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
  29 /**
  30  * Database abstraction object
  31  * @ingroup Database
  32  */
  33 abstract class Database implements IDatabase, LoggerAwareInterface {
  34         /** Number of times to re-try an operation in case of deadlock */
  35         const DEADLOCK_TRIES = 4;
  36         /** Minimum time to wait before retry, in microseconds */
  37         const DEADLOCK_DELAY_MIN = 500000;
  38         /** Maximum time to wait before retry */
  39         const DEADLOCK_DELAY_MAX = 1500000;
  40
  41         /** How long before it is worth doing a dummy query to test the connection */
  42         const PING_TTL = 1.0;
  43         const PING_QUERY = 'SELECT 1 AS ping';
  44
  45         const TINY_WRITE_SEC = .010;
  46         const SLOW_WRITE_SEC = .500;
  47         const SMALL_WRITE_ROWS = 100;
  48
  49         /** @var string SQL query */
  50         protected $mLastQuery = '';
  51         /** @var bool */
  52         protected $mDoneWrites = false;
  53         /** @var string|bool */
  54         protected $mPHPError = false;
  55         /** @var string */
  56         protected $mServer;
  57         /** @var string */
  58         protected $mUser;
  59         /** @var string */
  60         protected $mPassword;
  61         /** @var string */
  62         protected $mDBname;
  63         /** @var array[] $aliases Map of (table => (dbname, schema, prefix) map) */
  64         protected $tableAliases = [];
  65         /** @var bool Whether this PHP instance is for a CLI script */
  66         protected $cliMode;
  67         /** @var string Agent name for query profiling */
  68         protected $agent;
  69
  70         /** @var BagOStuff APC cache */
  71         protected $srvCache;
  72         /** @var LoggerInterface */
  73         protected $connLogger;
  74         /** @var LoggerInterface */
  75         protected $queryLogger;
  76         /** @var callback Error logging callback */
  77         protected $errorLogger;
  78
  79         /** @var resource Database connection */
  80         protected $mConn = null;
  81         /** @var bool */
  82         protected $mOpened = false;
  83
  84         /** @var array[] List of (callable, method name) */
  85         protected $mTrxIdleCallbacks = [];
  86         /** @var array[] List of (callable, method name) */
  87         protected $mTrxPreCommitCallbacks = [];
  88         /** @var array[] List of (callable, method name) */
  89         protected $mTrxEndCallbacks = [];
  90         /** @var callable[] Map of (name => callable) */
  91         protected $mTrxRecurringCallbacks = [];
  92         /** @var bool Whether to suppress triggering of transaction end callbacks */
  93         protected $mTrxEndCallbacksSuppressed = false;
  94
  95         /** @var string */
  96         protected $mTablePrefix = '';
  97         /** @var string */
  98         protected $mSchema = '';
  99         /** @var integer */
 100         protected $mFlags;
 101         /** @var array */
 102         protected $mLBInfo = [];
 103         /** @var bool|null */
 104         protected $mDefaultBigSelects = null;
 105         /** @var array|bool */
 106         protected $mSchemaVars = false;
 107         /** @var array */
 108         protected $mSessionVars = [];
 109         /** @var array|null */
 110         protected $preparedArgs;
 111         /** @var string|bool|null Stashed value of html_errors INI setting */
 112         protected $htmlErrors;
 113         /** @var string */
 114         protected $delimiter = ';';
 115         /** @var DatabaseDomain */
 116         protected $currentDomain;
 117
 118         /**
 119          * Either 1 if a transaction is active or 0 otherwise.
 120          * The other Trx fields may not be meaningfull if this is 0.
 121          *
 122          * @var int
 123          */
 124         protected $mTrxLevel = 0;
 125         /**
 126          * Either a short hexidecimal string if a transaction is active or ""
 127          *
 128          * @var string
 129          * @see DatabaseBase::mTrxLevel
 130          */
 131         protected $mTrxShortId = '';
 132         /**
 133          * The UNIX time that the transaction started. Callers can assume that if
 134          * snapshot isolation is used, then the data is *at least* up to date to that
 135          * point (possibly more up-to-date since the first SELECT defines the snapshot).
 136          *
 137          * @var float|null
 138          * @see DatabaseBase::mTrxLevel
 139          */
 140         private $mTrxTimestamp = null;
 141         /** @var float Lag estimate at the time of BEGIN */
 142         private $mTrxReplicaLag = null;
 143         /**
 144          * Remembers the function name given for starting the most recent transaction via begin().
 145          * Used to provide additional context for error reporting.
 146          *
 147          * @var string
 148          * @see DatabaseBase::mTrxLevel
 149          */
 150         private $mTrxFname = null;
 151         /**
 152          * Record if possible write queries were done in the last transaction started
 153          *
 154          * @var bool
 155          * @see DatabaseBase::mTrxLevel
 156          */
 157         private $mTrxDoneWrites = false;
 158         /**
 159          * Record if the current transaction was started implicitly due to DBO_TRX being set.
 160          *
 161          * @var bool
 162          * @see DatabaseBase::mTrxLevel
 163          */
 164         private $mTrxAutomatic = false;
 165         /**
 166          * Array of levels of atomicity within transactions
 167          *
 168          * @var array
 169          */
 170         private $mTrxAtomicLevels = [];
 171         /**
 172          * Record if the current transaction was started implicitly by DatabaseBase::startAtomic
 173          *
 174          * @var bool
 175          */
 176         private $mTrxAutomaticAtomic = false;
 177         /**
 178          * Track the write query callers of the current transaction
 179          *
 180          * @var string[]
 181          */
 182         private $mTrxWriteCallers = [];
 183         /**
 184          * @var float Seconds spent in write queries for the current transaction
 185          */
 186         private $mTrxWriteDuration = 0.0;
 187         /**
 188          * @var integer Number of write queries for the current transaction
 189          */
 190         private $mTrxWriteQueryCount = 0;
 191         /**
 192          * @var float Like mTrxWriteQueryCount but excludes lock-bound, easy to replicate, queries
 193          */
 194         private $mTrxWriteAdjDuration = 0.0;
 195         /**
 196          * @var integer Number of write queries counted in mTrxWriteAdjDuration
 197          */
 198         private $mTrxWriteAdjQueryCount = 0;
 199         /**
 200          * @var float RTT time estimate
 201          */
 202         private $mRTTEstimate = 0.0;
 203
 204         /** @var array Map of (name => 1) for locks obtained via lock() */
 205         private $mNamedLocksHeld = [];
 206
 207         /** @var IDatabase|null Lazy handle to the master DB this server replicates from */
 208         private $lazyMasterHandle;
 209
 210         /**
 211          * @since 1.21
 212          * @var resource File handle for upgrade
 213          */
 214         protected $fileHandle = null;
 215
 216         /**
 217          * @since 1.22
 218          * @var string[] Process cache of VIEWs names in the database
 219          */
 220         protected $allViews = null;
 221
 222         /** @var float UNIX timestamp */
 223         protected $lastPing = 0.0;
 224
 225         /** @var int[] Prior mFlags values */
 226         private $priorFlags = [];
 227
 228         /** @var object|string Class name or object With profileIn/profileOut methods */
 229         protected $profiler;
 230         /** @var TransactionProfiler */
 231         protected $trxProfiler;
 232
 233         /**
 234          * Constructor and database handle and attempt to connect to the DB server
 235          *
 236          * IDatabase classes should not be constructed directly in external
 237          * code. Database::factory() should be used instead.
 238          *
 239          * @param array $params Parameters passed from Database::factory()
 240          */
 241         function __construct( array $params ) {
 242                 $server = $params['host'];
 243                 $user = $params['user'];
 244                 $password = $params['password'];
 245                 $dbName = $params['dbname'];
 246                 $flags = $params['flags'];
 247
 248                 $this->mSchema = $params['schema'];
 249                 $this->mTablePrefix = $params['tablePrefix'];
 250
 251                 $this->cliMode = isset( $params['cliMode'] )
 252                         ? $params['cliMode']
 253                         : ( PHP_SAPI === 'cli' );
 254                 $this->agent = isset( $params['agent'] )
 255                         ? str_replace( '/', '-', $params['agent'] ) // escape for comment
 256                         : '';
 257
 258                 $this->mFlags = $flags;
 259                 if ( $this->mFlags & DBO_DEFAULT ) {
 260                         if ( $this->cliMode ) {
 261                                 $this->mFlags &= ~DBO_TRX;
 262                         } else {
 263                                 $this->mFlags |= DBO_TRX;
 264                         }
 265                 }
 266
 267                 $this->mSessionVars = $params['variables'];
 268
 269                 $this->srvCache = isset( $params['srvCache'] )
 270                         ? $params['srvCache']
 271                         : new HashBagOStuff();
 272
 273                 $this->profiler = isset( $params['profiler'] ) ? $params['profiler'] : null;
 274                 $this->trxProfiler = isset( $params['trxProfiler'] )
 275                         ? $params['trxProfiler']
 276                         : new TransactionProfiler();
 277                 $this->connLogger = isset( $params['connLogger'] )
 278                         ? $params['connLogger']
 279                         : new \Psr\Log\NullLogger();
 280                 $this->queryLogger = isset( $params['queryLogger'] )
 281                         ? $params['queryLogger']
 282                         : new \Psr\Log\NullLogger();
 283
 284                 if ( $user ) {
 285                         $this->open( $server, $user, $password, $dbName );
 286                 } elseif ( $this->requiresDatabaseUser() ) {
 287                         throw new InvalidArgumentException( "No database user provided." );
 288                 }
 289
 290                 // Set the domain object after open() sets the relevant fields
 291                 $this->currentDomain = ( $this->mDBname != '' )
 292                         ? new DatabaseDomain( $this->mDBname, null, $this->mTablePrefix )
 293                         : DatabaseDomain::newUnspecified();
 294         }
 295
 296         /**
 297          * Construct a Database subclass instance given a database type and parameters
 298          *
 299          * This also connects to the database immediately upon object construction
 300          *
 301          * @param string $dbType A possible DB type (sqlite, mysql, postgres)
 302          * @param array $p Parameter map with keys:
 303          *   - host : The hostname of the DB server
 304          *   - user : The name of the database user the client operates under
 305          *   - password : The password for the database user
 306          *   - dbname : The name of the database to use where queries do not specify one.
 307          *      The database must exist or an error might be thrown. Setting this to the empty string
 308          *      will avoid any such errors and make the handle have no implicit database scope. This is
 309          *      useful for queries like SHOW STATUS, CREATE DATABASE, or DROP DATABASE. Note that a
 310          *      "database" in Postgres is rougly equivalent to an entire MySQL server. This the domain
 311          *      in which user names and such are defined, e.g. users are database-specific in Postgres.
 312          *   - schema : The database schema to use (if supported). A "schema" in Postgres is roughly
 313          *      equivalent to a "database" in MySQL. Note that MySQL and SQLite do not use schemas.
 314          *   - tablePrefix : Optional table prefix that is implicitly added on to all table names
 315          *      recognized in queries. This can be used in place of schemas for handle site farms.
 316          *   - flags : Optional bitfield of DBO_* constants that define connection, protocol,
 317          *      buffering, and transaction behavior. It is STRONGLY adviced to leave the DBO_DEFAULT
 318          *      flag in place UNLESS this this database simply acts as a key/value store.
 319          *   - driver: Optional name of a specific DB client driver. For MySQL, there is the old
 320          *      'mysql' driver and the newer 'mysqli' driver.
 321          *   - variables: Optional map of session variables to set after connecting. This can be
 322          *      used to adjust lock timeouts or encoding modes and the like.
 323          *   - connLogger: Optional PSR-3 logger interface instance.
 324          *   - queryLogger: Optional PSR-3 logger interface instance.
 325          *   - profiler: Optional class name or object with profileIn()/profileOut() methods.
 326          *      These will be called in query(), using a simplified version of the SQL that also
 327          *      includes the agent as a SQL comment.
 328          *   - trxProfiler: Optional TransactionProfiler instance.
 329          *   - errorLogger: Optional callback that takes an Exception and logs it.
 330          *   - cliMode: Whether to consider the execution context that of a CLI script.
 331          *   - agent: Optional name used to identify the end-user in query profiling/logging.
 332          *   - srvCache: Optional BagOStuff instance to an APC-style cache.
 333          * @return Database|null If the database driver or extension cannot be found
 334          * @throws InvalidArgumentException If the database driver or extension cannot be found
 335          * @since 1.18
 336          */
 337         final public static function factory( $dbType, $p = [] ) {
 338                 static $canonicalDBTypes = [
 339                         'mysql' => [ 'mysqli', 'mysql' ],
 340                         'postgres' => [],
 341                         'sqlite' => [],
 342                         'oracle' => [],
 343                         'mssql' => [],
 344                 ];
 345
 346                 $driver = false;
 347                 $dbType = strtolower( $dbType );
 348                 if ( isset( $canonicalDBTypes[$dbType] ) && $canonicalDBTypes[$dbType] ) {
 349                         $possibleDrivers = $canonicalDBTypes[$dbType];
 350                         if ( !empty( $p['driver'] ) ) {
 351                                 if ( in_array( $p['driver'], $possibleDrivers ) ) {
 352                                         $driver = $p['driver'];
 353                                 } else {
 354                                         throw new InvalidArgumentException( __METHOD__ .
 355                                                 " type '$dbType' does not support driver '{$p['driver']}'" );
 356                                 }
 357                         } else {
 358                                 foreach ( $possibleDrivers as $posDriver ) {
 359                                         if ( extension_loaded( $posDriver ) ) {
 360                                                 $driver = $posDriver;
 361                                                 break;
 362                                         }
 363                                 }
 364                         }
 365                 } else {
 366                         $driver = $dbType;
 367                 }
 368                 if ( $driver === false ) {
 369                         throw new InvalidArgumentException( __METHOD__ .
 370                                 " no viable database extension found for type '$dbType'" );
 371                 }
 372
 373                 $class = 'Database' . ucfirst( $driver );
 374                 if ( class_exists( $class ) && is_subclass_of( $class, 'IDatabase' ) ) {
 375                         // Resolve some defaults for b/c
 376                         $p['host'] = isset( $p['host'] ) ? $p['host'] : false;
 377                         $p['user'] = isset( $p['user'] ) ? $p['user'] : false;
 378                         $p['password'] = isset( $p['password'] ) ? $p['password'] : false;
 379                         $p['dbname'] = isset( $p['dbname'] ) ? $p['dbname'] : false;
 380                         $p['flags'] = isset( $p['flags'] ) ? $p['flags'] : 0;
 381                         $p['variables'] = isset( $p['variables'] ) ? $p['variables'] : [];
 382                         $p['tablePrefix'] = isset( $p['tablePrefix'] ) ? $p['tablePrefix'] : '';
 383                         $p['schema'] = isset( $p['schema'] ) ? $p['schema'] : '';
 384                         $p['foreign'] = isset( $p['foreign'] ) ? $p['foreign'] : false;
 385
 386                         $conn = new $class( $p );
 387                         if ( isset( $p['connLogger'] ) ) {
 388                                 $conn->connLogger = $p['connLogger'];
 389                         }
 390                         if ( isset( $p['queryLogger'] ) ) {
 391                                 $conn->queryLogger = $p['queryLogger'];
 392                         }
 393                         if ( isset( $p['errorLogger'] ) ) {
 394                                 $conn->errorLogger = $p['errorLogger'];
 395                         } else {
 396                                 $conn->errorLogger = function ( Exception $e ) {
 397                                         trigger_error( get_class( $e ) . ': ' . $e->getMessage(), E_WARNING );
 398                                 };
 399                         }
 400                 } else {
 401                         $conn = null;
 402                 }
 403
 404                 return $conn;
 405         }
 406
 407         public function setLogger( LoggerInterface $logger ) {
 408                 $this->queryLogger = $logger;
 409         }
 410
 411         public function getServerInfo() {
 412                 return $this->getServerVersion();
 413         }
 414
 415         public function bufferResults( $buffer = null ) {
 416                 $res = !$this->getFlag( DBO_NOBUFFER );
 417                 if ( $buffer !== null ) {
 418                         $buffer ? $this->clearFlag( DBO_NOBUFFER ) : $this->setFlag( DBO_NOBUFFER );
 419                 }
 420
 421                 return $res;
 422         }
 423
 424         /**
 425          * Turns on (false) or off (true) the automatic generation and sending
 426          * of a "we're sorry, but there has been a database error" page on
 427          * database errors. Default is on (false). When turned off, the
 428          * code should use lastErrno() and lastError() to handle the
 429          * situation as appropriate.
 430          *
 431          * Do not use this function outside of the Database classes.
 432          *
 433          * @param null|bool $ignoreErrors
 434          * @return bool The previous value of the flag.
