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
 661                 return $this->getLastPHPError();
 662         }
 663
 664         /**
 665          * @return string|bool Last PHP error for this DB (typically connection errors)
 666          */
 667         protected function getLastPHPError() {
 668                 if ( $this->mPHPError ) {
 669                         $error = preg_replace( '!\[<a.*</a>\]!', '', $this->mPHPError );
 670                         $error = preg_replace( '!^.*?:\s?(.*)$!', '$1', $error );
 671
 672                         return $error;
 673                 }
 674
 675                 return false;
 676         }
 677
 678         /**
 679          * This method should not be used outside of Database classes
 680          *
 681          * @param int $errno
 682          * @param string $errstr
 683          */
 684         public function connectionErrorLogger( $errno, $errstr ) {
 685                 $this->mPHPError = $errstr;
 686         }
 687
 688         /**
 689          * Create a log context to pass to PSR-3 logger functions.
 690          *
 691          * @param array $extras Additional data to add to context
 692          * @return array
 693          */
 694         protected function getLogContext( array $extras = [] ) {
 695                 return array_merge(
 696                         [
 697                                 'db_server' => $this->mServer,
 698                                 'db_name' => $this->mDBname,
 699                                 'db_user' => $this->mUser,
 700                         ],
 701                         $extras
 702                 );
 703         }
 704
 705         public function close() {
 706                 if ( $this->mConn ) {
 707                         if ( $this->trxLevel() ) {
 708                                 $this->commit( __METHOD__, self::FLUSHING_INTERNAL );
 709                         }
 710
 711                         $closed = $this->closeConnection();
 712                         $this->mConn = false;
 713                 } elseif ( $this->mTrxIdleCallbacks || $this->mTrxEndCallbacks ) { // sanity
 714                         throw new RuntimeException( "Transaction callbacks still pending." );
 715                 } else {
 716                         $closed = true;
 717                 }
 718                 $this->mOpened = false;
 719
 720                 return $closed;
 721         }
 722
 723         /**
 724          * Make sure isOpen() returns true as a sanity check
 725          *
 726          * @throws DBUnexpectedError
 727          */
 728         protected function assertOpen() {
 729                 if ( !$this->isOpen() ) {
 730                         throw new DBUnexpectedError( $this, "DB connection was already closed." );
 731                 }
 732         }
 733
 734         /**
 735          * Closes underlying database connection
 736          * @since 1.20
 737          * @return bool Whether connection was closed successfully
 738          */
 739         abstract protected function closeConnection();
 740
 741         public function reportConnectionError( $error = 'Unknown error' ) {
 742                 $myError = $this->lastError();
 743                 if ( $myError ) {
 744                         $error = $myError;
 745                 }
 746
 747                 # New method
 748                 throw new DBConnectionError( $this, $error );
 749         }
 750
 751         /**
 752          * The DBMS-dependent part of query()
 753          *
 754          * @param string $sql SQL query.
 755          * @return ResultWrapper|bool Result object to feed to fetchObject,
 756          *   fetchRow, ...; or false on failure
 757          */
 758         abstract protected function doQuery( $sql );
 759
 760         /**
 761          * Determine whether a query writes to the DB.
 762          * Should return true if unsure.
 763          *
 764          * @param string $sql
 765          * @return bool
 766          */
 767         protected function isWriteQuery( $sql ) {
 768                 return !preg_match(
 769                         '/^(?:SELECT|BEGIN|ROLLBACK|COMMIT|SET|SHOW|EXPLAIN|\(SELECT)\b/i', $sql );
 770         }
 771
 772         /**
 773          * @param $sql
 774          * @return string|null
 775          */
 776         protected function getQueryVerb( $sql ) {
 777                 return preg_match( '/^\s*([a-z]+)/i', $sql, $m ) ? strtoupper( $m[1] ) : null;
 778         }
 779
 780         /**
 781          * Determine whether a SQL statement is sensitive to isolation level.
 782          * A SQL statement is considered transactable if its result could vary
 783          * depending on the transaction isolation level. Operational commands
 784          * such as 'SET' and 'SHOW' are not considered to be transactable.
 785          *
 786          * @param string $sql
 787          * @return bool
 788          */
 789         protected function isTransactableQuery( $sql ) {
 790                 return !in_array(
 791                         $this->getQueryVerb( $sql ),
 792                         [ 'BEGIN', 'COMMIT', 'ROLLBACK', 'SHOW', 'SET', 'CREATE', 'ALTER' ],
 793                         true
 794                 );
 795         }
 796
 797         /**
 798          * @param string $sql A SQL query
 799          * @return bool Whether $sql is SQL for creating/dropping a new TEMPORARY table
 800          */
 801         protected function registerTempTableOperation( $sql ) {
 802                 if ( preg_match(
 803                         '/^CREATE\s+TEMPORARY\s+TABLE\s+(?:IF\s+NOT\s+EXISTS\s+)?[`"\']?(\w+)[`"\']?/i',
 804                         $sql,
 805                         $matches
 806                 ) ) {
 807                         $this->mSessionTempTables[$matches[1]] = 1;
 808
 809                         return true;
 810                 } elseif ( preg_match(
 811                         '/^DROP\s+(?:TEMPORARY\s+)?TABLE\s+(?:IF\s+EXISTS\s+)?[`"\']?(\w+)[`"\']?/i',
 812                         $sql,
 813                         $matches
 814                 ) ) {
 815                         unset( $this->mSessionTempTables[$matches[1]] );
 816
 817                         return true;
 818                 } elseif ( preg_match(
 819                         '/^(?:INSERT\s+(?:\w+\s+)?INTO|UPDATE|DELETE\s+FROM)\s+[`"\']?(\w+)[`"\']?/i',
 820                         $sql,
 821                         $matches
 822                 ) ) {
 823                         return isset( $this->mSessionTempTables[$matches[1]] );
 824                 }
 825
 826                 return false;
 827         }
 828
 829         public function query( $sql, $fname = __METHOD__, $tempIgnore = false ) {
 830                 $priorWritesPending = $this->writesOrCallbacksPending();
 831                 $this->mLastQuery = $sql;
 832
 833                 $isWrite = $this->isWriteQuery( $sql ) && !$this->registerTempTableOperation( $sql );
 834                 if ( $isWrite ) {
 835                         $reason = $this->getReadOnlyReason();
 836                         if ( $reason !== false ) {
 837                                 throw new DBReadOnlyError( $this, "Database is read-only: $reason" );
 838                         }
 839                         # Set a flag indicating that writes have been done
 840                         $this->mLastWriteTime = microtime( true );
 841                 }
 842
 843                 // Add trace comment to the begin of the sql string, right after the operator.
 844                 // Or, for one-word queries (like "BEGIN" or COMMIT") add it to the end (bug 42598)
 845                 $commentedSql = preg_replace( '/\s|$/', " /* $fname {$this->agent} */ ", $sql, 1 );
 846
 847                 # Start implicit transactions that wrap the request if DBO_TRX is enabled
 848                 if ( !$this->mTrxLevel && $this->getFlag( self::DBO_TRX )
 849                         && $this->isTransactableQuery( $sql )
 850                 ) {
 851                         $this->begin( __METHOD__ . " ($fname)", self::TRANSACTION_INTERNAL );
 852                         $this->mTrxAutomatic = true;
 853                 }
 854
 855                 # Keep track of whether the transaction has write queries pending
 856                 if ( $this->mTrxLevel && !$this->mTrxDoneWrites && $isWrite ) {
 857                         $this->mTrxDoneWrites = true;
 858                         $this->trxProfiler->transactionWritingIn(
 859                                 $this->mServer, $this->mDBname, $this->mTrxShortId );
 860                 }
 861
 862                 if ( $this->getFlag( self::DBO_DEBUG ) ) {
 863                         $this->queryLogger->debug( "{$this->mDBname} {$commentedSql}" );
 864                 }
 865
 866                 # Avoid fatals if close() was called
 867                 $this->assertOpen();
 868
 869                 # Send the query to the server
 870                 $ret = $this->doProfiledQuery( $sql, $commentedSql, $isWrite, $fname );
 871
 872                 # Try reconnecting if the connection was lost
 873                 if ( false === $ret && $this->wasErrorReissuable() ) {
 874                         $recoverable = $this->canRecoverFromDisconnect( $sql, $priorWritesPending );
 875                         # Stash the last error values before anything might clear them
 876                         $lastError = $this->lastError();
 877                         $lastErrno = $this->lastErrno();
 878                         # Update state tracking to reflect transaction loss due to disconnection
 879                         $this->handleSessionLoss();
 880                         if ( $this->reconnect() ) {
 881                                 $msg = __METHOD__ . ": lost connection to {$this->getServer()}; reconnected";
 882                                 $this->connLogger->warning( $msg );
 883                                 $this->queryLogger->warning(
 884                                         "$msg:\n" . ( new RuntimeException() )->getTraceAsString() );
 885
 886                                 if ( !$recoverable ) {
 887                                         # Callers may catch the exception and continue to use the DB
 888                                         $this->reportQueryError( $lastError, $lastErrno, $sql, $fname );
 889                                 } else {
 890                                         # Should be safe to silently retry the query
 891                                         $ret = $this->doProfiledQuery( $sql, $commentedSql, $isWrite, $fname );
 892                                 }
 893                         } else {
 894                                 $msg = __METHOD__ . ": lost connection to {$this->getServer()} permanently";
 895                                 $this->connLogger->error( $msg );
 896                         }
 897                 }
 898
 899                 if ( false === $ret ) {
 900                         # Deadlocks cause the entire transaction to abort, not just the statement.
 901                         # https://dev.mysql.com/doc/refman/5.7/en/innodb-error-handling.html
 902                         # https://www.postgresql.org/docs/9.1/static/explicit-locking.html
 903                         if ( $this->wasDeadlock() ) {
 904                                 if ( $this->explicitTrxActive() || $priorWritesPending ) {
 905                                         $tempIgnore = false; // not recoverable
 906                                 }
 907                                 # Update state tracking to reflect transaction loss
 908                                 $this->handleSessionLoss();
 909                         }
 910
 911                         $this->reportQueryError(
 912                                 $this->lastError(), $this->lastErrno(), $sql, $fname, $tempIgnore );
 913                 }
 914
 915                 $res = $this->resultObject( $ret );
 916
 917                 return $res;
 918         }
 919
 920         private function doProfiledQuery( $sql, $commentedSql, $isWrite, $fname ) {
 921                 $isMaster = !is_null( $this->getLBInfo( 'master' ) );
 922                 # generalizeSQL() will probably cut down the query to reasonable
 923                 # logging size most of the time. The substr is really just a sanity check.
 924                 if ( $isMaster ) {
 925                         $queryProf = 'query-m: ' . substr( self::generalizeSQL( $sql ), 0, 255 );
 926                 } else {
 927                         $queryProf = 'query: ' . substr( self::generalizeSQL( $sql ), 0, 255 );
 928                 }
 929
 930                 # Include query transaction state
 931                 $queryProf .= $this->mTrxShortId ? " [TRX#{$this->mTrxShortId}]" : "";
 932
 933                 $startTime = microtime( true );
 934                 if ( $this->profiler ) {
 935                         call_user_func( [ $this->profiler, 'profileIn' ], $queryProf );
 936                 }
 937                 $ret = $this->doQuery( $commentedSql );
 938                 if ( $this->profiler ) {
 939                         call_user_func( [ $this->profiler, 'profileOut' ], $queryProf );
 940                 }
 941                 $queryRuntime = max( microtime( true ) - $startTime, 0.0 );
 942
 943                 unset( $queryProfSection ); // profile out (if set)
 944
 945                 if ( $ret !== false ) {
 946                         $this->lastPing = $startTime;
 947                         if ( $isWrite && $this->mTrxLevel ) {
 948                                 $this->updateTrxWriteQueryTime( $sql, $queryRuntime );
 949                                 $this->mTrxWriteCallers[] = $fname;
 950                         }
 951                 }
 952
 953                 if ( $sql === self::PING_QUERY ) {
 954                         $this->mRTTEstimate = $queryRuntime;
 955                 }
 956
 957                 $this->trxProfiler->recordQueryCompletion(
 958                         $queryProf, $startTime, $isWrite, $this->affectedRows()
 959                 );
 960                 $this->queryLogger->debug( $sql, [
 961                         'method' => $fname,
 962                         'master' => $isMaster,
 963                         'runtime' => $queryRuntime,
 964                 ] );
 965
 966                 return $ret;
 967         }
 968
 969         /**
 970          * Update the estimated run-time of a query, not counting large row lock times
 971          *
 972          * LoadBalancer can be set to rollback transactions that will create huge replication
 973          * lag. It bases this estimate off of pendingWriteQueryDuration(). Certain simple
 974          * queries, like inserting a row can take a long time due to row locking. This method
 975          * uses some simple heuristics to discount those cases.
 976          *
 977          * @param string $sql A SQL write query
 978          * @param float $runtime Total runtime, including RTT
 979          */
 980         private function updateTrxWriteQueryTime( $sql, $runtime ) {
 981                 // Whether this is indicative of replica DB runtime (except for RBR or ws_repl)
 982                 $indicativeOfReplicaRuntime = true;
 983                 if ( $runtime > self::SLOW_WRITE_SEC ) {
 984                         $verb = $this->getQueryVerb( $sql );
 985                         // insert(), upsert(), replace() are fast unless bulky in size or blocked on locks
 986                         if ( $verb === 'INSERT' ) {
 987                                 $indicativeOfReplicaRuntime = $this->affectedRows() > self::SMALL_WRITE_ROWS;
 988                         } elseif ( $verb === 'REPLACE' ) {
 989                                 $indicativeOfReplicaRuntime = $this->affectedRows() > self::SMALL_WRITE_ROWS / 2;
 990                         }
 991                 }
 992
 993                 $this->mTrxWriteDuration += $runtime;
 994                 $this->mTrxWriteQueryCount += 1;
 995                 if ( $indicativeOfReplicaRuntime ) {
 996                         $this->mTrxWriteAdjDuration += $runtime;
 997                         $this->mTrxWriteAdjQueryCount += 1;
 998                 }
 999         }
1000
1001         private function canRecoverFromDisconnect( $sql, $priorWritesPending ) {
1002                 # Transaction dropped; this can mean lost writes, or REPEATABLE-READ snapshots.
