061                 MediaWiki\suppressWarnings();
3062                 $fp = fopen( $filename, 'r' );
3063                 MediaWiki\restoreWarnings();
3064
3065                 if ( false === $fp ) {
3066                         throw new RuntimeException( "Could not open \"{$filename}\".\n" );
3067                 }
3068
3069                 if ( !$fname ) {
3070                         $fname = __METHOD__ . "( $filename )";
3071                 }
3072
3073                 try {
3074                         $error = $this->sourceStream(
3075                                 $fp, $lineCallback, $resultCallback, $fname, $inputCallback );
3076                 } catch ( Exception $e ) {
3077                         fclose( $fp );
3078                         throw $e;
3079                 }
3080
3081                 fclose( $fp );
3082
3083                 return $error;
3084         }
3085
3086         public function setSchemaVars( $vars ) {
3087                 $this->mSchemaVars = $vars;
3088         }
3089
3090         public function sourceStream(
3091                 $fp,
3092                 callable $lineCallback = null,
3093                 callable $resultCallback = null,
3094                 $fname = __METHOD__,
3095                 callable $inputCallback = null
3096         ) {
3097                 $cmd = '';
3098
3099                 while ( !feof( $fp ) ) {
3100                         if ( $lineCallback ) {
3101                                 call_user_func( $lineCallback );
3102                         }
3103
3104                         $line = trim( fgets( $fp ) );
3105
3106                         if ( $line == '' ) {
3107                                 continue;
3108                         }
3109
3110                         if ( '-' == $line[0] && '-' == $line[1] ) {
3111                                 continue;
3112                         }
3113
3114                         if ( $cmd != '' ) {
3115                                 $cmd .= ' ';
3116                         }
3117
3118                         $done = $this->streamStatementEnd( $cmd, $line );
3119
3120                         $cmd .= "$line\n";
3121
3122                         if ( $done || feof( $fp ) ) {
3123                                 $cmd = $this->replaceVars( $cmd );
3124
3125                                 if ( !$inputCallback || call_user_func( $inputCallback, $cmd ) ) {
3126                                         $res = $this->query( $cmd, $fname );
3127
3128                                         if ( $resultCallback ) {
3129                                                 call_user_func( $resultCallback, $res, $this );
3130                                         }
3131
3132                                         if ( false === $res ) {
3133                                                 $err = $this->lastError();
3134
3135                                                 return "Query \"{$cmd}\" failed with error code \"$err\".\n";
3136                                         }
3137                                 }
3138                                 $cmd = '';
3139                         }
3140                 }
3141
3142                 return true;
3143         }
3144
3145         /**
3146          * Called by sourceStream() to check if we've reached a statement end
3147          *
3148          * @param string &$sql SQL assembled so far
3149          * @param string &$newLine New line about to be added to $sql
3150          * @return bool Whether $newLine contains end of the statement
3151          */
3152         public function streamStatementEnd( &$sql, &$newLine ) {
3153                 if ( $this->delimiter ) {
3154                         $prev = $newLine;
3155                         $newLine = preg_replace(
3156                                 '/' . preg_quote( $this->delimiter, '/' ) . '$/', '', $newLine );
3157                         if ( $newLine != $prev ) {
3158                                 return true;
3159                         }
3160                 }
3161
3162                 return false;
3163         }
3164
3165         /**
3166          * Database independent variable replacement. Replaces a set of variables
3167          * in an SQL statement with their contents as given by $this->getSchemaVars().
3168          *
3169          * Supports '{$var}' `{$var}` and / *$var* / (without the spaces) style variables.
3170          *
3171          * - '{$var}' should be used for text and is passed through the database's
3172          *   addQuotes method.
3173          * - `{$var}` should be used for identifiers (e.g. table and database names).
3174          *   It is passed through the database's addIdentifierQuotes method which
3175          *   can be overridden if the database uses something other than backticks.
3176          * - / *_* / or / *$wgDBprefix* / passes the name that follows through the
3177          *   database's tableName method.
3178          * - / *i* / passes the name that follows through the database's indexName method.
3179          * - In all other cases, / *$var* / is left unencoded. Except for table options,
3180          *   its use should be avoided. In 1.24 and older, string encoding was applied.
3181          *
3182          * @param string $ins SQL statement to replace variables in
3183          * @return string The new SQL statement with variables replaced
3184          */
3185         protected function replaceVars( $ins ) {
3186                 $vars = $this->getSchemaVars();
3187                 return preg_replace_callback(
3188                         '!
3189                                 /\* (\$wgDBprefix|[_i]) \*/ (\w*) | # 1-2. tableName, indexName
3190                                 \'\{\$ (\w+) }\'                  | # 3. addQuotes
3191                                 `\{\$ (\w+) }`                    | # 4. addIdentifierQuotes
3192                                 /\*\$ (\w+) \*/                     # 5. leave unencoded
3193                         !x',
3194                         function ( $m ) use ( $vars ) {
3195                                 // Note: Because of <https://bugs.php.net/bug.php?id=51881>,
3196                                 // check for both nonexistent keys *and* the empty string.
