includes/libs/rdbms/database/Database.php

   1 <?php
   2 /**
   3  * @defgroup Database Database
   4  *
   5  * This file deals with database interface functions
   6  * and query specifics/optimisations.
   7  *
   8  * This program is free software; you can redistribute it and/or modify
   9  * it under the terms of the GNU General Public License as published by
  10  * the Free Software Foundation; either version 2 of the License, or
  11  * (at your option) any later version.
  12  *
  13  * This program is distributed in the hope that it will be useful,
  14  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  15  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
  16  * GNU General Public License for more details.
  17  *
  18  * You should have received a copy of the GNU General Public License along
  19  * with this program; if not, write to the Free Software Foundation, Inc.,
  20  * 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
  21  * http://www.gnu.org/copyleft/gpl.html
  22  *
  23  * @file
  24  * @ingroup Database
  25  */
  26 use Psr\Log\LoggerAwareInterface;
  27 use Psr\Log\LoggerInterface;
  28 use Wikimedia\ScopedCallback;
  29 use Wikimedia\Rdbms\TransactionProfiler;
  30 use Wikimedia\Rdbms\LikeMatch;
  31 use Wikimedia\Rdbms\DatabaseDomain;
  32 use Wikimedia\Rdbms\DBMasterPos;
  33 use Wikimedia\Rdbms\Blob;
  34
  35 /**
  36  * Relational database abstraction object
  37  *
  38  * @ingroup Database
  39  * @since 1.28
  40  */
  41 abstract class Database implements IDatabase, IMaintainableDatabase, LoggerAwareInterface {
  42         /** Number of times to re-try an operation in case of deadlock */
  43         const DEADLOCK_TRIES = 4;
  44         /** Minimum time to wait before retry, in microseconds */
  45         const DEADLOCK_DELAY_MIN = 500000;
  46         /** Maximum time to wait before retry */
  47         const DEADLOCK_DELAY_MAX = 1500000;
  48
  49         /** How long before it is worth doing a dummy query to test the connection */
  50         const PING_TTL = 1.0;
  51         const PING_QUERY = 'SELECT 1 AS ping';
  52
  53         const TINY_WRITE_SEC = .010;
  54         const SLOW_WRITE_SEC = .500;
  55         const SMALL_WRITE_ROWS = 100;
  56
  57         /** @var string SQL query */
  58         protected $mLastQuery = '';
  59         /** @var float|bool UNIX timestamp of last write query */
  60         protected $mLastWriteTime = false;
  61         /** @var string|bool */
  62         protected $mPHPError = false;
  63         /** @var string */
  64         protected $mServer;
  65         /** @var string */
  66         protected $mUser;
  67         /** @var string */
  68         protected $mPassword;
  69         /** @var string */
  70         protected $mDBname;
  71         /** @var array[] $aliases Map of (table => (dbname, schema, prefix) map) */
  72         protected $tableAliases = [];
  73         /** @var bool Whether this PHP instance is for a CLI script */
  74         protected $cliMode;
  75         /** @var string Agent name for query profiling */
  76         protected $agent;
  77
  78         /** @var BagOStuff APC cache */
  79         protected $srvCache;
  80         /** @var LoggerInterface */
  81         protected $connLogger;
  82         /** @var LoggerInterface */
  83         protected $queryLogger;
  84         /** @var callback Error logging callback */
  85         protected $errorLogger;
  86
  87         /** @var resource|null Database connection */
  88         protected $mConn = null;
  89         /** @var bool */
  90         protected $mOpened = false;
  91
  92         /** @var array[] List of (callable, method name) */
  93         protected $mTrxIdleCallbacks = [];
  94         /** @var array[] List of (callable, method name) */
  95         protected $mTrxPreCommitCallbacks = [];
  96         /** @var array[] List of (callable, method name) */
  97         protected $mTrxEndCallbacks = [];
  98         /** @var callable[] Map of (name => callable) */
  99         protected $mTrxRecurringCallbacks = [];
 100         /** @var bool Whether to suppress triggering of transaction end callbacks */
 101         protected $mTrxEndCallbacksSuppressed = false;
 102
 103         /** @var string */
 104         protected $mTablePrefix = '';
 105         /** @var string */
 106         protected $mSchema = '';
 107         /** @var integer */
 108         protected $mFlags;
 109         /** @var array */
 110         protected $mLBInfo = [];
 111         /** @var bool|null */
 112         protected $mDefaultBigSelects = null;
 113         /** @var array|bool */
 114         protected $mSchemaVars = false;
 115         /** @var array */
 116         protected $mSessionVars = [];
 117         /** @var array|null */
 118         protected $preparedArgs;
 119         /** @var string|bool|null Stashed value of html_errors INI setting */
 120         protected $htmlErrors;
 121         /** @var string */
 122         protected $delimiter = ';';
 123         /** @var DatabaseDomain */
 124         protected $currentDomain;
 125
 126         /**
 127          * Either 1 if a transaction is active or 0 otherwise.
 128          * The other Trx fields may not be meaningfull if this is 0.
 129          *
 130          * @var int
 131          */
 132         protected $mTrxLevel = 0;
 133         /**
 134          * Either a short hexidecimal string if a transaction is active or ""
 135          *
 136          * @var string
 137          * @see Database::mTrxLevel
 138          */
 139         protected $mTrxShortId = '';
 140         /**
 141          * The UNIX time that the transaction started. Callers can assume that if
 142          * snapshot isolation is used, then the data is *at least* up to date to that
 143          * point (possibly more up-to-date since the first SELECT defines the snapshot).
 144          *
 145          * @var float|null
 146          * @see Database::mTrxLevel
 147          */
 148         private $mTrxTimestamp = null;
 149         /** @var float Lag estimate at the time of BEGIN */
 150         private $mTrxReplicaLag = null;
 151         /**
 152          * Remembers the function name given for starting the most recent transaction via begin().
 153          * Used to provide additional context for error reporting.
 154          *
 155          * @var string
 156          * @see Database::mTrxLevel
 157          */
 158         private $mTrxFname = null;
 159         /**
 160          * Record if possible write queries were done in the last transaction started
 161          *
 162          * @var bool
 163          * @see Database::mTrxLevel
 164          */
 165         private $mTrxDoneWrites = false;
 166         /**
 167          * Record if the current transaction was started implicitly due to DBO_TRX being set.
 168          *
 169          * @var bool
 170          * @see Database::mTrxLevel
 171          */
 172         private $mTrxAutomatic = false;
 173         /**
 174          * Array of levels of atomicity within transactions
 175          *
 176          * @var array
 177          */
 178         private $mTrxAtomicLevels = [];
 179         /**
 180          * Record if the current transaction was started implicitly by Database::startAtomic
 181          *
 182          * @var bool
 183          */
 184         private $mTrxAutomaticAtomic = false;
 185         /**
 186          * Track the write query callers of the current transaction
 187          *
 188          * @var string[]
 189          */
 190         private $mTrxWriteCallers = [];
 191         /**
 192          * @var float Seconds spent in write queries for the current transaction
 193          */
 194         private $mTrxWriteDuration = 0.0;
 195         /**
 196          * @var integer Number of write queries for the current transaction
 197          */
 198         private $mTrxWriteQueryCount = 0;
 199         /**
 200          * @var float Like mTrxWriteQueryCount but excludes lock-bound, easy to replicate, queries
 201          */
 202         private $mTrxWriteAdjDuration = 0.0;
 203         /**
 204          * @var integer Number of write queries counted in mTrxWriteAdjDuration
 205          */
 206         private $mTrxWriteAdjQueryCount = 0;
 207         /**
 208          * @var float RTT time estimate
 209          */
 210         private $mRTTEstimate = 0.0;
 211
 212         /** @var array Map of (name => 1) for locks obtained via lock() */
 213         private $mNamedLocksHeld = [];
 214         /** @var array Map of (table name => 1) for TEMPORARY tables */
 215         protected $mSessionTempTables = [];
 216
 217         /** @var IDatabase|null Lazy handle to the master DB this server replicates from */
 218         private $lazyMasterHandle;
 219
 220         /** @var float UNIX timestamp */
 221         protected $lastPing = 0.0;
 222
 223         /** @var int[] Prior mFlags values */
 224         private $priorFlags = [];
 225
 226         /** @var object|string Class name or object With profileIn/profileOut methods */
 227         protected $profiler;
 228         /** @var TransactionProfiler */
 229         protected $trxProfiler;
 230
 231         /**
 232          * Constructor and database handle and attempt to connect to the DB server
 233          *
 234          * IDatabase classes should not be constructed directly in external
 235          * code. Database::factory() should be used instead.
 236          *
 237          * @param array $params Parameters passed from Database::factory()
 238          */
 239         function __construct( array $params ) {
 240                 $server = $params['host'];
 241                 $user = $params['user'];
 242                 $password = $params['password'];
 243                 $dbName = $params['dbname'];
 244
 245                 $this->mSchema = $params['schema'];
 246                 $this->mTablePrefix = $params['tablePrefix'];
 247
 248                 $this->cliMode = $params['cliMode'];
 249                 // Agent name is added to SQL queries in a comment, so make sure it can't break out
 250                 $this->agent = str_replace( '/', '-', $params['agent'] );
 251
 252                 $this->mFlags = $params['flags'];
 253                 if ( $this->mFlags & self::DBO_DEFAULT ) {
 254                         if ( $this->cliMode ) {
 255                                 $this->mFlags &= ~self::DBO_TRX;
 256                         } else {
 257                                 $this->mFlags |= self::DBO_TRX;
 258                         }
 259                 }
 260
 261                 $this->mSessionVars = $params['variables'];
 262
 263                 $this->srvCache = isset( $params['srvCache'] )
 264                         ? $params['srvCache']
 265                         : new HashBagOStuff();
 266
 267                 $this->profiler = $params['profiler'];
 268                 $this->trxProfiler = $params['trxProfiler'];
 269                 $this->connLogger = $params['connLogger'];
 270                 $this->queryLogger = $params['queryLogger'];
 271                 $this->errorLogger = $params['errorLogger'];
 272
 273                 // Set initial dummy domain until open() sets the final DB/prefix
 274                 $this->currentDomain = DatabaseDomain::newUnspecified();
 275
 276                 if ( $user ) {
 277                         $this->open( $server, $user, $password, $dbName );
 278                 } elseif ( $this->requiresDatabaseUser() ) {
 279                         throw new InvalidArgumentException( "No database user provided." );
 280                 }
 281
 282                 // Set the domain object after open() sets the relevant fields
 283                 if ( $this->mDBname != '' ) {
 284                         // Domains with server scope but a table prefix are not used by IDatabase classes
 285                         $this->currentDomain = new DatabaseDomain( $this->mDBname, null, $this->mTablePrefix );
 286                 }
 287         }
 288
 289         /**
 290          * Construct a Database subclass instance given a database type and parameters
 291          *
 292          * This also connects to the database immediately upon object construction
 293          *
 294          * @param string $dbType A possible DB type (sqlite, mysql, postgres)
 295          * @param array $p Parameter map with keys:
 296          *   - host : The hostname of the DB server
 297          *   - user : The name of the database user the client operates under
 298          *   - password : The password for the database user
 299          *   - dbname : The name of the database to use where queries do not specify one.
 300          *      The database must exist or an error might be thrown. Setting this to the empty string
 301          *      will avoid any such errors and make the handle have no implicit database scope. This is
 302          *      useful for queries like SHOW STATUS, CREATE DATABASE, or DROP DATABASE. Note that a
 303          *      "database" in Postgres is rougly equivalent to an entire MySQL server. This the domain
 304          *      in which user names and such are defined, e.g. users are database-specific in Postgres.
 305          *   - schema : The database schema to use (if supported). A "schema" in Postgres is roughly
 306          *      equivalent to a "database" in MySQL. Note that MySQL and SQLite do not use schemas.
 307          *   - tablePrefix : Optional table prefix that is implicitly added on to all table names
 308          *      recognized in queries. This can be used in place of schemas for handle site farms.
 309          *   - flags : Optional bitfield of DBO_* constants that define connection, protocol,
 310          *      buffering, and transaction behavior. It is STRONGLY adviced to leave the DBO_DEFAULT
 311          *      flag in place UNLESS this this database simply acts as a key/value store.
 312          *   - driver: Optional name of a specific DB client driver. For MySQL, there is the old
 313          *      'mysql' driver and the newer 'mysqli' driver.
 314          *   - variables: Optional map of session variables to set after connecting. This can be
 315          *      used to adjust lock timeouts or encoding modes and the like.
 316          *   - connLogger: Optional PSR-3 logger interface instance.
 317          *   - queryLogger: Optional PSR-3 logger interface instance.
 318          *   - profiler: Optional class name or object with profileIn()/profileOut() methods.
 319          *      These will be called in query(), using a simplified version of the SQL that also
 320          *      includes the agent as a SQL comment.
 321          *   - trxProfiler: Optional TransactionProfiler instance.
 322          *   - errorLogger: Optional callback that takes an Exception and logs it.
 323          *   - cliMode: Whether to consider the execution context that of a CLI script.
 324          *   - agent: Optional name used to identify the end-user in query profiling/logging.
 325          *   - srvCache: Optional BagOStuff instance to an APC-style cache.
 326          * @return Database|null If the database driver or extension cannot be found
 327          * @throws InvalidArgumentException If the database driver or extension cannot be found
 328          * @since 1.18
 329          */
 330         final public static function factory( $dbType, $p = [] ) {
 331                 static $canonicalDBTypes = [
 332                         'mysql' => [ 'mysqli', 'mysql' ],
 333                         'postgres' => [],
 334                         'sqlite' => [],
 335                         'oracle' => [],
 336                         'mssql' => [],
 337                 ];
 338
 339                 $driver = false;
 340                 $dbType = strtolower( $dbType );
 341                 if ( isset( $canonicalDBTypes[$dbType] ) && $canonicalDBTypes[$dbType] ) {
 342                         $possibleDrivers = $canonicalDBTypes[$dbType];
 343                         if ( !empty( $p['driver'] ) ) {
 344                                 if ( in_array( $p['driver'], $possibleDrivers ) ) {
 345                                         $driver = $p['driver'];
 346                                 } else {
 347                                         throw new InvalidArgumentException( __METHOD__ .
 348                                                 " type '$dbType' does not support driver '{$p['driver']}'" );
 349                                 }
 350                         } else {
 351                                 foreach ( $possibleDrivers as $posDriver ) {
 352                                         if ( extension_loaded( $posDriver ) ) {
 353                                                 $driver = $posDriver;
 354                                                 break;
 355                                         }
 356                                 }
 357                         }
 358                 } else {
 359                         $driver = $dbType;
 360                 }
 361                 if ( $driver === false || $driver === '' ) {
 362                         throw new InvalidArgumentException( __METHOD__ .
 363                                 " no viable database extension found for type '$dbType'" );
 364                 }
 365
 366                 $class = 'Database' . ucfirst( $driver );
 367                 if ( class_exists( $class ) && is_subclass_of( $class, 'IDatabase' ) ) {
 368                         // Resolve some defaults for b/c
 369                         $p['host'] = isset( $p['host'] ) ? $p['host'] : false;
 370                         $p['user'] = isset( $p['user'] ) ? $p['user'] : false;
 371                         $p['password'] = isset( $p['password'] ) ? $p['password'] : false;
 372                         $p['dbname'] = isset( $p['dbname'] ) ? $p['dbname'] : false;
 373                         $p['flags'] = isset( $p['flags'] ) ? $p['flags'] : 0;
 374                         $p['variables'] = isset( $p['variables'] ) ? $p['variables'] : [];
 375                         $p['tablePrefix'] = isset( $p['tablePrefix'] ) ? $p['tablePrefix'] : '';
 376                         $p['schema'] = isset( $p['schema'] ) ? $p['schema'] : '';
 377                         $p['cliMode'] = isset( $p['cliMode'] ) ? $p['cliMode'] : ( PHP_SAPI === 'cli' );
 378                         $p['agent'] = isset( $p['agent'] ) ? $p['agent'] : '';
 379                         if ( !isset( $p['connLogger'] ) ) {
 380                                 $p['connLogger'] = new \Psr\Log\NullLogger();
 381                         }
 382                         if ( !isset( $p['queryLogger'] ) ) {
 383                                 $p['queryLogger'] = new \Psr\Log\NullLogger();
 384                         }
 385                         $p['profiler'] = isset( $p['profiler'] ) ? $p['profiler'] : null;
 386                         if ( !isset( $p['trxProfiler'] ) ) {
 387                                 $p['trxProfiler'] = new TransactionProfiler();
 388                         }
 389                         if ( !isset( $p['errorLogger'] ) ) {
 390                                 $p['errorLogger'] = function ( Exception $e ) {
 391                                         trigger_error( get_class( $e ) . ': ' . $e->getMessage(), E_USER_WARNING );
 392                                 };
 393                         }
 394
 395                         $conn = new $class( $p );
 396                 } else {
 397                         $conn = null;
 398                 }
 399
 400                 return $conn;
 401         }
 402
 403         public function setLogger( LoggerInterface $logger ) {
 404                 $this->queryLogger = $logger;
 405         }
 406
 407         public function getServerInfo() {
 408                 return $this->getServerVersion();
 409         }
 410
 411         public function bufferResults( $buffer = null ) {
 412                 $res = !$this->getFlag( self::DBO_NOBUFFER );
 413                 if ( $buffer !== null ) {
 414                         $buffer
 415                                 ? $this->clearFlag( self::DBO_NOBUFFER )
 416                                 : $this->setFlag( self::DBO_NOBUFFER );
 417                 }
 418
 419                 return $res;
 420         }
 421
 422         /**
 423          * Turns on (false) or off (true) the automatic generation and sending
 424          * of a "we're sorry, but there has been a database error" page on
 425          * database errors. Default is on (false). When turned off, the
 426          * code should use lastErrno() and lastError() to handle the
 427          * situation as appropriate.
