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
  32 /**
  33  * Relational database abstraction object
  34  *
  35  * @ingroup Database
  36  * @since 1.28
  37  */
  38 abstract class Database implements IDatabase, IMaintainableDatabase, LoggerAwareInterface {
  39         /** Number of times to re-try an operation in case of deadlock */
  40         const DEADLOCK_TRIES = 4;
  41         /** Minimum time to wait before retry, in microseconds */
  42         const DEADLOCK_DELAY_MIN = 500000;
  43         /** Maximum time to wait before retry */
  44         const DEADLOCK_DELAY_MAX = 1500000;
  45
  46         /** How long before it is worth doing a dummy query to test the connection */
  47         const PING_TTL = 1.0;
  48         const PING_QUERY = 'SELECT 1 AS ping';
  49
  50         const TINY_WRITE_SEC = .010;
  51         const SLOW_WRITE_SEC = .500;
  52         const SMALL_WRITE_ROWS = 100;
  53
  54         /** @var string SQL query */
  55         protected $mLastQuery = '';
  56         /** @var float|bool UNIX timestamp of last write query */
  57         protected $mLastWriteTime = false;
  58         /** @var string|bool */
  59         protected $mPHPError = false;
  60         /** @var string */
  61         protected $mServer;
  62         /** @var string */
  63         protected $mUser;
  64         /** @var string */
  65         protected $mPassword;
  66         /** @var string */
  67         protected $mDBname;
  68         /** @var array[] $aliases Map of (table => (dbname, schema, prefix) map) */
  69         protected $tableAliases = [];
  70         /** @var bool Whether this PHP instance is for a CLI script */
  71         protected $cliMode;
  72         /** @var string Agent name for query profiling */
  73         protected $agent;
  74
  75         /** @var BagOStuff APC cache */
  76         protected $srvCache;
  77         /** @var LoggerInterface */
  78         protected $connLogger;
  79         /** @var LoggerInterface */
  80         protected $queryLogger;
  81         /** @var callback Error logging callback */
  82         protected $errorLogger;
  83
  84         /** @var resource|null Database connection */
  85         protected $mConn = null;
  86         /** @var bool */
  87         protected $mOpened = false;
  88
  89         /** @var array[] List of (callable, method name) */
  90         protected $mTrxIdleCallbacks = [];
  91         /** @var array[] List of (callable, method name) */
  92         protected $mTrxPreCommitCallbacks = [];
  93         /** @var array[] List of (callable, method name) */
  94         protected $mTrxEndCallbacks = [];
  95         /** @var callable[] Map of (name => callable) */
  96         protected $mTrxRecurringCallbacks = [];
  97         /** @var bool Whether to suppress triggering of transaction end callbacks */
  98         protected $mTrxEndCallbacksSuppressed = false;
  99
 100         /** @var string */
 101         protected $mTablePrefix = '';
 102         /** @var string */
 103         protected $mSchema = '';
 104         /** @var integer */
 105         protected $mFlags;
 106         /** @var array */
 107         protected $mLBInfo = [];
 108         /** @var bool|null */
 109         protected $mDefaultBigSelects = null;
 110         /** @var array|bool */
 111         protected $mSchemaVars = false;
 112         /** @var array */
 113         protected $mSessionVars = [];
 114         /** @var array|null */
 115         protected $preparedArgs;
 116         /** @var string|bool|null Stashed value of html_errors INI setting */
 117         protected $htmlErrors;
 118         /** @var string */
 119         protected $delimiter = ';';
 120         /** @var DatabaseDomain */
 121         protected $currentDomain;
 122
 123         /**
 124          * Either 1 if a transaction is active or 0 otherwise.
 125          * The other Trx fields may not be meaningfull if this is 0.
 126          *
 127          * @var int
 128          */
 129         protected $mTrxLevel = 0;
 130         /**
 131          * Either a short hexidecimal string if a transaction is active or ""
 132          *
 133          * @var string
 134          * @see Database::mTrxLevel
 135          */
 136         protected $mTrxShortId = '';
 137         /**
 138          * The UNIX time that the transaction started. Callers can assume that if
 139          * snapshot isolation is used, then the data is *at least* up to date to that
 140          * point (possibly more up-to-date since the first SELECT defines the snapshot).
 141          *
 142          * @var float|null
 143          * @see Database::mTrxLevel
 144          */
 145         private $mTrxTimestamp = null;
 146         /** @var float Lag estimate at the time of BEGIN */
 147         private $mTrxReplicaLag = null;
 148         /**
 149          * Remembers the function name given for starting the most recent transaction via begin().
 150          * Used to provide additional context for error reporting.
 151          *
 152          * @var string
 153          * @see Database::mTrxLevel
 154          */
 155         private $mTrxFname = null;
 156         /**
 157          * Record if possible write queries were done in the last transaction started
 158          *
 159          * @var bool
 160          * @see Database::mTrxLevel
 161          */
 162         private $mTrxDoneWrites = false;
 163         /**
 164          * Record if the current transaction was started implicitly due to DBO_TRX being set.
 165          *
 166          * @var bool
 167          * @see Database::mTrxLevel
 168          */
 169         private $mTrxAutomatic = false;
 170         /**
 171          * Array of levels of atomicity within transactions
 172          *
 173          * @var array
 174          */
 175         private $mTrxAtomicLevels = [];
 176         /**
 177          * Record if the current transaction was started implicitly by Database::startAtomic
 178          *
 179          * @var bool
 180          */
 181         private $mTrxAutomaticAtomic = false;
 182         /**
 183          * Track the write query callers of the current transaction
 184          *
 185          * @var string[]
 186          */
 187         private $mTrxWriteCallers = [];
 188         /**
 189          * @var float Seconds spent in write queries for the current transaction
 190          */
 191         private $mTrxWriteDuration = 0.0;
 192         /**
 193          * @var integer Number of write queries for the current transaction
 194          */
 195         private $mTrxWriteQueryCount = 0;
 196         /**
 197          * @var float Like mTrxWriteQueryCount but excludes lock-bound, easy to replicate, queries
 198          */
 199         private $mTrxWriteAdjDuration = 0.0;
 200         /**
 201          * @var integer Number of write queries counted in mTrxWriteAdjDuration
 202          */
 203         private $mTrxWriteAdjQueryCount = 0;
 204         /**
 205          * @var float RTT time estimate
 206          */
 207         private $mRTTEstimate = 0.0;
 208
 209         /** @var array Map of (name => 1) for locks obtained via lock() */
 210         private $mNamedLocksHeld = [];
 211         /** @var array Map of (table name => 1) for TEMPORARY tables */
 212         protected $mSessionTempTables = [];
 213
 214         /** @var IDatabase|null Lazy handle to the master DB this server replicates from */
 215         private $lazyMasterHandle;
 216
 217         /** @var float UNIX timestamp */
 218         protected $lastPing = 0.0;
 219
 220         /** @var int[] Prior mFlags values */
 221         private $priorFlags = [];
 222
 223         /** @var object|string Class name or object With profileIn/profileOut methods */
 224         protected $profiler;
 225         /** @var TransactionProfiler */
 226         protected $trxProfiler;
 227
 228         /**
 229          * Constructor and database handle and attempt to connect to the DB server
 230          *
 231          * IDatabase classes should not be constructed directly in external
 232          * code. Database::factory() should be used instead.
 233          *
 234          * @param array $params Parameters passed from Database::factory()
 235          */
 236         function __construct( array $params ) {
 237                 $server = $params['host'];
 238                 $user = $params['user'];
 239                 $password = $params['password'];
 240                 $dbName = $params['dbname'];
 241
 242                 $this->mSchema = $params['schema'];
 243                 $this->mTablePrefix = $params['tablePrefix'];
 244
 245                 $this->cliMode = $params['cliMode'];
 246                 // Agent name is added to SQL queries in a comment, so make sure it can't break out
 247                 $this->agent = str_replace( '/', '-', $params['agent'] );
 248
 249                 $this->mFlags = $params['flags'];
 250                 if ( $this->mFlags & self::DBO_DEFAULT ) {
 251                         if ( $this->cliMode ) {
 252                                 $this->mFlags &= ~self::DBO_TRX;
 253                         } else {
 254                                 $this->mFlags |= self::DBO_TRX;
 255                         }
 256                 }
 257
 258                 $this->mSessionVars = $params['variables'];
 259
 260                 $this->srvCache = isset( $params['srvCache'] )
 261                         ? $params['srvCache']
 262                         : new HashBagOStuff();
 263
 264                 $this->profiler = $params['profiler'];
 265                 $this->trxProfiler = $params['trxProfiler'];
 266                 $this->connLogger = $params['connLogger'];
 267                 $this->queryLogger = $params['queryLogger'];
 268                 $this->errorLogger = $params['errorLogger'];
 269
 270                 // Set initial dummy domain until open() sets the final DB/prefix
 271                 $this->currentDomain = DatabaseDomain::newUnspecified();
 272
 273                 if ( $user ) {
 274                         $this->open( $server, $user, $password, $dbName );
 275                 } elseif ( $this->requiresDatabaseUser() ) {
 276                         throw new InvalidArgumentException( "No database user provided." );
 277                 }
 278
 279                 // Set the domain object after open() sets the relevant fields
 280                 if ( $this->mDBname != '' ) {
 281                         // Domains with server scope but a table prefix are not used by IDatabase classes
 282                         $this->currentDomain = new DatabaseDomain( $this->mDBname, null, $this->mTablePrefix );
 283                 }
 284         }
 285
 286         /**
 287          * Construct a Database subclass instance given a database type and parameters
 288          *
 289          * This also connects to the database immediately upon object construction
 290          *
 291          * @param string $dbType A possible DB type (sqlite, mysql, postgres)
 292          * @param array $p Parameter map with keys:
 293          *   - host : The hostname of the DB server
 294          *   - user : The name of the database user the client operates under
 295          *   - password : The password for the database user
 296          *   - dbname : The name of the database to use where queries do not specify one.
 297          *      The database must exist or an error might be thrown. Setting this to the empty string
 298          *      will avoid any such errors and make the handle have no implicit database scope. This is
 299          *      useful for queries like SHOW STATUS, CREATE DATABASE, or DROP DATABASE. Note that a
 300          *      "database" in Postgres is rougly equivalent to an entire MySQL server. This the domain
 301          *      in which user names and such are defined, e.g. users are database-specific in Postgres.
 302          *   - schema : The database schema to use (if supported). A "schema" in Postgres is roughly
 303          *      equivalent to a "database" in MySQL. Note that MySQL and SQLite do not use schemas.
 304          *   - tablePrefix : Optional table prefix that is implicitly added on to all table names
 305          *      recognized in queries. This can be used in place of schemas for handle site farms.
 306          *   - flags : Optional bitfield of DBO_* constants that define connection, protocol,
 307          *      buffering, and transaction behavior. It is STRONGLY adviced to leave the DBO_DEFAULT
 308          *      flag in place UNLESS this this database simply acts as a key/value store.
 309          *   - driver: Optional name of a specific DB client driver. For MySQL, there is the old
 310          *      'mysql' driver and the newer 'mysqli' driver.
 311          *   - variables: Optional map of session variables to set after connecting. This can be
 312          *      used to adjust lock timeouts or encoding modes and the like.
 313          *   - connLogger: Optional PSR-3 logger interface instance.
 314          *   - queryLogger: Optional PSR-3 logger interface instance.
 315          *   - profiler: Optional class name or object with profileIn()/profileOut() methods.
 316          *      These will be called in query(), using a simplified version of the SQL that also
 317          *      includes the agent as a SQL comment.
 318          *   - trxProfiler: Optional TransactionProfiler instance.
 319          *   - errorLogger: Optional callback that takes an Exception and logs it.
 320          *   - cliMode: Whether to consider the execution context that of a CLI script.
 321          *   - agent: Optional name used to identify the end-user in query profiling/logging.
 322          *   - srvCache: Optional BagOStuff instance to an APC-style cache.
 323          * @return Database|null If the database driver or extension cannot be found
 324          * @throws InvalidArgumentException If the database driver or extension cannot be found
 325          * @since 1.18
 326          */
 327         final public static function factory( $dbType, $p = [] ) {
 328                 static $canonicalDBTypes = [
 329                         'mysql' => [ 'mysqli', 'mysql' ],
 330                         'postgres' => [],
 331                         'sqlite' => [],
 332                         'oracle' => [],
 333                         'mssql' => [],
 334                 ];
 335
 336                 $driver = false;
 337                 $dbType = strtolower( $dbType );
 338                 if ( isset( $canonicalDBTypes[$dbType] ) && $canonicalDBTypes[$dbType] ) {
 339                         $possibleDrivers = $canonicalDBTypes[$dbType];
 340                         if ( !empty( $p['driver'] ) ) {
 341                                 if ( in_array( $p['driver'], $possibleDrivers ) ) {
 342                                         $driver = $p['driver'];
 343                                 } else {
 344                                         throw new InvalidArgumentException( __METHOD__ .
 345                                                 " type '$dbType' does not support driver '{$p['driver']}'" );
 346                                 }
 347                         } else {
 348                                 foreach ( $possibleDrivers as $posDriver ) {
 349                                         if ( extension_loaded( $posDriver ) ) {
 350                                                 $driver = $posDriver;
 351                                                 break;
 352                                         }
 353                                 }
 354                         }
 355                 } else {
 356                         $driver = $dbType;
 357                 }
 358                 if ( $driver === false || $driver === '' ) {
 359                         throw new InvalidArgumentException( __METHOD__ .
 360                                 " no viable database extension found for type '$dbType'" );
 361                 }
 362
 363                 $class = 'Database' . ucfirst( $driver );
 364                 if ( class_exists( $class ) && is_subclass_of( $class, 'IDatabase' ) ) {
 365                         // Resolve some defaults for b/c
 366                         $p['host'] = isset( $p['host'] ) ? $p['host'] : false;
 367                         $p['user'] = isset( $p['user'] ) ? $p['user'] : false;
 368                         $p['password'] = isset( $p['password'] ) ? $p['password'] : false;
 369                         $p['dbname'] = isset( $p['dbname'] ) ? $p['dbname'] : false;
 370                         $p['flags'] = isset( $p['flags'] ) ? $p['flags'] : 0;
 371                         $p['variables'] = isset( $p['variables'] ) ? $p['variables'] : [];
 372                         $p['tablePrefix'] = isset( $p['tablePrefix'] ) ? $p['tablePrefix'] : '';
 373                         $p['schema'] = isset( $p['schema'] ) ? $p['schema'] : '';
 374                         $p['cliMode'] = isset( $p['cliMode'] ) ? $p['cliMode'] : ( PHP_SAPI === 'cli' );
 375                         $p['agent'] = isset( $p['agent'] ) ? $p['agent'] : '';
 376                         if ( !isset( $p['connLogger'] ) ) {
 377                                 $p['connLogger'] = new \Psr\Log\NullLogger();
 378                         }
 379                         if ( !isset( $p['queryLogger'] ) ) {
 380                                 $p['queryLogger'] = new \Psr\Log\NullLogger();
 381                         }
 382                         $p['profiler'] = isset( $p['profiler'] ) ? $p['profiler'] : null;
 383                         if ( !isset( $p['trxProfiler'] ) ) {
 384                                 $p['trxProfiler'] = new TransactionProfiler();
 385                         }
 386                         if ( !isset( $p['errorLogger'] ) ) {
 387                                 $p['errorLogger'] = function ( Exception $e ) {
 388                                         trigger_error( get_class( $e ) . ': ' . $e->getMessage(), E_USER_WARNING );
 389                                 };
 390                         }
 391
 392                         $conn = new $class( $p );
 393                 } else {
 394                         $conn = null;
 395                 }
 396
 397                 return $conn;
 398         }
 399
 400         public function setLogger( LoggerInterface $logger ) {
 401                 $this->queryLogger = $logger;
 402         }
 403
 404         public function getServerInfo() {
 405                 return $this->getServerVersion();
 406         }
 407
 408         public function bufferResults( $buffer = null ) {
 409                 $res = !$this->getFlag( self::DBO_NOBUFFER );
 410                 if ( $buffer !== null ) {
 411                         $buffer
 412                                 ? $this->clearFlag( self::DBO_NOBUFFER )
 413                                 : $this->setFlag( self::DBO_NOBUFFER );
 414                 }
 415
 416                 return $res;
 417         }
 418
 419         /**
 420          * Turns on (false) or off (true) the automatic generation and sending
 421          * of a "we're sorry, but there has been a database error" page on
 422          * database errors. Default is on (false). When turned off, the
 423          * code should use lastErrno() and lastError() to handle the
 424          * situation as appropriate.
