includes/libs/rdbms/database/Database.php

   1 <?php
   2 /**
   3  * @defgroup Database Database
   4  *
   5  * This file deals with database interface functions
   6  * and query specifics/optimisations.
   7  *
   8  * This program is free software; you can redistribute it and/or modify
   9  * it under the terms of the GNU General Public License as published by
  10  * the Free Software Foundation; either version 2 of the License, or
  11  * (at your option) any later version.
  12  *
  13  * This program is distributed in the hope that it will be useful,
  14  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  15  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
  16  * GNU General Public License for more details.
  17  *
  18  * You should have received a copy of the GNU General Public License along
  19  * with this program; if not, write to the Free Software Foundation, Inc.,
  20  * 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
  21  * http://www.gnu.org/copyleft/gpl.html
  22  *
  23  * @file
  24  * @ingroup Database
  25  */
  26 namespace Wikimedia\Rdbms;
  27
  28 use Psr\Log\LoggerAwareInterface;
  29 use Psr\Log\LoggerInterface;
  30 use Wikimedia\ScopedCallback;
  31 use Wikimedia\Timestamp\ConvertibleTimestamp;
  32 use MediaWiki;
  33 use BagOStuff;
  34 use HashBagOStuff;
  35 use InvalidArgumentException;
  36 use Exception;
  37 use RuntimeException;
  38
  39 /**
  40  * Relational database abstraction object
  41  *
  42  * @ingroup Database
  43  * @since 1.28
  44  */
  45 abstract class Database implements IDatabase, IMaintainableDatabase, LoggerAwareInterface {
  46         /** Number of times to re-try an operation in case of deadlock */
  47         const DEADLOCK_TRIES = 4;
  48         /** Minimum time to wait before retry, in microseconds */
  49         const DEADLOCK_DELAY_MIN = 500000;
  50         /** Maximum time to wait before retry */
  51         const DEADLOCK_DELAY_MAX = 1500000;
  52
  53         /** How long before it is worth doing a dummy query to test the connection */
  54         const PING_TTL = 1.0;
  55         const PING_QUERY = 'SELECT 1 AS ping';
  56
  57         const TINY_WRITE_SEC = 0.010;
  58         const SLOW_WRITE_SEC = 0.500;
  59         const SMALL_WRITE_ROWS = 100;
  60
  61         /** @var string SQL query */
  62         protected $mLastQuery = '';
  63         /** @var float|bool UNIX timestamp of last write query */
  64         protected $mLastWriteTime = false;
  65         /** @var string|bool */
  66         protected $mPHPError = false;
  67         /** @var string */
  68         protected $mServer;
  69         /** @var string */
  70         protected $mUser;
  71         /** @var string */
  72         protected $mPassword;
  73         /** @var string */
  74         protected $mDBname;
  75         /** @var array[] $aliases Map of (table => (dbname, schema, prefix) map) */
  76         protected $tableAliases = [];
  77         /** @var bool Whether this PHP instance is for a CLI script */
  78         protected $cliMode;
  79         /** @var string Agent name for query profiling */
  80         protected $agent;
  81
  82         /** @var BagOStuff APC cache */
  83         protected $srvCache;
  84         /** @var LoggerInterface */
  85         protected $connLogger;
  86         /** @var LoggerInterface */
  87         protected $queryLogger;
  88         /** @var callback Error logging callback */
  89         protected $errorLogger;
  90
  91         /** @var resource|null Database connection */
  92         protected $mConn = null;
  93         /** @var bool */
  94         protected $mOpened = false;
  95
  96         /** @var array[] List of (callable, method name) */
  97         protected $mTrxIdleCallbacks = [];
  98         /** @var array[] List of (callable, method name) */
  99         protected $mTrxPreCommitCallbacks = [];
 100         /** @var array[] List of (callable, method name) */
 101         protected $mTrxEndCallbacks = [];
 102         /** @var callable[] Map of (name => callable) */
 103         protected $mTrxRecurringCallbacks = [];
 104         /** @var bool Whether to suppress triggering of transaction end callbacks */
 105         protected $mTrxEndCallbacksSuppressed = false;
 106
 107         /** @var string */
 108         protected $mTablePrefix = '';
 109         /** @var string */
 110         protected $mSchema = '';
 111         /** @var int */
 112         protected $mFlags;
 113         /** @var array */
 114         protected $mLBInfo = [];
 115         /** @var bool|null */
 116         protected $mDefaultBigSelects = null;
 117         /** @var array|bool */
 118         protected $mSchemaVars = false;
 119         /** @var array */
 120         protected $mSessionVars = [];
 121         /** @var array|null */
 122         protected $preparedArgs;
 123         /** @var string|bool|null Stashed value of html_errors INI setting */
 124         protected $htmlErrors;
 125         /** @var string */
 126         protected $delimiter = ';';
 127         /** @var DatabaseDomain */
 128         protected $currentDomain;
 129
 130         /**
 131          * Either 1 if a transaction is active or 0 otherwise.
 132          * The other Trx fields may not be meaningfull if this is 0.
 133          *
 134          * @var int
 135          */
 136         protected $mTrxLevel = 0;
 137         /**
 138          * Either a short hexidecimal string if a transaction is active or ""
 139          *
 140          * @var string
 141          * @see Database::mTrxLevel
 142          */
 143         protected $mTrxShortId = '';
 144         /**
 145          * The UNIX time that the transaction started. Callers can assume that if
 146          * snapshot isolation is used, then the data is *at least* up to date to that
 147          * point (possibly more up-to-date since the first SELECT defines the snapshot).
 148          *
 149          * @var float|null
 150          * @see Database::mTrxLevel
 151          */
 152         private $mTrxTimestamp = null;
 153         /** @var float Lag estimate at the time of BEGIN */
 154         private $mTrxReplicaLag = null;
 155         /**
 156          * Remembers the function name given for starting the most recent transaction via begin().
 157          * Used to provide additional context for error reporting.
 158          *
 159          * @var string
 160          * @see Database::mTrxLevel
 161          */
 162         private $mTrxFname = null;
 163         /**
 164          * Record if possible write queries were done in the last transaction started
 165          *
 166          * @var bool
 167          * @see Database::mTrxLevel
 168          */
 169         private $mTrxDoneWrites = false;
 170         /**
 171          * Record if the current transaction was started implicitly due to DBO_TRX being set.
 172          *
 173          * @var bool
 174          * @see Database::mTrxLevel
 175          */
 176         private $mTrxAutomatic = false;
 177         /**
 178          * Array of levels of atomicity within transactions
 179          *
 180          * @var array
 181          */
 182         private $mTrxAtomicLevels = [];
 183         /**
 184          * Record if the current transaction was started implicitly by Database::startAtomic
 185          *
 186          * @var bool
 187          */
 188         private $mTrxAutomaticAtomic = false;
 189         /**
 190          * Track the write query callers of the current transaction
 191          *
 192          * @var string[]
 193          */
 194         private $mTrxWriteCallers = [];
 195         /**
 196          * @var float Seconds spent in write queries for the current transaction
 197          */
 198         private $mTrxWriteDuration = 0.0;
 199         /**
 200          * @var int Number of write queries for the current transaction
 201          */
 202         private $mTrxWriteQueryCount = 0;
 203         /**
 204          * @var int Number of rows affected by write queries for the current transaction
 205          */
 206         private $mTrxWriteAffectedRows = 0;
 207         /**
 208          * @var float Like mTrxWriteQueryCount but excludes lock-bound, easy to replicate, queries
 209          */
 210         private $mTrxWriteAdjDuration = 0.0;
 211         /**
 212          * @var int Number of write queries counted in mTrxWriteAdjDuration
 213          */
 214         private $mTrxWriteAdjQueryCount = 0;
 215         /**
 216          * @var float RTT time estimate
 217          */
 218         private $mRTTEstimate = 0.0;
 219
 220         /** @var array Map of (name => 1) for locks obtained via lock() */
 221         private $mNamedLocksHeld = [];
 222         /** @var array Map of (table name => 1) for TEMPORARY tables */
 223         protected $mSessionTempTables = [];
 224
 225         /** @var IDatabase|null Lazy handle to the master DB this server replicates from */
 226         private $lazyMasterHandle;
 227
 228         /** @var float UNIX timestamp */
 229         protected $lastPing = 0.0;
 230
 231         /** @var int[] Prior mFlags values */
 232         private $priorFlags = [];
 233
 234         /** @var object|string Class name or object With profileIn/profileOut methods */
 235         protected $profiler;
 236         /** @var TransactionProfiler */
 237         protected $trxProfiler;
 238
 239         /**
 240          * Constructor and database handle and attempt to connect to the DB server
 241          *
 242          * IDatabase classes should not be constructed directly in external
 243          * code. Database::factory() should be used instead.
 244          *
 245          * @param array $params Parameters passed from Database::factory()
 246          */
 247         function __construct( array $params ) {
 248                 $server = $params['host'];
 249                 $user = $params['user'];
 250                 $password = $params['password'];
 251                 $dbName = $params['dbname'];
 252
 253                 $this->mSchema = $params['schema'];
 254                 $this->mTablePrefix = $params['tablePrefix'];
 255
 256                 $this->cliMode = $params['cliMode'];
 257                 // Agent name is added to SQL queries in a comment, so make sure it can't break out
 258                 $this->agent = str_replace( '/', '-', $params['agent'] );
 259
 260                 $this->mFlags = $params['flags'];
 261                 if ( $this->mFlags & self::DBO_DEFAULT ) {
 262                         if ( $this->cliMode ) {
 263                                 $this->mFlags &= ~self::DBO_TRX;
 264                         } else {
 265                                 $this->mFlags |= self::DBO_TRX;
 266                         }
 267                 }
 268
 269                 $this->mSessionVars = $params['variables'];
 270
 271                 $this->srvCache = isset( $params['srvCache'] )
 272                         ? $params['srvCache']
 273                         : new HashBagOStuff();
 274
 275                 $this->profiler = $params['profiler'];
 276                 $this->trxProfiler = $params['trxProfiler'];
 277                 $this->connLogger = $params['connLogger'];
 278                 $this->queryLogger = $params['queryLogger'];
 279                 $this->errorLogger = $params['errorLogger'];
 280
 281                 // Set initial dummy domain until open() sets the final DB/prefix
 282                 $this->currentDomain = DatabaseDomain::newUnspecified();
 283
 284                 if ( $user ) {
 285                         $this->open( $server, $user, $password, $dbName );
 286                 } elseif ( $this->requiresDatabaseUser() ) {
 287                         throw new InvalidArgumentException( "No database user provided." );
 288                 }
 289
 290                 // Set the domain object after open() sets the relevant fields
 291                 if ( $this->mDBname != '' ) {
 292                         // Domains with server scope but a table prefix are not used by IDatabase classes
 293                         $this->currentDomain = new DatabaseDomain( $this->mDBname, null, $this->mTablePrefix );
 294                 }
 295         }
 296
 297         /**
 298          * Construct a Database subclass instance given a database type and parameters
 299          *
 300          * This also connects to the database immediately upon object construction
 301          *
 302          * @param string $dbType A possible DB type (sqlite, mysql, postgres)
 303          * @param array $p Parameter map with keys:
 304          *   - host : The hostname of the DB server
 305          *   - user : The name of the database user the client operates under
 306          *   - password : The password for the database user
 307          *   - dbname : The name of the database to use where queries do not specify one.
 308          *      The database must exist or an error might be thrown. Setting this to the empty string
 309          *      will avoid any such errors and make the handle have no implicit database scope. This is
 310          *      useful for queries like SHOW STATUS, CREATE DATABASE, or DROP DATABASE. Note that a
 311          *      "database" in Postgres is rougly equivalent to an entire MySQL server. This the domain
 312          *      in which user names and such are defined, e.g. users are database-specific in Postgres.
 313          *   - schema : The database schema to use (if supported). A "schema" in Postgres is roughly
 314          *      equivalent to a "database" in MySQL. Note that MySQL and SQLite do not use schemas.
 315          *   - tablePrefix : Optional table prefix that is implicitly added on to all table names
 316          *      recognized in queries. This can be used in place of schemas for handle site farms.
 317          *   - flags : Optional bitfield of DBO_* constants that define connection, protocol,
 318          *      buffering, and transaction behavior. It is STRONGLY adviced to leave the DBO_DEFAULT
 319          *      flag in place UNLESS this this database simply acts as a key/value store.
 320          *   - driver: Optional name of a specific DB client driver. For MySQL, there is the old
 321          *      'mysql' driver and the newer 'mysqli' driver.
 322          *   - variables: Optional map of session variables to set after connecting. This can be
 323          *      used to adjust lock timeouts or encoding modes and the like.
 324          *   - connLogger: Optional PSR-3 logger interface instance.
 325          *   - queryLogger: Optional PSR-3 logger interface instance.
 326          *   - profiler: Optional class name or object with profileIn()/profileOut() methods.
 327          *      These will be called in query(), using a simplified version of the SQL that also
 328          *      includes the agent as a SQL comment.
 329          *   - trxProfiler: Optional TransactionProfiler instance.
 330          *   - errorLogger: Optional callback that takes an Exception and logs it.
 331          *   - cliMode: Whether to consider the execution context that of a CLI script.
 332          *   - agent: Optional name used to identify the end-user in query profiling/logging.
 333          *   - srvCache: Optional BagOStuff instance to an APC-style cache.
 334          * @return Database|null If the database driver or extension cannot be found
 335          * @throws InvalidArgumentException If the database driver or extension cannot be found
 336          * @since 1.18
 337          */
 338         final public static function factory( $dbType, $p = [] ) {
 339                 static $canonicalDBTypes = [
 340                         'mysql' => [ 'mysqli', 'mysql' ],
 341                         'postgres' => [],
 342                         'sqlite' => [],
 343                         'oracle' => [],
 344                         'mssql' => [],
 345                 ];
 346                 static $classAliases = [
 347                         'DatabaseMssql' => DatabaseMssql::class,
 348                         'DatabaseMysql' => DatabaseMysql::class,
 349                         'DatabaseMysqli' => DatabaseMysqli::class,
 350                         'DatabaseSqlite' => DatabaseSqlite::class,
 351                         'DatabasePostgres' => DatabasePostgres::class
 352                 ];
 353
 354                 $driver = false;
 355                 $dbType = strtolower( $dbType );
 356                 if ( isset( $canonicalDBTypes[$dbType] ) && $canonicalDBTypes[$dbType] ) {
 357                         $possibleDrivers = $canonicalDBTypes[$dbType];
 358                         if ( !empty( $p['driver'] ) ) {
 359                                 if ( in_array( $p['driver'], $possibleDrivers ) ) {
 360                                         $driver = $p['driver'];
 361                                 } else {
 362                                         throw new InvalidArgumentException( __METHOD__ .
 363                                                 " type '$dbType' does not support driver '{$p['driver']}'" );
 364                                 }
 365                         } else {
 366                                 foreach ( $possibleDrivers as $posDriver ) {
 367                                         if ( extension_loaded( $posDriver ) ) {
 368                                                 $driver = $posDriver;
 369                                                 break;
 370                                         }
 371                                 }
 372                         }
 373                 } else {
 374                         $driver = $dbType;
 375                 }
 376
 377                 if ( $driver === false || $driver === '' ) {
 378                         throw new InvalidArgumentException( __METHOD__ .
 379                                 " no viable database extension found for type '$dbType'" );
 380                 }
 381
 382                 $class = 'Database' . ucfirst( $driver );
 383                 if ( isset( $classAliases[$class] ) ) {
 384                         $class = $classAliases[$class];
 385                 }
 386
 387                 if ( class_exists( $class ) && is_subclass_of( $class, IDatabase::class ) ) {
 388                         // Resolve some defaults for b/c
 389                         $p['host'] = isset( $p['host'] ) ? $p['host'] : false;
 390                         $p['user'] = isset( $p['user'] ) ? $p['user'] : false;
 391                         $p['password'] = isset( $p['password'] ) ? $p['password'] : false;
 392                         $p['dbname'] = isset( $p['dbname'] ) ? $p['dbname'] : false;
 393                         $p['flags'] = isset( $p['flags'] ) ? $p['flags'] : 0;
 394                         $p['variables'] = isset( $p['variables'] ) ? $p['variables'] : [];
 395                         $p['tablePrefix'] = isset( $p['tablePrefix'] ) ? $p['tablePrefix'] : '';
 396                         $p['schema'] = isset( $p['schema'] ) ? $p['schema'] : '';
 397                         $p['cliMode'] = isset( $p['cliMode'] )
 398                                 ? $p['cliMode']
 399                                 : ( PHP_SAPI === 'cli' || PHP_SAPI === 'phpdbg' );
 400                         $p['agent'] = isset( $p['agent'] ) ? $p['agent'] : '';
 401                         if ( !isset( $p['connLogger'] ) ) {
 402                                 $p['connLogger'] = new \Psr\Log\NullLogger();
 403                         }
 404                         if ( !isset( $p['queryLogger'] ) ) {
 405                                 $p['queryLogger'] = new \Psr\Log\NullLogger();
 406                         }
 407                         $p['profiler'] = isset( $p['profiler'] ) ? $p['profiler'] : null;
 408                         if ( !isset( $p['trxProfiler'] ) ) {
 409                                 $p['trxProfiler'] = new TransactionProfiler();
 410                         }
 411                         if ( !isset( $p['errorLogger'] ) ) {
 412                                 $p['errorLogger'] = function ( Exception $e ) {
 413                                         trigger_error( get_class( $e ) . ': ' . $e->getMessage(), E_USER_WARNING );
 414                                 };
 415                         }
 416
 417                         $conn = new $class( $p );
 418                 } else {
 419                         $conn = null;
 420                 }
 421
 422                 return $conn;
 423         }
 424
 425         /**
 426          * Set the PSR-3 logger interface to use for query logging. (The logger
 427          * interfaces for connection logging and error logging can be set with the
 428          * constructor.)