 428          *
 429          * Do not use this function outside of the Database classes.
 430          *
 431          * @param null|bool $ignoreErrors
 432          * @return bool The previous value of the flag.
 433          */
 434         protected function ignoreErrors( $ignoreErrors = null ) {
 435                 $res = $this->getFlag( self::DBO_IGNORE );
 436                 if ( $ignoreErrors !== null ) {
 437                         $ignoreErrors
 438                                 ? $this->setFlag( self::DBO_IGNORE )
 439                                 : $this->clearFlag( self::DBO_IGNORE );
 440                 }
 441
 442                 return $res;
 443         }
 444
 445         public function trxLevel() {
 446                 return $this->mTrxLevel;
 447         }
 448
 449         public function trxTimestamp() {
 450                 return $this->mTrxLevel ? $this->mTrxTimestamp : null;
 451         }
 452
 453         public function tablePrefix( $prefix = null ) {
 454                 $old = $this->mTablePrefix;
 455                 if ( $prefix !== null ) {
 456                         $this->mTablePrefix = $prefix;
 457                         $this->currentDomain = ( $this->mDBname != '' )
 458                                 ? new DatabaseDomain( $this->mDBname, null, $this->mTablePrefix )
 459                                 : DatabaseDomain::newUnspecified();
 460                 }
 461
 462                 return $old;
 463         }
 464
 465         public function dbSchema( $schema = null ) {
 466                 $old = $this->mSchema;
 467                 if ( $schema !== null ) {
 468                         $this->mSchema = $schema;
 469                 }
 470
 471                 return $old;
 472         }
 473
 474         public function getLBInfo( $name = null ) {
 475                 if ( is_null( $name ) ) {
 476                         return $this->mLBInfo;
 477                 } else {
 478                         if ( array_key_exists( $name, $this->mLBInfo ) ) {
 479                                 return $this->mLBInfo[$name];
 480                         } else {
 481                                 return null;
 482                         }
 483                 }
 484         }
 485
 486         public function setLBInfo( $name, $value = null ) {
 487                 if ( is_null( $value ) ) {
 488                         $this->mLBInfo = $name;
 489                 } else {
 490                         $this->mLBInfo[$name] = $value;
 491                 }
 492         }
 493
 494         public function setLazyMasterHandle( IDatabase $conn ) {
 495                 $this->lazyMasterHandle = $conn;
 496         }
 497
 498         /**
 499          * @return IDatabase|null
 500          * @see setLazyMasterHandle()
 501          * @since 1.27
 502          */
 503         protected function getLazyMasterHandle() {
 504                 return $this->lazyMasterHandle;
 505         }
 506
 507         public function implicitGroupby() {
 508                 return true;
 509         }
 510
 511         public function implicitOrderby() {
 512                 return true;
 513         }
 514
 515         public function lastQuery() {
 516                 return $this->mLastQuery;
 517         }
 518
 519         public function doneWrites() {
 520                 return (bool)$this->mLastWriteTime;
 521         }
 522
 523         public function lastDoneWrites() {
 524                 return $this->mLastWriteTime ?: false;
 525         }
 526
 527         public function writesPending() {
 528                 return $this->mTrxLevel && $this->mTrxDoneWrites;
 529         }
 530
 531         public function writesOrCallbacksPending() {
 532                 return $this->mTrxLevel && (
 533                         $this->mTrxDoneWrites || $this->mTrxIdleCallbacks || $this->mTrxPreCommitCallbacks
 534                 );
 535         }
 536
 537         public function pendingWriteQueryDuration( $type = self::ESTIMATE_TOTAL ) {
 538                 if ( !$this->mTrxLevel ) {
 539                         return false;
 540                 } elseif ( !$this->mTrxDoneWrites ) {
 541                         return 0.0;
 542                 }
 543
 544                 switch ( $type ) {
 545                         case self::ESTIMATE_DB_APPLY:
 546                                 $this->ping( $rtt );
 547                                 $rttAdjTotal = $this->mTrxWriteAdjQueryCount * $rtt;
 548                                 $applyTime = max( $this->mTrxWriteAdjDuration - $rttAdjTotal, 0 );
 549                                 // For omitted queries, make them count as something at least
 550                                 $omitted = $this->mTrxWriteQueryCount - $this->mTrxWriteAdjQueryCount;
 551                                 $applyTime += self::TINY_WRITE_SEC * $omitted;
 552
 553                                 return $applyTime;
 554                         default: // everything
 555                                 return $this->mTrxWriteDuration;
 556                 }
 557         }
 558
 559         public function pendingWriteCallers() {
 560                 return $this->mTrxLevel ? $this->mTrxWriteCallers : [];
 561         }
 562
 563         protected function pendingWriteAndCallbackCallers() {
 564                 if ( !$this->mTrxLevel ) {
 565                         return [];
 566                 }
 567
 568                 $fnames = $this->mTrxWriteCallers;
 569                 foreach ( [
 570                         $this->mTrxIdleCallbacks,
 571                         $this->mTrxPreCommitCallbacks,
 572                         $this->mTrxEndCallbacks
 573                 ] as $callbacks ) {
 574                         foreach ( $callbacks as $callback ) {
 575                                 $fnames[] = $callback[1];
 576                         }
 577                 }
 578
 579                 return $fnames;
 580         }
 581
 582         public function isOpen() {
 583                 return $this->mOpened;
 584         }
 585
 586         public function setFlag( $flag, $remember = self::REMEMBER_NOTHING ) {
 587                 if ( $remember === self::REMEMBER_PRIOR ) {
 588                         array_push( $this->priorFlags, $this->mFlags );
 589                 }
 590                 $this->mFlags |= $flag;
 591         }
 592
 593         public function clearFlag( $flag, $remember = self::REMEMBER_NOTHING ) {
 594                 if ( $remember === self::REMEMBER_PRIOR ) {
 595                         array_push( $this->priorFlags, $this->mFlags );
 596                 }
 597                 $this->mFlags &= ~$flag;
 598         }
 599
 600         public function restoreFlags( $state = self::RESTORE_PRIOR ) {
 601                 if ( !$this->priorFlags ) {
 602                         return;
 603                 }
 604
 605                 if ( $state === self::RESTORE_INITIAL ) {
 606                         $this->mFlags = reset( $this->priorFlags );
 607                         $this->priorFlags = [];
 608                 } else {
 609                         $this->mFlags = array_pop( $this->priorFlags );
 610                 }
 611         }
 612
 613         public function getFlag( $flag ) {
 614                 return !!( $this->mFlags & $flag );
 615         }
 616
 617         /**
 618          * @param string $name Class field name
 619          * @return mixed
 620          * @deprecated Since 1.28
 621          */
 622         public function getProperty( $name ) {
 623                 return $this->$name;
 624         }
 625
 626         public function getDomainID() {
 627                 return $this->currentDomain->getId();
 628         }
 629
 630         final public function getWikiID() {
 631                 return $this->getDomainID();
 632         }
 633
 634         /**
 635          * Get information about an index into an object
 636          * @param string $table Table name
 637          * @param string $index Index name
 638          * @param string $fname Calling function name
 639          * @return mixed Database-specific index description class or false if the index does not exist
 640          */
 641         abstract function indexInfo( $table, $index, $fname = __METHOD__ );
 642
 643         /**
 644          * Wrapper for addslashes()
 645          *
 646          * @param string $s String to be slashed.
 647          * @return string Slashed string.
 648          */
 649         abstract function strencode( $s );
 650
 651         protected function installErrorHandler() {
 652                 $this->mPHPError = false;
 653                 $this->htmlErrors = ini_set( 'html_errors', '0' );
 654                 set_error_handler( [ $this, 'connectionErrorLogger' ] );
 655         }
 656
 657         /**
 658          * @return bool|string
 659          */
 660         protected function restoreErrorHandler() {
 661                 restore_error_handler();
 662                 if ( $this->htmlErrors !== false ) {
 663                         ini_set( 'html_errors', $this->htmlErrors );
 664                 }
 665
 666                 return $this->getLastPHPError();
 667         }
 668
 669         /**
 670          * @return string|bool Last PHP error for this DB (typically connection errors)
 671          */
 672         protected function getLastPHPError() {
 673                 if ( $this->mPHPError ) {
 674                         $error = preg_replace( '!\[<a.*</a>\]!', '', $this->mPHPError );
 675                         $error = preg_replace( '!^.*?:\s?(.*)$!', '$1', $error );
 676
 677                         return $error;
 678                 }
 679
 680                 return false;
 681         }
 682
 683         /**
 684          * This method should not be used outside of Database classes
 685          *
 686          * @param int $errno
 687          * @param string $errstr
 688          */
 689         public function connectionErrorLogger( $errno, $errstr ) {
 690                 $this->mPHPError = $errstr;
 691         }
 692
 693         /**
 694          * Create a log context to pass to PSR-3 logger functions.
 695          *
 696          * @param array $extras Additional data to add to context
 697          * @return array
 698          */
 699         protected function getLogContext( array $extras = [] ) {
 700                 return array_merge(
 701                         [
 702                                 'db_server' => $this->mServer,
 703                                 'db_name' => $this->mDBname,
 704                                 'db_user' => $this->mUser,
 705                         ],
 706                         $extras
 707                 );
 708         }
 709
 710         public function close() {
 711                 if ( $this->mConn ) {
 712                         if ( $this->trxLevel() ) {
 713                                 $this->commit( __METHOD__, self::FLUSHING_INTERNAL );
 714                         }
 715
 716                         $closed = $this->closeConnection();
 717                         $this->mConn = false;
 718                 } elseif ( $this->mTrxIdleCallbacks || $this->mTrxEndCallbacks ) { // sanity
 719                         throw new RuntimeException( "Transaction callbacks still pending." );
 720                 } else {
 721                         $closed = true;
 722                 }
 723                 $this->mOpened = false;
 724
 725                 return $closed;
 726         }
 727
 728         /**
 729          * Make sure isOpen() returns true as a sanity check
 730          *
 731          * @throws DBUnexpectedError
 732          */
 733         protected function assertOpen() {
 734                 if ( !$this->isOpen() ) {
 735                         throw new DBUnexpectedError( $this, "DB connection was already closed." );
 736                 }
 737         }
 738
 739         /**
 740          * Closes underlying database connection
 741          * @since 1.20
 742          * @return bool Whether connection was closed successfully
 743          */
 744         abstract protected function closeConnection();
 745
 746         public function reportConnectionError( $error = 'Unknown error' ) {
 747                 $myError = $this->lastError();
 748                 if ( $myError ) {
 749                         $error = $myError;
 750                 }
 751
 752                 # New method
 753                 throw new DBConnectionError( $this, $error );
 754         }
 755
 756         /**
 757          * The DBMS-dependent part of query()
 758          *
 759          * @param string $sql SQL query.
 760          * @return ResultWrapper|bool Result object to feed to fetchObject,
 761          *   fetchRow, ...; or false on failure
 762          */
 763         abstract protected function doQuery( $sql );
 764
 765         /**
 766          * Determine whether a query writes to the DB.
 767          * Should return true if unsure.
 768          *
 769          * @param string $sql
 770          * @return bool
 771          */
 772         protected function isWriteQuery( $sql ) {
 773                 return !preg_match(
 774                         '/^(?:SELECT|BEGIN|ROLLBACK|COMMIT|SET|SHOW|EXPLAIN|\(SELECT)\b/i', $sql );
 775         }
 776
 777         /**
 778          * @param $sql
 779          * @return string|null
 780          */
 781         protected function getQueryVerb( $sql ) {
 782                 return preg_match( '/^\s*([a-z]+)/i', $sql, $m ) ? strtoupper( $m[1] ) : null;
 783         }
 784
 785         /**
 786          * Determine whether a SQL statement is sensitive to isolation level.
 787          * A SQL statement is considered transactable if its result could vary
 788          * depending on the transaction isolation level. Operational commands
 789          * such as 'SET' and 'SHOW' are not considered to be transactable.
 790          *
 791          * @param string $sql
 792          * @return bool
 793          */
 794         protected function isTransactableQuery( $sql ) {
 795                 return !in_array(
 796                         $this->getQueryVerb( $sql ),
 797                         [ 'BEGIN', 'COMMIT', 'ROLLBACK', 'SHOW', 'SET', 'CREATE', 'ALTER' ],
 798                         true
 799                 );
 800         }
 801
 802         /**
 803          * @param string $sql A SQL query
 804          * @return bool Whether $sql is SQL for creating/dropping a new TEMPORARY table
 805          */
 806         protected function registerTempTableOperation( $sql ) {
 807                 if ( preg_match(
 808                         '/^CREATE\s+TEMPORARY\s+TABLE\s+(?:IF\s+NOT\s+EXISTS\s+)?[`"\']?(\w+)[`"\']?/i',
 809                         $sql,
 810                         $matches
 811                 ) ) {
 812                         $this->mSessionTempTables[$matches[1]] = 1;
 813
 814                         return true;
 815                 } elseif ( preg_match(
 816                         '/^DROP\s+(?:TEMPORARY\s+)?TABLE\s+(?:IF\s+EXISTS\s+)?[`"\']?(\w+)[`"\']?/i',
 817                         $sql,
 818                         $matches
 819                 ) ) {
 820                         unset( $this->mSessionTempTables[$matches[1]] );
 821
 822                         return true;
 823                 } elseif ( preg_match(
 824                         '/^(?:INSERT\s+(?:\w+\s+)?INTO|UPDATE|DELETE\s+FROM)\s+[`"\']?(\w+)[`"\']?/i',
 825                         $sql,
 826                         $matches
 827                 ) ) {
 828                         return isset( $this->mSessionTempTables[$matches[1]] );
 829                 }
 830
 831                 return false;
 832         }
 833
 834         public function query( $sql, $fname = __METHOD__, $tempIgnore = false ) {
 835                 $priorWritesPending = $this->writesOrCallbacksPending();
 836                 $this->mLastQuery = $sql;
 837
 838                 $isWrite = $this->isWriteQuery( $sql ) && !$this->registerTempTableOperation( $sql );
 839                 if ( $isWrite ) {
 840                         $reason = $this->getReadOnlyReason();
 841                         if ( $reason !== false ) {
 842                                 throw new DBReadOnlyError( $this, "Database is read-only: $reason" );
 843                         }
 844                         # Set a flag indicating that writes have been done
 845                         $this->mLastWriteTime = microtime( true );
 846                 }
 847
 848                 // Add trace comment to the begin of the sql string, right after the operator.