1003                 # Dropped connections also mean that named locks are automatically released.
1004                 # Only allow error suppression in autocommit mode or when the lost transaction
1005                 # didn't matter anyway (aside from DBO_TRX snapshot loss).
1006                 if ( $this->mNamedLocksHeld ) {
1007                         return false; // possible critical section violation
1008                 } elseif ( $sql === 'COMMIT' ) {
1009                         return !$priorWritesPending; // nothing written anyway? (T127428)
1010                 } elseif ( $sql === 'ROLLBACK' ) {
1011                         return true; // transaction lost...which is also what was requested :)
1012                 } elseif ( $this->explicitTrxActive() ) {
1013                         return false; // don't drop atomocity
1014                 } elseif ( $priorWritesPending ) {
1015                         return false; // prior writes lost from implicit transaction
1016                 }
1017
1018                 return true;
1019         }
1020
1021         private function handleSessionLoss() {
1022                 $this->mTrxLevel = 0;
1023                 $this->mTrxIdleCallbacks = []; // bug 65263
1024                 $this->mTrxPreCommitCallbacks = []; // bug 65263
1025                 $this->mSessionTempTables = [];
1026                 $this->mNamedLocksHeld = [];
1027                 try {
1028                         // Handle callbacks in mTrxEndCallbacks
1029                         $this->runOnTransactionIdleCallbacks( self::TRIGGER_ROLLBACK );
1030                         $this->runTransactionListenerCallbacks( self::TRIGGER_ROLLBACK );
1031                         return null;
1032                 } catch ( Exception $e ) {
1033                         // Already logged; move on...
1034                         return $e;
1035                 }
1036         }
1037
1038         public function reportQueryError( $error, $errno, $sql, $fname, $tempIgnore = false ) {
1039                 if ( $this->ignoreErrors() || $tempIgnore ) {
1040                         $this->queryLogger->debug( "SQL ERROR (ignored): $error\n" );
1041                 } else {
1042                         $sql1line = mb_substr( str_replace( "\n", "\\n", $sql ), 0, 5 * 1024 );
1043                         $this->queryLogger->error(
1044                                 "{fname}\t{db_server}\t{errno}\t{error}\t{sql1line}",
1045                                 $this->getLogContext( [
1046                                         'method' => __METHOD__,
1047                                         'errno' => $errno,
1048                                         'error' => $error,
1049                                         'sql1line' => $sql1line,
1050                                         'fname' => $fname,
1051                                 ] )
1052                         );
1053                         $this->queryLogger->debug( "SQL ERROR: " . $error . "\n" );
1054                         throw new DBQueryError( $this, $error, $errno, $sql, $fname );
1055                 }
1056         }
1057
1058         public function freeResult( $res ) {
1059         }
1060
1061         public function selectField(
1062                 $table, $var, $cond = '', $fname = __METHOD__, $options = []
1063         ) {
1064                 if ( $var === '*' ) { // sanity
1065                         throw new DBUnexpectedError( $this, "Cannot use a * field: got '$var'" );
1066                 }
1067
1068                 if ( !is_array( $options ) ) {
1069                         $options = [ $options ];
1070                 }
1071
1072                 $options['LIMIT'] = 1;
1073
1074                 $res = $this->select( $table, $var, $cond, $fname, $options );
1075                 if ( $res === false || !$this->numRows( $res ) ) {
1076                         return false;
1077                 }
1078
1079                 $row = $this->fetchRow( $res );
1080
1081                 if ( $row !== false ) {
1082                         return reset( $row );
1083                 } else {
1084                         return false;
1085                 }
1086         }
1087
1088         public function selectFieldValues(
1089                 $table, $var, $cond = '', $fname = __METHOD__, $options = [], $join_conds = []
1090         ) {
1091                 if ( $var === '*' ) { // sanity
1092                         throw new DBUnexpectedError( $this, "Cannot use a * field" );
1093                 } elseif ( !is_string( $var ) ) { // sanity
1094                         throw new DBUnexpectedError( $this, "Cannot use an array of fields" );
1095                 }
1096
1097                 if ( !is_array( $options ) ) {
1098                         $options = [ $options ];
1099                 }
1100
1101                 $res = $this->select( $table, $var, $cond, $fname, $options, $join_conds );
1102                 if ( $res === false ) {
1103                         return false;
1104                 }
1105
1106                 $values = [];
1107                 foreach ( $res as $row ) {
1108                         $values[] = $row->$var;
1109                 }
1110
1111                 return $values;
1112         }
1113
1114         /**
1115          * Returns an optional USE INDEX clause to go after the table, and a
1116          * string to go at the end of the query.
1117          *
1118          * @param array $options Associative array of options to be turned into
1119          *   an SQL query, valid keys are listed in the function.
1120          * @return array
1121          * @see Database::select()
1122          */
1123         protected function makeSelectOptions( $options ) {
1124                 $preLimitTail = $postLimitTail = '';
1125                 $startOpts = '';
1126
1127                 $noKeyOptions = [];
1128
1129                 foreach ( $options as $key => $option ) {
1130                         if ( is_numeric( $key ) ) {
1131                                 $noKeyOptions[$option] = true;
1132                         }
1133                 }
1134
1135                 $preLimitTail .= $this->makeGroupByWithHaving( $options );
1136
1137                 $preLimitTail .= $this->makeOrderBy( $options );
1138
1139                 // if (isset($options['LIMIT'])) {
1140                 //      $tailOpts .= $this->limitResult('', $options['LIMIT'],
1141                 //              isset($options['OFFSET']) ? $options['OFFSET']
1142                 //              : false);
1143                 // }
1144
1145                 if ( isset( $noKeyOptions['FOR UPDATE'] ) ) {
1146                         $postLimitTail .= ' FOR UPDATE';
1147                 }
1148
1149                 if ( isset( $noKeyOptions['LOCK IN SHARE MODE'] ) ) {
1150                         $postLimitTail .= ' LOCK IN SHARE MODE';
1151                 }
1152
1153                 if ( isset( $noKeyOptions['DISTINCT'] ) || isset( $noKeyOptions['DISTINCTROW'] ) ) {
1154                         $startOpts .= 'DISTINCT';
1155                 }
1156
1157                 # Various MySQL extensions
1158                 if ( isset( $noKeyOptions['STRAIGHT_JOIN'] ) ) {
1159                         $startOpts .= ' /*! STRAIGHT_JOIN */';
1160                 }
1161
1162                 if ( isset( $noKeyOptions['HIGH_PRIORITY'] ) ) {
1163                         $startOpts .= ' HIGH_PRIORITY';
1164                 }
1165
1166                 if ( isset( $noKeyOptions['SQL_BIG_RESULT'] ) ) {
1167                         $startOpts .= ' SQL_BIG_RESULT';
1168                 }
1169
1170                 if ( isset( $noKeyOptions['SQL_BUFFER_RESULT'] ) ) {
1171                         $startOpts .= ' SQL_BUFFER_RESULT';
1172                 }
1173
1174                 if ( isset( $noKeyOptions['SQL_SMALL_RESULT'] ) ) {
1175                         $startOpts .= ' SQL_SMALL_RESULT';
1176                 }
1177
1178                 if ( isset( $noKeyOptions['SQL_CALC_FOUND_ROWS'] ) ) {
1179                         $startOpts .= ' SQL_CALC_FOUND_ROWS';
1180                 }
1181
1182                 if ( isset( $noKeyOptions['SQL_CACHE'] ) ) {
1183                         $startOpts .= ' SQL_CACHE';
1184                 }
1185
1186                 if ( isset( $noKeyOptions['SQL_NO_CACHE'] ) ) {
1187                         $startOpts .= ' SQL_NO_CACHE';
1188                 }
1189
1190                 if ( isset( $options['USE INDEX'] ) && is_string( $options['USE INDEX'] ) ) {
1191                         $useIndex = $this->useIndexClause( $options['USE INDEX'] );
1192                 } else {
1193                         $useIndex = '';
1194                 }
1195                 if ( isset( $options['IGNORE INDEX'] ) && is_string( $options['IGNORE INDEX'] ) ) {
1196                         $ignoreIndex = $this->ignoreIndexClause( $options['IGNORE INDEX'] );
1197                 } else {
1198                         $ignoreIndex = '';
1199                 }
1200
1201                 return [ $startOpts, $useIndex, $preLimitTail, $postLimitTail, $ignoreIndex ];
1202         }
1203
1204         /**
1205          * Returns an optional GROUP BY with an optional HAVING
1206          *
1207          * @param array $options Associative array of options
1208          * @return string
1209          * @see Database::select()
1210          * @since 1.21
1211          */
1212         protected function makeGroupByWithHaving( $options ) {
1213                 $sql = '';
1214                 if ( isset( $options['GROUP BY'] ) ) {
1215                         $gb = is_array( $options['GROUP BY'] )
1216                                 ? implode( ',', $options['GROUP BY'] )
1217                                 : $options['GROUP BY'];
1218                         $sql .= ' GROUP BY ' . $gb;
1219                 }
1220                 if ( isset( $options['HAVING'] ) ) {
1221                         $having = is_array( $options['HAVING'] )
1222                                 ? $this->makeList( $options['HAVING'], self::LIST_AND )
1223                                 : $options['HAVING'];
1224                         $sql .= ' HAVING ' . $having;
1225                 }
1226
1227                 return $sql;
1228         }
1229
1230         /**
1231          * Returns an optional ORDER BY
1232          *
1233          * @param array $options Associative array of options
1234          * @return string
1235          * @see Database::select()
1236          * @since 1.21
1237          */
1238         protected function makeOrderBy( $options ) {
1239                 if ( isset( $options['ORDER BY'] ) ) {
1240                         $ob = is_array( $options['ORDER BY'] )
1241                                 ? implode( ',', $options['ORDER BY'] )
1242                                 : $options['ORDER BY'];
1243
1244                         return ' ORDER BY ' . $ob;
1245                 }
1246
1247                 return '';
1248         }
1249
1250         public function select( $table, $vars, $conds = '', $fname = __METHOD__,
1251                 $options = [], $join_conds = [] ) {
1252                 $sql = $this->selectSQLText( $table, $vars, $conds, $fname, $options, $join_conds );
1253
1254                 return $this->query( $sql, $fname );
1255         }
1256
1257         public function selectSQLText( $table, $vars, $conds = '', $fname = __METHOD__,
1258                 $options = [], $join_conds = []
1259         ) {
1260                 if ( is_array( $vars ) ) {
1261                         $vars = implode( ',', $this->fieldNamesWithAlias( $vars ) );
1262                 }
1263
1264                 $options = (array)$options;
1265                 $useIndexes = ( isset( $options['USE INDEX'] ) && is_array( $options['USE INDEX'] ) )
1266                         ? $options['USE INDEX']
1267                         : [];
1268                 $ignoreIndexes = (
1269                         isset( $options['IGNORE INDEX'] ) &&
1270                         is_array( $options['IGNORE INDEX'] )
1271                 )
1272                         ? $options['IGNORE INDEX']
1273                         : [];
1274
1275                 if ( is_array( $table ) ) {
1276                         $from = ' FROM ' .
1277                                 $this->tableNamesWithIndexClauseOrJOIN(
1278                                         $table, $useIndexes, $ignoreIndexes, $join_conds );
1279                 } elseif ( $table != '' ) {
1280                         if ( $table[0] == ' ' ) {
1281                                 $from = ' FROM ' . $table;
1282                         } else {
1283                                 $from = ' FROM ' .
1284                                         $this->tableNamesWithIndexClauseOrJOIN(
1285                                                 [ $table ], $useIndexes, $ignoreIndexes, [] );
1286                         }
1287                 } else {
1288                         $from = '';
1289                 }
1290
1291                 list( $startOpts, $useIndex, $preLimitTail, $postLimitTail, $ignoreIndex ) =
1292                         $this->makeSelectOptions( $options );
1293
1294                 if ( !empty( $conds ) ) {
1295                         if ( is_array( $conds ) ) {
1296                                 $conds = $this->makeList( $conds, self::LIST_AND );
1297                         }
1298                         $sql = "SELECT $startOpts $vars $from $useIndex $ignoreIndex " .
