includes/libs/rdbms/database/Database.php

   1 <?php
   2 /**
   3  * @defgroup Database Database
   4  *
   5  * This file deals with database interface functions
   6  * and query specifics/optimisations.
   7  *
   8  * This program is free software; you can redistribute it and/or modify
   9  * it under the terms of the GNU General Public License as published by
  10  * the Free Software Foundation; either version 2 of the License, or
  11  * (at your option) any later version.
  12  *
  13  * This program is distributed in the hope that it will be useful,
  14  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  15  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
  16  * GNU General Public License for more details.
  17  *
  18  * You should have received a copy of the GNU General Public License along
  19  * with this program; if not, write to the Free Software Foundation, Inc.,
  20  * 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
  21  * http://www.gnu.org/copyleft/gpl.html
  22  *
  23  * @file
  24  * @ingroup Database
  25  */
  26 use Psr\Log\LoggerAwareInterface;
  27 use Psr\Log\LoggerInterface;
  28 use Wikimedia\ScopedCallback;
  29 use Wikimedia\Rdbms\TransactionProfiler;
  30 use Wikimedia\Rdbms\LikeMatch;
  31 use Wikimedia\Rdbms\DatabaseDomain;
  32
  33 /**
  34  * Relational database abstraction object
  35  *
  36  * @ingroup Database
  37  * @since 1.28
  38  */
  39 abstract class Database implements IDatabase, IMaintainableDatabase, LoggerAwareInterface {
  40         /** Number of times to re-try an operation in case of deadlock */
  41         const DEADLOCK_TRIES = 4;
  42         /** Minimum time to wait before retry, in microseconds */
  43         const DEADLOCK_DELAY_MIN = 500000;
  44         /** Maximum time to wait before retry */
  45         const DEADLOCK_DELAY_MAX = 1500000;
  46
  47         /** How long before it is worth doing a dummy query to test the connection */
  48         const PING_TTL = 1.0;
  49         const PING_QUERY = 'SELECT 1 AS ping';
  50
  51         const TINY_WRITE_SEC = .010;
  52         const SLOW_WRITE_SEC = .500;
  53         const SMALL_WRITE_ROWS = 100;
  54
  55         /** @var string SQL query */
  56         protected $mLastQuery = '';
  57         /** @var float|bool UNIX timestamp of last write query */
  58         protected $mLastWriteTime = false;
  59         /** @var string|bool */
  60         protected $mPHPError = false;
  61         /** @var string */
  62         protected $mServer;
  63         /** @var string */
  64         protected $mUser;
  65         /** @var string */
  66         protected $mPassword;
  67         /** @var string */
  68         protected $mDBname;
  69         /** @var array[] $aliases Map of (table => (dbname, schema, prefix) map) */
  70         protected $tableAliases = [];
  71         /** @var bool Whether this PHP instance is for a CLI script */
  72         protected $cliMode;
  73         /** @var string Agent name for query profiling */
  74         protected $agent;
  75
  76         /** @var BagOStuff APC cache */
  77         protected $srvCache;
  78         /** @var LoggerInterface */
  79         protected $connLogger;
  80         /** @var LoggerInterface */
  81         protected $queryLogger;
  82         /** @var callback Error logging callback */
  83         protected $errorLogger;
  84
  85         /** @var resource|null Database connection */
  86         protected $mConn = null;
  87         /** @var bool */
  88         protected $mOpened = false;
  89
  90         /** @var array[] List of (callable, method name) */
  91         protected $mTrxIdleCallbacks = [];
  92         /** @var array[] List of (callable, method name) */
  93         protected $mTrxPreCommitCallbacks = [];
  94         /** @var array[] List of (callable, method name) */
  95         protected $mTrxEndCallbacks = [];
  96         /** @var callable[] Map of (name => callable) */
  97         protected $mTrxRecurringCallbacks = [];
  98         /** @var bool Whether to suppress triggering of transaction end callbacks */
  99         protected $mTrxEndCallbacksSuppressed = false;
 100
 101         /** @var string */
 102         protected $mTablePrefix = '';
 103         /** @var string */
 104         protected $mSchema = '';
 105         /** @var integer */
 106         protected $mFlags;
 107         /** @var array */
 108         protected $mLBInfo = [];
 109         /** @var bool|null */
 110         protected $mDefaultBigSelects = null;
 111         /** @var array|bool */
 112         protected $mSchemaVars = false;
 113         /** @var array */
 114         protected $mSessionVars = [];
 115         /** @var array|null */
 116         protected $preparedArgs;
 117         /** @var string|bool|null Stashed value of html_errors INI setting */
 118         protected $htmlErrors;
 119         /** @var string */
 120         protected $delimiter = ';';
 121         /** @var DatabaseDomain */
 122         protected $currentDomain;
 123
 124         /**
 125          * Either 1 if a transaction is active or 0 otherwise.
 126          * The other Trx fields may not be meaningfull if this is 0.
 127          *
 128          * @var int
 129          */
 130         protected $mTrxLevel = 0;
 131         /**
 132          * Either a short hexidecimal string if a transaction is active or ""
 133          *
 134          * @var string
 135          * @see Database::mTrxLevel
 136          */
 137         protected $mTrxShortId = '';
 138         /**
 139          * The UNIX time that the transaction started. Callers can assume that if
 140          * snapshot isolation is used, then the data is *at least* up to date to that
 141          * point (possibly more up-to-date since the first SELECT defines the snapshot).
 142          *
 143          * @var float|null
 144          * @see Database::mTrxLevel
 145          */
 146         private $mTrxTimestamp = null;
 147         /** @var float Lag estimate at the time of BEGIN */
 148         private $mTrxReplicaLag = null;
 149         /**
 150          * Remembers the function name given for starting the most recent transaction via begin().
 151          * Used to provide additional context for error reporting.
 152          *
 153          * @var string
 154          * @see Database::mTrxLevel
 155          */
 156         private $mTrxFname = null;
 157         /**
 158          * Record if possible write queries were done in the last transaction started
 159          *
 160          * @var bool
 161          * @see Database::mTrxLevel
 162          */
 163         private $mTrxDoneWrites = false;
 164         /**
 165          * Record if the current transaction was started implicitly due to DBO_TRX being set.
 166          *
 167          * @var bool
 168          * @see Database::mTrxLevel
 169          */
 170         private $mTrxAutomatic = false;
 171         /**
 172          * Array of levels of atomicity within transactions
 173          *
 174          * @var array
 175          */
 176         private $mTrxAtomicLevels = [];
 177         /**
 178          * Record if the current transaction was started implicitly by Database::startAtomic
 179          *
 180          * @var bool
 181          */
 182         private $mTrxAutomaticAtomic = false;
 183         /**
 184          * Track the write query callers of the current transaction
 185          *
 186          * @var string[]
 187          */
 188         private $mTrxWriteCallers = [];
 189         /**
 190          * @var float Seconds spent in write queries for the current transaction
 191          */
 192         private $mTrxWriteDuration = 0.0;
 193         /**
 194          * @var integer Number of write queries for the current transaction
 195          */
 196         private $mTrxWriteQueryCount = 0;
 197         /**
 198          * @var float Like mTrxWriteQueryCount but excludes lock-bound, easy to replicate, queries
 199          */
 200         private $mTrxWriteAdjDuration = 0.0;
 201         /**
 202          * @var integer Number of write queries counted in mTrxWriteAdjDuration
 203          */
 204         private $mTrxWriteAdjQueryCount = 0;
 205         /**
 206          * @var float RTT time estimate
 207          */
 208         private $mRTTEstimate = 0.0;
 209
 210         /** @var array Map of (name => 1) for locks obtained via lock() */
 211         private $mNamedLocksHeld = [];
 212         /** @var array Map of (table name => 1) for TEMPORARY tables */
 213         protected $mSessionTempTables = [];
 214
 215         /** @var IDatabase|null Lazy handle to the master DB this server replicates from */
 216         private $lazyMasterHandle;
 217
 218         /** @var float UNIX timestamp */
 219         protected $lastPing = 0.0;
 220
 221         /** @var int[] Prior mFlags values */
 222         private $priorFlags = [];
 223
 224         /** @var object|string Class name or object With profileIn/profileOut methods */
 225         protected $profiler;
 226         /** @var TransactionProfiler */
 227         protected $trxProfiler;
 228
 229         /**
 230          * Constructor and database handle and attempt to connect to the DB server
 231          *
 232          * IDatabase classes should not be constructed directly in external
 233          * code. Database::factory() should be used instead.
 234          *
 235          * @param array $params Parameters passed from Database::factory()
 236          */
 237         function __construct( array $params ) {
 238                 $server = $params['host'];
 239                 $user = $params['user'];
 240                 $password = $params['password'];
 241                 $dbName = $params['dbname'];
 242
 243                 $this->mSchema = $params['schema'];
 244                 $this->mTablePrefix = $params['tablePrefix'];
 245
 246                 $this->cliMode = $params['cliMode'];
 247                 // Agent name is added to SQL queries in a comment, so make sure it can't break out
 248                 $this->agent = str_replace( '/', '-', $params['agent'] );
 249
 250                 $this->mFlags = $params['flags'];
 251                 if ( $this->mFlags & self::DBO_DEFAULT ) {
 252                         if ( $this->cliMode ) {
 253                                 $this->mFlags &= ~self::DBO_TRX;
 254                         } else {
 255                                 $this->mFlags |= self::DBO_TRX;
 256                         }
 257                 }
 258
 259                 $this->mSessionVars = $params['variables'];
 260
 261                 $this->srvCache = isset( $params['srvCache'] )
 262                         ? $params['srvCache']
 263                         : new HashBagOStuff();
 264
 265                 $this->profiler = $params['profiler'];
 266                 $this->trxProfiler = $params['trxProfiler'];
 267                 $this->connLogger = $params['connLogger'];
 268                 $this->queryLogger = $params['queryLogger'];
 269                 $this->errorLogger = $params['errorLogger'];
 270
 271                 // Set initial dummy domain until open() sets the final DB/prefix
 272                 $this->currentDomain = DatabaseDomain::newUnspecified();
 273
 274                 if ( $user ) {
 275                         $this->open( $server, $user, $password, $dbName );
 276                 } elseif ( $this->requiresDatabaseUser() ) {
 277                         throw new InvalidArgumentException( "No database user provided." );
 278                 }
 279
 280                 // Set the domain object after open() sets the relevant fields
 281                 if ( $this->mDBname != '' ) {
 282                         // Domains with server scope but a table prefix are not used by IDatabase classes
 283                         $this->currentDomain = new DatabaseDomain( $this->mDBname, null, $this->mTablePrefix );
 284                 }
 285         }
 286
 287         /**
 288          * Construct a Database subclass instance given a database type and parameters
 289          *
 290          * This also connects to the database immediately upon object construction
 291          *
 292          * @param string $dbType A possible DB type (sqlite, mysql, postgres)
 293          * @param array $p Parameter map with keys:
 294          *   - host : The hostname of the DB server
 295          *   - user : The name of the database user the client operates under
 296          *   - password : The password for the database user
 297          *   - dbname : The name of the database to use where queries do not specify one.
 298          *      The database must exist or an error might be thrown. Setting this to the empty string
 299          *      will avoid any such errors and make the handle have no implicit database scope. This is
 300          *      useful for queries like SHOW STATUS, CREATE DATABASE, or DROP DATABASE. Note that a
 301          *      "database" in Postgres is rougly equivalent to an entire MySQL server. This the domain
 302          *      in which user names and such are defined, e.g. users are database-specific in Postgres.
 303          *   - schema : The database schema to use (if supported). A "schema" in Postgres is roughly
 304          *      equivalent to a "database" in MySQL. Note that MySQL and SQLite do not use schemas.
 305          *   - tablePrefix : Optional table prefix that is implicitly added on to all table names
 306          *      recognized in queries. This can be used in place of schemas for handle site farms.
 307          *   - flags : Optional bitfield of DBO_* constants that define connection, protocol,
 308          *      buffering, and transaction behavior. It is STRONGLY adviced to leave the DBO_DEFAULT
 309          *      flag in place UNLESS this this database simply acts as a key/value store.
 310          *   - driver: Optional name of a specific DB client driver. For MySQL, there is the old
 311          *      'mysql' driver and the newer 'mysqli' driver.
 312          *   - variables: Optional map of session variables to set after connecting. This can be
 313          *      used to adjust lock timeouts or encoding modes and the like.
 314          *   - connLogger: Optional PSR-3 logger interface instance.
 315          *   - queryLogger: Optional PSR-3 logger interface instance.
 316          *   - profiler: Optional class name or object with profileIn()/profileOut() methods.
 317          *      These will be called in query(), using a simplified version of the SQL that also
 318          *      includes the agent as a SQL comment.
 319          *   - trxProfiler: Optional TransactionProfiler instance.
 320          *   - errorLogger: Optional callback that takes an Exception and logs it.
 321          *   - cliMode: Whether to consider the execution context that of a CLI script.
 322          *   - agent: Optional name used to identify the end-user in query profiling/logging.
 323          *   - srvCache: Optional BagOStuff instance to an APC-style cache.
 324          * @return Database|null If the database driver or extension cannot be found
 325          * @throws InvalidArgumentException If the database driver or extension cannot be found
 326          * @since 1.18
 327          */
 328         final public static function factory( $dbType, $p = [] ) {
 329                 static $canonicalDBTypes = [
 330                         'mysql' => [ 'mysqli', 'mysql' ],
 331                         'postgres' => [],
 332                         'sqlite' => [],
 333                         'oracle' => [],
 334                         'mssql' => [],
 335                 ];
 336
 337                 $driver = false;
 338                 $dbType = strtolower( $dbType );
 339                 if ( isset( $canonicalDBTypes[$dbType] ) && $canonicalDBTypes[$dbType] ) {
 340                         $possibleDrivers = $canonicalDBTypes[$dbType];
 341                         if ( !empty( $p['driver'] ) ) {
 342                                 if ( in_array( $p['driver'], $possibleDrivers ) ) {
 343                                         $driver = $p['driver'];
 344                                 } else {
 345                                         throw new InvalidArgumentException( __METHOD__ .
 346                                                 " type '$dbType' does not support driver '{$p['driver']}'" );
 347                                 }
 348                         } else {
 349                                 foreach ( $possibleDrivers as $posDriver ) {
 350                                         if ( extension_loaded( $posDriver ) ) {
 351                                                 $driver = $posDriver;
 352                                                 break;
 353                                         }
 354                                 }
 355                         }
 356                 } else {
 357                         $driver = $dbType;
 358                 }
 359                 if ( $driver === false || $driver === '' ) {
 360                         throw new InvalidArgumentException( __METHOD__ .
 361                                 " no viable database extension found for type '$dbType'" );
 362                 }
 363
 364                 $class = 'Database' . ucfirst( $driver );
 365                 if ( class_exists( $class ) && is_subclass_of( $class, 'IDatabase' ) ) {
 366                         // Resolve some defaults for b/c
 367                         $p['host'] = isset( $p['host'] ) ? $p['host'] : false;
 368                         $p['user'] = isset( $p['user'] ) ? $p['user'] : false;
 369                         $p['password'] = isset( $p['password'] ) ? $p['password'] : false;
 370                         $p['dbname'] = isset( $p['dbname'] ) ? $p['dbname'] : false;
 371                         $p['flags'] = isset( $p['flags'] ) ? $p['flags'] : 0;
 372                         $p['variables'] = isset( $p['variables'] ) ? $p['variables'] : [];
 373                         $p['tablePrefix'] = isset( $p['tablePrefix'] ) ? $p['tablePrefix'] : '';
 374                         $p['schema'] = isset( $p['schema'] ) ? $p['schema'] : '';
 375                         $p['cliMode'] = isset( $p['cliMode'] ) ? $p['cliMode'] : ( PHP_SAPI === 'cli' );
 376                         $p['agent'] = isset( $p['agent'] ) ? $p['agent'] : '';
 377                         if ( !isset( $p['connLogger'] ) ) {
 378                                 $p['connLogger'] = new \Psr\Log\NullLogger();
 379                         }
 380                         if ( !isset( $p['queryLogger'] ) ) {
 381                                 $p['queryLogger'] = new \Psr\Log\NullLogger();
 382                         }
 383                         $p['profiler'] = isset( $p['profiler'] ) ? $p['profiler'] : null;
 384                         if ( !isset( $p['trxProfiler'] ) ) {
 385                                 $p['trxProfiler'] = new TransactionProfiler();
 386                         }
 387                         if ( !isset( $p['errorLogger'] ) ) {
 388                                 $p['errorLogger'] = function ( Exception $e ) {
 389                                         trigger_error( get_class( $e ) . ': ' . $e->getMessage(), E_USER_WARNING );
 390                                 };
 391                         }
 392
 393                         $conn = new $class( $p );
 394                 } else {
 395                         $conn = null;
 396                 }
 397
 398                 return $conn;
 399         }
 400
 401         public function setLogger( LoggerInterface $logger ) {
 402                 $this->queryLogger = $logger;
 403         }
 404
 405         public function getServerInfo() {
 406                 return $this->getServerVersion();
 407         }
 408
 409         public function bufferResults( $buffer = null ) {
 410                 $res = !$this->getFlag( self::DBO_NOBUFFER );
 411                 if ( $buffer !== null ) {
 412                         $buffer
 413                                 ? $this->clearFlag( self::DBO_NOBUFFER )
 414                                 : $this->setFlag( self::DBO_NOBUFFER );
 415                 }
 416
 417                 return $res;
 418         }
 419
 420         /**
 421          * Turns on (false) or off (true) the automatic generation and sending
 422          * of a "we're sorry, but there has been a database error" page on
 423          * database errors. Default is on (false). When turned off, the
 424          * code should use lastErrno() and lastError() to handle the
 425          * situation as appropriate.
