includes/libs/rdbms/database/Database.php

   1 <?php
   2 /**
   3  * @defgroup Database Database
   4  *
   5  * This file deals with database interface functions
   6  * and query specifics/optimisations.
   7  *
   8  * This program is free software; you can redistribute it and/or modify
   9  * it under the terms of the GNU General Public License as published by
  10  * the Free Software Foundation; either version 2 of the License, or
  11  * (at your option) any later version.
  12  *
  13  * This program is distributed in the hope that it will be useful,
  14  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  15  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
  16  * GNU General Public License for more details.
  17  *
  18  * You should have received a copy of the GNU General Public License along
  19  * with this program; if not, write to the Free Software Foundation, Inc.,
  20  * 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
  21  * http://www.gnu.org/copyleft/gpl.html
  22  *
  23  * @file
  24  * @ingroup Database
  25  */
  26 use Psr\Log\LoggerAwareInterface;
  27 use Psr\Log\LoggerInterface;
  28 use Wikimedia\ScopedCallback;
  29
  30 /**
  31  * Relational database abstraction object
  32  *
  33  * @ingroup Database
  34  * @since 1.28
  35  */
  36 abstract class Database implements IDatabase, IMaintainableDatabase, LoggerAwareInterface {
  37         /** Number of times to re-try an operation in case of deadlock */
  38         const DEADLOCK_TRIES = 4;
  39         /** Minimum time to wait before retry, in microseconds */
  40         const DEADLOCK_DELAY_MIN = 500000;
  41         /** Maximum time to wait before retry */
  42         const DEADLOCK_DELAY_MAX = 1500000;
  43
  44         /** How long before it is worth doing a dummy query to test the connection */
  45         const PING_TTL = 1.0;
  46         const PING_QUERY = 'SELECT 1 AS ping';
  47
  48         const TINY_WRITE_SEC = .010;
  49         const SLOW_WRITE_SEC = .500;
  50         const SMALL_WRITE_ROWS = 100;
  51
  52         /** @var string SQL query */
  53         protected $mLastQuery = '';
  54         /** @var float|bool UNIX timestamp of last write query */
  55         protected $mLastWriteTime = false;
  56         /** @var string|bool */
  57         protected $mPHPError = false;
  58         /** @var string */
  59         protected $mServer;
  60         /** @var string */
  61         protected $mUser;
  62         /** @var string */
  63         protected $mPassword;
  64         /** @var string */
  65         protected $mDBname;
  66         /** @var array[] $aliases Map of (table => (dbname, schema, prefix) map) */
  67         protected $tableAliases = [];
  68         /** @var bool Whether this PHP instance is for a CLI script */
  69         protected $cliMode;
  70         /** @var string Agent name for query profiling */
  71         protected $agent;
  72
  73         /** @var BagOStuff APC cache */
  74         protected $srvCache;
  75         /** @var LoggerInterface */
  76         protected $connLogger;
  77         /** @var LoggerInterface */
  78         protected $queryLogger;
  79         /** @var callback Error logging callback */
  80         protected $errorLogger;
  81
  82         /** @var resource Database connection */
  83         protected $mConn = null;
  84         /** @var bool */
  85         protected $mOpened = false;
  86
  87         /** @var array[] List of (callable, method name) */
  88         protected $mTrxIdleCallbacks = [];
  89         /** @var array[] List of (callable, method name) */
  90         protected $mTrxPreCommitCallbacks = [];
  91         /** @var array[] List of (callable, method name) */
  92         protected $mTrxEndCallbacks = [];
  93         /** @var callable[] Map of (name => callable) */
  94         protected $mTrxRecurringCallbacks = [];
  95         /** @var bool Whether to suppress triggering of transaction end callbacks */
  96         protected $mTrxEndCallbacksSuppressed = false;
  97
  98         /** @var string */
  99         protected $mTablePrefix = '';
 100         /** @var string */
 101         protected $mSchema = '';
 102         /** @var integer */
 103         protected $mFlags;
 104         /** @var array */
 105         protected $mLBInfo = [];
 106         /** @var bool|null */
 107         protected $mDefaultBigSelects = null;
 108         /** @var array|bool */
 109         protected $mSchemaVars = false;
 110         /** @var array */
 111         protected $mSessionVars = [];
 112         /** @var array|null */
 113         protected $preparedArgs;
 114         /** @var string|bool|null Stashed value of html_errors INI setting */
 115         protected $htmlErrors;
 116         /** @var string */
 117         protected $delimiter = ';';
 118         /** @var DatabaseDomain */
 119         protected $currentDomain;
 120
 121         /**
 122          * Either 1 if a transaction is active or 0 otherwise.
 123          * The other Trx fields may not be meaningfull if this is 0.
 124          *
 125          * @var int
 126          */
 127         protected $mTrxLevel = 0;
 128         /**
 129          * Either a short hexidecimal string if a transaction is active or ""
 130          *
 131          * @var string
 132          * @see Database::mTrxLevel
 133          */
 134         protected $mTrxShortId = '';
 135         /**
 136          * The UNIX time that the transaction started. Callers can assume that if
 137          * snapshot isolation is used, then the data is *at least* up to date to that
 138          * point (possibly more up-to-date since the first SELECT defines the snapshot).
 139          *
 140          * @var float|null
 141          * @see Database::mTrxLevel
 142          */
 143         private $mTrxTimestamp = null;
 144         /** @var float Lag estimate at the time of BEGIN */
 145         private $mTrxReplicaLag = null;
 146         /**
 147          * Remembers the function name given for starting the most recent transaction via begin().
 148          * Used to provide additional context for error reporting.
 149          *
 150          * @var string
 151          * @see Database::mTrxLevel
 152          */
 153         private $mTrxFname = null;
 154         /**
 155          * Record if possible write queries were done in the last transaction started
 156          *
 157          * @var bool
 158          * @see Database::mTrxLevel
 159          */
 160         private $mTrxDoneWrites = false;
 161         /**
 162          * Record if the current transaction was started implicitly due to DBO_TRX being set.
 163          *
 164          * @var bool
 165          * @see Database::mTrxLevel
 166          */
 167         private $mTrxAutomatic = false;
 168         /**
 169          * Array of levels of atomicity within transactions
 170          *
 171          * @var array
 172          */
 173         private $mTrxAtomicLevels = [];
 174         /**
 175          * Record if the current transaction was started implicitly by Database::startAtomic
 176          *
 177          * @var bool
 178          */
 179         private $mTrxAutomaticAtomic = false;
 180         /**
 181          * Track the write query callers of the current transaction
 182          *
 183          * @var string[]
 184          */
 185         private $mTrxWriteCallers = [];
 186         /**
 187          * @var float Seconds spent in write queries for the current transaction
 188          */
 189         private $mTrxWriteDuration = 0.0;
 190         /**
 191          * @var integer Number of write queries for the current transaction
 192          */
 193         private $mTrxWriteQueryCount = 0;
 194         /**
 195          * @var float Like mTrxWriteQueryCount but excludes lock-bound, easy to replicate, queries
 196          */
 197         private $mTrxWriteAdjDuration = 0.0;
 198         /**
 199          * @var integer Number of write queries counted in mTrxWriteAdjDuration
 200          */
 201         private $mTrxWriteAdjQueryCount = 0;
 202         /**
 203          * @var float RTT time estimate
 204          */
 205         private $mRTTEstimate = 0.0;
 206
 207         /** @var array Map of (name => 1) for locks obtained via lock() */
 208         private $mNamedLocksHeld = [];
 209         /** @var array Map of (table name => 1) for TEMPORARY tables */
 210         protected $mSessionTempTables = [];
 211
 212         /** @var IDatabase|null Lazy handle to the master DB this server replicates from */
 213         private $lazyMasterHandle;
 214
 215         /** @var float UNIX timestamp */
 216         protected $lastPing = 0.0;
 217
 218         /** @var int[] Prior mFlags values */
 219         private $priorFlags = [];
 220
 221         /** @var object|string Class name or object With profileIn/profileOut methods */
 222         protected $profiler;
 223         /** @var TransactionProfiler */
 224         protected $trxProfiler;
 225
 226         /**
 227          * Constructor and database handle and attempt to connect to the DB server
 228          *
 229          * IDatabase classes should not be constructed directly in external
 230          * code. Database::factory() should be used instead.
 231          *
 232          * @param array $params Parameters passed from Database::factory()
 233          */
 234         function __construct( array $params ) {
 235                 $server = $params['host'];
 236                 $user = $params['user'];
 237                 $password = $params['password'];
 238                 $dbName = $params['dbname'];
 239
 240                 $this->mSchema = $params['schema'];
 241                 $this->mTablePrefix = $params['tablePrefix'];
 242
 243                 $this->cliMode = $params['cliMode'];
 244                 // Agent name is added to SQL queries in a comment, so make sure it can't break out
 245                 $this->agent = str_replace( '/', '-', $params['agent'] );
 246
 247                 $this->mFlags = $params['flags'];
 248                 if ( $this->mFlags & self::DBO_DEFAULT ) {
 249                         if ( $this->cliMode ) {
 250                                 $this->mFlags &= ~self::DBO_TRX;
 251                         } else {
 252                                 $this->mFlags |= self::DBO_TRX;
 253                         }
 254                 }
 255
 256                 $this->mSessionVars = $params['variables'];
 257
 258                 $this->srvCache = isset( $params['srvCache'] )
 259                         ? $params['srvCache']
 260                         : new HashBagOStuff();
 261
 262                 $this->profiler = $params['profiler'];
 263                 $this->trxProfiler = $params['trxProfiler'];
 264                 $this->connLogger = $params['connLogger'];
 265                 $this->queryLogger = $params['queryLogger'];
 266                 $this->errorLogger = $params['errorLogger'];
 267
 268                 // Set initial dummy domain until open() sets the final DB/prefix
 269                 $this->currentDomain = DatabaseDomain::newUnspecified();
 270
 271                 if ( $user ) {
 272                         $this->open( $server, $user, $password, $dbName );
 273                 } elseif ( $this->requiresDatabaseUser() ) {
 274                         throw new InvalidArgumentException( "No database user provided." );
 275                 }
 276
 277                 // Set the domain object after open() sets the relevant fields
 278                 if ( $this->mDBname != '' ) {
 279                         // Domains with server scope but a table prefix are not used by IDatabase classes
 280                         $this->currentDomain = new DatabaseDomain( $this->mDBname, null, $this->mTablePrefix );
 281                 }
 282         }
 283
 284         /**
 285          * Construct a Database subclass instance given a database type and parameters
 286          *
 287          * This also connects to the database immediately upon object construction
 288          *
 289          * @param string $dbType A possible DB type (sqlite, mysql, postgres)
 290          * @param array $p Parameter map with keys:
 291          *   - host : The hostname of the DB server
 292          *   - user : The name of the database user the client operates under
 293          *   - password : The password for the database user
 294          *   - dbname : The name of the database to use where queries do not specify one.
 295          *      The database must exist or an error might be thrown. Setting this to the empty string
 296          *      will avoid any such errors and make the handle have no implicit database scope. This is
 297          *      useful for queries like SHOW STATUS, CREATE DATABASE, or DROP DATABASE. Note that a
 298          *      "database" in Postgres is rougly equivalent to an entire MySQL server. This the domain
 299          *      in which user names and such are defined, e.g. users are database-specific in Postgres.
 300          *   - schema : The database schema to use (if supported). A "schema" in Postgres is roughly
 301          *      equivalent to a "database" in MySQL. Note that MySQL and SQLite do not use schemas.
 302          *   - tablePrefix : Optional table prefix that is implicitly added on to all table names
 303          *      recognized in queries. This can be used in place of schemas for handle site farms.
 304          *   - flags : Optional bitfield of DBO_* constants that define connection, protocol,
 305          *      buffering, and transaction behavior. It is STRONGLY adviced to leave the DBO_DEFAULT
 306          *      flag in place UNLESS this this database simply acts as a key/value store.
 307          *   - driver: Optional name of a specific DB client driver. For MySQL, there is the old
 308          *      'mysql' driver and the newer 'mysqli' driver.
 309          *   - variables: Optional map of session variables to set after connecting. This can be
 310          *      used to adjust lock timeouts or encoding modes and the like.
 311          *   - connLogger: Optional PSR-3 logger interface instance.
 312          *   - queryLogger: Optional PSR-3 logger interface instance.
 313          *   - profiler: Optional class name or object with profileIn()/profileOut() methods.
 314          *      These will be called in query(), using a simplified version of the SQL that also
 315          *      includes the agent as a SQL comment.
 316          *   - trxProfiler: Optional TransactionProfiler instance.
 317          *   - errorLogger: Optional callback that takes an Exception and logs it.
 318          *   - cliMode: Whether to consider the execution context that of a CLI script.
 319          *   - agent: Optional name used to identify the end-user in query profiling/logging.
 320          *   - srvCache: Optional BagOStuff instance to an APC-style cache.
 321          * @return Database|null If the database driver or extension cannot be found
 322          * @throws InvalidArgumentException If the database driver or extension cannot be found
 323          * @since 1.18
 324          */
 325         final public static function factory( $dbType, $p = [] ) {
 326                 static $canonicalDBTypes = [
 327                         'mysql' => [ 'mysqli', 'mysql' ],
 328                         'postgres' => [],
 329                         'sqlite' => [],
 330                         'oracle' => [],
 331                         'mssql' => [],
 332                 ];
 333
 334                 $driver = false;
 335                 $dbType = strtolower( $dbType );
 336                 if ( isset( $canonicalDBTypes[$dbType] ) && $canonicalDBTypes[$dbType] ) {
 337                         $possibleDrivers = $canonicalDBTypes[$dbType];
 338                         if ( !empty( $p['driver'] ) ) {
 339                                 if ( in_array( $p['driver'], $possibleDrivers ) ) {
 340                                         $driver = $p['driver'];
 341                                 } else {
 342                                         throw new InvalidArgumentException( __METHOD__ .
 343                                                 " type '$dbType' does not support driver '{$p['driver']}'" );
 344                                 }
 345                         } else {
 346                                 foreach ( $possibleDrivers as $posDriver ) {
 347                                         if ( extension_loaded( $posDriver ) ) {
 348                                                 $driver = $posDriver;
 349                                                 break;
 350                                         }
 351                                 }
 352                         }
 353                 } else {
 354                         $driver = $dbType;
 355                 }
 356                 if ( $driver === false || $driver === '' ) {
 357                         throw new InvalidArgumentException( __METHOD__ .
 358                                 " no viable database extension found for type '$dbType'" );
 359                 }
 360
 361                 $class = 'Database' . ucfirst( $driver );
 362                 if ( class_exists( $class ) && is_subclass_of( $class, 'IDatabase' ) ) {
 363                         // Resolve some defaults for b/c
 364                         $p['host'] = isset( $p['host'] ) ? $p['host'] : false;
 365                         $p['user'] = isset( $p['user'] ) ? $p['user'] : false;
 366                         $p['password'] = isset( $p['password'] ) ? $p['password'] : false;
 367                         $p['dbname'] = isset( $p['dbname'] ) ? $p['dbname'] : false;
 368                         $p['flags'] = isset( $p['flags'] ) ? $p['flags'] : 0;
 369                         $p['variables'] = isset( $p['variables'] ) ? $p['variables'] : [];
 370                         $p['tablePrefix'] = isset( $p['tablePrefix'] ) ? $p['tablePrefix'] : '';
 371                         $p['schema'] = isset( $p['schema'] ) ? $p['schema'] : '';
 372                         $p['cliMode'] = isset( $p['cliMode'] ) ? $p['cliMode'] : ( PHP_SAPI === 'cli' );
 373                         $p['agent'] = isset( $p['agent'] ) ? $p['agent'] : '';
 374                         if ( !isset( $p['connLogger'] ) ) {
 375                                 $p['connLogger'] = new \Psr\Log\NullLogger();
 376                         }
 377                         if ( !isset( $p['queryLogger'] ) ) {
 378                                 $p['queryLogger'] = new \Psr\Log\NullLogger();
 379                         }
 380                         $p['profiler'] = isset( $p['profiler'] ) ? $p['profiler'] : null;
 381                         if ( !isset( $p['trxProfiler'] ) ) {
 382                                 $p['trxProfiler'] = new TransactionProfiler();
 383                         }
 384                         if ( !isset( $p['errorLogger'] ) ) {
 385                                 $p['errorLogger'] = function ( Exception $e ) {
 386                                         trigger_error( get_class( $e ) . ': ' . $e->getMessage(), E_WARNING );
 387                                 };
 388                         }
 389
 390                         $conn = new $class( $p );
 391                 } else {
 392                         $conn = null;
 393                 }
 394
 395                 return $conn;
 396         }
 397
 398         public function setLogger( LoggerInterface $logger ) {
 399                 $this->queryLogger = $logger;
 400         }
 401
 402         public function getServerInfo() {
 403                 return $this->getServerVersion();
 404         }
 405
 406         public function bufferResults( $buffer = null ) {
 407                 $res = !$this->getFlag( self::DBO_NOBUFFER );
 408                 if ( $buffer !== null ) {
 409                         $buffer
 410                                 ? $this->clearFlag( self::DBO_NOBUFFER )
 411                                 : $this->setFlag( self::DBO_NOBUFFER );
 412                 }
 413
 414                 return $res;
 415         }
 416
 417         /**
 418          * Turns on (false) or off (true) the automatic generation and sending
 419          * of a "we're sorry, but there has been a database error" page on
 420          * database errors. Default is on (false). When turned off, the
 421          * code should use lastErrno() and lastError() to handle the
 422          * situation as appropriate.