 429          *
 430          * @param LoggerInterface $logger
 431          */
 432         public function setLogger( LoggerInterface $logger ) {
 433                 $this->queryLogger = $logger;
 434         }
 435
 436         public function getServerInfo() {
 437                 return $this->getServerVersion();
 438         }
 439
 440         public function bufferResults( $buffer = null ) {
 441                 $res = !$this->getFlag( self::DBO_NOBUFFER );
 442                 if ( $buffer !== null ) {
 443                         $buffer
 444                                 ? $this->clearFlag( self::DBO_NOBUFFER )
 445                                 : $this->setFlag( self::DBO_NOBUFFER );
 446                 }
 447
 448                 return $res;
 449         }
 450
 451         /**
 452          * Turns on (false) or off (true) the automatic generation and sending
 453          * of a "we're sorry, but there has been a database error" page on
 454          * database errors. Default is on (false). When turned off, the
 455          * code should use lastErrno() and lastError() to handle the
 456          * situation as appropriate.
 457          *
 458          * Do not use this function outside of the Database classes.
 459          *
 460          * @param null|bool $ignoreErrors
 461          * @return bool The previous value of the flag.
 462          */
 463         protected function ignoreErrors( $ignoreErrors = null ) {
 464                 $res = $this->getFlag( self::DBO_IGNORE );
 465                 if ( $ignoreErrors !== null ) {
 466                         // setFlag()/clearFlag() do not allow DBO_IGNORE changes for sanity
 467                         if ( $ignoreErrors ) {
 468                                 $this->mFlags |= self::DBO_IGNORE;
 469                         } else {
 470                                 $this->mFlags &= ~self::DBO_IGNORE;
 471                         }
 472                 }
 473
 474                 return $res;
 475         }
 476
 477         public function trxLevel() {
 478                 return $this->mTrxLevel;
 479         }
 480
 481         public function trxTimestamp() {
 482                 return $this->mTrxLevel ? $this->mTrxTimestamp : null;
 483         }
 484
 485         public function tablePrefix( $prefix = null ) {
 486                 $old = $this->mTablePrefix;
 487                 if ( $prefix !== null ) {
 488                         $this->mTablePrefix = $prefix;
 489                         $this->currentDomain = ( $this->mDBname != '' )
 490                                 ? new DatabaseDomain( $this->mDBname, null, $this->mTablePrefix )
 491                                 : DatabaseDomain::newUnspecified();
 492                 }
 493
 494                 return $old;
 495         }
 496
 497         public function dbSchema( $schema = null ) {
 498                 $old = $this->mSchema;
 499                 if ( $schema !== null ) {
 500                         $this->mSchema = $schema;
 501                 }
 502
 503                 return $old;
 504         }
 505
 506         public function getLBInfo( $name = null ) {
 507                 if ( is_null( $name ) ) {
 508                         return $this->mLBInfo;
 509                 } else {
 510                         if ( array_key_exists( $name, $this->mLBInfo ) ) {
 511                                 return $this->mLBInfo[$name];
 512                         } else {
 513                                 return null;
 514                         }
 515                 }
 516         }
 517
 518         public function setLBInfo( $name, $value = null ) {
 519                 if ( is_null( $value ) ) {
 520                         $this->mLBInfo = $name;
 521                 } else {
 522                         $this->mLBInfo[$name] = $value;
 523                 }
 524         }
 525
 526         public function setLazyMasterHandle( IDatabase $conn ) {
 527                 $this->lazyMasterHandle = $conn;
 528         }
 529
 530         /**
 531          * @return IDatabase|null
 532          * @see setLazyMasterHandle()
 533          * @since 1.27
 534          */
 535         protected function getLazyMasterHandle() {
 536                 return $this->lazyMasterHandle;
 537         }
 538
 539         public function implicitGroupby() {
 540                 return true;
 541         }
 542
 543         public function implicitOrderby() {
 544                 return true;
 545         }
 546
 547         public function lastQuery() {
 548                 return $this->mLastQuery;
 549         }
 550
 551         public function doneWrites() {
 552                 return (bool)$this->mLastWriteTime;
 553         }
 554
 555         public function lastDoneWrites() {
 556                 return $this->mLastWriteTime ?: false;
 557         }
 558
 559         public function writesPending() {
 560                 return $this->mTrxLevel && $this->mTrxDoneWrites;
 561         }
 562
 563         public function writesOrCallbacksPending() {
 564                 return $this->mTrxLevel && (
 565                         $this->mTrxDoneWrites || $this->mTrxIdleCallbacks || $this->mTrxPreCommitCallbacks
 566                 );
 567         }
 568
 569         public function pendingWriteQueryDuration( $type = self::ESTIMATE_TOTAL ) {
 570                 if ( !$this->mTrxLevel ) {
 571                         return false;
 572                 } elseif ( !$this->mTrxDoneWrites ) {
 573                         return 0.0;
 574                 }
 575
 576                 switch ( $type ) {
 577                         case self::ESTIMATE_DB_APPLY:
 578                                 $this->ping( $rtt );
 579                                 $rttAdjTotal = $this->mTrxWriteAdjQueryCount * $rtt;
 580                                 $applyTime = max( $this->mTrxWriteAdjDuration - $rttAdjTotal, 0 );
 581                                 // For omitted queries, make them count as something at least
 582                                 $omitted = $this->mTrxWriteQueryCount - $this->mTrxWriteAdjQueryCount;
 583                                 $applyTime += self::TINY_WRITE_SEC * $omitted;
 584
 585                                 return $applyTime;
 586                         default: // everything
 587                                 return $this->mTrxWriteDuration;
 588                 }
 589         }
 590
 591         public function pendingWriteCallers() {
 592                 return $this->mTrxLevel ? $this->mTrxWriteCallers : [];
 593         }
 594
 595         public function pendingWriteRowsAffected() {
 596                 return $this->mTrxWriteAffectedRows;
 597         }
 598
 599         /**
 600          * Get the list of method names that have pending write queries or callbacks
 601          * for this transaction
 602          *
 603          * @return array
 604          */
 605         protected function pendingWriteAndCallbackCallers() {
 606                 if ( !$this->mTrxLevel ) {
 607                         return [];
 608                 }
 609
 610                 $fnames = $this->mTrxWriteCallers;
 611                 foreach ( [
 612                         $this->mTrxIdleCallbacks,
 613                         $this->mTrxPreCommitCallbacks,
 614                         $this->mTrxEndCallbacks
 615                 ] as $callbacks ) {
 616                         foreach ( $callbacks as $callback ) {
 617                                 $fnames[] = $callback[1];
 618                         }
 619                 }
 620
 621                 return $fnames;
 622         }
 623
 624         public function isOpen() {
 625                 return $this->mOpened;
 626         }
 627
 628         public function setFlag( $flag, $remember = self::REMEMBER_NOTHING ) {
 629                 if ( ( $flag & self::DBO_IGNORE ) ) {
 630                         throw new \UnexpectedValueException( "Modifying DBO_IGNORE is not allowed." );
 631                 }
 632
 633                 if ( $remember === self::REMEMBER_PRIOR ) {
 634                         array_push( $this->priorFlags, $this->mFlags );
 635                 }
 636                 $this->mFlags |= $flag;
 637         }
 638
 639         public function clearFlag( $flag, $remember = self::REMEMBER_NOTHING ) {
 640                 if ( ( $flag & self::DBO_IGNORE ) ) {
 641                         throw new \UnexpectedValueException( "Modifying DBO_IGNORE is not allowed." );
 642                 }
 643
 644                 if ( $remember === self::REMEMBER_PRIOR ) {
 645                         array_push( $this->priorFlags, $this->mFlags );
 646                 }
 647                 $this->mFlags &= ~$flag;
 648         }
 649
 650         public function restoreFlags( $state = self::RESTORE_PRIOR ) {
 651                 if ( !$this->priorFlags ) {
 652                         return;
 653                 }
 654
 655                 if ( $state === self::RESTORE_INITIAL ) {
 656                         $this->mFlags = reset( $this->priorFlags );
 657                         $this->priorFlags = [];
 658                 } else {
 659                         $this->mFlags = array_pop( $this->priorFlags );
 660                 }
 661         }
 662
 663         public function getFlag( $flag ) {
 664                 return !!( $this->mFlags & $flag );
 665         }
 666
 667         /**
 668          * @param string $name Class field name
 669          * @return mixed
 670          * @deprecated Since 1.28
 671          */
 672         public function getProperty( $name ) {
 673                 return $this->$name;
 674         }
 675
 676         public function getDomainID() {
 677                 return $this->currentDomain->getId();
 678         }
 679
 680         final public function getWikiID() {
 681                 return $this->getDomainID();
 682         }
 683
 684         /**
 685          * Get information about an index into an object
 686          * @param string $table Table name
 687          * @param string $index Index name
 688          * @param string $fname Calling function name
 689          * @return mixed Database-specific index description class or false if the index does not exist
 690          */
 691         abstract function indexInfo( $table, $index, $fname = __METHOD__ );
 692
 693         /**
 694          * Wrapper for addslashes()
 695          *
 696          * @param string $s String to be slashed.
 697          * @return string Slashed string.
 698          */
 699         abstract function strencode( $s );
 700
 701         /**
 702          * Set a custom error handler for logging errors during database connection
 703          */
 704         protected function installErrorHandler() {
 705                 $this->mPHPError = false;
 706                 $this->htmlErrors = ini_set( 'html_errors', '0' );
 707                 set_error_handler( [ $this, 'connectionErrorLogger' ] );
 708         }
 709
 710         /**
 711          * Restore the previous error handler and return the last PHP error for this DB
 712          *
 713          * @return bool|string
 714          */
 715         protected function restoreErrorHandler() {
 716                 restore_error_handler();
 717                 if ( $this->htmlErrors !== false ) {
 718                         ini_set( 'html_errors', $this->htmlErrors );
 719                 }
 720
 721                 return $this->getLastPHPError();
 722         }
 723
 724         /**
 725          * @return string|bool Last PHP error for this DB (typically connection errors)
 726          */
 727         protected function getLastPHPError() {
 728                 if ( $this->mPHPError ) {
 729                         $error = preg_replace( '!\[<a.*</a>\]!', '', $this->mPHPError );
 730                         $error = preg_replace( '!^.*?:\s?(.*)$!', '$1', $error );
 731
 732                         return $error;
 733                 }
 734
 735                 return false;
 736         }
 737
 738         /**
 739          * Error handler for logging errors during database connection
 740          * This method should not be used outside of Database classes
 741          *
 742          * @param int $errno
 743          * @param string $errstr
 744          */
 745         public function connectionErrorLogger( $errno, $errstr ) {
 746                 $this->mPHPError = $errstr;
 747         }
 748
 749         /**
 750          * Create a log context to pass to PSR-3 logger functions.
 751          *
 752          * @param array $extras Additional data to add to context
 753          * @return array
 754          */
 755         protected function getLogContext( array $extras = [] ) {
 756                 return array_merge(
 757                         [
 758                                 'db_server' => $this->mServer,
 759                                 'db_name' => $this->mDBname,
 760                                 'db_user' => $this->mUser,
 761                         ],
 762                         $extras
 763                 );
 764         }
 765
 766         public function close() {
 767                 if ( $this->mConn ) {
 768                         if ( $this->trxLevel() ) {
 769                                 $this->commit( __METHOD__, self::FLUSHING_INTERNAL );
 770                         }
 771
 772                         $closed = $this->closeConnection();
 773                         $this->mConn = false;
 774                 } elseif (
 775                         $this->mTrxIdleCallbacks ||
 776                         $this->mTrxPreCommitCallbacks ||
 777                         $this->mTrxEndCallbacks
 778                 ) { // sanity
 779                         throw new RuntimeException( "Transaction callbacks still pending." );
 780                 } else {
 781                         $closed = true;
 782                 }
 783                 $this->mOpened = false;
 784
 785                 return $closed;
 786         }
 787
 788         /**
 789          * Make sure isOpen() returns true as a sanity check
 790          *
 791          * @throws DBUnexpectedError
 792          */
 793         protected function assertOpen() {
 794                 if ( !$this->isOpen() ) {
 795                         throw new DBUnexpectedError( $this, "DB connection was already closed." );
 796                 }
 797         }
 798
 799         /**
 800          * Closes underlying database connection
 801          * @since 1.20
 802          * @return bool Whether connection was closed successfully
 803          */
 804         abstract protected function closeConnection();
 805
 806         public function reportConnectionError( $error = 'Unknown error' ) {
 807                 $myError = $this->lastError();
 808                 if ( $myError ) {
 809                         $error = $myError;
 810                 }
 811
 812                 # New method
 813                 throw new DBConnectionError( $this, $error );
 814         }
 815
 816         /**
 817          * The DBMS-dependent part of query()
 818          *
 819          * @param string $sql SQL query.
 820          * @return ResultWrapper|bool Result object to feed to fetchObject,
 821          *   fetchRow, ...; or false on failure
 822          */
 823         abstract protected function doQuery( $sql );
 824
 825         /**
 826          * Determine whether a query writes to the DB.
 827          * Should return true if unsure.
 828          *
 829          * @param string $sql
 830          * @return bool
 831          */
 832         protected function isWriteQuery( $sql ) {
 833                 return !preg_match(
 834                         '/^(?:SELECT|BEGIN|ROLLBACK|COMMIT|SET|SHOW|EXPLAIN|\(SELECT)\b/i', $sql );
 835         }
 836
 837         /**
 838          * @param string $sql
 839          * @return string|null
 840          */
 841         protected function getQueryVerb( $sql ) {
 842                 return preg_match( '/^\s*([a-z]+)/i', $sql, $m ) ? strtoupper( $m[1] ) : null;
 843         }
 844
 845         /**
 846          * Determine whether a SQL statement is sensitive to isolation level.
 847          * A SQL statement is considered transactable if its result could vary
 848          * depending on the transaction isolation level. Operational commands
 849          * such as 'SET' and 'SHOW' are not considered to be transactable.
 850          *
 851          * @param string $sql
 852          * @return bool
 853          */
 854         protected function isTransactableQuery( $sql ) {
 855                 return !in_array(
 856                         $this->getQueryVerb( $sql ),
 857                         [ 'BEGIN', 'COMMIT', 'ROLLBACK', 'SHOW', 'SET', 'CREATE', 'ALTER' ],
 858                         true
 859                 );
 860         }
 861
 862         /**
 863          * @param string $sql A SQL query
 864          * @return bool Whether $sql is SQL for TEMPORARY table operation
 865          */
 866         protected function registerTempTableOperation( $sql ) {
 867                 if ( preg_match(
 868                         '/^CREATE\s+TEMPORARY\s+TABLE\s+(?:IF\s+NOT\s+EXISTS\s+)?[`"\']?(\w+)[`"\']?/i',
 869                         $sql,
 870                         $matches
 871                 ) ) {
 872                         $this->mSessionTempTables[$matches[1]] = 1;
 873
 874                         return true;
 875                 } elseif ( preg_match(
 876                         '/^DROP\s+(?:TEMPORARY\s+)?TABLE\s+(?:IF\s+EXISTS\s+)?[`"\']?(\w+)[`"\']?/i',
 877                         $sql,
 878                         $matches
 879                 ) ) {
 880                         $isTemp = isset( $this->mSessionTempTables[$matches[1]] );
 881                         unset( $this->mSessionTempTables[$matches[1]] );
 882
 883                         return $isTemp;
 884                 } elseif ( preg_match(
 885                         '/^TRUNCATE\s+(?:TEMPORARY\s+)?TABLE\s+(?:IF\s+EXISTS\s+)?[`"\']?(\w+)[`"\']?/i',
 886                         $sql,
 887                         $matches
 888                 ) ) {
 889                         return isset( $this->mSessionTempTables[$matches[1]] );
 890                 } elseif ( preg_match(
 891                         '/^(?:INSERT\s+(?:\w+\s+)?INTO|UPDATE|DELETE\s+FROM)\s+[`"\']?(\w+)[`"\']?/i',
 892                         $sql,
 893                         $matches
 894                 ) ) {
 895                         return isset( $this->mSessionTempTables[$matches[1]] );
 896                 }
 897
 898                 return false;
 899         }
 900
 901         public function query( $sql, $fname = __METHOD__, $tempIgnore = false ) {
 902                 $priorWritesPending = $this->writesOrCallbacksPending();
 903                 $this->mLastQuery = $sql;
 904
 905                 $isWrite = $this->isWriteQuery( $sql );
 906                 if ( $isWrite ) {
 907                         $isNonTempWrite = !$this->registerTempTableOperation( $sql );
 908                 } else {
 909                         $isNonTempWrite = false;
 910                 }
 911
 912                 if ( $isWrite ) {
 913                         if ( $this->getLBInfo( 'replica' ) === true ) {
 914                                 throw new DBError(
 915                                         $this,
 916                                         'Write operations are not allowed on replica database connections.'
 917                                 );
 918                         }
 919                         # In theory, non-persistent writes are allowed in read-only mode, but due to things
 920                         # like https://bugs.mysql.com/bug.php?id=33669 that might not work anyway...
 921                         $reason = $this->getReadOnlyReason();
 922                         if ( $reason !== false ) {
 923                                 throw new DBReadOnlyError( $this, "Database is read-only: $reason" );
 924                         }
 925                         # Set a flag indicating that writes have been done
 926                         $this->mLastWriteTime = microtime( true );
 927                 }
 928
 929                 # Add trace comment to the begin of the sql string, right after the operator.