 425          *
 426          * Do not use this function outside of the Database classes.
 427          *
 428          * @param null|bool $ignoreErrors
 429          * @return bool The previous value of the flag.
 430          */
 431         protected function ignoreErrors( $ignoreErrors = null ) {
 432                 $res = $this->getFlag( self::DBO_IGNORE );
 433                 if ( $ignoreErrors !== null ) {
 434                         $ignoreErrors
 435                                 ? $this->setFlag( self::DBO_IGNORE )
 436                                 : $this->clearFlag( self::DBO_IGNORE );
 437                 }
 438
 439                 return $res;
 440         }
 441
 442         public function trxLevel() {
 443                 return $this->mTrxLevel;
 444         }
 445
 446         public function trxTimestamp() {
 447                 return $this->mTrxLevel ? $this->mTrxTimestamp : null;
 448         }
 449
 450         public function tablePrefix( $prefix = null ) {
 451                 $old = $this->mTablePrefix;
 452                 if ( $prefix !== null ) {
 453                         $this->mTablePrefix = $prefix;
 454                         $this->currentDomain = ( $this->mDBname != '' )
 455                                 ? new DatabaseDomain( $this->mDBname, null, $this->mTablePrefix )
 456                                 : DatabaseDomain::newUnspecified();
 457                 }
 458
 459                 return $old;
 460         }
 461
 462         public function dbSchema( $schema = null ) {
 463                 $old = $this->mSchema;
 464                 if ( $schema !== null ) {
 465                         $this->mSchema = $schema;
 466                 }
 467
 468                 return $old;
 469         }
 470
 471         public function getLBInfo( $name = null ) {
 472                 if ( is_null( $name ) ) {
 473                         return $this->mLBInfo;
 474                 } else {
 475                         if ( array_key_exists( $name, $this->mLBInfo ) ) {
 476                                 return $this->mLBInfo[$name];
 477                         } else {
 478                                 return null;
 479                         }
 480                 }
 481         }
 482
 483         public function setLBInfo( $name, $value = null ) {
 484                 if ( is_null( $value ) ) {
 485                         $this->mLBInfo = $name;
 486                 } else {
 487                         $this->mLBInfo[$name] = $value;
 488                 }
 489         }
 490
 491         public function setLazyMasterHandle( IDatabase $conn ) {
 492                 $this->lazyMasterHandle = $conn;
 493         }
 494
 495         /**
 496          * @return IDatabase|null
 497          * @see setLazyMasterHandle()
 498          * @since 1.27
 499          */
 500         protected function getLazyMasterHandle() {
 501                 return $this->lazyMasterHandle;
 502         }
 503
 504         public function implicitGroupby() {
 505                 return true;
 506         }
 507
 508         public function implicitOrderby() {
 509                 return true;
 510         }
 511
 512         public function lastQuery() {
 513                 return $this->mLastQuery;
 514         }
 515
 516         public function doneWrites() {
 517                 return (bool)$this->mLastWriteTime;
 518         }
 519
 520         public function lastDoneWrites() {
 521                 return $this->mLastWriteTime ?: false;
 522         }
 523
 524         public function writesPending() {
 525                 return $this->mTrxLevel && $this->mTrxDoneWrites;
 526         }
 527
 528         public function writesOrCallbacksPending() {
 529                 return $this->mTrxLevel && (
 530                         $this->mTrxDoneWrites || $this->mTrxIdleCallbacks || $this->mTrxPreCommitCallbacks
 531                 );
 532         }
 533
 534         public function pendingWriteQueryDuration( $type = self::ESTIMATE_TOTAL ) {
 535                 if ( !$this->mTrxLevel ) {
 536                         return false;
 537                 } elseif ( !$this->mTrxDoneWrites ) {
 538                         return 0.0;
 539                 }
 540
 541                 switch ( $type ) {
 542                         case self::ESTIMATE_DB_APPLY:
 543                                 $this->ping( $rtt );
 544                                 $rttAdjTotal = $this->mTrxWriteAdjQueryCount * $rtt;
 545                                 $applyTime = max( $this->mTrxWriteAdjDuration - $rttAdjTotal, 0 );
 546                                 // For omitted queries, make them count as something at least
 547                                 $omitted = $this->mTrxWriteQueryCount - $this->mTrxWriteAdjQueryCount;
 548                                 $applyTime += self::TINY_WRITE_SEC * $omitted;
 549
 550                                 return $applyTime;
 551                         default: // everything
 552                                 return $this->mTrxWriteDuration;
 553                 }
 554         }
 555
 556         public function pendingWriteCallers() {
 557                 return $this->mTrxLevel ? $this->mTrxWriteCallers : [];
 558         }
 559
 560         protected function pendingWriteAndCallbackCallers() {
 561                 if ( !$this->mTrxLevel ) {
 562                         return [];
 563                 }
 564
 565                 $fnames = $this->mTrxWriteCallers;
 566                 foreach ( [
 567                         $this->mTrxIdleCallbacks,
 568                         $this->mTrxPreCommitCallbacks,
 569                         $this->mTrxEndCallbacks
 570                 ] as $callbacks ) {
 571                         foreach ( $callbacks as $callback ) {
 572                                 $fnames[] = $callback[1];
 573                         }
 574                 }
 575
 576                 return $fnames;
 577         }
 578
 579         public function isOpen() {
 580                 return $this->mOpened;
 581         }
 582
 583         public function setFlag( $flag, $remember = self::REMEMBER_NOTHING ) {
 584                 if ( $remember === self::REMEMBER_PRIOR ) {
 585                         array_push( $this->priorFlags, $this->mFlags );
 586                 }
 587                 $this->mFlags |= $flag;
 588         }
 589
 590         public function clearFlag( $flag, $remember = self::REMEMBER_NOTHING ) {
 591                 if ( $remember === self::REMEMBER_PRIOR ) {
 592                         array_push( $this->priorFlags, $this->mFlags );
 593                 }
 594                 $this->mFlags &= ~$flag;
 595         }
 596
 597         public function restoreFlags( $state = self::RESTORE_PRIOR ) {
 598                 if ( !$this->priorFlags ) {
 599                         return;
 600                 }
 601
 602                 if ( $state === self::RESTORE_INITIAL ) {
 603                         $this->mFlags = reset( $this->priorFlags );
 604                         $this->priorFlags = [];
 605                 } else {
 606                         $this->mFlags = array_pop( $this->priorFlags );
 607                 }
 608         }
 609
 610         public function getFlag( $flag ) {
 611                 return !!( $this->mFlags & $flag );
 612         }
 613
 614         /**
 615          * @param string $name Class field name
 616          * @return mixed
 617          * @deprecated Since 1.28
 618          */
 619         public function getProperty( $name ) {
 620                 return $this->$name;
 621         }
 622
 623         public function getDomainID() {
 624                 return $this->currentDomain->getId();
 625         }
 626
 627         final public function getWikiID() {
 628                 return $this->getDomainID();
 629         }
 630
 631         /**
 632          * Get information about an index into an object
 633          * @param string $table Table name
 634          * @param string $index Index name
 635          * @param string $fname Calling function name
 636          * @return mixed Database-specific index description class or false if the index does not exist
 637          */
 638         abstract function indexInfo( $table, $index, $fname = __METHOD__ );
 639
 640         /**
 641          * Wrapper for addslashes()
 642          *
 643          * @param string $s String to be slashed.
 644          * @return string Slashed string.
 645          */
 646         abstract function strencode( $s );
 647
 648         protected function installErrorHandler() {
 649                 $this->mPHPError = false;
 650                 $this->htmlErrors = ini_set( 'html_errors', '0' );
 651                 set_error_handler( [ $this, 'connectionErrorLogger' ] );
 652         }
 653
 654         /**
 655          * @return bool|string
 656          */
 657         protected function restoreErrorHandler() {
 658                 restore_error_handler();
 659                 if ( $this->htmlErrors !== false ) {
 660                         ini_set( 'html_errors', $this->htmlErrors );
 661                 }
 662
 663                 return $this->getLastPHPError();
 664         }
 665
 666         /**
 667          * @return string|bool Last PHP error for this DB (typically connection errors)
 668          */
 669         protected function getLastPHPError() {
 670                 if ( $this->mPHPError ) {
 671                         $error = preg_replace( '!\[<a.*</a>\]!', '', $this->mPHPError );
 672                         $error = preg_replace( '!^.*?:\s?(.*)$!', '$1', $error );
 673
 674                         return $error;
 675                 }
 676
 677                 return false;
 678         }
 679
 680         /**
 681          * This method should not be used outside of Database classes
 682          *
 683          * @param int $errno
 684          * @param string $errstr
 685          */
 686         public function connectionErrorLogger( $errno, $errstr ) {
 687                 $this->mPHPError = $errstr;
 688         }
 689
 690         /**
 691          * Create a log context to pass to PSR-3 logger functions.
 692          *
 693          * @param array $extras Additional data to add to context
 694          * @return array
 695          */
 696         protected function getLogContext( array $extras = [] ) {
 697                 return array_merge(
 698                         [
 699                                 'db_server' => $this->mServer,
 700                                 'db_name' => $this->mDBname,
 701                                 'db_user' => $this->mUser,
 702                         ],
 703                         $extras
 704                 );
 705         }
 706
 707         public function close() {
 708                 if ( $this->mConn ) {
 709                         if ( $this->trxLevel() ) {
 710                                 $this->commit( __METHOD__, self::FLUSHING_INTERNAL );
 711                         }
 712
 713                         $closed = $this->closeConnection();
 714                         $this->mConn = false;
 715                 } elseif ( $this->mTrxIdleCallbacks || $this->mTrxEndCallbacks ) { // sanity
 716                         throw new RuntimeException( "Transaction callbacks still pending." );
 717                 } else {
 718                         $closed = true;
 719                 }
 720                 $this->mOpened = false;
 721
 722                 return $closed;
 723         }
 724
 725         /**
 726          * Make sure isOpen() returns true as a sanity check
 727          *
 728          * @throws DBUnexpectedError
 729          */
 730         protected function assertOpen() {
 731                 if ( !$this->isOpen() ) {
 732                         throw new DBUnexpectedError( $this, "DB connection was already closed." );
 733                 }
 734         }
 735
 736         /**
 737          * Closes underlying database connection
 738          * @since 1.20
 739          * @return bool Whether connection was closed successfully
 740          */
 741         abstract protected function closeConnection();
 742
 743         public function reportConnectionError( $error = 'Unknown error' ) {
 744                 $myError = $this->lastError();
 745                 if ( $myError ) {
 746                         $error = $myError;
 747                 }
 748
 749                 # New method
 750                 throw new DBConnectionError( $this, $error );
 751         }
 752
 753         /**
 754          * The DBMS-dependent part of query()
 755          *
 756          * @param string $sql SQL query.
 757          * @return ResultWrapper|bool Result object to feed to fetchObject,
 758          *   fetchRow, ...; or false on failure
 759          */
 760         abstract protected function doQuery( $sql );
 761
 762         /**
 763          * Determine whether a query writes to the DB.
 764          * Should return true if unsure.
 765          *
 766          * @param string $sql
 767          * @return bool
 768          */
 769         protected function isWriteQuery( $sql ) {
 770                 return !preg_match(
 771                         '/^(?:SELECT|BEGIN|ROLLBACK|COMMIT|SET|SHOW|EXPLAIN|\(SELECT)\b/i', $sql );
 772         }
 773
 774         /**
 775          * @param $sql
 776          * @return string|null
 777          */
 778         protected function getQueryVerb( $sql ) {
 779                 return preg_match( '/^\s*([a-z]+)/i', $sql, $m ) ? strtoupper( $m[1] ) : null;
 780         }
 781
 782         /**
 783          * Determine whether a SQL statement is sensitive to isolation level.
 784          * A SQL statement is considered transactable if its result could vary
 785          * depending on the transaction isolation level. Operational commands
 786          * such as 'SET' and 'SHOW' are not considered to be transactable.
 787          *
 788          * @param string $sql
 789          * @return bool
 790          */
 791         protected function isTransactableQuery( $sql ) {
 792                 return !in_array(
 793                         $this->getQueryVerb( $sql ),
 794                         [ 'BEGIN', 'COMMIT', 'ROLLBACK', 'SHOW', 'SET', 'CREATE', 'ALTER' ],
 795                         true
 796                 );
 797         }
 798
 799         /**
 800          * @param string $sql A SQL query
 801          * @return bool Whether $sql is SQL for creating/dropping a new TEMPORARY table
 802          */
 803         protected function registerTempTableOperation( $sql ) {
 804                 if ( preg_match(
 805                         '/^CREATE\s+TEMPORARY\s+TABLE\s+(?:IF\s+NOT\s+EXISTS\s+)?[`"\']?(\w+)[`"\']?/i',
 806                         $sql,
 807                         $matches
 808                 ) ) {
 809                         $this->mSessionTempTables[$matches[1]] = 1;
 810
 811                         return true;
 812                 } elseif ( preg_match(
 813                         '/^DROP\s+(?:TEMPORARY\s+)?TABLE\s+(?:IF\s+EXISTS\s+)?[`"\']?(\w+)[`"\']?/i',
 814                         $sql,
 815                         $matches
 816                 ) ) {
 817                         unset( $this->mSessionTempTables[$matches[1]] );
 818
 819                         return true;
 820                 } elseif ( preg_match(
 821                         '/^(?:INSERT\s+(?:\w+\s+)?INTO|UPDATE|DELETE\s+FROM)\s+[`"\']?(\w+)[`"\']?/i',
 822                         $sql,
 823                         $matches
 824                 ) ) {
 825                         return isset( $this->mSessionTempTables[$matches[1]] );
 826                 }
 827
 828                 return false;
 829         }
 830
 831         public function query( $sql, $fname = __METHOD__, $tempIgnore = false ) {
 832                 $priorWritesPending = $this->writesOrCallbacksPending();
 833                 $this->mLastQuery = $sql;
 834
 835                 $isWrite = $this->isWriteQuery( $sql ) && !$this->registerTempTableOperation( $sql );
 836                 if ( $isWrite ) {
 837                         $reason = $this->getReadOnlyReason();
 838                         if ( $reason !== false ) {
 839                                 throw new DBReadOnlyError( $this, "Database is read-only: $reason" );
 840                         }
 841                         # Set a flag indicating that writes have been done
 842                         $this->mLastWriteTime = microtime( true );
 843                 }
 844
 845                 // Add trace comment to the begin of the sql string, right after the operator.
 846                 // Or, for one-word queries (like "BEGIN" or COMMIT") add it to the end (bug 42598)
 847                 $commentedSql = preg_replace( '/\s|$/', " /* $fname {$this->agent} */ ", $sql, 1 );
 848
 849                 # Start implicit transactions that wrap the request if DBO_TRX is enabled
 850                 if ( !$this->mTrxLevel && $this->getFlag( self::DBO_TRX )
 851                         && $this->isTransactableQuery( $sql )
 852                 ) {
 853                         $this->begin( __METHOD__ . " ($fname)", self::TRANSACTION_INTERNAL );
 854                         $this->mTrxAutomatic = true;
 855                 }
 856
 857                 # Keep track of whether the transaction has write queries pending
 858                 if ( $this->mTrxLevel && !$this->mTrxDoneWrites && $isWrite ) {
 859                         $this->mTrxDoneWrites = true;
 860                         $this->trxProfiler->transactionWritingIn(
 861                                 $this->mServer, $this->mDBname, $this->mTrxShortId );
 862                 }
 863
 864                 if ( $this->getFlag( self::DBO_DEBUG ) ) {
 865                         $this->queryLogger->debug( "{$this->mDBname} {$commentedSql}" );
 866                 }
 867
 868                 # Avoid fatals if close() was called
 869                 $this->assertOpen();
 870
 871                 # Send the query to the server
 872                 $ret = $this->doProfiledQuery( $sql, $commentedSql, $isWrite, $fname );
 873
 874                 # Try reconnecting if the connection was lost
 875                 if ( false === $ret && $this->wasErrorReissuable() ) {
 876                         $recoverable = $this->canRecoverFromDisconnect( $sql, $priorWritesPending );
 877                         # Stash the last error values before anything might clear them
 878                         $lastError = $this->lastError();
 879                         $lastErrno = $this->lastErrno();
 880                         # Update state tracking to reflect transaction loss due to disconnection
 881                         $this->handleSessionLoss();
 882                         if ( $this->reconnect() ) {
 883                                 $msg = __METHOD__ . ": lost connection to {$this->getServer()}; reconnected";
 884                                 $this->connLogger->warning( $msg );
 885                                 $this->queryLogger->warning(
 886                                         "$msg:\n" . ( new RuntimeException() )->getTraceAsString() );
 887
 888                                 if ( !$recoverable ) {
 889                                         # Callers may catch the exception and continue to use the DB
 890                                         $this->reportQueryError( $lastError, $lastErrno, $sql, $fname );
 891                                 } else {
 892                                         # Should be safe to silently retry the query
 893                                         $ret = $this->doProfiledQuery( $sql, $commentedSql, $isWrite, $fname );
 894                                 }
 895                         } else {
 896                                 $msg = __METHOD__ . ": lost connection to {$this->getServer()} permanently";
 897                                 $this->connLogger->error( $msg );
 898                         }
 899                 }
 900
 901                 if ( false === $ret ) {
 902                         # Deadlocks cause the entire transaction to abort, not just the statement.
