includes/libs/rdbms/database/Database.php

   1 <?php
   2 /**
   3  * @defgroup Database Database
   4  *
   5  * This file deals with database interface functions
   6  * and query specifics/optimisations.
   7  *
   8  * This program is free software; you can redistribute it and/or modify
   9  * it under the terms of the GNU General Public License as published by
  10  * the Free Software Foundation; either version 2 of the License, or
  11  * (at your option) any later version.
  12  *
  13  * This program is distributed in the hope that it will be useful,
  14  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  15  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
  16  * GNU General Public License for more details.
  17  *
  18  * You should have received a copy of the GNU General Public License along
  19  * with this program; if not, write to the Free Software Foundation, Inc.,
  20  * 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
  21  * http://www.gnu.org/copyleft/gpl.html
  22  *
  23  * @file
  24  * @ingroup Database
  25  */
  26 namespace Wikimedia\Rdbms;
  27
  28 use Psr\Log\LoggerAwareInterface;
  29 use Psr\Log\LoggerInterface;
  30 use Wikimedia\ScopedCallback;
  31 use Wikimedia\Timestamp\ConvertibleTimestamp;
  32 use MediaWiki;
  33 use BagOStuff;
  34 use HashBagOStuff;
  35 use InvalidArgumentException;
  36 use Exception;
  37 use RuntimeException;
  38
  39 /**
  40  * Relational database abstraction object
  41  *
  42  * @ingroup Database
  43  * @since 1.28
  44  */
  45 abstract class Database implements IDatabase, IMaintainableDatabase, LoggerAwareInterface {
  46         /** Number of times to re-try an operation in case of deadlock */
  47         const DEADLOCK_TRIES = 4;
  48         /** Minimum time to wait before retry, in microseconds */
  49         const DEADLOCK_DELAY_MIN = 500000;
  50         /** Maximum time to wait before retry */
  51         const DEADLOCK_DELAY_MAX = 1500000;
  52
  53         /** How long before it is worth doing a dummy query to test the connection */
  54         const PING_TTL = 1.0;
  55         const PING_QUERY = 'SELECT 1 AS ping';
  56
  57         const TINY_WRITE_SEC = .010;
  58         const SLOW_WRITE_SEC = .500;
  59         const SMALL_WRITE_ROWS = 100;
  60
  61         /** @var string SQL query */
  62         protected $mLastQuery = '';
  63         /** @var float|bool UNIX timestamp of last write query */
  64         protected $mLastWriteTime = false;
  65         /** @var string|bool */
  66         protected $mPHPError = false;
  67         /** @var string */
  68         protected $mServer;
  69         /** @var string */
  70         protected $mUser;
  71         /** @var string */
  72         protected $mPassword;
  73         /** @var string */
  74         protected $mDBname;
  75         /** @var array[] $aliases Map of (table => (dbname, schema, prefix) map) */
  76         protected $tableAliases = [];
  77         /** @var bool Whether this PHP instance is for a CLI script */
  78         protected $cliMode;
  79         /** @var string Agent name for query profiling */
  80         protected $agent;
  81
  82         /** @var BagOStuff APC cache */
  83         protected $srvCache;
  84         /** @var LoggerInterface */
  85         protected $connLogger;
  86         /** @var LoggerInterface */
  87         protected $queryLogger;
  88         /** @var callback Error logging callback */
  89         protected $errorLogger;
  90
  91         /** @var resource|null Database connection */
  92         protected $mConn = null;
  93         /** @var bool */
  94         protected $mOpened = false;
  95
  96         /** @var array[] List of (callable, method name) */
  97         protected $mTrxIdleCallbacks = [];
  98         /** @var array[] List of (callable, method name) */
  99         protected $mTrxPreCommitCallbacks = [];
 100         /** @var array[] List of (callable, method name) */
 101         protected $mTrxEndCallbacks = [];
 102         /** @var callable[] Map of (name => callable) */
 103         protected $mTrxRecurringCallbacks = [];
 104         /** @var bool Whether to suppress triggering of transaction end callbacks */
 105         protected $mTrxEndCallbacksSuppressed = false;
 106
 107         /** @var string */
 108         protected $mTablePrefix = '';
 109         /** @var string */
 110         protected $mSchema = '';
 111         /** @var integer */
 112         protected $mFlags;
 113         /** @var array */
 114         protected $mLBInfo = [];
 115         /** @var bool|null */
 116         protected $mDefaultBigSelects = null;
 117         /** @var array|bool */
 118         protected $mSchemaVars = false;
 119         /** @var array */
 120         protected $mSessionVars = [];
 121         /** @var array|null */
 122         protected $preparedArgs;
 123         /** @var string|bool|null Stashed value of html_errors INI setting */
 124         protected $htmlErrors;
 125         /** @var string */
 126         protected $delimiter = ';';
 127         /** @var DatabaseDomain */
 128         protected $currentDomain;
 129
 130         /**
 131          * Either 1 if a transaction is active or 0 otherwise.
 132          * The other Trx fields may not be meaningfull if this is 0.
 133          *
 134          * @var int
 135          */
 136         protected $mTrxLevel = 0;
 137         /**
 138          * Either a short hexidecimal string if a transaction is active or ""
 139          *
 140          * @var string
 141          * @see Database::mTrxLevel
 142          */
 143         protected $mTrxShortId = '';
 144         /**
 145          * The UNIX time that the transaction started. Callers can assume that if
 146          * snapshot isolation is used, then the data is *at least* up to date to that
 147          * point (possibly more up-to-date since the first SELECT defines the snapshot).
 148          *
 149          * @var float|null
 150          * @see Database::mTrxLevel
 151          */
 152         private $mTrxTimestamp = null;
 153         /** @var float Lag estimate at the time of BEGIN */
 154         private $mTrxReplicaLag = null;
 155         /**
 156          * Remembers the function name given for starting the most recent transaction via begin().
 157          * Used to provide additional context for error reporting.
 158          *
 159          * @var string
 160          * @see Database::mTrxLevel
 161          */
 162         private $mTrxFname = null;
 163         /**
 164          * Record if possible write queries were done in the last transaction started
 165          *
 166          * @var bool
 167          * @see Database::mTrxLevel
 168          */
 169         private $mTrxDoneWrites = false;
 170         /**
 171          * Record if the current transaction was started implicitly due to DBO_TRX being set.
 172          *
 173          * @var bool
 174          * @see Database::mTrxLevel
 175          */
 176         private $mTrxAutomatic = false;
 177         /**
 178          * Array of levels of atomicity within transactions
 179          *
 180          * @var array
 181          */
 182         private $mTrxAtomicLevels = [];
 183         /**
 184          * Record if the current transaction was started implicitly by Database::startAtomic
 185          *
 186          * @var bool
 187          */
 188         private $mTrxAutomaticAtomic = false;
 189         /**
 190          * Track the write query callers of the current transaction
 191          *
 192          * @var string[]
 193          */
 194         private $mTrxWriteCallers = [];
 195         /**
 196          * @var float Seconds spent in write queries for the current transaction
 197          */
 198         private $mTrxWriteDuration = 0.0;
 199         /**
 200          * @var integer Number of write queries for the current transaction
 201          */
 202         private $mTrxWriteQueryCount = 0;
 203         /**
 204          * @var float Like mTrxWriteQueryCount but excludes lock-bound, easy to replicate, queries
 205          */
 206         private $mTrxWriteAdjDuration = 0.0;
 207         /**
 208          * @var integer Number of write queries counted in mTrxWriteAdjDuration
 209          */
 210         private $mTrxWriteAdjQueryCount = 0;
 211         /**
 212          * @var float RTT time estimate
 213          */
 214         private $mRTTEstimate = 0.0;
 215
 216         /** @var array Map of (name => 1) for locks obtained via lock() */
 217         private $mNamedLocksHeld = [];
 218         /** @var array Map of (table name => 1) for TEMPORARY tables */
 219         protected $mSessionTempTables = [];
 220
 221         /** @var IDatabase|null Lazy handle to the master DB this server replicates from */
 222         private $lazyMasterHandle;
 223
 224         /** @var float UNIX timestamp */
 225         protected $lastPing = 0.0;
 226
 227         /** @var int[] Prior mFlags values */
 228         private $priorFlags = [];
 229
 230         /** @var object|string Class name or object With profileIn/profileOut methods */
 231         protected $profiler;
 232         /** @var TransactionProfiler */
 233         protected $trxProfiler;
 234
 235         /**
 236          * Constructor and database handle and attempt to connect to the DB server
 237          *
 238          * IDatabase classes should not be constructed directly in external
 239          * code. Database::factory() should be used instead.
 240          *
 241          * @param array $params Parameters passed from Database::factory()
 242          */
 243         function __construct( array $params ) {
 244                 $server = $params['host'];
 245                 $user = $params['user'];
 246                 $password = $params['password'];
 247                 $dbName = $params['dbname'];
 248
 249                 $this->mSchema = $params['schema'];
 250                 $this->mTablePrefix = $params['tablePrefix'];
 251
 252                 $this->cliMode = $params['cliMode'];
 253                 // Agent name is added to SQL queries in a comment, so make sure it can't break out
 254                 $this->agent = str_replace( '/', '-', $params['agent'] );
 255
 256                 $this->mFlags = $params['flags'];
 257                 if ( $this->mFlags & self::DBO_DEFAULT ) {
 258                         if ( $this->cliMode ) {
 259                                 $this->mFlags &= ~self::DBO_TRX;
 260                         } else {
 261                                 $this->mFlags |= self::DBO_TRX;
 262                         }
 263                 }
 264
 265                 $this->mSessionVars = $params['variables'];
 266
 267                 $this->srvCache = isset( $params['srvCache'] )
 268                         ? $params['srvCache']
 269                         : new HashBagOStuff();
 270
 271                 $this->profiler = $params['profiler'];
 272                 $this->trxProfiler = $params['trxProfiler'];
 273                 $this->connLogger = $params['connLogger'];
 274                 $this->queryLogger = $params['queryLogger'];
 275                 $this->errorLogger = $params['errorLogger'];
 276
 277                 // Set initial dummy domain until open() sets the final DB/prefix
 278                 $this->currentDomain = DatabaseDomain::newUnspecified();
 279
 280                 if ( $user ) {
 281                         $this->open( $server, $user, $password, $dbName );
 282                 } elseif ( $this->requiresDatabaseUser() ) {
 283                         throw new InvalidArgumentException( "No database user provided." );
 284                 }
 285
 286                 // Set the domain object after open() sets the relevant fields
 287                 if ( $this->mDBname != '' ) {
 288                         // Domains with server scope but a table prefix are not used by IDatabase classes
 289                         $this->currentDomain = new DatabaseDomain( $this->mDBname, null, $this->mTablePrefix );
 290                 }
 291         }
 292
 293         /**
 294          * Construct a Database subclass instance given a database type and parameters
 295          *
 296          * This also connects to the database immediately upon object construction
 297          *
 298          * @param string $dbType A possible DB type (sqlite, mysql, postgres)
 299          * @param array $p Parameter map with keys:
 300          *   - host : The hostname of the DB server
 301          *   - user : The name of the database user the client operates under
 302          *   - password : The password for the database user
 303          *   - dbname : The name of the database to use where queries do not specify one.
 304          *      The database must exist or an error might be thrown. Setting this to the empty string
 305          *      will avoid any such errors and make the handle have no implicit database scope. This is
 306          *      useful for queries like SHOW STATUS, CREATE DATABASE, or DROP DATABASE. Note that a
 307          *      "database" in Postgres is rougly equivalent to an entire MySQL server. This the domain
 308          *      in which user names and such are defined, e.g. users are database-specific in Postgres.
 309          *   - schema : The database schema to use (if supported). A "schema" in Postgres is roughly
 310          *      equivalent to a "database" in MySQL. Note that MySQL and SQLite do not use schemas.
 311          *   - tablePrefix : Optional table prefix that is implicitly added on to all table names
 312          *      recognized in queries. This can be used in place of schemas for handle site farms.
 313          *   - flags : Optional bitfield of DBO_* constants that define connection, protocol,
 314          *      buffering, and transaction behavior. It is STRONGLY adviced to leave the DBO_DEFAULT
 315          *      flag in place UNLESS this this database simply acts as a key/value store.
 316          *   - driver: Optional name of a specific DB client driver. For MySQL, there is the old
 317          *      'mysql' driver and the newer 'mysqli' driver.
 318          *   - variables: Optional map of session variables to set after connecting. This can be
 319          *      used to adjust lock timeouts or encoding modes and the like.
 320          *   - connLogger: Optional PSR-3 logger interface instance.
 321          *   - queryLogger: Optional PSR-3 logger interface instance.
 322          *   - profiler: Optional class name or object with profileIn()/profileOut() methods.
 323          *      These will be called in query(), using a simplified version of the SQL that also
 324          *      includes the agent as a SQL comment.
 325          *   - trxProfiler: Optional TransactionProfiler instance.
 326          *   - errorLogger: Optional callback that takes an Exception and logs it.
 327          *   - cliMode: Whether to consider the execution context that of a CLI script.
 328          *   - agent: Optional name used to identify the end-user in query profiling/logging.
 329          *   - srvCache: Optional BagOStuff instance to an APC-style cache.
 330          * @return Database|null If the database driver or extension cannot be found
 331          * @throws InvalidArgumentException If the database driver or extension cannot be found
 332          * @since 1.18
 333          */
 334         final public static function factory( $dbType, $p = [] ) {
 335                 static $canonicalDBTypes = [
 336                         'mysql' => [ 'mysqli', 'mysql' ],
 337                         'postgres' => [],
 338                         'sqlite' => [],
 339                         'oracle' => [],
 340                         'mssql' => [],
 341                 ];
 342                 static $classAliases = [
 343                         'DatabaseMssql' => DatabaseMssql::class,
 344                         'DatabaseMysql' => DatabaseMysql::class,
 345                         'DatabaseMysqli' => DatabaseMysqli::class,
 346                         'DatabaseSqlite' => DatabaseSqlite::class,
 347                         'DatabasePostgres' => DatabasePostgres::class
 348                 ];
 349
 350                 $driver = false;
 351                 $dbType = strtolower( $dbType );
 352                 if ( isset( $canonicalDBTypes[$dbType] ) && $canonicalDBTypes[$dbType] ) {
 353                         $possibleDrivers = $canonicalDBTypes[$dbType];
 354                         if ( !empty( $p['driver'] ) ) {
 355                                 if ( in_array( $p['driver'], $possibleDrivers ) ) {
 356                                         $driver = $p['driver'];
 357                                 } else {
 358                                         throw new InvalidArgumentException( __METHOD__ .
 359                                                 " type '$dbType' does not support driver '{$p['driver']}'" );
 360                                 }
 361                         } else {
 362                                 foreach ( $possibleDrivers as $posDriver ) {
 363                                         if ( extension_loaded( $posDriver ) ) {
 364                                                 $driver = $posDriver;
 365                                                 break;
 366                                         }
 367                                 }
 368                         }
 369                 } else {
 370                         $driver = $dbType;
 371                 }
 372
 373                 if ( $driver === false || $driver === '' ) {
 374                         throw new InvalidArgumentException( __METHOD__ .
 375                                 " no viable database extension found for type '$dbType'" );
 376                 }
 377
 378                 $class = 'Database' . ucfirst( $driver );
 379                 if ( isset( $classAliases[$class] ) ) {
 380                         $class = $classAliases[$class];
 381                 }
 382
 383                 if ( class_exists( $class ) && is_subclass_of( $class, IDatabase::class ) ) {
 384                         // Resolve some defaults for b/c
 385                         $p['host'] = isset( $p['host'] ) ? $p['host'] : false;
 386                         $p['user'] = isset( $p['user'] ) ? $p['user'] : false;
 387                         $p['password'] = isset( $p['password'] ) ? $p['password'] : false;
 388                         $p['dbname'] = isset( $p['dbname'] ) ? $p['dbname'] : false;
 389                         $p['flags'] = isset( $p['flags'] ) ? $p['flags'] : 0;
 390                         $p['variables'] = isset( $p['variables'] ) ? $p['variables'] : [];
 391                         $p['tablePrefix'] = isset( $p['tablePrefix'] ) ? $p['tablePrefix'] : '';
 392                         $p['schema'] = isset( $p['schema'] ) ? $p['schema'] : '';
 393                         $p['cliMode'] = isset( $p['cliMode'] ) ? $p['cliMode'] : ( PHP_SAPI === 'cli' );
 394                         $p['agent'] = isset( $p['agent'] ) ? $p['agent'] : '';
 395                         if ( !isset( $p['connLogger'] ) ) {
 396                                 $p['connLogger'] = new \Psr\Log\NullLogger();
 397                         }
 398                         if ( !isset( $p['queryLogger'] ) ) {
 399                                 $p['queryLogger'] = new \Psr\Log\NullLogger();
 400                         }
 401                         $p['profiler'] = isset( $p['profiler'] ) ? $p['profiler'] : null;
 402                         if ( !isset( $p['trxProfiler'] ) ) {
 403                                 $p['trxProfiler'] = new TransactionProfiler();
 404                         }
 405                         if ( !isset( $p['errorLogger'] ) ) {
 406                                 $p['errorLogger'] = function ( Exception $e ) {
 407                                         trigger_error( get_class( $e ) . ': ' . $e->getMessage(), E_USER_WARNING );
 408                                 };
 409                         }
 410
 411                         $conn = new $class( $p );
 412                 } else {
 413                         $conn = null;
 414                 }
 415
 416                 return $conn;
 417         }
 418
 419         /**
 420          * Set the PSR-3 logger interface to use for query logging. (The logger
 421          * interfaces for connection logging and error logging can be set with the
 422          * constructor.)