1299                                 "WHERE $conds $preLimitTail";
1300                 } else {
1301                         $sql = "SELECT $startOpts $vars $from $useIndex $ignoreIndex $preLimitTail";
1302                 }
1303
1304                 if ( isset( $options['LIMIT'] ) ) {
1305                         $sql = $this->limitResult( $sql, $options['LIMIT'],
1306                                 isset( $options['OFFSET'] ) ? $options['OFFSET'] : false );
1307                 }
1308                 $sql = "$sql $postLimitTail";
1309
1310                 if ( isset( $options['EXPLAIN'] ) ) {
1311                         $sql = 'EXPLAIN ' . $sql;
1312                 }
1313
1314                 return $sql;
1315         }
1316
1317         public function selectRow( $table, $vars, $conds, $fname = __METHOD__,
1318                 $options = [], $join_conds = []
1319         ) {
1320                 $options = (array)$options;
1321                 $options['LIMIT'] = 1;
1322                 $res = $this->select( $table, $vars, $conds, $fname, $options, $join_conds );
1323
1324                 if ( $res === false ) {
1325                         return false;
1326                 }
1327
1328                 if ( !$this->numRows( $res ) ) {
1329                         return false;
1330                 }
1331
1332                 $obj = $this->fetchObject( $res );
1333
1334                 return $obj;
1335         }
1336
1337         public function estimateRowCount(
1338                 $table, $vars = '*', $conds = '', $fname = __METHOD__, $options = []
1339         ) {
1340                 $rows = 0;
1341                 $res = $this->select( $table, [ 'rowcount' => 'COUNT(*)' ], $conds, $fname, $options );
1342
1343                 if ( $res ) {
1344                         $row = $this->fetchRow( $res );
1345                         $rows = ( isset( $row['rowcount'] ) ) ? (int)$row['rowcount'] : 0;
1346                 }
1347
1348                 return $rows;
1349         }
1350
1351         public function selectRowCount(
1352                 $tables, $vars = '*', $conds = '', $fname = __METHOD__, $options = [], $join_conds = []
1353         ) {
1354                 $rows = 0;
1355                 $sql = $this->selectSQLText( $tables, '1', $conds, $fname, $options, $join_conds );
1356                 $res = $this->query( "SELECT COUNT(*) AS rowcount FROM ($sql) tmp_count", $fname );
1357
1358                 if ( $res ) {
1359                         $row = $this->fetchRow( $res );
1360                         $rows = ( isset( $row['rowcount'] ) ) ? (int)$row['rowcount'] : 0;
1361                 }
1362
1363                 return $rows;
1364         }
1365
1366         /**
1367          * Removes most variables from an SQL query and replaces them with X or N for numbers.
1368          * It's only slightly flawed. Don't use for anything important.
1369          *
1370          * @param string $sql A SQL Query
1371          *
1372          * @return string
1373          */
1374         protected static function generalizeSQL( $sql ) {
1375                 # This does the same as the regexp below would do, but in such a way
1376                 # as to avoid crashing php on some large strings.
1377                 # $sql = preg_replace( "/'([^\\\\']|\\\\.)*'|\"([^\\\\\"]|\\\\.)*\"/", "'X'", $sql );
1378
1379                 $sql = str_replace( "\\\\", '', $sql );
1380                 $sql = str_replace( "\\'", '', $sql );
1381                 $sql = str_replace( "\\\"", '', $sql );
1382                 $sql = preg_replace( "/'.*'/s", "'X'", $sql );
1383                 $sql = preg_replace( '/".*"/s', "'X'", $sql );
1384
1385                 # All newlines, tabs, etc replaced by single space
1386                 $sql = preg_replace( '/\s+/', ' ', $sql );
1387
1388                 # All numbers => N,
1389                 # except the ones surrounded by characters, e.g. l10n
1390                 $sql = preg_replace( '/-?\d+(,-?\d+)+/s', 'N,...,N', $sql );
1391                 $sql = preg_replace( '/(?<![a-zA-Z])-?\d+(?![a-zA-Z])/s', 'N', $sql );
1392
1393                 return $sql;
1394         }
1395
1396         public function fieldExists( $table, $field, $fname = __METHOD__ ) {
1397                 $info = $this->fieldInfo( $table, $field );
1398
1399                 return (bool)$info;
1400         }
1401
1402         public function indexExists( $table, $index, $fname = __METHOD__ ) {
1403                 if ( !$this->tableExists( $table ) ) {
1404                         return null;
1405                 }
1406
1407                 $info = $this->indexInfo( $table, $index, $fname );
1408                 if ( is_null( $info ) ) {
1409                         return null;
1410                 } else {
1411                         return $info !== false;
1412                 }
1413         }
1414
1415         public function tableExists( $table, $fname = __METHOD__ ) {
1416                 $tableRaw = $this->tableName( $table, 'raw' );
1417                 if ( isset( $this->mSessionTempTables[$tableRaw] ) ) {
1418                         return true; // already known to exist
1419                 }
1420
1421                 $table = $this->tableName( $table );
1422                 $old = $this->ignoreErrors( true );
1423                 $res = $this->query( "SELECT 1 FROM $table LIMIT 1", $fname );
1424                 $this->ignoreErrors( $old );
1425
1426                 return (bool)$res;
1427         }
1428
1429         public function indexUnique( $table, $index ) {
1430                 $indexInfo = $this->indexInfo( $table, $index );
1431
1432                 if ( !$indexInfo ) {
1433                         return null;
1434                 }
1435
1436                 return !$indexInfo[0]->Non_unique;
1437         }
1438
1439         /**
1440          * Helper for Database::insert().
1441          *
1442          * @param array $options
1443          * @return string
1444          */
1445         protected function makeInsertOptions( $options ) {
1446                 return implode( ' ', $options );
1447         }
1448
1449         public function insert( $table, $a, $fname = __METHOD__, $options = [] ) {
1450                 # No rows to insert, easy just return now
1451                 if ( !count( $a ) ) {
1452                         return true;
1453                 }
1454
1455                 $table = $this->tableName( $table );
1456
1457                 if ( !is_array( $options ) ) {
1458                         $options = [ $options ];
1459                 }
1460
1461                 $fh = null;
1462                 if ( isset( $options['fileHandle'] ) ) {
1463                         $fh = $options['fileHandle'];
1464                 }
1465                 $options = $this->makeInsertOptions( $options );
1466
1467                 if ( isset( $a[0] ) && is_array( $a[0] ) ) {
1468                         $multi = true;
1469                         $keys = array_keys( $a[0] );
1470                 } else {
1471                         $multi = false;
1472                         $keys = array_keys( $a );
1473                 }
1474
1475                 $sql = 'INSERT ' . $options .
1476                         " INTO $table (" . implode( ',', $keys ) . ') VALUES ';
1477
1478                 if ( $multi ) {
1479                         $first = true;
1480                         foreach ( $a as $row ) {
1481                                 if ( $first ) {
1482                                         $first = false;
1483                                 } else {
1484                                         $sql .= ',';
1485                                 }
1486                                 $sql .= '(' . $this->makeList( $row ) . ')';
1487                         }
1488                 } else {
1489                         $sql .= '(' . $this->makeList( $a ) . ')';
1490                 }
1491
1492                 if ( $fh !== null && false === fwrite( $fh, $sql ) ) {
1493                         return false;
1494                 } elseif ( $fh !== null ) {
1495                         return true;
1496                 }
1497
1498                 return (bool)$this->query( $sql, $fname );
1499         }
1500
1501         /**
1502          * Make UPDATE options array for Database::makeUpdateOptions
1503          *
1504          * @param array $options
1505          * @return array
1506          */
1507         protected function makeUpdateOptionsArray( $options ) {
1508                 if ( !is_array( $options ) ) {
1509                         $options = [ $options ];
1510                 }
1511
1512                 $opts = [];
1513
1514                 if ( in_array( 'IGNORE', $options ) ) {
1515                         $opts[] = 'IGNORE';
1516                 }
1517
1518                 return $opts;
1519         }
1520
1521         /**
1522          * Make UPDATE options for the Database::update function
1523          *
1524          * @param array $options The options passed to Database::update
1525          * @return string
1526          */
1527         protected function makeUpdateOptions( $options ) {
1528                 $opts = $this->makeUpdateOptionsArray( $options );
1529
1530                 return implode( ' ', $opts );
1531         }
1532
1533         public function update( $table, $values, $conds, $fname = __METHOD__, $options = [] ) {
1534                 $table = $this->tableName( $table );
1535                 $opts = $this->makeUpdateOptions( $options );
1536                 $sql = "UPDATE $opts $table SET " . $this->makeList( $values, self::LIST_SET );
1537
1538                 if ( $conds !== [] && $conds !== '*' ) {
1539                         $sql .= " WHERE " . $this->makeList( $conds, self::LIST_AND );
1540                 }
1541
1542                 return $this->query( $sql, $fname );
1543         }
1544
1545         public function makeList( $a, $mode = self::LIST_COMMA ) {
1546                 if ( !is_array( $a ) ) {
1547                         throw new DBUnexpectedError( $this, __METHOD__ . ' called with incorrect parameters' );
1548                 }
1549
1550                 $first = true;
1551                 $list = '';
1552
1553                 foreach ( $a as $field => $value ) {
1554                         if ( !$first ) {
1555                                 if ( $mode == self::LIST_AND ) {
1556                                         $list .= ' AND ';
1557                                 } elseif ( $mode == self::LIST_OR ) {
1558                                         $list .= ' OR ';
1559                                 } else {
1560                                         $list .= ',';
1561                                 }
1562                         } else {
1563                                 $first = false;
1564                         }
1565
1566                         if ( ( $mode == self::LIST_AND || $mode == self::LIST_OR ) && is_numeric( $field ) ) {
1567                                 $list .= "($value)";
1568                         } elseif ( $mode == self::LIST_SET && is_numeric( $field ) ) {
1569                                 $list .= "$value";
1570                         } elseif (
1571                                 ( $mode == self::LIST_AND || $mode == self::LIST_OR ) && is_array( $value )
1572                         ) {
1573                                 // Remove null from array to be handled separately if found
1574                                 $includeNull = false;
1575                                 foreach ( array_keys( $value, null, true ) as $nullKey ) {
1576                                         $includeNull = true;
1577                                         unset( $value[$nullKey] );
1578                                 }
1579                                 if ( count( $value ) == 0 && !$includeNull ) {
1580                                         throw new InvalidArgumentException(
1581                                                 __METHOD__ . ": empty input for field $field" );
1582                                 } elseif ( count( $value ) == 0 ) {
1583                                         // only check if $field is null
1584                                         $list .= "$field IS NULL";
1585                                 } else {
1586                                         // IN clause contains at least one valid element
1587                                         if ( $includeNull ) {
1588                                                 // Group subconditions to ensure correct precedence
1589                                                 $list .= '(';
1590                                         }
1591                                         if ( count( $value ) == 1 ) {
1592                                                 // Special-case single values, as IN isn't terribly efficient
1593                                                 // Don't necessarily assume the single key is 0; we don't
1594                                                 // enforce linear numeric ordering on other arrays here.
1595                                                 $value = array_values( $value )[0];
1596                                                 $list .= $field . " = " . $this->addQuotes( $value );
1597                                         } else {
1598                                                 $list .= $field . " IN (" . $this->makeList( $value ) . ") ";
1599                                         }
1600                                         // if null present in array, append IS NULL
1601                                         if ( $includeNull ) {
1602                                                 $list .= " OR $field IS NULL)";
1603                                         }
1604                                 }
1605                         } elseif ( $value === null ) {
1606                                 if ( $mode == self::LIST_AND || $mode == self::LIST_OR ) {
1607                                         $list .= "$field IS ";
1608                                 } elseif ( $mode == self::LIST_SET ) {
1609                                         $list .= "$field = ";
1610                                 }
1611                                 $list .= 'NULL';
1612                         } else {
1613                                 if (
1614                                         $mode == self::LIST_AND || $mode == self::LIST_OR || $mode == self::LIST_SET
1615                                 ) {
1616                                         $list .= "$field = ";
1617                                 }
1618                                 $list .= $mode == self::LIST_NAMES ? $value : $this->addQuotes( $value );
1619                         }
1620                 }
1621
1622                 return $list;
1623         }
1624
1625         public function makeWhereFrom2d( $data, $baseKey, $subKey ) {
1626                 $conds = [];
1627
1628                 foreach ( $data as $base => $sub ) {
1629                         if ( count( $sub ) ) {
1630                                 $conds[] = $this->makeList(
1631                                         [ $baseKey => $base, $subKey => array_keys( $sub ) ],
1632                                         self::LIST_AND );
1633                         }
1634                 }
1635
1636                 if ( $conds ) {
1637                         return $this->makeList( $conds, self::LIST_OR );
1638                 } else {
1639                         // Nothing to search for...
1640                         return false;
1641                 }
1642         }
1643
1644         public function aggregateValue( $valuedata, $valuename = 'value' ) {
1645                 return $valuename;
1646         }
1647
1648         public function bitNot( $field ) {
1649                 return "(~$field)";
1650         }
1651
1652         public function bitAnd( $fieldLeft, $fieldRight ) {
1653                 return "($fieldLeft & $fieldRight)";
1654         }
1655
1656         public function bitOr( $fieldLeft, $fieldRight ) {
1657                 return "($fieldLeft | $fieldRight)";
1658         }
1659
1660         public function buildConcat( $stringList ) {
1661                 return 'CONCAT(' . implode( ',', $stringList ) . ')';
1662         }
1663
1664         public function buildGroupConcatField(
1665                 $delim, $table, $field, $conds = '', $join_conds = []
1666         ) {
1667                 $fld = "GROUP_CONCAT($field SEPARATOR " . $this->addQuotes( $delim ) . ')';
1668
1669                 return '(' . $this->selectSQLText( $table, $fld, $conds, null, [], $join_conds ) . ')';
1670         }
1671
1672         public function buildStringCast( $field ) {
1673                 return $field;
1674         }
1675
1676         public function selectDB( $db ) {
1677                 # Stub. Shouldn't cause serious problems if it's not overridden, but
1678                 # if your database engine supports a concept similar to MySQL's
1679                 # databases you may as well.
