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 namespace Wikimedia\Rdbms;
  27
  28 use Psr\Log\LoggerAwareInterface;
  29 use Psr\Log\LoggerInterface;
  30 use Wikimedia\ScopedCallback;
  31 use Wikimedia\Timestamp\ConvertibleTimestamp;
  32 use MediaWiki;
  33 use BagOStuff;
  34 use HashBagOStuff;
  35 use InvalidArgumentException;
  36 use Exception;
  37 use RuntimeException;
  38
  39 /**
  40  * Relational database abstraction object
  41  *
  42  * @ingroup Database
  43  * @since 1.28
  44  */
  45 abstract class Database implements IDatabase, IMaintainableDatabase, LoggerAwareInterface {
  46         /** Number of times to re-try an operation in case of deadlock */
  47         const DEADLOCK_TRIES = 4;
  48         /** Minimum time to wait before retry, in microseconds */
  49         const DEADLOCK_DELAY_MIN = 500000;
  50         /** Maximum time to wait before retry */
  51         const DEADLOCK_DELAY_MAX = 1500000;
  52
  53         /** How long before it is worth doing a dummy query to test the connection */
  54         const PING_TTL = 1.0;
  55         const PING_QUERY = 'SELECT 1 AS ping';
  56
  57         const TINY_WRITE_SEC = .010;
  58         const SLOW_WRITE_SEC = .500;
  59         const SMALL_WRITE_ROWS = 100;
  60
  61         /** @var string SQL query */
  62         protected $mLastQuery = '';
  63         /** @var float|bool UNIX timestamp of last write query */
  64         protected $mLastWriteTime = false;
  65         /** @var string|bool */
  66         protected $mPHPError = false;
  67         /** @var string */
  68         protected $mServer;
  69         /** @var string */
  70         protected $mUser;
  71         /** @var string */
  72         protected $mPassword;
  73         /** @var string */
  74         protected $mDBname;
  75         /** @var array[] $aliases Map of (table => (dbname, schema, prefix) map) */
  76         protected $tableAliases = [];
  77         /** @var bool Whether this PHP instance is for a CLI script */
  78         protected $cliMode;
  79         /** @var string Agent name for query profiling */
  80         protected $agent;
  81
  82         /** @var BagOStuff APC cache */
  83         protected $srvCache;
  84         /** @var LoggerInterface */
  85         protected $connLogger;
  86         /** @var LoggerInterface */
  87         protected $queryLogger;
  88         /** @var callback Error logging callback */
  89         protected $errorLogger;
  90
  91         /** @var resource|null Database connection */
  92         protected $mConn = null;
  93         /** @var bool */
  94         protected $mOpened = false;
  95
  96         /** @var array[] List of (callable, method name) */
  97         protected $mTrxIdleCallbacks = [];
  98         /** @var array[] List of (callable, method name) */
  99         protected $mTrxPreCommitCallbacks = [];
 100         /** @var array[] List of (callable, method name) */
 101         protected $mTrxEndCallbacks = [];
 102         /** @var callable[] Map of (name => callable) */
 103         protected $mTrxRecurringCallbacks = [];
 104         /** @var bool Whether to suppress triggering of transaction end callbacks */
 105         protected $mTrxEndCallbacksSuppressed = false;
 106
 107         /** @var string */
 108         protected $mTablePrefix = '';
 109         /** @var string */
 110         protected $mSchema = '';
 111         /** @var integer */
 112         protected $mFlags;
 113         /** @var array */
 114         protected $mLBInfo = [];
 115         /** @var bool|null */
 116         protected $mDefaultBigSelects = null;
 117         /** @var array|bool */
 118         protected $mSchemaVars = false;
 119         /** @var array */
 120         protected $mSessionVars = [];
 121         /** @var array|null */
 122         protected $preparedArgs;
 123         /** @var string|bool|null Stashed value of html_errors INI setting */
 124         protected $htmlErrors;
 125         /** @var string */
 126         protected $delimiter = ';';
 127         /** @var DatabaseDomain */
 128         protected $currentDomain;
 129
 130         /**
 131          * Either 1 if a transaction is active or 0 otherwise.
 132          * The other Trx fields may not be meaningfull if this is 0.
 133          *
 134          * @var int
 135          */
 136         protected $mTrxLevel = 0;
 137         /**
 138          * Either a short hexidecimal string if a transaction is active or ""
 139          *
 140          * @var string
 141          * @see Database::mTrxLevel
 142          */
 143         protected $mTrxShortId = '';
 144         /**
 145          * The UNIX time that the transaction started. Callers can assume that if
 146          * snapshot isolation is used, then the data is *at least* up to date to that
 147          * point (possibly more up-to-date since the first SELECT defines the snapshot).
 148          *
 149          * @var float|null
 150          * @see Database::mTrxLevel
 151          */
 152         private $mTrxTimestamp = null;
 153         /** @var float Lag estimate at the time of BEGIN */
 154         private $mTrxReplicaLag = null;
 155         /**
 156          * Remembers the function name given for starting the most recent transaction via begin().
 157          * Used to provide additional context for error reporting.
 158          *
 159          * @var string
 160          * @see Database::mTrxLevel
 161          */
 162         private $mTrxFname = null;
 163         /**
 164          * Record if possible write queries were done in the last transaction started
 165          *
 166          * @var bool
 167          * @see Database::mTrxLevel
 168          */
 169         private $mTrxDoneWrites = false;
 170         /**
 171          * Record if the current transaction was started implicitly due to DBO_TRX being set.
 172          *
 173          * @var bool
 174          * @see Database::mTrxLevel
 175          */
 176         private $mTrxAutomatic = false;
 177         /**
 178          * Array of levels of atomicity within transactions
 179          *
 180          * @var array
 181          */
 182         private $mTrxAtomicLevels = [];
 183         /**
 184          * Record if the current transaction was started implicitly by Database::startAtomic
 185          *
 186          * @var bool
 187          */
 188         private $mTrxAutomaticAtomic = false;
 189         /**
 190          * Track the write query callers of the current transaction
 191          *
 192          * @var string[]
 193          */
 194         private $mTrxWriteCallers = [];
 195         /**
 196          * @var float Seconds spent in write queries for the current transaction
 197          */
 198         private $mTrxWriteDuration = 0.0;
 199         /**
 200          * @var integer Number of write queries for the current transaction
 201          */
 202         private $mTrxWriteQueryCount = 0;
 203         /**
 204          * @var float Like mTrxWriteQueryCount but excludes lock-bound, easy to replicate, queries
 205          */
 206         private $mTrxWriteAdjDuration = 0.0;
 207         /**
 208          * @var integer Number of write queries counted in mTrxWriteAdjDuration
 209          */
 210         private $mTrxWriteAdjQueryCount = 0;
 211         /**
 212          * @var float RTT time estimate
 213          */
 214         private $mRTTEstimate = 0.0;
 215
 216         /** @var array Map of (name => 1) for locks obtained via lock() */
 217         private $mNamedLocksHeld = [];
 218         /** @var array Map of (table name => 1) for TEMPORARY tables */
 219         protected $mSessionTempTables = [];
 220
 221         /** @var IDatabase|null Lazy handle to the master DB this server replicates from */
 222         private $lazyMasterHandle;
 223
 224         /** @var float UNIX timestamp */
 225         protected $lastPing = 0.0;
 226
 227         /** @var int[] Prior mFlags values */
 228         private $priorFlags = [];
 229
 230         /** @var object|string Class name or object With profileIn/profileOut methods */
 231         protected $profiler;
 232         /** @var TransactionProfiler */
 233         protected $trxProfiler;
 234
 235         /**
 236          * Constructor and database handle and attempt to connect to the DB server
 237          *
 238          * IDatabase classes should not be constructed directly in external
 239          * code. Database::factory() should be used instead.
 240          *
 241          * @param array $params Parameters passed from Database::factory()
 242          */
 243         function __construct( array $params ) {
 244                 $server = $params['host'];
 245                 $user = $params['user'];
 246                 $password = $params['password'];
 247                 $dbName = $params['dbname'];
 248
 249                 $this->mSchema = $params['schema'];
 250                 $this->mTablePrefix = $params['tablePrefix'];
 251
 252                 $this->cliMode = $params['cliMode'];
 253                 // Agent name is added to SQL queries in a comment, so make sure it can't break out
 254                 $this->agent = str_replace( '/', '-', $params['agent'] );
 255
 256                 $this->mFlags = $params['flags'];
 257                 if ( $this->mFlags & self::DBO_DEFAULT ) {
 258                         if ( $this->cliMode ) {
 259                                 $this->mFlags &= ~self::DBO_TRX;
 260                         } else {
 261                                 $this->mFlags |= self::DBO_TRX;
 262                         }
 263                 }
 264
 265                 $this->mSessionVars = $params['variables'];
 266
 267                 $this->srvCache = isset( $params['srvCache'] )
 268                         ? $params['srvCache']
 269                         : new HashBagOStuff();
 270
 271                 $this->profiler = $params['profiler'];
 272                 $this->trxProfiler = $params['trxProfiler'];
 273                 $this->connLogger = $params['connLogger'];
 274                 $this->queryLogger = $params['queryLogger'];
 275                 $this->errorLogger = $params['errorLogger'];
 276
 277                 // Set initial dummy domain until open() sets the final DB/prefix
 278                 $this->currentDomain = DatabaseDomain::newUnspecified();
 279
 280                 if ( $user ) {
 281                         $this->open( $server, $user, $password, $dbName );
 282                 } elseif ( $this->requiresDatabaseUser() ) {
 283                         throw new InvalidArgumentException( "No database user provided." );
 284                 }
 285
 286                 // Set the domain object after open() sets the relevant fields
 287                 if ( $this->mDBname != '' ) {
 288                         // Domains with server scope but a table prefix are not used by IDatabase classes
 289                         $this->currentDomain = new DatabaseDomain( $this->mDBname, null, $this->mTablePrefix );
 290                 }
 291         }
 292
 293         /**
 294          * Construct a Database subclass instance given a database type and parameters
 295          *
 296          * This also connects to the database immediately upon object construction
 297          *
 298          * @param string $dbType A possible DB type (sqlite, mysql, postgres)
 299          * @param array $p Parameter map with keys:
 300          *   - host : The hostname of the DB server
 301          *   - user : The name of the database user the client operates under
 302          *   - password : The password for the database user
 303          *   - dbname : The name of the database to use where queries do not specify one.
 304          *      The database must exist or an error might be thrown. Setting this to the empty string
 305          *      will avoid any such errors and make the handle have no implicit database scope. This is
 306          *      useful for queries like SHOW STATUS, CREATE DATABASE, or DROP DATABASE. Note that a
 307          *      "database" in Postgres is rougly equivalent to an entire MySQL server. This the domain
 308          *      in which user names and such are defined, e.g. users are database-specific in Postgres.
 309          *   - schema : The database schema to use (if supported). A "schema" in Postgres is roughly
 310          *      equivalent to a "database" in MySQL. Note that MySQL and SQLite do not use schemas.
 311          *   - tablePrefix : Optional table prefix that is implicitly added on to all table names
 312          *      recognized in queries. This can be used in place of schemas for handle site farms.
 313          *   - flags : Optional bitfield of DBO_* constants that define connection, protocol,
 314          *      buffering, and transaction behavior. It is STRONGLY adviced to leave the DBO_DEFAULT
 315          *      flag in place UNLESS this this database simply acts as a key/value store.
 316          *   - driver: Optional name of a specific DB client driver. For MySQL, there is the old
 317          *      'mysql' driver and the newer 'mysqli' driver.
 318          *   - variables: Optional map of session variables to set after connecting. This can be
 319          *      used to adjust lock timeouts or encoding modes and the like.
 320          *   - connLogger: Optional PSR-3 logger interface instance.
 321          *   - queryLogger: Optional PSR-3 logger interface instance.
 322          *   - profiler: Optional class name or object with profileIn()/profileOut() methods.
 323          *      These will be called in query(), using a simplified version of the SQL that also
 324          *      includes the agent as a SQL comment.
 325          *   - trxProfiler: Optional TransactionProfiler instance.
 326          *   - errorLogger: Optional callback that takes an Exception and logs it.
 327          *   - cliMode: Whether to consider the execution context that of a CLI script.
 328          *   - agent: Optional name used to identify the end-user in query profiling/logging.
 329          *   - srvCache: Optional BagOStuff instance to an APC-style cache.
 330          * @return Database|null If the database driver or extension cannot be found
 331          * @throws InvalidArgumentException If the database driver or extension cannot be found
 332          * @since 1.18
 333          */
 334         final public static function factory( $dbType, $p = [] ) {
 335                 static $canonicalDBTypes = [
 336                         'mysql' => [ 'mysqli', 'mysql' ],
 337                         'postgres' => [],
 338                         'sqlite' => [],
 339                         'oracle' => [],
 340                         'mssql' => [],
 341                 ];
 342                 static $classAliases = [
 343                         'DatabaseMssql' => DatabaseMssql::class,
 344                         'DatabaseMysql' => DatabaseMysql::class,
 345                         'DatabaseMysqli' => DatabaseMysqli::class,
 346                         'DatabaseSqlite' => DatabaseSqlite::class,
 347                         'DatabasePostgres' => DatabasePostgres::class
 348                 ];
 349
 350                 $driver = false;
 351                 $dbType = strtolower( $dbType );
 352                 if ( isset( $canonicalDBTypes[$dbType] ) && $canonicalDBTypes[$dbType] ) {
 353                         $possibleDrivers = $canonicalDBTypes[$dbType];
 354                         if ( !empty( $p['driver'] ) ) {
 355                                 if ( in_array( $p['driver'], $possibleDrivers ) ) {
 356                                         $driver = $p['driver'];
 357                                 } else {
 358                                         throw new InvalidArgumentException( __METHOD__ .
 359                                                 " type '$dbType' does not support driver '{$p['driver']}'" );
 360                                 }
 361                         } else {
 362                                 foreach ( $possibleDrivers as $posDriver ) {
 363                                         if ( extension_loaded( $posDriver ) ) {
 364                                                 $driver = $posDriver;
 365                                                 break;
 366                                         }
 367                                 }
 368                         }
 369                 } else {
 370                         $driver = $dbType;
 371                 }
 372
 373                 if ( $driver === false || $driver === '' ) {
 374                         throw new InvalidArgumentException( __METHOD__ .
 375                                 " no viable database extension found for type '$dbType'" );
 376                 }
 377
 378                 $class = 'Database' . ucfirst( $driver );
 379                 if ( isset( $classAliases[$class] ) ) {
 380                         $class = $classAliases[$class];
 381                 }
 382
 383                 if ( class_exists( $class ) && is_subclass_of( $class, IDatabase::class ) ) {
 384                         // Resolve some defaults for b/c
 385                         $p['host'] = isset( $p['host'] ) ? $p['host'] : false;
 386                         $p['user'] = isset( $p['user'] ) ? $p['user'] : false;
 387                         $p['password'] = isset( $p['password'] ) ? $p['password'] : false;
 388                         $p['dbname'] = isset( $p['dbname'] ) ? $p['dbname'] : false;
 389                         $p['flags'] = isset( $p['flags'] ) ? $p['flags'] : 0;
 390                         $p['variables'] = isset( $p['variables'] ) ? $p['variables'] : [];
 391                         $p['tablePrefix'] = isset( $p['tablePrefix'] ) ? $p['tablePrefix'] : '';
 392                         $p['schema'] = isset( $p['schema'] ) ? $p['schema'] : '';
 393                         $p['cliMode'] = isset( $p['cliMode'] ) ? $p['cliMode'] : ( PHP_SAPI === 'cli' );
 394                         $p['agent'] = isset( $p['agent'] ) ? $p['agent'] : '';
 395                         if ( !isset( $p['connLogger'] ) ) {
 396                                 $p['connLogger'] = new \Psr\Log\NullLogger();
 397                         }
 398                         if ( !isset( $p['queryLogger'] ) ) {
 399                                 $p['queryLogger'] = new \Psr\Log\NullLogger();
 400                         }
 401                         $p['profiler'] = isset( $p['profiler'] ) ? $p['profiler'] : null;
 402                         if ( !isset( $p['trxProfiler'] ) ) {
 403                                 $p['trxProfiler'] = new TransactionProfiler();
 404                         }
 405                         if ( !isset( $p['errorLogger'] ) ) {
 406                                 $p['errorLogger'] = function ( Exception $e ) {
 407                                         trigger_error( get_class( $e ) . ': ' . $e->getMessage(), E_USER_WARNING );
 408                                 };
 409                         }
 410
 411                         $conn = new $class( $p );
 412                 } else {
 413                         $conn = null;
 414                 }
 415
 416                 return $conn;
 417         }
 418
 419         public function setLogger( LoggerInterface $logger ) {
 420                 $this->queryLogger = $logger;
 421         }
 422
 423         public function getServerInfo() {
 424                 return $this->getServerVersion();
 425         }
 426
 427         public function bufferResults( $buffer = null ) {
 428                 $res = !$this->getFlag( self::DBO_NOBUFFER );
 429                 if ( $buffer !== null ) {
 430                         $buffer
 431                                 ? $this->clearFlag( self::DBO_NOBUFFER )
 432                                 : $this->setFlag( self::DBO_NOBUFFER );
 433                 }
 434
 435                 return $res;
 436         }
 437
 438         /**
 439          * Turns on (false) or off (true) the automatic generation and sending
 440          * of a "we're sorry, but there has been a database error" page on
 441          * database errors. Default is on (false). When turned off, the
 442          * code should use lastErrno() and lastError() to handle the
 443          * situation as appropriate.