 435          */
 436         protected function ignoreErrors( $ignoreErrors = null ) {
 437                 $res = $this->getFlag( DBO_IGNORE );
 438                 if ( $ignoreErrors !== null ) {
 439                         $ignoreErrors ? $this->setFlag( DBO_IGNORE ) : $this->clearFlag( DBO_IGNORE );
 440                 }
 441
 442                 return $res;
 443         }
 444
 445         public function trxLevel() {
 446                 return $this->mTrxLevel;
 447         }
 448
 449         public function trxTimestamp() {
 450                 return $this->mTrxLevel ? $this->mTrxTimestamp : null;
 451         }
 452
 453         public function tablePrefix( $prefix = null ) {
 454                 $old = $this->mTablePrefix;
 455                 if ( $prefix !== null ) {
 456                         $this->mTablePrefix = $prefix;
 457                         $this->currentDomain = ( $this->mDBname != '' )
 458                                 ? new DatabaseDomain( $this->mDBname, null, $this->mTablePrefix )
 459                                 : DatabaseDomain::newUnspecified();
 460                 }
 461
 462                 return $old;
 463         }
 464
 465         public function dbSchema( $schema = null ) {
 466                 $old = $this->mSchema;
 467                 if ( $schema !== null ) {
 468                         $this->mSchema = $schema;
 469                 }
 470
 471                 return $old;
 472         }
 473
 474         /**
 475          * Set the filehandle to copy write statements to.
 476          *
 477          * @param resource $fh File handle
 478          */
 479         public function setFileHandle( $fh ) {
 480                 $this->fileHandle = $fh;
 481         }
 482
 483         public function getLBInfo( $name = null ) {
 484                 if ( is_null( $name ) ) {
 485                         return $this->mLBInfo;
 486                 } else {
 487                         if ( array_key_exists( $name, $this->mLBInfo ) ) {
 488                                 return $this->mLBInfo[$name];
 489                         } else {
 490                                 return null;
 491                         }
 492                 }
 493         }
 494
 495         public function setLBInfo( $name, $value = null ) {
 496                 if ( is_null( $value ) ) {
 497                         $this->mLBInfo = $name;
 498                 } else {
 499                         $this->mLBInfo[$name] = $value;
 500                 }
 501         }
 502
 503         public function setLazyMasterHandle( IDatabase $conn ) {
 504                 $this->lazyMasterHandle = $conn;
 505         }
 506
 507         /**
 508          * @return IDatabase|null
 509          * @see setLazyMasterHandle()
 510          * @since 1.27
 511          */
 512         public function getLazyMasterHandle() {
 513                 return $this->lazyMasterHandle;
 514         }
 515
 516         public function implicitGroupby() {
 517                 return true;
 518         }
 519
 520         public function implicitOrderby() {
 521                 return true;
 522         }
 523
 524         public function lastQuery() {
 525                 return $this->mLastQuery;
 526         }
 527
 528         public function doneWrites() {
 529                 return (bool)$this->mDoneWrites;
 530         }
 531
 532         public function lastDoneWrites() {
 533                 return $this->mDoneWrites ?: false;
 534         }
 535
 536         public function writesPending() {
 537                 return $this->mTrxLevel && $this->mTrxDoneWrites;
 538         }
 539
 540         public function writesOrCallbacksPending() {
 541                 return $this->mTrxLevel && (
 542                         $this->mTrxDoneWrites || $this->mTrxIdleCallbacks || $this->mTrxPreCommitCallbacks
 543                 );
 544         }
 545
 546         public function pendingWriteQueryDuration( $type = self::ESTIMATE_TOTAL ) {
 547                 if ( !$this->mTrxLevel ) {
 548                         return false;
 549                 } elseif ( !$this->mTrxDoneWrites ) {
 550                         return 0.0;
 551                 }
 552
 553                 switch ( $type ) {
 554                         case self::ESTIMATE_DB_APPLY:
 555                                 $this->ping( $rtt );
 556                                 $rttAdjTotal = $this->mTrxWriteAdjQueryCount * $rtt;
 557                                 $applyTime = max( $this->mTrxWriteAdjDuration - $rttAdjTotal, 0 );
 558                                 // For omitted queries, make them count as something at least
 559                                 $omitted = $this->mTrxWriteQueryCount - $this->mTrxWriteAdjQueryCount;
 560                                 $applyTime += self::TINY_WRITE_SEC * $omitted;
 561
 562                                 return $applyTime;
 563                         default: // everything
 564                                 return $this->mTrxWriteDuration;
 565                 }
 566         }
 567
 568         public function pendingWriteCallers() {
 569                 return $this->mTrxLevel ? $this->mTrxWriteCallers : [];
 570         }
 571
 572         protected function pendingWriteAndCallbackCallers() {
 573                 if ( !$this->mTrxLevel ) {
 574                         return [];
 575                 }
 576
 577                 $fnames = $this->mTrxWriteCallers;
 578                 foreach ( [
 579                         $this->mTrxIdleCallbacks,
 580                         $this->mTrxPreCommitCallbacks,
 581                         $this->mTrxEndCallbacks
 582                 ] as $callbacks ) {
 583                         foreach ( $callbacks as $callback ) {
 584                                 $fnames[] = $callback[1];
 585                         }
 586                 }
 587
 588                 return $fnames;
 589         }
 590
 591         public function isOpen() {
 592                 return $this->mOpened;
 593         }
 594
 595         public function setFlag( $flag, $remember = self::REMEMBER_NOTHING ) {
 596                 if ( $remember === self::REMEMBER_PRIOR ) {
 597                         array_push( $this->priorFlags, $this->mFlags );
 598                 }
 599                 $this->mFlags |= $flag;
 600         }
 601
 602         public function clearFlag( $flag, $remember = self::REMEMBER_NOTHING ) {
 603                 if ( $remember === self::REMEMBER_PRIOR ) {
 604                         array_push( $this->priorFlags, $this->mFlags );
 605                 }
 606                 $this->mFlags &= ~$flag;
 607         }
 608
 609         public function restoreFlags( $state = self::RESTORE_PRIOR ) {
 610                 if ( !$this->priorFlags ) {
 611                         return;
 612                 }
 613
 614                 if ( $state === self::RESTORE_INITIAL ) {
 615                         $this->mFlags = reset( $this->priorFlags );
 616                         $this->priorFlags = [];
 617                 } else {
 618                         $this->mFlags = array_pop( $this->priorFlags );
 619                 }
 620         }
 621
 622         public function getFlag( $flag ) {
 623                 return !!( $this->mFlags & $flag );
 624         }
 625
 626         public function getProperty( $name ) {
 627                 return $this->$name;
 628         }
 629
 630         public function getDomainID() {
 631                 return $this->currentDomain->getId();
 632         }
 633
 634         final public function getWikiID() {
 635                 return $this->getDomainID();
 636         }
 637
 638         /**
 639          * Get information about an index into an object
 640          * @param string $table Table name
 641          * @param string $index Index name
 642          * @param string $fname Calling function name
 643          * @return mixed Database-specific index description class or false if the index does not exist
 644          */
 645         abstract function indexInfo( $table, $index, $fname = __METHOD__ );
 646
 647         /**
 648          * Wrapper for addslashes()
 649          *
 650          * @param string $s String to be slashed.
 651          * @return string Slashed string.
 652          */
 653         abstract function strencode( $s );
 654
 655         protected function installErrorHandler() {
 656                 $this->mPHPError = false;
 657                 $this->htmlErrors = ini_set( 'html_errors', '0' );
 658                 set_error_handler( [ $this, 'connectionerrorLogger' ] );
 659         }
 660
 661         /**
 662          * @return bool|string
 663          */
 664         protected function restoreErrorHandler() {
 665                 restore_error_handler();
 666                 if ( $this->htmlErrors !== false ) {
 667                         ini_set( 'html_errors', $this->htmlErrors );
 668                 }
 669                 if ( $this->mPHPError ) {
 670                         $error = preg_replace( '!\[<a.*</a>\]!', '', $this->mPHPError );
 671                         $error = preg_replace( '!^.*?:\s?(.*)$!', '$1', $error );
 672
 673                         return $error;
 674                 } else {
 675                         return false;
 676                 }
 677         }
 678
 679         /**
 680          * @param int $errno
 681          * @param string $errstr
 682          */
 683         public function connectionerrorLogger( $errno, $errstr ) {
 684                 $this->mPHPError = $errstr;
 685         }
 686
 687         /**
 688          * Create a log context to pass to PSR-3 logger functions.
 689          *
 690          * @param array $extras Additional data to add to context
 691          * @return array
 692          */
 693         protected function getLogContext( array $extras = [] ) {
 694                 return array_merge(
 695                         [
 696                                 'db_server' => $this->mServer,
 697                                 'db_name' => $this->mDBname,
 698                                 'db_user' => $this->mUser,
 699                         ],
 700                         $extras
 701                 );
 702         }
 703
 704         public function close() {
 705                 if ( $this->mConn ) {
 706                         if ( $this->trxLevel() ) {
 707                                 $this->commit( __METHOD__, self::FLUSHING_INTERNAL );
 708                         }
 709
 710                         $closed = $this->closeConnection();
 711                         $this->mConn = false;
 712                 } elseif ( $this->mTrxIdleCallbacks || $this->mTrxEndCallbacks ) { // sanity
 713                         throw new RuntimeException( "Transaction callbacks still pending." );
 714                 } else {
 715                         $closed = true;
 716                 }
 717                 $this->mOpened = false;
 718
 719                 return $closed;
 720         }
 721
 722         /**
 723          * Make sure isOpen() returns true as a sanity check
 724          *
 725          * @throws DBUnexpectedError
 726          */
 727         protected function assertOpen() {
 728                 if ( !$this->isOpen() ) {
 729                         throw new DBUnexpectedError( $this, "DB connection was already closed." );
 730                 }
 731         }
 732
 733         /**
 734          * Closes underlying database connection
 735          * @since 1.20
 736          * @return bool Whether connection was closed successfully
 737          */
 738         abstract protected function closeConnection();
 739
 740         function reportConnectionError( $error = 'Unknown error' ) {
 741                 $myError = $this->lastError();
 742                 if ( $myError ) {
 743                         $error = $myError;
 744                 }
 745
 746                 # New method
 747                 throw new DBConnectionError( $this, $error );
 748         }
 749
 750         /**
 751          * The DBMS-dependent part of query()
 752          *
 753          * @param string $sql SQL query.
 754          * @return ResultWrapper|bool Result object to feed to fetchObject,
 755          *   fetchRow, ...; or false on failure
 756          */
 757         abstract protected function doQuery( $sql );
 758
 759         /**
 760          * Determine whether a query writes to the DB.
 761          * Should return true if unsure.
 762          *
 763          * @param string $sql
 764          * @return bool
 765          */
 766         protected function isWriteQuery( $sql ) {
 767                 return !preg_match(
 768                         '/^(?:SELECT|BEGIN|ROLLBACK|COMMIT|SET|SHOW|EXPLAIN|\(SELECT)\b/i', $sql );
 769         }
 770
 771         /**
 772          * @param $sql
 773          * @return string|null
 774          */
 775         protected function getQueryVerb( $sql ) {
 776                 return preg_match( '/^\s*([a-z]+)/i', $sql, $m ) ? strtoupper( $m[1] ) : null;
 777         }
 778
 779         /**
 780          * Determine whether a SQL statement is sensitive to isolation level.
 781          * A SQL statement is considered transactable if its result could vary
 782          * depending on the transaction isolation level. Operational commands
 783          * such as 'SET' and 'SHOW' are not considered to be transactable.
 784          *
 785          * @param string $sql
 786          * @return bool
 787          */
 788         protected function isTransactableQuery( $sql ) {
 789                 $verb = $this->getQueryVerb( $sql );
 790                 return !in_array( $verb, [ 'BEGIN', 'COMMIT', 'ROLLBACK', 'SHOW', 'SET' ], true );
 791         }
 792
 793         public function query( $sql, $fname = __METHOD__, $tempIgnore = false ) {
 794                 $priorWritesPending = $this->writesOrCallbacksPending();
 795                 $this->mLastQuery = $sql;
 796
 797                 $isWrite = $this->isWriteQuery( $sql );
 798                 if ( $isWrite ) {
 799                         $reason = $this->getReadOnlyReason();
 800                         if ( $reason !== false ) {
 801                                 throw new DBReadOnlyError( $this, "Database is read-only: $reason" );
 802                         }
 803                         # Set a flag indicating that writes have been done
 804                         $this->mDoneWrites = microtime( true );
 805                 }
 806
 807                 // Add trace comment to the begin of the sql string, right after the operator.
 808                 // Or, for one-word queries (like "BEGIN" or COMMIT") add it to the end (bug 42598)
 809                 $commentedSql = preg_replace( '/\s|$/', " /* $fname {$this->agent} */ ", $sql, 1 );
 810
 811                 # Start implicit transactions that wrap the request if DBO_TRX is enabled
 812                 if ( !$this->mTrxLevel && $this->getFlag( DBO_TRX )
 813                         && $this->isTransactableQuery( $sql )
 814                 ) {
 815                         $this->begin( __METHOD__ . " ($fname)", self::TRANSACTION_INTERNAL );
 816                         $this->mTrxAutomatic = true;
 817                 }
 818
 819                 # Keep track of whether the transaction has write queries pending
 820                 if ( $this->mTrxLevel && !$this->mTrxDoneWrites && $isWrite ) {
 821                         $this->mTrxDoneWrites = true;
 822                         $this->trxProfiler->transactionWritingIn(
 823                                 $this->mServer, $this->mDBname, $this->mTrxShortId );
 824                 }
 825
 826                 if ( $this->getFlag( DBO_DEBUG ) ) {
 827                         $this->queryLogger->debug( "{$this->mDBname} {$commentedSql}" );
 828                 }
 829
 830                 # Avoid fatals if close() was called
 831                 $this->assertOpen();
 832
 833                 # Send the query to the server
 834                 $ret = $this->doProfiledQuery( $sql, $commentedSql, $isWrite, $fname );
 835
 836                 # Try reconnecting if the connection was lost
 837                 if ( false === $ret && $this->wasErrorReissuable() ) {
 838                         $recoverable = $this->canRecoverFromDisconnect( $sql, $priorWritesPending );
 839                         # Stash the last error values before anything might clear them
 840                         $lastError = $this->lastError();
 841                         $lastErrno = $this->lastErrno();
 842                         # Update state tracking to reflect transaction loss due to disconnection
 843                         $this->handleTransactionLoss();
 844                         if ( $this->reconnect() ) {
 845                                 $msg = __METHOD__ . ": lost connection to {$this->getServer()}; reconnected";
 846                                 $this->connLogger->warning( $msg );
 847                                 $this->queryLogger->warning(
 848                                         "$msg:\n" . ( new RuntimeException() )->getTraceAsString() );
 849
 850                                 if ( !$recoverable ) {
 851                                         # Callers may catch the exception and continue to use the DB
 852                                         $this->reportQueryError( $lastError, $lastErrno, $sql, $fname );
 853                                 } else {
 854                                         # Should be safe to silently retry the query
 855                                         $ret = $this->doProfiledQuery( $sql, $commentedSql, $isWrite, $fname );
 856                                 }
 857                         } else {
 858                                 $msg = __METHOD__ . ": lost connection to {$this->getServer()} permanently";
 859                                 $this->connLogger->error( $msg );
 860                         }
 861                 }
 862
 863                 if ( false === $ret ) {
 864                         # Deadlocks cause the entire transaction to abort, not just the statement.
 865                         # http://dev.mysql.com/doc/refman/5.7/en/innodb-error-handling.html
 866                         # https://www.postgresql.org/docs/9.1/static/explicit-locking.html
 867                         if ( $this->wasDeadlock() ) {
 868                                 if ( $this->explicitTrxActive() || $priorWritesPending ) {
 869                                         $tempIgnore = false; // not recoverable
 870                                 }
 871                                 # Update state tracking to reflect transaction loss
 872                                 $this->handleTransactionLoss();
 873                         }
 874
 875                         $this->reportQueryError(
 876                                 $this->lastError(), $this->lastErrno(), $sql, $fname, $tempIgnore );
 877                 }
 878
 879                 $res = $this->resultObject( $ret );
 880
 881                 return $res;
 882         }
 883
 884         private function doProfiledQuery( $sql, $commentedSql, $isWrite, $fname ) {
 885                 $isMaster = !is_null( $this->getLBInfo( 'master' ) );
 886                 # generalizeSQL() will probably cut down the query to reasonable
 887                 # logging size most of the time. The substr is really just a sanity check.
