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 = .010;
  58         const SLOW_WRITE_SEC = .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 integer */
 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 integer Number of write queries for the current transaction
 201          */
 202         private $mTrxWriteQueryCount = 0;
 203         /**
 204          * @var integer 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 integer 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 ( $this->mTrxIdleCallbacks || $this->mTrxEndCallbacks ) { // sanity
 762                         throw new RuntimeException( "Transaction callbacks still pending." );
 763                 } else {
 764                         $closed = true;
 765                 }
 766                 $this->mOpened = false;
 767
 768                 return $closed;
 769         }
 770
 771         /**
 772          * Make sure isOpen() returns true as a sanity check
 773          *
 774          * @throws DBUnexpectedError
 775          */
 776         protected function assertOpen() {
 777                 if ( !$this->isOpen() ) {
 778                         throw new DBUnexpectedError( $this, "DB connection was already closed." );
 779                 }
 780         }
 781
 782         /**
 783          * Closes underlying database connection
 784          * @since 1.20
 785          * @return bool Whether connection was closed successfully
 786          */
 787         abstract protected function closeConnection();
 788
 789         public function reportConnectionError( $error = 'Unknown error' ) {
 790                 $myError = $this->lastError();
 791                 if ( $myError ) {
 792                         $error = $myError;
 793                 }
 794
 795                 # New method
 796                 throw new DBConnectionError( $this, $error );
 797         }
 798
 799         /**
 800          * The DBMS-dependent part of query()
 801          *
 802          * @param string $sql SQL query.
 803          * @return ResultWrapper|bool Result object to feed to fetchObject,
 804          *   fetchRow, ...; or false on failure
 805          */
 806         abstract protected function doQuery( $sql );
 807
 808         /**
 809          * Determine whether a query writes to the DB.
 810          * Should return true if unsure.
 811          *
 812          * @param string $sql
 813          * @return bool
 814          */
 815         protected function isWriteQuery( $sql ) {
 816                 return !preg_match(
 817                         '/^(?:SELECT|BEGIN|ROLLBACK|COMMIT|SET|SHOW|EXPLAIN|\(SELECT)\b/i', $sql );
 818         }
 819
 820         /**
 821          * @param $sql
 822          * @return string|null
 823          */
 824         protected function getQueryVerb( $sql ) {
 825                 return preg_match( '/^\s*([a-z]+)/i', $sql, $m ) ? strtoupper( $m[1] ) : null;
 826         }
 827
 828         /**
 829          * Determine whether a SQL statement is sensitive to isolation level.
 830          * A SQL statement is considered transactable if its result could vary
 831          * depending on the transaction isolation level. Operational commands
 832          * such as 'SET' and 'SHOW' are not considered to be transactable.
 833          *
 834          * @param string $sql
 835          * @return bool
 836          */
 837         protected function isTransactableQuery( $sql ) {
 838                 return !in_array(
 839                         $this->getQueryVerb( $sql ),
 840                         [ 'BEGIN', 'COMMIT', 'ROLLBACK', 'SHOW', 'SET', 'CREATE', 'ALTER' ],
 841                         true
 842                 );
 843         }
 844
 845         /**
 846          * @param string $sql A SQL query
 847          * @return bool Whether $sql is SQL for TEMPORARY table operation
 848          */
 849         protected function registerTempTableOperation( $sql ) {
 850                 if ( preg_match(
 851                         '/^CREATE\s+TEMPORARY\s+TABLE\s+(?:IF\s+NOT\s+EXISTS\s+)?[`"\']?(\w+)[`"\']?/i',
 852                         $sql,
 853                         $matches
 854                 ) ) {
 855                         $this->mSessionTempTables[$matches[1]] = 1;
 856
 857                         return true;
 858                 } elseif ( preg_match(
 859                         '/^DROP\s+(?:TEMPORARY\s+)?TABLE\s+(?:IF\s+EXISTS\s+)?[`"\']?(\w+)[`"\']?/i',
 860                         $sql,
 861                         $matches
 862                 ) ) {
 863                         $isTemp = isset( $this->mSessionTempTables[$matches[1]] );
 864                         unset( $this->mSessionTempTables[$matches[1]] );
 865
 866                         return $isTemp;
 867                 } elseif ( preg_match(
 868                         '/^TRUNCATE\s+(?:TEMPORARY\s+)?TABLE\s+(?:IF\s+EXISTS\s+)?[`"\']?(\w+)[`"\']?/i',
 869                         $sql,
 870                         $matches
 871                 ) ) {
 872                         return isset( $this->mSessionTempTables[$matches[1]] );
 873                 } elseif ( preg_match(
 874                         '/^(?:INSERT\s+(?:\w+\s+)?INTO|UPDATE|DELETE\s+FROM)\s+[`"\']?(\w+)[`"\']?/i',
 875                         $sql,
 876                         $matches
 877                 ) ) {
 878                         return isset( $this->mSessionTempTables[$matches[1]] );
 879                 }
 880
 881                 return false;
 882         }
 883
 884         public function query( $sql, $fname = __METHOD__, $tempIgnore = false ) {
 885                 $priorWritesPending = $this->writesOrCallbacksPending();
 886                 $this->mLastQuery = $sql;
 887
 888                 $isWrite = $this->isWriteQuery( $sql );
 889                 if ( $isWrite ) {
 890                         $isNonTempWrite = !$this->registerTempTableOperation( $sql );
 891                 } else {
 892                         $isNonTempWrite = false;
 893                 }
 894
 895                 if ( $isWrite ) {
 896                         # In theory, non-persistent writes are allowed in read-only mode, but due to things
 897                         # like https://bugs.mysql.com/bug.php?id=33669 that might not work anyway...
 898                         $reason = $this->getReadOnlyReason();
 899                         if ( $reason !== false ) {
 900                                 throw new DBReadOnlyError( $this, "Database is read-only: $reason" );
 901                         }
 902                         # Set a flag indicating that writes have been done
 903                         $this->mLastWriteTime = microtime( true );
 904                 }
 905
 906                 # Add trace comment to the begin of the sql string, right after the operator.
 907                 # Or, for one-word queries (like "BEGIN" or COMMIT") add it to the end (T44598)
 908                 $commentedSql = preg_replace( '/\s|$/', " /* $fname {$this->agent} */ ", $sql, 1 );
 909
 910                 # Start implicit transactions that wrap the request if DBO_TRX is enabled
 911                 if ( !$this->mTrxLevel && $this->getFlag( self::DBO_TRX )
 912                         && $this->isTransactableQuery( $sql )
 913                 ) {
 914                         $this->begin( __METHOD__ . " ($fname)", self::TRANSACTION_INTERNAL );
 915                         $this->mTrxAutomatic = true;
 916                 }
 917
 918                 # Keep track of whether the transaction has write queries pending
 919                 if ( $this->mTrxLevel && !$this->mTrxDoneWrites && $isWrite ) {
 920                         $this->mTrxDoneWrites = true;
 921                         $this->trxProfiler->transactionWritingIn(
 922                                 $this->mServer, $this->mDBname, $this->mTrxShortId );
 923                 }
 924
 925                 if ( $this->getFlag( self::DBO_DEBUG ) ) {
 926                         $this->queryLogger->debug( "{$this->mDBname} {$commentedSql}" );
 927                 }
 928
 929                 # Avoid fatals if close() was called
 930                 $this->assertOpen();
 931
 932                 # Send the query to the server
 933                 $ret = $this->doProfiledQuery( $sql, $commentedSql, $isNonTempWrite, $fname );
 934
 935                 # Try reconnecting if the connection was lost
 936                 if ( false === $ret && $this->wasErrorReissuable() ) {
 937                         $recoverable = $this->canRecoverFromDisconnect( $sql, $priorWritesPending );
 938                         # Stash the last error values before anything might clear them
 939                         $lastError = $this->lastError();
 940                         $lastErrno = $this->lastErrno();
 941                         # Update state tracking to reflect transaction loss due to disconnection
 942                         $this->handleSessionLoss();
 943                         if ( $this->reconnect() ) {
 944                                 $msg = __METHOD__ . ": lost connection to {$this->getServer()}; reconnected";
 945                                 $this->connLogger->warning( $msg );
 946                                 $this->queryLogger->warning(
 947                                         "$msg:\n" . ( new RuntimeException() )->getTraceAsString() );
 948
 949                                 if ( !$recoverable ) {
 950                                         # Callers may catch the exception and continue to use the DB
 951                                         $this->reportQueryError( $lastError, $lastErrno, $sql, $fname );
 952                                 } else {
 953                                         # Should be safe to silently retry the query
 954                                         $ret = $this->doProfiledQuery( $sql, $commentedSql, $isNonTempWrite, $fname );
 955                                 }
 956                         } else {
 957                                 $msg = __METHOD__ . ": lost connection to {$this->getServer()} permanently";
 958                                 $this->connLogger->error( $msg );
 959                         }
 960                 }
 961
 962                 if ( false === $ret ) {
 963                         # Deadlocks cause the entire transaction to abort, not just the statement.
 964                         # https://dev.mysql.com/doc/refman/5.7/en/innodb-error-handling.html
 965                         # https://www.postgresql.org/docs/9.1/static/explicit-locking.html
 966                         if ( $this->wasDeadlock() ) {
 967                                 if ( $this->explicitTrxActive() || $priorWritesPending ) {
 968                                         $tempIgnore = false; // not recoverable
 969                                 }
 970                                 # Update state tracking to reflect transaction loss
 971                                 $this->handleSessionLoss();
 972                         }
 973
 974                         $this->reportQueryError(
 975                                 $this->lastError(), $this->lastErrno(), $sql, $fname, $tempIgnore );
 976                 }
 977
 978                 $res = $this->resultObject( $ret );
 979
 980                 return $res;
 981         }
 982
 983         /**
 984          * Helper method for query() that handles profiling and logging and sends
 985          * the query to doQuery()
 986          *
 987          * @param string $sql Original SQL query
 988          * @param string $commentedSql SQL query with debugging/trace comment
 989          * @param bool $isWrite Whether the query is a (non-temporary) write operation
 990          * @param string $fname Name of the calling function
 991          * @return bool|ResultWrapper True for a successful write query, ResultWrapper
 992          *     object for a successful read query, or false on failure
 993          */
 994         private function doProfiledQuery( $sql, $commentedSql, $isWrite, $fname ) {
 995                 $isMaster = !is_null( $this->getLBInfo( 'master' ) );
 996                 # generalizeSQL() will probably cut down the query to reasonable
 997                 # logging size most of the time. The substr is really just a sanity check.
 998                 if ( $isMaster ) {
 999                         $queryProf = 'query-m: ' . substr( self::generalizeSQL( $sql ), 0, 255 );
1000                 } else {
1001                         $queryProf = 'query: ' . substr( self::generalizeSQL( $sql ), 0, 255 );
1002                 }
1003
1004                 # Include query transaction state
1005                 $queryProf .= $this->mTrxShortId ? " [TRX#{$this->mTrxShortId}]" : "";
1006
1007                 $startTime = microtime( true );
1008                 if ( $this->profiler ) {
1009                         call_user_func( [ $this->profiler, 'profileIn' ], $queryProf );
1010                 }
1011                 $ret = $this->doQuery( $commentedSql );
1012                 if ( $this->profiler ) {
1013                         call_user_func( [ $this->profiler, 'profileOut' ], $queryProf );
1014                 }
1015                 $queryRuntime = max( microtime( true ) - $startTime, 0.0 );
1016
1017                 unset( $queryProfSection ); // profile out (if set)
1018
1019                 if ( $ret !== false ) {
1020                         $this->lastPing = $startTime;
1021                         if ( $isWrite && $this->mTrxLevel ) {
1022                                 $this->updateTrxWriteQueryTime( $sql, $queryRuntime, $this->affectedRows() );
1023                                 $this->mTrxWriteCallers[] = $fname;
1024                         }
1025                 }
1026
1027                 if ( $sql === self::PING_QUERY ) {
1028                         $this->mRTTEstimate = $queryRuntime;
1029                 }
1030
1031                 $this->trxProfiler->recordQueryCompletion(
1032                         $queryProf, $startTime, $isWrite, $this->affectedRows()
1033                 );
1034                 $this->queryLogger->debug( $sql, [
1035                         'method' => $fname,
1036                         'master' => $isMaster,
1037                         'runtime' => $queryRuntime,
1038                 ] );
1039
1040                 return $ret;
1041         }
1042
1043         /**
1044          * Update the estimated run-time of a query, not counting large row lock times
1045          *
1046          * LoadBalancer can be set to rollback transactions that will create huge replication
1047          * lag. It bases this estimate off of pendingWriteQueryDuration(). Certain simple
1048          * queries, like inserting a row can take a long time due to row locking. This method
1049          * uses some simple heuristics to discount those cases.
1050          *
1051          * @param string $sql A SQL write query
1052          * @param float $runtime Total runtime, including RTT
1053          * @param integer $affected Affected row count
1054          */
1055         private function updateTrxWriteQueryTime( $sql, $runtime, $affected ) {
1056                 // Whether this is indicative of replica DB runtime (except for RBR or ws_repl)
1057                 $indicativeOfReplicaRuntime = true;
1058                 if ( $runtime > self::SLOW_WRITE_SEC ) {
1059                         $verb = $this->getQueryVerb( $sql );
1060                         // insert(), upsert(), replace() are fast unless bulky in size or blocked on locks
1061                         if ( $verb === 'INSERT' ) {
1062                                 $indicativeOfReplicaRuntime = $this->affectedRows() > self::SMALL_WRITE_ROWS;
1063                         } elseif ( $verb === 'REPLACE' ) {
1064                                 $indicativeOfReplicaRuntime = $this->affectedRows() > self::SMALL_WRITE_ROWS / 2;
1065                         }
1066                 }
1067
1068                 $this->mTrxWriteDuration += $runtime;
1069                 $this->mTrxWriteQueryCount += 1;
1070                 $this->mTrxWriteAffectedRows += $affected;
1071                 if ( $indicativeOfReplicaRuntime ) {
1072                         $this->mTrxWriteAdjDuration += $runtime;
1073                         $this->mTrxWriteAdjQueryCount += 1;
1074                 }
1075         }
1076
1077         /**
1078          * Determine whether or not it is safe to retry queries after a database
1079          * connection is lost
1080          *
1081          * @param string $sql SQL query
1082          * @param bool $priorWritesPending Whether there is a transaction open with
1083          *     possible write queries or transaction pre-commit/idle callbacks
1084          *     waiting on it to finish.
