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\DBMasterPos;
  33 use Wikimedia\Rdbms\Blob;
  34
  35 /**
  36  * Relational database abstraction object
  37  *
  38  * @ingroup Database
  39  * @since 1.28
  40  */
  41 abstract class Database implements IDatabase, IMaintainableDatabase, LoggerAwareInterface {
  42         /** Number of times to re-try an operation in case of deadlock */
  43         const DEADLOCK_TRIES = 4;
  44         /** Minimum time to wait before retry, in microseconds */
  45         const DEADLOCK_DELAY_MIN = 500000;
  46         /** Maximum time to wait before retry */
  47         const DEADLOCK_DELAY_MAX = 1500000;
  48
  49         /** How long before it is worth doing a dummy query to test the connection */
  50         const PING_TTL = 1.0;
  51         const PING_QUERY = 'SELECT 1 AS ping';
  52
  53         const TINY_WRITE_SEC = .010;
  54         const SLOW_WRITE_SEC = .500;
  55         const SMALL_WRITE_ROWS = 100;
  56
  57         /** @var string SQL query */
  58         protected $mLastQuery = '';
  59         /** @var float|bool UNIX timestamp of last write query */
  60         protected $mLastWriteTime = false;
  61         /** @var string|bool */
  62         protected $mPHPError = false;
  63         /** @var string */
  64         protected $mServer;
  65         /** @var string */
  66         protected $mUser;
  67         /** @var string */
  68         protected $mPassword;
  69         /** @var string */
  70         protected $mDBname;
  71         /** @var array[] $aliases Map of (table => (dbname, schema, prefix) map) */
  72         protected $tableAliases = [];
  73         /** @var bool Whether this PHP instance is for a CLI script */
  74         protected $cliMode;
  75         /** @var string Agent name for query profiling */
  76         protected $agent;
  77
  78         /** @var BagOStuff APC cache */
  79         protected $srvCache;
  80         /** @var LoggerInterface */
  81         protected $connLogger;
  82         /** @var LoggerInterface */
  83         protected $queryLogger;
  84         /** @var callback Error logging callback */
  85         protected $errorLogger;
  86
  87         /** @var resource|null Database connection */
  88         protected $mConn = null;
  89         /** @var bool */
  90         protected $mOpened = false;
  91
  92         /** @var array[] List of (callable, method name) */
  93         protected $mTrxIdleCallbacks = [];
  94         /** @var array[] List of (callable, method name) */
  95         protected $mTrxPreCommitCallbacks = [];
  96         /** @var array[] List of (callable, method name) */
  97         protected $mTrxEndCallbacks = [];
  98         /** @var callable[] Map of (name => callable) */
  99         protected $mTrxRecurringCallbacks = [];
 100         /** @var bool Whether to suppress triggering of transaction end callbacks */
 101         protected $mTrxEndCallbacksSuppressed = false;
 102
 103         /** @var string */
 104         protected $mTablePrefix = '';
 105         /** @var string */
 106         protected $mSchema = '';
 107         /** @var integer */
 108         protected $mFlags;
 109         /** @var array */
 110         protected $mLBInfo = [];
 111         /** @var bool|null */
 112         protected $mDefaultBigSelects = null;
 113         /** @var array|bool */
 114         protected $mSchemaVars = false;
 115         /** @var array */
 116         protected $mSessionVars = [];
 117         /** @var array|null */
 118         protected $preparedArgs;
 119         /** @var string|bool|null Stashed value of html_errors INI setting */
 120         protected $htmlErrors;
 121         /** @var string */
 122         protected $delimiter = ';';
 123         /** @var DatabaseDomain */
 124         protected $currentDomain;
 125
 126         /**
 127          * Either 1 if a transaction is active or 0 otherwise.
 128          * The other Trx fields may not be meaningfull if this is 0.
 129          *
 130          * @var int
 131          */
 132         protected $mTrxLevel = 0;
 133         /**
 134          * Either a short hexidecimal string if a transaction is active or ""
 135          *
 136          * @var string
 137          * @see Database::mTrxLevel
 138          */
 139         protected $mTrxShortId = '';
 140         /**
 141          * The UNIX time that the transaction started. Callers can assume that if
 142          * snapshot isolation is used, then the data is *at least* up to date to that
 143          * point (possibly more up-to-date since the first SELECT defines the snapshot).
 144          *
 145          * @var float|null
 146          * @see Database::mTrxLevel
 147          */
 148         private $mTrxTimestamp = null;
 149         /** @var float Lag estimate at the time of BEGIN */
 150         private $mTrxReplicaLag = null;
 151         /**
 152          * Remembers the function name given for starting the most recent transaction via begin().
 153          * Used to provide additional context for error reporting.
 154          *
 155          * @var string
 156          * @see Database::mTrxLevel
 157          */
 158         private $mTrxFname = null;
 159         /**
 160          * Record if possible write queries were done in the last transaction started
 161          *
 162          * @var bool
 163          * @see Database::mTrxLevel
 164          */
 165         private $mTrxDoneWrites = false;
 166         /**
 167          * Record if the current transaction was started implicitly due to DBO_TRX being set.
 168          *
 169          * @var bool
 170          * @see Database::mTrxLevel
 171          */
 172         private $mTrxAutomatic = false;
 173         /**
 174          * Array of levels of atomicity within transactions
 175          *
 176          * @var array
 177          */
 178         private $mTrxAtomicLevels = [];
 179         /**
 180          * Record if the current transaction was started implicitly by Database::startAtomic
 181          *
 182          * @var bool
 183          */
 184         private $mTrxAutomaticAtomic = false;
 185         /**
 186          * Track the write query callers of the current transaction
 187          *
 188          * @var string[]
 189          */
 190         private $mTrxWriteCallers = [];
 191         /**
 192          * @var float Seconds spent in write queries for the current transaction
 193          */
 194         private $mTrxWriteDuration = 0.0;
 195         /**
 196          * @var integer Number of write queries for the current transaction
 197          */
 198         private $mTrxWriteQueryCount = 0;
 199         /**
 200          * @var float Like mTrxWriteQueryCount but excludes lock-bound, easy to replicate, queries
 201          */
 202         private $mTrxWriteAdjDuration = 0.0;
 203         /**
 204          * @var integer Number of write queries counted in mTrxWriteAdjDuration
 205          */
 206         private $mTrxWriteAdjQueryCount = 0;
 207         /**
 208          * @var float RTT time estimate
 209          */
 210         private $mRTTEstimate = 0.0;
 211
 212         /** @var array Map of (name => 1) for locks obtained via lock() */
 213         private $mNamedLocksHeld = [];
 214         /** @var array Map of (table name => 1) for TEMPORARY tables */
 215         protected $mSessionTempTables = [];
 216
 217         /** @var IDatabase|null Lazy handle to the master DB this server replicates from */
 218         private $lazyMasterHandle;
 219
 220         /** @var float UNIX timestamp */
 221         protected $lastPing = 0.0;
 222
 223         /** @var int[] Prior mFlags values */
 224         private $priorFlags = [];
 225
 226         /** @var object|string Class name or object With profileIn/profileOut methods */
 227         protected $profiler;
 228         /** @var TransactionProfiler */
 229         protected $trxProfiler;
 230
 231         /**
 232          * Constructor and database handle and attempt to connect to the DB server
 233          *
 234          * IDatabase classes should not be constructed directly in external
 235          * code. Database::factory() should be used instead.
 236          *
 237          * @param array $params Parameters passed from Database::factory()
 238          */
 239         function __construct( array $params ) {
 240                 $server = $params['host'];
 241                 $user = $params['user'];
 242                 $password = $params['password'];
 243                 $dbName = $params['dbname'];
 244
 245                 $this->mSchema = $params['schema'];
 246                 $this->mTablePrefix = $params['tablePrefix'];
 247
 248                 $this->cliMode = $params['cliMode'];
 249                 // Agent name is added to SQL queries in a comment, so make sure it can't break out
 250                 $this->agent = str_replace( '/', '-', $params['agent'] );
 251
 252                 $this->mFlags = $params['flags'];
 253                 if ( $this->mFlags & self::DBO_DEFAULT ) {
 254                         if ( $this->cliMode ) {
 255                                 $this->mFlags &= ~self::DBO_TRX;
 256                         } else {
 257                                 $this->mFlags |= self::DBO_TRX;
 258                         }
 259                 }
 260
 261                 $this->mSessionVars = $params['variables'];
 262
 263                 $this->srvCache = isset( $params['srvCache'] )
 264                         ? $params['srvCache']
 265                         : new HashBagOStuff();
 266
 267                 $this->profiler = $params['profiler'];
 268                 $this->trxProfiler = $params['trxProfiler'];
 269                 $this->connLogger = $params['connLogger'];
 270                 $this->queryLogger = $params['queryLogger'];
 271                 $this->errorLogger = $params['errorLogger'];
 272
 273                 // Set initial dummy domain until open() sets the final DB/prefix
 274                 $this->currentDomain = DatabaseDomain::newUnspecified();
 275
 276                 if ( $user ) {
 277                         $this->open( $server, $user, $password, $dbName );
 278                 } elseif ( $this->requiresDatabaseUser() ) {
 279                         throw new InvalidArgumentException( "No database user provided." );
 280                 }
 281
 282                 // Set the domain object after open() sets the relevant fields
 283                 if ( $this->mDBname != '' ) {
 284                         // Domains with server scope but a table prefix are not used by IDatabase classes
 285                         $this->currentDomain = new DatabaseDomain( $this->mDBname, null, $this->mTablePrefix );
 286                 }
 287         }
 288
 289         /**
 290          * Construct a Database subclass instance given a database type and parameters
 291          *
 292          * This also connects to the database immediately upon object construction
 293          *
 294          * @param string $dbType A possible DB type (sqlite, mysql, postgres)
 295          * @param array $p Parameter map with keys:
 296          *   - host : The hostname of the DB server
 297          *   - user : The name of the database user the client operates under
 298          *   - password : The password for the database user
 299          *   - dbname : The name of the database to use where queries do not specify one.
 300          *      The database must exist or an error might be thrown. Setting this to the empty string
 301          *      will avoid any such errors and make the handle have no implicit database scope. This is
 302          *      useful for queries like SHOW STATUS, CREATE DATABASE, or DROP DATABASE. Note that a
 303          *      "database" in Postgres is rougly equivalent to an entire MySQL server. This the domain
 304          *      in which user names and such are defined, e.g. users are database-specific in Postgres.
 305          *   - schema : The database schema to use (if supported). A "schema" in Postgres is roughly
 306          *      equivalent to a "database" in MySQL. Note that MySQL and SQLite do not use schemas.
 307          *   - tablePrefix : Optional table prefix that is implicitly added on to all table names
 308          *      recognized in queries. This can be used in place of schemas for handle site farms.
 309          *   - flags : Optional bitfield of DBO_* constants that define connection, protocol,
 310          *      buffering, and transaction behavior. It is STRONGLY adviced to leave the DBO_DEFAULT
 311          *      flag in place UNLESS this this database simply acts as a key/value store.
 312          *   - driver: Optional name of a specific DB client driver. For MySQL, there is the old
 313          *      'mysql' driver and the newer 'mysqli' driver.
 314          *   - variables: Optional map of session variables to set after connecting. This can be
 315          *      used to adjust lock timeouts or encoding modes and the like.
 316          *   - connLogger: Optional PSR-3 logger interface instance.
 317          *   - queryLogger: Optional PSR-3 logger interface instance.
 318          *   - profiler: Optional class name or object with profileIn()/profileOut() methods.
 319          *      These will be called in query(), using a simplified version of the SQL that also
 320          *      includes the agent as a SQL comment.
 321          *   - trxProfiler: Optional TransactionProfiler instance.
 322          *   - errorLogger: Optional callback that takes an Exception and logs it.
 323          *   - cliMode: Whether to consider the execution context that of a CLI script.
 324          *   - agent: Optional name used to identify the end-user in query profiling/logging.
 325          *   - srvCache: Optional BagOStuff instance to an APC-style cache.
 326          * @return Database|null If the database driver or extension cannot be found
 327          * @throws InvalidArgumentException If the database driver or extension cannot be found
 328          * @since 1.18
 329          */
 330         final public static function factory( $dbType, $p = [] ) {
 331                 static $canonicalDBTypes = [
 332                         'mysql' => [ 'mysqli', 'mysql' ],
 333                         'postgres' => [],
 334                         'sqlite' => [],
 335                         'oracle' => [],
 336                         'mssql' => [],
 337                 ];
 338
 339                 $driver = false;
 340                 $dbType = strtolower( $dbType );
 341                 if ( isset( $canonicalDBTypes[$dbType] ) && $canonicalDBTypes[$dbType] ) {
 342                         $possibleDrivers = $canonicalDBTypes[$dbType];
 343                         if ( !empty( $p['driver'] ) ) {
 344                                 if ( in_array( $p['driver'], $possibleDrivers ) ) {
 345                                         $driver = $p['driver'];
 346                                 } else {
 347                                         throw new InvalidArgumentException( __METHOD__ .
 348                                                 " type '$dbType' does not support driver '{$p['driver']}'" );
 349                                 }
 350                         } else {
 351                                 foreach ( $possibleDrivers as $posDriver ) {
 352                                         if ( extension_loaded( $posDriver ) ) {
 353                                                 $driver = $posDriver;
 354                                                 break;
 355                                         }
 356                                 }
 357                         }
 358                 } else {
 359                         $driver = $dbType;
 360                 }
 361                 if ( $driver === false || $driver === '' ) {
 362                         throw new InvalidArgumentException( __METHOD__ .
 363                                 " no viable database extension found for type '$dbType'" );
 364                 }
 365
 366                 $class = 'Database' . ucfirst( $driver );
 367                 if ( class_exists( $class ) && is_subclass_of( $class, 'IDatabase' ) ) {
 368                         // Resolve some defaults for b/c
 369                         $p['host'] = isset( $p['host'] ) ? $p['host'] : false;
 370                         $p['user'] = isset( $p['user'] ) ? $p['user'] : false;
 371                         $p['password'] = isset( $p['password'] ) ? $p['password'] : false;
 372                         $p['dbname'] = isset( $p['dbname'] ) ? $p['dbname'] : false;
 373                         $p['flags'] = isset( $p['flags'] ) ? $p['flags'] : 0;
 374                         $p['variables'] = isset( $p['variables'] ) ? $p['variables'] : [];
 375                         $p['tablePrefix'] = isset( $p['tablePrefix'] ) ? $p['tablePrefix'] : '';
 376                         $p['schema'] = isset( $p['schema'] ) ? $p['schema'] : '';
 377                         $p['cliMode'] = isset( $p['cliMode'] ) ? $p['cliMode'] : ( PHP_SAPI === 'cli' );
 378                         $p['agent'] = isset( $p['agent'] ) ? $p['agent'] : '';
 379                         if ( !isset( $p['connLogger'] ) ) {
 380                                 $p['connLogger'] = new \Psr\Log\NullLogger();
 381                         }
 382                         if ( !isset( $p['queryLogger'] ) ) {
 383                                 $p['queryLogger'] = new \Psr\Log\NullLogger();
 384                         }
 385                         $p['profiler'] = isset( $p['profiler'] ) ? $p['profiler'] : null;
 386                         if ( !isset( $p['trxProfiler'] ) ) {
 387                                 $p['trxProfiler'] = new TransactionProfiler();
 388                         }
 389                         if ( !isset( $p['errorLogger'] ) ) {
 390                                 $p['errorLogger'] = function ( Exception $e ) {
 391                                         trigger_error( get_class( $e ) . ': ' . $e->getMessage(), E_USER_WARNING );
 392                                 };
 393                         }
 394
 395                         $conn = new $class( $p );
 396                 } else {
 397                         $conn = null;
 398                 }
 399
 400                 return $conn;
 401         }
 402
 403         public function setLogger( LoggerInterface $logger ) {
 404                 $this->queryLogger = $logger;
 405         }
 406
 407         public function getServerInfo() {
 408                 return $this->getServerVersion();
 409         }
 410
 411         public function bufferResults( $buffer = null ) {
 412                 $res = !$this->getFlag( self::DBO_NOBUFFER );
 413                 if ( $buffer !== null ) {
 414                         $buffer
 415                                 ? $this->clearFlag( self::DBO_NOBUFFER )
 416                                 : $this->setFlag( self::DBO_NOBUFFER );
 417                 }
 418
 419                 return $res;
 420         }
 421
 422         /**
 423          * Turns on (false) or off (true) the automatic generation and sending
 424          * of a "we're sorry, but there has been a database error" page on
 425          * database errors. Default is on (false). When turned off, the
 426          * code should use lastErrno() and lastError() to handle the
 427          * situation as appropriate.
