includes/libs/rdbms/database/Database.php

   1 <?php
   2 /**
   3  * @defgroup Database Database
   4  *
   5  * This file deals with database interface functions
   6  * and query specifics/optimisations.
   7  *
   8  * This program is free software; you can redistribute it and/or modify
   9  * it under the terms of the GNU General Public License as published by
  10  * the Free Software Foundation; either version 2 of the License, or
  11  * (at your option) any later version.
  12  *
  13  * This program is distributed in the hope that it will be useful,
  14  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  15  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
  16  * GNU General Public License for more details.
  17  *
  18  * You should have received a copy of the GNU General Public License along
  19  * with this program; if not, write to the Free Software Foundation, Inc.,
  20  * 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
  21  * http://www.gnu.org/copyleft/gpl.html
  22  *
  23  * @file
  24  * @ingroup Database
  25  */
  26 use Psr\Log\LoggerAwareInterface;
  27 use Psr\Log\LoggerInterface;
  28 use Wikimedia\ScopedCallback;
  29 use Wikimedia\Rdbms\TransactionProfiler;
  30 use Wikimedia\Rdbms\LikeMatch;
  31 use Wikimedia\Rdbms\DatabaseDomain;
  32 use Wikimedia\Rdbms\ResultWrapper;
  33 use Wikimedia\Rdbms\DBMasterPos;
  34 use Wikimedia\Rdbms\Blob;
  35 use Wikimedia\Timestamp\ConvertibleTimestamp;
  36
  37 /**
  38  * Relational database abstraction object
  39  *
  40  * @ingroup Database
  41  * @since 1.28
  42  */
  43 abstract class Database implements IDatabase, IMaintainableDatabase, LoggerAwareInterface {
  44         /** Number of times to re-try an operation in case of deadlock */
  45         const DEADLOCK_TRIES = 4;
  46         /** Minimum time to wait before retry, in microseconds */
  47         const DEADLOCK_DELAY_MIN = 500000;
  48         /** Maximum time to wait before retry */
  49         const DEADLOCK_DELAY_MAX = 1500000;
  50
  51         /** How long before it is worth doing a dummy query to test the connection */
  52         const PING_TTL = 1.0;
  53         const PING_QUERY = 'SELECT 1 AS ping';
  54
  55         const TINY_WRITE_SEC = .010;
  56         const SLOW_WRITE_SEC = .500;
  57         const SMALL_WRITE_ROWS = 100;
  58
  59         /** @var string SQL query */
  60         protected $mLastQuery = '';
  61         /** @var float|bool UNIX timestamp of last write query */
  62         protected $mLastWriteTime = false;
  63         /** @var string|bool */
  64         protected $mPHPError = false;
  65         /** @var string */
  66         protected $mServer;
  67         /** @var string */
  68         protected $mUser;
  69         /** @var string */
  70         protected $mPassword;
  71         /** @var string */
  72         protected $mDBname;
  73         /** @var array[] $aliases Map of (table => (dbname, schema, prefix) map) */
  74         protected $tableAliases = [];
  75         /** @var bool Whether this PHP instance is for a CLI script */
  76         protected $cliMode;
  77         /** @var string Agent name for query profiling */
  78         protected $agent;
  79
  80         /** @var BagOStuff APC cache */
  81         protected $srvCache;
  82         /** @var LoggerInterface */
  83         protected $connLogger;
  84         /** @var LoggerInterface */
  85         protected $queryLogger;
  86         /** @var callback Error logging callback */
  87         protected $errorLogger;
  88
  89         /** @var resource|null Database connection */
  90         protected $mConn = null;
  91         /** @var bool */
  92         protected $mOpened = false;
  93
  94         /** @var array[] List of (callable, method name) */
  95         protected $mTrxIdleCallbacks = [];
  96         /** @var array[] List of (callable, method name) */
  97         protected $mTrxPreCommitCallbacks = [];
  98         /** @var array[] List of (callable, method name) */
  99         protected $mTrxEndCallbacks = [];
 100         /** @var callable[] Map of (name => callable) */
 101         protected $mTrxRecurringCallbacks = [];
 102         /** @var bool Whether to suppress triggering of transaction end callbacks */
 103         protected $mTrxEndCallbacksSuppressed = false;
 104
 105         /** @var string */
 106         protected $mTablePrefix = '';
 107         /** @var string */
 108         protected $mSchema = '';
 109         /** @var integer */
 110         protected $mFlags;
 111         /** @var array */
 112         protected $mLBInfo = [];
 113         /** @var bool|null */
 114         protected $mDefaultBigSelects = null;
 115         /** @var array|bool */
 116         protected $mSchemaVars = false;
 117         /** @var array */
 118         protected $mSessionVars = [];
 119         /** @var array|null */
 120         protected $preparedArgs;
 121         /** @var string|bool|null Stashed value of html_errors INI setting */
 122         protected $htmlErrors;
 123         /** @var string */
 124         protected $delimiter = ';';
 125         /** @var DatabaseDomain */
 126         protected $currentDomain;
 127
 128         /**
 129          * Either 1 if a transaction is active or 0 otherwise.
 130          * The other Trx fields may not be meaningfull if this is 0.
 131          *
 132          * @var int
 133          */
 134         protected $mTrxLevel = 0;
 135         /**
 136          * Either a short hexidecimal string if a transaction is active or ""
 137          *
 138          * @var string
 139          * @see Database::mTrxLevel
 140          */
 141         protected $mTrxShortId = '';
 142         /**
 143          * The UNIX time that the transaction started. Callers can assume that if
 144          * snapshot isolation is used, then the data is *at least* up to date to that
 145          * point (possibly more up-to-date since the first SELECT defines the snapshot).
 146          *
 147          * @var float|null
 148          * @see Database::mTrxLevel
 149          */
 150         private $mTrxTimestamp = null;
 151         /** @var float Lag estimate at the time of BEGIN */
 152         private $mTrxReplicaLag = null;
 153         /**
 154          * Remembers the function name given for starting the most recent transaction via begin().
 155          * Used to provide additional context for error reporting.
 156          *
 157          * @var string
 158          * @see Database::mTrxLevel
 159          */
 160         private $mTrxFname = null;
 161         /**
 162          * Record if possible write queries were done in the last transaction started
 163          *
 164          * @var bool
 165          * @see Database::mTrxLevel
 166          */
 167         private $mTrxDoneWrites = false;
 168         /**
 169          * Record if the current transaction was started implicitly due to DBO_TRX being set.
 170          *
 171          * @var bool
 172          * @see Database::mTrxLevel
 173          */
 174         private $mTrxAutomatic = false;
 175         /**
 176          * Array of levels of atomicity within transactions
 177          *
 178          * @var array
 179          */
 180         private $mTrxAtomicLevels = [];
 181         /**
 182          * Record if the current transaction was started implicitly by Database::startAtomic
 183          *
 184          * @var bool
 185          */
 186         private $mTrxAutomaticAtomic = false;
 187         /**
 188          * Track the write query callers of the current transaction
 189          *
 190          * @var string[]
 191          */
 192         private $mTrxWriteCallers = [];
 193         /**
 194          * @var float Seconds spent in write queries for the current transaction
 195          */
 196         private $mTrxWriteDuration = 0.0;
 197         /**
 198          * @var integer Number of write queries for the current transaction
 199          */
 200         private $mTrxWriteQueryCount = 0;
 201         /**
 202          * @var float Like mTrxWriteQueryCount but excludes lock-bound, easy to replicate, queries
 203          */
 204         private $mTrxWriteAdjDuration = 0.0;
 205         /**
 206          * @var integer Number of write queries counted in mTrxWriteAdjDuration
 207          */
 208         private $mTrxWriteAdjQueryCount = 0;
 209         /**
 210          * @var float RTT time estimate
 211          */
 212         private $mRTTEstimate = 0.0;
 213
 214         /** @var array Map of (name => 1) for locks obtained via lock() */
 215         private $mNamedLocksHeld = [];
 216         /** @var array Map of (table name => 1) for TEMPORARY tables */
 217         protected $mSessionTempTables = [];
 218
 219         /** @var IDatabase|null Lazy handle to the master DB this server replicates from */
 220         private $lazyMasterHandle;
 221
 222         /** @var float UNIX timestamp */
 223         protected $lastPing = 0.0;
 224
 225         /** @var int[] Prior mFlags values */
 226         private $priorFlags = [];
 227
 228         /** @var object|string Class name or object With profileIn/profileOut methods */
 229         protected $profiler;
 230         /** @var TransactionProfiler */
 231         protected $trxProfiler;
 232
 233         /**
 234          * Constructor and database handle and attempt to connect to the DB server
 235          *
 236          * IDatabase classes should not be constructed directly in external
 237          * code. Database::factory() should be used instead.
 238          *
 239          * @param array $params Parameters passed from Database::factory()
 240          */
 241         function __construct( array $params ) {
 242                 $server = $params['host'];
 243                 $user = $params['user'];
 244                 $password = $params['password'];
 245                 $dbName = $params['dbname'];
 246
 247                 $this->mSchema = $params['schema'];
 248                 $this->mTablePrefix = $params['tablePrefix'];
 249
 250                 $this->cliMode = $params['cliMode'];
 251                 // Agent name is added to SQL queries in a comment, so make sure it can't break out
 252                 $this->agent = str_replace( '/', '-', $params['agent'] );
 253
 254                 $this->mFlags = $params['flags'];
 255                 if ( $this->mFlags & self::DBO_DEFAULT ) {
 256                         if ( $this->cliMode ) {
 257                                 $this->mFlags &= ~self::DBO_TRX;
 258                         } else {
 259                                 $this->mFlags |= self::DBO_TRX;
 260                         }
 261                 }
 262
 263                 $this->mSessionVars = $params['variables'];
 264
 265                 $this->srvCache = isset( $params['srvCache'] )
 266                         ? $params['srvCache']
 267                         : new HashBagOStuff();
 268
 269                 $this->profiler = $params['profiler'];
 270                 $this->trxProfiler = $params['trxProfiler'];
 271                 $this->connLogger = $params['connLogger'];
 272                 $this->queryLogger = $params['queryLogger'];
 273                 $this->errorLogger = $params['errorLogger'];
 274
 275                 // Set initial dummy domain until open() sets the final DB/prefix
 276                 $this->currentDomain = DatabaseDomain::newUnspecified();
 277
 278                 if ( $user ) {
 279                         $this->open( $server, $user, $password, $dbName );
 280                 } elseif ( $this->requiresDatabaseUser() ) {
 281                         throw new InvalidArgumentException( "No database user provided." );
 282                 }
 283
 284                 // Set the domain object after open() sets the relevant fields
 285                 if ( $this->mDBname != '' ) {
 286                         // Domains with server scope but a table prefix are not used by IDatabase classes
 287                         $this->currentDomain = new DatabaseDomain( $this->mDBname, null, $this->mTablePrefix );
 288                 }
 289         }
 290
 291         /**
 292          * Construct a Database subclass instance given a database type and parameters
 293          *
 294          * This also connects to the database immediately upon object construction
 295          *
 296          * @param string $dbType A possible DB type (sqlite, mysql, postgres)
 297          * @param array $p Parameter map with keys:
 298          *   - host : The hostname of the DB server
 299          *   - user : The name of the database user the client operates under
 300          *   - password : The password for the database user
 301          *   - dbname : The name of the database to use where queries do not specify one.
 302          *      The database must exist or an error might be thrown. Setting this to the empty string
 303          *      will avoid any such errors and make the handle have no implicit database scope. This is
 304          *      useful for queries like SHOW STATUS, CREATE DATABASE, or DROP DATABASE. Note that a
 305          *      "database" in Postgres is rougly equivalent to an entire MySQL server. This the domain
 306          *      in which user names and such are defined, e.g. users are database-specific in Postgres.
 307          *   - schema : The database schema to use (if supported). A "schema" in Postgres is roughly
 308          *      equivalent to a "database" in MySQL. Note that MySQL and SQLite do not use schemas.
 309          *   - tablePrefix : Optional table prefix that is implicitly added on to all table names
 310          *      recognized in queries. This can be used in place of schemas for handle site farms.
 311          *   - flags : Optional bitfield of DBO_* constants that define connection, protocol,
 312          *      buffering, and transaction behavior. It is STRONGLY adviced to leave the DBO_DEFAULT
 313          *      flag in place UNLESS this this database simply acts as a key/value store.
 314          *   - driver: Optional name of a specific DB client driver. For MySQL, there is the old
 315          *      'mysql' driver and the newer 'mysqli' driver.
 316          *   - variables: Optional map of session variables to set after connecting. This can be
 317          *      used to adjust lock timeouts or encoding modes and the like.
 318          *   - connLogger: Optional PSR-3 logger interface instance.
 319          *   - queryLogger: Optional PSR-3 logger interface instance.
 320          *   - profiler: Optional class name or object with profileIn()/profileOut() methods.
 321          *      These will be called in query(), using a simplified version of the SQL that also
 322          *      includes the agent as a SQL comment.
 323          *   - trxProfiler: Optional TransactionProfiler instance.
 324          *   - errorLogger: Optional callback that takes an Exception and logs it.
 325          *   - cliMode: Whether to consider the execution context that of a CLI script.
 326          *   - agent: Optional name used to identify the end-user in query profiling/logging.
 327          *   - srvCache: Optional BagOStuff instance to an APC-style cache.
 328          * @return Database|null If the database driver or extension cannot be found
 329          * @throws InvalidArgumentException If the database driver or extension cannot be found
 330          * @since 1.18
 331          */
 332         final public static function factory( $dbType, $p = [] ) {
 333                 static $canonicalDBTypes = [
 334                         'mysql' => [ 'mysqli', 'mysql' ],
 335                         'postgres' => [],
 336                         'sqlite' => [],
 337                         'oracle' => [],
 338                         'mssql' => [],
 339                 ];
 340
 341                 $driver = false;
 342                 $dbType = strtolower( $dbType );
 343                 if ( isset( $canonicalDBTypes[$dbType] ) && $canonicalDBTypes[$dbType] ) {
 344                         $possibleDrivers = $canonicalDBTypes[$dbType];
 345                         if ( !empty( $p['driver'] ) ) {
 346                                 if ( in_array( $p['driver'], $possibleDrivers ) ) {
 347                                         $driver = $p['driver'];
 348                                 } else {
 349                                         throw new InvalidArgumentException( __METHOD__ .
 350                                                 " type '$dbType' does not support driver '{$p['driver']}'" );
 351                                 }
 352                         } else {
 353                                 foreach ( $possibleDrivers as $posDriver ) {
 354                                         if ( extension_loaded( $posDriver ) ) {
 355                                                 $driver = $posDriver;
 356                                                 break;
 357                                         }
 358                                 }
 359                         }
 360                 } else {
 361                         $driver = $dbType;
 362                 }
 363                 if ( $driver === false || $driver === '' ) {
 364                         throw new InvalidArgumentException( __METHOD__ .
 365                                 " no viable database extension found for type '$dbType'" );
 366                 }
 367
 368                 $class = 'Database' . ucfirst( $driver );
 369                 if ( class_exists( $class ) && is_subclass_of( $class, 'IDatabase' ) ) {
 370                         // Resolve some defaults for b/c
 371                         $p['host'] = isset( $p['host'] ) ? $p['host'] : false;
 372                         $p['user'] = isset( $p['user'] ) ? $p['user'] : false;
 373                         $p['password'] = isset( $p['password'] ) ? $p['password'] : false;
 374                         $p['dbname'] = isset( $p['dbname'] ) ? $p['dbname'] : false;
 375                         $p['flags'] = isset( $p['flags'] ) ? $p['flags'] : 0;
 376                         $p['variables'] = isset( $p['variables'] ) ? $p['variables'] : [];
 377                         $p['tablePrefix'] = isset( $p['tablePrefix'] ) ? $p['tablePrefix'] : '';
 378                         $p['schema'] = isset( $p['schema'] ) ? $p['schema'] : '';
 379                         $p['cliMode'] = isset( $p['cliMode'] ) ? $p['cliMode'] : ( PHP_SAPI === 'cli' );
 380                         $p['agent'] = isset( $p['agent'] ) ? $p['agent'] : '';
 381                         if ( !isset( $p['connLogger'] ) ) {
 382                                 $p['connLogger'] = new \Psr\Log\NullLogger();
 383                         }
 384                         if ( !isset( $p['queryLogger'] ) ) {
 385                                 $p['queryLogger'] = new \Psr\Log\NullLogger();
 386                         }
 387                         $p['profiler'] = isset( $p['profiler'] ) ? $p['profiler'] : null;
 388                         if ( !isset( $p['trxProfiler'] ) ) {
 389                                 $p['trxProfiler'] = new TransactionProfiler();
 390                         }
 391                         if ( !isset( $p['errorLogger'] ) ) {
 392                                 $p['errorLogger'] = function ( Exception $e ) {
 393                                         trigger_error( get_class( $e ) . ': ' . $e->getMessage(), E_USER_WARNING );
 394                                 };
 395                         }
 396
 397                         $conn = new $class( $p );
 398                 } else {
 399                         $conn = null;
 400                 }
 401
 402                 return $conn;
 403         }
 404
 405         public function setLogger( LoggerInterface $logger ) {
 406                 $this->queryLogger = $logger;
 407         }
 408
 409         public function getServerInfo() {
 410                 return $this->getServerVersion();
 411         }
 412
 413         public function bufferResults( $buffer = null ) {
 414                 $res = !$this->getFlag( self::DBO_NOBUFFER );
 415                 if ( $buffer !== null ) {
 416                         $buffer
 417                                 ? $this->clearFlag( self::DBO_NOBUFFER )
 418                                 : $this->setFlag( self::DBO_NOBUFFER );
 419                 }
 420
 421                 return $res;
 422         }
 423
 424         /**
 425          * Turns on (false) or off (true) the automatic generation and sending
 426          * of a "we're sorry, but there has been a database error" page on
 427          * database errors. Default is on (false). When turned off, the
 428          * code should use lastErrno() and lastError() to handle the
 429          * situation as appropriate.
