includes/libs/rdbms/database/Database.php

   1 <?php
   2 /**
   3  * @defgroup Database Database
   4  *
   5  * This file deals with database interface functions
   6  * and query specifics/optimisations.
   7  *
   8  * This program is free software; you can redistribute it and/or modify
   9  * it under the terms of the GNU General Public License as published by
  10  * the Free Software Foundation; either version 2 of the License, or
  11  * (at your option) any later version.
  12  *
  13  * This program is distributed in the hope that it will be useful,
  14  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  15  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
  16  * GNU General Public License for more details.
  17  *
  18  * You should have received a copy of the GNU General Public License along
  19  * with this program; if not, write to the Free Software Foundation, Inc.,
  20  * 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
  21  * http://www.gnu.org/copyleft/gpl.html
  22  *
  23  * @file
  24  * @ingroup Database
  25  */
  26 use Psr\Log\LoggerAwareInterface;
  27 use Psr\Log\LoggerInterface;
  28
  29 /**
  30  * Database abstraction object
  31  * @ingroup Database
  32  */
  33 abstract class Database implements IDatabase, LoggerAwareInterface {
  34         /** Number of times to re-try an operation in case of deadlock */
  35         const DEADLOCK_TRIES = 4;
  36         /** Minimum time to wait before retry, in microseconds */
  37         const DEADLOCK_DELAY_MIN = 500000;
  38         /** Maximum time to wait before retry */
  39         const DEADLOCK_DELAY_MAX = 1500000;
  40
  41         /** How long before it is worth doing a dummy query to test the connection */
  42         const PING_TTL = 1.0;
  43         const PING_QUERY = 'SELECT 1 AS ping';
  44
  45         const TINY_WRITE_SEC = .010;
  46         const SLOW_WRITE_SEC = .500;
  47         const SMALL_WRITE_ROWS = 100;
  48
  49         /** @var string SQL query */
  50         protected $mLastQuery = '';
  51         /** @var bool */
  52         protected $mDoneWrites = false;
  53         /** @var string|bool */
  54         protected $mPHPError = false;
  55         /** @var string */
  56         protected $mServer;
  57         /** @var string */
  58         protected $mUser;
  59         /** @var string */
  60         protected $mPassword;
  61         /** @var string */
  62         protected $mDBname;
  63         /** @var array[] $aliases Map of (table => (dbname, schema, prefix) map) */
  64         protected $tableAliases = [];
  65         /** @var bool Whether this PHP instance is for a CLI script */
  66         protected $cliMode;
  67         /** @var string Agent name for query profiling */
  68         protected $agent;
  69
  70         /** @var BagOStuff APC cache */
  71         protected $srvCache;
  72         /** @var LoggerInterface */
  73         protected $connLogger;
  74         /** @var LoggerInterface */
  75         protected $queryLogger;
  76         /** @var callback Error logging callback */
  77         protected $errorLogger;
  78
  79         /** @var resource Database connection */
  80         protected $mConn = null;
  81         /** @var bool */
  82         protected $mOpened = false;
  83
  84         /** @var array[] List of (callable, method name) */
  85         protected $mTrxIdleCallbacks = [];
  86         /** @var array[] List of (callable, method name) */
  87         protected $mTrxPreCommitCallbacks = [];
  88         /** @var array[] List of (callable, method name) */
  89         protected $mTrxEndCallbacks = [];
  90         /** @var callable[] Map of (name => callable) */
  91         protected $mTrxRecurringCallbacks = [];
  92         /** @var bool Whether to suppress triggering of transaction end callbacks */
  93         protected $mTrxEndCallbacksSuppressed = false;
  94
  95         /** @var string */
  96         protected $mTablePrefix = '';
  97         /** @var string */
  98         protected $mSchema = '';
  99         /** @var integer */
 100         protected $mFlags;
 101         /** @var array */
 102         protected $mLBInfo = [];
 103         /** @var bool|null */
 104         protected $mDefaultBigSelects = null;
 105         /** @var array|bool */
 106         protected $mSchemaVars = false;
 107         /** @var array */
 108         protected $mSessionVars = [];
 109         /** @var array|null */
 110         protected $preparedArgs;
 111         /** @var string|bool|null Stashed value of html_errors INI setting */
 112         protected $htmlErrors;
 113         /** @var string */
 114         protected $delimiter = ';';
 115         /** @var DatabaseDomain */
 116         protected $currentDomain;
 117
 118         /**
 119          * Either 1 if a transaction is active or 0 otherwise.
 120          * The other Trx fields may not be meaningfull if this is 0.
 121          *
 122          * @var int
 123          */
 124         protected $mTrxLevel = 0;
 125         /**
 126          * Either a short hexidecimal string if a transaction is active or ""
 127          *
 128          * @var string
 129          * @see DatabaseBase::mTrxLevel
 130          */
 131         protected $mTrxShortId = '';
 132         /**
 133          * The UNIX time that the transaction started. Callers can assume that if
 134          * snapshot isolation is used, then the data is *at least* up to date to that
 135          * point (possibly more up-to-date since the first SELECT defines the snapshot).
 136          *
 137          * @var float|null
 138          * @see DatabaseBase::mTrxLevel
 139          */
 140         private $mTrxTimestamp = null;
 141         /** @var float Lag estimate at the time of BEGIN */
 142         private $mTrxReplicaLag = null;
 143         /**
 144          * Remembers the function name given for starting the most recent transaction via begin().
 145          * Used to provide additional context for error reporting.
 146          *
 147          * @var string
 148          * @see DatabaseBase::mTrxLevel
 149          */
 150         private $mTrxFname = null;
 151         /**
 152          * Record if possible write queries were done in the last transaction started
 153          *
 154          * @var bool
 155          * @see DatabaseBase::mTrxLevel
 156          */
 157         private $mTrxDoneWrites = false;
 158         /**
 159          * Record if the current transaction was started implicitly due to DBO_TRX being set.
 160          *
 161          * @var bool
 162          * @see DatabaseBase::mTrxLevel
 163          */
 164         private $mTrxAutomatic = false;
 165         /**
 166          * Array of levels of atomicity within transactions
 167          *
 168          * @var array
 169          */
 170         private $mTrxAtomicLevels = [];
 171         /**
 172          * Record if the current transaction was started implicitly by DatabaseBase::startAtomic
 173          *
 174          * @var bool
 175          */
 176         private $mTrxAutomaticAtomic = false;
 177         /**
 178          * Track the write query callers of the current transaction
 179          *
 180          * @var string[]
 181          */
 182         private $mTrxWriteCallers = [];
 183         /**
 184          * @var float Seconds spent in write queries for the current transaction
 185          */
 186         private $mTrxWriteDuration = 0.0;
 187         /**
 188          * @var integer Number of write queries for the current transaction
 189          */
 190         private $mTrxWriteQueryCount = 0;
 191         /**
 192          * @var float Like mTrxWriteQueryCount but excludes lock-bound, easy to replicate, queries
 193          */
 194         private $mTrxWriteAdjDuration = 0.0;
 195         /**
 196          * @var integer Number of write queries counted in mTrxWriteAdjDuration
 197          */
 198         private $mTrxWriteAdjQueryCount = 0;
 199         /**
 200          * @var float RTT time estimate
 201          */
 202         private $mRTTEstimate = 0.0;
 203
 204         /** @var array Map of (name => 1) for locks obtained via lock() */
 205         private $mNamedLocksHeld = [];
 206
 207         /** @var IDatabase|null Lazy handle to the master DB this server replicates from */
 208         private $lazyMasterHandle;
 209
 210         /**
 211          * @since 1.21
 212          * @var resource File handle for upgrade
 213          */
 214         protected $fileHandle = null;
 215
 216         /**
 217          * @since 1.22
 218          * @var string[] Process cache of VIEWs names in the database
 219          */
 220         protected $allViews = null;
 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 & DBO_DEFAULT ) {
 256                         if ( $this->cliMode ) {
 257                                 $this->mFlags &= ~DBO_TRX;
 258                         } else {
 259                                 $this->mFlags |= 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
 274                 // Set initial dummy domain until open() sets the final DB/prefix
 275                 $this->currentDomain = DatabaseDomain::newUnspecified();
 276
 277                 if ( $user ) {
 278                         $this->open( $server, $user, $password, $dbName );
 279                 } elseif ( $this->requiresDatabaseUser() ) {
 280                         throw new InvalidArgumentException( "No database user provided." );
 281                 }
 282
 283                 // Set the domain object after open() sets the relevant fields
 284                 if ( $this->mDBname != '' ) {
 285                         // Domains with server scope but a table prefix are not used by IDatabase classes
 286                         $this->currentDomain = new DatabaseDomain( $this->mDBname, null, $this->mTablePrefix );
 287                 }
 288         }
 289
 290         /**
 291          * Construct a Database subclass instance given a database type and parameters
 292          *
 293          * This also connects to the database immediately upon object construction
 294          *
 295          * @param string $dbType A possible DB type (sqlite, mysql, postgres)
 296          * @param array $p Parameter map with keys:
 297          *   - host : The hostname of the DB server
 298          *   - user : The name of the database user the client operates under
 299          *   - password : The password for the database user
 300          *   - dbname : The name of the database to use where queries do not specify one.
 301          *      The database must exist or an error might be thrown. Setting this to the empty string
 302          *      will avoid any such errors and make the handle have no implicit database scope. This is
 303          *      useful for queries like SHOW STATUS, CREATE DATABASE, or DROP DATABASE. Note that a
 304          *      "database" in Postgres is rougly equivalent to an entire MySQL server. This the domain
 305          *      in which user names and such are defined, e.g. users are database-specific in Postgres.
 306          *   - schema : The database schema to use (if supported). A "schema" in Postgres is roughly
 307          *      equivalent to a "database" in MySQL. Note that MySQL and SQLite do not use schemas.
 308          *   - tablePrefix : Optional table prefix that is implicitly added on to all table names
 309          *      recognized in queries. This can be used in place of schemas for handle site farms.
 310          *   - flags : Optional bitfield of DBO_* constants that define connection, protocol,
 311          *      buffering, and transaction behavior. It is STRONGLY adviced to leave the DBO_DEFAULT
 312          *      flag in place UNLESS this this database simply acts as a key/value store.
 313          *   - driver: Optional name of a specific DB client driver. For MySQL, there is the old
 314          *      'mysql' driver and the newer 'mysqli' driver.
 315          *   - variables: Optional map of session variables to set after connecting. This can be
 316          *      used to adjust lock timeouts or encoding modes and the like.
 317          *   - connLogger: Optional PSR-3 logger interface instance.
 318          *   - queryLogger: Optional PSR-3 logger interface instance.
 319          *   - profiler: Optional class name or object with profileIn()/profileOut() methods.
 320          *      These will be called in query(), using a simplified version of the SQL that also
 321          *      includes the agent as a SQL comment.
 322          *   - trxProfiler: Optional TransactionProfiler instance.
 323          *   - errorLogger: Optional callback that takes an Exception and logs it.
 324          *   - cliMode: Whether to consider the execution context that of a CLI script.
 325          *   - agent: Optional name used to identify the end-user in query profiling/logging.
 326          *   - srvCache: Optional BagOStuff instance to an APC-style cache.
 327          * @return Database|null If the database driver or extension cannot be found
 328          * @throws InvalidArgumentException If the database driver or extension cannot be found
 329          * @since 1.18
 330          */
 331         final public static function factory( $dbType, $p = [] ) {
 332                 static $canonicalDBTypes = [
 333                         'mysql' => [ 'mysqli', 'mysql' ],
 334                         'postgres' => [],
 335                         'sqlite' => [],
 336                         'oracle' => [],
 337                         'mssql' => [],
 338                 ];
 339
 340                 $driver = false;
 341                 $dbType = strtolower( $dbType );
 342                 if ( isset( $canonicalDBTypes[$dbType] ) && $canonicalDBTypes[$dbType] ) {
 343                         $possibleDrivers = $canonicalDBTypes[$dbType];
 344                         if ( !empty( $p['driver'] ) ) {
 345                                 if ( in_array( $p['driver'], $possibleDrivers ) ) {
 346                                         $driver = $p['driver'];
 347                                 } else {
 348                                         throw new InvalidArgumentException( __METHOD__ .
 349                                                 " type '$dbType' does not support driver '{$p['driver']}'" );
 350                                 }
 351                         } else {
 352                                 foreach ( $possibleDrivers as $posDriver ) {
 353                                         if ( extension_loaded( $posDriver ) ) {
 354                                                 $driver = $posDriver;
 355                                                 break;
 356                                         }
 357                                 }
 358                         }
 359                 } else {
 360                         $driver = $dbType;
 361                 }
 362                 if ( $driver === false ) {
 363                         throw new InvalidArgumentException( __METHOD__ .
 364                                 " no viable database extension found for type '$dbType'" );
 365                 }
 366
 367                 $class = 'Database' . ucfirst( $driver );
 368                 if ( class_exists( $class ) && is_subclass_of( $class, 'IDatabase' ) ) {
 369                         // Resolve some defaults for b/c
 370                         $p['host'] = isset( $p['host'] ) ? $p['host'] : false;
 371                         $p['user'] = isset( $p['user'] ) ? $p['user'] : false;
 372                         $p['password'] = isset( $p['password'] ) ? $p['password'] : false;
 373                         $p['dbname'] = isset( $p['dbname'] ) ? $p['dbname'] : false;
 374                         $p['flags'] = isset( $p['flags'] ) ? $p['flags'] : 0;
 375                         $p['variables'] = isset( $p['variables'] ) ? $p['variables'] : [];
 376                         $p['tablePrefix'] = isset( $p['tablePrefix'] ) ? $p['tablePrefix'] : '';
 377                         $p['schema'] = isset( $p['schema'] ) ? $p['schema'] : '';
 378                         $p['cliMode'] = isset( $p['cliMode'] ) ? $p['cliMode'] : ( PHP_SAPI === 'cli' );
 379                         $p['agent'] = isset( $p['agent'] ) ? $p['agent'] : '';
 380                         if ( !isset( $p['connLogger'] ) ) {
 381                                 $p['connLogger'] = new \Psr\Log\NullLogger();
 382                         }
 383                         if ( !isset( $p['queryLogger'] ) ) {
 384                                 $p['queryLogger'] = new \Psr\Log\NullLogger();
 385                         }
 386                         $p['profiler'] = isset( $p['profiler'] ) ? $p['profiler'] : null;
 387                         if ( !isset( $p['trxProfiler'] ) ) {
 388                                 $p['trxProfiler'] = new TransactionProfiler();
 389                         }
 390                         if ( !isset( $p['errorLogger'] ) ) {
 391                                 $p['errorLogger'] = function ( Exception $e ) {
 392                                         trigger_error( get_class( $e ) . ': ' . $e->getMessage(), E_WARNING );
 393                                 };
 394                         }
 395
 396                         $conn = new $class( $p );
 397                 } else {
 398                         $conn = null;
 399                 }
 400
 401                 return $conn;
 402         }
 403
 404         public function setLogger( LoggerInterface $logger ) {
 405                 $this->queryLogger = $logger;
 406         }
 407
 408         public function getServerInfo() {
 409                 return $this->getServerVersion();
 410         }
 411
 412         public function bufferResults( $buffer = null ) {
 413                 $res = !$this->getFlag( DBO_NOBUFFER );
 414                 if ( $buffer !== null ) {
 415                         $buffer ? $this->clearFlag( DBO_NOBUFFER ) : $this->setFlag( DBO_NOBUFFER );
 416                 }
 417
 418                 return $res;
 419         }
 420
 421         /**
 422          * Turns on (false) or off (true) the automatic generation and sending
 423          * of a "we're sorry, but there has been a database error" page on
 424          * database errors. Default is on (false). When turned off, the
 425          * code should use lastErrno() and lastError() to handle the
 426          * situation as appropriate.
 427          *
 428          * Do not use this function outside of the Database classes.
 429          *
 430          * @param null|bool $ignoreErrors
 431          * @return bool The previous value of the flag.