 444          *
 445          * Do not use this function outside of the Database classes.
 446          *
 447          * @param null|bool $ignoreErrors
 448          * @return bool The previous value of the flag.
 449          */
 450         protected function ignoreErrors( $ignoreErrors = null ) {
 451                 $res = $this->getFlag( self::DBO_IGNORE );
 452                 if ( $ignoreErrors !== null ) {
 453                         $ignoreErrors
 454                                 ? $this->setFlag( self::DBO_IGNORE )
 455                                 : $this->clearFlag( self::DBO_IGNORE );
 456                 }
 457
 458                 return $res;
 459         }
 460
 461         public function trxLevel() {
 462                 return $this->mTrxLevel;
 463         }
 464
 465         public function trxTimestamp() {
 466                 return $this->mTrxLevel ? $this->mTrxTimestamp : null;
 467         }
 468
 469         public function tablePrefix( $prefix = null ) {
 470                 $old = $this->mTablePrefix;
 471                 if ( $prefix !== null ) {
 472                         $this->mTablePrefix = $prefix;
 473                         $this->currentDomain = ( $this->mDBname != '' )
 474                                 ? new DatabaseDomain( $this->mDBname, null, $this->mTablePrefix )
 475                                 : DatabaseDomain::newUnspecified();
 476                 }
 477
 478                 return $old;
 479         }
 480
 481         public function dbSchema( $schema = null ) {
 482                 $old = $this->mSchema;
 483                 if ( $schema !== null ) {
 484                         $this->mSchema = $schema;
 485                 }
 486
 487                 return $old;
 488         }
 489
 490         public function getLBInfo( $name = null ) {
 491                 if ( is_null( $name ) ) {
 492                         return $this->mLBInfo;
 493                 } else {
 494                         if ( array_key_exists( $name, $this->mLBInfo ) ) {
 495                                 return $this->mLBInfo[$name];
 496                         } else {
 497                                 return null;
 498                         }
 499                 }
 500         }
 501
 502         public function setLBInfo( $name, $value = null ) {
 503                 if ( is_null( $value ) ) {
 504                         $this->mLBInfo = $name;
 505                 } else {
 506                         $this->mLBInfo[$name] = $value;
 507                 }
 508         }
 509
 510         public function setLazyMasterHandle( IDatabase $conn ) {
 511                 $this->lazyMasterHandle = $conn;
 512         }
 513
 514         /**
 515          * @return IDatabase|null
 516          * @see setLazyMasterHandle()
 517          * @since 1.27
 518          */
 519         protected function getLazyMasterHandle() {
 520                 return $this->lazyMasterHandle;
 521         }
 522
 523         public function implicitGroupby() {
 524                 return true;
 525         }
 526
 527         public function implicitOrderby() {
 528                 return true;
 529         }
 530
 531         public function lastQuery() {
 532                 return $this->mLastQuery;
 533         }
 534
 535         public function doneWrites() {
 536                 return (bool)$this->mLastWriteTime;
 537         }
 538
 539         public function lastDoneWrites() {
 540                 return $this->mLastWriteTime ?: false;
 541         }
 542
 543         public function writesPending() {
 544                 return $this->mTrxLevel && $this->mTrxDoneWrites;
 545         }
 546
 547         public function writesOrCallbacksPending() {
 548                 return $this->mTrxLevel && (
 549                         $this->mTrxDoneWrites || $this->mTrxIdleCallbacks || $this->mTrxPreCommitCallbacks
 550                 );
 551         }
 552
 553         public function pendingWriteQueryDuration( $type = self::ESTIMATE_TOTAL ) {
 554                 if ( !$this->mTrxLevel ) {
 555                         return false;
 556                 } elseif ( !$this->mTrxDoneWrites ) {
 557                         return 0.0;
 558                 }
 559
 560                 switch ( $type ) {
 561                         case self::ESTIMATE_DB_APPLY:
 562                                 $this->ping( $rtt );
 563                                 $rttAdjTotal = $this->mTrxWriteAdjQueryCount * $rtt;
 564                                 $applyTime = max( $this->mTrxWriteAdjDuration - $rttAdjTotal, 0 );
 565                                 // For omitted queries, make them count as something at least
 566                                 $omitted = $this->mTrxWriteQueryCount - $this->mTrxWriteAdjQueryCount;
 567                                 $applyTime += self::TINY_WRITE_SEC * $omitted;
 568
 569                                 return $applyTime;
 570                         default: // everything
 571                                 return $this->mTrxWriteDuration;
 572                 }
 573         }
 574
 575         public function pendingWriteCallers() {
 576                 return $this->mTrxLevel ? $this->mTrxWriteCallers : [];
 577         }
 578
 579         protected function pendingWriteAndCallbackCallers() {
 580                 if ( !$this->mTrxLevel ) {
 581                         return [];
 582                 }
 583
 584                 $fnames = $this->mTrxWriteCallers;
 585                 foreach ( [
 586                         $this->mTrxIdleCallbacks,
 587                         $this->mTrxPreCommitCallbacks,
 588                         $this->mTrxEndCallbacks
 589                 ] as $callbacks ) {
 590                         foreach ( $callbacks as $callback ) {
 591                                 $fnames[] = $callback[1];
 592                         }
 593                 }
 594
 595                 return $fnames;
 596         }
 597
 598         public function isOpen() {
 599                 return $this->mOpened;
 600         }
 601
 602         public function setFlag( $flag, $remember = self::REMEMBER_NOTHING ) {
 603                 if ( $remember === self::REMEMBER_PRIOR ) {
 604                         array_push( $this->priorFlags, $this->mFlags );
 605                 }
 606                 $this->mFlags |= $flag;
 607         }
 608
 609         public function clearFlag( $flag, $remember = self::REMEMBER_NOTHING ) {
 610                 if ( $remember === self::REMEMBER_PRIOR ) {
 611                         array_push( $this->priorFlags, $this->mFlags );
 612                 }
 613                 $this->mFlags &= ~$flag;
 614         }
 615
 616         public function restoreFlags( $state = self::RESTORE_PRIOR ) {
 617                 if ( !$this->priorFlags ) {
 618                         return;
 619                 }
 620
 621                 if ( $state === self::RESTORE_INITIAL ) {
 622                         $this->mFlags = reset( $this->priorFlags );
 623                         $this->priorFlags = [];
 624                 } else {
 625                         $this->mFlags = array_pop( $this->priorFlags );
 626                 }
 627         }
 628
 629         public function getFlag( $flag ) {
 630                 return !!( $this->mFlags & $flag );
 631         }
 632
 633         /**
 634          * @param string $name Class field name
 635          * @return mixed
 636          * @deprecated Since 1.28
 637          */
 638         public function getProperty( $name ) {
 639                 return $this->$name;
 640         }
 641
 642         public function getDomainID() {
 643                 return $this->currentDomain->getId();
 644         }
 645
 646         final public function getWikiID() {
 647                 return $this->getDomainID();
 648         }
 649
 650         /**
 651          * Get information about an index into an object
 652          * @param string $table Table name
 653          * @param string $index Index name
 654          * @param string $fname Calling function name
 655          * @return mixed Database-specific index description class or false if the index does not exist
 656          */
 657         abstract function indexInfo( $table, $index, $fname = __METHOD__ );
 658
 659         /**
 660          * Wrapper for addslashes()
 661          *
 662          * @param string $s String to be slashed.
 663          * @return string Slashed string.
 664          */
 665         abstract function strencode( $s );
 666
 667         protected function installErrorHandler() {
 668                 $this->mPHPError = false;
 669                 $this->htmlErrors = ini_set( 'html_errors', '0' );
 670                 set_error_handler( [ $this, 'connectionErrorLogger' ] );
 671         }
 672
 673         /**
 674          * @return bool|string
 675          */
 676         protected function restoreErrorHandler() {
 677                 restore_error_handler();
 678                 if ( $this->htmlErrors !== false ) {
 679                         ini_set( 'html_errors', $this->htmlErrors );
 680                 }
 681
 682                 return $this->getLastPHPError();
 683         }
 684
 685         /**
 686          * @return string|bool Last PHP error for this DB (typically connection errors)
 687          */
 688         protected function getLastPHPError() {
 689                 if ( $this->mPHPError ) {
 690                         $error = preg_replace( '!\[<a.*</a>\]!', '', $this->mPHPError );
 691                         $error = preg_replace( '!^.*?:\s?(.*)$!', '$1', $error );
 692
 693                         return $error;
 694                 }
 695
 696                 return false;
 697         }
 698
 699         /**
 700          * This method should not be used outside of Database classes
 701          *
 702          * @param int $errno
 703          * @param string $errstr
 704          */
 705         public function connectionErrorLogger( $errno, $errstr ) {
 706                 $this->mPHPError = $errstr;
 707         }
 708
 709         /**
 710          * Create a log context to pass to PSR-3 logger functions.
 711          *
 712          * @param array $extras Additional data to add to context
 713          * @return array
 714          */
 715         protected function getLogContext( array $extras = [] ) {
 716                 return array_merge(
 717                         [
 718                                 'db_server' => $this->mServer,
 719                                 'db_name' => $this->mDBname,
 720                                 'db_user' => $this->mUser,
 721                         ],
 722                         $extras
 723                 );
 724         }
 725
 726         public function close() {
 727                 if ( $this->mConn ) {
 728                         if ( $this->trxLevel() ) {
 729                                 $this->commit( __METHOD__, self::FLUSHING_INTERNAL );
 730                         }
 731
 732                         $closed = $this->closeConnection();
 733                         $this->mConn = false;
 734                 } elseif ( $this->mTrxIdleCallbacks || $this->mTrxEndCallbacks ) { // sanity
 735                         throw new RuntimeException( "Transaction callbacks still pending." );
 736                 } else {
 737                         $closed = true;
 738                 }
 739                 $this->mOpened = false;
 740
 741                 return $closed;
 742         }
 743
 744         /**
 745          * Make sure isOpen() returns true as a sanity check
 746          *
 747          * @throws DBUnexpectedError
 748          */
 749         protected function assertOpen() {
 750                 if ( !$this->isOpen() ) {
 751                         throw new DBUnexpectedError( $this, "DB connection was already closed." );
 752                 }
 753         }
 754
 755         /**
 756          * Closes underlying database connection
 757          * @since 1.20
 758          * @return bool Whether connection was closed successfully
 759          */
 760         abstract protected function closeConnection();
 761
 762         public function reportConnectionError( $error = 'Unknown error' ) {
 763                 $myError = $this->lastError();
 764                 if ( $myError ) {
 765                         $error = $myError;
 766                 }
 767
 768                 # New method
 769                 throw new DBConnectionError( $this, $error );
 770         }
 771
 772         /**
 773          * The DBMS-dependent part of query()
 774          *
 775          * @param string $sql SQL query.
 776          * @return ResultWrapper|bool Result object to feed to fetchObject,
 777          *   fetchRow, ...; or false on failure
 778          */
 779         abstract protected function doQuery( $sql );
 780
 781         /**
 782          * Determine whether a query writes to the DB.
 783          * Should return true if unsure.
 784          *
 785          * @param string $sql
 786          * @return bool
 787          */
 788         protected function isWriteQuery( $sql ) {
 789                 return !preg_match(
 790                         '/^(?:SELECT|BEGIN|ROLLBACK|COMMIT|SET|SHOW|EXPLAIN|\(SELECT)\b/i', $sql );
 791         }
 792
 793         /**
 794          * @param $sql
 795          * @return string|null
 796          */
 797         protected function getQueryVerb( $sql ) {
 798                 return preg_match( '/^\s*([a-z]+)/i', $sql, $m ) ? strtoupper( $m[1] ) : null;
 799         }
 800
 801         /**
 802          * Determine whether a SQL statement is sensitive to isolation level.
 803          * A SQL statement is considered transactable if its result could vary
 804          * depending on the transaction isolation level. Operational commands
 805          * such as 'SET' and 'SHOW' are not considered to be transactable.
 806          *
 807          * @param string $sql
 808          * @return bool
 809          */
 810         protected function isTransactableQuery( $sql ) {
 811                 return !in_array(
 812                         $this->getQueryVerb( $sql ),
 813                         [ 'BEGIN', 'COMMIT', 'ROLLBACK', 'SHOW', 'SET', 'CREATE', 'ALTER' ],
 814                         true
 815                 );
 816         }
 817
 818         /**
 819          * @param string $sql A SQL query
 820          * @return bool Whether $sql is SQL for creating/dropping a new TEMPORARY table
 821          */
 822         protected function registerTempTableOperation( $sql ) {
 823                 if ( preg_match(
 824                         '/^CREATE\s+TEMPORARY\s+TABLE\s+(?:IF\s+NOT\s+EXISTS\s+)?[`"\']?(\w+)[`"\']?/i',
 825                         $sql,
 826                         $matches
 827                 ) ) {
 828                         $this->mSessionTempTables[$matches[1]] = 1;
 829
 830                         return true;
 831                 } elseif ( preg_match(
 832                         '/^DROP\s+(?:TEMPORARY\s+)?TABLE\s+(?:IF\s+EXISTS\s+)?[`"\']?(\w+)[`"\']?/i',
 833                         $sql,
 834                         $matches
 835                 ) ) {
 836                         $isTemp = isset( $this->mSessionTempTables[$matches[1]] );
 837                         unset( $this->mSessionTempTables[$matches[1]] );
 838
 839                         return $isTemp;
 840                 } elseif ( preg_match(
 841                         '/^(?:INSERT\s+(?:\w+\s+)?INTO|UPDATE|DELETE\s+FROM)\s+[`"\']?(\w+)[`"\']?/i',
 842                         $sql,
 843                         $matches
 844                 ) ) {
 845                         return isset( $this->mSessionTempTables[$matches[1]] );
 846                 }
 847
 848                 return false;
 849         }
 850
 851         public function query( $sql, $fname = __METHOD__, $tempIgnore = false ) {
 852                 $priorWritesPending = $this->writesOrCallbacksPending();
 853                 $this->mLastQuery = $sql;
 854
 855                 $isWrite = $this->isWriteQuery( $sql ) && !$this->registerTempTableOperation( $sql );
 856                 if ( $isWrite ) {
 857                         $reason = $this->getReadOnlyReason();
 858                         if ( $reason !== false ) {
 859                                 throw new DBReadOnlyError( $this, "Database is read-only: $reason" );
 860                         }
 861                         # Set a flag indicating that writes have been done
 862                         $this->mLastWriteTime = microtime( true );
 863                 }
 864
 865                 // Add trace comment to the begin of the sql string, right after the operator.
 866                 // Or, for one-word queries (like "BEGIN" or COMMIT") add it to the end (T44598)
 867                 $commentedSql = preg_replace( '/\s|$/', " /* $fname {$this->agent} */ ", $sql, 1 );
 868
 869                 # Start implicit transactions that wrap the request if DBO_TRX is enabled
 870                 if ( !$this->mTrxLevel && $this->getFlag( self::DBO_TRX )
 871                         && $this->isTransactableQuery( $sql )
 872                 ) {
 873                         $this->begin( __METHOD__ . " ($fname)", self::TRANSACTION_INTERNAL );
 874                         $this->mTrxAutomatic = true;
 875                 }
 876
 877                 # Keep track of whether the transaction has write queries pending
 878                 if ( $this->mTrxLevel && !$this->mTrxDoneWrites && $isWrite ) {
 879                         $this->mTrxDoneWrites = true;
 880                         $this->trxProfiler->transactionWritingIn(
 881                                 $this->mServer, $this->mDBname, $this->mTrxShortId );
 882                 }
 883
 884                 if ( $this->getFlag( self::DBO_DEBUG ) ) {
 885                         $this->queryLogger->debug( "{$this->mDBname} {$commentedSql}" );
 886                 }
 887
 888                 # Avoid fatals if close() was called
 889                 $this->assertOpen();
 890
 891                 # Send the query to the server
 892                 $ret = $this->doProfiledQuery( $sql, $commentedSql, $isWrite, $fname );
 893
 894                 # Try reconnecting if the connection was lost
 895                 if ( false === $ret && $this->wasErrorReissuable() ) {
 896                         $recoverable = $this->canRecoverFromDisconnect( $sql, $priorWritesPending );
 897                         # Stash the last error values before anything might clear them
 898                         $lastError = $this->lastError();
 899                         $lastErrno = $this->lastErrno();
 900                         # Update state tracking to reflect transaction loss due to disconnection
 901                         $this->handleSessionLoss();
 902                         if ( $this->reconnect() ) {
 903                                 $msg = __METHOD__ . ": lost connection to {$this->getServer()}; reconnected";
 904                                 $this->connLogger->warning( $msg );
 905                                 $this->queryLogger->warning(
 906                                         "$msg:\n" . ( new RuntimeException() )->getTraceAsString() );
 907
 908                                 if ( !$recoverable ) {
 909                                         # Callers may catch the exception and continue to use the DB
 910                                         $this->reportQueryError( $lastError, $lastErrno, $sql, $fname );
 911                                 } else {
 912                                         # Should be safe to silently retry the query
 913                                         $ret = $this->doProfiledQuery( $sql, $commentedSql, $isWrite, $fname );
 914                                 }
 915                         } else {
 916                                 $msg = __METHOD__ . ": lost connection to {$this->getServer()} permanently";
 917                                 $this->connLogger->error( $msg );
 918                         }
 919                 }
 920
 921                 if ( false === $ret ) {
 922                         # Deadlocks cause the entire transaction to abort, not just the statement.
