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 TEMPORARY table operation
 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                         '/^TRUNCATE\s+(?:TEMPORARY\s+)?TABLE\s+(?:IF\s+EXISTS\s+)?[`"\']?(\w+)[`"\']?/i',
 842                         $sql,
 843                         $matches
 844                 ) ) {
 845                         return isset( $this->mSessionTempTables[$matches[1]] );
 846                 } elseif ( preg_match(
 847                         '/^(?:INSERT\s+(?:\w+\s+)?INTO|UPDATE|DELETE\s+FROM)\s+[`"\']?(\w+)[`"\']?/i',
 848                         $sql,
 849                         $matches
 850                 ) ) {
 851                         return isset( $this->mSessionTempTables[$matches[1]] );
 852                 }
 853
 854                 return false;
 855         }
 856
 857         public function query( $sql, $fname = __METHOD__, $tempIgnore = false ) {
 858                 $priorWritesPending = $this->writesOrCallbacksPending();
 859                 $this->mLastQuery = $sql;
 860
 861                 $isWrite = $this->isWriteQuery( $sql );
 862                 if ( $isWrite ) {
 863                         $isNonTempWrite = !$this->registerTempTableOperation( $sql );
 864                 } else {
 865                         $isNonTempWrite = false;
 866                 }
 867
 868                 if ( $isWrite ) {
 869                         # In theory, non-persistent writes are allowed in read-only mode, but due to things
 870                         # like https://bugs.mysql.com/bug.php?id=33669 that might not work anyway...
 871                         $reason = $this->getReadOnlyReason();
 872                         if ( $reason !== false ) {
 873                                 throw new DBReadOnlyError( $this, "Database is read-only: $reason" );
 874                         }
 875                         # Set a flag indicating that writes have been done
 876                         $this->mLastWriteTime = microtime( true );
 877                 }
 878
 879                 # Add trace comment to the begin of the sql string, right after the operator.
 880                 # Or, for one-word queries (like "BEGIN" or COMMIT") add it to the end (T44598)
 881                 $commentedSql = preg_replace( '/\s|$/', " /* $fname {$this->agent} */ ", $sql, 1 );
 882
 883                 # Start implicit transactions that wrap the request if DBO_TRX is enabled
 884                 if ( !$this->mTrxLevel && $this->getFlag( self::DBO_TRX )
 885                         && $this->isTransactableQuery( $sql )
 886                 ) {
 887                         $this->begin( __METHOD__ . " ($fname)", self::TRANSACTION_INTERNAL );
 888                         $this->mTrxAutomatic = true;
 889                 }
 890
 891                 # Keep track of whether the transaction has write queries pending
 892                 if ( $this->mTrxLevel && !$this->mTrxDoneWrites && $isWrite ) {
 893                         $this->mTrxDoneWrites = true;
 894                         $this->trxProfiler->transactionWritingIn(
 895                                 $this->mServer, $this->mDBname, $this->mTrxShortId );
 896                 }
 897
 898                 if ( $this->getFlag( self::DBO_DEBUG ) ) {
 899                         $this->queryLogger->debug( "{$this->mDBname} {$commentedSql}" );
 900                 }
 901
 902                 # Avoid fatals if close() was called
 903                 $this->assertOpen();
 904
 905                 # Send the query to the server
 906                 $ret = $this->doProfiledQuery( $sql, $commentedSql, $isNonTempWrite, $fname );
 907
 908                 # Try reconnecting if the connection was lost
 909                 if ( false === $ret && $this->wasErrorReissuable() ) {
 910                         $recoverable = $this->canRecoverFromDisconnect( $sql, $priorWritesPending );
 911                         # Stash the last error values before anything might clear them
 912                         $lastError = $this->lastError();
 913                         $lastErrno = $this->lastErrno();
 914                         # Update state tracking to reflect transaction loss due to disconnection
 915                         $this->handleSessionLoss();
 916                         if ( $this->reconnect() ) {
 917                                 $msg = __METHOD__ . ": lost connection to {$this->getServer()}; reconnected";
 918                                 $this->connLogger->warning( $msg );
 919                                 $this->queryLogger->warning(
 920                                         "$msg:\n" . ( new RuntimeException() )->getTraceAsString() );
 921
 922                                 if ( !$recoverable ) {
 923                                         # Callers may catch the exception and continue to use the DB
 924                                         $this->reportQueryError( $lastError, $lastErrno, $sql, $fname );
 925                                 } else {
 926                                         # Should be safe to silently retry the query
 927                                         $ret = $this->doProfiledQuery( $sql, $commentedSql, $isNonTempWrite, $fname );
 928                                 }
 929                         } else {
 930                                 $msg = __METHOD__ . ": lost connection to {$this->getServer()} permanently";
 931                                 $this->connLogger->error( $msg );
 932                         }
 933                 }
 934
 935                 if ( false === $ret ) {
 936                         # Deadlocks cause the entire transaction to abort, not just the statement.
 937                         # https://dev.mysql.com/doc/refman/5.7/en/innodb-error-handling.html
 938                         # https://www.postgresql.org/docs/9.1/static/explicit-locking.html
 939                         if ( $this->wasDeadlock() ) {
 940                                 if ( $this->explicitTrxActive() || $priorWritesPending ) {
 941                                         $tempIgnore = false; // not recoverable
 942                                 }
 943                                 # Update state tracking to reflect transaction loss
 944                                 $this->handleSessionLoss();
 945                         }
 946
 947                         $this->reportQueryError(
 948                                 $this->lastError(), $this->lastErrno(), $sql, $fname, $tempIgnore );
 949                 }
 950
 951                 $res = $this->resultObject( $ret );
 952
 953                 return $res;
 954         }
 955
 956         private function doProfiledQuery( $sql, $commentedSql, $isWrite, $fname ) {
 957                 $isMaster = !is_null( $this->getLBInfo( 'master' ) );
 958                 # generalizeSQL() will probably cut down the query to reasonable
 959                 # logging size most of the time. The substr is really just a sanity check.
 960                 if ( $isMaster ) {
 961                         $queryProf = 'query-m: ' . substr( self::generalizeSQL( $sql ), 0, 255 );
 962                 } else {
 963                         $queryProf = 'query: ' . substr( self::generalizeSQL( $sql ), 0, 255 );
 964                 }
 965
 966                 # Include query transaction state
 967                 $queryProf .= $this->mTrxShortId ? " [TRX#{$this->mTrxShortId}]" : "";
 968
 969                 $startTime = microtime( true );
 970                 if ( $this->profiler ) {
 971                         call_user_func( [ $this->profiler, 'profileIn' ], $queryProf );
 972                 }
 973                 $ret = $this->doQuery( $commentedSql );
 974                 if ( $this->profiler ) {
 975                         call_user_func( [ $this->profiler, 'profileOut' ], $queryProf );
 976                 }
 977                 $queryRuntime = max( microtime( true ) - $startTime, 0.0 );
 978
 979                 unset( $queryProfSection ); // profile out (if set)
 980
 981                 if ( $ret !== false ) {
 982                         $this->lastPing = $startTime;
 983                         if ( $isWrite && $this->mTrxLevel ) {
 984                                 $this->updateTrxWriteQueryTime( $sql, $queryRuntime );
 985                                 $this->mTrxWriteCallers[] = $fname;
 986                         }
 987                 }
 988
 989                 if ( $sql === self::PING_QUERY ) {
 990                         $this->mRTTEstimate = $queryRuntime;
 991                 }
 992
 993                 $this->trxProfiler->recordQueryCompletion(
 994                         $queryProf, $startTime, $isWrite, $this->affectedRows()
 995                 );
 996                 $this->queryLogger->debug( $sql, [
 997                         'method' => $fname,
 998                         'master' => $isMaster,
 999                         'runtime' => $queryRuntime,
1000                 ] );
1001
1002                 return $ret;
1003         }
1004
1005         /**
1006          * Update the estimated run-time of a query, not counting large row lock times
1007          *
1008          * LoadBalancer can be set to rollback transactions that will create huge replication
1009          * lag. It bases this estimate off of pendingWriteQueryDuration(). Certain simple
1010          * queries, like inserting a row can take a long time due to row locking. This method
1011          * uses some simple heuristics to discount those cases.
1012          *
1013          * @param string $sql A SQL write query
1014          * @param float $runtime Total runtime, including RTT
1015          */
1016         private function updateTrxWriteQueryTime( $sql, $runtime ) {
1017                 // Whether this is indicative of replica DB runtime (except for RBR or ws_repl)
1018                 $indicativeOfReplicaRuntime = true;
1019                 if ( $runtime > self::SLOW_WRITE_SEC ) {
1020                         $verb = $this->getQueryVerb( $sql );
1021                         // insert(), upsert(), replace() are fast unless bulky in size or blocked on locks
1022                         if ( $verb === 'INSERT' ) {
1023                                 $indicativeOfReplicaRuntime = $this->affectedRows() > self::SMALL_WRITE_ROWS;
1024                         } elseif ( $verb === 'REPLACE' ) {
1025                                 $indicativeOfReplicaRuntime = $this->affectedRows() > self::SMALL_WRITE_ROWS / 2;
1026                         }
1027                 }
1028
1029                 $this->mTrxWriteDuration += $runtime;
1030                 $this->mTrxWriteQueryCount += 1;
1031                 if ( $indicativeOfReplicaRuntime ) {
1032                         $this->mTrxWriteAdjDuration += $runtime;
1033                         $this->mTrxWriteAdjQueryCount += 1;
1034                 }
1035         }
1036
1037         private function canRecoverFromDisconnect( $sql, $priorWritesPending ) {
1038                 # Transaction dropped; this can mean lost writes, or REPEATABLE-READ snapshots.
1039                 # Dropped connections also mean that named locks are automatically released.
1040                 # Only allow error suppression in autocommit mode or when the lost transaction
1041                 # didn't matter anyway (aside from DBO_TRX snapshot loss).
1042                 if ( $this->mNamedLocksHeld ) {
1043                         return false; // possible critical section violation
1044                 } elseif ( $sql === 'COMMIT' ) {
1045                         return !$priorWritesPending; // nothing written anyway? (T127428)
1046                 } elseif ( $sql === 'ROLLBACK' ) {
1047                         return true; // transaction lost...which is also what was requested :)
1048                 } elseif ( $this->explicitTrxActive() ) {
1049                         return false; // don't drop atomocity
1050                 } elseif ( $priorWritesPending ) {
1051                         return false; // prior writes lost from implicit transaction
1052                 }
1053
1054                 return true;
1055         }
1056
1057         private function handleSessionLoss() {
1058                 $this->mTrxLevel = 0;
1059                 $this->mTrxIdleCallbacks = []; // T67263
1060                 $this->mTrxPreCommitCallbacks = []; // T67263
1061                 $this->mSessionTempTables = [];
1062                 $this->mNamedLocksHeld = [];
1063                 try {
1064                         // Handle callbacks in mTrxEndCallbacks
1065                         $this->runOnTransactionIdleCallbacks( self::TRIGGER_ROLLBACK );
1066                         $this->runTransactionListenerCallbacks( self::TRIGGER_ROLLBACK );
1067                         return null;
1068                 } catch ( Exception $e ) {
1069                         // Already logged; move on...
1070                         return $e;
1071                 }
1072         }
1073
1074         public function reportQueryError( $error, $errno, $sql, $fname, $tempIgnore = false ) {
1075                 if ( $this->ignoreErrors() || $tempIgnore ) {
1076                         $this->queryLogger->debug( "SQL ERROR (ignored): $error\n" );
1077                 } else {
1078                         $sql1line = mb_substr( str_replace( "\n", "\\n", $sql ), 0, 5 * 1024 );
1079                         $this->queryLogger->error(
1080                                 "{fname}\t{db_server}\t{errno}\t{error}\t{sql1line}",
1081                                 $this->getLogContext( [
1082                                         'method' => __METHOD__,
1083                                         'errno' => $errno,
1084                                         'error' => $error,
1085                                         'sql1line' => $sql1line,
1086                                         'fname' => $fname,
1087                                 ] )
1088                         );
1089                         $this->queryLogger->debug( "SQL ERROR: " . $error . "\n" );
1090                         throw new DBQueryError( $this, $error, $errno, $sql, $fname );
1091                 }
1092         }
1093
1094         public function freeResult( $res ) {
1095         }
1096
1097         public function selectField(
1098                 $table, $var, $cond = '', $fname = __METHOD__, $options = []
1099         ) {
1100                 if ( $var === '*' ) { // sanity
1101                         throw new DBUnexpectedError( $this, "Cannot use a * field: got '$var'" );
1102                 }
1103
1104                 if ( !is_array( $options ) ) {
1105                         $options = [ $options ];
1106                 }
1107
1108                 $options['LIMIT'] = 1;
1109
1110                 $res = $this->select( $table, $var, $cond, $fname, $options );
1111                 if ( $res === false || !$this->numRows( $res ) ) {
1112                         return false;
1113                 }
1114
1115                 $row = $this->fetchRow( $res );
1116
1117                 if ( $row !== false ) {
1118                         return reset( $row );
1119                 } else {
1120                         return false;
1121                 }
1122         }
1123
1124         public function selectFieldValues(
1125                 $table, $var, $cond = '', $fname = __METHOD__, $options = [], $join_conds = []
1126         ) {
1127                 if ( $var === '*' ) { // sanity
1128                         throw new DBUnexpectedError( $this, "Cannot use a * field" );
1129                 } elseif ( !is_string( $var ) ) { // sanity
1130                         throw new DBUnexpectedError( $this, "Cannot use an array of fields" );
1131                 }
1132
1133                 if ( !is_array( $options ) ) {
1134                         $options = [ $options ];
1135                 }
1136
1137                 $res = $this->select( $table, $var, $cond, $fname, $options, $join_conds );
1138                 if ( $res === false ) {
1139                         return false;
1140                 }
1141
1142                 $values = [];
1143                 foreach ( $res as $row ) {
1144                         $values[] = $row->$var;
1145                 }
1146
1147                 return $values;
1148         }
1149
1150         /**
1151          * Returns an optional USE INDEX clause to go after the table, and a
1152          * string to go at the end of the query.
