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|null 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_USER_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                 return !in_array(
 783                         $this->getQueryVerb( $sql ),
 784                         [ 'BEGIN', 'COMMIT', 'ROLLBACK', 'SHOW', 'SET', 'CREATE', 'ALTER' ],
 785                         true
 786                 );
 787         }
 788
 789         /**
 790          * @param string $sql A SQL query
 791          * @return bool Whether $sql is SQL for creating/dropping a new TEMPORARY table
 792          */
 793         protected function registerTempTableOperation( $sql ) {
 794                 if ( preg_match(
 795                         '/^CREATE\s+TEMPORARY\s+TABLE\s+(?:IF\s+NOT\s+EXISTS\s+)?[`"\']?(\w+)[`"\']?/i',
 796                         $sql,
 797                         $matches
 798                 ) ) {
 799                         $this->mSessionTempTables[$matches[1]] = 1;
 800
 801                         return true;
 802                 } elseif ( preg_match(
 803                         '/^DROP\s+(?:TEMPORARY\s+)?TABLE\s+(?:IF\s+EXISTS\s+)?[`"\']?(\w+)[`"\']?/i',
 804                         $sql,
 805                         $matches
 806                 ) ) {
 807                         unset( $this->mSessionTempTables[$matches[1]] );
 808
 809                         return true;
 810                 } elseif ( preg_match(
 811                         '/^(?:INSERT\s+(?:\w+\s+)?INTO|UPDATE|DELETE\s+FROM)\s+[`"\']?(\w+)[`"\']?/i',
 812                         $sql,
 813                         $matches
 814                 ) ) {
 815                         return isset( $this->mSessionTempTables[$matches[1]] );
 816                 }
 817
 818                 return false;
 819         }
 820
 821         public function query( $sql, $fname = __METHOD__, $tempIgnore = false ) {
 822                 $priorWritesPending = $this->writesOrCallbacksPending();
 823                 $this->mLastQuery = $sql;
 824
 825                 $isWrite = $this->isWriteQuery( $sql ) && !$this->registerTempTableOperation( $sql );
 826                 if ( $isWrite ) {
 827                         $reason = $this->getReadOnlyReason();
 828                         if ( $reason !== false ) {
 829                                 throw new DBReadOnlyError( $this, "Database is read-only: $reason" );
 830                         }
 831                         # Set a flag indicating that writes have been done
 832                         $this->mLastWriteTime = microtime( true );
 833                 }
 834
 835                 // Add trace comment to the begin of the sql string, right after the operator.
 836                 // Or, for one-word queries (like "BEGIN" or COMMIT") add it to the end (bug 42598)
 837                 $commentedSql = preg_replace( '/\s|$/', " /* $fname {$this->agent} */ ", $sql, 1 );
 838
 839                 # Start implicit transactions that wrap the request if DBO_TRX is enabled
 840                 if ( !$this->mTrxLevel && $this->getFlag( self::DBO_TRX )
 841                         && $this->isTransactableQuery( $sql )
 842                 ) {
 843                         $this->begin( __METHOD__ . " ($fname)", self::TRANSACTION_INTERNAL );
 844                         $this->mTrxAutomatic = true;
 845                 }
 846
 847                 # Keep track of whether the transaction has write queries pending
 848                 if ( $this->mTrxLevel && !$this->mTrxDoneWrites && $isWrite ) {
 849                         $this->mTrxDoneWrites = true;
 850                         $this->trxProfiler->transactionWritingIn(
 851                                 $this->mServer, $this->mDBname, $this->mTrxShortId );
 852                 }
 853
 854                 if ( $this->getFlag( self::DBO_DEBUG ) ) {
 855                         $this->queryLogger->debug( "{$this->mDBname} {$commentedSql}" );
 856                 }
 857
 858                 # Avoid fatals if close() was called
 859                 $this->assertOpen();
 860
 861                 # Send the query to the server
 862                 $ret = $this->doProfiledQuery( $sql, $commentedSql, $isWrite, $fname );
 863
 864                 # Try reconnecting if the connection was lost
 865                 if ( false === $ret && $this->wasErrorReissuable() ) {
 866                         $recoverable = $this->canRecoverFromDisconnect( $sql, $priorWritesPending );
 867                         # Stash the last error values before anything might clear them
 868                         $lastError = $this->lastError();
 869                         $lastErrno = $this->lastErrno();
 870                         # Update state tracking to reflect transaction loss due to disconnection
 871                         $this->handleSessionLoss();
 872                         if ( $this->reconnect() ) {
 873                                 $msg = __METHOD__ . ": lost connection to {$this->getServer()}; reconnected";
 874                                 $this->connLogger->warning( $msg );
 875                                 $this->queryLogger->warning(
 876                                         "$msg:\n" . ( new RuntimeException() )->getTraceAsString() );
 877
 878                                 if ( !$recoverable ) {
 879                                         # Callers may catch the exception and continue to use the DB
 880                                         $this->reportQueryError( $lastError, $lastErrno, $sql, $fname );
 881                                 } else {
 882                                         # Should be safe to silently retry the query
 883                                         $ret = $this->doProfiledQuery( $sql, $commentedSql, $isWrite, $fname );
 884                                 }
 885                         } else {
 886                                 $msg = __METHOD__ . ": lost connection to {$this->getServer()} permanently";
 887                                 $this->connLogger->error( $msg );
 888                         }
 889                 }
 890
 891                 if ( false === $ret ) {
 892                         # Deadlocks cause the entire transaction to abort, not just the statement.
 893                         # http://dev.mysql.com/doc/refman/5.7/en/innodb-error-handling.html
 894                         # https://www.postgresql.org/docs/9.1/static/explicit-locking.html
 895                         if ( $this->wasDeadlock() ) {
 896                                 if ( $this->explicitTrxActive() || $priorWritesPending ) {
 897                                         $tempIgnore = false; // not recoverable
 898                                 }
 899                                 # Update state tracking to reflect transaction loss
 900                                 $this->handleSessionLoss();
 901                         }
 902
 903                         $this->reportQueryError(
 904                                 $this->lastError(), $this->lastErrno(), $sql, $fname, $tempIgnore );
 905                 }
 906
 907                 $res = $this->resultObject( $ret );
 908
 909                 return $res;
 910         }
 911
 912         private function doProfiledQuery( $sql, $commentedSql, $isWrite, $fname ) {
 913                 $isMaster = !is_null( $this->getLBInfo( 'master' ) );
 914                 # generalizeSQL() will probably cut down the query to reasonable
 915                 # logging size most of the time. The substr is really just a sanity check.
 916                 if ( $isMaster ) {
 917                         $queryProf = 'query-m: ' . substr( self::generalizeSQL( $sql ), 0, 255 );
 918                 } else {
 919                         $queryProf = 'query: ' . substr( self::generalizeSQL( $sql ), 0, 255 );
 920                 }
 921
 922                 # Include query transaction state
 923                 $queryProf .= $this->mTrxShortId ? " [TRX#{$this->mTrxShortId}]" : "";
 924
 925                 $startTime = microtime( true );
 926                 if ( $this->profiler ) {
 927                         call_user_func( [ $this->profiler, 'profileIn' ], $queryProf );
 928                 }
 929                 $ret = $this->doQuery( $commentedSql );
 930                 if ( $this->profiler ) {
 931                         call_user_func( [ $this->profiler, 'profileOut' ], $queryProf );
 932                 }
 933                 $queryRuntime = max( microtime( true ) - $startTime, 0.0 );
 934
 935                 unset( $queryProfSection ); // profile out (if set)
 936
 937                 if ( $ret !== false ) {
 938                         $this->lastPing = $startTime;
 939                         if ( $isWrite && $this->mTrxLevel ) {
 940                                 $this->updateTrxWriteQueryTime( $sql, $queryRuntime );
 941                                 $this->mTrxWriteCallers[] = $fname;
 942                         }
 943                 }
 944
 945                 if ( $sql === self::PING_QUERY ) {
 946                         $this->mRTTEstimate = $queryRuntime;
 947                 }
 948
 949                 $this->trxProfiler->recordQueryCompletion(
 950                         $queryProf, $startTime, $isWrite, $this->affectedRows()
 951                 );
 952                 $this->queryLogger->debug( $sql, [
 953                         'method' => $fname,
 954                         'master' => $isMaster,
 955                         'runtime' => $queryRuntime,
 956                 ] );
 957
 958                 return $ret;
 959         }
 960
 961         /**
 962          * Update the estimated run-time of a query, not counting large row lock times
 963          *
 964          * LoadBalancer can be set to rollback transactions that will create huge replication
 965          * lag. It bases this estimate off of pendingWriteQueryDuration(). Certain simple
 966          * queries, like inserting a row can take a long time due to row locking. This method
 967          * uses some simple heuristics to discount those cases.
 968          *
 969          * @param string $sql A SQL write query
 970          * @param float $runtime Total runtime, including RTT
 971          */
 972         private function updateTrxWriteQueryTime( $sql, $runtime ) {
 973                 // Whether this is indicative of replica DB runtime (except for RBR or ws_repl)
 974                 $indicativeOfReplicaRuntime = true;
 975                 if ( $runtime > self::SLOW_WRITE_SEC ) {
 976                         $verb = $this->getQueryVerb( $sql );
 977                         // insert(), upsert(), replace() are fast unless bulky in size or blocked on locks
 978                         if ( $verb === 'INSERT' ) {
 979                                 $indicativeOfReplicaRuntime = $this->affectedRows() > self::SMALL_WRITE_ROWS;
 980                         } elseif ( $verb === 'REPLACE' ) {
 981                                 $indicativeOfReplicaRuntime = $this->affectedRows() > self::SMALL_WRITE_ROWS / 2;
 982                         }
 983                 }
 984
 985                 $this->mTrxWriteDuration += $runtime;
 986                 $this->mTrxWriteQueryCount += 1;
 987                 if ( $indicativeOfReplicaRuntime ) {
 988                         $this->mTrxWriteAdjDuration += $runtime;
 989                         $this->mTrxWriteAdjQueryCount += 1;
 990                 }
 991         }
 992
 993         private function canRecoverFromDisconnect( $sql, $priorWritesPending ) {
 994                 # Transaction dropped; this can mean lost writes, or REPEATABLE-READ snapshots.
 995                 # Dropped connections also mean that named locks are automatically released.
 996                 # Only allow error suppression in autocommit mode or when the lost transaction
 997                 # didn't matter anyway (aside from DBO_TRX snapshot loss).
 998                 if ( $this->mNamedLocksHeld ) {
 999                         return false; // possible critical section violation
1000                 } elseif ( $sql === 'COMMIT' ) {
1001                         return !$priorWritesPending; // nothing written anyway? (T127428)
1002                 } elseif ( $sql === 'ROLLBACK' ) {
1003                         return true; // transaction lost...which is also what was requested :)
1004                 } elseif ( $this->explicitTrxActive() ) {
1005                         return false; // don't drop atomocity
1006                 } elseif ( $priorWritesPending ) {
1007                         return false; // prior writes lost from implicit transaction
1008                 }
1009
1010                 return true;
1011         }
1012
1013         private function handleSessionLoss() {
1014                 $this->mTrxLevel = 0;
1015                 $this->mTrxIdleCallbacks = []; // bug 65263
1016                 $this->mTrxPreCommitCallbacks = []; // bug 65263
1017                 $this->mSessionTempTables = [];
1018                 $this->mNamedLocksHeld = [];
1019                 try {
1020                         // Handle callbacks in mTrxEndCallbacks
1021                         $this->runOnTransactionIdleCallbacks( self::TRIGGER_ROLLBACK );
1022                         $this->runTransactionListenerCallbacks( self::TRIGGER_ROLLBACK );
1023                         return null;
1024                 } catch ( Exception $e ) {
1025                         // Already logged; move on...