 923                         # https://dev.mysql.com/doc/refman/5.7/en/innodb-error-handling.html
 924                         # https://www.postgresql.org/docs/9.1/static/explicit-locking.html
 925                         if ( $this->wasDeadlock() ) {
 926                                 if ( $this->explicitTrxActive() || $priorWritesPending ) {
 927                                         $tempIgnore = false; // not recoverable
 928                                 }
 929                                 # Update state tracking to reflect transaction loss
 930                                 $this->handleSessionLoss();
 931                         }
 932
 933                         $this->reportQueryError(
 934                                 $this->lastError(), $this->lastErrno(), $sql, $fname, $tempIgnore );
 935                 }
 936
 937                 $res = $this->resultObject( $ret );
 938
 939                 return $res;
 940         }
 941
 942         private function doProfiledQuery( $sql, $commentedSql, $isWrite, $fname ) {
 943                 $isMaster = !is_null( $this->getLBInfo( 'master' ) );
 944                 # generalizeSQL() will probably cut down the query to reasonable
 945                 # logging size most of the time. The substr is really just a sanity check.
 946                 if ( $isMaster ) {
 947                         $queryProf = 'query-m: ' . substr( self::generalizeSQL( $sql ), 0, 255 );
 948                 } else {
 949                         $queryProf = 'query: ' . substr( self::generalizeSQL( $sql ), 0, 255 );
 950                 }
 951
 952                 # Include query transaction state
 953                 $queryProf .= $this->mTrxShortId ? " [TRX#{$this->mTrxShortId}]" : "";
 954
 955                 $startTime = microtime( true );
 956                 if ( $this->profiler ) {
 957                         call_user_func( [ $this->profiler, 'profileIn' ], $queryProf );
 958                 }
 959                 $ret = $this->doQuery( $commentedSql );
 960                 if ( $this->profiler ) {
 961                         call_user_func( [ $this->profiler, 'profileOut' ], $queryProf );
 962                 }
 963                 $queryRuntime = max( microtime( true ) - $startTime, 0.0 );
 964
 965                 unset( $queryProfSection ); // profile out (if set)
 966
 967                 if ( $ret !== false ) {
 968                         $this->lastPing = $startTime;
 969                         if ( $isWrite && $this->mTrxLevel ) {
 970                                 $this->updateTrxWriteQueryTime( $sql, $queryRuntime );
 971                                 $this->mTrxWriteCallers[] = $fname;
 972                         }
 973                 }
 974
 975                 if ( $sql === self::PING_QUERY ) {
 976                         $this->mRTTEstimate = $queryRuntime;
 977                 }
 978
 979                 $this->trxProfiler->recordQueryCompletion(
 980                         $queryProf, $startTime, $isWrite, $this->affectedRows()
 981                 );
 982                 $this->queryLogger->debug( $sql, [
 983                         'method' => $fname,
 984                         'master' => $isMaster,
 985                         'runtime' => $queryRuntime,
 986                 ] );
 987
 988                 return $ret;
 989         }
 990
 991         /**
 992          * Update the estimated run-time of a query, not counting large row lock times
 993          *
 994          * LoadBalancer can be set to rollback transactions that will create huge replication
 995          * lag. It bases this estimate off of pendingWriteQueryDuration(). Certain simple
 996          * queries, like inserting a row can take a long time due to row locking. This method
 997          * uses some simple heuristics to discount those cases.
 998          *
 999          * @param string $sql A SQL write query
1000          * @param float $runtime Total runtime, including RTT
1001          */
1002         private function updateTrxWriteQueryTime( $sql, $runtime ) {
1003                 // Whether this is indicative of replica DB runtime (except for RBR or ws_repl)
1004                 $indicativeOfReplicaRuntime = true;
1005                 if ( $runtime > self::SLOW_WRITE_SEC ) {
1006                         $verb = $this->getQueryVerb( $sql );
1007                         // insert(), upsert(), replace() are fast unless bulky in size or blocked on locks
1008                         if ( $verb === 'INSERT' ) {
1009                                 $indicativeOfReplicaRuntime = $this->affectedRows() > self::SMALL_WRITE_ROWS;
1010                         } elseif ( $verb === 'REPLACE' ) {
1011                                 $indicativeOfReplicaRuntime = $this->affectedRows() > self::SMALL_WRITE_ROWS / 2;
1012                         }
1013                 }
1014
1015                 $this->mTrxWriteDuration += $runtime;
1016                 $this->mTrxWriteQueryCount += 1;
1017                 if ( $indicativeOfReplicaRuntime ) {
1018                         $this->mTrxWriteAdjDuration += $runtime;
1019                         $this->mTrxWriteAdjQueryCount += 1;
1020                 }
1021         }
1022
1023         private function canRecoverFromDisconnect( $sql, $priorWritesPending ) {
1024                 # Transaction dropped; this can mean lost writes, or REPEATABLE-READ snapshots.
1025                 # Dropped connections also mean that named locks are automatically released.
1026                 # Only allow error suppression in autocommit mode or when the lost transaction
1027                 # didn't matter anyway (aside from DBO_TRX snapshot loss).
1028                 if ( $this->mNamedLocksHeld ) {
1029                         return false; // possible critical section violation
1030                 } elseif ( $sql === 'COMMIT' ) {
1031                         return !$priorWritesPending; // nothing written anyway? (T127428)
1032                 } elseif ( $sql === 'ROLLBACK' ) {
1033                         return true; // transaction lost...which is also what was requested :)
1034                 } elseif ( $this->explicitTrxActive() ) {
1035                         return false; // don't drop atomocity
1036                 } elseif ( $priorWritesPending ) {
1037                         return false; // prior writes lost from implicit transaction
1038                 }
1039
1040                 return true;
1041         }
1042
1043         private function handleSessionLoss() {
1044                 $this->mTrxLevel = 0;
1045                 $this->mTrxIdleCallbacks = []; // T67263
1046                 $this->mTrxPreCommitCallbacks = []; // T67263
1047                 $this->mSessionTempTables = [];
1048                 $this->mNamedLocksHeld = [];
1049                 try {
1050                         // Handle callbacks in mTrxEndCallbacks
1051                         $this->runOnTransactionIdleCallbacks( self::TRIGGER_ROLLBACK );
1052                         $this->runTransactionListenerCallbacks( self::TRIGGER_ROLLBACK );
1053                         return null;
1054                 } catch ( Exception $e ) {
1055                         // Already logged; move on...
1056                         return $e;
1057                 }
1058         }
1059
1060         public function reportQueryError( $error, $errno, $sql, $fname, $tempIgnore = false ) {
1061                 if ( $this->ignoreErrors() || $tempIgnore ) {
1062                         $this->queryLogger->debug( "SQL ERROR (ignored): $error\n" );
1063                 } else {
1064                         $sql1line = mb_substr( str_replace( "\n", "\\n", $sql ), 0, 5 * 1024 );
1065                         $this->queryLogger->error(
1066                                 "{fname}\t{db_server}\t{errno}\t{error}\t{sql1line}",
1067                                 $this->getLogContext( [
1068                                         'method' => __METHOD__,
1069                                         'errno' => $errno,
1070                                         'error' => $error,
1071                                         'sql1line' => $sql1line,
1072                                         'fname' => $fname,
1073                                 ] )
1074                         );
1075                         $this->queryLogger->debug( "SQL ERROR: " . $error . "\n" );
1076                         throw new DBQueryError( $this, $error, $errno, $sql, $fname );
1077                 }
1078         }
1079
1080         public function freeResult( $res ) {
1081         }
1082
1083         public function selectField(
1084                 $table, $var, $cond = '', $fname = __METHOD__, $options = []
1085         ) {
1086                 if ( $var === '*' ) { // sanity
1087                         throw new DBUnexpectedError( $this, "Cannot use a * field: got '$var'" );
1088                 }
1089
1090                 if ( !is_array( $options ) ) {
1091                         $options = [ $options ];
1092                 }
1093
1094                 $options['LIMIT'] = 1;
1095
1096                 $res = $this->select( $table, $var, $cond, $fname, $options );
1097                 if ( $res === false || !$this->numRows( $res ) ) {
1098                         return false;
1099                 }
1100
1101                 $row = $this->fetchRow( $res );
1102
1103                 if ( $row !== false ) {
1104                         return reset( $row );
1105                 } else {
1106                         return false;
1107                 }
1108         }
1109
1110         public function selectFieldValues(
1111                 $table, $var, $cond = '', $fname = __METHOD__, $options = [], $join_conds = []
1112         ) {
1113                 if ( $var === '*' ) { // sanity
1114                         throw new DBUnexpectedError( $this, "Cannot use a * field" );
1115                 } elseif ( !is_string( $var ) ) { // sanity
1116                         throw new DBUnexpectedError( $this, "Cannot use an array of fields" );
1117                 }
1118
1119                 if ( !is_array( $options ) ) {
1120                         $options = [ $options ];
1121                 }
1122
1123                 $res = $this->select( $table, $var, $cond, $fname, $options, $join_conds );
1124                 if ( $res === false ) {
1125                         return false;
1126                 }
1127
1128                 $values = [];
1129                 foreach ( $res as $row ) {
1130                         $values[] = $row->$var;
1131                 }
1132
1133                 return $values;
1134         }
1135
1136         /**
1137          * Returns an optional USE INDEX clause to go after the table, and a
1138          * string to go at the end of the query.
1139          *
1140          * @param array $options Associative array of options to be turned into
1141          *   an SQL query, valid keys are listed in the function.
1142          * @return array
1143          * @see Database::select()
1144          */
1145         protected function makeSelectOptions( $options ) {
1146                 $preLimitTail = $postLimitTail = '';
1147                 $startOpts = '';
1148
1149                 $noKeyOptions = [];
1150
1151                 foreach ( $options as $key => $option ) {
1152                         if ( is_numeric( $key ) ) {
1153                                 $noKeyOptions[$option] = true;
1154                         }
1155                 }
1156
1157                 $preLimitTail .= $this->makeGroupByWithHaving( $options );
1158
1159                 $preLimitTail .= $this->makeOrderBy( $options );
1160
1161                 if ( isset( $noKeyOptions['FOR UPDATE'] ) ) {
1162                         $postLimitTail .= ' FOR UPDATE';
1163                 }
1164
1165                 if ( isset( $noKeyOptions['LOCK IN SHARE MODE'] ) ) {
1166                         $postLimitTail .= ' LOCK IN SHARE MODE';
1167                 }
1168
1169                 if ( isset( $noKeyOptions['DISTINCT'] ) || isset( $noKeyOptions['DISTINCTROW'] ) ) {
1170                         $startOpts .= 'DISTINCT';
1171                 }
1172
1173                 # Various MySQL extensions
1174                 if ( isset( $noKeyOptions['STRAIGHT_JOIN'] ) ) {
1175                         $startOpts .= ' /*! STRAIGHT_JOIN */';
1176                 }
1177
1178                 if ( isset( $noKeyOptions['HIGH_PRIORITY'] ) ) {
1179                         $startOpts .= ' HIGH_PRIORITY';
1180                 }
1181
1182                 if ( isset( $noKeyOptions['SQL_BIG_RESULT'] ) ) {
1183                         $startOpts .= ' SQL_BIG_RESULT';
1184                 }
1185
1186                 if ( isset( $noKeyOptions['SQL_BUFFER_RESULT'] ) ) {
1187                         $startOpts .= ' SQL_BUFFER_RESULT';
1188                 }
1189
1190                 if ( isset( $noKeyOptions['SQL_SMALL_RESULT'] ) ) {
1191                         $startOpts .= ' SQL_SMALL_RESULT';
1192                 }
1193
1194                 if ( isset( $noKeyOptions['SQL_CALC_FOUND_ROWS'] ) ) {
1195                         $startOpts .= ' SQL_CALC_FOUND_ROWS';
1196                 }
1197
1198                 if ( isset( $noKeyOptions['SQL_CACHE'] ) ) {
1199                         $startOpts .= ' SQL_CACHE';
1200                 }
1201
1202                 if ( isset( $noKeyOptions['SQL_NO_CACHE'] ) ) {
1203                         $startOpts .= ' SQL_NO_CACHE';
1204                 }
1205
1206                 if ( isset( $options['USE INDEX'] ) && is_string( $options['USE INDEX'] ) ) {
1207                         $useIndex = $this->useIndexClause( $options['USE INDEX'] );
1208                 } else {
1209                         $useIndex = '';
1210                 }
1211                 if ( isset( $options['IGNORE INDEX'] ) && is_string( $options['IGNORE INDEX'] ) ) {
1212                         $ignoreIndex = $this->ignoreIndexClause( $options['IGNORE INDEX'] );
1213                 } else {
1214                         $ignoreIndex = '';
1215                 }
1216
1217                 return [ $startOpts, $useIndex, $preLimitTail, $postLimitTail, $ignoreIndex ];
1218         }
1219
1220         /**
1221          * Returns an optional GROUP BY with an optional HAVING
1222          *
1223          * @param array $options Associative array of options
1224          * @return string
1225          * @see Database::select()
1226          * @since 1.21
1227          */
1228         protected function makeGroupByWithHaving( $options ) {
1229                 $sql = '';
1230                 if ( isset( $options['GROUP BY'] ) ) {
1231                         $gb = is_array( $options['GROUP BY'] )
1232                                 ? implode( ',', $options['GROUP BY'] )
1233                                 : $options['GROUP BY'];
1234                         $sql .= ' GROUP BY ' . $gb;
1235                 }
1236                 if ( isset( $options['HAVING'] ) ) {
1237                         $having = is_array( $options['HAVING'] )
1238                                 ? $this->makeList( $options['HAVING'], self::LIST_AND )
1239                                 : $options['HAVING'];
1240                         $sql .= ' HAVING ' . $having;
1241                 }
1242
1243                 return $sql;
1244         }
1245
1246         /**
1247          * Returns an optional ORDER BY
1248          *
1249          * @param array $options Associative array of options
1250          * @return string
1251          * @see Database::select()
1252          * @since 1.21
1253          */
1254         protected function makeOrderBy( $options ) {
1255                 if ( isset( $options['ORDER BY'] ) ) {
1256                         $ob = is_array( $options['ORDER BY'] )
1257                                 ? implode( ',', $options['ORDER BY'] )
1258                                 : $options['ORDER BY'];
1259
1260                         return ' ORDER BY ' . $ob;
1261                 }
1262
1263                 return '';
1264         }
1265
1266         public function select( $table, $vars, $conds = '', $fname = __METHOD__,
1267                 $options = [], $join_conds = [] ) {
1268                 $sql = $this->selectSQLText( $table, $vars, $conds, $fname, $options, $join_conds );
1269
1270                 return $this->query( $sql, $fname );
1271         }
1272
1273         public function selectSQLText( $table, $vars, $conds = '', $fname = __METHOD__,
1274                 $options = [], $join_conds = []
1275         ) {
1276                 if ( is_array( $vars ) ) {
1277                         $vars = implode( ',', $this->fieldNamesWithAlias( $vars ) );
1278                 }
1279
1280                 $options = (array)$options;
1281                 $useIndexes = ( isset( $options['USE INDEX'] ) && is_array( $options['USE INDEX'] ) )
1282                         ? $options['USE INDEX']
1283                         : [];
1284                 $ignoreIndexes = (
1285                         isset( $options['IGNORE INDEX'] ) &&
1286                         is_array( $options['IGNORE INDEX'] )
1287                 )
1288                         ? $options['IGNORE INDEX']
1289                         : [];
1290
1291                 if ( is_array( $table ) ) {
1292                         $from = ' FROM ' .
