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         /** @var array Map of (table name => 1) for TEMPORARY tables */
 207         protected $mSessionTempTables = [];
 208
 209         /** @var IDatabase|null Lazy handle to the master DB this server replicates from */
 210         private $lazyMasterHandle;
 211
 212         /**
 213          * @since 1.21
 214          * @var resource File handle for upgrade
 215          */
 216         protected $fileHandle = null;
 217
 218         /**
 219          * @since 1.22
 220          * @var string[] Process cache of VIEWs names in the database
 221          */
 222         protected $allViews = null;
 223
 224         /** @var float UNIX timestamp */
 225         protected $lastPing = 0.0;
 226
 227         /** @var int[] Prior mFlags values */
 228         private $priorFlags = [];
 229
 230         /** @var object|string Class name or object With profileIn/profileOut methods */
 231         protected $profiler;
 232         /** @var TransactionProfiler */
 233         protected $trxProfiler;
 234
 235         /**
 236          * Constructor and database handle and attempt to connect to the DB server
 237          *
 238          * IDatabase classes should not be constructed directly in external
 239          * code. Database::factory() should be used instead.
 240          *
 241          * @param array $params Parameters passed from Database::factory()
 242          */
 243         function __construct( array $params ) {
 244                 $server = $params['host'];
 245                 $user = $params['user'];
 246                 $password = $params['password'];
 247                 $dbName = $params['dbname'];
 248
 249                 $this->mSchema = $params['schema'];
 250                 $this->mTablePrefix = $params['tablePrefix'];
 251
 252                 $this->cliMode = $params['cliMode'];
 253                 // Agent name is added to SQL queries in a comment, so make sure it can't break out
 254                 $this->agent = str_replace( '/', '-', $params['agent'] );
 255
 256                 $this->mFlags = $params['flags'];
 257                 if ( $this->mFlags & DBO_DEFAULT ) {
 258                         if ( $this->cliMode ) {
 259                                 $this->mFlags &= ~DBO_TRX;
 260                         } else {
 261                                 $this->mFlags |= DBO_TRX;
 262                         }
 263                 }
 264
 265                 $this->mSessionVars = $params['variables'];
 266
 267                 $this->srvCache = isset( $params['srvCache'] )
 268                         ? $params['srvCache']
 269                         : new HashBagOStuff();
 270
 271                 $this->profiler = $params['profiler'];
 272                 $this->trxProfiler = $params['trxProfiler'];
 273                 $this->connLogger = $params['connLogger'];
 274                 $this->queryLogger = $params['queryLogger'];
 275
 276                 // Set initial dummy domain until open() sets the final DB/prefix
 277                 $this->currentDomain = DatabaseDomain::newUnspecified();
 278
 279                 if ( $user ) {
 280                         $this->open( $server, $user, $password, $dbName );
 281                 } elseif ( $this->requiresDatabaseUser() ) {
 282                         throw new InvalidArgumentException( "No database user provided." );
 283                 }
 284
 285                 // Set the domain object after open() sets the relevant fields
 286                 if ( $this->mDBname != '' ) {
 287                         // Domains with server scope but a table prefix are not used by IDatabase classes
 288                         $this->currentDomain = new DatabaseDomain( $this->mDBname, null, $this->mTablePrefix );
 289                 }
 290         }
 291
 292         /**
 293          * Construct a Database subclass instance given a database type and parameters
 294          *
 295          * This also connects to the database immediately upon object construction
 296          *
 297          * @param string $dbType A possible DB type (sqlite, mysql, postgres)
 298          * @param array $p Parameter map with keys:
 299          *   - host : The hostname of the DB server
 300          *   - user : The name of the database user the client operates under
 301          *   - password : The password for the database user
 302          *   - dbname : The name of the database to use where queries do not specify one.
 303          *      The database must exist or an error might be thrown. Setting this to the empty string
 304          *      will avoid any such errors and make the handle have no implicit database scope. This is
 305          *      useful for queries like SHOW STATUS, CREATE DATABASE, or DROP DATABASE. Note that a
 306          *      "database" in Postgres is rougly equivalent to an entire MySQL server. This the domain
 307          *      in which user names and such are defined, e.g. users are database-specific in Postgres.
 308          *   - schema : The database schema to use (if supported). A "schema" in Postgres is roughly
 309          *      equivalent to a "database" in MySQL. Note that MySQL and SQLite do not use schemas.
 310          *   - tablePrefix : Optional table prefix that is implicitly added on to all table names
 311          *      recognized in queries. This can be used in place of schemas for handle site farms.
 312          *   - flags : Optional bitfield of DBO_* constants that define connection, protocol,
 313          *      buffering, and transaction behavior. It is STRONGLY adviced to leave the DBO_DEFAULT
 314          *      flag in place UNLESS this this database simply acts as a key/value store.
 315          *   - driver: Optional name of a specific DB client driver. For MySQL, there is the old
 316          *      'mysql' driver and the newer 'mysqli' driver.
 317          *   - variables: Optional map of session variables to set after connecting. This can be
 318          *      used to adjust lock timeouts or encoding modes and the like.
 319          *   - connLogger: Optional PSR-3 logger interface instance.
 320          *   - queryLogger: Optional PSR-3 logger interface instance.
 321          *   - profiler: Optional class name or object with profileIn()/profileOut() methods.
 322          *      These will be called in query(), using a simplified version of the SQL that also
 323          *      includes the agent as a SQL comment.
 324          *   - trxProfiler: Optional TransactionProfiler instance.
 325          *   - errorLogger: Optional callback that takes an Exception and logs it.
 326          *   - cliMode: Whether to consider the execution context that of a CLI script.
 327          *   - agent: Optional name used to identify the end-user in query profiling/logging.
 328          *   - srvCache: Optional BagOStuff instance to an APC-style cache.
 329          * @return Database|null If the database driver or extension cannot be found
 330          * @throws InvalidArgumentException If the database driver or extension cannot be found
 331          * @since 1.18
 332          */
 333         final public static function factory( $dbType, $p = [] ) {
 334                 static $canonicalDBTypes = [
 335                         'mysql' => [ 'mysqli', 'mysql' ],
 336                         'postgres' => [],
 337                         'sqlite' => [],
 338                         'oracle' => [],
 339                         'mssql' => [],
 340                 ];
 341
 342                 $driver = false;
 343                 $dbType = strtolower( $dbType );
 344                 if ( isset( $canonicalDBTypes[$dbType] ) && $canonicalDBTypes[$dbType] ) {
 345                         $possibleDrivers = $canonicalDBTypes[$dbType];
 346                         if ( !empty( $p['driver'] ) ) {
 347                                 if ( in_array( $p['driver'], $possibleDrivers ) ) {
 348                                         $driver = $p['driver'];
 349                                 } else {
 350                                         throw new InvalidArgumentException( __METHOD__ .
 351                                                 " type '$dbType' does not support driver '{$p['driver']}'" );
 352                                 }
 353                         } else {
 354                                 foreach ( $possibleDrivers as $posDriver ) {
 355                                         if ( extension_loaded( $posDriver ) ) {
 356                                                 $driver = $posDriver;
 357                                                 break;
 358                                         }
 359                                 }
 360                         }
 361                 } else {
 362                         $driver = $dbType;
 363                 }
 364                 if ( $driver === false ) {
 365                         throw new InvalidArgumentException( __METHOD__ .
 366                                 " no viable database extension found for type '$dbType'" );
 367                 }
 368
 369                 $class = 'Database' . ucfirst( $driver );
 370                 if ( class_exists( $class ) && is_subclass_of( $class, 'IDatabase' ) ) {
 371                         // Resolve some defaults for b/c
 372                         $p['host'] = isset( $p['host'] ) ? $p['host'] : false;
 373                         $p['user'] = isset( $p['user'] ) ? $p['user'] : false;
 374                         $p['password'] = isset( $p['password'] ) ? $p['password'] : false;
 375                         $p['dbname'] = isset( $p['dbname'] ) ? $p['dbname'] : false;
 376                         $p['flags'] = isset( $p['flags'] ) ? $p['flags'] : 0;
 377                         $p['variables'] = isset( $p['variables'] ) ? $p['variables'] : [];
 378                         $p['tablePrefix'] = isset( $p['tablePrefix'] ) ? $p['tablePrefix'] : '';
 379                         $p['schema'] = isset( $p['schema'] ) ? $p['schema'] : '';
 380                         $p['cliMode'] = isset( $p['cliMode'] ) ? $p['cliMode'] : ( PHP_SAPI === 'cli' );
 381                         $p['agent'] = isset( $p['agent'] ) ? $p['agent'] : '';
 382                         if ( !isset( $p['connLogger'] ) ) {
 383                                 $p['connLogger'] = new \Psr\Log\NullLogger();
 384                         }
 385                         if ( !isset( $p['queryLogger'] ) ) {
 386                                 $p['queryLogger'] = new \Psr\Log\NullLogger();
 387                         }
 388                         $p['profiler'] = isset( $p['profiler'] ) ? $p['profiler'] : null;
 389                         if ( !isset( $p['trxProfiler'] ) ) {
 390                                 $p['trxProfiler'] = new TransactionProfiler();
 391                         }
 392                         if ( !isset( $p['errorLogger'] ) ) {
 393                                 $p['errorLogger'] = function ( Exception $e ) {
 394                                         trigger_error( get_class( $e ) . ': ' . $e->getMessage(), E_WARNING );
 395                                 };
 396                         }
 397
 398                         $conn = new $class( $p );
 399                 } else {
 400                         $conn = null;
 401                 }
 402
 403                 return $conn;
 404         }
 405
 406         public function setLogger( LoggerInterface $logger ) {
 407                 $this->queryLogger = $logger;
 408         }
 409
 410         public function getServerInfo() {
 411                 return $this->getServerVersion();
 412         }
 413
 414         public function bufferResults( $buffer = null ) {
 415                 $res = !$this->getFlag( DBO_NOBUFFER );
 416                 if ( $buffer !== null ) {
 417                         $buffer ? $this->clearFlag( DBO_NOBUFFER ) : $this->setFlag( DBO_NOBUFFER );
 418                 }
 419
 420                 return $res;
 421         }
 422
 423         /**
 424          * Turns on (false) or off (true) the automatic generation and sending
 425          * of a "we're sorry, but there has been a database error" page on
 426          * database errors. Default is on (false). When turned off, the
 427          * code should use lastErrno() and lastError() to handle the
 428          * situation as appropriate.
 429          *
 430          * Do not use this function outside of the Database classes.
 431          *
 432          * @param null|bool $ignoreErrors
 433          * @return bool The previous value of the flag.
 434          */
 435         protected function ignoreErrors( $ignoreErrors = null ) {
 436                 $res = $this->getFlag( DBO_IGNORE );
 437                 if ( $ignoreErrors !== null ) {
 438                         $ignoreErrors ? $this->setFlag( DBO_IGNORE ) : $this->clearFlag( DBO_IGNORE );
 439                 }
 440
 441                 return $res;
 442         }
 443
 444         public function trxLevel() {
 445                 return $this->mTrxLevel;
 446         }
 447
 448         public function trxTimestamp() {
 449                 return $this->mTrxLevel ? $this->mTrxTimestamp : null;
 450         }
 451
 452         public function tablePrefix( $prefix = null ) {
 453                 $old = $this->mTablePrefix;
 454                 if ( $prefix !== null ) {
 455                         $this->mTablePrefix = $prefix;
 456                         $this->currentDomain = ( $this->mDBname != '' )
 457                                 ? new DatabaseDomain( $this->mDBname, null, $this->mTablePrefix )
 458                                 : DatabaseDomain::newUnspecified();
 459                 }
 460
 461                 return $old;
 462         }
 463
 464         public function dbSchema( $schema = null ) {
 465                 $old = $this->mSchema;
 466                 if ( $schema !== null ) {
 467                         $this->mSchema = $schema;
 468                 }
 469
 470                 return $old;
 471         }
 472
 473         /**
 474          * Set the filehandle to copy write statements to.
 475          *
 476          * @param resource $fh File handle
 477          */
 478         public function setFileHandle( $fh ) {
 479                 $this->fileHandle = $fh;
 480         }
 481
 482         public function getLBInfo( $name = null ) {
 483                 if ( is_null( $name ) ) {
 484                         return $this->mLBInfo;
 485                 } else {
 486                         if ( array_key_exists( $name, $this->mLBInfo ) ) {
 487                                 return $this->mLBInfo[$name];
 488                         } else {
 489                                 return null;
 490                         }
 491                 }
 492         }
 493
 494         public function setLBInfo( $name, $value = null ) {
 495                 if ( is_null( $value ) ) {
 496                         $this->mLBInfo = $name;
 497                 } else {
 498                         $this->mLBInfo[$name] = $value;
 499                 }
 500         }
 501
 502         public function setLazyMasterHandle( IDatabase $conn ) {
 503                 $this->lazyMasterHandle = $conn;
 504         }
 505
 506         /**
 507          * @return IDatabase|null
 508          * @see setLazyMasterHandle()
 509          * @since 1.27
 510          */
 511         public function getLazyMasterHandle() {
 512                 return $this->lazyMasterHandle;
 513         }
 514
 515         public function implicitGroupby() {
 516                 return true;
 517         }
 518
 519         public function implicitOrderby() {
 520                 return true;
 521         }
 522
 523         public function lastQuery() {
 524                 return $this->mLastQuery;
 525         }
 526
 527         public function doneWrites() {
 528                 return (bool)$this->mDoneWrites;
 529         }
 530
 531         public function lastDoneWrites() {
 532                 return $this->mDoneWrites ?: false;
 533         }
 534
 535         public function writesPending() {
 536                 return $this->mTrxLevel && $this->mTrxDoneWrites;
 537         }
 538
 539         public function writesOrCallbacksPending() {
 540                 return $this->mTrxLevel && (
 541                         $this->mTrxDoneWrites || $this->mTrxIdleCallbacks || $this->mTrxPreCommitCallbacks
 542                 );
 543         }
 544
 545         public function pendingWriteQueryDuration( $type = self::ESTIMATE_TOTAL ) {
 546                 if ( !$this->mTrxLevel ) {
 547                         return false;
 548                 } elseif ( !$this->mTrxDoneWrites ) {
 549                         return 0.0;
 550                 }
 551
 552                 switch ( $type ) {
 553                         case self::ESTIMATE_DB_APPLY:
 554                                 $this->ping( $rtt );
 555                                 $rttAdjTotal = $this->mTrxWriteAdjQueryCount * $rtt;
 556                                 $applyTime = max( $this->mTrxWriteAdjDuration - $rttAdjTotal, 0 );
 557                                 // For omitted queries, make them count as something at least
 558                                 $omitted = $this->mTrxWriteQueryCount - $this->mTrxWriteAdjQueryCount;
 559                                 $applyTime += self::TINY_WRITE_SEC * $omitted;
 560
 561                                 return $applyTime;
 562                         default: // everything
 563                                 return $this->mTrxWriteDuration;
 564                 }
 565         }
 566
 567         public function pendingWriteCallers() {
 568                 return $this->mTrxLevel ? $this->mTrxWriteCallers : [];
 569         }
 570
 571         protected function pendingWriteAndCallbackCallers() {
 572                 if ( !$this->mTrxLevel ) {
 573                         return [];
 574                 }
 575
 576                 $fnames = $this->mTrxWriteCallers;
 577                 foreach ( [
 578                         $this->mTrxIdleCallbacks,
 579                         $this->mTrxPreCommitCallbacks,
 580                         $this->mTrxEndCallbacks
 581                 ] as $callbacks ) {
 582                         foreach ( $callbacks as $callback ) {
 583                                 $fnames[] = $callback[1];
 584                         }
 585                 }
 586
 587                 return $fnames;
 588         }
 589
 590         public function isOpen() {
 591                 return $this->mOpened;
 592         }
 593
 594         public function setFlag( $flag, $remember = self::REMEMBER_NOTHING ) {
 595                 if ( $remember === self::REMEMBER_PRIOR ) {
 596                         array_push( $this->priorFlags, $this->mFlags );
 597                 }
 598                 $this->mFlags |= $flag;
 599         }
 600
 601         public function clearFlag( $flag, $remember = self::REMEMBER_NOTHING ) {
 602                 if ( $remember === self::REMEMBER_PRIOR ) {
 603                         array_push( $this->priorFlags, $this->mFlags );
 604                 }
 605                 $this->mFlags &= ~$flag;
 606         }
 607
 608         public function restoreFlags( $state = self::RESTORE_PRIOR ) {
 609                 if ( !$this->priorFlags ) {
 610                         return;
 611                 }
 612
 613                 if ( $state === self::RESTORE_INITIAL ) {
 614                         $this->mFlags = reset( $this->priorFlags );
 615                         $this->priorFlags = [];
 616                 } else {
 617                         $this->mFlags = array_pop( $this->priorFlags );
 618                 }
 619         }
 620
 621         public function getFlag( $flag ) {
 622                 return !!( $this->mFlags & $flag );
 623         }
 624
 625         public function getProperty( $name ) {
 626                 return $this->$name;
 627         }
 628
 629         public function getDomainID() {
 630                 return $this->currentDomain->getId();
 631         }
 632
 633         final public function getWikiID() {
 634                 return $this->getDomainID();
 635         }
 636
 637         /**
 638          * Get information about an index into an object
 639          * @param string $table Table name
 640          * @param string $index Index name
 641          * @param string $fname Calling function name
 642          * @return mixed Database-specific index description class or false if the index does not exist
 643          */
 644         abstract function indexInfo( $table, $index, $fname = __METHOD__ );
 645
 646         /**
 647          * Wrapper for addslashes()
 648          *
 649          * @param string $s String to be slashed.