 430          *
 431          * Do not use this function outside of the Database classes.
 432          *
 433          * @param null|bool $ignoreErrors
 434          * @return bool The previous value of the flag.
 435          */
 436         protected function ignoreErrors( $ignoreErrors = null ) {
 437                 $res = $this->getFlag( self::DBO_IGNORE );
 438                 if ( $ignoreErrors !== null ) {
 439                         $ignoreErrors
 440                                 ? $this->setFlag( self::DBO_IGNORE )
 441                                 : $this->clearFlag( self::DBO_IGNORE );
 442                 }
 443
 444                 return $res;
 445         }
 446
 447         public function trxLevel() {
 448                 return $this->mTrxLevel;
 449         }
 450
 451         public function trxTimestamp() {
 452                 return $this->mTrxLevel ? $this->mTrxTimestamp : null;
 453         }
 454
 455         public function tablePrefix( $prefix = null ) {
 456                 $old = $this->mTablePrefix;
 457                 if ( $prefix !== null ) {
 458                         $this->mTablePrefix = $prefix;
 459                         $this->currentDomain = ( $this->mDBname != '' )
 460                                 ? new DatabaseDomain( $this->mDBname, null, $this->mTablePrefix )
 461                                 : DatabaseDomain::newUnspecified();
 462                 }
 463
 464                 return $old;
 465         }
 466
 467         public function dbSchema( $schema = null ) {
 468                 $old = $this->mSchema;
 469                 if ( $schema !== null ) {
 470                         $this->mSchema = $schema;
 471                 }
 472
 473                 return $old;
 474         }
 475
 476         public function getLBInfo( $name = null ) {
 477                 if ( is_null( $name ) ) {
 478                         return $this->mLBInfo;
 479                 } else {
 480                         if ( array_key_exists( $name, $this->mLBInfo ) ) {
 481                                 return $this->mLBInfo[$name];
 482                         } else {
 483                                 return null;
 484                         }
 485                 }
 486         }
 487
 488         public function setLBInfo( $name, $value = null ) {
 489                 if ( is_null( $value ) ) {
 490                         $this->mLBInfo = $name;
 491                 } else {
 492                         $this->mLBInfo[$name] = $value;
 493                 }
 494         }
 495
 496         public function setLazyMasterHandle( IDatabase $conn ) {
 497                 $this->lazyMasterHandle = $conn;
 498         }
 499
 500         /**
 501          * @return IDatabase|null
 502          * @see setLazyMasterHandle()
 503          * @since 1.27
 504          */
 505         protected function getLazyMasterHandle() {
 506                 return $this->lazyMasterHandle;
 507         }
 508
 509         public function implicitGroupby() {
 510                 return true;
 511         }
 512
 513         public function implicitOrderby() {
 514                 return true;
 515         }
 516
 517         public function lastQuery() {
 518                 return $this->mLastQuery;
 519         }
 520
 521         public function doneWrites() {
 522                 return (bool)$this->mLastWriteTime;
 523         }
 524
 525         public function lastDoneWrites() {
 526                 return $this->mLastWriteTime ?: false;
 527         }
 528
 529         public function writesPending() {
 530                 return $this->mTrxLevel && $this->mTrxDoneWrites;
 531         }
 532
 533         public function writesOrCallbacksPending() {
 534                 return $this->mTrxLevel && (
 535                         $this->mTrxDoneWrites || $this->mTrxIdleCallbacks || $this->mTrxPreCommitCallbacks
 536                 );
 537         }
 538
 539         public function pendingWriteQueryDuration( $type = self::ESTIMATE_TOTAL ) {
 540                 if ( !$this->mTrxLevel ) {
 541                         return false;
 542                 } elseif ( !$this->mTrxDoneWrites ) {
 543                         return 0.0;
 544                 }
 545
 546                 switch ( $type ) {
 547                         case self::ESTIMATE_DB_APPLY:
 548                                 $this->ping( $rtt );
 549                                 $rttAdjTotal = $this->mTrxWriteAdjQueryCount * $rtt;
 550                                 $applyTime = max( $this->mTrxWriteAdjDuration - $rttAdjTotal, 0 );
 551                                 // For omitted queries, make them count as something at least
 552                                 $omitted = $this->mTrxWriteQueryCount - $this->mTrxWriteAdjQueryCount;
 553                                 $applyTime += self::TINY_WRITE_SEC * $omitted;
 554
 555                                 return $applyTime;
 556                         default: // everything
 557                                 return $this->mTrxWriteDuration;
 558                 }
 559         }
 560
 561         public function pendingWriteCallers() {
 562                 return $this->mTrxLevel ? $this->mTrxWriteCallers : [];
 563         }
 564
 565         protected function pendingWriteAndCallbackCallers() {
 566                 if ( !$this->mTrxLevel ) {
 567                         return [];
 568                 }
 569
 570                 $fnames = $this->mTrxWriteCallers;
 571                 foreach ( [
 572                         $this->mTrxIdleCallbacks,
 573                         $this->mTrxPreCommitCallbacks,
 574                         $this->mTrxEndCallbacks
 575                 ] as $callbacks ) {
 576                         foreach ( $callbacks as $callback ) {
 577                                 $fnames[] = $callback[1];
 578                         }
 579                 }
 580
 581                 return $fnames;
 582         }
 583
 584         public function isOpen() {
 585                 return $this->mOpened;
 586         }
 587
 588         public function setFlag( $flag, $remember = self::REMEMBER_NOTHING ) {
 589                 if ( $remember === self::REMEMBER_PRIOR ) {
 590                         array_push( $this->priorFlags, $this->mFlags );
 591                 }
 592                 $this->mFlags |= $flag;
 593         }
 594
 595         public function clearFlag( $flag, $remember = self::REMEMBER_NOTHING ) {
 596                 if ( $remember === self::REMEMBER_PRIOR ) {
 597                         array_push( $this->priorFlags, $this->mFlags );
 598                 }
 599                 $this->mFlags &= ~$flag;
 600         }
 601
 602         public function restoreFlags( $state = self::RESTORE_PRIOR ) {
 603                 if ( !$this->priorFlags ) {
 604                         return;
 605                 }
 606
 607                 if ( $state === self::RESTORE_INITIAL ) {
 608                         $this->mFlags = reset( $this->priorFlags );
 609                         $this->priorFlags = [];
 610                 } else {
 611                         $this->mFlags = array_pop( $this->priorFlags );
 612                 }
 613         }
 614
 615         public function getFlag( $flag ) {
 616                 return !!( $this->mFlags & $flag );
 617         }
 618
 619         /**
 620          * @param string $name Class field name
 621          * @return mixed
 622          * @deprecated Since 1.28
 623          */
 624         public function getProperty( $name ) {
 625                 return $this->$name;
 626         }
 627
 628         public function getDomainID() {
 629                 return $this->currentDomain->getId();
 630         }
 631
 632         final public function getWikiID() {
 633                 return $this->getDomainID();
 634         }
 635
 636         /**
 637          * Get information about an index into an object
 638          * @param string $table Table name
 639          * @param string $index Index name
 640          * @param string $fname Calling function name
 641          * @return mixed Database-specific index description class or false if the index does not exist
 642          */
 643         abstract function indexInfo( $table, $index, $fname = __METHOD__ );
 644
 645         /**
 646          * Wrapper for addslashes()
 647          *
 648          * @param string $s String to be slashed.
 649          * @return string Slashed string.
 650          */
 651         abstract function strencode( $s );
 652
 653         protected function installErrorHandler() {
 654                 $this->mPHPError = false;
 655                 $this->htmlErrors = ini_set( 'html_errors', '0' );
 656                 set_error_handler( [ $this, 'connectionErrorLogger' ] );
 657         }
 658
 659         /**
 660          * @return bool|string
 661          */
 662         protected function restoreErrorHandler() {
 663                 restore_error_handler();
 664                 if ( $this->htmlErrors !== false ) {
 665                         ini_set( 'html_errors', $this->htmlErrors );
 666                 }
 667
 668                 return $this->getLastPHPError();
 669         }
 670
 671         /**
 672          * @return string|bool Last PHP error for this DB (typically connection errors)
 673          */
 674         protected function getLastPHPError() {
 675                 if ( $this->mPHPError ) {
 676                         $error = preg_replace( '!\[<a.*</a>\]!', '', $this->mPHPError );
 677                         $error = preg_replace( '!^.*?:\s?(.*)$!', '$1', $error );
 678
 679                         return $error;
 680                 }
 681
 682                 return false;
 683         }
 684
 685         /**
 686          * This method should not be used outside of Database classes
 687          *
 688          * @param int $errno
 689          * @param string $errstr
 690          */
 691         public function connectionErrorLogger( $errno, $errstr ) {
 692                 $this->mPHPError = $errstr;
 693         }
 694
 695         /**
 696          * Create a log context to pass to PSR-3 logger functions.
 697          *
 698          * @param array $extras Additional data to add to context
 699          * @return array
 700          */
 701         protected function getLogContext( array $extras = [] ) {
 702                 return array_merge(
 703                         [
 704                                 'db_server' => $this->mServer,
 705                                 'db_name' => $this->mDBname,
 706                                 'db_user' => $this->mUser,
 707                         ],
 708                         $extras
 709                 );
 710         }
 711
 712         public function close() {
 713                 if ( $this->mConn ) {
 714                         if ( $this->trxLevel() ) {
 715                                 $this->commit( __METHOD__, self::FLUSHING_INTERNAL );
 716                         }
 717
 718                         $closed = $this->closeConnection();
 719                         $this->mConn = false;
 720                 } elseif ( $this->mTrxIdleCallbacks || $this->mTrxEndCallbacks ) { // sanity
 721                         throw new RuntimeException( "Transaction callbacks still pending." );
 722                 } else {
 723                         $closed = true;
 724                 }
 725                 $this->mOpened = false;
 726
 727                 return $closed;
 728         }
 729
 730         /**
 731          * Make sure isOpen() returns true as a sanity check
 732          *
 733          * @throws DBUnexpectedError
 734          */
 735         protected function assertOpen() {
 736                 if ( !$this->isOpen() ) {
 737                         throw new DBUnexpectedError( $this, "DB connection was already closed." );
 738                 }
 739         }
 740
 741         /**
 742          * Closes underlying database connection
 743          * @since 1.20
 744          * @return bool Whether connection was closed successfully
 745          */
 746         abstract protected function closeConnection();
 747
 748         public function reportConnectionError( $error = 'Unknown error' ) {
 749                 $myError = $this->lastError();
 750                 if ( $myError ) {
 751                         $error = $myError;
 752                 }
 753
 754                 # New method
 755                 throw new DBConnectionError( $this, $error );
 756         }
 757
 758         /**
 759          * The DBMS-dependent part of query()
 760          *
 761          * @param string $sql SQL query.
 762          * @return ResultWrapper|bool Result object to feed to fetchObject,
 763          *   fetchRow, ...; or false on failure
 764          */
 765         abstract protected function doQuery( $sql );
 766
 767         /**
 768          * Determine whether a query writes to the DB.
 769          * Should return true if unsure.
 770          *
 771          * @param string $sql
 772          * @return bool
 773          */
 774         protected function isWriteQuery( $sql ) {
 775                 return !preg_match(
 776                         '/^(?:SELECT|BEGIN|ROLLBACK|COMMIT|SET|SHOW|EXPLAIN|\(SELECT)\b/i', $sql );
 777         }
 778
 779         /**
 780          * @param $sql
 781          * @return string|null
 782          */
 783         protected function getQueryVerb( $sql ) {
 784                 return preg_match( '/^\s*([a-z]+)/i', $sql, $m ) ? strtoupper( $m[1] ) : null;
 785         }
 786
 787         /**
 788          * Determine whether a SQL statement is sensitive to isolation level.
 789          * A SQL statement is considered transactable if its result could vary
 790          * depending on the transaction isolation level. Operational commands
 791          * such as 'SET' and 'SHOW' are not considered to be transactable.
 792          *
 793          * @param string $sql
 794          * @return bool
 795          */
 796         protected function isTransactableQuery( $sql ) {
 797                 return !in_array(
 798                         $this->getQueryVerb( $sql ),
 799                         [ 'BEGIN', 'COMMIT', 'ROLLBACK', 'SHOW', 'SET', 'CREATE', 'ALTER' ],
 800                         true
 801                 );
 802         }
 803
 804         /**
 805          * @param string $sql A SQL query
 806          * @return bool Whether $sql is SQL for creating/dropping a new TEMPORARY table
 807          */
 808         protected function registerTempTableOperation( $sql ) {
 809                 if ( preg_match(
 810                         '/^CREATE\s+TEMPORARY\s+TABLE\s+(?:IF\s+NOT\s+EXISTS\s+)?[`"\']?(\w+)[`"\']?/i',
 811                         $sql,
 812                         $matches
 813                 ) ) {
 814                         $this->mSessionTempTables[$matches[1]] = 1;
 815
 816                         return true;
 817                 } elseif ( preg_match(
 818                         '/^DROP\s+(?:TEMPORARY\s+)?TABLE\s+(?:IF\s+EXISTS\s+)?[`"\']?(\w+)[`"\']?/i',
 819                         $sql,
 820                         $matches
 821                 ) ) {
 822                         unset( $this->mSessionTempTables[$matches[1]] );
 823
 824                         return true;
 825                 } elseif ( preg_match(
 826                         '/^(?:INSERT\s+(?:\w+\s+)?INTO|UPDATE|DELETE\s+FROM)\s+[`"\']?(\w+)[`"\']?/i',
 827                         $sql,
 828                         $matches
 829                 ) ) {
 830                         return isset( $this->mSessionTempTables[$matches[1]] );
 831                 }
 832
 833                 return false;
 834         }
 835
 836         public function query( $sql, $fname = __METHOD__, $tempIgnore = false ) {
 837                 $priorWritesPending = $this->writesOrCallbacksPending();
 838                 $this->mLastQuery = $sql;
 839
 840                 $isWrite = $this->isWriteQuery( $sql ) && !$this->registerTempTableOperation( $sql );
 841                 if ( $isWrite ) {
 842                         $reason = $this->getReadOnlyReason();
 843                         if ( $reason !== false ) {
 844                                 throw new DBReadOnlyError( $this, "Database is read-only: $reason" );
 845                         }
 846                         # Set a flag indicating that writes have been done
 847                         $this->mLastWriteTime = microtime( true );
 848                 }
 849
 850                 // Add trace comment to the begin of the sql string, right after the operator.