1085          * @return bool True if it is safe to retry the query, false otherwise
1086          */
1087         private function canRecoverFromDisconnect( $sql, $priorWritesPending ) {
1088                 # Transaction dropped; this can mean lost writes, or REPEATABLE-READ snapshots.
1089                 # Dropped connections also mean that named locks are automatically released.
1090                 # Only allow error suppression in autocommit mode or when the lost transaction
1091                 # didn't matter anyway (aside from DBO_TRX snapshot loss).
1092                 if ( $this->mNamedLocksHeld ) {
1093                         return false; // possible critical section violation
1094                 } elseif ( $sql === 'COMMIT' ) {
1095                         return !$priorWritesPending; // nothing written anyway? (T127428)
1096                 } elseif ( $sql === 'ROLLBACK' ) {
1097                         return true; // transaction lost...which is also what was requested :)
1098                 } elseif ( $this->explicitTrxActive() ) {
1099                         return false; // don't drop atomocity
1100                 } elseif ( $priorWritesPending ) {
1101                         return false; // prior writes lost from implicit transaction
1102                 }
1103
1104                 return true;
1105         }
1106
1107         /**
1108          * Clean things up after transaction loss due to disconnection
1109          *
1110          * @return null|Exception
1111          */
1112         private function handleSessionLoss() {
1113                 $this->mTrxLevel = 0;
1114                 $this->mTrxIdleCallbacks = []; // T67263
1115                 $this->mTrxPreCommitCallbacks = []; // T67263
1116                 $this->mSessionTempTables = [];
1117                 $this->mNamedLocksHeld = [];
1118                 try {
1119                         // Handle callbacks in mTrxEndCallbacks
1120                         $this->runOnTransactionIdleCallbacks( self::TRIGGER_ROLLBACK );
1121                         $this->runTransactionListenerCallbacks( self::TRIGGER_ROLLBACK );
1122                         return null;
1123                 } catch ( Exception $e ) {
1124                         // Already logged; move on...
1125                         return $e;
1126                 }
1127         }
1128
1129         public function reportQueryError( $error, $errno, $sql, $fname, $tempIgnore = false ) {
1130                 if ( $this->ignoreErrors() || $tempIgnore ) {
1131                         $this->queryLogger->debug( "SQL ERROR (ignored): $error\n" );
1132                 } else {
1133                         $sql1line = mb_substr( str_replace( "\n", "\\n", $sql ), 0, 5 * 1024 );
1134                         $this->queryLogger->error(
1135                                 "{fname}\t{db_server}\t{errno}\t{error}\t{sql1line}",
1136                                 $this->getLogContext( [
1137                                         'method' => __METHOD__,
1138                                         'errno' => $errno,
1139                                         'error' => $error,
1140                                         'sql1line' => $sql1line,
1141                                         'fname' => $fname,
1142                                 ] )
1143                         );
1144                         $this->queryLogger->debug( "SQL ERROR: " . $error . "\n" );
1145                         throw new DBQueryError( $this, $error, $errno, $sql, $fname );
1146                 }
1147         }
1148
1149         public function freeResult( $res ) {
1150         }
1151
1152         public function selectField(
1153                 $table, $var, $cond = '', $fname = __METHOD__, $options = [], $join_conds = []
1154         ) {
1155                 if ( $var === '*' ) { // sanity
1156                         throw new DBUnexpectedError( $this, "Cannot use a * field: got '$var'" );
1157                 }
1158
1159                 if ( !is_array( $options ) ) {
1160                         $options = [ $options ];
1161                 }
1162
1163                 $options['LIMIT'] = 1;
1164
1165                 $res = $this->select( $table, $var, $cond, $fname, $options, $join_conds );
1166                 if ( $res === false || !$this->numRows( $res ) ) {
1167                         return false;
1168                 }
1169
1170                 $row = $this->fetchRow( $res );
1171
1172                 if ( $row !== false ) {
1173                         return reset( $row );
1174                 } else {
1175                         return false;
1176                 }
1177         }
1178
1179         public function selectFieldValues(
1180                 $table, $var, $cond = '', $fname = __METHOD__, $options = [], $join_conds = []
1181         ) {
1182                 if ( $var === '*' ) { // sanity
1183                         throw new DBUnexpectedError( $this, "Cannot use a * field" );
1184                 } elseif ( !is_string( $var ) ) { // sanity
1185                         throw new DBUnexpectedError( $this, "Cannot use an array of fields" );
1186                 }
1187
1188                 if ( !is_array( $options ) ) {
1189                         $options = [ $options ];
1190                 }
1191
1192                 $res = $this->select( $table, $var, $cond, $fname, $options, $join_conds );
1193                 if ( $res === false ) {
1194                         return false;
1195                 }
1196
1197                 $values = [];
1198                 foreach ( $res as $row ) {
1199                         $values[] = $row->$var;
1200                 }
1201
1202                 return $values;
1203         }
1204
1205         /**
1206          * Returns an optional USE INDEX clause to go after the table, and a
1207          * string to go at the end of the query.
1208          *
1209          * @param array $options Associative array of options to be turned into
1210          *   an SQL query, valid keys are listed in the function.
1211          * @return array
1212          * @see Database::select()
1213          */
1214         protected function makeSelectOptions( $options ) {
1215                 $preLimitTail = $postLimitTail = '';
1216                 $startOpts = '';
1217
1218                 $noKeyOptions = [];
1219
1220                 foreach ( $options as $key => $option ) {
1221                         if ( is_numeric( $key ) ) {
1222                                 $noKeyOptions[$option] = true;
1223                         }
1224                 }
1225
1226                 $preLimitTail .= $this->makeGroupByWithHaving( $options );
1227
1228                 $preLimitTail .= $this->makeOrderBy( $options );
1229
1230                 if ( isset( $noKeyOptions['FOR UPDATE'] ) ) {
1231                         $postLimitTail .= ' FOR UPDATE';
1232                 }
1233
1234                 if ( isset( $noKeyOptions['LOCK IN SHARE MODE'] ) ) {
1235                         $postLimitTail .= ' LOCK IN SHARE MODE';
1236                 }
1237
1238                 if ( isset( $noKeyOptions['DISTINCT'] ) || isset( $noKeyOptions['DISTINCTROW'] ) ) {
1239                         $startOpts .= 'DISTINCT';
1240                 }
1241
1242                 # Various MySQL extensions
1243                 if ( isset( $noKeyOptions['STRAIGHT_JOIN'] ) ) {
1244                         $startOpts .= ' /*! STRAIGHT_JOIN */';
1245                 }
1246
1247                 if ( isset( $noKeyOptions['HIGH_PRIORITY'] ) ) {
1248                         $startOpts .= ' HIGH_PRIORITY';
1249                 }
1250
1251                 if ( isset( $noKeyOptions['SQL_BIG_RESULT'] ) ) {
1252                         $startOpts .= ' SQL_BIG_RESULT';
1253                 }
1254
1255                 if ( isset( $noKeyOptions['SQL_BUFFER_RESULT'] ) ) {
1256                         $startOpts .= ' SQL_BUFFER_RESULT';
1257                 }
1258
1259                 if ( isset( $noKeyOptions['SQL_SMALL_RESULT'] ) ) {
1260                         $startOpts .= ' SQL_SMALL_RESULT';
1261                 }
1262
1263                 if ( isset( $noKeyOptions['SQL_CALC_FOUND_ROWS'] ) ) {
1264                         $startOpts .= ' SQL_CALC_FOUND_ROWS';
1265                 }
1266
1267                 if ( isset( $noKeyOptions['SQL_CACHE'] ) ) {
1268                         $startOpts .= ' SQL_CACHE';
1269                 }
1270
1271                 if ( isset( $noKeyOptions['SQL_NO_CACHE'] ) ) {
1272                         $startOpts .= ' SQL_NO_CACHE';
1273                 }
1274
1275                 if ( isset( $options['USE INDEX'] ) && is_string( $options['USE INDEX'] ) ) {
1276                         $useIndex = $this->useIndexClause( $options['USE INDEX'] );
1277                 } else {
1278                         $useIndex = '';
1279                 }
1280                 if ( isset( $options['IGNORE INDEX'] ) && is_string( $options['IGNORE INDEX'] ) ) {
1281                         $ignoreIndex = $this->ignoreIndexClause( $options['IGNORE INDEX'] );
1282                 } else {
1283                         $ignoreIndex = '';
1284                 }
1285
1286                 return [ $startOpts, $useIndex, $preLimitTail, $postLimitTail, $ignoreIndex ];
1287         }
1288
1289         /**
1290          * Returns an optional GROUP BY with an optional HAVING
1291          *
1292          * @param array $options Associative array of options
1293          * @return string
1294          * @see Database::select()
1295          * @since 1.21
1296          */
1297         protected function makeGroupByWithHaving( $options ) {
1298                 $sql = '';
1299                 if ( isset( $options['GROUP BY'] ) ) {
1300                         $gb = is_array( $options['GROUP BY'] )
1301                                 ? implode( ',', $options['GROUP BY'] )
1302                                 : $options['GROUP BY'];
1303                         $sql .= ' GROUP BY ' . $gb;
1304                 }
1305                 if ( isset( $options['HAVING'] ) ) {
1306                         $having = is_array( $options['HAVING'] )
1307                                 ? $this->makeList( $options['HAVING'], self::LIST_AND )
1308                                 : $options['HAVING'];
1309                         $sql .= ' HAVING ' . $having;
1310                 }
1311
1312                 return $sql;
1313         }
1314
1315         /**
1316          * Returns an optional ORDER BY
1317          *
1318          * @param array $options Associative array of options
1319          * @return string
1320          * @see Database::select()
1321          * @since 1.21
1322          */
1323         protected function makeOrderBy( $options ) {
1324                 if ( isset( $options['ORDER BY'] ) ) {
1325                         $ob = is_array( $options['ORDER BY'] )
1326                                 ? implode( ',', $options['ORDER BY'] )
1327                                 : $options['ORDER BY'];
1328
1329                         return ' ORDER BY ' . $ob;
1330                 }
1331
1332                 return '';
1333         }
1334
1335         public function select( $table, $vars, $conds = '', $fname = __METHOD__,
1336                 $options = [], $join_conds = [] ) {
1337                 $sql = $this->selectSQLText( $table, $vars, $conds, $fname, $options, $join_conds );
1338
1339                 return $this->query( $sql, $fname );
1340         }
1341
1342         public function selectSQLText( $table, $vars, $conds = '', $fname = __METHOD__,
1343                 $options = [], $join_conds = []
1344         ) {
1345                 if ( is_array( $vars ) ) {
1346                         $vars = implode( ',', $this->fieldNamesWithAlias( $vars ) );
1347                 }
1348
1349                 $options = (array)$options;
1350                 $useIndexes = ( isset( $options['USE INDEX'] ) && is_array( $options['USE INDEX'] ) )
1351                         ? $options['USE INDEX']
1352                         : [];
1353                 $ignoreIndexes = (
1354                         isset( $options['IGNORE INDEX'] ) &&
1355                         is_array( $options['IGNORE INDEX'] )
1356                 )
1357                         ? $options['IGNORE INDEX']
1358                         : [];
1359
1360                 if ( is_array( $table ) ) {
1361                         $from = ' FROM ' .
1362                                 $this->tableNamesWithIndexClauseOrJOIN(
1363                                         $table, $useIndexes, $ignoreIndexes, $join_conds );
1364                 } elseif ( $table != '' ) {
1365                         if ( $table[0] == ' ' ) {
1366                                 $from = ' FROM ' . $table;
1367                         } else {
1368                                 $from = ' FROM ' .
1369                                         $this->tableNamesWithIndexClauseOrJOIN(
1370                                                 [ $table ], $useIndexes, $ignoreIndexes, [] );
1371                         }
1372                 } else {
1373                         $from = '';
1374                 }
1375
1376                 list( $startOpts, $useIndex, $preLimitTail, $postLimitTail, $ignoreIndex ) =
1377                         $this->makeSelectOptions( $options );
1378
1379                 if ( !empty( $conds ) ) {
1380                         if ( is_array( $conds ) ) {
1381                                 $conds = $this->makeList( $conds, self::LIST_AND );
1382                         }
1383                         $sql = "SELECT $startOpts $vars $from $useIndex $ignoreIndex " .