1293                                 $this->tableNamesWithIndexClauseOrJOIN(
1294                                         $table, $useIndexes, $ignoreIndexes, $join_conds );
1295                 } elseif ( $table != '' ) {
1296                         if ( $table[0] == ' ' ) {
1297                                 $from = ' FROM ' . $table;
1298                         } else {
1299                                 $from = ' FROM ' .
1300                                         $this->tableNamesWithIndexClauseOrJOIN(
1301                                                 [ $table ], $useIndexes, $ignoreIndexes, [] );
1302                         }
1303                 } else {
1304                         $from = '';
1305                 }
1306
1307                 list( $startOpts, $useIndex, $preLimitTail, $postLimitTail, $ignoreIndex ) =
1308                         $this->makeSelectOptions( $options );
1309
1310                 if ( !empty( $conds ) ) {
1311                         if ( is_array( $conds ) ) {
1312                                 $conds = $this->makeList( $conds, self::LIST_AND );
1313                         }
1314                         $sql = "SELECT $startOpts $vars $from $useIndex $ignoreIndex " .
1315                                 "WHERE $conds $preLimitTail";
1316                 } else {
1317                         $sql = "SELECT $startOpts $vars $from $useIndex $ignoreIndex $preLimitTail";
1318                 }
1319
1320                 if ( isset( $options['LIMIT'] ) ) {
1321                         $sql = $this->limitResult( $sql, $options['LIMIT'],
1322                                 isset( $options['OFFSET'] ) ? $options['OFFSET'] : false );
1323                 }
1324                 $sql = "$sql $postLimitTail";
1325
1326                 if ( isset( $options['EXPLAIN'] ) ) {
1327                         $sql = 'EXPLAIN ' . $sql;
1328                 }
1329
1330                 return $sql;
1331         }
1332
1333         public function selectRow( $table, $vars, $conds, $fname = __METHOD__,
1334                 $options = [], $join_conds = []
1335         ) {
1336                 $options = (array)$options;
1337                 $options['LIMIT'] = 1;
1338                 $res = $this->select( $table, $vars, $conds, $fname, $options, $join_conds );
1339
1340                 if ( $res === false ) {
1341                         return false;
1342                 }
1343
1344                 if ( !$this->numRows( $res ) ) {
1345                         return false;
1346                 }
1347
1348                 $obj = $this->fetchObject( $res );
1349
1350                 return $obj;
1351         }
1352
1353         public function estimateRowCount(
1354                 $table, $vars = '*', $conds = '', $fname = __METHOD__, $options = []
1355         ) {
1356                 $rows = 0;
1357                 $res = $this->select( $table, [ 'rowcount' => 'COUNT(*)' ], $conds, $fname, $options );
1358
1359                 if ( $res ) {
1360                         $row = $this->fetchRow( $res );
1361                         $rows = ( isset( $row['rowcount'] ) ) ? (int)$row['rowcount'] : 0;
1362                 }
1363
1364                 return $rows;
1365         }
1366
1367         public function selectRowCount(
1368                 $tables, $vars = '*', $conds = '', $fname = __METHOD__, $options = [], $join_conds = []
1369         ) {
1370                 $rows = 0;
1371                 $sql = $this->selectSQLText( $tables, '1', $conds, $fname, $options, $join_conds );
1372                 // The identifier quotes is primarily for MSSQL.
1373                 $rowCountCol = $this->addIdentifierQuotes( "rowcount" );
1374                 $tableName = $this->addIdentifierQuotes( "tmp_count" );
1375                 $res = $this->query( "SELECT COUNT(*) AS $rowCountCol FROM ($sql) $tableName", $fname );
1376
1377                 if ( $res ) {
1378                         $row = $this->fetchRow( $res );
1379                         $rows = ( isset( $row['rowcount'] ) ) ? (int)$row['rowcount'] : 0;
1380                 }
1381
1382                 return $rows;
1383         }
1384
1385         /**
1386          * Removes most variables from an SQL query and replaces them with X or N for numbers.
1387          * It's only slightly flawed. Don't use for anything important.
1388          *
1389          * @param string $sql A SQL Query
1390          *
1391          * @return string
1392          */
1393         protected static function generalizeSQL( $sql ) {
1394                 # This does the same as the regexp below would do, but in such a way
1395                 # as to avoid crashing php on some large strings.
1396                 # $sql = preg_replace( "/'([^\\\\']|\\\\.)*'|\"([^\\\\\"]|\\\\.)*\"/", "'X'", $sql );
1397
1398                 $sql = str_replace( "\\\\", '', $sql );
1399                 $sql = str_replace( "\\'", '', $sql );
1400                 $sql = str_replace( "\\\"", '', $sql );
1401                 $sql = preg_replace( "/'.*'/s", "'X'", $sql );
1402                 $sql = preg_replace( '/".*"/s', "'X'", $sql );
1403
1404                 # All newlines, tabs, etc replaced by single space
1405                 $sql = preg_replace( '/\s+/', ' ', $sql );
1406
1407                 # All numbers => N,
1408                 # except the ones surrounded by characters, e.g. l10n
1409                 $sql = preg_replace( '/-?\d+(,-?\d+)+/s', 'N,...,N', $sql );
1410                 $sql = preg_replace( '/(?<![a-zA-Z])-?\d+(?![a-zA-Z])/s', 'N', $sql );
1411
1412                 return $sql;
1413         }
1414
1415         public function fieldExists( $table, $field, $fname = __METHOD__ ) {
1416                 $info = $this->fieldInfo( $table, $field );
1417
1418                 return (bool)$info;
1419         }
1420
1421         public function indexExists( $table, $index, $fname = __METHOD__ ) {
1422                 if ( !$this->tableExists( $table ) ) {
1423                         return null;
1424                 }
1425
1426                 $info = $this->indexInfo( $table, $index, $fname );
1427                 if ( is_null( $info ) ) {
1428                         return null;
1429                 } else {
1430                         return $info !== false;
1431                 }
1432         }
1433
1434         public function tableExists( $table, $fname = __METHOD__ ) {
1435                 $tableRaw = $this->tableName( $table, 'raw' );
1436                 if ( isset( $this->mSessionTempTables[$tableRaw] ) ) {
1437                         return true; // already known to exist
1438                 }
1439
1440                 $table = $this->tableName( $table );
1441                 $ignoreErrors = true;
1442                 $res = $this->query( "SELECT 1 FROM $table LIMIT 1", $fname, $ignoreErrors );
1443
1444                 return (bool)$res;
1445         }
1446
1447         public function indexUnique( $table, $index ) {
1448                 $indexInfo = $this->indexInfo( $table, $index );
1449
1450                 if ( !$indexInfo ) {
1451                         return null;
1452                 }
1453
1454                 return !$indexInfo[0]->Non_unique;
1455         }
1456
1457         /**
1458          * Helper for Database::insert().
1459          *
1460          * @param array $options
1461          * @return string
1462          */
1463         protected function makeInsertOptions( $options ) {
1464                 return implode( ' ', $options );
1465         }
1466
1467         public function insert( $table, $a, $fname = __METHOD__, $options = [] ) {
1468                 # No rows to insert, easy just return now
1469                 if ( !count( $a ) ) {
1470                         return true;
1471                 }
1472
1473                 $table = $this->tableName( $table );
1474
1475                 if ( !is_array( $options ) ) {
1476                         $options = [ $options ];
1477                 }
1478
1479                 $fh = null;
1480                 if ( isset( $options['fileHandle'] ) ) {
1481                         $fh = $options['fileHandle'];
1482                 }
1483                 $options = $this->makeInsertOptions( $options );
1484
1485                 if ( isset( $a[0] ) && is_array( $a[0] ) ) {
1486                         $multi = true;
1487                         $keys = array_keys( $a[0] );
1488                 } else {
1489                         $multi = false;
1490                         $keys = array_keys( $a );
1491                 }
1492
1493                 $sql = 'INSERT ' . $options .
1494                         " INTO $table (" . implode( ',', $keys ) . ') VALUES ';
1495
1496                 if ( $multi ) {
1497                         $first = true;
1498                         foreach ( $a as $row ) {
1499                                 if ( $first ) {
1500                                         $first = false;
1501                                 } else {
1502                                         $sql .= ',';
1503                                 }
1504                                 $sql .= '(' . $this->makeList( $row ) . ')';
1505                         }
1506                 } else {
1507                         $sql .= '(' . $this->makeList( $a ) . ')';
1508                 }
1509
1510                 if ( $fh !== null && false === fwrite( $fh, $sql ) ) {
1511                         return false;
1512                 } elseif ( $fh !== null ) {
1513                         return true;
1514                 }
1515
1516                 return (bool)$this->query( $sql, $fname );
1517         }
1518
1519         /**
1520          * Make UPDATE options array for Database::makeUpdateOptions
1521          *
1522          * @param array $options
1523          * @return array
1524          */
1525         protected function makeUpdateOptionsArray( $options ) {
1526                 if ( !is_array( $options ) ) {
1527                         $options = [ $options ];
1528                 }
1529
1530                 $opts = [];
1531
1532                 if ( in_array( 'IGNORE', $options ) ) {
1533                         $opts[] = 'IGNORE';
1534                 }
1535
1536                 return $opts;
1537         }
1538
1539         /**
1540          * Make UPDATE options for the Database::update function
1541          *
1542          * @param array $options The options passed to Database::update
1543          * @return string
1544          */
1545         protected function makeUpdateOptions( $options ) {
1546                 $opts = $this->makeUpdateOptionsArray( $options );
1547
1548                 return implode( ' ', $opts );
1549         }
1550
1551         public function update( $table, $values, $conds, $fname = __METHOD__, $options = [] ) {
1552                 $table = $this->tableName( $table );
1553                 $opts = $this->makeUpdateOptions( $options );
1554                 $sql = "UPDATE $opts $table SET " . $this->makeList( $values, self::LIST_SET );
1555
1556                 if ( $conds !== [] && $conds !== '*' ) {
1557                         $sql .= " WHERE " . $this->makeList( $conds, self::LIST_AND );
1558                 }
1559
1560                 return (bool)$this->query( $sql, $fname );
1561         }
1562
1563         public function makeList( $a, $mode = self::LIST_COMMA ) {
1564                 if ( !is_array( $a ) ) {
1565                         throw new DBUnexpectedError( $this, __METHOD__ . ' called with incorrect parameters' );
1566                 }
1567
1568                 $first = true;
1569                 $list = '';
1570
1571                 foreach ( $a as $field => $value ) {
1572                         if ( !$first ) {
1573                                 if ( $mode == self::LIST_AND ) {
1574                                         $list .= ' AND ';
1575                                 } elseif ( $mode == self::LIST_OR ) {
1576                                         $list .= ' OR ';
1577                                 } else {
1578                                         $list .= ',';
1579                                 }
1580                         } else {
1581                                 $first = false;
1582                         }
1583
1584                         if ( ( $mode == self::LIST_AND || $mode == self::LIST_OR ) && is_numeric( $field ) ) {
1585                                 $list .= "($value)";
1586                         } elseif ( $mode == self::LIST_SET && is_numeric( $field ) ) {
1587                                 $list .= "$value";
1588                         } elseif (
1589                                 ( $mode == self::LIST_AND || $mode == self::LIST_OR ) && is_array( $value )
1590                         ) {
1591                                 // Remove null from array to be handled separately if found
1592                                 $includeNull = false;
1593                                 foreach ( array_keys( $value, null, true ) as $nullKey ) {
1594                                         $includeNull = true;
1595                                         unset( $value[$nullKey] );
1596                                 }
1597                                 if ( count( $value ) == 0 && !$includeNull ) {
1598                                         throw new InvalidArgumentException(
1599                                                 __METHOD__ . ": empty input for field $field" );
1600                                 } elseif ( count( $value ) == 0 ) {
1601                                         // only check if $field is null
1602                                         $list .= "$field IS NULL";
1603                                 } else {
1604                                         // IN clause contains at least one valid element
1605                                         if ( $includeNull ) {
1606                                                 // Group subconditions to ensure correct precedence
1607                                                 $list .= '(';
1608                                         }
1609                                         if ( count( $value ) == 1 ) {
1610                                                 // Special-case single values, as IN isn't terribly efficient
1611                                                 // Don't necessarily assume the single key is 0; we don't
1612                                                 // enforce linear numeric ordering on other arrays here.
1613                                                 $value = array_values( $value )[0];
1614                                                 $list .= $field . " = " . $this->addQuotes( $value );
1615                                         } else {
1616                                                 $list .= $field . " IN (" . $this->makeList( $value ) . ") ";
1617                                         }
1618                                         // if null present in array, append IS NULL
1619                                         if ( $includeNull ) {
1620                                                 $list .= " OR $field IS NULL)";
1621                                         }
1622                                 }
1623                         } elseif ( $value === null ) {
1624                                 if ( $mode == self::LIST_AND || $mode == self::LIST_OR ) {
1625                                         $list .= "$field IS ";
1626                                 } elseif ( $mode == self::LIST_SET ) {
1627                                         $list .= "$field = ";
1628                                 }
1629                                 $list .= 'NULL';
1630                         } else {
1631                                 if (
1632                                         $mode == self::LIST_AND || $mode == self::LIST_OR || $mode == self::LIST_SET
1633                                 ) {
1634                                         $list .= "$field = ";
1635                                 }
1636                                 $list .= $mode == self::LIST_NAMES ? $value : $this->addQuotes( $value );
1637                         }
1638                 }
1639
1640                 return $list;
1641         }
1642
1643         public function makeWhereFrom2d( $data, $baseKey, $subKey ) {
1644                 $conds = [];
1645
1646                 foreach ( $data as $base => $sub ) {
1647                         if ( count( $sub ) ) {
1648                                 $conds[] = $this->makeList(
1649                                         [ $baseKey => $base, $subKey => array_keys( $sub ) ],
1650                                         self::LIST_AND );
1651                         }
1652                 }
1653
1654                 if ( $conds ) {
1655                         return $this->makeList( $conds, self::LIST_OR );
1656                 } else {
1657                         // Nothing to search for...
1658                         return false;
1659                 }
1660         }
1661
1662         public function aggregateValue( $valuedata, $valuename = 'value' ) {
1663                 return $valuename;
1664         }
1665
1666         public function bitNot( $field ) {
1667                 return "(~$field)";
1668         }
1669
1670         public function bitAnd( $fieldLeft, $fieldRight ) {
1671                 return "($fieldLeft & $fieldRight)";
1672         }
1673
1674         public function bitOr( $fieldLeft, $fieldRight ) {
1675                 return "($fieldLeft | $fieldRight)";
1676         }
1677
1678         public function buildConcat( $stringList ) {
1679                 return 'CONCAT(' . implode( ',', $stringList ) . ')';
1680         }
1681
1682         public function buildGroupConcatField(
1683                 $delim, $table, $field, $conds = '', $join_conds = []
1684         ) {
1685                 $fld = "GROUP_CONCAT($field SEPARATOR " . $this->addQuotes( $delim ) . ')';
1686
1687                 return '(' . $this->selectSQLText( $table, $fld, $conds, null, [], $join_conds ) . ')';
1688         }
1689
1690         public function buildStringCast( $field ) {
1691                 return $field;
1692         }
1693
1694         public function selectDB( $db ) {
1695                 # Stub. Shouldn't cause serious problems if it's not overridden, but
1696                 # if your database engine supports a concept similar to MySQL's
1697                 # databases you may as well.
1698                 $this->mDBname = $db;
1699
1700                 return true;
1701         }
1702
1703         public function getDBname() {
1704                 return $this->mDBname;
1705         }
1706
1707         public function getServer() {
1708                 return $this->mServer;
1709         }
1710
1711         public function tableName( $name, $format = 'quoted' ) {
1712                 # Skip the entire process when we have a string quoted on both ends.
1713                 # Note that we check the end so that we will still quote any use of
1714                 # use of `database`.table. But won't break things if someone wants
1715                 # to query a database table with a dot in the name.
1716                 if ( $this->isQuotedIdentifier( $name ) ) {
1717                         return $name;
1718                 }
1719
1720                 # Lets test for any bits of text that should never show up in a table
1721                 # name. Basically anything like JOIN or ON which are actually part of
1722                 # SQL queries, but may end up inside of the table value to combine
1723                 # sql. Such as how the API is doing.
1724                 # Note that we use a whitespace test rather than a \b test to avoid
1725                 # any remote case where a word like on may be inside of a table name
1726                 # surrounded by symbols which may be considered word breaks.
1727                 if ( preg_match( '/(^|\s)(DISTINCT|JOIN|ON|AS)(\s|$)/i', $name ) !== 0 ) {
1728                         return $name;
1729                 }
1730
1731                 # Split database and table into proper variables.
1732                 # We reverse the explode so that database.table and table both output
1733                 # the correct table.