 851                 // Or, for one-word queries (like "BEGIN" or COMMIT") add it to the end (T44598)
 852                 $commentedSql = preg_replace( '/\s|$/', " /* $fname {$this->agent} */ ", $sql, 1 );
 853
 854                 # Start implicit transactions that wrap the request if DBO_TRX is enabled
 855                 if ( !$this->mTrxLevel && $this->getFlag( self::DBO_TRX )
 856                         && $this->isTransactableQuery( $sql )
 857                 ) {
 858                         $this->begin( __METHOD__ . " ($fname)", self::TRANSACTION_INTERNAL );
 859                         $this->mTrxAutomatic = true;
 860                 }
 861
 862                 # Keep track of whether the transaction has write queries pending
 863                 if ( $this->mTrxLevel && !$this->mTrxDoneWrites && $isWrite ) {
 864                         $this->mTrxDoneWrites = true;
 865                         $this->trxProfiler->transactionWritingIn(
 866                                 $this->mServer, $this->mDBname, $this->mTrxShortId );
 867                 }
 868
 869                 if ( $this->getFlag( self::DBO_DEBUG ) ) {
 870                         $this->queryLogger->debug( "{$this->mDBname} {$commentedSql}" );
 871                 }
 872
 873                 # Avoid fatals if close() was called
 874                 $this->assertOpen();
 875
 876                 # Send the query to the server
 877                 $ret = $this->doProfiledQuery( $sql, $commentedSql, $isWrite, $fname );
 878
 879                 # Try reconnecting if the connection was lost
 880                 if ( false === $ret && $this->wasErrorReissuable() ) {
 881                         $recoverable = $this->canRecoverFromDisconnect( $sql, $priorWritesPending );
 882                         # Stash the last error values before anything might clear them
 883                         $lastError = $this->lastError();
 884                         $lastErrno = $this->lastErrno();
 885                         # Update state tracking to reflect transaction loss due to disconnection
 886                         $this->handleSessionLoss();
 887                         if ( $this->reconnect() ) {
 888                                 $msg = __METHOD__ . ": lost connection to {$this->getServer()}; reconnected";
 889                                 $this->connLogger->warning( $msg );
 890                                 $this->queryLogger->warning(
 891                                         "$msg:\n" . ( new RuntimeException() )->getTraceAsString() );
 892
 893                                 if ( !$recoverable ) {
 894                                         # Callers may catch the exception and continue to use the DB
 895                                         $this->reportQueryError( $lastError, $lastErrno, $sql, $fname );
 896                                 } else {
 897                                         # Should be safe to silently retry the query
 898                                         $ret = $this->doProfiledQuery( $sql, $commentedSql, $isWrite, $fname );
 899                                 }
 900                         } else {
 901                                 $msg = __METHOD__ . ": lost connection to {$this->getServer()} permanently";
 902                                 $this->connLogger->error( $msg );
 903                         }
 904                 }
 905
 906                 if ( false === $ret ) {
 907                         # Deadlocks cause the entire transaction to abort, not just the statement.
 908                         # https://dev.mysql.com/doc/refman/5.7/en/innodb-error-handling.html
 909                         # https://www.postgresql.org/docs/9.1/static/explicit-locking.html
 910                         if ( $this->wasDeadlock() ) {
 911                                 if ( $this->explicitTrxActive() || $priorWritesPending ) {
 912                                         $tempIgnore = false; // not recoverable
 913                                 }
 914                                 # Update state tracking to reflect transaction loss
 915                                 $this->handleSessionLoss();
 916                         }
 917
 918                         $this->reportQueryError(
 919                                 $this->lastError(), $this->lastErrno(), $sql, $fname, $tempIgnore );
 920                 }
 921
 922                 $res = $this->resultObject( $ret );
 923
 924                 return $res;
 925         }
 926
 927         private function doProfiledQuery( $sql, $commentedSql, $isWrite, $fname ) {
 928                 $isMaster = !is_null( $this->getLBInfo( 'master' ) );
 929                 # generalizeSQL() will probably cut down the query to reasonable
 930                 # logging size most of the time. The substr is really just a sanity check.
 931                 if ( $isMaster ) {
 932                         $queryProf = 'query-m: ' . substr( self::generalizeSQL( $sql ), 0, 255 );
 933                 } else {
 934                         $queryProf = 'query: ' . substr( self::generalizeSQL( $sql ), 0, 255 );
 935                 }
 936
 937                 # Include query transaction state
 938                 $queryProf .= $this->mTrxShortId ? " [TRX#{$this->mTrxShortId}]" : "";
 939
 940                 $startTime = microtime( true );
 941                 if ( $this->profiler ) {
 942                         call_user_func( [ $this->profiler, 'profileIn' ], $queryProf );
 943                 }
 944                 $ret = $this->doQuery( $commentedSql );
 945                 if ( $this->profiler ) {
 946                         call_user_func( [ $this->profiler, 'profileOut' ], $queryProf );
 947                 }
 948                 $queryRuntime = max( microtime( true ) - $startTime, 0.0 );
 949
 950                 unset( $queryProfSection ); // profile out (if set)
 951
 952                 if ( $ret !== false ) {
 953                         $this->lastPing = $startTime;
 954                         if ( $isWrite && $this->mTrxLevel ) {
 955                                 $this->updateTrxWriteQueryTime( $sql, $queryRuntime );
 956                                 $this->mTrxWriteCallers[] = $fname;
 957                         }
 958                 }
 959
 960                 if ( $sql === self::PING_QUERY ) {
 961                         $this->mRTTEstimate = $queryRuntime;
 962                 }
 963
 964                 $this->trxProfiler->recordQueryCompletion(
 965                         $queryProf, $startTime, $isWrite, $this->affectedRows()
 966                 );
 967                 $this->queryLogger->debug( $sql, [
 968                         'method' => $fname,
 969                         'master' => $isMaster,
 970                         'runtime' => $queryRuntime,
 971                 ] );
 972
 973                 return $ret;
 974         }
 975
 976         /**
 977          * Update the estimated run-time of a query, not counting large row lock times
 978          *
 979          * LoadBalancer can be set to rollback transactions that will create huge replication
 980          * lag. It bases this estimate off of pendingWriteQueryDuration(). Certain simple
 981          * queries, like inserting a row can take a long time due to row locking. This method
 982          * uses some simple heuristics to discount those cases.
 983          *
 984          * @param string $sql A SQL write query
 985          * @param float $runtime Total runtime, including RTT
 986          */
 987         private function updateTrxWriteQueryTime( $sql, $runtime ) {
 988                 // Whether this is indicative of replica DB runtime (except for RBR or ws_repl)
 989                 $indicativeOfReplicaRuntime = true;
 990                 if ( $runtime > self::SLOW_WRITE_SEC ) {
 991                         $verb = $this->getQueryVerb( $sql );
 992                         // insert(), upsert(), replace() are fast unless bulky in size or blocked on locks
 993                         if ( $verb === 'INSERT' ) {
 994                                 $indicativeOfReplicaRuntime = $this->affectedRows() > self::SMALL_WRITE_ROWS;
 995                         } elseif ( $verb === 'REPLACE' ) {
 996                                 $indicativeOfReplicaRuntime = $this->affectedRows() > self::SMALL_WRITE_ROWS / 2;
 997                         }
 998                 }
 999
1000                 $this->mTrxWriteDuration += $runtime;
1001                 $this->mTrxWriteQueryCount += 1;
1002                 if ( $indicativeOfReplicaRuntime ) {
1003                         $this->mTrxWriteAdjDuration += $runtime;
1004                         $this->mTrxWriteAdjQueryCount += 1;
1005                 }
1006         }
1007
1008         private function canRecoverFromDisconnect( $sql, $priorWritesPending ) {
1009                 # Transaction dropped; this can mean lost writes, or REPEATABLE-READ snapshots.
1010                 # Dropped connections also mean that named locks are automatically released.
1011                 # Only allow error suppression in autocommit mode or when the lost transaction
1012                 # didn't matter anyway (aside from DBO_TRX snapshot loss).
1013                 if ( $this->mNamedLocksHeld ) {
1014                         return false; // possible critical section violation
1015                 } elseif ( $sql === 'COMMIT' ) {
1016                         return !$priorWritesPending; // nothing written anyway? (T127428)
1017                 } elseif ( $sql === 'ROLLBACK' ) {
1018                         return true; // transaction lost...which is also what was requested :)
1019                 } elseif ( $this->explicitTrxActive() ) {
1020                         return false; // don't drop atomocity
1021                 } elseif ( $priorWritesPending ) {
1022                         return false; // prior writes lost from implicit transaction
1023                 }
1024
1025                 return true;
1026         }
1027
1028         private function handleSessionLoss() {
1029                 $this->mTrxLevel = 0;
1030                 $this->mTrxIdleCallbacks = []; // T67263
1031                 $this->mTrxPreCommitCallbacks = []; // T67263
1032                 $this->mSessionTempTables = [];
1033                 $this->mNamedLocksHeld = [];
1034                 try {
1035                         // Handle callbacks in mTrxEndCallbacks
1036                         $this->runOnTransactionIdleCallbacks( self::TRIGGER_ROLLBACK );
1037                         $this->runTransactionListenerCallbacks( self::TRIGGER_ROLLBACK );
1038                         return null;
1039                 } catch ( Exception $e ) {
1040                         // Already logged; move on...
1041                         return $e;
1042                 }
1043         }
1044
1045         public function reportQueryError( $error, $errno, $sql, $fname, $tempIgnore = false ) {
1046                 if ( $this->ignoreErrors() || $tempIgnore ) {
1047                         $this->queryLogger->debug( "SQL ERROR (ignored): $error\n" );
1048                 } else {
1049                         $sql1line = mb_substr( str_replace( "\n", "\\n", $sql ), 0, 5 * 1024 );
1050                         $this->queryLogger->error(
1051                                 "{fname}\t{db_server}\t{errno}\t{error}\t{sql1line}",
1052                                 $this->getLogContext( [
1053                                         'method' => __METHOD__,
1054                                         'errno' => $errno,
1055                                         'error' => $error,
1056                                         'sql1line' => $sql1line,
1057                                         'fname' => $fname,
1058                                 ] )
1059                         );
1060                         $this->queryLogger->debug( "SQL ERROR: " . $error . "\n" );
1061                         throw new DBQueryError( $this, $error, $errno, $sql, $fname );
1062                 }
1063         }
1064
1065         public function freeResult( $res ) {
1066         }
1067
1068         public function selectField(
1069                 $table, $var, $cond = '', $fname = __METHOD__, $options = []
1070         ) {
1071                 if ( $var === '*' ) { // sanity
1072                         throw new DBUnexpectedError( $this, "Cannot use a * field: got '$var'" );
1073                 }
1074
1075                 if ( !is_array( $options ) ) {
1076                         $options = [ $options ];
1077                 }
1078
1079                 $options['LIMIT'] = 1;
1080
1081                 $res = $this->select( $table, $var, $cond, $fname, $options );
1082                 if ( $res === false || !$this->numRows( $res ) ) {
1083                         return false;
1084                 }
1085
1086                 $row = $this->fetchRow( $res );
1087
1088                 if ( $row !== false ) {
1089                         return reset( $row );
1090                 } else {
1091                         return false;
1092                 }
1093         }
1094
1095         public function selectFieldValues(
1096                 $table, $var, $cond = '', $fname = __METHOD__, $options = [], $join_conds = []
1097         ) {
1098                 if ( $var === '*' ) { // sanity
1099                         throw new DBUnexpectedError( $this, "Cannot use a * field" );
1100                 } elseif ( !is_string( $var ) ) { // sanity
1101                         throw new DBUnexpectedError( $this, "Cannot use an array of fields" );
1102                 }
1103
1104                 if ( !is_array( $options ) ) {
1105                         $options = [ $options ];
1106                 }
1107
1108                 $res = $this->select( $table, $var, $cond, $fname, $options, $join_conds );
1109                 if ( $res === false ) {
1110                         return false;
1111                 }
1112
1113                 $values = [];
1114                 foreach ( $res as $row ) {
1115                         $values[] = $row->$var;
1116                 }
1117
1118                 return $values;
1119         }
1120
1121         /**
1122          * Returns an optional USE INDEX clause to go after the table, and a
1123          * string to go at the end of the query.
1124          *
1125          * @param array $options Associative array of options to be turned into
1126          *   an SQL query, valid keys are listed in the function.
1127          * @return array
1128          * @see Database::select()
1129          */
1130         protected function makeSelectOptions( $options ) {
1131                 $preLimitTail = $postLimitTail = '';
1132                 $startOpts = '';
1133
1134                 $noKeyOptions = [];
1135
1136                 foreach ( $options as $key => $option ) {
1137                         if ( is_numeric( $key ) ) {
1138                                 $noKeyOptions[$option] = true;
1139                         }
1140                 }
1141
1142                 $preLimitTail .= $this->makeGroupByWithHaving( $options );
1143
1144                 $preLimitTail .= $this->makeOrderBy( $options );
1145
1146                 if ( isset( $noKeyOptions['FOR UPDATE'] ) ) {
1147                         $postLimitTail .= ' FOR UPDATE';
1148                 }
1149
1150                 if ( isset( $noKeyOptions['LOCK IN SHARE MODE'] ) ) {
1151                         $postLimitTail .= ' LOCK IN SHARE MODE';
1152                 }
1153
1154                 if ( isset( $noKeyOptions['DISTINCT'] ) || isset( $noKeyOptions['DISTINCTROW'] ) ) {
1155                         $startOpts .= 'DISTINCT';
1156                 }
1157
1158                 # Various MySQL extensions
1159                 if ( isset( $noKeyOptions['STRAIGHT_JOIN'] ) ) {
1160                         $startOpts .= ' /*! STRAIGHT_JOIN */';
1161                 }
1162
1163                 if ( isset( $noKeyOptions['HIGH_PRIORITY'] ) ) {
1164                         $startOpts .= ' HIGH_PRIORITY';
1165                 }
1166
1167                 if ( isset( $noKeyOptions['SQL_BIG_RESULT'] ) ) {
1168                         $startOpts .= ' SQL_BIG_RESULT';
1169                 }
1170
1171                 if ( isset( $noKeyOptions['SQL_BUFFER_RESULT'] ) ) {
1172                         $startOpts .= ' SQL_BUFFER_RESULT';
1173                 }
1174
1175                 if ( isset( $noKeyOptions['SQL_SMALL_RESULT'] ) ) {
1176                         $startOpts .= ' SQL_SMALL_RESULT';
1177                 }
1178
1179                 if ( isset( $noKeyOptions['SQL_CALC_FOUND_ROWS'] ) ) {
1180                         $startOpts .= ' SQL_CALC_FOUND_ROWS';
1181                 }
1182
1183                 if ( isset( $noKeyOptions['SQL_CACHE'] ) ) {
1184                         $startOpts .= ' SQL_CACHE';
1185                 }
1186
1187                 if ( isset( $noKeyOptions['SQL_NO_CACHE'] ) ) {
1188                         $startOpts .= ' SQL_NO_CACHE';
1189                 }
1190
1191                 if ( isset( $options['USE INDEX'] ) && is_string( $options['USE INDEX'] ) ) {
1192                         $useIndex = $this->useIndexClause( $options['USE INDEX'] );
1193                 } else {
1194                         $useIndex = '';
1195                 }
1196                 if ( isset( $options['IGNORE INDEX'] ) && is_string( $options['IGNORE INDEX'] ) ) {
1197                         $ignoreIndex = $this->ignoreIndexClause( $options['IGNORE INDEX'] );
1198                 } else {
1199                         $ignoreIndex = '';
1200                 }
1201
1202                 return [ $startOpts, $useIndex, $preLimitTail, $postLimitTail, $ignoreIndex ];
1203         }
1204
1205         /**
1206          * Returns an optional GROUP BY with an optional HAVING
1207          *
1208          * @param array $options Associative array of options
1209          * @return string
1210          * @see Database::select()
1211          * @since 1.21
1212          */
1213         protected function makeGroupByWithHaving( $options ) {
1214                 $sql = '';
1215                 if ( isset( $options['GROUP BY'] ) ) {
1216                         $gb = is_array( $options['GROUP BY'] )
1217                                 ? implode( ',', $options['GROUP BY'] )
1218                                 : $options['GROUP BY'];
1219                         $sql .= ' GROUP BY ' . $gb;
1220                 }
1221                 if ( isset( $options['HAVING'] ) ) {
1222                         $having = is_array( $options['HAVING'] )
1223                                 ? $this->makeList( $options['HAVING'], self::LIST_AND )
1224                                 : $options['HAVING'];
1225                         $sql .= ' HAVING ' . $having;
1226                 }
1227
1228                 return $sql;
1229         }
1230
1231         /**
1232          * Returns an optional ORDER BY
1233          *
1234          * @param array $options Associative array of options
1235          * @return string
1236          * @see Database::select()
1237          * @since 1.21
1238          */
1239         protected function makeOrderBy( $options ) {
1240                 if ( isset( $options['ORDER BY'] ) ) {
1241                         $ob = is_array( $options['ORDER BY'] )
1242                                 ? implode( ',', $options['ORDER BY'] )
1243                                 : $options['ORDER BY'];
1244
1245                         return ' ORDER BY ' . $ob;
1246                 }
1247
1248                 return '';
1249         }
1250
1251         public function select( $table, $vars, $conds = '', $fname = __METHOD__,
1252                 $options = [], $join_conds = [] ) {
1253                 $sql = $this->selectSQLText( $table, $vars, $conds, $fname, $options, $join_conds );
1254
1255                 return $this->query( $sql, $fname );
1256         }
1257
1258         public function selectSQLText( $table, $vars, $conds = '', $fname = __METHOD__,
1259                 $options = [], $join_conds = []
1260         ) {
1261                 if ( is_array( $vars ) ) {
1262                         $vars = implode( ',', $this->fieldNamesWithAlias( $vars ) );
1263                 }
1264
1265                 $options = (array)$options;
1266                 $useIndexes = ( isset( $options['USE INDEX'] ) && is_array( $options['USE INDEX'] ) )
1267                         ? $options['USE INDEX']
1268                         : [];
1269                 $ignoreIndexes = (
1270                         isset( $options['IGNORE INDEX'] ) &&
1271                         is_array( $options['IGNORE INDEX'] )
1272                 )
1273                         ? $options['IGNORE INDEX']
1274                         : [];
1275
1276                 if ( is_array( $table ) ) {
1277                         $from = ' FROM ' .