 903                         # https://dev.mysql.com/doc/refman/5.7/en/innodb-error-handling.html
 904                         # https://www.postgresql.org/docs/9.1/static/explicit-locking.html
 905                         if ( $this->wasDeadlock() ) {
 906                                 if ( $this->explicitTrxActive() || $priorWritesPending ) {
 907                                         $tempIgnore = false; // not recoverable
 908                                 }
 909                                 # Update state tracking to reflect transaction loss
 910                                 $this->handleSessionLoss();
 911                         }
 912
 913                         $this->reportQueryError(
 914                                 $this->lastError(), $this->lastErrno(), $sql, $fname, $tempIgnore );
 915                 }
 916
 917                 $res = $this->resultObject( $ret );
 918
 919                 return $res;
 920         }
 921
 922         private function doProfiledQuery( $sql, $commentedSql, $isWrite, $fname ) {
 923                 $isMaster = !is_null( $this->getLBInfo( 'master' ) );
 924                 # generalizeSQL() will probably cut down the query to reasonable
 925                 # logging size most of the time. The substr is really just a sanity check.
 926                 if ( $isMaster ) {
 927                         $queryProf = 'query-m: ' . substr( self::generalizeSQL( $sql ), 0, 255 );
 928                 } else {
 929                         $queryProf = 'query: ' . substr( self::generalizeSQL( $sql ), 0, 255 );
 930                 }
 931
 932                 # Include query transaction state
 933                 $queryProf .= $this->mTrxShortId ? " [TRX#{$this->mTrxShortId}]" : "";
 934
 935                 $startTime = microtime( true );
 936                 if ( $this->profiler ) {
 937                         call_user_func( [ $this->profiler, 'profileIn' ], $queryProf );
 938                 }
 939                 $ret = $this->doQuery( $commentedSql );
 940                 if ( $this->profiler ) {
 941                         call_user_func( [ $this->profiler, 'profileOut' ], $queryProf );
 942                 }
 943                 $queryRuntime = max( microtime( true ) - $startTime, 0.0 );
 944
 945                 unset( $queryProfSection ); // profile out (if set)
 946
 947                 if ( $ret !== false ) {
 948                         $this->lastPing = $startTime;
 949                         if ( $isWrite && $this->mTrxLevel ) {
 950                                 $this->updateTrxWriteQueryTime( $sql, $queryRuntime );
 951                                 $this->mTrxWriteCallers[] = $fname;
 952                         }
 953                 }
 954
 955                 if ( $sql === self::PING_QUERY ) {
 956                         $this->mRTTEstimate = $queryRuntime;
 957                 }
 958
 959                 $this->trxProfiler->recordQueryCompletion(
 960                         $queryProf, $startTime, $isWrite, $this->affectedRows()
 961                 );
 962                 $this->queryLogger->debug( $sql, [
 963                         'method' => $fname,
 964                         'master' => $isMaster,
 965                         'runtime' => $queryRuntime,
 966                 ] );
 967
 968                 return $ret;
 969         }
 970
 971         /**
 972          * Update the estimated run-time of a query, not counting large row lock times
 973          *
 974          * LoadBalancer can be set to rollback transactions that will create huge replication
 975          * lag. It bases this estimate off of pendingWriteQueryDuration(). Certain simple
 976          * queries, like inserting a row can take a long time due to row locking. This method
 977          * uses some simple heuristics to discount those cases.
 978          *
 979          * @param string $sql A SQL write query
 980          * @param float $runtime Total runtime, including RTT
 981          */
 982         private function updateTrxWriteQueryTime( $sql, $runtime ) {
 983                 // Whether this is indicative of replica DB runtime (except for RBR or ws_repl)
 984                 $indicativeOfReplicaRuntime = true;
 985                 if ( $runtime > self::SLOW_WRITE_SEC ) {
 986                         $verb = $this->getQueryVerb( $sql );
 987                         // insert(), upsert(), replace() are fast unless bulky in size or blocked on locks
 988                         if ( $verb === 'INSERT' ) {
 989                                 $indicativeOfReplicaRuntime = $this->affectedRows() > self::SMALL_WRITE_ROWS;
 990                         } elseif ( $verb === 'REPLACE' ) {
 991                                 $indicativeOfReplicaRuntime = $this->affectedRows() > self::SMALL_WRITE_ROWS / 2;
 992                         }
 993                 }
 994
 995                 $this->mTrxWriteDuration += $runtime;
 996                 $this->mTrxWriteQueryCount += 1;
 997                 if ( $indicativeOfReplicaRuntime ) {
 998                         $this->mTrxWriteAdjDuration += $runtime;
 999                         $this->mTrxWriteAdjQueryCount += 1;
1000                 }
1001         }
1002
1003         private function canRecoverFromDisconnect( $sql, $priorWritesPending ) {
1004                 # Transaction dropped; this can mean lost writes, or REPEATABLE-READ snapshots.
1005                 # Dropped connections also mean that named locks are automatically released.
1006                 # Only allow error suppression in autocommit mode or when the lost transaction
1007                 # didn't matter anyway (aside from DBO_TRX snapshot loss).
1008                 if ( $this->mNamedLocksHeld ) {
1009                         return false; // possible critical section violation
1010                 } elseif ( $sql === 'COMMIT' ) {
1011                         return !$priorWritesPending; // nothing written anyway? (T127428)
1012                 } elseif ( $sql === 'ROLLBACK' ) {
1013                         return true; // transaction lost...which is also what was requested :)
1014                 } elseif ( $this->explicitTrxActive() ) {
1015                         return false; // don't drop atomocity
1016                 } elseif ( $priorWritesPending ) {
1017                         return false; // prior writes lost from implicit transaction
1018                 }
1019
1020                 return true;
1021         }
1022
1023         private function handleSessionLoss() {
1024                 $this->mTrxLevel = 0;
1025                 $this->mTrxIdleCallbacks = []; // bug 65263
1026                 $this->mTrxPreCommitCallbacks = []; // bug 65263
1027                 $this->mSessionTempTables = [];
1028                 $this->mNamedLocksHeld = [];
1029                 try {
1030                         // Handle callbacks in mTrxEndCallbacks
1031                         $this->runOnTransactionIdleCallbacks( self::TRIGGER_ROLLBACK );
1032                         $this->runTransactionListenerCallbacks( self::TRIGGER_ROLLBACK );
1033                         return null;
1034                 } catch ( Exception $e ) {
1035                         // Already logged; move on...
1036                         return $e;
1037                 }
1038         }
1039
1040         public function reportQueryError( $error, $errno, $sql, $fname, $tempIgnore = false ) {
1041                 if ( $this->ignoreErrors() || $tempIgnore ) {
1042                         $this->queryLogger->debug( "SQL ERROR (ignored): $error\n" );
1043                 } else {
1044                         $sql1line = mb_substr( str_replace( "\n", "\\n", $sql ), 0, 5 * 1024 );
1045                         $this->queryLogger->error(
1046                                 "{fname}\t{db_server}\t{errno}\t{error}\t{sql1line}",
1047                                 $this->getLogContext( [
1048                                         'method' => __METHOD__,
1049                                         'errno' => $errno,
1050                                         'error' => $error,
1051                                         'sql1line' => $sql1line,
1052                                         'fname' => $fname,
1053                                 ] )
1054                         );
1055                         $this->queryLogger->debug( "SQL ERROR: " . $error . "\n" );
1056                         throw new DBQueryError( $this, $error, $errno, $sql, $fname );
1057                 }
1058         }
1059
1060         public function freeResult( $res ) {
1061         }
1062
1063         public function selectField(
1064                 $table, $var, $cond = '', $fname = __METHOD__, $options = []
1065         ) {
1066                 if ( $var === '*' ) { // sanity
1067                         throw new DBUnexpectedError( $this, "Cannot use a * field: got '$var'" );
1068                 }
1069
1070                 if ( !is_array( $options ) ) {
1071                         $options = [ $options ];
1072                 }
1073
1074                 $options['LIMIT'] = 1;
1075
1076                 $res = $this->select( $table, $var, $cond, $fname, $options );
1077                 if ( $res === false || !$this->numRows( $res ) ) {
1078                         return false;
1079                 }
1080
1081                 $row = $this->fetchRow( $res );
1082
1083                 if ( $row !== false ) {
1084                         return reset( $row );
1085                 } else {
1086                         return false;
1087                 }
1088         }
1089
1090         public function selectFieldValues(
1091                 $table, $var, $cond = '', $fname = __METHOD__, $options = [], $join_conds = []
1092         ) {
1093                 if ( $var === '*' ) { // sanity
1094                         throw new DBUnexpectedError( $this, "Cannot use a * field" );
1095                 } elseif ( !is_string( $var ) ) { // sanity
1096                         throw new DBUnexpectedError( $this, "Cannot use an array of fields" );
1097                 }
1098
1099                 if ( !is_array( $options ) ) {
1100                         $options = [ $options ];
1101                 }
1102
1103                 $res = $this->select( $table, $var, $cond, $fname, $options, $join_conds );
1104                 if ( $res === false ) {
1105                         return false;
1106                 }
1107
1108                 $values = [];
1109                 foreach ( $res as $row ) {
1110                         $values[] = $row->$var;
1111                 }
1112
1113                 return $values;
1114         }
1115
1116         /**
1117          * Returns an optional USE INDEX clause to go after the table, and a
1118          * string to go at the end of the query.
1119          *
1120          * @param array $options Associative array of options to be turned into
1121          *   an SQL query, valid keys are listed in the function.
1122          * @return array
1123          * @see Database::select()
1124          */
1125         protected function makeSelectOptions( $options ) {
1126                 $preLimitTail = $postLimitTail = '';
1127                 $startOpts = '';
1128
1129                 $noKeyOptions = [];
1130
1131                 foreach ( $options as $key => $option ) {
1132                         if ( is_numeric( $key ) ) {
1133                                 $noKeyOptions[$option] = true;
1134                         }
1135                 }
1136
1137                 $preLimitTail .= $this->makeGroupByWithHaving( $options );
1138
1139                 $preLimitTail .= $this->makeOrderBy( $options );
1140
1141                 // if (isset($options['LIMIT'])) {
1142                 //      $tailOpts .= $this->limitResult('', $options['LIMIT'],
1143                 //              isset($options['OFFSET']) ? $options['OFFSET']
1144                 //              : false);
1145                 // }
1146
1147                 if ( isset( $noKeyOptions['FOR UPDATE'] ) ) {
1148                         $postLimitTail .= ' FOR UPDATE';
1149                 }
1150
1151                 if ( isset( $noKeyOptions['LOCK IN SHARE MODE'] ) ) {
1152                         $postLimitTail .= ' LOCK IN SHARE MODE';
1153                 }
1154
1155                 if ( isset( $noKeyOptions['DISTINCT'] ) || isset( $noKeyOptions['DISTINCTROW'] ) ) {
1156                         $startOpts .= 'DISTINCT';
1157                 }
1158
1159                 # Various MySQL extensions
1160                 if ( isset( $noKeyOptions['STRAIGHT_JOIN'] ) ) {
1161                         $startOpts .= ' /*! STRAIGHT_JOIN */';
1162                 }
1163
1164                 if ( isset( $noKeyOptions['HIGH_PRIORITY'] ) ) {
1165                         $startOpts .= ' HIGH_PRIORITY';
1166                 }
1167
1168                 if ( isset( $noKeyOptions['SQL_BIG_RESULT'] ) ) {
1169                         $startOpts .= ' SQL_BIG_RESULT';
1170                 }
1171
1172                 if ( isset( $noKeyOptions['SQL_BUFFER_RESULT'] ) ) {
1173                         $startOpts .= ' SQL_BUFFER_RESULT';
1174                 }
1175
1176                 if ( isset( $noKeyOptions['SQL_SMALL_RESULT'] ) ) {
1177                         $startOpts .= ' SQL_SMALL_RESULT';
1178                 }
1179
1180                 if ( isset( $noKeyOptions['SQL_CALC_FOUND_ROWS'] ) ) {
1181                         $startOpts .= ' SQL_CALC_FOUND_ROWS';
1182                 }
1183
1184                 if ( isset( $noKeyOptions['SQL_CACHE'] ) ) {
1185                         $startOpts .= ' SQL_CACHE';
1186                 }
1187
1188                 if ( isset( $noKeyOptions['SQL_NO_CACHE'] ) ) {
1189                         $startOpts .= ' SQL_NO_CACHE';
1190                 }
1191
1192                 if ( isset( $options['USE INDEX'] ) && is_string( $options['USE INDEX'] ) ) {
1193                         $useIndex = $this->useIndexClause( $options['USE INDEX'] );
1194                 } else {
1195                         $useIndex = '';
1196                 }
1197                 if ( isset( $options['IGNORE INDEX'] ) && is_string( $options['IGNORE INDEX'] ) ) {
1198                         $ignoreIndex = $this->ignoreIndexClause( $options['IGNORE INDEX'] );
1199                 } else {
1200                         $ignoreIndex = '';
1201                 }
1202
1203                 return [ $startOpts, $useIndex, $preLimitTail, $postLimitTail, $ignoreIndex ];
1204         }
1205
1206         /**
1207          * Returns an optional GROUP BY with an optional HAVING
1208          *
1209          * @param array $options Associative array of options
1210          * @return string
1211          * @see Database::select()
1212          * @since 1.21
1213          */
1214         protected function makeGroupByWithHaving( $options ) {
1215                 $sql = '';
1216                 if ( isset( $options['GROUP BY'] ) ) {
1217                         $gb = is_array( $options['GROUP BY'] )
1218                                 ? implode( ',', $options['GROUP BY'] )
1219                                 : $options['GROUP BY'];
1220                         $sql .= ' GROUP BY ' . $gb;
1221                 }
1222                 if ( isset( $options['HAVING'] ) ) {
1223                         $having = is_array( $options['HAVING'] )
1224                                 ? $this->makeList( $options['HAVING'], self::LIST_AND )
1225                                 : $options['HAVING'];
1226                         $sql .= ' HAVING ' . $having;
1227                 }
1228
1229                 return $sql;
1230         }
1231
1232         /**
1233          * Returns an optional ORDER BY
1234          *
1235          * @param array $options Associative array of options
1236          * @return string
1237          * @see Database::select()
1238          * @since 1.21
1239          */
1240         protected function makeOrderBy( $options ) {
1241                 if ( isset( $options['ORDER BY'] ) ) {
1242                         $ob = is_array( $options['ORDER BY'] )
1243                                 ? implode( ',', $options['ORDER BY'] )
1244                                 : $options['ORDER BY'];
1245
1246                         return ' ORDER BY ' . $ob;
1247                 }
1248
1249                 return '';
1250         }
1251
1252         public function select( $table, $vars, $conds = '', $fname = __METHOD__,
1253                 $options = [], $join_conds = [] ) {
1254                 $sql = $this->selectSQLText( $table, $vars, $conds, $fname, $options, $join_conds );
1255
1256                 return $this->query( $sql, $fname );
1257         }
1258
1259         public function selectSQLText( $table, $vars, $conds = '', $fname = __METHOD__,
1260                 $options = [], $join_conds = []
1261         ) {
1262                 if ( is_array( $vars ) ) {
1263                         $vars = implode( ',', $this->fieldNamesWithAlias( $vars ) );
1264                 }
1265
1266                 $options = (array)$options;
1267                 $useIndexes = ( isset( $options['USE INDEX'] ) && is_array( $options['USE INDEX'] ) )
1268                         ? $options['USE INDEX']
1269                         : [];
1270                 $ignoreIndexes = (
1271                         isset( $options['IGNORE INDEX'] ) &&
1272                         is_array( $options['IGNORE INDEX'] )
1273                 )
1274                         ? $options['IGNORE INDEX']
1275                         : [];
1276
1277                 if ( is_array( $table ) ) {
1278                         $from = ' FROM ' .