1026                         return $e;
1027                 }
1028         }
1029
1030         public function reportQueryError( $error, $errno, $sql, $fname, $tempIgnore = false ) {
1031                 if ( $this->ignoreErrors() || $tempIgnore ) {
1032                         $this->queryLogger->debug( "SQL ERROR (ignored): $error\n" );
1033                 } else {
1034                         $sql1line = mb_substr( str_replace( "\n", "\\n", $sql ), 0, 5 * 1024 );
1035                         $this->queryLogger->error(
1036                                 "{fname}\t{db_server}\t{errno}\t{error}\t{sql1line}",
1037                                 $this->getLogContext( [
1038                                         'method' => __METHOD__,
1039                                         'errno' => $errno,
1040                                         'error' => $error,
1041                                         'sql1line' => $sql1line,
1042                                         'fname' => $fname,
1043                                 ] )
1044                         );
1045                         $this->queryLogger->debug( "SQL ERROR: " . $error . "\n" );
1046                         throw new DBQueryError( $this, $error, $errno, $sql, $fname );
1047                 }
1048         }
1049
1050         public function freeResult( $res ) {
1051         }
1052
1053         public function selectField(
1054                 $table, $var, $cond = '', $fname = __METHOD__, $options = []
1055         ) {
1056                 if ( $var === '*' ) { // sanity
1057                         throw new DBUnexpectedError( $this, "Cannot use a * field: got '$var'" );
1058                 }
1059
1060                 if ( !is_array( $options ) ) {
1061                         $options = [ $options ];
1062                 }
1063
1064                 $options['LIMIT'] = 1;
1065
1066                 $res = $this->select( $table, $var, $cond, $fname, $options );
1067                 if ( $res === false || !$this->numRows( $res ) ) {
1068                         return false;
1069                 }
1070
1071                 $row = $this->fetchRow( $res );
1072
1073                 if ( $row !== false ) {
1074                         return reset( $row );
1075                 } else {
1076                         return false;
1077                 }
1078         }
1079
1080         public function selectFieldValues(
1081                 $table, $var, $cond = '', $fname = __METHOD__, $options = [], $join_conds = []
1082         ) {
1083                 if ( $var === '*' ) { // sanity
1084                         throw new DBUnexpectedError( $this, "Cannot use a * field" );
1085                 } elseif ( !is_string( $var ) ) { // sanity
1086                         throw new DBUnexpectedError( $this, "Cannot use an array of fields" );
1087                 }
1088
1089                 if ( !is_array( $options ) ) {
1090                         $options = [ $options ];
1091                 }
1092
1093                 $res = $this->select( $table, $var, $cond, $fname, $options, $join_conds );
1094                 if ( $res === false ) {
1095                         return false;
1096                 }
1097
1098                 $values = [];
1099                 foreach ( $res as $row ) {
1100                         $values[] = $row->$var;
1101                 }
1102
1103                 return $values;
1104         }
1105
1106         /**
1107          * Returns an optional USE INDEX clause to go after the table, and a
1108          * string to go at the end of the query.
1109          *
1110          * @param array $options Associative array of options to be turned into
1111          *   an SQL query, valid keys are listed in the function.
1112          * @return array
1113          * @see Database::select()
1114          */
1115         protected function makeSelectOptions( $options ) {
1116                 $preLimitTail = $postLimitTail = '';
1117                 $startOpts = '';
1118
1119                 $noKeyOptions = [];
1120
1121                 foreach ( $options as $key => $option ) {
1122                         if ( is_numeric( $key ) ) {
1123                                 $noKeyOptions[$option] = true;
1124                         }
1125                 }
1126
1127                 $preLimitTail .= $this->makeGroupByWithHaving( $options );
1128
1129                 $preLimitTail .= $this->makeOrderBy( $options );
1130
1131                 // if (isset($options['LIMIT'])) {
1132                 //      $tailOpts .= $this->limitResult('', $options['LIMIT'],
1133                 //              isset($options['OFFSET']) ? $options['OFFSET']
1134                 //              : false);
1135                 // }
1136
1137                 if ( isset( $noKeyOptions['FOR UPDATE'] ) ) {
1138                         $postLimitTail .= ' FOR UPDATE';
1139                 }
1140
1141                 if ( isset( $noKeyOptions['LOCK IN SHARE MODE'] ) ) {
1142                         $postLimitTail .= ' LOCK IN SHARE MODE';
1143                 }
1144
1145                 if ( isset( $noKeyOptions['DISTINCT'] ) || isset( $noKeyOptions['DISTINCTROW'] ) ) {
1146                         $startOpts .= 'DISTINCT';
1147                 }
1148
1149                 # Various MySQL extensions
1150                 if ( isset( $noKeyOptions['STRAIGHT_JOIN'] ) ) {
1151                         $startOpts .= ' /*! STRAIGHT_JOIN */';
1152                 }
1153
1154                 if ( isset( $noKeyOptions['HIGH_PRIORITY'] ) ) {
1155                         $startOpts .= ' HIGH_PRIORITY';
1156                 }
1157
1158                 if ( isset( $noKeyOptions['SQL_BIG_RESULT'] ) ) {
1159                         $startOpts .= ' SQL_BIG_RESULT';
1160                 }
1161
1162                 if ( isset( $noKeyOptions['SQL_BUFFER_RESULT'] ) ) {
1163                         $startOpts .= ' SQL_BUFFER_RESULT';
1164                 }
1165
1166                 if ( isset( $noKeyOptions['SQL_SMALL_RESULT'] ) ) {
1167                         $startOpts .= ' SQL_SMALL_RESULT';
1168                 }
1169
1170                 if ( isset( $noKeyOptions['SQL_CALC_FOUND_ROWS'] ) ) {
1171                         $startOpts .= ' SQL_CALC_FOUND_ROWS';
1172                 }
1173
1174                 if ( isset( $noKeyOptions['SQL_CACHE'] ) ) {
1175                         $startOpts .= ' SQL_CACHE';
1176                 }
1177
1178                 if ( isset( $noKeyOptions['SQL_NO_CACHE'] ) ) {
1179                         $startOpts .= ' SQL_NO_CACHE';
1180                 }
1181
1182                 if ( isset( $options['USE INDEX'] ) && is_string( $options['USE INDEX'] ) ) {
1183                         $useIndex = $this->useIndexClause( $options['USE INDEX'] );
1184                 } else {
1185                         $useIndex = '';
1186                 }
1187                 if ( isset( $options['IGNORE INDEX'] ) && is_string( $options['IGNORE INDEX'] ) ) {
1188                         $ignoreIndex = $this->ignoreIndexClause( $options['IGNORE INDEX'] );
1189                 } else {
1190                         $ignoreIndex = '';
1191                 }
1192
1193                 return [ $startOpts, $useIndex, $preLimitTail, $postLimitTail, $ignoreIndex ];
1194         }
1195
1196         /**
1197          * Returns an optional GROUP BY with an optional HAVING
1198          *
1199          * @param array $options Associative array of options
1200          * @return string
1201          * @see Database::select()
1202          * @since 1.21
1203          */
1204         protected function makeGroupByWithHaving( $options ) {
1205                 $sql = '';
1206                 if ( isset( $options['GROUP BY'] ) ) {
1207                         $gb = is_array( $options['GROUP BY'] )
1208                                 ? implode( ',', $options['GROUP BY'] )
1209                                 : $options['GROUP BY'];
1210                         $sql .= ' GROUP BY ' . $gb;
1211                 }
1212                 if ( isset( $options['HAVING'] ) ) {
1213                         $having = is_array( $options['HAVING'] )
1214                                 ? $this->makeList( $options['HAVING'], self::LIST_AND )
1215                                 : $options['HAVING'];
1216                         $sql .= ' HAVING ' . $having;
1217                 }
1218
1219                 return $sql;
1220         }
1221
1222         /**
1223          * Returns an optional ORDER BY
1224          *
1225          * @param array $options Associative array of options
1226          * @return string
1227          * @see Database::select()
1228          * @since 1.21
1229          */
1230         protected function makeOrderBy( $options ) {
1231                 if ( isset( $options['ORDER BY'] ) ) {
1232                         $ob = is_array( $options['ORDER BY'] )
1233                                 ? implode( ',', $options['ORDER BY'] )
1234                                 : $options['ORDER BY'];
1235
1236                         return ' ORDER BY ' . $ob;
1237                 }
1238
1239                 return '';
1240         }
1241
1242         public function select( $table, $vars, $conds = '', $fname = __METHOD__,
1243                 $options = [], $join_conds = [] ) {
1244                 $sql = $this->selectSQLText( $table, $vars, $conds, $fname, $options, $join_conds );
1245
1246                 return $this->query( $sql, $fname );
1247         }
1248
1249         public function selectSQLText( $table, $vars, $conds = '', $fname = __METHOD__,
1250                 $options = [], $join_conds = []
1251         ) {
1252                 if ( is_array( $vars ) ) {
1253                         $vars = implode( ',', $this->fieldNamesWithAlias( $vars ) );
1254                 }
1255
1256                 $options = (array)$options;
1257                 $useIndexes = ( isset( $options['USE INDEX'] ) && is_array( $options['USE INDEX'] ) )
1258                         ? $options['USE INDEX']
1259                         : [];
1260                 $ignoreIndexes = (
1261                         isset( $options['IGNORE INDEX'] ) &&
1262                         is_array( $options['IGNORE INDEX'] )
1263                 )
1264                         ? $options['IGNORE INDEX']
1265                         : [];
1266
1267                 if ( is_array( $table ) ) {
1268                         $from = ' FROM ' .
1269                                 $this->tableNamesWithIndexClauseOrJOIN(
1270                                         $table, $useIndexes, $ignoreIndexes, $join_conds );
1271                 } elseif ( $table != '' ) {
1272                         if ( $table[0] == ' ' ) {
1273                                 $from = ' FROM ' . $table;
1274                         } else {
1275                                 $from = ' FROM ' .
1276                                         $this->tableNamesWithIndexClauseOrJOIN(
1277                                                 [ $table ], $useIndexes, $ignoreIndexes, [] );
1278                         }
1279                 } else {
1280                         $from = '';
1281                 }
1282
1283                 list( $startOpts, $useIndex, $preLimitTail, $postLimitTail, $ignoreIndex ) =
1284                         $this->makeSelectOptions( $options );
1285
1286                 if ( !empty( $conds ) ) {
1287                         if ( is_array( $conds ) ) {
1288                                 $conds = $this->makeList( $conds, self::LIST_AND );
1289                         }
1290                         $sql = "SELECT $startOpts $vars $from $useIndex $ignoreIndex " .
1291                                 "WHERE $conds $preLimitTail";
1292                 } else {
1293                         $sql = "SELECT $startOpts $vars $from $useIndex $ignoreIndex $preLimitTail";
1294                 }
1295
1296                 if ( isset( $options['LIMIT'] ) ) {
1297                         $sql = $this->limitResult( $sql, $options['LIMIT'],
1298                                 isset( $options['OFFSET'] ) ? $options['OFFSET'] : false );
1299                 }
1300                 $sql = "$sql $postLimitTail";
1301
1302                 if ( isset( $options['EXPLAIN'] ) ) {
1303                         $sql = 'EXPLAIN ' . $sql;
1304                 }
1305
1306                 return $sql;
1307         }
1308
1309         public function selectRow( $table, $vars, $conds, $fname = __METHOD__,
1310                 $options = [], $join_conds = []
1311         ) {
1312                 $options = (array)$options;
1313                 $options['LIMIT'] = 1;
1314                 $res = $this->select( $table, $vars, $conds, $fname, $options, $join_conds );
1315
1316                 if ( $res === false ) {
1317                         return false;
1318                 }
1319
1320                 if ( !$this->numRows( $res ) ) {
1321                         return false;
1322                 }
1323
1324                 $obj = $this->fetchObject( $res );
1325
1326                 return $obj;
1327         }
1328
1329         public function estimateRowCount(
1330                 $table, $vars = '*', $conds = '', $fname = __METHOD__, $options = []
1331         ) {
1332                 $rows = 0;
1333                 $res = $this->select( $table, [ 'rowcount' => 'COUNT(*)' ], $conds, $fname, $options );
1334
1335                 if ( $res ) {
1336                         $row = $this->fetchRow( $res );
1337                         $rows = ( isset( $row['rowcount'] ) ) ? (int)$row['rowcount'] : 0;
1338                 }
1339
1340                 return $rows;
1341         }
1342
1343         public function selectRowCount(
1344                 $tables, $vars = '*', $conds = '', $fname = __METHOD__, $options = [], $join_conds = []
1345         ) {
1346                 $rows = 0;
1347                 $sql = $this->selectSQLText( $tables, '1', $conds, $fname, $options, $join_conds );
1348                 $res = $this->query( "SELECT COUNT(*) AS rowcount FROM ($sql) tmp_count", $fname );
1349
1350                 if ( $res ) {
1351                         $row = $this->fetchRow( $res );
1352                         $rows = ( isset( $row['rowcount'] ) ) ? (int)$row['rowcount'] : 0;
1353                 }
1354
1355                 return $rows;
1356         }
1357
1358         /**
1359          * Removes most variables from an SQL query and replaces them with X or N for numbers.
1360          * It's only slightly flawed. Don't use for anything important.
1361          *
1362          * @param string $sql A SQL Query
1363          *
1364          * @return string
1365          */
1366         protected static function generalizeSQL( $sql ) {
1367                 # This does the same as the regexp below would do, but in such a way
1368                 # as to avoid crashing php on some large strings.
