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
  29 /**
  30  * Database abstraction object
  31  * @ingroup Database
  32  */
  33 abstract class Database implements IDatabase, LoggerAwareInterface {
  34         /** Number of times to re-try an operation in case of deadlock */
  35         const DEADLOCK_TRIES = 4;
  36         /** Minimum time to wait before retry, in microseconds */
  37         const DEADLOCK_DELAY_MIN = 500000;
  38         /** Maximum time to wait before retry */
  39         const DEADLOCK_DELAY_MAX = 1500000;
  40
  41         /** How long before it is worth doing a dummy query to test the connection */
  42         const PING_TTL = 1.0;
  43         const PING_QUERY = 'SELECT 1 AS ping';
  44
  45         const TINY_WRITE_SEC = .010;
  46         const SLOW_WRITE_SEC = .500;
  47         const SMALL_WRITE_ROWS = 100;
  48
  49         /** @var string SQL query */
  50         protected $mLastQuery = '';
  51         /** @var bool */
  52         protected $mDoneWrites = false;
  53         /** @var string|bool */
  54         protected $mPHPError = false;
  55         /** @var string */
  56         protected $mServer;
  57         /** @var string */
  58         protected $mUser;
  59         /** @var string */
  60         protected $mPassword;
  61         /** @var string */
  62         protected $mDBname;
  63         /** @var array[] $aliases Map of (table => (dbname, schema, prefix) map) */
  64         protected $tableAliases = [];
  65         /** @var bool Whether this PHP instance is for a CLI script */
  66         protected $cliMode;
  67         /** @var string Agent name for query profiling */
  68         protected $agent;
  69
  70         /** @var BagOStuff APC cache */
  71         protected $srvCache;
  72         /** @var LoggerInterface */
  73         protected $connLogger;
  74         /** @var LoggerInterface */
  75         protected $queryLogger;
  76         /** @var callback Error logging callback */
  77         protected $errorLogger;
  78
  79         /** @var resource Database connection */
  80         protected $mConn = null;
  81         /** @var bool */
  82         protected $mOpened = false;
  83
  84         /** @var array[] List of (callable, method name) */
  85         protected $mTrxIdleCallbacks = [];
  86         /** @var array[] List of (callable, method name) */
  87         protected $mTrxPreCommitCallbacks = [];
  88         /** @var array[] List of (callable, method name) */
  89         protected $mTrxEndCallbacks = [];
  90         /** @var callable[] Map of (name => callable) */
  91         protected $mTrxRecurringCallbacks = [];
  92         /** @var bool Whether to suppress triggering of transaction end callbacks */
  93         protected $mTrxEndCallbacksSuppressed = false;
  94
  95         /** @var string */
  96         protected $mTablePrefix = '';
  97         /** @var string */
  98         protected $mSchema = '';
  99         /** @var integer */
 100         protected $mFlags;
 101         /** @var array */
 102         protected $mLBInfo = [];
 103         /** @var bool|null */
 104         protected $mDefaultBigSelects = null;
 105         /** @var array|bool */
 106         protected $mSchemaVars = false;
 107         /** @var array */
 108         protected $mSessionVars = [];
 109         /** @var array|null */
 110         protected $preparedArgs;
 111         /** @var string|bool|null Stashed value of html_errors INI setting */
 112         protected $htmlErrors;
 113         /** @var string */
 114         protected $delimiter = ';';
 115         /** @var DatabaseDomain */
 116         protected $currentDomain;
 117
 118         /**
 119          * Either 1 if a transaction is active or 0 otherwise.
 120          * The other Trx fields may not be meaningfull if this is 0.
 121          *
 122          * @var int
 123          */
 124         protected $mTrxLevel = 0;
 125         /**
 126          * Either a short hexidecimal string if a transaction is active or ""
 127          *
 128          * @var string
 129          * @see DatabaseBase::mTrxLevel
 130          */
 131         protected $mTrxShortId = '';
 132         /**
 133          * The UNIX time that the transaction started. Callers can assume that if
 134          * snapshot isolation is used, then the data is *at least* up to date to that
 135          * point (possibly more up-to-date since the first SELECT defines the snapshot).
 136          *
 137          * @var float|null
 138          * @see DatabaseBase::mTrxLevel
 139          */
 140         private $mTrxTimestamp = null;
 141         /** @var float Lag estimate at the time of BEGIN */
 142         private $mTrxReplicaLag = null;
 143         /**
 144          * Remembers the function name given for starting the most recent transaction via begin().
 145          * Used to provide additional context for error reporting.
 146          *
 147          * @var string
 148          * @see DatabaseBase::mTrxLevel
 149          */
 150         private $mTrxFname = null;
 151         /**
 152          * Record if possible write queries were done in the last transaction started
 153          *
 154          * @var bool
 155          * @see DatabaseBase::mTrxLevel
 156          */
 157         private $mTrxDoneWrites = false;
 158         /**
 159          * Record if the current transaction was started implicitly due to DBO_TRX being set.
 160          *
 161          * @var bool
 162          * @see DatabaseBase::mTrxLevel
 163          */
 164         private $mTrxAutomatic = false;
 165         /**
 166          * Array of levels of atomicity within transactions
 167          *
 168          * @var array
 169          */
 170         private $mTrxAtomicLevels = [];
 171         /**
 172          * Record if the current transaction was started implicitly by DatabaseBase::startAtomic
 173          *
 174          * @var bool
 175          */
 176         private $mTrxAutomaticAtomic = false;
 177         /**
 178          * Track the write query callers of the current transaction
 179          *
 180          * @var string[]
 181          */
 182         private $mTrxWriteCallers = [];
 183         /**
 184          * @var float Seconds spent in write queries for the current transaction
 185          */
 186         private $mTrxWriteDuration = 0.0;
 187         /**
 188          * @var integer Number of write queries for the current transaction
 189          */
 190         private $mTrxWriteQueryCount = 0;
 191         /**
 192          * @var float Like mTrxWriteQueryCount but excludes lock-bound, easy to replicate, queries
 193          */
 194         private $mTrxWriteAdjDuration = 0.0;
 195         /**
 196          * @var integer Number of write queries counted in mTrxWriteAdjDuration
 197          */
 198         private $mTrxWriteAdjQueryCount = 0;
 199         /**
 200          * @var float RTT time estimate
 201          */
 202         private $mRTTEstimate = 0.0;
 203
 204         /** @var array Map of (name => 1) for locks obtained via lock() */
 205         private $mNamedLocksHeld = [];
 206         /** @var array Map of (table name => 1) for TEMPORARY tables */
 207         protected $mSessionTempTables = [];
 208
 209         /** @var IDatabase|null Lazy handle to the master DB this server replicates from */
 210         private $lazyMasterHandle;
 211
 212         /**
 213          * @since 1.22
 214          * @var string[] Process cache of VIEWs names in the database
 215          */
 216         protected $allViews = null;
 217
 218         /** @var float UNIX timestamp */
 219         protected $lastPing = 0.0;
 220
 221         /** @var int[] Prior mFlags values */
 222         private $priorFlags = [];
 223
 224         /** @var object|string Class name or object With profileIn/profileOut methods */
 225         protected $profiler;
 226         /** @var TransactionProfiler */
 227         protected $trxProfiler;
 228
 229         /**
 230          * Constructor and database handle and attempt to connect to the DB server
 231          *
 232          * IDatabase classes should not be constructed directly in external
 233          * code. Database::factory() should be used instead.
 234          *
 235          * @param array $params Parameters passed from Database::factory()
 236          */
 237         function __construct( array $params ) {
 238                 $server = $params['host'];
 239                 $user = $params['user'];
 240                 $password = $params['password'];
 241                 $dbName = $params['dbname'];
 242
 243                 $this->mSchema = $params['schema'];
 244                 $this->mTablePrefix = $params['tablePrefix'];
 245
 246                 $this->cliMode = $params['cliMode'];
 247                 // Agent name is added to SQL queries in a comment, so make sure it can't break out
 248                 $this->agent = str_replace( '/', '-', $params['agent'] );
 249
 250                 $this->mFlags = $params['flags'];
 251                 if ( $this->mFlags & DBO_DEFAULT ) {
 252                         if ( $this->cliMode ) {
 253                                 $this->mFlags &= ~DBO_TRX;
 254                         } else {
 255                                 $this->mFlags |= DBO_TRX;
 256                         }
 257                 }
 258
 259                 $this->mSessionVars = $params['variables'];
 260
 261                 $this->srvCache = isset( $params['srvCache'] )
 262                         ? $params['srvCache']
 263                         : new HashBagOStuff();
 264
 265                 $this->profiler = $params['profiler'];
 266                 $this->trxProfiler = $params['trxProfiler'];
 267                 $this->connLogger = $params['connLogger'];
 268                 $this->queryLogger = $params['queryLogger'];
 269
 270                 // Set initial dummy domain until open() sets the final DB/prefix
 271                 $this->currentDomain = DatabaseDomain::newUnspecified();
 272
 273                 if ( $user ) {
 274                         $this->open( $server, $user, $password, $dbName );
 275                 } elseif ( $this->requiresDatabaseUser() ) {
 276                         throw new InvalidArgumentException( "No database user provided." );
 277                 }
 278
 279                 // Set the domain object after open() sets the relevant fields
 280                 if ( $this->mDBname != '' ) {
 281                         // Domains with server scope but a table prefix are not used by IDatabase classes
 282                         $this->currentDomain = new DatabaseDomain( $this->mDBname, null, $this->mTablePrefix );
 283                 }
 284         }
 285
 286         /**
 287          * Construct a Database subclass instance given a database type and parameters
 288          *
 289          * This also connects to the database immediately upon object construction
 290          *
 291          * @param string $dbType A possible DB type (sqlite, mysql, postgres)
 292          * @param array $p Parameter map with keys:
 293          *   - host : The hostname of the DB server
 294          *   - user : The name of the database user the client operates under
 295          *   - password : The password for the database user
 296          *   - dbname : The name of the database to use where queries do not specify one.
 297          *      The database must exist or an error might be thrown. Setting this to the empty string
 298          *      will avoid any such errors and make the handle have no implicit database scope. This is
 299          *      useful for queries like SHOW STATUS, CREATE DATABASE, or DROP DATABASE. Note that a
 300          *      "database" in Postgres is rougly equivalent to an entire MySQL server. This the domain
 301          *      in which user names and such are defined, e.g. users are database-specific in Postgres.
 302          *   - schema : The database schema to use (if supported). A "schema" in Postgres is roughly
 303          *      equivalent to a "database" in MySQL. Note that MySQL and SQLite do not use schemas.
 304          *   - tablePrefix : Optional table prefix that is implicitly added on to all table names
 305          *      recognized in queries. This can be used in place of schemas for handle site farms.
 306          *   - flags : Optional bitfield of DBO_* constants that define connection, protocol,
 307          *      buffering, and transaction behavior. It is STRONGLY adviced to leave the DBO_DEFAULT
 308          *      flag in place UNLESS this this database simply acts as a key/value store.
 309          *   - driver: Optional name of a specific DB client driver. For MySQL, there is the old
 310          *      'mysql' driver and the newer 'mysqli' driver.
 311          *   - variables: Optional map of session variables to set after connecting. This can be
 312          *      used to adjust lock timeouts or encoding modes and the like.
 313          *   - connLogger: Optional PSR-3 logger interface instance.
 314          *   - queryLogger: Optional PSR-3 logger interface instance.
 315          *   - profiler: Optional class name or object with profileIn()/profileOut() methods.
 316          *      These will be called in query(), using a simplified version of the SQL that also
 317          *      includes the agent as a SQL comment.
 318          *   - trxProfiler: Optional TransactionProfiler instance.
 319          *   - errorLogger: Optional callback that takes an Exception and logs it.
 320          *   - cliMode: Whether to consider the execution context that of a CLI script.
 321          *   - agent: Optional name used to identify the end-user in query profiling/logging.
 322          *   - srvCache: Optional BagOStuff instance to an APC-style cache.
 323          * @return Database|null If the database driver or extension cannot be found
 324          * @throws InvalidArgumentException If the database driver or extension cannot be found
 325          * @since 1.18
 326          */
 327         final public static function factory( $dbType, $p = [] ) {
 328                 static $canonicalDBTypes = [
 329                         'mysql' => [ 'mysqli', 'mysql' ],
 330                         'postgres' => [],
 331                         'sqlite' => [],
 332                         'oracle' => [],
 333                         'mssql' => [],
 334                 ];
 335
 336                 $driver = false;
 337                 $dbType = strtolower( $dbType );
 338                 if ( isset( $canonicalDBTypes[$dbType] ) && $canonicalDBTypes[$dbType] ) {
 339                         $possibleDrivers = $canonicalDBTypes[$dbType];
 340                         if ( !empty( $p['driver'] ) ) {
 341                                 if ( in_array( $p['driver'], $possibleDrivers ) ) {
 342                                         $driver = $p['driver'];
 343                                 } else {
 344                                         throw new InvalidArgumentException( __METHOD__ .
 345                                                 " type '$dbType' does not support driver '{$p['driver']}'" );
 346                                 }
 347                         } else {
 348                                 foreach ( $possibleDrivers as $posDriver ) {
 349                                         if ( extension_loaded( $posDriver ) ) {
 350                                                 $driver = $posDriver;
 351                                                 break;
 352                                         }
 353                                 }
 354                         }
 355                 } else {
 356                         $driver = $dbType;
 357                 }
 358                 if ( $driver === false ) {
 359                         throw new InvalidArgumentException( __METHOD__ .