 423          *
 424          * Do not use this function outside of the Database classes.
 425          *
 426          * @param null|bool $ignoreErrors
 427          * @return bool The previous value of the flag.
 428          */
 429         protected function ignoreErrors( $ignoreErrors = null ) {
 430                 $res = $this->getFlag( self::DBO_IGNORE );
 431                 if ( $ignoreErrors !== null ) {
 432                         $ignoreErrors
 433                                 ? $this->setFlag( self::DBO_IGNORE )
 434                                 : $this->clearFlag( self::DBO_IGNORE );
 435                 }
 436
 437                 return $res;
 438         }
 439
 440         public function trxLevel() {
 441                 return $this->mTrxLevel;
 442         }
 443
 444         public function trxTimestamp() {
 445                 return $this->mTrxLevel ? $this->mTrxTimestamp : null;
 446         }
 447
 448         public function tablePrefix( $prefix = null ) {
 449                 $old = $this->mTablePrefix;
 450                 if ( $prefix !== null ) {
 451                         $this->mTablePrefix = $prefix;
 452                         $this->currentDomain = ( $this->mDBname != '' )
 453                                 ? new DatabaseDomain( $this->mDBname, null, $this->mTablePrefix )
 454                                 : DatabaseDomain::newUnspecified();
 455                 }
 456
 457                 return $old;
 458         }
 459
 460         public function dbSchema( $schema = null ) {
 461                 $old = $this->mSchema;
 462                 if ( $schema !== null ) {
 463                         $this->mSchema = $schema;
 464                 }
 465
 466                 return $old;
 467         }
 468
 469         public function getLBInfo( $name = null ) {
 470                 if ( is_null( $name ) ) {
 471                         return $this->mLBInfo;
 472                 } else {
 473                         if ( array_key_exists( $name, $this->mLBInfo ) ) {
 474                                 return $this->mLBInfo[$name];
 475                         } else {
 476                                 return null;
 477                         }
 478                 }
 479         }
 480
 481         public function setLBInfo( $name, $value = null ) {
 482                 if ( is_null( $value ) ) {
 483                         $this->mLBInfo = $name;
 484                 } else {
 485                         $this->mLBInfo[$name] = $value;
 486                 }
 487         }
 488
 489         public function setLazyMasterHandle( IDatabase $conn ) {
 490                 $this->lazyMasterHandle = $conn;
 491         }
 492
 493         /**
 494          * @return IDatabase|null
 495          * @see setLazyMasterHandle()
 496          * @since 1.27
 497          */
 498         protected function getLazyMasterHandle() {
 499                 return $this->lazyMasterHandle;
 500         }
 501
 502         public function implicitGroupby() {
 503                 return true;
 504         }
 505
 506         public function implicitOrderby() {
 507                 return true;
 508         }
 509
 510         public function lastQuery() {
 511                 return $this->mLastQuery;
 512         }
 513
 514         public function doneWrites() {
 515                 return (bool)$this->mLastWriteTime;
 516         }
 517
 518         public function lastDoneWrites() {
 519                 return $this->mLastWriteTime ?: false;
 520         }
 521
 522         public function writesPending() {
 523                 return $this->mTrxLevel && $this->mTrxDoneWrites;
 524         }
 525
 526         public function writesOrCallbacksPending() {
 527                 return $this->mTrxLevel && (
 528                         $this->mTrxDoneWrites || $this->mTrxIdleCallbacks || $this->mTrxPreCommitCallbacks
 529                 );
 530         }
 531
 532         public function pendingWriteQueryDuration( $type = self::ESTIMATE_TOTAL ) {
 533                 if ( !$this->mTrxLevel ) {
 534                         return false;
 535                 } elseif ( !$this->mTrxDoneWrites ) {
 536                         return 0.0;
 537                 }
 538
 539                 switch ( $type ) {
 540                         case self::ESTIMATE_DB_APPLY:
 541                                 $this->ping( $rtt );
 542                                 $rttAdjTotal = $this->mTrxWriteAdjQueryCount * $rtt;
 543                                 $applyTime = max( $this->mTrxWriteAdjDuration - $rttAdjTotal, 0 );
 544                                 // For omitted queries, make them count as something at least
 545                                 $omitted = $this->mTrxWriteQueryCount - $this->mTrxWriteAdjQueryCount;
 546                                 $applyTime += self::TINY_WRITE_SEC * $omitted;
 547
 548                                 return $applyTime;
 549                         default: // everything
 550                                 return $this->mTrxWriteDuration;
 551                 }
 552         }
 553
 554         public function pendingWriteCallers() {
 555                 return $this->mTrxLevel ? $this->mTrxWriteCallers : [];
 556         }
 557
 558         protected function pendingWriteAndCallbackCallers() {
 559                 if ( !$this->mTrxLevel ) {
 560                         return [];
 561                 }
 562
 563                 $fnames = $this->mTrxWriteCallers;
 564                 foreach ( [
 565                         $this->mTrxIdleCallbacks,
 566                         $this->mTrxPreCommitCallbacks,
 567                         $this->mTrxEndCallbacks
 568                 ] as $callbacks ) {
 569                         foreach ( $callbacks as $callback ) {
 570                                 $fnames[] = $callback[1];
 571                         }
 572                 }
 573
 574                 return $fnames;
 575         }
 576
 577         public function isOpen() {
 578                 return $this->mOpened;
 579         }
 580
 581         public function setFlag( $flag, $remember = self::REMEMBER_NOTHING ) {
 582                 if ( $remember === self::REMEMBER_PRIOR ) {
 583                         array_push( $this->priorFlags, $this->mFlags );
 584                 }
 585                 $this->mFlags |= $flag;
 586         }
 587
 588         public function clearFlag( $flag, $remember = self::REMEMBER_NOTHING ) {
 589                 if ( $remember === self::REMEMBER_PRIOR ) {
 590                         array_push( $this->priorFlags, $this->mFlags );
 591                 }
 592                 $this->mFlags &= ~$flag;
 593         }
 594
 595         public function restoreFlags( $state = self::RESTORE_PRIOR ) {
 596                 if ( !$this->priorFlags ) {
 597                         return;
 598                 }
 599
 600                 if ( $state === self::RESTORE_INITIAL ) {
 601                         $this->mFlags = reset( $this->priorFlags );
 602                         $this->priorFlags = [];
 603                 } else {
 604                         $this->mFlags = array_pop( $this->priorFlags );
 605                 }
 606         }
 607
 608         public function getFlag( $flag ) {
 609                 return !!( $this->mFlags & $flag );
 610         }
 611
 612         public function getProperty( $name ) {
 613                 return $this->$name;
 614         }
 615
 616         public function getDomainID() {
 617                 return $this->currentDomain->getId();
 618         }
 619
 620         final public function getWikiID() {
 621                 return $this->getDomainID();
 622         }
 623
 624         /**
 625          * Get information about an index into an object
 626          * @param string $table Table name
 627          * @param string $index Index name
 628          * @param string $fname Calling function name
 629          * @return mixed Database-specific index description class or false if the index does not exist
 630          */
 631         abstract function indexInfo( $table, $index, $fname = __METHOD__ );
 632
 633         /**
 634          * Wrapper for addslashes()
 635          *
 636          * @param string $s String to be slashed.
 637          * @return string Slashed string.
 638          */
 639         abstract function strencode( $s );
 640
 641         protected function installErrorHandler() {
 642                 $this->mPHPError = false;
 643                 $this->htmlErrors = ini_set( 'html_errors', '0' );
 644                 set_error_handler( [ $this, 'connectionErrorLogger' ] );
 645         }
 646
 647         /**
 648          * @return bool|string
 649          */
 650         protected function restoreErrorHandler() {
 651                 restore_error_handler();
 652                 if ( $this->htmlErrors !== false ) {
 653                         ini_set( 'html_errors', $this->htmlErrors );
 654                 }
 655                 if ( $this->mPHPError ) {
 656                         $error = preg_replace( '!\[<a.*</a>\]!', '', $this->mPHPError );
 657                         $error = preg_replace( '!^.*?:\s?(.*)$!', '$1', $error );
 658
 659                         return $error;
 660                 } else {
 661                         return false;
 662                 }
 663         }
 664
 665         /**
 666          * This method should not be used outside of Database classes
 667          *
 668          * @param int $errno
 669          * @param string $errstr
 670          */
 671         public function connectionErrorLogger( $errno, $errstr ) {
 672                 $this->mPHPError = $errstr;
 673         }
 674
 675         /**
 676          * Create a log context to pass to PSR-3 logger functions.
 677          *
 678          * @param array $extras Additional data to add to context
 679          * @return array
 680          */
 681         protected function getLogContext( array $extras = [] ) {
 682                 return array_merge(
 683                         [
 684                                 'db_server' => $this->mServer,
 685                                 'db_name' => $this->mDBname,
 686                                 'db_user' => $this->mUser,
 687                         ],
 688                         $extras
 689                 );
 690         }
 691
 692         public function close() {
 693                 if ( $this->mConn ) {
 694                         if ( $this->trxLevel() ) {
 695                                 $this->commit( __METHOD__, self::FLUSHING_INTERNAL );
 696                         }
 697
 698                         $closed = $this->closeConnection();
 699                         $this->mConn = false;
 700                 } elseif ( $this->mTrxIdleCallbacks || $this->mTrxEndCallbacks ) { // sanity
 701                         throw new RuntimeException( "Transaction callbacks still pending." );
 702                 } else {
 703                         $closed = true;
 704                 }
 705                 $this->mOpened = false;
 706
 707                 return $closed;
 708         }
 709
 710         /**
 711          * Make sure isOpen() returns true as a sanity check
 712          *
 713          * @throws DBUnexpectedError
 714          */
 715         protected function assertOpen() {
 716                 if ( !$this->isOpen() ) {
 717                         throw new DBUnexpectedError( $this, "DB connection was already closed." );
 718                 }
 719         }
 720
 721         /**
 722          * Closes underlying database connection
 723          * @since 1.20
 724          * @return bool Whether connection was closed successfully
 725          */
 726         abstract protected function closeConnection();
 727
 728         public function reportConnectionError( $error = 'Unknown error' ) {
 729                 $myError = $this->lastError();
 730                 if ( $myError ) {
 731                         $error = $myError;
 732                 }
 733
 734                 # New method
 735                 throw new DBConnectionError( $this, $error );
 736         }
 737
 738         /**
 739          * The DBMS-dependent part of query()
 740          *
 741          * @param string $sql SQL query.
 742          * @return ResultWrapper|bool Result object to feed to fetchObject,
 743          *   fetchRow, ...; or false on failure
 744          */
 745         abstract protected function doQuery( $sql );
 746
 747         /**
 748          * Determine whether a query writes to the DB.
 749          * Should return true if unsure.
 750          *
 751          * @param string $sql
 752          * @return bool
 753          */
 754         protected function isWriteQuery( $sql ) {
 755                 return !preg_match(
 756                         '/^(?:SELECT|BEGIN|ROLLBACK|COMMIT|SET|SHOW|EXPLAIN|\(SELECT)\b/i', $sql );
 757         }
 758
 759         /**
 760          * @param $sql
 761          * @return string|null
 762          */
 763         protected function getQueryVerb( $sql ) {
 764                 return preg_match( '/^\s*([a-z]+)/i', $sql, $m ) ? strtoupper( $m[1] ) : null;
 765         }
 766
 767         /**
 768          * Determine whether a SQL statement is sensitive to isolation level.
 769          * A SQL statement is considered transactable if its result could vary
 770          * depending on the transaction isolation level. Operational commands
 771          * such as 'SET' and 'SHOW' are not considered to be transactable.
 772          *
 773          * @param string $sql
 774          * @return bool
 775          */
 776         protected function isTransactableQuery( $sql ) {
 777                 $verb = $this->getQueryVerb( $sql );
 778                 return !in_array( $verb, [ 'BEGIN', 'COMMIT', 'ROLLBACK', 'SHOW', 'SET' ], true );
 779         }
 780
 781         /**
 782          * @param string $sql A SQL query
 783          * @return bool Whether $sql is SQL for creating/dropping a new TEMPORARY table
 784          */
 785         protected function registerTempTableOperation( $sql ) {
 786                 if ( preg_match(
 787                         '/^CREATE\s+TEMPORARY\s+TABLE\s+(?:IF\s+NOT\s+EXISTS\s+)?[`"\']?(\w+)[`"\']?/i',
 788                         $sql,
 789                         $matches
 790                 ) ) {
 791                         $this->mSessionTempTables[$matches[1]] = 1;
 792
 793                         return true;
 794                 } elseif ( preg_match(
 795                         '/^DROP\s+(?:TEMPORARY\s+)?TABLE\s+(?:IF\s+EXISTS\s+)?[`"\']?(\w+)[`"\']?/i',
 796                         $sql,
 797                         $matches
 798                 ) ) {
 799                         unset( $this->mSessionTempTables[$matches[1]] );
 800
 801                         return true;
 802                 } elseif ( preg_match(
 803                         '/^(?:INSERT\s+(?:\w+\s+)?INTO|UPDATE|DELETE\s+FROM)\s+[`"\']?(\w+)[`"\']?/i',
 804                         $sql,
 805                         $matches
 806                 ) ) {
 807                         return isset( $this->mSessionTempTables[$matches[1]] );
 808                 }
 809
 810                 return false;
 811         }
 812
 813         public function query( $sql, $fname = __METHOD__, $tempIgnore = false ) {
 814                 $priorWritesPending = $this->writesOrCallbacksPending();
 815                 $this->mLastQuery = $sql;
 816
 817                 $isWrite = $this->isWriteQuery( $sql ) && !$this->registerTempTableOperation( $sql );
 818                 if ( $isWrite ) {
 819                         $reason = $this->getReadOnlyReason();
 820                         if ( $reason !== false ) {
 821                                 throw new DBReadOnlyError( $this, "Database is read-only: $reason" );
 822                         }
 823                         # Set a flag indicating that writes have been done
 824                         $this->mLastWriteTime = microtime( true );
 825                 }
 826
 827                 // Add trace comment to the begin of the sql string, right after the operator.
 828                 // Or, for one-word queries (like "BEGIN" or COMMIT") add it to the end (bug 42598)
 829                 $commentedSql = preg_replace( '/\s|$/', " /* $fname {$this->agent} */ ", $sql, 1 );
 830
 831                 # Start implicit transactions that wrap the request if DBO_TRX is enabled
 832                 if ( !$this->mTrxLevel && $this->getFlag( self::DBO_TRX )
 833                         && $this->isTransactableQuery( $sql )
 834                 ) {
 835                         $this->begin( __METHOD__ . " ($fname)", self::TRANSACTION_INTERNAL );
 836                         $this->mTrxAutomatic = true;
 837                 }
 838
 839                 # Keep track of whether the transaction has write queries pending
 840                 if ( $this->mTrxLevel && !$this->mTrxDoneWrites && $isWrite ) {
 841                         $this->mTrxDoneWrites = true;
 842                         $this->trxProfiler->transactionWritingIn(
 843                                 $this->mServer, $this->mDBname, $this->mTrxShortId );
 844                 }
 845
 846                 if ( $this->getFlag( self::DBO_DEBUG ) ) {
 847                         $this->queryLogger->debug( "{$this->mDBname} {$commentedSql}" );
 848                 }
 849
 850                 # Avoid fatals if close() was called
 851                 $this->assertOpen();
 852
 853                 # Send the query to the server
 854                 $ret = $this->doProfiledQuery( $sql, $commentedSql, $isWrite, $fname );
 855
 856                 # Try reconnecting if the connection was lost
 857                 if ( false === $ret && $this->wasErrorReissuable() ) {
 858                         $recoverable = $this->canRecoverFromDisconnect( $sql, $priorWritesPending );
 859                         # Stash the last error values before anything might clear them
 860                         $lastError = $this->lastError();
 861                         $lastErrno = $this->lastErrno();
 862                         # Update state tracking to reflect transaction loss due to disconnection
 863                         $this->handleSessionLoss();
 864                         if ( $this->reconnect() ) {
 865                                 $msg = __METHOD__ . ": lost connection to {$this->getServer()}; reconnected";
 866                                 $this->connLogger->warning( $msg );
 867                                 $this->queryLogger->warning(
 868                                         "$msg:\n" . ( new RuntimeException() )->getTraceAsString() );
 869
 870                                 if ( !$recoverable ) {
 871                                         # Callers may catch the exception and continue to use the DB
 872                                         $this->reportQueryError( $lastError, $lastErrno, $sql, $fname );
 873                                 } else {
 874                                         # Should be safe to silently retry the query
 875                                         $ret = $this->doProfiledQuery( $sql, $commentedSql, $isWrite, $fname );
 876                                 }
 877                         } else {
 878                                 $msg = __METHOD__ . ": lost connection to {$this->getServer()} permanently";
 879                                 $this->connLogger->error( $msg );
 880                         }
 881                 }
 882
 883                 if ( false === $ret ) {
 884                         # Deadlocks cause the entire transaction to abort, not just the statement.
