includes/libs/rdbms/database/Database.php

   1 <?php
   2 /**
   3  * @defgroup Database Database
   4  *
   5  * This file deals with database interface functions
   6  * and query specifics/optimisations.
   7  *
   8  * This program is free software; you can redistribute it and/or modify
   9  * it under the terms of the GNU General Public License as published by
  10  * the Free Software Foundation; either version 2 of the License, or
  11  * (at your option) any later version.
  12  *
  13  * This program is distributed in the hope that it will be useful,
  14  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  15  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
  16  * GNU General Public License for more details.
  17  *
  18  * You should have received a copy of the GNU General Public License along
  19  * with this program; if not, write to the Free Software Foundation, Inc.,
  20  * 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
  21  * http://www.gnu.org/copyleft/gpl.html
  22  *
  23  * @file
  24  * @ingroup Database
  25  */
  26 use Psr\Log\LoggerAwareInterface;
  27 use Psr\Log\LoggerInterface;
  28
  29 /**
  30  * Database abstraction object
  31  * @ingroup Database
  32  */
  33 abstract class Database implements IDatabase, LoggerAwareInterface {
  34         /** Number of times to re-try an operation in case of deadlock */
  35         const DEADLOCK_TRIES = 4;
  36         /** Minimum time to wait before retry, in microseconds */
  37         const DEADLOCK_DELAY_MIN = 500000;
  38         /** Maximum time to wait before retry */
  39         const DEADLOCK_DELAY_MAX = 1500000;
  40
  41         /** How long before it is worth doing a dummy query to test the connection */
  42         const PING_TTL = 1.0;
  43         const PING_QUERY = 'SELECT 1 AS ping';
  44
  45         const TINY_WRITE_SEC = .010;
  46         const SLOW_WRITE_SEC = .500;
  47         const SMALL_WRITE_ROWS = 100;
  48
  49         /** @var string SQL query */
  50         protected $mLastQuery = '';
  51         /** @var bool */
  52         protected $mDoneWrites = false;
  53         /** @var string|bool */
  54         protected $mPHPError = false;
  55         /** @var string */
  56         protected $mServer;
  57         /** @var string */
  58         protected $mUser;
  59         /** @var string */
  60         protected $mPassword;
  61         /** @var string */
  62         protected $mDBname;
  63         /** @var array[] $aliases Map of (table => (dbname, schema, prefix) map) */
  64         protected $tableAliases = [];
  65         /** @var bool Whether this PHP instance is for a CLI script */
  66         protected $cliMode;
  67         /** @var string Agent name for query profiling */
  68         protected $agent;
  69
  70         /** @var BagOStuff APC cache */
  71         protected $srvCache;
  72         /** @var LoggerInterface */
  73         protected $connLogger;
  74         /** @var LoggerInterface */
  75         protected $queryLogger;
  76         /** @var callback Error logging callback */
  77         protected $errorLogger;
  78
  79         /** @var resource Database connection */
  80         protected $mConn = null;
  81         /** @var bool */
  82         protected $mOpened = false;
  83
  84         /** @var array[] List of (callable, method name) */
  85         protected $mTrxIdleCallbacks = [];
  86         /** @var array[] List of (callable, method name) */
  87         protected $mTrxPreCommitCallbacks = [];
  88         /** @var array[] List of (callable, method name) */
  89         protected $mTrxEndCallbacks = [];
  90         /** @var callable[] Map of (name => callable) */
  91         protected $mTrxRecurringCallbacks = [];
  92         /** @var bool Whether to suppress triggering of transaction end callbacks */
  93         protected $mTrxEndCallbacksSuppressed = false;
  94
  95         /** @var string */
  96         protected $mTablePrefix = '';
  97         /** @var string */
  98         protected $mSchema = '';
  99         /** @var integer */
 100         protected $mFlags;
 101         /** @var array */
 102         protected $mLBInfo = [];
 103         /** @var bool|null */
 104         protected $mDefaultBigSelects = null;
 105         /** @var array|bool */
 106         protected $mSchemaVars = false;
 107         /** @var array */
 108         protected $mSessionVars = [];
 109         /** @var array|null */
 110         protected $preparedArgs;
 111         /** @var string|bool|null Stashed value of html_errors INI setting */
 112         protected $htmlErrors;
 113         /** @var string */
 114         protected $delimiter = ';';
 115         /** @var DatabaseDomain */
 116         protected $currentDomain;
 117
 118         /**
 119          * Either 1 if a transaction is active or 0 otherwise.
 120          * The other Trx fields may not be meaningfull if this is 0.
 121          *
 122          * @var int
 123          */
 124         protected $mTrxLevel = 0;
 125         /**
 126          * Either a short hexidecimal string if a transaction is active or ""
 127          *
 128          * @var string
 129          * @see DatabaseBase::mTrxLevel
 130          */
 131         protected $mTrxShortId = '';
 132         /**
 133          * The UNIX time that the transaction started. Callers can assume that if
 134          * snapshot isolation is used, then the data is *at least* up to date to that
 135          * point (possibly more up-to-date since the first SELECT defines the snapshot).
 136          *
 137          * @var float|null
 138          * @see DatabaseBase::mTrxLevel
 139          */
 140         private $mTrxTimestamp = null;
 141         /** @var float Lag estimate at the time of BEGIN */
 142         private $mTrxReplicaLag = null;
 143         /**
 144          * Remembers the function name given for starting the most recent transaction via begin().
 145          * Used to provide additional context for error reporting.
 146          *
 147          * @var string
 148          * @see DatabaseBase::mTrxLevel
 149          */
 150         private $mTrxFname = null;
 151         /**
 152          * Record if possible write queries were done in the last transaction started
 153          *
 154          * @var bool
 155          * @see DatabaseBase::mTrxLevel
 156          */
 157         private $mTrxDoneWrites = false;
 158         /**
 159          * Record if the current transaction was started implicitly due to DBO_TRX being set.
