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 databasesAreIndependent() {
1709                 return false;
1710         }
1711
1712         public function selectDB( $db ) {
1713                 # Stub. Shouldn't cause serious problems if it's not overridden, but
1714                 # if your database engine supports a concept similar to MySQL's
1715                 # databases you may as well.
1716                 $this->mDBname = $db;
1717
1718                 return true;
1719         }
1720
1721         public function getDBname() {
1722                 return $this->mDBname;
1723         }
1724
1725         public function getServer() {
1726                 return $this->mServer;
1727         }
1728
1729         public function tableName( $name, $format = 'quoted' ) {
1730                 # Skip the entire process when we have a string quoted on both ends.
1731                 # Note that we check the end so that we will still quote any use of
1732                 # use of `database`.table. But won't break things if someone wants
1733                 # to query a database table with a dot in the name.
1734                 if ( $this->isQuotedIdentifier( $name ) ) {
1735                         return $name;
1736                 }
1737
1738                 # Lets test for any bits of text that should never show up in a table
1739                 # name. Basically anything like JOIN or ON which are actually part of
1740                 # SQL queries, but may end up inside of the table value to combine
1741                 # sql. Such as how the API is doing.
1742                 # Note that we use a whitespace test rather than a \b test to avoid
1743                 # any remote case where a word like on may be inside of a table name
1744                 # surrounded by symbols which may be considered word breaks.
1745                 if ( preg_match( '/(^|\s)(DISTINCT|JOIN|ON|AS)(\s|$)/i', $name ) !== 0 ) {
1746                         return $name;
1747                 }
1748
1749                 # Split database and table into proper variables.
1750                 # We reverse the explode so that database.table and table both output
1751                 # the correct table.
1752                 $dbDetails = explode( '.', $name, 3 );
1753                 if ( count( $dbDetails ) == 3 ) {
1754                         list( $database, $schema, $table ) = $dbDetails;
1755                         # We don't want any prefix added in this case
1756                         $prefix = '';
1757                 } elseif ( count( $dbDetails ) == 2 ) {
1758                         list( $database, $table ) = $dbDetails;
1759                         # We don't want any prefix added in this case
1760                         $prefix = '';
1761                         # In dbs that support it, $database may actually be the schema
1762                         # but that doesn't affect any of the functionality here
1763                         $schema = '';
1764                 } else {
1765                         list( $table ) = $dbDetails;
1766                         if ( isset( $this->tableAliases[$table] ) ) {
1767                                 $database = $this->tableAliases[$table]['dbname'];
1768                                 $schema = is_string( $this->tableAliases[$table]['schema'] )
1769                                         ? $this->tableAliases[$table]['schema']
1770                                         : $this->mSchema;
1771                                 $prefix = is_string( $this->tableAliases[$table]['prefix'] )
1772                                         ? $this->tableAliases[$table]['prefix']
1773                                         : $this->mTablePrefix;
1774                         } else {
1775                                 $database = '';
1776                                 $schema = $this->mSchema; # Default schema
1777                                 $prefix = $this->mTablePrefix; # Default prefix
1778                         }
1779                 }
1780
1781                 # Quote $table and apply the prefix if not quoted.
1782                 # $tableName might be empty if this is called from Database::replaceVars()
1783                 $tableName = "{$prefix}{$table}";
1784                 if ( $format === 'quoted'
1785                         && !$this->isQuotedIdentifier( $tableName )
1786                         && $tableName !== ''
1787                 ) {
1788                         $tableName = $this->addIdentifierQuotes( $tableName );
1789                 }
1790
1791                 # Quote $schema and $database and merge them with the table name if needed
1792                 $tableName = $this->prependDatabaseOrSchema( $schema, $tableName, $format );
1793                 $tableName = $this->prependDatabaseOrSchema( $database, $tableName, $format );
1794
1795                 return $tableName;
1796         }
1797
1798         /**
1799          * @param string|null $namespace Database or schema
1800          * @param string $relation Name of table, view, sequence, etc...
1801          * @param string $format One of (raw, quoted)
1802          * @return string Relation name with quoted and merged $namespace as needed
1803          */
1804         private function prependDatabaseOrSchema( $namespace, $relation, $format ) {
1805                 if ( strlen( $namespace ) ) {
1806                         if ( $format === 'quoted' && !$this->isQuotedIdentifier( $namespace ) ) {
1807                                 $namespace = $this->addIdentifierQuotes( $namespace );
1808                         }
1809                         $relation = $namespace . '.' . $relation;
1810                 }
1811
1812                 return $relation;
1813         }
1814
1815         public function tableNames() {
1816                 $inArray = func_get_args();
1817                 $retVal = [];
1818
1819                 foreach ( $inArray as $name ) {
1820                         $retVal[$name] = $this->tableName( $name );
1821                 }
1822
1823                 return $retVal;
1824         }
1825
1826         public function tableNamesN() {
1827                 $inArray = func_get_args();
1828                 $retVal = [];
1829
1830                 foreach ( $inArray as $name ) {
1831                         $retVal[] = $this->tableName( $name );
1832                 }
1833
1834                 return $retVal;
1835         }
1836
1837         /**
1838          * Get an aliased table name
1839          * e.g. tableName AS newTableName
1840          *
1841          * @param string $name Table name, see tableName()
1842          * @param string|bool $alias Alias (optional)
1843          * @return string SQL name for aliased table. Will not alias a table to its own name
1844          */
1845         protected function tableNameWithAlias( $name, $alias = false ) {
1846                 if ( !$alias || $alias == $name ) {
1847                         return $this->tableName( $name );
1848                 } else {
1849                         return $this->tableName( $name ) . ' ' . $this->addIdentifierQuotes( $alias );
1850                 }
1851         }
1852
1853         /**
1854          * Gets an array of aliased table names
1855          *
1856          * @param array $tables [ [alias] => table ]
1857          * @return string[] See tableNameWithAlias()
1858          */
1859         protected function tableNamesWithAlias( $tables ) {
1860                 $retval = [];
1861                 foreach ( $tables as $alias => $table ) {
1862                         if ( is_numeric( $alias ) ) {
1863                                 $alias = $table;
1864                         }
1865                         $retval[] = $this->tableNameWithAlias( $table, $alias );
1866                 }
1867
1868                 return $retval;
1869         }
1870
1871         /**
1872          * Get an aliased field name
1873          * e.g. fieldName AS newFieldName
1874          *
1875          * @param string $name Field name
1876          * @param string|bool $alias Alias (optional)
1877          * @return string SQL name for aliased field. Will not alias a field to its own name
1878          */
1879         protected function fieldNameWithAlias( $name, $alias = false ) {
1880                 if ( !$alias || (string)$alias === (string)$name ) {
1881                         return $name;
1882                 } else {
1883                         return $name . ' AS ' . $this->addIdentifierQuotes( $alias ); // PostgreSQL needs AS
1884                 }
1885         }
1886
1887         /**
1888          * Gets an array of aliased field names
1889          *
1890          * @param array $fields [ [alias] => field ]
1891          * @return string[] See fieldNameWithAlias()
1892          */
1893         protected function fieldNamesWithAlias( $fields ) {
1894                 $retval = [];
1895                 foreach ( $fields as $alias => $field ) {
1896                         if ( is_numeric( $alias ) ) {
1897                                 $alias = $field;
1898                         }
1899                         $retval[] = $this->fieldNameWithAlias( $field, $alias );
1900                 }
1901
1902                 return $retval;
1903         }
1904
1905         /**
1906          * Get the aliased table name clause for a FROM clause
1907          * which might have a JOIN and/or USE INDEX or IGNORE INDEX clause
1908          *
1909          * @param array $tables ( [alias] => table )
1910          * @param array $use_index Same as for select()
1911          * @param array $ignore_index Same as for select()
1912          * @param array $join_conds Same as for select()
1913          * @return string
1914          */
1915         protected function tableNamesWithIndexClauseOrJOIN(
1916                 $tables, $use_index = [], $ignore_index = [], $join_conds = []
1917         ) {
1918                 $ret = [];
1919                 $retJOIN = [];
1920                 $use_index = (array)$use_index;
1921                 $ignore_index = (array)$ignore_index;
1922                 $join_conds = (array)$join_conds;
1923
1924                 foreach ( $tables as $alias => $table ) {
1925                         if ( !is_string( $alias ) ) {
1926                                 // No alias? Set it equal to the table name
1927                                 $alias = $table;
1928                         }
1929                         // Is there a JOIN clause for this table?
1930                         if ( isset( $join_conds[$alias] ) ) {
1931                                 list( $joinType, $conds ) = $join_conds[$alias];
1932                                 $tableClause = $joinType;
1933                                 $tableClause .= ' ' . $this->tableNameWithAlias( $table, $alias );
1934                                 if ( isset( $use_index[$alias] ) ) { // has USE INDEX?