 432          */
 433         protected function ignoreErrors( $ignoreErrors = null ) {
 434                 $res = $this->getFlag( DBO_IGNORE );
 435                 if ( $ignoreErrors !== null ) {
 436                         $ignoreErrors ? $this->setFlag( DBO_IGNORE ) : $this->clearFlag( DBO_IGNORE );
 437                 }
 438
 439                 return $res;
 440         }
 441
 442         public function trxLevel() {
 443                 return $this->mTrxLevel;
 444         }
 445
 446         public function trxTimestamp() {
 447                 return $this->mTrxLevel ? $this->mTrxTimestamp : null;
 448         }
 449
 450         public function tablePrefix( $prefix = null ) {
 451                 $old = $this->mTablePrefix;
 452                 if ( $prefix !== null ) {
 453                         $this->mTablePrefix = $prefix;
 454                         $this->currentDomain = ( $this->mDBname != '' )
 455                                 ? new DatabaseDomain( $this->mDBname, null, $this->mTablePrefix )
 456                                 : DatabaseDomain::newUnspecified();
 457                 }
 458
 459                 return $old;
 460         }
 461
 462         public function dbSchema( $schema = null ) {
 463                 $old = $this->mSchema;
 464                 if ( $schema !== null ) {
 465                         $this->mSchema = $schema;
 466                 }
 467
 468                 return $old;
 469         }
 470
 471         /**
 472          * Set the filehandle to copy write statements to.
 473          *
 474          * @param resource $fh File handle
 475          */
 476         public function setFileHandle( $fh ) {
 477                 $this->fileHandle = $fh;
 478         }
 479
 480         public function getLBInfo( $name = null ) {
 481                 if ( is_null( $name ) ) {
 482                         return $this->mLBInfo;
 483                 } else {
 484                         if ( array_key_exists( $name, $this->mLBInfo ) ) {
 485                                 return $this->mLBInfo[$name];
 486                         } else {
 487                                 return null;
 488                         }
 489                 }
 490         }
 491
 492         public function setLBInfo( $name, $value = null ) {
 493                 if ( is_null( $value ) ) {
 494                         $this->mLBInfo = $name;
 495                 } else {
 496                         $this->mLBInfo[$name] = $value;
 497                 }
 498         }
 499
 500         public function setLazyMasterHandle( IDatabase $conn ) {
 501                 $this->lazyMasterHandle = $conn;
 502         }
 503
 504         /**
 505          * @return IDatabase|null
 506          * @see setLazyMasterHandle()
 507          * @since 1.27
 508          */
 509         public function getLazyMasterHandle() {
 510                 return $this->lazyMasterHandle;
 511         }
 512
 513         public function implicitGroupby() {
 514                 return true;
 515         }
 516
 517         public function implicitOrderby() {
 518                 return true;
 519         }
 520
 521         public function lastQuery() {
 522                 return $this->mLastQuery;
 523         }
 524
 525         public function doneWrites() {
 526                 return (bool)$this->mDoneWrites;
 527         }
 528
 529         public function lastDoneWrites() {
 530                 return $this->mDoneWrites ?: false;
 531         }
 532
 533         public function writesPending() {
 534                 return $this->mTrxLevel && $this->mTrxDoneWrites;
 535         }
 536
 537         public function writesOrCallbacksPending() {
 538                 return $this->mTrxLevel && (
 539                         $this->mTrxDoneWrites || $this->mTrxIdleCallbacks || $this->mTrxPreCommitCallbacks
 540                 );
 541         }
 542
 543         public function pendingWriteQueryDuration( $type = self::ESTIMATE_TOTAL ) {
 544                 if ( !$this->mTrxLevel ) {
 545                         return false;
 546                 } elseif ( !$this->mTrxDoneWrites ) {
 547                         return 0.0;
 548                 }
 549
 550                 switch ( $type ) {
 551                         case self::ESTIMATE_DB_APPLY:
 552                                 $this->ping( $rtt );
 553                                 $rttAdjTotal = $this->mTrxWriteAdjQueryCount * $rtt;
 554                                 $applyTime = max( $this->mTrxWriteAdjDuration - $rttAdjTotal, 0 );
 555                                 // For omitted queries, make them count as something at least
 556                                 $omitted = $this->mTrxWriteQueryCount - $this->mTrxWriteAdjQueryCount;
 557                                 $applyTime += self::TINY_WRITE_SEC * $omitted;
 558
 559                                 return $applyTime;
 560                         default: // everything
 561                                 return $this->mTrxWriteDuration;
 562                 }
 563         }
 564
 565         public function pendingWriteCallers() {
 566                 return $this->mTrxLevel ? $this->mTrxWriteCallers : [];
 567         }
 568
 569         protected function pendingWriteAndCallbackCallers() {
 570                 if ( !$this->mTrxLevel ) {
 571                         return [];
 572                 }
 573
 574                 $fnames = $this->mTrxWriteCallers;
 575                 foreach ( [
 576                         $this->mTrxIdleCallbacks,
 577                         $this->mTrxPreCommitCallbacks,
 578                         $this->mTrxEndCallbacks
 579                 ] as $callbacks ) {
 580                         foreach ( $callbacks as $callback ) {
 581                                 $fnames[] = $callback[1];
 582                         }
 583                 }
 584
 585                 return $fnames;
 586         }
 587
 588         public function isOpen() {
 589                 return $this->mOpened;
 590         }
 591
 592         public function setFlag( $flag, $remember = self::REMEMBER_NOTHING ) {
 593                 if ( $remember === self::REMEMBER_PRIOR ) {
 594                         array_push( $this->priorFlags, $this->mFlags );
 595                 }
 596                 $this->mFlags |= $flag;
 597         }
 598
 599         public function clearFlag( $flag, $remember = self::REMEMBER_NOTHING ) {
 600                 if ( $remember === self::REMEMBER_PRIOR ) {
 601                         array_push( $this->priorFlags, $this->mFlags );
 602                 }
 603                 $this->mFlags &= ~$flag;
 604         }
 605
 606         public function restoreFlags( $state = self::RESTORE_PRIOR ) {
 607                 if ( !$this->priorFlags ) {
 608                         return;
 609                 }
 610
 611                 if ( $state === self::RESTORE_INITIAL ) {
 612                         $this->mFlags = reset( $this->priorFlags );
 613                         $this->priorFlags = [];
 614                 } else {
 615                         $this->mFlags = array_pop( $this->priorFlags );
 616                 }
 617         }
 618
 619         public function getFlag( $flag ) {
 620                 return !!( $this->mFlags & $flag );
 621         }
 622
 623         public function getProperty( $name ) {
 624                 return $this->$name;
 625         }
 626
 627         public function getDomainID() {
 628                 return $this->currentDomain->getId();
 629         }
 630
 631         final public function getWikiID() {
 632                 return $this->getDomainID();
 633         }
 634
 635         /**
 636          * Get information about an index into an object
 637          * @param string $table Table name
 638          * @param string $index Index name
 639          * @param string $fname Calling function name
 640          * @return mixed Database-specific index description class or false if the index does not exist
 641          */
 642         abstract function indexInfo( $table, $index, $fname = __METHOD__ );
 643
 644         /**
 645          * Wrapper for addslashes()
 646          *
 647          * @param string $s String to be slashed.
 648          * @return string Slashed string.
 649          */
 650         abstract function strencode( $s );
 651
 652         protected function installErrorHandler() {
 653                 $this->mPHPError = false;
 654                 $this->htmlErrors = ini_set( 'html_errors', '0' );
 655                 set_error_handler( [ $this, 'connectionerrorLogger' ] );
 656         }
 657
 658         /**
 659          * @return bool|string
 660          */
 661         protected function restoreErrorHandler() {
 662                 restore_error_handler();
 663                 if ( $this->htmlErrors !== false ) {
 664                         ini_set( 'html_errors', $this->htmlErrors );
 665                 }
 666                 if ( $this->mPHPError ) {
 667                         $error = preg_replace( '!\[<a.*</a>\]!', '', $this->mPHPError );
 668                         $error = preg_replace( '!^.*?:\s?(.*)$!', '$1', $error );
 669
 670                         return $error;
 671                 } else {
 672                         return false;
 673                 }
 674         }
 675
 676         /**
 677          * @param int $errno
 678          * @param string $errstr
 679          */
 680         public function connectionerrorLogger( $errno, $errstr ) {
 681                 $this->mPHPError = $errstr;
 682         }
 683
 684         /**
 685          * Create a log context to pass to PSR-3 logger functions.
 686          *
 687          * @param array $extras Additional data to add to context
 688          * @return array
 689          */
 690         protected function getLogContext( array $extras = [] ) {
 691                 return array_merge(
 692                         [
 693                                 'db_server' => $this->mServer,
 694                                 'db_name' => $this->mDBname,
 695                                 'db_user' => $this->mUser,
 696                         ],
 697                         $extras
 698                 );
 699         }
 700
 701         public function close() {
 702                 if ( $this->mConn ) {
 703                         if ( $this->trxLevel() ) {
 704                                 $this->commit( __METHOD__, self::FLUSHING_INTERNAL );
 705                         }
 706
 707                         $closed = $this->closeConnection();
 708                         $this->mConn = false;
 709                 } elseif ( $this->mTrxIdleCallbacks || $this->mTrxEndCallbacks ) { // sanity
 710                         throw new RuntimeException( "Transaction callbacks still pending." );
 711                 } else {
 712                         $closed = true;
 713                 }
 714                 $this->mOpened = false;
 715
 716                 return $closed;
 717         }
 718
 719         /**
 720          * Make sure isOpen() returns true as a sanity check
 721          *
 722          * @throws DBUnexpectedError
 723          */
 724         protected function assertOpen() {
 725                 if ( !$this->isOpen() ) {
 726                         throw new DBUnexpectedError( $this, "DB connection was already closed." );
 727                 }
 728         }
 729
 730         /**
 731          * Closes underlying database connection
 732          * @since 1.20
 733          * @return bool Whether connection was closed successfully
 734          */
 735         abstract protected function closeConnection();
 736
 737         function reportConnectionError( $error = 'Unknown error' ) {
 738                 $myError = $this->lastError();
 739                 if ( $myError ) {
 740                         $error = $myError;
 741                 }
 742
 743                 # New method
 744                 throw new DBConnectionError( $this, $error );
 745         }
 746
 747         /**
 748          * The DBMS-dependent part of query()
 749          *
 750          * @param string $sql SQL query.
 751          * @return ResultWrapper|bool Result object to feed to fetchObject,
 752          *   fetchRow, ...; or false on failure
 753          */
 754         abstract protected function doQuery( $sql );
 755
 756         /**
 757          * Determine whether a query writes to the DB.
 758          * Should return true if unsure.
 759          *
 760          * @param string $sql
 761          * @return bool
 762          */
 763         protected function isWriteQuery( $sql ) {
 764                 return !preg_match(
 765                         '/^(?:SELECT|BEGIN|ROLLBACK|COMMIT|SET|SHOW|EXPLAIN|\(SELECT)\b/i', $sql );
 766         }
 767
 768         /**
 769          * @param $sql
 770          * @return string|null
 771          */
 772         protected function getQueryVerb( $sql ) {
 773                 return preg_match( '/^\s*([a-z]+)/i', $sql, $m ) ? strtoupper( $m[1] ) : null;
 774         }
 775
 776         /**
 777          * Determine whether a SQL statement is sensitive to isolation level.
 778          * A SQL statement is considered transactable if its result could vary
 779          * depending on the transaction isolation level. Operational commands
 780          * such as 'SET' and 'SHOW' are not considered to be transactable.
 781          *
 782          * @param string $sql
 783          * @return bool
 784          */
 785         protected function isTransactableQuery( $sql ) {
 786                 $verb = $this->getQueryVerb( $sql );
 787                 return !in_array( $verb, [ 'BEGIN', 'COMMIT', 'ROLLBACK', 'SHOW', 'SET' ], true );
 788         }
 789
 790         public function query( $sql, $fname = __METHOD__, $tempIgnore = false ) {
 791                 $priorWritesPending = $this->writesOrCallbacksPending();
 792                 $this->mLastQuery = $sql;
 793
 794                 $isWrite = $this->isWriteQuery( $sql );
 795                 if ( $isWrite ) {
 796                         $reason = $this->getReadOnlyReason();
 797                         if ( $reason !== false ) {
 798                                 throw new DBReadOnlyError( $this, "Database is read-only: $reason" );
 799                         }
 800                         # Set a flag indicating that writes have been done
 801                         $this->mDoneWrites = microtime( true );
 802                 }
 803
 804                 // Add trace comment to the begin of the sql string, right after the operator.
 805                 // Or, for one-word queries (like "BEGIN" or COMMIT") add it to the end (bug 42598)
 806                 $commentedSql = preg_replace( '/\s|$/', " /* $fname {$this->agent} */ ", $sql, 1 );
 807
 808                 # Start implicit transactions that wrap the request if DBO_TRX is enabled
 809                 if ( !$this->mTrxLevel && $this->getFlag( DBO_TRX )
 810                         && $this->isTransactableQuery( $sql )
 811                 ) {
 812                         $this->begin( __METHOD__ . " ($fname)", self::TRANSACTION_INTERNAL );
 813                         $this->mTrxAutomatic = true;
 814                 }
 815
 816                 # Keep track of whether the transaction has write queries pending
 817                 if ( $this->mTrxLevel && !$this->mTrxDoneWrites && $isWrite ) {
 818                         $this->mTrxDoneWrites = true;
 819                         $this->trxProfiler->transactionWritingIn(
 820                                 $this->mServer, $this->mDBname, $this->mTrxShortId );
 821                 }
 822
 823                 if ( $this->getFlag( DBO_DEBUG ) ) {
 824                         $this->queryLogger->debug( "{$this->mDBname} {$commentedSql}" );
 825                 }
 826
 827                 # Avoid fatals if close() was called
 828                 $this->assertOpen();
 829
 830                 # Send the query to the server
 831                 $ret = $this->doProfiledQuery( $sql, $commentedSql, $isWrite, $fname );
 832
 833                 # Try reconnecting if the connection was lost
 834                 if ( false === $ret && $this->wasErrorReissuable() ) {
 835                         $recoverable = $this->canRecoverFromDisconnect( $sql, $priorWritesPending );
 836                         # Stash the last error values before anything might clear them
 837                         $lastError = $this->lastError();
 838                         $lastErrno = $this->lastErrno();
 839                         # Update state tracking to reflect transaction loss due to disconnection
 840                         $this->handleTransactionLoss();
 841                         if ( $this->reconnect() ) {
 842                                 $msg = __METHOD__ . ": lost connection to {$this->getServer()}; reconnected";
 843                                 $this->connLogger->warning( $msg );
 844                                 $this->queryLogger->warning(
 845                                         "$msg:\n" . ( new RuntimeException() )->getTraceAsString() );
 846
 847                                 if ( !$recoverable ) {
 848                                         # Callers may catch the exception and continue to use the DB
 849                                         $this->reportQueryError( $lastError, $lastErrno, $sql, $fname );
 850                                 } else {
 851                                         # Should be safe to silently retry the query
 852                                         $ret = $this->doProfiledQuery( $sql, $commentedSql, $isWrite, $fname );
 853                                 }
 854                         } else {
 855                                 $msg = __METHOD__ . ": lost connection to {$this->getServer()} permanently";
 856                                 $this->connLogger->error( $msg );
 857                         }
 858                 }
 859
 860                 if ( false === $ret ) {
 861                         # Deadlocks cause the entire transaction to abort, not just the statement.
 862                         # http://dev.mysql.com/doc/refman/5.7/en/innodb-error-handling.html
 863                         # https://www.postgresql.org/docs/9.1/static/explicit-locking.html
 864                         if ( $this->wasDeadlock() ) {
 865                                 if ( $this->explicitTrxActive() || $priorWritesPending ) {
 866                                         $tempIgnore = false; // not recoverable
 867                                 }
 868                                 # Update state tracking to reflect transaction loss
 869                                 $this->handleTransactionLoss();
 870                         }
 871
 872                         $this->reportQueryError(
 873                                 $this->lastError(), $this->lastErrno(), $sql, $fname, $tempIgnore );
 874                 }
 875
 876                 $res = $this->resultObject( $ret );
 877
 878                 return $res;
 879         }
 880
 881         private function doProfiledQuery( $sql, $commentedSql, $isWrite, $fname ) {
 882                 $isMaster = !is_null( $this->getLBInfo( 'master' ) );
 883                 # generalizeSQL() will probably cut down the query to reasonable
 884                 # logging size most of the time. The substr is really just a sanity check.