1369                 # $sql = preg_replace( "/'([^\\\\']|\\\\.)*'|\"([^\\\\\"]|\\\\.)*\"/", "'X'", $sql );
1370
1371                 $sql = str_replace( "\\\\", '', $sql );
1372                 $sql = str_replace( "\\'", '', $sql );
1373                 $sql = str_replace( "\\\"", '', $sql );
1374                 $sql = preg_replace( "/'.*'/s", "'X'", $sql );
1375                 $sql = preg_replace( '/".*"/s', "'X'", $sql );
1376
1377                 # All newlines, tabs, etc replaced by single space
1378                 $sql = preg_replace( '/\s+/', ' ', $sql );
1379
1380                 # All numbers => N,
1381                 # except the ones surrounded by characters, e.g. l10n
1382                 $sql = preg_replace( '/-?\d+(,-?\d+)+/s', 'N,...,N', $sql );
1383                 $sql = preg_replace( '/(?<![a-zA-Z])-?\d+(?![a-zA-Z])/s', 'N', $sql );
1384
1385                 return $sql;
1386         }
1387
1388         public function fieldExists( $table, $field, $fname = __METHOD__ ) {
1389                 $info = $this->fieldInfo( $table, $field );
1390
1391                 return (bool)$info;
1392         }
1393
1394         public function indexExists( $table, $index, $fname = __METHOD__ ) {
1395                 if ( !$this->tableExists( $table ) ) {
1396                         return null;
1397                 }
1398
1399                 $info = $this->indexInfo( $table, $index, $fname );
1400                 if ( is_null( $info ) ) {
1401                         return null;
1402                 } else {
1403                         return $info !== false;
1404                 }
1405         }
1406
1407         public function tableExists( $table, $fname = __METHOD__ ) {
1408                 $tableRaw = $this->tableName( $table, 'raw' );
1409                 if ( isset( $this->mSessionTempTables[$tableRaw] ) ) {
1410                         return true; // already known to exist
1411                 }
1412
1413                 $table = $this->tableName( $table );
1414                 $old = $this->ignoreErrors( true );
1415                 $res = $this->query( "SELECT 1 FROM $table LIMIT 1", $fname );
1416                 $this->ignoreErrors( $old );
1417
1418                 return (bool)$res;
1419         }
1420
1421         public function indexUnique( $table, $index ) {
1422                 $indexInfo = $this->indexInfo( $table, $index );
1423
1424                 if ( !$indexInfo ) {
1425                         return null;
1426                 }
1427
1428                 return !$indexInfo[0]->Non_unique;
1429         }
1430
1431         /**
1432          * Helper for Database::insert().
1433          *
1434          * @param array $options
1435          * @return string
1436          */
1437         protected function makeInsertOptions( $options ) {
1438                 return implode( ' ', $options );
1439         }
1440
1441         public function insert( $table, $a, $fname = __METHOD__, $options = [] ) {
1442                 # No rows to insert, easy just return now
1443                 if ( !count( $a ) ) {
1444                         return true;
1445                 }
1446
1447                 $table = $this->tableName( $table );
1448
1449                 if ( !is_array( $options ) ) {
1450                         $options = [ $options ];
1451                 }
1452
1453                 $fh = null;
1454                 if ( isset( $options['fileHandle'] ) ) {
1455                         $fh = $options['fileHandle'];
1456                 }
1457                 $options = $this->makeInsertOptions( $options );
1458
1459                 if ( isset( $a[0] ) && is_array( $a[0] ) ) {
1460                         $multi = true;
1461                         $keys = array_keys( $a[0] );
1462                 } else {
1463                         $multi = false;
1464                         $keys = array_keys( $a );
1465                 }
1466
1467                 $sql = 'INSERT ' . $options .
1468                         " INTO $table (" . implode( ',', $keys ) . ') VALUES ';
1469
1470                 if ( $multi ) {
1471                         $first = true;
1472                         foreach ( $a as $row ) {
1473                                 if ( $first ) {
1474                                         $first = false;
1475                                 } else {
1476                                         $sql .= ',';
1477                                 }
1478                                 $sql .= '(' . $this->makeList( $row ) . ')';
1479                         }
1480                 } else {
1481                         $sql .= '(' . $this->makeList( $a ) . ')';
1482                 }
1483
1484                 if ( $fh !== null && false === fwrite( $fh, $sql ) ) {
1485                         return false;
1486                 } elseif ( $fh !== null ) {
1487                         return true;
1488                 }
1489
1490                 return (bool)$this->query( $sql, $fname );
1491         }
1492
1493         /**
1494          * Make UPDATE options array for Database::makeUpdateOptions
1495          *
1496          * @param array $options
1497          * @return array
1498          */
1499         protected function makeUpdateOptionsArray( $options ) {
1500                 if ( !is_array( $options ) ) {
1501                         $options = [ $options ];
1502                 }
1503
1504                 $opts = [];
1505
1506                 if ( in_array( 'IGNORE', $options ) ) {
1507                         $opts[] = 'IGNORE';
1508                 }
1509
1510                 return $opts;
1511         }
1512
1513         /**
1514          * Make UPDATE options for the Database::update function
1515          *
1516          * @param array $options The options passed to Database::update
1517          * @return string
1518          */
1519         protected function makeUpdateOptions( $options ) {
1520                 $opts = $this->makeUpdateOptionsArray( $options );
1521
1522                 return implode( ' ', $opts );
1523         }
1524
1525         public function update( $table, $values, $conds, $fname = __METHOD__, $options = [] ) {
1526                 $table = $this->tableName( $table );
1527                 $opts = $this->makeUpdateOptions( $options );
1528                 $sql = "UPDATE $opts $table SET " . $this->makeList( $values, self::LIST_SET );
1529
1530                 if ( $conds !== [] && $conds !== '*' ) {
1531                         $sql .= " WHERE " . $this->makeList( $conds, self::LIST_AND );
1532                 }
1533
1534                 return $this->query( $sql, $fname );
1535         }
1536
1537         public function makeList( $a, $mode = self::LIST_COMMA ) {
1538                 if ( !is_array( $a ) ) {
1539                         throw new DBUnexpectedError( $this, __METHOD__ . ' called with incorrect parameters' );
1540                 }
1541
1542                 $first = true;
1543                 $list = '';
1544
1545                 foreach ( $a as $field => $value ) {
1546                         if ( !$first ) {
1547                                 if ( $mode == self::LIST_AND ) {
1548                                         $list .= ' AND ';
1549                                 } elseif ( $mode == self::LIST_OR ) {
1550                                         $list .= ' OR ';
1551                                 } else {
1552                                         $list .= ',';
1553                                 }
1554                         } else {
1555                                 $first = false;
1556                         }
1557
1558                         if ( ( $mode == self::LIST_AND || $mode == self::LIST_OR ) && is_numeric( $field ) ) {
1559                                 $list .= "($value)";
1560                         } elseif ( $mode == self::LIST_SET && is_numeric( $field ) ) {
1561                                 $list .= "$value";
1562                         } elseif (
1563                                 ( $mode == self::LIST_AND || $mode == self::LIST_OR ) && is_array( $value )
1564                         ) {
1565                                 // Remove null from array to be handled separately if found
1566                                 $includeNull = false;
1567                                 foreach ( array_keys( $value, null, true ) as $nullKey ) {
1568                                         $includeNull = true;
1569                                         unset( $value[$nullKey] );
1570                                 }
1571                                 if ( count( $value ) == 0 && !$includeNull ) {
1572                                         throw new InvalidArgumentException(
1573                                                 __METHOD__ . ": empty input for field $field" );
1574                                 } elseif ( count( $value ) == 0 ) {
1575                                         // only check if $field is null
1576                                         $list .= "$field IS NULL";
1577                                 } else {
1578                                         // IN clause contains at least one valid element
1579                                         if ( $includeNull ) {
1580                                                 // Group subconditions to ensure correct precedence
1581                                                 $list .= '(';
1582                                         }
1583                                         if ( count( $value ) == 1 ) {
1584                                                 // Special-case single values, as IN isn't terribly efficient
1585                                                 // Don't necessarily assume the single key is 0; we don't
1586                                                 // enforce linear numeric ordering on other arrays here.
1587                                                 $value = array_values( $value )[0];
1588                                                 $list .= $field . " = " . $this->addQuotes( $value );
1589                                         } else {
1590                                                 $list .= $field . " IN (" . $this->makeList( $value ) . ") ";
1591                                         }
1592                                         // if null present in array, append IS NULL
1593                                         if ( $includeNull ) {
1594                                                 $list .= " OR $field IS NULL)";
1595                                         }
1596                                 }
1597                         } elseif ( $value === null ) {
1598                                 if ( $mode == self::LIST_AND || $mode == self::LIST_OR ) {
1599                                         $list .= "$field IS ";
1600                                 } elseif ( $mode == self::LIST_SET ) {
1601                                         $list .= "$field = ";
1602                                 }
1603                                 $list .= 'NULL';
1604                         } else {
1605                                 if (
1606                                         $mode == self::LIST_AND || $mode == self::LIST_OR || $mode == self::LIST_SET
1607                                 ) {
1608                                         $list .= "$field = ";
1609                                 }
1610                                 $list .= $mode == self::LIST_NAMES ? $value : $this->addQuotes( $value );
1611                         }
1612                 }
1613
1614                 return $list;
1615         }
1616
1617         public function makeWhereFrom2d( $data, $baseKey, $subKey ) {
1618                 $conds = [];
1619
1620                 foreach ( $data as $base => $sub ) {
1621                         if ( count( $sub ) ) {
1622                                 $conds[] = $this->makeList(
1623                                         [ $baseKey => $base, $subKey => array_keys( $sub ) ],
1624                                         self::LIST_AND );
1625                         }
1626                 }
1627
1628                 if ( $conds ) {
1629                         return $this->makeList( $conds, self::LIST_OR );
1630                 } else {
1631                         // Nothing to search for...
1632                         return false;
1633                 }
1634         }
1635
1636         public function aggregateValue( $valuedata, $valuename = 'value' ) {
1637                 return $valuename;
1638         }
1639
1640         public function bitNot( $field ) {
1641                 return "(~$field)";
1642         }
1643
1644         public function bitAnd( $fieldLeft, $fieldRight ) {
1645                 return "($fieldLeft & $fieldRight)";
1646         }
1647
1648         public function bitOr( $fieldLeft, $fieldRight ) {
1649                 return "($fieldLeft | $fieldRight)";
1650         }
1651
1652         public function buildConcat( $stringList ) {
1653                 return 'CONCAT(' . implode( ',', $stringList ) . ')';
1654         }
1655
1656         public function buildGroupConcatField(
1657                 $delim, $table, $field, $conds = '', $join_conds = []
1658         ) {
1659                 $fld = "GROUP_CONCAT($field SEPARATOR " . $this->addQuotes( $delim ) . ')';
1660
1661                 return '(' . $this->selectSQLText( $table, $fld, $conds, null, [], $join_conds ) . ')';
1662         }
1663
1664         public function buildStringCast( $field ) {
1665                 return $field;
1666         }
1667
1668         public function selectDB( $db ) {
1669                 # Stub. Shouldn't cause serious problems if it's not overridden, but
1670                 # if your database engine supports a concept similar to MySQL's
1671                 # databases you may as well.
1672                 $this->mDBname = $db;
1673
1674                 return true;
1675         }
1676
1677         public function getDBname() {
1678                 return $this->mDBname;
1679         }
1680
1681         public function getServer() {
1682                 return $this->mServer;
1683         }
1684
1685         public function tableName( $name, $format = 'quoted' ) {
1686                 # Skip the entire process when we have a string quoted on both ends.
1687                 # Note that we check the end so that we will still quote any use of
1688                 # use of `database`.table. But won't break things if someone wants
1689                 # to query a database table with a dot in the name.
1690                 if ( $this->isQuotedIdentifier( $name ) ) {
1691                         return $name;
1692                 }
1693
1694                 # Lets test for any bits of text that should never show up in a table
1695                 # name. Basically anything like JOIN or ON which are actually part of
1696                 # SQL queries, but may end up inside of the table value to combine
1697                 # sql. Such as how the API is doing.
1698                 # Note that we use a whitespace test rather than a \b test to avoid
1699                 # any remote case where a word like on may be inside of a table name
1700                 # surrounded by symbols which may be considered word breaks.
1701                 if ( preg_match( '/(^|\s)(DISTINCT|JOIN|ON|AS)(\s|$)/i', $name ) !== 0 ) {
1702                         return $name;
1703                 }
1704
1705                 # Split database and table into proper variables.
1706                 # We reverse the explode so that database.table and table both output
1707                 # the correct table.
1708                 $dbDetails = explode( '.', $name, 3 );
1709                 if ( count( $dbDetails ) == 3 ) {
1710                         list( $database, $schema, $table ) = $dbDetails;
1711                         # We don't want any prefix added in this case
1712                         $prefix = '';
1713                 } elseif ( count( $dbDetails ) == 2 ) {
1714                         list( $database, $table ) = $dbDetails;
1715                         # We don't want any prefix added in this case
1716                         # In dbs that support it, $database may actually be the schema
1717                         # but that doesn't affect any of the functionality here
1718                         $prefix = '';
1719                         $schema = '';
1720                 } else {
1721                         list( $table ) = $dbDetails;
1722                         if ( isset( $this->tableAliases[$table] ) ) {
1723                                 $database = $this->tableAliases[$table]['dbname'];
1724                                 $schema = is_string( $this->tableAliases[$table]['schema'] )
1725                                         ? $this->tableAliases[$table]['schema']
1726                                         : $this->mSchema;
1727                                 $prefix = is_string( $this->tableAliases[$table]['prefix'] )
1728                                         ? $this->tableAliases[$table]['prefix']
1729                                         : $this->mTablePrefix;
1730                         } else {
1731                                 $database = '';
1732                                 $schema = $this->mSchema; # Default schema
1733                                 $prefix = $this->mTablePrefix; # Default prefix
1734                         }
1735                 }
1736
1737                 # Quote $table and apply the prefix if not quoted.