 885                         # http://dev.mysql.com/doc/refman/5.7/en/innodb-error-handling.html
 886                         # https://www.postgresql.org/docs/9.1/static/explicit-locking.html
 887                         if ( $this->wasDeadlock() ) {
 888                                 if ( $this->explicitTrxActive() || $priorWritesPending ) {
 889                                         $tempIgnore = false; // not recoverable
 890                                 }
 891                                 # Update state tracking to reflect transaction loss
 892                                 $this->handleSessionLoss();
 893                         }
 894
 895                         $this->reportQueryError(
 896                                 $this->lastError(), $this->lastErrno(), $sql, $fname, $tempIgnore );
 897                 }
 898
 899                 $res = $this->resultObject( $ret );
 900
 901                 return $res;
 902         }
 903
 904         private function doProfiledQuery( $sql, $commentedSql, $isWrite, $fname ) {
 905                 $isMaster = !is_null( $this->getLBInfo( 'master' ) );
 906                 # generalizeSQL() will probably cut down the query to reasonable
 907                 # logging size most of the time. The substr is really just a sanity check.
 908                 if ( $isMaster ) {
 909                         $queryProf = 'query-m: ' . substr( self::generalizeSQL( $sql ), 0, 255 );
 910                 } else {
 911                         $queryProf = 'query: ' . substr( self::generalizeSQL( $sql ), 0, 255 );
 912                 }
 913
 914                 # Include query transaction state
 915                 $queryProf .= $this->mTrxShortId ? " [TRX#{$this->mTrxShortId}]" : "";
 916
 917                 $startTime = microtime( true );
 918                 if ( $this->profiler ) {
 919                         call_user_func( [ $this->profiler, 'profileIn' ], $queryProf );
 920                 }
 921                 $ret = $this->doQuery( $commentedSql );
 922                 if ( $this->profiler ) {
 923                         call_user_func( [ $this->profiler, 'profileOut' ], $queryProf );
 924                 }
 925                 $queryRuntime = max( microtime( true ) - $startTime, 0.0 );
 926
 927                 unset( $queryProfSection ); // profile out (if set)
 928
 929                 if ( $ret !== false ) {
 930                         $this->lastPing = $startTime;
 931                         if ( $isWrite && $this->mTrxLevel ) {
 932                                 $this->updateTrxWriteQueryTime( $sql, $queryRuntime );
 933                                 $this->mTrxWriteCallers[] = $fname;
 934                         }
 935                 }
 936
 937                 if ( $sql === self::PING_QUERY ) {
 938                         $this->mRTTEstimate = $queryRuntime;
 939                 }
 940
 941                 $this->trxProfiler->recordQueryCompletion(
 942                         $queryProf, $startTime, $isWrite, $this->affectedRows()
 943                 );
 944                 $this->queryLogger->debug( $sql, [
 945                         'method' => $fname,
 946                         'master' => $isMaster,
 947                         'runtime' => $queryRuntime,
 948                 ] );
 949
 950                 return $ret;
 951         }
 952
 953         /**
 954          * Update the estimated run-time of a query, not counting large row lock times
 955          *
 956          * LoadBalancer can be set to rollback transactions that will create huge replication
 957          * lag. It bases this estimate off of pendingWriteQueryDuration(). Certain simple
 958          * queries, like inserting a row can take a long time due to row locking. This method
 959          * uses some simple heuristics to discount those cases.
 960          *
 961          * @param string $sql A SQL write query
 962          * @param float $runtime Total runtime, including RTT
 963          */
 964         private function updateTrxWriteQueryTime( $sql, $runtime ) {
 965                 // Whether this is indicative of replica DB runtime (except for RBR or ws_repl)
 966                 $indicativeOfReplicaRuntime = true;
 967                 if ( $runtime > self::SLOW_WRITE_SEC ) {
 968                         $verb = $this->getQueryVerb( $sql );
 969                         // insert(), upsert(), replace() are fast unless bulky in size or blocked on locks
 970                         if ( $verb === 'INSERT' ) {
 971                                 $indicativeOfReplicaRuntime = $this->affectedRows() > self::SMALL_WRITE_ROWS;
 972                         } elseif ( $verb === 'REPLACE' ) {
 973                                 $indicativeOfReplicaRuntime = $this->affectedRows() > self::SMALL_WRITE_ROWS / 2;
 974                         }
 975                 }
 976
 977                 $this->mTrxWriteDuration += $runtime;
 978                 $this->mTrxWriteQueryCount += 1;
 979                 if ( $indicativeOfReplicaRuntime ) {
 980                         $this->mTrxWriteAdjDuration += $runtime;
 981                         $this->mTrxWriteAdjQueryCount += 1;
 982                 }
 983         }
 984
 985         private function canRecoverFromDisconnect( $sql, $priorWritesPending ) {
 986                 # Transaction dropped; this can mean lost writes, or REPEATABLE-READ snapshots.
 987                 # Dropped connections also mean that named locks are automatically released.
 988                 # Only allow error suppression in autocommit mode or when the lost transaction
 989                 # didn't matter anyway (aside from DBO_TRX snapshot loss).
 990                 if ( $this->mNamedLocksHeld ) {
 991                         return false; // possible critical section violation
 992                 } elseif ( $sql === 'COMMIT' ) {
 993                         return !$priorWritesPending; // nothing written anyway? (T127428)
 994                 } elseif ( $sql === 'ROLLBACK' ) {
 995                         return true; // transaction lost...which is also what was requested :)
 996                 } elseif ( $this->explicitTrxActive() ) {
 997                         return false; // don't drop atomocity
 998                 } elseif ( $priorWritesPending ) {
 999                         return false; // prior writes lost from implicit transaction
1000                 }
1001
1002                 return true;
1003         }
1004
1005         private function handleSessionLoss() {
1006                 $this->mTrxLevel = 0;
1007                 $this->mTrxIdleCallbacks = []; // bug 65263
1008                 $this->mTrxPreCommitCallbacks = []; // bug 65263
1009                 $this->mSessionTempTables = [];
1010                 $this->mNamedLocksHeld = [];
1011                 try {
1012                         // Handle callbacks in mTrxEndCallbacks
1013                         $this->runOnTransactionIdleCallbacks( self::TRIGGER_ROLLBACK );
1014                         $this->runTransactionListenerCallbacks( self::TRIGGER_ROLLBACK );
1015                         return null;
1016                 } catch ( Exception $e ) {
1017                         // Already logged; move on...
1018                         return $e;
1019                 }
1020         }
1021
1022         public function reportQueryError( $error, $errno, $sql, $fname, $tempIgnore = false ) {
1023                 if ( $this->ignoreErrors() || $tempIgnore ) {
1024                         $this->queryLogger->debug( "SQL ERROR (ignored): $error\n" );
1025                 } else {
1026                         $sql1line = mb_substr( str_replace( "\n", "\\n", $sql ), 0, 5 * 1024 );
1027                         $this->queryLogger->error(
1028                                 "{fname}\t{db_server}\t{errno}\t{error}\t{sql1line}",
1029                                 $this->getLogContext( [
1030                                         'method' => __METHOD__,
1031                                         'errno' => $errno,
1032                                         'error' => $error,
1033                                         'sql1line' => $sql1line,
1034                                         'fname' => $fname,
1035                                 ] )
1036                         );
1037                         $this->queryLogger->debug( "SQL ERROR: " . $error . "\n" );
1038                         throw new DBQueryError( $this, $error, $errno, $sql, $fname );
1039                 }
1040         }
1041
1042         public function freeResult( $res ) {
1043         }
1044
1045         public function selectField(
1046                 $table, $var, $cond = '', $fname = __METHOD__, $options = []
1047         ) {
1048                 if ( $var === '*' ) { // sanity
1049                         throw new DBUnexpectedError( $this, "Cannot use a * field: got '$var'" );
1050                 }
1051
1052                 if ( !is_array( $options ) ) {
1053                         $options = [ $options ];
1054                 }
1055
1056                 $options['LIMIT'] = 1;
1057
1058                 $res = $this->select( $table, $var, $cond, $fname, $options );
1059                 if ( $res === false || !$this->numRows( $res ) ) {
1060                         return false;
1061                 }
1062
1063                 $row = $this->fetchRow( $res );
1064
1065                 if ( $row !== false ) {
1066                         return reset( $row );
1067                 } else {
1068                         return false;
1069                 }
1070         }
1071
1072         public function selectFieldValues(
1073                 $table, $var, $cond = '', $fname = __METHOD__, $options = [], $join_conds = []
1074         ) {
1075                 if ( $var === '*' ) { // sanity
1076                         throw new DBUnexpectedError( $this, "Cannot use a * field" );
1077                 } elseif ( !is_string( $var ) ) { // sanity
1078                         throw new DBUnexpectedError( $this, "Cannot use an array of fields" );
1079                 }
1080
1081                 if ( !is_array( $options ) ) {
1082                         $options = [ $options ];
1083                 }
1084
1085                 $res = $this->select( $table, $var, $cond, $fname, $options, $join_conds );
1086                 if ( $res === false ) {
1087                         return false;
1088                 }
1089
1090                 $values = [];
1091                 foreach ( $res as $row ) {
1092                         $values[] = $row->$var;
1093                 }
1094
1095                 return $values;
1096         }
1097
1098         /**
1099          * Returns an optional USE INDEX clause to go after the table, and a
1100          * string to go at the end of the query.
1101          *
1102          * @param array $options Associative array of options to be turned into
1103          *   an SQL query, valid keys are listed in the function.
1104          * @return array
1105          * @see Database::select()
1106          */
1107         protected function makeSelectOptions( $options ) {
1108                 $preLimitTail = $postLimitTail = '';
1109                 $startOpts = '';
1110
1111                 $noKeyOptions = [];
1112
1113                 foreach ( $options as $key => $option ) {
1114                         if ( is_numeric( $key ) ) {
1115                                 $noKeyOptions[$option] = true;
1116                         }
1117                 }
1118
1119                 $preLimitTail .= $this->makeGroupByWithHaving( $options );
1120
1121                 $preLimitTail .= $this->makeOrderBy( $options );
1122
1123                 // if (isset($options['LIMIT'])) {
1124                 //      $tailOpts .= $this->limitResult('', $options['LIMIT'],
1125                 //              isset($options['OFFSET']) ? $options['OFFSET']
1126                 //              : false);
1127                 // }
1128
1129                 if ( isset( $noKeyOptions['FOR UPDATE'] ) ) {
1130                         $postLimitTail .= ' FOR UPDATE';
1131                 }
1132
1133                 if ( isset( $noKeyOptions['LOCK IN SHARE MODE'] ) ) {
1134                         $postLimitTail .= ' LOCK IN SHARE MODE';
1135                 }
1136
1137                 if ( isset( $noKeyOptions['DISTINCT'] ) || isset( $noKeyOptions['DISTINCTROW'] ) ) {
1138                         $startOpts .= 'DISTINCT';
1139                 }
1140
1141                 # Various MySQL extensions
1142                 if ( isset( $noKeyOptions['STRAIGHT_JOIN'] ) ) {
1143                         $startOpts .= ' /*! STRAIGHT_JOIN */';
1144                 }
1145
1146                 if ( isset( $noKeyOptions['HIGH_PRIORITY'] ) ) {
1147                         $startOpts .= ' HIGH_PRIORITY';
1148                 }
1149
1150                 if ( isset( $noKeyOptions['SQL_BIG_RESULT'] ) ) {
1151                         $startOpts .= ' SQL_BIG_RESULT';
1152                 }
1153
1154                 if ( isset( $noKeyOptions['SQL_BUFFER_RESULT'] ) ) {
1155                         $startOpts .= ' SQL_BUFFER_RESULT';
1156                 }
1157
1158                 if ( isset( $noKeyOptions['SQL_SMALL_RESULT'] ) ) {
1159                         $startOpts .= ' SQL_SMALL_RESULT';
1160                 }
1161
1162                 if ( isset( $noKeyOptions['SQL_CALC_FOUND_ROWS'] ) ) {
1163                         $startOpts .= ' SQL_CALC_FOUND_ROWS';
1164                 }
1165
1166                 if ( isset( $noKeyOptions['SQL_CACHE'] ) ) {
1167                         $startOpts .= ' SQL_CACHE';
1168                 }
1169
1170                 if ( isset( $noKeyOptions['SQL_NO_CACHE'] ) ) {
1171                         $startOpts .= ' SQL_NO_CACHE';
1172                 }
1173
1174                 if ( isset( $options['USE INDEX'] ) && is_string( $options['USE INDEX'] ) ) {
1175                         $useIndex = $this->useIndexClause( $options['USE INDEX'] );
1176                 } else {
1177                         $useIndex = '';
1178                 }
1179                 if ( isset( $options['IGNORE INDEX'] ) && is_string( $options['IGNORE INDEX'] ) ) {
1180                         $ignoreIndex = $this->ignoreIndexClause( $options['IGNORE INDEX'] );
1181                 } else {
1182                         $ignoreIndex = '';
1183                 }
1184
1185                 return [ $startOpts, $useIndex, $preLimitTail, $postLimitTail, $ignoreIndex ];
1186         }
1187
1188         /**
1189          * Returns an optional GROUP BY with an optional HAVING
1190          *
1191          * @param array $options Associative array of options
1192          * @return string
1193          * @see Database::select()
1194          * @since 1.21
1195          */
1196         protected function makeGroupByWithHaving( $options ) {
1197                 $sql = '';
1198                 if ( isset( $options['GROUP BY'] ) ) {
1199                         $gb = is_array( $options['GROUP BY'] )
1200                                 ? implode( ',', $options['GROUP BY'] )
1201                                 : $options['GROUP BY'];
1202                         $sql .= ' GROUP BY ' . $gb;
1203                 }
1204                 if ( isset( $options['HAVING'] ) ) {
1205                         $having = is_array( $options['HAVING'] )
1206                                 ? $this->makeList( $options['HAVING'], self::LIST_AND )
1207                                 : $options['HAVING'];
1208                         $sql .= ' HAVING ' . $having;
1209                 }
1210
1211                 return $sql;
1212         }
1213
1214         /**
1215          * Returns an optional ORDER BY
1216          *
1217          * @param array $options Associative array of options
1218          * @return string
1219          * @see Database::select()
1220          * @since 1.21
1221          */
1222         protected function makeOrderBy( $options ) {
1223                 if ( isset( $options['ORDER BY'] ) ) {
1224                         $ob = is_array( $options['ORDER BY'] )
1225                                 ? implode( ',', $options['ORDER BY'] )
1226                                 : $options['ORDER BY'];
1227
1228                         return ' ORDER BY ' . $ob;
1229                 }
1230
1231                 return '';
1232         }
1233
1234         public function select( $table, $vars, $conds = '', $fname = __METHOD__,
1235                 $options = [], $join_conds = [] ) {
1236                 $sql = $this->selectSQLText( $table, $vars, $conds, $fname, $options, $join_conds );
1237
1238                 return $this->query( $sql, $fname );
1239         }
1240
1241         public function selectSQLText( $table, $vars, $conds = '', $fname = __METHOD__,
1242                 $options = [], $join_conds = []
1243         ) {
1244                 if ( is_array( $vars ) ) {
1245                         $vars = implode( ',', $this->fieldNamesWithAlias( $vars ) );
1246                 }
1247
1248                 $options = (array)$options;
1249                 $useIndexes = ( isset( $options['USE INDEX'] ) && is_array( $options['USE INDEX'] ) )
1250                         ? $options['USE INDEX']
1251                         : [];
1252                 $ignoreIndexes = (
1253                         isset( $options['IGNORE INDEX'] ) &&
1254                         is_array( $options['IGNORE INDEX'] )
1255                 )
1256                         ? $options['IGNORE INDEX']
1257                         : [];
1258
1259                 if ( is_array( $table ) ) {
1260                         $from = ' FROM ' .
