includes/libs/rdbms/database/Database.php

   1 <?php
   2 /**
   3  * @defgroup Database Database
   4  *
   5  * This file deals with database interface functions
   6  * and query specifics/optimisations.
   7  *
   8  * This program is free software; you can redistribute it and/or modify
   9  * it under the terms of the GNU General Public License as published by
  10  * the Free Software Foundation; either version 2 of the License, or
  11  * (at your option) any later version.
  12  *
  13  * This program is distributed in the hope that it will be useful,
  14  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  15  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
  16  * GNU General Public License for more details.
  17  *
  18  * You should have received a copy of the GNU General Public License along
  19  * with this program; if not, write to the Free Software Foundation, Inc.,
  20  * 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
  21  * http://www.gnu.org/copyleft/gpl.html
  22  *
  23  * @file
  24  * @ingroup Database
  25  */
  26 namespace Wikimedia\Rdbms;
  27
  28 use Psr\Log\LoggerAwareInterface;
  29 use Psr\Log\LoggerInterface;
  30 use Wikimedia\ScopedCallback;
  31 use Wikimedia\Timestamp\ConvertibleTimestamp;
  32 use MediaWiki;
  33 use BagOStuff;
  34 use HashBagOStuff;
  35 use InvalidArgumentException;
  36 use Exception;
  37 use RuntimeException;
  38
  39 /**
  40  * Relational database abstraction object
  41  *
  42  * @ingroup Database
  43  * @since 1.28
  44  */
  45 abstract class Database implements IDatabase, IMaintainableDatabase, LoggerAwareInterface {
  46         /** Number of times to re-try an operation in case of deadlock */
  47         const DEADLOCK_TRIES = 4;
  48         /** Minimum time to wait before retry, in microseconds */
  49         const DEADLOCK_DELAY_MIN = 500000;
  50         /** Maximum time to wait before retry */
  51         const DEADLOCK_DELAY_MAX = 1500000;
  52
  53         /** How long before it is worth doing a dummy query to test the connection */
  54         const PING_TTL = 1.0;
  55         const PING_QUERY = 'SELECT 1 AS ping';
  56
  57         const TINY_WRITE_SEC = .010;
  58         const SLOW_WRITE_SEC = .500;
  59         const SMALL_WRITE_ROWS = 100;
  60
  61         /** @var string SQL query */
  62         protected $mLastQuery = '';
  63         /** @var float|bool UNIX timestamp of last write query */
  64         protected $mLastWriteTime = false;
  65         /** @var string|bool */
  66         protected $mPHPError = false;
  67         /** @var string */
  68         protected $mServer;
  69         /** @var string */
  70         protected $mUser;
  71         /** @var string */
  72         protected $mPassword;
  73         /** @var string */
  74         protected $mDBname;
  75         /** @var array[] $aliases Map of (table => (dbname, schema, prefix) map) */
  76         protected $tableAliases = [];
  77         /** @var bool Whether this PHP instance is for a CLI script */
  78         protected $cliMode;
  79         /** @var string Agent name for query profiling */
  80         protected $agent;
  81
  82         /** @var BagOStuff APC cache */
  83         protected $srvCache;
  84         /** @var LoggerInterface */
  85         protected $connLogger;
  86         /** @var LoggerInterface */
  87         protected $queryLogger;
  88         /** @var callback Error logging callback */
  89         protected $errorLogger;
  90
  91         /** @var resource|null Database connection */
  92         protected $mConn = null;
  93         /** @var bool */
  94         protected $mOpened = false;
  95
  96         /** @var array[] List of (callable, method name) */
  97         protected $mTrxIdleCallbacks = [];
  98         /** @var array[] List of (callable, method name) */
  99         protected $mTrxPreCommitCallbacks = [];
 100         /** @var array[] List of (callable, method name) */
 101         protected $mTrxEndCallbacks = [];
 102         /** @var callable[] Map of (name => callable) */
 103         protected $mTrxRecurringCallbacks = [];
 104         /** @var bool Whether to suppress triggering of transaction end callbacks */
 105         protected $mTrxEndCallbacksSuppressed = false;
 106
 107         /** @var string */
 108         protected $mTablePrefix = '';
 109         /** @var string */
 110         protected $mSchema = '';
 111         /** @var integer */
 112         protected $mFlags;
 113         /** @var array */
 114         protected $mLBInfo = [];
 115         /** @var bool|null */
 116         protected $mDefaultBigSelects = null;
 117         /** @var array|bool */
 118         protected $mSchemaVars = false;
 119         /** @var array */
 120         protected $mSessionVars = [];
 121         /** @var array|null */
 122         protected $preparedArgs;
 123         /** @var string|bool|null Stashed value of html_errors INI setting */
 124         protected $htmlErrors;
 125         /** @var string */
 126         protected $delimiter = ';';
 127         /** @var DatabaseDomain */
 128         protected $currentDomain;
 129
 130         /**
 131          * Either 1 if a transaction is active or 0 otherwise.
 132          * The other Trx fields may not be meaningfull if this is 0.
 133          *
 134          * @var int
 135          */
 136         protected $mTrxLevel = 0;
 137         /**
 138          * Either a short hexidecimal string if a transaction is active or ""
 139          *
 140          * @var string
 141          * @see Database::mTrxLevel
 142          */
 143         protected $mTrxShortId = '';
 144         /**
 145          * The UNIX time that the transaction started. Callers can assume that if
 146          * snapshot isolation is used, then the data is *at least* up to date to that
 147          * point (possibly more up-to-date since the first SELECT defines the snapshot).
 148          *
 149          * @var float|null
 150          * @see Database::mTrxLevel
 151          */
 152         private $mTrxTimestamp = null;
 153         /** @var float Lag estimate at the time of BEGIN */
 154         private $mTrxReplicaLag = null;
 155         /**
 156          * Remembers the function name given for starting the most recent transaction via begin().
 157          * Used to provide additional context for error reporting.
 158          *
 159          * @var string
 160          * @see Database::mTrxLevel
 161          */
 162         private $mTrxFname = null;
 163         /**
 164          * Record if possible write queries were done in the last transaction started
 165          *
 166          * @var bool
 167          * @see Database::mTrxLevel
 168          */
 169         private $mTrxDoneWrites = false;
 170         /**
 171          * Record if the current transaction was started implicitly due to DBO_TRX being set.
 172          *
 173          * @var bool
 174          * @see Database::mTrxLevel
 175          */
 176         private $mTrxAutomatic = false;
 177         /**
 178          * Array of levels of atomicity within transactions
 179          *
 180          * @var array
 181          */
 182         private $mTrxAtomicLevels = [];
 183         /**
 184          * Record if the current transaction was started implicitly by Database::startAtomic
 185          *
 186          * @var bool
 187          */
 188         private $mTrxAutomaticAtomic = false;
 189         /**
 190          * Track the write query callers of the current transaction
 191          *
 192          * @var string[]
 193          */
 194         private $mTrxWriteCallers = [];
 195         /**
 196          * @var float Seconds spent in write queries for the current transaction
 197          */
 198         private $mTrxWriteDuration = 0.0;
 199         /**
 200          * @var integer Number of write queries for the current transaction
 201          */
 202         private $mTrxWriteQueryCount = 0;
 203         /**
 204          * @var float Like mTrxWriteQueryCount but excludes lock-bound, easy to replicate, queries
 205          */
 206         private $mTrxWriteAdjDuration = 0.0;
 207         /**
 208          * @var integer Number of write queries counted in mTrxWriteAdjDuration
 209          */
 210         private $mTrxWriteAdjQueryCount = 0;
 211         /**
 212          * @var float RTT time estimate
 213          */
 214         private $mRTTEstimate = 0.0;
 215
 216         /** @var array Map of (name => 1) for locks obtained via lock() */
 217         private $mNamedLocksHeld = [];
 218         /** @var array Map of (table name => 1) for TEMPORARY tables */
 219         protected $mSessionTempTables = [];
 220
 221         /** @var IDatabase|null Lazy handle to the master DB this server replicates from */
 222         private $lazyMasterHandle;
 223
 224         /** @var float UNIX timestamp */
 225         protected $lastPing = 0.0;
 226
 227         /** @var int[] Prior mFlags values */
 228         private $priorFlags = [];
 229
 230         /** @var object|string Class name or object With profileIn/profileOut methods */
 231         protected $profiler;
 232         /** @var TransactionProfiler */
 233         protected $trxProfiler;
 234
 235         /**
 236          * Constructor and database handle and attempt to connect to the DB server
 237          *
 238          * IDatabase classes should not be constructed directly in external
 239          * code. Database::factory() should be used instead.
 240          *
 241          * @param array $params Parameters passed from Database::factory()
 242          */
 243         function __construct( array $params ) {
 244                 $server = $params['host'];
 245                 $user = $params['user'];
 246                 $password = $params['password'];
 247                 $dbName = $params['dbname'];
 248
 249                 $this->mSchema = $params['schema'];
 250                 $this->mTablePrefix = $params['tablePrefix'];
 251
 252                 $this->cliMode = $params['cliMode'];
 253                 // Agent name is added to SQL queries in a comment, so make sure it can't break out
 254                 $this->agent = str_replace( '/', '-', $params['agent'] );
 255
 256                 $this->mFlags = $params['flags'];
 257                 if ( $this->mFlags & self::DBO_DEFAULT ) {
 258                         if ( $this->cliMode ) {
 259                                 $this->mFlags &= ~self::DBO_TRX;
 260                         } else {
 261                                 $this->mFlags |= self::DBO_TRX;
 262                         }
 263                 }
 264
 265                 $this->mSessionVars = $params['variables'];
 266
 267                 $this->srvCache = isset( $params['srvCache'] )
 268                         ? $params['srvCache']
 269                         : new HashBagOStuff();
 270
 271                 $this->profiler = $params['profiler'];
 272                 $this->trxProfiler = $params['trxProfiler'];
 273                 $this->connLogger = $params['connLogger'];
 274                 $this->queryLogger = $params['queryLogger'];
 275                 $this->errorLogger = $params['errorLogger'];
 276
 277                 // Set initial dummy domain until open() sets the final DB/prefix
 278                 $this->currentDomain = DatabaseDomain::newUnspecified();
 279
 280                 if ( $user ) {
 281                         $this->open( $server, $user, $password, $dbName );
 282                 } elseif ( $this->requiresDatabaseUser() ) {
 283                         throw new InvalidArgumentException( "No database user provided." );
 284                 }
 285
 286                 // Set the domain object after open() sets the relevant fields
 287                 if ( $this->mDBname != '' ) {
 288                         // Domains with server scope but a table prefix are not used by IDatabase classes
 289                         $this->currentDomain = new DatabaseDomain( $this->mDBname, null, $this->mTablePrefix );
 290                 }
 291         }
 292
 293         /**
 294          * Construct a Database subclass instance given a database type and parameters
 295          *
 296          * This also connects to the database immediately upon object construction
 297          *
 298          * @param string $dbType A possible DB type (sqlite, mysql, postgres)
 299          * @param array $p Parameter map with keys:
 300          *   - host : The hostname of the DB server
 301          *   - user : The name of the database user the client operates under
 302          *   - password : The password for the database user
 303          *   - dbname : The name of the database to use where queries do not specify one.
 304          *      The database must exist or an error might be thrown. Setting this to the empty string
 305          *      will avoid any such errors and make the handle have no implicit database scope. This is
 306          *      useful for queries like SHOW STATUS, CREATE DATABASE, or DROP DATABASE. Note that a
 307          *      "database" in Postgres is rougly equivalent to an entire MySQL server. This the domain
 308          *      in which user names and such are defined, e.g. users are database-specific in Postgres.
 309          *   - schema : The database schema to use (if supported). A "schema" in Postgres is roughly
 310          *      equivalent to a "database" in MySQL. Note that MySQL and SQLite do not use schemas.
 311          *   - tablePrefix : Optional table prefix that is implicitly added on to all table names
 312          *      recognized in queries. This can be used in place of schemas for handle site farms.
 313          *   - flags : Optional bitfield of DBO_* constants that define connection, protocol,
 314          *      buffering, and transaction behavior. It is STRONGLY adviced to leave the DBO_DEFAULT
 315          *      flag in place UNLESS this this database simply acts as a key/value store.
 316          *   - driver: Optional name of a specific DB client driver. For MySQL, there is the old
 317          *      'mysql' driver and the newer 'mysqli' driver.
 318          *   - variables: Optional map of session variables to set after connecting. This can be
 319          *      used to adjust lock timeouts or encoding modes and the like.
 320          *   - connLogger: Optional PSR-3 logger interface instance.
 321          *   - queryLogger: Optional PSR-3 logger interface instance.
 322          *   - profiler: Optional class name or object with profileIn()/profileOut() methods.
 323          *      These will be called in query(), using a simplified version of the SQL that also
 324          *      includes the agent as a SQL comment.
 325          *   - trxProfiler: Optional TransactionProfiler instance.
 326          *   - errorLogger: Optional callback that takes an Exception and logs it.
 327          *   - cliMode: Whether to consider the execution context that of a CLI script.
 328          *   - agent: Optional name used to identify the end-user in query profiling/logging.
 329          *   - srvCache: Optional BagOStuff instance to an APC-style cache.
 330          * @return Database|null If the database driver or extension cannot be found
 331          * @throws InvalidArgumentException If the database driver or extension cannot be found
 332          * @since 1.18
 333          */
 334         final public static function factory( $dbType, $p = [] ) {
 335                 static $canonicalDBTypes = [
 336                         'mysql' => [ 'mysqli', 'mysql' ],
 337                         'postgres' => [],
 338                         'sqlite' => [],
 339                         'oracle' => [],
 340                         'mssql' => [],
 341                 ];
 342                 static $classAliases = [
 343                         'DatabaseMssql' => DatabaseMssql::class,
 344                         'DatabaseMysql' => DatabaseMysql::class,
 345                         'DatabaseMysqli' => DatabaseMysqli::class,
 346                         'DatabaseSqlite' => DatabaseSqlite::class,
 347                         'DatabasePostgres' => DatabasePostgres::class
 348                 ];
 349
 350                 $driver = false;
 351                 $dbType = strtolower( $dbType );
 352                 if ( isset( $canonicalDBTypes[$dbType] ) && $canonicalDBTypes[$dbType] ) {
 353                         $possibleDrivers = $canonicalDBTypes[$dbType];
 354                         if ( !empty( $p['driver'] ) ) {
 355                                 if ( in_array( $p['driver'], $possibleDrivers ) ) {
 356                                         $driver = $p['driver'];
 357                                 } else {
 358                                         throw new InvalidArgumentException( __METHOD__ .
 359                                                 " type '$dbType' does not support driver '{$p['driver']}'" );
 360                                 }
 361                         } else {
 362                                 foreach ( $possibleDrivers as $posDriver ) {
 363                                         if ( extension_loaded( $posDriver ) ) {
 364                                                 $driver = $posDriver;
 365                                                 break;
 366                                         }
 367                                 }
 368                         }
 369                 } else {
 370                         $driver = $dbType;
 371                 }
 372
 373                 if ( $driver === false || $driver === '' ) {
 374                         throw new InvalidArgumentException( __METHOD__ .
 375                                 " no viable database extension found for type '$dbType'" );
 376                 }
 377
 378                 $class = 'Database' . ucfirst( $driver );
 379                 if ( isset( $classAliases[$class] ) ) {
 380                         $class = $classAliases[$class];
 381                 }
 382
 383                 if ( class_exists( $class ) && is_subclass_of( $class, IDatabase::class ) ) {
 384                         // Resolve some defaults for b/c
 385                         $p['host'] = isset( $p['host'] ) ? $p['host'] : false;
 386                         $p['user'] = isset( $p['user'] ) ? $p['user'] : false;
 387                         $p['password'] = isset( $p['password'] ) ? $p['password'] : false;
 388                         $p['dbname'] = isset( $p['dbname'] ) ? $p['dbname'] : false;
 389                         $p['flags'] = isset( $p['flags'] ) ? $p['flags'] : 0;
 390                         $p['variables'] = isset( $p['variables'] ) ? $p['variables'] : [];
 391                         $p['tablePrefix'] = isset( $p['tablePrefix'] ) ? $p['tablePrefix'] : '';
 392                         $p['schema'] = isset( $p['schema'] ) ? $p['schema'] : '';
 393                         $p['cliMode'] = isset( $p['cliMode'] ) ? $p['cliMode'] : ( PHP_SAPI === 'cli' );
 394                         $p['agent'] = isset( $p['agent'] ) ? $p['agent'] : '';
 395                         if ( !isset( $p['connLogger'] ) ) {
 396                                 $p['connLogger'] = new \Psr\Log\NullLogger();
 397                         }
 398                         if ( !isset( $p['queryLogger'] ) ) {
 399                                 $p['queryLogger'] = new \Psr\Log\NullLogger();
 400                         }
 401                         $p['profiler'] = isset( $p['profiler'] ) ? $p['profiler'] : null;
 402                         if ( !isset( $p['trxProfiler'] ) ) {
 403                                 $p['trxProfiler'] = new TransactionProfiler();
 404                         }
 405                         if ( !isset( $p['errorLogger'] ) ) {
 406                                 $p['errorLogger'] = function ( Exception $e ) {
 407                                         trigger_error( get_class( $e ) . ': ' . $e->getMessage(), E_USER_WARNING );
 408                                 };
 409                         }
 410
 411                         $conn = new $class( $p );
 412                 } else {
 413                         $conn = null;
 414                 }
 415
 416                 return $conn;
 417         }
 418
 419         public function setLogger( LoggerInterface $logger ) {
 420                 $this->queryLogger = $logger;
 421         }
 422
 423         public function getServerInfo() {
 424                 return $this->getServerVersion();
 425         }
 426
 427         public function bufferResults( $buffer = null ) {
 428                 $res = !$this->getFlag( self::DBO_NOBUFFER );
 429                 if ( $buffer !== null ) {
 430                         $buffer
 431                                 ? $this->clearFlag( self::DBO_NOBUFFER )
 432                                 : $this->setFlag( self::DBO_NOBUFFER );
 433                 }
 434
 435                 return $res;
 436         }
 437
 438         /**
 439          * Turns on (false) or off (true) the automatic generation and sending
 440          * of a "we're sorry, but there has been a database error" page on
 441          * database errors. Default is on (false). When turned off, the
 442          * code should use lastErrno() and lastError() to handle the
 443          * situation as appropriate.