 849                 // Or, for one-word queries (like "BEGIN" or COMMIT") add it to the end (T44598)
 850                 $commentedSql = preg_replace( '/\s|$/', " /* $fname {$this->agent} */ ", $sql, 1 );
 851
 852                 # Start implicit transactions that wrap the request if DBO_TRX is enabled
 853                 if ( !$this->mTrxLevel && $this->getFlag( self::DBO_TRX )
 854                         && $this->isTransactableQuery( $sql )
 855                 ) {
 856                         $this->begin( __METHOD__ . " ($fname)", self::TRANSACTION_INTERNAL );
 857                         $this->mTrxAutomatic = true;
 858                 }
 859
 860                 # Keep track of whether the transaction has write queries pending
 861                 if ( $this->mTrxLevel && !$this->mTrxDoneWrites && $isWrite ) {
 862                         $this->mTrxDoneWrites = true;
 863                         $this->trxProfiler->transactionWritingIn(
 864                                 $this->mServer, $this->mDBname, $this->mTrxShortId );
 865                 }
 866
 867                 if ( $this->getFlag( self::DBO_DEBUG ) ) {
 868                         $this->queryLogger->debug( "{$this->mDBname} {$commentedSql}" );
 869                 }
 870
 871                 # Avoid fatals if close() was called
 872                 $this->assertOpen();
 873
 874                 # Send the query to the server
 875                 $ret = $this->doProfiledQuery( $sql, $commentedSql, $isWrite, $fname );
 876
 877                 # Try reconnecting if the connection was lost
 878                 if ( false === $ret && $this->wasErrorReissuable() ) {
 879                         $recoverable = $this->canRecoverFromDisconnect( $sql, $priorWritesPending );
 880                         # Stash the last error values before anything might clear them
 881                         $lastError = $this->lastError();
 882                         $lastErrno = $this->lastErrno();
 883                         # Update state tracking to reflect transaction loss due to disconnection
 884                         $this->handleSessionLoss();
 885                         if ( $this->reconnect() ) {
 886                                 $msg = __METHOD__ . ": lost connection to {$this->getServer()}; reconnected";
 887                                 $this->connLogger->warning( $msg );
 888                                 $this->queryLogger->warning(
 889                                         "$msg:\n" . ( new RuntimeException() )->getTraceAsString() );
 890
 891                                 if ( !$recoverable ) {
 892                                         # Callers may catch the exception and continue to use the DB
 893                                         $this->reportQueryError( $lastError, $lastErrno, $sql, $fname );
 894                                 } else {
 895                                         # Should be safe to silently retry the query
 896                                         $ret = $this->doProfiledQuery( $sql, $commentedSql, $isWrite, $fname );
 897                                 }
 898                         } else {
 899                                 $msg = __METHOD__ . ": lost connection to {$this->getServer()} permanently";
 900                                 $this->connLogger->error( $msg );
 901                         }
 902                 }
 903
 904                 if ( false === $ret ) {
 905                         # Deadlocks cause the entire transaction to abort, not just the statement.
 906                         # https://dev.mysql.com/doc/refman/5.7/en/innodb-error-handling.html
 907                         # https://www.postgresql.org/docs/9.1/static/explicit-locking.html
 908                         if ( $this->wasDeadlock() ) {
 909                                 if ( $this->explicitTrxActive() || $priorWritesPending ) {
 910                                         $tempIgnore = false; // not recoverable
 911                                 }
 912                                 # Update state tracking to reflect transaction loss
 913                                 $this->handleSessionLoss();
 914                         }
 915
 916                         $this->reportQueryError(
 917                                 $this->lastError(), $this->lastErrno(), $sql, $fname, $tempIgnore );
 918                 }
 919
 920                 $res = $this->resultObject( $ret );
 921
 922                 return $res;
 923         }
 924
 925         private function doProfiledQuery( $sql, $commentedSql, $isWrite, $fname ) {
 926                 $isMaster = !is_null( $this->getLBInfo( 'master' ) );
 927                 # generalizeSQL() will probably cut down the query to reasonable
 928                 # logging size most of the time. The substr is really just a sanity check.
 929                 if ( $isMaster ) {
 930                         $queryProf = 'query-m: ' . substr( self::generalizeSQL( $sql ), 0, 255 );
 931                 } else {
 932                         $queryProf = 'query: ' . substr( self::generalizeSQL( $sql ), 0, 255 );
 933                 }
 934
 935                 # Include query transaction state
 936                 $queryProf .= $this->mTrxShortId ? " [TRX#{$this->mTrxShortId}]" : "";
 937
 938                 $startTime = microtime( true );
 939                 if ( $this->profiler ) {
 940                         call_user_func( [ $this->profiler, 'profileIn' ], $queryProf );
 941                 }
 942                 $ret = $this->doQuery( $commentedSql );
 943                 if ( $this->profiler ) {
 944                         call_user_func( [ $this->profiler, 'profileOut' ], $queryProf );
 945                 }
 946                 $queryRuntime = max( microtime( true ) - $startTime, 0.0 );
 947
 948                 unset( $queryProfSection ); // profile out (if set)
 949
 950                 if ( $ret !== false ) {
 951                         $this->lastPing = $startTime;
 952                         if ( $isWrite && $this->mTrxLevel ) {
 953                                 $this->updateTrxWriteQueryTime( $sql, $queryRuntime );
 954                                 $this->mTrxWriteCallers[] = $fname;
 955                         }
 956                 }
 957
 958                 if ( $sql === self::PING_QUERY ) {
 959                         $this->mRTTEstimate = $queryRuntime;
 960                 }
 961
 962                 $this->trxProfiler->recordQueryCompletion(
 963                         $queryProf, $startTime, $isWrite, $this->affectedRows()
 964                 );
 965                 $this->queryLogger->debug( $sql, [
 966                         'method' => $fname,
 967                         'master' => $isMaster,
 968                         'runtime' => $queryRuntime,
 969                 ] );
 970
 971                 return $ret;
 972         }
 973
 974         /**
 975          * Update the estimated run-time of a query, not counting large row lock times
 976          *
 977          * LoadBalancer can be set to rollback transactions that will create huge replication
 978          * lag. It bases this estimate off of pendingWriteQueryDuration(). Certain simple
 979          * queries, like inserting a row can take a long time due to row locking. This method
 980          * uses some simple heuristics to discount those cases.
 981          *
 982          * @param string $sql A SQL write query
 983          * @param float $runtime Total runtime, including RTT
 984          */
 985         private function updateTrxWriteQueryTime( $sql, $runtime ) {
 986                 // Whether this is indicative of replica DB runtime (except for RBR or ws_repl)
 987                 $indicativeOfReplicaRuntime = true;
 988                 if ( $runtime > self::SLOW_WRITE_SEC ) {
 989                         $verb = $this->getQueryVerb( $sql );
 990                         // insert(), upsert(), replace() are fast unless bulky in size or blocked on locks
 991                         if ( $verb === 'INSERT' ) {
 992                                 $indicativeOfReplicaRuntime = $this->affectedRows() > self::SMALL_WRITE_ROWS;
 993                         } elseif ( $verb === 'REPLACE' ) {
 994                                 $indicativeOfReplicaRuntime = $this->affectedRows() > self::SMALL_WRITE_ROWS / 2;
 995                         }
 996                 }
 997
 998                 $this->mTrxWriteDuration += $runtime;
 999                 $this->mTrxWriteQueryCount += 1;
1000                 if ( $indicativeOfReplicaRuntime ) {
1001                         $this->mTrxWriteAdjDuration += $runtime;
1002                         $this->mTrxWriteAdjQueryCount += 1;
1003                 }
1004         }
1005
1006         private function canRecoverFromDisconnect( $sql, $priorWritesPending ) {
1007                 # Transaction dropped; this can mean lost writes, or REPEATABLE-READ snapshots.
1008                 # Dropped connections also mean that named locks are automatically released.
1009                 # Only allow error suppression in autocommit mode or when the lost transaction
1010                 # didn't matter anyway (aside from DBO_TRX snapshot loss).
1011                 if ( $this->mNamedLocksHeld ) {
1012                         return false; // possible critical section violation
1013                 } elseif ( $sql === 'COMMIT' ) {
1014                         return !$priorWritesPending; // nothing written anyway? (T127428)
1015                 } elseif ( $sql === 'ROLLBACK' ) {
1016                         return true; // transaction lost...which is also what was requested :)
1017                 } elseif ( $this->explicitTrxActive() ) {
1018                         return false; // don't drop atomocity
1019                 } elseif ( $priorWritesPending ) {
1020                         return false; // prior writes lost from implicit transaction
1021                 }
1022
1023                 return true;
1024         }
1025
1026         private function handleSessionLoss() {
1027                 $this->mTrxLevel = 0;
1028                 $this->mTrxIdleCallbacks = []; // T67263
1029                 $this->mTrxPreCommitCallbacks = []; // T67263
1030                 $this->mSessionTempTables = [];
1031                 $this->mNamedLocksHeld = [];
1032                 try {
1033                         // Handle callbacks in mTrxEndCallbacks
1034                         $this->runOnTransactionIdleCallbacks( self::TRIGGER_ROLLBACK );
1035                         $this->runTransactionListenerCallbacks( self::TRIGGER_ROLLBACK );
1036                         return null;
1037                 } catch ( Exception $e ) {
1038                         // Already logged; move on...
1039                         return $e;
1040                 }
1041         }
1042
1043         public function reportQueryError( $error, $errno, $sql, $fname, $tempIgnore = false ) {
1044                 if ( $this->ignoreErrors() || $tempIgnore ) {
1045                         $this->queryLogger->debug( "SQL ERROR (ignored): $error\n" );
1046                 } else {
1047                         $sql1line = mb_substr( str_replace( "\n", "\\n", $sql ), 0, 5 * 1024 );
1048                         $this->queryLogger->error(
1049                                 "{fname}\t{db_server}\t{errno}\t{error}\t{sql1line}",
1050                                 $this->getLogContext( [
1051                                         'method' => __METHOD__,
1052                                         'errno' => $errno,
1053                                         'error' => $error,
1054                                         'sql1line' => $sql1line,
1055                                         'fname' => $fname,
1056                                 ] )
1057                         );
1058                         $this->queryLogger->debug( "SQL ERROR: " . $error . "\n" );
1059                         throw new DBQueryError( $this, $error, $errno, $sql, $fname );
1060                 }
1061         }
1062
1063         public function freeResult( $res ) {
1064         }
1065
1066         public function selectField(
1067                 $table, $var, $cond = '', $fname = __METHOD__, $options = []
1068         ) {
1069                 if ( $var === '*' ) { // sanity
1070                         throw new DBUnexpectedError( $this, "Cannot use a * field: got '$var'" );
1071                 }
1072
1073                 if ( !is_array( $options ) ) {
1074                         $options = [ $options ];
1075                 }
1076
1077                 $options['LIMIT'] = 1;
1078
1079                 $res = $this->select( $table, $var, $cond, $fname, $options );
1080                 if ( $res === false || !$this->numRows( $res ) ) {
1081                         return false;
1082                 }
1083
1084                 $row = $this->fetchRow( $res );
1085
1086                 if ( $row !== false ) {
1087                         return reset( $row );
1088                 } else {
1089                         return false;
1090                 }
1091         }
1092
1093         public function selectFieldValues(
1094                 $table, $var, $cond = '', $fname = __METHOD__, $options = [], $join_conds = []
1095         ) {
1096                 if ( $var === '*' ) { // sanity
1097                         throw new DBUnexpectedError( $this, "Cannot use a * field" );
1098                 } elseif ( !is_string( $var ) ) { // sanity
1099                         throw new DBUnexpectedError( $this, "Cannot use an array of fields" );
1100                 }
1101
1102                 if ( !is_array( $options ) ) {
1103                         $options = [ $options ];
1104                 }
1105
1106                 $res = $this->select( $table, $var, $cond, $fname, $options, $join_conds );
1107                 if ( $res === false ) {
1108                         return false;
1109                 }
1110
1111                 $values = [];
1112                 foreach ( $res as $row ) {
1113                         $values[] = $row->$var;
1114                 }
1115
1116                 return $values;
1117         }
1118
1119         /**
1120          * Returns an optional USE INDEX clause to go after the table, and a
1121          * string to go at the end of the query.
1122          *
1123          * @param array $options Associative array of options to be turned into
1124          *   an SQL query, valid keys are listed in the function.
1125          * @return array
1126          * @see Database::select()
1127          */
1128         protected function makeSelectOptions( $options ) {
1129                 $preLimitTail = $postLimitTail = '';
1130                 $startOpts = '';
1131
1132                 $noKeyOptions = [];
1133
1134                 foreach ( $options as $key => $option ) {
1135                         if ( is_numeric( $key ) ) {
1136                                 $noKeyOptions[$option] = true;
1137                         }
1138                 }
1139
1140                 $preLimitTail .= $this->makeGroupByWithHaving( $options );
1141
1142                 $preLimitTail .= $this->makeOrderBy( $options );
1143
1144                 if ( isset( $noKeyOptions['FOR UPDATE'] ) ) {
1145                         $postLimitTail .= ' FOR UPDATE';
1146                 }
1147
1148                 if ( isset( $noKeyOptions['LOCK IN SHARE MODE'] ) ) {
1149                         $postLimitTail .= ' LOCK IN SHARE MODE';
1150                 }
1151
1152                 if ( isset( $noKeyOptions['DISTINCT'] ) || isset( $noKeyOptions['DISTINCTROW'] ) ) {
1153                         $startOpts .= 'DISTINCT';
1154                 }
1155
1156                 # Various MySQL extensions
1157                 if ( isset( $noKeyOptions['STRAIGHT_JOIN'] ) ) {
1158                         $startOpts .= ' /*! STRAIGHT_JOIN */';
1159                 }
1160
1161                 if ( isset( $noKeyOptions['HIGH_PRIORITY'] ) ) {
1162                         $startOpts .= ' HIGH_PRIORITY';
1163                 }
1164
1165                 if ( isset( $noKeyOptions['SQL_BIG_RESULT'] ) ) {
1166                         $startOpts .= ' SQL_BIG_RESULT';
1167                 }
1168
1169                 if ( isset( $noKeyOptions['SQL_BUFFER_RESULT'] ) ) {
1170                         $startOpts .= ' SQL_BUFFER_RESULT';
1171                 }
1172
1173                 if ( isset( $noKeyOptions['SQL_SMALL_RESULT'] ) ) {
1174                         $startOpts .= ' SQL_SMALL_RESULT';
1175                 }
1176
1177                 if ( isset( $noKeyOptions['SQL_CALC_FOUND_ROWS'] ) ) {
1178                         $startOpts .= ' SQL_CALC_FOUND_ROWS';
1179                 }
1180
1181                 if ( isset( $noKeyOptions['SQL_CACHE'] ) ) {
1182                         $startOpts .= ' SQL_CACHE';
1183                 }
1184
1185                 if ( isset( $noKeyOptions['SQL_NO_CACHE'] ) ) {
1186                         $startOpts .= ' SQL_NO_CACHE';
1187                 }
1188
1189                 if ( isset( $options['USE INDEX'] ) && is_string( $options['USE INDEX'] ) ) {
1190                         $useIndex = $this->useIndexClause( $options['USE INDEX'] );
1191                 } else {
1192                         $useIndex = '';
1193                 }
1194                 if ( isset( $options['IGNORE INDEX'] ) && is_string( $options['IGNORE INDEX'] ) ) {
1195                         $ignoreIndex = $this->ignoreIndexClause( $options['IGNORE INDEX'] );
1196                 } else {
1197                         $ignoreIndex = '';
1198                 }
1199
1200                 return [ $startOpts, $useIndex, $preLimitTail, $postLimitTail, $ignoreIndex ];
1201         }
1202
1203         /**
1204          * Returns an optional GROUP BY with an optional HAVING
1205          *
1206          * @param array $options Associative array of options
1207          * @return string
1208          * @see Database::select()
1209          * @since 1.21
1210          */
1211         protected function makeGroupByWithHaving( $options ) {
1212                 $sql = '';
1213                 if ( isset( $options['GROUP BY'] ) ) {
1214                         $gb = is_array( $options['GROUP BY'] )
1215                                 ? implode( ',', $options['GROUP BY'] )
1216                                 : $options['GROUP BY'];
1217                         $sql .= ' GROUP BY ' . $gb;
1218                 }
1219                 if ( isset( $options['HAVING'] ) ) {
1220                         $having = is_array( $options['HAVING'] )
1221                                 ? $this->makeList( $options['HAVING'], self::LIST_AND )
1222                                 : $options['HAVING'];
1223                         $sql .= ' HAVING ' . $having;
1224                 }
1225
1226                 return $sql;
1227         }
1228
1229         /**
1230          * Returns an optional ORDER BY
1231          *
1232          * @param array $options Associative array of options
1233          * @return string
1234          * @see Database::select()
1235          * @since 1.21
1236          */
1237         protected function makeOrderBy( $options ) {
1238                 if ( isset( $options['ORDER BY'] ) ) {
1239                         $ob = is_array( $options['ORDER BY'] )
1240                                 ? implode( ',', $options['ORDER BY'] )
1241                                 : $options['ORDER BY'];
1242
1243                         return ' ORDER BY ' . $ob;
1244                 }
1245
1246                 return '';
1247         }
1248
1249         public function select( $table, $vars, $conds = '', $fname = __METHOD__,
1250                 $options = [], $join_conds = [] ) {
1251                 $sql = $this->selectSQLText( $table, $vars, $conds, $fname, $options, $join_conds );
1252
1253                 return $this->query( $sql, $fname );
1254         }
1255
1256         public function selectSQLText( $table, $vars, $conds = '', $fname = __METHOD__,
1257                 $options = [], $join_conds = []
1258         ) {
1259                 if ( is_array( $vars ) ) {
1260                         $vars = implode( ',', $this->fieldNamesWithAlias( $vars ) );
1261                 }
1262
1263                 $options = (array)$options;
1264                 $useIndexes = ( isset( $options['USE INDEX'] ) && is_array( $options['USE INDEX'] ) )
1265                         ? $options['USE INDEX']
1266                         : [];
1267                 $ignoreIndexes = (
1268                         isset( $options['IGNORE INDEX'] ) &&
1269                         is_array( $options['IGNORE INDEX'] )
1270                 )
1271                         ? $options['IGNORE INDEX']
1272                         : [];
1273
1274                 if ( is_array( $table ) ) {
1275                         $from = ' FROM ' .