1261                                 $this->tableNamesWithIndexClauseOrJOIN(
1262                                         $table, $useIndexes, $ignoreIndexes, $join_conds );
1263                 } elseif ( $table != '' ) {
1264                         if ( $table[0] == ' ' ) {
1265                                 $from = ' FROM ' . $table;
1266                         } else {
1267                                 $from = ' FROM ' .
1268                                         $this->tableNamesWithIndexClauseOrJOIN(
1269                                                 [ $table ], $useIndexes, $ignoreIndexes, [] );
1270                         }
1271                 } else {
1272                         $from = '';
1273                 }
1274
1275                 list( $startOpts, $useIndex, $preLimitTail, $postLimitTail, $ignoreIndex ) =
1276                         $this->makeSelectOptions( $options );
1277
1278                 if ( !empty( $conds ) ) {
1279                         if ( is_array( $conds ) ) {
1280                                 $conds = $this->makeList( $conds, self::LIST_AND );
1281                         }
1282                         $sql = "SELECT $startOpts $vars $from $useIndex $ignoreIndex " .
1283                                 "WHERE $conds $preLimitTail";
1284                 } else {
1285                         $sql = "SELECT $startOpts $vars $from $useIndex $ignoreIndex $preLimitTail";
1286                 }
1287
1288                 if ( isset( $options['LIMIT'] ) ) {
1289                         $sql = $this->limitResult( $sql, $options['LIMIT'],
1290                                 isset( $options['OFFSET'] ) ? $options['OFFSET'] : false );
1291                 }
1292                 $sql = "$sql $postLimitTail";
1293
1294                 if ( isset( $options['EXPLAIN'] ) ) {
1295                         $sql = 'EXPLAIN ' . $sql;
1296                 }
1297
1298                 return $sql;
1299         }
1300
1301         public function selectRow( $table, $vars, $conds, $fname = __METHOD__,
1302                 $options = [], $join_conds = []
1303         ) {
1304                 $options = (array)$options;
1305                 $options['LIMIT'] = 1;
1306                 $res = $this->select( $table, $vars, $conds, $fname, $options, $join_conds );
1307
1308                 if ( $res === false ) {
1309                         return false;
1310                 }
1311
1312                 if ( !$this->numRows( $res ) ) {
1313                         return false;
1314                 }
1315
1316                 $obj = $this->fetchObject( $res );
1317
1318                 return $obj;
1319         }
1320
1321         public function estimateRowCount(
1322                 $table, $vars = '*', $conds = '', $fname = __METHOD__, $options = []
1323         ) {
1324                 $rows = 0;
1325                 $res = $this->select( $table, [ 'rowcount' => 'COUNT(*)' ], $conds, $fname, $options );
1326
1327                 if ( $res ) {
1328                         $row = $this->fetchRow( $res );
1329                         $rows = ( isset( $row['rowcount'] ) ) ? (int)$row['rowcount'] : 0;
1330                 }
1331
1332                 return $rows;
1333         }
1334
1335         public function selectRowCount(
1336                 $tables, $vars = '*', $conds = '', $fname = __METHOD__, $options = [], $join_conds = []
1337         ) {
1338                 $rows = 0;
1339                 $sql = $this->selectSQLText( $tables, '1', $conds, $fname, $options, $join_conds );
1340                 $res = $this->query( "SELECT COUNT(*) AS rowcount FROM ($sql) tmp_count", $fname );
1341
1342                 if ( $res ) {
1343                         $row = $this->fetchRow( $res );
1344                         $rows = ( isset( $row['rowcount'] ) ) ? (int)$row['rowcount'] : 0;
1345                 }
1346
1347                 return $rows;
1348         }
1349
1350         /**
1351          * Removes most variables from an SQL query and replaces them with X or N for numbers.
1352          * It's only slightly flawed. Don't use for anything important.
1353          *
1354          * @param string $sql A SQL Query
1355          *
1356          * @return string
1357          */
1358         protected static function generalizeSQL( $sql ) {
1359                 # This does the same as the regexp below would do, but in such a way
1360                 # as to avoid crashing php on some large strings.
1361                 # $sql = preg_replace( "/'([^\\\\']|\\\\.)*'|\"([^\\\\\"]|\\\\.)*\"/", "'X'", $sql );
1362
1363                 $sql = str_replace( "\\\\", '', $sql );
1364                 $sql = str_replace( "\\'", '', $sql );
1365                 $sql = str_replace( "\\\"", '', $sql );
1366                 $sql = preg_replace( "/'.*'/s", "'X'", $sql );
1367                 $sql = preg_replace( '/".*"/s', "'X'", $sql );
1368
1369                 # All newlines, tabs, etc replaced by single space
1370                 $sql = preg_replace( '/\s+/', ' ', $sql );
1371
1372                 # All numbers => N,
1373                 # except the ones surrounded by characters, e.g. l10n
1374                 $sql = preg_replace( '/-?\d+(,-?\d+)+/s', 'N,...,N', $sql );
1375                 $sql = preg_replace( '/(?<![a-zA-Z])-?\d+(?![a-zA-Z])/s', 'N', $sql );
1376
1377                 return $sql;
1378         }
1379
1380         public function fieldExists( $table, $field, $fname = __METHOD__ ) {
1381                 $info = $this->fieldInfo( $table, $field );
1382
1383                 return (bool)$info;
1384         }
1385
1386         public function indexExists( $table, $index, $fname = __METHOD__ ) {
1387                 if ( !$this->tableExists( $table ) ) {
1388                         return null;
1389                 }
1390
1391                 $info = $this->indexInfo( $table, $index, $fname );
1392                 if ( is_null( $info ) ) {
1393                         return null;
1394                 } else {
1395                         return $info !== false;
1396                 }
1397         }
1398
1399         public function tableExists( $table, $fname = __METHOD__ ) {
1400                 $tableRaw = $this->tableName( $table, 'raw' );
1401                 if ( isset( $this->mSessionTempTables[$tableRaw] ) ) {
1402                         return true; // already known to exist
1403                 }
1404
1405                 $table = $this->tableName( $table );
1406                 $old = $this->ignoreErrors( true );
1407                 $res = $this->query( "SELECT 1 FROM $table LIMIT 1", $fname );
1408                 $this->ignoreErrors( $old );
1409
1410                 return (bool)$res;
1411         }
1412
1413         public function indexUnique( $table, $index ) {
1414                 $indexInfo = $this->indexInfo( $table, $index );
1415
1416                 if ( !$indexInfo ) {
1417                         return null;
1418                 }
1419
1420                 return !$indexInfo[0]->Non_unique;
1421         }
1422
1423         /**
1424          * Helper for Database::insert().
1425          *
1426          * @param array $options
1427          * @return string
1428          */
1429         protected function makeInsertOptions( $options ) {
1430                 return implode( ' ', $options );
1431         }
1432
1433         public function insert( $table, $a, $fname = __METHOD__, $options = [] ) {
1434                 # No rows to insert, easy just return now
1435                 if ( !count( $a ) ) {
1436                         return true;
1437                 }
1438
1439                 $table = $this->tableName( $table );
1440
1441                 if ( !is_array( $options ) ) {
1442                         $options = [ $options ];
1443                 }
1444
1445                 $fh = null;
1446                 if ( isset( $options['fileHandle'] ) ) {
1447                         $fh = $options['fileHandle'];
1448                 }
1449                 $options = $this->makeInsertOptions( $options );
1450
1451                 if ( isset( $a[0] ) && is_array( $a[0] ) ) {
1452                         $multi = true;
1453                         $keys = array_keys( $a[0] );
1454                 } else {
1455                         $multi = false;
1456                         $keys = array_keys( $a );
1457                 }
1458
1459                 $sql = 'INSERT ' . $options .
1460                         " INTO $table (" . implode( ',', $keys ) . ') VALUES ';
1461
1462                 if ( $multi ) {
1463                         $first = true;
1464                         foreach ( $a as $row ) {
1465                                 if ( $first ) {
1466                                         $first = false;
1467                                 } else {
1468                                         $sql .= ',';
1469                                 }
1470                                 $sql .= '(' . $this->makeList( $row ) . ')';
1471                         }
1472                 } else {
1473                         $sql .= '(' . $this->makeList( $a ) . ')';
1474                 }
1475
1476                 if ( $fh !== null && false === fwrite( $fh, $sql ) ) {
1477                         return false;
1478                 } elseif ( $fh !== null ) {
1479                         return true;
1480                 }
1481
1482                 return (bool)$this->query( $sql, $fname );
1483         }
1484
1485         /**
1486          * Make UPDATE options array for Database::makeUpdateOptions
1487          *
1488          * @param array $options
1489          * @return array
1490          */
1491         protected function makeUpdateOptionsArray( $options ) {
1492                 if ( !is_array( $options ) ) {
1493                         $options = [ $options ];
1494                 }
1495
1496                 $opts = [];
1497
1498                 if ( in_array( 'IGNORE', $options ) ) {
1499                         $opts[] = 'IGNORE';
1500                 }
1501
1502                 return $opts;
1503         }
1504
1505         /**
1506          * Make UPDATE options for the Database::update function
1507          *
1508          * @param array $options The options passed to Database::update
1509          * @return string
1510          */
1511         protected function makeUpdateOptions( $options ) {
1512                 $opts = $this->makeUpdateOptionsArray( $options );
1513
1514                 return implode( ' ', $opts );
1515         }
1516
1517         public function update( $table, $values, $conds, $fname = __METHOD__, $options = [] ) {
1518                 $table = $this->tableName( $table );
1519                 $opts = $this->makeUpdateOptions( $options );
1520                 $sql = "UPDATE $opts $table SET " . $this->makeList( $values, self::LIST_SET );
1521
1522                 if ( $conds !== [] && $conds !== '*' ) {
1523                         $sql .= " WHERE " . $this->makeList( $conds, self::LIST_AND );
1524                 }
1525
1526                 return $this->query( $sql, $fname );
1527         }
1528
1529         public function makeList( $a, $mode = self::LIST_COMMA ) {
1530                 if ( !is_array( $a ) ) {
1531                         throw new DBUnexpectedError( $this, __METHOD__ . ' called with incorrect parameters' );
1532                 }
1533
1534                 $first = true;
1535                 $list = '';
1536
1537                 foreach ( $a as $field => $value ) {
1538                         if ( !$first ) {
1539                                 if ( $mode == self::LIST_AND ) {
1540                                         $list .= ' AND ';
1541                                 } elseif ( $mode == self::LIST_OR ) {
1542                                         $list .= ' OR ';
1543                                 } else {
1544                                         $list .= ',';
1545                                 }
1546                         } else {
1547                                 $first = false;
1548                         }
1549
1550                         if ( ( $mode == self::LIST_AND || $mode == self::LIST_OR ) && is_numeric( $field ) ) {
1551                                 $list .= "($value)";
1552                         } elseif ( $mode == self::LIST_SET && is_numeric( $field ) ) {
1553                                 $list .= "$value";
1554                         } elseif (
1555                                 ( $mode == self::LIST_AND || $mode == self::LIST_OR ) && is_array( $value )
1556                         ) {
1557                                 // Remove null from array to be handled separately if found
1558                                 $includeNull = false;
1559                                 foreach ( array_keys( $value, null, true ) as $nullKey ) {
1560                                         $includeNull = true;
1561                                         unset( $value[$nullKey] );
1562                                 }
1563                                 if ( count( $value ) == 0 && !$includeNull ) {
1564                                         throw new InvalidArgumentException(
1565                                                 __METHOD__ . ": empty input for field $field" );
1566                                 } elseif ( count( $value ) == 0 ) {
1567                                         // only check if $field is null
1568                                         $list .= "$field IS NULL";
1569                                 } else {
1570                                         // IN clause contains at least one valid element
1571                                         if ( $includeNull ) {
1572                                                 // Group subconditions to ensure correct precedence
1573                                                 $list .= '(';
1574                                         }
1575                                         if ( count( $value ) == 1 ) {
1576                                                 // Special-case single values, as IN isn't terribly efficient
1577                                                 // Don't necessarily assume the single key is 0; we don't
1578                                                 // enforce linear numeric ordering on other arrays here.
1579                                                 $value = array_values( $value )[0];
1580                                                 $list .= $field . " = " . $this->addQuotes( $value );
1581                                         } else {
1582                                                 $list .= $field . " IN (" . $this->makeList( $value ) . ") ";
1583                                         }
1584                                         // if null present in array, append IS NULL
1585                                         if ( $includeNull ) {
1586                                                 $list .= " OR $field IS NULL)";
1587                                         }
1588                                 }
1589                         } elseif ( $value === null ) {
1590                                 if ( $mode == self::LIST_AND || $mode == self::LIST_OR ) {
1591                                         $list .= "$field IS ";
1592                                 } elseif ( $mode == self::LIST_SET ) {
1593                                         $list .= "$field = ";
1594                                 }
1595                                 $list .= 'NULL';
1596                         } else {
1597                                 if (
1598                                         $mode == self::LIST_AND || $mode == self::LIST_OR || $mode == self::LIST_SET
1599                                 ) {
1600                                         $list .= "$field = ";
1601                                 }
1602                                 $list .= $mode == self::LIST_NAMES ? $value : $this->addQuotes( $value );
1603                         }
1604                 }
1605
1606                 return $list;
1607         }
1608
1609         public function makeWhereFrom2d( $data, $baseKey, $subKey ) {
1610                 $conds = [];
1611
1612                 foreach ( $data as $base => $sub ) {
1613                         if ( count( $sub ) ) {
1614                                 $conds[] = $this->makeList(
1615                                         [ $baseKey => $base, $subKey => array_keys( $sub ) ],
1616                                         self::LIST_AND );
1617                         }
1618                 }
1619
1620                 if ( $conds ) {
1621                         return $this->makeList( $conds, self::LIST_OR );
1622                 } else {
1623                         // Nothing to search for...
1624                         return false;
1625                 }
1626         }
1627
1628         public function aggregateValue( $valuedata, $valuename = 'value' ) {
1629                 return $valuename;
1630         }
1631
1632         public function bitNot( $field ) {
1633                 return "(~$field)";
1634         }
1635
1636         public function bitAnd( $fieldLeft, $fieldRight ) {
1637                 return "($fieldLeft & $fieldRight)";
1638         }
1639
1640         public function bitOr( $fieldLeft, $fieldRight ) {
1641                 return "($fieldLeft | $fieldRight)";
1642         }
1643
1644         public function buildConcat( $stringList ) {
1645                 return 'CONCAT(' . implode( ',', $stringList ) . ')';
1646         }
1647
1648         public function buildGroupConcatField(
1649                 $delim, $table, $field, $conds = '', $join_conds = []
1650         ) {
1651                 $fld = "GROUP_CONCAT($field SEPARATOR " . $this->addQuotes( $delim ) . ')';
1652
1653                 return '(' . $this->selectSQLText( $table, $fld, $conds, null, [], $join_conds ) . ')';
1654         }
1655
1656         public function buildStringCast( $field ) {
1657                 return $field;
1658         }
1659
1660         public function selectDB( $db ) {
1661                 # Stub. Shouldn't cause serious problems if it's not overridden, but
1662                 # if your database engine supports a concept similar to MySQL's
1663                 # databases you may as well.
1664                 $this->mDBname = $db;
1665
1666                 return true;
1667         }
1668
1669         public function getDBname() {
1670                 return $this->mDBname;
1671         }
1672
1673         public function getServer() {
1674                 return $this->mServer;
1675         }
1676
1677         public function tableName( $name, $format = 'quoted' ) {
1678                 # Skip the entire process when we have a string quoted on both ends.
1679                 # Note that we check the end so that we will still quote any use of
1680                 # use of `database`.table. But won't break things if someone wants
1681                 # to query a database table with a dot in the name.
1682                 if ( $this->isQuotedIdentifier( $name ) ) {
1683                         return $name;
1684                 }
1685
1686                 # Lets test for any bits of text that should never show up in a table
1687                 # name. Basically anything like JOIN or ON which are actually part of
1688                 # SQL queries, but may end up inside of the table value to combine
1689                 # sql. Such as how the API is doing.