 428          *
 429          * Do not use this function outside of the Database classes.
 430          *
 431          * @param null|bool $ignoreErrors
 432          * @return bool The previous value of the flag.
 433          */
 434         protected function ignoreErrors( $ignoreErrors = null ) {
 435                 $res = $this->getFlag( self::DBO_IGNORE );
 436                 if ( $ignoreErrors !== null ) {
 437                         $ignoreErrors
 438                                 ? $this->setFlag( self::DBO_IGNORE )
 439                                 : $this->clearFlag( self::DBO_IGNORE );
 440                 }
 441
 442                 return $res;
 443         }
 444
 445         public function trxLevel() {
 446                 return $this->mTrxLevel;
 447         }
 448
 449         public function trxTimestamp() {
 450                 return $this->mTrxLevel ? $this->mTrxTimestamp : null;
 451         }
 452
 453         public function tablePrefix( $prefix = null ) {
 454                 $old = $this->mTablePrefix;
 455                 if ( $prefix !== null ) {
 456                         $this->mTablePrefix = $prefix;
 457                         $this->currentDomain = ( $this->mDBname != '' )
 458                                 ? new DatabaseDomain( $this->mDBname, null, $this->mTablePrefix )
 459                                 : DatabaseDomain::newUnspecified();
 460                 }
 461
 462                 return $old;
 463         }
 464
 465         public function dbSchema( $schema = null ) {
 466                 $old = $this->mSchema;
 467                 if ( $schema !== null ) {
 468                         $this->mSchema = $schema;
 469                 }
 470
 471                 return $old;
 472         }
 473
 474         public function getLBInfo( $name = null ) {
 475                 if ( is_null( $name ) ) {
 476                         return $this->mLBInfo;
 477                 } else {
 478                         if ( array_key_exists( $name, $this->mLBInfo ) ) {
 479                                 return $this->mLBInfo[$name];
 480                         } else {
 481                                 return null;
 482                         }
 483                 }
 484         }
 485
 486         public function setLBInfo( $name, $value = null ) {
 487                 if ( is_null( $value ) ) {
 488                         $this->mLBInfo = $name;
 489                 } else {
 490                         $this->mLBInfo[$name] = $value;
 491                 }
 492         }
 493
 494         public function setLazyMasterHandle( IDatabase $conn ) {
 495                 $this->lazyMasterHandle = $conn;
 496         }
 497
 498         /**
 499          * @return IDatabase|null
 500          * @see setLazyMasterHandle()
 501          * @since 1.27
 502          */
 503         protected function getLazyMasterHandle() {
 504                 return $this->lazyMasterHandle;
 505         }
 506
 507         public function implicitGroupby() {
 508                 return true;
 509         }
 510
 511         public function implicitOrderby() {
 512                 return true;
 513         }
 514
 515         public function lastQuery() {
 516                 return $this->mLastQuery;
 517         }
 518
 519         public function doneWrites() {
 520                 return (bool)$this->mLastWriteTime;
 521         }
 522
 523         public function lastDoneWrites() {
 524                 return $this->mLastWriteTime ?: false;
 525         }
 526
 527         public function writesPending() {
 528                 return $this->mTrxLevel && $this->mTrxDoneWrites;
 529         }
 530
 531         public function writesOrCallbacksPending() {
 532                 return $this->mTrxLevel && (
 533                         $this->mTrxDoneWrites || $this->mTrxIdleCallbacks || $this->mTrxPreCommitCallbacks
 534                 );
 535         }
 536
 537         public function pendingWriteQueryDuration( $type = self::ESTIMATE_TOTAL ) {
 538                 if ( !$this->mTrxLevel ) {
 539                         return false;
 540                 } elseif ( !$this->mTrxDoneWrites ) {
 541                         return 0.0;
 542                 }
 543
 544                 switch ( $type ) {
 545                         case self::ESTIMATE_DB_APPLY:
 546                                 $this->ping( $rtt );
 547                                 $rttAdjTotal = $this->mTrxWriteAdjQueryCount * $rtt;
 548                                 $applyTime = max( $this->mTrxWriteAdjDuration - $rttAdjTotal, 0 );
 549                                 // For omitted queries, make them count as something at least
 550                                 $omitted = $this->mTrxWriteQueryCount - $this->mTrxWriteAdjQueryCount;
 551                                 $applyTime += self::TINY_WRITE_SEC * $omitted;
 552
 553                                 return $applyTime;
 554                         default: // everything
 555                                 return $this->mTrxWriteDuration;
 556                 }
 557         }
 558
 559         public function pendingWriteCallers() {
 560                 return $this->mTrxLevel ? $this->mTrxWriteCallers : [];
 561         }
 562
 563         protected function pendingWriteAndCallbackCallers() {
 564                 if ( !$this->mTrxLevel ) {
 565                         return [];
 566                 }
 567
 568                 $fnames = $this->mTrxWriteCallers;
 569                 foreach ( [
 570                         $this->mTrxIdleCallbacks,
 571                         $this->mTrxPreCommitCallbacks,
 572                         $this->mTrxEndCallbacks
 573                 ] as $callbacks ) {
 574                         foreach ( $callbacks as $callback ) {
 575                                 $fnames[] = $callback[1];
 576                         }
 577                 }
 578
 579                 return $fnames;
 580         }
 581
 582         public function isOpen() {
 583                 return $this->mOpened;
 584         }
 585
 586         public function setFlag( $flag, $remember = self::REMEMBER_NOTHING ) {
 587                 if ( $remember === self::REMEMBER_PRIOR ) {
 588                         array_push( $this->priorFlags, $this->mFlags );
 589                 }
 590                 $this->mFlags |= $flag;
 591         }
 592
 593         public function clearFlag( $flag, $remember = self::REMEMBER_NOTHING ) {
 594                 if ( $remember === self::REMEMBER_PRIOR ) {
 595                         array_push( $this->priorFlags, $this->mFlags );
 596                 }
 597                 $this->mFlags &= ~$flag;
 598         }
 599
 600         public function restoreFlags( $state = self::RESTORE_PRIOR ) {
 601                 if ( !$this->priorFlags ) {
 602                         return;
 603                 }
 604
 605                 if ( $state === self::RESTORE_INITIAL ) {
 606                         $this->mFlags = reset( $this->priorFlags );
 607                         $this->priorFlags = [];
 608                 } else {
 609                         $this->mFlags = array_pop( $this->priorFlags );
 610                 }
 611         }
 612
 613         public function getFlag( $flag ) {
 614                 return !!( $this->mFlags & $flag );
 615         }
 616
 617         /**
 618          * @param string $name Class field name
 619          * @return mixed
 620          * @deprecated Since 1.28
 621          */
 622         public function getProperty( $name ) {
 623                 return $this->$name;
 624         }
 625
 626         public function getDomainID() {
 627                 return $this->currentDomain->getId();
 628         }
 629
 630         final public function getWikiID() {
 631                 return $this->getDomainID();
 632         }
 633
 634         /**
 635          * Get information about an index into an object
 636          * @param string $table Table name
 637          * @param string $index Index name
 638          * @param string $fname Calling function name
 639          * @return mixed Database-specific index description class or false if the index does not exist
 640          */
 641         abstract function indexInfo( $table, $index, $fname = __METHOD__ );
 642
 643         /**
 644          * Wrapper for addslashes()
 645          *
 646          * @param string $s String to be slashed.
 647          * @return string Slashed string.
 648          */
 649         abstract function strencode( $s );
 650
 651         protected function installErrorHandler() {
 652                 $this->mPHPError = false;
 653                 $this->htmlErrors = ini_set( 'html_errors', '0' );
 654                 set_error_handler( [ $this, 'connectionErrorLogger' ] );
 655         }
 656
 657         /**
 658          * @return bool|string
 659          */
 660         protected function restoreErrorHandler() {
 661                 restore_error_handler();
 662                 if ( $this->htmlErrors !== false ) {
 663                         ini_set( 'html_errors', $this->htmlErrors );
 664                 }
 665
 666                 return $this->getLastPHPError();
 667         }
 668
 669         /**
 670          * @return string|bool Last PHP error for this DB (typically connection errors)
 671          */
 672         protected function getLastPHPError() {
 673                 if ( $this->mPHPError ) {
 674                         $error = preg_replace( '!\[<a.*</a>\]!', '', $this->mPHPError );
 675                         $error = preg_replace( '!^.*?:\s?(.*)$!', '$1', $error );
 676
 677                         return $error;
 678                 }
 679
 680                 return false;
 681         }
 682
 683         /**
 684          * This method should not be used outside of Database classes
 685          *
 686          * @param int $errno
 687          * @param string $errstr
 688          */
 689         public function connectionErrorLogger( $errno, $errstr ) {
 690                 $this->mPHPError = $errstr;
 691         }
 692
 693         /**
 694          * Create a log context to pass to PSR-3 logger functions.
 695          *
 696          * @param array $extras Additional data to add to context
 697          * @return array
 698          */
 699         protected function getLogContext( array $extras = [] ) {
 700                 return array_merge(
 701                         [
 702                                 'db_server' => $this->mServer,
 703                                 'db_name' => $this->mDBname,
 704                                 'db_user' => $this->mUser,
 705                         ],
 706                         $extras
 707                 );
 708         }
 709
 710         public function close() {
 711                 if ( $this->mConn ) {
 712                         if ( $this->trxLevel() ) {
 713                                 $this->commit( __METHOD__, self::FLUSHING_INTERNAL );
 714                         }
 715
 716                         $closed = $this->closeConnection();
 717                         $this->mConn = false;
 718                 } elseif ( $this->mTrxIdleCallbacks || $this->mTrxEndCallbacks ) { // sanity
 719                         throw new RuntimeException( "Transaction callbacks still pending." );
 720                 } else {
 721                         $closed = true;
 722                 }
 723                 $this->mOpened = false;
 724
 725                 return $closed;
 726         }
 727
 728         /**
 729          * Make sure isOpen() returns true as a sanity check
 730          *
 731          * @throws DBUnexpectedError
 732          */
 733         protected function assertOpen() {
 734                 if ( !$this->isOpen() ) {
 735                         throw new DBUnexpectedError( $this, "DB connection was already closed." );
 736                 }
 737         }
 738
 739         /**
 740          * Closes underlying database connection
 741          * @since 1.20
 742          * @return bool Whether connection was closed successfully
 743          */
 744         abstract protected function closeConnection();
 745
 746         public function reportConnectionError( $error = 'Unknown error' ) {
 747                 $myError = $this->lastError();
 748                 if ( $myError ) {
 749                         $error = $myError;
 750                 }
 751
 752                 # New method
 753                 throw new DBConnectionError( $this, $error );
 754         }
 755
 756         /**
 757          * The DBMS-dependent part of query()
 758          *
 759          * @param string $sql SQL query.
 760          * @return ResultWrapper|bool Result object to feed to fetchObject,
 761          *   fetchRow, ...; or false on failure
 762          */
 763         abstract protected function doQuery( $sql );
 764
 765         /**
 766          * Determine whether a query writes to the DB.
 767          * Should return true if unsure.
 768          *
 769          * @param string $sql
 770          * @return bool
 771          */
 772         protected function isWriteQuery( $sql ) {
 773                 return !preg_match(
 774                         '/^(?:SELECT|BEGIN|ROLLBACK|COMMIT|SET|SHOW|EXPLAIN|\(SELECT)\b/i', $sql );
 775         }
 776
 777         /**
 778          * @param $sql
 779          * @return string|null
 780          */
 781         protected function getQueryVerb( $sql ) {
 782                 return preg_match( '/^\s*([a-z]+)/i', $sql, $m ) ? strtoupper( $m[1] ) : null;
 783         }
 784
 785         /**
 786          * Determine whether a SQL statement is sensitive to isolation level.
 787          * A SQL statement is considered transactable if its result could vary
 788          * depending on the transaction isolation level. Operational commands
 789          * such as 'SET' and 'SHOW' are not considered to be transactable.
 790          *
 791          * @param string $sql
 792          * @return bool
 793          */
 794         protected function isTransactableQuery( $sql ) {
 795                 return !in_array(
 796                         $this->getQueryVerb( $sql ),
 797                         [ 'BEGIN', 'COMMIT', 'ROLLBACK', 'SHOW', 'SET', 'CREATE', 'ALTER' ],
 798                         true
 799                 );
 800         }
 801
 802         /**
 803          * @param string $sql A SQL query
 804          * @return bool Whether $sql is SQL for creating/dropping a new TEMPORARY table
 805          */
 806         protected function registerTempTableOperation( $sql ) {
 807                 if ( preg_match(
 808                         '/^CREATE\s+TEMPORARY\s+TABLE\s+(?:IF\s+NOT\s+EXISTS\s+)?[`"\']?(\w+)[`"\']?/i',
 809                         $sql,
 810                         $matches
 811                 ) ) {
 812                         $this->mSessionTempTables[$matches[1]] = 1;
 813
 814                         return true;
 815                 } elseif ( preg_match(
 816                         '/^DROP\s+(?:TEMPORARY\s+)?TABLE\s+(?:IF\s+EXISTS\s+)?[`"\']?(\w+)[`"\']?/i',
 817                         $sql,
 818                         $matches
 819                 ) ) {
 820                         unset( $this->mSessionTempTables[$matches[1]] );
 821
 822                         return true;
 823                 } elseif ( preg_match(
 824                         '/^(?:INSERT\s+(?:\w+\s+)?INTO|UPDATE|DELETE\s+FROM)\s+[`"\']?(\w+)[`"\']?/i',
 825                         $sql,
 826                         $matches
 827                 ) ) {
 828                         return isset( $this->mSessionTempTables[$matches[1]] );
 829                 }
 830
 831                 return false;
 832         }
 833
 834         public function query( $sql, $fname = __METHOD__, $tempIgnore = false ) {
 835                 $priorWritesPending = $this->writesOrCallbacksPending();
 836                 $this->mLastQuery = $sql;
 837
 838                 $isWrite = $this->isWriteQuery( $sql ) && !$this->registerTempTableOperation( $sql );
 839                 if ( $isWrite ) {
 840                         $reason = $this->getReadOnlyReason();
 841                         if ( $reason !== false ) {
 842                                 throw new DBReadOnlyError( $this, "Database is read-only: $reason" );
 843                         }
 844                         # Set a flag indicating that writes have been done
 845                         $this->mLastWriteTime = microtime( true );
 846                 }
 847
 848                 // Add trace comment to the begin of the sql string, right after the operator.
 849                 // Or, for one-word queries (like "BEGIN" or COMMIT") add it to the end (bug 42598)
 850                 $commentedSql = preg_replace( '/\s|$/', " /* $fname {$this->agent} */ ", $sql, 1 );
 851
 852                 # Start implicit transactions that wrap the request if DBO_TRX is enabled
 853                 if ( !$this->mTrxLevel && $this->getFlag( self::DBO_TRX )
 854                         && $this->isTransactableQuery( $sql )
 855                 ) {
 856                         $this->begin( __METHOD__ . " ($fname)", self::TRANSACTION_INTERNAL );
 857                         $this->mTrxAutomatic = true;
 858                 }
 859
 860                 # Keep track of whether the transaction has write queries pending
 861                 if ( $this->mTrxLevel && !$this->mTrxDoneWrites && $isWrite ) {
 862                         $this->mTrxDoneWrites = true;
 863                         $this->trxProfiler->transactionWritingIn(
 864                                 $this->mServer, $this->mDBname, $this->mTrxShortId );
 865                 }
 866
 867                 if ( $this->getFlag( self::DBO_DEBUG ) ) {
 868                         $this->queryLogger->debug( "{$this->mDBname} {$commentedSql}" );
 869                 }
 870
 871                 # Avoid fatals if close() was called
 872                 $this->assertOpen();
 873
 874                 # Send the query to the server
 875                 $ret = $this->doProfiledQuery( $sql, $commentedSql, $isWrite, $fname );
 876
 877                 # Try reconnecting if the connection was lost
 878                 if ( false === $ret && $this->wasErrorReissuable() ) {
 879                         $recoverable = $this->canRecoverFromDisconnect( $sql, $priorWritesPending );
 880                         # Stash the last error values before anything might clear them
 881                         $lastError = $this->lastError();
 882                         $lastErrno = $this->lastErrno();
 883                         # Update state tracking to reflect transaction loss due to disconnection
 884                         $this->handleSessionLoss();
 885                         if ( $this->reconnect() ) {
 886                                 $msg = __METHOD__ . ": lost connection to {$this->getServer()}; reconnected";
 887                                 $this->connLogger->warning( $msg );
 888                                 $this->queryLogger->warning(
 889                                         "$msg:\n" . ( new RuntimeException() )->getTraceAsString() );
 890
 891                                 if ( !$recoverable ) {
 892                                         # Callers may catch the exception and continue to use the DB
 893                                         $this->reportQueryError( $lastError, $lastErrno, $sql, $fname );
 894                                 } else {
 895                                         # Should be safe to silently retry the query
 896                                         $ret = $this->doProfiledQuery( $sql, $commentedSql, $isWrite, $fname );
 897                                 }
 898                         } else {
 899                                 $msg = __METHOD__ . ": lost connection to {$this->getServer()} permanently";
 900                                 $this->connLogger->error( $msg );
 901                         }
 902                 }
 903
 904                 if ( false === $ret ) {
 905                         # Deadlocks cause the entire transaction to abort, not just the statement.