 160          *
 161          * @var bool
 162          * @see DatabaseBase::mTrxLevel
 163          */
 164         private $mTrxAutomatic = false;
 165         /**
 166          * Array of levels of atomicity within transactions
 167          *
 168          * @var array
 169          */
 170         private $mTrxAtomicLevels = [];
 171         /**
 172          * Record if the current transaction was started implicitly by DatabaseBase::startAtomic
 173          *
 174          * @var bool
 175          */
 176         private $mTrxAutomaticAtomic = false;
 177         /**
 178          * Track the write query callers of the current transaction
 179          *
 180          * @var string[]
 181          */
 182         private $mTrxWriteCallers = [];
 183         /**
 184          * @var float Seconds spent in write queries for the current transaction
 185          */
 186         private $mTrxWriteDuration = 0.0;
 187         /**
 188          * @var integer Number of write queries for the current transaction
 189          */
 190         private $mTrxWriteQueryCount = 0;
 191         /**
 192          * @var float Like mTrxWriteQueryCount but excludes lock-bound, easy to replicate, queries
 193          */
 194         private $mTrxWriteAdjDuration = 0.0;
 195         /**
 196          * @var integer Number of write queries counted in mTrxWriteAdjDuration
 197          */
 198         private $mTrxWriteAdjQueryCount = 0;
 199         /**
 200          * @var float RTT time estimate
 201          */
 202         private $mRTTEstimate = 0.0;
 203
 204         /** @var array Map of (name => 1) for locks obtained via lock() */
 205         private $mNamedLocksHeld = [];
 206
 207         /** @var IDatabase|null Lazy handle to the master DB this server replicates from */
 208         private $lazyMasterHandle;
 209
 210         /**
 211          * @since 1.21
 212          * @var resource File handle for upgrade
 213          */
 214         protected $fileHandle = null;
 215
 216         /**
 217          * @since 1.22
 218          * @var string[] Process cache of VIEWs names in the database
 219          */
 220         protected $allViews = null;
 221
 222         /** @var float UNIX timestamp */
 223         protected $lastPing = 0.0;
 224
 225         /** @var int[] Prior mFlags values */
 226         private $priorFlags = [];
 227
 228         /** @var object|string Class name or object With profileIn/profileOut methods */
 229         protected $profiler;
 230         /** @var TransactionProfiler */
 231         protected $trxProfiler;
 232
 233         /**
 234          * Constructor and database handle and attempt to connect to the DB server
 235          *
 236          * IDatabase classes should not be constructed directly in external
 237          * code. Database::factory() should be used instead.
 238          *
 239          * @param array $params Parameters passed from Database::factory()
 240          */
 241         function __construct( array $params ) {
 242                 $server = $params['host'];
 243                 $user = $params['user'];
 244                 $password = $params['password'];
 245                 $dbName = $params['dbname'];
 246                 $flags = $params['flags'];
 247
 248                 $this->mSchema = $params['schema'];
 249                 $this->mTablePrefix = $params['tablePrefix'];
 250
 251                 $this->cliMode = isset( $params['cliMode'] )
 252                         ? $params['cliMode']
 253                         : ( PHP_SAPI === 'cli' );
 254                 $this->agent = isset( $params['agent'] )
 255                         ? str_replace( '/', '-', $params['agent'] ) // escape for comment
 256                         : '';
 257
 258                 $this->mFlags = $flags;
 259                 if ( $this->mFlags & DBO_DEFAULT ) {
 260                         if ( $this->cliMode ) {
 261                                 $this->mFlags &= ~DBO_TRX;
 262                         } else {
 263                                 $this->mFlags |= DBO_TRX;
 264                         }
 265                 }
 266
 267                 $this->mSessionVars = $params['variables'];
 268
 269                 $this->srvCache = isset( $params['srvCache'] )
 270                         ? $params['srvCache']
 271                         : new HashBagOStuff();
 272
 273                 $this->profiler = isset( $params['profiler'] ) ? $params['profiler'] : null;
 274                 $this->trxProfiler = isset( $params['trxProfiler'] )
 275                         ? $params['trxProfiler']
 276                         : new TransactionProfiler();
 277                 $this->connLogger = isset( $params['connLogger'] )
 278                         ? $params['connLogger']
 279                         : new \Psr\Log\NullLogger();
 280                 $this->queryLogger = isset( $params['queryLogger'] )
 281                         ? $params['queryLogger']
 282                         : new \Psr\Log\NullLogger();
 283
 284                 // Set initial dummy domain until open() sets the final DB/prefix
 285                 $this->currentDomain = DatabaseDomain::newUnspecified();
 286
 287                 if ( $user ) {
 288                         $this->open( $server, $user, $password, $dbName );
 289                 } elseif ( $this->requiresDatabaseUser() ) {
 290                         throw new InvalidArgumentException( "No database user provided." );
 291                 }
 292
 293                 // Set the domain object after open() sets the relevant fields
 294                 if ( $this->mDBname != '' ) {
 295                         // Domains with server scope but a table prefix are not used by IDatabase classes
 296                         $this->currentDomain = new DatabaseDomain( $this->mDBname, null, $this->mTablePrefix );
 297                 }
 298         }
 299
 300         /**
 301          * Construct a Database subclass instance given a database type and parameters
 302          *
 303          * This also connects to the database immediately upon object construction
 304          *
 305          * @param string $dbType A possible DB type (sqlite, mysql, postgres)
 306          * @param array $p Parameter map with keys:
 307          *   - host : The hostname of the DB server
 308          *   - user : The name of the database user the client operates under
 309          *   - password : The password for the database user
 310          *   - dbname : The name of the database to use where queries do not specify one.
 311          *      The database must exist or an error might be thrown. Setting this to the empty string
 312          *      will avoid any such errors and make the handle have no implicit database scope. This is
 313          *      useful for queries like SHOW STATUS, CREATE DATABASE, or DROP DATABASE. Note that a
 314          *      "database" in Postgres is rougly equivalent to an entire MySQL server. This the domain
 315          *      in which user names and such are defined, e.g. users are database-specific in Postgres.