 888                 if ( $isMaster ) {
 889                         $queryProf = 'query-m: ' . substr( self::generalizeSQL( $sql ), 0, 255 );
 890                 } else {
 891                         $queryProf = 'query: ' . substr( self::generalizeSQL( $sql ), 0, 255 );
 892                 }
 893
 894                 # Include query transaction state
 895                 $queryProf .= $this->mTrxShortId ? " [TRX#{$this->mTrxShortId}]" : "";
 896
 897                 $startTime = microtime( true );
 898                 if ( $this->profiler ) {
 899                         call_user_func( [ $this->profiler, 'profileIn' ], $queryProf );
 900                 }
 901                 $ret = $this->doQuery( $commentedSql );
 902                 if ( $this->profiler ) {
 903                         call_user_func( [ $this->profiler, 'profileOut' ], $queryProf );
 904                 }
 905                 $queryRuntime = max( microtime( true ) - $startTime, 0.0 );
 906
 907                 unset( $queryProfSection ); // profile out (if set)
 908
 909                 if ( $ret !== false ) {
 910                         $this->lastPing = $startTime;
 911                         if ( $isWrite && $this->mTrxLevel ) {
 912                                 $this->updateTrxWriteQueryTime( $sql, $queryRuntime );
 913                                 $this->mTrxWriteCallers[] = $fname;
 914                         }
 915                 }
 916
 917                 if ( $sql === self::PING_QUERY ) {
 918                         $this->mRTTEstimate = $queryRuntime;
 919                 }
 920
 921                 $this->trxProfiler->recordQueryCompletion(
 922                         $queryProf, $startTime, $isWrite, $this->affectedRows()
 923                 );
 924                 $this->queryLogger->debug( $sql, [
 925                         'method' => $fname,
 926                         'master' => $isMaster,
 927                         'runtime' => $queryRuntime,
 928                 ] );
 929
 930                 return $ret;
 931         }
 932
 933         /**
 934          * Update the estimated run-time of a query, not counting large row lock times
 935          *
 936          * LoadBalancer can be set to rollback transactions that will create huge replication
 937          * lag. It bases this estimate off of pendingWriteQueryDuration(). Certain simple
 938          * queries, like inserting a row can take a long time due to row locking. This method
 939          * uses some simple heuristics to discount those cases.
 940          *
 941          * @param string $sql A SQL write query
 942          * @param float $runtime Total runtime, including RTT
 943          */
 944         private function updateTrxWriteQueryTime( $sql, $runtime ) {
 945                 // Whether this is indicative of replica DB runtime (except for RBR or ws_repl)
 946                 $indicativeOfReplicaRuntime = true;
 947                 if ( $runtime > self::SLOW_WRITE_SEC ) {
 948                         $verb = $this->getQueryVerb( $sql );
 949                         // insert(), upsert(), replace() are fast unless bulky in size or blocked on locks
 950                         if ( $verb === 'INSERT' ) {
 951                                 $indicativeOfReplicaRuntime = $this->affectedRows() > self::SMALL_WRITE_ROWS;
 952                         } elseif ( $verb === 'REPLACE' ) {
 953                                 $indicativeOfReplicaRuntime = $this->affectedRows() > self::SMALL_WRITE_ROWS / 2;
 954                         }
 955                 }
 956
 957                 $this->mTrxWriteDuration += $runtime;
 958                 $this->mTrxWriteQueryCount += 1;
 959                 if ( $indicativeOfReplicaRuntime ) {
 960                         $this->mTrxWriteAdjDuration += $runtime;
 961                         $this->mTrxWriteAdjQueryCount += 1;
 962                 }
 963         }
 964
 965         private function canRecoverFromDisconnect( $sql, $priorWritesPending ) {
 966                 # Transaction dropped; this can mean lost writes, or REPEATABLE-READ snapshots.
 967                 # Dropped connections also mean that named locks are automatically released.
 968                 # Only allow error suppression in autocommit mode or when the lost transaction
 969                 # didn't matter anyway (aside from DBO_TRX snapshot loss).
 970                 if ( $this->mNamedLocksHeld ) {
 971                         return false; // possible critical section violation
 972                 } elseif ( $sql === 'COMMIT' ) {
 973                         return !$priorWritesPending; // nothing written anyway? (T127428)
 974                 } elseif ( $sql === 'ROLLBACK' ) {
 975                         return true; // transaction lost...which is also what was requested :)
 976                 } elseif ( $this->explicitTrxActive() ) {
 977                         return false; // don't drop atomocity
 978                 } elseif ( $priorWritesPending ) {
 979                         return false; // prior writes lost from implicit transaction
 980                 }
 981
 982                 return true;
 983         }
 984
 985         private function handleTransactionLoss() {
 986                 $this->mTrxLevel = 0;
 987                 $this->mTrxIdleCallbacks = []; // bug 65263
 988                 $this->mTrxPreCommitCallbacks = []; // bug 65263
 989                 try {
 990                         // Handle callbacks in mTrxEndCallbacks
 991                         $this->runOnTransactionIdleCallbacks( self::TRIGGER_ROLLBACK );
 992                         $this->runTransactionListenerCallbacks( self::TRIGGER_ROLLBACK );
 993                         return null;
 994                 } catch ( Exception $e ) {
 995                         // Already logged; move on...
 996                         return $e;
 997                 }
 998         }
 999
1000         public function reportQueryError( $error, $errno, $sql, $fname, $tempIgnore = false ) {
1001                 if ( $this->ignoreErrors() || $tempIgnore ) {
1002                         $this->queryLogger->debug( "SQL ERROR (ignored): $error\n" );
1003                 } else {
1004                         $sql1line = mb_substr( str_replace( "\n", "\\n", $sql ), 0, 5 * 1024 );
1005                         $this->queryLogger->error(
1006                                 "{fname}\t{db_server}\t{errno}\t{error}\t{sql1line}",
1007                                 $this->getLogContext( [
1008                                         'method' => __METHOD__,
1009                                         'errno' => $errno,
1010                                         'error' => $error,
1011                                         'sql1line' => $sql1line,
1012                                         'fname' => $fname,
1013                                 ] )
1014                         );
1015                         $this->queryLogger->debug( "SQL ERROR: " . $error . "\n" );
1016                         throw new DBQueryError( $this, $error, $errno, $sql, $fname );
1017                 }
1018         }
1019
1020         public function freeResult( $res ) {
1021         }
1022
1023         public function selectField(
1024                 $table, $var, $cond = '', $fname = __METHOD__, $options = []
1025         ) {
1026                 if ( $var === '*' ) { // sanity
1027                         throw new DBUnexpectedError( $this, "Cannot use a * field: got '$var'" );
1028                 }
1029
1030                 if ( !is_array( $options ) ) {
1031                         $options = [ $options ];
1032                 }
1033
1034                 $options['LIMIT'] = 1;
1035
1036                 $res = $this->select( $table, $var, $cond, $fname, $options );
1037                 if ( $res === false || !$this->numRows( $res ) ) {
1038                         return false;
1039                 }
1040
1041                 $row = $this->fetchRow( $res );
1042
1043                 if ( $row !== false ) {
1044                         return reset( $row );
1045                 } else {
1046                         return false;
1047                 }
1048         }
1049
1050         public function selectFieldValues(
1051                 $table, $var, $cond = '', $fname = __METHOD__, $options = [], $join_conds = []
1052         ) {
1053                 if ( $var === '*' ) { // sanity
1054                         throw new DBUnexpectedError( $this, "Cannot use a * field" );
1055                 } elseif ( !is_string( $var ) ) { // sanity
1056                         throw new DBUnexpectedError( $this, "Cannot use an array of fields" );
1057                 }
1058
1059                 if ( !is_array( $options ) ) {
1060                         $options = [ $options ];
1061                 }
1062
1063                 $res = $this->select( $table, $var, $cond, $fname, $options, $join_conds );
1064                 if ( $res === false ) {
1065                         return false;
1066                 }
1067
1068                 $values = [];
1069                 foreach ( $res as $row ) {
1070                         $values[] = $row->$var;
1071                 }
1072
1073                 return $values;
1074         }
1075
1076         /**
1077          * Returns an optional USE INDEX clause to go after the table, and a
1078          * string to go at the end of the query.
1079          *
1080          * @param array $options Associative array of options to be turned into
1081          *   an SQL query, valid keys are listed in the function.
1082          * @return array
1083          * @see DatabaseBase::select()
1084          */
1085         public function makeSelectOptions( $options ) {
1086                 $preLimitTail = $postLimitTail = '';
1087                 $startOpts = '';
1088
1089                 $noKeyOptions = [];
1090
1091                 foreach ( $options as $key => $option ) {
1092                         if ( is_numeric( $key ) ) {
1093                                 $noKeyOptions[$option] = true;
1094                         }
1095                 }
1096
1097                 $preLimitTail .= $this->makeGroupByWithHaving( $options );
1098
1099                 $preLimitTail .= $this->makeOrderBy( $options );
1100
1101                 // if (isset($options['LIMIT'])) {
1102                 //      $tailOpts .= $this->limitResult('', $options['LIMIT'],
1103                 //              isset($options['OFFSET']) ? $options['OFFSET']
1104                 //              : false);
1105                 // }
1106
1107                 if ( isset( $noKeyOptions['FOR UPDATE'] ) ) {
1108                         $postLimitTail .= ' FOR UPDATE';
1109                 }
1110
1111                 if ( isset( $noKeyOptions['LOCK IN SHARE MODE'] ) ) {
1112                         $postLimitTail .= ' LOCK IN SHARE MODE';
1113                 }
1114
1115                 if ( isset( $noKeyOptions['DISTINCT'] ) || isset( $noKeyOptions['DISTINCTROW'] ) ) {
1116                         $startOpts .= 'DISTINCT';
1117                 }
1118
1119                 # Various MySQL extensions
1120                 if ( isset( $noKeyOptions['STRAIGHT_JOIN'] ) ) {
1121                         $startOpts .= ' /*! STRAIGHT_JOIN */';
1122                 }
1123
1124                 if ( isset( $noKeyOptions['HIGH_PRIORITY'] ) ) {
1125                         $startOpts .= ' HIGH_PRIORITY';
1126                 }
1127
1128                 if ( isset( $noKeyOptions['SQL_BIG_RESULT'] ) ) {
1129                         $startOpts .= ' SQL_BIG_RESULT';
1130                 }
1131
1132                 if ( isset( $noKeyOptions['SQL_BUFFER_RESULT'] ) ) {
1133                         $startOpts .= ' SQL_BUFFER_RESULT';
1134                 }
1135
1136                 if ( isset( $noKeyOptions['SQL_SMALL_RESULT'] ) ) {
1137                         $startOpts .= ' SQL_SMALL_RESULT';
1138                 }
1139
1140                 if ( isset( $noKeyOptions['SQL_CALC_FOUND_ROWS'] ) ) {
1141                         $startOpts .= ' SQL_CALC_FOUND_ROWS';
1142                 }
1143
1144                 if ( isset( $noKeyOptions['SQL_CACHE'] ) ) {
1145                         $startOpts .= ' SQL_CACHE';
1146                 }
1147
1148                 if ( isset( $noKeyOptions['SQL_NO_CACHE'] ) ) {
1149                         $startOpts .= ' SQL_NO_CACHE';
1150                 }
1151
1152                 if ( isset( $options['USE INDEX'] ) && is_string( $options['USE INDEX'] ) ) {
1153                         $useIndex = $this->useIndexClause( $options['USE INDEX'] );
1154                 } else {
1155                         $useIndex = '';
1156                 }
1157                 if ( isset( $options['IGNORE INDEX'] ) && is_string( $options['IGNORE INDEX'] ) ) {
1158                         $ignoreIndex = $this->ignoreIndexClause( $options['IGNORE INDEX'] );
1159                 } else {
1160                         $ignoreIndex = '';
1161                 }
1162
1163                 return [ $startOpts, $useIndex, $preLimitTail, $postLimitTail, $ignoreIndex ];
1164         }
1165
1166         /**
1167          * Returns an optional GROUP BY with an optional HAVING
1168          *
1169          * @param array $options Associative array of options
1170          * @return string
1171          * @see DatabaseBase::select()
1172          * @since 1.21
1173          */
1174         public function makeGroupByWithHaving( $options ) {
1175                 $sql = '';
1176                 if ( isset( $options['GROUP BY'] ) ) {
1177                         $gb = is_array( $options['GROUP BY'] )
1178                                 ? implode( ',', $options['GROUP BY'] )
1179                                 : $options['GROUP BY'];
1180                         $sql .= ' GROUP BY ' . $gb;
1181                 }
1182                 if ( isset( $options['HAVING'] ) ) {
1183                         $having = is_array( $options['HAVING'] )
1184                                 ? $this->makeList( $options['HAVING'], self::LIST_AND )
1185                                 : $options['HAVING'];
1186                         $sql .= ' HAVING ' . $having;
1187                 }
1188
1189                 return $sql;
1190         }
1191
1192         /**
1193          * Returns an optional ORDER BY
1194          *
1195          * @param array $options Associative array of options
1196          * @return string
1197          * @see DatabaseBase::select()
1198          * @since 1.21
1199          */
1200         public function makeOrderBy( $options ) {
1201                 if ( isset( $options['ORDER BY'] ) ) {
1202                         $ob = is_array( $options['ORDER BY'] )
1203                                 ? implode( ',', $options['ORDER BY'] )
1204                                 : $options['ORDER BY'];
1205
1206                         return ' ORDER BY ' . $ob;
1207                 }
1208
1209                 return '';
1210         }
1211
1212         // See IDatabase::select for the docs for this function
1213         public function select( $table, $vars, $conds = '', $fname = __METHOD__,
1214                 $options = [], $join_conds = [] ) {
1215                 $sql = $this->selectSQLText( $table, $vars, $conds, $fname, $options, $join_conds );
1216
1217                 return $this->query( $sql, $fname );
1218         }
1219
1220         public function selectSQLText( $table, $vars, $conds = '', $fname = __METHOD__,
1221                 $options = [], $join_conds = []
1222         ) {
1223                 if ( is_array( $vars ) ) {
1224                         $vars = implode( ',', $this->fieldNamesWithAlias( $vars ) );
1225                 }
1226
1227                 $options = (array)$options;
1228                 $useIndexes = ( isset( $options['USE INDEX'] ) && is_array( $options['USE INDEX'] ) )
1229                         ? $options['USE INDEX']
1230                         : [];
1231                 $ignoreIndexes = ( isset( $options['IGNORE INDEX'] ) && is_array( $options['IGNORE INDEX'] ) )
1232                         ? $options['IGNORE INDEX']
1233                         : [];
1234
1235                 if ( is_array( $table ) ) {
1236                         $from = ' FROM ' .
1237                                 $this->tableNamesWithIndexClauseOrJOIN( $table, $useIndexes, $ignoreIndexes, $join_conds );
1238                 } elseif ( $table != '' ) {
1239                         if ( $table[0] == ' ' ) {
1240                                 $from = ' FROM ' . $table;
1241                         } else {
1242                                 $from = ' FROM ' .
1243                                         $this->tableNamesWithIndexClauseOrJOIN( [ $table ], $useIndexes, $ignoreIndexes, [] );
1244                         }
1245                 } else {
1246                         $from = '';
1247                 }
1248
1249                 list( $startOpts, $useIndex, $preLimitTail, $postLimitTail, $ignoreIndex ) =
1250                         $this->makeSelectOptions( $options );
1251
1252                 if ( !empty( $conds ) ) {
1253                         if ( is_array( $conds ) ) {
1254                                 $conds = $this->makeList( $conds, self::LIST_AND );
1255                         }
1256                         $sql = "SELECT $startOpts $vars $from $useIndex $ignoreIndex WHERE $conds $preLimitTail";
1257                 } else {
1258                         $sql = "SELECT $startOpts $vars $from $useIndex $ignoreIndex $preLimitTail";
1259                 }
1260
1261                 if ( isset( $options['LIMIT'] ) ) {
1262                         $sql = $this->limitResult( $sql, $options['LIMIT'],
1263                                 isset( $options['OFFSET'] ) ? $options['OFFSET'] : false );
1264                 }
1265                 $sql = "$sql $postLimitTail";
1266
1267                 if ( isset( $options['EXPLAIN'] ) ) {
1268                         $sql = 'EXPLAIN ' . $sql;
1269                 }
1270
1271                 return $sql;
1272         }
1273
1274         public function selectRow( $table, $vars, $conds, $fname = __METHOD__,
1275                 $options = [], $join_conds = []
1276         ) {
1277                 $options = (array)$options;
1278                 $options['LIMIT'] = 1;
1279                 $res = $this->select( $table, $vars, $conds, $fname, $options, $join_conds );
1280
1281                 if ( $res === false ) {
1282                         return false;
1283                 }
1284
1285                 if ( !$this->numRows( $res ) ) {
1286                         return false;
1287                 }
1288
1289                 $obj = $this->fetchObject( $res );
1290
1291                 return $obj;
1292         }
1293
1294         public function estimateRowCount(
1295                 $table, $vars = '*', $conds = '', $fname = __METHOD__, $options = []
1296         ) {
1297                 $rows = 0;
1298                 $res = $this->select( $table, [ 'rowcount' => 'COUNT(*)' ], $conds, $fname, $options );
1299
1300                 if ( $res ) {
1301                         $row = $this->fetchRow( $res );
1302                         $rows = ( isset( $row['rowcount'] ) ) ? (int)$row['rowcount'] : 0;
1303                 }
1304
1305                 return $rows;
1306         }
1307
1308         public function selectRowCount(
1309                 $tables, $vars = '*', $conds = '', $fname = __METHOD__, $options = [], $join_conds = []
1310         ) {
1311                 $rows = 0;
1312                 $sql = $this->selectSQLText( $tables, '1', $conds, $fname, $options, $join_conds );
1313                 $res = $this->query( "SELECT COUNT(*) AS rowcount FROM ($sql) tmp_count", $fname );
1314
1315                 if ( $res ) {
1316                         $row = $this->fetchRow( $res );
1317                         $rows = ( isset( $row['rowcount'] ) ) ? (int)$row['rowcount'] : 0;
1318                 }
1319
1320                 return $rows;
1321         }
1322
1323         /**
1324          * Removes most variables from an SQL query and replaces them with X or N for numbers.