 650          * @return string Slashed string.
 651          */
 652         abstract function strencode( $s );
 653
 654         protected function installErrorHandler() {
 655                 $this->mPHPError = false;
 656                 $this->htmlErrors = ini_set( 'html_errors', '0' );
 657                 set_error_handler( [ $this, 'connectionerrorLogger' ] );
 658         }
 659
 660         /**
 661          * @return bool|string
 662          */
 663         protected function restoreErrorHandler() {
 664                 restore_error_handler();
 665                 if ( $this->htmlErrors !== false ) {
 666                         ini_set( 'html_errors', $this->htmlErrors );
 667                 }
 668                 if ( $this->mPHPError ) {
 669                         $error = preg_replace( '!\[<a.*</a>\]!', '', $this->mPHPError );
 670                         $error = preg_replace( '!^.*?:\s?(.*)$!', '$1', $error );
 671
 672                         return $error;
 673                 } else {
 674                         return false;
 675                 }
 676         }
 677
 678         /**
 679          * @param int $errno
 680          * @param string $errstr
 681          */
 682         public function connectionerrorLogger( $errno, $errstr ) {
 683                 $this->mPHPError = $errstr;
 684         }
 685
 686         /**
 687          * Create a log context to pass to PSR-3 logger functions.
 688          *
 689          * @param array $extras Additional data to add to context
 690          * @return array
 691          */
 692         protected function getLogContext( array $extras = [] ) {
 693                 return array_merge(
 694                         [
 695                                 'db_server' => $this->mServer,
 696                                 'db_name' => $this->mDBname,
 697                                 'db_user' => $this->mUser,
 698                         ],
 699                         $extras
 700                 );
 701         }
 702
 703         public function close() {
 704                 if ( $this->mConn ) {
 705                         if ( $this->trxLevel() ) {
 706                                 $this->commit( __METHOD__, self::FLUSHING_INTERNAL );
 707                         }
 708
 709                         $closed = $this->closeConnection();
 710                         $this->mConn = false;
 711                 } elseif ( $this->mTrxIdleCallbacks || $this->mTrxEndCallbacks ) { // sanity
 712                         throw new RuntimeException( "Transaction callbacks still pending." );
 713                 } else {
 714                         $closed = true;
 715                 }
 716                 $this->mOpened = false;
 717
 718                 return $closed;
 719         }
 720
 721         /**
 722          * Make sure isOpen() returns true as a sanity check
 723          *
 724          * @throws DBUnexpectedError
 725          */
 726         protected function assertOpen() {
 727                 if ( !$this->isOpen() ) {
 728                         throw new DBUnexpectedError( $this, "DB connection was already closed." );
 729                 }
 730         }
 731
 732         /**
 733          * Closes underlying database connection
 734          * @since 1.20
 735          * @return bool Whether connection was closed successfully
 736          */
 737         abstract protected function closeConnection();
 738
 739         function reportConnectionError( $error = 'Unknown error' ) {
 740                 $myError = $this->lastError();
 741                 if ( $myError ) {
 742                         $error = $myError;
 743                 }
 744
 745                 # New method
 746                 throw new DBConnectionError( $this, $error );
 747         }
 748
 749         /**
 750          * The DBMS-dependent part of query()
 751          *
 752          * @param string $sql SQL query.
 753          * @return ResultWrapper|bool Result object to feed to fetchObject,
 754          *   fetchRow, ...; or false on failure
 755          */
 756         abstract protected function doQuery( $sql );
 757
 758         /**
 759          * Determine whether a query writes to the DB.
 760          * Should return true if unsure.
 761          *
 762          * @param string $sql
 763          * @return bool
 764          */
 765         protected function isWriteQuery( $sql ) {
 766                 return !preg_match(
 767                         '/^(?:SELECT|BEGIN|ROLLBACK|COMMIT|SET|SHOW|EXPLAIN|\(SELECT)\b/i', $sql );
 768         }
 769
 770         /**
 771          * @param $sql
 772          * @return string|null
 773          */
 774         protected function getQueryVerb( $sql ) {
 775                 return preg_match( '/^\s*([a-z]+)/i', $sql, $m ) ? strtoupper( $m[1] ) : null;
 776         }
 777
 778         /**
 779          * Determine whether a SQL statement is sensitive to isolation level.
 780          * A SQL statement is considered transactable if its result could vary
 781          * depending on the transaction isolation level. Operational commands
 782          * such as 'SET' and 'SHOW' are not considered to be transactable.
 783          *
 784          * @param string $sql
 785          * @return bool
 786          */
 787         protected function isTransactableQuery( $sql ) {
 788                 $verb = $this->getQueryVerb( $sql );
 789                 return !in_array( $verb, [ 'BEGIN', 'COMMIT', 'ROLLBACK', 'SHOW', 'SET' ], true );
 790         }
 791
 792         /**
 793          * @param string $sql A SQL query
 794          * @return bool Whether $sql is SQL for creating/dropping a new TEMPORARY table
 795          */
 796         protected function registerTempTableOperation( $sql ) {
 797                 if ( preg_match(
 798                         '/^CREATE\s+TEMPORARY\s+TABLE\s+(?:IF\s+NOT\s+EXISTS\s+)?[`"\']?(\w+)[`"\']?/i',
 799                         $sql,
 800                         $matches
 801                 ) ) {
 802                         $this->mSessionTempTables[$matches[1]] = 1;
 803
 804                         return true;
 805                 } elseif ( preg_match(
 806                         '/^DROP\s+(?:TEMPORARY\s+)?TABLE\s+(?:IF\s+EXISTS\s+)?[`"\']?(\w+)[`"\']?/i',
 807                         $sql,
 808                         $matches
 809                 ) ) {
 810                         unset( $this->mSessionTempTables[$matches[1]] );
 811
 812                         return true;
 813                 } elseif ( preg_match(
 814                         '/^(?:INSERT\s+(?:\w+\s+)?INTO|UPDATE|DELETE\s+FROM)\s+[`"\']?(\w+)[`"\']?/i',
 815                         $sql,
 816                         $matches
 817                 ) ) {
 818                         return isset( $this->mSessionTempTables[$matches[1]] );
 819                 }
 820
 821                 return false;
 822         }
 823
 824         public function query( $sql, $fname = __METHOD__, $tempIgnore = false ) {
 825                 $priorWritesPending = $this->writesOrCallbacksPending();
 826                 $this->mLastQuery = $sql;
 827
 828                 $isWrite = $this->isWriteQuery( $sql ) && !$this->registerTempTableOperation( $sql );
 829                 if ( $isWrite ) {
 830                         $reason = $this->getReadOnlyReason();
 831                         if ( $reason !== false ) {
 832                                 throw new DBReadOnlyError( $this, "Database is read-only: $reason" );
 833                         }
 834                         # Set a flag indicating that writes have been done
 835                         $this->mDoneWrites = microtime( true );
 836                 }
 837
 838                 // Add trace comment to the begin of the sql string, right after the operator.
 839                 // Or, for one-word queries (like "BEGIN" or COMMIT") add it to the end (bug 42598)
 840                 $commentedSql = preg_replace( '/\s|$/', " /* $fname {$this->agent} */ ", $sql, 1 );
 841
 842                 # Start implicit transactions that wrap the request if DBO_TRX is enabled
 843                 if ( !$this->mTrxLevel && $this->getFlag( DBO_TRX )
 844                         && $this->isTransactableQuery( $sql )
 845                 ) {
 846                         $this->begin( __METHOD__ . " ($fname)", self::TRANSACTION_INTERNAL );
 847                         $this->mTrxAutomatic = true;
 848                 }
 849
 850                 # Keep track of whether the transaction has write queries pending
 851                 if ( $this->mTrxLevel && !$this->mTrxDoneWrites && $isWrite ) {
 852                         $this->mTrxDoneWrites = true;
 853                         $this->trxProfiler->transactionWritingIn(
 854                                 $this->mServer, $this->mDBname, $this->mTrxShortId );
 855                 }
 856
 857                 if ( $this->getFlag( DBO_DEBUG ) ) {
 858                         $this->queryLogger->debug( "{$this->mDBname} {$commentedSql}" );
 859                 }
 860
 861                 # Avoid fatals if close() was called
 862                 $this->assertOpen();
 863
 864                 # Send the query to the server
 865                 $ret = $this->doProfiledQuery( $sql, $commentedSql, $isWrite, $fname );
 866
 867                 # Try reconnecting if the connection was lost
 868                 if ( false === $ret && $this->wasErrorReissuable() ) {
 869                         $recoverable = $this->canRecoverFromDisconnect( $sql, $priorWritesPending );
 870                         # Stash the last error values before anything might clear them
 871                         $lastError = $this->lastError();
 872                         $lastErrno = $this->lastErrno();
 873                         # Update state tracking to reflect transaction loss due to disconnection
 874                         $this->handleSessionLoss();
 875                         if ( $this->reconnect() ) {
 876                                 $msg = __METHOD__ . ": lost connection to {$this->getServer()}; reconnected";
 877                                 $this->connLogger->warning( $msg );
 878                                 $this->queryLogger->warning(
 879                                         "$msg:\n" . ( new RuntimeException() )->getTraceAsString() );
 880
 881                                 if ( !$recoverable ) {
 882                                         # Callers may catch the exception and continue to use the DB
 883                                         $this->reportQueryError( $lastError, $lastErrno, $sql, $fname );
 884                                 } else {
 885                                         # Should be safe to silently retry the query
 886                                         $ret = $this->doProfiledQuery( $sql, $commentedSql, $isWrite, $fname );
 887                                 }
 888                         } else {
 889                                 $msg = __METHOD__ . ": lost connection to {$this->getServer()} permanently";
 890                                 $this->connLogger->error( $msg );
 891                         }
 892                 }
 893
 894                 if ( false === $ret ) {
 895                         # Deadlocks cause the entire transaction to abort, not just the statement.
 896                         # http://dev.mysql.com/doc/refman/5.7/en/innodb-error-handling.html
 897                         # https://www.postgresql.org/docs/9.1/static/explicit-locking.html
 898                         if ( $this->wasDeadlock() ) {
 899                                 if ( $this->explicitTrxActive() || $priorWritesPending ) {
 900                                         $tempIgnore = false; // not recoverable
 901                                 }
 902                                 # Update state tracking to reflect transaction loss
 903                                 $this->handleSessionLoss();
 904                         }
 905
 906                         $this->reportQueryError(
 907                                 $this->lastError(), $this->lastErrno(), $sql, $fname, $tempIgnore );
 908                 }
 909
 910                 $res = $this->resultObject( $ret );
 911
 912                 return $res;
 913         }
 914
 915         private function doProfiledQuery( $sql, $commentedSql, $isWrite, $fname ) {
 916                 $isMaster = !is_null( $this->getLBInfo( 'master' ) );
 917                 # generalizeSQL() will probably cut down the query to reasonable
 918                 # logging size most of the time. The substr is really just a sanity check.
 919                 if ( $isMaster ) {
 920                         $queryProf = 'query-m: ' . substr( self::generalizeSQL( $sql ), 0, 255 );
 921                 } else {
 922                         $queryProf = 'query: ' . substr( self::generalizeSQL( $sql ), 0, 255 );
 923                 }
 924
 925                 # Include query transaction state
 926                 $queryProf .= $this->mTrxShortId ? " [TRX#{$this->mTrxShortId}]" : "";
 927
 928                 $startTime = microtime( true );
 929                 if ( $this->profiler ) {
 930                         call_user_func( [ $this->profiler, 'profileIn' ], $queryProf );
 931                 }
 932                 $ret = $this->doQuery( $commentedSql );
 933                 if ( $this->profiler ) {
 934                         call_user_func( [ $this->profiler, 'profileOut' ], $queryProf );
 935                 }
 936                 $queryRuntime = max( microtime( true ) - $startTime, 0.0 );
 937
 938                 unset( $queryProfSection ); // profile out (if set)
 939
 940                 if ( $ret !== false ) {
 941                         $this->lastPing = $startTime;
 942                         if ( $isWrite && $this->mTrxLevel ) {
 943                                 $this->updateTrxWriteQueryTime( $sql, $queryRuntime );
 944                                 $this->mTrxWriteCallers[] = $fname;
 945                         }
 946                 }
 947
 948                 if ( $sql === self::PING_QUERY ) {
 949                         $this->mRTTEstimate = $queryRuntime;
 950                 }
 951
 952                 $this->trxProfiler->recordQueryCompletion(
 953                         $queryProf, $startTime, $isWrite, $this->affectedRows()
 954                 );
 955                 $this->queryLogger->debug( $sql, [
 956                         'method' => $fname,
 957                         'master' => $isMaster,
 958                         'runtime' => $queryRuntime,
 959                 ] );
 960
 961                 return $ret;
 962         }
 963
 964         /**
 965          * Update the estimated run-time of a query, not counting large row lock times
 966          *
 967          * LoadBalancer can be set to rollback transactions that will create huge replication
 968          * lag. It bases this estimate off of pendingWriteQueryDuration(). Certain simple
 969          * queries, like inserting a row can take a long time due to row locking. This method
 970          * uses some simple heuristics to discount those cases.
 971          *
 972          * @param string $sql A SQL write query
 973          * @param float $runtime Total runtime, including RTT
 974          */
 975         private function updateTrxWriteQueryTime( $sql, $runtime ) {
 976                 // Whether this is indicative of replica DB runtime (except for RBR or ws_repl)
 977                 $indicativeOfReplicaRuntime = true;
 978                 if ( $runtime > self::SLOW_WRITE_SEC ) {
 979                         $verb = $this->getQueryVerb( $sql );
 980                         // insert(), upsert(), replace() are fast unless bulky in size or blocked on locks
 981                         if ( $verb === 'INSERT' ) {
 982                                 $indicativeOfReplicaRuntime = $this->affectedRows() > self::SMALL_WRITE_ROWS;
 983                         } elseif ( $verb === 'REPLACE' ) {
 984                                 $indicativeOfReplicaRuntime = $this->affectedRows() > self::SMALL_WRITE_ROWS / 2;
 985                         }
 986                 }
 987
 988                 $this->mTrxWriteDuration += $runtime;
 989                 $this->mTrxWriteQueryCount += 1;
 990                 if ( $indicativeOfReplicaRuntime ) {
 991                         $this->mTrxWriteAdjDuration += $runtime;
 992                         $this->mTrxWriteAdjQueryCount += 1;
 993                 }
 994         }
 995
 996         private function canRecoverFromDisconnect( $sql, $priorWritesPending ) {
 997                 # Transaction dropped; this can mean lost writes, or REPEATABLE-READ snapshots.
 998                 # Dropped connections also mean that named locks are automatically released.
 999                 # Only allow error suppression in autocommit mode or when the lost transaction
1000                 # didn't matter anyway (aside from DBO_TRX snapshot loss).