1690                 # Note that we use a whitespace test rather than a \b test to avoid
1691                 # any remote case where a word like on may be inside of a table name
1692                 # surrounded by symbols which may be considered word breaks.
1693                 if ( preg_match( '/(^|\s)(DISTINCT|JOIN|ON|AS)(\s|$)/i', $name ) !== 0 ) {
1694                         return $name;
1695                 }
1696
1697                 # Split database and table into proper variables.
1698                 # We reverse the explode so that database.table and table both output
1699                 # the correct table.
1700                 $dbDetails = explode( '.', $name, 3 );
1701                 if ( count( $dbDetails ) == 3 ) {
1702                         list( $database, $schema, $table ) = $dbDetails;
1703                         # We don't want any prefix added in this case
1704                         $prefix = '';
1705                 } elseif ( count( $dbDetails ) == 2 ) {
1706                         list( $database, $table ) = $dbDetails;
1707                         # We don't want any prefix added in this case
1708                         # In dbs that support it, $database may actually be the schema
1709                         # but that doesn't affect any of the functionality here
1710                         $prefix = '';
1711                         $schema = '';
1712                 } else {
1713                         list( $table ) = $dbDetails;
1714                         if ( isset( $this->tableAliases[$table] ) ) {
1715                                 $database = $this->tableAliases[$table]['dbname'];
1716                                 $schema = is_string( $this->tableAliases[$table]['schema'] )
1717                                         ? $this->tableAliases[$table]['schema']
1718                                         : $this->mSchema;
1719                                 $prefix = is_string( $this->tableAliases[$table]['prefix'] )
1720                                         ? $this->tableAliases[$table]['prefix']
1721                                         : $this->mTablePrefix;
1722                         } else {
1723                                 $database = '';
1724                                 $schema = $this->mSchema; # Default schema
1725                                 $prefix = $this->mTablePrefix; # Default prefix
1726                         }
1727                 }
1728
1729                 # Quote $table and apply the prefix if not quoted.
1730                 # $tableName might be empty if this is called from Database::replaceVars()
1731                 $tableName = "{$prefix}{$table}";
1732                 if ( $format == 'quoted'
1733                         && !$this->isQuotedIdentifier( $tableName ) && $tableName !== ''
1734                 ) {
1735                         $tableName = $this->addIdentifierQuotes( $tableName );
1736                 }
1737
1738                 # Quote $schema and merge it with the table name if needed
1739                 if ( strlen( $schema ) ) {
1740                         if ( $format == 'quoted' && !$this->isQuotedIdentifier( $schema ) ) {
1741                                 $schema = $this->addIdentifierQuotes( $schema );
1742                         }
1743                         $tableName = $schema . '.' . $tableName;
1744                 }
1745
1746                 # Quote $database and merge it with the table name if needed
1747                 if ( $database !== '' ) {
1748                         if ( $format == 'quoted' && !$this->isQuotedIdentifier( $database ) ) {
1749                                 $database = $this->addIdentifierQuotes( $database );
1750                         }
1751                         $tableName = $database . '.' . $tableName;
1752                 }
1753
1754                 return $tableName;
1755         }
1756
1757         public function tableNames() {
1758                 $inArray = func_get_args();
1759                 $retVal = [];
1760
1761                 foreach ( $inArray as $name ) {
1762                         $retVal[$name] = $this->tableName( $name );
1763                 }
1764
1765                 return $retVal;
1766         }
1767
1768         public function tableNamesN() {
1769                 $inArray = func_get_args();
1770                 $retVal = [];
1771
1772                 foreach ( $inArray as $name ) {
1773                         $retVal[] = $this->tableName( $name );
1774                 }
1775
1776                 return $retVal;
1777         }
1778
1779         /**
1780          * Get an aliased table name
1781          * e.g. tableName AS newTableName
1782          *
1783          * @param string $name Table name, see tableName()
1784          * @param string|bool $alias Alias (optional)
1785          * @return string SQL name for aliased table. Will not alias a table to its own name
1786          */
1787         protected function tableNameWithAlias( $name, $alias = false ) {
1788                 if ( !$alias || $alias == $name ) {
1789                         return $this->tableName( $name );
1790                 } else {
1791                         return $this->tableName( $name ) . ' ' . $this->addIdentifierQuotes( $alias );
1792                 }
1793         }
1794
1795         /**
1796          * Gets an array of aliased table names
1797          *
1798          * @param array $tables [ [alias] => table ]
1799          * @return string[] See tableNameWithAlias()
1800          */
1801         protected function tableNamesWithAlias( $tables ) {
1802                 $retval = [];
1803                 foreach ( $tables as $alias => $table ) {
1804                         if ( is_numeric( $alias ) ) {
1805                                 $alias = $table;
1806                         }
1807                         $retval[] = $this->tableNameWithAlias( $table, $alias );
1808                 }
1809
1810                 return $retval;
1811         }
1812
1813         /**
1814          * Get an aliased field name
1815          * e.g. fieldName AS newFieldName
1816          *
1817          * @param string $name Field name
1818          * @param string|bool $alias Alias (optional)
1819          * @return string SQL name for aliased field. Will not alias a field to its own name
1820          */
1821         protected function fieldNameWithAlias( $name, $alias = false ) {
1822                 if ( !$alias || (string)$alias === (string)$name ) {
1823                         return $name;
1824                 } else {
1825                         return $name . ' AS ' . $this->addIdentifierQuotes( $alias ); // PostgreSQL needs AS
1826                 }
1827         }
1828
1829         /**
1830          * Gets an array of aliased field names
1831          *
1832          * @param array $fields [ [alias] => field ]
1833          * @return string[] See fieldNameWithAlias()
1834          */
1835         protected function fieldNamesWithAlias( $fields ) {
1836                 $retval = [];
1837                 foreach ( $fields as $alias => $field ) {
1838                         if ( is_numeric( $alias ) ) {
1839                                 $alias = $field;
1840                         }
1841                         $retval[] = $this->fieldNameWithAlias( $field, $alias );
1842                 }
1843
1844                 return $retval;
1845         }
1846
1847         /**
1848          * Get the aliased table name clause for a FROM clause
1849          * which might have a JOIN and/or USE INDEX or IGNORE INDEX clause
1850          *
1851          * @param array $tables ( [alias] => table )
1852          * @param array $use_index Same as for select()
1853          * @param array $ignore_index Same as for select()
1854          * @param array $join_conds Same as for select()
1855          * @return string
1856          */
1857         protected function tableNamesWithIndexClauseOrJOIN(
1858                 $tables, $use_index = [], $ignore_index = [], $join_conds = []
1859         ) {
1860                 $ret = [];
1861                 $retJOIN = [];
1862                 $use_index = (array)$use_index;
1863                 $ignore_index = (array)$ignore_index;
1864                 $join_conds = (array)$join_conds;
1865
1866                 foreach ( $tables as $alias => $table ) {
1867                         if ( !is_string( $alias ) ) {
1868                                 // No alias? Set it equal to the table name
1869                                 $alias = $table;
1870                         }
1871                         // Is there a JOIN clause for this table?
1872                         if ( isset( $join_conds[$alias] ) ) {
1873                                 list( $joinType, $conds ) = $join_conds[$alias];
1874                                 $tableClause = $joinType;
1875                                 $tableClause .= ' ' . $this->tableNameWithAlias( $table, $alias );
1876                                 if ( isset( $use_index[$alias] ) ) { // has USE INDEX?
1877                                         $use = $this->useIndexClause( implode( ',', (array)$use_index[$alias] ) );
1878                                         if ( $use != '' ) {
1879                                                 $tableClause .= ' ' . $use;
1880                                         }
1881                                 }
1882                                 if ( isset( $ignore_index[$alias] ) ) { // has IGNORE INDEX?
1883                                         $ignore = $this->ignoreIndexClause(
1884                                                 implode( ',', (array)$ignore_index[$alias] ) );
1885                                         if ( $ignore != '' ) {
1886                                                 $tableClause .= ' ' . $ignore;
1887                                         }
1888                                 }
1889                                 $on = $this->makeList( (array)$conds, self::LIST_AND );
1890                                 if ( $on != '' ) {
1891                                         $tableClause .= ' ON (' . $on . ')';
1892                                 }
1893
1894                                 $retJOIN[] = $tableClause;
1895                         } elseif ( isset( $use_index[$alias] ) ) {
1896                                 // Is there an INDEX clause for this table?
1897                                 $tableClause = $this->tableNameWithAlias( $table, $alias );
1898                                 $tableClause .= ' ' . $this->useIndexClause(
1899                                                 implode( ',', (array)$use_index[$alias] )
1900                                         );
1901
1902                                 $ret[] = $tableClause;
1903                         } elseif ( isset( $ignore_index[$alias] ) ) {
1904                                 // Is there an INDEX clause for this table?
1905                                 $tableClause = $this->tableNameWithAlias( $table, $alias );
1906                                 $tableClause .= ' ' . $this->ignoreIndexClause(
1907                                                 implode( ',', (array)$ignore_index[$alias] )
1908                                         );
1909
1910                                 $ret[] = $tableClause;
1911                         } else {
1912                                 $tableClause = $this->tableNameWithAlias( $table, $alias );
1913
1914                                 $ret[] = $tableClause;
1915                         }
1916                 }
1917
1918                 // We can't separate explicit JOIN clauses with ',', use ' ' for those
1919                 $implicitJoins = !empty( $ret ) ? implode( ',', $ret ) : "";
1920                 $explicitJoins = !empty( $retJOIN ) ? implode( ' ', $retJOIN ) : "";
1921
1922                 // Compile our final table clause
1923                 return implode( ' ', [ $implicitJoins, $explicitJoins ] );
1924         }
1925
1926         /**
1927          * Get the name of an index in a given table.
1928          *
1929          * @param string $index
1930          * @return string
1931          */
1932         protected function indexName( $index ) {
1933                 return $index;
1934         }
1935
1936         public function addQuotes( $s ) {
1937                 if ( $s instanceof Blob ) {
1938                         $s = $s->fetch();
1939                 }
1940                 if ( $s === null ) {
1941                         return 'NULL';
1942                 } elseif ( is_bool( $s ) ) {
1943                         return (int)$s;
1944                 } else {
1945                         # This will also quote numeric values. This should be harmless,
1946                         # and protects against weird problems that occur when they really
1947                         # _are_ strings such as article titles and string->number->string
1948                         # conversion is not 1:1.
1949                         return "'" . $this->strencode( $s ) . "'";
1950                 }
1951         }
1952
1953         /**
1954          * Quotes an identifier using `backticks` or "double quotes" depending on the database type.
1955          * MySQL uses `backticks` while basically everything else uses double quotes.
1956          * Since MySQL is the odd one out here the double quotes are our generic
1957          * and we implement backticks in DatabaseMysql.
1958          *
1959          * @param string $s
1960          * @return string
1961          */
1962         public function addIdentifierQuotes( $s ) {
1963                 return '"' . str_replace( '"', '""', $s ) . '"';
1964         }
1965
1966         /**
1967          * Returns if the given identifier looks quoted or not according to
1968          * the database convention for quoting identifiers .
1969          *
1970          * @note Do not use this to determine if untrusted input is safe.
1971          *   A malicious user can trick this function.
1972          * @param string $name
1973          * @return bool
1974          */
1975         public function isQuotedIdentifier( $name ) {
1976                 return $name[0] == '"' && substr( $name, -1, 1 ) == '"';
1977         }
1978
1979         /**
1980          * @param string $s
1981          * @return string
1982          */
1983         protected function escapeLikeInternal( $s ) {
1984                 return addcslashes( $s, '\%_' );
1985         }
1986
1987         public function buildLike() {
1988                 $params = func_get_args();
1989
1990                 if ( count( $params ) > 0 && is_array( $params[0] ) ) {
1991                         $params = $params[0];
1992                 }
1993
1994                 $s = '';
1995
1996                 foreach ( $params as $value ) {
1997                         if ( $value instanceof LikeMatch ) {
1998                                 $s .= $value->toString();
1999                         } else {
2000                                 $s .= $this->escapeLikeInternal( $value );
2001                         }
2002                 }
2003
2004                 return " LIKE {$this->addQuotes( $s )} ";
2005         }
2006
2007         public function anyChar() {
2008                 return new LikeMatch( '_' );
2009         }
2010
2011         public function anyString() {
2012                 return new LikeMatch( '%' );
2013         }
2014
2015         public function nextSequenceValue( $seqName ) {
2016                 return null;
2017         }
2018
2019         /**
2020          * USE INDEX clause. Unlikely to be useful for anything but MySQL. This
2021          * is only needed because a) MySQL must be as efficient as possible due to
2022          * its use on Wikipedia, and b) MySQL 4.0 is kind of dumb sometimes about
2023          * which index to pick. Anyway, other databases might have different
2024          * indexes on a given table. So don't bother overriding this unless you're
2025          * MySQL.
2026          * @param string $index
2027          * @return string
2028          */
2029         public function useIndexClause( $index ) {
2030                 return '';
2031         }
2032
2033         /**
2034          * IGNORE INDEX clause. Unlikely to be useful for anything but MySQL. This
2035          * is only needed because a) MySQL must be as efficient as possible due to
2036          * its use on Wikipedia, and b) MySQL 4.0 is kind of dumb sometimes about
2037          * which index to pick. Anyway, other databases might have different
2038          * indexes on a given table. So don't bother overriding this unless you're
2039          * MySQL.
2040          * @param string $index
2041          * @return string
2042          */
2043         public function ignoreIndexClause( $index ) {
2044                 return '';
2045         }
2046
2047         public function replace( $table, $uniqueIndexes, $rows, $fname = __METHOD__ ) {
2048                 $quotedTable = $this->tableName( $table );
2049
2050                 if ( count( $rows ) == 0 ) {
2051                         return;
2052                 }
2053
2054                 # Single row case
2055                 if ( !is_array( reset( $rows ) ) ) {
2056                         $rows = [ $rows ];
2057                 }
2058
2059                 // @FXIME: this is not atomic, but a trx would break affectedRows()
2060                 foreach ( $rows as $row ) {
2061                         # Delete rows which collide
2062                         if ( $uniqueIndexes ) {
2063                                 $sql = "DELETE FROM $quotedTable WHERE ";
2064                                 $first = true;
2065                                 foreach ( $uniqueIndexes as $index ) {
2066                                         if ( $first ) {
2067                                                 $first = false;
2068                                                 $sql .= '( ';
2069                                         } else {
2070                                                 $sql .= ' ) OR ( ';
2071                                         }
2072                                         if ( is_array( $index ) ) {
2073                                                 $first2 = true;
2074                                                 foreach ( $index as $col ) {
2075                                                         if ( $first2 ) {
2076                                                                 $first2 = false;
2077                                                         } else {
2078                                                                 $sql .= ' AND ';
2079                                                         }
2080                                                         $sql .= $col . '=' . $this->addQuotes( $row[$col] );
2081                                                 }
2082                                         } else {
2083                                                 $sql .= $index . '=' . $this->addQuotes( $row[$index] );
2084                                         }
2085                                 }
2086                                 $sql .= ' )';
2087                                 $this->query( $sql, $fname );
2088                         }
2089
2090                         # Now insert the row
2091                         $this->insert( $table, $row, $fname );
2092                 }
2093         }
2094
2095         /**
2096          * REPLACE query wrapper for MySQL and SQLite, which have a native REPLACE
2097          * statement.