 906                         # https://dev.mysql.com/doc/refman/5.7/en/innodb-error-handling.html
 907                         # https://www.postgresql.org/docs/9.1/static/explicit-locking.html
 908                         if ( $this->wasDeadlock() ) {
 909                                 if ( $this->explicitTrxActive() || $priorWritesPending ) {
 910                                         $tempIgnore = false; // not recoverable
 911                                 }
 912                                 # Update state tracking to reflect transaction loss
 913                                 $this->handleSessionLoss();
 914                         }
 915
 916                         $this->reportQueryError(
 917                                 $this->lastError(), $this->lastErrno(), $sql, $fname, $tempIgnore );
 918                 }
 919
 920                 $res = $this->resultObject( $ret );
 921
 922                 return $res;
 923         }
 924
 925         private function doProfiledQuery( $sql, $commentedSql, $isWrite, $fname ) {
 926                 $isMaster = !is_null( $this->getLBInfo( 'master' ) );
 927                 # generalizeSQL() will probably cut down the query to reasonable
 928                 # logging size most of the time. The substr is really just a sanity check.
 929                 if ( $isMaster ) {
 930                         $queryProf = 'query-m: ' . substr( self::generalizeSQL( $sql ), 0, 255 );
 931                 } else {
 932                         $queryProf = 'query: ' . substr( self::generalizeSQL( $sql ), 0, 255 );
 933                 }
 934
 935                 # Include query transaction state
 936                 $queryProf .= $this->mTrxShortId ? " [TRX#{$this->mTrxShortId}]" : "";
 937
 938                 $startTime = microtime( true );
 939                 if ( $this->profiler ) {
 940                         call_user_func( [ $this->profiler, 'profileIn' ], $queryProf );
 941                 }
 942                 $ret = $this->doQuery( $commentedSql );
 943                 if ( $this->profiler ) {
 944                         call_user_func( [ $this->profiler, 'profileOut' ], $queryProf );
 945                 }
 946                 $queryRuntime = max( microtime( true ) - $startTime, 0.0 );
 947
 948                 unset( $queryProfSection ); // profile out (if set)
 949
 950                 if ( $ret !== false ) {
 951                         $this->lastPing = $startTime;
 952                         if ( $isWrite && $this->mTrxLevel ) {
 953                                 $this->updateTrxWriteQueryTime( $sql, $queryRuntime );
 954                                 $this->mTrxWriteCallers[] = $fname;
 955                         }
 956                 }
 957
 958                 if ( $sql === self::PING_QUERY ) {
 959                         $this->mRTTEstimate = $queryRuntime;
 960                 }
 961
 962                 $this->trxProfiler->recordQueryCompletion(
 963                         $queryProf, $startTime, $isWrite, $this->affectedRows()
 964                 );
 965                 $this->queryLogger->debug( $sql, [
 966                         'method' => $fname,
 967                         'master' => $isMaster,
 968                         'runtime' => $queryRuntime,
 969                 ] );
 970
 971                 return $ret;
 972         }
 973
 974         /**
 975          * Update the estimated run-time of a query, not counting large row lock times
 976          *
 977          * LoadBalancer can be set to rollback transactions that will create huge replication
 978          * lag. It bases this estimate off of pendingWriteQueryDuration(). Certain simple
 979          * queries, like inserting a row can take a long time due to row locking. This method
 980          * uses some simple heuristics to discount those cases.
 981          *
 982          * @param string $sql A SQL write query
 983          * @param float $runtime Total runtime, including RTT
 984          */
 985         private function updateTrxWriteQueryTime( $sql, $runtime ) {
 986                 // Whether this is indicative of replica DB runtime (except for RBR or ws_repl)
 987                 $indicativeOfReplicaRuntime = true;
 988                 if ( $runtime > self::SLOW_WRITE_SEC ) {
 989                         $verb = $this->getQueryVerb( $sql );
 990                         // insert(), upsert(), replace() are fast unless bulky in size or blocked on locks
 991                         if ( $verb === 'INSERT' ) {
 992                                 $indicativeOfReplicaRuntime = $this->affectedRows() > self::SMALL_WRITE_ROWS;
 993                         } elseif ( $verb === 'REPLACE' ) {
 994                                 $indicativeOfReplicaRuntime = $this->affectedRows() > self::SMALL_WRITE_ROWS / 2;
 995                         }
 996                 }
 997
 998                 $this->mTrxWriteDuration += $runtime;
 999                 $this->mTrxWriteQueryCount += 1;
1000                 if ( $indicativeOfReplicaRuntime ) {
1001                         $this->mTrxWriteAdjDuration += $runtime;
1002                         $this->mTrxWriteAdjQueryCount += 1;
1003                 }
1004         }
1005
1006         private function canRecoverFromDisconnect( $sql, $priorWritesPending ) {
1007                 # Transaction dropped; this can mean lost writes, or REPEATABLE-READ snapshots.
1008                 # Dropped connections also mean that named locks are automatically released.
1009                 # Only allow error suppression in autocommit mode or when the lost transaction
1010                 # didn't matter anyway (aside from DBO_TRX snapshot loss).
1011                 if ( $this->mNamedLocksHeld ) {
1012                         return false; // possible critical section violation
1013                 } elseif ( $sql === 'COMMIT' ) {
1014                         return !$priorWritesPending; // nothing written anyway? (T127428)
1015                 } elseif ( $sql === 'ROLLBACK' ) {
1016                         return true; // transaction lost...which is also what was requested :)
1017                 } elseif ( $this->explicitTrxActive() ) {
1018                         return false; // don't drop atomocity
1019                 } elseif ( $priorWritesPending ) {
1020                         return false; // prior writes lost from implicit transaction
1021                 }
1022
1023                 return true;
1024         }
1025
1026         private function handleSessionLoss() {
1027                 $this->mTrxLevel = 0;
1028                 $this->mTrxIdleCallbacks = []; // bug 65263
1029                 $this->mTrxPreCommitCallbacks = []; // bug 65263
1030                 $this->mSessionTempTables = [];
1031                 $this->mNamedLocksHeld = [];
1032                 try {
1033                         // Handle callbacks in mTrxEndCallbacks
1034                         $this->runOnTransactionIdleCallbacks( self::TRIGGER_ROLLBACK );
1035                         $this->runTransactionListenerCallbacks( self::TRIGGER_ROLLBACK );
1036                         return null;
1037                 } catch ( Exception $e ) {
1038                         // Already logged; move on...
1039                         return $e;
1040                 }
1041         }
1042
1043         public function reportQueryError( $error, $errno, $sql, $fname, $tempIgnore = false ) {
1044                 if ( $this->ignoreErrors() || $tempIgnore ) {
1045                         $this->queryLogger->debug( "SQL ERROR (ignored): $error\n" );
1046                 } else {
1047                         $sql1line = mb_substr( str_replace( "\n", "\\n", $sql ), 0, 5 * 1024 );
1048                         $this->queryLogger->error(
1049                                 "{fname}\t{db_server}\t{errno}\t{error}\t{sql1line}",
1050                                 $this->getLogContext( [
1051                                         'method' => __METHOD__,
1052                                         'errno' => $errno,
1053                                         'error' => $error,
1054                                         'sql1line' => $sql1line,
1055                                         'fname' => $fname,
1056                                 ] )
1057                         );
1058                         $this->queryLogger->debug( "SQL ERROR: " . $error . "\n" );
1059                         throw new DBQueryError( $this, $error, $errno, $sql, $fname );
1060                 }
1061         }
1062
1063         public function freeResult( $res ) {
1064         }
1065
1066         public function selectField(
1067                 $table, $var, $cond = '', $fname = __METHOD__, $options = []
1068         ) {
1069                 if ( $var === '*' ) { // sanity
1070                         throw new DBUnexpectedError( $this, "Cannot use a * field: got '$var'" );
1071                 }
1072
1073                 if ( !is_array( $options ) ) {
1074                         $options = [ $options ];
1075                 }
1076
1077                 $options['LIMIT'] = 1;
1078
1079                 $res = $this->select( $table, $var, $cond, $fname, $options );
1080                 if ( $res === false || !$this->numRows( $res ) ) {
1081                         return false;
1082                 }
1083
1084                 $row = $this->fetchRow( $res );
1085
1086                 if ( $row !== false ) {
1087                         return reset( $row );
1088                 } else {
1089                         return false;
1090                 }
1091         }
1092
1093         public function selectFieldValues(
1094                 $table, $var, $cond = '', $fname = __METHOD__, $options = [], $join_conds = []
1095         ) {
1096                 if ( $var === '*' ) { // sanity
1097                         throw new DBUnexpectedError( $this, "Cannot use a * field" );
1098                 } elseif ( !is_string( $var ) ) { // sanity
1099                         throw new DBUnexpectedError( $this, "Cannot use an array of fields" );
1100                 }
1101
1102                 if ( !is_array( $options ) ) {
1103                         $options = [ $options ];
1104                 }
1105
1106                 $res = $this->select( $table, $var, $cond, $fname, $options, $join_conds );
1107                 if ( $res === false ) {
1108                         return false;
1109                 }
1110
1111                 $values = [];
1112                 foreach ( $res as $row ) {
1113                         $values[] = $row->$var;
1114                 }
1115
1116                 return $values;
1117         }
1118
1119         /**
1120          * Returns an optional USE INDEX clause to go after the table, and a
1121          * string to go at the end of the query.
1122          *
1123          * @param array $options Associative array of options to be turned into
1124          *   an SQL query, valid keys are listed in the function.
1125          * @return array
1126          * @see Database::select()
1127          */
1128         protected function makeSelectOptions( $options ) {
1129                 $preLimitTail = $postLimitTail = '';
1130                 $startOpts = '';
1131
1132                 $noKeyOptions = [];
1133
1134                 foreach ( $options as $key => $option ) {
1135                         if ( is_numeric( $key ) ) {
1136                                 $noKeyOptions[$option] = true;
1137                         }
1138                 }
1139
1140                 $preLimitTail .= $this->makeGroupByWithHaving( $options );
1141
1142                 $preLimitTail .= $this->makeOrderBy( $options );
1143
1144                 // if (isset($options['LIMIT'])) {
1145                 //      $tailOpts .= $this->limitResult('', $options['LIMIT'],
1146                 //              isset($options['OFFSET']) ? $options['OFFSET']
1147                 //              : false);
1148                 // }
1149
1150                 if ( isset( $noKeyOptions['FOR UPDATE'] ) ) {
1151                         $postLimitTail .= ' FOR UPDATE';
1152                 }
1153
1154                 if ( isset( $noKeyOptions['LOCK IN SHARE MODE'] ) ) {
1155                         $postLimitTail .= ' LOCK IN SHARE MODE';
1156                 }
1157
1158                 if ( isset( $noKeyOptions['DISTINCT'] ) || isset( $noKeyOptions['DISTINCTROW'] ) ) {
1159                         $startOpts .= 'DISTINCT';
1160                 }
1161
1162                 # Various MySQL extensions
1163                 if ( isset( $noKeyOptions['STRAIGHT_JOIN'] ) ) {
1164                         $startOpts .= ' /*! STRAIGHT_JOIN */';
1165                 }
1166
1167                 if ( isset( $noKeyOptions['HIGH_PRIORITY'] ) ) {
1168                         $startOpts .= ' HIGH_PRIORITY';
1169                 }
1170
1171                 if ( isset( $noKeyOptions['SQL_BIG_RESULT'] ) ) {
1172                         $startOpts .= ' SQL_BIG_RESULT';
1173                 }
1174
1175                 if ( isset( $noKeyOptions['SQL_BUFFER_RESULT'] ) ) {
1176                         $startOpts .= ' SQL_BUFFER_RESULT';
1177                 }
1178
1179                 if ( isset( $noKeyOptions['SQL_SMALL_RESULT'] ) ) {
1180                         $startOpts .= ' SQL_SMALL_RESULT';
1181                 }
1182
1183                 if ( isset( $noKeyOptions['SQL_CALC_FOUND_ROWS'] ) ) {
1184                         $startOpts .= ' SQL_CALC_FOUND_ROWS';
1185                 }
1186
1187                 if ( isset( $noKeyOptions['SQL_CACHE'] ) ) {
1188                         $startOpts .= ' SQL_CACHE';
1189                 }
1190
1191                 if ( isset( $noKeyOptions['SQL_NO_CACHE'] ) ) {
1192                         $startOpts .= ' SQL_NO_CACHE';
1193                 }
1194
1195                 if ( isset( $options['USE INDEX'] ) && is_string( $options['USE INDEX'] ) ) {
1196                         $useIndex = $this->useIndexClause( $options['USE INDEX'] );
1197                 } else {
1198                         $useIndex = '';
1199                 }
1200                 if ( isset( $options['IGNORE INDEX'] ) && is_string( $options['IGNORE INDEX'] ) ) {
1201                         $ignoreIndex = $this->ignoreIndexClause( $options['IGNORE INDEX'] );
1202                 } else {
1203                         $ignoreIndex = '';
1204                 }
1205
1206                 return [ $startOpts, $useIndex, $preLimitTail, $postLimitTail, $ignoreIndex ];
1207         }
1208
1209         /**
1210          * Returns an optional GROUP BY with an optional HAVING
1211          *
1212          * @param array $options Associative array of options
1213          * @return string
1214          * @see Database::select()
1215          * @since 1.21
1216          */
1217         protected function makeGroupByWithHaving( $options ) {
1218                 $sql = '';
1219                 if ( isset( $options['GROUP BY'] ) ) {
1220                         $gb = is_array( $options['GROUP BY'] )
1221                                 ? implode( ',', $options['GROUP BY'] )
1222                                 : $options['GROUP BY'];
1223                         $sql .= ' GROUP BY ' . $gb;
1224                 }
1225                 if ( isset( $options['HAVING'] ) ) {
1226                         $having = is_array( $options['HAVING'] )
1227                                 ? $this->makeList( $options['HAVING'], self::LIST_AND )
1228                                 : $options['HAVING'];
1229                         $sql .= ' HAVING ' . $having;
1230                 }
1231
1232                 return $sql;
1233         }
1234
1235         /**
1236          * Returns an optional ORDER BY
1237          *
1238          * @param array $options Associative array of options
1239          * @return string
1240          * @see Database::select()
1241          * @since 1.21
1242          */
1243         protected function makeOrderBy( $options ) {
1244                 if ( isset( $options['ORDER BY'] ) ) {
1245                         $ob = is_array( $options['ORDER BY'] )
1246                                 ? implode( ',', $options['ORDER BY'] )
1247                                 : $options['ORDER BY'];
1248
1249                         return ' ORDER BY ' . $ob;
1250                 }
1251
1252                 return '';
1253         }
1254
1255         public function select( $table, $vars, $conds = '', $fname = __METHOD__,
1256                 $options = [], $join_conds = [] ) {
1257                 $sql = $this->selectSQLText( $table, $vars, $conds, $fname, $options, $join_conds );
1258
1259                 return $this->query( $sql, $fname );
1260         }
1261
1262         public function selectSQLText( $table, $vars, $conds = '', $fname = __METHOD__,
1263                 $options = [], $join_conds = []
1264         ) {
1265                 if ( is_array( $vars ) ) {
1266                         $vars = implode( ',', $this->fieldNamesWithAlias( $vars ) );
1267                 }
1268
1269                 $options = (array)$options;
1270                 $useIndexes = ( isset( $options['USE INDEX'] ) && is_array( $options['USE INDEX'] ) )
1271                         ? $options['USE INDEX']
1272                         : [];
1273                 $ignoreIndexes = (
1274                         isset( $options['IGNORE INDEX'] ) &&
1275                         is_array( $options['IGNORE INDEX'] )
1276                 )
1277                         ? $options['IGNORE INDEX']
1278                         : [];
1279
1280                 if ( is_array( $table ) ) {
1281                         $from = ' FROM ' .
