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 namespace Wikimedia\Rdbms;
  27
  28 use Psr\Log\LoggerAwareInterface;
  29 use Psr\Log\LoggerInterface;
  30 use Wikimedia\ScopedCallback;
  31 use Wikimedia\Timestamp\ConvertibleTimestamp;
  32 use MediaWiki;
  33 use BagOStuff;
  34 use HashBagOStuff;
  35 use InvalidArgumentException;
  36 use Exception;
  37 use RuntimeException;
  38
  39 /**
  40  * Relational database abstraction object
  41  *
  42  * @ingroup Database
  43  * @since 1.28
  44  */
  45 abstract class Database implements IDatabase, IMaintainableDatabase, LoggerAwareInterface {
  46         /** Number of times to re-try an operation in case of deadlock */
  47         const DEADLOCK_TRIES = 4;
  48         /** Minimum time to wait before retry, in microseconds */
  49         const DEADLOCK_DELAY_MIN = 500000;
  50         /** Maximum time to wait before retry */
  51         const DEADLOCK_DELAY_MAX = 1500000;
  52
  53         /** How long before it is worth doing a dummy query to test the connection */
  54         const PING_TTL = 1.0;
  55         const PING_QUERY = 'SELECT 1 AS ping';
  56
  57         const TINY_WRITE_SEC = 0.010;
  58         const SLOW_WRITE_SEC = 0.500;
  59         const SMALL_WRITE_ROWS = 100;
  60
  61         /** @var string SQL query */
  62         protected $mLastQuery = '';
  63         /** @var float|bool UNIX timestamp of last write query */
  64         protected $mLastWriteTime = false;
  65         /** @var string|bool */
  66         protected $mPHPError = false;
  67         /** @var string */
  68         protected $mServer;
  69         /** @var string */
  70         protected $mUser;
  71         /** @var string */
  72         protected $mPassword;
  73         /** @var string */
  74         protected $mDBname;
  75         /** @var array[] $aliases Map of (table => (dbname, schema, prefix) map) */
  76         protected $tableAliases = [];
  77         /** @var bool Whether this PHP instance is for a CLI script */
  78         protected $cliMode;
  79         /** @var string Agent name for query profiling */
  80         protected $agent;
  81
  82         /** @var BagOStuff APC cache */
  83         protected $srvCache;
  84         /** @var LoggerInterface */
  85         protected $connLogger;
  86         /** @var LoggerInterface */
  87         protected $queryLogger;
  88         /** @var callback Error logging callback */
  89         protected $errorLogger;
  90
  91         /** @var resource|null Database connection */
  92         protected $mConn = null;
  93         /** @var bool */
  94         protected $mOpened = false;
  95
  96         /** @var array[] List of (callable, method name) */
  97         protected $mTrxIdleCallbacks = [];
  98         /** @var array[] List of (callable, method name) */
  99         protected $mTrxPreCommitCallbacks = [];
 100         /** @var array[] List of (callable, method name) */
 101         protected $mTrxEndCallbacks = [];
 102         /** @var callable[] Map of (name => callable) */
 103         protected $mTrxRecurringCallbacks = [];
 104         /** @var bool Whether to suppress triggering of transaction end callbacks */
 105         protected $mTrxEndCallbacksSuppressed = false;
 106
 107         /** @var string */
 108         protected $mTablePrefix = '';
 109         /** @var string */
 110         protected $mSchema = '';
 111         /** @var int */
 112         protected $mFlags;
 113         /** @var array */
 114         protected $mLBInfo = [];
 115         /** @var bool|null */
 116         protected $mDefaultBigSelects = null;
 117         /** @var array|bool */
 118         protected $mSchemaVars = false;
 119         /** @var array */
 120         protected $mSessionVars = [];
 121         /** @var array|null */
 122         protected $preparedArgs;
 123         /** @var string|bool|null Stashed value of html_errors INI setting */
 124         protected $htmlErrors;
 125         /** @var string */
 126         protected $delimiter = ';';
 127         /** @var DatabaseDomain */
 128         protected $currentDomain;
 129
 130         /**
 131          * Either 1 if a transaction is active or 0 otherwise.
 132          * The other Trx fields may not be meaningfull if this is 0.
 133          *
 134          * @var int
 135          */
 136         protected $mTrxLevel = 0;
 137         /**
 138          * Either a short hexidecimal string if a transaction is active or ""
 139          *
 140          * @var string
 141          * @see Database::mTrxLevel
 142          */
 143         protected $mTrxShortId = '';
 144         /**
 145          * The UNIX time that the transaction started. Callers can assume that if
 146          * snapshot isolation is used, then the data is *at least* up to date to that
 147          * point (possibly more up-to-date since the first SELECT defines the snapshot).
 148          *
 149          * @var float|null
 150          * @see Database::mTrxLevel
 151          */
 152         private $mTrxTimestamp = null;
 153         /** @var float Lag estimate at the time of BEGIN */
 154         private $mTrxReplicaLag = null;
 155         /**
 156          * Remembers the function name given for starting the most recent transaction via begin().
 157          * Used to provide additional context for error reporting.
 158          *
 159          * @var string
 160          * @see Database::mTrxLevel
 161          */
 162         private $mTrxFname = null;
 163         /**
 164          * Record if possible write queries were done in the last transaction started
 165          *
 166          * @var bool
 167          * @see Database::mTrxLevel
 168          */
 169         private $mTrxDoneWrites = false;
 170         /**
 171          * Record if the current transaction was started implicitly due to DBO_TRX being set.
 172          *
 173          * @var bool
 174          * @see Database::mTrxLevel
 175          */
 176         private $mTrxAutomatic = false;
 177         /**
 178          * Array of levels of atomicity within transactions
 179          *
 180          * @var array
 181          */
 182         private $mTrxAtomicLevels = [];
 183         /**
 184          * Record if the current transaction was started implicitly by Database::startAtomic
 185          *
 186          * @var bool
 187          */
 188         private $mTrxAutomaticAtomic = false;
 189         /**
 190          * Track the write query callers of the current transaction
 191          *
 192          * @var string[]
 193          */
 194         private $mTrxWriteCallers = [];
 195         /**
 196          * @var float Seconds spent in write queries for the current transaction
 197          */
 198         private $mTrxWriteDuration = 0.0;
 199         /**
 200          * @var int Number of write queries for the current transaction
 201          */
 202         private $mTrxWriteQueryCount = 0;
 203         /**
 204          * @var int Number of rows affected by write queries for the current transaction
 205          */
 206         private $mTrxWriteAffectedRows = 0;
 207         /**
 208          * @var float Like mTrxWriteQueryCount but excludes lock-bound, easy to replicate, queries
 209          */
 210         private $mTrxWriteAdjDuration = 0.0;
 211         /**
 212          * @var int Number of write queries counted in mTrxWriteAdjDuration
 213          */
 214         private $mTrxWriteAdjQueryCount = 0;
 215         /**
 216          * @var float RTT time estimate
 217          */
 218         private $mRTTEstimate = 0.0;
 219
 220         /** @var array Map of (name => 1) for locks obtained via lock() */
 221         private $mNamedLocksHeld = [];
 222         /** @var array Map of (table name => 1) for TEMPORARY tables */
 223         protected $mSessionTempTables = [];
 224
 225         /** @var IDatabase|null Lazy handle to the master DB this server replicates from */
 226         private $lazyMasterHandle;
 227
 228         /** @var float UNIX timestamp */
 229         protected $lastPing = 0.0;
 230
 231         /** @var int[] Prior mFlags values */
 232         private $priorFlags = [];
 233
 234         /** @var object|string Class name or object With profileIn/profileOut methods */
 235         protected $profiler;
 236         /** @var TransactionProfiler */
 237         protected $trxProfiler;
 238
 239         /**
 240          * Constructor and database handle and attempt to connect to the DB server
 241          *
 242          * IDatabase classes should not be constructed directly in external
 243          * code. Database::factory() should be used instead.
 244          *
 245          * @param array $params Parameters passed from Database::factory()
 246          */
 247         function __construct( array $params ) {
 248                 $server = $params['host'];
 249                 $user = $params['user'];
 250                 $password = $params['password'];
 251                 $dbName = $params['dbname'];
 252
 253                 $this->mSchema = $params['schema'];
 254                 $this->mTablePrefix = $params['tablePrefix'];
 255
 256                 $this->cliMode = $params['cliMode'];
 257                 // Agent name is added to SQL queries in a comment, so make sure it can't break out
 258                 $this->agent = str_replace( '/', '-', $params['agent'] );
 259
 260                 $this->mFlags = $params['flags'];
 261                 if ( $this->mFlags & self::DBO_DEFAULT ) {
 262                         if ( $this->cliMode ) {
 263                                 $this->mFlags &= ~self::DBO_TRX;
 264                         } else {
 265                                 $this->mFlags |= self::DBO_TRX;
 266                         }
 267                 }
 268
 269                 $this->mSessionVars = $params['variables'];
 270
 271                 $this->srvCache = isset( $params['srvCache'] )
 272                         ? $params['srvCache']
 273                         : new HashBagOStuff();
 274
 275                 $this->profiler = $params['profiler'];
 276                 $this->trxProfiler = $params['trxProfiler'];
 277                 $this->connLogger = $params['connLogger'];
 278                 $this->queryLogger = $params['queryLogger'];
 279                 $this->errorLogger = $params['errorLogger'];
 280
 281                 // Set initial dummy domain until open() sets the final DB/prefix
 282                 $this->currentDomain = DatabaseDomain::newUnspecified();
 283
 284                 if ( $user ) {
 285                         $this->open( $server, $user, $password, $dbName );
 286                 } elseif ( $this->requiresDatabaseUser() ) {
 287                         throw new InvalidArgumentException( "No database user provided." );
 288                 }
 289
 290                 // Set the domain object after open() sets the relevant fields
 291                 if ( $this->mDBname != '' ) {
 292                         // Domains with server scope but a table prefix are not used by IDatabase classes
 293                         $this->currentDomain = new DatabaseDomain( $this->mDBname, null, $this->mTablePrefix );
 294                 }
 295         }
 296
 297         /**
 298          * Construct a Database subclass instance given a database type and parameters
 299          *
 300          * This also connects to the database immediately upon object construction
 301          *
 302          * @param string $dbType A possible DB type (sqlite, mysql, postgres)
 303          * @param array $p Parameter map with keys:
 304          *   - host : The hostname of the DB server
 305          *   - user : The name of the database user the client operates under
 306          *   - password : The password for the database user
 307          *   - dbname : The name of the database to use where queries do not specify one.
 308          *      The database must exist or an error might be thrown. Setting this to the empty string
 309          *      will avoid any such errors and make the handle have no implicit database scope. This is
 310          *      useful for queries like SHOW STATUS, CREATE DATABASE, or DROP DATABASE. Note that a
 311          *      "database" in Postgres is rougly equivalent to an entire MySQL server. This the domain
 312          *      in which user names and such are defined, e.g. users are database-specific in Postgres.
 313          *   - schema : The database schema to use (if supported). A "schema" in Postgres is roughly
 314          *      equivalent to a "database" in MySQL. Note that MySQL and SQLite do not use schemas.
 315          *   - tablePrefix : Optional table prefix that is implicitly added on to all table names
 316          *      recognized in queries. This can be used in place of schemas for handle site farms.
 317          *   - flags : Optional bitfield of DBO_* constants that define connection, protocol,
 318          *      buffering, and transaction behavior. It is STRONGLY adviced to leave the DBO_DEFAULT
 319          *      flag in place UNLESS this this database simply acts as a key/value store.
 320          *   - driver: Optional name of a specific DB client driver. For MySQL, there is the old
 321          *      'mysql' driver and the newer 'mysqli' driver.
 322          *   - variables: Optional map of session variables to set after connecting. This can be
 323          *      used to adjust lock timeouts or encoding modes and the like.
 324          *   - connLogger: Optional PSR-3 logger interface instance.
 325          *   - queryLogger: Optional PSR-3 logger interface instance.
 326          *   - profiler: Optional class name or object with profileIn()/profileOut() methods.
 327          *      These will be called in query(), using a simplified version of the SQL that also
 328          *      includes the agent as a SQL comment.
 329          *   - trxProfiler: Optional TransactionProfiler instance.
 330          *   - errorLogger: Optional callback that takes an Exception and logs it.
 331          *   - cliMode: Whether to consider the execution context that of a CLI script.
 332          *   - agent: Optional name used to identify the end-user in query profiling/logging.
 333          *   - srvCache: Optional BagOStuff instance to an APC-style cache.
 334          * @return Database|null If the database driver or extension cannot be found
 335          * @throws InvalidArgumentException If the database driver or extension cannot be found
 336          * @since 1.18
 337          */
 338         final public static function factory( $dbType, $p = [] ) {
 339                 static $canonicalDBTypes = [
 340                         'mysql' => [ 'mysqli', 'mysql' ],
 341                         'postgres' => [],
 342                         'sqlite' => [],
 343                         'oracle' => [],
 344                         'mssql' => [],
 345                 ];
 346                 static $classAliases = [
 347                         'DatabaseMssql' => DatabaseMssql::class,
 348                         'DatabaseMysql' => DatabaseMysql::class,
 349                         'DatabaseMysqli' => DatabaseMysqli::class,
 350                         'DatabaseSqlite' => DatabaseSqlite::class,
 351                         'DatabasePostgres' => DatabasePostgres::class
 352                 ];
 353
 354                 $driver = false;
 355                 $dbType = strtolower( $dbType );
 356                 if ( isset( $canonicalDBTypes[$dbType] ) && $canonicalDBTypes[$dbType] ) {
 357                         $possibleDrivers = $canonicalDBTypes[$dbType];
 358                         if ( !empty( $p['driver'] ) ) {
 359                                 if ( in_array( $p['driver'], $possibleDrivers ) ) {
 360                                         $driver = $p['driver'];
 361                                 } else {
 362                                         throw new InvalidArgumentException( __METHOD__ .
 363                                                 " type '$dbType' does not support driver '{$p['driver']}'" );
 364                                 }
 365                         } else {
 366                                 foreach ( $possibleDrivers as $posDriver ) {
 367                                         if ( extension_loaded( $posDriver ) ) {
 368                                                 $driver = $posDriver;
 369                                                 break;
 370                                         }
 371                                 }
 372                         }
 373                 } else {
 374                         $driver = $dbType;
 375                 }
 376
 377                 if ( $driver === false || $driver === '' ) {
 378                         throw new InvalidArgumentException( __METHOD__ .
 379                                 " no viable database extension found for type '$dbType'" );
 380                 }
 381
 382                 $class = 'Database' . ucfirst( $driver );
 383                 if ( isset( $classAliases[$class] ) ) {
 384                         $class = $classAliases[$class];
 385                 }
 386
 387                 if ( class_exists( $class ) && is_subclass_of( $class, IDatabase::class ) ) {
 388                         // Resolve some defaults for b/c
 389                         $p['host'] = isset( $p['host'] ) ? $p['host'] : false;
 390                         $p['user'] = isset( $p['user'] ) ? $p['user'] : false;
 391                         $p['password'] = isset( $p['password'] ) ? $p['password'] : false;
 392                         $p['dbname'] = isset( $p['dbname'] ) ? $p['dbname'] : false;
 393                         $p['flags'] = isset( $p['flags'] ) ? $p['flags'] : 0;
 394                         $p['variables'] = isset( $p['variables'] ) ? $p['variables'] : [];
 395                         $p['tablePrefix'] = isset( $p['tablePrefix'] ) ? $p['tablePrefix'] : '';
 396                         $p['schema'] = isset( $p['schema'] ) ? $p['schema'] : '';
 397                         $p['cliMode'] = isset( $p['cliMode'] ) ? $p['cliMode'] : ( PHP_SAPI === 'cli' );
 398                         $p['agent'] = isset( $p['agent'] ) ? $p['agent'] : '';
 399                         if ( !isset( $p['connLogger'] ) ) {
 400                                 $p['connLogger'] = new \Psr\Log\NullLogger();
 401                         }
 402                         if ( !isset( $p['queryLogger'] ) ) {
 403                                 $p['queryLogger'] = new \Psr\Log\NullLogger();
 404                         }
 405                         $p['profiler'] = isset( $p['profiler'] ) ? $p['profiler'] : null;
 406                         if ( !isset( $p['trxProfiler'] ) ) {
 407                                 $p['trxProfiler'] = new TransactionProfiler();
 408                         }
 409                         if ( !isset( $p['errorLogger'] ) ) {
 410                                 $p['errorLogger'] = function ( Exception $e ) {
 411                                         trigger_error( get_class( $e ) . ': ' . $e->getMessage(), E_USER_WARNING );
 412                                 };
 413                         }
 414
 415                         $conn = new $class( $p );
 416                 } else {
 417                         $conn = null;
 418                 }
 419
 420                 return $conn;
 421         }
 422
 423         /**
 424          * Set the PSR-3 logger interface to use for query logging. (The logger
 425          * interfaces for connection logging and error logging can be set with the
 426          * constructor.)
 427          *
 428          * @param LoggerInterface $logger
 429          */
 430         public function setLogger( LoggerInterface $logger ) {
 431                 $this->queryLogger = $logger;
 432         }
 433
 434         public function getServerInfo() {
 435                 return $this->getServerVersion();
 436         }
 437
 438         public function bufferResults( $buffer = null ) {
 439                 $res = !$this->getFlag( self::DBO_NOBUFFER );
 440                 if ( $buffer !== null ) {
 441                         $buffer
 442                                 ? $this->clearFlag( self::DBO_NOBUFFER )
 443                                 : $this->setFlag( self::DBO_NOBUFFER );
 444                 }
 445
 446                 return $res;
 447         }
 448
 449         /**
 450          * Turns on (false) or off (true) the automatic generation and sending
 451          * of a "we're sorry, but there has been a database error" page on
 452          * database errors. Default is on (false). When turned off, the
 453          * code should use lastErrno() and lastError() to handle the
 454          * situation as appropriate.