 360                                 " no viable database extension found for type '$dbType'" );
 361                 }
 362
 363                 $class = 'Database' . ucfirst( $driver );
 364                 if ( class_exists( $class ) && is_subclass_of( $class, 'IDatabase' ) ) {
 365                         // Resolve some defaults for b/c
 366                         $p['host'] = isset( $p['host'] ) ? $p['host'] : false;
 367                         $p['user'] = isset( $p['user'] ) ? $p['user'] : false;
 368                         $p['password'] = isset( $p['password'] ) ? $p['password'] : false;
 369                         $p['dbname'] = isset( $p['dbname'] ) ? $p['dbname'] : false;
 370                         $p['flags'] = isset( $p['flags'] ) ? $p['flags'] : 0;
 371                         $p['variables'] = isset( $p['variables'] ) ? $p['variables'] : [];
 372                         $p['tablePrefix'] = isset( $p['tablePrefix'] ) ? $p['tablePrefix'] : '';
 373                         $p['schema'] = isset( $p['schema'] ) ? $p['schema'] : '';
 374                         $p['cliMode'] = isset( $p['cliMode'] ) ? $p['cliMode'] : ( PHP_SAPI === 'cli' );
 375                         $p['agent'] = isset( $p['agent'] ) ? $p['agent'] : '';
 376                         if ( !isset( $p['connLogger'] ) ) {
 377                                 $p['connLogger'] = new \Psr\Log\NullLogger();
 378                         }
 379                         if ( !isset( $p['queryLogger'] ) ) {
 380                                 $p['queryLogger'] = new \Psr\Log\NullLogger();
 381                         }
 382                         $p['profiler'] = isset( $p['profiler'] ) ? $p['profiler'] : null;
 383                         if ( !isset( $p['trxProfiler'] ) ) {
 384                                 $p['trxProfiler'] = new TransactionProfiler();
 385                         }
 386                         if ( !isset( $p['errorLogger'] ) ) {
 387                                 $p['errorLogger'] = function ( Exception $e ) {
 388                                         trigger_error( get_class( $e ) . ': ' . $e->getMessage(), E_WARNING );
 389                                 };
 390                         }
 391
 392                         $conn = new $class( $p );
 393                 } else {
 394                         $conn = null;
 395                 }
 396
 397                 return $conn;
 398         }
 399
 400         public function setLogger( LoggerInterface $logger ) {
 401                 $this->queryLogger = $logger;
 402         }
 403
 404         public function getServerInfo() {
 405                 return $this->getServerVersion();
 406         }
 407
 408         public function bufferResults( $buffer = null ) {
 409                 $res = !$this->getFlag( DBO_NOBUFFER );
 410                 if ( $buffer !== null ) {
 411                         $buffer ? $this->clearFlag( DBO_NOBUFFER ) : $this->setFlag( 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( DBO_IGNORE );
 431                 if ( $ignoreErrors !== null ) {
 432                         $ignoreErrors ? $this->setFlag( DBO_IGNORE ) : $this->clearFlag( DBO_IGNORE );
 433                 }
 434
 435                 return $res;
 436         }
 437
 438         public function trxLevel() {
 439                 return $this->mTrxLevel;
 440         }
 441
 442         public function trxTimestamp() {
 443                 return $this->mTrxLevel ? $this->mTrxTimestamp : null;
 444         }
 445
 446         public function tablePrefix( $prefix = null ) {
 447                 $old = $this->mTablePrefix;
 448                 if ( $prefix !== null ) {
 449                         $this->mTablePrefix = $prefix;
 450                         $this->currentDomain = ( $this->mDBname != '' )
 451                                 ? new DatabaseDomain( $this->mDBname, null, $this->mTablePrefix )
 452                                 : DatabaseDomain::newUnspecified();
 453                 }
 454
 455                 return $old;
 456         }
 457
 458         public function dbSchema( $schema = null ) {
 459                 $old = $this->mSchema;
 460                 if ( $schema !== null ) {
 461                         $this->mSchema = $schema;
 462                 }
 463
 464                 return $old;
 465         }
 466
 467         public function getLBInfo( $name = null ) {
 468                 if ( is_null( $name ) ) {
 469                         return $this->mLBInfo;
 470                 } else {
 471                         if ( array_key_exists( $name, $this->mLBInfo ) ) {
 472                                 return $this->mLBInfo[$name];
 473                         } else {
 474                                 return null;
 475                         }
 476                 }
 477         }
 478
 479         public function setLBInfo( $name, $value = null ) {
 480                 if ( is_null( $value ) ) {
 481                         $this->mLBInfo = $name;
 482                 } else {
 483                         $this->mLBInfo[$name] = $value;
 484                 }
 485         }
 486
 487         public function setLazyMasterHandle( IDatabase $conn ) {
 488                 $this->lazyMasterHandle = $conn;
 489         }
 490
 491         /**
 492          * @return IDatabase|null
 493          * @see setLazyMasterHandle()
 494          * @since 1.27
 495          */
 496         public function getLazyMasterHandle() {
 497                 return $this->lazyMasterHandle;
 498         }
 499
 500         public function implicitGroupby() {
 501                 return true;
 502         }
 503
 504         public function implicitOrderby() {
 505                 return true;
 506         }
 507
 508         public function lastQuery() {
 509                 return $this->mLastQuery;
 510         }
 511
 512         public function doneWrites() {
 513                 return (bool)$this->mDoneWrites;
 514         }
 515
 516         public function lastDoneWrites() {
 517                 return $this->mDoneWrites ?: false;
 518         }
 519
 520         public function writesPending() {
 521                 return $this->mTrxLevel && $this->mTrxDoneWrites;
 522         }
 523
 524         public function writesOrCallbacksPending() {
 525                 return $this->mTrxLevel && (
 526                         $this->mTrxDoneWrites || $this->mTrxIdleCallbacks || $this->mTrxPreCommitCallbacks
 527                 );
 528         }
 529
 530         public function pendingWriteQueryDuration( $type = self::ESTIMATE_TOTAL ) {
 531                 if ( !$this->mTrxLevel ) {
 532                         return false;
 533                 } elseif ( !$this->mTrxDoneWrites ) {
 534                         return 0.0;
 535                 }
 536
 537                 switch ( $type ) {
 538                         case self::ESTIMATE_DB_APPLY:
 539                                 $this->ping( $rtt );
 540                                 $rttAdjTotal = $this->mTrxWriteAdjQueryCount * $rtt;
 541                                 $applyTime = max( $this->mTrxWriteAdjDuration - $rttAdjTotal, 0 );
 542                                 // For omitted queries, make them count as something at least
 543                                 $omitted = $this->mTrxWriteQueryCount - $this->mTrxWriteAdjQueryCount;
 544                                 $applyTime += self::TINY_WRITE_SEC * $omitted;
 545
 546                                 return $applyTime;
 547                         default: // everything
 548                                 return $this->mTrxWriteDuration;
 549                 }
 550         }
 551
 552         public function pendingWriteCallers() {
 553                 return $this->mTrxLevel ? $this->mTrxWriteCallers : [];
 554         }
 555
 556         protected function pendingWriteAndCallbackCallers() {
 557                 if ( !$this->mTrxLevel ) {
 558                         return [];
 559                 }
 560
 561                 $fnames = $this->mTrxWriteCallers;
 562                 foreach ( [
 563                         $this->mTrxIdleCallbacks,
 564                         $this->mTrxPreCommitCallbacks,
 565                         $this->mTrxEndCallbacks
 566                 ] as $callbacks ) {
 567                         foreach ( $callbacks as $callback ) {
 568                                 $fnames[] = $callback[1];
 569                         }
 570                 }
 571
 572                 return $fnames;
 573         }
 574
 575         public function isOpen() {
 576                 return $this->mOpened;
 577         }
 578
 579         public function setFlag( $flag, $remember = self::REMEMBER_NOTHING ) {
 580                 if ( $remember === self::REMEMBER_PRIOR ) {
 581                         array_push( $this->priorFlags, $this->mFlags );
 582                 }
 583                 $this->mFlags |= $flag;
 584         }
 585
 586         public function clearFlag( $flag, $remember = self::REMEMBER_NOTHING ) {
 587                 if ( $remember === self::REMEMBER_PRIOR ) {
 588                         array_push( $this->priorFlags, $this->mFlags );
 589                 }
 590                 $this->mFlags &= ~$flag;
 591         }
 592
 593         public function restoreFlags( $state = self::RESTORE_PRIOR ) {
 594                 if ( !$this->priorFlags ) {
 595                         return;
 596                 }
 597
 598                 if ( $state === self::RESTORE_INITIAL ) {
 599                         $this->mFlags = reset( $this->priorFlags );
 600                         $this->priorFlags = [];
 601                 } else {
 602                         $this->mFlags = array_pop( $this->priorFlags );
 603                 }
 604         }
 605
 606         public function getFlag( $flag ) {
 607                 return !!( $this->mFlags & $flag );
 608         }
 609
 610         public function getProperty( $name ) {
 611                 return $this->$name;
 612         }
 613
 614         public function getDomainID() {
 615                 return $this->currentDomain->getId();
 616         }
 617
 618         final public function getWikiID() {
 619                 return $this->getDomainID();
 620         }
 621
 622         /**
 623          * Get information about an index into an object
 624          * @param string $table Table name
 625          * @param string $index Index name
 626          * @param string $fname Calling function name
 627          * @return mixed Database-specific index description class or false if the index does not exist
 628          */
 629         abstract function indexInfo( $table, $index, $fname = __METHOD__ );
 630
 631         /**
 632          * Wrapper for addslashes()
 633          *
 634          * @param string $s String to be slashed.
 635          * @return string Slashed string.
 636          */
 637         abstract function strencode( $s );
 638
 639         protected function installErrorHandler() {
 640                 $this->mPHPError = false;
 641                 $this->htmlErrors = ini_set( 'html_errors', '0' );
 642                 set_error_handler( [ $this, 'connectionErrorLogger' ] );
 643         }
 644
 645         /**
 646          * @return bool|string
 647          */
 648         protected function restoreErrorHandler() {
 649                 restore_error_handler();
 650                 if ( $this->htmlErrors !== false ) {
 651                         ini_set( 'html_errors', $this->htmlErrors );
 652                 }
 653                 if ( $this->mPHPError ) {
 654                         $error = preg_replace( '!\[<a.*</a>\]!', '', $this->mPHPError );
 655                         $error = preg_replace( '!^.*?:\s?(.*)$!', '$1', $error );
 656
 657                         return $error;
 658                 } else {
 659                         return false;
 660                 }
 661         }
 662
 663         /**
 664          * This method should not be used outside of Database classes
 665          *
 666          * @param int $errno
 667          * @param string $errstr
 668          */
 669         public function connectionErrorLogger( $errno, $errstr ) {
 670                 $this->mPHPError = $errstr;
 671         }
 672
 673         /**
 674          * Create a log context to pass to PSR-3 logger functions.
 675          *
 676          * @param array $extras Additional data to add to context
 677          * @return array
 678          */
 679         protected function getLogContext( array $extras = [] ) {
 680                 return array_merge(
 681                         [
 682                                 'db_server' => $this->mServer,
 683                                 'db_name' => $this->mDBname,
 684                                 'db_user' => $this->mUser,
 685                         ],
 686                         $extras
 687                 );
 688         }
 689
 690         public function close() {
 691                 if ( $this->mConn ) {
 692                         if ( $this->trxLevel() ) {
 693                                 $this->commit( __METHOD__, self::FLUSHING_INTERNAL );
 694                         }
 695
 696                         $closed = $this->closeConnection();
 697                         $this->mConn = false;
 698                 } elseif ( $this->mTrxIdleCallbacks || $this->mTrxEndCallbacks ) { // sanity
 699                         throw new RuntimeException( "Transaction callbacks still pending." );
 700                 } else {
 701                         $closed = true;
 702                 }
 703                 $this->mOpened = false;
 704
 705                 return $closed;
 706         }
 707
 708         /**
 709          * Make sure isOpen() returns true as a sanity check
 710          *
 711          * @throws DBUnexpectedError
 712          */
 713         protected function assertOpen() {
 714                 if ( !$this->isOpen() ) {
 715                         throw new DBUnexpectedError( $this, "DB connection was already closed." );
 716                 }
 717         }
 718
 719         /**
 720          * Closes underlying database connection
 721          * @since 1.20
 722          * @return bool Whether connection was closed successfully
 723          */
 724         abstract protected function closeConnection();
 725
 726         public function reportConnectionError( $error = 'Unknown error' ) {
 727                 $myError = $this->lastError();
 728                 if ( $myError ) {
 729                         $error = $myError;
 730                 }
 731
 732                 # New method
 733                 throw new DBConnectionError( $this, $error );
 734         }
 735
 736         /**
 737          * The DBMS-dependent part of query()
 738          *
 739          * @param string $sql SQL query.
 740          * @return ResultWrapper|bool Result object to feed to fetchObject,
 741          *   fetchRow, ...; or false on failure
 742          */
 743         abstract protected function doQuery( $sql );
 744
 745         /**
 746          * Determine whether a query writes to the DB.
 747          * Should return true if unsure.
 748          *
 749          * @param string $sql
 750          * @return bool
 751          */
 752         protected function isWriteQuery( $sql ) {
 753                 return !preg_match(
 754                         '/^(?:SELECT|BEGIN|ROLLBACK|COMMIT|SET|SHOW|EXPLAIN|\(SELECT)\b/i', $sql );
 755         }
 756
 757         /**
 758          * @param $sql
 759          * @return string|null
 760          */
 761         protected function getQueryVerb( $sql ) {
 762                 return preg_match( '/^\s*([a-z]+)/i', $sql, $m ) ? strtoupper( $m[1] ) : null;
 763         }
 764
 765         /**
 766          * Determine whether a SQL statement is sensitive to isolation level.
 767          * A SQL statement is considered transactable if its result could vary
 768          * depending on the transaction isolation level. Operational commands
 769          * such as 'SET' and 'SHOW' are not considered to be transactable.
 770          *
 771          * @param string $sql
 772          * @return bool
 773          */
 774         protected function isTransactableQuery( $sql ) {
 775                 $verb = $this->getQueryVerb( $sql );
 776                 return !in_array( $verb, [ 'BEGIN', 'COMMIT', 'ROLLBACK', 'SHOW', 'SET' ], true );
 777         }
 778
 779         /**
 780          * @param string $sql A SQL query
 781          * @return bool Whether $sql is SQL for creating/dropping a new TEMPORARY table
 782          */
 783         protected function registerTempTableOperation( $sql ) {
 784                 if ( preg_match(
 785                         '/^CREATE\s+TEMPORARY\s+TABLE\s+(?:IF\s+NOT\s+EXISTS\s+)?[`"\']?(\w+)[`"\']?/i',
 786                         $sql,
 787                         $matches
 788                 ) ) {
 789                         $this->mSessionTempTables[$matches[1]] = 1;
 790
 791                         return true;
 792                 } elseif ( preg_match(
 793                         '/^DROP\s+(?:TEMPORARY\s+)?TABLE\s+(?:IF\s+EXISTS\s+)?[`"\']?(\w+)[`"\']?/i',
 794                         $sql,
 795                         $matches
 796                 ) ) {
 797                         unset( $this->mSessionTempTables[$matches[1]] );
 798
 799                         return true;
 800                 } elseif ( preg_match(
 801                         '/^(?:INSERT\s+(?:\w+\s+)?INTO|UPDATE|DELETE\s+FROM)\s+[`"\']?(\w+)[`"\']?/i',
 802                         $sql,
 803                         $matches
 804                 ) ) {
 805                         return isset( $this->mSessionTempTables[$matches[1]] );
 806                 }
 807
 808                 return false;
 809         }
 810
 811         public function query( $sql, $fname = __METHOD__, $tempIgnore = false ) {
 812                 $priorWritesPending = $this->writesOrCallbacksPending();
 813                 $this->mLastQuery = $sql;
 814
 815                 $isWrite = $this->isWriteQuery( $sql ) && !$this->registerTempTableOperation( $sql );
 816                 if ( $isWrite ) {
 817                         $reason = $this->getReadOnlyReason();
 818                         if ( $reason !== false ) {
 819                                 throw new DBReadOnlyError( $this, "Database is read-only: $reason" );
 820                         }
 821                         # Set a flag indicating that writes have been done
 822                         $this->mDoneWrites = microtime( true );
 823                 }
 824
 825                 // Add trace comment to the begin of the sql string, right after the operator.
 826                 // Or, for one-word queries (like "BEGIN" or COMMIT") add it to the end (bug 42598)
 827                 $commentedSql = preg_replace( '/\s|$/', " /* $fname {$this->agent} */ ", $sql, 1 );
 828
 829                 # Start implicit transactions that wrap the request if DBO_TRX is enabled
 830                 if ( !$this->mTrxLevel && $this->getFlag( DBO_TRX )
 831                         && $this->isTransactableQuery( $sql )
 832                 ) {
 833                         $this->begin( __METHOD__ . " ($fname)", self::TRANSACTION_INTERNAL );
 834                         $this->mTrxAutomatic = true;
 835                 }
 836
 837                 # Keep track of whether the transaction has write queries pending
 838                 if ( $this->mTrxLevel && !$this->mTrxDoneWrites && $isWrite ) {
 839                         $this->mTrxDoneWrites = true;
 840                         $this->trxProfiler->transactionWritingIn(
 841                                 $this->mServer, $this->mDBname, $this->mTrxShortId );
 842                 }
 843
 844                 if ( $this->getFlag( DBO_DEBUG ) ) {
 845                         $this->queryLogger->debug( "{$this->mDBname} {$commentedSql}" );
 846                 }
 847
 848                 # Avoid fatals if close() was called
 849                 $this->assertOpen();
 850
 851                 # Send the query to the server
 852                 $ret = $this->doProfiledQuery( $sql, $commentedSql, $isWrite, $fname );
 853
 854                 # Try reconnecting if the connection was lost
 855                 if ( false === $ret && $this->wasErrorReissuable() ) {
 856                         $recoverable = $this->canRecoverFromDisconnect( $sql, $priorWritesPending );
 857                         # Stash the last error values before anything might clear them
 858                         $lastError = $this->lastError();
 859                         $lastErrno = $this->lastErrno();
 860                         # Update state tracking to reflect transaction loss due to disconnection
 861                         $this->handleSessionLoss();
 862                         if ( $this->reconnect() ) {
 863                                 $msg = __METHOD__ . ": lost connection to {$this->getServer()}; reconnected";
 864                                 $this->connLogger->warning( $msg );
 865                                 $this->queryLogger->warning(
 866                                         "$msg:\n" . ( new RuntimeException() )->getTraceAsString() );
 867
 868                                 if ( !$recoverable ) {
 869                                         # Callers may catch the exception and continue to use the DB
 870                                         $this->reportQueryError( $lastError, $lastErrno, $sql, $fname );
 871                                 } else {
 872                                         # Should be safe to silently retry the query
 873                                         $ret = $this->doProfiledQuery( $sql, $commentedSql, $isWrite, $fname );
 874                                 }
 875                         } else {
 876                                 $msg = __METHOD__ . ": lost connection to {$this->getServer()} permanently";
 877                                 $this->connLogger->error( $msg );
 878                         }
 879                 }
 880
 881                 if ( false === $ret ) {
 882                         # Deadlocks cause the entire transaction to abort, not just the statement.
 883                         # http://dev.mysql.com/doc/refman/5.7/en/innodb-error-handling.html
 884                         # https://www.postgresql.org/docs/9.1/static/explicit-locking.html
 885                         if ( $this->wasDeadlock() ) {
 886                                 if ( $this->explicitTrxActive() || $priorWritesPending ) {
 887                                         $tempIgnore = false; // not recoverable
 888                                 }
 889                                 # Update state tracking to reflect transaction loss
 890                                 $this->handleSessionLoss();
 891                         }
 892
 893                         $this->reportQueryError(
 894                                 $this->lastError(), $this->lastErrno(), $sql, $fname, $tempIgnore );
 895                 }
 896
 897                 $res = $this->resultObject( $ret );
 898
 899                 return $res;
 900         }
 901
 902         private function doProfiledQuery( $sql, $commentedSql, $isWrite, $fname ) {
 903                 $isMaster = !is_null( $this->getLBInfo( 'master' ) );
 904                 # generalizeSQL() will probably cut down the query to reasonable
 905                 # logging size most of the time. The substr is really just a sanity check.