1001                 if ( $this->mNamedLocksHeld ) {
1002                         return false; // possible critical section violation
1003                 } elseif ( $sql === 'COMMIT' ) {
1004                         return !$priorWritesPending; // nothing written anyway? (T127428)
1005                 } elseif ( $sql === 'ROLLBACK' ) {
1006                         return true; // transaction lost...which is also what was requested :)
1007                 } elseif ( $this->explicitTrxActive() ) {
1008                         return false; // don't drop atomocity
1009                 } elseif ( $priorWritesPending ) {
1010                         return false; // prior writes lost from implicit transaction
1011                 }
1012
1013                 return true;
1014         }
1015
1016         private function handleSessionLoss() {
1017                 $this->mTrxLevel = 0;
1018                 $this->mTrxIdleCallbacks = []; // bug 65263
1019                 $this->mTrxPreCommitCallbacks = []; // bug 65263
1020                 $this->mSessionTempTables = [];
1021                 $this->mNamedLocksHeld = [];
1022                 try {
1023                         // Handle callbacks in mTrxEndCallbacks
1024                         $this->runOnTransactionIdleCallbacks( self::TRIGGER_ROLLBACK );
1025                         $this->runTransactionListenerCallbacks( self::TRIGGER_ROLLBACK );
1026                         return null;
1027                 } catch ( Exception $e ) {
1028                         // Already logged; move on...
1029                         return $e;
1030                 }
1031         }
1032
1033         public function reportQueryError( $error, $errno, $sql, $fname, $tempIgnore = false ) {
1034                 if ( $this->ignoreErrors() || $tempIgnore ) {
1035                         $this->queryLogger->debug( "SQL ERROR (ignored): $error\n" );
1036                 } else {
1037                         $sql1line = mb_substr( str_replace( "\n", "\\n", $sql ), 0, 5 * 1024 );
1038                         $this->queryLogger->error(
1039                                 "{fname}\t{db_server}\t{errno}\t{error}\t{sql1line}",
1040                                 $this->getLogContext( [
1041                                         'method' => __METHOD__,
1042                                         'errno' => $errno,
1043                                         'error' => $error,
1044                                         'sql1line' => $sql1line,
1045                                         'fname' => $fname,
1046                                 ] )
1047                         );
1048                         $this->queryLogger->debug( "SQL ERROR: " . $error . "\n" );
1049                         throw new DBQueryError( $this, $error, $errno, $sql, $fname );
1050                 }
1051         }
1052
1053         public function freeResult( $res ) {
1054         }
1055
1056         public function selectField(
1057                 $table, $var, $cond = '', $fname = __METHOD__, $options = []
1058         ) {
1059                 if ( $var === '*' ) { // sanity
1060                         throw new DBUnexpectedError( $this, "Cannot use a * field: got '$var'" );
1061                 }
1062
1063                 if ( !is_array( $options ) ) {
1064                         $options = [ $options ];
1065                 }
1066
1067                 $options['LIMIT'] = 1;
1068
1069                 $res = $this->select( $table, $var, $cond, $fname, $options );
1070                 if ( $res === false || !$this->numRows( $res ) ) {
1071                         return false;
1072                 }
1073
1074                 $row = $this->fetchRow( $res );
1075
1076                 if ( $row !== false ) {
1077                         return reset( $row );
1078                 } else {
1079                         return false;
1080                 }
1081         }
1082
1083         public function selectFieldValues(
1084                 $table, $var, $cond = '', $fname = __METHOD__, $options = [], $join_conds = []
1085         ) {
1086                 if ( $var === '*' ) { // sanity
1087                         throw new DBUnexpectedError( $this, "Cannot use a * field" );
1088                 } elseif ( !is_string( $var ) ) { // sanity
1089                         throw new DBUnexpectedError( $this, "Cannot use an array of fields" );
1090                 }
1091
1092                 if ( !is_array( $options ) ) {
1093                         $options = [ $options ];
1094                 }
1095
1096                 $res = $this->select( $table, $var, $cond, $fname, $options, $join_conds );
1097                 if ( $res === false ) {
1098                         return false;
1099                 }
1100
1101                 $values = [];
1102                 foreach ( $res as $row ) {
1103                         $values[] = $row->$var;
1104                 }
1105
1106                 return $values;
1107         }
1108
1109         /**
1110          * Returns an optional USE INDEX clause to go after the table, and a
1111          * string to go at the end of the query.
1112          *
1113          * @param array $options Associative array of options to be turned into
1114          *   an SQL query, valid keys are listed in the function.
1115          * @return array
1116          * @see DatabaseBase::select()
1117          */
1118         public function makeSelectOptions( $options ) {
1119                 $preLimitTail = $postLimitTail = '';
1120                 $startOpts = '';
1121
1122                 $noKeyOptions = [];
1123
1124                 foreach ( $options as $key => $option ) {
1125                         if ( is_numeric( $key ) ) {
1126                                 $noKeyOptions[$option] = true;
1127                         }
1128                 }
1129
1130                 $preLimitTail .= $this->makeGroupByWithHaving( $options );
1131
1132                 $preLimitTail .= $this->makeOrderBy( $options );
1133
1134                 // if (isset($options['LIMIT'])) {
1135                 //      $tailOpts .= $this->limitResult('', $options['LIMIT'],
1136                 //              isset($options['OFFSET']) ? $options['OFFSET']
1137                 //              : false);
1138                 // }
1139
1140                 if ( isset( $noKeyOptions['FOR UPDATE'] ) ) {
1141                         $postLimitTail .= ' FOR UPDATE';
1142                 }
1143
1144                 if ( isset( $noKeyOptions['LOCK IN SHARE MODE'] ) ) {
1145                         $postLimitTail .= ' LOCK IN SHARE MODE';
1146                 }
1147
1148                 if ( isset( $noKeyOptions['DISTINCT'] ) || isset( $noKeyOptions['DISTINCTROW'] ) ) {
1149                         $startOpts .= 'DISTINCT';
1150                 }
1151
1152                 # Various MySQL extensions
1153                 if ( isset( $noKeyOptions['STRAIGHT_JOIN'] ) ) {
1154                         $startOpts .= ' /*! STRAIGHT_JOIN */';
1155                 }
1156
1157                 if ( isset( $noKeyOptions['HIGH_PRIORITY'] ) ) {
1158                         $startOpts .= ' HIGH_PRIORITY';
1159                 }
1160
1161                 if ( isset( $noKeyOptions['SQL_BIG_RESULT'] ) ) {
1162                         $startOpts .= ' SQL_BIG_RESULT';
1163                 }
1164
1165                 if ( isset( $noKeyOptions['SQL_BUFFER_RESULT'] ) ) {
1166                         $startOpts .= ' SQL_BUFFER_RESULT';
1167                 }
1168
1169                 if ( isset( $noKeyOptions['SQL_SMALL_RESULT'] ) ) {
1170                         $startOpts .= ' SQL_SMALL_RESULT';
1171                 }
1172
1173                 if ( isset( $noKeyOptions['SQL_CALC_FOUND_ROWS'] ) ) {
1174                         $startOpts .= ' SQL_CALC_FOUND_ROWS';
1175                 }
1176
1177                 if ( isset( $noKeyOptions['SQL_CACHE'] ) ) {
1178                         $startOpts .= ' SQL_CACHE';
1179                 }
1180
1181                 if ( isset( $noKeyOptions['SQL_NO_CACHE'] ) ) {
1182                         $startOpts .= ' SQL_NO_CACHE';
1183                 }
1184
1185                 if ( isset( $options['USE INDEX'] ) && is_string( $options['USE INDEX'] ) ) {
1186                         $useIndex = $this->useIndexClause( $options['USE INDEX'] );
1187                 } else {
1188                         $useIndex = '';
1189                 }
1190                 if ( isset( $options['IGNORE INDEX'] ) && is_string( $options['IGNORE INDEX'] ) ) {
1191                         $ignoreIndex = $this->ignoreIndexClause( $options['IGNORE INDEX'] );
1192                 } else {
1193                         $ignoreIndex = '';
1194                 }
1195
1196                 return [ $startOpts, $useIndex, $preLimitTail, $postLimitTail, $ignoreIndex ];
1197         }
1198
1199         /**
1200          * Returns an optional GROUP BY with an optional HAVING
1201          *
1202          * @param array $options Associative array of options
1203          * @return string
1204          * @see DatabaseBase::select()
1205          * @since 1.21
1206          */
1207         public function makeGroupByWithHaving( $options ) {
1208                 $sql = '';
1209                 if ( isset( $options['GROUP BY'] ) ) {
1210                         $gb = is_array( $options['GROUP BY'] )
1211                                 ? implode( ',', $options['GROUP BY'] )
1212                                 : $options['GROUP BY'];
1213                         $sql .= ' GROUP BY ' . $gb;
1214                 }
1215                 if ( isset( $options['HAVING'] ) ) {
1216                         $having = is_array( $options['HAVING'] )
1217                                 ? $this->makeList( $options['HAVING'], self::LIST_AND )
1218                                 : $options['HAVING'];
1219                         $sql .= ' HAVING ' . $having;
1220                 }
1221
1222                 return $sql;
1223         }
1224
1225         /**
1226          * Returns an optional ORDER BY
1227          *
1228          * @param array $options Associative array of options
1229          * @return string
1230          * @see DatabaseBase::select()
1231          * @since 1.21
1232          */
1233         public function makeOrderBy( $options ) {
1234                 if ( isset( $options['ORDER BY'] ) ) {
1235                         $ob = is_array( $options['ORDER BY'] )
1236                                 ? implode( ',', $options['ORDER BY'] )
1237                                 : $options['ORDER BY'];
1238
1239                         return ' ORDER BY ' . $ob;
1240                 }
1241
1242                 return '';
1243         }
1244
1245         // See IDatabase::select for the docs for this function
1246         public function select( $table, $vars, $conds = '', $fname = __METHOD__,
1247                 $options = [], $join_conds = [] ) {
1248                 $sql = $this->selectSQLText( $table, $vars, $conds, $fname, $options, $join_conds );
1249
1250                 return $this->query( $sql, $fname );
1251         }
1252
1253         public function selectSQLText( $table, $vars, $conds = '', $fname = __METHOD__,
1254                 $options = [], $join_conds = []
1255         ) {
1256                 if ( is_array( $vars ) ) {
1257                         $vars = implode( ',', $this->fieldNamesWithAlias( $vars ) );
1258                 }
1259
1260                 $options = (array)$options;
1261                 $useIndexes = ( isset( $options['USE INDEX'] ) && is_array( $options['USE INDEX'] ) )
1262                         ? $options['USE INDEX']
1263                         : [];
1264                 $ignoreIndexes = ( isset( $options['IGNORE INDEX'] ) && is_array( $options['IGNORE INDEX'] ) )
1265                         ? $options['IGNORE INDEX']
1266                         : [];
1267
1268                 if ( is_array( $table ) ) {
1269                         $from = ' FROM ' .
1270                                 $this->tableNamesWithIndexClauseOrJOIN( $table, $useIndexes, $ignoreIndexes, $join_conds );
1271                 } elseif ( $table != '' ) {
1272                         if ( $table[0] == ' ' ) {
1273                                 $from = ' FROM ' . $table;
1274                         } else {
1275                                 $from = ' FROM ' .
1276                                         $this->tableNamesWithIndexClauseOrJOIN( [ $table ], $useIndexes, $ignoreIndexes, [] );
1277                         }
1278                 } else {
1279                         $from = '';
1280                 }
1281
1282                 list( $startOpts, $useIndex, $preLimitTail, $postLimitTail, $ignoreIndex ) =
1283                         $this->makeSelectOptions( $options );
1284
1285                 if ( !empty( $conds ) ) {
1286                         if ( is_array( $conds ) ) {
1287                                 $conds = $this->makeList( $conds, self::LIST_AND );
1288                         }
1289                         $sql = "SELECT $startOpts $vars $from $useIndex $ignoreIndex WHERE $conds $preLimitTail";
1290                 } else {
1291                         $sql = "SELECT $startOpts $vars $from $useIndex $ignoreIndex $preLimitTail";
1292                 }
1293
1294                 if ( isset( $options['LIMIT'] ) ) {
1295                         $sql = $this->limitResult( $sql, $options['LIMIT'],
1296                                 isset( $options['OFFSET'] ) ? $options['OFFSET'] : false );
1297                 }
1298                 $sql = "$sql $postLimitTail";
1299
1300                 if ( isset( $options['EXPLAIN'] ) ) {
1301                         $sql = 'EXPLAIN ' . $sql;
1302                 }
1303
1304                 return $sql;
1305         }
1306
1307         public function selectRow( $table, $vars, $conds, $fname = __METHOD__,
1308                 $options = [], $join_conds = []
1309         ) {
1310                 $options = (array)$options;
1311                 $options['LIMIT'] = 1;
1312                 $res = $this->select( $table, $vars, $conds, $fname, $options, $join_conds );
1313
1314                 if ( $res === false ) {
1315                         return false;
1316                 }
1317
1318                 if ( !$this->numRows( $res ) ) {
1319                         return false;
1320                 }
1321
1322                 $obj = $this->fetchObject( $res );
1323
1324                 return $obj;
1325         }
1326
1327         public function estimateRowCount(
1328                 $table, $vars = '*', $conds = '', $fname = __METHOD__, $options = []
1329         ) {
1330                 $rows = 0;
1331                 $res = $this->select( $table, [ 'rowcount' => 'COUNT(*)' ], $conds, $fname, $options );
1332
1333                 if ( $res ) {
1334                         $row = $this->fetchRow( $res );
1335                         $rows = ( isset( $row['rowcount'] ) ) ? (int)$row['rowcount'] : 0;
1336                 }
1337
1338                 return $rows;
1339         }
1340
1341         public function selectRowCount(
1342                 $tables, $vars = '*', $conds = '', $fname = __METHOD__, $options = [], $join_conds = []
1343         ) {
1344                 $rows = 0;
1345                 $sql = $this->selectSQLText( $tables, '1', $conds, $fname, $options, $join_conds );
1346                 $res = $this->query( "SELECT COUNT(*) AS rowcount FROM ($sql) tmp_count", $fname );
1347
1348                 if ( $res ) {
1349                         $row = $this->fetchRow( $res );
1350                         $rows = ( isset( $row['rowcount'] ) ) ? (int)$row['rowcount'] : 0;
1351                 }
1352
1353                 return $rows;
1354         }
1355
1356         /**
1357          * Removes most variables from an SQL query and replaces them with X or N for numbers.
1358          * It's only slightly flawed. Don't use for anything important.
1359          *
1360          * @param string $sql A SQL Query
1361          *
1362          * @return string
1363          */
1364         protected static function generalizeSQL( $sql ) {
1365                 # This does the same as the regexp below would do, but in such a way
1366                 # as to avoid crashing php on some large strings.
1367                 # $sql = preg_replace( "/'([^\\\\']|\\\\.)*'|\"([^\\\\\"]|\\\\.)*\"/", "'X'", $sql );
1368
1369                 $sql = str_replace( "\\\\", '', $sql );
1370                 $sql = str_replace( "\\'", '', $sql );
1371                 $sql = str_replace( "\\\"", '', $sql );
1372                 $sql = preg_replace( "/'.*'/s", "'X'", $sql );
1373                 $sql = preg_replace( '/".*"/s', "'X'", $sql );
1374
1375                 # All newlines, tabs, etc replaced by single space
1376                 $sql = preg_replace( '/\s+/', ' ', $sql );
1377
1378                 # All numbers => N,
1379                 # except the ones surrounded by characters, e.g. l10n
1380                 $sql = preg_replace( '/-?\d+(,-?\d+)+/s', 'N,...,N', $sql );
1381                 $sql = preg_replace( '/(?<![a-zA-Z])-?\d+(?![a-zA-Z])/s', 'N', $sql );
1382
1383                 return $sql;
1384         }
1385
1386         public function fieldExists( $table, $field, $fname = __METHOD__ ) {
1387                 $info = $this->fieldInfo( $table, $field );
1388
1389                 return (bool)$info;
1390         }
1391
1392         public function indexExists( $table, $index, $fname = __METHOD__ ) {
1393                 if ( !$this->tableExists( $table ) ) {
1394                         return null;
1395                 }
1396
1397                 $info = $this->indexInfo( $table, $index, $fname );
1398                 if ( is_null( $info ) ) {
1399                         return null;
1400                 } else {
1401                         return $info !== false;
1402                 }
1403         }
1404
1405         public function tableExists( $table, $fname = __METHOD__ ) {
1406                 $tableRaw = $this->tableName( $table, 'raw' );
1407                 if ( isset( $this->mSessionTempTables[$tableRaw] ) ) {
1408                         return true; // already known to exist
1409                 }
1410
1411                 $table = $this->tableName( $table );
1412                 $old = $this->ignoreErrors( true );
1413                 $res = $this->query( "SELECT 1 FROM $table LIMIT 1", $fname );
1414                 $this->ignoreErrors( $old );
1415
1416                 return (bool)$res;
1417         }
1418
1419         public function indexUnique( $table, $index ) {
1420                 $indexInfo = $this->indexInfo( $table, $index );
1421
1422                 if ( !$indexInfo ) {
1423                         return null;
1424                 }
1425
1426                 return !$indexInfo[0]->Non_unique;
1427         }
1428
1429         /**
1430          * Helper for DatabaseBase::insert().