1276                                 $this->tableNamesWithIndexClauseOrJOIN(
1277                                         $table, $useIndexes, $ignoreIndexes, $join_conds );
1278                 } elseif ( $table != '' ) {
1279                         if ( $table[0] == ' ' ) {
1280                                 $from = ' FROM ' . $table;
1281                         } else {
1282                                 $from = ' FROM ' .
1283                                         $this->tableNamesWithIndexClauseOrJOIN(
1284                                                 [ $table ], $useIndexes, $ignoreIndexes, [] );
1285                         }
1286                 } else {
1287                         $from = '';
1288                 }
1289
1290                 list( $startOpts, $useIndex, $preLimitTail, $postLimitTail, $ignoreIndex ) =
1291                         $this->makeSelectOptions( $options );
1292
1293                 if ( !empty( $conds ) ) {
1294                         if ( is_array( $conds ) ) {
1295                                 $conds = $this->makeList( $conds, self::LIST_AND );
1296                         }
1297                         $sql = "SELECT $startOpts $vars $from $useIndex $ignoreIndex " .
1298                                 "WHERE $conds $preLimitTail";
1299                 } else {
1300                         $sql = "SELECT $startOpts $vars $from $useIndex $ignoreIndex $preLimitTail";
1301                 }
1302
1303                 if ( isset( $options['LIMIT'] ) ) {
1304                         $sql = $this->limitResult( $sql, $options['LIMIT'],
1305                                 isset( $options['OFFSET'] ) ? $options['OFFSET'] : false );
1306                 }
1307                 $sql = "$sql $postLimitTail";
1308
1309                 if ( isset( $options['EXPLAIN'] ) ) {
1310                         $sql = 'EXPLAIN ' . $sql;
1311                 }
1312
1313                 return $sql;
1314         }
1315
1316         public function selectRow( $table, $vars, $conds, $fname = __METHOD__,
1317                 $options = [], $join_conds = []
1318         ) {
1319                 $options = (array)$options;
1320                 $options['LIMIT'] = 1;
1321                 $res = $this->select( $table, $vars, $conds, $fname, $options, $join_conds );
1322
1323                 if ( $res === false ) {
1324                         return false;
1325                 }
1326
1327                 if ( !$this->numRows( $res ) ) {
1328                         return false;
1329                 }
1330
1331                 $obj = $this->fetchObject( $res );
1332
1333                 return $obj;
1334         }
1335
1336         public function estimateRowCount(
1337                 $table, $vars = '*', $conds = '', $fname = __METHOD__, $options = []
1338         ) {
1339                 $rows = 0;
1340                 $res = $this->select( $table, [ 'rowcount' => 'COUNT(*)' ], $conds, $fname, $options );
1341
1342                 if ( $res ) {
1343                         $row = $this->fetchRow( $res );
1344                         $rows = ( isset( $row['rowcount'] ) ) ? (int)$row['rowcount'] : 0;
1345                 }
1346
1347                 return $rows;
1348         }
1349
1350         public function selectRowCount(
1351                 $tables, $vars = '*', $conds = '', $fname = __METHOD__, $options = [], $join_conds = []
1352         ) {
1353                 $rows = 0;
1354                 $sql = $this->selectSQLText( $tables, '1', $conds, $fname, $options, $join_conds );
1355                 $res = $this->query( "SELECT COUNT(*) AS rowcount FROM ($sql) tmp_count", $fname );
1356
1357                 if ( $res ) {
1358                         $row = $this->fetchRow( $res );
1359                         $rows = ( isset( $row['rowcount'] ) ) ? (int)$row['rowcount'] : 0;
1360                 }
1361
1362                 return $rows;
1363         }
1364
1365         /**
1366          * Removes most variables from an SQL query and replaces them with X or N for numbers.
1367          * It's only slightly flawed. Don't use for anything important.
1368          *
1369          * @param string $sql A SQL Query
1370          *
1371          * @return string
1372          */
1373         protected static function generalizeSQL( $sql ) {
1374                 # This does the same as the regexp below would do, but in such a way
1375                 # as to avoid crashing php on some large strings.
1376                 # $sql = preg_replace( "/'([^\\\\']|\\\\.)*'|\"([^\\\\\"]|\\\\.)*\"/", "'X'", $sql );
1377
1378                 $sql = str_replace( "\\\\", '', $sql );
1379                 $sql = str_replace( "\\'", '', $sql );
1380                 $sql = str_replace( "\\\"", '', $sql );
1381                 $sql = preg_replace( "/'.*'/s", "'X'", $sql );
1382                 $sql = preg_replace( '/".*"/s', "'X'", $sql );
1383
1384                 # All newlines, tabs, etc replaced by single space
1385                 $sql = preg_replace( '/\s+/', ' ', $sql );
1386
1387                 # All numbers => N,
1388                 # except the ones surrounded by characters, e.g. l10n
1389                 $sql = preg_replace( '/-?\d+(,-?\d+)+/s', 'N,...,N', $sql );
1390                 $sql = preg_replace( '/(?<![a-zA-Z])-?\d+(?![a-zA-Z])/s', 'N', $sql );
1391
1392                 return $sql;
1393         }
1394
1395         public function fieldExists( $table, $field, $fname = __METHOD__ ) {
1396                 $info = $this->fieldInfo( $table, $field );
1397
1398                 return (bool)$info;
1399         }
1400
1401         public function indexExists( $table, $index, $fname = __METHOD__ ) {
1402                 if ( !$this->tableExists( $table ) ) {
1403                         return null;
1404                 }
1405
1406                 $info = $this->indexInfo( $table, $index, $fname );
1407                 if ( is_null( $info ) ) {
1408                         return null;
1409                 } else {
1410                         return $info !== false;
1411                 }
1412         }
1413
1414         public function tableExists( $table, $fname = __METHOD__ ) {
1415                 $tableRaw = $this->tableName( $table, 'raw' );
1416                 if ( isset( $this->mSessionTempTables[$tableRaw] ) ) {
1417                         return true; // already known to exist
1418                 }
1419
1420                 $table = $this->tableName( $table );
1421                 $ignoreErrors = true;
1422                 $res = $this->query( "SELECT 1 FROM $table LIMIT 1", $fname, $ignoreErrors );
1423
1424                 return (bool)$res;
1425         }
1426
1427         public function indexUnique( $table, $index ) {
1428                 $indexInfo = $this->indexInfo( $table, $index );
1429
1430                 if ( !$indexInfo ) {
1431                         return null;
1432                 }
1433
1434                 return !$indexInfo[0]->Non_unique;
1435         }
1436
1437         /**
1438          * Helper for Database::insert().
1439          *
1440          * @param array $options
1441          * @return string
1442          */
1443         protected function makeInsertOptions( $options ) {
1444                 return implode( ' ', $options );
1445         }
1446
1447         public function insert( $table, $a, $fname = __METHOD__, $options = [] ) {
1448                 # No rows to insert, easy just return now
1449                 if ( !count( $a ) ) {
1450                         return true;
1451                 }
1452
1453                 $table = $this->tableName( $table );
1454
1455                 if ( !is_array( $options ) ) {
1456                         $options = [ $options ];
1457                 }
1458
1459                 $fh = null;
1460                 if ( isset( $options['fileHandle'] ) ) {
1461                         $fh = $options['fileHandle'];
1462                 }
1463                 $options = $this->makeInsertOptions( $options );
1464
1465                 if ( isset( $a[0] ) && is_array( $a[0] ) ) {
1466                         $multi = true;
1467                         $keys = array_keys( $a[0] );
1468                 } else {
1469                         $multi = false;
1470                         $keys = array_keys( $a );
1471                 }
1472
1473                 $sql = 'INSERT ' . $options .
1474                         " INTO $table (" . implode( ',', $keys ) . ') VALUES ';
1475
1476                 if ( $multi ) {
1477                         $first = true;
1478                         foreach ( $a as $row ) {
1479                                 if ( $first ) {
1480                                         $first = false;
1481                                 } else {
1482                                         $sql .= ',';
1483                                 }
1484                                 $sql .= '(' . $this->makeList( $row ) . ')';
1485                         }
1486                 } else {
1487                         $sql .= '(' . $this->makeList( $a ) . ')';
1488                 }
1489
1490                 if ( $fh !== null && false === fwrite( $fh, $sql ) ) {
1491                         return false;
1492                 } elseif ( $fh !== null ) {
1493                         return true;
1494                 }
1495
1496                 return (bool)$this->query( $sql, $fname );
1497         }
1498
1499         /**
1500          * Make UPDATE options array for Database::makeUpdateOptions
1501          *
1502          * @param array $options
1503          * @return array
1504          */
1505         protected function makeUpdateOptionsArray( $options ) {
1506                 if ( !is_array( $options ) ) {
1507                         $options = [ $options ];
1508                 }
1509
1510                 $opts = [];
1511
1512                 if ( in_array( 'IGNORE', $options ) ) {
1513                         $opts[] = 'IGNORE';
1514                 }
1515
1516                 return $opts;
1517         }
1518
1519         /**
1520          * Make UPDATE options for the Database::update function
1521          *
1522          * @param array $options The options passed to Database::update
1523          * @return string
1524          */
1525         protected function makeUpdateOptions( $options ) {
1526                 $opts = $this->makeUpdateOptionsArray( $options );
1527
1528                 return implode( ' ', $opts );
1529         }
1530
1531         public function update( $table, $values, $conds, $fname = __METHOD__, $options = [] ) {
1532                 $table = $this->tableName( $table );
1533                 $opts = $this->makeUpdateOptions( $options );
1534                 $sql = "UPDATE $opts $table SET " . $this->makeList( $values, self::LIST_SET );
1535
1536                 if ( $conds !== [] && $conds !== '*' ) {
1537                         $sql .= " WHERE " . $this->makeList( $conds, self::LIST_AND );
1538                 }
1539
1540                 return $this->query( $sql, $fname );
1541         }
1542
1543         public function makeList( $a, $mode = self::LIST_COMMA ) {
1544                 if ( !is_array( $a ) ) {
1545                         throw new DBUnexpectedError( $this, __METHOD__ . ' called with incorrect parameters' );
1546                 }
1547
1548                 $first = true;
1549                 $list = '';
1550
1551                 foreach ( $a as $field => $value ) {
1552                         if ( !$first ) {
1553                                 if ( $mode == self::LIST_AND ) {
1554                                         $list .= ' AND ';
1555                                 } elseif ( $mode == self::LIST_OR ) {
1556                                         $list .= ' OR ';
1557                                 } else {
1558                                         $list .= ',';
1559                                 }
1560                         } else {
1561                                 $first = false;
1562                         }
1563
1564                         if ( ( $mode == self::LIST_AND || $mode == self::LIST_OR ) && is_numeric( $field ) ) {
1565                                 $list .= "($value)";
1566                         } elseif ( $mode == self::LIST_SET && is_numeric( $field ) ) {
1567                                 $list .= "$value";
1568                         } elseif (
1569                                 ( $mode == self::LIST_AND || $mode == self::LIST_OR ) && is_array( $value )
1570                         ) {
1571                                 // Remove null from array to be handled separately if found
1572                                 $includeNull = false;
1573                                 foreach ( array_keys( $value, null, true ) as $nullKey ) {
1574                                         $includeNull = true;
1575                                         unset( $value[$nullKey] );
1576                                 }
1577                                 if ( count( $value ) == 0 && !$includeNull ) {
1578                                         throw new InvalidArgumentException(
1579                                                 __METHOD__ . ": empty input for field $field" );
1580                                 } elseif ( count( $value ) == 0 ) {
1581                                         // only check if $field is null
1582                                         $list .= "$field IS NULL";
1583                                 } else {
1584                                         // IN clause contains at least one valid element
1585                                         if ( $includeNull ) {
1586                                                 // Group subconditions to ensure correct precedence
1587                                                 $list .= '(';
1588                                         }
1589                                         if ( count( $value ) == 1 ) {
1590                                                 // Special-case single values, as IN isn't terribly efficient
1591                                                 // Don't necessarily assume the single key is 0; we don't
1592                                                 // enforce linear numeric ordering on other arrays here.
1593                                                 $value = array_values( $value )[0];
1594                                                 $list .= $field . " = " . $this->addQuotes( $value );
1595                                         } else {
1596                                                 $list .= $field . " IN (" . $this->makeList( $value ) . ") ";
1597                                         }
1598                                         // if null present in array, append IS NULL
1599                                         if ( $includeNull ) {
1600                                                 $list .= " OR $field IS NULL)";
1601                                         }
1602                                 }
1603                         } elseif ( $value === null ) {
1604                                 if ( $mode == self::LIST_AND || $mode == self::LIST_OR ) {
1605                                         $list .= "$field IS ";
1606                                 } elseif ( $mode == self::LIST_SET ) {
1607                                         $list .= "$field = ";
1608                                 }
1609                                 $list .= 'NULL';
1610                         } else {
1611                                 if (
1612                                         $mode == self::LIST_AND || $mode == self::LIST_OR || $mode == self::LIST_SET
1613                                 ) {
1614                                         $list .= "$field = ";
1615                                 }
1616                                 $list .= $mode == self::LIST_NAMES ? $value : $this->addQuotes( $value );
1617                         }
1618                 }
1619
1620                 return $list;
1621         }
1622
1623         public function makeWhereFrom2d( $data, $baseKey, $subKey ) {
1624                 $conds = [];
1625
1626                 foreach ( $data as $base => $sub ) {
1627                         if ( count( $sub ) ) {
1628                                 $conds[] = $this->makeList(
1629                                         [ $baseKey => $base, $subKey => array_keys( $sub ) ],
1630                                         self::LIST_AND );
1631                         }
1632                 }
1633
1634                 if ( $conds ) {
1635                         return $this->makeList( $conds, self::LIST_OR );
1636                 } else {
1637                         // Nothing to search for...
1638                         return false;
1639                 }
1640         }
1641
1642         public function aggregateValue( $valuedata, $valuename = 'value' ) {
1643                 return $valuename;
1644         }
1645
1646         public function bitNot( $field ) {
1647                 return "(~$field)";
1648         }
1649
1650         public function bitAnd( $fieldLeft, $fieldRight ) {
1651                 return "($fieldLeft & $fieldRight)";
1652         }
1653
1654         public function bitOr( $fieldLeft, $fieldRight ) {
1655                 return "($fieldLeft | $fieldRight)";
1656         }
1657
1658         public function buildConcat( $stringList ) {
1659                 return 'CONCAT(' . implode( ',', $stringList ) . ')';
1660         }
1661
1662         public function buildGroupConcatField(
1663                 $delim, $table, $field, $conds = '', $join_conds = []
1664         ) {
1665                 $fld = "GROUP_CONCAT($field SEPARATOR " . $this->addQuotes( $delim ) . ')';
1666
1667                 return '(' . $this->selectSQLText( $table, $fld, $conds, null, [], $join_conds ) . ')';
1668         }
1669
1670         public function buildStringCast( $field ) {
1671                 return $field;
1672         }
1673
1674         public function selectDB( $db ) {
1675                 # Stub. Shouldn't cause serious problems if it's not overridden, but
1676                 # if your database engine supports a concept similar to MySQL's
1677                 # databases you may as well.
1678                 $this->mDBname = $db;
1679
1680                 return true;
1681         }
1682
1683         public function getDBname() {
1684                 return $this->mDBname;
1685         }
1686
1687         public function getServer() {
1688                 return $this->mServer;
1689         }
1690
1691         public function tableName( $name, $format = 'quoted' ) {
1692                 # Skip the entire process when we have a string quoted on both ends.
1693                 # Note that we check the end so that we will still quote any use of
1694                 # use of `database`.table. But won't break things if someone wants
1695                 # to query a database table with a dot in the name.
1696                 if ( $this->isQuotedIdentifier( $name ) ) {
1697                         return $name;
1698                 }
1699
1700                 # Lets test for any bits of text that should never show up in a table
1701                 # name. Basically anything like JOIN or ON which are actually part of
1702                 # SQL queries, but may end up inside of the table value to combine
1703                 # sql. Such as how the API is doing.