 444          *
 445          * Do not use this function outside of the Database classes.
 446          *
 447          * @param null|bool $ignoreErrors
 448          * @return bool The previous value of the flag.
 449          */
 450         protected function ignoreErrors( $ignoreErrors = null ) {
 451                 $res = $this->getFlag( self::DBO_IGNORE );
 452                 if ( $ignoreErrors !== null ) {
 453                         $ignoreErrors
 454                                 ? $this->setFlag( self::DBO_IGNORE )
 455                                 : $this->clearFlag( self::DBO_IGNORE );
 456                 }
 457
 458                 return $res;
 459         }
 460
 461         public function trxLevel() {
 462                 return $this->mTrxLevel;
 463         }
 464
 465         public function trxTimestamp() {
 466                 return $this->mTrxLevel ? $this->mTrxTimestamp : null;
 467         }
 468
 469         public function tablePrefix( $prefix = null ) {
 470                 $old = $this->mTablePrefix;
 471                 if ( $prefix !== null ) {
 472                         $this->mTablePrefix = $prefix;
 473                         $this->currentDomain = ( $this->mDBname != '' )
 474                                 ? new DatabaseDomain( $this->mDBname, null, $this->mTablePrefix )
 475                                 : DatabaseDomain::newUnspecified();
 476                 }
 477
 478                 return $old;
 479         }
 480
 481         public function dbSchema( $schema = null ) {
 482                 $old = $this->mSchema;
 483                 if ( $schema !== null ) {
 484                         $this->mSchema = $schema;
 485                 }
 486
 487                 return $old;
 488         }
 489
 490         public function getLBInfo( $name = null ) {
 491                 if ( is_null( $name ) ) {
 492                         return $this->mLBInfo;
 493                 } else {
 494                         if ( array_key_exists( $name, $this->mLBInfo ) ) {
 495                                 return $this->mLBInfo[$name];
 496                         } else {
 497                                 return null;
 498                         }
 499                 }
 500         }
 501
 502         public function setLBInfo( $name, $value = null ) {
 503                 if ( is_null( $value ) ) {
 504                         $this->mLBInfo = $name;
 505                 } else {
 506                         $this->mLBInfo[$name] = $value;
 507                 }
 508         }
 509
 510         public function setLazyMasterHandle( IDatabase $conn ) {
 511                 $this->lazyMasterHandle = $conn;
 512         }
 513
 514         /**
 515          * @return IDatabase|null
 516          * @see setLazyMasterHandle()
 517          * @since 1.27
 518          */
 519         protected function getLazyMasterHandle() {
 520                 return $this->lazyMasterHandle;
 521         }
 522
 523         public function implicitGroupby() {
 524                 return true;
 525         }
 526
 527         public function implicitOrderby() {
 528                 return true;
 529         }
 530
 531         public function lastQuery() {
 532                 return $this->mLastQuery;
 533         }
 534
 535         public function doneWrites() {
 536                 return (bool)$this->mLastWriteTime;
 537         }
 538
 539         public function lastDoneWrites() {
 540                 return $this->mLastWriteTime ?: false;
 541         }
 542
 543         public function writesPending() {
 544                 return $this->mTrxLevel && $this->mTrxDoneWrites;
 545         }
 546
 547         public function writesOrCallbacksPending() {
 548                 return $this->mTrxLevel && (
 549                         $this->mTrxDoneWrites || $this->mTrxIdleCallbacks || $this->mTrxPreCommitCallbacks
 550                 );
 551         }
 552
 553         public function pendingWriteQueryDuration( $type = self::ESTIMATE_TOTAL ) {
 554                 if ( !$this->mTrxLevel ) {
 555                         return false;
 556                 } elseif ( !$this->mTrxDoneWrites ) {
 557                         return 0.0;
 558                 }
 559
 560                 switch ( $type ) {
 561                         case self::ESTIMATE_DB_APPLY:
 562                                 $this->ping( $rtt );
 563                                 $rttAdjTotal = $this->mTrxWriteAdjQueryCount * $rtt;
 564                                 $applyTime = max( $this->mTrxWriteAdjDuration - $rttAdjTotal, 0 );
 565                                 // For omitted queries, make them count as something at least
 566                                 $omitted = $this->mTrxWriteQueryCount - $this->mTrxWriteAdjQueryCount;
 567                                 $applyTime += self::TINY_WRITE_SEC * $omitted;
 568
 569                                 return $applyTime;
 570                         default: // everything
 571                                 return $this->mTrxWriteDuration;
 572                 }
 573         }
 574
 575         public function pendingWriteCallers() {
 576                 return $this->mTrxLevel ? $this->mTrxWriteCallers : [];
 577         }
 578
 579         protected function pendingWriteAndCallbackCallers() {
 580                 if ( !$this->mTrxLevel ) {
 581                         return [];
 582                 }
 583
 584                 $fnames = $this->mTrxWriteCallers;
 585                 foreach ( [
 586                         $this->mTrxIdleCallbacks,
 587                         $this->mTrxPreCommitCallbacks,
 588                         $this->mTrxEndCallbacks
 589                 ] as $callbacks ) {
 590                         foreach ( $callbacks as $callback ) {
 591                                 $fnames[] = $callback[1];
 592                         }
 593                 }
 594
 595                 return $fnames;
 596         }
 597
 598         public function isOpen() {
 599                 return $this->mOpened;
 600         }
 601
 602         public function setFlag( $flag, $remember = self::REMEMBER_NOTHING ) {
 603                 if ( $remember === self::REMEMBER_PRIOR ) {
 604                         array_push( $this->priorFlags, $this->mFlags );
 605                 }
 606                 $this->mFlags |= $flag;
 607         }
 608
 609         public function clearFlag( $flag, $remember = self::REMEMBER_NOTHING ) {
 610                 if ( $remember === self::REMEMBER_PRIOR ) {
 611                         array_push( $this->priorFlags, $this->mFlags );
 612                 }
 613                 $this->mFlags &= ~$flag;
 614         }
 615
 616         public function restoreFlags( $state = self::RESTORE_PRIOR ) {
 617                 if ( !$this->priorFlags ) {
 618                         return;
 619                 }
 620
 621                 if ( $state === self::RESTORE_INITIAL ) {
 622                         $this->mFlags = reset( $this->priorFlags );
 623                         $this->priorFlags = [];
 624                 } else {
 625                         $this->mFlags = array_pop( $this->priorFlags );
 626                 }
 627         }
 628
 629         public function getFlag( $flag ) {
 630                 return !!( $this->mFlags & $flag );
 631         }
 632
 633         /**
 634          * @param string $name Class field name
 635          * @return mixed
 636          * @deprecated Since 1.28
 637          */
 638         public function getProperty( $name ) {
 639                 return $this->$name;
 640         }
 641
 642         public function getDomainID() {
 643                 return $this->currentDomain->getId();
 644         }
 645
 646         final public function getWikiID() {
 647                 return $this->getDomainID();
 648         }
 649
 650         /**
 651          * Get information about an index into an object
 652          * @param string $table Table name
 653          * @param string $index Index name
 654          * @param string $fname Calling function name
 655          * @return mixed Database-specific index description class or false if the index does not exist
 656          */
 657         abstract function indexInfo( $table, $index, $fname = __METHOD__ );
 658
 659         /**
 660          * Wrapper for addslashes()
 661          *
 662          * @param string $s String to be slashed.
 663          * @return string Slashed string.
 664          */
 665         abstract function strencode( $s );
 666
 667         protected function installErrorHandler() {
 668                 $this->mPHPError = false;
 669                 $this->htmlErrors = ini_set( 'html_errors', '0' );
 670                 set_error_handler( [ $this, 'connectionErrorLogger' ] );
 671         }
 672
 673         /**
 674          * @return bool|string
 675          */
 676         protected function restoreErrorHandler() {
 677                 restore_error_handler();
 678                 if ( $this->htmlErrors !== false ) {
 679                         ini_set( 'html_errors', $this->htmlErrors );
 680                 }
 681
 682                 return $this->getLastPHPError();
 683         }
 684
 685         /**
 686          * @return string|bool Last PHP error for this DB (typically connection errors)
 687          */
 688         protected function getLastPHPError() {
 689                 if ( $this->mPHPError ) {
 690                         $error = preg_replace( '!\[<a.*</a>\]!', '', $this->mPHPError );
 691                         $error = preg_replace( '!^.*?:\s?(.*)$!', '$1', $error );
 692
 693                         return $error;
 694                 }
 695
 696                 return false;
 697         }
 698
 699         /**
 700          * This method should not be used outside of Database classes
 701          *
 702          * @param int $errno
 703          * @param string $errstr
 704          */
 705         public function connectionErrorLogger( $errno, $errstr ) {
 706                 $this->mPHPError = $errstr;
 707         }
 708
 709         /**
 710          * Create a log context to pass to PSR-3 logger functions.
 711          *
 712          * @param array $extras Additional data to add to context
 713          * @return array
 714          */
 715         protected function getLogContext( array $extras = [] ) {
 716                 return array_merge(
 717                         [
 718                                 'db_server' => $this->mServer,
 719                                 'db_name' => $this->mDBname,
 720                                 'db_user' => $this->mUser,
 721                         ],
 722                         $extras
 723                 );
 724         }
 725
 726         public function close() {
 727                 if ( $this->mConn ) {
 728                         if ( $this->trxLevel() ) {
 729                                 $this->commit( __METHOD__, self::FLUSHING_INTERNAL );
 730                         }
 731
 732                         $closed = $this->closeConnection();
 733                         $this->mConn = false;
 734                 } elseif ( $this->mTrxIdleCallbacks || $this->mTrxEndCallbacks ) { // sanity
 735                         throw new RuntimeException( "Transaction callbacks still pending." );
 736                 } else {
 737                         $closed = true;
 738                 }
 739                 $this->mOpened = false;
 740
 741                 return $closed;
 742         }
 743
 744         /**
 745          * Make sure isOpen() returns true as a sanity check
 746          *
 747          * @throws DBUnexpectedError
 748          */
 749         protected function assertOpen() {
 750                 if ( !$this->isOpen() ) {
 751                         throw new DBUnexpectedError( $this, "DB connection was already closed." );
 752                 }
 753         }
 754
 755         /**
 756          * Closes underlying database connection
 757          * @since 1.20
 758          * @return bool Whether connection was closed successfully
 759          */
 760         abstract protected function closeConnection();
 761
 762         public function reportConnectionError( $error = 'Unknown error' ) {
 763                 $myError = $this->lastError();
 764                 if ( $myError ) {
 765                         $error = $myError;
 766                 }
 767
 768                 # New method
 769                 throw new DBConnectionError( $this, $error );
 770         }
 771
 772         /**
 773          * The DBMS-dependent part of query()
 774          *
 775          * @param string $sql SQL query.
 776          * @return ResultWrapper|bool Result object to feed to fetchObject,
 777          *   fetchRow, ...; or false on failure
 778          */
 779         abstract protected function doQuery( $sql );
 780
 781         /**
 782          * Determine whether a query writes to the DB.
 783          * Should return true if unsure.
 784          *
 785          * @param string $sql
 786          * @return bool
 787          */
 788         protected function isWriteQuery( $sql ) {
 789                 return !preg_match(
 790                         '/^(?:SELECT|BEGIN|ROLLBACK|COMMIT|SET|SHOW|EXPLAIN|\(SELECT)\b/i', $sql );
 791         }
 792
 793         /**
 794          * @param $sql
 795          * @return string|null
 796          */
 797         protected function getQueryVerb( $sql ) {
 798                 return preg_match( '/^\s*([a-z]+)/i', $sql, $m ) ? strtoupper( $m[1] ) : null;
 799         }
 800
 801         /**
 802          * Determine whether a SQL statement is sensitive to isolation level.
 803          * A SQL statement is considered transactable if its result could vary
 804          * depending on the transaction isolation level. Operational commands
 805          * such as 'SET' and 'SHOW' are not considered to be transactable.
 806          *
 807          * @param string $sql
 808          * @return bool
 809          */
 810         protected function isTransactableQuery( $sql ) {
 811                 return !in_array(
 812                         $this->getQueryVerb( $sql ),
 813                         [ 'BEGIN', 'COMMIT', 'ROLLBACK', 'SHOW', 'SET', 'CREATE', 'ALTER' ],
 814                         true
 815                 );
 816         }
 817
 818         /**
 819          * @param string $sql A SQL query
 820          * @return bool Whether $sql is SQL for creating/dropping a new TEMPORARY table
 821          */
 822         protected function registerTempTableOperation( $sql ) {
 823                 if ( preg_match(
 824                         '/^CREATE\s+TEMPORARY\s+TABLE\s+(?:IF\s+NOT\s+EXISTS\s+)?[`"\']?(\w+)[`"\']?/i',
 825                         $sql,
 826                         $matches
 827                 ) ) {
 828                         $this->mSessionTempTables[$matches[1]] = 1;
 829
 830                         return true;
 831                 } elseif ( preg_match(
 832                         '/^DROP\s+(?:TEMPORARY\s+)?TABLE\s+(?:IF\s+EXISTS\s+)?[`"\']?(\w+)[`"\']?/i',
 833                         $sql,
 834                         $matches
 835                 ) ) {
 836                         unset( $this->mSessionTempTables[$matches[1]] );
 837
 838                         return true;
 839                 } elseif ( preg_match(
 840                         '/^(?:INSERT\s+(?:\w+\s+)?INTO|UPDATE|DELETE\s+FROM)\s+[`"\']?(\w+)[`"\']?/i',
 841                         $sql,
 842                         $matches
 843                 ) ) {
 844                         return isset( $this->mSessionTempTables[$matches[1]] );
 845                 }
 846
 847                 return false;
 848         }
 849
 850         public function query( $sql, $fname = __METHOD__, $tempIgnore = false ) {
 851                 $priorWritesPending = $this->writesOrCallbacksPending();
 852                 $this->mLastQuery = $sql;
 853
 854                 $isWrite = $this->isWriteQuery( $sql ) && !$this->registerTempTableOperation( $sql );
 855                 if ( $isWrite ) {
 856                         $reason = $this->getReadOnlyReason();
 857                         if ( $reason !== false ) {
 858                                 throw new DBReadOnlyError( $this, "Database is read-only: $reason" );
 859                         }
 860                         # Set a flag indicating that writes have been done
 861                         $this->mLastWriteTime = microtime( true );
 862                 }
 863
 864                 // Add trace comment to the begin of the sql string, right after the operator.