 426          *
 427          * Do not use this function outside of the Database classes.
 428          *
 429          * @param null|bool $ignoreErrors
 430          * @return bool The previous value of the flag.
 431          */
 432         protected function ignoreErrors( $ignoreErrors = null ) {
 433                 $res = $this->getFlag( self::DBO_IGNORE );
 434                 if ( $ignoreErrors !== null ) {
 435                         $ignoreErrors
 436                                 ? $this->setFlag( self::DBO_IGNORE )
 437                                 : $this->clearFlag( self::DBO_IGNORE );
 438                 }
 439
 440                 return $res;
 441         }
 442
 443         public function trxLevel() {
 444                 return $this->mTrxLevel;
 445         }
 446
 447         public function trxTimestamp() {
 448                 return $this->mTrxLevel ? $this->mTrxTimestamp : null;
 449         }
 450
 451         public function tablePrefix( $prefix = null ) {
 452                 $old = $this->mTablePrefix;
 453                 if ( $prefix !== null ) {
 454                         $this->mTablePrefix = $prefix;
 455                         $this->currentDomain = ( $this->mDBname != '' )
 456                                 ? new DatabaseDomain( $this->mDBname, null, $this->mTablePrefix )
 457                                 : DatabaseDomain::newUnspecified();
 458                 }
 459
 460                 return $old;
 461         }
 462
 463         public function dbSchema( $schema = null ) {
 464                 $old = $this->mSchema;
 465                 if ( $schema !== null ) {
 466                         $this->mSchema = $schema;
 467                 }
 468
 469                 return $old;
 470         }
 471
 472         public function getLBInfo( $name = null ) {
 473                 if ( is_null( $name ) ) {
 474                         return $this->mLBInfo;
 475                 } else {
 476                         if ( array_key_exists( $name, $this->mLBInfo ) ) {
 477                                 return $this->mLBInfo[$name];
 478                         } else {
 479                                 return null;
 480                         }
 481                 }
 482         }
 483
 484         public function setLBInfo( $name, $value = null ) {
 485                 if ( is_null( $value ) ) {
 486                         $this->mLBInfo = $name;
 487                 } else {
 488                         $this->mLBInfo[$name] = $value;
 489                 }
 490         }
 491
 492         public function setLazyMasterHandle( IDatabase $conn ) {
 493                 $this->lazyMasterHandle = $conn;
 494         }
 495
 496         /**
 497          * @return IDatabase|null
 498          * @see setLazyMasterHandle()
 499          * @since 1.27
 500          */
 501         protected function getLazyMasterHandle() {
 502                 return $this->lazyMasterHandle;
 503         }
 504
 505         public function implicitGroupby() {
 506                 return true;
 507         }
 508
 509         public function implicitOrderby() {
 510                 return true;
 511         }
 512
 513         public function lastQuery() {
 514                 return $this->mLastQuery;
 515         }
 516
 517         public function doneWrites() {
 518                 return (bool)$this->mLastWriteTime;
 519         }
 520
 521         public function lastDoneWrites() {
 522                 return $this->mLastWriteTime ?: false;
 523         }
 524
 525         public function writesPending() {
 526                 return $this->mTrxLevel && $this->mTrxDoneWrites;
 527         }
 528
 529         public function writesOrCallbacksPending() {
 530                 return $this->mTrxLevel && (
 531                         $this->mTrxDoneWrites || $this->mTrxIdleCallbacks || $this->mTrxPreCommitCallbacks
 532                 );
 533         }
 534
 535         public function pendingWriteQueryDuration( $type = self::ESTIMATE_TOTAL ) {
 536                 if ( !$this->mTrxLevel ) {
 537                         return false;
 538                 } elseif ( !$this->mTrxDoneWrites ) {
 539                         return 0.0;
 540                 }
 541
 542                 switch ( $type ) {
 543                         case self::ESTIMATE_DB_APPLY:
 544                                 $this->ping( $rtt );
 545                                 $rttAdjTotal = $this->mTrxWriteAdjQueryCount * $rtt;
 546                                 $applyTime = max( $this->mTrxWriteAdjDuration - $rttAdjTotal, 0 );
 547                                 // For omitted queries, make them count as something at least
 548                                 $omitted = $this->mTrxWriteQueryCount - $this->mTrxWriteAdjQueryCount;
 549                                 $applyTime += self::TINY_WRITE_SEC * $omitted;
 550
 551                                 return $applyTime;
 552                         default: // everything
 553                                 return $this->mTrxWriteDuration;
 554                 }
 555         }
 556
 557         public function pendingWriteCallers() {
 558                 return $this->mTrxLevel ? $this->mTrxWriteCallers : [];
 559         }
 560
 561         protected function pendingWriteAndCallbackCallers() {
 562                 if ( !$this->mTrxLevel ) {
 563                         return [];
 564                 }
 565
 566                 $fnames = $this->mTrxWriteCallers;
 567                 foreach ( [
 568                         $this->mTrxIdleCallbacks,
 569                         $this->mTrxPreCommitCallbacks,
 570                         $this->mTrxEndCallbacks
 571                 ] as $callbacks ) {
 572                         foreach ( $callbacks as $callback ) {
 573                                 $fnames[] = $callback[1];
 574                         }
 575                 }
 576
 577                 return $fnames;
 578         }
 579
 580         public function isOpen() {
 581                 return $this->mOpened;
 582         }
 583
 584         public function setFlag( $flag, $remember = self::REMEMBER_NOTHING ) {
 585                 if ( $remember === self::REMEMBER_PRIOR ) {
 586                         array_push( $this->priorFlags, $this->mFlags );
 587                 }
 588                 $this->mFlags |= $flag;
 589         }
 590
 591         public function clearFlag( $flag, $remember = self::REMEMBER_NOTHING ) {
 592                 if ( $remember === self::REMEMBER_PRIOR ) {
 593                         array_push( $this->priorFlags, $this->mFlags );
 594                 }
 595                 $this->mFlags &= ~$flag;
 596         }
 597
 598         public function restoreFlags( $state = self::RESTORE_PRIOR ) {
 599                 if ( !$this->priorFlags ) {
 600                         return;
 601                 }
 602
 603                 if ( $state === self::RESTORE_INITIAL ) {
 604                         $this->mFlags = reset( $this->priorFlags );
 605                         $this->priorFlags = [];
 606                 } else {
 607                         $this->mFlags = array_pop( $this->priorFlags );
 608                 }
 609         }
 610
 611         public function getFlag( $flag ) {
 612                 return !!( $this->mFlags & $flag );
 613         }
 614
 615         /**
 616          * @param string $name Class field name
 617          * @return mixed
 618          * @deprecated Since 1.28
 619          */
 620         public function getProperty( $name ) {
 621                 return $this->$name;
 622         }
 623
 624         public function getDomainID() {
 625                 return $this->currentDomain->getId();
 626         }
 627
 628         final public function getWikiID() {
 629                 return $this->getDomainID();
 630         }
 631
 632         /**
 633          * Get information about an index into an object
 634          * @param string $table Table name
 635          * @param string $index Index name
 636          * @param string $fname Calling function name
 637          * @return mixed Database-specific index description class or false if the index does not exist
 638          */
 639         abstract function indexInfo( $table, $index, $fname = __METHOD__ );
 640
 641         /**
 642          * Wrapper for addslashes()
 643          *
 644          * @param string $s String to be slashed.
 645          * @return string Slashed string.
 646          */
 647         abstract function strencode( $s );
 648
 649         protected function installErrorHandler() {
 650                 $this->mPHPError = false;
 651                 $this->htmlErrors = ini_set( 'html_errors', '0' );
 652                 set_error_handler( [ $this, 'connectionErrorLogger' ] );
 653         }
 654
 655         /**
 656          * @return bool|string
 657          */
 658         protected function restoreErrorHandler() {
 659                 restore_error_handler();
 660                 if ( $this->htmlErrors !== false ) {
 661                         ini_set( 'html_errors', $this->htmlErrors );
 662                 }
 663
 664                 return $this->getLastPHPError();
 665         }
 666
 667         /**
 668          * @return string|bool Last PHP error for this DB (typically connection errors)
 669          */
 670         protected function getLastPHPError() {
 671                 if ( $this->mPHPError ) {
 672                         $error = preg_replace( '!\[<a.*</a>\]!', '', $this->mPHPError );
 673                         $error = preg_replace( '!^.*?:\s?(.*)$!', '$1', $error );
 674
 675                         return $error;
 676                 }
 677
 678                 return false;
 679         }
 680
 681         /**
 682          * This method should not be used outside of Database classes
 683          *
 684          * @param int $errno
 685          * @param string $errstr
 686          */
 687         public function connectionErrorLogger( $errno, $errstr ) {
 688                 $this->mPHPError = $errstr;
 689         }
 690
 691         /**
 692          * Create a log context to pass to PSR-3 logger functions.
 693          *
 694          * @param array $extras Additional data to add to context
 695          * @return array
 696          */
 697         protected function getLogContext( array $extras = [] ) {
 698                 return array_merge(
 699                         [
 700                                 'db_server' => $this->mServer,
 701                                 'db_name' => $this->mDBname,
 702                                 'db_user' => $this->mUser,
 703                         ],
 704                         $extras
 705                 );
 706         }
 707
 708         public function close() {
 709                 if ( $this->mConn ) {
 710                         if ( $this->trxLevel() ) {
 711                                 $this->commit( __METHOD__, self::FLUSHING_INTERNAL );
 712                         }
 713
 714                         $closed = $this->closeConnection();
 715                         $this->mConn = false;
 716                 } elseif ( $this->mTrxIdleCallbacks || $this->mTrxEndCallbacks ) { // sanity
 717                         throw new RuntimeException( "Transaction callbacks still pending." );
 718                 } else {
 719                         $closed = true;
 720                 }
 721                 $this->mOpened = false;
 722
 723                 return $closed;
 724         }
 725
 726         /**
 727          * Make sure isOpen() returns true as a sanity check
 728          *
 729          * @throws DBUnexpectedError
 730          */
 731         protected function assertOpen() {
 732                 if ( !$this->isOpen() ) {
 733                         throw new DBUnexpectedError( $this, "DB connection was already closed." );
 734                 }
 735         }
 736
 737         /**
 738          * Closes underlying database connection
 739          * @since 1.20
 740          * @return bool Whether connection was closed successfully
 741          */
 742         abstract protected function closeConnection();
 743
 744         public function reportConnectionError( $error = 'Unknown error' ) {
 745                 $myError = $this->lastError();
 746                 if ( $myError ) {
 747                         $error = $myError;
 748                 }
 749
 750                 # New method
 751                 throw new DBConnectionError( $this, $error );
 752         }
 753
 754         /**
 755          * The DBMS-dependent part of query()
 756          *
 757          * @param string $sql SQL query.
 758          * @return ResultWrapper|bool Result object to feed to fetchObject,
 759          *   fetchRow, ...; or false on failure
 760          */
 761         abstract protected function doQuery( $sql );
 762
 763         /**
 764          * Determine whether a query writes to the DB.
 765          * Should return true if unsure.
 766          *
 767          * @param string $sql
 768          * @return bool
 769          */
 770         protected function isWriteQuery( $sql ) {
 771                 return !preg_match(
 772                         '/^(?:SELECT|BEGIN|ROLLBACK|COMMIT|SET|SHOW|EXPLAIN|\(SELECT)\b/i', $sql );
 773         }
 774
 775         /**
 776          * @param $sql
 777          * @return string|null
 778          */
 779         protected function getQueryVerb( $sql ) {
 780                 return preg_match( '/^\s*([a-z]+)/i', $sql, $m ) ? strtoupper( $m[1] ) : null;
 781         }
 782
 783         /**
 784          * Determine whether a SQL statement is sensitive to isolation level.
 785          * A SQL statement is considered transactable if its result could vary
 786          * depending on the transaction isolation level. Operational commands
 787          * such as 'SET' and 'SHOW' are not considered to be transactable.
 788          *
 789          * @param string $sql
 790          * @return bool
 791          */
 792         protected function isTransactableQuery( $sql ) {
 793                 return !in_array(
 794                         $this->getQueryVerb( $sql ),
 795                         [ 'BEGIN', 'COMMIT', 'ROLLBACK', 'SHOW', 'SET', 'CREATE', 'ALTER' ],
 796                         true
 797                 );
 798         }
 799
 800         /**
 801          * @param string $sql A SQL query
 802          * @return bool Whether $sql is SQL for creating/dropping a new TEMPORARY table
 803          */
 804         protected function registerTempTableOperation( $sql ) {
 805                 if ( preg_match(
 806                         '/^CREATE\s+TEMPORARY\s+TABLE\s+(?:IF\s+NOT\s+EXISTS\s+)?[`"\']?(\w+)[`"\']?/i',
 807                         $sql,
 808                         $matches
 809                 ) ) {
 810                         $this->mSessionTempTables[$matches[1]] = 1;
 811
 812                         return true;
 813                 } elseif ( preg_match(
 814                         '/^DROP\s+(?:TEMPORARY\s+)?TABLE\s+(?:IF\s+EXISTS\s+)?[`"\']?(\w+)[`"\']?/i',
 815                         $sql,
 816                         $matches
 817                 ) ) {
 818                         unset( $this->mSessionTempTables[$matches[1]] );
 819
 820                         return true;
 821                 } elseif ( preg_match(
 822                         '/^(?:INSERT\s+(?:\w+\s+)?INTO|UPDATE|DELETE\s+FROM)\s+[`"\']?(\w+)[`"\']?/i',
 823                         $sql,
 824                         $matches
 825                 ) ) {
 826                         return isset( $this->mSessionTempTables[$matches[1]] );
 827                 }
 828
 829                 return false;
 830         }
 831
 832         public function query( $sql, $fname = __METHOD__, $tempIgnore = false ) {
 833                 $priorWritesPending = $this->writesOrCallbacksPending();
 834                 $this->mLastQuery = $sql;
 835
 836                 $isWrite = $this->isWriteQuery( $sql ) && !$this->registerTempTableOperation( $sql );
 837                 if ( $isWrite ) {
 838                         $reason = $this->getReadOnlyReason();
 839                         if ( $reason !== false ) {
 840                                 throw new DBReadOnlyError( $this, "Database is read-only: $reason" );
 841                         }
 842                         # Set a flag indicating that writes have been done
 843                         $this->mLastWriteTime = microtime( true );
 844                 }
 845
 846                 // Add trace comment to the begin of the sql string, right after the operator.