 906                 if ( $isMaster ) {
 907                         $queryProf = 'query-m: ' . substr( self::generalizeSQL( $sql ), 0, 255 );
 908                 } else {
 909                         $queryProf = 'query: ' . substr( self::generalizeSQL( $sql ), 0, 255 );
 910                 }
 911
 912                 # Include query transaction state
 913                 $queryProf .= $this->mTrxShortId ? " [TRX#{$this->mTrxShortId}]" : "";
 914
 915                 $startTime = microtime( true );
 916                 if ( $this->profiler ) {
 917                         call_user_func( [ $this->profiler, 'profileIn' ], $queryProf );
 918                 }
 919                 $ret = $this->doQuery( $commentedSql );
 920                 if ( $this->profiler ) {
 921                         call_user_func( [ $this->profiler, 'profileOut' ], $queryProf );
 922                 }
 923                 $queryRuntime = max( microtime( true ) - $startTime, 0.0 );
 924
 925                 unset( $queryProfSection ); // profile out (if set)
 926
 927                 if ( $ret !== false ) {
 928                         $this->lastPing = $startTime;
 929                         if ( $isWrite && $this->mTrxLevel ) {
 930                                 $this->updateTrxWriteQueryTime( $sql, $queryRuntime );
 931                                 $this->mTrxWriteCallers[] = $fname;
 932                         }
 933                 }
 934
 935                 if ( $sql === self::PING_QUERY ) {
 936                         $this->mRTTEstimate = $queryRuntime;
 937                 }
 938
 939                 $this->trxProfiler->recordQueryCompletion(
 940                         $queryProf, $startTime, $isWrite, $this->affectedRows()
 941                 );
 942                 $this->queryLogger->debug( $sql, [
 943                         'method' => $fname,
 944                         'master' => $isMaster,
 945                         'runtime' => $queryRuntime,
 946                 ] );
 947
 948                 return $ret;
 949         }
 950
 951         /**
 952          * Update the estimated run-time of a query, not counting large row lock times
 953          *
 954          * LoadBalancer can be set to rollback transactions that will create huge replication
 955          * lag. It bases this estimate off of pendingWriteQueryDuration(). Certain simple
 956          * queries, like inserting a row can take a long time due to row locking. This method
 957          * uses some simple heuristics to discount those cases.
 958          *
 959          * @param string $sql A SQL write query
 960          * @param float $runtime Total runtime, including RTT
 961          */
 962         private function updateTrxWriteQueryTime( $sql, $runtime ) {
 963                 // Whether this is indicative of replica DB runtime (except for RBR or ws_repl)
 964                 $indicativeOfReplicaRuntime = true;
 965                 if ( $runtime > self::SLOW_WRITE_SEC ) {
 966                         $verb = $this->getQueryVerb( $sql );
 967                         // insert(), upsert(), replace() are fast unless bulky in size or blocked on locks
 968                         if ( $verb === 'INSERT' ) {
 969                                 $indicativeOfReplicaRuntime = $this->affectedRows() > self::SMALL_WRITE_ROWS;
 970                         } elseif ( $verb === 'REPLACE' ) {
 971                                 $indicativeOfReplicaRuntime = $this->affectedRows() > self::SMALL_WRITE_ROWS / 2;
 972                         }
 973                 }
 974
 975                 $this->mTrxWriteDuration += $runtime;
 976                 $this->mTrxWriteQueryCount += 1;
 977                 if ( $indicativeOfReplicaRuntime ) {
 978                         $this->mTrxWriteAdjDuration += $runtime;
 979                         $this->mTrxWriteAdjQueryCount += 1;
 980                 }
 981         }
 982
 983         private function canRecoverFromDisconnect( $sql, $priorWritesPending ) {
 984                 # Transaction dropped; this can mean lost writes, or REPEATABLE-READ snapshots.
 985                 # Dropped connections also mean that named locks are automatically released.
 986                 # Only allow error suppression in autocommit mode or when the lost transaction
 987                 # didn't matter anyway (aside from DBO_TRX snapshot loss).
 988                 if ( $this->mNamedLocksHeld ) {
 989                         return false; // possible critical section violation
 990                 } elseif ( $sql === 'COMMIT' ) {
 991                         return !$priorWritesPending; // nothing written anyway? (T127428)
 992                 } elseif ( $sql === 'ROLLBACK' ) {
 993                         return true; // transaction lost...which is also what was requested :)
 994                 } elseif ( $this->explicitTrxActive() ) {
 995                         return false; // don't drop atomocity
 996                 } elseif ( $priorWritesPending ) {
 997                         return false; // prior writes lost from implicit transaction
 998                 }
 999
1000                 return true;
1001         }
1002
1003         private function handleSessionLoss() {
1004                 $this->mTrxLevel = 0;
1005                 $this->mTrxIdleCallbacks = []; // bug 65263
1006                 $this->mTrxPreCommitCallbacks = []; // bug 65263
1007                 $this->mSessionTempTables = [];
1008                 $this->mNamedLocksHeld = [];
1009                 try {
1010                         // Handle callbacks in mTrxEndCallbacks
1011                         $this->runOnTransactionIdleCallbacks( self::TRIGGER_ROLLBACK );
1012                         $this->runTransactionListenerCallbacks( self::TRIGGER_ROLLBACK );
1013                         return null;
1014                 } catch ( Exception $e ) {
1015                         // Already logged; move on...
1016                         return $e;
1017                 }
1018         }
1019
1020         public function reportQueryError( $error, $errno, $sql, $fname, $tempIgnore = false ) {
1021                 if ( $this->ignoreErrors() || $tempIgnore ) {
1022                         $this->queryLogger->debug( "SQL ERROR (ignored): $error\n" );
1023                 } else {
1024                         $sql1line = mb_substr( str_replace( "\n", "\\n", $sql ), 0, 5 * 1024 );
1025                         $this->queryLogger->error(
1026                                 "{fname}\t{db_server}\t{errno}\t{error}\t{sql1line}",
1027                                 $this->getLogContext( [
1028                                         'method' => __METHOD__,
1029                                         'errno' => $errno,
1030                                         'error' => $error,
1031                                         'sql1line' => $sql1line,
1032                                         'fname' => $fname,
1033                                 ] )
1034                         );
1035                         $this->queryLogger->debug( "SQL ERROR: " . $error . "\n" );
1036                         throw new DBQueryError( $this, $error, $errno, $sql, $fname );
1037                 }
1038         }
1039
1040         public function freeResult( $res ) {
1041         }
1042
1043         public function selectField(
1044                 $table, $var, $cond = '', $fname = __METHOD__, $options = []
1045         ) {
1046                 if ( $var === '*' ) { // sanity
1047                         throw new DBUnexpectedError( $this, "Cannot use a * field: got '$var'" );
1048                 }
1049
1050                 if ( !is_array( $options ) ) {
1051                         $options = [ $options ];
1052                 }
1053
1054                 $options['LIMIT'] = 1;
1055
1056                 $res = $this->select( $table, $var, $cond, $fname, $options );
1057                 if ( $res === false || !$this->numRows( $res ) ) {
1058                         return false;
1059                 }
1060
1061                 $row = $this->fetchRow( $res );
1062
1063                 if ( $row !== false ) {
1064                         return reset( $row );
1065                 } else {
1066                         return false;
1067                 }
1068         }
1069
1070         public function selectFieldValues(
1071                 $table, $var, $cond = '', $fname = __METHOD__, $options = [], $join_conds = []
1072         ) {
1073                 if ( $var === '*' ) { // sanity
1074                         throw new DBUnexpectedError( $this, "Cannot use a * field" );
1075                 } elseif ( !is_string( $var ) ) { // sanity
1076                         throw new DBUnexpectedError( $this, "Cannot use an array of fields" );
1077                 }
1078
1079                 if ( !is_array( $options ) ) {
1080                         $options = [ $options ];
1081                 }
1082
1083                 $res = $this->select( $table, $var, $cond, $fname, $options, $join_conds );
1084                 if ( $res === false ) {
1085                         return false;
1086                 }
1087
1088                 $values = [];
1089                 foreach ( $res as $row ) {
1090                         $values[] = $row->$var;
1091                 }
1092
1093                 return $values;
1094         }
1095
1096         /**
1097          * Returns an optional USE INDEX clause to go after the table, and a
1098          * string to go at the end of the query.
1099          *
1100          * @param array $options Associative array of options to be turned into
1101          *   an SQL query, valid keys are listed in the function.
1102          * @return array
1103          * @see DatabaseBase::select()
1104          */
1105         protected function makeSelectOptions( $options ) {
1106                 $preLimitTail = $postLimitTail = '';
1107                 $startOpts = '';
1108
1109                 $noKeyOptions = [];
1110
1111                 foreach ( $options as $key => $option ) {
1112                         if ( is_numeric( $key ) ) {
1113                                 $noKeyOptions[$option] = true;
1114                         }
1115                 }
1116
1117                 $preLimitTail .= $this->makeGroupByWithHaving( $options );
1118
1119                 $preLimitTail .= $this->makeOrderBy( $options );
1120
1121                 // if (isset($options['LIMIT'])) {
1122                 //      $tailOpts .= $this->limitResult('', $options['LIMIT'],
1123                 //              isset($options['OFFSET']) ? $options['OFFSET']
1124                 //              : false);
1125                 // }
1126
1127                 if ( isset( $noKeyOptions['FOR UPDATE'] ) ) {
1128                         $postLimitTail .= ' FOR UPDATE';
1129                 }
1130
1131                 if ( isset( $noKeyOptions['LOCK IN SHARE MODE'] ) ) {
1132                         $postLimitTail .= ' LOCK IN SHARE MODE';
1133                 }
1134
1135                 if ( isset( $noKeyOptions['DISTINCT'] ) || isset( $noKeyOptions['DISTINCTROW'] ) ) {
1136                         $startOpts .= 'DISTINCT';
1137                 }
1138
1139                 # Various MySQL extensions
1140                 if ( isset( $noKeyOptions['STRAIGHT_JOIN'] ) ) {
1141                         $startOpts .= ' /*! STRAIGHT_JOIN */';
1142                 }
1143
1144                 if ( isset( $noKeyOptions['HIGH_PRIORITY'] ) ) {
1145                         $startOpts .= ' HIGH_PRIORITY';
1146                 }
1147
1148                 if ( isset( $noKeyOptions['SQL_BIG_RESULT'] ) ) {
1149                         $startOpts .= ' SQL_BIG_RESULT';
1150                 }
1151
1152                 if ( isset( $noKeyOptions['SQL_BUFFER_RESULT'] ) ) {
1153                         $startOpts .= ' SQL_BUFFER_RESULT';
1154                 }
1155
1156                 if ( isset( $noKeyOptions['SQL_SMALL_RESULT'] ) ) {
1157                         $startOpts .= ' SQL_SMALL_RESULT';
1158                 }
1159
1160                 if ( isset( $noKeyOptions['SQL_CALC_FOUND_ROWS'] ) ) {
1161                         $startOpts .= ' SQL_CALC_FOUND_ROWS';
1162                 }
1163
1164                 if ( isset( $noKeyOptions['SQL_CACHE'] ) ) {
1165                         $startOpts .= ' SQL_CACHE';
1166                 }
1167
1168                 if ( isset( $noKeyOptions['SQL_NO_CACHE'] ) ) {
1169                         $startOpts .= ' SQL_NO_CACHE';
1170                 }
1171
1172                 if ( isset( $options['USE INDEX'] ) && is_string( $options['USE INDEX'] ) ) {
1173                         $useIndex = $this->useIndexClause( $options['USE INDEX'] );
1174                 } else {
1175                         $useIndex = '';
1176                 }
1177                 if ( isset( $options['IGNORE INDEX'] ) && is_string( $options['IGNORE INDEX'] ) ) {
1178                         $ignoreIndex = $this->ignoreIndexClause( $options['IGNORE INDEX'] );
1179                 } else {
1180                         $ignoreIndex = '';
1181                 }
1182
1183                 return [ $startOpts, $useIndex, $preLimitTail, $postLimitTail, $ignoreIndex ];
1184         }
1185
1186         /**
1187          * Returns an optional GROUP BY with an optional HAVING
1188          *
1189          * @param array $options Associative array of options
1190          * @return string
1191          * @see DatabaseBase::select()
1192          * @since 1.21
1193          */
1194         protected function makeGroupByWithHaving( $options ) {
1195                 $sql = '';
1196                 if ( isset( $options['GROUP BY'] ) ) {
1197                         $gb = is_array( $options['GROUP BY'] )
1198                                 ? implode( ',', $options['GROUP BY'] )
1199                                 : $options['GROUP BY'];
1200                         $sql .= ' GROUP BY ' . $gb;
1201                 }
1202                 if ( isset( $options['HAVING'] ) ) {
1203                         $having = is_array( $options['HAVING'] )
1204                                 ? $this->makeList( $options['HAVING'], self::LIST_AND )
1205                                 : $options['HAVING'];
1206                         $sql .= ' HAVING ' . $having;
1207                 }
1208
1209                 return $sql;
1210         }
1211
1212         /**
1213          * Returns an optional ORDER BY
1214          *
1215          * @param array $options Associative array of options
1216          * @return string
1217          * @see DatabaseBase::select()
1218          * @since 1.21
1219          */
1220         protected function makeOrderBy( $options ) {
1221                 if ( isset( $options['ORDER BY'] ) ) {
1222                         $ob = is_array( $options['ORDER BY'] )
1223                                 ? implode( ',', $options['ORDER BY'] )
1224                                 : $options['ORDER BY'];
1225
1226                         return ' ORDER BY ' . $ob;
1227                 }
1228
1229                 return '';
1230         }
1231
1232         // See IDatabase::select for the docs for this function
1233         public function select( $table, $vars, $conds = '', $fname = __METHOD__,
1234                 $options = [], $join_conds = [] ) {
1235                 $sql = $this->selectSQLText( $table, $vars, $conds, $fname, $options, $join_conds );
1236
1237                 return $this->query( $sql, $fname );
1238         }
1239
1240         public function selectSQLText( $table, $vars, $conds = '', $fname = __METHOD__,
1241                 $options = [], $join_conds = []
1242         ) {
1243                 if ( is_array( $vars ) ) {
1244                         $vars = implode( ',', $this->fieldNamesWithAlias( $vars ) );
1245                 }
1246
1247                 $options = (array)$options;
1248                 $useIndexes = ( isset( $options['USE INDEX'] ) && is_array( $options['USE INDEX'] ) )
1249                         ? $options['USE INDEX']
1250                         : [];
1251                 $ignoreIndexes = ( isset( $options['IGNORE INDEX'] ) && is_array( $options['IGNORE INDEX'] ) )
1252                         ? $options['IGNORE INDEX']
1253                         : [];
1254
1255                 if ( is_array( $table ) ) {
1256                         $from = ' FROM ' .
1257                                 $this->tableNamesWithIndexClauseOrJOIN( $table, $useIndexes, $ignoreIndexes, $join_conds );
1258                 } elseif ( $table != '' ) {
1259                         if ( $table[0] == ' ' ) {
1260                                 $from = ' FROM ' . $table;
1261                         } else {
1262                                 $from = ' FROM ' .
1263                                         $this->tableNamesWithIndexClauseOrJOIN( [ $table ], $useIndexes, $ignoreIndexes, [] );
1264                         }
1265                 } else {
1266                         $from = '';
1267                 }
1268
1269                 list( $startOpts, $useIndex, $preLimitTail, $postLimitTail, $ignoreIndex ) =
1270                         $this->makeSelectOptions( $options );
1271
1272                 if ( !empty( $conds ) ) {
1273                         if ( is_array( $conds ) ) {
1274                                 $conds = $this->makeList( $conds, self::LIST_AND );
1275                         }
1276                         $sql = "SELECT $startOpts $vars $from $useIndex $ignoreIndex WHERE $conds $preLimitTail";
1277                 } else {
1278                         $sql = "SELECT $startOpts $vars $from $useIndex $ignoreIndex $preLimitTail";
1279                 }
1280
1281                 if ( isset( $options['LIMIT'] ) ) {
1282                         $sql = $this->limitResult( $sql, $options['LIMIT'],
1283                                 isset( $options['OFFSET'] ) ? $options['OFFSET'] : false );
1284                 }
1285                 $sql = "$sql $postLimitTail";
1286
1287                 if ( isset( $options['EXPLAIN'] ) ) {
1288                         $sql = 'EXPLAIN ' . $sql;
1289                 }
1290
1291                 return $sql;
1292         }
1293
1294         public function selectRow( $table, $vars, $conds, $fname = __METHOD__,
1295                 $options = [], $join_conds = []
1296         ) {
1297                 $options = (array)$options;
1298                 $options['LIMIT'] = 1;
1299                 $res = $this->select( $table, $vars, $conds, $fname, $options, $join_conds );
1300
1301                 if ( $res === false ) {
1302                         return false;
1303                 }
1304
1305                 if ( !$this->numRows( $res ) ) {
1306                         return false;
1307                 }
1308
1309                 $obj = $this->fetchObject( $res );
1310
1311                 return $obj;
1312         }
1313
1314         public function estimateRowCount(
1315                 $table, $vars = '*', $conds = '', $fname = __METHOD__, $options = []
1316         ) {
1317                 $rows = 0;
1318                 $res = $this->select( $table, [ 'rowcount' => 'COUNT(*)' ], $conds, $fname, $options );
1319
1320                 if ( $res ) {
1321                         $row = $this->fetchRow( $res );
1322                         $rows = ( isset( $row['rowcount'] ) ) ? (int)$row['rowcount'] : 0;
1323                 }
1324
1325                 return $rows;
1326         }
1327
1328         public function selectRowCount(
1329                 $tables, $vars = '*', $conds = '', $fname = __METHOD__, $options = [], $join_conds = []
1330         ) {
1331                 $rows = 0;
1332                 $sql = $this->selectSQLText( $tables, '1', $conds, $fname, $options, $join_conds );
1333                 $res = $this->query( "SELECT COUNT(*) AS rowcount FROM ($sql) tmp_count", $fname );
1334
1335                 if ( $res ) {
1336                         $row = $this->fetchRow( $res );
1337                         $rows = ( isset( $row['rowcount'] ) ) ? (int)$row['rowcount'] : 0;
1338                 }
1339
1340                 return $rows;
1341         }
1342
1343         /**
1344          * Removes most variables from an SQL query and replaces them with X or N for numbers.