1738                 # $tableName might be empty if this is called from Database::replaceVars()
1739                 $tableName = "{$prefix}{$table}";
1740                 if ( $format == 'quoted'
1741                         && !$this->isQuotedIdentifier( $tableName ) && $tableName !== ''
1742                 ) {
1743                         $tableName = $this->addIdentifierQuotes( $tableName );
1744                 }
1745
1746                 # Quote $schema and merge it with the table name if needed
1747                 if ( strlen( $schema ) ) {
1748                         if ( $format == 'quoted' && !$this->isQuotedIdentifier( $schema ) ) {
1749                                 $schema = $this->addIdentifierQuotes( $schema );
1750                         }
1751                         $tableName = $schema . '.' . $tableName;
1752                 }
1753
1754                 # Quote $database and merge it with the table name if needed
1755                 if ( $database !== '' ) {
1756                         if ( $format == 'quoted' && !$this->isQuotedIdentifier( $database ) ) {
1757                                 $database = $this->addIdentifierQuotes( $database );
1758                         }
1759                         $tableName = $database . '.' . $tableName;
1760                 }
1761
1762                 return $tableName;
1763         }
1764
1765         public function tableNames() {
1766                 $inArray = func_get_args();
1767                 $retVal = [];
1768
1769                 foreach ( $inArray as $name ) {
1770                         $retVal[$name] = $this->tableName( $name );
1771                 }
1772
1773                 return $retVal;
1774         }
1775
1776         public function tableNamesN() {
1777                 $inArray = func_get_args();
1778                 $retVal = [];
1779
1780                 foreach ( $inArray as $name ) {
1781                         $retVal[] = $this->tableName( $name );
1782                 }
1783
1784                 return $retVal;
1785         }
1786
1787         /**
1788          * Get an aliased table name
1789          * e.g. tableName AS newTableName
1790          *
1791          * @param string $name Table name, see tableName()
1792          * @param string|bool $alias Alias (optional)
1793          * @return string SQL name for aliased table. Will not alias a table to its own name
1794          */
1795         protected function tableNameWithAlias( $name, $alias = false ) {
1796                 if ( !$alias || $alias == $name ) {
1797                         return $this->tableName( $name );
1798                 } else {
1799                         return $this->tableName( $name ) . ' ' . $this->addIdentifierQuotes( $alias );
1800                 }
1801         }
1802
1803         /**
1804          * Gets an array of aliased table names
1805          *
1806          * @param array $tables [ [alias] => table ]
1807          * @return string[] See tableNameWithAlias()
1808          */
1809         protected function tableNamesWithAlias( $tables ) {
1810                 $retval = [];
1811                 foreach ( $tables as $alias => $table ) {
1812                         if ( is_numeric( $alias ) ) {
1813                                 $alias = $table;
1814                         }
1815                         $retval[] = $this->tableNameWithAlias( $table, $alias );
1816                 }
1817
1818                 return $retval;
1819         }
1820
1821         /**
1822          * Get an aliased field name
1823          * e.g. fieldName AS newFieldName
1824          *
1825          * @param string $name Field name
1826          * @param string|bool $alias Alias (optional)
1827          * @return string SQL name for aliased field. Will not alias a field to its own name
1828          */
1829         protected function fieldNameWithAlias( $name, $alias = false ) {
1830                 if ( !$alias || (string)$alias === (string)$name ) {
1831                         return $name;
1832                 } else {
1833                         return $name . ' AS ' . $this->addIdentifierQuotes( $alias ); // PostgreSQL needs AS
1834                 }
1835         }
1836
1837         /**
1838          * Gets an array of aliased field names
1839          *
1840          * @param array $fields [ [alias] => field ]
1841          * @return string[] See fieldNameWithAlias()
1842          */
1843         protected function fieldNamesWithAlias( $fields ) {
1844                 $retval = [];
1845                 foreach ( $fields as $alias => $field ) {
1846                         if ( is_numeric( $alias ) ) {
1847                                 $alias = $field;
1848                         }
1849                         $retval[] = $this->fieldNameWithAlias( $field, $alias );
1850                 }
1851
1852                 return $retval;
1853         }
1854
1855         /**
1856          * Get the aliased table name clause for a FROM clause
1857          * which might have a JOIN and/or USE INDEX or IGNORE INDEX clause
1858          *
1859          * @param array $tables ( [alias] => table )
1860          * @param array $use_index Same as for select()
1861          * @param array $ignore_index Same as for select()
1862          * @param array $join_conds Same as for select()
1863          * @return string
1864          */
1865         protected function tableNamesWithIndexClauseOrJOIN(
1866                 $tables, $use_index = [], $ignore_index = [], $join_conds = []
1867         ) {
1868                 $ret = [];
1869                 $retJOIN = [];
1870                 $use_index = (array)$use_index;
1871                 $ignore_index = (array)$ignore_index;
1872                 $join_conds = (array)$join_conds;
1873
1874                 foreach ( $tables as $alias => $table ) {
1875                         if ( !is_string( $alias ) ) {
1876                                 // No alias? Set it equal to the table name
1877                                 $alias = $table;
1878                         }
1879                         // Is there a JOIN clause for this table?
1880                         if ( isset( $join_conds[$alias] ) ) {
1881                                 list( $joinType, $conds ) = $join_conds[$alias];
1882                                 $tableClause = $joinType;
1883                                 $tableClause .= ' ' . $this->tableNameWithAlias( $table, $alias );
1884                                 if ( isset( $use_index[$alias] ) ) { // has USE INDEX?
1885                                         $use = $this->useIndexClause( implode( ',', (array)$use_index[$alias] ) );
1886                                         if ( $use != '' ) {
1887                                                 $tableClause .= ' ' . $use;
1888                                         }
1889                                 }
1890                                 if ( isset( $ignore_index[$alias] ) ) { // has IGNORE INDEX?
1891                                         $ignore = $this->ignoreIndexClause(
1892                                                 implode( ',', (array)$ignore_index[$alias] ) );
1893                                         if ( $ignore != '' ) {
1894                                                 $tableClause .= ' ' . $ignore;
1895                                         }
1896                                 }
1897                                 $on = $this->makeList( (array)$conds, self::LIST_AND );
1898                                 if ( $on != '' ) {
1899                                         $tableClause .= ' ON (' . $on . ')';
1900                                 }
1901
1902                                 $retJOIN[] = $tableClause;
1903                         } elseif ( isset( $use_index[$alias] ) ) {
1904                                 // Is there an INDEX clause for this table?
1905                                 $tableClause = $this->tableNameWithAlias( $table, $alias );
1906                                 $tableClause .= ' ' . $this->useIndexClause(
1907                                                 implode( ',', (array)$use_index[$alias] )
1908                                         );
1909
1910                                 $ret[] = $tableClause;
1911                         } elseif ( isset( $ignore_index[$alias] ) ) {
1912                                 // Is there an INDEX clause for this table?
1913                                 $tableClause = $this->tableNameWithAlias( $table, $alias );
1914                                 $tableClause .= ' ' . $this->ignoreIndexClause(
1915                                                 implode( ',', (array)$ignore_index[$alias] )
1916                                         );
1917
1918                                 $ret[] = $tableClause;
1919                         } else {
1920                                 $tableClause = $this->tableNameWithAlias( $table, $alias );
1921
1922                                 $ret[] = $tableClause;
1923                         }
1924                 }
1925
1926                 // We can't separate explicit JOIN clauses with ',', use ' ' for those
1927                 $implicitJoins = !empty( $ret ) ? implode( ',', $ret ) : "";
1928                 $explicitJoins = !empty( $retJOIN ) ? implode( ' ', $retJOIN ) : "";
1929
1930                 // Compile our final table clause
1931                 return implode( ' ', [ $implicitJoins, $explicitJoins ] );
1932         }
1933
1934         /**
1935          * Get the name of an index in a given table.
1936          *
1937          * @param string $index
1938          * @return string
1939          */
1940         protected function indexName( $index ) {
1941                 return $index;
1942         }
1943
1944         public function addQuotes( $s ) {
1945                 if ( $s instanceof Blob ) {
1946                         $s = $s->fetch();
1947                 }
1948                 if ( $s === null ) {
1949                         return 'NULL';
1950                 } elseif ( is_bool( $s ) ) {
1951                         return (int)$s;
1952                 } else {
1953                         # This will also quote numeric values. This should be harmless,
1954                         # and protects against weird problems that occur when they really
1955                         # _are_ strings such as article titles and string->number->string
1956                         # conversion is not 1:1.
1957                         return "'" . $this->strencode( $s ) . "'";
1958                 }
1959         }
1960
1961         /**
1962          * Quotes an identifier using `backticks` or "double quotes" depending on the database type.
1963          * MySQL uses `backticks` while basically everything else uses double quotes.
1964          * Since MySQL is the odd one out here the double quotes are our generic
1965          * and we implement backticks in DatabaseMysql.
1966          *
1967          * @param string $s
1968          * @return string
1969          */
1970         public function addIdentifierQuotes( $s ) {
1971                 return '"' . str_replace( '"', '""', $s ) . '"';
1972         }
1973
1974         /**
1975          * Returns if the given identifier looks quoted or not according to
1976          * the database convention for quoting identifiers .
1977          *
1978          * @note Do not use this to determine if untrusted input is safe.
1979          *   A malicious user can trick this function.
1980          * @param string $name
1981          * @return bool
1982          */
1983         public function isQuotedIdentifier( $name ) {
1984                 return $name[0] == '"' && substr( $name, -1, 1 ) == '"';
1985         }
1986
1987         /**
1988          * @param string $s
1989          * @return string
1990          */
1991         protected function escapeLikeInternal( $s ) {
1992                 return addcslashes( $s, '\%_' );
1993         }
1994
1995         public function buildLike() {
1996                 $params = func_get_args();
1997
1998                 if ( count( $params ) > 0 && is_array( $params[0] ) ) {
1999                         $params = $params[0];
2000                 }
2001
2002                 $s = '';
2003
2004                 foreach ( $params as $value ) {
2005                         if ( $value instanceof LikeMatch ) {
2006                                 $s .= $value->toString();
2007                         } else {
2008                                 $s .= $this->escapeLikeInternal( $value );
2009                         }
2010                 }
2011
2012                 return " LIKE {$this->addQuotes( $s )} ";
2013         }
2014
2015         public function anyChar() {
2016                 return new LikeMatch( '_' );
2017         }
2018
2019         public function anyString() {
2020                 return new LikeMatch( '%' );
2021         }
2022
2023         public function nextSequenceValue( $seqName ) {
2024                 return null;
2025         }
2026
2027         /**
2028          * USE INDEX clause. Unlikely to be useful for anything but MySQL. This
2029          * is only needed because a) MySQL must be as efficient as possible due to
2030          * its use on Wikipedia, and b) MySQL 4.0 is kind of dumb sometimes about
2031          * which index to pick. Anyway, other databases might have different
2032          * indexes on a given table. So don't bother overriding this unless you're
2033          * MySQL.
2034          * @param string $index
2035          * @return string
2036          */
2037         public function useIndexClause( $index ) {
2038                 return '';
2039         }
2040
2041         /**
2042          * IGNORE INDEX clause. Unlikely to be useful for anything but MySQL. This
2043          * is only needed because a) MySQL must be as efficient as possible due to
2044          * its use on Wikipedia, and b) MySQL 4.0 is kind of dumb sometimes about
2045          * which index to pick. Anyway, other databases might have different
2046          * indexes on a given table. So don't bother overriding this unless you're
2047          * MySQL.
2048          * @param string $index
2049          * @return string
2050          */
2051         public function ignoreIndexClause( $index ) {
2052                 return '';
2053         }
2054
2055         public function replace( $table, $uniqueIndexes, $rows, $fname = __METHOD__ ) {
2056                 $quotedTable = $this->tableName( $table );
2057
2058                 if ( count( $rows ) == 0 ) {
2059                         return;
2060                 }
2061
2062                 # Single row case
2063                 if ( !is_array( reset( $rows ) ) ) {
2064                         $rows = [ $rows ];
2065                 }
2066
2067                 // @FXIME: this is not atomic, but a trx would break affectedRows()
2068                 foreach ( $rows as $row ) {
2069                         # Delete rows which collide
2070                         if ( $uniqueIndexes ) {
2071                                 $sql = "DELETE FROM $quotedTable WHERE ";
2072                                 $first = true;
2073                                 foreach ( $uniqueIndexes as $index ) {
2074                                         if ( $first ) {
2075                                                 $first = false;
2076                                                 $sql .= '( ';
2077                                         } else {
2078                                                 $sql .= ' ) OR ( ';
2079                                         }
2080                                         if ( is_array( $index ) ) {
2081                                                 $first2 = true;
2082                                                 foreach ( $index as $col ) {
2083                                                         if ( $first2 ) {
2084                                                                 $first2 = false;
2085                                                         } else {
2086                                                                 $sql .= ' AND ';
2087                                                         }
2088                                                         $sql .= $col . '=' . $this->addQuotes( $row[$col] );
2089                                                 }
2090                                         } else {
2091                                                 $sql .= $index . '=' . $this->addQuotes( $row[$index] );
2092                                         }
2093                                 }
2094                                 $sql .= ' )';
2095                                 $this->query( $sql, $fname );
2096                         }
2097
2098                         # Now insert the row
2099                         $this->insert( $table, $row, $fname );
2100                 }
2101         }
2102
2103         /**
2104          * REPLACE query wrapper for MySQL and SQLite, which have a native REPLACE
2105          * statement.