1734                 $dbDetails = explode( '.', $name, 3 );
1735                 if ( count( $dbDetails ) == 3 ) {
1736                         list( $database, $schema, $table ) = $dbDetails;
1737                         # We don't want any prefix added in this case
1738                         $prefix = '';
1739                 } elseif ( count( $dbDetails ) == 2 ) {
1740                         list( $database, $table ) = $dbDetails;
1741                         # We don't want any prefix added in this case
1742                         $prefix = '';
1743                         # In dbs that support it, $database may actually be the schema
1744                         # but that doesn't affect any of the functionality here
1745                         $schema = '';
1746                 } else {
1747                         list( $table ) = $dbDetails;
1748                         if ( isset( $this->tableAliases[$table] ) ) {
1749                                 $database = $this->tableAliases[$table]['dbname'];
1750                                 $schema = is_string( $this->tableAliases[$table]['schema'] )
1751                                         ? $this->tableAliases[$table]['schema']
1752                                         : $this->mSchema;
1753                                 $prefix = is_string( $this->tableAliases[$table]['prefix'] )
1754                                         ? $this->tableAliases[$table]['prefix']
1755                                         : $this->mTablePrefix;
1756                         } else {
1757                                 $database = '';
1758                                 $schema = $this->mSchema; # Default schema
1759                                 $prefix = $this->mTablePrefix; # Default prefix
1760                         }
1761                 }
1762
1763                 # Quote $table and apply the prefix if not quoted.
1764                 # $tableName might be empty if this is called from Database::replaceVars()
1765                 $tableName = "{$prefix}{$table}";
1766                 if ( $format === 'quoted'
1767                         && !$this->isQuotedIdentifier( $tableName )
1768                         && $tableName !== ''
1769                 ) {
1770                         $tableName = $this->addIdentifierQuotes( $tableName );
1771                 }
1772
1773                 # Quote $schema and $database and merge them with the table name if needed
1774                 $tableName = $this->prependDatabaseOrSchema( $schema, $tableName, $format );
1775                 $tableName = $this->prependDatabaseOrSchema( $database, $tableName, $format );
1776
1777                 return $tableName;
1778         }
1779
1780         /**
1781          * @param string|null $namespace Database or schema
1782          * @param string $relation Name of table, view, sequence, etc...
1783          * @param string $format One of (raw, quoted)
1784          * @return string Relation name with quoted and merged $namespace as needed
1785          */
1786         private function prependDatabaseOrSchema( $namespace, $relation, $format ) {
1787                 if ( strlen( $namespace ) ) {
1788                         if ( $format === 'quoted' && !$this->isQuotedIdentifier( $namespace ) ) {
1789                                 $namespace = $this->addIdentifierQuotes( $namespace );
1790                         }
1791                         $relation = $namespace . '.' . $relation;
1792                 }
1793
1794                 return $relation;
1795         }
1796
1797         public function tableNames() {
1798                 $inArray = func_get_args();
1799                 $retVal = [];
1800
1801                 foreach ( $inArray as $name ) {
1802                         $retVal[$name] = $this->tableName( $name );
1803                 }
1804
1805                 return $retVal;
1806         }
1807
1808         public function tableNamesN() {
1809                 $inArray = func_get_args();
1810                 $retVal = [];
1811
1812                 foreach ( $inArray as $name ) {
1813                         $retVal[] = $this->tableName( $name );
1814                 }
1815
1816                 return $retVal;
1817         }
1818
1819         /**
1820          * Get an aliased table name
1821          * e.g. tableName AS newTableName
1822          *
1823          * @param string $name Table name, see tableName()
1824          * @param string|bool $alias Alias (optional)
1825          * @return string SQL name for aliased table. Will not alias a table to its own name
1826          */
1827         protected function tableNameWithAlias( $name, $alias = false ) {
1828                 if ( !$alias || $alias == $name ) {
1829                         return $this->tableName( $name );
1830                 } else {
1831                         return $this->tableName( $name ) . ' ' . $this->addIdentifierQuotes( $alias );
1832                 }
1833         }
1834
1835         /**
1836          * Gets an array of aliased table names
1837          *
1838          * @param array $tables [ [alias] => table ]
1839          * @return string[] See tableNameWithAlias()
1840          */
1841         protected function tableNamesWithAlias( $tables ) {
1842                 $retval = [];
1843                 foreach ( $tables as $alias => $table ) {
1844                         if ( is_numeric( $alias ) ) {
1845                                 $alias = $table;
1846                         }
1847                         $retval[] = $this->tableNameWithAlias( $table, $alias );
1848                 }
1849
1850                 return $retval;
1851         }
1852
1853         /**
1854          * Get an aliased field name
1855          * e.g. fieldName AS newFieldName
1856          *
1857          * @param string $name Field name
1858          * @param string|bool $alias Alias (optional)
1859          * @return string SQL name for aliased field. Will not alias a field to its own name
1860          */
1861         protected function fieldNameWithAlias( $name, $alias = false ) {
1862                 if ( !$alias || (string)$alias === (string)$name ) {
1863                         return $name;
1864                 } else {
1865                         return $name . ' AS ' . $this->addIdentifierQuotes( $alias ); // PostgreSQL needs AS
1866                 }
1867         }
1868
1869         /**
1870          * Gets an array of aliased field names
1871          *
1872          * @param array $fields [ [alias] => field ]
1873          * @return string[] See fieldNameWithAlias()
1874          */
1875         protected function fieldNamesWithAlias( $fields ) {
1876                 $retval = [];
1877                 foreach ( $fields as $alias => $field ) {
1878                         if ( is_numeric( $alias ) ) {
1879                                 $alias = $field;
1880                         }
1881                         $retval[] = $this->fieldNameWithAlias( $field, $alias );
1882                 }
1883
1884                 return $retval;
1885         }
1886
1887         /**
1888          * Get the aliased table name clause for a FROM clause
1889          * which might have a JOIN and/or USE INDEX or IGNORE INDEX clause
1890          *
1891          * @param array $tables ( [alias] => table )
1892          * @param array $use_index Same as for select()
1893          * @param array $ignore_index Same as for select()
1894          * @param array $join_conds Same as for select()
1895          * @return string
1896          */
1897         protected function tableNamesWithIndexClauseOrJOIN(
1898                 $tables, $use_index = [], $ignore_index = [], $join_conds = []
1899         ) {
1900                 $ret = [];
1901                 $retJOIN = [];
1902                 $use_index = (array)$use_index;
1903                 $ignore_index = (array)$ignore_index;
1904                 $join_conds = (array)$join_conds;
1905
1906                 foreach ( $tables as $alias => $table ) {
1907                         if ( !is_string( $alias ) ) {
1908                                 // No alias? Set it equal to the table name
1909                                 $alias = $table;
1910                         }
1911                         // Is there a JOIN clause for this table?
1912                         if ( isset( $join_conds[$alias] ) ) {
1913                                 list( $joinType, $conds ) = $join_conds[$alias];
1914                                 $tableClause = $joinType;
1915                                 $tableClause .= ' ' . $this->tableNameWithAlias( $table, $alias );
1916                                 if ( isset( $use_index[$alias] ) ) { // has USE INDEX?
1917                                         $use = $this->useIndexClause( implode( ',', (array)$use_index[$alias] ) );
1918                                         if ( $use != '' ) {
1919                                                 $tableClause .= ' ' . $use;
1920                                         }
1921                                 }
1922                                 if ( isset( $ignore_index[$alias] ) ) { // has IGNORE INDEX?
1923                                         $ignore = $this->ignoreIndexClause(
1924                                                 implode( ',', (array)$ignore_index[$alias] ) );
1925                                         if ( $ignore != '' ) {
1926                                                 $tableClause .= ' ' . $ignore;
1927                                         }
1928                                 }
1929                                 $on = $this->makeList( (array)$conds, self::LIST_AND );
1930                                 if ( $on != '' ) {
1931                                         $tableClause .= ' ON (' . $on . ')';
1932                                 }
1933
1934                                 $retJOIN[] = $tableClause;
1935                         } elseif ( isset( $use_index[$alias] ) ) {
1936                                 // Is there an INDEX clause for this table?
1937                                 $tableClause = $this->tableNameWithAlias( $table, $alias );
1938                                 $tableClause .= ' ' . $this->useIndexClause(
1939                                                 implode( ',', (array)$use_index[$alias] )
1940                                         );
1941
1942                                 $ret[] = $tableClause;
1943                         } elseif ( isset( $ignore_index[$alias] ) ) {
1944                                 // Is there an INDEX clause for this table?
1945                                 $tableClause = $this->tableNameWithAlias( $table, $alias );
1946                                 $tableClause .= ' ' . $this->ignoreIndexClause(
1947                                                 implode( ',', (array)$ignore_index[$alias] )
1948                                         );
1949
1950                                 $ret[] = $tableClause;
1951                         } else {
1952                                 $tableClause = $this->tableNameWithAlias( $table, $alias );
1953
1954                                 $ret[] = $tableClause;
1955                         }
1956                 }
1957
1958                 // We can't separate explicit JOIN clauses with ',', use ' ' for those
1959                 $implicitJoins = !empty( $ret ) ? implode( ',', $ret ) : "";
1960                 $explicitJoins = !empty( $retJOIN ) ? implode( ' ', $retJOIN ) : "";
1961
1962                 // Compile our final table clause
1963                 return implode( ' ', [ $implicitJoins, $explicitJoins ] );
1964         }
1965
1966         /**
1967          * Allows for index remapping in queries where this is not consistent across DBMS
1968          *
1969          * @param string $index
1970          * @return string
1971          */
1972         protected function indexName( $index ) {
1973                 return $index;
1974         }
1975
1976         public function addQuotes( $s ) {
1977                 if ( $s instanceof Blob ) {
1978                         $s = $s->fetch();
1979                 }
1980                 if ( $s === null ) {
1981                         return 'NULL';
1982                 } elseif ( is_bool( $s ) ) {
1983                         return (int)$s;
1984                 } else {
1985                         # This will also quote numeric values. This should be harmless,
1986                         # and protects against weird problems that occur when they really
1987                         # _are_ strings such as article titles and string->number->string
1988                         # conversion is not 1:1.
1989                         return "'" . $this->strencode( $s ) . "'";
1990                 }
1991         }
1992
1993         /**
1994          * Quotes an identifier using `backticks` or "double quotes" depending on the database type.
1995          * MySQL uses `backticks` while basically everything else uses double quotes.
1996          * Since MySQL is the odd one out here the double quotes are our generic
1997          * and we implement backticks in DatabaseMysql.
1998          *
1999          * @param string $s
2000          * @return string
2001          */
2002         public function addIdentifierQuotes( $s ) {
2003                 return '"' . str_replace( '"', '""', $s ) . '"';
2004         }
2005
2006         /**
2007          * Returns if the given identifier looks quoted or not according to
2008          * the database convention for quoting identifiers .
2009          *
2010          * @note Do not use this to determine if untrusted input is safe.
2011          *   A malicious user can trick this function.
2012          * @param string $name
2013          * @return bool
2014          */
2015         public function isQuotedIdentifier( $name ) {
2016                 return $name[0] == '"' && substr( $name, -1, 1 ) == '"';
2017         }
2018
2019         /**
2020          * @param string $s
2021          * @return string
2022          */
2023         protected function escapeLikeInternal( $s, $escapeChar = '`' ) {
2024                 return str_replace( [ $escapeChar, '%', '_' ],
2025                         [ "{$escapeChar}{$escapeChar}", "{$escapeChar}%", "{$escapeChar}_" ],
2026                         $s );
2027         }
2028
2029         public function buildLike() {
2030                 $params = func_get_args();
2031
2032                 if ( count( $params ) > 0 && is_array( $params[0] ) ) {
2033                         $params = $params[0];
2034                 }
2035
2036                 $s = '';
2037
2038                 // We use ` instead of \ as the default LIKE escape character, since addQuotes()
2039                 // may escape backslashes, creating problems of double escaping. The `
2040                 // character has good cross-DBMS compatibility, avoiding special operators
2041                 // in MS SQL like ^ and %
2042                 $escapeChar = '`';
2043
2044                 foreach ( $params as $value ) {
2045                         if ( $value instanceof LikeMatch ) {
2046                                 $s .= $value->toString();
2047                         } else {
2048                                 $s .= $this->escapeLikeInternal( $value, $escapeChar );
2049                         }
2050                 }
2051
2052                 return ' LIKE ' . $this->addQuotes( $s ) . ' ESCAPE ' . $this->addQuotes( $escapeChar ) . ' ';
2053         }
2054
2055         public function anyChar() {
2056                 return new LikeMatch( '_' );
2057         }
2058
2059         public function anyString() {
2060                 return new LikeMatch( '%' );
2061         }
2062
2063         public function nextSequenceValue( $seqName ) {
2064                 return null;
2065         }
2066
2067         /**
2068          * USE INDEX clause. Unlikely to be useful for anything but MySQL. This
2069          * is only needed because a) MySQL must be as efficient as possible due to
2070          * its use on Wikipedia, and b) MySQL 4.0 is kind of dumb sometimes about
2071          * which index to pick. Anyway, other databases might have different
2072          * indexes on a given table. So don't bother overriding this unless you're
2073          * MySQL.
2074          * @param string $index
2075          * @return string
2076          */
2077         public function useIndexClause( $index ) {
2078                 return '';
2079         }
2080
2081         /**
2082          * IGNORE INDEX clause. Unlikely to be useful for anything but MySQL. This
2083          * is only needed because a) MySQL must be as efficient as possible due to
2084          * its use on Wikipedia, and b) MySQL 4.0 is kind of dumb sometimes about
2085          * which index to pick. Anyway, other databases might have different
2086          * indexes on a given table. So don't bother overriding this unless you're
2087          * MySQL.
2088          * @param string $index
2089          * @return string
2090          */
2091         public function ignoreIndexClause( $index ) {
2092                 return '';
2093         }
2094
2095         public function replace( $table, $uniqueIndexes, $rows, $fname = __METHOD__ ) {
2096                 $quotedTable = $this->tableName( $table );
2097
2098                 if ( count( $rows ) == 0 ) {
2099                         return;
2100                 }
2101
2102                 # Single row case
2103                 if ( !is_array( reset( $rows ) ) ) {
2104                         $rows = [ $rows ];
2105                 }
2106
2107                 // @FXIME: this is not atomic, but a trx would break affectedRows()
2108                 foreach ( $rows as $row ) {
2109                         # Delete rows which collide
2110                         if ( $uniqueIndexes ) {
2111                                 $sql = "DELETE FROM $quotedTable WHERE ";
2112                                 $first = true;
2113                                 foreach ( $uniqueIndexes as $index ) {
2114                                         if ( $first ) {
2115                                                 $first = false;
2116                                                 $sql .= '( ';
2117                                         } else {
2118                                                 $sql .= ' ) OR ( ';
2119                                         }
2120                                         if ( is_array( $index ) ) {
2121                                                 $first2 = true;
2122                                                 foreach ( $index as $col ) {
2123                                                         if ( $first2 ) {
2124                                                                 $first2 = false;
2125                                                         } else {
2126                                                                 $sql .= ' AND ';
2127                                                         }
2128                                                         $sql .= $col . '=' . $this->addQuotes( $row[$col] );
2129                                                 }
2130                                         } else {
2131                                                 $sql .= $index . '=' . $this->addQuotes( $row[$index] );
2132                                         }
2133                                 }
2134                                 $sql .= ' )';
2135                                 $this->query( $sql, $fname );
2136                         }
2137
2138                         # Now insert the row
2139                         $this->insert( $table, $row, $fname );
2140                 }
2141         }
2142
2143         /**
2144          * REPLACE query wrapper for MySQL and SQLite, which have a native REPLACE
2145          * statement.