1935                                         $use = $this->useIndexClause( implode( ',', (array)$use_index[$alias] ) );
1936                                         if ( $use != '' ) {
1937                                                 $tableClause .= ' ' . $use;
1938                                         }
1939                                 }
1940                                 if ( isset( $ignore_index[$alias] ) ) { // has IGNORE INDEX?
1941                                         $ignore = $this->ignoreIndexClause(
1942                                                 implode( ',', (array)$ignore_index[$alias] ) );
1943                                         if ( $ignore != '' ) {
1944                                                 $tableClause .= ' ' . $ignore;
1945                                         }
1946                                 }
1947                                 $on = $this->makeList( (array)$conds, self::LIST_AND );
1948                                 if ( $on != '' ) {
1949                                         $tableClause .= ' ON (' . $on . ')';
1950                                 }
1951
1952                                 $retJOIN[] = $tableClause;
1953                         } elseif ( isset( $use_index[$alias] ) ) {
1954                                 // Is there an INDEX clause for this table?
1955                                 $tableClause = $this->tableNameWithAlias( $table, $alias );
1956                                 $tableClause .= ' ' . $this->useIndexClause(
1957                                                 implode( ',', (array)$use_index[$alias] )
1958                                         );
1959
1960                                 $ret[] = $tableClause;
1961                         } elseif ( isset( $ignore_index[$alias] ) ) {
1962                                 // Is there an INDEX clause for this table?
1963                                 $tableClause = $this->tableNameWithAlias( $table, $alias );
1964                                 $tableClause .= ' ' . $this->ignoreIndexClause(
1965                                                 implode( ',', (array)$ignore_index[$alias] )
1966                                         );
1967
1968                                 $ret[] = $tableClause;
1969                         } else {
1970                                 $tableClause = $this->tableNameWithAlias( $table, $alias );
1971
1972                                 $ret[] = $tableClause;
1973                         }
1974                 }
1975
1976                 // We can't separate explicit JOIN clauses with ',', use ' ' for those
1977                 $implicitJoins = !empty( $ret ) ? implode( ',', $ret ) : "";
1978                 $explicitJoins = !empty( $retJOIN ) ? implode( ' ', $retJOIN ) : "";
1979
1980                 // Compile our final table clause
1981                 return implode( ' ', [ $implicitJoins, $explicitJoins ] );
1982         }
1983
1984         /**
1985          * Allows for index remapping in queries where this is not consistent across DBMS
1986          *
1987          * @param string $index
1988          * @return string
1989          */
1990         protected function indexName( $index ) {
1991                 return $index;
1992         }
1993
1994         public function addQuotes( $s ) {
1995                 if ( $s instanceof Blob ) {
1996                         $s = $s->fetch();
1997                 }
1998                 if ( $s === null ) {
1999                         return 'NULL';
2000                 } elseif ( is_bool( $s ) ) {
2001                         return (int)$s;
2002                 } else {
2003                         # This will also quote numeric values. This should be harmless,
2004                         # and protects against weird problems that occur when they really
2005                         # _are_ strings such as article titles and string->number->string
2006                         # conversion is not 1:1.
2007                         return "'" . $this->strencode( $s ) . "'";
2008                 }
2009         }
2010
2011         /**
2012          * Quotes an identifier using `backticks` or "double quotes" depending on the database type.
2013          * MySQL uses `backticks` while basically everything else uses double quotes.
2014          * Since MySQL is the odd one out here the double quotes are our generic
2015          * and we implement backticks in DatabaseMysql.
2016          *
2017          * @param string $s
2018          * @return string
2019          */
2020         public function addIdentifierQuotes( $s ) {
2021                 return '"' . str_replace( '"', '""', $s ) . '"';
2022         }
2023
2024         /**
2025          * Returns if the given identifier looks quoted or not according to
2026          * the database convention for quoting identifiers .
2027          *
2028          * @note Do not use this to determine if untrusted input is safe.
2029          *   A malicious user can trick this function.
2030          * @param string $name
2031          * @return bool
2032          */
2033         public function isQuotedIdentifier( $name ) {
2034                 return $name[0] == '"' && substr( $name, -1, 1 ) == '"';
2035         }
2036
2037         /**
2038          * @param string $s
2039          * @return string
2040          */
2041         protected function escapeLikeInternal( $s, $escapeChar = '`' ) {
2042                 return str_replace( [ $escapeChar, '%', '_' ],
2043                         [ "{$escapeChar}{$escapeChar}", "{$escapeChar}%", "{$escapeChar}_" ],
2044                         $s );
2045         }
2046
2047         public function buildLike() {
2048                 $params = func_get_args();
2049
2050                 if ( count( $params ) > 0 && is_array( $params[0] ) ) {
2051                         $params = $params[0];
2052                 }
2053
2054                 $s = '';
2055
2056                 // We use ` instead of \ as the default LIKE escape character, since addQuotes()
2057                 // may escape backslashes, creating problems of double escaping. The `
2058                 // character has good cross-DBMS compatibility, avoiding special operators
2059                 // in MS SQL like ^ and %
2060                 $escapeChar = '`';
2061
2062                 foreach ( $params as $value ) {
2063                         if ( $value instanceof LikeMatch ) {
2064                                 $s .= $value->toString();
2065                         } else {
2066                                 $s .= $this->escapeLikeInternal( $value, $escapeChar );
2067                         }
2068                 }
2069
2070                 return ' LIKE ' . $this->addQuotes( $s ) . ' ESCAPE ' . $this->addQuotes( $escapeChar ) . ' ';
2071         }
2072
2073         public function anyChar() {
2074                 return new LikeMatch( '_' );
2075         }
2076
2077         public function anyString() {
2078                 return new LikeMatch( '%' );
2079         }
2080
2081         public function nextSequenceValue( $seqName ) {
2082                 return null;
2083         }
2084
2085         /**
2086          * USE INDEX clause. Unlikely to be useful for anything but MySQL. This
2087          * is only needed because a) MySQL must be as efficient as possible due to
2088          * its use on Wikipedia, and b) MySQL 4.0 is kind of dumb sometimes about
2089          * which index to pick. Anyway, other databases might have different
2090          * indexes on a given table. So don't bother overriding this unless you're
2091          * MySQL.
2092          * @param string $index
2093          * @return string
2094          */
2095         public function useIndexClause( $index ) {
2096                 return '';
2097         }
2098
2099         /**
2100          * IGNORE INDEX clause. Unlikely to be useful for anything but MySQL. This
2101          * is only needed because a) MySQL must be as efficient as possible due to
2102          * its use on Wikipedia, and b) MySQL 4.0 is kind of dumb sometimes about
2103          * which index to pick. Anyway, other databases might have different
2104          * indexes on a given table. So don't bother overriding this unless you're
2105          * MySQL.
2106          * @param string $index
2107          * @return string
2108          */
2109         public function ignoreIndexClause( $index ) {
2110                 return '';
2111         }
2112
2113         public function replace( $table, $uniqueIndexes, $rows, $fname = __METHOD__ ) {
2114                 $quotedTable = $this->tableName( $table );
2115
2116                 if ( count( $rows ) == 0 ) {
2117                         return;
2118                 }
2119
2120                 # Single row case
2121                 if ( !is_array( reset( $rows ) ) ) {
2122                         $rows = [ $rows ];
2123                 }
2124
2125                 // @FXIME: this is not atomic, but a trx would break affectedRows()
2126                 foreach ( $rows as $row ) {
2127                         # Delete rows which collide
2128                         if ( $uniqueIndexes ) {
2129                                 $sql = "DELETE FROM $quotedTable WHERE ";
2130                                 $first = true;
2131                                 foreach ( $uniqueIndexes as $index ) {
2132                                         if ( $first ) {
2133                                                 $first = false;
2134                                                 $sql .= '( ';
2135                                         } else {
2136                                                 $sql .= ' ) OR ( ';
2137                                         }
2138                                         if ( is_array( $index ) ) {
2139                                                 $first2 = true;
2140                                                 foreach ( $index as $col ) {
2141                                                         if ( $first2 ) {
2142                                                                 $first2 = false;
2143                                                         } else {
2144                                                                 $sql .= ' AND ';
2145                                                         }
2146                                                         $sql .= $col . '=' . $this->addQuotes( $row[$col] );
2147                                                 }
2148                                         } else {
2149                                                 $sql .= $index . '=' . $this->addQuotes( $row[$index] );
2150                                         }
2151                                 }
2152                                 $sql .= ' )';
2153                                 $this->query( $sql, $fname );
2154                         }
2155
2156                         # Now insert the row
2157                         $this->insert( $table, $row, $fname );
2158                 }
2159         }
2160
2161         /**
2162          * REPLACE query wrapper for MySQL and SQLite, which have a native REPLACE
2163          * statement.