1278                                 $this->tableNamesWithIndexClauseOrJOIN(
1279                                         $table, $useIndexes, $ignoreIndexes, $join_conds );
1280                 } elseif ( $table != '' ) {
1281                         if ( $table[0] == ' ' ) {
1282                                 $from = ' FROM ' . $table;
1283                         } else {
1284                                 $from = ' FROM ' .
1285                                         $this->tableNamesWithIndexClauseOrJOIN(
1286                                                 [ $table ], $useIndexes, $ignoreIndexes, [] );
1287                         }
1288                 } else {
1289                         $from = '';
1290                 }
1291
1292                 list( $startOpts, $useIndex, $preLimitTail, $postLimitTail, $ignoreIndex ) =
1293                         $this->makeSelectOptions( $options );
1294
1295                 if ( !empty( $conds ) ) {
1296                         if ( is_array( $conds ) ) {
1297                                 $conds = $this->makeList( $conds, self::LIST_AND );
1298                         }
1299                         $sql = "SELECT $startOpts $vars $from $useIndex $ignoreIndex " .
1300                                 "WHERE $conds $preLimitTail";
1301                 } else {
1302                         $sql = "SELECT $startOpts $vars $from $useIndex $ignoreIndex $preLimitTail";
1303                 }
1304
1305                 if ( isset( $options['LIMIT'] ) ) {
1306                         $sql = $this->limitResult( $sql, $options['LIMIT'],
1307                                 isset( $options['OFFSET'] ) ? $options['OFFSET'] : false );
1308                 }
1309                 $sql = "$sql $postLimitTail";
1310
1311                 if ( isset( $options['EXPLAIN'] ) ) {
1312                         $sql = 'EXPLAIN ' . $sql;
1313                 }
1314
1315                 return $sql;
1316         }
1317
1318         public function selectRow( $table, $vars, $conds, $fname = __METHOD__,
1319                 $options = [], $join_conds = []
1320         ) {
1321                 $options = (array)$options;
1322                 $options['LIMIT'] = 1;
1323                 $res = $this->select( $table, $vars, $conds, $fname, $options, $join_conds );
1324
1325                 if ( $res === false ) {
1326                         return false;
1327                 }
1328
1329                 if ( !$this->numRows( $res ) ) {
1330                         return false;
1331                 }
1332
1333                 $obj = $this->fetchObject( $res );
1334
1335                 return $obj;
1336         }
1337
1338         public function estimateRowCount(
1339                 $table, $vars = '*', $conds = '', $fname = __METHOD__, $options = []
1340         ) {
1341                 $rows = 0;
1342                 $res = $this->select( $table, [ 'rowcount' => 'COUNT(*)' ], $conds, $fname, $options );
1343
1344                 if ( $res ) {
1345                         $row = $this->fetchRow( $res );
1346                         $rows = ( isset( $row['rowcount'] ) ) ? (int)$row['rowcount'] : 0;
1347                 }
1348
1349                 return $rows;
1350         }
1351
1352         public function selectRowCount(
1353                 $tables, $vars = '*', $conds = '', $fname = __METHOD__, $options = [], $join_conds = []
1354         ) {
1355                 $rows = 0;
1356                 $sql = $this->selectSQLText( $tables, '1', $conds, $fname, $options, $join_conds );
1357                 $res = $this->query( "SELECT COUNT(*) AS rowcount FROM ($sql) tmp_count", $fname );
1358
1359                 if ( $res ) {
1360                         $row = $this->fetchRow( $res );
1361                         $rows = ( isset( $row['rowcount'] ) ) ? (int)$row['rowcount'] : 0;
1362                 }
1363
1364                 return $rows;
1365         }
1366
1367         /**
1368          * Removes most variables from an SQL query and replaces them with X or N for numbers.
1369          * It's only slightly flawed. Don't use for anything important.
1370          *
1371          * @param string $sql A SQL Query
1372          *
1373          * @return string
1374          */
1375         protected static function generalizeSQL( $sql ) {
1376                 # This does the same as the regexp below would do, but in such a way
1377                 # as to avoid crashing php on some large strings.
1378                 # $sql = preg_replace( "/'([^\\\\']|\\\\.)*'|\"([^\\\\\"]|\\\\.)*\"/", "'X'", $sql );
1379
1380                 $sql = str_replace( "\\\\", '', $sql );
1381                 $sql = str_replace( "\\'", '', $sql );
1382                 $sql = str_replace( "\\\"", '', $sql );
1383                 $sql = preg_replace( "/'.*'/s", "'X'", $sql );
1384                 $sql = preg_replace( '/".*"/s', "'X'", $sql );
1385
1386                 # All newlines, tabs, etc replaced by single space
1387                 $sql = preg_replace( '/\s+/', ' ', $sql );
1388
1389                 # All numbers => N,
1390                 # except the ones surrounded by characters, e.g. l10n
1391                 $sql = preg_replace( '/-?\d+(,-?\d+)+/s', 'N,...,N', $sql );
1392                 $sql = preg_replace( '/(?<![a-zA-Z])-?\d+(?![a-zA-Z])/s', 'N', $sql );
1393
1394                 return $sql;
1395         }
1396
1397         public function fieldExists( $table, $field, $fname = __METHOD__ ) {
1398                 $info = $this->fieldInfo( $table, $field );
1399
1400                 return (bool)$info;
1401         }
1402
1403         public function indexExists( $table, $index, $fname = __METHOD__ ) {
1404                 if ( !$this->tableExists( $table ) ) {
1405                         return null;
1406                 }
1407
1408                 $info = $this->indexInfo( $table, $index, $fname );
1409                 if ( is_null( $info ) ) {
1410                         return null;
1411                 } else {
1412                         return $info !== false;
1413                 }
1414         }
1415
1416         public function tableExists( $table, $fname = __METHOD__ ) {
1417                 $tableRaw = $this->tableName( $table, 'raw' );
1418                 if ( isset( $this->mSessionTempTables[$tableRaw] ) ) {
1419                         return true; // already known to exist
1420                 }
1421
1422                 $table = $this->tableName( $table );
1423                 $ignoreErrors = true;
1424                 $res = $this->query( "SELECT 1 FROM $table LIMIT 1", $fname, $ignoreErrors );
1425
1426                 return (bool)$res;
1427         }
1428
1429         public function indexUnique( $table, $index ) {
1430                 $indexInfo = $this->indexInfo( $table, $index );
1431
1432                 if ( !$indexInfo ) {
1433                         return null;
1434                 }
1435
1436                 return !$indexInfo[0]->Non_unique;
1437         }
1438
1439         /**
1440          * Helper for Database::insert().
1441          *
1442          * @param array $options
1443          * @return string
1444          */
1445         protected function makeInsertOptions( $options ) {
1446                 return implode( ' ', $options );
1447         }
1448
1449         public function insert( $table, $a, $fname = __METHOD__, $options = [] ) {
1450                 # No rows to insert, easy just return now
1451                 if ( !count( $a ) ) {
1452                         return true;
1453                 }
1454
1455                 $table = $this->tableName( $table );
1456
1457                 if ( !is_array( $options ) ) {
1458                         $options = [ $options ];
1459                 }
1460
1461                 $fh = null;
1462                 if ( isset( $options['fileHandle'] ) ) {
1463                         $fh = $options['fileHandle'];
1464                 }
1465                 $options = $this->makeInsertOptions( $options );
1466
1467                 if ( isset( $a[0] ) && is_array( $a[0] ) ) {
1468                         $multi = true;
1469                         $keys = array_keys( $a[0] );
1470                 } else {
1471                         $multi = false;
1472                         $keys = array_keys( $a );
1473                 }
1474
1475                 $sql = 'INSERT ' . $options .
1476                         " INTO $table (" . implode( ',', $keys ) . ') VALUES ';
1477
1478                 if ( $multi ) {
1479                         $first = true;
1480                         foreach ( $a as $row ) {
1481                                 if ( $first ) {
1482                                         $first = false;
1483                                 } else {
1484                                         $sql .= ',';
1485                                 }
1486                                 $sql .= '(' . $this->makeList( $row ) . ')';
1487                         }
1488                 } else {
1489                         $sql .= '(' . $this->makeList( $a ) . ')';
1490                 }
1491
1492                 if ( $fh !== null && false === fwrite( $fh, $sql ) ) {
1493                         return false;
1494                 } elseif ( $fh !== null ) {
1495                         return true;
1496                 }
1497
1498                 return (bool)$this->query( $sql, $fname );
1499         }
1500
1501         /**
1502          * Make UPDATE options array for Database::makeUpdateOptions
1503          *
1504          * @param array $options
1505          * @return array
1506          */
1507         protected function makeUpdateOptionsArray( $options ) {
1508                 if ( !is_array( $options ) ) {
1509                         $options = [ $options ];
1510                 }
1511
1512                 $opts = [];
1513
1514                 if ( in_array( 'IGNORE', $options ) ) {
1515                         $opts[] = 'IGNORE';
1516                 }
1517
1518                 return $opts;
1519         }
1520
1521         /**
1522          * Make UPDATE options for the Database::update function
1523          *
1524          * @param array $options The options passed to Database::update
1525          * @return string
1526          */
1527         protected function makeUpdateOptions( $options ) {
1528                 $opts = $this->makeUpdateOptionsArray( $options );
1529
1530                 return implode( ' ', $opts );
1531         }
1532
1533         public function update( $table, $values, $conds, $fname = __METHOD__, $options = [] ) {
1534                 $table = $this->tableName( $table );
1535                 $opts = $this->makeUpdateOptions( $options );
1536                 $sql = "UPDATE $opts $table SET " . $this->makeList( $values, self::LIST_SET );
1537
1538                 if ( $conds !== [] && $conds !== '*' ) {
1539                         $sql .= " WHERE " . $this->makeList( $conds, self::LIST_AND );
1540                 }
1541
1542                 return $this->query( $sql, $fname );
1543         }
1544
1545         public function makeList( $a, $mode = self::LIST_COMMA ) {
1546                 if ( !is_array( $a ) ) {
1547                         throw new DBUnexpectedError( $this, __METHOD__ . ' called with incorrect parameters' );
1548                 }
1549
1550                 $first = true;
1551                 $list = '';
1552
1553                 foreach ( $a as $field => $value ) {
1554                         if ( !$first ) {
1555                                 if ( $mode == self::LIST_AND ) {
1556                                         $list .= ' AND ';
1557                                 } elseif ( $mode == self::LIST_OR ) {
1558                                         $list .= ' OR ';
1559                                 } else {
1560                                         $list .= ',';
1561                                 }
1562                         } else {
1563                                 $first = false;
1564                         }
1565
1566                         if ( ( $mode == self::LIST_AND || $mode == self::LIST_OR ) && is_numeric( $field ) ) {
1567                                 $list .= "($value)";
1568                         } elseif ( $mode == self::LIST_SET && is_numeric( $field ) ) {
1569                                 $list .= "$value";
1570                         } elseif (
1571                                 ( $mode == self::LIST_AND || $mode == self::LIST_OR ) && is_array( $value )
1572                         ) {
1573                                 // Remove null from array to be handled separately if found
1574                                 $includeNull = false;
1575                                 foreach ( array_keys( $value, null, true ) as $nullKey ) {
1576                                         $includeNull = true;
1577                                         unset( $value[$nullKey] );
1578                                 }
1579                                 if ( count( $value ) == 0 && !$includeNull ) {
1580                                         throw new InvalidArgumentException(
1581                                                 __METHOD__ . ": empty input for field $field" );
1582                                 } elseif ( count( $value ) == 0 ) {
1583                                         // only check if $field is null
1584                                         $list .= "$field IS NULL";
1585                                 } else {
1586                                         // IN clause contains at least one valid element
1587                                         if ( $includeNull ) {
1588                                                 // Group subconditions to ensure correct precedence
1589                                                 $list .= '(';
1590                                         }
1591                                         if ( count( $value ) == 1 ) {
1592                                                 // Special-case single values, as IN isn't terribly efficient
1593                                                 // Don't necessarily assume the single key is 0; we don't
1594                                                 // enforce linear numeric ordering on other arrays here.
1595                                                 $value = array_values( $value )[0];
1596                                                 $list .= $field . " = " . $this->addQuotes( $value );
1597                                         } else {
1598                                                 $list .= $field . " IN (" . $this->makeList( $value ) . ") ";
1599                                         }
1600                                         // if null present in array, append IS NULL
1601                                         if ( $includeNull ) {
1602                                                 $list .= " OR $field IS NULL)";
1603                                         }
1604                                 }
1605                         } elseif ( $value === null ) {
1606                                 if ( $mode == self::LIST_AND || $mode == self::LIST_OR ) {
1607                                         $list .= "$field IS ";
1608                                 } elseif ( $mode == self::LIST_SET ) {
1609                                         $list .= "$field = ";
1610                                 }
1611                                 $list .= 'NULL';
1612                         } else {
1613                                 if (
1614                                         $mode == self::LIST_AND || $mode == self::LIST_OR || $mode == self::LIST_SET
1615                                 ) {
1616                                         $list .= "$field = ";
1617                                 }
1618                                 $list .= $mode == self::LIST_NAMES ? $value : $this->addQuotes( $value );
1619                         }
1620                 }
1621
1622                 return $list;
1623         }
1624
1625         public function makeWhereFrom2d( $data, $baseKey, $subKey ) {
1626                 $conds = [];
1627
1628                 foreach ( $data as $base => $sub ) {
1629                         if ( count( $sub ) ) {
1630                                 $conds[] = $this->makeList(
1631                                         [ $baseKey => $base, $subKey => array_keys( $sub ) ],
1632                                         self::LIST_AND );
1633                         }
1634                 }
1635
1636                 if ( $conds ) {
1637                         return $this->makeList( $conds, self::LIST_OR );
1638                 } else {
1639                         // Nothing to search for...
1640                         return false;
1641                 }
1642         }
1643
1644         public function aggregateValue( $valuedata, $valuename = 'value' ) {
1645                 return $valuename;
1646         }
1647
1648         public function bitNot( $field ) {
1649                 return "(~$field)";
1650         }
1651
1652         public function bitAnd( $fieldLeft, $fieldRight ) {
1653                 return "($fieldLeft & $fieldRight)";
1654         }
1655
1656         public function bitOr( $fieldLeft, $fieldRight ) {
1657                 return "($fieldLeft | $fieldRight)";
1658         }
1659
1660         public function buildConcat( $stringList ) {
1661                 return 'CONCAT(' . implode( ',', $stringList ) . ')';
1662         }
1663
1664         public function buildGroupConcatField(
1665                 $delim, $table, $field, $conds = '', $join_conds = []
1666         ) {
1667                 $fld = "GROUP_CONCAT($field SEPARATOR " . $this->addQuotes( $delim ) . ')';
1668
1669                 return '(' . $this->selectSQLText( $table, $fld, $conds, null, [], $join_conds ) . ')';
1670         }
1671
1672         public function buildStringCast( $field ) {
1673                 return $field;
1674         }
1675
1676         public function selectDB( $db ) {
1677                 # Stub. Shouldn't cause serious problems if it's not overridden, but
1678                 # if your database engine supports a concept similar to MySQL's
1679                 # databases you may as well.
1680                 $this->mDBname = $db;
1681
1682                 return true;
1683         }
1684
1685         public function getDBname() {
1686                 return $this->mDBname;
1687         }
1688
1689         public function getServer() {
1690                 return $this->mServer;
1691         }
1692
1693         public function tableName( $name, $format = 'quoted' ) {
1694                 # Skip the entire process when we have a string quoted on both ends.
1695                 # Note that we check the end so that we will still quote any use of
1696                 # use of `database`.table. But won't break things if someone wants
1697                 # to query a database table with a dot in the name.
1698                 if ( $this->isQuotedIdentifier( $name ) ) {
1699                         return $name;
1700                 }
1701
1702                 # Lets test for any bits of text that should never show up in a table
1703                 # name. Basically anything like JOIN or ON which are actually part of
1704                 # SQL queries, but may end up inside of the table value to combine
1705                 # sql. Such as how the API is doing.