 455          *
 456          * Do not use this function outside of the Database classes.
 457          *
 458          * @param null|bool $ignoreErrors
 459          * @return bool The previous value of the flag.
 460          */
 461         protected function ignoreErrors( $ignoreErrors = null ) {
 462                 $res = $this->getFlag( self::DBO_IGNORE );
 463                 if ( $ignoreErrors !== null ) {
 464                         $ignoreErrors
 465                                 ? $this->setFlag( self::DBO_IGNORE )
 466                                 : $this->clearFlag( self::DBO_IGNORE );
 467                 }
 468
 469                 return $res;
 470         }
 471
 472         public function trxLevel() {
 473                 return $this->mTrxLevel;
 474         }
 475
 476         public function trxTimestamp() {
 477                 return $this->mTrxLevel ? $this->mTrxTimestamp : null;
 478         }
 479
 480         public function tablePrefix( $prefix = null ) {
 481                 $old = $this->mTablePrefix;
 482                 if ( $prefix !== null ) {
 483                         $this->mTablePrefix = $prefix;
 484                         $this->currentDomain = ( $this->mDBname != '' )
 485                                 ? new DatabaseDomain( $this->mDBname, null, $this->mTablePrefix )
 486                                 : DatabaseDomain::newUnspecified();
 487                 }
 488
 489                 return $old;
 490         }
 491
 492         public function dbSchema( $schema = null ) {
 493                 $old = $this->mSchema;
 494                 if ( $schema !== null ) {
 495                         $this->mSchema = $schema;
 496                 }
 497
 498                 return $old;
 499         }
 500
 501         public function getLBInfo( $name = null ) {
 502                 if ( is_null( $name ) ) {
 503                         return $this->mLBInfo;
 504                 } else {
 505                         if ( array_key_exists( $name, $this->mLBInfo ) ) {
 506                                 return $this->mLBInfo[$name];
 507                         } else {
 508                                 return null;
 509                         }
 510                 }
 511         }
 512
 513         public function setLBInfo( $name, $value = null ) {
 514                 if ( is_null( $value ) ) {
 515                         $this->mLBInfo = $name;
 516                 } else {
 517                         $this->mLBInfo[$name] = $value;
 518                 }
 519         }
 520
 521         public function setLazyMasterHandle( IDatabase $conn ) {
 522                 $this->lazyMasterHandle = $conn;
 523         }
 524
 525         /**
 526          * @return IDatabase|null
 527          * @see setLazyMasterHandle()
 528          * @since 1.27
 529          */
 530         protected function getLazyMasterHandle() {
 531                 return $this->lazyMasterHandle;
 532         }
 533
 534         public function implicitGroupby() {
 535                 return true;
 536         }
 537
 538         public function implicitOrderby() {
 539                 return true;
 540         }
 541
 542         public function lastQuery() {
 543                 return $this->mLastQuery;
 544         }
 545
 546         public function doneWrites() {
 547                 return (bool)$this->mLastWriteTime;
 548         }
 549
 550         public function lastDoneWrites() {
 551                 return $this->mLastWriteTime ?: false;
 552         }
 553
 554         public function writesPending() {
 555                 return $this->mTrxLevel && $this->mTrxDoneWrites;
 556         }
 557
 558         public function writesOrCallbacksPending() {
 559                 return $this->mTrxLevel && (
 560                         $this->mTrxDoneWrites || $this->mTrxIdleCallbacks || $this->mTrxPreCommitCallbacks
 561                 );
 562         }
 563
 564         public function pendingWriteQueryDuration( $type = self::ESTIMATE_TOTAL ) {
 565                 if ( !$this->mTrxLevel ) {
 566                         return false;
 567                 } elseif ( !$this->mTrxDoneWrites ) {
 568                         return 0.0;
 569                 }
 570
 571                 switch ( $type ) {
 572                         case self::ESTIMATE_DB_APPLY:
 573                                 $this->ping( $rtt );
 574                                 $rttAdjTotal = $this->mTrxWriteAdjQueryCount * $rtt;
 575                                 $applyTime = max( $this->mTrxWriteAdjDuration - $rttAdjTotal, 0 );
 576                                 // For omitted queries, make them count as something at least
 577                                 $omitted = $this->mTrxWriteQueryCount - $this->mTrxWriteAdjQueryCount;
 578                                 $applyTime += self::TINY_WRITE_SEC * $omitted;
 579
 580                                 return $applyTime;
 581                         default: // everything
 582                                 return $this->mTrxWriteDuration;
 583                 }
 584         }
 585
 586         public function pendingWriteCallers() {
 587                 return $this->mTrxLevel ? $this->mTrxWriteCallers : [];
 588         }
 589
 590         public function pendingWriteRowsAffected() {
 591                 return $this->mTrxWriteAffectedRows;
 592         }
 593
 594         /**
 595          * Get the list of method names that have pending write queries or callbacks
 596          * for this transaction
 597          *
 598          * @return array
 599          */
 600         protected function pendingWriteAndCallbackCallers() {
 601                 if ( !$this->mTrxLevel ) {
 602                         return [];
 603                 }
 604
 605                 $fnames = $this->mTrxWriteCallers;
 606                 foreach ( [
 607                         $this->mTrxIdleCallbacks,
 608                         $this->mTrxPreCommitCallbacks,
 609                         $this->mTrxEndCallbacks
 610                 ] as $callbacks ) {
 611                         foreach ( $callbacks as $callback ) {
 612                                 $fnames[] = $callback[1];
 613                         }
 614                 }
 615
 616                 return $fnames;
 617         }
 618
 619         public function isOpen() {
 620                 return $this->mOpened;
 621         }
 622
 623         public function setFlag( $flag, $remember = self::REMEMBER_NOTHING ) {
 624                 if ( $remember === self::REMEMBER_PRIOR ) {
 625                         array_push( $this->priorFlags, $this->mFlags );
 626                 }
 627                 $this->mFlags |= $flag;
 628         }
 629
 630         public function clearFlag( $flag, $remember = self::REMEMBER_NOTHING ) {
 631                 if ( $remember === self::REMEMBER_PRIOR ) {
 632                         array_push( $this->priorFlags, $this->mFlags );
 633                 }
 634                 $this->mFlags &= ~$flag;
 635         }
 636
 637         public function restoreFlags( $state = self::RESTORE_PRIOR ) {
 638                 if ( !$this->priorFlags ) {
 639                         return;
 640                 }
 641
 642                 if ( $state === self::RESTORE_INITIAL ) {
 643                         $this->mFlags = reset( $this->priorFlags );
 644                         $this->priorFlags = [];
 645                 } else {
 646                         $this->mFlags = array_pop( $this->priorFlags );
 647                 }
 648         }
 649
 650         public function getFlag( $flag ) {
 651                 return !!( $this->mFlags & $flag );
 652         }
 653
 654         /**
 655          * @param string $name Class field name
 656          * @return mixed
 657          * @deprecated Since 1.28
 658          */
 659         public function getProperty( $name ) {
 660                 return $this->$name;
 661         }
 662
 663         public function getDomainID() {
 664                 return $this->currentDomain->getId();
 665         }
 666
 667         final public function getWikiID() {
 668                 return $this->getDomainID();
 669         }
 670
 671         /**
 672          * Get information about an index into an object
 673          * @param string $table Table name
 674          * @param string $index Index name
 675          * @param string $fname Calling function name
 676          * @return mixed Database-specific index description class or false if the index does not exist
 677          */
 678         abstract function indexInfo( $table, $index, $fname = __METHOD__ );
 679
 680         /**
 681          * Wrapper for addslashes()
 682          *
 683          * @param string $s String to be slashed.
 684          * @return string Slashed string.
 685          */
 686         abstract function strencode( $s );
 687
 688         /**
 689          * Set a custom error handler for logging errors during database connection
 690          */
 691         protected function installErrorHandler() {
 692                 $this->mPHPError = false;
 693                 $this->htmlErrors = ini_set( 'html_errors', '0' );
 694                 set_error_handler( [ $this, 'connectionErrorLogger' ] );
 695         }
 696
 697         /**
 698          * Restore the previous error handler and return the last PHP error for this DB
 699          *
 700          * @return bool|string
 701          */
 702         protected function restoreErrorHandler() {
 703                 restore_error_handler();
 704                 if ( $this->htmlErrors !== false ) {
 705                         ini_set( 'html_errors', $this->htmlErrors );
 706                 }
 707
 708                 return $this->getLastPHPError();
 709         }
 710
 711         /**
 712          * @return string|bool Last PHP error for this DB (typically connection errors)
 713          */
 714         protected function getLastPHPError() {
 715                 if ( $this->mPHPError ) {
 716                         $error = preg_replace( '!\[<a.*</a>\]!', '', $this->mPHPError );
 717                         $error = preg_replace( '!^.*?:\s?(.*)$!', '$1', $error );
 718
 719                         return $error;
 720                 }
 721
 722                 return false;
 723         }
 724
 725         /**
 726          * Error handler for logging errors during database connection
 727          * This method should not be used outside of Database classes
 728          *
 729          * @param int $errno
 730          * @param string $errstr
 731          */
 732         public function connectionErrorLogger( $errno, $errstr ) {
 733                 $this->mPHPError = $errstr;
 734         }
 735
 736         /**
 737          * Create a log context to pass to PSR-3 logger functions.
 738          *
 739          * @param array $extras Additional data to add to context
 740          * @return array
 741          */
 742         protected function getLogContext( array $extras = [] ) {
 743                 return array_merge(
 744                         [
 745                                 'db_server' => $this->mServer,
 746                                 'db_name' => $this->mDBname,
 747                                 'db_user' => $this->mUser,
 748                         ],
 749                         $extras
 750                 );
 751         }
 752
 753         public function close() {
 754                 if ( $this->mConn ) {
 755                         if ( $this->trxLevel() ) {
 756                                 $this->commit( __METHOD__, self::FLUSHING_INTERNAL );
 757                         }
 758
 759                         $closed = $this->closeConnection();
 760                         $this->mConn = false;
 761                 } elseif (
 762                         $this->mTrxIdleCallbacks ||
 763                         $this->mTrxPreCommitCallbacks ||
 764                         $this->mTrxEndCallbacks
 765                 ) { // sanity
 766                         throw new RuntimeException( "Transaction callbacks still pending." );
 767                 } else {
 768                         $closed = true;
 769                 }
 770                 $this->mOpened = false;
 771
 772                 return $closed;
 773         }
 774
 775         /**
 776          * Make sure isOpen() returns true as a sanity check
 777          *
 778          * @throws DBUnexpectedError
 779          */
 780         protected function assertOpen() {
 781                 if ( !$this->isOpen() ) {
 782                         throw new DBUnexpectedError( $this, "DB connection was already closed." );
 783                 }
 784         }
 785
 786         /**
 787          * Closes underlying database connection
 788          * @since 1.20
 789          * @return bool Whether connection was closed successfully
 790          */
 791         abstract protected function closeConnection();
 792
 793         public function reportConnectionError( $error = 'Unknown error' ) {
 794                 $myError = $this->lastError();
 795                 if ( $myError ) {
 796                         $error = $myError;
 797                 }
 798
 799                 # New method
 800                 throw new DBConnectionError( $this, $error );
 801         }
 802
 803         /**
 804          * The DBMS-dependent part of query()
 805          *
 806          * @param string $sql SQL query.
 807          * @return ResultWrapper|bool Result object to feed to fetchObject,
 808          *   fetchRow, ...; or false on failure
 809          */
 810         abstract protected function doQuery( $sql );
 811
 812         /**
 813          * Determine whether a query writes to the DB.
 814          * Should return true if unsure.
 815          *
 816          * @param string $sql
 817          * @return bool
 818          */
 819         protected function isWriteQuery( $sql ) {
 820                 return !preg_match(
 821                         '/^(?:SELECT|BEGIN|ROLLBACK|COMMIT|SET|SHOW|EXPLAIN|\(SELECT)\b/i', $sql );
 822         }
 823
 824         /**
 825          * @param string $sql
 826          * @return string|null
 827          */
 828         protected function getQueryVerb( $sql ) {
 829                 return preg_match( '/^\s*([a-z]+)/i', $sql, $m ) ? strtoupper( $m[1] ) : null;
 830         }
 831
 832         /**
 833          * Determine whether a SQL statement is sensitive to isolation level.
 834          * A SQL statement is considered transactable if its result could vary
 835          * depending on the transaction isolation level. Operational commands
 836          * such as 'SET' and 'SHOW' are not considered to be transactable.
 837          *
 838          * @param string $sql
 839          * @return bool
 840          */
 841         protected function isTransactableQuery( $sql ) {
 842                 return !in_array(
 843                         $this->getQueryVerb( $sql ),
 844                         [ 'BEGIN', 'COMMIT', 'ROLLBACK', 'SHOW', 'SET', 'CREATE', 'ALTER' ],
 845                         true
 846                 );
 847         }
 848
 849         /**
 850          * @param string $sql A SQL query
 851          * @return bool Whether $sql is SQL for TEMPORARY table operation
 852          */
 853         protected function registerTempTableOperation( $sql ) {
 854                 if ( preg_match(
 855                         '/^CREATE\s+TEMPORARY\s+TABLE\s+(?:IF\s+NOT\s+EXISTS\s+)?[`"\']?(\w+)[`"\']?/i',
 856                         $sql,
 857                         $matches
 858                 ) ) {
 859                         $this->mSessionTempTables[$matches[1]] = 1;
 860
 861                         return true;
 862                 } elseif ( preg_match(
 863                         '/^DROP\s+(?:TEMPORARY\s+)?TABLE\s+(?:IF\s+EXISTS\s+)?[`"\']?(\w+)[`"\']?/i',
 864                         $sql,
 865                         $matches
 866                 ) ) {
 867                         $isTemp = isset( $this->mSessionTempTables[$matches[1]] );
 868                         unset( $this->mSessionTempTables[$matches[1]] );
 869
 870                         return $isTemp;
 871                 } elseif ( preg_match(
 872                         '/^TRUNCATE\s+(?:TEMPORARY\s+)?TABLE\s+(?:IF\s+EXISTS\s+)?[`"\']?(\w+)[`"\']?/i',
 873                         $sql,
 874                         $matches
 875                 ) ) {
 876                         return isset( $this->mSessionTempTables[$matches[1]] );
 877                 } elseif ( preg_match(
 878                         '/^(?:INSERT\s+(?:\w+\s+)?INTO|UPDATE|DELETE\s+FROM)\s+[`"\']?(\w+)[`"\']?/i',
 879                         $sql,
 880                         $matches
 881                 ) ) {
 882                         return isset( $this->mSessionTempTables[$matches[1]] );
 883                 }
 884
 885                 return false;
 886         }
 887
 888         public function query( $sql, $fname = __METHOD__, $tempIgnore = false ) {
 889                 $priorWritesPending = $this->writesOrCallbacksPending();
 890                 $this->mLastQuery = $sql;
 891
 892                 $isWrite = $this->isWriteQuery( $sql );
 893                 if ( $isWrite ) {
 894                         $isNonTempWrite = !$this->registerTempTableOperation( $sql );
 895                 } else {
 896                         $isNonTempWrite = false;
 897                 }
 898
 899                 if ( $isWrite ) {
 900                         # In theory, non-persistent writes are allowed in read-only mode, but due to things
 901                         # like https://bugs.mysql.com/bug.php?id=33669 that might not work anyway...
 902                         $reason = $this->getReadOnlyReason();
 903                         if ( $reason !== false ) {
 904                                 throw new DBReadOnlyError( $this, "Database is read-only: $reason" );
 905                         }
 906                         # Set a flag indicating that writes have been done
 907                         $this->mLastWriteTime = microtime( true );
 908                 }
 909
 910                 # Add trace comment to the begin of the sql string, right after the operator.
 911                 # Or, for one-word queries (like "BEGIN" or COMMIT") add it to the end (T44598)
 912                 $commentedSql = preg_replace( '/\s|$/', " /* $fname {$this->agent} */ ", $sql, 1 );
 913
 914                 # Start implicit transactions that wrap the request if DBO_TRX is enabled
 915                 if ( !$this->mTrxLevel && $this->getFlag( self::DBO_TRX )
 916                         && $this->isTransactableQuery( $sql )
 917                 ) {
 918                         $this->begin( __METHOD__ . " ($fname)", self::TRANSACTION_INTERNAL );
 919                         $this->mTrxAutomatic = true;
 920                 }
 921
 922                 # Keep track of whether the transaction has write queries pending
 923                 if ( $this->mTrxLevel && !$this->mTrxDoneWrites && $isWrite ) {
 924                         $this->mTrxDoneWrites = true;
 925                         $this->trxProfiler->transactionWritingIn(
 926                                 $this->mServer, $this->mDBname, $this->mTrxShortId );
 927                 }
 928
 929                 if ( $this->getFlag( self::DBO_DEBUG ) ) {
 930                         $this->queryLogger->debug( "{$this->mDBname} {$commentedSql}" );
 931                 }
 932
 933                 # Avoid fatals if close() was called
 934                 $this->assertOpen();
 935
 936                 # Send the query to the server
 937                 $ret = $this->doProfiledQuery( $sql, $commentedSql, $isNonTempWrite, $fname );
 938
 939                 # Try reconnecting if the connection was lost
 940                 if ( false === $ret && $this->wasErrorReissuable() ) {
 941                         $recoverable = $this->canRecoverFromDisconnect( $sql, $priorWritesPending );
 942                         # Stash the last error values before anything might clear them
 943                         $lastError = $this->lastError();
 944                         $lastErrno = $this->lastErrno();
 945                         # Update state tracking to reflect transaction loss due to disconnection
 946                         $this->handleSessionLoss();
 947                         if ( $this->reconnect() ) {
 948                                 $msg = __METHOD__ . ": lost connection to {$this->getServer()}; reconnected";
 949                                 $this->connLogger->warning( $msg );
 950                                 $this->queryLogger->warning(
 951                                         "$msg:\n" . ( new RuntimeException() )->getTraceAsString() );
 952
 953                                 if ( !$recoverable ) {
 954                                         # Callers may catch the exception and continue to use the DB
 955                                         $this->reportQueryError( $lastError, $lastErrno, $sql, $fname );
 956                                 } else {
 957                                         # Should be safe to silently retry the query
 958                                         $ret = $this->doProfiledQuery( $sql, $commentedSql, $isNonTempWrite, $fname );
 959                                 }
 960                         } else {
 961                                 $msg = __METHOD__ . ": lost connection to {$this->getServer()} permanently";
 962                                 $this->connLogger->error( $msg );
 963                         }
 964                 }
 965
 966                 if ( false === $ret ) {
 967                         # Deadlocks cause the entire transaction to abort, not just the statement.