2098          *
2099          * @param string $table Table name
2100          * @param array|string $rows Row(s) to insert
2101          * @param string $fname Caller function name
2102          *
2103          * @return ResultWrapper
2104          */
2105         protected function nativeReplace( $table, $rows, $fname ) {
2106                 $table = $this->tableName( $table );
2107
2108                 # Single row case
2109                 if ( !is_array( reset( $rows ) ) ) {
2110                         $rows = [ $rows ];
2111                 }
2112
2113                 $sql = "REPLACE INTO $table (" . implode( ',', array_keys( $rows[0] ) ) . ') VALUES ';
2114                 $first = true;
2115
2116                 foreach ( $rows as $row ) {
2117                         if ( $first ) {
2118                                 $first = false;
2119                         } else {
2120                                 $sql .= ',';
2121                         }
2122
2123                         $sql .= '(' . $this->makeList( $row ) . ')';
2124                 }
2125
2126                 return $this->query( $sql, $fname );
2127         }
2128
2129         public function upsert( $table, array $rows, array $uniqueIndexes, array $set,
2130                 $fname = __METHOD__
2131         ) {
2132                 if ( !count( $rows ) ) {
2133                         return true; // nothing to do
2134                 }
2135
2136                 if ( !is_array( reset( $rows ) ) ) {
2137                         $rows = [ $rows ];
2138                 }
2139
2140                 if ( count( $uniqueIndexes ) ) {
2141                         $clauses = []; // list WHERE clauses that each identify a single row
2142                         foreach ( $rows as $row ) {
2143                                 foreach ( $uniqueIndexes as $index ) {
2144                                         $index = is_array( $index ) ? $index : [ $index ]; // columns
2145                                         $rowKey = []; // unique key to this row
2146                                         foreach ( $index as $column ) {
2147                                                 $rowKey[$column] = $row[$column];
2148                                         }
2149                                         $clauses[] = $this->makeList( $rowKey, self::LIST_AND );
2150                                 }
2151                         }
2152                         $where = [ $this->makeList( $clauses, self::LIST_OR ) ];
2153                 } else {
2154                         $where = false;
2155                 }
2156
2157                 $useTrx = !$this->mTrxLevel;
2158                 if ( $useTrx ) {
2159                         $this->begin( $fname, self::TRANSACTION_INTERNAL );
2160                 }
2161                 try {
2162                         # Update any existing conflicting row(s)
2163                         if ( $where !== false ) {
2164                                 $ok = $this->update( $table, $set, $where, $fname );
2165                         } else {
2166                                 $ok = true;
2167                         }
2168                         # Now insert any non-conflicting row(s)
2169                         $ok = $this->insert( $table, $rows, $fname, [ 'IGNORE' ] ) && $ok;
2170                 } catch ( Exception $e ) {
2171                         if ( $useTrx ) {
2172                                 $this->rollback( $fname, self::FLUSHING_INTERNAL );
2173                         }
2174                         throw $e;
2175                 }
2176                 if ( $useTrx ) {
2177                         $this->commit( $fname, self::FLUSHING_INTERNAL );
2178                 }
2179
2180                 return $ok;
2181         }
2182
2183         public function deleteJoin( $delTable, $joinTable, $delVar, $joinVar, $conds,
2184                 $fname = __METHOD__
2185         ) {
2186                 if ( !$conds ) {
2187                         throw new DBUnexpectedError( $this, __METHOD__ . ' called with empty $conds' );
2188                 }
2189
2190                 $delTable = $this->tableName( $delTable );
2191                 $joinTable = $this->tableName( $joinTable );
2192                 $sql = "DELETE FROM $delTable WHERE $delVar IN (SELECT $joinVar FROM $joinTable ";
2193                 if ( $conds != '*' ) {
2194                         $sql .= 'WHERE ' . $this->makeList( $conds, self::LIST_AND );
2195                 }
2196                 $sql .= ')';
2197
2198                 $this->query( $sql, $fname );
2199         }
2200
2201         public function textFieldSize( $table, $field ) {
2202                 $table = $this->tableName( $table );
2203                 $sql = "SHOW COLUMNS FROM $table LIKE \"$field\";";
2204                 $res = $this->query( $sql, __METHOD__ );
2205                 $row = $this->fetchObject( $res );
2206
2207                 $m = [];
2208
2209                 if ( preg_match( '/\((.*)\)/', $row->Type, $m ) ) {
2210                         $size = $m[1];
2211                 } else {
2212                         $size = -1;
2213                 }
2214
2215                 return $size;
2216         }
2217
2218         public function delete( $table, $conds, $fname = __METHOD__ ) {
2219                 if ( !$conds ) {
2220                         throw new DBUnexpectedError( $this, __METHOD__ . ' called with no conditions' );
2221                 }
2222
2223                 $table = $this->tableName( $table );
2224                 $sql = "DELETE FROM $table";
2225
2226                 if ( $conds != '*' ) {
2227                         if ( is_array( $conds ) ) {
2228                                 $conds = $this->makeList( $conds, self::LIST_AND );
2229                         }
2230                         $sql .= ' WHERE ' . $conds;
2231                 }
2232
2233                 return $this->query( $sql, $fname );
2234         }
2235
2236         public function insertSelect(
2237                 $destTable, $srcTable, $varMap, $conds,
2238                 $fname = __METHOD__, $insertOptions = [], $selectOptions = []
2239         ) {
2240                 if ( $this->cliMode ) {
2241                         // For massive migrations with downtime, we don't want to select everything
2242                         // into memory and OOM, so do all this native on the server side if possible.
2243                         return $this->nativeInsertSelect(
2244                                 $destTable,
2245                                 $srcTable,
2246                                 $varMap,
2247                                 $conds,
2248                                 $fname,
2249                                 $insertOptions,
2250                                 $selectOptions
2251                         );
2252                 }
2253
2254                 // For web requests, do a locking SELECT and then INSERT. This puts the SELECT burden
2255                 // on only the master (without needing row-based-replication). It also makes it easy to
2256                 // know how big the INSERT is going to be.
2257                 $fields = [];
2258                 foreach ( $varMap as $dstColumn => $sourceColumnOrSql ) {
2259                         $fields[] = $this->fieldNameWithAlias( $sourceColumnOrSql, $dstColumn );
2260                 }
2261                 $selectOptions[] = 'FOR UPDATE';
2262                 $res = $this->select( $srcTable, implode( ',', $fields ), $conds, $fname, $selectOptions );
2263                 if ( !$res ) {
2264                         return false;
2265                 }
2266
2267                 $rows = [];
2268                 foreach ( $res as $row ) {
2269                         $rows[] = (array)$row;
2270                 }
2271
2272                 return $this->insert( $destTable, $rows, $fname, $insertOptions );
2273         }
2274
2275         protected function nativeInsertSelect( $destTable, $srcTable, $varMap, $conds,
2276                 $fname = __METHOD__,
2277                 $insertOptions = [], $selectOptions = []
2278         ) {
2279                 $destTable = $this->tableName( $destTable );
2280
2281                 if ( !is_array( $insertOptions ) ) {
2282                         $insertOptions = [ $insertOptions ];
2283                 }
2284
2285                 $insertOptions = $this->makeInsertOptions( $insertOptions );
2286
2287                 if ( !is_array( $selectOptions ) ) {
2288                         $selectOptions = [ $selectOptions ];
2289                 }
2290
2291                 list( $startOpts, $useIndex, $tailOpts, $ignoreIndex ) = $this->makeSelectOptions(
2292                         $selectOptions );
2293
2294                 if ( is_array( $srcTable ) ) {
2295                         $srcTable = implode( ',', array_map( [ &$this, 'tableName' ], $srcTable ) );
2296                 } else {
2297                         $srcTable = $this->tableName( $srcTable );
2298                 }
2299
2300                 $sql = "INSERT $insertOptions" .
2301                         " INTO $destTable (" . implode( ',', array_keys( $varMap ) ) . ')' .
2302                         " SELECT $startOpts " . implode( ',', $varMap ) .
2303                         " FROM $srcTable $useIndex $ignoreIndex ";
2304
2305                 if ( $conds != '*' ) {
2306                         if ( is_array( $conds ) ) {
2307                                 $conds = $this->makeList( $conds, self::LIST_AND );
2308                         }
2309                         $sql .= " WHERE $conds";
2310                 }
2311
2312                 $sql .= " $tailOpts";
2313
2314                 return $this->query( $sql, $fname );
2315         }
2316
2317         /**
2318          * Construct a LIMIT query with optional offset. This is used for query
2319          * pages. The SQL should be adjusted so that only the first $limit rows
2320          * are returned. If $offset is provided as well, then the first $offset
2321          * rows should be discarded, and the next $limit rows should be returned.
2322          * If the result of the query is not ordered, then the rows to be returned
2323          * are theoretically arbitrary.
2324          *
2325          * $sql is expected to be a SELECT, if that makes a difference.
2326          *
2327          * The version provided by default works in MySQL and SQLite. It will very
2328          * likely need to be overridden for most other DBMSes.
2329          *
2330          * @param string $sql SQL query we will append the limit too
2331          * @param int $limit The SQL limit
2332          * @param int|bool $offset The SQL offset (default false)
2333          * @throws DBUnexpectedError
2334          * @return string
2335          */
2336         public function limitResult( $sql, $limit, $offset = false ) {
2337                 if ( !is_numeric( $limit ) ) {
2338                         throw new DBUnexpectedError( $this,
2339                                 "Invalid non-numeric limit passed to limitResult()\n" );
2340                 }
2341
2342                 return "$sql LIMIT "
2343                 . ( ( is_numeric( $offset ) && $offset != 0 ) ? "{$offset}," : "" )
2344                 . "{$limit} ";
2345         }
2346
2347         public function unionSupportsOrderAndLimit() {
2348                 return true; // True for almost every DB supported
2349         }
2350
2351         public function unionQueries( $sqls, $all ) {
2352                 $glue = $all ? ') UNION ALL (' : ') UNION (';
2353
2354                 return '(' . implode( $glue, $sqls ) . ')';
2355         }
2356
2357         public function conditional( $cond, $trueVal, $falseVal ) {
2358                 if ( is_array( $cond ) ) {
2359                         $cond = $this->makeList( $cond, self::LIST_AND );
2360                 }
2361
2362                 return " (CASE WHEN $cond THEN $trueVal ELSE $falseVal END) ";
2363         }
2364
2365         public function strreplace( $orig, $old, $new ) {
2366                 return "REPLACE({$orig}, {$old}, {$new})";
2367         }
2368
2369         public function getServerUptime() {
2370                 return 0;
2371         }
2372
2373         public function wasDeadlock() {
2374                 return false;
2375         }
2376
2377         public function wasLockTimeout() {
2378                 return false;
2379         }
2380
2381         public function wasErrorReissuable() {
2382                 return false;
2383         }
2384
2385         public function wasReadOnlyError() {
2386                 return false;
2387         }
2388
2389         /**
2390          * Do not use this method outside of Database/DBError classes
2391          *
2392          * @param integer|string $errno
2393          * @return bool Whether the given query error was a connection drop
2394          */
2395         public function wasConnectionError( $errno ) {
2396                 return false;
2397         }
2398
2399         public function deadlockLoop() {
2400                 $args = func_get_args();
2401                 $function = array_shift( $args );
2402                 $tries = self::DEADLOCK_TRIES;
2403
2404                 $this->begin( __METHOD__ );
2405
2406                 $retVal = null;
2407                 /** @var Exception $e */
2408                 $e = null;
2409                 do {
2410                         try {
2411                                 $retVal = call_user_func_array( $function, $args );
2412                                 break;
2413                         } catch ( DBQueryError $e ) {
2414                                 if ( $this->wasDeadlock() ) {
2415                                         // Retry after a randomized delay
2416                                         usleep( mt_rand( self::DEADLOCK_DELAY_MIN, self::DEADLOCK_DELAY_MAX ) );
2417                                 } else {
2418                                         // Throw the error back up
2419                                         throw $e;
2420                                 }
2421                         }
2422                 } while ( --$tries > 0 );
2423
2424                 if ( $tries <= 0 ) {
2425                         // Too many deadlocks; give up
2426                         $this->rollback( __METHOD__ );
2427                         throw $e;
2428                 } else {
2429                         $this->commit( __METHOD__ );
2430
2431                         return $retVal;
2432                 }
2433         }
2434
2435         public function masterPosWait( DBMasterPos $pos, $timeout ) {
2436                 # Real waits are implemented in the subclass.
2437                 return 0;
2438         }
2439
2440         public function getReplicaPos() {
2441                 # Stub
2442                 return false;
2443         }
2444
2445         public function getMasterPos() {
2446                 # Stub
2447                 return false;
2448         }
2449
2450         public function serverIsReadOnly() {
2451                 return false;
2452         }
2453
2454         final public function onTransactionResolution( callable $callback, $fname = __METHOD__ ) {
2455                 if ( !$this->mTrxLevel ) {
2456                         throw new DBUnexpectedError( $this, "No transaction is active." );
2457                 }
2458                 $this->mTrxEndCallbacks[] = [ $callback, $fname ];
2459         }
2460
2461         final public function onTransactionIdle( callable $callback, $fname = __METHOD__ ) {
2462                 $this->mTrxIdleCallbacks[] = [ $callback, $fname ];
2463                 if ( !$this->mTrxLevel ) {
2464                         $this->runOnTransactionIdleCallbacks( self::TRIGGER_IDLE );
2465                 }
2466         }
2467
2468         final public function onTransactionPreCommitOrIdle( callable $callback, $fname = __METHOD__ ) {
2469                 if ( $this->mTrxLevel ) {
2470                         $this->mTrxPreCommitCallbacks[] = [ $callback, $fname ];
2471                 } else {
2472                         // If no transaction is active, then make one for this callback
2473                         $this->startAtomic( __METHOD__ );
2474                         try {
2475                                 call_user_func( $callback );
2476                                 $this->endAtomic( __METHOD__ );
2477                         } catch ( Exception $e ) {
2478                                 $this->rollback( __METHOD__, self::FLUSHING_INTERNAL );
2479                                 throw $e;
2480                         }
2481                 }
2482         }
2483
2484         final public function setTransactionListener( $name, callable $callback = null ) {
2485                 if ( $callback ) {
2486                         $this->mTrxRecurringCallbacks[$name] = $callback;
2487                 } else {
2488                         unset( $this->mTrxRecurringCallbacks[$name] );
2489                 }
2490         }
2491
2492         /**
2493          * Whether to disable running of post-COMMIT/ROLLBACK callbacks
2494          *
2495          * This method should not be used outside of Database/LoadBalancer
2496          *
2497          * @param bool $suppress
2498          * @since 1.28
2499          */
2500         final public function setTrxEndCallbackSuppression( $suppress ) {
2501                 $this->mTrxEndCallbacksSuppressed = $suppress;
2502         }
2503
2504         /**
2505          * Actually run and consume any "on transaction idle/resolution" callbacks.
2506          *
2507          * This method should not be used outside of Database/LoadBalancer
2508          *
2509          * @param integer $trigger IDatabase::TRIGGER_* constant
2510          * @since 1.20
2511          * @throws Exception
2512          */
2513         public function runOnTransactionIdleCallbacks( $trigger ) {
2514                 if ( $this->mTrxEndCallbacksSuppressed ) {
2515                         return;
2516                 }
2517
2518                 $autoTrx = $this->getFlag( self::DBO_TRX ); // automatic begin() enabled?
2519                 /** @var Exception $e */
2520                 $e = null; // first exception
2521                 do { // callbacks may add callbacks :)
2522                         $callbacks = array_merge(
2523                                 $this->mTrxIdleCallbacks,
2524                                 $this->mTrxEndCallbacks // include "transaction resolution" callbacks
2525                         );
2526                         $this->mTrxIdleCallbacks = []; // consumed (and recursion guard)
2527                         $this->mTrxEndCallbacks = []; // consumed (recursion guard)
2528                         foreach ( $callbacks as $callback ) {
2529                                 try {
2530                                         list( $phpCallback ) = $callback;
2531                                         $this->clearFlag( self::DBO_TRX ); // make each query its own transaction
2532                                         call_user_func_array( $phpCallback, [ $trigger ] );
2533                                         if ( $autoTrx ) {
2534                                                 $this->setFlag( self::DBO_TRX ); // restore automatic begin()
2535                                         } else {
2536                                                 $this->clearFlag( self::DBO_TRX ); // restore auto-commit
2537                                         }
2538                                 } catch ( Exception $ex ) {
2539                                         call_user_func( $this->errorLogger, $ex );
2540                                         $e = $e ?: $ex;
2541                                         // Some callbacks may use startAtomic/endAtomic, so make sure
2542                                         // their transactions are ended so other callbacks don't fail
2543                                         if ( $this->trxLevel() ) {
2544                                                 $this->rollback( __METHOD__, self::FLUSHING_INTERNAL );
2545                                         }
2546                                 }
2547                         }
2548                 } while ( count( $this->mTrxIdleCallbacks ) );
2549
2550                 if ( $e instanceof Exception ) {
2551                         throw $e; // re-throw any first exception
2552                 }
2553         }
2554
2555         /**
2556          * Actually run and consume any "on transaction pre-commit" callbacks.