1153          *
1154          * @param array $options Associative array of options to be turned into
1155          *   an SQL query, valid keys are listed in the function.
1156          * @return array
1157          * @see Database::select()
1158          */
1159         protected function makeSelectOptions( $options ) {
1160                 $preLimitTail = $postLimitTail = '';
1161                 $startOpts = '';
1162
1163                 $noKeyOptions = [];
1164
1165                 foreach ( $options as $key => $option ) {
1166                         if ( is_numeric( $key ) ) {
1167                                 $noKeyOptions[$option] = true;
1168                         }
1169                 }
1170
1171                 $preLimitTail .= $this->makeGroupByWithHaving( $options );
1172
1173                 $preLimitTail .= $this->makeOrderBy( $options );
1174
1175                 if ( isset( $noKeyOptions['FOR UPDATE'] ) ) {
1176                         $postLimitTail .= ' FOR UPDATE';
1177                 }
1178
1179                 if ( isset( $noKeyOptions['LOCK IN SHARE MODE'] ) ) {
1180                         $postLimitTail .= ' LOCK IN SHARE MODE';
1181                 }
1182
1183                 if ( isset( $noKeyOptions['DISTINCT'] ) || isset( $noKeyOptions['DISTINCTROW'] ) ) {
1184                         $startOpts .= 'DISTINCT';
1185                 }
1186
1187                 # Various MySQL extensions
1188                 if ( isset( $noKeyOptions['STRAIGHT_JOIN'] ) ) {
1189                         $startOpts .= ' /*! STRAIGHT_JOIN */';
1190                 }
1191
1192                 if ( isset( $noKeyOptions['HIGH_PRIORITY'] ) ) {
1193                         $startOpts .= ' HIGH_PRIORITY';
1194                 }
1195
1196                 if ( isset( $noKeyOptions['SQL_BIG_RESULT'] ) ) {
1197                         $startOpts .= ' SQL_BIG_RESULT';
1198                 }
1199
1200                 if ( isset( $noKeyOptions['SQL_BUFFER_RESULT'] ) ) {
1201                         $startOpts .= ' SQL_BUFFER_RESULT';
1202                 }
1203
1204                 if ( isset( $noKeyOptions['SQL_SMALL_RESULT'] ) ) {
1205                         $startOpts .= ' SQL_SMALL_RESULT';
1206                 }
1207
1208                 if ( isset( $noKeyOptions['SQL_CALC_FOUND_ROWS'] ) ) {
1209                         $startOpts .= ' SQL_CALC_FOUND_ROWS';
1210                 }
1211
1212                 if ( isset( $noKeyOptions['SQL_CACHE'] ) ) {
1213                         $startOpts .= ' SQL_CACHE';
1214                 }
1215
1216                 if ( isset( $noKeyOptions['SQL_NO_CACHE'] ) ) {
1217                         $startOpts .= ' SQL_NO_CACHE';
1218                 }
1219
1220                 if ( isset( $options['USE INDEX'] ) && is_string( $options['USE INDEX'] ) ) {
1221                         $useIndex = $this->useIndexClause( $options['USE INDEX'] );
1222                 } else {
1223                         $useIndex = '';
1224                 }
1225                 if ( isset( $options['IGNORE INDEX'] ) && is_string( $options['IGNORE INDEX'] ) ) {
1226                         $ignoreIndex = $this->ignoreIndexClause( $options['IGNORE INDEX'] );
1227                 } else {
1228                         $ignoreIndex = '';
1229                 }
1230
1231                 return [ $startOpts, $useIndex, $preLimitTail, $postLimitTail, $ignoreIndex ];
1232         }
1233
1234         /**
1235          * Returns an optional GROUP BY with an optional HAVING
1236          *
1237          * @param array $options Associative array of options
1238          * @return string
1239          * @see Database::select()
1240          * @since 1.21
1241          */
1242         protected function makeGroupByWithHaving( $options ) {
1243                 $sql = '';
1244                 if ( isset( $options['GROUP BY'] ) ) {
1245                         $gb = is_array( $options['GROUP BY'] )
1246                                 ? implode( ',', $options['GROUP BY'] )
1247                                 : $options['GROUP BY'];
1248                         $sql .= ' GROUP BY ' . $gb;
1249                 }
1250                 if ( isset( $options['HAVING'] ) ) {
1251                         $having = is_array( $options['HAVING'] )
1252                                 ? $this->makeList( $options['HAVING'], self::LIST_AND )
1253                                 : $options['HAVING'];
1254                         $sql .= ' HAVING ' . $having;
1255                 }
1256
1257                 return $sql;
1258         }
1259
1260         /**
1261          * Returns an optional ORDER BY
1262          *
1263          * @param array $options Associative array of options
1264          * @return string
1265          * @see Database::select()
1266          * @since 1.21
1267          */
1268         protected function makeOrderBy( $options ) {
1269                 if ( isset( $options['ORDER BY'] ) ) {
1270                         $ob = is_array( $options['ORDER BY'] )
1271                                 ? implode( ',', $options['ORDER BY'] )
1272                                 : $options['ORDER BY'];
1273
1274                         return ' ORDER BY ' . $ob;
1275                 }
1276
1277                 return '';
1278         }
1279
1280         public function select( $table, $vars, $conds = '', $fname = __METHOD__,
1281                 $options = [], $join_conds = [] ) {
1282                 $sql = $this->selectSQLText( $table, $vars, $conds, $fname, $options, $join_conds );
1283
1284                 return $this->query( $sql, $fname );
1285         }
1286
1287         public function selectSQLText( $table, $vars, $conds = '', $fname = __METHOD__,
1288                 $options = [], $join_conds = []
1289         ) {
1290                 if ( is_array( $vars ) ) {
1291                         $vars = implode( ',', $this->fieldNamesWithAlias( $vars ) );
1292                 }
1293
1294                 $options = (array)$options;
1295                 $useIndexes = ( isset( $options['USE INDEX'] ) && is_array( $options['USE INDEX'] ) )
1296                         ? $options['USE INDEX']
1297                         : [];
1298                 $ignoreIndexes = (
1299                         isset( $options['IGNORE INDEX'] ) &&
1300                         is_array( $options['IGNORE INDEX'] )
1301                 )
1302                         ? $options['IGNORE INDEX']
1303                         : [];
1304
1305                 if ( is_array( $table ) ) {
1306                         $from = ' FROM ' .
1307                                 $this->tableNamesWithIndexClauseOrJOIN(
1308                                         $table, $useIndexes, $ignoreIndexes, $join_conds );
1309                 } elseif ( $table != '' ) {
1310                         if ( $table[0] == ' ' ) {
1311                                 $from = ' FROM ' . $table;
1312                         } else {
1313                                 $from = ' FROM ' .
1314                                         $this->tableNamesWithIndexClauseOrJOIN(
1315                                                 [ $table ], $useIndexes, $ignoreIndexes, [] );
1316                         }
1317                 } else {
1318                         $from = '';
1319                 }
1320
1321                 list( $startOpts, $useIndex, $preLimitTail, $postLimitTail, $ignoreIndex ) =
1322                         $this->makeSelectOptions( $options );
1323
1324                 if ( !empty( $conds ) ) {
1325                         if ( is_array( $conds ) ) {
1326                                 $conds = $this->makeList( $conds, self::LIST_AND );
1327                         }
1328                         $sql = "SELECT $startOpts $vars $from $useIndex $ignoreIndex " .
1329                                 "WHERE $conds $preLimitTail";
1330                 } else {
1331                         $sql = "SELECT $startOpts $vars $from $useIndex $ignoreIndex $preLimitTail";
1332                 }
1333
1334                 if ( isset( $options['LIMIT'] ) ) {
1335                         $sql = $this->limitResult( $sql, $options['LIMIT'],
1336                                 isset( $options['OFFSET'] ) ? $options['OFFSET'] : false );
1337                 }
1338                 $sql = "$sql $postLimitTail";
1339
1340                 if ( isset( $options['EXPLAIN'] ) ) {
1341                         $sql = 'EXPLAIN ' . $sql;
1342                 }
1343
1344                 return $sql;
1345         }
1346
1347         public function selectRow( $table, $vars, $conds, $fname = __METHOD__,
1348                 $options = [], $join_conds = []
1349         ) {
1350                 $options = (array)$options;
1351                 $options['LIMIT'] = 1;
1352                 $res = $this->select( $table, $vars, $conds, $fname, $options, $join_conds );
1353
1354                 if ( $res === false ) {
1355                         return false;
1356                 }
1357
1358                 if ( !$this->numRows( $res ) ) {
1359                         return false;
1360                 }
1361
1362                 $obj = $this->fetchObject( $res );
1363
1364                 return $obj;
1365         }
1366
1367         public function estimateRowCount(
1368                 $table, $vars = '*', $conds = '', $fname = __METHOD__, $options = []
1369         ) {
1370                 $rows = 0;
1371                 $res = $this->select( $table, [ 'rowcount' => 'COUNT(*)' ], $conds, $fname, $options );
1372
1373                 if ( $res ) {
1374                         $row = $this->fetchRow( $res );
1375                         $rows = ( isset( $row['rowcount'] ) ) ? (int)$row['rowcount'] : 0;
1376                 }
1377
1378                 return $rows;
1379         }
1380
1381         public function selectRowCount(
1382                 $tables, $vars = '*', $conds = '', $fname = __METHOD__, $options = [], $join_conds = []
1383         ) {
1384                 $rows = 0;
1385                 $sql = $this->selectSQLText( $tables, '1', $conds, $fname, $options, $join_conds );
1386                 // The identifier quotes is primarily for MSSQL.
1387                 $rowCountCol = $this->addIdentifierQuotes( "rowcount" );
1388                 $tableName = $this->addIdentifierQuotes( "tmp_count" );
1389                 $res = $this->query( "SELECT COUNT(*) AS $rowCountCol FROM ($sql) $tableName", $fname );
1390
1391                 if ( $res ) {
1392                         $row = $this->fetchRow( $res );
1393                         $rows = ( isset( $row['rowcount'] ) ) ? (int)$row['rowcount'] : 0;
1394                 }
1395
1396                 return $rows;
1397         }
1398
1399         /**
1400          * Removes most variables from an SQL query and replaces them with X or N for numbers.
1401          * It's only slightly flawed. Don't use for anything important.
1402          *
1403          * @param string $sql A SQL Query
1404          *
1405          * @return string
1406          */
1407         protected static function generalizeSQL( $sql ) {
1408                 # This does the same as the regexp below would do, but in such a way
1409                 # as to avoid crashing php on some large strings.
1410                 # $sql = preg_replace( "/'([^\\\\']|\\\\.)*'|\"([^\\\\\"]|\\\\.)*\"/", "'X'", $sql );
1411
1412                 $sql = str_replace( "\\\\", '', $sql );
1413                 $sql = str_replace( "\\'", '', $sql );
1414                 $sql = str_replace( "\\\"", '', $sql );
1415                 $sql = preg_replace( "/'.*'/s", "'X'", $sql );
1416                 $sql = preg_replace( '/".*"/s', "'X'", $sql );
1417
1418                 # All newlines, tabs, etc replaced by single space
1419                 $sql = preg_replace( '/\s+/', ' ', $sql );
1420
1421                 # All numbers => N,
1422                 # except the ones surrounded by characters, e.g. l10n
1423                 $sql = preg_replace( '/-?\d+(,-?\d+)+/s', 'N,...,N', $sql );
1424                 $sql = preg_replace( '/(?<![a-zA-Z])-?\d+(?![a-zA-Z])/s', 'N', $sql );
1425
1426                 return $sql;
1427         }
1428
1429         public function fieldExists( $table, $field, $fname = __METHOD__ ) {
1430                 $info = $this->fieldInfo( $table, $field );
1431
1432                 return (bool)$info;
1433         }
1434
1435         public function indexExists( $table, $index, $fname = __METHOD__ ) {
1436                 if ( !$this->tableExists( $table ) ) {
1437                         return null;
1438                 }
1439
1440                 $info = $this->indexInfo( $table, $index, $fname );
1441                 if ( is_null( $info ) ) {
1442                         return null;
1443                 } else {
1444                         return $info !== false;
1445                 }
1446         }
1447
1448         public function tableExists( $table, $fname = __METHOD__ ) {
1449                 $tableRaw = $this->tableName( $table, 'raw' );
1450                 if ( isset( $this->mSessionTempTables[$tableRaw] ) ) {
1451                         return true; // already known to exist
1452                 }
1453
1454                 $table = $this->tableName( $table );
1455                 $ignoreErrors = true;
1456                 $res = $this->query( "SELECT 1 FROM $table LIMIT 1", $fname, $ignoreErrors );
1457
1458                 return (bool)$res;
1459         }
1460
1461         public function indexUnique( $table, $index ) {
1462                 $indexInfo = $this->indexInfo( $table, $index );
1463
1464                 if ( !$indexInfo ) {
1465                         return null;
1466                 }
1467
1468                 return !$indexInfo[0]->Non_unique;
1469         }
1470
1471         /**
1472          * Helper for Database::insert().