 930                 # Or, for one-word queries (like "BEGIN" or COMMIT") add it to the end (T44598)
 931                 $commentedSql = preg_replace( '/\s|$/', " /* $fname {$this->agent} */ ", $sql, 1 );
 932
 933                 # Start implicit transactions that wrap the request if DBO_TRX is enabled
 934                 if ( !$this->mTrxLevel && $this->getFlag( self::DBO_TRX )
 935                         && $this->isTransactableQuery( $sql )
 936                 ) {
 937                         $this->begin( __METHOD__ . " ($fname)", self::TRANSACTION_INTERNAL );
 938                         $this->mTrxAutomatic = true;
 939                 }
 940
 941                 # Keep track of whether the transaction has write queries pending
 942                 if ( $this->mTrxLevel && !$this->mTrxDoneWrites && $isWrite ) {
 943                         $this->mTrxDoneWrites = true;
 944                         $this->trxProfiler->transactionWritingIn(
 945                                 $this->mServer, $this->mDBname, $this->mTrxShortId );
 946                 }
 947
 948                 if ( $this->getFlag( self::DBO_DEBUG ) ) {
 949                         $this->queryLogger->debug( "{$this->mDBname} {$commentedSql}" );
 950                 }
 951
 952                 # Avoid fatals if close() was called
 953                 $this->assertOpen();
 954
 955                 # Send the query to the server
 956                 $ret = $this->doProfiledQuery( $sql, $commentedSql, $isNonTempWrite, $fname );
 957
 958                 # Try reconnecting if the connection was lost
 959                 if ( false === $ret && $this->wasErrorReissuable() ) {
 960                         $recoverable = $this->canRecoverFromDisconnect( $sql, $priorWritesPending );
 961                         # Stash the last error values before anything might clear them
 962                         $lastError = $this->lastError();
 963                         $lastErrno = $this->lastErrno();
 964                         # Update state tracking to reflect transaction loss due to disconnection
 965                         $this->handleSessionLoss();
 966                         if ( $this->reconnect() ) {
 967                                 $msg = __METHOD__ . ': lost connection to {dbserver}; reconnected';
 968                                 $params = [ 'dbserver' => $this->getServer() ];
 969                                 $this->connLogger->warning( $msg, $params );
 970                                 $this->queryLogger->warning( $msg, $params +
 971                                         [ 'trace' => ( new RuntimeException() )->getTraceAsString() ] );
 972
 973                                 if ( !$recoverable ) {
 974                                         # Callers may catch the exception and continue to use the DB
 975                                         $this->reportQueryError( $lastError, $lastErrno, $sql, $fname );
 976                                 } else {
 977                                         # Should be safe to silently retry the query
 978                                         $ret = $this->doProfiledQuery( $sql, $commentedSql, $isNonTempWrite, $fname );
 979                                 }
 980                         } else {
 981                                 $msg = __METHOD__ . ': lost connection to {dbserver} permanently';
 982                                 $this->connLogger->error( $msg, [ 'dbserver' => $this->getServer() ] );
 983                         }
 984                 }
 985
 986                 if ( false === $ret ) {
 987                         # Deadlocks cause the entire transaction to abort, not just the statement.
 988                         # https://dev.mysql.com/doc/refman/5.7/en/innodb-error-handling.html
 989                         # https://www.postgresql.org/docs/9.1/static/explicit-locking.html
 990                         if ( $this->wasDeadlock() ) {
 991                                 if ( $this->explicitTrxActive() || $priorWritesPending ) {
 992                                         $tempIgnore = false; // not recoverable
 993                                 }
 994                                 # Update state tracking to reflect transaction loss
 995                                 $this->handleSessionLoss();
 996                         }
 997
 998                         $this->reportQueryError(
 999                                 $this->lastError(), $this->lastErrno(), $sql, $fname, $tempIgnore );
1000                 }
1001
1002                 $res = $this->resultObject( $ret );
1003
1004                 return $res;
1005         }
1006
1007         /**
1008          * Helper method for query() that handles profiling and logging and sends
1009          * the query to doQuery()
1010          *
1011          * @param string $sql Original SQL query
1012          * @param string $commentedSql SQL query with debugging/trace comment
1013          * @param bool $isWrite Whether the query is a (non-temporary) write operation
1014          * @param string $fname Name of the calling function
1015          * @return bool|ResultWrapper True for a successful write query, ResultWrapper
1016          *     object for a successful read query, or false on failure
1017          */
1018         private function doProfiledQuery( $sql, $commentedSql, $isWrite, $fname ) {
1019                 $isMaster = !is_null( $this->getLBInfo( 'master' ) );
1020                 # generalizeSQL() will probably cut down the query to reasonable
1021                 # logging size most of the time. The substr is really just a sanity check.
1022                 if ( $isMaster ) {
1023                         $queryProf = 'query-m: ' . substr( self::generalizeSQL( $sql ), 0, 255 );
1024                 } else {
1025                         $queryProf = 'query: ' . substr( self::generalizeSQL( $sql ), 0, 255 );
1026                 }
1027
1028                 # Include query transaction state
1029                 $queryProf .= $this->mTrxShortId ? " [TRX#{$this->mTrxShortId}]" : "";
1030
1031                 $startTime = microtime( true );
1032                 if ( $this->profiler ) {
1033                         call_user_func( [ $this->profiler, 'profileIn' ], $queryProf );
1034                 }
1035                 $ret = $this->doQuery( $commentedSql );
1036                 if ( $this->profiler ) {
1037                         call_user_func( [ $this->profiler, 'profileOut' ], $queryProf );
1038                 }
1039                 $queryRuntime = max( microtime( true ) - $startTime, 0.0 );
1040
1041                 unset( $queryProfSection ); // profile out (if set)
1042
1043                 if ( $ret !== false ) {
1044                         $this->lastPing = $startTime;
1045                         if ( $isWrite && $this->mTrxLevel ) {
1046                                 $this->updateTrxWriteQueryTime( $sql, $queryRuntime, $this->affectedRows() );
1047                                 $this->mTrxWriteCallers[] = $fname;
1048                         }
1049                 }
1050
1051                 if ( $sql === self::PING_QUERY ) {
1052                         $this->mRTTEstimate = $queryRuntime;
1053                 }
1054
1055                 $this->trxProfiler->recordQueryCompletion(
1056                         $queryProf, $startTime, $isWrite, $this->affectedRows()
1057                 );
1058                 $this->queryLogger->debug( $sql, [
1059                         'method' => $fname,
1060                         'master' => $isMaster,
1061                         'runtime' => $queryRuntime,
1062                 ] );
1063
1064                 return $ret;
1065         }
1066
1067         /**
1068          * Update the estimated run-time of a query, not counting large row lock times
1069          *
1070          * LoadBalancer can be set to rollback transactions that will create huge replication
1071          * lag. It bases this estimate off of pendingWriteQueryDuration(). Certain simple
1072          * queries, like inserting a row can take a long time due to row locking. This method
1073          * uses some simple heuristics to discount those cases.
1074          *
1075          * @param string $sql A SQL write query
1076          * @param float $runtime Total runtime, including RTT
1077          * @param int $affected Affected row count
1078          */
1079         private function updateTrxWriteQueryTime( $sql, $runtime, $affected ) {
1080                 // Whether this is indicative of replica DB runtime (except for RBR or ws_repl)
1081                 $indicativeOfReplicaRuntime = true;
1082                 if ( $runtime > self::SLOW_WRITE_SEC ) {
1083                         $verb = $this->getQueryVerb( $sql );
1084                         // insert(), upsert(), replace() are fast unless bulky in size or blocked on locks
1085                         if ( $verb === 'INSERT' ) {
1086                                 $indicativeOfReplicaRuntime = $this->affectedRows() > self::SMALL_WRITE_ROWS;
1087                         } elseif ( $verb === 'REPLACE' ) {
1088                                 $indicativeOfReplicaRuntime = $this->affectedRows() > self::SMALL_WRITE_ROWS / 2;
1089                         }
1090                 }
1091
1092                 $this->mTrxWriteDuration += $runtime;
1093                 $this->mTrxWriteQueryCount += 1;
1094                 $this->mTrxWriteAffectedRows += $affected;
1095                 if ( $indicativeOfReplicaRuntime ) {
1096                         $this->mTrxWriteAdjDuration += $runtime;
1097                         $this->mTrxWriteAdjQueryCount += 1;
1098                 }
1099         }
1100
1101         /**
1102          * Determine whether or not it is safe to retry queries after a database
1103          * connection is lost
1104          *
1105          * @param string $sql SQL query
1106          * @param bool $priorWritesPending Whether there is a transaction open with
1107          *     possible write queries or transaction pre-commit/idle callbacks
1108          *     waiting on it to finish.
1109          * @return bool True if it is safe to retry the query, false otherwise
1110          */
1111         private function canRecoverFromDisconnect( $sql, $priorWritesPending ) {
1112                 # Transaction dropped; this can mean lost writes, or REPEATABLE-READ snapshots.
1113                 # Dropped connections also mean that named locks are automatically released.
1114                 # Only allow error suppression in autocommit mode or when the lost transaction
1115                 # didn't matter anyway (aside from DBO_TRX snapshot loss).
1116                 if ( $this->mNamedLocksHeld ) {
1117                         return false; // possible critical section violation
1118                 } elseif ( $sql === 'COMMIT' ) {
1119                         return !$priorWritesPending; // nothing written anyway? (T127428)
1120                 } elseif ( $sql === 'ROLLBACK' ) {
1121                         return true; // transaction lost...which is also what was requested :)
1122                 } elseif ( $this->explicitTrxActive() ) {
1123                         return false; // don't drop atomocity
1124                 } elseif ( $priorWritesPending ) {
1125                         return false; // prior writes lost from implicit transaction
1126                 }
1127
1128                 return true;
1129         }
1130
1131         /**
1132          * Clean things up after transaction loss due to disconnection
1133          *
1134          * @return null|Exception
1135          */
1136         private function handleSessionLoss() {
1137                 $this->mTrxLevel = 0;
1138                 $this->mTrxIdleCallbacks = []; // T67263
1139                 $this->mTrxPreCommitCallbacks = []; // T67263
1140                 $this->mSessionTempTables = [];
1141                 $this->mNamedLocksHeld = [];
1142                 try {
1143                         // Handle callbacks in mTrxEndCallbacks
1144                         $this->runOnTransactionIdleCallbacks( self::TRIGGER_ROLLBACK );
1145                         $this->runTransactionListenerCallbacks( self::TRIGGER_ROLLBACK );
1146                         return null;
1147                 } catch ( Exception $e ) {
1148                         // Already logged; move on...
1149                         return $e;
1150                 }
1151         }
1152
1153         /**
1154          * Checks whether the cause of the error is detected to be a timeout.
1155          *
1156          * It returns false by default, and not all engines support detecting this yet.
1157          * If this returns false, it will be treated as a generic query error.
1158          *
1159          * @param string $error Error text
1160          * @param int $errno Error number
1161          * @return bool
1162          */
1163         protected function wasQueryTimeout( $error, $errno ) {
1164                 return false;
1165         }
1166
1167         public function reportQueryError( $error, $errno, $sql, $fname, $tempIgnore = false ) {
1168                 if ( $this->ignoreErrors() || $tempIgnore ) {
1169                         $this->queryLogger->debug( "SQL ERROR (ignored): $error\n" );
1170                 } else {
1171                         $sql1line = mb_substr( str_replace( "\n", "\\n", $sql ), 0, 5 * 1024 );
1172                         $this->queryLogger->error(
1173                                 "{fname}\t{db_server}\t{errno}\t{error}\t{sql1line}",
1174                                 $this->getLogContext( [
1175                                         'method' => __METHOD__,
1176                                         'errno' => $errno,
1177                                         'error' => $error,
1178                                         'sql1line' => $sql1line,
1179                                         'fname' => $fname,
1180                                 ] )
1181                         );
1182                         $this->queryLogger->debug( "SQL ERROR: " . $error . "\n" );
1183                         $wasQueryTimeout = $this->wasQueryTimeout( $error, $errno );
1184                         if ( $wasQueryTimeout ) {
1185                                 throw new DBQueryTimeoutError( $this, $error, $errno, $sql, $fname );
1186                         } else {
1187                                 throw new DBQueryError( $this, $error, $errno, $sql, $fname );
1188                         }
1189                 }
1190         }
1191
1192         public function freeResult( $res ) {
1193         }
1194
1195         public function selectField(
1196                 $table, $var, $cond = '', $fname = __METHOD__, $options = [], $join_conds = []
1197         ) {
1198                 if ( $var === '*' ) { // sanity
1199                         throw new DBUnexpectedError( $this, "Cannot use a * field: got '$var'" );
1200                 }
1201
1202                 if ( !is_array( $options ) ) {
1203                         $options = [ $options ];
1204                 }
1205
1206                 $options['LIMIT'] = 1;
1207
1208                 $res = $this->select( $table, $var, $cond, $fname, $options, $join_conds );
1209                 if ( $res === false || !$this->numRows( $res ) ) {
1210                         return false;
1211                 }
1212
1213                 $row = $this->fetchRow( $res );
1214
1215                 if ( $row !== false ) {
1216                         return reset( $row );
1217                 } else {
1218                         return false;
1219                 }
1220         }
1221
1222         public function selectFieldValues(
1223                 $table, $var, $cond = '', $fname = __METHOD__, $options = [], $join_conds = []
1224         ) {
1225                 if ( $var === '*' ) { // sanity
1226                         throw new DBUnexpectedError( $this, "Cannot use a * field" );
1227                 } elseif ( !is_string( $var ) ) { // sanity
1228                         throw new DBUnexpectedError( $this, "Cannot use an array of fields" );
1229                 }
1230
1231                 if ( !is_array( $options ) ) {
1232                         $options = [ $options ];
1233                 }
1234
1235                 $res = $this->select( $table, $var, $cond, $fname, $options, $join_conds );
1236                 if ( $res === false ) {
1237                         return false;
1238                 }
1239
1240                 $values = [];
1241                 foreach ( $res as $row ) {
1242                         $values[] = $row->$var;
1243                 }
1244
1245                 return $values;
1246         }
1247
1248         /**
1249          * Returns an optional USE INDEX clause to go after the table, and a
1250          * string to go at the end of the query.
1251          *
1252          * @param array $options Associative array of options to be turned into
1253          *   an SQL query, valid keys are listed in the function.
1254          * @return array
1255          * @see Database::select()
1256          */
1257         protected function makeSelectOptions( $options ) {
1258                 $preLimitTail = $postLimitTail = '';
1259                 $startOpts = '';
1260
1261                 $noKeyOptions = [];
1262
1263                 foreach ( $options as $key => $option ) {
1264                         if ( is_numeric( $key ) ) {
1265                                 $noKeyOptions[$option] = true;
1266                         }
1267                 }
1268
1269                 $preLimitTail .= $this->makeGroupByWithHaving( $options );
1270
1271                 $preLimitTail .= $this->makeOrderBy( $options );
1272
1273                 if ( isset( $noKeyOptions['FOR UPDATE'] ) ) {
1274                         $postLimitTail .= ' FOR UPDATE';
1275                 }
1276
1277                 if ( isset( $noKeyOptions['LOCK IN SHARE MODE'] ) ) {
1278                         $postLimitTail .= ' LOCK IN SHARE MODE';
1279                 }
1280
1281                 if ( isset( $noKeyOptions['DISTINCT'] ) || isset( $noKeyOptions['DISTINCTROW'] ) ) {
1282                         $startOpts .= 'DISTINCT';
1283                 }
1284
1285                 # Various MySQL extensions
1286                 if ( isset( $noKeyOptions['STRAIGHT_JOIN'] ) ) {
1287                         $startOpts .= ' /*! STRAIGHT_JOIN */';
1288                 }
1289
1290                 if ( isset( $noKeyOptions['HIGH_PRIORITY'] ) ) {
1291                         $startOpts .= ' HIGH_PRIORITY';
1292                 }
1293
1294                 if ( isset( $noKeyOptions['SQL_BIG_RESULT'] ) ) {
1295                         $startOpts .= ' SQL_BIG_RESULT';
1296                 }
1297
1298                 if ( isset( $noKeyOptions['SQL_BUFFER_RESULT'] ) ) {
1299                         $startOpts .= ' SQL_BUFFER_RESULT';
1300                 }
1301
1302                 if ( isset( $noKeyOptions['SQL_SMALL_RESULT'] ) ) {
1303                         $startOpts .= ' SQL_SMALL_RESULT';
1304                 }
1305
1306                 if ( isset( $noKeyOptions['SQL_CALC_FOUND_ROWS'] ) ) {
1307                         $startOpts .= ' SQL_CALC_FOUND_ROWS';
1308                 }
1309
1310                 if ( isset( $noKeyOptions['SQL_CACHE'] ) ) {
1311                         $startOpts .= ' SQL_CACHE';
1312                 }
1313
1314                 if ( isset( $noKeyOptions['SQL_NO_CACHE'] ) ) {
1315                         $startOpts .= ' SQL_NO_CACHE';
1316                 }
1317
1318                 if ( isset( $options['USE INDEX'] ) && is_string( $options['USE INDEX'] ) ) {
1319                         $useIndex = $this->useIndexClause( $options['USE INDEX'] );
1320                 } else {
1321                         $useIndex = '';
1322                 }
1323                 if ( isset( $options['IGNORE INDEX'] ) && is_string( $options['IGNORE INDEX'] ) ) {
1324                         $ignoreIndex = $this->ignoreIndexClause( $options['IGNORE INDEX'] );
1325                 } else {
1326                         $ignoreIndex = '';
1327                 }
1328
1329                 return [ $startOpts, $useIndex, $preLimitTail, $postLimitTail, $ignoreIndex ];
1330         }
1331
1332         /**
1333          * Returns an optional GROUP BY with an optional HAVING
1334          *
1335          * @param array $options Associative array of options
1336          * @return string
1337          * @see Database::select()
1338          * @since 1.21
1339          */
1340         protected function makeGroupByWithHaving( $options ) {
1341                 $sql = '';
1342                 if ( isset( $options['GROUP BY'] ) ) {
1343                         $gb = is_array( $options['GROUP BY'] )
1344                                 ? implode( ',', $options['GROUP BY'] )
1345                                 : $options['GROUP BY'];
1346                         $sql .= ' GROUP BY ' . $gb;
1347                 }
1348                 if ( isset( $options['HAVING'] ) ) {
1349                         $having = is_array( $options['HAVING'] )
1350                                 ? $this->makeList( $options['HAVING'], self::LIST_AND )
1351                                 : $options['HAVING'];
1352                         $sql .= ' HAVING ' . $having;
1353                 }
1354
1355                 return $sql;
1356         }
1357
1358         /**
1359          * Returns an optional ORDER BY
1360          *
1361          * @param array $options Associative array of options
1362          * @return string
1363          * @see Database::select()
1364          * @since 1.21
1365          */
1366         protected function makeOrderBy( $options ) {
1367                 if ( isset( $options['ORDER BY'] ) ) {
1368                         $ob = is_array( $options['ORDER BY'] )
1369                                 ? implode( ',', $options['ORDER BY'] )
1370                                 : $options['ORDER BY'];
1371
1372                         return ' ORDER BY ' . $ob;
1373                 }
1374
1375                 return '';
1376         }
1377
1378         public function select( $table, $vars, $conds = '', $fname = __METHOD__,
1379                 $options = [], $join_conds = [] ) {
1380                 $sql = $this->selectSQLText( $table, $vars, $conds, $fname, $options, $join_conds );
1381
1382                 return $this->query( $sql, $fname );
1383         }
1384
1385         public function selectSQLText( $table, $vars, $conds = '', $fname = __METHOD__,
1386                 $options = [], $join_conds = []
1387         ) {
1388                 if ( is_array( $vars ) ) {
1389                         $vars = implode( ',', $this->fieldNamesWithAlias( $vars ) );
1390                 }
1391
1392                 $options = (array)$options;
1393                 $useIndexes = ( isset( $options['USE INDEX'] ) && is_array( $options['USE INDEX'] ) )
1394                         ? $options['USE INDEX']
1395                         : [];
1396                 $ignoreIndexes = (
1397                         isset( $options['IGNORE INDEX'] ) &&
1398                         is_array( $options['IGNORE INDEX'] )
1399                 )
1400                         ? $options['IGNORE INDEX']
1401                         : [];
1402
1403                 if ( is_array( $table ) ) {
1404                         $from = ' FROM ' .