 865                 // Or, for one-word queries (like "BEGIN" or COMMIT") add it to the end (T44598)
 866                 $commentedSql = preg_replace( '/\s|$/', " /* $fname {$this->agent} */ ", $sql, 1 );
 867
 868                 # Start implicit transactions that wrap the request if DBO_TRX is enabled
 869                 if ( !$this->mTrxLevel && $this->getFlag( self::DBO_TRX )
 870                         && $this->isTransactableQuery( $sql )
 871                 ) {
 872                         $this->begin( __METHOD__ . " ($fname)", self::TRANSACTION_INTERNAL );
 873                         $this->mTrxAutomatic = true;
 874                 }
 875
 876                 # Keep track of whether the transaction has write queries pending
 877                 if ( $this->mTrxLevel && !$this->mTrxDoneWrites && $isWrite ) {
 878                         $this->mTrxDoneWrites = true;
 879                         $this->trxProfiler->transactionWritingIn(
 880                                 $this->mServer, $this->mDBname, $this->mTrxShortId );
 881                 }
 882
 883                 if ( $this->getFlag( self::DBO_DEBUG ) ) {
 884                         $this->queryLogger->debug( "{$this->mDBname} {$commentedSql}" );
 885                 }
 886
 887                 # Avoid fatals if close() was called
 888                 $this->assertOpen();
 889
 890                 # Send the query to the server
 891                 $ret = $this->doProfiledQuery( $sql, $commentedSql, $isWrite, $fname );
 892
 893                 # Try reconnecting if the connection was lost
 894                 if ( false === $ret && $this->wasErrorReissuable() ) {
 895                         $recoverable = $this->canRecoverFromDisconnect( $sql, $priorWritesPending );
 896                         # Stash the last error values before anything might clear them
 897                         $lastError = $this->lastError();
 898                         $lastErrno = $this->lastErrno();
 899                         # Update state tracking to reflect transaction loss due to disconnection
 900                         $this->handleSessionLoss();
 901                         if ( $this->reconnect() ) {
 902                                 $msg = __METHOD__ . ": lost connection to {$this->getServer()}; reconnected";
 903                                 $this->connLogger->warning( $msg );
 904                                 $this->queryLogger->warning(
 905                                         "$msg:\n" . ( new RuntimeException() )->getTraceAsString() );
 906
 907                                 if ( !$recoverable ) {
 908                                         # Callers may catch the exception and continue to use the DB
 909                                         $this->reportQueryError( $lastError, $lastErrno, $sql, $fname );
 910                                 } else {
 911                                         # Should be safe to silently retry the query
 912                                         $ret = $this->doProfiledQuery( $sql, $commentedSql, $isWrite, $fname );
 913                                 }
 914                         } else {
 915                                 $msg = __METHOD__ . ": lost connection to {$this->getServer()} permanently";
 916                                 $this->connLogger->error( $msg );
 917                         }
 918                 }
 919
 920                 if ( false === $ret ) {
 921                         # Deadlocks cause the entire transaction to abort, not just the statement.
 922                         # https://dev.mysql.com/doc/refman/5.7/en/innodb-error-handling.html
 923                         # https://www.postgresql.org/docs/9.1/static/explicit-locking.html
 924                         if ( $this->wasDeadlock() ) {
 925                                 if ( $this->explicitTrxActive() || $priorWritesPending ) {
 926                                         $tempIgnore = false; // not recoverable
 927                                 }
 928                                 # Update state tracking to reflect transaction loss
 929                                 $this->handleSessionLoss();
 930                         }
 931
 932                         $this->reportQueryError(
 933                                 $this->lastError(), $this->lastErrno(), $sql, $fname, $tempIgnore );
 934                 }
 935
 936                 $res = $this->resultObject( $ret );
 937
 938                 return $res;
 939         }
 940
 941         private function doProfiledQuery( $sql, $commentedSql, $isWrite, $fname ) {
 942                 $isMaster = !is_null( $this->getLBInfo( 'master' ) );
 943                 # generalizeSQL() will probably cut down the query to reasonable
 944                 # logging size most of the time. The substr is really just a sanity check.
 945                 if ( $isMaster ) {
 946                         $queryProf = 'query-m: ' . substr( self::generalizeSQL( $sql ), 0, 255 );
 947                 } else {
 948                         $queryProf = 'query: ' . substr( self::generalizeSQL( $sql ), 0, 255 );
 949                 }
 950
 951                 # Include query transaction state
 952                 $queryProf .= $this->mTrxShortId ? " [TRX#{$this->mTrxShortId}]" : "";
 953
 954                 $startTime = microtime( true );
 955                 if ( $this->profiler ) {
 956                         call_user_func( [ $this->profiler, 'profileIn' ], $queryProf );
 957                 }
 958                 $ret = $this->doQuery( $commentedSql );
 959                 if ( $this->profiler ) {
 960                         call_user_func( [ $this->profiler, 'profileOut' ], $queryProf );
 961                 }
 962                 $queryRuntime = max( microtime( true ) - $startTime, 0.0 );
 963
 964                 unset( $queryProfSection ); // profile out (if set)
 965
 966                 if ( $ret !== false ) {
 967                         $this->lastPing = $startTime;
 968                         if ( $isWrite && $this->mTrxLevel ) {
 969                                 $this->updateTrxWriteQueryTime( $sql, $queryRuntime );
 970                                 $this->mTrxWriteCallers[] = $fname;
 971                         }
 972                 }
 973
 974                 if ( $sql === self::PING_QUERY ) {
 975                         $this->mRTTEstimate = $queryRuntime;
 976                 }
 977
 978                 $this->trxProfiler->recordQueryCompletion(
 979                         $queryProf, $startTime, $isWrite, $this->affectedRows()
 980                 );
 981                 $this->queryLogger->debug( $sql, [
 982                         'method' => $fname,
 983                         'master' => $isMaster,
 984                         'runtime' => $queryRuntime,
 985                 ] );
 986
 987                 return $ret;
 988         }
 989
 990         /**
 991          * Update the estimated run-time of a query, not counting large row lock times
 992          *
 993          * LoadBalancer can be set to rollback transactions that will create huge replication
 994          * lag. It bases this estimate off of pendingWriteQueryDuration(). Certain simple
 995          * queries, like inserting a row can take a long time due to row locking. This method
 996          * uses some simple heuristics to discount those cases.
 997          *
 998          * @param string $sql A SQL write query
 999          * @param float $runtime Total runtime, including RTT
1000          */
1001         private function updateTrxWriteQueryTime( $sql, $runtime ) {
1002                 // Whether this is indicative of replica DB runtime (except for RBR or ws_repl)
1003                 $indicativeOfReplicaRuntime = true;
1004                 if ( $runtime > self::SLOW_WRITE_SEC ) {
1005                         $verb = $this->getQueryVerb( $sql );
1006                         // insert(), upsert(), replace() are fast unless bulky in size or blocked on locks
1007                         if ( $verb === 'INSERT' ) {
1008                                 $indicativeOfReplicaRuntime = $this->affectedRows() > self::SMALL_WRITE_ROWS;
1009                         } elseif ( $verb === 'REPLACE' ) {
1010                                 $indicativeOfReplicaRuntime = $this->affectedRows() > self::SMALL_WRITE_ROWS / 2;
1011                         }
1012                 }
1013
1014                 $this->mTrxWriteDuration += $runtime;
1015                 $this->mTrxWriteQueryCount += 1;
1016                 if ( $indicativeOfReplicaRuntime ) {
1017                         $this->mTrxWriteAdjDuration += $runtime;
1018                         $this->mTrxWriteAdjQueryCount += 1;
1019                 }
1020         }
1021
1022         private function canRecoverFromDisconnect( $sql, $priorWritesPending ) {
1023                 # Transaction dropped; this can mean lost writes, or REPEATABLE-READ snapshots.
1024                 # Dropped connections also mean that named locks are automatically released.
1025                 # Only allow error suppression in autocommit mode or when the lost transaction
1026                 # didn't matter anyway (aside from DBO_TRX snapshot loss).
1027                 if ( $this->mNamedLocksHeld ) {
1028                         return false; // possible critical section violation
1029                 } elseif ( $sql === 'COMMIT' ) {
1030                         return !$priorWritesPending; // nothing written anyway? (T127428)
1031                 } elseif ( $sql === 'ROLLBACK' ) {
1032                         return true; // transaction lost...which is also what was requested :)
1033                 } elseif ( $this->explicitTrxActive() ) {
1034                         return false; // don't drop atomocity
1035                 } elseif ( $priorWritesPending ) {
1036                         return false; // prior writes lost from implicit transaction
1037                 }
1038
1039                 return true;
1040         }
1041
1042         private function handleSessionLoss() {
1043                 $this->mTrxLevel = 0;
1044                 $this->mTrxIdleCallbacks = []; // T67263
1045                 $this->mTrxPreCommitCallbacks = []; // T67263
1046                 $this->mSessionTempTables = [];
1047                 $this->mNamedLocksHeld = [];
1048                 try {
1049                         // Handle callbacks in mTrxEndCallbacks
1050                         $this->runOnTransactionIdleCallbacks( self::TRIGGER_ROLLBACK );
1051                         $this->runTransactionListenerCallbacks( self::TRIGGER_ROLLBACK );
1052                         return null;
1053                 } catch ( Exception $e ) {
1054                         // Already logged; move on...
1055                         return $e;
1056                 }
1057         }
1058
1059         public function reportQueryError( $error, $errno, $sql, $fname, $tempIgnore = false ) {
1060                 if ( $this->ignoreErrors() || $tempIgnore ) {
1061                         $this->queryLogger->debug( "SQL ERROR (ignored): $error\n" );
1062                 } else {
1063                         $sql1line = mb_substr( str_replace( "\n", "\\n", $sql ), 0, 5 * 1024 );
1064                         $this->queryLogger->error(
1065                                 "{fname}\t{db_server}\t{errno}\t{error}\t{sql1line}",
1066                                 $this->getLogContext( [
1067                                         'method' => __METHOD__,
1068                                         'errno' => $errno,
1069                                         'error' => $error,
1070                                         'sql1line' => $sql1line,
1071                                         'fname' => $fname,
1072                                 ] )
1073                         );
1074                         $this->queryLogger->debug( "SQL ERROR: " . $error . "\n" );
1075                         throw new DBQueryError( $this, $error, $errno, $sql, $fname );
1076                 }
1077         }
1078
1079         public function freeResult( $res ) {
1080         }
1081
1082         public function selectField(
1083                 $table, $var, $cond = '', $fname = __METHOD__, $options = []
1084         ) {
1085                 if ( $var === '*' ) { // sanity
1086                         throw new DBUnexpectedError( $this, "Cannot use a * field: got '$var'" );
1087                 }
1088
1089                 if ( !is_array( $options ) ) {
1090                         $options = [ $options ];
1091                 }
1092
1093                 $options['LIMIT'] = 1;
1094
1095                 $res = $this->select( $table, $var, $cond, $fname, $options );
1096                 if ( $res === false || !$this->numRows( $res ) ) {
1097                         return false;
1098                 }
1099
1100                 $row = $this->fetchRow( $res );
1101
1102                 if ( $row !== false ) {
1103                         return reset( $row );
1104                 } else {
1105                         return false;
1106                 }
1107         }
1108
1109         public function selectFieldValues(
1110                 $table, $var, $cond = '', $fname = __METHOD__, $options = [], $join_conds = []
1111         ) {
1112                 if ( $var === '*' ) { // sanity
1113                         throw new DBUnexpectedError( $this, "Cannot use a * field" );
1114                 } elseif ( !is_string( $var ) ) { // sanity
1115                         throw new DBUnexpectedError( $this, "Cannot use an array of fields" );
1116                 }
1117
1118                 if ( !is_array( $options ) ) {
1119                         $options = [ $options ];
1120                 }
1121
1122                 $res = $this->select( $table, $var, $cond, $fname, $options, $join_conds );
1123                 if ( $res === false ) {
1124                         return false;
1125                 }
1126
1127                 $values = [];
1128                 foreach ( $res as $row ) {
1129                         $values[] = $row->$var;
1130                 }
1131
1132                 return $values;
1133         }
1134
1135         /**
1136          * Returns an optional USE INDEX clause to go after the table, and a
1137          * string to go at the end of the query.
1138          *
1139          * @param array $options Associative array of options to be turned into
1140          *   an SQL query, valid keys are listed in the function.
1141          * @return array
1142          * @see Database::select()
1143          */
1144         protected function makeSelectOptions( $options ) {
1145                 $preLimitTail = $postLimitTail = '';
1146                 $startOpts = '';
1147
1148                 $noKeyOptions = [];
1149
1150                 foreach ( $options as $key => $option ) {
1151                         if ( is_numeric( $key ) ) {
1152                                 $noKeyOptions[$option] = true;
1153                         }
1154                 }
1155
1156                 $preLimitTail .= $this->makeGroupByWithHaving( $options );
1157
1158                 $preLimitTail .= $this->makeOrderBy( $options );
1159
1160                 if ( isset( $noKeyOptions['FOR UPDATE'] ) ) {
1161                         $postLimitTail .= ' FOR UPDATE';
1162                 }
1163
1164                 if ( isset( $noKeyOptions['LOCK IN SHARE MODE'] ) ) {
1165                         $postLimitTail .= ' LOCK IN SHARE MODE';
1166                 }
1167
1168                 if ( isset( $noKeyOptions['DISTINCT'] ) || isset( $noKeyOptions['DISTINCTROW'] ) ) {
1169                         $startOpts .= 'DISTINCT';
1170                 }
1171
1172                 # Various MySQL extensions
1173                 if ( isset( $noKeyOptions['STRAIGHT_JOIN'] ) ) {
1174                         $startOpts .= ' /*! STRAIGHT_JOIN */';
1175                 }
1176
1177                 if ( isset( $noKeyOptions['HIGH_PRIORITY'] ) ) {
1178                         $startOpts .= ' HIGH_PRIORITY';
1179                 }
1180
1181                 if ( isset( $noKeyOptions['SQL_BIG_RESULT'] ) ) {
1182                         $startOpts .= ' SQL_BIG_RESULT';
1183                 }
1184
1185                 if ( isset( $noKeyOptions['SQL_BUFFER_RESULT'] ) ) {
1186                         $startOpts .= ' SQL_BUFFER_RESULT';
1187                 }
1188
1189                 if ( isset( $noKeyOptions['SQL_SMALL_RESULT'] ) ) {
1190                         $startOpts .= ' SQL_SMALL_RESULT';
1191                 }
1192
1193                 if ( isset( $noKeyOptions['SQL_CALC_FOUND_ROWS'] ) ) {
1194                         $startOpts .= ' SQL_CALC_FOUND_ROWS';
1195                 }
1196
1197                 if ( isset( $noKeyOptions['SQL_CACHE'] ) ) {
1198                         $startOpts .= ' SQL_CACHE';
1199                 }
1200
1201                 if ( isset( $noKeyOptions['SQL_NO_CACHE'] ) ) {
1202                         $startOpts .= ' SQL_NO_CACHE';
1203                 }
1204
1205                 if ( isset( $options['USE INDEX'] ) && is_string( $options['USE INDEX'] ) ) {
1206                         $useIndex = $this->useIndexClause( $options['USE INDEX'] );
1207                 } else {
1208                         $useIndex = '';
1209                 }
1210                 if ( isset( $options['IGNORE INDEX'] ) && is_string( $options['IGNORE INDEX'] ) ) {
1211                         $ignoreIndex = $this->ignoreIndexClause( $options['IGNORE INDEX'] );
1212                 } else {
1213                         $ignoreIndex = '';
1214                 }
1215
1216                 return [ $startOpts, $useIndex, $preLimitTail, $postLimitTail, $ignoreIndex ];
1217         }
1218
1219         /**
1220          * Returns an optional GROUP BY with an optional HAVING
1221          *
1222          * @param array $options Associative array of options
1223          * @return string
1224          * @see Database::select()
1225          * @since 1.21
1226          */
1227         protected function makeGroupByWithHaving( $options ) {
1228                 $sql = '';
1229                 if ( isset( $options['GROUP BY'] ) ) {
1230                         $gb = is_array( $options['GROUP BY'] )
1231                                 ? implode( ',', $options['GROUP BY'] )
1232                                 : $options['GROUP BY'];
1233                         $sql .= ' GROUP BY ' . $gb;
1234                 }
1235                 if ( isset( $options['HAVING'] ) ) {
1236                         $having = is_array( $options['HAVING'] )
1237                                 ? $this->makeList( $options['HAVING'], self::LIST_AND )
1238                                 : $options['HAVING'];
1239                         $sql .= ' HAVING ' . $having;
1240                 }
1241
1242                 return $sql;
1243         }
1244
1245         /**
1246          * Returns an optional ORDER BY
1247          *
1248          * @param array $options Associative array of options
1249          * @return string
1250          * @see Database::select()
1251          * @since 1.21
1252          */
1253         protected function makeOrderBy( $options ) {
1254                 if ( isset( $options['ORDER BY'] ) ) {
1255                         $ob = is_array( $options['ORDER BY'] )
1256                                 ? implode( ',', $options['ORDER BY'] )
1257                                 : $options['ORDER BY'];
1258
1259                         return ' ORDER BY ' . $ob;
1260                 }
1261
1262                 return '';
1263         }
1264
1265         public function select( $table, $vars, $conds = '', $fname = __METHOD__,
1266                 $options = [], $join_conds = [] ) {
1267                 $sql = $this->selectSQLText( $table, $vars, $conds, $fname, $options, $join_conds );
1268
1269                 return $this->query( $sql, $fname );
1270         }
1271
1272         public function selectSQLText( $table, $vars, $conds = '', $fname = __METHOD__,
1273                 $options = [], $join_conds = []
1274         ) {
1275                 if ( is_array( $vars ) ) {
1276                         $vars = implode( ',', $this->fieldNamesWithAlias( $vars ) );
1277                 }
1278
1279                 $options = (array)$options;
1280                 $useIndexes = ( isset( $options['USE INDEX'] ) && is_array( $options['USE INDEX'] ) )
1281                         ? $options['USE INDEX']
1282                         : [];
1283                 $ignoreIndexes = (
1284                         isset( $options['IGNORE INDEX'] ) &&
1285                         is_array( $options['IGNORE INDEX'] )
1286                 )
1287                         ? $options['IGNORE INDEX']
1288                         : [];
1289
1290                 if ( is_array( $table ) ) {
1291                         $from = ' FROM ' .