1431          *
1432          * @param array $options
1433          * @return string
1434          */
1435         protected function makeInsertOptions( $options ) {
1436                 return implode( ' ', $options );
1437         }
1438
1439         public function insert( $table, $a, $fname = __METHOD__, $options = [] ) {
1440                 # No rows to insert, easy just return now
1441                 if ( !count( $a ) ) {
1442                         return true;
1443                 }
1444
1445                 $table = $this->tableName( $table );
1446
1447                 if ( !is_array( $options ) ) {
1448                         $options = [ $options ];
1449                 }
1450
1451                 $fh = null;
1452                 if ( isset( $options['fileHandle'] ) ) {
1453                         $fh = $options['fileHandle'];
1454                 }
1455                 $options = $this->makeInsertOptions( $options );
1456
1457                 if ( isset( $a[0] ) && is_array( $a[0] ) ) {
1458                         $multi = true;
1459                         $keys = array_keys( $a[0] );
1460                 } else {
1461                         $multi = false;
1462                         $keys = array_keys( $a );
1463                 }
1464
1465                 $sql = 'INSERT ' . $options .
1466                         " INTO $table (" . implode( ',', $keys ) . ') VALUES ';
1467
1468                 if ( $multi ) {
1469                         $first = true;
1470                         foreach ( $a as $row ) {
1471                                 if ( $first ) {
1472                                         $first = false;
1473                                 } else {
1474                                         $sql .= ',';
1475                                 }
1476                                 $sql .= '(' . $this->makeList( $row ) . ')';
1477                         }
1478                 } else {
1479                         $sql .= '(' . $this->makeList( $a ) . ')';
1480                 }
1481
1482                 if ( $fh !== null && false === fwrite( $fh, $sql ) ) {
1483                         return false;
1484                 } elseif ( $fh !== null ) {
1485                         return true;
1486                 }
1487
1488                 return (bool)$this->query( $sql, $fname );
1489         }
1490
1491         /**
1492          * Make UPDATE options array for DatabaseBase::makeUpdateOptions
1493          *
1494          * @param array $options
1495          * @return array
1496          */
1497         protected function makeUpdateOptionsArray( $options ) {
1498                 if ( !is_array( $options ) ) {
1499                         $options = [ $options ];
1500                 }
1501
1502                 $opts = [];
1503
1504                 if ( in_array( 'IGNORE', $options ) ) {
1505                         $opts[] = 'IGNORE';
1506                 }
1507
1508                 return $opts;
1509         }
1510
1511         /**
1512          * Make UPDATE options for the DatabaseBase::update function
1513          *
1514          * @param array $options The options passed to DatabaseBase::update
1515          * @return string
1516          */
1517         protected function makeUpdateOptions( $options ) {
1518                 $opts = $this->makeUpdateOptionsArray( $options );
1519
1520                 return implode( ' ', $opts );
1521         }
1522
1523         function update( $table, $values, $conds, $fname = __METHOD__, $options = [] ) {
1524                 $table = $this->tableName( $table );
1525                 $opts = $this->makeUpdateOptions( $options );
1526                 $sql = "UPDATE $opts $table SET " . $this->makeList( $values, self::LIST_SET );
1527
1528                 if ( $conds !== [] && $conds !== '*' ) {
1529                         $sql .= " WHERE " . $this->makeList( $conds, self::LIST_AND );
1530                 }
1531
1532                 return $this->query( $sql, $fname );
1533         }
1534
1535         public function makeList( $a, $mode = self::LIST_COMMA ) {
1536                 if ( !is_array( $a ) ) {
1537                         throw new DBUnexpectedError( $this, __METHOD__ . ' called with incorrect parameters' );
1538                 }
1539
1540                 $first = true;
1541                 $list = '';
1542
1543                 foreach ( $a as $field => $value ) {
1544                         if ( !$first ) {
1545                                 if ( $mode == self::LIST_AND ) {
1546                                         $list .= ' AND ';
1547                                 } elseif ( $mode == self::LIST_OR ) {
1548                                         $list .= ' OR ';
1549                                 } else {
1550                                         $list .= ',';
1551                                 }
1552                         } else {
1553                                 $first = false;
1554                         }
1555
1556                         if ( ( $mode == self::LIST_AND || $mode == self::LIST_OR ) && is_numeric( $field ) ) {
1557                                 $list .= "($value)";
1558                         } elseif ( $mode == self::LIST_SET && is_numeric( $field ) ) {
1559                                 $list .= "$value";
1560                         } elseif (
1561                                 ( $mode == self::LIST_AND || $mode == self::LIST_OR ) && is_array( $value )
1562                         ) {
1563                                 // Remove null from array to be handled separately if found
1564                                 $includeNull = false;
1565                                 foreach ( array_keys( $value, null, true ) as $nullKey ) {
1566                                         $includeNull = true;
1567                                         unset( $value[$nullKey] );
1568                                 }
1569                                 if ( count( $value ) == 0 && !$includeNull ) {
1570                                         throw new InvalidArgumentException(
1571                                                 __METHOD__ . ": empty input for field $field" );
1572                                 } elseif ( count( $value ) == 0 ) {
1573                                         // only check if $field is null
1574                                         $list .= "$field IS NULL";
1575                                 } else {
1576                                         // IN clause contains at least one valid element
1577                                         if ( $includeNull ) {
1578                                                 // Group subconditions to ensure correct precedence
1579                                                 $list .= '(';
1580                                         }
1581                                         if ( count( $value ) == 1 ) {
1582                                                 // Special-case single values, as IN isn't terribly efficient
1583                                                 // Don't necessarily assume the single key is 0; we don't
1584                                                 // enforce linear numeric ordering on other arrays here.
1585                                                 $value = array_values( $value )[0];
1586                                                 $list .= $field . " = " . $this->addQuotes( $value );
1587                                         } else {
1588                                                 $list .= $field . " IN (" . $this->makeList( $value ) . ") ";
1589                                         }
1590                                         // if null present in array, append IS NULL
1591                                         if ( $includeNull ) {
1592                                                 $list .= " OR $field IS NULL)";
1593                                         }
1594                                 }
1595                         } elseif ( $value === null ) {
1596                                 if ( $mode == self::LIST_AND || $mode == self::LIST_OR ) {
1597                                         $list .= "$field IS ";
1598                                 } elseif ( $mode == self::LIST_SET ) {
1599                                         $list .= "$field = ";
1600                                 }
1601                                 $list .= 'NULL';
1602                         } else {
1603                                 if (
1604                                         $mode == self::LIST_AND || $mode == self::LIST_OR || $mode == self::LIST_SET
1605                                 ) {
1606                                         $list .= "$field = ";
1607                                 }
1608                                 $list .= $mode == self::LIST_NAMES ? $value : $this->addQuotes( $value );
1609                         }
1610                 }
1611
1612                 return $list;
1613         }
1614
1615         public function makeWhereFrom2d( $data, $baseKey, $subKey ) {
1616                 $conds = [];
1617
1618                 foreach ( $data as $base => $sub ) {
1619                         if ( count( $sub ) ) {
1620                                 $conds[] = $this->makeList(
1621                                         [ $baseKey => $base, $subKey => array_keys( $sub ) ],
1622                                         self::LIST_AND );
1623                         }
1624                 }
1625
1626                 if ( $conds ) {
1627                         return $this->makeList( $conds, self::LIST_OR );
1628                 } else {
1629                         // Nothing to search for...
1630                         return false;
1631                 }
1632         }
1633
1634         /**
1635          * Return aggregated value alias
1636          *
1637          * @param array $valuedata
1638          * @param string $valuename
1639          *
1640          * @return string
1641          */
1642         public function aggregateValue( $valuedata, $valuename = 'value' ) {
1643                 return $valuename;
1644         }
1645
1646         public function bitNot( $field ) {
1647                 return "(~$field)";
1648         }
1649
1650         public function bitAnd( $fieldLeft, $fieldRight ) {
1651                 return "($fieldLeft & $fieldRight)";
1652         }
1653
1654         public function bitOr( $fieldLeft, $fieldRight ) {
1655                 return "($fieldLeft | $fieldRight)";
1656         }
1657
1658         public function buildConcat( $stringList ) {
1659                 return 'CONCAT(' . implode( ',', $stringList ) . ')';
1660         }
1661
1662         public function buildGroupConcatField(
1663                 $delim, $table, $field, $conds = '', $join_conds = []
1664         ) {
1665                 $fld = "GROUP_CONCAT($field SEPARATOR " . $this->addQuotes( $delim ) . ')';
1666
1667                 return '(' . $this->selectSQLText( $table, $fld, $conds, null, [], $join_conds ) . ')';
1668         }
1669
1670         /**
1671          * @param string $field Field or column to cast
1672          * @return string
1673          * @since 1.28
1674          */
1675         public function buildStringCast( $field ) {
1676                 return $field;
1677         }
1678
1679         public function selectDB( $db ) {
1680                 # Stub. Shouldn't cause serious problems if it's not overridden, but
1681                 # if your database engine supports a concept similar to MySQL's
1682                 # databases you may as well.
1683                 $this->mDBname = $db;
1684
1685                 return true;
1686         }
1687
1688         public function getDBname() {
1689                 return $this->mDBname;
1690         }
1691
1692         public function getServer() {
1693                 return $this->mServer;
1694         }
1695
1696         /**
1697          * Format a table name ready for use in constructing an SQL query
1698          *
1699          * This does two important things: it quotes the table names to clean them up,
1700          * and it adds a table prefix if only given a table name with no quotes.
1701          *
1702          * All functions of this object which require a table name call this function
1703          * themselves. Pass the canonical name to such functions. This is only needed
1704          * when calling query() directly.
1705          *
1706          * @note This function does not sanitize user input. It is not safe to use
1707          *   this function to escape user input.
1708          * @param string $name Database table name
1709          * @param string $format One of:
1710          *   quoted - Automatically pass the table name through addIdentifierQuotes()
1711          *            so that it can be used in a query.
1712          *   raw - Do not add identifier quotes to the table name
1713          * @return string Full database name
1714          */
1715         public function tableName( $name, $format = 'quoted' ) {
1716                 # Skip the entire process when we have a string quoted on both ends.
1717                 # Note that we check the end so that we will still quote any use of
1718                 # use of `database`.table. But won't break things if someone wants
1719                 # to query a database table with a dot in the name.
1720                 if ( $this->isQuotedIdentifier( $name ) ) {
1721                         return $name;
1722                 }
1723
1724                 # Lets test for any bits of text that should never show up in a table
1725                 # name. Basically anything like JOIN or ON which are actually part of
1726                 # SQL queries, but may end up inside of the table value to combine
1727                 # sql. Such as how the API is doing.
1728                 # Note that we use a whitespace test rather than a \b test to avoid
1729                 # any remote case where a word like on may be inside of a table name
1730                 # surrounded by symbols which may be considered word breaks.
1731                 if ( preg_match( '/(^|\s)(DISTINCT|JOIN|ON|AS)(\s|$)/i', $name ) !== 0 ) {
1732                         return $name;
1733                 }
1734
1735                 # Split database and table into proper variables.
1736                 # We reverse the explode so that database.table and table both output
1737                 # the correct table.
1738                 $dbDetails = explode( '.', $name, 3 );
1739                 if ( count( $dbDetails ) == 3 ) {
1740                         list( $database, $schema, $table ) = $dbDetails;
1741                         # We don't want any prefix added in this case
1742                         $prefix = '';
1743                 } elseif ( count( $dbDetails ) == 2 ) {
1744                         list( $database, $table ) = $dbDetails;
1745                         # We don't want any prefix added in this case
1746                         # In dbs that support it, $database may actually be the schema
1747                         # but that doesn't affect any of the functionality here
1748                         $prefix = '';
1749                         $schema = '';
1750                 } else {
1751                         list( $table ) = $dbDetails;
1752                         if ( isset( $this->tableAliases[$table] ) ) {
1753                                 $database = $this->tableAliases[$table]['dbname'];
1754                                 $schema = is_string( $this->tableAliases[$table]['schema'] )
1755                                         ? $this->tableAliases[$table]['schema']
1756                                         : $this->mSchema;
1757                                 $prefix = is_string( $this->tableAliases[$table]['prefix'] )
1758                                         ? $this->tableAliases[$table]['prefix']
1759                                         : $this->mTablePrefix;
1760                         } else {
1761                                 $database = '';
1762                                 $schema = $this->mSchema; # Default schema
1763                                 $prefix = $this->mTablePrefix; # Default prefix
1764                         }
1765                 }
1766
1767                 # Quote $table and apply the prefix if not quoted.