1325          * It's only slightly flawed. Don't use for anything important.
1326          *
1327          * @param string $sql A SQL Query
1328          *
1329          * @return string
1330          */
1331         protected static function generalizeSQL( $sql ) {
1332                 # This does the same as the regexp below would do, but in such a way
1333                 # as to avoid crashing php on some large strings.
1334                 # $sql = preg_replace( "/'([^\\\\']|\\\\.)*'|\"([^\\\\\"]|\\\\.)*\"/", "'X'", $sql );
1335
1336                 $sql = str_replace( "\\\\", '', $sql );
1337                 $sql = str_replace( "\\'", '', $sql );
1338                 $sql = str_replace( "\\\"", '', $sql );
1339                 $sql = preg_replace( "/'.*'/s", "'X'", $sql );
1340                 $sql = preg_replace( '/".*"/s', "'X'", $sql );
1341
1342                 # All newlines, tabs, etc replaced by single space
1343                 $sql = preg_replace( '/\s+/', ' ', $sql );
1344
1345                 # All numbers => N,
1346                 # except the ones surrounded by characters, e.g. l10n
1347                 $sql = preg_replace( '/-?\d+(,-?\d+)+/s', 'N,...,N', $sql );
1348                 $sql = preg_replace( '/(?<![a-zA-Z])-?\d+(?![a-zA-Z])/s', 'N', $sql );
1349
1350                 return $sql;
1351         }
1352
1353         public function fieldExists( $table, $field, $fname = __METHOD__ ) {
1354                 $info = $this->fieldInfo( $table, $field );
1355
1356                 return (bool)$info;
1357         }
1358
1359         public function indexExists( $table, $index, $fname = __METHOD__ ) {
1360                 if ( !$this->tableExists( $table ) ) {
1361                         return null;
1362                 }
1363
1364                 $info = $this->indexInfo( $table, $index, $fname );
1365                 if ( is_null( $info ) ) {
1366                         return null;
1367                 } else {
1368                         return $info !== false;
1369                 }
1370         }
1371
1372         public function tableExists( $table, $fname = __METHOD__ ) {
1373                 $table = $this->tableName( $table );
1374                 $old = $this->ignoreErrors( true );
1375                 $res = $this->query( "SELECT 1 FROM $table LIMIT 1", $fname );
1376                 $this->ignoreErrors( $old );
1377
1378                 return (bool)$res;
1379         }
1380
1381         public function indexUnique( $table, $index ) {
1382                 $indexInfo = $this->indexInfo( $table, $index );
1383
1384                 if ( !$indexInfo ) {
1385                         return null;
1386                 }
1387
1388                 return !$indexInfo[0]->Non_unique;
1389         }
1390
1391         /**
1392          * Helper for DatabaseBase::insert().
1393          *
1394          * @param array $options
1395          * @return string
1396          */
1397         protected function makeInsertOptions( $options ) {
1398                 return implode( ' ', $options );
1399         }
1400
1401         public function insert( $table, $a, $fname = __METHOD__, $options = [] ) {
1402                 # No rows to insert, easy just return now
1403                 if ( !count( $a ) ) {
1404                         return true;
1405                 }
1406
1407                 $table = $this->tableName( $table );
1408
1409                 if ( !is_array( $options ) ) {
1410                         $options = [ $options ];
1411                 }
1412
1413                 $fh = null;
1414                 if ( isset( $options['fileHandle'] ) ) {
1415                         $fh = $options['fileHandle'];
1416                 }
1417                 $options = $this->makeInsertOptions( $options );
1418
1419                 if ( isset( $a[0] ) && is_array( $a[0] ) ) {
1420                         $multi = true;
1421                         $keys = array_keys( $a[0] );
1422                 } else {
1423                         $multi = false;
1424                         $keys = array_keys( $a );
1425                 }
1426
1427                 $sql = 'INSERT ' . $options .
1428                         " INTO $table (" . implode( ',', $keys ) . ') VALUES ';
1429
1430                 if ( $multi ) {
1431                         $first = true;
1432                         foreach ( $a as $row ) {
1433                                 if ( $first ) {
1434                                         $first = false;
1435                                 } else {
1436                                         $sql .= ',';
1437                                 }
1438                                 $sql .= '(' . $this->makeList( $row ) . ')';
1439                         }
1440                 } else {
1441                         $sql .= '(' . $this->makeList( $a ) . ')';
1442                 }
1443
1444                 if ( $fh !== null && false === fwrite( $fh, $sql ) ) {
1445                         return false;
1446                 } elseif ( $fh !== null ) {
1447                         return true;
1448                 }
1449
1450                 return (bool)$this->query( $sql, $fname );
1451         }
1452
1453         /**
1454          * Make UPDATE options array for DatabaseBase::makeUpdateOptions
1455          *
1456          * @param array $options
1457          * @return array
1458          */
1459         protected function makeUpdateOptionsArray( $options ) {
1460                 if ( !is_array( $options ) ) {
1461                         $options = [ $options ];
1462                 }
1463
1464                 $opts = [];
1465
1466                 if ( in_array( 'IGNORE', $options ) ) {
1467                         $opts[] = 'IGNORE';
1468                 }
1469
1470                 return $opts;
1471         }
1472
1473         /**
1474          * Make UPDATE options for the DatabaseBase::update function
1475          *
1476          * @param array $options The options passed to DatabaseBase::update
1477          * @return string
1478          */
1479         protected function makeUpdateOptions( $options ) {
1480                 $opts = $this->makeUpdateOptionsArray( $options );
1481
1482                 return implode( ' ', $opts );
1483         }
1484
1485         function update( $table, $values, $conds, $fname = __METHOD__, $options = [] ) {
1486                 $table = $this->tableName( $table );
1487                 $opts = $this->makeUpdateOptions( $options );
1488                 $sql = "UPDATE $opts $table SET " . $this->makeList( $values, self::LIST_SET );
1489
1490                 if ( $conds !== [] && $conds !== '*' ) {
1491                         $sql .= " WHERE " . $this->makeList( $conds, self::LIST_AND );
1492                 }
1493
1494                 return $this->query( $sql, $fname );
1495         }
1496
1497         public function makeList( $a, $mode = self::LIST_COMMA ) {
1498                 if ( !is_array( $a ) ) {
1499                         throw new DBUnexpectedError( $this, __METHOD__ . ' called with incorrect parameters' );
1500                 }
1501
1502                 $first = true;
1503                 $list = '';
1504
1505                 foreach ( $a as $field => $value ) {
1506                         if ( !$first ) {
1507                                 if ( $mode == self::LIST_AND ) {
1508                                         $list .= ' AND ';
1509                                 } elseif ( $mode == self::LIST_OR ) {
1510                                         $list .= ' OR ';
1511                                 } else {
1512                                         $list .= ',';
1513                                 }
1514                         } else {
1515                                 $first = false;
1516                         }
1517
1518                         if ( ( $mode == self::LIST_AND || $mode == self::LIST_OR ) && is_numeric( $field ) ) {
1519                                 $list .= "($value)";
1520                         } elseif ( $mode == self::LIST_SET && is_numeric( $field ) ) {
1521                                 $list .= "$value";
1522                         } elseif (
1523                                 ( $mode == self::LIST_AND || $mode == self::LIST_OR ) && is_array( $value )
1524                         ) {
1525                                 // Remove null from array to be handled separately if found
1526                                 $includeNull = false;
1527                                 foreach ( array_keys( $value, null, true ) as $nullKey ) {
1528                                         $includeNull = true;
1529                                         unset( $value[$nullKey] );
1530                                 }
1531                                 if ( count( $value ) == 0 && !$includeNull ) {
1532                                         throw new InvalidArgumentException(
1533                                                 __METHOD__ . ": empty input for field $field" );
1534                                 } elseif ( count( $value ) == 0 ) {
1535                                         // only check if $field is null
1536                                         $list .= "$field IS NULL";
1537                                 } else {
1538                                         // IN clause contains at least one valid element
1539                                         if ( $includeNull ) {
1540                                                 // Group subconditions to ensure correct precedence
1541                                                 $list .= '(';
1542                                         }
1543                                         if ( count( $value ) == 1 ) {
1544                                                 // Special-case single values, as IN isn't terribly efficient
1545                                                 // Don't necessarily assume the single key is 0; we don't
1546                                                 // enforce linear numeric ordering on other arrays here.
1547                                                 $value = array_values( $value )[0];
1548                                                 $list .= $field . " = " . $this->addQuotes( $value );
1549                                         } else {
1550                                                 $list .= $field . " IN (" . $this->makeList( $value ) . ") ";
1551                                         }
1552                                         // if null present in array, append IS NULL
1553                                         if ( $includeNull ) {
1554                                                 $list .= " OR $field IS NULL)";
1555                                         }
1556                                 }
1557                         } elseif ( $value === null ) {
1558                                 if ( $mode == self::LIST_AND || $mode == self::LIST_OR ) {
1559                                         $list .= "$field IS ";
1560                                 } elseif ( $mode == self::LIST_SET ) {
1561                                         $list .= "$field = ";
1562                                 }
1563                                 $list .= 'NULL';
1564                         } else {
1565                                 if (
1566                                         $mode == self::LIST_AND || $mode == self::LIST_OR || $mode == self::LIST_SET
1567                                 ) {
1568                                         $list .= "$field = ";
1569                                 }
1570                                 $list .= $mode == self::LIST_NAMES ? $value : $this->addQuotes( $value );
1571                         }
1572                 }
1573
1574                 return $list;
1575         }
1576
1577         public function makeWhereFrom2d( $data, $baseKey, $subKey ) {
1578                 $conds = [];
1579
1580                 foreach ( $data as $base => $sub ) {
1581                         if ( count( $sub ) ) {
1582                                 $conds[] = $this->makeList(
1583                                         [ $baseKey => $base, $subKey => array_keys( $sub ) ],
1584                                         self::LIST_AND );
1585                         }
1586                 }
1587
1588                 if ( $conds ) {
1589                         return $this->makeList( $conds, self::LIST_OR );
1590                 } else {
1591                         // Nothing to search for...
1592                         return false;
1593                 }
1594         }
1595
1596         /**
1597          * Return aggregated value alias
1598          *
1599          * @param array $valuedata
1600          * @param string $valuename
1601          *
1602          * @return string
1603          */
1604         public function aggregateValue( $valuedata, $valuename = 'value' ) {
1605                 return $valuename;
1606         }
1607
1608         public function bitNot( $field ) {
1609                 return "(~$field)";
1610         }
1611
1612         public function bitAnd( $fieldLeft, $fieldRight ) {
1613                 return "($fieldLeft & $fieldRight)";
1614         }
1615
1616         public function bitOr( $fieldLeft, $fieldRight ) {
1617                 return "($fieldLeft | $fieldRight)";
1618         }
1619
1620         public function buildConcat( $stringList ) {
1621                 return 'CONCAT(' . implode( ',', $stringList ) . ')';
1622         }
1623
1624         public function buildGroupConcatField(
1625                 $delim, $table, $field, $conds = '', $join_conds = []
1626         ) {
1627                 $fld = "GROUP_CONCAT($field SEPARATOR " . $this->addQuotes( $delim ) . ')';
1628
1629                 return '(' . $this->selectSQLText( $table, $fld, $conds, null, [], $join_conds ) . ')';
1630         }
1631
1632         /**
1633          * @param string $field Field or column to cast
1634          * @return string
1635          * @since 1.28
1636          */
1637         public function buildStringCast( $field ) {
1638                 return $field;
1639         }
1640
1641         public function selectDB( $db ) {
1642                 # Stub. Shouldn't cause serious problems if it's not overridden, but
1643                 # if your database engine supports a concept similar to MySQL's
1644                 # databases you may as well.
1645                 $this->mDBname = $db;
1646
1647                 return true;
1648         }
1649
1650         public function getDBname() {
1651                 return $this->mDBname;
1652         }
1653
1654         public function getServer() {
1655                 return $this->mServer;
1656         }
1657
1658         /**
1659          * Format a table name ready for use in constructing an SQL query
1660          *
1661          * This does two important things: it quotes the table names to clean them up,
1662          * and it adds a table prefix if only given a table name with no quotes.
1663          *
1664          * All functions of this object which require a table name call this function
1665          * themselves. Pass the canonical name to such functions. This is only needed
1666          * when calling query() directly.
1667          *
1668          * @note This function does not sanitize user input. It is not safe to use
1669          *   this function to escape user input.
1670          * @param string $name Database table name
1671          * @param string $format One of:
1672          *   quoted - Automatically pass the table name through addIdentifierQuotes()
1673          *            so that it can be used in a query.
1674          *   raw - Do not add identifier quotes to the table name
1675          * @return string Full database name
1676          */
1677         public function tableName( $name, $format = 'quoted' ) {
1678                 # Skip the entire process when we have a string quoted on both ends.
1679                 # Note that we check the end so that we will still quote any use of
1680                 # use of `database`.table. But won't break things if someone wants
1681                 # to query a database table with a dot in the name.
1682                 if ( $this->isQuotedIdentifier( $name ) ) {
1683                         return $name;
1684                 }
1685
1686                 # Lets test for any bits of text that should never show up in a table
1687                 # name. Basically anything like JOIN or ON which are actually part of
1688                 # SQL queries, but may end up inside of the table value to combine
1689                 # sql. Such as how the API is doing.
1690                 # Note that we use a whitespace test rather than a \b test to avoid
1691                 # any remote case where a word like on may be inside of a table name
1692                 # surrounded by symbols which may be considered word breaks.
1693                 if ( preg_match( '/(^|\s)(DISTINCT|JOIN|ON|AS)(\s|$)/i', $name ) !== 0 ) {
1694                         return $name;
1695                 }
1696
1697                 # Split database and table into proper variables.
1698                 # We reverse the explode so that database.table and table both output
1699                 # the correct table.
1700                 $dbDetails = explode( '.', $name, 3 );
1701                 if ( count( $dbDetails ) == 3 ) {
1702                         list( $database, $schema, $table ) = $dbDetails;
1703                         # We don't want any prefix added in this case
1704                         $prefix = '';
1705                 } elseif ( count( $dbDetails ) == 2 ) {
1706                         list( $database, $table ) = $dbDetails;
1707                         # We don't want any prefix added in this case
1708                         # In dbs that support it, $database may actually be the schema
1709                         # but that doesn't affect any of the functionality here
1710                         $prefix = '';
1711                         $schema = '';
1712                 } else {
1713                         list( $table ) = $dbDetails;
1714                         if ( isset( $this->tableAliases[$table] ) ) {
1715                                 $database = $this->tableAliases[$table]['dbname'];
1716                                 $schema = is_string( $this->tableAliases[$table]['schema'] )
1717                                         ? $this->tableAliases[$table]['schema']
1718                                         : $this->mSchema;
1719                                 $prefix = is_string( $this->tableAliases[$table]['prefix'] )
1720                                         ? $this->tableAliases[$table]['prefix']
1721                                         : $this->mTablePrefix;
1722                         } else {
1723                                 $database = '';
1724                                 $schema = $this->mSchema; # Default schema
1725                                 $prefix = $this->mTablePrefix; # Default prefix
1726                         }
1727                 }
1728
1729                 # Quote $table and apply the prefix if not quoted.