 885                 if ( $isMaster ) {
 886                         $queryProf = 'query-m: ' . substr( self::generalizeSQL( $sql ), 0, 255 );
 887                 } else {
 888                         $queryProf = 'query: ' . substr( self::generalizeSQL( $sql ), 0, 255 );
 889                 }
 890
 891                 # Include query transaction state
 892                 $queryProf .= $this->mTrxShortId ? " [TRX#{$this->mTrxShortId}]" : "";
 893
 894                 $startTime = microtime( true );
 895                 if ( $this->profiler ) {
 896                         call_user_func( [ $this->profiler, 'profileIn' ], $queryProf );
 897                 }
 898                 $ret = $this->doQuery( $commentedSql );
 899                 if ( $this->profiler ) {
 900                         call_user_func( [ $this->profiler, 'profileOut' ], $queryProf );
 901                 }
 902                 $queryRuntime = max( microtime( true ) - $startTime, 0.0 );
 903
 904                 unset( $queryProfSection ); // profile out (if set)
 905
 906                 if ( $ret !== false ) {
 907                         $this->lastPing = $startTime;
 908                         if ( $isWrite && $this->mTrxLevel ) {
 909                                 $this->updateTrxWriteQueryTime( $sql, $queryRuntime );
 910                                 $this->mTrxWriteCallers[] = $fname;
 911                         }
 912                 }
 913
 914                 if ( $sql === self::PING_QUERY ) {
 915                         $this->mRTTEstimate = $queryRuntime;
 916                 }
 917
 918                 $this->trxProfiler->recordQueryCompletion(
 919                         $queryProf, $startTime, $isWrite, $this->affectedRows()
 920                 );
 921                 $this->queryLogger->debug( $sql, [
 922                         'method' => $fname,
 923                         'master' => $isMaster,
 924                         'runtime' => $queryRuntime,
 925                 ] );
 926
 927                 return $ret;
 928         }
 929
 930         /**
 931          * Update the estimated run-time of a query, not counting large row lock times
 932          *
 933          * LoadBalancer can be set to rollback transactions that will create huge replication
 934          * lag. It bases this estimate off of pendingWriteQueryDuration(). Certain simple
 935          * queries, like inserting a row can take a long time due to row locking. This method
 936          * uses some simple heuristics to discount those cases.
 937          *
 938          * @param string $sql A SQL write query
 939          * @param float $runtime Total runtime, including RTT
 940          */
 941         private function updateTrxWriteQueryTime( $sql, $runtime ) {
 942                 // Whether this is indicative of replica DB runtime (except for RBR or ws_repl)
 943                 $indicativeOfReplicaRuntime = true;
 944                 if ( $runtime > self::SLOW_WRITE_SEC ) {
 945                         $verb = $this->getQueryVerb( $sql );
 946                         // insert(), upsert(), replace() are fast unless bulky in size or blocked on locks
 947                         if ( $verb === 'INSERT' ) {
 948                                 $indicativeOfReplicaRuntime = $this->affectedRows() > self::SMALL_WRITE_ROWS;
 949                         } elseif ( $verb === 'REPLACE' ) {
 950                                 $indicativeOfReplicaRuntime = $this->affectedRows() > self::SMALL_WRITE_ROWS / 2;
 951                         }
 952                 }
 953
 954                 $this->mTrxWriteDuration += $runtime;
 955                 $this->mTrxWriteQueryCount += 1;
 956                 if ( $indicativeOfReplicaRuntime ) {
 957                         $this->mTrxWriteAdjDuration += $runtime;
 958                         $this->mTrxWriteAdjQueryCount += 1;
 959                 }
 960         }
 961
 962         private function canRecoverFromDisconnect( $sql, $priorWritesPending ) {
 963                 # Transaction dropped; this can mean lost writes, or REPEATABLE-READ snapshots.
 964                 # Dropped connections also mean that named locks are automatically released.
 965                 # Only allow error suppression in autocommit mode or when the lost transaction
 966                 # didn't matter anyway (aside from DBO_TRX snapshot loss).
 967                 if ( $this->mNamedLocksHeld ) {
 968                         return false; // possible critical section violation
 969                 } elseif ( $sql === 'COMMIT' ) {
 970                         return !$priorWritesPending; // nothing written anyway? (T127428)
 971                 } elseif ( $sql === 'ROLLBACK' ) {
 972                         return true; // transaction lost...which is also what was requested :)
 973                 } elseif ( $this->explicitTrxActive() ) {
 974                         return false; // don't drop atomocity
 975                 } elseif ( $priorWritesPending ) {
 976                         return false; // prior writes lost from implicit transaction
 977                 }
 978
 979                 return true;
 980         }
 981
 982         private function handleTransactionLoss() {
 983                 $this->mTrxLevel = 0;
 984                 $this->mTrxIdleCallbacks = []; // bug 65263
 985                 $this->mTrxPreCommitCallbacks = []; // bug 65263
 986                 try {
 987                         // Handle callbacks in mTrxEndCallbacks
 988                         $this->runOnTransactionIdleCallbacks( self::TRIGGER_ROLLBACK );
 989                         $this->runTransactionListenerCallbacks( self::TRIGGER_ROLLBACK );
 990                         return null;
 991                 } catch ( Exception $e ) {
 992                         // Already logged; move on...
 993                         return $e;
 994                 }
 995         }
 996
 997         public function reportQueryError( $error, $errno, $sql, $fname, $tempIgnore = false ) {
 998                 if ( $this->ignoreErrors() || $tempIgnore ) {
 999                         $this->queryLogger->debug( "SQL ERROR (ignored): $error\n" );
1000                 } else {
1001                         $sql1line = mb_substr( str_replace( "\n", "\\n", $sql ), 0, 5 * 1024 );
1002                         $this->queryLogger->error(
1003                                 "{fname}\t{db_server}\t{errno}\t{error}\t{sql1line}",
1004                                 $this->getLogContext( [
1005                                         'method' => __METHOD__,
1006                                         'errno' => $errno,
1007                                         'error' => $error,
1008                                         'sql1line' => $sql1line,
1009                                         'fname' => $fname,
1010                                 ] )
1011                         );
1012                         $this->queryLogger->debug( "SQL ERROR: " . $error . "\n" );
1013                         throw new DBQueryError( $this, $error, $errno, $sql, $fname );
1014                 }
1015         }
1016
1017         public function freeResult( $res ) {
1018         }
1019
1020         public function selectField(
1021                 $table, $var, $cond = '', $fname = __METHOD__, $options = []
1022         ) {
1023                 if ( $var === '*' ) { // sanity
1024                         throw new DBUnexpectedError( $this, "Cannot use a * field: got '$var'" );
1025                 }
1026
1027                 if ( !is_array( $options ) ) {
1028                         $options = [ $options ];
1029                 }
1030
1031                 $options['LIMIT'] = 1;
1032
1033                 $res = $this->select( $table, $var, $cond, $fname, $options );
1034                 if ( $res === false || !$this->numRows( $res ) ) {
1035                         return false;
1036                 }
1037
1038                 $row = $this->fetchRow( $res );
1039
1040                 if ( $row !== false ) {
1041                         return reset( $row );
1042                 } else {
1043                         return false;
1044                 }
1045         }
1046
1047         public function selectFieldValues(
1048                 $table, $var, $cond = '', $fname = __METHOD__, $options = [], $join_conds = []
1049         ) {
1050                 if ( $var === '*' ) { // sanity
1051                         throw new DBUnexpectedError( $this, "Cannot use a * field" );
1052                 } elseif ( !is_string( $var ) ) { // sanity
1053                         throw new DBUnexpectedError( $this, "Cannot use an array of fields" );
1054                 }
1055
1056                 if ( !is_array( $options ) ) {
1057                         $options = [ $options ];
1058                 }
1059
1060                 $res = $this->select( $table, $var, $cond, $fname, $options, $join_conds );
1061                 if ( $res === false ) {
1062                         return false;
1063                 }
1064
1065                 $values = [];
1066                 foreach ( $res as $row ) {
1067                         $values[] = $row->$var;
1068                 }
1069
1070                 return $values;
1071         }
1072
1073         /**
1074          * Returns an optional USE INDEX clause to go after the table, and a
1075          * string to go at the end of the query.
1076          *
1077          * @param array $options Associative array of options to be turned into
1078          *   an SQL query, valid keys are listed in the function.
1079          * @return array
1080          * @see DatabaseBase::select()
1081          */
1082         public function makeSelectOptions( $options ) {
1083                 $preLimitTail = $postLimitTail = '';
1084                 $startOpts = '';
1085
1086                 $noKeyOptions = [];
1087
1088                 foreach ( $options as $key => $option ) {
1089                         if ( is_numeric( $key ) ) {
1090                                 $noKeyOptions[$option] = true;
1091                         }
1092                 }
1093
1094                 $preLimitTail .= $this->makeGroupByWithHaving( $options );
1095
1096                 $preLimitTail .= $this->makeOrderBy( $options );
1097
1098                 // if (isset($options['LIMIT'])) {
1099                 //      $tailOpts .= $this->limitResult('', $options['LIMIT'],
1100                 //              isset($options['OFFSET']) ? $options['OFFSET']
1101                 //              : false);
1102                 // }
1103
1104                 if ( isset( $noKeyOptions['FOR UPDATE'] ) ) {
1105                         $postLimitTail .= ' FOR UPDATE';
1106                 }
1107
1108                 if ( isset( $noKeyOptions['LOCK IN SHARE MODE'] ) ) {
1109                         $postLimitTail .= ' LOCK IN SHARE MODE';
1110                 }
1111
1112                 if ( isset( $noKeyOptions['DISTINCT'] ) || isset( $noKeyOptions['DISTINCTROW'] ) ) {
1113                         $startOpts .= 'DISTINCT';
1114                 }
1115
1116                 # Various MySQL extensions
1117                 if ( isset( $noKeyOptions['STRAIGHT_JOIN'] ) ) {
1118                         $startOpts .= ' /*! STRAIGHT_JOIN */';
1119                 }
1120
1121                 if ( isset( $noKeyOptions['HIGH_PRIORITY'] ) ) {
1122                         $startOpts .= ' HIGH_PRIORITY';
1123                 }
1124
1125                 if ( isset( $noKeyOptions['SQL_BIG_RESULT'] ) ) {
1126                         $startOpts .= ' SQL_BIG_RESULT';
1127                 }
1128
1129                 if ( isset( $noKeyOptions['SQL_BUFFER_RESULT'] ) ) {
1130                         $startOpts .= ' SQL_BUFFER_RESULT';
1131                 }
1132
1133                 if ( isset( $noKeyOptions['SQL_SMALL_RESULT'] ) ) {
1134                         $startOpts .= ' SQL_SMALL_RESULT';
1135                 }
1136
1137                 if ( isset( $noKeyOptions['SQL_CALC_FOUND_ROWS'] ) ) {
1138                         $startOpts .= ' SQL_CALC_FOUND_ROWS';
1139                 }
1140
1141                 if ( isset( $noKeyOptions['SQL_CACHE'] ) ) {
1142                         $startOpts .= ' SQL_CACHE';
1143                 }
1144
1145                 if ( isset( $noKeyOptions['SQL_NO_CACHE'] ) ) {
1146                         $startOpts .= ' SQL_NO_CACHE';
1147                 }
1148
1149                 if ( isset( $options['USE INDEX'] ) && is_string( $options['USE INDEX'] ) ) {
1150                         $useIndex = $this->useIndexClause( $options['USE INDEX'] );
1151                 } else {
1152                         $useIndex = '';
1153                 }
1154                 if ( isset( $options['IGNORE INDEX'] ) && is_string( $options['IGNORE INDEX'] ) ) {
1155                         $ignoreIndex = $this->ignoreIndexClause( $options['IGNORE INDEX'] );
1156                 } else {
1157                         $ignoreIndex = '';
1158                 }
1159
1160                 return [ $startOpts, $useIndex, $preLimitTail, $postLimitTail, $ignoreIndex ];
1161         }
1162
1163         /**
1164          * Returns an optional GROUP BY with an optional HAVING
1165          *
1166          * @param array $options Associative array of options
1167          * @return string
1168          * @see DatabaseBase::select()
1169          * @since 1.21
1170          */
1171         public function makeGroupByWithHaving( $options ) {
1172                 $sql = '';
1173                 if ( isset( $options['GROUP BY'] ) ) {
1174                         $gb = is_array( $options['GROUP BY'] )
1175                                 ? implode( ',', $options['GROUP BY'] )
1176                                 : $options['GROUP BY'];
1177                         $sql .= ' GROUP BY ' . $gb;
1178                 }
1179                 if ( isset( $options['HAVING'] ) ) {
1180                         $having = is_array( $options['HAVING'] )
1181                                 ? $this->makeList( $options['HAVING'], self::LIST_AND )
1182                                 : $options['HAVING'];
1183                         $sql .= ' HAVING ' . $having;
1184                 }
1185
1186                 return $sql;
1187         }
1188
1189         /**
1190          * Returns an optional ORDER BY
1191          *
1192          * @param array $options Associative array of options
1193          * @return string
1194          * @see DatabaseBase::select()
1195          * @since 1.21
1196          */
1197         public function makeOrderBy( $options ) {
1198                 if ( isset( $options['ORDER BY'] ) ) {
1199                         $ob = is_array( $options['ORDER BY'] )
1200                                 ? implode( ',', $options['ORDER BY'] )
1201                                 : $options['ORDER BY'];
1202
1203                         return ' ORDER BY ' . $ob;
1204                 }
1205
1206                 return '';
1207         }
1208
1209         // See IDatabase::select for the docs for this function
1210         public function select( $table, $vars, $conds = '', $fname = __METHOD__,
1211                 $options = [], $join_conds = [] ) {
1212                 $sql = $this->selectSQLText( $table, $vars, $conds, $fname, $options, $join_conds );
1213
1214                 return $this->query( $sql, $fname );
1215         }
1216
1217         public function selectSQLText( $table, $vars, $conds = '', $fname = __METHOD__,
1218                 $options = [], $join_conds = []
1219         ) {
1220                 if ( is_array( $vars ) ) {
1221                         $vars = implode( ',', $this->fieldNamesWithAlias( $vars ) );
1222                 }
1223
1224                 $options = (array)$options;
1225                 $useIndexes = ( isset( $options['USE INDEX'] ) && is_array( $options['USE INDEX'] ) )
1226                         ? $options['USE INDEX']
1227                         : [];
1228                 $ignoreIndexes = ( isset( $options['IGNORE INDEX'] ) && is_array( $options['IGNORE INDEX'] ) )
1229                         ? $options['IGNORE INDEX']
1230                         : [];
1231
1232                 if ( is_array( $table ) ) {
1233                         $from = ' FROM ' .
1234                                 $this->tableNamesWithIndexClauseOrJOIN( $table, $useIndexes, $ignoreIndexes, $join_conds );
1235                 } elseif ( $table != '' ) {
1236                         if ( $table[0] == ' ' ) {
1237                                 $from = ' FROM ' . $table;
1238                         } else {
1239                                 $from = ' FROM ' .
1240                                         $this->tableNamesWithIndexClauseOrJOIN( [ $table ], $useIndexes, $ignoreIndexes, [] );
1241                         }
1242                 } else {
1243                         $from = '';
1244                 }
1245
1246                 list( $startOpts, $useIndex, $preLimitTail, $postLimitTail, $ignoreIndex ) =
1247                         $this->makeSelectOptions( $options );
1248
1249                 if ( !empty( $conds ) ) {
1250                         if ( is_array( $conds ) ) {
1251                                 $conds = $this->makeList( $conds, self::LIST_AND );
1252                         }
1253                         $sql = "SELECT $startOpts $vars $from $useIndex $ignoreIndex WHERE $conds $preLimitTail";
1254                 } else {
1255                         $sql = "SELECT $startOpts $vars $from $useIndex $ignoreIndex $preLimitTail";
1256                 }
1257
1258                 if ( isset( $options['LIMIT'] ) ) {
1259                         $sql = $this->limitResult( $sql, $options['LIMIT'],
1260                                 isset( $options['OFFSET'] ) ? $options['OFFSET'] : false );
1261                 }
1262                 $sql = "$sql $postLimitTail";
1263
1264                 if ( isset( $options['EXPLAIN'] ) ) {
1265                         $sql = 'EXPLAIN ' . $sql;
1266                 }
1267
1268                 return $sql;
1269         }
1270
1271         public function selectRow( $table, $vars, $conds, $fname = __METHOD__,
1272                 $options = [], $join_conds = []
1273         ) {
1274                 $options = (array)$options;
1275                 $options['LIMIT'] = 1;
1276                 $res = $this->select( $table, $vars, $conds, $fname, $options, $join_conds );
1277
1278                 if ( $res === false ) {
1279                         return false;
1280                 }
1281
1282                 if ( !$this->numRows( $res ) ) {
1283                         return false;
1284                 }
1285
1286                 $obj = $this->fetchObject( $res );
1287
1288                 return $obj;
1289         }
1290
1291         public function estimateRowCount(
1292                 $table, $vars = '*', $conds = '', $fname = __METHOD__, $options = []
1293         ) {
1294                 $rows = 0;
1295                 $res = $this->select( $table, [ 'rowcount' => 'COUNT(*)' ], $conds, $fname, $options );
1296
1297                 if ( $res ) {
1298                         $row = $this->fetchRow( $res );
1299                         $rows = ( isset( $row['rowcount'] ) ) ? (int)$row['rowcount'] : 0;
1300                 }
1301
1302                 return $rows;
1303         }
1304
1305         public function selectRowCount(
1306                 $tables, $vars = '*', $conds = '', $fname = __METHOD__, $options = [], $join_conds = []
1307         ) {
1308                 $rows = 0;
1309                 $sql = $this->selectSQLText( $tables, '1', $conds, $fname, $options, $join_conds );
1310                 $res = $this->query( "SELECT COUNT(*) AS rowcount FROM ($sql) tmp_count", $fname );
1311
1312                 if ( $res ) {
1313                         $row = $this->fetchRow( $res );
1314                         $rows = ( isset( $row['rowcount'] ) ) ? (int)$row['rowcount'] : 0;
1315                 }
1316
1317                 return $rows;
1318         }
1319
1320         /**
1321          * Removes most variables from an SQL query and replaces them with X or N for numbers.