1768                 # $tableName might be empty if this is called from Database::replaceVars()
1769                 $tableName = "{$prefix}{$table}";
1770                 if ( $format == 'quoted'
1771                         && !$this->isQuotedIdentifier( $tableName ) && $tableName !== ''
1772                 ) {
1773                         $tableName = $this->addIdentifierQuotes( $tableName );
1774                 }
1775
1776                 # Quote $schema and merge it with the table name if needed
1777                 if ( strlen( $schema ) ) {
1778                         if ( $format == 'quoted' && !$this->isQuotedIdentifier( $schema ) ) {
1779                                 $schema = $this->addIdentifierQuotes( $schema );
1780                         }
1781                         $tableName = $schema . '.' . $tableName;
1782                 }
1783
1784                 # Quote $database and merge it with the table name if needed
1785                 if ( $database !== '' ) {
1786                         if ( $format == 'quoted' && !$this->isQuotedIdentifier( $database ) ) {
1787                                 $database = $this->addIdentifierQuotes( $database );
1788                         }
1789                         $tableName = $database . '.' . $tableName;
1790                 }
1791
1792                 return $tableName;
1793         }
1794
1795         /**
1796          * Fetch a number of table names into an array
1797          * This is handy when you need to construct SQL for joins
1798          *
1799          * Example:
1800          * extract( $dbr->tableNames( 'user', 'watchlist' ) );
1801          * $sql = "SELECT wl_namespace,wl_title FROM $watchlist,$user
1802          *         WHERE wl_user=user_id AND wl_user=$nameWithQuotes";
1803          *
1804          * @return array
1805          */
1806         public function tableNames() {
1807                 $inArray = func_get_args();
1808                 $retVal = [];
1809
1810                 foreach ( $inArray as $name ) {
1811                         $retVal[$name] = $this->tableName( $name );
1812                 }
1813
1814                 return $retVal;
1815         }
1816
1817         /**
1818          * Fetch a number of table names into an zero-indexed numerical array
1819          * This is handy when you need to construct SQL for joins
1820          *
1821          * Example:
1822          * list( $user, $watchlist ) = $dbr->tableNamesN( 'user', 'watchlist' );
1823          * $sql = "SELECT wl_namespace,wl_title FROM $watchlist,$user
1824          *         WHERE wl_user=user_id AND wl_user=$nameWithQuotes";
1825          *
1826          * @return array
1827          */
1828         public function tableNamesN() {
1829                 $inArray = func_get_args();
1830                 $retVal = [];
1831
1832                 foreach ( $inArray as $name ) {
1833                         $retVal[] = $this->tableName( $name );
1834                 }
1835
1836                 return $retVal;
1837         }
1838
1839         /**
1840          * Get an aliased table name
1841          * e.g. tableName AS newTableName
1842          *
1843          * @param string $name Table name, see tableName()
1844          * @param string|bool $alias Alias (optional)
1845          * @return string SQL name for aliased table. Will not alias a table to its own name
1846          */
1847         public function tableNameWithAlias( $name, $alias = false ) {
1848                 if ( !$alias || $alias == $name ) {
1849                         return $this->tableName( $name );
1850                 } else {
1851                         return $this->tableName( $name ) . ' ' . $this->addIdentifierQuotes( $alias );
1852                 }
1853         }
1854
1855         /**
1856          * Gets an array of aliased table names
1857          *
1858          * @param array $tables [ [alias] => table ]
1859          * @return string[] See tableNameWithAlias()
1860          */
1861         public function tableNamesWithAlias( $tables ) {
1862                 $retval = [];
1863                 foreach ( $tables as $alias => $table ) {
1864                         if ( is_numeric( $alias ) ) {
1865                                 $alias = $table;
1866                         }
1867                         $retval[] = $this->tableNameWithAlias( $table, $alias );
1868                 }
1869
1870                 return $retval;
1871         }
1872
1873         /**
1874          * Get an aliased field name
1875          * e.g. fieldName AS newFieldName
1876          *
1877          * @param string $name Field name
1878          * @param string|bool $alias Alias (optional)
1879          * @return string SQL name for aliased field. Will not alias a field to its own name
1880          */
1881         public function fieldNameWithAlias( $name, $alias = false ) {
1882                 if ( !$alias || (string)$alias === (string)$name ) {
1883                         return $name;
1884                 } else {
1885                         return $name . ' AS ' . $this->addIdentifierQuotes( $alias ); // PostgreSQL needs AS
1886                 }
1887         }
1888
1889         /**
1890          * Gets an array of aliased field names
1891          *
1892          * @param array $fields [ [alias] => field ]
1893          * @return string[] See fieldNameWithAlias()
1894          */
1895         public function fieldNamesWithAlias( $fields ) {
1896                 $retval = [];
1897                 foreach ( $fields as $alias => $field ) {
1898                         if ( is_numeric( $alias ) ) {
1899                                 $alias = $field;
1900                         }
1901                         $retval[] = $this->fieldNameWithAlias( $field, $alias );
1902                 }
1903
1904                 return $retval;
1905         }
1906
1907         /**
1908          * Get the aliased table name clause for a FROM clause
1909          * which might have a JOIN and/or USE INDEX or IGNORE INDEX clause
1910          *
1911          * @param array $tables ( [alias] => table )
1912          * @param array $use_index Same as for select()
1913          * @param array $ignore_index Same as for select()
1914          * @param array $join_conds Same as for select()
1915          * @return string
1916          */
1917         protected function tableNamesWithIndexClauseOrJOIN(
1918                 $tables, $use_index = [], $ignore_index = [], $join_conds = []
1919         ) {
1920                 $ret = [];
1921                 $retJOIN = [];
1922                 $use_index = (array)$use_index;
1923                 $ignore_index = (array)$ignore_index;
1924                 $join_conds = (array)$join_conds;
1925
1926                 foreach ( $tables as $alias => $table ) {
1927                         if ( !is_string( $alias ) ) {
1928                                 // No alias? Set it equal to the table name
1929                                 $alias = $table;
1930                         }
1931                         // Is there a JOIN clause for this table?
1932                         if ( isset( $join_conds[$alias] ) ) {
1933                                 list( $joinType, $conds ) = $join_conds[$alias];
1934                                 $tableClause = $joinType;
1935                                 $tableClause .= ' ' . $this->tableNameWithAlias( $table, $alias );
1936                                 if ( isset( $use_index[$alias] ) ) { // has USE INDEX?
1937                                         $use = $this->useIndexClause( implode( ',', (array)$use_index[$alias] ) );
1938                                         if ( $use != '' ) {
1939                                                 $tableClause .= ' ' . $use;
1940                                         }
1941                                 }
1942                                 if ( isset( $ignore_index[$alias] ) ) { // has IGNORE INDEX?
1943                                         $ignore = $this->ignoreIndexClause( implode( ',', (array)$ignore_index[$alias] ) );
1944                                         if ( $ignore != '' ) {
1945                                                 $tableClause .= ' ' . $ignore;
1946                                         }
1947                                 }
1948                                 $on = $this->makeList( (array)$conds, self::LIST_AND );
1949                                 if ( $on != '' ) {
1950                                         $tableClause .= ' ON (' . $on . ')';
1951                                 }
1952
1953                                 $retJOIN[] = $tableClause;
1954                         } elseif ( isset( $use_index[$alias] ) ) {
1955                                 // Is there an INDEX clause for this table?
1956                                 $tableClause = $this->tableNameWithAlias( $table, $alias );
1957                                 $tableClause .= ' ' . $this->useIndexClause(
1958                                                 implode( ',', (array)$use_index[$alias] )
1959                                         );
1960
1961                                 $ret[] = $tableClause;
1962                         } elseif ( isset( $ignore_index[$alias] ) ) {
1963                                 // Is there an INDEX clause for this table?
1964                                 $tableClause = $this->tableNameWithAlias( $table, $alias );
1965                                 $tableClause .= ' ' . $this->ignoreIndexClause(
1966                                                 implode( ',', (array)$ignore_index[$alias] )
1967                                         );
1968
1969                                 $ret[] = $tableClause;
1970                         } else {
1971                                 $tableClause = $this->tableNameWithAlias( $table, $alias );
1972
1973                                 $ret[] = $tableClause;
1974                         }
1975                 }
1976
1977                 // We can't separate explicit JOIN clauses with ',', use ' ' for those
1978                 $implicitJoins = !empty( $ret ) ? implode( ',', $ret ) : "";
1979                 $explicitJoins = !empty( $retJOIN ) ? implode( ' ', $retJOIN ) : "";
1980
1981                 // Compile our final table clause
1982                 return implode( ' ', [ $implicitJoins, $explicitJoins ] );
1983         }
1984
1985         /**
1986          * Get the name of an index in a given table.
1987          *
1988          * @param string $index
1989          * @return string
1990          */
1991         protected function indexName( $index ) {
1992                 // Backwards-compatibility hack
1993                 $renamed = [
1994                         'ar_usertext_timestamp' => 'usertext_timestamp',
1995                         'un_user_id' => 'user_id',
1996                         'un_user_ip' => 'user_ip',
1997                 ];
1998
1999                 if ( isset( $renamed[$index] ) ) {
2000                         return $renamed[$index];
2001                 } else {
2002                         return $index;
2003                 }
2004         }
2005
2006         public function addQuotes( $s ) {
2007                 if ( $s instanceof Blob ) {
2008                         $s = $s->fetch();
2009                 }
2010                 if ( $s === null ) {
2011                         return 'NULL';
2012                 } else {
2013                         # This will also quote numeric values. This should be harmless,
2014                         # and protects against weird problems that occur when they really
2015                         # _are_ strings such as article titles and string->number->string
2016                         # conversion is not 1:1.
2017                         return "'" . $this->strencode( $s ) . "'";
2018                 }
2019         }
2020
2021         /**
2022          * Quotes an identifier using `backticks` or "double quotes" depending on the database type.
2023          * MySQL uses `backticks` while basically everything else uses double quotes.
2024          * Since MySQL is the odd one out here the double quotes are our generic
2025          * and we implement backticks in DatabaseMysql.
2026          *
2027          * @param string $s
2028          * @return string
2029          */
2030         public function addIdentifierQuotes( $s ) {
2031                 return '"' . str_replace( '"', '""', $s ) . '"';
2032         }
2033
2034         /**
2035          * Returns if the given identifier looks quoted or not according to
2036          * the database convention for quoting identifiers .
2037          *
2038          * @note Do not use this to determine if untrusted input is safe.
2039          *   A malicious user can trick this function.
2040          * @param string $name
2041          * @return bool
2042          */
2043         public function isQuotedIdentifier( $name ) {
2044                 return $name[0] == '"' && substr( $name, -1, 1 ) == '"';
2045         }
2046
2047         /**
2048          * @param string $s
2049          * @return string
2050          */
2051         protected function escapeLikeInternal( $s ) {
2052                 return addcslashes( $s, '\%_' );
2053         }
2054
2055         public function buildLike() {
2056                 $params = func_get_args();
2057
2058                 if ( count( $params ) > 0 && is_array( $params[0] ) ) {
2059                         $params = $params[0];
2060                 }
2061
2062                 $s = '';
2063
2064                 foreach ( $params as $value ) {
2065                         if ( $value instanceof LikeMatch ) {
2066                                 $s .= $value->toString();
2067                         } else {
2068                                 $s .= $this->escapeLikeInternal( $value );
2069                         }
2070                 }
2071
2072                 return " LIKE {$this->addQuotes( $s )} ";
2073         }
2074
2075         public function anyChar() {
2076                 return new LikeMatch( '_' );
2077         }
2078
2079         public function anyString() {
2080                 return new LikeMatch( '%' );
2081         }
2082
2083         public function nextSequenceValue( $seqName ) {
2084                 return null;
2085         }
2086
2087         /**
2088          * USE INDEX clause. Unlikely to be useful for anything but MySQL. This
2089          * is only needed because a) MySQL must be as efficient as possible due to
2090          * its use on Wikipedia, and b) MySQL 4.0 is kind of dumb sometimes about
2091          * which index to pick. Anyway, other databases might have different
2092          * indexes on a given table. So don't bother overriding this unless you're
2093          * MySQL.
2094          * @param string $index
2095          * @return string
2096          */
2097         public function useIndexClause( $index ) {
2098                 return '';
2099         }
2100
2101         /**
2102          * IGNORE INDEX clause. Unlikely to be useful for anything but MySQL. This
2103          * is only needed because a) MySQL must be as efficient as possible due to
2104          * its use on Wikipedia, and b) MySQL 4.0 is kind of dumb sometimes about
2105          * which index to pick. Anyway, other databases might have different
2106          * indexes on a given table. So don't bother overriding this unless you're
2107          * MySQL.
2108          * @param string $index
2109          * @return string
2110          */
2111         public function ignoreIndexClause( $index ) {
2112                 return '';
2113         }
2114
2115         public function replace( $table, $uniqueIndexes, $rows, $fname = __METHOD__ ) {
2116                 $quotedTable = $this->tableName( $table );
2117
2118                 if ( count( $rows ) == 0 ) {
2119                         return;
2120                 }
2121
2122                 # Single row case
2123                 if ( !is_array( reset( $rows ) ) ) {
2124                         $rows = [ $rows ];
2125                 }
2126
2127                 // @FXIME: this is not atomic, but a trx would break affectedRows()
2128                 foreach ( $rows as $row ) {
2129                         # Delete rows which collide
2130                         if ( $uniqueIndexes ) {
2131                                 $sql = "DELETE FROM $quotedTable WHERE ";
2132                                 $first = true;
2133                                 foreach ( $uniqueIndexes as $index ) {
2134                                         if ( $first ) {
2135                                                 $first = false;
2136                                                 $sql .= '( ';
2137                                         } else {
2138                                                 $sql .= ' ) OR ( ';
2139                                         }
2140                                         if ( is_array( $index ) ) {
2141                                                 $first2 = true;
2142                                                 foreach ( $index as $col ) {
2143                                                         if ( $first2 ) {
2144                                                                 $first2 = false;
2145                                                         } else {
2146                                                                 $sql .= ' AND ';
2147                                                         }
2148                                                         $sql .= $col . '=' . $this->addQuotes( $row[$col] );
2149                                                 }
2150                                         } else {
2151                                                 $sql .= $index . '=' . $this->addQuotes( $row[$index] );
2152                                         }
2153                                 }
2154                                 $sql .= ' )';
2155                                 $this->query( $sql, $fname );
2156                         }
2157
2158                         # Now insert the row
2159                         $this->insert( $table, $row, $fname );
2160                 }
2161         }
2162
2163         /**
2164          * REPLACE query wrapper for MySQL and SQLite, which have a native REPLACE
2165          * statement.
2166          *
2167          * @param string $table Table name
2168          * @param array|string $rows Row(s) to insert
2169          * @param string $fname Caller function name
2170          *
2171          * @return ResultWrapper
2172          */
2173         protected function nativeReplace( $table, $rows, $fname ) {
2174                 $table = $this->tableName( $table );
2175
2176                 # Single row case
2177                 if ( !is_array( reset( $rows ) ) ) {
2178                         $rows = [ $rows ];
2179                 }
2180
2181                 $sql = "REPLACE INTO $table (" . implode( ',', array_keys( $rows[0] ) ) . ') VALUES ';
2182                 $first = true;
2183
2184                 foreach ( $rows as $row ) {
2185                         if ( $first ) {
2186                                 $first = false;
2187                         } else {
2188                                 $sql .= ',';
2189                         }
2190
2191                         $sql .= '(' . $this->makeList( $row ) . ')';
2192                 }
2193
2194                 return $this->query( $sql, $fname );
2195         }
2196
2197         public function upsert( $table, array $rows, array $uniqueIndexes, array $set,
2198                 $fname = __METHOD__
2199         ) {
2200                 if ( !count( $rows ) ) {
2201                         return true; // nothing to do
2202                 }
2203
2204                 if ( !is_array( reset( $rows ) ) ) {
2205                         $rows = [ $rows ];
2206                 }
2207
2208                 if ( count( $uniqueIndexes ) ) {
2209                         $clauses = []; // list WHERE clauses that each identify a single row
2210                         foreach ( $rows as $row ) {
2211                                 foreach ( $uniqueIndexes as $index ) {
2212                                         $index = is_array( $index ) ? $index : [ $index ]; // columns
2213                                         $rowKey = []; // unique key to this row
2214                                         foreach ( $index as $column ) {
2215                                                 $rowKey[$column] = $row[$column];
2216                                         }
2217                                         $clauses[] = $this->makeList( $rowKey, self::LIST_AND );
2218                                 }
2219                         }
2220                         $where = [ $this->makeList( $clauses, self::LIST_OR ) ];
2221                 } else {
2222                         $where = false;
2223                 }
2224
2225                 $useTrx = !$this->mTrxLevel;
2226                 if ( $useTrx ) {
2227                         $this->begin( $fname, self::TRANSACTION_INTERNAL );
2228                 }
2229                 try {
2230                         # Update any existing conflicting row(s)
2231                         if ( $where !== false ) {
2232                                 $ok = $this->update( $table, $set, $where, $fname );
2233                         } else {
2234                                 $ok = true;
2235                         }
2236                         # Now insert any non-conflicting row(s)
2237                         $ok = $this->insert( $table, $rows, $fname, [ 'IGNORE' ] ) && $ok;
2238                 } catch ( Exception $e ) {
2239                         if ( $useTrx ) {
2240                                 $this->rollback( $fname, self::FLUSHING_INTERNAL );
2241                         }
2242                         throw $e;
2243                 }
2244                 if ( $useTrx ) {
2245                         $this->commit( $fname, self::FLUSHING_INTERNAL );
2246                 }
2247
2248                 return $ok;
2249         }
2250
2251         public function deleteJoin( $delTable, $joinTable, $delVar, $joinVar, $conds,
2252                 $fname = __METHOD__
2253         ) {
2254                 if ( !$conds ) {
2255                         throw new DBUnexpectedError( $this, __METHOD__ . ' called with empty $conds' );
2256                 }
2257
2258                 $delTable = $this->tableName( $delTable );
2259                 $joinTable = $this->tableName( $joinTable );
2260                 $sql = "DELETE FROM $delTable WHERE $delVar IN (SELECT $joinVar FROM $joinTable ";
2261                 if ( $conds != '*' ) {
2262                         $sql .= 'WHERE ' . $this->makeList( $conds, self::LIST_AND );
2263                 }
2264                 $sql .= ')';
2265
2266                 $this->query( $sql, $fname );
2267         }
2268
2269         /**
2270          * Returns the size of a text field, or -1 for "unlimited"
2271          *
2272          * @param string $table
2273          * @param string $field
2274          * @return int
2275          */
2276         public function textFieldSize( $table, $field ) {
2277                 $table = $this->tableName( $table );
2278                 $sql = "SHOW COLUMNS FROM $table LIKE \"$field\";";
2279                 $res = $this->query( $sql, __METHOD__ );
2280                 $row = $this->fetchObject( $res );
2281
2282                 $m = [];
2283
2284                 if ( preg_match( '/\((.*)\)/', $row->Type, $m ) ) {
2285                         $size = $m[1];
2286                 } else {
2287                         $size = -1;
2288                 }
2289
2290                 return $size;
2291         }
2292
2293         public function delete( $table, $conds, $fname = __METHOD__ ) {
2294                 if ( !$conds ) {
2295                         throw new DBUnexpectedError( $this, __METHOD__ . ' called with no conditions' );
2296                 }
2297
2298                 $table = $this->tableName( $table );
2299                 $sql = "DELETE FROM $table";
2300
2301                 if ( $conds != '*' ) {
2302                         if ( is_array( $conds ) ) {
2303                                 $conds = $this->makeList( $conds, self::LIST_AND );
2304                         }
2305                         $sql .= ' WHERE ' . $conds;
2306                 }
2307
2308                 return $this->query( $sql, $fname );
2309         }
2310
2311         public function insertSelect(
2312                 $destTable, $srcTable, $varMap, $conds,
2313                 $fname = __METHOD__, $insertOptions = [], $selectOptions = []
2314         ) {
2315                 if ( $this->cliMode ) {
2316                         // For massive migrations with downtime, we don't want to select everything
2317                         // into memory and OOM, so do all this native on the server side if possible.