1345          * It's only slightly flawed. Don't use for anything important.
1346          *
1347          * @param string $sql A SQL Query
1348          *
1349          * @return string
1350          */
1351         protected static function generalizeSQL( $sql ) {
1352                 # This does the same as the regexp below would do, but in such a way
1353                 # as to avoid crashing php on some large strings.
1354                 # $sql = preg_replace( "/'([^\\\\']|\\\\.)*'|\"([^\\\\\"]|\\\\.)*\"/", "'X'", $sql );
1355
1356                 $sql = str_replace( "\\\\", '', $sql );
1357                 $sql = str_replace( "\\'", '', $sql );
1358                 $sql = str_replace( "\\\"", '', $sql );
1359                 $sql = preg_replace( "/'.*'/s", "'X'", $sql );
1360                 $sql = preg_replace( '/".*"/s', "'X'", $sql );
1361
1362                 # All newlines, tabs, etc replaced by single space
1363                 $sql = preg_replace( '/\s+/', ' ', $sql );
1364
1365                 # All numbers => N,
1366                 # except the ones surrounded by characters, e.g. l10n
1367                 $sql = preg_replace( '/-?\d+(,-?\d+)+/s', 'N,...,N', $sql );
1368                 $sql = preg_replace( '/(?<![a-zA-Z])-?\d+(?![a-zA-Z])/s', 'N', $sql );
1369
1370                 return $sql;
1371         }
1372
1373         public function fieldExists( $table, $field, $fname = __METHOD__ ) {
1374                 $info = $this->fieldInfo( $table, $field );
1375
1376                 return (bool)$info;
1377         }
1378
1379         public function indexExists( $table, $index, $fname = __METHOD__ ) {
1380                 if ( !$this->tableExists( $table ) ) {
1381                         return null;
1382                 }
1383
1384                 $info = $this->indexInfo( $table, $index, $fname );
1385                 if ( is_null( $info ) ) {
1386                         return null;
1387                 } else {
1388                         return $info !== false;
1389                 }
1390         }
1391
1392         public function tableExists( $table, $fname = __METHOD__ ) {
1393                 $tableRaw = $this->tableName( $table, 'raw' );
1394                 if ( isset( $this->mSessionTempTables[$tableRaw] ) ) {
1395                         return true; // already known to exist
1396                 }
1397
1398                 $table = $this->tableName( $table );
1399                 $old = $this->ignoreErrors( true );
1400                 $res = $this->query( "SELECT 1 FROM $table LIMIT 1", $fname );
1401                 $this->ignoreErrors( $old );
1402
1403                 return (bool)$res;
1404         }
1405
1406         public function indexUnique( $table, $index ) {
1407                 $indexInfo = $this->indexInfo( $table, $index );
1408
1409                 if ( !$indexInfo ) {
1410                         return null;
1411                 }
1412
1413                 return !$indexInfo[0]->Non_unique;
1414         }
1415
1416         /**
1417          * Helper for DatabaseBase::insert().
1418          *
1419          * @param array $options
1420          * @return string
1421          */
1422         protected function makeInsertOptions( $options ) {
1423                 return implode( ' ', $options );
1424         }
1425
1426         public function insert( $table, $a, $fname = __METHOD__, $options = [] ) {
1427                 # No rows to insert, easy just return now
1428                 if ( !count( $a ) ) {
1429                         return true;
1430                 }
1431
1432                 $table = $this->tableName( $table );
1433
1434                 if ( !is_array( $options ) ) {
1435                         $options = [ $options ];
1436                 }
1437
1438                 $fh = null;
1439                 if ( isset( $options['fileHandle'] ) ) {
1440                         $fh = $options['fileHandle'];
1441                 }
1442                 $options = $this->makeInsertOptions( $options );
1443
1444                 if ( isset( $a[0] ) && is_array( $a[0] ) ) {
1445                         $multi = true;
1446                         $keys = array_keys( $a[0] );
1447                 } else {
1448                         $multi = false;
1449                         $keys = array_keys( $a );
1450                 }
1451
1452                 $sql = 'INSERT ' . $options .
1453                         " INTO $table (" . implode( ',', $keys ) . ') VALUES ';
1454
1455                 if ( $multi ) {
1456                         $first = true;
1457                         foreach ( $a as $row ) {
1458                                 if ( $first ) {
1459                                         $first = false;
1460                                 } else {
1461                                         $sql .= ',';
1462                                 }
1463                                 $sql .= '(' . $this->makeList( $row ) . ')';
1464                         }
1465                 } else {
1466                         $sql .= '(' . $this->makeList( $a ) . ')';
1467                 }
1468
1469                 if ( $fh !== null && false === fwrite( $fh, $sql ) ) {
1470                         return false;
1471                 } elseif ( $fh !== null ) {
1472                         return true;
1473                 }
1474
1475                 return (bool)$this->query( $sql, $fname );
1476         }
1477
1478         /**
1479          * Make UPDATE options array for DatabaseBase::makeUpdateOptions
1480          *
1481          * @param array $options
1482          * @return array
1483          */
1484         protected function makeUpdateOptionsArray( $options ) {
1485                 if ( !is_array( $options ) ) {
1486                         $options = [ $options ];
1487                 }
1488
1489                 $opts = [];
1490
1491                 if ( in_array( 'IGNORE', $options ) ) {
1492                         $opts[] = 'IGNORE';
1493                 }
1494
1495                 return $opts;
1496         }
1497
1498         /**
1499          * Make UPDATE options for the DatabaseBase::update function
1500          *
1501          * @param array $options The options passed to DatabaseBase::update
1502          * @return string
1503          */
1504         protected function makeUpdateOptions( $options ) {
1505                 $opts = $this->makeUpdateOptionsArray( $options );
1506
1507                 return implode( ' ', $opts );
1508         }
1509
1510         public function update( $table, $values, $conds, $fname = __METHOD__, $options = [] ) {
1511                 $table = $this->tableName( $table );
1512                 $opts = $this->makeUpdateOptions( $options );
1513                 $sql = "UPDATE $opts $table SET " . $this->makeList( $values, self::LIST_SET );
1514
1515                 if ( $conds !== [] && $conds !== '*' ) {
1516                         $sql .= " WHERE " . $this->makeList( $conds, self::LIST_AND );
1517                 }
1518
1519                 return $this->query( $sql, $fname );
1520         }
1521
1522         public function makeList( $a, $mode = self::LIST_COMMA ) {
1523                 if ( !is_array( $a ) ) {
1524                         throw new DBUnexpectedError( $this, __METHOD__ . ' called with incorrect parameters' );
1525                 }
1526
1527                 $first = true;
1528                 $list = '';
1529
1530                 foreach ( $a as $field => $value ) {
1531                         if ( !$first ) {
1532                                 if ( $mode == self::LIST_AND ) {
1533                                         $list .= ' AND ';
1534                                 } elseif ( $mode == self::LIST_OR ) {
1535                                         $list .= ' OR ';
1536                                 } else {
1537                                         $list .= ',';
1538                                 }
1539                         } else {
1540                                 $first = false;
1541                         }
1542
1543                         if ( ( $mode == self::LIST_AND || $mode == self::LIST_OR ) && is_numeric( $field ) ) {
1544                                 $list .= "($value)";
1545                         } elseif ( $mode == self::LIST_SET && is_numeric( $field ) ) {
1546                                 $list .= "$value";
1547                         } elseif (
1548                                 ( $mode == self::LIST_AND || $mode == self::LIST_OR ) && is_array( $value )
1549                         ) {
1550                                 // Remove null from array to be handled separately if found
1551                                 $includeNull = false;
1552                                 foreach ( array_keys( $value, null, true ) as $nullKey ) {
1553                                         $includeNull = true;
1554                                         unset( $value[$nullKey] );
1555                                 }
1556                                 if ( count( $value ) == 0 && !$includeNull ) {
1557                                         throw new InvalidArgumentException(
1558                                                 __METHOD__ . ": empty input for field $field" );
1559                                 } elseif ( count( $value ) == 0 ) {
1560                                         // only check if $field is null
1561                                         $list .= "$field IS NULL";
1562                                 } else {
1563                                         // IN clause contains at least one valid element
1564                                         if ( $includeNull ) {
1565                                                 // Group subconditions to ensure correct precedence
1566                                                 $list .= '(';
1567                                         }
1568                                         if ( count( $value ) == 1 ) {
1569                                                 // Special-case single values, as IN isn't terribly efficient
1570                                                 // Don't necessarily assume the single key is 0; we don't
1571                                                 // enforce linear numeric ordering on other arrays here.
1572                                                 $value = array_values( $value )[0];
1573                                                 $list .= $field . " = " . $this->addQuotes( $value );
1574                                         } else {
1575                                                 $list .= $field . " IN (" . $this->makeList( $value ) . ") ";
1576                                         }
1577                                         // if null present in array, append IS NULL
1578                                         if ( $includeNull ) {
1579                                                 $list .= " OR $field IS NULL)";
1580                                         }
1581                                 }
1582                         } elseif ( $value === null ) {
1583                                 if ( $mode == self::LIST_AND || $mode == self::LIST_OR ) {
1584                                         $list .= "$field IS ";
1585                                 } elseif ( $mode == self::LIST_SET ) {
1586                                         $list .= "$field = ";
1587                                 }
1588                                 $list .= 'NULL';
1589                         } else {
1590                                 if (
1591                                         $mode == self::LIST_AND || $mode == self::LIST_OR || $mode == self::LIST_SET
1592                                 ) {
1593                                         $list .= "$field = ";
1594                                 }
1595                                 $list .= $mode == self::LIST_NAMES ? $value : $this->addQuotes( $value );
1596                         }
1597                 }
1598
1599                 return $list;
1600         }
1601
1602         public function makeWhereFrom2d( $data, $baseKey, $subKey ) {
1603                 $conds = [];
1604
1605                 foreach ( $data as $base => $sub ) {
1606                         if ( count( $sub ) ) {
1607                                 $conds[] = $this->makeList(
1608                                         [ $baseKey => $base, $subKey => array_keys( $sub ) ],
1609                                         self::LIST_AND );
1610                         }
1611                 }
1612
1613                 if ( $conds ) {
1614                         return $this->makeList( $conds, self::LIST_OR );
1615                 } else {
1616                         // Nothing to search for...
1617                         return false;
1618                 }
1619         }
1620
1621         public function aggregateValue( $valuedata, $valuename = 'value' ) {
1622                 return $valuename;
1623         }
1624
1625         public function bitNot( $field ) {
1626                 return "(~$field)";
1627         }
1628
1629         public function bitAnd( $fieldLeft, $fieldRight ) {
1630                 return "($fieldLeft & $fieldRight)";
1631         }
1632
1633         public function bitOr( $fieldLeft, $fieldRight ) {
1634                 return "($fieldLeft | $fieldRight)";
1635         }
1636
1637         public function buildConcat( $stringList ) {
1638                 return 'CONCAT(' . implode( ',', $stringList ) . ')';
1639         }
1640
1641         public function buildGroupConcatField(
1642                 $delim, $table, $field, $conds = '', $join_conds = []
1643         ) {
1644                 $fld = "GROUP_CONCAT($field SEPARATOR " . $this->addQuotes( $delim ) . ')';
1645
1646                 return '(' . $this->selectSQLText( $table, $fld, $conds, null, [], $join_conds ) . ')';
1647         }
1648
1649         public function buildStringCast( $field ) {
1650                 return $field;
1651         }
1652
1653         public function selectDB( $db ) {
1654                 # Stub. Shouldn't cause serious problems if it's not overridden, but
1655                 # if your database engine supports a concept similar to MySQL's
1656                 # databases you may as well.
1657                 $this->mDBname = $db;
1658
1659                 return true;
1660         }
1661
1662         public function getDBname() {
1663                 return $this->mDBname;
1664         }
1665
1666         public function getServer() {
1667                 return $this->mServer;
1668         }
1669
1670         /**
1671          * Format a table name ready for use in constructing an SQL query
1672          *
1673          * This does two important things: it quotes the table names to clean them up,
1674          * and it adds a table prefix if only given a table name with no quotes.
1675          *
1676          * All functions of this object which require a table name call this function
1677          * themselves. Pass the canonical name to such functions. This is only needed
1678          * when calling query() directly.
1679          *
1680          * @note This function does not sanitize user input. It is not safe to use
1681          *   this function to escape user input.
1682          * @param string $name Database table name
1683          * @param string $format One of:
1684          *   quoted - Automatically pass the table name through addIdentifierQuotes()
1685          *            so that it can be used in a query.
1686          *   raw - Do not add identifier quotes to the table name
1687          * @return string Full database name
1688          */
1689         public function tableName( $name, $format = 'quoted' ) {
1690                 # Skip the entire process when we have a string quoted on both ends.
1691                 # Note that we check the end so that we will still quote any use of
1692                 # use of `database`.table. But won't break things if someone wants
1693                 # to query a database table with a dot in the name.
1694                 if ( $this->isQuotedIdentifier( $name ) ) {
1695                         return $name;
1696                 }
1697
1698                 # Lets test for any bits of text that should never show up in a table
1699                 # name. Basically anything like JOIN or ON which are actually part of
1700                 # SQL queries, but may end up inside of the table value to combine
1701                 # sql. Such as how the API is doing.
1702                 # Note that we use a whitespace test rather than a \b test to avoid
1703                 # any remote case where a word like on may be inside of a table name
1704                 # surrounded by symbols which may be considered word breaks.
1705                 if ( preg_match( '/(^|\s)(DISTINCT|JOIN|ON|AS)(\s|$)/i', $name ) !== 0 ) {
1706                         return $name;
1707                 }
1708
1709                 # Split database and table into proper variables.
1710                 # We reverse the explode so that database.table and table both output
1711                 # the correct table.
1712                 $dbDetails = explode( '.', $name, 3 );
1713                 if ( count( $dbDetails ) == 3 ) {
1714                         list( $database, $schema, $table ) = $dbDetails;
1715                         # We don't want any prefix added in this case
1716                         $prefix = '';
1717                 } elseif ( count( $dbDetails ) == 2 ) {
1718                         list( $database, $table ) = $dbDetails;
1719                         # We don't want any prefix added in this case
1720                         # In dbs that support it, $database may actually be the schema
1721                         # but that doesn't affect any of the functionality here
1722                         $prefix = '';
1723                         $schema = '';
1724                 } else {
1725                         list( $table ) = $dbDetails;
1726                         if ( isset( $this->tableAliases[$table] ) ) {
1727                                 $database = $this->tableAliases[$table]['dbname'];
1728                                 $schema = is_string( $this->tableAliases[$table]['schema'] )
1729                                         ? $this->tableAliases[$table]['schema']
1730                                         : $this->mSchema;
1731                                 $prefix = is_string( $this->tableAliases[$table]['prefix'] )
1732                                         ? $this->tableAliases[$table]['prefix']
1733                                         : $this->mTablePrefix;
1734                         } else {
1735                                 $database = '';
1736                                 $schema = $this->mSchema; # Default schema
1737                                 $prefix = $this->mTablePrefix; # Default prefix
1738                         }
1739                 }
1740
1741                 # Quote $table and apply the prefix if not quoted.