1704                 # Note that we use a whitespace test rather than a \b test to avoid
1705                 # any remote case where a word like on may be inside of a table name
1706                 # surrounded by symbols which may be considered word breaks.
1707                 if ( preg_match( '/(^|\s)(DISTINCT|JOIN|ON|AS)(\s|$)/i', $name ) !== 0 ) {
1708                         return $name;
1709                 }
1710
1711                 # Split database and table into proper variables.
1712                 # We reverse the explode so that database.table and table both output
1713                 # the correct table.
1714                 $dbDetails = explode( '.', $name, 3 );
1715                 if ( count( $dbDetails ) == 3 ) {
1716                         list( $database, $schema, $table ) = $dbDetails;
1717                         # We don't want any prefix added in this case
1718                         $prefix = '';
1719                 } elseif ( count( $dbDetails ) == 2 ) {
1720                         list( $database, $table ) = $dbDetails;
1721                         # We don't want any prefix added in this case
1722                         $prefix = '';
1723                         # In dbs that support it, $database may actually be the schema
1724                         # but that doesn't affect any of the functionality here
1725                         $schema = '';
1726                 } else {
1727                         list( $table ) = $dbDetails;
1728                         if ( isset( $this->tableAliases[$table] ) ) {
1729                                 $database = $this->tableAliases[$table]['dbname'];
1730                                 $schema = is_string( $this->tableAliases[$table]['schema'] )
1731                                         ? $this->tableAliases[$table]['schema']
1732                                         : $this->mSchema;
1733                                 $prefix = is_string( $this->tableAliases[$table]['prefix'] )
1734                                         ? $this->tableAliases[$table]['prefix']
1735                                         : $this->mTablePrefix;
1736                         } else {
1737                                 $database = '';
1738                                 $schema = $this->mSchema; # Default schema
1739                                 $prefix = $this->mTablePrefix; # Default prefix
1740                         }
1741                 }
1742
1743                 # Quote $table and apply the prefix if not quoted.
1744                 # $tableName might be empty if this is called from Database::replaceVars()
1745                 $tableName = "{$prefix}{$table}";
1746                 if ( $format === 'quoted'
1747                         && !$this->isQuotedIdentifier( $tableName )
1748                         && $tableName !== ''
1749                 ) {
1750                         $tableName = $this->addIdentifierQuotes( $tableName );
1751                 }
1752
1753                 # Quote $schema and $database and merge them with the table name if needed
1754                 $tableName = $this->prependDatabaseOrSchema( $schema, $tableName, $format );
1755                 $tableName = $this->prependDatabaseOrSchema( $database, $tableName, $format );
1756
1757                 return $tableName;
1758         }
1759
1760         /**
1761          * @param string|null $namespace Database or schema
1762          * @param string $relation Name of table, view, sequence, etc...
1763          * @param string $format One of (raw, quoted)
1764          * @return string Relation name with quoted and merged $namespace as needed
1765          */
1766         private function prependDatabaseOrSchema( $namespace, $relation, $format ) {
1767                 if ( strlen( $namespace ) ) {
1768                         if ( $format === 'quoted' && !$this->isQuotedIdentifier( $namespace ) ) {
1769                                 $namespace = $this->addIdentifierQuotes( $namespace );
1770                         }
1771                         $relation = $namespace . '.' . $relation;
1772                 }
1773
1774                 return $relation;
1775         }
1776
1777         public function tableNames() {
1778                 $inArray = func_get_args();
1779                 $retVal = [];
1780
1781                 foreach ( $inArray as $name ) {
1782                         $retVal[$name] = $this->tableName( $name );
1783                 }
1784
1785                 return $retVal;
1786         }
1787
1788         public function tableNamesN() {
1789                 $inArray = func_get_args();
1790                 $retVal = [];
1791
1792                 foreach ( $inArray as $name ) {
1793                         $retVal[] = $this->tableName( $name );
1794                 }
1795
1796                 return $retVal;
1797         }
1798
1799         /**
1800          * Get an aliased table name
1801          * e.g. tableName AS newTableName
1802          *
1803          * @param string $name Table name, see tableName()
1804          * @param string|bool $alias Alias (optional)
1805          * @return string SQL name for aliased table. Will not alias a table to its own name
1806          */
1807         protected function tableNameWithAlias( $name, $alias = false ) {
1808                 if ( !$alias || $alias == $name ) {
1809                         return $this->tableName( $name );
1810                 } else {
1811                         return $this->tableName( $name ) . ' ' . $this->addIdentifierQuotes( $alias );
1812                 }
1813         }
1814
1815         /**
1816          * Gets an array of aliased table names
1817          *
1818          * @param array $tables [ [alias] => table ]
1819          * @return string[] See tableNameWithAlias()
1820          */
1821         protected function tableNamesWithAlias( $tables ) {
1822                 $retval = [];
1823                 foreach ( $tables as $alias => $table ) {
1824                         if ( is_numeric( $alias ) ) {
1825                                 $alias = $table;
1826                         }
1827                         $retval[] = $this->tableNameWithAlias( $table, $alias );
1828                 }
1829
1830                 return $retval;
1831         }
1832
1833         /**
1834          * Get an aliased field name
1835          * e.g. fieldName AS newFieldName
1836          *
1837          * @param string $name Field name
1838          * @param string|bool $alias Alias (optional)
1839          * @return string SQL name for aliased field. Will not alias a field to its own name
1840          */
1841         protected function fieldNameWithAlias( $name, $alias = false ) {
1842                 if ( !$alias || (string)$alias === (string)$name ) {
1843                         return $name;
1844                 } else {
1845                         return $name . ' AS ' . $this->addIdentifierQuotes( $alias ); // PostgreSQL needs AS
1846                 }
1847         }
1848
1849         /**
1850          * Gets an array of aliased field names
1851          *
1852          * @param array $fields [ [alias] => field ]
1853          * @return string[] See fieldNameWithAlias()
1854          */
1855         protected function fieldNamesWithAlias( $fields ) {
1856                 $retval = [];
1857                 foreach ( $fields as $alias => $field ) {
1858                         if ( is_numeric( $alias ) ) {
1859                                 $alias = $field;
1860                         }
1861                         $retval[] = $this->fieldNameWithAlias( $field, $alias );
1862                 }
1863
1864                 return $retval;
1865         }
1866
1867         /**
1868          * Get the aliased table name clause for a FROM clause
1869          * which might have a JOIN and/or USE INDEX or IGNORE INDEX clause
1870          *
1871          * @param array $tables ( [alias] => table )
1872          * @param array $use_index Same as for select()
1873          * @param array $ignore_index Same as for select()
1874          * @param array $join_conds Same as for select()
1875          * @return string
1876          */
1877         protected function tableNamesWithIndexClauseOrJOIN(
1878                 $tables, $use_index = [], $ignore_index = [], $join_conds = []
1879         ) {
1880                 $ret = [];
1881                 $retJOIN = [];
1882                 $use_index = (array)$use_index;
1883                 $ignore_index = (array)$ignore_index;
1884                 $join_conds = (array)$join_conds;
1885
1886                 foreach ( $tables as $alias => $table ) {
1887                         if ( !is_string( $alias ) ) {
1888                                 // No alias? Set it equal to the table name
1889                                 $alias = $table;
1890                         }
1891                         // Is there a JOIN clause for this table?
1892                         if ( isset( $join_conds[$alias] ) ) {
1893                                 list( $joinType, $conds ) = $join_conds[$alias];
1894                                 $tableClause = $joinType;
1895                                 $tableClause .= ' ' . $this->tableNameWithAlias( $table, $alias );
1896                                 if ( isset( $use_index[$alias] ) ) { // has USE INDEX?
1897                                         $use = $this->useIndexClause( implode( ',', (array)$use_index[$alias] ) );
1898                                         if ( $use != '' ) {
1899                                                 $tableClause .= ' ' . $use;
1900                                         }
1901                                 }
1902                                 if ( isset( $ignore_index[$alias] ) ) { // has IGNORE INDEX?
1903                                         $ignore = $this->ignoreIndexClause(
1904                                                 implode( ',', (array)$ignore_index[$alias] ) );
1905                                         if ( $ignore != '' ) {
1906                                                 $tableClause .= ' ' . $ignore;
1907                                         }
1908                                 }
1909                                 $on = $this->makeList( (array)$conds, self::LIST_AND );
1910                                 if ( $on != '' ) {
1911                                         $tableClause .= ' ON (' . $on . ')';
1912                                 }
1913
1914                                 $retJOIN[] = $tableClause;
1915                         } elseif ( isset( $use_index[$alias] ) ) {
1916                                 // Is there an INDEX clause for this table?
1917                                 $tableClause = $this->tableNameWithAlias( $table, $alias );
1918                                 $tableClause .= ' ' . $this->useIndexClause(
1919                                                 implode( ',', (array)$use_index[$alias] )
1920                                         );
1921
1922                                 $ret[] = $tableClause;
1923                         } elseif ( isset( $ignore_index[$alias] ) ) {
1924                                 // Is there an INDEX clause for this table?
1925                                 $tableClause = $this->tableNameWithAlias( $table, $alias );
1926                                 $tableClause .= ' ' . $this->ignoreIndexClause(
1927                                                 implode( ',', (array)$ignore_index[$alias] )
1928                                         );
1929
1930                                 $ret[] = $tableClause;
1931                         } else {
1932                                 $tableClause = $this->tableNameWithAlias( $table, $alias );
1933
1934                                 $ret[] = $tableClause;
1935                         }
1936                 }
1937
1938                 // We can't separate explicit JOIN clauses with ',', use ' ' for those
1939                 $implicitJoins = !empty( $ret ) ? implode( ',', $ret ) : "";
1940                 $explicitJoins = !empty( $retJOIN ) ? implode( ' ', $retJOIN ) : "";
1941
1942                 // Compile our final table clause
1943                 return implode( ' ', [ $implicitJoins, $explicitJoins ] );
1944         }
1945
1946         /**
1947          * Get the name of an index in a given table.
1948          *
1949          * @param string $index
1950          * @return string
1951          */
1952         protected function indexName( $index ) {
1953                 return $index;
1954         }
1955
1956         public function addQuotes( $s ) {
1957                 if ( $s instanceof Blob ) {
1958                         $s = $s->fetch();
1959                 }
1960                 if ( $s === null ) {
1961                         return 'NULL';
1962                 } elseif ( is_bool( $s ) ) {
1963                         return (int)$s;
1964                 } else {
1965                         # This will also quote numeric values. This should be harmless,
1966                         # and protects against weird problems that occur when they really
1967                         # _are_ strings such as article titles and string->number->string
1968                         # conversion is not 1:1.
1969                         return "'" . $this->strencode( $s ) . "'";
1970                 }
1971         }
1972
1973         /**
1974          * Quotes an identifier using `backticks` or "double quotes" depending on the database type.
1975          * MySQL uses `backticks` while basically everything else uses double quotes.
1976          * Since MySQL is the odd one out here the double quotes are our generic
1977          * and we implement backticks in DatabaseMysql.
1978          *
1979          * @param string $s
1980          * @return string
1981          */
1982         public function addIdentifierQuotes( $s ) {
1983                 return '"' . str_replace( '"', '""', $s ) . '"';
1984         }
1985
1986         /**
1987          * Returns if the given identifier looks quoted or not according to
1988          * the database convention for quoting identifiers .
1989          *
1990          * @note Do not use this to determine if untrusted input is safe.
1991          *   A malicious user can trick this function.
1992          * @param string $name
1993          * @return bool
1994          */
1995         public function isQuotedIdentifier( $name ) {
1996                 return $name[0] == '"' && substr( $name, -1, 1 ) == '"';
1997         }
1998
1999         /**
2000          * @param string $s
2001          * @return string
2002          */
2003         protected function escapeLikeInternal( $s ) {
2004                 return addcslashes( $s, '\%_' );
2005         }
2006
2007         public function buildLike() {
2008                 $params = func_get_args();
2009
2010                 if ( count( $params ) > 0 && is_array( $params[0] ) ) {
2011                         $params = $params[0];
2012                 }
2013
2014                 $s = '';
2015
2016                 foreach ( $params as $value ) {
2017                         if ( $value instanceof LikeMatch ) {
2018                                 $s .= $value->toString();
2019                         } else {
2020                                 $s .= $this->escapeLikeInternal( $value );
2021                         }
2022                 }
2023
2024                 return " LIKE {$this->addQuotes( $s )} ";
2025         }
2026
2027         public function anyChar() {
2028                 return new LikeMatch( '_' );
2029         }
2030
2031         public function anyString() {
2032                 return new LikeMatch( '%' );
2033         }
2034
2035         public function nextSequenceValue( $seqName ) {
2036                 return null;
2037         }
2038
2039         /**
2040          * USE INDEX clause. Unlikely to be useful for anything but MySQL. This
2041          * is only needed because a) MySQL must be as efficient as possible due to
2042          * its use on Wikipedia, and b) MySQL 4.0 is kind of dumb sometimes about
2043          * which index to pick. Anyway, other databases might have different
2044          * indexes on a given table. So don't bother overriding this unless you're
2045          * MySQL.
2046          * @param string $index
2047          * @return string
2048          */
2049         public function useIndexClause( $index ) {
2050                 return '';
2051         }
2052
2053         /**
2054          * IGNORE INDEX clause. Unlikely to be useful for anything but MySQL. This
2055          * is only needed because a) MySQL must be as efficient as possible due to
2056          * its use on Wikipedia, and b) MySQL 4.0 is kind of dumb sometimes about
2057          * which index to pick. Anyway, other databases might have different
2058          * indexes on a given table. So don't bother overriding this unless you're
2059          * MySQL.
2060          * @param string $index
2061          * @return string
2062          */
2063         public function ignoreIndexClause( $index ) {
2064                 return '';
2065         }
2066
2067         public function replace( $table, $uniqueIndexes, $rows, $fname = __METHOD__ ) {
2068                 $quotedTable = $this->tableName( $table );
2069
2070                 if ( count( $rows ) == 0 ) {
2071                         return;
2072                 }
2073
2074                 # Single row case
2075                 if ( !is_array( reset( $rows ) ) ) {
2076                         $rows = [ $rows ];
2077                 }
2078
2079                 // @FXIME: this is not atomic, but a trx would break affectedRows()
2080                 foreach ( $rows as $row ) {
2081                         # Delete rows which collide
2082                         if ( $uniqueIndexes ) {
2083                                 $sql = "DELETE FROM $quotedTable WHERE ";
2084                                 $first = true;
2085                                 foreach ( $uniqueIndexes as $index ) {
2086                                         if ( $first ) {
2087                                                 $first = false;
2088                                                 $sql .= '( ';
2089                                         } else {
2090                                                 $sql .= ' ) OR ( ';
2091                                         }
2092                                         if ( is_array( $index ) ) {
2093                                                 $first2 = true;
2094                                                 foreach ( $index as $col ) {
2095                                                         if ( $first2 ) {
2096                                                                 $first2 = false;
2097                                                         } else {
2098                                                                 $sql .= ' AND ';
2099                                                         }
2100                                                         $sql .= $col . '=' . $this->addQuotes( $row[$col] );
2101                                                 }
2102                                         } else {
2103                                                 $sql .= $index . '=' . $this->addQuotes( $row[$index] );
2104                                         }
2105                                 }
2106                                 $sql .= ' )';
2107                                 $this->query( $sql, $fname );
2108                         }
2109
2110                         # Now insert the row
2111                         $this->insert( $table, $row, $fname );
2112                 }
2113         }
2114
2115         /**
2116          * REPLACE query wrapper for MySQL and SQLite, which have a native REPLACE
2117          * statement.