2318                         return $this->nativeInsertSelect(
2319                                 $destTable,
2320                                 $srcTable,
2321                                 $varMap,
2322                                 $conds,
2323                                 $fname,
2324                                 $insertOptions,
2325                                 $selectOptions
2326                         );
2327                 }
2328
2329                 // For web requests, do a locking SELECT and then INSERT. This puts the SELECT burden
2330                 // on only the master (without needing row-based-replication). It also makes it easy to
2331                 // know how big the INSERT is going to be.
2332                 $fields = [];
2333                 foreach ( $varMap as $dstColumn => $sourceColumnOrSql ) {
2334                         $fields[] = $this->fieldNameWithAlias( $sourceColumnOrSql, $dstColumn );
2335                 }
2336                 $selectOptions[] = 'FOR UPDATE';
2337                 $res = $this->select( $srcTable, implode( ',', $fields ), $conds, $fname, $selectOptions );
2338                 if ( !$res ) {
2339                         return false;
2340                 }
2341
2342                 $rows = [];
2343                 foreach ( $res as $row ) {
2344                         $rows[] = (array)$row;
2345                 }
2346
2347                 return $this->insert( $destTable, $rows, $fname, $insertOptions );
2348         }
2349
2350         public function nativeInsertSelect( $destTable, $srcTable, $varMap, $conds,
2351                 $fname = __METHOD__,
2352                 $insertOptions = [], $selectOptions = []
2353         ) {
2354                 $destTable = $this->tableName( $destTable );
2355
2356                 if ( !is_array( $insertOptions ) ) {
2357                         $insertOptions = [ $insertOptions ];
2358                 }
2359
2360                 $insertOptions = $this->makeInsertOptions( $insertOptions );
2361
2362                 if ( !is_array( $selectOptions ) ) {
2363                         $selectOptions = [ $selectOptions ];
2364                 }
2365
2366                 list( $startOpts, $useIndex, $tailOpts, $ignoreIndex ) = $this->makeSelectOptions(
2367                         $selectOptions );
2368
2369                 if ( is_array( $srcTable ) ) {
2370                         $srcTable = implode( ',', array_map( [ &$this, 'tableName' ], $srcTable ) );
2371                 } else {
2372                         $srcTable = $this->tableName( $srcTable );
2373                 }
2374
2375                 $sql = "INSERT $insertOptions INTO $destTable (" . implode( ',', array_keys( $varMap ) ) . ')' .
2376                         " SELECT $startOpts " . implode( ',', $varMap ) .
2377                         " FROM $srcTable $useIndex $ignoreIndex ";
2378
2379                 if ( $conds != '*' ) {
2380                         if ( is_array( $conds ) ) {
2381                                 $conds = $this->makeList( $conds, self::LIST_AND );
2382                         }
2383                         $sql .= " WHERE $conds";
2384                 }
2385
2386                 $sql .= " $tailOpts";
2387
2388                 return $this->query( $sql, $fname );
2389         }
2390
2391         /**
2392          * Construct a LIMIT query with optional offset. This is used for query
2393          * pages. The SQL should be adjusted so that only the first $limit rows
2394          * are returned. If $offset is provided as well, then the first $offset
2395          * rows should be discarded, and the next $limit rows should be returned.
2396          * If the result of the query is not ordered, then the rows to be returned
2397          * are theoretically arbitrary.
2398          *
2399          * $sql is expected to be a SELECT, if that makes a difference.
2400          *
2401          * The version provided by default works in MySQL and SQLite. It will very
2402          * likely need to be overridden for most other DBMSes.
2403          *
2404          * @param string $sql SQL query we will append the limit too
2405          * @param int $limit The SQL limit
2406          * @param int|bool $offset The SQL offset (default false)
2407          * @throws DBUnexpectedError
2408          * @return string
2409          */
2410         public function limitResult( $sql, $limit, $offset = false ) {
2411                 if ( !is_numeric( $limit ) ) {
2412                         throw new DBUnexpectedError( $this, "Invalid non-numeric limit passed to limitResult()\n" );
2413                 }
2414
2415                 return "$sql LIMIT "
2416                 . ( ( is_numeric( $offset ) && $offset != 0 ) ? "{$offset}," : "" )
2417                 . "{$limit} ";
2418         }
2419
2420         public function unionSupportsOrderAndLimit() {
2421                 return true; // True for almost every DB supported
2422         }
2423
2424         public function unionQueries( $sqls, $all ) {
2425                 $glue = $all ? ') UNION ALL (' : ') UNION (';
2426
2427                 return '(' . implode( $glue, $sqls ) . ')';
2428         }
2429
2430         public function conditional( $cond, $trueVal, $falseVal ) {
2431                 if ( is_array( $cond ) ) {
2432                         $cond = $this->makeList( $cond, self::LIST_AND );
2433                 }
2434
2435                 return " (CASE WHEN $cond THEN $trueVal ELSE $falseVal END) ";
2436         }
2437
2438         public function strreplace( $orig, $old, $new ) {
2439                 return "REPLACE({$orig}, {$old}, {$new})";
2440         }
2441
2442         public function getServerUptime() {
2443                 return 0;
2444         }
2445
2446         public function wasDeadlock() {
2447                 return false;
2448         }
2449
2450         public function wasLockTimeout() {
2451                 return false;
2452         }
2453
2454         public function wasErrorReissuable() {
2455                 return false;
2456         }
2457
2458         public function wasReadOnlyError() {
2459                 return false;
2460         }
2461
2462         /**
2463          * Determines if the given query error was a connection drop
2464          * STUB
2465          *
2466          * @param integer|string $errno
2467          * @return bool
2468          */
2469         public function wasConnectionError( $errno ) {
2470                 return false;
2471         }
2472
2473         /**
2474          * Perform a deadlock-prone transaction.
2475          *
2476          * This function invokes a callback function to perform a set of write
2477          * queries. If a deadlock occurs during the processing, the transaction
2478          * will be rolled back and the callback function will be called again.
2479          *
2480          * Avoid using this method outside of Job or Maintenance classes.
2481          *
2482          * Usage:
2483          *   $dbw->deadlockLoop( callback, ... );
2484          *
2485          * Extra arguments are passed through to the specified callback function.
2486          * This method requires that no transactions are already active to avoid
2487          * causing premature commits or exceptions.
2488          *
2489          * Returns whatever the callback function returned on its successful,
2490          * iteration, or false on error, for example if the retry limit was
2491          * reached.
2492          *
2493          * @return mixed
2494          * @throws DBUnexpectedError
2495          * @throws Exception
2496          */
2497         public function deadlockLoop() {
2498                 $args = func_get_args();
2499                 $function = array_shift( $args );
2500                 $tries = self::DEADLOCK_TRIES;
2501
2502                 $this->begin( __METHOD__ );
2503
2504                 $retVal = null;
2505                 /** @var Exception $e */
2506                 $e = null;
2507                 do {
2508                         try {
2509                                 $retVal = call_user_func_array( $function, $args );
2510                                 break;
2511                         } catch ( DBQueryError $e ) {
2512                                 if ( $this->wasDeadlock() ) {
2513                                         // Retry after a randomized delay
2514                                         usleep( mt_rand( self::DEADLOCK_DELAY_MIN, self::DEADLOCK_DELAY_MAX ) );
2515                                 } else {
2516                                         // Throw the error back up
2517                                         throw $e;
2518                                 }
2519                         }
2520                 } while ( --$tries > 0 );
2521
2522                 if ( $tries <= 0 ) {
2523                         // Too many deadlocks; give up
2524                         $this->rollback( __METHOD__ );
2525                         throw $e;
2526                 } else {
2527                         $this->commit( __METHOD__ );
2528
2529                         return $retVal;
2530                 }
2531         }
2532
2533         public function masterPosWait( DBMasterPos $pos, $timeout ) {
2534                 # Real waits are implemented in the subclass.
2535                 return 0;
2536         }
2537
2538         public function getSlavePos() {
2539                 # Stub
2540                 return false;
2541         }
2542
2543         public function getMasterPos() {
2544                 # Stub
2545                 return false;
2546         }
2547
2548         public function serverIsReadOnly() {
2549                 return false;
2550         }
2551
2552         final public function onTransactionResolution( callable $callback, $fname = __METHOD__ ) {
2553                 if ( !$this->mTrxLevel ) {
2554                         throw new DBUnexpectedError( $this, "No transaction is active." );
2555                 }
2556                 $this->mTrxEndCallbacks[] = [ $callback, $fname ];
2557         }
2558
2559         final public function onTransactionIdle( callable $callback, $fname = __METHOD__ ) {
2560                 $this->mTrxIdleCallbacks[] = [ $callback, $fname ];
2561                 if ( !$this->mTrxLevel ) {
2562                         $this->runOnTransactionIdleCallbacks( self::TRIGGER_IDLE );
2563                 }
2564         }
2565
2566         final public function onTransactionPreCommitOrIdle( callable $callback, $fname = __METHOD__ ) {
2567                 if ( $this->mTrxLevel ) {
2568                         $this->mTrxPreCommitCallbacks[] = [ $callback, $fname ];
2569                 } else {
2570                         // If no transaction is active, then make one for this callback
2571                         $this->startAtomic( __METHOD__ );
2572                         try {
2573                                 call_user_func( $callback );
2574                                 $this->endAtomic( __METHOD__ );
2575                         } catch ( Exception $e ) {
2576                                 $this->rollback( __METHOD__, self::FLUSHING_INTERNAL );
2577                                 throw $e;
2578                         }
2579                 }
2580         }
2581
2582         final public function setTransactionListener( $name, callable $callback = null ) {
2583                 if ( $callback ) {
2584                         $this->mTrxRecurringCallbacks[$name] = $callback;
2585                 } else {
2586                         unset( $this->mTrxRecurringCallbacks[$name] );
2587                 }
2588         }
2589
2590         /**
2591          * Whether to disable running of post-COMMIT/ROLLBACK callbacks
2592          *
2593          * This method should not be used outside of Database/LoadBalancer
2594          *
2595          * @param bool $suppress
2596          * @since 1.28
2597          */
2598         final public function setTrxEndCallbackSuppression( $suppress ) {
2599                 $this->mTrxEndCallbacksSuppressed = $suppress;
2600         }
2601
2602         /**
2603          * Actually run and consume any "on transaction idle/resolution" callbacks.
2604          *
2605          * This method should not be used outside of Database/LoadBalancer
2606          *
2607          * @param integer $trigger IDatabase::TRIGGER_* constant
2608          * @since 1.20
2609          * @throws Exception
2610          */
2611         public function runOnTransactionIdleCallbacks( $trigger ) {
2612                 if ( $this->mTrxEndCallbacksSuppressed ) {
2613                         return;
2614                 }
2615
2616                 $autoTrx = $this->getFlag( DBO_TRX ); // automatic begin() enabled?
2617                 /** @var Exception $e */
2618                 $e = null; // first exception
2619                 do { // callbacks may add callbacks :)
2620                         $callbacks = array_merge(
2621                                 $this->mTrxIdleCallbacks,
2622                                 $this->mTrxEndCallbacks // include "transaction resolution" callbacks
2623                         );
2624                         $this->mTrxIdleCallbacks = []; // consumed (and recursion guard)
2625                         $this->mTrxEndCallbacks = []; // consumed (recursion guard)
2626                         foreach ( $callbacks as $callback ) {
2627                                 try {
2628                                         list( $phpCallback ) = $callback;
2629                                         $this->clearFlag( DBO_TRX ); // make each query its own transaction
2630                                         call_user_func_array( $phpCallback, [ $trigger ] );
2631                                         if ( $autoTrx ) {
2632                                                 $this->setFlag( DBO_TRX ); // restore automatic begin()
2633                                         } else {
2634                                                 $this->clearFlag( DBO_TRX ); // restore auto-commit
2635                                         }
2636                                 } catch ( Exception $ex ) {
2637                                         call_user_func( $this->errorLogger, $ex );
2638                                         $e = $e ?: $ex;
2639                                         // Some callbacks may use startAtomic/endAtomic, so make sure
2640                                         // their transactions are ended so other callbacks don't fail
2641                                         if ( $this->trxLevel() ) {
2642                                                 $this->rollback( __METHOD__, self::FLUSHING_INTERNAL );
2643                                         }
2644                                 }
2645                         }
2646                 } while ( count( $this->mTrxIdleCallbacks ) );
2647
2648                 if ( $e instanceof Exception ) {
2649                         throw $e; // re-throw any first exception
2650                 }
2651         }
2652
2653         /**
2654          * Actually run and consume any "on transaction pre-commit" callbacks.
2655          *
2656          * This method should not be used outside of Database/LoadBalancer
2657          *
2658          * @since 1.22
2659          * @throws Exception
2660          */
2661         public function runOnTransactionPreCommitCallbacks() {
2662                 $e = null; // first exception
2663                 do { // callbacks may add callbacks :)
2664                         $callbacks = $this->mTrxPreCommitCallbacks;
2665                         $this->mTrxPreCommitCallbacks = []; // consumed (and recursion guard)
2666                         foreach ( $callbacks as $callback ) {
2667                                 try {
2668                                         list( $phpCallback ) = $callback;
2669                                         call_user_func( $phpCallback );
2670                                 } catch ( Exception $ex ) {
2671                                         call_user_func( $this->errorLogger, $ex );
2672                                         $e = $e ?: $ex;
2673                                 }
2674                         }
2675                 } while ( count( $this->mTrxPreCommitCallbacks ) );
2676
2677                 if ( $e instanceof Exception ) {
2678                         throw $e; // re-throw any first exception
2679                 }
2680         }
2681
2682         /**
2683          * Actually run any "transaction listener" callbacks.
2684          *
2685          * This method should not be used outside of Database/LoadBalancer
2686          *
2687          * @param integer $trigger IDatabase::TRIGGER_* constant
2688          * @throws Exception
2689          * @since 1.20
2690          */
2691         public function runTransactionListenerCallbacks( $trigger ) {
2692                 if ( $this->mTrxEndCallbacksSuppressed ) {
2693                         return;
2694                 }
2695
2696                 /** @var Exception $e */
2697                 $e = null; // first exception
2698
2699                 foreach ( $this->mTrxRecurringCallbacks as $phpCallback ) {
2700                         try {
2701                                 $phpCallback( $trigger, $this );
2702                         } catch ( Exception $ex ) {
2703                                 call_user_func( $this->errorLogger, $ex );
2704                                 $e = $e ?: $ex;
2705                         }
2706                 }
2707
2708                 if ( $e instanceof Exception ) {
2709                         throw $e; // re-throw any first exception
2710                 }
2711         }
2712
2713         final public function startAtomic( $fname = __METHOD__ ) {
2714                 if ( !$this->mTrxLevel ) {
2715                         $this->begin( $fname, self::TRANSACTION_INTERNAL );
2716                         // If DBO_TRX is set, a series of startAtomic/endAtomic pairs will result
2717                         // in all changes being in one transaction to keep requests transactional.
