includes/libs/rdbms/database/Database.php

   1 <?php
   2 /**
   3  * @defgroup Database Database
   4  *
   5  * This file deals with database interface functions
   6  * and query specifics/optimisations.
   7  *
   8  * This program is free software; you can redistribute it and/or modify
   9  * it under the terms of the GNU General Public License as published by
  10  * the Free Software Foundation; either version 2 of the License, or
  11  * (at your option) any later version.
  12  *
  13  * This program is distributed in the hope that it will be useful,
  14  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  15  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
  16  * GNU General Public License for more details.
  17  *
  18  * You should have received a copy of the GNU General Public License along
  19  * with this program; if not, write to the Free Software Foundation, Inc.,
  20  * 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
  21  * http://www.gnu.org/copyleft/gpl.html
  22  *
  23  * @file
  24  * @ingroup Database
  25  */
  26 use Psr\Log\LoggerAwareInterface;
  27 use Psr\Log\LoggerInterface;
  28 use Wikimedia\ScopedCallback;
  29
  30 /**
  31  * Relational database abstraction object
  32  *
  33  * @ingroup Database
  34  * @since 1.28
  35  */
  36 abstract class Database implements IDatabase, IMaintainableDatabase, LoggerAwareInterface {
  37         /** Number of times to re-try an operation in case of deadlock */
  38         const DEADLOCK_TRIES = 4;
  39         /** Minimum time to wait before retry, in microseconds */
  40         const DEADLOCK_DELAY_MIN = 500000;
  41         /** Maximum time to wait before retry */
  42         const DEADLOCK_DELAY_MAX = 1500000;
  43
  44         /** How long before it is worth doing a dummy query to test the connection */
  45         const PING_TTL = 1.0;
  46         const PING_QUERY = 'SELECT 1 AS ping';
  47
  48         const TINY_WRITE_SEC = .010;
  49         const SLOW_WRITE_SEC = .500;
  50         const SMALL_WRITE_ROWS = 100;
  51
  52         /** @var string SQL query */
  53         protected $mLastQuery = '';
  54         /** @var float|bool UNIX timestamp of last write query */
  55         protected $mLastWriteTime = false;
  56         /** @var string|bool */
  57         protected $mPHPError = false;
  58         /** @var string */
  59         protected $mServer;
  60         /** @var string */
  61         protected $mUser;
  62         /** @var string */
  63         protected $mPassword;
  64         /** @var string */
  65         protected $mDBname;
  66         /** @var array[] $aliases Map of (table => (dbname, schema, prefix) map) */
  67         protected $tableAliases = [];
  68         /** @var bool Whether this PHP instance is for a CLI script */
  69         protected $cliMode;
  70         /** @var string Agent name for query profiling */
  71         protected $agent;
  72         /** @var array[] Map of (section ID => info map) for usage section IDs */
  73         protected $usageSectionInfo = [];
  74
  75         /** @var BagOStuff APC cache */
  76         protected $srvCache;
  77         /** @var LoggerInterface */
  78         protected $connLogger;
  79         /** @var LoggerInterface */
  80         protected $queryLogger;
  81         /** @var callback Error logging callback */
  82         protected $errorLogger;
  83
  84         /** @var resource|null Database connection */
  85         protected $mConn = null;
  86         /** @var bool */
  87         protected $mOpened = false;
  88
  89         /** @var array[] List of (callable, method name) */
  90         protected $mTrxIdleCallbacks = [];
  91         /** @var array[] List of (callable, method name) */
  92         protected $mTrxPreCommitCallbacks = [];
  93         /** @var array[] List of (callable, method name) */
  94         protected $mTrxEndCallbacks = [];
  95         /** @var callable[] Map of (name => callable) */
  96         protected $mTrxRecurringCallbacks = [];
  97         /** @var bool Whether to suppress triggering of transaction end callbacks */
  98         protected $mTrxEndCallbacksSuppressed = false;
  99
 100         /** @var string */
 101         protected $mTablePrefix = '';
 102         /** @var string */
 103         protected $mSchema = '';
 104         /** @var integer */
 105         protected $mFlags;
 106         /** @var array */
 107         protected $mLBInfo = [];
 108         /** @var bool|null */
 109         protected $mDefaultBigSelects = null;
 110         /** @var array|bool */
 111         protected $mSchemaVars = false;
 112         /** @var array */
 113         protected $mSessionVars = [];
 114         /** @var array|null */
 115         protected $preparedArgs;
 116         /** @var string|bool|null Stashed value of html_errors INI setting */
 117         protected $htmlErrors;
 118         /** @var string */
 119         protected $delimiter = ';';
 120         /** @var DatabaseDomain */
 121         protected $currentDomain;
 122
 123         /**
 124          * Either 1 if a transaction is active or 0 otherwise.
 125          * The other Trx fields may not be meaningfull if this is 0.
 126          *
 127          * @var int
 128          */
 129         protected $mTrxLevel = 0;
 130         /**
 131          * Either a short hexidecimal string if a transaction is active or ""
 132          *
 133          * @var string
 134          * @see Database::mTrxLevel
 135          */
 136         protected $mTrxShortId = '';
 137         /**
 138          * The UNIX time that the transaction started. Callers can assume that if
 139          * snapshot isolation is used, then the data is *at least* up to date to that
 140          * point (possibly more up-to-date since the first SELECT defines the snapshot).
 141          *
 142          * @var float|null
 143          * @see Database::mTrxLevel
 144          */
 145         private $mTrxTimestamp = null;
 146         /** @var float Lag estimate at the time of BEGIN */
 147         private $mTrxReplicaLag = null;
 148         /**
 149          * Remembers the function name given for starting the most recent transaction via begin().
 150          * Used to provide additional context for error reporting.
 151          *
 152          * @var string
 153          * @see Database::mTrxLevel
 154          */
 155         private $mTrxFname = null;
 156         /**
 157          * Record if possible write queries were done in the last transaction started
 158          *
 159          * @var bool
 160          * @see Database::mTrxLevel
 161          */
 162         private $mTrxDoneWrites = false;
 163         /**
 164          * Record if the current transaction was started implicitly due to DBO_TRX being set.
 165          *
 166          * @var bool
 167          * @see Database::mTrxLevel
 168          */
 169         private $mTrxAutomatic = false;
 170         /**
 171          * Array of levels of atomicity within transactions
 172          *
 173          * @var array
 174          */
 175         private $mTrxAtomicLevels = [];
 176         /**
 177          * Record if the current transaction was started implicitly by Database::startAtomic
 178          *
 179          * @var bool
 180          */
 181         private $mTrxAutomaticAtomic = false;
 182         /**
 183          * Track the write query callers of the current transaction
 184          *
 185          * @var string[]
 186          */
 187         private $mTrxWriteCallers = [];
 188         /**
 189          * @var float Seconds spent in write queries for the current transaction
 190          */
 191         private $mTrxWriteDuration = 0.0;
 192         /**
 193          * @var integer Number of write queries for the current transaction
 194          */
 195         private $mTrxWriteQueryCount = 0;
 196         /**
 197          * @var float Like mTrxWriteQueryCount but excludes lock-bound, easy to replicate, queries
 198          */
 199         private $mTrxWriteAdjDuration = 0.0;
 200         /**
 201          * @var integer Number of write queries counted in mTrxWriteAdjDuration
 202          */
 203         private $mTrxWriteAdjQueryCount = 0;
 204         /**
 205          * @var float RTT time estimate
 206          */
 207         private $mRTTEstimate = 0.0;
 208
 209         /** @var array Map of (name => 1) for locks obtained via lock() */
 210         private $mNamedLocksHeld = [];
 211         /** @var array Map of (table name => 1) for TEMPORARY tables */
 212         protected $mSessionTempTables = [];
 213
 214         /** @var IDatabase|null Lazy handle to the master DB this server replicates from */
 215         private $lazyMasterHandle;
 216
 217         /** @var float UNIX timestamp */
 218         protected $lastPing = 0.0;
 219
 220         /** @var int[] Prior mFlags values */
 221         private $priorFlags = [];
 222
 223         /** @var object|string Class name or object With profileIn/profileOut methods */
 224         protected $profiler;
 225         /** @var TransactionProfiler */
 226         protected $trxProfiler;
 227
 228         /**
 229          * Constructor and database handle and attempt to connect to the DB server
 230          *
 231          * IDatabase classes should not be constructed directly in external
 232          * code. Database::factory() should be used instead.
 233          *
 234          * @param array $params Parameters passed from Database::factory()
 235          */
 236         function __construct( array $params ) {
 237                 $server = $params['host'];
 238                 $user = $params['user'];
 239                 $password = $params['password'];
 240                 $dbName = $params['dbname'];
 241
 242                 $this->mSchema = $params['schema'];
 243                 $this->mTablePrefix = $params['tablePrefix'];
 244
 245                 $this->cliMode = $params['cliMode'];
 246                 // Agent name is added to SQL queries in a comment, so make sure it can't break out
 247                 $this->agent = str_replace( '/', '-', $params['agent'] );
 248
 249                 $this->mFlags = $params['flags'];
 250                 if ( $this->mFlags & self::DBO_DEFAULT ) {
 251                         if ( $this->cliMode ) {
 252                                 $this->mFlags &= ~self::DBO_TRX;
 253                         } else {
 254                                 $this->mFlags |= self::DBO_TRX;
 255                         }
 256                 }
 257
 258                 $this->mSessionVars = $params['variables'];
 259
 260                 $this->srvCache = isset( $params['srvCache'] )
 261                         ? $params['srvCache']
 262                         : new HashBagOStuff();
 263
 264                 $this->profiler = $params['profiler'];
 265                 $this->trxProfiler = $params['trxProfiler'];
 266                 $this->connLogger = $params['connLogger'];
 267                 $this->queryLogger = $params['queryLogger'];
 268                 $this->errorLogger = $params['errorLogger'];
 269
 270                 // Set initial dummy domain until open() sets the final DB/prefix
 271                 $this->currentDomain = DatabaseDomain::newUnspecified();
 272
 273                 if ( $user ) {
 274                         $this->open( $server, $user, $password, $dbName );
 275                 } elseif ( $this->requiresDatabaseUser() ) {
 276                         throw new InvalidArgumentException( "No database user provided." );
 277                 }
 278
 279                 // Set the domain object after open() sets the relevant fields
 280                 if ( $this->mDBname != '' ) {
 281                         // Domains with server scope but a table prefix are not used by IDatabase classes
 282                         $this->currentDomain = new DatabaseDomain( $this->mDBname, null, $this->mTablePrefix );
 283                 }
 284         }
 285
 286         /**
 287          * Construct a Database subclass instance given a database type and parameters
 288          *
 289          * This also connects to the database immediately upon object construction
 290          *
 291          * @param string $dbType A possible DB type (sqlite, mysql, postgres)
 292          * @param array $p Parameter map with keys:
 293          *   - host : The hostname of the DB server
 294          *   - user : The name of the database user the client operates under
 295          *   - password : The password for the database user
 296          *   - dbname : The name of the database to use where queries do not specify one.
 297          *      The database must exist or an error might be thrown. Setting this to the empty string
 298          *      will avoid any such errors and make the handle have no implicit database scope. This is
 299          *      useful for queries like SHOW STATUS, CREATE DATABASE, or DROP DATABASE. Note that a
 300          *      "database" in Postgres is rougly equivalent to an entire MySQL server. This the domain
 301          *      in which user names and such are defined, e.g. users are database-specific in Postgres.
 302          *   - schema : The database schema to use (if supported). A "schema" in Postgres is roughly
 303          *      equivalent to a "database" in MySQL. Note that MySQL and SQLite do not use schemas.
 304          *   - tablePrefix : Optional table prefix that is implicitly added on to all table names
 305          *      recognized in queries. This can be used in place of schemas for handle site farms.
 306          *   - flags : Optional bitfield of DBO_* constants that define connection, protocol,
 307          *      buffering, and transaction behavior. It is STRONGLY adviced to leave the DBO_DEFAULT
 308          *      flag in place UNLESS this this database simply acts as a key/value store.
 309          *   - driver: Optional name of a specific DB client driver. For MySQL, there is the old
 310          *      'mysql' driver and the newer 'mysqli' driver.
 311          *   - variables: Optional map of session variables to set after connecting. This can be
 312          *      used to adjust lock timeouts or encoding modes and the like.
 313          *   - connLogger: Optional PSR-3 logger interface instance.
 314          *   - queryLogger: Optional PSR-3 logger interface instance.
 315          *   - profiler: Optional class name or object with profileIn()/profileOut() methods.
 316          *      These will be called in query(), using a simplified version of the SQL that also
 317          *      includes the agent as a SQL comment.
 318          *   - trxProfiler: Optional TransactionProfiler instance.
 319          *   - errorLogger: Optional callback that takes an Exception and logs it.
 320          *   - cliMode: Whether to consider the execution context that of a CLI script.
 321          *   - agent: Optional name used to identify the end-user in query profiling/logging.
 322          *   - srvCache: Optional BagOStuff instance to an APC-style cache.
 323          * @return Database|null If the database driver or extension cannot be found
 324          * @throws InvalidArgumentException If the database driver or extension cannot be found
 325          * @since 1.18
 326          */
 327         final public static function factory( $dbType, $p = [] ) {
 328                 static $canonicalDBTypes = [
 329                         'mysql' => [ 'mysqli', 'mysql' ],
 330                         'postgres' => [],
 331                         'sqlite' => [],
 332                         'oracle' => [],
 333                         'mssql' => [],
 334                 ];
 335
 336                 $driver = false;
 337                 $dbType = strtolower( $dbType );
 338                 if ( isset( $canonicalDBTypes[$dbType] ) && $canonicalDBTypes[$dbType] ) {
 339                         $possibleDrivers = $canonicalDBTypes[$dbType];
 340                         if ( !empty( $p['driver'] ) ) {
 341                                 if ( in_array( $p['driver'], $possibleDrivers ) ) {
 342                                         $driver = $p['driver'];
 343                                 } else {
 344                                         throw new InvalidArgumentException( __METHOD__ .
 345                                                 " type '$dbType' does not support driver '{$p['driver']}'" );
 346                                 }
 347                         } else {
 348                                 foreach ( $possibleDrivers as $posDriver ) {
 349                                         if ( extension_loaded( $posDriver ) ) {
 350                                                 $driver = $posDriver;
 351                                                 break;
 352                                         }
 353                                 }
 354                         }
 355                 } else {
 356                         $driver = $dbType;
 357                 }
 358                 if ( $driver === false || $driver === '' ) {
 359                         throw new InvalidArgumentException( __METHOD__ .
 360                                 " no viable database extension found for type '$dbType'" );
 361                 }
 362
 363                 $class = 'Database' . ucfirst( $driver );
 364                 if ( class_exists( $class ) && is_subclass_of( $class, 'IDatabase' ) ) {
 365                         // Resolve some defaults for b/c
 366                         $p['host'] = isset( $p['host'] ) ? $p['host'] : false;
 367                         $p['user'] = isset( $p['user'] ) ? $p['user'] : false;
 368                         $p['password'] = isset( $p['password'] ) ? $p['password'] : false;
 369                         $p['dbname'] = isset( $p['dbname'] ) ? $p['dbname'] : false;
 370                         $p['flags'] = isset( $p['flags'] ) ? $p['flags'] : 0;
 371                         $p['variables'] = isset( $p['variables'] ) ? $p['variables'] : [];
 372                         $p['tablePrefix'] = isset( $p['tablePrefix'] ) ? $p['tablePrefix'] : '';
 373                         $p['schema'] = isset( $p['schema'] ) ? $p['schema'] : '';
 374                         $p['cliMode'] = isset( $p['cliMode'] ) ? $p['cliMode'] : ( PHP_SAPI === 'cli' );
 375                         $p['agent'] = isset( $p['agent'] ) ? $p['agent'] : '';
 376                         if ( !isset( $p['connLogger'] ) ) {
 377                                 $p['connLogger'] = new \Psr\Log\NullLogger();
 378                         }
 379                         if ( !isset( $p['queryLogger'] ) ) {
 380                                 $p['queryLogger'] = new \Psr\Log\NullLogger();
 381                         }
 382                         $p['profiler'] = isset( $p['profiler'] ) ? $p['profiler'] : null;
 383                         if ( !isset( $p['trxProfiler'] ) ) {
 384                                 $p['trxProfiler'] = new TransactionProfiler();
 385                         }
 386                         if ( !isset( $p['errorLogger'] ) ) {
 387                                 $p['errorLogger'] = function ( Exception $e ) {
 388                                         trigger_error( get_class( $e ) . ': ' . $e->getMessage(), E_USER_WARNING );
 389                                 };
 390                         }
 391
 392                         $conn = new $class( $p );
 393                 } else {
 394                         $conn = null;
 395                 }
 396
 397                 return $conn;
 398         }
 399
 400         public function setLogger( LoggerInterface $logger ) {
 401                 $this->queryLogger = $logger;
 402         }
 403
 404         public function getServerInfo() {
 405                 return $this->getServerVersion();
 406         }
 407
 408         public function bufferResults( $buffer = null ) {
 409                 $res = !$this->getFlag( self::DBO_NOBUFFER );
 410                 if ( $buffer !== null ) {
 411                         $buffer
 412                                 ? $this->clearFlag( self::DBO_NOBUFFER )
 413                                 : $this->setFlag( self::DBO_NOBUFFER );
 414                 }
 415
 416                 return $res;
 417         }
 418
 419         /**
 420          * Turns on (false) or off (true) the automatic generation and sending
 421          * of a "we're sorry, but there has been a database error" page on
 422          * database errors. Default is on (false). When turned off, the
 423          * code should use lastErrno() and lastError() to handle the
 424          * situation as appropriate.
