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 use Psr\Log\LoggerAwareInterface;
  27 use Psr\Log\LoggerInterface;
  28 use Wikimedia\ScopedCallback;
  29
  30 /**
  31  * Relational database abstraction object
  32  *
  33  * @ingroup Database
  34  * @since 1.28
  35  */
  36 abstract class Database implements IDatabase, IMaintainableDatabase, LoggerAwareInterface {
  37         /** Number of times to re-try an operation in case of deadlock */
  38         const DEADLOCK_TRIES = 4;
  39         /** Minimum time to wait before retry, in microseconds */
  40         const DEADLOCK_DELAY_MIN = 500000;
  41         /** Maximum time to wait before retry */
  42         const DEADLOCK_DELAY_MAX = 1500000;
  43
  44         /** How long before it is worth doing a dummy query to test the connection */
  45         const PING_TTL = 1.0;
  46         const PING_QUERY = 'SELECT 1 AS ping';
  47
  48         const TINY_WRITE_SEC = .010;
  49         const SLOW_WRITE_SEC = .500;
  50         const SMALL_WRITE_ROWS = 100;
  51
  52         /** @var string SQL query */
  53         protected $mLastQuery = '';
  54         /** @var float|bool UNIX timestamp of last write query */
  55         protected $mLastWriteTime = false;
  56         /** @var string|bool */
  57         protected $mPHPError = false;
  58         /** @var string */
  59         protected $mServer;
  60         /** @var string */
  61         protected $mUser;
  62         /** @var string */
  63         protected $mPassword;
  64         /** @var string */
  65         protected $mDBname;
  66         /** @var array[] $aliases Map of (table => (dbname, schema, prefix) map) */
  67         protected $tableAliases = [];
  68         /** @var bool Whether this PHP instance is for a CLI script */
  69         protected $cliMode;
  70         /** @var string Agent name for query profiling */
  71         protected $agent;
  72
  73         /** @var BagOStuff APC cache */
  74         protected $srvCache;
  75         /** @var LoggerInterface */
  76         protected $connLogger;
  77         /** @var LoggerInterface */
  78         protected $queryLogger;
  79         /** @var callback Error logging callback */
  80         protected $errorLogger;
  81
  82         /** @var resource Database connection */
  83         protected $mConn = null;
  84         /** @var bool */
  85         protected $mOpened = false;
  86
  87         /** @var array[] List of (callable, method name) */
  88         protected $mTrxIdleCallbacks = [];
  89         /** @var array[] List of (callable, method name) */
  90         protected $mTrxPreCommitCallbacks = [];
  91         /** @var array[] List of (callable, method name) */
  92         protected $mTrxEndCallbacks = [];
  93         /** @var callable[] Map of (name => callable) */
  94         protected $mTrxRecurringCallbacks = [];
  95         /** @var bool Whether to suppress triggering of transaction end callbacks */
  96         protected $mTrxEndCallbacksSuppressed = false;
  97
  98         /** @var string */
  99         protected $mTablePrefix = '';
 100         /** @var string */
 101         protected $mSchema = '';
 102         /** @var integer */
 103         protected $mFlags;
 104         /** @var array */
 105         protected $mLBInfo = [];
 106         /** @var bool|null */
 107         protected $mDefaultBigSelects = null;
 108         /** @var array|bool */
 109         protected $mSchemaVars = false;
 110         /** @var array */
 111         protected $mSessionVars = [];
 112         /** @var array|null */
 113         protected $preparedArgs;
 114         /** @var string|bool|null Stashed value of html_errors INI setting */
 115         protected $htmlErrors;
 116         /** @var string */
 117         protected $delimiter = ';';
 118         /** @var DatabaseDomain */
 119         protected $currentDomain;
 120
 121         /**
 122          * Either 1 if a transaction is active or 0 otherwise.
 123          * The other Trx fields may not be meaningfull if this is 0.
 124          *
 125          * @var int
 126          */
 127         protected $mTrxLevel = 0;
 128         /**
 129          * Either a short hexidecimal string if a transaction is active or ""
 130          *
 131          * @var string
 132          * @see Database::mTrxLevel
 133          */
 134         protected $mTrxShortId = '';
 135         /**
 136          * The UNIX time that the transaction started. Callers can assume that if
 137          * snapshot isolation is used, then the data is *at least* up to date to that
 138          * point (possibly more up-to-date since the first SELECT defines the snapshot).
 139          *
 140          * @var float|null
 141          * @see Database::mTrxLevel
 142          */
 143         private $mTrxTimestamp = null;
 144         /** @var float Lag estimate at the time of BEGIN */
 145         private $mTrxReplicaLag = null;
 146         /**
 147          * Remembers the function name given for starting the most recent transaction via begin().
 148          * Used to provide additional context for error reporting.
 149          *
 150          * @var string
 151          * @see Database::mTrxLevel
 152          */
 153         private $mTrxFname = null;
 154         /**
 155          * Record if possible write queries were done in the last transaction started
 156          *
 157          * @var bool
 158          * @see Database::mTrxLevel
 159          */
 160         private $mTrxDoneWrites = false;
 161         /**
 162          * Record if the current transaction was started implicitly due to DBO_TRX being set.
 163          *
 164          * @var bool
 165          * @see Database::mTrxLevel
 166          */
 167         private $mTrxAutomatic = false;
 168         /**
 169          * Array of levels of atomicity within transactions
 170          *
 171          * @var array
 172          */
 173         private $mTrxAtomicLevels = [];
 174         /**
 175          * Record if the current transaction was started implicitly by Database::startAtomic
 176          *
 177          * @var bool
 178          */
 179         private $mTrxAutomaticAtomic = false;
 180         /**
 181          * Track the write query callers of the current transaction
 182          *
 183          * @var string[]
 184          */
 185         private $mTrxWriteCallers = [];
 186         /**
 187          * @var float Seconds spent in write queries for the current transaction
 188          */
 189         private $mTrxWriteDuration = 0.0;
 190         /**
 191          * @var integer Number of write queries for the current transaction
 192          */
 193         private $mTrxWriteQueryCount = 0;
 194         /**
 195          * @var float Like mTrxWriteQueryCount but excludes lock-bound, easy to replicate, queries
 196          */
 197         private $mTrxWriteAdjDuration = 0.0;
 198         /**
 199          * @var integer Number of write queries counted in mTrxWriteAdjDuration
 200          */
 201         private $mTrxWriteAdjQueryCount = 0;
 202         /**
 203          * @var float RTT time estimate
 204          */
 205         private $mRTTEstimate = 0.0;
 206
 207         /** @var array Map of (name => 1) for locks obtained via lock() */
 208         private $mNamedLocksHeld = [];
 209         /** @var array Map of (table name => 1) for TEMPORARY tables */
 210         protected $mSessionTempTables = [];
 211
 212         /** @var IDatabase|null Lazy handle to the master DB this server replicates from */
 213         private $lazyMasterHandle;
 214
 215         /** @var float UNIX timestamp */
 216         protected $lastPing = 0.0;
 217
 218         /** @var int[] Prior mFlags values */
 219         private $priorFlags = [];
 220
 221         /** @var object|string Class name or object With profileIn/profileOut methods */
 222         protected $profiler;
 223         /** @var TransactionProfiler */
 224         protected $trxProfiler;
 225
 226         /**
 227          * Constructor and database handle and attempt to connect to the DB server
 228          *
 229          * IDatabase classes should not be constructed directly in external
 230          * code. Database::factory() should be used instead.
 231          *
 232          * @param array $params Parameters passed from Database::factory()
 233          */
 234         function __construct( array $params ) {
 235                 $server = $params['host'];
 236                 $user = $params['user'];
 237                 $password = $params['password'];
 238                 $dbName = $params['dbname'];
 239
 240                 $this->mSchema = $params['schema'];
 241                 $this->mTablePrefix = $params['tablePrefix'];
 242
 243                 $this->cliMode = $params['cliMode'];
 244                 // Agent name is added to SQL queries in a comment, so make sure it can't break out
 245                 $this->agent = str_replace( '/', '-', $params['agent'] );
 246
 247                 $this->mFlags = $params['flags'];
 248                 if ( $this->mFlags & self::DBO_DEFAULT ) {
 249                         if ( $this->cliMode ) {
 250                                 $this->mFlags &= ~self::DBO_TRX;
 251                         } else {
 252                                 $this->mFlags |= self::DBO_TRX;
 253                         }
 254                 }
 255
 256                 $this->mSessionVars = $params['variables'];
 257
 258                 $this->srvCache = isset( $params['srvCache'] )
 259                         ? $params['srvCache']
 260                         : new HashBagOStuff();
 261
 262                 $this->profiler = $params['profiler'];
 263                 $this->trxProfiler = $params['trxProfiler'];
 264                 $this->connLogger = $params['connLogger'];
 265                 $this->queryLogger = $params['queryLogger'];
 266                 $this->errorLogger = $params['errorLogger'];
 267
 268                 // Set initial dummy domain until open() sets the final DB/prefix
 269                 $this->currentDomain = DatabaseDomain::newUnspecified();
 270
 271                 if ( $user ) {
 272                         $this->open( $server, $user, $password, $dbName );
 273                 } elseif ( $this->requiresDatabaseUser() ) {
 274                         throw new InvalidArgumentException( "No database user provided." );
 275                 }
 276
 277                 // Set the domain object after open() sets the relevant fields
 278                 if ( $this->mDBname != '' ) {
 279                         // Domains with server scope but a table prefix are not used by IDatabase classes
 280                         $this->currentDomain = new DatabaseDomain( $this->mDBname, null, $this->mTablePrefix );
 281                 }
 282         }
 283
 284         /**
 285          * Construct a Database subclass instance given a database type and parameters
 286          *
 287          * This also connects to the database immediately upon object construction
 288          *
 289          * @param string $dbType A possible DB type (sqlite, mysql, postgres)
 290          * @param array $p Parameter map with keys:
 291          *   - host : The hostname of the DB server
 292          *   - user : The name of the database user the client operates under
 293          *   - password : The password for the database user
 294          *   - dbname : The name of the database to use where queries do not specify one.
 295          *      The database must exist or an error might be thrown. Setting this to the empty string
 296          *      will avoid any such errors and make the handle have no implicit database scope. This is
 297          *      useful for queries like SHOW STATUS, CREATE DATABASE, or DROP DATABASE. Note that a
 298          *      "database" in Postgres is rougly equivalent to an entire MySQL server. This the domain
 299          *      in which user names and such are defined, e.g. users are database-specific in Postgres.
 300          *   - schema : The database schema to use (if supported). A "schema" in Postgres is roughly
 301          *      equivalent to a "database" in MySQL. Note that MySQL and SQLite do not use schemas.
 302          *   - tablePrefix : Optional table prefix that is implicitly added on to all table names
 303          *      recognized in queries. This can be used in place of schemas for handle site farms.
 304          *   - flags : Optional bitfield of DBO_* constants that define connection, protocol,
 305          *      buffering, and transaction behavior. It is STRONGLY adviced to leave the DBO_DEFAULT
 306          *      flag in place UNLESS this this database simply acts as a key/value store.
 307          *   - driver: Optional name of a specific DB client driver. For MySQL, there is the old
 308          *      'mysql' driver and the newer 'mysqli' driver.
 309          *   - variables: Optional map of session variables to set after connecting. This can be
 310          *      used to adjust lock timeouts or encoding modes and the like.
 311          *   - connLogger: Optional PSR-3 logger interface instance.
 312          *   - queryLogger: Optional PSR-3 logger interface instance.
 313          *   - profiler: Optional class name or object with profileIn()/profileOut() methods.
 314          *      These will be called in query(), using a simplified version of the SQL that also
 315          *      includes the agent as a SQL comment.
 316          *   - trxProfiler: Optional TransactionProfiler instance.
 317          *   - errorLogger: Optional callback that takes an Exception and logs it.
 318          *   - cliMode: Whether to consider the execution context that of a CLI script.
 319          *   - agent: Optional name used to identify the end-user in query profiling/logging.
 320          *   - srvCache: Optional BagOStuff instance to an APC-style cache.
 321          * @return Database|null If the database driver or extension cannot be found
 322          * @throws InvalidArgumentException If the database driver or extension cannot be found
 323          * @since 1.18
 324          */
 325         final public static function factory( $dbType, $p = [] ) {
 326                 static $canonicalDBTypes = [
 327                         'mysql' => [ 'mysqli', 'mysql' ],
 328                         'postgres' => [],
 329                         'sqlite' => [],
 330                         'oracle' => [],
 331                         'mssql' => [],
 332                 ];
 333
 334                 $driver = false;
 335                 $dbType = strtolower( $dbType );
 336                 if ( isset( $canonicalDBTypes[$dbType] ) && $canonicalDBTypes[$dbType] ) {
 337                         $possibleDrivers = $canonicalDBTypes[$dbType];
 338                         if ( !empty( $p['driver'] ) ) {
 339                                 if ( in_array( $p['driver'], $possibleDrivers ) ) {
 340                                         $driver = $p['driver'];
 341                                 } else {
 342                                         throw new InvalidArgumentException( __METHOD__ .
 343                                                 " type '$dbType' does not support driver '{$p['driver']}'" );
 344                                 }
 345                         } else {
 346                                 foreach ( $possibleDrivers as $posDriver ) {
 347                                         if ( extension_loaded( $posDriver ) ) {
 348                                                 $driver = $posDriver;
 349                                                 break;
 350                                         }
 351                                 }
 352                         }
 353                 } else {
 354                         $driver = $dbType;
 355                 }
 356                 if ( $driver === false || $driver === '' ) {
 357                         throw new InvalidArgumentException( __METHOD__ .
 358                                 " no viable database extension found for type '$dbType'" );
 359                 }
 360
 361                 $class = 'Database' . ucfirst( $driver );
 362                 if ( class_exists( $class ) && is_subclass_of( $class, 'IDatabase' ) ) {
 363                         // Resolve some defaults for b/c
 364                         $p['host'] = isset( $p['host'] ) ? $p['host'] : false;
 365                         $p['user'] = isset( $p['user'] ) ? $p['user'] : false;
 366                         $p['password'] = isset( $p['password'] ) ? $p['password'] : false;
 367                         $p['dbname'] = isset( $p['dbname'] ) ? $p['dbname'] : false;
 368                         $p['flags'] = isset( $p['flags'] ) ? $p['flags'] : 0;
 369                         $p['variables'] = isset( $p['variables'] ) ? $p['variables'] : [];
 370                         $p['tablePrefix'] = isset( $p['tablePrefix'] ) ? $p['tablePrefix'] : '';
 371                         $p['schema'] = isset( $p['schema'] ) ? $p['schema'] : '';
 372                         $p['cliMode'] = isset( $p['cliMode'] ) ? $p['cliMode'] : ( PHP_SAPI === 'cli' );
 373                         $p['agent'] = isset( $p['agent'] ) ? $p['agent'] : '';
 374                         if ( !isset( $p['connLogger'] ) ) {
 375                                 $p['connLogger'] = new \Psr\Log\NullLogger();
 376                         }
 377                         if ( !isset( $p['queryLogger'] ) ) {
 378                                 $p['queryLogger'] = new \Psr\Log\NullLogger();
 379                         }
 380                         $p['profiler'] = isset( $p['profiler'] ) ? $p['profiler'] : null;
 381                         if ( !isset( $p['trxProfiler'] ) ) {
 382                                 $p['trxProfiler'] = new TransactionProfiler();
 383                         }
 384                         if ( !isset( $p['errorLogger'] ) ) {
 385                                 $p['errorLogger'] = function ( Exception $e ) {
 386                                         trigger_error( get_class( $e ) . ': ' . $e->getMessage(), E_WARNING );
 387                                 };
 388                         }
 389
 390                         $conn = new $class( $p );
 391                 } else {
 392                         $conn = null;
 393                 }
 394
 395                 return $conn;
 396         }
 397
 398         public function setLogger( LoggerInterface $logger ) {
 399                 $this->queryLogger = $logger;
 400         }
 401
 402         public function getServerInfo() {
 403                 return $this->getServerVersion();
 404         }
 405
 406         public function bufferResults( $buffer = null ) {
 407                 $res = !$this->getFlag( self::DBO_NOBUFFER );
 408                 if ( $buffer !== null ) {
 409                         $buffer
 410                                 ? $this->clearFlag( self::DBO_NOBUFFER )
 411                                 : $this->setFlag( self::DBO_NOBUFFER );
 412                 }
 413
 414                 return $res;
 415         }
 416
 417         /**
 418          * Turns on (false) or off (true) the automatic generation and sending
 419          * of a "we're sorry, but there has been a database error" page on
 420          * database errors. Default is on (false). When turned off, the
 421          * code should use lastErrno() and lastError() to handle the
 422          * situation as appropriate.