1292                                 $this->tableNamesWithIndexClauseOrJOIN(
1293                                         $table, $useIndexes, $ignoreIndexes, $join_conds );
1294                 } elseif ( $table != '' ) {
1295                         if ( $table[0] == ' ' ) {
1296                                 $from = ' FROM ' . $table;
1297                         } else {
1298                                 $from = ' FROM ' .
1299                                         $this->tableNamesWithIndexClauseOrJOIN(
1300                                                 [ $table ], $useIndexes, $ignoreIndexes, [] );
1301                         }
1302                 } else {
1303                         $from = '';
1304                 }
1305
1306                 list( $startOpts, $useIndex, $preLimitTail, $postLimitTail, $ignoreIndex ) =
1307                         $this->makeSelectOptions( $options );
1308
1309                 if ( !empty( $conds ) ) {
1310                         if ( is_array( $conds ) ) {
1311                                 $conds = $this->makeList( $conds, self::LIST_AND );
1312                         }
1313                         $sql = "SELECT $startOpts $vars $from $useIndex $ignoreIndex " .
1314                                 "WHERE $conds $preLimitTail";
1315                 } else {
1316                         $sql = "SELECT $startOpts $vars $from $useIndex $ignoreIndex $preLimitTail";
1317                 }
1318
1319                 if ( isset( $options['LIMIT'] ) ) {
1320                         $sql = $this->limitResult( $sql, $options['LIMIT'],
1321                                 isset( $options['OFFSET'] ) ? $options['OFFSET'] : false );
1322                 }
1323                 $sql = "$sql $postLimitTail";
1324
1325                 if ( isset( $options['EXPLAIN'] ) ) {
1326                         $sql = 'EXPLAIN ' . $sql;
1327                 }
1328
1329                 return $sql;
1330         }
1331
1332         public function selectRow( $table, $vars, $conds, $fname = __METHOD__,
1333                 $options = [], $join_conds = []
1334         ) {
1335                 $options = (array)$options;
1336                 $options['LIMIT'] = 1;
1337                 $res = $this->select( $table, $vars, $conds, $fname, $options, $join_conds );
1338
1339                 if ( $res === false ) {
1340                         return false;
1341                 }
1342
1343                 if ( !$this->numRows( $res ) ) {
1344                         return false;
1345                 }
1346
1347                 $obj = $this->fetchObject( $res );
1348
1349                 return $obj;
1350         }
1351
1352         public function estimateRowCount(
1353                 $table, $vars = '*', $conds = '', $fname = __METHOD__, $options = []
1354         ) {
1355                 $rows = 0;
1356                 $res = $this->select( $table, [ 'rowcount' => 'COUNT(*)' ], $conds, $fname, $options );
1357
1358                 if ( $res ) {
1359                         $row = $this->fetchRow( $res );
1360                         $rows = ( isset( $row['rowcount'] ) ) ? (int)$row['rowcount'] : 0;
1361                 }
1362
1363                 return $rows;
1364         }
1365
1366         public function selectRowCount(
1367                 $tables, $vars = '*', $conds = '', $fname = __METHOD__, $options = [], $join_conds = []
1368         ) {
1369                 $rows = 0;
1370                 $sql = $this->selectSQLText( $tables, '1', $conds, $fname, $options, $join_conds );
1371                 // The identifier quotes is primarily for MSSQL.
1372                 $rowCountCol = $this->addIdentifierQuotes( "rowcount" );
1373                 $tableName = $this->addIdentifierQuotes( "tmp_count" );
1374                 $res = $this->query( "SELECT COUNT(*) AS $rowCountCol FROM ($sql) $tableName", $fname );
1375
1376                 if ( $res ) {
1377                         $row = $this->fetchRow( $res );
1378                         $rows = ( isset( $row['rowcount'] ) ) ? (int)$row['rowcount'] : 0;
1379                 }
1380
1381                 return $rows;
1382         }
1383
1384         /**
1385          * Removes most variables from an SQL query and replaces them with X or N for numbers.
1386          * It's only slightly flawed. Don't use for anything important.
1387          *
1388          * @param string $sql A SQL Query
1389          *
1390          * @return string
1391          */
1392         protected static function generalizeSQL( $sql ) {
1393                 # This does the same as the regexp below would do, but in such a way
1394                 # as to avoid crashing php on some large strings.
1395                 # $sql = preg_replace( "/'([^\\\\']|\\\\.)*'|\"([^\\\\\"]|\\\\.)*\"/", "'X'", $sql );
1396
1397                 $sql = str_replace( "\\\\", '', $sql );
1398                 $sql = str_replace( "\\'", '', $sql );
1399                 $sql = str_replace( "\\\"", '', $sql );
1400                 $sql = preg_replace( "/'.*'/s", "'X'", $sql );
1401                 $sql = preg_replace( '/".*"/s', "'X'", $sql );
1402
1403                 # All newlines, tabs, etc replaced by single space
1404                 $sql = preg_replace( '/\s+/', ' ', $sql );
1405
1406                 # All numbers => N,
1407                 # except the ones surrounded by characters, e.g. l10n
1408                 $sql = preg_replace( '/-?\d+(,-?\d+)+/s', 'N,...,N', $sql );
1409                 $sql = preg_replace( '/(?<![a-zA-Z])-?\d+(?![a-zA-Z])/s', 'N', $sql );
1410
1411                 return $sql;
1412         }
1413
1414         public function fieldExists( $table, $field, $fname = __METHOD__ ) {
1415                 $info = $this->fieldInfo( $table, $field );
1416
1417                 return (bool)$info;
1418         }
1419
1420         public function indexExists( $table, $index, $fname = __METHOD__ ) {
1421                 if ( !$this->tableExists( $table ) ) {
1422                         return null;
1423                 }
1424
1425                 $info = $this->indexInfo( $table, $index, $fname );
1426                 if ( is_null( $info ) ) {
1427                         return null;
1428                 } else {
1429                         return $info !== false;
1430                 }
1431         }
1432
1433         public function tableExists( $table, $fname = __METHOD__ ) {
1434                 $tableRaw = $this->tableName( $table, 'raw' );
1435                 if ( isset( $this->mSessionTempTables[$tableRaw] ) ) {
1436                         return true; // already known to exist
1437                 }
1438
1439                 $table = $this->tableName( $table );
1440                 $ignoreErrors = true;
1441                 $res = $this->query( "SELECT 1 FROM $table LIMIT 1", $fname, $ignoreErrors );
1442
1443                 return (bool)$res;
1444         }
1445
1446         public function indexUnique( $table, $index ) {
1447                 $indexInfo = $this->indexInfo( $table, $index );
1448
1449                 if ( !$indexInfo ) {
1450                         return null;
1451                 }
1452
1453                 return !$indexInfo[0]->Non_unique;
1454         }
1455
1456         /**
1457          * Helper for Database::insert().
1458          *
1459          * @param array $options
1460          * @return string
1461          */
1462         protected function makeInsertOptions( $options ) {
1463                 return implode( ' ', $options );
1464         }
1465
1466         public function insert( $table, $a, $fname = __METHOD__, $options = [] ) {
1467                 # No rows to insert, easy just return now
1468                 if ( !count( $a ) ) {
1469                         return true;
1470                 }
1471
1472                 $table = $this->tableName( $table );
1473
1474                 if ( !is_array( $options ) ) {
1475                         $options = [ $options ];
1476                 }
1477
1478                 $fh = null;
1479                 if ( isset( $options['fileHandle'] ) ) {
1480                         $fh = $options['fileHandle'];
1481                 }
1482                 $options = $this->makeInsertOptions( $options );
1483
1484                 if ( isset( $a[0] ) && is_array( $a[0] ) ) {
1485                         $multi = true;
1486                         $keys = array_keys( $a[0] );
1487                 } else {
1488                         $multi = false;
1489                         $keys = array_keys( $a );
1490                 }
1491
1492                 $sql = 'INSERT ' . $options .
1493                         " INTO $table (" . implode( ',', $keys ) . ') VALUES ';
1494
1495                 if ( $multi ) {
1496                         $first = true;
1497                         foreach ( $a as $row ) {
1498                                 if ( $first ) {
1499                                         $first = false;
1500                                 } else {
1501                                         $sql .= ',';
1502                                 }
1503                                 $sql .= '(' . $this->makeList( $row ) . ')';
1504                         }
1505                 } else {
1506                         $sql .= '(' . $this->makeList( $a ) . ')';
1507                 }
1508
1509                 if ( $fh !== null && false === fwrite( $fh, $sql ) ) {
1510                         return false;
1511                 } elseif ( $fh !== null ) {
1512                         return true;
1513                 }
1514
1515                 return (bool)$this->query( $sql, $fname );
1516         }
1517
1518         /**
1519          * Make UPDATE options array for Database::makeUpdateOptions
1520          *
1521          * @param array $options
1522          * @return array
1523          */
1524         protected function makeUpdateOptionsArray( $options ) {
1525                 if ( !is_array( $options ) ) {
1526                         $options = [ $options ];
1527                 }
1528
1529                 $opts = [];
1530
1531                 if ( in_array( 'IGNORE', $options ) ) {
1532                         $opts[] = 'IGNORE';
1533                 }
1534
1535                 return $opts;
1536         }
1537
1538         /**
1539          * Make UPDATE options for the Database::update function
1540          *
1541          * @param array $options The options passed to Database::update
1542          * @return string
1543          */
1544         protected function makeUpdateOptions( $options ) {
1545                 $opts = $this->makeUpdateOptionsArray( $options );
1546
1547                 return implode( ' ', $opts );
1548         }
1549
1550         public function update( $table, $values, $conds, $fname = __METHOD__, $options = [] ) {
1551                 $table = $this->tableName( $table );
1552                 $opts = $this->makeUpdateOptions( $options );
1553                 $sql = "UPDATE $opts $table SET " . $this->makeList( $values, self::LIST_SET );
1554
1555                 if ( $conds !== [] && $conds !== '*' ) {
1556                         $sql .= " WHERE " . $this->makeList( $conds, self::LIST_AND );
1557                 }
1558
1559                 return (bool)$this->query( $sql, $fname );
1560         }
1561
1562         public function makeList( $a, $mode = self::LIST_COMMA ) {
1563                 if ( !is_array( $a ) ) {
1564                         throw new DBUnexpectedError( $this, __METHOD__ . ' called with incorrect parameters' );
1565                 }
1566
1567                 $first = true;
1568                 $list = '';
1569
1570                 foreach ( $a as $field => $value ) {
1571                         if ( !$first ) {
1572                                 if ( $mode == self::LIST_AND ) {
1573                                         $list .= ' AND ';
1574                                 } elseif ( $mode == self::LIST_OR ) {
1575                                         $list .= ' OR ';
1576                                 } else {
1577                                         $list .= ',';
1578                                 }
1579                         } else {
1580                                 $first = false;
1581                         }
1582
1583                         if ( ( $mode == self::LIST_AND || $mode == self::LIST_OR ) && is_numeric( $field ) ) {
1584                                 $list .= "($value)";
1585                         } elseif ( $mode == self::LIST_SET && is_numeric( $field ) ) {
1586                                 $list .= "$value";
1587                         } elseif (
1588                                 ( $mode == self::LIST_AND || $mode == self::LIST_OR ) && is_array( $value )
1589                         ) {
1590                                 // Remove null from array to be handled separately if found
1591                                 $includeNull = false;
1592                                 foreach ( array_keys( $value, null, true ) as $nullKey ) {
1593                                         $includeNull = true;
1594                                         unset( $value[$nullKey] );
1595                                 }
1596                                 if ( count( $value ) == 0 && !$includeNull ) {
1597                                         throw new InvalidArgumentException(
1598                                                 __METHOD__ . ": empty input for field $field" );
1599                                 } elseif ( count( $value ) == 0 ) {
1600                                         // only check if $field is null
1601                                         $list .= "$field IS NULL";
1602                                 } else {
1603                                         // IN clause contains at least one valid element
1604                                         if ( $includeNull ) {
1605                                                 // Group subconditions to ensure correct precedence
1606                                                 $list .= '(';
1607                                         }
1608                                         if ( count( $value ) == 1 ) {
1609                                                 // Special-case single values, as IN isn't terribly efficient
1610                                                 // Don't necessarily assume the single key is 0; we don't
1611                                                 // enforce linear numeric ordering on other arrays here.
1612                                                 $value = array_values( $value )[0];
1613                                                 $list .= $field . " = " . $this->addQuotes( $value );
1614                                         } else {
1615                                                 $list .= $field . " IN (" . $this->makeList( $value ) . ") ";
1616                                         }
1617                                         // if null present in array, append IS NULL
1618                                         if ( $includeNull ) {
1619                                                 $list .= " OR $field IS NULL)";
1620                                         }
1621                                 }
1622                         } elseif ( $value === null ) {
1623                                 if ( $mode == self::LIST_AND || $mode == self::LIST_OR ) {
1624                                         $list .= "$field IS ";
1625                                 } elseif ( $mode == self::LIST_SET ) {
1626                                         $list .= "$field = ";
1627                                 }
1628                                 $list .= 'NULL';
1629                         } else {
1630                                 if (
1631                                         $mode == self::LIST_AND || $mode == self::LIST_OR || $mode == self::LIST_SET
1632                                 ) {
1633                                         $list .= "$field = ";
1634                                 }
1635                                 $list .= $mode == self::LIST_NAMES ? $value : $this->addQuotes( $value );
1636                         }
1637                 }
1638
1639                 return $list;
1640         }
1641
1642         public function makeWhereFrom2d( $data, $baseKey, $subKey ) {
1643                 $conds = [];
1644
1645                 foreach ( $data as $base => $sub ) {
1646                         if ( count( $sub ) ) {
1647                                 $conds[] = $this->makeList(
1648                                         [ $baseKey => $base, $subKey => array_keys( $sub ) ],
1649                                         self::LIST_AND );
1650                         }
1651                 }
1652
1653                 if ( $conds ) {
1654                         return $this->makeList( $conds, self::LIST_OR );
1655                 } else {
1656                         // Nothing to search for...
1657                         return false;
1658                 }
1659         }
1660
1661         public function aggregateValue( $valuedata, $valuename = 'value' ) {
1662                 return $valuename;
1663         }
1664
1665         public function bitNot( $field ) {
1666                 return "(~$field)";
1667         }
1668
1669         public function bitAnd( $fieldLeft, $fieldRight ) {
1670                 return "($fieldLeft & $fieldRight)";
1671         }
1672
1673         public function bitOr( $fieldLeft, $fieldRight ) {
1674                 return "($fieldLeft | $fieldRight)";
1675         }
1676
1677         public function buildConcat( $stringList ) {
1678                 return 'CONCAT(' . implode( ',', $stringList ) . ')';
1679         }
1680
1681         public function buildGroupConcatField(
1682                 $delim, $table, $field, $conds = '', $join_conds = []
1683         ) {
1684                 $fld = "GROUP_CONCAT($field SEPARATOR " . $this->addQuotes( $delim ) . ')';
1685
1686                 return '(' . $this->selectSQLText( $table, $fld, $conds, null, [], $join_conds ) . ')';
1687         }
1688
1689         public function buildStringCast( $field ) {
1690                 return $field;
1691         }
1692
1693         public function selectDB( $db ) {
1694                 # Stub. Shouldn't cause serious problems if it's not overridden, but
1695                 # if your database engine supports a concept similar to MySQL's
1696                 # databases you may as well.
1697                 $this->mDBname = $db;
1698
1699                 return true;
1700         }
1701
1702         public function getDBname() {
1703                 return $this->mDBname;
1704         }
1705
1706         public function getServer() {
1707                 return $this->mServer;
1708         }
1709
1710         public function tableName( $name, $format = 'quoted' ) {
1711                 # Skip the entire process when we have a string quoted on both ends.
1712                 # Note that we check the end so that we will still quote any use of
1713                 # use of `database`.table. But won't break things if someone wants
1714                 # to query a database table with a dot in the name.
1715                 if ( $this->isQuotedIdentifier( $name ) ) {
1716                         return $name;
1717                 }
1718
1719                 # Lets test for any bits of text that should never show up in a table
1720                 # name. Basically anything like JOIN or ON which are actually part of
1721                 # SQL queries, but may end up inside of the table value to combine
1722                 # sql. Such as how the API is doing.
1723                 # Note that we use a whitespace test rather than a \b test to avoid
1724                 # any remote case where a word like on may be inside of a table name
1725                 # surrounded by symbols which may be considered word breaks.