1706                 # Note that we use a whitespace test rather than a \b test to avoid
1707                 # any remote case where a word like on may be inside of a table name
1708                 # surrounded by symbols which may be considered word breaks.
1709                 if ( preg_match( '/(^|\s)(DISTINCT|JOIN|ON|AS)(\s|$)/i', $name ) !== 0 ) {
1710                         return $name;
1711                 }
1712
1713                 # Split database and table into proper variables.
1714                 # We reverse the explode so that database.table and table both output
1715                 # the correct table.
1716                 $dbDetails = explode( '.', $name, 3 );
1717                 if ( count( $dbDetails ) == 3 ) {
1718                         list( $database, $schema, $table ) = $dbDetails;
1719                         # We don't want any prefix added in this case
1720                         $prefix = '';
1721                 } elseif ( count( $dbDetails ) == 2 ) {
1722                         list( $database, $table ) = $dbDetails;
1723                         # We don't want any prefix added in this case
1724                         $prefix = '';
1725                         # In dbs that support it, $database may actually be the schema
1726                         # but that doesn't affect any of the functionality here
1727                         $schema = '';
1728                 } else {
1729                         list( $table ) = $dbDetails;
1730                         if ( isset( $this->tableAliases[$table] ) ) {
1731                                 $database = $this->tableAliases[$table]['dbname'];
1732                                 $schema = is_string( $this->tableAliases[$table]['schema'] )
1733                                         ? $this->tableAliases[$table]['schema']
1734                                         : $this->mSchema;
1735                                 $prefix = is_string( $this->tableAliases[$table]['prefix'] )
1736                                         ? $this->tableAliases[$table]['prefix']
1737                                         : $this->mTablePrefix;
1738                         } else {
1739                                 $database = '';
1740                                 $schema = $this->mSchema; # Default schema
1741                                 $prefix = $this->mTablePrefix; # Default prefix
1742                         }
1743                 }
1744
1745                 # Quote $table and apply the prefix if not quoted.
1746                 # $tableName might be empty if this is called from Database::replaceVars()
1747                 $tableName = "{$prefix}{$table}";
1748                 if ( $format === 'quoted'
1749                         && !$this->isQuotedIdentifier( $tableName )
1750                         && $tableName !== ''
1751                 ) {
1752                         $tableName = $this->addIdentifierQuotes( $tableName );
1753                 }
1754
1755                 # Quote $schema and $database and merge them with the table name if needed
1756                 $tableName = $this->prependDatabaseOrSchema( $schema, $tableName, $format );
1757                 $tableName = $this->prependDatabaseOrSchema( $database, $tableName, $format );
1758
1759                 return $tableName;
1760         }
1761
1762         /**
1763          * @param string|null $namespace Database or schema
1764          * @param string $relation Name of table, view, sequence, etc...
1765          * @param string $format One of (raw, quoted)
1766          * @return string Relation name with quoted and merged $namespace as needed
1767          */
1768         private function prependDatabaseOrSchema( $namespace, $relation, $format ) {
1769                 if ( strlen( $namespace ) ) {
1770                         if ( $format === 'quoted' && !$this->isQuotedIdentifier( $namespace ) ) {
1771                                 $namespace = $this->addIdentifierQuotes( $namespace );
1772                         }
1773                         $relation = $namespace . '.' . $relation;
1774                 }
1775
1776                 return $relation;
1777         }
1778
1779         public function tableNames() {
1780                 $inArray = func_get_args();
1781                 $retVal = [];
1782
1783                 foreach ( $inArray as $name ) {
1784                         $retVal[$name] = $this->tableName( $name );
1785                 }
1786
1787                 return $retVal;
1788         }
1789
1790         public function tableNamesN() {
1791                 $inArray = func_get_args();
1792                 $retVal = [];
1793
1794                 foreach ( $inArray as $name ) {
1795                         $retVal[] = $this->tableName( $name );
1796                 }
1797
1798                 return $retVal;
1799         }
1800
1801         /**
1802          * Get an aliased table name
1803          * e.g. tableName AS newTableName
1804          *
1805          * @param string $name Table name, see tableName()
1806          * @param string|bool $alias Alias (optional)
1807          * @return string SQL name for aliased table. Will not alias a table to its own name
1808          */
1809         protected function tableNameWithAlias( $name, $alias = false ) {
1810                 if ( !$alias || $alias == $name ) {
1811                         return $this->tableName( $name );
1812                 } else {
1813                         return $this->tableName( $name ) . ' ' . $this->addIdentifierQuotes( $alias );
1814                 }
1815         }
1816
1817         /**
1818          * Gets an array of aliased table names
1819          *
1820          * @param array $tables [ [alias] => table ]
1821          * @return string[] See tableNameWithAlias()
1822          */
1823         protected function tableNamesWithAlias( $tables ) {
1824                 $retval = [];
1825                 foreach ( $tables as $alias => $table ) {
1826                         if ( is_numeric( $alias ) ) {
1827                                 $alias = $table;
1828                         }
1829                         $retval[] = $this->tableNameWithAlias( $table, $alias );
1830                 }
1831
1832                 return $retval;
1833         }
1834
1835         /**
1836          * Get an aliased field name
1837          * e.g. fieldName AS newFieldName
1838          *
1839          * @param string $name Field name
1840          * @param string|bool $alias Alias (optional)
1841          * @return string SQL name for aliased field. Will not alias a field to its own name
1842          */
1843         protected function fieldNameWithAlias( $name, $alias = false ) {
1844                 if ( !$alias || (string)$alias === (string)$name ) {
1845                         return $name;
1846                 } else {
1847                         return $name . ' AS ' . $this->addIdentifierQuotes( $alias ); // PostgreSQL needs AS
1848                 }
1849         }
1850
1851         /**
1852          * Gets an array of aliased field names
1853          *
1854          * @param array $fields [ [alias] => field ]
1855          * @return string[] See fieldNameWithAlias()
1856          */
1857         protected function fieldNamesWithAlias( $fields ) {
1858                 $retval = [];
1859                 foreach ( $fields as $alias => $field ) {
1860                         if ( is_numeric( $alias ) ) {
1861                                 $alias = $field;
1862                         }
1863                         $retval[] = $this->fieldNameWithAlias( $field, $alias );
1864                 }
1865
1866                 return $retval;
1867         }
1868
1869         /**
1870          * Get the aliased table name clause for a FROM clause
1871          * which might have a JOIN and/or USE INDEX or IGNORE INDEX clause
1872          *
1873          * @param array $tables ( [alias] => table )
1874          * @param array $use_index Same as for select()
1875          * @param array $ignore_index Same as for select()
1876          * @param array $join_conds Same as for select()
1877          * @return string
1878          */
1879         protected function tableNamesWithIndexClauseOrJOIN(
1880                 $tables, $use_index = [], $ignore_index = [], $join_conds = []
1881         ) {
1882                 $ret = [];
1883                 $retJOIN = [];
1884                 $use_index = (array)$use_index;
1885                 $ignore_index = (array)$ignore_index;
1886                 $join_conds = (array)$join_conds;
1887
1888                 foreach ( $tables as $alias => $table ) {
1889                         if ( !is_string( $alias ) ) {
1890                                 // No alias? Set it equal to the table name
1891                                 $alias = $table;
1892                         }
1893                         // Is there a JOIN clause for this table?
1894                         if ( isset( $join_conds[$alias] ) ) {
1895                                 list( $joinType, $conds ) = $join_conds[$alias];
1896                                 $tableClause = $joinType;
1897                                 $tableClause .= ' ' . $this->tableNameWithAlias( $table, $alias );
1898                                 if ( isset( $use_index[$alias] ) ) { // has USE INDEX?
1899                                         $use = $this->useIndexClause( implode( ',', (array)$use_index[$alias] ) );
1900                                         if ( $use != '' ) {
1901                                                 $tableClause .= ' ' . $use;
1902                                         }
1903                                 }
1904                                 if ( isset( $ignore_index[$alias] ) ) { // has IGNORE INDEX?
1905                                         $ignore = $this->ignoreIndexClause(
1906                                                 implode( ',', (array)$ignore_index[$alias] ) );
1907                                         if ( $ignore != '' ) {
1908                                                 $tableClause .= ' ' . $ignore;
1909                                         }
1910                                 }
1911                                 $on = $this->makeList( (array)$conds, self::LIST_AND );
1912                                 if ( $on != '' ) {
1913                                         $tableClause .= ' ON (' . $on . ')';
1914                                 }
1915
1916                                 $retJOIN[] = $tableClause;
1917                         } elseif ( isset( $use_index[$alias] ) ) {
1918                                 // Is there an INDEX clause for this table?
1919                                 $tableClause = $this->tableNameWithAlias( $table, $alias );
1920                                 $tableClause .= ' ' . $this->useIndexClause(
1921                                                 implode( ',', (array)$use_index[$alias] )
1922                                         );
1923
1924                                 $ret[] = $tableClause;
1925                         } elseif ( isset( $ignore_index[$alias] ) ) {
1926                                 // Is there an INDEX clause for this table?
1927                                 $tableClause = $this->tableNameWithAlias( $table, $alias );
1928                                 $tableClause .= ' ' . $this->ignoreIndexClause(
1929                                                 implode( ',', (array)$ignore_index[$alias] )
1930                                         );
1931
1932                                 $ret[] = $tableClause;
1933                         } else {
1934                                 $tableClause = $this->tableNameWithAlias( $table, $alias );
1935
1936                                 $ret[] = $tableClause;
1937                         }
1938                 }
1939
1940                 // We can't separate explicit JOIN clauses with ',', use ' ' for those
1941                 $implicitJoins = !empty( $ret ) ? implode( ',', $ret ) : "";
1942                 $explicitJoins = !empty( $retJOIN ) ? implode( ' ', $retJOIN ) : "";
1943
1944                 // Compile our final table clause
1945                 return implode( ' ', [ $implicitJoins, $explicitJoins ] );
1946         }
1947
1948         /**
1949          * Get the name of an index in a given table.
1950          *
1951          * @param string $index
1952          * @return string
1953          */
1954         protected function indexName( $index ) {
1955                 return $index;
1956         }
1957
1958         public function addQuotes( $s ) {
1959                 if ( $s instanceof Blob ) {
1960                         $s = $s->fetch();
1961                 }
1962                 if ( $s === null ) {
1963                         return 'NULL';
1964                 } elseif ( is_bool( $s ) ) {
1965                         return (int)$s;
1966                 } else {
1967                         # This will also quote numeric values. This should be harmless,
1968                         # and protects against weird problems that occur when they really
1969                         # _are_ strings such as article titles and string->number->string
1970                         # conversion is not 1:1.
1971                         return "'" . $this->strencode( $s ) . "'";
1972                 }
1973         }
1974
1975         /**
1976          * Quotes an identifier using `backticks` or "double quotes" depending on the database type.
1977          * MySQL uses `backticks` while basically everything else uses double quotes.
1978          * Since MySQL is the odd one out here the double quotes are our generic
1979          * and we implement backticks in DatabaseMysql.
1980          *
1981          * @param string $s
1982          * @return string
1983          */
1984         public function addIdentifierQuotes( $s ) {
1985                 return '"' . str_replace( '"', '""', $s ) . '"';
1986         }
1987
1988         /**
1989          * Returns if the given identifier looks quoted or not according to
1990          * the database convention for quoting identifiers .
1991          *
1992          * @note Do not use this to determine if untrusted input is safe.
1993          *   A malicious user can trick this function.
1994          * @param string $name
1995          * @return bool
1996          */
1997         public function isQuotedIdentifier( $name ) {
1998                 return $name[0] == '"' && substr( $name, -1, 1 ) == '"';
1999         }
2000
2001         /**
2002          * @param string $s
2003          * @return string
2004          */
2005         protected function escapeLikeInternal( $s ) {
2006                 return addcslashes( $s, '\%_' );
2007         }
2008
2009         public function buildLike() {
2010                 $params = func_get_args();
2011
2012                 if ( count( $params ) > 0 && is_array( $params[0] ) ) {
2013                         $params = $params[0];
2014                 }
2015
2016                 $s = '';
2017
2018                 foreach ( $params as $value ) {
2019                         if ( $value instanceof LikeMatch ) {
2020                                 $s .= $value->toString();
2021                         } else {
2022                                 $s .= $this->escapeLikeInternal( $value );
2023                         }
2024                 }
2025
2026                 return " LIKE {$this->addQuotes( $s )} ";
2027         }
2028
2029         public function anyChar() {
2030                 return new LikeMatch( '_' );
2031         }
2032
2033         public function anyString() {
2034                 return new LikeMatch( '%' );
2035         }
2036
2037         public function nextSequenceValue( $seqName ) {
2038                 return null;
2039         }
2040
2041         /**
2042          * USE INDEX clause. Unlikely to be useful for anything but MySQL. This
2043          * is only needed because a) MySQL must be as efficient as possible due to
2044          * its use on Wikipedia, and b) MySQL 4.0 is kind of dumb sometimes about
2045          * which index to pick. Anyway, other databases might have different
2046          * indexes on a given table. So don't bother overriding this unless you're
2047          * MySQL.
2048          * @param string $index
2049          * @return string
2050          */
2051         public function useIndexClause( $index ) {
2052                 return '';
2053         }
2054
2055         /**
2056          * IGNORE INDEX clause. Unlikely to be useful for anything but MySQL. This
2057          * is only needed because a) MySQL must be as efficient as possible due to
2058          * its use on Wikipedia, and b) MySQL 4.0 is kind of dumb sometimes about
2059          * which index to pick. Anyway, other databases might have different
2060          * indexes on a given table. So don't bother overriding this unless you're
2061          * MySQL.
2062          * @param string $index
2063          * @return string
2064          */
2065         public function ignoreIndexClause( $index ) {
2066                 return '';
2067         }
2068
2069         public function replace( $table, $uniqueIndexes, $rows, $fname = __METHOD__ ) {
2070                 $quotedTable = $this->tableName( $table );
2071
2072                 if ( count( $rows ) == 0 ) {
2073                         return;
2074                 }
2075
2076                 # Single row case
2077                 if ( !is_array( reset( $rows ) ) ) {
2078                         $rows = [ $rows ];
2079                 }
2080
2081                 // @FXIME: this is not atomic, but a trx would break affectedRows()
2082                 foreach ( $rows as $row ) {
2083                         # Delete rows which collide
2084                         if ( $uniqueIndexes ) {
2085                                 $sql = "DELETE FROM $quotedTable WHERE ";
2086                                 $first = true;
2087                                 foreach ( $uniqueIndexes as $index ) {
2088                                         if ( $first ) {
2089                                                 $first = false;
2090                                                 $sql .= '( ';
2091                                         } else {
2092                                                 $sql .= ' ) OR ( ';
2093                                         }
2094                                         if ( is_array( $index ) ) {
2095                                                 $first2 = true;
2096                                                 foreach ( $index as $col ) {
2097                                                         if ( $first2 ) {
2098                                                                 $first2 = false;
2099                                                         } else {
2100                                                                 $sql .= ' AND ';
2101                                                         }
2102                                                         $sql .= $col . '=' . $this->addQuotes( $row[$col] );
2103                                                 }
2104                                         } else {
2105                                                 $sql .= $index . '=' . $this->addQuotes( $row[$index] );
2106                                         }
2107                                 }
2108                                 $sql .= ' )';
2109                                 $this->query( $sql, $fname );
2110                         }
2111
2112                         # Now insert the row
2113                         $this->insert( $table, $row, $fname );
2114                 }
2115         }
2116
2117         /**
2118          * REPLACE query wrapper for MySQL and SQLite, which have a native REPLACE
2119          * statement.