2718                         if ( !$this->getFlag( DBO_TRX ) ) {
2719                                 $this->mTrxAutomaticAtomic = true;
2720                         }
2721                 }
2722
2723                 $this->mTrxAtomicLevels[] = $fname;
2724         }
2725
2726         final public function endAtomic( $fname = __METHOD__ ) {
2727                 if ( !$this->mTrxLevel ) {
2728                         throw new DBUnexpectedError( $this, "No atomic transaction is open (got $fname)." );
2729                 }
2730                 if ( !$this->mTrxAtomicLevels ||
2731                         array_pop( $this->mTrxAtomicLevels ) !== $fname
2732                 ) {
2733                         throw new DBUnexpectedError( $this, "Invalid atomic section ended (got $fname)." );
2734                 }
2735
2736                 if ( !$this->mTrxAtomicLevels && $this->mTrxAutomaticAtomic ) {
2737                         $this->commit( $fname, self::FLUSHING_INTERNAL );
2738                 }
2739         }
2740
2741         final public function doAtomicSection( $fname, callable $callback ) {
2742                 $this->startAtomic( $fname );
2743                 try {
2744                         $res = call_user_func_array( $callback, [ $this, $fname ] );
2745                 } catch ( Exception $e ) {
2746                         $this->rollback( $fname, self::FLUSHING_INTERNAL );
2747                         throw $e;
2748                 }
2749                 $this->endAtomic( $fname );
2750
2751                 return $res;
2752         }
2753
2754         final public function begin( $fname = __METHOD__, $mode = self::TRANSACTION_EXPLICIT ) {
2755                 // Protect against mismatched atomic section, transaction nesting, and snapshot loss
2756                 if ( $this->mTrxLevel ) {
2757                         if ( $this->mTrxAtomicLevels ) {
2758                                 $levels = implode( ', ', $this->mTrxAtomicLevels );
2759                                 $msg = "$fname: Got explicit BEGIN while atomic section(s) $levels are open.";
2760                                 throw new DBUnexpectedError( $this, $msg );
2761                         } elseif ( !$this->mTrxAutomatic ) {
2762                                 $msg = "$fname: Explicit transaction already active (from {$this->mTrxFname}).";
2763                                 throw new DBUnexpectedError( $this, $msg );
2764                         } else {
2765                                 // @TODO: make this an exception at some point
2766                                 $msg = "$fname: Implicit transaction already active (from {$this->mTrxFname}).";
2767                                 $this->queryLogger->error( $msg );
2768                                 return; // join the main transaction set
2769                         }
2770                 } elseif ( $this->getFlag( DBO_TRX ) && $mode !== self::TRANSACTION_INTERNAL ) {
2771                         // @TODO: make this an exception at some point
2772                         $msg = "$fname: Implicit transaction expected (DBO_TRX set).";
2773                         $this->queryLogger->error( $msg );
2774                         return; // let any writes be in the main transaction
2775                 }
2776
2777                 // Avoid fatals if close() was called
2778                 $this->assertOpen();
2779
2780                 $this->doBegin( $fname );
2781                 $this->mTrxTimestamp = microtime( true );
2782                 $this->mTrxFname = $fname;
2783                 $this->mTrxDoneWrites = false;
2784                 $this->mTrxAutomatic = ( $mode === self::TRANSACTION_INTERNAL );
2785                 $this->mTrxAutomaticAtomic = false;
2786                 $this->mTrxAtomicLevels = [];
2787                 $this->mTrxShortId = sprintf( '%06x', mt_rand( 0, 0xffffff ) );
2788                 $this->mTrxWriteDuration = 0.0;
2789                 $this->mTrxWriteQueryCount = 0;
2790                 $this->mTrxWriteAdjDuration = 0.0;
2791                 $this->mTrxWriteAdjQueryCount = 0;
2792                 $this->mTrxWriteCallers = [];
2793                 // First SELECT after BEGIN will establish the snapshot in REPEATABLE-READ.
2794                 // Get an estimate of the replica DB lag before then, treating estimate staleness
2795                 // as lag itself just to be safe
2796                 $status = $this->getApproximateLagStatus();
2797                 $this->mTrxReplicaLag = $status['lag'] + ( microtime( true ) - $status['since'] );
2798         }
2799
2800         /**
2801          * Issues the BEGIN command to the database server.
2802          *
2803          * @see DatabaseBase::begin()
2804          * @param string $fname
2805          */
2806         protected function doBegin( $fname ) {
2807                 $this->query( 'BEGIN', $fname );
2808                 $this->mTrxLevel = 1;
2809         }
2810
2811         final public function commit( $fname = __METHOD__, $flush = '' ) {
2812                 if ( $this->mTrxLevel && $this->mTrxAtomicLevels ) {
2813                         // There are still atomic sections open. This cannot be ignored
2814                         $levels = implode( ', ', $this->mTrxAtomicLevels );
2815                         throw new DBUnexpectedError(
2816                                 $this,
2817                                 "$fname: Got COMMIT while atomic sections $levels are still open."
2818                         );
2819                 }
2820
2821                 if ( $flush === self::FLUSHING_INTERNAL || $flush === self::FLUSHING_ALL_PEERS ) {
2822                         if ( !$this->mTrxLevel ) {
2823                                 return; // nothing to do
2824                         } elseif ( !$this->mTrxAutomatic ) {
2825                                 throw new DBUnexpectedError(
2826                                         $this,
2827                                         "$fname: Flushing an explicit transaction, getting out of sync."
2828                                 );
2829                         }
2830                 } else {
2831                         if ( !$this->mTrxLevel ) {
2832                                 $this->queryLogger->error( "$fname: No transaction to commit, something got out of sync." );
2833                                 return; // nothing to do
2834                         } elseif ( $this->mTrxAutomatic ) {
2835                                 // @TODO: make this an exception at some point
2836                                 $msg = "$fname: Explicit commit of implicit transaction.";
2837                                 $this->queryLogger->error( $msg );
2838                                 return; // wait for the main transaction set commit round
2839                         }
2840                 }
2841
2842                 // Avoid fatals if close() was called
2843                 $this->assertOpen();
2844
2845                 $this->runOnTransactionPreCommitCallbacks();
2846                 $writeTime = $this->pendingWriteQueryDuration( self::ESTIMATE_DB_APPLY );
2847                 $this->doCommit( $fname );
2848                 if ( $this->mTrxDoneWrites ) {
2849                         $this->mDoneWrites = microtime( true );
2850                         $this->trxProfiler->transactionWritingOut(
2851                                 $this->mServer, $this->mDBname, $this->mTrxShortId, $writeTime );
2852                 }
2853
2854                 $this->runOnTransactionIdleCallbacks( self::TRIGGER_COMMIT );
2855                 $this->runTransactionListenerCallbacks( self::TRIGGER_COMMIT );
2856         }
2857
2858         /**
2859          * Issues the COMMIT command to the database server.
2860          *
2861          * @see DatabaseBase::commit()
2862          * @param string $fname
2863          */
2864         protected function doCommit( $fname ) {
2865                 if ( $this->mTrxLevel ) {
2866                         $this->query( 'COMMIT', $fname );
2867                         $this->mTrxLevel = 0;
2868                 }
2869         }
2870
2871         final public function rollback( $fname = __METHOD__, $flush = '' ) {
2872                 if ( $flush === self::FLUSHING_INTERNAL || $flush === self::FLUSHING_ALL_PEERS ) {
2873                         if ( !$this->mTrxLevel ) {
2874                                 return; // nothing to do
2875                         }
2876                 } else {
2877                         if ( !$this->mTrxLevel ) {
2878                                 $this->queryLogger->error(
2879                                         "$fname: No transaction to rollback, something got out of sync." );
2880                                 return; // nothing to do
2881                         } elseif ( $this->getFlag( DBO_TRX ) ) {
2882                                 throw new DBUnexpectedError(
2883                                         $this,
2884                                         "$fname: Expected mass rollback of all peer databases (DBO_TRX set)."
2885                                 );
2886                         }
2887                 }
2888
2889                 // Avoid fatals if close() was called
2890                 $this->assertOpen();
2891
2892                 $this->doRollback( $fname );
2893                 $this->mTrxAtomicLevels = [];
2894                 if ( $this->mTrxDoneWrites ) {
2895                         $this->trxProfiler->transactionWritingOut(
2896                                 $this->mServer, $this->mDBname, $this->mTrxShortId );
2897                 }
2898
2899                 $this->mTrxIdleCallbacks = []; // clear
2900                 $this->mTrxPreCommitCallbacks = []; // clear
2901                 $this->runOnTransactionIdleCallbacks( self::TRIGGER_ROLLBACK );
2902                 $this->runTransactionListenerCallbacks( self::TRIGGER_ROLLBACK );
2903         }
2904
2905         /**
2906          * Issues the ROLLBACK command to the database server.
2907          *
2908          * @see DatabaseBase::rollback()
2909          * @param string $fname
2910          */
2911         protected function doRollback( $fname ) {
2912                 if ( $this->mTrxLevel ) {
2913                         # Disconnects cause rollback anyway, so ignore those errors
2914                         $ignoreErrors = true;
2915                         $this->query( 'ROLLBACK', $fname, $ignoreErrors );
2916                         $this->mTrxLevel = 0;
2917                 }
2918         }
2919
2920         public function flushSnapshot( $fname = __METHOD__ ) {
2921                 if ( $this->writesOrCallbacksPending() || $this->explicitTrxActive() ) {
2922                         // This only flushes transactions to clear snapshots, not to write data
2923                         $fnames = implode( ', ', $this->pendingWriteAndCallbackCallers() );
2924                         throw new DBUnexpectedError(
2925                                 $this,
2926                                 "$fname: Cannot COMMIT to clear snapshot because writes are pending ($fnames)."
2927                         );
2928                 }
2929
2930                 $this->commit( $fname, self::FLUSHING_INTERNAL );
2931         }
2932
2933         public function explicitTrxActive() {
2934                 return $this->mTrxLevel && ( $this->mTrxAtomicLevels || !$this->mTrxAutomatic );
2935         }
2936
2937         /**
2938          * Creates a new table with structure copied from existing table
2939          * Note that unlike most database abstraction functions, this function does not
2940          * automatically append database prefix, because it works at a lower
2941          * abstraction level.
2942          * The table names passed to this function shall not be quoted (this
2943          * function calls addIdentifierQuotes when needed).
2944          *
2945          * @param string $oldName Name of table whose structure should be copied
2946          * @param string $newName Name of table to be created
2947          * @param bool $temporary Whether the new table should be temporary
2948          * @param string $fname Calling function name
2949          * @throws RuntimeException
2950          * @return bool True if operation was successful
2951          */
2952         public function duplicateTableStructure( $oldName, $newName, $temporary = false,
2953                 $fname = __METHOD__
2954         ) {
2955                 throw new RuntimeException( __METHOD__ . ' is not implemented in descendant class' );
2956         }
2957
2958         function listTables( $prefix = null, $fname = __METHOD__ ) {
2959                 throw new RuntimeException( __METHOD__ . ' is not implemented in descendant class' );
2960         }
2961
2962         /**
2963          * Reset the views process cache set by listViews()
2964          * @since 1.22
2965          */
2966         final public function clearViewsCache() {
2967                 $this->allViews = null;
2968         }
2969
2970         /**
2971          * Lists all the VIEWs in the database
2972          *
2973          * For caching purposes the list of all views should be stored in
2974          * $this->allViews. The process cache can be cleared with clearViewsCache()
2975          *
2976          * @param string $prefix Only show VIEWs with this prefix, eg. unit_test_
2977          * @param string $fname Name of calling function
2978          * @throws RuntimeException
2979          * @return array
2980          * @since 1.22
2981          */
2982         public function listViews( $prefix = null, $fname = __METHOD__ ) {
2983                 throw new RuntimeException( __METHOD__ . ' is not implemented in descendant class' );
2984         }
2985
2986         /**
2987          * Differentiates between a TABLE and a VIEW
2988          *
2989          * @param string $name Name of the database-structure to test.
2990          * @throws RuntimeException
2991          * @return bool
2992          * @since 1.22
2993          */
2994         public function isView( $name ) {
2995                 throw new RuntimeException( __METHOD__ . ' is not implemented in descendant class' );
2996         }
2997
2998         public function timestamp( $ts = 0 ) {
2999                 $t = new ConvertableTimestamp( $ts );
3000                 // Let errors bubble up to avoid putting garbage in the DB
3001                 return $t->getTimestamp( TS_MW );
3002         }
3003
3004         public function timestampOrNull( $ts = null ) {
3005                 if ( is_null( $ts ) ) {
3006                         return null;
3007                 } else {
3008                         return $this->timestamp( $ts );
3009                 }
3010         }
3011
3012         /**
3013          * Take the result from a query, and wrap it in a ResultWrapper if
3014          * necessary. Boolean values are passed through as is, to indicate success
3015          * of write queries or failure.
3016          *
3017          * Once upon a time, DatabaseBase::query() returned a bare MySQL result
3018          * resource, and it was necessary to call this function to convert it to
3019          * a wrapper. Nowadays, raw database objects are never exposed to external
3020          * callers, so this is unnecessary in external code.
3021          *
3022          * @param bool|ResultWrapper|resource|object $result
3023          * @return bool|ResultWrapper
3024          */
3025         protected function resultObject( $result ) {
3026                 if ( !$result ) {
3027                         return false;
3028                 } elseif ( $result instanceof ResultWrapper ) {
3029                         return $result;
3030                 } elseif ( $result === true ) {
3031                         // Successful write query
3032                         return $result;
3033                 } else {
3034                         return new ResultWrapper( $this, $result );
3035                 }
3036         }
3037
3038         public function ping( &$rtt = null ) {
3039                 // Avoid hitting the server if it was hit recently
3040                 if ( $this->isOpen() && ( microtime( true ) - $this->lastPing ) < self::PING_TTL ) {
3041                         if ( !func_num_args() || $this->mRTTEstimate > 0 ) {
3042                                 $rtt = $this->mRTTEstimate;
3043                                 return true; // don't care about $rtt
3044                         }
3045                 }
3046
3047                 // This will reconnect if possible or return false if not
3048                 $this->clearFlag( DBO_TRX, self::REMEMBER_PRIOR );
3049                 $ok = ( $this->query( self::PING_QUERY, __METHOD__, true ) !== false );
3050                 $this->restoreFlags( self::RESTORE_PRIOR );
3051
3052                 if ( $ok ) {
3053                         $rtt = $this->mRTTEstimate;
3054                 }
3055
3056                 return $ok;
3057         }
3058
3059         /**
3060          * @return bool
3061          */
3062         protected function reconnect() {
3063                 $this->closeConnection();
3064                 $this->mOpened = false;
3065                 $this->mConn = false;
3066                 try {
3067                         $this->open( $this->mServer, $this->mUser, $this->mPassword, $this->mDBname );
3068                         $this->lastPing = microtime( true );
3069                         $ok = true;
3070                 } catch ( DBConnectionError $e ) {
3071                         $ok = false;
3072                 }
3073
3074                 return $ok;
3075         }
3076
3077         public function getSessionLagStatus() {
3078                 return $this->getTransactionLagStatus() ?: $this->getApproximateLagStatus();
3079         }
3080
3081         /**
3082          * Get the replica DB lag when the current transaction started
3083          *
3084          * This is useful when transactions might use snapshot isolation
3085          * (e.g. REPEATABLE-READ in innodb), so the "real" lag of that data
3086          * is this lag plus transaction duration. If they don't, it is still
3087          * safe to be pessimistic. This returns null if there is no transaction.
3088          *
3089          * @return array|null ('lag': seconds or false on error, 'since': UNIX timestamp of BEGIN)
3090          * @since 1.27
3091          */
3092         public function getTransactionLagStatus() {
3093                 return $this->mTrxLevel
3094                         ? [ 'lag' => $this->mTrxReplicaLag, 'since' => $this->trxTimestamp() ]
3095                         : null;
3096         }
3097
3098         /**
3099          * Get a replica DB lag estimate for this server
3100          *
3101          * @return array ('lag': seconds or false on error, 'since': UNIX timestamp of estimate)
3102          * @since 1.27
3103          */
3104         public function getApproximateLagStatus() {
3105                 return [
3106                         'lag'   => $this->getLBInfo( 'replica' ) ? $this->getLag() : 0,
3107                         'since' => microtime( true )
3108                 ];
3109         }
3110
3111         /**
3112          * Merge the result of getSessionLagStatus() for several DBs
3113          * using the most pessimistic values to estimate the lag of
3114          * any data derived from them in combination
3115          *
3116          * This is information is useful for caching modules
3117          *
3118          * @see WANObjectCache::set()
3119          * @see WANObjectCache::getWithSetCallback()
3120          *
3121          * @param IDatabase $db1
3122          * @param IDatabase ...