1279                                 $this->tableNamesWithIndexClauseOrJOIN(
1280                                         $table, $useIndexes, $ignoreIndexes, $join_conds );
1281                 } elseif ( $table != '' ) {
1282                         if ( $table[0] == ' ' ) {
1283                                 $from = ' FROM ' . $table;
1284                         } else {
1285                                 $from = ' FROM ' .
1286                                         $this->tableNamesWithIndexClauseOrJOIN(
1287                                                 [ $table ], $useIndexes, $ignoreIndexes, [] );
1288                         }
1289                 } else {
1290                         $from = '';
1291                 }
1292
1293                 list( $startOpts, $useIndex, $preLimitTail, $postLimitTail, $ignoreIndex ) =
1294                         $this->makeSelectOptions( $options );
1295
1296                 if ( !empty( $conds ) ) {
1297                         if ( is_array( $conds ) ) {
1298                                 $conds = $this->makeList( $conds, self::LIST_AND );
1299                         }
1300                         $sql = "SELECT $startOpts $vars $from $useIndex $ignoreIndex " .
1301                                 "WHERE $conds $preLimitTail";
1302                 } else {
1303                         $sql = "SELECT $startOpts $vars $from $useIndex $ignoreIndex $preLimitTail";
1304                 }
1305
1306                 if ( isset( $options['LIMIT'] ) ) {
1307                         $sql = $this->limitResult( $sql, $options['LIMIT'],
1308                                 isset( $options['OFFSET'] ) ? $options['OFFSET'] : false );
1309                 }
1310                 $sql = "$sql $postLimitTail";
1311
1312                 if ( isset( $options['EXPLAIN'] ) ) {
1313                         $sql = 'EXPLAIN ' . $sql;
1314                 }
1315
1316                 return $sql;
1317         }
1318
1319         public function selectRow( $table, $vars, $conds, $fname = __METHOD__,
1320                 $options = [], $join_conds = []
1321         ) {
1322                 $options = (array)$options;
1323                 $options['LIMIT'] = 1;
1324                 $res = $this->select( $table, $vars, $conds, $fname, $options, $join_conds );
1325
1326                 if ( $res === false ) {
1327                         return false;
1328                 }
1329
1330                 if ( !$this->numRows( $res ) ) {
1331                         return false;
1332                 }
1333
1334                 $obj = $this->fetchObject( $res );
1335
1336                 return $obj;
1337         }
1338
1339         public function estimateRowCount(
1340                 $table, $vars = '*', $conds = '', $fname = __METHOD__, $options = []
1341         ) {
1342                 $rows = 0;
1343                 $res = $this->select( $table, [ 'rowcount' => 'COUNT(*)' ], $conds, $fname, $options );
1344
1345                 if ( $res ) {
1346                         $row = $this->fetchRow( $res );
1347                         $rows = ( isset( $row['rowcount'] ) ) ? (int)$row['rowcount'] : 0;
1348                 }
1349
1350                 return $rows;
1351         }
1352
1353         public function selectRowCount(
1354                 $tables, $vars = '*', $conds = '', $fname = __METHOD__, $options = [], $join_conds = []
1355         ) {
1356                 $rows = 0;
1357                 $sql = $this->selectSQLText( $tables, '1', $conds, $fname, $options, $join_conds );
1358                 $res = $this->query( "SELECT COUNT(*) AS rowcount FROM ($sql) tmp_count", $fname );
1359
1360                 if ( $res ) {
1361                         $row = $this->fetchRow( $res );
1362                         $rows = ( isset( $row['rowcount'] ) ) ? (int)$row['rowcount'] : 0;
1363                 }
1364
1365                 return $rows;
1366         }
1367
1368         /**
1369          * Removes most variables from an SQL query and replaces them with X or N for numbers.
1370          * It's only slightly flawed. Don't use for anything important.
1371          *
1372          * @param string $sql A SQL Query
1373          *
1374          * @return string
1375          */
1376         protected static function generalizeSQL( $sql ) {
1377                 # This does the same as the regexp below would do, but in such a way
1378                 # as to avoid crashing php on some large strings.
1379                 # $sql = preg_replace( "/'([^\\\\']|\\\\.)*'|\"([^\\\\\"]|\\\\.)*\"/", "'X'", $sql );
1380
1381                 $sql = str_replace( "\\\\", '', $sql );
1382                 $sql = str_replace( "\\'", '', $sql );
1383                 $sql = str_replace( "\\\"", '', $sql );
1384                 $sql = preg_replace( "/'.*'/s", "'X'", $sql );
1385                 $sql = preg_replace( '/".*"/s', "'X'", $sql );
1386
1387                 # All newlines, tabs, etc replaced by single space
1388                 $sql = preg_replace( '/\s+/', ' ', $sql );
1389
1390                 # All numbers => N,
1391                 # except the ones surrounded by characters, e.g. l10n
1392                 $sql = preg_replace( '/-?\d+(,-?\d+)+/s', 'N,...,N', $sql );
1393                 $sql = preg_replace( '/(?<![a-zA-Z])-?\d+(?![a-zA-Z])/s', 'N', $sql );
1394
1395                 return $sql;
1396         }
1397
1398         public function fieldExists( $table, $field, $fname = __METHOD__ ) {
1399                 $info = $this->fieldInfo( $table, $field );
1400
1401                 return (bool)$info;
1402         }
1403
1404         public function indexExists( $table, $index, $fname = __METHOD__ ) {
1405                 if ( !$this->tableExists( $table ) ) {
1406                         return null;
1407                 }
1408
1409                 $info = $this->indexInfo( $table, $index, $fname );
1410                 if ( is_null( $info ) ) {
1411                         return null;
1412                 } else {
1413                         return $info !== false;
1414                 }
1415         }
1416
1417         public function tableExists( $table, $fname = __METHOD__ ) {
1418                 $tableRaw = $this->tableName( $table, 'raw' );
1419                 if ( isset( $this->mSessionTempTables[$tableRaw] ) ) {
1420                         return true; // already known to exist
1421                 }
1422
1423                 $table = $this->tableName( $table );
1424                 $ignoreErrors = true;
1425                 $res = $this->query( "SELECT 1 FROM $table LIMIT 1", $fname, $ignoreErrors );
1426
1427                 return (bool)$res;
1428         }
1429
1430         public function indexUnique( $table, $index ) {
1431                 $indexInfo = $this->indexInfo( $table, $index );
1432
1433                 if ( !$indexInfo ) {
1434                         return null;
1435                 }
1436
1437                 return !$indexInfo[0]->Non_unique;
1438         }
1439
1440         /**
1441          * Helper for Database::insert().
1442          *
1443          * @param array $options
1444          * @return string
1445          */
1446         protected function makeInsertOptions( $options ) {
1447                 return implode( ' ', $options );
1448         }
1449
1450         public function insert( $table, $a, $fname = __METHOD__, $options = [] ) {
1451                 # No rows to insert, easy just return now
1452                 if ( !count( $a ) ) {
1453                         return true;
1454                 }
1455
1456                 $table = $this->tableName( $table );
1457
1458                 if ( !is_array( $options ) ) {
1459                         $options = [ $options ];
1460                 }
1461
1462                 $fh = null;
1463                 if ( isset( $options['fileHandle'] ) ) {
1464                         $fh = $options['fileHandle'];
1465                 }
1466                 $options = $this->makeInsertOptions( $options );
1467
1468                 if ( isset( $a[0] ) && is_array( $a[0] ) ) {
1469                         $multi = true;
1470                         $keys = array_keys( $a[0] );
1471                 } else {
1472                         $multi = false;
1473                         $keys = array_keys( $a );
1474                 }
1475
1476                 $sql = 'INSERT ' . $options .
1477                         " INTO $table (" . implode( ',', $keys ) . ') VALUES ';
1478
1479                 if ( $multi ) {
1480                         $first = true;
1481                         foreach ( $a as $row ) {
1482                                 if ( $first ) {
1483                                         $first = false;
1484                                 } else {
1485                                         $sql .= ',';
1486                                 }
1487                                 $sql .= '(' . $this->makeList( $row ) . ')';
1488                         }
1489                 } else {
1490                         $sql .= '(' . $this->makeList( $a ) . ')';
1491                 }
1492
1493                 if ( $fh !== null && false === fwrite( $fh, $sql ) ) {
1494                         return false;
1495                 } elseif ( $fh !== null ) {
1496                         return true;
1497                 }
1498
1499                 return (bool)$this->query( $sql, $fname );
1500         }
1501
1502         /**
1503          * Make UPDATE options array for Database::makeUpdateOptions
1504          *
1505          * @param array $options
1506          * @return array
1507          */
1508         protected function makeUpdateOptionsArray( $options ) {
1509                 if ( !is_array( $options ) ) {
1510                         $options = [ $options ];
1511                 }
1512
1513                 $opts = [];
1514
1515                 if ( in_array( 'IGNORE', $options ) ) {
1516                         $opts[] = 'IGNORE';
1517                 }
1518
1519                 return $opts;
1520         }
1521
1522         /**
1523          * Make UPDATE options for the Database::update function
1524          *
1525          * @param array $options The options passed to Database::update
1526          * @return string
1527          */
1528         protected function makeUpdateOptions( $options ) {
1529                 $opts = $this->makeUpdateOptionsArray( $options );
1530
1531                 return implode( ' ', $opts );
1532         }
1533
1534         public function update( $table, $values, $conds, $fname = __METHOD__, $options = [] ) {
1535                 $table = $this->tableName( $table );
1536                 $opts = $this->makeUpdateOptions( $options );
1537                 $sql = "UPDATE $opts $table SET " . $this->makeList( $values, self::LIST_SET );
1538
1539                 if ( $conds !== [] && $conds !== '*' ) {
1540                         $sql .= " WHERE " . $this->makeList( $conds, self::LIST_AND );
1541                 }
1542
1543                 return $this->query( $sql, $fname );
1544         }
1545
1546         public function makeList( $a, $mode = self::LIST_COMMA ) {
1547                 if ( !is_array( $a ) ) {
1548                         throw new DBUnexpectedError( $this, __METHOD__ . ' called with incorrect parameters' );
1549                 }
1550
1551                 $first = true;
1552                 $list = '';
1553
1554                 foreach ( $a as $field => $value ) {
1555                         if ( !$first ) {
1556                                 if ( $mode == self::LIST_AND ) {
1557                                         $list .= ' AND ';
1558                                 } elseif ( $mode == self::LIST_OR ) {
1559                                         $list .= ' OR ';
1560                                 } else {
1561                                         $list .= ',';
1562                                 }
1563                         } else {
1564                                 $first = false;
1565                         }
1566
1567                         if ( ( $mode == self::LIST_AND || $mode == self::LIST_OR ) && is_numeric( $field ) ) {
1568                                 $list .= "($value)";
1569                         } elseif ( $mode == self::LIST_SET && is_numeric( $field ) ) {
1570                                 $list .= "$value";
1571                         } elseif (
1572                                 ( $mode == self::LIST_AND || $mode == self::LIST_OR ) && is_array( $value )
1573                         ) {
1574                                 // Remove null from array to be handled separately if found
1575                                 $includeNull = false;
1576                                 foreach ( array_keys( $value, null, true ) as $nullKey ) {
1577                                         $includeNull = true;
1578                                         unset( $value[$nullKey] );
1579                                 }
1580                                 if ( count( $value ) == 0 && !$includeNull ) {
1581                                         throw new InvalidArgumentException(
1582                                                 __METHOD__ . ": empty input for field $field" );
1583                                 } elseif ( count( $value ) == 0 ) {
1584                                         // only check if $field is null
1585                                         $list .= "$field IS NULL";
1586                                 } else {
1587                                         // IN clause contains at least one valid element
1588                                         if ( $includeNull ) {
1589                                                 // Group subconditions to ensure correct precedence
1590                                                 $list .= '(';
1591                                         }
1592                                         if ( count( $value ) == 1 ) {
1593                                                 // Special-case single values, as IN isn't terribly efficient
1594                                                 // Don't necessarily assume the single key is 0; we don't
1595                                                 // enforce linear numeric ordering on other arrays here.
1596                                                 $value = array_values( $value )[0];
1597                                                 $list .= $field . " = " . $this->addQuotes( $value );
1598                                         } else {
1599                                                 $list .= $field . " IN (" . $this->makeList( $value ) . ") ";
1600                                         }
1601                                         // if null present in array, append IS NULL
1602                                         if ( $includeNull ) {
1603                                                 $list .= " OR $field IS NULL)";
1604                                         }
1605                                 }
1606                         } elseif ( $value === null ) {
1607                                 if ( $mode == self::LIST_AND || $mode == self::LIST_OR ) {
1608                                         $list .= "$field IS ";
1609                                 } elseif ( $mode == self::LIST_SET ) {
1610                                         $list .= "$field = ";
1611                                 }
1612                                 $list .= 'NULL';
1613                         } else {
1614                                 if (
1615                                         $mode == self::LIST_AND || $mode == self::LIST_OR || $mode == self::LIST_SET
1616                                 ) {
1617                                         $list .= "$field = ";
1618                                 }
1619                                 $list .= $mode == self::LIST_NAMES ? $value : $this->addQuotes( $value );
1620                         }
1621                 }
1622
1623                 return $list;
1624         }
1625
1626         public function makeWhereFrom2d( $data, $baseKey, $subKey ) {
1627                 $conds = [];
1628
1629                 foreach ( $data as $base => $sub ) {
1630                         if ( count( $sub ) ) {
1631                                 $conds[] = $this->makeList(
1632                                         [ $baseKey => $base, $subKey => array_keys( $sub ) ],
1633                                         self::LIST_AND );
1634                         }
1635                 }
1636
1637                 if ( $conds ) {
1638                         return $this->makeList( $conds, self::LIST_OR );
1639                 } else {
1640                         // Nothing to search for...
1641                         return false;
1642                 }
1643         }
1644
1645         public function aggregateValue( $valuedata, $valuename = 'value' ) {
1646                 return $valuename;
1647         }
1648
1649         public function bitNot( $field ) {
1650                 return "(~$field)";
1651         }
1652
1653         public function bitAnd( $fieldLeft, $fieldRight ) {
1654                 return "($fieldLeft & $fieldRight)";
1655         }
1656
1657         public function bitOr( $fieldLeft, $fieldRight ) {
1658                 return "($fieldLeft | $fieldRight)";
1659         }
1660
1661         public function buildConcat( $stringList ) {
1662                 return 'CONCAT(' . implode( ',', $stringList ) . ')';
1663         }
1664
1665         public function buildGroupConcatField(
1666                 $delim, $table, $field, $conds = '', $join_conds = []
1667         ) {
1668                 $fld = "GROUP_CONCAT($field SEPARATOR " . $this->addQuotes( $delim ) . ')';
1669
1670                 return '(' . $this->selectSQLText( $table, $fld, $conds, null, [], $join_conds ) . ')';
1671         }
1672
1673         public function buildStringCast( $field ) {
1674                 return $field;
1675         }
1676
1677         public function selectDB( $db ) {
1678                 # Stub. Shouldn't cause serious problems if it's not overridden, but
1679                 # if your database engine supports a concept similar to MySQL's
1680                 # databases you may as well.
1681                 $this->mDBname = $db;
1682
1683                 return true;
1684         }
1685
1686         public function getDBname() {
1687                 return $this->mDBname;
1688         }
1689
1690         public function getServer() {
1691                 return $this->mServer;
1692         }
1693
1694         public function tableName( $name, $format = 'quoted' ) {
1695                 # Skip the entire process when we have a string quoted on both ends.
1696                 # Note that we check the end so that we will still quote any use of
1697                 # use of `database`.table. But won't break things if someone wants
1698                 # to query a database table with a dot in the name.
1699                 if ( $this->isQuotedIdentifier( $name ) ) {
1700                         return $name;
1701                 }
1702
1703                 # Lets test for any bits of text that should never show up in a table
1704                 # name. Basically anything like JOIN or ON which are actually part of
1705                 # SQL queries, but may end up inside of the table value to combine
1706                 # sql. Such as how the API is doing.
1707                 # Note that we use a whitespace test rather than a \b test to avoid
1708                 # any remote case where a word like on may be inside of a table name
1709                 # surrounded by symbols which may be considered word breaks.
1710                 if ( preg_match( '/(^|\s)(DISTINCT|JOIN|ON|AS)(\s|$)/i', $name ) !== 0 ) {
1711                         return $name;
1712                 }
1713
1714                 # Split database and table into proper variables.
1715                 # We reverse the explode so that database.table and table both output
1716                 # the correct table.
