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 use Wikimedia\Timestamp\ConvertibleTimestamp;
  35
  36 /**
  37  * Relational database abstraction object
  38  *
  39  * @ingroup Database
  40  * @since 1.28
  41  */
  42 abstract class Database implements IDatabase, IMaintainableDatabase, LoggerAwareInterface {
  43         /** Number of times to re-try an operation in case of deadlock */
  44         const DEADLOCK_TRIES = 4;
  45         /** Minimum time to wait before retry, in microseconds */
  46         const DEADLOCK_DELAY_MIN = 500000;
  47         /** Maximum time to wait before retry */
  48         const DEADLOCK_DELAY_MAX = 1500000;
  49
  50         /** How long before it is worth doing a dummy query to test the connection */
  51         const PING_TTL = 1.0;
  52         const PING_QUERY = 'SELECT 1 AS ping';
  53
  54         const TINY_WRITE_SEC = .010;
  55         const SLOW_WRITE_SEC = .500;
  56         const SMALL_WRITE_ROWS = 100;
  57
  58         /** @var string SQL query */
  59         protected $mLastQuery = '';
  60         /** @var float|bool UNIX timestamp of last write query */
  61         protected $mLastWriteTime = false;
  62         /** @var string|bool */
  63         protected $mPHPError = false;
  64         /** @var string */
  65         protected $mServer;
  66         /** @var string */
  67         protected $mUser;
  68         /** @var string */
  69         protected $mPassword;
  70         /** @var string */
  71         protected $mDBname;
  72         /** @var array[] $aliases Map of (table => (dbname, schema, prefix) map) */
  73         protected $tableAliases = [];
  74         /** @var bool Whether this PHP instance is for a CLI script */
  75         protected $cliMode;
  76         /** @var string Agent name for query profiling */
  77         protected $agent;
  78
  79         /** @var BagOStuff APC cache */
  80         protected $srvCache;
  81         /** @var LoggerInterface */
  82         protected $connLogger;
  83         /** @var LoggerInterface */
  84         protected $queryLogger;
  85         /** @var callback Error logging callback */
  86         protected $errorLogger;
  87
  88         /** @var resource|null Database connection */
  89         protected $mConn = null;
  90         /** @var bool */
  91         protected $mOpened = false;
  92
  93         /** @var array[] List of (callable, method name) */
  94         protected $mTrxIdleCallbacks = [];
  95         /** @var array[] List of (callable, method name) */
  96         protected $mTrxPreCommitCallbacks = [];
  97         /** @var array[] List of (callable, method name) */
  98         protected $mTrxEndCallbacks = [];
  99         /** @var callable[] Map of (name => callable) */
 100         protected $mTrxRecurringCallbacks = [];
 101         /** @var bool Whether to suppress triggering of transaction end callbacks */
 102         protected $mTrxEndCallbacksSuppressed = false;
 103
 104         /** @var string */
 105         protected $mTablePrefix = '';
 106         /** @var string */
 107         protected $mSchema = '';
 108         /** @var integer */
 109         protected $mFlags;
 110         /** @var array */
 111         protected $mLBInfo = [];
 112         /** @var bool|null */
 113         protected $mDefaultBigSelects = null;
 114         /** @var array|bool */
 115         protected $mSchemaVars = false;
 116         /** @var array */
 117         protected $mSessionVars = [];
 118         /** @var array|null */
 119         protected $preparedArgs;
 120         /** @var string|bool|null Stashed value of html_errors INI setting */
 121         protected $htmlErrors;
 122         /** @var string */
 123         protected $delimiter = ';';
 124         /** @var DatabaseDomain */
 125         protected $currentDomain;
 126
 127         /**
 128          * Either 1 if a transaction is active or 0 otherwise.
 129          * The other Trx fields may not be meaningfull if this is 0.
 130          *
 131          * @var int
 132          */
 133         protected $mTrxLevel = 0;
 134         /**
 135          * Either a short hexidecimal string if a transaction is active or ""
 136          *
 137          * @var string
 138          * @see Database::mTrxLevel
 139          */
 140         protected $mTrxShortId = '';
 141         /**
 142          * The UNIX time that the transaction started. Callers can assume that if
 143          * snapshot isolation is used, then the data is *at least* up to date to that
 144          * point (possibly more up-to-date since the first SELECT defines the snapshot).
 145          *
 146          * @var float|null
 147          * @see Database::mTrxLevel
 148          */
 149         private $mTrxTimestamp = null;
 150         /** @var float Lag estimate at the time of BEGIN */
 151         private $mTrxReplicaLag = null;
 152         /**
 153          * Remembers the function name given for starting the most recent transaction via begin().
 154          * Used to provide additional context for error reporting.
 155          *
 156          * @var string
 157          * @see Database::mTrxLevel
 158          */
 159         private $mTrxFname = null;
 160         /**
 161          * Record if possible write queries were done in the last transaction started
 162          *
 163          * @var bool
 164          * @see Database::mTrxLevel
 165          */
 166         private $mTrxDoneWrites = false;
 167         /**
 168          * Record if the current transaction was started implicitly due to DBO_TRX being set.
 169          *
 170          * @var bool
 171          * @see Database::mTrxLevel
 172          */
 173         private $mTrxAutomatic = false;
 174         /**
 175          * Array of levels of atomicity within transactions
 176          *
 177          * @var array
 178          */
 179         private $mTrxAtomicLevels = [];
 180         /**
 181          * Record if the current transaction was started implicitly by Database::startAtomic
 182          *
 183          * @var bool
 184          */
 185         private $mTrxAutomaticAtomic = false;
 186         /**
 187          * Track the write query callers of the current transaction
 188          *
 189          * @var string[]
 190          */
 191         private $mTrxWriteCallers = [];
 192         /**
 193          * @var float Seconds spent in write queries for the current transaction
 194          */
 195         private $mTrxWriteDuration = 0.0;
 196         /**
 197          * @var integer Number of write queries for the current transaction
 198          */
 199         private $mTrxWriteQueryCount = 0;
 200         /**
 201          * @var float Like mTrxWriteQueryCount but excludes lock-bound, easy to replicate, queries
 202          */
 203         private $mTrxWriteAdjDuration = 0.0;
 204         /**
 205          * @var integer Number of write queries counted in mTrxWriteAdjDuration
 206          */
 207         private $mTrxWriteAdjQueryCount = 0;
 208         /**
 209          * @var float RTT time estimate
 210          */
 211         private $mRTTEstimate = 0.0;
 212
 213         /** @var array Map of (name => 1) for locks obtained via lock() */
 214         private $mNamedLocksHeld = [];
 215         /** @var array Map of (table name => 1) for TEMPORARY tables */
 216         protected $mSessionTempTables = [];
 217
 218         /** @var IDatabase|null Lazy handle to the master DB this server replicates from */
 219         private $lazyMasterHandle;
 220
 221         /** @var float UNIX timestamp */
 222         protected $lastPing = 0.0;
 223
 224         /** @var int[] Prior mFlags values */
 225         private $priorFlags = [];
 226
 227         /** @var object|string Class name or object With profileIn/profileOut methods */
 228         protected $profiler;
 229         /** @var TransactionProfiler */
 230         protected $trxProfiler;
 231
 232         /**
 233          * Constructor and database handle and attempt to connect to the DB server
 234          *
 235          * IDatabase classes should not be constructed directly in external
 236          * code. Database::factory() should be used instead.
 237          *
 238          * @param array $params Parameters passed from Database::factory()
 239          */
 240         function __construct( array $params ) {
 241                 $server = $params['host'];
 242                 $user = $params['user'];
 243                 $password = $params['password'];
 244                 $dbName = $params['dbname'];
 245
 246                 $this->mSchema = $params['schema'];
 247                 $this->mTablePrefix = $params['tablePrefix'];
 248
 249                 $this->cliMode = $params['cliMode'];
 250                 // Agent name is added to SQL queries in a comment, so make sure it can't break out
 251                 $this->agent = str_replace( '/', '-', $params['agent'] );
 252
 253                 $this->mFlags = $params['flags'];
 254                 if ( $this->mFlags & self::DBO_DEFAULT ) {
 255                         if ( $this->cliMode ) {
 256                                 $this->mFlags &= ~self::DBO_TRX;
 257                         } else {
 258                                 $this->mFlags |= self::DBO_TRX;
 259                         }
 260                 }
 261
 262                 $this->mSessionVars = $params['variables'];
 263
 264                 $this->srvCache = isset( $params['srvCache'] )
 265                         ? $params['srvCache']
 266                         : new HashBagOStuff();
 267
 268                 $this->profiler = $params['profiler'];
 269                 $this->trxProfiler = $params['trxProfiler'];
 270                 $this->connLogger = $params['connLogger'];
 271                 $this->queryLogger = $params['queryLogger'];
 272                 $this->errorLogger = $params['errorLogger'];
 273
 274                 // Set initial dummy domain until open() sets the final DB/prefix
 275                 $this->currentDomain = DatabaseDomain::newUnspecified();
 276
 277                 if ( $user ) {
 278                         $this->open( $server, $user, $password, $dbName );
 279                 } elseif ( $this->requiresDatabaseUser() ) {
 280                         throw new InvalidArgumentException( "No database user provided." );
 281                 }
 282
 283                 // Set the domain object after open() sets the relevant fields
 284                 if ( $this->mDBname != '' ) {
 285                         // Domains with server scope but a table prefix are not used by IDatabase classes
 286                         $this->currentDomain = new DatabaseDomain( $this->mDBname, null, $this->mTablePrefix );
 287                 }
 288         }
 289
 290         /**
 291          * Construct a Database subclass instance given a database type and parameters
 292          *
 293          * This also connects to the database immediately upon object construction
 294          *
 295          * @param string $dbType A possible DB type (sqlite, mysql, postgres)
 296          * @param array $p Parameter map with keys:
 297          *   - host : The hostname of the DB server
 298          *   - user : The name of the database user the client operates under
 299          *   - password : The password for the database user
 300          *   - dbname : The name of the database to use where queries do not specify one.
 301          *      The database must exist or an error might be thrown. Setting this to the empty string
 302          *      will avoid any such errors and make the handle have no implicit database scope. This is
 303          *      useful for queries like SHOW STATUS, CREATE DATABASE, or DROP DATABASE. Note that a
 304          *      "database" in Postgres is rougly equivalent to an entire MySQL server. This the domain
 305          *      in which user names and such are defined, e.g. users are database-specific in Postgres.
 306          *   - schema : The database schema to use (if supported). A "schema" in Postgres is roughly
 307          *      equivalent to a "database" in MySQL. Note that MySQL and SQLite do not use schemas.
 308          *   - tablePrefix : Optional table prefix that is implicitly added on to all table names
 309          *      recognized in queries. This can be used in place of schemas for handle site farms.
 310          *   - flags : Optional bitfield of DBO_* constants that define connection, protocol,
 311          *      buffering, and transaction behavior. It is STRONGLY adviced to leave the DBO_DEFAULT
 312          *      flag in place UNLESS this this database simply acts as a key/value store.
 313          *   - driver: Optional name of a specific DB client driver. For MySQL, there is the old
 314          *      'mysql' driver and the newer 'mysqli' driver.
 315          *   - variables: Optional map of session variables to set after connecting. This can be
 316          *      used to adjust lock timeouts or encoding modes and the like.
 317          *   - connLogger: Optional PSR-3 logger interface instance.
 318          *   - queryLogger: Optional PSR-3 logger interface instance.
 319          *   - profiler: Optional class name or object with profileIn()/profileOut() methods.
 320          *      These will be called in query(), using a simplified version of the SQL that also
 321          *      includes the agent as a SQL comment.
 322          *   - trxProfiler: Optional TransactionProfiler instance.
 323          *   - errorLogger: Optional callback that takes an Exception and logs it.
 324          *   - cliMode: Whether to consider the execution context that of a CLI script.
 325          *   - agent: Optional name used to identify the end-user in query profiling/logging.
 326          *   - srvCache: Optional BagOStuff instance to an APC-style cache.
 327          * @return Database|null If the database driver or extension cannot be found
 328          * @throws InvalidArgumentException If the database driver or extension cannot be found
 329          * @since 1.18
 330          */
 331         final public static function factory( $dbType, $p = [] ) {
 332                 static $canonicalDBTypes = [
 333                         'mysql' => [ 'mysqli', 'mysql' ],
 334                         'postgres' => [],
 335                         'sqlite' => [],
 336                         'oracle' => [],
 337                         'mssql' => [],
 338                 ];
 339
 340                 $driver = false;
 341                 $dbType = strtolower( $dbType );
 342                 if ( isset( $canonicalDBTypes[$dbType] ) && $canonicalDBTypes[$dbType] ) {
 343                         $possibleDrivers = $canonicalDBTypes[$dbType];
 344                         if ( !empty( $p['driver'] ) ) {
 345                                 if ( in_array( $p['driver'], $possibleDrivers ) ) {
 346                                         $driver = $p['driver'];
 347                                 } else {
 348                                         throw new InvalidArgumentException( __METHOD__ .
 349                                                 " type '$dbType' does not support driver '{$p['driver']}'" );
 350                                 }
 351                         } else {
 352                                 foreach ( $possibleDrivers as $posDriver ) {
 353                                         if ( extension_loaded( $posDriver ) ) {
 354                                                 $driver = $posDriver;
 355                                                 break;
 356                                         }
 357                                 }
 358                         }
 359                 } else {
 360                         $driver = $dbType;
 361                 }
 362                 if ( $driver === false || $driver === '' ) {
 363                         throw new InvalidArgumentException( __METHOD__ .
 364                                 " no viable database extension found for type '$dbType'" );
 365                 }
 366
 367                 $class = 'Database' . ucfirst( $driver );
 368                 if ( class_exists( $class ) && is_subclass_of( $class, 'IDatabase' ) ) {
 369                         // Resolve some defaults for b/c
 370                         $p['host'] = isset( $p['host'] ) ? $p['host'] : false;
 371                         $p['user'] = isset( $p['user'] ) ? $p['user'] : false;
 372                         $p['password'] = isset( $p['password'] ) ? $p['password'] : false;
 373                         $p['dbname'] = isset( $p['dbname'] ) ? $p['dbname'] : false;
 374                         $p['flags'] = isset( $p['flags'] ) ? $p['flags'] : 0;
 375                         $p['variables'] = isset( $p['variables'] ) ? $p['variables'] : [];
 376                         $p['tablePrefix'] = isset( $p['tablePrefix'] ) ? $p['tablePrefix'] : '';
 377                         $p['schema'] = isset( $p['schema'] ) ? $p['schema'] : '';
 378                         $p['cliMode'] = isset( $p['cliMode'] ) ? $p['cliMode'] : ( PHP_SAPI === 'cli' );
 379                         $p['agent'] = isset( $p['agent'] ) ? $p['agent'] : '';
 380                         if ( !isset( $p['connLogger'] ) ) {
 381                                 $p['connLogger'] = new \Psr\Log\NullLogger();
 382                         }
 383                         if ( !isset( $p['queryLogger'] ) ) {
 384                                 $p['queryLogger'] = new \Psr\Log\NullLogger();
 385                         }
 386                         $p['profiler'] = isset( $p['profiler'] ) ? $p['profiler'] : null;
 387                         if ( !isset( $p['trxProfiler'] ) ) {
 388                                 $p['trxProfiler'] = new TransactionProfiler();
 389                         }
 390                         if ( !isset( $p['errorLogger'] ) ) {
 391                                 $p['errorLogger'] = function ( Exception $e ) {
 392                                         trigger_error( get_class( $e ) . ': ' . $e->getMessage(), E_USER_WARNING );
 393                                 };
 394                         }
 395
 396                         $conn = new $class( $p );
 397                 } else {
 398                         $conn = null;
 399                 }
 400
 401                 return $conn;
 402         }
 403
 404         public function setLogger( LoggerInterface $logger ) {
 405                 $this->queryLogger = $logger;
 406         }
 407
 408         public function getServerInfo() {
 409                 return $this->getServerVersion();
 410         }
 411
 412         public function bufferResults( $buffer = null ) {
 413                 $res = !$this->getFlag( self::DBO_NOBUFFER );
 414                 if ( $buffer !== null ) {
 415                         $buffer
 416                                 ? $this->clearFlag( self::DBO_NOBUFFER )
 417                                 : $this->setFlag( self::DBO_NOBUFFER );
 418                 }
 419
 420                 return $res;
 421         }
 422
 423         /**
 424          * Turns on (false) or off (true) the automatic generation and sending
 425          * of a "we're sorry, but there has been a database error" page on
 426          * database errors. Default is on (false). When turned off, the
 427          * code should use lastErrno() and lastError() to handle the
 428          * situation as appropriate.