2106          *
2107          * @param string $table Table name
2108          * @param array|string $rows Row(s) to insert
2109          * @param string $fname Caller function name
2110          *
2111          * @return ResultWrapper
2112          */
2113         protected function nativeReplace( $table, $rows, $fname ) {
2114                 $table = $this->tableName( $table );
2115
2116                 # Single row case
2117                 if ( !is_array( reset( $rows ) ) ) {
2118                         $rows = [ $rows ];
2119                 }
2120
2121                 $sql = "REPLACE INTO $table (" . implode( ',', array_keys( $rows[0] ) ) . ') VALUES ';
2122                 $first = true;
2123
2124                 foreach ( $rows as $row ) {
2125                         if ( $first ) {
2126                                 $first = false;
2127                         } else {
2128                                 $sql .= ',';
2129                         }
2130
2131                         $sql .= '(' . $this->makeList( $row ) . ')';
2132                 }
2133
2134                 return $this->query( $sql, $fname );
2135         }
2136
2137         public function upsert( $table, array $rows, array $uniqueIndexes, array $set,
2138                 $fname = __METHOD__
2139         ) {
2140                 if ( !count( $rows ) ) {
2141                         return true; // nothing to do
2142                 }
2143
2144                 if ( !is_array( reset( $rows ) ) ) {
2145                         $rows = [ $rows ];
2146                 }
2147
2148                 if ( count( $uniqueIndexes ) ) {
2149                         $clauses = []; // list WHERE clauses that each identify a single row
2150                         foreach ( $rows as $row ) {
2151                                 foreach ( $uniqueIndexes as $index ) {
2152                                         $index = is_array( $index ) ? $index : [ $index ]; // columns
2153                                         $rowKey = []; // unique key to this row
2154                                         foreach ( $index as $column ) {
2155                                                 $rowKey[$column] = $row[$column];
2156                                         }
2157                                         $clauses[] = $this->makeList( $rowKey, self::LIST_AND );
2158                                 }
2159                         }
2160                         $where = [ $this->makeList( $clauses, self::LIST_OR ) ];
2161                 } else {
2162                         $where = false;
2163                 }
2164
2165                 $useTrx = !$this->mTrxLevel;
2166                 if ( $useTrx ) {
2167                         $this->begin( $fname, self::TRANSACTION_INTERNAL );
2168                 }
2169                 try {
2170                         # Update any existing conflicting row(s)
2171                         if ( $where !== false ) {
2172                                 $ok = $this->update( $table, $set, $where, $fname );
2173                         } else {
2174                                 $ok = true;
2175                         }
2176                         # Now insert any non-conflicting row(s)
2177                         $ok = $this->insert( $table, $rows, $fname, [ 'IGNORE' ] ) && $ok;
2178                 } catch ( Exception $e ) {
2179                         if ( $useTrx ) {
2180                                 $this->rollback( $fname, self::FLUSHING_INTERNAL );
2181                         }
2182                         throw $e;
2183                 }
2184                 if ( $useTrx ) {
2185                         $this->commit( $fname, self::FLUSHING_INTERNAL );
2186                 }
2187
2188                 return $ok;
2189         }
2190
2191         public function deleteJoin( $delTable, $joinTable, $delVar, $joinVar, $conds,
2192                 $fname = __METHOD__
2193         ) {
2194                 if ( !$conds ) {
2195                         throw new DBUnexpectedError( $this, __METHOD__ . ' called with empty $conds' );
2196                 }
2197
2198                 $delTable = $this->tableName( $delTable );
2199                 $joinTable = $this->tableName( $joinTable );
2200                 $sql = "DELETE FROM $delTable WHERE $delVar IN (SELECT $joinVar FROM $joinTable ";
2201                 if ( $conds != '*' ) {
2202                         $sql .= 'WHERE ' . $this->makeList( $conds, self::LIST_AND );
2203                 }
2204                 $sql .= ')';
2205
2206                 $this->query( $sql, $fname );
2207         }
2208
2209         public function textFieldSize( $table, $field ) {
2210                 $table = $this->tableName( $table );
2211                 $sql = "SHOW COLUMNS FROM $table LIKE \"$field\";";
2212                 $res = $this->query( $sql, __METHOD__ );
2213                 $row = $this->fetchObject( $res );
2214
2215                 $m = [];
2216
2217                 if ( preg_match( '/\((.*)\)/', $row->Type, $m ) ) {
2218                         $size = $m[1];
2219                 } else {
2220                         $size = -1;
2221                 }
2222
2223                 return $size;
2224         }
2225
2226         public function delete( $table, $conds, $fname = __METHOD__ ) {
2227                 if ( !$conds ) {
2228                         throw new DBUnexpectedError( $this, __METHOD__ . ' called with no conditions' );
2229                 }
2230
2231                 $table = $this->tableName( $table );
2232                 $sql = "DELETE FROM $table";
2233
2234                 if ( $conds != '*' ) {
2235                         if ( is_array( $conds ) ) {
2236                                 $conds = $this->makeList( $conds, self::LIST_AND );
2237                         }
2238                         $sql .= ' WHERE ' . $conds;
2239                 }
2240
2241                 return $this->query( $sql, $fname );
2242         }
2243
2244         public function insertSelect(
2245                 $destTable, $srcTable, $varMap, $conds,
2246                 $fname = __METHOD__, $insertOptions = [], $selectOptions = []
2247         ) {
2248                 if ( $this->cliMode ) {
2249                         // For massive migrations with downtime, we don't want to select everything
2250                         // into memory and OOM, so do all this native on the server side if possible.
2251                         return $this->nativeInsertSelect(
2252                                 $destTable,
2253                                 $srcTable,
2254                                 $varMap,
2255                                 $conds,
2256                                 $fname,
2257                                 $insertOptions,
2258                                 $selectOptions
2259                         );
2260                 }
2261
2262                 // For web requests, do a locking SELECT and then INSERT. This puts the SELECT burden
2263                 // on only the master (without needing row-based-replication). It also makes it easy to
2264                 // know how big the INSERT is going to be.
2265                 $fields = [];
2266                 foreach ( $varMap as $dstColumn => $sourceColumnOrSql ) {
2267                         $fields[] = $this->fieldNameWithAlias( $sourceColumnOrSql, $dstColumn );
2268                 }
2269                 $selectOptions[] = 'FOR UPDATE';
2270                 $res = $this->select( $srcTable, implode( ',', $fields ), $conds, $fname, $selectOptions );
2271                 if ( !$res ) {
2272                         return false;
2273                 }
2274
2275                 $rows = [];
2276                 foreach ( $res as $row ) {
2277                         $rows[] = (array)$row;
2278                 }
2279
2280                 return $this->insert( $destTable, $rows, $fname, $insertOptions );
2281         }
2282
2283         protected function nativeInsertSelect( $destTable, $srcTable, $varMap, $conds,
2284                 $fname = __METHOD__,
2285                 $insertOptions = [], $selectOptions = []
2286         ) {
2287                 $destTable = $this->tableName( $destTable );
2288
2289                 if ( !is_array( $insertOptions ) ) {
2290                         $insertOptions = [ $insertOptions ];
2291                 }
2292
2293                 $insertOptions = $this->makeInsertOptions( $insertOptions );
2294
2295                 if ( !is_array( $selectOptions ) ) {
2296                         $selectOptions = [ $selectOptions ];
2297                 }
2298
2299                 list( $startOpts, $useIndex, $tailOpts, $ignoreIndex ) = $this->makeSelectOptions(
2300                         $selectOptions );
2301
2302                 if ( is_array( $srcTable ) ) {
2303                         $srcTable = implode( ',', array_map( [ &$this, 'tableName' ], $srcTable ) );
2304                 } else {
2305                         $srcTable = $this->tableName( $srcTable );
2306                 }
2307
2308                 $sql = "INSERT $insertOptions" .
2309                         " INTO $destTable (" . implode( ',', array_keys( $varMap ) ) . ')' .
2310                         " SELECT $startOpts " . implode( ',', $varMap ) .
2311                         " FROM $srcTable $useIndex $ignoreIndex ";
2312
2313                 if ( $conds != '*' ) {
2314                         if ( is_array( $conds ) ) {
2315                                 $conds = $this->makeList( $conds, self::LIST_AND );
2316                         }
2317                         $sql .= " WHERE $conds";
2318                 }
2319
2320                 $sql .= " $tailOpts";
2321
2322                 return $this->query( $sql, $fname );
2323         }
2324
2325         /**
2326          * Construct a LIMIT query with optional offset. This is used for query
2327          * pages. The SQL should be adjusted so that only the first $limit rows
2328          * are returned. If $offset is provided as well, then the first $offset
2329          * rows should be discarded, and the next $limit rows should be returned.
2330          * If the result of the query is not ordered, then the rows to be returned
2331          * are theoretically arbitrary.
2332          *
2333          * $sql is expected to be a SELECT, if that makes a difference.
2334          *
2335          * The version provided by default works in MySQL and SQLite. It will very
2336          * likely need to be overridden for most other DBMSes.
2337          *
2338          * @param string $sql SQL query we will append the limit too
2339          * @param int $limit The SQL limit
2340          * @param int|bool $offset The SQL offset (default false)
2341          * @throws DBUnexpectedError
2342          * @return string
2343          */
2344         public function limitResult( $sql, $limit, $offset = false ) {
2345                 if ( !is_numeric( $limit ) ) {
2346                         throw new DBUnexpectedError( $this,
2347                                 "Invalid non-numeric limit passed to limitResult()\n" );
2348                 }
2349
2350                 return "$sql LIMIT "
2351                 . ( ( is_numeric( $offset ) && $offset != 0 ) ? "{$offset}," : "" )
2352                 . "{$limit} ";
2353         }
2354
2355         public function unionSupportsOrderAndLimit() {
2356                 return true; // True for almost every DB supported
2357         }
2358
2359         public function unionQueries( $sqls, $all ) {
2360                 $glue = $all ? ') UNION ALL (' : ') UNION (';
2361
2362                 return '(' . implode( $glue, $sqls ) . ')';
2363         }
2364
2365         public function conditional( $cond, $trueVal, $falseVal ) {
2366                 if ( is_array( $cond ) ) {
2367                         $cond = $this->makeList( $cond, self::LIST_AND );
2368                 }
2369
2370                 return " (CASE WHEN $cond THEN $trueVal ELSE $falseVal END) ";
2371         }
2372
2373         public function strreplace( $orig, $old, $new ) {
2374                 return "REPLACE({$orig}, {$old}, {$new})";
2375         }
2376
2377         public function getServerUptime() {
2378                 return 0;
2379         }
2380
2381         public function wasDeadlock() {
2382                 return false;
2383         }
2384
2385         public function wasLockTimeout() {
2386                 return false;
2387         }
2388
2389         public function wasErrorReissuable() {
2390                 return false;
2391         }
2392
2393         public function wasReadOnlyError() {
2394                 return false;
2395         }
2396
2397         /**
2398          * Do not use this method outside of Database/DBError classes
2399          *
2400          * @param integer|string $errno
2401          * @return bool Whether the given query error was a connection drop
2402          */
2403         public function wasConnectionError( $errno ) {
2404                 return false;
2405         }
2406
2407         public function deadlockLoop() {
2408                 $args = func_get_args();
2409                 $function = array_shift( $args );
2410                 $tries = self::DEADLOCK_TRIES;
2411
2412                 $this->begin( __METHOD__ );
2413
2414                 $retVal = null;
2415                 /** @var Exception $e */
2416                 $e = null;
2417                 do {
2418                         try {
2419                                 $retVal = call_user_func_array( $function, $args );
2420                                 break;
2421                         } catch ( DBQueryError $e ) {
2422                                 if ( $this->wasDeadlock() ) {
2423                                         // Retry after a randomized delay
2424                                         usleep( mt_rand( self::DEADLOCK_DELAY_MIN, self::DEADLOCK_DELAY_MAX ) );
2425                                 } else {
2426                                         // Throw the error back up
2427                                         throw $e;
2428                                 }
2429                         }
2430                 } while ( --$tries > 0 );
2431
2432                 if ( $tries <= 0 ) {
2433                         // Too many deadlocks; give up
2434                         $this->rollback( __METHOD__ );
2435                         throw $e;
2436                 } else {
2437                         $this->commit( __METHOD__ );
2438
2439                         return $retVal;
2440                 }
2441         }
2442
2443         public function masterPosWait( DBMasterPos $pos, $timeout ) {
2444                 # Real waits are implemented in the subclass.