 847                 // Or, for one-word queries (like "BEGIN" or COMMIT") add it to the end (bug 42598)
 848                 $commentedSql = preg_replace( '/\s|$/', " /* $fname {$this->agent} */ ", $sql, 1 );
 849
 850                 # Start implicit transactions that wrap the request if DBO_TRX is enabled
 851                 if ( !$this->mTrxLevel && $this->getFlag( self::DBO_TRX )
 852                         && $this->isTransactableQuery( $sql )
 853                 ) {
 854                         $this->begin( __METHOD__ . " ($fname)", self::TRANSACTION_INTERNAL );
 855                         $this->mTrxAutomatic = true;
 856                 }
 857
 858                 # Keep track of whether the transaction has write queries pending
 859                 if ( $this->mTrxLevel && !$this->mTrxDoneWrites && $isWrite ) {
 860                         $this->mTrxDoneWrites = true;
 861                         $this->trxProfiler->transactionWritingIn(
 862                                 $this->mServer, $this->mDBname, $this->mTrxShortId );
 863                 }
 864
 865                 if ( $this->getFlag( self::DBO_DEBUG ) ) {
 866                         $this->queryLogger->debug( "{$this->mDBname} {$commentedSql}" );
 867                 }
 868
 869                 # Avoid fatals if close() was called
 870                 $this->assertOpen();
 871
 872                 # Send the query to the server
 873                 $ret = $this->doProfiledQuery( $sql, $commentedSql, $isWrite, $fname );
 874
 875                 # Try reconnecting if the connection was lost
 876                 if ( false === $ret && $this->wasErrorReissuable() ) {
 877                         $recoverable = $this->canRecoverFromDisconnect( $sql, $priorWritesPending );
 878                         # Stash the last error values before anything might clear them
 879                         $lastError = $this->lastError();
 880                         $lastErrno = $this->lastErrno();
 881                         # Update state tracking to reflect transaction loss due to disconnection
 882                         $this->handleSessionLoss();
 883                         if ( $this->reconnect() ) {
 884                                 $msg = __METHOD__ . ": lost connection to {$this->getServer()}; reconnected";
 885                                 $this->connLogger->warning( $msg );
 886                                 $this->queryLogger->warning(
 887                                         "$msg:\n" . ( new RuntimeException() )->getTraceAsString() );
 888
 889                                 if ( !$recoverable ) {
 890                                         # Callers may catch the exception and continue to use the DB
 891                                         $this->reportQueryError( $lastError, $lastErrno, $sql, $fname );
 892                                 } else {
 893                                         # Should be safe to silently retry the query
 894                                         $ret = $this->doProfiledQuery( $sql, $commentedSql, $isWrite, $fname );
 895                                 }
 896                         } else {
 897                                 $msg = __METHOD__ . ": lost connection to {$this->getServer()} permanently";
 898                                 $this->connLogger->error( $msg );
 899                         }
 900                 }
 901
 902                 if ( false === $ret ) {
 903                         # Deadlocks cause the entire transaction to abort, not just the statement.
 904                         # https://dev.mysql.com/doc/refman/5.7/en/innodb-error-handling.html
 905                         # https://www.postgresql.org/docs/9.1/static/explicit-locking.html
 906                         if ( $this->wasDeadlock() ) {
 907                                 if ( $this->explicitTrxActive() || $priorWritesPending ) {
 908                                         $tempIgnore = false; // not recoverable
 909                                 }
 910                                 # Update state tracking to reflect transaction loss
 911                                 $this->handleSessionLoss();
 912                         }
 913
 914                         $this->reportQueryError(
 915                                 $this->lastError(), $this->lastErrno(), $sql, $fname, $tempIgnore );
 916                 }
 917
 918                 $res = $this->resultObject( $ret );
 919
 920                 return $res;
 921         }
 922
 923         private function doProfiledQuery( $sql, $commentedSql, $isWrite, $fname ) {
 924                 $isMaster = !is_null( $this->getLBInfo( 'master' ) );
 925                 # generalizeSQL() will probably cut down the query to reasonable
 926                 # logging size most of the time. The substr is really just a sanity check.
 927                 if ( $isMaster ) {
 928                         $queryProf = 'query-m: ' . substr( self::generalizeSQL( $sql ), 0, 255 );
 929                 } else {
 930                         $queryProf = 'query: ' . substr( self::generalizeSQL( $sql ), 0, 255 );
 931                 }
 932
 933                 # Include query transaction state
 934                 $queryProf .= $this->mTrxShortId ? " [TRX#{$this->mTrxShortId}]" : "";
 935
 936                 $startTime = microtime( true );
 937                 if ( $this->profiler ) {
 938                         call_user_func( [ $this->profiler, 'profileIn' ], $queryProf );
 939                 }
 940                 $ret = $this->doQuery( $commentedSql );
 941                 if ( $this->profiler ) {
 942                         call_user_func( [ $this->profiler, 'profileOut' ], $queryProf );
 943                 }
 944                 $queryRuntime = max( microtime( true ) - $startTime, 0.0 );
 945
 946                 unset( $queryProfSection ); // profile out (if set)
 947
 948                 if ( $ret !== false ) {
 949                         $this->lastPing = $startTime;
 950                         if ( $isWrite && $this->mTrxLevel ) {
 951                                 $this->updateTrxWriteQueryTime( $sql, $queryRuntime );
 952                                 $this->mTrxWriteCallers[] = $fname;
 953                         }
 954                 }
 955
 956                 if ( $sql === self::PING_QUERY ) {
 957                         $this->mRTTEstimate = $queryRuntime;
 958                 }
 959
 960                 $this->trxProfiler->recordQueryCompletion(
 961                         $queryProf, $startTime, $isWrite, $this->affectedRows()
 962                 );
 963                 $this->queryLogger->debug( $sql, [
 964                         'method' => $fname,
 965                         'master' => $isMaster,
 966                         'runtime' => $queryRuntime,
 967                 ] );
 968
 969                 return $ret;
 970         }
 971
 972         /**
 973          * Update the estimated run-time of a query, not counting large row lock times
 974          *
 975          * LoadBalancer can be set to rollback transactions that will create huge replication
 976          * lag. It bases this estimate off of pendingWriteQueryDuration(). Certain simple
 977          * queries, like inserting a row can take a long time due to row locking. This method
 978          * uses some simple heuristics to discount those cases.
 979          *
 980          * @param string $sql A SQL write query
 981          * @param float $runtime Total runtime, including RTT
 982          */
 983         private function updateTrxWriteQueryTime( $sql, $runtime ) {
 984                 // Whether this is indicative of replica DB runtime (except for RBR or ws_repl)
 985                 $indicativeOfReplicaRuntime = true;
 986                 if ( $runtime > self::SLOW_WRITE_SEC ) {
 987                         $verb = $this->getQueryVerb( $sql );
 988                         // insert(), upsert(), replace() are fast unless bulky in size or blocked on locks
 989                         if ( $verb === 'INSERT' ) {
 990                                 $indicativeOfReplicaRuntime = $this->affectedRows() > self::SMALL_WRITE_ROWS;
 991                         } elseif ( $verb === 'REPLACE' ) {
 992                                 $indicativeOfReplicaRuntime = $this->affectedRows() > self::SMALL_WRITE_ROWS / 2;
 993                         }
 994                 }
 995
 996                 $this->mTrxWriteDuration += $runtime;
 997                 $this->mTrxWriteQueryCount += 1;
 998                 if ( $indicativeOfReplicaRuntime ) {
 999                         $this->mTrxWriteAdjDuration += $runtime;
1000                         $this->mTrxWriteAdjQueryCount += 1;
1001                 }
1002         }
1003
1004         private function canRecoverFromDisconnect( $sql, $priorWritesPending ) {
1005                 # Transaction dropped; this can mean lost writes, or REPEATABLE-READ snapshots.
1006                 # Dropped connections also mean that named locks are automatically released.
1007                 # Only allow error suppression in autocommit mode or when the lost transaction
1008                 # didn't matter anyway (aside from DBO_TRX snapshot loss).
1009                 if ( $this->mNamedLocksHeld ) {
1010                         return false; // possible critical section violation
1011                 } elseif ( $sql === 'COMMIT' ) {
1012                         return !$priorWritesPending; // nothing written anyway? (T127428)
1013                 } elseif ( $sql === 'ROLLBACK' ) {
1014                         return true; // transaction lost...which is also what was requested :)
1015                 } elseif ( $this->explicitTrxActive() ) {
1016                         return false; // don't drop atomocity
1017                 } elseif ( $priorWritesPending ) {
1018                         return false; // prior writes lost from implicit transaction
1019                 }
1020
1021                 return true;
1022         }
1023
1024         private function handleSessionLoss() {
1025                 $this->mTrxLevel = 0;
1026                 $this->mTrxIdleCallbacks = []; // bug 65263
1027                 $this->mTrxPreCommitCallbacks = []; // bug 65263
1028                 $this->mSessionTempTables = [];
1029                 $this->mNamedLocksHeld = [];
1030                 try {
1031                         // Handle callbacks in mTrxEndCallbacks
1032                         $this->runOnTransactionIdleCallbacks( self::TRIGGER_ROLLBACK );
1033                         $this->runTransactionListenerCallbacks( self::TRIGGER_ROLLBACK );
1034                         return null;
1035                 } catch ( Exception $e ) {
1036                         // Already logged; move on...
1037                         return $e;
1038                 }
1039         }
1040
1041         public function reportQueryError( $error, $errno, $sql, $fname, $tempIgnore = false ) {
1042                 if ( $this->ignoreErrors() || $tempIgnore ) {
1043                         $this->queryLogger->debug( "SQL ERROR (ignored): $error\n" );
1044                 } else {
1045                         $sql1line = mb_substr( str_replace( "\n", "\\n", $sql ), 0, 5 * 1024 );
1046                         $this->queryLogger->error(
1047                                 "{fname}\t{db_server}\t{errno}\t{error}\t{sql1line}",
1048                                 $this->getLogContext( [
1049                                         'method' => __METHOD__,
1050                                         'errno' => $errno,
1051                                         'error' => $error,
1052                                         'sql1line' => $sql1line,
1053                                         'fname' => $fname,
1054                                 ] )
1055                         );
1056                         $this->queryLogger->debug( "SQL ERROR: " . $error . "\n" );
1057                         throw new DBQueryError( $this, $error, $errno, $sql, $fname );
1058                 }
1059         }
1060
1061         public function freeResult( $res ) {
1062         }
1063
1064         public function selectField(
1065                 $table, $var, $cond = '', $fname = __METHOD__, $options = []
1066         ) {
1067                 if ( $var === '*' ) { // sanity
1068                         throw new DBUnexpectedError( $this, "Cannot use a * field: got '$var'" );
1069                 }
1070
1071                 if ( !is_array( $options ) ) {
1072                         $options = [ $options ];
1073                 }
1074
1075                 $options['LIMIT'] = 1;
1076
1077                 $res = $this->select( $table, $var, $cond, $fname, $options );
1078                 if ( $res === false || !$this->numRows( $res ) ) {
1079                         return false;
1080                 }
1081
1082                 $row = $this->fetchRow( $res );
1083
1084                 if ( $row !== false ) {
1085                         return reset( $row );
1086                 } else {
1087                         return false;
1088                 }
1089         }
1090
1091         public function selectFieldValues(
1092                 $table, $var, $cond = '', $fname = __METHOD__, $options = [], $join_conds = []
1093         ) {
1094                 if ( $var === '*' ) { // sanity
1095                         throw new DBUnexpectedError( $this, "Cannot use a * field" );
1096                 } elseif ( !is_string( $var ) ) { // sanity
1097                         throw new DBUnexpectedError( $this, "Cannot use an array of fields" );
1098                 }
1099
1100                 if ( !is_array( $options ) ) {
1101                         $options = [ $options ];
1102                 }
1103
1104                 $res = $this->select( $table, $var, $cond, $fname, $options, $join_conds );
1105                 if ( $res === false ) {
1106                         return false;
1107                 }
1108
1109                 $values = [];
1110                 foreach ( $res as $row ) {
1111                         $values[] = $row->$var;
1112                 }
1113
1114                 return $values;
1115         }
1116
1117         /**
1118          * Returns an optional USE INDEX clause to go after the table, and a
1119          * string to go at the end of the query.
1120          *
1121          * @param array $options Associative array of options to be turned into
1122          *   an SQL query, valid keys are listed in the function.
1123          * @return array
1124          * @see Database::select()
1125          */
1126         protected function makeSelectOptions( $options ) {
1127                 $preLimitTail = $postLimitTail = '';
1128                 $startOpts = '';
1129
1130                 $noKeyOptions = [];
1131
1132                 foreach ( $options as $key => $option ) {
1133                         if ( is_numeric( $key ) ) {
1134                                 $noKeyOptions[$option] = true;
1135                         }
1136                 }
1137
1138                 $preLimitTail .= $this->makeGroupByWithHaving( $options );
1139
1140                 $preLimitTail .= $this->makeOrderBy( $options );
1141
1142                 // if (isset($options['LIMIT'])) {
1143                 //      $tailOpts .= $this->limitResult('', $options['LIMIT'],
1144                 //              isset($options['OFFSET']) ? $options['OFFSET']
1145                 //              : false);
1146                 // }
1147
1148                 if ( isset( $noKeyOptions['FOR UPDATE'] ) ) {
1149                         $postLimitTail .= ' FOR UPDATE';
1150                 }
1151
1152                 if ( isset( $noKeyOptions['LOCK IN SHARE MODE'] ) ) {
1153                         $postLimitTail .= ' LOCK IN SHARE MODE';
1154                 }
1155
1156                 if ( isset( $noKeyOptions['DISTINCT'] ) || isset( $noKeyOptions['DISTINCTROW'] ) ) {
1157                         $startOpts .= 'DISTINCT';
1158                 }
1159
1160                 # Various MySQL extensions
1161                 if ( isset( $noKeyOptions['STRAIGHT_JOIN'] ) ) {
1162                         $startOpts .= ' /*! STRAIGHT_JOIN */';
1163                 }
1164
1165                 if ( isset( $noKeyOptions['HIGH_PRIORITY'] ) ) {
1166                         $startOpts .= ' HIGH_PRIORITY';
1167                 }
1168
1169                 if ( isset( $noKeyOptions['SQL_BIG_RESULT'] ) ) {
1170                         $startOpts .= ' SQL_BIG_RESULT';
1171                 }
1172
1173                 if ( isset( $noKeyOptions['SQL_BUFFER_RESULT'] ) ) {
1174                         $startOpts .= ' SQL_BUFFER_RESULT';
1175                 }
1176
1177                 if ( isset( $noKeyOptions['SQL_SMALL_RESULT'] ) ) {
1178                         $startOpts .= ' SQL_SMALL_RESULT';
1179                 }
1180
1181                 if ( isset( $noKeyOptions['SQL_CALC_FOUND_ROWS'] ) ) {
1182                         $startOpts .= ' SQL_CALC_FOUND_ROWS';
1183                 }
1184
1185                 if ( isset( $noKeyOptions['SQL_CACHE'] ) ) {
1186                         $startOpts .= ' SQL_CACHE';
1187                 }
1188
1189                 if ( isset( $noKeyOptions['SQL_NO_CACHE'] ) ) {
1190                         $startOpts .= ' SQL_NO_CACHE';
1191                 }
1192
1193                 if ( isset( $options['USE INDEX'] ) && is_string( $options['USE INDEX'] ) ) {
1194                         $useIndex = $this->useIndexClause( $options['USE INDEX'] );
1195                 } else {
1196                         $useIndex = '';
1197                 }
1198                 if ( isset( $options['IGNORE INDEX'] ) && is_string( $options['IGNORE INDEX'] ) ) {
1199                         $ignoreIndex = $this->ignoreIndexClause( $options['IGNORE INDEX'] );
1200                 } else {
1201                         $ignoreIndex = '';
1202                 }
1203
1204                 return [ $startOpts, $useIndex, $preLimitTail, $postLimitTail, $ignoreIndex ];
1205         }
1206
1207         /**
1208          * Returns an optional GROUP BY with an optional HAVING
1209          *
1210          * @param array $options Associative array of options
1211          * @return string
1212          * @see Database::select()
1213          * @since 1.21
1214          */
1215         protected function makeGroupByWithHaving( $options ) {
1216                 $sql = '';
1217                 if ( isset( $options['GROUP BY'] ) ) {
1218                         $gb = is_array( $options['GROUP BY'] )
1219                                 ? implode( ',', $options['GROUP BY'] )
1220                                 : $options['GROUP BY'];
1221                         $sql .= ' GROUP BY ' . $gb;
1222                 }
1223                 if ( isset( $options['HAVING'] ) ) {
1224                         $having = is_array( $options['HAVING'] )
1225                                 ? $this->makeList( $options['HAVING'], self::LIST_AND )
1226                                 : $options['HAVING'];
1227                         $sql .= ' HAVING ' . $having;
1228                 }
1229
1230                 return $sql;
1231         }
1232
1233         /**
1234          * Returns an optional ORDER BY
1235          *
1236          * @param array $options Associative array of options
1237          * @return string
1238          * @see Database::select()
1239          * @since 1.21
1240          */
1241         protected function makeOrderBy( $options ) {
1242                 if ( isset( $options['ORDER BY'] ) ) {
1243                         $ob = is_array( $options['ORDER BY'] )
1244                                 ? implode( ',', $options['ORDER BY'] )
1245                                 : $options['ORDER BY'];
1246
1247                         return ' ORDER BY ' . $ob;
1248                 }
1249
1250                 return '';
1251         }
1252
1253         public function select( $table, $vars, $conds = '', $fname = __METHOD__,
1254                 $options = [], $join_conds = [] ) {
1255                 $sql = $this->selectSQLText( $table, $vars, $conds, $fname, $options, $join_conds );
1256
1257                 return $this->query( $sql, $fname );
1258         }
1259
1260         public function selectSQLText( $table, $vars, $conds = '', $fname = __METHOD__,
1261                 $options = [], $join_conds = []
1262         ) {
1263                 if ( is_array( $vars ) ) {
1264                         $vars = implode( ',', $this->fieldNamesWithAlias( $vars ) );
1265                 }
1266
1267                 $options = (array)$options;
1268                 $useIndexes = ( isset( $options['USE INDEX'] ) && is_array( $options['USE INDEX'] ) )
1269                         ? $options['USE INDEX']
1270                         : [];
1271                 $ignoreIndexes = (
1272                         isset( $options['IGNORE INDEX'] ) &&
1273                         is_array( $options['IGNORE INDEX'] )
1274                 )
1275                         ? $options['IGNORE INDEX']
1276                         : [];
1277
1278                 if ( is_array( $table ) ) {
1279                         $from = ' FROM ' .