 429          *
 430          * Do not use this function outside of the Database classes.
 431          *
 432          * @param null|bool $ignoreErrors
 433          * @return bool The previous value of the flag.
 434          */
 435         protected function ignoreErrors( $ignoreErrors = null ) {
 436                 $res = $this->getFlag( self::DBO_IGNORE );
 437                 if ( $ignoreErrors !== null ) {
 438                         $ignoreErrors
 439                                 ? $this->setFlag( self::DBO_IGNORE )
 440                                 : $this->clearFlag( self::DBO_IGNORE );
 441                 }
 442
 443                 return $res;
 444         }
 445
 446         public function trxLevel() {
 447                 return $this->mTrxLevel;
 448         }
 449
 450         public function trxTimestamp() {
 451                 return $this->mTrxLevel ? $this->mTrxTimestamp : null;
 452         }
 453
 454         public function tablePrefix( $prefix = null ) {
 455                 $old = $this->mTablePrefix;
 456                 if ( $prefix !== null ) {
 457                         $this->mTablePrefix = $prefix;
 458                         $this->currentDomain = ( $this->mDBname != '' )
 459                                 ? new DatabaseDomain( $this->mDBname, null, $this->mTablePrefix )
 460                                 : DatabaseDomain::newUnspecified();
 461                 }
 462
 463                 return $old;
 464         }
 465
 466         public function dbSchema( $schema = null ) {
 467                 $old = $this->mSchema;
 468                 if ( $schema !== null ) {
 469                         $this->mSchema = $schema;
 470                 }
 471
 472                 return $old;
 473         }
 474
 475         public function getLBInfo( $name = null ) {
 476                 if ( is_null( $name ) ) {
 477                         return $this->mLBInfo;
 478                 } else {
 479                         if ( array_key_exists( $name, $this->mLBInfo ) ) {
 480                                 return $this->mLBInfo[$name];
 481                         } else {
 482                                 return null;
 483                         }
 484                 }
 485         }
 486
 487         public function setLBInfo( $name, $value = null ) {
 488                 if ( is_null( $value ) ) {
 489                         $this->mLBInfo = $name;
 490                 } else {
 491                         $this->mLBInfo[$name] = $value;
 492                 }
 493         }
 494
 495         public function setLazyMasterHandle( IDatabase $conn ) {
 496                 $this->lazyMasterHandle = $conn;
 497         }
 498
 499         /**
 500          * @return IDatabase|null
 501          * @see setLazyMasterHandle()
 502          * @since 1.27
 503          */
 504         protected function getLazyMasterHandle() {
 505                 return $this->lazyMasterHandle;
 506         }
 507
 508         public function implicitGroupby() {
 509                 return true;
 510         }
 511
 512         public function implicitOrderby() {
 513                 return true;
 514         }
 515
 516         public function lastQuery() {
 517                 return $this->mLastQuery;
 518         }
 519
 520         public function doneWrites() {
 521                 return (bool)$this->mLastWriteTime;
 522         }
 523
 524         public function lastDoneWrites() {
 525                 return $this->mLastWriteTime ?: false;
 526         }
 527
 528         public function writesPending() {
 529                 return $this->mTrxLevel && $this->mTrxDoneWrites;
 530         }
 531
 532         public function writesOrCallbacksPending() {
 533                 return $this->mTrxLevel && (
 534                         $this->mTrxDoneWrites || $this->mTrxIdleCallbacks || $this->mTrxPreCommitCallbacks
 535                 );
 536         }
 537
 538         public function pendingWriteQueryDuration( $type = self::ESTIMATE_TOTAL ) {
 539                 if ( !$this->mTrxLevel ) {
 540                         return false;
 541                 } elseif ( !$this->mTrxDoneWrites ) {
 542                         return 0.0;
 543                 }
 544
 545                 switch ( $type ) {
 546                         case self::ESTIMATE_DB_APPLY:
 547                                 $this->ping( $rtt );
 548                                 $rttAdjTotal = $this->mTrxWriteAdjQueryCount * $rtt;
 549                                 $applyTime = max( $this->mTrxWriteAdjDuration - $rttAdjTotal, 0 );
 550                                 // For omitted queries, make them count as something at least
 551                                 $omitted = $this->mTrxWriteQueryCount - $this->mTrxWriteAdjQueryCount;
 552                                 $applyTime += self::TINY_WRITE_SEC * $omitted;
 553
 554                                 return $applyTime;
 555                         default: // everything
 556                                 return $this->mTrxWriteDuration;
 557                 }
 558         }
 559
 560         public function pendingWriteCallers() {
 561                 return $this->mTrxLevel ? $this->mTrxWriteCallers : [];
 562         }
 563
 564         protected function pendingWriteAndCallbackCallers() {
 565                 if ( !$this->mTrxLevel ) {
 566                         return [];
 567                 }
 568
 569                 $fnames = $this->mTrxWriteCallers;
 570                 foreach ( [
 571                         $this->mTrxIdleCallbacks,
 572                         $this->mTrxPreCommitCallbacks,
 573                         $this->mTrxEndCallbacks
 574                 ] as $callbacks ) {
 575                         foreach ( $callbacks as $callback ) {
 576                                 $fnames[] = $callback[1];
 577                         }
 578                 }
 579
 580                 return $fnames;
 581         }
 582
 583         public function isOpen() {
 584                 return $this->mOpened;
 585         }
 586
 587         public function setFlag( $flag, $remember = self::REMEMBER_NOTHING ) {
 588                 if ( $remember === self::REMEMBER_PRIOR ) {
 589                         array_push( $this->priorFlags, $this->mFlags );
 590                 }
 591                 $this->mFlags |= $flag;
 592         }
 593
 594         public function clearFlag( $flag, $remember = self::REMEMBER_NOTHING ) {
 595                 if ( $remember === self::REMEMBER_PRIOR ) {
 596                         array_push( $this->priorFlags, $this->mFlags );
 597                 }
 598                 $this->mFlags &= ~$flag;
 599         }
 600
 601         public function restoreFlags( $state = self::RESTORE_PRIOR ) {
 602                 if ( !$this->priorFlags ) {
 603                         return;
 604                 }
 605
 606                 if ( $state === self::RESTORE_INITIAL ) {
 607                         $this->mFlags = reset( $this->priorFlags );
 608                         $this->priorFlags = [];
 609                 } else {
 610                         $this->mFlags = array_pop( $this->priorFlags );
 611                 }
 612         }
 613
 614         public function getFlag( $flag ) {
 615                 return !!( $this->mFlags & $flag );
 616         }
 617
 618         /**
 619          * @param string $name Class field name
 620          * @return mixed
 621          * @deprecated Since 1.28
 622          */
 623         public function getProperty( $name ) {
 624                 return $this->$name;
 625         }
 626
 627         public function getDomainID() {
 628                 return $this->currentDomain->getId();
 629         }
 630
 631         final public function getWikiID() {
 632                 return $this->getDomainID();
 633         }
 634
 635         /**
 636          * Get information about an index into an object
 637          * @param string $table Table name
 638          * @param string $index Index name
 639          * @param string $fname Calling function name
 640          * @return mixed Database-specific index description class or false if the index does not exist
 641          */
 642         abstract function indexInfo( $table, $index, $fname = __METHOD__ );
 643
 644         /**
 645          * Wrapper for addslashes()
 646          *
 647          * @param string $s String to be slashed.
 648          * @return string Slashed string.
 649          */
 650         abstract function strencode( $s );
 651
 652         protected function installErrorHandler() {
 653                 $this->mPHPError = false;
 654                 $this->htmlErrors = ini_set( 'html_errors', '0' );
 655                 set_error_handler( [ $this, 'connectionErrorLogger' ] );
 656         }
 657
 658         /**
 659          * @return bool|string
 660          */
 661         protected function restoreErrorHandler() {
 662                 restore_error_handler();
 663                 if ( $this->htmlErrors !== false ) {
 664                         ini_set( 'html_errors', $this->htmlErrors );
 665                 }
 666
 667                 return $this->getLastPHPError();
 668         }
 669
 670         /**
 671          * @return string|bool Last PHP error for this DB (typically connection errors)
 672          */
 673         protected function getLastPHPError() {
 674                 if ( $this->mPHPError ) {
 675                         $error = preg_replace( '!\[<a.*</a>\]!', '', $this->mPHPError );
 676                         $error = preg_replace( '!^.*?:\s?(.*)$!', '$1', $error );
 677
 678                         return $error;
 679                 }
 680
 681                 return false;
 682         }
 683
 684         /**
 685          * This method should not be used outside of Database classes
 686          *
 687          * @param int $errno
 688          * @param string $errstr
 689          */
 690         public function connectionErrorLogger( $errno, $errstr ) {
 691                 $this->mPHPError = $errstr;
 692         }
 693
 694         /**
 695          * Create a log context to pass to PSR-3 logger functions.
 696          *
 697          * @param array $extras Additional data to add to context
 698          * @return array
 699          */
 700         protected function getLogContext( array $extras = [] ) {
 701                 return array_merge(
 702                         [
 703                                 'db_server' => $this->mServer,
 704                                 'db_name' => $this->mDBname,
 705                                 'db_user' => $this->mUser,
 706                         ],
 707                         $extras
 708                 );
 709         }
 710
 711         public function close() {
 712                 if ( $this->mConn ) {
 713                         if ( $this->trxLevel() ) {
 714                                 $this->commit( __METHOD__, self::FLUSHING_INTERNAL );
 715                         }
 716
 717                         $closed = $this->closeConnection();
 718                         $this->mConn = false;
 719                 } elseif ( $this->mTrxIdleCallbacks || $this->mTrxEndCallbacks ) { // sanity
 720                         throw new RuntimeException( "Transaction callbacks still pending." );
 721                 } else {
 722                         $closed = true;
 723                 }
 724                 $this->mOpened = false;
 725
 726                 return $closed;
 727         }
 728
 729         /**
 730          * Make sure isOpen() returns true as a sanity check
 731          *
 732          * @throws DBUnexpectedError
 733          */
 734         protected function assertOpen() {
 735                 if ( !$this->isOpen() ) {
 736                         throw new DBUnexpectedError( $this, "DB connection was already closed." );
 737                 }
 738         }
 739
 740         /**
 741          * Closes underlying database connection
 742          * @since 1.20
 743          * @return bool Whether connection was closed successfully
 744          */
 745         abstract protected function closeConnection();
 746
 747         public function reportConnectionError( $error = 'Unknown error' ) {
 748                 $myError = $this->lastError();
 749                 if ( $myError ) {
 750                         $error = $myError;
 751                 }
 752
 753                 # New method
 754                 throw new DBConnectionError( $this, $error );
 755         }
 756
 757         /**
 758          * The DBMS-dependent part of query()
 759          *
 760          * @param string $sql SQL query.
 761          * @return ResultWrapper|bool Result object to feed to fetchObject,
 762          *   fetchRow, ...; or false on failure
 763          */
 764         abstract protected function doQuery( $sql );
 765
 766         /**
 767          * Determine whether a query writes to the DB.
 768          * Should return true if unsure.
 769          *
 770          * @param string $sql
 771          * @return bool
 772          */
 773         protected function isWriteQuery( $sql ) {
 774                 return !preg_match(
 775                         '/^(?:SELECT|BEGIN|ROLLBACK|COMMIT|SET|SHOW|EXPLAIN|\(SELECT)\b/i', $sql );
 776         }
 777
 778         /**
 779          * @param $sql
 780          * @return string|null
 781          */
 782         protected function getQueryVerb( $sql ) {
 783                 return preg_match( '/^\s*([a-z]+)/i', $sql, $m ) ? strtoupper( $m[1] ) : null;
 784         }
 785
 786         /**
 787          * Determine whether a SQL statement is sensitive to isolation level.
 788          * A SQL statement is considered transactable if its result could vary
 789          * depending on the transaction isolation level. Operational commands
 790          * such as 'SET' and 'SHOW' are not considered to be transactable.
 791          *
 792          * @param string $sql
 793          * @return bool
 794          */
 795         protected function isTransactableQuery( $sql ) {
 796                 return !in_array(
 797                         $this->getQueryVerb( $sql ),
 798                         [ 'BEGIN', 'COMMIT', 'ROLLBACK', 'SHOW', 'SET', 'CREATE', 'ALTER' ],
 799                         true
 800                 );
 801         }
 802
 803         /**
 804          * @param string $sql A SQL query
 805          * @return bool Whether $sql is SQL for creating/dropping a new TEMPORARY table
 806          */
 807         protected function registerTempTableOperation( $sql ) {
 808                 if ( preg_match(
 809                         '/^CREATE\s+TEMPORARY\s+TABLE\s+(?:IF\s+NOT\s+EXISTS\s+)?[`"\']?(\w+)[`"\']?/i',
 810                         $sql,
 811                         $matches
 812                 ) ) {
 813                         $this->mSessionTempTables[$matches[1]] = 1;
 814
 815                         return true;
 816                 } elseif ( preg_match(
 817                         '/^DROP\s+(?:TEMPORARY\s+)?TABLE\s+(?:IF\s+EXISTS\s+)?[`"\']?(\w+)[`"\']?/i',
 818                         $sql,
 819                         $matches
 820                 ) ) {
 821                         unset( $this->mSessionTempTables[$matches[1]] );
 822
 823                         return true;
 824                 } elseif ( preg_match(
 825                         '/^(?:INSERT\s+(?:\w+\s+)?INTO|UPDATE|DELETE\s+FROM)\s+[`"\']?(\w+)[`"\']?/i',
 826                         $sql,
 827                         $matches
 828                 ) ) {
 829                         return isset( $this->mSessionTempTables[$matches[1]] );
 830                 }
 831
 832                 return false;
 833         }
 834
 835         public function query( $sql, $fname = __METHOD__, $tempIgnore = false ) {
 836                 $priorWritesPending = $this->writesOrCallbacksPending();
 837                 $this->mLastQuery = $sql;
 838
 839                 $isWrite = $this->isWriteQuery( $sql ) && !$this->registerTempTableOperation( $sql );
 840                 if ( $isWrite ) {
 841                         $reason = $this->getReadOnlyReason();
 842                         if ( $reason !== false ) {
 843                                 throw new DBReadOnlyError( $this, "Database is read-only: $reason" );
 844                         }
 845                         # Set a flag indicating that writes have been done
 846                         $this->mLastWriteTime = microtime( true );
 847                 }
 848
 849                 // Add trace comment to the begin of the sql string, right after the operator.
 850                 // Or, for one-word queries (like "BEGIN" or COMMIT") add it to the end (T44598)
 851                 $commentedSql = preg_replace( '/\s|$/', " /* $fname {$this->agent} */ ", $sql, 1 );
 852
 853                 # Start implicit transactions that wrap the request if DBO_TRX is enabled
 854                 if ( !$this->mTrxLevel && $this->getFlag( self::DBO_TRX )
 855                         && $this->isTransactableQuery( $sql )
 856                 ) {
 857                         $this->begin( __METHOD__ . " ($fname)", self::TRANSACTION_INTERNAL );
 858                         $this->mTrxAutomatic = true;
 859                 }
 860
 861                 # Keep track of whether the transaction has write queries pending
 862                 if ( $this->mTrxLevel && !$this->mTrxDoneWrites && $isWrite ) {
 863                         $this->mTrxDoneWrites = true;
 864                         $this->trxProfiler->transactionWritingIn(
 865                                 $this->mServer, $this->mDBname, $this->mTrxShortId );
 866                 }
 867
 868                 if ( $this->getFlag( self::DBO_DEBUG ) ) {
 869                         $this->queryLogger->debug( "{$this->mDBname} {$commentedSql}" );
 870                 }
 871
 872                 # Avoid fatals if close() was called
 873                 $this->assertOpen();
 874
 875                 # Send the query to the server
 876                 $ret = $this->doProfiledQuery( $sql, $commentedSql, $isWrite, $fname );
 877
 878                 # Try reconnecting if the connection was lost
 879                 if ( false === $ret && $this->wasErrorReissuable() ) {
 880                         $recoverable = $this->canRecoverFromDisconnect( $sql, $priorWritesPending );
 881                         # Stash the last error values before anything might clear them
 882                         $lastError = $this->lastError();
 883                         $lastErrno = $this->lastErrno();
 884                         # Update state tracking to reflect transaction loss due to disconnection
 885                         $this->handleSessionLoss();
 886                         if ( $this->reconnect() ) {
 887                                 $msg = __METHOD__ . ": lost connection to {$this->getServer()}; reconnected";
 888                                 $this->connLogger->warning( $msg );
 889                                 $this->queryLogger->warning(
 890                                         "$msg:\n" . ( new RuntimeException() )->getTraceAsString() );
 891
 892                                 if ( !$recoverable ) {
 893                                         # Callers may catch the exception and continue to use the DB
 894                                         $this->reportQueryError( $lastError, $lastErrno, $sql, $fname );
 895                                 } else {
 896                                         # Should be safe to silently retry the query
 897                                         $ret = $this->doProfiledQuery( $sql, $commentedSql, $isWrite, $fname );
 898                                 }
 899                         } else {
 900                                 $msg = __METHOD__ . ": lost connection to {$this->getServer()} permanently";
 901                                 $this->connLogger->error( $msg );
 902                         }
 903                 }
 904
 905                 if ( false === $ret ) {
 906                         # Deadlocks cause the entire transaction to abort, not just the statement.