2164          *
2165          * @param string $table Table name
2166          * @param array|string $rows Row(s) to insert
2167          * @param string $fname Caller function name
2168          *
2169          * @return ResultWrapper
2170          */
2171         protected function nativeReplace( $table, $rows, $fname ) {
2172                 $table = $this->tableName( $table );
2173
2174                 # Single row case
2175                 if ( !is_array( reset( $rows ) ) ) {
2176                         $rows = [ $rows ];
2177                 }
2178
2179                 $sql = "REPLACE INTO $table (" . implode( ',', array_keys( $rows[0] ) ) . ') VALUES ';
2180                 $first = true;
2181
2182                 foreach ( $rows as $row ) {
2183                         if ( $first ) {
2184                                 $first = false;
2185                         } else {
2186                                 $sql .= ',';
2187                         }
2188
2189                         $sql .= '(' . $this->makeList( $row ) . ')';
2190                 }
2191
2192                 return $this->query( $sql, $fname );
2193         }
2194
2195         public function upsert( $table, array $rows, array $uniqueIndexes, array $set,
2196                 $fname = __METHOD__
2197         ) {
2198                 if ( !count( $rows ) ) {
2199                         return true; // nothing to do
2200                 }
2201
2202                 if ( !is_array( reset( $rows ) ) ) {
2203                         $rows = [ $rows ];
2204                 }
2205
2206                 if ( count( $uniqueIndexes ) ) {
2207                         $clauses = []; // list WHERE clauses that each identify a single row
2208                         foreach ( $rows as $row ) {
2209                                 foreach ( $uniqueIndexes as $index ) {
2210                                         $index = is_array( $index ) ? $index : [ $index ]; // columns
2211                                         $rowKey = []; // unique key to this row
2212                                         foreach ( $index as $column ) {
2213                                                 $rowKey[$column] = $row[$column];
2214                                         }
2215                                         $clauses[] = $this->makeList( $rowKey, self::LIST_AND );
2216                                 }
2217                         }
2218                         $where = [ $this->makeList( $clauses, self::LIST_OR ) ];
2219                 } else {
2220                         $where = false;
2221                 }
2222
2223                 $useTrx = !$this->mTrxLevel;
2224                 if ( $useTrx ) {
2225                         $this->begin( $fname, self::TRANSACTION_INTERNAL );
2226                 }
2227                 try {
2228                         # Update any existing conflicting row(s)
2229                         if ( $where !== false ) {
2230                                 $ok = $this->update( $table, $set, $where, $fname );
2231                         } else {
2232                                 $ok = true;
2233                         }
2234                         # Now insert any non-conflicting row(s)
2235                         $ok = $this->insert( $table, $rows, $fname, [ 'IGNORE' ] ) && $ok;
2236                 } catch ( Exception $e ) {
2237                         if ( $useTrx ) {
2238                                 $this->rollback( $fname, self::FLUSHING_INTERNAL );
2239                         }
2240                         throw $e;
2241                 }
2242                 if ( $useTrx ) {
2243                         $this->commit( $fname, self::FLUSHING_INTERNAL );
2244                 }
2245
2246                 return $ok;
2247         }
2248
2249         public function deleteJoin( $delTable, $joinTable, $delVar, $joinVar, $conds,
2250                 $fname = __METHOD__
2251         ) {
2252                 if ( !$conds ) {
2253                         throw new DBUnexpectedError( $this, __METHOD__ . ' called with empty $conds' );
2254                 }
2255
2256                 $delTable = $this->tableName( $delTable );
2257                 $joinTable = $this->tableName( $joinTable );
2258                 $sql = "DELETE FROM $delTable WHERE $delVar IN (SELECT $joinVar FROM $joinTable ";
2259                 if ( $conds != '*' ) {
2260                         $sql .= 'WHERE ' . $this->makeList( $conds, self::LIST_AND );
2261                 }
2262                 $sql .= ')';
2263
2264                 $this->query( $sql, $fname );
2265         }
2266
2267         public function textFieldSize( $table, $field ) {
2268                 $table = $this->tableName( $table );
2269                 $sql = "SHOW COLUMNS FROM $table LIKE \"$field\";";
2270                 $res = $this->query( $sql, __METHOD__ );
2271                 $row = $this->fetchObject( $res );
2272
2273                 $m = [];
2274
2275                 if ( preg_match( '/\((.*)\)/', $row->Type, $m ) ) {
2276                         $size = $m[1];
2277                 } else {
2278                         $size = -1;
2279                 }
2280
2281                 return $size;
2282         }
2283
2284         public function delete( $table, $conds, $fname = __METHOD__ ) {
2285                 if ( !$conds ) {
2286                         throw new DBUnexpectedError( $this, __METHOD__ . ' called with no conditions' );
2287                 }
2288
2289                 $table = $this->tableName( $table );
2290                 $sql = "DELETE FROM $table";
2291
2292                 if ( $conds != '*' ) {
2293                         if ( is_array( $conds ) ) {
2294                                 $conds = $this->makeList( $conds, self::LIST_AND );
2295                         }
2296                         $sql .= ' WHERE ' . $conds;
2297                 }
2298
2299                 return $this->query( $sql, $fname );
2300         }
2301
2302         public function insertSelect(
2303                 $destTable, $srcTable, $varMap, $conds,
2304                 $fname = __METHOD__, $insertOptions = [], $selectOptions = []
2305         ) {
2306                 if ( $this->cliMode ) {
2307                         // For massive migrations with downtime, we don't want to select everything
2308                         // into memory and OOM, so do all this native on the server side if possible.
2309                         return $this->nativeInsertSelect(
2310                                 $destTable,
2311                                 $srcTable,
2312                                 $varMap,
2313                                 $conds,
2314                                 $fname,
2315                                 $insertOptions,
2316                                 $selectOptions
2317                         );
2318                 }
2319
2320                 // For web requests, do a locking SELECT and then INSERT. This puts the SELECT burden
2321                 // on only the master (without needing row-based-replication). It also makes it easy to
2322                 // know how big the INSERT is going to be.
2323                 $fields = [];
2324                 foreach ( $varMap as $dstColumn => $sourceColumnOrSql ) {
2325                         $fields[] = $this->fieldNameWithAlias( $sourceColumnOrSql, $dstColumn );
2326                 }
2327                 $selectOptions[] = 'FOR UPDATE';
2328                 $res = $this->select( $srcTable, implode( ',', $fields ), $conds, $fname, $selectOptions );
2329                 if ( !$res ) {
2330                         return false;
2331                 }
2332
2333                 $rows = [];
2334                 foreach ( $res as $row ) {
2335                         $rows[] = (array)$row;
2336                 }
2337
2338                 return $this->insert( $destTable, $rows, $fname, $insertOptions );
2339         }
2340
2341         protected function nativeInsertSelect( $destTable, $srcTable, $varMap, $conds,
2342                 $fname = __METHOD__,
2343                 $insertOptions = [], $selectOptions = []
2344         ) {
2345                 $destTable = $this->tableName( $destTable );
2346
2347                 if ( !is_array( $insertOptions ) ) {
2348                         $insertOptions = [ $insertOptions ];
2349                 }
2350
2351                 $insertOptions = $this->makeInsertOptions( $insertOptions );
2352
2353                 if ( !is_array( $selectOptions ) ) {
2354                         $selectOptions = [ $selectOptions ];
2355                 }
2356
2357                 list( $startOpts, $useIndex, $tailOpts, $ignoreIndex ) = $this->makeSelectOptions(
2358                         $selectOptions );
2359
2360                 if ( is_array( $srcTable ) ) {
2361                         $srcTable = implode( ',', array_map( [ $this, 'tableName' ], $srcTable ) );
2362                 } else {
2363                         $srcTable = $this->tableName( $srcTable );
2364                 }
2365
2366                 $sql = "INSERT $insertOptions" .
2367                         " INTO $destTable (" . implode( ',', array_keys( $varMap ) ) . ')' .
2368                         " SELECT $startOpts " . implode( ',', $varMap ) .
2369                         " FROM $srcTable $useIndex $ignoreIndex ";
2370
2371                 if ( $conds != '*' ) {
2372                         if ( is_array( $conds ) ) {
2373                                 $conds = $this->makeList( $conds, self::LIST_AND );
2374                         }
2375                         $sql .= " WHERE $conds";
2376                 }
2377
2378                 $sql .= " $tailOpts";
2379
2380                 return $this->query( $sql, $fname );
2381         }
2382
2383         /**
2384          * Construct a LIMIT query with optional offset. This is used for query
2385          * pages. The SQL should be adjusted so that only the first $limit rows
2386          * are returned. If $offset is provided as well, then the first $offset
2387          * rows should be discarded, and the next $limit rows should be returned.