1717                 $dbDetails = explode( '.', $name, 3 );
1718                 if ( count( $dbDetails ) == 3 ) {
1719                         list( $database, $schema, $table ) = $dbDetails;
1720                         # We don't want any prefix added in this case
1721                         $prefix = '';
1722                 } elseif ( count( $dbDetails ) == 2 ) {
1723                         list( $database, $table ) = $dbDetails;
1724                         # We don't want any prefix added in this case
1725                         $prefix = '';
1726                         # In dbs that support it, $database may actually be the schema
1727                         # but that doesn't affect any of the functionality here
1728                         $schema = '';
1729                 } else {
1730                         list( $table ) = $dbDetails;
1731                         if ( isset( $this->tableAliases[$table] ) ) {
1732                                 $database = $this->tableAliases[$table]['dbname'];
1733                                 $schema = is_string( $this->tableAliases[$table]['schema'] )
1734                                         ? $this->tableAliases[$table]['schema']
1735                                         : $this->mSchema;
1736                                 $prefix = is_string( $this->tableAliases[$table]['prefix'] )
1737                                         ? $this->tableAliases[$table]['prefix']
1738                                         : $this->mTablePrefix;
1739                         } else {
1740                                 $database = '';
1741                                 $schema = $this->mSchema; # Default schema
1742                                 $prefix = $this->mTablePrefix; # Default prefix
1743                         }
1744                 }
1745
1746                 # Quote $table and apply the prefix if not quoted.
1747                 # $tableName might be empty if this is called from Database::replaceVars()
1748                 $tableName = "{$prefix}{$table}";
1749                 if ( $format === 'quoted'
1750                         && !$this->isQuotedIdentifier( $tableName )
1751                         && $tableName !== ''
1752                 ) {
1753                         $tableName = $this->addIdentifierQuotes( $tableName );
1754                 }
1755
1756                 # Quote $schema and $database and merge them with the table name if needed
1757                 $tableName = $this->prependDatabaseOrSchema( $schema, $tableName, $format );
1758                 $tableName = $this->prependDatabaseOrSchema( $database, $tableName, $format );
1759
1760                 return $tableName;
1761         }
1762
1763         /**
1764          * @param string|null $namespace Database or schema
1765          * @param string $relation Name of table, view, sequence, etc...
1766          * @param string $format One of (raw, quoted)
1767          * @return string Relation name with quoted and merged $namespace as needed
1768          */
1769         private function prependDatabaseOrSchema( $namespace, $relation, $format ) {
1770                 if ( strlen( $namespace ) ) {
1771                         if ( $format === 'quoted' && !$this->isQuotedIdentifier( $namespace ) ) {
1772                                 $namespace = $this->addIdentifierQuotes( $namespace );
1773                         }
1774                         $relation = $namespace . '.' . $relation;
1775                 }
1776
1777                 return $relation;
1778         }
1779
1780         public function tableNames() {
1781                 $inArray = func_get_args();
1782                 $retVal = [];
1783
1784                 foreach ( $inArray as $name ) {
1785                         $retVal[$name] = $this->tableName( $name );
1786                 }
1787
1788                 return $retVal;
1789         }
1790
1791         public function tableNamesN() {
1792                 $inArray = func_get_args();
1793                 $retVal = [];
1794
1795                 foreach ( $inArray as $name ) {
1796                         $retVal[] = $this->tableName( $name );
1797                 }
1798
1799                 return $retVal;
1800         }
1801
1802         /**
1803          * Get an aliased table name
1804          * e.g. tableName AS newTableName
1805          *
1806          * @param string $name Table name, see tableName()
1807          * @param string|bool $alias Alias (optional)
1808          * @return string SQL name for aliased table. Will not alias a table to its own name
1809          */
1810         protected function tableNameWithAlias( $name, $alias = false ) {
1811                 if ( !$alias || $alias == $name ) {
1812                         return $this->tableName( $name );
1813                 } else {
1814                         return $this->tableName( $name ) . ' ' . $this->addIdentifierQuotes( $alias );
1815                 }
1816         }
1817
1818         /**
1819          * Gets an array of aliased table names
1820          *
1821          * @param array $tables [ [alias] => table ]
1822          * @return string[] See tableNameWithAlias()
1823          */
1824         protected function tableNamesWithAlias( $tables ) {
1825                 $retval = [];
1826                 foreach ( $tables as $alias => $table ) {
1827                         if ( is_numeric( $alias ) ) {
1828                                 $alias = $table;
1829                         }
1830                         $retval[] = $this->tableNameWithAlias( $table, $alias );
1831                 }
1832
1833                 return $retval;
1834         }
1835
1836         /**
1837          * Get an aliased field name
1838          * e.g. fieldName AS newFieldName
1839          *
1840          * @param string $name Field name
1841          * @param string|bool $alias Alias (optional)
1842          * @return string SQL name for aliased field. Will not alias a field to its own name
1843          */
1844         protected function fieldNameWithAlias( $name, $alias = false ) {
1845                 if ( !$alias || (string)$alias === (string)$name ) {
1846                         return $name;
1847                 } else {
1848                         return $name . ' AS ' . $this->addIdentifierQuotes( $alias ); // PostgreSQL needs AS
1849                 }
1850         }
1851
1852         /**
1853          * Gets an array of aliased field names
1854          *
1855          * @param array $fields [ [alias] => field ]
1856          * @return string[] See fieldNameWithAlias()
1857          */
1858         protected function fieldNamesWithAlias( $fields ) {
1859                 $retval = [];
1860                 foreach ( $fields as $alias => $field ) {
1861                         if ( is_numeric( $alias ) ) {
1862                                 $alias = $field;
1863                         }
1864                         $retval[] = $this->fieldNameWithAlias( $field, $alias );
1865                 }
1866
1867                 return $retval;
1868         }
1869
1870         /**
1871          * Get the aliased table name clause for a FROM clause
1872          * which might have a JOIN and/or USE INDEX or IGNORE INDEX clause
1873          *
1874          * @param array $tables ( [alias] => table )
1875          * @param array $use_index Same as for select()
1876          * @param array $ignore_index Same as for select()
1877          * @param array $join_conds Same as for select()
1878          * @return string
1879          */
1880         protected function tableNamesWithIndexClauseOrJOIN(
1881                 $tables, $use_index = [], $ignore_index = [], $join_conds = []
1882         ) {
1883                 $ret = [];
1884                 $retJOIN = [];
1885                 $use_index = (array)$use_index;
1886                 $ignore_index = (array)$ignore_index;
1887                 $join_conds = (array)$join_conds;
1888
1889                 foreach ( $tables as $alias => $table ) {
1890                         if ( !is_string( $alias ) ) {
1891                                 // No alias? Set it equal to the table name
1892                                 $alias = $table;
1893                         }
1894                         // Is there a JOIN clause for this table?
1895                         if ( isset( $join_conds[$alias] ) ) {
1896                                 list( $joinType, $conds ) = $join_conds[$alias];
1897                                 $tableClause = $joinType;
1898                                 $tableClause .= ' ' . $this->tableNameWithAlias( $table, $alias );
1899                                 if ( isset( $use_index[$alias] ) ) { // has USE INDEX?
1900                                         $use = $this->useIndexClause( implode( ',', (array)$use_index[$alias] ) );
1901                                         if ( $use != '' ) {
1902                                                 $tableClause .= ' ' . $use;
1903                                         }
1904                                 }
1905                                 if ( isset( $ignore_index[$alias] ) ) { // has IGNORE INDEX?
1906                                         $ignore = $this->ignoreIndexClause(
1907                                                 implode( ',', (array)$ignore_index[$alias] ) );
1908                                         if ( $ignore != '' ) {
1909                                                 $tableClause .= ' ' . $ignore;
1910                                         }
1911                                 }
1912                                 $on = $this->makeList( (array)$conds, self::LIST_AND );
1913                                 if ( $on != '' ) {
1914                                         $tableClause .= ' ON (' . $on . ')';
1915                                 }
1916
1917                                 $retJOIN[] = $tableClause;
1918                         } elseif ( isset( $use_index[$alias] ) ) {
1919                                 // Is there an INDEX clause for this table?
1920                                 $tableClause = $this->tableNameWithAlias( $table, $alias );
1921                                 $tableClause .= ' ' . $this->useIndexClause(
1922                                                 implode( ',', (array)$use_index[$alias] )
1923                                         );
1924
1925                                 $ret[] = $tableClause;
1926                         } elseif ( isset( $ignore_index[$alias] ) ) {
1927                                 // Is there an INDEX clause for this table?
1928                                 $tableClause = $this->tableNameWithAlias( $table, $alias );
1929                                 $tableClause .= ' ' . $this->ignoreIndexClause(
1930                                                 implode( ',', (array)$ignore_index[$alias] )
1931                                         );
1932
1933                                 $ret[] = $tableClause;
1934                         } else {
1935                                 $tableClause = $this->tableNameWithAlias( $table, $alias );
1936
1937                                 $ret[] = $tableClause;
1938                         }
1939                 }
1940
1941                 // We can't separate explicit JOIN clauses with ',', use ' ' for those
1942                 $implicitJoins = !empty( $ret ) ? implode( ',', $ret ) : "";
1943                 $explicitJoins = !empty( $retJOIN ) ? implode( ' ', $retJOIN ) : "";
1944
1945                 // Compile our final table clause
1946                 return implode( ' ', [ $implicitJoins, $explicitJoins ] );
1947         }
1948
1949         /**
1950          * Get the name of an index in a given table.
1951          *
1952          * @param string $index
1953          * @return string
1954          */
1955         protected function indexName( $index ) {
1956                 return $index;
1957         }
1958
1959         public function addQuotes( $s ) {
1960                 if ( $s instanceof Blob ) {
1961                         $s = $s->fetch();
1962                 }
1963                 if ( $s === null ) {
1964                         return 'NULL';
1965                 } elseif ( is_bool( $s ) ) {
1966                         return (int)$s;
1967                 } else {
1968                         # This will also quote numeric values. This should be harmless,
1969                         # and protects against weird problems that occur when they really
1970                         # _are_ strings such as article titles and string->number->string
1971                         # conversion is not 1:1.
1972                         return "'" . $this->strencode( $s ) . "'";
1973                 }
1974         }
1975
1976         /**
1977          * Quotes an identifier using `backticks` or "double quotes" depending on the database type.
1978          * MySQL uses `backticks` while basically everything else uses double quotes.
1979          * Since MySQL is the odd one out here the double quotes are our generic
1980          * and we implement backticks in DatabaseMysql.
1981          *
1982          * @param string $s
1983          * @return string
1984          */
1985         public function addIdentifierQuotes( $s ) {
1986                 return '"' . str_replace( '"', '""', $s ) . '"';
1987         }
1988
1989         /**
1990          * Returns if the given identifier looks quoted or not according to
1991          * the database convention for quoting identifiers .
1992          *
1993          * @note Do not use this to determine if untrusted input is safe.
1994          *   A malicious user can trick this function.
1995          * @param string $name
1996          * @return bool
1997          */
1998         public function isQuotedIdentifier( $name ) {
1999                 return $name[0] == '"' && substr( $name, -1, 1 ) == '"';
2000         }
2001
2002         /**
2003          * @param string $s
2004          * @return string
2005          */
2006         protected function escapeLikeInternal( $s ) {
2007                 return addcslashes( $s, '\%_' );
2008         }
2009
2010         public function buildLike() {
2011                 $params = func_get_args();
2012
2013                 if ( count( $params ) > 0 && is_array( $params[0] ) ) {
2014                         $params = $params[0];
2015                 }
2016
2017                 $s = '';
2018
2019                 foreach ( $params as $value ) {
2020                         if ( $value instanceof LikeMatch ) {
2021                                 $s .= $value->toString();
2022                         } else {
2023                                 $s .= $this->escapeLikeInternal( $value );
2024                         }
2025                 }
2026
2027                 return " LIKE {$this->addQuotes( $s )} ";
2028         }
2029
2030         public function anyChar() {
2031                 return new LikeMatch( '_' );
2032         }
2033
2034         public function anyString() {
2035                 return new LikeMatch( '%' );
2036         }
2037
2038         public function nextSequenceValue( $seqName ) {
2039                 return null;
2040         }
2041
2042         /**
2043          * USE INDEX clause. Unlikely to be useful for anything but MySQL. This
2044          * is only needed because a) MySQL must be as efficient as possible due to
2045          * its use on Wikipedia, and b) MySQL 4.0 is kind of dumb sometimes about
2046          * which index to pick. Anyway, other databases might have different
2047          * indexes on a given table. So don't bother overriding this unless you're
2048          * MySQL.
2049          * @param string $index
2050          * @return string
2051          */
2052         public function useIndexClause( $index ) {
2053                 return '';
2054         }
2055
2056         /**
2057          * IGNORE INDEX clause. Unlikely to be useful for anything but MySQL. This
2058          * is only needed because a) MySQL must be as efficient as possible due to
2059          * its use on Wikipedia, and b) MySQL 4.0 is kind of dumb sometimes about
2060          * which index to pick. Anyway, other databases might have different
2061          * indexes on a given table. So don't bother overriding this unless you're
2062          * MySQL.
2063          * @param string $index
2064          * @return string
2065          */
2066         public function ignoreIndexClause( $index ) {
2067                 return '';
2068         }
2069
2070         public function replace( $table, $uniqueIndexes, $rows, $fname = __METHOD__ ) {
2071                 $quotedTable = $this->tableName( $table );
2072
2073                 if ( count( $rows ) == 0 ) {
2074                         return;
2075                 }
2076
2077                 # Single row case
2078                 if ( !is_array( reset( $rows ) ) ) {
2079                         $rows = [ $rows ];
2080                 }
2081
2082                 // @FXIME: this is not atomic, but a trx would break affectedRows()
2083                 foreach ( $rows as $row ) {
2084                         # Delete rows which collide
2085                         if ( $uniqueIndexes ) {
2086                                 $sql = "DELETE FROM $quotedTable WHERE ";
2087                                 $first = true;
2088                                 foreach ( $uniqueIndexes as $index ) {
2089                                         if ( $first ) {
2090                                                 $first = false;
2091                                                 $sql .= '( ';
2092                                         } else {
2093                                                 $sql .= ' ) OR ( ';
2094                                         }
2095                                         if ( is_array( $index ) ) {
2096                                                 $first2 = true;
2097                                                 foreach ( $index as $col ) {
2098                                                         if ( $first2 ) {
2099                                                                 $first2 = false;
2100                                                         } else {
2101                                                                 $sql .= ' AND ';
2102                                                         }
2103                                                         $sql .= $col . '=' . $this->addQuotes( $row[$col] );
2104                                                 }
2105                                         } else {
2106                                                 $sql .= $index . '=' . $this->addQuotes( $row[$index] );
2107                                         }
2108                                 }
2109                                 $sql .= ' )';
2110                                 $this->query( $sql, $fname );
2111                         }
2112
2113                         # Now insert the row
2114                         $this->insert( $table, $row, $fname );
2115                 }
2116         }
2117
2118         /**
2119          * REPLACE query wrapper for MySQL and SQLite, which have a native REPLACE
2120          * statement.