1405                                 $this->tableNamesWithIndexClauseOrJOIN(
1406                                         $table, $useIndexes, $ignoreIndexes, $join_conds );
1407                 } elseif ( $table != '' ) {
1408                         if ( $table[0] == ' ' ) {
1409                                 $from = ' FROM ' . $table;
1410                         } else {
1411                                 $from = ' FROM ' .
1412                                         $this->tableNamesWithIndexClauseOrJOIN(
1413                                                 [ $table ], $useIndexes, $ignoreIndexes, [] );
1414                         }
1415                 } else {
1416                         $from = '';
1417                 }
1418
1419                 list( $startOpts, $useIndex, $preLimitTail, $postLimitTail, $ignoreIndex ) =
1420                         $this->makeSelectOptions( $options );
1421
1422                 if ( !empty( $conds ) ) {
1423                         if ( is_array( $conds ) ) {
1424                                 $conds = $this->makeList( $conds, self::LIST_AND );
1425                         }
1426                         $sql = "SELECT $startOpts $vars $from $useIndex $ignoreIndex " .
1427                                 "WHERE $conds $preLimitTail";
1428                 } else {
1429                         $sql = "SELECT $startOpts $vars $from $useIndex $ignoreIndex $preLimitTail";
1430                 }
1431
1432                 if ( isset( $options['LIMIT'] ) ) {
1433                         $sql = $this->limitResult( $sql, $options['LIMIT'],
1434                                 isset( $options['OFFSET'] ) ? $options['OFFSET'] : false );
1435                 }
1436                 $sql = "$sql $postLimitTail";
1437
1438                 if ( isset( $options['EXPLAIN'] ) ) {
1439                         $sql = 'EXPLAIN ' . $sql;
1440                 }
1441
1442                 return $sql;
1443         }
1444
1445         public function selectRow( $table, $vars, $conds, $fname = __METHOD__,
1446                 $options = [], $join_conds = []
1447         ) {
1448                 $options = (array)$options;
1449                 $options['LIMIT'] = 1;
1450                 $res = $this->select( $table, $vars, $conds, $fname, $options, $join_conds );
1451
1452                 if ( $res === false ) {
1453                         return false;
1454                 }
1455
1456                 if ( !$this->numRows( $res ) ) {
1457                         return false;
1458                 }
1459
1460                 $obj = $this->fetchObject( $res );
1461
1462                 return $obj;
1463         }
1464
1465         public function estimateRowCount(
1466                 $table, $vars = '*', $conds = '', $fname = __METHOD__, $options = []
1467         ) {
1468                 $rows = 0;
1469                 $res = $this->select( $table, [ 'rowcount' => 'COUNT(*)' ], $conds, $fname, $options );
1470
1471                 if ( $res ) {
1472                         $row = $this->fetchRow( $res );
1473                         $rows = ( isset( $row['rowcount'] ) ) ? (int)$row['rowcount'] : 0;
1474                 }
1475
1476                 return $rows;
1477         }
1478
1479         public function selectRowCount(
1480                 $tables, $vars = '*', $conds = '', $fname = __METHOD__, $options = [], $join_conds = []
1481         ) {
1482                 $rows = 0;
1483                 $sql = $this->selectSQLText( $tables, '1', $conds, $fname, $options, $join_conds );
1484                 // The identifier quotes is primarily for MSSQL.
1485                 $rowCountCol = $this->addIdentifierQuotes( "rowcount" );
1486                 $tableName = $this->addIdentifierQuotes( "tmp_count" );
1487                 $res = $this->query( "SELECT COUNT(*) AS $rowCountCol FROM ($sql) $tableName", $fname );
1488
1489                 if ( $res ) {
1490                         $row = $this->fetchRow( $res );
1491                         $rows = ( isset( $row['rowcount'] ) ) ? (int)$row['rowcount'] : 0;
1492                 }
1493
1494                 return $rows;
1495         }
1496
1497         /**
1498          * Removes most variables from an SQL query and replaces them with X or N for numbers.
1499          * It's only slightly flawed. Don't use for anything important.
1500          *
1501          * @param string $sql A SQL Query
1502          *
1503          * @return string
1504          */
1505         protected static function generalizeSQL( $sql ) {
1506                 # This does the same as the regexp below would do, but in such a way
1507                 # as to avoid crashing php on some large strings.
1508                 # $sql = preg_replace( "/'([^\\\\']|\\\\.)*'|\"([^\\\\\"]|\\\\.)*\"/", "'X'", $sql );
1509
1510                 $sql = str_replace( "\\\\", '', $sql );
1511                 $sql = str_replace( "\\'", '', $sql );
1512                 $sql = str_replace( "\\\"", '', $sql );
1513                 $sql = preg_replace( "/'.*'/s", "'X'", $sql );
1514                 $sql = preg_replace( '/".*"/s', "'X'", $sql );
1515
1516                 # All newlines, tabs, etc replaced by single space
1517                 $sql = preg_replace( '/\s+/', ' ', $sql );
1518
1519                 # All numbers => N,
1520                 # except the ones surrounded by characters, e.g. l10n
1521                 $sql = preg_replace( '/-?\d+(,-?\d+)+/s', 'N,...,N', $sql );
1522                 $sql = preg_replace( '/(?<![a-zA-Z])-?\d+(?![a-zA-Z])/s', 'N', $sql );
1523
1524                 return $sql;
1525         }
1526
1527         public function fieldExists( $table, $field, $fname = __METHOD__ ) {
1528                 $info = $this->fieldInfo( $table, $field );
1529
1530                 return (bool)$info;
1531         }
1532
1533         public function indexExists( $table, $index, $fname = __METHOD__ ) {
1534                 if ( !$this->tableExists( $table ) ) {
1535                         return null;
1536                 }
1537
1538                 $info = $this->indexInfo( $table, $index, $fname );
1539                 if ( is_null( $info ) ) {
1540                         return null;
1541                 } else {
1542                         return $info !== false;
1543                 }
1544         }
1545
1546         public function tableExists( $table, $fname = __METHOD__ ) {
1547                 $tableRaw = $this->tableName( $table, 'raw' );
1548                 if ( isset( $this->mSessionTempTables[$tableRaw] ) ) {
1549                         return true; // already known to exist
1550                 }
1551
1552                 $table = $this->tableName( $table );
1553                 $ignoreErrors = true;
1554                 $res = $this->query( "SELECT 1 FROM $table LIMIT 1", $fname, $ignoreErrors );
1555
1556                 return (bool)$res;
1557         }
1558
1559         public function indexUnique( $table, $index ) {
1560                 $indexInfo = $this->indexInfo( $table, $index );
1561
1562                 if ( !$indexInfo ) {
1563                         return null;
1564                 }
1565
1566                 return !$indexInfo[0]->Non_unique;
1567         }
1568
1569         /**
1570          * Helper for Database::insert().
1571          *
1572          * @param array $options
1573          * @return string
1574          */
1575         protected function makeInsertOptions( $options ) {
1576                 return implode( ' ', $options );
1577         }
1578
1579         public function insert( $table, $a, $fname = __METHOD__, $options = [] ) {
1580                 # No rows to insert, easy just return now
1581                 if ( !count( $a ) ) {
1582                         return true;
1583                 }
1584
1585                 $table = $this->tableName( $table );
1586
1587                 if ( !is_array( $options ) ) {
1588                         $options = [ $options ];
1589                 }
1590
1591                 $fh = null;
1592                 if ( isset( $options['fileHandle'] ) ) {
1593                         $fh = $options['fileHandle'];
1594                 }
1595                 $options = $this->makeInsertOptions( $options );
1596
1597                 if ( isset( $a[0] ) && is_array( $a[0] ) ) {
1598                         $multi = true;
1599                         $keys = array_keys( $a[0] );
1600                 } else {
1601                         $multi = false;
1602                         $keys = array_keys( $a );
1603                 }
1604
1605                 $sql = 'INSERT ' . $options .
1606                         " INTO $table (" . implode( ',', $keys ) . ') VALUES ';
1607
1608                 if ( $multi ) {
1609                         $first = true;
1610                         foreach ( $a as $row ) {
1611                                 if ( $first ) {
1612                                         $first = false;
1613                                 } else {
1614                                         $sql .= ',';
1615                                 }
1616                                 $sql .= '(' . $this->makeList( $row ) . ')';
1617                         }
1618                 } else {
1619                         $sql .= '(' . $this->makeList( $a ) . ')';
1620                 }
1621
1622                 if ( $fh !== null && false === fwrite( $fh, $sql ) ) {
1623                         return false;
1624                 } elseif ( $fh !== null ) {
1625                         return true;
1626                 }
1627
1628                 return (bool)$this->query( $sql, $fname );
1629         }
1630
1631         /**
1632          * Make UPDATE options array for Database::makeUpdateOptions
1633          *
1634          * @param array $options
1635          * @return array
1636          */
1637         protected function makeUpdateOptionsArray( $options ) {
1638                 if ( !is_array( $options ) ) {
1639                         $options = [ $options ];
1640                 }
1641
1642                 $opts = [];
1643
1644                 if ( in_array( 'IGNORE', $options ) ) {
1645                         $opts[] = 'IGNORE';
1646                 }
1647
1648                 return $opts;
1649         }
1650
1651         /**
1652          * Make UPDATE options for the Database::update function
1653          *
1654          * @param array $options The options passed to Database::update
1655          * @return string
1656          */
1657         protected function makeUpdateOptions( $options ) {
1658                 $opts = $this->makeUpdateOptionsArray( $options );
1659
1660                 return implode( ' ', $opts );
1661         }
1662
1663         public function update( $table, $values, $conds, $fname = __METHOD__, $options = [] ) {
1664                 $table = $this->tableName( $table );
1665                 $opts = $this->makeUpdateOptions( $options );
1666                 $sql = "UPDATE $opts $table SET " . $this->makeList( $values, self::LIST_SET );
1667
1668                 if ( $conds !== [] && $conds !== '*' ) {
1669                         $sql .= " WHERE " . $this->makeList( $conds, self::LIST_AND );
1670                 }
1671
1672                 return (bool)$this->query( $sql, $fname );
1673         }
1674
1675         public function makeList( $a, $mode = self::LIST_COMMA ) {
1676                 if ( !is_array( $a ) ) {
1677                         throw new DBUnexpectedError( $this, __METHOD__ . ' called with incorrect parameters' );
1678                 }
1679
1680                 $first = true;
1681                 $list = '';
1682
1683                 foreach ( $a as $field => $value ) {
1684                         if ( !$first ) {
1685                                 if ( $mode == self::LIST_AND ) {
1686                                         $list .= ' AND ';
1687                                 } elseif ( $mode == self::LIST_OR ) {
1688                                         $list .= ' OR ';
1689                                 } else {
1690                                         $list .= ',';
1691                                 }
1692                         } else {
1693                                 $first = false;
1694                         }
1695
1696                         if ( ( $mode == self::LIST_AND || $mode == self::LIST_OR ) && is_numeric( $field ) ) {
1697                                 $list .= "($value)";
1698                         } elseif ( $mode == self::LIST_SET && is_numeric( $field ) ) {
1699                                 $list .= "$value";
1700                         } elseif (
1701                                 ( $mode == self::LIST_AND || $mode == self::LIST_OR ) && is_array( $value )
1702                         ) {
1703                                 // Remove null from array to be handled separately if found
1704                                 $includeNull = false;
1705                                 foreach ( array_keys( $value, null, true ) as $nullKey ) {
1706                                         $includeNull = true;
1707                                         unset( $value[$nullKey] );
1708                                 }
1709                                 if ( count( $value ) == 0 && !$includeNull ) {
1710                                         throw new InvalidArgumentException(
1711                                                 __METHOD__ . ": empty input for field $field" );
1712                                 } elseif ( count( $value ) == 0 ) {
1713                                         // only check if $field is null
1714                                         $list .= "$field IS NULL";
1715                                 } else {
1716                                         // IN clause contains at least one valid element
1717                                         if ( $includeNull ) {
1718                                                 // Group subconditions to ensure correct precedence
1719                                                 $list .= '(';
1720                                         }
1721                                         if ( count( $value ) == 1 ) {
1722                                                 // Special-case single values, as IN isn't terribly efficient
1723                                                 // Don't necessarily assume the single key is 0; we don't
1724                                                 // enforce linear numeric ordering on other arrays here.
1725                                                 $value = array_values( $value )[0];
1726                                                 $list .= $field . " = " . $this->addQuotes( $value );
1727                                         } else {
1728                                                 $list .= $field . " IN (" . $this->makeList( $value ) . ") ";
1729                                         }
1730                                         // if null present in array, append IS NULL
1731                                         if ( $includeNull ) {
1732                                                 $list .= " OR $field IS NULL)";
1733                                         }
1734                                 }
1735                         } elseif ( $value === null ) {
1736                                 if ( $mode == self::LIST_AND || $mode == self::LIST_OR ) {
1737                                         $list .= "$field IS ";
1738                                 } elseif ( $mode == self::LIST_SET ) {
1739                                         $list .= "$field = ";
1740                                 }
1741                                 $list .= 'NULL';
1742                         } else {
1743                                 if (
1744                                         $mode == self::LIST_AND || $mode == self::LIST_OR || $mode == self::LIST_SET
1745                                 ) {
1746                                         $list .= "$field = ";
1747                                 }
1748                                 $list .= $mode == self::LIST_NAMES ? $value : $this->addQuotes( $value );
1749                         }
1750                 }
1751
1752                 return $list;
1753         }
1754
1755         public function makeWhereFrom2d( $data, $baseKey, $subKey ) {
1756                 $conds = [];
1757
1758                 foreach ( $data as $base => $sub ) {
1759                         if ( count( $sub ) ) {
1760                                 $conds[] = $this->makeList(
1761                                         [ $baseKey => $base, $subKey => array_keys( $sub ) ],
1762                                         self::LIST_AND );
1763                         }
1764                 }
1765
1766                 if ( $conds ) {
1767                         return $this->makeList( $conds, self::LIST_OR );
1768                 } else {
1769                         // Nothing to search for...
1770                         return false;
1771                 }
1772         }
1773
1774         public function aggregateValue( $valuedata, $valuename = 'value' ) {
1775                 return $valuename;
1776         }
1777
1778         public function bitNot( $field ) {
1779                 return "(~$field)";
1780         }
1781
1782         public function bitAnd( $fieldLeft, $fieldRight ) {
1783                 return "($fieldLeft & $fieldRight)";
1784         }
1785
1786         public function bitOr( $fieldLeft, $fieldRight ) {
1787                 return "($fieldLeft | $fieldRight)";
1788         }
1789
1790         public function buildConcat( $stringList ) {
1791                 return 'CONCAT(' . implode( ',', $stringList ) . ')';
1792         }
1793
1794         public function buildGroupConcatField(
1795                 $delim, $table, $field, $conds = '', $join_conds = []
1796         ) {
1797                 $fld = "GROUP_CONCAT($field SEPARATOR " . $this->addQuotes( $delim ) . ')';
1798
1799                 return '(' . $this->selectSQLText( $table, $fld, $conds, null, [], $join_conds ) . ')';
1800         }
1801
1802         public function buildStringCast( $field ) {
1803                 return $field;
1804         }
1805
1806         public function databasesAreIndependent() {
1807                 return false;
1808         }
1809
1810         public function selectDB( $db ) {
1811                 # Stub. Shouldn't cause serious problems if it's not overridden, but
1812                 # if your database engine supports a concept similar to MySQL's
1813                 # databases you may as well.
1814                 $this->mDBname = $db;
1815
1816                 return true;
1817         }
1818
1819         public function getDBname() {
1820                 return $this->mDBname;
1821         }
1822
1823         public function getServer() {
1824                 return $this->mServer;
1825         }
1826
1827         public function tableName( $name, $format = 'quoted' ) {
1828                 # Skip the entire process when we have a string quoted on both ends.
1829                 # Note that we check the end so that we will still quote any use of
1830                 # use of `database`.table. But won't break things if someone wants
1831                 # to query a database table with a dot in the name.
1832                 if ( $this->isQuotedIdentifier( $name ) ) {
1833                         return $name;
1834                 }
1835
1836                 # Lets test for any bits of text that should never show up in a table
1837                 # name. Basically anything like JOIN or ON which are actually part of
1838                 # SQL queries, but may end up inside of the table value to combine
1839                 # sql. Such as how the API is doing.
1840                 # Note that we use a whitespace test rather than a \b test to avoid
1841                 # any remote case where a word like on may be inside of a table name
1842                 # surrounded by symbols which may be considered word breaks.
1843                 if ( preg_match( '/(^|\s)(DISTINCT|JOIN|ON|AS)(\s|$)/i', $name ) !== 0 ) {
1844                         return $name;
1845                 }
1846
1847                 # Split database and table into proper variables.
1848                 list( $database, $schema, $prefix, $table ) = $this->qualifiedTableComponents( $name );
1849
1850                 # Quote $table and apply the prefix if not quoted.
1851                 # $tableName might be empty if this is called from Database::replaceVars()
1852                 $tableName = "{$prefix}{$table}";
1853                 if ( $format === 'quoted'
1854                         && !$this->isQuotedIdentifier( $tableName )
1855                         && $tableName !== ''
1856                 ) {
1857                         $tableName = $this->addIdentifierQuotes( $tableName );
1858                 }
1859
1860                 # Quote $schema and $database and merge them with the table name if needed
1861                 $tableName = $this->prependDatabaseOrSchema( $schema, $tableName, $format );
1862                 $tableName = $this->prependDatabaseOrSchema( $database, $tableName, $format );
1863
1864                 return $tableName;
1865         }
1866
1867         /**
1868          * Get the table components needed for a query given the currently selected database
1869          *
1870          * @param string $name Table name in the form of db.schema.table, db.table, or table
1871          * @return array (DB name or "" for default, schema name, table prefix, table name)
1872          */
1873         protected function qualifiedTableComponents( $name ) {
1874                 # We reverse the explode so that database.table and table both output the correct table.