1282                                 $this->tableNamesWithIndexClauseOrJOIN(
1283                                         $table, $useIndexes, $ignoreIndexes, $join_conds );
1284                 } elseif ( $table != '' ) {
1285                         if ( $table[0] == ' ' ) {
1286                                 $from = ' FROM ' . $table;
1287                         } else {
1288                                 $from = ' FROM ' .
1289                                         $this->tableNamesWithIndexClauseOrJOIN(
1290                                                 [ $table ], $useIndexes, $ignoreIndexes, [] );
1291                         }
1292                 } else {
1293                         $from = '';
1294                 }
1295
1296                 list( $startOpts, $useIndex, $preLimitTail, $postLimitTail, $ignoreIndex ) =
1297                         $this->makeSelectOptions( $options );
1298
1299                 if ( !empty( $conds ) ) {
1300                         if ( is_array( $conds ) ) {
1301                                 $conds = $this->makeList( $conds, self::LIST_AND );
1302                         }
1303                         $sql = "SELECT $startOpts $vars $from $useIndex $ignoreIndex " .
1304                                 "WHERE $conds $preLimitTail";
1305                 } else {
1306                         $sql = "SELECT $startOpts $vars $from $useIndex $ignoreIndex $preLimitTail";
1307                 }
1308
1309                 if ( isset( $options['LIMIT'] ) ) {
1310                         $sql = $this->limitResult( $sql, $options['LIMIT'],
1311                                 isset( $options['OFFSET'] ) ? $options['OFFSET'] : false );
1312                 }
1313                 $sql = "$sql $postLimitTail";
1314
1315                 if ( isset( $options['EXPLAIN'] ) ) {
1316                         $sql = 'EXPLAIN ' . $sql;
1317                 }
1318
1319                 return $sql;
1320         }
1321
1322         public function selectRow( $table, $vars, $conds, $fname = __METHOD__,
1323                 $options = [], $join_conds = []
1324         ) {
1325                 $options = (array)$options;
1326                 $options['LIMIT'] = 1;
1327                 $res = $this->select( $table, $vars, $conds, $fname, $options, $join_conds );
1328
1329                 if ( $res === false ) {
1330                         return false;
1331                 }
1332
1333                 if ( !$this->numRows( $res ) ) {
1334                         return false;
1335                 }
1336
1337                 $obj = $this->fetchObject( $res );
1338
1339                 return $obj;
1340         }
1341
1342         public function estimateRowCount(
1343                 $table, $vars = '*', $conds = '', $fname = __METHOD__, $options = []
1344         ) {
1345                 $rows = 0;
1346                 $res = $this->select( $table, [ 'rowcount' => 'COUNT(*)' ], $conds, $fname, $options );
1347
1348                 if ( $res ) {
1349                         $row = $this->fetchRow( $res );
1350                         $rows = ( isset( $row['rowcount'] ) ) ? (int)$row['rowcount'] : 0;
1351                 }
1352
1353                 return $rows;
1354         }
1355
1356         public function selectRowCount(
1357                 $tables, $vars = '*', $conds = '', $fname = __METHOD__, $options = [], $join_conds = []
1358         ) {
1359                 $rows = 0;
1360                 $sql = $this->selectSQLText( $tables, '1', $conds, $fname, $options, $join_conds );
1361                 $res = $this->query( "SELECT COUNT(*) AS rowcount FROM ($sql) tmp_count", $fname );
1362
1363                 if ( $res ) {
1364                         $row = $this->fetchRow( $res );
1365                         $rows = ( isset( $row['rowcount'] ) ) ? (int)$row['rowcount'] : 0;
1366                 }
1367
1368                 return $rows;
1369         }
1370
1371         /**
1372          * Removes most variables from an SQL query and replaces them with X or N for numbers.
1373          * It's only slightly flawed. Don't use for anything important.
1374          *
1375          * @param string $sql A SQL Query
1376          *
1377          * @return string
1378          */
1379         protected static function generalizeSQL( $sql ) {
1380                 # This does the same as the regexp below would do, but in such a way
1381                 # as to avoid crashing php on some large strings.
1382                 # $sql = preg_replace( "/'([^\\\\']|\\\\.)*'|\"([^\\\\\"]|\\\\.)*\"/", "'X'", $sql );
1383
1384                 $sql = str_replace( "\\\\", '', $sql );
1385                 $sql = str_replace( "\\'", '', $sql );
1386                 $sql = str_replace( "\\\"", '', $sql );
1387                 $sql = preg_replace( "/'.*'/s", "'X'", $sql );
1388                 $sql = preg_replace( '/".*"/s', "'X'", $sql );
1389
1390                 # All newlines, tabs, etc replaced by single space
1391                 $sql = preg_replace( '/\s+/', ' ', $sql );
1392
1393                 # All numbers => N,
1394                 # except the ones surrounded by characters, e.g. l10n
1395                 $sql = preg_replace( '/-?\d+(,-?\d+)+/s', 'N,...,N', $sql );
1396                 $sql = preg_replace( '/(?<![a-zA-Z])-?\d+(?![a-zA-Z])/s', 'N', $sql );
1397
1398                 return $sql;
1399         }
1400
1401         public function fieldExists( $table, $field, $fname = __METHOD__ ) {
1402                 $info = $this->fieldInfo( $table, $field );
1403
1404                 return (bool)$info;
1405         }
1406
1407         public function indexExists( $table, $index, $fname = __METHOD__ ) {
1408                 if ( !$this->tableExists( $table ) ) {
1409                         return null;
1410                 }
1411
1412                 $info = $this->indexInfo( $table, $index, $fname );
1413                 if ( is_null( $info ) ) {
1414                         return null;
1415                 } else {
1416                         return $info !== false;
1417                 }
1418         }
1419
1420         public function tableExists( $table, $fname = __METHOD__ ) {
1421                 $tableRaw = $this->tableName( $table, 'raw' );
1422                 if ( isset( $this->mSessionTempTables[$tableRaw] ) ) {
1423                         return true; // already known to exist
1424                 }
1425
1426                 $table = $this->tableName( $table );
1427                 $ignoreErrors = true;
1428                 $res = $this->query( "SELECT 1 FROM $table LIMIT 1", $fname, $ignoreErrors );
1429
1430                 return (bool)$res;
1431         }
1432
1433         public function indexUnique( $table, $index ) {
1434                 $indexInfo = $this->indexInfo( $table, $index );
1435
1436                 if ( !$indexInfo ) {
1437                         return null;
1438                 }
1439
1440                 return !$indexInfo[0]->Non_unique;
1441         }
1442
1443         /**
1444          * Helper for Database::insert().
1445          *
1446          * @param array $options
1447          * @return string
1448          */
1449         protected function makeInsertOptions( $options ) {
1450                 return implode( ' ', $options );
1451         }
1452
1453         public function insert( $table, $a, $fname = __METHOD__, $options = [] ) {
1454                 # No rows to insert, easy just return now
1455                 if ( !count( $a ) ) {
1456                         return true;
1457                 }
1458
1459                 $table = $this->tableName( $table );
1460
1461                 if ( !is_array( $options ) ) {
1462                         $options = [ $options ];
1463                 }
1464
1465                 $fh = null;
1466                 if ( isset( $options['fileHandle'] ) ) {
1467                         $fh = $options['fileHandle'];
1468                 }
1469                 $options = $this->makeInsertOptions( $options );
1470
1471                 if ( isset( $a[0] ) && is_array( $a[0] ) ) {
1472                         $multi = true;
1473                         $keys = array_keys( $a[0] );
1474                 } else {
1475                         $multi = false;
1476                         $keys = array_keys( $a );
1477                 }
1478
1479                 $sql = 'INSERT ' . $options .
1480                         " INTO $table (" . implode( ',', $keys ) . ') VALUES ';
1481
1482                 if ( $multi ) {
1483                         $first = true;
1484                         foreach ( $a as $row ) {
1485                                 if ( $first ) {
1486                                         $first = false;
1487                                 } else {
1488                                         $sql .= ',';
1489                                 }
1490                                 $sql .= '(' . $this->makeList( $row ) . ')';
1491                         }
1492                 } else {
1493                         $sql .= '(' . $this->makeList( $a ) . ')';
1494                 }
1495
1496                 if ( $fh !== null && false === fwrite( $fh, $sql ) ) {
1497                         return false;
1498                 } elseif ( $fh !== null ) {
1499                         return true;
1500                 }
1501
1502                 return (bool)$this->query( $sql, $fname );
1503         }
1504
1505         /**
1506          * Make UPDATE options array for Database::makeUpdateOptions
1507          *
1508          * @param array $options
1509          * @return array
1510          */
1511         protected function makeUpdateOptionsArray( $options ) {
1512                 if ( !is_array( $options ) ) {
1513                         $options = [ $options ];
1514                 }
1515
1516                 $opts = [];
1517
1518                 if ( in_array( 'IGNORE', $options ) ) {
1519                         $opts[] = 'IGNORE';
1520                 }
1521
1522                 return $opts;
1523         }
1524
1525         /**
1526          * Make UPDATE options for the Database::update function
1527          *
1528          * @param array $options The options passed to Database::update
1529          * @return string
1530          */
1531         protected function makeUpdateOptions( $options ) {
1532                 $opts = $this->makeUpdateOptionsArray( $options );
1533
1534                 return implode( ' ', $opts );
1535         }
1536
1537         public function update( $table, $values, $conds, $fname = __METHOD__, $options = [] ) {
1538                 $table = $this->tableName( $table );
1539                 $opts = $this->makeUpdateOptions( $options );
1540                 $sql = "UPDATE $opts $table SET " . $this->makeList( $values, self::LIST_SET );
1541
1542                 if ( $conds !== [] && $conds !== '*' ) {
1543                         $sql .= " WHERE " . $this->makeList( $conds, self::LIST_AND );
1544                 }
1545
1546                 return $this->query( $sql, $fname );
1547         }
1548
1549         public function makeList( $a, $mode = self::LIST_COMMA ) {
1550                 if ( !is_array( $a ) ) {
1551                         throw new DBUnexpectedError( $this, __METHOD__ . ' called with incorrect parameters' );
1552                 }
1553
1554                 $first = true;
1555                 $list = '';
1556
1557                 foreach ( $a as $field => $value ) {
1558                         if ( !$first ) {
1559                                 if ( $mode == self::LIST_AND ) {
1560                                         $list .= ' AND ';
1561                                 } elseif ( $mode == self::LIST_OR ) {
1562                                         $list .= ' OR ';
1563                                 } else {
1564                                         $list .= ',';
1565                                 }
1566                         } else {
1567                                 $first = false;
1568                         }
1569
1570                         if ( ( $mode == self::LIST_AND || $mode == self::LIST_OR ) && is_numeric( $field ) ) {
1571                                 $list .= "($value)";
1572                         } elseif ( $mode == self::LIST_SET && is_numeric( $field ) ) {
1573                                 $list .= "$value";
1574                         } elseif (
1575                                 ( $mode == self::LIST_AND || $mode == self::LIST_OR ) && is_array( $value )
1576                         ) {
1577                                 // Remove null from array to be handled separately if found
1578                                 $includeNull = false;
1579                                 foreach ( array_keys( $value, null, true ) as $nullKey ) {
1580                                         $includeNull = true;
1581                                         unset( $value[$nullKey] );
1582                                 }
1583                                 if ( count( $value ) == 0 && !$includeNull ) {
1584                                         throw new InvalidArgumentException(
1585                                                 __METHOD__ . ": empty input for field $field" );
1586                                 } elseif ( count( $value ) == 0 ) {
1587                                         // only check if $field is null
1588                                         $list .= "$field IS NULL";
1589                                 } else {
1590                                         // IN clause contains at least one valid element
1591                                         if ( $includeNull ) {
1592                                                 // Group subconditions to ensure correct precedence
1593                                                 $list .= '(';
1594                                         }
1595                                         if ( count( $value ) == 1 ) {
1596                                                 // Special-case single values, as IN isn't terribly efficient
1597                                                 // Don't necessarily assume the single key is 0; we don't
1598                                                 // enforce linear numeric ordering on other arrays here.
1599                                                 $value = array_values( $value )[0];
1600                                                 $list .= $field . " = " . $this->addQuotes( $value );
1601                                         } else {
1602                                                 $list .= $field . " IN (" . $this->makeList( $value ) . ") ";
1603                                         }
1604                                         // if null present in array, append IS NULL
1605                                         if ( $includeNull ) {
1606                                                 $list .= " OR $field IS NULL)";
1607                                         }
1608                                 }
1609                         } elseif ( $value === null ) {
1610                                 if ( $mode == self::LIST_AND || $mode == self::LIST_OR ) {
1611                                         $list .= "$field IS ";
1612                                 } elseif ( $mode == self::LIST_SET ) {
1613                                         $list .= "$field = ";
1614                                 }
1615                                 $list .= 'NULL';
1616                         } else {
1617                                 if (
1618                                         $mode == self::LIST_AND || $mode == self::LIST_OR || $mode == self::LIST_SET
1619                                 ) {
1620                                         $list .= "$field = ";
1621                                 }
1622                                 $list .= $mode == self::LIST_NAMES ? $value : $this->addQuotes( $value );
1623                         }
1624                 }
1625
1626                 return $list;
1627         }
1628
1629         public function makeWhereFrom2d( $data, $baseKey, $subKey ) {
1630                 $conds = [];
1631
1632                 foreach ( $data as $base => $sub ) {
1633                         if ( count( $sub ) ) {
1634                                 $conds[] = $this->makeList(
1635                                         [ $baseKey => $base, $subKey => array_keys( $sub ) ],
1636                                         self::LIST_AND );
1637                         }
1638                 }
1639
1640                 if ( $conds ) {
1641                         return $this->makeList( $conds, self::LIST_OR );
1642                 } else {
1643                         // Nothing to search for...
1644                         return false;
1645                 }
1646         }
1647
1648         public function aggregateValue( $valuedata, $valuename = 'value' ) {
1649                 return $valuename;
1650         }
1651
1652         public function bitNot( $field ) {
1653                 return "(~$field)";
1654         }
1655
1656         public function bitAnd( $fieldLeft, $fieldRight ) {
1657                 return "($fieldLeft & $fieldRight)";
1658         }
1659
1660         public function bitOr( $fieldLeft, $fieldRight ) {
1661                 return "($fieldLeft | $fieldRight)";
1662         }
1663
1664         public function buildConcat( $stringList ) {
1665                 return 'CONCAT(' . implode( ',', $stringList ) . ')';
1666         }
1667
1668         public function buildGroupConcatField(
1669                 $delim, $table, $field, $conds = '', $join_conds = []
1670         ) {
1671                 $fld = "GROUP_CONCAT($field SEPARATOR " . $this->addQuotes( $delim ) . ')';
1672
1673                 return '(' . $this->selectSQLText( $table, $fld, $conds, null, [], $join_conds ) . ')';
1674         }
1675
1676         public function buildStringCast( $field ) {
1677                 return $field;
1678         }
1679
1680         public function selectDB( $db ) {
1681                 # Stub. Shouldn't cause serious problems if it's not overridden, but
1682                 # if your database engine supports a concept similar to MySQL's
1683                 # databases you may as well.
1684                 $this->mDBname = $db;
1685
1686                 return true;
1687         }
1688
1689         public function getDBname() {
1690                 return $this->mDBname;
1691         }
1692
1693         public function getServer() {
1694                 return $this->mServer;
1695         }
1696
1697         public function tableName( $name, $format = 'quoted' ) {
1698                 # Skip the entire process when we have a string quoted on both ends.
1699                 # Note that we check the end so that we will still quote any use of
1700                 # use of `database`.table. But won't break things if someone wants
1701                 # to query a database table with a dot in the name.
1702                 if ( $this->isQuotedIdentifier( $name ) ) {
1703                         return $name;
1704                 }
1705
1706                 # Lets test for any bits of text that should never show up in a table
1707                 # name. Basically anything like JOIN or ON which are actually part of
1708                 # SQL queries, but may end up inside of the table value to combine
1709                 # sql. Such as how the API is doing.
1710                 # Note that we use a whitespace test rather than a \b test to avoid
1711                 # any remote case where a word like on may be inside of a table name
1712                 # surrounded by symbols which may be considered word breaks.
1713                 if ( preg_match( '/(^|\s)(DISTINCT|JOIN|ON|AS)(\s|$)/i', $name ) !== 0 ) {
1714                         return $name;
1715                 }
1716
1717                 # Split database and table into proper variables.
1718                 # We reverse the explode so that database.table and table both output
1719                 # the correct table.