 423          *
 424          * Do not use this function outside of the Database classes.
 425          *
 426          * @param null|bool $ignoreErrors
 427          * @return bool The previous value of the flag.
 428          */
 429         protected function ignoreErrors( $ignoreErrors = null ) {
 430                 $res = $this->getFlag( self::DBO_IGNORE );
 431                 if ( $ignoreErrors !== null ) {
 432                         $ignoreErrors
 433                                 ? $this->setFlag( self::DBO_IGNORE )
 434                                 : $this->clearFlag( self::DBO_IGNORE );
 435                 }
 436
 437                 return $res;
 438         }
 439
 440         public function trxLevel() {
 441                 return $this->mTrxLevel;
 442         }
 443
 444         public function trxTimestamp() {
 445                 return $this->mTrxLevel ? $this->mTrxTimestamp : null;
 446         }
 447
 448         public function tablePrefix( $prefix = null ) {
 449                 $old = $this->mTablePrefix;
 450                 if ( $prefix !== null ) {
 451                         $this->mTablePrefix = $prefix;
 452                         $this->currentDomain = ( $this->mDBname != '' )
 453                                 ? new DatabaseDomain( $this->mDBname, null, $this->mTablePrefix )
 454                                 : DatabaseDomain::newUnspecified();
 455                 }
 456
 457                 return $old;
 458         }
 459
 460         public function dbSchema( $schema = null ) {
 461                 $old = $this->mSchema;
 462                 if ( $schema !== null ) {
 463                         $this->mSchema = $schema;
 464                 }
 465
 466                 return $old;
 467         }
 468
 469         public function getLBInfo( $name = null ) {
 470                 if ( is_null( $name ) ) {
 471                         return $this->mLBInfo;
 472                 } else {
 473                         if ( array_key_exists( $name, $this->mLBInfo ) ) {
 474                                 return $this->mLBInfo[$name];
 475                         } else {
 476                                 return null;
 477                         }
 478                 }
 479         }
 480
 481         public function setLBInfo( $name, $value = null ) {
 482                 if ( is_null( $value ) ) {
 483                         $this->mLBInfo = $name;
 484                 } else {
 485                         $this->mLBInfo[$name] = $value;
 486                 }
 487         }
 488
 489         public function setLazyMasterHandle( IDatabase $conn ) {
 490                 $this->lazyMasterHandle = $conn;
 491         }
 492
 493         /**
 494          * @return IDatabase|null
 495          * @see setLazyMasterHandle()
 496          * @since 1.27
 497          */
 498         protected function getLazyMasterHandle() {
 499                 return $this->lazyMasterHandle;
 500         }
 501
 502         public function implicitGroupby() {
 503                 return true;
 504         }
 505
 506         public function implicitOrderby() {
 507                 return true;
 508         }
 509
 510         public function lastQuery() {
 511                 return $this->mLastQuery;
 512         }
 513
 514         public function doneWrites() {
 515                 return (bool)$this->mLastWriteTime;
 516         }
 517
 518         public function lastDoneWrites() {
 519                 return $this->mLastWriteTime ?: false;
 520         }
 521
 522         public function writesPending() {
 523                 return $this->mTrxLevel && $this->mTrxDoneWrites;
 524         }
 525
 526         public function writesOrCallbacksPending() {
 527                 return $this->mTrxLevel && (
 528                         $this->mTrxDoneWrites || $this->mTrxIdleCallbacks || $this->mTrxPreCommitCallbacks
 529                 );
 530         }
 531
 532         public function pendingWriteQueryDuration( $type = self::ESTIMATE_TOTAL ) {
 533                 if ( !$this->mTrxLevel ) {
 534                         return false;
 535                 } elseif ( !$this->mTrxDoneWrites ) {
 536                         return 0.0;
 537                 }
 538
 539                 switch ( $type ) {
 540                         case self::ESTIMATE_DB_APPLY:
 541                                 $this->ping( $rtt );
 542                                 $rttAdjTotal = $this->mTrxWriteAdjQueryCount * $rtt;
 543                                 $applyTime = max( $this->mTrxWriteAdjDuration - $rttAdjTotal, 0 );
 544                                 // For omitted queries, make them count as something at least
 545                                 $omitted = $this->mTrxWriteQueryCount - $this->mTrxWriteAdjQueryCount;
 546                                 $applyTime += self::TINY_WRITE_SEC * $omitted;
 547
 548                                 return $applyTime;
 549                         default: // everything
 550                                 return $this->mTrxWriteDuration;
 551                 }
 552         }
 553
 554         public function pendingWriteCallers() {
 555                 return $this->mTrxLevel ? $this->mTrxWriteCallers : [];
 556         }
 557
 558         protected function pendingWriteAndCallbackCallers() {
 559                 if ( !$this->mTrxLevel ) {
 560                         return [];
 561                 }
 562
 563                 $fnames = $this->mTrxWriteCallers;
 564                 foreach ( [
 565                         $this->mTrxIdleCallbacks,
 566                         $this->mTrxPreCommitCallbacks,
 567                         $this->mTrxEndCallbacks
 568                 ] as $callbacks ) {
 569                         foreach ( $callbacks as $callback ) {
 570                                 $fnames[] = $callback[1];
 571                         }
 572                 }
 573
 574                 return $fnames;
 575         }
 576
 577         public function isOpen() {
 578                 return $this->mOpened;
 579         }
 580
 581         public function setFlag( $flag, $remember = self::REMEMBER_NOTHING ) {
 582                 if ( $remember === self::REMEMBER_PRIOR ) {
 583                         array_push( $this->priorFlags, $this->mFlags );
 584                 }
 585                 $this->mFlags |= $flag;
 586         }
 587
 588         public function clearFlag( $flag, $remember = self::REMEMBER_NOTHING ) {
 589                 if ( $remember === self::REMEMBER_PRIOR ) {
 590                         array_push( $this->priorFlags, $this->mFlags );
 591                 }
 592                 $this->mFlags &= ~$flag;
 593         }
 594
 595         public function restoreFlags( $state = self::RESTORE_PRIOR ) {
 596                 if ( !$this->priorFlags ) {
 597                         return;
 598                 }
 599
 600                 if ( $state === self::RESTORE_INITIAL ) {
 601                         $this->mFlags = reset( $this->priorFlags );
 602                         $this->priorFlags = [];
 603                 } else {
 604                         $this->mFlags = array_pop( $this->priorFlags );
 605                 }
 606         }
 607
 608         public function getFlag( $flag ) {
 609                 return !!( $this->mFlags & $flag );
 610         }
 611
 612         /**
 613          * @param string $name Class field name
 614          * @return mixed
 615          * @deprecated Since 1.28
 616          */
 617         public function getProperty( $name ) {
 618                 return $this->$name;
 619         }
 620
 621         public function getDomainID() {
 622                 return $this->currentDomain->getId();
 623         }
 624
 625         final public function getWikiID() {
 626                 return $this->getDomainID();
 627         }
 628
 629         /**
 630          * Get information about an index into an object
 631          * @param string $table Table name
 632          * @param string $index Index name
 633          * @param string $fname Calling function name
 634          * @return mixed Database-specific index description class or false if the index does not exist
 635          */
 636         abstract function indexInfo( $table, $index, $fname = __METHOD__ );
 637
 638         /**
 639          * Wrapper for addslashes()
 640          *
 641          * @param string $s String to be slashed.
 642          * @return string Slashed string.
 643          */
 644         abstract function strencode( $s );
 645
 646         protected function installErrorHandler() {
 647                 $this->mPHPError = false;
 648                 $this->htmlErrors = ini_set( 'html_errors', '0' );
 649                 set_error_handler( [ $this, 'connectionErrorLogger' ] );
 650         }
 651
 652         /**
 653          * @return bool|string
 654          */
 655         protected function restoreErrorHandler() {
 656                 restore_error_handler();
 657                 if ( $this->htmlErrors !== false ) {
 658                         ini_set( 'html_errors', $this->htmlErrors );
 659                 }
 660                 if ( $this->mPHPError ) {
 661                         $error = preg_replace( '!\[<a.*</a>\]!', '', $this->mPHPError );
 662                         $error = preg_replace( '!^.*?:\s?(.*)$!', '$1', $error );
 663
 664                         return $error;
 665                 } else {
 666                         return false;
 667                 }
 668         }
 669
 670         /**
 671          * This method should not be used outside of Database classes
 672          *
 673          * @param int $errno
 674          * @param string $errstr
 675          */
 676         public function connectionErrorLogger( $errno, $errstr ) {
 677                 $this->mPHPError = $errstr;
 678         }
 679
 680         /**
 681          * Create a log context to pass to PSR-3 logger functions.
 682          *
 683          * @param array $extras Additional data to add to context
 684          * @return array
 685          */
 686         protected function getLogContext( array $extras = [] ) {
 687                 return array_merge(
 688                         [
 689                                 'db_server' => $this->mServer,
 690                                 'db_name' => $this->mDBname,
 691                                 'db_user' => $this->mUser,
 692                         ],
 693                         $extras
 694                 );
 695         }
 696
 697         public function close() {
 698                 if ( $this->mConn ) {
 699                         if ( $this->trxLevel() ) {
 700                                 $this->commit( __METHOD__, self::FLUSHING_INTERNAL );
 701                         }
 702
 703                         $closed = $this->closeConnection();
 704                         $this->mConn = false;
 705                 } elseif ( $this->mTrxIdleCallbacks || $this->mTrxEndCallbacks ) { // sanity
 706                         throw new RuntimeException( "Transaction callbacks still pending." );
 707                 } else {
 708                         $closed = true;
 709                 }
 710                 $this->mOpened = false;
 711
 712                 return $closed;
 713         }
 714
 715         /**
 716          * Make sure isOpen() returns true as a sanity check
 717          *
 718          * @throws DBUnexpectedError
 719          */
 720         protected function assertOpen() {
 721                 if ( !$this->isOpen() ) {
 722                         throw new DBUnexpectedError( $this, "DB connection was already closed." );
 723                 }
 724         }
 725
 726         /**
 727          * Closes underlying database connection
 728          * @since 1.20
 729          * @return bool Whether connection was closed successfully
 730          */
 731         abstract protected function closeConnection();
 732
 733         public function reportConnectionError( $error = 'Unknown error' ) {
 734                 $myError = $this->lastError();
 735                 if ( $myError ) {
 736                         $error = $myError;
 737                 }
 738
 739                 # New method
 740                 throw new DBConnectionError( $this, $error );
 741         }
 742
 743         /**
 744          * The DBMS-dependent part of query()
 745          *
 746          * @param string $sql SQL query.
 747          * @return ResultWrapper|bool Result object to feed to fetchObject,
 748          *   fetchRow, ...; or false on failure
 749          */
 750         abstract protected function doQuery( $sql );
 751
 752         /**
 753          * Determine whether a query writes to the DB.
 754          * Should return true if unsure.
 755          *
 756          * @param string $sql
 757          * @return bool
 758          */
 759         protected function isWriteQuery( $sql ) {
 760                 return !preg_match(
 761                         '/^(?:SELECT|BEGIN|ROLLBACK|COMMIT|SET|SHOW|EXPLAIN|\(SELECT)\b/i', $sql );
 762         }
 763
 764         /**
 765          * @param $sql
 766          * @return string|null
 767          */
 768         protected function getQueryVerb( $sql ) {
 769                 return preg_match( '/^\s*([a-z]+)/i', $sql, $m ) ? strtoupper( $m[1] ) : null;
 770         }
 771
 772         /**
 773          * Determine whether a SQL statement is sensitive to isolation level.
 774          * A SQL statement is considered transactable if its result could vary
 775          * depending on the transaction isolation level. Operational commands
 776          * such as 'SET' and 'SHOW' are not considered to be transactable.
 777          *
 778          * @param string $sql
 779          * @return bool
 780          */
 781         protected function isTransactableQuery( $sql ) {
 782                 $verb = $this->getQueryVerb( $sql );
 783                 return !in_array( $verb, [ 'BEGIN', 'COMMIT', 'ROLLBACK', 'SHOW', 'SET' ], true );
 784         }
 785
 786         /**
 787          * @param string $sql A SQL query
 788          * @return bool Whether $sql is SQL for creating/dropping a new TEMPORARY table
 789          */
 790         protected function registerTempTableOperation( $sql ) {
 791                 if ( preg_match(
 792                         '/^CREATE\s+TEMPORARY\s+TABLE\s+(?:IF\s+NOT\s+EXISTS\s+)?[`"\']?(\w+)[`"\']?/i',
 793                         $sql,
 794                         $matches
 795                 ) ) {
 796                         $this->mSessionTempTables[$matches[1]] = 1;
 797
 798                         return true;
 799                 } elseif ( preg_match(
 800                         '/^DROP\s+(?:TEMPORARY\s+)?TABLE\s+(?:IF\s+EXISTS\s+)?[`"\']?(\w+)[`"\']?/i',
 801                         $sql,
 802                         $matches
 803                 ) ) {
 804                         unset( $this->mSessionTempTables[$matches[1]] );
 805
 806                         return true;
 807                 } elseif ( preg_match(
 808                         '/^(?:INSERT\s+(?:\w+\s+)?INTO|UPDATE|DELETE\s+FROM)\s+[`"\']?(\w+)[`"\']?/i',
 809                         $sql,
 810                         $matches
 811                 ) ) {
 812                         return isset( $this->mSessionTempTables[$matches[1]] );
 813                 }
 814
 815                 return false;
 816         }
 817
 818         public function query( $sql, $fname = __METHOD__, $tempIgnore = false ) {
 819                 $priorWritesPending = $this->writesOrCallbacksPending();
 820                 $this->mLastQuery = $sql;
 821
 822                 $isWrite = $this->isWriteQuery( $sql ) && !$this->registerTempTableOperation( $sql );
 823                 if ( $isWrite ) {
 824                         $reason = $this->getReadOnlyReason();
 825                         if ( $reason !== false ) {
 826                                 throw new DBReadOnlyError( $this, "Database is read-only: $reason" );
 827                         }
 828                         # Set a flag indicating that writes have been done
 829                         $this->mLastWriteTime = microtime( true );
 830                 }
 831
 832                 // Add trace comment to the begin of the sql string, right after the operator.
 833                 // Or, for one-word queries (like "BEGIN" or COMMIT") add it to the end (bug 42598)
 834                 $commentedSql = preg_replace( '/\s|$/', " /* $fname {$this->agent} */ ", $sql, 1 );
 835
 836                 # Start implicit transactions that wrap the request if DBO_TRX is enabled
 837                 if ( !$this->mTrxLevel && $this->getFlag( self::DBO_TRX )
 838                         && $this->isTransactableQuery( $sql )
 839                 ) {
 840                         $this->begin( __METHOD__ . " ($fname)", self::TRANSACTION_INTERNAL );
 841                         $this->mTrxAutomatic = true;
 842                 }
 843
 844                 # Keep track of whether the transaction has write queries pending
 845                 if ( $this->mTrxLevel && !$this->mTrxDoneWrites && $isWrite ) {
 846                         $this->mTrxDoneWrites = true;
 847                         $this->trxProfiler->transactionWritingIn(
 848                                 $this->mServer, $this->mDBname, $this->mTrxShortId );
 849                 }
 850
 851                 if ( $this->getFlag( self::DBO_DEBUG ) ) {
 852                         $this->queryLogger->debug( "{$this->mDBname} {$commentedSql}" );
 853                 }
 854
 855                 # Avoid fatals if close() was called
 856                 $this->assertOpen();
 857
 858                 # Send the query to the server
 859                 $ret = $this->doProfiledQuery( $sql, $commentedSql, $isWrite, $fname );
 860
 861                 # Try reconnecting if the connection was lost
 862                 if ( false === $ret && $this->wasErrorReissuable() ) {
 863                         $recoverable = $this->canRecoverFromDisconnect( $sql, $priorWritesPending );
 864                         # Stash the last error values before anything might clear them
 865                         $lastError = $this->lastError();
 866                         $lastErrno = $this->lastErrno();
 867                         # Update state tracking to reflect transaction loss due to disconnection
 868                         $this->handleSessionLoss();
 869                         if ( $this->reconnect() ) {
 870                                 $msg = __METHOD__ . ": lost connection to {$this->getServer()}; reconnected";
 871                                 $this->connLogger->warning( $msg );
 872                                 $this->queryLogger->warning(
 873                                         "$msg:\n" . ( new RuntimeException() )->getTraceAsString() );
 874
 875                                 if ( !$recoverable ) {
 876                                         # Callers may catch the exception and continue to use the DB
 877                                         $this->reportQueryError( $lastError, $lastErrno, $sql, $fname );
 878                                 } else {
 879                                         # Should be safe to silently retry the query
 880                                         $ret = $this->doProfiledQuery( $sql, $commentedSql, $isWrite, $fname );
 881                                 }
 882                         } else {
 883                                 $msg = __METHOD__ . ": lost connection to {$this->getServer()} permanently";
 884                                 $this->connLogger->error( $msg );
 885                         }
 886                 }
 887
 888                 if ( false === $ret ) {
 889                         # Deadlocks cause the entire transaction to abort, not just the statement.