 968                         # https://dev.mysql.com/doc/refman/5.7/en/innodb-error-handling.html
 969                         # https://www.postgresql.org/docs/9.1/static/explicit-locking.html
 970                         if ( $this->wasDeadlock() ) {
 971                                 if ( $this->explicitTrxActive() || $priorWritesPending ) {
 972                                         $tempIgnore = false; // not recoverable
 973                                 }
 974                                 # Update state tracking to reflect transaction loss
 975                                 $this->handleSessionLoss();
 976                         }
 977
 978                         $this->reportQueryError(
 979                                 $this->lastError(), $this->lastErrno(), $sql, $fname, $tempIgnore );
 980                 }
 981
 982                 $res = $this->resultObject( $ret );
 983
 984                 return $res;
 985         }
 986
 987         /**
 988          * Helper method for query() that handles profiling and logging and sends
 989          * the query to doQuery()
 990          *
 991          * @param string $sql Original SQL query
 992          * @param string $commentedSql SQL query with debugging/trace comment
 993          * @param bool $isWrite Whether the query is a (non-temporary) write operation
 994          * @param string $fname Name of the calling function
 995          * @return bool|ResultWrapper True for a successful write query, ResultWrapper
 996          *     object for a successful read query, or false on failure
 997          */
 998         private function doProfiledQuery( $sql, $commentedSql, $isWrite, $fname ) {
 999                 $isMaster = !is_null( $this->getLBInfo( 'master' ) );
1000                 # generalizeSQL() will probably cut down the query to reasonable
1001                 # logging size most of the time. The substr is really just a sanity check.
1002                 if ( $isMaster ) {
1003                         $queryProf = 'query-m: ' . substr( self::generalizeSQL( $sql ), 0, 255 );
1004                 } else {
1005                         $queryProf = 'query: ' . substr( self::generalizeSQL( $sql ), 0, 255 );
1006                 }
1007
1008                 # Include query transaction state
1009                 $queryProf .= $this->mTrxShortId ? " [TRX#{$this->mTrxShortId}]" : "";
1010
1011                 $startTime = microtime( true );
1012                 if ( $this->profiler ) {
1013                         call_user_func( [ $this->profiler, 'profileIn' ], $queryProf );
1014                 }
1015                 $ret = $this->doQuery( $commentedSql );
1016                 if ( $this->profiler ) {
1017                         call_user_func( [ $this->profiler, 'profileOut' ], $queryProf );
1018                 }
1019                 $queryRuntime = max( microtime( true ) - $startTime, 0.0 );
1020
1021                 unset( $queryProfSection ); // profile out (if set)
1022
1023                 if ( $ret !== false ) {
1024                         $this->lastPing = $startTime;
1025                         if ( $isWrite && $this->mTrxLevel ) {
1026                                 $this->updateTrxWriteQueryTime( $sql, $queryRuntime, $this->affectedRows() );
1027                                 $this->mTrxWriteCallers[] = $fname;
1028                         }
1029                 }
1030
1031                 if ( $sql === self::PING_QUERY ) {
1032                         $this->mRTTEstimate = $queryRuntime;
1033                 }
1034
1035                 $this->trxProfiler->recordQueryCompletion(
1036                         $queryProf, $startTime, $isWrite, $this->affectedRows()
1037                 );
1038                 $this->queryLogger->debug( $sql, [
1039                         'method' => $fname,
1040                         'master' => $isMaster,
1041                         'runtime' => $queryRuntime,
1042                 ] );
1043
1044                 return $ret;
1045         }
1046
1047         /**
1048          * Update the estimated run-time of a query, not counting large row lock times
1049          *
1050          * LoadBalancer can be set to rollback transactions that will create huge replication
1051          * lag. It bases this estimate off of pendingWriteQueryDuration(). Certain simple
1052          * queries, like inserting a row can take a long time due to row locking. This method
1053          * uses some simple heuristics to discount those cases.
1054          *
1055          * @param string $sql A SQL write query
1056          * @param float $runtime Total runtime, including RTT
1057          * @param int $affected Affected row count
1058          */
1059         private function updateTrxWriteQueryTime( $sql, $runtime, $affected ) {
1060                 // Whether this is indicative of replica DB runtime (except for RBR or ws_repl)
1061                 $indicativeOfReplicaRuntime = true;
1062                 if ( $runtime > self::SLOW_WRITE_SEC ) {
1063                         $verb = $this->getQueryVerb( $sql );
1064                         // insert(), upsert(), replace() are fast unless bulky in size or blocked on locks
1065                         if ( $verb === 'INSERT' ) {
1066                                 $indicativeOfReplicaRuntime = $this->affectedRows() > self::SMALL_WRITE_ROWS;
1067                         } elseif ( $verb === 'REPLACE' ) {
1068                                 $indicativeOfReplicaRuntime = $this->affectedRows() > self::SMALL_WRITE_ROWS / 2;
1069                         }
1070                 }
1071
1072                 $this->mTrxWriteDuration += $runtime;
1073                 $this->mTrxWriteQueryCount += 1;
1074                 $this->mTrxWriteAffectedRows += $affected;
1075                 if ( $indicativeOfReplicaRuntime ) {
1076                         $this->mTrxWriteAdjDuration += $runtime;
1077                         $this->mTrxWriteAdjQueryCount += 1;
1078                 }
1079         }
1080
1081         /**
1082          * Determine whether or not it is safe to retry queries after a database
1083          * connection is lost
1084          *
1085          * @param string $sql SQL query
1086          * @param bool $priorWritesPending Whether there is a transaction open with
1087          *     possible write queries or transaction pre-commit/idle callbacks
1088          *     waiting on it to finish.
1089          * @return bool True if it is safe to retry the query, false otherwise
1090          */
1091         private function canRecoverFromDisconnect( $sql, $priorWritesPending ) {
1092                 # Transaction dropped; this can mean lost writes, or REPEATABLE-READ snapshots.
1093                 # Dropped connections also mean that named locks are automatically released.
1094                 # Only allow error suppression in autocommit mode or when the lost transaction
1095                 # didn't matter anyway (aside from DBO_TRX snapshot loss).
1096                 if ( $this->mNamedLocksHeld ) {
1097                         return false; // possible critical section violation
1098                 } elseif ( $sql === 'COMMIT' ) {
1099                         return !$priorWritesPending; // nothing written anyway? (T127428)
1100                 } elseif ( $sql === 'ROLLBACK' ) {
1101                         return true; // transaction lost...which is also what was requested :)
1102                 } elseif ( $this->explicitTrxActive() ) {
1103                         return false; // don't drop atomocity
1104                 } elseif ( $priorWritesPending ) {
1105                         return false; // prior writes lost from implicit transaction
1106                 }
1107
1108                 return true;
1109         }
1110
1111         /**
1112          * Clean things up after transaction loss due to disconnection
1113          *
1114          * @return null|Exception
1115          */
1116         private function handleSessionLoss() {
1117                 $this->mTrxLevel = 0;
1118                 $this->mTrxIdleCallbacks = []; // T67263
1119                 $this->mTrxPreCommitCallbacks = []; // T67263
1120                 $this->mSessionTempTables = [];
1121                 $this->mNamedLocksHeld = [];
1122                 try {
1123                         // Handle callbacks in mTrxEndCallbacks
1124                         $this->runOnTransactionIdleCallbacks( self::TRIGGER_ROLLBACK );
1125                         $this->runTransactionListenerCallbacks( self::TRIGGER_ROLLBACK );
1126                         return null;
1127                 } catch ( Exception $e ) {
1128                         // Already logged; move on...
1129                         return $e;
1130                 }
1131         }
1132
1133         public function reportQueryError( $error, $errno, $sql, $fname, $tempIgnore = false ) {
1134                 if ( $this->ignoreErrors() || $tempIgnore ) {
1135                         $this->queryLogger->debug( "SQL ERROR (ignored): $error\n" );
1136                 } else {
1137                         $sql1line = mb_substr( str_replace( "\n", "\\n", $sql ), 0, 5 * 1024 );
1138                         $this->queryLogger->error(
1139                                 "{fname}\t{db_server}\t{errno}\t{error}\t{sql1line}",
1140                                 $this->getLogContext( [
1141                                         'method' => __METHOD__,
1142                                         'errno' => $errno,
1143                                         'error' => $error,
1144                                         'sql1line' => $sql1line,
1145                                         'fname' => $fname,
1146                                 ] )
1147                         );
1148                         $this->queryLogger->debug( "SQL ERROR: " . $error . "\n" );
1149                         throw new DBQueryError( $this, $error, $errno, $sql, $fname );
1150                 }
1151         }
1152
1153         public function freeResult( $res ) {
1154         }
1155
1156         public function selectField(
1157                 $table, $var, $cond = '', $fname = __METHOD__, $options = [], $join_conds = []
1158         ) {
1159                 if ( $var === '*' ) { // sanity
1160                         throw new DBUnexpectedError( $this, "Cannot use a * field: got '$var'" );
1161                 }
1162
1163                 if ( !is_array( $options ) ) {
1164                         $options = [ $options ];
1165                 }
1166
1167                 $options['LIMIT'] = 1;
1168
1169                 $res = $this->select( $table, $var, $cond, $fname, $options, $join_conds );
1170                 if ( $res === false || !$this->numRows( $res ) ) {
1171                         return false;
1172                 }
1173
1174                 $row = $this->fetchRow( $res );
1175
1176                 if ( $row !== false ) {
1177                         return reset( $row );
1178                 } else {
1179                         return false;
1180                 }
1181         }
1182
1183         public function selectFieldValues(
1184                 $table, $var, $cond = '', $fname = __METHOD__, $options = [], $join_conds = []
1185         ) {
1186                 if ( $var === '*' ) { // sanity
1187                         throw new DBUnexpectedError( $this, "Cannot use a * field" );
1188                 } elseif ( !is_string( $var ) ) { // sanity
1189                         throw new DBUnexpectedError( $this, "Cannot use an array of fields" );
1190                 }
1191
1192                 if ( !is_array( $options ) ) {
1193                         $options = [ $options ];
1194                 }
1195
1196                 $res = $this->select( $table, $var, $cond, $fname, $options, $join_conds );
1197                 if ( $res === false ) {
1198                         return false;
1199                 }
1200
1201                 $values = [];
1202                 foreach ( $res as $row ) {
1203                         $values[] = $row->$var;
1204                 }
1205
1206                 return $values;
1207         }
1208
1209         /**
1210          * Returns an optional USE INDEX clause to go after the table, and a
1211          * string to go at the end of the query.
1212          *
1213          * @param array $options Associative array of options to be turned into
1214          *   an SQL query, valid keys are listed in the function.
1215          * @return array
1216          * @see Database::select()
1217          */
1218         protected function makeSelectOptions( $options ) {
1219                 $preLimitTail = $postLimitTail = '';
1220                 $startOpts = '';
1221
1222                 $noKeyOptions = [];
1223
1224                 foreach ( $options as $key => $option ) {
1225                         if ( is_numeric( $key ) ) {
1226                                 $noKeyOptions[$option] = true;
1227                         }
1228                 }
1229
1230                 $preLimitTail .= $this->makeGroupByWithHaving( $options );
1231
1232                 $preLimitTail .= $this->makeOrderBy( $options );
1233
1234                 if ( isset( $noKeyOptions['FOR UPDATE'] ) ) {
1235                         $postLimitTail .= ' FOR UPDATE';
1236                 }
1237
1238                 if ( isset( $noKeyOptions['LOCK IN SHARE MODE'] ) ) {
1239                         $postLimitTail .= ' LOCK IN SHARE MODE';
1240                 }
1241
1242                 if ( isset( $noKeyOptions['DISTINCT'] ) || isset( $noKeyOptions['DISTINCTROW'] ) ) {
1243                         $startOpts .= 'DISTINCT';
1244                 }
1245
1246                 # Various MySQL extensions
1247                 if ( isset( $noKeyOptions['STRAIGHT_JOIN'] ) ) {
1248                         $startOpts .= ' /*! STRAIGHT_JOIN */';
1249                 }
1250
1251                 if ( isset( $noKeyOptions['HIGH_PRIORITY'] ) ) {
1252                         $startOpts .= ' HIGH_PRIORITY';
1253                 }
1254
1255                 if ( isset( $noKeyOptions['SQL_BIG_RESULT'] ) ) {
1256                         $startOpts .= ' SQL_BIG_RESULT';
1257                 }
1258
1259                 if ( isset( $noKeyOptions['SQL_BUFFER_RESULT'] ) ) {
1260                         $startOpts .= ' SQL_BUFFER_RESULT';
1261                 }
1262
1263                 if ( isset( $noKeyOptions['SQL_SMALL_RESULT'] ) ) {
1264                         $startOpts .= ' SQL_SMALL_RESULT';
1265                 }
1266
1267                 if ( isset( $noKeyOptions['SQL_CALC_FOUND_ROWS'] ) ) {
1268                         $startOpts .= ' SQL_CALC_FOUND_ROWS';
1269                 }
1270
1271                 if ( isset( $noKeyOptions['SQL_CACHE'] ) ) {
1272                         $startOpts .= ' SQL_CACHE';
1273                 }
1274
1275                 if ( isset( $noKeyOptions['SQL_NO_CACHE'] ) ) {
1276                         $startOpts .= ' SQL_NO_CACHE';
1277                 }
1278
1279                 if ( isset( $options['USE INDEX'] ) && is_string( $options['USE INDEX'] ) ) {
1280                         $useIndex = $this->useIndexClause( $options['USE INDEX'] );
1281                 } else {
1282                         $useIndex = '';
1283                 }
1284                 if ( isset( $options['IGNORE INDEX'] ) && is_string( $options['IGNORE INDEX'] ) ) {
1285                         $ignoreIndex = $this->ignoreIndexClause( $options['IGNORE INDEX'] );
1286                 } else {
1287                         $ignoreIndex = '';
1288                 }
1289
1290                 return [ $startOpts, $useIndex, $preLimitTail, $postLimitTail, $ignoreIndex ];
1291         }
1292
1293         /**
1294          * Returns an optional GROUP BY with an optional HAVING
1295          *
1296          * @param array $options Associative array of options
1297          * @return string
1298          * @see Database::select()
1299          * @since 1.21
1300          */
1301         protected function makeGroupByWithHaving( $options ) {
1302                 $sql = '';
1303                 if ( isset( $options['GROUP BY'] ) ) {
1304                         $gb = is_array( $options['GROUP BY'] )
1305                                 ? implode( ',', $options['GROUP BY'] )
1306                                 : $options['GROUP BY'];
1307                         $sql .= ' GROUP BY ' . $gb;
1308                 }
1309                 if ( isset( $options['HAVING'] ) ) {
1310                         $having = is_array( $options['HAVING'] )
1311                                 ? $this->makeList( $options['HAVING'], self::LIST_AND )
1312                                 : $options['HAVING'];
1313                         $sql .= ' HAVING ' . $having;
1314                 }
1315
1316                 return $sql;
1317         }
1318
1319         /**
1320          * Returns an optional ORDER BY
1321          *
1322          * @param array $options Associative array of options
1323          * @return string
1324          * @see Database::select()
1325          * @since 1.21
1326          */
1327         protected function makeOrderBy( $options ) {
1328                 if ( isset( $options['ORDER BY'] ) ) {
1329                         $ob = is_array( $options['ORDER BY'] )
1330                                 ? implode( ',', $options['ORDER BY'] )
1331                                 : $options['ORDER BY'];
1332
1333                         return ' ORDER BY ' . $ob;
1334                 }
1335
1336                 return '';
1337         }
1338
1339         public function select( $table, $vars, $conds = '', $fname = __METHOD__,
1340                 $options = [], $join_conds = [] ) {
1341                 $sql = $this->selectSQLText( $table, $vars, $conds, $fname, $options, $join_conds );
1342
1343                 return $this->query( $sql, $fname );
1344         }
1345
1346         public function selectSQLText( $table, $vars, $conds = '', $fname = __METHOD__,
1347                 $options = [], $join_conds = []
1348         ) {
1349                 if ( is_array( $vars ) ) {
1350                         $vars = implode( ',', $this->fieldNamesWithAlias( $vars ) );
1351                 }
1352
1353                 $options = (array)$options;
1354                 $useIndexes = ( isset( $options['USE INDEX'] ) && is_array( $options['USE INDEX'] ) )
1355                         ? $options['USE INDEX']
1356                         : [];
1357                 $ignoreIndexes = (
1358                         isset( $options['IGNORE INDEX'] ) &&
1359                         is_array( $options['IGNORE INDEX'] )
1360                 )
1361                         ? $options['IGNORE INDEX']
1362                         : [];
1363
1364                 if ( is_array( $table ) ) {
1365                         $from = ' FROM ' .