1726                 if ( preg_match( '/(^|\s)(DISTINCT|JOIN|ON|AS)(\s|$)/i', $name ) !== 0 ) {
1727                         return $name;
1728                 }
1729
1730                 # Split database and table into proper variables.
1731                 # We reverse the explode so that database.table and table both output
1732                 # the correct table.
1733                 $dbDetails = explode( '.', $name, 3 );
1734                 if ( count( $dbDetails ) == 3 ) {
1735                         list( $database, $schema, $table ) = $dbDetails;
1736                         # We don't want any prefix added in this case
1737                         $prefix = '';
1738                 } elseif ( count( $dbDetails ) == 2 ) {
1739                         list( $database, $table ) = $dbDetails;
1740                         # We don't want any prefix added in this case
1741                         $prefix = '';
1742                         # In dbs that support it, $database may actually be the schema
1743                         # but that doesn't affect any of the functionality here
1744                         $schema = '';
1745                 } else {
1746                         list( $table ) = $dbDetails;
1747                         if ( isset( $this->tableAliases[$table] ) ) {
1748                                 $database = $this->tableAliases[$table]['dbname'];
1749                                 $schema = is_string( $this->tableAliases[$table]['schema'] )
1750                                         ? $this->tableAliases[$table]['schema']
1751                                         : $this->mSchema;
1752                                 $prefix = is_string( $this->tableAliases[$table]['prefix'] )
1753                                         ? $this->tableAliases[$table]['prefix']
1754                                         : $this->mTablePrefix;
1755                         } else {
1756                                 $database = '';
1757                                 $schema = $this->mSchema; # Default schema
1758                                 $prefix = $this->mTablePrefix; # Default prefix
1759                         }
1760                 }
1761
1762                 # Quote $table and apply the prefix if not quoted.
1763                 # $tableName might be empty if this is called from Database::replaceVars()
1764                 $tableName = "{$prefix}{$table}";
1765                 if ( $format === 'quoted'
1766                         && !$this->isQuotedIdentifier( $tableName )
1767                         && $tableName !== ''
1768                 ) {
1769                         $tableName = $this->addIdentifierQuotes( $tableName );
1770                 }
1771
1772                 # Quote $schema and $database and merge them with the table name if needed
1773                 $tableName = $this->prependDatabaseOrSchema( $schema, $tableName, $format );
1774                 $tableName = $this->prependDatabaseOrSchema( $database, $tableName, $format );
1775
1776                 return $tableName;
1777         }
1778
1779         /**
1780          * @param string|null $namespace Database or schema
1781          * @param string $relation Name of table, view, sequence, etc...
1782          * @param string $format One of (raw, quoted)
1783          * @return string Relation name with quoted and merged $namespace as needed
1784          */
1785         private function prependDatabaseOrSchema( $namespace, $relation, $format ) {
1786                 if ( strlen( $namespace ) ) {
1787                         if ( $format === 'quoted' && !$this->isQuotedIdentifier( $namespace ) ) {
1788                                 $namespace = $this->addIdentifierQuotes( $namespace );
1789                         }
1790                         $relation = $namespace . '.' . $relation;
1791                 }
1792
1793                 return $relation;
1794         }
1795
1796         public function tableNames() {
1797                 $inArray = func_get_args();
1798                 $retVal = [];
1799
1800                 foreach ( $inArray as $name ) {
1801                         $retVal[$name] = $this->tableName( $name );
1802                 }
1803
1804                 return $retVal;
1805         }
1806
1807         public function tableNamesN() {
1808                 $inArray = func_get_args();
1809                 $retVal = [];
1810
1811                 foreach ( $inArray as $name ) {
1812                         $retVal[] = $this->tableName( $name );
1813                 }
1814
1815                 return $retVal;
1816         }
1817
1818         /**
1819          * Get an aliased table name
1820          * e.g. tableName AS newTableName
1821          *
1822          * @param string $name Table name, see tableName()
1823          * @param string|bool $alias Alias (optional)
1824          * @return string SQL name for aliased table. Will not alias a table to its own name
1825          */
1826         protected function tableNameWithAlias( $name, $alias = false ) {
1827                 if ( !$alias || $alias == $name ) {
1828                         return $this->tableName( $name );
1829                 } else {
1830                         return $this->tableName( $name ) . ' ' . $this->addIdentifierQuotes( $alias );
1831                 }
1832         }
1833
1834         /**
1835          * Gets an array of aliased table names
1836          *
1837          * @param array $tables [ [alias] => table ]
1838          * @return string[] See tableNameWithAlias()
1839          */
1840         protected function tableNamesWithAlias( $tables ) {
1841                 $retval = [];
1842                 foreach ( $tables as $alias => $table ) {
1843                         if ( is_numeric( $alias ) ) {
1844                                 $alias = $table;
1845                         }
1846                         $retval[] = $this->tableNameWithAlias( $table, $alias );
1847                 }
1848
1849                 return $retval;
1850         }
1851
1852         /**
1853          * Get an aliased field name
1854          * e.g. fieldName AS newFieldName
1855          *
1856          * @param string $name Field name
1857          * @param string|bool $alias Alias (optional)
1858          * @return string SQL name for aliased field. Will not alias a field to its own name
1859          */
1860         protected function fieldNameWithAlias( $name, $alias = false ) {
1861                 if ( !$alias || (string)$alias === (string)$name ) {
1862                         return $name;
1863                 } else {
1864                         return $name . ' AS ' . $this->addIdentifierQuotes( $alias ); // PostgreSQL needs AS
1865                 }
1866         }
1867
1868         /**
1869          * Gets an array of aliased field names
1870          *
1871          * @param array $fields [ [alias] => field ]
1872          * @return string[] See fieldNameWithAlias()
1873          */
1874         protected function fieldNamesWithAlias( $fields ) {
1875                 $retval = [];
1876                 foreach ( $fields as $alias => $field ) {
1877                         if ( is_numeric( $alias ) ) {
1878                                 $alias = $field;
1879                         }
1880                         $retval[] = $this->fieldNameWithAlias( $field, $alias );
1881                 }
1882
1883                 return $retval;
1884         }
1885
1886         /**
1887          * Get the aliased table name clause for a FROM clause
1888          * which might have a JOIN and/or USE INDEX or IGNORE INDEX clause
1889          *
1890          * @param array $tables ( [alias] => table )
1891          * @param array $use_index Same as for select()
1892          * @param array $ignore_index Same as for select()
1893          * @param array $join_conds Same as for select()
1894          * @return string
1895          */
1896         protected function tableNamesWithIndexClauseOrJOIN(
1897                 $tables, $use_index = [], $ignore_index = [], $join_conds = []
1898         ) {
1899                 $ret = [];
1900                 $retJOIN = [];
1901                 $use_index = (array)$use_index;
1902                 $ignore_index = (array)$ignore_index;
1903                 $join_conds = (array)$join_conds;
1904
1905                 foreach ( $tables as $alias => $table ) {
1906                         if ( !is_string( $alias ) ) {
1907                                 // No alias? Set it equal to the table name
1908                                 $alias = $table;
1909                         }
1910                         // Is there a JOIN clause for this table?
1911                         if ( isset( $join_conds[$alias] ) ) {
1912                                 list( $joinType, $conds ) = $join_conds[$alias];
1913                                 $tableClause = $joinType;
1914                                 $tableClause .= ' ' . $this->tableNameWithAlias( $table, $alias );
1915                                 if ( isset( $use_index[$alias] ) ) { // has USE INDEX?
1916                                         $use = $this->useIndexClause( implode( ',', (array)$use_index[$alias] ) );
1917                                         if ( $use != '' ) {
1918                                                 $tableClause .= ' ' . $use;
1919                                         }
1920                                 }
1921                                 if ( isset( $ignore_index[$alias] ) ) { // has IGNORE INDEX?
1922                                         $ignore = $this->ignoreIndexClause(
1923                                                 implode( ',', (array)$ignore_index[$alias] ) );
1924                                         if ( $ignore != '' ) {
1925                                                 $tableClause .= ' ' . $ignore;
1926                                         }
1927                                 }
1928                                 $on = $this->makeList( (array)$conds, self::LIST_AND );
1929                                 if ( $on != '' ) {
1930                                         $tableClause .= ' ON (' . $on . ')';
1931                                 }
1932
1933                                 $retJOIN[] = $tableClause;
1934                         } elseif ( isset( $use_index[$alias] ) ) {
1935                                 // Is there an INDEX clause for this table?
1936                                 $tableClause = $this->tableNameWithAlias( $table, $alias );
1937                                 $tableClause .= ' ' . $this->useIndexClause(
1938                                                 implode( ',', (array)$use_index[$alias] )
1939                                         );
1940
1941                                 $ret[] = $tableClause;
1942                         } elseif ( isset( $ignore_index[$alias] ) ) {
1943                                 // Is there an INDEX clause for this table?
1944                                 $tableClause = $this->tableNameWithAlias( $table, $alias );
1945                                 $tableClause .= ' ' . $this->ignoreIndexClause(
1946                                                 implode( ',', (array)$ignore_index[$alias] )
1947                                         );
1948
1949                                 $ret[] = $tableClause;
1950                         } else {
1951                                 $tableClause = $this->tableNameWithAlias( $table, $alias );
1952
1953                                 $ret[] = $tableClause;
1954                         }
1955                 }
1956
1957                 // We can't separate explicit JOIN clauses with ',', use ' ' for those
1958                 $implicitJoins = !empty( $ret ) ? implode( ',', $ret ) : "";
1959                 $explicitJoins = !empty( $retJOIN ) ? implode( ' ', $retJOIN ) : "";
1960
1961                 // Compile our final table clause
1962                 return implode( ' ', [ $implicitJoins, $explicitJoins ] );
1963         }
1964
1965         /**
1966          * Allows for index remapping in queries where this is not consistent across DBMS
1967          *
1968          * @param string $index
1969          * @return string
1970          */
1971         protected function indexName( $index ) {
1972                 return $index;
1973         }
1974
1975         public function addQuotes( $s ) {
1976                 if ( $s instanceof Blob ) {
1977                         $s = $s->fetch();
1978                 }
1979                 if ( $s === null ) {
1980                         return 'NULL';
1981                 } elseif ( is_bool( $s ) ) {
1982                         return (int)$s;
1983                 } else {
1984                         # This will also quote numeric values. This should be harmless,
1985                         # and protects against weird problems that occur when they really
1986                         # _are_ strings such as article titles and string->number->string
1987                         # conversion is not 1:1.
1988                         return "'" . $this->strencode( $s ) . "'";
1989                 }
1990         }
1991
1992         /**
1993          * Quotes an identifier using `backticks` or "double quotes" depending on the database type.
1994          * MySQL uses `backticks` while basically everything else uses double quotes.
1995          * Since MySQL is the odd one out here the double quotes are our generic
1996          * and we implement backticks in DatabaseMysql.
1997          *
1998          * @param string $s
1999          * @return string
2000          */
2001         public function addIdentifierQuotes( $s ) {
2002                 return '"' . str_replace( '"', '""', $s ) . '"';
2003         }
2004
2005         /**
2006          * Returns if the given identifier looks quoted or not according to
2007          * the database convention for quoting identifiers .
2008          *
2009          * @note Do not use this to determine if untrusted input is safe.
2010          *   A malicious user can trick this function.
2011          * @param string $name
2012          * @return bool
2013          */
2014         public function isQuotedIdentifier( $name ) {
2015                 return $name[0] == '"' && substr( $name, -1, 1 ) == '"';
2016         }
2017
2018         /**
2019          * @param string $s
2020          * @return string
2021          */
2022         protected function escapeLikeInternal( $s, $escapeChar = '`' ) {
2023                 return str_replace( [ $escapeChar, '%', '_' ],
2024                         [ "{$escapeChar}{$escapeChar}", "{$escapeChar}%", "{$escapeChar}_" ],
2025                         $s );
2026         }
2027
2028         public function buildLike() {
2029                 $params = func_get_args();
2030
2031                 if ( count( $params ) > 0 && is_array( $params[0] ) ) {
2032                         $params = $params[0];
2033                 }
2034
2035                 $s = '';
2036
2037                 // We use ` instead of \ as the default LIKE escape character, since addQuotes()
2038                 // may escape backslashes, creating problems of double escaping. The `
2039                 // character has good cross-DBMS compatibility, avoiding special operators
2040                 // in MS SQL like ^ and %
2041                 $escapeChar = '`';
2042
2043                 foreach ( $params as $value ) {
2044                         if ( $value instanceof LikeMatch ) {
2045                                 $s .= $value->toString();
2046                         } else {
2047                                 $s .= $this->escapeLikeInternal( $value, $escapeChar );
2048                         }
2049                 }
2050
2051                 return ' LIKE ' . $this->addQuotes( $s ) . ' ESCAPE ' . $this->addQuotes( $escapeChar ) . ' ';
2052         }
2053
2054         public function anyChar() {
2055                 return new LikeMatch( '_' );
2056         }
2057
2058         public function anyString() {
2059                 return new LikeMatch( '%' );
2060         }
2061
2062         public function nextSequenceValue( $seqName ) {
2063                 return null;
2064         }
2065
2066         /**
2067          * USE INDEX clause. Unlikely to be useful for anything but MySQL. This
2068          * is only needed because a) MySQL must be as efficient as possible due to
2069          * its use on Wikipedia, and b) MySQL 4.0 is kind of dumb sometimes about
2070          * which index to pick. Anyway, other databases might have different
2071          * indexes on a given table. So don't bother overriding this unless you're
2072          * MySQL.
2073          * @param string $index
2074          * @return string
2075          */
2076         public function useIndexClause( $index ) {
2077                 return '';
2078         }
2079
2080         /**
2081          * IGNORE INDEX clause. Unlikely to be useful for anything but MySQL. This
2082          * is only needed because a) MySQL must be as efficient as possible due to
2083          * its use on Wikipedia, and b) MySQL 4.0 is kind of dumb sometimes about
2084          * which index to pick. Anyway, other databases might have different
2085          * indexes on a given table. So don't bother overriding this unless you're
2086          * MySQL.
2087          * @param string $index
2088          * @return string
2089          */
2090         public function ignoreIndexClause( $index ) {
2091                 return '';
2092         }
2093
2094         public function replace( $table, $uniqueIndexes, $rows, $fname = __METHOD__ ) {
2095                 $quotedTable = $this->tableName( $table );
2096
2097                 if ( count( $rows ) == 0 ) {
2098                         return;
2099                 }
2100
2101                 # Single row case
2102                 if ( !is_array( reset( $rows ) ) ) {
2103                         $rows = [ $rows ];
2104                 }
2105
2106                 // @FXIME: this is not atomic, but a trx would break affectedRows()
2107                 foreach ( $rows as $row ) {
2108                         # Delete rows which collide
2109                         if ( $uniqueIndexes ) {
2110                                 $sql = "DELETE FROM $quotedTable WHERE ";
2111                                 $first = true;
2112                                 foreach ( $uniqueIndexes as $index ) {
2113                                         if ( $first ) {
2114                                                 $first = false;
2115                                                 $sql .= '( ';
2116                                         } else {
2117                                                 $sql .= ' ) OR ( ';
2118                                         }
2119                                         if ( is_array( $index ) ) {
2120                                                 $first2 = true;
2121                                                 foreach ( $index as $col ) {
2122                                                         if ( $first2 ) {
2123                                                                 $first2 = false;
2124                                                         } else {
2125                                                                 $sql .= ' AND ';
2126                                                         }
2127                                                         $sql .= $col . '=' . $this->addQuotes( $row[$col] );
2128                                                 }
2129                                         } else {
2130                                                 $sql .= $index . '=' . $this->addQuotes( $row[$index] );
2131                                         }
2132                                 }
2133                                 $sql .= ' )';
2134                                 $this->query( $sql, $fname );
2135                         }
2136
2137                         # Now insert the row
2138                         $this->insert( $table, $row, $fname );
2139                 }
2140         }
2141
2142         /**
2143          * REPLACE query wrapper for MySQL and SQLite, which have a native REPLACE
2144          * statement.