 890                         # http://dev.mysql.com/doc/refman/5.7/en/innodb-error-handling.html
 891                         # https://www.postgresql.org/docs/9.1/static/explicit-locking.html
 892                         if ( $this->wasDeadlock() ) {
 893                                 if ( $this->explicitTrxActive() || $priorWritesPending ) {
 894                                         $tempIgnore = false; // not recoverable
 895                                 }
 896                                 # Update state tracking to reflect transaction loss
 897                                 $this->handleSessionLoss();
 898                         }
 899
 900                         $this->reportQueryError(
 901                                 $this->lastError(), $this->lastErrno(), $sql, $fname, $tempIgnore );
 902                 }
 903
 904                 $res = $this->resultObject( $ret );
 905
 906                 return $res;
 907         }
 908
 909         private function doProfiledQuery( $sql, $commentedSql, $isWrite, $fname ) {
 910                 $isMaster = !is_null( $this->getLBInfo( 'master' ) );
 911                 # generalizeSQL() will probably cut down the query to reasonable
 912                 # logging size most of the time. The substr is really just a sanity check.
 913                 if ( $isMaster ) {
 914                         $queryProf = 'query-m: ' . substr( self::generalizeSQL( $sql ), 0, 255 );
 915                 } else {
 916                         $queryProf = 'query: ' . substr( self::generalizeSQL( $sql ), 0, 255 );
 917                 }
 918
 919                 # Include query transaction state
 920                 $queryProf .= $this->mTrxShortId ? " [TRX#{$this->mTrxShortId}]" : "";
 921
 922                 $startTime = microtime( true );
 923                 if ( $this->profiler ) {
 924                         call_user_func( [ $this->profiler, 'profileIn' ], $queryProf );
 925                 }
 926                 $ret = $this->doQuery( $commentedSql );
 927                 if ( $this->profiler ) {
 928                         call_user_func( [ $this->profiler, 'profileOut' ], $queryProf );
 929                 }
 930                 $queryRuntime = max( microtime( true ) - $startTime, 0.0 );
 931
 932                 unset( $queryProfSection ); // profile out (if set)
 933
 934                 if ( $ret !== false ) {
 935                         $this->lastPing = $startTime;
 936                         if ( $isWrite && $this->mTrxLevel ) {
 937                                 $this->updateTrxWriteQueryTime( $sql, $queryRuntime );
 938                                 $this->mTrxWriteCallers[] = $fname;
 939                         }
 940                 }
 941
 942                 if ( $sql === self::PING_QUERY ) {
 943                         $this->mRTTEstimate = $queryRuntime;
 944                 }
 945
 946                 $this->trxProfiler->recordQueryCompletion(
 947                         $queryProf, $startTime, $isWrite, $this->affectedRows()
 948                 );
 949                 $this->queryLogger->debug( $sql, [
 950                         'method' => $fname,
 951                         'master' => $isMaster,
 952                         'runtime' => $queryRuntime,
 953                 ] );
 954
 955                 return $ret;
 956         }
 957
 958         /**
 959          * Update the estimated run-time of a query, not counting large row lock times
 960          *
 961          * LoadBalancer can be set to rollback transactions that will create huge replication
 962          * lag. It bases this estimate off of pendingWriteQueryDuration(). Certain simple
 963          * queries, like inserting a row can take a long time due to row locking. This method
 964          * uses some simple heuristics to discount those cases.
 965          *
 966          * @param string $sql A SQL write query
 967          * @param float $runtime Total runtime, including RTT
 968          */
 969         private function updateTrxWriteQueryTime( $sql, $runtime ) {
 970                 // Whether this is indicative of replica DB runtime (except for RBR or ws_repl)
 971                 $indicativeOfReplicaRuntime = true;
 972                 if ( $runtime > self::SLOW_WRITE_SEC ) {
 973                         $verb = $this->getQueryVerb( $sql );
 974                         // insert(), upsert(), replace() are fast unless bulky in size or blocked on locks
 975                         if ( $verb === 'INSERT' ) {
 976                                 $indicativeOfReplicaRuntime = $this->affectedRows() > self::SMALL_WRITE_ROWS;
 977                         } elseif ( $verb === 'REPLACE' ) {
 978                                 $indicativeOfReplicaRuntime = $this->affectedRows() > self::SMALL_WRITE_ROWS / 2;
 979                         }
 980                 }
 981
 982                 $this->mTrxWriteDuration += $runtime;
 983                 $this->mTrxWriteQueryCount += 1;
 984                 if ( $indicativeOfReplicaRuntime ) {
 985                         $this->mTrxWriteAdjDuration += $runtime;
 986                         $this->mTrxWriteAdjQueryCount += 1;
 987                 }
 988         }
 989
 990         private function canRecoverFromDisconnect( $sql, $priorWritesPending ) {
 991                 # Transaction dropped; this can mean lost writes, or REPEATABLE-READ snapshots.
 992                 # Dropped connections also mean that named locks are automatically released.
 993                 # Only allow error suppression in autocommit mode or when the lost transaction
 994                 # didn't matter anyway (aside from DBO_TRX snapshot loss).
 995                 if ( $this->mNamedLocksHeld ) {
 996                         return false; // possible critical section violation
 997                 } elseif ( $sql === 'COMMIT' ) {
 998                         return !$priorWritesPending; // nothing written anyway? (T127428)
 999                 } elseif ( $sql === 'ROLLBACK' ) {
1000                         return true; // transaction lost...which is also what was requested :)
1001                 } elseif ( $this->explicitTrxActive() ) {
1002                         return false; // don't drop atomocity
1003                 } elseif ( $priorWritesPending ) {
1004                         return false; // prior writes lost from implicit transaction
1005                 }
1006
1007                 return true;
1008         }
1009
1010         private function handleSessionLoss() {
1011                 $this->mTrxLevel = 0;
1012                 $this->mTrxIdleCallbacks = []; // bug 65263
1013                 $this->mTrxPreCommitCallbacks = []; // bug 65263
1014                 $this->mSessionTempTables = [];
1015                 $this->mNamedLocksHeld = [];
1016                 try {
1017                         // Handle callbacks in mTrxEndCallbacks
1018                         $this->runOnTransactionIdleCallbacks( self::TRIGGER_ROLLBACK );
1019                         $this->runTransactionListenerCallbacks( self::TRIGGER_ROLLBACK );
1020                         return null;
1021                 } catch ( Exception $e ) {
1022                         // Already logged; move on...
1023                         return $e;
1024                 }
1025         }
1026
1027         public function reportQueryError( $error, $errno, $sql, $fname, $tempIgnore = false ) {
1028                 if ( $this->ignoreErrors() || $tempIgnore ) {
1029                         $this->queryLogger->debug( "SQL ERROR (ignored): $error\n" );
1030                 } else {
1031                         $sql1line = mb_substr( str_replace( "\n", "\\n", $sql ), 0, 5 * 1024 );
1032                         $this->queryLogger->error(
1033                                 "{fname}\t{db_server}\t{errno}\t{error}\t{sql1line}",
1034                                 $this->getLogContext( [
1035                                         'method' => __METHOD__,
1036                                         'errno' => $errno,
1037                                         'error' => $error,
1038                                         'sql1line' => $sql1line,
1039                                         'fname' => $fname,
1040                                 ] )
1041                         );
1042                         $this->queryLogger->debug( "SQL ERROR: " . $error . "\n" );
1043                         throw new DBQueryError( $this, $error, $errno, $sql, $fname );
1044                 }
1045         }
1046
1047         public function freeResult( $res ) {
1048         }
1049
1050         public function selectField(
1051                 $table, $var, $cond = '', $fname = __METHOD__, $options = []
1052         ) {
1053                 if ( $var === '*' ) { // sanity
1054                         throw new DBUnexpectedError( $this, "Cannot use a * field: got '$var'" );
1055                 }
1056
1057                 if ( !is_array( $options ) ) {
1058                         $options = [ $options ];
1059                 }
1060
1061                 $options['LIMIT'] = 1;
1062
1063                 $res = $this->select( $table, $var, $cond, $fname, $options );
1064                 if ( $res === false || !$this->numRows( $res ) ) {
1065                         return false;
1066                 }
1067
1068                 $row = $this->fetchRow( $res );
1069
1070                 if ( $row !== false ) {
1071                         return reset( $row );
1072                 } else {
1073                         return false;
1074                 }
1075         }
1076
1077         public function selectFieldValues(
1078                 $table, $var, $cond = '', $fname = __METHOD__, $options = [], $join_conds = []
1079         ) {
1080                 if ( $var === '*' ) { // sanity
1081                         throw new DBUnexpectedError( $this, "Cannot use a * field" );
1082                 } elseif ( !is_string( $var ) ) { // sanity
1083                         throw new DBUnexpectedError( $this, "Cannot use an array of fields" );
1084                 }
1085
1086                 if ( !is_array( $options ) ) {
1087                         $options = [ $options ];
1088                 }
1089
1090                 $res = $this->select( $table, $var, $cond, $fname, $options, $join_conds );
1091                 if ( $res === false ) {
1092                         return false;
1093                 }
1094
1095                 $values = [];
1096                 foreach ( $res as $row ) {
1097                         $values[] = $row->$var;
1098                 }
1099
1100                 return $values;
1101         }
1102
1103         /**
1104          * Returns an optional USE INDEX clause to go after the table, and a
1105          * string to go at the end of the query.
1106          *
1107          * @param array $options Associative array of options to be turned into
1108          *   an SQL query, valid keys are listed in the function.
1109          * @return array
1110          * @see Database::select()
1111          */
1112         protected function makeSelectOptions( $options ) {
1113                 $preLimitTail = $postLimitTail = '';
1114                 $startOpts = '';
1115
1116                 $noKeyOptions = [];
1117
1118                 foreach ( $options as $key => $option ) {
1119                         if ( is_numeric( $key ) ) {
1120                                 $noKeyOptions[$option] = true;
1121                         }
1122                 }
1123
1124                 $preLimitTail .= $this->makeGroupByWithHaving( $options );
1125
1126                 $preLimitTail .= $this->makeOrderBy( $options );
1127
1128                 // if (isset($options['LIMIT'])) {
1129                 //      $tailOpts .= $this->limitResult('', $options['LIMIT'],
1130                 //              isset($options['OFFSET']) ? $options['OFFSET']
1131                 //              : false);
1132                 // }
1133
1134                 if ( isset( $noKeyOptions['FOR UPDATE'] ) ) {
1135                         $postLimitTail .= ' FOR UPDATE';
1136                 }
1137
1138                 if ( isset( $noKeyOptions['LOCK IN SHARE MODE'] ) ) {
1139                         $postLimitTail .= ' LOCK IN SHARE MODE';
1140                 }
1141
1142                 if ( isset( $noKeyOptions['DISTINCT'] ) || isset( $noKeyOptions['DISTINCTROW'] ) ) {
1143                         $startOpts .= 'DISTINCT';
1144                 }
1145
1146                 # Various MySQL extensions
1147                 if ( isset( $noKeyOptions['STRAIGHT_JOIN'] ) ) {
1148                         $startOpts .= ' /*! STRAIGHT_JOIN */';
1149                 }
1150
1151                 if ( isset( $noKeyOptions['HIGH_PRIORITY'] ) ) {
1152                         $startOpts .= ' HIGH_PRIORITY';
1153                 }
1154
1155                 if ( isset( $noKeyOptions['SQL_BIG_RESULT'] ) ) {
1156                         $startOpts .= ' SQL_BIG_RESULT';
1157                 }
1158
1159                 if ( isset( $noKeyOptions['SQL_BUFFER_RESULT'] ) ) {
1160                         $startOpts .= ' SQL_BUFFER_RESULT';
1161                 }
1162
1163                 if ( isset( $noKeyOptions['SQL_SMALL_RESULT'] ) ) {
1164                         $startOpts .= ' SQL_SMALL_RESULT';
1165                 }
1166
1167                 if ( isset( $noKeyOptions['SQL_CALC_FOUND_ROWS'] ) ) {
1168                         $startOpts .= ' SQL_CALC_FOUND_ROWS';
1169                 }
1170
1171                 if ( isset( $noKeyOptions['SQL_CACHE'] ) ) {
1172                         $startOpts .= ' SQL_CACHE';
1173                 }
1174
1175                 if ( isset( $noKeyOptions['SQL_NO_CACHE'] ) ) {
1176                         $startOpts .= ' SQL_NO_CACHE';
1177                 }
1178
1179                 if ( isset( $options['USE INDEX'] ) && is_string( $options['USE INDEX'] ) ) {
1180                         $useIndex = $this->useIndexClause( $options['USE INDEX'] );
1181                 } else {
1182                         $useIndex = '';
1183                 }
1184                 if ( isset( $options['IGNORE INDEX'] ) && is_string( $options['IGNORE INDEX'] ) ) {
1185                         $ignoreIndex = $this->ignoreIndexClause( $options['IGNORE INDEX'] );
1186                 } else {
1187                         $ignoreIndex = '';
1188                 }
1189
1190                 return [ $startOpts, $useIndex, $preLimitTail, $postLimitTail, $ignoreIndex ];
1191         }
1192
1193         /**
1194          * Returns an optional GROUP BY with an optional HAVING
1195          *
1196          * @param array $options Associative array of options
1197          * @return string
1198          * @see Database::select()
1199          * @since 1.21
1200          */
1201         protected function makeGroupByWithHaving( $options ) {
1202                 $sql = '';
1203                 if ( isset( $options['GROUP BY'] ) ) {
1204                         $gb = is_array( $options['GROUP BY'] )
1205                                 ? implode( ',', $options['GROUP BY'] )
1206                                 : $options['GROUP BY'];
1207                         $sql .= ' GROUP BY ' . $gb;
1208                 }
1209                 if ( isset( $options['HAVING'] ) ) {
1210                         $having = is_array( $options['HAVING'] )
1211                                 ? $this->makeList( $options['HAVING'], self::LIST_AND )
1212                                 : $options['HAVING'];
1213                         $sql .= ' HAVING ' . $having;
1214                 }
1215
1216                 return $sql;
1217         }
1218
1219         /**
1220          * Returns an optional ORDER BY
1221          *
1222          * @param array $options Associative array of options
1223          * @return string
1224          * @see Database::select()
1225          * @since 1.21
1226          */
1227         protected function makeOrderBy( $options ) {
1228                 if ( isset( $options['ORDER BY'] ) ) {
1229                         $ob = is_array( $options['ORDER BY'] )
1230                                 ? implode( ',', $options['ORDER BY'] )
1231                                 : $options['ORDER BY'];
1232
1233                         return ' ORDER BY ' . $ob;
1234                 }
1235
1236                 return '';
1237         }
1238
1239         public function select( $table, $vars, $conds = '', $fname = __METHOD__,
1240                 $options = [], $join_conds = [] ) {
1241                 $sql = $this->selectSQLText( $table, $vars, $conds, $fname, $options, $join_conds );
1242
1243                 return $this->query( $sql, $fname );
1244         }
1245
1246         public function selectSQLText( $table, $vars, $conds = '', $fname = __METHOD__,
1247                 $options = [], $join_conds = []
1248         ) {
1249                 if ( is_array( $vars ) ) {
1250                         $vars = implode( ',', $this->fieldNamesWithAlias( $vars ) );
1251                 }
1252
1253                 $options = (array)$options;
1254                 $useIndexes = ( isset( $options['USE INDEX'] ) && is_array( $options['USE INDEX'] ) )
1255                         ? $options['USE INDEX']
1256                         : [];
1257                 $ignoreIndexes = (
1258                         isset( $options['IGNORE INDEX'] ) &&
1259                         is_array( $options['IGNORE INDEX'] )
1260                 )
1261                         ? $options['IGNORE INDEX']
1262                         : [];
1263
1264                 if ( is_array( $table ) ) {
1265                         $from = ' FROM ' .