1720                 $dbDetails = explode( '.', $name, 3 );
1721                 if ( count( $dbDetails ) == 3 ) {
1722                         list( $database, $schema, $table ) = $dbDetails;
1723                         # We don't want any prefix added in this case
1724                         $prefix = '';
1725                 } elseif ( count( $dbDetails ) == 2 ) {
1726                         list( $database, $table ) = $dbDetails;
1727                         # We don't want any prefix added in this case
1728                         $prefix = '';
1729                         # In dbs that support it, $database may actually be the schema
1730                         # but that doesn't affect any of the functionality here
1731                         $schema = '';
1732                 } else {
1733                         list( $table ) = $dbDetails;
1734                         if ( isset( $this->tableAliases[$table] ) ) {
1735                                 $database = $this->tableAliases[$table]['dbname'];
1736                                 $schema = is_string( $this->tableAliases[$table]['schema'] )
1737                                         ? $this->tableAliases[$table]['schema']
1738                                         : $this->mSchema;
1739                                 $prefix = is_string( $this->tableAliases[$table]['prefix'] )
1740                                         ? $this->tableAliases[$table]['prefix']
1741                                         : $this->mTablePrefix;
1742                         } else {
1743                                 $database = '';
1744                                 $schema = $this->mSchema; # Default schema
1745                                 $prefix = $this->mTablePrefix; # Default prefix
1746                         }
1747                 }
1748
1749                 # Quote $table and apply the prefix if not quoted.
1750                 # $tableName might be empty if this is called from Database::replaceVars()
1751                 $tableName = "{$prefix}{$table}";
1752                 if ( $format === 'quoted'
1753                         && !$this->isQuotedIdentifier( $tableName )
1754                         && $tableName !== ''
1755                 ) {
1756                         $tableName = $this->addIdentifierQuotes( $tableName );
1757                 }
1758
1759                 # Quote $schema and $database and merge them with the table name if needed
1760                 $tableName = $this->prependDatabaseOrSchema( $schema, $tableName, $format );
1761                 $tableName = $this->prependDatabaseOrSchema( $database, $tableName, $format );
1762
1763                 return $tableName;
1764         }
1765
1766         /**
1767          * @param string|null $namespace Database or schema
1768          * @param string $relation Name of table, view, sequence, etc...
1769          * @param string $format One of (raw, quoted)
1770          * @return string Relation name with quoted and merged $namespace as needed
1771          */
1772         private function prependDatabaseOrSchema( $namespace, $relation, $format ) {
1773                 if ( strlen( $namespace ) ) {
1774                         if ( $format === 'quoted' && !$this->isQuotedIdentifier( $namespace ) ) {
1775                                 $namespace = $this->addIdentifierQuotes( $namespace );
1776                         }
1777                         $relation = $namespace . '.' . $relation;
1778                 }
1779
1780                 return $relation;
1781         }
1782
1783         public function tableNames() {
1784                 $inArray = func_get_args();
1785                 $retVal = [];
1786
1787                 foreach ( $inArray as $name ) {
1788                         $retVal[$name] = $this->tableName( $name );
1789                 }
1790
1791                 return $retVal;
1792         }
1793
1794         public function tableNamesN() {
1795                 $inArray = func_get_args();
1796                 $retVal = [];
1797
1798                 foreach ( $inArray as $name ) {
1799                         $retVal[] = $this->tableName( $name );
1800                 }
1801
1802                 return $retVal;
1803         }
1804
1805         /**
1806          * Get an aliased table name
1807          * e.g. tableName AS newTableName
1808          *
1809          * @param string $name Table name, see tableName()
1810          * @param string|bool $alias Alias (optional)
1811          * @return string SQL name for aliased table. Will not alias a table to its own name
1812          */
1813         protected function tableNameWithAlias( $name, $alias = false ) {
1814                 if ( !$alias || $alias == $name ) {
1815                         return $this->tableName( $name );
1816                 } else {
1817                         return $this->tableName( $name ) . ' ' . $this->addIdentifierQuotes( $alias );
1818                 }
1819         }
1820
1821         /**
1822          * Gets an array of aliased table names
1823          *
1824          * @param array $tables [ [alias] => table ]
1825          * @return string[] See tableNameWithAlias()
1826          */
1827         protected function tableNamesWithAlias( $tables ) {
1828                 $retval = [];
1829                 foreach ( $tables as $alias => $table ) {
1830                         if ( is_numeric( $alias ) ) {
1831                                 $alias = $table;
1832                         }
1833                         $retval[] = $this->tableNameWithAlias( $table, $alias );
1834                 }
1835
1836                 return $retval;
1837         }
1838
1839         /**
1840          * Get an aliased field name
1841          * e.g. fieldName AS newFieldName
1842          *
1843          * @param string $name Field name
1844          * @param string|bool $alias Alias (optional)
1845          * @return string SQL name for aliased field. Will not alias a field to its own name
1846          */
1847         protected function fieldNameWithAlias( $name, $alias = false ) {
1848                 if ( !$alias || (string)$alias === (string)$name ) {
1849                         return $name;
1850                 } else {
1851                         return $name . ' AS ' . $this->addIdentifierQuotes( $alias ); // PostgreSQL needs AS
1852                 }
1853         }
1854
1855         /**
1856          * Gets an array of aliased field names
1857          *
1858          * @param array $fields [ [alias] => field ]
1859          * @return string[] See fieldNameWithAlias()
1860          */
1861         protected function fieldNamesWithAlias( $fields ) {
1862                 $retval = [];
1863                 foreach ( $fields as $alias => $field ) {
1864                         if ( is_numeric( $alias ) ) {
1865                                 $alias = $field;
1866                         }
1867                         $retval[] = $this->fieldNameWithAlias( $field, $alias );
1868                 }
1869
1870                 return $retval;
1871         }
1872
1873         /**
1874          * Get the aliased table name clause for a FROM clause
1875          * which might have a JOIN and/or USE INDEX or IGNORE INDEX clause
1876          *
1877          * @param array $tables ( [alias] => table )
1878          * @param array $use_index Same as for select()
1879          * @param array $ignore_index Same as for select()
1880          * @param array $join_conds Same as for select()
1881          * @return string
1882          */
1883         protected function tableNamesWithIndexClauseOrJOIN(
1884                 $tables, $use_index = [], $ignore_index = [], $join_conds = []
1885         ) {
1886                 $ret = [];
1887                 $retJOIN = [];
1888                 $use_index = (array)$use_index;
1889                 $ignore_index = (array)$ignore_index;
1890                 $join_conds = (array)$join_conds;
1891
1892                 foreach ( $tables as $alias => $table ) {
1893                         if ( !is_string( $alias ) ) {
1894                                 // No alias? Set it equal to the table name
1895                                 $alias = $table;
1896                         }
1897                         // Is there a JOIN clause for this table?
1898                         if ( isset( $join_conds[$alias] ) ) {
1899                                 list( $joinType, $conds ) = $join_conds[$alias];
1900                                 $tableClause = $joinType;
1901                                 $tableClause .= ' ' . $this->tableNameWithAlias( $table, $alias );
1902                                 if ( isset( $use_index[$alias] ) ) { // has USE INDEX?
1903                                         $use = $this->useIndexClause( implode( ',', (array)$use_index[$alias] ) );
1904                                         if ( $use != '' ) {
1905                                                 $tableClause .= ' ' . $use;
1906                                         }
1907                                 }
1908                                 if ( isset( $ignore_index[$alias] ) ) { // has IGNORE INDEX?
1909                                         $ignore = $this->ignoreIndexClause(
1910                                                 implode( ',', (array)$ignore_index[$alias] ) );
1911                                         if ( $ignore != '' ) {
1912                                                 $tableClause .= ' ' . $ignore;
1913                                         }
1914                                 }
1915                                 $on = $this->makeList( (array)$conds, self::LIST_AND );
1916                                 if ( $on != '' ) {
1917                                         $tableClause .= ' ON (' . $on . ')';
1918                                 }
1919
1920                                 $retJOIN[] = $tableClause;
1921                         } elseif ( isset( $use_index[$alias] ) ) {
1922                                 // Is there an INDEX clause for this table?
1923                                 $tableClause = $this->tableNameWithAlias( $table, $alias );
1924                                 $tableClause .= ' ' . $this->useIndexClause(
1925                                                 implode( ',', (array)$use_index[$alias] )
1926                                         );
1927
1928                                 $ret[] = $tableClause;
1929                         } elseif ( isset( $ignore_index[$alias] ) ) {
1930                                 // Is there an INDEX clause for this table?
1931                                 $tableClause = $this->tableNameWithAlias( $table, $alias );
1932                                 $tableClause .= ' ' . $this->ignoreIndexClause(
1933                                                 implode( ',', (array)$ignore_index[$alias] )
1934                                         );
1935
1936                                 $ret[] = $tableClause;
1937                         } else {
1938                                 $tableClause = $this->tableNameWithAlias( $table, $alias );
1939
1940                                 $ret[] = $tableClause;
1941                         }
1942                 }
1943
1944                 // We can't separate explicit JOIN clauses with ',', use ' ' for those
1945                 $implicitJoins = !empty( $ret ) ? implode( ',', $ret ) : "";
1946                 $explicitJoins = !empty( $retJOIN ) ? implode( ' ', $retJOIN ) : "";
1947
1948                 // Compile our final table clause
1949                 return implode( ' ', [ $implicitJoins, $explicitJoins ] );
1950         }
1951
1952         /**
1953          * Get the name of an index in a given table.
1954          *
1955          * @param string $index
1956          * @return string
1957          */
1958         protected function indexName( $index ) {
1959                 return $index;
1960         }
1961
1962         public function addQuotes( $s ) {
1963                 if ( $s instanceof Blob ) {
1964                         $s = $s->fetch();
1965                 }
1966                 if ( $s === null ) {
1967                         return 'NULL';
1968                 } elseif ( is_bool( $s ) ) {
1969                         return (int)$s;
1970                 } else {
1971                         # This will also quote numeric values. This should be harmless,
1972                         # and protects against weird problems that occur when they really
1973                         # _are_ strings such as article titles and string->number->string
1974                         # conversion is not 1:1.
1975                         return "'" . $this->strencode( $s ) . "'";
1976                 }
1977         }
1978
1979         /**
1980          * Quotes an identifier using `backticks` or "double quotes" depending on the database type.
1981          * MySQL uses `backticks` while basically everything else uses double quotes.
1982          * Since MySQL is the odd one out here the double quotes are our generic
1983          * and we implement backticks in DatabaseMysql.
1984          *
1985          * @param string $s
1986          * @return string
1987          */
1988         public function addIdentifierQuotes( $s ) {
1989                 return '"' . str_replace( '"', '""', $s ) . '"';
1990         }
1991
1992         /**
1993          * Returns if the given identifier looks quoted or not according to
1994          * the database convention for quoting identifiers .
1995          *
1996          * @note Do not use this to determine if untrusted input is safe.
1997          *   A malicious user can trick this function.
1998          * @param string $name
1999          * @return bool
2000          */
2001         public function isQuotedIdentifier( $name ) {
2002                 return $name[0] == '"' && substr( $name, -1, 1 ) == '"';
2003         }
2004
2005         /**
2006          * @param string $s
2007          * @return string
2008          */
2009         protected function escapeLikeInternal( $s ) {
2010                 return addcslashes( $s, '\%_' );
2011         }
2012
2013         public function buildLike() {
2014                 $params = func_get_args();
2015
2016                 if ( count( $params ) > 0 && is_array( $params[0] ) ) {
2017                         $params = $params[0];
2018                 }
2019
2020                 $s = '';
2021
2022                 foreach ( $params as $value ) {
2023                         if ( $value instanceof LikeMatch ) {
2024                                 $s .= $value->toString();
2025                         } else {
2026                                 $s .= $this->escapeLikeInternal( $value );
2027                         }
2028                 }
2029
2030                 return " LIKE {$this->addQuotes( $s )} ";
2031         }
2032
2033         public function anyChar() {
2034                 return new LikeMatch( '_' );
2035         }
2036
2037         public function anyString() {
2038                 return new LikeMatch( '%' );
2039         }
2040
2041         public function nextSequenceValue( $seqName ) {
2042                 return null;
2043         }
2044
2045         /**
2046          * USE INDEX clause. Unlikely to be useful for anything but MySQL. This
2047          * is only needed because a) MySQL must be as efficient as possible due to
2048          * its use on Wikipedia, and b) MySQL 4.0 is kind of dumb sometimes about
2049          * which index to pick. Anyway, other databases might have different
2050          * indexes on a given table. So don't bother overriding this unless you're
2051          * MySQL.
2052          * @param string $index
2053          * @return string
2054          */
2055         public function useIndexClause( $index ) {
2056                 return '';
2057         }
2058
2059         /**
2060          * IGNORE INDEX clause. Unlikely to be useful for anything but MySQL. This
2061          * is only needed because a) MySQL must be as efficient as possible due to
2062          * its use on Wikipedia, and b) MySQL 4.0 is kind of dumb sometimes about
2063          * which index to pick. Anyway, other databases might have different
2064          * indexes on a given table. So don't bother overriding this unless you're
2065          * MySQL.
2066          * @param string $index
2067          * @return string
2068          */
2069         public function ignoreIndexClause( $index ) {
2070                 return '';
2071         }
2072
2073         public function replace( $table, $uniqueIndexes, $rows, $fname = __METHOD__ ) {
2074                 $quotedTable = $this->tableName( $table );
2075
2076                 if ( count( $rows ) == 0 ) {
2077                         return;
2078                 }
2079
2080                 # Single row case
2081                 if ( !is_array( reset( $rows ) ) ) {
2082                         $rows = [ $rows ];
2083                 }
2084
2085                 // @FXIME: this is not atomic, but a trx would break affectedRows()
2086                 foreach ( $rows as $row ) {
2087                         # Delete rows which collide
2088                         if ( $uniqueIndexes ) {
2089                                 $sql = "DELETE FROM $quotedTable WHERE ";
2090                                 $first = true;
2091                                 foreach ( $uniqueIndexes as $index ) {
2092                                         if ( $first ) {
2093                                                 $first = false;
2094                                                 $sql .= '( ';
2095                                         } else {
2096                                                 $sql .= ' ) OR ( ';
2097                                         }
2098                                         if ( is_array( $index ) ) {
2099                                                 $first2 = true;
2100                                                 foreach ( $index as $col ) {
2101                                                         if ( $first2 ) {
2102                                                                 $first2 = false;
2103                                                         } else {
2104                                                                 $sql .= ' AND ';
2105                                                         }
2106                                                         $sql .= $col . '=' . $this->addQuotes( $row[$col] );
2107                                                 }
2108                                         } else {
2109                                                 $sql .= $index . '=' . $this->addQuotes( $row[$index] );
2110                                         }
2111                                 }
2112                                 $sql .= ' )';
2113                                 $this->query( $sql, $fname );
2114                         }
2115
2116                         # Now insert the row
2117                         $this->insert( $table, $row, $fname );
2118                 }
2119         }
2120
2121         /**
2122          * REPLACE query wrapper for MySQL and SQLite, which have a native REPLACE
2123          * statement.