 425          *
 426          * Do not use this function outside of the Database classes.
 427          *
 428          * @param null|bool $ignoreErrors
 429          * @return bool The previous value of the flag.
 430          */
 431         protected function ignoreErrors( $ignoreErrors = null ) {
 432                 $res = $this->getFlag( self::DBO_IGNORE );
 433                 if ( $ignoreErrors !== null ) {
 434                         $ignoreErrors
 435                                 ? $this->setFlag( self::DBO_IGNORE )
 436                                 : $this->clearFlag( self::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         public function getLBInfo( $name = null ) {
 472                 if ( is_null( $name ) ) {
 473                         return $this->mLBInfo;
 474                 } else {
 475                         if ( array_key_exists( $name, $this->mLBInfo ) ) {
 476                                 return $this->mLBInfo[$name];
 477                         } else {
 478                                 return null;
 479                         }
 480                 }
 481         }
 482
 483         public function setLBInfo( $name, $value = null ) {
 484                 if ( is_null( $value ) ) {
 485                         $this->mLBInfo = $name;
 486                 } else {
 487                         $this->mLBInfo[$name] = $value;
 488                 }
 489         }
 490
 491         public function setLazyMasterHandle( IDatabase $conn ) {
 492                 $this->lazyMasterHandle = $conn;
 493         }
 494
 495         /**
 496          * @return IDatabase|null
 497          * @see setLazyMasterHandle()
 498          * @since 1.27
 499          */
 500         protected function getLazyMasterHandle() {
 501                 return $this->lazyMasterHandle;
 502         }
 503
 504         public function implicitGroupby() {
 505                 return true;
 506         }
 507
 508         public function implicitOrderby() {
 509                 return true;
 510         }
 511
 512         public function lastQuery() {
 513                 return $this->mLastQuery;
 514         }
 515
 516         public function doneWrites() {
 517                 return (bool)$this->mLastWriteTime;
 518         }
 519
 520         public function lastDoneWrites() {
 521                 return $this->mLastWriteTime ?: false;
 522         }
 523
 524         public function writesPending() {
 525                 return $this->mTrxLevel && $this->mTrxDoneWrites;
 526         }
 527
 528         public function writesOrCallbacksPending() {
 529                 return $this->mTrxLevel && (
 530                         $this->mTrxDoneWrites || $this->mTrxIdleCallbacks || $this->mTrxPreCommitCallbacks
 531                 );
 532         }
 533
 534         public function pendingWriteQueryDuration( $type = self::ESTIMATE_TOTAL ) {
 535                 if ( !$this->mTrxLevel ) {
 536                         return false;
 537                 } elseif ( !$this->mTrxDoneWrites ) {
 538                         return 0.0;
 539                 }
 540
 541                 switch ( $type ) {
 542                         case self::ESTIMATE_DB_APPLY:
 543                                 $this->ping( $rtt );
 544                                 $rttAdjTotal = $this->mTrxWriteAdjQueryCount * $rtt;
 545                                 $applyTime = max( $this->mTrxWriteAdjDuration - $rttAdjTotal, 0 );
 546                                 // For omitted queries, make them count as something at least
 547                                 $omitted = $this->mTrxWriteQueryCount - $this->mTrxWriteAdjQueryCount;
 548                                 $applyTime += self::TINY_WRITE_SEC * $omitted;
 549
 550                                 return $applyTime;
 551                         default: // everything
 552                                 return $this->mTrxWriteDuration;
 553                 }
 554         }
 555
 556         public function pendingWriteCallers() {
 557                 return $this->mTrxLevel ? $this->mTrxWriteCallers : [];
 558         }
 559
 560         protected function pendingWriteAndCallbackCallers() {
 561                 if ( !$this->mTrxLevel ) {
 562                         return [];
 563                 }
 564
 565                 $fnames = $this->mTrxWriteCallers;
 566                 foreach ( [
 567                         $this->mTrxIdleCallbacks,
 568                         $this->mTrxPreCommitCallbacks,
 569                         $this->mTrxEndCallbacks
 570                 ] as $callbacks ) {
 571                         foreach ( $callbacks as $callback ) {
 572                                 $fnames[] = $callback[1];
 573                         }
 574                 }
 575
 576                 return $fnames;
 577         }
 578
 579         public function isOpen() {
 580                 return $this->mOpened;
 581         }
 582
 583         public function setFlag( $flag, $remember = self::REMEMBER_NOTHING ) {
 584                 if ( $remember === self::REMEMBER_PRIOR ) {
 585                         array_push( $this->priorFlags, $this->mFlags );
 586                 }
 587                 $this->mFlags |= $flag;
 588         }
 589
 590         public function clearFlag( $flag, $remember = self::REMEMBER_NOTHING ) {
 591                 if ( $remember === self::REMEMBER_PRIOR ) {
 592                         array_push( $this->priorFlags, $this->mFlags );
 593                 }
 594                 $this->mFlags &= ~$flag;
 595         }
 596
 597         public function restoreFlags( $state = self::RESTORE_PRIOR ) {
 598                 if ( !$this->priorFlags ) {
 599                         return;
 600                 }
 601
 602                 if ( $state === self::RESTORE_INITIAL ) {
 603                         $this->mFlags = reset( $this->priorFlags );
 604                         $this->priorFlags = [];
 605                 } else {
 606                         $this->mFlags = array_pop( $this->priorFlags );
 607                 }
 608         }
 609
 610         public function getFlag( $flag ) {
 611                 return !!( $this->mFlags & $flag );
 612         }
 613
 614         /**
 615          * @param string $name Class field name
 616          * @return mixed
 617          * @deprecated Since 1.28
 618          */
 619         public function getProperty( $name ) {
 620                 return $this->$name;
 621         }
 622
 623         public function getDomainID() {
 624                 return $this->currentDomain->getId();
 625         }
 626
 627         final public function getWikiID() {
 628                 return $this->getDomainID();
 629         }
 630
 631         /**
 632          * Get information about an index into an object
 633          * @param string $table Table name
 634          * @param string $index Index name
 635          * @param string $fname Calling function name
 636          * @return mixed Database-specific index description class or false if the index does not exist
 637          */
 638         abstract function indexInfo( $table, $index, $fname = __METHOD__ );
 639
 640         /**
 641          * Wrapper for addslashes()
 642          *
 643          * @param string $s String to be slashed.
 644          * @return string Slashed string.
 645          */
 646         abstract function strencode( $s );
 647
 648         protected function installErrorHandler() {
 649                 $this->mPHPError = false;
 650                 $this->htmlErrors = ini_set( 'html_errors', '0' );
 651                 set_error_handler( [ $this, 'connectionErrorLogger' ] );
 652         }
 653
 654         /**
 655          * @return bool|string
 656          */
 657         protected function restoreErrorHandler() {
 658                 restore_error_handler();
 659                 if ( $this->htmlErrors !== false ) {
 660                         ini_set( 'html_errors', $this->htmlErrors );
 661                 }
 662
 663                 return $this->getLastPHPError();
 664         }
 665
 666         /**
 667          * @return string|bool Last PHP error for this DB (typically connection errors)
 668          */
 669         protected function getLastPHPError() {
 670                 if ( $this->mPHPError ) {
 671                         $error = preg_replace( '!\[<a.*</a>\]!', '', $this->mPHPError );
 672                         $error = preg_replace( '!^.*?:\s?(.*)$!', '$1', $error );
 673
 674                         return $error;
 675                 }
 676
 677                 return false;
 678         }
 679
 680         /**
 681          * This method should not be used outside of Database classes
 682          *
 683          * @param int $errno
 684          * @param string $errstr
 685          */
 686         public function connectionErrorLogger( $errno, $errstr ) {
 687                 $this->mPHPError = $errstr;
 688         }
 689
 690         /**
 691          * Create a log context to pass to PSR-3 logger functions.
 692          *
 693          * @param array $extras Additional data to add to context
 694          * @return array
 695          */
 696         protected function getLogContext( array $extras = [] ) {
 697                 return array_merge(
 698                         [
 699                                 'db_server' => $this->mServer,
 700                                 'db_name' => $this->mDBname,
 701                                 'db_user' => $this->mUser,
 702                         ],
 703                         $extras
 704                 );
 705         }
 706
 707         public function close() {
 708                 if ( $this->mConn ) {
 709                         if ( $this->trxLevel() ) {
 710                                 $this->commit( __METHOD__, self::FLUSHING_INTERNAL );
 711                         }
 712
 713                         $closed = $this->closeConnection();
 714                         $this->mConn = false;
 715                 } elseif ( $this->mTrxIdleCallbacks || $this->mTrxEndCallbacks ) { // sanity
 716                         throw new RuntimeException( "Transaction callbacks still pending." );
 717                 } else {
 718                         $closed = true;
 719                 }
 720                 $this->mOpened = false;
 721
 722                 return $closed;
 723         }
 724
 725         /**
 726          * Make sure isOpen() returns true as a sanity check
 727          *
 728          * @throws DBUnexpectedError
 729          */
 730         protected function assertOpen() {
 731                 if ( !$this->isOpen() ) {
 732                         throw new DBUnexpectedError( $this, "DB connection was already closed." );
 733                 }
 734         }
 735
 736         /**
 737          * Closes underlying database connection
 738          * @since 1.20
 739          * @return bool Whether connection was closed successfully
 740          */
 741         abstract protected function closeConnection();
 742
 743         public function reportConnectionError( $error = 'Unknown error' ) {
 744                 $myError = $this->lastError();
 745                 if ( $myError ) {
 746                         $error = $myError;
 747                 }
 748
 749                 # New method
 750                 throw new DBConnectionError( $this, $error );
 751         }
 752
 753         /**
 754          * The DBMS-dependent part of query()
 755          *
 756          * @param string $sql SQL query.
 757          * @return ResultWrapper|bool Result object to feed to fetchObject,
 758          *   fetchRow, ...; or false on failure
 759          */
 760         abstract protected function doQuery( $sql );
 761
 762         /**
 763          * Determine whether a query writes to the DB.
 764          * Should return true if unsure.
 765          *
 766          * @param string $sql
 767          * @return bool
 768          */
 769         protected function isWriteQuery( $sql ) {
 770                 return !preg_match(
 771                         '/^(?:SELECT|BEGIN|ROLLBACK|COMMIT|SET|SHOW|EXPLAIN|\(SELECT)\b/i', $sql );
 772         }
 773
 774         /**
 775          * @param $sql
 776          * @return string|null
 777          */
 778         protected function getQueryVerb( $sql ) {
 779                 return preg_match( '/^\s*([a-z]+)/i', $sql, $m ) ? strtoupper( $m[1] ) : null;
 780         }
 781
 782         /**
 783          * Determine whether a SQL statement is sensitive to isolation level.
 784          * A SQL statement is considered transactable if its result could vary
 785          * depending on the transaction isolation level. Operational commands
 786          * such as 'SET' and 'SHOW' are not considered to be transactable.
 787          *
 788          * @param string $sql
 789          * @return bool
 790          */
 791         protected function isTransactableQuery( $sql ) {
 792                 return !in_array(
 793                         $this->getQueryVerb( $sql ),
 794                         [ 'BEGIN', 'COMMIT', 'ROLLBACK', 'SHOW', 'SET', 'CREATE', 'ALTER' ],
 795                         true
 796                 );
 797         }
 798
 799         /**
 800          * @param string $sql A SQL query
 801          * @return bool Whether $sql is SQL for creating/dropping a new TEMPORARY table
 802          */
 803         protected function registerTempTableOperation( $sql ) {
 804                 if ( preg_match(
 805                         '/^CREATE\s+TEMPORARY\s+TABLE\s+(?:IF\s+NOT\s+EXISTS\s+)?[`"\']?(\w+)[`"\']?/i',
 806                         $sql,
 807                         $matches
 808                 ) ) {
 809                         $this->mSessionTempTables[$matches[1]] = 1;
 810
 811                         return true;
 812                 } elseif ( preg_match(
 813                         '/^DROP\s+(?:TEMPORARY\s+)?TABLE\s+(?:IF\s+EXISTS\s+)?[`"\']?(\w+)[`"\']?/i',
 814                         $sql,
 815                         $matches
 816                 ) ) {
 817                         unset( $this->mSessionTempTables[$matches[1]] );
 818
 819                         return true;
 820                 } elseif ( preg_match(
 821                         '/^(?:INSERT\s+(?:\w+\s+)?INTO|UPDATE|DELETE\s+FROM)\s+[`"\']?(\w+)[`"\']?/i',
 822                         $sql,
 823                         $matches
 824                 ) ) {
 825                         return isset( $this->mSessionTempTables[$matches[1]] );
 826                 }
 827
 828                 return false;
 829         }
 830
 831         public function query( $sql, $fname = __METHOD__, $tempIgnore = false ) {
 832                 $priorWritesPending = $this->writesOrCallbacksPending();
 833                 $this->mLastQuery = $sql;
 834
 835                 $isWrite = $this->isWriteQuery( $sql ) && !$this->registerTempTableOperation( $sql );
 836                 if ( $isWrite ) {
 837                         $reason = $this->getReadOnlyReason();
 838                         if ( $reason !== false ) {
 839                                 throw new DBReadOnlyError( $this, "Database is read-only: $reason" );
 840                         }
 841                         # Set a flag indicating that writes have been done
 842                         $this->mLastWriteTime = microtime( true );
 843                 }
 844
 845                 // Add trace comment to the begin of the sql string, right after the operator.
 846                 // Or, for one-word queries (like "BEGIN" or COMMIT") add it to the end (bug 42598)
 847                 $commentedSql = preg_replace( '/\s|$/', " /* $fname {$this->agent} */ ", $sql, 1 );
 848
 849                 # Start implicit transactions that wrap the request if DBO_TRX is enabled
 850                 if ( !$this->mTrxLevel && $this->getFlag( self::DBO_TRX )
 851                         && $this->isTransactableQuery( $sql )
 852                 ) {
 853                         $this->begin( __METHOD__ . " ($fname)", self::TRANSACTION_INTERNAL );
 854                         $this->mTrxAutomatic = true;
 855                 }
 856
 857                 # Keep track of whether the transaction has write queries pending
 858                 if ( $this->mTrxLevel && !$this->mTrxDoneWrites && $isWrite ) {
 859                         $this->mTrxDoneWrites = true;
 860                         $this->trxProfiler->transactionWritingIn(
 861                                 $this->mServer, $this->mDBname, $this->mTrxShortId );
 862                 }
 863
 864                 if ( $this->getFlag( self::DBO_DEBUG ) ) {
 865                         $this->queryLogger->debug( "{$this->mDBname} {$commentedSql}" );
 866                 }
 867
 868                 # Avoid fatals if close() was called
 869                 $this->assertOpen();
 870
 871                 # Send the query to the server
 872                 $ret = $this->doProfiledQuery( $sql, $commentedSql, $isWrite, $fname );
 873
 874                 # Try reconnecting if the connection was lost
 875                 if ( false === $ret && $this->wasErrorReissuable() ) {
 876                         $recoverable = $this->canRecoverFromDisconnect( $sql, $priorWritesPending );
 877                         # Stash the last error values before anything might clear them
 878                         $lastError = $this->lastError();
 879                         $lastErrno = $this->lastErrno();
 880                         # Update state tracking to reflect transaction loss due to disconnection
 881                         $this->handleSessionLoss();
 882                         if ( $this->reconnect() ) {
 883                                 $msg = __METHOD__ . ": lost connection to {$this->getServer()}; reconnected";
 884                                 $this->connLogger->warning( $msg );
 885                                 $this->queryLogger->warning(
 886                                         "$msg:\n" . ( new RuntimeException() )->getTraceAsString() );
 887
 888                                 if ( !$recoverable ) {
 889                                         # Callers may catch the exception and continue to use the DB
 890                                         $this->reportQueryError( $lastError, $lastErrno, $sql, $fname );
 891                                 } else {
 892                                         # Should be safe to silently retry the query
 893                                         $ret = $this->doProfiledQuery( $sql, $commentedSql, $isWrite, $fname );
 894                                 }
 895                         } else {
 896                                 $msg = __METHOD__ . ": lost connection to {$this->getServer()} permanently";
 897                                 $this->connLogger->error( $msg );
 898                         }
 899                 }
 900
 901                 if ( false === $ret ) {
 902                         # Deadlocks cause the entire transaction to abort, not just the statement.