1266                                 $this->tableNamesWithIndexClauseOrJOIN(
1267                                         $table, $useIndexes, $ignoreIndexes, $join_conds );
1268                 } elseif ( $table != '' ) {
1269                         if ( $table[0] == ' ' ) {
1270                                 $from = ' FROM ' . $table;
1271                         } else {
1272                                 $from = ' FROM ' .
1273                                         $this->tableNamesWithIndexClauseOrJOIN(
1274                                                 [ $table ], $useIndexes, $ignoreIndexes, [] );
1275                         }
1276                 } else {
1277                         $from = '';
1278                 }
1279
1280                 list( $startOpts, $useIndex, $preLimitTail, $postLimitTail, $ignoreIndex ) =
1281                         $this->makeSelectOptions( $options );
1282
1283                 if ( !empty( $conds ) ) {
1284                         if ( is_array( $conds ) ) {
1285                                 $conds = $this->makeList( $conds, self::LIST_AND );
1286                         }
1287                         $sql = "SELECT $startOpts $vars $from $useIndex $ignoreIndex " .
1288                                 "WHERE $conds $preLimitTail";
1289                 } else {
1290                         $sql = "SELECT $startOpts $vars $from $useIndex $ignoreIndex $preLimitTail";
1291                 }
1292
1293                 if ( isset( $options['LIMIT'] ) ) {
1294                         $sql = $this->limitResult( $sql, $options['LIMIT'],
1295                                 isset( $options['OFFSET'] ) ? $options['OFFSET'] : false );
1296                 }
1297                 $sql = "$sql $postLimitTail";
1298
1299                 if ( isset( $options['EXPLAIN'] ) ) {
1300                         $sql = 'EXPLAIN ' . $sql;
1301                 }
1302
1303                 return $sql;
1304         }
1305
1306         public function selectRow( $table, $vars, $conds, $fname = __METHOD__,
1307                 $options = [], $join_conds = []
1308         ) {
1309                 $options = (array)$options;
1310                 $options['LIMIT'] = 1;
1311                 $res = $this->select( $table, $vars, $conds, $fname, $options, $join_conds );
1312
1313                 if ( $res === false ) {
1314                         return false;
1315                 }
1316
1317                 if ( !$this->numRows( $res ) ) {
1318                         return false;
1319                 }
1320
1321                 $obj = $this->fetchObject( $res );
1322
1323                 return $obj;
1324         }
1325
1326         public function estimateRowCount(
1327                 $table, $vars = '*', $conds = '', $fname = __METHOD__, $options = []
1328         ) {
1329                 $rows = 0;
1330                 $res = $this->select( $table, [ 'rowcount' => 'COUNT(*)' ], $conds, $fname, $options );
1331
1332                 if ( $res ) {
1333                         $row = $this->fetchRow( $res );
1334                         $rows = ( isset( $row['rowcount'] ) ) ? (int)$row['rowcount'] : 0;
1335                 }
1336
1337                 return $rows;
1338         }
1339
1340         public function selectRowCount(
1341                 $tables, $vars = '*', $conds = '', $fname = __METHOD__, $options = [], $join_conds = []
1342         ) {
1343                 $rows = 0;
1344                 $sql = $this->selectSQLText( $tables, '1', $conds, $fname, $options, $join_conds );
1345                 $res = $this->query( "SELECT COUNT(*) AS rowcount FROM ($sql) tmp_count", $fname );
1346
1347                 if ( $res ) {
1348                         $row = $this->fetchRow( $res );
1349                         $rows = ( isset( $row['rowcount'] ) ) ? (int)$row['rowcount'] : 0;
1350                 }
1351
1352                 return $rows;
1353         }
1354
1355         /**
1356          * Removes most variables from an SQL query and replaces them with X or N for numbers.
1357          * It's only slightly flawed. Don't use for anything important.
1358          *
1359          * @param string $sql A SQL Query
1360          *
1361          * @return string
1362          */
1363         protected static function generalizeSQL( $sql ) {
1364                 # This does the same as the regexp below would do, but in such a way
1365                 # as to avoid crashing php on some large strings.
1366                 # $sql = preg_replace( "/'([^\\\\']|\\\\.)*'|\"([^\\\\\"]|\\\\.)*\"/", "'X'", $sql );
1367
1368                 $sql = str_replace( "\\\\", '', $sql );
1369                 $sql = str_replace( "\\'", '', $sql );
1370                 $sql = str_replace( "\\\"", '', $sql );
1371                 $sql = preg_replace( "/'.*'/s", "'X'", $sql );
1372                 $sql = preg_replace( '/".*"/s', "'X'", $sql );
1373
1374                 # All newlines, tabs, etc replaced by single space
1375                 $sql = preg_replace( '/\s+/', ' ', $sql );
1376
1377                 # All numbers => N,
1378                 # except the ones surrounded by characters, e.g. l10n
1379                 $sql = preg_replace( '/-?\d+(,-?\d+)+/s', 'N,...,N', $sql );
1380                 $sql = preg_replace( '/(?<![a-zA-Z])-?\d+(?![a-zA-Z])/s', 'N', $sql );
1381
1382                 return $sql;
1383         }
1384
1385         public function fieldExists( $table, $field, $fname = __METHOD__ ) {
1386                 $info = $this->fieldInfo( $table, $field );
1387
1388                 return (bool)$info;
1389         }
1390
1391         public function indexExists( $table, $index, $fname = __METHOD__ ) {
1392                 if ( !$this->tableExists( $table ) ) {
1393                         return null;
1394                 }
1395
1396                 $info = $this->indexInfo( $table, $index, $fname );
1397                 if ( is_null( $info ) ) {
1398                         return null;
1399                 } else {
1400                         return $info !== false;
1401                 }
1402         }
1403
1404         public function tableExists( $table, $fname = __METHOD__ ) {
1405                 $tableRaw = $this->tableName( $table, 'raw' );
1406                 if ( isset( $this->mSessionTempTables[$tableRaw] ) ) {
1407                         return true; // already known to exist
1408                 }
1409
1410                 $table = $this->tableName( $table );
1411                 $old = $this->ignoreErrors( true );
1412                 $res = $this->query( "SELECT 1 FROM $table LIMIT 1", $fname );
1413                 $this->ignoreErrors( $old );
1414
1415                 return (bool)$res;
1416         }
1417
1418         public function indexUnique( $table, $index ) {
1419                 $indexInfo = $this->indexInfo( $table, $index );
1420
1421                 if ( !$indexInfo ) {
1422                         return null;
1423                 }
1424
1425                 return !$indexInfo[0]->Non_unique;
1426         }
1427
1428         /**
1429          * Helper for Database::insert().
1430          *
1431          * @param array $options
1432          * @return string
1433          */
1434         protected function makeInsertOptions( $options ) {
1435                 return implode( ' ', $options );
1436         }
1437
1438         public function insert( $table, $a, $fname = __METHOD__, $options = [] ) {
1439                 # No rows to insert, easy just return now
1440                 if ( !count( $a ) ) {
1441                         return true;
1442                 }
1443
1444                 $table = $this->tableName( $table );
1445
1446                 if ( !is_array( $options ) ) {
1447                         $options = [ $options ];
1448                 }
1449
1450                 $fh = null;
1451                 if ( isset( $options['fileHandle'] ) ) {
1452                         $fh = $options['fileHandle'];
1453                 }
1454                 $options = $this->makeInsertOptions( $options );
1455
1456                 if ( isset( $a[0] ) && is_array( $a[0] ) ) {
1457                         $multi = true;
1458                         $keys = array_keys( $a[0] );
1459                 } else {
1460                         $multi = false;
1461                         $keys = array_keys( $a );
1462                 }
1463
1464                 $sql = 'INSERT ' . $options .
1465                         " INTO $table (" . implode( ',', $keys ) . ') VALUES ';
1466
1467                 if ( $multi ) {
1468                         $first = true;
1469                         foreach ( $a as $row ) {
1470                                 if ( $first ) {
1471                                         $first = false;
1472                                 } else {
1473                                         $sql .= ',';
1474                                 }
1475                                 $sql .= '(' . $this->makeList( $row ) . ')';
1476                         }
1477                 } else {
1478                         $sql .= '(' . $this->makeList( $a ) . ')';
1479                 }
1480
1481                 if ( $fh !== null && false === fwrite( $fh, $sql ) ) {
1482                         return false;
1483                 } elseif ( $fh !== null ) {
1484                         return true;
1485                 }
1486
1487                 return (bool)$this->query( $sql, $fname );
1488         }
1489
1490         /**
1491          * Make UPDATE options array for Database::makeUpdateOptions
1492          *
1493          * @param array $options
1494          * @return array
1495          */
1496         protected function makeUpdateOptionsArray( $options ) {
1497                 if ( !is_array( $options ) ) {
1498                         $options = [ $options ];
1499                 }
1500
1501                 $opts = [];
1502
1503                 if ( in_array( 'IGNORE', $options ) ) {
1504                         $opts[] = 'IGNORE';
1505                 }
1506
1507                 return $opts;
1508         }
1509
1510         /**
1511          * Make UPDATE options for the Database::update function
1512          *
1513          * @param array $options The options passed to Database::update
1514          * @return string
1515          */
1516         protected function makeUpdateOptions( $options ) {
1517                 $opts = $this->makeUpdateOptionsArray( $options );
1518
1519                 return implode( ' ', $opts );
1520         }
1521
1522         public function update( $table, $values, $conds, $fname = __METHOD__, $options = [] ) {
1523                 $table = $this->tableName( $table );
1524                 $opts = $this->makeUpdateOptions( $options );
1525                 $sql = "UPDATE $opts $table SET " . $this->makeList( $values, self::LIST_SET );
1526
1527                 if ( $conds !== [] && $conds !== '*' ) {
1528                         $sql .= " WHERE " . $this->makeList( $conds, self::LIST_AND );
1529                 }
1530
1531                 return $this->query( $sql, $fname );
1532         }
1533
1534         public function makeList( $a, $mode = self::LIST_COMMA ) {
1535                 if ( !is_array( $a ) ) {
1536                         throw new DBUnexpectedError( $this, __METHOD__ . ' called with incorrect parameters' );
1537                 }
1538
1539                 $first = true;
1540                 $list = '';
1541
1542                 foreach ( $a as $field => $value ) {
1543                         if ( !$first ) {
1544                                 if ( $mode == self::LIST_AND ) {
1545                                         $list .= ' AND ';
1546                                 } elseif ( $mode == self::LIST_OR ) {
1547                                         $list .= ' OR ';
1548                                 } else {
1549                                         $list .= ',';
1550                                 }
1551                         } else {
1552                                 $first = false;
1553                         }
1554
1555                         if ( ( $mode == self::LIST_AND || $mode == self::LIST_OR ) && is_numeric( $field ) ) {
1556                                 $list .= "($value)";
1557                         } elseif ( $mode == self::LIST_SET && is_numeric( $field ) ) {
1558                                 $list .= "$value";
1559                         } elseif (
1560                                 ( $mode == self::LIST_AND || $mode == self::LIST_OR ) && is_array( $value )
1561                         ) {
1562                                 // Remove null from array to be handled separately if found
1563                                 $includeNull = false;
1564                                 foreach ( array_keys( $value, null, true ) as $nullKey ) {
1565                                         $includeNull = true;
1566                                         unset( $value[$nullKey] );
1567                                 }
1568                                 if ( count( $value ) == 0 && !$includeNull ) {
1569                                         throw new InvalidArgumentException(
1570                                                 __METHOD__ . ": empty input for field $field" );
1571                                 } elseif ( count( $value ) == 0 ) {
1572                                         // only check if $field is null
1573                                         $list .= "$field IS NULL";
1574                                 } else {
1575                                         // IN clause contains at least one valid element
1576                                         if ( $includeNull ) {
1577                                                 // Group subconditions to ensure correct precedence
1578                                                 $list .= '(';
1579                                         }
1580                                         if ( count( $value ) == 1 ) {
1581                                                 // Special-case single values, as IN isn't terribly efficient
1582                                                 // Don't necessarily assume the single key is 0; we don't
1583                                                 // enforce linear numeric ordering on other arrays here.
1584                                                 $value = array_values( $value )[0];
1585                                                 $list .= $field . " = " . $this->addQuotes( $value );
1586                                         } else {
1587                                                 $list .= $field . " IN (" . $this->makeList( $value ) . ") ";
1588                                         }
1589                                         // if null present in array, append IS NULL
1590                                         if ( $includeNull ) {
1591                                                 $list .= " OR $field IS NULL)";
1592                                         }
1593                                 }
1594                         } elseif ( $value === null ) {
1595                                 if ( $mode == self::LIST_AND || $mode == self::LIST_OR ) {
1596                                         $list .= "$field IS ";
1597                                 } elseif ( $mode == self::LIST_SET ) {
1598                                         $list .= "$field = ";
1599                                 }
1600                                 $list .= 'NULL';
1601                         } else {
1602                                 if (
1603                                         $mode == self::LIST_AND || $mode == self::LIST_OR || $mode == self::LIST_SET
1604                                 ) {
1605                                         $list .= "$field = ";
1606                                 }
1607                                 $list .= $mode == self::LIST_NAMES ? $value : $this->addQuotes( $value );
1608                         }
1609                 }
1610
1611                 return $list;
1612         }
1613
1614         public function makeWhereFrom2d( $data, $baseKey, $subKey ) {
1615                 $conds = [];
1616
1617                 foreach ( $data as $base => $sub ) {
1618                         if ( count( $sub ) ) {
1619                                 $conds[] = $this->makeList(
1620                                         [ $baseKey => $base, $subKey => array_keys( $sub ) ],
1621                                         self::LIST_AND );
1622                         }
1623                 }
1624
1625                 if ( $conds ) {
1626                         return $this->makeList( $conds, self::LIST_OR );
1627                 } else {
1628                         // Nothing to search for...
1629                         return false;
1630                 }
1631         }
1632
1633         public function aggregateValue( $valuedata, $valuename = 'value' ) {
1634                 return $valuename;
1635         }
1636
1637         public function bitNot( $field ) {
1638                 return "(~$field)";
1639         }
1640
1641         public function bitAnd( $fieldLeft, $fieldRight ) {
1642                 return "($fieldLeft & $fieldRight)";
1643         }
1644
1645         public function bitOr( $fieldLeft, $fieldRight ) {
1646                 return "($fieldLeft | $fieldRight)";
1647         }
1648
1649         public function buildConcat( $stringList ) {
1650                 return 'CONCAT(' . implode( ',', $stringList ) . ')';
1651         }
1652
1653         public function buildGroupConcatField(
1654                 $delim, $table, $field, $conds = '', $join_conds = []
1655         ) {
1656                 $fld = "GROUP_CONCAT($field SEPARATOR " . $this->addQuotes( $delim ) . ')';
1657
1658                 return '(' . $this->selectSQLText( $table, $fld, $conds, null, [], $join_conds ) . ')';
1659         }
1660
1661         public function buildStringCast( $field ) {
1662                 return $field;
1663         }
1664
1665         public function selectDB( $db ) {
1666                 # Stub. Shouldn't cause serious problems if it's not overridden, but
1667                 # if your database engine supports a concept similar to MySQL's
1668                 # databases you may as well.
1669                 $this->mDBname = $db;
1670
1671                 return true;
1672         }
1673
1674         public function getDBname() {
1675                 return $this->mDBname;
1676         }
1677
1678         public function getServer() {
1679                 return $this->mServer;
1680         }
1681
1682         public function tableName( $name, $format = 'quoted' ) {
1683                 # Skip the entire process when we have a string quoted on both ends.
1684                 # Note that we check the end so that we will still quote any use of
1685                 # use of `database`.table. But won't break things if someone wants
1686                 # to query a database table with a dot in the name.
1687                 if ( $this->isQuotedIdentifier( $name ) ) {
1688                         return $name;
1689                 }
1690
1691                 # Lets test for any bits of text that should never show up in a table
1692                 # name. Basically anything like JOIN or ON which are actually part of
1693                 # SQL queries, but may end up inside of the table value to combine
1694                 # sql. Such as how the API is doing.
1695                 # Note that we use a whitespace test rather than a \b test to avoid
1696                 # any remote case where a word like on may be inside of a table name
1697                 # surrounded by symbols which may be considered word breaks.