2445                 return 0;
2446         }
2447
2448         public function getReplicaPos() {
2449                 # Stub
2450                 return false;
2451         }
2452
2453         public function getMasterPos() {
2454                 # Stub
2455                 return false;
2456         }
2457
2458         public function serverIsReadOnly() {
2459                 return false;
2460         }
2461
2462         final public function onTransactionResolution( callable $callback, $fname = __METHOD__ ) {
2463                 if ( !$this->mTrxLevel ) {
2464                         throw new DBUnexpectedError( $this, "No transaction is active." );
2465                 }
2466                 $this->mTrxEndCallbacks[] = [ $callback, $fname ];
2467         }
2468
2469         final public function onTransactionIdle( callable $callback, $fname = __METHOD__ ) {
2470                 $this->mTrxIdleCallbacks[] = [ $callback, $fname ];
2471                 if ( !$this->mTrxLevel ) {
2472                         $this->runOnTransactionIdleCallbacks( self::TRIGGER_IDLE );
2473                 }
2474         }
2475
2476         final public function onTransactionPreCommitOrIdle( callable $callback, $fname = __METHOD__ ) {
2477                 if ( $this->mTrxLevel ) {
2478                         $this->mTrxPreCommitCallbacks[] = [ $callback, $fname ];
2479                 } else {
2480                         // If no transaction is active, then make one for this callback
2481                         $this->startAtomic( __METHOD__ );
2482                         try {
2483                                 call_user_func( $callback );
2484                                 $this->endAtomic( __METHOD__ );
2485                         } catch ( Exception $e ) {
2486                                 $this->rollback( __METHOD__, self::FLUSHING_INTERNAL );
2487                                 throw $e;
2488                         }
2489                 }
2490         }
2491
2492         final public function setTransactionListener( $name, callable $callback = null ) {
2493                 if ( $callback ) {
2494                         $this->mTrxRecurringCallbacks[$name] = $callback;
2495                 } else {
2496                         unset( $this->mTrxRecurringCallbacks[$name] );
2497                 }
2498         }
2499
2500         /**
2501          * Whether to disable running of post-COMMIT/ROLLBACK callbacks
2502          *
2503          * This method should not be used outside of Database/LoadBalancer
2504          *
2505          * @param bool $suppress
2506          * @since 1.28
2507          */
2508         final public function setTrxEndCallbackSuppression( $suppress ) {
2509                 $this->mTrxEndCallbacksSuppressed = $suppress;
2510         }
2511
2512         /**
2513          * Actually run and consume any "on transaction idle/resolution" callbacks.
2514          *
2515          * This method should not be used outside of Database/LoadBalancer
2516          *
2517          * @param integer $trigger IDatabase::TRIGGER_* constant
2518          * @since 1.20
2519          * @throws Exception
2520          */
2521         public function runOnTransactionIdleCallbacks( $trigger ) {
2522                 if ( $this->mTrxEndCallbacksSuppressed ) {
2523                         return;
2524                 }
2525
2526                 $autoTrx = $this->getFlag( self::DBO_TRX ); // automatic begin() enabled?
2527                 /** @var Exception $e */
2528                 $e = null; // first exception
2529                 do { // callbacks may add callbacks :)
2530                         $callbacks = array_merge(
2531                                 $this->mTrxIdleCallbacks,
2532                                 $this->mTrxEndCallbacks // include "transaction resolution" callbacks
2533                         );
2534                         $this->mTrxIdleCallbacks = []; // consumed (and recursion guard)
2535                         $this->mTrxEndCallbacks = []; // consumed (recursion guard)
2536                         foreach ( $callbacks as $callback ) {
2537                                 try {
2538                                         list( $phpCallback ) = $callback;
2539                                         $this->clearFlag( self::DBO_TRX ); // make each query its own transaction
2540                                         call_user_func_array( $phpCallback, [ $trigger ] );
2541                                         if ( $autoTrx ) {
2542                                                 $this->setFlag( self::DBO_TRX ); // restore automatic begin()
2543                                         } else {
2544                                                 $this->clearFlag( self::DBO_TRX ); // restore auto-commit
2545                                         }
2546                                 } catch ( Exception $ex ) {
2547                                         call_user_func( $this->errorLogger, $ex );
2548                                         $e = $e ?: $ex;
2549                                         // Some callbacks may use startAtomic/endAtomic, so make sure
2550                                         // their transactions are ended so other callbacks don't fail
2551                                         if ( $this->trxLevel() ) {
2552                                                 $this->rollback( __METHOD__, self::FLUSHING_INTERNAL );
2553                                         }
2554                                 }
2555                         }
2556                 } while ( count( $this->mTrxIdleCallbacks ) );
2557
2558                 if ( $e instanceof Exception ) {
2559                         throw $e; // re-throw any first exception
2560                 }
2561         }
2562
2563         /**
2564          * Actually run and consume any "on transaction pre-commit" callbacks.
2565          *
2566          * This method should not be used outside of Database/LoadBalancer
2567          *
2568          * @since 1.22
2569          * @throws Exception
2570          */
2571         public function runOnTransactionPreCommitCallbacks() {
2572                 $e = null; // first exception
2573                 do { // callbacks may add callbacks :)
2574                         $callbacks = $this->mTrxPreCommitCallbacks;
2575                         $this->mTrxPreCommitCallbacks = []; // consumed (and recursion guard)
2576                         foreach ( $callbacks as $callback ) {
2577                                 try {
2578                                         list( $phpCallback ) = $callback;
2579                                         call_user_func( $phpCallback );
2580                                 } catch ( Exception $ex ) {
2581                                         call_user_func( $this->errorLogger, $ex );
2582                                         $e = $e ?: $ex;
2583                                 }
2584                         }
2585                 } while ( count( $this->mTrxPreCommitCallbacks ) );
2586
2587                 if ( $e instanceof Exception ) {
2588                         throw $e; // re-throw any first exception
2589                 }
2590         }
2591
2592         /**
2593          * Actually run any "transaction listener" callbacks.
2594          *
2595          * This method should not be used outside of Database/LoadBalancer
2596          *
2597          * @param integer $trigger IDatabase::TRIGGER_* constant
2598          * @throws Exception
2599          * @since 1.20
2600          */
2601         public function runTransactionListenerCallbacks( $trigger ) {
2602                 if ( $this->mTrxEndCallbacksSuppressed ) {
2603                         return;
2604                 }
2605
2606                 /** @var Exception $e */
2607                 $e = null; // first exception
2608
2609                 foreach ( $this->mTrxRecurringCallbacks as $phpCallback ) {
2610                         try {
2611                                 $phpCallback( $trigger, $this );
2612                         } catch ( Exception $ex ) {
2613                                 call_user_func( $this->errorLogger, $ex );
2614                                 $e = $e ?: $ex;
2615                         }
2616                 }
2617
2618                 if ( $e instanceof Exception ) {
2619                         throw $e; // re-throw any first exception
2620                 }
2621         }
2622
2623         final public function startAtomic( $fname = __METHOD__ ) {
2624                 if ( !$this->mTrxLevel ) {
2625                         $this->begin( $fname, self::TRANSACTION_INTERNAL );
2626                         // If DBO_TRX is set, a series of startAtomic/endAtomic pairs will result
2627                         // in all changes being in one transaction to keep requests transactional.
2628                         if ( !$this->getFlag( self::DBO_TRX ) ) {
2629                                 $this->mTrxAutomaticAtomic = true;
2630                         }
2631                 }
2632
2633                 $this->mTrxAtomicLevels[] = $fname;
2634         }
2635
2636         final public function endAtomic( $fname = __METHOD__ ) {
2637                 if ( !$this->mTrxLevel ) {
2638                         throw new DBUnexpectedError( $this, "No atomic transaction is open (got $fname)." );
2639                 }
2640                 if ( !$this->mTrxAtomicLevels ||
2641                         array_pop( $this->mTrxAtomicLevels ) !== $fname
2642                 ) {
2643                         throw new DBUnexpectedError( $this, "Invalid atomic section ended (got $fname)." );
2644                 }
2645
2646                 if ( !$this->mTrxAtomicLevels && $this->mTrxAutomaticAtomic ) {
2647                         $this->commit( $fname, self::FLUSHING_INTERNAL );
2648                 }
2649         }
2650
2651         final public function doAtomicSection( $fname, callable $callback ) {
2652                 $this->startAtomic( $fname );
2653                 try {
2654                         $res = call_user_func_array( $callback, [ $this, $fname ] );
2655                 } catch ( Exception $e ) {
2656                         $this->rollback( $fname, self::FLUSHING_INTERNAL );
2657                         throw $e;
2658                 }
2659                 $this->endAtomic( $fname );
2660
2661                 return $res;
2662         }
2663
2664         final public function begin( $fname = __METHOD__, $mode = self::TRANSACTION_EXPLICIT ) {
2665                 // Protect against mismatched atomic section, transaction nesting, and snapshot loss
2666                 if ( $this->mTrxLevel ) {
2667                         if ( $this->mTrxAtomicLevels ) {
2668                                 $levels = implode( ', ', $this->mTrxAtomicLevels );
2669                                 $msg = "$fname: Got explicit BEGIN while atomic section(s) $levels are open.";
2670                                 throw new DBUnexpectedError( $this, $msg );
2671                         } elseif ( !$this->mTrxAutomatic ) {
2672                                 $msg = "$fname: Explicit transaction already active (from {$this->mTrxFname}).";
2673                                 throw new DBUnexpectedError( $this, $msg );
2674                         } else {
2675                                 // @TODO: make this an exception at some point
2676                                 $msg = "$fname: Implicit transaction already active (from {$this->mTrxFname}).";
2677                                 $this->queryLogger->error( $msg );
2678                                 return; // join the main transaction set
2679                         }
2680                 } elseif ( $this->getFlag( self::DBO_TRX ) && $mode !== self::TRANSACTION_INTERNAL ) {
2681                         // @TODO: make this an exception at some point
2682                         $msg = "$fname: Implicit transaction expected (DBO_TRX set).";
2683                         $this->queryLogger->error( $msg );
2684                         return; // let any writes be in the main transaction
2685                 }
2686
2687                 // Avoid fatals if close() was called
2688                 $this->assertOpen();
2689
2690                 $this->doBegin( $fname );
2691                 $this->mTrxTimestamp = microtime( true );
2692                 $this->mTrxFname = $fname;
2693                 $this->mTrxDoneWrites = false;
2694                 $this->mTrxAutomaticAtomic = false;
2695                 $this->mTrxAtomicLevels = [];
2696                 $this->mTrxShortId = sprintf( '%06x', mt_rand( 0, 0xffffff ) );
2697                 $this->mTrxWriteDuration = 0.0;
2698                 $this->mTrxWriteQueryCount = 0;
2699                 $this->mTrxWriteAdjDuration = 0.0;
2700                 $this->mTrxWriteAdjQueryCount = 0;
2701                 $this->mTrxWriteCallers = [];
2702                 // First SELECT after BEGIN will establish the snapshot in REPEATABLE-READ.
2703                 // Get an estimate of the replica DB lag before then, treating estimate staleness
2704                 // as lag itself just to be safe
2705                 $status = $this->getApproximateLagStatus();
2706                 $this->mTrxReplicaLag = $status['lag'] + ( microtime( true ) - $status['since'] );
2707                 // T147697: make explicitTrxActive() return true until begin() finishes. This way, no
2708                 // caller will think its OK to muck around with the transaction just because startAtomic()
2709                 // has not yet completed (e.g. setting mTrxAtomicLevels).
2710                 $this->mTrxAutomatic = ( $mode === self::TRANSACTION_INTERNAL );
2711         }
2712
2713         /**
2714          * Issues the BEGIN command to the database server.
2715          *
2716          * @see Database::begin()
2717          * @param string $fname
2718          */
2719         protected function doBegin( $fname ) {
2720                 $this->query( 'BEGIN', $fname );
2721                 $this->mTrxLevel = 1;
2722         }
2723
2724         final public function commit( $fname = __METHOD__, $flush = '' ) {
2725                 if ( $this->mTrxLevel && $this->mTrxAtomicLevels ) {
2726                         // There are still atomic sections open. This cannot be ignored
2727                         $levels = implode( ', ', $this->mTrxAtomicLevels );
2728                         throw new DBUnexpectedError(
2729                                 $this,
2730                                 "$fname: Got COMMIT while atomic sections $levels are still open."
2731                         );
2732                 }
2733
2734                 if ( $flush === self::FLUSHING_INTERNAL || $flush === self::FLUSHING_ALL_PEERS ) {
2735                         if ( !$this->mTrxLevel ) {
2736                                 return; // nothing to do
2737                         } elseif ( !$this->mTrxAutomatic ) {
2738                                 throw new DBUnexpectedError(
2739                                         $this,
2740                                         "$fname: Flushing an explicit transaction, getting out of sync."