 423          *
 424          * @param LoggerInterface $logger
 425          */
 426         public function setLogger( LoggerInterface $logger ) {
 427                 $this->queryLogger = $logger;
 428         }
 429
 430         public function getServerInfo() {
 431                 return $this->getServerVersion();
 432         }
 433
 434         public function bufferResults( $buffer = null ) {
 435                 $res = !$this->getFlag( self::DBO_NOBUFFER );
 436                 if ( $buffer !== null ) {
 437                         $buffer
 438                                 ? $this->clearFlag( self::DBO_NOBUFFER )
 439                                 : $this->setFlag( self::DBO_NOBUFFER );
 440                 }
 441
 442                 return $res;
 443         }
 444
 445         /**
 446          * Turns on (false) or off (true) the automatic generation and sending
 447          * of a "we're sorry, but there has been a database error" page on
 448          * database errors. Default is on (false). When turned off, the
 449          * code should use lastErrno() and lastError() to handle the
 450          * situation as appropriate.
 451          *
 452          * Do not use this function outside of the Database classes.
 453          *
 454          * @param null|bool $ignoreErrors
 455          * @return bool The previous value of the flag.
 456          */
 457         protected function ignoreErrors( $ignoreErrors = null ) {
 458                 $res = $this->getFlag( self::DBO_IGNORE );
 459                 if ( $ignoreErrors !== null ) {
 460                         $ignoreErrors
 461                                 ? $this->setFlag( self::DBO_IGNORE )
 462                                 : $this->clearFlag( self::DBO_IGNORE );
 463                 }
 464
 465                 return $res;
 466         }
 467
 468         public function trxLevel() {
 469                 return $this->mTrxLevel;
 470         }
 471
 472         public function trxTimestamp() {
 473                 return $this->mTrxLevel ? $this->mTrxTimestamp : null;
 474         }
 475
 476         public function tablePrefix( $prefix = null ) {
 477                 $old = $this->mTablePrefix;
 478                 if ( $prefix !== null ) {
 479                         $this->mTablePrefix = $prefix;
 480                         $this->currentDomain = ( $this->mDBname != '' )
 481                                 ? new DatabaseDomain( $this->mDBname, null, $this->mTablePrefix )
 482                                 : DatabaseDomain::newUnspecified();
 483                 }
 484
 485                 return $old;
 486         }
 487
 488         public function dbSchema( $schema = null ) {
 489                 $old = $this->mSchema;
 490                 if ( $schema !== null ) {
 491                         $this->mSchema = $schema;
 492                 }
 493
 494                 return $old;
 495         }
 496
 497         public function getLBInfo( $name = null ) {
 498                 if ( is_null( $name ) ) {
 499                         return $this->mLBInfo;
 500                 } else {
 501                         if ( array_key_exists( $name, $this->mLBInfo ) ) {
 502                                 return $this->mLBInfo[$name];
 503                         } else {
 504                                 return null;
 505                         }
 506                 }
 507         }
 508
 509         public function setLBInfo( $name, $value = null ) {
 510                 if ( is_null( $value ) ) {
 511                         $this->mLBInfo = $name;
 512                 } else {
 513                         $this->mLBInfo[$name] = $value;
 514                 }
 515         }
 516
 517         public function setLazyMasterHandle( IDatabase $conn ) {
 518                 $this->lazyMasterHandle = $conn;
 519         }
 520
 521         /**
 522          * @return IDatabase|null
 523          * @see setLazyMasterHandle()
 524          * @since 1.27
 525          */
 526         protected function getLazyMasterHandle() {
 527                 return $this->lazyMasterHandle;
 528         }
 529
 530         public function implicitGroupby() {
 531                 return true;
 532         }
 533
 534         public function implicitOrderby() {
 535                 return true;
 536         }
 537
 538         public function lastQuery() {
 539                 return $this->mLastQuery;
 540         }
 541
 542         public function doneWrites() {
 543                 return (bool)$this->mLastWriteTime;
 544         }
 545
 546         public function lastDoneWrites() {
 547                 return $this->mLastWriteTime ?: false;
 548         }
 549
 550         public function writesPending() {
 551                 return $this->mTrxLevel && $this->mTrxDoneWrites;
 552         }
 553
 554         public function writesOrCallbacksPending() {
 555                 return $this->mTrxLevel && (
 556                         $this->mTrxDoneWrites || $this->mTrxIdleCallbacks || $this->mTrxPreCommitCallbacks
 557                 );
 558         }
 559
 560         public function pendingWriteQueryDuration( $type = self::ESTIMATE_TOTAL ) {
 561                 if ( !$this->mTrxLevel ) {
 562                         return false;
 563                 } elseif ( !$this->mTrxDoneWrites ) {
 564                         return 0.0;
 565                 }
 566
 567                 switch ( $type ) {
 568                         case self::ESTIMATE_DB_APPLY:
 569                                 $this->ping( $rtt );
 570                                 $rttAdjTotal = $this->mTrxWriteAdjQueryCount * $rtt;
 571                                 $applyTime = max( $this->mTrxWriteAdjDuration - $rttAdjTotal, 0 );
 572                                 // For omitted queries, make them count as something at least
 573                                 $omitted = $this->mTrxWriteQueryCount - $this->mTrxWriteAdjQueryCount;
 574                                 $applyTime += self::TINY_WRITE_SEC * $omitted;
 575
 576                                 return $applyTime;
 577                         default: // everything
 578                                 return $this->mTrxWriteDuration;
 579                 }
 580         }
 581
 582         public function pendingWriteCallers() {
 583                 return $this->mTrxLevel ? $this->mTrxWriteCallers : [];
 584         }
 585
 586         /**
 587          * Get the list of method names that have pending write queries or callbacks
 588          * for this transaction
 589          *
 590          * @return array
 591          */
 592         protected function pendingWriteAndCallbackCallers() {
 593                 if ( !$this->mTrxLevel ) {
 594                         return [];
 595                 }
 596
 597                 $fnames = $this->mTrxWriteCallers;
 598                 foreach ( [
 599                         $this->mTrxIdleCallbacks,
 600                         $this->mTrxPreCommitCallbacks,
 601                         $this->mTrxEndCallbacks
 602                 ] as $callbacks ) {
 603                         foreach ( $callbacks as $callback ) {
 604                                 $fnames[] = $callback[1];
 605                         }
 606                 }
 607
 608                 return $fnames;
 609         }
 610
 611         public function isOpen() {
 612                 return $this->mOpened;
 613         }
 614
 615         public function setFlag( $flag, $remember = self::REMEMBER_NOTHING ) {
 616                 if ( $remember === self::REMEMBER_PRIOR ) {
 617                         array_push( $this->priorFlags, $this->mFlags );
 618                 }
 619                 $this->mFlags |= $flag;
 620         }
 621
 622         public function clearFlag( $flag, $remember = self::REMEMBER_NOTHING ) {
 623                 if ( $remember === self::REMEMBER_PRIOR ) {
 624                         array_push( $this->priorFlags, $this->mFlags );
 625                 }
 626                 $this->mFlags &= ~$flag;
 627         }
 628
 629         public function restoreFlags( $state = self::RESTORE_PRIOR ) {
 630                 if ( !$this->priorFlags ) {
 631                         return;
 632                 }
 633
 634                 if ( $state === self::RESTORE_INITIAL ) {
 635                         $this->mFlags = reset( $this->priorFlags );
 636                         $this->priorFlags = [];
 637                 } else {
 638                         $this->mFlags = array_pop( $this->priorFlags );
 639                 }
 640         }
 641
 642         public function getFlag( $flag ) {
 643                 return !!( $this->mFlags & $flag );
 644         }
 645
 646         /**
 647          * @param string $name Class field name
 648          * @return mixed
 649          * @deprecated Since 1.28
 650          */
 651         public function getProperty( $name ) {
 652                 return $this->$name;
 653         }
 654
 655         public function getDomainID() {
 656                 return $this->currentDomain->getId();
 657         }
 658
 659         final public function getWikiID() {
 660                 return $this->getDomainID();
 661         }
 662
 663         /**
 664          * Get information about an index into an object
 665          * @param string $table Table name
 666          * @param string $index Index name
 667          * @param string $fname Calling function name
 668          * @return mixed Database-specific index description class or false if the index does not exist
 669          */
 670         abstract function indexInfo( $table, $index, $fname = __METHOD__ );
 671
 672         /**
 673          * Wrapper for addslashes()
 674          *
 675          * @param string $s String to be slashed.
 676          * @return string Slashed string.
 677          */
 678         abstract function strencode( $s );
 679
 680         /**
 681          * Set a custom error handler for logging errors during database connection
 682          */
 683         protected function installErrorHandler() {
 684                 $this->mPHPError = false;
 685                 $this->htmlErrors = ini_set( 'html_errors', '0' );
 686                 set_error_handler( [ $this, 'connectionErrorLogger' ] );
 687         }
 688
 689         /**
 690          * Restore the previous error handler and return the last PHP error for this DB
 691          *
 692          * @return bool|string
 693          */
 694         protected function restoreErrorHandler() {
 695                 restore_error_handler();
 696                 if ( $this->htmlErrors !== false ) {
 697                         ini_set( 'html_errors', $this->htmlErrors );
 698                 }
 699
 700                 return $this->getLastPHPError();
 701         }
 702
 703         /**
 704          * @return string|bool Last PHP error for this DB (typically connection errors)
 705          */
 706         protected function getLastPHPError() {
 707                 if ( $this->mPHPError ) {
 708                         $error = preg_replace( '!\[<a.*</a>\]!', '', $this->mPHPError );
 709                         $error = preg_replace( '!^.*?:\s?(.*)$!', '$1', $error );
 710
 711                         return $error;
 712                 }
 713
 714                 return false;
 715         }
 716
 717         /**
 718          * Error handler for logging errors during database connection
 719          * This method should not be used outside of Database classes
 720          *
 721          * @param int $errno
 722          * @param string $errstr
 723          */
 724         public function connectionErrorLogger( $errno, $errstr ) {
 725                 $this->mPHPError = $errstr;
 726         }
 727
 728         /**
 729          * Create a log context to pass to PSR-3 logger functions.
 730          *
 731          * @param array $extras Additional data to add to context
 732          * @return array
 733          */
 734         protected function getLogContext( array $extras = [] ) {
 735                 return array_merge(
 736                         [
 737                                 'db_server' => $this->mServer,
 738                                 'db_name' => $this->mDBname,
 739                                 'db_user' => $this->mUser,
 740                         ],
 741                         $extras
 742                 );
 743         }
 744
 745         public function close() {
 746                 if ( $this->mConn ) {
 747                         if ( $this->trxLevel() ) {
 748                                 $this->commit( __METHOD__, self::FLUSHING_INTERNAL );
 749                         }
 750
 751                         $closed = $this->closeConnection();
 752                         $this->mConn = false;
 753                 } elseif ( $this->mTrxIdleCallbacks || $this->mTrxEndCallbacks ) { // sanity
 754                         throw new RuntimeException( "Transaction callbacks still pending." );
 755                 } else {
 756                         $closed = true;
 757                 }
 758                 $this->mOpened = false;
 759
 760                 return $closed;
 761         }
 762
 763         /**
 764          * Make sure isOpen() returns true as a sanity check
 765          *
 766          * @throws DBUnexpectedError
 767          */
 768         protected function assertOpen() {
 769                 if ( !$this->isOpen() ) {
 770                         throw new DBUnexpectedError( $this, "DB connection was already closed." );
 771                 }
 772         }
 773
 774         /**
 775          * Closes underlying database connection
 776          * @since 1.20
 777          * @return bool Whether connection was closed successfully
 778          */
 779         abstract protected function closeConnection();
 780
 781         public function reportConnectionError( $error = 'Unknown error' ) {
 782                 $myError = $this->lastError();
 783                 if ( $myError ) {
 784                         $error = $myError;
 785                 }
 786
 787                 # New method
 788                 throw new DBConnectionError( $this, $error );
 789         }
 790
 791         /**
 792          * The DBMS-dependent part of query()
 793          *
 794          * @param string $sql SQL query.
 795          * @return ResultWrapper|bool Result object to feed to fetchObject,
 796          *   fetchRow, ...; or false on failure
 797          */
 798         abstract protected function doQuery( $sql );
 799
 800         /**
 801          * Determine whether a query writes to the DB.
 802          * Should return true if unsure.
 803          *
 804          * @param string $sql
 805          * @return bool
 806          */
 807         protected function isWriteQuery( $sql ) {
 808                 return !preg_match(
 809                         '/^(?:SELECT|BEGIN|ROLLBACK|COMMIT|SET|SHOW|EXPLAIN|\(SELECT)\b/i', $sql );
 810         }
 811
 812         /**
 813          * @param $sql
 814          * @return string|null
 815          */
 816         protected function getQueryVerb( $sql ) {
 817                 return preg_match( '/^\s*([a-z]+)/i', $sql, $m ) ? strtoupper( $m[1] ) : null;
 818         }
 819
 820         /**
 821          * Determine whether a SQL statement is sensitive to isolation level.
 822          * A SQL statement is considered transactable if its result could vary
 823          * depending on the transaction isolation level. Operational commands
 824          * such as 'SET' and 'SHOW' are not considered to be transactable.
 825          *
 826          * @param string $sql
 827          * @return bool
 828          */
 829         protected function isTransactableQuery( $sql ) {
 830                 return !in_array(
 831                         $this->getQueryVerb( $sql ),
 832                         [ 'BEGIN', 'COMMIT', 'ROLLBACK', 'SHOW', 'SET', 'CREATE', 'ALTER' ],
 833                         true
 834                 );
 835         }
 836
 837         /**
 838          * @param string $sql A SQL query
 839          * @return bool Whether $sql is SQL for TEMPORARY table operation
 840          */
 841         protected function registerTempTableOperation( $sql ) {
 842                 if ( preg_match(
 843                         '/^CREATE\s+TEMPORARY\s+TABLE\s+(?:IF\s+NOT\s+EXISTS\s+)?[`"\']?(\w+)[`"\']?/i',
 844                         $sql,
 845                         $matches
 846                 ) ) {
 847                         $this->mSessionTempTables[$matches[1]] = 1;
 848
 849                         return true;
 850                 } elseif ( preg_match(
 851                         '/^DROP\s+(?:TEMPORARY\s+)?TABLE\s+(?:IF\s+EXISTS\s+)?[`"\']?(\w+)[`"\']?/i',
 852                         $sql,
 853                         $matches
 854                 ) ) {
 855                         $isTemp = isset( $this->mSessionTempTables[$matches[1]] );
 856                         unset( $this->mSessionTempTables[$matches[1]] );
 857
 858                         return $isTemp;
 859                 } elseif ( preg_match(
 860                         '/^TRUNCATE\s+(?:TEMPORARY\s+)?TABLE\s+(?:IF\s+EXISTS\s+)?[`"\']?(\w+)[`"\']?/i',
 861                         $sql,
 862                         $matches
 863                 ) ) {
 864                         return isset( $this->mSessionTempTables[$matches[1]] );
 865                 } elseif ( preg_match(
 866                         '/^(?:INSERT\s+(?:\w+\s+)?INTO|UPDATE|DELETE\s+FROM)\s+[`"\']?(\w+)[`"\']?/i',
 867                         $sql,
 868                         $matches
 869                 ) ) {
 870                         return isset( $this->mSessionTempTables[$matches[1]] );
 871                 }
 872
 873                 return false;
 874         }
 875
 876         public function query( $sql, $fname = __METHOD__, $tempIgnore = false ) {
 877                 $priorWritesPending = $this->writesOrCallbacksPending();
 878                 $this->mLastQuery = $sql;
 879
 880                 $isWrite = $this->isWriteQuery( $sql );
 881                 if ( $isWrite ) {
 882                         $isNonTempWrite = !$this->registerTempTableOperation( $sql );
 883                 } else {
 884                         $isNonTempWrite = false;
 885                 }
 886
 887                 if ( $isWrite ) {
 888                         # In theory, non-persistent writes are allowed in read-only mode, but due to things
 889                         # like https://bugs.mysql.com/bug.php?id=33669 that might not work anyway...
 890                         $reason = $this->getReadOnlyReason();
 891                         if ( $reason !== false ) {
 892                                 throw new DBReadOnlyError( $this, "Database is read-only: $reason" );
 893                         }
 894                         # Set a flag indicating that writes have been done
 895                         $this->mLastWriteTime = microtime( true );
 896                 }
 897
 898                 # Add trace comment to the begin of the sql string, right after the operator.