2120          *
2121          * @param string $table Table name
2122          * @param array|string $rows Row(s) to insert
2123          * @param string $fname Caller function name
2124          *
2125          * @return ResultWrapper
2126          */
2127         protected function nativeReplace( $table, $rows, $fname ) {
2128                 $table = $this->tableName( $table );
2129
2130                 # Single row case
2131                 if ( !is_array( reset( $rows ) ) ) {
2132                         $rows = [ $rows ];
2133                 }
2134
2135                 $sql = "REPLACE INTO $table (" . implode( ',', array_keys( $rows[0] ) ) . ') VALUES ';
2136                 $first = true;
2137
2138                 foreach ( $rows as $row ) {
2139                         if ( $first ) {
2140                                 $first = false;
2141                         } else {
2142                                 $sql .= ',';
2143                         }
2144
2145                         $sql .= '(' . $this->makeList( $row ) . ')';
2146                 }
2147
2148                 return $this->query( $sql, $fname );
2149         }
2150
2151         public function upsert( $table, array $rows, array $uniqueIndexes, array $set,
2152                 $fname = __METHOD__
2153         ) {
2154                 if ( !count( $rows ) ) {
2155                         return true; // nothing to do
2156                 }
2157
2158                 if ( !is_array( reset( $rows ) ) ) {
2159                         $rows = [ $rows ];
2160                 }
2161
2162                 if ( count( $uniqueIndexes ) ) {
2163                         $clauses = []; // list WHERE clauses that each identify a single row
2164                         foreach ( $rows as $row ) {
2165                                 foreach ( $uniqueIndexes as $index ) {
2166                                         $index = is_array( $index ) ? $index : [ $index ]; // columns
2167                                         $rowKey = []; // unique key to this row
2168                                         foreach ( $index as $column ) {
2169                                                 $rowKey[$column] = $row[$column];
2170                                         }
2171                                         $clauses[] = $this->makeList( $rowKey, self::LIST_AND );
2172                                 }
2173                         }
2174                         $where = [ $this->makeList( $clauses, self::LIST_OR ) ];
2175                 } else {
2176                         $where = false;
2177                 }
2178
2179                 $useTrx = !$this->mTrxLevel;
2180                 if ( $useTrx ) {
2181                         $this->begin( $fname, self::TRANSACTION_INTERNAL );
2182                 }
2183                 try {
2184                         # Update any existing conflicting row(s)
2185                         if ( $where !== false ) {
2186                                 $ok = $this->update( $table, $set, $where, $fname );
2187                         } else {
2188                                 $ok = true;
2189                         }
2190                         # Now insert any non-conflicting row(s)
2191                         $ok = $this->insert( $table, $rows, $fname, [ 'IGNORE' ] ) && $ok;
2192                 } catch ( Exception $e ) {
2193                         if ( $useTrx ) {
2194                                 $this->rollback( $fname, self::FLUSHING_INTERNAL );
2195                         }
2196                         throw $e;
2197                 }
2198                 if ( $useTrx ) {
2199                         $this->commit( $fname, self::FLUSHING_INTERNAL );
2200                 }
2201
2202                 return $ok;
2203         }
2204
2205         public function deleteJoin( $delTable, $joinTable, $delVar, $joinVar, $conds,
2206                 $fname = __METHOD__
2207         ) {
2208                 if ( !$conds ) {
2209                         throw new DBUnexpectedError( $this, __METHOD__ . ' called with empty $conds' );
2210                 }
2211
2212                 $delTable = $this->tableName( $delTable );
2213                 $joinTable = $this->tableName( $joinTable );
2214                 $sql = "DELETE FROM $delTable WHERE $delVar IN (SELECT $joinVar FROM $joinTable ";
2215                 if ( $conds != '*' ) {
2216                         $sql .= 'WHERE ' . $this->makeList( $conds, self::LIST_AND );
2217                 }
2218                 $sql .= ')';
2219
2220                 $this->query( $sql, $fname );
2221         }
2222
2223         public function textFieldSize( $table, $field ) {
2224                 $table = $this->tableName( $table );
2225                 $sql = "SHOW COLUMNS FROM $table LIKE \"$field\";";
2226                 $res = $this->query( $sql, __METHOD__ );
2227                 $row = $this->fetchObject( $res );
2228
2229                 $m = [];
2230
2231                 if ( preg_match( '/\((.*)\)/', $row->Type, $m ) ) {
2232                         $size = $m[1];
2233                 } else {
2234                         $size = -1;
2235                 }
2236
2237                 return $size;
2238         }
2239
2240         public function delete( $table, $conds, $fname = __METHOD__ ) {
2241                 if ( !$conds ) {
2242                         throw new DBUnexpectedError( $this, __METHOD__ . ' called with no conditions' );
2243                 }
2244
2245                 $table = $this->tableName( $table );
2246                 $sql = "DELETE FROM $table";
2247
2248                 if ( $conds != '*' ) {
2249                         if ( is_array( $conds ) ) {
2250                                 $conds = $this->makeList( $conds, self::LIST_AND );
2251                         }
2252                         $sql .= ' WHERE ' . $conds;
2253                 }
2254
2255                 return $this->query( $sql, $fname );
2256         }
2257
2258         public function insertSelect(
2259                 $destTable, $srcTable, $varMap, $conds,
2260                 $fname = __METHOD__, $insertOptions = [], $selectOptions = []
2261         ) {
2262                 if ( $this->cliMode ) {
2263                         // For massive migrations with downtime, we don't want to select everything
2264                         // into memory and OOM, so do all this native on the server side if possible.
2265                         return $this->nativeInsertSelect(
2266                                 $destTable,
2267                                 $srcTable,
2268                                 $varMap,
2269                                 $conds,
2270                                 $fname,
2271                                 $insertOptions,
2272                                 $selectOptions
2273                         );
2274                 }
2275
2276                 // For web requests, do a locking SELECT and then INSERT. This puts the SELECT burden
2277                 // on only the master (without needing row-based-replication). It also makes it easy to
2278                 // know how big the INSERT is going to be.
2279                 $fields = [];
2280                 foreach ( $varMap as $dstColumn => $sourceColumnOrSql ) {
2281                         $fields[] = $this->fieldNameWithAlias( $sourceColumnOrSql, $dstColumn );
2282                 }
2283                 $selectOptions[] = 'FOR UPDATE';
2284                 $res = $this->select( $srcTable, implode( ',', $fields ), $conds, $fname, $selectOptions );
2285                 if ( !$res ) {
2286                         return false;
2287                 }
2288
2289                 $rows = [];
2290                 foreach ( $res as $row ) {
2291                         $rows[] = (array)$row;
2292                 }
2293
2294                 return $this->insert( $destTable, $rows, $fname, $insertOptions );
2295         }
2296
2297         protected function nativeInsertSelect( $destTable, $srcTable, $varMap, $conds,
2298                 $fname = __METHOD__,
2299                 $insertOptions = [], $selectOptions = []
2300         ) {
2301                 $destTable = $this->tableName( $destTable );
2302
2303                 if ( !is_array( $insertOptions ) ) {
2304                         $insertOptions = [ $insertOptions ];
2305                 }
2306
2307                 $insertOptions = $this->makeInsertOptions( $insertOptions );
2308
2309                 if ( !is_array( $selectOptions ) ) {
2310                         $selectOptions = [ $selectOptions ];
2311                 }
2312
2313                 list( $startOpts, $useIndex, $tailOpts, $ignoreIndex ) = $this->makeSelectOptions(
2314                         $selectOptions );
2315
2316                 if ( is_array( $srcTable ) ) {
2317                         $srcTable = implode( ',', array_map( [ $this, 'tableName' ], $srcTable ) );
2318                 } else {
2319                         $srcTable = $this->tableName( $srcTable );
2320                 }
2321
2322                 $sql = "INSERT $insertOptions" .
2323                         " INTO $destTable (" . implode( ',', array_keys( $varMap ) ) . ')' .
2324                         " SELECT $startOpts " . implode( ',', $varMap ) .
2325                         " FROM $srcTable $useIndex $ignoreIndex ";
2326
2327                 if ( $conds != '*' ) {
2328                         if ( is_array( $conds ) ) {
2329                                 $conds = $this->makeList( $conds, self::LIST_AND );
2330                         }
2331                         $sql .= " WHERE $conds";
2332                 }
2333
2334                 $sql .= " $tailOpts";
2335
2336                 return $this->query( $sql, $fname );
2337         }
2338
2339         /**
2340          * Construct a LIMIT query with optional offset. This is used for query
2341          * pages. The SQL should be adjusted so that only the first $limit rows
2342          * are returned. If $offset is provided as well, then the first $offset
2343          * rows should be discarded, and the next $limit rows should be returned.
2344          * If the result of the query is not ordered, then the rows to be returned
2345          * are theoretically arbitrary.
2346          *
2347          * $sql is expected to be a SELECT, if that makes a difference.
2348          *
2349          * The version provided by default works in MySQL and SQLite. It will very
2350          * likely need to be overridden for most other DBMSes.
2351          *
2352          * @param string $sql SQL query we will append the limit too
2353          * @param int $limit The SQL limit
2354          * @param int|bool $offset The SQL offset (default false)
2355          * @throws DBUnexpectedError
2356          * @return string
2357          */
2358         public function limitResult( $sql, $limit, $offset = false ) {
2359                 if ( !is_numeric( $limit ) ) {
2360                         throw new DBUnexpectedError( $this,
2361                                 "Invalid non-numeric limit passed to limitResult()\n" );
2362                 }
2363
2364                 return "$sql LIMIT "
2365                 . ( ( is_numeric( $offset ) && $offset != 0 ) ? "{$offset}," : "" )
2366                 . "{$limit} ";
2367         }
2368
2369         public function unionSupportsOrderAndLimit() {
2370                 return true; // True for almost every DB supported
2371         }
2372
2373         public function unionQueries( $sqls, $all ) {
2374                 $glue = $all ? ') UNION ALL (' : ') UNION (';
2375
2376                 return '(' . implode( $glue, $sqls ) . ')';
2377         }
2378
2379         public function conditional( $cond, $trueVal, $falseVal ) {
2380                 if ( is_array( $cond ) ) {
2381                         $cond = $this->makeList( $cond, self::LIST_AND );
2382                 }
2383
2384                 return " (CASE WHEN $cond THEN $trueVal ELSE $falseVal END) ";
2385         }
2386
2387         public function strreplace( $orig, $old, $new ) {
2388                 return "REPLACE({$orig}, {$old}, {$new})";
2389         }
2390
2391         public function getServerUptime() {
2392                 return 0;
2393         }
2394
2395         public function wasDeadlock() {
2396                 return false;
2397         }
2398
2399         public function wasLockTimeout() {
2400                 return false;
2401         }
2402
2403         public function wasErrorReissuable() {
2404                 return false;
2405         }
2406
2407         public function wasReadOnlyError() {
2408                 return false;
2409         }
2410
2411         /**
2412          * Do not use this method outside of Database/DBError classes
2413          *
2414          * @param integer|string $errno
2415          * @return bool Whether the given query error was a connection drop
2416          */
2417         public function wasConnectionError( $errno ) {
2418                 return false;
2419         }
2420
2421         public function deadlockLoop() {
2422                 $args = func_get_args();
2423                 $function = array_shift( $args );
2424                 $tries = self::DEADLOCK_TRIES;
2425
2426                 $this->begin( __METHOD__ );
2427
2428                 $retVal = null;
2429                 /** @var Exception $e */
2430                 $e = null;
2431                 do {
2432                         try {
2433                                 $retVal = call_user_func_array( $function, $args );
2434                                 break;
2435                         } catch ( DBQueryError $e ) {
2436                                 if ( $this->wasDeadlock() ) {
2437                                         // Retry after a randomized delay
2438                                         usleep( mt_rand( self::DEADLOCK_DELAY_MIN, self::DEADLOCK_DELAY_MAX ) );
2439                                 } else {
2440                                         // Throw the error back up
2441                                         throw $e;
2442                                 }
2443                         }
2444                 } while ( --$tries > 0 );
2445
2446                 if ( $tries <= 0 ) {
2447                         // Too many deadlocks; give up
2448                         $this->rollback( __METHOD__ );
2449                         throw $e;
2450                 } else {
2451                         $this->commit( __METHOD__ );
2452
2453                         return $retVal;
2454                 }
2455         }
2456
2457         public function masterPosWait( DBMasterPos $pos, $timeout ) {
2458                 # Real waits are implemented in the subclass.
2459                 return 0;
2460         }
2461
2462         public function getReplicaPos() {
2463                 # Stub
2464                 return false;
2465         }
2466
2467         public function getMasterPos() {
2468                 # Stub
2469                 return false;
2470         }
2471
2472         public function serverIsReadOnly() {
2473                 return false;
2474         }
2475
2476         final public function onTransactionResolution( callable $callback, $fname = __METHOD__ ) {
2477                 if ( !$this->mTrxLevel ) {
2478                         throw new DBUnexpectedError( $this, "No transaction is active." );
2479                 }
2480                 $this->mTrxEndCallbacks[] = [ $callback, $fname ];
2481         }
2482
2483         final public function onTransactionIdle( callable $callback, $fname = __METHOD__ ) {
2484                 $this->mTrxIdleCallbacks[] = [ $callback, $fname ];
2485                 if ( !$this->mTrxLevel ) {
2486                         $this->runOnTransactionIdleCallbacks( self::TRIGGER_IDLE );
2487                 }
2488         }
2489
2490         final public function onTransactionPreCommitOrIdle( callable $callback, $fname = __METHOD__ ) {
2491                 if ( $this->mTrxLevel ) {
2492                         $this->mTrxPreCommitCallbacks[] = [ $callback, $fname ];
2493                 } else {
2494                         // If no transaction is active, then make one for this callback
2495                         $this->startAtomic( __METHOD__ );
2496                         try {
2497                                 call_user_func( $callback );
2498                                 $this->endAtomic( __METHOD__ );
2499                         } catch ( Exception $e ) {
2500                                 $this->rollback( __METHOD__, self::FLUSHING_INTERNAL );
2501                                 throw $e;
2502                         }
2503                 }
2504         }
2505
2506         final public function setTransactionListener( $name, callable $callback = null ) {
2507                 if ( $callback ) {
2508                         $this->mTrxRecurringCallbacks[$name] = $callback;
2509                 } else {
2510                         unset( $this->mTrxRecurringCallbacks[$name] );
2511                 }
2512         }
2513
2514         /**
2515          * Whether to disable running of post-COMMIT/ROLLBACK callbacks
2516          *
2517          * This method should not be used outside of Database/LoadBalancer
2518          *
2519          * @param bool $suppress
2520          * @since 1.28
2521          */
2522         final public function setTrxEndCallbackSuppression( $suppress ) {
2523                 $this->mTrxEndCallbacksSuppressed = $suppress;
2524         }
2525
2526         /**
2527          * Actually run and consume any "on transaction idle/resolution" callbacks.
2528          *
2529          * This method should not be used outside of Database/LoadBalancer
2530          *
2531          * @param integer $trigger IDatabase::TRIGGER_* constant
2532          * @since 1.20
2533          * @throws Exception
2534          */
2535         public function runOnTransactionIdleCallbacks( $trigger ) {
2536                 if ( $this->mTrxEndCallbacksSuppressed ) {
2537                         return;
2538                 }
2539
2540                 $autoTrx = $this->getFlag( self::DBO_TRX ); // automatic begin() enabled?
2541                 /** @var Exception $e */
2542                 $e = null; // first exception
2543                 do { // callbacks may add callbacks :)
2544                         $callbacks = array_merge(
2545                                 $this->mTrxIdleCallbacks,
2546                                 $this->mTrxEndCallbacks // include "transaction resolution" callbacks
2547                         );
2548                         $this->mTrxIdleCallbacks = []; // consumed (and recursion guard)
2549                         $this->mTrxEndCallbacks = []; // consumed (recursion guard)
2550                         foreach ( $callbacks as $callback ) {
2551                                 try {
2552                                         list( $phpCallback ) = $callback;
2553                                         $this->clearFlag( self::DBO_TRX ); // make each query its own transaction
2554                                         call_user_func_array( $phpCallback, [ $trigger ] );
2555                                         if ( $autoTrx ) {
2556                                                 $this->setFlag( self::DBO_TRX ); // restore automatic begin()
2557                                         } else {
2558                                                 $this->clearFlag( self::DBO_TRX ); // restore auto-commit
2559                                         }
2560                                 } catch ( Exception $ex ) {
2561                                         call_user_func( $this->errorLogger, $ex );
2562                                         $e = $e ?: $ex;
2563                                         // Some callbacks may use startAtomic/endAtomic, so make sure
2564                                         // their transactions are ended so other callbacks don't fail
2565                                         if ( $this->trxLevel() ) {
2566                                                 $this->rollback( __METHOD__, self::FLUSHING_INTERNAL );
2567                                         }
2568                                 }
2569                         }
2570                 } while ( count( $this->mTrxIdleCallbacks ) );
2571
2572                 if ( $e instanceof Exception ) {
2573                         throw $e; // re-throw any first exception
2574                 }
2575         }
2576
2577         /**
2578          * Actually run and consume any "on transaction pre-commit" callbacks.
2579          *
2580          * This method should not be used outside of Database/LoadBalancer
2581          *
2582          * @since 1.22
2583          * @throws Exception
2584          */
2585         public function runOnTransactionPreCommitCallbacks() {
2586                 $e = null; // first exception
2587                 do { // callbacks may add callbacks :)
2588                         $callbacks = $this->mTrxPreCommitCallbacks;
2589                         $this->mTrxPreCommitCallbacks = []; // consumed (and recursion guard)
2590                         foreach ( $callbacks as $callback ) {
2591                                 try {
2592                                         list( $phpCallback ) = $callback;
2593                                         call_user_func( $phpCallback );
2594                                 } catch ( Exception $ex ) {
2595                                         call_user_func( $this->errorLogger, $ex );
2596                                         $e = $e ?: $ex;
2597                                 }
2598                         }
2599                 } while ( count( $this->mTrxPreCommitCallbacks ) );
2600
2601                 if ( $e instanceof Exception ) {
2602                         throw $e; // re-throw any first exception
2603                 }
2604         }
2605
2606         /**
2607          * Actually run any "transaction listener" callbacks.