 316          *   - schema : The database schema to use (if supported). A "schema" in Postgres is roughly
 317          *      equivalent to a "database" in MySQL. Note that MySQL and SQLite do not use schemas.
 318          *   - tablePrefix : Optional table prefix that is implicitly added on to all table names
 319          *      recognized in queries. This can be used in place of schemas for handle site farms.
 320          *   - flags : Optional bitfield of DBO_* constants that define connection, protocol,
 321          *      buffering, and transaction behavior. It is STRONGLY adviced to leave the DBO_DEFAULT
 322          *      flag in place UNLESS this this database simply acts as a key/value store.
 323          *   - driver: Optional name of a specific DB client driver. For MySQL, there is the old
 324          *      'mysql' driver and the newer 'mysqli' driver.
 325          *   - variables: Optional map of session variables to set after connecting. This can be
 326          *      used to adjust lock timeouts or encoding modes and the like.
 327          *   - connLogger: Optional PSR-3 logger interface instance.
 328          *   - queryLogger: Optional PSR-3 logger interface instance.
 329          *   - profiler: Optional class name or object with profileIn()/profileOut() methods.
 330          *      These will be called in query(), using a simplified version of the SQL that also
 331          *      includes the agent as a SQL comment.
 332          *   - trxProfiler: Optional TransactionProfiler instance.
 333          *   - errorLogger: Optional callback that takes an Exception and logs it.
 334          *   - cliMode: Whether to consider the execution context that of a CLI script.
 335          *   - agent: Optional name used to identify the end-user in query profiling/logging.
 336          *   - srvCache: Optional BagOStuff instance to an APC-style cache.
 337          * @return Database|null If the database driver or extension cannot be found
 338          * @throws InvalidArgumentException If the database driver or extension cannot be found
 339          * @since 1.18
 340          */
 341         final public static function factory( $dbType, $p = [] ) {
 342                 static $canonicalDBTypes = [
 343                         'mysql' => [ 'mysqli', 'mysql' ],
 344                         'postgres' => [],
 345                         'sqlite' => [],
 346                         'oracle' => [],
 347                         'mssql' => [],
 348                 ];
 349
 350                 $driver = false;
 351                 $dbType = strtolower( $dbType );
 352                 if ( isset( $canonicalDBTypes[$dbType] ) && $canonicalDBTypes[$dbType] ) {
 353                         $possibleDrivers = $canonicalDBTypes[$dbType];
 354                         if ( !empty( $p['driver'] ) ) {
 355                                 if ( in_array( $p['driver'], $possibleDrivers ) ) {
 356                                         $driver = $p['driver'];
 357                                 } else {
 358                                         throw new InvalidArgumentException( __METHOD__ .
 359                                                 " type '$dbType' does not support driver '{$p['driver']}'" );
 360                                 }
 361                         } else {
 362                                 foreach ( $possibleDrivers as $posDriver ) {
 363                                         if ( extension_loaded( $posDriver ) ) {
 364                                                 $driver = $posDriver;
 365                                                 break;
 366                                         }
 367                                 }
 368                         }
 369                 } else {
 370                         $driver = $dbType;
 371                 }
 372                 if ( $driver === false ) {
 373                         throw new InvalidArgumentException( __METHOD__ .
 374                                 " no viable database extension found for type '$dbType'" );
 375                 }
 376
 377                 $class = 'Database' . ucfirst( $driver );
 378                 if ( class_exists( $class ) && is_subclass_of( $class, 'IDatabase' ) ) {
 379                         // Resolve some defaults for b/c
 380                         $p['host'] = isset( $p['host'] ) ? $p['host'] : false;
 381                         $p['user'] = isset( $p['user'] ) ? $p['user'] : false;
 382                         $p['password'] = isset( $p['password'] ) ? $p['password'] : false;
 383                         $p['dbname'] = isset( $p['dbname'] ) ? $p['dbname'] : false;
 384                         $p['flags'] = isset( $p['flags'] ) ? $p['flags'] : 0;
 385                         $p['variables'] = isset( $p['variables'] ) ? $p['variables'] : [];
 386                         $p['tablePrefix'] = isset( $p['tablePrefix'] ) ? $p['tablePrefix'] : '';
 387                         $p['schema'] = isset( $p['schema'] ) ? $p['schema'] : '';
 388                         $p['foreign'] = isset( $p['foreign'] ) ? $p['foreign'] : false;
 389
 390                         $conn = new $class( $p );
 391                         if ( isset( $p['connLogger'] ) ) {
 392                                 $conn->connLogger = $p['connLogger'];
 393                         }
 394                         if ( isset( $p['queryLogger'] ) ) {
 395                                 $conn->queryLogger = $p['queryLogger'];
 396                         }
 397                         if ( isset( $p['errorLogger'] ) ) {
 398                                 $conn->errorLogger = $p['errorLogger'];
 399                         } else {
 400                                 $conn->errorLogger = function ( Exception $e ) {
 401                                         trigger_error( get_class( $e ) . ': ' . $e->getMessage(), E_WARNING );
 402                                 };
 403                         }
 404                 } else {
 405                         $conn = null;
 406                 }
 407
 408                 return $conn;
 409         }
 410
 411         public function setLogger( LoggerInterface $logger ) {
 412                 $this->queryLogger = $logger;
 413         }
 414
 415         public function getServerInfo() {
 416                 return $this->getServerVersion();
 417         }
 418
 419         public function bufferResults( $buffer = null ) {
 420                 $res = !$this->getFlag( DBO_NOBUFFER );
 421                 if ( $buffer !== null ) {
 422                         $buffer ? $this->clearFlag( DBO_NOBUFFER ) : $this->setFlag( DBO_NOBUFFER );
 423                 }
 424
 425                 return $res;
 426         }
 427
 428         /**
 429          * Turns on (false) or off (true) the automatic generation and sending
 430          * of a "we're sorry, but there has been a database error" page on
 431          * database errors. Default is on (false). When turned off, the
 432          * code should use lastErrno() and lastError() to handle the
 433          * situation as appropriate.
 434          *
 435          * Do not use this function outside of the Database classes.