 907                         # https://dev.mysql.com/doc/refman/5.7/en/innodb-error-handling.html
 908                         # https://www.postgresql.org/docs/9.1/static/explicit-locking.html
 909                         if ( $this->wasDeadlock() ) {
 910                                 if ( $this->explicitTrxActive() || $priorWritesPending ) {
 911                                         $tempIgnore = false; // not recoverable
 912                                 }
 913                                 # Update state tracking to reflect transaction loss
 914                                 $this->handleSessionLoss();
 915                         }
 916
 917                         $this->reportQueryError(
 918                                 $this->lastError(), $this->lastErrno(), $sql, $fname, $tempIgnore );
 919                 }
 920
 921                 $res = $this->resultObject( $ret );
 922
 923                 return $res;
 924         }
 925
 926         private function doProfiledQuery( $sql, $commentedSql, $isWrite, $fname ) {
 927                 $isMaster = !is_null( $this->getLBInfo( 'master' ) );
 928                 # generalizeSQL() will probably cut down the query to reasonable
 929                 # logging size most of the time. The substr is really just a sanity check.
 930                 if ( $isMaster ) {
 931                         $queryProf = 'query-m: ' . substr( self::generalizeSQL( $sql ), 0, 255 );
 932                 } else {
 933                         $queryProf = 'query: ' . substr( self::generalizeSQL( $sql ), 0, 255 );
 934                 }
 935
 936                 # Include query transaction state
 937                 $queryProf .= $this->mTrxShortId ? " [TRX#{$this->mTrxShortId}]" : "";
 938
 939                 $startTime = microtime( true );
 940                 if ( $this->profiler ) {
 941                         call_user_func( [ $this->profiler, 'profileIn' ], $queryProf );
 942                 }
 943                 $ret = $this->doQuery( $commentedSql );
 944                 if ( $this->profiler ) {
 945                         call_user_func( [ $this->profiler, 'profileOut' ], $queryProf );
 946                 }
 947                 $queryRuntime = max( microtime( true ) - $startTime, 0.0 );
 948
 949                 unset( $queryProfSection ); // profile out (if set)
 950
 951                 if ( $ret !== false ) {
 952                         $this->lastPing = $startTime;
 953                         if ( $isWrite && $this->mTrxLevel ) {
 954                                 $this->updateTrxWriteQueryTime( $sql, $queryRuntime );
 955                                 $this->mTrxWriteCallers[] = $fname;
 956                         }
 957                 }
 958
 959                 if ( $sql === self::PING_QUERY ) {
 960                         $this->mRTTEstimate = $queryRuntime;
 961                 }
 962
 963                 $this->trxProfiler->recordQueryCompletion(
 964                         $queryProf, $startTime, $isWrite, $this->affectedRows()
 965                 );
 966                 $this->queryLogger->debug( $sql, [
 967                         'method' => $fname,
 968                         'master' => $isMaster,
 969                         'runtime' => $queryRuntime,
 970                 ] );
 971
 972                 return $ret;
 973         }
 974
 975         /**
 976          * Update the estimated run-time of a query, not counting large row lock times
 977          *
 978          * LoadBalancer can be set to rollback transactions that will create huge replication
 979          * lag. It bases this estimate off of pendingWriteQueryDuration(). Certain simple
 980          * queries, like inserting a row can take a long time due to row locking. This method
 981          * uses some simple heuristics to discount those cases.
 982          *
 983          * @param string $sql A SQL write query
 984          * @param float $runtime Total runtime, including RTT
 985          */
 986         private function updateTrxWriteQueryTime( $sql, $runtime ) {
 987                 // Whether this is indicative of replica DB runtime (except for RBR or ws_repl)
 988                 $indicativeOfReplicaRuntime = true;
 989                 if ( $runtime > self::SLOW_WRITE_SEC ) {
 990                         $verb = $this->getQueryVerb( $sql );
 991                         // insert(), upsert(), replace() are fast unless bulky in size or blocked on locks
 992                         if ( $verb === 'INSERT' ) {
 993                                 $indicativeOfReplicaRuntime = $this->affectedRows() > self::SMALL_WRITE_ROWS;
 994                         } elseif ( $verb === 'REPLACE' ) {
 995                                 $indicativeOfReplicaRuntime = $this->affectedRows() > self::SMALL_WRITE_ROWS / 2;
 996                         }
 997                 }
 998
 999                 $this->mTrxWriteDuration += $runtime;
1000                 $this->mTrxWriteQueryCount += 1;
1001                 if ( $indicativeOfReplicaRuntime ) {
1002                         $this->mTrxWriteAdjDuration += $runtime;
1003                         $this->mTrxWriteAdjQueryCount += 1;
1004                 }
1005         }
1006
1007         private function canRecoverFromDisconnect( $sql, $priorWritesPending ) {
1008                 # Transaction dropped; this can mean lost writes, or REPEATABLE-READ snapshots.
1009                 # Dropped connections also mean that named locks are automatically released.
1010                 # Only allow error suppression in autocommit mode or when the lost transaction
1011                 # didn't matter anyway (aside from DBO_TRX snapshot loss).
1012                 if ( $this->mNamedLocksHeld ) {
1013                         return false; // possible critical section violation
1014                 } elseif ( $sql === 'COMMIT' ) {
1015                         return !$priorWritesPending; // nothing written anyway? (T127428)
1016                 } elseif ( $sql === 'ROLLBACK' ) {
1017                         return true; // transaction lost...which is also what was requested :)
1018                 } elseif ( $this->explicitTrxActive() ) {
1019                         return false; // don't drop atomocity
1020                 } elseif ( $priorWritesPending ) {
1021                         return false; // prior writes lost from implicit transaction
1022                 }
1023
1024                 return true;
1025         }
1026
1027         private function handleSessionLoss() {
1028                 $this->mTrxLevel = 0;
1029                 $this->mTrxIdleCallbacks = []; // T67263
1030                 $this->mTrxPreCommitCallbacks = []; // T67263
1031                 $this->mSessionTempTables = [];
1032                 $this->mNamedLocksHeld = [];
1033                 try {
1034                         // Handle callbacks in mTrxEndCallbacks
1035                         $this->runOnTransactionIdleCallbacks( self::TRIGGER_ROLLBACK );
1036                         $this->runTransactionListenerCallbacks( self::TRIGGER_ROLLBACK );
1037                         return null;
1038                 } catch ( Exception $e ) {
1039                         // Already logged; move on...
1040                         return $e;
1041                 }
1042         }
1043
1044         public function reportQueryError( $error, $errno, $sql, $fname, $tempIgnore = false ) {
1045                 if ( $this->ignoreErrors() || $tempIgnore ) {
1046                         $this->queryLogger->debug( "SQL ERROR (ignored): $error\n" );
1047                 } else {
1048                         $sql1line = mb_substr( str_replace( "\n", "\\n", $sql ), 0, 5 * 1024 );
1049                         $this->queryLogger->error(
1050                                 "{fname}\t{db_server}\t{errno}\t{error}\t{sql1line}",
1051                                 $this->getLogContext( [
1052                                         'method' => __METHOD__,
1053                                         'errno' => $errno,
1054                                         'error' => $error,
1055                                         'sql1line' => $sql1line,
1056                                         'fname' => $fname,
1057                                 ] )
1058                         );
1059                         $this->queryLogger->debug( "SQL ERROR: " . $error . "\n" );
1060                         throw new DBQueryError( $this, $error, $errno, $sql, $fname );
1061                 }
1062         }
1063
1064         public function freeResult( $res ) {
1065         }
1066
1067         public function selectField(
1068                 $table, $var, $cond = '', $fname = __METHOD__, $options = []
1069         ) {
1070                 if ( $var === '*' ) { // sanity
1071                         throw new DBUnexpectedError( $this, "Cannot use a * field: got '$var'" );
1072                 }
1073
1074                 if ( !is_array( $options ) ) {
1075                         $options = [ $options ];
1076                 }
1077
1078                 $options['LIMIT'] = 1;
1079
1080                 $res = $this->select( $table, $var, $cond, $fname, $options );
1081                 if ( $res === false || !$this->numRows( $res ) ) {
1082                         return false;
1083                 }
1084
1085                 $row = $this->fetchRow( $res );
1086
1087                 if ( $row !== false ) {
1088                         return reset( $row );
1089                 } else {
1090                         return false;
1091                 }
1092         }
1093
1094         public function selectFieldValues(
1095                 $table, $var, $cond = '', $fname = __METHOD__, $options = [], $join_conds = []
1096         ) {
1097                 if ( $var === '*' ) { // sanity
1098                         throw new DBUnexpectedError( $this, "Cannot use a * field" );
1099                 } elseif ( !is_string( $var ) ) { // sanity
1100                         throw new DBUnexpectedError( $this, "Cannot use an array of fields" );
1101                 }
1102
1103                 if ( !is_array( $options ) ) {
1104                         $options = [ $options ];
1105                 }
1106
1107                 $res = $this->select( $table, $var, $cond, $fname, $options, $join_conds );
1108                 if ( $res === false ) {
1109                         return false;
1110                 }
1111
1112                 $values = [];
1113                 foreach ( $res as $row ) {
1114                         $values[] = $row->$var;
1115                 }
1116
1117                 return $values;
1118         }
1119
1120         /**
1121          * Returns an optional USE INDEX clause to go after the table, and a
1122          * string to go at the end of the query.
1123          *
1124          * @param array $options Associative array of options to be turned into
1125          *   an SQL query, valid keys are listed in the function.
1126          * @return array
1127          * @see Database::select()
1128          */
1129         protected function makeSelectOptions( $options ) {
1130                 $preLimitTail = $postLimitTail = '';
1131                 $startOpts = '';
1132
1133                 $noKeyOptions = [];
1134
1135                 foreach ( $options as $key => $option ) {
1136                         if ( is_numeric( $key ) ) {
1137                                 $noKeyOptions[$option] = true;
1138                         }
1139                 }
1140
1141                 $preLimitTail .= $this->makeGroupByWithHaving( $options );
1142
1143                 $preLimitTail .= $this->makeOrderBy( $options );
1144
1145                 if ( isset( $noKeyOptions['FOR UPDATE'] ) ) {
1146                         $postLimitTail .= ' FOR UPDATE';
1147                 }
1148
1149                 if ( isset( $noKeyOptions['LOCK IN SHARE MODE'] ) ) {
1150                         $postLimitTail .= ' LOCK IN SHARE MODE';
1151                 }
1152
1153                 if ( isset( $noKeyOptions['DISTINCT'] ) || isset( $noKeyOptions['DISTINCTROW'] ) ) {
1154                         $startOpts .= 'DISTINCT';
1155                 }
1156
1157                 # Various MySQL extensions
1158                 if ( isset( $noKeyOptions['STRAIGHT_JOIN'] ) ) {
1159                         $startOpts .= ' /*! STRAIGHT_JOIN */';
1160                 }
1161
1162                 if ( isset( $noKeyOptions['HIGH_PRIORITY'] ) ) {
1163                         $startOpts .= ' HIGH_PRIORITY';
1164                 }
1165
1166                 if ( isset( $noKeyOptions['SQL_BIG_RESULT'] ) ) {
1167                         $startOpts .= ' SQL_BIG_RESULT';
1168                 }
1169
1170                 if ( isset( $noKeyOptions['SQL_BUFFER_RESULT'] ) ) {
1171                         $startOpts .= ' SQL_BUFFER_RESULT';
1172                 }
1173
1174                 if ( isset( $noKeyOptions['SQL_SMALL_RESULT'] ) ) {
1175                         $startOpts .= ' SQL_SMALL_RESULT';
1176                 }
1177
1178                 if ( isset( $noKeyOptions['SQL_CALC_FOUND_ROWS'] ) ) {
1179                         $startOpts .= ' SQL_CALC_FOUND_ROWS';
1180                 }
1181
1182                 if ( isset( $noKeyOptions['SQL_CACHE'] ) ) {
1183                         $startOpts .= ' SQL_CACHE';
1184                 }
1185
1186                 if ( isset( $noKeyOptions['SQL_NO_CACHE'] ) ) {
1187                         $startOpts .= ' SQL_NO_CACHE';
1188                 }
1189
1190                 if ( isset( $options['USE INDEX'] ) && is_string( $options['USE INDEX'] ) ) {
1191                         $useIndex = $this->useIndexClause( $options['USE INDEX'] );
1192                 } else {
1193                         $useIndex = '';
1194                 }
1195                 if ( isset( $options['IGNORE INDEX'] ) && is_string( $options['IGNORE INDEX'] ) ) {
1196                         $ignoreIndex = $this->ignoreIndexClause( $options['IGNORE INDEX'] );
1197                 } else {
1198                         $ignoreIndex = '';
1199                 }
1200
1201                 return [ $startOpts, $useIndex, $preLimitTail, $postLimitTail, $ignoreIndex ];
1202         }
1203
1204         /**
1205          * Returns an optional GROUP BY with an optional HAVING
1206          *
1207          * @param array $options Associative array of options
1208          * @return string
1209          * @see Database::select()
1210          * @since 1.21
1211          */
1212         protected function makeGroupByWithHaving( $options ) {
1213                 $sql = '';
1214                 if ( isset( $options['GROUP BY'] ) ) {
1215                         $gb = is_array( $options['GROUP BY'] )
1216                                 ? implode( ',', $options['GROUP BY'] )
1217                                 : $options['GROUP BY'];
1218                         $sql .= ' GROUP BY ' . $gb;
1219                 }
1220                 if ( isset( $options['HAVING'] ) ) {
1221                         $having = is_array( $options['HAVING'] )
1222                                 ? $this->makeList( $options['HAVING'], self::LIST_AND )
1223                                 : $options['HAVING'];
1224                         $sql .= ' HAVING ' . $having;
1225                 }
1226
1227                 return $sql;
1228         }
1229
1230         /**
1231          * Returns an optional ORDER BY
1232          *
1233          * @param array $options Associative array of options
1234          * @return string
1235          * @see Database::select()
1236          * @since 1.21
1237          */
1238         protected function makeOrderBy( $options ) {
1239                 if ( isset( $options['ORDER BY'] ) ) {
1240                         $ob = is_array( $options['ORDER BY'] )
1241                                 ? implode( ',', $options['ORDER BY'] )
1242                                 : $options['ORDER BY'];
1243
1244                         return ' ORDER BY ' . $ob;
1245                 }
1246
1247                 return '';
1248         }
1249
1250         public function select( $table, $vars, $conds = '', $fname = __METHOD__,
1251                 $options = [], $join_conds = [] ) {
1252                 $sql = $this->selectSQLText( $table, $vars, $conds, $fname, $options, $join_conds );
1253
1254                 return $this->query( $sql, $fname );
1255         }
1256
1257         public function selectSQLText( $table, $vars, $conds = '', $fname = __METHOD__,
1258                 $options = [], $join_conds = []
1259         ) {
1260                 if ( is_array( $vars ) ) {
1261                         $vars = implode( ',', $this->fieldNamesWithAlias( $vars ) );
1262                 }
1263
1264                 $options = (array)$options;
1265                 $useIndexes = ( isset( $options['USE INDEX'] ) && is_array( $options['USE INDEX'] ) )
1266                         ? $options['USE INDEX']
1267                         : [];
1268                 $ignoreIndexes = (
1269                         isset( $options['IGNORE INDEX'] ) &&
1270                         is_array( $options['IGNORE INDEX'] )
1271                 )
1272                         ? $options['IGNORE INDEX']
1273                         : [];
1274
1275                 if ( is_array( $table ) ) {
1276                         $from = ' FROM ' .