1742                 # $tableName might be empty if this is called from Database::replaceVars()
1743                 $tableName = "{$prefix}{$table}";
1744                 if ( $format == 'quoted'
1745                         && !$this->isQuotedIdentifier( $tableName ) && $tableName !== ''
1746                 ) {
1747                         $tableName = $this->addIdentifierQuotes( $tableName );
1748                 }
1749
1750                 # Quote $schema and merge it with the table name if needed
1751                 if ( strlen( $schema ) ) {
1752                         if ( $format == 'quoted' && !$this->isQuotedIdentifier( $schema ) ) {
1753                                 $schema = $this->addIdentifierQuotes( $schema );
1754                         }
1755                         $tableName = $schema . '.' . $tableName;
1756                 }
1757
1758                 # Quote $database and merge it with the table name if needed
1759                 if ( $database !== '' ) {
1760                         if ( $format == 'quoted' && !$this->isQuotedIdentifier( $database ) ) {
1761                                 $database = $this->addIdentifierQuotes( $database );
1762                         }
1763                         $tableName = $database . '.' . $tableName;
1764                 }
1765
1766                 return $tableName;
1767         }
1768
1769         /**
1770          * Fetch a number of table names into an array
1771          * This is handy when you need to construct SQL for joins
1772          *
1773          * Example:
1774          * extract( $dbr->tableNames( 'user', 'watchlist' ) );
1775          * $sql = "SELECT wl_namespace,wl_title FROM $watchlist,$user
1776          *         WHERE wl_user=user_id AND wl_user=$nameWithQuotes";
1777          *
1778          * @return array
1779          */
1780         public function tableNames() {
1781                 $inArray = func_get_args();
1782                 $retVal = [];
1783
1784                 foreach ( $inArray as $name ) {
1785                         $retVal[$name] = $this->tableName( $name );
1786                 }
1787
1788                 return $retVal;
1789         }
1790
1791         /**
1792          * Fetch a number of table names into an zero-indexed numerical array
1793          * This is handy when you need to construct SQL for joins
1794          *
1795          * Example:
1796          * list( $user, $watchlist ) = $dbr->tableNamesN( 'user', 'watchlist' );
1797          * $sql = "SELECT wl_namespace,wl_title FROM $watchlist,$user
1798          *         WHERE wl_user=user_id AND wl_user=$nameWithQuotes";
1799          *
1800          * @return array
1801          */
1802         public function tableNamesN() {
1803                 $inArray = func_get_args();
1804                 $retVal = [];
1805
1806                 foreach ( $inArray as $name ) {
1807                         $retVal[] = $this->tableName( $name );
1808                 }
1809
1810                 return $retVal;
1811         }
1812
1813         /**
1814          * Get an aliased table name
1815          * e.g. tableName AS newTableName
1816          *
1817          * @param string $name Table name, see tableName()
1818          * @param string|bool $alias Alias (optional)
1819          * @return string SQL name for aliased table. Will not alias a table to its own name
1820          */
1821         protected function tableNameWithAlias( $name, $alias = false ) {
1822                 if ( !$alias || $alias == $name ) {
1823                         return $this->tableName( $name );
1824                 } else {
1825                         return $this->tableName( $name ) . ' ' . $this->addIdentifierQuotes( $alias );
1826                 }
1827         }
1828
1829         /**
1830          * Gets an array of aliased table names
1831          *
1832          * @param array $tables [ [alias] => table ]
1833          * @return string[] See tableNameWithAlias()
1834          */
1835         protected function tableNamesWithAlias( $tables ) {
1836                 $retval = [];
1837                 foreach ( $tables as $alias => $table ) {
1838                         if ( is_numeric( $alias ) ) {
1839                                 $alias = $table;
1840                         }
1841                         $retval[] = $this->tableNameWithAlias( $table, $alias );
1842                 }
1843
1844                 return $retval;
1845         }
1846
1847         /**
1848          * Get an aliased field name
1849          * e.g. fieldName AS newFieldName
1850          *
1851          * @param string $name Field name
1852          * @param string|bool $alias Alias (optional)
1853          * @return string SQL name for aliased field. Will not alias a field to its own name
1854          */
1855         protected function fieldNameWithAlias( $name, $alias = false ) {
1856                 if ( !$alias || (string)$alias === (string)$name ) {
1857                         return $name;
1858                 } else {
1859                         return $name . ' AS ' . $this->addIdentifierQuotes( $alias ); // PostgreSQL needs AS
1860                 }
1861         }
1862
1863         /**
1864          * Gets an array of aliased field names
1865          *
1866          * @param array $fields [ [alias] => field ]
1867          * @return string[] See fieldNameWithAlias()
1868          */
1869         protected function fieldNamesWithAlias( $fields ) {
1870                 $retval = [];
1871                 foreach ( $fields as $alias => $field ) {
1872                         if ( is_numeric( $alias ) ) {
1873                                 $alias = $field;
1874                         }
1875                         $retval[] = $this->fieldNameWithAlias( $field, $alias );
1876                 }
1877
1878                 return $retval;
1879         }
1880
1881         /**
1882          * Get the aliased table name clause for a FROM clause
1883          * which might have a JOIN and/or USE INDEX or IGNORE INDEX clause
1884          *
1885          * @param array $tables ( [alias] => table )
1886          * @param array $use_index Same as for select()
1887          * @param array $ignore_index Same as for select()
1888          * @param array $join_conds Same as for select()
1889          * @return string
1890          */
1891         protected function tableNamesWithIndexClauseOrJOIN(
1892                 $tables, $use_index = [], $ignore_index = [], $join_conds = []
1893         ) {
1894                 $ret = [];
1895                 $retJOIN = [];
1896                 $use_index = (array)$use_index;
1897                 $ignore_index = (array)$ignore_index;
1898                 $join_conds = (array)$join_conds;
1899
1900                 foreach ( $tables as $alias => $table ) {
1901                         if ( !is_string( $alias ) ) {
1902                                 // No alias? Set it equal to the table name
1903                                 $alias = $table;
1904                         }
1905                         // Is there a JOIN clause for this table?
1906                         if ( isset( $join_conds[$alias] ) ) {
1907                                 list( $joinType, $conds ) = $join_conds[$alias];
1908                                 $tableClause = $joinType;
1909                                 $tableClause .= ' ' . $this->tableNameWithAlias( $table, $alias );
1910                                 if ( isset( $use_index[$alias] ) ) { // has USE INDEX?
1911                                         $use = $this->useIndexClause( implode( ',', (array)$use_index[$alias] ) );
1912                                         if ( $use != '' ) {
1913                                                 $tableClause .= ' ' . $use;
1914                                         }
1915                                 }
1916                                 if ( isset( $ignore_index[$alias] ) ) { // has IGNORE INDEX?
1917                                         $ignore = $this->ignoreIndexClause( implode( ',', (array)$ignore_index[$alias] ) );
1918                                         if ( $ignore != '' ) {
1919                                                 $tableClause .= ' ' . $ignore;
1920                                         }
1921                                 }
1922                                 $on = $this->makeList( (array)$conds, self::LIST_AND );
1923                                 if ( $on != '' ) {
1924                                         $tableClause .= ' ON (' . $on . ')';
1925                                 }
1926
1927                                 $retJOIN[] = $tableClause;
1928                         } elseif ( isset( $use_index[$alias] ) ) {
1929                                 // Is there an INDEX clause for this table?
1930                                 $tableClause = $this->tableNameWithAlias( $table, $alias );
1931                                 $tableClause .= ' ' . $this->useIndexClause(
1932                                                 implode( ',', (array)$use_index[$alias] )
1933                                         );
1934
1935                                 $ret[] = $tableClause;
1936                         } elseif ( isset( $ignore_index[$alias] ) ) {
1937                                 // Is there an INDEX clause for this table?
1938                                 $tableClause = $this->tableNameWithAlias( $table, $alias );
1939                                 $tableClause .= ' ' . $this->ignoreIndexClause(
1940                                                 implode( ',', (array)$ignore_index[$alias] )
1941                                         );
1942
1943                                 $ret[] = $tableClause;
1944                         } else {
1945                                 $tableClause = $this->tableNameWithAlias( $table, $alias );
1946
1947                                 $ret[] = $tableClause;
1948                         }
1949                 }
1950
1951                 // We can't separate explicit JOIN clauses with ',', use ' ' for those
1952                 $implicitJoins = !empty( $ret ) ? implode( ',', $ret ) : "";
1953                 $explicitJoins = !empty( $retJOIN ) ? implode( ' ', $retJOIN ) : "";
1954
1955                 // Compile our final table clause
1956                 return implode( ' ', [ $implicitJoins, $explicitJoins ] );
1957         }
1958
1959         /**
1960          * Get the name of an index in a given table.
1961          *
1962          * @param string $index
1963          * @return string
1964          */
1965         protected function indexName( $index ) {
1966                 // Backwards-compatibility hack
1967                 $renamed = [
1968                         'ar_usertext_timestamp' => 'usertext_timestamp',
1969                         'un_user_id' => 'user_id',
1970                         'un_user_ip' => 'user_ip',
1971                 ];
1972
1973                 if ( isset( $renamed[$index] ) ) {
1974                         return $renamed[$index];
1975                 } else {
1976                         return $index;
1977                 }
1978         }
1979
1980         public function addQuotes( $s ) {
1981                 if ( $s instanceof Blob ) {
1982                         $s = $s->fetch();
1983                 }
1984                 if ( $s === null ) {
1985                         return 'NULL';
1986                 } elseif ( is_bool( $s ) ) {
1987                         return (int)$s;
1988                 } else {
1989                         # This will also quote numeric values. This should be harmless,
1990                         # and protects against weird problems that occur when they really
1991                         # _are_ strings such as article titles and string->number->string
1992                         # conversion is not 1:1.
1993                         return "'" . $this->strencode( $s ) . "'";
1994                 }
1995         }
1996
1997         /**
1998          * Quotes an identifier using `backticks` or "double quotes" depending on the database type.
1999          * MySQL uses `backticks` while basically everything else uses double quotes.
2000          * Since MySQL is the odd one out here the double quotes are our generic
2001          * and we implement backticks in DatabaseMysql.
2002          *
2003          * @param string $s
2004          * @return string
2005          */
2006         public function addIdentifierQuotes( $s ) {
2007                 return '"' . str_replace( '"', '""', $s ) . '"';
2008         }
2009
2010         /**
2011          * Returns if the given identifier looks quoted or not according to
2012          * the database convention for quoting identifiers .
2013          *
2014          * @note Do not use this to determine if untrusted input is safe.
2015          *   A malicious user can trick this function.
2016          * @param string $name
2017          * @return bool
2018          */
2019         public function isQuotedIdentifier( $name ) {
2020                 return $name[0] == '"' && substr( $name, -1, 1 ) == '"';
2021         }
2022
2023         /**
2024          * @param string $s
2025          * @return string
2026          */
2027         protected function escapeLikeInternal( $s ) {
2028                 return addcslashes( $s, '\%_' );
2029         }
2030
2031         public function buildLike() {
2032                 $params = func_get_args();
2033
2034                 if ( count( $params ) > 0 && is_array( $params[0] ) ) {
2035                         $params = $params[0];
2036                 }
2037
2038                 $s = '';
2039
2040                 foreach ( $params as $value ) {
2041                         if ( $value instanceof LikeMatch ) {
2042                                 $s .= $value->toString();
2043                         } else {
2044                                 $s .= $this->escapeLikeInternal( $value );
2045                         }
2046                 }
2047
2048                 return " LIKE {$this->addQuotes( $s )} ";
2049         }
2050
2051         public function anyChar() {
2052                 return new LikeMatch( '_' );
2053         }
2054
2055         public function anyString() {
2056                 return new LikeMatch( '%' );
2057         }
2058
2059         public function nextSequenceValue( $seqName ) {
2060                 return null;
2061         }
2062
2063         /**
2064          * USE INDEX clause. Unlikely to be useful for anything but MySQL. This
2065          * is only needed because a) MySQL must be as efficient as possible due to
2066          * its use on Wikipedia, and b) MySQL 4.0 is kind of dumb sometimes about
2067          * which index to pick. Anyway, other databases might have different
2068          * indexes on a given table. So don't bother overriding this unless you're
2069          * MySQL.
2070          * @param string $index
2071          * @return string
2072          */
2073         public function useIndexClause( $index ) {
2074                 return '';
2075         }
2076
2077         /**
2078          * IGNORE INDEX clause. Unlikely to be useful for anything but MySQL. This
2079          * is only needed because a) MySQL must be as efficient as possible due to
2080          * its use on Wikipedia, and b) MySQL 4.0 is kind of dumb sometimes about
2081          * which index to pick. Anyway, other databases might have different
2082          * indexes on a given table. So don't bother overriding this unless you're
2083          * MySQL.
2084          * @param string $index
2085          * @return string
2086          */
2087         public function ignoreIndexClause( $index ) {
2088                 return '';
2089         }
2090
2091         public function replace( $table, $uniqueIndexes, $rows, $fname = __METHOD__ ) {
2092                 $quotedTable = $this->tableName( $table );
2093
2094                 if ( count( $rows ) == 0 ) {
2095                         return;
2096                 }
2097
2098                 # Single row case
2099                 if ( !is_array( reset( $rows ) ) ) {
2100                         $rows = [ $rows ];
2101                 }
2102
2103                 // @FXIME: this is not atomic, but a trx would break affectedRows()
2104                 foreach ( $rows as $row ) {
2105                         # Delete rows which collide
2106                         if ( $uniqueIndexes ) {
2107                                 $sql = "DELETE FROM $quotedTable WHERE ";
2108                                 $first = true;
2109                                 foreach ( $uniqueIndexes as $index ) {
2110                                         if ( $first ) {
2111                                                 $first = false;
2112                                                 $sql .= '( ';
2113                                         } else {
2114                                                 $sql .= ' ) OR ( ';
2115                                         }
2116                                         if ( is_array( $index ) ) {
2117                                                 $first2 = true;
2118                                                 foreach ( $index as $col ) {
2119                                                         if ( $first2 ) {
2120                                                                 $first2 = false;
2121                                                         } else {
2122                                                                 $sql .= ' AND ';
2123                                                         }
2124                                                         $sql .= $col . '=' . $this->addQuotes( $row[$col] );
2125                                                 }
2126                                         } else {
2127                                                 $sql .= $index . '=' . $this->addQuotes( $row[$index] );
2128                                         }
2129                                 }
2130                                 $sql .= ' )';
2131                                 $this->query( $sql, $fname );
2132                         }
2133
2134                         # Now insert the row
2135                         $this->insert( $table, $row, $fname );
2136                 }
2137         }
2138
2139         /**
2140          * REPLACE query wrapper for MySQL and SQLite, which have a native REPLACE
2141          * statement.