1280                                 $this->tableNamesWithIndexClauseOrJOIN(
1281                                         $table, $useIndexes, $ignoreIndexes, $join_conds );
1282                 } elseif ( $table != '' ) {
1283                         if ( $table[0] == ' ' ) {
1284                                 $from = ' FROM ' . $table;
1285                         } else {
1286                                 $from = ' FROM ' .
1287                                         $this->tableNamesWithIndexClauseOrJOIN(
1288                                                 [ $table ], $useIndexes, $ignoreIndexes, [] );
1289                         }
1290                 } else {
1291                         $from = '';
1292                 }
1293
1294                 list( $startOpts, $useIndex, $preLimitTail, $postLimitTail, $ignoreIndex ) =
1295                         $this->makeSelectOptions( $options );
1296
1297                 if ( !empty( $conds ) ) {
1298                         if ( is_array( $conds ) ) {
1299                                 $conds = $this->makeList( $conds, self::LIST_AND );
1300                         }
1301                         $sql = "SELECT $startOpts $vars $from $useIndex $ignoreIndex " .
1302                                 "WHERE $conds $preLimitTail";
1303                 } else {
1304                         $sql = "SELECT $startOpts $vars $from $useIndex $ignoreIndex $preLimitTail";
1305                 }
1306
1307                 if ( isset( $options['LIMIT'] ) ) {
1308                         $sql = $this->limitResult( $sql, $options['LIMIT'],
1309                                 isset( $options['OFFSET'] ) ? $options['OFFSET'] : false );
1310                 }
1311                 $sql = "$sql $postLimitTail";
1312
1313                 if ( isset( $options['EXPLAIN'] ) ) {
1314                         $sql = 'EXPLAIN ' . $sql;
1315                 }
1316
1317                 return $sql;
1318         }
1319
1320         public function selectRow( $table, $vars, $conds, $fname = __METHOD__,
1321                 $options = [], $join_conds = []
1322         ) {
1323                 $options = (array)$options;
1324                 $options['LIMIT'] = 1;
1325                 $res = $this->select( $table, $vars, $conds, $fname, $options, $join_conds );
1326
1327                 if ( $res === false ) {
1328                         return false;
1329                 }
1330
1331                 if ( !$this->numRows( $res ) ) {
1332                         return false;
1333                 }
1334
1335                 $obj = $this->fetchObject( $res );
1336
1337                 return $obj;
1338         }
1339
1340         public function estimateRowCount(
1341                 $table, $vars = '*', $conds = '', $fname = __METHOD__, $options = []
1342         ) {
1343                 $rows = 0;
1344                 $res = $this->select( $table, [ 'rowcount' => 'COUNT(*)' ], $conds, $fname, $options );
1345
1346                 if ( $res ) {
1347                         $row = $this->fetchRow( $res );
1348                         $rows = ( isset( $row['rowcount'] ) ) ? (int)$row['rowcount'] : 0;
1349                 }
1350
1351                 return $rows;
1352         }
1353
1354         public function selectRowCount(
1355                 $tables, $vars = '*', $conds = '', $fname = __METHOD__, $options = [], $join_conds = []
1356         ) {
1357                 $rows = 0;
1358                 $sql = $this->selectSQLText( $tables, '1', $conds, $fname, $options, $join_conds );
1359                 $res = $this->query( "SELECT COUNT(*) AS rowcount FROM ($sql) tmp_count", $fname );
1360
1361                 if ( $res ) {
1362                         $row = $this->fetchRow( $res );
1363                         $rows = ( isset( $row['rowcount'] ) ) ? (int)$row['rowcount'] : 0;
1364                 }
1365
1366                 return $rows;
1367         }
1368
1369         /**
1370          * Removes most variables from an SQL query and replaces them with X or N for numbers.
1371          * It's only slightly flawed. Don't use for anything important.
1372          *
1373          * @param string $sql A SQL Query
1374          *
1375          * @return string
1376          */
1377         protected static function generalizeSQL( $sql ) {
1378                 # This does the same as the regexp below would do, but in such a way
1379                 # as to avoid crashing php on some large strings.
1380                 # $sql = preg_replace( "/'([^\\\\']|\\\\.)*'|\"([^\\\\\"]|\\\\.)*\"/", "'X'", $sql );
1381
1382                 $sql = str_replace( "\\\\", '', $sql );
1383                 $sql = str_replace( "\\'", '', $sql );
1384                 $sql = str_replace( "\\\"", '', $sql );
1385                 $sql = preg_replace( "/'.*'/s", "'X'", $sql );
1386                 $sql = preg_replace( '/".*"/s', "'X'", $sql );
1387
1388                 # All newlines, tabs, etc replaced by single space
1389                 $sql = preg_replace( '/\s+/', ' ', $sql );
1390
1391                 # All numbers => N,
1392                 # except the ones surrounded by characters, e.g. l10n
1393                 $sql = preg_replace( '/-?\d+(,-?\d+)+/s', 'N,...,N', $sql );
1394                 $sql = preg_replace( '/(?<![a-zA-Z])-?\d+(?![a-zA-Z])/s', 'N', $sql );
1395
1396                 return $sql;
1397         }
1398
1399         public function fieldExists( $table, $field, $fname = __METHOD__ ) {
1400                 $info = $this->fieldInfo( $table, $field );
1401
1402                 return (bool)$info;
1403         }
1404
1405         public function indexExists( $table, $index, $fname = __METHOD__ ) {
1406                 if ( !$this->tableExists( $table ) ) {
1407                         return null;
1408                 }
1409
1410                 $info = $this->indexInfo( $table, $index, $fname );
1411                 if ( is_null( $info ) ) {
1412                         return null;
1413                 } else {
1414                         return $info !== false;
1415                 }
1416         }
1417
1418         public function tableExists( $table, $fname = __METHOD__ ) {
1419                 $tableRaw = $this->tableName( $table, 'raw' );
1420                 if ( isset( $this->mSessionTempTables[$tableRaw] ) ) {
1421                         return true; // already known to exist
1422                 }
1423
1424                 $table = $this->tableName( $table );
1425                 $ignoreErrors = true;
1426                 $res = $this->query( "SELECT 1 FROM $table LIMIT 1", $fname, $ignoreErrors );
1427
1428                 return (bool)$res;
1429         }
1430
1431         public function indexUnique( $table, $index ) {
1432                 $indexInfo = $this->indexInfo( $table, $index );
1433
1434                 if ( !$indexInfo ) {
1435                         return null;
1436                 }
1437
1438                 return !$indexInfo[0]->Non_unique;
1439         }
1440
1441         /**
1442          * Helper for Database::insert().
1443          *
1444          * @param array $options
1445          * @return string
1446          */
1447         protected function makeInsertOptions( $options ) {
1448                 return implode( ' ', $options );
1449         }
1450
1451         public function insert( $table, $a, $fname = __METHOD__, $options = [] ) {
1452                 # No rows to insert, easy just return now
1453                 if ( !count( $a ) ) {
1454                         return true;
1455                 }
1456
1457                 $table = $this->tableName( $table );
1458
1459                 if ( !is_array( $options ) ) {
1460                         $options = [ $options ];
1461                 }
1462
1463                 $fh = null;
1464                 if ( isset( $options['fileHandle'] ) ) {
1465                         $fh = $options['fileHandle'];
1466                 }
1467                 $options = $this->makeInsertOptions( $options );
1468
1469                 if ( isset( $a[0] ) && is_array( $a[0] ) ) {
1470                         $multi = true;
1471                         $keys = array_keys( $a[0] );
1472                 } else {
1473                         $multi = false;
1474                         $keys = array_keys( $a );
1475                 }
1476
1477                 $sql = 'INSERT ' . $options .
1478                         " INTO $table (" . implode( ',', $keys ) . ') VALUES ';
1479
1480                 if ( $multi ) {
1481                         $first = true;
1482                         foreach ( $a as $row ) {
1483                                 if ( $first ) {
1484                                         $first = false;
1485                                 } else {
1486                                         $sql .= ',';
1487                                 }
1488                                 $sql .= '(' . $this->makeList( $row ) . ')';
1489                         }
1490                 } else {
1491                         $sql .= '(' . $this->makeList( $a ) . ')';
1492                 }
1493
1494                 if ( $fh !== null && false === fwrite( $fh, $sql ) ) {
1495                         return false;
1496                 } elseif ( $fh !== null ) {
1497                         return true;
1498                 }
1499
1500                 return (bool)$this->query( $sql, $fname );
1501         }
1502
1503         /**
1504          * Make UPDATE options array for Database::makeUpdateOptions
1505          *
1506          * @param array $options
1507          * @return array
1508          */
1509         protected function makeUpdateOptionsArray( $options ) {
1510                 if ( !is_array( $options ) ) {
1511                         $options = [ $options ];
1512                 }
1513
1514                 $opts = [];
1515
1516                 if ( in_array( 'IGNORE', $options ) ) {
1517                         $opts[] = 'IGNORE';
1518                 }
1519
1520                 return $opts;
1521         }
1522
1523         /**
1524          * Make UPDATE options for the Database::update function
1525          *
1526          * @param array $options The options passed to Database::update
1527          * @return string
1528          */
1529         protected function makeUpdateOptions( $options ) {
1530                 $opts = $this->makeUpdateOptionsArray( $options );
1531
1532                 return implode( ' ', $opts );
1533         }
1534
1535         public function update( $table, $values, $conds, $fname = __METHOD__, $options = [] ) {
1536                 $table = $this->tableName( $table );
1537                 $opts = $this->makeUpdateOptions( $options );
1538                 $sql = "UPDATE $opts $table SET " . $this->makeList( $values, self::LIST_SET );
1539
1540                 if ( $conds !== [] && $conds !== '*' ) {
1541                         $sql .= " WHERE " . $this->makeList( $conds, self::LIST_AND );
1542                 }
1543
1544                 return $this->query( $sql, $fname );
1545         }
1546
1547         public function makeList( $a, $mode = self::LIST_COMMA ) {
1548                 if ( !is_array( $a ) ) {
1549                         throw new DBUnexpectedError( $this, __METHOD__ . ' called with incorrect parameters' );
1550                 }
1551
1552                 $first = true;
1553                 $list = '';
1554
1555                 foreach ( $a as $field => $value ) {
1556                         if ( !$first ) {
1557                                 if ( $mode == self::LIST_AND ) {
1558                                         $list .= ' AND ';
1559                                 } elseif ( $mode == self::LIST_OR ) {
1560                                         $list .= ' OR ';
1561                                 } else {
1562                                         $list .= ',';
1563                                 }
1564                         } else {
1565                                 $first = false;
1566                         }
1567
1568                         if ( ( $mode == self::LIST_AND || $mode == self::LIST_OR ) && is_numeric( $field ) ) {
1569                                 $list .= "($value)";
1570                         } elseif ( $mode == self::LIST_SET && is_numeric( $field ) ) {
1571                                 $list .= "$value";
1572                         } elseif (
1573                                 ( $mode == self::LIST_AND || $mode == self::LIST_OR ) && is_array( $value )
1574                         ) {
1575                                 // Remove null from array to be handled separately if found
1576                                 $includeNull = false;
1577                                 foreach ( array_keys( $value, null, true ) as $nullKey ) {
1578                                         $includeNull = true;
1579                                         unset( $value[$nullKey] );
1580                                 }
1581                                 if ( count( $value ) == 0 && !$includeNull ) {
1582                                         throw new InvalidArgumentException(
1583                                                 __METHOD__ . ": empty input for field $field" );
1584                                 } elseif ( count( $value ) == 0 ) {
1585                                         // only check if $field is null
1586                                         $list .= "$field IS NULL";
1587                                 } else {
1588                                         // IN clause contains at least one valid element
1589                                         if ( $includeNull ) {
1590                                                 // Group subconditions to ensure correct precedence
1591                                                 $list .= '(';
1592                                         }
1593                                         if ( count( $value ) == 1 ) {
1594                                                 // Special-case single values, as IN isn't terribly efficient
1595                                                 // Don't necessarily assume the single key is 0; we don't
1596                                                 // enforce linear numeric ordering on other arrays here.
1597                                                 $value = array_values( $value )[0];
1598                                                 $list .= $field . " = " . $this->addQuotes( $value );
1599                                         } else {
1600                                                 $list .= $field . " IN (" . $this->makeList( $value ) . ") ";
1601                                         }
1602                                         // if null present in array, append IS NULL
1603                                         if ( $includeNull ) {
1604                                                 $list .= " OR $field IS NULL)";
1605                                         }
1606                                 }
1607                         } elseif ( $value === null ) {
1608                                 if ( $mode == self::LIST_AND || $mode == self::LIST_OR ) {
1609                                         $list .= "$field IS ";
1610                                 } elseif ( $mode == self::LIST_SET ) {
1611                                         $list .= "$field = ";
1612                                 }
1613                                 $list .= 'NULL';
1614                         } else {
1615                                 if (
1616                                         $mode == self::LIST_AND || $mode == self::LIST_OR || $mode == self::LIST_SET
1617                                 ) {
1618                                         $list .= "$field = ";
1619                                 }
1620                                 $list .= $mode == self::LIST_NAMES ? $value : $this->addQuotes( $value );
1621                         }
1622                 }
1623
1624                 return $list;
1625         }
1626
1627         public function makeWhereFrom2d( $data, $baseKey, $subKey ) {
1628                 $conds = [];
1629
1630                 foreach ( $data as $base => $sub ) {
1631                         if ( count( $sub ) ) {
1632                                 $conds[] = $this->makeList(
1633                                         [ $baseKey => $base, $subKey => array_keys( $sub ) ],
1634                                         self::LIST_AND );
1635                         }
1636                 }
1637
1638                 if ( $conds ) {
1639                         return $this->makeList( $conds, self::LIST_OR );
1640                 } else {
1641                         // Nothing to search for...
1642                         return false;
1643                 }
1644         }
1645
1646         public function aggregateValue( $valuedata, $valuename = 'value' ) {
1647                 return $valuename;
1648         }
1649
1650         public function bitNot( $field ) {
1651                 return "(~$field)";
1652         }
1653
1654         public function bitAnd( $fieldLeft, $fieldRight ) {
1655                 return "($fieldLeft & $fieldRight)";
1656         }
1657
1658         public function bitOr( $fieldLeft, $fieldRight ) {
1659                 return "($fieldLeft | $fieldRight)";
1660         }
1661
1662         public function buildConcat( $stringList ) {
1663                 return 'CONCAT(' . implode( ',', $stringList ) . ')';
1664         }
1665
1666         public function buildGroupConcatField(
1667                 $delim, $table, $field, $conds = '', $join_conds = []
1668         ) {
1669                 $fld = "GROUP_CONCAT($field SEPARATOR " . $this->addQuotes( $delim ) . ')';
1670
1671                 return '(' . $this->selectSQLText( $table, $fld, $conds, null, [], $join_conds ) . ')';
1672         }
1673
1674         public function buildStringCast( $field ) {
1675                 return $field;
1676         }
1677
1678         public function selectDB( $db ) {
1679                 # Stub. Shouldn't cause serious problems if it's not overridden, but
1680                 # if your database engine supports a concept similar to MySQL's
1681                 # databases you may as well.
1682                 $this->mDBname = $db;
1683
1684                 return true;
1685         }
1686
1687         public function getDBname() {
1688                 return $this->mDBname;
1689         }
1690
1691         public function getServer() {
1692                 return $this->mServer;
1693         }
1694
1695         public function tableName( $name, $format = 'quoted' ) {
1696                 # Skip the entire process when we have a string quoted on both ends.
1697                 # Note that we check the end so that we will still quote any use of
1698                 # use of `database`.table. But won't break things if someone wants
1699                 # to query a database table with a dot in the name.
1700                 if ( $this->isQuotedIdentifier( $name ) ) {
1701                         return $name;
1702                 }
1703
1704                 # Lets test for any bits of text that should never show up in a table
1705                 # name. Basically anything like JOIN or ON which are actually part of
1706                 # SQL queries, but may end up inside of the table value to combine
1707                 # sql. Such as how the API is doing.