2118          *
2119          * @param string $table Table name
2120          * @param array|string $rows Row(s) to insert
2121          * @param string $fname Caller function name
2122          *
2123          * @return ResultWrapper
2124          */
2125         protected function nativeReplace( $table, $rows, $fname ) {
2126                 $table = $this->tableName( $table );
2127
2128                 # Single row case
2129                 if ( !is_array( reset( $rows ) ) ) {
2130                         $rows = [ $rows ];
2131                 }
2132
2133                 $sql = "REPLACE INTO $table (" . implode( ',', array_keys( $rows[0] ) ) . ') VALUES ';
2134                 $first = true;
2135
2136                 foreach ( $rows as $row ) {
2137                         if ( $first ) {
2138                                 $first = false;
2139                         } else {
2140                                 $sql .= ',';
2141                         }
2142
2143                         $sql .= '(' . $this->makeList( $row ) . ')';
2144                 }
2145
2146                 return $this->query( $sql, $fname );
2147         }
2148
2149         public function upsert( $table, array $rows, array $uniqueIndexes, array $set,
2150                 $fname = __METHOD__
2151         ) {
2152                 if ( !count( $rows ) ) {
2153                         return true; // nothing to do
2154                 }
2155
2156                 if ( !is_array( reset( $rows ) ) ) {
2157                         $rows = [ $rows ];
2158                 }
2159
2160                 if ( count( $uniqueIndexes ) ) {
2161                         $clauses = []; // list WHERE clauses that each identify a single row
2162                         foreach ( $rows as $row ) {
2163                                 foreach ( $uniqueIndexes as $index ) {
2164                                         $index = is_array( $index ) ? $index : [ $index ]; // columns
2165                                         $rowKey = []; // unique key to this row
2166                                         foreach ( $index as $column ) {
2167                                                 $rowKey[$column] = $row[$column];
2168                                         }
2169                                         $clauses[] = $this->makeList( $rowKey, self::LIST_AND );
2170                                 }
2171                         }
2172                         $where = [ $this->makeList( $clauses, self::LIST_OR ) ];
2173                 } else {
2174                         $where = false;
2175                 }
2176
2177                 $useTrx = !$this->mTrxLevel;
2178                 if ( $useTrx ) {
2179                         $this->begin( $fname, self::TRANSACTION_INTERNAL );
2180                 }
2181                 try {
2182                         # Update any existing conflicting row(s)
2183                         if ( $where !== false ) {
2184                                 $ok = $this->update( $table, $set, $where, $fname );
2185                         } else {
2186                                 $ok = true;
2187                         }
2188                         # Now insert any non-conflicting row(s)
2189                         $ok = $this->insert( $table, $rows, $fname, [ 'IGNORE' ] ) && $ok;
2190                 } catch ( Exception $e ) {
2191                         if ( $useTrx ) {
2192                                 $this->rollback( $fname, self::FLUSHING_INTERNAL );
2193                         }
2194                         throw $e;
2195                 }
2196                 if ( $useTrx ) {
2197                         $this->commit( $fname, self::FLUSHING_INTERNAL );
2198                 }
2199
2200                 return $ok;
2201         }
2202
2203         public function deleteJoin( $delTable, $joinTable, $delVar, $joinVar, $conds,
2204                 $fname = __METHOD__
2205         ) {
2206                 if ( !$conds ) {
2207                         throw new DBUnexpectedError( $this, __METHOD__ . ' called with empty $conds' );
2208                 }
2209
2210                 $delTable = $this->tableName( $delTable );
2211                 $joinTable = $this->tableName( $joinTable );
2212                 $sql = "DELETE FROM $delTable WHERE $delVar IN (SELECT $joinVar FROM $joinTable ";
2213                 if ( $conds != '*' ) {
2214                         $sql .= 'WHERE ' . $this->makeList( $conds, self::LIST_AND );
2215                 }
2216                 $sql .= ')';
2217
2218                 $this->query( $sql, $fname );
2219         }
2220
2221         public function textFieldSize( $table, $field ) {
2222                 $table = $this->tableName( $table );
2223                 $sql = "SHOW COLUMNS FROM $table LIKE \"$field\";";
2224                 $res = $this->query( $sql, __METHOD__ );
2225                 $row = $this->fetchObject( $res );
2226
2227                 $m = [];
2228
2229                 if ( preg_match( '/\((.*)\)/', $row->Type, $m ) ) {
2230                         $size = $m[1];
2231                 } else {
2232                         $size = -1;
2233                 }
2234
2235                 return $size;
2236         }
2237
2238         public function delete( $table, $conds, $fname = __METHOD__ ) {
2239                 if ( !$conds ) {
2240                         throw new DBUnexpectedError( $this, __METHOD__ . ' called with no conditions' );
2241                 }
2242
2243                 $table = $this->tableName( $table );
2244                 $sql = "DELETE FROM $table";
2245
2246                 if ( $conds != '*' ) {
2247                         if ( is_array( $conds ) ) {
2248                                 $conds = $this->makeList( $conds, self::LIST_AND );
2249                         }
2250                         $sql .= ' WHERE ' . $conds;
2251                 }
2252
2253                 return $this->query( $sql, $fname );
2254         }
2255
2256         public function insertSelect(
2257                 $destTable, $srcTable, $varMap, $conds,
2258                 $fname = __METHOD__, $insertOptions = [], $selectOptions = []
2259         ) {
2260                 if ( $this->cliMode ) {
2261                         // For massive migrations with downtime, we don't want to select everything
2262                         // into memory and OOM, so do all this native on the server side if possible.
2263                         return $this->nativeInsertSelect(
2264                                 $destTable,
2265                                 $srcTable,
2266                                 $varMap,
2267                                 $conds,
2268                                 $fname,
2269                                 $insertOptions,
2270                                 $selectOptions
2271                         );
2272                 }
2273
2274                 // For web requests, do a locking SELECT and then INSERT. This puts the SELECT burden
2275                 // on only the master (without needing row-based-replication). It also makes it easy to
2276                 // know how big the INSERT is going to be.
2277                 $fields = [];
2278                 foreach ( $varMap as $dstColumn => $sourceColumnOrSql ) {
2279                         $fields[] = $this->fieldNameWithAlias( $sourceColumnOrSql, $dstColumn );
2280                 }
2281                 $selectOptions[] = 'FOR UPDATE';
2282                 $res = $this->select( $srcTable, implode( ',', $fields ), $conds, $fname, $selectOptions );
2283                 if ( !$res ) {
2284                         return false;
2285                 }
2286
2287                 $rows = [];
2288                 foreach ( $res as $row ) {
2289                         $rows[] = (array)$row;
2290                 }
2291
2292                 return $this->insert( $destTable, $rows, $fname, $insertOptions );
2293         }
2294
2295         protected function nativeInsertSelect( $destTable, $srcTable, $varMap, $conds,
2296                 $fname = __METHOD__,
2297                 $insertOptions = [], $selectOptions = []
2298         ) {
2299                 $destTable = $this->tableName( $destTable );
2300
2301                 if ( !is_array( $insertOptions ) ) {
2302                         $insertOptions = [ $insertOptions ];
2303                 }
2304
2305                 $insertOptions = $this->makeInsertOptions( $insertOptions );
2306
2307                 if ( !is_array( $selectOptions ) ) {
2308                         $selectOptions = [ $selectOptions ];
2309                 }
2310
2311                 list( $startOpts, $useIndex, $tailOpts, $ignoreIndex ) = $this->makeSelectOptions(
2312                         $selectOptions );
2313
2314                 if ( is_array( $srcTable ) ) {
2315                         $srcTable = implode( ',', array_map( [ $this, 'tableName' ], $srcTable ) );
2316                 } else {
2317                         $srcTable = $this->tableName( $srcTable );
2318                 }
2319
2320                 $sql = "INSERT $insertOptions" .
2321                         " INTO $destTable (" . implode( ',', array_keys( $varMap ) ) . ')' .
2322                         " SELECT $startOpts " . implode( ',', $varMap ) .
2323                         " FROM $srcTable $useIndex $ignoreIndex ";
2324
2325                 if ( $conds != '*' ) {
2326                         if ( is_array( $conds ) ) {
2327                                 $conds = $this->makeList( $conds, self::LIST_AND );
2328                         }
2329                         $sql .= " WHERE $conds";
2330                 }
2331
2332                 $sql .= " $tailOpts";
2333
2334                 return $this->query( $sql, $fname );
2335         }
2336
2337         /**
2338          * Construct a LIMIT query with optional offset. This is used for query
2339          * pages. The SQL should be adjusted so that only the first $limit rows
2340          * are returned. If $offset is provided as well, then the first $offset
2341          * rows should be discarded, and the next $limit rows should be returned.
2342          * If the result of the query is not ordered, then the rows to be returned
2343          * are theoretically arbitrary.
2344          *
2345          * $sql is expected to be a SELECT, if that makes a difference.
2346          *
2347          * The version provided by default works in MySQL and SQLite. It will very
2348          * likely need to be overridden for most other DBMSes.
2349          *
2350          * @param string $sql SQL query we will append the limit too
2351          * @param int $limit The SQL limit
2352          * @param int|bool $offset The SQL offset (default false)
2353          * @throws DBUnexpectedError
2354          * @return string
2355          */
2356         public function limitResult( $sql, $limit, $offset = false ) {
2357                 if ( !is_numeric( $limit ) ) {
2358                         throw new DBUnexpectedError( $this,
2359                                 "Invalid non-numeric limit passed to limitResult()\n" );
2360                 }
2361
2362                 return "$sql LIMIT "
2363                 . ( ( is_numeric( $offset ) && $offset != 0 ) ? "{$offset}," : "" )
2364                 . "{$limit} ";
2365         }
2366
2367         public function unionSupportsOrderAndLimit() {
2368                 return true; // True for almost every DB supported
2369         }
2370
2371         public function unionQueries( $sqls, $all ) {
2372                 $glue = $all ? ') UNION ALL (' : ') UNION (';
2373
2374                 return '(' . implode( $glue, $sqls ) . ')';
2375         }
2376
2377         public function conditional( $cond, $trueVal, $falseVal ) {
2378                 if ( is_array( $cond ) ) {
2379                         $cond = $this->makeList( $cond, self::LIST_AND );
2380                 }
2381
2382                 return " (CASE WHEN $cond THEN $trueVal ELSE $falseVal END) ";
2383         }
2384
2385         public function strreplace( $orig, $old, $new ) {
2386                 return "REPLACE({$orig}, {$old}, {$new})";
2387         }
2388
2389         public function getServerUptime() {
2390                 return 0;
2391         }
2392
2393         public function wasDeadlock() {
2394                 return false;
2395         }
2396
2397         public function wasLockTimeout() {
2398                 return false;
2399         }
2400
2401         public function wasErrorReissuable() {
2402                 return false;
2403         }
2404
2405         public function wasReadOnlyError() {
2406                 return false;
2407         }
2408
2409         /**
2410          * Do not use this method outside of Database/DBError classes
2411          *
2412          * @param integer|string $errno
2413          * @return bool Whether the given query error was a connection drop
2414          */
2415         public function wasConnectionError( $errno ) {
2416                 return false;
2417         }
2418
2419         public function deadlockLoop() {
2420                 $args = func_get_args();
2421                 $function = array_shift( $args );
2422                 $tries = self::DEADLOCK_TRIES;
2423
2424                 $this->begin( __METHOD__ );
2425
2426                 $retVal = null;
2427                 /** @var Exception $e */
2428                 $e = null;
2429                 do {
2430                         try {
2431                                 $retVal = call_user_func_array( $function, $args );
2432                                 break;
2433                         } catch ( DBQueryError $e ) {
2434                                 if ( $this->wasDeadlock() ) {
2435                                         // Retry after a randomized delay
2436                                         usleep( mt_rand( self::DEADLOCK_DELAY_MIN, self::DEADLOCK_DELAY_MAX ) );
2437                                 } else {
2438                                         // Throw the error back up
2439                                         throw $e;
2440                                 }
2441                         }
2442                 } while ( --$tries > 0 );
2443
2444                 if ( $tries <= 0 ) {
2445                         // Too many deadlocks; give up
2446                         $this->rollback( __METHOD__ );
2447                         throw $e;
2448                 } else {
2449                         $this->commit( __METHOD__ );
2450
2451                         return $retVal;
2452                 }
2453         }
2454
2455         public function masterPosWait( DBMasterPos $pos, $timeout ) {
2456                 # Real waits are implemented in the subclass.
2457                 return 0;
2458         }
2459
2460         public function getReplicaPos() {
2461                 # Stub
2462                 return false;
2463         }
2464
2465         public function getMasterPos() {
2466                 # Stub
2467                 return false;
2468         }
2469
2470         public function serverIsReadOnly() {
2471                 return false;
2472         }
2473
2474         final public function onTransactionResolution( callable $callback, $fname = __METHOD__ ) {
2475                 if ( !$this->mTrxLevel ) {
2476                         throw new DBUnexpectedError( $this, "No transaction is active." );
2477                 }
2478                 $this->mTrxEndCallbacks[] = [ $callback, $fname ];
2479         }
2480
2481         final public function onTransactionIdle( callable $callback, $fname = __METHOD__ ) {
2482                 $this->mTrxIdleCallbacks[] = [ $callback, $fname ];
2483                 if ( !$this->mTrxLevel ) {
2484                         $this->runOnTransactionIdleCallbacks( self::TRIGGER_IDLE );
2485                 }
2486         }
2487
2488         final public function onTransactionPreCommitOrIdle( callable $callback, $fname = __METHOD__ ) {
2489                 if ( $this->mTrxLevel ) {
2490                         $this->mTrxPreCommitCallbacks[] = [ $callback, $fname ];
2491                 } else {
2492                         // If no transaction is active, then make one for this callback
2493                         $this->startAtomic( __METHOD__ );
2494                         try {
2495                                 call_user_func( $callback );
2496                                 $this->endAtomic( __METHOD__ );
2497                         } catch ( Exception $e ) {
2498                                 $this->rollback( __METHOD__, self::FLUSHING_INTERNAL );
2499                                 throw $e;
2500                         }
2501                 }
2502         }
2503
2504         final public function setTransactionListener( $name, callable $callback = null ) {
2505                 if ( $callback ) {
2506                         $this->mTrxRecurringCallbacks[$name] = $callback;
2507                 } else {
2508                         unset( $this->mTrxRecurringCallbacks[$name] );
2509                 }
2510         }
2511
2512         /**
2513          * Whether to disable running of post-COMMIT/ROLLBACK callbacks
2514          *
2515          * This method should not be used outside of Database/LoadBalancer
2516          *
2517          * @param bool $suppress
2518          * @since 1.28
2519          */
2520         final public function setTrxEndCallbackSuppression( $suppress ) {
2521                 $this->mTrxEndCallbacksSuppressed = $suppress;
2522         }
2523
2524         /**
2525          * Actually run and consume any "on transaction idle/resolution" callbacks.
2526          *
2527          * This method should not be used outside of Database/LoadBalancer
2528          *
2529          * @param integer $trigger IDatabase::TRIGGER_* constant
2530          * @since 1.20
2531          * @throws Exception
2532          */
2533         public function runOnTransactionIdleCallbacks( $trigger ) {
2534                 if ( $this->mTrxEndCallbacksSuppressed ) {
2535                         return;
2536                 }
2537
2538                 $autoTrx = $this->getFlag( self::DBO_TRX ); // automatic begin() enabled?
2539                 /** @var Exception $e */
2540                 $e = null; // first exception
2541                 do { // callbacks may add callbacks :)
2542                         $callbacks = array_merge(
2543                                 $this->mTrxIdleCallbacks,
2544                                 $this->mTrxEndCallbacks // include "transaction resolution" callbacks
2545                         );
2546                         $this->mTrxIdleCallbacks = []; // consumed (and recursion guard)
2547                         $this->mTrxEndCallbacks = []; // consumed (recursion guard)
2548                         foreach ( $callbacks as $callback ) {
2549                                 try {
2550                                         list( $phpCallback ) = $callback;
2551                                         $this->clearFlag( self::DBO_TRX ); // make each query its own transaction
2552                                         call_user_func_array( $phpCallback, [ $trigger ] );
2553                                         if ( $autoTrx ) {
2554                                                 $this->setFlag( self::DBO_TRX ); // restore automatic begin()
2555                                         } else {
2556                                                 $this->clearFlag( self::DBO_TRX ); // restore auto-commit
2557                                         }
2558                                 } catch ( Exception $ex ) {
2559                                         call_user_func( $this->errorLogger, $ex );
2560                                         $e = $e ?: $ex;
2561                                         // Some callbacks may use startAtomic/endAtomic, so make sure
2562                                         // their transactions are ended so other callbacks don't fail
2563                                         if ( $this->trxLevel() ) {
2564                                                 $this->rollback( __METHOD__, self::FLUSHING_INTERNAL );
2565                                         }
2566                                 }
2567                         }
2568                 } while ( count( $this->mTrxIdleCallbacks ) );
2569
2570                 if ( $e instanceof Exception ) {
2571                         throw $e; // re-throw any first exception
2572                 }
2573         }
2574
2575         /**
2576          * Actually run and consume any "on transaction pre-commit" callbacks.
2577          *
2578          * This method should not be used outside of Database/LoadBalancer
2579          *
2580          * @since 1.22
2581          * @throws Exception
2582          */
2583         public function runOnTransactionPreCommitCallbacks() {
2584                 $e = null; // first exception
2585                 do { // callbacks may add callbacks :)
2586                         $callbacks = $this->mTrxPreCommitCallbacks;
2587                         $this->mTrxPreCommitCallbacks = []; // consumed (and recursion guard)
2588                         foreach ( $callbacks as $callback ) {
2589                                 try {
2590                                         list( $phpCallback ) = $callback;
2591                                         call_user_func( $phpCallback );
2592                                 } catch ( Exception $ex ) {
2593                                         call_user_func( $this->errorLogger, $ex );
2594                                         $e = $e ?: $ex;
2595                                 }
2596                         }
2597                 } while ( count( $this->mTrxPreCommitCallbacks ) );
2598
2599                 if ( $e instanceof Exception ) {
2600                         throw $e; // re-throw any first exception
2601                 }
2602         }
2603
2604         /**
2605          * Actually run any "transaction listener" callbacks.