2142          *
2143          * @param string $table Table name
2144          * @param array|string $rows Row(s) to insert
2145          * @param string $fname Caller function name
2146          *
2147          * @return ResultWrapper
2148          */
2149         protected function nativeReplace( $table, $rows, $fname ) {
2150                 $table = $this->tableName( $table );
2151
2152                 # Single row case
2153                 if ( !is_array( reset( $rows ) ) ) {
2154                         $rows = [ $rows ];
2155                 }
2156
2157                 $sql = "REPLACE INTO $table (" . implode( ',', array_keys( $rows[0] ) ) . ') VALUES ';
2158                 $first = true;
2159
2160                 foreach ( $rows as $row ) {
2161                         if ( $first ) {
2162                                 $first = false;
2163                         } else {
2164                                 $sql .= ',';
2165                         }
2166
2167                         $sql .= '(' . $this->makeList( $row ) . ')';
2168                 }
2169
2170                 return $this->query( $sql, $fname );
2171         }
2172
2173         public function upsert( $table, array $rows, array $uniqueIndexes, array $set,
2174                 $fname = __METHOD__
2175         ) {
2176                 if ( !count( $rows ) ) {
2177                         return true; // nothing to do
2178                 }
2179
2180                 if ( !is_array( reset( $rows ) ) ) {
2181                         $rows = [ $rows ];
2182                 }
2183
2184                 if ( count( $uniqueIndexes ) ) {
2185                         $clauses = []; // list WHERE clauses that each identify a single row
2186                         foreach ( $rows as $row ) {
2187                                 foreach ( $uniqueIndexes as $index ) {
2188                                         $index = is_array( $index ) ? $index : [ $index ]; // columns
2189                                         $rowKey = []; // unique key to this row
2190                                         foreach ( $index as $column ) {
2191                                                 $rowKey[$column] = $row[$column];
2192                                         }
2193                                         $clauses[] = $this->makeList( $rowKey, self::LIST_AND );
2194                                 }
2195                         }
2196                         $where = [ $this->makeList( $clauses, self::LIST_OR ) ];
2197                 } else {
2198                         $where = false;
2199                 }
2200
2201                 $useTrx = !$this->mTrxLevel;
2202                 if ( $useTrx ) {
2203                         $this->begin( $fname, self::TRANSACTION_INTERNAL );
2204                 }
2205                 try {
2206                         # Update any existing conflicting row(s)
2207                         if ( $where !== false ) {
2208                                 $ok = $this->update( $table, $set, $where, $fname );
2209                         } else {
2210                                 $ok = true;
2211                         }
2212                         # Now insert any non-conflicting row(s)
2213                         $ok = $this->insert( $table, $rows, $fname, [ 'IGNORE' ] ) && $ok;
2214                 } catch ( Exception $e ) {
2215                         if ( $useTrx ) {
2216                                 $this->rollback( $fname, self::FLUSHING_INTERNAL );
2217                         }
2218                         throw $e;
2219                 }
2220                 if ( $useTrx ) {
2221                         $this->commit( $fname, self::FLUSHING_INTERNAL );
2222                 }
2223
2224                 return $ok;
2225         }
2226
2227         public function deleteJoin( $delTable, $joinTable, $delVar, $joinVar, $conds,
2228                 $fname = __METHOD__
2229         ) {
2230                 if ( !$conds ) {
2231                         throw new DBUnexpectedError( $this, __METHOD__ . ' called with empty $conds' );
2232                 }
2233
2234                 $delTable = $this->tableName( $delTable );
2235                 $joinTable = $this->tableName( $joinTable );
2236                 $sql = "DELETE FROM $delTable WHERE $delVar IN (SELECT $joinVar FROM $joinTable ";
2237                 if ( $conds != '*' ) {
2238                         $sql .= 'WHERE ' . $this->makeList( $conds, self::LIST_AND );
2239                 }
2240                 $sql .= ')';
2241
2242                 $this->query( $sql, $fname );
2243         }
2244
2245         /**
2246          * Returns the size of a text field, or -1 for "unlimited"
2247          *
2248          * @param string $table
2249          * @param string $field
2250          * @return int
2251          */
2252         public function textFieldSize( $table, $field ) {
2253                 $table = $this->tableName( $table );
2254                 $sql = "SHOW COLUMNS FROM $table LIKE \"$field\";";
2255                 $res = $this->query( $sql, __METHOD__ );
2256                 $row = $this->fetchObject( $res );
2257
2258                 $m = [];
2259
2260                 if ( preg_match( '/\((.*)\)/', $row->Type, $m ) ) {
2261                         $size = $m[1];
2262                 } else {
2263                         $size = -1;
2264                 }
2265
2266                 return $size;
2267         }
2268
2269         public function delete( $table, $conds, $fname = __METHOD__ ) {
2270                 if ( !$conds ) {
2271                         throw new DBUnexpectedError( $this, __METHOD__ . ' called with no conditions' );
2272                 }
2273
2274                 $table = $this->tableName( $table );
2275                 $sql = "DELETE FROM $table";
2276
2277                 if ( $conds != '*' ) {
2278                         if ( is_array( $conds ) ) {
2279                                 $conds = $this->makeList( $conds, self::LIST_AND );
2280                         }
2281                         $sql .= ' WHERE ' . $conds;
2282                 }
2283
2284                 return $this->query( $sql, $fname );
2285         }
2286
2287         public function insertSelect(
2288                 $destTable, $srcTable, $varMap, $conds,
2289                 $fname = __METHOD__, $insertOptions = [], $selectOptions = []
2290         ) {
2291                 if ( $this->cliMode ) {
2292                         // For massive migrations with downtime, we don't want to select everything
2293                         // into memory and OOM, so do all this native on the server side if possible.
2294                         return $this->nativeInsertSelect(
2295                                 $destTable,
2296                                 $srcTable,
2297                                 $varMap,
2298                                 $conds,
2299                                 $fname,
2300                                 $insertOptions,
2301                                 $selectOptions
2302                         );
2303                 }
2304
2305                 // For web requests, do a locking SELECT and then INSERT. This puts the SELECT burden
2306                 // on only the master (without needing row-based-replication). It also makes it easy to
2307                 // know how big the INSERT is going to be.
2308                 $fields = [];
2309                 foreach ( $varMap as $dstColumn => $sourceColumnOrSql ) {
2310                         $fields[] = $this->fieldNameWithAlias( $sourceColumnOrSql, $dstColumn );
2311                 }
2312                 $selectOptions[] = 'FOR UPDATE';
2313                 $res = $this->select( $srcTable, implode( ',', $fields ), $conds, $fname, $selectOptions );
2314                 if ( !$res ) {
2315                         return false;
2316                 }
2317
2318                 $rows = [];
2319                 foreach ( $res as $row ) {
2320                         $rows[] = (array)$row;
2321                 }
2322
2323                 return $this->insert( $destTable, $rows, $fname, $insertOptions );
2324         }
2325
2326         protected function nativeInsertSelect( $destTable, $srcTable, $varMap, $conds,
2327                 $fname = __METHOD__,
2328                 $insertOptions = [], $selectOptions = []
2329         ) {
2330                 $destTable = $this->tableName( $destTable );
2331
2332                 if ( !is_array( $insertOptions ) ) {
2333                         $insertOptions = [ $insertOptions ];
2334                 }
2335
2336                 $insertOptions = $this->makeInsertOptions( $insertOptions );
2337
2338                 if ( !is_array( $selectOptions ) ) {
2339                         $selectOptions = [ $selectOptions ];
2340                 }
2341
2342                 list( $startOpts, $useIndex, $tailOpts, $ignoreIndex ) = $this->makeSelectOptions(
2343                         $selectOptions );
2344
2345                 if ( is_array( $srcTable ) ) {
2346                         $srcTable = implode( ',', array_map( [ &$this, 'tableName' ], $srcTable ) );
2347                 } else {
2348                         $srcTable = $this->tableName( $srcTable );
2349                 }
2350
2351                 $sql = "INSERT $insertOptions INTO $destTable (" . implode( ',', array_keys( $varMap ) ) . ')' .
2352                         " SELECT $startOpts " . implode( ',', $varMap ) .
2353                         " FROM $srcTable $useIndex $ignoreIndex ";
2354
2355                 if ( $conds != '*' ) {
2356                         if ( is_array( $conds ) ) {
2357                                 $conds = $this->makeList( $conds, self::LIST_AND );
2358                         }
2359                         $sql .= " WHERE $conds";
2360                 }
2361
2362                 $sql .= " $tailOpts";
2363
2364                 return $this->query( $sql, $fname );
2365         }
2366
2367         /**
2368          * Construct a LIMIT query with optional offset. This is used for query
2369          * pages. The SQL should be adjusted so that only the first $limit rows
2370          * are returned. If $offset is provided as well, then the first $offset
2371          * rows should be discarded, and the next $limit rows should be returned.
2372          * If the result of the query is not ordered, then the rows to be returned
2373          * are theoretically arbitrary.
2374          *
2375          * $sql is expected to be a SELECT, if that makes a difference.
2376          *
2377          * The version provided by default works in MySQL and SQLite. It will very
2378          * likely need to be overridden for most other DBMSes.
2379          *
2380          * @param string $sql SQL query we will append the limit too
2381          * @param int $limit The SQL limit
2382          * @param int|bool $offset The SQL offset (default false)
2383          * @throws DBUnexpectedError
2384          * @return string
2385          */
2386         public function limitResult( $sql, $limit, $offset = false ) {
2387                 if ( !is_numeric( $limit ) ) {
2388                         throw new DBUnexpectedError( $this,
2389                                 "Invalid non-numeric limit passed to limitResult()\n" );
2390                 }
2391
2392                 return "$sql LIMIT "
2393                 . ( ( is_numeric( $offset ) && $offset != 0 ) ? "{$offset}," : "" )
2394                 . "{$limit} ";
2395         }
2396
2397         public function unionSupportsOrderAndLimit() {
2398                 return true; // True for almost every DB supported
2399         }
2400
2401         public function unionQueries( $sqls, $all ) {
2402                 $glue = $all ? ') UNION ALL (' : ') UNION (';
2403
2404                 return '(' . implode( $glue, $sqls ) . ')';
2405         }
2406
2407         public function conditional( $cond, $trueVal, $falseVal ) {
2408                 if ( is_array( $cond ) ) {
2409                         $cond = $this->makeList( $cond, self::LIST_AND );
2410                 }
2411
2412                 return " (CASE WHEN $cond THEN $trueVal ELSE $falseVal END) ";
2413         }
2414
2415         public function strreplace( $orig, $old, $new ) {
2416                 return "REPLACE({$orig}, {$old}, {$new})";
2417         }
2418
2419         public function getServerUptime() {
2420                 return 0;
2421         }
2422
2423         public function wasDeadlock() {
2424                 return false;
2425         }
2426
2427         public function wasLockTimeout() {
2428                 return false;
2429         }
2430
2431         public function wasErrorReissuable() {
2432                 return false;
2433         }
2434
2435         public function wasReadOnlyError() {
2436                 return false;
2437         }
2438
2439         /**
2440          * Do no use the class outside of Database/DBError classes
2441          *
2442          * @param integer|string $errno
2443          * @return bool Whether the given query error was a connection drop
2444          */
2445         public function wasConnectionError( $errno ) {
2446                 return false;
2447         }
2448
2449         /**
2450          * Perform a deadlock-prone transaction.
2451          *
2452          * This function invokes a callback function to perform a set of write
2453          * queries. If a deadlock occurs during the processing, the transaction
2454          * will be rolled back and the callback function will be called again.
2455          *
2456          * Avoid using this method outside of Job or Maintenance classes.
2457          *
2458          * Usage:
2459          *   $dbw->deadlockLoop( callback, ... );
2460          *
2461          * Extra arguments are passed through to the specified callback function.
2462          * This method requires that no transactions are already active to avoid
2463          * causing premature commits or exceptions.
2464          *
2465          * Returns whatever the callback function returned on its successful,
2466          * iteration, or false on error, for example if the retry limit was
2467          * reached.
2468          *
2469          * @return mixed
2470          * @throws DBUnexpectedError
2471          * @throws Exception
2472          */
2473         public function deadlockLoop() {
2474                 $args = func_get_args();
2475                 $function = array_shift( $args );
2476                 $tries = self::DEADLOCK_TRIES;
2477
2478                 $this->begin( __METHOD__ );
2479
2480                 $retVal = null;
2481                 /** @var Exception $e */
2482                 $e = null;
2483                 do {
2484                         try {
2485                                 $retVal = call_user_func_array( $function, $args );
2486                                 break;
2487                         } catch ( DBQueryError $e ) {
2488                                 if ( $this->wasDeadlock() ) {
2489                                         // Retry after a randomized delay
2490                                         usleep( mt_rand( self::DEADLOCK_DELAY_MIN, self::DEADLOCK_DELAY_MAX ) );
2491                                 } else {
2492                                         // Throw the error back up
2493                                         throw $e;
2494                                 }
2495                         }
2496                 } while ( --$tries > 0 );
2497
2498                 if ( $tries <= 0 ) {
2499                         // Too many deadlocks; give up
2500                         $this->rollback( __METHOD__ );
2501                         throw $e;
2502                 } else {
2503                         $this->commit( __METHOD__ );
2504
2505                         return $retVal;
2506                 }
2507         }
2508
2509         public function masterPosWait( DBMasterPos $pos, $timeout ) {
2510                 # Real waits are implemented in the subclass.
2511                 return 0;
2512         }
2513
2514         public function getSlavePos() {
2515                 # Stub
2516                 return false;
2517         }
2518
2519         public function getMasterPos() {
2520                 # Stub
2521                 return false;
2522         }
2523
2524         public function serverIsReadOnly() {
2525                 return false;
2526         }
2527
2528         final public function onTransactionResolution( callable $callback, $fname = __METHOD__ ) {
2529                 if ( !$this->mTrxLevel ) {
2530                         throw new DBUnexpectedError( $this, "No transaction is active." );
2531                 }
2532                 $this->mTrxEndCallbacks[] = [ $callback, $fname ];
2533         }
2534
2535         final public function onTransactionIdle( callable $callback, $fname = __METHOD__ ) {
2536                 $this->mTrxIdleCallbacks[] = [ $callback, $fname ];
2537                 if ( !$this->mTrxLevel ) {
2538                         $this->runOnTransactionIdleCallbacks( self::TRIGGER_IDLE );
2539                 }
2540         }
2541
2542         final public function onTransactionPreCommitOrIdle( callable $callback, $fname = __METHOD__ ) {
2543                 if ( $this->mTrxLevel ) {
2544                         $this->mTrxPreCommitCallbacks[] = [ $callback, $fname ];
2545                 } else {
2546                         // If no transaction is active, then make one for this callback
2547                         $this->startAtomic( __METHOD__ );
2548                         try {
2549                                 call_user_func( $callback );
2550                                 $this->endAtomic( __METHOD__ );
2551                         } catch ( Exception $e ) {
2552                                 $this->rollback( __METHOD__, self::FLUSHING_INTERNAL );
2553                                 throw $e;
2554                         }
2555                 }
2556         }
2557
2558         final public function setTransactionListener( $name, callable $callback = null ) {
2559                 if ( $callback ) {
2560                         $this->mTrxRecurringCallbacks[$name] = $callback;
2561                 } else {
2562                         unset( $this->mTrxRecurringCallbacks[$name] );
2563                 }
2564         }
2565
2566         /**
2567          * Whether to disable running of post-COMMIT/ROLLBACK callbacks
2568          *
2569          * This method should not be used outside of Database/LoadBalancer
2570          *
2571          * @param bool $suppress
2572          * @since 1.28
2573          */
2574         final public function setTrxEndCallbackSuppression( $suppress ) {
2575                 $this->mTrxEndCallbacksSuppressed = $suppress;
2576         }
2577
2578         /**
2579          * Actually run and consume any "on transaction idle/resolution" callbacks.
2580          *
2581          * This method should not be used outside of Database/LoadBalancer
2582          *
2583          * @param integer $trigger IDatabase::TRIGGER_* constant
2584          * @since 1.20
2585          * @throws Exception
2586          */
2587         public function runOnTransactionIdleCallbacks( $trigger ) {
2588                 if ( $this->mTrxEndCallbacksSuppressed ) {
2589                         return;
2590                 }
2591
2592                 $autoTrx = $this->getFlag( DBO_TRX ); // automatic begin() enabled?
2593                 /** @var Exception $e */
2594                 $e = null; // first exception
2595                 do { // callbacks may add callbacks :)
2596                         $callbacks = array_merge(
2597                                 $this->mTrxIdleCallbacks,
2598                                 $this->mTrxEndCallbacks // include "transaction resolution" callbacks
2599                         );
2600                         $this->mTrxIdleCallbacks = []; // consumed (and recursion guard)
2601                         $this->mTrxEndCallbacks = []; // consumed (recursion guard)
2602                         foreach ( $callbacks as $callback ) {
2603                                 try {
2604                                         list( $phpCallback ) = $callback;
2605                                         $this->clearFlag( DBO_TRX ); // make each query its own transaction
2606                                         call_user_func_array( $phpCallback, [ $trigger ] );
2607                                         if ( $autoTrx ) {
2608                                                 $this->setFlag( DBO_TRX ); // restore automatic begin()
2609                                         } else {
2610                                                 $this->clearFlag( DBO_TRX ); // restore auto-commit
2611                                         }
2612                                 } catch ( Exception $ex ) {
2613                                         call_user_func( $this->errorLogger, $ex );
2614                                         $e = $e ?: $ex;
2615                                         // Some callbacks may use startAtomic/endAtomic, so make sure
2616                                         // their transactions are ended so other callbacks don't fail
2617                                         if ( $this->trxLevel() ) {
2618                                                 $this->rollback( __METHOD__, self::FLUSHING_INTERNAL );
2619                                         }
2620                                 }
2621                         }
2622                 } while ( count( $this->mTrxIdleCallbacks ) );
2623
2624                 if ( $e instanceof Exception ) {
2625                         throw $e; // re-throw any first exception
2626                 }
2627         }
2628
2629         /**
2630          * Actually run and consume any "on transaction pre-commit" callbacks.
2631          *
2632          * This method should not be used outside of Database/LoadBalancer
2633          *
2634          * @since 1.22
2635          * @throws Exception
2636          */
2637         public function runOnTransactionPreCommitCallbacks() {
2638                 $e = null; // first exception
2639                 do { // callbacks may add callbacks :)
2640                         $callbacks = $this->mTrxPreCommitCallbacks;
2641                         $this->mTrxPreCommitCallbacks = []; // consumed (and recursion guard)
2642                         foreach ( $callbacks as $callback ) {
2643                                 try {
2644                                         list( $phpCallback ) = $callback;
2645                                         call_user_func( $phpCallback );
2646                                 } catch ( Exception $ex ) {
2647                                         call_user_func( $this->errorLogger, $ex );
2648                                         $e = $e ?: $ex;
2649                                 }
2650                         }
2651                 } while ( count( $this->mTrxPreCommitCallbacks ) );
2652
2653                 if ( $e instanceof Exception ) {
2654                         throw $e; // re-throw any first exception
2655                 }
2656         }
2657
2658         /**
2659          * Actually run any "transaction listener" callbacks.