1384                                 "WHERE $conds $preLimitTail";
1385                 } else {
1386                         $sql = "SELECT $startOpts $vars $from $useIndex $ignoreIndex $preLimitTail";
1387                 }
1388
1389                 if ( isset( $options['LIMIT'] ) ) {
1390                         $sql = $this->limitResult( $sql, $options['LIMIT'],
1391                                 isset( $options['OFFSET'] ) ? $options['OFFSET'] : false );
1392                 }
1393                 $sql = "$sql $postLimitTail";
1394
1395                 if ( isset( $options['EXPLAIN'] ) ) {
1396                         $sql = 'EXPLAIN ' . $sql;
1397                 }
1398
1399                 return $sql;
1400         }
1401
1402         public function selectRow( $table, $vars, $conds, $fname = __METHOD__,
1403                 $options = [], $join_conds = []
1404         ) {
1405                 $options = (array)$options;
1406                 $options['LIMIT'] = 1;
1407                 $res = $this->select( $table, $vars, $conds, $fname, $options, $join_conds );
1408
1409                 if ( $res === false ) {
1410                         return false;
1411                 }
1412
1413                 if ( !$this->numRows( $res ) ) {
1414                         return false;
1415                 }
1416
1417                 $obj = $this->fetchObject( $res );
1418
1419                 return $obj;
1420         }
1421
1422         public function estimateRowCount(
1423                 $table, $vars = '*', $conds = '', $fname = __METHOD__, $options = []
1424         ) {
1425                 $rows = 0;
1426                 $res = $this->select( $table, [ 'rowcount' => 'COUNT(*)' ], $conds, $fname, $options );
1427
1428                 if ( $res ) {
1429                         $row = $this->fetchRow( $res );
1430                         $rows = ( isset( $row['rowcount'] ) ) ? (int)$row['rowcount'] : 0;
1431                 }
1432
1433                 return $rows;
1434         }
1435
1436         public function selectRowCount(
1437                 $tables, $vars = '*', $conds = '', $fname = __METHOD__, $options = [], $join_conds = []
1438         ) {
1439                 $rows = 0;
1440                 $sql = $this->selectSQLText( $tables, '1', $conds, $fname, $options, $join_conds );
1441                 // The identifier quotes is primarily for MSSQL.
1442                 $rowCountCol = $this->addIdentifierQuotes( "rowcount" );
1443                 $tableName = $this->addIdentifierQuotes( "tmp_count" );
1444                 $res = $this->query( "SELECT COUNT(*) AS $rowCountCol FROM ($sql) $tableName", $fname );
1445
1446                 if ( $res ) {
1447                         $row = $this->fetchRow( $res );
1448                         $rows = ( isset( $row['rowcount'] ) ) ? (int)$row['rowcount'] : 0;
1449                 }
1450
1451                 return $rows;
1452         }
1453
1454         /**
1455          * Removes most variables from an SQL query and replaces them with X or N for numbers.
1456          * It's only slightly flawed. Don't use for anything important.
1457          *
1458          * @param string $sql A SQL Query
1459          *
1460          * @return string
1461          */
1462         protected static function generalizeSQL( $sql ) {
1463                 # This does the same as the regexp below would do, but in such a way
1464                 # as to avoid crashing php on some large strings.
1465                 # $sql = preg_replace( "/'([^\\\\']|\\\\.)*'|\"([^\\\\\"]|\\\\.)*\"/", "'X'", $sql );
1466
1467                 $sql = str_replace( "\\\\", '', $sql );
1468                 $sql = str_replace( "\\'", '', $sql );
1469                 $sql = str_replace( "\\\"", '', $sql );
1470                 $sql = preg_replace( "/'.*'/s", "'X'", $sql );
1471                 $sql = preg_replace( '/".*"/s', "'X'", $sql );
1472
1473                 # All newlines, tabs, etc replaced by single space
1474                 $sql = preg_replace( '/\s+/', ' ', $sql );
1475
1476                 # All numbers => N,
1477                 # except the ones surrounded by characters, e.g. l10n
1478                 $sql = preg_replace( '/-?\d+(,-?\d+)+/s', 'N,...,N', $sql );
1479                 $sql = preg_replace( '/(?<![a-zA-Z])-?\d+(?![a-zA-Z])/s', 'N', $sql );
1480
1481                 return $sql;
1482         }
1483
1484         public function fieldExists( $table, $field, $fname = __METHOD__ ) {
1485                 $info = $this->fieldInfo( $table, $field );
1486
1487                 return (bool)$info;
1488         }
1489
1490         public function indexExists( $table, $index, $fname = __METHOD__ ) {
1491                 if ( !$this->tableExists( $table ) ) {
1492                         return null;
1493                 }
1494
1495                 $info = $this->indexInfo( $table, $index, $fname );
1496                 if ( is_null( $info ) ) {
1497                         return null;
1498                 } else {
1499                         return $info !== false;
1500                 }
1501         }
1502
1503         public function tableExists( $table, $fname = __METHOD__ ) {
1504                 $tableRaw = $this->tableName( $table, 'raw' );
1505                 if ( isset( $this->mSessionTempTables[$tableRaw] ) ) {
1506                         return true; // already known to exist
1507                 }
1508
1509                 $table = $this->tableName( $table );
1510                 $ignoreErrors = true;
1511                 $res = $this->query( "SELECT 1 FROM $table LIMIT 1", $fname, $ignoreErrors );
1512
1513                 return (bool)$res;
1514         }
1515
1516         public function indexUnique( $table, $index ) {
1517                 $indexInfo = $this->indexInfo( $table, $index );
1518
1519                 if ( !$indexInfo ) {
1520                         return null;
1521                 }
1522
1523                 return !$indexInfo[0]->Non_unique;
1524         }
1525
1526         /**
1527          * Helper for Database::insert().
1528          *
1529          * @param array $options
1530          * @return string
1531          */
1532         protected function makeInsertOptions( $options ) {
1533                 return implode( ' ', $options );
1534         }
1535
1536         public function insert( $table, $a, $fname = __METHOD__, $options = [] ) {
1537                 # No rows to insert, easy just return now
1538                 if ( !count( $a ) ) {
1539                         return true;
1540                 }
1541
1542                 $table = $this->tableName( $table );
1543
1544                 if ( !is_array( $options ) ) {
1545                         $options = [ $options ];
1546                 }
1547
1548                 $fh = null;
1549                 if ( isset( $options['fileHandle'] ) ) {
1550                         $fh = $options['fileHandle'];
1551                 }
1552                 $options = $this->makeInsertOptions( $options );
1553
1554                 if ( isset( $a[0] ) && is_array( $a[0] ) ) {
1555                         $multi = true;
1556                         $keys = array_keys( $a[0] );
1557                 } else {
1558                         $multi = false;
1559                         $keys = array_keys( $a );
1560                 }
1561
1562                 $sql = 'INSERT ' . $options .
1563                         " INTO $table (" . implode( ',', $keys ) . ') VALUES ';
1564
1565                 if ( $multi ) {
1566                         $first = true;
1567                         foreach ( $a as $row ) {
1568                                 if ( $first ) {
1569                                         $first = false;
1570                                 } else {
1571                                         $sql .= ',';
1572                                 }
1573                                 $sql .= '(' . $this->makeList( $row ) . ')';
1574                         }
1575                 } else {
1576                         $sql .= '(' . $this->makeList( $a ) . ')';
1577                 }
1578
1579                 if ( $fh !== null && false === fwrite( $fh, $sql ) ) {
1580                         return false;
1581                 } elseif ( $fh !== null ) {
1582                         return true;
1583                 }
1584
1585                 return (bool)$this->query( $sql, $fname );
1586         }
1587
1588         /**
1589          * Make UPDATE options array for Database::makeUpdateOptions
1590          *
1591          * @param array $options
1592          * @return array
1593          */
1594         protected function makeUpdateOptionsArray( $options ) {
1595                 if ( !is_array( $options ) ) {
1596                         $options = [ $options ];
1597                 }
1598
1599                 $opts = [];
1600
1601                 if ( in_array( 'IGNORE', $options ) ) {
1602                         $opts[] = 'IGNORE';
1603                 }
1604
1605                 return $opts;
1606         }
1607
1608         /**
1609          * Make UPDATE options for the Database::update function
1610          *
1611          * @param array $options The options passed to Database::update
1612          * @return string
1613          */
1614         protected function makeUpdateOptions( $options ) {
1615                 $opts = $this->makeUpdateOptionsArray( $options );
1616
1617                 return implode( ' ', $opts );
1618         }
1619
1620         public function update( $table, $values, $conds, $fname = __METHOD__, $options = [] ) {
1621                 $table = $this->tableName( $table );
1622                 $opts = $this->makeUpdateOptions( $options );
1623                 $sql = "UPDATE $opts $table SET " . $this->makeList( $values, self::LIST_SET );
1624
1625                 if ( $conds !== [] && $conds !== '*' ) {
1626                         $sql .= " WHERE " . $this->makeList( $conds, self::LIST_AND );
1627                 }
1628
1629                 return (bool)$this->query( $sql, $fname );
1630         }
1631
1632         public function makeList( $a, $mode = self::LIST_COMMA ) {
1633                 if ( !is_array( $a ) ) {
1634                         throw new DBUnexpectedError( $this, __METHOD__ . ' called with incorrect parameters' );
1635                 }
1636
1637                 $first = true;
1638                 $list = '';
1639
1640                 foreach ( $a as $field => $value ) {
1641                         if ( !$first ) {
1642                                 if ( $mode == self::LIST_AND ) {
1643                                         $list .= ' AND ';
1644                                 } elseif ( $mode == self::LIST_OR ) {
1645                                         $list .= ' OR ';
1646                                 } else {
1647                                         $list .= ',';
1648                                 }
1649                         } else {
1650                                 $first = false;
1651                         }
1652
1653                         if ( ( $mode == self::LIST_AND || $mode == self::LIST_OR ) && is_numeric( $field ) ) {
1654                                 $list .= "($value)";
1655                         } elseif ( $mode == self::LIST_SET && is_numeric( $field ) ) {
1656                                 $list .= "$value";
1657                         } elseif (
1658                                 ( $mode == self::LIST_AND || $mode == self::LIST_OR ) && is_array( $value )
1659                         ) {
1660                                 // Remove null from array to be handled separately if found
1661                                 $includeNull = false;
1662                                 foreach ( array_keys( $value, null, true ) as $nullKey ) {
1663                                         $includeNull = true;
1664                                         unset( $value[$nullKey] );
1665                                 }
1666                                 if ( count( $value ) == 0 && !$includeNull ) {
1667                                         throw new InvalidArgumentException(
1668                                                 __METHOD__ . ": empty input for field $field" );
1669                                 } elseif ( count( $value ) == 0 ) {
1670                                         // only check if $field is null
1671                                         $list .= "$field IS NULL";
1672                                 } else {
1673                                         // IN clause contains at least one valid element
1674                                         if ( $includeNull ) {
1675                                                 // Group subconditions to ensure correct precedence
1676                                                 $list .= '(';
1677                                         }
1678                                         if ( count( $value ) == 1 ) {
1679                                                 // Special-case single values, as IN isn't terribly efficient
1680                                                 // Don't necessarily assume the single key is 0; we don't
1681                                                 // enforce linear numeric ordering on other arrays here.
1682                                                 $value = array_values( $value )[0];
1683                                                 $list .= $field . " = " . $this->addQuotes( $value );
1684                                         } else {
1685                                                 $list .= $field . " IN (" . $this->makeList( $value ) . ") ";
1686                                         }
1687                                         // if null present in array, append IS NULL
1688                                         if ( $includeNull ) {
1689                                                 $list .= " OR $field IS NULL)";
1690                                         }
1691                                 }
1692                         } elseif ( $value === null ) {
1693                                 if ( $mode == self::LIST_AND || $mode == self::LIST_OR ) {
1694                                         $list .= "$field IS ";
1695                                 } elseif ( $mode == self::LIST_SET ) {
1696                                         $list .= "$field = ";
1697                                 }
1698                                 $list .= 'NULL';
1699                         } else {
1700                                 if (
1701                                         $mode == self::LIST_AND || $mode == self::LIST_OR || $mode == self::LIST_SET
1702                                 ) {
1703                                         $list .= "$field = ";
1704                                 }
1705                                 $list .= $mode == self::LIST_NAMES ? $value : $this->addQuotes( $value );
1706                         }
1707                 }
1708
1709                 return $list;
1710         }
1711
1712         public function makeWhereFrom2d( $data, $baseKey, $subKey ) {
1713                 $conds = [];
1714
1715                 foreach ( $data as $base => $sub ) {
1716                         if ( count( $sub ) ) {
1717                                 $conds[] = $this->makeList(
1718                                         [ $baseKey => $base, $subKey => array_keys( $sub ) ],
1719                                         self::LIST_AND );
1720                         }
1721                 }
1722
1723                 if ( $conds ) {
1724                         return $this->makeList( $conds, self::LIST_OR );
1725                 } else {
1726                         // Nothing to search for...
1727                         return false;
1728                 }
1729         }
1730
1731         public function aggregateValue( $valuedata, $valuename = 'value' ) {
1732                 return $valuename;
1733         }
1734
1735         public function bitNot( $field ) {
1736                 return "(~$field)";
1737         }
1738
1739         public function bitAnd( $fieldLeft, $fieldRight ) {
1740                 return "($fieldLeft & $fieldRight)";
1741         }
1742
1743         public function bitOr( $fieldLeft, $fieldRight ) {
1744                 return "($fieldLeft | $fieldRight)";
1745         }
1746
1747         public function buildConcat( $stringList ) {
1748                 return 'CONCAT(' . implode( ',', $stringList ) . ')';
1749         }
1750
1751         public function buildGroupConcatField(
1752                 $delim, $table, $field, $conds = '', $join_conds = []
1753         ) {
1754                 $fld = "GROUP_CONCAT($field SEPARATOR " . $this->addQuotes( $delim ) . ')';
1755
1756                 return '(' . $this->selectSQLText( $table, $fld, $conds, null, [], $join_conds ) . ')';
1757         }
1758
1759         public function buildStringCast( $field ) {
1760                 return $field;
1761         }
1762
1763         public function databasesAreIndependent() {
1764                 return false;
1765         }
1766
1767         public function selectDB( $db ) {
1768                 # Stub. Shouldn't cause serious problems if it's not overridden, but
1769                 # if your database engine supports a concept similar to MySQL's
1770                 # databases you may as well.
1771                 $this->mDBname = $db;
1772
1773                 return true;
1774         }
1775
1776         public function getDBname() {
1777                 return $this->mDBname;
1778         }
1779
1780         public function getServer() {
1781                 return $this->mServer;
1782         }
1783
1784         public function tableName( $name, $format = 'quoted' ) {
1785                 # Skip the entire process when we have a string quoted on both ends.