1698                 if ( preg_match( '/(^|\s)(DISTINCT|JOIN|ON|AS)(\s|$)/i', $name ) !== 0 ) {
1699                         return $name;
1700                 }
1701
1702                 # Split database and table into proper variables.
1703                 # We reverse the explode so that database.table and table both output
1704                 # the correct table.
1705                 $dbDetails = explode( '.', $name, 3 );
1706                 if ( count( $dbDetails ) == 3 ) {
1707                         list( $database, $schema, $table ) = $dbDetails;
1708                         # We don't want any prefix added in this case
1709                         $prefix = '';
1710                 } elseif ( count( $dbDetails ) == 2 ) {
1711                         list( $database, $table ) = $dbDetails;
1712                         # We don't want any prefix added in this case
1713                         # In dbs that support it, $database may actually be the schema
1714                         # but that doesn't affect any of the functionality here
1715                         $prefix = '';
1716                         $schema = '';
1717                 } else {
1718                         list( $table ) = $dbDetails;
1719                         if ( isset( $this->tableAliases[$table] ) ) {
1720                                 $database = $this->tableAliases[$table]['dbname'];
1721                                 $schema = is_string( $this->tableAliases[$table]['schema'] )
1722                                         ? $this->tableAliases[$table]['schema']
1723                                         : $this->mSchema;
1724                                 $prefix = is_string( $this->tableAliases[$table]['prefix'] )
1725                                         ? $this->tableAliases[$table]['prefix']
1726                                         : $this->mTablePrefix;
1727                         } else {
1728                                 $database = '';
1729                                 $schema = $this->mSchema; # Default schema
1730                                 $prefix = $this->mTablePrefix; # Default prefix
1731                         }
1732                 }
1733
1734                 # Quote $table and apply the prefix if not quoted.
1735                 # $tableName might be empty if this is called from Database::replaceVars()
1736                 $tableName = "{$prefix}{$table}";
1737                 if ( $format == 'quoted'
1738                         && !$this->isQuotedIdentifier( $tableName ) && $tableName !== ''
1739                 ) {
1740                         $tableName = $this->addIdentifierQuotes( $tableName );
1741                 }
1742
1743                 # Quote $schema and merge it with the table name if needed
1744                 if ( strlen( $schema ) ) {
1745                         if ( $format == 'quoted' && !$this->isQuotedIdentifier( $schema ) ) {
1746                                 $schema = $this->addIdentifierQuotes( $schema );
1747                         }
1748                         $tableName = $schema . '.' . $tableName;
1749                 }
1750
1751                 # Quote $database and merge it with the table name if needed
1752                 if ( $database !== '' ) {
1753                         if ( $format == 'quoted' && !$this->isQuotedIdentifier( $database ) ) {
1754                                 $database = $this->addIdentifierQuotes( $database );
1755                         }
1756                         $tableName = $database . '.' . $tableName;
1757                 }
1758
1759                 return $tableName;
1760         }
1761
1762         public function tableNames() {
1763                 $inArray = func_get_args();
1764                 $retVal = [];
1765
1766                 foreach ( $inArray as $name ) {
1767                         $retVal[$name] = $this->tableName( $name );
1768                 }
1769
1770                 return $retVal;
1771         }
1772
1773         public function tableNamesN() {
1774                 $inArray = func_get_args();
1775                 $retVal = [];
1776
1777                 foreach ( $inArray as $name ) {
1778                         $retVal[] = $this->tableName( $name );
1779                 }
1780
1781                 return $retVal;
1782         }
1783
1784         /**
1785          * Get an aliased table name
1786          * e.g. tableName AS newTableName
1787          *
1788          * @param string $name Table name, see tableName()
1789          * @param string|bool $alias Alias (optional)
1790          * @return string SQL name for aliased table. Will not alias a table to its own name
1791          */
1792         protected function tableNameWithAlias( $name, $alias = false ) {
1793                 if ( !$alias || $alias == $name ) {
1794                         return $this->tableName( $name );
1795                 } else {
1796                         return $this->tableName( $name ) . ' ' . $this->addIdentifierQuotes( $alias );
1797                 }
1798         }
1799
1800         /**
1801          * Gets an array of aliased table names
1802          *
1803          * @param array $tables [ [alias] => table ]
1804          * @return string[] See tableNameWithAlias()
1805          */
1806         protected function tableNamesWithAlias( $tables ) {
1807                 $retval = [];
1808                 foreach ( $tables as $alias => $table ) {
1809                         if ( is_numeric( $alias ) ) {
1810                                 $alias = $table;
1811                         }
1812                         $retval[] = $this->tableNameWithAlias( $table, $alias );
1813                 }
1814
1815                 return $retval;
1816         }
1817
1818         /**
1819          * Get an aliased field name
1820          * e.g. fieldName AS newFieldName
1821          *
1822          * @param string $name Field name
1823          * @param string|bool $alias Alias (optional)
1824          * @return string SQL name for aliased field. Will not alias a field to its own name
1825          */
1826         protected function fieldNameWithAlias( $name, $alias = false ) {
1827                 if ( !$alias || (string)$alias === (string)$name ) {
1828                         return $name;
1829                 } else {
1830                         return $name . ' AS ' . $this->addIdentifierQuotes( $alias ); // PostgreSQL needs AS
1831                 }
1832         }
1833
1834         /**
1835          * Gets an array of aliased field names
1836          *
1837          * @param array $fields [ [alias] => field ]
1838          * @return string[] See fieldNameWithAlias()
1839          */
1840         protected function fieldNamesWithAlias( $fields ) {
1841                 $retval = [];
1842                 foreach ( $fields as $alias => $field ) {
1843                         if ( is_numeric( $alias ) ) {
1844                                 $alias = $field;
1845                         }
1846                         $retval[] = $this->fieldNameWithAlias( $field, $alias );
1847                 }
1848
1849                 return $retval;
1850         }
1851
1852         /**
1853          * Get the aliased table name clause for a FROM clause
1854          * which might have a JOIN and/or USE INDEX or IGNORE INDEX clause
1855          *
1856          * @param array $tables ( [alias] => table )
1857          * @param array $use_index Same as for select()
1858          * @param array $ignore_index Same as for select()
1859          * @param array $join_conds Same as for select()
1860          * @return string
1861          */
1862         protected function tableNamesWithIndexClauseOrJOIN(
1863                 $tables, $use_index = [], $ignore_index = [], $join_conds = []
1864         ) {
1865                 $ret = [];
1866                 $retJOIN = [];
1867                 $use_index = (array)$use_index;
1868                 $ignore_index = (array)$ignore_index;
1869                 $join_conds = (array)$join_conds;
1870
1871                 foreach ( $tables as $alias => $table ) {
1872                         if ( !is_string( $alias ) ) {
1873                                 // No alias? Set it equal to the table name
1874                                 $alias = $table;
1875                         }
1876                         // Is there a JOIN clause for this table?
1877                         if ( isset( $join_conds[$alias] ) ) {
1878                                 list( $joinType, $conds ) = $join_conds[$alias];
1879                                 $tableClause = $joinType;
1880                                 $tableClause .= ' ' . $this->tableNameWithAlias( $table, $alias );
1881                                 if ( isset( $use_index[$alias] ) ) { // has USE INDEX?
1882                                         $use = $this->useIndexClause( implode( ',', (array)$use_index[$alias] ) );
1883                                         if ( $use != '' ) {
1884                                                 $tableClause .= ' ' . $use;
1885                                         }
1886                                 }
1887                                 if ( isset( $ignore_index[$alias] ) ) { // has IGNORE INDEX?
1888                                         $ignore = $this->ignoreIndexClause(
1889                                                 implode( ',', (array)$ignore_index[$alias] ) );
1890                                         if ( $ignore != '' ) {
1891                                                 $tableClause .= ' ' . $ignore;
1892                                         }
1893                                 }
1894                                 $on = $this->makeList( (array)$conds, self::LIST_AND );
1895                                 if ( $on != '' ) {
1896                                         $tableClause .= ' ON (' . $on . ')';
1897                                 }
1898
1899                                 $retJOIN[] = $tableClause;
1900                         } elseif ( isset( $use_index[$alias] ) ) {
1901                                 // Is there an INDEX clause for this table?
1902                                 $tableClause = $this->tableNameWithAlias( $table, $alias );
1903                                 $tableClause .= ' ' . $this->useIndexClause(
1904                                                 implode( ',', (array)$use_index[$alias] )
1905                                         );
1906
1907                                 $ret[] = $tableClause;
1908                         } elseif ( isset( $ignore_index[$alias] ) ) {
1909                                 // Is there an INDEX clause for this table?
1910                                 $tableClause = $this->tableNameWithAlias( $table, $alias );
1911                                 $tableClause .= ' ' . $this->ignoreIndexClause(
1912                                                 implode( ',', (array)$ignore_index[$alias] )
1913                                         );
1914
1915                                 $ret[] = $tableClause;
1916                         } else {
1917                                 $tableClause = $this->tableNameWithAlias( $table, $alias );
1918
1919                                 $ret[] = $tableClause;
1920                         }
1921                 }
1922
1923                 // We can't separate explicit JOIN clauses with ',', use ' ' for those
1924                 $implicitJoins = !empty( $ret ) ? implode( ',', $ret ) : "";
1925                 $explicitJoins = !empty( $retJOIN ) ? implode( ' ', $retJOIN ) : "";
1926
1927                 // Compile our final table clause
1928                 return implode( ' ', [ $implicitJoins, $explicitJoins ] );
1929         }
1930
1931         /**
1932          * Get the name of an index in a given table.
1933          *
1934          * @param string $index
1935          * @return string
1936          */
1937         protected function indexName( $index ) {
1938                 return $index;
1939         }
1940
1941         public function addQuotes( $s ) {
1942                 if ( $s instanceof Blob ) {
1943                         $s = $s->fetch();
1944                 }
1945                 if ( $s === null ) {
1946                         return 'NULL';
1947                 } elseif ( is_bool( $s ) ) {
1948                         return (int)$s;
1949                 } else {
1950                         # This will also quote numeric values. This should be harmless,
1951                         # and protects against weird problems that occur when they really
1952                         # _are_ strings such as article titles and string->number->string
1953                         # conversion is not 1:1.
1954                         return "'" . $this->strencode( $s ) . "'";
1955                 }
1956         }
1957
1958         /**
1959          * Quotes an identifier using `backticks` or "double quotes" depending on the database type.
1960          * MySQL uses `backticks` while basically everything else uses double quotes.
1961          * Since MySQL is the odd one out here the double quotes are our generic
1962          * and we implement backticks in DatabaseMysql.
1963          *
1964          * @param string $s
1965          * @return string
1966          */
1967         public function addIdentifierQuotes( $s ) {
1968                 return '"' . str_replace( '"', '""', $s ) . '"';
1969         }
1970
1971         /**
1972          * Returns if the given identifier looks quoted or not according to
1973          * the database convention for quoting identifiers .
1974          *
1975          * @note Do not use this to determine if untrusted input is safe.
1976          *   A malicious user can trick this function.
1977          * @param string $name
1978          * @return bool
1979          */
1980         public function isQuotedIdentifier( $name ) {
1981                 return $name[0] == '"' && substr( $name, -1, 1 ) == '"';
1982         }
1983
1984         /**
1985          * @param string $s
1986          * @return string
1987          */
1988         protected function escapeLikeInternal( $s ) {
1989                 return addcslashes( $s, '\%_' );
1990         }
1991
1992         public function buildLike() {
1993                 $params = func_get_args();
1994
1995                 if ( count( $params ) > 0 && is_array( $params[0] ) ) {
1996                         $params = $params[0];
1997                 }
1998
1999                 $s = '';
2000
2001                 foreach ( $params as $value ) {
2002                         if ( $value instanceof LikeMatch ) {
2003                                 $s .= $value->toString();
2004                         } else {
2005                                 $s .= $this->escapeLikeInternal( $value );
2006                         }
2007                 }
2008
2009                 return " LIKE {$this->addQuotes( $s )} ";
2010         }
2011
2012         public function anyChar() {
2013                 return new LikeMatch( '_' );
2014         }
2015
2016         public function anyString() {
2017                 return new LikeMatch( '%' );
2018         }
2019
2020         public function nextSequenceValue( $seqName ) {
2021                 return null;
2022         }
2023
2024         /**
2025          * USE INDEX clause. Unlikely to be useful for anything but MySQL. This
2026          * is only needed because a) MySQL must be as efficient as possible due to
2027          * its use on Wikipedia, and b) MySQL 4.0 is kind of dumb sometimes about
2028          * which index to pick. Anyway, other databases might have different
2029          * indexes on a given table. So don't bother overriding this unless you're
2030          * MySQL.
2031          * @param string $index
2032          * @return string
2033          */
2034         public function useIndexClause( $index ) {
2035                 return '';
2036         }
2037
2038         /**
2039          * IGNORE INDEX clause. Unlikely to be useful for anything but MySQL. This
2040          * is only needed because a) MySQL must be as efficient as possible due to
2041          * its use on Wikipedia, and b) MySQL 4.0 is kind of dumb sometimes about
2042          * which index to pick. Anyway, other databases might have different
2043          * indexes on a given table. So don't bother overriding this unless you're
2044          * MySQL.
2045          * @param string $index
2046          * @return string
2047          */
2048         public function ignoreIndexClause( $index ) {
2049                 return '';
2050         }
2051
2052         public function replace( $table, $uniqueIndexes, $rows, $fname = __METHOD__ ) {
2053                 $quotedTable = $this->tableName( $table );
2054
2055                 if ( count( $rows ) == 0 ) {
2056                         return;
2057                 }
2058
2059                 # Single row case
2060                 if ( !is_array( reset( $rows ) ) ) {
2061                         $rows = [ $rows ];
2062                 }
2063
2064                 // @FXIME: this is not atomic, but a trx would break affectedRows()
2065                 foreach ( $rows as $row ) {
2066                         # Delete rows which collide
2067                         if ( $uniqueIndexes ) {
2068                                 $sql = "DELETE FROM $quotedTable WHERE ";
2069                                 $first = true;
2070                                 foreach ( $uniqueIndexes as $index ) {
2071                                         if ( $first ) {
2072                                                 $first = false;
2073                                                 $sql .= '( ';
2074                                         } else {
2075                                                 $sql .= ' ) OR ( ';
2076                                         }
2077                                         if ( is_array( $index ) ) {
2078                                                 $first2 = true;
2079                                                 foreach ( $index as $col ) {
2080                                                         if ( $first2 ) {
2081                                                                 $first2 = false;
2082                                                         } else {
2083                                                                 $sql .= ' AND ';
2084                                                         }
2085                                                         $sql .= $col . '=' . $this->addQuotes( $row[$col] );
2086                                                 }
2087                                         } else {
2088                                                 $sql .= $index . '=' . $this->addQuotes( $row[$index] );
2089                                         }
2090                                 }
2091                                 $sql .= ' )';
2092                                 $this->query( $sql, $fname );
2093                         }
2094
2095                         # Now insert the row
2096                         $this->insert( $table, $row, $fname );
2097                 }
2098         }
2099
2100         /**
2101          * REPLACE query wrapper for MySQL and SQLite, which have a native REPLACE
2102          * statement.