2145          *
2146          * @param string $table Table name
2147          * @param array|string $rows Row(s) to insert
2148          * @param string $fname Caller function name
2149          *
2150          * @return ResultWrapper
2151          */
2152         protected function nativeReplace( $table, $rows, $fname ) {
2153                 $table = $this->tableName( $table );
2154
2155                 # Single row case
2156                 if ( !is_array( reset( $rows ) ) ) {
2157                         $rows = [ $rows ];
2158                 }
2159
2160                 $sql = "REPLACE INTO $table (" . implode( ',', array_keys( $rows[0] ) ) . ') VALUES ';
2161                 $first = true;
2162
2163                 foreach ( $rows as $row ) {
2164                         if ( $first ) {
2165                                 $first = false;
2166                         } else {
2167                                 $sql .= ',';
2168                         }
2169
2170                         $sql .= '(' . $this->makeList( $row ) . ')';
2171                 }
2172
2173                 return $this->query( $sql, $fname );
2174         }
2175
2176         public function upsert( $table, array $rows, array $uniqueIndexes, array $set,
2177                 $fname = __METHOD__
2178         ) {
2179                 if ( !count( $rows ) ) {
2180                         return true; // nothing to do
2181                 }
2182
2183                 if ( !is_array( reset( $rows ) ) ) {
2184                         $rows = [ $rows ];
2185                 }
2186
2187                 if ( count( $uniqueIndexes ) ) {
2188                         $clauses = []; // list WHERE clauses that each identify a single row
2189                         foreach ( $rows as $row ) {
2190                                 foreach ( $uniqueIndexes as $index ) {
2191                                         $index = is_array( $index ) ? $index : [ $index ]; // columns
2192                                         $rowKey = []; // unique key to this row
2193                                         foreach ( $index as $column ) {
2194                                                 $rowKey[$column] = $row[$column];
2195                                         }
2196                                         $clauses[] = $this->makeList( $rowKey, self::LIST_AND );
2197                                 }
2198                         }
2199                         $where = [ $this->makeList( $clauses, self::LIST_OR ) ];
2200                 } else {
2201                         $where = false;
2202                 }
2203
2204                 $useTrx = !$this->mTrxLevel;
2205                 if ( $useTrx ) {
2206                         $this->begin( $fname, self::TRANSACTION_INTERNAL );
2207                 }
2208                 try {
2209                         # Update any existing conflicting row(s)
2210                         if ( $where !== false ) {
2211                                 $ok = $this->update( $table, $set, $where, $fname );
2212                         } else {
2213                                 $ok = true;
2214                         }
2215                         # Now insert any non-conflicting row(s)
2216                         $ok = $this->insert( $table, $rows, $fname, [ 'IGNORE' ] ) && $ok;
2217                 } catch ( Exception $e ) {
2218                         if ( $useTrx ) {
2219                                 $this->rollback( $fname, self::FLUSHING_INTERNAL );
2220                         }
2221                         throw $e;
2222                 }
2223                 if ( $useTrx ) {
2224                         $this->commit( $fname, self::FLUSHING_INTERNAL );
2225                 }
2226
2227                 return $ok;
2228         }
2229
2230         public function deleteJoin( $delTable, $joinTable, $delVar, $joinVar, $conds,
2231                 $fname = __METHOD__
2232         ) {
2233                 if ( !$conds ) {
2234                         throw new DBUnexpectedError( $this, __METHOD__ . ' called with empty $conds' );
2235                 }
2236
2237                 $delTable = $this->tableName( $delTable );
2238                 $joinTable = $this->tableName( $joinTable );
2239                 $sql = "DELETE FROM $delTable WHERE $delVar IN (SELECT $joinVar FROM $joinTable ";
2240                 if ( $conds != '*' ) {
2241                         $sql .= 'WHERE ' . $this->makeList( $conds, self::LIST_AND );
2242                 }
2243                 $sql .= ')';
2244
2245                 $this->query( $sql, $fname );
2246         }
2247
2248         public function textFieldSize( $table, $field ) {
2249                 $table = $this->tableName( $table );
2250                 $sql = "SHOW COLUMNS FROM $table LIKE \"$field\";";
2251                 $res = $this->query( $sql, __METHOD__ );
2252                 $row = $this->fetchObject( $res );
2253
2254                 $m = [];
2255
2256                 if ( preg_match( '/\((.*)\)/', $row->Type, $m ) ) {
2257                         $size = $m[1];
2258                 } else {
2259                         $size = -1;
2260                 }
2261
2262                 return $size;
2263         }
2264
2265         public function delete( $table, $conds, $fname = __METHOD__ ) {
2266                 if ( !$conds ) {
2267                         throw new DBUnexpectedError( $this, __METHOD__ . ' called with no conditions' );
2268                 }
2269
2270                 $table = $this->tableName( $table );
2271                 $sql = "DELETE FROM $table";
2272
2273                 if ( $conds != '*' ) {
2274                         if ( is_array( $conds ) ) {
2275                                 $conds = $this->makeList( $conds, self::LIST_AND );
2276                         }
2277                         $sql .= ' WHERE ' . $conds;
2278                 }
2279
2280                 return $this->query( $sql, $fname );
2281         }
2282
2283         public function insertSelect(
2284                 $destTable, $srcTable, $varMap, $conds,
2285                 $fname = __METHOD__, $insertOptions = [], $selectOptions = []
2286         ) {
2287                 if ( $this->cliMode ) {
2288                         // For massive migrations with downtime, we don't want to select everything
2289                         // into memory and OOM, so do all this native on the server side if possible.
2290                         return $this->nativeInsertSelect(
2291                                 $destTable,
2292                                 $srcTable,
2293                                 $varMap,
2294                                 $conds,
2295                                 $fname,
2296                                 $insertOptions,
2297                                 $selectOptions
2298                         );
2299                 }
2300
2301                 // For web requests, do a locking SELECT and then INSERT. This puts the SELECT burden
2302                 // on only the master (without needing row-based-replication). It also makes it easy to
2303                 // know how big the INSERT is going to be.
2304                 $fields = [];
2305                 foreach ( $varMap as $dstColumn => $sourceColumnOrSql ) {
2306                         $fields[] = $this->fieldNameWithAlias( $sourceColumnOrSql, $dstColumn );
2307                 }
2308                 $selectOptions[] = 'FOR UPDATE';
2309                 $res = $this->select( $srcTable, implode( ',', $fields ), $conds, $fname, $selectOptions );
2310                 if ( !$res ) {
2311                         return false;
2312                 }
2313
2314                 $rows = [];
2315                 foreach ( $res as $row ) {
2316                         $rows[] = (array)$row;
2317                 }
2318
2319                 return $this->insert( $destTable, $rows, $fname, $insertOptions );
2320         }
2321
2322         protected function nativeInsertSelect( $destTable, $srcTable, $varMap, $conds,
2323                 $fname = __METHOD__,
2324                 $insertOptions = [], $selectOptions = []
2325         ) {
2326                 $destTable = $this->tableName( $destTable );
2327
2328                 if ( !is_array( $insertOptions ) ) {
2329                         $insertOptions = [ $insertOptions ];
2330                 }
2331
2332                 $insertOptions = $this->makeInsertOptions( $insertOptions );
2333
2334                 if ( !is_array( $selectOptions ) ) {
2335                         $selectOptions = [ $selectOptions ];
2336                 }
2337
2338                 list( $startOpts, $useIndex, $tailOpts, $ignoreIndex ) = $this->makeSelectOptions(
2339                         $selectOptions );
2340
2341                 if ( is_array( $srcTable ) ) {
2342                         $srcTable = implode( ',', array_map( [ $this, 'tableName' ], $srcTable ) );
2343                 } else {
2344                         $srcTable = $this->tableName( $srcTable );
2345                 }
2346
2347                 $sql = "INSERT $insertOptions" .
2348                         " INTO $destTable (" . implode( ',', array_keys( $varMap ) ) . ')' .
2349                         " SELECT $startOpts " . implode( ',', $varMap ) .
2350                         " FROM $srcTable $useIndex $ignoreIndex ";
2351
2352                 if ( $conds != '*' ) {
2353                         if ( is_array( $conds ) ) {
2354                                 $conds = $this->makeList( $conds, self::LIST_AND );
2355                         }
2356                         $sql .= " WHERE $conds";
2357                 }
2358
2359                 $sql .= " $tailOpts";
2360
2361                 return $this->query( $sql, $fname );
2362         }
2363
2364         /**
2365          * Construct a LIMIT query with optional offset. This is used for query
2366          * pages. The SQL should be adjusted so that only the first $limit rows
2367          * are returned. If $offset is provided as well, then the first $offset
2368          * rows should be discarded, and the next $limit rows should be returned.
2369          * If the result of the query is not ordered, then the rows to be returned
2370          * are theoretically arbitrary.
2371          *
2372          * $sql is expected to be a SELECT, if that makes a difference.
2373          *
2374          * The version provided by default works in MySQL and SQLite. It will very
2375          * likely need to be overridden for most other DBMSes.
2376          *
2377          * @param string $sql SQL query we will append the limit too
2378          * @param int $limit The SQL limit
2379          * @param int|bool $offset The SQL offset (default false)
2380          * @throws DBUnexpectedError
2381          * @return string
2382          */
2383         public function limitResult( $sql, $limit, $offset = false ) {
2384                 if ( !is_numeric( $limit ) ) {
2385                         throw new DBUnexpectedError( $this,
2386                                 "Invalid non-numeric limit passed to limitResult()\n" );
2387                 }
2388
2389                 return "$sql LIMIT "
2390                 . ( ( is_numeric( $offset ) && $offset != 0 ) ? "{$offset}," : "" )
2391                 . "{$limit} ";
2392         }
2393
2394         public function unionSupportsOrderAndLimit() {
2395                 return true; // True for almost every DB supported
2396         }
2397
2398         public function unionQueries( $sqls, $all ) {
2399                 $glue = $all ? ') UNION ALL (' : ') UNION (';
2400
2401                 return '(' . implode( $glue, $sqls ) . ')';
2402         }
2403
2404         public function conditional( $cond, $trueVal, $falseVal ) {
2405                 if ( is_array( $cond ) ) {
2406                         $cond = $this->makeList( $cond, self::LIST_AND );
2407                 }
2408
2409                 return " (CASE WHEN $cond THEN $trueVal ELSE $falseVal END) ";
2410         }
2411
2412         public function strreplace( $orig, $old, $new ) {
2413                 return "REPLACE({$orig}, {$old}, {$new})";
2414         }
2415
2416         public function getServerUptime() {
2417                 return 0;
2418         }
2419
2420         public function wasDeadlock() {
2421                 return false;
2422         }
2423
2424         public function wasLockTimeout() {
2425                 return false;
2426         }
2427
2428         public function wasErrorReissuable() {
2429                 return false;
2430         }
2431
2432         public function wasReadOnlyError() {
2433                 return false;
2434         }
2435
2436         /**
2437          * Do not use this method outside of Database/DBError classes
2438          *
2439          * @param integer|string $errno
2440          * @return bool Whether the given query error was a connection drop
2441          */
2442         public function wasConnectionError( $errno ) {
2443                 return false;
2444         }
2445
2446         public function deadlockLoop() {
2447                 $args = func_get_args();
2448                 $function = array_shift( $args );
2449                 $tries = self::DEADLOCK_TRIES;
2450
2451                 $this->begin( __METHOD__ );
2452
2453                 $retVal = null;
2454                 /** @var Exception $e */
2455                 $e = null;
2456                 do {
2457                         try {
2458                                 $retVal = call_user_func_array( $function, $args );
2459                                 break;
2460                         } catch ( DBQueryError $e ) {
2461                                 if ( $this->wasDeadlock() ) {
2462                                         // Retry after a randomized delay
2463                                         usleep( mt_rand( self::DEADLOCK_DELAY_MIN, self::DEADLOCK_DELAY_MAX ) );
2464                                 } else {
2465                                         // Throw the error back up
2466                                         throw $e;
2467                                 }
2468                         }
2469                 } while ( --$tries > 0 );
2470
2471                 if ( $tries <= 0 ) {
2472                         // Too many deadlocks; give up
2473                         $this->rollback( __METHOD__ );
2474                         throw $e;
2475                 } else {
2476                         $this->commit( __METHOD__ );
2477
2478                         return $retVal;
2479                 }
2480         }
2481
2482         public function masterPosWait( DBMasterPos $pos, $timeout ) {
2483                 # Real waits are implemented in the subclass.
2484                 return 0;
2485         }
2486
2487         public function getReplicaPos() {
2488                 # Stub
2489                 return false;
2490         }
2491
2492         public function getMasterPos() {
2493                 # Stub
2494                 return false;
2495         }
2496
2497         public function serverIsReadOnly() {
2498                 return false;
2499         }
2500
2501         final public function onTransactionResolution( callable $callback, $fname = __METHOD__ ) {
2502                 if ( !$this->mTrxLevel ) {
2503                         throw new DBUnexpectedError( $this, "No transaction is active." );
2504                 }
2505                 $this->mTrxEndCallbacks[] = [ $callback, $fname ];
2506         }
2507
2508         final public function onTransactionIdle( callable $callback, $fname = __METHOD__ ) {
2509                 $this->mTrxIdleCallbacks[] = [ $callback, $fname ];
2510                 if ( !$this->mTrxLevel ) {
2511                         $this->runOnTransactionIdleCallbacks( self::TRIGGER_IDLE );
2512                 }
2513         }
2514
2515         final public function onTransactionPreCommitOrIdle( callable $callback, $fname = __METHOD__ ) {
2516                 if ( $this->mTrxLevel ) {
2517                         $this->mTrxPreCommitCallbacks[] = [ $callback, $fname ];
2518                 } else {
2519                         // If no transaction is active, then make one for this callback
2520                         $this->startAtomic( __METHOD__ );
2521                         try {
2522                                 call_user_func( $callback );
2523                                 $this->endAtomic( __METHOD__ );
2524                         } catch ( Exception $e ) {
2525                                 $this->rollback( __METHOD__, self::FLUSHING_INTERNAL );
2526                                 throw $e;
2527                         }
2528                 }
2529         }
2530
2531         final public function setTransactionListener( $name, callable $callback = null ) {
2532                 if ( $callback ) {
2533                         $this->mTrxRecurringCallbacks[$name] = $callback;
2534                 } else {
2535                         unset( $this->mTrxRecurringCallbacks[$name] );
2536                 }
2537         }
2538
2539         /**
2540          * Whether to disable running of post-COMMIT/ROLLBACK callbacks
2541          *
2542          * This method should not be used outside of Database/LoadBalancer
2543          *
2544          * @param bool $suppress
2545          * @since 1.28
2546          */
2547         final public function setTrxEndCallbackSuppression( $suppress ) {
2548                 $this->mTrxEndCallbacksSuppressed = $suppress;
2549         }
2550
2551         /**
2552          * Actually run and consume any "on transaction idle/resolution" callbacks.
2553          *
2554          * This method should not be used outside of Database/LoadBalancer
2555          *
2556          * @param integer $trigger IDatabase::TRIGGER_* constant
2557          * @since 1.20
2558          * @throws Exception
2559          */
2560         public function runOnTransactionIdleCallbacks( $trigger ) {
2561                 if ( $this->mTrxEndCallbacksSuppressed ) {
2562                         return;
2563                 }
2564
2565                 $autoTrx = $this->getFlag( self::DBO_TRX ); // automatic begin() enabled?
2566                 /** @var Exception $e */
2567                 $e = null; // first exception
2568                 do { // callbacks may add callbacks :)
2569                         $callbacks = array_merge(
2570                                 $this->mTrxIdleCallbacks,
2571                                 $this->mTrxEndCallbacks // include "transaction resolution" callbacks
2572                         );
2573                         $this->mTrxIdleCallbacks = []; // consumed (and recursion guard)
2574                         $this->mTrxEndCallbacks = []; // consumed (recursion guard)
2575                         foreach ( $callbacks as $callback ) {
2576                                 try {
2577                                         list( $phpCallback ) = $callback;
2578                                         $this->clearFlag( self::DBO_TRX ); // make each query its own transaction
2579                                         call_user_func_array( $phpCallback, [ $trigger ] );
2580                                         if ( $autoTrx ) {
2581                                                 $this->setFlag( self::DBO_TRX ); // restore automatic begin()
2582                                         } else {
2583                                                 $this->clearFlag( self::DBO_TRX ); // restore auto-commit
2584                                         }
2585                                 } catch ( Exception $ex ) {
2586                                         call_user_func( $this->errorLogger, $ex );
2587                                         $e = $e ?: $ex;
2588                                         // Some callbacks may use startAtomic/endAtomic, so make sure
2589                                         // their transactions are ended so other callbacks don't fail
2590                                         if ( $this->trxLevel() ) {
2591                                                 $this->rollback( __METHOD__, self::FLUSHING_INTERNAL );
2592                                         }
2593                                 }
2594                         }
2595                 } while ( count( $this->mTrxIdleCallbacks ) );
2596
2597                 if ( $e instanceof Exception ) {
2598                         throw $e; // re-throw any first exception
2599                 }
2600         }
2601
2602         /**
2603          * Actually run and consume any "on transaction pre-commit" callbacks.
2604          *
2605          * This method should not be used outside of Database/LoadBalancer
2606          *
2607          * @since 1.22
2608          * @throws Exception
2609          */
2610         public function runOnTransactionPreCommitCallbacks() {
2611                 $e = null; // first exception
2612                 do { // callbacks may add callbacks :)
2613                         $callbacks = $this->mTrxPreCommitCallbacks;
2614                         $this->mTrxPreCommitCallbacks = []; // consumed (and recursion guard)
2615                         foreach ( $callbacks as $callback ) {
2616                                 try {
2617                                         list( $phpCallback ) = $callback;
2618                                         call_user_func( $phpCallback );
2619                                 } catch ( Exception $ex ) {
2620                                         call_user_func( $this->errorLogger, $ex );
2621                                         $e = $e ?: $ex;
2622                                 }
2623                         }
2624                 } while ( count( $this->mTrxPreCommitCallbacks ) );
2625
2626                 if ( $e instanceof Exception ) {
2627                         throw $e; // re-throw any first exception
2628                 }
2629         }
2630
2631         /**
2632          * Actually run any "transaction listener" callbacks.