1277                                 $this->tableNamesWithIndexClauseOrJOIN(
1278                                         $table, $useIndexes, $ignoreIndexes, $join_conds );
1279                 } elseif ( $table != '' ) {
1280                         if ( $table[0] == ' ' ) {
1281                                 $from = ' FROM ' . $table;
1282                         } else {
1283                                 $from = ' FROM ' .
1284                                         $this->tableNamesWithIndexClauseOrJOIN(
1285                                                 [ $table ], $useIndexes, $ignoreIndexes, [] );
1286                         }
1287                 } else {
1288                         $from = '';
1289                 }
1290
1291                 list( $startOpts, $useIndex, $preLimitTail, $postLimitTail, $ignoreIndex ) =
1292                         $this->makeSelectOptions( $options );
1293
1294                 if ( !empty( $conds ) ) {
1295                         if ( is_array( $conds ) ) {
1296                                 $conds = $this->makeList( $conds, self::LIST_AND );
1297                         }
1298                         $sql = "SELECT $startOpts $vars $from $useIndex $ignoreIndex " .
1299                                 "WHERE $conds $preLimitTail";
1300                 } else {
1301                         $sql = "SELECT $startOpts $vars $from $useIndex $ignoreIndex $preLimitTail";
1302                 }
1303
1304                 if ( isset( $options['LIMIT'] ) ) {
1305                         $sql = $this->limitResult( $sql, $options['LIMIT'],
1306                                 isset( $options['OFFSET'] ) ? $options['OFFSET'] : false );
1307                 }
1308                 $sql = "$sql $postLimitTail";
1309
1310                 if ( isset( $options['EXPLAIN'] ) ) {
1311                         $sql = 'EXPLAIN ' . $sql;
1312                 }
1313
1314                 return $sql;
1315         }
1316
1317         public function selectRow( $table, $vars, $conds, $fname = __METHOD__,
1318                 $options = [], $join_conds = []
1319         ) {
1320                 $options = (array)$options;
1321                 $options['LIMIT'] = 1;
1322                 $res = $this->select( $table, $vars, $conds, $fname, $options, $join_conds );
1323
1324                 if ( $res === false ) {
1325                         return false;
1326                 }
1327
1328                 if ( !$this->numRows( $res ) ) {
1329                         return false;
1330                 }
1331
1332                 $obj = $this->fetchObject( $res );
1333
1334                 return $obj;
1335         }
1336
1337         public function estimateRowCount(
1338                 $table, $vars = '*', $conds = '', $fname = __METHOD__, $options = []
1339         ) {
1340                 $rows = 0;
1341                 $res = $this->select( $table, [ 'rowcount' => 'COUNT(*)' ], $conds, $fname, $options );
1342
1343                 if ( $res ) {
1344                         $row = $this->fetchRow( $res );
1345                         $rows = ( isset( $row['rowcount'] ) ) ? (int)$row['rowcount'] : 0;
1346                 }
1347
1348                 return $rows;
1349         }
1350
1351         public function selectRowCount(
1352                 $tables, $vars = '*', $conds = '', $fname = __METHOD__, $options = [], $join_conds = []
1353         ) {
1354                 $rows = 0;
1355                 $sql = $this->selectSQLText( $tables, '1', $conds, $fname, $options, $join_conds );
1356                 $res = $this->query( "SELECT COUNT(*) AS rowcount FROM ($sql) tmp_count", $fname );
1357
1358                 if ( $res ) {
1359                         $row = $this->fetchRow( $res );
1360                         $rows = ( isset( $row['rowcount'] ) ) ? (int)$row['rowcount'] : 0;
1361                 }
1362
1363                 return $rows;
1364         }
1365
1366         /**
1367          * Removes most variables from an SQL query and replaces them with X or N for numbers.
1368          * It's only slightly flawed. Don't use for anything important.
1369          *
1370          * @param string $sql A SQL Query
1371          *
1372          * @return string
1373          */
1374         protected static function generalizeSQL( $sql ) {
1375                 # This does the same as the regexp below would do, but in such a way
1376                 # as to avoid crashing php on some large strings.
1377                 # $sql = preg_replace( "/'([^\\\\']|\\\\.)*'|\"([^\\\\\"]|\\\\.)*\"/", "'X'", $sql );
1378
1379                 $sql = str_replace( "\\\\", '', $sql );
1380                 $sql = str_replace( "\\'", '', $sql );
1381                 $sql = str_replace( "\\\"", '', $sql );
1382                 $sql = preg_replace( "/'.*'/s", "'X'", $sql );
1383                 $sql = preg_replace( '/".*"/s', "'X'", $sql );
1384
1385                 # All newlines, tabs, etc replaced by single space
1386                 $sql = preg_replace( '/\s+/', ' ', $sql );
1387
1388                 # All numbers => N,
1389                 # except the ones surrounded by characters, e.g. l10n
1390                 $sql = preg_replace( '/-?\d+(,-?\d+)+/s', 'N,...,N', $sql );
1391                 $sql = preg_replace( '/(?<![a-zA-Z])-?\d+(?![a-zA-Z])/s', 'N', $sql );
1392
1393                 return $sql;
1394         }
1395
1396         public function fieldExists( $table, $field, $fname = __METHOD__ ) {
1397                 $info = $this->fieldInfo( $table, $field );
1398
1399                 return (bool)$info;
1400         }
1401
1402         public function indexExists( $table, $index, $fname = __METHOD__ ) {
1403                 if ( !$this->tableExists( $table ) ) {
1404                         return null;
1405                 }
1406
1407                 $info = $this->indexInfo( $table, $index, $fname );
1408                 if ( is_null( $info ) ) {
1409                         return null;
1410                 } else {
1411                         return $info !== false;
1412                 }
1413         }
1414
1415         public function tableExists( $table, $fname = __METHOD__ ) {
1416                 $tableRaw = $this->tableName( $table, 'raw' );
1417                 if ( isset( $this->mSessionTempTables[$tableRaw] ) ) {
1418                         return true; // already known to exist
1419                 }
1420
1421                 $table = $this->tableName( $table );
1422                 $ignoreErrors = true;
1423                 $res = $this->query( "SELECT 1 FROM $table LIMIT 1", $fname, $ignoreErrors );
1424
1425                 return (bool)$res;
1426         }
1427
1428         public function indexUnique( $table, $index ) {
1429                 $indexInfo = $this->indexInfo( $table, $index );
1430
1431                 if ( !$indexInfo ) {
1432                         return null;
1433                 }
1434
1435                 return !$indexInfo[0]->Non_unique;
1436         }
1437
1438         /**
1439          * Helper for Database::insert().
1440          *
1441          * @param array $options
1442          * @return string
1443          */
1444         protected function makeInsertOptions( $options ) {
1445                 return implode( ' ', $options );
1446         }
1447
1448         public function insert( $table, $a, $fname = __METHOD__, $options = [] ) {
1449                 # No rows to insert, easy just return now
1450                 if ( !count( $a ) ) {
1451                         return true;
1452                 }
1453
1454                 $table = $this->tableName( $table );
1455
1456                 if ( !is_array( $options ) ) {
1457                         $options = [ $options ];
1458                 }
1459
1460                 $fh = null;
1461                 if ( isset( $options['fileHandle'] ) ) {
1462                         $fh = $options['fileHandle'];
1463                 }
1464                 $options = $this->makeInsertOptions( $options );
1465
1466                 if ( isset( $a[0] ) && is_array( $a[0] ) ) {
1467                         $multi = true;
1468                         $keys = array_keys( $a[0] );
1469                 } else {
1470                         $multi = false;
1471                         $keys = array_keys( $a );
1472                 }
1473
1474                 $sql = 'INSERT ' . $options .
1475                         " INTO $table (" . implode( ',', $keys ) . ') VALUES ';
1476
1477                 if ( $multi ) {
1478                         $first = true;
1479                         foreach ( $a as $row ) {
1480                                 if ( $first ) {
1481                                         $first = false;
1482                                 } else {
1483                                         $sql .= ',';
1484                                 }
1485                                 $sql .= '(' . $this->makeList( $row ) . ')';
1486                         }
1487                 } else {
1488                         $sql .= '(' . $this->makeList( $a ) . ')';
1489                 }
1490
1491                 if ( $fh !== null && false === fwrite( $fh, $sql ) ) {
1492                         return false;
1493                 } elseif ( $fh !== null ) {
1494                         return true;
1495                 }
1496
1497                 return (bool)$this->query( $sql, $fname );
1498         }
1499
1500         /**
1501          * Make UPDATE options array for Database::makeUpdateOptions
1502          *
1503          * @param array $options
1504          * @return array
1505          */
1506         protected function makeUpdateOptionsArray( $options ) {
1507                 if ( !is_array( $options ) ) {
1508                         $options = [ $options ];
1509                 }
1510
1511                 $opts = [];
1512
1513                 if ( in_array( 'IGNORE', $options ) ) {
1514                         $opts[] = 'IGNORE';
1515                 }
1516
1517                 return $opts;
1518         }
1519
1520         /**
1521          * Make UPDATE options for the Database::update function
1522          *
1523          * @param array $options The options passed to Database::update
1524          * @return string
1525          */
1526         protected function makeUpdateOptions( $options ) {
1527                 $opts = $this->makeUpdateOptionsArray( $options );
1528
1529                 return implode( ' ', $opts );
1530         }
1531
1532         public function update( $table, $values, $conds, $fname = __METHOD__, $options = [] ) {
1533                 $table = $this->tableName( $table );
1534                 $opts = $this->makeUpdateOptions( $options );
1535                 $sql = "UPDATE $opts $table SET " . $this->makeList( $values, self::LIST_SET );
1536
1537                 if ( $conds !== [] && $conds !== '*' ) {
1538                         $sql .= " WHERE " . $this->makeList( $conds, self::LIST_AND );
1539                 }
1540
1541                 return $this->query( $sql, $fname );
1542         }
1543
1544         public function makeList( $a, $mode = self::LIST_COMMA ) {
1545                 if ( !is_array( $a ) ) {
1546                         throw new DBUnexpectedError( $this, __METHOD__ . ' called with incorrect parameters' );
1547                 }
1548
1549                 $first = true;
1550                 $list = '';
1551
1552                 foreach ( $a as $field => $value ) {
1553                         if ( !$first ) {
1554                                 if ( $mode == self::LIST_AND ) {
1555                                         $list .= ' AND ';
1556                                 } elseif ( $mode == self::LIST_OR ) {
1557                                         $list .= ' OR ';
1558                                 } else {
1559                                         $list .= ',';
1560                                 }
1561                         } else {
1562                                 $first = false;
1563                         }
1564
1565                         if ( ( $mode == self::LIST_AND || $mode == self::LIST_OR ) && is_numeric( $field ) ) {
1566                                 $list .= "($value)";
1567                         } elseif ( $mode == self::LIST_SET && is_numeric( $field ) ) {
1568                                 $list .= "$value";
1569                         } elseif (
1570                                 ( $mode == self::LIST_AND || $mode == self::LIST_OR ) && is_array( $value )
1571                         ) {
1572                                 // Remove null from array to be handled separately if found
1573                                 $includeNull = false;
1574                                 foreach ( array_keys( $value, null, true ) as $nullKey ) {
1575                                         $includeNull = true;
1576                                         unset( $value[$nullKey] );
1577                                 }
1578                                 if ( count( $value ) == 0 && !$includeNull ) {
1579                                         throw new InvalidArgumentException(
1580                                                 __METHOD__ . ": empty input for field $field" );
1581                                 } elseif ( count( $value ) == 0 ) {
1582                                         // only check if $field is null
1583                                         $list .= "$field IS NULL";
1584                                 } else {
1585                                         // IN clause contains at least one valid element
1586                                         if ( $includeNull ) {
1587                                                 // Group subconditions to ensure correct precedence
1588                                                 $list .= '(';
1589                                         }
1590                                         if ( count( $value ) == 1 ) {
1591                                                 // Special-case single values, as IN isn't terribly efficient
1592                                                 // Don't necessarily assume the single key is 0; we don't
1593                                                 // enforce linear numeric ordering on other arrays here.
1594                                                 $value = array_values( $value )[0];
1595                                                 $list .= $field . " = " . $this->addQuotes( $value );
1596                                         } else {
1597                                                 $list .= $field . " IN (" . $this->makeList( $value ) . ") ";
1598                                         }
1599                                         // if null present in array, append IS NULL
1600                                         if ( $includeNull ) {
1601                                                 $list .= " OR $field IS NULL)";
1602                                         }
1603                                 }
1604                         } elseif ( $value === null ) {
1605                                 if ( $mode == self::LIST_AND || $mode == self::LIST_OR ) {
1606                                         $list .= "$field IS ";
1607                                 } elseif ( $mode == self::LIST_SET ) {
1608                                         $list .= "$field = ";
1609                                 }
1610                                 $list .= 'NULL';
1611                         } else {
1612                                 if (
1613                                         $mode == self::LIST_AND || $mode == self::LIST_OR || $mode == self::LIST_SET
1614                                 ) {
1615                                         $list .= "$field = ";
1616                                 }
1617                                 $list .= $mode == self::LIST_NAMES ? $value : $this->addQuotes( $value );
1618                         }
1619                 }
1620
1621                 return $list;
1622         }
1623
1624         public function makeWhereFrom2d( $data, $baseKey, $subKey ) {
1625                 $conds = [];
1626
1627                 foreach ( $data as $base => $sub ) {
1628                         if ( count( $sub ) ) {
1629                                 $conds[] = $this->makeList(
1630                                         [ $baseKey => $base, $subKey => array_keys( $sub ) ],
1631                                         self::LIST_AND );
1632                         }
1633                 }
1634
1635                 if ( $conds ) {
1636                         return $this->makeList( $conds, self::LIST_OR );
1637                 } else {
1638                         // Nothing to search for...
1639                         return false;
1640                 }
1641         }
1642
1643         public function aggregateValue( $valuedata, $valuename = 'value' ) {
1644                 return $valuename;
1645         }
1646
1647         public function bitNot( $field ) {
1648                 return "(~$field)";
1649         }
1650
1651         public function bitAnd( $fieldLeft, $fieldRight ) {
1652                 return "($fieldLeft & $fieldRight)";
1653         }
1654
1655         public function bitOr( $fieldLeft, $fieldRight ) {
1656                 return "($fieldLeft | $fieldRight)";
1657         }
1658
1659         public function buildConcat( $stringList ) {
1660                 return 'CONCAT(' . implode( ',', $stringList ) . ')';
1661         }
1662
1663         public function buildGroupConcatField(
1664                 $delim, $table, $field, $conds = '', $join_conds = []
1665         ) {
1666                 $fld = "GROUP_CONCAT($field SEPARATOR " . $this->addQuotes( $delim ) . ')';
1667
1668                 return '(' . $this->selectSQLText( $table, $fld, $conds, null, [], $join_conds ) . ')';
1669         }
1670
1671         public function buildStringCast( $field ) {
1672                 return $field;
1673         }
1674
1675         public function selectDB( $db ) {
1676                 # Stub. Shouldn't cause serious problems if it's not overridden, but
1677                 # if your database engine supports a concept similar to MySQL's
1678                 # databases you may as well.
1679                 $this->mDBname = $db;
1680
1681                 return true;
1682         }
1683
1684         public function getDBname() {
1685                 return $this->mDBname;
1686         }
1687
1688         public function getServer() {
1689                 return $this->mServer;
1690         }
1691
1692         public function tableName( $name, $format = 'quoted' ) {
1693                 # Skip the entire process when we have a string quoted on both ends.
1694                 # Note that we check the end so that we will still quote any use of
1695                 # use of `database`.table. But won't break things if someone wants
1696                 # to query a database table with a dot in the name.
1697                 if ( $this->isQuotedIdentifier( $name ) ) {
1698                         return $name;
1699                 }
1700
1701                 # Lets test for any bits of text that should never show up in a table
1702                 # name. Basically anything like JOIN or ON which are actually part of
1703                 # SQL queries, but may end up inside of the table value to combine
1704                 # sql. Such as how the API is doing.
1705                 # Note that we use a whitespace test rather than a \b test to avoid
1706                 # any remote case where a word like on may be inside of a table name
1707                 # surrounded by symbols which may be considered word breaks.
1708                 if ( preg_match( '/(^|\s)(DISTINCT|JOIN|ON|AS)(\s|$)/i', $name ) !== 0 ) {
1709                         return $name;
1710                 }
1711
1712                 # Split database and table into proper variables.
1713                 # We reverse the explode so that database.table and table both output
1714                 # the correct table.