 903                         # https://dev.mysql.com/doc/refman/5.7/en/innodb-error-handling.html
 904                         # https://www.postgresql.org/docs/9.1/static/explicit-locking.html
 905                         if ( $this->wasDeadlock() ) {
 906                                 if ( $this->explicitTrxActive() || $priorWritesPending ) {
 907                                         $tempIgnore = false; // not recoverable
 908                                 }
 909                                 # Update state tracking to reflect transaction loss
 910                                 $this->handleSessionLoss();
 911                         }
 912
 913                         $this->reportQueryError(
 914                                 $this->lastError(), $this->lastErrno(), $sql, $fname, $tempIgnore );
 915                 }
 916
 917                 $res = $this->resultObject( $ret );
 918
 919                 return $res;
 920         }
 921
 922         private function doProfiledQuery( $sql, $commentedSql, $isWrite, $fname ) {
 923                 // Update usage information for all active usage tracking sections
 924                 foreach ( $this->usageSectionInfo as $id => &$info ) {
 925                         if ( $isWrite ) {
 926                                 ++$info['writeQueries'];
 927                         } else {
 928                                 ++$info['readQueries'];
 929                         }
 930                         if ( $info['cacheSetOptions'] === null ) {
 931                                 $info['cacheSetOptions'] = self::getCacheSetOptions( $this );
 932                         }
 933                 }
 934                 unset( $info ); // destroy any reference
 935
 936                 $isMaster = !is_null( $this->getLBInfo( 'master' ) );
 937                 // generalizeSQL() will probably cut down the query to reasonable
 938                 // logging size most of the time. The substr is really just a sanity check.
 939                 if ( $isMaster ) {
 940                         $queryProf = 'query-m: ' . substr( self::generalizeSQL( $sql ), 0, 255 );
 941                 } else {
 942                         $queryProf = 'query: ' . substr( self::generalizeSQL( $sql ), 0, 255 );
 943                 }
 944
 945                 // Include query transaction state
 946                 $queryProf .= $this->mTrxShortId ? " [TRX#{$this->mTrxShortId}]" : "";
 947
 948                 $startTime = microtime( true );
 949                 if ( $this->profiler ) {
 950                         call_user_func( [ $this->profiler, 'profileIn' ], $queryProf );
 951                 }
 952                 $ret = $this->doQuery( $commentedSql );
 953                 if ( $this->profiler ) {
 954                         call_user_func( [ $this->profiler, 'profileOut' ], $queryProf );
 955                 }
 956                 $queryRuntime = max( microtime( true ) - $startTime, 0.0 );
 957
 958                 unset( $queryProfSection ); // profile out (if set)
 959
 960                 if ( $ret !== false ) {
 961                         $this->lastPing = $startTime;
 962                         if ( $isWrite && $this->mTrxLevel ) {
 963                                 $this->updateTrxWriteQueryTime( $sql, $queryRuntime );
 964                                 $this->mTrxWriteCallers[] = $fname;
 965                         }
 966                 }
 967
 968                 if ( $sql === self::PING_QUERY ) {
 969                         $this->mRTTEstimate = $queryRuntime;
 970                 }
 971
 972                 $this->trxProfiler->recordQueryCompletion(
 973                         $queryProf, $startTime, $isWrite, $this->affectedRows()
 974                 );
 975                 $this->queryLogger->debug( $sql, [
 976                         'method' => $fname,
 977                         'master' => $isMaster,
 978                         'runtime' => $queryRuntime,
 979                 ] );
 980
 981                 return $ret;
 982         }
 983
 984         /**
 985          * Update the estimated run-time of a query, not counting large row lock times
 986          *
 987          * LoadBalancer can be set to rollback transactions that will create huge replication
 988          * lag. It bases this estimate off of pendingWriteQueryDuration(). Certain simple
 989          * queries, like inserting a row can take a long time due to row locking. This method
 990          * uses some simple heuristics to discount those cases.
 991          *
 992          * @param string $sql A SQL write query
 993          * @param float $runtime Total runtime, including RTT
 994          */
 995         private function updateTrxWriteQueryTime( $sql, $runtime ) {
 996                 // Whether this is indicative of replica DB runtime (except for RBR or ws_repl)
 997                 $indicativeOfReplicaRuntime = true;
 998                 if ( $runtime > self::SLOW_WRITE_SEC ) {
 999                         $verb = $this->getQueryVerb( $sql );
1000                         // insert(), upsert(), replace() are fast unless bulky in size or blocked on locks
1001                         if ( $verb === 'INSERT' ) {
1002                                 $indicativeOfReplicaRuntime = $this->affectedRows() > self::SMALL_WRITE_ROWS;
1003                         } elseif ( $verb === 'REPLACE' ) {
1004                                 $indicativeOfReplicaRuntime = $this->affectedRows() > self::SMALL_WRITE_ROWS / 2;
1005                         }
1006                 }
1007
1008                 $this->mTrxWriteDuration += $runtime;
1009                 $this->mTrxWriteQueryCount += 1;
1010                 if ( $indicativeOfReplicaRuntime ) {
1011                         $this->mTrxWriteAdjDuration += $runtime;
1012                         $this->mTrxWriteAdjQueryCount += 1;
1013                 }
1014         }
1015
1016         private function canRecoverFromDisconnect( $sql, $priorWritesPending ) {
1017                 # Transaction dropped; this can mean lost writes, or REPEATABLE-READ snapshots.
1018                 # Dropped connections also mean that named locks are automatically released.
1019                 # Only allow error suppression in autocommit mode or when the lost transaction
1020                 # didn't matter anyway (aside from DBO_TRX snapshot loss).
1021                 if ( $this->mNamedLocksHeld ) {
1022                         return false; // possible critical section violation
1023                 } elseif ( $sql === 'COMMIT' ) {
1024                         return !$priorWritesPending; // nothing written anyway? (T127428)
1025                 } elseif ( $sql === 'ROLLBACK' ) {
1026                         return true; // transaction lost...which is also what was requested :)
1027                 } elseif ( $this->explicitTrxActive() ) {
1028                         return false; // don't drop atomocity
1029                 } elseif ( $priorWritesPending ) {
1030                         return false; // prior writes lost from implicit transaction
1031                 }
1032
1033                 return true;
1034         }
1035
1036         private function handleSessionLoss() {
1037                 $this->mTrxLevel = 0;
1038                 $this->mTrxIdleCallbacks = []; // bug 65263
1039                 $this->mTrxPreCommitCallbacks = []; // bug 65263
1040                 $this->mSessionTempTables = [];
1041                 $this->mNamedLocksHeld = [];
1042                 try {
1043                         // Handle callbacks in mTrxEndCallbacks
1044                         $this->runOnTransactionIdleCallbacks( self::TRIGGER_ROLLBACK );
1045                         $this->runTransactionListenerCallbacks( self::TRIGGER_ROLLBACK );
1046                         return null;
1047                 } catch ( Exception $e ) {
1048                         // Already logged; move on...
1049                         return $e;
1050                 }
1051         }
1052
1053         public function reportQueryError( $error, $errno, $sql, $fname, $tempIgnore = false ) {
1054                 if ( $this->ignoreErrors() || $tempIgnore ) {
1055                         $this->queryLogger->debug( "SQL ERROR (ignored): $error\n" );
1056                 } else {
1057                         $sql1line = mb_substr( str_replace( "\n", "\\n", $sql ), 0, 5 * 1024 );
1058                         $this->queryLogger->error(
1059                                 "{fname}\t{db_server}\t{errno}\t{error}\t{sql1line}",
1060                                 $this->getLogContext( [
1061                                         'method' => __METHOD__,
1062                                         'errno' => $errno,
1063                                         'error' => $error,
1064                                         'sql1line' => $sql1line,
1065                                         'fname' => $fname,
1066                                 ] )
1067                         );
1068                         $this->queryLogger->debug( "SQL ERROR: " . $error . "\n" );
1069                         throw new DBQueryError( $this, $error, $errno, $sql, $fname );
1070                 }
1071         }
1072
1073         public function freeResult( $res ) {
1074         }
1075
1076         public function selectField(
1077                 $table, $var, $cond = '', $fname = __METHOD__, $options = []
1078         ) {
1079                 if ( $var === '*' ) { // sanity
1080                         throw new DBUnexpectedError( $this, "Cannot use a * field: got '$var'" );
1081                 }
1082
1083                 if ( !is_array( $options ) ) {
1084                         $options = [ $options ];
1085                 }
1086
1087                 $options['LIMIT'] = 1;
1088
1089                 $res = $this->select( $table, $var, $cond, $fname, $options );
1090                 if ( $res === false || !$this->numRows( $res ) ) {
1091                         return false;
1092                 }
1093
1094                 $row = $this->fetchRow( $res );
1095
1096                 if ( $row !== false ) {
1097                         return reset( $row );
1098                 } else {
1099                         return false;
1100                 }
1101         }
1102
1103         public function selectFieldValues(
1104                 $table, $var, $cond = '', $fname = __METHOD__, $options = [], $join_conds = []
1105         ) {
1106                 if ( $var === '*' ) { // sanity
1107                         throw new DBUnexpectedError( $this, "Cannot use a * field" );
1108                 } elseif ( !is_string( $var ) ) { // sanity
1109                         throw new DBUnexpectedError( $this, "Cannot use an array of fields" );
1110                 }
1111
1112                 if ( !is_array( $options ) ) {
1113                         $options = [ $options ];
1114                 }
1115
1116                 $res = $this->select( $table, $var, $cond, $fname, $options, $join_conds );
1117                 if ( $res === false ) {
1118                         return false;
1119                 }
1120
1121                 $values = [];
1122                 foreach ( $res as $row ) {
1123                         $values[] = $row->$var;
1124                 }
1125
1126                 return $values;
1127         }
1128
1129         /**
1130          * Returns an optional USE INDEX clause to go after the table, and a
1131          * string to go at the end of the query.
1132          *
1133          * @param array $options Associative array of options to be turned into
1134          *   an SQL query, valid keys are listed in the function.
1135          * @return array
1136          * @see Database::select()
1137          */
1138         protected function makeSelectOptions( $options ) {
1139                 $preLimitTail = $postLimitTail = '';
1140                 $startOpts = '';
1141
1142                 $noKeyOptions = [];
1143
1144                 foreach ( $options as $key => $option ) {
1145                         if ( is_numeric( $key ) ) {
1146                                 $noKeyOptions[$option] = true;
1147                         }
1148                 }
1149
1150                 $preLimitTail .= $this->makeGroupByWithHaving( $options );
1151
1152                 $preLimitTail .= $this->makeOrderBy( $options );
1153
1154                 // if (isset($options['LIMIT'])) {
1155                 //      $tailOpts .= $this->limitResult('', $options['LIMIT'],
1156                 //              isset($options['OFFSET']) ? $options['OFFSET']
1157                 //              : false);
1158                 // }
1159
1160                 if ( isset( $noKeyOptions['FOR UPDATE'] ) ) {
1161                         $postLimitTail .= ' FOR UPDATE';
1162                 }
1163
1164                 if ( isset( $noKeyOptions['LOCK IN SHARE MODE'] ) ) {
1165                         $postLimitTail .= ' LOCK IN SHARE MODE';
1166                 }
1167
1168                 if ( isset( $noKeyOptions['DISTINCT'] ) || isset( $noKeyOptions['DISTINCTROW'] ) ) {
1169                         $startOpts .= 'DISTINCT';
1170                 }
1171
1172                 # Various MySQL extensions
1173                 if ( isset( $noKeyOptions['STRAIGHT_JOIN'] ) ) {
1174                         $startOpts .= ' /*! STRAIGHT_JOIN */';
1175                 }
1176
1177                 if ( isset( $noKeyOptions['HIGH_PRIORITY'] ) ) {
1178                         $startOpts .= ' HIGH_PRIORITY';
1179                 }
1180
1181                 if ( isset( $noKeyOptions['SQL_BIG_RESULT'] ) ) {
1182                         $startOpts .= ' SQL_BIG_RESULT';
1183                 }
1184
1185                 if ( isset( $noKeyOptions['SQL_BUFFER_RESULT'] ) ) {
1186                         $startOpts .= ' SQL_BUFFER_RESULT';
1187                 }
1188
1189                 if ( isset( $noKeyOptions['SQL_SMALL_RESULT'] ) ) {
1190                         $startOpts .= ' SQL_SMALL_RESULT';
1191                 }
1192
1193                 if ( isset( $noKeyOptions['SQL_CALC_FOUND_ROWS'] ) ) {
1194                         $startOpts .= ' SQL_CALC_FOUND_ROWS';
1195                 }
1196
1197                 if ( isset( $noKeyOptions['SQL_CACHE'] ) ) {
1198                         $startOpts .= ' SQL_CACHE';
1199                 }
1200
1201                 if ( isset( $noKeyOptions['SQL_NO_CACHE'] ) ) {
1202                         $startOpts .= ' SQL_NO_CACHE';
1203                 }
1204
1205                 if ( isset( $options['USE INDEX'] ) && is_string( $options['USE INDEX'] ) ) {
1206                         $useIndex = $this->useIndexClause( $options['USE INDEX'] );
1207                 } else {
1208                         $useIndex = '';
1209                 }
1210                 if ( isset( $options['IGNORE INDEX'] ) && is_string( $options['IGNORE INDEX'] ) ) {
1211                         $ignoreIndex = $this->ignoreIndexClause( $options['IGNORE INDEX'] );
1212                 } else {
1213                         $ignoreIndex = '';
1214                 }
1215
1216                 return [ $startOpts, $useIndex, $preLimitTail, $postLimitTail, $ignoreIndex ];
1217         }
1218
1219         /**
1220          * Returns an optional GROUP BY with an optional HAVING
1221          *
1222          * @param array $options Associative array of options
1223          * @return string
1224          * @see Database::select()
1225          * @since 1.21
1226          */
1227         protected function makeGroupByWithHaving( $options ) {
1228                 $sql = '';
1229                 if ( isset( $options['GROUP BY'] ) ) {
1230                         $gb = is_array( $options['GROUP BY'] )
1231                                 ? implode( ',', $options['GROUP BY'] )
1232                                 : $options['GROUP BY'];
1233                         $sql .= ' GROUP BY ' . $gb;
1234                 }
1235                 if ( isset( $options['HAVING'] ) ) {
1236                         $having = is_array( $options['HAVING'] )
1237                                 ? $this->makeList( $options['HAVING'], self::LIST_AND )
1238                                 : $options['HAVING'];
1239                         $sql .= ' HAVING ' . $having;
1240                 }
1241
1242                 return $sql;
1243         }
1244
1245         /**
1246          * Returns an optional ORDER BY
1247          *
1248          * @param array $options Associative array of options
1249          * @return string
1250          * @see Database::select()
1251          * @since 1.21
1252          */
1253         protected function makeOrderBy( $options ) {
1254                 if ( isset( $options['ORDER BY'] ) ) {
1255                         $ob = is_array( $options['ORDER BY'] )
1256                                 ? implode( ',', $options['ORDER BY'] )
1257                                 : $options['ORDER BY'];
1258
1259                         return ' ORDER BY ' . $ob;
1260                 }
1261
1262                 return '';
1263         }
1264
1265         public function select( $table, $vars, $conds = '', $fname = __METHOD__,
1266                 $options = [], $join_conds = [] ) {
1267                 $sql = $this->selectSQLText( $table, $vars, $conds, $fname, $options, $join_conds );
1268
1269                 return $this->query( $sql, $fname );
1270         }
1271
1272         public function selectSQLText( $table, $vars, $conds = '', $fname = __METHOD__,
1273                 $options = [], $join_conds = []
1274         ) {
1275                 if ( is_array( $vars ) ) {
1276                         $vars = implode( ',', $this->fieldNamesWithAlias( $vars ) );
1277                 }
1278
1279                 $options = (array)$options;
1280                 $useIndexes = ( isset( $options['USE INDEX'] ) && is_array( $options['USE INDEX'] ) )
1281                         ? $options['USE INDEX']
1282                         : [];
1283                 $ignoreIndexes = (
1284                         isset( $options['IGNORE INDEX'] ) &&
1285                         is_array( $options['IGNORE INDEX'] )
1286                 )
1287                         ? $options['IGNORE INDEX']
1288                         : [];
1289
1290                 if ( is_array( $table ) ) {
1291                         $from = ' FROM ' .
1292                                 $this->tableNamesWithIndexClauseOrJOIN(
1293                                         $table, $useIndexes, $ignoreIndexes, $join_conds );
1294                 } elseif ( $table != '' ) {
1295                         if ( $table[0] == ' ' ) {
1296                                 $from = ' FROM ' . $table;
1297                         } else {
1298                                 $from = ' FROM ' .