2121          *
2122          * @param string $table Table name
2123          * @param array|string $rows Row(s) to insert
2124          * @param string $fname Caller function name
2125          *
2126          * @return ResultWrapper
2127          */
2128         protected function nativeReplace( $table, $rows, $fname ) {
2129                 $table = $this->tableName( $table );
2130
2131                 # Single row case
2132                 if ( !is_array( reset( $rows ) ) ) {
2133                         $rows = [ $rows ];
2134                 }
2135
2136                 $sql = "REPLACE INTO $table (" . implode( ',', array_keys( $rows[0] ) ) . ') VALUES ';
2137                 $first = true;
2138
2139                 foreach ( $rows as $row ) {
2140                         if ( $first ) {
2141                                 $first = false;
2142                         } else {
2143                                 $sql .= ',';
2144                         }
2145
2146                         $sql .= '(' . $this->makeList( $row ) . ')';
2147                 }
2148
2149                 return $this->query( $sql, $fname );
2150         }
2151
2152         public function upsert( $table, array $rows, array $uniqueIndexes, array $set,
2153                 $fname = __METHOD__
2154         ) {
2155                 if ( !count( $rows ) ) {
2156                         return true; // nothing to do
2157                 }
2158
2159                 if ( !is_array( reset( $rows ) ) ) {
2160                         $rows = [ $rows ];
2161                 }
2162
2163                 if ( count( $uniqueIndexes ) ) {
2164                         $clauses = []; // list WHERE clauses that each identify a single row
2165                         foreach ( $rows as $row ) {
2166                                 foreach ( $uniqueIndexes as $index ) {
2167                                         $index = is_array( $index ) ? $index : [ $index ]; // columns
2168                                         $rowKey = []; // unique key to this row
2169                                         foreach ( $index as $column ) {
2170                                                 $rowKey[$column] = $row[$column];
2171                                         }
2172                                         $clauses[] = $this->makeList( $rowKey, self::LIST_AND );
2173                                 }
2174                         }
2175                         $where = [ $this->makeList( $clauses, self::LIST_OR ) ];
2176                 } else {
2177                         $where = false;
2178                 }
2179
2180                 $useTrx = !$this->mTrxLevel;
2181                 if ( $useTrx ) {
2182                         $this->begin( $fname, self::TRANSACTION_INTERNAL );
2183                 }
2184                 try {
2185                         # Update any existing conflicting row(s)
2186                         if ( $where !== false ) {
2187                                 $ok = $this->update( $table, $set, $where, $fname );
2188                         } else {
2189                                 $ok = true;
2190                         }
2191                         # Now insert any non-conflicting row(s)
2192                         $ok = $this->insert( $table, $rows, $fname, [ 'IGNORE' ] ) && $ok;
2193                 } catch ( Exception $e ) {
2194                         if ( $useTrx ) {
2195                                 $this->rollback( $fname, self::FLUSHING_INTERNAL );
2196                         }
2197                         throw $e;
2198                 }
2199                 if ( $useTrx ) {
2200                         $this->commit( $fname, self::FLUSHING_INTERNAL );
2201                 }
2202
2203                 return $ok;
2204         }
2205
2206         public function deleteJoin( $delTable, $joinTable, $delVar, $joinVar, $conds,
2207                 $fname = __METHOD__
2208         ) {
2209                 if ( !$conds ) {
2210                         throw new DBUnexpectedError( $this, __METHOD__ . ' called with empty $conds' );
2211                 }
2212
2213                 $delTable = $this->tableName( $delTable );
2214                 $joinTable = $this->tableName( $joinTable );
2215                 $sql = "DELETE FROM $delTable WHERE $delVar IN (SELECT $joinVar FROM $joinTable ";
2216                 if ( $conds != '*' ) {
2217                         $sql .= 'WHERE ' . $this->makeList( $conds, self::LIST_AND );
2218                 }
2219                 $sql .= ')';
2220
2221                 $this->query( $sql, $fname );
2222         }
2223
2224         public function textFieldSize( $table, $field ) {
2225                 $table = $this->tableName( $table );
2226                 $sql = "SHOW COLUMNS FROM $table LIKE \"$field\";";
2227                 $res = $this->query( $sql, __METHOD__ );
2228                 $row = $this->fetchObject( $res );
2229
2230                 $m = [];
2231
2232                 if ( preg_match( '/\((.*)\)/', $row->Type, $m ) ) {
2233                         $size = $m[1];
2234                 } else {
2235                         $size = -1;
2236                 }
2237
2238                 return $size;
2239         }
2240
2241         public function delete( $table, $conds, $fname = __METHOD__ ) {
2242                 if ( !$conds ) {
2243                         throw new DBUnexpectedError( $this, __METHOD__ . ' called with no conditions' );
2244                 }
2245
2246                 $table = $this->tableName( $table );
2247                 $sql = "DELETE FROM $table";
2248
2249                 if ( $conds != '*' ) {
2250                         if ( is_array( $conds ) ) {
2251                                 $conds = $this->makeList( $conds, self::LIST_AND );
2252                         }
2253                         $sql .= ' WHERE ' . $conds;
2254                 }
2255
2256                 return $this->query( $sql, $fname );
2257         }
2258
2259         public function insertSelect(
2260                 $destTable, $srcTable, $varMap, $conds,
2261                 $fname = __METHOD__, $insertOptions = [], $selectOptions = []
2262         ) {
2263                 if ( $this->cliMode ) {
2264                         // For massive migrations with downtime, we don't want to select everything
2265                         // into memory and OOM, so do all this native on the server side if possible.
2266                         return $this->nativeInsertSelect(
2267                                 $destTable,
2268                                 $srcTable,
2269                                 $varMap,
2270                                 $conds,
2271                                 $fname,
2272                                 $insertOptions,
2273                                 $selectOptions
2274                         );
2275                 }
2276
2277                 // For web requests, do a locking SELECT and then INSERT. This puts the SELECT burden
2278                 // on only the master (without needing row-based-replication). It also makes it easy to
2279                 // know how big the INSERT is going to be.
2280                 $fields = [];
2281                 foreach ( $varMap as $dstColumn => $sourceColumnOrSql ) {
2282                         $fields[] = $this->fieldNameWithAlias( $sourceColumnOrSql, $dstColumn );
2283                 }
2284                 $selectOptions[] = 'FOR UPDATE';
2285                 $res = $this->select( $srcTable, implode( ',', $fields ), $conds, $fname, $selectOptions );
2286                 if ( !$res ) {
2287                         return false;
2288                 }
2289
2290                 $rows = [];
2291                 foreach ( $res as $row ) {
2292                         $rows[] = (array)$row;
2293                 }
2294
2295                 return $this->insert( $destTable, $rows, $fname, $insertOptions );
2296         }
2297
2298         protected function nativeInsertSelect( $destTable, $srcTable, $varMap, $conds,
2299                 $fname = __METHOD__,
2300                 $insertOptions = [], $selectOptions = []
2301         ) {
2302                 $destTable = $this->tableName( $destTable );
2303
2304                 if ( !is_array( $insertOptions ) ) {
2305                         $insertOptions = [ $insertOptions ];
2306                 }
2307
2308                 $insertOptions = $this->makeInsertOptions( $insertOptions );
2309
2310                 if ( !is_array( $selectOptions ) ) {
2311                         $selectOptions = [ $selectOptions ];
2312                 }
2313
2314                 list( $startOpts, $useIndex, $tailOpts, $ignoreIndex ) = $this->makeSelectOptions(
2315                         $selectOptions );
2316
2317                 if ( is_array( $srcTable ) ) {
2318                         $srcTable = implode( ',', array_map( [ $this, 'tableName' ], $srcTable ) );
2319                 } else {
2320                         $srcTable = $this->tableName( $srcTable );
2321                 }
2322
2323                 $sql = "INSERT $insertOptions" .
2324                         " INTO $destTable (" . implode( ',', array_keys( $varMap ) ) . ')' .
2325                         " SELECT $startOpts " . implode( ',', $varMap ) .
2326                         " FROM $srcTable $useIndex $ignoreIndex ";
2327
2328                 if ( $conds != '*' ) {
2329                         if ( is_array( $conds ) ) {
2330                                 $conds = $this->makeList( $conds, self::LIST_AND );
2331                         }
2332                         $sql .= " WHERE $conds";
2333                 }
2334
2335                 $sql .= " $tailOpts";
2336
2337                 return $this->query( $sql, $fname );
2338         }
2339
2340         /**
2341          * Construct a LIMIT query with optional offset. This is used for query
2342          * pages. The SQL should be adjusted so that only the first $limit rows
2343          * are returned. If $offset is provided as well, then the first $offset
2344          * rows should be discarded, and the next $limit rows should be returned.
2345          * If the result of the query is not ordered, then the rows to be returned
2346          * are theoretically arbitrary.
2347          *
2348          * $sql is expected to be a SELECT, if that makes a difference.
2349          *
2350          * The version provided by default works in MySQL and SQLite. It will very
2351          * likely need to be overridden for most other DBMSes.
2352          *
2353          * @param string $sql SQL query we will append the limit too
2354          * @param int $limit The SQL limit
2355          * @param int|bool $offset The SQL offset (default false)
2356          * @throws DBUnexpectedError
2357          * @return string
2358          */
2359         public function limitResult( $sql, $limit, $offset = false ) {
2360                 if ( !is_numeric( $limit ) ) {
2361                         throw new DBUnexpectedError( $this,
2362                                 "Invalid non-numeric limit passed to limitResult()\n" );
2363                 }
2364
2365                 return "$sql LIMIT "
2366                 . ( ( is_numeric( $offset ) && $offset != 0 ) ? "{$offset}," : "" )
2367                 . "{$limit} ";
2368         }
2369
2370         public function unionSupportsOrderAndLimit() {
2371                 return true; // True for almost every DB supported
2372         }
2373
2374         public function unionQueries( $sqls, $all ) {
2375                 $glue = $all ? ') UNION ALL (' : ') UNION (';
2376
2377                 return '(' . implode( $glue, $sqls ) . ')';
2378         }
2379
2380         public function conditional( $cond, $trueVal, $falseVal ) {
2381                 if ( is_array( $cond ) ) {
2382                         $cond = $this->makeList( $cond, self::LIST_AND );
2383                 }
2384
2385                 return " (CASE WHEN $cond THEN $trueVal ELSE $falseVal END) ";
2386         }
2387
2388         public function strreplace( $orig, $old, $new ) {
2389                 return "REPLACE({$orig}, {$old}, {$new})";
2390         }
2391
2392         public function getServerUptime() {
2393                 return 0;
2394         }
2395
2396         public function wasDeadlock() {
2397                 return false;
2398         }
2399
2400         public function wasLockTimeout() {
2401                 return false;
2402         }
2403
2404         public function wasErrorReissuable() {
2405                 return false;
2406         }
2407
2408         public function wasReadOnlyError() {
2409                 return false;
2410         }
2411
2412         /**
2413          * Do not use this method outside of Database/DBError classes
2414          *
2415          * @param integer|string $errno
2416          * @return bool Whether the given query error was a connection drop
2417          */
2418         public function wasConnectionError( $errno ) {
2419                 return false;
2420         }
2421
2422         public function deadlockLoop() {
2423                 $args = func_get_args();
2424                 $function = array_shift( $args );
2425                 $tries = self::DEADLOCK_TRIES;
2426
2427                 $this->begin( __METHOD__ );
2428
2429                 $retVal = null;
2430                 /** @var Exception $e */
2431                 $e = null;
2432                 do {
2433                         try {
2434                                 $retVal = call_user_func_array( $function, $args );
2435                                 break;
2436                         } catch ( DBQueryError $e ) {
2437                                 if ( $this->wasDeadlock() ) {
2438                                         // Retry after a randomized delay
2439                                         usleep( mt_rand( self::DEADLOCK_DELAY_MIN, self::DEADLOCK_DELAY_MAX ) );
2440                                 } else {
2441                                         // Throw the error back up
2442                                         throw $e;
2443                                 }
2444                         }
2445                 } while ( --$tries > 0 );
2446
2447                 if ( $tries <= 0 ) {
2448                         // Too many deadlocks; give up
2449                         $this->rollback( __METHOD__ );
2450                         throw $e;
2451                 } else {
2452                         $this->commit( __METHOD__ );
2453
2454                         return $retVal;
2455                 }
2456         }
2457
2458         public function masterPosWait( DBMasterPos $pos, $timeout ) {
2459                 # Real waits are implemented in the subclass.
2460                 return 0;
2461         }
2462
2463         public function getReplicaPos() {
2464                 # Stub
2465                 return false;
2466         }
2467
2468         public function getMasterPos() {
2469                 # Stub
2470                 return false;
2471         }
2472
2473         public function serverIsReadOnly() {
2474                 return false;
2475         }
2476
2477         final public function onTransactionResolution( callable $callback, $fname = __METHOD__ ) {
2478                 if ( !$this->mTrxLevel ) {
2479                         throw new DBUnexpectedError( $this, "No transaction is active." );
2480                 }
2481                 $this->mTrxEndCallbacks[] = [ $callback, $fname ];
2482         }
2483
2484         final public function onTransactionIdle( callable $callback, $fname = __METHOD__ ) {
2485                 $this->mTrxIdleCallbacks[] = [ $callback, $fname ];
2486                 if ( !$this->mTrxLevel ) {
2487                         $this->runOnTransactionIdleCallbacks( self::TRIGGER_IDLE );
2488                 }
2489         }
2490
2491         final public function onTransactionPreCommitOrIdle( callable $callback, $fname = __METHOD__ ) {
2492                 if ( $this->mTrxLevel ) {
2493                         $this->mTrxPreCommitCallbacks[] = [ $callback, $fname ];
2494                 } else {
2495                         // If no transaction is active, then make one for this callback
2496                         $this->startAtomic( __METHOD__ );
2497                         try {
2498                                 call_user_func( $callback );
2499                                 $this->endAtomic( __METHOD__ );
2500                         } catch ( Exception $e ) {
2501                                 $this->rollback( __METHOD__, self::FLUSHING_INTERNAL );
2502                                 throw $e;
2503                         }
2504                 }
2505         }
2506
2507         final public function setTransactionListener( $name, callable $callback = null ) {
2508                 if ( $callback ) {
2509                         $this->mTrxRecurringCallbacks[$name] = $callback;
2510                 } else {
2511                         unset( $this->mTrxRecurringCallbacks[$name] );
2512                 }
2513         }
2514
2515         /**
2516          * Whether to disable running of post-COMMIT/ROLLBACK callbacks
2517          *
2518          * This method should not be used outside of Database/LoadBalancer
2519          *
2520          * @param bool $suppress
2521          * @since 1.28
2522          */
2523         final public function setTrxEndCallbackSuppression( $suppress ) {
2524                 $this->mTrxEndCallbacksSuppressed = $suppress;
2525         }
2526
2527         /**
2528          * Actually run and consume any "on transaction idle/resolution" callbacks.
2529          *
2530          * This method should not be used outside of Database/LoadBalancer
2531          *
2532          * @param integer $trigger IDatabase::TRIGGER_* constant
2533          * @since 1.20
2534          * @throws Exception
2535          */
2536         public function runOnTransactionIdleCallbacks( $trigger ) {
2537                 if ( $this->mTrxEndCallbacksSuppressed ) {
2538                         return;
2539                 }
2540
2541                 $autoTrx = $this->getFlag( self::DBO_TRX ); // automatic begin() enabled?
2542                 /** @var Exception $e */
2543                 $e = null; // first exception
2544                 do { // callbacks may add callbacks :)
2545                         $callbacks = array_merge(
2546                                 $this->mTrxIdleCallbacks,
2547                                 $this->mTrxEndCallbacks // include "transaction resolution" callbacks
2548                         );
2549                         $this->mTrxIdleCallbacks = []; // consumed (and recursion guard)
2550                         $this->mTrxEndCallbacks = []; // consumed (recursion guard)
2551                         foreach ( $callbacks as $callback ) {
2552                                 try {
2553                                         list( $phpCallback ) = $callback;
2554                                         $this->clearFlag( self::DBO_TRX ); // make each query its own transaction
2555                                         call_user_func_array( $phpCallback, [ $trigger ] );
2556                                         if ( $autoTrx ) {
2557                                                 $this->setFlag( self::DBO_TRX ); // restore automatic begin()
2558                                         } else {
2559                                                 $this->clearFlag( self::DBO_TRX ); // restore auto-commit
2560                                         }
2561                                 } catch ( Exception $ex ) {
2562                                         call_user_func( $this->errorLogger, $ex );
2563                                         $e = $e ?: $ex;
2564                                         // Some callbacks may use startAtomic/endAtomic, so make sure
2565                                         // their transactions are ended so other callbacks don't fail
2566                                         if ( $this->trxLevel() ) {
2567                                                 $this->rollback( __METHOD__, self::FLUSHING_INTERNAL );
2568                                         }
2569                                 }
2570                         }
2571                 } while ( count( $this->mTrxIdleCallbacks ) );
2572
2573                 if ( $e instanceof Exception ) {
2574                         throw $e; // re-throw any first exception
2575                 }
2576         }
2577
2578         /**
2579          * Actually run and consume any "on transaction pre-commit" callbacks.
2580          *
2581          * This method should not be used outside of Database/LoadBalancer
2582          *
2583          * @since 1.22
2584          * @throws Exception
2585          */
2586         public function runOnTransactionPreCommitCallbacks() {
2587                 $e = null; // first exception
2588                 do { // callbacks may add callbacks :)
2589                         $callbacks = $this->mTrxPreCommitCallbacks;
2590                         $this->mTrxPreCommitCallbacks = []; // consumed (and recursion guard)
2591                         foreach ( $callbacks as $callback ) {
2592                                 try {
2593                                         list( $phpCallback ) = $callback;
2594                                         call_user_func( $phpCallback );
2595                                 } catch ( Exception $ex ) {
2596                                         call_user_func( $this->errorLogger, $ex );
2597                                         $e = $e ?: $ex;
2598                                 }
2599                         }
2600                 } while ( count( $this->mTrxPreCommitCallbacks ) );
2601
2602                 if ( $e instanceof Exception ) {
2603                         throw $e; // re-throw any first exception
2604                 }
2605         }
2606
2607         /**
2608          * Actually run any "transaction listener" callbacks.