1875                 $dbDetails = explode( '.', $name, 3 );
1876                 if ( count( $dbDetails ) == 3 ) {
1877                         list( $database, $schema, $table ) = $dbDetails;
1878                         # We don't want any prefix added in this case
1879                         $prefix = '';
1880                 } elseif ( count( $dbDetails ) == 2 ) {
1881                         list( $database, $table ) = $dbDetails;
1882                         # We don't want any prefix added in this case
1883                         $prefix = '';
1884                         # In dbs that support it, $database may actually be the schema
1885                         # but that doesn't affect any of the functionality here
1886                         $schema = '';
1887                 } else {
1888                         list( $table ) = $dbDetails;
1889                         if ( isset( $this->tableAliases[$table] ) ) {
1890                                 $database = $this->tableAliases[$table]['dbname'];
1891                                 $schema = is_string( $this->tableAliases[$table]['schema'] )
1892                                         ? $this->tableAliases[$table]['schema']
1893                                         : $this->mSchema;
1894                                 $prefix = is_string( $this->tableAliases[$table]['prefix'] )
1895                                         ? $this->tableAliases[$table]['prefix']
1896                                         : $this->mTablePrefix;
1897                         } else {
1898                                 $database = '';
1899                                 $schema = $this->mSchema; # Default schema
1900                                 $prefix = $this->mTablePrefix; # Default prefix
1901                         }
1902                 }
1903
1904                 return [ $database, $schema, $prefix, $table ];
1905         }
1906
1907         /**
1908          * @param string|null $namespace Database or schema
1909          * @param string $relation Name of table, view, sequence, etc...
1910          * @param string $format One of (raw, quoted)
1911          * @return string Relation name with quoted and merged $namespace as needed
1912          */
1913         private function prependDatabaseOrSchema( $namespace, $relation, $format ) {
1914                 if ( strlen( $namespace ) ) {
1915                         if ( $format === 'quoted' && !$this->isQuotedIdentifier( $namespace ) ) {
1916                                 $namespace = $this->addIdentifierQuotes( $namespace );
1917                         }
1918                         $relation = $namespace . '.' . $relation;
1919                 }
1920
1921                 return $relation;
1922         }
1923
1924         public function tableNames() {
1925                 $inArray = func_get_args();
1926                 $retVal = [];
1927
1928                 foreach ( $inArray as $name ) {
1929                         $retVal[$name] = $this->tableName( $name );
1930                 }
1931
1932                 return $retVal;
1933         }
1934
1935         public function tableNamesN() {
1936                 $inArray = func_get_args();
1937                 $retVal = [];
1938
1939                 foreach ( $inArray as $name ) {
1940                         $retVal[] = $this->tableName( $name );
1941                 }
1942
1943                 return $retVal;
1944         }
1945
1946         /**
1947          * Get an aliased table name
1948          * e.g. tableName AS newTableName
1949          *
1950          * @param string $name Table name, see tableName()
1951          * @param string|bool $alias Alias (optional)
1952          * @return string SQL name for aliased table. Will not alias a table to its own name
1953          */
1954         protected function tableNameWithAlias( $name, $alias = false ) {
1955                 if ( !$alias || $alias == $name ) {
1956                         return $this->tableName( $name );
1957                 } else {
1958                         return $this->tableName( $name ) . ' ' . $this->addIdentifierQuotes( $alias );
1959                 }
1960         }
1961
1962         /**
1963          * Gets an array of aliased table names
1964          *
1965          * @param array $tables [ [alias] => table ]
1966          * @return string[] See tableNameWithAlias()
1967          */
1968         protected function tableNamesWithAlias( $tables ) {
1969                 $retval = [];
1970                 foreach ( $tables as $alias => $table ) {
1971                         if ( is_numeric( $alias ) ) {
1972                                 $alias = $table;
1973                         }
1974                         $retval[] = $this->tableNameWithAlias( $table, $alias );
1975                 }
1976
1977                 return $retval;
1978         }
1979
1980         /**
1981          * Get an aliased field name
1982          * e.g. fieldName AS newFieldName
1983          *
1984          * @param string $name Field name
1985          * @param string|bool $alias Alias (optional)
1986          * @return string SQL name for aliased field. Will not alias a field to its own name
1987          */
1988         protected function fieldNameWithAlias( $name, $alias = false ) {
1989                 if ( !$alias || (string)$alias === (string)$name ) {
1990                         return $name;
1991                 } else {
1992                         return $name . ' AS ' . $this->addIdentifierQuotes( $alias ); // PostgreSQL needs AS
1993                 }
1994         }
1995
1996         /**
1997          * Gets an array of aliased field names
1998          *
1999          * @param array $fields [ [alias] => field ]
2000          * @return string[] See fieldNameWithAlias()
2001          */
2002         protected function fieldNamesWithAlias( $fields ) {
2003                 $retval = [];
2004                 foreach ( $fields as $alias => $field ) {
2005                         if ( is_numeric( $alias ) ) {
2006                                 $alias = $field;
2007                         }
2008                         $retval[] = $this->fieldNameWithAlias( $field, $alias );
2009                 }
2010
2011                 return $retval;
2012         }
2013
2014         /**
2015          * Get the aliased table name clause for a FROM clause
2016          * which might have a JOIN and/or USE INDEX or IGNORE INDEX clause
2017          *
2018          * @param array $tables ( [alias] => table )
2019          * @param array $use_index Same as for select()
2020          * @param array $ignore_index Same as for select()
2021          * @param array $join_conds Same as for select()
2022          * @return string
2023          */
2024         protected function tableNamesWithIndexClauseOrJOIN(
2025                 $tables, $use_index = [], $ignore_index = [], $join_conds = []
2026         ) {
2027                 $ret = [];
2028                 $retJOIN = [];
2029                 $use_index = (array)$use_index;
2030                 $ignore_index = (array)$ignore_index;
2031                 $join_conds = (array)$join_conds;
2032
2033                 foreach ( $tables as $alias => $table ) {
2034                         if ( !is_string( $alias ) ) {
2035                                 // No alias? Set it equal to the table name
2036                                 $alias = $table;
2037                         }
2038
2039                         if ( is_array( $table ) ) {
2040                                 // A parenthesized group
2041                                 if ( count( $table ) > 1 ) {
2042                                         $joinedTable = '('
2043                                                 . $this->tableNamesWithIndexClauseOrJOIN( $table, $use_index, $ignore_index, $join_conds )
2044                                                 . ')';
2045                                 } else {
2046                                         // Degenerate case
2047                                         $innerTable = reset( $table );
2048                                         $innerAlias = key( $table );
2049                                         $joinedTable = $this->tableNameWithAlias(
2050                                                 $innerTable,
2051                                                 is_string( $innerAlias ) ? $innerAlias : $innerTable
2052                                         );
2053                                 }
2054                         } else {
2055                                 $joinedTable = $this->tableNameWithAlias( $table, $alias );
2056                         }
2057
2058                         // Is there a JOIN clause for this table?
2059                         if ( isset( $join_conds[$alias] ) ) {
2060                                 list( $joinType, $conds ) = $join_conds[$alias];
2061                                 $tableClause = $joinType;
2062                                 $tableClause .= ' ' . $joinedTable;
2063                                 if ( isset( $use_index[$alias] ) ) { // has USE INDEX?
2064                                         $use = $this->useIndexClause( implode( ',', (array)$use_index[$alias] ) );
2065                                         if ( $use != '' ) {
2066                                                 $tableClause .= ' ' . $use;
2067                                         }
2068                                 }
2069                                 if ( isset( $ignore_index[$alias] ) ) { // has IGNORE INDEX?
2070                                         $ignore = $this->ignoreIndexClause(
2071                                                 implode( ',', (array)$ignore_index[$alias] ) );
2072                                         if ( $ignore != '' ) {
2073                                                 $tableClause .= ' ' . $ignore;
2074                                         }
2075                                 }
2076                                 $on = $this->makeList( (array)$conds, self::LIST_AND );
2077                                 if ( $on != '' ) {
2078                                         $tableClause .= ' ON (' . $on . ')';
2079                                 }
2080
2081                                 $retJOIN[] = $tableClause;
2082                         } elseif ( isset( $use_index[$alias] ) ) {
2083                                 // Is there an INDEX clause for this table?
2084                                 $tableClause = $joinedTable;
2085                                 $tableClause .= ' ' . $this->useIndexClause(
2086                                                 implode( ',', (array)$use_index[$alias] )
2087                                         );
2088
2089                                 $ret[] = $tableClause;
2090                         } elseif ( isset( $ignore_index[$alias] ) ) {
2091                                 // Is there an INDEX clause for this table?
2092                                 $tableClause = $joinedTable;
2093                                 $tableClause .= ' ' . $this->ignoreIndexClause(
2094                                                 implode( ',', (array)$ignore_index[$alias] )
2095                                         );
2096
2097                                 $ret[] = $tableClause;
2098                         } else {
2099                                 $tableClause = $joinedTable;
2100
2101                                 $ret[] = $tableClause;
2102                         }
2103                 }
2104
2105                 // We can't separate explicit JOIN clauses with ',', use ' ' for those
2106                 $implicitJoins = !empty( $ret ) ? implode( ',', $ret ) : "";
2107                 $explicitJoins = !empty( $retJOIN ) ? implode( ' ', $retJOIN ) : "";
2108
2109                 // Compile our final table clause
2110                 return implode( ' ', [ $implicitJoins, $explicitJoins ] );
2111         }
2112
2113         /**
2114          * Allows for index remapping in queries where this is not consistent across DBMS
2115          *
2116          * @param string $index
2117          * @return string
2118          */
2119         protected function indexName( $index ) {
2120                 return $index;
2121         }
2122
2123         public function addQuotes( $s ) {
2124                 if ( $s instanceof Blob ) {
2125                         $s = $s->fetch();
2126                 }
2127                 if ( $s === null ) {
2128                         return 'NULL';
2129                 } elseif ( is_bool( $s ) ) {
2130                         return (int)$s;
2131                 } else {
2132                         # This will also quote numeric values. This should be harmless,
2133                         # and protects against weird problems that occur when they really
2134                         # _are_ strings such as article titles and string->number->string
2135                         # conversion is not 1:1.
2136                         return "'" . $this->strencode( $s ) . "'";
2137                 }
2138         }
2139
2140         /**
2141          * Quotes an identifier using `backticks` or "double quotes" depending on the database type.
2142          * MySQL uses `backticks` while basically everything else uses double quotes.
2143          * Since MySQL is the odd one out here the double quotes are our generic
2144          * and we implement backticks in DatabaseMysqlBase.
2145          *
2146          * @param string $s
2147          * @return string
2148          */
2149         public function addIdentifierQuotes( $s ) {
2150                 return '"' . str_replace( '"', '""', $s ) . '"';
2151         }
2152
2153         /**
2154          * Returns if the given identifier looks quoted or not according to
2155          * the database convention for quoting identifiers .
2156          *
2157          * @note Do not use this to determine if untrusted input is safe.
2158          *   A malicious user can trick this function.
2159          * @param string $name
2160          * @return bool
2161          */
2162         public function isQuotedIdentifier( $name ) {
2163                 return $name[0] == '"' && substr( $name, -1, 1 ) == '"';
2164         }
2165
2166         /**
2167          * @param string $s
2168          * @param string $escapeChar
2169          * @return string
2170          */
2171         protected function escapeLikeInternal( $s, $escapeChar = '`' ) {
2172                 return str_replace( [ $escapeChar, '%', '_' ],
2173                         [ "{$escapeChar}{$escapeChar}", "{$escapeChar}%", "{$escapeChar}_" ],
2174                         $s );
2175         }
2176
2177         public function buildLike() {
2178                 $params = func_get_args();
2179
2180                 if ( count( $params ) > 0 && is_array( $params[0] ) ) {
2181                         $params = $params[0];
2182                 }
2183
2184                 $s = '';
2185
2186                 // We use ` instead of \ as the default LIKE escape character, since addQuotes()
2187                 // may escape backslashes, creating problems of double escaping. The `
2188                 // character has good cross-DBMS compatibility, avoiding special operators
2189                 // in MS SQL like ^ and %
2190                 $escapeChar = '`';
2191
2192                 foreach ( $params as $value ) {
2193                         if ( $value instanceof LikeMatch ) {
2194                                 $s .= $value->toString();
2195                         } else {
2196                                 $s .= $this->escapeLikeInternal( $value, $escapeChar );
2197                         }
2198                 }
2199
2200                 return ' LIKE ' . $this->addQuotes( $s ) . ' ESCAPE ' . $this->addQuotes( $escapeChar ) . ' ';
2201         }
2202
2203         public function anyChar() {
2204                 return new LikeMatch( '_' );
2205         }
2206
2207         public function anyString() {
2208                 return new LikeMatch( '%' );
2209         }
2210
2211         public function nextSequenceValue( $seqName ) {
2212                 return null;
2213         }
2214
2215         /**
2216          * USE INDEX clause. Unlikely to be useful for anything but MySQL. This
2217          * is only needed because a) MySQL must be as efficient as possible due to
2218          * its use on Wikipedia, and b) MySQL 4.0 is kind of dumb sometimes about
2219          * which index to pick. Anyway, other databases might have different
2220          * indexes on a given table. So don't bother overriding this unless you're
2221          * MySQL.
2222          * @param string $index
2223          * @return string
2224          */
2225         public function useIndexClause( $index ) {
2226                 return '';
2227         }
2228
2229         /**
2230          * IGNORE INDEX clause. Unlikely to be useful for anything but MySQL. This
2231          * is only needed because a) MySQL must be as efficient as possible due to
2232          * its use on Wikipedia, and b) MySQL 4.0 is kind of dumb sometimes about
2233          * which index to pick. Anyway, other databases might have different
2234          * indexes on a given table. So don't bother overriding this unless you're
2235          * MySQL.
2236          * @param string $index
2237          * @return string
2238          */
2239         public function ignoreIndexClause( $index ) {
2240                 return '';
2241         }
2242
2243         public function replace( $table, $uniqueIndexes, $rows, $fname = __METHOD__ ) {
2244                 $quotedTable = $this->tableName( $table );
2245
2246                 if ( count( $rows ) == 0 ) {
2247                         return;
2248                 }
2249
2250                 # Single row case
2251                 if ( !is_array( reset( $rows ) ) ) {
2252                         $rows = [ $rows ];
2253                 }
2254
2255                 // @FXIME: this is not atomic, but a trx would break affectedRows()
2256                 foreach ( $rows as $row ) {
2257                         # Delete rows which collide
2258                         if ( $uniqueIndexes ) {
2259                                 $sql = "DELETE FROM $quotedTable WHERE ";
2260                                 $first = true;
2261                                 foreach ( $uniqueIndexes as $index ) {
2262                                         if ( $first ) {
2263                                                 $first = false;
2264                                                 $sql .= '( ';
2265                                         } else {
2266                                                 $sql .= ' ) OR ( ';
2267                                         }
2268                                         if ( is_array( $index ) ) {
2269                                                 $first2 = true;
2270                                                 foreach ( $index as $col ) {
2271                                                         if ( $first2 ) {
2272                                                                 $first2 = false;
2273                                                         } else {
2274                                                                 $sql .= ' AND ';
2275                                                         }
2276                                                         $sql .= $col . '=' . $this->addQuotes( $row[$col] );
2277                                                 }
2278                                         } else {
2279                                                 $sql .= $index . '=' . $this->addQuotes( $row[$index] );
2280                                         }
2281                                 }
2282                                 $sql .= ' )';
2283                                 $this->query( $sql, $fname );
2284                         }
2285
2286                         # Now insert the row
2287                         $this->insert( $table, $row, $fname );
2288                 }
2289         }
2290
2291         /**
2292          * REPLACE query wrapper for MySQL and SQLite, which have a native REPLACE
2293          * statement.