1473          *
1474          * @param array $options
1475          * @return string
1476          */
1477         protected function makeInsertOptions( $options ) {
1478                 return implode( ' ', $options );
1479         }
1480
1481         public function insert( $table, $a, $fname = __METHOD__, $options = [] ) {
1482                 # No rows to insert, easy just return now
1483                 if ( !count( $a ) ) {
1484                         return true;
1485                 }
1486
1487                 $table = $this->tableName( $table );
1488
1489                 if ( !is_array( $options ) ) {
1490                         $options = [ $options ];
1491                 }
1492
1493                 $fh = null;
1494                 if ( isset( $options['fileHandle'] ) ) {
1495                         $fh = $options['fileHandle'];
1496                 }
1497                 $options = $this->makeInsertOptions( $options );
1498
1499                 if ( isset( $a[0] ) && is_array( $a[0] ) ) {
1500                         $multi = true;
1501                         $keys = array_keys( $a[0] );
1502                 } else {
1503                         $multi = false;
1504                         $keys = array_keys( $a );
1505                 }
1506
1507                 $sql = 'INSERT ' . $options .
1508                         " INTO $table (" . implode( ',', $keys ) . ') VALUES ';
1509
1510                 if ( $multi ) {
1511                         $first = true;
1512                         foreach ( $a as $row ) {
1513                                 if ( $first ) {
1514                                         $first = false;
1515                                 } else {
1516                                         $sql .= ',';
1517                                 }
1518                                 $sql .= '(' . $this->makeList( $row ) . ')';
1519                         }
1520                 } else {
1521                         $sql .= '(' . $this->makeList( $a ) . ')';
1522                 }
1523
1524                 if ( $fh !== null && false === fwrite( $fh, $sql ) ) {
1525                         return false;
1526                 } elseif ( $fh !== null ) {
1527                         return true;
1528                 }
1529
1530                 return (bool)$this->query( $sql, $fname );
1531         }
1532
1533         /**
1534          * Make UPDATE options array for Database::makeUpdateOptions
1535          *
1536          * @param array $options
1537          * @return array
1538          */
1539         protected function makeUpdateOptionsArray( $options ) {
1540                 if ( !is_array( $options ) ) {
1541                         $options = [ $options ];
1542                 }
1543
1544                 $opts = [];
1545
1546                 if ( in_array( 'IGNORE', $options ) ) {
1547                         $opts[] = 'IGNORE';
1548                 }
1549
1550                 return $opts;
1551         }
1552
1553         /**
1554          * Make UPDATE options for the Database::update function
1555          *
1556          * @param array $options The options passed to Database::update
1557          * @return string
1558          */
1559         protected function makeUpdateOptions( $options ) {
1560                 $opts = $this->makeUpdateOptionsArray( $options );
1561
1562                 return implode( ' ', $opts );
1563         }
1564
1565         public function update( $table, $values, $conds, $fname = __METHOD__, $options = [] ) {
1566                 $table = $this->tableName( $table );
1567                 $opts = $this->makeUpdateOptions( $options );
1568                 $sql = "UPDATE $opts $table SET " . $this->makeList( $values, self::LIST_SET );
1569
1570                 if ( $conds !== [] && $conds !== '*' ) {
1571                         $sql .= " WHERE " . $this->makeList( $conds, self::LIST_AND );
1572                 }
1573
1574                 return (bool)$this->query( $sql, $fname );
1575         }
1576
1577         public function makeList( $a, $mode = self::LIST_COMMA ) {
1578                 if ( !is_array( $a ) ) {
1579                         throw new DBUnexpectedError( $this, __METHOD__ . ' called with incorrect parameters' );
1580                 }
1581
1582                 $first = true;
1583                 $list = '';
1584
1585                 foreach ( $a as $field => $value ) {
1586                         if ( !$first ) {
1587                                 if ( $mode == self::LIST_AND ) {
1588                                         $list .= ' AND ';
1589                                 } elseif ( $mode == self::LIST_OR ) {
1590                                         $list .= ' OR ';
1591                                 } else {
1592                                         $list .= ',';
1593                                 }
1594                         } else {
1595                                 $first = false;
1596                         }
1597
1598                         if ( ( $mode == self::LIST_AND || $mode == self::LIST_OR ) && is_numeric( $field ) ) {
1599                                 $list .= "($value)";
1600                         } elseif ( $mode == self::LIST_SET && is_numeric( $field ) ) {
1601                                 $list .= "$value";
1602                         } elseif (
1603                                 ( $mode == self::LIST_AND || $mode == self::LIST_OR ) && is_array( $value )
1604                         ) {
1605                                 // Remove null from array to be handled separately if found
1606                                 $includeNull = false;
1607                                 foreach ( array_keys( $value, null, true ) as $nullKey ) {
1608                                         $includeNull = true;
1609                                         unset( $value[$nullKey] );
1610                                 }
1611                                 if ( count( $value ) == 0 && !$includeNull ) {
1612                                         throw new InvalidArgumentException(
1613                                                 __METHOD__ . ": empty input for field $field" );
1614                                 } elseif ( count( $value ) == 0 ) {
1615                                         // only check if $field is null
1616                                         $list .= "$field IS NULL";
1617                                 } else {
1618                                         // IN clause contains at least one valid element
1619                                         if ( $includeNull ) {
1620                                                 // Group subconditions to ensure correct precedence
1621                                                 $list .= '(';
1622                                         }
1623                                         if ( count( $value ) == 1 ) {
1624                                                 // Special-case single values, as IN isn't terribly efficient
1625                                                 // Don't necessarily assume the single key is 0; we don't
1626                                                 // enforce linear numeric ordering on other arrays here.
1627                                                 $value = array_values( $value )[0];
1628                                                 $list .= $field . " = " . $this->addQuotes( $value );
1629                                         } else {
1630                                                 $list .= $field . " IN (" . $this->makeList( $value ) . ") ";
1631                                         }
1632                                         // if null present in array, append IS NULL
1633                                         if ( $includeNull ) {
1634                                                 $list .= " OR $field IS NULL)";
1635                                         }
1636                                 }
1637                         } elseif ( $value === null ) {
1638                                 if ( $mode == self::LIST_AND || $mode == self::LIST_OR ) {
1639                                         $list .= "$field IS ";
1640                                 } elseif ( $mode == self::LIST_SET ) {
1641                                         $list .= "$field = ";
1642                                 }
1643                                 $list .= 'NULL';
1644                         } else {
1645                                 if (
1646                                         $mode == self::LIST_AND || $mode == self::LIST_OR || $mode == self::LIST_SET
1647                                 ) {
1648                                         $list .= "$field = ";
1649                                 }
1650                                 $list .= $mode == self::LIST_NAMES ? $value : $this->addQuotes( $value );
1651                         }
1652                 }
1653
1654                 return $list;
1655         }
1656
1657         public function makeWhereFrom2d( $data, $baseKey, $subKey ) {
1658                 $conds = [];
1659
1660                 foreach ( $data as $base => $sub ) {
1661                         if ( count( $sub ) ) {
1662                                 $conds[] = $this->makeList(
1663                                         [ $baseKey => $base, $subKey => array_keys( $sub ) ],
1664                                         self::LIST_AND );
1665                         }
1666                 }
1667
1668                 if ( $conds ) {
1669                         return $this->makeList( $conds, self::LIST_OR );
1670                 } else {
1671                         // Nothing to search for...
1672                         return false;
1673                 }
1674         }
1675
1676         public function aggregateValue( $valuedata, $valuename = 'value' ) {
1677                 return $valuename;
1678         }
1679
1680         public function bitNot( $field ) {
1681                 return "(~$field)";
1682         }
1683
1684         public function bitAnd( $fieldLeft, $fieldRight ) {
1685                 return "($fieldLeft & $fieldRight)";
1686         }
1687
1688         public function bitOr( $fieldLeft, $fieldRight ) {
1689                 return "($fieldLeft | $fieldRight)";
1690         }
1691
1692         public function buildConcat( $stringList ) {
1693                 return 'CONCAT(' . implode( ',', $stringList ) . ')';
1694         }
1695
1696         public function buildGroupConcatField(
1697                 $delim, $table, $field, $conds = '', $join_conds = []
1698         ) {
1699                 $fld = "GROUP_CONCAT($field SEPARATOR " . $this->addQuotes( $delim ) . ')';
1700
1701                 return '(' . $this->selectSQLText( $table, $fld, $conds, null, [], $join_conds ) . ')';
1702         }
1703
1704         public function buildStringCast( $field ) {
1705                 return $field;
1706         }
1707
1708         public function selectDB( $db ) {
1709                 # Stub. Shouldn't cause serious problems if it's not overridden, but
1710                 # if your database engine supports a concept similar to MySQL's
1711                 # databases you may as well.
1712                 $this->mDBname = $db;
1713
1714                 return true;
1715         }
1716
1717         public function getDBname() {
1718                 return $this->mDBname;
1719         }
1720
1721         public function getServer() {
1722                 return $this->mServer;
1723         }
1724
1725         public function tableName( $name, $format = 'quoted' ) {
1726                 # Skip the entire process when we have a string quoted on both ends.
1727                 # Note that we check the end so that we will still quote any use of
1728                 # use of `database`.table. But won't break things if someone wants
1729                 # to query a database table with a dot in the name.
1730                 if ( $this->isQuotedIdentifier( $name ) ) {
1731                         return $name;
1732                 }
1733
1734                 # Lets test for any bits of text that should never show up in a table
1735                 # name. Basically anything like JOIN or ON which are actually part of
1736                 # SQL queries, but may end up inside of the table value to combine
1737                 # sql. Such as how the API is doing.
1738                 # Note that we use a whitespace test rather than a \b test to avoid
1739                 # any remote case where a word like on may be inside of a table name
1740                 # surrounded by symbols which may be considered word breaks.
1741                 if ( preg_match( '/(^|\s)(DISTINCT|JOIN|ON|AS)(\s|$)/i', $name ) !== 0 ) {
1742                         return $name;
1743                 }
1744
1745                 # Split database and table into proper variables.
1746                 # We reverse the explode so that database.table and table both output
1747                 # the correct table.
1748                 $dbDetails = explode( '.', $name, 3 );
1749                 if ( count( $dbDetails ) == 3 ) {
1750                         list( $database, $schema, $table ) = $dbDetails;
1751                         # We don't want any prefix added in this case
1752                         $prefix = '';
1753                 } elseif ( count( $dbDetails ) == 2 ) {
1754                         list( $database, $table ) = $dbDetails;
1755                         # We don't want any prefix added in this case
1756                         $prefix = '';
1757                         # In dbs that support it, $database may actually be the schema
1758                         # but that doesn't affect any of the functionality here
1759                         $schema = '';
1760                 } else {
1761                         list( $table ) = $dbDetails;
1762                         if ( isset( $this->tableAliases[$table] ) ) {
1763                                 $database = $this->tableAliases[$table]['dbname'];
1764                                 $schema = is_string( $this->tableAliases[$table]['schema'] )
1765                                         ? $this->tableAliases[$table]['schema']
1766                                         : $this->mSchema;
1767                                 $prefix = is_string( $this->tableAliases[$table]['prefix'] )
1768                                         ? $this->tableAliases[$table]['prefix']
1769                                         : $this->mTablePrefix;
1770                         } else {
1771                                 $database = '';
1772                                 $schema = $this->mSchema; # Default schema
1773                                 $prefix = $this->mTablePrefix; # Default prefix
1774                         }
1775                 }
1776
1777                 # Quote $table and apply the prefix if not quoted.
1778                 # $tableName might be empty if this is called from Database::replaceVars()
1779                 $tableName = "{$prefix}{$table}";
1780                 if ( $format === 'quoted'
1781                         && !$this->isQuotedIdentifier( $tableName )
1782                         && $tableName !== ''
1783                 ) {
1784                         $tableName = $this->addIdentifierQuotes( $tableName );
1785                 }
1786
1787                 # Quote $schema and $database and merge them with the table name if needed
1788                 $tableName = $this->prependDatabaseOrSchema( $schema, $tableName, $format );
1789                 $tableName = $this->prependDatabaseOrSchema( $database, $tableName, $format );
1790
1791                 return $tableName;
1792         }
1793
1794         /**
1795          * @param string|null $namespace Database or schema
1796          * @param string $relation Name of table, view, sequence, etc...