2557          *
2558          * This method should not be used outside of Database/LoadBalancer
2559          *
2560          * @since 1.22
2561          * @throws Exception
2562          */
2563         public function runOnTransactionPreCommitCallbacks() {
2564                 $e = null; // first exception
2565                 do { // callbacks may add callbacks :)
2566                         $callbacks = $this->mTrxPreCommitCallbacks;
2567                         $this->mTrxPreCommitCallbacks = []; // consumed (and recursion guard)
2568                         foreach ( $callbacks as $callback ) {
2569                                 try {
2570                                         list( $phpCallback ) = $callback;
2571                                         call_user_func( $phpCallback );
2572                                 } catch ( Exception $ex ) {
2573                                         call_user_func( $this->errorLogger, $ex );
2574                                         $e = $e ?: $ex;
2575                                 }
2576                         }
2577                 } while ( count( $this->mTrxPreCommitCallbacks ) );
2578
2579                 if ( $e instanceof Exception ) {
2580                         throw $e; // re-throw any first exception
2581                 }
2582         }
2583
2584         /**
2585          * Actually run any "transaction listener" callbacks.
2586          *
2587          * This method should not be used outside of Database/LoadBalancer
2588          *
2589          * @param integer $trigger IDatabase::TRIGGER_* constant
2590          * @throws Exception
2591          * @since 1.20
2592          */
2593         public function runTransactionListenerCallbacks( $trigger ) {
2594                 if ( $this->mTrxEndCallbacksSuppressed ) {
2595                         return;
2596                 }
2597
2598                 /** @var Exception $e */
2599                 $e = null; // first exception
2600
2601                 foreach ( $this->mTrxRecurringCallbacks as $phpCallback ) {
2602                         try {
2603                                 $phpCallback( $trigger, $this );
2604                         } catch ( Exception $ex ) {
2605                                 call_user_func( $this->errorLogger, $ex );
2606                                 $e = $e ?: $ex;
2607                         }
2608                 }
2609
2610                 if ( $e instanceof Exception ) {
2611                         throw $e; // re-throw any first exception
2612                 }
2613         }
2614
2615         final public function startAtomic( $fname = __METHOD__ ) {
2616                 if ( !$this->mTrxLevel ) {
2617                         $this->begin( $fname, self::TRANSACTION_INTERNAL );
2618                         // If DBO_TRX is set, a series of startAtomic/endAtomic pairs will result
2619                         // in all changes being in one transaction to keep requests transactional.
2620                         if ( !$this->getFlag( self::DBO_TRX ) ) {
2621                                 $this->mTrxAutomaticAtomic = true;
2622                         }
2623                 }
2624
2625                 $this->mTrxAtomicLevels[] = $fname;
2626         }
2627
2628         final public function endAtomic( $fname = __METHOD__ ) {
2629                 if ( !$this->mTrxLevel ) {
2630                         throw new DBUnexpectedError( $this, "No atomic transaction is open (got $fname)." );
2631                 }
2632                 if ( !$this->mTrxAtomicLevels ||
2633                         array_pop( $this->mTrxAtomicLevels ) !== $fname
2634                 ) {
2635                         throw new DBUnexpectedError( $this, "Invalid atomic section ended (got $fname)." );
2636                 }
2637
2638                 if ( !$this->mTrxAtomicLevels && $this->mTrxAutomaticAtomic ) {
2639                         $this->commit( $fname, self::FLUSHING_INTERNAL );
2640                 }
2641         }
2642
2643         final public function doAtomicSection( $fname, callable $callback ) {
2644                 $this->startAtomic( $fname );
2645                 try {
2646                         $res = call_user_func_array( $callback, [ $this, $fname ] );
2647                 } catch ( Exception $e ) {
2648                         $this->rollback( $fname, self::FLUSHING_INTERNAL );
2649                         throw $e;
2650                 }
2651                 $this->endAtomic( $fname );
2652
2653                 return $res;
2654         }
2655
2656         final public function begin( $fname = __METHOD__, $mode = self::TRANSACTION_EXPLICIT ) {
2657                 // Protect against mismatched atomic section, transaction nesting, and snapshot loss
2658                 if ( $this->mTrxLevel ) {
2659                         if ( $this->mTrxAtomicLevels ) {
2660                                 $levels = implode( ', ', $this->mTrxAtomicLevels );
2661                                 $msg = "$fname: Got explicit BEGIN while atomic section(s) $levels are open.";
2662                                 throw new DBUnexpectedError( $this, $msg );
2663                         } elseif ( !$this->mTrxAutomatic ) {
2664                                 $msg = "$fname: Explicit transaction already active (from {$this->mTrxFname}).";
2665                                 throw new DBUnexpectedError( $this, $msg );
2666                         } else {
2667                                 // @TODO: make this an exception at some point
2668                                 $msg = "$fname: Implicit transaction already active (from {$this->mTrxFname}).";
2669                                 $this->queryLogger->error( $msg );
2670                                 return; // join the main transaction set
2671                         }
2672                 } elseif ( $this->getFlag( self::DBO_TRX ) && $mode !== self::TRANSACTION_INTERNAL ) {
2673                         // @TODO: make this an exception at some point
2674                         $msg = "$fname: Implicit transaction expected (DBO_TRX set).";
2675                         $this->queryLogger->error( $msg );
2676                         return; // let any writes be in the main transaction
2677                 }
2678
2679                 // Avoid fatals if close() was called
2680                 $this->assertOpen();
2681
2682                 $this->doBegin( $fname );
2683                 $this->mTrxTimestamp = microtime( true );
2684                 $this->mTrxFname = $fname;
2685                 $this->mTrxDoneWrites = false;
2686                 $this->mTrxAutomaticAtomic = false;
2687                 $this->mTrxAtomicLevels = [];
2688                 $this->mTrxShortId = sprintf( '%06x', mt_rand( 0, 0xffffff ) );
2689                 $this->mTrxWriteDuration = 0.0;
2690                 $this->mTrxWriteQueryCount = 0;
2691                 $this->mTrxWriteAdjDuration = 0.0;
2692                 $this->mTrxWriteAdjQueryCount = 0;
2693                 $this->mTrxWriteCallers = [];
2694                 // First SELECT after BEGIN will establish the snapshot in REPEATABLE-READ.
2695                 // Get an estimate of the replica DB lag before then, treating estimate staleness
2696                 // as lag itself just to be safe
2697                 $status = $this->getApproximateLagStatus();
2698                 $this->mTrxReplicaLag = $status['lag'] + ( microtime( true ) - $status['since'] );
2699                 // T147697: make explicitTrxActive() return true until begin() finishes. This way, no
2700                 // caller will think its OK to muck around with the transaction just because startAtomic()
2701                 // has not yet completed (e.g. setting mTrxAtomicLevels).
2702                 $this->mTrxAutomatic = ( $mode === self::TRANSACTION_INTERNAL );
2703         }
2704
2705         /**
2706          * Issues the BEGIN command to the database server.
2707          *
2708          * @see Database::begin()
2709          * @param string $fname
2710          */
2711         protected function doBegin( $fname ) {
2712                 $this->query( 'BEGIN', $fname );
2713                 $this->mTrxLevel = 1;
2714         }
2715
2716         final public function commit( $fname = __METHOD__, $flush = '' ) {
2717                 if ( $this->mTrxLevel && $this->mTrxAtomicLevels ) {
2718                         // There are still atomic sections open. This cannot be ignored
2719                         $levels = implode( ', ', $this->mTrxAtomicLevels );
2720                         throw new DBUnexpectedError(
2721                                 $this,
2722                                 "$fname: Got COMMIT while atomic sections $levels are still open."
2723                         );
2724                 }
2725
2726                 if ( $flush === self::FLUSHING_INTERNAL || $flush === self::FLUSHING_ALL_PEERS ) {
2727                         if ( !$this->mTrxLevel ) {
2728                                 return; // nothing to do
2729                         } elseif ( !$this->mTrxAutomatic ) {
2730                                 throw new DBUnexpectedError(
2731                                         $this,
2732                                         "$fname: Flushing an explicit transaction, getting out of sync."
2733                                 );
2734                         }
2735                 } else {
2736                         if ( !$this->mTrxLevel ) {
2737                                 $this->queryLogger->error(
2738                                         "$fname: No transaction to commit, something got out of sync." );
2739                                 return; // nothing to do
2740                         } elseif ( $this->mTrxAutomatic ) {
2741                                 // @TODO: make this an exception at some point
2742                                 $msg = "$fname: Explicit commit of implicit transaction.";
2743                                 $this->queryLogger->error( $msg );
2744                                 return; // wait for the main transaction set commit round
2745                         }
2746                 }
2747
2748                 // Avoid fatals if close() was called
2749                 $this->assertOpen();
2750
2751                 $this->runOnTransactionPreCommitCallbacks();
2752                 $writeTime = $this->pendingWriteQueryDuration( self::ESTIMATE_DB_APPLY );
2753                 $this->doCommit( $fname );
2754                 if ( $this->mTrxDoneWrites ) {
2755                         $this->mLastWriteTime = microtime( true );
2756                         $this->trxProfiler->transactionWritingOut(
2757                                 $this->mServer, $this->mDBname, $this->mTrxShortId, $writeTime );
2758                 }
2759
2760                 $this->runOnTransactionIdleCallbacks( self::TRIGGER_COMMIT );
2761                 $this->runTransactionListenerCallbacks( self::TRIGGER_COMMIT );
2762         }
2763
2764         /**
2765          * Issues the COMMIT command to the database server.
2766          *
2767          * @see Database::commit()
2768          * @param string $fname
2769          */
2770         protected function doCommit( $fname ) {
2771                 if ( $this->mTrxLevel ) {
2772                         $this->query( 'COMMIT', $fname );
2773                         $this->mTrxLevel = 0;
2774                 }
2775         }
2776
2777         final public function rollback( $fname = __METHOD__, $flush = '' ) {
2778                 if ( $flush === self::FLUSHING_INTERNAL || $flush === self::FLUSHING_ALL_PEERS ) {
2779                         if ( !$this->mTrxLevel ) {
2780                                 return; // nothing to do
2781                         }
2782                 } else {
2783                         if ( !$this->mTrxLevel ) {
2784                                 $this->queryLogger->error(
2785                                         "$fname: No transaction to rollback, something got out of sync." );
2786                                 return; // nothing to do
2787                         } elseif ( $this->getFlag( self::DBO_TRX ) ) {
2788                                 throw new DBUnexpectedError(
2789                                         $this,
2790                                         "$fname: Expected mass rollback of all peer databases (DBO_TRX set)."
2791                                 );
2792                         }
2793                 }
2794
2795                 // Avoid fatals if close() was called
2796                 $this->assertOpen();
2797
2798                 $this->doRollback( $fname );
2799                 $this->mTrxAtomicLevels = [];
2800                 if ( $this->mTrxDoneWrites ) {
2801                         $this->trxProfiler->transactionWritingOut(
2802                                 $this->mServer, $this->mDBname, $this->mTrxShortId );
2803                 }
2804
2805                 $this->mTrxIdleCallbacks = []; // clear
2806                 $this->mTrxPreCommitCallbacks = []; // clear
2807                 $this->runOnTransactionIdleCallbacks( self::TRIGGER_ROLLBACK );
2808                 $this->runTransactionListenerCallbacks( self::TRIGGER_ROLLBACK );
2809         }
2810
2811         /**
2812          * Issues the ROLLBACK command to the database server.
2813          *
2814          * @see Database::rollback()
2815          * @param string $fname
2816          */
2817         protected function doRollback( $fname ) {
2818                 if ( $this->mTrxLevel ) {
2819                         # Disconnects cause rollback anyway, so ignore those errors
2820                         $ignoreErrors = true;
2821                         $this->query( 'ROLLBACK', $fname, $ignoreErrors );
2822                         $this->mTrxLevel = 0;
2823                 }
2824         }
2825
2826         public function flushSnapshot( $fname = __METHOD__ ) {
2827                 if ( $this->writesOrCallbacksPending() || $this->explicitTrxActive() ) {
2828                         // This only flushes transactions to clear snapshots, not to write data
2829                         $fnames = implode( ', ', $this->pendingWriteAndCallbackCallers() );
2830                         throw new DBUnexpectedError(
2831                                 $this,
2832                                 "$fname: Cannot COMMIT to clear snapshot because writes are pending ($fnames)."
2833                         );
2834                 }
2835
2836                 $this->commit( $fname, self::FLUSHING_INTERNAL );
2837         }
2838
2839         public function explicitTrxActive() {
2840                 return $this->mTrxLevel && ( $this->mTrxAtomicLevels || !$this->mTrxAutomatic );
2841         }
2842
2843         /**
2844          * Creates a new table with structure copied from existing table
2845          * Note that unlike most database abstraction functions, this function does not
2846          * automatically append database prefix, because it works at a lower
2847          * abstraction level.
2848          * The table names passed to this function shall not be quoted (this
2849          * function calls addIdentifierQuotes when needed).
2850          *
2851          * @param string $oldName Name of table whose structure should be copied
2852          * @param string $newName Name of table to be created
2853          * @param bool $temporary Whether the new table should be temporary
2854          * @param string $fname Calling function name
2855          * @throws RuntimeException
2856          * @return bool True if operation was successful
2857          */
2858         public function duplicateTableStructure( $oldName, $newName, $temporary = false,
2859                 $fname = __METHOD__
2860         ) {
2861                 throw new RuntimeException( __METHOD__ . ' is not implemented in descendant class' );
2862         }
2863
2864         public function listTables( $prefix = null, $fname = __METHOD__ ) {
2865                 throw new RuntimeException( __METHOD__ . ' is not implemented in descendant class' );
2866         }
2867
2868         public function listViews( $prefix = null, $fname = __METHOD__ ) {
2869                 throw new RuntimeException( __METHOD__ . ' is not implemented in descendant class' );
2870         }
2871
2872         public function timestamp( $ts = 0 ) {
2873                 $t = new ConvertibleTimestamp( $ts );
2874                 // Let errors bubble up to avoid putting garbage in the DB
2875                 return $t->getTimestamp( TS_MW );
2876         }
2877
2878         public function timestampOrNull( $ts = null ) {
2879                 if ( is_null( $ts ) ) {
2880                         return null;
2881                 } else {
2882                         return $this->timestamp( $ts );
2883                 }
2884         }
2885
2886         /**
2887          * Take the result from a query, and wrap it in a ResultWrapper if
2888          * necessary. Boolean values are passed through as is, to indicate success
2889          * of write queries or failure.
2890          *
2891          * Once upon a time, Database::query() returned a bare MySQL result
2892          * resource, and it was necessary to call this function to convert it to
2893          * a wrapper. Nowadays, raw database objects are never exposed to external
2894          * callers, so this is unnecessary in external code.
2895          *
2896          * @param bool|ResultWrapper|resource|object $result
2897          * @return bool|ResultWrapper
2898          */
2899         protected function resultObject( $result ) {
2900                 if ( !$result ) {
2901                         return false;
2902                 } elseif ( $result instanceof ResultWrapper ) {
2903                         return $result;
2904                 } elseif ( $result === true ) {
2905                         // Successful write query
2906                         return $result;
2907                 } else {
2908                         return new ResultWrapper( $this, $result );
2909                 }
2910         }
2911
2912         public function ping( &$rtt = null ) {
2913                 // Avoid hitting the server if it was hit recently
2914                 if ( $this->isOpen() && ( microtime( true ) - $this->lastPing ) < self::PING_TTL ) {
2915                         if ( !func_num_args() || $this->mRTTEstimate > 0 ) {
2916                                 $rtt = $this->mRTTEstimate;
2917                                 return true; // don't care about $rtt
2918                         }
2919                 }
2920
2921                 // This will reconnect if possible or return false if not
2922                 $this->clearFlag( self::DBO_TRX, self::REMEMBER_PRIOR );
2923                 $ok = ( $this->query( self::PING_QUERY, __METHOD__, true ) !== false );
2924                 $this->restoreFlags( self::RESTORE_PRIOR );
2925
2926                 if ( $ok ) {
2927                         $rtt = $this->mRTTEstimate;
2928                 }
2929
2930                 return $ok;
2931         }
2932
2933         /**
2934          * @return bool
2935          */
2936         protected function reconnect() {
2937                 $this->closeConnection();
2938                 $this->mOpened = false;
2939                 $this->mConn = false;
2940                 try {
2941                         $this->open( $this->mServer, $this->mUser, $this->mPassword, $this->mDBname );
2942                         $this->lastPing = microtime( true );
2943                         $ok = true;
2944                 } catch ( DBConnectionError $e ) {
2945                         $ok = false;
2946                 }
2947
2948                 return $ok;
2949         }
2950
2951         public function getSessionLagStatus() {
2952                 return $this->getTransactionLagStatus() ?: $this->getApproximateLagStatus();
2953         }
2954
2955         /**
2956          * Get the replica DB lag when the current transaction started
2957          *
2958          * This is useful when transactions might use snapshot isolation
2959          * (e.g. REPEATABLE-READ in innodb), so the "real" lag of that data
2960          * is this lag plus transaction duration. If they don't, it is still
2961          * safe to be pessimistic. This returns null if there is no transaction.