2388          * If the result of the query is not ordered, then the rows to be returned
2389          * are theoretically arbitrary.
2390          *
2391          * $sql is expected to be a SELECT, if that makes a difference.
2392          *
2393          * The version provided by default works in MySQL and SQLite. It will very
2394          * likely need to be overridden for most other DBMSes.
2395          *
2396          * @param string $sql SQL query we will append the limit too
2397          * @param int $limit The SQL limit
2398          * @param int|bool $offset The SQL offset (default false)
2399          * @throws DBUnexpectedError
2400          * @return string
2401          */
2402         public function limitResult( $sql, $limit, $offset = false ) {
2403                 if ( !is_numeric( $limit ) ) {
2404                         throw new DBUnexpectedError( $this,
2405                                 "Invalid non-numeric limit passed to limitResult()\n" );
2406                 }
2407
2408                 return "$sql LIMIT "
2409                 . ( ( is_numeric( $offset ) && $offset != 0 ) ? "{$offset}," : "" )
2410                 . "{$limit} ";
2411         }
2412
2413         public function unionSupportsOrderAndLimit() {
2414                 return true; // True for almost every DB supported
2415         }
2416
2417         public function unionQueries( $sqls, $all ) {
2418                 $glue = $all ? ') UNION ALL (' : ') UNION (';
2419
2420                 return '(' . implode( $glue, $sqls ) . ')';
2421         }
2422
2423         public function conditional( $cond, $trueVal, $falseVal ) {
2424                 if ( is_array( $cond ) ) {
2425                         $cond = $this->makeList( $cond, self::LIST_AND );
2426                 }
2427
2428                 return " (CASE WHEN $cond THEN $trueVal ELSE $falseVal END) ";
2429         }
2430
2431         public function strreplace( $orig, $old, $new ) {
2432                 return "REPLACE({$orig}, {$old}, {$new})";
2433         }
2434
2435         public function getServerUptime() {
2436                 return 0;
2437         }
2438
2439         public function wasDeadlock() {
2440                 return false;
2441         }
2442
2443         public function wasLockTimeout() {
2444                 return false;
2445         }
2446
2447         public function wasErrorReissuable() {
2448                 return false;
2449         }
2450
2451         public function wasReadOnlyError() {
2452                 return false;
2453         }
2454
2455         /**
2456          * Do not use this method outside of Database/DBError classes
2457          *
2458          * @param integer|string $errno
2459          * @return bool Whether the given query error was a connection drop
2460          */
2461         public function wasConnectionError( $errno ) {
2462                 return false;
2463         }
2464
2465         public function deadlockLoop() {
2466                 $args = func_get_args();
2467                 $function = array_shift( $args );
2468                 $tries = self::DEADLOCK_TRIES;
2469
2470                 $this->begin( __METHOD__ );
2471
2472                 $retVal = null;
2473                 /** @var Exception $e */
2474                 $e = null;
2475                 do {
2476                         try {
2477                                 $retVal = call_user_func_array( $function, $args );
2478                                 break;
2479                         } catch ( DBQueryError $e ) {
2480                                 if ( $this->wasDeadlock() ) {
2481                                         // Retry after a randomized delay
2482                                         usleep( mt_rand( self::DEADLOCK_DELAY_MIN, self::DEADLOCK_DELAY_MAX ) );
2483                                 } else {
2484                                         // Throw the error back up
2485                                         throw $e;
2486                                 }
2487                         }
2488                 } while ( --$tries > 0 );
2489
2490                 if ( $tries <= 0 ) {
2491                         // Too many deadlocks; give up
2492                         $this->rollback( __METHOD__ );
2493                         throw $e;
2494                 } else {
2495                         $this->commit( __METHOD__ );
2496
2497                         return $retVal;
2498                 }
2499         }
2500
2501         public function masterPosWait( DBMasterPos $pos, $timeout ) {
2502                 # Real waits are implemented in the subclass.
2503                 return 0;
2504         }
2505
2506         public function getReplicaPos() {
2507                 # Stub
2508                 return false;
2509         }
2510
2511         public function getMasterPos() {
2512                 # Stub
2513                 return false;
2514         }
2515
2516         public function serverIsReadOnly() {
2517                 return false;
2518         }
2519
2520         final public function onTransactionResolution( callable $callback, $fname = __METHOD__ ) {
2521                 if ( !$this->mTrxLevel ) {
2522                         throw new DBUnexpectedError( $this, "No transaction is active." );
2523                 }
2524                 $this->mTrxEndCallbacks[] = [ $callback, $fname ];
2525         }
2526
2527         final public function onTransactionIdle( callable $callback, $fname = __METHOD__ ) {
2528                 $this->mTrxIdleCallbacks[] = [ $callback, $fname ];
2529                 if ( !$this->mTrxLevel ) {
2530                         $this->runOnTransactionIdleCallbacks( self::TRIGGER_IDLE );
2531                 }
2532         }
2533
2534         final public function onTransactionPreCommitOrIdle( callable $callback, $fname = __METHOD__ ) {
2535                 if ( $this->mTrxLevel ) {
2536                         $this->mTrxPreCommitCallbacks[] = [ $callback, $fname ];
2537                 } else {
2538                         // If no transaction is active, then make one for this callback
2539                         $this->startAtomic( __METHOD__ );
2540                         try {
2541                                 call_user_func( $callback );
2542                                 $this->endAtomic( __METHOD__ );
2543                         } catch ( Exception $e ) {
2544                                 $this->rollback( __METHOD__, self::FLUSHING_INTERNAL );
2545                                 throw $e;
2546                         }
2547                 }
2548         }
2549
2550         final public function setTransactionListener( $name, callable $callback = null ) {
2551                 if ( $callback ) {
2552                         $this->mTrxRecurringCallbacks[$name] = $callback;
2553                 } else {
2554                         unset( $this->mTrxRecurringCallbacks[$name] );
2555                 }
2556         }
2557
2558         /**
2559          * Whether to disable running of post-COMMIT/ROLLBACK callbacks
2560          *
2561          * This method should not be used outside of Database/LoadBalancer
2562          *
2563          * @param bool $suppress
2564          * @since 1.28
2565          */
2566         final public function setTrxEndCallbackSuppression( $suppress ) {
2567                 $this->mTrxEndCallbacksSuppressed = $suppress;
2568         }
2569
2570         /**
2571          * Actually run and consume any "on transaction idle/resolution" callbacks.
2572          *
2573          * This method should not be used outside of Database/LoadBalancer
2574          *
2575          * @param integer $trigger IDatabase::TRIGGER_* constant
2576          * @since 1.20
2577          * @throws Exception
2578          */
2579         public function runOnTransactionIdleCallbacks( $trigger ) {
2580                 if ( $this->mTrxEndCallbacksSuppressed ) {
2581                         return;
2582                 }
2583
2584                 $autoTrx = $this->getFlag( self::DBO_TRX ); // automatic begin() enabled?
2585                 /** @var Exception $e */
2586                 $e = null; // first exception
2587                 do { // callbacks may add callbacks :)
2588                         $callbacks = array_merge(
2589                                 $this->mTrxIdleCallbacks,
2590                                 $this->mTrxEndCallbacks // include "transaction resolution" callbacks
2591                         );
2592                         $this->mTrxIdleCallbacks = []; // consumed (and recursion guard)
2593                         $this->mTrxEndCallbacks = []; // consumed (recursion guard)
2594                         foreach ( $callbacks as $callback ) {
2595                                 try {
2596                                         list( $phpCallback ) = $callback;
2597                                         $this->clearFlag( self::DBO_TRX ); // make each query its own transaction
2598                                         call_user_func_array( $phpCallback, [ $trigger ] );
2599                                         if ( $autoTrx ) {
2600                                                 $this->setFlag( self::DBO_TRX ); // restore automatic begin()
2601                                         } else {
2602                                                 $this->clearFlag( self::DBO_TRX ); // restore auto-commit
2603                                         }
2604                                 } catch ( Exception $ex ) {
2605                                         call_user_func( $this->errorLogger, $ex );
2606                                         $e = $e ?: $ex;
2607                                         // Some callbacks may use startAtomic/endAtomic, so make sure
2608                                         // their transactions are ended so other callbacks don't fail
2609                                         if ( $this->trxLevel() ) {
2610                                                 $this->rollback( __METHOD__, self::FLUSHING_INTERNAL );
2611                                         }
2612                                 }
2613                         }
2614                 } while ( count( $this->mTrxIdleCallbacks ) );
2615
2616                 if ( $e instanceof Exception ) {
2617                         throw $e; // re-throw any first exception
2618                 }
2619         }
2620
2621         /**
2622          * Actually run and consume any "on transaction pre-commit" callbacks.