1680                 $this->mDBname = $db;
1681
1682                 return true;
1683         }
1684
1685         public function getDBname() {
1686                 return $this->mDBname;
1687         }
1688
1689         public function getServer() {
1690                 return $this->mServer;
1691         }
1692
1693         public function tableName( $name, $format = 'quoted' ) {
1694                 # Skip the entire process when we have a string quoted on both ends.
1695                 # Note that we check the end so that we will still quote any use of
1696                 # use of `database`.table. But won't break things if someone wants
1697                 # to query a database table with a dot in the name.
1698                 if ( $this->isQuotedIdentifier( $name ) ) {
1699                         return $name;
1700                 }
1701
1702                 # Lets test for any bits of text that should never show up in a table
1703                 # name. Basically anything like JOIN or ON which are actually part of
1704                 # SQL queries, but may end up inside of the table value to combine
1705                 # sql. Such as how the API is doing.
1706                 # Note that we use a whitespace test rather than a \b test to avoid
1707                 # any remote case where a word like on may be inside of a table name
1708                 # surrounded by symbols which may be considered word breaks.
1709                 if ( preg_match( '/(^|\s)(DISTINCT|JOIN|ON|AS)(\s|$)/i', $name ) !== 0 ) {
1710                         return $name;
1711                 }
1712
1713                 # Split database and table into proper variables.
1714                 # We reverse the explode so that database.table and table both output
1715                 # the correct table.
1716                 $dbDetails = explode( '.', $name, 3 );
1717                 if ( count( $dbDetails ) == 3 ) {
1718                         list( $database, $schema, $table ) = $dbDetails;
1719                         # We don't want any prefix added in this case
1720                         $prefix = '';
1721                 } elseif ( count( $dbDetails ) == 2 ) {
1722                         list( $database, $table ) = $dbDetails;
1723                         # We don't want any prefix added in this case
1724                         $prefix = '';
1725                         # In dbs that support it, $database may actually be the schema
1726                         # but that doesn't affect any of the functionality here
1727                         $schema = '';
1728                 } else {
1729                         list( $table ) = $dbDetails;
1730                         if ( isset( $this->tableAliases[$table] ) ) {
1731                                 $database = $this->tableAliases[$table]['dbname'];
1732                                 $schema = is_string( $this->tableAliases[$table]['schema'] )
1733                                         ? $this->tableAliases[$table]['schema']
1734                                         : $this->mSchema;
1735                                 $prefix = is_string( $this->tableAliases[$table]['prefix'] )
1736                                         ? $this->tableAliases[$table]['prefix']
1737                                         : $this->mTablePrefix;
1738                         } else {
1739                                 $database = '';
1740                                 $schema = $this->mSchema; # Default schema
1741                                 $prefix = $this->mTablePrefix; # Default prefix
1742                         }
1743                 }
1744
1745                 # Quote $table and apply the prefix if not quoted.
1746                 # $tableName might be empty if this is called from Database::replaceVars()
1747                 $tableName = "{$prefix}{$table}";
1748                 if ( $format === 'quoted'
1749                         && !$this->isQuotedIdentifier( $tableName )
1750                         && $tableName !== ''
1751                 ) {
1752                         $tableName = $this->addIdentifierQuotes( $tableName );
1753                 }
1754
1755                 # Quote $schema and $database and merge them with the table name if needed
1756                 $tableName = $this->prependDatabaseOrSchema( $schema, $tableName, $format );
1757                 $tableName = $this->prependDatabaseOrSchema( $database, $tableName, $format );
1758
1759                 return $tableName;
1760         }
1761
1762         /**
1763          * @param string|null $namespace Database or schema
1764          * @param string $relation Name of table, view, sequence, etc...
1765          * @param string $format One of (raw, quoted)
1766          * @return string Relation name with quoted and merged $namespace as needed
1767          */
1768         private function prependDatabaseOrSchema( $namespace, $relation, $format ) {
1769                 if ( strlen( $namespace ) ) {
1770                         if ( $format === 'quoted' && !$this->isQuotedIdentifier( $namespace ) ) {
1771                                 $namespace = $this->addIdentifierQuotes( $namespace );
1772                         }
1773                         $relation = $namespace . '.' . $relation;
1774                 }
1775
1776                 return $relation;
1777         }
1778
1779         public function tableNames() {
1780                 $inArray = func_get_args();
1781                 $retVal = [];
1782
1783                 foreach ( $inArray as $name ) {
1784                         $retVal[$name] = $this->tableName( $name );
1785                 }
1786
1787                 return $retVal;
1788         }
1789
1790         public function tableNamesN() {
1791                 $inArray = func_get_args();
1792                 $retVal = [];
1793
1794                 foreach ( $inArray as $name ) {
1795                         $retVal[] = $this->tableName( $name );
1796                 }
1797
1798                 return $retVal;
1799         }
1800
1801         /**
1802          * Get an aliased table name
1803          * e.g. tableName AS newTableName
1804          *
1805          * @param string $name Table name, see tableName()
1806          * @param string|bool $alias Alias (optional)
1807          * @return string SQL name for aliased table. Will not alias a table to its own name
1808          */
1809         protected function tableNameWithAlias( $name, $alias = false ) {
1810                 if ( !$alias || $alias == $name ) {
1811                         return $this->tableName( $name );
1812                 } else {
1813                         return $this->tableName( $name ) . ' ' . $this->addIdentifierQuotes( $alias );
1814                 }
1815         }
1816
1817         /**
1818          * Gets an array of aliased table names
1819          *
1820          * @param array $tables [ [alias] => table ]
1821          * @return string[] See tableNameWithAlias()
1822          */
1823         protected function tableNamesWithAlias( $tables ) {
1824                 $retval = [];
1825                 foreach ( $tables as $alias => $table ) {
1826                         if ( is_numeric( $alias ) ) {
1827                                 $alias = $table;
1828                         }
1829                         $retval[] = $this->tableNameWithAlias( $table, $alias );
1830                 }
1831
1832                 return $retval;
1833         }
1834
1835         /**
1836          * Get an aliased field name
1837          * e.g. fieldName AS newFieldName
1838          *
1839          * @param string $name Field name
1840          * @param string|bool $alias Alias (optional)
1841          * @return string SQL name for aliased field. Will not alias a field to its own name
1842          */
1843         protected function fieldNameWithAlias( $name, $alias = false ) {
1844                 if ( !$alias || (string)$alias === (string)$name ) {
1845                         return $name;
1846                 } else {
1847                         return $name . ' AS ' . $this->addIdentifierQuotes( $alias ); // PostgreSQL needs AS
1848                 }
1849         }
1850
1851         /**
1852          * Gets an array of aliased field names
1853          *
1854          * @param array $fields [ [alias] => field ]
1855          * @return string[] See fieldNameWithAlias()
1856          */
1857         protected function fieldNamesWithAlias( $fields ) {
1858                 $retval = [];
1859                 foreach ( $fields as $alias => $field ) {
1860                         if ( is_numeric( $alias ) ) {
1861                                 $alias = $field;
1862                         }
1863                         $retval[] = $this->fieldNameWithAlias( $field, $alias );
1864                 }
1865
1866                 return $retval;
1867         }
1868
1869         /**
1870          * Get the aliased table name clause for a FROM clause
1871          * which might have a JOIN and/or USE INDEX or IGNORE INDEX clause
1872          *
1873          * @param array $tables ( [alias] => table )
1874          * @param array $use_index Same as for select()
1875          * @param array $ignore_index Same as for select()
1876          * @param array $join_conds Same as for select()
1877          * @return string
1878          */
1879         protected function tableNamesWithIndexClauseOrJOIN(
1880                 $tables, $use_index = [], $ignore_index = [], $join_conds = []
1881         ) {
1882                 $ret = [];
1883                 $retJOIN = [];
1884                 $use_index = (array)$use_index;
1885                 $ignore_index = (array)$ignore_index;
1886                 $join_conds = (array)$join_conds;
1887
1888                 foreach ( $tables as $alias => $table ) {
1889                         if ( !is_string( $alias ) ) {
1890                                 // No alias? Set it equal to the table name
1891                                 $alias = $table;
1892                         }
1893                         // Is there a JOIN clause for this table?
1894                         if ( isset( $join_conds[$alias] ) ) {
1895                                 list( $joinType, $conds ) = $join_conds[$alias];
1896                                 $tableClause = $joinType;
1897                                 $tableClause .= ' ' . $this->tableNameWithAlias( $table, $alias );
1898                                 if ( isset( $use_index[$alias] ) ) { // has USE INDEX?
1899                                         $use = $this->useIndexClause( implode( ',', (array)$use_index[$alias] ) );
1900                                         if ( $use != '' ) {
1901                                                 $tableClause .= ' ' . $use;
1902                                         }
1903                                 }
1904                                 if ( isset( $ignore_index[$alias] ) ) { // has IGNORE INDEX?
1905                                         $ignore = $this->ignoreIndexClause(
1906                                                 implode( ',', (array)$ignore_index[$alias] ) );
1907                                         if ( $ignore != '' ) {
1908                                                 $tableClause .= ' ' . $ignore;
1909                                         }
1910                                 }
1911                                 $on = $this->makeList( (array)$conds, self::LIST_AND );
1912                                 if ( $on != '' ) {
1913                                         $tableClause .= ' ON (' . $on . ')';
1914                                 }
1915
1916                                 $retJOIN[] = $tableClause;
1917                         } elseif ( isset( $use_index[$alias] ) ) {
1918                                 // Is there an INDEX clause for this table?
1919                                 $tableClause = $this->tableNameWithAlias( $table, $alias );
1920                                 $tableClause .= ' ' . $this->useIndexClause(
1921                                                 implode( ',', (array)$use_index[$alias] )
1922                                         );
1923
1924                                 $ret[] = $tableClause;
1925                         } elseif ( isset( $ignore_index[$alias] ) ) {
1926                                 // Is there an INDEX clause for this table?
1927                                 $tableClause = $this->tableNameWithAlias( $table, $alias );
1928                                 $tableClause .= ' ' . $this->ignoreIndexClause(
1929                                                 implode( ',', (array)$ignore_index[$alias] )
1930                                         );
1931
1932                                 $ret[] = $tableClause;
1933                         } else {
1934                                 $tableClause = $this->tableNameWithAlias( $table, $alias );
1935
1936                                 $ret[] = $tableClause;
1937                         }
1938                 }
1939
1940                 // We can't separate explicit JOIN clauses with ',', use ' ' for those
1941                 $implicitJoins = !empty( $ret ) ? implode( ',', $ret ) : "";
1942                 $explicitJoins = !empty( $retJOIN ) ? implode( ' ', $retJOIN ) : "";
1943
1944                 // Compile our final table clause
1945                 return implode( ' ', [ $implicitJoins, $explicitJoins ] );
1946         }
1947
1948         /**
1949          * Get the name of an index in a given table.
1950          *
1951          * @param string $index
1952          * @return string
1953          */
1954         protected function indexName( $index ) {
1955                 return $index;
1956         }
1957
1958         public function addQuotes( $s ) {
1959                 if ( $s instanceof Blob ) {
1960                         $s = $s->fetch();
1961                 }
1962                 if ( $s === null ) {
1963                         return 'NULL';
1964                 } elseif ( is_bool( $s ) ) {
1965                         return (int)$s;
1966                 } else {
1967                         # This will also quote numeric values. This should be harmless,
1968                         # and protects against weird problems that occur when they really
1969                         # _are_ strings such as article titles and string->number->string
1970                         # conversion is not 1:1.
1971                         return "'" . $this->strencode( $s ) . "'";
1972                 }
1973         }
1974
1975         /**
1976          * Quotes an identifier using `backticks` or "double quotes" depending on the database type.
1977          * MySQL uses `backticks` while basically everything else uses double quotes.
1978          * Since MySQL is the odd one out here the double quotes are our generic
1979          * and we implement backticks in DatabaseMysql.
1980          *
1981          * @param string $s
1982          * @return string
1983          */
1984         public function addIdentifierQuotes( $s ) {
1985                 return '"' . str_replace( '"', '""', $s ) . '"';
1986         }
1987
1988         /**
1989          * Returns if the given identifier looks quoted or not according to
1990          * the database convention for quoting identifiers .
1991          *
1992          * @note Do not use this to determine if untrusted input is safe.
1993          *   A malicious user can trick this function.
1994          * @param string $name
1995          * @return bool
1996          */
1997         public function isQuotedIdentifier( $name ) {
1998                 return $name[0] == '"' && substr( $name, -1, 1 ) == '"';
1999         }
2000
2001         /**
2002          * @param string $s
2003          * @return string
2004          */
2005         protected function escapeLikeInternal( $s ) {
2006                 return addcslashes( $s, '\%_' );
2007         }
2008
2009         public function buildLike() {
2010                 $params = func_get_args();
2011
2012                 if ( count( $params ) > 0 && is_array( $params[0] ) ) {
2013                         $params = $params[0];
2014                 }
2015
2016                 $s = '';
2017
2018                 foreach ( $params as $value ) {
2019                         if ( $value instanceof LikeMatch ) {
2020                                 $s .= $value->toString();
2021                         } else {
2022                                 $s .= $this->escapeLikeInternal( $value );
2023                         }
2024                 }
2025
2026                 return " LIKE {$this->addQuotes( $s )} ";
2027         }
2028
2029         public function anyChar() {
2030                 return new LikeMatch( '_' );
2031         }
2032
2033         public function anyString() {
2034                 return new LikeMatch( '%' );
2035         }
2036
2037         public function nextSequenceValue( $seqName ) {
2038                 return null;
2039         }
2040
2041         /**
2042          * USE 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 useIndexClause( $index ) {
2052                 return '';
2053         }
2054
2055         /**
2056          * IGNORE INDEX clause. Unlikely to be useful for anything but MySQL. This
2057          * is only needed because a) MySQL must be as efficient as possible due to
2058          * its use on Wikipedia, and b) MySQL 4.0 is kind of dumb sometimes about
2059          * which index to pick. Anyway, other databases might have different
2060          * indexes on a given table. So don't bother overriding this unless you're
2061          * MySQL.