3197                                 if ( isset( $m[1] ) && $m[1] !== '' ) {
3198                                         if ( $m[1] === 'i' ) {
3199                                                 return $this->indexName( $m[2] );
3200                                         } else {
3201                                                 return $this->tableName( $m[2] );
3202                                         }
3203                                 } elseif ( isset( $m[3] ) && $m[3] !== '' && array_key_exists( $m[3], $vars ) ) {
3204                                         return $this->addQuotes( $vars[$m[3]] );
3205                                 } elseif ( isset( $m[4] ) && $m[4] !== '' && array_key_exists( $m[4], $vars ) ) {
3206                                         return $this->addIdentifierQuotes( $vars[$m[4]] );
3207                                 } elseif ( isset( $m[5] ) && $m[5] !== '' && array_key_exists( $m[5], $vars ) ) {
3208                                         return $vars[$m[5]];
3209                                 } else {
3210                                         return $m[0];
3211                                 }
3212                         },
3213                         $ins
3214                 );
3215         }
3216
3217         /**
3218          * Get schema variables. If none have been set via setSchemaVars(), then
3219          * use some defaults from the current object.
3220          *
3221          * @return array
3222          */
3223         protected function getSchemaVars() {
3224                 if ( $this->mSchemaVars ) {
3225                         return $this->mSchemaVars;
3226                 } else {
3227                         return $this->getDefaultSchemaVars();
3228                 }
3229         }
3230
3231         /**
3232          * Get schema variables to use if none have been set via setSchemaVars().
3233          *
3234          * Override this in derived classes to provide variables for tables.sql
3235          * and SQL patch files.
3236          *
3237          * @return array
3238          */
3239         protected function getDefaultSchemaVars() {
3240                 return [];
3241         }
3242
3243         public function lockIsFree( $lockName, $method ) {
3244                 return true;
3245         }
3246
3247         public function lock( $lockName, $method, $timeout = 5 ) {
3248                 $this->mNamedLocksHeld[$lockName] = 1;
3249
3250                 return true;
3251         }
3252
3253         public function unlock( $lockName, $method ) {
3254                 unset( $this->mNamedLocksHeld[$lockName] );
3255
3256                 return true;
3257         }
3258
3259         public function getScopedLockAndFlush( $lockKey, $fname, $timeout ) {
3260                 if ( $this->writesOrCallbacksPending() ) {
3261                         // This only flushes transactions to clear snapshots, not to write data
3262                         $fnames = implode( ', ', $this->pendingWriteAndCallbackCallers() );
3263                         throw new DBUnexpectedError(
3264                                 $this,
3265                                 "$fname: Cannot flush pre-lock snapshot because writes are pending ($fnames)."
3266                         );
3267                 }
3268
3269                 if ( !$this->lock( $lockKey, $fname, $timeout ) ) {
3270                         return null;
3271                 }
3272
3273                 $unlocker = new ScopedCallback( function () use ( $lockKey, $fname ) {
3274                         if ( $this->trxLevel() ) {
3275                                 // There is a good chance an exception was thrown, causing any early return
3276                                 // from the caller. Let any error handler get a chance to issue rollback().
3277                                 // If there isn't one, let the error bubble up and trigger server-side rollback.
3278                                 $this->onTransactionResolution(
3279                                         function () use ( $lockKey, $fname ) {
3280                                                 $this->unlock( $lockKey, $fname );
3281                                         },
3282                                         $fname
3283                                 );
3284                         } else {
3285                                 $this->unlock( $lockKey, $fname );
3286                         }
3287                 } );
3288
3289                 $this->commit( $fname, self::FLUSHING_INTERNAL );
3290
3291                 return $unlocker;
3292         }
3293
3294         public function namedLocksEnqueue() {
3295                 return false;
3296         }
3297
3298         /**
3299          * Lock specific tables
3300          *
3301          * @param array $read Array of tables to lock for read access
3302          * @param array $write Array of tables to lock for write access
3303          * @param string $method Name of caller
3304          * @param bool $lowPriority Whether to indicate writes to be LOW PRIORITY
3305          * @return bool
3306          */
3307         public function lockTables( $read, $write, $method, $lowPriority = true ) {
3308                 return true;
3309         }
3310
3311         /**
3312          * Unlock specific tables
3313          *
3314          * @param string $method The caller
3315          * @return bool
3316          */
3317         public function unlockTables( $method ) {
3318                 return true;
3319         }
3320
3321         /**
3322          * Delete a table
3323          * @param string $tableName
3324          * @param string $fName
3325          * @return bool|ResultWrapper
3326          * @since 1.18
3327          */
3328         public function dropTable( $tableName, $fName = __METHOD__ ) {
3329                 if ( !$this->tableExists( $tableName, $fName ) ) {
3330                         return false;