2660          *
2661          * This method should not be used outside of Database/LoadBalancer
2662          *
2663          * @param integer $trigger IDatabase::TRIGGER_* constant
2664          * @throws Exception
2665          * @since 1.20
2666          */
2667         public function runTransactionListenerCallbacks( $trigger ) {
2668                 if ( $this->mTrxEndCallbacksSuppressed ) {
2669                         return;
2670                 }
2671
2672                 /** @var Exception $e */
2673                 $e = null; // first exception
2674
2675                 foreach ( $this->mTrxRecurringCallbacks as $phpCallback ) {
2676                         try {
2677                                 $phpCallback( $trigger, $this );
2678                         } catch ( Exception $ex ) {
2679                                 call_user_func( $this->errorLogger, $ex );
2680                                 $e = $e ?: $ex;
2681                         }
2682                 }
2683
2684                 if ( $e instanceof Exception ) {
2685                         throw $e; // re-throw any first exception
2686                 }
2687         }
2688
2689         final public function startAtomic( $fname = __METHOD__ ) {
2690                 if ( !$this->mTrxLevel ) {
2691                         $this->begin( $fname, self::TRANSACTION_INTERNAL );
2692                         // If DBO_TRX is set, a series of startAtomic/endAtomic pairs will result
2693                         // in all changes being in one transaction to keep requests transactional.
2694                         if ( !$this->getFlag( DBO_TRX ) ) {
2695                                 $this->mTrxAutomaticAtomic = true;
2696                         }
2697                 }
2698
2699                 $this->mTrxAtomicLevels[] = $fname;
2700         }
2701
2702         final public function endAtomic( $fname = __METHOD__ ) {
2703                 if ( !$this->mTrxLevel ) {
2704                         throw new DBUnexpectedError( $this, "No atomic transaction is open (got $fname)." );
2705                 }
2706                 if ( !$this->mTrxAtomicLevels ||
2707                         array_pop( $this->mTrxAtomicLevels ) !== $fname
2708                 ) {
2709                         throw new DBUnexpectedError( $this, "Invalid atomic section ended (got $fname)." );
2710                 }
2711
2712                 if ( !$this->mTrxAtomicLevels && $this->mTrxAutomaticAtomic ) {
2713                         $this->commit( $fname, self::FLUSHING_INTERNAL );
2714                 }
2715         }
2716
2717         final public function doAtomicSection( $fname, callable $callback ) {
2718                 $this->startAtomic( $fname );
2719                 try {
2720                         $res = call_user_func_array( $callback, [ $this, $fname ] );
2721                 } catch ( Exception $e ) {
2722                         $this->rollback( $fname, self::FLUSHING_INTERNAL );
2723                         throw $e;
2724                 }
2725                 $this->endAtomic( $fname );
2726
2727                 return $res;
2728         }
2729
2730         final public function begin( $fname = __METHOD__, $mode = self::TRANSACTION_EXPLICIT ) {
2731                 // Protect against mismatched atomic section, transaction nesting, and snapshot loss
2732                 if ( $this->mTrxLevel ) {
2733                         if ( $this->mTrxAtomicLevels ) {
2734                                 $levels = implode( ', ', $this->mTrxAtomicLevels );
2735                                 $msg = "$fname: Got explicit BEGIN while atomic section(s) $levels are open.";
2736                                 throw new DBUnexpectedError( $this, $msg );
2737                         } elseif ( !$this->mTrxAutomatic ) {
2738                                 $msg = "$fname: Explicit transaction already active (from {$this->mTrxFname}).";
2739                                 throw new DBUnexpectedError( $this, $msg );
2740                         } else {
2741                                 // @TODO: make this an exception at some point
2742                                 $msg = "$fname: Implicit transaction already active (from {$this->mTrxFname}).";
2743                                 $this->queryLogger->error( $msg );
2744                                 return; // join the main transaction set
2745                         }
2746                 } elseif ( $this->getFlag( DBO_TRX ) && $mode !== self::TRANSACTION_INTERNAL ) {
2747                         // @TODO: make this an exception at some point
2748                         $msg = "$fname: Implicit transaction expected (DBO_TRX set).";
2749                         $this->queryLogger->error( $msg );
2750                         return; // let any writes be in the main transaction
2751                 }
2752
2753                 // Avoid fatals if close() was called
2754                 $this->assertOpen();
2755
2756                 $this->doBegin( $fname );
2757                 $this->mTrxTimestamp = microtime( true );
2758                 $this->mTrxFname = $fname;
2759                 $this->mTrxDoneWrites = false;
2760                 $this->mTrxAutomatic = ( $mode === self::TRANSACTION_INTERNAL );
2761                 $this->mTrxAutomaticAtomic = false;
2762                 $this->mTrxAtomicLevels = [];
2763                 $this->mTrxShortId = sprintf( '%06x', mt_rand( 0, 0xffffff ) );
2764                 $this->mTrxWriteDuration = 0.0;
2765                 $this->mTrxWriteQueryCount = 0;
2766                 $this->mTrxWriteAdjDuration = 0.0;
2767                 $this->mTrxWriteAdjQueryCount = 0;
2768                 $this->mTrxWriteCallers = [];
2769                 // First SELECT after BEGIN will establish the snapshot in REPEATABLE-READ.
2770                 // Get an estimate of the replica DB lag before then, treating estimate staleness
2771                 // as lag itself just to be safe
2772                 $status = $this->getApproximateLagStatus();
2773                 $this->mTrxReplicaLag = $status['lag'] + ( microtime( true ) - $status['since'] );
2774         }
2775
2776         /**
2777          * Issues the BEGIN command to the database server.
2778          *
2779          * @see DatabaseBase::begin()
2780          * @param string $fname
2781          */
2782         protected function doBegin( $fname ) {
2783                 $this->query( 'BEGIN', $fname );
2784                 $this->mTrxLevel = 1;
2785         }
2786
2787         final public function commit( $fname = __METHOD__, $flush = '' ) {
2788                 if ( $this->mTrxLevel && $this->mTrxAtomicLevels ) {
2789                         // There are still atomic sections open. This cannot be ignored
2790                         $levels = implode( ', ', $this->mTrxAtomicLevels );
2791                         throw new DBUnexpectedError(
2792                                 $this,
2793                                 "$fname: Got COMMIT while atomic sections $levels are still open."
2794                         );
2795                 }
2796
2797                 if ( $flush === self::FLUSHING_INTERNAL || $flush === self::FLUSHING_ALL_PEERS ) {
2798                         if ( !$this->mTrxLevel ) {
2799                                 return; // nothing to do
2800                         } elseif ( !$this->mTrxAutomatic ) {
2801                                 throw new DBUnexpectedError(
2802                                         $this,
2803                                         "$fname: Flushing an explicit transaction, getting out of sync."
2804                                 );
2805                         }
2806                 } else {
2807                         if ( !$this->mTrxLevel ) {
2808                                 $this->queryLogger->error( "$fname: No transaction to commit, something got out of sync." );
2809                                 return; // nothing to do
2810                         } elseif ( $this->mTrxAutomatic ) {
2811                                 // @TODO: make this an exception at some point
2812                                 $msg = "$fname: Explicit commit of implicit transaction.";
2813                                 $this->queryLogger->error( $msg );
2814                                 return; // wait for the main transaction set commit round
2815                         }
2816                 }
2817
2818                 // Avoid fatals if close() was called
2819                 $this->assertOpen();
2820
2821                 $this->runOnTransactionPreCommitCallbacks();
2822                 $writeTime = $this->pendingWriteQueryDuration( self::ESTIMATE_DB_APPLY );
2823                 $this->doCommit( $fname );
2824                 if ( $this->mTrxDoneWrites ) {
2825                         $this->mDoneWrites = microtime( true );
2826                         $this->trxProfiler->transactionWritingOut(
2827                                 $this->mServer, $this->mDBname, $this->mTrxShortId, $writeTime );
2828                 }
2829
2830                 $this->runOnTransactionIdleCallbacks( self::TRIGGER_COMMIT );
2831                 $this->runTransactionListenerCallbacks( self::TRIGGER_COMMIT );
2832         }
2833
2834         /**
2835          * Issues the COMMIT command to the database server.
2836          *
2837          * @see DatabaseBase::commit()
2838          * @param string $fname
2839          */
2840         protected function doCommit( $fname ) {
2841                 if ( $this->mTrxLevel ) {
2842                         $this->query( 'COMMIT', $fname );
2843                         $this->mTrxLevel = 0;
2844                 }
2845         }
2846
2847         final public function rollback( $fname = __METHOD__, $flush = '' ) {
2848                 if ( $flush === self::FLUSHING_INTERNAL || $flush === self::FLUSHING_ALL_PEERS ) {
2849                         if ( !$this->mTrxLevel ) {
2850                                 return; // nothing to do
2851                         }
2852                 } else {
2853                         if ( !$this->mTrxLevel ) {
2854                                 $this->queryLogger->error(
2855                                         "$fname: No transaction to rollback, something got out of sync." );
2856                                 return; // nothing to do
2857                         } elseif ( $this->getFlag( DBO_TRX ) ) {
2858                                 throw new DBUnexpectedError(
2859                                         $this,
2860                                         "$fname: Expected mass rollback of all peer databases (DBO_TRX set)."
2861                                 );
2862                         }
2863                 }
2864
2865                 // Avoid fatals if close() was called
2866                 $this->assertOpen();
2867
2868                 $this->doRollback( $fname );
2869                 $this->mTrxAtomicLevels = [];
2870                 if ( $this->mTrxDoneWrites ) {
2871                         $this->trxProfiler->transactionWritingOut(
2872                                 $this->mServer, $this->mDBname, $this->mTrxShortId );
2873                 }
2874
2875                 $this->mTrxIdleCallbacks = []; // clear
2876                 $this->mTrxPreCommitCallbacks = []; // clear
2877                 $this->runOnTransactionIdleCallbacks( self::TRIGGER_ROLLBACK );
2878                 $this->runTransactionListenerCallbacks( self::TRIGGER_ROLLBACK );
2879         }
2880
2881         /**
2882          * Issues the ROLLBACK command to the database server.
2883          *
2884          * @see DatabaseBase::rollback()
2885          * @param string $fname
2886          */
2887         protected function doRollback( $fname ) {
2888                 if ( $this->mTrxLevel ) {
2889                         # Disconnects cause rollback anyway, so ignore those errors
2890                         $ignoreErrors = true;
2891                         $this->query( 'ROLLBACK', $fname, $ignoreErrors );
2892                         $this->mTrxLevel = 0;
2893                 }
2894         }
2895
2896         public function flushSnapshot( $fname = __METHOD__ ) {
2897                 if ( $this->writesOrCallbacksPending() || $this->explicitTrxActive() ) {
2898                         // This only flushes transactions to clear snapshots, not to write data
2899                         $fnames = implode( ', ', $this->pendingWriteAndCallbackCallers() );
2900                         throw new DBUnexpectedError(
2901                                 $this,
2902                                 "$fname: Cannot COMMIT to clear snapshot because writes are pending ($fnames)."
2903                         );
2904                 }
2905
2906                 $this->commit( $fname, self::FLUSHING_INTERNAL );
2907         }
2908
2909         public function explicitTrxActive() {
2910                 return $this->mTrxLevel && ( $this->mTrxAtomicLevels || !$this->mTrxAutomatic );
2911         }
2912
2913         /**
2914          * Creates a new table with structure copied from existing table
2915          * Note that unlike most database abstraction functions, this function does not
2916          * automatically append database prefix, because it works at a lower
2917          * abstraction level.
2918          * The table names passed to this function shall not be quoted (this
2919          * function calls addIdentifierQuotes when needed).
2920          *
2921          * @param string $oldName Name of table whose structure should be copied
2922          * @param string $newName Name of table to be created
2923          * @param bool $temporary Whether the new table should be temporary
2924          * @param string $fname Calling function name
2925          * @throws RuntimeException
2926          * @return bool True if operation was successful
2927          */
2928         public function duplicateTableStructure( $oldName, $newName, $temporary = false,
2929                 $fname = __METHOD__
2930         ) {
2931                 throw new RuntimeException( __METHOD__ . ' is not implemented in descendant class' );
2932         }
2933
2934         public function listTables( $prefix = null, $fname = __METHOD__ ) {
2935                 throw new RuntimeException( __METHOD__ . ' is not implemented in descendant class' );
2936         }
2937
2938         /**
2939          * Reset the views process cache set by listViews()
2940          * @since 1.22
2941          */
2942         final public function clearViewsCache() {
2943                 $this->allViews = null;
2944         }
2945
2946         /**
2947          * Lists all the VIEWs in the database
2948          *
2949          * For caching purposes the list of all views should be stored in
2950          * $this->allViews. The process cache can be cleared with clearViewsCache()
2951          *
2952          * @param string $prefix Only show VIEWs with this prefix, eg. unit_test_
2953          * @param string $fname Name of calling function
2954          * @throws RuntimeException
2955          * @return array
2956          * @since 1.22
2957          */
2958         public function listViews( $prefix = null, $fname = __METHOD__ ) {
2959                 throw new RuntimeException( __METHOD__ . ' is not implemented in descendant class' );
2960         }
2961
2962         /**
2963          * Differentiates between a TABLE and a VIEW
2964          *
2965          * @param string $name Name of the database-structure to test.
2966          * @throws RuntimeException
2967          * @return bool
2968          * @since 1.22
2969          */
2970         public function isView( $name ) {
2971                 throw new RuntimeException( __METHOD__ . ' is not implemented in descendant class' );
2972         }
2973
2974         public function timestamp( $ts = 0 ) {
2975                 $t = new ConvertableTimestamp( $ts );
2976                 // Let errors bubble up to avoid putting garbage in the DB
2977                 return $t->getTimestamp( TS_MW );
2978         }
2979
2980         public function timestampOrNull( $ts = null ) {
2981                 if ( is_null( $ts ) ) {
2982                         return null;
2983                 } else {
2984                         return $this->timestamp( $ts );
2985                 }
2986         }
2987
2988         /**
2989          * Take the result from a query, and wrap it in a ResultWrapper if
2990          * necessary. Boolean values are passed through as is, to indicate success
2991          * of write queries or failure.
2992          *
2993          * Once upon a time, DatabaseBase::query() returned a bare MySQL result
2994          * resource, and it was necessary to call this function to convert it to
2995          * a wrapper. Nowadays, raw database objects are never exposed to external
2996          * callers, so this is unnecessary in external code.
2997          *
2998          * @param bool|ResultWrapper|resource|object $result
2999          * @return bool|ResultWrapper
3000          */
3001         protected function resultObject( $result ) {
3002                 if ( !$result ) {
3003                         return false;
3004                 } elseif ( $result instanceof ResultWrapper ) {
3005                         return $result;
3006                 } elseif ( $result === true ) {
3007                         // Successful write query
3008                         return $result;
3009                 } else {
3010                         return new ResultWrapper( $this, $result );
3011                 }
3012         }
3013
3014         public function ping( &$rtt = null ) {
3015                 // Avoid hitting the server if it was hit recently
3016                 if ( $this->isOpen() && ( microtime( true ) - $this->lastPing ) < self::PING_TTL ) {
3017                         if ( !func_num_args() || $this->mRTTEstimate > 0 ) {
3018                                 $rtt = $this->mRTTEstimate;
3019                                 return true; // don't care about $rtt
3020                         }
3021                 }
3022
3023                 // This will reconnect if possible or return false if not
3024                 $this->clearFlag( DBO_TRX, self::REMEMBER_PRIOR );
3025                 $ok = ( $this->query( self::PING_QUERY, __METHOD__, true ) !== false );
3026                 $this->restoreFlags( self::RESTORE_PRIOR );
3027
3028                 if ( $ok ) {
3029                         $rtt = $this->mRTTEstimate;
3030                 }
3031
3032                 return $ok;
3033         }
3034
3035         /**
3036          * @return bool
3037          */
3038         protected function reconnect() {
3039                 $this->closeConnection();
3040                 $this->mOpened = false;
3041                 $this->mConn = false;
3042                 try {
3043                         $this->open( $this->mServer, $this->mUser, $this->mPassword, $this->mDBname );
3044                         $this->lastPing = microtime( true );
3045                         $ok = true;
3046                 } catch ( DBConnectionError $e ) {
3047                         $ok = false;
3048                 }
3049
3050                 return $ok;
3051         }
3052
3053         public function getSessionLagStatus() {
3054                 return $this->getTransactionLagStatus() ?: $this->getApproximateLagStatus();
3055         }
3056
3057         /**
3058          * Get the replica DB lag when the current transaction started
3059          *
3060          * This is useful when transactions might use snapshot isolation
3061          * (e.g. REPEATABLE-READ in innodb), so the "real" lag of that data
3062          * is this lag plus transaction duration. If they don't, it is still
3063          * safe to be pessimistic. This returns null if there is no transaction.