2062          * @param string $index
2063          * @return string
2064          */
2065         public function ignoreIndexClause( $index ) {
2066                 return '';
2067         }
2068
2069         public function replace( $table, $uniqueIndexes, $rows, $fname = __METHOD__ ) {
2070                 $quotedTable = $this->tableName( $table );
2071
2072                 if ( count( $rows ) == 0 ) {
2073                         return;
2074                 }
2075
2076                 # Single row case
2077                 if ( !is_array( reset( $rows ) ) ) {
2078                         $rows = [ $rows ];
2079                 }
2080
2081                 // @FXIME: this is not atomic, but a trx would break affectedRows()
2082                 foreach ( $rows as $row ) {
2083                         # Delete rows which collide
2084                         if ( $uniqueIndexes ) {
2085                                 $sql = "DELETE FROM $quotedTable WHERE ";
2086                                 $first = true;
2087                                 foreach ( $uniqueIndexes as $index ) {
2088                                         if ( $first ) {
2089                                                 $first = false;
2090                                                 $sql .= '( ';
2091                                         } else {
2092                                                 $sql .= ' ) OR ( ';
2093                                         }
2094                                         if ( is_array( $index ) ) {
2095                                                 $first2 = true;
2096                                                 foreach ( $index as $col ) {
2097                                                         if ( $first2 ) {
2098                                                                 $first2 = false;
2099                                                         } else {
2100                                                                 $sql .= ' AND ';
2101                                                         }
2102                                                         $sql .= $col . '=' . $this->addQuotes( $row[$col] );
2103                                                 }
2104                                         } else {
2105                                                 $sql .= $index . '=' . $this->addQuotes( $row[$index] );
2106                                         }
2107                                 }
2108                                 $sql .= ' )';
2109                                 $this->query( $sql, $fname );
2110                         }
2111
2112                         # Now insert the row
2113                         $this->insert( $table, $row, $fname );
2114                 }
2115         }
2116
2117         /**
2118          * REPLACE query wrapper for MySQL and SQLite, which have a native REPLACE
2119          * statement.
2120          *
2121          * @param string $table Table name
2122          * @param array|string $rows Row(s) to insert
2123          * @param string $fname Caller function name
2124          *
2125          * @return ResultWrapper
2126          */
2127         protected function nativeReplace( $table, $rows, $fname ) {
2128                 $table = $this->tableName( $table );
2129
2130                 # Single row case
2131                 if ( !is_array( reset( $rows ) ) ) {
2132                         $rows = [ $rows ];
2133                 }
2134
2135                 $sql = "REPLACE INTO $table (" . implode( ',', array_keys( $rows[0] ) ) . ') VALUES ';
2136                 $first = true;
2137
2138                 foreach ( $rows as $row ) {
2139                         if ( $first ) {
2140                                 $first = false;
2141                         } else {
2142                                 $sql .= ',';
2143                         }
2144
2145                         $sql .= '(' . $this->makeList( $row ) . ')';
2146                 }
2147
2148                 return $this->query( $sql, $fname );
2149         }
2150
2151         public function upsert( $table, array $rows, array $uniqueIndexes, array $set,
2152                 $fname = __METHOD__
2153         ) {
2154                 if ( !count( $rows ) ) {
2155                         return true; // nothing to do
2156                 }
2157
2158                 if ( !is_array( reset( $rows ) ) ) {
2159                         $rows = [ $rows ];
2160                 }
2161
2162                 if ( count( $uniqueIndexes ) ) {
2163                         $clauses = []; // list WHERE clauses that each identify a single row
2164                         foreach ( $rows as $row ) {
2165                                 foreach ( $uniqueIndexes as $index ) {
2166                                         $index = is_array( $index ) ? $index : [ $index ]; // columns
2167                                         $rowKey = []; // unique key to this row
2168                                         foreach ( $index as $column ) {
2169                                                 $rowKey[$column] = $row[$column];
2170                                         }
2171                                         $clauses[] = $this->makeList( $rowKey, self::LIST_AND );
2172                                 }
2173                         }
2174                         $where = [ $this->makeList( $clauses, self::LIST_OR ) ];
2175                 } else {
2176                         $where = false;
2177                 }
2178
2179                 $useTrx = !$this->mTrxLevel;
2180                 if ( $useTrx ) {
2181                         $this->begin( $fname, self::TRANSACTION_INTERNAL );
2182                 }
2183                 try {
2184                         # Update any existing conflicting row(s)
2185                         if ( $where !== false ) {
2186                                 $ok = $this->update( $table, $set, $where, $fname );
2187                         } else {
2188                                 $ok = true;
2189                         }
2190                         # Now insert any non-conflicting row(s)
2191                         $ok = $this->insert( $table, $rows, $fname, [ 'IGNORE' ] ) && $ok;
2192                 } catch ( Exception $e ) {
2193                         if ( $useTrx ) {
2194                                 $this->rollback( $fname, self::FLUSHING_INTERNAL );
2195                         }
2196                         throw $e;
2197                 }
2198                 if ( $useTrx ) {
2199                         $this->commit( $fname, self::FLUSHING_INTERNAL );
2200                 }
2201
2202                 return $ok;
2203         }
2204
2205         public function deleteJoin( $delTable, $joinTable, $delVar, $joinVar, $conds,
2206                 $fname = __METHOD__
2207         ) {
2208                 if ( !$conds ) {
2209                         throw new DBUnexpectedError( $this, __METHOD__ . ' called with empty $conds' );
2210                 }
2211
2212                 $delTable = $this->tableName( $delTable );
2213                 $joinTable = $this->tableName( $joinTable );
2214                 $sql = "DELETE FROM $delTable WHERE $delVar IN (SELECT $joinVar FROM $joinTable ";
2215                 if ( $conds != '*' ) {
2216                         $sql .= 'WHERE ' . $this->makeList( $conds, self::LIST_AND );
2217                 }
2218                 $sql .= ')';
2219
2220                 $this->query( $sql, $fname );
2221         }
2222
2223         public function textFieldSize( $table, $field ) {
2224                 $table = $this->tableName( $table );
2225                 $sql = "SHOW COLUMNS FROM $table LIKE \"$field\";";
2226                 $res = $this->query( $sql, __METHOD__ );
2227                 $row = $this->fetchObject( $res );
2228
2229                 $m = [];
2230
2231                 if ( preg_match( '/\((.*)\)/', $row->Type, $m ) ) {
2232                         $size = $m[1];
2233                 } else {
2234                         $size = -1;
2235                 }
2236
2237                 return $size;
2238         }
2239
2240         public function delete( $table, $conds, $fname = __METHOD__ ) {
2241                 if ( !$conds ) {
2242                         throw new DBUnexpectedError( $this, __METHOD__ . ' called with no conditions' );
2243                 }
2244
2245                 $table = $this->tableName( $table );
2246                 $sql = "DELETE FROM $table";
2247
2248                 if ( $conds != '*' ) {
2249                         if ( is_array( $conds ) ) {
2250                                 $conds = $this->makeList( $conds, self::LIST_AND );
2251                         }
2252                         $sql .= ' WHERE ' . $conds;
2253                 }
2254
2255                 return $this->query( $sql, $fname );
2256         }
2257
2258         public function insertSelect(
2259                 $destTable, $srcTable, $varMap, $conds,
2260                 $fname = __METHOD__, $insertOptions = [], $selectOptions = []
2261         ) {
2262                 if ( $this->cliMode ) {
2263                         // For massive migrations with downtime, we don't want to select everything
2264                         // into memory and OOM, so do all this native on the server side if possible.
2265                         return $this->nativeInsertSelect(
2266                                 $destTable,
2267                                 $srcTable,
2268                                 $varMap,
2269                                 $conds,
2270                                 $fname,
2271                                 $insertOptions,
2272                                 $selectOptions
2273                         );
2274                 }
2275
2276                 // For web requests, do a locking SELECT and then INSERT. This puts the SELECT burden
2277                 // on only the master (without needing row-based-replication). It also makes it easy to
2278                 // know how big the INSERT is going to be.
2279                 $fields = [];
2280                 foreach ( $varMap as $dstColumn => $sourceColumnOrSql ) {
2281                         $fields[] = $this->fieldNameWithAlias( $sourceColumnOrSql, $dstColumn );
2282                 }
2283                 $selectOptions[] = 'FOR UPDATE';
2284                 $res = $this->select( $srcTable, implode( ',', $fields ), $conds, $fname, $selectOptions );
2285                 if ( !$res ) {
2286                         return false;
2287                 }
2288
2289                 $rows = [];
2290                 foreach ( $res as $row ) {
2291                         $rows[] = (array)$row;
2292                 }
2293
2294                 return $this->insert( $destTable, $rows, $fname, $insertOptions );
2295         }
2296
2297         protected function nativeInsertSelect( $destTable, $srcTable, $varMap, $conds,
2298                 $fname = __METHOD__,
2299                 $insertOptions = [], $selectOptions = []
2300         ) {
2301                 $destTable = $this->tableName( $destTable );
2302
2303                 if ( !is_array( $insertOptions ) ) {
2304                         $insertOptions = [ $insertOptions ];
2305                 }
2306
2307                 $insertOptions = $this->makeInsertOptions( $insertOptions );
2308
2309                 if ( !is_array( $selectOptions ) ) {
2310                         $selectOptions = [ $selectOptions ];
2311                 }
2312
2313                 list( $startOpts, $useIndex, $tailOpts, $ignoreIndex ) = $this->makeSelectOptions(
2314                         $selectOptions );
2315
2316                 if ( is_array( $srcTable ) ) {
2317                         $srcTable = implode( ',', array_map( [ &$this, 'tableName' ], $srcTable ) );
2318                 } else {
2319                         $srcTable = $this->tableName( $srcTable );
2320                 }
2321
2322                 $sql = "INSERT $insertOptions" .
2323                         " INTO $destTable (" . implode( ',', array_keys( $varMap ) ) . ')' .
2324                         " SELECT $startOpts " . implode( ',', $varMap ) .
2325                         " FROM $srcTable $useIndex $ignoreIndex ";
2326
2327                 if ( $conds != '*' ) {
2328                         if ( is_array( $conds ) ) {
2329                                 $conds = $this->makeList( $conds, self::LIST_AND );
2330                         }
2331                         $sql .= " WHERE $conds";
2332                 }
2333
2334                 $sql .= " $tailOpts";
2335
2336                 return $this->query( $sql, $fname );
2337         }
2338
2339         /**
2340          * Construct a LIMIT query with optional offset. This is used for query
2341          * pages. The SQL should be adjusted so that only the first $limit rows
2342          * are returned. If $offset is provided as well, then the first $offset
2343          * rows should be discarded, and the next $limit rows should be returned.
2344          * If the result of the query is not ordered, then the rows to be returned
2345          * are theoretically arbitrary.
2346          *
2347          * $sql is expected to be a SELECT, if that makes a difference.
2348          *
2349          * The version provided by default works in MySQL and SQLite. It will very
2350          * likely need to be overridden for most other DBMSes.
2351          *
2352          * @param string $sql SQL query we will append the limit too
2353          * @param int $limit The SQL limit
2354          * @param int|bool $offset The SQL offset (default false)
2355          * @throws DBUnexpectedError
2356          * @return string
2357          */
2358         public function limitResult( $sql, $limit, $offset = false ) {
2359                 if ( !is_numeric( $limit ) ) {
2360                         throw new DBUnexpectedError( $this,
2361                                 "Invalid non-numeric limit passed to limitResult()\n" );
2362                 }
2363
2364                 return "$sql LIMIT "
2365                 . ( ( is_numeric( $offset ) && $offset != 0 ) ? "{$offset}," : "" )
2366                 . "{$limit} ";
2367         }
2368
2369         public function unionSupportsOrderAndLimit() {
2370                 return true; // True for almost every DB supported
2371         }
2372
2373         public function unionQueries( $sqls, $all ) {
2374                 $glue = $all ? ') UNION ALL (' : ') UNION (';
2375
2376                 return '(' . implode( $glue, $sqls ) . ')';
2377         }
2378
2379         public function conditional( $cond, $trueVal, $falseVal ) {
2380                 if ( is_array( $cond ) ) {
2381                         $cond = $this->makeList( $cond, self::LIST_AND );
2382                 }
2383
2384                 return " (CASE WHEN $cond THEN $trueVal ELSE $falseVal END) ";
2385         }
2386
2387         public function strreplace( $orig, $old, $new ) {
2388                 return "REPLACE({$orig}, {$old}, {$new})";
2389         }
2390
2391         public function getServerUptime() {
2392                 return 0;
2393         }
2394
2395         public function wasDeadlock() {
2396                 return false;
2397         }
2398
2399         public function wasLockTimeout() {
2400                 return false;
2401         }
2402
2403         public function wasErrorReissuable() {
2404                 return false;
2405         }
2406
2407         public function wasReadOnlyError() {
2408                 return false;
2409         }
2410
2411         /**
2412          * Do not use this method outside of Database/DBError classes
2413          *
2414          * @param integer|string $errno
2415          * @return bool Whether the given query error was a connection drop
2416          */
2417         public function wasConnectionError( $errno ) {
2418                 return false;
2419         }
2420
2421         public function deadlockLoop() {
2422                 $args = func_get_args();
2423                 $function = array_shift( $args );
2424                 $tries = self::DEADLOCK_TRIES;
2425
2426                 $this->begin( __METHOD__ );
2427
2428                 $retVal = null;
2429                 /** @var Exception $e */
2430                 $e = null;
2431                 do {
2432                         try {
2433                                 $retVal = call_user_func_array( $function, $args );
2434                                 break;
2435                         } catch ( DBQueryError $e ) {
2436                                 if ( $this->wasDeadlock() ) {
2437                                         // Retry after a randomized delay
2438                                         usleep( mt_rand( self::DEADLOCK_DELAY_MIN, self::DEADLOCK_DELAY_MAX ) );
2439                                 } else {
2440                                         // Throw the error back up
2441                                         throw $e;
2442                                 }
2443                         }
2444                 } while ( --$tries > 0 );
2445
2446                 if ( $tries <= 0 ) {
2447                         // Too many deadlocks; give up
2448                         $this->rollback( __METHOD__ );
2449                         throw $e;
2450                 } else {
2451                         $this->commit( __METHOD__ );
2452
2453                         return $retVal;
2454                 }
2455         }
2456
2457         public function masterPosWait( DBMasterPos $pos, $timeout ) {
2458                 # Real waits are implemented in the subclass.