1322          * It's only slightly flawed. Don't use for anything important.
1323          *
1324          * @param string $sql A SQL Query
1325          *
1326          * @return string
1327          */
1328         protected static function generalizeSQL( $sql ) {
1329                 # This does the same as the regexp below would do, but in such a way
1330                 # as to avoid crashing php on some large strings.
1331                 # $sql = preg_replace( "/'([^\\\\']|\\\\.)*'|\"([^\\\\\"]|\\\\.)*\"/", "'X'", $sql );
1332
1333                 $sql = str_replace( "\\\\", '', $sql );
1334                 $sql = str_replace( "\\'", '', $sql );
1335                 $sql = str_replace( "\\\"", '', $sql );
1336                 $sql = preg_replace( "/'.*'/s", "'X'", $sql );
1337                 $sql = preg_replace( '/".*"/s', "'X'", $sql );
1338
1339                 # All newlines, tabs, etc replaced by single space
1340                 $sql = preg_replace( '/\s+/', ' ', $sql );
1341
1342                 # All numbers => N,
1343                 # except the ones surrounded by characters, e.g. l10n
1344                 $sql = preg_replace( '/-?\d+(,-?\d+)+/s', 'N,...,N', $sql );
1345                 $sql = preg_replace( '/(?<![a-zA-Z])-?\d+(?![a-zA-Z])/s', 'N', $sql );
1346
1347                 return $sql;
1348         }
1349
1350         public function fieldExists( $table, $field, $fname = __METHOD__ ) {
1351                 $info = $this->fieldInfo( $table, $field );
1352
1353                 return (bool)$info;
1354         }
1355
1356         public function indexExists( $table, $index, $fname = __METHOD__ ) {
1357                 if ( !$this->tableExists( $table ) ) {
1358                         return null;
1359                 }
1360
1361                 $info = $this->indexInfo( $table, $index, $fname );
1362                 if ( is_null( $info ) ) {
1363                         return null;
1364                 } else {
1365                         return $info !== false;
1366                 }
1367         }
1368
1369         public function tableExists( $table, $fname = __METHOD__ ) {
1370                 $table = $this->tableName( $table );
1371                 $old = $this->ignoreErrors( true );
1372                 $res = $this->query( "SELECT 1 FROM $table LIMIT 1", $fname );
1373                 $this->ignoreErrors( $old );
1374
1375                 return (bool)$res;
1376         }
1377
1378         public function indexUnique( $table, $index ) {
1379                 $indexInfo = $this->indexInfo( $table, $index );
1380
1381                 if ( !$indexInfo ) {
1382                         return null;
1383                 }
1384
1385                 return !$indexInfo[0]->Non_unique;
1386         }
1387
1388         /**
1389          * Helper for DatabaseBase::insert().
1390          *
1391          * @param array $options
1392          * @return string
1393          */
1394         protected function makeInsertOptions( $options ) {
1395                 return implode( ' ', $options );
1396         }
1397
1398         public function insert( $table, $a, $fname = __METHOD__, $options = [] ) {
1399                 # No rows to insert, easy just return now
1400                 if ( !count( $a ) ) {
1401                         return true;
1402                 }
1403
1404                 $table = $this->tableName( $table );
1405
1406                 if ( !is_array( $options ) ) {
1407                         $options = [ $options ];
1408                 }
1409
1410                 $fh = null;
1411                 if ( isset( $options['fileHandle'] ) ) {
1412                         $fh = $options['fileHandle'];
1413                 }
1414                 $options = $this->makeInsertOptions( $options );
1415
1416                 if ( isset( $a[0] ) && is_array( $a[0] ) ) {
1417                         $multi = true;
1418                         $keys = array_keys( $a[0] );
1419                 } else {
1420                         $multi = false;
1421                         $keys = array_keys( $a );
1422                 }
1423
1424                 $sql = 'INSERT ' . $options .
1425                         " INTO $table (" . implode( ',', $keys ) . ') VALUES ';
1426
1427                 if ( $multi ) {
1428                         $first = true;
1429                         foreach ( $a as $row ) {
1430                                 if ( $first ) {
1431                                         $first = false;
1432                                 } else {
1433                                         $sql .= ',';
1434                                 }
1435                                 $sql .= '(' . $this->makeList( $row ) . ')';
1436                         }
1437                 } else {
1438                         $sql .= '(' . $this->makeList( $a ) . ')';
1439                 }
1440
1441                 if ( $fh !== null && false === fwrite( $fh, $sql ) ) {
1442                         return false;
1443                 } elseif ( $fh !== null ) {
1444                         return true;
1445                 }
1446
1447                 return (bool)$this->query( $sql, $fname );
1448         }
1449
1450         /**
1451          * Make UPDATE options array for DatabaseBase::makeUpdateOptions
1452          *
1453          * @param array $options
1454          * @return array
1455          */
1456         protected function makeUpdateOptionsArray( $options ) {
1457                 if ( !is_array( $options ) ) {
1458                         $options = [ $options ];
1459                 }
1460
1461                 $opts = [];
1462
1463                 if ( in_array( 'IGNORE', $options ) ) {
1464                         $opts[] = 'IGNORE';
1465                 }
1466
1467                 return $opts;
1468         }
1469
1470         /**
1471          * Make UPDATE options for the DatabaseBase::update function
1472          *
1473          * @param array $options The options passed to DatabaseBase::update
1474          * @return string
1475          */
1476         protected function makeUpdateOptions( $options ) {
1477                 $opts = $this->makeUpdateOptionsArray( $options );
1478
1479                 return implode( ' ', $opts );
1480         }
1481
1482         function update( $table, $values, $conds, $fname = __METHOD__, $options = [] ) {
1483                 $table = $this->tableName( $table );
1484                 $opts = $this->makeUpdateOptions( $options );
1485                 $sql = "UPDATE $opts $table SET " . $this->makeList( $values, self::LIST_SET );
1486
1487                 if ( $conds !== [] && $conds !== '*' ) {
1488                         $sql .= " WHERE " . $this->makeList( $conds, self::LIST_AND );
1489                 }
1490
1491                 return $this->query( $sql, $fname );
1492         }
1493
1494         public function makeList( $a, $mode = self::LIST_COMMA ) {
1495                 if ( !is_array( $a ) ) {
1496                         throw new DBUnexpectedError( $this, __METHOD__ . ' called with incorrect parameters' );
1497                 }
1498
1499                 $first = true;
1500                 $list = '';
1501
1502                 foreach ( $a as $field => $value ) {
1503                         if ( !$first ) {
1504                                 if ( $mode == self::LIST_AND ) {
1505                                         $list .= ' AND ';
1506                                 } elseif ( $mode == self::LIST_OR ) {
1507                                         $list .= ' OR ';
1508                                 } else {
1509                                         $list .= ',';
1510                                 }
1511                         } else {
1512                                 $first = false;
1513                         }
1514
1515                         if ( ( $mode == self::LIST_AND || $mode == self::LIST_OR ) && is_numeric( $field ) ) {
1516                                 $list .= "($value)";
1517                         } elseif ( $mode == self::LIST_SET && is_numeric( $field ) ) {
1518                                 $list .= "$value";
1519                         } elseif (
1520                                 ( $mode == self::LIST_AND || $mode == self::LIST_OR ) && is_array( $value )
1521                         ) {
1522                                 // Remove null from array to be handled separately if found
1523                                 $includeNull = false;
1524                                 foreach ( array_keys( $value, null, true ) as $nullKey ) {
1525                                         $includeNull = true;
1526                                         unset( $value[$nullKey] );
1527                                 }
1528                                 if ( count( $value ) == 0 && !$includeNull ) {
1529                                         throw new InvalidArgumentException(
1530                                                 __METHOD__ . ": empty input for field $field" );
1531                                 } elseif ( count( $value ) == 0 ) {
1532                                         // only check if $field is null
1533                                         $list .= "$field IS NULL";
1534                                 } else {
1535                                         // IN clause contains at least one valid element
1536                                         if ( $includeNull ) {
1537                                                 // Group subconditions to ensure correct precedence
1538                                                 $list .= '(';
1539                                         }
1540                                         if ( count( $value ) == 1 ) {
1541                                                 // Special-case single values, as IN isn't terribly efficient
1542                                                 // Don't necessarily assume the single key is 0; we don't
1543                                                 // enforce linear numeric ordering on other arrays here.
1544                                                 $value = array_values( $value )[0];
1545                                                 $list .= $field . " = " . $this->addQuotes( $value );
1546                                         } else {
1547                                                 $list .= $field . " IN (" . $this->makeList( $value ) . ") ";
1548                                         }
1549                                         // if null present in array, append IS NULL
1550                                         if ( $includeNull ) {
1551                                                 $list .= " OR $field IS NULL)";
1552                                         }
1553                                 }
1554                         } elseif ( $value === null ) {
1555                                 if ( $mode == self::LIST_AND || $mode == self::LIST_OR ) {
1556                                         $list .= "$field IS ";
1557                                 } elseif ( $mode == self::LIST_SET ) {
1558                                         $list .= "$field = ";
1559                                 }
1560                                 $list .= 'NULL';
1561                         } else {
1562                                 if (
1563                                         $mode == self::LIST_AND || $mode == self::LIST_OR || $mode == self::LIST_SET
1564                                 ) {
1565                                         $list .= "$field = ";
1566                                 }
1567                                 $list .= $mode == self::LIST_NAMES ? $value : $this->addQuotes( $value );
1568                         }
1569                 }
1570
1571                 return $list;
1572         }
1573
1574         public function makeWhereFrom2d( $data, $baseKey, $subKey ) {
1575                 $conds = [];
1576
1577                 foreach ( $data as $base => $sub ) {
1578                         if ( count( $sub ) ) {
1579                                 $conds[] = $this->makeList(
1580                                         [ $baseKey => $base, $subKey => array_keys( $sub ) ],
1581                                         self::LIST_AND );
1582                         }
1583                 }
1584
1585                 if ( $conds ) {
1586                         return $this->makeList( $conds, self::LIST_OR );
1587                 } else {
1588                         // Nothing to search for...
1589                         return false;
1590                 }
1591         }
1592
1593         /**
1594          * Return aggregated value alias
1595          *
1596          * @param array $valuedata
1597          * @param string $valuename
1598          *
1599          * @return string
1600          */
1601         public function aggregateValue( $valuedata, $valuename = 'value' ) {
1602                 return $valuename;
1603         }
1604
1605         public function bitNot( $field ) {
1606                 return "(~$field)";
1607         }
1608
1609         public function bitAnd( $fieldLeft, $fieldRight ) {
1610                 return "($fieldLeft & $fieldRight)";
1611         }
1612
1613         public function bitOr( $fieldLeft, $fieldRight ) {
1614                 return "($fieldLeft | $fieldRight)";
1615         }
1616
1617         public function buildConcat( $stringList ) {
1618                 return 'CONCAT(' . implode( ',', $stringList ) . ')';
1619         }
1620
1621         public function buildGroupConcatField(
1622                 $delim, $table, $field, $conds = '', $join_conds = []
1623         ) {
1624                 $fld = "GROUP_CONCAT($field SEPARATOR " . $this->addQuotes( $delim ) . ')';
1625
1626                 return '(' . $this->selectSQLText( $table, $fld, $conds, null, [], $join_conds ) . ')';
1627         }
1628
1629         /**
1630          * @param string $field Field or column to cast
1631          * @return string
1632          * @since 1.28
1633          */
1634         public function buildStringCast( $field ) {
1635                 return $field;
1636         }
1637
1638         public function selectDB( $db ) {
1639                 # Stub. Shouldn't cause serious problems if it's not overridden, but
1640                 # if your database engine supports a concept similar to MySQL's
1641                 # databases you may as well.
1642                 $this->mDBname = $db;
1643
1644                 return true;
1645         }
1646
1647         public function getDBname() {
1648                 return $this->mDBname;
1649         }
1650
1651         public function getServer() {
1652                 return $this->mServer;
1653         }
1654
1655         /**
1656          * Format a table name ready for use in constructing an SQL query
1657          *
1658          * This does two important things: it quotes the table names to clean them up,
1659          * and it adds a table prefix if only given a table name with no quotes.
1660          *
1661          * All functions of this object which require a table name call this function
1662          * themselves. Pass the canonical name to such functions. This is only needed
1663          * when calling query() directly.
1664          *
1665          * @note This function does not sanitize user input. It is not safe to use
1666          *   this function to escape user input.
1667          * @param string $name Database table name
1668          * @param string $format One of:
1669          *   quoted - Automatically pass the table name through addIdentifierQuotes()
1670          *            so that it can be used in a query.
1671          *   raw - Do not add identifier quotes to the table name
1672          * @return string Full database name
1673          */
1674         public function tableName( $name, $format = 'quoted' ) {
1675                 # Skip the entire process when we have a string quoted on both ends.
1676                 # Note that we check the end so that we will still quote any use of
1677                 # use of `database`.table. But won't break things if someone wants
1678                 # to query a database table with a dot in the name.
1679                 if ( $this->isQuotedIdentifier( $name ) ) {
1680                         return $name;
1681                 }
1682
1683                 # Lets test for any bits of text that should never show up in a table
1684                 # name. Basically anything like JOIN or ON which are actually part of
1685                 # SQL queries, but may end up inside of the table value to combine
1686                 # sql. Such as how the API is doing.
1687                 # Note that we use a whitespace test rather than a \b test to avoid
1688                 # any remote case where a word like on may be inside of a table name
1689                 # surrounded by symbols which may be considered word breaks.
1690                 if ( preg_match( '/(^|\s)(DISTINCT|JOIN|ON|AS)(\s|$)/i', $name ) !== 0 ) {
1691                         return $name;
1692                 }
1693
1694                 # Split database and table into proper variables.
1695                 # We reverse the explode so that database.table and table both output
1696                 # the correct table.
1697                 $dbDetails = explode( '.', $name, 3 );
1698                 if ( count( $dbDetails ) == 3 ) {
1699                         list( $database, $schema, $table ) = $dbDetails;
1700                         # We don't want any prefix added in this case
1701                         $prefix = '';
1702                 } elseif ( count( $dbDetails ) == 2 ) {
1703                         list( $database, $table ) = $dbDetails;
1704                         # We don't want any prefix added in this case
1705                         # In dbs that support it, $database may actually be the schema
1706                         # but that doesn't affect any of the functionality here
1707                         $prefix = '';
1708                         $schema = '';
1709                 } else {
1710                         list( $table ) = $dbDetails;
1711                         if ( isset( $this->tableAliases[$table] ) ) {
1712                                 $database = $this->tableAliases[$table]['dbname'];
1713                                 $schema = is_string( $this->tableAliases[$table]['schema'] )
1714                                         ? $this->tableAliases[$table]['schema']
1715                                         : $this->mSchema;
1716                                 $prefix = is_string( $this->tableAliases[$table]['prefix'] )
1717                                         ? $this->tableAliases[$table]['prefix']
1718                                         : $this->mTablePrefix;
1719                         } else {
1720                                 $database = '';
1721                                 $schema = $this->mSchema; # Default schema
1722                                 $prefix = $this->mTablePrefix; # Default prefix
1723                         }
1724                 }
1725
1726                 # Quote $table and apply the prefix if not quoted.