2608          *
2609          * This method should not be used outside of Database/LoadBalancer
2610          *
2611          * @param integer $trigger IDatabase::TRIGGER_* constant
2612          * @throws Exception
2613          * @since 1.20
2614          */
2615         public function runTransactionListenerCallbacks( $trigger ) {
2616                 if ( $this->mTrxEndCallbacksSuppressed ) {
2617                         return;
2618                 }
2619
2620                 /** @var Exception $e */
2621                 $e = null; // first exception
2622
2623                 foreach ( $this->mTrxRecurringCallbacks as $phpCallback ) {
2624                         try {
2625                                 $phpCallback( $trigger, $this );
2626                         } catch ( Exception $ex ) {
2627                                 call_user_func( $this->errorLogger, $ex );
2628                                 $e = $e ?: $ex;
2629                         }
2630                 }
2631
2632                 if ( $e instanceof Exception ) {
2633                         throw $e; // re-throw any first exception
2634                 }
2635         }
2636
2637         final public function startAtomic( $fname = __METHOD__ ) {
2638                 if ( !$this->mTrxLevel ) {
2639                         $this->begin( $fname, self::TRANSACTION_INTERNAL );
2640                         // If DBO_TRX is set, a series of startAtomic/endAtomic pairs will result
2641                         // in all changes being in one transaction to keep requests transactional.
2642                         if ( !$this->getFlag( self::DBO_TRX ) ) {
2643                                 $this->mTrxAutomaticAtomic = true;
2644                         }
2645                 }
2646
2647                 $this->mTrxAtomicLevels[] = $fname;
2648         }
2649
2650         final public function endAtomic( $fname = __METHOD__ ) {
2651                 if ( !$this->mTrxLevel ) {
2652                         throw new DBUnexpectedError( $this, "No atomic transaction is open (got $fname)." );
2653                 }
2654                 if ( !$this->mTrxAtomicLevels ||
2655                         array_pop( $this->mTrxAtomicLevels ) !== $fname
2656                 ) {
2657                         throw new DBUnexpectedError( $this, "Invalid atomic section ended (got $fname)." );
2658                 }
2659
2660                 if ( !$this->mTrxAtomicLevels && $this->mTrxAutomaticAtomic ) {
2661                         $this->commit( $fname, self::FLUSHING_INTERNAL );
2662                 }
2663         }
2664
2665         final public function doAtomicSection( $fname, callable $callback ) {
2666                 $this->startAtomic( $fname );
2667                 try {
2668                         $res = call_user_func_array( $callback, [ $this, $fname ] );
2669                 } catch ( Exception $e ) {
2670                         $this->rollback( $fname, self::FLUSHING_INTERNAL );
2671                         throw $e;
2672                 }
2673                 $this->endAtomic( $fname );
2674
2675                 return $res;
2676         }
2677
2678         final public function begin( $fname = __METHOD__, $mode = self::TRANSACTION_EXPLICIT ) {
2679                 // Protect against mismatched atomic section, transaction nesting, and snapshot loss
2680                 if ( $this->mTrxLevel ) {
2681                         if ( $this->mTrxAtomicLevels ) {
2682                                 $levels = implode( ', ', $this->mTrxAtomicLevels );
2683                                 $msg = "$fname: Got explicit BEGIN while atomic section(s) $levels are open.";
2684                                 throw new DBUnexpectedError( $this, $msg );
2685                         } elseif ( !$this->mTrxAutomatic ) {
2686                                 $msg = "$fname: Explicit transaction already active (from {$this->mTrxFname}).";
2687                                 throw new DBUnexpectedError( $this, $msg );
2688                         } else {
2689                                 // @TODO: make this an exception at some point
2690                                 $msg = "$fname: Implicit transaction already active (from {$this->mTrxFname}).";
2691                                 $this->queryLogger->error( $msg );
2692                                 return; // join the main transaction set
2693                         }
2694                 } elseif ( $this->getFlag( self::DBO_TRX ) && $mode !== self::TRANSACTION_INTERNAL ) {
2695                         // @TODO: make this an exception at some point
2696                         $msg = "$fname: Implicit transaction expected (DBO_TRX set).";
2697                         $this->queryLogger->error( $msg );
2698                         return; // let any writes be in the main transaction
2699                 }
2700
2701                 // Avoid fatals if close() was called
2702                 $this->assertOpen();
2703
2704                 $this->doBegin( $fname );
2705                 $this->mTrxTimestamp = microtime( true );
2706                 $this->mTrxFname = $fname;
2707                 $this->mTrxDoneWrites = false;
2708                 $this->mTrxAutomaticAtomic = false;
2709                 $this->mTrxAtomicLevels = [];
2710                 $this->mTrxShortId = sprintf( '%06x', mt_rand( 0, 0xffffff ) );
2711                 $this->mTrxWriteDuration = 0.0;
2712                 $this->mTrxWriteQueryCount = 0;
2713                 $this->mTrxWriteAdjDuration = 0.0;
2714                 $this->mTrxWriteAdjQueryCount = 0;
2715                 $this->mTrxWriteCallers = [];
2716                 // First SELECT after BEGIN will establish the snapshot in REPEATABLE-READ.
2717                 // Get an estimate of the replica DB lag before then, treating estimate staleness
2718                 // as lag itself just to be safe
2719                 $status = $this->getApproximateLagStatus();
2720                 $this->mTrxReplicaLag = $status['lag'] + ( microtime( true ) - $status['since'] );
2721                 // T147697: make explicitTrxActive() return true until begin() finishes. This way, no
2722                 // caller will think its OK to muck around with the transaction just because startAtomic()
2723                 // has not yet completed (e.g. setting mTrxAtomicLevels).
2724                 $this->mTrxAutomatic = ( $mode === self::TRANSACTION_INTERNAL );
2725         }
2726
2727         /**
2728          * Issues the BEGIN command to the database server.
2729          *
2730          * @see Database::begin()
2731          * @param string $fname
2732          */
2733         protected function doBegin( $fname ) {
2734                 $this->query( 'BEGIN', $fname );
2735                 $this->mTrxLevel = 1;
2736         }
2737
2738         final public function commit( $fname = __METHOD__, $flush = '' ) {
2739                 if ( $this->mTrxLevel && $this->mTrxAtomicLevels ) {
2740                         // There are still atomic sections open. This cannot be ignored
2741                         $levels = implode( ', ', $this->mTrxAtomicLevels );
2742                         throw new DBUnexpectedError(
2743                                 $this,
2744                                 "$fname: Got COMMIT while atomic sections $levels are still open."
2745                         );
2746                 }
2747
2748                 if ( $flush === self::FLUSHING_INTERNAL || $flush === self::FLUSHING_ALL_PEERS ) {
2749                         if ( !$this->mTrxLevel ) {
2750                                 return; // nothing to do
2751                         } elseif ( !$this->mTrxAutomatic ) {
2752                                 throw new DBUnexpectedError(
2753                                         $this,
2754                                         "$fname: Flushing an explicit transaction, getting out of sync."
2755                                 );
2756                         }
2757                 } else {
2758                         if ( !$this->mTrxLevel ) {
2759                                 $this->queryLogger->error(
2760                                         "$fname: No transaction to commit, something got out of sync." );
2761                                 return; // nothing to do
2762                         } elseif ( $this->mTrxAutomatic ) {
2763                                 // @TODO: make this an exception at some point
2764                                 $msg = "$fname: Explicit commit of implicit transaction.";
2765                                 $this->queryLogger->error( $msg );
2766                                 return; // wait for the main transaction set commit round
2767                         }
2768                 }
2769
2770                 // Avoid fatals if close() was called
2771                 $this->assertOpen();
2772
2773                 $this->runOnTransactionPreCommitCallbacks();
2774                 $writeTime = $this->pendingWriteQueryDuration( self::ESTIMATE_DB_APPLY );
2775                 $this->doCommit( $fname );
2776                 if ( $this->mTrxDoneWrites ) {
2777                         $this->mLastWriteTime = microtime( true );
2778                         $this->trxProfiler->transactionWritingOut(
2779                                 $this->mServer, $this->mDBname, $this->mTrxShortId, $writeTime );
2780                 }
2781
2782                 $this->runOnTransactionIdleCallbacks( self::TRIGGER_COMMIT );
2783                 $this->runTransactionListenerCallbacks( self::TRIGGER_COMMIT );
2784         }
2785
2786         /**
2787          * Issues the COMMIT command to the database server.
2788          *
2789          * @see Database::commit()
2790          * @param string $fname
2791          */
2792         protected function doCommit( $fname ) {
2793                 if ( $this->mTrxLevel ) {
2794                         $this->query( 'COMMIT', $fname );
2795                         $this->mTrxLevel = 0;
2796                 }
2797         }
2798
2799         final public function rollback( $fname = __METHOD__, $flush = '' ) {
2800                 if ( $flush === self::FLUSHING_INTERNAL || $flush === self::FLUSHING_ALL_PEERS ) {
2801                         if ( !$this->mTrxLevel ) {
2802                                 return; // nothing to do
2803                         }
2804                 } else {
2805                         if ( !$this->mTrxLevel ) {
2806                                 $this->queryLogger->error(
2807                                         "$fname: No transaction to rollback, something got out of sync." );
2808                                 return; // nothing to do
2809                         } elseif ( $this->getFlag( self::DBO_TRX ) ) {
2810                                 throw new DBUnexpectedError(
2811                                         $this,
2812                                         "$fname: Expected mass rollback of all peer databases (DBO_TRX set)."
2813                                 );
2814                         }
2815                 }
2816
2817                 // Avoid fatals if close() was called
2818                 $this->assertOpen();
2819
2820                 $this->doRollback( $fname );
2821                 $this->mTrxAtomicLevels = [];
2822                 if ( $this->mTrxDoneWrites ) {
2823                         $this->trxProfiler->transactionWritingOut(
2824                                 $this->mServer, $this->mDBname, $this->mTrxShortId );
2825                 }
2826
2827                 $this->mTrxIdleCallbacks = []; // clear
2828                 $this->mTrxPreCommitCallbacks = []; // clear
2829                 $this->runOnTransactionIdleCallbacks( self::TRIGGER_ROLLBACK );
2830                 $this->runTransactionListenerCallbacks( self::TRIGGER_ROLLBACK );
2831         }
2832
2833         /**
2834          * Issues the ROLLBACK command to the database server.
2835          *
2836          * @see Database::rollback()
2837          * @param string $fname
2838          */
2839         protected function doRollback( $fname ) {
2840                 if ( $this->mTrxLevel ) {
2841                         # Disconnects cause rollback anyway, so ignore those errors
2842                         $ignoreErrors = true;
2843                         $this->query( 'ROLLBACK', $fname, $ignoreErrors );
2844                         $this->mTrxLevel = 0;
2845                 }
2846         }
2847
2848         public function flushSnapshot( $fname = __METHOD__ ) {
2849                 if ( $this->writesOrCallbacksPending() || $this->explicitTrxActive() ) {
2850                         // This only flushes transactions to clear snapshots, not to write data
2851                         $fnames = implode( ', ', $this->pendingWriteAndCallbackCallers() );
2852                         throw new DBUnexpectedError(
2853                                 $this,
2854                                 "$fname: Cannot flush snapshot because writes are pending ($fnames)."
2855                         );
2856                 }
2857
2858                 $this->commit( $fname, self::FLUSHING_INTERNAL );
2859         }
2860
2861         public function explicitTrxActive() {
2862                 return $this->mTrxLevel && ( $this->mTrxAtomicLevels || !$this->mTrxAutomatic );
2863         }
2864
2865         public function duplicateTableStructure(
2866                 $oldName, $newName, $temporary = false, $fname = __METHOD__
2867         ) {
2868                 throw new RuntimeException( __METHOD__ . ' is not implemented in descendant class' );
2869         }
2870
2871         public function listTables( $prefix = null, $fname = __METHOD__ ) {
2872                 throw new RuntimeException( __METHOD__ . ' is not implemented in descendant class' );
2873         }
2874
2875         public function listViews( $prefix = null, $fname = __METHOD__ ) {
2876                 throw new RuntimeException( __METHOD__ . ' is not implemented in descendant class' );
2877         }
2878
2879         public function timestamp( $ts = 0 ) {
2880                 $t = new ConvertibleTimestamp( $ts );
2881                 // Let errors bubble up to avoid putting garbage in the DB
2882                 return $t->getTimestamp( TS_MW );
2883         }
2884
2885         public function timestampOrNull( $ts = null ) {
2886                 if ( is_null( $ts ) ) {
2887                         return null;
2888                 } else {
2889                         return $this->timestamp( $ts );
2890                 }
2891         }
2892
2893         /**
2894          * Take the result from a query, and wrap it in a ResultWrapper if
2895          * necessary. Boolean values are passed through as is, to indicate success
2896          * of write queries or failure.
2897          *
2898          * Once upon a time, Database::query() returned a bare MySQL result
2899          * resource, and it was necessary to call this function to convert it to
2900          * a wrapper. Nowadays, raw database objects are never exposed to external
2901          * callers, so this is unnecessary in external code.
2902          *
2903          * @param bool|ResultWrapper|resource|object $result
2904          * @return bool|ResultWrapper
2905          */
2906         protected function resultObject( $result ) {
2907                 if ( !$result ) {
2908                         return false;
2909                 } elseif ( $result instanceof ResultWrapper ) {
2910                         return $result;
2911                 } elseif ( $result === true ) {
2912                         // Successful write query
2913                         return $result;
2914                 } else {
2915                         return new ResultWrapper( $this, $result );
2916                 }
2917         }
2918
2919         public function ping( &$rtt = null ) {
2920                 // Avoid hitting the server if it was hit recently
2921                 if ( $this->isOpen() && ( microtime( true ) - $this->lastPing ) < self::PING_TTL ) {
2922                         if ( !func_num_args() || $this->mRTTEstimate > 0 ) {
2923                                 $rtt = $this->mRTTEstimate;
2924                                 return true; // don't care about $rtt
2925                         }
2926                 }
2927
2928                 // This will reconnect if possible or return false if not
2929                 $this->clearFlag( self::DBO_TRX, self::REMEMBER_PRIOR );
2930                 $ok = ( $this->query( self::PING_QUERY, __METHOD__, true ) !== false );
2931                 $this->restoreFlags( self::RESTORE_PRIOR );
2932
2933                 if ( $ok ) {
2934                         $rtt = $this->mRTTEstimate;
2935                 }
2936
2937                 return $ok;
2938         }
2939
2940         /**
2941          * @return bool
2942          */
2943         protected function reconnect() {
2944                 $this->closeConnection();
2945                 $this->mOpened = false;
2946                 $this->mConn = false;
2947                 try {
2948                         $this->open( $this->mServer, $this->mUser, $this->mPassword, $this->mDBname );
2949                         $this->lastPing = microtime( true );
2950                         $ok = true;
2951                 } catch ( DBConnectionError $e ) {
2952                         $ok = false;
2953                 }
2954
2955                 return $ok;
2956         }
2957
2958         public function getSessionLagStatus() {
2959                 return $this->getTransactionLagStatus() ?: $this->getApproximateLagStatus();
2960         }
2961
2962         /**
2963          * Get the replica DB lag when the current transaction started
2964          *
2965          * This is useful when transactions might use snapshot isolation
2966          * (e.g. REPEATABLE-READ in innodb), so the "real" lag of that data
2967          * is this lag plus transaction duration. If they don't, it is still
2968          * safe to be pessimistic. This returns null if there is no transaction.
2969          *
2970          * @return array|null ('lag': seconds or false on error, 'since': UNIX timestamp of BEGIN)
2971          * @since 1.27
2972          */
2973         protected function getTransactionLagStatus() {
2974                 return $this->mTrxLevel
2975                         ? [ 'lag' => $this->mTrxReplicaLag, 'since' => $this->trxTimestamp() ]
2976                         : null;
2977         }
2978
2979         /**
2980          * Get a replica DB lag estimate for this server
2981          *
2982          * @return array ('lag': seconds or false on error, 'since': UNIX timestamp of estimate)
2983          * @since 1.27
2984          */
2985         protected function getApproximateLagStatus() {
2986                 return [
2987                         'lag'   => $this->getLBInfo( 'replica' ) ? $this->getLag() : 0,
2988                         'since' => microtime( true )
2989                 ];
2990         }
2991
2992         /**
2993          * Merge the result of getSessionLagStatus() for several DBs
2994          * using the most pessimistic values to estimate the lag of
2995          * any data derived from them in combination
2996          *
2997          * This is information is useful for caching modules
2998          *
2999          * @see WANObjectCache::set()
3000          * @see WANObjectCache::getWithSetCallback()
3001          *
3002          * @param IDatabase $db1
3003          * @param IDatabase ...