1786                 # Note that we check the end so that we will still quote any use of
1787                 # use of `database`.table. But won't break things if someone wants
1788                 # to query a database table with a dot in the name.
1789                 if ( $this->isQuotedIdentifier( $name ) ) {
1790                         return $name;
1791                 }
1792
1793                 # Lets test for any bits of text that should never show up in a table
1794                 # name. Basically anything like JOIN or ON which are actually part of
1795                 # SQL queries, but may end up inside of the table value to combine
1796                 # sql. Such as how the API is doing.
1797                 # Note that we use a whitespace test rather than a \b test to avoid
1798                 # any remote case where a word like on may be inside of a table name
1799                 # surrounded by symbols which may be considered word breaks.
1800                 if ( preg_match( '/(^|\s)(DISTINCT|JOIN|ON|AS)(\s|$)/i', $name ) !== 0 ) {
1801                         return $name;
1802                 }
1803
1804                 # Split database and table into proper variables.
1805                 list( $database, $schema, $prefix, $table ) = $this->qualifiedTableComponents( $name );
1806
1807                 # Quote $table and apply the prefix if not quoted.
1808                 # $tableName might be empty if this is called from Database::replaceVars()
1809                 $tableName = "{$prefix}{$table}";
1810                 if ( $format === 'quoted'
1811                         && !$this->isQuotedIdentifier( $tableName )
1812                         && $tableName !== ''
1813                 ) {
1814                         $tableName = $this->addIdentifierQuotes( $tableName );
1815                 }
1816
1817                 # Quote $schema and $database and merge them with the table name if needed
1818                 $tableName = $this->prependDatabaseOrSchema( $schema, $tableName, $format );
1819                 $tableName = $this->prependDatabaseOrSchema( $database, $tableName, $format );
1820
1821                 return $tableName;
1822         }
1823
1824         /**
1825          * @param string $name Table name
1826          * @return array (DB name, schema name, table prefix, table name)
1827          */
1828         protected function qualifiedTableComponents( $name ) {
1829                 # We reverse the explode so that database.table and table both output the correct table.
1830                 $dbDetails = explode( '.', $name, 3 );
1831                 if ( count( $dbDetails ) == 3 ) {
1832                         list( $database, $schema, $table ) = $dbDetails;
1833                         # We don't want any prefix added in this case
1834                         $prefix = '';
1835                 } elseif ( count( $dbDetails ) == 2 ) {
1836                         list( $database, $table ) = $dbDetails;
1837                         # We don't want any prefix added in this case
1838                         $prefix = '';
1839                         # In dbs that support it, $database may actually be the schema
1840                         # but that doesn't affect any of the functionality here
1841                         $schema = '';
1842                 } else {
1843                         list( $table ) = $dbDetails;
1844                         if ( isset( $this->tableAliases[$table] ) ) {
1845                                 $database = $this->tableAliases[$table]['dbname'];
1846                                 $schema = is_string( $this->tableAliases[$table]['schema'] )
1847                                         ? $this->tableAliases[$table]['schema']
1848                                         : $this->mSchema;
1849                                 $prefix = is_string( $this->tableAliases[$table]['prefix'] )
1850                                         ? $this->tableAliases[$table]['prefix']
1851                                         : $this->mTablePrefix;
1852                         } else {
1853                                 $database = '';
1854                                 $schema = $this->mSchema; # Default schema
1855                                 $prefix = $this->mTablePrefix; # Default prefix
1856                         }
1857                 }
1858
1859                 return [ $database, $schema, $prefix, $table ];
1860         }
1861
1862         /**
1863          * @param string|null $namespace Database or schema
1864          * @param string $relation Name of table, view, sequence, etc...
1865          * @param string $format One of (raw, quoted)
1866          * @return string Relation name with quoted and merged $namespace as needed
1867          */
1868         private function prependDatabaseOrSchema( $namespace, $relation, $format ) {
1869                 if ( strlen( $namespace ) ) {
1870                         if ( $format === 'quoted' && !$this->isQuotedIdentifier( $namespace ) ) {
1871                                 $namespace = $this->addIdentifierQuotes( $namespace );
1872                         }
1873                         $relation = $namespace . '.' . $relation;
1874                 }
1875
1876                 return $relation;
1877         }
1878
1879         public function tableNames() {
1880                 $inArray = func_get_args();
1881                 $retVal = [];
1882
1883                 foreach ( $inArray as $name ) {
1884                         $retVal[$name] = $this->tableName( $name );
1885                 }
1886
1887                 return $retVal;
1888         }
1889
1890         public function tableNamesN() {
1891                 $inArray = func_get_args();
1892                 $retVal = [];
1893
1894                 foreach ( $inArray as $name ) {
1895                         $retVal[] = $this->tableName( $name );
1896                 }
1897
1898                 return $retVal;
1899         }
1900
1901         /**
1902          * Get an aliased table name
1903          * e.g. tableName AS newTableName
1904          *
1905          * @param string $name Table name, see tableName()
1906          * @param string|bool $alias Alias (optional)
1907          * @return string SQL name for aliased table. Will not alias a table to its own name
1908          */
1909         protected function tableNameWithAlias( $name, $alias = false ) {
1910                 if ( !$alias || $alias == $name ) {
1911                         return $this->tableName( $name );
1912                 } else {
1913                         return $this->tableName( $name ) . ' ' . $this->addIdentifierQuotes( $alias );
1914                 }
1915         }
1916
1917         /**
1918          * Gets an array of aliased table names
1919          *
1920          * @param array $tables [ [alias] => table ]
1921          * @return string[] See tableNameWithAlias()
1922          */
1923         protected function tableNamesWithAlias( $tables ) {
1924                 $retval = [];
1925                 foreach ( $tables as $alias => $table ) {
1926                         if ( is_numeric( $alias ) ) {
1927                                 $alias = $table;
1928                         }
1929                         $retval[] = $this->tableNameWithAlias( $table, $alias );
1930                 }
1931
1932                 return $retval;
1933         }
1934
1935         /**
1936          * Get an aliased field name
1937          * e.g. fieldName AS newFieldName
1938          *
1939          * @param string $name Field name
1940          * @param string|bool $alias Alias (optional)
1941          * @return string SQL name for aliased field. Will not alias a field to its own name
1942          */
1943         protected function fieldNameWithAlias( $name, $alias = false ) {
1944                 if ( !$alias || (string)$alias === (string)$name ) {
1945                         return $name;
1946                 } else {
1947                         return $name . ' AS ' . $this->addIdentifierQuotes( $alias ); // PostgreSQL needs AS
1948                 }
1949         }
1950
1951         /**
1952          * Gets an array of aliased field names
1953          *
1954          * @param array $fields [ [alias] => field ]
1955          * @return string[] See fieldNameWithAlias()
1956          */
1957         protected function fieldNamesWithAlias( $fields ) {
1958                 $retval = [];
1959                 foreach ( $fields as $alias => $field ) {
1960                         if ( is_numeric( $alias ) ) {
1961                                 $alias = $field;
1962                         }
1963                         $retval[] = $this->fieldNameWithAlias( $field, $alias );
1964                 }
1965
1966                 return $retval;
1967         }
1968
1969         /**
1970          * Get the aliased table name clause for a FROM clause
1971          * which might have a JOIN and/or USE INDEX or IGNORE INDEX clause
1972          *
1973          * @param array $tables ( [alias] => table )
1974          * @param array $use_index Same as for select()
1975          * @param array $ignore_index Same as for select()
1976          * @param array $join_conds Same as for select()
1977          * @return string
1978          */
1979         protected function tableNamesWithIndexClauseOrJOIN(
1980                 $tables, $use_index = [], $ignore_index = [], $join_conds = []
1981         ) {
1982                 $ret = [];
1983                 $retJOIN = [];
1984                 $use_index = (array)$use_index;
1985                 $ignore_index = (array)$ignore_index;
1986                 $join_conds = (array)$join_conds;
1987
1988                 foreach ( $tables as $alias => $table ) {
1989                         if ( !is_string( $alias ) ) {
1990                                 // No alias? Set it equal to the table name
1991                                 $alias = $table;
1992                         }
1993                         // Is there a JOIN clause for this table?
1994                         if ( isset( $join_conds[$alias] ) ) {
1995                                 list( $joinType, $conds ) = $join_conds[$alias];
1996                                 $tableClause = $joinType;
1997                                 $tableClause .= ' ' . $this->tableNameWithAlias( $table, $alias );
1998                                 if ( isset( $use_index[$alias] ) ) { // has USE INDEX?
1999                                         $use = $this->useIndexClause( implode( ',', (array)$use_index[$alias] ) );
2000                                         if ( $use != '' ) {
2001                                                 $tableClause .= ' ' . $use;
2002                                         }
2003                                 }
2004                                 if ( isset( $ignore_index[$alias] ) ) { // has IGNORE INDEX?
2005                                         $ignore = $this->ignoreIndexClause(
2006                                                 implode( ',', (array)$ignore_index[$alias] ) );
2007                                         if ( $ignore != '' ) {
2008                                                 $tableClause .= ' ' . $ignore;
2009                                         }
2010                                 }
2011                                 $on = $this->makeList( (array)$conds, self::LIST_AND );
2012                                 if ( $on != '' ) {
2013                                         $tableClause .= ' ON (' . $on . ')';
2014                                 }
2015
2016                                 $retJOIN[] = $tableClause;
2017                         } elseif ( isset( $use_index[$alias] ) ) {
2018                                 // Is there an INDEX clause for this table?
2019                                 $tableClause = $this->tableNameWithAlias( $table, $alias );
2020                                 $tableClause .= ' ' . $this->useIndexClause(
2021                                                 implode( ',', (array)$use_index[$alias] )
2022                                         );
2023
2024                                 $ret[] = $tableClause;
2025                         } elseif ( isset( $ignore_index[$alias] ) ) {
2026                                 // Is there an INDEX clause for this table?
2027                                 $tableClause = $this->tableNameWithAlias( $table, $alias );
2028                                 $tableClause .= ' ' . $this->ignoreIndexClause(
2029                                                 implode( ',', (array)$ignore_index[$alias] )
2030                                         );
2031
2032                                 $ret[] = $tableClause;
2033                         } else {
2034                                 $tableClause = $this->tableNameWithAlias( $table, $alias );
2035
2036                                 $ret[] = $tableClause;
2037                         }
2038                 }
2039
2040                 // We can't separate explicit JOIN clauses with ',', use ' ' for those
2041                 $implicitJoins = !empty( $ret ) ? implode( ',', $ret ) : "";
2042                 $explicitJoins = !empty( $retJOIN ) ? implode( ' ', $retJOIN ) : "";
2043
2044                 // Compile our final table clause
2045                 return implode( ' ', [ $implicitJoins, $explicitJoins ] );
2046         }
2047
2048         /**
2049          * Allows for index remapping in queries where this is not consistent across DBMS
2050          *
2051          * @param string $index
2052          * @return string
2053          */
2054         protected function indexName( $index ) {
2055                 return $index;
2056         }
2057
2058         public function addQuotes( $s ) {
2059                 if ( $s instanceof Blob ) {
2060                         $s = $s->fetch();
2061                 }
2062                 if ( $s === null ) {
2063                         return 'NULL';
2064                 } elseif ( is_bool( $s ) ) {
2065                         return (int)$s;
2066                 } else {
2067                         # This will also quote numeric values. This should be harmless,
2068                         # and protects against weird problems that occur when they really
2069                         # _are_ strings such as article titles and string->number->string
2070                         # conversion is not 1:1.
2071                         return "'" . $this->strencode( $s ) . "'";
2072                 }
2073         }
2074
2075         /**
2076          * Quotes an identifier using `backticks` or "double quotes" depending on the database type.
2077          * MySQL uses `backticks` while basically everything else uses double quotes.
2078          * Since MySQL is the odd one out here the double quotes are our generic
2079          * and we implement backticks in DatabaseMysql.
2080          *
2081          * @param string $s
2082          * @return string
2083          */
2084         public function addIdentifierQuotes( $s ) {
2085                 return '"' . str_replace( '"', '""', $s ) . '"';
2086         }
2087
2088         /**
2089          * Returns if the given identifier looks quoted or not according to
2090          * the database convention for quoting identifiers .
2091          *
2092          * @note Do not use this to determine if untrusted input is safe.
2093          *   A malicious user can trick this function.
2094          * @param string $name
2095          * @return bool
2096          */
2097         public function isQuotedIdentifier( $name ) {
2098                 return $name[0] == '"' && substr( $name, -1, 1 ) == '"';
2099         }
2100
2101         /**
2102          * @param string $s
2103          * @return string
2104          */
2105         protected function escapeLikeInternal( $s, $escapeChar = '`' ) {
2106                 return str_replace( [ $escapeChar, '%', '_' ],
2107                         [ "{$escapeChar}{$escapeChar}", "{$escapeChar}%", "{$escapeChar}_" ],
2108                         $s );
2109         }
2110
2111         public function buildLike() {
2112                 $params = func_get_args();
2113
2114                 if ( count( $params ) > 0 && is_array( $params[0] ) ) {
2115                         $params = $params[0];
2116                 }
2117
2118                 $s = '';
2119
2120                 // We use ` instead of \ as the default LIKE escape character, since addQuotes()
2121                 // may escape backslashes, creating problems of double escaping. The `
2122                 // character has good cross-DBMS compatibility, avoiding special operators
2123                 // in MS SQL like ^ and %
2124                 $escapeChar = '`';
2125
2126                 foreach ( $params as $value ) {
2127                         if ( $value instanceof LikeMatch ) {
2128                                 $s .= $value->toString();
2129                         } else {
2130                                 $s .= $this->escapeLikeInternal( $value, $escapeChar );
2131                         }
2132                 }
2133
2134                 return ' LIKE ' . $this->addQuotes( $s ) . ' ESCAPE ' . $this->addQuotes( $escapeChar ) . ' ';
2135         }
2136
2137         public function anyChar() {
2138                 return new LikeMatch( '_' );
2139         }
2140
2141         public function anyString() {
2142                 return new LikeMatch( '%' );
2143         }
2144
2145         public function nextSequenceValue( $seqName ) {
2146                 return null;
2147         }
2148
2149         /**
2150          * USE INDEX clause. Unlikely to be useful for anything but MySQL. This
2151          * is only needed because a) MySQL must be as efficient as possible due to
2152          * its use on Wikipedia, and b) MySQL 4.0 is kind of dumb sometimes about
2153          * which index to pick. Anyway, other databases might have different
2154          * indexes on a given table. So don't bother overriding this unless you're
2155          * MySQL.