2103          *
2104          * @param string $table Table name
2105          * @param array|string $rows Row(s) to insert
2106          * @param string $fname Caller function name
2107          *
2108          * @return ResultWrapper
2109          */
2110         protected function nativeReplace( $table, $rows, $fname ) {
2111                 $table = $this->tableName( $table );
2112
2113                 # Single row case
2114                 if ( !is_array( reset( $rows ) ) ) {
2115                         $rows = [ $rows ];
2116                 }
2117
2118                 $sql = "REPLACE INTO $table (" . implode( ',', array_keys( $rows[0] ) ) . ') VALUES ';
2119                 $first = true;
2120
2121                 foreach ( $rows as $row ) {
2122                         if ( $first ) {
2123                                 $first = false;
2124                         } else {
2125                                 $sql .= ',';
2126                         }
2127
2128                         $sql .= '(' . $this->makeList( $row ) . ')';
2129                 }
2130
2131                 return $this->query( $sql, $fname );
2132         }
2133
2134         public function upsert( $table, array $rows, array $uniqueIndexes, array $set,
2135                 $fname = __METHOD__
2136         ) {
2137                 if ( !count( $rows ) ) {
2138                         return true; // nothing to do
2139                 }
2140
2141                 if ( !is_array( reset( $rows ) ) ) {
2142                         $rows = [ $rows ];
2143                 }
2144
2145                 if ( count( $uniqueIndexes ) ) {
2146                         $clauses = []; // list WHERE clauses that each identify a single row
2147                         foreach ( $rows as $row ) {
2148                                 foreach ( $uniqueIndexes as $index ) {
2149                                         $index = is_array( $index ) ? $index : [ $index ]; // columns
2150                                         $rowKey = []; // unique key to this row
2151                                         foreach ( $index as $column ) {
2152                                                 $rowKey[$column] = $row[$column];
2153                                         }
2154                                         $clauses[] = $this->makeList( $rowKey, self::LIST_AND );
2155                                 }
2156                         }
2157                         $where = [ $this->makeList( $clauses, self::LIST_OR ) ];
2158                 } else {
2159                         $where = false;
2160                 }
2161
2162                 $useTrx = !$this->mTrxLevel;
2163                 if ( $useTrx ) {
2164                         $this->begin( $fname, self::TRANSACTION_INTERNAL );
2165                 }
2166                 try {
2167                         # Update any existing conflicting row(s)
2168                         if ( $where !== false ) {
2169                                 $ok = $this->update( $table, $set, $where, $fname );
2170                         } else {
2171                                 $ok = true;
2172                         }
2173                         # Now insert any non-conflicting row(s)
2174                         $ok = $this->insert( $table, $rows, $fname, [ 'IGNORE' ] ) && $ok;
2175                 } catch ( Exception $e ) {
2176                         if ( $useTrx ) {
2177                                 $this->rollback( $fname, self::FLUSHING_INTERNAL );
2178                         }
2179                         throw $e;
2180                 }
2181                 if ( $useTrx ) {
2182                         $this->commit( $fname, self::FLUSHING_INTERNAL );
2183                 }
2184
2185                 return $ok;
2186         }
2187
2188         public function deleteJoin( $delTable, $joinTable, $delVar, $joinVar, $conds,
2189                 $fname = __METHOD__
2190         ) {
2191                 if ( !$conds ) {
2192                         throw new DBUnexpectedError( $this, __METHOD__ . ' called with empty $conds' );
2193                 }
2194
2195                 $delTable = $this->tableName( $delTable );
2196                 $joinTable = $this->tableName( $joinTable );
2197                 $sql = "DELETE FROM $delTable WHERE $delVar IN (SELECT $joinVar FROM $joinTable ";
2198                 if ( $conds != '*' ) {
2199                         $sql .= 'WHERE ' . $this->makeList( $conds, self::LIST_AND );
2200                 }
2201                 $sql .= ')';
2202
2203                 $this->query( $sql, $fname );
2204         }
2205
2206         public function textFieldSize( $table, $field ) {
2207                 $table = $this->tableName( $table );
2208                 $sql = "SHOW COLUMNS FROM $table LIKE \"$field\";";
2209                 $res = $this->query( $sql, __METHOD__ );
2210                 $row = $this->fetchObject( $res );
2211
2212                 $m = [];
2213
2214                 if ( preg_match( '/\((.*)\)/', $row->Type, $m ) ) {
2215                         $size = $m[1];
2216                 } else {
2217                         $size = -1;
2218                 }
2219
2220                 return $size;
2221         }
2222
2223         public function delete( $table, $conds, $fname = __METHOD__ ) {
2224                 if ( !$conds ) {
2225                         throw new DBUnexpectedError( $this, __METHOD__ . ' called with no conditions' );
2226                 }
2227
2228                 $table = $this->tableName( $table );
2229                 $sql = "DELETE FROM $table";
2230
2231                 if ( $conds != '*' ) {
2232                         if ( is_array( $conds ) ) {
2233                                 $conds = $this->makeList( $conds, self::LIST_AND );
2234                         }
2235                         $sql .= ' WHERE ' . $conds;
2236                 }
2237
2238                 return $this->query( $sql, $fname );
2239         }
2240
2241         public function insertSelect(
2242                 $destTable, $srcTable, $varMap, $conds,
2243                 $fname = __METHOD__, $insertOptions = [], $selectOptions = []
2244         ) {
2245                 if ( $this->cliMode ) {
2246                         // For massive migrations with downtime, we don't want to select everything
2247                         // into memory and OOM, so do all this native on the server side if possible.
2248                         return $this->nativeInsertSelect(
2249                                 $destTable,
2250                                 $srcTable,
2251                                 $varMap,
2252                                 $conds,
2253                                 $fname,
2254                                 $insertOptions,
2255                                 $selectOptions
2256                         );
2257                 }
2258
2259                 // For web requests, do a locking SELECT and then INSERT. This puts the SELECT burden
2260                 // on only the master (without needing row-based-replication). It also makes it easy to
2261                 // know how big the INSERT is going to be.
2262                 $fields = [];
2263                 foreach ( $varMap as $dstColumn => $sourceColumnOrSql ) {
2264                         $fields[] = $this->fieldNameWithAlias( $sourceColumnOrSql, $dstColumn );
2265                 }
2266                 $selectOptions[] = 'FOR UPDATE';
2267                 $res = $this->select( $srcTable, implode( ',', $fields ), $conds, $fname, $selectOptions );
2268                 if ( !$res ) {
2269                         return false;
2270                 }
2271
2272                 $rows = [];
2273                 foreach ( $res as $row ) {
2274                         $rows[] = (array)$row;
2275                 }
2276
2277                 return $this->insert( $destTable, $rows, $fname, $insertOptions );
2278         }
2279
2280         protected function nativeInsertSelect( $destTable, $srcTable, $varMap, $conds,
2281                 $fname = __METHOD__,
2282                 $insertOptions = [], $selectOptions = []
2283         ) {
2284                 $destTable = $this->tableName( $destTable );
2285
2286                 if ( !is_array( $insertOptions ) ) {
2287                         $insertOptions = [ $insertOptions ];
2288                 }
2289
2290                 $insertOptions = $this->makeInsertOptions( $insertOptions );
2291
2292                 if ( !is_array( $selectOptions ) ) {
2293                         $selectOptions = [ $selectOptions ];
2294                 }
2295
2296                 list( $startOpts, $useIndex, $tailOpts, $ignoreIndex ) = $this->makeSelectOptions(
2297                         $selectOptions );
2298
2299                 if ( is_array( $srcTable ) ) {
2300                         $srcTable = implode( ',', array_map( [ &$this, 'tableName' ], $srcTable ) );
2301                 } else {
2302                         $srcTable = $this->tableName( $srcTable );
2303                 }
2304
2305                 $sql = "INSERT $insertOptions" .
2306                         " INTO $destTable (" . implode( ',', array_keys( $varMap ) ) . ')' .
2307                         " SELECT $startOpts " . implode( ',', $varMap ) .
2308                         " FROM $srcTable $useIndex $ignoreIndex ";
2309
2310                 if ( $conds != '*' ) {
2311                         if ( is_array( $conds ) ) {
2312                                 $conds = $this->makeList( $conds, self::LIST_AND );
2313                         }
2314                         $sql .= " WHERE $conds";
2315                 }
2316
2317                 $sql .= " $tailOpts";
2318
2319                 return $this->query( $sql, $fname );
2320         }
2321
2322         /**
2323          * Construct a LIMIT query with optional offset. This is used for query
2324          * pages. The SQL should be adjusted so that only the first $limit rows
2325          * are returned. If $offset is provided as well, then the first $offset
2326          * rows should be discarded, and the next $limit rows should be returned.
2327          * If the result of the query is not ordered, then the rows to be returned
2328          * are theoretically arbitrary.
2329          *
2330          * $sql is expected to be a SELECT, if that makes a difference.
2331          *
2332          * The version provided by default works in MySQL and SQLite. It will very
2333          * likely need to be overridden for most other DBMSes.
2334          *
2335          * @param string $sql SQL query we will append the limit too
2336          * @param int $limit The SQL limit
2337          * @param int|bool $offset The SQL offset (default false)
2338          * @throws DBUnexpectedError
2339          * @return string
2340          */
2341         public function limitResult( $sql, $limit, $offset = false ) {
2342                 if ( !is_numeric( $limit ) ) {
2343                         throw new DBUnexpectedError( $this,
2344                                 "Invalid non-numeric limit passed to limitResult()\n" );
2345                 }
2346
2347                 return "$sql LIMIT "
2348                 . ( ( is_numeric( $offset ) && $offset != 0 ) ? "{$offset}," : "" )
2349                 . "{$limit} ";
2350         }
2351
2352         public function unionSupportsOrderAndLimit() {
2353                 return true; // True for almost every DB supported
2354         }
2355
2356         public function unionQueries( $sqls, $all ) {
2357                 $glue = $all ? ') UNION ALL (' : ') UNION (';
2358
2359                 return '(' . implode( $glue, $sqls ) . ')';
2360         }
2361
2362         public function conditional( $cond, $trueVal, $falseVal ) {
2363                 if ( is_array( $cond ) ) {
2364                         $cond = $this->makeList( $cond, self::LIST_AND );
2365                 }
2366
2367                 return " (CASE WHEN $cond THEN $trueVal ELSE $falseVal END) ";
2368         }
2369
2370         public function strreplace( $orig, $old, $new ) {
2371                 return "REPLACE({$orig}, {$old}, {$new})";
2372         }
2373
2374         public function getServerUptime() {
2375                 return 0;
2376         }
2377
2378         public function wasDeadlock() {
2379                 return false;
2380         }
2381
2382         public function wasLockTimeout() {
2383                 return false;
2384         }
2385
2386         public function wasErrorReissuable() {
2387                 return false;
2388         }
2389
2390         public function wasReadOnlyError() {
2391                 return false;
2392         }
2393
2394         /**
2395          * Do not use this method outside of Database/DBError classes
2396          *
2397          * @param integer|string $errno
2398          * @return bool Whether the given query error was a connection drop
2399          */
2400         public function wasConnectionError( $errno ) {
2401                 return false;
2402         }
2403
2404         public function deadlockLoop() {
2405                 $args = func_get_args();
2406                 $function = array_shift( $args );
2407                 $tries = self::DEADLOCK_TRIES;
2408
2409                 $this->begin( __METHOD__ );
2410
2411                 $retVal = null;
2412                 /** @var Exception $e */
2413                 $e = null;
2414                 do {
2415                         try {
2416                                 $retVal = call_user_func_array( $function, $args );
2417                                 break;
2418                         } catch ( DBQueryError $e ) {
2419                                 if ( $this->wasDeadlock() ) {
2420                                         // Retry after a randomized delay
2421                                         usleep( mt_rand( self::DEADLOCK_DELAY_MIN, self::DEADLOCK_DELAY_MAX ) );
2422                                 } else {
2423                                         // Throw the error back up
2424                                         throw $e;
2425                                 }
2426                         }
2427                 } while ( --$tries > 0 );
2428
2429                 if ( $tries <= 0 ) {
2430                         // Too many deadlocks; give up
2431                         $this->rollback( __METHOD__ );
2432                         throw $e;
2433                 } else {
2434                         $this->commit( __METHOD__ );
2435
2436                         return $retVal;
2437                 }
2438         }
2439
2440         public function masterPosWait( DBMasterPos $pos, $timeout ) {
2441                 # Real waits are implemented in the subclass.
2442                 return 0;
2443         }
2444
2445         public function getReplicaPos() {
2446                 # Stub
2447                 return false;
2448         }
2449
2450         public function getMasterPos() {
2451                 # Stub
2452                 return false;
2453         }
2454
2455         public function serverIsReadOnly() {
2456                 return false;
2457         }
2458
2459         final public function onTransactionResolution( callable $callback, $fname = __METHOD__ ) {
2460                 if ( !$this->mTrxLevel ) {
2461                         throw new DBUnexpectedError( $this, "No transaction is active." );
2462                 }
2463                 $this->mTrxEndCallbacks[] = [ $callback, $fname ];
2464         }
2465
2466         final public function onTransactionIdle( callable $callback, $fname = __METHOD__ ) {
2467                 $this->mTrxIdleCallbacks[] = [ $callback, $fname ];
2468                 if ( !$this->mTrxLevel ) {
2469                         $this->runOnTransactionIdleCallbacks( self::TRIGGER_IDLE );
2470                 }
2471         }
2472
2473         final public function onTransactionPreCommitOrIdle( callable $callback, $fname = __METHOD__ ) {
2474                 if ( $this->mTrxLevel ) {
2475                         $this->mTrxPreCommitCallbacks[] = [ $callback, $fname ];
2476                 } else {
2477                         // If no transaction is active, then make one for this callback
2478                         $this->startAtomic( __METHOD__ );
2479                         try {
2480                                 call_user_func( $callback );
2481                                 $this->endAtomic( __METHOD__ );
2482                         } catch ( Exception $e ) {
2483                                 $this->rollback( __METHOD__, self::FLUSHING_INTERNAL );
2484                                 throw $e;
2485                         }
2486                 }
2487         }
2488
2489         final public function setTransactionListener( $name, callable $callback = null ) {
2490                 if ( $callback ) {
2491                         $this->mTrxRecurringCallbacks[$name] = $callback;
2492                 } else {
2493                         unset( $this->mTrxRecurringCallbacks[$name] );
2494                 }
2495         }
2496
2497         /**
2498          * Whether to disable running of post-COMMIT/ROLLBACK callbacks
2499          *
2500          * This method should not be used outside of Database/LoadBalancer
2501          *
2502          * @param bool $suppress
2503          * @since 1.28
2504          */
2505         final public function setTrxEndCallbackSuppression( $suppress ) {
2506                 $this->mTrxEndCallbacksSuppressed = $suppress;
2507         }
2508
2509         /**
2510          * Actually run and consume any "on transaction idle/resolution" callbacks.
2511          *
2512          * This method should not be used outside of Database/LoadBalancer
2513          *
2514          * @param integer $trigger IDatabase::TRIGGER_* constant
2515          * @since 1.20
2516          * @throws Exception
2517          */
2518         public function runOnTransactionIdleCallbacks( $trigger ) {
2519                 if ( $this->mTrxEndCallbacksSuppressed ) {
2520                         return;
2521                 }
2522
2523                 $autoTrx = $this->getFlag( self::DBO_TRX ); // automatic begin() enabled?
2524                 /** @var Exception $e */
2525                 $e = null; // first exception
2526                 do { // callbacks may add callbacks :)
2527                         $callbacks = array_merge(
2528                                 $this->mTrxIdleCallbacks,
2529                                 $this->mTrxEndCallbacks // include "transaction resolution" callbacks
2530                         );
2531                         $this->mTrxIdleCallbacks = []; // consumed (and recursion guard)
2532                         $this->mTrxEndCallbacks = []; // consumed (recursion guard)
2533                         foreach ( $callbacks as $callback ) {
2534                                 try {
2535                                         list( $phpCallback ) = $callback;
2536                                         $this->clearFlag( self::DBO_TRX ); // make each query its own transaction
2537                                         call_user_func_array( $phpCallback, [ $trigger ] );
2538                                         if ( $autoTrx ) {
2539                                                 $this->setFlag( self::DBO_TRX ); // restore automatic begin()
2540                                         } else {
2541                                                 $this->clearFlag( self::DBO_TRX ); // restore auto-commit
2542                                         }
2543                                 } catch ( Exception $ex ) {
2544                                         call_user_func( $this->errorLogger, $ex );
2545                                         $e = $e ?: $ex;
2546                                         // Some callbacks may use startAtomic/endAtomic, so make sure
2547                                         // their transactions are ended so other callbacks don't fail
2548                                         if ( $this->trxLevel() ) {
2549                                                 $this->rollback( __METHOD__, self::FLUSHING_INTERNAL );
2550                                         }
2551                                 }
2552                         }
2553                 } while ( count( $this->mTrxIdleCallbacks ) );
2554
2555                 if ( $e instanceof Exception ) {
2556                         throw $e; // re-throw any first exception
2557                 }
2558         }
2559
2560         /**
2561          * Actually run and consume any "on transaction pre-commit" callbacks.
2562          *
2563          * This method should not be used outside of Database/LoadBalancer
2564          *
2565          * @since 1.22
2566          * @throws Exception
2567          */
2568         public function runOnTransactionPreCommitCallbacks() {
2569                 $e = null; // first exception
2570                 do { // callbacks may add callbacks :)
2571                         $callbacks = $this->mTrxPreCommitCallbacks;
2572                         $this->mTrxPreCommitCallbacks = []; // consumed (and recursion guard)
2573                         foreach ( $callbacks as $callback ) {
2574                                 try {
2575                                         list( $phpCallback ) = $callback;
2576                                         call_user_func( $phpCallback );
2577                                 } catch ( Exception $ex ) {
2578                                         call_user_func( $this->errorLogger, $ex );
2579                                         $e = $e ?: $ex;
2580                                 }
2581                         }
2582                 } while ( count( $this->mTrxPreCommitCallbacks ) );
2583
2584                 if ( $e instanceof Exception ) {
2585                         throw $e; // re-throw any first exception
2586                 }
2587         }
2588
2589         /**
2590          * Actually run any "transaction listener" callbacks.