1366                                 $this->tableNamesWithIndexClauseOrJOIN(
1367                                         $table, $useIndexes, $ignoreIndexes, $join_conds );
1368                 } elseif ( $table != '' ) {
1369                         if ( $table[0] == ' ' ) {
1370                                 $from = ' FROM ' . $table;
1371                         } else {
1372                                 $from = ' FROM ' .
1373                                         $this->tableNamesWithIndexClauseOrJOIN(
1374                                                 [ $table ], $useIndexes, $ignoreIndexes, [] );
1375                         }
1376                 } else {
1377                         $from = '';
1378                 }
1379
1380                 list( $startOpts, $useIndex, $preLimitTail, $postLimitTail, $ignoreIndex ) =
1381                         $this->makeSelectOptions( $options );
1382
1383                 if ( !empty( $conds ) ) {
1384                         if ( is_array( $conds ) ) {
1385                                 $conds = $this->makeList( $conds, self::LIST_AND );
1386                         }
1387                         $sql = "SELECT $startOpts $vars $from $useIndex $ignoreIndex " .
1388                                 "WHERE $conds $preLimitTail";
1389                 } else {
1390                         $sql = "SELECT $startOpts $vars $from $useIndex $ignoreIndex $preLimitTail";
1391                 }
1392
1393                 if ( isset( $options['LIMIT'] ) ) {
1394                         $sql = $this->limitResult( $sql, $options['LIMIT'],
1395                                 isset( $options['OFFSET'] ) ? $options['OFFSET'] : false );
1396                 }
1397                 $sql = "$sql $postLimitTail";
1398
1399                 if ( isset( $options['EXPLAIN'] ) ) {
1400                         $sql = 'EXPLAIN ' . $sql;
1401                 }
1402
1403                 return $sql;
1404         }
1405
1406         public function selectRow( $table, $vars, $conds, $fname = __METHOD__,
1407                 $options = [], $join_conds = []
1408         ) {
1409                 $options = (array)$options;
1410                 $options['LIMIT'] = 1;
1411                 $res = $this->select( $table, $vars, $conds, $fname, $options, $join_conds );
1412
1413                 if ( $res === false ) {
1414                         return false;
1415                 }
1416
1417                 if ( !$this->numRows( $res ) ) {
1418                         return false;
1419                 }
1420
1421                 $obj = $this->fetchObject( $res );
1422
1423                 return $obj;
1424         }
1425
1426         public function estimateRowCount(
1427                 $table, $vars = '*', $conds = '', $fname = __METHOD__, $options = []
1428         ) {
1429                 $rows = 0;
1430                 $res = $this->select( $table, [ 'rowcount' => 'COUNT(*)' ], $conds, $fname, $options );
1431
1432                 if ( $res ) {
1433                         $row = $this->fetchRow( $res );
1434                         $rows = ( isset( $row['rowcount'] ) ) ? (int)$row['rowcount'] : 0;
1435                 }
1436
1437                 return $rows;
1438         }
1439
1440         public function selectRowCount(
1441                 $tables, $vars = '*', $conds = '', $fname = __METHOD__, $options = [], $join_conds = []
1442         ) {
1443                 $rows = 0;
1444                 $sql = $this->selectSQLText( $tables, '1', $conds, $fname, $options, $join_conds );
1445                 // The identifier quotes is primarily for MSSQL.
1446                 $rowCountCol = $this->addIdentifierQuotes( "rowcount" );
1447                 $tableName = $this->addIdentifierQuotes( "tmp_count" );
1448                 $res = $this->query( "SELECT COUNT(*) AS $rowCountCol FROM ($sql) $tableName", $fname );
1449
1450                 if ( $res ) {
1451                         $row = $this->fetchRow( $res );
1452                         $rows = ( isset( $row['rowcount'] ) ) ? (int)$row['rowcount'] : 0;
1453                 }
1454
1455                 return $rows;
1456         }
1457
1458         /**
1459          * Removes most variables from an SQL query and replaces them with X or N for numbers.
1460          * It's only slightly flawed. Don't use for anything important.
1461          *
1462          * @param string $sql A SQL Query
1463          *
1464          * @return string
1465          */
1466         protected static function generalizeSQL( $sql ) {
1467                 # This does the same as the regexp below would do, but in such a way
1468                 # as to avoid crashing php on some large strings.
1469                 # $sql = preg_replace( "/'([^\\\\']|\\\\.)*'|\"([^\\\\\"]|\\\\.)*\"/", "'X'", $sql );
1470
1471                 $sql = str_replace( "\\\\", '', $sql );
1472                 $sql = str_replace( "\\'", '', $sql );
1473                 $sql = str_replace( "\\\"", '', $sql );
1474                 $sql = preg_replace( "/'.*'/s", "'X'", $sql );
1475                 $sql = preg_replace( '/".*"/s', "'X'", $sql );
1476
1477                 # All newlines, tabs, etc replaced by single space
1478                 $sql = preg_replace( '/\s+/', ' ', $sql );
1479
1480                 # All numbers => N,
1481                 # except the ones surrounded by characters, e.g. l10n
1482                 $sql = preg_replace( '/-?\d+(,-?\d+)+/s', 'N,...,N', $sql );
1483                 $sql = preg_replace( '/(?<![a-zA-Z])-?\d+(?![a-zA-Z])/s', 'N', $sql );
1484
1485                 return $sql;
1486         }
1487
1488         public function fieldExists( $table, $field, $fname = __METHOD__ ) {
1489                 $info = $this->fieldInfo( $table, $field );
1490
1491                 return (bool)$info;
1492         }
1493
1494         public function indexExists( $table, $index, $fname = __METHOD__ ) {
1495                 if ( !$this->tableExists( $table ) ) {
1496                         return null;
1497                 }
1498
1499                 $info = $this->indexInfo( $table, $index, $fname );
1500                 if ( is_null( $info ) ) {
1501                         return null;
1502                 } else {
1503                         return $info !== false;
1504                 }
1505         }
1506
1507         public function tableExists( $table, $fname = __METHOD__ ) {
1508                 $tableRaw = $this->tableName( $table, 'raw' );
1509                 if ( isset( $this->mSessionTempTables[$tableRaw] ) ) {
1510                         return true; // already known to exist
1511                 }
1512
1513                 $table = $this->tableName( $table );
1514                 $ignoreErrors = true;
1515                 $res = $this->query( "SELECT 1 FROM $table LIMIT 1", $fname, $ignoreErrors );
1516
1517                 return (bool)$res;
1518         }
1519
1520         public function indexUnique( $table, $index ) {
1521                 $indexInfo = $this->indexInfo( $table, $index );
1522
1523                 if ( !$indexInfo ) {
1524                         return null;
1525                 }
1526
1527                 return !$indexInfo[0]->Non_unique;
1528         }
1529
1530         /**
1531          * Helper for Database::insert().
1532          *
1533          * @param array $options
1534          * @return string
1535          */
1536         protected function makeInsertOptions( $options ) {
1537                 return implode( ' ', $options );
1538         }
1539
1540         public function insert( $table, $a, $fname = __METHOD__, $options = [] ) {
1541                 # No rows to insert, easy just return now
1542                 if ( !count( $a ) ) {
1543                         return true;
1544                 }
1545
1546                 $table = $this->tableName( $table );
1547
1548                 if ( !is_array( $options ) ) {
1549                         $options = [ $options ];
1550                 }
1551
1552                 $fh = null;
1553                 if ( isset( $options['fileHandle'] ) ) {
1554                         $fh = $options['fileHandle'];
1555                 }
1556                 $options = $this->makeInsertOptions( $options );
1557
1558                 if ( isset( $a[0] ) && is_array( $a[0] ) ) {
1559                         $multi = true;
1560                         $keys = array_keys( $a[0] );
1561                 } else {
1562                         $multi = false;
1563                         $keys = array_keys( $a );
1564                 }
1565
1566                 $sql = 'INSERT ' . $options .
1567                         " INTO $table (" . implode( ',', $keys ) . ') VALUES ';
1568
1569                 if ( $multi ) {
1570                         $first = true;
1571                         foreach ( $a as $row ) {
1572                                 if ( $first ) {
1573                                         $first = false;
1574                                 } else {
1575                                         $sql .= ',';
1576                                 }
1577                                 $sql .= '(' . $this->makeList( $row ) . ')';
1578                         }
1579                 } else {
1580                         $sql .= '(' . $this->makeList( $a ) . ')';
1581                 }
1582
1583                 if ( $fh !== null && false === fwrite( $fh, $sql ) ) {
1584                         return false;
1585                 } elseif ( $fh !== null ) {
1586                         return true;
1587                 }
1588
1589                 return (bool)$this->query( $sql, $fname );
1590         }
1591
1592         /**
1593          * Make UPDATE options array for Database::makeUpdateOptions
1594          *
1595          * @param array $options
1596          * @return array
1597          */
1598         protected function makeUpdateOptionsArray( $options ) {
1599                 if ( !is_array( $options ) ) {
1600                         $options = [ $options ];
1601                 }
1602
1603                 $opts = [];
1604
1605                 if ( in_array( 'IGNORE', $options ) ) {
1606                         $opts[] = 'IGNORE';
1607                 }
1608
1609                 return $opts;
1610         }
1611
1612         /**
1613          * Make UPDATE options for the Database::update function
1614          *
1615          * @param array $options The options passed to Database::update
1616          * @return string
1617          */
1618         protected function makeUpdateOptions( $options ) {
1619                 $opts = $this->makeUpdateOptionsArray( $options );
1620
1621                 return implode( ' ', $opts );
1622         }
1623
1624         public function update( $table, $values, $conds, $fname = __METHOD__, $options = [] ) {
1625                 $table = $this->tableName( $table );
1626                 $opts = $this->makeUpdateOptions( $options );
1627                 $sql = "UPDATE $opts $table SET " . $this->makeList( $values, self::LIST_SET );
1628
1629                 if ( $conds !== [] && $conds !== '*' ) {
1630                         $sql .= " WHERE " . $this->makeList( $conds, self::LIST_AND );
1631                 }
1632
1633                 return (bool)$this->query( $sql, $fname );
1634         }
1635
1636         public function makeList( $a, $mode = self::LIST_COMMA ) {
1637                 if ( !is_array( $a ) ) {
1638                         throw new DBUnexpectedError( $this, __METHOD__ . ' called with incorrect parameters' );
1639                 }
1640
1641                 $first = true;
1642                 $list = '';
1643
1644                 foreach ( $a as $field => $value ) {
1645                         if ( !$first ) {
1646                                 if ( $mode == self::LIST_AND ) {
1647                                         $list .= ' AND ';
1648                                 } elseif ( $mode == self::LIST_OR ) {
1649                                         $list .= ' OR ';
1650                                 } else {
1651                                         $list .= ',';
1652                                 }
1653                         } else {
1654                                 $first = false;
1655                         }
1656
1657                         if ( ( $mode == self::LIST_AND || $mode == self::LIST_OR ) && is_numeric( $field ) ) {
1658                                 $list .= "($value)";
1659                         } elseif ( $mode == self::LIST_SET && is_numeric( $field ) ) {
1660                                 $list .= "$value";
1661                         } elseif (
1662                                 ( $mode == self::LIST_AND || $mode == self::LIST_OR ) && is_array( $value )
1663                         ) {
1664                                 // Remove null from array to be handled separately if found
1665                                 $includeNull = false;
1666                                 foreach ( array_keys( $value, null, true ) as $nullKey ) {
1667                                         $includeNull = true;
1668                                         unset( $value[$nullKey] );
1669                                 }
1670                                 if ( count( $value ) == 0 && !$includeNull ) {
1671                                         throw new InvalidArgumentException(
1672                                                 __METHOD__ . ": empty input for field $field" );
1673                                 } elseif ( count( $value ) == 0 ) {
1674                                         // only check if $field is null
1675                                         $list .= "$field IS NULL";
1676                                 } else {
1677                                         // IN clause contains at least one valid element
1678                                         if ( $includeNull ) {
1679                                                 // Group subconditions to ensure correct precedence
1680                                                 $list .= '(';
1681                                         }
1682                                         if ( count( $value ) == 1 ) {
1683                                                 // Special-case single values, as IN isn't terribly efficient
1684                                                 // Don't necessarily assume the single key is 0; we don't
1685                                                 // enforce linear numeric ordering on other arrays here.
1686                                                 $value = array_values( $value )[0];
1687                                                 $list .= $field . " = " . $this->addQuotes( $value );
1688                                         } else {
1689                                                 $list .= $field . " IN (" . $this->makeList( $value ) . ") ";
1690                                         }
1691                                         // if null present in array, append IS NULL
1692                                         if ( $includeNull ) {
1693                                                 $list .= " OR $field IS NULL)";
1694                                         }
1695                                 }
1696                         } elseif ( $value === null ) {
1697                                 if ( $mode == self::LIST_AND || $mode == self::LIST_OR ) {
1698                                         $list .= "$field IS ";
1699                                 } elseif ( $mode == self::LIST_SET ) {
1700                                         $list .= "$field = ";
1701                                 }
1702                                 $list .= 'NULL';
1703                         } else {
1704                                 if (
1705                                         $mode == self::LIST_AND || $mode == self::LIST_OR || $mode == self::LIST_SET
1706                                 ) {
1707                                         $list .= "$field = ";
1708                                 }
1709                                 $list .= $mode == self::LIST_NAMES ? $value : $this->addQuotes( $value );
1710                         }
1711                 }
1712
1713                 return $list;
1714         }
1715
1716         public function makeWhereFrom2d( $data, $baseKey, $subKey ) {
1717                 $conds = [];
1718
1719                 foreach ( $data as $base => $sub ) {
1720                         if ( count( $sub ) ) {
1721                                 $conds[] = $this->makeList(
1722                                         [ $baseKey => $base, $subKey => array_keys( $sub ) ],
1723                                         self::LIST_AND );
1724                         }
1725                 }
1726
1727                 if ( $conds ) {
1728                         return $this->makeList( $conds, self::LIST_OR );
1729                 } else {
1730                         // Nothing to search for...
1731                         return false;
1732                 }
1733         }
1734
1735         public function aggregateValue( $valuedata, $valuename = 'value' ) {
1736                 return $valuename;
1737         }
1738
1739         public function bitNot( $field ) {
1740                 return "(~$field)";
1741         }
1742
1743         public function bitAnd( $fieldLeft, $fieldRight ) {
1744                 return "($fieldLeft & $fieldRight)";
1745         }
1746
1747         public function bitOr( $fieldLeft, $fieldRight ) {
1748                 return "($fieldLeft | $fieldRight)";
1749         }
1750
1751         public function buildConcat( $stringList ) {
1752                 return 'CONCAT(' . implode( ',', $stringList ) . ')';
1753         }
1754
1755         public function buildGroupConcatField(
1756                 $delim, $table, $field, $conds = '', $join_conds = []
1757         ) {
1758                 $fld = "GROUP_CONCAT($field SEPARATOR " . $this->addQuotes( $delim ) . ')';
1759
1760                 return '(' . $this->selectSQLText( $table, $fld, $conds, null, [], $join_conds ) . ')';
1761         }
1762
1763         public function buildStringCast( $field ) {
1764                 return $field;
1765         }
1766
1767         public function databasesAreIndependent() {
1768                 return false;
1769         }
1770
1771         public function selectDB( $db ) {
1772                 # Stub. Shouldn't cause serious problems if it's not overridden, but
1773                 # if your database engine supports a concept similar to MySQL's
1774                 # databases you may as well.
1775                 $this->mDBname = $db;
1776
1777                 return true;
1778         }
1779
1780         public function getDBname() {
1781                 return $this->mDBname;
1782         }
1783
1784         public function getServer() {
1785                 return $this->mServer;
1786         }
1787
1788         public function tableName( $name, $format = 'quoted' ) {
1789                 # Skip the entire process when we have a string quoted on both ends.
1790                 # Note that we check the end so that we will still quote any use of
1791                 # use of `database`.table. But won't break things if someone wants
1792                 # to query a database table with a dot in the name.
1793                 if ( $this->isQuotedIdentifier( $name ) ) {
1794                         return $name;
1795                 }
1796
1797                 # Lets test for any bits of text that should never show up in a table
1798                 # name. Basically anything like JOIN or ON which are actually part of
1799                 # SQL queries, but may end up inside of the table value to combine
1800                 # sql. Such as how the API is doing.
1801                 # Note that we use a whitespace test rather than a \b test to avoid
1802                 # any remote case where a word like on may be inside of a table name
1803                 # surrounded by symbols which may be considered word breaks.
1804                 if ( preg_match( '/(^|\s)(DISTINCT|JOIN|ON|AS)(\s|$)/i', $name ) !== 0 ) {
1805                         return $name;
1806                 }
1807
1808                 # Split database and table into proper variables.
1809                 list( $database, $schema, $prefix, $table ) = $this->qualifiedTableComponents( $name );
1810
1811                 # Quote $table and apply the prefix if not quoted.
1812                 # $tableName might be empty if this is called from Database::replaceVars()
1813                 $tableName = "{$prefix}{$table}";
1814                 if ( $format === 'quoted'
1815                         && !$this->isQuotedIdentifier( $tableName )
1816                         && $tableName !== ''
1817                 ) {
1818                         $tableName = $this->addIdentifierQuotes( $tableName );
1819                 }
1820
1821                 # Quote $schema and $database and merge them with the table name if needed
1822                 $tableName = $this->prependDatabaseOrSchema( $schema, $tableName, $format );
1823                 $tableName = $this->prependDatabaseOrSchema( $database, $tableName, $format );
1824
1825                 return $tableName;
1826         }
1827
1828         /**
1829          * Get the table components needed for a query given the currently selected database
1830          *
1831          * @param string $name Table name in the form of db.schema.table, db.table, or table
1832          * @return array (DB name or "" for default, schema name, table prefix, table name)
1833          */
1834         protected function qualifiedTableComponents( $name ) {
1835                 # We reverse the explode so that database.table and table both output the correct table.