2156          * @param string $index
2157          * @return string
2158          */
2159         public function useIndexClause( $index ) {
2160                 return '';
2161         }
2162
2163         /**
2164          * IGNORE INDEX clause. Unlikely to be useful for anything but MySQL. This
2165          * is only needed because a) MySQL must be as efficient as possible due to
2166          * its use on Wikipedia, and b) MySQL 4.0 is kind of dumb sometimes about
2167          * which index to pick. Anyway, other databases might have different
2168          * indexes on a given table. So don't bother overriding this unless you're
2169          * MySQL.
2170          * @param string $index
2171          * @return string
2172          */
2173         public function ignoreIndexClause( $index ) {
2174                 return '';
2175         }
2176
2177         public function replace( $table, $uniqueIndexes, $rows, $fname = __METHOD__ ) {
2178                 $quotedTable = $this->tableName( $table );
2179
2180                 if ( count( $rows ) == 0 ) {
2181                         return;
2182                 }
2183
2184                 # Single row case
2185                 if ( !is_array( reset( $rows ) ) ) {
2186                         $rows = [ $rows ];
2187                 }
2188
2189                 // @FXIME: this is not atomic, but a trx would break affectedRows()
2190                 foreach ( $rows as $row ) {
2191                         # Delete rows which collide
2192                         if ( $uniqueIndexes ) {
2193                                 $sql = "DELETE FROM $quotedTable WHERE ";
2194                                 $first = true;
2195                                 foreach ( $uniqueIndexes as $index ) {
2196                                         if ( $first ) {
2197                                                 $first = false;
2198                                                 $sql .= '( ';
2199                                         } else {
2200                                                 $sql .= ' ) OR ( ';
2201                                         }
2202                                         if ( is_array( $index ) ) {
2203                                                 $first2 = true;
2204                                                 foreach ( $index as $col ) {
2205                                                         if ( $first2 ) {
2206                                                                 $first2 = false;
2207                                                         } else {
2208                                                                 $sql .= ' AND ';
2209                                                         }
2210                                                         $sql .= $col . '=' . $this->addQuotes( $row[$col] );
2211                                                 }
2212                                         } else {
2213                                                 $sql .= $index . '=' . $this->addQuotes( $row[$index] );
2214                                         }
2215                                 }
2216                                 $sql .= ' )';
2217                                 $this->query( $sql, $fname );
2218                         }
2219
2220                         # Now insert the row
2221                         $this->insert( $table, $row, $fname );
2222                 }
2223         }
2224
2225         /**
2226          * REPLACE query wrapper for MySQL and SQLite, which have a native REPLACE
2227          * statement.
2228          *
2229          * @param string $table Table name
2230          * @param array|string $rows Row(s) to insert
2231          * @param string $fname Caller function name
2232          *
2233          * @return ResultWrapper
2234          */
2235         protected function nativeReplace( $table, $rows, $fname ) {
2236                 $table = $this->tableName( $table );
2237
2238                 # Single row case
2239                 if ( !is_array( reset( $rows ) ) ) {
2240                         $rows = [ $rows ];
2241                 }
2242
2243                 $sql = "REPLACE INTO $table (" . implode( ',', array_keys( $rows[0] ) ) . ') VALUES ';
2244                 $first = true;
2245
2246                 foreach ( $rows as $row ) {
2247                         if ( $first ) {
2248                                 $first = false;
2249                         } else {
2250                                 $sql .= ',';
2251                         }
2252
2253                         $sql .= '(' . $this->makeList( $row ) . ')';
2254                 }
2255
2256                 return $this->query( $sql, $fname );
2257         }
2258
2259         public function upsert( $table, array $rows, array $uniqueIndexes, array $set,
2260                 $fname = __METHOD__
2261         ) {
2262                 if ( !count( $rows ) ) {
2263                         return true; // nothing to do
2264                 }
2265
2266                 if ( !is_array( reset( $rows ) ) ) {
2267                         $rows = [ $rows ];
2268                 }
2269
2270                 if ( count( $uniqueIndexes ) ) {
2271                         $clauses = []; // list WHERE clauses that each identify a single row
2272                         foreach ( $rows as $row ) {
2273                                 foreach ( $uniqueIndexes as $index ) {
2274                                         $index = is_array( $index ) ? $index : [ $index ]; // columns
2275                                         $rowKey = []; // unique key to this row
2276                                         foreach ( $index as $column ) {
2277                                                 $rowKey[$column] = $row[$column];
2278                                         }
2279                                         $clauses[] = $this->makeList( $rowKey, self::LIST_AND );
2280                                 }
2281                         }
2282                         $where = [ $this->makeList( $clauses, self::LIST_OR ) ];
2283                 } else {
2284                         $where = false;
2285                 }
2286
2287                 $useTrx = !$this->mTrxLevel;
2288                 if ( $useTrx ) {
2289                         $this->begin( $fname, self::TRANSACTION_INTERNAL );
2290                 }
2291                 try {
2292                         # Update any existing conflicting row(s)
2293                         if ( $where !== false ) {
2294                                 $ok = $this->update( $table, $set, $where, $fname );
2295                         } else {
2296                                 $ok = true;
2297                         }
2298                         # Now insert any non-conflicting row(s)
2299                         $ok = $this->insert( $table, $rows, $fname, [ 'IGNORE' ] ) && $ok;
2300                 } catch ( Exception $e ) {
2301                         if ( $useTrx ) {
2302                                 $this->rollback( $fname, self::FLUSHING_INTERNAL );
2303                         }
2304                         throw $e;
2305                 }
2306                 if ( $useTrx ) {
2307                         $this->commit( $fname, self::FLUSHING_INTERNAL );
2308                 }
2309
2310                 return $ok;
2311         }
2312
2313         public function deleteJoin( $delTable, $joinTable, $delVar, $joinVar, $conds,
2314                 $fname = __METHOD__
2315         ) {
2316                 if ( !$conds ) {
2317                         throw new DBUnexpectedError( $this, __METHOD__ . ' called with empty $conds' );
2318                 }
2319
2320                 $delTable = $this->tableName( $delTable );
2321                 $joinTable = $this->tableName( $joinTable );
2322                 $sql = "DELETE FROM $delTable WHERE $delVar IN (SELECT $joinVar FROM $joinTable ";
2323                 if ( $conds != '*' ) {
2324                         $sql .= 'WHERE ' . $this->makeList( $conds, self::LIST_AND );
2325                 }
2326                 $sql .= ')';
2327
2328                 $this->query( $sql, $fname );
2329         }
2330
2331         public function textFieldSize( $table, $field ) {
2332                 $table = $this->tableName( $table );
2333                 $sql = "SHOW COLUMNS FROM $table LIKE \"$field\";";
2334                 $res = $this->query( $sql, __METHOD__ );
2335                 $row = $this->fetchObject( $res );
2336
2337                 $m = [];
2338
2339                 if ( preg_match( '/\((.*)\)/', $row->Type, $m ) ) {
2340                         $size = $m[1];
2341                 } else {
2342                         $size = -1;
2343                 }
2344
2345                 return $size;
2346         }
2347
2348         public function delete( $table, $conds, $fname = __METHOD__ ) {
2349                 if ( !$conds ) {
2350                         throw new DBUnexpectedError( $this, __METHOD__ . ' called with no conditions' );
2351                 }
2352
2353                 $table = $this->tableName( $table );
2354                 $sql = "DELETE FROM $table";
2355
2356                 if ( $conds != '*' ) {
2357                         if ( is_array( $conds ) ) {
2358                                 $conds = $this->makeList( $conds, self::LIST_AND );
2359                         }
2360                         $sql .= ' WHERE ' . $conds;
2361                 }
2362
2363                 return $this->query( $sql, $fname );
2364         }
2365
2366         public function insertSelect(
2367                 $destTable, $srcTable, $varMap, $conds,
2368                 $fname = __METHOD__, $insertOptions = [], $selectOptions = [], $selectJoinConds = []
2369         ) {
2370                 if ( $this->cliMode ) {
2371                         // For massive migrations with downtime, we don't want to select everything
2372                         // into memory and OOM, so do all this native on the server side if possible.
2373                         return $this->nativeInsertSelect(
2374                                 $destTable,
2375                                 $srcTable,
2376                                 $varMap,
2377                                 $conds,
2378                                 $fname,
2379                                 $insertOptions,
2380                                 $selectOptions,
2381                                 $selectJoinConds
2382                         );
2383                 }
2384
2385                 // For web requests, do a locking SELECT and then INSERT. This puts the SELECT burden
2386                 // on only the master (without needing row-based-replication). It also makes it easy to
2387                 // know how big the INSERT is going to be.
2388                 $fields = [];
2389                 foreach ( $varMap as $dstColumn => $sourceColumnOrSql ) {
2390                         $fields[] = $this->fieldNameWithAlias( $sourceColumnOrSql, $dstColumn );
2391                 }
2392                 $selectOptions[] = 'FOR UPDATE';
2393                 $res = $this->select(
2394                         $srcTable, implode( ',', $fields ), $conds, $fname, $selectOptions, $selectJoinConds
2395                 );
2396                 if ( !$res ) {
2397                         return false;
2398                 }
2399
2400                 $rows = [];
2401                 foreach ( $res as $row ) {
2402                         $rows[] = (array)$row;
2403                 }
2404
2405                 return $this->insert( $destTable, $rows, $fname, $insertOptions );
2406         }
2407
2408         /**
2409          * Native server-side implementation of insertSelect() for situations where
2410          * we don't want to select everything into memory
2411          *
2412          * @see IDatabase::insertSelect()
2413          */
2414         protected function nativeInsertSelect( $destTable, $srcTable, $varMap, $conds,
2415                 $fname = __METHOD__,
2416                 $insertOptions = [], $selectOptions = [], $selectJoinConds = []
2417         ) {
2418                 $destTable = $this->tableName( $destTable );
2419
2420                 if ( !is_array( $insertOptions ) ) {
2421                         $insertOptions = [ $insertOptions ];
2422                 }
2423
2424                 $insertOptions = $this->makeInsertOptions( $insertOptions );
2425
2426                 $selectSql = $this->selectSQLText(
2427                         $srcTable,
2428                         array_values( $varMap ),
2429                         $conds,
2430                         $fname,
2431                         $selectOptions,
2432                         $selectJoinConds
2433                 );
2434
2435                 $sql = "INSERT $insertOptions" .
2436                         " INTO $destTable (" . implode( ',', array_keys( $varMap ) ) . ') ' .
2437                         $selectSql;
2438
2439                 return $this->query( $sql, $fname );
2440         }
2441
2442         /**
2443          * Construct a LIMIT query with optional offset. This is used for query
2444          * pages. The SQL should be adjusted so that only the first $limit rows
2445          * are returned. If $offset is provided as well, then the first $offset
2446          * rows should be discarded, and the next $limit rows should be returned.
2447          * If the result of the query is not ordered, then the rows to be returned
2448          * are theoretically arbitrary.
2449          *
2450          * $sql is expected to be a SELECT, if that makes a difference.
2451          *
2452          * The version provided by default works in MySQL and SQLite. It will very
2453          * likely need to be overridden for most other DBMSes.
2454          *
2455          * @param string $sql SQL query we will append the limit too
2456          * @param int $limit The SQL limit
2457          * @param int|bool $offset The SQL offset (default false)
2458          * @throws DBUnexpectedError
2459          * @return string
2460          */
2461         public function limitResult( $sql, $limit, $offset = false ) {
2462                 if ( !is_numeric( $limit ) ) {
2463                         throw new DBUnexpectedError( $this,
2464                                 "Invalid non-numeric limit passed to limitResult()\n" );
2465                 }
2466
2467                 return "$sql LIMIT "
2468                 . ( ( is_numeric( $offset ) && $offset != 0 ) ? "{$offset}," : "" )
2469                 . "{$limit} ";
2470         }
2471
2472         public function unionSupportsOrderAndLimit() {
2473                 return true; // True for almost every DB supported
2474         }
2475
2476         public function unionQueries( $sqls, $all ) {
2477                 $glue = $all ? ') UNION ALL (' : ') UNION (';
2478
2479                 return '(' . implode( $glue, $sqls ) . ')';
2480         }
2481
2482         public function conditional( $cond, $trueVal, $falseVal ) {
2483                 if ( is_array( $cond ) ) {
2484                         $cond = $this->makeList( $cond, self::LIST_AND );
2485                 }
2486
2487                 return " (CASE WHEN $cond THEN $trueVal ELSE $falseVal END) ";
2488         }
2489
2490         public function strreplace( $orig, $old, $new ) {
2491                 return "REPLACE({$orig}, {$old}, {$new})";
2492         }
2493
2494         public function getServerUptime() {
2495                 return 0;
2496         }
2497
2498         public function wasDeadlock() {
2499                 return false;
2500         }
2501
2502         public function wasLockTimeout() {
2503                 return false;
2504         }
2505
2506         public function wasErrorReissuable() {
2507                 return false;
2508         }
2509
2510         public function wasReadOnlyError() {
2511                 return false;
2512         }
2513
2514         /**
2515          * Do not use this method outside of Database/DBError classes
2516          *
2517          * @param integer|string $errno
2518          * @return bool Whether the given query error was a connection drop
2519          */
2520         public function wasConnectionError( $errno ) {
2521                 return false;
2522         }
2523
2524         public function deadlockLoop() {
2525                 $args = func_get_args();
2526                 $function = array_shift( $args );
2527                 $tries = self::DEADLOCK_TRIES;
2528
2529                 $this->begin( __METHOD__ );
2530
2531                 $retVal = null;
2532                 /** @var Exception $e */
2533                 $e = null;
2534                 do {
2535                         try {
2536                                 $retVal = call_user_func_array( $function, $args );
2537                                 break;
2538                         } catch ( DBQueryError $e ) {
2539                                 if ( $this->wasDeadlock() ) {
2540                                         // Retry after a randomized delay
2541                                         usleep( mt_rand( self::DEADLOCK_DELAY_MIN, self::DEADLOCK_DELAY_MAX ) );
2542                                 } else {
2543                                         // Throw the error back up
2544                                         throw $e;
2545                                 }
2546                         }
2547                 } while ( --$tries > 0 );
2548
2549                 if ( $tries <= 0 ) {
2550                         // Too many deadlocks; give up
2551                         $this->rollback( __METHOD__ );
2552                         throw $e;
2553                 } else {
2554                         $this->commit( __METHOD__ );
2555
2556                         return $retVal;
2557                 }
2558         }
2559
2560         public function masterPosWait( DBMasterPos $pos, $timeout ) {
2561                 # Real waits are implemented in the subclass.