1727                 # $tableName might be empty if this is called from Database::replaceVars()
1728                 $tableName = "{$prefix}{$table}";
1729                 if ( $format == 'quoted'
1730                         && !$this->isQuotedIdentifier( $tableName ) && $tableName !== ''
1731                 ) {
1732                         $tableName = $this->addIdentifierQuotes( $tableName );
1733                 }
1734
1735                 # Quote $schema and merge it with the table name if needed
1736                 if ( strlen( $schema ) ) {
1737                         if ( $format == 'quoted' && !$this->isQuotedIdentifier( $schema ) ) {
1738                                 $schema = $this->addIdentifierQuotes( $schema );
1739                         }
1740                         $tableName = $schema . '.' . $tableName;
1741                 }
1742
1743                 # Quote $database and merge it with the table name if needed
1744                 if ( $database !== '' ) {
1745                         if ( $format == 'quoted' && !$this->isQuotedIdentifier( $database ) ) {
1746                                 $database = $this->addIdentifierQuotes( $database );
1747                         }
1748                         $tableName = $database . '.' . $tableName;
1749                 }
1750
1751                 return $tableName;
1752         }
1753
1754         /**
1755          * Fetch a number of table names into an array
1756          * This is handy when you need to construct SQL for joins
1757          *
1758          * Example:
1759          * extract( $dbr->tableNames( 'user', 'watchlist' ) );
1760          * $sql = "SELECT wl_namespace,wl_title FROM $watchlist,$user
1761          *         WHERE wl_user=user_id AND wl_user=$nameWithQuotes";
1762          *
1763          * @return array
1764          */
1765         public function tableNames() {
1766                 $inArray = func_get_args();
1767                 $retVal = [];
1768
1769                 foreach ( $inArray as $name ) {
1770                         $retVal[$name] = $this->tableName( $name );
1771                 }
1772
1773                 return $retVal;
1774         }
1775
1776         /**
1777          * Fetch a number of table names into an zero-indexed numerical array
1778          * This is handy when you need to construct SQL for joins
1779          *
1780          * Example:
1781          * list( $user, $watchlist ) = $dbr->tableNamesN( 'user', 'watchlist' );
1782          * $sql = "SELECT wl_namespace,wl_title FROM $watchlist,$user
1783          *         WHERE wl_user=user_id AND wl_user=$nameWithQuotes";
1784          *
1785          * @return array
1786          */
1787         public function tableNamesN() {
1788                 $inArray = func_get_args();
1789                 $retVal = [];
1790
1791                 foreach ( $inArray as $name ) {
1792                         $retVal[] = $this->tableName( $name );
1793                 }
1794
1795                 return $retVal;
1796         }
1797
1798         /**
1799          * Get an aliased table name
1800          * e.g. tableName AS newTableName
1801          *
1802          * @param string $name Table name, see tableName()
1803          * @param string|bool $alias Alias (optional)
1804          * @return string SQL name for aliased table. Will not alias a table to its own name
1805          */
1806         public function tableNameWithAlias( $name, $alias = false ) {
1807                 if ( !$alias || $alias == $name ) {
1808                         return $this->tableName( $name );
1809                 } else {
1810                         return $this->tableName( $name ) . ' ' . $this->addIdentifierQuotes( $alias );
1811                 }
1812         }
1813
1814         /**
1815          * Gets an array of aliased table names
1816          *
1817          * @param array $tables [ [alias] => table ]
1818          * @return string[] See tableNameWithAlias()
1819          */
1820         public function tableNamesWithAlias( $tables ) {
1821                 $retval = [];
1822                 foreach ( $tables as $alias => $table ) {
1823                         if ( is_numeric( $alias ) ) {
1824                                 $alias = $table;
1825                         }
1826                         $retval[] = $this->tableNameWithAlias( $table, $alias );
1827                 }
1828
1829                 return $retval;
1830         }
1831
1832         /**
1833          * Get an aliased field name
1834          * e.g. fieldName AS newFieldName
1835          *
1836          * @param string $name Field name
1837          * @param string|bool $alias Alias (optional)
1838          * @return string SQL name for aliased field. Will not alias a field to its own name
1839          */
1840         public function fieldNameWithAlias( $name, $alias = false ) {
1841                 if ( !$alias || (string)$alias === (string)$name ) {
1842                         return $name;
1843                 } else {
1844                         return $name . ' AS ' . $this->addIdentifierQuotes( $alias ); // PostgreSQL needs AS
1845                 }
1846         }
1847
1848         /**
1849          * Gets an array of aliased field names
1850          *
1851          * @param array $fields [ [alias] => field ]
1852          * @return string[] See fieldNameWithAlias()
1853          */
1854         public function fieldNamesWithAlias( $fields ) {
1855                 $retval = [];
1856                 foreach ( $fields as $alias => $field ) {
1857                         if ( is_numeric( $alias ) ) {
1858                                 $alias = $field;
1859                         }
1860                         $retval[] = $this->fieldNameWithAlias( $field, $alias );
1861                 }
1862
1863                 return $retval;
1864         }
1865
1866         /**
1867          * Get the aliased table name clause for a FROM clause
1868          * which might have a JOIN and/or USE INDEX or IGNORE INDEX clause
1869          *
1870          * @param array $tables ( [alias] => table )
1871          * @param array $use_index Same as for select()
1872          * @param array $ignore_index Same as for select()
1873          * @param array $join_conds Same as for select()
1874          * @return string
1875          */
1876         protected function tableNamesWithIndexClauseOrJOIN(
1877                 $tables, $use_index = [], $ignore_index = [], $join_conds = []
1878         ) {
1879                 $ret = [];
1880                 $retJOIN = [];
1881                 $use_index = (array)$use_index;
1882                 $ignore_index = (array)$ignore_index;
1883                 $join_conds = (array)$join_conds;
1884
1885                 foreach ( $tables as $alias => $table ) {
1886                         if ( !is_string( $alias ) ) {
1887                                 // No alias? Set it equal to the table name
1888                                 $alias = $table;
1889                         }
1890                         // Is there a JOIN clause for this table?
1891                         if ( isset( $join_conds[$alias] ) ) {
1892                                 list( $joinType, $conds ) = $join_conds[$alias];
1893                                 $tableClause = $joinType;
1894                                 $tableClause .= ' ' . $this->tableNameWithAlias( $table, $alias );
1895                                 if ( isset( $use_index[$alias] ) ) { // has USE INDEX?
1896                                         $use = $this->useIndexClause( implode( ',', (array)$use_index[$alias] ) );
1897                                         if ( $use != '' ) {
1898                                                 $tableClause .= ' ' . $use;
1899                                         }
1900                                 }
1901                                 if ( isset( $ignore_index[$alias] ) ) { // has IGNORE INDEX?
1902                                         $ignore = $this->ignoreIndexClause( implode( ',', (array)$ignore_index[$alias] ) );
1903                                         if ( $ignore != '' ) {
1904                                                 $tableClause .= ' ' . $ignore;
1905                                         }
1906                                 }
1907                                 $on = $this->makeList( (array)$conds, self::LIST_AND );
1908                                 if ( $on != '' ) {
1909                                         $tableClause .= ' ON (' . $on . ')';
1910                                 }
1911
1912                                 $retJOIN[] = $tableClause;
1913                         } elseif ( isset( $use_index[$alias] ) ) {
1914                                 // Is there an INDEX clause for this table?
1915                                 $tableClause = $this->tableNameWithAlias( $table, $alias );
1916                                 $tableClause .= ' ' . $this->useIndexClause(
1917                                                 implode( ',', (array)$use_index[$alias] )
1918                                         );
1919
1920                                 $ret[] = $tableClause;
1921                         } elseif ( isset( $ignore_index[$alias] ) ) {
1922                                 // Is there an INDEX clause for this table?
1923                                 $tableClause = $this->tableNameWithAlias( $table, $alias );
1924                                 $tableClause .= ' ' . $this->ignoreIndexClause(
1925                                                 implode( ',', (array)$ignore_index[$alias] )
1926                                         );
1927
1928                                 $ret[] = $tableClause;
1929                         } else {
1930                                 $tableClause = $this->tableNameWithAlias( $table, $alias );
1931
1932                                 $ret[] = $tableClause;
1933                         }
1934                 }
1935
1936                 // We can't separate explicit JOIN clauses with ',', use ' ' for those
1937                 $implicitJoins = !empty( $ret ) ? implode( ',', $ret ) : "";
1938                 $explicitJoins = !empty( $retJOIN ) ? implode( ' ', $retJOIN ) : "";
1939
1940                 // Compile our final table clause
1941                 return implode( ' ', [ $implicitJoins, $explicitJoins ] );
1942         }
1943
1944         /**
1945          * Get the name of an index in a given table.
1946          *
1947          * @param string $index
1948          * @return string
1949          */
1950         protected function indexName( $index ) {
1951                 // Backwards-compatibility hack
1952                 $renamed = [
1953                         'ar_usertext_timestamp' => 'usertext_timestamp',
1954                         'un_user_id' => 'user_id',
1955                         'un_user_ip' => 'user_ip',
1956                 ];
1957
1958                 if ( isset( $renamed[$index] ) ) {
1959                         return $renamed[$index];
1960                 } else {
1961                         return $index;
1962                 }
1963         }
1964
1965         public function addQuotes( $s ) {
1966                 if ( $s instanceof Blob ) {
1967                         $s = $s->fetch();
1968                 }
1969                 if ( $s === null ) {
1970                         return 'NULL';
1971                 } else {
1972                         # This will also quote numeric values. This should be harmless,
1973                         # and protects against weird problems that occur when they really
1974                         # _are_ strings such as article titles and string->number->string
1975                         # conversion is not 1:1.
1976                         return "'" . $this->strencode( $s ) . "'";
1977                 }
1978         }
1979
1980         /**
1981          * Quotes an identifier using `backticks` or "double quotes" depending on the database type.
1982          * MySQL uses `backticks` while basically everything else uses double quotes.
1983          * Since MySQL is the odd one out here the double quotes are our generic
1984          * and we implement backticks in DatabaseMysql.
1985          *
1986          * @param string $s
1987          * @return string
1988          */
1989         public function addIdentifierQuotes( $s ) {
1990                 return '"' . str_replace( '"', '""', $s ) . '"';
1991         }
1992
1993         /**
1994          * Returns if the given identifier looks quoted or not according to
1995          * the database convention for quoting identifiers .
1996          *
1997          * @note Do not use this to determine if untrusted input is safe.
1998          *   A malicious user can trick this function.
1999          * @param string $name
2000          * @return bool
2001          */
2002         public function isQuotedIdentifier( $name ) {
2003                 return $name[0] == '"' && substr( $name, -1, 1 ) == '"';
2004         }
2005
2006         /**
2007          * @param string $s
2008          * @return string
2009          */
2010         protected function escapeLikeInternal( $s ) {
2011                 return addcslashes( $s, '\%_' );
2012         }
2013
2014         public function buildLike() {
2015                 $params = func_get_args();
2016
2017                 if ( count( $params ) > 0 && is_array( $params[0] ) ) {
2018                         $params = $params[0];
2019                 }
2020
2021                 $s = '';
2022
2023                 foreach ( $params as $value ) {
2024                         if ( $value instanceof LikeMatch ) {
2025                                 $s .= $value->toString();
2026                         } else {
2027                                 $s .= $this->escapeLikeInternal( $value );
2028                         }
2029                 }
2030
2031                 return " LIKE {$this->addQuotes( $s )} ";
2032         }
2033
2034         public function anyChar() {
2035                 return new LikeMatch( '_' );
2036         }
2037
2038         public function anyString() {
2039                 return new LikeMatch( '%' );
2040         }
2041
2042         public function nextSequenceValue( $seqName ) {
2043                 return null;
2044         }
2045
2046         /**
2047          * USE INDEX clause. Unlikely to be useful for anything but MySQL. This
2048          * is only needed because a) MySQL must be as efficient as possible due to
2049          * its use on Wikipedia, and b) MySQL 4.0 is kind of dumb sometimes about
2050          * which index to pick. Anyway, other databases might have different
2051          * indexes on a given table. So don't bother overriding this unless you're
2052          * MySQL.
2053          * @param string $index
2054          * @return string
2055          */
2056         public function useIndexClause( $index ) {
2057                 return '';
2058         }
2059
2060         /**
2061          * IGNORE INDEX clause. Unlikely to be useful for anything but MySQL. This
2062          * is only needed because a) MySQL must be as efficient as possible due to
2063          * its use on Wikipedia, and b) MySQL 4.0 is kind of dumb sometimes about
2064          * which index to pick. Anyway, other databases might have different
2065          * indexes on a given table. So don't bother overriding this unless you're
2066          * MySQL.
2067          * @param string $index
2068          * @return string
2069          */
2070         public function ignoreIndexClause( $index ) {
2071                 return '';
2072         }
2073
2074         public function replace( $table, $uniqueIndexes, $rows, $fname = __METHOD__ ) {
2075                 $quotedTable = $this->tableName( $table );
2076
2077                 if ( count( $rows ) == 0 ) {
2078                         return;
2079                 }
2080
2081                 # Single row case
2082                 if ( !is_array( reset( $rows ) ) ) {
2083                         $rows = [ $rows ];
2084                 }
2085
2086                 // @FXIME: this is not atomic, but a trx would break affectedRows()
2087                 foreach ( $rows as $row ) {
2088                         # Delete rows which collide
2089                         if ( $uniqueIndexes ) {
2090                                 $sql = "DELETE FROM $quotedTable WHERE ";
2091                                 $first = true;
2092                                 foreach ( $uniqueIndexes as $index ) {
2093                                         if ( $first ) {
2094                                                 $first = false;
2095                                                 $sql .= '( ';
2096                                         } else {
2097                                                 $sql .= ' ) OR ( ';
2098                                         }
2099                                         if ( is_array( $index ) ) {
2100                                                 $first2 = true;
2101                                                 foreach ( $index as $col ) {
2102                                                         if ( $first2 ) {
2103                                                                 $first2 = false;
2104                                                         } else {
2105                                                                 $sql .= ' AND ';
2106                                                         }
2107                                                         $sql .= $col . '=' . $this->addQuotes( $row[$col] );
2108                                                 }
2109                                         } else {
2110                                                 $sql .= $index . '=' . $this->addQuotes( $row[$index] );
2111                                         }
2112                                 }
2113                                 $sql .= ' )';
2114                                 $this->query( $sql, $fname );
2115                         }
2116
2117                         # Now insert the row
2118                         $this->insert( $table, $row, $fname );
2119                 }
2120         }
2121
2122         /**
2123          * REPLACE query wrapper for MySQL and SQLite, which have a native REPLACE
2124          * statement.