1708                 # Note that we use a whitespace test rather than a \b test to avoid
1709                 # any remote case where a word like on may be inside of a table name
1710                 # surrounded by symbols which may be considered word breaks.
1711                 if ( preg_match( '/(^|\s)(DISTINCT|JOIN|ON|AS)(\s|$)/i', $name ) !== 0 ) {
1712                         return $name;
1713                 }
1714
1715                 # Split database and table into proper variables.
1716                 # We reverse the explode so that database.table and table both output
1717                 # the correct table.
1718                 $dbDetails = explode( '.', $name, 3 );
1719                 if ( count( $dbDetails ) == 3 ) {
1720                         list( $database, $schema, $table ) = $dbDetails;
1721                         # We don't want any prefix added in this case
1722                         $prefix = '';
1723                 } elseif ( count( $dbDetails ) == 2 ) {
1724                         list( $database, $table ) = $dbDetails;
1725                         # We don't want any prefix added in this case
1726                         $prefix = '';
1727                         # In dbs that support it, $database may actually be the schema
1728                         # but that doesn't affect any of the functionality here
1729                         $schema = '';
1730                 } else {
1731                         list( $table ) = $dbDetails;
1732                         if ( isset( $this->tableAliases[$table] ) ) {
1733                                 $database = $this->tableAliases[$table]['dbname'];
1734                                 $schema = is_string( $this->tableAliases[$table]['schema'] )
1735                                         ? $this->tableAliases[$table]['schema']
1736                                         : $this->mSchema;
1737                                 $prefix = is_string( $this->tableAliases[$table]['prefix'] )
1738                                         ? $this->tableAliases[$table]['prefix']
1739                                         : $this->mTablePrefix;
1740                         } else {
1741                                 $database = '';
1742                                 $schema = $this->mSchema; # Default schema
1743                                 $prefix = $this->mTablePrefix; # Default prefix
1744                         }
1745                 }
1746
1747                 # Quote $table and apply the prefix if not quoted.
1748                 # $tableName might be empty if this is called from Database::replaceVars()
1749                 $tableName = "{$prefix}{$table}";
1750                 if ( $format === 'quoted'
1751                         && !$this->isQuotedIdentifier( $tableName )
1752                         && $tableName !== ''
1753                 ) {
1754                         $tableName = $this->addIdentifierQuotes( $tableName );
1755                 }
1756
1757                 # Quote $schema and $database and merge them with the table name if needed
1758                 $tableName = $this->prependDatabaseOrSchema( $schema, $tableName, $format );
1759                 $tableName = $this->prependDatabaseOrSchema( $database, $tableName, $format );
1760
1761                 return $tableName;
1762         }
1763
1764         /**
1765          * @param string|null $namespace Database or schema
1766          * @param string $relation Name of table, view, sequence, etc...
1767          * @param string $format One of (raw, quoted)
1768          * @return string Relation name with quoted and merged $namespace as needed
1769          */
1770         private function prependDatabaseOrSchema( $namespace, $relation, $format ) {
1771                 if ( strlen( $namespace ) ) {
1772                         if ( $format === 'quoted' && !$this->isQuotedIdentifier( $namespace ) ) {
1773                                 $namespace = $this->addIdentifierQuotes( $namespace );
1774                         }
1775                         $relation = $namespace . '.' . $relation;
1776                 }
1777
1778                 return $relation;
1779         }
1780
1781         public function tableNames() {
1782                 $inArray = func_get_args();
1783                 $retVal = [];
1784
1785                 foreach ( $inArray as $name ) {
1786                         $retVal[$name] = $this->tableName( $name );
1787                 }
1788
1789                 return $retVal;
1790         }
1791
1792         public function tableNamesN() {
1793                 $inArray = func_get_args();
1794                 $retVal = [];
1795
1796                 foreach ( $inArray as $name ) {
1797                         $retVal[] = $this->tableName( $name );
1798                 }
1799
1800                 return $retVal;
1801         }
1802
1803         /**
1804          * Get an aliased table name
1805          * e.g. tableName AS newTableName
1806          *
1807          * @param string $name Table name, see tableName()
1808          * @param string|bool $alias Alias (optional)
1809          * @return string SQL name for aliased table. Will not alias a table to its own name
1810          */
1811         protected function tableNameWithAlias( $name, $alias = false ) {
1812                 if ( !$alias || $alias == $name ) {
1813                         return $this->tableName( $name );
1814                 } else {
1815                         return $this->tableName( $name ) . ' ' . $this->addIdentifierQuotes( $alias );
1816                 }
1817         }
1818
1819         /**
1820          * Gets an array of aliased table names
1821          *
1822          * @param array $tables [ [alias] => table ]
1823          * @return string[] See tableNameWithAlias()
1824          */
1825         protected function tableNamesWithAlias( $tables ) {
1826                 $retval = [];
1827                 foreach ( $tables as $alias => $table ) {
1828                         if ( is_numeric( $alias ) ) {
1829                                 $alias = $table;
1830                         }
1831                         $retval[] = $this->tableNameWithAlias( $table, $alias );
1832                 }
1833
1834                 return $retval;
1835         }
1836
1837         /**
1838          * Get an aliased field name
1839          * e.g. fieldName AS newFieldName
1840          *
1841          * @param string $name Field name
1842          * @param string|bool $alias Alias (optional)
1843          * @return string SQL name for aliased field. Will not alias a field to its own name
1844          */
1845         protected function fieldNameWithAlias( $name, $alias = false ) {
1846                 if ( !$alias || (string)$alias === (string)$name ) {
1847                         return $name;
1848                 } else {
1849                         return $name . ' AS ' . $this->addIdentifierQuotes( $alias ); // PostgreSQL needs AS
1850                 }
1851         }
1852
1853         /**
1854          * Gets an array of aliased field names
1855          *
1856          * @param array $fields [ [alias] => field ]
1857          * @return string[] See fieldNameWithAlias()
1858          */
1859         protected function fieldNamesWithAlias( $fields ) {
1860                 $retval = [];
1861                 foreach ( $fields as $alias => $field ) {
1862                         if ( is_numeric( $alias ) ) {
1863                                 $alias = $field;
1864                         }
1865                         $retval[] = $this->fieldNameWithAlias( $field, $alias );
1866                 }
1867
1868                 return $retval;
1869         }
1870
1871         /**
1872          * Get the aliased table name clause for a FROM clause
1873          * which might have a JOIN and/or USE INDEX or IGNORE INDEX clause
1874          *
1875          * @param array $tables ( [alias] => table )
1876          * @param array $use_index Same as for select()
1877          * @param array $ignore_index Same as for select()
1878          * @param array $join_conds Same as for select()
1879          * @return string
1880          */
1881         protected function tableNamesWithIndexClauseOrJOIN(
1882                 $tables, $use_index = [], $ignore_index = [], $join_conds = []
1883         ) {
1884                 $ret = [];
1885                 $retJOIN = [];
1886                 $use_index = (array)$use_index;
1887                 $ignore_index = (array)$ignore_index;
1888                 $join_conds = (array)$join_conds;
1889
1890                 foreach ( $tables as $alias => $table ) {
1891                         if ( !is_string( $alias ) ) {
1892                                 // No alias? Set it equal to the table name
1893                                 $alias = $table;
1894                         }
1895                         // Is there a JOIN clause for this table?
1896                         if ( isset( $join_conds[$alias] ) ) {
1897                                 list( $joinType, $conds ) = $join_conds[$alias];
1898                                 $tableClause = $joinType;
1899                                 $tableClause .= ' ' . $this->tableNameWithAlias( $table, $alias );
1900                                 if ( isset( $use_index[$alias] ) ) { // has USE INDEX?
1901                                         $use = $this->useIndexClause( implode( ',', (array)$use_index[$alias] ) );
1902                                         if ( $use != '' ) {
1903                                                 $tableClause .= ' ' . $use;
1904                                         }
1905                                 }
1906                                 if ( isset( $ignore_index[$alias] ) ) { // has IGNORE INDEX?
1907                                         $ignore = $this->ignoreIndexClause(
1908                                                 implode( ',', (array)$ignore_index[$alias] ) );
1909                                         if ( $ignore != '' ) {
1910                                                 $tableClause .= ' ' . $ignore;
1911                                         }
1912                                 }
1913                                 $on = $this->makeList( (array)$conds, self::LIST_AND );
1914                                 if ( $on != '' ) {
1915                                         $tableClause .= ' ON (' . $on . ')';
1916                                 }
1917
1918                                 $retJOIN[] = $tableClause;
1919                         } elseif ( isset( $use_index[$alias] ) ) {
1920                                 // Is there an INDEX clause for this table?
1921                                 $tableClause = $this->tableNameWithAlias( $table, $alias );
1922                                 $tableClause .= ' ' . $this->useIndexClause(
1923                                                 implode( ',', (array)$use_index[$alias] )
1924                                         );
1925
1926                                 $ret[] = $tableClause;
1927                         } elseif ( isset( $ignore_index[$alias] ) ) {
1928                                 // Is there an INDEX clause for this table?
1929                                 $tableClause = $this->tableNameWithAlias( $table, $alias );
1930                                 $tableClause .= ' ' . $this->ignoreIndexClause(
1931                                                 implode( ',', (array)$ignore_index[$alias] )
1932                                         );
1933
1934                                 $ret[] = $tableClause;
1935                         } else {
1936                                 $tableClause = $this->tableNameWithAlias( $table, $alias );
1937
1938                                 $ret[] = $tableClause;
1939                         }
1940                 }
1941
1942                 // We can't separate explicit JOIN clauses with ',', use ' ' for those
1943                 $implicitJoins = !empty( $ret ) ? implode( ',', $ret ) : "";
1944                 $explicitJoins = !empty( $retJOIN ) ? implode( ' ', $retJOIN ) : "";
1945
1946                 // Compile our final table clause
1947                 return implode( ' ', [ $implicitJoins, $explicitJoins ] );
1948         }
1949
1950         /**
1951          * Get the name of an index in a given table.
1952          *
1953          * @param string $index
1954          * @return string
1955          */
1956         protected function indexName( $index ) {
1957                 return $index;
1958         }
1959
1960         public function addQuotes( $s ) {
1961                 if ( $s instanceof Blob ) {
1962                         $s = $s->fetch();
1963                 }
1964                 if ( $s === null ) {
1965                         return 'NULL';
1966                 } elseif ( is_bool( $s ) ) {
1967                         return (int)$s;
1968                 } else {
1969                         # This will also quote numeric values. This should be harmless,
1970                         # and protects against weird problems that occur when they really
1971                         # _are_ strings such as article titles and string->number->string
1972                         # conversion is not 1:1.
1973                         return "'" . $this->strencode( $s ) . "'";
1974                 }
1975         }
1976
1977         /**
1978          * Quotes an identifier using `backticks` or "double quotes" depending on the database type.
1979          * MySQL uses `backticks` while basically everything else uses double quotes.
1980          * Since MySQL is the odd one out here the double quotes are our generic
1981          * and we implement backticks in DatabaseMysql.
1982          *
1983          * @param string $s
1984          * @return string
1985          */
1986         public function addIdentifierQuotes( $s ) {
1987                 return '"' . str_replace( '"', '""', $s ) . '"';
1988         }
1989
1990         /**
1991          * Returns if the given identifier looks quoted or not according to
1992          * the database convention for quoting identifiers .
1993          *
1994          * @note Do not use this to determine if untrusted input is safe.
1995          *   A malicious user can trick this function.
1996          * @param string $name
1997          * @return bool
1998          */
1999         public function isQuotedIdentifier( $name ) {
2000                 return $name[0] == '"' && substr( $name, -1, 1 ) == '"';
2001         }
2002
2003         /**
2004          * @param string $s
2005          * @return string
2006          */
2007         protected function escapeLikeInternal( $s ) {
2008                 return addcslashes( $s, '\%_' );
2009         }
2010
2011         public function buildLike() {
2012                 $params = func_get_args();
2013
2014                 if ( count( $params ) > 0 && is_array( $params[0] ) ) {
2015                         $params = $params[0];
2016                 }
2017
2018                 $s = '';
2019
2020                 foreach ( $params as $value ) {
2021                         if ( $value instanceof LikeMatch ) {
2022                                 $s .= $value->toString();
2023                         } else {
2024                                 $s .= $this->escapeLikeInternal( $value );
2025                         }
2026                 }
2027
2028                 return " LIKE {$this->addQuotes( $s )} ";
2029         }
2030
2031         public function anyChar() {
2032                 return new LikeMatch( '_' );
2033         }
2034
2035         public function anyString() {
2036                 return new LikeMatch( '%' );
2037         }
2038
2039         public function nextSequenceValue( $seqName ) {
2040                 return null;
2041         }
2042
2043         /**
2044          * USE INDEX clause. Unlikely to be useful for anything but MySQL. This
2045          * is only needed because a) MySQL must be as efficient as possible due to
2046          * its use on Wikipedia, and b) MySQL 4.0 is kind of dumb sometimes about
2047          * which index to pick. Anyway, other databases might have different
2048          * indexes on a given table. So don't bother overriding this unless you're
2049          * MySQL.
2050          * @param string $index
2051          * @return string
2052          */
2053         public function useIndexClause( $index ) {
2054                 return '';
2055         }
2056
2057         /**
2058          * IGNORE INDEX clause. Unlikely to be useful for anything but MySQL. This
2059          * is only needed because a) MySQL must be as efficient as possible due to
2060          * its use on Wikipedia, and b) MySQL 4.0 is kind of dumb sometimes about
2061          * which index to pick. Anyway, other databases might have different
2062          * indexes on a given table. So don't bother overriding this unless you're
2063          * MySQL.
2064          * @param string $index
2065          * @return string
2066          */
2067         public function ignoreIndexClause( $index ) {
2068                 return '';
2069         }
2070
2071         public function replace( $table, $uniqueIndexes, $rows, $fname = __METHOD__ ) {
2072                 $quotedTable = $this->tableName( $table );
2073
2074                 if ( count( $rows ) == 0 ) {
2075                         return;
2076                 }
2077
2078                 # Single row case
2079                 if ( !is_array( reset( $rows ) ) ) {
2080                         $rows = [ $rows ];
2081                 }
2082
2083                 // @FXIME: this is not atomic, but a trx would break affectedRows()
2084                 foreach ( $rows as $row ) {
2085                         # Delete rows which collide
2086                         if ( $uniqueIndexes ) {
2087                                 $sql = "DELETE FROM $quotedTable WHERE ";
2088                                 $first = true;
2089                                 foreach ( $uniqueIndexes as $index ) {
2090                                         if ( $first ) {
2091                                                 $first = false;
2092                                                 $sql .= '( ';
2093                                         } else {
2094                                                 $sql .= ' ) OR ( ';
2095                                         }
2096                                         if ( is_array( $index ) ) {
2097                                                 $first2 = true;
2098                                                 foreach ( $index as $col ) {
2099                                                         if ( $first2 ) {
2100                                                                 $first2 = false;
2101                                                         } else {
2102                                                                 $sql .= ' AND ';
2103                                                         }
2104                                                         $sql .= $col . '=' . $this->addQuotes( $row[$col] );
2105                                                 }
2106                                         } else {
2107                                                 $sql .= $index . '=' . $this->addQuotes( $row[$index] );
2108                                         }
2109                                 }
2110                                 $sql .= ' )';
2111                                 $this->query( $sql, $fname );
2112                         }
2113
2114                         # Now insert the row
2115                         $this->insert( $table, $row, $fname );
2116                 }
2117         }
2118
2119         /**
2120          * REPLACE query wrapper for MySQL and SQLite, which have a native REPLACE
2121          * statement.