1299                                         $this->tableNamesWithIndexClauseOrJOIN(
1300                                                 [ $table ], $useIndexes, $ignoreIndexes, [] );
1301                         }
1302                 } else {
1303                         $from = '';
1304                 }
1305
1306                 list( $startOpts, $useIndex, $preLimitTail, $postLimitTail, $ignoreIndex ) =
1307                         $this->makeSelectOptions( $options );
1308
1309                 if ( !empty( $conds ) ) {
1310                         if ( is_array( $conds ) ) {
1311                                 $conds = $this->makeList( $conds, self::LIST_AND );
1312                         }
1313                         $sql = "SELECT $startOpts $vars $from $useIndex $ignoreIndex " .
1314                                 "WHERE $conds $preLimitTail";
1315                 } else {
1316                         $sql = "SELECT $startOpts $vars $from $useIndex $ignoreIndex $preLimitTail";
1317                 }
1318
1319                 if ( isset( $options['LIMIT'] ) ) {
1320                         $sql = $this->limitResult( $sql, $options['LIMIT'],
1321                                 isset( $options['OFFSET'] ) ? $options['OFFSET'] : false );
1322                 }
1323                 $sql = "$sql $postLimitTail";
1324
1325                 if ( isset( $options['EXPLAIN'] ) ) {
1326                         $sql = 'EXPLAIN ' . $sql;
1327                 }
1328
1329                 return $sql;
1330         }
1331
1332         public function selectRow( $table, $vars, $conds, $fname = __METHOD__,
1333                 $options = [], $join_conds = []
1334         ) {
1335                 $options = (array)$options;
1336                 $options['LIMIT'] = 1;
1337                 $res = $this->select( $table, $vars, $conds, $fname, $options, $join_conds );
1338
1339                 if ( $res === false ) {
1340                         return false;
1341                 }
1342
1343                 if ( !$this->numRows( $res ) ) {
1344                         return false;
1345                 }
1346
1347                 $obj = $this->fetchObject( $res );
1348
1349                 return $obj;
1350         }
1351
1352         public function estimateRowCount(
1353                 $table, $vars = '*', $conds = '', $fname = __METHOD__, $options = []
1354         ) {
1355                 $rows = 0;
1356                 $res = $this->select( $table, [ 'rowcount' => 'COUNT(*)' ], $conds, $fname, $options );
1357
1358                 if ( $res ) {
1359                         $row = $this->fetchRow( $res );
1360                         $rows = ( isset( $row['rowcount'] ) ) ? (int)$row['rowcount'] : 0;
1361                 }
1362
1363                 return $rows;
1364         }
1365
1366         public function selectRowCount(
1367                 $tables, $vars = '*', $conds = '', $fname = __METHOD__, $options = [], $join_conds = []
1368         ) {
1369                 $rows = 0;
1370                 $sql = $this->selectSQLText( $tables, '1', $conds, $fname, $options, $join_conds );
1371                 $res = $this->query( "SELECT COUNT(*) AS rowcount FROM ($sql) tmp_count", $fname );
1372
1373                 if ( $res ) {
1374                         $row = $this->fetchRow( $res );
1375                         $rows = ( isset( $row['rowcount'] ) ) ? (int)$row['rowcount'] : 0;
1376                 }
1377
1378                 return $rows;
1379         }
1380
1381         /**
1382          * Removes most variables from an SQL query and replaces them with X or N for numbers.
1383          * It's only slightly flawed. Don't use for anything important.
1384          *
1385          * @param string $sql A SQL Query
1386          *
1387          * @return string
1388          */
1389         protected static function generalizeSQL( $sql ) {
1390                 # This does the same as the regexp below would do, but in such a way
1391                 # as to avoid crashing php on some large strings.
1392                 # $sql = preg_replace( "/'([^\\\\']|\\\\.)*'|\"([^\\\\\"]|\\\\.)*\"/", "'X'", $sql );
1393
1394                 $sql = str_replace( "\\\\", '', $sql );
1395                 $sql = str_replace( "\\'", '', $sql );
1396                 $sql = str_replace( "\\\"", '', $sql );
1397                 $sql = preg_replace( "/'.*'/s", "'X'", $sql );
1398                 $sql = preg_replace( '/".*"/s', "'X'", $sql );
1399
1400                 # All newlines, tabs, etc replaced by single space
1401                 $sql = preg_replace( '/\s+/', ' ', $sql );
1402
1403                 # All numbers => N,
1404                 # except the ones surrounded by characters, e.g. l10n
1405                 $sql = preg_replace( '/-?\d+(,-?\d+)+/s', 'N,...,N', $sql );
1406                 $sql = preg_replace( '/(?<![a-zA-Z])-?\d+(?![a-zA-Z])/s', 'N', $sql );
1407
1408                 return $sql;
1409         }
1410
1411         public function fieldExists( $table, $field, $fname = __METHOD__ ) {
1412                 $info = $this->fieldInfo( $table, $field );
1413
1414                 return (bool)$info;
1415         }
1416
1417         public function indexExists( $table, $index, $fname = __METHOD__ ) {
1418                 if ( !$this->tableExists( $table ) ) {
1419                         return null;
1420                 }
1421
1422                 $info = $this->indexInfo( $table, $index, $fname );
1423                 if ( is_null( $info ) ) {
1424                         return null;
1425                 } else {
1426                         return $info !== false;
1427                 }
1428         }
1429
1430         public function tableExists( $table, $fname = __METHOD__ ) {
1431                 $tableRaw = $this->tableName( $table, 'raw' );
1432                 if ( isset( $this->mSessionTempTables[$tableRaw] ) ) {
1433                         return true; // already known to exist
1434                 }
1435
1436                 $table = $this->tableName( $table );
1437                 $old = $this->ignoreErrors( true );
1438                 $res = $this->query( "SELECT 1 FROM $table LIMIT 1", $fname );
1439                 $this->ignoreErrors( $old );
1440
1441                 return (bool)$res;
1442         }
1443
1444         public function indexUnique( $table, $index ) {
1445                 $indexInfo = $this->indexInfo( $table, $index );
1446
1447                 if ( !$indexInfo ) {
1448                         return null;
1449                 }
1450
1451                 return !$indexInfo[0]->Non_unique;
1452         }
1453
1454         /**
1455          * Helper for Database::insert().
1456          *
1457          * @param array $options
1458          * @return string
1459          */
1460         protected function makeInsertOptions( $options ) {
1461                 return implode( ' ', $options );
1462         }
1463
1464         public function insert( $table, $a, $fname = __METHOD__, $options = [] ) {
1465                 # No rows to insert, easy just return now
1466                 if ( !count( $a ) ) {
1467                         return true;
1468                 }
1469
1470                 $table = $this->tableName( $table );
1471
1472                 if ( !is_array( $options ) ) {
1473                         $options = [ $options ];
1474                 }
1475
1476                 $fh = null;
1477                 if ( isset( $options['fileHandle'] ) ) {
1478                         $fh = $options['fileHandle'];
1479                 }
1480                 $options = $this->makeInsertOptions( $options );
1481
1482                 if ( isset( $a[0] ) && is_array( $a[0] ) ) {
1483                         $multi = true;
1484                         $keys = array_keys( $a[0] );
1485                 } else {
1486                         $multi = false;
1487                         $keys = array_keys( $a );
1488                 }
1489
1490                 $sql = 'INSERT ' . $options .
1491                         " INTO $table (" . implode( ',', $keys ) . ') VALUES ';
1492
1493                 if ( $multi ) {
1494                         $first = true;
1495                         foreach ( $a as $row ) {
1496                                 if ( $first ) {
1497                                         $first = false;
1498                                 } else {
1499                                         $sql .= ',';
1500                                 }
1501                                 $sql .= '(' . $this->makeList( $row ) . ')';
1502                         }
1503                 } else {
1504                         $sql .= '(' . $this->makeList( $a ) . ')';
1505                 }
1506
1507                 if ( $fh !== null && false === fwrite( $fh, $sql ) ) {
1508                         return false;
1509                 } elseif ( $fh !== null ) {
1510                         return true;
1511                 }
1512
1513                 return (bool)$this->query( $sql, $fname );
1514         }
1515
1516         /**
1517          * Make UPDATE options array for Database::makeUpdateOptions
1518          *
1519          * @param array $options
1520          * @return array
1521          */
1522         protected function makeUpdateOptionsArray( $options ) {
1523                 if ( !is_array( $options ) ) {
1524                         $options = [ $options ];
1525                 }
1526
1527                 $opts = [];
1528
1529                 if ( in_array( 'IGNORE', $options ) ) {
1530                         $opts[] = 'IGNORE';
1531                 }
1532
1533                 return $opts;
1534         }
1535
1536         /**
1537          * Make UPDATE options for the Database::update function
1538          *
1539          * @param array $options The options passed to Database::update
1540          * @return string
1541          */
1542         protected function makeUpdateOptions( $options ) {
1543                 $opts = $this->makeUpdateOptionsArray( $options );
1544
1545                 return implode( ' ', $opts );
1546         }
1547
1548         public function update( $table, $values, $conds, $fname = __METHOD__, $options = [] ) {
1549                 $table = $this->tableName( $table );
1550                 $opts = $this->makeUpdateOptions( $options );
1551                 $sql = "UPDATE $opts $table SET " . $this->makeList( $values, self::LIST_SET );
1552
1553                 if ( $conds !== [] && $conds !== '*' ) {
1554                         $sql .= " WHERE " . $this->makeList( $conds, self::LIST_AND );
1555                 }
1556
1557                 return $this->query( $sql, $fname );
1558         }
1559
1560         public function makeList( $a, $mode = self::LIST_COMMA ) {
1561                 if ( !is_array( $a ) ) {
1562                         throw new DBUnexpectedError( $this, __METHOD__ . ' called with incorrect parameters' );
1563                 }
1564
1565                 $first = true;
1566                 $list = '';
1567
1568                 foreach ( $a as $field => $value ) {
1569                         if ( !$first ) {
1570                                 if ( $mode == self::LIST_AND ) {
1571                                         $list .= ' AND ';
1572                                 } elseif ( $mode == self::LIST_OR ) {
1573                                         $list .= ' OR ';
1574                                 } else {
1575                                         $list .= ',';
1576                                 }
1577                         } else {
1578                                 $first = false;
1579                         }
1580
1581                         if ( ( $mode == self::LIST_AND || $mode == self::LIST_OR ) && is_numeric( $field ) ) {
1582                                 $list .= "($value)";
1583                         } elseif ( $mode == self::LIST_SET && is_numeric( $field ) ) {
1584                                 $list .= "$value";
1585                         } elseif (
1586                                 ( $mode == self::LIST_AND || $mode == self::LIST_OR ) && is_array( $value )
1587                         ) {
1588                                 // Remove null from array to be handled separately if found
1589                                 $includeNull = false;
1590                                 foreach ( array_keys( $value, null, true ) as $nullKey ) {
1591                                         $includeNull = true;
1592                                         unset( $value[$nullKey] );
1593                                 }
1594                                 if ( count( $value ) == 0 && !$includeNull ) {
1595                                         throw new InvalidArgumentException(
1596                                                 __METHOD__ . ": empty input for field $field" );
1597                                 } elseif ( count( $value ) == 0 ) {
1598                                         // only check if $field is null
1599                                         $list .= "$field IS NULL";
1600                                 } else {
1601                                         // IN clause contains at least one valid element
1602                                         if ( $includeNull ) {
1603                                                 // Group subconditions to ensure correct precedence
1604                                                 $list .= '(';
1605                                         }
1606                                         if ( count( $value ) == 1 ) {
1607                                                 // Special-case single values, as IN isn't terribly efficient
1608                                                 // Don't necessarily assume the single key is 0; we don't
1609                                                 // enforce linear numeric ordering on other arrays here.
1610                                                 $value = array_values( $value )[0];
1611                                                 $list .= $field . " = " . $this->addQuotes( $value );
1612                                         } else {
1613                                                 $list .= $field . " IN (" . $this->makeList( $value ) . ") ";
1614                                         }
1615                                         // if null present in array, append IS NULL
1616                                         if ( $includeNull ) {
1617                                                 $list .= " OR $field IS NULL)";
1618                                         }
1619                                 }
1620                         } elseif ( $value === null ) {
1621                                 if ( $mode == self::LIST_AND || $mode == self::LIST_OR ) {
1622                                         $list .= "$field IS ";
1623                                 } elseif ( $mode == self::LIST_SET ) {
1624                                         $list .= "$field = ";
1625                                 }
1626                                 $list .= 'NULL';
1627                         } else {
1628                                 if (
1629                                         $mode == self::LIST_AND || $mode == self::LIST_OR || $mode == self::LIST_SET
1630                                 ) {
1631                                         $list .= "$field = ";
1632                                 }
1633                                 $list .= $mode == self::LIST_NAMES ? $value : $this->addQuotes( $value );
1634                         }
1635                 }
1636
1637                 return $list;
1638         }
1639
1640         public function makeWhereFrom2d( $data, $baseKey, $subKey ) {
1641                 $conds = [];
1642
1643                 foreach ( $data as $base => $sub ) {
1644                         if ( count( $sub ) ) {
1645                                 $conds[] = $this->makeList(
1646                                         [ $baseKey => $base, $subKey => array_keys( $sub ) ],
1647                                         self::LIST_AND );
1648                         }
1649                 }
1650
1651                 if ( $conds ) {
1652                         return $this->makeList( $conds, self::LIST_OR );
1653                 } else {
1654                         // Nothing to search for...
1655                         return false;
1656                 }
1657         }
1658
1659         public function aggregateValue( $valuedata, $valuename = 'value' ) {
1660                 return $valuename;
1661         }
1662
1663         public function bitNot( $field ) {
1664                 return "(~$field)";
1665         }
1666
1667         public function bitAnd( $fieldLeft, $fieldRight ) {
1668                 return "($fieldLeft & $fieldRight)";
1669         }
1670
1671         public function bitOr( $fieldLeft, $fieldRight ) {
1672                 return "($fieldLeft | $fieldRight)";
1673         }
1674
1675         public function buildConcat( $stringList ) {
1676                 return 'CONCAT(' . implode( ',', $stringList ) . ')';
1677         }
1678
1679         public function buildGroupConcatField(
1680                 $delim, $table, $field, $conds = '', $join_conds = []
1681         ) {
1682                 $fld = "GROUP_CONCAT($field SEPARATOR " . $this->addQuotes( $delim ) . ')';
1683
1684                 return '(' . $this->selectSQLText( $table, $fld, $conds, null, [], $join_conds ) . ')';
1685         }
1686
1687         public function buildStringCast( $field ) {
1688                 return $field;
1689         }
1690
1691         public function selectDB( $db ) {
1692                 # Stub. Shouldn't cause serious problems if it's not overridden, but
1693                 # if your database engine supports a concept similar to MySQL's
1694                 # databases you may as well.
1695                 $this->mDBname = $db;
1696
1697                 return true;
1698         }
1699
1700         public function getDBname() {
1701                 return $this->mDBname;
1702         }
1703
1704         public function getServer() {
1705                 return $this->mServer;
1706         }
1707
1708         public function tableName( $name, $format = 'quoted' ) {
1709                 # Skip the entire process when we have a string quoted on both ends.
1710                 # Note that we check the end so that we will still quote any use of
1711                 # use of `database`.table. But won't break things if someone wants
1712                 # to query a database table with a dot in the name.
1713                 if ( $this->isQuotedIdentifier( $name ) ) {
1714                         return $name;
1715                 }
1716
1717                 # Lets test for any bits of text that should never show up in a table
1718                 # name. Basically anything like JOIN or ON which are actually part of
1719                 # SQL queries, but may end up inside of the table value to combine
1720                 # sql. Such as how the API is doing.
1721                 # Note that we use a whitespace test rather than a \b test to avoid
1722                 # any remote case where a word like on may be inside of a table name
1723                 # surrounded by symbols which may be considered word breaks.
1724                 if ( preg_match( '/(^|\s)(DISTINCT|JOIN|ON|AS)(\s|$)/i', $name ) !== 0 ) {
1725                         return $name;
1726                 }
1727
1728                 # Split database and table into proper variables.
1729                 # We reverse the explode so that database.table and table both output
1730                 # the correct table.