2591          *
2592          * This method should not be used outside of Database/LoadBalancer
2593          *
2594          * @param integer $trigger IDatabase::TRIGGER_* constant
2595          * @throws Exception
2596          * @since 1.20
2597          */
2598         public function runTransactionListenerCallbacks( $trigger ) {
2599                 if ( $this->mTrxEndCallbacksSuppressed ) {
2600                         return;
2601                 }
2602
2603                 /** @var Exception $e */
2604                 $e = null; // first exception
2605
2606                 foreach ( $this->mTrxRecurringCallbacks as $phpCallback ) {
2607                         try {
2608                                 $phpCallback( $trigger, $this );
2609                         } catch ( Exception $ex ) {
2610                                 call_user_func( $this->errorLogger, $ex );
2611                                 $e = $e ?: $ex;
2612                         }
2613                 }
2614
2615                 if ( $e instanceof Exception ) {
2616                         throw $e; // re-throw any first exception
2617                 }
2618         }
2619
2620         final public function startAtomic( $fname = __METHOD__ ) {
2621                 if ( !$this->mTrxLevel ) {
2622                         $this->begin( $fname, self::TRANSACTION_INTERNAL );
2623                         // If DBO_TRX is set, a series of startAtomic/endAtomic pairs will result
2624                         // in all changes being in one transaction to keep requests transactional.
2625                         if ( !$this->getFlag( self::DBO_TRX ) ) {
2626                                 $this->mTrxAutomaticAtomic = true;
2627                         }
2628                 }
2629
2630                 $this->mTrxAtomicLevels[] = $fname;
2631         }
2632
2633         final public function endAtomic( $fname = __METHOD__ ) {
2634                 if ( !$this->mTrxLevel ) {
2635                         throw new DBUnexpectedError( $this, "No atomic transaction is open (got $fname)." );
2636                 }
2637                 if ( !$this->mTrxAtomicLevels ||
2638                         array_pop( $this->mTrxAtomicLevels ) !== $fname
2639                 ) {
2640                         throw new DBUnexpectedError( $this, "Invalid atomic section ended (got $fname)." );
2641                 }
2642
2643                 if ( !$this->mTrxAtomicLevels && $this->mTrxAutomaticAtomic ) {
2644                         $this->commit( $fname, self::FLUSHING_INTERNAL );
2645                 }
2646         }
2647
2648         final public function doAtomicSection( $fname, callable $callback ) {
2649                 $this->startAtomic( $fname );
2650                 try {
2651                         $res = call_user_func_array( $callback, [ $this, $fname ] );
2652                 } catch ( Exception $e ) {
2653                         $this->rollback( $fname, self::FLUSHING_INTERNAL );
2654                         throw $e;
2655                 }
2656                 $this->endAtomic( $fname );
2657
2658                 return $res;
2659         }
2660
2661         final public function begin( $fname = __METHOD__, $mode = self::TRANSACTION_EXPLICIT ) {
2662                 // Protect against mismatched atomic section, transaction nesting, and snapshot loss
2663                 if ( $this->mTrxLevel ) {
2664                         if ( $this->mTrxAtomicLevels ) {
2665                                 $levels = implode( ', ', $this->mTrxAtomicLevels );
2666                                 $msg = "$fname: Got explicit BEGIN while atomic section(s) $levels are open.";
2667                                 throw new DBUnexpectedError( $this, $msg );
2668                         } elseif ( !$this->mTrxAutomatic ) {
2669                                 $msg = "$fname: Explicit transaction already active (from {$this->mTrxFname}).";
2670                                 throw new DBUnexpectedError( $this, $msg );
2671                         } else {
2672                                 // @TODO: make this an exception at some point
2673                                 $msg = "$fname: Implicit transaction already active (from {$this->mTrxFname}).";
2674                                 $this->queryLogger->error( $msg );
2675                                 return; // join the main transaction set
2676                         }
2677                 } elseif ( $this->getFlag( self::DBO_TRX ) && $mode !== self::TRANSACTION_INTERNAL ) {
2678                         // @TODO: make this an exception at some point
2679                         $msg = "$fname: Implicit transaction expected (DBO_TRX set).";
2680                         $this->queryLogger->error( $msg );
2681                         return; // let any writes be in the main transaction
2682                 }
2683
2684                 // Avoid fatals if close() was called
2685                 $this->assertOpen();
2686
2687                 $this->doBegin( $fname );
2688                 $this->mTrxTimestamp = microtime( true );
2689                 $this->mTrxFname = $fname;
2690                 $this->mTrxDoneWrites = false;
2691                 $this->mTrxAutomaticAtomic = false;
2692                 $this->mTrxAtomicLevels = [];
2693                 $this->mTrxShortId = sprintf( '%06x', mt_rand( 0, 0xffffff ) );
2694                 $this->mTrxWriteDuration = 0.0;
2695                 $this->mTrxWriteQueryCount = 0;
2696                 $this->mTrxWriteAdjDuration = 0.0;
2697                 $this->mTrxWriteAdjQueryCount = 0;
2698                 $this->mTrxWriteCallers = [];
2699                 // First SELECT after BEGIN will establish the snapshot in REPEATABLE-READ.
2700                 // Get an estimate of the replica DB lag before then, treating estimate staleness
2701                 // as lag itself just to be safe
2702                 $status = $this->getApproximateLagStatus();
2703                 $this->mTrxReplicaLag = $status['lag'] + ( microtime( true ) - $status['since'] );
2704                 // T147697: make explicitTrxActive() return true until begin() finishes. This way, no
2705                 // caller will think its OK to muck around with the transaction just because startAtomic()
2706                 // has not yet completed (e.g. setting mTrxAtomicLevels).
2707                 $this->mTrxAutomatic = ( $mode === self::TRANSACTION_INTERNAL );
2708         }
2709
2710         /**
2711          * Issues the BEGIN command to the database server.
2712          *
2713          * @see Database::begin()
2714          * @param string $fname
2715          */
2716         protected function doBegin( $fname ) {
2717                 $this->query( 'BEGIN', $fname );
2718                 $this->mTrxLevel = 1;
2719         }
2720
2721         final public function commit( $fname = __METHOD__, $flush = '' ) {
2722                 if ( $this->mTrxLevel && $this->mTrxAtomicLevels ) {
2723                         // There are still atomic sections open. This cannot be ignored
2724                         $levels = implode( ', ', $this->mTrxAtomicLevels );
2725                         throw new DBUnexpectedError(
2726                                 $this,
2727                                 "$fname: Got COMMIT while atomic sections $levels are still open."
2728                         );
2729                 }
2730
2731                 if ( $flush === self::FLUSHING_INTERNAL || $flush === self::FLUSHING_ALL_PEERS ) {
2732                         if ( !$this->mTrxLevel ) {
2733                                 return; // nothing to do
2734                         } elseif ( !$this->mTrxAutomatic ) {
2735                                 throw new DBUnexpectedError(
2736                                         $this,
2737                                         "$fname: Flushing an explicit transaction, getting out of sync."
2738                                 );
2739                         }
2740                 } else {
2741                         if ( !$this->mTrxLevel ) {
2742                                 $this->queryLogger->error(
2743                                         "$fname: No transaction to commit, something got out of sync." );
2744                                 return; // nothing to do
2745                         } elseif ( $this->mTrxAutomatic ) {
2746                                 // @TODO: make this an exception at some point
2747                                 $msg = "$fname: Explicit commit of implicit transaction.";
2748                                 $this->queryLogger->error( $msg );
2749                                 return; // wait for the main transaction set commit round
2750                         }
2751                 }
2752
2753                 // Avoid fatals if close() was called
2754                 $this->assertOpen();
2755
2756                 $this->runOnTransactionPreCommitCallbacks();
2757                 $writeTime = $this->pendingWriteQueryDuration( self::ESTIMATE_DB_APPLY );
2758                 $this->doCommit( $fname );
2759                 if ( $this->mTrxDoneWrites ) {
2760                         $this->mLastWriteTime = microtime( true );
2761                         $this->trxProfiler->transactionWritingOut(
2762                                 $this->mServer, $this->mDBname, $this->mTrxShortId, $writeTime );
2763                 }
2764
2765                 $this->runOnTransactionIdleCallbacks( self::TRIGGER_COMMIT );
2766                 $this->runTransactionListenerCallbacks( self::TRIGGER_COMMIT );
2767         }
2768
2769         /**
2770          * Issues the COMMIT command to the database server.
2771          *
2772          * @see Database::commit()
2773          * @param string $fname
2774          */
2775         protected function doCommit( $fname ) {
2776                 if ( $this->mTrxLevel ) {
2777                         $this->query( 'COMMIT', $fname );
2778                         $this->mTrxLevel = 0;
2779                 }
2780         }
2781
2782         final public function rollback( $fname = __METHOD__, $flush = '' ) {
2783                 if ( $flush === self::FLUSHING_INTERNAL || $flush === self::FLUSHING_ALL_PEERS ) {
2784                         if ( !$this->mTrxLevel ) {
2785                                 return; // nothing to do
2786                         }
2787                 } else {
2788                         if ( !$this->mTrxLevel ) {
2789                                 $this->queryLogger->error(
2790                                         "$fname: No transaction to rollback, something got out of sync." );
2791                                 return; // nothing to do
2792                         } elseif ( $this->getFlag( self::DBO_TRX ) ) {
2793                                 throw new DBUnexpectedError(
2794                                         $this,
2795                                         "$fname: Expected mass rollback of all peer databases (DBO_TRX set)."
2796                                 );
2797                         }
2798                 }
2799
2800                 // Avoid fatals if close() was called
2801                 $this->assertOpen();
2802
2803                 $this->doRollback( $fname );
2804                 $this->mTrxAtomicLevels = [];
2805                 if ( $this->mTrxDoneWrites ) {
2806                         $this->trxProfiler->transactionWritingOut(
2807                                 $this->mServer, $this->mDBname, $this->mTrxShortId );
2808                 }
2809
2810                 $this->mTrxIdleCallbacks = []; // clear
2811                 $this->mTrxPreCommitCallbacks = []; // clear
2812                 $this->runOnTransactionIdleCallbacks( self::TRIGGER_ROLLBACK );
2813                 $this->runTransactionListenerCallbacks( self::TRIGGER_ROLLBACK );
2814         }
2815
2816         /**
2817          * Issues the ROLLBACK command to the database server.
2818          *
2819          * @see Database::rollback()
2820          * @param string $fname
2821          */
2822         protected function doRollback( $fname ) {
2823                 if ( $this->mTrxLevel ) {
2824                         # Disconnects cause rollback anyway, so ignore those errors
2825                         $ignoreErrors = true;
2826                         $this->query( 'ROLLBACK', $fname, $ignoreErrors );
2827                         $this->mTrxLevel = 0;
2828                 }
2829         }
2830
2831         public function flushSnapshot( $fname = __METHOD__ ) {
2832                 if ( $this->writesOrCallbacksPending() || $this->explicitTrxActive() ) {
2833                         // This only flushes transactions to clear snapshots, not to write data
2834                         $fnames = implode( ', ', $this->pendingWriteAndCallbackCallers() );
2835                         throw new DBUnexpectedError(
2836                                 $this,
2837                                 "$fname: Cannot COMMIT to clear snapshot because writes are pending ($fnames)."
2838                         );
2839                 }
2840
2841                 $this->commit( $fname, self::FLUSHING_INTERNAL );
2842         }
2843
2844         public function explicitTrxActive() {
2845                 return $this->mTrxLevel && ( $this->mTrxAtomicLevels || !$this->mTrxAutomatic );
2846         }
2847
2848         /**
2849          * Creates a new table with structure copied from existing table
2850          * Note that unlike most database abstraction functions, this function does not
2851          * automatically append database prefix, because it works at a lower
2852          * abstraction level.
2853          * The table names passed to this function shall not be quoted (this
2854          * function calls addIdentifierQuotes when needed).
2855          *
2856          * @param string $oldName Name of table whose structure should be copied
2857          * @param string $newName Name of table to be created
2858          * @param bool $temporary Whether the new table should be temporary
2859          * @param string $fname Calling function name
2860          * @throws RuntimeException
2861          * @return bool True if operation was successful
2862          */
2863         public function duplicateTableStructure( $oldName, $newName, $temporary = false,
2864                 $fname = __METHOD__
2865         ) {
2866                 throw new RuntimeException( __METHOD__ . ' is not implemented in descendant class' );
2867         }
2868
2869         public function listTables( $prefix = null, $fname = __METHOD__ ) {
2870                 throw new RuntimeException( __METHOD__ . ' is not implemented in descendant class' );
2871         }
2872
2873         public function listViews( $prefix = null, $fname = __METHOD__ ) {
2874                 throw new RuntimeException( __METHOD__ . ' is not implemented in descendant class' );
2875         }
2876
2877         public function timestamp( $ts = 0 ) {
2878                 $t = new ConvertibleTimestamp( $ts );
2879                 // Let errors bubble up to avoid putting garbage in the DB
2880                 return $t->getTimestamp( TS_MW );
2881         }
2882
2883         public function timestampOrNull( $ts = null ) {
2884                 if ( is_null( $ts ) ) {
2885                         return null;
2886                 } else {
2887                         return $this->timestamp( $ts );
2888                 }
2889         }
2890
2891         /**
2892          * Take the result from a query, and wrap it in a ResultWrapper if
2893          * necessary. Boolean values are passed through as is, to indicate success
2894          * of write queries or failure.
2895          *
2896          * Once upon a time, Database::query() returned a bare MySQL result
2897          * resource, and it was necessary to call this function to convert it to
2898          * a wrapper. Nowadays, raw database objects are never exposed to external
2899          * callers, so this is unnecessary in external code.
2900          *
2901          * @param bool|ResultWrapper|resource|object $result
2902          * @return bool|ResultWrapper
2903          */
2904         protected function resultObject( $result ) {
2905                 if ( !$result ) {
2906                         return false;
2907                 } elseif ( $result instanceof ResultWrapper ) {
2908                         return $result;
2909                 } elseif ( $result === true ) {
2910                         // Successful write query
2911                         return $result;
2912                 } else {
2913                         return new ResultWrapper( $this, $result );
2914                 }
2915         }
2916
2917         public function ping( &$rtt = null ) {
2918                 // Avoid hitting the server if it was hit recently
2919                 if ( $this->isOpen() && ( microtime( true ) - $this->lastPing ) < self::PING_TTL ) {
2920                         if ( !func_num_args() || $this->mRTTEstimate > 0 ) {
2921                                 $rtt = $this->mRTTEstimate;
2922                                 return true; // don't care about $rtt
2923                         }
2924                 }
2925
2926                 // This will reconnect if possible or return false if not
2927                 $this->clearFlag( self::DBO_TRX, self::REMEMBER_PRIOR );
2928                 $ok = ( $this->query( self::PING_QUERY, __METHOD__, true ) !== false );
2929                 $this->restoreFlags( self::RESTORE_PRIOR );
2930
2931                 if ( $ok ) {
2932                         $rtt = $this->mRTTEstimate;
2933                 }
2934
2935                 return $ok;
2936         }
2937
2938         /**
2939          * @return bool
2940          */
2941         protected function reconnect() {
2942                 $this->closeConnection();
2943                 $this->mOpened = false;
2944                 $this->mConn = false;
2945                 try {
2946                         $this->open( $this->mServer, $this->mUser, $this->mPassword, $this->mDBname );
2947                         $this->lastPing = microtime( true );
2948                         $ok = true;
2949                 } catch ( DBConnectionError $e ) {
2950                         $ok = false;
2951                 }
2952
2953                 return $ok;
2954         }
2955
2956         public function getSessionLagStatus() {
2957                 return $this->getTransactionLagStatus() ?: $this->getApproximateLagStatus();
2958         }
2959
2960         /**
2961          * Get the replica DB lag when the current transaction started
2962          *
2963          * This is useful when transactions might use snapshot isolation
2964          * (e.g. REPEATABLE-READ in innodb), so the "real" lag of that data
2965          * is this lag plus transaction duration. If they don't, it is still
2966          * safe to be pessimistic. This returns null if there is no transaction.