 899                 # Or, for one-word queries (like "BEGIN" or COMMIT") add it to the end (T44598)
 900                 $commentedSql = preg_replace( '/\s|$/', " /* $fname {$this->agent} */ ", $sql, 1 );
 901
 902                 # Start implicit transactions that wrap the request if DBO_TRX is enabled
 903                 if ( !$this->mTrxLevel && $this->getFlag( self::DBO_TRX )
 904                         && $this->isTransactableQuery( $sql )
 905                 ) {
 906                         $this->begin( __METHOD__ . " ($fname)", self::TRANSACTION_INTERNAL );
 907                         $this->mTrxAutomatic = true;
 908                 }
 909
 910                 # Keep track of whether the transaction has write queries pending
 911                 if ( $this->mTrxLevel && !$this->mTrxDoneWrites && $isWrite ) {
 912                         $this->mTrxDoneWrites = true;
 913                         $this->trxProfiler->transactionWritingIn(
 914                                 $this->mServer, $this->mDBname, $this->mTrxShortId );
 915                 }
 916
 917                 if ( $this->getFlag( self::DBO_DEBUG ) ) {
 918                         $this->queryLogger->debug( "{$this->mDBname} {$commentedSql}" );
 919                 }
 920
 921                 # Avoid fatals if close() was called
 922                 $this->assertOpen();
 923
 924                 # Send the query to the server
 925                 $ret = $this->doProfiledQuery( $sql, $commentedSql, $isNonTempWrite, $fname );
 926
 927                 # Try reconnecting if the connection was lost
 928                 if ( false === $ret && $this->wasErrorReissuable() ) {
 929                         $recoverable = $this->canRecoverFromDisconnect( $sql, $priorWritesPending );
 930                         # Stash the last error values before anything might clear them
 931                         $lastError = $this->lastError();
 932                         $lastErrno = $this->lastErrno();
 933                         # Update state tracking to reflect transaction loss due to disconnection
 934                         $this->handleSessionLoss();
 935                         if ( $this->reconnect() ) {
 936                                 $msg = __METHOD__ . ": lost connection to {$this->getServer()}; reconnected";
 937                                 $this->connLogger->warning( $msg );
 938                                 $this->queryLogger->warning(
 939                                         "$msg:\n" . ( new RuntimeException() )->getTraceAsString() );
 940
 941                                 if ( !$recoverable ) {
 942                                         # Callers may catch the exception and continue to use the DB
 943                                         $this->reportQueryError( $lastError, $lastErrno, $sql, $fname );
 944                                 } else {
 945                                         # Should be safe to silently retry the query
 946                                         $ret = $this->doProfiledQuery( $sql, $commentedSql, $isNonTempWrite, $fname );
 947                                 }
 948                         } else {
 949                                 $msg = __METHOD__ . ": lost connection to {$this->getServer()} permanently";
 950                                 $this->connLogger->error( $msg );
 951                         }
 952                 }
 953
 954                 if ( false === $ret ) {
 955                         # Deadlocks cause the entire transaction to abort, not just the statement.
 956                         # https://dev.mysql.com/doc/refman/5.7/en/innodb-error-handling.html
 957                         # https://www.postgresql.org/docs/9.1/static/explicit-locking.html
 958                         if ( $this->wasDeadlock() ) {
 959                                 if ( $this->explicitTrxActive() || $priorWritesPending ) {
 960                                         $tempIgnore = false; // not recoverable
 961                                 }
 962                                 # Update state tracking to reflect transaction loss
 963                                 $this->handleSessionLoss();
 964                         }
 965
 966                         $this->reportQueryError(
 967                                 $this->lastError(), $this->lastErrno(), $sql, $fname, $tempIgnore );
 968                 }
 969
 970                 $res = $this->resultObject( $ret );
 971
 972                 return $res;
 973         }
 974
 975         /**
 976          * Helper method for query() that handles profiling and logging and sends
 977          * the query to doQuery()
 978          *
 979          * @param string $sql Original SQL query
 980          * @param string $commentedSql SQL query with debugging/trace comment
 981          * @param bool $isWrite Whether the query is a (non-temporary) write operation
 982          * @param string $fname Name of the calling function
 983          * @return bool|ResultWrapper True for a successful write query, ResultWrapper
 984          *     object for a successful read query, or false on failure
 985          */
 986         private function doProfiledQuery( $sql, $commentedSql, $isWrite, $fname ) {
 987                 $isMaster = !is_null( $this->getLBInfo( 'master' ) );
 988                 # generalizeSQL() will probably cut down the query to reasonable
 989                 # logging size most of the time. The substr is really just a sanity check.
 990                 if ( $isMaster ) {
 991                         $queryProf = 'query-m: ' . substr( self::generalizeSQL( $sql ), 0, 255 );
 992                 } else {
 993                         $queryProf = 'query: ' . substr( self::generalizeSQL( $sql ), 0, 255 );
 994                 }
 995
 996                 # Include query transaction state
 997                 $queryProf .= $this->mTrxShortId ? " [TRX#{$this->mTrxShortId}]" : "";
 998
 999                 $startTime = microtime( true );
1000                 if ( $this->profiler ) {
1001                         call_user_func( [ $this->profiler, 'profileIn' ], $queryProf );
1002                 }
1003                 $ret = $this->doQuery( $commentedSql );
1004                 if ( $this->profiler ) {
1005                         call_user_func( [ $this->profiler, 'profileOut' ], $queryProf );
1006                 }
1007                 $queryRuntime = max( microtime( true ) - $startTime, 0.0 );
1008
1009                 unset( $queryProfSection ); // profile out (if set)
1010
1011                 if ( $ret !== false ) {
1012                         $this->lastPing = $startTime;
1013                         if ( $isWrite && $this->mTrxLevel ) {
1014                                 $this->updateTrxWriteQueryTime( $sql, $queryRuntime );
1015                                 $this->mTrxWriteCallers[] = $fname;
1016                         }
1017                 }
1018
1019                 if ( $sql === self::PING_QUERY ) {
1020                         $this->mRTTEstimate = $queryRuntime;
1021                 }
1022
1023                 $this->trxProfiler->recordQueryCompletion(
1024                         $queryProf, $startTime, $isWrite, $this->affectedRows()
1025                 );
1026                 $this->queryLogger->debug( $sql, [
1027                         'method' => $fname,
1028                         'master' => $isMaster,
1029                         'runtime' => $queryRuntime,
1030                 ] );
1031
1032                 return $ret;
1033         }
1034
1035         /**
1036          * Update the estimated run-time of a query, not counting large row lock times
1037          *
1038          * LoadBalancer can be set to rollback transactions that will create huge replication
1039          * lag. It bases this estimate off of pendingWriteQueryDuration(). Certain simple
1040          * queries, like inserting a row can take a long time due to row locking. This method
1041          * uses some simple heuristics to discount those cases.
1042          *
1043          * @param string $sql A SQL write query
1044          * @param float $runtime Total runtime, including RTT
1045          */
1046         private function updateTrxWriteQueryTime( $sql, $runtime ) {
1047                 // Whether this is indicative of replica DB runtime (except for RBR or ws_repl)
1048                 $indicativeOfReplicaRuntime = true;
1049                 if ( $runtime > self::SLOW_WRITE_SEC ) {
1050                         $verb = $this->getQueryVerb( $sql );
1051                         // insert(), upsert(), replace() are fast unless bulky in size or blocked on locks
1052                         if ( $verb === 'INSERT' ) {
1053                                 $indicativeOfReplicaRuntime = $this->affectedRows() > self::SMALL_WRITE_ROWS;
1054                         } elseif ( $verb === 'REPLACE' ) {
1055                                 $indicativeOfReplicaRuntime = $this->affectedRows() > self::SMALL_WRITE_ROWS / 2;
1056                         }
1057                 }
1058
1059                 $this->mTrxWriteDuration += $runtime;
1060                 $this->mTrxWriteQueryCount += 1;
1061                 if ( $indicativeOfReplicaRuntime ) {
1062                         $this->mTrxWriteAdjDuration += $runtime;
1063                         $this->mTrxWriteAdjQueryCount += 1;
1064                 }
1065         }
1066
1067         /**
1068          * Determine whether or not it is safe to retry queries after a database
1069          * connection is lost
1070          *
1071          * @param string $sql SQL query
1072          * @param bool $priorWritesPending Whether there is a transaction open with
1073          *     possible write queries or transaction pre-commit/idle callbacks
1074          *     waiting on it to finish.
1075          * @return bool True if it is safe to retry the query, false otherwise
1076          */
1077         private function canRecoverFromDisconnect( $sql, $priorWritesPending ) {
1078                 # Transaction dropped; this can mean lost writes, or REPEATABLE-READ snapshots.
1079                 # Dropped connections also mean that named locks are automatically released.
1080                 # Only allow error suppression in autocommit mode or when the lost transaction
1081                 # didn't matter anyway (aside from DBO_TRX snapshot loss).
1082                 if ( $this->mNamedLocksHeld ) {
1083                         return false; // possible critical section violation
1084                 } elseif ( $sql === 'COMMIT' ) {
1085                         return !$priorWritesPending; // nothing written anyway? (T127428)
1086                 } elseif ( $sql === 'ROLLBACK' ) {
1087                         return true; // transaction lost...which is also what was requested :)
1088                 } elseif ( $this->explicitTrxActive() ) {
1089                         return false; // don't drop atomocity
1090                 } elseif ( $priorWritesPending ) {
1091                         return false; // prior writes lost from implicit transaction
1092                 }
1093
1094                 return true;
1095         }
1096
1097         /**
1098          * Clean things up after transaction loss due to disconnection
1099          *
1100          * @return null|Exception
1101          */
1102         private function handleSessionLoss() {
1103                 $this->mTrxLevel = 0;
1104                 $this->mTrxIdleCallbacks = []; // T67263
1105                 $this->mTrxPreCommitCallbacks = []; // T67263
1106                 $this->mSessionTempTables = [];
1107                 $this->mNamedLocksHeld = [];
1108                 try {
1109                         // Handle callbacks in mTrxEndCallbacks
1110                         $this->runOnTransactionIdleCallbacks( self::TRIGGER_ROLLBACK );
1111                         $this->runTransactionListenerCallbacks( self::TRIGGER_ROLLBACK );
1112                         return null;
1113                 } catch ( Exception $e ) {
1114                         // Already logged; move on...
1115                         return $e;
1116                 }
1117         }
1118
1119         public function reportQueryError( $error, $errno, $sql, $fname, $tempIgnore = false ) {
1120                 if ( $this->ignoreErrors() || $tempIgnore ) {
1121                         $this->queryLogger->debug( "SQL ERROR (ignored): $error\n" );
1122                 } else {
1123                         $sql1line = mb_substr( str_replace( "\n", "\\n", $sql ), 0, 5 * 1024 );
1124                         $this->queryLogger->error(
1125                                 "{fname}\t{db_server}\t{errno}\t{error}\t{sql1line}",
1126                                 $this->getLogContext( [
1127                                         'method' => __METHOD__,
1128                                         'errno' => $errno,
1129                                         'error' => $error,
1130                                         'sql1line' => $sql1line,
1131                                         'fname' => $fname,
1132                                 ] )
1133                         );
1134                         $this->queryLogger->debug( "SQL ERROR: " . $error . "\n" );
1135                         throw new DBQueryError( $this, $error, $errno, $sql, $fname );
1136                 }
1137         }
1138
1139         public function freeResult( $res ) {
1140         }
1141
1142         public function selectField(
1143                 $table, $var, $cond = '', $fname = __METHOD__, $options = []
1144         ) {
1145                 if ( $var === '*' ) { // sanity
1146                         throw new DBUnexpectedError( $this, "Cannot use a * field: got '$var'" );
1147                 }
1148
1149                 if ( !is_array( $options ) ) {
1150                         $options = [ $options ];
1151                 }
1152
1153                 $options['LIMIT'] = 1;
1154
1155                 $res = $this->select( $table, $var, $cond, $fname, $options );
1156                 if ( $res === false || !$this->numRows( $res ) ) {
1157                         return false;
1158                 }
1159
1160                 $row = $this->fetchRow( $res );
1161
1162                 if ( $row !== false ) {
1163                         return reset( $row );
1164                 } else {
1165                         return false;
1166                 }
1167         }
1168
1169         public function selectFieldValues(
1170                 $table, $var, $cond = '', $fname = __METHOD__, $options = [], $join_conds = []
1171         ) {
1172                 if ( $var === '*' ) { // sanity
1173                         throw new DBUnexpectedError( $this, "Cannot use a * field" );
1174                 } elseif ( !is_string( $var ) ) { // sanity
1175                         throw new DBUnexpectedError( $this, "Cannot use an array of fields" );
1176                 }
1177
1178                 if ( !is_array( $options ) ) {
1179                         $options = [ $options ];
1180                 }
1181
1182                 $res = $this->select( $table, $var, $cond, $fname, $options, $join_conds );
1183                 if ( $res === false ) {
1184                         return false;
1185                 }
1186
1187                 $values = [];
1188                 foreach ( $res as $row ) {
1189                         $values[] = $row->$var;
1190                 }
1191
1192                 return $values;
1193         }
1194
1195         /**
1196          * Returns an optional USE INDEX clause to go after the table, and a
1197          * string to go at the end of the query.
1198          *
1199          * @param array $options Associative array of options to be turned into
1200          *   an SQL query, valid keys are listed in the function.
1201          * @return array
1202          * @see Database::select()
1203          */
1204         protected function makeSelectOptions( $options ) {
1205                 $preLimitTail = $postLimitTail = '';
1206                 $startOpts = '';
1207
1208                 $noKeyOptions = [];
1209
1210                 foreach ( $options as $key => $option ) {
1211                         if ( is_numeric( $key ) ) {
1212                                 $noKeyOptions[$option] = true;
1213                         }
1214                 }
1215
1216                 $preLimitTail .= $this->makeGroupByWithHaving( $options );
1217
1218                 $preLimitTail .= $this->makeOrderBy( $options );
1219
1220                 if ( isset( $noKeyOptions['FOR UPDATE'] ) ) {
1221                         $postLimitTail .= ' FOR UPDATE';
1222                 }
1223
1224                 if ( isset( $noKeyOptions['LOCK IN SHARE MODE'] ) ) {
1225                         $postLimitTail .= ' LOCK IN SHARE MODE';
1226                 }
1227
1228                 if ( isset( $noKeyOptions['DISTINCT'] ) || isset( $noKeyOptions['DISTINCTROW'] ) ) {
1229                         $startOpts .= 'DISTINCT';
1230                 }
1231
1232                 # Various MySQL extensions
1233                 if ( isset( $noKeyOptions['STRAIGHT_JOIN'] ) ) {
1234                         $startOpts .= ' /*! STRAIGHT_JOIN */';
1235                 }
1236
1237                 if ( isset( $noKeyOptions['HIGH_PRIORITY'] ) ) {
1238                         $startOpts .= ' HIGH_PRIORITY';
1239                 }
1240
1241                 if ( isset( $noKeyOptions['SQL_BIG_RESULT'] ) ) {
1242                         $startOpts .= ' SQL_BIG_RESULT';
1243                 }
1244
1245                 if ( isset( $noKeyOptions['SQL_BUFFER_RESULT'] ) ) {
1246                         $startOpts .= ' SQL_BUFFER_RESULT';
1247                 }
1248
1249                 if ( isset( $noKeyOptions['SQL_SMALL_RESULT'] ) ) {
1250                         $startOpts .= ' SQL_SMALL_RESULT';
1251                 }
1252
1253                 if ( isset( $noKeyOptions['SQL_CALC_FOUND_ROWS'] ) ) {
1254                         $startOpts .= ' SQL_CALC_FOUND_ROWS';
1255                 }
1256
1257                 if ( isset( $noKeyOptions['SQL_CACHE'] ) ) {
1258                         $startOpts .= ' SQL_CACHE';
1259                 }
1260
1261                 if ( isset( $noKeyOptions['SQL_NO_CACHE'] ) ) {
1262                         $startOpts .= ' SQL_NO_CACHE';
1263                 }
1264
1265                 if ( isset( $options['USE INDEX'] ) && is_string( $options['USE INDEX'] ) ) {
1266                         $useIndex = $this->useIndexClause( $options['USE INDEX'] );
1267                 } else {
1268                         $useIndex = '';
1269                 }
1270                 if ( isset( $options['IGNORE INDEX'] ) && is_string( $options['IGNORE INDEX'] ) ) {
1271                         $ignoreIndex = $this->ignoreIndexClause( $options['IGNORE INDEX'] );
1272                 } else {
1273                         $ignoreIndex = '';
1274                 }
1275
1276                 return [ $startOpts, $useIndex, $preLimitTail, $postLimitTail, $ignoreIndex ];
1277         }
1278
1279         /**
1280          * Returns an optional GROUP BY with an optional HAVING
1281          *
1282          * @param array $options Associative array of options
1283          * @return string
1284          * @see Database::select()
1285          * @since 1.21
1286          */
1287         protected function makeGroupByWithHaving( $options ) {
1288                 $sql = '';
1289                 if ( isset( $options['GROUP BY'] ) ) {
1290                         $gb = is_array( $options['GROUP BY'] )
1291                                 ? implode( ',', $options['GROUP BY'] )
1292                                 : $options['GROUP BY'];
1293                         $sql .= ' GROUP BY ' . $gb;
1294                 }
1295                 if ( isset( $options['HAVING'] ) ) {
1296                         $having = is_array( $options['HAVING'] )
1297                                 ? $this->makeList( $options['HAVING'], self::LIST_AND )
1298                                 : $options['HAVING'];
1299                         $sql .= ' HAVING ' . $having;
1300                 }
1301
1302                 return $sql;
1303         }
1304
1305         /**
1306          * Returns an optional ORDER BY
1307          *
1308          * @param array $options Associative array of options
1309          * @return string
1310          * @see Database::select()
1311          * @since 1.21
1312          */
1313         protected function makeOrderBy( $options ) {
1314                 if ( isset( $options['ORDER BY'] ) ) {
1315                         $ob = is_array( $options['ORDER BY'] )
1316                                 ? implode( ',', $options['ORDER BY'] )
1317                                 : $options['ORDER BY'];
1318
1319                         return ' ORDER BY ' . $ob;
1320                 }
1321
1322                 return '';
1323         }
1324
1325         public function select( $table, $vars, $conds = '', $fname = __METHOD__,
1326                 $options = [], $join_conds = [] ) {
1327                 $sql = $this->selectSQLText( $table, $vars, $conds, $fname, $options, $join_conds );
1328
1329                 return $this->query( $sql, $fname );
1330         }
1331
1332         public function selectSQLText( $table, $vars, $conds = '', $fname = __METHOD__,
1333                 $options = [], $join_conds = []
1334         ) {
1335                 if ( is_array( $vars ) ) {
1336                         $vars = implode( ',', $this->fieldNamesWithAlias( $vars ) );
1337                 }
1338
1339                 $options = (array)$options;
1340                 $useIndexes = ( isset( $options['USE INDEX'] ) && is_array( $options['USE INDEX'] ) )
1341                         ? $options['USE INDEX']
1342                         : [];
1343                 $ignoreIndexes = (
1344                         isset( $options['IGNORE INDEX'] ) &&
1345                         is_array( $options['IGNORE INDEX'] )
1346                 )
1347                         ? $options['IGNORE INDEX']
1348                         : [];
1349
1350                 if ( is_array( $table ) ) {
1351                         $from = ' FROM ' .