2459                 return 0;
2460         }
2461
2462         public function getReplicaPos() {
2463                 # Stub
2464                 return false;
2465         }
2466
2467         public function getMasterPos() {
2468                 # Stub
2469                 return false;
2470         }
2471
2472         public function serverIsReadOnly() {
2473                 return false;
2474         }
2475
2476         final public function onTransactionResolution( callable $callback, $fname = __METHOD__ ) {
2477                 if ( !$this->mTrxLevel ) {
2478                         throw new DBUnexpectedError( $this, "No transaction is active." );
2479                 }
2480                 $this->mTrxEndCallbacks[] = [ $callback, $fname ];
2481         }
2482
2483         final public function onTransactionIdle( callable $callback, $fname = __METHOD__ ) {
2484                 $this->mTrxIdleCallbacks[] = [ $callback, $fname ];
2485                 if ( !$this->mTrxLevel ) {
2486                         $this->runOnTransactionIdleCallbacks( self::TRIGGER_IDLE );
2487                 }
2488         }
2489
2490         final public function onTransactionPreCommitOrIdle( callable $callback, $fname = __METHOD__ ) {
2491                 if ( $this->mTrxLevel ) {
2492                         $this->mTrxPreCommitCallbacks[] = [ $callback, $fname ];
2493                 } else {
2494                         // If no transaction is active, then make one for this callback
2495                         $this->startAtomic( __METHOD__ );
2496                         try {
2497                                 call_user_func( $callback );
2498                                 $this->endAtomic( __METHOD__ );
2499                         } catch ( Exception $e ) {
2500                                 $this->rollback( __METHOD__, self::FLUSHING_INTERNAL );
2501                                 throw $e;
2502                         }
2503                 }
2504         }
2505
2506         final public function setTransactionListener( $name, callable $callback = null ) {
2507                 if ( $callback ) {
2508                         $this->mTrxRecurringCallbacks[$name] = $callback;
2509                 } else {
2510                         unset( $this->mTrxRecurringCallbacks[$name] );
2511                 }
2512         }
2513
2514         /**
2515          * Whether to disable running of post-COMMIT/ROLLBACK callbacks
2516          *
2517          * This method should not be used outside of Database/LoadBalancer
2518          *
2519          * @param bool $suppress
2520          * @since 1.28
2521          */
2522         final public function setTrxEndCallbackSuppression( $suppress ) {
2523                 $this->mTrxEndCallbacksSuppressed = $suppress;
2524         }
2525
2526         /**
2527          * Actually run and consume any "on transaction idle/resolution" callbacks.
2528          *
2529          * This method should not be used outside of Database/LoadBalancer
2530          *
2531          * @param integer $trigger IDatabase::TRIGGER_* constant
2532          * @since 1.20
2533          * @throws Exception
2534          */
2535         public function runOnTransactionIdleCallbacks( $trigger ) {
2536                 if ( $this->mTrxEndCallbacksSuppressed ) {
2537                         return;
2538                 }
2539
2540                 $autoTrx = $this->getFlag( self::DBO_TRX ); // automatic begin() enabled?
2541                 /** @var Exception $e */
2542                 $e = null; // first exception
2543                 do { // callbacks may add callbacks :)
2544                         $callbacks = array_merge(
2545                                 $this->mTrxIdleCallbacks,
2546                                 $this->mTrxEndCallbacks // include "transaction resolution" callbacks
2547                         );
2548                         $this->mTrxIdleCallbacks = []; // consumed (and recursion guard)
2549                         $this->mTrxEndCallbacks = []; // consumed (recursion guard)
2550                         foreach ( $callbacks as $callback ) {
2551                                 try {
2552                                         list( $phpCallback ) = $callback;
2553                                         $this->clearFlag( self::DBO_TRX ); // make each query its own transaction
2554                                         call_user_func_array( $phpCallback, [ $trigger ] );
2555                                         if ( $autoTrx ) {
2556                                                 $this->setFlag( self::DBO_TRX ); // restore automatic begin()
2557                                         } else {
2558                                                 $this->clearFlag( self::DBO_TRX ); // restore auto-commit
2559                                         }
2560                                 } catch ( Exception $ex ) {
2561                                         call_user_func( $this->errorLogger, $ex );
2562                                         $e = $e ?: $ex;
2563                                         // Some callbacks may use startAtomic/endAtomic, so make sure
2564                                         // their transactions are ended so other callbacks don't fail
2565                                         if ( $this->trxLevel() ) {
2566                                                 $this->rollback( __METHOD__, self::FLUSHING_INTERNAL );
2567                                         }
2568                                 }
2569                         }
2570                 } while ( count( $this->mTrxIdleCallbacks ) );
2571
2572                 if ( $e instanceof Exception ) {
2573                         throw $e; // re-throw any first exception
2574                 }
2575         }
2576
2577         /**
2578          * Actually run and consume any "on transaction pre-commit" callbacks.
2579          *
2580          * This method should not be used outside of Database/LoadBalancer
2581          *
2582          * @since 1.22
2583          * @throws Exception
2584          */
2585         public function runOnTransactionPreCommitCallbacks() {
2586                 $e = null; // first exception
2587                 do { // callbacks may add callbacks :)
2588                         $callbacks = $this->mTrxPreCommitCallbacks;
2589                         $this->mTrxPreCommitCallbacks = []; // consumed (and recursion guard)
2590                         foreach ( $callbacks as $callback ) {
2591                                 try {
2592                                         list( $phpCallback ) = $callback;
2593                                         call_user_func( $phpCallback );
2594                                 } catch ( Exception $ex ) {
2595                                         call_user_func( $this->errorLogger, $ex );
2596                                         $e = $e ?: $ex;
2597                                 }
2598                         }
2599                 } while ( count( $this->mTrxPreCommitCallbacks ) );
2600
2601                 if ( $e instanceof Exception ) {
2602                         throw $e; // re-throw any first exception
2603                 }
2604         }
2605
2606         /**
2607          * Actually run any "transaction listener" callbacks.
2608          *
2609          * This method should not be used outside of Database/LoadBalancer
2610          *
2611          * @param integer $trigger IDatabase::TRIGGER_* constant
2612          * @throws Exception
2613          * @since 1.20
2614          */
2615         public function runTransactionListenerCallbacks( $trigger ) {
2616                 if ( $this->mTrxEndCallbacksSuppressed ) {
2617                         return;
2618                 }
2619
2620                 /** @var Exception $e */
2621                 $e = null; // first exception
2622
2623                 foreach ( $this->mTrxRecurringCallbacks as $phpCallback ) {
2624                         try {
2625                                 $phpCallback( $trigger, $this );
2626                         } catch ( Exception $ex ) {
2627                                 call_user_func( $this->errorLogger, $ex );
2628                                 $e = $e ?: $ex;
2629                         }
2630                 }
2631
2632                 if ( $e instanceof Exception ) {
2633                         throw $e; // re-throw any first exception
2634                 }
2635         }
2636
2637         final public function startAtomic( $fname = __METHOD__ ) {
2638                 if ( !$this->mTrxLevel ) {
2639                         $this->begin( $fname, self::TRANSACTION_INTERNAL );
2640                         // If DBO_TRX is set, a series of startAtomic/endAtomic pairs will result
2641                         // in all changes being in one transaction to keep requests transactional.
2642                         if ( !$this->getFlag( self::DBO_TRX ) ) {
2643                                 $this->mTrxAutomaticAtomic = true;
2644                         }
2645                 }
2646
2647                 $this->mTrxAtomicLevels[] = $fname;
2648         }
2649
2650         final public function endAtomic( $fname = __METHOD__ ) {
2651                 if ( !$this->mTrxLevel ) {
2652                         throw new DBUnexpectedError( $this, "No atomic transaction is open (got $fname)." );
2653                 }
2654                 if ( !$this->mTrxAtomicLevels ||
2655                         array_pop( $this->mTrxAtomicLevels ) !== $fname
2656                 ) {
2657                         throw new DBUnexpectedError( $this, "Invalid atomic section ended (got $fname)." );
2658                 }
2659
2660                 if ( !$this->mTrxAtomicLevels && $this->mTrxAutomaticAtomic ) {
2661                         $this->commit( $fname, self::FLUSHING_INTERNAL );
2662                 }
2663         }
2664
2665         final public function doAtomicSection( $fname, callable $callback ) {
2666                 $this->startAtomic( $fname );
2667                 try {
2668                         $res = call_user_func_array( $callback, [ $this, $fname ] );
2669                 } catch ( Exception $e ) {
2670                         $this->rollback( $fname, self::FLUSHING_INTERNAL );
2671                         throw $e;
2672                 }
2673                 $this->endAtomic( $fname );
2674
2675                 return $res;
2676         }
2677
2678         final public function begin( $fname = __METHOD__, $mode = self::TRANSACTION_EXPLICIT ) {
2679                 // Protect against mismatched atomic section, transaction nesting, and snapshot loss
2680                 if ( $this->mTrxLevel ) {
2681                         if ( $this->mTrxAtomicLevels ) {
2682                                 $levels = implode( ', ', $this->mTrxAtomicLevels );
2683                                 $msg = "$fname: Got explicit BEGIN while atomic section(s) $levels are open.";
2684                                 throw new DBUnexpectedError( $this, $msg );
2685                         } elseif ( !$this->mTrxAutomatic ) {
2686                                 $msg = "$fname: Explicit transaction already active (from {$this->mTrxFname}).";
2687                                 throw new DBUnexpectedError( $this, $msg );
2688                         } else {
2689                                 // @TODO: make this an exception at some point
2690                                 $msg = "$fname: Implicit transaction already active (from {$this->mTrxFname}).";
2691                                 $this->queryLogger->error( $msg );
2692                                 return; // join the main transaction set
2693                         }
2694                 } elseif ( $this->getFlag( self::DBO_TRX ) && $mode !== self::TRANSACTION_INTERNAL ) {
2695                         // @TODO: make this an exception at some point
2696                         $msg = "$fname: Implicit transaction expected (DBO_TRX set).";
2697                         $this->queryLogger->error( $msg );
2698                         return; // let any writes be in the main transaction
2699                 }
2700
2701                 // Avoid fatals if close() was called
2702                 $this->assertOpen();
2703
2704                 $this->doBegin( $fname );
2705                 $this->mTrxTimestamp = microtime( true );
2706                 $this->mTrxFname = $fname;
2707                 $this->mTrxDoneWrites = false;
2708                 $this->mTrxAutomaticAtomic = false;
2709                 $this->mTrxAtomicLevels = [];
2710                 $this->mTrxShortId = sprintf( '%06x', mt_rand( 0, 0xffffff ) );
2711                 $this->mTrxWriteDuration = 0.0;
2712                 $this->mTrxWriteQueryCount = 0;
2713                 $this->mTrxWriteAdjDuration = 0.0;
2714                 $this->mTrxWriteAdjQueryCount = 0;
2715                 $this->mTrxWriteCallers = [];
2716                 // First SELECT after BEGIN will establish the snapshot in REPEATABLE-READ.
2717                 // Get an estimate of the replica DB lag before then, treating estimate staleness
2718                 // as lag itself just to be safe
2719                 $status = $this->getApproximateLagStatus();
2720                 $this->mTrxReplicaLag = $status['lag'] + ( microtime( true ) - $status['since'] );
2721                 // T147697: make explicitTrxActive() return true until begin() finishes. This way, no
2722                 // caller will think its OK to muck around with the transaction just because startAtomic()
2723                 // has not yet completed (e.g. setting mTrxAtomicLevels).
2724                 $this->mTrxAutomatic = ( $mode === self::TRANSACTION_INTERNAL );
2725         }
2726
2727         /**
2728          * Issues the BEGIN command to the database server.
2729          *
2730          * @see Database::begin()
2731          * @param string $fname
2732          */
2733         protected function doBegin( $fname ) {
2734                 $this->query( 'BEGIN', $fname );
2735                 $this->mTrxLevel = 1;
2736         }
2737
2738         final public function commit( $fname = __METHOD__, $flush = '' ) {
2739                 if ( $this->mTrxLevel && $this->mTrxAtomicLevels ) {
2740                         // There are still atomic sections open. This cannot be ignored
2741                         $levels = implode( ', ', $this->mTrxAtomicLevels );
2742                         throw new DBUnexpectedError(
2743                                 $this,
2744                                 "$fname: Got COMMIT while atomic sections $levels are still open."