1715                 $dbDetails = explode( '.', $name, 3 );
1716                 if ( count( $dbDetails ) == 3 ) {
1717                         list( $database, $schema, $table ) = $dbDetails;
1718                         # We don't want any prefix added in this case
1719                         $prefix = '';
1720                 } elseif ( count( $dbDetails ) == 2 ) {
1721                         list( $database, $table ) = $dbDetails;
1722                         # We don't want any prefix added in this case
1723                         $prefix = '';
1724                         # In dbs that support it, $database may actually be the schema
1725                         # but that doesn't affect any of the functionality here
1726                         $schema = '';
1727                 } else {
1728                         list( $table ) = $dbDetails;
1729                         if ( isset( $this->tableAliases[$table] ) ) {
1730                                 $database = $this->tableAliases[$table]['dbname'];
1731                                 $schema = is_string( $this->tableAliases[$table]['schema'] )
1732                                         ? $this->tableAliases[$table]['schema']
1733                                         : $this->mSchema;
1734                                 $prefix = is_string( $this->tableAliases[$table]['prefix'] )
1735                                         ? $this->tableAliases[$table]['prefix']
1736                                         : $this->mTablePrefix;
1737                         } else {
1738                                 $database = '';
1739                                 $schema = $this->mSchema; # Default schema
1740                                 $prefix = $this->mTablePrefix; # Default prefix
1741                         }
1742                 }
1743
1744                 # Quote $table and apply the prefix if not quoted.
1745                 # $tableName might be empty if this is called from Database::replaceVars()
1746                 $tableName = "{$prefix}{$table}";
1747                 if ( $format === 'quoted'
1748                         && !$this->isQuotedIdentifier( $tableName )
1749                         && $tableName !== ''
1750                 ) {
1751                         $tableName = $this->addIdentifierQuotes( $tableName );
1752                 }
1753
1754                 # Quote $schema and $database and merge them with the table name if needed
1755                 $tableName = $this->prependDatabaseOrSchema( $schema, $tableName, $format );
1756                 $tableName = $this->prependDatabaseOrSchema( $database, $tableName, $format );
1757
1758                 return $tableName;
1759         }
1760
1761         /**
1762          * @param string|null $namespace Database or schema
1763          * @param string $relation Name of table, view, sequence, etc...
1764          * @param string $format One of (raw, quoted)
1765          * @return string Relation name with quoted and merged $namespace as needed
1766          */
1767         private function prependDatabaseOrSchema( $namespace, $relation, $format ) {
1768                 if ( strlen( $namespace ) ) {
1769                         if ( $format === 'quoted' && !$this->isQuotedIdentifier( $namespace ) ) {
1770                                 $namespace = $this->addIdentifierQuotes( $namespace );
1771                         }
1772                         $relation = $namespace . '.' . $relation;
1773                 }
1774
1775                 return $relation;
1776         }
1777
1778         public function tableNames() {
1779                 $inArray = func_get_args();
1780                 $retVal = [];
1781
1782                 foreach ( $inArray as $name ) {
1783                         $retVal[$name] = $this->tableName( $name );
1784                 }
1785
1786                 return $retVal;
1787         }
1788
1789         public function tableNamesN() {
1790                 $inArray = func_get_args();
1791                 $retVal = [];
1792
1793                 foreach ( $inArray as $name ) {
1794                         $retVal[] = $this->tableName( $name );
1795                 }
1796
1797                 return $retVal;
1798         }
1799
1800         /**
1801          * Get an aliased table name
1802          * e.g. tableName AS newTableName
1803          *
1804          * @param string $name Table name, see tableName()
1805          * @param string|bool $alias Alias (optional)
1806          * @return string SQL name for aliased table. Will not alias a table to its own name
1807          */
1808         protected function tableNameWithAlias( $name, $alias = false ) {
1809                 if ( !$alias || $alias == $name ) {
1810                         return $this->tableName( $name );
1811                 } else {
1812                         return $this->tableName( $name ) . ' ' . $this->addIdentifierQuotes( $alias );
1813                 }
1814         }
1815
1816         /**
1817          * Gets an array of aliased table names
1818          *
1819          * @param array $tables [ [alias] => table ]
1820          * @return string[] See tableNameWithAlias()
1821          */
1822         protected function tableNamesWithAlias( $tables ) {
1823                 $retval = [];
1824                 foreach ( $tables as $alias => $table ) {
1825                         if ( is_numeric( $alias ) ) {
1826                                 $alias = $table;
1827                         }
1828                         $retval[] = $this->tableNameWithAlias( $table, $alias );
1829                 }
1830
1831                 return $retval;
1832         }
1833
1834         /**
1835          * Get an aliased field name
1836          * e.g. fieldName AS newFieldName
1837          *
1838          * @param string $name Field name
1839          * @param string|bool $alias Alias (optional)
1840          * @return string SQL name for aliased field. Will not alias a field to its own name
1841          */
1842         protected function fieldNameWithAlias( $name, $alias = false ) {
1843                 if ( !$alias || (string)$alias === (string)$name ) {
1844                         return $name;
1845                 } else {
1846                         return $name . ' AS ' . $this->addIdentifierQuotes( $alias ); // PostgreSQL needs AS
1847                 }
1848         }
1849
1850         /**
1851          * Gets an array of aliased field names
1852          *
1853          * @param array $fields [ [alias] => field ]
1854          * @return string[] See fieldNameWithAlias()
1855          */
1856         protected function fieldNamesWithAlias( $fields ) {
1857                 $retval = [];
1858                 foreach ( $fields as $alias => $field ) {
1859                         if ( is_numeric( $alias ) ) {
1860                                 $alias = $field;
1861                         }
1862                         $retval[] = $this->fieldNameWithAlias( $field, $alias );
1863                 }
1864
1865                 return $retval;
1866         }
1867
1868         /**
1869          * Get the aliased table name clause for a FROM clause
1870          * which might have a JOIN and/or USE INDEX or IGNORE INDEX clause
1871          *
1872          * @param array $tables ( [alias] => table )
1873          * @param array $use_index Same as for select()
1874          * @param array $ignore_index Same as for select()
1875          * @param array $join_conds Same as for select()
1876          * @return string
1877          */
1878         protected function tableNamesWithIndexClauseOrJOIN(
1879                 $tables, $use_index = [], $ignore_index = [], $join_conds = []
1880         ) {
1881                 $ret = [];
1882                 $retJOIN = [];
1883                 $use_index = (array)$use_index;
1884                 $ignore_index = (array)$ignore_index;
1885                 $join_conds = (array)$join_conds;
1886
1887                 foreach ( $tables as $alias => $table ) {
1888                         if ( !is_string( $alias ) ) {
1889                                 // No alias? Set it equal to the table name
1890                                 $alias = $table;
1891                         }
1892                         // Is there a JOIN clause for this table?
1893                         if ( isset( $join_conds[$alias] ) ) {
1894                                 list( $joinType, $conds ) = $join_conds[$alias];
1895                                 $tableClause = $joinType;
1896                                 $tableClause .= ' ' . $this->tableNameWithAlias( $table, $alias );
1897                                 if ( isset( $use_index[$alias] ) ) { // has USE INDEX?
1898                                         $use = $this->useIndexClause( implode( ',', (array)$use_index[$alias] ) );
1899                                         if ( $use != '' ) {
1900                                                 $tableClause .= ' ' . $use;
1901                                         }
1902                                 }
1903                                 if ( isset( $ignore_index[$alias] ) ) { // has IGNORE INDEX?
1904                                         $ignore = $this->ignoreIndexClause(
1905                                                 implode( ',', (array)$ignore_index[$alias] ) );
1906                                         if ( $ignore != '' ) {
1907                                                 $tableClause .= ' ' . $ignore;
1908                                         }
1909                                 }
1910                                 $on = $this->makeList( (array)$conds, self::LIST_AND );
1911                                 if ( $on != '' ) {
1912                                         $tableClause .= ' ON (' . $on . ')';
1913                                 }
1914
1915                                 $retJOIN[] = $tableClause;
1916                         } elseif ( isset( $use_index[$alias] ) ) {
1917                                 // Is there an INDEX clause for this table?
1918                                 $tableClause = $this->tableNameWithAlias( $table, $alias );
1919                                 $tableClause .= ' ' . $this->useIndexClause(
1920                                                 implode( ',', (array)$use_index[$alias] )
1921                                         );
1922
1923                                 $ret[] = $tableClause;
1924                         } elseif ( isset( $ignore_index[$alias] ) ) {
1925                                 // Is there an INDEX clause for this table?
1926                                 $tableClause = $this->tableNameWithAlias( $table, $alias );
1927                                 $tableClause .= ' ' . $this->ignoreIndexClause(
1928                                                 implode( ',', (array)$ignore_index[$alias] )
1929                                         );
1930
1931                                 $ret[] = $tableClause;
1932                         } else {
1933                                 $tableClause = $this->tableNameWithAlias( $table, $alias );
1934
1935                                 $ret[] = $tableClause;
1936                         }
1937                 }
1938
1939                 // We can't separate explicit JOIN clauses with ',', use ' ' for those
1940                 $implicitJoins = !empty( $ret ) ? implode( ',', $ret ) : "";
1941                 $explicitJoins = !empty( $retJOIN ) ? implode( ' ', $retJOIN ) : "";
1942
1943                 // Compile our final table clause
1944                 return implode( ' ', [ $implicitJoins, $explicitJoins ] );
1945         }
1946
1947         /**
1948          * Get the name of an index in a given table.
1949          *
1950          * @param string $index
1951          * @return string
1952          */
1953         protected function indexName( $index ) {
1954                 return $index;
1955         }
1956
1957         public function addQuotes( $s ) {
1958                 if ( $s instanceof Blob ) {
1959                         $s = $s->fetch();
1960                 }
1961                 if ( $s === null ) {
1962                         return 'NULL';
1963                 } elseif ( is_bool( $s ) ) {
1964                         return (int)$s;
1965                 } else {
1966                         # This will also quote numeric values. This should be harmless,
1967                         # and protects against weird problems that occur when they really
1968                         # _are_ strings such as article titles and string->number->string
1969                         # conversion is not 1:1.
1970                         return "'" . $this->strencode( $s ) . "'";
1971                 }
1972         }
1973
1974         /**
1975          * Quotes an identifier using `backticks` or "double quotes" depending on the database type.
1976          * MySQL uses `backticks` while basically everything else uses double quotes.
1977          * Since MySQL is the odd one out here the double quotes are our generic
1978          * and we implement backticks in DatabaseMysql.
1979          *
1980          * @param string $s
1981          * @return string
1982          */
1983         public function addIdentifierQuotes( $s ) {
1984                 return '"' . str_replace( '"', '""', $s ) . '"';
1985         }
1986
1987         /**
1988          * Returns if the given identifier looks quoted or not according to
1989          * the database convention for quoting identifiers .
1990          *
1991          * @note Do not use this to determine if untrusted input is safe.
1992          *   A malicious user can trick this function.
1993          * @param string $name
1994          * @return bool
1995          */
1996         public function isQuotedIdentifier( $name ) {
1997                 return $name[0] == '"' && substr( $name, -1, 1 ) == '"';
1998         }
1999
2000         /**
2001          * @param string $s
2002          * @return string
2003          */
2004         protected function escapeLikeInternal( $s ) {
2005                 return addcslashes( $s, '\%_' );
2006         }
2007
2008         public function buildLike() {
2009                 $params = func_get_args();
2010
2011                 if ( count( $params ) > 0 && is_array( $params[0] ) ) {
2012                         $params = $params[0];
2013                 }
2014
2015                 $s = '';
2016
2017                 foreach ( $params as $value ) {
2018                         if ( $value instanceof LikeMatch ) {
2019                                 $s .= $value->toString();
2020                         } else {
2021                                 $s .= $this->escapeLikeInternal( $value );
2022                         }
2023                 }
2024
2025                 return " LIKE {$this->addQuotes( $s )} ";
2026         }
2027
2028         public function anyChar() {
2029                 return new LikeMatch( '_' );
2030         }
2031
2032         public function anyString() {
2033                 return new LikeMatch( '%' );
2034         }
2035
2036         public function nextSequenceValue( $seqName ) {
2037                 return null;
2038         }
2039
2040         /**
2041          * USE INDEX clause. Unlikely to be useful for anything but MySQL. This
2042          * is only needed because a) MySQL must be as efficient as possible due to
2043          * its use on Wikipedia, and b) MySQL 4.0 is kind of dumb sometimes about
2044          * which index to pick. Anyway, other databases might have different
2045          * indexes on a given table. So don't bother overriding this unless you're
2046          * MySQL.
2047          * @param string $index
2048          * @return string
2049          */
2050         public function useIndexClause( $index ) {
2051                 return '';
2052         }
2053
2054         /**
2055          * IGNORE INDEX clause. Unlikely to be useful for anything but MySQL. This
2056          * is only needed because a) MySQL must be as efficient as possible due to
2057          * its use on Wikipedia, and b) MySQL 4.0 is kind of dumb sometimes about
2058          * which index to pick. Anyway, other databases might have different
2059          * indexes on a given table. So don't bother overriding this unless you're
2060          * MySQL.
2061          * @param string $index
2062          * @return string
2063          */
2064         public function ignoreIndexClause( $index ) {
2065                 return '';
2066         }
2067
2068         public function replace( $table, $uniqueIndexes, $rows, $fname = __METHOD__ ) {
2069                 $quotedTable = $this->tableName( $table );
2070
2071                 if ( count( $rows ) == 0 ) {
2072                         return;
2073                 }
2074
2075                 # Single row case
2076                 if ( !is_array( reset( $rows ) ) ) {
2077                         $rows = [ $rows ];
2078                 }
2079
2080                 // @FXIME: this is not atomic, but a trx would break affectedRows()
2081                 foreach ( $rows as $row ) {
2082                         # Delete rows which collide
2083                         if ( $uniqueIndexes ) {
2084                                 $sql = "DELETE FROM $quotedTable WHERE ";
2085                                 $first = true;
2086                                 foreach ( $uniqueIndexes as $index ) {
2087                                         if ( $first ) {
2088                                                 $first = false;
2089                                                 $sql .= '( ';
2090                                         } else {
2091                                                 $sql .= ' ) OR ( ';
2092                                         }
2093                                         if ( is_array( $index ) ) {
2094                                                 $first2 = true;
2095                                                 foreach ( $index as $col ) {
2096                                                         if ( $first2 ) {
2097                                                                 $first2 = false;
2098                                                         } else {
2099                                                                 $sql .= ' AND ';
2100                                                         }
2101                                                         $sql .= $col . '=' . $this->addQuotes( $row[$col] );
2102                                                 }
2103                                         } else {
2104                                                 $sql .= $index . '=' . $this->addQuotes( $row[$index] );
2105                                         }
2106                                 }
2107                                 $sql .= ' )';
2108                                 $this->query( $sql, $fname );
2109                         }
2110
2111                         # Now insert the row
2112                         $this->insert( $table, $row, $fname );
2113                 }
2114         }
2115
2116         /**
2117          * REPLACE query wrapper for MySQL and SQLite, which have a native REPLACE
2118          * statement.