2741                                 );
2742                         }
2743                 } else {
2744                         if ( !$this->mTrxLevel ) {
2745                                 $this->queryLogger->error(
2746                                         "$fname: No transaction to commit, something got out of sync." );
2747                                 return; // nothing to do
2748                         } elseif ( $this->mTrxAutomatic ) {
2749                                 // @TODO: make this an exception at some point
2750                                 $msg = "$fname: Explicit commit of implicit transaction.";
2751                                 $this->queryLogger->error( $msg );
2752                                 return; // wait for the main transaction set commit round
2753                         }
2754                 }
2755
2756                 // Avoid fatals if close() was called
2757                 $this->assertOpen();
2758
2759                 $this->runOnTransactionPreCommitCallbacks();
2760                 $writeTime = $this->pendingWriteQueryDuration( self::ESTIMATE_DB_APPLY );
2761                 $this->doCommit( $fname );
2762                 if ( $this->mTrxDoneWrites ) {
2763                         $this->mLastWriteTime = microtime( true );
2764                         $this->trxProfiler->transactionWritingOut(
2765                                 $this->mServer, $this->mDBname, $this->mTrxShortId, $writeTime );
2766                 }
2767
2768                 $this->runOnTransactionIdleCallbacks( self::TRIGGER_COMMIT );
2769                 $this->runTransactionListenerCallbacks( self::TRIGGER_COMMIT );
2770         }
2771
2772         /**
2773          * Issues the COMMIT command to the database server.
2774          *
2775          * @see Database::commit()
2776          * @param string $fname
2777          */
2778         protected function doCommit( $fname ) {
2779                 if ( $this->mTrxLevel ) {
2780                         $this->query( 'COMMIT', $fname );
2781                         $this->mTrxLevel = 0;
2782                 }
2783         }
2784
2785         final public function rollback( $fname = __METHOD__, $flush = '' ) {
2786                 if ( $flush === self::FLUSHING_INTERNAL || $flush === self::FLUSHING_ALL_PEERS ) {
2787                         if ( !$this->mTrxLevel ) {
2788                                 return; // nothing to do
2789                         }
2790                 } else {
2791                         if ( !$this->mTrxLevel ) {
2792                                 $this->queryLogger->error(
2793                                         "$fname: No transaction to rollback, something got out of sync." );
2794                                 return; // nothing to do
2795                         } elseif ( $this->getFlag( self::DBO_TRX ) ) {
2796                                 throw new DBUnexpectedError(
2797                                         $this,
2798                                         "$fname: Expected mass rollback of all peer databases (DBO_TRX set)."
2799                                 );
2800                         }
2801                 }
2802
2803                 // Avoid fatals if close() was called
2804                 $this->assertOpen();
2805
2806                 $this->doRollback( $fname );
2807                 $this->mTrxAtomicLevels = [];
2808                 if ( $this->mTrxDoneWrites ) {
2809                         $this->trxProfiler->transactionWritingOut(
2810                                 $this->mServer, $this->mDBname, $this->mTrxShortId );
2811                 }
2812
2813                 $this->mTrxIdleCallbacks = []; // clear
2814                 $this->mTrxPreCommitCallbacks = []; // clear
2815                 $this->runOnTransactionIdleCallbacks( self::TRIGGER_ROLLBACK );
2816                 $this->runTransactionListenerCallbacks( self::TRIGGER_ROLLBACK );
2817         }
2818
2819         /**
2820          * Issues the ROLLBACK command to the database server.
2821          *
2822          * @see Database::rollback()
2823          * @param string $fname
2824          */
2825         protected function doRollback( $fname ) {
2826                 if ( $this->mTrxLevel ) {
2827                         # Disconnects cause rollback anyway, so ignore those errors
2828                         $ignoreErrors = true;
2829                         $this->query( 'ROLLBACK', $fname, $ignoreErrors );
2830                         $this->mTrxLevel = 0;
2831                 }
2832         }
2833
2834         public function flushSnapshot( $fname = __METHOD__ ) {
2835                 if ( $this->writesOrCallbacksPending() || $this->explicitTrxActive() ) {
2836                         // This only flushes transactions to clear snapshots, not to write data
2837                         $fnames = implode( ', ', $this->pendingWriteAndCallbackCallers() );
2838                         throw new DBUnexpectedError(
2839                                 $this,
2840                                 "$fname: Cannot flush snapshot because writes are pending ($fnames)."
2841                         );
2842                 }
2843
2844                 $this->commit( $fname, self::FLUSHING_INTERNAL );
2845         }
2846
2847         public function explicitTrxActive() {
2848                 return $this->mTrxLevel && ( $this->mTrxAtomicLevels || !$this->mTrxAutomatic );
2849         }
2850
2851         /**
2852          * Creates a new table with structure copied from existing table
2853          * Note that unlike most database abstraction functions, this function does not
2854          * automatically append database prefix, because it works at a lower
2855          * abstraction level.
2856          * The table names passed to this function shall not be quoted (this
2857          * function calls addIdentifierQuotes when needed).
2858          *
2859          * @param string $oldName Name of table whose structure should be copied
2860          * @param string $newName Name of table to be created
2861          * @param bool $temporary Whether the new table should be temporary
2862          * @param string $fname Calling function name
2863          * @throws RuntimeException
2864          * @return bool True if operation was successful
2865          */
2866         public function duplicateTableStructure( $oldName, $newName, $temporary = false,
2867                 $fname = __METHOD__
2868         ) {
2869                 throw new RuntimeException( __METHOD__ . ' is not implemented in descendant class' );
2870         }
2871
2872         public function listTables( $prefix = null, $fname = __METHOD__ ) {
2873                 throw new RuntimeException( __METHOD__ . ' is not implemented in descendant class' );
2874         }
2875
2876         public function listViews( $prefix = null, $fname = __METHOD__ ) {
2877                 throw new RuntimeException( __METHOD__ . ' is not implemented in descendant class' );
2878         }
2879
2880         public function timestamp( $ts = 0 ) {
2881                 $t = new ConvertibleTimestamp( $ts );
2882                 // Let errors bubble up to avoid putting garbage in the DB
2883                 return $t->getTimestamp( TS_MW );
2884         }
2885
2886         public function timestampOrNull( $ts = null ) {
2887                 if ( is_null( $ts ) ) {
2888                         return null;
2889                 } else {
2890                         return $this->timestamp( $ts );
2891                 }
2892         }
2893
2894         /**
2895          * Take the result from a query, and wrap it in a ResultWrapper if
2896          * necessary. Boolean values are passed through as is, to indicate success
2897          * of write queries or failure.
2898          *
2899          * Once upon a time, Database::query() returned a bare MySQL result
2900          * resource, and it was necessary to call this function to convert it to
2901          * a wrapper. Nowadays, raw database objects are never exposed to external
2902          * callers, so this is unnecessary in external code.
2903          *
2904          * @param bool|ResultWrapper|resource|object $result
2905          * @return bool|ResultWrapper
2906          */
2907         protected function resultObject( $result ) {
2908                 if ( !$result ) {
2909                         return false;
2910                 } elseif ( $result instanceof ResultWrapper ) {
2911                         return $result;
2912                 } elseif ( $result === true ) {
2913                         // Successful write query
2914                         return $result;
2915                 } else {
2916                         return new ResultWrapper( $this, $result );
2917                 }
2918         }
2919
2920         public function ping( &$rtt = null ) {
2921                 // Avoid hitting the server if it was hit recently
2922                 if ( $this->isOpen() && ( microtime( true ) - $this->lastPing ) < self::PING_TTL ) {
2923                         if ( !func_num_args() || $this->mRTTEstimate > 0 ) {
2924                                 $rtt = $this->mRTTEstimate;
2925                                 return true; // don't care about $rtt
2926                         }
2927                 }
2928
2929                 // This will reconnect if possible or return false if not
2930                 $this->clearFlag( self::DBO_TRX, self::REMEMBER_PRIOR );
2931                 $ok = ( $this->query( self::PING_QUERY, __METHOD__, true ) !== false );
2932                 $this->restoreFlags( self::RESTORE_PRIOR );
2933
2934                 if ( $ok ) {
2935                         $rtt = $this->mRTTEstimate;
2936                 }
2937
2938                 return $ok;
2939         }
2940
2941         /**
2942          * @return bool
2943          */
2944         protected function reconnect() {
2945                 $this->closeConnection();
2946                 $this->mOpened = false;
2947                 $this->mConn = false;
2948                 try {
2949                         $this->open( $this->mServer, $this->mUser, $this->mPassword, $this->mDBname );
2950                         $this->lastPing = microtime( true );
2951                         $ok = true;
2952                 } catch ( DBConnectionError $e ) {
2953                         $ok = false;
2954                 }
2955
2956                 return $ok;
2957         }
2958
2959         public function getSessionLagStatus() {
2960                 return $this->getTransactionLagStatus() ?: $this->getApproximateLagStatus();
2961         }
2962
2963         /**
2964          * Get the replica DB lag when the current transaction started
2965          *
2966          * This is useful when transactions might use snapshot isolation
2967          * (e.g. REPEATABLE-READ in innodb), so the "real" lag of that data
2968          * is this lag plus transaction duration. If they don't, it is still
2969          * safe to be pessimistic. This returns null if there is no transaction.
2970          *
2971          * @return array|null ('lag': seconds or false on error, 'since': UNIX timestamp of BEGIN)
2972          * @since 1.27
2973          */
2974         protected function getTransactionLagStatus() {
2975                 return $this->mTrxLevel
2976                         ? [ 'lag' => $this->mTrxReplicaLag, 'since' => $this->trxTimestamp() ]
2977                         : null;
2978         }
2979
2980         /**
2981          * Get a replica DB lag estimate for this server
2982          *
2983          * @return array ('lag': seconds or false on error, 'since': UNIX timestamp of estimate)
2984          * @since 1.27
2985          */
2986         protected function getApproximateLagStatus() {
2987                 return [
2988                         'lag'   => $this->getLBInfo( 'replica' ) ? $this->getLag() : 0,
2989                         'since' => microtime( true )
2990                 ];
2991         }
2992
2993         /**
2994          * Merge the result of getSessionLagStatus() for several DBs
2995          * using the most pessimistic values to estimate the lag of
2996          * any data derived from them in combination
2997          *
2998          * This is information is useful for caching modules
2999          *
3000          * @see WANObjectCache::set()
3001          * @see WANObjectCache::getWithSetCallback()
3002          *
3003          * @param IDatabase $db1
3004          * @param IDatabase ...
3005          * @return array Map of values:
3006          *   - lag: highest lag of any of the DBs or false on error (e.g. replication stopped)
3007          *   - since: oldest UNIX timestamp of any of the DB lag estimates
3008          *   - pending: whether any of the DBs have uncommitted changes
3009          * @since 1.27
3010          */
3011         public static function getCacheSetOptions( IDatabase $db1 ) {
3012                 $res = [ 'lag' => 0, 'since' => INF, 'pending' => false ];
3013                 foreach ( func_get_args() as $db ) {
3014                         /** @var IDatabase $db */
3015                         $status = $db->getSessionLagStatus();
3016                         if ( $status['lag'] === false ) {
3017                                 $res['lag'] = false;
3018                         } elseif ( $res['lag'] !== false ) {
3019                                 $res['lag'] = max( $res['lag'], $status['lag'] );
3020                         }
3021                         $res['since'] = min( $res['since'], $status['since'] );
3022                         $res['pending'] = $res['pending'] ?: $db->writesPending();
3023                 }
3024
3025                 return $res;
3026         }
3027
3028         public function getLag() {
3029                 return 0;
3030         }
3031
3032         public function maxListLen() {
3033                 return 0;
3034         }
3035
3036         public function encodeBlob( $b ) {
3037                 return $b;
3038         }
3039
3040         public function decodeBlob( $b ) {
3041                 if ( $b instanceof Blob ) {
3042                         $b = $b->fetch();
3043                 }
3044                 return $b;
3045         }
3046
3047         public function setSessionOptions( array $options ) {
3048         }
3049
3050         public function sourceFile(
3051                 $filename,
3052                 callable $lineCallback = null,
3053                 callable $resultCallback = null,
3054                 $fname = false,
3055                 callable $inputCallback = null
3056         ) {
3057                 MediaWiki\suppressWarnings();
3058                 $fp = fopen( $filename, 'r' );
3059                 MediaWiki\restoreWarnings();
3060
3061                 if ( false === $fp ) {
3062                         throw new RuntimeException( "Could not open \"{$filename}\".\n" );
3063                 }
3064
3065                 if ( !$fname ) {
3066                         $fname = __METHOD__ . "( $filename )";
3067                 }
3068
3069                 try {
3070                         $error = $this->sourceStream(
3071                                 $fp, $lineCallback, $resultCallback, $fname, $inputCallback );
3072                 } catch ( Exception $e ) {
3073                         fclose( $fp );
3074                         throw $e;
3075                 }
3076
3077                 fclose( $fp );
3078
3079                 return $error;
3080         }
3081
3082         public function setSchemaVars( $vars ) {
3083                 $this->mSchemaVars = $vars;
3084         }
3085
3086         public function sourceStream(
3087                 $fp,
3088                 callable $lineCallback = null,
3089                 callable $resultCallback = null,
3090                 $fname = __METHOD__,
3091                 callable $inputCallback = null
3092         ) {
3093                 $cmd = '';
3094
3095                 while ( !feof( $fp ) ) {
3096                         if ( $lineCallback ) {
3097                                 call_user_func( $lineCallback );
3098                         }
3099
3100                         $line = trim( fgets( $fp ) );
3101
3102                         if ( $line == '' ) {
3103                                 continue;
3104                         }
3105
3106                         if ( '-' == $line[0] && '-' == $line[1] ) {
3107                                 continue;
3108                         }
3109
3110                         if ( $cmd != '' ) {
3111                                 $cmd .= ' ';
3112                         }
3113
3114                         $done = $this->streamStatementEnd( $cmd, $line );
3115
3116                         $cmd .= "$line\n";
3117
3118                         if ( $done || feof( $fp ) ) {
3119                                 $cmd = $this->replaceVars( $cmd );
3120
3121                                 if ( !$inputCallback || call_user_func( $inputCallback, $cmd ) ) {
3122                                         $res = $this->query( $cmd, $fname );
3123
3124                                         if ( $resultCallback ) {
3125                                                 call_user_func( $resultCallback, $res, $this );
3126                                         }
3127
3128                                         if ( false === $res ) {
3129                                                 $err = $this->lastError();
3130
3131                                                 return "Query \"{$cmd}\" failed with error code \"$err\".\n";
3132                                         }
3133                                 }
3134                                 $cmd = '';
3135                         }
3136                 }
3137
3138                 return true;
3139         }
3140
3141         /**
3142          * Called by sourceStream() to check if we've reached a statement end
3143          *
3144          * @param string &$sql SQL assembled so far
3145          * @param string &$newLine New line about to be added to $sql
3146          * @return bool Whether $newLine contains end of the statement
3147          */
3148         public function streamStatementEnd( &$sql, &$newLine ) {
3149                 if ( $this->delimiter ) {
3150                         $prev = $newLine;
3151                         $newLine = preg_replace(
3152                                 '/' . preg_quote( $this->delimiter, '/' ) . '$/', '', $newLine );
3153                         if ( $newLine != $prev ) {
3154                                 return true;
3155                         }
3156                 }
3157
3158                 return false;
3159         }
3160
3161         /**
3162          * Database independent variable replacement. Replaces a set of variables
3163          * in an SQL statement with their contents as given by $this->getSchemaVars().