2562                 return 0;
2563         }
2564
2565         public function getReplicaPos() {
2566                 # Stub
2567                 return false;
2568         }
2569
2570         public function getMasterPos() {
2571                 # Stub
2572                 return false;
2573         }
2574
2575         public function serverIsReadOnly() {
2576                 return false;
2577         }
2578
2579         final public function onTransactionResolution( callable $callback, $fname = __METHOD__ ) {
2580                 if ( !$this->mTrxLevel ) {
2581                         throw new DBUnexpectedError( $this, "No transaction is active." );
2582                 }
2583                 $this->mTrxEndCallbacks[] = [ $callback, $fname ];
2584         }
2585
2586         final public function onTransactionIdle( callable $callback, $fname = __METHOD__ ) {
2587                 $this->mTrxIdleCallbacks[] = [ $callback, $fname ];
2588                 if ( !$this->mTrxLevel ) {
2589                         $this->runOnTransactionIdleCallbacks( self::TRIGGER_IDLE );
2590                 }
2591         }
2592
2593         final public function onTransactionPreCommitOrIdle( callable $callback, $fname = __METHOD__ ) {
2594                 if ( $this->mTrxLevel ) {
2595                         $this->mTrxPreCommitCallbacks[] = [ $callback, $fname ];
2596                 } else {
2597                         // If no transaction is active, then make one for this callback
2598                         $this->startAtomic( __METHOD__ );
2599                         try {
2600                                 call_user_func( $callback );
2601                                 $this->endAtomic( __METHOD__ );
2602                         } catch ( Exception $e ) {
2603                                 $this->rollback( __METHOD__, self::FLUSHING_INTERNAL );
2604                                 throw $e;
2605                         }
2606                 }
2607         }
2608
2609         final public function setTransactionListener( $name, callable $callback = null ) {
2610                 if ( $callback ) {
2611                         $this->mTrxRecurringCallbacks[$name] = $callback;
2612                 } else {
2613                         unset( $this->mTrxRecurringCallbacks[$name] );
2614                 }
2615         }
2616
2617         /**
2618          * Whether to disable running of post-COMMIT/ROLLBACK callbacks
2619          *
2620          * This method should not be used outside of Database/LoadBalancer
2621          *
2622          * @param bool $suppress
2623          * @since 1.28
2624          */
2625         final public function setTrxEndCallbackSuppression( $suppress ) {
2626                 $this->mTrxEndCallbacksSuppressed = $suppress;
2627         }
2628
2629         /**
2630          * Actually run and consume any "on transaction idle/resolution" callbacks.
2631          *
2632          * This method should not be used outside of Database/LoadBalancer
2633          *
2634          * @param integer $trigger IDatabase::TRIGGER_* constant
2635          * @since 1.20
2636          * @throws Exception
2637          */
2638         public function runOnTransactionIdleCallbacks( $trigger ) {
2639                 if ( $this->mTrxEndCallbacksSuppressed ) {
2640                         return;
2641                 }
2642
2643                 $autoTrx = $this->getFlag( self::DBO_TRX ); // automatic begin() enabled?
2644                 /** @var Exception $e */
2645                 $e = null; // first exception
2646                 do { // callbacks may add callbacks :)
2647                         $callbacks = array_merge(
2648                                 $this->mTrxIdleCallbacks,
2649                                 $this->mTrxEndCallbacks // include "transaction resolution" callbacks
2650                         );
2651                         $this->mTrxIdleCallbacks = []; // consumed (and recursion guard)
2652                         $this->mTrxEndCallbacks = []; // consumed (recursion guard)
2653                         foreach ( $callbacks as $callback ) {
2654                                 try {
2655                                         list( $phpCallback ) = $callback;
2656                                         $this->clearFlag( self::DBO_TRX ); // make each query its own transaction
2657                                         call_user_func_array( $phpCallback, [ $trigger ] );
2658                                         if ( $autoTrx ) {
2659                                                 $this->setFlag( self::DBO_TRX ); // restore automatic begin()
2660                                         } else {
2661                                                 $this->clearFlag( self::DBO_TRX ); // restore auto-commit
2662                                         }
2663                                 } catch ( Exception $ex ) {
2664                                         call_user_func( $this->errorLogger, $ex );
2665                                         $e = $e ?: $ex;
2666                                         // Some callbacks may use startAtomic/endAtomic, so make sure
2667                                         // their transactions are ended so other callbacks don't fail
2668                                         if ( $this->trxLevel() ) {
2669                                                 $this->rollback( __METHOD__, self::FLUSHING_INTERNAL );
2670                                         }
2671                                 }
2672                         }
2673                 } while ( count( $this->mTrxIdleCallbacks ) );
2674
2675                 if ( $e instanceof Exception ) {
2676                         throw $e; // re-throw any first exception
2677                 }
2678         }
2679
2680         /**
2681          * Actually run and consume any "on transaction pre-commit" callbacks.
2682          *
2683          * This method should not be used outside of Database/LoadBalancer
2684          *
2685          * @since 1.22
2686          * @throws Exception
2687          */
2688         public function runOnTransactionPreCommitCallbacks() {
2689                 $e = null; // first exception
2690                 do { // callbacks may add callbacks :)
2691                         $callbacks = $this->mTrxPreCommitCallbacks;
2692                         $this->mTrxPreCommitCallbacks = []; // consumed (and recursion guard)
2693                         foreach ( $callbacks as $callback ) {
2694                                 try {
2695                                         list( $phpCallback ) = $callback;
2696                                         call_user_func( $phpCallback );
2697                                 } catch ( Exception $ex ) {
2698                                         call_user_func( $this->errorLogger, $ex );
2699                                         $e = $e ?: $ex;
2700                                 }
2701                         }
2702                 } while ( count( $this->mTrxPreCommitCallbacks ) );
2703
2704                 if ( $e instanceof Exception ) {
2705                         throw $e; // re-throw any first exception
2706                 }
2707         }
2708
2709         /**
2710          * Actually run any "transaction listener" callbacks.
2711          *
2712          * This method should not be used outside of Database/LoadBalancer
2713          *
2714          * @param integer $trigger IDatabase::TRIGGER_* constant
2715          * @throws Exception
2716          * @since 1.20
2717          */
2718         public function runTransactionListenerCallbacks( $trigger ) {
2719                 if ( $this->mTrxEndCallbacksSuppressed ) {
2720                         return;
2721                 }
2722
2723                 /** @var Exception $e */
2724                 $e = null; // first exception
2725
2726                 foreach ( $this->mTrxRecurringCallbacks as $phpCallback ) {
2727                         try {
2728                                 $phpCallback( $trigger, $this );
2729                         } catch ( Exception $ex ) {
2730                                 call_user_func( $this->errorLogger, $ex );
2731                                 $e = $e ?: $ex;
2732                         }
2733                 }
2734
2735                 if ( $e instanceof Exception ) {
2736                         throw $e; // re-throw any first exception
2737                 }
2738         }
2739
2740         final public function startAtomic( $fname = __METHOD__ ) {
2741                 if ( !$this->mTrxLevel ) {
2742                         $this->begin( $fname, self::TRANSACTION_INTERNAL );
2743                         // If DBO_TRX is set, a series of startAtomic/endAtomic pairs will result
2744                         // in all changes being in one transaction to keep requests transactional.
2745                         if ( !$this->getFlag( self::DBO_TRX ) ) {
2746                                 $this->mTrxAutomaticAtomic = true;
2747                         }
2748                 }
2749
2750                 $this->mTrxAtomicLevels[] = $fname;
2751         }
2752
2753         final public function endAtomic( $fname = __METHOD__ ) {
2754                 if ( !$this->mTrxLevel ) {
2755                         throw new DBUnexpectedError( $this, "No atomic transaction is open (got $fname)." );
2756                 }
2757                 if ( !$this->mTrxAtomicLevels ||
2758                         array_pop( $this->mTrxAtomicLevels ) !== $fname
2759                 ) {
2760                         throw new DBUnexpectedError( $this, "Invalid atomic section ended (got $fname)." );
2761                 }
2762
2763                 if ( !$this->mTrxAtomicLevels && $this->mTrxAutomaticAtomic ) {
2764                         $this->commit( $fname, self::FLUSHING_INTERNAL );
2765                 }
2766         }
2767
2768         final public function doAtomicSection( $fname, callable $callback ) {
2769                 $this->startAtomic( $fname );
2770                 try {
2771                         $res = call_user_func_array( $callback, [ $this, $fname ] );
2772                 } catch ( Exception $e ) {
2773                         $this->rollback( $fname, self::FLUSHING_INTERNAL );
2774                         throw $e;
2775                 }
2776                 $this->endAtomic( $fname );
2777
2778                 return $res;
2779         }
2780
2781         final public function begin( $fname = __METHOD__, $mode = self::TRANSACTION_EXPLICIT ) {
2782                 // Protect against mismatched atomic section, transaction nesting, and snapshot loss
2783                 if ( $this->mTrxLevel ) {
2784                         if ( $this->mTrxAtomicLevels ) {
2785                                 $levels = implode( ', ', $this->mTrxAtomicLevels );
2786                                 $msg = "$fname: Got explicit BEGIN while atomic section(s) $levels are open.";
2787                                 throw new DBUnexpectedError( $this, $msg );
2788                         } elseif ( !$this->mTrxAutomatic ) {
2789                                 $msg = "$fname: Explicit transaction already active (from {$this->mTrxFname}).";
2790                                 throw new DBUnexpectedError( $this, $msg );
2791                         } else {
2792                                 // @TODO: make this an exception at some point
2793                                 $msg = "$fname: Implicit transaction already active (from {$this->mTrxFname}).";
2794                                 $this->queryLogger->error( $msg );
2795                                 return; // join the main transaction set
2796                         }
2797                 } elseif ( $this->getFlag( self::DBO_TRX ) && $mode !== self::TRANSACTION_INTERNAL ) {
2798                         // @TODO: make this an exception at some point
2799                         $msg = "$fname: Implicit transaction expected (DBO_TRX set).";
2800                         $this->queryLogger->error( $msg );
2801                         return; // let any writes be in the main transaction
2802                 }
2803
2804                 // Avoid fatals if close() was called
2805                 $this->assertOpen();
2806
2807                 $this->doBegin( $fname );
2808                 $this->mTrxTimestamp = microtime( true );
2809                 $this->mTrxFname = $fname;
2810                 $this->mTrxDoneWrites = false;
2811                 $this->mTrxAutomaticAtomic = false;
2812                 $this->mTrxAtomicLevels = [];
2813                 $this->mTrxShortId = sprintf( '%06x', mt_rand( 0, 0xffffff ) );
2814                 $this->mTrxWriteDuration = 0.0;
2815                 $this->mTrxWriteQueryCount = 0;
2816                 $this->mTrxWriteAffectedRows = 0;
2817                 $this->mTrxWriteAdjDuration = 0.0;
2818                 $this->mTrxWriteAdjQueryCount = 0;
2819                 $this->mTrxWriteCallers = [];
2820                 // First SELECT after BEGIN will establish the snapshot in REPEATABLE-READ.
2821                 // Get an estimate of the replica DB lag before then, treating estimate staleness
2822                 // as lag itself just to be safe
2823                 $status = $this->getApproximateLagStatus();
2824                 $this->mTrxReplicaLag = $status['lag'] + ( microtime( true ) - $status['since'] );
2825                 // T147697: make explicitTrxActive() return true until begin() finishes. This way, no
2826                 // caller will think its OK to muck around with the transaction just because startAtomic()
2827                 // has not yet completed (e.g. setting mTrxAtomicLevels).
2828                 $this->mTrxAutomatic = ( $mode === self::TRANSACTION_INTERNAL );
2829         }
2830
2831         /**
2832          * Issues the BEGIN command to the database server.
2833          *
2834          * @see Database::begin()
2835          * @param string $fname
2836          */
2837         protected function doBegin( $fname ) {
2838                 $this->query( 'BEGIN', $fname );
2839                 $this->mTrxLevel = 1;
2840         }
2841
2842         final public function commit( $fname = __METHOD__, $flush = '' ) {
2843                 if ( $this->mTrxLevel && $this->mTrxAtomicLevels ) {
2844                         // There are still atomic sections open. This cannot be ignored
2845                         $levels = implode( ', ', $this->mTrxAtomicLevels );
2846                         throw new DBUnexpectedError(
2847                                 $this,
2848                                 "$fname: Got COMMIT while atomic sections $levels are still open."