1836                 $dbDetails = explode( '.', $name, 3 );
1837                 if ( count( $dbDetails ) == 3 ) {
1838                         list( $database, $schema, $table ) = $dbDetails;
1839                         # We don't want any prefix added in this case
1840                         $prefix = '';
1841                 } elseif ( count( $dbDetails ) == 2 ) {
1842                         list( $database, $table ) = $dbDetails;
1843                         # We don't want any prefix added in this case
1844                         $prefix = '';
1845                         # In dbs that support it, $database may actually be the schema
1846                         # but that doesn't affect any of the functionality here
1847                         $schema = '';
1848                 } else {
1849                         list( $table ) = $dbDetails;
1850                         if ( isset( $this->tableAliases[$table] ) ) {
1851                                 $database = $this->tableAliases[$table]['dbname'];
1852                                 $schema = is_string( $this->tableAliases[$table]['schema'] )
1853                                         ? $this->tableAliases[$table]['schema']
1854                                         : $this->mSchema;
1855                                 $prefix = is_string( $this->tableAliases[$table]['prefix'] )
1856                                         ? $this->tableAliases[$table]['prefix']
1857                                         : $this->mTablePrefix;
1858                         } else {
1859                                 $database = '';
1860                                 $schema = $this->mSchema; # Default schema
1861                                 $prefix = $this->mTablePrefix; # Default prefix
1862                         }
1863                 }
1864
1865                 return [ $database, $schema, $prefix, $table ];
1866         }
1867
1868         /**
1869          * @param string|null $namespace Database or schema
1870          * @param string $relation Name of table, view, sequence, etc...
1871          * @param string $format One of (raw, quoted)
1872          * @return string Relation name with quoted and merged $namespace as needed
1873          */
1874         private function prependDatabaseOrSchema( $namespace, $relation, $format ) {
1875                 if ( strlen( $namespace ) ) {
1876                         if ( $format === 'quoted' && !$this->isQuotedIdentifier( $namespace ) ) {
1877                                 $namespace = $this->addIdentifierQuotes( $namespace );
1878                         }
1879                         $relation = $namespace . '.' . $relation;
1880                 }
1881
1882                 return $relation;
1883         }
1884
1885         public function tableNames() {
1886                 $inArray = func_get_args();
1887                 $retVal = [];
1888
1889                 foreach ( $inArray as $name ) {
1890                         $retVal[$name] = $this->tableName( $name );
1891                 }
1892
1893                 return $retVal;
1894         }
1895
1896         public function tableNamesN() {
1897                 $inArray = func_get_args();
1898                 $retVal = [];
1899
1900                 foreach ( $inArray as $name ) {
1901                         $retVal[] = $this->tableName( $name );
1902                 }
1903
1904                 return $retVal;
1905         }
1906
1907         /**
1908          * Get an aliased table name
1909          * e.g. tableName AS newTableName
1910          *
1911          * @param string $name Table name, see tableName()
1912          * @param string|bool $alias Alias (optional)
1913          * @return string SQL name for aliased table. Will not alias a table to its own name
1914          */
1915         protected function tableNameWithAlias( $name, $alias = false ) {
1916                 if ( !$alias || $alias == $name ) {
1917                         return $this->tableName( $name );
1918                 } else {
1919                         return $this->tableName( $name ) . ' ' . $this->addIdentifierQuotes( $alias );
1920                 }
1921         }
1922
1923         /**
1924          * Gets an array of aliased table names
1925          *
1926          * @param array $tables [ [alias] => table ]
1927          * @return string[] See tableNameWithAlias()
1928          */
1929         protected function tableNamesWithAlias( $tables ) {
1930                 $retval = [];
1931                 foreach ( $tables as $alias => $table ) {
1932                         if ( is_numeric( $alias ) ) {
1933                                 $alias = $table;
1934                         }
1935                         $retval[] = $this->tableNameWithAlias( $table, $alias );
1936                 }
1937
1938                 return $retval;
1939         }
1940
1941         /**
1942          * Get an aliased field name
1943          * e.g. fieldName AS newFieldName
1944          *
1945          * @param string $name Field name
1946          * @param string|bool $alias Alias (optional)
1947          * @return string SQL name for aliased field. Will not alias a field to its own name
1948          */
1949         protected function fieldNameWithAlias( $name, $alias = false ) {
1950                 if ( !$alias || (string)$alias === (string)$name ) {
1951                         return $name;
1952                 } else {
1953                         return $name . ' AS ' . $this->addIdentifierQuotes( $alias ); // PostgreSQL needs AS
1954                 }
1955         }
1956
1957         /**
1958          * Gets an array of aliased field names
1959          *
1960          * @param array $fields [ [alias] => field ]
1961          * @return string[] See fieldNameWithAlias()
1962          */
1963         protected function fieldNamesWithAlias( $fields ) {
1964                 $retval = [];
1965                 foreach ( $fields as $alias => $field ) {
1966                         if ( is_numeric( $alias ) ) {
1967                                 $alias = $field;
1968                         }
1969                         $retval[] = $this->fieldNameWithAlias( $field, $alias );
1970                 }
1971
1972                 return $retval;
1973         }
1974
1975         /**
1976          * Get the aliased table name clause for a FROM clause
1977          * which might have a JOIN and/or USE INDEX or IGNORE INDEX clause
1978          *
1979          * @param array $tables ( [alias] => table )
1980          * @param array $use_index Same as for select()
1981          * @param array $ignore_index Same as for select()
1982          * @param array $join_conds Same as for select()
1983          * @return string
1984          */
1985         protected function tableNamesWithIndexClauseOrJOIN(
1986                 $tables, $use_index = [], $ignore_index = [], $join_conds = []
1987         ) {
1988                 $ret = [];
1989                 $retJOIN = [];
1990                 $use_index = (array)$use_index;
1991                 $ignore_index = (array)$ignore_index;
1992                 $join_conds = (array)$join_conds;
1993
1994                 foreach ( $tables as $alias => $table ) {
1995                         if ( !is_string( $alias ) ) {
1996                                 // No alias? Set it equal to the table name
1997                                 $alias = $table;
1998                         }
1999                         // Is there a JOIN clause for this table?
2000                         if ( isset( $join_conds[$alias] ) ) {
2001                                 list( $joinType, $conds ) = $join_conds[$alias];
2002                                 $tableClause = $joinType;
2003                                 $tableClause .= ' ' . $this->tableNameWithAlias( $table, $alias );
2004                                 if ( isset( $use_index[$alias] ) ) { // has USE INDEX?
2005                                         $use = $this->useIndexClause( implode( ',', (array)$use_index[$alias] ) );
2006                                         if ( $use != '' ) {
2007                                                 $tableClause .= ' ' . $use;
2008                                         }
2009                                 }
2010                                 if ( isset( $ignore_index[$alias] ) ) { // has IGNORE INDEX?
2011                                         $ignore = $this->ignoreIndexClause(
2012                                                 implode( ',', (array)$ignore_index[$alias] ) );
2013                                         if ( $ignore != '' ) {
2014                                                 $tableClause .= ' ' . $ignore;
2015                                         }
2016                                 }
2017                                 $on = $this->makeList( (array)$conds, self::LIST_AND );
2018                                 if ( $on != '' ) {
2019                                         $tableClause .= ' ON (' . $on . ')';
2020                                 }
2021
2022                                 $retJOIN[] = $tableClause;
2023                         } elseif ( isset( $use_index[$alias] ) ) {
2024                                 // Is there an INDEX clause for this table?
2025                                 $tableClause = $this->tableNameWithAlias( $table, $alias );
2026                                 $tableClause .= ' ' . $this->useIndexClause(
2027                                                 implode( ',', (array)$use_index[$alias] )
2028                                         );
2029
2030                                 $ret[] = $tableClause;
2031                         } elseif ( isset( $ignore_index[$alias] ) ) {
2032                                 // Is there an INDEX clause for this table?
2033                                 $tableClause = $this->tableNameWithAlias( $table, $alias );
2034                                 $tableClause .= ' ' . $this->ignoreIndexClause(
2035                                                 implode( ',', (array)$ignore_index[$alias] )
2036                                         );
2037
2038                                 $ret[] = $tableClause;
2039                         } else {
2040                                 $tableClause = $this->tableNameWithAlias( $table, $alias );
2041
2042                                 $ret[] = $tableClause;
2043                         }
2044                 }
2045
2046                 // We can't separate explicit JOIN clauses with ',', use ' ' for those
2047                 $implicitJoins = !empty( $ret ) ? implode( ',', $ret ) : "";
2048                 $explicitJoins = !empty( $retJOIN ) ? implode( ' ', $retJOIN ) : "";
2049
2050                 // Compile our final table clause
2051                 return implode( ' ', [ $implicitJoins, $explicitJoins ] );
2052         }
2053
2054         /**
2055          * Allows for index remapping in queries where this is not consistent across DBMS
2056          *
2057          * @param string $index
2058          * @return string
2059          */
2060         protected function indexName( $index ) {
2061                 return $index;
2062         }
2063
2064         public function addQuotes( $s ) {
2065                 if ( $s instanceof Blob ) {
2066                         $s = $s->fetch();
2067                 }
2068                 if ( $s === null ) {
2069                         return 'NULL';
2070                 } elseif ( is_bool( $s ) ) {
2071                         return (int)$s;
2072                 } else {
2073                         # This will also quote numeric values. This should be harmless,
2074                         # and protects against weird problems that occur when they really
2075                         # _are_ strings such as article titles and string->number->string
2076                         # conversion is not 1:1.
2077                         return "'" . $this->strencode( $s ) . "'";
2078                 }
2079         }
2080
2081         /**
2082          * Quotes an identifier using `backticks` or "double quotes" depending on the database type.
2083          * MySQL uses `backticks` while basically everything else uses double quotes.
2084          * Since MySQL is the odd one out here the double quotes are our generic
2085          * and we implement backticks in DatabaseMysqlBase.
2086          *
2087          * @param string $s
2088          * @return string
2089          */
2090         public function addIdentifierQuotes( $s ) {
2091                 return '"' . str_replace( '"', '""', $s ) . '"';
2092         }
2093
2094         /**
2095          * Returns if the given identifier looks quoted or not according to
2096          * the database convention for quoting identifiers .
2097          *
2098          * @note Do not use this to determine if untrusted input is safe.
2099          *   A malicious user can trick this function.
2100          * @param string $name
2101          * @return bool
2102          */
2103         public function isQuotedIdentifier( $name ) {
2104                 return $name[0] == '"' && substr( $name, -1, 1 ) == '"';
2105         }
2106
2107         /**
2108          * @param string $s
2109          * @param string $escapeChar
2110          * @return string
2111          */
2112         protected function escapeLikeInternal( $s, $escapeChar = '`' ) {
2113                 return str_replace( [ $escapeChar, '%', '_' ],
2114                         [ "{$escapeChar}{$escapeChar}", "{$escapeChar}%", "{$escapeChar}_" ],
2115                         $s );
2116         }
2117
2118         public function buildLike() {
2119                 $params = func_get_args();
2120
2121                 if ( count( $params ) > 0 && is_array( $params[0] ) ) {
2122                         $params = $params[0];
2123                 }
2124
2125                 $s = '';
2126
2127                 // We use ` instead of \ as the default LIKE escape character, since addQuotes()
2128                 // may escape backslashes, creating problems of double escaping. The `
2129                 // character has good cross-DBMS compatibility, avoiding special operators
2130                 // in MS SQL like ^ and %
2131                 $escapeChar = '`';
2132
2133                 foreach ( $params as $value ) {
2134                         if ( $value instanceof LikeMatch ) {
2135                                 $s .= $value->toString();
2136                         } else {
2137                                 $s .= $this->escapeLikeInternal( $value, $escapeChar );
2138                         }
2139                 }
2140
2141                 return ' LIKE ' . $this->addQuotes( $s ) . ' ESCAPE ' . $this->addQuotes( $escapeChar ) . ' ';
2142         }
2143
2144         public function anyChar() {
2145                 return new LikeMatch( '_' );
2146         }
2147
2148         public function anyString() {
2149                 return new LikeMatch( '%' );
2150         }
2151
2152         public function nextSequenceValue( $seqName ) {
2153                 return null;
2154         }
2155
2156         /**
2157          * USE INDEX clause. Unlikely to be useful for anything but MySQL. This
2158          * is only needed because a) MySQL must be as efficient as possible due to
2159          * its use on Wikipedia, and b) MySQL 4.0 is kind of dumb sometimes about
2160          * which index to pick. Anyway, other databases might have different
2161          * indexes on a given table. So don't bother overriding this unless you're
2162          * MySQL.
2163          * @param string $index
2164          * @return string
2165          */
2166         public function useIndexClause( $index ) {
2167                 return '';
2168         }
2169
2170         /**
2171          * IGNORE INDEX clause. Unlikely to be useful for anything but MySQL. This
2172          * is only needed because a) MySQL must be as efficient as possible due to
2173          * its use on Wikipedia, and b) MySQL 4.0 is kind of dumb sometimes about
2174          * which index to pick. Anyway, other databases might have different
2175          * indexes on a given table. So don't bother overriding this unless you're
2176          * MySQL.
2177          * @param string $index
2178          * @return string
2179          */
2180         public function ignoreIndexClause( $index ) {
2181                 return '';
2182         }
2183
2184         public function replace( $table, $uniqueIndexes, $rows, $fname = __METHOD__ ) {
2185                 $quotedTable = $this->tableName( $table );
2186
2187                 if ( count( $rows ) == 0 ) {
2188                         return;
2189                 }
2190
2191                 # Single row case
2192                 if ( !is_array( reset( $rows ) ) ) {
2193                         $rows = [ $rows ];
2194                 }
2195
2196                 // @FXIME: this is not atomic, but a trx would break affectedRows()
2197                 foreach ( $rows as $row ) {
2198                         # Delete rows which collide
2199                         if ( $uniqueIndexes ) {
2200                                 $sql = "DELETE FROM $quotedTable WHERE ";
2201                                 $first = true;
2202                                 foreach ( $uniqueIndexes as $index ) {
2203                                         if ( $first ) {
2204                                                 $first = false;
2205                                                 $sql .= '( ';
2206                                         } else {
2207                                                 $sql .= ' ) OR ( ';
2208                                         }
2209                                         if ( is_array( $index ) ) {
2210                                                 $first2 = true;
2211                                                 foreach ( $index as $col ) {
2212                                                         if ( $first2 ) {
2213                                                                 $first2 = false;
2214                                                         } else {
2215                                                                 $sql .= ' AND ';
2216                                                         }
2217                                                         $sql .= $col . '=' . $this->addQuotes( $row[$col] );
2218                                                 }
2219                                         } else {
2220                                                 $sql .= $index . '=' . $this->addQuotes( $row[$index] );
2221                                         }
2222                                 }
2223                                 $sql .= ' )';
2224                                 $this->query( $sql, $fname );
2225                         }
2226
2227                         # Now insert the row
2228                         $this->insert( $table, $row, $fname );
2229                 }
2230         }
2231
2232         /**
2233          * REPLACE query wrapper for MySQL and SQLite, which have a native REPLACE
2234          * statement.