1797          * @param string $format One of (raw, quoted)
1798          * @return string Relation name with quoted and merged $namespace as needed
1799          */
1800         private function prependDatabaseOrSchema( $namespace, $relation, $format ) {
1801                 if ( strlen( $namespace ) ) {
1802                         if ( $format === 'quoted' && !$this->isQuotedIdentifier( $namespace ) ) {
1803                                 $namespace = $this->addIdentifierQuotes( $namespace );
1804                         }
1805                         $relation = $namespace . '.' . $relation;
1806                 }
1807
1808                 return $relation;
1809         }
1810
1811         public function tableNames() {
1812                 $inArray = func_get_args();
1813                 $retVal = [];
1814
1815                 foreach ( $inArray as $name ) {
1816                         $retVal[$name] = $this->tableName( $name );
1817                 }
1818
1819                 return $retVal;
1820         }
1821
1822         public function tableNamesN() {
1823                 $inArray = func_get_args();
1824                 $retVal = [];
1825
1826                 foreach ( $inArray as $name ) {
1827                         $retVal[] = $this->tableName( $name );
1828                 }
1829
1830                 return $retVal;
1831         }
1832
1833         /**
1834          * Get an aliased table name
1835          * e.g. tableName AS newTableName
1836          *
1837          * @param string $name Table name, see tableName()
1838          * @param string|bool $alias Alias (optional)
1839          * @return string SQL name for aliased table. Will not alias a table to its own name
1840          */
1841         protected function tableNameWithAlias( $name, $alias = false ) {
1842                 if ( !$alias || $alias == $name ) {
1843                         return $this->tableName( $name );
1844                 } else {
1845                         return $this->tableName( $name ) . ' ' . $this->addIdentifierQuotes( $alias );
1846                 }
1847         }
1848
1849         /**
1850          * Gets an array of aliased table names
1851          *
1852          * @param array $tables [ [alias] => table ]
1853          * @return string[] See tableNameWithAlias()
1854          */
1855         protected function tableNamesWithAlias( $tables ) {
1856                 $retval = [];
1857                 foreach ( $tables as $alias => $table ) {
1858                         if ( is_numeric( $alias ) ) {
1859                                 $alias = $table;
1860                         }
1861                         $retval[] = $this->tableNameWithAlias( $table, $alias );
1862                 }
1863
1864                 return $retval;
1865         }
1866
1867         /**
1868          * Get an aliased field name
1869          * e.g. fieldName AS newFieldName
1870          *
1871          * @param string $name Field name
1872          * @param string|bool $alias Alias (optional)
1873          * @return string SQL name for aliased field. Will not alias a field to its own name
1874          */
1875         protected function fieldNameWithAlias( $name, $alias = false ) {
1876                 if ( !$alias || (string)$alias === (string)$name ) {
1877                         return $name;
1878                 } else {
1879                         return $name . ' AS ' . $this->addIdentifierQuotes( $alias ); // PostgreSQL needs AS
1880                 }
1881         }
1882
1883         /**
1884          * Gets an array of aliased field names
1885          *
1886          * @param array $fields [ [alias] => field ]
1887          * @return string[] See fieldNameWithAlias()
1888          */
1889         protected function fieldNamesWithAlias( $fields ) {
1890                 $retval = [];
1891                 foreach ( $fields as $alias => $field ) {
1892                         if ( is_numeric( $alias ) ) {
1893                                 $alias = $field;
1894                         }
1895                         $retval[] = $this->fieldNameWithAlias( $field, $alias );
1896                 }
1897
1898                 return $retval;
1899         }
1900
1901         /**
1902          * Get the aliased table name clause for a FROM clause
1903          * which might have a JOIN and/or USE INDEX or IGNORE INDEX clause
1904          *
1905          * @param array $tables ( [alias] => table )
1906          * @param array $use_index Same as for select()
1907          * @param array $ignore_index Same as for select()
1908          * @param array $join_conds Same as for select()
1909          * @return string
1910          */
1911         protected function tableNamesWithIndexClauseOrJOIN(
1912                 $tables, $use_index = [], $ignore_index = [], $join_conds = []
1913         ) {
1914                 $ret = [];
1915                 $retJOIN = [];
1916                 $use_index = (array)$use_index;
1917                 $ignore_index = (array)$ignore_index;
1918                 $join_conds = (array)$join_conds;
1919
1920                 foreach ( $tables as $alias => $table ) {
1921                         if ( !is_string( $alias ) ) {
1922                                 // No alias? Set it equal to the table name
1923                                 $alias = $table;
1924                         }
1925                         // Is there a JOIN clause for this table?
1926                         if ( isset( $join_conds[$alias] ) ) {
1927                                 list( $joinType, $conds ) = $join_conds[$alias];
1928                                 $tableClause = $joinType;
1929                                 $tableClause .= ' ' . $this->tableNameWithAlias( $table, $alias );
1930                                 if ( isset( $use_index[$alias] ) ) { // has USE INDEX?
1931                                         $use = $this->useIndexClause( implode( ',', (array)$use_index[$alias] ) );
1932                                         if ( $use != '' ) {
1933                                                 $tableClause .= ' ' . $use;
1934                                         }
1935                                 }
1936                                 if ( isset( $ignore_index[$alias] ) ) { // has IGNORE INDEX?
1937                                         $ignore = $this->ignoreIndexClause(
1938                                                 implode( ',', (array)$ignore_index[$alias] ) );
1939                                         if ( $ignore != '' ) {
1940                                                 $tableClause .= ' ' . $ignore;
1941                                         }
1942                                 }
1943                                 $on = $this->makeList( (array)$conds, self::LIST_AND );
1944                                 if ( $on != '' ) {
1945                                         $tableClause .= ' ON (' . $on . ')';
1946                                 }
1947
1948                                 $retJOIN[] = $tableClause;
1949                         } elseif ( isset( $use_index[$alias] ) ) {
1950                                 // Is there an INDEX clause for this table?
1951                                 $tableClause = $this->tableNameWithAlias( $table, $alias );
1952                                 $tableClause .= ' ' . $this->useIndexClause(
1953                                                 implode( ',', (array)$use_index[$alias] )
1954                                         );
1955
1956                                 $ret[] = $tableClause;
1957                         } elseif ( isset( $ignore_index[$alias] ) ) {
1958                                 // Is there an INDEX clause for this table?
1959                                 $tableClause = $this->tableNameWithAlias( $table, $alias );
1960                                 $tableClause .= ' ' . $this->ignoreIndexClause(
1961                                                 implode( ',', (array)$ignore_index[$alias] )
1962                                         );
1963
1964                                 $ret[] = $tableClause;
1965                         } else {
1966                                 $tableClause = $this->tableNameWithAlias( $table, $alias );
1967
1968                                 $ret[] = $tableClause;
1969                         }
1970                 }
1971
1972                 // We can't separate explicit JOIN clauses with ',', use ' ' for those
1973                 $implicitJoins = !empty( $ret ) ? implode( ',', $ret ) : "";
1974                 $explicitJoins = !empty( $retJOIN ) ? implode( ' ', $retJOIN ) : "";
1975
1976                 // Compile our final table clause
1977                 return implode( ' ', [ $implicitJoins, $explicitJoins ] );
1978         }
1979
1980         /**
1981          * Allows for index remapping in queries where this is not consistent across DBMS
1982          *
1983          * @param string $index
1984          * @return string
1985          */
1986         protected function indexName( $index ) {
1987                 return $index;
1988         }
1989
1990         public function addQuotes( $s ) {
1991                 if ( $s instanceof Blob ) {
1992                         $s = $s->fetch();
1993                 }
1994                 if ( $s === null ) {
1995                         return 'NULL';
1996                 } elseif ( is_bool( $s ) ) {
1997                         return (int)$s;
1998                 } else {
1999                         # This will also quote numeric values. This should be harmless,
2000                         # and protects against weird problems that occur when they really
2001                         # _are_ strings such as article titles and string->number->string
2002                         # conversion is not 1:1.
2003                         return "'" . $this->strencode( $s ) . "'";
2004                 }
2005         }
2006
2007         /**
2008          * Quotes an identifier using `backticks` or "double quotes" depending on the database type.
2009          * MySQL uses `backticks` while basically everything else uses double quotes.
2010          * Since MySQL is the odd one out here the double quotes are our generic
2011          * and we implement backticks in DatabaseMysql.
2012          *
2013          * @param string $s
2014          * @return string
2015          */
2016         public function addIdentifierQuotes( $s ) {
2017                 return '"' . str_replace( '"', '""', $s ) . '"';
2018         }
2019
2020         /**
2021          * Returns if the given identifier looks quoted or not according to
2022          * the database convention for quoting identifiers .
2023          *
2024          * @note Do not use this to determine if untrusted input is safe.
2025          *   A malicious user can trick this function.
2026          * @param string $name
2027          * @return bool
2028          */
2029         public function isQuotedIdentifier( $name ) {
2030                 return $name[0] == '"' && substr( $name, -1, 1 ) == '"';
2031         }
2032
2033         /**
2034          * @param string $s
2035          * @return string
2036          */
2037         protected function escapeLikeInternal( $s, $escapeChar = '`' ) {
2038                 return str_replace( [ $escapeChar, '%', '_' ],
2039                         [ "{$escapeChar}{$escapeChar}", "{$escapeChar}%", "{$escapeChar}_" ],
2040                         $s );
2041         }
2042
2043         public function buildLike() {
2044                 $params = func_get_args();
2045
2046                 if ( count( $params ) > 0 && is_array( $params[0] ) ) {
2047                         $params = $params[0];
2048                 }
2049
2050                 $s = '';
2051
2052                 // We use ` instead of \ as the default LIKE escape character, since addQuotes()
2053                 // may escape backslashes, creating problems of double escaping. The `
2054                 // character has good cross-DBMS compatibility, avoiding special operators
2055                 // in MS SQL like ^ and %
2056                 $escapeChar = '`';
2057
2058                 foreach ( $params as $value ) {
2059                         if ( $value instanceof LikeMatch ) {
2060                                 $s .= $value->toString();
2061                         } else {
2062                                 $s .= $this->escapeLikeInternal( $value, $escapeChar );
2063                         }
2064                 }
2065
2066                 return ' LIKE ' . $this->addQuotes( $s ) . ' ESCAPE ' . $this->addQuotes( $escapeChar ) . ' ';
2067         }
2068
2069         public function anyChar() {
2070                 return new LikeMatch( '_' );
2071         }
2072
2073         public function anyString() {
2074                 return new LikeMatch( '%' );
2075         }
2076
2077         public function nextSequenceValue( $seqName ) {
2078                 return null;
2079         }
2080
2081         /**
2082          * USE 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 useIndexClause( $index ) {
2092                 return '';
2093         }
2094
2095         /**
2096          * IGNORE INDEX clause. Unlikely to be useful for anything but MySQL. This
2097          * is only needed because a) MySQL must be as efficient as possible due to
2098          * its use on Wikipedia, and b) MySQL 4.0 is kind of dumb sometimes about
2099          * which index to pick. Anyway, other databases might have different
2100          * indexes on a given table. So don't bother overriding this unless you're
2101          * MySQL.
2102          * @param string $index
2103          * @return string
2104          */
2105         public function ignoreIndexClause( $index ) {
2106                 return '';
2107         }
2108
2109         public function replace( $table, $uniqueIndexes, $rows, $fname = __METHOD__ ) {
2110                 $quotedTable = $this->tableName( $table );
2111
2112                 if ( count( $rows ) == 0 ) {
2113                         return;
2114                 }
2115
2116                 # Single row case
2117                 if ( !is_array( reset( $rows ) ) ) {
2118                         $rows = [ $rows ];
2119                 }
2120
2121                 // @FXIME: this is not atomic, but a trx would break affectedRows()
2122                 foreach ( $rows as $row ) {
2123                         # Delete rows which collide
2124                         if ( $uniqueIndexes ) {
2125                                 $sql = "DELETE FROM $quotedTable WHERE ";
2126                                 $first = true;
2127                                 foreach ( $uniqueIndexes as $index ) {
2128                                         if ( $first ) {
2129                                                 $first = false;
2130                                                 $sql .= '( ';
2131                                         } else {
2132                                                 $sql .= ' ) OR ( ';
2133                                         }
2134                                         if ( is_array( $index ) ) {
2135                                                 $first2 = true;
2136                                                 foreach ( $index as $col ) {
2137                                                         if ( $first2 ) {
2138                                                                 $first2 = false;
2139                                                         } else {
2140                                                                 $sql .= ' AND ';
2141                                                         }
2142                                                         $sql .= $col . '=' . $this->addQuotes( $row[$col] );
2143                                                 }
2144                                         } else {
2145                                                 $sql .= $index . '=' . $this->addQuotes( $row[$index] );
2146                                         }
2147                                 }
2148                                 $sql .= ' )';
2149                                 $this->query( $sql, $fname );
2150                         }
2151
2152                         # Now insert the row
2153                         $this->insert( $table, $row, $fname );
2154                 }
2155         }
2156
2157         /**
2158          * REPLACE query wrapper for MySQL and SQLite, which have a native REPLACE
2159          * statement.