2633          *
2634          * This method should not be used outside of Database/LoadBalancer
2635          *
2636          * @param integer $trigger IDatabase::TRIGGER_* constant
2637          * @throws Exception
2638          * @since 1.20
2639          */
2640         public function runTransactionListenerCallbacks( $trigger ) {
2641                 if ( $this->mTrxEndCallbacksSuppressed ) {
2642                         return;
2643                 }
2644
2645                 /** @var Exception $e */
2646                 $e = null; // first exception
2647
2648                 foreach ( $this->mTrxRecurringCallbacks as $phpCallback ) {
2649                         try {
2650                                 $phpCallback( $trigger, $this );
2651                         } catch ( Exception $ex ) {
2652                                 call_user_func( $this->errorLogger, $ex );
2653                                 $e = $e ?: $ex;
2654                         }
2655                 }
2656
2657                 if ( $e instanceof Exception ) {
2658                         throw $e; // re-throw any first exception
2659                 }
2660         }
2661
2662         final public function startAtomic( $fname = __METHOD__ ) {
2663                 if ( !$this->mTrxLevel ) {
2664                         $this->begin( $fname, self::TRANSACTION_INTERNAL );
2665                         // If DBO_TRX is set, a series of startAtomic/endAtomic pairs will result
2666                         // in all changes being in one transaction to keep requests transactional.
2667                         if ( !$this->getFlag( self::DBO_TRX ) ) {
2668                                 $this->mTrxAutomaticAtomic = true;
2669                         }
2670                 }
2671
2672                 $this->mTrxAtomicLevels[] = $fname;
2673         }
2674
2675         final public function endAtomic( $fname = __METHOD__ ) {
2676                 if ( !$this->mTrxLevel ) {
2677                         throw new DBUnexpectedError( $this, "No atomic transaction is open (got $fname)." );
2678                 }
2679                 if ( !$this->mTrxAtomicLevels ||
2680                         array_pop( $this->mTrxAtomicLevels ) !== $fname
2681                 ) {
2682                         throw new DBUnexpectedError( $this, "Invalid atomic section ended (got $fname)." );
2683                 }
2684
2685                 if ( !$this->mTrxAtomicLevels && $this->mTrxAutomaticAtomic ) {
2686                         $this->commit( $fname, self::FLUSHING_INTERNAL );
2687                 }
2688         }
2689
2690         final public function doAtomicSection( $fname, callable $callback ) {
2691                 $this->startAtomic( $fname );
2692                 try {
2693                         $res = call_user_func_array( $callback, [ $this, $fname ] );
2694                 } catch ( Exception $e ) {
2695                         $this->rollback( $fname, self::FLUSHING_INTERNAL );
2696                         throw $e;
2697                 }
2698                 $this->endAtomic( $fname );
2699
2700                 return $res;
2701         }
2702
2703         final public function begin( $fname = __METHOD__, $mode = self::TRANSACTION_EXPLICIT ) {
2704                 // Protect against mismatched atomic section, transaction nesting, and snapshot loss
2705                 if ( $this->mTrxLevel ) {
2706                         if ( $this->mTrxAtomicLevels ) {
2707                                 $levels = implode( ', ', $this->mTrxAtomicLevels );
2708                                 $msg = "$fname: Got explicit BEGIN while atomic section(s) $levels are open.";
2709                                 throw new DBUnexpectedError( $this, $msg );
2710                         } elseif ( !$this->mTrxAutomatic ) {
2711                                 $msg = "$fname: Explicit transaction already active (from {$this->mTrxFname}).";
2712                                 throw new DBUnexpectedError( $this, $msg );
2713                         } else {
2714                                 // @TODO: make this an exception at some point
2715                                 $msg = "$fname: Implicit transaction already active (from {$this->mTrxFname}).";
2716                                 $this->queryLogger->error( $msg );
2717                                 return; // join the main transaction set
2718                         }
2719                 } elseif ( $this->getFlag( self::DBO_TRX ) && $mode !== self::TRANSACTION_INTERNAL ) {
2720                         // @TODO: make this an exception at some point
2721                         $msg = "$fname: Implicit transaction expected (DBO_TRX set).";
2722                         $this->queryLogger->error( $msg );
2723                         return; // let any writes be in the main transaction
2724                 }
2725
2726                 // Avoid fatals if close() was called
2727                 $this->assertOpen();
2728
2729                 $this->doBegin( $fname );
2730                 $this->mTrxTimestamp = microtime( true );
2731                 $this->mTrxFname = $fname;
2732                 $this->mTrxDoneWrites = false;
2733                 $this->mTrxAutomaticAtomic = false;
2734                 $this->mTrxAtomicLevels = [];
2735                 $this->mTrxShortId = sprintf( '%06x', mt_rand( 0, 0xffffff ) );
2736                 $this->mTrxWriteDuration = 0.0;
2737                 $this->mTrxWriteQueryCount = 0;
2738                 $this->mTrxWriteAdjDuration = 0.0;
2739                 $this->mTrxWriteAdjQueryCount = 0;
2740                 $this->mTrxWriteCallers = [];
2741                 // First SELECT after BEGIN will establish the snapshot in REPEATABLE-READ.
2742                 // Get an estimate of the replica DB lag before then, treating estimate staleness
2743                 // as lag itself just to be safe
2744                 $status = $this->getApproximateLagStatus();
2745                 $this->mTrxReplicaLag = $status['lag'] + ( microtime( true ) - $status['since'] );
2746                 // T147697: make explicitTrxActive() return true until begin() finishes. This way, no
2747                 // caller will think its OK to muck around with the transaction just because startAtomic()
2748                 // has not yet completed (e.g. setting mTrxAtomicLevels).
2749                 $this->mTrxAutomatic = ( $mode === self::TRANSACTION_INTERNAL );
2750         }
2751
2752         /**
2753          * Issues the BEGIN command to the database server.
2754          *
2755          * @see Database::begin()
2756          * @param string $fname
2757          */
2758         protected function doBegin( $fname ) {
2759                 $this->query( 'BEGIN', $fname );
2760                 $this->mTrxLevel = 1;
2761         }
2762
2763         final public function commit( $fname = __METHOD__, $flush = '' ) {
2764                 if ( $this->mTrxLevel && $this->mTrxAtomicLevels ) {
2765                         // There are still atomic sections open. This cannot be ignored
2766                         $levels = implode( ', ', $this->mTrxAtomicLevels );
2767                         throw new DBUnexpectedError(
2768                                 $this,
2769                                 "$fname: Got COMMIT while atomic sections $levels are still open."
2770                         );
2771                 }
2772
2773                 if ( $flush === self::FLUSHING_INTERNAL || $flush === self::FLUSHING_ALL_PEERS ) {
2774                         if ( !$this->mTrxLevel ) {
2775                                 return; // nothing to do
2776                         } elseif ( !$this->mTrxAutomatic ) {
2777                                 throw new DBUnexpectedError(
2778                                         $this,
2779                                         "$fname: Flushing an explicit transaction, getting out of sync."
2780                                 );
2781                         }
2782                 } else {
2783                         if ( !$this->mTrxLevel ) {
2784                                 $this->queryLogger->error(
2785                                         "$fname: No transaction to commit, something got out of sync." );
2786                                 return; // nothing to do
2787                         } elseif ( $this->mTrxAutomatic ) {
2788                                 // @TODO: make this an exception at some point
2789                                 $msg = "$fname: Explicit commit of implicit transaction.";
2790                                 $this->queryLogger->error( $msg );
2791                                 return; // wait for the main transaction set commit round
2792                         }
2793                 }
2794
2795                 // Avoid fatals if close() was called
2796                 $this->assertOpen();
2797
2798                 $this->runOnTransactionPreCommitCallbacks();
2799                 $writeTime = $this->pendingWriteQueryDuration( self::ESTIMATE_DB_APPLY );
2800                 $this->doCommit( $fname );
2801                 if ( $this->mTrxDoneWrites ) {
2802                         $this->mLastWriteTime = microtime( true );
2803                         $this->trxProfiler->transactionWritingOut(
2804                                 $this->mServer, $this->mDBname, $this->mTrxShortId, $writeTime );
2805                 }
2806
2807                 $this->runOnTransactionIdleCallbacks( self::TRIGGER_COMMIT );
2808                 $this->runTransactionListenerCallbacks( self::TRIGGER_COMMIT );
2809         }
2810
2811         /**
2812          * Issues the COMMIT command to the database server.
2813          *
2814          * @see Database::commit()
2815          * @param string $fname
2816          */
2817         protected function doCommit( $fname ) {
2818                 if ( $this->mTrxLevel ) {
2819                         $this->query( 'COMMIT', $fname );
2820                         $this->mTrxLevel = 0;
2821                 }
2822         }
2823
2824         final public function rollback( $fname = __METHOD__, $flush = '' ) {
2825                 if ( $flush === self::FLUSHING_INTERNAL || $flush === self::FLUSHING_ALL_PEERS ) {
2826                         if ( !$this->mTrxLevel ) {
2827                                 return; // nothing to do
2828                         }
2829                 } else {
2830                         if ( !$this->mTrxLevel ) {
2831                                 $this->queryLogger->error(
2832                                         "$fname: No transaction to rollback, something got out of sync." );
2833                                 return; // nothing to do
2834                         } elseif ( $this->getFlag( self::DBO_TRX ) ) {
2835                                 throw new DBUnexpectedError(
2836                                         $this,
2837                                         "$fname: Expected mass rollback of all peer databases (DBO_TRX set)."
2838                                 );
2839                         }
2840                 }
2841
2842                 // Avoid fatals if close() was called
2843                 $this->assertOpen();
2844
2845                 $this->doRollback( $fname );
2846                 $this->mTrxAtomicLevels = [];
2847                 if ( $this->mTrxDoneWrites ) {
2848                         $this->trxProfiler->transactionWritingOut(
2849                                 $this->mServer, $this->mDBname, $this->mTrxShortId );
2850                 }
2851
2852                 $this->mTrxIdleCallbacks = []; // clear
2853                 $this->mTrxPreCommitCallbacks = []; // clear
2854                 $this->runOnTransactionIdleCallbacks( self::TRIGGER_ROLLBACK );
2855                 $this->runTransactionListenerCallbacks( self::TRIGGER_ROLLBACK );
2856         }
2857
2858         /**
2859          * Issues the ROLLBACK command to the database server.
2860          *
2861          * @see Database::rollback()
2862          * @param string $fname
2863          */
2864         protected function doRollback( $fname ) {
2865                 if ( $this->mTrxLevel ) {
2866                         # Disconnects cause rollback anyway, so ignore those errors
2867                         $ignoreErrors = true;
2868                         $this->query( 'ROLLBACK', $fname, $ignoreErrors );
2869                         $this->mTrxLevel = 0;
2870                 }
2871         }
2872
2873         public function flushSnapshot( $fname = __METHOD__ ) {
2874                 if ( $this->writesOrCallbacksPending() || $this->explicitTrxActive() ) {
2875                         // This only flushes transactions to clear snapshots, not to write data
2876                         $fnames = implode( ', ', $this->pendingWriteAndCallbackCallers() );
2877                         throw new DBUnexpectedError(
2878                                 $this,
2879                                 "$fname: Cannot flush snapshot because writes are pending ($fnames)."
2880                         );
2881                 }
2882
2883                 $this->commit( $fname, self::FLUSHING_INTERNAL );
2884         }
2885
2886         public function explicitTrxActive() {
2887                 return $this->mTrxLevel && ( $this->mTrxAtomicLevels || !$this->mTrxAutomatic );
2888         }
2889
2890         public function duplicateTableStructure(
2891                 $oldName, $newName, $temporary = false, $fname = __METHOD__
2892         ) {
2893                 throw new RuntimeException( __METHOD__ . ' is not implemented in descendant class' );
2894         }
2895
2896         public function listTables( $prefix = null, $fname = __METHOD__ ) {
2897                 throw new RuntimeException( __METHOD__ . ' is not implemented in descendant class' );
2898         }
2899
2900         public function listViews( $prefix = null, $fname = __METHOD__ ) {
2901                 throw new RuntimeException( __METHOD__ . ' is not implemented in descendant class' );
2902         }
2903
2904         public function timestamp( $ts = 0 ) {
2905                 $t = new ConvertibleTimestamp( $ts );
2906                 // Let errors bubble up to avoid putting garbage in the DB
2907                 return $t->getTimestamp( TS_MW );
2908         }
2909
2910         public function timestampOrNull( $ts = null ) {
2911                 if ( is_null( $ts ) ) {
2912                         return null;
2913                 } else {
2914                         return $this->timestamp( $ts );
2915                 }
2916         }
2917
2918         /**
2919          * Take the result from a query, and wrap it in a ResultWrapper if
2920          * necessary. Boolean values are passed through as is, to indicate success
2921          * of write queries or failure.
2922          *
2923          * Once upon a time, Database::query() returned a bare MySQL result
2924          * resource, and it was necessary to call this function to convert it to
2925          * a wrapper. Nowadays, raw database objects are never exposed to external
2926          * callers, so this is unnecessary in external code.
2927          *
2928          * @param bool|ResultWrapper|resource|object $result
2929          * @return bool|ResultWrapper
2930          */
2931         protected function resultObject( $result ) {
2932                 if ( !$result ) {
2933                         return false;
2934                 } elseif ( $result instanceof ResultWrapper ) {
2935                         return $result;
2936                 } elseif ( $result === true ) {
2937                         // Successful write query
2938                         return $result;
2939                 } else {
2940                         return new ResultWrapper( $this, $result );
2941                 }
2942         }
2943
2944         public function ping( &$rtt = null ) {
2945                 // Avoid hitting the server if it was hit recently
2946                 if ( $this->isOpen() && ( microtime( true ) - $this->lastPing ) < self::PING_TTL ) {
2947                         if ( !func_num_args() || $this->mRTTEstimate > 0 ) {
2948                                 $rtt = $this->mRTTEstimate;
2949                                 return true; // don't care about $rtt
2950                         }
2951                 }
2952
2953                 // This will reconnect if possible or return false if not
2954                 $this->clearFlag( self::DBO_TRX, self::REMEMBER_PRIOR );
2955                 $ok = ( $this->query( self::PING_QUERY, __METHOD__, true ) !== false );
2956                 $this->restoreFlags( self::RESTORE_PRIOR );
2957
2958                 if ( $ok ) {
2959                         $rtt = $this->mRTTEstimate;
2960                 }
2961
2962                 return $ok;
2963         }
2964
2965         /**
2966          * @return bool
2967          */
2968         protected function reconnect() {
2969                 $this->closeConnection();
2970                 $this->mOpened = false;
2971                 $this->mConn = false;
2972                 try {
2973                         $this->open( $this->mServer, $this->mUser, $this->mPassword, $this->mDBname );
2974                         $this->lastPing = microtime( true );
2975                         $ok = true;
2976                 } catch ( DBConnectionError $e ) {
2977                         $ok = false;
2978                 }
2979
2980                 return $ok;
2981         }
2982
2983         public function getSessionLagStatus() {
2984                 return $this->getTransactionLagStatus() ?: $this->getApproximateLagStatus();
2985         }
2986
2987         /**
2988          * Get the replica DB lag when the current transaction started
2989          *
2990          * This is useful when transactions might use snapshot isolation
2991          * (e.g. REPEATABLE-READ in innodb), so the "real" lag of that data
2992          * is this lag plus transaction duration. If they don't, it is still
2993          * safe to be pessimistic. This returns null if there is no transaction.
2994          *
2995          * @return array|null ('lag': seconds or false on error, 'since': UNIX timestamp of BEGIN)
2996          * @since 1.27
2997          */
2998         protected function getTransactionLagStatus() {
2999                 return $this->mTrxLevel
3000                         ? [ 'lag' => $this->mTrxReplicaLag, 'since' => $this->trxTimestamp() ]
3001                         : null;
3002         }
3003
3004         /**
3005          * Get a replica DB lag estimate for this server
3006          *
3007          * @return array ('lag': seconds or false on error, 'since': UNIX timestamp of estimate)
3008          * @since 1.27
3009          */
3010         protected function getApproximateLagStatus() {
3011                 return [
3012                         'lag'   => $this->getLBInfo( 'replica' ) ? $this->getLag() : 0,
3013                         'since' => microtime( true )
3014                 ];
3015         }
3016
3017         /**
3018          * Merge the result of getSessionLagStatus() for several DBs
3019          * using the most pessimistic values to estimate the lag of
3020          * any data derived from them in combination
3021          *
3022          * This is information is useful for caching modules
3023          *
3024          * @see WANObjectCache::set()
3025          * @see WANObjectCache::getWithSetCallback()
3026          *
3027          * @param IDatabase $db1
3028          * @param IDatabase ...