2962          *
2963          * @return array|null ('lag': seconds or false on error, 'since': UNIX timestamp of BEGIN)
2964          * @since 1.27
2965          */
2966         protected function getTransactionLagStatus() {
2967                 return $this->mTrxLevel
2968                         ? [ 'lag' => $this->mTrxReplicaLag, 'since' => $this->trxTimestamp() ]
2969                         : null;
2970         }
2971
2972         /**
2973          * Get a replica DB lag estimate for this server
2974          *
2975          * @return array ('lag': seconds or false on error, 'since': UNIX timestamp of estimate)
2976          * @since 1.27
2977          */
2978         protected function getApproximateLagStatus() {
2979                 return [
2980                         'lag'   => $this->getLBInfo( 'replica' ) ? $this->getLag() : 0,
2981                         'since' => microtime( true )
2982                 ];
2983         }
2984
2985         /**
2986          * Merge the result of getSessionLagStatus() for several DBs
2987          * using the most pessimistic values to estimate the lag of
2988          * any data derived from them in combination
2989          *
2990          * This is information is useful for caching modules
2991          *
2992          * @see WANObjectCache::set()
2993          * @see WANObjectCache::getWithSetCallback()
2994          *
2995          * @param IDatabase $db1
2996          * @param IDatabase ...
2997          * @return array Map of values:
2998          *   - lag: highest lag of any of the DBs or false on error (e.g. replication stopped)
2999          *   - since: oldest UNIX timestamp of any of the DB lag estimates
3000          *   - pending: whether any of the DBs have uncommitted changes
3001          * @since 1.27
3002          */
3003         public static function getCacheSetOptions( IDatabase $db1 ) {
3004                 $res = [ 'lag' => 0, 'since' => INF, 'pending' => false ];
3005                 foreach ( func_get_args() as $db ) {
3006                         /** @var IDatabase $db */
3007                         $status = $db->getSessionLagStatus();
3008                         if ( $status['lag'] === false ) {
3009                                 $res['lag'] = false;
3010                         } elseif ( $res['lag'] !== false ) {
3011                                 $res['lag'] = max( $res['lag'], $status['lag'] );
3012                         }
3013                         $res['since'] = min( $res['since'], $status['since'] );
3014                         $res['pending'] = $res['pending'] ?: $db->writesPending();
3015                 }
3016
3017                 return $res;
3018         }
3019
3020         public function getLag() {
3021                 return 0;
3022         }
3023
3024         public function maxListLen() {
3025                 return 0;
3026         }
3027
3028         public function encodeBlob( $b ) {
3029                 return $b;
3030         }
3031
3032         public function decodeBlob( $b ) {
3033                 if ( $b instanceof Blob ) {
3034                         $b = $b->fetch();
3035                 }
3036                 return $b;
3037         }
3038
3039         public function setSessionOptions( array $options ) {
3040         }
3041
3042         public function sourceFile(
3043                 $filename,
3044                 callable $lineCallback = null,
3045                 callable $resultCallback = null,
3046                 $fname = false,
3047                 callable $inputCallback = null
3048         ) {
3049                 MediaWiki\suppressWarnings();
3050                 $fp = fopen( $filename, 'r' );
3051                 MediaWiki\restoreWarnings();
3052
3053                 if ( false === $fp ) {
3054                         throw new RuntimeException( "Could not open \"{$filename}\".\n" );
3055                 }
3056
3057                 if ( !$fname ) {
3058                         $fname = __METHOD__ . "( $filename )";
3059                 }
3060
3061                 try {
3062                         $error = $this->sourceStream(
3063                                 $fp, $lineCallback, $resultCallback, $fname, $inputCallback );
3064                 } catch ( Exception $e ) {
3065                         fclose( $fp );
3066                         throw $e;
3067                 }
3068
3069                 fclose( $fp );
3070
3071                 return $error;
3072         }
3073
3074         public function setSchemaVars( $vars ) {
3075                 $this->mSchemaVars = $vars;
3076         }
3077
3078         public function sourceStream(
3079                 $fp,
3080                 callable $lineCallback = null,
3081                 callable $resultCallback = null,
3082                 $fname = __METHOD__,
3083                 callable $inputCallback = null
3084         ) {
3085                 $cmd = '';
3086
3087                 while ( !feof( $fp ) ) {
3088                         if ( $lineCallback ) {
3089                                 call_user_func( $lineCallback );
3090                         }
3091
3092                         $line = trim( fgets( $fp ) );
3093
3094                         if ( $line == '' ) {
3095                                 continue;
3096                         }
3097
3098                         if ( '-' == $line[0] && '-' == $line[1] ) {
3099                                 continue;
3100                         }
3101
3102                         if ( $cmd != '' ) {
3103                                 $cmd .= ' ';
3104                         }
3105
3106                         $done = $this->streamStatementEnd( $cmd, $line );
3107
3108                         $cmd .= "$line\n";
3109
3110                         if ( $done || feof( $fp ) ) {
3111                                 $cmd = $this->replaceVars( $cmd );
3112
3113                                 if ( !$inputCallback || call_user_func( $inputCallback, $cmd ) ) {
3114                                         $res = $this->query( $cmd, $fname );
3115
3116                                         if ( $resultCallback ) {
3117                                                 call_user_func( $resultCallback, $res, $this );
3118                                         }
3119
3120                                         if ( false === $res ) {
3121                                                 $err = $this->lastError();
3122
3123                                                 return "Query \"{$cmd}\" failed with error code \"$err\".\n";
3124                                         }
3125                                 }
3126                                 $cmd = '';
3127                         }
3128                 }
3129
3130                 return true;
3131         }
3132
3133         /**
3134          * Called by sourceStream() to check if we've reached a statement end
3135          *
3136          * @param string &$sql SQL assembled so far
3137          * @param string &$newLine New line about to be added to $sql
3138          * @return bool Whether $newLine contains end of the statement
3139          */
3140         public function streamStatementEnd( &$sql, &$newLine ) {
3141                 if ( $this->delimiter ) {
3142                         $prev = $newLine;
3143                         $newLine = preg_replace(
3144                                 '/' . preg_quote( $this->delimiter, '/' ) . '$/', '', $newLine );
3145                         if ( $newLine != $prev ) {
3146                                 return true;
3147                         }
3148                 }
3149
3150                 return false;
3151         }
3152
3153         /**
3154          * Database independent variable replacement. Replaces a set of variables
3155          * in an SQL statement with their contents as given by $this->getSchemaVars().
3156          *
3157          * Supports '{$var}' `{$var}` and / *$var* / (without the spaces) style variables.
3158          *
3159          * - '{$var}' should be used for text and is passed through the database's
3160          *   addQuotes method.
3161          * - `{$var}` should be used for identifiers (e.g. table and database names).
3162          *   It is passed through the database's addIdentifierQuotes method which
3163          *   can be overridden if the database uses something other than backticks.
3164          * - / *_* / or / *$wgDBprefix* / passes the name that follows through the
3165          *   database's tableName method.
3166          * - / *i* / passes the name that follows through the database's indexName method.
3167          * - In all other cases, / *$var* / is left unencoded. Except for table options,
3168          *   its use should be avoided. In 1.24 and older, string encoding was applied.
3169          *
3170          * @param string $ins SQL statement to replace variables in
3171          * @return string The new SQL statement with variables replaced
3172          */
3173         protected function replaceVars( $ins ) {
3174                 $vars = $this->getSchemaVars();
3175                 return preg_replace_callback(
3176                         '!
3177                                 /\* (\$wgDBprefix|[_i]) \*/ (\w*) | # 1-2. tableName, indexName
3178                                 \'\{\$ (\w+) }\'                  | # 3. addQuotes
3179                                 `\{\$ (\w+) }`                    | # 4. addIdentifierQuotes
3180                                 /\*\$ (\w+) \*/                     # 5. leave unencoded
3181                         !x',
3182                         function ( $m ) use ( $vars ) {
3183                                 // Note: Because of <https://bugs.php.net/bug.php?id=51881>,
3184                                 // check for both nonexistent keys *and* the empty string.
3185                                 if ( isset( $m[1] ) && $m[1] !== '' ) {
3186                                         if ( $m[1] === 'i' ) {
3187                                                 return $this->indexName( $m[2] );
3188                                         } else {
3189                                                 return $this->tableName( $m[2] );
3190                                         }
3191                                 } elseif ( isset( $m[3] ) && $m[3] !== '' && array_key_exists( $m[3], $vars ) ) {
3192                                         return $this->addQuotes( $vars[$m[3]] );
3193                                 } elseif ( isset( $m[4] ) && $m[4] !== '' && array_key_exists( $m[4], $vars ) ) {
3194                                         return $this->addIdentifierQuotes( $vars[$m[4]] );
3195                                 } elseif ( isset( $m[5] ) && $m[5] !== '' && array_key_exists( $m[5], $vars ) ) {
3196                                         return $vars[$m[5]];
3197                                 } else {
3198                                         return $m[0];
3199                                 }
3200                         },
3201                         $ins
3202                 );
3203         }
3204
3205         /**
3206          * Get schema variables. If none have been set via setSchemaVars(), then
3207          * use some defaults from the current object.
3208          *
3209          * @return array
3210          */
3211         protected function getSchemaVars() {
3212                 if ( $this->mSchemaVars ) {
3213                         return $this->mSchemaVars;
3214                 } else {
3215                         return $this->getDefaultSchemaVars();
3216                 }
3217         }
3218
3219         /**
3220          * Get schema variables to use if none have been set via setSchemaVars().
3221          *
3222          * Override this in derived classes to provide variables for tables.sql
3223          * and SQL patch files.
3224          *
3225          * @return array
3226          */
3227         protected function getDefaultSchemaVars() {
3228                 return [];
3229         }
3230
3231         public function lockIsFree( $lockName, $method ) {
3232                 return true;
3233         }
3234
3235         public function lock( $lockName, $method, $timeout = 5 ) {
3236                 $this->mNamedLocksHeld[$lockName] = 1;
3237
3238                 return true;
3239         }
3240
3241         public function unlock( $lockName, $method ) {
3242                 unset( $this->mNamedLocksHeld[$lockName] );
3243
3244                 return true;
3245         }
3246
3247         public function getScopedLockAndFlush( $lockKey, $fname, $timeout ) {
3248                 if ( $this->writesOrCallbacksPending() ) {
3249                         // This only flushes transactions to clear snapshots, not to write data
3250                         $fnames = implode( ', ', $this->pendingWriteAndCallbackCallers() );
3251                         throw new DBUnexpectedError(
3252                                 $this,
3253                                 "$fname: Cannot COMMIT to clear snapshot because writes are pending ($fnames)."
3254                         );
3255                 }
3256
3257                 if ( !$this->lock( $lockKey, $fname, $timeout ) ) {
3258                         return null;
3259                 }
3260
3261                 $unlocker = new ScopedCallback( function () use ( $lockKey, $fname ) {
3262                         if ( $this->trxLevel() ) {
3263                                 // There is a good chance an exception was thrown, causing any early return
3264                                 // from the caller. Let any error handler get a chance to issue rollback().
3265                                 // If there isn't one, let the error bubble up and trigger server-side rollback.
3266                                 $this->onTransactionResolution(
3267                                         function () use ( $lockKey, $fname ) {
3268                                                 $this->unlock( $lockKey, $fname );
3269                                         },
3270                                         $fname
3271                                 );
3272                         } else {
3273                                 $this->unlock( $lockKey, $fname );
3274                         }
3275                 } );
3276
3277                 $this->commit( $fname, self::FLUSHING_INTERNAL );
3278
3279                 return $unlocker;
3280         }
3281
3282         public function namedLocksEnqueue() {
3283                 return false;
3284         }
3285
3286         /**
3287          * Lock specific tables
3288          *
3289          * @param array $read Array of tables to lock for read access
3290          * @param array $write Array of tables to lock for write access
3291          * @param string $method Name of caller
3292          * @param bool $lowPriority Whether to indicate writes to be LOW PRIORITY
3293          * @return bool
3294          */
3295         public function lockTables( $read, $write, $method, $lowPriority = true ) {
3296                 return true;
3297         }
3298
3299         /**
3300          * Unlock specific tables
3301          *
3302          * @param string $method The caller
3303          * @return bool
3304          */
3305         public function unlockTables( $method ) {
3306                 return true;
3307         }
3308
3309         /**
3310          * Delete a table
3311          * @param string $tableName
3312          * @param string $fName
3313          * @return bool|ResultWrapper
3314          * @since 1.18
3315          */
3316         public function dropTable( $tableName, $fName = __METHOD__ ) {
3317                 if ( !$this->tableExists( $tableName, $fName ) ) {
3318                         return false;
3319                 }
3320                 $sql = "DROP TABLE " . $this->tableName( $tableName ) . " CASCADE";
3321
3322                 return $this->query( $sql, $fName );
3323         }
3324
3325         public function getInfinity() {
3326                 return 'infinity';
3327         }
3328
3329         public function encodeExpiry( $expiry ) {
3330                 return ( $expiry == '' || $expiry == 'infinity' || $expiry == $this->getInfinity() )
3331                         ? $this->getInfinity()
3332                         : $this->timestamp( $expiry );
3333         }
3334
3335         public function decodeExpiry( $expiry, $format = TS_MW ) {
3336                 if ( $expiry == '' || $expiry == 'infinity' || $expiry == $this->getInfinity() ) {
3337                         return 'infinity';
3338                 }
3339
3340                 return ConvertibleTimestamp::convert( $format, $expiry );
3341         }
3342
3343         public function setBigSelects( $value = true ) {
3344                 // no-op
3345         }
3346
3347         public function isReadOnly() {
3348                 return ( $this->getReadOnlyReason() !== false );
3349         }
3350
3351         /**
3352          * @return string|bool Reason this DB is read-only or false if it is not
3353          */
3354         protected function getReadOnlyReason() {
3355                 $reason = $this->getLBInfo( 'readOnlyReason' );
3356
3357                 return is_string( $reason ) ? $reason : false;
3358         }
3359
3360         public function setTableAliases( array $aliases ) {
3361                 $this->tableAliases = $aliases;
3362         }
3363
3364         /**
3365          * @return bool Whether a DB user is required to access the DB
3366          * @since 1.28
3367          */
3368         protected function requiresDatabaseUser() {
3369                 return true;
3370         }
3371
3372         /**
3373          * @since 1.19
3374          * @return string
3375          */
3376         public function __toString() {
3377                 return (string)$this->mConn;
3378         }
3379
3380         /**
3381          * Make sure that copies do not share the same client binding handle
3382          * @throws DBConnectionError
3383          */
3384         public function __clone() {
3385                 $this->connLogger->warning(
3386                         "Cloning " . get_class( $this ) . " is not recomended; forking connection:\n" .
3387                         ( new RuntimeException() )->getTraceAsString()
3388                 );
3389
3390                 if ( $this->isOpen() ) {
3391                         // Open a new connection resource without messing with the old one
3392                         $this->mOpened = false;
3393                         $this->mConn = false;
3394                         $this->mTrxEndCallbacks = []; // don't copy
3395                         $this->handleSessionLoss(); // no trx or locks anymore
3396                         $this->open( $this->mServer, $this->mUser, $this->mPassword, $this->mDBname );
3397                         $this->lastPing = microtime( true );
3398                 }
3399         }
3400
3401         /**
3402          * Called by serialize. Throw an exception when DB connection is serialized.
3403          * This causes problems on some database engines because the connection is
3404          * not restored on unserialize.
3405          */
3406         public function __sleep() {
3407                 throw new RuntimeException( 'Database serialization may cause problems, since ' .
3408                         'the connection is not restored on wakeup.' );
3409         }
3410
3411         /**
3412          * Run a few simple sanity checks and close dangling connections
3413          */
3414         public function __destruct() {
3415                 if ( $this->mTrxLevel && $this->mTrxDoneWrites ) {
3416                         trigger_error( "Uncommitted DB writes (transaction from {$this->mTrxFname})." );
3417                 }
3418
3419                 $danglingWriters = $this->pendingWriteAndCallbackCallers();
3420                 if ( $danglingWriters ) {
3421                         $fnames = implode( ', ', $danglingWriters );
3422                         trigger_error( "DB transaction writes or callbacks still pending ($fnames)." );
3423                 }
3424
3425                 if ( $this->mConn ) {
3426                         // Avoid connection leaks for sanity
3427                         $this->closeConnection();
3428                         $this->mConn = false;
3429                         $this->mOpened = false;
3430                 }
3431         }
3432 }
3433
3434 class_alias( 'Database', 'DatabaseBase' );