2160          *
2161          * @param string $table Table name
2162          * @param array|string $rows Row(s) to insert
2163          * @param string $fname Caller function name
2164          *
2165          * @return ResultWrapper
2166          */
2167         protected function nativeReplace( $table, $rows, $fname ) {
2168                 $table = $this->tableName( $table );
2169
2170                 # Single row case
2171                 if ( !is_array( reset( $rows ) ) ) {
2172                         $rows = [ $rows ];
2173                 }
2174
2175                 $sql = "REPLACE INTO $table (" . implode( ',', array_keys( $rows[0] ) ) . ') VALUES ';
2176                 $first = true;
2177
2178                 foreach ( $rows as $row ) {
2179                         if ( $first ) {
2180                                 $first = false;
2181                         } else {
2182                                 $sql .= ',';
2183                         }
2184
2185                         $sql .= '(' . $this->makeList( $row ) . ')';
2186                 }
2187
2188                 return $this->query( $sql, $fname );
2189         }
2190
2191         public function upsert( $table, array $rows, array $uniqueIndexes, array $set,
2192                 $fname = __METHOD__
2193         ) {
2194                 if ( !count( $rows ) ) {
2195                         return true; // nothing to do
2196                 }
2197
2198                 if ( !is_array( reset( $rows ) ) ) {
2199                         $rows = [ $rows ];
2200                 }
2201
2202                 if ( count( $uniqueIndexes ) ) {
2203                         $clauses = []; // list WHERE clauses that each identify a single row
2204                         foreach ( $rows as $row ) {
2205                                 foreach ( $uniqueIndexes as $index ) {
2206                                         $index = is_array( $index ) ? $index : [ $index ]; // columns
2207                                         $rowKey = []; // unique key to this row
2208                                         foreach ( $index as $column ) {
2209                                                 $rowKey[$column] = $row[$column];
2210                                         }
2211                                         $clauses[] = $this->makeList( $rowKey, self::LIST_AND );
2212                                 }
2213                         }
2214                         $where = [ $this->makeList( $clauses, self::LIST_OR ) ];
2215                 } else {
2216                         $where = false;
2217                 }
2218
2219                 $useTrx = !$this->mTrxLevel;
2220                 if ( $useTrx ) {
2221                         $this->begin( $fname, self::TRANSACTION_INTERNAL );
2222                 }
2223                 try {
2224                         # Update any existing conflicting row(s)
2225                         if ( $where !== false ) {
2226                                 $ok = $this->update( $table, $set, $where, $fname );
2227                         } else {
2228                                 $ok = true;
2229                         }
2230                         # Now insert any non-conflicting row(s)
2231                         $ok = $this->insert( $table, $rows, $fname, [ 'IGNORE' ] ) && $ok;
2232                 } catch ( Exception $e ) {
2233                         if ( $useTrx ) {
2234                                 $this->rollback( $fname, self::FLUSHING_INTERNAL );
2235                         }
2236                         throw $e;
2237                 }
2238                 if ( $useTrx ) {
2239                         $this->commit( $fname, self::FLUSHING_INTERNAL );
2240                 }
2241
2242                 return $ok;
2243         }
2244
2245         public function deleteJoin( $delTable, $joinTable, $delVar, $joinVar, $conds,
2246                 $fname = __METHOD__
2247         ) {
2248                 if ( !$conds ) {
2249                         throw new DBUnexpectedError( $this, __METHOD__ . ' called with empty $conds' );
2250                 }
2251
2252                 $delTable = $this->tableName( $delTable );
2253                 $joinTable = $this->tableName( $joinTable );
2254                 $sql = "DELETE FROM $delTable WHERE $delVar IN (SELECT $joinVar FROM $joinTable ";
2255                 if ( $conds != '*' ) {
2256                         $sql .= 'WHERE ' . $this->makeList( $conds, self::LIST_AND );
2257                 }
2258                 $sql .= ')';
2259
2260                 $this->query( $sql, $fname );
2261         }
2262
2263         public function textFieldSize( $table, $field ) {
2264                 $table = $this->tableName( $table );
2265                 $sql = "SHOW COLUMNS FROM $table LIKE \"$field\";";
2266                 $res = $this->query( $sql, __METHOD__ );
2267                 $row = $this->fetchObject( $res );
2268
2269                 $m = [];
2270
2271                 if ( preg_match( '/\((.*)\)/', $row->Type, $m ) ) {
2272                         $size = $m[1];
2273                 } else {
2274                         $size = -1;
2275                 }
2276
2277                 return $size;
2278         }
2279
2280         public function delete( $table, $conds, $fname = __METHOD__ ) {
2281                 if ( !$conds ) {
2282                         throw new DBUnexpectedError( $this, __METHOD__ . ' called with no conditions' );
2283                 }
2284
2285                 $table = $this->tableName( $table );
2286                 $sql = "DELETE FROM $table";
2287
2288                 if ( $conds != '*' ) {
2289                         if ( is_array( $conds ) ) {
2290                                 $conds = $this->makeList( $conds, self::LIST_AND );
2291                         }
2292                         $sql .= ' WHERE ' . $conds;
2293                 }
2294
2295                 return $this->query( $sql, $fname );
2296         }
2297
2298         public function insertSelect(
2299                 $destTable, $srcTable, $varMap, $conds,
2300                 $fname = __METHOD__, $insertOptions = [], $selectOptions = []
2301         ) {
2302                 if ( $this->cliMode ) {
2303                         // For massive migrations with downtime, we don't want to select everything
2304                         // into memory and OOM, so do all this native on the server side if possible.
2305                         return $this->nativeInsertSelect(
2306                                 $destTable,
2307                                 $srcTable,
2308                                 $varMap,
2309                                 $conds,
2310                                 $fname,
2311                                 $insertOptions,
2312                                 $selectOptions
2313                         );
2314                 }
2315
2316                 // For web requests, do a locking SELECT and then INSERT. This puts the SELECT burden
2317                 // on only the master (without needing row-based-replication). It also makes it easy to
2318                 // know how big the INSERT is going to be.
2319                 $fields = [];
2320                 foreach ( $varMap as $dstColumn => $sourceColumnOrSql ) {
2321                         $fields[] = $this->fieldNameWithAlias( $sourceColumnOrSql, $dstColumn );
2322                 }
2323                 $selectOptions[] = 'FOR UPDATE';
2324                 $res = $this->select( $srcTable, implode( ',', $fields ), $conds, $fname, $selectOptions );
2325                 if ( !$res ) {
2326                         return false;
2327                 }
2328
2329                 $rows = [];
2330                 foreach ( $res as $row ) {
2331                         $rows[] = (array)$row;
2332                 }
2333
2334                 return $this->insert( $destTable, $rows, $fname, $insertOptions );
2335         }
2336
2337         protected function nativeInsertSelect( $destTable, $srcTable, $varMap, $conds,
2338                 $fname = __METHOD__,
2339                 $insertOptions = [], $selectOptions = []
2340         ) {
2341                 $destTable = $this->tableName( $destTable );
2342
2343                 if ( !is_array( $insertOptions ) ) {
2344                         $insertOptions = [ $insertOptions ];
2345                 }
2346
2347                 $insertOptions = $this->makeInsertOptions( $insertOptions );
2348
2349                 if ( !is_array( $selectOptions ) ) {
2350                         $selectOptions = [ $selectOptions ];
2351                 }
2352
2353                 list( $startOpts, $useIndex, $tailOpts, $ignoreIndex ) = $this->makeSelectOptions(
2354                         $selectOptions );
2355
2356                 if ( is_array( $srcTable ) ) {
2357                         $srcTable = implode( ',', array_map( [ $this, 'tableName' ], $srcTable ) );
2358                 } else {
2359                         $srcTable = $this->tableName( $srcTable );
2360                 }
2361
2362                 $sql = "INSERT $insertOptions" .
2363                         " INTO $destTable (" . implode( ',', array_keys( $varMap ) ) . ')' .
2364                         " SELECT $startOpts " . implode( ',', $varMap ) .
2365                         " FROM $srcTable $useIndex $ignoreIndex ";
2366
2367                 if ( $conds != '*' ) {
2368                         if ( is_array( $conds ) ) {
2369                                 $conds = $this->makeList( $conds, self::LIST_AND );
2370                         }
2371                         $sql .= " WHERE $conds";
2372                 }
2373
2374                 $sql .= " $tailOpts";
2375
2376                 return $this->query( $sql, $fname );
2377         }
2378
2379         /**
2380          * Construct a LIMIT query with optional offset. This is used for query
2381          * pages. The SQL should be adjusted so that only the first $limit rows
2382          * are returned. If $offset is provided as well, then the first $offset
2383          * rows should be discarded, and the next $limit rows should be returned.
2384          * If the result of the query is not ordered, then the rows to be returned
2385          * are theoretically arbitrary.
2386          *
2387          * $sql is expected to be a SELECT, if that makes a difference.
2388          *
2389          * The version provided by default works in MySQL and SQLite. It will very
2390          * likely need to be overridden for most other DBMSes.
2391          *
2392          * @param string $sql SQL query we will append the limit too
2393          * @param int $limit The SQL limit
2394          * @param int|bool $offset The SQL offset (default false)
2395          * @throws DBUnexpectedError
2396          * @return string
2397          */
2398         public function limitResult( $sql, $limit, $offset = false ) {
2399                 if ( !is_numeric( $limit ) ) {
2400                         throw new DBUnexpectedError( $this,
2401                                 "Invalid non-numeric limit passed to limitResult()\n" );
2402                 }
2403
2404                 return "$sql LIMIT "
2405                 . ( ( is_numeric( $offset ) && $offset != 0 ) ? "{$offset}," : "" )
2406                 . "{$limit} ";
2407         }
2408
2409         public function unionSupportsOrderAndLimit() {
2410                 return true; // True for almost every DB supported
2411         }
2412
2413         public function unionQueries( $sqls, $all ) {
2414                 $glue = $all ? ') UNION ALL (' : ') UNION (';
2415
2416                 return '(' . implode( $glue, $sqls ) . ')';
2417         }
2418
2419         public function conditional( $cond, $trueVal, $falseVal ) {
2420                 if ( is_array( $cond ) ) {
2421                         $cond = $this->makeList( $cond, self::LIST_AND );
2422                 }
2423
2424                 return " (CASE WHEN $cond THEN $trueVal ELSE $falseVal END) ";
2425         }
2426
2427         public function strreplace( $orig, $old, $new ) {
2428                 return "REPLACE({$orig}, {$old}, {$new})";
2429         }
2430
2431         public function getServerUptime() {
2432                 return 0;
2433         }
2434
2435         public function wasDeadlock() {
2436                 return false;
2437         }
2438
2439         public function wasLockTimeout() {
2440                 return false;
2441         }
2442
2443         public function wasErrorReissuable() {
2444                 return false;
2445         }
2446
2447         public function wasReadOnlyError() {
2448                 return false;
2449         }
2450
2451         /**
2452          * Do not use this method outside of Database/DBError classes
2453          *
2454          * @param integer|string $errno
2455          * @return bool Whether the given query error was a connection drop
2456          */
2457         public function wasConnectionError( $errno ) {
2458                 return false;
2459         }
2460
2461         public function deadlockLoop() {
2462                 $args = func_get_args();
2463                 $function = array_shift( $args );
2464                 $tries = self::DEADLOCK_TRIES;
2465
2466                 $this->begin( __METHOD__ );
2467
2468                 $retVal = null;
2469                 /** @var Exception $e */
2470                 $e = null;
2471                 do {
2472                         try {
2473                                 $retVal = call_user_func_array( $function, $args );
2474                                 break;
2475                         } catch ( DBQueryError $e ) {
2476                                 if ( $this->wasDeadlock() ) {
2477                                         // Retry after a randomized delay
2478                                         usleep( mt_rand( self::DEADLOCK_DELAY_MIN, self::DEADLOCK_DELAY_MAX ) );
2479                                 } else {
2480                                         // Throw the error back up
2481                                         throw $e;
2482                                 }
2483                         }
2484                 } while ( --$tries > 0 );
2485
2486                 if ( $tries <= 0 ) {
2487                         // Too many deadlocks; give up
2488                         $this->rollback( __METHOD__ );
2489                         throw $e;
2490                 } else {
2491                         $this->commit( __METHOD__ );
2492
2493                         return $retVal;
2494                 }
2495         }
2496
2497         public function masterPosWait( DBMasterPos $pos, $timeout ) {
2498                 # Real waits are implemented in the subclass.