2623          *
2624          * This method should not be used outside of Database/LoadBalancer
2625          *
2626          * @since 1.22
2627          * @throws Exception
2628          */
2629         public function runOnTransactionPreCommitCallbacks() {
2630                 $e = null; // first exception
2631                 do { // callbacks may add callbacks :)
2632                         $callbacks = $this->mTrxPreCommitCallbacks;
2633                         $this->mTrxPreCommitCallbacks = []; // consumed (and recursion guard)
2634                         foreach ( $callbacks as $callback ) {
2635                                 try {
2636                                         list( $phpCallback ) = $callback;
2637                                         call_user_func( $phpCallback );
2638                                 } catch ( Exception $ex ) {
2639                                         call_user_func( $this->errorLogger, $ex );
2640                                         $e = $e ?: $ex;
2641                                 }
2642                         }
2643                 } while ( count( $this->mTrxPreCommitCallbacks ) );
2644
2645                 if ( $e instanceof Exception ) {
2646                         throw $e; // re-throw any first exception
2647                 }
2648         }
2649
2650         /**
2651          * Actually run any "transaction listener" callbacks.
2652          *
2653          * This method should not be used outside of Database/LoadBalancer
2654          *
2655          * @param integer $trigger IDatabase::TRIGGER_* constant
2656          * @throws Exception
2657          * @since 1.20
2658          */
2659         public function runTransactionListenerCallbacks( $trigger ) {
2660                 if ( $this->mTrxEndCallbacksSuppressed ) {
2661                         return;
2662                 }
2663
2664                 /** @var Exception $e */
2665                 $e = null; // first exception
2666
2667                 foreach ( $this->mTrxRecurringCallbacks as $phpCallback ) {
2668                         try {
2669                                 $phpCallback( $trigger, $this );
2670                         } catch ( Exception $ex ) {
2671                                 call_user_func( $this->errorLogger, $ex );
2672                                 $e = $e ?: $ex;
2673                         }
2674                 }
2675
2676                 if ( $e instanceof Exception ) {
2677                         throw $e; // re-throw any first exception
2678                 }
2679         }
2680
2681         final public function startAtomic( $fname = __METHOD__ ) {
2682                 if ( !$this->mTrxLevel ) {
2683                         $this->begin( $fname, self::TRANSACTION_INTERNAL );
2684                         // If DBO_TRX is set, a series of startAtomic/endAtomic pairs will result
2685                         // in all changes being in one transaction to keep requests transactional.
2686                         if ( !$this->getFlag( self::DBO_TRX ) ) {
2687                                 $this->mTrxAutomaticAtomic = true;
2688                         }
2689                 }
2690
2691                 $this->mTrxAtomicLevels[] = $fname;
2692         }
2693
2694         final public function endAtomic( $fname = __METHOD__ ) {
2695                 if ( !$this->mTrxLevel ) {
2696                         throw new DBUnexpectedError( $this, "No atomic transaction is open (got $fname)." );
2697                 }
2698                 if ( !$this->mTrxAtomicLevels ||
2699                         array_pop( $this->mTrxAtomicLevels ) !== $fname
2700                 ) {
2701                         throw new DBUnexpectedError( $this, "Invalid atomic section ended (got $fname)." );
2702                 }
2703
2704                 if ( !$this->mTrxAtomicLevels && $this->mTrxAutomaticAtomic ) {
2705                         $this->commit( $fname, self::FLUSHING_INTERNAL );
2706                 }
2707         }
2708
2709         final public function doAtomicSection( $fname, callable $callback ) {
2710                 $this->startAtomic( $fname );
2711                 try {
2712                         $res = call_user_func_array( $callback, [ $this, $fname ] );
2713                 } catch ( Exception $e ) {
2714                         $this->rollback( $fname, self::FLUSHING_INTERNAL );
2715                         throw $e;
2716                 }
2717                 $this->endAtomic( $fname );
2718
2719                 return $res;
2720         }
2721
2722         final public function begin( $fname = __METHOD__, $mode = self::TRANSACTION_EXPLICIT ) {
2723                 // Protect against mismatched atomic section, transaction nesting, and snapshot loss
2724                 if ( $this->mTrxLevel ) {
2725                         if ( $this->mTrxAtomicLevels ) {
2726                                 $levels = implode( ', ', $this->mTrxAtomicLevels );
2727                                 $msg = "$fname: Got explicit BEGIN while atomic section(s) $levels are open.";
2728                                 throw new DBUnexpectedError( $this, $msg );
2729                         } elseif ( !$this->mTrxAutomatic ) {
2730                                 $msg = "$fname: Explicit transaction already active (from {$this->mTrxFname}).";
2731                                 throw new DBUnexpectedError( $this, $msg );
2732                         } else {
2733                                 // @TODO: make this an exception at some point
2734                                 $msg = "$fname: Implicit transaction already active (from {$this->mTrxFname}).";
2735                                 $this->queryLogger->error( $msg );
2736                                 return; // join the main transaction set
2737                         }
2738                 } elseif ( $this->getFlag( self::DBO_TRX ) && $mode !== self::TRANSACTION_INTERNAL ) {
2739                         // @TODO: make this an exception at some point
2740                         $msg = "$fname: Implicit transaction expected (DBO_TRX set).";
2741                         $this->queryLogger->error( $msg );
2742                         return; // let any writes be in the main transaction
2743                 }
2744
2745                 // Avoid fatals if close() was called
2746                 $this->assertOpen();
2747
2748                 $this->doBegin( $fname );
2749                 $this->mTrxTimestamp = microtime( true );
2750                 $this->mTrxFname = $fname;
2751                 $this->mTrxDoneWrites = false;
2752                 $this->mTrxAutomaticAtomic = false;
2753                 $this->mTrxAtomicLevels = [];
2754                 $this->mTrxShortId = sprintf( '%06x', mt_rand( 0, 0xffffff ) );
2755                 $this->mTrxWriteDuration = 0.0;
2756                 $this->mTrxWriteQueryCount = 0;
2757                 $this->mTrxWriteAdjDuration = 0.0;
2758                 $this->mTrxWriteAdjQueryCount = 0;
2759                 $this->mTrxWriteCallers = [];
2760                 // First SELECT after BEGIN will establish the snapshot in REPEATABLE-READ.
2761                 // Get an estimate of the replica DB lag before then, treating estimate staleness
2762                 // as lag itself just to be safe
2763                 $status = $this->getApproximateLagStatus();
2764                 $this->mTrxReplicaLag = $status['lag'] + ( microtime( true ) - $status['since'] );
2765                 // T147697: make explicitTrxActive() return true until begin() finishes. This way, no
2766                 // caller will think its OK to muck around with the transaction just because startAtomic()
2767                 // has not yet completed (e.g. setting mTrxAtomicLevels).
2768                 $this->mTrxAutomatic = ( $mode === self::TRANSACTION_INTERNAL );
2769         }
2770
2771         /**
2772          * Issues the BEGIN command to the database server.
2773          *
2774          * @see Database::begin()
2775          * @param string $fname
2776          */
2777         protected function doBegin( $fname ) {
2778                 $this->query( 'BEGIN', $fname );
2779                 $this->mTrxLevel = 1;
2780         }
2781
2782         final public function commit( $fname = __METHOD__, $flush = '' ) {
2783                 if ( $this->mTrxLevel && $this->mTrxAtomicLevels ) {
2784                         // There are still atomic sections open. This cannot be ignored
2785                         $levels = implode( ', ', $this->mTrxAtomicLevels );
2786                         throw new DBUnexpectedError(
2787                                 $this,
2788                                 "$fname: Got COMMIT while atomic sections $levels are still open."
2789                         );
2790                 }
2791
2792                 if ( $flush === self::FLUSHING_INTERNAL || $flush === self::FLUSHING_ALL_PEERS ) {
2793                         if ( !$this->mTrxLevel ) {
2794                                 return; // nothing to do
2795                         } elseif ( !$this->mTrxAutomatic ) {
2796                                 throw new DBUnexpectedError(
2797                                         $this,
2798                                         "$fname: Flushing an explicit transaction, getting out of sync."