1730                 # $tableName might be empty if this is called from Database::replaceVars()
1731                 $tableName = "{$prefix}{$table}";
1732                 if ( $format == 'quoted'
1733                         && !$this->isQuotedIdentifier( $tableName ) && $tableName !== ''
1734                 ) {
1735                         $tableName = $this->addIdentifierQuotes( $tableName );
1736                 }
1737
1738                 # Quote $schema and merge it with the table name if needed
1739                 if ( strlen( $schema ) ) {
1740                         if ( $format == 'quoted' && !$this->isQuotedIdentifier( $schema ) ) {
1741                                 $schema = $this->addIdentifierQuotes( $schema );
1742                         }
1743                         $tableName = $schema . '.' . $tableName;
1744                 }
1745
1746                 # Quote $database and merge it with the table name if needed
1747                 if ( $database !== '' ) {
1748                         if ( $format == 'quoted' && !$this->isQuotedIdentifier( $database ) ) {
1749                                 $database = $this->addIdentifierQuotes( $database );
1750                         }
1751                         $tableName = $database . '.' . $tableName;
1752                 }
1753
1754                 return $tableName;
1755         }
1756
1757         /**
1758          * Fetch a number of table names into an array
1759          * This is handy when you need to construct SQL for joins
1760          *
1761          * Example:
1762          * extract( $dbr->tableNames( 'user', 'watchlist' ) );
1763          * $sql = "SELECT wl_namespace,wl_title FROM $watchlist,$user
1764          *         WHERE wl_user=user_id AND wl_user=$nameWithQuotes";
1765          *
1766          * @return array
1767          */
1768         public function tableNames() {
1769                 $inArray = func_get_args();
1770                 $retVal = [];
1771
1772                 foreach ( $inArray as $name ) {
1773                         $retVal[$name] = $this->tableName( $name );
1774                 }
1775
1776                 return $retVal;
1777         }
1778
1779         /**
1780          * Fetch a number of table names into an zero-indexed numerical array
1781          * This is handy when you need to construct SQL for joins
1782          *
1783          * Example:
1784          * list( $user, $watchlist ) = $dbr->tableNamesN( 'user', 'watchlist' );
1785          * $sql = "SELECT wl_namespace,wl_title FROM $watchlist,$user
1786          *         WHERE wl_user=user_id AND wl_user=$nameWithQuotes";
1787          *
1788          * @return array
1789          */
1790         public function tableNamesN() {
1791                 $inArray = func_get_args();
1792                 $retVal = [];
1793
1794                 foreach ( $inArray as $name ) {
1795                         $retVal[] = $this->tableName( $name );
1796                 }
1797
1798                 return $retVal;
1799         }
1800
1801         /**
1802          * Get an aliased table name
1803          * e.g. tableName AS newTableName
1804          *
1805          * @param string $name Table name, see tableName()
1806          * @param string|bool $alias Alias (optional)
1807          * @return string SQL name for aliased table. Will not alias a table to its own name
1808          */
1809         public function tableNameWithAlias( $name, $alias = false ) {
1810                 if ( !$alias || $alias == $name ) {
1811                         return $this->tableName( $name );
1812                 } else {
1813                         return $this->tableName( $name ) . ' ' . $this->addIdentifierQuotes( $alias );
1814                 }
1815         }
1816
1817         /**
1818          * Gets an array of aliased table names
1819          *
1820          * @param array $tables [ [alias] => table ]
1821          * @return string[] See tableNameWithAlias()
1822          */
1823         public function tableNamesWithAlias( $tables ) {
1824                 $retval = [];
1825                 foreach ( $tables as $alias => $table ) {
1826                         if ( is_numeric( $alias ) ) {
1827                                 $alias = $table;
1828                         }
1829                         $retval[] = $this->tableNameWithAlias( $table, $alias );
1830                 }
1831
1832                 return $retval;
1833         }
1834
1835         /**
1836          * Get an aliased field name
1837          * e.g. fieldName AS newFieldName
1838          *
1839          * @param string $name Field name
1840          * @param string|bool $alias Alias (optional)
1841          * @return string SQL name for aliased field. Will not alias a field to its own name
1842          */
1843         public function fieldNameWithAlias( $name, $alias = false ) {
1844                 if ( !$alias || (string)$alias === (string)$name ) {
1845                         return $name;
1846                 } else {
1847                         return $name . ' AS ' . $this->addIdentifierQuotes( $alias ); // PostgreSQL needs AS
1848                 }
1849         }
1850
1851         /**
1852          * Gets an array of aliased field names
1853          *
1854          * @param array $fields [ [alias] => field ]
1855          * @return string[] See fieldNameWithAlias()
1856          */
1857         public function fieldNamesWithAlias( $fields ) {
1858                 $retval = [];
1859                 foreach ( $fields as $alias => $field ) {
1860                         if ( is_numeric( $alias ) ) {
1861                                 $alias = $field;
1862                         }
1863                         $retval[] = $this->fieldNameWithAlias( $field, $alias );
1864                 }
1865
1866                 return $retval;
1867         }
1868
1869         /**
1870          * Get the aliased table name clause for a FROM clause
1871          * which might have a JOIN and/or USE INDEX or IGNORE INDEX clause
1872          *
1873          * @param array $tables ( [alias] => table )
1874          * @param array $use_index Same as for select()
1875          * @param array $ignore_index Same as for select()
1876          * @param array $join_conds Same as for select()
1877          * @return string
1878          */
1879         protected function tableNamesWithIndexClauseOrJOIN(
1880                 $tables, $use_index = [], $ignore_index = [], $join_conds = []
1881         ) {
1882                 $ret = [];
1883                 $retJOIN = [];
1884                 $use_index = (array)$use_index;
1885                 $ignore_index = (array)$ignore_index;
1886                 $join_conds = (array)$join_conds;
1887
1888                 foreach ( $tables as $alias => $table ) {
1889                         if ( !is_string( $alias ) ) {
1890                                 // No alias? Set it equal to the table name
1891                                 $alias = $table;
1892                         }
1893                         // Is there a JOIN clause for this table?
1894                         if ( isset( $join_conds[$alias] ) ) {
1895                                 list( $joinType, $conds ) = $join_conds[$alias];
1896                                 $tableClause = $joinType;
1897                                 $tableClause .= ' ' . $this->tableNameWithAlias( $table, $alias );
1898                                 if ( isset( $use_index[$alias] ) ) { // has USE INDEX?
1899                                         $use = $this->useIndexClause( implode( ',', (array)$use_index[$alias] ) );
1900                                         if ( $use != '' ) {
1901                                                 $tableClause .= ' ' . $use;
1902                                         }
1903                                 }
1904                                 if ( isset( $ignore_index[$alias] ) ) { // has IGNORE INDEX?
1905                                         $ignore = $this->ignoreIndexClause( implode( ',', (array)$ignore_index[$alias] ) );
1906                                         if ( $ignore != '' ) {
1907                                                 $tableClause .= ' ' . $ignore;
1908                                         }
1909                                 }
1910                                 $on = $this->makeList( (array)$conds, self::LIST_AND );
1911                                 if ( $on != '' ) {
1912                                         $tableClause .= ' ON (' . $on . ')';
1913                                 }
1914
1915                                 $retJOIN[] = $tableClause;
1916                         } elseif ( isset( $use_index[$alias] ) ) {
1917                                 // Is there an INDEX clause for this table?
1918                                 $tableClause = $this->tableNameWithAlias( $table, $alias );
1919                                 $tableClause .= ' ' . $this->useIndexClause(
1920                                                 implode( ',', (array)$use_index[$alias] )
1921                                         );
1922
1923                                 $ret[] = $tableClause;
1924                         } elseif ( isset( $ignore_index[$alias] ) ) {
1925                                 // Is there an INDEX clause for this table?
1926                                 $tableClause = $this->tableNameWithAlias( $table, $alias );
1927                                 $tableClause .= ' ' . $this->ignoreIndexClause(
1928                                                 implode( ',', (array)$ignore_index[$alias] )
1929                                         );
1930
1931                                 $ret[] = $tableClause;
1932                         } else {
1933                                 $tableClause = $this->tableNameWithAlias( $table, $alias );
1934
1935                                 $ret[] = $tableClause;
1936                         }
1937                 }
1938
1939                 // We can't separate explicit JOIN clauses with ',', use ' ' for those
1940                 $implicitJoins = !empty( $ret ) ? implode( ',', $ret ) : "";
1941                 $explicitJoins = !empty( $retJOIN ) ? implode( ' ', $retJOIN ) : "";
1942
1943                 // Compile our final table clause
1944                 return implode( ' ', [ $implicitJoins, $explicitJoins ] );
1945         }
1946
1947         /**
1948          * Get the name of an index in a given table.
1949          *
1950          * @param string $index
1951          * @return string
1952          */
1953         protected function indexName( $index ) {
1954                 // Backwards-compatibility hack
1955                 $renamed = [
1956                         'ar_usertext_timestamp' => 'usertext_timestamp',
1957                         'un_user_id' => 'user_id',
1958                         'un_user_ip' => 'user_ip',
1959                 ];
1960
1961                 if ( isset( $renamed[$index] ) ) {
1962                         return $renamed[$index];
1963                 } else {
1964                         return $index;
1965                 }
1966         }
1967
1968         public function addQuotes( $s ) {
1969                 if ( $s instanceof Blob ) {
1970                         $s = $s->fetch();
1971                 }
1972                 if ( $s === null ) {
1973                         return 'NULL';
1974                 } else {
1975                         # This will also quote numeric values. This should be harmless,
1976                         # and protects against weird problems that occur when they really
1977                         # _are_ strings such as article titles and string->number->string
1978                         # conversion is not 1:1.
1979                         return "'" . $this->strencode( $s ) . "'";
1980                 }
1981         }
1982
1983         /**
1984          * Quotes an identifier using `backticks` or "double quotes" depending on the database type.
1985          * MySQL uses `backticks` while basically everything else uses double quotes.
1986          * Since MySQL is the odd one out here the double quotes are our generic
1987          * and we implement backticks in DatabaseMysql.
1988          *
1989          * @param string $s
1990          * @return string
1991          */
1992         public function addIdentifierQuotes( $s ) {
1993                 return '"' . str_replace( '"', '""', $s ) . '"';
1994         }
1995
1996         /**
1997          * Returns if the given identifier looks quoted or not according to
1998          * the database convention for quoting identifiers .
1999          *
2000          * @note Do not use this to determine if untrusted input is safe.
2001          *   A malicious user can trick this function.
2002          * @param string $name
2003          * @return bool
2004          */
2005         public function isQuotedIdentifier( $name ) {
2006                 return $name[0] == '"' && substr( $name, -1, 1 ) == '"';
2007         }
2008
2009         /**
2010          * @param string $s
2011          * @return string
2012          */
2013         protected function escapeLikeInternal( $s ) {
2014                 return addcslashes( $s, '\%_' );
2015         }
2016
2017         public function buildLike() {
2018                 $params = func_get_args();
2019
2020                 if ( count( $params ) > 0 && is_array( $params[0] ) ) {
2021                         $params = $params[0];
2022                 }
2023
2024                 $s = '';
2025
2026                 foreach ( $params as $value ) {
2027                         if ( $value instanceof LikeMatch ) {
2028                                 $s .= $value->toString();
2029                         } else {
2030                                 $s .= $this->escapeLikeInternal( $value );
2031                         }
2032                 }
2033
2034                 return " LIKE {$this->addQuotes( $s )} ";
2035         }
2036
2037         public function anyChar() {
2038                 return new LikeMatch( '_' );
2039         }
2040
2041         public function anyString() {
2042                 return new LikeMatch( '%' );
2043         }
2044
2045         public function nextSequenceValue( $seqName ) {
2046                 return null;
2047         }
2048
2049         /**
2050          * USE INDEX clause. Unlikely to be useful for anything but MySQL. This
2051          * is only needed because a) MySQL must be as efficient as possible due to
2052          * its use on Wikipedia, and b) MySQL 4.0 is kind of dumb sometimes about
2053          * which index to pick. Anyway, other databases might have different
2054          * indexes on a given table. So don't bother overriding this unless you're
2055          * MySQL.
2056          * @param string $index
2057          * @return string
2058          */
2059         public function useIndexClause( $index ) {
2060                 return '';
2061         }
2062
2063         /**
2064          * IGNORE INDEX clause. Unlikely to be useful for anything but MySQL. This
2065          * is only needed because a) MySQL must be as efficient as possible due to
2066          * its use on Wikipedia, and b) MySQL 4.0 is kind of dumb sometimes about
2067          * which index to pick. Anyway, other databases might have different
2068          * indexes on a given table. So don't bother overriding this unless you're
2069          * MySQL.
2070          * @param string $index
2071          * @return string
2072          */
2073         public function ignoreIndexClause( $index ) {
2074                 return '';
2075         }
2076
2077         public function replace( $table, $uniqueIndexes, $rows, $fname = __METHOD__ ) {
2078                 $quotedTable = $this->tableName( $table );
2079
2080                 if ( count( $rows ) == 0 ) {
2081                         return;
2082                 }
2083
2084                 # Single row case
2085                 if ( !is_array( reset( $rows ) ) ) {
2086                         $rows = [ $rows ];
2087                 }
2088
2089                 // @FXIME: this is not atomic, but a trx would break affectedRows()
2090                 foreach ( $rows as $row ) {
2091                         # Delete rows which collide
2092                         if ( $uniqueIndexes ) {
2093                                 $sql = "DELETE FROM $quotedTable WHERE ";
2094                                 $first = true;
2095                                 foreach ( $uniqueIndexes as $index ) {
2096                                         if ( $first ) {
2097                                                 $first = false;
2098                                                 $sql .= '( ';
2099                                         } else {
2100                                                 $sql .= ' ) OR ( ';
2101                                         }
2102                                         if ( is_array( $index ) ) {
2103                                                 $first2 = true;
2104                                                 foreach ( $index as $col ) {
2105                                                         if ( $first2 ) {
2106                                                                 $first2 = false;
2107                                                         } else {
2108                                                                 $sql .= ' AND ';
2109                                                         }
2110                                                         $sql .= $col . '=' . $this->addQuotes( $row[$col] );
2111                                                 }
2112                                         } else {
2113                                                 $sql .= $index . '=' . $this->addQuotes( $row[$index] );
2114                                         }
2115                                 }
2116                                 $sql .= ' )';
2117                                 $this->query( $sql, $fname );
2118                         }
2119
2120                         # Now insert the row
2121                         $this->insert( $table, $row, $fname );
2122                 }
2123         }
2124
2125         /**
2126          * REPLACE query wrapper for MySQL and SQLite, which have a native REPLACE
2127          * statement.