2609          *
2610          * This method should not be used outside of Database/LoadBalancer
2611          *
2612          * @param integer $trigger IDatabase::TRIGGER_* constant
2613          * @throws Exception
2614          * @since 1.20
2615          */
2616         public function runTransactionListenerCallbacks( $trigger ) {
2617                 if ( $this->mTrxEndCallbacksSuppressed ) {
2618                         return;
2619                 }
2620
2621                 /** @var Exception $e */
2622                 $e = null; // first exception
2623
2624                 foreach ( $this->mTrxRecurringCallbacks as $phpCallback ) {
2625                         try {
2626                                 $phpCallback( $trigger, $this );
2627                         } catch ( Exception $ex ) {
2628                                 call_user_func( $this->errorLogger, $ex );
2629                                 $e = $e ?: $ex;
2630                         }
2631                 }
2632
2633                 if ( $e instanceof Exception ) {
2634                         throw $e; // re-throw any first exception
2635                 }
2636         }
2637
2638         final public function startAtomic( $fname = __METHOD__ ) {
2639                 if ( !$this->mTrxLevel ) {
2640                         $this->begin( $fname, self::TRANSACTION_INTERNAL );
2641                         // If DBO_TRX is set, a series of startAtomic/endAtomic pairs will result
2642                         // in all changes being in one transaction to keep requests transactional.
2643                         if ( !$this->getFlag( self::DBO_TRX ) ) {
2644                                 $this->mTrxAutomaticAtomic = true;
2645                         }
2646                 }
2647
2648                 $this->mTrxAtomicLevels[] = $fname;
2649         }
2650
2651         final public function endAtomic( $fname = __METHOD__ ) {
2652                 if ( !$this->mTrxLevel ) {
2653                         throw new DBUnexpectedError( $this, "No atomic transaction is open (got $fname)." );
2654                 }
2655                 if ( !$this->mTrxAtomicLevels ||
2656                         array_pop( $this->mTrxAtomicLevels ) !== $fname
2657                 ) {
2658                         throw new DBUnexpectedError( $this, "Invalid atomic section ended (got $fname)." );
2659                 }
2660
2661                 if ( !$this->mTrxAtomicLevels && $this->mTrxAutomaticAtomic ) {
2662                         $this->commit( $fname, self::FLUSHING_INTERNAL );
2663                 }
2664         }
2665
2666         final public function doAtomicSection( $fname, callable $callback ) {
2667                 $this->startAtomic( $fname );
2668                 try {
2669                         $res = call_user_func_array( $callback, [ $this, $fname ] );
2670                 } catch ( Exception $e ) {
2671                         $this->rollback( $fname, self::FLUSHING_INTERNAL );
2672                         throw $e;
2673                 }
2674                 $this->endAtomic( $fname );
2675
2676                 return $res;
2677         }
2678
2679         final public function begin( $fname = __METHOD__, $mode = self::TRANSACTION_EXPLICIT ) {
2680                 // Protect against mismatched atomic section, transaction nesting, and snapshot loss
2681                 if ( $this->mTrxLevel ) {
2682                         if ( $this->mTrxAtomicLevels ) {
2683                                 $levels = implode( ', ', $this->mTrxAtomicLevels );
2684                                 $msg = "$fname: Got explicit BEGIN while atomic section(s) $levels are open.";
2685                                 throw new DBUnexpectedError( $this, $msg );
2686                         } elseif ( !$this->mTrxAutomatic ) {
2687                                 $msg = "$fname: Explicit transaction already active (from {$this->mTrxFname}).";
2688                                 throw new DBUnexpectedError( $this, $msg );
2689                         } else {
2690                                 // @TODO: make this an exception at some point
2691                                 $msg = "$fname: Implicit transaction already active (from {$this->mTrxFname}).";
2692                                 $this->queryLogger->error( $msg );
2693                                 return; // join the main transaction set
2694                         }
2695                 } elseif ( $this->getFlag( self::DBO_TRX ) && $mode !== self::TRANSACTION_INTERNAL ) {
2696                         // @TODO: make this an exception at some point
2697                         $msg = "$fname: Implicit transaction expected (DBO_TRX set).";
2698                         $this->queryLogger->error( $msg );
2699                         return; // let any writes be in the main transaction
2700                 }
2701
2702                 // Avoid fatals if close() was called
2703                 $this->assertOpen();
2704
2705                 $this->doBegin( $fname );
2706                 $this->mTrxTimestamp = microtime( true );
2707                 $this->mTrxFname = $fname;
2708                 $this->mTrxDoneWrites = false;
2709                 $this->mTrxAutomaticAtomic = false;
2710                 $this->mTrxAtomicLevels = [];
2711                 $this->mTrxShortId = sprintf( '%06x', mt_rand( 0, 0xffffff ) );
2712                 $this->mTrxWriteDuration = 0.0;
2713                 $this->mTrxWriteQueryCount = 0;
2714                 $this->mTrxWriteAdjDuration = 0.0;
2715                 $this->mTrxWriteAdjQueryCount = 0;
2716                 $this->mTrxWriteCallers = [];
2717                 // First SELECT after BEGIN will establish the snapshot in REPEATABLE-READ.
2718                 // Get an estimate of the replica DB lag before then, treating estimate staleness
2719                 // as lag itself just to be safe
2720                 $status = $this->getApproximateLagStatus();
2721                 $this->mTrxReplicaLag = $status['lag'] + ( microtime( true ) - $status['since'] );
2722                 // T147697: make explicitTrxActive() return true until begin() finishes. This way, no
2723                 // caller will think its OK to muck around with the transaction just because startAtomic()
2724                 // has not yet completed (e.g. setting mTrxAtomicLevels).
2725                 $this->mTrxAutomatic = ( $mode === self::TRANSACTION_INTERNAL );
2726         }
2727
2728         /**
2729          * Issues the BEGIN command to the database server.
2730          *
2731          * @see Database::begin()
2732          * @param string $fname
2733          */
2734         protected function doBegin( $fname ) {
2735                 $this->query( 'BEGIN', $fname );
2736                 $this->mTrxLevel = 1;
2737         }
2738
2739         final public function commit( $fname = __METHOD__, $flush = '' ) {
2740                 if ( $this->mTrxLevel && $this->mTrxAtomicLevels ) {
2741                         // There are still atomic sections open. This cannot be ignored
2742                         $levels = implode( ', ', $this->mTrxAtomicLevels );
2743                         throw new DBUnexpectedError(
2744                                 $this,
2745                                 "$fname: Got COMMIT while atomic sections $levels are still open."
2746                         );
2747                 }
2748
2749                 if ( $flush === self::FLUSHING_INTERNAL || $flush === self::FLUSHING_ALL_PEERS ) {
2750                         if ( !$this->mTrxLevel ) {
2751                                 return; // nothing to do
2752                         } elseif ( !$this->mTrxAutomatic ) {
2753                                 throw new DBUnexpectedError(
2754                                         $this,
2755                                         "$fname: Flushing an explicit transaction, getting out of sync."
2756                                 );
2757                         }
2758                 } else {
2759                         if ( !$this->mTrxLevel ) {
2760                                 $this->queryLogger->error(
2761                                         "$fname: No transaction to commit, something got out of sync." );
2762                                 return; // nothing to do
2763                         } elseif ( $this->mTrxAutomatic ) {
2764                                 // @TODO: make this an exception at some point
2765                                 $msg = "$fname: Explicit commit of implicit transaction.";
2766                                 $this->queryLogger->error( $msg );
2767                                 return; // wait for the main transaction set commit round
2768                         }
2769                 }
2770
2771                 // Avoid fatals if close() was called
2772                 $this->assertOpen();
2773
2774                 $this->runOnTransactionPreCommitCallbacks();
2775                 $writeTime = $this->pendingWriteQueryDuration( self::ESTIMATE_DB_APPLY );
2776                 $this->doCommit( $fname );
2777                 if ( $this->mTrxDoneWrites ) {
2778                         $this->mLastWriteTime = microtime( true );
2779                         $this->trxProfiler->transactionWritingOut(
2780                                 $this->mServer, $this->mDBname, $this->mTrxShortId, $writeTime );
2781                 }
2782
2783                 $this->runOnTransactionIdleCallbacks( self::TRIGGER_COMMIT );
2784                 $this->runTransactionListenerCallbacks( self::TRIGGER_COMMIT );
2785         }
2786
2787         /**
2788          * Issues the COMMIT command to the database server.
2789          *
2790          * @see Database::commit()
2791          * @param string $fname
2792          */
2793         protected function doCommit( $fname ) {
2794                 if ( $this->mTrxLevel ) {
2795                         $this->query( 'COMMIT', $fname );
2796                         $this->mTrxLevel = 0;
2797                 }
2798         }
2799
2800         final public function rollback( $fname = __METHOD__, $flush = '' ) {
2801                 if ( $flush === self::FLUSHING_INTERNAL || $flush === self::FLUSHING_ALL_PEERS ) {
2802                         if ( !$this->mTrxLevel ) {
2803                                 return; // nothing to do
2804                         }
2805                 } else {
2806                         if ( !$this->mTrxLevel ) {
2807                                 $this->queryLogger->error(
2808                                         "$fname: No transaction to rollback, something got out of sync." );
2809                                 return; // nothing to do
2810                         } elseif ( $this->getFlag( self::DBO_TRX ) ) {
2811                                 throw new DBUnexpectedError(
2812                                         $this,
2813                                         "$fname: Expected mass rollback of all peer databases (DBO_TRX set)."
2814                                 );
2815                         }
2816                 }
2817
2818                 // Avoid fatals if close() was called
2819                 $this->assertOpen();
2820
2821                 $this->doRollback( $fname );
2822                 $this->mTrxAtomicLevels = [];
2823                 if ( $this->mTrxDoneWrites ) {
2824                         $this->trxProfiler->transactionWritingOut(
2825                                 $this->mServer, $this->mDBname, $this->mTrxShortId );
2826                 }
2827
2828                 $this->mTrxIdleCallbacks = []; // clear
2829                 $this->mTrxPreCommitCallbacks = []; // clear
2830                 $this->runOnTransactionIdleCallbacks( self::TRIGGER_ROLLBACK );
2831                 $this->runTransactionListenerCallbacks( self::TRIGGER_ROLLBACK );
2832         }
2833
2834         /**
2835          * Issues the ROLLBACK command to the database server.
2836          *
2837          * @see Database::rollback()
2838          * @param string $fname
2839          */
2840         protected function doRollback( $fname ) {
2841                 if ( $this->mTrxLevel ) {
2842                         # Disconnects cause rollback anyway, so ignore those errors
2843                         $ignoreErrors = true;
2844                         $this->query( 'ROLLBACK', $fname, $ignoreErrors );
2845                         $this->mTrxLevel = 0;
2846                 }
2847         }
2848
2849         public function flushSnapshot( $fname = __METHOD__ ) {
2850                 if ( $this->writesOrCallbacksPending() || $this->explicitTrxActive() ) {
2851                         // This only flushes transactions to clear snapshots, not to write data
2852                         $fnames = implode( ', ', $this->pendingWriteAndCallbackCallers() );
2853                         throw new DBUnexpectedError(
2854                                 $this,
2855                                 "$fname: Cannot flush snapshot because writes are pending ($fnames)."
2856                         );
2857                 }
2858
2859                 $this->commit( $fname, self::FLUSHING_INTERNAL );
2860         }
2861
2862         public function explicitTrxActive() {
2863                 return $this->mTrxLevel && ( $this->mTrxAtomicLevels || !$this->mTrxAutomatic );
2864         }
2865
2866         public function duplicateTableStructure(
2867                 $oldName, $newName, $temporary = false, $fname = __METHOD__
2868         ) {
2869                 throw new RuntimeException( __METHOD__ . ' is not implemented in descendant class' );
2870         }
2871
2872         public function listTables( $prefix = null, $fname = __METHOD__ ) {
2873                 throw new RuntimeException( __METHOD__ . ' is not implemented in descendant class' );
2874         }
2875
2876         public function listViews( $prefix = null, $fname = __METHOD__ ) {
2877                 throw new RuntimeException( __METHOD__ . ' is not implemented in descendant class' );
2878         }
2879
2880         public function timestamp( $ts = 0 ) {
2881                 $t = new ConvertibleTimestamp( $ts );
2882                 // Let errors bubble up to avoid putting garbage in the DB
2883                 return $t->getTimestamp( TS_MW );
2884         }
2885
2886         public function timestampOrNull( $ts = null ) {
2887                 if ( is_null( $ts ) ) {
2888                         return null;
2889                 } else {
2890                         return $this->timestamp( $ts );
2891                 }
2892         }
2893
2894         /**
2895          * Take the result from a query, and wrap it in a ResultWrapper if
2896          * necessary. Boolean values are passed through as is, to indicate success
2897          * of write queries or failure.
2898          *
2899          * Once upon a time, Database::query() returned a bare MySQL result
2900          * resource, and it was necessary to call this function to convert it to
2901          * a wrapper. Nowadays, raw database objects are never exposed to external
2902          * callers, so this is unnecessary in external code.
2903          *
2904          * @param bool|ResultWrapper|resource|object $result
2905          * @return bool|ResultWrapper
2906          */
2907         protected function resultObject( $result ) {
2908                 if ( !$result ) {
2909                         return false;
2910                 } elseif ( $result instanceof ResultWrapper ) {
2911                         return $result;
2912                 } elseif ( $result === true ) {
2913                         // Successful write query
2914                         return $result;
2915                 } else {
2916                         return new ResultWrapper( $this, $result );
2917                 }
2918         }
2919
2920         public function ping( &$rtt = null ) {
2921                 // Avoid hitting the server if it was hit recently
2922                 if ( $this->isOpen() && ( microtime( true ) - $this->lastPing ) < self::PING_TTL ) {
2923                         if ( !func_num_args() || $this->mRTTEstimate > 0 ) {
2924                                 $rtt = $this->mRTTEstimate;
2925                                 return true; // don't care about $rtt
2926                         }
2927                 }
2928
2929                 // This will reconnect if possible or return false if not
2930                 $this->clearFlag( self::DBO_TRX, self::REMEMBER_PRIOR );
2931                 $ok = ( $this->query( self::PING_QUERY, __METHOD__, true ) !== false );
2932                 $this->restoreFlags( self::RESTORE_PRIOR );
2933
2934                 if ( $ok ) {
2935                         $rtt = $this->mRTTEstimate;
2936                 }
2937
2938                 return $ok;
2939         }
2940
2941         /**
2942          * @return bool
2943          */
2944         protected function reconnect() {
2945                 $this->closeConnection();
2946                 $this->mOpened = false;
2947                 $this->mConn = false;
2948                 try {
2949                         $this->open( $this->mServer, $this->mUser, $this->mPassword, $this->mDBname );
2950                         $this->lastPing = microtime( true );
2951                         $ok = true;
2952                 } catch ( DBConnectionError $e ) {
2953                         $ok = false;
2954                 }
2955
2956                 return $ok;
2957         }
2958
2959         public function getSessionLagStatus() {
2960                 return $this->getTransactionLagStatus() ?: $this->getApproximateLagStatus();
2961         }
2962
2963         /**
2964          * Get the replica DB lag when the current transaction started
2965          *
2966          * This is useful when transactions might use snapshot isolation
2967          * (e.g. REPEATABLE-READ in innodb), so the "real" lag of that data
2968          * is this lag plus transaction duration. If they don't, it is still
2969          * safe to be pessimistic. This returns null if there is no transaction.
2970          *
2971          * @return array|null ('lag': seconds or false on error, 'since': UNIX timestamp of BEGIN)
2972          * @since 1.27
2973          */
2974         protected function getTransactionLagStatus() {
2975                 return $this->mTrxLevel
2976                         ? [ 'lag' => $this->mTrxReplicaLag, 'since' => $this->trxTimestamp() ]
2977                         : null;
2978         }
2979
2980         /**
2981          * Get a replica DB lag estimate for this server
2982          *
2983          * @return array ('lag': seconds or false on error, 'since': UNIX timestamp of estimate)
2984          * @since 1.27
2985          */
2986         protected function getApproximateLagStatus() {
2987                 return [
2988                         'lag'   => $this->getLBInfo( 'replica' ) ? $this->getLag() : 0,
2989                         'since' => microtime( true )
2990                 ];
2991         }
2992
2993         /**
2994          * Merge the result of getSessionLagStatus() for several DBs
2995          * using the most pessimistic values to estimate the lag of
2996          * any data derived from them in combination
2997          *
2998          * This is information is useful for caching modules
2999          *
3000          * @see WANObjectCache::set()
3001          * @see WANObjectCache::getWithSetCallback()
3002          *
3003          * @param IDatabase $db1
3004          * @param IDatabase ...