2606          *
2607          * This method should not be used outside of Database/LoadBalancer
2608          *
2609          * @param integer $trigger IDatabase::TRIGGER_* constant
2610          * @throws Exception
2611          * @since 1.20
2612          */
2613         public function runTransactionListenerCallbacks( $trigger ) {
2614                 if ( $this->mTrxEndCallbacksSuppressed ) {
2615                         return;
2616                 }
2617
2618                 /** @var Exception $e */
2619                 $e = null; // first exception
2620
2621                 foreach ( $this->mTrxRecurringCallbacks as $phpCallback ) {
2622                         try {
2623                                 $phpCallback( $trigger, $this );
2624                         } catch ( Exception $ex ) {
2625                                 call_user_func( $this->errorLogger, $ex );
2626                                 $e = $e ?: $ex;
2627                         }
2628                 }
2629
2630                 if ( $e instanceof Exception ) {
2631                         throw $e; // re-throw any first exception
2632                 }
2633         }
2634
2635         final public function startAtomic( $fname = __METHOD__ ) {
2636                 if ( !$this->mTrxLevel ) {
2637                         $this->begin( $fname, self::TRANSACTION_INTERNAL );
2638                         // If DBO_TRX is set, a series of startAtomic/endAtomic pairs will result
2639                         // in all changes being in one transaction to keep requests transactional.
2640                         if ( !$this->getFlag( self::DBO_TRX ) ) {
2641                                 $this->mTrxAutomaticAtomic = true;
2642                         }
2643                 }
2644
2645                 $this->mTrxAtomicLevels[] = $fname;
2646         }
2647
2648         final public function endAtomic( $fname = __METHOD__ ) {
2649                 if ( !$this->mTrxLevel ) {
2650                         throw new DBUnexpectedError( $this, "No atomic transaction is open (got $fname)." );
2651                 }
2652                 if ( !$this->mTrxAtomicLevels ||
2653                         array_pop( $this->mTrxAtomicLevels ) !== $fname
2654                 ) {
2655                         throw new DBUnexpectedError( $this, "Invalid atomic section ended (got $fname)." );
2656                 }
2657
2658                 if ( !$this->mTrxAtomicLevels && $this->mTrxAutomaticAtomic ) {
2659                         $this->commit( $fname, self::FLUSHING_INTERNAL );
2660                 }
2661         }
2662
2663         final public function doAtomicSection( $fname, callable $callback ) {
2664                 $this->startAtomic( $fname );
2665                 try {
2666                         $res = call_user_func_array( $callback, [ $this, $fname ] );
2667                 } catch ( Exception $e ) {
2668                         $this->rollback( $fname, self::FLUSHING_INTERNAL );
2669                         throw $e;
2670                 }
2671                 $this->endAtomic( $fname );
2672
2673                 return $res;
2674         }
2675
2676         final public function begin( $fname = __METHOD__, $mode = self::TRANSACTION_EXPLICIT ) {
2677                 // Protect against mismatched atomic section, transaction nesting, and snapshot loss
2678                 if ( $this->mTrxLevel ) {
2679                         if ( $this->mTrxAtomicLevels ) {
2680                                 $levels = implode( ', ', $this->mTrxAtomicLevels );
2681                                 $msg = "$fname: Got explicit BEGIN while atomic section(s) $levels are open.";
2682                                 throw new DBUnexpectedError( $this, $msg );
2683                         } elseif ( !$this->mTrxAutomatic ) {
2684                                 $msg = "$fname: Explicit transaction already active (from {$this->mTrxFname}).";
2685                                 throw new DBUnexpectedError( $this, $msg );
2686                         } else {
2687                                 // @TODO: make this an exception at some point
2688                                 $msg = "$fname: Implicit transaction already active (from {$this->mTrxFname}).";
2689                                 $this->queryLogger->error( $msg );
2690                                 return; // join the main transaction set
2691                         }
2692                 } elseif ( $this->getFlag( self::DBO_TRX ) && $mode !== self::TRANSACTION_INTERNAL ) {
2693                         // @TODO: make this an exception at some point
2694                         $msg = "$fname: Implicit transaction expected (DBO_TRX set).";
2695                         $this->queryLogger->error( $msg );
2696                         return; // let any writes be in the main transaction
2697                 }
2698
2699                 // Avoid fatals if close() was called
2700                 $this->assertOpen();
2701
2702                 $this->doBegin( $fname );
2703                 $this->mTrxTimestamp = microtime( true );
2704                 $this->mTrxFname = $fname;
2705                 $this->mTrxDoneWrites = false;
2706                 $this->mTrxAutomaticAtomic = false;
2707                 $this->mTrxAtomicLevels = [];
2708                 $this->mTrxShortId = sprintf( '%06x', mt_rand( 0, 0xffffff ) );
2709                 $this->mTrxWriteDuration = 0.0;
2710                 $this->mTrxWriteQueryCount = 0;
2711                 $this->mTrxWriteAdjDuration = 0.0;
2712                 $this->mTrxWriteAdjQueryCount = 0;
2713                 $this->mTrxWriteCallers = [];
2714                 // First SELECT after BEGIN will establish the snapshot in REPEATABLE-READ.
2715                 // Get an estimate of the replica DB lag before then, treating estimate staleness
2716                 // as lag itself just to be safe
2717                 $status = $this->getApproximateLagStatus();
2718                 $this->mTrxReplicaLag = $status['lag'] + ( microtime( true ) - $status['since'] );
2719                 // T147697: make explicitTrxActive() return true until begin() finishes. This way, no
2720                 // caller will think its OK to muck around with the transaction just because startAtomic()
2721                 // has not yet completed (e.g. setting mTrxAtomicLevels).
2722                 $this->mTrxAutomatic = ( $mode === self::TRANSACTION_INTERNAL );
2723         }
2724
2725         /**
2726          * Issues the BEGIN command to the database server.
2727          *
2728          * @see Database::begin()
2729          * @param string $fname
2730          */
2731         protected function doBegin( $fname ) {
2732                 $this->query( 'BEGIN', $fname );
2733                 $this->mTrxLevel = 1;
2734         }
2735
2736         final public function commit( $fname = __METHOD__, $flush = '' ) {
2737                 if ( $this->mTrxLevel && $this->mTrxAtomicLevels ) {
2738                         // There are still atomic sections open. This cannot be ignored
2739                         $levels = implode( ', ', $this->mTrxAtomicLevels );
2740                         throw new DBUnexpectedError(
2741                                 $this,
2742                                 "$fname: Got COMMIT while atomic sections $levels are still open."
2743                         );
2744                 }
2745
2746                 if ( $flush === self::FLUSHING_INTERNAL || $flush === self::FLUSHING_ALL_PEERS ) {
2747                         if ( !$this->mTrxLevel ) {
2748                                 return; // nothing to do
2749                         } elseif ( !$this->mTrxAutomatic ) {
2750                                 throw new DBUnexpectedError(
2751                                         $this,
2752                                         "$fname: Flushing an explicit transaction, getting out of sync."
2753                                 );
2754                         }
2755                 } else {
2756                         if ( !$this->mTrxLevel ) {
2757                                 $this->queryLogger->error(
2758                                         "$fname: No transaction to commit, something got out of sync." );
2759                                 return; // nothing to do
2760                         } elseif ( $this->mTrxAutomatic ) {
2761                                 // @TODO: make this an exception at some point
2762                                 $msg = "$fname: Explicit commit of implicit transaction.";
2763                                 $this->queryLogger->error( $msg );
2764                                 return; // wait for the main transaction set commit round
2765                         }
2766                 }
2767
2768                 // Avoid fatals if close() was called
2769                 $this->assertOpen();
2770
2771                 $this->runOnTransactionPreCommitCallbacks();
2772                 $writeTime = $this->pendingWriteQueryDuration( self::ESTIMATE_DB_APPLY );
2773                 $this->doCommit( $fname );
2774                 if ( $this->mTrxDoneWrites ) {
2775                         $this->mLastWriteTime = microtime( true );
2776                         $this->trxProfiler->transactionWritingOut(
2777                                 $this->mServer, $this->mDBname, $this->mTrxShortId, $writeTime );
2778                 }
2779
2780                 $this->runOnTransactionIdleCallbacks( self::TRIGGER_COMMIT );
2781                 $this->runTransactionListenerCallbacks( self::TRIGGER_COMMIT );
2782         }
2783
2784         /**
2785          * Issues the COMMIT command to the database server.
2786          *
2787          * @see Database::commit()
2788          * @param string $fname
2789          */
2790         protected function doCommit( $fname ) {
2791                 if ( $this->mTrxLevel ) {
2792                         $this->query( 'COMMIT', $fname );
2793                         $this->mTrxLevel = 0;
2794                 }
2795         }
2796
2797         final public function rollback( $fname = __METHOD__, $flush = '' ) {
2798                 if ( $flush === self::FLUSHING_INTERNAL || $flush === self::FLUSHING_ALL_PEERS ) {
2799                         if ( !$this->mTrxLevel ) {
2800                                 return; // nothing to do
2801                         }
2802                 } else {
2803                         if ( !$this->mTrxLevel ) {
2804                                 $this->queryLogger->error(
2805                                         "$fname: No transaction to rollback, something got out of sync." );
2806                                 return; // nothing to do
2807                         } elseif ( $this->getFlag( self::DBO_TRX ) ) {
2808                                 throw new DBUnexpectedError(
2809                                         $this,
2810                                         "$fname: Expected mass rollback of all peer databases (DBO_TRX set)."
2811                                 );
2812                         }
2813                 }
2814
2815                 // Avoid fatals if close() was called
2816                 $this->assertOpen();
2817
2818                 $this->doRollback( $fname );
2819                 $this->mTrxAtomicLevels = [];
2820                 if ( $this->mTrxDoneWrites ) {
2821                         $this->trxProfiler->transactionWritingOut(
2822                                 $this->mServer, $this->mDBname, $this->mTrxShortId );
2823                 }
2824
2825                 $this->mTrxIdleCallbacks = []; // clear
2826                 $this->mTrxPreCommitCallbacks = []; // clear
2827                 $this->runOnTransactionIdleCallbacks( self::TRIGGER_ROLLBACK );
2828                 $this->runTransactionListenerCallbacks( self::TRIGGER_ROLLBACK );
2829         }
2830
2831         /**
2832          * Issues the ROLLBACK command to the database server.
2833          *
2834          * @see Database::rollback()
2835          * @param string $fname
2836          */
2837         protected function doRollback( $fname ) {
2838                 if ( $this->mTrxLevel ) {
2839                         # Disconnects cause rollback anyway, so ignore those errors
2840                         $ignoreErrors = true;
2841                         $this->query( 'ROLLBACK', $fname, $ignoreErrors );
2842                         $this->mTrxLevel = 0;
2843                 }
2844         }
2845
2846         public function flushSnapshot( $fname = __METHOD__ ) {
2847                 if ( $this->writesOrCallbacksPending() || $this->explicitTrxActive() ) {
2848                         // This only flushes transactions to clear snapshots, not to write data
2849                         $fnames = implode( ', ', $this->pendingWriteAndCallbackCallers() );
2850                         throw new DBUnexpectedError(
2851                                 $this,
2852                                 "$fname: Cannot flush snapshot because writes are pending ($fnames)."
2853                         );
2854                 }
2855
2856                 $this->commit( $fname, self::FLUSHING_INTERNAL );
2857         }
2858
2859         public function explicitTrxActive() {
2860                 return $this->mTrxLevel && ( $this->mTrxAtomicLevels || !$this->mTrxAutomatic );
2861         }
2862
2863         public function duplicateTableStructure(
2864                 $oldName, $newName, $temporary = false, $fname = __METHOD__
2865         ) {
2866                 throw new RuntimeException( __METHOD__ . ' is not implemented in descendant class' );
2867         }
2868
2869         public function listTables( $prefix = null, $fname = __METHOD__ ) {
2870                 throw new RuntimeException( __METHOD__ . ' is not implemented in descendant class' );
2871         }
2872
2873         public function listViews( $prefix = null, $fname = __METHOD__ ) {
2874                 throw new RuntimeException( __METHOD__ . ' is not implemented in descendant class' );
2875         }
2876
2877         public function timestamp( $ts = 0 ) {
2878                 $t = new ConvertibleTimestamp( $ts );
2879                 // Let errors bubble up to avoid putting garbage in the DB
2880                 return $t->getTimestamp( TS_MW );
2881         }
2882
2883         public function timestampOrNull( $ts = null ) {
2884                 if ( is_null( $ts ) ) {
2885                         return null;
2886                 } else {
2887                         return $this->timestamp( $ts );
2888                 }
2889         }
2890
2891         /**
2892          * Take the result from a query, and wrap it in a ResultWrapper if
2893          * necessary. Boolean values are passed through as is, to indicate success
2894          * of write queries or failure.
2895          *
2896          * Once upon a time, Database::query() returned a bare MySQL result
2897          * resource, and it was necessary to call this function to convert it to
2898          * a wrapper. Nowadays, raw database objects are never exposed to external
2899          * callers, so this is unnecessary in external code.
2900          *
2901          * @param bool|ResultWrapper|resource|object $result
2902          * @return bool|ResultWrapper
2903          */
2904         protected function resultObject( $result ) {
2905                 if ( !$result ) {
2906                         return false;
2907                 } elseif ( $result instanceof ResultWrapper ) {
2908                         return $result;
2909                 } elseif ( $result === true ) {
2910                         // Successful write query
2911                         return $result;
2912                 } else {
2913                         return new ResultWrapper( $this, $result );
2914                 }
2915         }
2916
2917         public function ping( &$rtt = null ) {
2918                 // Avoid hitting the server if it was hit recently
2919                 if ( $this->isOpen() && ( microtime( true ) - $this->lastPing ) < self::PING_TTL ) {
2920                         if ( !func_num_args() || $this->mRTTEstimate > 0 ) {
2921                                 $rtt = $this->mRTTEstimate;
2922                                 return true; // don't care about $rtt
2923                         }
2924                 }
2925
2926                 // This will reconnect if possible or return false if not
2927                 $this->clearFlag( self::DBO_TRX, self::REMEMBER_PRIOR );
2928                 $ok = ( $this->query( self::PING_QUERY, __METHOD__, true ) !== false );
2929                 $this->restoreFlags( self::RESTORE_PRIOR );
2930
2931                 if ( $ok ) {
2932                         $rtt = $this->mRTTEstimate;
2933                 }
2934
2935                 return $ok;
2936         }
2937
2938         /**
2939          * @return bool
2940          */
2941         protected function reconnect() {
2942                 $this->closeConnection();
2943                 $this->mOpened = false;
2944                 $this->mConn = false;
2945                 try {
2946                         $this->open( $this->mServer, $this->mUser, $this->mPassword, $this->mDBname );
2947                         $this->lastPing = microtime( true );
2948                         $ok = true;
2949                 } catch ( DBConnectionError $e ) {
2950                         $ok = false;
2951                 }
2952
2953                 return $ok;
2954         }
2955
2956         public function getSessionLagStatus() {
2957                 return $this->getTransactionLagStatus() ?: $this->getApproximateLagStatus();
2958         }
2959
2960         /**
2961          * Get the replica DB lag when the current transaction started
2962          *
2963          * This is useful when transactions might use snapshot isolation
2964          * (e.g. REPEATABLE-READ in innodb), so the "real" lag of that data
2965          * is this lag plus transaction duration. If they don't, it is still
2966          * safe to be pessimistic. This returns null if there is no transaction.
2967          *
2968          * @return array|null ('lag': seconds or false on error, 'since': UNIX timestamp of BEGIN)
2969          * @since 1.27
2970          */
2971         protected function getTransactionLagStatus() {
2972                 return $this->mTrxLevel
2973                         ? [ 'lag' => $this->mTrxReplicaLag, 'since' => $this->trxTimestamp() ]
2974                         : null;
2975         }
2976
2977         /**
2978          * Get a replica DB lag estimate for this server
2979          *
2980          * @return array ('lag': seconds or false on error, 'since': UNIX timestamp of estimate)
2981          * @since 1.27
2982          */
2983         protected function getApproximateLagStatus() {
2984                 return [
2985                         'lag'   => $this->getLBInfo( 'replica' ) ? $this->getLag() : 0,
2986                         'since' => microtime( true )
2987                 ];
2988         }
2989
2990         /**
2991          * Merge the result of getSessionLagStatus() for several DBs
2992          * using the most pessimistic values to estimate the lag of
2993          * any data derived from them in combination
2994          *
2995          * This is information is useful for caching modules
2996          *
2997          * @see WANObjectCache::set()
2998          * @see WANObjectCache::getWithSetCallback()
2999          *
3000          * @param IDatabase $db1
3001          * @param IDatabase ...