2128          *
2129          * @param string $table Table name
2130          * @param array|string $rows Row(s) to insert
2131          * @param string $fname Caller function name
2132          *
2133          * @return ResultWrapper
2134          */
2135         protected function nativeReplace( $table, $rows, $fname ) {
2136                 $table = $this->tableName( $table );
2137
2138                 # Single row case
2139                 if ( !is_array( reset( $rows ) ) ) {
2140                         $rows = [ $rows ];
2141                 }
2142
2143                 $sql = "REPLACE INTO $table (" . implode( ',', array_keys( $rows[0] ) ) . ') VALUES ';
2144                 $first = true;
2145
2146                 foreach ( $rows as $row ) {
2147                         if ( $first ) {
2148                                 $first = false;
2149                         } else {
2150                                 $sql .= ',';
2151                         }
2152
2153                         $sql .= '(' . $this->makeList( $row ) . ')';
2154                 }
2155
2156                 return $this->query( $sql, $fname );
2157         }
2158
2159         public function upsert( $table, array $rows, array $uniqueIndexes, array $set,
2160                 $fname = __METHOD__
2161         ) {
2162                 if ( !count( $rows ) ) {
2163                         return true; // nothing to do
2164                 }
2165
2166                 if ( !is_array( reset( $rows ) ) ) {
2167                         $rows = [ $rows ];
2168                 }
2169
2170                 if ( count( $uniqueIndexes ) ) {
2171                         $clauses = []; // list WHERE clauses that each identify a single row
2172                         foreach ( $rows as $row ) {
2173                                 foreach ( $uniqueIndexes as $index ) {
2174                                         $index = is_array( $index ) ? $index : [ $index ]; // columns
2175                                         $rowKey = []; // unique key to this row
2176                                         foreach ( $index as $column ) {
2177                                                 $rowKey[$column] = $row[$column];
2178                                         }
2179                                         $clauses[] = $this->makeList( $rowKey, self::LIST_AND );
2180                                 }
2181                         }
2182                         $where = [ $this->makeList( $clauses, self::LIST_OR ) ];
2183                 } else {
2184                         $where = false;
2185                 }
2186
2187                 $useTrx = !$this->mTrxLevel;
2188                 if ( $useTrx ) {
2189                         $this->begin( $fname, self::TRANSACTION_INTERNAL );
2190                 }
2191                 try {
2192                         # Update any existing conflicting row(s)
2193                         if ( $where !== false ) {
2194                                 $ok = $this->update( $table, $set, $where, $fname );
2195                         } else {
2196                                 $ok = true;
2197                         }
2198                         # Now insert any non-conflicting row(s)
2199                         $ok = $this->insert( $table, $rows, $fname, [ 'IGNORE' ] ) && $ok;
2200                 } catch ( Exception $e ) {
2201                         if ( $useTrx ) {
2202                                 $this->rollback( $fname, self::FLUSHING_INTERNAL );
2203                         }
2204                         throw $e;
2205                 }
2206                 if ( $useTrx ) {
2207                         $this->commit( $fname, self::FLUSHING_INTERNAL );
2208                 }
2209
2210                 return $ok;
2211         }
2212
2213         public function deleteJoin( $delTable, $joinTable, $delVar, $joinVar, $conds,
2214                 $fname = __METHOD__
2215         ) {
2216                 if ( !$conds ) {
2217                         throw new DBUnexpectedError( $this, __METHOD__ . ' called with empty $conds' );
2218                 }
2219
2220                 $delTable = $this->tableName( $delTable );
2221                 $joinTable = $this->tableName( $joinTable );
2222                 $sql = "DELETE FROM $delTable WHERE $delVar IN (SELECT $joinVar FROM $joinTable ";
2223                 if ( $conds != '*' ) {
2224                         $sql .= 'WHERE ' . $this->makeList( $conds, self::LIST_AND );
2225                 }
2226                 $sql .= ')';
2227
2228                 $this->query( $sql, $fname );
2229         }
2230
2231         /**
2232          * Returns the size of a text field, or -1 for "unlimited"
2233          *
2234          * @param string $table
2235          * @param string $field
2236          * @return int
2237          */
2238         public function textFieldSize( $table, $field ) {
2239                 $table = $this->tableName( $table );
2240                 $sql = "SHOW COLUMNS FROM $table LIKE \"$field\";";
2241                 $res = $this->query( $sql, __METHOD__ );
2242                 $row = $this->fetchObject( $res );
2243
2244                 $m = [];
2245
2246                 if ( preg_match( '/\((.*)\)/', $row->Type, $m ) ) {
2247                         $size = $m[1];
2248                 } else {
2249                         $size = -1;
2250                 }
2251
2252                 return $size;
2253         }
2254
2255         public function delete( $table, $conds, $fname = __METHOD__ ) {
2256                 if ( !$conds ) {
2257                         throw new DBUnexpectedError( $this, __METHOD__ . ' called with no conditions' );
2258                 }
2259
2260                 $table = $this->tableName( $table );
2261                 $sql = "DELETE FROM $table";
2262
2263                 if ( $conds != '*' ) {
2264                         if ( is_array( $conds ) ) {
2265                                 $conds = $this->makeList( $conds, self::LIST_AND );
2266                         }
2267                         $sql .= ' WHERE ' . $conds;
2268                 }
2269
2270                 return $this->query( $sql, $fname );
2271         }
2272
2273         public function insertSelect(
2274                 $destTable, $srcTable, $varMap, $conds,
2275                 $fname = __METHOD__, $insertOptions = [], $selectOptions = []
2276         ) {
2277                 if ( $this->cliMode ) {
2278                         // For massive migrations with downtime, we don't want to select everything
2279                         // into memory and OOM, so do all this native on the server side if possible.
2280                         return $this->nativeInsertSelect(
2281                                 $destTable,
2282                                 $srcTable,
2283                                 $varMap,
2284                                 $conds,
2285                                 $fname,
2286                                 $insertOptions,
2287                                 $selectOptions
2288                         );
2289                 }
2290
2291                 // For web requests, do a locking SELECT and then INSERT. This puts the SELECT burden
2292                 // on only the master (without needing row-based-replication). It also makes it easy to
2293                 // know how big the INSERT is going to be.
2294                 $fields = [];
2295                 foreach ( $varMap as $dstColumn => $sourceColumnOrSql ) {
2296                         $fields[] = $this->fieldNameWithAlias( $sourceColumnOrSql, $dstColumn );
2297                 }
2298                 $selectOptions[] = 'FOR UPDATE';
2299                 $res = $this->select( $srcTable, implode( ',', $fields ), $conds, $fname, $selectOptions );
2300                 if ( !$res ) {
2301                         return false;
2302                 }
2303
2304                 $rows = [];
2305                 foreach ( $res as $row ) {
2306                         $rows[] = (array)$row;
2307                 }
2308
2309                 return $this->insert( $destTable, $rows, $fname, $insertOptions );
2310         }
2311
2312         public function nativeInsertSelect( $destTable, $srcTable, $varMap, $conds,
2313                 $fname = __METHOD__,
2314                 $insertOptions = [], $selectOptions = []
2315         ) {
2316                 $destTable = $this->tableName( $destTable );
2317
2318                 if ( !is_array( $insertOptions ) ) {
2319                         $insertOptions = [ $insertOptions ];
2320                 }
2321
2322                 $insertOptions = $this->makeInsertOptions( $insertOptions );
2323
2324                 if ( !is_array( $selectOptions ) ) {
2325                         $selectOptions = [ $selectOptions ];
2326                 }
2327
2328                 list( $startOpts, $useIndex, $tailOpts, $ignoreIndex ) = $this->makeSelectOptions(
2329                         $selectOptions );
2330
2331                 if ( is_array( $srcTable ) ) {
2332                         $srcTable = implode( ',', array_map( [ &$this, 'tableName' ], $srcTable ) );
2333                 } else {
2334                         $srcTable = $this->tableName( $srcTable );
2335                 }
2336
2337                 $sql = "INSERT $insertOptions INTO $destTable (" . implode( ',', array_keys( $varMap ) ) . ')' .
2338                         " SELECT $startOpts " . implode( ',', $varMap ) .
2339                         " FROM $srcTable $useIndex $ignoreIndex ";
2340
2341                 if ( $conds != '*' ) {
2342                         if ( is_array( $conds ) ) {
2343                                 $conds = $this->makeList( $conds, self::LIST_AND );
2344                         }
2345                         $sql .= " WHERE $conds";
2346                 }
2347
2348                 $sql .= " $tailOpts";
2349
2350                 return $this->query( $sql, $fname );
2351         }
2352
2353         /**
2354          * Construct a LIMIT query with optional offset. This is used for query
2355          * pages. The SQL should be adjusted so that only the first $limit rows
2356          * are returned. If $offset is provided as well, then the first $offset
2357          * rows should be discarded, and the next $limit rows should be returned.
2358          * If the result of the query is not ordered, then the rows to be returned
2359          * are theoretically arbitrary.
2360          *
2361          * $sql is expected to be a SELECT, if that makes a difference.
2362          *
2363          * The version provided by default works in MySQL and SQLite. It will very
2364          * likely need to be overridden for most other DBMSes.
2365          *
2366          * @param string $sql SQL query we will append the limit too
2367          * @param int $limit The SQL limit
2368          * @param int|bool $offset The SQL offset (default false)
2369          * @throws DBUnexpectedError
2370          * @return string
2371          */
2372         public function limitResult( $sql, $limit, $offset = false ) {
2373                 if ( !is_numeric( $limit ) ) {
2374                         throw new DBUnexpectedError( $this, "Invalid non-numeric limit passed to limitResult()\n" );
2375                 }
2376
2377                 return "$sql LIMIT "
2378                 . ( ( is_numeric( $offset ) && $offset != 0 ) ? "{$offset}," : "" )
2379                 . "{$limit} ";
2380         }
2381
2382         public function unionSupportsOrderAndLimit() {
2383                 return true; // True for almost every DB supported
2384         }
2385
2386         public function unionQueries( $sqls, $all ) {
2387                 $glue = $all ? ') UNION ALL (' : ') UNION (';
2388
2389                 return '(' . implode( $glue, $sqls ) . ')';
2390         }
2391
2392         public function conditional( $cond, $trueVal, $falseVal ) {
2393                 if ( is_array( $cond ) ) {
2394                         $cond = $this->makeList( $cond, self::LIST_AND );
2395                 }
2396
2397                 return " (CASE WHEN $cond THEN $trueVal ELSE $falseVal END) ";
2398         }
2399
2400         public function strreplace( $orig, $old, $new ) {
2401                 return "REPLACE({$orig}, {$old}, {$new})";
2402         }
2403
2404         public function getServerUptime() {
2405                 return 0;
2406         }
2407
2408         public function wasDeadlock() {
2409                 return false;
2410         }
2411
2412         public function wasLockTimeout() {
2413                 return false;
2414         }
2415
2416         public function wasErrorReissuable() {
2417                 return false;
2418         }
2419
2420         public function wasReadOnlyError() {
2421                 return false;
2422         }
2423
2424         /**
2425          * Determines if the given query error was a connection drop
2426          * STUB
2427          *
2428          * @param integer|string $errno
2429          * @return bool
2430          */
2431         public function wasConnectionError( $errno ) {
2432                 return false;
2433         }
2434
2435         /**
2436          * Perform a deadlock-prone transaction.
2437          *
2438          * This function invokes a callback function to perform a set of write
2439          * queries. If a deadlock occurs during the processing, the transaction
2440          * will be rolled back and the callback function will be called again.
2441          *
2442          * Avoid using this method outside of Job or Maintenance classes.
2443          *
2444          * Usage:
2445          *   $dbw->deadlockLoop( callback, ... );
2446          *
2447          * Extra arguments are passed through to the specified callback function.
2448          * This method requires that no transactions are already active to avoid
2449          * causing premature commits or exceptions.
2450          *
2451          * Returns whatever the callback function returned on its successful,
2452          * iteration, or false on error, for example if the retry limit was
2453          * reached.
2454          *
2455          * @return mixed
2456          * @throws DBUnexpectedError
2457          * @throws Exception
2458          */
2459         public function deadlockLoop() {
2460                 $args = func_get_args();
2461                 $function = array_shift( $args );
2462                 $tries = self::DEADLOCK_TRIES;
2463
2464                 $this->begin( __METHOD__ );
2465
2466                 $retVal = null;
2467                 /** @var Exception $e */
2468                 $e = null;
2469                 do {
2470                         try {
2471                                 $retVal = call_user_func_array( $function, $args );
2472                                 break;
2473                         } catch ( DBQueryError $e ) {
2474                                 if ( $this->wasDeadlock() ) {
2475                                         // Retry after a randomized delay
2476                                         usleep( mt_rand( self::DEADLOCK_DELAY_MIN, self::DEADLOCK_DELAY_MAX ) );
2477                                 } else {
2478                                         // Throw the error back up
2479                                         throw $e;
2480                                 }
2481                         }
2482                 } while ( --$tries > 0 );
2483
2484                 if ( $tries <= 0 ) {
2485                         // Too many deadlocks; give up
2486                         $this->rollback( __METHOD__ );
2487                         throw $e;
2488                 } else {
2489                         $this->commit( __METHOD__ );
2490
2491                         return $retVal;
2492                 }
2493         }
2494
2495         public function masterPosWait( DBMasterPos $pos, $timeout ) {
2496                 # Real waits are implemented in the subclass.
2497                 return 0;
2498         }
2499
2500         public function getSlavePos() {
2501                 # Stub
2502                 return false;
2503         }
2504
2505         public function getMasterPos() {
2506                 # Stub
2507                 return false;
2508         }
2509
2510         public function serverIsReadOnly() {
2511                 return false;
2512         }
2513
2514         final public function onTransactionResolution( callable $callback, $fname = __METHOD__ ) {
2515                 if ( !$this->mTrxLevel ) {
2516                         throw new DBUnexpectedError( $this, "No transaction is active." );
2517                 }
2518                 $this->mTrxEndCallbacks[] = [ $callback, $fname ];
2519         }
2520
2521         final public function onTransactionIdle( callable $callback, $fname = __METHOD__ ) {
2522                 $this->mTrxIdleCallbacks[] = [ $callback, $fname ];
2523                 if ( !$this->mTrxLevel ) {
2524                         $this->runOnTransactionIdleCallbacks( self::TRIGGER_IDLE );
2525                 }
2526         }
2527
2528         final public function onTransactionPreCommitOrIdle( callable $callback, $fname = __METHOD__ ) {
2529                 if ( $this->mTrxLevel ) {
2530                         $this->mTrxPreCommitCallbacks[] = [ $callback, $fname ];
2531                 } else {
2532                         // If no transaction is active, then make one for this callback
2533                         $this->startAtomic( __METHOD__ );
2534                         try {
2535                                 call_user_func( $callback );
2536                                 $this->endAtomic( __METHOD__ );
2537                         } catch ( Exception $e ) {
2538                                 $this->rollback( __METHOD__, self::FLUSHING_INTERNAL );
2539                                 throw $e;
2540                         }
2541                 }
2542         }
2543
2544         final public function setTransactionListener( $name, callable $callback = null ) {
2545                 if ( $callback ) {
2546                         $this->mTrxRecurringCallbacks[$name] = $callback;
2547                 } else {
2548                         unset( $this->mTrxRecurringCallbacks[$name] );
2549                 }
2550         }
2551
2552         /**
2553          * Whether to disable running of post-COMMIT/ROLLBACK callbacks
2554          *
2555          * This method should not be used outside of Database/LoadBalancer
2556          *
2557          * @param bool $suppress
2558          * @since 1.28
2559          */
2560         final public function setTrxEndCallbackSuppression( $suppress ) {
2561                 $this->mTrxEndCallbacksSuppressed = $suppress;
2562         }
2563
2564         /**
2565          * Actually run and consume any "on transaction idle/resolution" callbacks.
2566          *
2567          * This method should not be used outside of Database/LoadBalancer
2568          *
2569          * @param integer $trigger IDatabase::TRIGGER_* constant
2570          * @since 1.20
2571          * @throws Exception
2572          */
2573         public function runOnTransactionIdleCallbacks( $trigger ) {
2574                 if ( $this->mTrxEndCallbacksSuppressed ) {
2575                         return;
2576                 }
2577
2578                 $autoTrx = $this->getFlag( DBO_TRX ); // automatic begin() enabled?
2579                 /** @var Exception $e */
2580                 $e = null; // first exception
2581                 do { // callbacks may add callbacks :)
2582                         $callbacks = array_merge(
2583                                 $this->mTrxIdleCallbacks,
2584                                 $this->mTrxEndCallbacks // include "transaction resolution" callbacks
2585                         );
2586                         $this->mTrxIdleCallbacks = []; // consumed (and recursion guard)
2587                         $this->mTrxEndCallbacks = []; // consumed (recursion guard)
2588                         foreach ( $callbacks as $callback ) {
2589                                 try {
2590                                         list( $phpCallback ) = $callback;
2591                                         $this->clearFlag( DBO_TRX ); // make each query its own transaction
2592                                         call_user_func_array( $phpCallback, [ $trigger ] );
2593                                         if ( $autoTrx ) {
2594                                                 $this->setFlag( DBO_TRX ); // restore automatic begin()
2595                                         } else {
2596                                                 $this->clearFlag( DBO_TRX ); // restore auto-commit
2597                                         }
2598                                 } catch ( Exception $ex ) {
2599                                         call_user_func( $this->errorLogger, $ex );
2600                                         $e = $e ?: $ex;
2601                                         // Some callbacks may use startAtomic/endAtomic, so make sure
2602                                         // their transactions are ended so other callbacks don't fail
2603                                         if ( $this->trxLevel() ) {
2604                                                 $this->rollback( __METHOD__, self::FLUSHING_INTERNAL );
2605                                         }
2606                                 }
2607                         }
2608                 } while ( count( $this->mTrxIdleCallbacks ) );
2609
2610                 if ( $e instanceof Exception ) {
2611                         throw $e; // re-throw any first exception
2612                 }
2613         }
2614
2615         /**
2616          * Actually run and consume any "on transaction pre-commit" callbacks.
2617          *
2618          * This method should not be used outside of Database/LoadBalancer
2619          *
2620          * @since 1.22
2621          * @throws Exception
2622          */
2623         public function runOnTransactionPreCommitCallbacks() {
2624                 $e = null; // first exception
2625                 do { // callbacks may add callbacks :)
2626                         $callbacks = $this->mTrxPreCommitCallbacks;
2627                         $this->mTrxPreCommitCallbacks = []; // consumed (and recursion guard)
2628                         foreach ( $callbacks as $callback ) {
2629                                 try {
2630                                         list( $phpCallback ) = $callback;
2631                                         call_user_func( $phpCallback );
2632                                 } catch ( Exception $ex ) {
2633                                         call_user_func( $this->errorLogger, $ex );
2634                                         $e = $e ?: $ex;
2635                                 }
2636                         }
2637                 } while ( count( $this->mTrxPreCommitCallbacks ) );
2638
2639                 if ( $e instanceof Exception ) {
2640                         throw $e; // re-throw any first exception
2641                 }
2642         }
2643
2644         /**
2645          * Actually run any "transaction listener" callbacks.