1352                                 $this->tableNamesWithIndexClauseOrJOIN(
1353                                         $table, $useIndexes, $ignoreIndexes, $join_conds );
1354                 } elseif ( $table != '' ) {
1355                         if ( $table[0] == ' ' ) {
1356                                 $from = ' FROM ' . $table;
1357                         } else {
1358                                 $from = ' FROM ' .
1359                                         $this->tableNamesWithIndexClauseOrJOIN(
1360                                                 [ $table ], $useIndexes, $ignoreIndexes, [] );
1361                         }
1362                 } else {
1363                         $from = '';
1364                 }
1365
1366                 list( $startOpts, $useIndex, $preLimitTail, $postLimitTail, $ignoreIndex ) =
1367                         $this->makeSelectOptions( $options );
1368
1369                 if ( !empty( $conds ) ) {
1370                         if ( is_array( $conds ) ) {
1371                                 $conds = $this->makeList( $conds, self::LIST_AND );
1372                         }
1373                         $sql = "SELECT $startOpts $vars $from $useIndex $ignoreIndex " .
1374                                 "WHERE $conds $preLimitTail";
1375                 } else {
1376                         $sql = "SELECT $startOpts $vars $from $useIndex $ignoreIndex $preLimitTail";
1377                 }
1378
1379                 if ( isset( $options['LIMIT'] ) ) {
1380                         $sql = $this->limitResult( $sql, $options['LIMIT'],
1381                                 isset( $options['OFFSET'] ) ? $options['OFFSET'] : false );
1382                 }
1383                 $sql = "$sql $postLimitTail";
1384
1385                 if ( isset( $options['EXPLAIN'] ) ) {
1386                         $sql = 'EXPLAIN ' . $sql;
1387                 }
1388
1389                 return $sql;
1390         }
1391
1392         public function selectRow( $table, $vars, $conds, $fname = __METHOD__,
1393                 $options = [], $join_conds = []
1394         ) {
1395                 $options = (array)$options;
1396                 $options['LIMIT'] = 1;
1397                 $res = $this->select( $table, $vars, $conds, $fname, $options, $join_conds );
1398
1399                 if ( $res === false ) {
1400                         return false;
1401                 }
1402
1403                 if ( !$this->numRows( $res ) ) {
1404                         return false;
1405                 }
1406
1407                 $obj = $this->fetchObject( $res );
1408
1409                 return $obj;
1410         }
1411
1412         public function estimateRowCount(
1413                 $table, $vars = '*', $conds = '', $fname = __METHOD__, $options = []
1414         ) {
1415                 $rows = 0;
1416                 $res = $this->select( $table, [ 'rowcount' => 'COUNT(*)' ], $conds, $fname, $options );
1417
1418                 if ( $res ) {
1419                         $row = $this->fetchRow( $res );
1420                         $rows = ( isset( $row['rowcount'] ) ) ? (int)$row['rowcount'] : 0;
1421                 }
1422
1423                 return $rows;
1424         }
1425
1426         public function selectRowCount(
1427                 $tables, $vars = '*', $conds = '', $fname = __METHOD__, $options = [], $join_conds = []
1428         ) {
1429                 $rows = 0;
1430                 $sql = $this->selectSQLText( $tables, '1', $conds, $fname, $options, $join_conds );
1431                 // The identifier quotes is primarily for MSSQL.
1432                 $rowCountCol = $this->addIdentifierQuotes( "rowcount" );
1433                 $tableName = $this->addIdentifierQuotes( "tmp_count" );
1434                 $res = $this->query( "SELECT COUNT(*) AS $rowCountCol FROM ($sql) $tableName", $fname );
1435
1436                 if ( $res ) {
1437                         $row = $this->fetchRow( $res );
1438                         $rows = ( isset( $row['rowcount'] ) ) ? (int)$row['rowcount'] : 0;
1439                 }
1440
1441                 return $rows;
1442         }
1443
1444         /**
1445          * Removes most variables from an SQL query and replaces them with X or N for numbers.
1446          * It's only slightly flawed. Don't use for anything important.
1447          *
1448          * @param string $sql A SQL Query
1449          *
1450          * @return string
1451          */
1452         protected static function generalizeSQL( $sql ) {
1453                 # This does the same as the regexp below would do, but in such a way
1454                 # as to avoid crashing php on some large strings.
1455                 # $sql = preg_replace( "/'([^\\\\']|\\\\.)*'|\"([^\\\\\"]|\\\\.)*\"/", "'X'", $sql );
1456
1457                 $sql = str_replace( "\\\\", '', $sql );
1458                 $sql = str_replace( "\\'", '', $sql );
1459                 $sql = str_replace( "\\\"", '', $sql );
1460                 $sql = preg_replace( "/'.*'/s", "'X'", $sql );
1461                 $sql = preg_replace( '/".*"/s', "'X'", $sql );
1462
1463                 # All newlines, tabs, etc replaced by single space
1464                 $sql = preg_replace( '/\s+/', ' ', $sql );
1465
1466                 # All numbers => N,
1467                 # except the ones surrounded by characters, e.g. l10n
1468                 $sql = preg_replace( '/-?\d+(,-?\d+)+/s', 'N,...,N', $sql );
1469                 $sql = preg_replace( '/(?<![a-zA-Z])-?\d+(?![a-zA-Z])/s', 'N', $sql );
1470
1471                 return $sql;
1472         }
1473
1474         public function fieldExists( $table, $field, $fname = __METHOD__ ) {
1475                 $info = $this->fieldInfo( $table, $field );
1476
1477                 return (bool)$info;
1478         }
1479
1480         public function indexExists( $table, $index, $fname = __METHOD__ ) {
1481                 if ( !$this->tableExists( $table ) ) {
1482                         return null;
1483                 }
1484
1485                 $info = $this->indexInfo( $table, $index, $fname );
1486                 if ( is_null( $info ) ) {
1487                         return null;
1488                 } else {
1489                         return $info !== false;
1490                 }
1491         }
1492
1493         public function tableExists( $table, $fname = __METHOD__ ) {
1494                 $tableRaw = $this->tableName( $table, 'raw' );
1495                 if ( isset( $this->mSessionTempTables[$tableRaw] ) ) {
1496                         return true; // already known to exist
1497                 }
1498
1499                 $table = $this->tableName( $table );
1500                 $ignoreErrors = true;
1501                 $res = $this->query( "SELECT 1 FROM $table LIMIT 1", $fname, $ignoreErrors );
1502
1503                 return (bool)$res;
1504         }
1505
1506         public function indexUnique( $table, $index ) {
1507                 $indexInfo = $this->indexInfo( $table, $index );
1508
1509                 if ( !$indexInfo ) {
1510                         return null;
1511                 }
1512
1513                 return !$indexInfo[0]->Non_unique;
1514         }
1515
1516         /**
1517          * Helper for Database::insert().
1518          *
1519          * @param array $options
1520          * @return string
1521          */
1522         protected function makeInsertOptions( $options ) {
1523                 return implode( ' ', $options );
1524         }
1525
1526         public function insert( $table, $a, $fname = __METHOD__, $options = [] ) {
1527                 # No rows to insert, easy just return now
1528                 if ( !count( $a ) ) {
1529                         return true;
1530                 }
1531
1532                 $table = $this->tableName( $table );
1533
1534                 if ( !is_array( $options ) ) {
1535                         $options = [ $options ];
1536                 }
1537
1538                 $fh = null;
1539                 if ( isset( $options['fileHandle'] ) ) {
1540                         $fh = $options['fileHandle'];
1541                 }
1542                 $options = $this->makeInsertOptions( $options );
1543
1544                 if ( isset( $a[0] ) && is_array( $a[0] ) ) {
1545                         $multi = true;
1546                         $keys = array_keys( $a[0] );
1547                 } else {
1548                         $multi = false;
1549                         $keys = array_keys( $a );
1550                 }
1551
1552                 $sql = 'INSERT ' . $options .
1553                         " INTO $table (" . implode( ',', $keys ) . ') VALUES ';
1554
1555                 if ( $multi ) {
1556                         $first = true;
1557                         foreach ( $a as $row ) {
1558                                 if ( $first ) {
1559                                         $first = false;
1560                                 } else {
1561                                         $sql .= ',';
1562                                 }
1563                                 $sql .= '(' . $this->makeList( $row ) . ')';
1564                         }
1565                 } else {
1566                         $sql .= '(' . $this->makeList( $a ) . ')';
1567                 }
1568
1569                 if ( $fh !== null && false === fwrite( $fh, $sql ) ) {
1570                         return false;
1571                 } elseif ( $fh !== null ) {
1572                         return true;
1573                 }
1574
1575                 return (bool)$this->query( $sql, $fname );
1576         }
1577
1578         /**
1579          * Make UPDATE options array for Database::makeUpdateOptions
1580          *
1581          * @param array $options
1582          * @return array
1583          */
1584         protected function makeUpdateOptionsArray( $options ) {
1585                 if ( !is_array( $options ) ) {
1586                         $options = [ $options ];
1587                 }
1588
1589                 $opts = [];
1590
1591                 if ( in_array( 'IGNORE', $options ) ) {
1592                         $opts[] = 'IGNORE';
1593                 }
1594
1595                 return $opts;
1596         }
1597
1598         /**
1599          * Make UPDATE options for the Database::update function
1600          *
1601          * @param array $options The options passed to Database::update
1602          * @return string
1603          */
1604         protected function makeUpdateOptions( $options ) {
1605                 $opts = $this->makeUpdateOptionsArray( $options );
1606
1607                 return implode( ' ', $opts );
1608         }
1609
1610         public function update( $table, $values, $conds, $fname = __METHOD__, $options = [] ) {
1611                 $table = $this->tableName( $table );
1612                 $opts = $this->makeUpdateOptions( $options );
1613                 $sql = "UPDATE $opts $table SET " . $this->makeList( $values, self::LIST_SET );
1614
1615                 if ( $conds !== [] && $conds !== '*' ) {
1616                         $sql .= " WHERE " . $this->makeList( $conds, self::LIST_AND );
1617                 }
1618
1619                 return (bool)$this->query( $sql, $fname );
1620         }
1621
1622         public function makeList( $a, $mode = self::LIST_COMMA ) {
1623                 if ( !is_array( $a ) ) {
1624                         throw new DBUnexpectedError( $this, __METHOD__ . ' called with incorrect parameters' );
1625                 }
1626
1627                 $first = true;
1628                 $list = '';
1629
1630                 foreach ( $a as $field => $value ) {
1631                         if ( !$first ) {
1632                                 if ( $mode == self::LIST_AND ) {
1633                                         $list .= ' AND ';
1634                                 } elseif ( $mode == self::LIST_OR ) {
1635                                         $list .= ' OR ';
1636                                 } else {
1637                                         $list .= ',';
1638                                 }
1639                         } else {
1640                                 $first = false;
1641                         }
1642
1643                         if ( ( $mode == self::LIST_AND || $mode == self::LIST_OR ) && is_numeric( $field ) ) {
1644                                 $list .= "($value)";
1645                         } elseif ( $mode == self::LIST_SET && is_numeric( $field ) ) {
1646                                 $list .= "$value";
1647                         } elseif (
1648                                 ( $mode == self::LIST_AND || $mode == self::LIST_OR ) && is_array( $value )
1649                         ) {
1650                                 // Remove null from array to be handled separately if found
1651                                 $includeNull = false;
1652                                 foreach ( array_keys( $value, null, true ) as $nullKey ) {
1653                                         $includeNull = true;
1654                                         unset( $value[$nullKey] );
1655                                 }
1656                                 if ( count( $value ) == 0 && !$includeNull ) {
1657                                         throw new InvalidArgumentException(
1658                                                 __METHOD__ . ": empty input for field $field" );
1659                                 } elseif ( count( $value ) == 0 ) {
1660                                         // only check if $field is null
1661                                         $list .= "$field IS NULL";
1662                                 } else {
1663                                         // IN clause contains at least one valid element
1664                                         if ( $includeNull ) {
1665                                                 // Group subconditions to ensure correct precedence
1666                                                 $list .= '(';
1667                                         }
1668                                         if ( count( $value ) == 1 ) {
1669                                                 // Special-case single values, as IN isn't terribly efficient
1670                                                 // Don't necessarily assume the single key is 0; we don't
1671                                                 // enforce linear numeric ordering on other arrays here.
1672                                                 $value = array_values( $value )[0];
1673                                                 $list .= $field . " = " . $this->addQuotes( $value );
1674                                         } else {
1675                                                 $list .= $field . " IN (" . $this->makeList( $value ) . ") ";
1676                                         }
1677                                         // if null present in array, append IS NULL
1678                                         if ( $includeNull ) {
1679                                                 $list .= " OR $field IS NULL)";
1680                                         }
1681                                 }
1682                         } elseif ( $value === null ) {
1683                                 if ( $mode == self::LIST_AND || $mode == self::LIST_OR ) {
1684                                         $list .= "$field IS ";
1685                                 } elseif ( $mode == self::LIST_SET ) {
1686                                         $list .= "$field = ";
1687                                 }
1688                                 $list .= 'NULL';
1689                         } else {
1690                                 if (
1691                                         $mode == self::LIST_AND || $mode == self::LIST_OR || $mode == self::LIST_SET
1692                                 ) {
1693                                         $list .= "$field = ";
1694                                 }
1695                                 $list .= $mode == self::LIST_NAMES ? $value : $this->addQuotes( $value );
1696                         }
1697                 }
1698
1699                 return $list;
1700         }
1701
1702         public function makeWhereFrom2d( $data, $baseKey, $subKey ) {
1703                 $conds = [];
1704
1705                 foreach ( $data as $base => $sub ) {
1706                         if ( count( $sub ) ) {
1707                                 $conds[] = $this->makeList(
1708                                         [ $baseKey => $base, $subKey => array_keys( $sub ) ],
1709                                         self::LIST_AND );
1710                         }
1711                 }
1712
1713                 if ( $conds ) {
1714                         return $this->makeList( $conds, self::LIST_OR );
1715                 } else {
1716                         // Nothing to search for...
1717                         return false;
1718                 }
1719         }
1720
1721         public function aggregateValue( $valuedata, $valuename = 'value' ) {
1722                 return $valuename;
1723         }
1724
1725         public function bitNot( $field ) {
1726                 return "(~$field)";
1727         }
1728
1729         public function bitAnd( $fieldLeft, $fieldRight ) {
1730                 return "($fieldLeft & $fieldRight)";
1731         }
1732
1733         public function bitOr( $fieldLeft, $fieldRight ) {
1734                 return "($fieldLeft | $fieldRight)";
1735         }
1736
1737         public function buildConcat( $stringList ) {
1738                 return 'CONCAT(' . implode( ',', $stringList ) . ')';
1739         }
1740
1741         public function buildGroupConcatField(
1742                 $delim, $table, $field, $conds = '', $join_conds = []
1743         ) {
1744                 $fld = "GROUP_CONCAT($field SEPARATOR " . $this->addQuotes( $delim ) . ')';
1745
1746                 return '(' . $this->selectSQLText( $table, $fld, $conds, null, [], $join_conds ) . ')';
1747         }
1748
1749         public function buildStringCast( $field ) {
1750                 return $field;
1751         }
1752
1753         public function databasesAreIndependent() {
1754                 return false;
1755         }
1756
1757         public function selectDB( $db ) {
1758                 # Stub. Shouldn't cause serious problems if it's not overridden, but
1759                 # if your database engine supports a concept similar to MySQL's
1760                 # databases you may as well.