3164          *
3165          * Supports '{$var}' `{$var}` and / *$var* / (without the spaces) style variables.
3166          *
3167          * - '{$var}' should be used for text and is passed through the database's
3168          *   addQuotes method.
3169          * - `{$var}` should be used for identifiers (e.g. table and database names).
3170          *   It is passed through the database's addIdentifierQuotes method which
3171          *   can be overridden if the database uses something other than backticks.
3172          * - / *_* / or / *$wgDBprefix* / passes the name that follows through the
3173          *   database's tableName method.
3174          * - / *i* / passes the name that follows through the database's indexName method.
3175          * - In all other cases, / *$var* / is left unencoded. Except for table options,
3176          *   its use should be avoided. In 1.24 and older, string encoding was applied.
3177          *
3178          * @param string $ins SQL statement to replace variables in
3179          * @return string The new SQL statement with variables replaced
3180          */
3181         protected function replaceVars( $ins ) {
3182                 $vars = $this->getSchemaVars();
3183                 return preg_replace_callback(
3184                         '!
3185                                 /\* (\$wgDBprefix|[_i]) \*/ (\w*) | # 1-2. tableName, indexName
3186                                 \'\{\$ (\w+) }\'                  | # 3. addQuotes
3187                                 `\{\$ (\w+) }`                    | # 4. addIdentifierQuotes
3188                                 /\*\$ (\w+) \*/                     # 5. leave unencoded
3189                         !x',
3190                         function ( $m ) use ( $vars ) {
3191                                 // Note: Because of <https://bugs.php.net/bug.php?id=51881>,
3192                                 // check for both nonexistent keys *and* the empty string.
3193                                 if ( isset( $m[1] ) && $m[1] !== '' ) {
3194                                         if ( $m[1] === 'i' ) {
3195                                                 return $this->indexName( $m[2] );
3196                                         } else {
3197                                                 return $this->tableName( $m[2] );
3198                                         }
3199                                 } elseif ( isset( $m[3] ) && $m[3] !== '' && array_key_exists( $m[3], $vars ) ) {
3200                                         return $this->addQuotes( $vars[$m[3]] );
3201                                 } elseif ( isset( $m[4] ) && $m[4] !== '' && array_key_exists( $m[4], $vars ) ) {
3202                                         return $this->addIdentifierQuotes( $vars[$m[4]] );
3203                                 } elseif ( isset( $m[5] ) && $m[5] !== '' && array_key_exists( $m[5], $vars ) ) {
3204                                         return $vars[$m[5]];
3205                                 } else {
3206                                         return $m[0];
3207                                 }
3208                         },
3209                         $ins
3210                 );
3211         }
3212
3213         /**
3214          * Get schema variables. If none have been set via setSchemaVars(), then
3215          * use some defaults from the current object.
3216          *
3217          * @return array
3218          */
3219         protected function getSchemaVars() {
3220                 if ( $this->mSchemaVars ) {
3221                         return $this->mSchemaVars;
3222                 } else {
3223                         return $this->getDefaultSchemaVars();
3224                 }
3225         }
3226
3227         /**
3228          * Get schema variables to use if none have been set via setSchemaVars().
3229          *
3230          * Override this in derived classes to provide variables for tables.sql
3231          * and SQL patch files.
3232          *
3233          * @return array
3234          */
3235         protected function getDefaultSchemaVars() {
3236                 return [];
3237         }
3238
3239         public function lockIsFree( $lockName, $method ) {
3240                 return true;
3241         }
3242
3243         public function lock( $lockName, $method, $timeout = 5 ) {
3244                 $this->mNamedLocksHeld[$lockName] = 1;
3245
3246                 return true;
3247         }
3248
3249         public function unlock( $lockName, $method ) {
3250                 unset( $this->mNamedLocksHeld[$lockName] );
3251
3252                 return true;
3253         }
3254
3255         public function getScopedLockAndFlush( $lockKey, $fname, $timeout ) {
3256                 if ( $this->writesOrCallbacksPending() ) {
3257                         // This only flushes transactions to clear snapshots, not to write data
3258                         $fnames = implode( ', ', $this->pendingWriteAndCallbackCallers() );
3259                         throw new DBUnexpectedError(
3260                                 $this,
3261                                 "$fname: Cannot flush pre-lock snapshot because writes are pending ($fnames)."
3262                         );
3263                 }
3264
3265                 if ( !$this->lock( $lockKey, $fname, $timeout ) ) {
3266                         return null;
3267                 }
3268
3269                 $unlocker = new ScopedCallback( function () use ( $lockKey, $fname ) {
3270                         if ( $this->trxLevel() ) {
3271                                 // There is a good chance an exception was thrown, causing any early return
3272                                 // from the caller. Let any error handler get a chance to issue rollback().
3273                                 // If there isn't one, let the error bubble up and trigger server-side rollback.
3274                                 $this->onTransactionResolution(
3275                                         function () use ( $lockKey, $fname ) {
3276                                                 $this->unlock( $lockKey, $fname );
3277                                         },
3278                                         $fname
3279                                 );
3280                         } else {
3281                                 $this->unlock( $lockKey, $fname );
3282                         }
3283                 } );
3284
3285                 $this->commit( $fname, self::FLUSHING_INTERNAL );
3286
3287                 return $unlocker;
3288         }
3289
3290         public function namedLocksEnqueue() {
3291                 return false;
3292         }
3293
3294         /**
3295          * Lock specific tables
3296          *
3297          * @param array $read Array of tables to lock for read access
3298          * @param array $write Array of tables to lock for write access
3299          * @param string $method Name of caller
3300          * @param bool $lowPriority Whether to indicate writes to be LOW PRIORITY
3301          * @return bool
3302          */
3303         public function lockTables( $read, $write, $method, $lowPriority = true ) {
3304                 return true;
3305         }
3306
3307         /**
3308          * Unlock specific tables
3309          *
3310          * @param string $method The caller
3311          * @return bool
3312          */
3313         public function unlockTables( $method ) {
3314                 return true;
3315         }
3316
3317         /**
3318          * Delete a table
3319          * @param string $tableName
3320          * @param string $fName
3321          * @return bool|ResultWrapper
3322          * @since 1.18
3323          */
3324         public function dropTable( $tableName, $fName = __METHOD__ ) {
3325                 if ( !$this->tableExists( $tableName, $fName ) ) {
3326                         return false;
3327                 }
3328                 $sql = "DROP TABLE " . $this->tableName( $tableName ) . " CASCADE";
3329
3330                 return $this->query( $sql, $fName );
3331         }
3332
3333         public function getInfinity() {
3334                 return 'infinity';
3335         }
3336
3337         public function encodeExpiry( $expiry ) {
3338                 return ( $expiry == '' || $expiry == 'infinity' || $expiry == $this->getInfinity() )
3339                         ? $this->getInfinity()
3340                         : $this->timestamp( $expiry );
3341         }
3342
3343         public function decodeExpiry( $expiry, $format = TS_MW ) {
3344                 if ( $expiry == '' || $expiry == 'infinity' || $expiry == $this->getInfinity() ) {
3345                         return 'infinity';
3346                 }
3347
3348                 return ConvertibleTimestamp::convert( $format, $expiry );
3349         }
3350
3351         public function setBigSelects( $value = true ) {
3352                 // no-op
3353         }
3354
3355         public function isReadOnly() {
3356                 return ( $this->getReadOnlyReason() !== false );
3357         }
3358
3359         /**
3360          * @return string|bool Reason this DB is read-only or false if it is not
3361          */
3362         protected function getReadOnlyReason() {
3363                 $reason = $this->getLBInfo( 'readOnlyReason' );
3364
3365                 return is_string( $reason ) ? $reason : false;
3366         }
3367
3368         public function setTableAliases( array $aliases ) {
3369                 $this->tableAliases = $aliases;
3370         }
3371
3372         /**
3373          * @return bool Whether a DB user is required to access the DB
3374          * @since 1.28
3375          */
3376         protected function requiresDatabaseUser() {
3377                 return true;
3378         }
3379
3380         /**
3381          * Get the underlying binding handle, mConn
3382          *
3383          * Makes sure that mConn is set (disconnects and ping() failure can unset it).
3384          * This catches broken callers than catch and ignore disconnection exceptions.
3385          * Unlike checking isOpen(), this is safe to call inside of open().
3386          *
3387          * @return resource|object
3388          * @throws DBUnexpectedError
3389          * @since 1.26
3390          */
3391         protected function getBindingHandle() {
3392                 if ( !$this->mConn ) {
3393                         throw new DBUnexpectedError(
3394                                 $this,
3395                                 'DB connection was already closed or the connection dropped.'
3396                         );
3397                 }
3398
3399                 return $this->mConn;
3400         }
3401
3402         /**
3403          * @since 1.19
3404          * @return string
3405          */
3406         public function __toString() {
3407                 return (string)$this->mConn;
3408         }
3409
3410         /**
3411          * Make sure that copies do not share the same client binding handle
3412          * @throws DBConnectionError
3413          */
3414         public function __clone() {
3415                 $this->connLogger->warning(
3416                         "Cloning " . get_class( $this ) . " is not recomended; forking connection:\n" .
3417                         ( new RuntimeException() )->getTraceAsString()
3418                 );
3419
3420                 if ( $this->isOpen() ) {
3421                         // Open a new connection resource without messing with the old one
3422                         $this->mOpened = false;
3423                         $this->mConn = false;
3424                         $this->mTrxEndCallbacks = []; // don't copy
3425                         $this->handleSessionLoss(); // no trx or locks anymore
3426                         $this->open( $this->mServer, $this->mUser, $this->mPassword, $this->mDBname );
3427                         $this->lastPing = microtime( true );
3428                 }
3429         }
3430
3431         /**
3432          * Called by serialize. Throw an exception when DB connection is serialized.
3433          * This causes problems on some database engines because the connection is
3434          * not restored on unserialize.
3435          */
3436         public function __sleep() {
3437                 throw new RuntimeException( 'Database serialization may cause problems, since ' .
3438                         'the connection is not restored on wakeup.' );
3439         }
3440
3441         /**
3442          * Run a few simple sanity checks and close dangling connections
3443          */
3444         public function __destruct() {
3445                 if ( $this->mTrxLevel && $this->mTrxDoneWrites ) {
3446                         trigger_error( "Uncommitted DB writes (transaction from {$this->mTrxFname})." );
3447                 }
3448
3449                 $danglingWriters = $this->pendingWriteAndCallbackCallers();
3450                 if ( $danglingWriters ) {
3451                         $fnames = implode( ', ', $danglingWriters );
3452                         trigger_error( "DB transaction writes or callbacks still pending ($fnames)." );
3453                 }
3454
3455                 if ( $this->mConn ) {
3456                         // Avoid connection leaks for sanity. Normally, resources close at script completion.
3457                         // The connection might already be closed in zend/hhvm by now, so suppress warnings.
3458                         \MediaWiki\suppressWarnings();
3459                         $this->closeConnection();
3460                         \MediaWiki\restoreWarnings();
3461                         $this->mConn = false;
3462                         $this->mOpened = false;
3463                 }
3464         }
3465 }
3466
3467 class_alias( 'Database', 'DatabaseBase' );