includes/libs/rdbms/database/Database.php

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