1761                 $this->mDBname = $db;
1762
1763                 return true;
1764         }
1765
1766         public function getDBname() {
1767                 return $this->mDBname;
1768         }
1769
1770         public function getServer() {
1771                 return $this->mServer;
1772         }
1773
1774         public function tableName( $name, $format = 'quoted' ) {
1775                 # Skip the entire process when we have a string quoted on both ends.
1776                 # Note that we check the end so that we will still quote any use of
1777                 # use of `database`.table. But won't break things if someone wants
1778                 # to query a database table with a dot in the name.
1779                 if ( $this->isQuotedIdentifier( $name ) ) {
1780                         return $name;
1781                 }
1782
1783                 # Lets test for any bits of text that should never show up in a table
1784                 # name. Basically anything like JOIN or ON which are actually part of
1785                 # SQL queries, but may end up inside of the table value to combine
1786                 # sql. Such as how the API is doing.
1787                 # Note that we use a whitespace test rather than a \b test to avoid
1788                 # any remote case where a word like on may be inside of a table name
1789                 # surrounded by symbols which may be considered word breaks.
1790                 if ( preg_match( '/(^|\s)(DISTINCT|JOIN|ON|AS)(\s|$)/i', $name ) !== 0 ) {
1791                         return $name;
1792                 }
1793
1794                 # Split database and table into proper variables.
1795                 # We reverse the explode so that database.table and table both output
1796                 # the correct table.
1797                 $dbDetails = explode( '.', $name, 3 );
1798                 if ( count( $dbDetails ) == 3 ) {
1799                         list( $database, $schema, $table ) = $dbDetails;
1800                         # We don't want any prefix added in this case
1801                         $prefix = '';
1802                 } elseif ( count( $dbDetails ) == 2 ) {
1803                         list( $database, $table ) = $dbDetails;
1804                         # We don't want any prefix added in this case
1805                         $prefix = '';
1806                         # In dbs that support it, $database may actually be the schema
1807                         # but that doesn't affect any of the functionality here
1808                         $schema = '';
1809                 } else {
1810                         list( $table ) = $dbDetails;
1811                         if ( isset( $this->tableAliases[$table] ) ) {
1812                                 $database = $this->tableAliases[$table]['dbname'];
1813                                 $schema = is_string( $this->tableAliases[$table]['schema'] )
1814                                         ? $this->tableAliases[$table]['schema']
1815                                         : $this->mSchema;
1816                                 $prefix = is_string( $this->tableAliases[$table]['prefix'] )
1817                                         ? $this->tableAliases[$table]['prefix']
1818                                         : $this->mTablePrefix;
1819                         } else {
1820                                 $database = '';
1821                                 $schema = $this->mSchema; # Default schema
1822                                 $prefix = $this->mTablePrefix; # Default prefix
1823                         }
1824                 }
1825
1826                 # Quote $table and apply the prefix if not quoted.
1827                 # $tableName might be empty if this is called from Database::replaceVars()
1828                 $tableName = "{$prefix}{$table}";
1829                 if ( $format === 'quoted'
1830                         && !$this->isQuotedIdentifier( $tableName )
1831                         && $tableName !== ''
1832                 ) {
1833                         $tableName = $this->addIdentifierQuotes( $tableName );
1834                 }
1835
1836                 # Quote $schema and $database and merge them with the table name if needed
1837                 $tableName = $this->prependDatabaseOrSchema( $schema, $tableName, $format );
1838                 $tableName = $this->prependDatabaseOrSchema( $database, $tableName, $format );
1839
1840                 return $tableName;
1841         }
1842
1843         /**
1844          * @param string|null $namespace Database or schema
1845          * @param string $relation Name of table, view, sequence, etc...
1846          * @param string $format One of (raw, quoted)
1847          * @return string Relation name with quoted and merged $namespace as needed
1848          */
1849         private function prependDatabaseOrSchema( $namespace, $relation, $format ) {
1850                 if ( strlen( $namespace ) ) {
1851                         if ( $format === 'quoted' && !$this->isQuotedIdentifier( $namespace ) ) {
1852                                 $namespace = $this->addIdentifierQuotes( $namespace );
1853                         }
1854                         $relation = $namespace . '.' . $relation;
1855                 }
1856
1857                 return $relation;
1858         }
1859
1860         public function tableNames() {
1861                 $inArray = func_get_args();
1862                 $retVal = [];
1863
1864                 foreach ( $inArray as $name ) {
1865                         $retVal[$name] = $this->tableName( $name );
1866                 }
1867
1868                 return $retVal;
1869         }
1870
1871         public function tableNamesN() {
1872                 $inArray = func_get_args();
1873                 $retVal = [];
1874
1875                 foreach ( $inArray as $name ) {
1876                         $retVal[] = $this->tableName( $name );
1877                 }
1878
1879                 return $retVal;
1880         }
1881
1882         /**
1883          * Get an aliased table name
1884          * e.g. tableName AS newTableName
1885          *
1886          * @param string $name Table name, see tableName()
1887          * @param string|bool $alias Alias (optional)
1888          * @return string SQL name for aliased table. Will not alias a table to its own name
1889          */
1890         protected function tableNameWithAlias( $name, $alias = false ) {
1891                 if ( !$alias || $alias == $name ) {
1892                         return $this->tableName( $name );
1893                 } else {
1894                         return $this->tableName( $name ) . ' ' . $this->addIdentifierQuotes( $alias );
1895                 }
1896         }
1897
1898         /**
1899          * Gets an array of aliased table names
1900          *
1901          * @param array $tables [ [alias] => table ]
1902          * @return string[] See tableNameWithAlias()
1903          */
1904         protected function tableNamesWithAlias( $tables ) {
1905                 $retval = [];
1906                 foreach ( $tables as $alias => $table ) {
1907                         if ( is_numeric( $alias ) ) {
1908                                 $alias = $table;
1909                         }
1910                         $retval[] = $this->tableNameWithAlias( $table, $alias );
1911                 }
1912
1913                 return $retval;
1914         }
1915
1916         /**
1917          * Get an aliased field name
1918          * e.g. fieldName AS newFieldName
1919          *
1920          * @param string $name Field name
1921          * @param string|bool $alias Alias (optional)
1922          * @return string SQL name for aliased field. Will not alias a field to its own name
1923          */
1924         protected function fieldNameWithAlias( $name, $alias = false ) {
1925                 if ( !$alias || (string)$alias === (string)$name ) {
1926                         return $name;
1927                 } else {
1928                         return $name . ' AS ' . $this->addIdentifierQuotes( $alias ); // PostgreSQL needs AS
1929                 }
1930         }
1931
1932         /**
1933          * Gets an array of aliased field names
1934          *
1935          * @param array $fields [ [alias] => field ]
1936          * @return string[] See fieldNameWithAlias()
1937          */
1938         protected function fieldNamesWithAlias( $fields ) {
1939                 $retval = [];
1940                 foreach ( $fields as $alias => $field ) {
1941                         if ( is_numeric( $alias ) ) {
1942                                 $alias = $field;
1943                         }
1944                         $retval[] = $this->fieldNameWithAlias( $field, $alias );
1945                 }
1946
1947                 return $retval;
1948         }
1949
1950         /**
1951          * Get the aliased table name clause for a FROM clause
1952          * which might have a JOIN and/or USE INDEX or IGNORE INDEX clause
1953          *
1954          * @param array $tables ( [alias] => table )
1955          * @param array $use_index Same as for select()
1956          * @param array $ignore_index Same as for select()
1957          * @param array $join_conds Same as for select()
1958          * @return string
1959          */
1960         protected function tableNamesWithIndexClauseOrJOIN(
1961                 $tables, $use_index = [], $ignore_index = [], $join_conds = []
1962         ) {
1963                 $ret = [];
1964                 $retJOIN = [];
1965                 $use_index = (array)$use_index;
1966                 $ignore_index = (array)$ignore_index;
1967                 $join_conds = (array)$join_conds;
1968
1969                 foreach ( $tables as $alias => $table ) {
1970                         if ( !is_string( $alias ) ) {
1971                                 // No alias? Set it equal to the table name
1972                                 $alias = $table;
1973                         }
1974                         // Is there a JOIN clause for this table?
1975                         if ( isset( $join_conds[$alias] ) ) {
1976                                 list( $joinType, $conds ) = $join_conds[$alias];
1977                                 $tableClause = $joinType;
1978                                 $tableClause .= ' ' . $this->tableNameWithAlias( $table, $alias );
1979                                 if ( isset( $use_index[$alias] ) ) { // has USE INDEX?
1980                                         $use = $this->useIndexClause( implode( ',', (array)$use_index[$alias] ) );
1981                                         if ( $use != '' ) {
1982                                                 $tableClause .= ' ' . $use;
1983                                         }
1984                                 }
1985                                 if ( isset( $ignore_index[$alias] ) ) { // has IGNORE INDEX?
1986                                         $ignore = $this->ignoreIndexClause(
1987                                                 implode( ',', (array)$ignore_index[$alias] ) );
1988                                         if ( $ignore != '' ) {
1989                                                 $tableClause .= ' ' . $ignore;
1990                                         }
1991                                 }
1992                                 $on = $this->makeList( (array)$conds, self::LIST_AND );
1993                                 if ( $on != '' ) {
1994                                         $tableClause .= ' ON (' . $on . ')';
1995                                 }
1996
1997                                 $retJOIN[] = $tableClause;
1998                         } elseif ( isset( $use_index[$alias] ) ) {
1999                                 // Is there an INDEX clause for this table?
2000                                 $tableClause = $this->tableNameWithAlias( $table, $alias );
2001                                 $tableClause .= ' ' . $this->useIndexClause(
2002                                                 implode( ',', (array)$use_index[$alias] )
2003                                         );
2004
2005                                 $ret[] = $tableClause;
2006                         } elseif ( isset( $ignore_index[$alias] ) ) {
2007                                 // Is there an INDEX clause for this table?
2008                                 $tableClause = $this->tableNameWithAlias( $table, $alias );
2009                                 $tableClause .= ' ' . $this->ignoreIndexClause(
2010                                                 implode( ',', (array)$ignore_index[$alias] )
2011                                         );
2012
2013                                 $ret[] = $tableClause;
2014                         } else {
2015                                 $tableClause = $this->tableNameWithAlias( $table, $alias );
2016
2017                                 $ret[] = $tableClause;
2018                         }
2019                 }
2020
2021                 // We can't separate explicit JOIN clauses with ',', use ' ' for those
2022                 $implicitJoins = !empty( $ret ) ? implode( ',', $ret ) : "";
2023                 $explicitJoins = !empty( $retJOIN ) ? implode( ' ', $retJOIN ) : "";
2024
2025                 // Compile our final table clause
2026                 return implode( ' ', [ $implicitJoins, $explicitJoins ] );
2027         }
2028
2029         /**
2030          * Allows for index remapping in queries where this is not consistent across DBMS
2031          *
2032          * @param string $index
2033          * @return string
2034          */
2035         protected function indexName( $index ) {
2036                 return $index;
2037         }
2038
2039         public function addQuotes( $s ) {
2040                 if ( $s instanceof Blob ) {
2041                         $s = $s->fetch();
2042                 }
2043                 if ( $s === null ) {
2044                         return 'NULL';
2045                 } elseif ( is_bool( $s ) ) {
2046                         return (int)$s;
2047                 } else {
2048                         # This will also quote numeric values. This should be harmless,
2049                         # and protects against weird problems that occur when they really
2050                         # _are_ strings such as article titles and string->number->string
2051                         # conversion is not 1:1.
2052                         return "'" . $this->strencode( $s ) . "'";
2053                 }
2054         }
2055
2056         /**
2057          * Quotes an identifier using `backticks` or "double quotes" depending on the database type.
2058          * MySQL uses `backticks` while basically everything else uses double quotes.
2059          * Since MySQL is the odd one out here the double quotes are our generic
2060          * and we implement backticks in DatabaseMysql.
2061          *
2062          * @param string $s
2063          * @return string
2064          */
2065         public function addIdentifierQuotes( $s ) {
2066                 return '"' . str_replace( '"', '""', $s ) . '"';
2067         }
2068
2069         /**
2070          * Returns if the given identifier looks quoted or not according to
2071          * the database convention for quoting identifiers .
2072          *
2073          * @note Do not use this to determine if untrusted input is safe.
2074          *   A malicious user can trick this function.
2075          * @param string $name
2076          * @return bool
2077          */
2078         public function isQuotedIdentifier( $name ) {
2079                 return $name[0] == '"' && substr( $name, -1, 1 ) == '"';
2080         }
2081
2082         /**
2083          * @param string $s
2084          * @return string
2085          */
2086         protected function escapeLikeInternal( $s, $escapeChar = '`' ) {
2087                 return str_replace( [ $escapeChar, '%', '_' ],
2088                         [ "{$escapeChar}{$escapeChar}", "{$escapeChar}%", "{$escapeChar}_" ],
2089                         $s );
2090         }
2091
2092         public function buildLike() {
2093                 $params = func_get_args();
2094
2095                 if ( count( $params ) > 0 && is_array( $params[0] ) ) {
2096                         $params = $params[0];
2097                 }
2098
2099                 $s = '';
2100
2101                 // We use ` instead of \ as the default LIKE escape character, since addQuotes()
2102                 // may escape backslashes, creating problems of double escaping. The `
2103                 // character has good cross-DBMS compatibility, avoiding special operators
2104                 // in MS SQL like ^ and %
2105                 $escapeChar = '`';
2106
2107                 foreach ( $params as $value ) {
2108                         if ( $value instanceof LikeMatch ) {
2109                                 $s .= $value->toString();
2110                         } else {
2111                                 $s .= $this->escapeLikeInternal( $value, $escapeChar );
2112                         }
2113                 }
2114
2115                 return ' LIKE ' . $this->addQuotes( $s ) . ' ESCAPE ' . $this->addQuotes( $escapeChar ) . ' ';
2116         }
2117
2118         public function anyChar() {
2119                 return new LikeMatch( '_' );
2120         }
2121
2122         public function anyString() {
2123                 return new LikeMatch( '%' );
2124         }
2125
2126         public function nextSequenceValue( $seqName ) {
2127                 return null;
2128         }
2129
2130         /**
2131          * USE INDEX clause. Unlikely to be useful for anything but MySQL. This
2132          * is only needed because a) MySQL must be as efficient as possible due to
2133          * its use on Wikipedia, and b) MySQL 4.0 is kind of dumb sometimes about
2134          * which index to pick. Anyway, other databases might have different
2135          * indexes on a given table. So don't bother overriding this unless you're
2136          * MySQL.
2137          * @param string $index
2138          * @return string
2139          */
2140         public function useIndexClause( $index ) {
2141                 return '';
2142         }
2143
2144         /**
2145          * IGNORE INDEX clause. Unlikely to be useful for anything but MySQL. This
2146          * is only needed because a) MySQL must be as efficient as possible due to
2147          * its use on Wikipedia, and b) MySQL 4.0 is kind of dumb sometimes about
2148          * which index to pick. Anyway, other databases might have different
2149          * indexes on a given table. So don't bother overriding this unless you're
2150          * MySQL.
2151          * @param string $index
2152          * @return string
2153          */
2154         public function ignoreIndexClause( $index ) {
2155                 return '';
2156         }
2157
2158         public function replace( $table, $uniqueIndexes, $rows, $fname = __METHOD__ ) {
2159                 $quotedTable = $this->tableName( $table );
2160
2161                 if ( count( $rows ) == 0 ) {
2162                         return;
2163                 }
2164
2165                 # Single row case
2166                 if ( !is_array( reset( $rows ) ) ) {
2167                         $rows = [ $rows ];
2168                 }
2169
2170                 // @FXIME: this is not atomic, but a trx would break affectedRows()
2171                 foreach ( $rows as $row ) {
2172                         # Delete rows which collide
2173                         if ( $uniqueIndexes ) {
2174                                 $sql = "DELETE FROM $quotedTable WHERE ";
2175                                 $first = true;
2176                                 foreach ( $uniqueIndexes as $index ) {
2177                                         if ( $first ) {
2178                                                 $first = false;
2179                                                 $sql .= '( ';
2180                                         } else {
2181                                                 $sql .= ' ) OR ( ';
2182                                         }
2183                                         if ( is_array( $index ) ) {
2184                                                 $first2 = true;
2185                                                 foreach ( $index as $col ) {
2186                                                         if ( $first2 ) {
2187                                                                 $first2 = false;
2188                                                         } else {
2189                                                                 $sql .= ' AND ';
2190                                                         }
2191                                                         $sql .= $col . '=' . $this->addQuotes( $row[$col] );
2192                                                 }
2193                                         } else {
2194                                                 $sql .= $index . '=' . $this->addQuotes( $row[$index] );
2195                                         }
2196                                 }
2197                                 $sql .= ' )';
2198                                 $this->query( $sql, $fname );
2199                         }
2200
2201                         # Now insert the row
2202                         $this->insert( $table, $row, $fname );
2203                 }
2204         }
2205
2206         /**
2207          * REPLACE query wrapper for MySQL and SQLite, which have a native REPLACE
2208          * statement.