2799                                 );
2800                         }
2801                 } else {
2802                         if ( !$this->mTrxLevel ) {
2803                                 $this->queryLogger->error(
2804                                         "$fname: No transaction to commit, something got out of sync." );
2805                                 return; // nothing to do
2806                         } elseif ( $this->mTrxAutomatic ) {
2807                                 // @TODO: make this an exception at some point
2808                                 $msg = "$fname: Explicit commit of implicit transaction.";
2809                                 $this->queryLogger->error( $msg );
2810                                 return; // wait for the main transaction set commit round
2811                         }
2812                 }
2813
2814                 // Avoid fatals if close() was called
2815                 $this->assertOpen();
2816
2817                 $this->runOnTransactionPreCommitCallbacks();
2818                 $writeTime = $this->pendingWriteQueryDuration( self::ESTIMATE_DB_APPLY );
2819                 $this->doCommit( $fname );
2820                 if ( $this->mTrxDoneWrites ) {
2821                         $this->mLastWriteTime = microtime( true );
2822                         $this->trxProfiler->transactionWritingOut(
2823                                 $this->mServer, $this->mDBname, $this->mTrxShortId, $writeTime );
2824                 }
2825
2826                 $this->runOnTransactionIdleCallbacks( self::TRIGGER_COMMIT );
2827                 $this->runTransactionListenerCallbacks( self::TRIGGER_COMMIT );
2828         }
2829
2830         /**
2831          * Issues the COMMIT command to the database server.
2832          *
2833          * @see Database::commit()
2834          * @param string $fname
2835          */
2836         protected function doCommit( $fname ) {
2837                 if ( $this->mTrxLevel ) {
2838                         $this->query( 'COMMIT', $fname );
2839                         $this->mTrxLevel = 0;
2840                 }
2841         }
2842
2843         final public function rollback( $fname = __METHOD__, $flush = '' ) {
2844                 if ( $flush === self::FLUSHING_INTERNAL || $flush === self::FLUSHING_ALL_PEERS ) {
2845                         if ( !$this->mTrxLevel ) {
2846                                 return; // nothing to do
2847                         }
2848                 } else {
2849                         if ( !$this->mTrxLevel ) {
2850                                 $this->queryLogger->error(
2851                                         "$fname: No transaction to rollback, something got out of sync." );
2852                                 return; // nothing to do
2853                         } elseif ( $this->getFlag( self::DBO_TRX ) ) {
2854                                 throw new DBUnexpectedError(
2855                                         $this,
2856                                         "$fname: Expected mass rollback of all peer databases (DBO_TRX set)."
2857                                 );
2858                         }
2859                 }
2860
2861                 // Avoid fatals if close() was called
2862                 $this->assertOpen();
2863
2864                 $this->doRollback( $fname );
2865                 $this->mTrxAtomicLevels = [];
2866                 if ( $this->mTrxDoneWrites ) {
2867                         $this->trxProfiler->transactionWritingOut(
2868                                 $this->mServer, $this->mDBname, $this->mTrxShortId );
2869                 }
2870
2871                 $this->mTrxIdleCallbacks = []; // clear
2872                 $this->mTrxPreCommitCallbacks = []; // clear
2873                 $this->runOnTransactionIdleCallbacks( self::TRIGGER_ROLLBACK );
2874                 $this->runTransactionListenerCallbacks( self::TRIGGER_ROLLBACK );
2875         }
2876
2877         /**
2878          * Issues the ROLLBACK command to the database server.
2879          *
2880          * @see Database::rollback()
2881          * @param string $fname
2882          */
2883         protected function doRollback( $fname ) {
2884                 if ( $this->mTrxLevel ) {
2885                         # Disconnects cause rollback anyway, so ignore those errors
2886                         $ignoreErrors = true;
2887                         $this->query( 'ROLLBACK', $fname, $ignoreErrors );
2888                         $this->mTrxLevel = 0;
2889                 }
2890         }
2891
2892         public function flushSnapshot( $fname = __METHOD__ ) {
2893                 if ( $this->writesOrCallbacksPending() || $this->explicitTrxActive() ) {
2894                         // This only flushes transactions to clear snapshots, not to write data
2895                         $fnames = implode( ', ', $this->pendingWriteAndCallbackCallers() );
2896                         throw new DBUnexpectedError(
2897                                 $this,
2898                                 "$fname: Cannot flush snapshot because writes are pending ($fnames)."
2899                         );
2900                 }
2901
2902                 $this->commit( $fname, self::FLUSHING_INTERNAL );
2903         }
2904
2905         public function explicitTrxActive() {
2906                 return $this->mTrxLevel && ( $this->mTrxAtomicLevels || !$this->mTrxAutomatic );
2907         }
2908
2909         public function duplicateTableStructure(
2910                 $oldName, $newName, $temporary = false, $fname = __METHOD__
2911         ) {
2912                 throw new RuntimeException( __METHOD__ . ' is not implemented in descendant class' );
2913         }
2914
2915         public function listTables( $prefix = null, $fname = __METHOD__ ) {
2916                 throw new RuntimeException( __METHOD__ . ' is not implemented in descendant class' );
2917         }
2918
2919         public function listViews( $prefix = null, $fname = __METHOD__ ) {
2920                 throw new RuntimeException( __METHOD__ . ' is not implemented in descendant class' );
2921         }
2922
2923         public function timestamp( $ts = 0 ) {
2924                 $t = new ConvertibleTimestamp( $ts );
2925                 // Let errors bubble up to avoid putting garbage in the DB
2926                 return $t->getTimestamp( TS_MW );
2927         }
2928
2929         public function timestampOrNull( $ts = null ) {
2930                 if ( is_null( $ts ) ) {
2931                         return null;
2932                 } else {
2933                         return $this->timestamp( $ts );
2934                 }
2935         }
2936
2937         /**
2938          * Take the result from a query, and wrap it in a ResultWrapper if
2939          * necessary. Boolean values are passed through as is, to indicate success
2940          * of write queries or failure.
2941          *
2942          * Once upon a time, Database::query() returned a bare MySQL result
2943          * resource, and it was necessary to call this function to convert it to
2944          * a wrapper. Nowadays, raw database objects are never exposed to external
2945          * callers, so this is unnecessary in external code.
2946          *
2947          * @param bool|ResultWrapper|resource|object $result
2948          * @return bool|ResultWrapper
2949          */
2950         protected function resultObject( $result ) {
2951                 if ( !$result ) {
2952                         return false;
2953                 } elseif ( $result instanceof ResultWrapper ) {
2954                         return $result;
2955                 } elseif ( $result === true ) {
2956                         // Successful write query
2957                         return $result;
2958                 } else {
2959                         return new ResultWrapper( $this, $result );
2960                 }
2961         }
2962
2963         public function ping( &$rtt = null ) {
2964                 // Avoid hitting the server if it was hit recently
2965                 if ( $this->isOpen() && ( microtime( true ) - $this->lastPing ) < self::PING_TTL ) {
2966                         if ( !func_num_args() || $this->mRTTEstimate > 0 ) {
2967                                 $rtt = $this->mRTTEstimate;
2968                                 return true; // don't care about $rtt
2969                         }
2970                 }
2971
2972                 // This will reconnect if possible or return false if not
2973                 $this->clearFlag( self::DBO_TRX, self::REMEMBER_PRIOR );
2974                 $ok = ( $this->query( self::PING_QUERY, __METHOD__, true ) !== false );
2975                 $this->restoreFlags( self::RESTORE_PRIOR );
2976
2977                 if ( $ok ) {
2978                         $rtt = $this->mRTTEstimate;
2979                 }
2980
2981                 return $ok;
2982         }
2983
2984         /**
2985          * @return bool
2986          */
2987         protected function reconnect() {
2988                 $this->closeConnection();
2989                 $this->mOpened = false;
2990                 $this->mConn = false;
2991                 try {
2992                         $this->open( $this->mServer, $this->mUser, $this->mPassword, $this->mDBname );
2993                         $this->lastPing = microtime( true );
2994                         $ok = true;
2995                 } catch ( DBConnectionError $e ) {
2996                         $ok = false;
2997                 }
2998
2999                 return $ok;
3000         }
3001
3002         public function getSessionLagStatus() {
3003                 return $this->getTransactionLagStatus() ?: $this->getApproximateLagStatus();
3004         }
3005
3006         /**
3007          * Get the replica DB lag when the current transaction started
3008          *
3009          * This is useful when transactions might use snapshot isolation
3010          * (e.g. REPEATABLE-READ in innodb), so the "real" lag of that data
3011          * is this lag plus transaction duration. If they don't, it is still
3012          * safe to be pessimistic. This returns null if there is no transaction.
3013          *
3014          * @return array|null ('lag': seconds or false on error, 'since': UNIX timestamp of BEGIN)
3015          * @since 1.27
3016          */
3017         protected function getTransactionLagStatus() {
3018                 return $this->mTrxLevel
3019                         ? [ 'lag' => $this->mTrxReplicaLag, 'since' => $this->trxTimestamp() ]
3020                         : null;
3021         }
3022
3023         /**
3024          * Get a replica DB lag estimate for this server
3025          *
3026          * @return array ('lag': seconds or false on error, 'since': UNIX timestamp of estimate)
3027          * @since 1.27
3028          */
3029         protected function getApproximateLagStatus() {
3030                 return [
3031                         'lag'   => $this->getLBInfo( 'replica' ) ? $this->getLag() : 0,
3032                         'since' => microtime( true )
3033                 ];
3034         }
3035
3036         /**
3037          * Merge the result of getSessionLagStatus() for several DBs
3038          * using the most pessimistic values to estimate the lag of
3039          * any data derived from them in combination
3040          *
3041          * This is information is useful for caching modules
3042          *
3043          * @see WANObjectCache::set()
3044          * @see WANObjectCache::getWithSetCallback()
3045          *
3046          * @param IDatabase $db1
3047          * @param IDatabase ...