2119          *
2120          * @param string $table Table name
2121          * @param array|string $rows Row(s) to insert
2122          * @param string $fname Caller function name
2123          *
2124          * @return ResultWrapper
2125          */
2126         protected function nativeReplace( $table, $rows, $fname ) {
2127                 $table = $this->tableName( $table );
2128
2129                 # Single row case
2130                 if ( !is_array( reset( $rows ) ) ) {
2131                         $rows = [ $rows ];
2132                 }
2133
2134                 $sql = "REPLACE INTO $table (" . implode( ',', array_keys( $rows[0] ) ) . ') VALUES ';
2135                 $first = true;
2136
2137                 foreach ( $rows as $row ) {
2138                         if ( $first ) {
2139                                 $first = false;
2140                         } else {
2141                                 $sql .= ',';
2142                         }
2143
2144                         $sql .= '(' . $this->makeList( $row ) . ')';
2145                 }
2146
2147                 return $this->query( $sql, $fname );
2148         }
2149
2150         public function upsert( $table, array $rows, array $uniqueIndexes, array $set,
2151                 $fname = __METHOD__
2152         ) {
2153                 if ( !count( $rows ) ) {
2154                         return true; // nothing to do
2155                 }
2156
2157                 if ( !is_array( reset( $rows ) ) ) {
2158                         $rows = [ $rows ];
2159                 }
2160
2161                 if ( count( $uniqueIndexes ) ) {
2162                         $clauses = []; // list WHERE clauses that each identify a single row
2163                         foreach ( $rows as $row ) {
2164                                 foreach ( $uniqueIndexes as $index ) {
2165                                         $index = is_array( $index ) ? $index : [ $index ]; // columns
2166                                         $rowKey = []; // unique key to this row
2167                                         foreach ( $index as $column ) {
2168                                                 $rowKey[$column] = $row[$column];
2169                                         }
2170                                         $clauses[] = $this->makeList( $rowKey, self::LIST_AND );
2171                                 }
2172                         }
2173                         $where = [ $this->makeList( $clauses, self::LIST_OR ) ];
2174                 } else {
2175                         $where = false;
2176                 }
2177
2178                 $useTrx = !$this->mTrxLevel;
2179                 if ( $useTrx ) {
2180                         $this->begin( $fname, self::TRANSACTION_INTERNAL );
2181                 }
2182                 try {
2183                         # Update any existing conflicting row(s)
2184                         if ( $where !== false ) {
2185                                 $ok = $this->update( $table, $set, $where, $fname );
2186                         } else {
2187                                 $ok = true;
2188                         }
2189                         # Now insert any non-conflicting row(s)
2190                         $ok = $this->insert( $table, $rows, $fname, [ 'IGNORE' ] ) && $ok;
2191                 } catch ( Exception $e ) {
2192                         if ( $useTrx ) {
2193                                 $this->rollback( $fname, self::FLUSHING_INTERNAL );
2194                         }
2195                         throw $e;
2196                 }
2197                 if ( $useTrx ) {
2198                         $this->commit( $fname, self::FLUSHING_INTERNAL );
2199                 }
2200
2201                 return $ok;
2202         }
2203
2204         public function deleteJoin( $delTable, $joinTable, $delVar, $joinVar, $conds,
2205                 $fname = __METHOD__
2206         ) {
2207                 if ( !$conds ) {
2208                         throw new DBUnexpectedError( $this, __METHOD__ . ' called with empty $conds' );
2209                 }
2210
2211                 $delTable = $this->tableName( $delTable );
2212                 $joinTable = $this->tableName( $joinTable );
2213                 $sql = "DELETE FROM $delTable WHERE $delVar IN (SELECT $joinVar FROM $joinTable ";
2214                 if ( $conds != '*' ) {
2215                         $sql .= 'WHERE ' . $this->makeList( $conds, self::LIST_AND );
2216                 }
2217                 $sql .= ')';
2218
2219                 $this->query( $sql, $fname );
2220         }
2221
2222         public function textFieldSize( $table, $field ) {
2223                 $table = $this->tableName( $table );
2224                 $sql = "SHOW COLUMNS FROM $table LIKE \"$field\";";
2225                 $res = $this->query( $sql, __METHOD__ );
2226                 $row = $this->fetchObject( $res );
2227
2228                 $m = [];
2229
2230                 if ( preg_match( '/\((.*)\)/', $row->Type, $m ) ) {
2231                         $size = $m[1];
2232                 } else {
2233                         $size = -1;
2234                 }
2235
2236                 return $size;
2237         }
2238
2239         public function delete( $table, $conds, $fname = __METHOD__ ) {
2240                 if ( !$conds ) {
2241                         throw new DBUnexpectedError( $this, __METHOD__ . ' called with no conditions' );
2242                 }
2243
2244                 $table = $this->tableName( $table );
2245                 $sql = "DELETE FROM $table";
2246
2247                 if ( $conds != '*' ) {
2248                         if ( is_array( $conds ) ) {
2249                                 $conds = $this->makeList( $conds, self::LIST_AND );
2250                         }
2251                         $sql .= ' WHERE ' . $conds;
2252                 }
2253
2254                 return $this->query( $sql, $fname );
2255         }
2256
2257         public function insertSelect(
2258                 $destTable, $srcTable, $varMap, $conds,
2259                 $fname = __METHOD__, $insertOptions = [], $selectOptions = []
2260         ) {
2261                 if ( $this->cliMode ) {
2262                         // For massive migrations with downtime, we don't want to select everything
2263                         // into memory and OOM, so do all this native on the server side if possible.
2264                         return $this->nativeInsertSelect(
2265                                 $destTable,
2266                                 $srcTable,
2267                                 $varMap,
2268                                 $conds,
2269                                 $fname,
2270                                 $insertOptions,
2271                                 $selectOptions
2272                         );
2273                 }
2274
2275                 // For web requests, do a locking SELECT and then INSERT. This puts the SELECT burden
2276                 // on only the master (without needing row-based-replication). It also makes it easy to
2277                 // know how big the INSERT is going to be.
2278                 $fields = [];
2279                 foreach ( $varMap as $dstColumn => $sourceColumnOrSql ) {
2280                         $fields[] = $this->fieldNameWithAlias( $sourceColumnOrSql, $dstColumn );
2281                 }
2282                 $selectOptions[] = 'FOR UPDATE';
2283                 $res = $this->select( $srcTable, implode( ',', $fields ), $conds, $fname, $selectOptions );
2284                 if ( !$res ) {
2285                         return false;
2286                 }
2287
2288                 $rows = [];
2289                 foreach ( $res as $row ) {
2290                         $rows[] = (array)$row;
2291                 }
2292
2293                 return $this->insert( $destTable, $rows, $fname, $insertOptions );
2294         }
2295
2296         protected function nativeInsertSelect( $destTable, $srcTable, $varMap, $conds,
2297                 $fname = __METHOD__,
2298                 $insertOptions = [], $selectOptions = []
2299         ) {
2300                 $destTable = $this->tableName( $destTable );
2301
2302                 if ( !is_array( $insertOptions ) ) {
2303                         $insertOptions = [ $insertOptions ];
2304                 }
2305
2306                 $insertOptions = $this->makeInsertOptions( $insertOptions );
2307
2308                 if ( !is_array( $selectOptions ) ) {
2309                         $selectOptions = [ $selectOptions ];
2310                 }
2311
2312                 list( $startOpts, $useIndex, $tailOpts, $ignoreIndex ) = $this->makeSelectOptions(
2313                         $selectOptions );
2314
2315                 if ( is_array( $srcTable ) ) {
2316                         $srcTable = implode( ',', array_map( [ $this, 'tableName' ], $srcTable ) );
2317                 } else {
2318                         $srcTable = $this->tableName( $srcTable );
2319                 }
2320
2321                 $sql = "INSERT $insertOptions" .
2322                         " INTO $destTable (" . implode( ',', array_keys( $varMap ) ) . ')' .
2323                         " SELECT $startOpts " . implode( ',', $varMap ) .
2324                         " FROM $srcTable $useIndex $ignoreIndex ";
2325
2326                 if ( $conds != '*' ) {
2327                         if ( is_array( $conds ) ) {
2328                                 $conds = $this->makeList( $conds, self::LIST_AND );
2329                         }
2330                         $sql .= " WHERE $conds";
2331                 }
2332
2333                 $sql .= " $tailOpts";
2334
2335                 return $this->query( $sql, $fname );
2336         }
2337
2338         /**
2339          * Construct a LIMIT query with optional offset. This is used for query
2340          * pages. The SQL should be adjusted so that only the first $limit rows
2341          * are returned. If $offset is provided as well, then the first $offset
2342          * rows should be discarded, and the next $limit rows should be returned.
2343          * If the result of the query is not ordered, then the rows to be returned
2344          * are theoretically arbitrary.
2345          *
2346          * $sql is expected to be a SELECT, if that makes a difference.
2347          *
2348          * The version provided by default works in MySQL and SQLite. It will very
2349          * likely need to be overridden for most other DBMSes.
2350          *
2351          * @param string $sql SQL query we will append the limit too
2352          * @param int $limit The SQL limit
2353          * @param int|bool $offset The SQL offset (default false)
2354          * @throws DBUnexpectedError
2355          * @return string
2356          */
2357         public function limitResult( $sql, $limit, $offset = false ) {
2358                 if ( !is_numeric( $limit ) ) {
2359                         throw new DBUnexpectedError( $this,
2360                                 "Invalid non-numeric limit passed to limitResult()\n" );
2361                 }
2362
2363                 return "$sql LIMIT "
2364                 . ( ( is_numeric( $offset ) && $offset != 0 ) ? "{$offset}," : "" )
2365                 . "{$limit} ";
2366         }
2367
2368         public function unionSupportsOrderAndLimit() {
2369                 return true; // True for almost every DB supported
2370         }
2371
2372         public function unionQueries( $sqls, $all ) {
2373                 $glue = $all ? ') UNION ALL (' : ') UNION (';
2374
2375                 return '(' . implode( $glue, $sqls ) . ')';
2376         }
2377
2378         public function conditional( $cond, $trueVal, $falseVal ) {
2379                 if ( is_array( $cond ) ) {
2380                         $cond = $this->makeList( $cond, self::LIST_AND );
2381                 }
2382
2383                 return " (CASE WHEN $cond THEN $trueVal ELSE $falseVal END) ";
2384         }
2385
2386         public function strreplace( $orig, $old, $new ) {
2387                 return "REPLACE({$orig}, {$old}, {$new})";
2388         }
2389
2390         public function getServerUptime() {
2391                 return 0;
2392         }
2393
2394         public function wasDeadlock() {
2395                 return false;
2396         }
2397
2398         public function wasLockTimeout() {
2399                 return false;
2400         }
2401
2402         public function wasErrorReissuable() {
2403                 return false;
2404         }
2405
2406         public function wasReadOnlyError() {
2407                 return false;
2408         }
2409
2410         /**
2411          * Do not use this method outside of Database/DBError classes
2412          *
2413          * @param integer|string $errno
2414          * @return bool Whether the given query error was a connection drop
2415          */
2416         public function wasConnectionError( $errno ) {
2417                 return false;
2418         }
2419
2420         public function deadlockLoop() {
2421                 $args = func_get_args();
2422                 $function = array_shift( $args );
2423                 $tries = self::DEADLOCK_TRIES;
2424
2425                 $this->begin( __METHOD__ );
2426
2427                 $retVal = null;
2428                 /** @var Exception $e */
2429                 $e = null;
2430                 do {
2431                         try {
2432                                 $retVal = call_user_func_array( $function, $args );
2433                                 break;
2434                         } catch ( DBQueryError $e ) {
2435                                 if ( $this->wasDeadlock() ) {
2436                                         // Retry after a randomized delay
2437                                         usleep( mt_rand( self::DEADLOCK_DELAY_MIN, self::DEADLOCK_DELAY_MAX ) );
2438                                 } else {
2439                                         // Throw the error back up
2440                                         throw $e;
2441                                 }
2442                         }
2443                 } while ( --$tries > 0 );
2444
2445                 if ( $tries <= 0 ) {
2446                         // Too many deadlocks; give up
2447                         $this->rollback( __METHOD__ );
2448                         throw $e;
2449                 } else {
2450                         $this->commit( __METHOD__ );
2451
2452                         return $retVal;
2453                 }
2454         }
2455
2456         public function masterPosWait( DBMasterPos $pos, $timeout ) {
2457                 # Real waits are implemented in the subclass.
2458                 return 0;
2459         }
2460
2461         public function getReplicaPos() {
2462                 # Stub
2463                 return false;
2464         }
2465
2466         public function getMasterPos() {
2467                 # Stub
2468                 return false;
2469         }
2470
2471         public function serverIsReadOnly() {
2472                 return false;
2473         }
2474
2475         final public function onTransactionResolution( callable $callback, $fname = __METHOD__ ) {
2476                 if ( !$this->mTrxLevel ) {
2477                         throw new DBUnexpectedError( $this, "No transaction is active." );
2478                 }
2479                 $this->mTrxEndCallbacks[] = [ $callback, $fname ];
2480         }
2481
2482         final public function onTransactionIdle( callable $callback, $fname = __METHOD__ ) {
2483                 $this->mTrxIdleCallbacks[] = [ $callback, $fname ];
2484                 if ( !$this->mTrxLevel ) {
2485                         $this->runOnTransactionIdleCallbacks( self::TRIGGER_IDLE );
2486                 }
2487         }
2488
2489         final public function onTransactionPreCommitOrIdle( callable $callback, $fname = __METHOD__ ) {
2490                 if ( $this->mTrxLevel ) {
2491                         $this->mTrxPreCommitCallbacks[] = [ $callback, $fname ];
2492                 } else {
2493                         // If no transaction is active, then make one for this callback
2494                         $this->startAtomic( __METHOD__ );
2495                         try {
2496                                 call_user_func( $callback );
2497                                 $this->endAtomic( __METHOD__ );
2498                         } catch ( Exception $e ) {
2499                                 $this->rollback( __METHOD__, self::FLUSHING_INTERNAL );
2500                                 throw $e;
2501                         }
2502                 }
2503         }
2504
2505         final public function setTransactionListener( $name, callable $callback = null ) {
2506                 if ( $callback ) {
2507                         $this->mTrxRecurringCallbacks[$name] = $callback;
2508                 } else {
2509                         unset( $this->mTrxRecurringCallbacks[$name] );
2510                 }
2511         }
2512
2513         /**
2514          * Whether to disable running of post-COMMIT/ROLLBACK callbacks
2515          *
2516          * This method should not be used outside of Database/LoadBalancer
2517          *
2518          * @param bool $suppress
2519          * @since 1.28
2520          */
2521         final public function setTrxEndCallbackSuppression( $suppress ) {
2522                 $this->mTrxEndCallbacksSuppressed = $suppress;
2523         }
2524
2525         /**
2526          * Actually run and consume any "on transaction idle/resolution" callbacks.
2527          *
2528          * This method should not be used outside of Database/LoadBalancer
2529          *
2530          * @param integer $trigger IDatabase::TRIGGER_* constant
2531          * @since 1.20
2532          * @throws Exception
2533          */
2534         public function runOnTransactionIdleCallbacks( $trigger ) {
2535                 if ( $this->mTrxEndCallbacksSuppressed ) {
2536                         return;
2537                 }
2538
2539                 $autoTrx = $this->getFlag( self::DBO_TRX ); // automatic begin() enabled?
2540                 /** @var Exception $e */
2541                 $e = null; // first exception
2542                 do { // callbacks may add callbacks :)
2543                         $callbacks = array_merge(
2544                                 $this->mTrxIdleCallbacks,
2545                                 $this->mTrxEndCallbacks // include "transaction resolution" callbacks
2546                         );
2547                         $this->mTrxIdleCallbacks = []; // consumed (and recursion guard)
2548                         $this->mTrxEndCallbacks = []; // consumed (recursion guard)
2549                         foreach ( $callbacks as $callback ) {
2550                                 try {
2551                                         list( $phpCallback ) = $callback;
2552                                         $this->clearFlag( self::DBO_TRX ); // make each query its own transaction
2553                                         call_user_func_array( $phpCallback, [ $trigger ] );
2554                                         if ( $autoTrx ) {
2555                                                 $this->setFlag( self::DBO_TRX ); // restore automatic begin()
2556                                         } else {
2557                                                 $this->clearFlag( self::DBO_TRX ); // restore auto-commit
2558                                         }
2559                                 } catch ( Exception $ex ) {
2560                                         call_user_func( $this->errorLogger, $ex );
2561                                         $e = $e ?: $ex;
2562                                         // Some callbacks may use startAtomic/endAtomic, so make sure
2563                                         // their transactions are ended so other callbacks don't fail
2564                                         if ( $this->trxLevel() ) {
2565                                                 $this->rollback( __METHOD__, self::FLUSHING_INTERNAL );
2566                                         }
2567                                 }
2568                         }
2569                 } while ( count( $this->mTrxIdleCallbacks ) );
2570
2571                 if ( $e instanceof Exception ) {
2572                         throw $e; // re-throw any first exception
2573                 }
2574         }
2575
2576         /**
2577          * Actually run and consume any "on transaction pre-commit" callbacks.
2578          *
2579          * This method should not be used outside of Database/LoadBalancer
2580          *
2581          * @since 1.22
2582          * @throws Exception
2583          */
2584         public function runOnTransactionPreCommitCallbacks() {
2585                 $e = null; // first exception
2586                 do { // callbacks may add callbacks :)
2587                         $callbacks = $this->mTrxPreCommitCallbacks;
2588                         $this->mTrxPreCommitCallbacks = []; // consumed (and recursion guard)
2589                         foreach ( $callbacks as $callback ) {
2590                                 try {
2591                                         list( $phpCallback ) = $callback;
2592                                         call_user_func( $phpCallback );
2593                                 } catch ( Exception $ex ) {
2594                                         call_user_func( $this->errorLogger, $ex );
2595                                         $e = $e ?: $ex;
2596                                 }
2597                         }
2598                 } while ( count( $this->mTrxPreCommitCallbacks ) );
2599
2600                 if ( $e instanceof Exception ) {
2601                         throw $e; // re-throw any first exception
2602                 }
2603         }
2604
2605         /**
2606          * Actually run any "transaction listener" callbacks.