2499                 return 0;
2500         }
2501
2502         public function getReplicaPos() {
2503                 # Stub
2504                 return false;
2505         }
2506
2507         public function getMasterPos() {
2508                 # Stub
2509                 return false;
2510         }
2511
2512         public function serverIsReadOnly() {
2513                 return false;
2514         }
2515
2516         final public function onTransactionResolution( callable $callback, $fname = __METHOD__ ) {
2517                 if ( !$this->mTrxLevel ) {
2518                         throw new DBUnexpectedError( $this, "No transaction is active." );
2519                 }
2520                 $this->mTrxEndCallbacks[] = [ $callback, $fname ];
2521         }
2522
2523         final public function onTransactionIdle( callable $callback, $fname = __METHOD__ ) {
2524                 $this->mTrxIdleCallbacks[] = [ $callback, $fname ];
2525                 if ( !$this->mTrxLevel ) {
2526                         $this->runOnTransactionIdleCallbacks( self::TRIGGER_IDLE );
2527                 }
2528         }
2529
2530         final public function onTransactionPreCommitOrIdle( callable $callback, $fname = __METHOD__ ) {
2531                 if ( $this->mTrxLevel ) {
2532                         $this->mTrxPreCommitCallbacks[] = [ $callback, $fname ];
2533                 } else {
2534                         // If no transaction is active, then make one for this callback
2535                         $this->startAtomic( __METHOD__ );
2536                         try {
2537                                 call_user_func( $callback );
2538                                 $this->endAtomic( __METHOD__ );
2539                         } catch ( Exception $e ) {
2540                                 $this->rollback( __METHOD__, self::FLUSHING_INTERNAL );
2541                                 throw $e;
2542                         }
2543                 }
2544         }
2545
2546         final public function setTransactionListener( $name, callable $callback = null ) {
2547                 if ( $callback ) {
2548                         $this->mTrxRecurringCallbacks[$name] = $callback;
2549                 } else {
2550                         unset( $this->mTrxRecurringCallbacks[$name] );
2551                 }
2552         }
2553
2554         /**
2555          * Whether to disable running of post-COMMIT/ROLLBACK callbacks
2556          *
2557          * This method should not be used outside of Database/LoadBalancer
2558          *
2559          * @param bool $suppress
2560          * @since 1.28
2561          */
2562         final public function setTrxEndCallbackSuppression( $suppress ) {
2563                 $this->mTrxEndCallbacksSuppressed = $suppress;
2564         }
2565
2566         /**
2567          * Actually run and consume any "on transaction idle/resolution" callbacks.
2568          *
2569          * This method should not be used outside of Database/LoadBalancer
2570          *
2571          * @param integer $trigger IDatabase::TRIGGER_* constant
2572          * @since 1.20
2573          * @throws Exception
2574          */
2575         public function runOnTransactionIdleCallbacks( $trigger ) {
2576                 if ( $this->mTrxEndCallbacksSuppressed ) {
2577                         return;
2578                 }
2579
2580                 $autoTrx = $this->getFlag( self::DBO_TRX ); // automatic begin() enabled?
2581                 /** @var Exception $e */
2582                 $e = null; // first exception
2583                 do { // callbacks may add callbacks :)
2584                         $callbacks = array_merge(
2585                                 $this->mTrxIdleCallbacks,
2586                                 $this->mTrxEndCallbacks // include "transaction resolution" callbacks
2587                         );
2588                         $this->mTrxIdleCallbacks = []; // consumed (and recursion guard)
2589                         $this->mTrxEndCallbacks = []; // consumed (recursion guard)
2590                         foreach ( $callbacks as $callback ) {
2591                                 try {
2592                                         list( $phpCallback ) = $callback;
2593                                         $this->clearFlag( self::DBO_TRX ); // make each query its own transaction
2594                                         call_user_func_array( $phpCallback, [ $trigger ] );
2595                                         if ( $autoTrx ) {
2596                                                 $this->setFlag( self::DBO_TRX ); // restore automatic begin()
2597                                         } else {
2598                                                 $this->clearFlag( self::DBO_TRX ); // restore auto-commit
2599                                         }
2600                                 } catch ( Exception $ex ) {
2601                                         call_user_func( $this->errorLogger, $ex );
2602                                         $e = $e ?: $ex;
2603                                         // Some callbacks may use startAtomic/endAtomic, so make sure
2604                                         // their transactions are ended so other callbacks don't fail
2605                                         if ( $this->trxLevel() ) {
2606                                                 $this->rollback( __METHOD__, self::FLUSHING_INTERNAL );
2607                                         }
2608                                 }
2609                         }
2610                 } while ( count( $this->mTrxIdleCallbacks ) );
2611
2612                 if ( $e instanceof Exception ) {
2613                         throw $e; // re-throw any first exception
2614                 }
2615         }
2616
2617         /**
2618          * Actually run and consume any "on transaction pre-commit" callbacks.
2619          *
2620          * This method should not be used outside of Database/LoadBalancer
2621          *
2622          * @since 1.22
2623          * @throws Exception
2624          */
2625         public function runOnTransactionPreCommitCallbacks() {
2626                 $e = null; // first exception
2627                 do { // callbacks may add callbacks :)
2628                         $callbacks = $this->mTrxPreCommitCallbacks;
2629                         $this->mTrxPreCommitCallbacks = []; // consumed (and recursion guard)
2630                         foreach ( $callbacks as $callback ) {
2631                                 try {
2632                                         list( $phpCallback ) = $callback;
2633                                         call_user_func( $phpCallback );
2634                                 } catch ( Exception $ex ) {
2635                                         call_user_func( $this->errorLogger, $ex );
2636                                         $e = $e ?: $ex;
2637                                 }
2638                         }
2639                 } while ( count( $this->mTrxPreCommitCallbacks ) );
2640
2641                 if ( $e instanceof Exception ) {
2642                         throw $e; // re-throw any first exception
2643                 }
2644         }
2645
2646         /**
2647          * Actually run any "transaction listener" callbacks.
2648          *
2649          * This method should not be used outside of Database/LoadBalancer
2650          *
2651          * @param integer $trigger IDatabase::TRIGGER_* constant
2652          * @throws Exception
2653          * @since 1.20
2654          */
2655         public function runTransactionListenerCallbacks( $trigger ) {
2656                 if ( $this->mTrxEndCallbacksSuppressed ) {
2657                         return;
2658                 }
2659
2660                 /** @var Exception $e */
2661                 $e = null; // first exception
2662
2663                 foreach ( $this->mTrxRecurringCallbacks as $phpCallback ) {
2664                         try {
2665                                 $phpCallback( $trigger, $this );
2666                         } catch ( Exception $ex ) {
2667                                 call_user_func( $this->errorLogger, $ex );
2668                                 $e = $e ?: $ex;
2669                         }
2670                 }
2671
2672                 if ( $e instanceof Exception ) {
2673                         throw $e; // re-throw any first exception
2674                 }
2675         }
2676
2677         final public function startAtomic( $fname = __METHOD__ ) {
2678                 if ( !$this->mTrxLevel ) {
2679                         $this->begin( $fname, self::TRANSACTION_INTERNAL );
2680                         // If DBO_TRX is set, a series of startAtomic/endAtomic pairs will result
2681                         // in all changes being in one transaction to keep requests transactional.
2682                         if ( !$this->getFlag( self::DBO_TRX ) ) {
2683                                 $this->mTrxAutomaticAtomic = true;
2684                         }
2685                 }
2686
2687                 $this->mTrxAtomicLevels[] = $fname;
2688         }
2689
2690         final public function endAtomic( $fname = __METHOD__ ) {
2691                 if ( !$this->mTrxLevel ) {
2692                         throw new DBUnexpectedError( $this, "No atomic transaction is open (got $fname)." );
2693                 }
2694                 if ( !$this->mTrxAtomicLevels ||
2695                         array_pop( $this->mTrxAtomicLevels ) !== $fname
2696                 ) {
2697                         throw new DBUnexpectedError( $this, "Invalid atomic section ended (got $fname)." );
2698                 }
2699
2700                 if ( !$this->mTrxAtomicLevels && $this->mTrxAutomaticAtomic ) {
2701                         $this->commit( $fname, self::FLUSHING_INTERNAL );
2702                 }
2703         }
2704
2705         final public function doAtomicSection( $fname, callable $callback ) {
2706                 $this->startAtomic( $fname );
2707                 try {
2708                         $res = call_user_func_array( $callback, [ $this, $fname ] );
2709                 } catch ( Exception $e ) {
2710                         $this->rollback( $fname, self::FLUSHING_INTERNAL );
2711                         throw $e;
2712                 }
2713                 $this->endAtomic( $fname );
2714
2715                 return $res;
2716         }
2717
2718         final public function begin( $fname = __METHOD__, $mode = self::TRANSACTION_EXPLICIT ) {
2719                 // Protect against mismatched atomic section, transaction nesting, and snapshot loss
2720                 if ( $this->mTrxLevel ) {
2721                         if ( $this->mTrxAtomicLevels ) {
2722                                 $levels = implode( ', ', $this->mTrxAtomicLevels );
2723                                 $msg = "$fname: Got explicit BEGIN while atomic section(s) $levels are open.";
2724                                 throw new DBUnexpectedError( $this, $msg );
2725                         } elseif ( !$this->mTrxAutomatic ) {
2726                                 $msg = "$fname: Explicit transaction already active (from {$this->mTrxFname}).";
2727                                 throw new DBUnexpectedError( $this, $msg );
2728                         } else {
2729                                 // @TODO: make this an exception at some point
2730                                 $msg = "$fname: Implicit transaction already active (from {$this->mTrxFname}).";
2731                                 $this->queryLogger->error( $msg );
2732                                 return; // join the main transaction set
2733                         }
2734                 } elseif ( $this->getFlag( self::DBO_TRX ) && $mode !== self::TRANSACTION_INTERNAL ) {
2735                         // @TODO: make this an exception at some point
2736                         $msg = "$fname: Implicit transaction expected (DBO_TRX set).";
2737                         $this->queryLogger->error( $msg );
2738                         return; // let any writes be in the main transaction
2739                 }
2740
2741                 // Avoid fatals if close() was called
2742                 $this->assertOpen();
2743
2744                 $this->doBegin( $fname );
2745                 $this->mTrxTimestamp = microtime( true );
2746                 $this->mTrxFname = $fname;
2747                 $this->mTrxDoneWrites = false;
2748                 $this->mTrxAutomaticAtomic = false;
2749                 $this->mTrxAtomicLevels = [];
2750                 $this->mTrxShortId = sprintf( '%06x', mt_rand( 0, 0xffffff ) );
2751                 $this->mTrxWriteDuration = 0.0;
2752                 $this->mTrxWriteQueryCount = 0;
2753                 $this->mTrxWriteAdjDuration = 0.0;
2754                 $this->mTrxWriteAdjQueryCount = 0;
2755                 $this->mTrxWriteCallers = [];
2756                 // First SELECT after BEGIN will establish the snapshot in REPEATABLE-READ.
2757                 // Get an estimate of the replica DB lag before then, treating estimate staleness
2758                 // as lag itself just to be safe
2759                 $status = $this->getApproximateLagStatus();
2760                 $this->mTrxReplicaLag = $status['lag'] + ( microtime( true ) - $status['since'] );
2761                 // T147697: make explicitTrxActive() return true until begin() finishes. This way, no
2762                 // caller will think its OK to muck around with the transaction just because startAtomic()
2763                 // has not yet completed (e.g. setting mTrxAtomicLevels).
2764                 $this->mTrxAutomatic = ( $mode === self::TRANSACTION_INTERNAL );
2765         }
2766
2767         /**
2768          * Issues the BEGIN command to the database server.
2769          *
2770          * @see Database::begin()
2771          * @param string $fname
2772          */
2773         protected function doBegin( $fname ) {
2774                 $this->query( 'BEGIN', $fname );
2775                 $this->mTrxLevel = 1;
2776         }
2777
2778         final public function commit( $fname = __METHOD__, $flush = '' ) {
2779                 if ( $this->mTrxLevel && $this->mTrxAtomicLevels ) {
2780                         // There are still atomic sections open. This cannot be ignored
2781                         $levels = implode( ', ', $this->mTrxAtomicLevels );
2782                         throw new DBUnexpectedError(
2783                                 $this,
2784                                 "$fname: Got COMMIT while atomic sections $levels are still open."
2785                         );
2786                 }
2787
2788                 if ( $flush === self::FLUSHING_INTERNAL || $flush === self::FLUSHING_ALL_PEERS ) {
2789                         if ( !$this->mTrxLevel ) {
2790                                 return; // nothing to do
2791                         } elseif ( !$this->mTrxAutomatic ) {
2792                                 throw new DBUnexpectedError(
2793                                         $this,
2794                                         "$fname: Flushing an explicit transaction, getting out of sync."