2146          *
2147          * @param string $table Table name
2148          * @param array|string $rows Row(s) to insert
2149          * @param string $fname Caller function name
2150          *
2151          * @return ResultWrapper
2152          */
2153         protected function nativeReplace( $table, $rows, $fname ) {
2154                 $table = $this->tableName( $table );
2155
2156                 # Single row case
2157                 if ( !is_array( reset( $rows ) ) ) {
2158                         $rows = [ $rows ];
2159                 }
2160
2161                 $sql = "REPLACE INTO $table (" . implode( ',', array_keys( $rows[0] ) ) . ') VALUES ';
2162                 $first = true;
2163
2164                 foreach ( $rows as $row ) {
2165                         if ( $first ) {
2166                                 $first = false;
2167                         } else {
2168                                 $sql .= ',';
2169                         }
2170
2171                         $sql .= '(' . $this->makeList( $row ) . ')';
2172                 }
2173
2174                 return $this->query( $sql, $fname );
2175         }
2176
2177         public function upsert( $table, array $rows, array $uniqueIndexes, array $set,
2178                 $fname = __METHOD__
2179         ) {
2180                 if ( !count( $rows ) ) {
2181                         return true; // nothing to do
2182                 }
2183
2184                 if ( !is_array( reset( $rows ) ) ) {
2185                         $rows = [ $rows ];
2186                 }
2187
2188                 if ( count( $uniqueIndexes ) ) {
2189                         $clauses = []; // list WHERE clauses that each identify a single row
2190                         foreach ( $rows as $row ) {
2191                                 foreach ( $uniqueIndexes as $index ) {
2192                                         $index = is_array( $index ) ? $index : [ $index ]; // columns
2193                                         $rowKey = []; // unique key to this row
2194                                         foreach ( $index as $column ) {
2195                                                 $rowKey[$column] = $row[$column];
2196                                         }
2197                                         $clauses[] = $this->makeList( $rowKey, self::LIST_AND );
2198                                 }
2199                         }
2200                         $where = [ $this->makeList( $clauses, self::LIST_OR ) ];
2201                 } else {
2202                         $where = false;
2203                 }
2204
2205                 $useTrx = !$this->mTrxLevel;
2206                 if ( $useTrx ) {
2207                         $this->begin( $fname, self::TRANSACTION_INTERNAL );
2208                 }
2209                 try {
2210                         # Update any existing conflicting row(s)
2211                         if ( $where !== false ) {
2212                                 $ok = $this->update( $table, $set, $where, $fname );
2213                         } else {
2214                                 $ok = true;
2215                         }
2216                         # Now insert any non-conflicting row(s)
2217                         $ok = $this->insert( $table, $rows, $fname, [ 'IGNORE' ] ) && $ok;
2218                 } catch ( Exception $e ) {
2219                         if ( $useTrx ) {
2220                                 $this->rollback( $fname, self::FLUSHING_INTERNAL );
2221                         }
2222                         throw $e;
2223                 }
2224                 if ( $useTrx ) {
2225                         $this->commit( $fname, self::FLUSHING_INTERNAL );
2226                 }
2227
2228                 return $ok;
2229         }
2230
2231         public function deleteJoin( $delTable, $joinTable, $delVar, $joinVar, $conds,
2232                 $fname = __METHOD__
2233         ) {
2234                 if ( !$conds ) {
2235                         throw new DBUnexpectedError( $this, __METHOD__ . ' called with empty $conds' );
2236                 }
2237
2238                 $delTable = $this->tableName( $delTable );
2239                 $joinTable = $this->tableName( $joinTable );
2240                 $sql = "DELETE FROM $delTable WHERE $delVar IN (SELECT $joinVar FROM $joinTable ";
2241                 if ( $conds != '*' ) {
2242                         $sql .= 'WHERE ' . $this->makeList( $conds, self::LIST_AND );
2243                 }
2244                 $sql .= ')';
2245
2246                 $this->query( $sql, $fname );
2247         }
2248
2249         public function textFieldSize( $table, $field ) {
2250                 $table = $this->tableName( $table );
2251                 $sql = "SHOW COLUMNS FROM $table LIKE \"$field\";";
2252                 $res = $this->query( $sql, __METHOD__ );
2253                 $row = $this->fetchObject( $res );
2254
2255                 $m = [];
2256
2257                 if ( preg_match( '/\((.*)\)/', $row->Type, $m ) ) {
2258                         $size = $m[1];
2259                 } else {
2260                         $size = -1;
2261                 }
2262
2263                 return $size;
2264         }
2265
2266         public function delete( $table, $conds, $fname = __METHOD__ ) {
2267                 if ( !$conds ) {
2268                         throw new DBUnexpectedError( $this, __METHOD__ . ' called with no conditions' );
2269                 }
2270
2271                 $table = $this->tableName( $table );
2272                 $sql = "DELETE FROM $table";
2273
2274                 if ( $conds != '*' ) {
2275                         if ( is_array( $conds ) ) {
2276                                 $conds = $this->makeList( $conds, self::LIST_AND );
2277                         }
2278                         $sql .= ' WHERE ' . $conds;
2279                 }
2280
2281                 return $this->query( $sql, $fname );
2282         }
2283
2284         public function insertSelect(
2285                 $destTable, $srcTable, $varMap, $conds,
2286                 $fname = __METHOD__, $insertOptions = [], $selectOptions = []
2287         ) {
2288                 if ( $this->cliMode ) {
2289                         // For massive migrations with downtime, we don't want to select everything
2290                         // into memory and OOM, so do all this native on the server side if possible.
2291                         return $this->nativeInsertSelect(
2292                                 $destTable,
2293                                 $srcTable,
2294                                 $varMap,
2295                                 $conds,
2296                                 $fname,
2297                                 $insertOptions,
2298                                 $selectOptions
2299                         );
2300                 }
2301
2302                 // For web requests, do a locking SELECT and then INSERT. This puts the SELECT burden
2303                 // on only the master (without needing row-based-replication). It also makes it easy to
2304                 // know how big the INSERT is going to be.
2305                 $fields = [];
2306                 foreach ( $varMap as $dstColumn => $sourceColumnOrSql ) {
2307                         $fields[] = $this->fieldNameWithAlias( $sourceColumnOrSql, $dstColumn );
2308                 }
2309                 $selectOptions[] = 'FOR UPDATE';
2310                 $res = $this->select( $srcTable, implode( ',', $fields ), $conds, $fname, $selectOptions );
2311                 if ( !$res ) {
2312                         return false;
2313                 }
2314
2315                 $rows = [];
2316                 foreach ( $res as $row ) {
2317                         $rows[] = (array)$row;
2318                 }
2319
2320                 return $this->insert( $destTable, $rows, $fname, $insertOptions );
2321         }
2322
2323         protected function nativeInsertSelect( $destTable, $srcTable, $varMap, $conds,
2324                 $fname = __METHOD__,
2325                 $insertOptions = [], $selectOptions = []
2326         ) {
2327                 $destTable = $this->tableName( $destTable );
2328
2329                 if ( !is_array( $insertOptions ) ) {
2330                         $insertOptions = [ $insertOptions ];
2331                 }
2332
2333                 $insertOptions = $this->makeInsertOptions( $insertOptions );
2334
2335                 if ( !is_array( $selectOptions ) ) {
2336                         $selectOptions = [ $selectOptions ];
2337                 }
2338
2339                 list( $startOpts, $useIndex, $tailOpts, $ignoreIndex ) = $this->makeSelectOptions(
2340                         $selectOptions );
2341
2342                 if ( is_array( $srcTable ) ) {
2343                         $srcTable = implode( ',', array_map( [ $this, 'tableName' ], $srcTable ) );
2344                 } else {
2345                         $srcTable = $this->tableName( $srcTable );
2346                 }
2347
2348                 $sql = "INSERT $insertOptions" .
2349                         " INTO $destTable (" . implode( ',', array_keys( $varMap ) ) . ')' .
2350                         " SELECT $startOpts " . implode( ',', $varMap ) .
2351                         " FROM $srcTable $useIndex $ignoreIndex ";
2352
2353                 if ( $conds != '*' ) {
2354                         if ( is_array( $conds ) ) {
2355                                 $conds = $this->makeList( $conds, self::LIST_AND );
2356                         }
2357                         $sql .= " WHERE $conds";
2358                 }
2359
2360                 $sql .= " $tailOpts";
2361
2362                 return $this->query( $sql, $fname );
2363         }
2364
2365         /**
2366          * Construct a LIMIT query with optional offset. This is used for query
2367          * pages. The SQL should be adjusted so that only the first $limit rows
2368          * are returned. If $offset is provided as well, then the first $offset
2369          * rows should be discarded, and the next $limit rows should be returned.
2370          * If the result of the query is not ordered, then the rows to be returned
2371          * are theoretically arbitrary.
2372          *
2373          * $sql is expected to be a SELECT, if that makes a difference.
2374          *
2375          * The version provided by default works in MySQL and SQLite. It will very
2376          * likely need to be overridden for most other DBMSes.
2377          *
2378          * @param string $sql SQL query we will append the limit too
2379          * @param int $limit The SQL limit
2380          * @param int|bool $offset The SQL offset (default false)
2381          * @throws DBUnexpectedError
2382          * @return string
2383          */
2384         public function limitResult( $sql, $limit, $offset = false ) {
2385                 if ( !is_numeric( $limit ) ) {
2386                         throw new DBUnexpectedError( $this,
2387                                 "Invalid non-numeric limit passed to limitResult()\n" );
2388                 }
2389
2390                 return "$sql LIMIT "
2391                 . ( ( is_numeric( $offset ) && $offset != 0 ) ? "{$offset}," : "" )
2392                 . "{$limit} ";
2393         }
2394
2395         public function unionSupportsOrderAndLimit() {
2396                 return true; // True for almost every DB supported
2397         }
2398
2399         public function unionQueries( $sqls, $all ) {
2400                 $glue = $all ? ') UNION ALL (' : ') UNION (';
2401
2402                 return '(' . implode( $glue, $sqls ) . ')';
2403         }
2404
2405         public function conditional( $cond, $trueVal, $falseVal ) {
2406                 if ( is_array( $cond ) ) {
2407                         $cond = $this->makeList( $cond, self::LIST_AND );
2408                 }
2409
2410                 return " (CASE WHEN $cond THEN $trueVal ELSE $falseVal END) ";
2411         }
2412
2413         public function strreplace( $orig, $old, $new ) {
2414                 return "REPLACE({$orig}, {$old}, {$new})";
2415         }
2416
2417         public function getServerUptime() {
2418                 return 0;
2419         }
2420
2421         public function wasDeadlock() {
2422                 return false;
2423         }
2424
2425         public function wasLockTimeout() {
2426                 return false;
2427         }
2428
2429         public function wasErrorReissuable() {
2430                 return false;
2431         }
2432
2433         public function wasReadOnlyError() {
2434                 return false;
2435         }
2436
2437         /**
2438          * Do not use this method outside of Database/DBError classes
2439          *
2440          * @param integer|string $errno
2441          * @return bool Whether the given query error was a connection drop
2442          */
2443         public function wasConnectionError( $errno ) {
2444                 return false;
2445         }
2446
2447         public function deadlockLoop() {
2448                 $args = func_get_args();
2449                 $function = array_shift( $args );
2450                 $tries = self::DEADLOCK_TRIES;
2451
2452                 $this->begin( __METHOD__ );
2453
2454                 $retVal = null;
2455                 /** @var Exception $e */
2456                 $e = null;
2457                 do {
2458                         try {
2459                                 $retVal = call_user_func_array( $function, $args );
2460                                 break;
2461                         } catch ( DBQueryError $e ) {
2462                                 if ( $this->wasDeadlock() ) {
2463                                         // Retry after a randomized delay
2464                                         usleep( mt_rand( self::DEADLOCK_DELAY_MIN, self::DEADLOCK_DELAY_MAX ) );
2465                                 } else {
2466                                         // Throw the error back up
2467                                         throw $e;
2468                                 }
2469                         }
2470                 } while ( --$tries > 0 );
2471
2472                 if ( $tries <= 0 ) {
2473                         // Too many deadlocks; give up
2474                         $this->rollback( __METHOD__ );
2475                         throw $e;
2476                 } else {
2477                         $this->commit( __METHOD__ );
2478
2479                         return $retVal;
2480                 }
2481         }
2482
2483         public function masterPosWait( DBMasterPos $pos, $timeout ) {
2484                 # Real waits are implemented in the subclass.
2485                 return 0;
2486         }
2487
2488         public function getReplicaPos() {
2489                 # Stub
2490                 return false;
2491         }
2492
2493         public function getMasterPos() {
2494                 # Stub
2495                 return false;
2496         }
2497
2498         public function serverIsReadOnly() {
2499                 return false;
2500         }
2501
2502         final public function onTransactionResolution( callable $callback, $fname = __METHOD__ ) {
2503                 if ( !$this->mTrxLevel ) {
2504                         throw new DBUnexpectedError( $this, "No transaction is active." );
2505                 }
2506                 $this->mTrxEndCallbacks[] = [ $callback, $fname ];
2507         }
2508
2509         final public function onTransactionIdle( callable $callback, $fname = __METHOD__ ) {
2510                 $this->mTrxIdleCallbacks[] = [ $callback, $fname ];
2511                 if ( !$this->mTrxLevel ) {
2512                         $this->runOnTransactionIdleCallbacks( self::TRIGGER_IDLE );
2513                 }
2514         }
2515
2516         final public function onTransactionPreCommitOrIdle( callable $callback, $fname = __METHOD__ ) {
2517                 if ( $this->mTrxLevel ) {
2518                         $this->mTrxPreCommitCallbacks[] = [ $callback, $fname ];
2519                 } else {
2520                         // If no transaction is active, then make one for this callback
2521                         $this->startAtomic( __METHOD__ );
2522                         try {
2523                                 call_user_func( $callback );
2524                                 $this->endAtomic( __METHOD__ );
2525                         } catch ( Exception $e ) {
2526                                 $this->rollback( __METHOD__, self::FLUSHING_INTERNAL );
2527                                 throw $e;
2528                         }
2529                 }
2530         }
2531
2532         final public function setTransactionListener( $name, callable $callback = null ) {
2533                 if ( $callback ) {
2534                         $this->mTrxRecurringCallbacks[$name] = $callback;
2535                 } else {
2536                         unset( $this->mTrxRecurringCallbacks[$name] );
2537                 }
2538         }
2539
2540         /**
2541          * Whether to disable running of post-COMMIT/ROLLBACK callbacks
2542          *
2543          * This method should not be used outside of Database/LoadBalancer
2544          *
2545          * @param bool $suppress
2546          * @since 1.28
2547          */
2548         final public function setTrxEndCallbackSuppression( $suppress ) {
2549                 $this->mTrxEndCallbacksSuppressed = $suppress;
2550         }
2551
2552         /**
2553          * Actually run and consume any "on transaction idle/resolution" callbacks.
2554          *
2555          * This method should not be used outside of Database/LoadBalancer
2556          *
2557          * @param integer $trigger IDatabase::TRIGGER_* constant
2558          * @since 1.20
2559          * @throws Exception
2560          */
2561         public function runOnTransactionIdleCallbacks( $trigger ) {
2562                 if ( $this->mTrxEndCallbacksSuppressed ) {
2563                         return;
2564                 }
2565
2566                 $autoTrx = $this->getFlag( self::DBO_TRX ); // automatic begin() enabled?
2567                 /** @var Exception $e */
2568                 $e = null; // first exception
2569                 do { // callbacks may add callbacks :)
2570                         $callbacks = array_merge(
2571                                 $this->mTrxIdleCallbacks,
2572                                 $this->mTrxEndCallbacks // include "transaction resolution" callbacks
2573                         );
2574                         $this->mTrxIdleCallbacks = []; // consumed (and recursion guard)
2575                         $this->mTrxEndCallbacks = []; // consumed (recursion guard)
2576                         foreach ( $callbacks as $callback ) {
2577                                 try {
2578                                         list( $phpCallback ) = $callback;
2579                                         $this->clearFlag( self::DBO_TRX ); // make each query its own transaction
2580                                         call_user_func_array( $phpCallback, [ $trigger ] );
2581                                         if ( $autoTrx ) {
2582                                                 $this->setFlag( self::DBO_TRX ); // restore automatic begin()
2583                                         } else {
2584                                                 $this->clearFlag( self::DBO_TRX ); // restore auto-commit
2585                                         }
2586                                 } catch ( Exception $ex ) {
2587                                         call_user_func( $this->errorLogger, $ex );
2588                                         $e = $e ?: $ex;
2589                                         // Some callbacks may use startAtomic/endAtomic, so make sure
2590                                         // their transactions are ended so other callbacks don't fail
2591                                         if ( $this->trxLevel() ) {
2592                                                 $this->rollback( __METHOD__, self::FLUSHING_INTERNAL );
2593                                         }
2594                                 }
2595                         }
2596                 } while ( count( $this->mTrxIdleCallbacks ) );
2597
2598                 if ( $e instanceof Exception ) {
2599                         throw $e; // re-throw any first exception
2600                 }
2601         }
2602
2603         /**
2604          * Actually run and consume any "on transaction pre-commit" callbacks.
2605          *
2606          * This method should not be used outside of Database/LoadBalancer
2607          *
2608          * @since 1.22
2609          * @throws Exception
2610          */
2611         public function runOnTransactionPreCommitCallbacks() {
2612                 $e = null; // first exception
2613                 do { // callbacks may add callbacks :)
2614                         $callbacks = $this->mTrxPreCommitCallbacks;
2615                         $this->mTrxPreCommitCallbacks = []; // consumed (and recursion guard)
2616                         foreach ( $callbacks as $callback ) {
2617                                 try {
2618                                         list( $phpCallback ) = $callback;
2619                                         call_user_func( $phpCallback );
2620                                 } catch ( Exception $ex ) {
2621                                         call_user_func( $this->errorLogger, $ex );
2622                                         $e = $e ?: $ex;
2623                                 }
2624                         }
2625                 } while ( count( $this->mTrxPreCommitCallbacks ) );
2626
2627                 if ( $e instanceof Exception ) {
2628                         throw $e; // re-throw any first exception
2629                 }
2630         }
2631
2632         /**
2633          * Actually run any "transaction listener" callbacks.