2125          *
2126          * @param string $table Table name
2127          * @param array|string $rows Row(s) to insert
2128          * @param string $fname Caller function name
2129          *
2130          * @return ResultWrapper
2131          */
2132         protected function nativeReplace( $table, $rows, $fname ) {
2133                 $table = $this->tableName( $table );
2134
2135                 # Single row case
2136                 if ( !is_array( reset( $rows ) ) ) {
2137                         $rows = [ $rows ];
2138                 }
2139
2140                 $sql = "REPLACE INTO $table (" . implode( ',', array_keys( $rows[0] ) ) . ') VALUES ';
2141                 $first = true;
2142
2143                 foreach ( $rows as $row ) {
2144                         if ( $first ) {
2145                                 $first = false;
2146                         } else {
2147                                 $sql .= ',';
2148                         }
2149
2150                         $sql .= '(' . $this->makeList( $row ) . ')';
2151                 }
2152
2153                 return $this->query( $sql, $fname );
2154         }
2155
2156         public function upsert( $table, array $rows, array $uniqueIndexes, array $set,
2157                 $fname = __METHOD__
2158         ) {
2159                 if ( !count( $rows ) ) {
2160                         return true; // nothing to do
2161                 }
2162
2163                 if ( !is_array( reset( $rows ) ) ) {
2164                         $rows = [ $rows ];
2165                 }
2166
2167                 if ( count( $uniqueIndexes ) ) {
2168                         $clauses = []; // list WHERE clauses that each identify a single row
2169                         foreach ( $rows as $row ) {
2170                                 foreach ( $uniqueIndexes as $index ) {
2171                                         $index = is_array( $index ) ? $index : [ $index ]; // columns
2172                                         $rowKey = []; // unique key to this row
2173                                         foreach ( $index as $column ) {
2174                                                 $rowKey[$column] = $row[$column];
2175                                         }
2176                                         $clauses[] = $this->makeList( $rowKey, self::LIST_AND );
2177                                 }
2178                         }
2179                         $where = [ $this->makeList( $clauses, self::LIST_OR ) ];
2180                 } else {
2181                         $where = false;
2182                 }
2183
2184                 $useTrx = !$this->mTrxLevel;
2185                 if ( $useTrx ) {
2186                         $this->begin( $fname, self::TRANSACTION_INTERNAL );
2187                 }
2188                 try {
2189                         # Update any existing conflicting row(s)
2190                         if ( $where !== false ) {
2191                                 $ok = $this->update( $table, $set, $where, $fname );
2192                         } else {
2193                                 $ok = true;
2194                         }
2195                         # Now insert any non-conflicting row(s)
2196                         $ok = $this->insert( $table, $rows, $fname, [ 'IGNORE' ] ) && $ok;
2197                 } catch ( Exception $e ) {
2198                         if ( $useTrx ) {
2199                                 $this->rollback( $fname, self::FLUSHING_INTERNAL );
2200                         }
2201                         throw $e;
2202                 }
2203                 if ( $useTrx ) {
2204                         $this->commit( $fname, self::FLUSHING_INTERNAL );
2205                 }
2206
2207                 return $ok;
2208         }
2209
2210         public function deleteJoin( $delTable, $joinTable, $delVar, $joinVar, $conds,
2211                 $fname = __METHOD__
2212         ) {
2213                 if ( !$conds ) {
2214                         throw new DBUnexpectedError( $this, __METHOD__ . ' called with empty $conds' );
2215                 }
2216
2217                 $delTable = $this->tableName( $delTable );
2218                 $joinTable = $this->tableName( $joinTable );
2219                 $sql = "DELETE FROM $delTable WHERE $delVar IN (SELECT $joinVar FROM $joinTable ";
2220                 if ( $conds != '*' ) {
2221                         $sql .= 'WHERE ' . $this->makeList( $conds, self::LIST_AND );
2222                 }
2223                 $sql .= ')';
2224
2225                 $this->query( $sql, $fname );
2226         }
2227
2228         /**
2229          * Returns the size of a text field, or -1 for "unlimited"
2230          *
2231          * @param string $table
2232          * @param string $field
2233          * @return int
2234          */
2235         public function textFieldSize( $table, $field ) {
2236                 $table = $this->tableName( $table );
2237                 $sql = "SHOW COLUMNS FROM $table LIKE \"$field\";";
2238                 $res = $this->query( $sql, __METHOD__ );
2239                 $row = $this->fetchObject( $res );
2240
2241                 $m = [];
2242
2243                 if ( preg_match( '/\((.*)\)/', $row->Type, $m ) ) {
2244                         $size = $m[1];
2245                 } else {
2246                         $size = -1;
2247                 }
2248
2249                 return $size;
2250         }
2251
2252         public function delete( $table, $conds, $fname = __METHOD__ ) {
2253                 if ( !$conds ) {
2254                         throw new DBUnexpectedError( $this, __METHOD__ . ' called with no conditions' );
2255                 }
2256
2257                 $table = $this->tableName( $table );
2258                 $sql = "DELETE FROM $table";
2259
2260                 if ( $conds != '*' ) {
2261                         if ( is_array( $conds ) ) {
2262                                 $conds = $this->makeList( $conds, self::LIST_AND );
2263                         }
2264                         $sql .= ' WHERE ' . $conds;
2265                 }
2266
2267                 return $this->query( $sql, $fname );
2268         }
2269
2270         public function insertSelect(
2271                 $destTable, $srcTable, $varMap, $conds,
2272                 $fname = __METHOD__, $insertOptions = [], $selectOptions = []
2273         ) {
2274                 if ( $this->cliMode ) {
2275                         // For massive migrations with downtime, we don't want to select everything
2276                         // into memory and OOM, so do all this native on the server side if possible.
2277                         return $this->nativeInsertSelect(
2278                                 $destTable,
2279                                 $srcTable,
2280                                 $varMap,
2281                                 $conds,
2282                                 $fname,
2283                                 $insertOptions,
2284                                 $selectOptions
2285                         );
2286                 }
2287
2288                 // For web requests, do a locking SELECT and then INSERT. This puts the SELECT burden
2289                 // on only the master (without needing row-based-replication). It also makes it easy to
2290                 // know how big the INSERT is going to be.
2291                 $fields = [];
2292                 foreach ( $varMap as $dstColumn => $sourceColumnOrSql ) {
2293                         $fields[] = $this->fieldNameWithAlias( $sourceColumnOrSql, $dstColumn );
2294                 }
2295                 $selectOptions[] = 'FOR UPDATE';
2296                 $res = $this->select( $srcTable, implode( ',', $fields ), $conds, $fname, $selectOptions );
2297                 if ( !$res ) {
2298                         return false;
2299                 }
2300
2301                 $rows = [];
2302                 foreach ( $res as $row ) {
2303                         $rows[] = (array)$row;
2304                 }
2305
2306                 return $this->insert( $destTable, $rows, $fname, $insertOptions );
2307         }
2308
2309         public function nativeInsertSelect( $destTable, $srcTable, $varMap, $conds,
2310                 $fname = __METHOD__,
2311                 $insertOptions = [], $selectOptions = []
2312         ) {
2313                 $destTable = $this->tableName( $destTable );
2314
2315                 if ( !is_array( $insertOptions ) ) {
2316                         $insertOptions = [ $insertOptions ];
2317                 }
2318
2319                 $insertOptions = $this->makeInsertOptions( $insertOptions );
2320
2321                 if ( !is_array( $selectOptions ) ) {
2322                         $selectOptions = [ $selectOptions ];
2323                 }
2324
2325                 list( $startOpts, $useIndex, $tailOpts, $ignoreIndex ) = $this->makeSelectOptions(
2326                         $selectOptions );
2327
2328                 if ( is_array( $srcTable ) ) {
2329                         $srcTable = implode( ',', array_map( [ &$this, 'tableName' ], $srcTable ) );
2330                 } else {
2331                         $srcTable = $this->tableName( $srcTable );
2332                 }
2333
2334                 $sql = "INSERT $insertOptions INTO $destTable (" . implode( ',', array_keys( $varMap ) ) . ')' .
2335                         " SELECT $startOpts " . implode( ',', $varMap ) .
2336                         " FROM $srcTable $useIndex $ignoreIndex ";
2337
2338                 if ( $conds != '*' ) {
2339                         if ( is_array( $conds ) ) {
2340                                 $conds = $this->makeList( $conds, self::LIST_AND );
2341                         }
2342                         $sql .= " WHERE $conds";
2343                 }
2344
2345                 $sql .= " $tailOpts";
2346
2347                 return $this->query( $sql, $fname );
2348         }
2349
2350         /**
2351          * Construct a LIMIT query with optional offset. This is used for query
2352          * pages. The SQL should be adjusted so that only the first $limit rows
2353          * are returned. If $offset is provided as well, then the first $offset
2354          * rows should be discarded, and the next $limit rows should be returned.
2355          * If the result of the query is not ordered, then the rows to be returned
2356          * are theoretically arbitrary.
2357          *
2358          * $sql is expected to be a SELECT, if that makes a difference.
2359          *
2360          * The version provided by default works in MySQL and SQLite. It will very
2361          * likely need to be overridden for most other DBMSes.
2362          *
2363          * @param string $sql SQL query we will append the limit too
2364          * @param int $limit The SQL limit
2365          * @param int|bool $offset The SQL offset (default false)
2366          * @throws DBUnexpectedError
2367          * @return string
2368          */
2369         public function limitResult( $sql, $limit, $offset = false ) {
2370                 if ( !is_numeric( $limit ) ) {
2371                         throw new DBUnexpectedError( $this, "Invalid non-numeric limit passed to limitResult()\n" );
2372                 }
2373
2374                 return "$sql LIMIT "
2375                 . ( ( is_numeric( $offset ) && $offset != 0 ) ? "{$offset}," : "" )
2376                 . "{$limit} ";
2377         }
2378
2379         public function unionSupportsOrderAndLimit() {
2380                 return true; // True for almost every DB supported
2381         }
2382
2383         public function unionQueries( $sqls, $all ) {
2384                 $glue = $all ? ') UNION ALL (' : ') UNION (';
2385
2386                 return '(' . implode( $glue, $sqls ) . ')';
2387         }
2388
2389         public function conditional( $cond, $trueVal, $falseVal ) {
2390                 if ( is_array( $cond ) ) {
2391                         $cond = $this->makeList( $cond, self::LIST_AND );
2392                 }
2393
2394                 return " (CASE WHEN $cond THEN $trueVal ELSE $falseVal END) ";
2395         }
2396
2397         public function strreplace( $orig, $old, $new ) {
2398                 return "REPLACE({$orig}, {$old}, {$new})";
2399         }
2400
2401         public function getServerUptime() {
2402                 return 0;
2403         }
2404
2405         public function wasDeadlock() {
2406                 return false;
2407         }
2408
2409         public function wasLockTimeout() {
2410                 return false;
2411         }
2412
2413         public function wasErrorReissuable() {
2414                 return false;
2415         }
2416
2417         public function wasReadOnlyError() {
2418                 return false;
2419         }
2420
2421         /**
2422          * Determines if the given query error was a connection drop
2423          * STUB
2424          *
2425          * @param integer|string $errno
2426          * @return bool
2427          */
2428         public function wasConnectionError( $errno ) {
2429                 return false;
2430         }
2431
2432         /**
2433          * Perform a deadlock-prone transaction.
2434          *
2435          * This function invokes a callback function to perform a set of write
2436          * queries. If a deadlock occurs during the processing, the transaction
2437          * will be rolled back and the callback function will be called again.
2438          *
2439          * Avoid using this method outside of Job or Maintenance classes.
2440          *
2441          * Usage:
2442          *   $dbw->deadlockLoop( callback, ... );
2443          *
2444          * Extra arguments are passed through to the specified callback function.
2445          * This method requires that no transactions are already active to avoid
2446          * causing premature commits or exceptions.
2447          *
2448          * Returns whatever the callback function returned on its successful,
2449          * iteration, or false on error, for example if the retry limit was
2450          * reached.
2451          *
2452          * @return mixed
2453          * @throws DBUnexpectedError
2454          * @throws Exception
2455          */
2456         public function deadlockLoop() {
2457                 $args = func_get_args();
2458                 $function = array_shift( $args );
2459                 $tries = self::DEADLOCK_TRIES;
2460
2461                 $this->begin( __METHOD__ );
2462
2463                 $retVal = null;
2464                 /** @var Exception $e */
2465                 $e = null;
2466                 do {
2467                         try {
2468                                 $retVal = call_user_func_array( $function, $args );
2469                                 break;
2470                         } catch ( DBQueryError $e ) {
2471                                 if ( $this->wasDeadlock() ) {
2472                                         // Retry after a randomized delay
2473                                         usleep( mt_rand( self::DEADLOCK_DELAY_MIN, self::DEADLOCK_DELAY_MAX ) );
2474                                 } else {
2475                                         // Throw the error back up
2476                                         throw $e;
2477                                 }
2478                         }
2479                 } while ( --$tries > 0 );
2480
2481                 if ( $tries <= 0 ) {
2482                         // Too many deadlocks; give up
2483                         $this->rollback( __METHOD__ );
2484                         throw $e;
2485                 } else {
2486                         $this->commit( __METHOD__ );
2487
2488                         return $retVal;
2489                 }
2490         }
2491
2492         public function masterPosWait( DBMasterPos $pos, $timeout ) {
2493                 # Real waits are implemented in the subclass.
2494                 return 0;
2495         }
2496
2497         public function getSlavePos() {
2498                 # Stub
2499                 return false;
2500         }
2501
2502         public function getMasterPos() {
2503                 # Stub
2504                 return false;
2505         }
2506
2507         public function serverIsReadOnly() {
2508                 return false;
2509         }
2510
2511         final public function onTransactionResolution( callable $callback, $fname = __METHOD__ ) {
2512                 if ( !$this->mTrxLevel ) {
2513                         throw new DBUnexpectedError( $this, "No transaction is active." );
2514                 }
2515                 $this->mTrxEndCallbacks[] = [ $callback, $fname ];
2516         }
2517
2518         final public function onTransactionIdle( callable $callback, $fname = __METHOD__ ) {
2519                 $this->mTrxIdleCallbacks[] = [ $callback, $fname ];
2520                 if ( !$this->mTrxLevel ) {
2521                         $this->runOnTransactionIdleCallbacks( self::TRIGGER_IDLE );
2522                 }
2523         }
2524
2525         final public function onTransactionPreCommitOrIdle( callable $callback, $fname = __METHOD__ ) {
2526                 if ( $this->mTrxLevel ) {
2527                         $this->mTrxPreCommitCallbacks[] = [ $callback, $fname ];
2528                 } else {
2529                         // If no transaction is active, then make one for this callback
2530                         $this->startAtomic( __METHOD__ );
2531                         try {
2532                                 call_user_func( $callback );
2533                                 $this->endAtomic( __METHOD__ );
2534                         } catch ( Exception $e ) {
2535                                 $this->rollback( __METHOD__, self::FLUSHING_INTERNAL );
2536                                 throw $e;
2537                         }
2538                 }
2539         }
2540
2541         final public function setTransactionListener( $name, callable $callback = null ) {
2542                 if ( $callback ) {
2543                         $this->mTrxRecurringCallbacks[$name] = $callback;
2544                 } else {
2545                         unset( $this->mTrxRecurringCallbacks[$name] );
2546                 }
2547         }
2548
2549         /**
2550          * Whether to disable running of post-COMMIT/ROLLBACK callbacks
2551          *
2552          * This method should not be used outside of Database/LoadBalancer
2553          *
2554          * @param bool $suppress
2555          * @since 1.28
2556          */
2557         final public function setTrxEndCallbackSuppression( $suppress ) {
2558                 $this->mTrxEndCallbacksSuppressed = $suppress;
2559         }
2560
2561         /**
2562          * Actually run and consume any "on transaction idle/resolution" callbacks.
2563          *
2564          * This method should not be used outside of Database/LoadBalancer
2565          *
2566          * @param integer $trigger IDatabase::TRIGGER_* constant
2567          * @since 1.20
2568          * @throws Exception
2569          */
2570         public function runOnTransactionIdleCallbacks( $trigger ) {
2571                 if ( $this->mTrxEndCallbacksSuppressed ) {
2572                         return;
2573                 }
2574
2575                 $autoTrx = $this->getFlag( DBO_TRX ); // automatic begin() enabled?
2576                 /** @var Exception $e */
2577                 $e = null; // first exception
2578                 do { // callbacks may add callbacks :)
2579                         $callbacks = array_merge(
2580                                 $this->mTrxIdleCallbacks,
2581                                 $this->mTrxEndCallbacks // include "transaction resolution" callbacks
2582                         );
2583                         $this->mTrxIdleCallbacks = []; // consumed (and recursion guard)
2584                         $this->mTrxEndCallbacks = []; // consumed (recursion guard)
2585                         foreach ( $callbacks as $callback ) {
2586                                 try {
2587                                         list( $phpCallback ) = $callback;
2588                                         $this->clearFlag( DBO_TRX ); // make each query its own transaction
2589                                         call_user_func_array( $phpCallback, [ $trigger ] );
2590                                         if ( $autoTrx ) {
2591                                                 $this->setFlag( DBO_TRX ); // restore automatic begin()
2592                                         } else {
2593                                                 $this->clearFlag( DBO_TRX ); // restore auto-commit
2594                                         }
2595                                 } catch ( Exception $ex ) {
2596                                         call_user_func( $this->errorLogger, $ex );
2597                                         $e = $e ?: $ex;
2598                                         // Some callbacks may use startAtomic/endAtomic, so make sure
2599                                         // their transactions are ended so other callbacks don't fail
2600                                         if ( $this->trxLevel() ) {
2601                                                 $this->rollback( __METHOD__, self::FLUSHING_INTERNAL );
2602                                         }
2603                                 }
2604                         }
2605                 } while ( count( $this->mTrxIdleCallbacks ) );
2606
2607                 if ( $e instanceof Exception ) {
2608                         throw $e; // re-throw any first exception
2609                 }
2610         }
2611
2612         /**
2613          * Actually run and consume any "on transaction pre-commit" callbacks.
2614          *
2615          * This method should not be used outside of Database/LoadBalancer
2616          *
2617          * @since 1.22
2618          * @throws Exception
2619          */
2620         public function runOnTransactionPreCommitCallbacks() {
2621                 $e = null; // first exception
2622                 do { // callbacks may add callbacks :)
2623                         $callbacks = $this->mTrxPreCommitCallbacks;
2624                         $this->mTrxPreCommitCallbacks = []; // consumed (and recursion guard)
2625                         foreach ( $callbacks as $callback ) {
2626                                 try {
2627                                         list( $phpCallback ) = $callback;
2628                                         call_user_func( $phpCallback );
2629                                 } catch ( Exception $ex ) {
2630                                         call_user_func( $this->errorLogger, $ex );
2631                                         $e = $e ?: $ex;
2632                                 }
2633                         }
2634                 } while ( count( $this->mTrxPreCommitCallbacks ) );
2635
2636                 if ( $e instanceof Exception ) {
2637                         throw $e; // re-throw any first exception
2638                 }
2639         }
2640
2641         /**
2642          * Actually run any "transaction listener" callbacks.