2235          *
2236          * @param string $table Table name
2237          * @param array|string $rows Row(s) to insert
2238          * @param string $fname Caller function name
2239          *
2240          * @return ResultWrapper
2241          */
2242         protected function nativeReplace( $table, $rows, $fname ) {
2243                 $table = $this->tableName( $table );
2244
2245                 # Single row case
2246                 if ( !is_array( reset( $rows ) ) ) {
2247                         $rows = [ $rows ];
2248                 }
2249
2250                 $sql = "REPLACE INTO $table (" . implode( ',', array_keys( $rows[0] ) ) . ') VALUES ';
2251                 $first = true;
2252
2253                 foreach ( $rows as $row ) {
2254                         if ( $first ) {
2255                                 $first = false;
2256                         } else {
2257                                 $sql .= ',';
2258                         }
2259
2260                         $sql .= '(' . $this->makeList( $row ) . ')';
2261                 }
2262
2263                 return $this->query( $sql, $fname );
2264         }
2265
2266         public function upsert( $table, array $rows, array $uniqueIndexes, array $set,
2267                 $fname = __METHOD__
2268         ) {
2269                 if ( !count( $rows ) ) {
2270                         return true; // nothing to do
2271                 }
2272
2273                 if ( !is_array( reset( $rows ) ) ) {
2274                         $rows = [ $rows ];
2275                 }
2276
2277                 if ( count( $uniqueIndexes ) ) {
2278                         $clauses = []; // list WHERE clauses that each identify a single row
2279                         foreach ( $rows as $row ) {
2280                                 foreach ( $uniqueIndexes as $index ) {
2281                                         $index = is_array( $index ) ? $index : [ $index ]; // columns
2282                                         $rowKey = []; // unique key to this row
2283                                         foreach ( $index as $column ) {
2284                                                 $rowKey[$column] = $row[$column];
2285                                         }
2286                                         $clauses[] = $this->makeList( $rowKey, self::LIST_AND );
2287                                 }
2288                         }
2289                         $where = [ $this->makeList( $clauses, self::LIST_OR ) ];
2290                 } else {
2291                         $where = false;
2292                 }
2293
2294                 $useTrx = !$this->mTrxLevel;
2295                 if ( $useTrx ) {
2296                         $this->begin( $fname, self::TRANSACTION_INTERNAL );
2297                 }
2298                 try {
2299                         # Update any existing conflicting row(s)
2300                         if ( $where !== false ) {
2301                                 $ok = $this->update( $table, $set, $where, $fname );
2302                         } else {
2303                                 $ok = true;
2304                         }
2305                         # Now insert any non-conflicting row(s)
2306                         $ok = $this->insert( $table, $rows, $fname, [ 'IGNORE' ] ) && $ok;
2307                 } catch ( Exception $e ) {
2308                         if ( $useTrx ) {
2309                                 $this->rollback( $fname, self::FLUSHING_INTERNAL );
2310                         }
2311                         throw $e;
2312                 }
2313                 if ( $useTrx ) {
2314                         $this->commit( $fname, self::FLUSHING_INTERNAL );
2315                 }
2316
2317                 return $ok;
2318         }
2319
2320         public function deleteJoin( $delTable, $joinTable, $delVar, $joinVar, $conds,
2321                 $fname = __METHOD__
2322         ) {
2323                 if ( !$conds ) {
2324                         throw new DBUnexpectedError( $this, __METHOD__ . ' called with empty $conds' );
2325                 }
2326
2327                 $delTable = $this->tableName( $delTable );
2328                 $joinTable = $this->tableName( $joinTable );
2329                 $sql = "DELETE FROM $delTable WHERE $delVar IN (SELECT $joinVar FROM $joinTable ";
2330                 if ( $conds != '*' ) {
2331                         $sql .= 'WHERE ' . $this->makeList( $conds, self::LIST_AND );
2332                 }
2333                 $sql .= ')';
2334
2335                 $this->query( $sql, $fname );
2336         }
2337
2338         public function textFieldSize( $table, $field ) {
2339                 $table = $this->tableName( $table );
2340                 $sql = "SHOW COLUMNS FROM $table LIKE \"$field\";";
2341                 $res = $this->query( $sql, __METHOD__ );
2342                 $row = $this->fetchObject( $res );
2343
2344                 $m = [];
2345
2346                 if ( preg_match( '/\((.*)\)/', $row->Type, $m ) ) {
2347                         $size = $m[1];
2348                 } else {
2349                         $size = -1;
2350                 }
2351
2352                 return $size;
2353         }
2354
2355         public function delete( $table, $conds, $fname = __METHOD__ ) {
2356                 if ( !$conds ) {
2357                         throw new DBUnexpectedError( $this, __METHOD__ . ' called with no conditions' );
2358                 }
2359
2360                 $table = $this->tableName( $table );
2361                 $sql = "DELETE FROM $table";
2362
2363                 if ( $conds != '*' ) {
2364                         if ( is_array( $conds ) ) {
2365                                 $conds = $this->makeList( $conds, self::LIST_AND );
2366                         }
2367                         $sql .= ' WHERE ' . $conds;
2368                 }
2369
2370                 return $this->query( $sql, $fname );
2371         }
2372
2373         public function insertSelect(
2374                 $destTable, $srcTable, $varMap, $conds,
2375                 $fname = __METHOD__, $insertOptions = [], $selectOptions = [], $selectJoinConds = []
2376         ) {
2377                 if ( $this->cliMode ) {
2378                         // For massive migrations with downtime, we don't want to select everything
2379                         // into memory and OOM, so do all this native on the server side if possible.
2380                         return $this->nativeInsertSelect(
2381                                 $destTable,
2382                                 $srcTable,
2383                                 $varMap,
2384                                 $conds,
2385                                 $fname,
2386                                 $insertOptions,
2387                                 $selectOptions,
2388                                 $selectJoinConds
2389                         );
2390                 }
2391
2392                 // For web requests, do a locking SELECT and then INSERT. This puts the SELECT burden
2393                 // on only the master (without needing row-based-replication). It also makes it easy to
2394                 // know how big the INSERT is going to be.
2395                 $fields = [];
2396                 foreach ( $varMap as $dstColumn => $sourceColumnOrSql ) {
2397                         $fields[] = $this->fieldNameWithAlias( $sourceColumnOrSql, $dstColumn );
2398                 }
2399                 $selectOptions[] = 'FOR UPDATE';
2400                 $res = $this->select(
2401                         $srcTable, implode( ',', $fields ), $conds, $fname, $selectOptions, $selectJoinConds
2402                 );
2403                 if ( !$res ) {
2404                         return false;
2405                 }
2406
2407                 $rows = [];
2408                 foreach ( $res as $row ) {
2409                         $rows[] = (array)$row;
2410                 }
2411
2412                 return $this->insert( $destTable, $rows, $fname, $insertOptions );
2413         }
2414
2415         /**
2416          * Native server-side implementation of insertSelect() for situations where
2417          * we don't want to select everything into memory
2418          *
2419          * @see IDatabase::insertSelect()
2420          * @param string $destTable
2421          * @param string|array $srcTable
2422          * @param array $varMap
2423          * @param array $conds
2424          * @param string $fname
2425          * @param array $insertOptions
2426          * @param array $selectOptions
2427          * @param array $selectJoinConds
2428          * @return bool
2429          */
2430         protected function nativeInsertSelect( $destTable, $srcTable, $varMap, $conds,
2431                 $fname = __METHOD__,
2432                 $insertOptions = [], $selectOptions = [], $selectJoinConds = []
2433         ) {
2434                 $destTable = $this->tableName( $destTable );
2435
2436                 if ( !is_array( $insertOptions ) ) {
2437                         $insertOptions = [ $insertOptions ];
2438                 }
2439
2440                 $insertOptions = $this->makeInsertOptions( $insertOptions );
2441
2442                 $selectSql = $this->selectSQLText(
2443                         $srcTable,
2444                         array_values( $varMap ),
2445                         $conds,
2446                         $fname,
2447                         $selectOptions,
2448                         $selectJoinConds
2449                 );
2450
2451                 $sql = "INSERT $insertOptions" .
2452                         " INTO $destTable (" . implode( ',', array_keys( $varMap ) ) . ') ' .
2453                         $selectSql;
2454
2455                 return $this->query( $sql, $fname );
2456         }
2457
2458         /**
2459          * Construct a LIMIT query with optional offset. This is used for query
2460          * pages. The SQL should be adjusted so that only the first $limit rows
2461          * are returned. If $offset is provided as well, then the first $offset
2462          * rows should be discarded, and the next $limit rows should be returned.
2463          * If the result of the query is not ordered, then the rows to be returned
2464          * are theoretically arbitrary.
2465          *
2466          * $sql is expected to be a SELECT, if that makes a difference.
2467          *
2468          * The version provided by default works in MySQL and SQLite. It will very
2469          * likely need to be overridden for most other DBMSes.
2470          *
2471          * @param string $sql SQL query we will append the limit too
2472          * @param int $limit The SQL limit
2473          * @param int|bool $offset The SQL offset (default false)
2474          * @throws DBUnexpectedError
2475          * @return string
2476          */
2477         public function limitResult( $sql, $limit, $offset = false ) {
2478                 if ( !is_numeric( $limit ) ) {
2479                         throw new DBUnexpectedError( $this,
2480                                 "Invalid non-numeric limit passed to limitResult()\n" );
2481                 }
2482
2483                 return "$sql LIMIT "
2484                 . ( ( is_numeric( $offset ) && $offset != 0 ) ? "{$offset}," : "" )
2485                 . "{$limit} ";
2486         }
2487
2488         public function unionSupportsOrderAndLimit() {
2489                 return true; // True for almost every DB supported
2490         }
2491
2492         public function unionQueries( $sqls, $all ) {
2493                 $glue = $all ? ') UNION ALL (' : ') UNION (';
2494
2495                 return '(' . implode( $glue, $sqls ) . ')';
2496         }
2497
2498         public function unionConditionPermutations(
2499                 $table, $vars, array $permute_conds, $extra_conds = '', $fname = __METHOD__,
2500                 $options = [], $join_conds = []
2501         ) {
2502                 // First, build the Cartesian product of $permute_conds
2503                 $conds = [ [] ];
2504                 foreach ( $permute_conds as $field => $values ) {
2505                         if ( !$values ) {
2506                                 // Skip empty $values
2507                                 continue;
2508                         }
2509                         $values = array_unique( $values ); // For sanity
2510                         $newConds = [];
2511                         foreach ( $conds as $cond ) {
2512                                 foreach ( $values as $value ) {
2513                                         $cond[$field] = $value;
2514                                         $newConds[] = $cond; // Arrays are by-value, not by-reference, so this works
2515                                 }
2516                         }
2517                         $conds = $newConds;
2518                 }
2519
2520                 $extra_conds = $extra_conds === '' ? [] : (array)$extra_conds;
2521
2522                 // If there's just one condition and no subordering, hand off to
2523                 // selectSQLText directly.
2524                 if ( count( $conds ) === 1 &&
2525                         ( !isset( $options['INNER ORDER BY'] ) || !$this->unionSupportsOrderAndLimit() )
2526                 ) {
2527                         return $this->selectSQLText(
2528                                 $table, $vars, $conds[0] + $extra_conds, $fname, $options, $join_conds
2529                         );
2530                 }
2531
2532                 // Otherwise, we need to pull out the order and limit to apply after
2533                 // the union. Then build the SQL queries for each set of conditions in
2534                 // $conds. Then union them together (using UNION ALL, because the
2535                 // product *should* already be distinct).
2536                 $orderBy = $this->makeOrderBy( $options );
2537                 $limit = isset( $options['LIMIT'] ) ? $options['LIMIT'] : null;
2538                 $offset = isset( $options['OFFSET'] ) ? $options['OFFSET'] : false;
2539                 $all = empty( $options['NOTALL'] ) && !in_array( 'NOTALL', $options );
2540                 if ( !$this->unionSupportsOrderAndLimit() ) {
2541                         unset( $options['ORDER BY'], $options['LIMIT'], $options['OFFSET'] );
2542                 } else {
2543                         if ( array_key_exists( 'INNER ORDER BY', $options ) ) {
2544                                 $options['ORDER BY'] = $options['INNER ORDER BY'];
2545                         }
2546                         if ( $limit !== null && is_numeric( $offset ) && $offset != 0 ) {
2547                                 // We need to increase the limit by the offset rather than
2548                                 // using the offset directly, otherwise it'll skip incorrectly
2549                                 // in the subqueries.
2550                                 $options['LIMIT'] = $limit + $offset;
2551                                 unset( $options['OFFSET'] );
2552                         }
2553                 }
2554
2555                 $sqls = [];
2556                 foreach ( $conds as $cond ) {
2557                         $sqls[] = $this->selectSQLText(
2558                                 $table, $vars, $cond + $extra_conds, $fname, $options, $join_conds
2559                         );
2560                 }
2561                 $sql = $this->unionQueries( $sqls, $all ) . $orderBy;
2562                 if ( $limit !== null ) {
2563                         $sql = $this->limitResult( $sql, $limit, $offset );
2564                 }
2565
2566                 return $sql;
2567         }
2568
2569         public function conditional( $cond, $trueVal, $falseVal ) {
2570                 if ( is_array( $cond ) ) {
2571                         $cond = $this->makeList( $cond, self::LIST_AND );
2572                 }
2573
2574                 return " (CASE WHEN $cond THEN $trueVal ELSE $falseVal END) ";
2575         }
2576
2577         public function strreplace( $orig, $old, $new ) {
2578                 return "REPLACE({$orig}, {$old}, {$new})";
2579         }
2580
2581         public function getServerUptime() {
2582                 return 0;
2583         }
2584
2585         public function wasDeadlock() {
2586                 return false;
2587         }
2588
2589         public function wasLockTimeout() {
2590                 return false;
2591         }
2592
2593         public function wasErrorReissuable() {
2594                 return false;
2595         }
2596
2597         public function wasReadOnlyError() {
2598                 return false;
2599         }
2600
2601         /**
2602          * Do not use this method outside of Database/DBError classes
2603          *
2604          * @param int|string $errno
2605          * @return bool Whether the given query error was a connection drop
2606          */
2607         public function wasConnectionError( $errno ) {
2608                 return false;
2609         }
2610
2611         public function deadlockLoop() {
2612                 $args = func_get_args();
2613                 $function = array_shift( $args );
2614                 $tries = self::DEADLOCK_TRIES;
2615
2616                 $this->begin( __METHOD__ );
2617
2618                 $retVal = null;
2619                 /** @var Exception $e */
2620                 $e = null;
2621                 do {
2622                         try {
2623                                 $retVal = call_user_func_array( $function, $args );
2624                                 break;
2625                         } catch ( DBQueryError $e ) {
2626                                 if ( $this->wasDeadlock() ) {
2627                                         // Retry after a randomized delay
2628                                         usleep( mt_rand( self::DEADLOCK_DELAY_MIN, self::DEADLOCK_DELAY_MAX ) );
2629                                 } else {
2630                                         // Throw the error back up
2631                                         throw $e;
2632                                 }
2633                         }
2634                 } while ( --$tries > 0 );
2635
2636                 if ( $tries <= 0 ) {
2637                         // Too many deadlocks; give up
2638                         $this->rollback( __METHOD__ );
2639                         throw $e;
2640                 } else {
2641                         $this->commit( __METHOD__ );
2642
2643                         return $retVal;
2644                 }
2645         }
2646
2647         public function masterPosWait( DBMasterPos $pos, $timeout ) {
2648                 # Real waits are implemented in the subclass.
2649                 return 0;
2650         }
2651
2652         public function getReplicaPos() {
2653                 # Stub
2654                 return false;
2655         }
2656
2657         public function getMasterPos() {
2658                 # Stub
2659                 return false;
2660         }
2661
2662         public function serverIsReadOnly() {
2663                 return false;
2664         }
2665
2666         final public function onTransactionResolution( callable $callback, $fname = __METHOD__ ) {
2667                 if ( !$this->mTrxLevel ) {
2668                         throw new DBUnexpectedError( $this, "No transaction is active." );
2669                 }
2670                 $this->mTrxEndCallbacks[] = [ $callback, $fname ];
2671         }
2672
2673         final public function onTransactionIdle( callable $callback, $fname = __METHOD__ ) {
2674                 $this->mTrxIdleCallbacks[] = [ $callback, $fname ];
2675                 if ( !$this->mTrxLevel ) {
2676                         $this->runOnTransactionIdleCallbacks( self::TRIGGER_IDLE );
2677                 }
2678         }
2679
2680         final public function onTransactionPreCommitOrIdle( callable $callback, $fname = __METHOD__ ) {
2681                 if ( $this->mTrxLevel || $this->getFlag( self::DBO_TRX ) ) {
2682                         // As long as DBO_TRX is set, writes will accumulate until the load balancer issues
2683                         // an implicit commit of all peer databases. This is true even if a transaction has
2684                         // not yet been triggered by writes; make sure $callback runs *after* any such writes.
2685                         $this->mTrxPreCommitCallbacks[] = [ $callback, $fname ];
2686                 } else {
2687                         // No transaction is active nor will start implicitly, so make one for this callback
2688                         $this->startAtomic( __METHOD__ );
2689                         try {
2690                                 call_user_func( $callback );
2691                                 $this->endAtomic( __METHOD__ );
2692                         } catch ( Exception $e ) {
2693                                 $this->rollback( __METHOD__, self::FLUSHING_INTERNAL );
2694                                 throw $e;
2695                         }
2696                 }
2697         }
2698
2699         final public function setTransactionListener( $name, callable $callback = null ) {
2700                 if ( $callback ) {
2701                         $this->mTrxRecurringCallbacks[$name] = $callback;
2702                 } else {
2703                         unset( $this->mTrxRecurringCallbacks[$name] );
2704                 }
2705         }
2706
2707         /**
2708          * Whether to disable running of post-COMMIT/ROLLBACK callbacks
2709          *
2710          * This method should not be used outside of Database/LoadBalancer
2711          *
2712          * @param bool $suppress
2713          * @since 1.28
2714          */
2715         final public function setTrxEndCallbackSuppression( $suppress ) {
2716                 $this->mTrxEndCallbacksSuppressed = $suppress;
2717         }
2718
2719         /**
2720          * Actually run and consume any "on transaction idle/resolution" callbacks.
2721          *
2722          * This method should not be used outside of Database/LoadBalancer
2723          *
2724          * @param int $trigger IDatabase::TRIGGER_* constant
2725          * @since 1.20
2726          * @throws Exception
2727          */
2728         public function runOnTransactionIdleCallbacks( $trigger ) {
2729                 if ( $this->mTrxEndCallbacksSuppressed ) {
2730                         return;
2731                 }
2732
2733                 $autoTrx = $this->getFlag( self::DBO_TRX ); // automatic begin() enabled?
2734                 /** @var Exception $e */
2735                 $e = null; // first exception
2736                 do { // callbacks may add callbacks :)
2737                         $callbacks = array_merge(
2738                                 $this->mTrxIdleCallbacks,
2739                                 $this->mTrxEndCallbacks // include "transaction resolution" callbacks
2740                         );
2741                         $this->mTrxIdleCallbacks = []; // consumed (and recursion guard)
2742                         $this->mTrxEndCallbacks = []; // consumed (recursion guard)
2743                         foreach ( $callbacks as $callback ) {
2744                                 try {
2745                                         list( $phpCallback ) = $callback;
2746                                         $this->clearFlag( self::DBO_TRX ); // make each query its own transaction
2747                                         call_user_func_array( $phpCallback, [ $trigger ] );
2748                                         if ( $autoTrx ) {
2749                                                 $this->setFlag( self::DBO_TRX ); // restore automatic begin()
2750                                         } else {
2751                                                 $this->clearFlag( self::DBO_TRX ); // restore auto-commit
2752                                         }
2753                                 } catch ( Exception $ex ) {
2754                                         call_user_func( $this->errorLogger, $ex );
2755                                         $e = $e ?: $ex;
2756                                         // Some callbacks may use startAtomic/endAtomic, so make sure
2757                                         // their transactions are ended so other callbacks don't fail
2758                                         if ( $this->trxLevel() ) {
2759                                                 $this->rollback( __METHOD__, self::FLUSHING_INTERNAL );
2760                                         }
2761                                 }
2762                         }
2763                 } while ( count( $this->mTrxIdleCallbacks ) );
2764
2765                 if ( $e instanceof Exception ) {
2766                         throw $e; // re-throw any first exception
2767                 }
2768         }
2769
2770         /**
2771          * Actually run and consume any "on transaction pre-commit" callbacks.