3004          * @return array Map of values:
3005          *   - lag: highest lag of any of the DBs or false on error (e.g. replication stopped)
3006          *   - since: oldest UNIX timestamp of any of the DB lag estimates
3007          *   - pending: whether any of the DBs have uncommitted changes
3008          * @since 1.27
3009          */
3010         public static function getCacheSetOptions( IDatabase $db1 ) {
3011                 $res = [ 'lag' => 0, 'since' => INF, 'pending' => false ];
3012                 foreach ( func_get_args() as $db ) {
3013                         /** @var IDatabase $db */
3014                         $status = $db->getSessionLagStatus();
3015                         if ( $status['lag'] === false ) {
3016                                 $res['lag'] = false;
3017                         } elseif ( $res['lag'] !== false ) {
3018                                 $res['lag'] = max( $res['lag'], $status['lag'] );
3019                         }
3020                         $res['since'] = min( $res['since'], $status['since'] );
3021                         $res['pending'] = $res['pending'] ?: $db->writesPending();
3022                 }
3023
3024                 return $res;
3025         }
3026
3027         public function getLag() {
3028                 return 0;
3029         }
3030
3031         public function maxListLen() {
3032                 return 0;
3033         }
3034
3035         public function encodeBlob( $b ) {
3036                 return $b;
3037         }
3038
3039         public function decodeBlob( $b ) {
3040                 if ( $b instanceof Blob ) {
3041                         $b = $b->fetch();
3042                 }
3043                 return $b;
3044         }
3045
3046         public function setSessionOptions( array $options ) {
3047         }
3048
3049         public function sourceFile(
3050                 $filename,
3051                 callable $lineCallback = null,
3052                 callable $resultCallback = null,
3053                 $fname = false,
3054                 callable $inputCallback = null
3055         ) {
3056                 MediaWiki\suppressWarnings();
3057                 $fp = fopen( $filename, 'r' );
3058                 MediaWiki\restoreWarnings();
3059
3060                 if ( false === $fp ) {
3061                         throw new RuntimeException( "Could not open \"{$filename}\".\n" );
3062                 }
3063
3064                 if ( !$fname ) {
3065                         $fname = __METHOD__ . "( $filename )";
3066                 }
3067
3068                 try {
3069                         $error = $this->sourceStream(
3070                                 $fp, $lineCallback, $resultCallback, $fname, $inputCallback );
3071                 } catch ( Exception $e ) {
3072                         fclose( $fp );
3073                         throw $e;
3074                 }
3075
3076                 fclose( $fp );
3077
3078                 return $error;
3079         }
3080
3081         public function setSchemaVars( $vars ) {
3082                 $this->mSchemaVars = $vars;
3083         }
3084
3085         public function sourceStream(
3086                 $fp,
3087                 callable $lineCallback = null,
3088                 callable $resultCallback = null,
3089                 $fname = __METHOD__,
3090                 callable $inputCallback = null
3091         ) {
3092                 $cmd = '';
3093
3094                 while ( !feof( $fp ) ) {
3095                         if ( $lineCallback ) {
3096                                 call_user_func( $lineCallback );
3097                         }
3098
3099                         $line = trim( fgets( $fp ) );
3100
3101                         if ( $line == '' ) {
3102                                 continue;
3103                         }
3104
3105                         if ( '-' == $line[0] && '-' == $line[1] ) {
3106                                 continue;
3107                         }
3108
3109                         if ( $cmd != '' ) {
3110                                 $cmd .= ' ';
3111                         }
3112
3113                         $done = $this->streamStatementEnd( $cmd, $line );
3114
3115                         $cmd .= "$line\n";
3116
3117                         if ( $done || feof( $fp ) ) {
3118                                 $cmd = $this->replaceVars( $cmd );
3119
3120                                 if ( !$inputCallback || call_user_func( $inputCallback, $cmd ) ) {
3121                                         $res = $this->query( $cmd, $fname );
3122
3123                                         if ( $resultCallback ) {
3124                                                 call_user_func( $resultCallback, $res, $this );
3125                                         }
3126
3127                                         if ( false === $res ) {
3128                                                 $err = $this->lastError();
3129
3130                                                 return "Query \"{$cmd}\" failed with error code \"$err\".\n";
3131                                         }
3132                                 }
3133                                 $cmd = '';
3134                         }
3135                 }
3136
3137                 return true;
3138         }
3139
3140         /**
3141          * Called by sourceStream() to check if we've reached a statement end
3142          *
3143          * @param string &$sql SQL assembled so far
3144          * @param string &$newLine New line about to be added to $sql
3145          * @return bool Whether $newLine contains end of the statement
3146          */
3147         public function streamStatementEnd( &$sql, &$newLine ) {
3148                 if ( $this->delimiter ) {
3149                         $prev = $newLine;
3150                         $newLine = preg_replace(
3151                                 '/' . preg_quote( $this->delimiter, '/' ) . '$/', '', $newLine );
3152                         if ( $newLine != $prev ) {
3153                                 return true;
3154                         }
3155                 }
3156
3157                 return false;
3158         }
3159
3160         /**
3161          * Database independent variable replacement. Replaces a set of variables
3162          * in an SQL statement with their contents as given by $this->getSchemaVars().
3163          *
3164          * Supports '{$var}' `{$var}` and / *$var* / (without the spaces) style variables.
3165          *
3166          * - '{$var}' should be used for text and is passed through the database's
3167          *   addQuotes method.
3168          * - `{$var}` should be used for identifiers (e.g. table and database names).
3169          *   It is passed through the database's addIdentifierQuotes method which
3170          *   can be overridden if the database uses something other than backticks.
3171          * - / *_* / or / *$wgDBprefix* / passes the name that follows through the
3172          *   database's tableName method.
3173          * - / *i* / passes the name that follows through the database's indexName method.
3174          * - In all other cases, / *$var* / is left unencoded. Except for table options,
3175          *   its use should be avoided. In 1.24 and older, string encoding was applied.
3176          *
3177          * @param string $ins SQL statement to replace variables in
3178          * @return string The new SQL statement with variables replaced
3179          */
3180         protected function replaceVars( $ins ) {
3181                 $vars = $this->getSchemaVars();
3182                 return preg_replace_callback(
3183                         '!
3184                                 /\* (\$wgDBprefix|[_i]) \*/ (\w*) | # 1-2. tableName, indexName
3185                                 \'\{\$ (\w+) }\'                  | # 3. addQuotes
3186                                 `\{\$ (\w+) }`                    | # 4. addIdentifierQuotes
3187                                 /\*\$ (\w+) \*/                     # 5. leave unencoded
3188                         !x',
3189                         function ( $m ) use ( $vars ) {
3190                                 // Note: Because of <https://bugs.php.net/bug.php?id=51881>,
3191                                 // check for both nonexistent keys *and* the empty string.
3192                                 if ( isset( $m[1] ) && $m[1] !== '' ) {
3193                                         if ( $m[1] === 'i' ) {
3194                                                 return $this->indexName( $m[2] );
3195                                         } else {
3196                                                 return $this->tableName( $m[2] );
3197                                         }
3198                                 } elseif ( isset( $m[3] ) && $m[3] !== '' && array_key_exists( $m[3], $vars ) ) {
3199                                         return $this->addQuotes( $vars[$m[3]] );
3200                                 } elseif ( isset( $m[4] ) && $m[4] !== '' && array_key_exists( $m[4], $vars ) ) {
3201                                         return $this->addIdentifierQuotes( $vars[$m[4]] );
3202                                 } elseif ( isset( $m[5] ) && $m[5] !== '' && array_key_exists( $m[5], $vars ) ) {
3203                                         return $vars[$m[5]];
3204                                 } else {
3205                                         return $m[0];
3206                                 }
3207                         },
3208                         $ins
3209                 );
3210         }
3211
3212         /**
3213          * Get schema variables. If none have been set via setSchemaVars(), then
3214          * use some defaults from the current object.
3215          *
3216          * @return array
3217          */
3218         protected function getSchemaVars() {
3219                 if ( $this->mSchemaVars ) {
3220                         return $this->mSchemaVars;
3221                 } else {
3222                         return $this->getDefaultSchemaVars();
3223                 }
3224         }
3225
3226         /**
3227          * Get schema variables to use if none have been set via setSchemaVars().
3228          *
3229          * Override this in derived classes to provide variables for tables.sql
3230          * and SQL patch files.
3231          *
3232          * @return array
3233          */
3234         protected function getDefaultSchemaVars() {
3235                 return [];
3236         }
3237
3238         public function lockIsFree( $lockName, $method ) {
3239                 return true;
3240         }
3241
3242         public function lock( $lockName, $method, $timeout = 5 ) {
3243                 $this->mNamedLocksHeld[$lockName] = 1;
3244
3245                 return true;
3246         }
3247
3248         public function unlock( $lockName, $method ) {
3249                 unset( $this->mNamedLocksHeld[$lockName] );
3250
3251                 return true;
3252         }
3253
3254         public function getScopedLockAndFlush( $lockKey, $fname, $timeout ) {
3255                 if ( $this->writesOrCallbacksPending() ) {
3256                         // This only flushes transactions to clear snapshots, not to write data
3257                         $fnames = implode( ', ', $this->pendingWriteAndCallbackCallers() );
3258                         throw new DBUnexpectedError(
3259                                 $this,
3260                                 "$fname: Cannot flush pre-lock snapshot because writes are pending ($fnames)."
3261                         );
3262                 }
3263
3264                 if ( !$this->lock( $lockKey, $fname, $timeout ) ) {
3265                         return null;
3266                 }
3267
3268                 $unlocker = new ScopedCallback( function () use ( $lockKey, $fname ) {
3269                         if ( $this->trxLevel() ) {
3270                                 // There is a good chance an exception was thrown, causing any early return
3271                                 // from the caller. Let any error handler get a chance to issue rollback().
3272                                 // If there isn't one, let the error bubble up and trigger server-side rollback.
3273                                 $this->onTransactionResolution(
3274                                         function () use ( $lockKey, $fname ) {
3275                                                 $this->unlock( $lockKey, $fname );
3276                                         },
3277                                         $fname
3278                                 );
3279                         } else {
3280                                 $this->unlock( $lockKey, $fname );
3281                         }
3282                 } );
3283
3284                 $this->commit( $fname, self::FLUSHING_INTERNAL );
3285
3286                 return $unlocker;
3287         }
3288
3289         public function namedLocksEnqueue() {
3290                 return false;
3291         }
3292
3293         /**
3294          * Lock specific tables
3295          *
3296          * @param array $read Array of tables to lock for read access
3297          * @param array $write Array of tables to lock for write access
3298          * @param string $method Name of caller
3299          * @param bool $lowPriority Whether to indicate writes to be LOW PRIORITY
3300          * @return bool
3301          */
3302         public function lockTables( $read, $write, $method, $lowPriority = true ) {
3303                 return true;
3304         }
3305
3306         /**
3307          * Unlock specific tables
3308          *
3309          * @param string $method The caller
3310          * @return bool
3311          */
3312         public function unlockTables( $method ) {
3313                 return true;
3314         }
3315
3316         /**
3317          * Delete a table
3318          * @param string $tableName
3319          * @param string $fName
3320          * @return bool|ResultWrapper
3321          * @since 1.18
3322          */
3323         public function dropTable( $tableName, $fName = __METHOD__ ) {
3324                 if ( !$this->tableExists( $tableName, $fName ) ) {
3325                         return false;
3326                 }
3327                 $sql = "DROP TABLE " . $this->tableName( $tableName ) . " CASCADE";
3328
3329                 return $this->query( $sql, $fName );
3330         }
3331
3332         public function getInfinity() {
3333                 return 'infinity';
3334         }
3335
3336         public function encodeExpiry( $expiry ) {
3337                 return ( $expiry == '' || $expiry == 'infinity' || $expiry == $this->getInfinity() )
3338                         ? $this->getInfinity()
3339                         : $this->timestamp( $expiry );
3340         }
3341
3342         public function decodeExpiry( $expiry, $format = TS_MW ) {
3343                 if ( $expiry == '' || $expiry == 'infinity' || $expiry == $this->getInfinity() ) {
3344                         return 'infinity';
3345                 }
3346
3347                 return ConvertibleTimestamp::convert( $format, $expiry );
3348         }
3349
3350         public function setBigSelects( $value = true ) {
3351                 // no-op
3352         }
3353
3354         public function isReadOnly() {
3355                 return ( $this->getReadOnlyReason() !== false );
3356         }
3357
3358         /**
3359          * @return string|bool Reason this DB is read-only or false if it is not
3360          */
3361         protected function getReadOnlyReason() {
3362                 $reason = $this->getLBInfo( 'readOnlyReason' );
3363
3364                 return is_string( $reason ) ? $reason : false;
3365         }
3366
3367         public function setTableAliases( array $aliases ) {
3368                 $this->tableAliases = $aliases;
3369         }
3370
3371         /**
3372          * @return bool Whether a DB user is required to access the DB
3373          * @since 1.28
3374          */
3375         protected function requiresDatabaseUser() {
3376                 return true;
3377         }
3378
3379         /**
3380          * Get the underlying binding handle, mConn
3381          *
3382          * Makes sure that mConn is set (disconnects and ping() failure can unset it).
3383          * This catches broken callers than catch and ignore disconnection exceptions.
3384          * Unlike checking isOpen(), this is safe to call inside of open().
3385          *
3386          * @return resource|object
3387          * @throws DBUnexpectedError
3388          * @since 1.26
3389          */
3390         protected function getBindingHandle() {
3391                 if ( !$this->mConn ) {
3392                         throw new DBUnexpectedError(
3393                                 $this,
3394                                 'DB connection was already closed or the connection dropped.'
3395                         );
3396                 }
3397
3398                 return $this->mConn;
3399         }
3400
3401         /**
3402          * @since 1.19
3403          * @return string
3404          */
3405         public function __toString() {
3406                 return (string)$this->mConn;
3407         }
3408
3409         /**
3410          * Make sure that copies do not share the same client binding handle
3411          * @throws DBConnectionError
3412          */
3413         public function __clone() {
3414                 $this->connLogger->warning(
3415                         "Cloning " . static::class . " is not recomended; forking connection:\n" .
3416                         ( new RuntimeException() )->getTraceAsString()
3417                 );
3418
3419                 if ( $this->isOpen() ) {
3420                         // Open a new connection resource without messing with the old one
3421                         $this->mOpened = false;
3422                         $this->mConn = false;
3423                         $this->mTrxEndCallbacks = []; // don't copy
3424                         $this->handleSessionLoss(); // no trx or locks anymore
3425                         $this->open( $this->mServer, $this->mUser, $this->mPassword, $this->mDBname );
3426                         $this->lastPing = microtime( true );
3427                 }
3428         }
3429
3430         /**
3431          * Called by serialize. Throw an exception when DB connection is serialized.
3432          * This causes problems on some database engines because the connection is
3433          * not restored on unserialize.
3434          */
3435         public function __sleep() {
3436                 throw new RuntimeException( 'Database serialization may cause problems, since ' .
3437                         'the connection is not restored on wakeup.' );
3438         }
3439
3440         /**
3441          * Run a few simple sanity checks and close dangling connections
3442          */
3443         public function __destruct() {
3444                 if ( $this->mTrxLevel && $this->mTrxDoneWrites ) {
3445                         trigger_error( "Uncommitted DB writes (transaction from {$this->mTrxFname})." );
3446                 }
3447
3448                 $danglingWriters = $this->pendingWriteAndCallbackCallers();
3449                 if ( $danglingWriters ) {
3450                         $fnames = implode( ', ', $danglingWriters );
3451                         trigger_error( "DB transaction writes or callbacks still pending ($fnames)." );
3452                 }
3453
3454                 if ( $this->mConn ) {
3455                         // Avoid connection leaks for sanity. Normally, resources close at script completion.
3456                         // The connection might already be closed in zend/hhvm by now, so suppress warnings.
3457                         \MediaWiki\suppressWarnings();
3458                         $this->closeConnection();
3459                         \MediaWiki\restoreWarnings();
3460                         $this->mConn = false;
3461                         $this->mOpened = false;
3462                 }
3463         }
3464 }
3465
3466 class_alias( Database::class, 'DatabaseBase' );