3048          * @return array Map of values:
3049          *   - lag: highest lag of any of the DBs or false on error (e.g. replication stopped)
3050          *   - since: oldest UNIX timestamp of any of the DB lag estimates
3051          *   - pending: whether any of the DBs have uncommitted changes
3052          * @since 1.27
3053          */
3054         public static function getCacheSetOptions( IDatabase $db1 ) {
3055                 $res = [ 'lag' => 0, 'since' => INF, 'pending' => false ];
3056                 foreach ( func_get_args() as $db ) {
3057                         /** @var IDatabase $db */
3058                         $status = $db->getSessionLagStatus();
3059                         if ( $status['lag'] === false ) {
3060                                 $res['lag'] = false;
3061                         } elseif ( $res['lag'] !== false ) {
3062                                 $res['lag'] = max( $res['lag'], $status['lag'] );
3063                         }
3064                         $res['since'] = min( $res['since'], $status['since'] );
3065                         $res['pending'] = $res['pending'] ?: $db->writesPending();
3066                 }
3067
3068                 return $res;
3069         }
3070
3071         public function getLag() {
3072                 return 0;
3073         }
3074
3075         public function maxListLen() {
3076                 return 0;
3077         }
3078
3079         public function encodeBlob( $b ) {
3080                 return $b;
3081         }
3082
3083         public function decodeBlob( $b ) {
3084                 if ( $b instanceof Blob ) {
3085                         $b = $b->fetch();
3086                 }
3087                 return $b;
3088         }
3089
3090         public function setSessionOptions( array $options ) {
3091         }
3092
3093         public function sourceFile(
3094                 $filename,
3095                 callable $lineCallback = null,
3096                 callable $resultCallback = null,
3097                 $fname = false,
3098                 callable $inputCallback = null
3099         ) {
3100                 MediaWiki\suppressWarnings();
3101                 $fp = fopen( $filename, 'r' );
3102                 MediaWiki\restoreWarnings();
3103
3104                 if ( false === $fp ) {
3105                         throw new RuntimeException( "Could not open \"{$filename}\".\n" );
3106                 }
3107
3108                 if ( !$fname ) {
3109                         $fname = __METHOD__ . "( $filename )";
3110                 }
3111
3112                 try {
3113                         $error = $this->sourceStream(
3114                                 $fp, $lineCallback, $resultCallback, $fname, $inputCallback );
3115                 } catch ( Exception $e ) {
3116                         fclose( $fp );
3117                         throw $e;
3118                 }
3119
3120                 fclose( $fp );
3121
3122                 return $error;
3123         }
3124
3125         public function setSchemaVars( $vars ) {
3126                 $this->mSchemaVars = $vars;
3127         }
3128
3129         public function sourceStream(
3130                 $fp,
3131                 callable $lineCallback = null,
3132                 callable $resultCallback = null,
3133                 $fname = __METHOD__,
3134                 callable $inputCallback = null
3135         ) {
3136                 $cmd = '';
3137
3138                 while ( !feof( $fp ) ) {
3139                         if ( $lineCallback ) {
3140                                 call_user_func( $lineCallback );
3141                         }
3142
3143                         $line = trim( fgets( $fp ) );
3144
3145                         if ( $line == '' ) {
3146                                 continue;
3147                         }
3148
3149                         if ( '-' == $line[0] && '-' == $line[1] ) {
3150                                 continue;
3151                         }
3152
3153                         if ( $cmd != '' ) {
3154                                 $cmd .= ' ';
3155                         }
3156
3157                         $done = $this->streamStatementEnd( $cmd, $line );
3158
3159                         $cmd .= "$line\n";
3160
3161                         if ( $done || feof( $fp ) ) {
3162                                 $cmd = $this->replaceVars( $cmd );
3163
3164                                 if ( !$inputCallback || call_user_func( $inputCallback, $cmd ) ) {
3165                                         $res = $this->query( $cmd, $fname );
3166
3167                                         if ( $resultCallback ) {
3168                                                 call_user_func( $resultCallback, $res, $this );
3169                                         }
3170
3171                                         if ( false === $res ) {
3172                                                 $err = $this->lastError();
3173
3174                                                 return "Query \"{$cmd}\" failed with error code \"$err\".\n";
3175                                         }
3176                                 }
3177                                 $cmd = '';
3178                         }
3179                 }
3180
3181                 return true;
3182         }
3183
3184         /**
3185          * Called by sourceStream() to check if we've reached a statement end
3186          *
3187          * @param string &$sql SQL assembled so far
3188          * @param string &$newLine New line about to be added to $sql
3189          * @return bool Whether $newLine contains end of the statement
3190          */
3191         public function streamStatementEnd( &$sql, &$newLine ) {
3192                 if ( $this->delimiter ) {
3193                         $prev = $newLine;
3194                         $newLine = preg_replace(
3195                                 '/' . preg_quote( $this->delimiter, '/' ) . '$/', '', $newLine );
3196                         if ( $newLine != $prev ) {
3197                                 return true;
3198                         }
3199                 }
3200
3201                 return false;
3202         }
3203
3204         /**
3205          * Database independent variable replacement. Replaces a set of variables
3206          * in an SQL statement with their contents as given by $this->getSchemaVars().
3207          *
3208          * Supports '{$var}' `{$var}` and / *$var* / (without the spaces) style variables.
3209          *
3210          * - '{$var}' should be used for text and is passed through the database's
3211          *   addQuotes method.
3212          * - `{$var}` should be used for identifiers (e.g. table and database names).
3213          *   It is passed through the database's addIdentifierQuotes method which
3214          *   can be overridden if the database uses something other than backticks.
3215          * - / *_* / or / *$wgDBprefix* / passes the name that follows through the
3216          *   database's tableName method.
3217          * - / *i* / passes the name that follows through the database's indexName method.
3218          * - In all other cases, / *$var* / is left unencoded. Except for table options,
3219          *   its use should be avoided. In 1.24 and older, string encoding was applied.
3220          *
3221          * @param string $ins SQL statement to replace variables in
3222          * @return string The new SQL statement with variables replaced
3223          */
3224         protected function replaceVars( $ins ) {
3225                 $vars = $this->getSchemaVars();
3226                 return preg_replace_callback(
3227                         '!
3228                                 /\* (\$wgDBprefix|[_i]) \*/ (\w*) | # 1-2. tableName, indexName
3229                                 \'\{\$ (\w+) }\'                  | # 3. addQuotes
3230                                 `\{\$ (\w+) }`                    | # 4. addIdentifierQuotes
3231                                 /\*\$ (\w+) \*/                     # 5. leave unencoded
3232                         !x',
3233                         function ( $m ) use ( $vars ) {
3234                                 // Note: Because of <https://bugs.php.net/bug.php?id=51881>,
3235                                 // check for both nonexistent keys *and* the empty string.
3236                                 if ( isset( $m[1] ) && $m[1] !== '' ) {
3237                                         if ( $m[1] === 'i' ) {
3238                                                 return $this->indexName( $m[2] );
3239                                         } else {
3240                                                 return $this->tableName( $m[2] );
3241                                         }
3242                                 } elseif ( isset( $m[3] ) && $m[3] !== '' && array_key_exists( $m[3], $vars ) ) {
3243                                         return $this->addQuotes( $vars[$m[3]] );
3244                                 } elseif ( isset( $m[4] ) && $m[4] !== '' && array_key_exists( $m[4], $vars ) ) {
3245                                         return $this->addIdentifierQuotes( $vars[$m[4]] );
3246                                 } elseif ( isset( $m[5] ) && $m[5] !== '' && array_key_exists( $m[5], $vars ) ) {
3247                                         return $vars[$m[5]];
3248                                 } else {
3249                                         return $m[0];
3250                                 }
3251                         },
3252                         $ins
3253                 );
3254         }
3255
3256         /**
3257          * Get schema variables. If none have been set via setSchemaVars(), then
3258          * use some defaults from the current object.
3259          *
3260          * @return array
3261          */
3262         protected function getSchemaVars() {
3263                 if ( $this->mSchemaVars ) {
3264                         return $this->mSchemaVars;
3265                 } else {
3266                         return $this->getDefaultSchemaVars();
3267                 }
3268         }
3269
3270         /**
3271          * Get schema variables to use if none have been set via setSchemaVars().