2745                         );
2746                 }
2747
2748                 if ( $flush === self::FLUSHING_INTERNAL || $flush === self::FLUSHING_ALL_PEERS ) {
2749                         if ( !$this->mTrxLevel ) {
2750                                 return; // nothing to do
2751                         } elseif ( !$this->mTrxAutomatic ) {
2752                                 throw new DBUnexpectedError(
2753                                         $this,
2754                                         "$fname: Flushing an explicit transaction, getting out of sync."
2755                                 );
2756                         }
2757                 } else {
2758                         if ( !$this->mTrxLevel ) {
2759                                 $this->queryLogger->error(
2760                                         "$fname: No transaction to commit, something got out of sync." );
2761                                 return; // nothing to do
2762                         } elseif ( $this->mTrxAutomatic ) {
2763                                 // @TODO: make this an exception at some point
2764                                 $msg = "$fname: Explicit commit of implicit transaction.";
2765                                 $this->queryLogger->error( $msg );
2766                                 return; // wait for the main transaction set commit round
2767                         }
2768                 }
2769
2770                 // Avoid fatals if close() was called
2771                 $this->assertOpen();
2772
2773                 $this->runOnTransactionPreCommitCallbacks();
2774                 $writeTime = $this->pendingWriteQueryDuration( self::ESTIMATE_DB_APPLY );
2775                 $this->doCommit( $fname );
2776                 if ( $this->mTrxDoneWrites ) {
2777                         $this->mLastWriteTime = microtime( true );
2778                         $this->trxProfiler->transactionWritingOut(
2779                                 $this->mServer, $this->mDBname, $this->mTrxShortId, $writeTime );
2780                 }
2781
2782                 $this->runOnTransactionIdleCallbacks( self::TRIGGER_COMMIT );
2783                 $this->runTransactionListenerCallbacks( self::TRIGGER_COMMIT );
2784         }
2785
2786         /**
2787          * Issues the COMMIT command to the database server.
2788          *
2789          * @see Database::commit()
2790          * @param string $fname
2791          */
2792         protected function doCommit( $fname ) {
2793                 if ( $this->mTrxLevel ) {
2794                         $this->query( 'COMMIT', $fname );
2795                         $this->mTrxLevel = 0;
2796                 }
2797         }
2798
2799         final public function rollback( $fname = __METHOD__, $flush = '' ) {
2800                 if ( $flush === self::FLUSHING_INTERNAL || $flush === self::FLUSHING_ALL_PEERS ) {
2801                         if ( !$this->mTrxLevel ) {
2802                                 return; // nothing to do
2803                         }
2804                 } else {
2805                         if ( !$this->mTrxLevel ) {
2806                                 $this->queryLogger->error(
2807                                         "$fname: No transaction to rollback, something got out of sync." );
2808                                 return; // nothing to do
2809                         } elseif ( $this->getFlag( self::DBO_TRX ) ) {
2810                                 throw new DBUnexpectedError(
2811                                         $this,
2812                                         "$fname: Expected mass rollback of all peer databases (DBO_TRX set)."
2813                                 );
2814                         }
2815                 }
2816
2817                 // Avoid fatals if close() was called
2818                 $this->assertOpen();
2819
2820                 $this->doRollback( $fname );
2821                 $this->mTrxAtomicLevels = [];
2822                 if ( $this->mTrxDoneWrites ) {
2823                         $this->trxProfiler->transactionWritingOut(
2824                                 $this->mServer, $this->mDBname, $this->mTrxShortId );
2825                 }
2826
2827                 $this->mTrxIdleCallbacks = []; // clear
2828                 $this->mTrxPreCommitCallbacks = []; // clear
2829                 $this->runOnTransactionIdleCallbacks( self::TRIGGER_ROLLBACK );
2830                 $this->runTransactionListenerCallbacks( self::TRIGGER_ROLLBACK );
2831         }
2832
2833         /**
2834          * Issues the ROLLBACK command to the database server.
2835          *
2836          * @see Database::rollback()
2837          * @param string $fname
2838          */
2839         protected function doRollback( $fname ) {
2840                 if ( $this->mTrxLevel ) {
2841                         # Disconnects cause rollback anyway, so ignore those errors
2842                         $ignoreErrors = true;
2843                         $this->query( 'ROLLBACK', $fname, $ignoreErrors );
2844                         $this->mTrxLevel = 0;
2845                 }
2846         }
2847
2848         public function flushSnapshot( $fname = __METHOD__ ) {
2849                 if ( $this->writesOrCallbacksPending() || $this->explicitTrxActive() ) {
2850                         // This only flushes transactions to clear snapshots, not to write data
2851                         $fnames = implode( ', ', $this->pendingWriteAndCallbackCallers() );
2852                         throw new DBUnexpectedError(
2853                                 $this,
2854                                 "$fname: Cannot flush snapshot because writes are pending ($fnames)."
2855                         );
2856                 }
2857
2858                 $this->commit( $fname, self::FLUSHING_INTERNAL );
2859         }
2860
2861         public function explicitTrxActive() {
2862                 return $this->mTrxLevel && ( $this->mTrxAtomicLevels || !$this->mTrxAutomatic );
2863         }
2864
2865         /**
2866          * Creates a new table with structure copied from existing table
2867          * Note that unlike most database abstraction functions, this function does not
2868          * automatically append database prefix, because it works at a lower
2869          * abstraction level.
2870          * The table names passed to this function shall not be quoted (this
2871          * function calls addIdentifierQuotes when needed).
2872          *
2873          * @param string $oldName Name of table whose structure should be copied
2874          * @param string $newName Name of table to be created
2875          * @param bool $temporary Whether the new table should be temporary
2876          * @param string $fname Calling function name
2877          * @throws RuntimeException
2878          * @return bool True if operation was successful
2879          */
2880         public function duplicateTableStructure( $oldName, $newName, $temporary = false,
2881                 $fname = __METHOD__
2882         ) {
2883                 throw new RuntimeException( __METHOD__ . ' is not implemented in descendant class' );
2884         }
2885
2886         public function listTables( $prefix = null, $fname = __METHOD__ ) {
2887                 throw new RuntimeException( __METHOD__ . ' is not implemented in descendant class' );
2888         }
2889
2890         public function listViews( $prefix = null, $fname = __METHOD__ ) {
2891                 throw new RuntimeException( __METHOD__ . ' is not implemented in descendant class' );
2892         }
2893
2894         public function timestamp( $ts = 0 ) {
2895                 $t = new ConvertibleTimestamp( $ts );
2896                 // Let errors bubble up to avoid putting garbage in the DB
2897                 return $t->getTimestamp( TS_MW );
2898         }
2899
2900         public function timestampOrNull( $ts = null ) {
2901                 if ( is_null( $ts ) ) {
2902                         return null;
2903                 } else {
2904                         return $this->timestamp( $ts );
2905                 }
2906         }
2907
2908         /**
2909          * Take the result from a query, and wrap it in a ResultWrapper if
2910          * necessary. Boolean values are passed through as is, to indicate success
2911          * of write queries or failure.
2912          *
2913          * Once upon a time, Database::query() returned a bare MySQL result
2914          * resource, and it was necessary to call this function to convert it to
2915          * a wrapper. Nowadays, raw database objects are never exposed to external
2916          * callers, so this is unnecessary in external code.
2917          *
2918          * @param bool|ResultWrapper|resource|object $result
2919          * @return bool|ResultWrapper
2920          */
2921         protected function resultObject( $result ) {
2922                 if ( !$result ) {
2923                         return false;
2924                 } elseif ( $result instanceof ResultWrapper ) {
2925                         return $result;
2926                 } elseif ( $result === true ) {
2927                         // Successful write query
2928                         return $result;
2929                 } else {
2930                         return new ResultWrapper( $this, $result );
2931                 }
2932         }
2933
2934         public function ping( &$rtt = null ) {
2935                 // Avoid hitting the server if it was hit recently
2936                 if ( $this->isOpen() && ( microtime( true ) - $this->lastPing ) < self::PING_TTL ) {
2937                         if ( !func_num_args() || $this->mRTTEstimate > 0 ) {
2938                                 $rtt = $this->mRTTEstimate;
2939                                 return true; // don't care about $rtt
2940                         }
2941                 }
2942
2943                 // This will reconnect if possible or return false if not
2944                 $this->clearFlag( self::DBO_TRX, self::REMEMBER_PRIOR );
2945                 $ok = ( $this->query( self::PING_QUERY, __METHOD__, true ) !== false );
2946                 $this->restoreFlags( self::RESTORE_PRIOR );
2947
2948                 if ( $ok ) {
2949                         $rtt = $this->mRTTEstimate;
2950                 }
2951
2952                 return $ok;
2953         }
2954
2955         /**
2956          * @return bool
2957          */
2958         protected function reconnect() {
2959                 $this->closeConnection();
2960                 $this->mOpened = false;
2961                 $this->mConn = false;
2962                 try {
2963                         $this->open( $this->mServer, $this->mUser, $this->mPassword, $this->mDBname );
2964                         $this->lastPing = microtime( true );
2965                         $ok = true;
2966                 } catch ( DBConnectionError $e ) {
2967                         $ok = false;
2968                 }
2969
2970                 return $ok;
2971         }
2972
2973         public function getSessionLagStatus() {
2974                 return $this->getTransactionLagStatus() ?: $this->getApproximateLagStatus();
2975         }
2976
2977         /**
2978          * Get the replica DB lag when the current transaction started
2979          *
2980          * This is useful when transactions might use snapshot isolation
2981          * (e.g. REPEATABLE-READ in innodb), so the "real" lag of that data
2982          * is this lag plus transaction duration. If they don't, it is still
2983          * safe to be pessimistic. This returns null if there is no transaction.
2984          *
2985          * @return array|null ('lag': seconds or false on error, 'since': UNIX timestamp of BEGIN)
2986          * @since 1.27
2987          */
2988         protected function getTransactionLagStatus() {
2989                 return $this->mTrxLevel
2990                         ? [ 'lag' => $this->mTrxReplicaLag, 'since' => $this->trxTimestamp() ]
2991                         : null;
2992         }
2993
2994         /**
2995          * Get a replica DB lag estimate for this server
2996          *
2997          * @return array ('lag': seconds or false on error, 'since': UNIX timestamp of estimate)
2998          * @since 1.27
2999          */
3000         protected function getApproximateLagStatus() {
3001                 return [
3002                         'lag'   => $this->getLBInfo( 'replica' ) ? $this->getLag() : 0,
3003                         'since' => microtime( true )
3004                 ];
3005         }
3006
3007         /**
3008          * Merge the result of getSessionLagStatus() for several DBs
3009          * using the most pessimistic values to estimate the lag of
3010          * any data derived from them in combination
3011          *
3012          * This is information is useful for caching modules
3013          *
3014          * @see WANObjectCache::set()
3015          * @see WANObjectCache::getWithSetCallback()
3016          *
3017          * @param IDatabase $db1
3018          * @param IDatabase ...
3019          * @return array Map of values:
3020          *   - lag: highest lag of any of the DBs or false on error (e.g. replication stopped)
3021          *   - since: oldest UNIX timestamp of any of the DB lag estimates
3022          *   - pending: whether any of the DBs have uncommitted changes
3023          * @since 1.27
3024          */
3025         public static function getCacheSetOptions( IDatabase $db1 ) {
3026                 $res = [ 'lag' => 0, 'since' => INF, 'pending' => false ];
3027                 foreach ( func_get_args() as $db ) {
3028                         /** @var IDatabase $db */
3029                         $status = $db->getSessionLagStatus();
3030                         if ( $status['lag'] === false ) {
3031                                 $res['lag'] = false;
3032                         } elseif ( $res['lag'] !== false ) {
3033                                 $res['lag'] = max( $res['lag'], $status['lag'] );
3034                         }
3035                         $res['since'] = min( $res['since'], $status['since'] );
3036                         $res['pending'] = $res['pending'] ?: $db->writesPending();
3037                 }
3038
3039                 return $res;
3040         }
3041
3042         public function getLag() {
3043                 return 0;
3044         }
3045
3046         public function maxListLen() {
3047                 return 0;
3048         }
3049
3050         public function encodeBlob( $b ) {
3051                 return $b;
3052         }
3053
3054         public function decodeBlob( $b ) {
3055                 if ( $b instanceof Blob ) {
3056                         $b = $b->fetch();
3057                 }
3058                 return $b;
3059         }
3060
3061         public function setSessionOptions( array $options ) {
3062         }
3063
3064         public function sourceFile(
3065                 $filename,
3066                 callable $lineCallback = null,
3067                 callable $resultCallback = null,
3068                 $fname = false,
3069                 callable $inputCallback = null
3070         ) {
3071                 MediaWiki\suppressWarnings();
3072                 $fp = fopen( $filename, 'r' );
3073                 MediaWiki\restoreWarnings();
3074
3075                 if ( false === $fp ) {
3076                         throw new RuntimeException( "Could not open \"{$filename}\".\n" );
3077                 }
3078
3079                 if ( !$fname ) {
3080                         $fname = __METHOD__ . "( $filename )";
3081                 }
3082
3083                 try {
3084                         $error = $this->sourceStream(
3085                                 $fp, $lineCallback, $resultCallback, $fname, $inputCallback );
3086                 } catch ( Exception $e ) {
3087                         fclose( $fp );
3088                         throw $e;
3089                 }
3090
3091                 fclose( $fp );
3092
3093                 return $error;
3094         }
3095
3096         public function setSchemaVars( $vars ) {
3097                 $this->mSchemaVars = $vars;
3098         }
3099
3100         public function sourceStream(
3101                 $fp,
3102                 callable $lineCallback = null,
3103                 callable $resultCallback = null,
3104                 $fname = __METHOD__,
3105                 callable $inputCallback = null
3106         ) {
3107                 $cmd = '';
3108
3109                 while ( !feof( $fp ) ) {
3110                         if ( $lineCallback ) {
3111                                 call_user_func( $lineCallback );
3112                         }
3113
3114                         $line = trim( fgets( $fp ) );
3115
3116                         if ( $line == '' ) {
3117                                 continue;
3118                         }
3119
3120                         if ( '-' == $line[0] && '-' == $line[1] ) {
3121                                 continue;
3122                         }
3123
3124                         if ( $cmd != '' ) {
3125                                 $cmd .= ' ';
3126                         }
3127
3128                         $done = $this->streamStatementEnd( $cmd, $line );
3129
3130                         $cmd .= "$line\n";
3131
3132                         if ( $done || feof( $fp ) ) {
3133                                 $cmd = $this->replaceVars( $cmd );
3134
3135                                 if ( !$inputCallback || call_user_func( $inputCallback, $cmd ) ) {
3136                                         $res = $this->query( $cmd, $fname );
3137
3138                                         if ( $resultCallback ) {
3139                                                 call_user_func( $resultCallback, $res, $this );
3140                                         }
3141
3142                                         if ( false === $res ) {
3143                                                 $err = $this->lastError();
3144
3145                                                 return "Query \"{$cmd}\" failed with error code \"$err\".\n";
3146                                         }
3147                                 }
3148                                 $cmd = '';
3149                         }
3150                 }
3151
3152                 return true;
3153         }
3154
3155         /**
3156          * Called by sourceStream() to check if we've reached a statement end
3157          *
3158          * @param string &$sql SQL assembled so far
3159          * @param string &$newLine New line about to be added to $sql
3160          * @return bool Whether $newLine contains end of the statement
3161          */
3162         public function streamStatementEnd( &$sql, &$newLine ) {
3163                 if ( $this->delimiter ) {
3164                         $prev = $newLine;
3165                         $newLine = preg_replace(
3166                                 '/' . preg_quote( $this->delimiter, '/' ) . '$/', '', $newLine );
3167                         if ( $newLine != $prev ) {
3168                                 return true;
3169                         }
3170                 }
3171
3172                 return false;
3173         }
3174
3175         /**
3176          * Database independent variable replacement. Replaces a set of variables
3177          * in an SQL statement with their contents as given by $this->getSchemaVars().