2124          *
2125          * @param string $table Table name
2126          * @param array|string $rows Row(s) to insert
2127          * @param string $fname Caller function name
2128          *
2129          * @return ResultWrapper
2130          */
2131         protected function nativeReplace( $table, $rows, $fname ) {
2132                 $table = $this->tableName( $table );
2133
2134                 # Single row case
2135                 if ( !is_array( reset( $rows ) ) ) {
2136                         $rows = [ $rows ];
2137                 }
2138
2139                 $sql = "REPLACE INTO $table (" . implode( ',', array_keys( $rows[0] ) ) . ') VALUES ';
2140                 $first = true;
2141
2142                 foreach ( $rows as $row ) {
2143                         if ( $first ) {
2144                                 $first = false;
2145                         } else {
2146                                 $sql .= ',';
2147                         }
2148
2149                         $sql .= '(' . $this->makeList( $row ) . ')';
2150                 }
2151
2152                 return $this->query( $sql, $fname );
2153         }
2154
2155         public function upsert( $table, array $rows, array $uniqueIndexes, array $set,
2156                 $fname = __METHOD__
2157         ) {
2158                 if ( !count( $rows ) ) {
2159                         return true; // nothing to do
2160                 }
2161
2162                 if ( !is_array( reset( $rows ) ) ) {
2163                         $rows = [ $rows ];
2164                 }
2165
2166                 if ( count( $uniqueIndexes ) ) {
2167                         $clauses = []; // list WHERE clauses that each identify a single row
2168                         foreach ( $rows as $row ) {
2169                                 foreach ( $uniqueIndexes as $index ) {
2170                                         $index = is_array( $index ) ? $index : [ $index ]; // columns
2171                                         $rowKey = []; // unique key to this row
2172                                         foreach ( $index as $column ) {
2173                                                 $rowKey[$column] = $row[$column];
2174                                         }
2175                                         $clauses[] = $this->makeList( $rowKey, self::LIST_AND );
2176                                 }
2177                         }
2178                         $where = [ $this->makeList( $clauses, self::LIST_OR ) ];
2179                 } else {
2180                         $where = false;
2181                 }
2182
2183                 $useTrx = !$this->mTrxLevel;
2184                 if ( $useTrx ) {
2185                         $this->begin( $fname, self::TRANSACTION_INTERNAL );
2186                 }
2187                 try {
2188                         # Update any existing conflicting row(s)
2189                         if ( $where !== false ) {
2190                                 $ok = $this->update( $table, $set, $where, $fname );
2191                         } else {
2192                                 $ok = true;
2193                         }
2194                         # Now insert any non-conflicting row(s)
2195                         $ok = $this->insert( $table, $rows, $fname, [ 'IGNORE' ] ) && $ok;
2196                 } catch ( Exception $e ) {
2197                         if ( $useTrx ) {
2198                                 $this->rollback( $fname, self::FLUSHING_INTERNAL );
2199                         }
2200                         throw $e;
2201                 }
2202                 if ( $useTrx ) {
2203                         $this->commit( $fname, self::FLUSHING_INTERNAL );
2204                 }
2205
2206                 return $ok;
2207         }
2208
2209         public function deleteJoin( $delTable, $joinTable, $delVar, $joinVar, $conds,
2210                 $fname = __METHOD__
2211         ) {
2212                 if ( !$conds ) {
2213                         throw new DBUnexpectedError( $this, __METHOD__ . ' called with empty $conds' );
2214                 }
2215
2216                 $delTable = $this->tableName( $delTable );
2217                 $joinTable = $this->tableName( $joinTable );
2218                 $sql = "DELETE FROM $delTable WHERE $delVar IN (SELECT $joinVar FROM $joinTable ";
2219                 if ( $conds != '*' ) {
2220                         $sql .= 'WHERE ' . $this->makeList( $conds, self::LIST_AND );
2221                 }
2222                 $sql .= ')';
2223
2224                 $this->query( $sql, $fname );
2225         }
2226
2227         public function textFieldSize( $table, $field ) {
2228                 $table = $this->tableName( $table );
2229                 $sql = "SHOW COLUMNS FROM $table LIKE \"$field\";";
2230                 $res = $this->query( $sql, __METHOD__ );
2231                 $row = $this->fetchObject( $res );
2232
2233                 $m = [];
2234
2235                 if ( preg_match( '/\((.*)\)/', $row->Type, $m ) ) {
2236                         $size = $m[1];
2237                 } else {
2238                         $size = -1;
2239                 }
2240
2241                 return $size;
2242         }
2243
2244         public function delete( $table, $conds, $fname = __METHOD__ ) {
2245                 if ( !$conds ) {
2246                         throw new DBUnexpectedError( $this, __METHOD__ . ' called with no conditions' );
2247                 }
2248
2249                 $table = $this->tableName( $table );
2250                 $sql = "DELETE FROM $table";
2251
2252                 if ( $conds != '*' ) {
2253                         if ( is_array( $conds ) ) {
2254                                 $conds = $this->makeList( $conds, self::LIST_AND );
2255                         }
2256                         $sql .= ' WHERE ' . $conds;
2257                 }
2258
2259                 return $this->query( $sql, $fname );
2260         }
2261
2262         public function insertSelect(
2263                 $destTable, $srcTable, $varMap, $conds,
2264                 $fname = __METHOD__, $insertOptions = [], $selectOptions = []
2265         ) {
2266                 if ( $this->cliMode ) {
2267                         // For massive migrations with downtime, we don't want to select everything
2268                         // into memory and OOM, so do all this native on the server side if possible.
2269                         return $this->nativeInsertSelect(
2270                                 $destTable,
2271                                 $srcTable,
2272                                 $varMap,
2273                                 $conds,
2274                                 $fname,
2275                                 $insertOptions,
2276                                 $selectOptions
2277                         );
2278                 }
2279
2280                 // For web requests, do a locking SELECT and then INSERT. This puts the SELECT burden
2281                 // on only the master (without needing row-based-replication). It also makes it easy to
2282                 // know how big the INSERT is going to be.
2283                 $fields = [];
2284                 foreach ( $varMap as $dstColumn => $sourceColumnOrSql ) {
2285                         $fields[] = $this->fieldNameWithAlias( $sourceColumnOrSql, $dstColumn );
2286                 }
2287                 $selectOptions[] = 'FOR UPDATE';
2288                 $res = $this->select( $srcTable, implode( ',', $fields ), $conds, $fname, $selectOptions );
2289                 if ( !$res ) {
2290                         return false;
2291                 }
2292
2293                 $rows = [];
2294                 foreach ( $res as $row ) {
2295                         $rows[] = (array)$row;
2296                 }
2297
2298                 return $this->insert( $destTable, $rows, $fname, $insertOptions );
2299         }
2300
2301         protected function nativeInsertSelect( $destTable, $srcTable, $varMap, $conds,
2302                 $fname = __METHOD__,
2303                 $insertOptions = [], $selectOptions = []
2304         ) {
2305                 $destTable = $this->tableName( $destTable );
2306
2307                 if ( !is_array( $insertOptions ) ) {
2308                         $insertOptions = [ $insertOptions ];
2309                 }
2310
2311                 $insertOptions = $this->makeInsertOptions( $insertOptions );
2312
2313                 if ( !is_array( $selectOptions ) ) {
2314                         $selectOptions = [ $selectOptions ];
2315                 }
2316
2317                 list( $startOpts, $useIndex, $tailOpts, $ignoreIndex ) = $this->makeSelectOptions(
2318                         $selectOptions );
2319
2320                 if ( is_array( $srcTable ) ) {
2321                         $srcTable = implode( ',', array_map( [ $this, 'tableName' ], $srcTable ) );
2322                 } else {
2323                         $srcTable = $this->tableName( $srcTable );
2324                 }
2325
2326                 $sql = "INSERT $insertOptions" .
2327                         " INTO $destTable (" . implode( ',', array_keys( $varMap ) ) . ')' .
2328                         " SELECT $startOpts " . implode( ',', $varMap ) .
2329                         " FROM $srcTable $useIndex $ignoreIndex ";
2330
2331                 if ( $conds != '*' ) {
2332                         if ( is_array( $conds ) ) {
2333                                 $conds = $this->makeList( $conds, self::LIST_AND );
2334                         }
2335                         $sql .= " WHERE $conds";
2336                 }
2337
2338                 $sql .= " $tailOpts";
2339
2340                 return $this->query( $sql, $fname );
2341         }
2342
2343         /**
2344          * Construct a LIMIT query with optional offset. This is used for query
2345          * pages. The SQL should be adjusted so that only the first $limit rows
2346          * are returned. If $offset is provided as well, then the first $offset
2347          * rows should be discarded, and the next $limit rows should be returned.
2348          * If the result of the query is not ordered, then the rows to be returned
2349          * are theoretically arbitrary.
2350          *
2351          * $sql is expected to be a SELECT, if that makes a difference.
2352          *
2353          * The version provided by default works in MySQL and SQLite. It will very
2354          * likely need to be overridden for most other DBMSes.
2355          *
2356          * @param string $sql SQL query we will append the limit too
2357          * @param int $limit The SQL limit
2358          * @param int|bool $offset The SQL offset (default false)
2359          * @throws DBUnexpectedError
2360          * @return string
2361          */
2362         public function limitResult( $sql, $limit, $offset = false ) {
2363                 if ( !is_numeric( $limit ) ) {
2364                         throw new DBUnexpectedError( $this,
2365                                 "Invalid non-numeric limit passed to limitResult()\n" );
2366                 }
2367
2368                 return "$sql LIMIT "
2369                 . ( ( is_numeric( $offset ) && $offset != 0 ) ? "{$offset}," : "" )
2370                 . "{$limit} ";
2371         }
2372
2373         public function unionSupportsOrderAndLimit() {
2374                 return true; // True for almost every DB supported
2375         }
2376
2377         public function unionQueries( $sqls, $all ) {
2378                 $glue = $all ? ') UNION ALL (' : ') UNION (';
2379
2380                 return '(' . implode( $glue, $sqls ) . ')';
2381         }
2382
2383         public function conditional( $cond, $trueVal, $falseVal ) {
2384                 if ( is_array( $cond ) ) {
2385                         $cond = $this->makeList( $cond, self::LIST_AND );
2386                 }
2387
2388                 return " (CASE WHEN $cond THEN $trueVal ELSE $falseVal END) ";
2389         }
2390
2391         public function strreplace( $orig, $old, $new ) {
2392                 return "REPLACE({$orig}, {$old}, {$new})";
2393         }
2394
2395         public function getServerUptime() {
2396                 return 0;
2397         }
2398
2399         public function wasDeadlock() {
2400                 return false;
2401         }
2402
2403         public function wasLockTimeout() {
2404                 return false;
2405         }
2406
2407         public function wasErrorReissuable() {
2408                 return false;
2409         }
2410
2411         public function wasReadOnlyError() {
2412                 return false;
2413         }
2414
2415         /**
2416          * Do not use this method outside of Database/DBError classes
2417          *
2418          * @param integer|string $errno
2419          * @return bool Whether the given query error was a connection drop
2420          */
2421         public function wasConnectionError( $errno ) {
2422                 return false;
2423         }
2424
2425         public function deadlockLoop() {
2426                 $args = func_get_args();
2427                 $function = array_shift( $args );
2428                 $tries = self::DEADLOCK_TRIES;
2429
2430                 $this->begin( __METHOD__ );
2431
2432                 $retVal = null;
2433                 /** @var Exception $e */
2434                 $e = null;
2435                 do {
2436                         try {
2437                                 $retVal = call_user_func_array( $function, $args );
2438                                 break;
2439                         } catch ( DBQueryError $e ) {
2440                                 if ( $this->wasDeadlock() ) {
2441                                         // Retry after a randomized delay
2442                                         usleep( mt_rand( self::DEADLOCK_DELAY_MIN, self::DEADLOCK_DELAY_MAX ) );
2443                                 } else {
2444                                         // Throw the error back up
2445                                         throw $e;
2446                                 }
2447                         }
2448                 } while ( --$tries > 0 );
2449
2450                 if ( $tries <= 0 ) {
2451                         // Too many deadlocks; give up
2452                         $this->rollback( __METHOD__ );
2453                         throw $e;
2454                 } else {
2455                         $this->commit( __METHOD__ );
2456
2457                         return $retVal;
2458                 }
2459         }
2460
2461         public function masterPosWait( DBMasterPos $pos, $timeout ) {
2462                 # Real waits are implemented in the subclass.
2463                 return 0;
2464         }
2465
2466         public function getReplicaPos() {
2467                 # Stub
2468                 return false;
2469         }
2470
2471         public function getMasterPos() {
2472                 # Stub
2473                 return false;
2474         }
2475
2476         public function serverIsReadOnly() {
2477                 return false;
2478         }
2479
2480         final public function onTransactionResolution( callable $callback, $fname = __METHOD__ ) {
2481                 if ( !$this->mTrxLevel ) {
2482                         throw new DBUnexpectedError( $this, "No transaction is active." );
2483                 }
2484                 $this->mTrxEndCallbacks[] = [ $callback, $fname ];
2485         }
2486
2487         final public function onTransactionIdle( callable $callback, $fname = __METHOD__ ) {
2488                 $this->mTrxIdleCallbacks[] = [ $callback, $fname ];
2489                 if ( !$this->mTrxLevel ) {
2490                         $this->runOnTransactionIdleCallbacks( self::TRIGGER_IDLE );
2491                 }
2492         }
2493
2494         final public function onTransactionPreCommitOrIdle( callable $callback, $fname = __METHOD__ ) {
2495                 if ( $this->mTrxLevel ) {
2496                         $this->mTrxPreCommitCallbacks[] = [ $callback, $fname ];
2497                 } else {
2498                         // If no transaction is active, then make one for this callback
2499                         $this->startAtomic( __METHOD__ );
2500                         try {
2501                                 call_user_func( $callback );
2502                                 $this->endAtomic( __METHOD__ );
2503                         } catch ( Exception $e ) {
2504                                 $this->rollback( __METHOD__, self::FLUSHING_INTERNAL );
2505                                 throw $e;
2506                         }
2507                 }
2508         }
2509
2510         final public function setTransactionListener( $name, callable $callback = null ) {
2511                 if ( $callback ) {
2512                         $this->mTrxRecurringCallbacks[$name] = $callback;
2513                 } else {
2514                         unset( $this->mTrxRecurringCallbacks[$name] );
2515                 }
2516         }
2517
2518         /**
2519          * Whether to disable running of post-COMMIT/ROLLBACK callbacks
2520          *
2521          * This method should not be used outside of Database/LoadBalancer
2522          *
2523          * @param bool $suppress
2524          * @since 1.28
2525          */
2526         final public function setTrxEndCallbackSuppression( $suppress ) {
2527                 $this->mTrxEndCallbacksSuppressed = $suppress;
2528         }
2529
2530         /**
2531          * Actually run and consume any "on transaction idle/resolution" callbacks.
2532          *
2533          * This method should not be used outside of Database/LoadBalancer
2534          *
2535          * @param integer $trigger IDatabase::TRIGGER_* constant
2536          * @since 1.20
2537          * @throws Exception
2538          */
2539         public function runOnTransactionIdleCallbacks( $trigger ) {
2540                 if ( $this->mTrxEndCallbacksSuppressed ) {
2541                         return;
2542                 }
2543
2544                 $autoTrx = $this->getFlag( self::DBO_TRX ); // automatic begin() enabled?
2545                 /** @var Exception $e */
2546                 $e = null; // first exception
2547                 do { // callbacks may add callbacks :)
2548                         $callbacks = array_merge(
2549                                 $this->mTrxIdleCallbacks,
2550                                 $this->mTrxEndCallbacks // include "transaction resolution" callbacks
2551                         );
2552                         $this->mTrxIdleCallbacks = []; // consumed (and recursion guard)
2553                         $this->mTrxEndCallbacks = []; // consumed (recursion guard)
2554                         foreach ( $callbacks as $callback ) {
2555                                 try {
2556                                         list( $phpCallback ) = $callback;
2557                                         $this->clearFlag( self::DBO_TRX ); // make each query its own transaction
2558                                         call_user_func_array( $phpCallback, [ $trigger ] );
2559                                         if ( $autoTrx ) {
2560                                                 $this->setFlag( self::DBO_TRX ); // restore automatic begin()
2561                                         } else {
2562                                                 $this->clearFlag( self::DBO_TRX ); // restore auto-commit
2563                                         }
2564                                 } catch ( Exception $ex ) {
2565                                         call_user_func( $this->errorLogger, $ex );
2566                                         $e = $e ?: $ex;
2567                                         // Some callbacks may use startAtomic/endAtomic, so make sure
2568                                         // their transactions are ended so other callbacks don't fail
2569                                         if ( $this->trxLevel() ) {
2570                                                 $this->rollback( __METHOD__, self::FLUSHING_INTERNAL );
2571                                         }
2572                                 }
2573                         }
2574                 } while ( count( $this->mTrxIdleCallbacks ) );
2575
2576                 if ( $e instanceof Exception ) {
2577                         throw $e; // re-throw any first exception
2578                 }
2579         }
2580
2581         /**
2582          * Actually run and consume any "on transaction pre-commit" callbacks.
2583          *
2584          * This method should not be used outside of Database/LoadBalancer
2585          *
2586          * @since 1.22
2587          * @throws Exception
2588          */
2589         public function runOnTransactionPreCommitCallbacks() {
2590                 $e = null; // first exception
2591                 do { // callbacks may add callbacks :)
2592                         $callbacks = $this->mTrxPreCommitCallbacks;
2593                         $this->mTrxPreCommitCallbacks = []; // consumed (and recursion guard)
2594                         foreach ( $callbacks as $callback ) {
2595                                 try {
2596                                         list( $phpCallback ) = $callback;
2597                                         call_user_func( $phpCallback );
2598                                 } catch ( Exception $ex ) {
2599                                         call_user_func( $this->errorLogger, $ex );
2600                                         $e = $e ?: $ex;
2601                                 }
2602                         }
2603                 } while ( count( $this->mTrxPreCommitCallbacks ) );
2604
2605                 if ( $e instanceof Exception ) {
2606                         throw $e; // re-throw any first exception
2607                 }
2608         }
2609
2610         /**
2611          * Actually run any "transaction listener" callbacks.