2646          *
2647          * This method should not be used outside of Database/LoadBalancer
2648          *
2649          * @param integer $trigger IDatabase::TRIGGER_* constant
2650          * @throws Exception
2651          * @since 1.20
2652          */
2653         public function runTransactionListenerCallbacks( $trigger ) {
2654                 if ( $this->mTrxEndCallbacksSuppressed ) {
2655                         return;
2656                 }
2657
2658                 /** @var Exception $e */
2659                 $e = null; // first exception
2660
2661                 foreach ( $this->mTrxRecurringCallbacks as $phpCallback ) {
2662                         try {
2663                                 $phpCallback( $trigger, $this );
2664                         } catch ( Exception $ex ) {
2665                                 call_user_func( $this->errorLogger, $ex );
2666                                 $e = $e ?: $ex;
2667                         }
2668                 }
2669
2670                 if ( $e instanceof Exception ) {
2671                         throw $e; // re-throw any first exception
2672                 }
2673         }
2674
2675         final public function startAtomic( $fname = __METHOD__ ) {
2676                 if ( !$this->mTrxLevel ) {
2677                         $this->begin( $fname, self::TRANSACTION_INTERNAL );
2678                         // If DBO_TRX is set, a series of startAtomic/endAtomic pairs will result
2679                         // in all changes being in one transaction to keep requests transactional.
2680                         if ( !$this->getFlag( DBO_TRX ) ) {
2681                                 $this->mTrxAutomaticAtomic = true;
2682                         }
2683                 }
2684
2685                 $this->mTrxAtomicLevels[] = $fname;
2686         }
2687
2688         final public function endAtomic( $fname = __METHOD__ ) {
2689                 if ( !$this->mTrxLevel ) {
2690                         throw new DBUnexpectedError( $this, "No atomic transaction is open (got $fname)." );
2691                 }
2692                 if ( !$this->mTrxAtomicLevels ||
2693                         array_pop( $this->mTrxAtomicLevels ) !== $fname
2694                 ) {
2695                         throw new DBUnexpectedError( $this, "Invalid atomic section ended (got $fname)." );
2696                 }
2697
2698                 if ( !$this->mTrxAtomicLevels && $this->mTrxAutomaticAtomic ) {
2699                         $this->commit( $fname, self::FLUSHING_INTERNAL );
2700                 }
2701         }
2702
2703         final public function doAtomicSection( $fname, callable $callback ) {
2704                 $this->startAtomic( $fname );
2705                 try {
2706                         $res = call_user_func_array( $callback, [ $this, $fname ] );
2707                 } catch ( Exception $e ) {
2708                         $this->rollback( $fname, self::FLUSHING_INTERNAL );
2709                         throw $e;
2710                 }
2711                 $this->endAtomic( $fname );
2712
2713                 return $res;
2714         }
2715
2716         final public function begin( $fname = __METHOD__, $mode = self::TRANSACTION_EXPLICIT ) {
2717                 // Protect against mismatched atomic section, transaction nesting, and snapshot loss
2718                 if ( $this->mTrxLevel ) {
2719                         if ( $this->mTrxAtomicLevels ) {
2720                                 $levels = implode( ', ', $this->mTrxAtomicLevels );
2721                                 $msg = "$fname: Got explicit BEGIN while atomic section(s) $levels are open.";
2722                                 throw new DBUnexpectedError( $this, $msg );
2723                         } elseif ( !$this->mTrxAutomatic ) {
2724                                 $msg = "$fname: Explicit transaction already active (from {$this->mTrxFname}).";
2725                                 throw new DBUnexpectedError( $this, $msg );
2726                         } else {
2727                                 // @TODO: make this an exception at some point
2728                                 $msg = "$fname: Implicit transaction already active (from {$this->mTrxFname}).";
2729                                 $this->queryLogger->error( $msg );
2730                                 return; // join the main transaction set
2731                         }
2732                 } elseif ( $this->getFlag( DBO_TRX ) && $mode !== self::TRANSACTION_INTERNAL ) {
2733                         // @TODO: make this an exception at some point
2734                         $msg = "$fname: Implicit transaction expected (DBO_TRX set).";
2735                         $this->queryLogger->error( $msg );
2736                         return; // let any writes be in the main transaction
2737                 }
2738
2739                 // Avoid fatals if close() was called
2740                 $this->assertOpen();
2741
2742                 $this->doBegin( $fname );
2743                 $this->mTrxTimestamp = microtime( true );
2744                 $this->mTrxFname = $fname;
2745                 $this->mTrxDoneWrites = false;
2746                 $this->mTrxAutomatic = ( $mode === self::TRANSACTION_INTERNAL );
2747                 $this->mTrxAutomaticAtomic = false;
2748                 $this->mTrxAtomicLevels = [];
2749                 $this->mTrxShortId = sprintf( '%06x', mt_rand( 0, 0xffffff ) );
2750                 $this->mTrxWriteDuration = 0.0;
2751                 $this->mTrxWriteQueryCount = 0;
2752                 $this->mTrxWriteAdjDuration = 0.0;
2753                 $this->mTrxWriteAdjQueryCount = 0;
2754                 $this->mTrxWriteCallers = [];
2755                 // First SELECT after BEGIN will establish the snapshot in REPEATABLE-READ.
2756                 // Get an estimate of the replica DB lag before then, treating estimate staleness
2757                 // as lag itself just to be safe
2758                 $status = $this->getApproximateLagStatus();
2759                 $this->mTrxReplicaLag = $status['lag'] + ( microtime( true ) - $status['since'] );
2760         }
2761
2762         /**
2763          * Issues the BEGIN command to the database server.
2764          *
2765          * @see DatabaseBase::begin()
2766          * @param string $fname
2767          */
2768         protected function doBegin( $fname ) {
2769                 $this->query( 'BEGIN', $fname );
2770                 $this->mTrxLevel = 1;
2771         }
2772
2773         final public function commit( $fname = __METHOD__, $flush = '' ) {
2774                 if ( $this->mTrxLevel && $this->mTrxAtomicLevels ) {
2775                         // There are still atomic sections open. This cannot be ignored
2776                         $levels = implode( ', ', $this->mTrxAtomicLevels );
2777                         throw new DBUnexpectedError(
2778                                 $this,
2779                                 "$fname: Got COMMIT while atomic sections $levels are still open."
2780                         );
2781                 }
2782
2783                 if ( $flush === self::FLUSHING_INTERNAL || $flush === self::FLUSHING_ALL_PEERS ) {
2784                         if ( !$this->mTrxLevel ) {
2785                                 return; // nothing to do
2786                         } elseif ( !$this->mTrxAutomatic ) {
2787                                 throw new DBUnexpectedError(
2788                                         $this,
2789                                         "$fname: Flushing an explicit transaction, getting out of sync."
2790                                 );
2791                         }
2792                 } else {
2793                         if ( !$this->mTrxLevel ) {
2794                                 $this->queryLogger->error( "$fname: No transaction to commit, something got out of sync." );
2795                                 return; // nothing to do
2796                         } elseif ( $this->mTrxAutomatic ) {
2797                                 // @TODO: make this an exception at some point
2798                                 $msg = "$fname: Explicit commit of implicit transaction.";
2799                                 $this->queryLogger->error( $msg );
2800                                 return; // wait for the main transaction set commit round
2801                         }
2802                 }
2803
2804                 // Avoid fatals if close() was called
2805                 $this->assertOpen();
2806
2807                 $this->runOnTransactionPreCommitCallbacks();
2808                 $writeTime = $this->pendingWriteQueryDuration( self::ESTIMATE_DB_APPLY );
2809                 $this->doCommit( $fname );
2810                 if ( $this->mTrxDoneWrites ) {
2811                         $this->mDoneWrites = microtime( true );
2812                         $this->trxProfiler->transactionWritingOut(
2813                                 $this->mServer, $this->mDBname, $this->mTrxShortId, $writeTime );
2814                 }
2815
2816                 $this->runOnTransactionIdleCallbacks( self::TRIGGER_COMMIT );
2817                 $this->runTransactionListenerCallbacks( self::TRIGGER_COMMIT );
2818         }
2819
2820         /**
2821          * Issues the COMMIT command to the database server.
2822          *
2823          * @see DatabaseBase::commit()
2824          * @param string $fname
2825          */
2826         protected function doCommit( $fname ) {
2827                 if ( $this->mTrxLevel ) {
2828                         $this->query( 'COMMIT', $fname );
2829                         $this->mTrxLevel = 0;
2830                 }
2831         }
2832
2833         final public function rollback( $fname = __METHOD__, $flush = '' ) {
2834                 if ( $flush === self::FLUSHING_INTERNAL || $flush === self::FLUSHING_ALL_PEERS ) {
2835                         if ( !$this->mTrxLevel ) {
2836                                 return; // nothing to do
2837                         }
2838                 } else {
2839                         if ( !$this->mTrxLevel ) {
2840                                 $this->queryLogger->error(
2841                                         "$fname: No transaction to rollback, something got out of sync." );
2842                                 return; // nothing to do
2843                         } elseif ( $this->getFlag( DBO_TRX ) ) {
2844                                 throw new DBUnexpectedError(
2845                                         $this,
2846                                         "$fname: Expected mass rollback of all peer databases (DBO_TRX set)."
2847                                 );
2848                         }
2849                 }
2850
2851                 // Avoid fatals if close() was called
2852                 $this->assertOpen();
2853
2854                 $this->doRollback( $fname );
2855                 $this->mTrxAtomicLevels = [];
2856                 if ( $this->mTrxDoneWrites ) {
2857                         $this->trxProfiler->transactionWritingOut(
2858                                 $this->mServer, $this->mDBname, $this->mTrxShortId );
2859                 }
2860
2861                 $this->mTrxIdleCallbacks = []; // clear
2862                 $this->mTrxPreCommitCallbacks = []; // clear
2863                 $this->runOnTransactionIdleCallbacks( self::TRIGGER_ROLLBACK );
2864                 $this->runTransactionListenerCallbacks( self::TRIGGER_ROLLBACK );
2865         }
2866
2867         /**
2868          * Issues the ROLLBACK command to the database server.
2869          *
2870          * @see DatabaseBase::rollback()
2871          * @param string $fname
2872          */
2873         protected function doRollback( $fname ) {
2874                 if ( $this->mTrxLevel ) {
2875                         # Disconnects cause rollback anyway, so ignore those errors
2876                         $ignoreErrors = true;
2877                         $this->query( 'ROLLBACK', $fname, $ignoreErrors );
2878                         $this->mTrxLevel = 0;
2879                 }
2880         }
2881
2882         public function flushSnapshot( $fname = __METHOD__ ) {
2883                 if ( $this->writesOrCallbacksPending() || $this->explicitTrxActive() ) {
2884                         // This only flushes transactions to clear snapshots, not to write data
2885                         $fnames = implode( ', ', $this->pendingWriteAndCallbackCallers() );
2886                         throw new DBUnexpectedError(
2887                                 $this,
2888                                 "$fname: Cannot COMMIT to clear snapshot because writes are pending ($fnames)."
2889                         );
2890                 }
2891
2892                 $this->commit( $fname, self::FLUSHING_INTERNAL );
2893         }
2894
2895         public function explicitTrxActive() {
2896                 return $this->mTrxLevel && ( $this->mTrxAtomicLevels || !$this->mTrxAutomatic );
2897         }
2898
2899         /**
2900          * Creates a new table with structure copied from existing table
2901          * Note that unlike most database abstraction functions, this function does not
2902          * automatically append database prefix, because it works at a lower
2903          * abstraction level.
2904          * The table names passed to this function shall not be quoted (this
2905          * function calls addIdentifierQuotes when needed).
2906          *
2907          * @param string $oldName Name of table whose structure should be copied
2908          * @param string $newName Name of table to be created
2909          * @param bool $temporary Whether the new table should be temporary
2910          * @param string $fname Calling function name
2911          * @throws RuntimeException
2912          * @return bool True if operation was successful
2913          */
2914         public function duplicateTableStructure( $oldName, $newName, $temporary = false,
2915                 $fname = __METHOD__
2916         ) {
2917                 throw new RuntimeException( __METHOD__ . ' is not implemented in descendant class' );
2918         }
2919
2920         function listTables( $prefix = null, $fname = __METHOD__ ) {
2921                 throw new RuntimeException( __METHOD__ . ' is not implemented in descendant class' );
2922         }
2923
2924         /**
2925          * Reset the views process cache set by listViews()
2926          * @since 1.22
2927          */
2928         final public function clearViewsCache() {
2929                 $this->allViews = null;
2930         }
2931
2932         /**
2933          * Lists all the VIEWs in the database
2934          *
2935          * For caching purposes the list of all views should be stored in
2936          * $this->allViews. The process cache can be cleared with clearViewsCache()
2937          *
2938          * @param string $prefix Only show VIEWs with this prefix, eg. unit_test_
2939          * @param string $fname Name of calling function
2940          * @throws RuntimeException
2941          * @return array
2942          * @since 1.22
2943          */
2944         public function listViews( $prefix = null, $fname = __METHOD__ ) {
2945                 throw new RuntimeException( __METHOD__ . ' is not implemented in descendant class' );
2946         }
2947
2948         /**
2949          * Differentiates between a TABLE and a VIEW
2950          *
2951          * @param string $name Name of the database-structure to test.
2952          * @throws RuntimeException
2953          * @return bool
2954          * @since 1.22
2955          */
2956         public function isView( $name ) {
2957                 throw new RuntimeException( __METHOD__ . ' is not implemented in descendant class' );
2958         }
2959
2960         public function timestamp( $ts = 0 ) {
2961                 $t = new ConvertableTimestamp( $ts );
2962                 // Let errors bubble up to avoid putting garbage in the DB
2963                 return $t->getTimestamp( TS_MW );
2964         }
2965
2966         public function timestampOrNull( $ts = null ) {
2967                 if ( is_null( $ts ) ) {
2968                         return null;
2969                 } else {
2970                         return $this->timestamp( $ts );
2971                 }
2972         }
2973
2974         /**
2975          * Take the result from a query, and wrap it in a ResultWrapper if
2976          * necessary. Boolean values are passed through as is, to indicate success
2977          * of write queries or failure.
2978          *
2979          * Once upon a time, DatabaseBase::query() returned a bare MySQL result
2980          * resource, and it was necessary to call this function to convert it to
2981          * a wrapper. Nowadays, raw database objects are never exposed to external
2982          * callers, so this is unnecessary in external code.
2983          *
2984          * @param bool|ResultWrapper|resource|object $result
2985          * @return bool|ResultWrapper
2986          */
2987         protected function resultObject( $result ) {
2988                 if ( !$result ) {
2989                         return false;
2990                 } elseif ( $result instanceof ResultWrapper ) {
2991                         return $result;
2992                 } elseif ( $result === true ) {
2993                         // Successful write query
2994                         return $result;
2995                 } else {
2996                         return new ResultWrapper( $this, $result );
2997                 }
2998         }
2999
3000         public function ping( &$rtt = null ) {
3001                 // Avoid hitting the server if it was hit recently
3002                 if ( $this->isOpen() && ( microtime( true ) - $this->lastPing ) < self::PING_TTL ) {
3003                         if ( !func_num_args() || $this->mRTTEstimate > 0 ) {
3004                                 $rtt = $this->mRTTEstimate;
3005                                 return true; // don't care about $rtt
3006                         }
3007                 }
3008
3009                 // This will reconnect if possible or return false if not
3010                 $this->clearFlag( DBO_TRX, self::REMEMBER_PRIOR );
3011                 $ok = ( $this->query( self::PING_QUERY, __METHOD__, true ) !== false );
3012                 $this->restoreFlags( self::RESTORE_PRIOR );
3013
3014                 if ( $ok ) {
3015                         $rtt = $this->mRTTEstimate;
3016                 }
3017
3018                 return $ok;
3019         }
3020
3021         /**
3022          * @return bool
3023          */
3024         protected function reconnect() {
3025                 $this->closeConnection();
3026                 $this->mOpened = false;
3027                 $this->mConn = false;
3028                 try {
3029                         $this->open( $this->mServer, $this->mUser, $this->mPassword, $this->mDBname );
3030                         $this->lastPing = microtime( true );
3031                         $ok = true;
3032                 } catch ( DBConnectionError $e ) {
3033                         $ok = false;
3034                 }
3035
3036                 return $ok;
3037         }
3038
3039         public function getSessionLagStatus() {
3040                 return $this->getTransactionLagStatus() ?: $this->getApproximateLagStatus();
3041         }
3042
3043         /**
3044          * Get the replica DB lag when the current transaction started
3045          *
3046          * This is useful when transactions might use snapshot isolation
3047          * (e.g. REPEATABLE-READ in innodb), so the "real" lag of that data
3048          * is this lag plus transaction duration. If they don't, it is still
3049          * safe to be pessimistic. This returns null if there is no transaction.