2795                                 );
2796                         }
2797                 } else {
2798                         if ( !$this->mTrxLevel ) {
2799                                 $this->queryLogger->error(
2800                                         "$fname: No transaction to commit, something got out of sync." );
2801                                 return; // nothing to do
2802                         } elseif ( $this->mTrxAutomatic ) {
2803                                 // @TODO: make this an exception at some point
2804                                 $msg = "$fname: Explicit commit of implicit transaction.";
2805                                 $this->queryLogger->error( $msg );
2806                                 return; // wait for the main transaction set commit round
2807                         }
2808                 }
2809
2810                 // Avoid fatals if close() was called
2811                 $this->assertOpen();
2812
2813                 $this->runOnTransactionPreCommitCallbacks();
2814                 $writeTime = $this->pendingWriteQueryDuration( self::ESTIMATE_DB_APPLY );
2815                 $this->doCommit( $fname );
2816                 if ( $this->mTrxDoneWrites ) {
2817                         $this->mLastWriteTime = microtime( true );
2818                         $this->trxProfiler->transactionWritingOut(
2819                                 $this->mServer, $this->mDBname, $this->mTrxShortId, $writeTime );
2820                 }
2821
2822                 $this->runOnTransactionIdleCallbacks( self::TRIGGER_COMMIT );
2823                 $this->runTransactionListenerCallbacks( self::TRIGGER_COMMIT );
2824         }
2825
2826         /**
2827          * Issues the COMMIT command to the database server.
2828          *
2829          * @see Database::commit()
2830          * @param string $fname
2831          */
2832         protected function doCommit( $fname ) {
2833                 if ( $this->mTrxLevel ) {
2834                         $this->query( 'COMMIT', $fname );
2835                         $this->mTrxLevel = 0;
2836                 }
2837         }
2838
2839         final public function rollback( $fname = __METHOD__, $flush = '' ) {
2840                 if ( $flush === self::FLUSHING_INTERNAL || $flush === self::FLUSHING_ALL_PEERS ) {
2841                         if ( !$this->mTrxLevel ) {
2842                                 return; // nothing to do
2843                         }
2844                 } else {
2845                         if ( !$this->mTrxLevel ) {
2846                                 $this->queryLogger->error(
2847                                         "$fname: No transaction to rollback, something got out of sync." );
2848                                 return; // nothing to do
2849                         } elseif ( $this->getFlag( self::DBO_TRX ) ) {
2850                                 throw new DBUnexpectedError(
2851                                         $this,
2852                                         "$fname: Expected mass rollback of all peer databases (DBO_TRX set)."
2853                                 );
2854                         }
2855                 }
2856
2857                 // Avoid fatals if close() was called
2858                 $this->assertOpen();
2859
2860                 $this->doRollback( $fname );
2861                 $this->mTrxAtomicLevels = [];
2862                 if ( $this->mTrxDoneWrites ) {
2863                         $this->trxProfiler->transactionWritingOut(
2864                                 $this->mServer, $this->mDBname, $this->mTrxShortId );
2865                 }
2866
2867                 $this->mTrxIdleCallbacks = []; // clear
2868                 $this->mTrxPreCommitCallbacks = []; // clear
2869                 $this->runOnTransactionIdleCallbacks( self::TRIGGER_ROLLBACK );
2870                 $this->runTransactionListenerCallbacks( self::TRIGGER_ROLLBACK );
2871         }
2872
2873         /**
2874          * Issues the ROLLBACK command to the database server.
2875          *
2876          * @see Database::rollback()
2877          * @param string $fname
2878          */
2879         protected function doRollback( $fname ) {
2880                 if ( $this->mTrxLevel ) {
2881                         # Disconnects cause rollback anyway, so ignore those errors
2882                         $ignoreErrors = true;
2883                         $this->query( 'ROLLBACK', $fname, $ignoreErrors );
2884                         $this->mTrxLevel = 0;
2885                 }
2886         }
2887
2888         public function flushSnapshot( $fname = __METHOD__ ) {
2889                 if ( $this->writesOrCallbacksPending() || $this->explicitTrxActive() ) {
2890                         // This only flushes transactions to clear snapshots, not to write data
2891                         $fnames = implode( ', ', $this->pendingWriteAndCallbackCallers() );
2892                         throw new DBUnexpectedError(
2893                                 $this,
2894                                 "$fname: Cannot flush snapshot because writes are pending ($fnames)."
2895                         );
2896                 }
2897
2898                 $this->commit( $fname, self::FLUSHING_INTERNAL );
2899         }
2900
2901         public function explicitTrxActive() {
2902                 return $this->mTrxLevel && ( $this->mTrxAtomicLevels || !$this->mTrxAutomatic );
2903         }
2904
2905         public function duplicateTableStructure(
2906                 $oldName, $newName, $temporary = false, $fname = __METHOD__
2907         ) {
2908                 throw new RuntimeException( __METHOD__ . ' is not implemented in descendant class' );
2909         }
2910
2911         public function listTables( $prefix = null, $fname = __METHOD__ ) {
2912                 throw new RuntimeException( __METHOD__ . ' is not implemented in descendant class' );
2913         }
2914
2915         public function listViews( $prefix = null, $fname = __METHOD__ ) {
2916                 throw new RuntimeException( __METHOD__ . ' is not implemented in descendant class' );
2917         }
2918
2919         public function timestamp( $ts = 0 ) {
2920                 $t = new ConvertibleTimestamp( $ts );
2921                 // Let errors bubble up to avoid putting garbage in the DB
2922                 return $t->getTimestamp( TS_MW );
2923         }
2924
2925         public function timestampOrNull( $ts = null ) {
2926                 if ( is_null( $ts ) ) {
2927                         return null;
2928                 } else {
2929                         return $this->timestamp( $ts );
2930                 }
2931         }
2932
2933         /**
2934          * Take the result from a query, and wrap it in a ResultWrapper if
2935          * necessary. Boolean values are passed through as is, to indicate success
2936          * of write queries or failure.
2937          *
2938          * Once upon a time, Database::query() returned a bare MySQL result
2939          * resource, and it was necessary to call this function to convert it to
2940          * a wrapper. Nowadays, raw database objects are never exposed to external
2941          * callers, so this is unnecessary in external code.
2942          *
2943          * @param bool|ResultWrapper|resource|object $result
2944          * @return bool|ResultWrapper
2945          */
2946         protected function resultObject( $result ) {
2947                 if ( !$result ) {
2948                         return false;
2949                 } elseif ( $result instanceof ResultWrapper ) {
2950                         return $result;
2951                 } elseif ( $result === true ) {
2952                         // Successful write query
2953                         return $result;
2954                 } else {
2955                         return new ResultWrapper( $this, $result );
2956                 }
2957         }
2958
2959         public function ping( &$rtt = null ) {
2960                 // Avoid hitting the server if it was hit recently
2961                 if ( $this->isOpen() && ( microtime( true ) - $this->lastPing ) < self::PING_TTL ) {
2962                         if ( !func_num_args() || $this->mRTTEstimate > 0 ) {
2963                                 $rtt = $this->mRTTEstimate;
2964                                 return true; // don't care about $rtt
2965                         }
2966                 }
2967
2968                 // This will reconnect if possible or return false if not
2969                 $this->clearFlag( self::DBO_TRX, self::REMEMBER_PRIOR );
2970                 $ok = ( $this->query( self::PING_QUERY, __METHOD__, true ) !== false );
2971                 $this->restoreFlags( self::RESTORE_PRIOR );
2972
2973                 if ( $ok ) {
2974                         $rtt = $this->mRTTEstimate;
2975                 }
2976
2977                 return $ok;
2978         }
2979
2980         /**
2981          * @return bool
2982          */
2983         protected function reconnect() {
2984                 $this->closeConnection();
2985                 $this->mOpened = false;
2986                 $this->mConn = false;
2987                 try {
2988                         $this->open( $this->mServer, $this->mUser, $this->mPassword, $this->mDBname );
2989                         $this->lastPing = microtime( true );
2990                         $ok = true;
2991                 } catch ( DBConnectionError $e ) {
2992                         $ok = false;
2993                 }
2994
2995                 return $ok;
2996         }
2997
2998         public function getSessionLagStatus() {
2999                 return $this->getTransactionLagStatus() ?: $this->getApproximateLagStatus();
3000         }
3001
3002         /**
3003          * Get the replica DB lag when the current transaction started
3004          *
3005          * This is useful when transactions might use snapshot isolation
3006          * (e.g. REPEATABLE-READ in innodb), so the "real" lag of that data
3007          * is this lag plus transaction duration. If they don't, it is still
3008          * safe to be pessimistic. This returns null if there is no transaction.
3009          *
3010          * @return array|null ('lag': seconds or false on error, 'since': UNIX timestamp of BEGIN)
3011          * @since 1.27
3012          */
3013         protected function getTransactionLagStatus() {
3014                 return $this->mTrxLevel
3015                         ? [ 'lag' => $this->mTrxReplicaLag, 'since' => $this->trxTimestamp() ]
3016                         : null;
3017         }
3018
3019         /**
3020          * Get a replica DB lag estimate for this server
3021          *
3022          * @return array ('lag': seconds or false on error, 'since': UNIX timestamp of estimate)
3023          * @since 1.27
3024          */
3025         protected function getApproximateLagStatus() {
3026                 return [
3027                         'lag'   => $this->getLBInfo( 'replica' ) ? $this->getLag() : 0,
3028                         'since' => microtime( true )
3029                 ];
3030         }
3031
3032         /**
3033          * Merge the result of getSessionLagStatus() for several DBs
3034          * using the most pessimistic values to estimate the lag of
3035          * any data derived from them in combination
3036          *
3037          * This is information is useful for caching modules
3038          *
3039          * @see WANObjectCache::set()
3040          * @see WANObjectCache::getWithSetCallback()
3041          *
3042          * @param IDatabase $db1
3043          * @param IDatabase ...
3044          * @return array Map of values:
3045          *   - lag: highest lag of any of the DBs or false on error (e.g. replication stopped)
3046          *   - since: oldest UNIX timestamp of any of the DB lag estimates
3047          *   - pending: whether any of the DBs have uncommitted changes
3048          * @since 1.27
3049          */
3050         public static function getCacheSetOptions( IDatabase $db1 ) {
3051                 $res = [ 'lag' => 0, 'since' => INF, 'pending' => false ];
3052                 foreach ( func_get_args() as $db ) {
3053                         /** @var IDatabase $db */
3054                         $status = $db->getSessionLagStatus();
3055                         if ( $status['lag'] === false ) {
3056                                 $res['lag'] = false;
3057                         } elseif ( $res['lag'] !== false ) {
3058                                 $res['lag'] = max( $res['lag'], $status['lag'] );
3059                         }
3060                         $res['since'] = min( $res['since'], $status['since'] );
3061                         $res['pending'] = $res['pending'] ?: $db->writesPending();
3062                 }
3063
3064                 return $res;
3065         }
3066
3067         public function getLag() {
3068                 return 0;
3069         }
3070
3071         public function maxListLen() {
3072                 return 0;
3073         }
3074
3075         public function encodeBlob( $b ) {
3076                 return $b;
3077         }
3078
3079         public function decodeBlob( $b ) {
3080                 if ( $b instanceof Blob ) {
3081                         $b = $b->fetch();
3082                 }
3083                 return $b;
3084         }
3085
3086         public function setSessionOptions( array $options ) {
3087         }
3088
3089         public function sourceFile(
3090                 $filename,
3091                 callable $lineCallback = null,
3092                 callable $resultCallback = null,
3093                 $fname = false,
3094                 callable $inputCallback = null
3095         ) {
3096                 MediaWiki\suppressWarnings();
3097                 $fp = fopen( $filename, 'r' );
3098                 MediaWiki\restoreWarnings();
3099
3100                 if ( false === $fp ) {
3101                         throw new RuntimeException( "Could not open \"{$filename}\".\n" );
3102                 }
3103
3104                 if ( !$fname ) {
3105                         $fname = __METHOD__ . "( $filename )";
3106                 }
3107
3108                 try {
3109                         $error = $this->sourceStream(
3110                                 $fp, $lineCallback, $resultCallback, $fname, $inputCallback );
3111                 } catch ( Exception $e ) {
3112                         fclose( $fp );
3113                         throw $e;
3114                 }
3115
3116                 fclose( $fp );
3117
3118                 return $error;
3119         }
3120
3121         public function setSchemaVars( $vars ) {
3122                 $this->mSchemaVars = $vars;
3123         }
3124
3125         public function sourceStream(
3126                 $fp,
3127                 callable $lineCallback = null,
3128                 callable $resultCallback = null,
3129                 $fname = __METHOD__,
3130                 callable $inputCallback = null
3131         ) {
3132                 $cmd = '';
3133
3134                 while ( !feof( $fp ) ) {
3135                         if ( $lineCallback ) {
3136                                 call_user_func( $lineCallback );
3137                         }
3138
3139                         $line = trim( fgets( $fp ) );
3140
3141                         if ( $line == '' ) {
3142                                 continue;
3143                         }
3144
3145                         if ( '-' == $line[0] && '-' == $line[1] ) {
3146                                 continue;
3147                         }
3148
3149                         if ( $cmd != '' ) {
3150                                 $cmd .= ' ';
3151                         }
3152
3153                         $done = $this->streamStatementEnd( $cmd, $line );
3154
3155                         $cmd .= "$line\n";
3156
3157                         if ( $done || feof( $fp ) ) {
3158                                 $cmd = $this->replaceVars( $cmd );
3159
3160                                 if ( !$inputCallback || call_user_func( $inputCallback, $cmd ) ) {
3161                                         $res = $this->query( $cmd, $fname );
3162
3163                                         if ( $resultCallback ) {
3164                                                 call_user_func( $resultCallback, $res, $this );
3165                                         }
3166
3167                                         if ( false === $res ) {
3168                                                 $err = $this->lastError();
3169
3170                                                 return "Query \"{$cmd}\" failed with error code \"$err\".\n";
3171                                         }
3172                                 }
3173                                 $cmd = '';
3174                         }
3175                 }
3176
3177                 return true;
3178         }
3179
3180         /**
3181          * Called by sourceStream() to check if we've reached a statement end
3182          *
3183          * @param string &$sql SQL assembled so far
3184          * @param string &$newLine New line about to be added to $sql
3185          * @return bool Whether $newLine contains end of the statement
3186          */
3187         public function streamStatementEnd( &$sql, &$newLine ) {
3188                 if ( $this->delimiter ) {
3189                         $prev = $newLine;
3190                         $newLine = preg_replace(
3191                                 '/' . preg_quote( $this->delimiter, '/' ) . '$/', '', $newLine );
3192                         if ( $newLine != $prev ) {
3193                                 return true;
3194                         }
3195                 }
3196
3197                 return false;
3198         }
3199
3200         /**
3201          * Database independent variable replacement. Replaces a set of variables
3202          * in an SQL statement with their contents as given by $this->getSchemaVars().