3064          *
3065          * @return array|null ('lag': seconds or false on error, 'since': UNIX timestamp of BEGIN)
3066          * @since 1.27
3067          */
3068         protected function getTransactionLagStatus() {
3069                 return $this->mTrxLevel
3070                         ? [ 'lag' => $this->mTrxReplicaLag, 'since' => $this->trxTimestamp() ]
3071                         : null;
3072         }
3073
3074         /**
3075          * Get a replica DB lag estimate for this server
3076          *
3077          * @return array ('lag': seconds or false on error, 'since': UNIX timestamp of estimate)
3078          * @since 1.27
3079          */
3080         protected function getApproximateLagStatus() {
3081                 return [
3082                         'lag'   => $this->getLBInfo( 'replica' ) ? $this->getLag() : 0,
3083                         'since' => microtime( true )
3084                 ];
3085         }
3086
3087         /**
3088          * Merge the result of getSessionLagStatus() for several DBs
3089          * using the most pessimistic values to estimate the lag of
3090          * any data derived from them in combination
3091          *
3092          * This is information is useful for caching modules
3093          *
3094          * @see WANObjectCache::set()
3095          * @see WANObjectCache::getWithSetCallback()
3096          *
3097          * @param IDatabase $db1
3098          * @param IDatabase ...
3099          * @return array Map of values:
3100          *   - lag: highest lag of any of the DBs or false on error (e.g. replication stopped)
3101          *   - since: oldest UNIX timestamp of any of the DB lag estimates
3102          *   - pending: whether any of the DBs have uncommitted changes
3103          * @since 1.27
3104          */
3105         public static function getCacheSetOptions( IDatabase $db1 ) {
3106                 $res = [ 'lag' => 0, 'since' => INF, 'pending' => false ];
3107                 foreach ( func_get_args() as $db ) {
3108                         /** @var IDatabase $db */
3109                         $status = $db->getSessionLagStatus();
3110                         if ( $status['lag'] === false ) {
3111                                 $res['lag'] = false;
3112                         } elseif ( $res['lag'] !== false ) {
3113                                 $res['lag'] = max( $res['lag'], $status['lag'] );
3114                         }
3115                         $res['since'] = min( $res['since'], $status['since'] );
3116                         $res['pending'] = $res['pending'] ?: $db->writesPending();
3117                 }
3118
3119                 return $res;
3120         }
3121
3122         public function getLag() {
3123                 return 0;
3124         }
3125
3126         public function maxListLen() {
3127                 return 0;
3128         }
3129
3130         public function encodeBlob( $b ) {
3131                 return $b;
3132         }
3133
3134         public function decodeBlob( $b ) {
3135                 if ( $b instanceof Blob ) {
3136                         $b = $b->fetch();
3137                 }
3138                 return $b;
3139         }
3140
3141         public function setSessionOptions( array $options ) {
3142         }
3143
3144         /**
3145          * Read and execute SQL commands from a file.
3146          *
3147          * Returns true on success, error string or exception on failure (depending
3148          * on object's error ignore settings).
3149          *
3150          * @param string $filename File name to open
3151          * @param bool|callable $lineCallback Optional function called before reading each line
3152          * @param bool|callable $resultCallback Optional function called for each MySQL result
3153          * @param bool|string $fname Calling function name or false if name should be
3154          *   generated dynamically using $filename
3155          * @param bool|callable $inputCallback Optional function called for each
3156          *   complete line sent
3157          * @return bool|string
3158          * @throws Exception
3159          */
3160         public function sourceFile(
3161                 $filename, $lineCallback = false, $resultCallback = false, $fname = false, $inputCallback = false
3162         ) {
3163                 MediaWiki\suppressWarnings();
3164                 $fp = fopen( $filename, 'r' );
3165                 MediaWiki\restoreWarnings();
3166
3167                 if ( false === $fp ) {
3168                         throw new RuntimeException( "Could not open \"{$filename}\".\n" );
3169                 }
3170
3171                 if ( !$fname ) {
3172                         $fname = __METHOD__ . "( $filename )";
3173                 }
3174
3175                 try {
3176                         $error = $this->sourceStream( $fp, $lineCallback, $resultCallback, $fname, $inputCallback );
3177                 } catch ( Exception $e ) {
3178                         fclose( $fp );
3179                         throw $e;
3180                 }
3181
3182                 fclose( $fp );
3183
3184                 return $error;
3185         }
3186
3187         public function setSchemaVars( $vars ) {
3188                 $this->mSchemaVars = $vars;
3189         }
3190
3191         /**
3192          * Read and execute commands from an open file handle.
3193          *
3194          * Returns true on success, error string or exception on failure (depending
3195          * on object's error ignore settings).
3196          *
3197          * @param resource $fp File handle
3198          * @param bool|callable $lineCallback Optional function called before reading each query
3199          * @param bool|callable $resultCallback Optional function called for each MySQL result
3200          * @param string $fname Calling function name
3201          * @param bool|callable $inputCallback Optional function called for each complete query sent
3202          * @return bool|string
3203          */
3204         public function sourceStream( $fp, $lineCallback = false, $resultCallback = false,
3205                 $fname = __METHOD__, $inputCallback = false
3206         ) {
3207                 $cmd = '';
3208
3209                 while ( !feof( $fp ) ) {
3210                         if ( $lineCallback ) {
3211                                 call_user_func( $lineCallback );
3212                         }
3213
3214                         $line = trim( fgets( $fp ) );
3215
3216                         if ( $line == '' ) {
3217                                 continue;
3218                         }
3219
3220                         if ( '-' == $line[0] && '-' == $line[1] ) {
3221                                 continue;
3222                         }
3223
3224                         if ( $cmd != '' ) {
3225                                 $cmd .= ' ';
3226                         }
3227
3228                         $done = $this->streamStatementEnd( $cmd, $line );
3229
3230                         $cmd .= "$line\n";
3231
3232                         if ( $done || feof( $fp ) ) {
3233                                 $cmd = $this->replaceVars( $cmd );
3234
3235                                 if ( ( $inputCallback && call_user_func( $inputCallback, $cmd ) ) || !$inputCallback ) {
3236                                         $res = $this->query( $cmd, $fname );
3237
3238                                         if ( $resultCallback ) {
3239                                                 call_user_func( $resultCallback, $res, $this );
3240                                         }
3241
3242                                         if ( false === $res ) {
3243                                                 $err = $this->lastError();
3244
3245                                                 return "Query \"{$cmd}\" failed with error code \"$err\".\n";
3246                                         }
3247                                 }
3248                                 $cmd = '';
3249                         }
3250                 }
3251
3252                 return true;
3253         }
3254
3255         /**
3256          * Called by sourceStream() to check if we've reached a statement end
3257          *
3258          * @param string $sql SQL assembled so far
3259          * @param string $newLine New line about to be added to $sql
3260          * @return bool Whether $newLine contains end of the statement
3261          */
3262         public function streamStatementEnd( &$sql, &$newLine ) {
3263                 if ( $this->delimiter ) {
3264                         $prev = $newLine;
3265                         $newLine = preg_replace( '/' . preg_quote( $this->delimiter, '/' ) . '$/', '', $newLine );
3266                         if ( $newLine != $prev ) {
3267                                 return true;
3268                         }
3269                 }
3270
3271                 return false;
3272         }
3273
3274         /**
3275          * Database independent variable replacement. Replaces a set of variables
3276          * in an SQL statement with their contents as given by $this->getSchemaVars().
3277          *
3278          * Supports '{$var}' `{$var}` and / *$var* / (without the spaces) style variables.
3279          *
3280          * - '{$var}' should be used for text and is passed through the database's
3281          *   addQuotes method.
3282          * - `{$var}` should be used for identifiers (e.g. table and database names).
3283          *   It is passed through the database's addIdentifierQuotes method which
3284          *   can be overridden if the database uses something other than backticks.
3285          * - / *_* / or / *$wgDBprefix* / passes the name that follows through the
3286          *   database's tableName method.
3287          * - / *i* / passes the name that follows through the database's indexName method.
3288          * - In all other cases, / *$var* / is left unencoded. Except for table options,
3289          *   its use should be avoided. In 1.24 and older, string encoding was applied.
3290          *
3291          * @param string $ins SQL statement to replace variables in
3292          * @return string The new SQL statement with variables replaced
3293          */
3294         protected function replaceVars( $ins ) {
3295                 $vars = $this->getSchemaVars();
3296                 return preg_replace_callback(
3297                         '!
3298                                 /\* (\$wgDBprefix|[_i]) \*/ (\w*) | # 1-2. tableName, indexName
3299                                 \'\{\$ (\w+) }\'                  | # 3. addQuotes
3300                                 `\{\$ (\w+) }`                    | # 4. addIdentifierQuotes
3301                                 /\*\$ (\w+) \*/                     # 5. leave unencoded
3302                         !x',
3303                         function ( $m ) use ( $vars ) {
3304                                 // Note: Because of <https://bugs.php.net/bug.php?id=51881>,
3305                                 // check for both nonexistent keys *and* the empty string.
3306                                 if ( isset( $m[1] ) && $m[1] !== '' ) {
3307                                         if ( $m[1] === 'i' ) {
3308                                                 return $this->indexName( $m[2] );
3309                                         } else {
3310                                                 return $this->tableName( $m[2] );
3311                                         }
3312                                 } elseif ( isset( $m[3] ) && $m[3] !== '' && array_key_exists( $m[3], $vars ) ) {
3313                                         return $this->addQuotes( $vars[$m[3]] );
3314                                 } elseif ( isset( $m[4] ) && $m[4] !== '' && array_key_exists( $m[4], $vars ) ) {
3315                                         return $this->addIdentifierQuotes( $vars[$m[4]] );
3316                                 } elseif ( isset( $m[5] ) && $m[5] !== '' && array_key_exists( $m[5], $vars ) ) {
3317                                         return $vars[$m[5]];
3318                                 } else {
3319                                         return $m[0];
3320                                 }
3321                         },
3322                         $ins
3323                 );
3324         }
3325
3326         /**
3327          * Get schema variables. If none have been set via setSchemaVars(), then
3328          * use some defaults from the current object.
3329          *
3330          * @return array
3331          */
3332         protected function getSchemaVars() {
3333                 if ( $this->mSchemaVars ) {
3334                         return $this->mSchemaVars;
3335                 } else {
3336                         return $this->getDefaultSchemaVars();
3337                 }
3338         }
3339
3340         /**
3341          * Get schema variables to use if none have been set via setSchemaVars().
3342          *
3343          * Override this in derived classes to provide variables for tables.sql
3344          * and SQL patch files.
3345          *
3346          * @return array
3347          */
3348         protected function getDefaultSchemaVars() {
3349                 return [];
3350         }
3351
3352         public function lockIsFree( $lockName, $method ) {
3353                 return true;
3354         }
3355
3356         public function lock( $lockName, $method, $timeout = 5 ) {
3357                 $this->mNamedLocksHeld[$lockName] = 1;
3358
3359                 return true;
3360         }
3361
3362         public function unlock( $lockName, $method ) {
3363                 unset( $this->mNamedLocksHeld[$lockName] );
3364
3365                 return true;
3366         }
3367
3368         public function getScopedLockAndFlush( $lockKey, $fname, $timeout ) {
3369                 if ( $this->writesOrCallbacksPending() ) {
3370                         // This only flushes transactions to clear snapshots, not to write data
3371                         $fnames = implode( ', ', $this->pendingWriteAndCallbackCallers() );
3372                         throw new DBUnexpectedError(
3373                                 $this,
3374                                 "$fname: Cannot COMMIT to clear snapshot because writes are pending ($fnames)."
3375                         );
3376                 }
3377
3378                 if ( !$this->lock( $lockKey, $fname, $timeout ) ) {
3379                         return null;
3380                 }
3381
3382                 $unlocker = new ScopedCallback( function () use ( $lockKey, $fname ) {
3383                         if ( $this->trxLevel() ) {
3384                                 // There is a good chance an exception was thrown, causing any early return
3385                                 // from the caller. Let any error handler get a chance to issue rollback().
3386                                 // If there isn't one, let the error bubble up and trigger server-side rollback.
3387                                 $this->onTransactionResolution(
3388                                         function () use ( $lockKey, $fname ) {
3389                                                 $this->unlock( $lockKey, $fname );
3390                                         },
3391                                         $fname
3392                                 );
3393                         } else {
3394                                 $this->unlock( $lockKey, $fname );
3395                         }
3396                 } );
3397
3398                 $this->commit( $fname, self::FLUSHING_INTERNAL );
3399
3400                 return $unlocker;
3401         }
3402
3403         public function namedLocksEnqueue() {
3404                 return false;
3405         }
3406
3407         /**
3408          * Lock specific tables
3409          *
3410          * @param array $read Array of tables to lock for read access
3411          * @param array $write Array of tables to lock for write access
3412          * @param string $method Name of caller
3413          * @param bool $lowPriority Whether to indicate writes to be LOW PRIORITY
3414          * @return bool
3415          */
3416         public function lockTables( $read, $write, $method, $lowPriority = true ) {
3417                 return true;
3418         }
3419
3420         /**
3421          * Unlock specific tables
3422          *
3423          * @param string $method The caller
3424          * @return bool
3425          */
3426         public function unlockTables( $method ) {
3427                 return true;
3428         }
3429
3430         /**
3431          * Delete a table
3432          * @param string $tableName
3433          * @param string $fName
3434          * @return bool|ResultWrapper
3435          * @since 1.18
3436          */
3437         public function dropTable( $tableName, $fName = __METHOD__ ) {
3438                 if ( !$this->tableExists( $tableName, $fName ) ) {
3439                         return false;
3440                 }
3441                 $sql = "DROP TABLE " . $this->tableName( $tableName ) . " CASCADE";
3442
3443                 return $this->query( $sql, $fName );
3444         }
3445
3446         public function getInfinity() {
3447                 return 'infinity';
3448         }
3449
3450         public function encodeExpiry( $expiry ) {
3451                 return ( $expiry == '' || $expiry == 'infinity' || $expiry == $this->getInfinity() )
3452                         ? $this->getInfinity()
3453                         : $this->timestamp( $expiry );
3454         }
3455
3456         public function decodeExpiry( $expiry, $format = TS_MW ) {
3457                 if ( $expiry == '' || $expiry == 'infinity' || $expiry == $this->getInfinity() ) {
3458                         return 'infinity';
3459                 }
3460
3461                 try {
3462                         $t = new ConvertableTimestamp( $expiry );
3463
3464                         return $t->getTimestamp( $format );
3465                 } catch ( TimestampException $e ) {
3466                         return false;
3467                 }
3468         }
3469
3470         public function setBigSelects( $value = true ) {
3471                 // no-op
3472         }
3473
3474         public function isReadOnly() {
3475                 return ( $this->getReadOnlyReason() !== false );
3476         }
3477
3478         /**
3479          * @return string|bool Reason this DB is read-only or false if it is not
3480          */
3481         protected function getReadOnlyReason() {
3482                 $reason = $this->getLBInfo( 'readOnlyReason' );
3483
3484                 return is_string( $reason ) ? $reason : false;
3485         }
3486
3487         public function setTableAliases( array $aliases ) {
3488                 $this->tableAliases = $aliases;
3489         }
3490
3491         /**
3492          * @return bool Whether a DB user is required to access the DB
3493          * @since 1.28
3494          */
3495         protected function requiresDatabaseUser() {
3496                 return true;
3497         }
3498
3499         /**
3500          * @since 1.19
3501          * @return string
3502          */
3503         public function __toString() {
3504                 return (string)$this->mConn;
3505         }
3506
3507         /**
3508          * Make sure that copies do not share the same client binding handle
3509          * @throws DBConnectionError
3510          */
3511         public function __clone() {
3512                 $this->connLogger->warning(
3513                         "Cloning " . get_class( $this ) . " is not recomended; forking connection:\n" .
3514                         ( new RuntimeException() )->getTraceAsString()
3515                 );
3516
3517                 if ( $this->isOpen() ) {
3518                         // Open a new connection resource without messing with the old one
3519                         $this->mOpened = false;
3520                         $this->mConn = false;
3521                         $this->mTrxLevel = 0; // no trx anymore
3522                         $this->open( $this->mServer, $this->mUser, $this->mPassword, $this->mDBname );
3523                         $this->lastPing = microtime( true );
3524                 }
3525         }
3526
3527         /**
3528          * Called by serialize. Throw an exception when DB connection is serialized.
3529          * This causes problems on some database engines because the connection is
3530          * not restored on unserialize.
3531          */
3532         public function __sleep() {
3533                 throw new RuntimeException( 'Database serialization may cause problems, since ' .
3534                         'the connection is not restored on wakeup.' );
3535         }
3536
3537         /**
3538          * Run a few simple sanity checks and close dangling connections
3539          */
3540         public function __destruct() {
3541                 if ( $this->mTrxLevel && $this->mTrxDoneWrites ) {
3542                         trigger_error( "Uncommitted DB writes (transaction from {$this->mTrxFname})." );
3543                 }
3544
3545                 $danglingWriters = $this->pendingWriteAndCallbackCallers();
3546                 if ( $danglingWriters ) {
3547                         $fnames = implode( ', ', $danglingWriters );
3548                         trigger_error( "DB transaction writes or callbacks still pending ($fnames)." );
3549                 }
3550
3551                 if ( $this->mConn ) {
3552                         // Avoid connection leaks for sanity
3553                         $this->closeConnection();
3554                         $this->mConn = false;
3555                         $this->mOpened = false;
3556                 }
3557         }
3558 }