2607          *
2608          * This method should not be used outside of Database/LoadBalancer
2609          *
2610          * @param integer $trigger IDatabase::TRIGGER_* constant
2611          * @throws Exception
2612          * @since 1.20
2613          */
2614         public function runTransactionListenerCallbacks( $trigger ) {
2615                 if ( $this->mTrxEndCallbacksSuppressed ) {
2616                         return;
2617                 }
2618
2619                 /** @var Exception $e */
2620                 $e = null; // first exception
2621
2622                 foreach ( $this->mTrxRecurringCallbacks as $phpCallback ) {
2623                         try {
2624                                 $phpCallback( $trigger, $this );
2625                         } catch ( Exception $ex ) {
2626                                 call_user_func( $this->errorLogger, $ex );
2627                                 $e = $e ?: $ex;
2628                         }
2629                 }
2630
2631                 if ( $e instanceof Exception ) {
2632                         throw $e; // re-throw any first exception
2633                 }
2634         }
2635
2636         final public function startAtomic( $fname = __METHOD__ ) {
2637                 if ( !$this->mTrxLevel ) {
2638                         $this->begin( $fname, self::TRANSACTION_INTERNAL );
2639                         // If DBO_TRX is set, a series of startAtomic/endAtomic pairs will result
2640                         // in all changes being in one transaction to keep requests transactional.
2641                         if ( !$this->getFlag( self::DBO_TRX ) ) {
2642                                 $this->mTrxAutomaticAtomic = true;
2643                         }
2644                 }
2645
2646                 $this->mTrxAtomicLevels[] = $fname;
2647         }
2648
2649         final public function endAtomic( $fname = __METHOD__ ) {
2650                 if ( !$this->mTrxLevel ) {
2651                         throw new DBUnexpectedError( $this, "No atomic transaction is open (got $fname)." );
2652                 }
2653                 if ( !$this->mTrxAtomicLevels ||
2654                         array_pop( $this->mTrxAtomicLevels ) !== $fname
2655                 ) {
2656                         throw new DBUnexpectedError( $this, "Invalid atomic section ended (got $fname)." );
2657                 }
2658
2659                 if ( !$this->mTrxAtomicLevels && $this->mTrxAutomaticAtomic ) {
2660                         $this->commit( $fname, self::FLUSHING_INTERNAL );
2661                 }
2662         }
2663
2664         final public function doAtomicSection( $fname, callable $callback ) {
2665                 $this->startAtomic( $fname );
2666                 try {
2667                         $res = call_user_func_array( $callback, [ $this, $fname ] );
2668                 } catch ( Exception $e ) {
2669                         $this->rollback( $fname, self::FLUSHING_INTERNAL );
2670                         throw $e;
2671                 }
2672                 $this->endAtomic( $fname );
2673
2674                 return $res;
2675         }
2676
2677         final public function begin( $fname = __METHOD__, $mode = self::TRANSACTION_EXPLICIT ) {
2678                 // Protect against mismatched atomic section, transaction nesting, and snapshot loss
2679                 if ( $this->mTrxLevel ) {
2680                         if ( $this->mTrxAtomicLevels ) {
2681                                 $levels = implode( ', ', $this->mTrxAtomicLevels );
2682                                 $msg = "$fname: Got explicit BEGIN while atomic section(s) $levels are open.";
2683                                 throw new DBUnexpectedError( $this, $msg );
2684                         } elseif ( !$this->mTrxAutomatic ) {
2685                                 $msg = "$fname: Explicit transaction already active (from {$this->mTrxFname}).";
2686                                 throw new DBUnexpectedError( $this, $msg );
2687                         } else {
2688                                 // @TODO: make this an exception at some point
2689                                 $msg = "$fname: Implicit transaction already active (from {$this->mTrxFname}).";
2690                                 $this->queryLogger->error( $msg );
2691                                 return; // join the main transaction set
2692                         }
2693                 } elseif ( $this->getFlag( self::DBO_TRX ) && $mode !== self::TRANSACTION_INTERNAL ) {
2694                         // @TODO: make this an exception at some point
2695                         $msg = "$fname: Implicit transaction expected (DBO_TRX set).";
2696                         $this->queryLogger->error( $msg );
2697                         return; // let any writes be in the main transaction
2698                 }
2699
2700                 // Avoid fatals if close() was called
2701                 $this->assertOpen();
2702
2703                 $this->doBegin( $fname );
2704                 $this->mTrxTimestamp = microtime( true );
2705                 $this->mTrxFname = $fname;
2706                 $this->mTrxDoneWrites = false;
2707                 $this->mTrxAutomaticAtomic = false;
2708                 $this->mTrxAtomicLevels = [];
2709                 $this->mTrxShortId = sprintf( '%06x', mt_rand( 0, 0xffffff ) );
2710                 $this->mTrxWriteDuration = 0.0;
2711                 $this->mTrxWriteQueryCount = 0;
2712                 $this->mTrxWriteAdjDuration = 0.0;
2713                 $this->mTrxWriteAdjQueryCount = 0;
2714                 $this->mTrxWriteCallers = [];
2715                 // First SELECT after BEGIN will establish the snapshot in REPEATABLE-READ.
2716                 // Get an estimate of the replica DB lag before then, treating estimate staleness
2717                 // as lag itself just to be safe
2718                 $status = $this->getApproximateLagStatus();
2719                 $this->mTrxReplicaLag = $status['lag'] + ( microtime( true ) - $status['since'] );
2720                 // T147697: make explicitTrxActive() return true until begin() finishes. This way, no
2721                 // caller will think its OK to muck around with the transaction just because startAtomic()
2722                 // has not yet completed (e.g. setting mTrxAtomicLevels).
2723                 $this->mTrxAutomatic = ( $mode === self::TRANSACTION_INTERNAL );
2724         }
2725
2726         /**
2727          * Issues the BEGIN command to the database server.
2728          *
2729          * @see Database::begin()
2730          * @param string $fname
2731          */
2732         protected function doBegin( $fname ) {
2733                 $this->query( 'BEGIN', $fname );
2734                 $this->mTrxLevel = 1;
2735         }
2736
2737         final public function commit( $fname = __METHOD__, $flush = '' ) {
2738                 if ( $this->mTrxLevel && $this->mTrxAtomicLevels ) {
2739                         // There are still atomic sections open. This cannot be ignored
2740                         $levels = implode( ', ', $this->mTrxAtomicLevels );
2741                         throw new DBUnexpectedError(
2742                                 $this,
2743                                 "$fname: Got COMMIT while atomic sections $levels are still open."
2744                         );
2745                 }
2746
2747                 if ( $flush === self::FLUSHING_INTERNAL || $flush === self::FLUSHING_ALL_PEERS ) {
2748                         if ( !$this->mTrxLevel ) {
2749                                 return; // nothing to do
2750                         } elseif ( !$this->mTrxAutomatic ) {
2751                                 throw new DBUnexpectedError(
2752                                         $this,
2753                                         "$fname: Flushing an explicit transaction, getting out of sync."
2754                                 );
2755                         }
2756                 } else {
2757                         if ( !$this->mTrxLevel ) {
2758                                 $this->queryLogger->error(
2759                                         "$fname: No transaction to commit, something got out of sync." );
2760                                 return; // nothing to do
2761                         } elseif ( $this->mTrxAutomatic ) {
2762                                 // @TODO: make this an exception at some point
2763                                 $msg = "$fname: Explicit commit of implicit transaction.";
2764                                 $this->queryLogger->error( $msg );
2765                                 return; // wait for the main transaction set commit round
2766                         }
2767                 }
2768
2769                 // Avoid fatals if close() was called
2770                 $this->assertOpen();
2771
2772                 $this->runOnTransactionPreCommitCallbacks();
2773                 $writeTime = $this->pendingWriteQueryDuration( self::ESTIMATE_DB_APPLY );
2774                 $this->doCommit( $fname );
2775                 if ( $this->mTrxDoneWrites ) {
2776                         $this->mLastWriteTime = microtime( true );
2777                         $this->trxProfiler->transactionWritingOut(
2778                                 $this->mServer, $this->mDBname, $this->mTrxShortId, $writeTime );
2779                 }
2780
2781                 $this->runOnTransactionIdleCallbacks( self::TRIGGER_COMMIT );
2782                 $this->runTransactionListenerCallbacks( self::TRIGGER_COMMIT );
2783         }
2784
2785         /**
2786          * Issues the COMMIT command to the database server.
2787          *
2788          * @see Database::commit()
2789          * @param string $fname
2790          */
2791         protected function doCommit( $fname ) {
2792                 if ( $this->mTrxLevel ) {
2793                         $this->query( 'COMMIT', $fname );
2794                         $this->mTrxLevel = 0;
2795                 }
2796         }
2797
2798         final public function rollback( $fname = __METHOD__, $flush = '' ) {
2799                 if ( $flush === self::FLUSHING_INTERNAL || $flush === self::FLUSHING_ALL_PEERS ) {
2800                         if ( !$this->mTrxLevel ) {
2801                                 return; // nothing to do
2802                         }
2803                 } else {
2804                         if ( !$this->mTrxLevel ) {
2805                                 $this->queryLogger->error(
2806                                         "$fname: No transaction to rollback, something got out of sync." );
2807                                 return; // nothing to do
2808                         } elseif ( $this->getFlag( self::DBO_TRX ) ) {
2809                                 throw new DBUnexpectedError(
2810                                         $this,
2811                                         "$fname: Expected mass rollback of all peer databases (DBO_TRX set)."
2812                                 );
2813                         }
2814                 }
2815
2816                 // Avoid fatals if close() was called
2817                 $this->assertOpen();
2818
2819                 $this->doRollback( $fname );
2820                 $this->mTrxAtomicLevels = [];
2821                 if ( $this->mTrxDoneWrites ) {
2822                         $this->trxProfiler->transactionWritingOut(
2823                                 $this->mServer, $this->mDBname, $this->mTrxShortId );
2824                 }
2825
2826                 $this->mTrxIdleCallbacks = []; // clear
2827                 $this->mTrxPreCommitCallbacks = []; // clear
2828                 $this->runOnTransactionIdleCallbacks( self::TRIGGER_ROLLBACK );
2829                 $this->runTransactionListenerCallbacks( self::TRIGGER_ROLLBACK );
2830         }
2831
2832         /**
2833          * Issues the ROLLBACK command to the database server.
2834          *
2835          * @see Database::rollback()
2836          * @param string $fname
2837          */
2838         protected function doRollback( $fname ) {
2839                 if ( $this->mTrxLevel ) {
2840                         # Disconnects cause rollback anyway, so ignore those errors
2841                         $ignoreErrors = true;
2842                         $this->query( 'ROLLBACK', $fname, $ignoreErrors );
2843                         $this->mTrxLevel = 0;
2844                 }
2845         }
2846
2847         public function flushSnapshot( $fname = __METHOD__ ) {
2848                 if ( $this->writesOrCallbacksPending() || $this->explicitTrxActive() ) {
2849                         // This only flushes transactions to clear snapshots, not to write data
2850                         $fnames = implode( ', ', $this->pendingWriteAndCallbackCallers() );
2851                         throw new DBUnexpectedError(
2852                                 $this,
2853                                 "$fname: Cannot flush snapshot because writes are pending ($fnames)."
2854                         );
2855                 }
2856
2857                 $this->commit( $fname, self::FLUSHING_INTERNAL );
2858         }
2859
2860         public function explicitTrxActive() {
2861                 return $this->mTrxLevel && ( $this->mTrxAtomicLevels || !$this->mTrxAutomatic );
2862         }
2863
2864         public function duplicateTableStructure(
2865                 $oldName, $newName, $temporary = false, $fname = __METHOD__
2866         ) {
2867                 throw new RuntimeException( __METHOD__ . ' is not implemented in descendant class' );
2868         }
2869
2870         public function listTables( $prefix = null, $fname = __METHOD__ ) {
2871                 throw new RuntimeException( __METHOD__ . ' is not implemented in descendant class' );
2872         }
2873
2874         public function listViews( $prefix = null, $fname = __METHOD__ ) {
2875                 throw new RuntimeException( __METHOD__ . ' is not implemented in descendant class' );
2876         }
2877
2878         public function timestamp( $ts = 0 ) {
2879                 $t = new ConvertibleTimestamp( $ts );
2880                 // Let errors bubble up to avoid putting garbage in the DB
2881                 return $t->getTimestamp( TS_MW );
2882         }
2883
2884         public function timestampOrNull( $ts = null ) {
2885                 if ( is_null( $ts ) ) {
2886                         return null;
2887                 } else {
2888                         return $this->timestamp( $ts );
2889                 }
2890         }
2891
2892         /**
2893          * Take the result from a query, and wrap it in a ResultWrapper if
2894          * necessary. Boolean values are passed through as is, to indicate success
2895          * of write queries or failure.
2896          *
2897          * Once upon a time, Database::query() returned a bare MySQL result
2898          * resource, and it was necessary to call this function to convert it to
2899          * a wrapper. Nowadays, raw database objects are never exposed to external
2900          * callers, so this is unnecessary in external code.
2901          *
2902          * @param bool|ResultWrapper|resource|object $result
2903          * @return bool|ResultWrapper
2904          */
2905         protected function resultObject( $result ) {
2906                 if ( !$result ) {
2907                         return false;
2908                 } elseif ( $result instanceof ResultWrapper ) {
2909                         return $result;
2910                 } elseif ( $result === true ) {
2911                         // Successful write query
2912                         return $result;
2913                 } else {
2914                         return new ResultWrapper( $this, $result );
2915                 }
2916         }
2917
2918         public function ping( &$rtt = null ) {
2919                 // Avoid hitting the server if it was hit recently
2920                 if ( $this->isOpen() && ( microtime( true ) - $this->lastPing ) < self::PING_TTL ) {
2921                         if ( !func_num_args() || $this->mRTTEstimate > 0 ) {
2922                                 $rtt = $this->mRTTEstimate;
2923                                 return true; // don't care about $rtt
2924                         }
2925                 }
2926
2927                 // This will reconnect if possible or return false if not
2928                 $this->clearFlag( self::DBO_TRX, self::REMEMBER_PRIOR );
2929                 $ok = ( $this->query( self::PING_QUERY, __METHOD__, true ) !== false );
2930                 $this->restoreFlags( self::RESTORE_PRIOR );
2931
2932                 if ( $ok ) {
2933                         $rtt = $this->mRTTEstimate;
2934                 }
2935
2936                 return $ok;
2937         }
2938
2939         /**
2940          * @return bool
2941          */
2942         protected function reconnect() {
2943                 $this->closeConnection();
2944                 $this->mOpened = false;
2945                 $this->mConn = false;
2946                 try {
2947                         $this->open( $this->mServer, $this->mUser, $this->mPassword, $this->mDBname );
2948                         $this->lastPing = microtime( true );
2949                         $ok = true;
2950                 } catch ( DBConnectionError $e ) {
2951                         $ok = false;
2952                 }
2953
2954                 return $ok;
2955         }
2956
2957         public function getSessionLagStatus() {
2958                 return $this->getTransactionLagStatus() ?: $this->getApproximateLagStatus();
2959         }
2960
2961         /**
2962          * Get the replica DB lag when the current transaction started
2963          *
2964          * This is useful when transactions might use snapshot isolation
2965          * (e.g. REPEATABLE-READ in innodb), so the "real" lag of that data
2966          * is this lag plus transaction duration. If they don't, it is still
2967          * safe to be pessimistic. This returns null if there is no transaction.
2968          *
2969          * @return array|null ('lag': seconds or false on error, 'since': UNIX timestamp of BEGIN)
2970          * @since 1.27
2971          */
2972         protected function getTransactionLagStatus() {
2973                 return $this->mTrxLevel
2974                         ? [ 'lag' => $this->mTrxReplicaLag, 'since' => $this->trxTimestamp() ]
2975                         : null;
2976         }
2977
2978         /**
2979          * Get a replica DB lag estimate for this server
2980          *
2981          * @return array ('lag': seconds or false on error, 'since': UNIX timestamp of estimate)
2982          * @since 1.27
2983          */
2984         protected function getApproximateLagStatus() {
2985                 return [
2986                         'lag'   => $this->getLBInfo( 'replica' ) ? $this->getLag() : 0,
2987                         'since' => microtime( true )
2988                 ];
2989         }
2990
2991         /**
2992          * Merge the result of getSessionLagStatus() for several DBs
2993          * using the most pessimistic values to estimate the lag of
2994          * any data derived from them in combination
2995          *
2996          * This is information is useful for caching modules
2997          *
2998          * @see WANObjectCache::set()
2999          * @see WANObjectCache::getWithSetCallback()
3000          *
3001          * @param IDatabase $db1
3002          * @param IDatabase ...