3029          * @return array Map of values:
3030          *   - lag: highest lag of any of the DBs or false on error (e.g. replication stopped)
3031          *   - since: oldest UNIX timestamp of any of the DB lag estimates
3032          *   - pending: whether any of the DBs have uncommitted changes
3033          * @since 1.27
3034          */
3035         public static function getCacheSetOptions( IDatabase $db1 ) {
3036                 $res = [ 'lag' => 0, 'since' => INF, 'pending' => false ];
3037                 foreach ( func_get_args() as $db ) {
3038                         /** @var IDatabase $db */
3039                         $status = $db->getSessionLagStatus();
3040                         if ( $status['lag'] === false ) {
3041                                 $res['lag'] = false;
3042                         } elseif ( $res['lag'] !== false ) {
3043                                 $res['lag'] = max( $res['lag'], $status['lag'] );
3044                         }
3045                         $res['since'] = min( $res['since'], $status['since'] );
3046                         $res['pending'] = $res['pending'] ?: $db->writesPending();
3047                 }
3048
3049                 return $res;
3050         }
3051
3052         public function getLag() {
3053                 return 0;
3054         }
3055
3056         public function maxListLen() {
3057                 return 0;
3058         }
3059
3060         public function encodeBlob( $b ) {
3061                 return $b;
3062         }
3063
3064         public function decodeBlob( $b ) {
3065                 if ( $b instanceof Blob ) {
3066                         $b = $b->fetch();
3067                 }
3068                 return $b;
3069         }
3070
3071         public function setSessionOptions( array $options ) {
3072         }
3073
3074         public function sourceFile(
3075                 $filename,
3076                 callable $lineCallback = null,
3077                 callable $resultCallback = null,
3078                 $fname = false,
3079                 callable $inputCallback = null
3080         ) {
3081                 MediaWiki\suppressWarnings();
3082                 $fp = fopen( $filename, 'r' );
3083                 MediaWiki\restoreWarnings();
3084
3085                 if ( false === $fp ) {
3086                         throw new RuntimeException( "Could not open \"{$filename}\".\n" );
3087                 }
3088
3089                 if ( !$fname ) {
3090                         $fname = __METHOD__ . "( $filename )";
3091                 }
3092
3093                 try {
3094                         $error = $this->sourceStream(
3095                                 $fp, $lineCallback, $resultCallback, $fname, $inputCallback );
3096                 } catch ( Exception $e ) {
3097                         fclose( $fp );
3098                         throw $e;
3099                 }
3100
3101                 fclose( $fp );
3102
3103                 return $error;
3104         }
3105
3106         public function setSchemaVars( $vars ) {
3107                 $this->mSchemaVars = $vars;
3108         }
3109
3110         public function sourceStream(
3111                 $fp,
3112                 callable $lineCallback = null,
3113                 callable $resultCallback = null,
3114                 $fname = __METHOD__,
3115                 callable $inputCallback = null
3116         ) {
3117                 $cmd = '';
3118
3119                 while ( !feof( $fp ) ) {
3120                         if ( $lineCallback ) {
3121                                 call_user_func( $lineCallback );
3122                         }
3123
3124                         $line = trim( fgets( $fp ) );
3125
3126                         if ( $line == '' ) {
3127                                 continue;
3128                         }
3129
3130                         if ( '-' == $line[0] && '-' == $line[1] ) {
3131                                 continue;
3132                         }
3133
3134                         if ( $cmd != '' ) {
3135                                 $cmd .= ' ';
3136                         }
3137
3138                         $done = $this->streamStatementEnd( $cmd, $line );
3139
3140                         $cmd .= "$line\n";
3141
3142                         if ( $done || feof( $fp ) ) {
3143                                 $cmd = $this->replaceVars( $cmd );
3144
3145                                 if ( !$inputCallback || call_user_func( $inputCallback, $cmd ) ) {
3146                                         $res = $this->query( $cmd, $fname );
3147
3148                                         if ( $resultCallback ) {
3149                                                 call_user_func( $resultCallback, $res, $this );
3150                                         }
3151
3152                                         if ( false === $res ) {
3153                                                 $err = $this->lastError();
3154
3155                                                 return "Query \"{$cmd}\" failed with error code \"$err\".\n";
3156                                         }
3157                                 }
3158                                 $cmd = '';
3159                         }
3160                 }
3161
3162                 return true;
3163         }
3164
3165         /**
3166          * Called by sourceStream() to check if we've reached a statement end
3167          *
3168          * @param string &$sql SQL assembled so far
3169          * @param string &$newLine New line about to be added to $sql
3170          * @return bool Whether $newLine contains end of the statement
3171          */
3172         public function streamStatementEnd( &$sql, &$newLine ) {
3173                 if ( $this->delimiter ) {
3174                         $prev = $newLine;
3175                         $newLine = preg_replace(
3176                                 '/' . preg_quote( $this->delimiter, '/' ) . '$/', '', $newLine );
3177                         if ( $newLine != $prev ) {
3178                                 return true;
3179                         }
3180                 }
3181
3182                 return false;
3183         }
3184
3185         /**
3186          * Database independent variable replacement. Replaces a set of variables
3187          * in an SQL statement with their contents as given by $this->getSchemaVars().
3188          *
3189          * Supports '{$var}' `{$var}` and / *$var* / (without the spaces) style variables.
3190          *
3191          * - '{$var}' should be used for text and is passed through the database's
3192          *   addQuotes method.
3193          * - `{$var}` should be used for identifiers (e.g. table and database names).
3194          *   It is passed through the database's addIdentifierQuotes method which
3195          *   can be overridden if the database uses something other than backticks.
3196          * - / *_* / or / *$wgDBprefix* / passes the name that follows through the
3197          *   database's tableName method.
3198          * - / *i* / passes the name that follows through the database's indexName method.
3199          * - In all other cases, / *$var* / is left unencoded. Except for table options,
3200          *   its use should be avoided. In 1.24 and older, string encoding was applied.
3201          *
3202          * @param string $ins SQL statement to replace variables in
3203          * @return string The new SQL statement with variables replaced
3204          */
3205         protected function replaceVars( $ins ) {
3206                 $vars = $this->getSchemaVars();
3207                 return preg_replace_callback(
3208                         '!
3209                                 /\* (\$wgDBprefix|[_i]) \*/ (\w*) | # 1-2. tableName, indexName
3210                                 \'\{\$ (\w+) }\'                  | # 3. addQuotes
3211                                 `\{\$ (\w+) }`                    | # 4. addIdentifierQuotes
3212                                 /\*\$ (\w+) \*/                     # 5. leave unencoded
3213                         !x',
3214                         function ( $m ) use ( $vars ) {
3215                                 // Note: Because of <https://bugs.php.net/bug.php?id=51881>,
3216                                 // check for both nonexistent keys *and* the empty string.
3217                                 if ( isset( $m[1] ) && $m[1] !== '' ) {
3218                                         if ( $m[1] === 'i' ) {
3219                                                 return $this->indexName( $m[2] );
3220                                         } else {
3221                                                 return $this->tableName( $m[2] );
3222                                         }
3223                                 } elseif ( isset( $m[3] ) && $m[3] !== '' && array_key_exists( $m[3], $vars ) ) {
3224                                         return $this->addQuotes( $vars[$m[3]] );
3225                                 } elseif ( isset( $m[4] ) && $m[4] !== '' && array_key_exists( $m[4], $vars ) ) {
3226                                         return $this->addIdentifierQuotes( $vars[$m[4]] );
3227                                 } elseif ( isset( $m[5] ) && $m[5] !== '' && array_key_exists( $m[5], $vars ) ) {
3228                                         return $vars[$m[5]];
3229                                 } else {
3230                                         return $m[0];
3231                                 }
3232                         },
3233                         $ins
3234                 );
3235         }
3236
3237         /**
3238          * Get schema variables. If none have been set via setSchemaVars(), then
3239          * use some defaults from the current object.
3240          *
3241          * @return array
3242          */
3243         protected function getSchemaVars() {
3244                 if ( $this->mSchemaVars ) {
3245                         return $this->mSchemaVars;
3246                 } else {
3247                         return $this->getDefaultSchemaVars();
3248                 }
3249         }
3250
3251         /**
3252          * Get schema variables to use if none have been set via setSchemaVars().
3253          *
3254          * Override this in derived classes to provide variables for tables.sql
3255          * and SQL patch files.
3256          *
3257          * @return array
3258          */
3259         protected function getDefaultSchemaVars() {
3260                 return [];
3261         }
3262
3263         public function lockIsFree( $lockName, $method ) {
3264                 return true;
3265         }
3266
3267         public function lock( $lockName, $method, $timeout = 5 ) {
3268                 $this->mNamedLocksHeld[$lockName] = 1;
3269
3270                 return true;
3271         }
3272
3273         public function unlock( $lockName, $method ) {
3274                 unset( $this->mNamedLocksHeld[$lockName] );
3275
3276                 return true;
3277         }
3278
3279         public function getScopedLockAndFlush( $lockKey, $fname, $timeout ) {
3280                 if ( $this->writesOrCallbacksPending() ) {
3281                         // This only flushes transactions to clear snapshots, not to write data
3282                         $fnames = implode( ', ', $this->pendingWriteAndCallbackCallers() );
3283                         throw new DBUnexpectedError(
3284                                 $this,
3285                                 "$fname: Cannot flush pre-lock snapshot because writes are pending ($fnames)."
3286                         );
3287                 }
3288
3289                 if ( !$this->lock( $lockKey, $fname, $timeout ) ) {
3290                         return null;
3291                 }
3292
3293                 $unlocker = new ScopedCallback( function () use ( $lockKey, $fname ) {
3294                         if ( $this->trxLevel() ) {
3295                                 // There is a good chance an exception was thrown, causing any early return
3296                                 // from the caller. Let any error handler get a chance to issue rollback().
3297                                 // If there isn't one, let the error bubble up and trigger server-side rollback.
3298                                 $this->onTransactionResolution(
3299                                         function () use ( $lockKey, $fname ) {
3300                                                 $this->unlock( $lockKey, $fname );
3301                                         },
3302                                         $fname
3303                                 );
3304                         } else {
3305                                 $this->unlock( $lockKey, $fname );
3306                         }
3307                 } );
3308
3309                 $this->commit( $fname, self::FLUSHING_INTERNAL );
3310
3311                 return $unlocker;
3312         }
3313
3314         public function namedLocksEnqueue() {
3315                 return false;
3316         }
3317
3318         public function tableLocksHaveTransactionScope() {
3319                 return true;
3320         }
3321
3322         final public function lockTables( array $read, array $write, $method ) {
3323                 if ( $this->writesOrCallbacksPending() ) {
3324                         throw new DBUnexpectedError( $this, "Transaction writes or callbacks still pending." );
3325                 }
3326
3327                 if ( $this->tableLocksHaveTransactionScope() ) {
3328                         $this->startAtomic( $method );
3329                 }
3330
3331                 return $this->doLockTables( $read, $write, $method );
3332         }
3333
3334         protected function doLockTables( array $read, array $write, $method ) {
3335                 return true;
3336         }
3337
3338         final public function unlockTables( $method ) {
3339                 if ( $this->tableLocksHaveTransactionScope() ) {
3340                         $this->endAtomic( $method );
3341
3342                         return true; // locks released on COMMIT/ROLLBACK
3343                 }
3344
3345                 return $this->doUnlockTables( $method );
3346         }
3347
3348         protected function doUnlockTables( $method ) {
3349                 return true;
3350         }
3351
3352         /**
3353          * Delete a table
3354          * @param string $tableName
3355          * @param string $fName
3356          * @return bool|ResultWrapper
3357          * @since 1.18
3358          */
3359         public function dropTable( $tableName, $fName = __METHOD__ ) {
3360                 if ( !$this->tableExists( $tableName, $fName ) ) {
3361                         return false;
3362                 }
3363                 $sql = "DROP TABLE " . $this->tableName( $tableName ) . " CASCADE";
3364
3365                 return $this->query( $sql, $fName );
3366         }
3367
3368         public function getInfinity() {
3369                 return 'infinity';
3370         }
3371
3372         public function encodeExpiry( $expiry ) {
3373                 return ( $expiry == '' || $expiry == 'infinity' || $expiry == $this->getInfinity() )
3374                         ? $this->getInfinity()
3375                         : $this->timestamp( $expiry );
3376         }
3377
3378         public function decodeExpiry( $expiry, $format = TS_MW ) {
3379                 if ( $expiry == '' || $expiry == 'infinity' || $expiry == $this->getInfinity() ) {
3380                         return 'infinity';
3381                 }
3382
3383                 return ConvertibleTimestamp::convert( $format, $expiry );
3384         }
3385
3386         public function setBigSelects( $value = true ) {
3387                 // no-op
3388         }
3389
3390         public function isReadOnly() {
3391                 return ( $this->getReadOnlyReason() !== false );
3392         }
3393
3394         /**
3395          * @return string|bool Reason this DB is read-only or false if it is not
3396          */
3397         protected function getReadOnlyReason() {
3398                 $reason = $this->getLBInfo( 'readOnlyReason' );
3399
3400                 return is_string( $reason ) ? $reason : false;
3401         }
3402
3403         public function setTableAliases( array $aliases ) {
3404                 $this->tableAliases = $aliases;
3405         }
3406
3407         /**
3408          * @return bool Whether a DB user is required to access the DB
3409          * @since 1.28
3410          */
3411         protected function requiresDatabaseUser() {
3412                 return true;
3413         }
3414
3415         /**
3416          * Get the underlying binding handle, mConn
3417          *
3418          * Makes sure that mConn is set (disconnects and ping() failure can unset it).
3419          * This catches broken callers than catch and ignore disconnection exceptions.
3420          * Unlike checking isOpen(), this is safe to call inside of open().
3421          *
3422          * @return resource|object
3423          * @throws DBUnexpectedError
3424          * @since 1.26
3425          */
3426         protected function getBindingHandle() {
3427                 if ( !$this->mConn ) {
3428                         throw new DBUnexpectedError(
3429                                 $this,
3430                                 'DB connection was already closed or the connection dropped.'
3431                         );
3432                 }
3433
3434                 return $this->mConn;
3435         }
3436
3437         /**
3438          * @since 1.19
3439          * @return string
3440          */
3441         public function __toString() {
3442                 return (string)$this->mConn;
3443         }
3444
3445         /**
3446          * Make sure that copies do not share the same client binding handle
3447          * @throws DBConnectionError
3448          */
3449         public function __clone() {
3450                 $this->connLogger->warning(
3451                         "Cloning " . static::class . " is not recomended; forking connection:\n" .
3452                         ( new RuntimeException() )->getTraceAsString()
3453                 );
3454
3455                 if ( $this->isOpen() ) {
3456                         // Open a new connection resource without messing with the old one
3457                         $this->mOpened = false;
3458                         $this->mConn = false;
3459                         $this->mTrxEndCallbacks = []; // don't copy
3460                         $this->handleSessionLoss(); // no trx or locks anymore
3461                         $this->open( $this->mServer, $this->mUser, $this->mPassword, $this->mDBname );
3462                         $this->lastPing = microtime( true );
3463                 }
3464         }
3465
3466         /**
3467          * Called by serialize. Throw an exception when DB connection is serialized.
3468          * This causes problems on some database engines because the connection is
3469          * not restored on unserialize.
3470          */
3471         public function __sleep() {
3472                 throw new RuntimeException( 'Database serialization may cause problems, since ' .
3473                         'the connection is not restored on wakeup.' );
3474         }
3475
3476         /**
3477          * Run a few simple sanity checks and close dangling connections
3478          */
3479         public function __destruct() {
3480                 if ( $this->mTrxLevel && $this->mTrxDoneWrites ) {
3481                         trigger_error( "Uncommitted DB writes (transaction from {$this->mTrxFname})." );
3482                 }
3483
3484                 $danglingWriters = $this->pendingWriteAndCallbackCallers();
3485                 if ( $danglingWriters ) {
3486                         $fnames = implode( ', ', $danglingWriters );
3487                         trigger_error( "DB transaction writes or callbacks still pending ($fnames)." );
3488                 }
3489
3490                 if ( $this->mConn ) {
3491                         // Avoid connection leaks for sanity. Normally, resources close at script completion.
3492                         // The connection might already be closed in zend/hhvm by now, so suppress warnings.
3493                         \MediaWiki\suppressWarnings();
3494                         $this->closeConnection();
3495                         \MediaWiki\restoreWarnings();
3496                         $this->mConn = false;
3497                         $this->mOpened = false;
3498                 }
3499         }
3500 }
3501
3502 class_alias( Database::class, 'DatabaseBase' ); // b/c for old name
3503 class_alias( Database::class, 'Database' ); // b/c global alias