2122          *
2123          * @param string $table Table name
2124          * @param array|string $rows Row(s) to insert
2125          * @param string $fname Caller function name
2126          *
2127          * @return ResultWrapper
2128          */
2129         protected function nativeReplace( $table, $rows, $fname ) {
2130                 $table = $this->tableName( $table );
2131
2132                 # Single row case
2133                 if ( !is_array( reset( $rows ) ) ) {
2134                         $rows = [ $rows ];
2135                 }
2136
2137                 $sql = "REPLACE INTO $table (" . implode( ',', array_keys( $rows[0] ) ) . ') VALUES ';
2138                 $first = true;
2139
2140                 foreach ( $rows as $row ) {
2141                         if ( $first ) {
2142                                 $first = false;
2143                         } else {
2144                                 $sql .= ',';
2145                         }
2146
2147                         $sql .= '(' . $this->makeList( $row ) . ')';
2148                 }
2149
2150                 return $this->query( $sql, $fname );
2151         }
2152
2153         public function upsert( $table, array $rows, array $uniqueIndexes, array $set,
2154                 $fname = __METHOD__
2155         ) {
2156                 if ( !count( $rows ) ) {
2157                         return true; // nothing to do
2158                 }
2159
2160                 if ( !is_array( reset( $rows ) ) ) {
2161                         $rows = [ $rows ];
2162                 }
2163
2164                 if ( count( $uniqueIndexes ) ) {
2165                         $clauses = []; // list WHERE clauses that each identify a single row
2166                         foreach ( $rows as $row ) {
2167                                 foreach ( $uniqueIndexes as $index ) {
2168                                         $index = is_array( $index ) ? $index : [ $index ]; // columns
2169                                         $rowKey = []; // unique key to this row
2170                                         foreach ( $index as $column ) {
2171                                                 $rowKey[$column] = $row[$column];
2172                                         }
2173                                         $clauses[] = $this->makeList( $rowKey, self::LIST_AND );
2174                                 }
2175                         }
2176                         $where = [ $this->makeList( $clauses, self::LIST_OR ) ];
2177                 } else {
2178                         $where = false;
2179                 }
2180
2181                 $useTrx = !$this->mTrxLevel;
2182                 if ( $useTrx ) {
2183                         $this->begin( $fname, self::TRANSACTION_INTERNAL );
2184                 }
2185                 try {
2186                         # Update any existing conflicting row(s)
2187                         if ( $where !== false ) {
2188                                 $ok = $this->update( $table, $set, $where, $fname );
2189                         } else {
2190                                 $ok = true;
2191                         }
2192                         # Now insert any non-conflicting row(s)
2193                         $ok = $this->insert( $table, $rows, $fname, [ 'IGNORE' ] ) && $ok;
2194                 } catch ( Exception $e ) {
2195                         if ( $useTrx ) {
2196                                 $this->rollback( $fname, self::FLUSHING_INTERNAL );
2197                         }
2198                         throw $e;
2199                 }
2200                 if ( $useTrx ) {
2201                         $this->commit( $fname, self::FLUSHING_INTERNAL );
2202                 }
2203
2204                 return $ok;
2205         }
2206
2207         public function deleteJoin( $delTable, $joinTable, $delVar, $joinVar, $conds,
2208                 $fname = __METHOD__
2209         ) {
2210                 if ( !$conds ) {
2211                         throw new DBUnexpectedError( $this, __METHOD__ . ' called with empty $conds' );
2212                 }
2213
2214                 $delTable = $this->tableName( $delTable );
2215                 $joinTable = $this->tableName( $joinTable );
2216                 $sql = "DELETE FROM $delTable WHERE $delVar IN (SELECT $joinVar FROM $joinTable ";
2217                 if ( $conds != '*' ) {
2218                         $sql .= 'WHERE ' . $this->makeList( $conds, self::LIST_AND );
2219                 }
2220                 $sql .= ')';
2221
2222                 $this->query( $sql, $fname );
2223         }
2224
2225         public function textFieldSize( $table, $field ) {
2226                 $table = $this->tableName( $table );
2227                 $sql = "SHOW COLUMNS FROM $table LIKE \"$field\";";
2228                 $res = $this->query( $sql, __METHOD__ );
2229                 $row = $this->fetchObject( $res );
2230
2231                 $m = [];
2232
2233                 if ( preg_match( '/\((.*)\)/', $row->Type, $m ) ) {
2234                         $size = $m[1];
2235                 } else {
2236                         $size = -1;
2237                 }
2238
2239                 return $size;
2240         }
2241
2242         public function delete( $table, $conds, $fname = __METHOD__ ) {
2243                 if ( !$conds ) {
2244                         throw new DBUnexpectedError( $this, __METHOD__ . ' called with no conditions' );
2245                 }
2246
2247                 $table = $this->tableName( $table );
2248                 $sql = "DELETE FROM $table";
2249
2250                 if ( $conds != '*' ) {
2251                         if ( is_array( $conds ) ) {
2252                                 $conds = $this->makeList( $conds, self::LIST_AND );
2253                         }
2254                         $sql .= ' WHERE ' . $conds;
2255                 }
2256
2257                 return $this->query( $sql, $fname );
2258         }
2259
2260         public function insertSelect(
2261                 $destTable, $srcTable, $varMap, $conds,
2262                 $fname = __METHOD__, $insertOptions = [], $selectOptions = []
2263         ) {
2264                 if ( $this->cliMode ) {
2265                         // For massive migrations with downtime, we don't want to select everything
2266                         // into memory and OOM, so do all this native on the server side if possible.
2267                         return $this->nativeInsertSelect(
2268                                 $destTable,
2269                                 $srcTable,
2270                                 $varMap,
2271                                 $conds,
2272                                 $fname,
2273                                 $insertOptions,
2274                                 $selectOptions
2275                         );
2276                 }
2277
2278                 // For web requests, do a locking SELECT and then INSERT. This puts the SELECT burden
2279                 // on only the master (without needing row-based-replication). It also makes it easy to
2280                 // know how big the INSERT is going to be.
2281                 $fields = [];
2282                 foreach ( $varMap as $dstColumn => $sourceColumnOrSql ) {
2283                         $fields[] = $this->fieldNameWithAlias( $sourceColumnOrSql, $dstColumn );
2284                 }
2285                 $selectOptions[] = 'FOR UPDATE';
2286                 $res = $this->select( $srcTable, implode( ',', $fields ), $conds, $fname, $selectOptions );
2287                 if ( !$res ) {
2288                         return false;
2289                 }
2290
2291                 $rows = [];
2292                 foreach ( $res as $row ) {
2293                         $rows[] = (array)$row;
2294                 }
2295
2296                 return $this->insert( $destTable, $rows, $fname, $insertOptions );
2297         }
2298
2299         protected function nativeInsertSelect( $destTable, $srcTable, $varMap, $conds,
2300                 $fname = __METHOD__,
2301                 $insertOptions = [], $selectOptions = []
2302         ) {
2303                 $destTable = $this->tableName( $destTable );
2304
2305                 if ( !is_array( $insertOptions ) ) {
2306                         $insertOptions = [ $insertOptions ];
2307                 }
2308
2309                 $insertOptions = $this->makeInsertOptions( $insertOptions );
2310
2311                 if ( !is_array( $selectOptions ) ) {
2312                         $selectOptions = [ $selectOptions ];
2313                 }
2314
2315                 list( $startOpts, $useIndex, $tailOpts, $ignoreIndex ) = $this->makeSelectOptions(
2316                         $selectOptions );
2317
2318                 if ( is_array( $srcTable ) ) {
2319                         $srcTable = implode( ',', array_map( [ $this, 'tableName' ], $srcTable ) );
2320                 } else {
2321                         $srcTable = $this->tableName( $srcTable );
2322                 }
2323
2324                 $sql = "INSERT $insertOptions" .
2325                         " INTO $destTable (" . implode( ',', array_keys( $varMap ) ) . ')' .
2326                         " SELECT $startOpts " . implode( ',', $varMap ) .
2327                         " FROM $srcTable $useIndex $ignoreIndex ";
2328
2329                 if ( $conds != '*' ) {
2330                         if ( is_array( $conds ) ) {
2331                                 $conds = $this->makeList( $conds, self::LIST_AND );
2332                         }
2333                         $sql .= " WHERE $conds";
2334                 }
2335
2336                 $sql .= " $tailOpts";
2337
2338                 return $this->query( $sql, $fname );
2339         }
2340
2341         /**
2342          * Construct a LIMIT query with optional offset. This is used for query
2343          * pages. The SQL should be adjusted so that only the first $limit rows
2344          * are returned. If $offset is provided as well, then the first $offset
2345          * rows should be discarded, and the next $limit rows should be returned.
2346          * If the result of the query is not ordered, then the rows to be returned
2347          * are theoretically arbitrary.
2348          *
2349          * $sql is expected to be a SELECT, if that makes a difference.
2350          *
2351          * The version provided by default works in MySQL and SQLite. It will very
2352          * likely need to be overridden for most other DBMSes.
2353          *
2354          * @param string $sql SQL query we will append the limit too
2355          * @param int $limit The SQL limit
2356          * @param int|bool $offset The SQL offset (default false)
2357          * @throws DBUnexpectedError
2358          * @return string
2359          */
2360         public function limitResult( $sql, $limit, $offset = false ) {
2361                 if ( !is_numeric( $limit ) ) {
2362                         throw new DBUnexpectedError( $this,
2363                                 "Invalid non-numeric limit passed to limitResult()\n" );
2364                 }
2365
2366                 return "$sql LIMIT "
2367                 . ( ( is_numeric( $offset ) && $offset != 0 ) ? "{$offset}," : "" )
2368                 . "{$limit} ";
2369         }
2370
2371         public function unionSupportsOrderAndLimit() {
2372                 return true; // True for almost every DB supported
2373         }
2374
2375         public function unionQueries( $sqls, $all ) {
2376                 $glue = $all ? ') UNION ALL (' : ') UNION (';
2377
2378                 return '(' . implode( $glue, $sqls ) . ')';
2379         }
2380
2381         public function conditional( $cond, $trueVal, $falseVal ) {
2382                 if ( is_array( $cond ) ) {
2383                         $cond = $this->makeList( $cond, self::LIST_AND );
2384                 }
2385
2386                 return " (CASE WHEN $cond THEN $trueVal ELSE $falseVal END) ";
2387         }
2388
2389         public function strreplace( $orig, $old, $new ) {
2390                 return "REPLACE({$orig}, {$old}, {$new})";
2391         }
2392
2393         public function getServerUptime() {
2394                 return 0;
2395         }
2396
2397         public function wasDeadlock() {
2398                 return false;
2399         }
2400
2401         public function wasLockTimeout() {
2402                 return false;
2403         }
2404
2405         public function wasErrorReissuable() {
2406                 return false;
2407         }
2408
2409         public function wasReadOnlyError() {
2410                 return false;
2411         }
2412
2413         /**
2414          * Do not use this method outside of Database/DBError classes
2415          *
2416          * @param integer|string $errno
2417          * @return bool Whether the given query error was a connection drop
2418          */
2419         public function wasConnectionError( $errno ) {
2420                 return false;
2421         }
2422
2423         public function deadlockLoop() {
2424                 $args = func_get_args();
2425                 $function = array_shift( $args );
2426                 $tries = self::DEADLOCK_TRIES;
2427
2428                 $this->begin( __METHOD__ );
2429
2430                 $retVal = null;
2431                 /** @var Exception $e */
2432                 $e = null;
2433                 do {
2434                         try {
2435                                 $retVal = call_user_func_array( $function, $args );
2436                                 break;
2437                         } catch ( DBQueryError $e ) {
2438                                 if ( $this->wasDeadlock() ) {
2439                                         // Retry after a randomized delay
2440                                         usleep( mt_rand( self::DEADLOCK_DELAY_MIN, self::DEADLOCK_DELAY_MAX ) );
2441                                 } else {
2442                                         // Throw the error back up
2443                                         throw $e;
2444                                 }
2445                         }
2446                 } while ( --$tries > 0 );
2447
2448                 if ( $tries <= 0 ) {
2449                         // Too many deadlocks; give up
2450                         $this->rollback( __METHOD__ );
2451                         throw $e;
2452                 } else {
2453                         $this->commit( __METHOD__ );
2454
2455                         return $retVal;
2456                 }
2457         }
2458
2459         public function masterPosWait( DBMasterPos $pos, $timeout ) {
2460                 # Real waits are implemented in the subclass.
2461                 return 0;
2462         }
2463
2464         public function getReplicaPos() {
2465                 # Stub
2466                 return false;
2467         }
2468
2469         public function getMasterPos() {
2470                 # Stub
2471                 return false;
2472         }
2473
2474         public function serverIsReadOnly() {
2475                 return false;
2476         }
2477
2478         final public function onTransactionResolution( callable $callback, $fname = __METHOD__ ) {
2479                 if ( !$this->mTrxLevel ) {
2480                         throw new DBUnexpectedError( $this, "No transaction is active." );
2481                 }
2482                 $this->mTrxEndCallbacks[] = [ $callback, $fname ];
2483         }
2484
2485         final public function onTransactionIdle( callable $callback, $fname = __METHOD__ ) {
2486                 $this->mTrxIdleCallbacks[] = [ $callback, $fname ];
2487                 if ( !$this->mTrxLevel ) {
2488                         $this->runOnTransactionIdleCallbacks( self::TRIGGER_IDLE );
2489                 }
2490         }
2491
2492         final public function onTransactionPreCommitOrIdle( callable $callback, $fname = __METHOD__ ) {
2493                 if ( $this->mTrxLevel ) {
2494                         $this->mTrxPreCommitCallbacks[] = [ $callback, $fname ];
2495                 } else {
2496                         // If no transaction is active, then make one for this callback
2497                         $this->startAtomic( __METHOD__ );
2498                         try {
2499                                 call_user_func( $callback );
2500                                 $this->endAtomic( __METHOD__ );
2501                         } catch ( Exception $e ) {
2502                                 $this->rollback( __METHOD__, self::FLUSHING_INTERNAL );
2503                                 throw $e;
2504                         }
2505                 }
2506         }
2507
2508         final public function setTransactionListener( $name, callable $callback = null ) {
2509                 if ( $callback ) {
2510                         $this->mTrxRecurringCallbacks[$name] = $callback;
2511                 } else {
2512                         unset( $this->mTrxRecurringCallbacks[$name] );
2513                 }
2514         }
2515
2516         /**
2517          * Whether to disable running of post-COMMIT/ROLLBACK callbacks
2518          *
2519          * This method should not be used outside of Database/LoadBalancer
2520          *
2521          * @param bool $suppress
2522          * @since 1.28
2523          */
2524         final public function setTrxEndCallbackSuppression( $suppress ) {
2525                 $this->mTrxEndCallbacksSuppressed = $suppress;
2526         }
2527
2528         /**
2529          * Actually run and consume any "on transaction idle/resolution" callbacks.
2530          *
2531          * This method should not be used outside of Database/LoadBalancer
2532          *
2533          * @param integer $trigger IDatabase::TRIGGER_* constant
2534          * @since 1.20
2535          * @throws Exception
2536          */
2537         public function runOnTransactionIdleCallbacks( $trigger ) {
2538                 if ( $this->mTrxEndCallbacksSuppressed ) {
2539                         return;
2540                 }
2541
2542                 $autoTrx = $this->getFlag( self::DBO_TRX ); // automatic begin() enabled?
2543                 /** @var Exception $e */
2544                 $e = null; // first exception
2545                 do { // callbacks may add callbacks :)
2546                         $callbacks = array_merge(
2547                                 $this->mTrxIdleCallbacks,
2548                                 $this->mTrxEndCallbacks // include "transaction resolution" callbacks
2549                         );
2550                         $this->mTrxIdleCallbacks = []; // consumed (and recursion guard)
2551                         $this->mTrxEndCallbacks = []; // consumed (recursion guard)
2552                         foreach ( $callbacks as $callback ) {
2553                                 try {
2554                                         list( $phpCallback ) = $callback;
2555                                         $this->clearFlag( self::DBO_TRX ); // make each query its own transaction
2556                                         call_user_func_array( $phpCallback, [ $trigger ] );
2557                                         if ( $autoTrx ) {
2558                                                 $this->setFlag( self::DBO_TRX ); // restore automatic begin()
2559                                         } else {
2560                                                 $this->clearFlag( self::DBO_TRX ); // restore auto-commit
2561                                         }
2562                                 } catch ( Exception $ex ) {
2563                                         call_user_func( $this->errorLogger, $ex );
2564                                         $e = $e ?: $ex;
2565                                         // Some callbacks may use startAtomic/endAtomic, so make sure
2566                                         // their transactions are ended so other callbacks don't fail
2567                                         if ( $this->trxLevel() ) {
2568                                                 $this->rollback( __METHOD__, self::FLUSHING_INTERNAL );
2569                                         }
2570                                 }
2571                         }
2572                 } while ( count( $this->mTrxIdleCallbacks ) );
2573
2574                 if ( $e instanceof Exception ) {
2575                         throw $e; // re-throw any first exception
2576                 }
2577         }
2578
2579         /**
2580          * Actually run and consume any "on transaction pre-commit" callbacks.
2581          *
2582          * This method should not be used outside of Database/LoadBalancer
2583          *
2584          * @since 1.22
2585          * @throws Exception
2586          */
2587         public function runOnTransactionPreCommitCallbacks() {
2588                 $e = null; // first exception
2589                 do { // callbacks may add callbacks :)
2590                         $callbacks = $this->mTrxPreCommitCallbacks;
2591                         $this->mTrxPreCommitCallbacks = []; // consumed (and recursion guard)
2592                         foreach ( $callbacks as $callback ) {
2593                                 try {
2594                                         list( $phpCallback ) = $callback;
2595                                         call_user_func( $phpCallback );
2596                                 } catch ( Exception $ex ) {
2597                                         call_user_func( $this->errorLogger, $ex );
2598                                         $e = $e ?: $ex;
2599                                 }
2600                         }
2601                 } while ( count( $this->mTrxPreCommitCallbacks ) );
2602
2603                 if ( $e instanceof Exception ) {
2604                         throw $e; // re-throw any first exception
2605                 }
2606         }
2607
2608         /**
2609          * Actually run any "transaction listener" callbacks.