1731                 $dbDetails = explode( '.', $name, 3 );
1732                 if ( count( $dbDetails ) == 3 ) {
1733                         list( $database, $schema, $table ) = $dbDetails;
1734                         # We don't want any prefix added in this case
1735                         $prefix = '';
1736                 } elseif ( count( $dbDetails ) == 2 ) {
1737                         list( $database, $table ) = $dbDetails;
1738                         # We don't want any prefix added in this case
1739                         $prefix = '';
1740                         # In dbs that support it, $database may actually be the schema
1741                         # but that doesn't affect any of the functionality here
1742                         $schema = '';
1743                 } else {
1744                         list( $table ) = $dbDetails;
1745                         if ( isset( $this->tableAliases[$table] ) ) {
1746                                 $database = $this->tableAliases[$table]['dbname'];
1747                                 $schema = is_string( $this->tableAliases[$table]['schema'] )
1748                                         ? $this->tableAliases[$table]['schema']
1749                                         : $this->mSchema;
1750                                 $prefix = is_string( $this->tableAliases[$table]['prefix'] )
1751                                         ? $this->tableAliases[$table]['prefix']
1752                                         : $this->mTablePrefix;
1753                         } else {
1754                                 $database = '';
1755                                 $schema = $this->mSchema; # Default schema
1756                                 $prefix = $this->mTablePrefix; # Default prefix
1757                         }
1758                 }
1759
1760                 # Quote $table and apply the prefix if not quoted.
1761                 # $tableName might be empty if this is called from Database::replaceVars()
1762                 $tableName = "{$prefix}{$table}";
1763                 if ( $format === 'quoted'
1764                         && !$this->isQuotedIdentifier( $tableName )
1765                         && $tableName !== ''
1766                 ) {
1767                         $tableName = $this->addIdentifierQuotes( $tableName );
1768                 }
1769
1770                 # Quote $schema and $database and merge them with the table name if needed
1771                 $tableName = $this->prependDatabaseOrSchema( $schema, $tableName, $format );
1772                 $tableName = $this->prependDatabaseOrSchema( $database, $tableName, $format );
1773
1774                 return $tableName;
1775         }
1776
1777         /**
1778          * @param string|null $namespace Database or schema
1779          * @param string $relation Name of table, view, sequence, etc...
1780          * @param string $format One of (raw, quoted)
1781          * @return string Relation name with quoted and merged $namespace as needed
1782          */
1783         private function prependDatabaseOrSchema( $namespace, $relation, $format ) {
1784                 if ( strlen( $namespace ) ) {
1785                         if ( $format === 'quoted' && !$this->isQuotedIdentifier( $namespace ) ) {
1786                                 $namespace = $this->addIdentifierQuotes( $namespace );
1787                         }
1788                         $relation = $namespace . '.' . $relation;
1789                 }
1790
1791                 return $relation;
1792         }
1793
1794         public function tableNames() {
1795                 $inArray = func_get_args();
1796                 $retVal = [];
1797
1798                 foreach ( $inArray as $name ) {
1799                         $retVal[$name] = $this->tableName( $name );
1800                 }
1801
1802                 return $retVal;
1803         }
1804
1805         public function tableNamesN() {
1806                 $inArray = func_get_args();
1807                 $retVal = [];
1808
1809                 foreach ( $inArray as $name ) {
1810                         $retVal[] = $this->tableName( $name );
1811                 }
1812
1813                 return $retVal;
1814         }
1815
1816         /**
1817          * Get an aliased table name
1818          * e.g. tableName AS newTableName
1819          *
1820          * @param string $name Table name, see tableName()
1821          * @param string|bool $alias Alias (optional)
1822          * @return string SQL name for aliased table. Will not alias a table to its own name
1823          */
1824         protected function tableNameWithAlias( $name, $alias = false ) {
1825                 if ( !$alias || $alias == $name ) {
1826                         return $this->tableName( $name );
1827                 } else {
1828                         return $this->tableName( $name ) . ' ' . $this->addIdentifierQuotes( $alias );
1829                 }
1830         }
1831
1832         /**
1833          * Gets an array of aliased table names
1834          *
1835          * @param array $tables [ [alias] => table ]
1836          * @return string[] See tableNameWithAlias()
1837          */
1838         protected function tableNamesWithAlias( $tables ) {
1839                 $retval = [];
1840                 foreach ( $tables as $alias => $table ) {
1841                         if ( is_numeric( $alias ) ) {
1842                                 $alias = $table;
1843                         }
1844                         $retval[] = $this->tableNameWithAlias( $table, $alias );
1845                 }
1846
1847                 return $retval;
1848         }
1849
1850         /**
1851          * Get an aliased field name
1852          * e.g. fieldName AS newFieldName
1853          *
1854          * @param string $name Field name
1855          * @param string|bool $alias Alias (optional)
1856          * @return string SQL name for aliased field. Will not alias a field to its own name
1857          */
1858         protected function fieldNameWithAlias( $name, $alias = false ) {
1859                 if ( !$alias || (string)$alias === (string)$name ) {
1860                         return $name;
1861                 } else {
1862                         return $name . ' AS ' . $this->addIdentifierQuotes( $alias ); // PostgreSQL needs AS
1863                 }
1864         }
1865
1866         /**
1867          * Gets an array of aliased field names
1868          *
1869          * @param array $fields [ [alias] => field ]
1870          * @return string[] See fieldNameWithAlias()
1871          */
1872         protected function fieldNamesWithAlias( $fields ) {
1873                 $retval = [];
1874                 foreach ( $fields as $alias => $field ) {
1875                         if ( is_numeric( $alias ) ) {
1876                                 $alias = $field;
1877                         }
1878                         $retval[] = $this->fieldNameWithAlias( $field, $alias );
1879                 }
1880
1881                 return $retval;
1882         }
1883
1884         /**
1885          * Get the aliased table name clause for a FROM clause
1886          * which might have a JOIN and/or USE INDEX or IGNORE INDEX clause
1887          *
1888          * @param array $tables ( [alias] => table )
1889          * @param array $use_index Same as for select()
1890          * @param array $ignore_index Same as for select()
1891          * @param array $join_conds Same as for select()
1892          * @return string
1893          */
1894         protected function tableNamesWithIndexClauseOrJOIN(
1895                 $tables, $use_index = [], $ignore_index = [], $join_conds = []
1896         ) {
1897                 $ret = [];
1898                 $retJOIN = [];
1899                 $use_index = (array)$use_index;
1900                 $ignore_index = (array)$ignore_index;
1901                 $join_conds = (array)$join_conds;
1902
1903                 foreach ( $tables as $alias => $table ) {
1904                         if ( !is_string( $alias ) ) {
1905                                 // No alias? Set it equal to the table name
1906                                 $alias = $table;
1907                         }
1908                         // Is there a JOIN clause for this table?
1909                         if ( isset( $join_conds[$alias] ) ) {
1910                                 list( $joinType, $conds ) = $join_conds[$alias];
1911                                 $tableClause = $joinType;
1912                                 $tableClause .= ' ' . $this->tableNameWithAlias( $table, $alias );
1913                                 if ( isset( $use_index[$alias] ) ) { // has USE INDEX?
1914                                         $use = $this->useIndexClause( implode( ',', (array)$use_index[$alias] ) );
1915                                         if ( $use != '' ) {
1916                                                 $tableClause .= ' ' . $use;
1917                                         }
1918                                 }
1919                                 if ( isset( $ignore_index[$alias] ) ) { // has IGNORE INDEX?
1920                                         $ignore = $this->ignoreIndexClause(
1921                                                 implode( ',', (array)$ignore_index[$alias] ) );
1922                                         if ( $ignore != '' ) {
1923                                                 $tableClause .= ' ' . $ignore;
1924                                         }
1925                                 }
1926                                 $on = $this->makeList( (array)$conds, self::LIST_AND );
1927                                 if ( $on != '' ) {
1928                                         $tableClause .= ' ON (' . $on . ')';
1929                                 }
1930
1931                                 $retJOIN[] = $tableClause;
1932                         } elseif ( isset( $use_index[$alias] ) ) {
1933                                 // Is there an INDEX clause for this table?
1934                                 $tableClause = $this->tableNameWithAlias( $table, $alias );
1935                                 $tableClause .= ' ' . $this->useIndexClause(
1936                                                 implode( ',', (array)$use_index[$alias] )
1937                                         );
1938
1939                                 $ret[] = $tableClause;
1940                         } elseif ( isset( $ignore_index[$alias] ) ) {
1941                                 // Is there an INDEX clause for this table?
1942                                 $tableClause = $this->tableNameWithAlias( $table, $alias );
1943                                 $tableClause .= ' ' . $this->ignoreIndexClause(
1944                                                 implode( ',', (array)$ignore_index[$alias] )
1945                                         );
1946
1947                                 $ret[] = $tableClause;
1948                         } else {
1949                                 $tableClause = $this->tableNameWithAlias( $table, $alias );
1950
1951                                 $ret[] = $tableClause;
1952                         }
1953                 }
1954
1955                 // We can't separate explicit JOIN clauses with ',', use ' ' for those
1956                 $implicitJoins = !empty( $ret ) ? implode( ',', $ret ) : "";
1957                 $explicitJoins = !empty( $retJOIN ) ? implode( ' ', $retJOIN ) : "";
1958
1959                 // Compile our final table clause
1960                 return implode( ' ', [ $implicitJoins, $explicitJoins ] );
1961         }
1962
1963         /**
1964          * Get the name of an index in a given table.
1965          *
1966          * @param string $index
1967          * @return string
1968          */
1969         protected function indexName( $index ) {
1970                 return $index;
1971         }
1972
1973         public function addQuotes( $s ) {
1974                 if ( $s instanceof Blob ) {
1975                         $s = $s->fetch();
1976                 }
1977                 if ( $s === null ) {
1978                         return 'NULL';
1979                 } elseif ( is_bool( $s ) ) {
1980                         return (int)$s;
1981                 } else {
1982                         # This will also quote numeric values. This should be harmless,
1983                         # and protects against weird problems that occur when they really
1984                         # _are_ strings such as article titles and string->number->string
1985                         # conversion is not 1:1.
1986                         return "'" . $this->strencode( $s ) . "'";
1987                 }
1988         }
1989
1990         /**
1991          * Quotes an identifier using `backticks` or "double quotes" depending on the database type.
1992          * MySQL uses `backticks` while basically everything else uses double quotes.
1993          * Since MySQL is the odd one out here the double quotes are our generic
1994          * and we implement backticks in DatabaseMysql.
1995          *
1996          * @param string $s
1997          * @return string
1998          */
1999         public function addIdentifierQuotes( $s ) {
2000                 return '"' . str_replace( '"', '""', $s ) . '"';
2001         }
2002
2003         /**
2004          * Returns if the given identifier looks quoted or not according to
2005          * the database convention for quoting identifiers .
2006          *
2007          * @note Do not use this to determine if untrusted input is safe.
2008          *   A malicious user can trick this function.
2009          * @param string $name
2010          * @return bool
2011          */
2012         public function isQuotedIdentifier( $name ) {
2013                 return $name[0] == '"' && substr( $name, -1, 1 ) == '"';
2014         }
2015
2016         /**
2017          * @param string $s
2018          * @return string
2019          */
2020         protected function escapeLikeInternal( $s ) {
2021                 return addcslashes( $s, '\%_' );
2022         }
2023
2024         public function buildLike() {
2025                 $params = func_get_args();
2026
2027                 if ( count( $params ) > 0 && is_array( $params[0] ) ) {
2028                         $params = $params[0];
2029                 }
2030
2031                 $s = '';
2032
2033                 foreach ( $params as $value ) {
2034                         if ( $value instanceof LikeMatch ) {
2035                                 $s .= $value->toString();
2036                         } else {
2037                                 $s .= $this->escapeLikeInternal( $value );
2038                         }
2039                 }
2040
2041                 return " LIKE {$this->addQuotes( $s )} ";
2042         }
2043
2044         public function anyChar() {
2045                 return new LikeMatch( '_' );
2046         }
2047
2048         public function anyString() {
2049                 return new LikeMatch( '%' );
2050         }
2051
2052         public function nextSequenceValue( $seqName ) {
2053                 return null;
2054         }
2055
2056         /**
2057          * USE INDEX clause. Unlikely to be useful for anything but MySQL. This
2058          * is only needed because a) MySQL must be as efficient as possible due to
2059          * its use on Wikipedia, and b) MySQL 4.0 is kind of dumb sometimes about
2060          * which index to pick. Anyway, other databases might have different
2061          * indexes on a given table. So don't bother overriding this unless you're
2062          * MySQL.
2063          * @param string $index
2064          * @return string
2065          */
2066         public function useIndexClause( $index ) {
2067                 return '';
2068         }
2069
2070         /**
2071          * IGNORE INDEX clause. Unlikely to be useful for anything but MySQL. This
2072          * is only needed because a) MySQL must be as efficient as possible due to
2073          * its use on Wikipedia, and b) MySQL 4.0 is kind of dumb sometimes about
2074          * which index to pick. Anyway, other databases might have different
2075          * indexes on a given table. So don't bother overriding this unless you're
2076          * MySQL.
2077          * @param string $index
2078          * @return string
2079          */
2080         public function ignoreIndexClause( $index ) {
2081                 return '';
2082         }
2083
2084         public function replace( $table, $uniqueIndexes, $rows, $fname = __METHOD__ ) {
2085                 $quotedTable = $this->tableName( $table );
2086
2087                 if ( count( $rows ) == 0 ) {
2088                         return;
2089                 }
2090
2091                 # Single row case
2092                 if ( !is_array( reset( $rows ) ) ) {
2093                         $rows = [ $rows ];
2094                 }
2095
2096                 // @FXIME: this is not atomic, but a trx would break affectedRows()
2097                 foreach ( $rows as $row ) {
2098                         # Delete rows which collide
2099                         if ( $uniqueIndexes ) {
2100                                 $sql = "DELETE FROM $quotedTable WHERE ";
2101                                 $first = true;
2102                                 foreach ( $uniqueIndexes as $index ) {
2103                                         if ( $first ) {
2104                                                 $first = false;
2105                                                 $sql .= '( ';
2106                                         } else {
2107                                                 $sql .= ' ) OR ( ';
2108                                         }
2109                                         if ( is_array( $index ) ) {
2110                                                 $first2 = true;
2111                                                 foreach ( $index as $col ) {
2112                                                         if ( $first2 ) {
2113                                                                 $first2 = false;
2114                                                         } else {
2115                                                                 $sql .= ' AND ';
2116                                                         }
2117                                                         $sql .= $col . '=' . $this->addQuotes( $row[$col] );
2118                                                 }
2119                                         } else {
2120                                                 $sql .= $index . '=' . $this->addQuotes( $row[$index] );
2121                                         }
2122                                 }
2123                                 $sql .= ' )';
2124                                 $this->query( $sql, $fname );
2125                         }
2126
2127                         # Now insert the row
2128                         $this->insert( $table, $row, $fname );
2129                 }
2130         }
2131
2132         /**
2133          * REPLACE query wrapper for MySQL and SQLite, which have a native REPLACE
2134          * statement.