2294          *
2295          * @param string $table Table name
2296          * @param array|string $rows Row(s) to insert
2297          * @param string $fname Caller function name
2298          *
2299          * @return ResultWrapper
2300          */
2301         protected function nativeReplace( $table, $rows, $fname ) {
2302                 $table = $this->tableName( $table );
2303
2304                 # Single row case
2305                 if ( !is_array( reset( $rows ) ) ) {
2306                         $rows = [ $rows ];
2307                 }
2308
2309                 $sql = "REPLACE INTO $table (" . implode( ',', array_keys( $rows[0] ) ) . ') VALUES ';
2310                 $first = true;
2311
2312                 foreach ( $rows as $row ) {
2313                         if ( $first ) {
2314                                 $first = false;
2315                         } else {
2316                                 $sql .= ',';
2317                         }
2318
2319                         $sql .= '(' . $this->makeList( $row ) . ')';
2320                 }
2321
2322                 return $this->query( $sql, $fname );
2323         }
2324
2325         public function upsert( $table, array $rows, array $uniqueIndexes, array $set,
2326                 $fname = __METHOD__
2327         ) {
2328                 if ( !count( $rows ) ) {
2329                         return true; // nothing to do
2330                 }
2331
2332                 if ( !is_array( reset( $rows ) ) ) {
2333                         $rows = [ $rows ];
2334                 }
2335
2336                 if ( count( $uniqueIndexes ) ) {
2337                         $clauses = []; // list WHERE clauses that each identify a single row
2338                         foreach ( $rows as $row ) {
2339                                 foreach ( $uniqueIndexes as $index ) {
2340                                         $index = is_array( $index ) ? $index : [ $index ]; // columns
2341                                         $rowKey = []; // unique key to this row
2342                                         foreach ( $index as $column ) {
2343                                                 $rowKey[$column] = $row[$column];
2344                                         }
2345                                         $clauses[] = $this->makeList( $rowKey, self::LIST_AND );
2346                                 }
2347                         }
2348                         $where = [ $this->makeList( $clauses, self::LIST_OR ) ];
2349                 } else {
2350                         $where = false;
2351                 }
2352
2353                 $useTrx = !$this->mTrxLevel;
2354                 if ( $useTrx ) {
2355                         $this->begin( $fname, self::TRANSACTION_INTERNAL );
2356                 }
2357                 try {
2358                         # Update any existing conflicting row(s)
2359                         if ( $where !== false ) {
2360                                 $ok = $this->update( $table, $set, $where, $fname );
2361                         } else {
2362                                 $ok = true;
2363                         }
2364                         # Now insert any non-conflicting row(s)
2365                         $ok = $this->insert( $table, $rows, $fname, [ 'IGNORE' ] ) && $ok;
2366                 } catch ( Exception $e ) {
2367                         if ( $useTrx ) {
2368                                 $this->rollback( $fname, self::FLUSHING_INTERNAL );
2369                         }
2370                         throw $e;
2371                 }
2372                 if ( $useTrx ) {
2373                         $this->commit( $fname, self::FLUSHING_INTERNAL );
2374                 }
2375
2376                 return $ok;
2377         }
2378
2379         public function deleteJoin( $delTable, $joinTable, $delVar, $joinVar, $conds,
2380                 $fname = __METHOD__
2381         ) {
2382                 if ( !$conds ) {
2383                         throw new DBUnexpectedError( $this, __METHOD__ . ' called with empty $conds' );
2384                 }
2385
2386                 $delTable = $this->tableName( $delTable );
2387                 $joinTable = $this->tableName( $joinTable );
2388                 $sql = "DELETE FROM $delTable WHERE $delVar IN (SELECT $joinVar FROM $joinTable ";
2389                 if ( $conds != '*' ) {
2390                         $sql .= 'WHERE ' . $this->makeList( $conds, self::LIST_AND );
2391                 }
2392                 $sql .= ')';
2393
2394                 $this->query( $sql, $fname );
2395         }
2396
2397         public function textFieldSize( $table, $field ) {
2398                 $table = $this->tableName( $table );
2399                 $sql = "SHOW COLUMNS FROM $table LIKE \"$field\";";
2400                 $res = $this->query( $sql, __METHOD__ );
2401                 $row = $this->fetchObject( $res );
2402
2403                 $m = [];
2404
2405                 if ( preg_match( '/\((.*)\)/', $row->Type, $m ) ) {
2406                         $size = $m[1];
2407                 } else {
2408                         $size = -1;
2409                 }
2410
2411                 return $size;
2412         }
2413
2414         public function delete( $table, $conds, $fname = __METHOD__ ) {
2415                 if ( !$conds ) {
2416                         throw new DBUnexpectedError( $this, __METHOD__ . ' called with no conditions' );
2417                 }
2418
2419                 $table = $this->tableName( $table );
2420                 $sql = "DELETE FROM $table";
2421
2422                 if ( $conds != '*' ) {
2423                         if ( is_array( $conds ) ) {
2424                                 $conds = $this->makeList( $conds, self::LIST_AND );
2425                         }
2426                         $sql .= ' WHERE ' . $conds;
2427                 }
2428
2429                 return $this->query( $sql, $fname );
2430         }
2431
2432         public function insertSelect(
2433                 $destTable, $srcTable, $varMap, $conds,
2434                 $fname = __METHOD__, $insertOptions = [], $selectOptions = [], $selectJoinConds = []
2435         ) {
2436                 if ( $this->cliMode ) {
2437                         // For massive migrations with downtime, we don't want to select everything
2438                         // into memory and OOM, so do all this native on the server side if possible.
2439                         return $this->nativeInsertSelect(
2440                                 $destTable,
2441                                 $srcTable,
2442                                 $varMap,
2443                                 $conds,
2444                                 $fname,
2445                                 $insertOptions,
2446                                 $selectOptions,
2447                                 $selectJoinConds
2448                         );
2449                 }
2450
2451                 return $this->nonNativeInsertSelect(
2452                         $destTable,
2453                         $srcTable,
2454                         $varMap,
2455                         $conds,
2456                         $fname,
2457                         $insertOptions,
2458                         $selectOptions,
2459                         $selectJoinConds
2460                 );
2461         }
2462
2463         /**
2464          * Implementation of insertSelect() based on select() and insert()
2465          *
2466          * @see IDatabase::insertSelect()
2467          * @since 1.30
2468          * @param string $destTable
2469          * @param string|array $srcTable
2470          * @param array $varMap
2471          * @param array $conds
2472          * @param string $fname
2473          * @param array $insertOptions
2474          * @param array $selectOptions
2475          * @param array $selectJoinConds
2476          * @return bool
2477          */
2478         protected function nonNativeInsertSelect( $destTable, $srcTable, $varMap, $conds,
2479                 $fname = __METHOD__,
2480                 $insertOptions = [], $selectOptions = [], $selectJoinConds = []
2481         ) {
2482                 // For web requests, do a locking SELECT and then INSERT. This puts the SELECT burden
2483                 // on only the master (without needing row-based-replication). It also makes it easy to
2484                 // know how big the INSERT is going to be.
2485                 $fields = [];
2486                 foreach ( $varMap as $dstColumn => $sourceColumnOrSql ) {
2487                         $fields[] = $this->fieldNameWithAlias( $sourceColumnOrSql, $dstColumn );
2488                 }
2489                 $selectOptions[] = 'FOR UPDATE';
2490                 $res = $this->select(
2491                         $srcTable, implode( ',', $fields ), $conds, $fname, $selectOptions, $selectJoinConds
2492                 );
2493                 if ( !$res ) {
2494                         return false;
2495                 }
2496
2497                 $rows = [];
2498                 foreach ( $res as $row ) {
2499                         $rows[] = (array)$row;
2500                 }
2501
2502                 return $this->insert( $destTable, $rows, $fname, $insertOptions );
2503         }
2504
2505         /**
2506          * Native server-side implementation of insertSelect() for situations where
2507          * we don't want to select everything into memory
2508          *
2509          * @see IDatabase::insertSelect()
2510          * @param string $destTable
2511          * @param string|array $srcTable
2512          * @param array $varMap
2513          * @param array $conds
2514          * @param string $fname
2515          * @param array $insertOptions
2516          * @param array $selectOptions
2517          * @param array $selectJoinConds
2518          * @return bool
2519          */
2520         protected function nativeInsertSelect( $destTable, $srcTable, $varMap, $conds,
2521                 $fname = __METHOD__,
2522                 $insertOptions = [], $selectOptions = [], $selectJoinConds = []
2523         ) {
2524                 $destTable = $this->tableName( $destTable );
2525
2526                 if ( !is_array( $insertOptions ) ) {
2527                         $insertOptions = [ $insertOptions ];
2528                 }
2529
2530                 $insertOptions = $this->makeInsertOptions( $insertOptions );
2531
2532                 $selectSql = $this->selectSQLText(
2533                         $srcTable,
2534                         array_values( $varMap ),
2535                         $conds,
2536                         $fname,
2537                         $selectOptions,
2538                         $selectJoinConds
2539                 );
2540
2541                 $sql = "INSERT $insertOptions" .
2542                         " INTO $destTable (" . implode( ',', array_keys( $varMap ) ) . ') ' .
2543                         $selectSql;
2544
2545                 return $this->query( $sql, $fname );
2546         }
2547
2548         /**
2549          * Construct a LIMIT query with optional offset. This is used for query
2550          * pages. The SQL should be adjusted so that only the first $limit rows
2551          * are returned. If $offset is provided as well, then the first $offset
2552          * rows should be discarded, and the next $limit rows should be returned.
2553          * If the result of the query is not ordered, then the rows to be returned
2554          * are theoretically arbitrary.
2555          *
2556          * $sql is expected to be a SELECT, if that makes a difference.
2557          *
2558          * The version provided by default works in MySQL and SQLite. It will very
2559          * likely need to be overridden for most other DBMSes.
2560          *
2561          * @param string $sql SQL query we will append the limit too
2562          * @param int $limit The SQL limit
2563          * @param int|bool $offset The SQL offset (default false)
2564          * @throws DBUnexpectedError
2565          * @return string
2566          */
2567         public function limitResult( $sql, $limit, $offset = false ) {
2568                 if ( !is_numeric( $limit ) ) {
2569                         throw new DBUnexpectedError( $this,
2570                                 "Invalid non-numeric limit passed to limitResult()\n" );
2571                 }
2572
2573                 return "$sql LIMIT "
2574                 . ( ( is_numeric( $offset ) && $offset != 0 ) ? "{$offset}," : "" )
2575                 . "{$limit} ";
2576         }
2577
2578         public function unionSupportsOrderAndLimit() {
2579                 return true; // True for almost every DB supported
2580         }
2581
2582         public function unionQueries( $sqls, $all ) {
2583                 $glue = $all ? ') UNION ALL (' : ') UNION (';
2584
2585                 return '(' . implode( $glue, $sqls ) . ')';
2586         }
2587
2588         public function unionConditionPermutations(
2589                 $table, $vars, array $permute_conds, $extra_conds = '', $fname = __METHOD__,
2590                 $options = [], $join_conds = []
2591         ) {
2592                 // First, build the Cartesian product of $permute_conds
2593                 $conds = [ [] ];
2594                 foreach ( $permute_conds as $field => $values ) {
2595                         if ( !$values ) {
2596                                 // Skip empty $values
2597                                 continue;
2598                         }
2599                         $values = array_unique( $values ); // For sanity
2600                         $newConds = [];
2601                         foreach ( $conds as $cond ) {
2602                                 foreach ( $values as $value ) {
2603                                         $cond[$field] = $value;
2604                                         $newConds[] = $cond; // Arrays are by-value, not by-reference, so this works
2605                                 }
2606                         }
2607                         $conds = $newConds;
2608                 }
2609
2610                 $extra_conds = $extra_conds === '' ? [] : (array)$extra_conds;
2611
2612                 // If there's just one condition and no subordering, hand off to
2613                 // selectSQLText directly.
2614                 if ( count( $conds ) === 1 &&
2615                         ( !isset( $options['INNER ORDER BY'] ) || !$this->unionSupportsOrderAndLimit() )
2616                 ) {
2617                         return $this->selectSQLText(
2618                                 $table, $vars, $conds[0] + $extra_conds, $fname, $options, $join_conds
2619                         );
2620                 }
2621
2622                 // Otherwise, we need to pull out the order and limit to apply after
2623                 // the union. Then build the SQL queries for each set of conditions in
2624                 // $conds. Then union them together (using UNION ALL, because the
2625                 // product *should* already be distinct).
2626                 $orderBy = $this->makeOrderBy( $options );
2627                 $limit = isset( $options['LIMIT'] ) ? $options['LIMIT'] : null;
2628                 $offset = isset( $options['OFFSET'] ) ? $options['OFFSET'] : false;
2629                 $all = empty( $options['NOTALL'] ) && !in_array( 'NOTALL', $options );
2630                 if ( !$this->unionSupportsOrderAndLimit() ) {
2631                         unset( $options['ORDER BY'], $options['LIMIT'], $options['OFFSET'] );
2632                 } else {
2633                         if ( array_key_exists( 'INNER ORDER BY', $options ) ) {
2634                                 $options['ORDER BY'] = $options['INNER ORDER BY'];
2635                         }
2636                         if ( $limit !== null && is_numeric( $offset ) && $offset != 0 ) {
2637                                 // We need to increase the limit by the offset rather than
2638                                 // using the offset directly, otherwise it'll skip incorrectly
2639                                 // in the subqueries.
2640                                 $options['LIMIT'] = $limit + $offset;
2641                                 unset( $options['OFFSET'] );
2642                         }
2643                 }
2644
2645                 $sqls = [];
2646                 foreach ( $conds as $cond ) {
2647                         $sqls[] = $this->selectSQLText(
2648                                 $table, $vars, $cond + $extra_conds, $fname, $options, $join_conds
2649                         );
2650                 }
2651                 $sql = $this->unionQueries( $sqls, $all ) . $orderBy;
2652                 if ( $limit !== null ) {
2653                         $sql = $this->limitResult( $sql, $limit, $offset );
2654                 }
2655
2656                 return $sql;
2657         }
2658
2659         public function conditional( $cond, $trueVal, $falseVal ) {
2660                 if ( is_array( $cond ) ) {
2661                         $cond = $this->makeList( $cond, self::LIST_AND );
2662                 }
2663
2664                 return " (CASE WHEN $cond THEN $trueVal ELSE $falseVal END) ";
2665         }
2666
2667         public function strreplace( $orig, $old, $new ) {
2668                 return "REPLACE({$orig}, {$old}, {$new})";
2669         }
2670
2671         public function getServerUptime() {
2672                 return 0;
2673         }
2674
2675         public function wasDeadlock() {
2676                 return false;
2677         }
2678
2679         public function wasLockTimeout() {
2680                 return false;
2681         }
2682
2683         public function wasErrorReissuable() {
2684                 return false;
2685         }
2686
2687         public function wasReadOnlyError() {
2688                 return false;
2689         }
2690
2691         /**
2692          * Do not use this method outside of Database/DBError classes
2693          *
2694          * @param int|string $errno
2695          * @return bool Whether the given query error was a connection drop
2696          */
2697         public function wasConnectionError( $errno ) {
2698                 return false;
2699         }
2700
2701         public function deadlockLoop() {
2702                 $args = func_get_args();
2703                 $function = array_shift( $args );
2704                 $tries = self::DEADLOCK_TRIES;
2705
2706                 $this->begin( __METHOD__ );
2707
2708                 $retVal = null;
2709                 /** @var Exception $e */
2710                 $e = null;
2711                 do {
2712                         try {
2713                                 $retVal = call_user_func_array( $function, $args );
2714                                 break;
2715                         } catch ( DBQueryError $e ) {
2716                                 if ( $this->wasDeadlock() ) {
2717                                         // Retry after a randomized delay
2718                                         usleep( mt_rand( self::DEADLOCK_DELAY_MIN, self::DEADLOCK_DELAY_MAX ) );
2719                                 } else {
2720                                         // Throw the error back up
2721                                         throw $e;
2722                                 }
2723                         }
2724                 } while ( --$tries > 0 );
2725
2726                 if ( $tries <= 0 ) {
2727                         // Too many deadlocks; give up
2728                         $this->rollback( __METHOD__ );
2729                         throw $e;
2730                 } else {
2731                         $this->commit( __METHOD__ );
2732
2733                         return $retVal;
2734                 }
2735         }
2736
2737         public function masterPosWait( DBMasterPos $pos, $timeout ) {
2738                 # Real waits are implemented in the subclass.
2739                 return 0;
2740         }
2741
2742         public function getReplicaPos() {
2743                 # Stub
2744                 return false;
2745         }
2746
2747         public function getMasterPos() {
2748                 # Stub
2749                 return false;
2750         }
2751
2752         public function serverIsReadOnly() {
2753                 return false;
2754         }
2755
2756         final public function onTransactionResolution( callable $callback, $fname = __METHOD__ ) {
2757                 if ( !$this->mTrxLevel ) {
2758                         throw new DBUnexpectedError( $this, "No transaction is active." );
2759                 }
2760                 $this->mTrxEndCallbacks[] = [ $callback, $fname ];
2761         }
2762
2763         final public function onTransactionIdle( callable $callback, $fname = __METHOD__ ) {
2764                 $this->mTrxIdleCallbacks[] = [ $callback, $fname ];
2765                 if ( !$this->mTrxLevel ) {
2766                         $this->runOnTransactionIdleCallbacks( self::TRIGGER_IDLE );
2767                 }
2768         }
2769
2770         final public function onTransactionPreCommitOrIdle( callable $callback, $fname = __METHOD__ ) {
2771                 if ( $this->mTrxLevel || $this->getFlag( self::DBO_TRX ) ) {
2772                         // As long as DBO_TRX is set, writes will accumulate until the load balancer issues
2773                         // an implicit commit of all peer databases. This is true even if a transaction has
2774                         // not yet been triggered by writes; make sure $callback runs *after* any such writes.
2775                         $this->mTrxPreCommitCallbacks[] = [ $callback, $fname ];
2776                 } else {
2777                         // No transaction is active nor will start implicitly, so make one for this callback
2778                         $this->startAtomic( __METHOD__ );
2779                         try {
2780                                 call_user_func( $callback );
2781                                 $this->endAtomic( __METHOD__ );
2782                         } catch ( Exception $e ) {
2783                                 $this->rollback( __METHOD__, self::FLUSHING_INTERNAL );
2784                                 throw $e;
2785                         }
2786                 }
2787         }
2788
2789         final public function setTransactionListener( $name, callable $callback = null ) {
2790                 if ( $callback ) {
2791                         $this->mTrxRecurringCallbacks[$name] = $callback;
2792                 } else {
2793                         unset( $this->mTrxRecurringCallbacks[$name] );
2794                 }
2795         }
2796
2797         /**
2798          * Whether to disable running of post-COMMIT/ROLLBACK callbacks
2799          *
2800          * This method should not be used outside of Database/LoadBalancer
2801          *
2802          * @param bool $suppress
2803          * @since 1.28
2804          */
2805         final public function setTrxEndCallbackSuppression( $suppress ) {
2806                 $this->mTrxEndCallbacksSuppressed = $suppress;
2807         }
2808
2809         /**
2810          * Actually run and consume any "on transaction idle/resolution" callbacks.
2811          *
2812          * This method should not be used outside of Database/LoadBalancer
2813          *
2814          * @param int $trigger IDatabase::TRIGGER_* constant
2815          * @since 1.20
2816          * @throws Exception
2817          */
2818         public function runOnTransactionIdleCallbacks( $trigger ) {
2819                 if ( $this->mTrxEndCallbacksSuppressed ) {
2820                         return;
2821                 }
2822
2823                 $autoTrx = $this->getFlag( self::DBO_TRX ); // automatic begin() enabled?