3002          * @return array Map of values:
3003          *   - lag: highest lag of any of the DBs or false on error (e.g. replication stopped)
3004          *   - since: oldest UNIX timestamp of any of the DB lag estimates
3005          *   - pending: whether any of the DBs have uncommitted changes
3006          * @since 1.27
3007          */
3008         public static function getCacheSetOptions( IDatabase $db1 ) {
3009                 $res = [ 'lag' => 0, 'since' => INF, 'pending' => false ];
3010                 foreach ( func_get_args() as $db ) {
3011                         /** @var IDatabase $db */
3012                         $status = $db->getSessionLagStatus();
3013                         if ( $status['lag'] === false ) {
3014                                 $res['lag'] = false;
3015                         } elseif ( $res['lag'] !== false ) {
3016                                 $res['lag'] = max( $res['lag'], $status['lag'] );
3017                         }
3018                         $res['since'] = min( $res['since'], $status['since'] );
3019                         $res['pending'] = $res['pending'] ?: $db->writesPending();
3020                 }
3021
3022                 return $res;
3023         }
3024
3025         public function getLag() {
3026                 return 0;
3027         }
3028
3029         public function maxListLen() {
3030                 return 0;
3031         }
3032
3033         public function encodeBlob( $b ) {
3034                 return $b;
3035         }
3036
3037         public function decodeBlob( $b ) {
3038                 if ( $b instanceof Blob ) {
3039                         $b = $b->fetch();
3040                 }
3041                 return $b;
3042         }
3043
3044         public function setSessionOptions( array $options ) {
3045         }
3046
3047         public function sourceFile(
3048                 $filename,
3049                 callable $lineCallback = null,
3050                 callable $resultCallback = null,
3051                 $fname = false,
3052                 callable $inputCallback = null
3053         ) {
3054                 MediaWiki\suppressWarnings();
3055                 $fp = fopen( $filename, 'r' );
3056                 MediaWiki\restoreWarnings();
3057
3058                 if ( false === $fp ) {
3059                         throw new RuntimeException( "Could not open \"{$filename}\".\n" );
3060                 }
3061
3062                 if ( !$fname ) {
3063                         $fname = __METHOD__ . "( $filename )";
3064                 }
3065
3066                 try {
3067                         $error = $this->sourceStream(
3068                                 $fp, $lineCallback, $resultCallback, $fname, $inputCallback );
3069                 } catch ( Exception $e ) {
3070                         fclose( $fp );
3071                         throw $e;
3072                 }
3073
3074                 fclose( $fp );
3075
3076                 return $error;
3077         }
3078
3079         public function setSchemaVars( $vars ) {
3080                 $this->mSchemaVars = $vars;
3081         }
3082
3083         public function sourceStream(
3084                 $fp,
3085                 callable $lineCallback = null,
3086                 callable $resultCallback = null,
3087                 $fname = __METHOD__,
3088                 callable $inputCallback = null
3089         ) {
3090                 $cmd = '';
3091
3092                 while ( !feof( $fp ) ) {
3093                         if ( $lineCallback ) {
3094                                 call_user_func( $lineCallback );
3095                         }
3096
3097                         $line = trim( fgets( $fp ) );
3098
3099                         if ( $line == '' ) {
3100                                 continue;
3101                         }
3102
3103                         if ( '-' == $line[0] && '-' == $line[1] ) {
3104                                 continue;
3105                         }
3106
3107                         if ( $cmd != '' ) {
3108                                 $cmd .= ' ';
3109                         }
3110
3111                         $done = $this->streamStatementEnd( $cmd, $line );
3112
3113                         $cmd .= "$line\n";
3114
3115                         if ( $done || feof( $fp ) ) {
3116                                 $cmd = $this->replaceVars( $cmd );
3117
3118                                 if ( !$inputCallback || call_user_func( $inputCallback, $cmd ) ) {
3119                                         $res = $this->query( $cmd, $fname );
3120
3121                                         if ( $resultCallback ) {
3122                                                 call_user_func( $resultCallback, $res, $this );
3123                                         }
3124
3125                                         if ( false === $res ) {
3126                                                 $err = $this->lastError();
3127
3128                                                 return "Query \"{$cmd}\" failed with error code \"$err\".\n";
3129                                         }
3130                                 }
3131                                 $cmd = '';
3132                         }
3133                 }
3134
3135                 return true;
3136         }
3137
3138         /**
3139          * Called by sourceStream() to check if we've reached a statement end
3140          *
3141          * @param string &$sql SQL assembled so far
3142          * @param string &$newLine New line about to be added to $sql
3143          * @return bool Whether $newLine contains end of the statement
3144          */
3145         public function streamStatementEnd( &$sql, &$newLine ) {
3146                 if ( $this->delimiter ) {
3147                         $prev = $newLine;
3148                         $newLine = preg_replace(
3149                                 '/' . preg_quote( $this->delimiter, '/' ) . '$/', '', $newLine );
3150                         if ( $newLine != $prev ) {
3151                                 return true;
3152                         }
3153                 }
3154
3155                 return false;
3156         }
3157
3158         /**
3159          * Database independent variable replacement. Replaces a set of variables
3160          * in an SQL statement with their contents as given by $this->getSchemaVars().
3161          *
3162          * Supports '{$var}' `{$var}` and / *$var* / (without the spaces) style variables.
3163          *
3164          * - '{$var}' should be used for text and is passed through the database's
3165          *   addQuotes method.
3166          * - `{$var}` should be used for identifiers (e.g. table and database names).
3167          *   It is passed through the database's addIdentifierQuotes method which
3168          *   can be overridden if the database uses something other than backticks.
3169          * - / *_* / or / *$wgDBprefix* / passes the name that follows through the
3170          *   database's tableName method.
3171          * - / *i* / passes the name that follows through the database's indexName method.
3172          * - In all other cases, / *$var* / is left unencoded. Except for table options,
3173          *   its use should be avoided. In 1.24 and older, string encoding was applied.
3174          *
3175          * @param string $ins SQL statement to replace variables in
3176          * @return string The new SQL statement with variables replaced
3177          */
3178         protected function replaceVars( $ins ) {
3179                 $vars = $this->getSchemaVars();
3180                 return preg_replace_callback(
3181                         '!
3182                                 /\* (\$wgDBprefix|[_i]) \*/ (\w*) | # 1-2. tableName, indexName
3183                                 \'\{\$ (\w+) }\'                  | # 3. addQuotes
3184                                 `\{\$ (\w+) }`                    | # 4. addIdentifierQuotes
3185                                 /\*\$ (\w+) \*/                     # 5. leave unencoded
3186                         !x',
3187                         function ( $m ) use ( $vars ) {
3188                                 // Note: Because of <https://bugs.php.net/bug.php?id=51881>,
3189                                 // check for both nonexistent keys *and* the empty string.
3190                                 if ( isset( $m[1] ) && $m[1] !== '' ) {
3191                                         if ( $m[1] === 'i' ) {
3192                                                 return $this->indexName( $m[2] );
3193                                         } else {
3194                                                 return $this->tableName( $m[2] );
3195                                         }
3196                                 } elseif ( isset( $m[3] ) && $m[3] !== '' && array_key_exists( $m[3], $vars ) ) {
3197                                         return $this->addQuotes( $vars[$m[3]] );
3198                                 } elseif ( isset( $m[4] ) && $m[4] !== '' && array_key_exists( $m[4], $vars ) ) {
3199                                         return $this->addIdentifierQuotes( $vars[$m[4]] );
3200                                 } elseif ( isset( $m[5] ) && $m[5] !== '' && array_key_exists( $m[5], $vars ) ) {
3201                                         return $vars[$m[5]];
3202                                 } else {
3203                                         return $m[0];
3204                                 }
3205                         },
3206                         $ins
3207                 );
3208         }
3209
3210         /**
3211          * Get schema variables. If none have been set via setSchemaVars(), then
3212          * use some defaults from the current object.
3213          *
3214          * @return array
3215          */
3216         protected function getSchemaVars() {
3217                 if ( $this->mSchemaVars ) {
3218                         return $this->mSchemaVars;
3219                 } else {
3220                         return $this->getDefaultSchemaVars();
3221                 }
3222         }
3223
3224         /**
3225          * Get schema variables to use if none have been set via setSchemaVars().
3226          *
3227          * Override this in derived classes to provide variables for tables.sql
3228          * and SQL patch files.
3229          *
3230          * @return array
3231          */
3232         protected function getDefaultSchemaVars() {
3233                 return [];
3234         }
3235
3236         public function lockIsFree( $lockName, $method ) {
3237                 return true;
3238         }
3239
3240         public function lock( $lockName, $method, $timeout = 5 ) {
3241                 $this->mNamedLocksHeld[$lockName] = 1;
3242
3243                 return true;
3244         }
3245
3246         public function unlock( $lockName, $method ) {
3247                 unset( $this->mNamedLocksHeld[$lockName] );
3248
3249                 return true;
3250         }
3251
3252         public function getScopedLockAndFlush( $lockKey, $fname, $timeout ) {
3253                 if ( $this->writesOrCallbacksPending() ) {
3254                         // This only flushes transactions to clear snapshots, not to write data
3255                         $fnames = implode( ', ', $this->pendingWriteAndCallbackCallers() );
3256                         throw new DBUnexpectedError(
3257                                 $this,
3258                                 "$fname: Cannot flush pre-lock snapshot because writes are pending ($fnames)."
3259                         );
3260                 }
3261
3262                 if ( !$this->lock( $lockKey, $fname, $timeout ) ) {
3263                         return null;
3264                 }
3265
3266                 $unlocker = new ScopedCallback( function () use ( $lockKey, $fname ) {
3267                         if ( $this->trxLevel() ) {
3268                                 // There is a good chance an exception was thrown, causing any early return
3269                                 // from the caller. Let any error handler get a chance to issue rollback().
3270                                 // If there isn't one, let the error bubble up and trigger server-side rollback.
3271                                 $this->onTransactionResolution(
3272                                         function () use ( $lockKey, $fname ) {
3273                                                 $this->unlock( $lockKey, $fname );
3274                                         },
3275                                         $fname
3276                                 );
3277                         } else {
3278                                 $this->unlock( $lockKey, $fname );
3279                         }
3280                 } );
3281
3282                 $this->commit( $fname, self::FLUSHING_INTERNAL );
3283
3284                 return $unlocker;
3285         }
3286
3287         public function namedLocksEnqueue() {
3288                 return false;
3289         }
3290
3291         /**
3292          * Lock specific tables
3293          *
3294          * @param array $read Array of tables to lock for read access
3295          * @param array $write Array of tables to lock for write access
3296          * @param string $method Name of caller
3297          * @param bool $lowPriority Whether to indicate writes to be LOW PRIORITY
3298          * @return bool
3299          */
3300         public function lockTables( $read, $write, $method, $lowPriority = true ) {
3301                 return true;
3302         }
3303
3304         /**
3305          * Unlock specific tables
3306          *
3307          * @param string $method The caller
3308          * @return bool
3309          */
3310         public function unlockTables( $method ) {
3311                 return true;
3312         }
3313
3314         /**
3315          * Delete a table
3316          * @param string $tableName
3317          * @param string $fName
3318          * @return bool|ResultWrapper
3319          * @since 1.18
3320          */
3321         public function dropTable( $tableName, $fName = __METHOD__ ) {
3322                 if ( !$this->tableExists( $tableName, $fName ) ) {
3323                         return false;
3324                 }
3325                 $sql = "DROP TABLE " . $this->tableName( $tableName ) . " CASCADE";
3326
3327                 return $this->query( $sql, $fName );
3328         }
3329
3330         public function getInfinity() {
3331                 return 'infinity';
3332         }
3333
3334         public function encodeExpiry( $expiry ) {
3335                 return ( $expiry == '' || $expiry == 'infinity' || $expiry == $this->getInfinity() )
3336                         ? $this->getInfinity()
3337                         : $this->timestamp( $expiry );
3338         }
3339
3340         public function decodeExpiry( $expiry, $format = TS_MW ) {
3341                 if ( $expiry == '' || $expiry == 'infinity' || $expiry == $this->getInfinity() ) {
3342                         return 'infinity';
3343                 }
3344
3345                 return ConvertibleTimestamp::convert( $format, $expiry );
3346         }
3347
3348         public function setBigSelects( $value = true ) {
3349                 // no-op
3350         }
3351
3352         public function isReadOnly() {
3353                 return ( $this->getReadOnlyReason() !== false );
3354         }
3355
3356         /**
3357          * @return string|bool Reason this DB is read-only or false if it is not
3358          */
3359         protected function getReadOnlyReason() {
3360                 $reason = $this->getLBInfo( 'readOnlyReason' );
3361
3362                 return is_string( $reason ) ? $reason : false;
3363         }
3364
3365         public function setTableAliases( array $aliases ) {
3366                 $this->tableAliases = $aliases;
3367         }
3368
3369         /**
3370          * @return bool Whether a DB user is required to access the DB
3371          * @since 1.28
3372          */
3373         protected function requiresDatabaseUser() {
3374                 return true;
3375         }
3376
3377         /**
3378          * Get the underlying binding handle, mConn
3379          *
3380          * Makes sure that mConn is set (disconnects and ping() failure can unset it).
3381          * This catches broken callers than catch and ignore disconnection exceptions.
3382          * Unlike checking isOpen(), this is safe to call inside of open().
3383          *
3384          * @return resource|object
3385          * @throws DBUnexpectedError
3386          * @since 1.26
3387          */
3388         protected function getBindingHandle() {
3389                 if ( !$this->mConn ) {
3390                         throw new DBUnexpectedError(
3391                                 $this,
3392                                 'DB connection was already closed or the connection dropped.'
3393                         );
3394                 }
3395
3396                 return $this->mConn;
3397         }
3398
3399         /**
3400          * @since 1.19
3401          * @return string
3402          */
3403         public function __toString() {
3404                 return (string)$this->mConn;
3405         }
3406
3407         /**
3408          * Make sure that copies do not share the same client binding handle
3409          * @throws DBConnectionError
3410          */
3411         public function __clone() {
3412                 $this->connLogger->warning(
3413                         "Cloning " . get_class( $this ) . " is not recomended; forking connection:\n" .
3414                         ( new RuntimeException() )->getTraceAsString()
3415                 );
3416
3417                 if ( $this->isOpen() ) {
3418                         // Open a new connection resource without messing with the old one
3419                         $this->mOpened = false;
3420                         $this->mConn = false;
3421                         $this->mTrxEndCallbacks = []; // don't copy
3422                         $this->handleSessionLoss(); // no trx or locks anymore
3423                         $this->open( $this->mServer, $this->mUser, $this->mPassword, $this->mDBname );
3424                         $this->lastPing = microtime( true );
3425                 }
3426         }
3427
3428         /**
3429          * Called by serialize. Throw an exception when DB connection is serialized.
3430          * This causes problems on some database engines because the connection is
3431          * not restored on unserialize.
3432          */
3433         public function __sleep() {
3434                 throw new RuntimeException( 'Database serialization may cause problems, since ' .
3435                         'the connection is not restored on wakeup.' );
3436         }
3437
3438         /**
3439          * Run a few simple sanity checks and close dangling connections
3440          */
3441         public function __destruct() {
3442                 if ( $this->mTrxLevel && $this->mTrxDoneWrites ) {
3443                         trigger_error( "Uncommitted DB writes (transaction from {$this->mTrxFname})." );
3444                 }
3445
3446                 $danglingWriters = $this->pendingWriteAndCallbackCallers();
3447                 if ( $danglingWriters ) {
3448                         $fnames = implode( ', ', $danglingWriters );
3449                         trigger_error( "DB transaction writes or callbacks still pending ($fnames)." );
3450                 }
3451
3452                 if ( $this->mConn ) {
3453                         // Avoid connection leaks for sanity. Normally, resources close at script completion.
3454                         // The connection might already be closed in zend/hhvm by now, so suppress warnings.
3455                         \MediaWiki\suppressWarnings();
3456                         $this->closeConnection();
3457                         \MediaWiki\restoreWarnings();
3458                         $this->mConn = false;
3459                         $this->mOpened = false;
3460                 }
3461         }
3462 }
3463
3464 class_alias( Database::class, 'DatabaseBase' );