3203          *
3204          * Supports '{$var}' `{$var}` and / *$var* / (without the spaces) style variables.
3205          *
3206          * - '{$var}' should be used for text and is passed through the database's
3207          *   addQuotes method.
3208          * - `{$var}` should be used for identifiers (e.g. table and database names).
3209          *   It is passed through the database's addIdentifierQuotes method which
3210          *   can be overridden if the database uses something other than backticks.
3211          * - / *_* / or / *$wgDBprefix* / passes the name that follows through the
3212          *   database's tableName method.
3213          * - / *i* / passes the name that follows through the database's indexName method.
3214          * - In all other cases, / *$var* / is left unencoded. Except for table options,
3215          *   its use should be avoided. In 1.24 and older, string encoding was applied.
3216          *
3217          * @param string $ins SQL statement to replace variables in
3218          * @return string The new SQL statement with variables replaced
3219          */
3220         protected function replaceVars( $ins ) {
3221                 $vars = $this->getSchemaVars();
3222                 return preg_replace_callback(
3223                         '!
3224                                 /\* (\$wgDBprefix|[_i]) \*/ (\w*) | # 1-2. tableName, indexName
3225                                 \'\{\$ (\w+) }\'                  | # 3. addQuotes
3226                                 `\{\$ (\w+) }`                    | # 4. addIdentifierQuotes
3227                                 /\*\$ (\w+) \*/                     # 5. leave unencoded
3228                         !x',
3229                         function ( $m ) use ( $vars ) {
3230                                 // Note: Because of <https://bugs.php.net/bug.php?id=51881>,
3231                                 // check for both nonexistent keys *and* the empty string.
3232                                 if ( isset( $m[1] ) && $m[1] !== '' ) {
3233                                         if ( $m[1] === 'i' ) {
3234                                                 return $this->indexName( $m[2] );
3235                                         } else {
3236                                                 return $this->tableName( $m[2] );
3237                                         }
3238                                 } elseif ( isset( $m[3] ) && $m[3] !== '' && array_key_exists( $m[3], $vars ) ) {
3239                                         return $this->addQuotes( $vars[$m[3]] );
3240                                 } elseif ( isset( $m[4] ) && $m[4] !== '' && array_key_exists( $m[4], $vars ) ) {
3241                                         return $this->addIdentifierQuotes( $vars[$m[4]] );
3242                                 } elseif ( isset( $m[5] ) && $m[5] !== '' && array_key_exists( $m[5], $vars ) ) {
3243                                         return $vars[$m[5]];
3244                                 } else {
3245                                         return $m[0];
3246                                 }
3247                         },
3248                         $ins
3249                 );
3250         }
3251
3252         /**
3253          * Get schema variables. If none have been set via setSchemaVars(), then
3254          * use some defaults from the current object.
3255          *
3256          * @return array
3257          */
3258         protected function getSchemaVars() {
3259                 if ( $this->mSchemaVars ) {
3260                         return $this->mSchemaVars;
3261                 } else {
3262                         return $this->getDefaultSchemaVars();
3263                 }
3264         }
3265
3266         /**
3267          * Get schema variables to use if none have been set via setSchemaVars().
3268          *
3269          * Override this in derived classes to provide variables for tables.sql
3270          * and SQL patch files.
3271          *
3272          * @return array
3273          */
3274         protected function getDefaultSchemaVars() {
3275                 return [];
3276         }
3277
3278         public function lockIsFree( $lockName, $method ) {
3279                 return true;
3280         }
3281
3282         public function lock( $lockName, $method, $timeout = 5 ) {
3283                 $this->mNamedLocksHeld[$lockName] = 1;
3284
3285                 return true;
3286         }
3287
3288         public function unlock( $lockName, $method ) {
3289                 unset( $this->mNamedLocksHeld[$lockName] );
3290
3291                 return true;
3292         }
3293
3294         public function getScopedLockAndFlush( $lockKey, $fname, $timeout ) {
3295                 if ( $this->writesOrCallbacksPending() ) {
3296                         // This only flushes transactions to clear snapshots, not to write data
3297                         $fnames = implode( ', ', $this->pendingWriteAndCallbackCallers() );
3298                         throw new DBUnexpectedError(
3299                                 $this,
3300                                 "$fname: Cannot flush pre-lock snapshot because writes are pending ($fnames)."
3301                         );
3302                 }
3303
3304                 if ( !$this->lock( $lockKey, $fname, $timeout ) ) {
3305                         return null;
3306                 }
3307
3308                 $unlocker = new ScopedCallback( function () use ( $lockKey, $fname ) {
3309                         if ( $this->trxLevel() ) {
3310                                 // There is a good chance an exception was thrown, causing any early return
3311                                 // from the caller. Let any error handler get a chance to issue rollback().
3312                                 // If there isn't one, let the error bubble up and trigger server-side rollback.
3313                                 $this->onTransactionResolution(
3314                                         function () use ( $lockKey, $fname ) {
3315                                                 $this->unlock( $lockKey, $fname );
3316                                         },
3317                                         $fname
3318                                 );
3319                         } else {
3320                                 $this->unlock( $lockKey, $fname );
3321                         }
3322                 } );
3323
3324                 $this->commit( $fname, self::FLUSHING_INTERNAL );
3325
3326                 return $unlocker;
3327         }
3328
3329         public function namedLocksEnqueue() {
3330                 return false;
3331         }
3332
3333         public function tableLocksHaveTransactionScope() {
3334                 return true;
3335         }
3336
3337         final public function lockTables( array $read, array $write, $method ) {
3338                 if ( $this->writesOrCallbacksPending() ) {
3339                         throw new DBUnexpectedError( $this, "Transaction writes or callbacks still pending." );
3340                 }
3341
3342                 if ( $this->tableLocksHaveTransactionScope() ) {
3343                         $this->startAtomic( $method );
3344                 }
3345
3346                 return $this->doLockTables( $read, $write, $method );
3347         }
3348
3349         protected function doLockTables( array $read, array $write, $method ) {
3350                 return true;
3351         }
3352
3353         final public function unlockTables( $method ) {
3354                 if ( $this->tableLocksHaveTransactionScope() ) {
3355                         $this->endAtomic( $method );
3356
3357                         return true; // locks released on COMMIT/ROLLBACK
3358                 }
3359
3360                 return $this->doUnlockTables( $method );
3361         }
3362
3363         protected function doUnlockTables( $method ) {
3364                 return true;
3365         }
3366
3367         /**
3368          * Delete a table
3369          * @param string $tableName
3370          * @param string $fName
3371          * @return bool|ResultWrapper
3372          * @since 1.18
3373          */
3374         public function dropTable( $tableName, $fName = __METHOD__ ) {
3375                 if ( !$this->tableExists( $tableName, $fName ) ) {
3376                         return false;
3377                 }
3378                 $sql = "DROP TABLE " . $this->tableName( $tableName ) . " CASCADE";
3379
3380                 return $this->query( $sql, $fName );
3381         }
3382
3383         public function getInfinity() {
3384                 return 'infinity';
3385         }
3386
3387         public function encodeExpiry( $expiry ) {
3388                 return ( $expiry == '' || $expiry == 'infinity' || $expiry == $this->getInfinity() )
3389                         ? $this->getInfinity()
3390                         : $this->timestamp( $expiry );
3391         }
3392
3393         public function decodeExpiry( $expiry, $format = TS_MW ) {
3394                 if ( $expiry == '' || $expiry == 'infinity' || $expiry == $this->getInfinity() ) {
3395                         return 'infinity';
3396                 }
3397
3398                 return ConvertibleTimestamp::convert( $format, $expiry );
3399         }
3400
3401         public function setBigSelects( $value = true ) {
3402                 // no-op
3403         }
3404
3405         public function isReadOnly() {
3406                 return ( $this->getReadOnlyReason() !== false );
3407         }
3408
3409         /**
3410          * @return string|bool Reason this DB is read-only or false if it is not
3411          */
3412         protected function getReadOnlyReason() {
3413                 $reason = $this->getLBInfo( 'readOnlyReason' );
3414
3415                 return is_string( $reason ) ? $reason : false;
3416         }
3417
3418         public function setTableAliases( array $aliases ) {
3419                 $this->tableAliases = $aliases;
3420         }
3421
3422         /**
3423          * @return bool Whether a DB user is required to access the DB
3424          * @since 1.28
3425          */
3426         protected function requiresDatabaseUser() {
3427                 return true;
3428         }
3429
3430         /**
3431          * Get the underlying binding handle, mConn
3432          *
3433          * Makes sure that mConn is set (disconnects and ping() failure can unset it).
3434          * This catches broken callers than catch and ignore disconnection exceptions.
3435          * Unlike checking isOpen(), this is safe to call inside of open().
3436          *
3437          * @return resource|object
3438          * @throws DBUnexpectedError
3439          * @since 1.26
3440          */
3441         protected function getBindingHandle() {
3442                 if ( !$this->mConn ) {
3443                         throw new DBUnexpectedError(
3444                                 $this,
3445                                 'DB connection was already closed or the connection dropped.'
3446                         );
3447                 }
3448
3449                 return $this->mConn;
3450         }
3451
3452         /**
3453          * @since 1.19
3454          * @return string
3455          */
3456         public function __toString() {
3457                 return (string)$this->mConn;
3458         }
3459
3460         /**
3461          * Make sure that copies do not share the same client binding handle
3462          * @throws DBConnectionError
3463          */
3464         public function __clone() {
3465                 $this->connLogger->warning(
3466                         "Cloning " . static::class . " is not recomended; forking connection:\n" .
3467                         ( new RuntimeException() )->getTraceAsString()
3468                 );
3469
3470                 if ( $this->isOpen() ) {
3471                         // Open a new connection resource without messing with the old one
3472                         $this->mOpened = false;
3473                         $this->mConn = false;
3474                         $this->mTrxEndCallbacks = []; // don't copy
3475                         $this->handleSessionLoss(); // no trx or locks anymore
3476                         $this->open( $this->mServer, $this->mUser, $this->mPassword, $this->mDBname );
3477                         $this->lastPing = microtime( true );
3478                 }
3479         }
3480
3481         /**
3482          * Called by serialize. Throw an exception when DB connection is serialized.
3483          * This causes problems on some database engines because the connection is
3484          * not restored on unserialize.
3485          */
3486         public function __sleep() {
3487                 throw new RuntimeException( 'Database serialization may cause problems, since ' .
3488                         'the connection is not restored on wakeup.' );
3489         }
3490
3491         /**
3492          * Run a few simple sanity checks and close dangling connections
3493          */
3494         public function __destruct() {
3495                 if ( $this->mTrxLevel && $this->mTrxDoneWrites ) {
3496                         trigger_error( "Uncommitted DB writes (transaction from {$this->mTrxFname})." );
3497                 }
3498
3499                 $danglingWriters = $this->pendingWriteAndCallbackCallers();
3500                 if ( $danglingWriters ) {
3501                         $fnames = implode( ', ', $danglingWriters );
3502                         trigger_error( "DB transaction writes or callbacks still pending ($fnames)." );
3503                 }
3504
3505                 if ( $this->mConn ) {
3506                         // Avoid connection leaks for sanity. Normally, resources close at script completion.
3507                         // The connection might already be closed in zend/hhvm by now, so suppress warnings.
3508                         \MediaWiki\suppressWarnings();
3509                         $this->closeConnection();
3510                         \MediaWiki\restoreWarnings();
3511                         $this->mConn = false;
3512                         $this->mOpened = false;
3513                 }
3514         }
3515 }
3516
3517 class_alias( Database::class, 'DatabaseBase' ); // b/c for old name
3518 class_alias( Database::class, 'Database' ); // b/c global alias