2849                         );
2850                 }
2851
2852                 if ( $flush === self::FLUSHING_INTERNAL || $flush === self::FLUSHING_ALL_PEERS ) {
2853                         if ( !$this->mTrxLevel ) {
2854                                 return; // nothing to do
2855                         } elseif ( !$this->mTrxAutomatic ) {
2856                                 throw new DBUnexpectedError(
2857                                         $this,
2858                                         "$fname: Flushing an explicit transaction, getting out of sync."
2859                                 );
2860                         }
2861                 } else {
2862                         if ( !$this->mTrxLevel ) {
2863                                 $this->queryLogger->error(
2864                                         "$fname: No transaction to commit, something got out of sync." );
2865                                 return; // nothing to do
2866                         } elseif ( $this->mTrxAutomatic ) {
2867                                 // @TODO: make this an exception at some point
2868                                 $msg = "$fname: Explicit commit of implicit transaction.";
2869                                 $this->queryLogger->error( $msg );
2870                                 return; // wait for the main transaction set commit round
2871                         }
2872                 }
2873
2874                 // Avoid fatals if close() was called
2875                 $this->assertOpen();
2876
2877                 $this->runOnTransactionPreCommitCallbacks();
2878                 $writeTime = $this->pendingWriteQueryDuration( self::ESTIMATE_DB_APPLY );
2879                 $this->doCommit( $fname );
2880                 if ( $this->mTrxDoneWrites ) {
2881                         $this->mLastWriteTime = microtime( true );
2882                         $this->trxProfiler->transactionWritingOut(
2883                                 $this->mServer,
2884                                 $this->mDBname,
2885                                 $this->mTrxShortId,
2886                                 $writeTime,
2887                                 $this->mTrxWriteAffectedRows
2888                         );
2889                 }
2890
2891                 $this->runOnTransactionIdleCallbacks( self::TRIGGER_COMMIT );
2892                 $this->runTransactionListenerCallbacks( self::TRIGGER_COMMIT );
2893         }
2894
2895         /**
2896          * Issues the COMMIT command to the database server.
2897          *
2898          * @see Database::commit()
2899          * @param string $fname
2900          */
2901         protected function doCommit( $fname ) {
2902                 if ( $this->mTrxLevel ) {
2903                         $this->query( 'COMMIT', $fname );
2904                         $this->mTrxLevel = 0;
2905                 }
2906         }
2907
2908         final public function rollback( $fname = __METHOD__, $flush = '' ) {
2909                 if ( $flush === self::FLUSHING_INTERNAL || $flush === self::FLUSHING_ALL_PEERS ) {
2910                         if ( !$this->mTrxLevel ) {
2911                                 return; // nothing to do
2912                         }
2913                 } else {
2914                         if ( !$this->mTrxLevel ) {
2915                                 $this->queryLogger->error(
2916                                         "$fname: No transaction to rollback, something got out of sync." );
2917                                 return; // nothing to do
2918                         } elseif ( $this->getFlag( self::DBO_TRX ) ) {
2919                                 throw new DBUnexpectedError(
2920                                         $this,
2921                                         "$fname: Expected mass rollback of all peer databases (DBO_TRX set)."
2922                                 );
2923                         }
2924                 }
2925
2926                 // Avoid fatals if close() was called
2927                 $this->assertOpen();
2928
2929                 $this->doRollback( $fname );
2930                 $this->mTrxAtomicLevels = [];
2931                 if ( $this->mTrxDoneWrites ) {
2932                         $this->trxProfiler->transactionWritingOut(
2933                                 $this->mServer,
2934                                 $this->mDBname,
2935                                 $this->mTrxShortId
2936                         );
2937                 }
2938
2939                 $this->mTrxIdleCallbacks = []; // clear
2940                 $this->mTrxPreCommitCallbacks = []; // clear
2941                 $this->runOnTransactionIdleCallbacks( self::TRIGGER_ROLLBACK );
2942                 $this->runTransactionListenerCallbacks( self::TRIGGER_ROLLBACK );
2943         }
2944
2945         /**
2946          * Issues the ROLLBACK command to the database server.
2947          *
2948          * @see Database::rollback()
2949          * @param string $fname
2950          */
2951         protected function doRollback( $fname ) {
2952                 if ( $this->mTrxLevel ) {
2953                         # Disconnects cause rollback anyway, so ignore those errors
2954                         $ignoreErrors = true;
2955                         $this->query( 'ROLLBACK', $fname, $ignoreErrors );
2956                         $this->mTrxLevel = 0;
2957                 }
2958         }
2959
2960         public function flushSnapshot( $fname = __METHOD__ ) {
2961                 if ( $this->writesOrCallbacksPending() || $this->explicitTrxActive() ) {
2962                         // This only flushes transactions to clear snapshots, not to write data
2963                         $fnames = implode( ', ', $this->pendingWriteAndCallbackCallers() );
2964                         throw new DBUnexpectedError(
2965                                 $this,
2966                                 "$fname: Cannot flush snapshot because writes are pending ($fnames)."
2967                         );
2968                 }
2969
2970                 $this->commit( $fname, self::FLUSHING_INTERNAL );
2971         }
2972
2973         public function explicitTrxActive() {
2974                 return $this->mTrxLevel && ( $this->mTrxAtomicLevels || !$this->mTrxAutomatic );
2975         }
2976
2977         public function duplicateTableStructure(
2978                 $oldName, $newName, $temporary = false, $fname = __METHOD__
2979         ) {
2980                 throw new RuntimeException( __METHOD__ . ' is not implemented in descendant class' );
2981         }
2982
2983         public function listTables( $prefix = null, $fname = __METHOD__ ) {
2984                 throw new RuntimeException( __METHOD__ . ' is not implemented in descendant class' );
2985         }
2986
2987         public function listViews( $prefix = null, $fname = __METHOD__ ) {
2988                 throw new RuntimeException( __METHOD__ . ' is not implemented in descendant class' );
2989         }
2990
2991         public function timestamp( $ts = 0 ) {
2992                 $t = new ConvertibleTimestamp( $ts );
2993                 // Let errors bubble up to avoid putting garbage in the DB
2994                 return $t->getTimestamp( TS_MW );
2995         }
2996
2997         public function timestampOrNull( $ts = null ) {
2998                 if ( is_null( $ts ) ) {
2999                         return null;
3000                 } else {
3001                         return $this->timestamp( $ts );
3002                 }
3003         }
3004
3005         /**
3006          * Take the result from a query, and wrap it in a ResultWrapper if
3007          * necessary. Boolean values are passed through as is, to indicate success
3008          * of write queries or failure.
3009          *
3010          * Once upon a time, Database::query() returned a bare MySQL result
3011          * resource, and it was necessary to call this function to convert it to
3012          * a wrapper. Nowadays, raw database objects are never exposed to external
3013          * callers, so this is unnecessary in external code.
3014          *
3015          * @param bool|ResultWrapper|resource|object $result
3016          * @return bool|ResultWrapper
3017          */
3018         protected function resultObject( $result ) {
3019                 if ( !$result ) {
3020                         return false;
3021                 } elseif ( $result instanceof ResultWrapper ) {
3022                         return $result;
3023                 } elseif ( $result === true ) {
3024                         // Successful write query
3025                         return $result;
3026                 } else {
3027                         return new ResultWrapper( $this, $result );
3028                 }
3029         }
3030
3031         public function ping( &$rtt = null ) {
3032                 // Avoid hitting the server if it was hit recently
3033                 if ( $this->isOpen() && ( microtime( true ) - $this->lastPing ) < self::PING_TTL ) {
3034                         if ( !func_num_args() || $this->mRTTEstimate > 0 ) {
3035                                 $rtt = $this->mRTTEstimate;
3036                                 return true; // don't care about $rtt
3037                         }
3038                 }
3039
3040                 // This will reconnect if possible or return false if not
3041                 $this->clearFlag( self::DBO_TRX, self::REMEMBER_PRIOR );
3042                 $ok = ( $this->query( self::PING_QUERY, __METHOD__, true ) !== false );
3043                 $this->restoreFlags( self::RESTORE_PRIOR );
3044
3045                 if ( $ok ) {
3046                         $rtt = $this->mRTTEstimate;
3047                 }
3048
3049                 return $ok;
3050         }
3051
3052         /**
3053          * Close existing database connection and open a new connection
3054          *
3055          * @return bool True if new connection is opened successfully, false if error
3056          */
3057         protected function reconnect() {
3058                 $this->closeConnection();
3059                 $this->mOpened = false;
3060                 $this->mConn = false;
3061                 try {
3062                         $this->open( $this->mServer, $this->mUser, $this->mPassword, $this->mDBname );
3063                         $this->lastPing = microtime( true );
3064                         $ok = true;
3065                 } catch ( DBConnectionError $e ) {
3066                         $ok = false;
3067                 }
3068
3069                 return $ok;
3070         }
3071
3072         public function getSessionLagStatus() {
3073                 return $this->getTransactionLagStatus() ?: $this->getApproximateLagStatus();
3074         }
3075
3076         /**
3077          * Get the replica DB lag when the current transaction started
3078          *
3079          * This is useful when transactions might use snapshot isolation
3080          * (e.g. REPEATABLE-READ in innodb), so the "real" lag of that data
3081          * is this lag plus transaction duration. If they don't, it is still
3082          * safe to be pessimistic. This returns null if there is no transaction.
3083          *
3084          * @return array|null ('lag': seconds or false on error, 'since': UNIX timestamp of BEGIN)
3085          * @since 1.27
3086          */
3087         protected function getTransactionLagStatus() {
3088                 return $this->mTrxLevel
3089                         ? [ 'lag' => $this->mTrxReplicaLag, 'since' => $this->trxTimestamp() ]
3090                         : null;
3091         }
3092
3093         /**
3094          * Get a replica DB lag estimate for this server
3095          *
3096          * @return array ('lag': seconds or false on error, 'since': UNIX timestamp of estimate)
3097          * @since 1.27
3098          */
3099         protected function getApproximateLagStatus() {
3100                 return [
3101                         'lag'   => $this->getLBInfo( 'replica' ) ? $this->getLag() : 0,
3102                         'since' => microtime( true )
3103                 ];
3104         }
3105
3106         /**
3107          * Merge the result of getSessionLagStatus() for several DBs
3108          * using the most pessimistic values to estimate the lag of
3109          * any data derived from them in combination
3110          *
3111          * This is information is useful for caching modules
3112          *
3113          * @see WANObjectCache::set()
3114          * @see WANObjectCache::getWithSetCallback()
3115          *
3116          * @param IDatabase $db1
3117          * @param IDatabase ...
3118          * @return array Map of values:
3119          *   - lag: highest lag of any of the DBs or false on error (e.g. replication stopped)
3120          *   - since: oldest UNIX timestamp of any of the DB lag estimates
3121          *   - pending: whether any of the DBs have uncommitted changes
3122          * @since 1.27
3123          */
3124         public static function getCacheSetOptions( IDatabase $db1 ) {
3125                 $res = [ 'lag' => 0, 'since' => INF, 'pending' => false ];
3126                 foreach ( func_get_args() as $db ) {
3127                         /** @var IDatabase $db */
3128                         $status = $db->getSessionLagStatus();
3129                         if ( $status['lag'] === false ) {
3130                                 $res['lag'] = false;
3131                         } elseif ( $res['lag'] !== false ) {
3132                                 $res['lag'] = max( $res['lag'], $status['lag'] );
3133                         }
3134                         $res['since'] = min( $res['since'], $status['since'] );
3135                         $res['pending'] = $res['pending'] ?: $db->writesPending();
3136                 }
3137
3138                 return $res;
3139         }
3140
3141         public function getLag() {
3142                 return 0;
3143         }
3144
3145         public function maxListLen() {
3146                 return 0;
3147         }
3148
3149         public function encodeBlob( $b ) {
3150                 return $b;
3151         }
3152
3153         public function decodeBlob( $b ) {
3154                 if ( $b instanceof Blob ) {
3155                         $b = $b->fetch();
3156                 }
3157                 return $b;
3158         }
3159
3160         public function setSessionOptions( array $options ) {
3161         }
3162
3163         public function sourceFile(
3164                 $filename,
3165                 callable $lineCallback = null,
3166                 callable $resultCallback = null,
3167                 $fname = false,
3168                 callable $inputCallback = null
3169         ) {
3170                 MediaWiki\suppressWarnings();
3171                 $fp = fopen( $filename, 'r' );
3172                 MediaWiki\restoreWarnings();
3173
3174                 if ( false === $fp ) {
3175                         throw new RuntimeException( "Could not open \"{$filename}\".\n" );
3176                 }
3177
3178                 if ( !$fname ) {
3179                         $fname = __METHOD__ . "( $filename )";
3180                 }
3181
3182                 try {
3183                         $error = $this->sourceStream(
3184                                 $fp, $lineCallback, $resultCallback, $fname, $inputCallback );
3185                 } catch ( Exception $e ) {
3186                         fclose( $fp );
3187                         throw $e;
3188                 }
3189
3190                 fclose( $fp );
3191
3192                 return $error;
3193         }
3194
3195         public function setSchemaVars( $vars ) {
3196                 $this->mSchemaVars = $vars;
3197         }
3198
3199         public function sourceStream(
3200                 $fp,
3201                 callable $lineCallback = null,
3202                 callable $resultCallback = null,
3203                 $fname = __METHOD__,
3204                 callable $inputCallback = null
3205         ) {
3206                 $cmd = '';
3207
3208                 while ( !feof( $fp ) ) {
3209                         if ( $lineCallback ) {
3210                                 call_user_func( $lineCallback );
3211                         }
3212
3213                         $line = trim( fgets( $fp ) );
3214
3215                         if ( $line == '' ) {
3216                                 continue;
3217                         }
3218
3219                         if ( '-' == $line[0] && '-' == $line[1] ) {
3220                                 continue;
3221                         }
3222
3223                         if ( $cmd != '' ) {
3224                                 $cmd .= ' ';
3225                         }
3226
3227                         $done = $this->streamStatementEnd( $cmd, $line );
3228
3229                         $cmd .= "$line\n";
3230
3231                         if ( $done || feof( $fp ) ) {
3232                                 $cmd = $this->replaceVars( $cmd );
3233
3234                                 if ( !$inputCallback || call_user_func( $inputCallback, $cmd ) ) {
3235                                         $res = $this->query( $cmd, $fname );
3236
3237                                         if ( $resultCallback ) {
3238                                                 call_user_func( $resultCallback, $res, $this );
3239                                         }
3240
3241                                         if ( false === $res ) {
3242                                                 $err = $this->lastError();
3243
3244                                                 return "Query \"{$cmd}\" failed with error code \"$err\".\n";
3245                                         }
3246                                 }
3247                                 $cmd = '';
3248                         }
3249                 }
3250
3251                 return true;
3252         }
3253
3254         /**
3255          * Called by sourceStream() to check if we've reached a statement end
3256          *
3257          * @param string &$sql SQL assembled so far
3258          * @param string &$newLine New line about to be added to $sql
3259          * @return bool Whether $newLine contains end of the statement
3260          */
3261         public function streamStatementEnd( &$sql, &$newLine ) {
3262                 if ( $this->delimiter ) {
3263                         $prev = $newLine;
3264                         $newLine = preg_replace(
3265                                 '/' . preg_quote( $this->delimiter, '/' ) . '$/', '', $newLine );
3266                         if ( $newLine != $prev ) {
3267                                 return true;
3268                         }
3269                 }
3270
3271                 return false;
3272         }
3273
3274         /**
3275          * Database independent variable replacement. Replaces a set of variables
3276          * in an SQL statement with their contents as given by $this->getSchemaVars().