3272          *
3273          * Override this in derived classes to provide variables for tables.sql
3274          * and SQL patch files.
3275          *
3276          * @return array
3277          */
3278         protected function getDefaultSchemaVars() {
3279                 return [];
3280         }
3281
3282         public function lockIsFree( $lockName, $method ) {
3283                 return true;
3284         }
3285
3286         public function lock( $lockName, $method, $timeout = 5 ) {
3287                 $this->mNamedLocksHeld[$lockName] = 1;
3288
3289                 return true;
3290         }
3291
3292         public function unlock( $lockName, $method ) {
3293                 unset( $this->mNamedLocksHeld[$lockName] );
3294
3295                 return true;
3296         }
3297
3298         public function getScopedLockAndFlush( $lockKey, $fname, $timeout ) {
3299                 if ( $this->writesOrCallbacksPending() ) {
3300                         // This only flushes transactions to clear snapshots, not to write data
3301                         $fnames = implode( ', ', $this->pendingWriteAndCallbackCallers() );
3302                         throw new DBUnexpectedError(
3303                                 $this,
3304                                 "$fname: Cannot flush pre-lock snapshot because writes are pending ($fnames)."
3305                         );
3306                 }
3307
3308                 if ( !$this->lock( $lockKey, $fname, $timeout ) ) {
3309                         return null;
3310                 }
3311
3312                 $unlocker = new ScopedCallback( function () use ( $lockKey, $fname ) {
3313                         if ( $this->trxLevel() ) {
3314                                 // There is a good chance an exception was thrown, causing any early return
3315                                 // from the caller. Let any error handler get a chance to issue rollback().
3316                                 // If there isn't one, let the error bubble up and trigger server-side rollback.
3317                                 $this->onTransactionResolution(
3318                                         function () use ( $lockKey, $fname ) {
3319                                                 $this->unlock( $lockKey, $fname );
3320                                         },
3321                                         $fname
3322                                 );
3323                         } else {
3324                                 $this->unlock( $lockKey, $fname );
3325                         }
3326                 } );
3327
3328                 $this->commit( $fname, self::FLUSHING_INTERNAL );
3329
3330                 return $unlocker;
3331         }
3332
3333         public function namedLocksEnqueue() {
3334                 return false;
3335         }
3336
3337         public function tableLocksHaveTransactionScope() {
3338                 return true;
3339         }
3340
3341         final public function lockTables( array $read, array $write, $method ) {
3342                 if ( $this->writesOrCallbacksPending() ) {
3343                         throw new DBUnexpectedError( $this, "Transaction writes or callbacks still pending." );
3344                 }
3345
3346                 if ( $this->tableLocksHaveTransactionScope() ) {
3347                         $this->startAtomic( $method );
3348                 }
3349
3350                 return $this->doLockTables( $read, $write, $method );
3351         }
3352
3353         protected function doLockTables( array $read, array $write, $method ) {
3354                 return true;
3355         }
3356
3357         final public function unlockTables( $method ) {
3358                 if ( $this->tableLocksHaveTransactionScope() ) {
3359                         $this->endAtomic( $method );
3360
3361                         return true; // locks released on COMMIT/ROLLBACK
3362                 }
3363
3364                 return $this->doUnlockTables( $method );
3365         }
3366
3367         protected function doUnlockTables( $method ) {
3368                 return true;
3369         }
3370
3371         /**
3372          * Delete a table
3373          * @param string $tableName
3374          * @param string $fName
3375          * @return bool|ResultWrapper
3376          * @since 1.18
3377          */
3378         public function dropTable( $tableName, $fName = __METHOD__ ) {
3379                 if ( !$this->tableExists( $tableName, $fName ) ) {
3380                         return false;
3381                 }
3382                 $sql = "DROP TABLE " . $this->tableName( $tableName ) . " CASCADE";
3383
3384                 return $this->query( $sql, $fName );
3385         }
3386
3387         public function getInfinity() {
3388                 return 'infinity';
3389         }
3390
3391         public function encodeExpiry( $expiry ) {
3392                 return ( $expiry == '' || $expiry == 'infinity' || $expiry == $this->getInfinity() )
3393                         ? $this->getInfinity()
3394                         : $this->timestamp( $expiry );
3395         }
3396
3397         public function decodeExpiry( $expiry, $format = TS_MW ) {
3398                 if ( $expiry == '' || $expiry == 'infinity' || $expiry == $this->getInfinity() ) {
3399                         return 'infinity';
3400                 }
3401
3402                 return ConvertibleTimestamp::convert( $format, $expiry );
3403         }
3404
3405         public function setBigSelects( $value = true ) {
3406                 // no-op
3407         }
3408
3409         public function isReadOnly() {
3410                 return ( $this->getReadOnlyReason() !== false );
3411         }
3412
3413         /**
3414          * @return string|bool Reason this DB is read-only or false if it is not
3415          */
3416         protected function getReadOnlyReason() {
3417                 $reason = $this->getLBInfo( 'readOnlyReason' );
3418
3419                 return is_string( $reason ) ? $reason : false;
3420         }
3421
3422         public function setTableAliases( array $aliases ) {
3423                 $this->tableAliases = $aliases;
3424         }
3425
3426         /**
3427          * @return bool Whether a DB user is required to access the DB
3428          * @since 1.28
3429          */
3430         protected function requiresDatabaseUser() {
3431                 return true;
3432         }
3433
3434         /**
3435          * Get the underlying binding handle, mConn
3436          *
3437          * Makes sure that mConn is set (disconnects and ping() failure can unset it).
3438          * This catches broken callers than catch and ignore disconnection exceptions.
3439          * Unlike checking isOpen(), this is safe to call inside of open().
3440          *
3441          * @return resource|object
3442          * @throws DBUnexpectedError
3443          * @since 1.26
3444          */
3445         protected function getBindingHandle() {
3446                 if ( !$this->mConn ) {
3447                         throw new DBUnexpectedError(
3448                                 $this,
3449                                 'DB connection was already closed or the connection dropped.'
3450                         );
3451                 }
3452
3453                 return $this->mConn;
3454         }
3455
3456         /**
3457          * @since 1.19
3458          * @return string
3459          */
3460         public function __toString() {
3461                 return (string)$this->mConn;
3462         }
3463
3464         /**
3465          * Make sure that copies do not share the same client binding handle
3466          * @throws DBConnectionError
3467          */
3468         public function __clone() {
3469                 $this->connLogger->warning(
3470                         "Cloning " . static::class . " is not recomended; forking connection:\n" .
3471                         ( new RuntimeException() )->getTraceAsString()
3472                 );
3473
3474                 if ( $this->isOpen() ) {
3475                         // Open a new connection resource without messing with the old one
3476                         $this->mOpened = false;
3477                         $this->mConn = false;
3478                         $this->mTrxEndCallbacks = []; // don't copy
3479                         $this->handleSessionLoss(); // no trx or locks anymore
3480                         $this->open( $this->mServer, $this->mUser, $this->mPassword, $this->mDBname );
3481                         $this->lastPing = microtime( true );
3482                 }
3483         }
3484
3485         /**
3486          * Called by serialize. Throw an exception when DB connection is serialized.
3487          * This causes problems on some database engines because the connection is
3488          * not restored on unserialize.
3489          */
3490         public function __sleep() {
3491                 throw new RuntimeException( 'Database serialization may cause problems, since ' .
3492                         'the connection is not restored on wakeup.' );
3493         }
3494
3495         /**
3496          * Run a few simple sanity checks and close dangling connections
3497          */
3498         public function __destruct() {
3499                 if ( $this->mTrxLevel && $this->mTrxDoneWrites ) {
3500                         trigger_error( "Uncommitted DB writes (transaction from {$this->mTrxFname})." );
3501                 }
3502
3503                 $danglingWriters = $this->pendingWriteAndCallbackCallers();
3504                 if ( $danglingWriters ) {
3505                         $fnames = implode( ', ', $danglingWriters );
3506                         trigger_error( "DB transaction writes or callbacks still pending ($fnames)." );
3507                 }
3508
3509                 if ( $this->mConn ) {
3510                         // Avoid connection leaks for sanity. Normally, resources close at script completion.
3511                         // The connection might already be closed in zend/hhvm by now, so suppress warnings.
3512                         \MediaWiki\suppressWarnings();
3513                         $this->closeConnection();
3514                         \MediaWiki\restoreWarnings();
3515                         $this->mConn = false;
3516                         $this->mOpened = false;
3517                 }
3518         }
3519 }
3520
3521 class_alias( Database::class, 'DatabaseBase' ); // b/c for old name
3522 class_alias( Database::class, 'Database' ); // b/c global alias