3123          * @return array Map of values:
3124          *   - lag: highest lag of any of the DBs or false on error (e.g. replication stopped)
3125          *   - since: oldest UNIX timestamp of any of the DB lag estimates
3126          *   - pending: whether any of the DBs have uncommitted changes
3127          * @since 1.27
3128          */
3129         public static function getCacheSetOptions( IDatabase $db1 ) {
3130                 $res = [ 'lag' => 0, 'since' => INF, 'pending' => false ];
3131                 foreach ( func_get_args() as $db ) {
3132                         /** @var IDatabase $db */
3133                         $status = $db->getSessionLagStatus();
3134                         if ( $status['lag'] === false ) {
3135                                 $res['lag'] = false;
3136                         } elseif ( $res['lag'] !== false ) {
3137                                 $res['lag'] = max( $res['lag'], $status['lag'] );
3138                         }
3139                         $res['since'] = min( $res['since'], $status['since'] );
3140                         $res['pending'] = $res['pending'] ?: $db->writesPending();
3141                 }
3142
3143                 return $res;
3144         }
3145
3146         public function getLag() {
3147                 return 0;
3148         }
3149
3150         function maxListLen() {
3151                 return 0;
3152         }
3153
3154         public function encodeBlob( $b ) {
3155                 return $b;
3156         }
3157
3158         public function decodeBlob( $b ) {
3159                 if ( $b instanceof Blob ) {
3160                         $b = $b->fetch();
3161                 }
3162                 return $b;
3163         }
3164
3165         public function setSessionOptions( array $options ) {
3166         }
3167
3168         /**
3169          * Read and execute SQL commands from a file.
3170          *
3171          * Returns true on success, error string or exception on failure (depending
3172          * on object's error ignore settings).
3173          *
3174          * @param string $filename File name to open
3175          * @param bool|callable $lineCallback Optional function called before reading each line
3176          * @param bool|callable $resultCallback Optional function called for each MySQL result
3177          * @param bool|string $fname Calling function name or false if name should be
3178          *   generated dynamically using $filename
3179          * @param bool|callable $inputCallback Optional function called for each
3180          *   complete line sent
3181          * @return bool|string
3182          * @throws Exception
3183          */
3184         public function sourceFile(
3185                 $filename, $lineCallback = false, $resultCallback = false, $fname = false, $inputCallback = false
3186         ) {
3187                 MediaWiki\suppressWarnings();
3188                 $fp = fopen( $filename, 'r' );
3189                 MediaWiki\restoreWarnings();
3190
3191                 if ( false === $fp ) {
3192                         throw new RuntimeException( "Could not open \"{$filename}\".\n" );
3193                 }
3194
3195                 if ( !$fname ) {
3196                         $fname = __METHOD__ . "( $filename )";
3197                 }
3198
3199                 try {
3200                         $error = $this->sourceStream( $fp, $lineCallback, $resultCallback, $fname, $inputCallback );
3201                 } catch ( Exception $e ) {
3202                         fclose( $fp );
3203                         throw $e;
3204                 }
3205
3206                 fclose( $fp );
3207
3208                 return $error;
3209         }
3210
3211         public function setSchemaVars( $vars ) {
3212                 $this->mSchemaVars = $vars;
3213         }
3214
3215         /**
3216          * Read and execute commands from an open file handle.
3217          *
3218          * Returns true on success, error string or exception on failure (depending
3219          * on object's error ignore settings).
3220          *
3221          * @param resource $fp File handle
3222          * @param bool|callable $lineCallback Optional function called before reading each query
3223          * @param bool|callable $resultCallback Optional function called for each MySQL result
3224          * @param string $fname Calling function name
3225          * @param bool|callable $inputCallback Optional function called for each complete query sent
3226          * @return bool|string
3227          */
3228         public function sourceStream( $fp, $lineCallback = false, $resultCallback = false,
3229                 $fname = __METHOD__, $inputCallback = false
3230         ) {
3231                 $cmd = '';
3232
3233                 while ( !feof( $fp ) ) {
3234                         if ( $lineCallback ) {
3235                                 call_user_func( $lineCallback );
3236                         }
3237
3238                         $line = trim( fgets( $fp ) );
3239
3240                         if ( $line == '' ) {
3241                                 continue;
3242                         }
3243
3244                         if ( '-' == $line[0] && '-' == $line[1] ) {
3245                                 continue;
3246                         }
3247
3248                         if ( $cmd != '' ) {
3249                                 $cmd .= ' ';
3250                         }
3251
3252                         $done = $this->streamStatementEnd( $cmd, $line );
3253
3254                         $cmd .= "$line\n";
3255
3256                         if ( $done || feof( $fp ) ) {
3257                                 $cmd = $this->replaceVars( $cmd );
3258
3259                                 if ( ( $inputCallback && call_user_func( $inputCallback, $cmd ) ) || !$inputCallback ) {
3260                                         $res = $this->query( $cmd, $fname );
3261
3262                                         if ( $resultCallback ) {
3263                                                 call_user_func( $resultCallback, $res, $this );
3264                                         }
3265
3266                                         if ( false === $res ) {
3267                                                 $err = $this->lastError();
3268
3269                                                 return "Query \"{$cmd}\" failed with error code \"$err\".\n";
3270                                         }
3271                                 }
3272                                 $cmd = '';
3273                         }
3274                 }
3275
3276                 return true;
3277         }
3278
3279         /**
3280          * Called by sourceStream() to check if we've reached a statement end
3281          *
3282          * @param string $sql SQL assembled so far
3283          * @param string $newLine New line about to be added to $sql
3284          * @return bool Whether $newLine contains end of the statement
3285          */
3286         public function streamStatementEnd( &$sql, &$newLine ) {
3287                 if ( $this->delimiter ) {
3288                         $prev = $newLine;
3289                         $newLine = preg_replace( '/' . preg_quote( $this->delimiter, '/' ) . '$/', '', $newLine );
3290                         if ( $newLine != $prev ) {
3291                                 return true;
3292                         }
3293                 }
3294
3295                 return false;
3296         }
3297
3298         /**
3299          * Database independent variable replacement. Replaces a set of variables
3300          * in an SQL statement with their contents as given by $this->getSchemaVars().
3301          *
3302          * Supports '{$var}' `{$var}` and / *$var* / (without the spaces) style variables.
3303          *
3304          * - '{$var}' should be used for text and is passed through the database's
3305          *   addQuotes method.
3306          * - `{$var}` should be used for identifiers (e.g. table and database names).
3307          *   It is passed through the database's addIdentifierQuotes method which
3308          *   can be overridden if the database uses something other than backticks.
3309          * - / *_* / or / *$wgDBprefix* / passes the name that follows through the
3310          *   database's tableName method.
3311          * - / *i* / passes the name that follows through the database's indexName method.
3312          * - In all other cases, / *$var* / is left unencoded. Except for table options,
3313          *   its use should be avoided. In 1.24 and older, string encoding was applied.
3314          *
3315          * @param string $ins SQL statement to replace variables in
3316          * @return string The new SQL statement with variables replaced
3317          */
3318         protected function replaceVars( $ins ) {
3319                 $vars = $this->getSchemaVars();
3320                 return preg_replace_callback(
3321                         '!
3322                                 /\* (\$wgDBprefix|[_i]) \*/ (\w*) | # 1-2. tableName, indexName
3323                                 \'\{\$ (\w+) }\'                  | # 3. addQuotes
3324                                 `\{\$ (\w+) }`                    | # 4. addIdentifierQuotes
3325                                 /\*\$ (\w+) \*/                     # 5. leave unencoded
3326                         !x',
3327                         function ( $m ) use ( $vars ) {
3328                                 // Note: Because of <https://bugs.php.net/bug.php?id=51881>,
3329                                 // check for both nonexistent keys *and* the empty string.
3330                                 if ( isset( $m[1] ) && $m[1] !== '' ) {
3331                                         if ( $m[1] === 'i' ) {
3332                                                 return $this->indexName( $m[2] );
3333                                         } else {
3334                                                 return $this->tableName( $m[2] );
3335                                         }
3336                                 } elseif ( isset( $m[3] ) && $m[3] !== '' && array_key_exists( $m[3], $vars ) ) {
3337                                         return $this->addQuotes( $vars[$m[3]] );
3338                                 } elseif ( isset( $m[4] ) && $m[4] !== '' && array_key_exists( $m[4], $vars ) ) {
3339                                         return $this->addIdentifierQuotes( $vars[$m[4]] );
3340                                 } elseif ( isset( $m[5] ) && $m[5] !== '' && array_key_exists( $m[5], $vars ) ) {
3341                                         return $vars[$m[5]];
3342                                 } else {
3343                                         return $m[0];
3344                                 }
3345                         },
3346                         $ins
3347                 );
3348         }
3349
3350         /**
3351          * Get schema variables. If none have been set via setSchemaVars(), then
3352          * use some defaults from the current object.
3353          *
3354          * @return array
3355          */
3356         protected function getSchemaVars() {
3357                 if ( $this->mSchemaVars ) {
3358                         return $this->mSchemaVars;
3359                 } else {
3360                         return $this->getDefaultSchemaVars();
3361                 }
3362         }
3363
3364         /**
3365          * Get schema variables to use if none have been set via setSchemaVars().
3366          *
3367          * Override this in derived classes to provide variables for tables.sql
3368          * and SQL patch files.
3369          *
3370          * @return array
3371          */
3372         protected function getDefaultSchemaVars() {
3373                 return [];
3374         }
3375
3376         public function lockIsFree( $lockName, $method ) {
3377                 return true;
3378         }
3379
3380         public function lock( $lockName, $method, $timeout = 5 ) {
3381                 $this->mNamedLocksHeld[$lockName] = 1;
3382
3383                 return true;
3384         }
3385
3386         public function unlock( $lockName, $method ) {
3387                 unset( $this->mNamedLocksHeld[$lockName] );
3388
3389                 return true;
3390         }
3391
3392         public function getScopedLockAndFlush( $lockKey, $fname, $timeout ) {
3393                 if ( $this->writesOrCallbacksPending() ) {
3394                         // This only flushes transactions to clear snapshots, not to write data
3395                         $fnames = implode( ', ', $this->pendingWriteAndCallbackCallers() );
3396                         throw new DBUnexpectedError(
3397                                 $this,
3398                                 "$fname: Cannot COMMIT to clear snapshot because writes are pending ($fnames)."
3399                         );
3400                 }
3401
3402                 if ( !$this->lock( $lockKey, $fname, $timeout ) ) {
3403                         return null;
3404                 }
3405
3406                 $unlocker = new ScopedCallback( function () use ( $lockKey, $fname ) {
3407                         if ( $this->trxLevel() ) {
3408                                 // There is a good chance an exception was thrown, causing any early return
3409                                 // from the caller. Let any error handler get a chance to issue rollback().
3410                                 // If there isn't one, let the error bubble up and trigger server-side rollback.
3411                                 $this->onTransactionResolution(
3412                                         function () use ( $lockKey, $fname ) {
3413                                                 $this->unlock( $lockKey, $fname );
3414                                         },
3415                                         $fname
3416                                 );
3417                         } else {
3418                                 $this->unlock( $lockKey, $fname );
3419                         }
3420                 } );
3421
3422                 $this->commit( $fname, self::FLUSHING_INTERNAL );
3423
3424                 return $unlocker;
3425         }
3426
3427         public function namedLocksEnqueue() {
3428                 return false;
3429         }
3430
3431         /**
3432          * Lock specific tables
3433          *
3434          * @param array $read Array of tables to lock for read access
3435          * @param array $write Array of tables to lock for write access
3436          * @param string $method Name of caller
3437          * @param bool $lowPriority Whether to indicate writes to be LOW PRIORITY
3438          * @return bool
3439          */
3440         public function lockTables( $read, $write, $method, $lowPriority = true ) {
3441                 return true;
3442         }
3443
3444         /**
3445          * Unlock specific tables
3446          *
3447          * @param string $method The caller
3448          * @return bool
3449          */
3450         public function unlockTables( $method ) {
3451                 return true;
3452         }
3453
3454         /**
3455          * Delete a table
3456          * @param string $tableName
3457          * @param string $fName
3458          * @return bool|ResultWrapper
3459          * @since 1.18
3460          */
3461         public function dropTable( $tableName, $fName = __METHOD__ ) {
3462                 if ( !$this->tableExists( $tableName, $fName ) ) {
3463                         return false;
3464                 }
3465                 $sql = "DROP TABLE " . $this->tableName( $tableName ) . " CASCADE";
3466
3467                 return $this->query( $sql, $fName );
3468         }
3469
3470         public function getInfinity() {
3471                 return 'infinity';
3472         }
3473
3474         public function encodeExpiry( $expiry ) {
3475                 return ( $expiry == '' || $expiry == 'infinity' || $expiry == $this->getInfinity() )
3476                         ? $this->getInfinity()
3477                         : $this->timestamp( $expiry );
3478         }
3479
3480         public function decodeExpiry( $expiry, $format = TS_MW ) {
3481                 if ( $expiry == '' || $expiry == 'infinity' || $expiry == $this->getInfinity() ) {
3482                         return 'infinity';
3483                 }
3484
3485                 try {
3486                         $t = new ConvertableTimestamp( $expiry );
3487
3488                         return $t->getTimestamp( $format );
3489                 } catch ( TimestampException $e ) {
3490                         return false;
3491                 }
3492         }
3493
3494         public function setBigSelects( $value = true ) {
3495                 // no-op
3496         }
3497
3498         public function isReadOnly() {
3499                 return ( $this->getReadOnlyReason() !== false );
3500         }
3501
3502         /**
3503          * @return string|bool Reason this DB is read-only or false if it is not
3504          */
3505         protected function getReadOnlyReason() {
3506                 $reason = $this->getLBInfo( 'readOnlyReason' );
3507
3508                 return is_string( $reason ) ? $reason : false;
3509         }
3510
3511         public function setTableAliases( array $aliases ) {
3512                 $this->tableAliases = $aliases;
3513         }
3514
3515         /**
3516          * @return bool Whether a DB user is required to access the DB
3517          * @since 1.28
3518          */
3519         protected function requiresDatabaseUser() {
3520                 return true;
3521         }
3522
3523         /**
3524          * @since 1.19
3525          * @return string
3526          */
3527         public function __toString() {
3528                 return (string)$this->mConn;
3529         }
3530
3531         /**
3532          * Make sure that copies do not share the same client binding handle
3533          * @throws DBConnectionError
3534          */
3535         public function __clone() {
3536                 $this->connLogger->warning(
3537                         "Cloning " . get_class( $this ) . " is not recomended; forking connection:\n" .
3538                         ( new RuntimeException() )->getTraceAsString()
3539                 );
3540
3541                 if ( $this->isOpen() ) {
3542                         // Open a new connection resource without messing with the old one
3543                         $this->mOpened = false;
3544                         $this->mConn = false;
3545                         $this->mTrxLevel = 0; // no trx anymore
3546                         $this->open( $this->mServer, $this->mUser, $this->mPassword, $this->mDBname );
3547                         $this->lastPing = microtime( true );
3548                 }
3549         }
3550
3551         /**
3552          * Called by serialize. Throw an exception when DB connection is serialized.
3553          * This causes problems on some database engines because the connection is
3554          * not restored on unserialize.
3555          */
3556         public function __sleep() {
3557                 throw new RuntimeException( 'Database serialization may cause problems, since ' .
3558                         'the connection is not restored on wakeup.' );
3559         }
3560
3561         /**
3562          * Run a few simple sanity checks and close dangling connections
3563          */
3564         public function __destruct() {
3565                 if ( $this->mTrxLevel && $this->mTrxDoneWrites ) {
3566                         trigger_error( "Uncommitted DB writes (transaction from {$this->mTrxFname})." );
3567                 }
3568
3569                 $danglingWriters = $this->pendingWriteAndCallbackCallers();
3570                 if ( $danglingWriters ) {
3571                         $fnames = implode( ', ', $danglingWriters );
3572                         trigger_error( "DB transaction writes or callbacks still pending ($fnames)." );
3573                 }
3574
3575                 if ( $this->mConn ) {
3576                         // Avoid connection leaks for sanity
3577                         $this->closeConnection();
3578                         $this->mConn = false;
3579                         $this->mOpened = false;
3580                 }
3581         }
3582 }