 436          *
 437          * @param null|bool $ignoreErrors
 438          * @return bool The previous value of the flag.
 439          */
 440         protected function ignoreErrors( $ignoreErrors = null ) {
 441                 $res = $this->getFlag( DBO_IGNORE );
 442                 if ( $ignoreErrors !== null ) {
 443                         $ignoreErrors ? $this->setFlag( DBO_IGNORE ) : $this->clearFlag( DBO_IGNORE );
 444                 }
 445
 446                 return $res;
 447         }
 448
 449         public function trxLevel() {
 450                 return $this->mTrxLevel;
 451         }
 452
 453         public function trxTimestamp() {
 454                 return $this->mTrxLevel ? $this->mTrxTimestamp : null;
 455         }
 456
 457         public function tablePrefix( $prefix = null ) {
 458                 $old = $this->mTablePrefix;
 459                 if ( $prefix !== null ) {
 460                         $this->mTablePrefix = $prefix;
 461                         $this->currentDomain = ( $this->mDBname != '' )
 462                                 ? new DatabaseDomain( $this->mDBname, null, $this->mTablePrefix )
 463                                 : DatabaseDomain::newUnspecified();
 464                 }
 465
 466                 return $old;
 467         }
 468
 469         public function dbSchema( $schema = null ) {
 470                 $old = $this->mSchema;
 471                 if ( $schema !== null ) {
 472                         $this->mSchema = $schema;
 473                 }
 474
 475                 return $old;
 476         }
 477
 478         /**
 479          * Set the filehandle to copy write statements to.
 480          *
 481          * @param resource $fh File handle
 482          */
 483         public function setFileHandle( $fh ) {
 484                 $this->fileHandle = $fh;
 485         }
 486
 487         public function getLBInfo( $name = null ) {
 488                 if ( is_null( $name ) ) {
 489                         return $this->mLBInfo;
 490                 } else {
 491                         if ( array_key_exists( $name, $this->mLBInfo ) ) {
 492                                 return $this->mLBInfo[$name];
 493                         } else {
 494                                 return null;
 495                         }
 496                 }
 497         }
 498
 499         public function setLBInfo( $name, $value = null ) {
 500                 if ( is_null( $value ) ) {
 501                         $this->mLBInfo = $name;
 502                 } else {
 503                         $this->mLBInfo[$name] = $value;
 504                 }
 505         }
 506
 507         public function setLazyMasterHandle( IDatabase $conn ) {
 508                 $this->lazyMasterHandle = $conn;
 509         }
 510
 511         /**
 512          * @return IDatabase|null
 513          * @see setLazyMasterHandle()
 514          * @since 1.27
 515          */
 516         public function getLazyMasterHandle() {
 517                 return $this->lazyMasterHandle;
 518         }
 519
 520         public function implicitGroupby() {
 521                 return true;
 522         }
 523
 524         public function implicitOrderby() {
 525                 return true;
 526         }
 527
 528         public function lastQuery() {
 529                 return $this->mLastQuery;
 530         }
 531
 532         public function doneWrites() {
 533                 return (bool)$this->mDoneWrites;
 534         }
 535
 536         public function lastDoneWrites() {
 537                 return $this->mDoneWrites ?: false;
 538         }
 539
 540         public function writesPending() {
 541                 return $this->mTrxLevel && $this->mTrxDoneWrites;
 542         }
 543
 544         public function writesOrCallbacksPending() {
 545                 return $this->mTrxLevel && (
 546                         $this->mTrxDoneWrites || $this->mTrxIdleCallbacks || $this->mTrxPreCommitCallbacks
 547                 );
 548         }
 549
 550         public function pendingWriteQueryDuration( $type = self::ESTIMATE_TOTAL ) {
 551                 if ( !$this->mTrxLevel ) {
 552                         return false;
 553                 } elseif ( !$this->mTrxDoneWrites ) {
 554                         return 0.0;
 555                 }
 556
 557                 switch ( $type ) {
 558                         case self::ESTIMATE_DB_APPLY:
 559                                 $this->ping( $rtt );
 560                                 $rttAdjTotal = $this->mTrxWriteAdjQueryCount * $rtt;
 561                                 $applyTime = max( $this->mTrxWriteAdjDuration - $rttAdjTotal, 0 );
 562                                 // For omitted queries, make them count as something at least
 563                                 $omitted = $this->mTrxWriteQueryCount - $this->mTrxWriteAdjQueryCount;
 564                                 $applyTime += self::TINY_WRITE_SEC * $omitted;
 565
 566                                 return $applyTime;
 567                         default: // everything
 568                                 return $this->mTrxWriteDuration;
 569                 }
 570         }
 571
 572         public function pendingWriteCallers() {
 573                 return $this->mTrxLevel ? $this->mTrxWriteCallers : [];
 574         }
 575
 576         protected function pendingWriteAndCallbackCallers() {
 577                 if ( !$this->mTrxLevel ) {
 578                         return [];
 579                 }
 580
 581                 $fnames = $this->mTrxWriteCallers;
 582                 foreach ( [
 583                         $this->mTrxIdleCallbacks,
 584                         $this->mTrxPreCommitCallbacks,
 585                         $this->mTrxEndCallbacks
 586                 ] as $callbacks ) {
 587                         foreach ( $callbacks as $callback ) {
 588                                 $fnames[] = $callback[1];
 589                         }
 590                 }
 591
 592                 return $fnames;
 593         }
 594
 595         public function isOpen() {
 596                 return $this->mOpened;
 597         }
 598
 599         public function setFlag( $flag, $remember = self::REMEMBER_NOTHING ) {
 600                 if ( $remember === self::REMEMBER_PRIOR ) {
 601                         array_push( $this->priorFlags, $this->mFlags );
 602                 }
 603                 $this->mFlags |= $flag;
 604         }
 605
 606         public function clearFlag( $flag, $remember = self::REMEMBER_NOTHING ) {
 607                 if ( $remember === self::REMEMBER_PRIOR ) {
 608                         array_push( $this->priorFlags, $this->mFlags );
 609                 }
 610                 $this->mFlags &= ~$flag;
 611         }
 612
 613         public function restoreFlags( $state = self::RESTORE_PRIOR ) {
 614                 if ( !$this->priorFlags ) {
 615                         return;
 616                 }
 617
 618                 if ( $state === self::RESTORE_INITIAL ) {
 619                         $this->mFlags = reset( $this->priorFlags );
 620                         $this->priorFlags = [];
 621                 } else {
 622                         $this->mFlags = array_pop( $this->priorFlags );
 623                 }
 624         }
 625
 626         public function getFlag( $flag ) {
 627                 return !!( $this->mFlags & $flag );
 628         }
 629
 630         public function getProperty( $name ) {
 631                 return $this->$name;
 632         }
 633
 634         public function getDomainID() {
 635                 return $this->currentDomain->getId();
 636         }
 637
 638         final public function getWikiID() {
 639                 return $this->getDomainID();
 640         }
 641
 642         /**
 643          * Get information about an index into an object
 644          * @param string $table Table name
 645          * @param string $index Index name
 646          * @param string $fname Calling function name
 647          * @return mixed Database-specific index description class or false if the index does not exist
 648          */
 649         abstract function indexInfo( $table, $index, $fname = __METHOD__ );
 650
 651         /**
 652          * Wrapper for addslashes()
 653          *
 654          * @param string $s String to be slashed.