2643          *
2644          * This method should not be used outside of Database/LoadBalancer
2645          *
2646          * @param integer $trigger IDatabase::TRIGGER_* constant
2647          * @throws Exception
2648          * @since 1.20
2649          */
2650         public function runTransactionListenerCallbacks( $trigger ) {
2651                 if ( $this->mTrxEndCallbacksSuppressed ) {
2652                         return;
2653                 }
2654
2655                 /** @var Exception $e */
2656                 $e = null; // first exception
2657
2658                 foreach ( $this->mTrxRecurringCallbacks as $phpCallback ) {
2659                         try {
2660                                 $phpCallback( $trigger, $this );
2661                         } catch ( Exception $ex ) {
2662                                 call_user_func( $this->errorLogger, $ex );
2663                                 $e = $e ?: $ex;
2664                         }
2665                 }
2666
2667                 if ( $e instanceof Exception ) {
2668                         throw $e; // re-throw any first exception
2669                 }
2670         }
2671
2672         final public function startAtomic( $fname = __METHOD__ ) {
2673                 if ( !$this->mTrxLevel ) {
2674                         $this->begin( $fname, self::TRANSACTION_INTERNAL );
2675                         // If DBO_TRX is set, a series of startAtomic/endAtomic pairs will result
2676                         // in all changes being in one transaction to keep requests transactional.
2677                         if ( !$this->getFlag( DBO_TRX ) ) {
2678                                 $this->mTrxAutomaticAtomic = true;
2679                         }
2680                 }
2681
2682                 $this->mTrxAtomicLevels[] = $fname;
2683         }
2684
2685         final public function endAtomic( $fname = __METHOD__ ) {
2686                 if ( !$this->mTrxLevel ) {
2687                         throw new DBUnexpectedError( $this, "No atomic transaction is open (got $fname)." );
2688                 }
2689                 if ( !$this->mTrxAtomicLevels ||
2690                         array_pop( $this->mTrxAtomicLevels ) !== $fname
2691                 ) {
2692                         throw new DBUnexpectedError( $this, "Invalid atomic section ended (got $fname)." );
2693                 }
2694
2695                 if ( !$this->mTrxAtomicLevels && $this->mTrxAutomaticAtomic ) {
2696                         $this->commit( $fname, self::FLUSHING_INTERNAL );
2697                 }
2698         }
2699
2700         final public function doAtomicSection( $fname, callable $callback ) {
2701                 $this->startAtomic( $fname );
2702                 try {
2703                         $res = call_user_func_array( $callback, [ $this, $fname ] );
2704                 } catch ( Exception $e ) {
2705                         $this->rollback( $fname, self::FLUSHING_INTERNAL );
2706                         throw $e;
2707                 }
2708                 $this->endAtomic( $fname );
2709
2710                 return $res;
2711         }
2712
2713         final public function begin( $fname = __METHOD__, $mode = self::TRANSACTION_EXPLICIT ) {
2714                 // Protect against mismatched atomic section, transaction nesting, and snapshot loss
2715                 if ( $this->mTrxLevel ) {
2716                         if ( $this->mTrxAtomicLevels ) {
2717                                 $levels = implode( ', ', $this->mTrxAtomicLevels );
2718                                 $msg = "$fname: Got explicit BEGIN while atomic section(s) $levels are open.";
2719                                 throw new DBUnexpectedError( $this, $msg );
2720                         } elseif ( !$this->mTrxAutomatic ) {
2721                                 $msg = "$fname: Explicit transaction already active (from {$this->mTrxFname}).";
2722                                 throw new DBUnexpectedError( $this, $msg );
2723                         } else {
2724                                 // @TODO: make this an exception at some point
2725                                 $msg = "$fname: Implicit transaction already active (from {$this->mTrxFname}).";
2726                                 $this->queryLogger->error( $msg );
2727                                 return; // join the main transaction set
2728                         }
2729                 } elseif ( $this->getFlag( DBO_TRX ) && $mode !== self::TRANSACTION_INTERNAL ) {
2730                         // @TODO: make this an exception at some point
2731                         $msg = "$fname: Implicit transaction expected (DBO_TRX set).";
2732                         $this->queryLogger->error( $msg );
2733                         return; // let any writes be in the main transaction
2734                 }
2735
2736                 // Avoid fatals if close() was called
2737                 $this->assertOpen();
2738
2739                 $this->doBegin( $fname );
2740                 $this->mTrxTimestamp = microtime( true );
2741                 $this->mTrxFname = $fname;
2742                 $this->mTrxDoneWrites = false;
2743                 $this->mTrxAutomatic = ( $mode === self::TRANSACTION_INTERNAL );
2744                 $this->mTrxAutomaticAtomic = false;
2745                 $this->mTrxAtomicLevels = [];
2746                 $this->mTrxShortId = sprintf( '%06x', mt_rand( 0, 0xffffff ) );
2747                 $this->mTrxWriteDuration = 0.0;
2748                 $this->mTrxWriteQueryCount = 0;
2749                 $this->mTrxWriteAdjDuration = 0.0;
2750                 $this->mTrxWriteAdjQueryCount = 0;
2751                 $this->mTrxWriteCallers = [];
2752                 // First SELECT after BEGIN will establish the snapshot in REPEATABLE-READ.
2753                 // Get an estimate of the replica DB lag before then, treating estimate staleness
2754                 // as lag itself just to be safe
2755                 $status = $this->getApproximateLagStatus();
2756                 $this->mTrxReplicaLag = $status['lag'] + ( microtime( true ) - $status['since'] );
2757         }
2758
2759         /**
2760          * Issues the BEGIN command to the database server.
2761          *
2762          * @see DatabaseBase::begin()
2763          * @param string $fname
2764          */
2765         protected function doBegin( $fname ) {
2766                 $this->query( 'BEGIN', $fname );
2767                 $this->mTrxLevel = 1;
2768         }
2769
2770         final public function commit( $fname = __METHOD__, $flush = '' ) {
2771                 if ( $this->mTrxLevel && $this->mTrxAtomicLevels ) {
2772                         // There are still atomic sections open. This cannot be ignored
2773                         $levels = implode( ', ', $this->mTrxAtomicLevels );
2774                         throw new DBUnexpectedError(
2775                                 $this,
2776                                 "$fname: Got COMMIT while atomic sections $levels are still open."
2777                         );
2778                 }
2779
2780                 if ( $flush === self::FLUSHING_INTERNAL || $flush === self::FLUSHING_ALL_PEERS ) {
2781                         if ( !$this->mTrxLevel ) {
2782                                 return; // nothing to do
2783                         } elseif ( !$this->mTrxAutomatic ) {
2784                                 throw new DBUnexpectedError(
2785                                         $this,
2786                                         "$fname: Flushing an explicit transaction, getting out of sync."
2787                                 );
2788                         }
2789                 } else {
2790                         if ( !$this->mTrxLevel ) {
2791                                 $this->queryLogger->error( "$fname: No transaction to commit, something got out of sync." );
2792                                 return; // nothing to do
2793                         } elseif ( $this->mTrxAutomatic ) {
2794                                 // @TODO: make this an exception at some point
2795                                 $msg = "$fname: Explicit commit of implicit transaction.";
2796                                 $this->queryLogger->error( $msg );
2797                                 return; // wait for the main transaction set commit round
2798                         }
2799                 }
2800
2801                 // Avoid fatals if close() was called
2802                 $this->assertOpen();
2803
2804                 $this->runOnTransactionPreCommitCallbacks();
2805                 $writeTime = $this->pendingWriteQueryDuration( self::ESTIMATE_DB_APPLY );
2806                 $this->doCommit( $fname );
2807                 if ( $this->mTrxDoneWrites ) {
2808                         $this->mDoneWrites = microtime( true );
2809                         $this->trxProfiler->transactionWritingOut(
2810                                 $this->mServer, $this->mDBname, $this->mTrxShortId, $writeTime );
2811                 }
2812
2813                 $this->runOnTransactionIdleCallbacks( self::TRIGGER_COMMIT );
2814                 $this->runTransactionListenerCallbacks( self::TRIGGER_COMMIT );
2815         }
2816
2817         /**
2818          * Issues the COMMIT command to the database server.
2819          *
2820          * @see DatabaseBase::commit()
2821          * @param string $fname
2822          */
2823         protected function doCommit( $fname ) {
2824                 if ( $this->mTrxLevel ) {
2825                         $this->query( 'COMMIT', $fname );
2826                         $this->mTrxLevel = 0;
2827                 }
2828         }
2829
2830         final public function rollback( $fname = __METHOD__, $flush = '' ) {
2831                 if ( $flush === self::FLUSHING_INTERNAL || $flush === self::FLUSHING_ALL_PEERS ) {
2832                         if ( !$this->mTrxLevel ) {
2833                                 return; // nothing to do
2834                         }
2835                 } else {
2836                         if ( !$this->mTrxLevel ) {
2837                                 $this->queryLogger->error(
2838                                         "$fname: No transaction to rollback, something got out of sync." );
2839                                 return; // nothing to do
2840                         } elseif ( $this->getFlag( DBO_TRX ) ) {
2841                                 throw new DBUnexpectedError(
2842                                         $this,
2843                                         "$fname: Expected mass rollback of all peer databases (DBO_TRX set)."
2844                                 );
2845                         }
2846                 }
2847
2848                 // Avoid fatals if close() was called
2849                 $this->assertOpen();
2850
2851                 $this->doRollback( $fname );
2852                 $this->mTrxAtomicLevels = [];
2853                 if ( $this->mTrxDoneWrites ) {
2854                         $this->trxProfiler->transactionWritingOut(
2855                                 $this->mServer, $this->mDBname, $this->mTrxShortId );
2856                 }
2857
2858                 $this->mTrxIdleCallbacks = []; // clear
2859                 $this->mTrxPreCommitCallbacks = []; // clear
2860                 $this->runOnTransactionIdleCallbacks( self::TRIGGER_ROLLBACK );
2861                 $this->runTransactionListenerCallbacks( self::TRIGGER_ROLLBACK );
2862         }
2863
2864         /**
2865          * Issues the ROLLBACK command to the database server.
2866          *
2867          * @see DatabaseBase::rollback()
2868          * @param string $fname
2869          */
2870         protected function doRollback( $fname ) {
2871                 if ( $this->mTrxLevel ) {
2872                         # Disconnects cause rollback anyway, so ignore those errors
2873                         $ignoreErrors = true;
2874                         $this->query( 'ROLLBACK', $fname, $ignoreErrors );
2875                         $this->mTrxLevel = 0;
2876                 }
2877         }
2878
2879         public function flushSnapshot( $fname = __METHOD__ ) {
2880                 if ( $this->writesOrCallbacksPending() || $this->explicitTrxActive() ) {
2881                         // This only flushes transactions to clear snapshots, not to write data
2882                         $fnames = implode( ', ', $this->pendingWriteAndCallbackCallers() );
2883                         throw new DBUnexpectedError(
2884                                 $this,
2885                                 "$fname: Cannot COMMIT to clear snapshot because writes are pending ($fnames)."
2886                         );
2887                 }
2888
2889                 $this->commit( $fname, self::FLUSHING_INTERNAL );
2890         }
2891
2892         public function explicitTrxActive() {
2893                 return $this->mTrxLevel && ( $this->mTrxAtomicLevels || !$this->mTrxAutomatic );
2894         }
2895
2896         /**
2897          * Creates a new table with structure copied from existing table
2898          * Note that unlike most database abstraction functions, this function does not
2899          * automatically append database prefix, because it works at a lower
2900          * abstraction level.
2901          * The table names passed to this function shall not be quoted (this
2902          * function calls addIdentifierQuotes when needed).
2903          *
2904          * @param string $oldName Name of table whose structure should be copied
2905          * @param string $newName Name of table to be created
2906          * @param bool $temporary Whether the new table should be temporary
2907          * @param string $fname Calling function name
2908          * @throws RuntimeException
2909          * @return bool True if operation was successful
2910          */
2911         public function duplicateTableStructure( $oldName, $newName, $temporary = false,
2912                 $fname = __METHOD__
2913         ) {
2914                 throw new RuntimeException( __METHOD__ . ' is not implemented in descendant class' );
2915         }
2916
2917         function listTables( $prefix = null, $fname = __METHOD__ ) {
2918                 throw new RuntimeException( __METHOD__ . ' is not implemented in descendant class' );
2919         }
2920
2921         /**
2922          * Reset the views process cache set by listViews()
2923          * @since 1.22
2924          */
2925         final public function clearViewsCache() {
2926                 $this->allViews = null;
2927         }
2928
2929         /**
2930          * Lists all the VIEWs in the database
2931          *
2932          * For caching purposes the list of all views should be stored in
2933          * $this->allViews. The process cache can be cleared with clearViewsCache()
2934          *
2935          * @param string $prefix Only show VIEWs with this prefix, eg. unit_test_
2936          * @param string $fname Name of calling function
2937          * @throws RuntimeException
2938          * @return array
2939          * @since 1.22
2940          */
2941         public function listViews( $prefix = null, $fname = __METHOD__ ) {
2942                 throw new RuntimeException( __METHOD__ . ' is not implemented in descendant class' );
2943         }
2944
2945         /**
2946          * Differentiates between a TABLE and a VIEW
2947          *
2948          * @param string $name Name of the database-structure to test.
2949          * @throws RuntimeException
2950          * @return bool
2951          * @since 1.22
2952          */
2953         public function isView( $name ) {
2954                 throw new RuntimeException( __METHOD__ . ' is not implemented in descendant class' );
2955         }
2956
2957         public function timestamp( $ts = 0 ) {
2958                 $t = new ConvertableTimestamp( $ts );
2959                 // Let errors bubble up to avoid putting garbage in the DB
2960                 return $t->getTimestamp( TS_MW );
2961         }
2962
2963         public function timestampOrNull( $ts = null ) {
2964                 if ( is_null( $ts ) ) {
2965                         return null;
2966                 } else {
2967                         return $this->timestamp( $ts );
2968                 }
2969         }
2970
2971         /**
2972          * Take the result from a query, and wrap it in a ResultWrapper if
2973          * necessary. Boolean values are passed through as is, to indicate success
2974          * of write queries or failure.
2975          *
2976          * Once upon a time, DatabaseBase::query() returned a bare MySQL result
2977          * resource, and it was necessary to call this function to convert it to
2978          * a wrapper. Nowadays, raw database objects are never exposed to external
2979          * callers, so this is unnecessary in external code.
2980          *
2981          * @param bool|ResultWrapper|resource|object $result
2982          * @return bool|ResultWrapper
2983          */
2984         protected function resultObject( $result ) {
2985                 if ( !$result ) {
2986                         return false;
2987                 } elseif ( $result instanceof ResultWrapper ) {
2988                         return $result;
2989                 } elseif ( $result === true ) {
2990                         // Successful write query
2991                         return $result;
2992                 } else {
2993                         return new ResultWrapper( $this, $result );
2994                 }
2995         }
2996
2997         public function ping( &$rtt = null ) {
2998                 // Avoid hitting the server if it was hit recently
2999                 if ( $this->isOpen() && ( microtime( true ) - $this->lastPing ) < self::PING_TTL ) {
3000                         if ( !func_num_args() || $this->mRTTEstimate > 0 ) {
3001                                 $rtt = $this->mRTTEstimate;
3002                                 return true; // don't care about $rtt
3003                         }
3004                 }
3005
3006                 // This will reconnect if possible or return false if not
3007                 $this->clearFlag( DBO_TRX, self::REMEMBER_PRIOR );
3008                 $ok = ( $this->query( self::PING_QUERY, __METHOD__, true ) !== false );
3009                 $this->restoreFlags( self::RESTORE_PRIOR );
3010
3011                 if ( $ok ) {
3012                         $rtt = $this->mRTTEstimate;
3013                 }
3014
3015                 return $ok;
3016         }
3017
3018         /**
3019          * @return bool
3020          */
3021         protected function reconnect() {
3022                 $this->closeConnection();
3023                 $this->mOpened = false;
3024                 $this->mConn = false;
3025                 try {
3026                         $this->open( $this->mServer, $this->mUser, $this->mPassword, $this->mDBname );
3027                         $this->lastPing = microtime( true );
3028                         $ok = true;
3029                 } catch ( DBConnectionError $e ) {
3030                         $ok = false;
3031                 }
3032
3033                 return $ok;
3034         }
3035
3036         public function getSessionLagStatus() {
3037                 return $this->getTransactionLagStatus() ?: $this->getApproximateLagStatus();
3038         }
3039
3040         /**
3041          * Get the replica DB lag when the current transaction started
3042          *
3043          * This is useful when transactions might use snapshot isolation
3044          * (e.g. REPEATABLE-READ in innodb), so the "real" lag of that data
3045          * is this lag plus transaction duration. If they don't, it is still
3046          * safe to be pessimistic. This returns null if there is no transaction.