2612          *
2613          * This method should not be used outside of Database/LoadBalancer
2614          *
2615          * @param integer $trigger IDatabase::TRIGGER_* constant
2616          * @throws Exception
2617          * @since 1.20
2618          */
2619         public function runTransactionListenerCallbacks( $trigger ) {
2620                 if ( $this->mTrxEndCallbacksSuppressed ) {
2621                         return;
2622                 }
2623
2624                 /** @var Exception $e */
2625                 $e = null; // first exception
2626
2627                 foreach ( $this->mTrxRecurringCallbacks as $phpCallback ) {
2628                         try {
2629                                 $phpCallback( $trigger, $this );
2630                         } catch ( Exception $ex ) {
2631                                 call_user_func( $this->errorLogger, $ex );
2632                                 $e = $e ?: $ex;
2633                         }
2634                 }
2635
2636                 if ( $e instanceof Exception ) {
2637                         throw $e; // re-throw any first exception
2638                 }
2639         }
2640
2641         final public function startAtomic( $fname = __METHOD__ ) {
2642                 if ( !$this->mTrxLevel ) {
2643                         $this->begin( $fname, self::TRANSACTION_INTERNAL );
2644                         // If DBO_TRX is set, a series of startAtomic/endAtomic pairs will result
2645                         // in all changes being in one transaction to keep requests transactional.
2646                         if ( !$this->getFlag( self::DBO_TRX ) ) {
2647                                 $this->mTrxAutomaticAtomic = true;
2648                         }
2649                 }
2650
2651                 $this->mTrxAtomicLevels[] = $fname;
2652         }
2653
2654         final public function endAtomic( $fname = __METHOD__ ) {
2655                 if ( !$this->mTrxLevel ) {
2656                         throw new DBUnexpectedError( $this, "No atomic transaction is open (got $fname)." );
2657                 }
2658                 if ( !$this->mTrxAtomicLevels ||
2659                         array_pop( $this->mTrxAtomicLevels ) !== $fname
2660                 ) {
2661                         throw new DBUnexpectedError( $this, "Invalid atomic section ended (got $fname)." );
2662                 }
2663
2664                 if ( !$this->mTrxAtomicLevels && $this->mTrxAutomaticAtomic ) {
2665                         $this->commit( $fname, self::FLUSHING_INTERNAL );
2666                 }
2667         }
2668
2669         final public function doAtomicSection( $fname, callable $callback ) {
2670                 $this->startAtomic( $fname );
2671                 try {
2672                         $res = call_user_func_array( $callback, [ $this, $fname ] );
2673                 } catch ( Exception $e ) {
2674                         $this->rollback( $fname, self::FLUSHING_INTERNAL );
2675                         throw $e;
2676                 }
2677                 $this->endAtomic( $fname );
2678
2679                 return $res;
2680         }
2681
2682         final public function begin( $fname = __METHOD__, $mode = self::TRANSACTION_EXPLICIT ) {
2683                 // Protect against mismatched atomic section, transaction nesting, and snapshot loss
2684                 if ( $this->mTrxLevel ) {
2685                         if ( $this->mTrxAtomicLevels ) {
2686                                 $levels = implode( ', ', $this->mTrxAtomicLevels );
2687                                 $msg = "$fname: Got explicit BEGIN while atomic section(s) $levels are open.";
2688                                 throw new DBUnexpectedError( $this, $msg );
2689                         } elseif ( !$this->mTrxAutomatic ) {
2690                                 $msg = "$fname: Explicit transaction already active (from {$this->mTrxFname}).";
2691                                 throw new DBUnexpectedError( $this, $msg );
2692                         } else {
2693                                 // @TODO: make this an exception at some point
2694                                 $msg = "$fname: Implicit transaction already active (from {$this->mTrxFname}).";
2695                                 $this->queryLogger->error( $msg );
2696                                 return; // join the main transaction set
2697                         }
2698                 } elseif ( $this->getFlag( self::DBO_TRX ) && $mode !== self::TRANSACTION_INTERNAL ) {
2699                         // @TODO: make this an exception at some point
2700                         $msg = "$fname: Implicit transaction expected (DBO_TRX set).";
2701                         $this->queryLogger->error( $msg );
2702                         return; // let any writes be in the main transaction
2703                 }
2704
2705                 // Avoid fatals if close() was called
2706                 $this->assertOpen();
2707
2708                 $this->doBegin( $fname );
2709                 $this->mTrxTimestamp = microtime( true );
2710                 $this->mTrxFname = $fname;
2711                 $this->mTrxDoneWrites = false;
2712                 $this->mTrxAutomaticAtomic = false;
2713                 $this->mTrxAtomicLevels = [];
2714                 $this->mTrxShortId = sprintf( '%06x', mt_rand( 0, 0xffffff ) );
2715                 $this->mTrxWriteDuration = 0.0;
2716                 $this->mTrxWriteQueryCount = 0;
2717                 $this->mTrxWriteAdjDuration = 0.0;
2718                 $this->mTrxWriteAdjQueryCount = 0;
2719                 $this->mTrxWriteCallers = [];
2720                 // First SELECT after BEGIN will establish the snapshot in REPEATABLE-READ.
2721                 // Get an estimate of the replica DB lag before then, treating estimate staleness
2722                 // as lag itself just to be safe
2723                 $status = $this->getApproximateLagStatus();
2724                 $this->mTrxReplicaLag = $status['lag'] + ( microtime( true ) - $status['since'] );
2725                 // T147697: make explicitTrxActive() return true until begin() finishes. This way, no
2726                 // caller will think its OK to muck around with the transaction just because startAtomic()
2727                 // has not yet completed (e.g. setting mTrxAtomicLevels).
2728                 $this->mTrxAutomatic = ( $mode === self::TRANSACTION_INTERNAL );
2729         }
2730
2731         /**
2732          * Issues the BEGIN command to the database server.
2733          *
2734          * @see Database::begin()
2735          * @param string $fname
2736          */
2737         protected function doBegin( $fname ) {
2738                 $this->query( 'BEGIN', $fname );
2739                 $this->mTrxLevel = 1;
2740         }
2741
2742         final public function commit( $fname = __METHOD__, $flush = '' ) {
2743                 if ( $this->mTrxLevel && $this->mTrxAtomicLevels ) {
2744                         // There are still atomic sections open. This cannot be ignored
2745                         $levels = implode( ', ', $this->mTrxAtomicLevels );
2746                         throw new DBUnexpectedError(
2747                                 $this,
2748                                 "$fname: Got COMMIT while atomic sections $levels are still open."
2749                         );
2750                 }
2751
2752                 if ( $flush === self::FLUSHING_INTERNAL || $flush === self::FLUSHING_ALL_PEERS ) {
2753                         if ( !$this->mTrxLevel ) {
2754                                 return; // nothing to do
2755                         } elseif ( !$this->mTrxAutomatic ) {
2756                                 throw new DBUnexpectedError(
2757                                         $this,
2758                                         "$fname: Flushing an explicit transaction, getting out of sync."
2759                                 );
2760                         }
2761                 } else {
2762                         if ( !$this->mTrxLevel ) {
2763                                 $this->queryLogger->error(
2764                                         "$fname: No transaction to commit, something got out of sync." );
2765                                 return; // nothing to do
2766                         } elseif ( $this->mTrxAutomatic ) {
2767                                 // @TODO: make this an exception at some point
2768                                 $msg = "$fname: Explicit commit of implicit transaction.";
2769                                 $this->queryLogger->error( $msg );
2770                                 return; // wait for the main transaction set commit round
2771                         }
2772                 }
2773
2774                 // Avoid fatals if close() was called
2775                 $this->assertOpen();
2776
2777                 $this->runOnTransactionPreCommitCallbacks();
2778                 $writeTime = $this->pendingWriteQueryDuration( self::ESTIMATE_DB_APPLY );
2779                 $this->doCommit( $fname );
2780                 if ( $this->mTrxDoneWrites ) {
2781                         $this->mLastWriteTime = microtime( true );
2782                         $this->trxProfiler->transactionWritingOut(
2783                                 $this->mServer, $this->mDBname, $this->mTrxShortId, $writeTime );
2784                 }
2785
2786                 $this->runOnTransactionIdleCallbacks( self::TRIGGER_COMMIT );
2787                 $this->runTransactionListenerCallbacks( self::TRIGGER_COMMIT );
2788         }
2789
2790         /**
2791          * Issues the COMMIT command to the database server.
2792          *
2793          * @see Database::commit()
2794          * @param string $fname
2795          */
2796         protected function doCommit( $fname ) {
2797                 if ( $this->mTrxLevel ) {
2798                         $this->query( 'COMMIT', $fname );
2799                         $this->mTrxLevel = 0;
2800                 }
2801         }
2802
2803         final public function rollback( $fname = __METHOD__, $flush = '' ) {
2804                 if ( $flush === self::FLUSHING_INTERNAL || $flush === self::FLUSHING_ALL_PEERS ) {
2805                         if ( !$this->mTrxLevel ) {
2806                                 return; // nothing to do
2807                         }
2808                 } else {
2809                         if ( !$this->mTrxLevel ) {
2810                                 $this->queryLogger->error(
2811                                         "$fname: No transaction to rollback, something got out of sync." );
2812                                 return; // nothing to do
2813                         } elseif ( $this->getFlag( self::DBO_TRX ) ) {
2814                                 throw new DBUnexpectedError(
2815                                         $this,
2816                                         "$fname: Expected mass rollback of all peer databases (DBO_TRX set)."
2817                                 );
2818                         }
2819                 }
2820
2821                 // Avoid fatals if close() was called
2822                 $this->assertOpen();
2823
2824                 $this->doRollback( $fname );
2825                 $this->mTrxAtomicLevels = [];
2826                 if ( $this->mTrxDoneWrites ) {
2827                         $this->trxProfiler->transactionWritingOut(
2828                                 $this->mServer, $this->mDBname, $this->mTrxShortId );
2829                 }
2830
2831                 $this->mTrxIdleCallbacks = []; // clear
2832                 $this->mTrxPreCommitCallbacks = []; // clear
2833                 $this->runOnTransactionIdleCallbacks( self::TRIGGER_ROLLBACK );
2834                 $this->runTransactionListenerCallbacks( self::TRIGGER_ROLLBACK );
2835         }
2836
2837         /**
2838          * Issues the ROLLBACK command to the database server.
2839          *
2840          * @see Database::rollback()
2841          * @param string $fname
2842          */
2843         protected function doRollback( $fname ) {
2844                 if ( $this->mTrxLevel ) {
2845                         # Disconnects cause rollback anyway, so ignore those errors
2846                         $ignoreErrors = true;
2847                         $this->query( 'ROLLBACK', $fname, $ignoreErrors );
2848                         $this->mTrxLevel = 0;
2849                 }
2850         }
2851
2852         public function flushSnapshot( $fname = __METHOD__ ) {
2853                 if ( $this->writesOrCallbacksPending() || $this->explicitTrxActive() ) {
2854                         // This only flushes transactions to clear snapshots, not to write data
2855                         $fnames = implode( ', ', $this->pendingWriteAndCallbackCallers() );
2856                         throw new DBUnexpectedError(
2857                                 $this,
2858                                 "$fname: Cannot flush snapshot because writes are pending ($fnames)."
2859                         );
2860                 }
2861
2862                 $this->commit( $fname, self::FLUSHING_INTERNAL );
2863         }
2864
2865         public function explicitTrxActive() {
2866                 return $this->mTrxLevel && ( $this->mTrxAtomicLevels || !$this->mTrxAutomatic );
2867         }
2868
2869         public function duplicateTableStructure(
2870                 $oldName, $newName, $temporary = false, $fname = __METHOD__
2871         ) {
2872                 throw new RuntimeException( __METHOD__ . ' is not implemented in descendant class' );
2873         }
2874
2875         public function listTables( $prefix = null, $fname = __METHOD__ ) {
2876                 throw new RuntimeException( __METHOD__ . ' is not implemented in descendant class' );
2877         }
2878
2879         public function listViews( $prefix = null, $fname = __METHOD__ ) {
2880                 throw new RuntimeException( __METHOD__ . ' is not implemented in descendant class' );
2881         }
2882
2883         public function timestamp( $ts = 0 ) {
2884                 $t = new ConvertibleTimestamp( $ts );
2885                 // Let errors bubble up to avoid putting garbage in the DB
2886                 return $t->getTimestamp( TS_MW );
2887         }
2888
2889         public function timestampOrNull( $ts = null ) {
2890                 if ( is_null( $ts ) ) {
2891                         return null;
2892                 } else {
2893                         return $this->timestamp( $ts );
2894                 }
2895         }
2896
2897         /**
2898          * Take the result from a query, and wrap it in a ResultWrapper if
2899          * necessary. Boolean values are passed through as is, to indicate success
2900          * of write queries or failure.
2901          *
2902          * Once upon a time, Database::query() returned a bare MySQL result
2903          * resource, and it was necessary to call this function to convert it to
2904          * a wrapper. Nowadays, raw database objects are never exposed to external
2905          * callers, so this is unnecessary in external code.
2906          *
2907          * @param bool|ResultWrapper|resource|object $result
2908          * @return bool|ResultWrapper
2909          */
2910         protected function resultObject( $result ) {
2911                 if ( !$result ) {
2912                         return false;
2913                 } elseif ( $result instanceof ResultWrapper ) {
2914                         return $result;
2915                 } elseif ( $result === true ) {
2916                         // Successful write query
2917                         return $result;
2918                 } else {
2919                         return new ResultWrapper( $this, $result );
2920                 }
2921         }
2922
2923         public function ping( &$rtt = null ) {
2924                 // Avoid hitting the server if it was hit recently
2925                 if ( $this->isOpen() && ( microtime( true ) - $this->lastPing ) < self::PING_TTL ) {
2926                         if ( !func_num_args() || $this->mRTTEstimate > 0 ) {
2927                                 $rtt = $this->mRTTEstimate;
2928                                 return true; // don't care about $rtt
2929                         }
2930                 }
2931
2932                 // This will reconnect if possible or return false if not
2933                 $this->clearFlag( self::DBO_TRX, self::REMEMBER_PRIOR );
2934                 $ok = ( $this->query( self::PING_QUERY, __METHOD__, true ) !== false );
2935                 $this->restoreFlags( self::RESTORE_PRIOR );
2936
2937                 if ( $ok ) {
2938                         $rtt = $this->mRTTEstimate;
2939                 }
2940
2941                 return $ok;
2942         }
2943
2944         /**
2945          * @return bool
2946          */
2947         protected function reconnect() {
2948                 $this->closeConnection();
2949                 $this->mOpened = false;
2950                 $this->mConn = false;
2951                 try {
2952                         $this->open( $this->mServer, $this->mUser, $this->mPassword, $this->mDBname );
2953                         $this->lastPing = microtime( true );
2954                         $ok = true;
2955                 } catch ( DBConnectionError $e ) {
2956                         $ok = false;
2957                 }
2958
2959                 return $ok;
2960         }
2961
2962         public function getSessionLagStatus() {
2963                 return $this->getTransactionLagStatus() ?: $this->getApproximateLagStatus();
2964         }
2965
2966         /**
2967          * Get the replica DB lag when the current transaction started
2968          *
2969          * This is useful when transactions might use snapshot isolation
2970          * (e.g. REPEATABLE-READ in innodb), so the "real" lag of that data
2971          * is this lag plus transaction duration. If they don't, it is still
2972          * safe to be pessimistic. This returns null if there is no transaction.
2973          *
2974          * @return array|null ('lag': seconds or false on error, 'since': UNIX timestamp of BEGIN)
2975          * @since 1.27
2976          */
2977         protected function getTransactionLagStatus() {
2978                 return $this->mTrxLevel
2979                         ? [ 'lag' => $this->mTrxReplicaLag, 'since' => $this->trxTimestamp() ]
2980                         : null;
2981         }
2982
2983         /**
2984          * Get a replica DB lag estimate for this server
2985          *
2986          * @return array ('lag': seconds or false on error, 'since': UNIX timestamp of estimate)
2987          * @since 1.27
2988          */
2989         protected function getApproximateLagStatus() {
2990                 return [
2991                         'lag'   => $this->getLBInfo( 'replica' ) ? $this->getLag() : 0,
2992                         'since' => microtime( true )
2993                 ];
2994         }
2995
2996         /**
2997          * Merge the result of getSessionLagStatus() for several DBs
2998          * using the most pessimistic values to estimate the lag of
2999          * any data derived from them in combination
3000          *
3001          * This is information is useful for caching modules
3002          *
3003          * @see WANObjectCache::set()
3004          * @see WANObjectCache::getWithSetCallback()
3005          *
3006          * @param IDatabase $db1
3007          * @param IDatabase ...