2135          *
2136          * @param string $table Table name
2137          * @param array|string $rows Row(s) to insert
2138          * @param string $fname Caller function name
2139          *
2140          * @return ResultWrapper
2141          */
2142         protected function nativeReplace( $table, $rows, $fname ) {
2143                 $table = $this->tableName( $table );
2144
2145                 # Single row case
2146                 if ( !is_array( reset( $rows ) ) ) {
2147                         $rows = [ $rows ];
2148                 }
2149
2150                 $sql = "REPLACE INTO $table (" . implode( ',', array_keys( $rows[0] ) ) . ') VALUES ';
2151                 $first = true;
2152
2153                 foreach ( $rows as $row ) {
2154                         if ( $first ) {
2155                                 $first = false;
2156                         } else {
2157                                 $sql .= ',';
2158                         }
2159
2160                         $sql .= '(' . $this->makeList( $row ) . ')';
2161                 }
2162
2163                 return $this->query( $sql, $fname );
2164         }
2165
2166         public function upsert( $table, array $rows, array $uniqueIndexes, array $set,
2167                 $fname = __METHOD__
2168         ) {
2169                 if ( !count( $rows ) ) {
2170                         return true; // nothing to do
2171                 }
2172
2173                 if ( !is_array( reset( $rows ) ) ) {
2174                         $rows = [ $rows ];
2175                 }
2176
2177                 if ( count( $uniqueIndexes ) ) {
2178                         $clauses = []; // list WHERE clauses that each identify a single row
2179                         foreach ( $rows as $row ) {
2180                                 foreach ( $uniqueIndexes as $index ) {
2181                                         $index = is_array( $index ) ? $index : [ $index ]; // columns
2182                                         $rowKey = []; // unique key to this row
2183                                         foreach ( $index as $column ) {
2184                                                 $rowKey[$column] = $row[$column];
2185                                         }
2186                                         $clauses[] = $this->makeList( $rowKey, self::LIST_AND );
2187                                 }
2188                         }
2189                         $where = [ $this->makeList( $clauses, self::LIST_OR ) ];
2190                 } else {
2191                         $where = false;
2192                 }
2193
2194                 $useTrx = !$this->mTrxLevel;
2195                 if ( $useTrx ) {
2196                         $this->begin( $fname, self::TRANSACTION_INTERNAL );
2197                 }
2198                 try {
2199                         # Update any existing conflicting row(s)
2200                         if ( $where !== false ) {
2201                                 $ok = $this->update( $table, $set, $where, $fname );
2202                         } else {
2203                                 $ok = true;
2204                         }
2205                         # Now insert any non-conflicting row(s)
2206                         $ok = $this->insert( $table, $rows, $fname, [ 'IGNORE' ] ) && $ok;
2207                 } catch ( Exception $e ) {
2208                         if ( $useTrx ) {
2209                                 $this->rollback( $fname, self::FLUSHING_INTERNAL );
2210                         }
2211                         throw $e;
2212                 }
2213                 if ( $useTrx ) {
2214                         $this->commit( $fname, self::FLUSHING_INTERNAL );
2215                 }
2216
2217                 return $ok;
2218         }
2219
2220         public function deleteJoin( $delTable, $joinTable, $delVar, $joinVar, $conds,
2221                 $fname = __METHOD__
2222         ) {
2223                 if ( !$conds ) {
2224                         throw new DBUnexpectedError( $this, __METHOD__ . ' called with empty $conds' );
2225                 }
2226
2227                 $delTable = $this->tableName( $delTable );
2228                 $joinTable = $this->tableName( $joinTable );
2229                 $sql = "DELETE FROM $delTable WHERE $delVar IN (SELECT $joinVar FROM $joinTable ";
2230                 if ( $conds != '*' ) {
2231                         $sql .= 'WHERE ' . $this->makeList( $conds, self::LIST_AND );
2232                 }
2233                 $sql .= ')';
2234
2235                 $this->query( $sql, $fname );
2236         }
2237
2238         public function textFieldSize( $table, $field ) {
2239                 $table = $this->tableName( $table );
2240                 $sql = "SHOW COLUMNS FROM $table LIKE \"$field\";";
2241                 $res = $this->query( $sql, __METHOD__ );
2242                 $row = $this->fetchObject( $res );
2243
2244                 $m = [];
2245
2246                 if ( preg_match( '/\((.*)\)/', $row->Type, $m ) ) {
2247                         $size = $m[1];
2248                 } else {
2249                         $size = -1;
2250                 }
2251
2252                 return $size;
2253         }
2254
2255         public function delete( $table, $conds, $fname = __METHOD__ ) {
2256                 if ( !$conds ) {
2257                         throw new DBUnexpectedError( $this, __METHOD__ . ' called with no conditions' );
2258                 }
2259
2260                 $table = $this->tableName( $table );
2261                 $sql = "DELETE FROM $table";
2262
2263                 if ( $conds != '*' ) {
2264                         if ( is_array( $conds ) ) {
2265                                 $conds = $this->makeList( $conds, self::LIST_AND );
2266                         }
2267                         $sql .= ' WHERE ' . $conds;
2268                 }
2269
2270                 return $this->query( $sql, $fname );
2271         }
2272
2273         public function insertSelect(
2274                 $destTable, $srcTable, $varMap, $conds,
2275                 $fname = __METHOD__, $insertOptions = [], $selectOptions = []
2276         ) {
2277                 if ( $this->cliMode ) {
2278                         // For massive migrations with downtime, we don't want to select everything
2279                         // into memory and OOM, so do all this native on the server side if possible.
2280                         return $this->nativeInsertSelect(
2281                                 $destTable,
2282                                 $srcTable,
2283                                 $varMap,
2284                                 $conds,
2285                                 $fname,
2286                                 $insertOptions,
2287                                 $selectOptions
2288                         );
2289                 }
2290
2291                 // For web requests, do a locking SELECT and then INSERT. This puts the SELECT burden
2292                 // on only the master (without needing row-based-replication). It also makes it easy to
2293                 // know how big the INSERT is going to be.
2294                 $fields = [];
2295                 foreach ( $varMap as $dstColumn => $sourceColumnOrSql ) {
2296                         $fields[] = $this->fieldNameWithAlias( $sourceColumnOrSql, $dstColumn );
2297                 }
2298                 $selectOptions[] = 'FOR UPDATE';
2299                 $res = $this->select( $srcTable, implode( ',', $fields ), $conds, $fname, $selectOptions );
2300                 if ( !$res ) {
2301                         return false;
2302                 }
2303
2304                 $rows = [];
2305                 foreach ( $res as $row ) {
2306                         $rows[] = (array)$row;
2307                 }
2308
2309                 return $this->insert( $destTable, $rows, $fname, $insertOptions );
2310         }
2311
2312         protected function nativeInsertSelect( $destTable, $srcTable, $varMap, $conds,
2313                 $fname = __METHOD__,
2314                 $insertOptions = [], $selectOptions = []
2315         ) {
2316                 $destTable = $this->tableName( $destTable );
2317
2318                 if ( !is_array( $insertOptions ) ) {
2319                         $insertOptions = [ $insertOptions ];
2320                 }
2321
2322                 $insertOptions = $this->makeInsertOptions( $insertOptions );
2323
2324                 if ( !is_array( $selectOptions ) ) {
2325                         $selectOptions = [ $selectOptions ];
2326                 }
2327
2328                 list( $startOpts, $useIndex, $tailOpts, $ignoreIndex ) = $this->makeSelectOptions(
2329                         $selectOptions );
2330
2331                 if ( is_array( $srcTable ) ) {
2332                         $srcTable = implode( ',', array_map( [ &$this, 'tableName' ], $srcTable ) );
2333                 } else {
2334                         $srcTable = $this->tableName( $srcTable );
2335                 }
2336
2337                 $sql = "INSERT $insertOptions" .
2338                         " INTO $destTable (" . implode( ',', array_keys( $varMap ) ) . ')' .
2339                         " SELECT $startOpts " . implode( ',', $varMap ) .
2340                         " FROM $srcTable $useIndex $ignoreIndex ";
2341
2342                 if ( $conds != '*' ) {
2343                         if ( is_array( $conds ) ) {
2344                                 $conds = $this->makeList( $conds, self::LIST_AND );
2345                         }
2346                         $sql .= " WHERE $conds";
2347                 }
2348
2349                 $sql .= " $tailOpts";
2350
2351                 return $this->query( $sql, $fname );
2352         }
2353
2354         /**
2355          * Construct a LIMIT query with optional offset. This is used for query
2356          * pages. The SQL should be adjusted so that only the first $limit rows
2357          * are returned. If $offset is provided as well, then the first $offset
2358          * rows should be discarded, and the next $limit rows should be returned.
2359          * If the result of the query is not ordered, then the rows to be returned
2360          * are theoretically arbitrary.
2361          *
2362          * $sql is expected to be a SELECT, if that makes a difference.
2363          *
2364          * The version provided by default works in MySQL and SQLite. It will very
2365          * likely need to be overridden for most other DBMSes.
2366          *
2367          * @param string $sql SQL query we will append the limit too
2368          * @param int $limit The SQL limit
2369          * @param int|bool $offset The SQL offset (default false)
2370          * @throws DBUnexpectedError
2371          * @return string
2372          */
2373         public function limitResult( $sql, $limit, $offset = false ) {
2374                 if ( !is_numeric( $limit ) ) {
2375                         throw new DBUnexpectedError( $this,
2376                                 "Invalid non-numeric limit passed to limitResult()\n" );
2377                 }
2378
2379                 return "$sql LIMIT "
2380                 . ( ( is_numeric( $offset ) && $offset != 0 ) ? "{$offset}," : "" )
2381                 . "{$limit} ";
2382         }
2383
2384         public function unionSupportsOrderAndLimit() {
2385                 return true; // True for almost every DB supported
2386         }
2387
2388         public function unionQueries( $sqls, $all ) {
2389                 $glue = $all ? ') UNION ALL (' : ') UNION (';
2390
2391                 return '(' . implode( $glue, $sqls ) . ')';
2392         }
2393
2394         public function conditional( $cond, $trueVal, $falseVal ) {
2395                 if ( is_array( $cond ) ) {
2396                         $cond = $this->makeList( $cond, self::LIST_AND );
2397                 }
2398
2399                 return " (CASE WHEN $cond THEN $trueVal ELSE $falseVal END) ";
2400         }
2401
2402         public function strreplace( $orig, $old, $new ) {
2403                 return "REPLACE({$orig}, {$old}, {$new})";
2404         }
2405
2406         public function getServerUptime() {
2407                 return 0;
2408         }
2409
2410         public function wasDeadlock() {
2411                 return false;
2412         }
2413
2414         public function wasLockTimeout() {
2415                 return false;
2416         }
2417
2418         public function wasErrorReissuable() {
2419                 return false;
2420         }
2421
2422         public function wasReadOnlyError() {
2423                 return false;
2424         }
2425
2426         /**
2427          * Do not use this method outside of Database/DBError classes
2428          *
2429          * @param integer|string $errno
2430          * @return bool Whether the given query error was a connection drop
2431          */
2432         public function wasConnectionError( $errno ) {
2433                 return false;
2434         }
2435
2436         public function deadlockLoop() {
2437                 $args = func_get_args();
2438                 $function = array_shift( $args );
2439                 $tries = self::DEADLOCK_TRIES;
2440
2441                 $this->begin( __METHOD__ );
2442
2443                 $retVal = null;
2444                 /** @var Exception $e */
2445                 $e = null;
2446                 do {
2447                         try {
2448                                 $retVal = call_user_func_array( $function, $args );
2449                                 break;
2450                         } catch ( DBQueryError $e ) {
2451                                 if ( $this->wasDeadlock() ) {
2452                                         // Retry after a randomized delay
2453                                         usleep( mt_rand( self::DEADLOCK_DELAY_MIN, self::DEADLOCK_DELAY_MAX ) );
2454                                 } else {
2455                                         // Throw the error back up
2456                                         throw $e;
2457                                 }
2458                         }
2459                 } while ( --$tries > 0 );
2460
2461                 if ( $tries <= 0 ) {
2462                         // Too many deadlocks; give up
2463                         $this->rollback( __METHOD__ );
2464                         throw $e;
2465                 } else {
2466                         $this->commit( __METHOD__ );
2467
2468                         return $retVal;
2469                 }
2470         }
2471
2472         public function masterPosWait( DBMasterPos $pos, $timeout ) {
2473                 # Real waits are implemented in the subclass.
2474                 return 0;
2475         }
2476
2477         public function getReplicaPos() {
2478                 # Stub
2479                 return false;
2480         }
2481
2482         public function getMasterPos() {
2483                 # Stub
2484                 return false;
2485         }
2486
2487         public function serverIsReadOnly() {
2488                 return false;
2489         }
2490
2491         final public function onTransactionResolution( callable $callback, $fname = __METHOD__ ) {
2492                 if ( !$this->mTrxLevel ) {
2493                         throw new DBUnexpectedError( $this, "No transaction is active." );
2494                 }
2495                 $this->mTrxEndCallbacks[] = [ $callback, $fname ];
2496         }
2497
2498         final public function onTransactionIdle( callable $callback, $fname = __METHOD__ ) {
2499                 $this->mTrxIdleCallbacks[] = [ $callback, $fname ];
2500                 if ( !$this->mTrxLevel ) {
2501                         $this->runOnTransactionIdleCallbacks( self::TRIGGER_IDLE );
2502                 }
2503         }
2504
2505         final public function onTransactionPreCommitOrIdle( callable $callback, $fname = __METHOD__ ) {
2506                 if ( $this->mTrxLevel ) {
2507                         $this->mTrxPreCommitCallbacks[] = [ $callback, $fname ];
2508                 } else {
2509                         // If no transaction is active, then make one for this callback
2510                         $this->startAtomic( __METHOD__ );
2511                         try {
2512                                 call_user_func( $callback );
2513                                 $this->endAtomic( __METHOD__ );
2514                         } catch ( Exception $e ) {
2515                                 $this->rollback( __METHOD__, self::FLUSHING_INTERNAL );
2516                                 throw $e;
2517                         }
2518                 }
2519         }
2520
2521         final public function setTransactionListener( $name, callable $callback = null ) {
2522                 if ( $callback ) {
2523                         $this->mTrxRecurringCallbacks[$name] = $callback;
2524                 } else {
2525                         unset( $this->mTrxRecurringCallbacks[$name] );
2526                 }
2527         }
2528
2529         /**
2530          * Whether to disable running of post-COMMIT/ROLLBACK callbacks
2531          *
2532          * This method should not be used outside of Database/LoadBalancer
2533          *
2534          * @param bool $suppress
2535          * @since 1.28
2536          */
2537         final public function setTrxEndCallbackSuppression( $suppress ) {
2538                 $this->mTrxEndCallbacksSuppressed = $suppress;
2539         }
2540
2541         /**
2542          * Actually run and consume any "on transaction idle/resolution" callbacks.
2543          *
2544          * This method should not be used outside of Database/LoadBalancer
2545          *
2546          * @param integer $trigger IDatabase::TRIGGER_* constant
2547          * @since 1.20
2548          * @throws Exception
2549          */
2550         public function runOnTransactionIdleCallbacks( $trigger ) {
2551                 if ( $this->mTrxEndCallbacksSuppressed ) {
2552                         return;
2553                 }
2554
2555                 $autoTrx = $this->getFlag( self::DBO_TRX ); // automatic begin() enabled?
2556                 /** @var Exception $e */
2557                 $e = null; // first exception
2558                 do { // callbacks may add callbacks :)
2559                         $callbacks = array_merge(
2560                                 $this->mTrxIdleCallbacks,
2561                                 $this->mTrxEndCallbacks // include "transaction resolution" callbacks
2562                         );
2563                         $this->mTrxIdleCallbacks = []; // consumed (and recursion guard)
2564                         $this->mTrxEndCallbacks = []; // consumed (recursion guard)
2565                         foreach ( $callbacks as $callback ) {
2566                                 try {
2567                                         list( $phpCallback ) = $callback;
2568                                         $this->clearFlag( self::DBO_TRX ); // make each query its own transaction
2569                                         call_user_func_array( $phpCallback, [ $trigger ] );
2570                                         if ( $autoTrx ) {
2571                                                 $this->setFlag( self::DBO_TRX ); // restore automatic begin()
2572                                         } else {
2573                                                 $this->clearFlag( self::DBO_TRX ); // restore auto-commit
2574                                         }
2575                                 } catch ( Exception $ex ) {
2576                                         call_user_func( $this->errorLogger, $ex );
2577                                         $e = $e ?: $ex;
2578                                         // Some callbacks may use startAtomic/endAtomic, so make sure
2579                                         // their transactions are ended so other callbacks don't fail
2580                                         if ( $this->trxLevel() ) {
2581                                                 $this->rollback( __METHOD__, self::FLUSHING_INTERNAL );
2582                                         }
2583                                 }
2584                         }
2585                 } while ( count( $this->mTrxIdleCallbacks ) );
2586
2587                 if ( $e instanceof Exception ) {
2588                         throw $e; // re-throw any first exception
2589                 }
2590         }
2591
2592         /**
2593          * Actually run and consume any "on transaction pre-commit" callbacks.
2594          *
2595          * This method should not be used outside of Database/LoadBalancer
2596          *
2597          * @since 1.22
2598          * @throws Exception
2599          */
2600         public function runOnTransactionPreCommitCallbacks() {
2601                 $e = null; // first exception
2602                 do { // callbacks may add callbacks :)
2603                         $callbacks = $this->mTrxPreCommitCallbacks;
2604                         $this->mTrxPreCommitCallbacks = []; // consumed (and recursion guard)
2605                         foreach ( $callbacks as $callback ) {
2606                                 try {
2607                                         list( $phpCallback ) = $callback;
2608                                         call_user_func( $phpCallback );
2609                                 } catch ( Exception $ex ) {
2610                                         call_user_func( $this->errorLogger, $ex );
2611                                         $e = $e ?: $ex;
2612                                 }
2613                         }
2614                 } while ( count( $this->mTrxPreCommitCallbacks ) );
2615
2616                 if ( $e instanceof Exception ) {
2617                         throw $e; // re-throw any first exception
2618                 }
2619         }
2620
2621         /**
2622          * Actually run any "transaction listener" callbacks.
2623          *
2624          * This method should not be used outside of Database/LoadBalancer
2625          *
2626          * @param integer $trigger IDatabase::TRIGGER_* constant
2627          * @throws Exception
2628          * @since 1.20
2629          */
2630         public function runTransactionListenerCallbacks( $trigger ) {
2631                 if ( $this->mTrxEndCallbacksSuppressed ) {
2632                         return;
2633                 }
2634
2635                 /** @var Exception $e */
2636                 $e = null; // first exception
2637
2638                 foreach ( $this->mTrxRecurringCallbacks as $phpCallback ) {
2639                         try {
2640                                 $phpCallback( $trigger, $this );
2641                         } catch ( Exception $ex ) {
2642                                 call_user_func( $this->errorLogger, $ex );
2643                                 $e = $e ?: $ex;
2644                         }
2645                 }
2646
2647                 if ( $e instanceof Exception ) {
2648                         throw $e; // re-throw any first exception
2649                 }
2650         }
2651
2652         final public function startAtomic( $fname = __METHOD__ ) {
2653                 if ( !$this->mTrxLevel ) {
2654                         $this->begin( $fname, self::TRANSACTION_INTERNAL );
2655                         // If DBO_TRX is set, a series of startAtomic/endAtomic pairs will result
2656                         // in all changes being in one transaction to keep requests transactional.