2610          *
2611          * This method should not be used outside of Database/LoadBalancer
2612          *
2613          * @param integer $trigger IDatabase::TRIGGER_* constant
2614          * @throws Exception
2615          * @since 1.20
2616          */
2617         public function runTransactionListenerCallbacks( $trigger ) {
2618                 if ( $this->mTrxEndCallbacksSuppressed ) {
2619                         return;
2620                 }
2621
2622                 /** @var Exception $e */
2623                 $e = null; // first exception
2624
2625                 foreach ( $this->mTrxRecurringCallbacks as $phpCallback ) {
2626                         try {
2627                                 $phpCallback( $trigger, $this );
2628                         } catch ( Exception $ex ) {
2629                                 call_user_func( $this->errorLogger, $ex );
2630                                 $e = $e ?: $ex;
2631                         }
2632                 }
2633
2634                 if ( $e instanceof Exception ) {
2635                         throw $e; // re-throw any first exception
2636                 }
2637         }
2638
2639         final public function startAtomic( $fname = __METHOD__ ) {
2640                 if ( !$this->mTrxLevel ) {
2641                         $this->begin( $fname, self::TRANSACTION_INTERNAL );
2642                         // If DBO_TRX is set, a series of startAtomic/endAtomic pairs will result
2643                         // in all changes being in one transaction to keep requests transactional.
2644                         if ( !$this->getFlag( self::DBO_TRX ) ) {
2645                                 $this->mTrxAutomaticAtomic = true;
2646                         }
2647                 }
2648
2649                 $this->mTrxAtomicLevels[] = $fname;
2650         }
2651
2652         final public function endAtomic( $fname = __METHOD__ ) {
2653                 if ( !$this->mTrxLevel ) {
2654                         throw new DBUnexpectedError( $this, "No atomic transaction is open (got $fname)." );
2655                 }
2656                 if ( !$this->mTrxAtomicLevels ||
2657                         array_pop( $this->mTrxAtomicLevels ) !== $fname
2658                 ) {
2659                         throw new DBUnexpectedError( $this, "Invalid atomic section ended (got $fname)." );
2660                 }
2661
2662                 if ( !$this->mTrxAtomicLevels && $this->mTrxAutomaticAtomic ) {
2663                         $this->commit( $fname, self::FLUSHING_INTERNAL );
2664                 }
2665         }
2666
2667         final public function doAtomicSection( $fname, callable $callback ) {
2668                 $this->startAtomic( $fname );
2669                 try {
2670                         $res = call_user_func_array( $callback, [ $this, $fname ] );
2671                 } catch ( Exception $e ) {
2672                         $this->rollback( $fname, self::FLUSHING_INTERNAL );
2673                         throw $e;
2674                 }
2675                 $this->endAtomic( $fname );
2676
2677                 return $res;
2678         }
2679
2680         final public function begin( $fname = __METHOD__, $mode = self::TRANSACTION_EXPLICIT ) {
2681                 // Protect against mismatched atomic section, transaction nesting, and snapshot loss
2682                 if ( $this->mTrxLevel ) {
2683                         if ( $this->mTrxAtomicLevels ) {
2684                                 $levels = implode( ', ', $this->mTrxAtomicLevels );
2685                                 $msg = "$fname: Got explicit BEGIN while atomic section(s) $levels are open.";
2686                                 throw new DBUnexpectedError( $this, $msg );
2687                         } elseif ( !$this->mTrxAutomatic ) {
2688                                 $msg = "$fname: Explicit transaction already active (from {$this->mTrxFname}).";
2689                                 throw new DBUnexpectedError( $this, $msg );
2690                         } else {
2691                                 // @TODO: make this an exception at some point
2692                                 $msg = "$fname: Implicit transaction already active (from {$this->mTrxFname}).";
2693                                 $this->queryLogger->error( $msg );
2694                                 return; // join the main transaction set
2695                         }
2696                 } elseif ( $this->getFlag( self::DBO_TRX ) && $mode !== self::TRANSACTION_INTERNAL ) {
2697                         // @TODO: make this an exception at some point
2698                         $msg = "$fname: Implicit transaction expected (DBO_TRX set).";
2699                         $this->queryLogger->error( $msg );
2700                         return; // let any writes be in the main transaction
2701                 }
2702
2703                 // Avoid fatals if close() was called
2704                 $this->assertOpen();
2705
2706                 $this->doBegin( $fname );
2707                 $this->mTrxTimestamp = microtime( true );
2708                 $this->mTrxFname = $fname;
2709                 $this->mTrxDoneWrites = false;
2710                 $this->mTrxAutomaticAtomic = false;
2711                 $this->mTrxAtomicLevels = [];
2712                 $this->mTrxShortId = sprintf( '%06x', mt_rand( 0, 0xffffff ) );
2713                 $this->mTrxWriteDuration = 0.0;
2714                 $this->mTrxWriteQueryCount = 0;
2715                 $this->mTrxWriteAdjDuration = 0.0;
2716                 $this->mTrxWriteAdjQueryCount = 0;
2717                 $this->mTrxWriteCallers = [];
2718                 // First SELECT after BEGIN will establish the snapshot in REPEATABLE-READ.
2719                 // Get an estimate of the replica DB lag before then, treating estimate staleness
2720                 // as lag itself just to be safe
2721                 $status = $this->getApproximateLagStatus();
2722                 $this->mTrxReplicaLag = $status['lag'] + ( microtime( true ) - $status['since'] );
2723                 // T147697: make explicitTrxActive() return true until begin() finishes. This way, no
2724                 // caller will think its OK to muck around with the transaction just because startAtomic()
2725                 // has not yet completed (e.g. setting mTrxAtomicLevels).
2726                 $this->mTrxAutomatic = ( $mode === self::TRANSACTION_INTERNAL );
2727         }
2728
2729         /**
2730          * Issues the BEGIN command to the database server.
2731          *
2732          * @see Database::begin()
2733          * @param string $fname
2734          */
2735         protected function doBegin( $fname ) {
2736                 $this->query( 'BEGIN', $fname );
2737                 $this->mTrxLevel = 1;
2738         }
2739
2740         final public function commit( $fname = __METHOD__, $flush = '' ) {
2741                 if ( $this->mTrxLevel && $this->mTrxAtomicLevels ) {
2742                         // There are still atomic sections open. This cannot be ignored
2743                         $levels = implode( ', ', $this->mTrxAtomicLevels );
2744                         throw new DBUnexpectedError(
2745                                 $this,
2746                                 "$fname: Got COMMIT while atomic sections $levels are still open."
2747                         );
2748                 }
2749
2750                 if ( $flush === self::FLUSHING_INTERNAL || $flush === self::FLUSHING_ALL_PEERS ) {
2751                         if ( !$this->mTrxLevel ) {
2752                                 return; // nothing to do
2753                         } elseif ( !$this->mTrxAutomatic ) {
2754                                 throw new DBUnexpectedError(
2755                                         $this,
2756                                         "$fname: Flushing an explicit transaction, getting out of sync."
2757                                 );
2758                         }
2759                 } else {
2760                         if ( !$this->mTrxLevel ) {
2761                                 $this->queryLogger->error(
2762                                         "$fname: No transaction to commit, something got out of sync." );
2763                                 return; // nothing to do
2764                         } elseif ( $this->mTrxAutomatic ) {
2765                                 // @TODO: make this an exception at some point
2766                                 $msg = "$fname: Explicit commit of implicit transaction.";
2767                                 $this->queryLogger->error( $msg );
2768                                 return; // wait for the main transaction set commit round
2769                         }
2770                 }
2771
2772                 // Avoid fatals if close() was called
2773                 $this->assertOpen();
2774
2775                 $this->runOnTransactionPreCommitCallbacks();
2776                 $writeTime = $this->pendingWriteQueryDuration( self::ESTIMATE_DB_APPLY );
2777                 $this->doCommit( $fname );
2778                 if ( $this->mTrxDoneWrites ) {
2779                         $this->mLastWriteTime = microtime( true );
2780                         $this->trxProfiler->transactionWritingOut(
2781                                 $this->mServer, $this->mDBname, $this->mTrxShortId, $writeTime );
2782                 }
2783
2784                 $this->runOnTransactionIdleCallbacks( self::TRIGGER_COMMIT );
2785                 $this->runTransactionListenerCallbacks( self::TRIGGER_COMMIT );
2786         }
2787
2788         /**
2789          * Issues the COMMIT command to the database server.
2790          *
2791          * @see Database::commit()
2792          * @param string $fname
2793          */
2794         protected function doCommit( $fname ) {
2795                 if ( $this->mTrxLevel ) {
2796                         $this->query( 'COMMIT', $fname );
2797                         $this->mTrxLevel = 0;
2798                 }
2799         }
2800
2801         final public function rollback( $fname = __METHOD__, $flush = '' ) {
2802                 if ( $flush === self::FLUSHING_INTERNAL || $flush === self::FLUSHING_ALL_PEERS ) {
2803                         if ( !$this->mTrxLevel ) {
2804                                 return; // nothing to do
2805                         }
2806                 } else {
2807                         if ( !$this->mTrxLevel ) {
2808                                 $this->queryLogger->error(
2809                                         "$fname: No transaction to rollback, something got out of sync." );
2810                                 return; // nothing to do
2811                         } elseif ( $this->getFlag( self::DBO_TRX ) ) {
2812                                 throw new DBUnexpectedError(
2813                                         $this,
2814                                         "$fname: Expected mass rollback of all peer databases (DBO_TRX set)."
2815                                 );
2816                         }
2817                 }
2818
2819                 // Avoid fatals if close() was called
2820                 $this->assertOpen();
2821
2822                 $this->doRollback( $fname );
2823                 $this->mTrxAtomicLevels = [];
2824                 if ( $this->mTrxDoneWrites ) {
2825                         $this->trxProfiler->transactionWritingOut(
2826                                 $this->mServer, $this->mDBname, $this->mTrxShortId );
2827                 }
2828
2829                 $this->mTrxIdleCallbacks = []; // clear
2830                 $this->mTrxPreCommitCallbacks = []; // clear
2831                 $this->runOnTransactionIdleCallbacks( self::TRIGGER_ROLLBACK );
2832                 $this->runTransactionListenerCallbacks( self::TRIGGER_ROLLBACK );
2833         }
2834
2835         /**
2836          * Issues the ROLLBACK command to the database server.
2837          *
2838          * @see Database::rollback()
2839          * @param string $fname
2840          */
2841         protected function doRollback( $fname ) {
2842                 if ( $this->mTrxLevel ) {
2843                         # Disconnects cause rollback anyway, so ignore those errors
2844                         $ignoreErrors = true;
2845                         $this->query( 'ROLLBACK', $fname, $ignoreErrors );
2846                         $this->mTrxLevel = 0;
2847                 }
2848         }
2849
2850         public function flushSnapshot( $fname = __METHOD__ ) {
2851                 if ( $this->writesOrCallbacksPending() || $this->explicitTrxActive() ) {
2852                         // This only flushes transactions to clear snapshots, not to write data
2853                         $fnames = implode( ', ', $this->pendingWriteAndCallbackCallers() );
2854                         throw new DBUnexpectedError(
2855                                 $this,
2856                                 "$fname: Cannot flush snapshot because writes are pending ($fnames)."
2857                         );
2858                 }
2859
2860                 $this->commit( $fname, self::FLUSHING_INTERNAL );
2861         }
2862
2863         public function explicitTrxActive() {
2864                 return $this->mTrxLevel && ( $this->mTrxAtomicLevels || !$this->mTrxAutomatic );
2865         }
2866
2867         public function duplicateTableStructure(
2868                 $oldName, $newName, $temporary = false, $fname = __METHOD__
2869         ) {
2870                 throw new RuntimeException( __METHOD__ . ' is not implemented in descendant class' );
2871         }
2872
2873         public function listTables( $prefix = null, $fname = __METHOD__ ) {
2874                 throw new RuntimeException( __METHOD__ . ' is not implemented in descendant class' );
2875         }
2876
2877         public function listViews( $prefix = null, $fname = __METHOD__ ) {
2878                 throw new RuntimeException( __METHOD__ . ' is not implemented in descendant class' );
2879         }
2880
2881         public function timestamp( $ts = 0 ) {
2882                 $t = new ConvertibleTimestamp( $ts );
2883                 // Let errors bubble up to avoid putting garbage in the DB
2884                 return $t->getTimestamp( TS_MW );
2885         }
2886
2887         public function timestampOrNull( $ts = null ) {
2888                 if ( is_null( $ts ) ) {
2889                         return null;
2890                 } else {
2891                         return $this->timestamp( $ts );
2892                 }
2893         }
2894
2895         /**
2896          * Take the result from a query, and wrap it in a ResultWrapper if
2897          * necessary. Boolean values are passed through as is, to indicate success
2898          * of write queries or failure.
2899          *
2900          * Once upon a time, Database::query() returned a bare MySQL result
2901          * resource, and it was necessary to call this function to convert it to
2902          * a wrapper. Nowadays, raw database objects are never exposed to external
2903          * callers, so this is unnecessary in external code.
2904          *
2905          * @param bool|ResultWrapper|resource|object $result
2906          * @return bool|ResultWrapper
2907          */
2908         protected function resultObject( $result ) {
2909                 if ( !$result ) {
2910                         return false;
2911                 } elseif ( $result instanceof ResultWrapper ) {
2912                         return $result;
2913                 } elseif ( $result === true ) {
2914                         // Successful write query
2915                         return $result;
2916                 } else {
2917                         return new ResultWrapper( $this, $result );
2918                 }
2919         }
2920
2921         public function ping( &$rtt = null ) {
2922                 // Avoid hitting the server if it was hit recently
2923                 if ( $this->isOpen() && ( microtime( true ) - $this->lastPing ) < self::PING_TTL ) {
2924                         if ( !func_num_args() || $this->mRTTEstimate > 0 ) {
2925                                 $rtt = $this->mRTTEstimate;
2926                                 return true; // don't care about $rtt
2927                         }
2928                 }
2929
2930                 // This will reconnect if possible or return false if not
2931                 $this->clearFlag( self::DBO_TRX, self::REMEMBER_PRIOR );
2932                 $ok = ( $this->query( self::PING_QUERY, __METHOD__, true ) !== false );
2933                 $this->restoreFlags( self::RESTORE_PRIOR );
2934
2935                 if ( $ok ) {
2936                         $rtt = $this->mRTTEstimate;
2937                 }
2938
2939                 return $ok;
2940         }
2941
2942         /**
2943          * @return bool
2944          */
2945         protected function reconnect() {
2946                 $this->closeConnection();
2947                 $this->mOpened = false;
2948                 $this->mConn = false;
2949                 try {
2950                         $this->open( $this->mServer, $this->mUser, $this->mPassword, $this->mDBname );
2951                         $this->lastPing = microtime( true );
2952                         $ok = true;
2953                 } catch ( DBConnectionError $e ) {
2954                         $ok = false;
2955                 }
2956
2957                 return $ok;
2958         }
2959
2960         public function getSessionLagStatus() {
2961                 return $this->getTransactionLagStatus() ?: $this->getApproximateLagStatus();
2962         }
2963
2964         /**
2965          * Get the replica DB lag when the current transaction started
2966          *
2967          * This is useful when transactions might use snapshot isolation
2968          * (e.g. REPEATABLE-READ in innodb), so the "real" lag of that data
2969          * is this lag plus transaction duration. If they don't, it is still
2970          * safe to be pessimistic. This returns null if there is no transaction.
2971          *
2972          * @return array|null ('lag': seconds or false on error, 'since': UNIX timestamp of BEGIN)
2973          * @since 1.27
2974          */
2975         protected function getTransactionLagStatus() {
2976                 return $this->mTrxLevel
2977                         ? [ 'lag' => $this->mTrxReplicaLag, 'since' => $this->trxTimestamp() ]
2978                         : null;
2979         }
2980
2981         /**
2982          * Get a replica DB lag estimate for this server
2983          *
2984          * @return array ('lag': seconds or false on error, 'since': UNIX timestamp of estimate)
2985          * @since 1.27
2986          */
2987         protected function getApproximateLagStatus() {
2988                 return [
2989                         'lag'   => $this->getLBInfo( 'replica' ) ? $this->getLag() : 0,
2990                         'since' => microtime( true )
2991                 ];
2992         }
2993
2994         /**
2995          * Merge the result of getSessionLagStatus() for several DBs
2996          * using the most pessimistic values to estimate the lag of
2997          * any data derived from them in combination
2998          *
2999          * This is information is useful for caching modules
3000          *
3001          * @see WANObjectCache::set()
3002          * @see WANObjectCache::getWithSetCallback()
3003          *
3004          * @param IDatabase $db1
3005          * @param IDatabase ...