2772          *
2773          * This method should not be used outside of Database/LoadBalancer
2774          *
2775          * @since 1.22
2776          * @throws Exception
2777          */
2778         public function runOnTransactionPreCommitCallbacks() {
2779                 $e = null; // first exception
2780                 do { // callbacks may add callbacks :)
2781                         $callbacks = $this->mTrxPreCommitCallbacks;
2782                         $this->mTrxPreCommitCallbacks = []; // consumed (and recursion guard)
2783                         foreach ( $callbacks as $callback ) {
2784                                 try {
2785                                         list( $phpCallback ) = $callback;
2786                                         call_user_func( $phpCallback );
2787                                 } catch ( Exception $ex ) {
2788                                         call_user_func( $this->errorLogger, $ex );
2789                                         $e = $e ?: $ex;
2790                                 }
2791                         }
2792                 } while ( count( $this->mTrxPreCommitCallbacks ) );
2793
2794                 if ( $e instanceof Exception ) {
2795                         throw $e; // re-throw any first exception
2796                 }
2797         }
2798
2799         /**
2800          * Actually run any "transaction listener" callbacks.
2801          *
2802          * This method should not be used outside of Database/LoadBalancer
2803          *
2804          * @param int $trigger IDatabase::TRIGGER_* constant
2805          * @throws Exception
2806          * @since 1.20
2807          */
2808         public function runTransactionListenerCallbacks( $trigger ) {
2809                 if ( $this->mTrxEndCallbacksSuppressed ) {
2810                         return;
2811                 }
2812
2813                 /** @var Exception $e */
2814                 $e = null; // first exception
2815
2816                 foreach ( $this->mTrxRecurringCallbacks as $phpCallback ) {
2817                         try {
2818                                 $phpCallback( $trigger, $this );
2819                         } catch ( Exception $ex ) {
2820                                 call_user_func( $this->errorLogger, $ex );
2821                                 $e = $e ?: $ex;
2822                         }
2823                 }
2824
2825                 if ( $e instanceof Exception ) {
2826                         throw $e; // re-throw any first exception
2827                 }
2828         }
2829
2830         final public function startAtomic( $fname = __METHOD__ ) {
2831                 if ( !$this->mTrxLevel ) {
2832                         $this->begin( $fname, self::TRANSACTION_INTERNAL );
2833                         // If DBO_TRX is set, a series of startAtomic/endAtomic pairs will result
2834                         // in all changes being in one transaction to keep requests transactional.
2835                         if ( !$this->getFlag( self::DBO_TRX ) ) {
2836                                 $this->mTrxAutomaticAtomic = true;
2837                         }
2838                 }
2839
2840                 $this->mTrxAtomicLevels[] = $fname;
2841         }
2842
2843         final public function endAtomic( $fname = __METHOD__ ) {
2844                 if ( !$this->mTrxLevel ) {
2845                         throw new DBUnexpectedError( $this, "No atomic transaction is open (got $fname)." );
2846                 }
2847                 if ( !$this->mTrxAtomicLevels ||
2848                         array_pop( $this->mTrxAtomicLevels ) !== $fname
2849                 ) {
2850                         throw new DBUnexpectedError( $this, "Invalid atomic section ended (got $fname)." );
2851                 }
2852
2853                 if ( !$this->mTrxAtomicLevels && $this->mTrxAutomaticAtomic ) {
2854                         $this->commit( $fname, self::FLUSHING_INTERNAL );
2855                 }
2856         }
2857
2858         final public function doAtomicSection( $fname, callable $callback ) {
2859                 $this->startAtomic( $fname );
2860                 try {
2861                         $res = call_user_func_array( $callback, [ $this, $fname ] );
2862                 } catch ( Exception $e ) {
2863                         $this->rollback( $fname, self::FLUSHING_INTERNAL );
2864                         throw $e;
2865                 }
2866                 $this->endAtomic( $fname );
2867
2868                 return $res;
2869         }
2870
2871         final public function begin( $fname = __METHOD__, $mode = self::TRANSACTION_EXPLICIT ) {
2872                 // Protect against mismatched atomic section, transaction nesting, and snapshot loss
2873                 if ( $this->mTrxLevel ) {
2874                         if ( $this->mTrxAtomicLevels ) {
2875                                 $levels = implode( ', ', $this->mTrxAtomicLevels );
2876                                 $msg = "$fname: Got explicit BEGIN while atomic section(s) $levels are open.";
2877                                 throw new DBUnexpectedError( $this, $msg );
2878                         } elseif ( !$this->mTrxAutomatic ) {
2879                                 $msg = "$fname: Explicit transaction already active (from {$this->mTrxFname}).";
2880                                 throw new DBUnexpectedError( $this, $msg );
2881                         } else {
2882                                 // @TODO: make this an exception at some point
2883                                 $msg = "$fname: Implicit transaction already active (from {$this->mTrxFname}).";
2884                                 $this->queryLogger->error( $msg );
2885                                 return; // join the main transaction set
2886                         }
2887                 } elseif ( $this->getFlag( self::DBO_TRX ) && $mode !== self::TRANSACTION_INTERNAL ) {
2888                         // @TODO: make this an exception at some point
2889                         $msg = "$fname: Implicit transaction expected (DBO_TRX set).";
2890                         $this->queryLogger->error( $msg );
2891                         return; // let any writes be in the main transaction
2892                 }
2893
2894                 // Avoid fatals if close() was called
2895                 $this->assertOpen();
2896
2897                 $this->doBegin( $fname );
2898                 $this->mTrxTimestamp = microtime( true );
2899                 $this->mTrxFname = $fname;
2900                 $this->mTrxDoneWrites = false;
2901                 $this->mTrxAutomaticAtomic = false;
2902                 $this->mTrxAtomicLevels = [];
2903                 $this->mTrxShortId = sprintf( '%06x', mt_rand( 0, 0xffffff ) );
2904                 $this->mTrxWriteDuration = 0.0;
2905                 $this->mTrxWriteQueryCount = 0;
2906                 $this->mTrxWriteAffectedRows = 0;
2907                 $this->mTrxWriteAdjDuration = 0.0;
2908                 $this->mTrxWriteAdjQueryCount = 0;
2909                 $this->mTrxWriteCallers = [];
2910                 // First SELECT after BEGIN will establish the snapshot in REPEATABLE-READ.
2911                 // Get an estimate of the replica DB lag before then, treating estimate staleness
2912                 // as lag itself just to be safe
2913                 $status = $this->getApproximateLagStatus();
2914                 $this->mTrxReplicaLag = $status['lag'] + ( microtime( true ) - $status['since'] );
2915                 // T147697: make explicitTrxActive() return true until begin() finishes. This way, no
2916                 // caller will think its OK to muck around with the transaction just because startAtomic()
2917                 // has not yet completed (e.g. setting mTrxAtomicLevels).
2918                 $this->mTrxAutomatic = ( $mode === self::TRANSACTION_INTERNAL );
2919         }
2920
2921         /**
2922          * Issues the BEGIN command to the database server.
2923          *
2924          * @see Database::begin()
2925          * @param string $fname
2926          */
2927         protected function doBegin( $fname ) {
2928                 $this->query( 'BEGIN', $fname );
2929                 $this->mTrxLevel = 1;
2930         }
2931
2932         final public function commit( $fname = __METHOD__, $flush = '' ) {
2933                 if ( $this->mTrxLevel && $this->mTrxAtomicLevels ) {
2934                         // There are still atomic sections open. This cannot be ignored
2935                         $levels = implode( ', ', $this->mTrxAtomicLevels );
2936                         throw new DBUnexpectedError(
2937                                 $this,
2938                                 "$fname: Got COMMIT while atomic sections $levels are still open."
2939                         );
2940                 }
2941
2942                 if ( $flush === self::FLUSHING_INTERNAL || $flush === self::FLUSHING_ALL_PEERS ) {
2943                         if ( !$this->mTrxLevel ) {
2944                                 return; // nothing to do
2945                         } elseif ( !$this->mTrxAutomatic ) {
2946                                 throw new DBUnexpectedError(
2947                                         $this,
2948                                         "$fname: Flushing an explicit transaction, getting out of sync."
2949                                 );
2950                         }
2951                 } else {
2952                         if ( !$this->mTrxLevel ) {
2953                                 $this->queryLogger->error(
2954                                         "$fname: No transaction to commit, something got out of sync." );
2955                                 return; // nothing to do
2956                         } elseif ( $this->mTrxAutomatic ) {
2957                                 // @TODO: make this an exception at some point
2958                                 $msg = "$fname: Explicit commit of implicit transaction.";
2959                                 $this->queryLogger->error( $msg );
2960                                 return; // wait for the main transaction set commit round
2961                         }
2962                 }
2963
2964                 // Avoid fatals if close() was called
2965                 $this->assertOpen();
2966
2967                 $this->runOnTransactionPreCommitCallbacks();
2968                 $writeTime = $this->pendingWriteQueryDuration( self::ESTIMATE_DB_APPLY );
2969                 $this->doCommit( $fname );
2970                 if ( $this->mTrxDoneWrites ) {
2971                         $this->mLastWriteTime = microtime( true );
2972                         $this->trxProfiler->transactionWritingOut(
2973                                 $this->mServer,
2974                                 $this->mDBname,
2975                                 $this->mTrxShortId,
2976                                 $writeTime,
2977                                 $this->mTrxWriteAffectedRows
2978                         );
2979                 }
2980
2981                 $this->runOnTransactionIdleCallbacks( self::TRIGGER_COMMIT );
2982                 $this->runTransactionListenerCallbacks( self::TRIGGER_COMMIT );
2983         }
2984
2985         /**
2986          * Issues the COMMIT command to the database server.
2987          *
2988          * @see Database::commit()
2989          * @param string $fname
2990          */
2991         protected function doCommit( $fname ) {
2992                 if ( $this->mTrxLevel ) {
2993                         $this->query( 'COMMIT', $fname );
2994                         $this->mTrxLevel = 0;
2995                 }
2996         }
2997
2998         final public function rollback( $fname = __METHOD__, $flush = '' ) {
2999                 if ( $flush === self::FLUSHING_INTERNAL || $flush === self::FLUSHING_ALL_PEERS ) {
3000                         if ( !$this->mTrxLevel ) {
3001                                 return; // nothing to do
3002                         }
3003                 } else {
3004                         if ( !$this->mTrxLevel ) {
3005                                 $this->queryLogger->error(
3006                                         "$fname: No transaction to rollback, something got out of sync." );
3007                                 return; // nothing to do
3008                         } elseif ( $this->getFlag( self::DBO_TRX ) ) {
3009                                 throw new DBUnexpectedError(
3010                                         $this,
3011                                         "$fname: Expected mass rollback of all peer databases (DBO_TRX set)."
3012                                 );
3013                         }
3014                 }
3015
3016                 // Avoid fatals if close() was called
3017                 $this->assertOpen();
3018
3019                 $this->doRollback( $fname );
3020                 $this->mTrxAtomicLevels = [];
3021                 if ( $this->mTrxDoneWrites ) {
3022                         $this->trxProfiler->transactionWritingOut(
3023                                 $this->mServer,
3024                                 $this->mDBname,
3025                                 $this->mTrxShortId
3026                         );
3027                 }
3028
3029                 $this->mTrxIdleCallbacks = []; // clear
3030                 $this->mTrxPreCommitCallbacks = []; // clear
3031                 $this->runOnTransactionIdleCallbacks( self::TRIGGER_ROLLBACK );
3032                 $this->runTransactionListenerCallbacks( self::TRIGGER_ROLLBACK );
3033         }
3034
3035         /**
3036          * Issues the ROLLBACK command to the database server.
3037          *
3038          * @see Database::rollback()
3039          * @param string $fname
3040          */
3041         protected function doRollback( $fname ) {
3042                 if ( $this->mTrxLevel ) {
3043                         # Disconnects cause rollback anyway, so ignore those errors
3044                         $ignoreErrors = true;
3045                         $this->query( 'ROLLBACK', $fname, $ignoreErrors );
3046                         $this->mTrxLevel = 0;
3047                 }
3048         }
3049
3050         public function flushSnapshot( $fname = __METHOD__ ) {
3051                 if ( $this->writesOrCallbacksPending() || $this->explicitTrxActive() ) {
3052                         // This only flushes transactions to clear snapshots, not to write data
3053                         $fnames = implode( ', ', $this->pendingWriteAndCallbackCallers() );
3054                         throw new DBUnexpectedError(
3055                                 $this,
3056                                 "$fname: Cannot flush snapshot because writes are pending ($fnames)."
3057                         );
3058                 }
3059
3060                 $this->commit( $fname, self::FLUSHING_INTERNAL );
3061         }
3062
3063         public function explicitTrxActive() {
3064                 return $this->mTrxLevel && ( $this->mTrxAtomicLevels || !$this->mTrxAutomatic );
3065         }
3066
3067         public function duplicateTableStructure(
3068                 $oldName, $newName, $temporary = false, $fname = __METHOD__
3069         ) {
3070                 throw new RuntimeException( __METHOD__ . ' is not implemented in descendant class' );
3071         }
3072
3073         public function listTables( $prefix = null, $fname = __METHOD__ ) {
3074                 throw new RuntimeException( __METHOD__ . ' is not implemented in descendant class' );
3075         }
3076
3077         public function listViews( $prefix = null, $fname = __METHOD__ ) {
3078                 throw new RuntimeException( __METHOD__ . ' is not implemented in descendant class' );
3079         }
3080
3081         public function timestamp( $ts = 0 ) {
3082                 $t = new ConvertibleTimestamp( $ts );
3083                 // Let errors bubble up to avoid putting garbage in the DB
3084                 return $t->getTimestamp( TS_MW );
3085         }
3086
3087         public function timestampOrNull( $ts = null ) {
3088                 if ( is_null( $ts ) ) {
3089                         return null;
3090                 } else {
3091                         return $this->timestamp( $ts );
3092                 }
3093         }
3094
3095         /**
3096          * Take the result from a query, and wrap it in a ResultWrapper if
3097          * necessary. Boolean values are passed through as is, to indicate success
3098          * of write queries or failure.
3099          *
3100          * Once upon a time, Database::query() returned a bare MySQL result
3101          * resource, and it was necessary to call this function to convert it to
3102          * a wrapper. Nowadays, raw database objects are never exposed to external
3103          * callers, so this is unnecessary in external code.
3104          *
3105          * @param bool|ResultWrapper|resource|object $result
3106          * @return bool|ResultWrapper
3107          */
3108         protected function resultObject( $result ) {
3109                 if ( !$result ) {
3110                         return false;
3111                 } elseif ( $result instanceof ResultWrapper ) {
3112                         return $result;
3113                 } elseif ( $result === true ) {
3114                         // Successful write query
3115                         return $result;
3116                 } else {
3117                         return new ResultWrapper( $this, $result );
3118                 }
3119         }
3120
3121         public function ping( &$rtt = null ) {
3122                 // Avoid hitting the server if it was hit recently
3123                 if ( $this->isOpen() && ( microtime( true ) - $this->lastPing ) < self::PING_TTL ) {
3124                         if ( !func_num_args() || $this->mRTTEstimate > 0 ) {
3125                                 $rtt = $this->mRTTEstimate;
3126                                 return true; // don't care about $rtt
3127                         }
3128                 }
3129
3130                 // This will reconnect if possible or return false if not
3131                 $this->clearFlag( self::DBO_TRX, self::REMEMBER_PRIOR );
3132                 $ok = ( $this->query( self::PING_QUERY, __METHOD__, true ) !== false );
3133                 $this->restoreFlags( self::RESTORE_PRIOR );
3134
3135                 if ( $ok ) {
3136                         $rtt = $this->mRTTEstimate;
3137                 }
3138
3139                 return $ok;
3140         }
3141
3142         /**
3143          * Close existing database connection and open a new connection
3144          *
3145          * @return bool True if new connection is opened successfully, false if error
3146          */
3147         protected function reconnect() {
3148                 $this->closeConnection();
3149                 $this->mOpened = false;
3150                 $this->mConn = false;
3151                 try {
3152                         $this->open( $this->mServer, $this->mUser, $this->mPassword, $this->mDBname );
3153                         $this->lastPing = microtime( true );
3154                         $ok = true;
3155                 } catch ( DBConnectionError $e ) {
3156                         $ok = false;
3157                 }
3158
3159                 return $ok;
3160         }
3161
3162         public function getSessionLagStatus() {
3163                 return $this->getTransactionLagStatus() ?: $this->getApproximateLagStatus();
3164         }
3165
3166         /**
3167          * Get the replica DB lag when the current transaction started
3168          *
3169          * This is useful when transactions might use snapshot isolation
3170          * (e.g. REPEATABLE-READ in innodb), so the "real" lag of that data
3171          * is this lag plus transaction duration. If they don't, it is still
3172          * safe to be pessimistic. This returns null if there is no transaction.