3178          *
3179          * Supports '{$var}' `{$var}` and / *$var* / (without the spaces) style variables.
3180          *
3181          * - '{$var}' should be used for text and is passed through the database's
3182          *   addQuotes method.
3183          * - `{$var}` should be used for identifiers (e.g. table and database names).
3184          *   It is passed through the database's addIdentifierQuotes method which
3185          *   can be overridden if the database uses something other than backticks.
3186          * - / *_* / or / *$wgDBprefix* / passes the name that follows through the
3187          *   database's tableName method.
3188          * - / *i* / passes the name that follows through the database's indexName method.
3189          * - In all other cases, / *$var* / is left unencoded. Except for table options,
3190          *   its use should be avoided. In 1.24 and older, string encoding was applied.
3191          *
3192          * @param string $ins SQL statement to replace variables in
3193          * @return string The new SQL statement with variables replaced
3194          */
3195         protected function replaceVars( $ins ) {
3196                 $vars = $this->getSchemaVars();
3197                 return preg_replace_callback(
3198                         '!
3199                                 /\* (\$wgDBprefix|[_i]) \*/ (\w*) | # 1-2. tableName, indexName
3200                                 \'\{\$ (\w+) }\'                  | # 3. addQuotes
3201                                 `\{\$ (\w+) }`                    | # 4. addIdentifierQuotes
3202                                 /\*\$ (\w+) \*/                     # 5. leave unencoded
3203                         !x',
3204                         function ( $m ) use ( $vars ) {
3205                                 // Note: Because of <https://bugs.php.net/bug.php?id=51881>,
3206                                 // check for both nonexistent keys *and* the empty string.
3207                                 if ( isset( $m[1] ) && $m[1] !== '' ) {
3208                                         if ( $m[1] === 'i' ) {
3209                                                 return $this->indexName( $m[2] );
3210                                         } else {
3211                                                 return $this->tableName( $m[2] );
3212                                         }
3213                                 } elseif ( isset( $m[3] ) && $m[3] !== '' && array_key_exists( $m[3], $vars ) ) {
3214                                         return $this->addQuotes( $vars[$m[3]] );
3215                                 } elseif ( isset( $m[4] ) && $m[4] !== '' && array_key_exists( $m[4], $vars ) ) {
3216                                         return $this->addIdentifierQuotes( $vars[$m[4]] );
3217                                 } elseif ( isset( $m[5] ) && $m[5] !== '' && array_key_exists( $m[5], $vars ) ) {
3218                                         return $vars[$m[5]];
3219                                 } else {
3220                                         return $m[0];
3221                                 }
3222                         },
3223                         $ins
3224                 );
3225         }
3226
3227         /**
3228          * Get schema variables. If none have been set via setSchemaVars(), then
3229          * use some defaults from the current object.
3230          *
3231          * @return array
3232          */
3233         protected function getSchemaVars() {
3234                 if ( $this->mSchemaVars ) {
3235                         return $this->mSchemaVars;
3236                 } else {
3237                         return $this->getDefaultSchemaVars();
3238                 }
3239         }
3240
3241         /**
3242          * Get schema variables to use if none have been set via setSchemaVars().
3243          *
3244          * Override this in derived classes to provide variables for tables.sql
3245          * and SQL patch files.
3246          *
3247          * @return array
3248          */
3249         protected function getDefaultSchemaVars() {
3250                 return [];
3251         }
3252
3253         public function lockIsFree( $lockName, $method ) {
3254                 return true;
3255         }
3256
3257         public function lock( $lockName, $method, $timeout = 5 ) {
3258                 $this->mNamedLocksHeld[$lockName] = 1;
3259
3260                 return true;
3261         }
3262
3263         public function unlock( $lockName, $method ) {
3264                 unset( $this->mNamedLocksHeld[$lockName] );
3265
3266                 return true;
3267         }
3268
3269         public function getScopedLockAndFlush( $lockKey, $fname, $timeout ) {
3270                 if ( $this->writesOrCallbacksPending() ) {
3271                         // This only flushes transactions to clear snapshots, not to write data
3272                         $fnames = implode( ', ', $this->pendingWriteAndCallbackCallers() );
3273                         throw new DBUnexpectedError(
3274                                 $this,
3275                                 "$fname: Cannot flush pre-lock snapshot because writes are pending ($fnames)."
3276                         );
3277                 }
3278
3279                 if ( !$this->lock( $lockKey, $fname, $timeout ) ) {
3280                         return null;
3281                 }
3282
3283                 $unlocker = new ScopedCallback( function () use ( $lockKey, $fname ) {
3284                         if ( $this->trxLevel() ) {
3285                                 // There is a good chance an exception was thrown, causing any early return
3286                                 // from the caller. Let any error handler get a chance to issue rollback().
3287                                 // If there isn't one, let the error bubble up and trigger server-side rollback.
3288                                 $this->onTransactionResolution(
3289                                         function () use ( $lockKey, $fname ) {
3290                                                 $this->unlock( $lockKey, $fname );
3291                                         },
3292                                         $fname
3293                                 );
3294                         } else {
3295                                 $this->unlock( $lockKey, $fname );
3296                         }
3297                 } );
3298
3299                 $this->commit( $fname, self::FLUSHING_INTERNAL );
3300
3301                 return $unlocker;
3302         }
3303
3304         public function namedLocksEnqueue() {
3305                 return false;
3306         }
3307
3308         /**
3309          * Lock specific tables
3310          *
3311          * @param array $read Array of tables to lock for read access
3312          * @param array $write Array of tables to lock for write access
3313          * @param string $method Name of caller
3314          * @param bool $lowPriority Whether to indicate writes to be LOW PRIORITY
3315          * @return bool
3316          */
3317         public function lockTables( $read, $write, $method, $lowPriority = true ) {
3318                 return true;
3319         }
3320
3321         /**
3322          * Unlock specific tables
3323          *
3324          * @param string $method The caller
3325          * @return bool
3326          */
3327         public function unlockTables( $method ) {
3328                 return true;
3329         }
3330
3331         /**
3332          * Delete a table
3333          * @param string $tableName
3334          * @param string $fName
3335          * @return bool|ResultWrapper
3336          * @since 1.18
3337          */
3338         public function dropTable( $tableName, $fName = __METHOD__ ) {
3339                 if ( !$this->tableExists( $tableName, $fName ) ) {
3340                         return false;
3341                 }
3342                 $sql = "DROP TABLE " . $this->tableName( $tableName ) . " CASCADE";
3343
3344                 return $this->query( $sql, $fName );
3345         }
3346
3347         public function getInfinity() {
3348                 return 'infinity';
3349         }
3350
3351         public function encodeExpiry( $expiry ) {
3352                 return ( $expiry == '' || $expiry == 'infinity' || $expiry == $this->getInfinity() )
3353                         ? $this->getInfinity()
3354                         : $this->timestamp( $expiry );
3355         }
3356
3357         public function decodeExpiry( $expiry, $format = TS_MW ) {
3358                 if ( $expiry == '' || $expiry == 'infinity' || $expiry == $this->getInfinity() ) {
3359                         return 'infinity';
3360                 }
3361
3362                 return ConvertibleTimestamp::convert( $format, $expiry );
3363         }
3364
3365         public function setBigSelects( $value = true ) {
3366                 // no-op
3367         }
3368
3369         public function isReadOnly() {
3370                 return ( $this->getReadOnlyReason() !== false );
3371         }
3372
3373         /**
3374          * @return string|bool Reason this DB is read-only or false if it is not
3375          */
3376         protected function getReadOnlyReason() {
3377                 $reason = $this->getLBInfo( 'readOnlyReason' );
3378
3379                 return is_string( $reason ) ? $reason : false;
3380         }
3381
3382         public function setTableAliases( array $aliases ) {
3383                 $this->tableAliases = $aliases;
3384         }
3385
3386         /**
3387          * @return bool Whether a DB user is required to access the DB
3388          * @since 1.28
3389          */
3390         protected function requiresDatabaseUser() {
3391                 return true;
3392         }
3393
3394         /**
3395          * Get the underlying binding handle, mConn
3396          *
3397          * Makes sure that mConn is set (disconnects and ping() failure can unset it).
3398          * This catches broken callers than catch and ignore disconnection exceptions.
3399          * Unlike checking isOpen(), this is safe to call inside of open().
3400          *
3401          * @return resource|object
3402          * @throws DBUnexpectedError
3403          * @since 1.26
3404          */
3405         protected function getBindingHandle() {
3406                 if ( !$this->mConn ) {
3407                         throw new DBUnexpectedError(
3408                                 $this,
3409                                 'DB connection was already closed or the connection dropped.'
3410                         );
3411                 }
3412
3413                 return $this->mConn;
3414         }
3415
3416         /**
3417          * @since 1.19
3418          * @return string
3419          */
3420         public function __toString() {
3421                 return (string)$this->mConn;
3422         }
3423
3424         /**
3425          * Make sure that copies do not share the same client binding handle
3426          * @throws DBConnectionError
3427          */
3428         public function __clone() {
3429                 $this->connLogger->warning(
3430                         "Cloning " . get_class( $this ) . " is not recomended; forking connection:\n" .
3431                         ( new RuntimeException() )->getTraceAsString()
3432                 );
3433
3434                 if ( $this->isOpen() ) {
3435                         // Open a new connection resource without messing with the old one
3436                         $this->mOpened = false;
3437                         $this->mConn = false;
3438                         $this->mTrxEndCallbacks = []; // don't copy
3439                         $this->handleSessionLoss(); // no trx or locks anymore
3440                         $this->open( $this->mServer, $this->mUser, $this->mPassword, $this->mDBname );
3441                         $this->lastPing = microtime( true );
3442                 }
3443         }
3444
3445         /**
3446          * Called by serialize. Throw an exception when DB connection is serialized.
3447          * This causes problems on some database engines because the connection is
3448          * not restored on unserialize.
3449          */
3450         public function __sleep() {
3451                 throw new RuntimeException( 'Database serialization may cause problems, since ' .
3452                         'the connection is not restored on wakeup.' );
3453         }
3454
3455         /**
3456          * Run a few simple sanity checks and close dangling connections
3457          */
3458         public function __destruct() {
3459                 if ( $this->mTrxLevel && $this->mTrxDoneWrites ) {
3460                         trigger_error( "Uncommitted DB writes (transaction from {$this->mTrxFname})." );
3461                 }
3462
3463                 $danglingWriters = $this->pendingWriteAndCallbackCallers();
3464                 if ( $danglingWriters ) {
3465                         $fnames = implode( ', ', $danglingWriters );
3466                         trigger_error( "DB transaction writes or callbacks still pending ($fnames)." );
3467                 }
3468
3469                 if ( $this->mConn ) {
3470                         // Avoid connection leaks for sanity. Normally, resources close at script completion.
3471                         // The connection might already be closed in zend/hhvm by now, so suppress warnings.
3472                         \MediaWiki\suppressWarnings();
3473                         $this->closeConnection();
3474                         \MediaWiki\restoreWarnings();
3475                         $this->mConn = false;
3476                         $this->mOpened = false;
3477                 }
3478         }
3479 }
3480
3481 class_alias( 'Database', 'DatabaseBase' );