3006          * @return array Map of values:
3007          *   - lag: highest lag of any of the DBs or false on error (e.g. replication stopped)
3008          *   - since: oldest UNIX timestamp of any of the DB lag estimates
3009          *   - pending: whether any of the DBs have uncommitted changes
3010          * @since 1.27
3011          */
3012         public static function getCacheSetOptions( IDatabase $db1 ) {
3013                 $res = [ 'lag' => 0, 'since' => INF, 'pending' => false ];
3014                 foreach ( func_get_args() as $db ) {
3015                         /** @var IDatabase $db */
3016                         $status = $db->getSessionLagStatus();
3017                         if ( $status['lag'] === false ) {
3018                                 $res['lag'] = false;
3019                         } elseif ( $res['lag'] !== false ) {
3020                                 $res['lag'] = max( $res['lag'], $status['lag'] );
3021                         }
3022                         $res['since'] = min( $res['since'], $status['since'] );
3023                         $res['pending'] = $res['pending'] ?: $db->writesPending();
3024                 }
3025
3026                 return $res;
3027         }
3028
3029         public function getLag() {
3030                 return 0;
3031         }
3032
3033         public function maxListLen() {
3034                 return 0;
3035         }
3036
3037         public function encodeBlob( $b ) {
3038                 return $b;
3039         }
3040
3041         public function decodeBlob( $b ) {
3042                 if ( $b instanceof Blob ) {
3043                         $b = $b->fetch();
3044                 }
3045                 return $b;
3046         }
3047
3048         public function setSessionOptions( array $options ) {
3049         }
3050
3051         public function sourceFile(
3052                 $filename,
3053                 callable $lineCallback = null,
3054                 callable $resultCallback = null,
3055                 $fname = false,
3056                 callable $inputCallback = null
3057         ) {
3058                 MediaWiki\suppressWarnings();
3059                 $fp = fopen( $filename, 'r' );
3060                 MediaWiki\restoreWarnings();
3061
3062                 if ( false === $fp ) {
3063                         throw new RuntimeException( "Could not open \"{$filename}\".\n" );
3064                 }
3065
3066                 if ( !$fname ) {
3067                         $fname = __METHOD__ . "( $filename )";
3068                 }
3069
3070                 try {
3071                         $error = $this->sourceStream(
3072                                 $fp, $lineCallback, $resultCallback, $fname, $inputCallback );
3073                 } catch ( Exception $e ) {
3074                         fclose( $fp );
3075                         throw $e;
3076                 }
3077
3078                 fclose( $fp );
3079
3080                 return $error;
3081         }
3082
3083         public function setSchemaVars( $vars ) {
3084                 $this->mSchemaVars = $vars;
3085         }
3086
3087         public function sourceStream(
3088                 $fp,
3089                 callable $lineCallback = null,
3090                 callable $resultCallback = null,
3091                 $fname = __METHOD__,
3092                 callable $inputCallback = null
3093         ) {
3094                 $cmd = '';
3095
3096                 while ( !feof( $fp ) ) {
3097                         if ( $lineCallback ) {
3098                                 call_user_func( $lineCallback );
3099                         }
3100
3101                         $line = trim( fgets( $fp ) );
3102
3103                         if ( $line == '' ) {
3104                                 continue;
3105                         }
3106
3107                         if ( '-' == $line[0] && '-' == $line[1] ) {
3108                                 continue;
3109                         }
3110
3111                         if ( $cmd != '' ) {
3112                                 $cmd .= ' ';
3113                         }
3114
3115                         $done = $this->streamStatementEnd( $cmd, $line );
3116
3117                         $cmd .= "$line\n";
3118
3119                         if ( $done || feof( $fp ) ) {
3120                                 $cmd = $this->replaceVars( $cmd );
3121
3122                                 if ( !$inputCallback || call_user_func( $inputCallback, $cmd ) ) {
3123                                         $res = $this->query( $cmd, $fname );
3124
3125                                         if ( $resultCallback ) {
3126                                                 call_user_func( $resultCallback, $res, $this );
3127                                         }
3128
3129                                         if ( false === $res ) {
3130                                                 $err = $this->lastError();
3131
3132                                                 return "Query \"{$cmd}\" failed with error code \"$err\".\n";
3133                                         }
3134                                 }
3135                                 $cmd = '';
3136                         }
3137                 }
3138
3139                 return true;
3140         }
3141
3142         /**
3143          * Called by sourceStream() to check if we've reached a statement end
3144          *
3145          * @param string &$sql SQL assembled so far
3146          * @param string &$newLine New line about to be added to $sql
3147          * @return bool Whether $newLine contains end of the statement
3148          */
3149         public function streamStatementEnd( &$sql, &$newLine ) {
3150                 if ( $this->delimiter ) {
3151                         $prev = $newLine;
3152                         $newLine = preg_replace(
3153                                 '/' . preg_quote( $this->delimiter, '/' ) . '$/', '', $newLine );
3154                         if ( $newLine != $prev ) {
3155                                 return true;
3156                         }
3157                 }
3158
3159                 return false;
3160         }
3161
3162         /**
3163          * Database independent variable replacement. Replaces a set of variables
3164          * in an SQL statement with their contents as given by $this->getSchemaVars().
3165          *
3166          * Supports '{$var}' `{$var}` and / *$var* / (without the spaces) style variables.
3167          *
3168          * - '{$var}' should be used for text and is passed through the database's
3169          *   addQuotes method.
3170          * - `{$var}` should be used for identifiers (e.g. table and database names).
3171          *   It is passed through the database's addIdentifierQuotes method which
3172          *   can be overridden if the database uses something other than backticks.
3173          * - / *_* / or / *$wgDBprefix* / passes the name that follows through the
3174          *   database's tableName method.
3175          * - / *i* / passes the name that follows through the database's indexName method.
3176          * - In all other cases, / *$var* / is left unencoded. Except for table options,
3177          *   its use should be avoided. In 1.24 and older, string encoding was applied.
3178          *
3179          * @param string $ins SQL statement to replace variables in
3180          * @return string The new SQL statement with variables replaced
3181          */
3182         protected function replaceVars( $ins ) {
3183                 $vars = $this->getSchemaVars();
3184                 return preg_replace_callback(
3185                         '!
3186                                 /\* (\$wgDBprefix|[_i]) \*/ (\w*) | # 1-2. tableName, indexName
3187                                 \'\{\$ (\w+) }\'                  | # 3. addQuotes
3188                                 `\{\$ (\w+) }`                    | # 4. addIdentifierQuotes
3189                                 /\*\$ (\w+) \*/                     # 5. leave unencoded
3190                         !x',
3191                         function ( $m ) use ( $vars ) {
3192                                 // Note: Because of <https://bugs.php.net/bug.php?id=51881>,
3193                                 // check for both nonexistent keys *and* the empty string.
3194                                 if ( isset( $m[1] ) && $m[1] !== '' ) {
3195                                         if ( $m[1] === 'i' ) {
3196                                                 return $this->indexName( $m[2] );
3197                                         } else {
3198                                                 return $this->tableName( $m[2] );
3199                                         }
3200                                 } elseif ( isset( $m[3] ) && $m[3] !== '' && array_key_exists( $m[3], $vars ) ) {
3201                                         return $this->addQuotes( $vars[$m[3]] );
3202                                 } elseif ( isset( $m[4] ) && $m[4] !== '' && array_key_exists( $m[4], $vars ) ) {
3203                                         return $this->addIdentifierQuotes( $vars[$m[4]] );
3204                                 } elseif ( isset( $m[5] ) && $m[5] !== '' && array_key_exists( $m[5], $vars ) ) {
3205                                         return $vars[$m[5]];
3206                                 } else {
3207                                         return $m[0];
3208                                 }
3209                         },
3210                         $ins
3211                 );
3212         }
3213
3214         /**
3215          * Get schema variables. If none have been set via setSchemaVars(), then
3216          * use some defaults from the current object.
3217          *
3218          * @return array
3219          */
3220         protected function getSchemaVars() {
3221                 if ( $this->mSchemaVars ) {
3222                         return $this->mSchemaVars;
3223                 } else {
3224                         return $this->getDefaultSchemaVars();
3225                 }
3226         }
3227
3228         /**
3229          * Get schema variables to use if none have been set via setSchemaVars().
3230          *
3231          * Override this in derived classes to provide variables for tables.sql
3232          * and SQL patch files.
3233          *
3234          * @return array
3235          */
3236         protected function getDefaultSchemaVars() {
3237                 return [];
3238         }
3239
3240         public function lockIsFree( $lockName, $method ) {
3241                 return true;
3242         }
3243
3244         public function lock( $lockName, $method, $timeout = 5 ) {
3245                 $this->mNamedLocksHeld[$lockName] = 1;
3246
3247                 return true;
3248         }
3249
3250         public function unlock( $lockName, $method ) {
3251                 unset( $this->mNamedLocksHeld[$lockName] );
3252
3253                 return true;
3254         }
3255
3256         public function getScopedLockAndFlush( $lockKey, $fname, $timeout ) {
3257                 if ( $this->writesOrCallbacksPending() ) {
3258                         // This only flushes transactions to clear snapshots, not to write data
3259                         $fnames = implode( ', ', $this->pendingWriteAndCallbackCallers() );
3260                         throw new DBUnexpectedError(
3261                                 $this,
3262                                 "$fname: Cannot flush pre-lock snapshot because writes are pending ($fnames)."
3263                         );
3264                 }
3265
3266                 if ( !$this->lock( $lockKey, $fname, $timeout ) ) {
3267                         return null;
3268                 }
3269
3270                 $unlocker = new ScopedCallback( function () use ( $lockKey, $fname ) {
3271                         if ( $this->trxLevel() ) {
3272                                 // There is a good chance an exception was thrown, causing any early return
3273                                 // from the caller. Let any error handler get a chance to issue rollback().
3274                                 // If there isn't one, let the error bubble up and trigger server-side rollback.
3275                                 $this->onTransactionResolution(
3276                                         function () use ( $lockKey, $fname ) {
3277                                                 $this->unlock( $lockKey, $fname );
3278                                         },
3279                                         $fname
3280                                 );
3281                         } else {
3282                                 $this->unlock( $lockKey, $fname );
3283                         }
3284                 } );
3285
3286                 $this->commit( $fname, self::FLUSHING_INTERNAL );
3287
3288                 return $unlocker;
3289         }
3290
3291         public function namedLocksEnqueue() {
3292                 return false;
3293         }
3294
3295         /**
3296          * Lock specific tables
3297          *
3298          * @param array $read Array of tables to lock for read access
3299          * @param array $write Array of tables to lock for write access
3300          * @param string $method Name of caller
3301          * @param bool $lowPriority Whether to indicate writes to be LOW PRIORITY
3302          * @return bool
3303          */
3304         public function lockTables( $read, $write, $method, $lowPriority = true ) {
3305                 return true;
3306         }
3307
3308         /**
3309          * Unlock specific tables
3310          *
3311          * @param string $method The caller
3312          * @return bool
3313          */
3314         public function unlockTables( $method ) {
3315                 return true;
3316         }
3317
3318         /**
3319          * Delete a table
3320          * @param string $tableName
3321          * @param string $fName
3322          * @return bool|ResultWrapper
3323          * @since 1.18
3324          */
3325         public function dropTable( $tableName, $fName = __METHOD__ ) {
3326                 if ( !$this->tableExists( $tableName, $fName ) ) {
3327                         return false;
3328                 }
3329                 $sql = "DROP TABLE " . $this->tableName( $tableName ) . " CASCADE";
3330
3331                 return $this->query( $sql, $fName );
3332         }
3333
3334         public function getInfinity() {
3335                 return 'infinity';
3336         }
3337
3338         public function encodeExpiry( $expiry ) {
3339                 return ( $expiry == '' || $expiry == 'infinity' || $expiry == $this->getInfinity() )
3340                         ? $this->getInfinity()
3341                         : $this->timestamp( $expiry );
3342         }
3343
3344         public function decodeExpiry( $expiry, $format = TS_MW ) {
3345                 if ( $expiry == '' || $expiry == 'infinity' || $expiry == $this->getInfinity() ) {
3346                         return 'infinity';
3347                 }
3348
3349                 return ConvertibleTimestamp::convert( $format, $expiry );
3350         }
3351
3352         public function setBigSelects( $value = true ) {
3353                 // no-op
3354         }
3355
3356         public function isReadOnly() {
3357                 return ( $this->getReadOnlyReason() !== false );
3358         }
3359
3360         /**
3361          * @return string|bool Reason this DB is read-only or false if it is not
3362          */
3363         protected function getReadOnlyReason() {
3364                 $reason = $this->getLBInfo( 'readOnlyReason' );
3365
3366                 return is_string( $reason ) ? $reason : false;
3367         }
3368
3369         public function setTableAliases( array $aliases ) {
3370                 $this->tableAliases = $aliases;
3371         }
3372
3373         /**
3374          * @return bool Whether a DB user is required to access the DB
3375          * @since 1.28
3376          */
3377         protected function requiresDatabaseUser() {
3378                 return true;
3379         }
3380
3381         /**
3382          * Get the underlying binding handle, mConn
3383          *
3384          * Makes sure that mConn is set (disconnects and ping() failure can unset it).
3385          * This catches broken callers than catch and ignore disconnection exceptions.
3386          * Unlike checking isOpen(), this is safe to call inside of open().
3387          *
3388          * @return resource|object
3389          * @throws DBUnexpectedError
3390          * @since 1.26
3391          */
3392         protected function getBindingHandle() {
3393                 if ( !$this->mConn ) {
3394                         throw new DBUnexpectedError(
3395                                 $this,
3396                                 'DB connection was already closed or the connection dropped.'
3397                         );
3398                 }
3399
3400                 return $this->mConn;
3401         }
3402
3403         /**
3404          * @since 1.19
3405          * @return string
3406          */
3407         public function __toString() {
3408                 return (string)$this->mConn;
3409         }
3410
3411         /**
3412          * Make sure that copies do not share the same client binding handle
3413          * @throws DBConnectionError
3414          */
3415         public function __clone() {
3416                 $this->connLogger->warning(
3417                         "Cloning " . get_class( $this ) . " is not recomended; forking connection:\n" .
3418                         ( new RuntimeException() )->getTraceAsString()
3419                 );
3420
3421                 if ( $this->isOpen() ) {
3422                         // Open a new connection resource without messing with the old one
3423                         $this->mOpened = false;
3424                         $this->mConn = false;
3425                         $this->mTrxEndCallbacks = []; // don't copy
3426                         $this->handleSessionLoss(); // no trx or locks anymore
3427                         $this->open( $this->mServer, $this->mUser, $this->mPassword, $this->mDBname );
3428                         $this->lastPing = microtime( true );
3429                 }
3430         }
3431
3432         /**
3433          * Called by serialize. Throw an exception when DB connection is serialized.
3434          * This causes problems on some database engines because the connection is
3435          * not restored on unserialize.
3436          */
3437         public function __sleep() {
3438                 throw new RuntimeException( 'Database serialization may cause problems, since ' .
3439                         'the connection is not restored on wakeup.' );
3440         }
3441
3442         /**
3443          * Run a few simple sanity checks and close dangling connections
3444          */
3445         public function __destruct() {
3446                 if ( $this->mTrxLevel && $this->mTrxDoneWrites ) {
3447                         trigger_error( "Uncommitted DB writes (transaction from {$this->mTrxFname})." );
3448                 }
3449
3450                 $danglingWriters = $this->pendingWriteAndCallbackCallers();
3451                 if ( $danglingWriters ) {
3452                         $fnames = implode( ', ', $danglingWriters );
3453                         trigger_error( "DB transaction writes or callbacks still pending ($fnames)." );
3454                 }
3455
3456                 if ( $this->mConn ) {
3457                         // Avoid connection leaks for sanity. Normally, resources close at script completion.
3458                         // The connection might already be closed in zend/hhvm by now, so suppress warnings.
3459                         \MediaWiki\suppressWarnings();
3460                         $this->closeConnection();
3461                         \MediaWiki\restoreWarnings();
3462                         $this->mConn = false;
3463                         $this->mOpened = false;
3464                 }
3465         }
3466 }
3467
3468 class_alias( 'Database', 'DatabaseBase' );