3277          *
3278          * Supports '{$var}' `{$var}` and / *$var* / (without the spaces) style variables.
3279          *
3280          * - '{$var}' should be used for text and is passed through the database's
3281          *   addQuotes method.
3282          * - `{$var}` should be used for identifiers (e.g. table and database names).
3283          *   It is passed through the database's addIdentifierQuotes method which
3284          *   can be overridden if the database uses something other than backticks.
3285          * - / *_* / or / *$wgDBprefix* / passes the name that follows through the
3286          *   database's tableName method.
3287          * - / *i* / passes the name that follows through the database's indexName method.
3288          * - In all other cases, / *$var* / is left unencoded. Except for table options,
3289          *   its use should be avoided. In 1.24 and older, string encoding was applied.
3290          *
3291          * @param string $ins SQL statement to replace variables in
3292          * @return string The new SQL statement with variables replaced
3293          */
3294         protected function replaceVars( $ins ) {
3295                 $vars = $this->getSchemaVars();
3296                 return preg_replace_callback(
3297                         '!
3298                                 /\* (\$wgDBprefix|[_i]) \*/ (\w*) | # 1-2. tableName, indexName
3299                                 \'\{\$ (\w+) }\'                  | # 3. addQuotes
3300                                 `\{\$ (\w+) }`                    | # 4. addIdentifierQuotes
3301                                 /\*\$ (\w+) \*/                     # 5. leave unencoded
3302                         !x',
3303                         function ( $m ) use ( $vars ) {
3304                                 // Note: Because of <https://bugs.php.net/bug.php?id=51881>,
3305                                 // check for both nonexistent keys *and* the empty string.
3306                                 if ( isset( $m[1] ) && $m[1] !== '' ) {
3307                                         if ( $m[1] === 'i' ) {
3308                                                 return $this->indexName( $m[2] );
3309                                         } else {
3310                                                 return $this->tableName( $m[2] );
3311                                         }
3312                                 } elseif ( isset( $m[3] ) && $m[3] !== '' && array_key_exists( $m[3], $vars ) ) {
3313                                         return $this->addQuotes( $vars[$m[3]] );
3314                                 } elseif ( isset( $m[4] ) && $m[4] !== '' && array_key_exists( $m[4], $vars ) ) {
3315                                         return $this->addIdentifierQuotes( $vars[$m[4]] );
3316                                 } elseif ( isset( $m[5] ) && $m[5] !== '' && array_key_exists( $m[5], $vars ) ) {
3317                                         return $vars[$m[5]];
3318                                 } else {
3319                                         return $m[0];
3320                                 }
3321                         },
3322                         $ins
3323                 );
3324         }
3325
3326         /**
3327          * Get schema variables. If none have been set via setSchemaVars(), then
3328          * use some defaults from the current object.
3329          *
3330          * @return array
3331          */
3332         protected function getSchemaVars() {
3333                 if ( $this->mSchemaVars ) {
3334                         return $this->mSchemaVars;
3335                 } else {
3336                         return $this->getDefaultSchemaVars();
3337                 }
3338         }
3339
3340         /**
3341          * Get schema variables to use if none have been set via setSchemaVars().
3342          *
3343          * Override this in derived classes to provide variables for tables.sql
3344          * and SQL patch files.
3345          *
3346          * @return array
3347          */
3348         protected function getDefaultSchemaVars() {
3349                 return [];
3350         }
3351
3352         public function lockIsFree( $lockName, $method ) {
3353                 return true;
3354         }
3355
3356         public function lock( $lockName, $method, $timeout = 5 ) {
3357                 $this->mNamedLocksHeld[$lockName] = 1;
3358
3359                 return true;
3360         }
3361
3362         public function unlock( $lockName, $method ) {
3363                 unset( $this->mNamedLocksHeld[$lockName] );
3364
3365                 return true;
3366         }
3367
3368         public function getScopedLockAndFlush( $lockKey, $fname, $timeout ) {
3369                 if ( $this->writesOrCallbacksPending() ) {
3370                         // This only flushes transactions to clear snapshots, not to write data
3371                         $fnames = implode( ', ', $this->pendingWriteAndCallbackCallers() );
3372                         throw new DBUnexpectedError(
3373                                 $this,
3374                                 "$fname: Cannot flush pre-lock snapshot because writes are pending ($fnames)."
3375                         );
3376                 }
3377
3378                 if ( !$this->lock( $lockKey, $fname, $timeout ) ) {
3379                         return null;
3380                 }
3381
3382                 $unlocker = new ScopedCallback( function () use ( $lockKey, $fname ) {
3383                         if ( $this->trxLevel() ) {
3384                                 // There is a good chance an exception was thrown, causing any early return
3385                                 // from the caller. Let any error handler get a chance to issue rollback().
3386                                 // If there isn't one, let the error bubble up and trigger server-side rollback.
3387                                 $this->onTransactionResolution(
3388                                         function () use ( $lockKey, $fname ) {
3389                                                 $this->unlock( $lockKey, $fname );
3390                                         },
3391                                         $fname
3392                                 );
3393                         } else {
3394                                 $this->unlock( $lockKey, $fname );
3395                         }
3396                 } );
3397
3398                 $this->commit( $fname, self::FLUSHING_INTERNAL );
3399
3400                 return $unlocker;
3401         }
3402
3403         public function namedLocksEnqueue() {
3404                 return false;
3405         }
3406
3407         public function tableLocksHaveTransactionScope() {
3408                 return true;
3409         }
3410
3411         final public function lockTables( array $read, array $write, $method ) {
3412                 if ( $this->writesOrCallbacksPending() ) {
3413                         throw new DBUnexpectedError( $this, "Transaction writes or callbacks still pending." );
3414                 }
3415
3416                 if ( $this->tableLocksHaveTransactionScope() ) {
3417                         $this->startAtomic( $method );
3418                 }
3419
3420                 return $this->doLockTables( $read, $write, $method );
3421         }
3422
3423         /**
3424          * Helper function for lockTables() that handles the actual table locking
3425          *
3426          * @param array $read Array of tables to lock for read access
3427          * @param array $write Array of tables to lock for write access
3428          * @param string $method Name of caller
3429          * @return true
3430          */
3431         protected function doLockTables( array $read, array $write, $method ) {
3432                 return true;
3433         }
3434
3435         final public function unlockTables( $method ) {
3436                 if ( $this->tableLocksHaveTransactionScope() ) {
3437                         $this->endAtomic( $method );
3438
3439                         return true; // locks released on COMMIT/ROLLBACK
3440                 }
3441
3442                 return $this->doUnlockTables( $method );
3443         }
3444
3445         /**
3446          * Helper function for unlockTables() that handles the actual table unlocking
3447          *
3448          * @param string $method Name of caller
3449          * @return true
3450          */
3451         protected function doUnlockTables( $method ) {
3452                 return true;
3453         }
3454
3455         /**
3456          * Delete a table
3457          * @param string $tableName
3458          * @param string $fName
3459          * @return bool|ResultWrapper
3460          * @since 1.18
3461          */
3462         public function dropTable( $tableName, $fName = __METHOD__ ) {
3463                 if ( !$this->tableExists( $tableName, $fName ) ) {
3464                         return false;
3465                 }
3466                 $sql = "DROP TABLE " . $this->tableName( $tableName ) . " CASCADE";
3467
3468                 return $this->query( $sql, $fName );
3469         }
3470
3471         public function getInfinity() {
3472                 return 'infinity';
3473         }
3474
3475         public function encodeExpiry( $expiry ) {
3476                 return ( $expiry == '' || $expiry == 'infinity' || $expiry == $this->getInfinity() )
3477                         ? $this->getInfinity()
3478                         : $this->timestamp( $expiry );
3479         }
3480
3481         public function decodeExpiry( $expiry, $format = TS_MW ) {
3482                 if ( $expiry == '' || $expiry == 'infinity' || $expiry == $this->getInfinity() ) {
3483                         return 'infinity';
3484                 }
3485
3486                 return ConvertibleTimestamp::convert( $format, $expiry );
3487         }
3488
3489         public function setBigSelects( $value = true ) {
3490                 // no-op
3491         }
3492
3493         public function isReadOnly() {
3494                 return ( $this->getReadOnlyReason() !== false );
3495         }
3496
3497         /**
3498          * @return string|bool Reason this DB is read-only or false if it is not
3499          */
3500         protected function getReadOnlyReason() {
3501                 $reason = $this->getLBInfo( 'readOnlyReason' );
3502
3503                 return is_string( $reason ) ? $reason : false;
3504         }
3505
3506         public function setTableAliases( array $aliases ) {
3507                 $this->tableAliases = $aliases;
3508         }
3509
3510         /**
3511          * @return bool Whether a DB user is required to access the DB
3512          * @since 1.28
3513          */
3514         protected function requiresDatabaseUser() {
3515                 return true;
3516         }
3517
3518         /**
3519          * Get the underlying binding handle, mConn
3520          *
3521          * Makes sure that mConn is set (disconnects and ping() failure can unset it).
3522          * This catches broken callers than catch and ignore disconnection exceptions.
3523          * Unlike checking isOpen(), this is safe to call inside of open().
3524          *
3525          * @return resource|object
3526          * @throws DBUnexpectedError
3527          * @since 1.26
3528          */
3529         protected function getBindingHandle() {
3530                 if ( !$this->mConn ) {
3531                         throw new DBUnexpectedError(
3532                                 $this,
3533                                 'DB connection was already closed or the connection dropped.'
3534                         );
3535                 }
3536
3537                 return $this->mConn;
3538         }
3539
3540         /**
3541          * @since 1.19
3542          * @return string
3543          */
3544         public function __toString() {
3545                 return (string)$this->mConn;
3546         }
3547
3548         /**
3549          * Make sure that copies do not share the same client binding handle
3550          * @throws DBConnectionError
3551          */
3552         public function __clone() {
3553                 $this->connLogger->warning(
3554                         "Cloning " . static::class . " is not recomended; forking connection:\n" .
3555                         ( new RuntimeException() )->getTraceAsString()
3556                 );
3557
3558                 if ( $this->isOpen() ) {
3559                         // Open a new connection resource without messing with the old one
3560                         $this->mOpened = false;
3561                         $this->mConn = false;
3562                         $this->mTrxEndCallbacks = []; // don't copy
3563                         $this->handleSessionLoss(); // no trx or locks anymore
3564                         $this->open( $this->mServer, $this->mUser, $this->mPassword, $this->mDBname );
3565                         $this->lastPing = microtime( true );
3566                 }
3567         }
3568
3569         /**
3570          * Called by serialize. Throw an exception when DB connection is serialized.
3571          * This causes problems on some database engines because the connection is
3572          * not restored on unserialize.
3573          */
3574         public function __sleep() {
3575                 throw new RuntimeException( 'Database serialization may cause problems, since ' .
3576                         'the connection is not restored on wakeup.' );
3577         }
3578
3579         /**
3580          * Run a few simple sanity checks and close dangling connections
3581          */
3582         public function __destruct() {
3583                 if ( $this->mTrxLevel && $this->mTrxDoneWrites ) {
3584                         trigger_error( "Uncommitted DB writes (transaction from {$this->mTrxFname})." );
3585                 }
3586
3587                 $danglingWriters = $this->pendingWriteAndCallbackCallers();
3588                 if ( $danglingWriters ) {
3589                         $fnames = implode( ', ', $danglingWriters );
3590                         trigger_error( "DB transaction writes or callbacks still pending ($fnames)." );
3591                 }
3592
3593                 if ( $this->mConn ) {
3594                         // Avoid connection leaks for sanity. Normally, resources close at script completion.
3595                         // The connection might already be closed in zend/hhvm by now, so suppress warnings.
3596                         \MediaWiki\suppressWarnings();
3597                         $this->closeConnection();
3598                         \MediaWiki\restoreWarnings();
3599                         $this->mConn = false;
3600                         $this->mOpened = false;
3601                 }
3602         }
3603 }
3604
3605 class_alias( Database::class, 'DatabaseBase' ); // b/c for old name
3606 class_alias( Database::class, 'Database' ); // b/c global alias