 655          * @return string Slashed string.
 656          */
 657         abstract function strencode( $s );
 658
 659         protected function installErrorHandler() {
 660                 $this->mPHPError = false;
 661                 $this->htmlErrors = ini_set( 'html_errors', '0' );
 662                 set_error_handler( [ $this, 'connectionerrorLogger' ] );
 663         }
 664
 665         /**
 666          * @return bool|string
 667          */
 668         protected function restoreErrorHandler() {
 669                 restore_error_handler();
 670                 if ( $this->htmlErrors !== false ) {
 671                         ini_set( 'html_errors', $this->htmlErrors );
 672                 }
 673                 if ( $this->mPHPError ) {
 674                         $error = preg_replace( '!\[<a.*</a>\]!', '', $this->mPHPError );
 675                         $error = preg_replace( '!^.*?:\s?(.*)$!', '$1', $error );
 676
 677                         return $error;
 678                 } else {
 679                         return false;
 680                 }
 681         }
 682
 683         /**
 684          * @param int $errno
 685          * @param string $errstr
 686          */
 687         public function connectionerrorLogger( $errno, $errstr ) {
 688                 $this->mPHPError = $errstr;
 689         }
 690
 691         /**
 692          * Create a log context to pass to PSR-3 logger functions.
 693          *
 694          * @param array $extras Additional data to add to context
 695          * @return array
 696          */
 697         protected function getLogContext( array $extras = [] ) {
 698                 return array_merge(
 699                         [
 700                                 'db_server' => $this->mServer,
 701                                 'db_name' => $this->mDBname,
 702                                 'db_user' => $this->mUser,
 703                         ],
 704                         $extras
 705                 );
 706         }
 707
 708         public function close() {
 709                 if ( $this->mConn ) {
 710                         if ( $this->trxLevel() ) {
 711                                 $this->commit( __METHOD__, self::FLUSHING_INTERNAL );
 712                         }
 713
 714                         $closed = $this->closeConnection();
 715                         $this->mConn = false;
 716                 } elseif ( $this->mTrxIdleCallbacks || $this->mTrxEndCallbacks ) { // sanity
 717                         throw new RuntimeException( "Transaction callbacks still pending." );
 718                 } else {
 719                         $closed = true;
 720                 }
 721                 $this->mOpened = false;
 722
 723                 return $closed;
 724         }
 725
 726         /**
 727          * Make sure isOpen() returns true as a sanity check
 728          *
 729          * @throws DBUnexpectedError
 730          */
 731         protected function assertOpen() {
 732                 if ( !$this->isOpen() ) {
 733                         throw new DBUnexpectedError( $this, "DB connection was already closed." );
 734                 }
 735         }
 736
 737         /**
 738          * Closes underlying database connection
 739          * @since 1.20
 740          * @return bool Whether connection was closed successfully
 741          */
 742         abstract protected function closeConnection();
 743
 744         function reportConnectionError( $error = 'Unknown error' ) {
 745                 $myError = $this->lastError();
 746                 if ( $myError ) {
 747                         $error = $myError;
 748                 }
 749
 750                 # New method
 751                 throw new DBConnectionError( $this, $error );
 752         }
 753
 754         /**
 755          * The DBMS-dependent part of query()
 756          *
 757          * @param string $sql SQL query.
 758          * @return ResultWrapper|bool Result object to feed to fetchObject,
 759          *   fetchRow, ...; or false on failure
 760          */
 761         abstract protected function doQuery( $sql );
 762
 763         /**
 764          * Determine whether a query writes to the DB.
 765          * Should return true if unsure.
 766          *
 767          * @param string $sql
 768          * @return bool
 769          */
 770         protected function isWriteQuery( $sql ) {
 771                 return !preg_match(
 772                         '/^(?:SELECT|BEGIN|ROLLBACK|COMMIT|SET|SHOW|EXPLAIN|\(SELECT)\b/i', $sql );
 773         }
 774
 775         /**
 776          * @param $sql
 777          * @return string|null
 778          */
 779         protected function getQueryVerb( $sql ) {
 780                 return preg_match( '/^\s*([a-z]+)/i', $sql, $m ) ? strtoupper( $m[1] ) : null;
 781         }
 782
 783         /**
 784          * Determine whether a SQL statement is sensitive to isolation level.
 785          * A SQL statement is considered transactable if its result could vary
 786          * depending on the transaction isolation level. Operational commands
 787          * such as 'SET' and 'SHOW' are not considered to be transactable.