2209          *
2210          * @param string $table Table name
2211          * @param array|string $rows Row(s) to insert
2212          * @param string $fname Caller function name
2213          *
2214          * @return ResultWrapper
2215          */
2216         protected function nativeReplace( $table, $rows, $fname ) {
2217                 $table = $this->tableName( $table );
2218
2219                 # Single row case
2220                 if ( !is_array( reset( $rows ) ) ) {
2221                         $rows = [ $rows ];
2222                 }
2223
2224                 $sql = "REPLACE INTO $table (" . implode( ',', array_keys( $rows[0] ) ) . ') VALUES ';
2225                 $first = true;
2226
2227                 foreach ( $rows as $row ) {
2228                         if ( $first ) {
2229                                 $first = false;
2230                         } else {
2231                                 $sql .= ',';
2232                         }
2233
2234                         $sql .= '(' . $this->makeList( $row ) . ')';
2235                 }
2236
2237                 return $this->query( $sql, $fname );
2238         }
2239
2240         public function upsert( $table, array $rows, array $uniqueIndexes, array $set,
2241                 $fname = __METHOD__
2242         ) {
2243                 if ( !count( $rows ) ) {
2244                         return true; // nothing to do
2245                 }
2246
2247                 if ( !is_array( reset( $rows ) ) ) {
2248                         $rows = [ $rows ];
2249                 }
2250
2251                 if ( count( $uniqueIndexes ) ) {
2252                         $clauses = []; // list WHERE clauses that each identify a single row
2253                         foreach ( $rows as $row ) {
2254                                 foreach ( $uniqueIndexes as $index ) {
2255                                         $index = is_array( $index ) ? $index : [ $index ]; // columns
2256                                         $rowKey = []; // unique key to this row
2257                                         foreach ( $index as $column ) {
2258                                                 $rowKey[$column] = $row[$column];
2259                                         }
2260                                         $clauses[] = $this->makeList( $rowKey, self::LIST_AND );
2261                                 }
2262                         }
2263                         $where = [ $this->makeList( $clauses, self::LIST_OR ) ];
2264                 } else {
2265                         $where = false;
2266                 }
2267
2268                 $useTrx = !$this->mTrxLevel;
2269                 if ( $useTrx ) {
2270                         $this->begin( $fname, self::TRANSACTION_INTERNAL );
2271                 }
2272                 try {
2273                         # Update any existing conflicting row(s)
2274                         if ( $where !== false ) {
2275                                 $ok = $this->update( $table, $set, $where, $fname );
2276                         } else {
2277                                 $ok = true;
2278                         }
2279                         # Now insert any non-conflicting row(s)
2280                         $ok = $this->insert( $table, $rows, $fname, [ 'IGNORE' ] ) && $ok;
2281                 } catch ( Exception $e ) {
2282                         if ( $useTrx ) {
2283                                 $this->rollback( $fname, self::FLUSHING_INTERNAL );
2284                         }
2285                         throw $e;
2286                 }
2287                 if ( $useTrx ) {
2288                         $this->commit( $fname, self::FLUSHING_INTERNAL );
2289                 }
2290
2291                 return $ok;
2292         }
2293
2294         public function deleteJoin( $delTable, $joinTable, $delVar, $joinVar, $conds,
2295                 $fname = __METHOD__
2296         ) {
2297                 if ( !$conds ) {
2298                         throw new DBUnexpectedError( $this, __METHOD__ . ' called with empty $conds' );
2299                 }
2300
2301                 $delTable = $this->tableName( $delTable );
2302                 $joinTable = $this->tableName( $joinTable );
2303                 $sql = "DELETE FROM $delTable WHERE $delVar IN (SELECT $joinVar FROM $joinTable ";
2304                 if ( $conds != '*' ) {
2305                         $sql .= 'WHERE ' . $this->makeList( $conds, self::LIST_AND );
2306                 }
2307                 $sql .= ')';
2308
2309                 $this->query( $sql, $fname );
2310         }
2311
2312         public function textFieldSize( $table, $field ) {
2313                 $table = $this->tableName( $table );
2314                 $sql = "SHOW COLUMNS FROM $table LIKE \"$field\";";
2315                 $res = $this->query( $sql, __METHOD__ );
2316                 $row = $this->fetchObject( $res );
2317
2318                 $m = [];
2319
2320                 if ( preg_match( '/\((.*)\)/', $row->Type, $m ) ) {
2321                         $size = $m[1];
2322                 } else {
2323                         $size = -1;
2324                 }
2325
2326                 return $size;
2327         }
2328
2329         public function delete( $table, $conds, $fname = __METHOD__ ) {
2330                 if ( !$conds ) {
2331                         throw new DBUnexpectedError( $this, __METHOD__ . ' called with no conditions' );
2332                 }
2333
2334                 $table = $this->tableName( $table );
2335                 $sql = "DELETE FROM $table";
2336
2337                 if ( $conds != '*' ) {
2338                         if ( is_array( $conds ) ) {
2339                                 $conds = $this->makeList( $conds, self::LIST_AND );
2340                         }
2341                         $sql .= ' WHERE ' . $conds;
2342                 }
2343
2344                 return $this->query( $sql, $fname );
2345         }
2346
2347         public function insertSelect(
2348                 $destTable, $srcTable, $varMap, $conds,
2349                 $fname = __METHOD__, $insertOptions = [], $selectOptions = []
2350         ) {
2351                 if ( $this->cliMode ) {
2352                         // For massive migrations with downtime, we don't want to select everything
2353                         // into memory and OOM, so do all this native on the server side if possible.
2354                         return $this->nativeInsertSelect(
2355                                 $destTable,
2356                                 $srcTable,
2357                                 $varMap,
2358                                 $conds,
2359                                 $fname,
2360                                 $insertOptions,
2361                                 $selectOptions
2362                         );
2363                 }
2364
2365                 // For web requests, do a locking SELECT and then INSERT. This puts the SELECT burden
2366                 // on only the master (without needing row-based-replication). It also makes it easy to
2367                 // know how big the INSERT is going to be.
2368                 $fields = [];
2369                 foreach ( $varMap as $dstColumn => $sourceColumnOrSql ) {
2370                         $fields[] = $this->fieldNameWithAlias( $sourceColumnOrSql, $dstColumn );
2371                 }
2372                 $selectOptions[] = 'FOR UPDATE';
2373                 $res = $this->select( $srcTable, implode( ',', $fields ), $conds, $fname, $selectOptions );
2374                 if ( !$res ) {
2375                         return false;
2376                 }
2377
2378                 $rows = [];
2379                 foreach ( $res as $row ) {
2380                         $rows[] = (array)$row;
2381                 }
2382
2383                 return $this->insert( $destTable, $rows, $fname, $insertOptions );
2384         }
2385
2386         /**
2387          * Native server-side implementation of insertSelect() for situations where
2388          * we don't want to select everything into memory
2389          *
2390          * @see IDatabase::insertSelect()
2391          */
2392         protected function nativeInsertSelect( $destTable, $srcTable, $varMap, $conds,
2393                 $fname = __METHOD__,
2394                 $insertOptions = [], $selectOptions = []
2395         ) {
2396                 $destTable = $this->tableName( $destTable );
2397
2398                 if ( !is_array( $insertOptions ) ) {
2399                         $insertOptions = [ $insertOptions ];
2400                 }
2401
2402                 $insertOptions = $this->makeInsertOptions( $insertOptions );
2403
2404                 if ( !is_array( $selectOptions ) ) {
2405                         $selectOptions = [ $selectOptions ];
2406                 }
2407
2408                 list( $startOpts, $useIndex, $tailOpts, $ignoreIndex ) = $this->makeSelectOptions(
2409                         $selectOptions );
2410
2411                 if ( is_array( $srcTable ) ) {
2412                         $srcTable = implode( ',', array_map( [ $this, 'tableName' ], $srcTable ) );
2413                 } else {
2414                         $srcTable = $this->tableName( $srcTable );
2415                 }
2416
2417                 $sql = "INSERT $insertOptions" .
2418                         " INTO $destTable (" . implode( ',', array_keys( $varMap ) ) . ')' .
2419                         " SELECT $startOpts " . implode( ',', $varMap ) .
2420                         " FROM $srcTable $useIndex $ignoreIndex ";
2421
2422                 if ( $conds != '*' ) {
2423                         if ( is_array( $conds ) ) {
2424                                 $conds = $this->makeList( $conds, self::LIST_AND );
2425                         }
2426                         $sql .= " WHERE $conds";
2427                 }
2428
2429                 $sql .= " $tailOpts";
2430
2431                 return $this->query( $sql, $fname );
2432         }
2433
2434         /**
2435          * Construct a LIMIT query with optional offset. This is used for query
2436          * pages. The SQL should be adjusted so that only the first $limit rows
2437          * are returned. If $offset is provided as well, then the first $offset
2438          * rows should be discarded, and the next $limit rows should be returned.
2439          * If the result of the query is not ordered, then the rows to be returned
2440          * are theoretically arbitrary.
2441          *
2442          * $sql is expected to be a SELECT, if that makes a difference.
2443          *
2444          * The version provided by default works in MySQL and SQLite. It will very
2445          * likely need to be overridden for most other DBMSes.
2446          *
2447          * @param string $sql SQL query we will append the limit too
2448          * @param int $limit The SQL limit
2449          * @param int|bool $offset The SQL offset (default false)
2450          * @throws DBUnexpectedError
2451          * @return string
2452          */
2453         public function limitResult( $sql, $limit, $offset = false ) {
2454                 if ( !is_numeric( $limit ) ) {
2455                         throw new DBUnexpectedError( $this,
2456                                 "Invalid non-numeric limit passed to limitResult()\n" );
2457                 }
2458
2459                 return "$sql LIMIT "
2460                 . ( ( is_numeric( $offset ) && $offset != 0 ) ? "{$offset}," : "" )
2461                 . "{$limit} ";
2462         }
2463
2464         public function unionSupportsOrderAndLimit() {
2465                 return true; // True for almost every DB supported
2466         }
2467
2468         public function unionQueries( $sqls, $all ) {
2469                 $glue = $all ? ') UNION ALL (' : ') UNION (';
2470
2471                 return '(' . implode( $glue, $sqls ) . ')';
2472         }
2473
2474         public function conditional( $cond, $trueVal, $falseVal ) {
2475                 if ( is_array( $cond ) ) {
2476                         $cond = $this->makeList( $cond, self::LIST_AND );
2477                 }
2478
2479                 return " (CASE WHEN $cond THEN $trueVal ELSE $falseVal END) ";
2480         }
2481
2482         public function strreplace( $orig, $old, $new ) {
2483                 return "REPLACE({$orig}, {$old}, {$new})";
2484         }
2485
2486         public function getServerUptime() {
2487                 return 0;
2488         }
2489
2490         public function wasDeadlock() {
2491                 return false;
2492         }
2493
2494         public function wasLockTimeout() {
2495                 return false;
2496         }
2497
2498         public function wasErrorReissuable() {
2499                 return false;
2500         }
2501
2502         public function wasReadOnlyError() {
2503                 return false;
2504         }
2505
2506         /**
2507          * Do not use this method outside of Database/DBError classes
2508          *
2509          * @param integer|string $errno
2510          * @return bool Whether the given query error was a connection drop
2511          */
2512         public function wasConnectionError( $errno ) {
2513                 return false;
2514         }
2515
2516         public function deadlockLoop() {
2517                 $args = func_get_args();
2518                 $function = array_shift( $args );
2519                 $tries = self::DEADLOCK_TRIES;
2520
2521                 $this->begin( __METHOD__ );
2522
2523                 $retVal = null;
2524                 /** @var Exception $e */
2525                 $e = null;
2526                 do {
2527                         try {
2528                                 $retVal = call_user_func_array( $function, $args );
2529                                 break;
2530                         } catch ( DBQueryError $e ) {
2531                                 if ( $this->wasDeadlock() ) {
2532                                         // Retry after a randomized delay
2533                                         usleep( mt_rand( self::DEADLOCK_DELAY_MIN, self::DEADLOCK_DELAY_MAX ) );
2534                                 } else {
2535                                         // Throw the error back up
2536                                         throw $e;
2537                                 }
2538                         }
2539                 } while ( --$tries > 0 );
2540
2541                 if ( $tries <= 0 ) {
2542                         // Too many deadlocks; give up
2543                         $this->rollback( __METHOD__ );
2544                         throw $e;
2545                 } else {
2546                         $this->commit( __METHOD__ );
2547
2548                         return $retVal;
2549                 }
2550         }
2551
2552         public function masterPosWait( DBMasterPos $pos, $timeout ) {
2553                 # Real waits are implemented in the subclass.
2554                 return 0;
2555         }
2556
2557         public function getReplicaPos() {
2558                 # Stub
2559                 return false;
2560         }
2561
2562         public function getMasterPos() {
2563                 # Stub
2564                 return false;
2565         }
2566
2567         public function serverIsReadOnly() {
2568                 return false;
2569         }
2570
2571         final public function onTransactionResolution( callable $callback, $fname = __METHOD__ ) {
2572                 if ( !$this->mTrxLevel ) {
2573                         throw new DBUnexpectedError( $this, "No transaction is active." );
2574                 }
2575                 $this->mTrxEndCallbacks[] = [ $callback, $fname ];
2576         }
2577
2578         final public function onTransactionIdle( callable $callback, $fname = __METHOD__ ) {
2579                 $this->mTrxIdleCallbacks[] = [ $callback, $fname ];
2580                 if ( !$this->mTrxLevel ) {
2581                         $this->runOnTransactionIdleCallbacks( self::TRIGGER_IDLE );
2582                 }
2583         }
2584
2585         final public function onTransactionPreCommitOrIdle( callable $callback, $fname = __METHOD__ ) {
2586                 if ( $this->mTrxLevel ) {
2587                         $this->mTrxPreCommitCallbacks[] = [ $callback, $fname ];
2588                 } else {
2589                         // If no transaction is active, then make one for this callback
2590                         $this->startAtomic( __METHOD__ );
2591                         try {
2592                                 call_user_func( $callback );
2593                                 $this->endAtomic( __METHOD__ );
2594                         } catch ( Exception $e ) {
2595                                 $this->rollback( __METHOD__, self::FLUSHING_INTERNAL );
2596                                 throw $e;
2597                         }
2598                 }
2599         }
2600
2601         final public function setTransactionListener( $name, callable $callback = null ) {
2602                 if ( $callback ) {
2603                         $this->mTrxRecurringCallbacks[$name] = $callback;
2604                 } else {
2605                         unset( $this->mTrxRecurringCallbacks[$name] );
2606                 }
2607         }
2608
2609         /**
2610          * Whether to disable running of post-COMMIT/ROLLBACK callbacks
2611          *
2612          * This method should not be used outside of Database/LoadBalancer
2613          *
2614          * @param bool $suppress
2615          * @since 1.28
2616          */
2617         final public function setTrxEndCallbackSuppression( $suppress ) {
2618                 $this->mTrxEndCallbacksSuppressed = $suppress;
2619         }
2620
2621         /**
2622          * Actually run and consume any "on transaction idle/resolution" callbacks.
2623          *
2624          * This method should not be used outside of Database/LoadBalancer
2625          *
2626          * @param integer $trigger IDatabase::TRIGGER_* constant
2627          * @since 1.20
2628          * @throws Exception
2629          */
2630         public function runOnTransactionIdleCallbacks( $trigger ) {
2631                 if ( $this->mTrxEndCallbacksSuppressed ) {
2632                         return;
2633                 }
2634
2635                 $autoTrx = $this->getFlag( self::DBO_TRX ); // automatic begin() enabled?
2636                 /** @var Exception $e */
2637                 $e = null; // first exception
2638                 do { // callbacks may add callbacks :)
2639                         $callbacks = array_merge(
2640                                 $this->mTrxIdleCallbacks,
2641                                 $this->mTrxEndCallbacks // include "transaction resolution" callbacks
2642                         );
2643                         $this->mTrxIdleCallbacks = []; // consumed (and recursion guard)
2644                         $this->mTrxEndCallbacks = []; // consumed (recursion guard)
2645                         foreach ( $callbacks as $callback ) {
2646                                 try {
2647                                         list( $phpCallback ) = $callback;
2648                                         $this->clearFlag( self::DBO_TRX ); // make each query its own transaction
2649                                         call_user_func_array( $phpCallback, [ $trigger ] );
2650                                         if ( $autoTrx ) {
2651                                                 $this->setFlag( self::DBO_TRX ); // restore automatic begin()
2652                                         } else {
2653                                                 $this->clearFlag( self::DBO_TRX ); // restore auto-commit
2654                                         }
2655                                 } catch ( Exception $ex ) {
2656                                         call_user_func( $this->errorLogger, $ex );
2657                                         $e = $e ?: $ex;
2658                                         // Some callbacks may use startAtomic/endAtomic, so make sure
2659                                         // their transactions are ended so other callbacks don't fail
2660                                         if ( $this->trxLevel() ) {
2661                                                 $this->rollback( __METHOD__, self::FLUSHING_INTERNAL );
2662                                         }
2663                                 }
2664                         }
2665                 } while ( count( $this->mTrxIdleCallbacks ) );
2666
2667                 if ( $e instanceof Exception ) {
2668                         throw $e; // re-throw any first exception
2669                 }
2670         }
2671
2672         /**
2673          * Actually run and consume any "on transaction pre-commit" callbacks.