2657                         if ( !$this->getFlag( self::DBO_TRX ) ) {
2658                                 $this->mTrxAutomaticAtomic = true;
2659                         }
2660                 }
2661
2662                 $this->mTrxAtomicLevels[] = $fname;
2663         }
2664
2665         final public function endAtomic( $fname = __METHOD__ ) {
2666                 if ( !$this->mTrxLevel ) {
2667                         throw new DBUnexpectedError( $this, "No atomic transaction is open (got $fname)." );
2668                 }
2669                 if ( !$this->mTrxAtomicLevels ||
2670                         array_pop( $this->mTrxAtomicLevels ) !== $fname
2671                 ) {
2672                         throw new DBUnexpectedError( $this, "Invalid atomic section ended (got $fname)." );
2673                 }
2674
2675                 if ( !$this->mTrxAtomicLevels && $this->mTrxAutomaticAtomic ) {
2676                         $this->commit( $fname, self::FLUSHING_INTERNAL );
2677                 }
2678         }
2679
2680         final public function doAtomicSection( $fname, callable $callback ) {
2681                 $this->startAtomic( $fname );
2682                 try {
2683                         $res = call_user_func_array( $callback, [ $this, $fname ] );
2684                 } catch ( Exception $e ) {
2685                         $this->rollback( $fname, self::FLUSHING_INTERNAL );
2686                         throw $e;
2687                 }
2688                 $this->endAtomic( $fname );
2689
2690                 return $res;
2691         }
2692
2693         final public function begin( $fname = __METHOD__, $mode = self::TRANSACTION_EXPLICIT ) {
2694                 // Protect against mismatched atomic section, transaction nesting, and snapshot loss
2695                 if ( $this->mTrxLevel ) {
2696                         if ( $this->mTrxAtomicLevels ) {
2697                                 $levels = implode( ', ', $this->mTrxAtomicLevels );
2698                                 $msg = "$fname: Got explicit BEGIN while atomic section(s) $levels are open.";
2699                                 throw new DBUnexpectedError( $this, $msg );
2700                         } elseif ( !$this->mTrxAutomatic ) {
2701                                 $msg = "$fname: Explicit transaction already active (from {$this->mTrxFname}).";
2702                                 throw new DBUnexpectedError( $this, $msg );
2703                         } else {
2704                                 // @TODO: make this an exception at some point
2705                                 $msg = "$fname: Implicit transaction already active (from {$this->mTrxFname}).";
2706                                 $this->queryLogger->error( $msg );
2707                                 return; // join the main transaction set
2708                         }
2709                 } elseif ( $this->getFlag( self::DBO_TRX ) && $mode !== self::TRANSACTION_INTERNAL ) {
2710                         // @TODO: make this an exception at some point
2711                         $msg = "$fname: Implicit transaction expected (DBO_TRX set).";
2712                         $this->queryLogger->error( $msg );
2713                         return; // let any writes be in the main transaction
2714                 }
2715
2716                 // Avoid fatals if close() was called
2717                 $this->assertOpen();
2718
2719                 $this->doBegin( $fname );
2720                 $this->mTrxTimestamp = microtime( true );
2721                 $this->mTrxFname = $fname;
2722                 $this->mTrxDoneWrites = false;
2723                 $this->mTrxAutomaticAtomic = false;
2724                 $this->mTrxAtomicLevels = [];
2725                 $this->mTrxShortId = sprintf( '%06x', mt_rand( 0, 0xffffff ) );
2726                 $this->mTrxWriteDuration = 0.0;
2727                 $this->mTrxWriteQueryCount = 0;
2728                 $this->mTrxWriteAdjDuration = 0.0;
2729                 $this->mTrxWriteAdjQueryCount = 0;
2730                 $this->mTrxWriteCallers = [];
2731                 // First SELECT after BEGIN will establish the snapshot in REPEATABLE-READ.
2732                 // Get an estimate of the replica DB lag before then, treating estimate staleness
2733                 // as lag itself just to be safe
2734                 $status = $this->getApproximateLagStatus();
2735                 $this->mTrxReplicaLag = $status['lag'] + ( microtime( true ) - $status['since'] );
2736                 // T147697: make explicitTrxActive() return true until begin() finishes. This way, no
2737                 // caller will think its OK to muck around with the transaction just because startAtomic()
2738                 // has not yet completed (e.g. setting mTrxAtomicLevels).
2739                 $this->mTrxAutomatic = ( $mode === self::TRANSACTION_INTERNAL );
2740         }
2741
2742         /**
2743          * Issues the BEGIN command to the database server.
2744          *
2745          * @see Database::begin()
2746          * @param string $fname
2747          */
2748         protected function doBegin( $fname ) {
2749                 $this->query( 'BEGIN', $fname );
2750                 $this->mTrxLevel = 1;
2751         }
2752
2753         final public function commit( $fname = __METHOD__, $flush = '' ) {
2754                 if ( $this->mTrxLevel && $this->mTrxAtomicLevels ) {
2755                         // There are still atomic sections open. This cannot be ignored
2756                         $levels = implode( ', ', $this->mTrxAtomicLevels );
2757                         throw new DBUnexpectedError(
2758                                 $this,
2759                                 "$fname: Got COMMIT while atomic sections $levels are still open."
2760                         );
2761                 }
2762
2763                 if ( $flush === self::FLUSHING_INTERNAL || $flush === self::FLUSHING_ALL_PEERS ) {
2764                         if ( !$this->mTrxLevel ) {
2765                                 return; // nothing to do
2766                         } elseif ( !$this->mTrxAutomatic ) {
2767                                 throw new DBUnexpectedError(
2768                                         $this,
2769                                         "$fname: Flushing an explicit transaction, getting out of sync."
2770                                 );
2771                         }
2772                 } else {
2773                         if ( !$this->mTrxLevel ) {
2774                                 $this->queryLogger->error(
2775                                         "$fname: No transaction to commit, something got out of sync." );
2776                                 return; // nothing to do
2777                         } elseif ( $this->mTrxAutomatic ) {
2778                                 // @TODO: make this an exception at some point
2779                                 $msg = "$fname: Explicit commit of implicit transaction.";
2780                                 $this->queryLogger->error( $msg );
2781                                 return; // wait for the main transaction set commit round
2782                         }
2783                 }
2784
2785                 // Avoid fatals if close() was called
2786                 $this->assertOpen();
2787
2788                 $this->runOnTransactionPreCommitCallbacks();
2789                 $writeTime = $this->pendingWriteQueryDuration( self::ESTIMATE_DB_APPLY );
2790                 $this->doCommit( $fname );
2791                 if ( $this->mTrxDoneWrites ) {
2792                         $this->mLastWriteTime = microtime( true );
2793                         $this->trxProfiler->transactionWritingOut(
2794                                 $this->mServer, $this->mDBname, $this->mTrxShortId, $writeTime );
2795                 }
2796
2797                 $this->runOnTransactionIdleCallbacks( self::TRIGGER_COMMIT );
2798                 $this->runTransactionListenerCallbacks( self::TRIGGER_COMMIT );
2799         }
2800
2801         /**
2802          * Issues the COMMIT command to the database server.
2803          *
2804          * @see Database::commit()
2805          * @param string $fname
2806          */
2807         protected function doCommit( $fname ) {
2808                 if ( $this->mTrxLevel ) {
2809                         $this->query( 'COMMIT', $fname );
2810                         $this->mTrxLevel = 0;
2811                 }
2812         }
2813
2814         final public function rollback( $fname = __METHOD__, $flush = '' ) {
2815                 if ( $flush === self::FLUSHING_INTERNAL || $flush === self::FLUSHING_ALL_PEERS ) {
2816                         if ( !$this->mTrxLevel ) {
2817                                 return; // nothing to do
2818                         }
2819                 } else {
2820                         if ( !$this->mTrxLevel ) {
2821                                 $this->queryLogger->error(
2822                                         "$fname: No transaction to rollback, something got out of sync." );
2823                                 return; // nothing to do
2824                         } elseif ( $this->getFlag( self::DBO_TRX ) ) {
2825                                 throw new DBUnexpectedError(
2826                                         $this,
2827                                         "$fname: Expected mass rollback of all peer databases (DBO_TRX set)."
2828                                 );
2829                         }
2830                 }
2831
2832                 // Avoid fatals if close() was called
2833                 $this->assertOpen();
2834
2835                 $this->doRollback( $fname );
2836                 $this->mTrxAtomicLevels = [];
2837                 if ( $this->mTrxDoneWrites ) {
2838                         $this->trxProfiler->transactionWritingOut(
2839                                 $this->mServer, $this->mDBname, $this->mTrxShortId );
2840                 }
2841
2842                 $this->mTrxIdleCallbacks = []; // clear
2843                 $this->mTrxPreCommitCallbacks = []; // clear
2844                 $this->runOnTransactionIdleCallbacks( self::TRIGGER_ROLLBACK );
2845                 $this->runTransactionListenerCallbacks( self::TRIGGER_ROLLBACK );
2846         }
2847
2848         /**
2849          * Issues the ROLLBACK command to the database server.
2850          *
2851          * @see Database::rollback()
2852          * @param string $fname
2853          */
2854         protected function doRollback( $fname ) {
2855                 if ( $this->mTrxLevel ) {
2856                         # Disconnects cause rollback anyway, so ignore those errors
2857                         $ignoreErrors = true;
2858                         $this->query( 'ROLLBACK', $fname, $ignoreErrors );
2859                         $this->mTrxLevel = 0;
2860                 }
2861         }
2862
2863         public function flushSnapshot( $fname = __METHOD__ ) {
2864                 if ( $this->writesOrCallbacksPending() || $this->explicitTrxActive() ) {
2865                         // This only flushes transactions to clear snapshots, not to write data
2866                         $fnames = implode( ', ', $this->pendingWriteAndCallbackCallers() );
2867                         throw new DBUnexpectedError(
2868                                 $this,
2869                                 "$fname: Cannot flush snapshot because writes are pending ($fnames)."
2870                         );
2871                 }
2872
2873                 $this->commit( $fname, self::FLUSHING_INTERNAL );
2874         }
2875
2876         public function explicitTrxActive() {
2877                 return $this->mTrxLevel && ( $this->mTrxAtomicLevels || !$this->mTrxAutomatic );
2878         }
2879
2880         /**
2881          * Creates a new table with structure copied from existing table
2882          * Note that unlike most database abstraction functions, this function does not
2883          * automatically append database prefix, because it works at a lower
2884          * abstraction level.
2885          * The table names passed to this function shall not be quoted (this
2886          * function calls addIdentifierQuotes when needed).
2887          *
2888          * @param string $oldName Name of table whose structure should be copied
2889          * @param string $newName Name of table to be created
2890          * @param bool $temporary Whether the new table should be temporary
2891          * @param string $fname Calling function name
2892          * @throws RuntimeException
2893          * @return bool True if operation was successful
2894          */
2895         public function duplicateTableStructure( $oldName, $newName, $temporary = false,
2896                 $fname = __METHOD__
2897         ) {
2898                 throw new RuntimeException( __METHOD__ . ' is not implemented in descendant class' );
2899         }
2900
2901         public function listTables( $prefix = null, $fname = __METHOD__ ) {
2902                 throw new RuntimeException( __METHOD__ . ' is not implemented in descendant class' );
2903         }
2904
2905         public function listViews( $prefix = null, $fname = __METHOD__ ) {
2906                 throw new RuntimeException( __METHOD__ . ' is not implemented in descendant class' );
2907         }
2908
2909         public function timestamp( $ts = 0 ) {
2910                 $t = new ConvertibleTimestamp( $ts );
2911                 // Let errors bubble up to avoid putting garbage in the DB
2912                 return $t->getTimestamp( TS_MW );
2913         }
2914
2915         public function timestampOrNull( $ts = null ) {
2916                 if ( is_null( $ts ) ) {
2917                         return null;
2918                 } else {
2919                         return $this->timestamp( $ts );
2920                 }
2921         }
2922
2923         /**
2924          * Take the result from a query, and wrap it in a ResultWrapper if
2925          * necessary. Boolean values are passed through as is, to indicate success
2926          * of write queries or failure.
2927          *
2928          * Once upon a time, Database::query() returned a bare MySQL result
2929          * resource, and it was necessary to call this function to convert it to
2930          * a wrapper. Nowadays, raw database objects are never exposed to external
2931          * callers, so this is unnecessary in external code.
2932          *
2933          * @param bool|ResultWrapper|resource|object $result
2934          * @return bool|ResultWrapper
2935          */
2936         protected function resultObject( $result ) {
2937                 if ( !$result ) {
2938                         return false;
2939                 } elseif ( $result instanceof ResultWrapper ) {
2940                         return $result;
2941                 } elseif ( $result === true ) {
2942                         // Successful write query
2943                         return $result;
2944                 } else {
2945                         return new ResultWrapper( $this, $result );
2946                 }
2947         }
2948
2949         public function ping( &$rtt = null ) {
2950                 // Avoid hitting the server if it was hit recently
2951                 if ( $this->isOpen() && ( microtime( true ) - $this->lastPing ) < self::PING_TTL ) {
2952                         if ( !func_num_args() || $this->mRTTEstimate > 0 ) {
2953                                 $rtt = $this->mRTTEstimate;
2954                                 return true; // don't care about $rtt
2955                         }
2956                 }
2957
2958                 // This will reconnect if possible or return false if not
2959                 $this->clearFlag( self::DBO_TRX, self::REMEMBER_PRIOR );
2960                 $ok = ( $this->query( self::PING_QUERY, __METHOD__, true ) !== false );
2961                 $this->restoreFlags( self::RESTORE_PRIOR );
2962
2963                 if ( $ok ) {
2964                         $rtt = $this->mRTTEstimate;
2965                 }
2966
2967                 return $ok;
2968         }
2969
2970         /**
2971          * @return bool
2972          */
2973         protected function reconnect() {
2974                 $this->closeConnection();
2975                 $this->mOpened = false;
2976                 $this->mConn = false;
2977                 try {
2978                         $this->open( $this->mServer, $this->mUser, $this->mPassword, $this->mDBname );
2979                         $this->lastPing = microtime( true );
2980                         $ok = true;
2981                 } catch ( DBConnectionError $e ) {
2982                         $ok = false;
2983                 }
2984
2985                 return $ok;
2986         }
2987
2988         public function getSessionLagStatus() {
2989                 return $this->getTransactionLagStatus() ?: $this->getApproximateLagStatus();
2990         }
2991
2992         /**
2993          * Get the replica DB lag when the current transaction started
2994          *
2995          * This is useful when transactions might use snapshot isolation
2996          * (e.g. REPEATABLE-READ in innodb), so the "real" lag of that data
2997          * is this lag plus transaction duration. If they don't, it is still
2998          * safe to be pessimistic. This returns null if there is no transaction.
2999          *
3000          * @return array|null ('lag': seconds or false on error, 'since': UNIX timestamp of BEGIN)
3001          * @since 1.27
3002          */
3003         protected function getTransactionLagStatus() {
3004                 return $this->mTrxLevel
3005                         ? [ 'lag' => $this->mTrxReplicaLag, 'since' => $this->trxTimestamp() ]
3006                         : null;
3007         }
3008
3009         /**
3010          * Get a replica DB lag estimate for this server
3011          *
3012          * @return array ('lag': seconds or false on error, 'since': UNIX timestamp of estimate)
3013          * @since 1.27
3014          */
3015         protected function getApproximateLagStatus() {
3016                 return [
3017                         'lag'   => $this->getLBInfo( 'replica' ) ? $this->getLag() : 0,
3018                         'since' => microtime( true )
3019                 ];
3020         }
3021
3022         /**
3023          * Merge the result of getSessionLagStatus() for several DBs
3024          * using the most pessimistic values to estimate the lag of
3025          * any data derived from them in combination
3026          *
3027          * This is information is useful for caching modules
3028          *
3029          * @see WANObjectCache::set()
3030          * @see WANObjectCache::getWithSetCallback()
3031          *
3032          * @param IDatabase $db1
3033          * @param IDatabase ...