2824                 /** @var Exception $e */
2825                 $e = null; // first exception
2826                 do { // callbacks may add callbacks :)
2827                         $callbacks = array_merge(
2828                                 $this->mTrxIdleCallbacks,
2829                                 $this->mTrxEndCallbacks // include "transaction resolution" callbacks
2830                         );
2831                         $this->mTrxIdleCallbacks = []; // consumed (and recursion guard)
2832                         $this->mTrxEndCallbacks = []; // consumed (recursion guard)
2833                         foreach ( $callbacks as $callback ) {
2834                                 try {
2835                                         list( $phpCallback ) = $callback;
2836                                         $this->clearFlag( self::DBO_TRX ); // make each query its own transaction
2837                                         call_user_func_array( $phpCallback, [ $trigger ] );
2838                                         if ( $autoTrx ) {
2839                                                 $this->setFlag( self::DBO_TRX ); // restore automatic begin()
2840                                         } else {
2841                                                 $this->clearFlag( self::DBO_TRX ); // restore auto-commit
2842                                         }
2843                                 } catch ( Exception $ex ) {
2844                                         call_user_func( $this->errorLogger, $ex );
2845                                         $e = $e ?: $ex;
2846                                         // Some callbacks may use startAtomic/endAtomic, so make sure
2847                                         // their transactions are ended so other callbacks don't fail
2848                                         if ( $this->trxLevel() ) {
2849                                                 $this->rollback( __METHOD__, self::FLUSHING_INTERNAL );
2850                                         }
2851                                 }
2852                         }
2853                 } while ( count( $this->mTrxIdleCallbacks ) );
2854
2855                 if ( $e instanceof Exception ) {
2856                         throw $e; // re-throw any first exception
2857                 }
2858         }
2859
2860         /**
2861          * Actually run and consume any "on transaction pre-commit" callbacks.
2862          *
2863          * This method should not be used outside of Database/LoadBalancer
2864          *
2865          * @since 1.22
2866          * @throws Exception
2867          */
2868         public function runOnTransactionPreCommitCallbacks() {
2869                 $e = null; // first exception
2870                 do { // callbacks may add callbacks :)
2871                         $callbacks = $this->mTrxPreCommitCallbacks;
2872                         $this->mTrxPreCommitCallbacks = []; // consumed (and recursion guard)
2873                         foreach ( $callbacks as $callback ) {
2874                                 try {
2875                                         list( $phpCallback ) = $callback;
2876                                         call_user_func( $phpCallback );
2877                                 } catch ( Exception $ex ) {
2878                                         call_user_func( $this->errorLogger, $ex );
2879                                         $e = $e ?: $ex;
2880                                 }
2881                         }
2882                 } while ( count( $this->mTrxPreCommitCallbacks ) );
2883
2884                 if ( $e instanceof Exception ) {
2885                         throw $e; // re-throw any first exception
2886                 }
2887         }
2888
2889         /**
2890          * Actually run any "transaction listener" callbacks.
2891          *
2892          * This method should not be used outside of Database/LoadBalancer
2893          *
2894          * @param int $trigger IDatabase::TRIGGER_* constant
2895          * @throws Exception
2896          * @since 1.20
2897          */
2898         public function runTransactionListenerCallbacks( $trigger ) {
2899                 if ( $this->mTrxEndCallbacksSuppressed ) {
2900                         return;
2901                 }
2902
2903                 /** @var Exception $e */
2904                 $e = null; // first exception
2905
2906                 foreach ( $this->mTrxRecurringCallbacks as $phpCallback ) {
2907                         try {
2908                                 $phpCallback( $trigger, $this );
2909                         } catch ( Exception $ex ) {
2910                                 call_user_func( $this->errorLogger, $ex );
2911                                 $e = $e ?: $ex;
2912                         }
2913                 }
2914
2915                 if ( $e instanceof Exception ) {
2916                         throw $e; // re-throw any first exception
2917                 }
2918         }
2919
2920         final public function startAtomic( $fname = __METHOD__ ) {
2921                 if ( !$this->mTrxLevel ) {
2922                         $this->begin( $fname, self::TRANSACTION_INTERNAL );
2923                         // If DBO_TRX is set, a series of startAtomic/endAtomic pairs will result
2924                         // in all changes being in one transaction to keep requests transactional.
2925                         if ( !$this->getFlag( self::DBO_TRX ) ) {
2926                                 $this->mTrxAutomaticAtomic = true;
2927                         }
2928                 }
2929
2930                 $this->mTrxAtomicLevels[] = $fname;
2931         }
2932
2933         final public function endAtomic( $fname = __METHOD__ ) {
2934                 if ( !$this->mTrxLevel ) {
2935                         throw new DBUnexpectedError( $this, "No atomic transaction is open (got $fname)." );
2936                 }
2937                 if ( !$this->mTrxAtomicLevels ||
2938                         array_pop( $this->mTrxAtomicLevels ) !== $fname
2939                 ) {
2940                         throw new DBUnexpectedError( $this, "Invalid atomic section ended (got $fname)." );
2941                 }
2942
2943                 if ( !$this->mTrxAtomicLevels && $this->mTrxAutomaticAtomic ) {
2944                         $this->commit( $fname, self::FLUSHING_INTERNAL );
2945                 }
2946         }
2947
2948         final public function doAtomicSection( $fname, callable $callback ) {
2949                 $this->startAtomic( $fname );
2950                 try {
2951                         $res = call_user_func_array( $callback, [ $this, $fname ] );
2952                 } catch ( Exception $e ) {
2953                         $this->rollback( $fname, self::FLUSHING_INTERNAL );
2954                         throw $e;
2955                 }
2956                 $this->endAtomic( $fname );
2957
2958                 return $res;
2959         }
2960
2961         final public function begin( $fname = __METHOD__, $mode = self::TRANSACTION_EXPLICIT ) {
2962                 // Protect against mismatched atomic section, transaction nesting, and snapshot loss
2963                 if ( $this->mTrxLevel ) {
2964                         if ( $this->mTrxAtomicLevels ) {
2965                                 $levels = implode( ', ', $this->mTrxAtomicLevels );
2966                                 $msg = "$fname: Got explicit BEGIN while atomic section(s) $levels are open.";
2967                                 throw new DBUnexpectedError( $this, $msg );
2968                         } elseif ( !$this->mTrxAutomatic ) {
2969                                 $msg = "$fname: Explicit transaction already active (from {$this->mTrxFname}).";
2970                                 throw new DBUnexpectedError( $this, $msg );
2971                         } else {
2972                                 // @TODO: make this an exception at some point
2973                                 $msg = "$fname: Implicit transaction already active (from {$this->mTrxFname}).";
2974                                 $this->queryLogger->error( $msg );
2975                                 return; // join the main transaction set
2976                         }
2977                 } elseif ( $this->getFlag( self::DBO_TRX ) && $mode !== self::TRANSACTION_INTERNAL ) {
2978                         // @TODO: make this an exception at some point
2979                         $msg = "$fname: Implicit transaction expected (DBO_TRX set).";
2980                         $this->queryLogger->error( $msg );
2981                         return; // let any writes be in the main transaction
2982                 }
2983
2984                 // Avoid fatals if close() was called
2985                 $this->assertOpen();
2986
2987                 $this->doBegin( $fname );
2988                 $this->mTrxTimestamp = microtime( true );
2989                 $this->mTrxFname = $fname;
2990                 $this->mTrxDoneWrites = false;
2991                 $this->mTrxAutomaticAtomic = false;
2992                 $this->mTrxAtomicLevels = [];
2993                 $this->mTrxShortId = sprintf( '%06x', mt_rand( 0, 0xffffff ) );
2994                 $this->mTrxWriteDuration = 0.0;
2995                 $this->mTrxWriteQueryCount = 0;
2996                 $this->mTrxWriteAffectedRows = 0;
2997                 $this->mTrxWriteAdjDuration = 0.0;
2998                 $this->mTrxWriteAdjQueryCount = 0;
2999                 $this->mTrxWriteCallers = [];
3000                 // First SELECT after BEGIN will establish the snapshot in REPEATABLE-READ.
3001                 // Get an estimate of the replica DB lag before then, treating estimate staleness
3002                 // as lag itself just to be safe
3003                 $status = $this->getApproximateLagStatus();
3004                 $this->mTrxReplicaLag = $status['lag'] + ( microtime( true ) - $status['since'] );
3005                 // T147697: make explicitTrxActive() return true until begin() finishes. This way, no
3006                 // caller will think its OK to muck around with the transaction just because startAtomic()
3007                 // has not yet completed (e.g. setting mTrxAtomicLevels).
3008                 $this->mTrxAutomatic = ( $mode === self::TRANSACTION_INTERNAL );
3009         }
3010
3011         /**
3012          * Issues the BEGIN command to the database server.
3013          *
3014          * @see Database::begin()
3015          * @param string $fname
3016          */
3017         protected function doBegin( $fname ) {
3018                 $this->query( 'BEGIN', $fname );
3019                 $this->mTrxLevel = 1;
3020         }
3021
3022         final public function commit( $fname = __METHOD__, $flush = '' ) {
3023                 if ( $this->mTrxLevel && $this->mTrxAtomicLevels ) {
3024                         // There are still atomic sections open. This cannot be ignored
3025                         $levels = implode( ', ', $this->mTrxAtomicLevels );
3026                         throw new DBUnexpectedError(
3027                                 $this,
3028                                 "$fname: Got COMMIT while atomic sections $levels are still open."
3029                         );
3030                 }
3031
3032                 if ( $flush === self::FLUSHING_INTERNAL || $flush === self::FLUSHING_ALL_PEERS ) {
3033                         if ( !$this->mTrxLevel ) {
3034                                 return; // nothing to do
3035                         } elseif ( !$this->mTrxAutomatic ) {
3036                                 throw new DBUnexpectedError(
3037                                         $this,
3038                                         "$fname: Flushing an explicit transaction, getting out of sync."
3039                                 );
3040                         }
3041                 } else {
3042                         if ( !$this->mTrxLevel ) {
3043                                 $this->queryLogger->error(
3044                                         "$fname: No transaction to commit, something got out of sync." );
3045                                 return; // nothing to do
3046                         } elseif ( $this->mTrxAutomatic ) {
3047                                 // @TODO: make this an exception at some point
3048                                 $msg = "$fname: Explicit commit of implicit transaction.";
3049                                 $this->queryLogger->error( $msg );
3050                                 return; // wait for the main transaction set commit round
3051                         }
3052                 }
3053
3054                 // Avoid fatals if close() was called
3055                 $this->assertOpen();
3056
3057                 $this->runOnTransactionPreCommitCallbacks();
3058                 $writeTime = $this->pendingWriteQueryDuration( self::ESTIMATE_DB_APPLY );
3059                 $this->doCommit( $fname );
3060                 if ( $this->mTrxDoneWrites ) {
3061                         $this->mLastWriteTime = microtime( true );
3062                         $this->trxProfiler->transactionWritingOut(
3063                                 $this->mServer,
3064                                 $this->mDBname,
3065                                 $this->mTrxShortId,
3066                                 $writeTime,
3067                                 $this->mTrxWriteAffectedRows
3068                         );
3069                 }
3070
3071                 $this->runOnTransactionIdleCallbacks( self::TRIGGER_COMMIT );
3072                 $this->runTransactionListenerCallbacks( self::TRIGGER_COMMIT );
3073         }
3074
3075         /**
3076          * Issues the COMMIT command to the database server.
3077          *
3078          * @see Database::commit()
3079          * @param string $fname
3080          */
3081         protected function doCommit( $fname ) {
3082                 if ( $this->mTrxLevel ) {
3083                         $this->query( 'COMMIT', $fname );
3084                         $this->mTrxLevel = 0;
3085                 }
3086         }
3087
3088         final public function rollback( $fname = __METHOD__, $flush = '' ) {
3089                 if ( $flush === self::FLUSHING_INTERNAL || $flush === self::FLUSHING_ALL_PEERS ) {
3090                         if ( !$this->mTrxLevel ) {
3091                                 return; // nothing to do
3092                         }
3093                 } else {
3094                         if ( !$this->mTrxLevel ) {
3095                                 $this->queryLogger->error(
3096                                         "$fname: No transaction to rollback, something got out of sync." );
3097                                 return; // nothing to do
3098                         } elseif ( $this->getFlag( self::DBO_TRX ) ) {
3099                                 throw new DBUnexpectedError(
3100                                         $this,
3101                                         "$fname: Expected mass rollback of all peer databases (DBO_TRX set)."
3102                                 );
3103                         }
3104                 }
3105
3106                 // Avoid fatals if close() was called
3107                 $this->assertOpen();
3108
3109                 $this->doRollback( $fname );
3110                 $this->mTrxAtomicLevels = [];
3111                 if ( $this->mTrxDoneWrites ) {
3112                         $this->trxProfiler->transactionWritingOut(
3113                                 $this->mServer,
3114                                 $this->mDBname,
3115                                 $this->mTrxShortId
3116                         );
3117                 }
3118
3119                 $this->mTrxIdleCallbacks = []; // clear
3120                 $this->mTrxPreCommitCallbacks = []; // clear
3121                 try {
3122                         $this->runOnTransactionIdleCallbacks( self::TRIGGER_ROLLBACK );
3123                 } catch ( Exception $e ) {
3124                         // already logged; finish and let LoadBalancer move on during mass-rollback
3125                 }
3126                 try {
3127                         $this->runTransactionListenerCallbacks( self::TRIGGER_ROLLBACK );
3128                 } catch ( Exception $e ) {
3129                         // already logged; let LoadBalancer move on during mass-rollback
3130                 }
3131         }
3132
3133         /**
3134          * Issues the ROLLBACK command to the database server.
3135          *
3136          * @see Database::rollback()
3137          * @param string $fname
3138          */
3139         protected function doRollback( $fname ) {
3140                 if ( $this->mTrxLevel ) {
3141                         # Disconnects cause rollback anyway, so ignore those errors
3142                         $ignoreErrors = true;
3143                         $this->query( 'ROLLBACK', $fname, $ignoreErrors );
3144                         $this->mTrxLevel = 0;
3145                 }
3146         }
3147
3148         public function flushSnapshot( $fname = __METHOD__ ) {
3149                 if ( $this->writesOrCallbacksPending() || $this->explicitTrxActive() ) {
3150                         // This only flushes transactions to clear snapshots, not to write data
3151                         $fnames = implode( ', ', $this->pendingWriteAndCallbackCallers() );
3152                         throw new DBUnexpectedError(
3153                                 $this,
3154                                 "$fname: Cannot flush snapshot because writes are pending ($fnames)."
3155                         );
3156                 }
3157
3158                 $this->commit( $fname, self::FLUSHING_INTERNAL );
3159         }
3160
3161         public function explicitTrxActive() {
3162                 return $this->mTrxLevel && ( $this->mTrxAtomicLevels || !$this->mTrxAutomatic );
3163         }
3164
3165         public function duplicateTableStructure(
3166                 $oldName, $newName, $temporary = false, $fname = __METHOD__
3167         ) {
3168                 throw new RuntimeException( __METHOD__ . ' is not implemented in descendant class' );
3169         }
3170
3171         public function listTables( $prefix = null, $fname = __METHOD__ ) {
3172                 throw new RuntimeException( __METHOD__ . ' is not implemented in descendant class' );
3173         }
3174
3175         public function listViews( $prefix = null, $fname = __METHOD__ ) {
3176                 throw new RuntimeException( __METHOD__ . ' is not implemented in descendant class' );
3177         }
3178
3179         public function timestamp( $ts = 0 ) {
3180                 $t = new ConvertibleTimestamp( $ts );
3181                 // Let errors bubble up to avoid putting garbage in the DB
3182                 return $t->getTimestamp( TS_MW );
3183         }
3184
3185         public function timestampOrNull( $ts = null ) {
3186                 if ( is_null( $ts ) ) {
3187                         return null;
3188                 } else {
3189                         return $this->timestamp( $ts );
3190                 }
3191         }
3192
3193         /**
3194          * Take the result from a query, and wrap it in a ResultWrapper if
3195          * necessary. Boolean values are passed through as is, to indicate success
3196          * of write queries or failure.
3197          *
3198          * Once upon a time, Database::query() returned a bare MySQL result
3199          * resource, and it was necessary to call this function to convert it to
3200          * a wrapper. Nowadays, raw database objects are never exposed to external
3201          * callers, so this is unnecessary in external code.
3202          *
3203          * @param bool|ResultWrapper|resource|object $result
3204          * @return bool|ResultWrapper
3205          */
3206         protected function resultObject( $result ) {
3207                 if ( !$result ) {
3208                         return false;
3209                 } elseif ( $result instanceof ResultWrapper ) {
3210                         return $result;
3211                 } elseif ( $result === true ) {
3212                         // Successful write query
3213                         return $result;
3214                 } else {
3215                         return new ResultWrapper( $this, $result );
3216                 }
3217         }
3218
3219         public function ping( &$rtt = null ) {
3220                 // Avoid hitting the server if it was hit recently
3221                 if ( $this->isOpen() && ( microtime( true ) - $this->lastPing ) < self::PING_TTL ) {
3222                         if ( !func_num_args() || $this->mRTTEstimate > 0 ) {
3223                                 $rtt = $this->mRTTEstimate;
3224                                 return true; // don't care about $rtt
3225                         }
3226                 }
3227
3228                 // This will reconnect if possible or return false if not
3229                 $this->clearFlag( self::DBO_TRX, self::REMEMBER_PRIOR );
3230                 $ok = ( $this->query( self::PING_QUERY, __METHOD__, true ) !== false );
3231                 $this->restoreFlags( self::RESTORE_PRIOR );
3232
3233                 if ( $ok ) {
3234                         $rtt = $this->mRTTEstimate;
3235                 }
3236
3237                 return $ok;
3238         }
3239
3240         /**
3241          * Close existing database connection and open a new connection
3242          *
3243          * @return bool True if new connection is opened successfully, false if error
3244          */
3245         protected function reconnect() {
3246                 $this->closeConnection();
3247                 $this->mOpened = false;
3248                 $this->mConn = false;
3249                 try {
3250                         $this->open( $this->mServer, $this->mUser, $this->mPassword, $this->mDBname );
3251                         $this->lastPing = microtime( true );
3252                         $ok = true;
3253                 } catch ( DBConnectionError $e ) {
3254                         $ok = false;
3255                 }
3256
3257                 return $ok;
3258         }
3259
3260         public function getSessionLagStatus() {
3261                 return $this->getTransactionLagStatus() ?: $this->getApproximateLagStatus();
3262         }
3263
3264         /**
3265          * Get the replica DB lag when the current transaction started
3266          *
3267          * This is useful when transactions might use snapshot isolation
3268          * (e.g. REPEATABLE-READ in innodb), so the "real" lag of that data
3269          * is this lag plus transaction duration. If they don't, it is still
3270          * safe to be pessimistic. This returns null if there is no transaction.