2674          *
2675          * This method should not be used outside of Database/LoadBalancer
2676          *
2677          * @since 1.22
2678          * @throws Exception
2679          */
2680         public function runOnTransactionPreCommitCallbacks() {
2681                 $e = null; // first exception
2682                 do { // callbacks may add callbacks :)
2683                         $callbacks = $this->mTrxPreCommitCallbacks;
2684                         $this->mTrxPreCommitCallbacks = []; // consumed (and recursion guard)
2685                         foreach ( $callbacks as $callback ) {
2686                                 try {
2687                                         list( $phpCallback ) = $callback;
2688                                         call_user_func( $phpCallback );
2689                                 } catch ( Exception $ex ) {
2690                                         call_user_func( $this->errorLogger, $ex );
2691                                         $e = $e ?: $ex;
2692                                 }
2693                         }
2694                 } while ( count( $this->mTrxPreCommitCallbacks ) );
2695
2696                 if ( $e instanceof Exception ) {
2697                         throw $e; // re-throw any first exception
2698                 }
2699         }
2700
2701         /**
2702          * Actually run any "transaction listener" callbacks.
2703          *
2704          * This method should not be used outside of Database/LoadBalancer
2705          *
2706          * @param integer $trigger IDatabase::TRIGGER_* constant
2707          * @throws Exception
2708          * @since 1.20
2709          */
2710         public function runTransactionListenerCallbacks( $trigger ) {
2711                 if ( $this->mTrxEndCallbacksSuppressed ) {
2712                         return;
2713                 }
2714
2715                 /** @var Exception $e */
2716                 $e = null; // first exception
2717
2718                 foreach ( $this->mTrxRecurringCallbacks as $phpCallback ) {
2719                         try {
2720                                 $phpCallback( $trigger, $this );
2721                         } catch ( Exception $ex ) {
2722                                 call_user_func( $this->errorLogger, $ex );
2723                                 $e = $e ?: $ex;
2724                         }
2725                 }
2726
2727                 if ( $e instanceof Exception ) {
2728                         throw $e; // re-throw any first exception
2729                 }
2730         }
2731
2732         final public function startAtomic( $fname = __METHOD__ ) {
2733                 if ( !$this->mTrxLevel ) {
2734                         $this->begin( $fname, self::TRANSACTION_INTERNAL );
2735                         // If DBO_TRX is set, a series of startAtomic/endAtomic pairs will result
2736                         // in all changes being in one transaction to keep requests transactional.
2737                         if ( !$this->getFlag( self::DBO_TRX ) ) {
2738                                 $this->mTrxAutomaticAtomic = true;
2739                         }
2740                 }
2741
2742                 $this->mTrxAtomicLevels[] = $fname;
2743         }
2744
2745         final public function endAtomic( $fname = __METHOD__ ) {
2746                 if ( !$this->mTrxLevel ) {
2747                         throw new DBUnexpectedError( $this, "No atomic transaction is open (got $fname)." );
2748                 }
2749                 if ( !$this->mTrxAtomicLevels ||
2750                         array_pop( $this->mTrxAtomicLevels ) !== $fname
2751                 ) {
2752                         throw new DBUnexpectedError( $this, "Invalid atomic section ended (got $fname)." );
2753                 }
2754
2755                 if ( !$this->mTrxAtomicLevels && $this->mTrxAutomaticAtomic ) {
2756                         $this->commit( $fname, self::FLUSHING_INTERNAL );
2757                 }
2758         }
2759
2760         final public function doAtomicSection( $fname, callable $callback ) {
2761                 $this->startAtomic( $fname );
2762                 try {
2763                         $res = call_user_func_array( $callback, [ $this, $fname ] );
2764                 } catch ( Exception $e ) {
2765                         $this->rollback( $fname, self::FLUSHING_INTERNAL );
2766                         throw $e;
2767                 }
2768                 $this->endAtomic( $fname );
2769
2770                 return $res;
2771         }
2772
2773         final public function begin( $fname = __METHOD__, $mode = self::TRANSACTION_EXPLICIT ) {
2774                 // Protect against mismatched atomic section, transaction nesting, and snapshot loss
2775                 if ( $this->mTrxLevel ) {
2776                         if ( $this->mTrxAtomicLevels ) {
2777                                 $levels = implode( ', ', $this->mTrxAtomicLevels );
2778                                 $msg = "$fname: Got explicit BEGIN while atomic section(s) $levels are open.";
2779                                 throw new DBUnexpectedError( $this, $msg );
2780                         } elseif ( !$this->mTrxAutomatic ) {
2781                                 $msg = "$fname: Explicit transaction already active (from {$this->mTrxFname}).";
2782                                 throw new DBUnexpectedError( $this, $msg );
2783                         } else {
2784                                 // @TODO: make this an exception at some point
2785                                 $msg = "$fname: Implicit transaction already active (from {$this->mTrxFname}).";
2786                                 $this->queryLogger->error( $msg );
2787                                 return; // join the main transaction set
2788                         }
2789                 } elseif ( $this->getFlag( self::DBO_TRX ) && $mode !== self::TRANSACTION_INTERNAL ) {
2790                         // @TODO: make this an exception at some point
2791                         $msg = "$fname: Implicit transaction expected (DBO_TRX set).";
2792                         $this->queryLogger->error( $msg );
2793                         return; // let any writes be in the main transaction
2794                 }
2795
2796                 // Avoid fatals if close() was called
2797                 $this->assertOpen();
2798
2799                 $this->doBegin( $fname );
2800                 $this->mTrxTimestamp = microtime( true );
2801                 $this->mTrxFname = $fname;
2802                 $this->mTrxDoneWrites = false;
2803                 $this->mTrxAutomaticAtomic = false;
2804                 $this->mTrxAtomicLevels = [];
2805                 $this->mTrxShortId = sprintf( '%06x', mt_rand( 0, 0xffffff ) );
2806                 $this->mTrxWriteDuration = 0.0;
2807                 $this->mTrxWriteQueryCount = 0;
2808                 $this->mTrxWriteAdjDuration = 0.0;
2809                 $this->mTrxWriteAdjQueryCount = 0;
2810                 $this->mTrxWriteCallers = [];
2811                 // First SELECT after BEGIN will establish the snapshot in REPEATABLE-READ.
2812                 // Get an estimate of the replica DB lag before then, treating estimate staleness
2813                 // as lag itself just to be safe
2814                 $status = $this->getApproximateLagStatus();
2815                 $this->mTrxReplicaLag = $status['lag'] + ( microtime( true ) - $status['since'] );
2816                 // T147697: make explicitTrxActive() return true until begin() finishes. This way, no
2817                 // caller will think its OK to muck around with the transaction just because startAtomic()
2818                 // has not yet completed (e.g. setting mTrxAtomicLevels).
2819                 $this->mTrxAutomatic = ( $mode === self::TRANSACTION_INTERNAL );
2820         }
2821
2822         /**
2823          * Issues the BEGIN command to the database server.
2824          *
2825          * @see Database::begin()
2826          * @param string $fname
2827          */
2828         protected function doBegin( $fname ) {
2829                 $this->query( 'BEGIN', $fname );
2830                 $this->mTrxLevel = 1;
2831         }
2832
2833         final public function commit( $fname = __METHOD__, $flush = '' ) {
2834                 if ( $this->mTrxLevel && $this->mTrxAtomicLevels ) {
2835                         // There are still atomic sections open. This cannot be ignored
2836                         $levels = implode( ', ', $this->mTrxAtomicLevels );
2837                         throw new DBUnexpectedError(
2838                                 $this,
2839                                 "$fname: Got COMMIT while atomic sections $levels are still open."
2840                         );
2841                 }
2842
2843                 if ( $flush === self::FLUSHING_INTERNAL || $flush === self::FLUSHING_ALL_PEERS ) {
2844                         if ( !$this->mTrxLevel ) {
2845                                 return; // nothing to do
2846                         } elseif ( !$this->mTrxAutomatic ) {
2847                                 throw new DBUnexpectedError(
2848                                         $this,
2849                                         "$fname: Flushing an explicit transaction, getting out of sync."
2850                                 );
2851                         }
2852                 } else {
2853                         if ( !$this->mTrxLevel ) {
2854                                 $this->queryLogger->error(
2855                                         "$fname: No transaction to commit, something got out of sync." );
2856                                 return; // nothing to do
2857                         } elseif ( $this->mTrxAutomatic ) {
2858                                 // @TODO: make this an exception at some point
2859                                 $msg = "$fname: Explicit commit of implicit transaction.";
2860                                 $this->queryLogger->error( $msg );
2861                                 return; // wait for the main transaction set commit round
2862                         }
2863                 }
2864
2865                 // Avoid fatals if close() was called
2866                 $this->assertOpen();
2867
2868                 $this->runOnTransactionPreCommitCallbacks();
2869                 $writeTime = $this->pendingWriteQueryDuration( self::ESTIMATE_DB_APPLY );
2870                 $this->doCommit( $fname );
2871                 if ( $this->mTrxDoneWrites ) {
2872                         $this->mLastWriteTime = microtime( true );
2873                         $this->trxProfiler->transactionWritingOut(
2874                                 $this->mServer, $this->mDBname, $this->mTrxShortId, $writeTime );
2875                 }
2876
2877                 $this->runOnTransactionIdleCallbacks( self::TRIGGER_COMMIT );
2878                 $this->runTransactionListenerCallbacks( self::TRIGGER_COMMIT );
2879         }
2880
2881         /**
2882          * Issues the COMMIT command to the database server.
2883          *
2884          * @see Database::commit()
2885          * @param string $fname
2886          */
2887         protected function doCommit( $fname ) {
2888                 if ( $this->mTrxLevel ) {
2889                         $this->query( 'COMMIT', $fname );
2890                         $this->mTrxLevel = 0;
2891                 }
2892         }
2893
2894         final public function rollback( $fname = __METHOD__, $flush = '' ) {
2895                 if ( $flush === self::FLUSHING_INTERNAL || $flush === self::FLUSHING_ALL_PEERS ) {
2896                         if ( !$this->mTrxLevel ) {
2897                                 return; // nothing to do
2898                         }
2899                 } else {
2900                         if ( !$this->mTrxLevel ) {
2901                                 $this->queryLogger->error(
2902                                         "$fname: No transaction to rollback, something got out of sync." );
2903                                 return; // nothing to do
2904                         } elseif ( $this->getFlag( self::DBO_TRX ) ) {
2905                                 throw new DBUnexpectedError(
2906                                         $this,
2907                                         "$fname: Expected mass rollback of all peer databases (DBO_TRX set)."
2908                                 );
2909                         }
2910                 }
2911
2912                 // Avoid fatals if close() was called
2913                 $this->assertOpen();
2914
2915                 $this->doRollback( $fname );
2916                 $this->mTrxAtomicLevels = [];
2917                 if ( $this->mTrxDoneWrites ) {
2918                         $this->trxProfiler->transactionWritingOut(
2919                                 $this->mServer, $this->mDBname, $this->mTrxShortId );
2920                 }
2921
2922                 $this->mTrxIdleCallbacks = []; // clear
2923                 $this->mTrxPreCommitCallbacks = []; // clear
2924                 $this->runOnTransactionIdleCallbacks( self::TRIGGER_ROLLBACK );
2925                 $this->runTransactionListenerCallbacks( self::TRIGGER_ROLLBACK );
2926         }
2927
2928         /**
2929          * Issues the ROLLBACK command to the database server.
2930          *
2931          * @see Database::rollback()
2932          * @param string $fname
2933          */
2934         protected function doRollback( $fname ) {
2935                 if ( $this->mTrxLevel ) {
2936                         # Disconnects cause rollback anyway, so ignore those errors
2937                         $ignoreErrors = true;
2938                         $this->query( 'ROLLBACK', $fname, $ignoreErrors );
2939                         $this->mTrxLevel = 0;
2940                 }
2941         }
2942
2943         public function flushSnapshot( $fname = __METHOD__ ) {
2944                 if ( $this->writesOrCallbacksPending() || $this->explicitTrxActive() ) {
2945                         // This only flushes transactions to clear snapshots, not to write data
2946                         $fnames = implode( ', ', $this->pendingWriteAndCallbackCallers() );
2947                         throw new DBUnexpectedError(
2948                                 $this,
2949                                 "$fname: Cannot flush snapshot because writes are pending ($fnames)."
2950                         );
2951                 }
2952
2953                 $this->commit( $fname, self::FLUSHING_INTERNAL );
2954         }
2955
2956         public function explicitTrxActive() {
2957                 return $this->mTrxLevel && ( $this->mTrxAtomicLevels || !$this->mTrxAutomatic );
2958         }
2959
2960         public function duplicateTableStructure(
2961                 $oldName, $newName, $temporary = false, $fname = __METHOD__
2962         ) {
2963                 throw new RuntimeException( __METHOD__ . ' is not implemented in descendant class' );
2964         }
2965
2966         public function listTables( $prefix = null, $fname = __METHOD__ ) {
2967                 throw new RuntimeException( __METHOD__ . ' is not implemented in descendant class' );
2968         }
2969
2970         public function listViews( $prefix = null, $fname = __METHOD__ ) {
2971                 throw new RuntimeException( __METHOD__ . ' is not implemented in descendant class' );
2972         }
2973
2974         public function timestamp( $ts = 0 ) {
2975                 $t = new ConvertibleTimestamp( $ts );
2976                 // Let errors bubble up to avoid putting garbage in the DB
2977                 return $t->getTimestamp( TS_MW );
2978         }
2979
2980         public function timestampOrNull( $ts = null ) {
2981                 if ( is_null( $ts ) ) {
2982                         return null;
2983                 } else {
2984                         return $this->timestamp( $ts );
2985                 }
2986         }
2987
2988         /**
2989          * Take the result from a query, and wrap it in a ResultWrapper if
2990          * necessary. Boolean values are passed through as is, to indicate success
2991          * of write queries or failure.
2992          *
2993          * Once upon a time, Database::query() returned a bare MySQL result
2994          * resource, and it was necessary to call this function to convert it to
2995          * a wrapper. Nowadays, raw database objects are never exposed to external
2996          * callers, so this is unnecessary in external code.
2997          *
2998          * @param bool|ResultWrapper|resource|object $result
2999          * @return bool|ResultWrapper
3000          */
3001         protected function resultObject( $result ) {
3002                 if ( !$result ) {
3003                         return false;
3004                 } elseif ( $result instanceof ResultWrapper ) {
3005                         return $result;
3006                 } elseif ( $result === true ) {
3007                         // Successful write query
3008                         return $result;
3009                 } else {
3010                         return new ResultWrapper( $this, $result );
3011                 }
3012         }
3013
3014         public function ping( &$rtt = null ) {
3015                 // Avoid hitting the server if it was hit recently
3016                 if ( $this->isOpen() && ( microtime( true ) - $this->lastPing ) < self::PING_TTL ) {
3017                         if ( !func_num_args() || $this->mRTTEstimate > 0 ) {
3018                                 $rtt = $this->mRTTEstimate;
3019                                 return true; // don't care about $rtt
3020                         }
3021                 }
3022
3023                 // This will reconnect if possible or return false if not
3024                 $this->clearFlag( self::DBO_TRX, self::REMEMBER_PRIOR );
3025                 $ok = ( $this->query( self::PING_QUERY, __METHOD__, true ) !== false );
3026                 $this->restoreFlags( self::RESTORE_PRIOR );
3027
3028                 if ( $ok ) {
3029                         $rtt = $this->mRTTEstimate;
3030                 }
3031
3032                 return $ok;
3033         }
3034
3035         /**
3036          * Close existing database connection and open a new connection
3037          *
3038          * @return bool True if new connection is opened successfully, false if error
3039          */
3040         protected function reconnect() {
3041                 $this->closeConnection();
3042                 $this->mOpened = false;
3043                 $this->mConn = false;
3044                 try {
3045                         $this->open( $this->mServer, $this->mUser, $this->mPassword, $this->mDBname );
3046                         $this->lastPing = microtime( true );
3047                         $ok = true;
3048                 } catch ( DBConnectionError $e ) {
3049                         $ok = false;
3050                 }
3051
3052                 return $ok;
3053         }
3054
3055         public function getSessionLagStatus() {
3056                 return $this->getTransactionLagStatus() ?: $this->getApproximateLagStatus();
3057         }
3058
3059         /**
3060          * Get the replica DB lag when the current transaction started
3061          *
3062          * This is useful when transactions might use snapshot isolation
3063          * (e.g. REPEATABLE-READ in innodb), so the "real" lag of that data
3064          * is this lag plus transaction duration. If they don't, it is still
3065          * safe to be pessimistic. This returns null if there is no transaction.
3066          *
3067          * @return array|null ('lag': seconds or false on error, 'since': UNIX timestamp of BEGIN)
3068          * @since 1.27
3069          */
3070         protected function getTransactionLagStatus() {
3071                 return $this->mTrxLevel
3072                         ? [ 'lag' => $this->mTrxReplicaLag, 'since' => $this->trxTimestamp() ]
3073                         : null;
3074         }
3075
3076         /**
3077          * Get a replica DB lag estimate for this server
3078          *
3079          * @return array ('lag': seconds or false on error, 'since': UNIX timestamp of estimate)
3080          * @since 1.27
3081          */
3082         protected function getApproximateLagStatus() {
3083                 return [
3084                         'lag'   => $this->getLBInfo( 'replica' ) ? $this->getLag() : 0,
3085                         'since' => microtime( true )
3086                 ];
3087         }
3088
3089         /**
3090          * Merge the result of getSessionLagStatus() for several DBs
3091          * using the most pessimistic values to estimate the lag of
3092          * any data derived from them in combination
3093          *
3094          * This is information is useful for caching modules
3095          *
3096          * @see WANObjectCache::set()
3097          * @see WANObjectCache::getWithSetCallback()
3098          *
3099          * @param IDatabase $db1
3100          * @param IDatabase ...