 788          *
 789          * @param string $sql
 790          * @return bool
 791          */
 792         protected function isTransactableQuery( $sql ) {
 793                 $verb = $this->getQueryVerb( $sql );
 794                 return !in_array( $verb, [ 'BEGIN', 'COMMIT', 'ROLLBACK', 'SHOW', 'SET' ], true );
 795         }
 796
 797         public function query( $sql, $fname = __METHOD__, $tempIgnore = false ) {
 798                 $priorWritesPending = $this->writesOrCallbacksPending();
 799                 $this->mLastQuery = $sql;
 800
 801                 $isWrite = $this->isWriteQuery( $sql );
 802                 if ( $isWrite ) {
 803                         $reason = $this->getReadOnlyReason();
 804                         if ( $reason !== false ) {
 805                                 throw new DBReadOnlyError( $this, "Database is read-only: $reason" );
 806                         }
 807                         # Set a flag indicating that writes have been done
 808                         $this->mDoneWrites = microtime( true );
 809                 }
 810
 811                 // Add trace comment to the begin of the sql string, right after the operator.
 812                 // Or, for one-word queries (like "BEGIN" or COMMIT") add it to the end (bug 42598)
 813                 $commentedSql = preg_replace( '/\s|$/', " /* $fname {$this->agent} */ ", $sql, 1 );
 814
 815                 # Start implicit transactions that wrap the request if DBO_TRX is enabled
 816                 if ( !$this->mTrxLevel && $this->getFlag( DBO_TRX )
 817                         && $this->isTransactableQuery( $sql )
 818                 ) {
 819                         $this->begin( __METHOD__ . " ($fname)", self::TRANSACTION_INTERNAL );
 820                         $this->mTrxAutomatic = true;
 821                 }
 822
 823                 # Keep track of whether the transaction has write queries pending
 824                 if ( $this->mTrxLevel && !$this->mTrxDoneWrites && $isWrite ) {
 825                         $this->mTrxDoneWrites = true;
 826                         $this->trxProfiler->transactionWritingIn(
 827                                 $this->mServer, $this->mDBname, $this->mTrxShortId );
 828                 }
 829
 830                 if ( $this->getFlag( DBO_DEBUG ) ) {
 831                         $this->queryLogger->debug( "{$this->mDBname} {$commentedSql}" );
 832                 }
 833
 834                 # Avoid fatals if close() was called
 835                 $this->assertOpen();
 836
 837                 # Send the query to the server
 838                 $ret = $this->doProfiledQuery( $sql, $commentedSql, $isWrite, $fname );
 839
 840                 # Try reconnecting if the connection was lost
 841                 if ( false === $ret && $this->wasErrorReissuable() ) {
 842                         $recoverable = $this->canRecoverFromDisconnect( $sql, $priorWritesPending );
 843                         # Stash the last error values before anything might clear them
 844                         $lastError = $this->lastError();
 845                         $lastErrno = $this->lastErrno();
 846                         # Update state tracking to reflect transaction loss due to disconnection
 847                         $this->handleTransactionLoss();
 848                         if ( $this->reconnect() ) {
 849                                 $msg = __METHOD__ . ": lost connection to {$this->getServer()}; reconnected";
 850                                 $this->connLogger->warning( $msg );
 851                                 $this->queryLogger->warning(
 852                                         "$msg:\n" . ( new RuntimeException() )->getTraceAsString() );
 853
 854                                 if ( !$recoverable ) {
 855                                         # Callers may catch the exception and continue to use the DB
 856                                         $this->reportQueryError( $lastError, $lastErrno, $sql, $fname );
 857                                 } else {
 858                                         # Should be safe to silently retry the query
 859                                         $ret = $this->doProfiledQuery( $sql, $commentedSql, $isWrite, $fname );
 860                                 }
 861                         } else {
 862                                 $msg = __METHOD__ . ": lost connection to {$this->getServer()} permanently";
 863                                 $this->connLogger->error( $msg );
 864                         }
 865                 }
 866
 867                 if ( false === $ret ) {
 868                         # Deadlocks cause the entire transaction to abort, not just the statement.
 869                         # http://dev.mysql.com/doc/refman/5.7/en/innodb-error-handling.html
 870                         # https://www.postgresql.org/docs/9.1/static/explicit-locking.html
 871                         if ( $this->wasDeadlock() ) {
 872                                 if ( $this->explicitTrxActive() || $priorWritesPending ) {
 873                                         $tempIgnore = false; // not recoverable
 874                                 }
 875                                 # Update state tracking to reflect transaction loss
 876                                 $this->handleTransactionLoss();
 877                         }
 878
 879                         $this->reportQueryError(
 880                                 $this->lastError(), $this->lastErrno(), $sql, $fname, $tempIgnore );
 881                 }
 882
 883                 $res = $this->resultObject( $ret );
 884
 885                 return $res;
 886         }
 887
 888         private function doProfiledQuery( $sql, $commentedSql, $isWrite, $fname ) {
 889                 $isMaster = !is_null( $this->getLBInfo( 'master' ) );
 890                 # generalizeSQL() will probably cut down the query to reasonable
 891                 # logging size most of the time. The substr is really just a sanity check.
 892                 if ( $isMaster ) {
 893                         $queryProf = 'query-m: ' . substr( self::generalizeSQL( $sql ), 0, 255 );
 894                 } else {
 895                         $queryProf = 'query: ' . substr( self::generalizeSQL( $sql ), 0, 255 );
 896                 }
 897
 898                 # Include query transaction state
 899                 $queryProf .= $this->mTrxShortId ? " [TRX#{$this->mTrxShortId}]" : "";
 900
 901                 $startTime = microtime( true );
 902                 if ( $this->profiler ) {
 903                         call_user_func( [ $this->profiler, 'profileIn' ], $queryProf );
 904                 }
 905                 $ret = $this->doQuery( $commentedSql );
 906                 if ( $this->profiler ) {
 907                         call_user_func( [ $this->profiler, 'profileOut' ], $queryProf );
 908                 }
 909                 $queryRuntime = max( microtime( true ) - $startTime, 0.0 );
 910
 911                 unset( $queryProfSection ); // profile out (if set)
 912
 913                 if ( $ret !== false ) {
 914                         $this->lastPing = $startTime;
 915                         if ( $isWrite && $this->mTrxLevel ) {
 916                                 $this->updateTrxWriteQueryTime( $sql, $queryRuntime );
 917                                 $this->mTrxWriteCallers[] = $fname;
 918                         }
 919                 }
 920
 921                 if ( $sql === self::PING_QUERY ) {
 922                         $this->mRTTEstimate = $queryRuntime;
 923                 }
 924
 925                 $this->trxProfiler->recordQueryCompletion(
 926                         $queryProf, $startTime, $isWrite, $this->affectedRows()
 927                 );
 928                 $this->queryLogger->debug( $sql, [
 929                         'method' => $fname,
 930                         'master' => $isMaster,
 931                         'runtime' => $queryRuntime,
 932                 ] );
 933
 934                 return $ret;
 935         }
 936
 937         /**
 938          * Update the estimated run-time of a query, not counting large row lock times
 939          *
 940          * LoadBalancer can be set to rollback transactions that will create huge replication
 941          * lag. It bases this estimate off of pendingWriteQueryDuration(). Certain simple
 942          * queries, like inserting a row can take a long time due to row locking. This method
 943          * uses some simple heuristics to discount those cases.