3005          * @return array Map of values:
3006          *   - lag: highest lag of any of the DBs or false on error (e.g. replication stopped)
3007          *   - since: oldest UNIX timestamp of any of the DB lag estimates
3008          *   - pending: whether any of the DBs have uncommitted changes
3009          * @since 1.27
3010          */
3011         public static function getCacheSetOptions( IDatabase $db1 ) {
3012                 $res = [ 'lag' => 0, 'since' => INF, 'pending' => false ];
3013                 foreach ( func_get_args() as $db ) {
3014                         /** @var IDatabase $db */
3015                         $status = $db->getSessionLagStatus();
3016                         if ( $status['lag'] === false ) {
3017                                 $res['lag'] = false;
3018                         } elseif ( $res['lag'] !== false ) {
3019                                 $res['lag'] = max( $res['lag'], $status['lag'] );
3020                         }
3021                         $res['since'] = min( $res['since'], $status['since'] );
3022                         $res['pending'] = $res['pending'] ?: $db->writesPending();
3023                 }
3024
3025                 return $res;
3026         }
3027
3028         public function getLag() {
3029                 return 0;
3030         }
3031
3032         public function maxListLen() {
3033                 return 0;
3034         }
3035
3036         public function encodeBlob( $b ) {
3037                 return $b;
3038         }
3039
3040         public function decodeBlob( $b ) {
3041                 if ( $b instanceof Blob ) {
3042                         $b = $b->fetch();
3043                 }
3044                 return $b;
3045         }
3046
3047         public function setSessionOptions( array $options ) {
3048         }
3049
3050         public function sourceFile(
3051                 $filename,
3052                 callable $lineCallback = null,
3053                 callable $resultCallback = null,
3054                 $fname = false,
3055                 callable $inputCallback = null
3056         ) {
3057                 MediaWiki\suppressWarnings();
3058                 $fp = fopen( $filename, 'r' );
3059                 MediaWiki\restoreWarnings();
3060
3061                 if ( false === $fp ) {
3062                         throw new RuntimeException( "Could not open \"{$filename}\".\n" );
3063                 }
3064
3065                 if ( !$fname ) {
3066                         $fname = __METHOD__ . "( $filename )";
3067                 }
3068
3069                 try {
3070                         $error = $this->sourceStream(
3071                                 $fp, $lineCallback, $resultCallback, $fname, $inputCallback );
3072                 } catch ( Exception $e ) {
3073                         fclose( $fp );
3074                         throw $e;
3075                 }
3076
3077                 fclose( $fp );
3078
3079                 return $error;
3080         }
3081
3082         public function setSchemaVars( $vars ) {
3083                 $this->mSchemaVars = $vars;
3084         }
3085
3086         public function sourceStream(
3087                 $fp,
3088                 callable $lineCallback = null,
3089                 callable $resultCallback = null,
3090                 $fname = __METHOD__,
3091                 callable $inputCallback = null
3092         ) {
3093                 $cmd = '';
3094
3095                 while ( !feof( $fp ) ) {
3096                         if ( $lineCallback ) {
3097                                 call_user_func( $lineCallback );
3098                         }
3099
3100                         $line = trim( fgets( $fp ) );
3101
3102                         if ( $line == '' ) {
3103                                 continue;
3104                         }
3105
3106                         if ( '-' == $line[0] && '-' == $line[1] ) {
3107                                 continue;
3108                         }
3109
3110                         if ( $cmd != '' ) {
3111                                 $cmd .= ' ';
3112                         }
3113
3114                         $done = $this->streamStatementEnd( $cmd, $line );
3115
3116                         $cmd .= "$line\n";
3117
3118                         if ( $done || feof( $fp ) ) {
3119                                 $cmd = $this->replaceVars( $cmd );
3120
3121                                 if ( !$inputCallback || call_user_func( $inputCallback, $cmd ) ) {
3122                                         $res = $this->query( $cmd, $fname );
3123
3124                                         if ( $resultCallback ) {
3125                                                 call_user_func( $resultCallback, $res, $this );
3126                                         }
3127
3128                                         if ( false === $res ) {
3129                                                 $err = $this->lastError();
3130
3131                                                 return "Query \"{$cmd}\" failed with error code \"$err\".\n";
3132                                         }
3133                                 }
3134                                 $cmd = '';
3135                         }
3136                 }
3137
3138                 return true;
3139         }
3140
3141         /**
3142          * Called by sourceStream() to check if we've reached a statement end
3143          *
3144          * @param string &$sql SQL assembled so far
3145          * @param string &$newLine New line about to be added to $sql
3146          * @return bool Whether $newLine contains end of the statement
3147          */
3148         public function streamStatementEnd( &$sql, &$newLine ) {
3149                 if ( $this->delimiter ) {
3150                         $prev = $newLine;
3151                         $newLine = preg_replace(
3152                                 '/' . preg_quote( $this->delimiter, '/' ) . '$/', '', $newLine );
3153                         if ( $newLine != $prev ) {
3154                                 return true;
3155                         }
3156                 }
3157
3158                 return false;
3159         }
3160
3161         /**
3162          * Database independent variable replacement. Replaces a set of variables
3163          * in an SQL statement with their contents as given by $this->getSchemaVars().
3164          *
3165          * Supports '{$var}' `{$var}` and / *$var* / (without the spaces) style variables.
3166          *
3167          * - '{$var}' should be used for text and is passed through the database's
3168          *   addQuotes method.
3169          * - `{$var}` should be used for identifiers (e.g. table and database names).
3170          *   It is passed through the database's addIdentifierQuotes method which
3171          *   can be overridden if the database uses something other than backticks.
3172          * - / *_* / or / *$wgDBprefix* / passes the name that follows through the
3173          *   database's tableName method.
3174          * - / *i* / passes the name that follows through the database's indexName method.
3175          * - In all other cases, / *$var* / is left unencoded. Except for table options,
3176          *   its use should be avoided. In 1.24 and older, string encoding was applied.
3177          *
3178          * @param string $ins SQL statement to replace variables in
3179          * @return string The new SQL statement with variables replaced
3180          */
3181         protected function replaceVars( $ins ) {
3182                 $vars = $this->getSchemaVars();
3183                 return preg_replace_callback(
3184                         '!
3185                                 /\* (\$wgDBprefix|[_i]) \*/ (\w*) | # 1-2. tableName, indexName
3186                                 \'\{\$ (\w+) }\'                  | # 3. addQuotes
3187                                 `\{\$ (\w+) }`                    | # 4. addIdentifierQuotes
3188                                 /\*\$ (\w+) \*/                     # 5. leave unencoded
3189                         !x',
3190                         function ( $m ) use ( $vars ) {
3191                                 // Note: Because of <https://bugs.php.net/bug.php?id=51881>,
3192                                 // check for both nonexistent keys *and* the empty string.
3193                                 if ( isset( $m[1] ) && $m[1] !== '' ) {
3194                                         if ( $m[1] === 'i' ) {
3195                                                 return $this->indexName( $m[2] );
3196                                         } else {
3197                                                 return $this->tableName( $m[2] );
3198                                         }
3199                                 } elseif ( isset( $m[3] ) && $m[3] !== '' && array_key_exists( $m[3], $vars ) ) {
3200                                         return $this->addQuotes( $vars[$m[3]] );
3201                                 } elseif ( isset( $m[4] ) && $m[4] !== '' && array_key_exists( $m[4], $vars ) ) {
3202                                         return $this->addIdentifierQuotes( $vars[$m[4]] );
3203                                 } elseif ( isset( $m[5] ) && $m[5] !== '' && array_key_exists( $m[5], $vars ) ) {
3204                                         return $vars[$m[5]];
3205                                 } else {
3206                                         return $m[0];
3207                                 }
3208                         },
3209                         $ins
3210                 );
3211         }
3212
3213         /**
3214          * Get schema variables. If none have been set via setSchemaVars(), then
3215          * use some defaults from the current object.
3216          *
3217          * @return array
3218          */
3219         protected function getSchemaVars() {
3220                 if ( $this->mSchemaVars ) {
3221                         return $this->mSchemaVars;
3222                 } else {
3223                         return $this->getDefaultSchemaVars();
3224                 }
3225         }
3226
3227         /**
3228          * Get schema variables to use if none have been set via setSchemaVars().
3229          *
3230          * Override this in derived classes to provide variables for tables.sql
3231          * and SQL patch files.
3232          *
3233          * @return array
3234          */
3235         protected function getDefaultSchemaVars() {
3236                 return [];
3237         }
3238
3239         public function lockIsFree( $lockName, $method ) {
3240                 return true;
3241         }
3242
3243         public function lock( $lockName, $method, $timeout = 5 ) {
3244                 $this->mNamedLocksHeld[$lockName] = 1;
3245
3246                 return true;
3247         }
3248
3249         public function unlock( $lockName, $method ) {
3250                 unset( $this->mNamedLocksHeld[$lockName] );
3251
3252                 return true;
3253         }
3254
3255         public function getScopedLockAndFlush( $lockKey, $fname, $timeout ) {
3256                 if ( $this->writesOrCallbacksPending() ) {
3257                         // This only flushes transactions to clear snapshots, not to write data
3258                         $fnames = implode( ', ', $this->pendingWriteAndCallbackCallers() );
3259                         throw new DBUnexpectedError(
3260                                 $this,
3261                                 "$fname: Cannot flush pre-lock snapshot because writes are pending ($fnames)."
3262                         );
3263                 }
3264
3265                 if ( !$this->lock( $lockKey, $fname, $timeout ) ) {
3266                         return null;
3267                 }
3268
3269                 $unlocker = new ScopedCallback( function () use ( $lockKey, $fname ) {
3270                         if ( $this->trxLevel() ) {
3271                                 // There is a good chance an exception was thrown, causing any early return
3272                                 // from the caller. Let any error handler get a chance to issue rollback().
3273                                 // If there isn't one, let the error bubble up and trigger server-side rollback.
3274                                 $this->onTransactionResolution(
3275                                         function () use ( $lockKey, $fname ) {
3276                                                 $this->unlock( $lockKey, $fname );
3277                                         },
3278                                         $fname
3279                                 );
3280                         } else {
3281                                 $this->unlock( $lockKey, $fname );
3282                         }
3283                 } );
3284
3285                 $this->commit( $fname, self::FLUSHING_INTERNAL );
3286
3287                 return $unlocker;
3288         }
3289
3290         public function namedLocksEnqueue() {
3291                 return false;
3292         }
3293
3294         /**
3295          * Lock specific tables
3296          *
3297          * @param array $read Array of tables to lock for read access
3298          * @param array $write Array of tables to lock for write access
3299          * @param string $method Name of caller
3300          * @param bool $lowPriority Whether to indicate writes to be LOW PRIORITY
3301          * @return bool
3302          */
3303         public function lockTables( $read, $write, $method, $lowPriority = true ) {
3304                 return true;
3305         }
3306
3307         /**
3308          * Unlock specific tables
3309          *
3310          * @param string $method The caller
3311          * @return bool
3312          */
3313         public function unlockTables( $method ) {
3314                 return true;
3315         }
3316
3317         /**
3318          * Delete a table
3319          * @param string $tableName
3320          * @param string $fName
3321          * @return bool|ResultWrapper
3322          * @since 1.18
3323          */
3324         public function dropTable( $tableName, $fName = __METHOD__ ) {
3325                 if ( !$this->tableExists( $tableName, $fName ) ) {
3326                         return false;
3327                 }
3328                 $sql = "DROP TABLE " . $this->tableName( $tableName ) . " CASCADE";
3329
3330                 return $this->query( $sql, $fName );
3331         }
3332
3333         public function getInfinity() {
3334                 return 'infinity';
3335         }
3336
3337         public function encodeExpiry( $expiry ) {
3338                 return ( $expiry == '' || $expiry == 'infinity' || $expiry == $this->getInfinity() )
3339                         ? $this->getInfinity()
3340                         : $this->timestamp( $expiry );
3341         }
3342
3343         public function decodeExpiry( $expiry, $format = TS_MW ) {
3344                 if ( $expiry == '' || $expiry == 'infinity' || $expiry == $this->getInfinity() ) {
3345                         return 'infinity';
3346                 }
3347
3348                 return ConvertibleTimestamp::convert( $format, $expiry );
3349         }
3350
3351         public function setBigSelects( $value = true ) {
3352                 // no-op
3353         }
3354
3355         public function isReadOnly() {
3356                 return ( $this->getReadOnlyReason() !== false );
3357         }
3358
3359         /**
3360          * @return string|bool Reason this DB is read-only or false if it is not
3361          */
3362         protected function getReadOnlyReason() {
3363                 $reason = $this->getLBInfo( 'readOnlyReason' );
3364
3365                 return is_string( $reason ) ? $reason : false;
3366         }
3367
3368         public function setTableAliases( array $aliases ) {
3369                 $this->tableAliases = $aliases;
3370         }
3371
3372         /**
3373          * @return bool Whether a DB user is required to access the DB
3374          * @since 1.28
3375          */
3376         protected function requiresDatabaseUser() {
3377                 return true;
3378         }
3379
3380         /**
3381          * Get the underlying binding handle, mConn
3382          *
3383          * Makes sure that mConn is set (disconnects and ping() failure can unset it).
3384          * This catches broken callers than catch and ignore disconnection exceptions.
3385          * Unlike checking isOpen(), this is safe to call inside of open().
3386          *
3387          * @return resource|object
3388          * @throws DBUnexpectedError
3389          * @since 1.26
3390          */
3391         protected function getBindingHandle() {
3392                 if ( !$this->mConn ) {
3393                         throw new DBUnexpectedError(
3394                                 $this,
3395                                 'DB connection was already closed or the connection dropped.'
3396                         );
3397                 }
3398
3399                 return $this->mConn;
3400         }
3401
3402         /**
3403          * @since 1.19
3404          * @return string
3405          */
3406         public function __toString() {
3407                 return (string)$this->mConn;
3408         }
3409
3410         /**
3411          * Make sure that copies do not share the same client binding handle
3412          * @throws DBConnectionError
3413          */
3414         public function __clone() {
3415                 $this->connLogger->warning(
3416                         "Cloning " . get_class( $this ) . " is not recomended; forking connection:\n" .
3417                         ( new RuntimeException() )->getTraceAsString()
3418                 );
3419
3420                 if ( $this->isOpen() ) {
3421                         // Open a new connection resource without messing with the old one
3422                         $this->mOpened = false;
3423                         $this->mConn = false;
3424                         $this->mTrxEndCallbacks = []; // don't copy
3425                         $this->handleSessionLoss(); // no trx or locks anymore
3426                         $this->open( $this->mServer, $this->mUser, $this->mPassword, $this->mDBname );
3427                         $this->lastPing = microtime( true );
3428                 }
3429         }
3430
3431         /**
3432          * Called by serialize. Throw an exception when DB connection is serialized.
3433          * This causes problems on some database engines because the connection is
3434          * not restored on unserialize.
3435          */
3436         public function __sleep() {
3437                 throw new RuntimeException( 'Database serialization may cause problems, since ' .
3438                         'the connection is not restored on wakeup.' );
3439         }
3440
3441         /**
3442          * Run a few simple sanity checks and close dangling connections
3443          */
3444         public function __destruct() {
3445                 if ( $this->mTrxLevel && $this->mTrxDoneWrites ) {
3446                         trigger_error( "Uncommitted DB writes (transaction from {$this->mTrxFname})." );
3447                 }
3448
3449                 $danglingWriters = $this->pendingWriteAndCallbackCallers();
3450                 if ( $danglingWriters ) {
3451                         $fnames = implode( ', ', $danglingWriters );
3452                         trigger_error( "DB transaction writes or callbacks still pending ($fnames)." );
3453                 }
3454
3455                 if ( $this->mConn ) {
3456                         // Avoid connection leaks for sanity. Normally, resources close at script completion.
3457                         // The connection might already be closed in zend/hhvm by now, so suppress warnings.
3458                         \MediaWiki\suppressWarnings();
3459                         $this->closeConnection();
3460                         \MediaWiki\restoreWarnings();
3461                         $this->mConn = false;
3462                         $this->mOpened = false;
3463                 }
3464         }
3465 }
3466
3467 class_alias( 'Database', 'DatabaseBase' );