2634          *
2635          * This method should not be used outside of Database/LoadBalancer
2636          *
2637          * @param integer $trigger IDatabase::TRIGGER_* constant
2638          * @throws Exception
2639          * @since 1.20
2640          */
2641         public function runTransactionListenerCallbacks( $trigger ) {
2642                 if ( $this->mTrxEndCallbacksSuppressed ) {
2643                         return;
2644                 }
2645
2646                 /** @var Exception $e */
2647                 $e = null; // first exception
2648
2649                 foreach ( $this->mTrxRecurringCallbacks as $phpCallback ) {
2650                         try {
2651                                 $phpCallback( $trigger, $this );
2652                         } catch ( Exception $ex ) {
2653                                 call_user_func( $this->errorLogger, $ex );
2654                                 $e = $e ?: $ex;
2655                         }
2656                 }
2657
2658                 if ( $e instanceof Exception ) {
2659                         throw $e; // re-throw any first exception
2660                 }
2661         }
2662
2663         final public function startAtomic( $fname = __METHOD__ ) {
2664                 if ( !$this->mTrxLevel ) {
2665                         $this->begin( $fname, self::TRANSACTION_INTERNAL );
2666                         // If DBO_TRX is set, a series of startAtomic/endAtomic pairs will result
2667                         // in all changes being in one transaction to keep requests transactional.
2668                         if ( !$this->getFlag( self::DBO_TRX ) ) {
2669                                 $this->mTrxAutomaticAtomic = true;
2670                         }
2671                 }
2672
2673                 $this->mTrxAtomicLevels[] = $fname;
2674         }
2675
2676         final public function endAtomic( $fname = __METHOD__ ) {
2677                 if ( !$this->mTrxLevel ) {
2678                         throw new DBUnexpectedError( $this, "No atomic transaction is open (got $fname)." );
2679                 }
2680                 if ( !$this->mTrxAtomicLevels ||
2681                         array_pop( $this->mTrxAtomicLevels ) !== $fname
2682                 ) {
2683                         throw new DBUnexpectedError( $this, "Invalid atomic section ended (got $fname)." );
2684                 }
2685
2686                 if ( !$this->mTrxAtomicLevels && $this->mTrxAutomaticAtomic ) {
2687                         $this->commit( $fname, self::FLUSHING_INTERNAL );
2688                 }
2689         }
2690
2691         final public function doAtomicSection( $fname, callable $callback ) {
2692                 $this->startAtomic( $fname );
2693                 try {
2694                         $res = call_user_func_array( $callback, [ $this, $fname ] );
2695                 } catch ( Exception $e ) {
2696                         $this->rollback( $fname, self::FLUSHING_INTERNAL );
2697                         throw $e;
2698                 }
2699                 $this->endAtomic( $fname );
2700
2701                 return $res;
2702         }
2703
2704         final public function begin( $fname = __METHOD__, $mode = self::TRANSACTION_EXPLICIT ) {
2705                 // Protect against mismatched atomic section, transaction nesting, and snapshot loss
2706                 if ( $this->mTrxLevel ) {
2707                         if ( $this->mTrxAtomicLevels ) {
2708                                 $levels = implode( ', ', $this->mTrxAtomicLevels );
2709                                 $msg = "$fname: Got explicit BEGIN while atomic section(s) $levels are open.";
2710                                 throw new DBUnexpectedError( $this, $msg );
2711                         } elseif ( !$this->mTrxAutomatic ) {
2712                                 $msg = "$fname: Explicit transaction already active (from {$this->mTrxFname}).";
2713                                 throw new DBUnexpectedError( $this, $msg );
2714                         } else {
2715                                 // @TODO: make this an exception at some point
2716                                 $msg = "$fname: Implicit transaction already active (from {$this->mTrxFname}).";
2717                                 $this->queryLogger->error( $msg );
2718                                 return; // join the main transaction set
2719                         }
2720                 } elseif ( $this->getFlag( self::DBO_TRX ) && $mode !== self::TRANSACTION_INTERNAL ) {
2721                         // @TODO: make this an exception at some point
2722                         $msg = "$fname: Implicit transaction expected (DBO_TRX set).";
2723                         $this->queryLogger->error( $msg );
2724                         return; // let any writes be in the main transaction
2725                 }
2726
2727                 // Avoid fatals if close() was called
2728                 $this->assertOpen();
2729
2730                 $this->doBegin( $fname );
2731                 $this->mTrxTimestamp = microtime( true );
2732                 $this->mTrxFname = $fname;
2733                 $this->mTrxDoneWrites = false;
2734                 $this->mTrxAutomaticAtomic = false;
2735                 $this->mTrxAtomicLevels = [];
2736                 $this->mTrxShortId = sprintf( '%06x', mt_rand( 0, 0xffffff ) );
2737                 $this->mTrxWriteDuration = 0.0;
2738                 $this->mTrxWriteQueryCount = 0;
2739                 $this->mTrxWriteAdjDuration = 0.0;
2740                 $this->mTrxWriteAdjQueryCount = 0;
2741                 $this->mTrxWriteCallers = [];
2742                 // First SELECT after BEGIN will establish the snapshot in REPEATABLE-READ.
2743                 // Get an estimate of the replica DB lag before then, treating estimate staleness
2744                 // as lag itself just to be safe
2745                 $status = $this->getApproximateLagStatus();
2746                 $this->mTrxReplicaLag = $status['lag'] + ( microtime( true ) - $status['since'] );
2747                 // T147697: make explicitTrxActive() return true until begin() finishes. This way, no
2748                 // caller will think its OK to muck around with the transaction just because startAtomic()
2749                 // has not yet completed (e.g. setting mTrxAtomicLevels).
2750                 $this->mTrxAutomatic = ( $mode === self::TRANSACTION_INTERNAL );
2751         }
2752
2753         /**
2754          * Issues the BEGIN command to the database server.
2755          *
2756          * @see Database::begin()
2757          * @param string $fname
2758          */
2759         protected function doBegin( $fname ) {
2760                 $this->query( 'BEGIN', $fname );
2761                 $this->mTrxLevel = 1;
2762         }
2763
2764         final public function commit( $fname = __METHOD__, $flush = '' ) {
2765                 if ( $this->mTrxLevel && $this->mTrxAtomicLevels ) {
2766                         // There are still atomic sections open. This cannot be ignored
2767                         $levels = implode( ', ', $this->mTrxAtomicLevels );
2768                         throw new DBUnexpectedError(
2769                                 $this,
2770                                 "$fname: Got COMMIT while atomic sections $levels are still open."
2771                         );
2772                 }
2773
2774                 if ( $flush === self::FLUSHING_INTERNAL || $flush === self::FLUSHING_ALL_PEERS ) {
2775                         if ( !$this->mTrxLevel ) {
2776                                 return; // nothing to do
2777                         } elseif ( !$this->mTrxAutomatic ) {
2778                                 throw new DBUnexpectedError(
2779                                         $this,
2780                                         "$fname: Flushing an explicit transaction, getting out of sync."
2781                                 );
2782                         }
2783                 } else {
2784                         if ( !$this->mTrxLevel ) {
2785                                 $this->queryLogger->error(
2786                                         "$fname: No transaction to commit, something got out of sync." );
2787                                 return; // nothing to do
2788                         } elseif ( $this->mTrxAutomatic ) {
2789                                 // @TODO: make this an exception at some point
2790                                 $msg = "$fname: Explicit commit of implicit transaction.";
2791                                 $this->queryLogger->error( $msg );
2792                                 return; // wait for the main transaction set commit round
2793                         }
2794                 }
2795
2796                 // Avoid fatals if close() was called
2797                 $this->assertOpen();
2798
2799                 $this->runOnTransactionPreCommitCallbacks();
2800                 $writeTime = $this->pendingWriteQueryDuration( self::ESTIMATE_DB_APPLY );
2801                 $this->doCommit( $fname );
2802                 if ( $this->mTrxDoneWrites ) {
2803                         $this->mLastWriteTime = microtime( true );
2804                         $this->trxProfiler->transactionWritingOut(
2805                                 $this->mServer, $this->mDBname, $this->mTrxShortId, $writeTime );
2806                 }
2807
2808                 $this->runOnTransactionIdleCallbacks( self::TRIGGER_COMMIT );
2809                 $this->runTransactionListenerCallbacks( self::TRIGGER_COMMIT );
2810         }
2811
2812         /**
2813          * Issues the COMMIT command to the database server.
2814          *
2815          * @see Database::commit()
2816          * @param string $fname
2817          */
2818         protected function doCommit( $fname ) {
2819                 if ( $this->mTrxLevel ) {
2820                         $this->query( 'COMMIT', $fname );
2821                         $this->mTrxLevel = 0;
2822                 }
2823         }
2824
2825         final public function rollback( $fname = __METHOD__, $flush = '' ) {
2826                 if ( $flush === self::FLUSHING_INTERNAL || $flush === self::FLUSHING_ALL_PEERS ) {
2827                         if ( !$this->mTrxLevel ) {
2828                                 return; // nothing to do
2829                         }
2830                 } else {
2831                         if ( !$this->mTrxLevel ) {
2832                                 $this->queryLogger->error(
2833                                         "$fname: No transaction to rollback, something got out of sync." );
2834                                 return; // nothing to do
2835                         } elseif ( $this->getFlag( self::DBO_TRX ) ) {
2836                                 throw new DBUnexpectedError(
2837                                         $this,
2838                                         "$fname: Expected mass rollback of all peer databases (DBO_TRX set)."
2839                                 );
2840                         }
2841                 }
2842
2843                 // Avoid fatals if close() was called
2844                 $this->assertOpen();
2845
2846                 $this->doRollback( $fname );
2847                 $this->mTrxAtomicLevels = [];
2848                 if ( $this->mTrxDoneWrites ) {
2849                         $this->trxProfiler->transactionWritingOut(
2850                                 $this->mServer, $this->mDBname, $this->mTrxShortId );
2851                 }
2852
2853                 $this->mTrxIdleCallbacks = []; // clear
2854                 $this->mTrxPreCommitCallbacks = []; // clear
2855                 $this->runOnTransactionIdleCallbacks( self::TRIGGER_ROLLBACK );
2856                 $this->runTransactionListenerCallbacks( self::TRIGGER_ROLLBACK );
2857         }
2858
2859         /**
2860          * Issues the ROLLBACK command to the database server.
2861          *
2862          * @see Database::rollback()
2863          * @param string $fname
2864          */
2865         protected function doRollback( $fname ) {
2866                 if ( $this->mTrxLevel ) {
2867                         # Disconnects cause rollback anyway, so ignore those errors
2868                         $ignoreErrors = true;
2869                         $this->query( 'ROLLBACK', $fname, $ignoreErrors );
2870                         $this->mTrxLevel = 0;
2871                 }
2872         }
2873
2874         public function flushSnapshot( $fname = __METHOD__ ) {
2875                 if ( $this->writesOrCallbacksPending() || $this->explicitTrxActive() ) {
2876                         // This only flushes transactions to clear snapshots, not to write data
2877                         $fnames = implode( ', ', $this->pendingWriteAndCallbackCallers() );
2878                         throw new DBUnexpectedError(
2879                                 $this,
2880                                 "$fname: Cannot flush snapshot because writes are pending ($fnames)."
2881                         );
2882                 }
2883
2884                 $this->commit( $fname, self::FLUSHING_INTERNAL );
2885         }
2886
2887         public function explicitTrxActive() {
2888                 return $this->mTrxLevel && ( $this->mTrxAtomicLevels || !$this->mTrxAutomatic );
2889         }
2890
2891         public function duplicateTableStructure(
2892                 $oldName, $newName, $temporary = false, $fname = __METHOD__
2893         ) {
2894                 throw new RuntimeException( __METHOD__ . ' is not implemented in descendant class' );
2895         }
2896
2897         public function listTables( $prefix = null, $fname = __METHOD__ ) {
2898                 throw new RuntimeException( __METHOD__ . ' is not implemented in descendant class' );
2899         }
2900
2901         public function listViews( $prefix = null, $fname = __METHOD__ ) {
2902                 throw new RuntimeException( __METHOD__ . ' is not implemented in descendant class' );
2903         }
2904
2905         public function timestamp( $ts = 0 ) {
2906                 $t = new ConvertibleTimestamp( $ts );
2907                 // Let errors bubble up to avoid putting garbage in the DB
2908                 return $t->getTimestamp( TS_MW );
2909         }
2910
2911         public function timestampOrNull( $ts = null ) {
2912                 if ( is_null( $ts ) ) {
2913                         return null;
2914                 } else {
2915                         return $this->timestamp( $ts );
2916                 }
2917         }
2918
2919         /**
2920          * Take the result from a query, and wrap it in a ResultWrapper if
2921          * necessary. Boolean values are passed through as is, to indicate success
2922          * of write queries or failure.
2923          *
2924          * Once upon a time, Database::query() returned a bare MySQL result
2925          * resource, and it was necessary to call this function to convert it to
2926          * a wrapper. Nowadays, raw database objects are never exposed to external
2927          * callers, so this is unnecessary in external code.
2928          *
2929          * @param bool|ResultWrapper|resource|object $result
2930          * @return bool|ResultWrapper
2931          */
2932         protected function resultObject( $result ) {
2933                 if ( !$result ) {
2934                         return false;
2935                 } elseif ( $result instanceof ResultWrapper ) {
2936                         return $result;
2937                 } elseif ( $result === true ) {
2938                         // Successful write query
2939                         return $result;
2940                 } else {
2941                         return new ResultWrapper( $this, $result );
2942                 }
2943         }
2944
2945         public function ping( &$rtt = null ) {
2946                 // Avoid hitting the server if it was hit recently
2947                 if ( $this->isOpen() && ( microtime( true ) - $this->lastPing ) < self::PING_TTL ) {
2948                         if ( !func_num_args() || $this->mRTTEstimate > 0 ) {
2949                                 $rtt = $this->mRTTEstimate;
2950                                 return true; // don't care about $rtt
2951                         }
2952                 }
2953
2954                 // This will reconnect if possible or return false if not
2955                 $this->clearFlag( self::DBO_TRX, self::REMEMBER_PRIOR );
2956                 $ok = ( $this->query( self::PING_QUERY, __METHOD__, true ) !== false );
2957                 $this->restoreFlags( self::RESTORE_PRIOR );
2958
2959                 if ( $ok ) {
2960                         $rtt = $this->mRTTEstimate;
2961                 }
2962
2963                 return $ok;
2964         }
2965
2966         /**
2967          * @return bool
2968          */
2969         protected function reconnect() {
2970                 $this->closeConnection();
2971                 $this->mOpened = false;
2972                 $this->mConn = false;
2973                 try {
2974                         $this->open( $this->mServer, $this->mUser, $this->mPassword, $this->mDBname );
2975                         $this->lastPing = microtime( true );
2976                         $ok = true;
2977                 } catch ( DBConnectionError $e ) {
2978                         $ok = false;
2979                 }
2980
2981                 return $ok;
2982         }
2983
2984         public function getSessionLagStatus() {
2985                 return $this->getTransactionLagStatus() ?: $this->getApproximateLagStatus();
2986         }
2987
2988         /**
2989          * Get the replica DB lag when the current transaction started
2990          *
2991          * This is useful when transactions might use snapshot isolation
2992          * (e.g. REPEATABLE-READ in innodb), so the "real" lag of that data
2993          * is this lag plus transaction duration. If they don't, it is still
2994          * safe to be pessimistic. This returns null if there is no transaction.
2995          *
2996          * @return array|null ('lag': seconds or false on error, 'since': UNIX timestamp of BEGIN)
2997          * @since 1.27
2998          */
2999         protected function getTransactionLagStatus() {
3000                 return $this->mTrxLevel
3001                         ? [ 'lag' => $this->mTrxReplicaLag, 'since' => $this->trxTimestamp() ]
3002                         : null;
3003         }
3004
3005         /**
3006          * Get a replica DB lag estimate for this server
3007          *
3008          * @return array ('lag': seconds or false on error, 'since': UNIX timestamp of estimate)
3009          * @since 1.27
3010          */
3011         protected function getApproximateLagStatus() {
3012                 return [
3013                         'lag'   => $this->getLBInfo( 'replica' ) ? $this->getLag() : 0,
3014                         'since' => microtime( true )
3015                 ];
3016         }
3017
3018         /**
3019          * Merge the result of getSessionLagStatus() for several DBs
3020          * using the most pessimistic values to estimate the lag of
3021          * any data derived from them in combination
3022          *
3023          * This is information is useful for caching modules
3024          *
3025          * @see WANObjectCache::set()
3026          * @see WANObjectCache::getWithSetCallback()
3027          *
3028          * @param IDatabase $db1
3029          * @param IDatabase ...