 944          *
 945          * @param string $sql A SQL write query
 946          * @param float $runtime Total runtime, including RTT
 947          */
 948         private function updateTrxWriteQueryTime( $sql, $runtime ) {
 949                 // Whether this is indicative of replica DB runtime (except for RBR or ws_repl)
 950                 $indicativeOfReplicaRuntime = true;
 951                 if ( $runtime > self::SLOW_WRITE_SEC ) {
 952                         $verb = $this->getQueryVerb( $sql );
 953                         // insert(), upsert(), replace() are fast unless bulky in size or blocked on locks
 954                         if ( $verb === 'INSERT' ) {
 955                                 $indicativeOfReplicaRuntime = $this->affectedRows() > self::SMALL_WRITE_ROWS;
 956                         } elseif ( $verb === 'REPLACE' ) {
 957                                 $indicativeOfReplicaRuntime = $this->affectedRows() > self::SMALL_WRITE_ROWS / 2;
 958                         }
 959                 }
 960
 961                 $this->mTrxWriteDuration += $runtime;
 962                 $this->mTrxWriteQueryCount += 1;
 963                 if ( $indicativeOfReplicaRuntime ) {
 964                         $this->mTrxWriteAdjDuration += $runtime;
 965                         $this->mTrxWriteAdjQueryCount += 1;
 966                 }
 967         }
 968
 969         private function canRecoverFromDisconnect( $sql, $priorWritesPending ) {
 970                 # Transaction dropped; this can mean lost writes, or REPEATABLE-READ snapshots.
 971                 # Dropped connections also mean that named locks are automatically released.
 972                 # Only allow error suppression in autocommit mode or when the lost transaction
 973                 # didn't matter anyway (aside from DBO_TRX snapshot loss).
 974                 if ( $this->mNamedLocksHeld ) {
 975                         return false; // possible critical section violation
 976                 } elseif ( $sql === 'COMMIT' ) {
 977                         return !$priorWritesPending; // nothing written anyway? (T127428)
 978                 } elseif ( $sql === 'ROLLBACK' ) {
 979                         return true; // transaction lost...which is also what was requested :)
 980                 } elseif ( $this->explicitTrxActive() ) {
 981                         return false; // don't drop atomocity
 982                 } elseif ( $priorWritesPending ) {
 983                         return false; // prior writes lost from implicit transaction
 984                 }
 985
 986                 return true;
 987         }
 988
 989         private function handleTransactionLoss() {
 990                 $this->mTrxLevel = 0;
 991                 $this->mTrxIdleCallbacks = []; // bug 65263
 992                 $this->mTrxPreCommitCallbacks = []; // bug 65263
 993                 try {
 994                         // Handle callbacks in mTrxEndCallbacks
 995                         $this->runOnTransactionIdleCallbacks( self::TRIGGER_ROLLBACK );
 996                         $this->runTransactionListenerCallbacks( self::TRIGGER_ROLLBACK );
 997                         return null;
 998                 } catch ( Exception $e ) {
 999                         // Already logged; move on...
1000                         return $e;
1001                 }
1002         }
1003
1004         public function reportQueryError( $error, $errno, $sql, $fname, $tempIgnore = false ) {
1005                 if ( $this->ignoreErrors() || $tempIgnore ) {
1006                         $this->queryLogger->debug( "SQL ERROR (ignored): $error\n" );
1007                 } else {
1008                         $sql1line = mb_substr( str_replace( "\n", "\\n", $sql ), 0, 5 * 1024 );
1009                         $this->queryLogger->error(
1010                                 "{fname}\t{db_server}\t{errno}\t{error}\t{sql1line}",
1011                                 $this->getLogContext( [
1012                                         'method' => __METHOD__,
1013                                         'errno' => $errno,
1014                                         'error' => $error,
1015                                         'sql1line' => $sql1line,
1016                                         'fname' => $fname,
1017                                 ] )
1018                         );
1019                         $this->queryLogger->debug( "SQL ERROR: " . $error . "\n" );
1020                         throw new DBQueryError( $this, $error, $errno, $sql, $fname );
1021                 }
1022         }
1023
1024         public function freeResult( $res ) {
1025         }
1026
1027         public function selectField(
1028                 $table, $var, $cond = '', $fname = __METHOD__, $options = []
1029         ) {
1030                 if ( $var === '*' ) { // sanity
1031                         throw new DBUnexpectedError( $this, "Cannot use a * field: got '$var'" );
1032                 }
1033
1034                 if ( !is_array( $options ) ) {
1035                         $options = [ $options ];
1036                 }
1037
1038                 $options['LIMIT'] = 1;
1039
1040                 $res = $this->select( $table, $var, $cond, $fname, $options );
1041                 if ( $res === false || !$this->numRows( $res ) ) {
1042                         return false;
1043                 }
1044
1045                 $row = $this->fetchRow( $res );
1046
1047                 if ( $row !== false ) {
1048                         return reset( $row );
1049                 } else {
1050                         return false;
1051                 }
1052         }
1053
1054         public function selectFieldValues(
1055                 $table, $var, $cond = '', $fname = __METHOD__, $options = [], $join_conds = []
1056         ) {
1057                 if ( $var === '*' ) { // sanity
1058                         throw new DBUnexpectedError( $this, "Cannot use a * field" );
1059                 } elseif ( !is_string( $var ) ) { // sanity
1060                         throw new DBUnexpectedError( $this, "Cannot use an array of fields" );
1061                 }
1062
1063                 if ( !is_array( $options ) ) {
1064                         $options = [ $options ];
1065                 }
1066
1067                 $res = $this->select( $table, $var, $cond, $fname, $options, $join_conds );
1068                 if ( $res === false ) {
1069                         return false;
1070                 }
1071
1072                 $values = [];
1073                 foreach ( $res as $row ) {
1074                         $values[] = $row->$var;
1075                 }
1076
1077                 return $values;
1078         }
1079
1080         /**
1081          * Returns an optional USE INDEX clause to go after the table, and a
1082          * string to go at the end of the query.