3047          *
3048          * @return array|null ('lag': seconds or false on error, 'since': UNIX timestamp of BEGIN)
3049          * @since 1.27
3050          */
3051         public function getTransactionLagStatus() {
3052                 return $this->mTrxLevel
3053                         ? [ 'lag' => $this->mTrxReplicaLag, 'since' => $this->trxTimestamp() ]
3054                         : null;
3055         }
3056
3057         /**
3058          * Get a replica DB lag estimate for this server
3059          *
3060          * @return array ('lag': seconds or false on error, 'since': UNIX timestamp of estimate)
3061          * @since 1.27
3062          */
3063         public function getApproximateLagStatus() {
3064                 return [
3065                         'lag'   => $this->getLBInfo( 'replica' ) ? $this->getLag() : 0,
3066                         'since' => microtime( true )
3067                 ];
3068         }
3069
3070         /**
3071          * Merge the result of getSessionLagStatus() for several DBs
3072          * using the most pessimistic values to estimate the lag of
3073          * any data derived from them in combination
3074          *
3075          * This is information is useful for caching modules
3076          *
3077          * @see WANObjectCache::set()
3078          * @see WANObjectCache::getWithSetCallback()
3079          *
3080          * @param IDatabase $db1
3081          * @param IDatabase ...
3082          * @return array Map of values:
3083          *   - lag: highest lag of any of the DBs or false on error (e.g. replication stopped)
3084          *   - since: oldest UNIX timestamp of any of the DB lag estimates
3085          *   - pending: whether any of the DBs have uncommitted changes
3086          * @since 1.27
3087          */
3088         public static function getCacheSetOptions( IDatabase $db1 ) {
3089                 $res = [ 'lag' => 0, 'since' => INF, 'pending' => false ];
3090                 foreach ( func_get_args() as $db ) {
3091                         /** @var IDatabase $db */
3092                         $status = $db->getSessionLagStatus();
3093                         if ( $status['lag'] === false ) {
3094                                 $res['lag'] = false;
3095                         } elseif ( $res['lag'] !== false ) {
3096                                 $res['lag'] = max( $res['lag'], $status['lag'] );
3097                         }
3098                         $res['since'] = min( $res['since'], $status['since'] );
3099                         $res['pending'] = $res['pending'] ?: $db->writesPending();
3100                 }
3101
3102                 return $res;
3103         }
3104
3105         public function getLag() {
3106                 return 0;
3107         }
3108
3109         function maxListLen() {
3110                 return 0;
3111         }
3112
3113         public function encodeBlob( $b ) {
3114                 return $b;
3115         }
3116
3117         public function decodeBlob( $b ) {
3118                 if ( $b instanceof Blob ) {
3119                         $b = $b->fetch();
3120                 }
3121                 return $b;
3122         }
3123
3124         public function setSessionOptions( array $options ) {
3125         }
3126
3127         /**
3128          * Read and execute SQL commands from a file.
3129          *
3130          * Returns true on success, error string or exception on failure (depending
3131          * on object's error ignore settings).
3132          *
3133          * @param string $filename File name to open
3134          * @param bool|callable $lineCallback Optional function called before reading each line
3135          * @param bool|callable $resultCallback Optional function called for each MySQL result
3136          * @param bool|string $fname Calling function name or false if name should be
3137          *   generated dynamically using $filename
3138          * @param bool|callable $inputCallback Optional function called for each
3139          *   complete line sent
3140          * @return bool|string
3141          * @throws Exception
3142          */
3143         public function sourceFile(
3144                 $filename, $lineCallback = false, $resultCallback = false, $fname = false, $inputCallback = false
3145         ) {
3146                 MediaWiki\suppressWarnings();
3147                 $fp = fopen( $filename, 'r' );
3148                 MediaWiki\restoreWarnings();
3149
3150                 if ( false === $fp ) {
3151                         throw new RuntimeException( "Could not open \"{$filename}\".\n" );
3152                 }
3153
3154                 if ( !$fname ) {
3155                         $fname = __METHOD__ . "( $filename )";
3156                 }
3157
3158                 try {
3159                         $error = $this->sourceStream( $fp, $lineCallback, $resultCallback, $fname, $inputCallback );
3160                 } catch ( Exception $e ) {
3161                         fclose( $fp );
3162                         throw $e;
3163                 }
3164
3165                 fclose( $fp );
3166
3167                 return $error;
3168         }
3169
3170         public function setSchemaVars( $vars ) {
3171                 $this->mSchemaVars = $vars;
3172         }
3173
3174         /**
3175          * Read and execute commands from an open file handle.
3176          *
3177          * Returns true on success, error string or exception on failure (depending
3178          * on object's error ignore settings).
3179          *
3180          * @param resource $fp File handle
3181          * @param bool|callable $lineCallback Optional function called before reading each query
3182          * @param bool|callable $resultCallback Optional function called for each MySQL result
3183          * @param string $fname Calling function name
3184          * @param bool|callable $inputCallback Optional function called for each complete query sent
3185          * @return bool|string
3186          */
3187         public function sourceStream( $fp, $lineCallback = false, $resultCallback = false,
3188                 $fname = __METHOD__, $inputCallback = false
3189         ) {
3190                 $cmd = '';
3191
3192                 while ( !feof( $fp ) ) {
3193                         if ( $lineCallback ) {
3194                                 call_user_func( $lineCallback );
3195                         }
3196
3197                         $line = trim( fgets( $fp ) );
3198
3199                         if ( $line == '' ) {
3200                                 continue;
3201                         }
3202
3203                         if ( '-' == $line[0] && '-' == $line[1] ) {
3204                                 continue;
3205                         }
3206
3207                         if ( $cmd != '' ) {
3208                                 $cmd .= ' ';
3209                         }
3210
3211                         $done = $this->streamStatementEnd( $cmd, $line );
3212
3213                         $cmd .= "$line\n";
3214
3215                         if ( $done || feof( $fp ) ) {
3216                                 $cmd = $this->replaceVars( $cmd );
3217
3218                                 if ( ( $inputCallback && call_user_func( $inputCallback, $cmd ) ) || !$inputCallback ) {
3219                                         $res = $this->query( $cmd, $fname );
3220
3221                                         if ( $resultCallback ) {
3222                                                 call_user_func( $resultCallback, $res, $this );
3223                                         }
3224
3225                                         if ( false === $res ) {
3226                                                 $err = $this->lastError();
3227
3228                                                 return "Query \"{$cmd}\" failed with error code \"$err\".\n";
3229                                         }
3230                                 }
3231                                 $cmd = '';
3232                         }
3233                 }
3234
3235                 return true;
3236         }
3237
3238         /**
3239          * Called by sourceStream() to check if we've reached a statement end
3240          *
3241          * @param string $sql SQL assembled so far
3242          * @param string $newLine New line about to be added to $sql
3243          * @return bool Whether $newLine contains end of the statement
3244          */
3245         public function streamStatementEnd( &$sql, &$newLine ) {
3246                 if ( $this->delimiter ) {
3247                         $prev = $newLine;
3248                         $newLine = preg_replace( '/' . preg_quote( $this->delimiter, '/' ) . '$/', '', $newLine );
3249                         if ( $newLine != $prev ) {
3250                                 return true;
3251                         }
3252                 }
3253
3254                 return false;
3255         }
3256
3257         /**
3258          * Database independent variable replacement. Replaces a set of variables
3259          * in an SQL statement with their contents as given by $this->getSchemaVars().
3260          *
3261          * Supports '{$var}' `{$var}` and / *$var* / (without the spaces) style variables.
3262          *
3263          * - '{$var}' should be used for text and is passed through the database's
3264          *   addQuotes method.
3265          * - `{$var}` should be used for identifiers (e.g. table and database names).
3266          *   It is passed through the database's addIdentifierQuotes method which
3267          *   can be overridden if the database uses something other than backticks.
3268          * - / *_* / or / *$wgDBprefix* / passes the name that follows through the
3269          *   database's tableName method.
3270          * - / *i* / passes the name that follows through the database's indexName method.
3271          * - In all other cases, / *$var* / is left unencoded. Except for table options,
3272          *   its use should be avoided. In 1.24 and older, string encoding was applied.
3273          *
3274          * @param string $ins SQL statement to replace variables in
3275          * @return string The new SQL statement with variables replaced
3276          */
3277         protected function replaceVars( $ins ) {
3278                 $vars = $this->getSchemaVars();
3279                 return preg_replace_callback(
3280                         '!
3281                                 /\* (\$wgDBprefix|[_i]) \*/ (\w*) | # 1-2. tableName, indexName
3282                                 \'\{\$ (\w+) }\'                  | # 3. addQuotes
3283                                 `\{\$ (\w+) }`                    | # 4. addIdentifierQuotes
3284                                 /\*\$ (\w+) \*/                     # 5. leave unencoded
3285                         !x',
3286                         function ( $m ) use ( $vars ) {
3287                                 // Note: Because of <https://bugs.php.net/bug.php?id=51881>,
3288                                 // check for both nonexistent keys *and* the empty string.
3289                                 if ( isset( $m[1] ) && $m[1] !== '' ) {
3290                                         if ( $m[1] === 'i' ) {
3291                                                 return $this->indexName( $m[2] );
3292                                         } else {
3293                                                 return $this->tableName( $m[2] );
3294                                         }
3295                                 } elseif ( isset( $m[3] ) && $m[3] !== '' && array_key_exists( $m[3], $vars ) ) {
3296                                         return $this->addQuotes( $vars[$m[3]] );
3297                                 } elseif ( isset( $m[4] ) && $m[4] !== '' && array_key_exists( $m[4], $vars ) ) {
3298                                         return $this->addIdentifierQuotes( $vars[$m[4]] );
3299                                 } elseif ( isset( $m[5] ) && $m[5] !== '' && array_key_exists( $m[5], $vars ) ) {
3300                                         return $vars[$m[5]];
3301                                 } else {
3302                                         return $m[0];
3303                                 }
3304                         },
3305                         $ins
3306                 );
3307         }
3308
3309         /**
3310          * Get schema variables. If none have been set via setSchemaVars(), then
3311          * use some defaults from the current object.
3312          *
3313          * @return array
3314          */
3315         protected function getSchemaVars() {
3316                 if ( $this->mSchemaVars ) {
3317                         return $this->mSchemaVars;
3318                 } else {
3319                         return $this->getDefaultSchemaVars();
3320                 }
3321         }
3322
3323         /**
3324          * Get schema variables to use if none have been set via setSchemaVars().
3325          *
3326          * Override this in derived classes to provide variables for tables.sql
3327          * and SQL patch files.
3328          *
3329          * @return array
3330          */
3331         protected function getDefaultSchemaVars() {
3332                 return [];
3333         }
3334
3335         public function lockIsFree( $lockName, $method ) {
3336                 return true;
3337         }
3338
3339         public function lock( $lockName, $method, $timeout = 5 ) {
3340                 $this->mNamedLocksHeld[$lockName] = 1;
3341
3342                 return true;
3343         }
3344
3345         public function unlock( $lockName, $method ) {
3346                 unset( $this->mNamedLocksHeld[$lockName] );
3347
3348                 return true;
3349         }
3350
3351         public function getScopedLockAndFlush( $lockKey, $fname, $timeout ) {
3352                 if ( $this->writesOrCallbacksPending() ) {
3353                         // This only flushes transactions to clear snapshots, not to write data
3354                         $fnames = implode( ', ', $this->pendingWriteAndCallbackCallers() );
3355                         throw new DBUnexpectedError(
3356                                 $this,
3357                                 "$fname: Cannot COMMIT to clear snapshot because writes are pending ($fnames)."
3358                         );
3359                 }
3360
3361                 if ( !$this->lock( $lockKey, $fname, $timeout ) ) {
3362                         return null;
3363                 }
3364
3365                 $unlocker = new ScopedCallback( function () use ( $lockKey, $fname ) {
3366                         if ( $this->trxLevel() ) {
3367                                 // There is a good chance an exception was thrown, causing any early return
3368                                 // from the caller. Let any error handler get a chance to issue rollback().
3369                                 // If there isn't one, let the error bubble up and trigger server-side rollback.
3370                                 $this->onTransactionResolution(
3371                                         function () use ( $lockKey, $fname ) {
3372                                                 $this->unlock( $lockKey, $fname );
3373                                         },
3374                                         $fname
3375                                 );
3376                         } else {
3377                                 $this->unlock( $lockKey, $fname );
3378                         }
3379                 } );
3380
3381                 $this->commit( $fname, self::FLUSHING_INTERNAL );
3382
3383                 return $unlocker;
3384         }
3385
3386         public function namedLocksEnqueue() {
3387                 return false;
3388         }
3389
3390         /**
3391          * Lock specific tables
3392          *
3393          * @param array $read Array of tables to lock for read access
3394          * @param array $write Array of tables to lock for write access
3395          * @param string $method Name of caller
3396          * @param bool $lowPriority Whether to indicate writes to be LOW PRIORITY
3397          * @return bool
3398          */
3399         public function lockTables( $read, $write, $method, $lowPriority = true ) {
3400                 return true;
3401         }
3402
3403         /**
3404          * Unlock specific tables
3405          *
3406          * @param string $method The caller
3407          * @return bool
3408          */
3409         public function unlockTables( $method ) {
3410                 return true;
3411         }
3412
3413         /**
3414          * Delete a table
3415          * @param string $tableName
3416          * @param string $fName
3417          * @return bool|ResultWrapper
3418          * @since 1.18
3419          */
3420         public function dropTable( $tableName, $fName = __METHOD__ ) {
3421                 if ( !$this->tableExists( $tableName, $fName ) ) {
3422                         return false;
3423                 }
3424                 $sql = "DROP TABLE " . $this->tableName( $tableName ) . " CASCADE";
3425
3426                 return $this->query( $sql, $fName );
3427         }
3428
3429         public function getInfinity() {
3430                 return 'infinity';
3431         }
3432
3433         public function encodeExpiry( $expiry ) {
3434                 return ( $expiry == '' || $expiry == 'infinity' || $expiry == $this->getInfinity() )
3435                         ? $this->getInfinity()
3436                         : $this->timestamp( $expiry );
3437         }
3438
3439         public function decodeExpiry( $expiry, $format = TS_MW ) {
3440                 if ( $expiry == '' || $expiry == 'infinity' || $expiry == $this->getInfinity() ) {
3441                         return 'infinity';
3442                 }
3443
3444                 try {
3445                         $t = new ConvertableTimestamp( $expiry );
3446
3447                         return $t->getTimestamp( $format );
3448                 } catch ( TimestampException $e ) {
3449                         return false;
3450                 }
3451         }
3452
3453         public function setBigSelects( $value = true ) {
3454                 // no-op
3455         }
3456
3457         public function isReadOnly() {
3458                 return ( $this->getReadOnlyReason() !== false );
3459         }
3460
3461         /**
3462          * @return string|bool Reason this DB is read-only or false if it is not
3463          */
3464         protected function getReadOnlyReason() {
3465                 $reason = $this->getLBInfo( 'readOnlyReason' );
3466
3467                 return is_string( $reason ) ? $reason : false;
3468         }
3469
3470         public function setTableAliases( array $aliases ) {
3471                 $this->tableAliases = $aliases;
3472         }
3473
3474         /**
3475          * @return bool Whether a DB user is required to access the DB
3476          * @since 1.28
3477          */
3478         protected function requiresDatabaseUser() {
3479                 return true;
3480         }
3481
3482         /**
3483          * @since 1.19
3484          * @return string
3485          */
3486         public function __toString() {
3487                 return (string)$this->mConn;
3488         }
3489
3490         /**
3491          * Called by serialize. Throw an exception when DB connection is serialized.
3492          * This causes problems on some database engines because the connection is
3493          * not restored on unserialize.
3494          */
3495         public function __sleep() {
3496                 throw new RuntimeException( 'Database serialization may cause problems, since ' .
3497                         'the connection is not restored on wakeup.' );
3498         }
3499
3500         /**
3501          * Run a few simple sanity checks
3502          */
3503         public function __destruct() {
3504                 if ( $this->mTrxLevel && $this->mTrxDoneWrites ) {
3505                         trigger_error( "Uncommitted DB writes (transaction from {$this->mTrxFname})." );
3506                 }
3507
3508                 $danglingWriters = $this->pendingWriteAndCallbackCallers();
3509                 if ( $danglingWriters ) {
3510                         $fnames = implode( ', ', $danglingWriters );
3511                         trigger_error( "DB transaction writes or callbacks still pending ($fnames)." );
3512                 }
3513         }
3514 }