3101          * @return array Map of values:
3102          *   - lag: highest lag of any of the DBs or false on error (e.g. replication stopped)
3103          *   - since: oldest UNIX timestamp of any of the DB lag estimates
3104          *   - pending: whether any of the DBs have uncommitted changes
3105          * @since 1.27
3106          */
3107         public static function getCacheSetOptions( IDatabase $db1 ) {
3108                 $res = [ 'lag' => 0, 'since' => INF, 'pending' => false ];
3109                 foreach ( func_get_args() as $db ) {
3110                         /** @var IDatabase $db */
3111                         $status = $db->getSessionLagStatus();
3112                         if ( $status['lag'] === false ) {
3113                                 $res['lag'] = false;
3114                         } elseif ( $res['lag'] !== false ) {
3115                                 $res['lag'] = max( $res['lag'], $status['lag'] );
3116                         }
3117                         $res['since'] = min( $res['since'], $status['since'] );
3118                         $res['pending'] = $res['pending'] ?: $db->writesPending();
3119                 }
3120
3121                 return $res;
3122         }
3123
3124         public function getLag() {
3125                 return 0;
3126         }
3127
3128         public function maxListLen() {
3129                 return 0;
3130         }
3131
3132         public function encodeBlob( $b ) {
3133                 return $b;
3134         }
3135
3136         public function decodeBlob( $b ) {
3137                 if ( $b instanceof Blob ) {
3138                         $b = $b->fetch();
3139                 }
3140                 return $b;
3141         }
3142
3143         public function setSessionOptions( array $options ) {
3144         }
3145
3146         public function sourceFile(
3147                 $filename,
3148                 callable $lineCallback = null,
3149                 callable $resultCallback = null,
3150                 $fname = false,
3151                 callable $inputCallback = null
3152         ) {
3153                 MediaWiki\suppressWarnings();
3154                 $fp = fopen( $filename, 'r' );
3155                 MediaWiki\restoreWarnings();
3156
3157                 if ( false === $fp ) {
3158                         throw new RuntimeException( "Could not open \"{$filename}\".\n" );
3159                 }
3160
3161                 if ( !$fname ) {
3162                         $fname = __METHOD__ . "( $filename )";
3163                 }
3164
3165                 try {
3166                         $error = $this->sourceStream(
3167                                 $fp, $lineCallback, $resultCallback, $fname, $inputCallback );
3168                 } catch ( Exception $e ) {
3169                         fclose( $fp );
3170                         throw $e;
3171                 }
3172
3173                 fclose( $fp );
3174
3175                 return $error;
3176         }
3177
3178         public function setSchemaVars( $vars ) {
3179                 $this->mSchemaVars = $vars;
3180         }
3181
3182         public function sourceStream(
3183                 $fp,
3184                 callable $lineCallback = null,
3185                 callable $resultCallback = null,
3186                 $fname = __METHOD__,
3187                 callable $inputCallback = null
3188         ) {
3189                 $cmd = '';
3190
3191                 while ( !feof( $fp ) ) {
3192                         if ( $lineCallback ) {
3193                                 call_user_func( $lineCallback );
3194                         }
3195
3196                         $line = trim( fgets( $fp ) );
3197
3198                         if ( $line == '' ) {
3199                                 continue;
3200                         }
3201
3202                         if ( '-' == $line[0] && '-' == $line[1] ) {
3203                                 continue;
3204                         }
3205
3206                         if ( $cmd != '' ) {
3207                                 $cmd .= ' ';
3208                         }
3209
3210                         $done = $this->streamStatementEnd( $cmd, $line );
3211
3212                         $cmd .= "$line\n";
3213
3214                         if ( $done || feof( $fp ) ) {
3215                                 $cmd = $this->replaceVars( $cmd );
3216
3217                                 if ( !$inputCallback || call_user_func( $inputCallback, $cmd ) ) {
3218                                         $res = $this->query( $cmd, $fname );
3219
3220                                         if ( $resultCallback ) {
3221                                                 call_user_func( $resultCallback, $res, $this );
3222                                         }
3223
3224                                         if ( false === $res ) {
3225                                                 $err = $this->lastError();
3226
3227                                                 return "Query \"{$cmd}\" failed with error code \"$err\".\n";
3228                                         }
3229                                 }
3230                                 $cmd = '';
3231                         }
3232                 }
3233
3234                 return true;
3235         }
3236
3237         /**
3238          * Called by sourceStream() to check if we've reached a statement end
3239          *
3240          * @param string &$sql SQL assembled so far
3241          * @param string &$newLine New line about to be added to $sql
3242          * @return bool Whether $newLine contains end of the statement
3243          */
3244         public function streamStatementEnd( &$sql, &$newLine ) {
3245                 if ( $this->delimiter ) {
3246                         $prev = $newLine;
3247                         $newLine = preg_replace(
3248                                 '/' . preg_quote( $this->delimiter, '/' ) . '$/', '', $newLine );
3249                         if ( $newLine != $prev ) {
3250                                 return true;
3251                         }
3252                 }
3253
3254                 return false;
3255         }
3256
3257         /**
3258          * Database independent variable replacement. Replaces a set of variables
3259          * in an SQL statement with their contents as given by $this->getSchemaVars().
3260          *
3261          * Supports '{$var}' `{$var}` and / *$var* / (without the spaces) style variables.
3262          *
3263          * - '{$var}' should be used for text and is passed through the database's
3264          *   addQuotes method.
3265          * - `{$var}` should be used for identifiers (e.g. table and database names).
3266          *   It is passed through the database's addIdentifierQuotes method which
3267          *   can be overridden if the database uses something other than backticks.
3268          * - / *_* / or / *$wgDBprefix* / passes the name that follows through the
3269          *   database's tableName method.
3270          * - / *i* / passes the name that follows through the database's indexName method.
3271          * - In all other cases, / *$var* / is left unencoded. Except for table options,
3272          *   its use should be avoided. In 1.24 and older, string encoding was applied.
3273          *
3274          * @param string $ins SQL statement to replace variables in
3275          * @return string The new SQL statement with variables replaced
3276          */
3277         protected function replaceVars( $ins ) {
3278                 $vars = $this->getSchemaVars();
3279                 return preg_replace_callback(
3280                         '!
3281                                 /\* (\$wgDBprefix|[_i]) \*/ (\w*) | # 1-2. tableName, indexName
3282                                 \'\{\$ (\w+) }\'                  | # 3. addQuotes
3283                                 `\{\$ (\w+) }`                    | # 4. addIdentifierQuotes
3284                                 /\*\$ (\w+) \*/                     # 5. leave unencoded
3285                         !x',
3286                         function ( $m ) use ( $vars ) {
3287                                 // Note: Because of <https://bugs.php.net/bug.php?id=51881>,
3288                                 // check for both nonexistent keys *and* the empty string.
3289                                 if ( isset( $m[1] ) && $m[1] !== '' ) {
3290                                         if ( $m[1] === 'i' ) {
3291                                                 return $this->indexName( $m[2] );
3292                                         } else {
3293                                                 return $this->tableName( $m[2] );
3294                                         }
3295                                 } elseif ( isset( $m[3] ) && $m[3] !== '' && array_key_exists( $m[3], $vars ) ) {
3296                                         return $this->addQuotes( $vars[$m[3]] );
3297                                 } elseif ( isset( $m[4] ) && $m[4] !== '' && array_key_exists( $m[4], $vars ) ) {
3298                                         return $this->addIdentifierQuotes( $vars[$m[4]] );
3299                                 } elseif ( isset( $m[5] ) && $m[5] !== '' && array_key_exists( $m[5], $vars ) ) {
3300                                         return $vars[$m[5]];
3301                                 } else {
3302                                         return $m[0];
3303                                 }
3304                         },
3305                         $ins
3306                 );
3307         }
3308
3309         /**
3310          * Get schema variables. If none have been set via setSchemaVars(), then
3311          * use some defaults from the current object.
3312          *
3313          * @return array
3314          */
3315         protected function getSchemaVars() {
3316                 if ( $this->mSchemaVars ) {
3317                         return $this->mSchemaVars;
3318                 } else {
3319                         return $this->getDefaultSchemaVars();
3320                 }
3321         }
3322
3323         /**
3324          * Get schema variables to use if none have been set via setSchemaVars().
3325          *
3326          * Override this in derived classes to provide variables for tables.sql
3327          * and SQL patch files.
3328          *
3329          * @return array
3330          */
3331         protected function getDefaultSchemaVars() {
3332                 return [];
3333         }
3334
3335         public function lockIsFree( $lockName, $method ) {
3336                 return true;
3337         }
3338
3339         public function lock( $lockName, $method, $timeout = 5 ) {
3340                 $this->mNamedLocksHeld[$lockName] = 1;
3341
3342                 return true;
3343         }
3344
3345         public function unlock( $lockName, $method ) {
3346                 unset( $this->mNamedLocksHeld[$lockName] );
3347
3348                 return true;
3349         }
3350
3351         public function getScopedLockAndFlush( $lockKey, $fname, $timeout ) {
3352                 if ( $this->writesOrCallbacksPending() ) {
3353                         // This only flushes transactions to clear snapshots, not to write data
3354                         $fnames = implode( ', ', $this->pendingWriteAndCallbackCallers() );
3355                         throw new DBUnexpectedError(
3356                                 $this,
3357                                 "$fname: Cannot flush pre-lock snapshot because writes are pending ($fnames)."
3358                         );
3359                 }
3360
3361                 if ( !$this->lock( $lockKey, $fname, $timeout ) ) {
3362                         return null;
3363                 }
3364
3365                 $unlocker = new ScopedCallback( function () use ( $lockKey, $fname ) {
3366                         if ( $this->trxLevel() ) {
3367                                 // There is a good chance an exception was thrown, causing any early return
3368                                 // from the caller. Let any error handler get a chance to issue rollback().
3369                                 // If there isn't one, let the error bubble up and trigger server-side rollback.
3370                                 $this->onTransactionResolution(
3371                                         function () use ( $lockKey, $fname ) {
3372                                                 $this->unlock( $lockKey, $fname );
3373                                         },
3374                                         $fname
3375                                 );
3376                         } else {
3377                                 $this->unlock( $lockKey, $fname );
3378                         }
3379                 } );
3380
3381                 $this->commit( $fname, self::FLUSHING_INTERNAL );
3382
3383                 return $unlocker;
3384         }
3385
3386         public function namedLocksEnqueue() {
3387                 return false;
3388         }
3389
3390         public function tableLocksHaveTransactionScope() {
3391                 return true;
3392         }
3393
3394         final public function lockTables( array $read, array $write, $method ) {
3395                 if ( $this->writesOrCallbacksPending() ) {
3396                         throw new DBUnexpectedError( $this, "Transaction writes or callbacks still pending." );
3397                 }
3398
3399                 if ( $this->tableLocksHaveTransactionScope() ) {
3400                         $this->startAtomic( $method );
3401                 }
3402
3403                 return $this->doLockTables( $read, $write, $method );
3404         }
3405
3406         /**
3407          * Helper function for lockTables() that handles the actual table locking
3408          *
3409          * @param array $read Array of tables to lock for read access
3410          * @param array $write Array of tables to lock for write access
3411          * @param string $method Name of caller
3412          * @return true
3413          */
3414         protected function doLockTables( array $read, array $write, $method ) {
3415                 return true;
3416         }
3417
3418         final public function unlockTables( $method ) {
3419                 if ( $this->tableLocksHaveTransactionScope() ) {
3420                         $this->endAtomic( $method );
3421
3422                         return true; // locks released on COMMIT/ROLLBACK
3423                 }
3424
3425                 return $this->doUnlockTables( $method );
3426         }
3427
3428         /**
3429          * Helper function for unlockTables() that handles the actual table unlocking
3430          *
3431          * @param string $method Name of caller
3432          * @return true
3433          */
3434         protected function doUnlockTables( $method ) {
3435                 return true;
3436         }
3437
3438         /**
3439          * Delete a table
3440          * @param string $tableName
3441          * @param string $fName
3442          * @return bool|ResultWrapper
3443          * @since 1.18
3444          */
3445         public function dropTable( $tableName, $fName = __METHOD__ ) {
3446                 if ( !$this->tableExists( $tableName, $fName ) ) {
3447                         return false;
3448                 }
3449                 $sql = "DROP TABLE " . $this->tableName( $tableName ) . " CASCADE";
3450
3451                 return $this->query( $sql, $fName );
3452         }
3453
3454         public function getInfinity() {
3455                 return 'infinity';
3456         }
3457
3458         public function encodeExpiry( $expiry ) {
3459                 return ( $expiry == '' || $expiry == 'infinity' || $expiry == $this->getInfinity() )
3460                         ? $this->getInfinity()
3461                         : $this->timestamp( $expiry );
3462         }
3463
3464         public function decodeExpiry( $expiry, $format = TS_MW ) {
3465                 if ( $expiry == '' || $expiry == 'infinity' || $expiry == $this->getInfinity() ) {
3466                         return 'infinity';
3467                 }
3468
3469                 return ConvertibleTimestamp::convert( $format, $expiry );
3470         }
3471
3472         public function setBigSelects( $value = true ) {
3473                 // no-op
3474         }
3475
3476         public function isReadOnly() {
3477                 return ( $this->getReadOnlyReason() !== false );
3478         }
3479
3480         /**
3481          * @return string|bool Reason this DB is read-only or false if it is not
3482          */
3483         protected function getReadOnlyReason() {
3484                 $reason = $this->getLBInfo( 'readOnlyReason' );
3485
3486                 return is_string( $reason ) ? $reason : false;
3487         }
3488
3489         public function setTableAliases( array $aliases ) {
3490                 $this->tableAliases = $aliases;
3491         }
3492
3493         /**
3494          * @return bool Whether a DB user is required to access the DB
3495          * @since 1.28
3496          */
3497         protected function requiresDatabaseUser() {
3498                 return true;
3499         }
3500
3501         /**
3502          * Get the underlying binding handle, mConn
3503          *
3504          * Makes sure that mConn is set (disconnects and ping() failure can unset it).
3505          * This catches broken callers than catch and ignore disconnection exceptions.
3506          * Unlike checking isOpen(), this is safe to call inside of open().
3507          *
3508          * @return resource|object
3509          * @throws DBUnexpectedError
3510          * @since 1.26
3511          */
3512         protected function getBindingHandle() {
3513                 if ( !$this->mConn ) {
3514                         throw new DBUnexpectedError(
3515                                 $this,
3516                                 'DB connection was already closed or the connection dropped.'
3517                         );
3518                 }
3519
3520                 return $this->mConn;
3521         }
3522
3523         /**
3524          * @since 1.19
3525          * @return string
3526          */
3527         public function __toString() {
3528                 return (string)$this->mConn;
3529         }
3530
3531         /**
3532          * Make sure that copies do not share the same client binding handle
3533          * @throws DBConnectionError
3534          */
3535         public function __clone() {
3536                 $this->connLogger->warning(
3537                         "Cloning " . static::class . " is not recomended; forking connection:\n" .
3538                         ( new RuntimeException() )->getTraceAsString()
3539                 );
3540
3541                 if ( $this->isOpen() ) {
3542                         // Open a new connection resource without messing with the old one
3543                         $this->mOpened = false;
3544                         $this->mConn = false;
3545                         $this->mTrxEndCallbacks = []; // don't copy
3546                         $this->handleSessionLoss(); // no trx or locks anymore
3547                         $this->open( $this->mServer, $this->mUser, $this->mPassword, $this->mDBname );
3548                         $this->lastPing = microtime( true );
3549                 }
3550         }
3551
3552         /**
3553          * Called by serialize. Throw an exception when DB connection is serialized.
3554          * This causes problems on some database engines because the connection is
3555          * not restored on unserialize.
3556          */
3557         public function __sleep() {
3558                 throw new RuntimeException( 'Database serialization may cause problems, since ' .
3559                         'the connection is not restored on wakeup.' );
3560         }
3561
3562         /**
3563          * Run a few simple sanity checks and close dangling connections
3564          */
3565         public function __destruct() {
3566                 if ( $this->mTrxLevel && $this->mTrxDoneWrites ) {
3567                         trigger_error( "Uncommitted DB writes (transaction from {$this->mTrxFname})." );
3568                 }
3569
3570                 $danglingWriters = $this->pendingWriteAndCallbackCallers();
3571                 if ( $danglingWriters ) {
3572                         $fnames = implode( ', ', $danglingWriters );
3573                         trigger_error( "DB transaction writes or callbacks still pending ($fnames)." );
3574                 }
3575
3576                 if ( $this->mConn ) {
3577                         // Avoid connection leaks for sanity. Normally, resources close at script completion.
3578                         // The connection might already be closed in zend/hhvm by now, so suppress warnings.
3579                         \MediaWiki\suppressWarnings();
3580                         $this->closeConnection();
3581                         \MediaWiki\restoreWarnings();
3582                         $this->mConn = false;
3583                         $this->mOpened = false;
3584                 }
3585         }
3586 }
3587
3588 class_alias( Database::class, 'DatabaseBase' ); // b/c for old name
3589 class_alias( Database::class, 'Database' ); // b/c global alias