3173          *
3174          * @return array|null ('lag': seconds or false on error, 'since': UNIX timestamp of BEGIN)
3175          * @since 1.27
3176          */
3177         protected function getTransactionLagStatus() {
3178                 return $this->mTrxLevel
3179                         ? [ 'lag' => $this->mTrxReplicaLag, 'since' => $this->trxTimestamp() ]
3180                         : null;
3181         }
3182
3183         /**
3184          * Get a replica DB lag estimate for this server
3185          *
3186          * @return array ('lag': seconds or false on error, 'since': UNIX timestamp of estimate)
3187          * @since 1.27
3188          */
3189         protected function getApproximateLagStatus() {
3190                 return [
3191                         'lag'   => $this->getLBInfo( 'replica' ) ? $this->getLag() : 0,
3192                         'since' => microtime( true )
3193                 ];
3194         }
3195
3196         /**
3197          * Merge the result of getSessionLagStatus() for several DBs
3198          * using the most pessimistic values to estimate the lag of
3199          * any data derived from them in combination
3200          *
3201          * This is information is useful for caching modules
3202          *
3203          * @see WANObjectCache::set()
3204          * @see WANObjectCache::getWithSetCallback()
3205          *
3206          * @param IDatabase $db1
3207          * @param IDatabase $dbs,...
3208          * @return array Map of values:
3209          *   - lag: highest lag of any of the DBs or false on error (e.g. replication stopped)
3210          *   - since: oldest UNIX timestamp of any of the DB lag estimates
3211          *   - pending: whether any of the DBs have uncommitted changes
3212          * @since 1.27
3213          */
3214         public static function getCacheSetOptions( IDatabase $db1 ) {
3215                 $res = [ 'lag' => 0, 'since' => INF, 'pending' => false ];
3216                 foreach ( func_get_args() as $db ) {
3217                         /** @var IDatabase $db */
3218                         $status = $db->getSessionLagStatus();
3219                         if ( $status['lag'] === false ) {
3220                                 $res['lag'] = false;
3221                         } elseif ( $res['lag'] !== false ) {
3222                                 $res['lag'] = max( $res['lag'], $status['lag'] );
3223                         }
3224                         $res['since'] = min( $res['since'], $status['since'] );
3225                         $res['pending'] = $res['pending'] ?: $db->writesPending();
3226                 }
3227
3228                 return $res;
3229         }
3230
3231         public function getLag() {
3232                 return 0;
3233         }
3234
3235         public function maxListLen() {
3236                 return 0;
3237         }
3238
3239         public function encodeBlob( $b ) {
3240                 return $b;
3241         }
3242
3243         public function decodeBlob( $b ) {
3244                 if ( $b instanceof Blob ) {
3245                         $b = $b->fetch();
3246                 }
3247                 return $b;
3248         }
3249
3250         public function setSessionOptions( array $options ) {
3251         }
3252
3253         public function sourceFile(
3254                 $filename,
3255                 callable $lineCallback = null,
3256                 callable $resultCallback = null,
3257                 $fname = false,
3258                 callable $inputCallback = null
3259         ) {
3260                 MediaWiki\suppressWarnings();
3261                 $fp = fopen( $filename, 'r' );
3262                 MediaWiki\restoreWarnings();
3263
3264                 if ( false === $fp ) {
3265                         throw new RuntimeException( "Could not open \"{$filename}\".\n" );
3266                 }
3267
3268                 if ( !$fname ) {
3269                         $fname = __METHOD__ . "( $filename )";
3270                 }
3271
3272                 try {
3273                         $error = $this->sourceStream(
3274                                 $fp, $lineCallback, $resultCallback, $fname, $inputCallback );
3275                 } catch ( Exception $e ) {
3276                         fclose( $fp );
3277                         throw $e;
3278                 }
3279
3280                 fclose( $fp );
3281
3282                 return $error;
3283         }
3284
3285         public function setSchemaVars( $vars ) {
3286                 $this->mSchemaVars = $vars;
3287         }
3288
3289         public function sourceStream(
3290                 $fp,
3291                 callable $lineCallback = null,
3292                 callable $resultCallback = null,
3293                 $fname = __METHOD__,
3294                 callable $inputCallback = null
3295         ) {
3296                 $cmd = '';
3297
3298                 while ( !feof( $fp ) ) {
3299                         if ( $lineCallback ) {
3300                                 call_user_func( $lineCallback );
3301                         }
3302
3303                         $line = trim( fgets( $fp ) );
3304
3305                         if ( $line == '' ) {
3306                                 continue;
3307                         }
3308
3309                         if ( '-' == $line[0] && '-' == $line[1] ) {
3310                                 continue;
3311                         }
3312
3313                         if ( $cmd != '' ) {
3314                                 $cmd .= ' ';
3315                         }
3316
3317                         $done = $this->streamStatementEnd( $cmd, $line );
3318
3319                         $cmd .= "$line\n";
3320
3321                         if ( $done || feof( $fp ) ) {
3322                                 $cmd = $this->replaceVars( $cmd );
3323
3324                                 if ( !$inputCallback || call_user_func( $inputCallback, $cmd ) ) {
3325                                         $res = $this->query( $cmd, $fname );
3326
3327                                         if ( $resultCallback ) {
3328                                                 call_user_func( $resultCallback, $res, $this );
3329                                         }
3330
3331                                         if ( false === $res ) {
3332                                                 $err = $this->lastError();
3333
3334                                                 return "Query \"{$cmd}\" failed with error code \"$err\".\n";
3335                                         }
3336                                 }
3337                                 $cmd = '';
3338                         }
3339                 }
3340
3341                 return true;
3342         }
3343
3344         /**
3345          * Called by sourceStream() to check if we've reached a statement end
3346          *
3347          * @param string &$sql SQL assembled so far
3348          * @param string &$newLine New line about to be added to $sql
3349          * @return bool Whether $newLine contains end of the statement
3350          */
3351         public function streamStatementEnd( &$sql, &$newLine ) {
3352                 if ( $this->delimiter ) {
3353                         $prev = $newLine;
3354                         $newLine = preg_replace(
3355                                 '/' . preg_quote( $this->delimiter, '/' ) . '$/', '', $newLine );
3356                         if ( $newLine != $prev ) {
3357                                 return true;
3358                         }
3359                 }
3360
3361                 return false;
3362         }
3363
3364         /**
3365          * Database independent variable replacement. Replaces a set of variables
3366          * in an SQL statement with their contents as given by $this->getSchemaVars().
3367          *
3368          * Supports '{$var}' `{$var}` and / *$var* / (without the spaces) style variables.
3369          *
3370          * - '{$var}' should be used for text and is passed through the database's
3371          *   addQuotes method.
3372          * - `{$var}` should be used for identifiers (e.g. table and database names).
3373          *   It is passed through the database's addIdentifierQuotes method which
3374          *   can be overridden if the database uses something other than backticks.
3375          * - / *_* / or / *$wgDBprefix* / passes the name that follows through the
3376          *   database's tableName method.
3377          * - / *i* / passes the name that follows through the database's indexName method.
3378          * - In all other cases, / *$var* / is left unencoded. Except for table options,
3379          *   its use should be avoided. In 1.24 and older, string encoding was applied.
3380          *
3381          * @param string $ins SQL statement to replace variables in
3382          * @return string The new SQL statement with variables replaced
3383          */
3384         protected function replaceVars( $ins ) {
3385                 $vars = $this->getSchemaVars();
3386                 return preg_replace_callback(
3387                         '!
3388                                 /\* (\$wgDBprefix|[_i]) \*/ (\w*) | # 1-2. tableName, indexName
3389                                 \'\{\$ (\w+) }\'                  | # 3. addQuotes
3390                                 `\{\$ (\w+) }`                    | # 4. addIdentifierQuotes
3391                                 /\*\$ (\w+) \*/                     # 5. leave unencoded
3392                         !x',
3393                         function ( $m ) use ( $vars ) {
3394                                 // Note: Because of <https://bugs.php.net/bug.php?id=51881>,
3395                                 // check for both nonexistent keys *and* the empty string.
3396                                 if ( isset( $m[1] ) && $m[1] !== '' ) {
3397                                         if ( $m[1] === 'i' ) {
3398                                                 return $this->indexName( $m[2] );
3399                                         } else {
3400                                                 return $this->tableName( $m[2] );
3401                                         }
3402                                 } elseif ( isset( $m[3] ) && $m[3] !== '' && array_key_exists( $m[3], $vars ) ) {
3403                                         return $this->addQuotes( $vars[$m[3]] );
3404                                 } elseif ( isset( $m[4] ) && $m[4] !== '' && array_key_exists( $m[4], $vars ) ) {
3405                                         return $this->addIdentifierQuotes( $vars[$m[4]] );
3406                                 } elseif ( isset( $m[5] ) && $m[5] !== '' && array_key_exists( $m[5], $vars ) ) {
3407                                         return $vars[$m[5]];
3408                                 } else {
3409                                         return $m[0];
3410                                 }
3411                         },
3412                         $ins
3413                 );
3414         }
3415
3416         /**
3417          * Get schema variables. If none have been set via setSchemaVars(), then
3418          * use some defaults from the current object.
3419          *
3420          * @return array
3421          */
3422         protected function getSchemaVars() {
3423                 if ( $this->mSchemaVars ) {
3424                         return $this->mSchemaVars;
3425                 } else {
3426                         return $this->getDefaultSchemaVars();
3427                 }
3428         }
3429
3430         /**
3431          * Get schema variables to use if none have been set via setSchemaVars().
3432          *
3433          * Override this in derived classes to provide variables for tables.sql
3434          * and SQL patch files.
3435          *
3436          * @return array
3437          */
3438         protected function getDefaultSchemaVars() {
3439                 return [];
3440         }
3441
3442         public function lockIsFree( $lockName, $method ) {
3443                 return true;
3444         }
3445
3446         public function lock( $lockName, $method, $timeout = 5 ) {
3447                 $this->mNamedLocksHeld[$lockName] = 1;
3448
3449                 return true;
3450         }
3451
3452         public function unlock( $lockName, $method ) {
3453                 unset( $this->mNamedLocksHeld[$lockName] );
3454
3455                 return true;
3456         }
3457
3458         public function getScopedLockAndFlush( $lockKey, $fname, $timeout ) {
3459                 if ( $this->writesOrCallbacksPending() ) {
3460                         // This only flushes transactions to clear snapshots, not to write data
3461                         $fnames = implode( ', ', $this->pendingWriteAndCallbackCallers() );
3462                         throw new DBUnexpectedError(
3463                                 $this,
3464                                 "$fname: Cannot flush pre-lock snapshot because writes are pending ($fnames)."
3465                         );
3466                 }
3467
3468                 if ( !$this->lock( $lockKey, $fname, $timeout ) ) {
3469                         return null;
3470                 }
3471
3472                 $unlocker = new ScopedCallback( function () use ( $lockKey, $fname ) {
3473                         if ( $this->trxLevel() ) {
3474                                 // There is a good chance an exception was thrown, causing any early return
3475                                 // from the caller. Let any error handler get a chance to issue rollback().
3476                                 // If there isn't one, let the error bubble up and trigger server-side rollback.
3477                                 $this->onTransactionResolution(
3478                                         function () use ( $lockKey, $fname ) {
3479                                                 $this->unlock( $lockKey, $fname );
3480                                         },
3481                                         $fname
3482                                 );
3483                         } else {
3484                                 $this->unlock( $lockKey, $fname );
3485                         }
3486                 } );
3487
3488                 $this->commit( $fname, self::FLUSHING_INTERNAL );
3489
3490                 return $unlocker;
3491         }
3492
3493         public function namedLocksEnqueue() {
3494                 return false;
3495         }
3496
3497         public function tableLocksHaveTransactionScope() {
3498                 return true;
3499         }
3500
3501         final public function lockTables( array $read, array $write, $method ) {
3502                 if ( $this->writesOrCallbacksPending() ) {
3503                         throw new DBUnexpectedError( $this, "Transaction writes or callbacks still pending." );
3504                 }
3505
3506                 if ( $this->tableLocksHaveTransactionScope() ) {
3507                         $this->startAtomic( $method );
3508                 }
3509
3510                 return $this->doLockTables( $read, $write, $method );
3511         }
3512
3513         /**
3514          * Helper function for lockTables() that handles the actual table locking
3515          *
3516          * @param array $read Array of tables to lock for read access
3517          * @param array $write Array of tables to lock for write access
3518          * @param string $method Name of caller
3519          * @return true
3520          */
3521         protected function doLockTables( array $read, array $write, $method ) {
3522                 return true;
3523         }
3524
3525         final public function unlockTables( $method ) {
3526                 if ( $this->tableLocksHaveTransactionScope() ) {
3527                         $this->endAtomic( $method );
3528
3529                         return true; // locks released on COMMIT/ROLLBACK
3530                 }
3531
3532                 return $this->doUnlockTables( $method );
3533         }
3534
3535         /**
3536          * Helper function for unlockTables() that handles the actual table unlocking
3537          *
3538          * @param string $method Name of caller
3539          * @return true
3540          */
3541         protected function doUnlockTables( $method ) {
3542                 return true;
3543         }
3544
3545         /**
3546          * Delete a table
3547          * @param string $tableName
3548          * @param string $fName
3549          * @return bool|ResultWrapper
3550          * @since 1.18
3551          */
3552         public function dropTable( $tableName, $fName = __METHOD__ ) {
3553                 if ( !$this->tableExists( $tableName, $fName ) ) {
3554                         return false;
3555                 }
3556                 $sql = "DROP TABLE " . $this->tableName( $tableName ) . " CASCADE";
3557
3558                 return $this->query( $sql, $fName );
3559         }
3560
3561         public function getInfinity() {
3562                 return 'infinity';
3563         }
3564
3565         public function encodeExpiry( $expiry ) {
3566                 return ( $expiry == '' || $expiry == 'infinity' || $expiry == $this->getInfinity() )
3567                         ? $this->getInfinity()
3568                         : $this->timestamp( $expiry );
3569         }
3570
3571         public function decodeExpiry( $expiry, $format = TS_MW ) {
3572                 if ( $expiry == '' || $expiry == 'infinity' || $expiry == $this->getInfinity() ) {
3573                         return 'infinity';
3574                 }
3575
3576                 return ConvertibleTimestamp::convert( $format, $expiry );
3577         }
3578
3579         public function setBigSelects( $value = true ) {
3580                 // no-op
3581         }
3582
3583         public function isReadOnly() {
3584                 return ( $this->getReadOnlyReason() !== false );
3585         }
3586
3587         /**
3588          * @return string|bool Reason this DB is read-only or false if it is not
3589          */
3590         protected function getReadOnlyReason() {
3591                 $reason = $this->getLBInfo( 'readOnlyReason' );
3592
3593                 return is_string( $reason ) ? $reason : false;
3594         }
3595
3596         public function setTableAliases( array $aliases ) {
3597                 $this->tableAliases = $aliases;
3598         }
3599
3600         /**
3601          * @return bool Whether a DB user is required to access the DB
3602          * @since 1.28
3603          */
3604         protected function requiresDatabaseUser() {
3605                 return true;
3606         }
3607
3608         /**
3609          * Get the underlying binding handle, mConn
3610          *
3611          * Makes sure that mConn is set (disconnects and ping() failure can unset it).
3612          * This catches broken callers than catch and ignore disconnection exceptions.
3613          * Unlike checking isOpen(), this is safe to call inside of open().
3614          *
3615          * @return resource|object
3616          * @throws DBUnexpectedError
3617          * @since 1.26
3618          */
3619         protected function getBindingHandle() {
3620                 if ( !$this->mConn ) {
3621                         throw new DBUnexpectedError(
3622                                 $this,
3623                                 'DB connection was already closed or the connection dropped.'
3624                         );
3625                 }
3626
3627                 return $this->mConn;
3628         }
3629
3630         /**
3631          * @since 1.19
3632          * @return string
3633          */
3634         public function __toString() {
3635                 return (string)$this->mConn;
3636         }
3637
3638         /**
3639          * Make sure that copies do not share the same client binding handle
3640          * @throws DBConnectionError
3641          */
3642         public function __clone() {
3643                 $this->connLogger->warning(
3644                         "Cloning " . static::class . " is not recomended; forking connection:\n" .
3645                         ( new RuntimeException() )->getTraceAsString()
3646                 );
3647
3648                 if ( $this->isOpen() ) {
3649                         // Open a new connection resource without messing with the old one
3650                         $this->mOpened = false;
3651                         $this->mConn = false;
3652                         $this->mTrxEndCallbacks = []; // don't copy
3653                         $this->handleSessionLoss(); // no trx or locks anymore
3654                         $this->open( $this->mServer, $this->mUser, $this->mPassword, $this->mDBname );
3655                         $this->lastPing = microtime( true );
3656                 }
3657         }
3658
3659         /**
3660          * Called by serialize. Throw an exception when DB connection is serialized.
3661          * This causes problems on some database engines because the connection is
3662          * not restored on unserialize.
3663          */
3664         public function __sleep() {
3665                 throw new RuntimeException( 'Database serialization may cause problems, since ' .
3666                         'the connection is not restored on wakeup.' );
3667         }
3668
3669         /**
3670          * Run a few simple sanity checks and close dangling connections
3671          */
3672         public function __destruct() {
3673                 if ( $this->mTrxLevel && $this->mTrxDoneWrites ) {
3674                         trigger_error( "Uncommitted DB writes (transaction from {$this->mTrxFname})." );
3675                 }
3676
3677                 $danglingWriters = $this->pendingWriteAndCallbackCallers();
3678                 if ( $danglingWriters ) {
3679                         $fnames = implode( ', ', $danglingWriters );
3680                         trigger_error( "DB transaction writes or callbacks still pending ($fnames)." );
3681                 }
3682
3683                 if ( $this->mConn ) {
3684                         // Avoid connection leaks for sanity. Normally, resources close at script completion.
3685                         // The connection might already be closed in zend/hhvm by now, so suppress warnings.
3686                         \MediaWiki\suppressWarnings();
3687                         $this->closeConnection();
3688                         \MediaWiki\restoreWarnings();
3689                         $this->mConn = false;
3690                         $this->mOpened = false;
3691                 }
3692         }
3693 }
3694
3695 class_alias( Database::class, 'DatabaseBase' ); // b/c for old name
3696 class_alias( Database::class, 'Database' ); // b/c global alias