3003          * @return array Map of values:
3004          *   - lag: highest lag of any of the DBs or false on error (e.g. replication stopped)
3005          *   - since: oldest UNIX timestamp of any of the DB lag estimates
3006          *   - pending: whether any of the DBs have uncommitted changes
3007          * @since 1.27
3008          */
3009         public static function getCacheSetOptions( IDatabase $db1 ) {
3010                 $res = [ 'lag' => 0, 'since' => INF, 'pending' => false ];
3011                 foreach ( func_get_args() as $db ) {
3012                         /** @var IDatabase $db */
3013                         $status = $db->getSessionLagStatus();
3014                         if ( $status['lag'] === false ) {
3015                                 $res['lag'] = false;
3016                         } elseif ( $res['lag'] !== false ) {
3017                                 $res['lag'] = max( $res['lag'], $status['lag'] );
3018                         }
3019                         $res['since'] = min( $res['since'], $status['since'] );
3020                         $res['pending'] = $res['pending'] ?: $db->writesPending();
3021                 }
3022
3023                 return $res;
3024         }
3025
3026         public function getLag() {
3027                 return 0;
3028         }
3029
3030         public function maxListLen() {
3031                 return 0;
3032         }
3033
3034         public function encodeBlob( $b ) {
3035                 return $b;
3036         }
3037
3038         public function decodeBlob( $b ) {
3039                 if ( $b instanceof Blob ) {
3040                         $b = $b->fetch();
3041                 }
3042                 return $b;
3043         }
3044
3045         public function setSessionOptions( array $options ) {
3046         }
3047
3048         public function sourceFile(
3049                 $filename,
3050                 callable $lineCallback = null,
3051                 callable $resultCallback = null,
3052                 $fname = false,
3053                 callable $inputCallback = null
3054         ) {
3055                 MediaWiki\suppressWarnings();
3056                 $fp = fopen( $filename, 'r' );
3057                 MediaWiki\restoreWarnings();
3058
3059                 if ( false === $fp ) {
3060                         throw new RuntimeException( "Could not open \"{$filename}\".\n" );
3061                 }
3062
3063                 if ( !$fname ) {
3064                         $fname = __METHOD__ . "( $filename )";
3065                 }
3066
3067                 try {
3068                         $error = $this->sourceStream(
3069                                 $fp, $lineCallback, $resultCallback, $fname, $inputCallback );
3070                 } catch ( Exception $e ) {
3071                         fclose( $fp );
3072                         throw $e;
3073                 }
3074
3075                 fclose( $fp );
3076
3077                 return $error;
3078         }
3079
3080         public function setSchemaVars( $vars ) {
3081                 $this->mSchemaVars = $vars;
3082         }
3083
3084         public function sourceStream(
3085                 $fp,
3086                 callable $lineCallback = null,
3087                 callable $resultCallback = null,
3088                 $fname = __METHOD__,
3089                 callable $inputCallback = null
3090         ) {
3091                 $cmd = '';
3092
3093                 while ( !feof( $fp ) ) {
3094                         if ( $lineCallback ) {
3095                                 call_user_func( $lineCallback );
3096                         }
3097
3098                         $line = trim( fgets( $fp ) );
3099
3100                         if ( $line == '' ) {
3101                                 continue;
3102                         }
3103
3104                         if ( '-' == $line[0] && '-' == $line[1] ) {
3105                                 continue;
3106                         }
3107
3108                         if ( $cmd != '' ) {
3109                                 $cmd .= ' ';
3110                         }
3111
3112                         $done = $this->streamStatementEnd( $cmd, $line );
3113
3114                         $cmd .= "$line\n";
3115
3116                         if ( $done || feof( $fp ) ) {
3117                                 $cmd = $this->replaceVars( $cmd );
3118
3119                                 if ( !$inputCallback || call_user_func( $inputCallback, $cmd ) ) {
3120                                         $res = $this->query( $cmd, $fname );
3121
3122                                         if ( $resultCallback ) {
3123                                                 call_user_func( $resultCallback, $res, $this );
3124                                         }
3125
3126                                         if ( false === $res ) {
3127                                                 $err = $this->lastError();
3128
3129                                                 return "Query \"{$cmd}\" failed with error code \"$err\".\n";
3130                                         }
3131                                 }
3132                                 $cmd = '';
3133                         }
3134                 }
3135
3136                 return true;
3137         }
3138
3139         /**
3140          * Called by sourceStream() to check if we've reached a statement end
3141          *
3142          * @param string &$sql SQL assembled so far
3143          * @param string &$newLine New line about to be added to $sql
3144          * @return bool Whether $newLine contains end of the statement
3145          */
3146         public function streamStatementEnd( &$sql, &$newLine ) {
3147                 if ( $this->delimiter ) {
3148                         $prev = $newLine;
3149                         $newLine = preg_replace(
3150                                 '/' . preg_quote( $this->delimiter, '/' ) . '$/', '', $newLine );
3151                         if ( $newLine != $prev ) {
3152                                 return true;
3153                         }
3154                 }
3155
3156                 return false;
3157         }
3158
3159         /**
3160          * Database independent variable replacement. Replaces a set of variables
3161          * in an SQL statement with their contents as given by $this->getSchemaVars().
3162          *
3163          * Supports '{$var}' `{$var}` and / *$var* / (without the spaces) style variables.
3164          *
3165          * - '{$var}' should be used for text and is passed through the database's
3166          *   addQuotes method.
3167          * - `{$var}` should be used for identifiers (e.g. table and database names).
3168          *   It is passed through the database's addIdentifierQuotes method which
3169          *   can be overridden if the database uses something other than backticks.
3170          * - / *_* / or / *$wgDBprefix* / passes the name that follows through the
3171          *   database's tableName method.
3172          * - / *i* / passes the name that follows through the database's indexName method.
3173          * - In all other cases, / *$var* / is left unencoded. Except for table options,
3174          *   its use should be avoided. In 1.24 and older, string encoding was applied.
3175          *
3176          * @param string $ins SQL statement to replace variables in
3177          * @return string The new SQL statement with variables replaced
3178          */
3179         protected function replaceVars( $ins ) {
3180                 $vars = $this->getSchemaVars();
3181                 return preg_replace_callback(
3182                         '!
3183                                 /\* (\$wgDBprefix|[_i]) \*/ (\w*) | # 1-2. tableName, indexName
3184                                 \'\{\$ (\w+) }\'                  | # 3. addQuotes
3185                                 `\{\$ (\w+) }`                    | # 4. addIdentifierQuotes
3186                                 /\*\$ (\w+) \*/                     # 5. leave unencoded
3187                         !x',
3188                         function ( $m ) use ( $vars ) {
3189                                 // Note: Because of <https://bugs.php.net/bug.php?id=51881>,
3190                                 // check for both nonexistent keys *and* the empty string.
3191                                 if ( isset( $m[1] ) && $m[1] !== '' ) {
3192                                         if ( $m[1] === 'i' ) {
3193                                                 return $this->indexName( $m[2] );
3194                                         } else {
3195                                                 return $this->tableName( $m[2] );
3196                                         }
3197                                 } elseif ( isset( $m[3] ) && $m[3] !== '' && array_key_exists( $m[3], $vars ) ) {
3198                                         return $this->addQuotes( $vars[$m[3]] );
3199                                 } elseif ( isset( $m[4] ) && $m[4] !== '' && array_key_exists( $m[4], $vars ) ) {
3200                                         return $this->addIdentifierQuotes( $vars[$m[4]] );
3201                                 } elseif ( isset( $m[5] ) && $m[5] !== '' && array_key_exists( $m[5], $vars ) ) {
3202                                         return $vars[$m[5]];
3203                                 } else {
3204                                         return $m[0];
3205                                 }
3206                         },
3207                         $ins
3208                 );
3209         }
3210
3211         /**
3212          * Get schema variables. If none have been set via setSchemaVars(), then
3213          * use some defaults from the current object.
3214          *
3215          * @return array
3216          */
3217         protected function getSchemaVars() {
3218                 if ( $this->mSchemaVars ) {
3219                         return $this->mSchemaVars;
3220                 } else {
3221                         return $this->getDefaultSchemaVars();
3222                 }
3223         }
3224
3225         /**
3226          * Get schema variables to use if none have been set via setSchemaVars().
3227          *
3228          * Override this in derived classes to provide variables for tables.sql
3229          * and SQL patch files.
3230          *
3231          * @return array
3232          */
3233         protected function getDefaultSchemaVars() {
3234                 return [];
3235         }
3236
3237         public function lockIsFree( $lockName, $method ) {
3238                 return true;
3239         }
3240
3241         public function lock( $lockName, $method, $timeout = 5 ) {
3242                 $this->mNamedLocksHeld[$lockName] = 1;
3243
3244                 return true;
3245         }
3246
3247         public function unlock( $lockName, $method ) {
3248                 unset( $this->mNamedLocksHeld[$lockName] );
3249
3250                 return true;
3251         }
3252
3253         public function getScopedLockAndFlush( $lockKey, $fname, $timeout ) {
3254                 if ( $this->writesOrCallbacksPending() ) {
3255                         // This only flushes transactions to clear snapshots, not to write data
3256                         $fnames = implode( ', ', $this->pendingWriteAndCallbackCallers() );
3257                         throw new DBUnexpectedError(
3258                                 $this,
3259                                 "$fname: Cannot flush pre-lock snapshot because writes are pending ($fnames)."
3260                         );
3261                 }
3262
3263                 if ( !$this->lock( $lockKey, $fname, $timeout ) ) {
3264                         return null;
3265                 }
3266
3267                 $unlocker = new ScopedCallback( function () use ( $lockKey, $fname ) {
3268                         if ( $this->trxLevel() ) {
3269                                 // There is a good chance an exception was thrown, causing any early return
3270                                 // from the caller. Let any error handler get a chance to issue rollback().
3271                                 // If there isn't one, let the error bubble up and trigger server-side rollback.
3272                                 $this->onTransactionResolution(
3273                                         function () use ( $lockKey, $fname ) {
3274                                                 $this->unlock( $lockKey, $fname );
3275                                         },
3276                                         $fname
3277                                 );
3278                         } else {
3279                                 $this->unlock( $lockKey, $fname );
3280                         }
3281                 } );
3282
3283                 $this->commit( $fname, self::FLUSHING_INTERNAL );
3284
3285                 return $unlocker;
3286         }
3287
3288         public function namedLocksEnqueue() {
3289                 return false;
3290         }
3291
3292         /**
3293          * Lock specific tables
3294          *
3295          * @param array $read Array of tables to lock for read access
3296          * @param array $write Array of tables to lock for write access
3297          * @param string $method Name of caller
3298          * @param bool $lowPriority Whether to indicate writes to be LOW PRIORITY
3299          * @return bool
3300          */
3301         public function lockTables( $read, $write, $method, $lowPriority = true ) {
3302                 return true;
3303         }
3304
3305         /**
3306          * Unlock specific tables
3307          *
3308          * @param string $method The caller
3309          * @return bool
3310          */
3311         public function unlockTables( $method ) {
3312                 return true;
3313         }
3314
3315         /**
3316          * Delete a table
3317          * @param string $tableName
3318          * @param string $fName
3319          * @return bool|ResultWrapper
3320          * @since 1.18
3321          */
3322         public function dropTable( $tableName, $fName = __METHOD__ ) {
3323                 if ( !$this->tableExists( $tableName, $fName ) ) {
3324                         return false;
3325                 }
3326                 $sql = "DROP TABLE " . $this->tableName( $tableName ) . " CASCADE";
3327
3328                 return $this->query( $sql, $fName );
3329         }
3330
3331         public function getInfinity() {
3332                 return 'infinity';
3333         }
3334
3335         public function encodeExpiry( $expiry ) {
3336                 return ( $expiry == '' || $expiry == 'infinity' || $expiry == $this->getInfinity() )
3337                         ? $this->getInfinity()
3338                         : $this->timestamp( $expiry );
3339         }
3340
3341         public function decodeExpiry( $expiry, $format = TS_MW ) {
3342                 if ( $expiry == '' || $expiry == 'infinity' || $expiry == $this->getInfinity() ) {
3343                         return 'infinity';
3344                 }
3345
3346                 return ConvertibleTimestamp::convert( $format, $expiry );
3347         }
3348
3349         public function setBigSelects( $value = true ) {
3350                 // no-op
3351         }
3352
3353         public function isReadOnly() {
3354                 return ( $this->getReadOnlyReason() !== false );
3355         }
3356
3357         /**
3358          * @return string|bool Reason this DB is read-only or false if it is not
3359          */
3360         protected function getReadOnlyReason() {
3361                 $reason = $this->getLBInfo( 'readOnlyReason' );
3362
3363                 return is_string( $reason ) ? $reason : false;
3364         }
3365
3366         public function setTableAliases( array $aliases ) {
3367                 $this->tableAliases = $aliases;
3368         }
3369
3370         /**
3371          * @return bool Whether a DB user is required to access the DB
3372          * @since 1.28
3373          */
3374         protected function requiresDatabaseUser() {
3375                 return true;
3376         }
3377
3378         /**
3379          * Get the underlying binding handle, mConn
3380          *
3381          * Makes sure that mConn is set (disconnects and ping() failure can unset it).
3382          * This catches broken callers than catch and ignore disconnection exceptions.
3383          * Unlike checking isOpen(), this is safe to call inside of open().
3384          *
3385          * @return resource|object
3386          * @throws DBUnexpectedError
3387          * @since 1.26
3388          */
3389         protected function getBindingHandle() {
3390                 if ( !$this->mConn ) {
3391                         throw new DBUnexpectedError(
3392                                 $this,
3393                                 'DB connection was already closed or the connection dropped.'
3394                         );
3395                 }
3396
3397                 return $this->mConn;
3398         }
3399
3400         /**
3401          * @since 1.19
3402          * @return string
3403          */
3404         public function __toString() {
3405                 return (string)$this->mConn;
3406         }
3407
3408         /**
3409          * Make sure that copies do not share the same client binding handle
3410          * @throws DBConnectionError
3411          */
3412         public function __clone() {
3413                 $this->connLogger->warning(
3414                         "Cloning " . get_class( $this ) . " is not recomended; forking connection:\n" .
3415                         ( new RuntimeException() )->getTraceAsString()
3416                 );
3417
3418                 if ( $this->isOpen() ) {
3419                         // Open a new connection resource without messing with the old one
3420                         $this->mOpened = false;
3421                         $this->mConn = false;
3422                         $this->mTrxEndCallbacks = []; // don't copy
3423                         $this->handleSessionLoss(); // no trx or locks anymore
3424                         $this->open( $this->mServer, $this->mUser, $this->mPassword, $this->mDBname );
3425                         $this->lastPing = microtime( true );
3426                 }
3427         }
3428
3429         /**
3430          * Called by serialize. Throw an exception when DB connection is serialized.
3431          * This causes problems on some database engines because the connection is
3432          * not restored on unserialize.
3433          */
3434         public function __sleep() {
3435                 throw new RuntimeException( 'Database serialization may cause problems, since ' .
3436                         'the connection is not restored on wakeup.' );
3437         }
3438
3439         /**
3440          * Run a few simple sanity checks and close dangling connections
3441          */
3442         public function __destruct() {
3443                 if ( $this->mTrxLevel && $this->mTrxDoneWrites ) {
3444                         trigger_error( "Uncommitted DB writes (transaction from {$this->mTrxFname})." );
3445                 }
3446
3447                 $danglingWriters = $this->pendingWriteAndCallbackCallers();
3448                 if ( $danglingWriters ) {
3449                         $fnames = implode( ', ', $danglingWriters );
3450                         trigger_error( "DB transaction writes or callbacks still pending ($fnames)." );
3451                 }
3452
3453                 if ( $this->mConn ) {
3454                         // Avoid connection leaks for sanity. Normally, resources close at script completion.
3455                         // The connection might already be closed in zend/hhvm by now, so suppress warnings.
3456                         \MediaWiki\suppressWarnings();
3457                         $this->closeConnection();
3458                         \MediaWiki\restoreWarnings();
3459                         $this->mConn = false;
3460                         $this->mOpened = false;
3461                 }
3462         }
3463 }
3464
3465 class_alias( Database::class, 'DatabaseBase' );