3008          * @return array Map of values:
3009          *   - lag: highest lag of any of the DBs or false on error (e.g. replication stopped)
3010          *   - since: oldest UNIX timestamp of any of the DB lag estimates
3011          *   - pending: whether any of the DBs have uncommitted changes
3012          * @since 1.27
3013          */
3014         public static function getCacheSetOptions( IDatabase $db1 ) {
3015                 $res = [ 'lag' => 0, 'since' => INF, 'pending' => false ];
3016                 foreach ( func_get_args() as $db ) {
3017                         /** @var IDatabase $db */
3018                         $status = $db->getSessionLagStatus();
3019                         if ( $status['lag'] === false ) {
3020                                 $res['lag'] = false;
3021                         } elseif ( $res['lag'] !== false ) {
3022                                 $res['lag'] = max( $res['lag'], $status['lag'] );
3023                         }
3024                         $res['since'] = min( $res['since'], $status['since'] );
3025                         $res['pending'] = $res['pending'] ?: $db->writesPending();
3026                 }
3027
3028                 return $res;
3029         }
3030
3031         public function getLag() {
3032                 return 0;
3033         }
3034
3035         public function maxListLen() {
3036                 return 0;
3037         }
3038
3039         public function encodeBlob( $b ) {
3040                 return $b;
3041         }
3042
3043         public function decodeBlob( $b ) {
3044                 if ( $b instanceof Blob ) {
3045                         $b = $b->fetch();
3046                 }
3047                 return $b;
3048         }
3049
3050         public function setSessionOptions( array $options ) {
3051         }
3052
3053         public function sourceFile(
3054                 $filename,
3055                 callable $lineCallback = null,
3056                 callable $resultCallback = null,
3057                 $fname = false,
3058                 callable $inputCallback = null
3059         ) {
3060                 MediaWiki\suppressWarnings();
3061                 $fp = fopen( $filename, 'r' );
3062                 MediaWiki\restoreWarnings();
3063
3064                 if ( false === $fp ) {
3065                         throw new RuntimeException( "Could not open \"{$filename}\".\n" );
3066                 }
3067
3068                 if ( !$fname ) {
3069                         $fname = __METHOD__ . "( $filename )";
3070                 }
3071
3072                 try {
3073                         $error = $this->sourceStream(
3074                                 $fp, $lineCallback, $resultCallback, $fname, $inputCallback );
3075                 } catch ( Exception $e ) {
3076                         fclose( $fp );
3077                         throw $e;
3078                 }
3079
3080                 fclose( $fp );
3081
3082                 return $error;
3083         }
3084
3085         public function setSchemaVars( $vars ) {
3086                 $this->mSchemaVars = $vars;
3087         }
3088
3089         public function sourceStream(
3090                 $fp,
3091                 callable $lineCallback = null,
3092                 callable $resultCallback = null,
3093                 $fname = __METHOD__,
3094                 callable $inputCallback = null
3095         ) {
3096                 $cmd = '';
3097
3098                 while ( !feof( $fp ) ) {
3099                         if ( $lineCallback ) {
3100                                 call_user_func( $lineCallback );
3101                         }
3102
3103                         $line = trim( fgets( $fp ) );
3104
3105                         if ( $line == '' ) {
3106                                 continue;
3107                         }
3108
3109                         if ( '-' == $line[0] && '-' == $line[1] ) {
3110                                 continue;
3111                         }
3112
3113                         if ( $cmd != '' ) {
3114                                 $cmd .= ' ';
3115                         }
3116
3117                         $done = $this->streamStatementEnd( $cmd, $line );
3118
3119                         $cmd .= "$line\n";
3120
3121                         if ( $done || feof( $fp ) ) {
3122                                 $cmd = $this->replaceVars( $cmd );
3123
3124                                 if ( !$inputCallback || call_user_func( $inputCallback, $cmd ) ) {
3125                                         $res = $this->query( $cmd, $fname );
3126
3127                                         if ( $resultCallback ) {
3128                                                 call_user_func( $resultCallback, $res, $this );
3129                                         }
3130
3131                                         if ( false === $res ) {
3132                                                 $err = $this->lastError();
3133
3134                                                 return "Query \"{$cmd}\" failed with error code \"$err\".\n";
3135                                         }
3136                                 }
3137                                 $cmd = '';
3138                         }
3139                 }
3140
3141                 return true;
3142         }
3143
3144         /**
3145          * Called by sourceStream() to check if we've reached a statement end
3146          *
3147          * @param string &$sql SQL assembled so far
3148          * @param string &$newLine New line about to be added to $sql
3149          * @return bool Whether $newLine contains end of the statement
3150          */
3151         public function streamStatementEnd( &$sql, &$newLine ) {
3152                 if ( $this->delimiter ) {
3153                         $prev = $newLine;
3154                         $newLine = preg_replace(
3155                                 '/' . preg_quote( $this->delimiter, '/' ) . '$/', '', $newLine );
3156                         if ( $newLine != $prev ) {
3157                                 return true;
3158                         }
3159                 }
3160
3161                 return false;
3162         }
3163
3164         /**
3165          * Database independent variable replacement. Replaces a set of variables
3166          * in an SQL statement with their contents as given by $this->getSchemaVars().
3167          *
3168          * Supports '{$var}' `{$var}` and / *$var* / (without the spaces) style variables.
3169          *
3170          * - '{$var}' should be used for text and is passed through the database's
3171          *   addQuotes method.
3172          * - `{$var}` should be used for identifiers (e.g. table and database names).
3173          *   It is passed through the database's addIdentifierQuotes method which
3174          *   can be overridden if the database uses something other than backticks.
3175          * - / *_* / or / *$wgDBprefix* / passes the name that follows through the
3176          *   database's tableName method.
3177          * - / *i* / passes the name that follows through the database's indexName method.
3178          * - In all other cases, / *$var* / is left unencoded. Except for table options,
3179          *   its use should be avoided. In 1.24 and older, string encoding was applied.
3180          *
3181          * @param string $ins SQL statement to replace variables in
3182          * @return string The new SQL statement with variables replaced
3183          */
3184         protected function replaceVars( $ins ) {
3185                 $vars = $this->getSchemaVars();
3186                 return preg_replace_callback(
3187                         '!
3188                                 /\* (\$wgDBprefix|[_i]) \*/ (\w*) | # 1-2. tableName, indexName
3189                                 \'\{\$ (\w+) }\'                  | # 3. addQuotes
3190                                 `\{\$ (\w+) }`                    | # 4. addIdentifierQuotes
3191                                 /\*\$ (\w+) \*/                     # 5. leave unencoded
3192                         !x',
3193                         function ( $m ) use ( $vars ) {
3194                                 // Note: Because of <https://bugs.php.net/bug.php?id=51881>,
3195                                 // check for both nonexistent keys *and* the empty string.
3196                                 if ( isset( $m[1] ) && $m[1] !== '' ) {
3197                                         if ( $m[1] === 'i' ) {
3198                                                 return $this->indexName( $m[2] );
3199                                         } else {
3200                                                 return $this->tableName( $m[2] );
3201                                         }
3202                                 } elseif ( isset( $m[3] ) && $m[3] !== '' && array_key_exists( $m[3], $vars ) ) {
3203                                         return $this->addQuotes( $vars[$m[3]] );
3204                                 } elseif ( isset( $m[4] ) && $m[4] !== '' && array_key_exists( $m[4], $vars ) ) {
3205                                         return $this->addIdentifierQuotes( $vars[$m[4]] );
3206                                 } elseif ( isset( $m[5] ) && $m[5] !== '' && array_key_exists( $m[5], $vars ) ) {
3207                                         return $vars[$m[5]];
3208                                 } else {
3209                                         return $m[0];
3210                                 }
3211                         },
3212                         $ins
3213                 );
3214         }
3215
3216         /**
3217          * Get schema variables. If none have been set via setSchemaVars(), then
3218          * use some defaults from the current object.
3219          *
3220          * @return array
3221          */
3222         protected function getSchemaVars() {
3223                 if ( $this->mSchemaVars ) {
3224                         return $this->mSchemaVars;
3225                 } else {
3226                         return $this->getDefaultSchemaVars();
3227                 }
3228         }
3229
3230         /**
3231          * Get schema variables to use if none have been set via setSchemaVars().
3232          *
3233          * Override this in derived classes to provide variables for tables.sql
3234          * and SQL patch files.
3235          *
3236          * @return array
3237          */
3238         protected function getDefaultSchemaVars() {
3239                 return [];
3240         }
3241
3242         public function lockIsFree( $lockName, $method ) {
3243                 return true;
3244         }
3245
3246         public function lock( $lockName, $method, $timeout = 5 ) {
3247                 $this->mNamedLocksHeld[$lockName] = 1;
3248
3249                 return true;
3250         }
3251
3252         public function unlock( $lockName, $method ) {
3253                 unset( $this->mNamedLocksHeld[$lockName] );
3254
3255                 return true;
3256         }
3257
3258         public function getScopedLockAndFlush( $lockKey, $fname, $timeout ) {
3259                 if ( $this->writesOrCallbacksPending() ) {
3260                         // This only flushes transactions to clear snapshots, not to write data
3261                         $fnames = implode( ', ', $this->pendingWriteAndCallbackCallers() );
3262                         throw new DBUnexpectedError(
3263                                 $this,
3264                                 "$fname: Cannot flush pre-lock snapshot because writes are pending ($fnames)."
3265                         );
3266                 }
3267
3268                 if ( !$this->lock( $lockKey, $fname, $timeout ) ) {
3269                         return null;
3270                 }
3271
3272                 $unlocker = new ScopedCallback( function () use ( $lockKey, $fname ) {
3273                         if ( $this->trxLevel() ) {
3274                                 // There is a good chance an exception was thrown, causing any early return
3275                                 // from the caller. Let any error handler get a chance to issue rollback().
3276                                 // If there isn't one, let the error bubble up and trigger server-side rollback.
3277                                 $this->onTransactionResolution(
3278                                         function () use ( $lockKey, $fname ) {
3279                                                 $this->unlock( $lockKey, $fname );
3280                                         },
3281                                         $fname
3282                                 );
3283                         } else {
3284                                 $this->unlock( $lockKey, $fname );
3285                         }
3286                 } );
3287
3288                 $this->commit( $fname, self::FLUSHING_INTERNAL );
3289
3290                 return $unlocker;
3291         }
3292
3293         public function namedLocksEnqueue() {
3294                 return false;
3295         }
3296
3297         /**
3298          * Lock specific tables
3299          *
3300          * @param array $read Array of tables to lock for read access
3301          * @param array $write Array of tables to lock for write access
3302          * @param string $method Name of caller
3303          * @param bool $lowPriority Whether to indicate writes to be LOW PRIORITY
3304          * @return bool
3305          */
3306         public function lockTables( $read, $write, $method, $lowPriority = true ) {
3307                 return true;
3308         }
3309
3310         /**
3311          * Unlock specific tables
3312          *
3313          * @param string $method The caller
3314          * @return bool
3315          */
3316         public function unlockTables( $method ) {
3317                 return true;
3318         }
3319
3320         /**
3321          * Delete a table
3322          * @param string $tableName
3323          * @param string $fName
3324          * @return bool|ResultWrapper
3325          * @since 1.18
3326          */
3327         public function dropTable( $tableName, $fName = __METHOD__ ) {
3328                 if ( !$this->tableExists( $tableName, $fName ) ) {
3329                         return false;
3330                 }
3331                 $sql = "DROP TABLE " . $this->tableName( $tableName ) . " CASCADE";
3332
3333                 return $this->query( $sql, $fName );
3334         }
3335
3336         public function getInfinity() {
3337                 return 'infinity';
3338         }
3339
3340         public function encodeExpiry( $expiry ) {
3341                 return ( $expiry == '' || $expiry == 'infinity' || $expiry == $this->getInfinity() )
3342                         ? $this->getInfinity()
3343                         : $this->timestamp( $expiry );
3344         }
3345
3346         public function decodeExpiry( $expiry, $format = TS_MW ) {
3347                 if ( $expiry == '' || $expiry == 'infinity' || $expiry == $this->getInfinity() ) {
3348                         return 'infinity';
3349                 }
3350
3351                 return ConvertibleTimestamp::convert( $format, $expiry );
3352         }
3353
3354         public function setBigSelects( $value = true ) {
3355                 // no-op
3356         }
3357
3358         public function isReadOnly() {
3359                 return ( $this->getReadOnlyReason() !== false );
3360         }
3361
3362         /**
3363          * @return string|bool Reason this DB is read-only or false if it is not
3364          */
3365         protected function getReadOnlyReason() {
3366                 $reason = $this->getLBInfo( 'readOnlyReason' );
3367
3368                 return is_string( $reason ) ? $reason : false;
3369         }
3370
3371         public function setTableAliases( array $aliases ) {
3372                 $this->tableAliases = $aliases;
3373         }
3374
3375         /**
3376          * @return bool Whether a DB user is required to access the DB
3377          * @since 1.28
3378          */
3379         protected function requiresDatabaseUser() {
3380                 return true;
3381         }
3382
3383         /**
3384          * Get the underlying binding handle, mConn
3385          *
3386          * Makes sure that mConn is set (disconnects and ping() failure can unset it).
3387          * This catches broken callers than catch and ignore disconnection exceptions.
3388          * Unlike checking isOpen(), this is safe to call inside of open().
3389          *
3390          * @return resource|object
3391          * @throws DBUnexpectedError
3392          * @since 1.26
3393          */
3394         protected function getBindingHandle() {
3395                 if ( !$this->mConn ) {
3396                         throw new DBUnexpectedError(
3397                                 $this,
3398                                 'DB connection was already closed or the connection dropped.'
3399                         );
3400                 }
3401
3402                 return $this->mConn;
3403         }
3404
3405         /**
3406          * @since 1.19
3407          * @return string
3408          */
3409         public function __toString() {
3410                 return (string)$this->mConn;
3411         }
3412
3413         /**
3414          * Make sure that copies do not share the same client binding handle
3415          * @throws DBConnectionError
3416          */
3417         public function __clone() {
3418                 $this->connLogger->warning(
3419                         "Cloning " . get_class( $this ) . " is not recomended; forking connection:\n" .
3420                         ( new RuntimeException() )->getTraceAsString()
3421                 );
3422
3423                 if ( $this->isOpen() ) {
3424                         // Open a new connection resource without messing with the old one
3425                         $this->mOpened = false;
3426                         $this->mConn = false;
3427                         $this->mTrxEndCallbacks = []; // don't copy
3428                         $this->handleSessionLoss(); // no trx or locks anymore
3429                         $this->open( $this->mServer, $this->mUser, $this->mPassword, $this->mDBname );
3430                         $this->lastPing = microtime( true );
3431                 }
3432         }
3433
3434         /**
3435          * Called by serialize. Throw an exception when DB connection is serialized.
3436          * This causes problems on some database engines because the connection is
3437          * not restored on unserialize.
3438          */
3439         public function __sleep() {
3440                 throw new RuntimeException( 'Database serialization may cause problems, since ' .
3441                         'the connection is not restored on wakeup.' );
3442         }
3443
3444         /**
3445          * Run a few simple sanity checks and close dangling connections
3446          */
3447         public function __destruct() {
3448                 if ( $this->mTrxLevel && $this->mTrxDoneWrites ) {
3449                         trigger_error( "Uncommitted DB writes (transaction from {$this->mTrxFname})." );
3450                 }
3451
3452                 $danglingWriters = $this->pendingWriteAndCallbackCallers();
3453                 if ( $danglingWriters ) {
3454                         $fnames = implode( ', ', $danglingWriters );
3455                         trigger_error( "DB transaction writes or callbacks still pending ($fnames)." );
3456                 }
3457
3458                 if ( $this->mConn ) {
3459                         // Avoid connection leaks for sanity. Normally, resources close at script completion.
3460                         // The connection might already be closed in zend/hhvm by now, so suppress warnings.
3461                         \MediaWiki\suppressWarnings();
3462                         $this->closeConnection();
3463                         \MediaWiki\restoreWarnings();
3464                         $this->mConn = false;
3465                         $this->mOpened = false;
3466                 }
3467         }
3468 }
3469
3470 class_alias( 'Database', 'DatabaseBase' );