3331                 }
3332                 $sql = "DROP TABLE " . $this->tableName( $tableName ) . " CASCADE";
3333
3334                 return $this->query( $sql, $fName );
3335         }
3336
3337         public function getInfinity() {
3338                 return 'infinity';
3339         }
3340
3341         public function encodeExpiry( $expiry ) {
3342                 return ( $expiry == '' || $expiry == 'infinity' || $expiry == $this->getInfinity() )
3343                         ? $this->getInfinity()
3344                         : $this->timestamp( $expiry );
3345         }
3346
3347         public function decodeExpiry( $expiry, $format = TS_MW ) {
3348                 if ( $expiry == '' || $expiry == 'infinity' || $expiry == $this->getInfinity() ) {
3349                         return 'infinity';
3350                 }
3351
3352                 return ConvertibleTimestamp::convert( $format, $expiry );
3353         }
3354
3355         public function setBigSelects( $value = true ) {
3356                 // no-op
3357         }
3358
3359         public function isReadOnly() {
3360                 return ( $this->getReadOnlyReason() !== false );
3361         }
3362
3363         /**
3364          * @return string|bool Reason this DB is read-only or false if it is not
3365          */
3366         protected function getReadOnlyReason() {
3367                 $reason = $this->getLBInfo( 'readOnlyReason' );
3368
3369                 return is_string( $reason ) ? $reason : false;
3370         }
3371
3372         public function setTableAliases( array $aliases ) {
3373                 $this->tableAliases = $aliases;
3374         }
3375
3376         /**
3377          * @return bool Whether a DB user is required to access the DB
3378          * @since 1.28
3379          */
3380         protected function requiresDatabaseUser() {
3381                 return true;
3382         }
3383
3384         /**
3385          * Get the underlying binding handle, mConn
3386          *
3387          * Makes sure that mConn is set (disconnects and ping() failure can unset it).
3388          * This catches broken callers than catch and ignore disconnection exceptions.
3389          * Unlike checking isOpen(), this is safe to call inside of open().
3390          *
3391          * @return resource|object
3392          * @throws DBUnexpectedError
3393          * @since 1.26
3394          */
3395         protected function getBindingHandle() {
3396                 if ( !$this->mConn ) {
3397                         throw new DBUnexpectedError(
3398                                 $this,
3399                                 'DB connection was already closed or the connection dropped.'
3400                         );
3401                 }
3402
3403                 return $this->mConn;
3404         }
3405
3406         /**
3407          * @since 1.19
3408          * @return string
3409          */
3410         public function __toString() {
3411                 return (string)$this->mConn;
3412         }
3413
3414         /**
3415          * Make sure that copies do not share the same client binding handle
3416          * @throws DBConnectionError
3417          */
3418         public function __clone() {
3419                 $this->connLogger->warning(
3420                         "Cloning " . static::class . " is not recomended; forking connection:\n" .
3421                         ( new RuntimeException() )->getTraceAsString()
3422                 );
3423
3424                 if ( $this->isOpen() ) {
3425                         // Open a new connection resource without messing with the old one
3426                         $this->mOpened = false;
3427                         $this->mConn = false;
3428                         $this->mTrxEndCallbacks = []; // don't copy
3429                         $this->handleSessionLoss(); // no trx or locks anymore
3430                         $this->open( $this->mServer, $this->mUser, $this->mPassword, $this->mDBname );
3431                         $this->lastPing = microtime( true );
3432                 }
3433         }
3434
3435         /**
3436          * Called by serialize. Throw an exception when DB connection is serialized.
3437          * This causes problems on some database engines because the connection is
3438          * not restored on unserialize.
3439          */
3440         public function __sleep() {
3441                 throw new RuntimeException( 'Database serialization may cause problems, since ' .
3442                         'the connection is not restored on wakeup.' );
3443         }
3444
3445         /**
3446          * Run a few simple sanity checks and close dangling connections
3447          */
3448         public function __destruct() {
3449                 if ( $this->mTrxLevel && $this->mTrxDoneWrites ) {
3450                         trigger_error( "Uncommitted DB writes (transaction from {$this->mTrxFname})." );
3451                 }
3452
3453                 $danglingWriters = $this->pendingWriteAndCallbackCallers();
3454                 if ( $danglingWriters ) {
3455                         $fnames = implode( ', ', $danglingWriters );
3456                         trigger_error( "DB transaction writes or callbacks still pending ($fnames)." );
3457                 }
3458
3459                 if ( $this->mConn ) {
3460                         // Avoid connection leaks for sanity. Normally, resources close at script completion.
3461                         // The connection might already be closed in zend/hhvm by now, so suppress warnings.
3462                         \MediaWiki\suppressWarnings();
3463                         $this->closeConnection();
3464                         \MediaWiki\restoreWarnings();
3465                         $this->mConn = false;
3466                         $this->mOpened = false;
3467                 }
3468         }
3469 }
3470
3471 class_alias( Database::class, 'DatabaseBase' );