2967          *
2968          * @return array|null ('lag': seconds or false on error, 'since': UNIX timestamp of BEGIN)
2969          * @since 1.27
2970          */
2971         protected function getTransactionLagStatus() {
2972                 return $this->mTrxLevel
2973                         ? [ 'lag' => $this->mTrxReplicaLag, 'since' => $this->trxTimestamp() ]
2974                         : null;
2975         }
2976
2977         /**
2978          * Get a replica DB lag estimate for this server
2979          *
2980          * @return array ('lag': seconds or false on error, 'since': UNIX timestamp of estimate)
2981          * @since 1.27
2982          */
2983         protected function getApproximateLagStatus() {
2984                 return [
2985                         'lag'   => $this->getLBInfo( 'replica' ) ? $this->getLag() : 0,
2986                         'since' => microtime( true )
2987                 ];
2988         }
2989
2990         /**
2991          * Merge the result of getSessionLagStatus() for several DBs
2992          * using the most pessimistic values to estimate the lag of
2993          * any data derived from them in combination
2994          *
2995          * This is information is useful for caching modules
2996          *
2997          * @see WANObjectCache::set()
2998          * @see WANObjectCache::getWithSetCallback()
2999          *
3000          * @param IDatabase $db1
3001          * @param IDatabase ...
3002          * @return array Map of values:
3003          *   - lag: highest lag of any of the DBs or false on error (e.g. replication stopped)
3004          *   - since: oldest UNIX timestamp of any of the DB lag estimates
3005          *   - pending: whether any of the DBs have uncommitted changes
3006          * @since 1.27
3007          */
3008         public static function getCacheSetOptions( IDatabase $db1 ) {
3009                 $res = [ 'lag' => 0, 'since' => INF, 'pending' => false ];
3010                 foreach ( func_get_args() as $db ) {
3011                         /** @var IDatabase $db */
3012                         $status = $db->getSessionLagStatus();
3013                         if ( $status['lag'] === false ) {
3014                                 $res['lag'] = false;
3015                         } elseif ( $res['lag'] !== false ) {
3016                                 $res['lag'] = max( $res['lag'], $status['lag'] );
3017                         }
3018                         $res['since'] = min( $res['since'], $status['since'] );
3019                         $res['pending'] = $res['pending'] ?: $db->writesPending();
3020                 }
3021
3022                 return $res;
3023         }
3024
3025         public function getLag() {
3026                 return 0;
3027         }
3028
3029         public function maxListLen() {
3030                 return 0;
3031         }
3032
3033         public function encodeBlob( $b ) {
3034                 return $b;
3035         }
3036
3037         public function decodeBlob( $b ) {
3038                 if ( $b instanceof Blob ) {
3039                         $b = $b->fetch();
3040                 }
3041                 return $b;
3042         }
3043
3044         public function setSessionOptions( array $options ) {
3045         }
3046
3047         public function sourceFile(
3048                 $filename,
3049                 callable $lineCallback = null,
3050                 callable $resultCallback = null,
3051                 $fname = false,
3052                 callable $inputCallback = null
3053         ) {
3054                 MediaWiki\suppressWarnings();
3055                 $fp = fopen( $filename, 'r' );
3056                 MediaWiki\restoreWarnings();
3057
3058                 if ( false === $fp ) {
3059                         throw new RuntimeException( "Could not open \"{$filename}\".\n" );
3060                 }
3061
3062                 if ( !$fname ) {
3063                         $fname = __METHOD__ . "( $filename )";
3064                 }
3065
3066                 try {
3067                         $error = $this->sourceStream(
3068                                 $fp, $lineCallback, $resultCallback, $fname, $inputCallback );
3069                 } catch ( Exception $e ) {
3070                         fclose( $fp );
3071                         throw $e;
3072                 }
3073
3074                 fclose( $fp );
3075
3076                 return $error;
3077         }
3078
3079         public function setSchemaVars( $vars ) {
3080                 $this->mSchemaVars = $vars;
3081         }
3082
3083         public function sourceStream(
3084                 $fp,
3085                 callable $lineCallback = null,
3086                 callable $resultCallback = null,
3087                 $fname = __METHOD__,
3088                 callable $inputCallback = null
3089         ) {
3090                 $cmd = '';
3091
3092                 while ( !feof( $fp ) ) {
3093                         if ( $lineCallback ) {
3094                                 call_user_func( $lineCallback );
3095                         }
3096
3097                         $line = trim( fgets( $fp ) );
3098
3099                         if ( $line == '' ) {
3100                                 continue;
3101                         }
3102
3103                         if ( '-' == $line[0] && '-' == $line[1] ) {
3104                                 continue;
3105                         }
3106
3107                         if ( $cmd != '' ) {
3108                                 $cmd .= ' ';
3109                         }
3110
3111                         $done = $this->streamStatementEnd( $cmd, $line );
3112
3113                         $cmd .= "$line\n";
3114
3115                         if ( $done || feof( $fp ) ) {
3116                                 $cmd = $this->replaceVars( $cmd );
3117
3118                                 if ( !$inputCallback || call_user_func( $inputCallback, $cmd ) ) {
3119                                         $res = $this->query( $cmd, $fname );
3120
3121                                         if ( $resultCallback ) {
3122                                                 call_user_func( $resultCallback, $res, $this );
3123                                         }
3124
3125                                         if ( false === $res ) {
3126                                                 $err = $this->lastError();
3127
3128                                                 return "Query \"{$cmd}\" failed with error code \"$err\".\n";
3129                                         }
3130                                 }
3131                                 $cmd = '';
3132                         }
3133                 }
3134
3135                 return true;
3136         }
3137
3138         /**
3139          * Called by sourceStream() to check if we've reached a statement end
3140          *
3141          * @param string &$sql SQL assembled so far
3142          * @param string &$newLine New line about to be added to $sql
3143          * @return bool Whether $newLine contains end of the statement
3144          */
3145         public function streamStatementEnd( &$sql, &$newLine ) {
3146                 if ( $this->delimiter ) {
3147                         $prev = $newLine;
3148                         $newLine = preg_replace(
3149                                 '/' . preg_quote( $this->delimiter, '/' ) . '$/', '', $newLine );
3150                         if ( $newLine != $prev ) {
3151                                 return true;
3152                         }
3153                 }
3154
3155                 return false;
3156         }
3157
3158         /**
3159          * Database independent variable replacement. Replaces a set of variables
3160          * in an SQL statement with their contents as given by $this->getSchemaVars().
3161          *
3162          * Supports '{$var}' `{$var}` and / *$var* / (without the spaces) style variables.
3163          *
3164          * - '{$var}' should be used for text and is passed through the database's
3165          *   addQuotes method.
3166          * - `{$var}` should be used for identifiers (e.g. table and database names).
3167          *   It is passed through the database's addIdentifierQuotes method which
3168          *   can be overridden if the database uses something other than backticks.
3169          * - / *_* / or / *$wgDBprefix* / passes the name that follows through the
3170          *   database's tableName method.
3171          * - / *i* / passes the name that follows through the database's indexName method.
3172          * - In all other cases, / *$var* / is left unencoded. Except for table options,
3173          *   its use should be avoided. In 1.24 and older, string encoding was applied.
3174          *
3175          * @param string $ins SQL statement to replace variables in
3176          * @return string The new SQL statement with variables replaced
3177          */
3178         protected function replaceVars( $ins ) {
3179                 $vars = $this->getSchemaVars();
3180                 return preg_replace_callback(
3181                         '!
3182                                 /\* (\$wgDBprefix|[_i]) \*/ (\w*) | # 1-2. tableName, indexName
3183                                 \'\{\$ (\w+) }\'                  | # 3. addQuotes
3184                                 `\{\$ (\w+) }`                    | # 4. addIdentifierQuotes
3185                                 /\*\$ (\w+) \*/                     # 5. leave unencoded
3186                         !x',
3187                         function ( $m ) use ( $vars ) {
3188                                 // Note: Because of <https://bugs.php.net/bug.php?id=51881>,
3189                                 // check for both nonexistent keys *and* the empty string.
3190                                 if ( isset( $m[1] ) && $m[1] !== '' ) {
3191                                         if ( $m[1] === 'i' ) {
3192                                                 return $this->indexName( $m[2] );
3193                                         } else {
3194                                                 return $this->tableName( $m[2] );
3195                                         }
3196                                 } elseif ( isset( $m[3] ) && $m[3] !== '' && array_key_exists( $m[3], $vars ) ) {
3197                                         return $this->addQuotes( $vars[$m[3]] );
3198                                 } elseif ( isset( $m[4] ) && $m[4] !== '' && array_key_exists( $m[4], $vars ) ) {
3199                                         return $this->addIdentifierQuotes( $vars[$m[4]] );
3200                                 } elseif ( isset( $m[5] ) && $m[5] !== '' && array_key_exists( $m[5], $vars ) ) {
3201                                         return $vars[$m[5]];
3202                                 } else {
3203                                         return $m[0];
3204                                 }
3205                         },
3206                         $ins
3207                 );
3208         }
3209
3210         /**
3211          * Get schema variables. If none have been set via setSchemaVars(), then
3212          * use some defaults from the current object.
3213          *
3214          * @return array
3215          */
3216         protected function getSchemaVars() {
3217                 if ( $this->mSchemaVars ) {
3218                         return $this->mSchemaVars;
3219                 } else {
3220                         return $this->getDefaultSchemaVars();
3221                 }
3222         }
3223
3224         /**
3225          * Get schema variables to use if none have been set via setSchemaVars().
3226          *
3227          * Override this in derived classes to provide variables for tables.sql
3228          * and SQL patch files.
3229          *
3230          * @return array
3231          */
3232         protected function getDefaultSchemaVars() {
3233                 return [];
3234         }
3235
3236         public function lockIsFree( $lockName, $method ) {
3237                 return true;
3238         }
3239
3240         public function lock( $lockName, $method, $timeout = 5 ) {
3241                 $this->mNamedLocksHeld[$lockName] = 1;
3242
3243                 return true;
3244         }
3245
3246         public function unlock( $lockName, $method ) {
3247                 unset( $this->mNamedLocksHeld[$lockName] );
3248
3249                 return true;
3250         }
3251
3252         public function getScopedLockAndFlush( $lockKey, $fname, $timeout ) {
3253                 if ( $this->writesOrCallbacksPending() ) {
3254                         // This only flushes transactions to clear snapshots, not to write data
3255                         $fnames = implode( ', ', $this->pendingWriteAndCallbackCallers() );
3256                         throw new DBUnexpectedError(
3257                                 $this,
3258                                 "$fname: Cannot COMMIT to clear snapshot because writes are pending ($fnames)."
3259                         );
3260                 }
3261
3262                 if ( !$this->lock( $lockKey, $fname, $timeout ) ) {
3263                         return null;
3264                 }
3265
3266                 $unlocker = new ScopedCallback( function () use ( $lockKey, $fname ) {
3267                         if ( $this->trxLevel() ) {
3268                                 // There is a good chance an exception was thrown, causing any early return
3269                                 // from the caller. Let any error handler get a chance to issue rollback().
3270                                 // If there isn't one, let the error bubble up and trigger server-side rollback.
3271                                 $this->onTransactionResolution(
3272                                         function () use ( $lockKey, $fname ) {
3273                                                 $this->unlock( $lockKey, $fname );
3274                                         },
3275                                         $fname
3276                                 );
3277                         } else {
3278                                 $this->unlock( $lockKey, $fname );
3279                         }
3280                 } );
3281
3282                 $this->commit( $fname, self::FLUSHING_INTERNAL );
3283
3284                 return $unlocker;
3285         }
3286
3287         public function namedLocksEnqueue() {
3288                 return false;
3289         }
3290
3291         /**
3292          * Lock specific tables
3293          *
3294          * @param array $read Array of tables to lock for read access
3295          * @param array $write Array of tables to lock for write access
3296          * @param string $method Name of caller
3297          * @param bool $lowPriority Whether to indicate writes to be LOW PRIORITY
3298          * @return bool
3299          */
3300         public function lockTables( $read, $write, $method, $lowPriority = true ) {
3301                 return true;
3302         }
3303
3304         /**
3305          * Unlock specific tables
3306          *
3307          * @param string $method The caller
3308          * @return bool
3309          */
3310         public function unlockTables( $method ) {
3311                 return true;
3312         }
3313
3314         /**
3315          * Delete a table
3316          * @param string $tableName
3317          * @param string $fName
3318          * @return bool|ResultWrapper
3319          * @since 1.18
3320          */
3321         public function dropTable( $tableName, $fName = __METHOD__ ) {
3322                 if ( !$this->tableExists( $tableName, $fName ) ) {
3323                         return false;
3324                 }
3325                 $sql = "DROP TABLE " . $this->tableName( $tableName ) . " CASCADE";
3326
3327                 return $this->query( $sql, $fName );
3328         }
3329
3330         public function getInfinity() {
3331                 return 'infinity';
3332         }
3333
3334         public function encodeExpiry( $expiry ) {
3335                 return ( $expiry == '' || $expiry == 'infinity' || $expiry == $this->getInfinity() )
3336                         ? $this->getInfinity()
3337                         : $this->timestamp( $expiry );
3338         }
3339
3340         public function decodeExpiry( $expiry, $format = TS_MW ) {
3341                 if ( $expiry == '' || $expiry == 'infinity' || $expiry == $this->getInfinity() ) {
3342                         return 'infinity';
3343                 }
3344
3345                 return ConvertibleTimestamp::convert( $format, $expiry );
3346         }
3347
3348         public function setBigSelects( $value = true ) {
3349                 // no-op
3350         }
3351
3352         public function isReadOnly() {
3353                 return ( $this->getReadOnlyReason() !== false );
3354         }
3355
3356         /**
3357          * @return string|bool Reason this DB is read-only or false if it is not
3358          */
3359         protected function getReadOnlyReason() {
3360                 $reason = $this->getLBInfo( 'readOnlyReason' );
3361
3362                 return is_string( $reason ) ? $reason : false;
3363         }
3364
3365         public function setTableAliases( array $aliases ) {
3366                 $this->tableAliases = $aliases;
3367         }
3368
3369         /**
3370          * @return bool Whether a DB user is required to access the DB
3371          * @since 1.28
3372          */
3373         protected function requiresDatabaseUser() {
3374                 return true;
3375         }
3376
3377         /**
3378          * @since 1.19
3379          * @return string
3380          */
3381         public function __toString() {
3382                 return (string)$this->mConn;
3383         }
3384
3385         /**
3386          * Make sure that copies do not share the same client binding handle
3387          * @throws DBConnectionError
3388          */
3389         public function __clone() {
3390                 $this->connLogger->warning(
3391                         "Cloning " . get_class( $this ) . " is not recomended; forking connection:\n" .
3392                         ( new RuntimeException() )->getTraceAsString()
3393                 );
3394
3395                 if ( $this->isOpen() ) {
3396                         // Open a new connection resource without messing with the old one
3397                         $this->mOpened = false;
3398                         $this->mConn = false;
3399                         $this->mTrxEndCallbacks = []; // don't copy
3400                         $this->handleSessionLoss(); // no trx or locks anymore
3401                         $this->open( $this->mServer, $this->mUser, $this->mPassword, $this->mDBname );
3402                         $this->lastPing = microtime( true );
3403                 }
3404         }
3405
3406         /**
3407          * Called by serialize. Throw an exception when DB connection is serialized.
3408          * This causes problems on some database engines because the connection is
3409          * not restored on unserialize.
3410          */
3411         public function __sleep() {
3412                 throw new RuntimeException( 'Database serialization may cause problems, since ' .
3413                         'the connection is not restored on wakeup.' );
3414         }
3415
3416         /**
3417          * Run a few simple sanity checks and close dangling connections
3418          */
3419         public function __destruct() {
3420                 if ( $this->mTrxLevel && $this->mTrxDoneWrites ) {
3421                         trigger_error( "Uncommitted DB writes (transaction from {$this->mTrxFname})." );
3422                 }
3423
3424                 $danglingWriters = $this->pendingWriteAndCallbackCallers();
3425                 if ( $danglingWriters ) {
3426                         $fnames = implode( ', ', $danglingWriters );
3427                         trigger_error( "DB transaction writes or callbacks still pending ($fnames)." );
3428                 }
3429
3430                 if ( $this->mConn ) {
3431                         // Avoid connection leaks for sanity
3432                         $this->closeConnection();
3433                         $this->mConn = false;
3434                         $this->mOpened = false;
3435                 }
3436         }
3437 }
3438
3439 class_alias( 'Database', 'DatabaseBase' );