3030          * @return array Map of values:
3031          *   - lag: highest lag of any of the DBs or false on error (e.g. replication stopped)
3032          *   - since: oldest UNIX timestamp of any of the DB lag estimates
3033          *   - pending: whether any of the DBs have uncommitted changes
3034          * @since 1.27
3035          */
3036         public static function getCacheSetOptions( IDatabase $db1 ) {
3037                 $res = [ 'lag' => 0, 'since' => INF, 'pending' => false ];
3038                 foreach ( func_get_args() as $db ) {
3039                         /** @var IDatabase $db */
3040                         $status = $db->getSessionLagStatus();
3041                         if ( $status['lag'] === false ) {
3042                                 $res['lag'] = false;
3043                         } elseif ( $res['lag'] !== false ) {
3044                                 $res['lag'] = max( $res['lag'], $status['lag'] );
3045                         }
3046                         $res['since'] = min( $res['since'], $status['since'] );
3047                         $res['pending'] = $res['pending'] ?: $db->writesPending();
3048                 }
3049
3050                 return $res;
3051         }
3052
3053         public function getLag() {
3054                 return 0;
3055         }
3056
3057         public function maxListLen() {
3058                 return 0;
3059         }
3060
3061         public function encodeBlob( $b ) {
3062                 return $b;
3063         }
3064
3065         public function decodeBlob( $b ) {
3066                 if ( $b instanceof Blob ) {
3067                         $b = $b->fetch();
3068                 }
3069                 return $b;
3070         }
3071
3072         public function setSessionOptions( array $options ) {
3073         }
3074
3075         public function sourceFile(
3076                 $filename,
3077                 callable $lineCallback = null,
3078                 callable $resultCallback = null,
3079                 $fname = false,
3080                 callable $inputCallback = null
3081         ) {
3082                 MediaWiki\suppressWarnings();
3083                 $fp = fopen( $filename, 'r' );
3084                 MediaWiki\restoreWarnings();
3085
3086                 if ( false === $fp ) {
3087                         throw new RuntimeException( "Could not open \"{$filename}\".\n" );
3088                 }
3089
3090                 if ( !$fname ) {
3091                         $fname = __METHOD__ . "( $filename )";
3092                 }
3093
3094                 try {
3095                         $error = $this->sourceStream(
3096                                 $fp, $lineCallback, $resultCallback, $fname, $inputCallback );
3097                 } catch ( Exception $e ) {
3098                         fclose( $fp );
3099                         throw $e;
3100                 }
3101
3102                 fclose( $fp );
3103
3104                 return $error;
3105         }
3106
3107         public function setSchemaVars( $vars ) {
3108                 $this->mSchemaVars = $vars;
3109         }
3110
3111         public function sourceStream(
3112                 $fp,
3113                 callable $lineCallback = null,
3114                 callable $resultCallback = null,
3115                 $fname = __METHOD__,
3116                 callable $inputCallback = null
3117         ) {
3118                 $cmd = '';
3119
3120                 while ( !feof( $fp ) ) {
3121                         if ( $lineCallback ) {
3122                                 call_user_func( $lineCallback );
3123                         }
3124
3125                         $line = trim( fgets( $fp ) );
3126
3127                         if ( $line == '' ) {
3128                                 continue;
3129                         }
3130
3131                         if ( '-' == $line[0] && '-' == $line[1] ) {
3132                                 continue;
3133                         }
3134
3135                         if ( $cmd != '' ) {
3136                                 $cmd .= ' ';
3137                         }
3138
3139                         $done = $this->streamStatementEnd( $cmd, $line );
3140
3141                         $cmd .= "$line\n";
3142
3143                         if ( $done || feof( $fp ) ) {
3144                                 $cmd = $this->replaceVars( $cmd );
3145
3146                                 if ( !$inputCallback || call_user_func( $inputCallback, $cmd ) ) {
3147                                         $res = $this->query( $cmd, $fname );
3148
3149                                         if ( $resultCallback ) {
3150                                                 call_user_func( $resultCallback, $res, $this );
3151                                         }
3152
3153                                         if ( false === $res ) {
3154                                                 $err = $this->lastError();
3155
3156                                                 return "Query \"{$cmd}\" failed with error code \"$err\".\n";
3157                                         }
3158                                 }
3159                                 $cmd = '';
3160                         }
3161                 }
3162
3163                 return true;
3164         }
3165
3166         /**
3167          * Called by sourceStream() to check if we've reached a statement end
3168          *
3169          * @param string &$sql SQL assembled so far
3170          * @param string &$newLine New line about to be added to $sql
3171          * @return bool Whether $newLine contains end of the statement
3172          */
3173         public function streamStatementEnd( &$sql, &$newLine ) {
3174                 if ( $this->delimiter ) {
3175                         $prev = $newLine;
3176                         $newLine = preg_replace(
3177                                 '/' . preg_quote( $this->delimiter, '/' ) . '$/', '', $newLine );
3178                         if ( $newLine != $prev ) {
3179                                 return true;
3180                         }
3181                 }
3182
3183                 return false;
3184         }
3185
3186         /**
3187          * Database independent variable replacement. Replaces a set of variables
3188          * in an SQL statement with their contents as given by $this->getSchemaVars().
3189          *
3190          * Supports '{$var}' `{$var}` and / *$var* / (without the spaces) style variables.
3191          *
3192          * - '{$var}' should be used for text and is passed through the database's
3193          *   addQuotes method.
3194          * - `{$var}` should be used for identifiers (e.g. table and database names).
3195          *   It is passed through the database's addIdentifierQuotes method which
3196          *   can be overridden if the database uses something other than backticks.
3197          * - / *_* / or / *$wgDBprefix* / passes the name that follows through the
3198          *   database's tableName method.
3199          * - / *i* / passes the name that follows through the database's indexName method.
3200          * - In all other cases, / *$var* / is left unencoded. Except for table options,
3201          *   its use should be avoided. In 1.24 and older, string encoding was applied.
3202          *
3203          * @param string $ins SQL statement to replace variables in
3204          * @return string The new SQL statement with variables replaced
3205          */
3206         protected function replaceVars( $ins ) {
3207                 $vars = $this->getSchemaVars();
3208                 return preg_replace_callback(
3209                         '!
3210                                 /\* (\$wgDBprefix|[_i]) \*/ (\w*) | # 1-2. tableName, indexName
3211                                 \'\{\$ (\w+) }\'                  | # 3. addQuotes
3212                                 `\{\$ (\w+) }`                    | # 4. addIdentifierQuotes
3213                                 /\*\$ (\w+) \*/                     # 5. leave unencoded
3214                         !x',
3215                         function ( $m ) use ( $vars ) {
3216                                 // Note: Because of <https://bugs.php.net/bug.php?id=51881>,
3217                                 // check for both nonexistent keys *and* the empty string.
3218                                 if ( isset( $m[1] ) && $m[1] !== '' ) {
3219                                         if ( $m[1] === 'i' ) {
3220                                                 return $this->indexName( $m[2] );
3221                                         } else {
3222                                                 return $this->tableName( $m[2] );
3223                                         }
3224                                 } elseif ( isset( $m[3] ) && $m[3] !== '' && array_key_exists( $m[3], $vars ) ) {
3225                                         return $this->addQuotes( $vars[$m[3]] );
3226                                 } elseif ( isset( $m[4] ) && $m[4] !== '' && array_key_exists( $m[4], $vars ) ) {
3227                                         return $this->addIdentifierQuotes( $vars[$m[4]] );
3228                                 } elseif ( isset( $m[5] ) && $m[5] !== '' && array_key_exists( $m[5], $vars ) ) {
3229                                         return $vars[$m[5]];
3230                                 } else {
3231                                         return $m[0];
3232                                 }
3233                         },
3234                         $ins
3235                 );
3236         }
3237
3238         /**
3239          * Get schema variables. If none have been set via setSchemaVars(), then
3240          * use some defaults from the current object.
3241          *
3242          * @return array
3243          */
3244         protected function getSchemaVars() {
3245                 if ( $this->mSchemaVars ) {
3246                         return $this->mSchemaVars;
3247                 } else {
3248                         return $this->getDefaultSchemaVars();
3249                 }
3250         }
3251
3252         /**
3253          * Get schema variables to use if none have been set via setSchemaVars().
3254          *
3255          * Override this in derived classes to provide variables for tables.sql
3256          * and SQL patch files.
3257          *
3258          * @return array
3259          */
3260         protected function getDefaultSchemaVars() {
3261                 return [];
3262         }
3263
3264         public function lockIsFree( $lockName, $method ) {
3265                 return true;
3266         }
3267
3268         public function lock( $lockName, $method, $timeout = 5 ) {
3269                 $this->mNamedLocksHeld[$lockName] = 1;
3270
3271                 return true;
3272         }
3273
3274         public function unlock( $lockName, $method ) {
3275                 unset( $this->mNamedLocksHeld[$lockName] );
3276
3277                 return true;
3278         }
3279
3280         public function getScopedLockAndFlush( $lockKey, $fname, $timeout ) {
3281                 if ( $this->writesOrCallbacksPending() ) {
3282                         // This only flushes transactions to clear snapshots, not to write data
3283                         $fnames = implode( ', ', $this->pendingWriteAndCallbackCallers() );
3284                         throw new DBUnexpectedError(
3285                                 $this,
3286                                 "$fname: Cannot flush pre-lock snapshot because writes are pending ($fnames)."
3287                         );
3288                 }
3289
3290                 if ( !$this->lock( $lockKey, $fname, $timeout ) ) {
3291                         return null;
3292                 }
3293
3294                 $unlocker = new ScopedCallback( function () use ( $lockKey, $fname ) {
3295                         if ( $this->trxLevel() ) {
3296                                 // There is a good chance an exception was thrown, causing any early return
3297                                 // from the caller. Let any error handler get a chance to issue rollback().
3298                                 // If there isn't one, let the error bubble up and trigger server-side rollback.
3299                                 $this->onTransactionResolution(
3300                                         function () use ( $lockKey, $fname ) {
3301                                                 $this->unlock( $lockKey, $fname );
3302                                         },
3303                                         $fname
3304                                 );
3305                         } else {
3306                                 $this->unlock( $lockKey, $fname );
3307                         }
3308                 } );
3309
3310                 $this->commit( $fname, self::FLUSHING_INTERNAL );
3311
3312                 return $unlocker;
3313         }
3314
3315         public function namedLocksEnqueue() {
3316                 return false;
3317         }
3318
3319         public function tableLocksHaveTransactionScope() {
3320                 return true;
3321         }
3322
3323         final public function lockTables( array $read, array $write, $method ) {
3324                 if ( $this->writesOrCallbacksPending() ) {
3325                         throw new DBUnexpectedError( $this, "Transaction writes or callbacks still pending." );
3326                 }
3327
3328                 if ( $this->tableLocksHaveTransactionScope() ) {
3329                         $this->startAtomic( $method );
3330                 }
3331
3332                 return $this->doLockTables( $read, $write, $method );
3333         }
3334
3335         protected function doLockTables( array $read, array $write, $method ) {
3336                 return true;
3337         }
3338
3339         final public function unlockTables( $method ) {
3340                 if ( $this->tableLocksHaveTransactionScope() ) {
3341                         $this->endAtomic( $method );
3342
3343                         return true; // locks released on COMMIT/ROLLBACK
3344                 }
3345
3346                 return $this->doUnlockTables( $method );
3347         }
3348
3349         protected function doUnlockTables( $method ) {
3350                 return true;
3351         }
3352
3353         /**
3354          * Delete a table
3355          * @param string $tableName
3356          * @param string $fName
3357          * @return bool|ResultWrapper
3358          * @since 1.18
3359          */
3360         public function dropTable( $tableName, $fName = __METHOD__ ) {
3361                 if ( !$this->tableExists( $tableName, $fName ) ) {
3362                         return false;
3363                 }
3364                 $sql = "DROP TABLE " . $this->tableName( $tableName ) . " CASCADE";
3365
3366                 return $this->query( $sql, $fName );
3367         }
3368
3369         public function getInfinity() {
3370                 return 'infinity';
3371         }
3372
3373         public function encodeExpiry( $expiry ) {
3374                 return ( $expiry == '' || $expiry == 'infinity' || $expiry == $this->getInfinity() )
3375                         ? $this->getInfinity()
3376                         : $this->timestamp( $expiry );
3377         }
3378
3379         public function decodeExpiry( $expiry, $format = TS_MW ) {
3380                 if ( $expiry == '' || $expiry == 'infinity' || $expiry == $this->getInfinity() ) {
3381                         return 'infinity';
3382                 }
3383
3384                 return ConvertibleTimestamp::convert( $format, $expiry );
3385         }
3386
3387         public function setBigSelects( $value = true ) {
3388                 // no-op
3389         }
3390
3391         public function isReadOnly() {
3392                 return ( $this->getReadOnlyReason() !== false );
3393         }
3394
3395         /**
3396          * @return string|bool Reason this DB is read-only or false if it is not
3397          */
3398         protected function getReadOnlyReason() {
3399                 $reason = $this->getLBInfo( 'readOnlyReason' );
3400
3401                 return is_string( $reason ) ? $reason : false;
3402         }
3403
3404         public function setTableAliases( array $aliases ) {
3405                 $this->tableAliases = $aliases;
3406         }
3407
3408         /**
3409          * @return bool Whether a DB user is required to access the DB
3410          * @since 1.28
3411          */
3412         protected function requiresDatabaseUser() {
3413                 return true;
3414         }
3415
3416         /**
3417          * Get the underlying binding handle, mConn
3418          *
3419          * Makes sure that mConn is set (disconnects and ping() failure can unset it).
3420          * This catches broken callers than catch and ignore disconnection exceptions.
3421          * Unlike checking isOpen(), this is safe to call inside of open().
3422          *
3423          * @return resource|object
3424          * @throws DBUnexpectedError
3425          * @since 1.26
3426          */
3427         protected function getBindingHandle() {
3428                 if ( !$this->mConn ) {
3429                         throw new DBUnexpectedError(
3430                                 $this,
3431                                 'DB connection was already closed or the connection dropped.'
3432                         );
3433                 }
3434
3435                 return $this->mConn;
3436         }
3437
3438         /**
3439          * @since 1.19
3440          * @return string
3441          */
3442         public function __toString() {
3443                 return (string)$this->mConn;
3444         }
3445
3446         /**
3447          * Make sure that copies do not share the same client binding handle
3448          * @throws DBConnectionError
3449          */
3450         public function __clone() {
3451                 $this->connLogger->warning(
3452                         "Cloning " . static::class . " is not recomended; forking connection:\n" .
3453                         ( new RuntimeException() )->getTraceAsString()
3454                 );
3455
3456                 if ( $this->isOpen() ) {
3457                         // Open a new connection resource without messing with the old one
3458                         $this->mOpened = false;
3459                         $this->mConn = false;
3460                         $this->mTrxEndCallbacks = []; // don't copy
3461                         $this->handleSessionLoss(); // no trx or locks anymore
3462                         $this->open( $this->mServer, $this->mUser, $this->mPassword, $this->mDBname );
3463                         $this->lastPing = microtime( true );
3464                 }
3465         }
3466
3467         /**
3468          * Called by serialize. Throw an exception when DB connection is serialized.
3469          * This causes problems on some database engines because the connection is
3470          * not restored on unserialize.
3471          */
3472         public function __sleep() {
3473                 throw new RuntimeException( 'Database serialization may cause problems, since ' .
3474                         'the connection is not restored on wakeup.' );
3475         }
3476
3477         /**
3478          * Run a few simple sanity checks and close dangling connections
3479          */
3480         public function __destruct() {
3481                 if ( $this->mTrxLevel && $this->mTrxDoneWrites ) {
3482                         trigger_error( "Uncommitted DB writes (transaction from {$this->mTrxFname})." );
3483                 }
3484
3485                 $danglingWriters = $this->pendingWriteAndCallbackCallers();
3486                 if ( $danglingWriters ) {
3487                         $fnames = implode( ', ', $danglingWriters );
3488                         trigger_error( "DB transaction writes or callbacks still pending ($fnames)." );
3489                 }
3490
3491                 if ( $this->mConn ) {
3492                         // Avoid connection leaks for sanity. Normally, resources close at script completion.
3493                         // The connection might already be closed in zend/hhvm by now, so suppress warnings.
3494                         \MediaWiki\suppressWarnings();
3495                         $this->closeConnection();
3496                         \MediaWiki\restoreWarnings();
3497                         $this->mConn = false;
3498                         $this->mOpened = false;
3499                 }
3500         }
3501 }
3502
3503 class_alias( Database::class, 'DatabaseBase' ); // b/c for old name
3504 class_alias( Database::class, 'Database' ); // b/c global alias