3050          *
3051          * @return array|null ('lag': seconds or false on error, 'since': UNIX timestamp of BEGIN)
3052          * @since 1.27
3053          */
3054         public function getTransactionLagStatus() {
3055                 return $this->mTrxLevel
3056                         ? [ 'lag' => $this->mTrxReplicaLag, 'since' => $this->trxTimestamp() ]
3057                         : null;
3058         }
3059
3060         /**
3061          * Get a replica DB lag estimate for this server
3062          *
3063          * @return array ('lag': seconds or false on error, 'since': UNIX timestamp of estimate)
3064          * @since 1.27
3065          */
3066         public function getApproximateLagStatus() {
3067                 return [
3068                         'lag'   => $this->getLBInfo( 'replica' ) ? $this->getLag() : 0,
3069                         'since' => microtime( true )
3070                 ];
3071         }
3072
3073         /**
3074          * Merge the result of getSessionLagStatus() for several DBs
3075          * using the most pessimistic values to estimate the lag of
3076          * any data derived from them in combination
3077          *
3078          * This is information is useful for caching modules
3079          *
3080          * @see WANObjectCache::set()
3081          * @see WANObjectCache::getWithSetCallback()
3082          *
3083          * @param IDatabase $db1
3084          * @param IDatabase ...
3085          * @return array Map of values:
3086          *   - lag: highest lag of any of the DBs or false on error (e.g. replication stopped)
3087          *   - since: oldest UNIX timestamp of any of the DB lag estimates
3088          *   - pending: whether any of the DBs have uncommitted changes
3089          * @since 1.27
3090          */
3091         public static function getCacheSetOptions( IDatabase $db1 ) {
3092                 $res = [ 'lag' => 0, 'since' => INF, 'pending' => false ];
3093                 foreach ( func_get_args() as $db ) {
3094                         /** @var IDatabase $db */
3095                         $status = $db->getSessionLagStatus();
3096                         if ( $status['lag'] === false ) {
3097                                 $res['lag'] = false;
3098                         } elseif ( $res['lag'] !== false ) {
3099                                 $res['lag'] = max( $res['lag'], $status['lag'] );
3100                         }
3101                         $res['since'] = min( $res['since'], $status['since'] );
3102                         $res['pending'] = $res['pending'] ?: $db->writesPending();
3103                 }
3104
3105                 return $res;
3106         }
3107
3108         public function getLag() {
3109                 return 0;
3110         }
3111
3112         function maxListLen() {
3113                 return 0;
3114         }
3115
3116         public function encodeBlob( $b ) {
3117                 return $b;
3118         }
3119
3120         public function decodeBlob( $b ) {
3121                 if ( $b instanceof Blob ) {
3122                         $b = $b->fetch();
3123                 }
3124                 return $b;
3125         }
3126
3127         public function setSessionOptions( array $options ) {
3128         }
3129
3130         /**
3131          * Read and execute SQL commands from a file.
3132          *
3133          * Returns true on success, error string or exception on failure (depending
3134          * on object's error ignore settings).
3135          *
3136          * @param string $filename File name to open
3137          * @param bool|callable $lineCallback Optional function called before reading each line
3138          * @param bool|callable $resultCallback Optional function called for each MySQL result
3139          * @param bool|string $fname Calling function name or false if name should be
3140          *   generated dynamically using $filename
3141          * @param bool|callable $inputCallback Optional function called for each
3142          *   complete line sent
3143          * @return bool|string
3144          * @throws Exception
3145          */
3146         public function sourceFile(
3147                 $filename, $lineCallback = false, $resultCallback = false, $fname = false, $inputCallback = false
3148         ) {
3149                 MediaWiki\suppressWarnings();
3150                 $fp = fopen( $filename, 'r' );
3151                 MediaWiki\restoreWarnings();
3152
3153                 if ( false === $fp ) {
3154                         throw new RuntimeException( "Could not open \"{$filename}\".\n" );
3155                 }
3156
3157                 if ( !$fname ) {
3158                         $fname = __METHOD__ . "( $filename )";
3159                 }
3160
3161                 try {
3162                         $error = $this->sourceStream( $fp, $lineCallback, $resultCallback, $fname, $inputCallback );
3163                 } catch ( Exception $e ) {
3164                         fclose( $fp );
3165                         throw $e;
3166                 }
3167
3168                 fclose( $fp );
3169
3170                 return $error;
3171         }
3172
3173         public function setSchemaVars( $vars ) {
3174                 $this->mSchemaVars = $vars;
3175         }
3176
3177         /**
3178          * Read and execute commands from an open file handle.
3179          *
3180          * Returns true on success, error string or exception on failure (depending
3181          * on object's error ignore settings).
3182          *
3183          * @param resource $fp File handle
3184          * @param bool|callable $lineCallback Optional function called before reading each query
3185          * @param bool|callable $resultCallback Optional function called for each MySQL result
3186          * @param string $fname Calling function name
3187          * @param bool|callable $inputCallback Optional function called for each complete query sent
3188          * @return bool|string
3189          */
3190         public function sourceStream( $fp, $lineCallback = false, $resultCallback = false,
3191                 $fname = __METHOD__, $inputCallback = false
3192         ) {
3193                 $cmd = '';
3194
3195                 while ( !feof( $fp ) ) {
3196                         if ( $lineCallback ) {
3197                                 call_user_func( $lineCallback );
3198                         }
3199
3200                         $line = trim( fgets( $fp ) );
3201
3202                         if ( $line == '' ) {
3203                                 continue;
3204                         }
3205
3206                         if ( '-' == $line[0] && '-' == $line[1] ) {
3207                                 continue;
3208                         }
3209
3210                         if ( $cmd != '' ) {
3211                                 $cmd .= ' ';
3212                         }
3213
3214                         $done = $this->streamStatementEnd( $cmd, $line );
3215
3216                         $cmd .= "$line\n";
3217
3218                         if ( $done || feof( $fp ) ) {
3219                                 $cmd = $this->replaceVars( $cmd );
3220
3221                                 if ( ( $inputCallback && call_user_func( $inputCallback, $cmd ) ) || !$inputCallback ) {
3222                                         $res = $this->query( $cmd, $fname );
3223
3224                                         if ( $resultCallback ) {
3225                                                 call_user_func( $resultCallback, $res, $this );
3226                                         }
3227
3228                                         if ( false === $res ) {
3229                                                 $err = $this->lastError();
3230
3231                                                 return "Query \"{$cmd}\" failed with error code \"$err\".\n";
3232                                         }
3233                                 }
3234                                 $cmd = '';
3235                         }
3236                 }
3237
3238                 return true;
3239         }
3240
3241         /**
3242          * Called by sourceStream() to check if we've reached a statement end
3243          *
3244          * @param string $sql SQL assembled so far
3245          * @param string $newLine New line about to be added to $sql
3246          * @return bool Whether $newLine contains end of the statement
3247          */
3248         public function streamStatementEnd( &$sql, &$newLine ) {
3249                 if ( $this->delimiter ) {
3250                         $prev = $newLine;
3251                         $newLine = preg_replace( '/' . preg_quote( $this->delimiter, '/' ) . '$/', '', $newLine );
3252                         if ( $newLine != $prev ) {
3253                                 return true;
3254                         }
3255                 }
3256
3257                 return false;
3258         }
3259
3260         /**
3261          * Database independent variable replacement. Replaces a set of variables
3262          * in an SQL statement with their contents as given by $this->getSchemaVars().
3263          *
3264          * Supports '{$var}' `{$var}` and / *$var* / (without the spaces) style variables.
3265          *
3266          * - '{$var}' should be used for text and is passed through the database's
3267          *   addQuotes method.
3268          * - `{$var}` should be used for identifiers (e.g. table and database names).
3269          *   It is passed through the database's addIdentifierQuotes method which
3270          *   can be overridden if the database uses something other than backticks.
3271          * - / *_* / or / *$wgDBprefix* / passes the name that follows through the
3272          *   database's tableName method.
3273          * - / *i* / passes the name that follows through the database's indexName method.
3274          * - In all other cases, / *$var* / is left unencoded. Except for table options,
3275          *   its use should be avoided. In 1.24 and older, string encoding was applied.
3276          *
3277          * @param string $ins SQL statement to replace variables in
3278          * @return string The new SQL statement with variables replaced
3279          */
3280         protected function replaceVars( $ins ) {
3281                 $vars = $this->getSchemaVars();
3282                 return preg_replace_callback(
3283                         '!
3284                                 /\* (\$wgDBprefix|[_i]) \*/ (\w*) | # 1-2. tableName, indexName
3285                                 \'\{\$ (\w+) }\'                  | # 3. addQuotes
3286                                 `\{\$ (\w+) }`                    | # 4. addIdentifierQuotes
3287                                 /\*\$ (\w+) \*/                     # 5. leave unencoded
3288                         !x',
3289                         function ( $m ) use ( $vars ) {
3290                                 // Note: Because of <https://bugs.php.net/bug.php?id=51881>,
3291                                 // check for both nonexistent keys *and* the empty string.
3292                                 if ( isset( $m[1] ) && $m[1] !== '' ) {
3293                                         if ( $m[1] === 'i' ) {
3294                                                 return $this->indexName( $m[2] );
3295                                         } else {
3296                                                 return $this->tableName( $m[2] );
3297                                         }
3298                                 } elseif ( isset( $m[3] ) && $m[3] !== '' && array_key_exists( $m[3], $vars ) ) {
3299                                         return $this->addQuotes( $vars[$m[3]] );
3300                                 } elseif ( isset( $m[4] ) && $m[4] !== '' && array_key_exists( $m[4], $vars ) ) {
3301                                         return $this->addIdentifierQuotes( $vars[$m[4]] );
3302                                 } elseif ( isset( $m[5] ) && $m[5] !== '' && array_key_exists( $m[5], $vars ) ) {
3303                                         return $vars[$m[5]];
3304                                 } else {
3305                                         return $m[0];
3306                                 }
3307                         },
3308                         $ins
3309                 );
3310         }
3311
3312         /**
3313          * Get schema variables. If none have been set via setSchemaVars(), then
3314          * use some defaults from the current object.
3315          *
3316          * @return array
3317          */
3318         protected function getSchemaVars() {
3319                 if ( $this->mSchemaVars ) {
3320                         return $this->mSchemaVars;
3321                 } else {
3322                         return $this->getDefaultSchemaVars();
3323                 }
3324         }
3325
3326         /**
3327          * Get schema variables to use if none have been set via setSchemaVars().
3328          *
3329          * Override this in derived classes to provide variables for tables.sql
3330          * and SQL patch files.
3331          *
3332          * @return array
3333          */
3334         protected function getDefaultSchemaVars() {
3335                 return [];
3336         }
3337
3338         public function lockIsFree( $lockName, $method ) {
3339                 return true;
3340         }
3341
3342         public function lock( $lockName, $method, $timeout = 5 ) {
3343                 $this->mNamedLocksHeld[$lockName] = 1;
3344
3345                 return true;
3346         }
3347
3348         public function unlock( $lockName, $method ) {
3349                 unset( $this->mNamedLocksHeld[$lockName] );
3350
3351                 return true;
3352         }
3353
3354         public function getScopedLockAndFlush( $lockKey, $fname, $timeout ) {
3355                 if ( $this->writesOrCallbacksPending() ) {
3356                         // This only flushes transactions to clear snapshots, not to write data
3357                         $fnames = implode( ', ', $this->pendingWriteAndCallbackCallers() );
3358                         throw new DBUnexpectedError(
3359                                 $this,
3360                                 "$fname: Cannot COMMIT to clear snapshot because writes are pending ($fnames)."
3361                         );
3362                 }
3363
3364                 if ( !$this->lock( $lockKey, $fname, $timeout ) ) {
3365                         return null;
3366                 }
3367
3368                 $unlocker = new ScopedCallback( function () use ( $lockKey, $fname ) {
3369                         if ( $this->trxLevel() ) {
3370                                 // There is a good chance an exception was thrown, causing any early return
3371                                 // from the caller. Let any error handler get a chance to issue rollback().
3372                                 // If there isn't one, let the error bubble up and trigger server-side rollback.
3373                                 $this->onTransactionResolution(
3374                                         function () use ( $lockKey, $fname ) {
3375                                                 $this->unlock( $lockKey, $fname );
3376                                         },
3377                                         $fname
3378                                 );
3379                         } else {
3380                                 $this->unlock( $lockKey, $fname );
3381                         }
3382                 } );
3383
3384                 $this->commit( $fname, self::FLUSHING_INTERNAL );
3385
3386                 return $unlocker;
3387         }
3388
3389         public function namedLocksEnqueue() {
3390                 return false;
3391         }
3392
3393         /**
3394          * Lock specific tables
3395          *
3396          * @param array $read Array of tables to lock for read access
3397          * @param array $write Array of tables to lock for write access
3398          * @param string $method Name of caller
3399          * @param bool $lowPriority Whether to indicate writes to be LOW PRIORITY
3400          * @return bool
3401          */
3402         public function lockTables( $read, $write, $method, $lowPriority = true ) {
3403                 return true;
3404         }
3405
3406         /**
3407          * Unlock specific tables
3408          *
3409          * @param string $method The caller
3410          * @return bool
3411          */
3412         public function unlockTables( $method ) {
3413                 return true;
3414         }
3415
3416         /**
3417          * Delete a table
3418          * @param string $tableName
3419          * @param string $fName
3420          * @return bool|ResultWrapper
3421          * @since 1.18
3422          */
3423         public function dropTable( $tableName, $fName = __METHOD__ ) {
3424                 if ( !$this->tableExists( $tableName, $fName ) ) {
3425                         return false;
3426                 }
3427                 $sql = "DROP TABLE " . $this->tableName( $tableName ) . " CASCADE";
3428
3429                 return $this->query( $sql, $fName );
3430         }
3431
3432         public function getInfinity() {
3433                 return 'infinity';
3434         }
3435
3436         public function encodeExpiry( $expiry ) {
3437                 return ( $expiry == '' || $expiry == 'infinity' || $expiry == $this->getInfinity() )
3438                         ? $this->getInfinity()
3439                         : $this->timestamp( $expiry );
3440         }
3441
3442         public function decodeExpiry( $expiry, $format = TS_MW ) {
3443                 if ( $expiry == '' || $expiry == 'infinity' || $expiry == $this->getInfinity() ) {
3444                         return 'infinity';
3445                 }
3446
3447                 try {
3448                         $t = new ConvertableTimestamp( $expiry );
3449
3450                         return $t->getTimestamp( $format );
3451                 } catch ( TimestampException $e ) {
3452                         return false;
3453                 }
3454         }
3455
3456         public function setBigSelects( $value = true ) {
3457                 // no-op
3458         }
3459
3460         public function isReadOnly() {
3461                 return ( $this->getReadOnlyReason() !== false );
3462         }
3463
3464         /**
3465          * @return string|bool Reason this DB is read-only or false if it is not
3466          */
3467         protected function getReadOnlyReason() {
3468                 $reason = $this->getLBInfo( 'readOnlyReason' );
3469
3470                 return is_string( $reason ) ? $reason : false;
3471         }
3472
3473         public function setTableAliases( array $aliases ) {
3474                 $this->tableAliases = $aliases;
3475         }
3476
3477         /**
3478          * @return bool Whether a DB user is required to access the DB
3479          * @since 1.28
3480          */
3481         protected function requiresDatabaseUser() {
3482                 return true;
3483         }
3484
3485         /**
3486          * @since 1.19
3487          * @return string
3488          */
3489         public function __toString() {
3490                 return (string)$this->mConn;
3491         }
3492
3493         /**
3494          * Called by serialize. Throw an exception when DB connection is serialized.
3495          * This causes problems on some database engines because the connection is
3496          * not restored on unserialize.
3497          */
3498         public function __sleep() {
3499                 throw new RuntimeException( 'Database serialization may cause problems, since ' .
3500                         'the connection is not restored on wakeup.' );
3501         }
3502
3503         /**
3504          * Run a few simple sanity checks
3505          */
3506         public function __destruct() {
3507                 if ( $this->mTrxLevel && $this->mTrxDoneWrites ) {
3508                         trigger_error( "Uncommitted DB writes (transaction from {$this->mTrxFname})." );
3509                 }
3510
3511                 $danglingWriters = $this->pendingWriteAndCallbackCallers();
3512                 if ( $danglingWriters ) {
3513                         $fnames = implode( ', ', $danglingWriters );
3514                         trigger_error( "DB transaction writes or callbacks still pending ($fnames)." );
3515                 }
3516         }
3517 }