3271          *
3272          * @return array|null ('lag': seconds or false on error, 'since': UNIX timestamp of BEGIN)
3273          * @since 1.27
3274          */
3275         protected function getTransactionLagStatus() {
3276                 return $this->mTrxLevel
3277                         ? [ 'lag' => $this->mTrxReplicaLag, 'since' => $this->trxTimestamp() ]
3278                         : null;
3279         }
3280
3281         /**
3282          * Get a replica DB lag estimate for this server
3283          *
3284          * @return array ('lag': seconds or false on error, 'since': UNIX timestamp of estimate)
3285          * @since 1.27
3286          */
3287         protected function getApproximateLagStatus() {
3288                 return [
3289                         'lag'   => $this->getLBInfo( 'replica' ) ? $this->getLag() : 0,
3290                         'since' => microtime( true )
3291                 ];
3292         }
3293
3294         /**
3295          * Merge the result of getSessionLagStatus() for several DBs
3296          * using the most pessimistic values to estimate the lag of
3297          * any data derived from them in combination
3298          *
3299          * This is information is useful for caching modules
3300          *
3301          * @see WANObjectCache::set()
3302          * @see WANObjectCache::getWithSetCallback()
3303          *
3304          * @param IDatabase $db1
3305          * @param IDatabase $db2 [optional]
3306          * @return array Map of values:
3307          *   - lag: highest lag of any of the DBs or false on error (e.g. replication stopped)
3308          *   - since: oldest UNIX timestamp of any of the DB lag estimates
3309          *   - pending: whether any of the DBs have uncommitted changes
3310          * @throws DBError
3311          * @since 1.27
3312          */
3313         public static function getCacheSetOptions( IDatabase $db1, IDatabase $db2 = null ) {
3314                 $res = [ 'lag' => 0, 'since' => INF, 'pending' => false ];
3315                 foreach ( func_get_args() as $db ) {
3316                         /** @var IDatabase $db */
3317                         $status = $db->getSessionLagStatus();
3318                         if ( $status['lag'] === false ) {
3319                                 $res['lag'] = false;
3320                         } elseif ( $res['lag'] !== false ) {
3321                                 $res['lag'] = max( $res['lag'], $status['lag'] );
3322                         }
3323                         $res['since'] = min( $res['since'], $status['since'] );
3324                         $res['pending'] = $res['pending'] ?: $db->writesPending();
3325                 }
3326
3327                 return $res;
3328         }
3329
3330         public function getLag() {
3331                 return 0;
3332         }
3333
3334         public function maxListLen() {
3335                 return 0;
3336         }
3337
3338         public function encodeBlob( $b ) {
3339                 return $b;
3340         }
3341
3342         public function decodeBlob( $b ) {
3343                 if ( $b instanceof Blob ) {
3344                         $b = $b->fetch();
3345                 }
3346                 return $b;
3347         }
3348
3349         public function setSessionOptions( array $options ) {
3350         }
3351
3352         public function sourceFile(
3353                 $filename,
3354                 callable $lineCallback = null,
3355                 callable $resultCallback = null,
3356                 $fname = false,
3357                 callable $inputCallback = null
3358         ) {
3359                 MediaWiki\suppressWarnings();
3360                 $fp = fopen( $filename, 'r' );
3361                 MediaWiki\restoreWarnings();
3362
3363                 if ( false === $fp ) {
3364                         throw new RuntimeException( "Could not open \"{$filename}\".\n" );
3365                 }
3366
3367                 if ( !$fname ) {
3368                         $fname = __METHOD__ . "( $filename )";
3369                 }
3370
3371                 try {
3372                         $error = $this->sourceStream(
3373                                 $fp, $lineCallback, $resultCallback, $fname, $inputCallback );
3374                 } catch ( Exception $e ) {
3375                         fclose( $fp );
3376                         throw $e;
3377                 }
3378
3379                 fclose( $fp );
3380
3381                 return $error;
3382         }
3383
3384         public function setSchemaVars( $vars ) {
3385                 $this->mSchemaVars = $vars;
3386         }
3387
3388         public function sourceStream(
3389                 $fp,
3390                 callable $lineCallback = null,
3391                 callable $resultCallback = null,
3392                 $fname = __METHOD__,
3393                 callable $inputCallback = null
3394         ) {
3395                 $cmd = '';
3396
3397                 while ( !feof( $fp ) ) {
3398                         if ( $lineCallback ) {
3399                                 call_user_func( $lineCallback );
3400                         }
3401
3402                         $line = trim( fgets( $fp ) );
3403
3404                         if ( $line == '' ) {
3405                                 continue;
3406                         }
3407
3408                         if ( '-' == $line[0] && '-' == $line[1] ) {
3409                                 continue;
3410                         }
3411
3412                         if ( $cmd != '' ) {
3413                                 $cmd .= ' ';
3414                         }
3415
3416                         $done = $this->streamStatementEnd( $cmd, $line );
3417
3418                         $cmd .= "$line\n";
3419
3420                         if ( $done || feof( $fp ) ) {
3421                                 $cmd = $this->replaceVars( $cmd );
3422
3423                                 if ( !$inputCallback || call_user_func( $inputCallback, $cmd ) ) {
3424                                         $res = $this->query( $cmd, $fname );
3425
3426                                         if ( $resultCallback ) {
3427                                                 call_user_func( $resultCallback, $res, $this );
3428                                         }
3429
3430                                         if ( false === $res ) {
3431                                                 $err = $this->lastError();
3432
3433                                                 return "Query \"{$cmd}\" failed with error code \"$err\".\n";
3434                                         }
3435                                 }
3436                                 $cmd = '';
3437                         }
3438                 }
3439
3440                 return true;
3441         }
3442
3443         /**
3444          * Called by sourceStream() to check if we've reached a statement end
3445          *
3446          * @param string &$sql SQL assembled so far
3447          * @param string &$newLine New line about to be added to $sql
3448          * @return bool Whether $newLine contains end of the statement
3449          */
3450         public function streamStatementEnd( &$sql, &$newLine ) {
3451                 if ( $this->delimiter ) {
3452                         $prev = $newLine;
3453                         $newLine = preg_replace(
3454                                 '/' . preg_quote( $this->delimiter, '/' ) . '$/', '', $newLine );
3455                         if ( $newLine != $prev ) {
3456                                 return true;
3457                         }
3458                 }
3459
3460                 return false;
3461         }
3462
3463         /**
3464          * Database independent variable replacement. Replaces a set of variables
3465          * in an SQL statement with their contents as given by $this->getSchemaVars().
3466          *
3467          * Supports '{$var}' `{$var}` and / *$var* / (without the spaces) style variables.
3468          *
3469          * - '{$var}' should be used for text and is passed through the database's
3470          *   addQuotes method.
3471          * - `{$var}` should be used for identifiers (e.g. table and database names).
3472          *   It is passed through the database's addIdentifierQuotes method which
3473          *   can be overridden if the database uses something other than backticks.
3474          * - / *_* / or / *$wgDBprefix* / passes the name that follows through the
3475          *   database's tableName method.
3476          * - / *i* / passes the name that follows through the database's indexName method.
3477          * - In all other cases, / *$var* / is left unencoded. Except for table options,
3478          *   its use should be avoided. In 1.24 and older, string encoding was applied.
3479          *
3480          * @param string $ins SQL statement to replace variables in
3481          * @return string The new SQL statement with variables replaced
3482          */
3483         protected function replaceVars( $ins ) {
3484                 $vars = $this->getSchemaVars();
3485                 return preg_replace_callback(
3486                         '!
3487                                 /\* (\$wgDBprefix|[_i]) \*/ (\w*) | # 1-2. tableName, indexName
3488                                 \'\{\$ (\w+) }\'                  | # 3. addQuotes
3489                                 `\{\$ (\w+) }`                    | # 4. addIdentifierQuotes
3490                                 /\*\$ (\w+) \*/                     # 5. leave unencoded
3491                         !x',
3492                         function ( $m ) use ( $vars ) {
3493                                 // Note: Because of <https://bugs.php.net/bug.php?id=51881>,
3494                                 // check for both nonexistent keys *and* the empty string.
3495                                 if ( isset( $m[1] ) && $m[1] !== '' ) {
3496                                         if ( $m[1] === 'i' ) {
3497                                                 return $this->indexName( $m[2] );
3498                                         } else {
3499                                                 return $this->tableName( $m[2] );
3500                                         }
3501                                 } elseif ( isset( $m[3] ) && $m[3] !== '' && array_key_exists( $m[3], $vars ) ) {
3502                                         return $this->addQuotes( $vars[$m[3]] );
3503                                 } elseif ( isset( $m[4] ) && $m[4] !== '' && array_key_exists( $m[4], $vars ) ) {
3504                                         return $this->addIdentifierQuotes( $vars[$m[4]] );
3505                                 } elseif ( isset( $m[5] ) && $m[5] !== '' && array_key_exists( $m[5], $vars ) ) {
3506                                         return $vars[$m[5]];
3507                                 } else {
3508                                         return $m[0];
3509                                 }
3510                         },
3511                         $ins
3512                 );
3513         }
3514
3515         /**
3516          * Get schema variables. If none have been set via setSchemaVars(), then
3517          * use some defaults from the current object.
3518          *
3519          * @return array
3520          */
3521         protected function getSchemaVars() {
3522                 if ( $this->mSchemaVars ) {
3523                         return $this->mSchemaVars;
3524                 } else {
3525                         return $this->getDefaultSchemaVars();
3526                 }
3527         }
3528
3529         /**
3530          * Get schema variables to use if none have been set via setSchemaVars().
3531          *
3532          * Override this in derived classes to provide variables for tables.sql
3533          * and SQL patch files.
3534          *
3535          * @return array
3536          */
3537         protected function getDefaultSchemaVars() {
3538                 return [];
3539         }
3540
3541         public function lockIsFree( $lockName, $method ) {
3542                 return true;
3543         }
3544
3545         public function lock( $lockName, $method, $timeout = 5 ) {
3546                 $this->mNamedLocksHeld[$lockName] = 1;
3547
3548                 return true;
3549         }
3550
3551         public function unlock( $lockName, $method ) {
3552                 unset( $this->mNamedLocksHeld[$lockName] );
3553
3554                 return true;
3555         }
3556
3557         public function getScopedLockAndFlush( $lockKey, $fname, $timeout ) {
3558                 if ( $this->writesOrCallbacksPending() ) {
3559                         // This only flushes transactions to clear snapshots, not to write data
3560                         $fnames = implode( ', ', $this->pendingWriteAndCallbackCallers() );
3561                         throw new DBUnexpectedError(
3562                                 $this,
3563                                 "$fname: Cannot flush pre-lock snapshot because writes are pending ($fnames)."
3564                         );
3565                 }
3566
3567                 if ( !$this->lock( $lockKey, $fname, $timeout ) ) {
3568                         return null;
3569                 }
3570
3571                 $unlocker = new ScopedCallback( function () use ( $lockKey, $fname ) {
3572                         if ( $this->trxLevel() ) {
3573                                 // There is a good chance an exception was thrown, causing any early return
3574                                 // from the caller. Let any error handler get a chance to issue rollback().
3575                                 // If there isn't one, let the error bubble up and trigger server-side rollback.
3576                                 $this->onTransactionResolution(
3577                                         function () use ( $lockKey, $fname ) {
3578                                                 $this->unlock( $lockKey, $fname );
3579                                         },
3580                                         $fname
3581                                 );
3582                         } else {
3583                                 $this->unlock( $lockKey, $fname );
3584                         }
3585                 } );
3586
3587                 $this->commit( $fname, self::FLUSHING_INTERNAL );
3588
3589                 return $unlocker;
3590         }
3591
3592         public function namedLocksEnqueue() {
3593                 return false;
3594         }
3595
3596         public function tableLocksHaveTransactionScope() {
3597                 return true;
3598         }
3599
3600         final public function lockTables( array $read, array $write, $method ) {
3601                 if ( $this->writesOrCallbacksPending() ) {
3602                         throw new DBUnexpectedError( $this, "Transaction writes or callbacks still pending." );
3603                 }
3604
3605                 if ( $this->tableLocksHaveTransactionScope() ) {
3606                         $this->startAtomic( $method );
3607                 }
3608
3609                 return $this->doLockTables( $read, $write, $method );
3610         }
3611
3612         /**
3613          * Helper function for lockTables() that handles the actual table locking
3614          *
3615          * @param array $read Array of tables to lock for read access
3616          * @param array $write Array of tables to lock for write access
3617          * @param string $method Name of caller
3618          * @return true
3619          */
3620         protected function doLockTables( array $read, array $write, $method ) {
3621                 return true;
3622         }
3623
3624         final public function unlockTables( $method ) {
3625                 if ( $this->tableLocksHaveTransactionScope() ) {
3626                         $this->endAtomic( $method );
3627
3628                         return true; // locks released on COMMIT/ROLLBACK
3629                 }
3630
3631                 return $this->doUnlockTables( $method );
3632         }
3633
3634         /**
3635          * Helper function for unlockTables() that handles the actual table unlocking
3636          *
3637          * @param string $method Name of caller
3638          * @return true
3639          */
3640         protected function doUnlockTables( $method ) {
3641                 return true;
3642         }
3643
3644         /**
3645          * Delete a table
3646          * @param string $tableName
3647          * @param string $fName
3648          * @return bool|ResultWrapper
3649          * @since 1.18
3650          */
3651         public function dropTable( $tableName, $fName = __METHOD__ ) {
3652                 if ( !$this->tableExists( $tableName, $fName ) ) {
3653                         return false;
3654                 }
3655                 $sql = "DROP TABLE " . $this->tableName( $tableName ) . " CASCADE";
3656
3657                 return $this->query( $sql, $fName );
3658         }
3659
3660         public function getInfinity() {
3661                 return 'infinity';
3662         }
3663
3664         public function encodeExpiry( $expiry ) {
3665                 return ( $expiry == '' || $expiry == 'infinity' || $expiry == $this->getInfinity() )
3666                         ? $this->getInfinity()
3667                         : $this->timestamp( $expiry );
3668         }
3669
3670         public function decodeExpiry( $expiry, $format = TS_MW ) {
3671                 if ( $expiry == '' || $expiry == 'infinity' || $expiry == $this->getInfinity() ) {
3672                         return 'infinity';
3673                 }
3674
3675                 return ConvertibleTimestamp::convert( $format, $expiry );
3676         }
3677
3678         public function setBigSelects( $value = true ) {
3679                 // no-op
3680         }
3681
3682         public function isReadOnly() {
3683                 return ( $this->getReadOnlyReason() !== false );
3684         }
3685
3686         /**
3687          * @return string|bool Reason this DB is read-only or false if it is not
3688          */
3689         protected function getReadOnlyReason() {
3690                 $reason = $this->getLBInfo( 'readOnlyReason' );
3691
3692                 return is_string( $reason ) ? $reason : false;
3693         }
3694
3695         public function setTableAliases( array $aliases ) {
3696                 $this->tableAliases = $aliases;
3697         }
3698
3699         /**
3700          * @return bool Whether a DB user is required to access the DB
3701          * @since 1.28
3702          */
3703         protected function requiresDatabaseUser() {
3704                 return true;
3705         }
3706
3707         /**
3708          * Get the underlying binding handle, mConn
3709          *
3710          * Makes sure that mConn is set (disconnects and ping() failure can unset it).
3711          * This catches broken callers than catch and ignore disconnection exceptions.
3712          * Unlike checking isOpen(), this is safe to call inside of open().
3713          *
3714          * @return resource|object
3715          * @throws DBUnexpectedError
3716          * @since 1.26
3717          */
3718         protected function getBindingHandle() {
3719                 if ( !$this->mConn ) {
3720                         throw new DBUnexpectedError(
3721                                 $this,
3722                                 'DB connection was already closed or the connection dropped.'
3723                         );
3724                 }
3725
3726                 return $this->mConn;
3727         }
3728
3729         /**
3730          * @since 1.19
3731          * @return string
3732          */
3733         public function __toString() {
3734                 return (string)$this->mConn;
3735         }
3736
3737         /**
3738          * Make sure that copies do not share the same client binding handle
3739          * @throws DBConnectionError
3740          */
3741         public function __clone() {
3742                 $this->connLogger->warning(
3743                         "Cloning " . static::class . " is not recomended; forking connection:\n" .
3744                         ( new RuntimeException() )->getTraceAsString()
3745                 );
3746
3747                 if ( $this->isOpen() ) {
3748                         // Open a new connection resource without messing with the old one
3749                         $this->mOpened = false;
3750                         $this->mConn = false;
3751                         $this->mTrxEndCallbacks = []; // don't copy
3752                         $this->handleSessionLoss(); // no trx or locks anymore
3753                         $this->open( $this->mServer, $this->mUser, $this->mPassword, $this->mDBname );
3754                         $this->lastPing = microtime( true );
3755                 }
3756         }
3757
3758         /**
3759          * Called by serialize. Throw an exception when DB connection is serialized.
3760          * This causes problems on some database engines because the connection is
3761          * not restored on unserialize.
3762          */
3763         public function __sleep() {
3764                 throw new RuntimeException( 'Database serialization may cause problems, since ' .
3765                         'the connection is not restored on wakeup.' );
3766         }
3767
3768         /**
3769          * Run a few simple sanity checks and close dangling connections
3770          */
3771         public function __destruct() {
3772                 if ( $this->mTrxLevel && $this->mTrxDoneWrites ) {
3773                         trigger_error( "Uncommitted DB writes (transaction from {$this->mTrxFname})." );
3774                 }
3775
3776                 $danglingWriters = $this->pendingWriteAndCallbackCallers();
3777                 if ( $danglingWriters ) {
3778                         $fnames = implode( ', ', $danglingWriters );
3779                         trigger_error( "DB transaction writes or callbacks still pending ($fnames)." );
3780                 }
3781
3782                 if ( $this->mConn ) {
3783                         // Avoid connection leaks for sanity. Normally, resources close at script completion.
3784                         // The connection might already be closed in zend/hhvm by now, so suppress warnings.
3785                         \MediaWiki\suppressWarnings();
3786                         $this->closeConnection();
3787                         \MediaWiki\restoreWarnings();
3788                         $this->mConn = false;
3789                         $this->mOpened = false;
3790                 }
3791         }
3792 }
3793
3794 class_alias( Database::class, 'DatabaseBase' ); // b/c for old name
3795 class_alias( Database::class, 'Database' ); // b/c global alias