3034          * @return array Map of values:
3035          *   - lag: highest lag of any of the DBs or false on error (e.g. replication stopped)
3036          *   - since: oldest UNIX timestamp of any of the DB lag estimates
3037          *   - pending: whether any of the DBs have uncommitted changes
3038          * @since 1.27
3039          */
3040         public static function getCacheSetOptions( IDatabase $db1 ) {
3041                 $opts = [ 'lag' => 0, 'since' => INF, 'pending' => false ];
3042                 foreach ( func_get_args() as $db ) {
3043                         /** @var IDatabase $db */
3044                         $dbOpts = $db->getSessionLagStatus();
3045                         $dbOpts['pending'] = $db->writesPending();
3046                         $opts = self::mergeCacheSetOptions( $opts, $dbOpts );
3047                 }
3048
3049                 return $opts;
3050         }
3051
3052         /**
3053          * @param array $base Map in the format of getCacheSetOptions() results
3054          * @param array $other Map in the format of getCacheSetOptions() results
3055          * @return array Pessimistically merged result of $base/$other in the format of $base
3056          * @since 1.28
3057          */
3058         public static function mergeCacheSetOptions( array $base, array $other ) {
3059                 if ( $other['lag'] === false ) {
3060                         $base['lag'] = false;
3061                 } elseif ( $base['lag'] !== false ) {
3062                         $base['lag'] = max( $base['lag'], $other['lag'] );
3063                 }
3064                 $base['since'] = min( $base['since'], $other['since'] );
3065                 $base['pending'] = $base['pending'] ?: $other['pending'];
3066
3067                 return $base;
3068         }
3069
3070         public function getLag() {
3071                 return 0;
3072         }
3073
3074         public function maxListLen() {
3075                 return 0;
3076         }
3077
3078         public function encodeBlob( $b ) {
3079                 return $b;
3080         }
3081
3082         public function decodeBlob( $b ) {
3083                 if ( $b instanceof Blob ) {
3084                         $b = $b->fetch();
3085                 }
3086                 return $b;
3087         }
3088
3089         public function setSessionOptions( array $options ) {
3090         }
3091
3092         public function sourceFile(
3093                 $filename,
3094                 callable $lineCallback = null,
3095                 callable $resultCallback = null,
3096                 $fname = false,
3097                 callable $inputCallback = null
3098         ) {
3099                 MediaWiki\suppressWarnings();
3100                 $fp = fopen( $filename, 'r' );
3101                 MediaWiki\restoreWarnings();
3102
3103                 if ( false === $fp ) {
3104                         throw new RuntimeException( "Could not open \"{$filename}\".\n" );
3105                 }
3106
3107                 if ( !$fname ) {
3108                         $fname = __METHOD__ . "( $filename )";
3109                 }
3110
3111                 try {
3112                         $error = $this->sourceStream(
3113                                 $fp, $lineCallback, $resultCallback, $fname, $inputCallback );
3114                 } catch ( Exception $e ) {
3115                         fclose( $fp );
3116                         throw $e;
3117                 }
3118
3119                 fclose( $fp );
3120
3121                 return $error;
3122         }
3123
3124         public function setSchemaVars( $vars ) {
3125                 $this->mSchemaVars = $vars;
3126         }
3127
3128         public function sourceStream(
3129                 $fp,
3130                 callable $lineCallback = null,
3131                 callable $resultCallback = null,
3132                 $fname = __METHOD__,
3133                 callable $inputCallback = null
3134         ) {
3135                 $cmd = '';
3136
3137                 while ( !feof( $fp ) ) {
3138                         if ( $lineCallback ) {
3139                                 call_user_func( $lineCallback );
3140                         }
3141
3142                         $line = trim( fgets( $fp ) );
3143
3144                         if ( $line == '' ) {
3145                                 continue;
3146                         }
3147
3148                         if ( '-' == $line[0] && '-' == $line[1] ) {
3149                                 continue;
3150                         }
3151
3152                         if ( $cmd != '' ) {
3153                                 $cmd .= ' ';
3154                         }
3155
3156                         $done = $this->streamStatementEnd( $cmd, $line );
3157
3158                         $cmd .= "$line\n";
3159
3160                         if ( $done || feof( $fp ) ) {
3161                                 $cmd = $this->replaceVars( $cmd );
3162
3163                                 if ( !$inputCallback || call_user_func( $inputCallback, $cmd ) ) {
3164                                         $res = $this->query( $cmd, $fname );
3165
3166                                         if ( $resultCallback ) {
3167                                                 call_user_func( $resultCallback, $res, $this );
3168                                         }
3169
3170                                         if ( false === $res ) {
3171                                                 $err = $this->lastError();
3172
3173                                                 return "Query \"{$cmd}\" failed with error code \"$err\".\n";
3174                                         }
3175                                 }
3176                                 $cmd = '';
3177                         }
3178                 }
3179
3180                 return true;
3181         }
3182
3183         /**
3184          * Called by sourceStream() to check if we've reached a statement end
3185          *
3186          * @param string &$sql SQL assembled so far
3187          * @param string &$newLine New line about to be added to $sql
3188          * @return bool Whether $newLine contains end of the statement
3189          */
3190         public function streamStatementEnd( &$sql, &$newLine ) {
3191                 if ( $this->delimiter ) {
3192                         $prev = $newLine;
3193                         $newLine = preg_replace(
3194                                 '/' . preg_quote( $this->delimiter, '/' ) . '$/', '', $newLine );
3195                         if ( $newLine != $prev ) {
3196                                 return true;
3197                         }
3198                 }
3199
3200                 return false;
3201         }
3202
3203         /**
3204          * Database independent variable replacement. Replaces a set of variables
3205          * in an SQL statement with their contents as given by $this->getSchemaVars().
3206          *
3207          * Supports '{$var}' `{$var}` and / *$var* / (without the spaces) style variables.
3208          *
3209          * - '{$var}' should be used for text and is passed through the database's
3210          *   addQuotes method.
3211          * - `{$var}` should be used for identifiers (e.g. table and database names).
3212          *   It is passed through the database's addIdentifierQuotes method which
3213          *   can be overridden if the database uses something other than backticks.
3214          * - / *_* / or / *$wgDBprefix* / passes the name that follows through the
3215          *   database's tableName method.
3216          * - / *i* / passes the name that follows through the database's indexName method.
3217          * - In all other cases, / *$var* / is left unencoded. Except for table options,
3218          *   its use should be avoided. In 1.24 and older, string encoding was applied.
3219          *
3220          * @param string $ins SQL statement to replace variables in
3221          * @return string The new SQL statement with variables replaced
3222          */
3223         protected function replaceVars( $ins ) {
3224                 $vars = $this->getSchemaVars();
3225                 return preg_replace_callback(
3226                         '!
3227                                 /\* (\$wgDBprefix|[_i]) \*/ (\w*) | # 1-2. tableName, indexName
3228                                 \'\{\$ (\w+) }\'                  | # 3. addQuotes
3229                                 `\{\$ (\w+) }`                    | # 4. addIdentifierQuotes
3230                                 /\*\$ (\w+) \*/                     # 5. leave unencoded
3231                         !x',
3232                         function ( $m ) use ( $vars ) {
3233                                 // Note: Because of <https://bugs.php.net/bug.php?id=51881>,
3234                                 // check for both nonexistent keys *and* the empty string.
3235                                 if ( isset( $m[1] ) && $m[1] !== '' ) {
3236                                         if ( $m[1] === 'i' ) {
3237                                                 return $this->indexName( $m[2] );
3238                                         } else {
3239                                                 return $this->tableName( $m[2] );
3240                                         }
3241                                 } elseif ( isset( $m[3] ) && $m[3] !== '' && array_key_exists( $m[3], $vars ) ) {
3242                                         return $this->addQuotes( $vars[$m[3]] );
3243                                 } elseif ( isset( $m[4] ) && $m[4] !== '' && array_key_exists( $m[4], $vars ) ) {
3244                                         return $this->addIdentifierQuotes( $vars[$m[4]] );
3245                                 } elseif ( isset( $m[5] ) && $m[5] !== '' && array_key_exists( $m[5], $vars ) ) {
3246                                         return $vars[$m[5]];
3247                                 } else {
3248                                         return $m[0];
3249                                 }
3250                         },
3251                         $ins
3252                 );
3253         }
3254
3255         /**
3256          * Get schema variables. If none have been set via setSchemaVars(), then
3257          * use some defaults from the current object.
3258          *
3259          * @return array
3260          */
3261         protected function getSchemaVars() {
3262                 if ( $this->mSchemaVars ) {
3263                         return $this->mSchemaVars;
3264                 } else {
3265                         return $this->getDefaultSchemaVars();
3266                 }
3267         }
3268
3269         /**
3270          * Get schema variables to use if none have been set via setSchemaVars().
3271          *
3272          * Override this in derived classes to provide variables for tables.sql
3273          * and SQL patch files.
3274          *
3275          * @return array
3276          */
3277         protected function getDefaultSchemaVars() {
3278                 return [];
3279         }
3280
3281         public function lockIsFree( $lockName, $method ) {
3282                 return true;
3283         }
3284
3285         public function lock( $lockName, $method, $timeout = 5 ) {
3286                 $this->mNamedLocksHeld[$lockName] = 1;
3287
3288                 return true;
3289         }
3290
3291         public function unlock( $lockName, $method ) {
3292                 unset( $this->mNamedLocksHeld[$lockName] );
3293
3294                 return true;
3295         }
3296
3297         public function getScopedLockAndFlush( $lockKey, $fname, $timeout ) {
3298                 if ( $this->writesOrCallbacksPending() ) {
3299                         // This only flushes transactions to clear snapshots, not to write data
3300                         $fnames = implode( ', ', $this->pendingWriteAndCallbackCallers() );
3301                         throw new DBUnexpectedError(
3302                                 $this,
3303                                 "$fname: Cannot flush pre-lock snapshot because writes are pending ($fnames)."
3304                         );
3305                 }
3306
3307                 if ( !$this->lock( $lockKey, $fname, $timeout ) ) {
3308                         return null;
3309                 }
3310
3311                 $unlocker = new ScopedCallback( function () use ( $lockKey, $fname ) {
3312                         if ( $this->trxLevel() ) {
3313                                 // There is a good chance an exception was thrown, causing any early return
3314                                 // from the caller. Let any error handler get a chance to issue rollback().
3315                                 // If there isn't one, let the error bubble up and trigger server-side rollback.
3316                                 $this->onTransactionResolution(
3317                                         function () use ( $lockKey, $fname ) {
3318                                                 $this->unlock( $lockKey, $fname );
3319                                         },
3320                                         $fname
3321                                 );
3322                         } else {
3323                                 $this->unlock( $lockKey, $fname );
3324                         }
3325                 } );
3326
3327                 $this->commit( $fname, self::FLUSHING_INTERNAL );
3328
3329                 return $unlocker;
3330         }
3331
3332         public function namedLocksEnqueue() {
3333                 return false;
3334         }
3335
3336         /**
3337          * Lock specific tables
3338          *
3339          * @param array $read Array of tables to lock for read access
3340          * @param array $write Array of tables to lock for write access
3341          * @param string $method Name of caller
3342          * @param bool $lowPriority Whether to indicate writes to be LOW PRIORITY
3343          * @return bool
3344          */
3345         public function lockTables( $read, $write, $method, $lowPriority = true ) {
3346                 return true;
3347         }
3348
3349         /**
3350          * Unlock specific tables
3351          *
3352          * @param string $method The caller
3353          * @return bool
3354          */
3355         public function unlockTables( $method ) {
3356                 return true;
3357         }
3358
3359         /**
3360          * Delete a table
3361          * @param string $tableName
3362          * @param string $fName
3363          * @return bool|ResultWrapper
3364          * @since 1.18
3365          */
3366         public function dropTable( $tableName, $fName = __METHOD__ ) {
3367                 if ( !$this->tableExists( $tableName, $fName ) ) {
3368                         return false;
3369                 }
3370                 $sql = "DROP TABLE " . $this->tableName( $tableName ) . " CASCADE";
3371
3372                 return $this->query( $sql, $fName );
3373         }
3374
3375         public function getInfinity() {
3376                 return 'infinity';
3377         }
3378
3379         public function encodeExpiry( $expiry ) {
3380                 return ( $expiry == '' || $expiry == 'infinity' || $expiry == $this->getInfinity() )
3381                         ? $this->getInfinity()
3382                         : $this->timestamp( $expiry );
3383         }
3384
3385         public function decodeExpiry( $expiry, $format = TS_MW ) {
3386                 if ( $expiry == '' || $expiry == 'infinity' || $expiry == $this->getInfinity() ) {
3387                         return 'infinity';
3388                 }
3389
3390                 return ConvertibleTimestamp::convert( $format, $expiry );
3391         }
3392
3393         public function setBigSelects( $value = true ) {
3394                 // no-op
3395         }
3396
3397         public function isReadOnly() {
3398                 return ( $this->getReadOnlyReason() !== false );
3399         }
3400
3401         /**
3402          * @return string|bool Reason this DB is read-only or false if it is not
3403          */
3404         protected function getReadOnlyReason() {
3405                 $reason = $this->getLBInfo( 'readOnlyReason' );
3406
3407                 return is_string( $reason ) ? $reason : false;
3408         }
3409
3410         public function setTableAliases( array $aliases ) {
3411                 $this->tableAliases = $aliases;
3412         }
3413
3414         public function declareUsageSectionStart( $id ) {
3415                 $this->usageSectionInfo[$id] = [
3416                         'readQueries' => 0,
3417                         'writeQueries' => 0,
3418                         'cacheSetOptions' => null
3419                 ];
3420         }
3421
3422         public function declareUsageSectionEnd( $id ) {
3423                 if ( !isset( $this->usageSectionInfo[$id] ) ) {
3424                         throw new InvalidArgumentException( "No section with ID '$id'" );
3425                 }
3426
3427                 $info = $this->usageSectionInfo[$id];
3428                 unset( $this->usageSectionInfo[$id] );
3429
3430                 return $info;
3431         }
3432
3433         /**
3434          * @return bool Whether a DB user is required to access the DB
3435          * @since 1.28
3436          */
3437         protected function requiresDatabaseUser() {
3438                 return true;
3439         }
3440
3441         /**
3442          * Get the underlying binding handle, mConn
3443          *
3444          * Makes sure that mConn is set (disconnects and ping() failure can unset it).
3445          * This catches broken callers than catch and ignore disconnection exceptions.
3446          * Unlike checking isOpen(), this is safe to call inside of open().
3447          *
3448          * @return resource|object
3449          * @throws DBUnexpectedError
3450          * @since 1.26
3451          */
3452         protected function getBindingHandle() {
3453                 if ( !$this->mConn ) {
3454                         throw new DBUnexpectedError(
3455                                 $this,
3456                                 'DB connection was already closed or the connection dropped.'
3457                         );
3458                 }
3459
3460                 return $this->mConn;
3461         }
3462
3463         /**
3464          * @since 1.19
3465          * @return string
3466          */
3467         public function __toString() {
3468                 return (string)$this->mConn;
3469         }
3470
3471         /**
3472          * Make sure that copies do not share the same client binding handle
3473          * @throws DBConnectionError
3474          */
3475         public function __clone() {
3476                 $this->connLogger->warning(
3477                         "Cloning " . get_class( $this ) . " is not recomended; forking connection:\n" .
3478                         ( new RuntimeException() )->getTraceAsString()
3479                 );
3480
3481                 if ( $this->isOpen() ) {
3482                         // Open a new connection resource without messing with the old one
3483                         $this->mOpened = false;
3484                         $this->mConn = false;
3485                         $this->mTrxEndCallbacks = []; // don't copy
3486                         $this->handleSessionLoss(); // no trx or locks anymore
3487                         $this->open( $this->mServer, $this->mUser, $this->mPassword, $this->mDBname );
3488                         $this->lastPing = microtime( true );
3489                 }
3490         }
3491
3492         /**
3493          * Called by serialize. Throw an exception when DB connection is serialized.
3494          * This causes problems on some database engines because the connection is
3495          * not restored on unserialize.
3496          */
3497         public function __sleep() {
3498                 throw new RuntimeException( 'Database serialization may cause problems, since ' .
3499                         'the connection is not restored on wakeup.' );
3500         }
3501
3502         /**
3503          * Run a few simple sanity checks and close dangling connections
3504          */
3505         public function __destruct() {
3506                 if ( $this->mTrxLevel && $this->mTrxDoneWrites ) {
3507                         trigger_error( "Uncommitted DB writes (transaction from {$this->mTrxFname})." );
3508                 }
3509
3510                 $danglingWriters = $this->pendingWriteAndCallbackCallers();
3511                 if ( $danglingWriters ) {
3512                         $fnames = implode( ', ', $danglingWriters );
3513                         trigger_error( "DB transaction writes or callbacks still pending ($fnames)." );
3514                 }
3515
3516                 if ( $this->mConn ) {
3517                         // Avoid connection leaks for sanity. Normally, resources close at script completion.
3518                         // The connection might already be closed in zend/hhvm by now, so suppress warnings.
3519                         \MediaWiki\suppressWarnings();
3520                         $this->closeConnection();
3521                         \MediaWiki\restoreWarnings();
3522                         $this->mConn = false;
3523                         $this->mOpened = false;
3524                 }
3525         }
3526 }
3527
3528 class_alias( 'Database', 'DatabaseBase' );