1083          *
1084          * @param array $options Associative array of options to be turned into
1085          *   an SQL query, valid keys are listed in the function.
1086          * @return array
1087          * @see DatabaseBase::select()
1088          */
1089         public function makeSelectOptions( $options ) {
1090                 $preLimitTail = $postLimitTail = '';
1091                 $startOpts = '';
1092
1093                 $noKeyOptions = [];
1094
1095                 foreach ( $options as $key => $option ) {
1096                         if ( is_numeric( $key ) ) {
1097                                 $noKeyOptions[$option] = true;
1098                         }
1099                 }
1100
1101                 $preLimitTail .= $this->makeGroupByWithHaving( $options );
1102
1103                 $preLimitTail .= $this->makeOrderBy( $options );
1104
1105                 // if (isset($options['LIMIT'])) {
1106                 //      $tailOpts .= $this->limitResult('', $options['LIMIT'],
1107                 //              isset($options['OFFSET']) ? $options['OFFSET']
1108                 //              : false);
1109                 // }
1110
1111                 if ( isset( $noKeyOptions['FOR UPDATE'] ) ) {
1112                         $postLimitTail .= ' FOR UPDATE';
1113                 }
1114
1115                 if ( isset( $noKeyOptions['LOCK IN SHARE MODE'] ) ) {
1116                         $postLimitTail .= ' LOCK IN SHARE MODE';
1117                 }
1118
1119                 if ( isset( $noKeyOptions['DISTINCT'] ) || isset( $noKeyOptions['DISTINCTROW'] ) ) {
1120                         $startOpts .= 'DISTINCT';
1121                 }
1122
1123                 # Various MySQL extensions
1124                 if ( isset( $noKeyOptions['STRAIGHT_JOIN'] ) ) {
1125                         $startOpts .= ' /*! STRAIGHT_JOIN */';
1126                 }
1127
1128                 if ( isset( $noKeyOptions['HIGH_PRIORITY'] ) ) {
1129                         $startOpts .= ' HIGH_PRIORITY';
1130                 }
1131
1132                 if ( isset( $noKeyOptions['SQL_BIG_RESULT'] ) ) {
1133                         $startOpts .= ' SQL_BIG_RESULT';
1134                 }
1135
1136                 if ( isset( $noKeyOptions['SQL_BUFFER_RESULT'] ) ) {
1137                         $startOpts .= ' SQL_BUFFER_RESULT';
1138                 }
1139
1140                 if ( isset( $noKeyOptions['SQL_SMALL_RESULT'] ) ) {
1141                         $startOpts .= ' SQL_SMALL_RESULT';
1142                 }
1143
1144                 if ( isset( $noKeyOptions['SQL_CALC_FOUND_ROWS'] ) ) {
1145                         $startOpts .= ' SQL_CALC_FOUND_ROWS';
1146                 }
1147
1148                 if ( isset( $noKeyOptions['SQL_CACHE'] ) ) {
1149                         $startOpts .= ' SQL_CACHE';
1150                 }
1151
1152                 if ( isset( $noKeyOptions['SQL_NO_CACHE'] ) ) {
1153                         $startOpts .= ' SQL_NO_CACHE';
1154                 }
1155
1156                 if ( isset( $options['USE INDEX'] ) && is_string( $options['USE INDEX'] ) ) {
1157                         $useIndex = $this->useIndexClause( $options['USE INDEX'] );
1158                 } else {
1159                         $useIndex = '';
1160                 }
1161                 if ( isset( $options['IGNORE INDEX'] ) && is_string( $options['IGNORE INDEX'] ) ) {
1162                         $ignoreIndex = $this->ignoreIndexClause( $options['IGNORE INDEX'] );
1163                 } else {
1164                         $ignoreIndex = '';
1165                 }
1166
1167                 return [ $startOpts, $useIndex, $preLimitTail, $postLimitTail, $ignoreIndex ];
1168         }
1169
1170         /**
1171          * Returns an optional GROUP BY with an optional HAVING
1172          *
1173          * @param array $options Associative array of options
1174          * @return string
1175          * @see DatabaseBase::select()
1176          * @since 1.21
1177          */
1178         public function makeGroupByWithHaving( $options ) {
1179                 $sql = '';
1180                 if ( isset( $options['GROUP BY'] ) ) {
1181                         $gb = is_array( $options['GROUP BY'] )
1182                                 ? implode( ',', $options['GROUP BY'] )
1183                                 : $options['GROUP BY'];
1184                         $sql .= ' GROUP BY ' . $gb;
1185                 }
1186                 if ( isset( $options['HAVING'] ) ) {
1187                         $having = is_array( $options['HAVING'] )
1188                                 ? $this->makeList( $options['HAVING'], self::LIST_AND )
1189                                 : $options['HAVING'];
1190                         $sql .= ' HAVING ' . $having;
1191                 }
1192
1193                 return $sql;
1194         }
1195
1196         /**
1197          * Returns an optional ORDER BY
1198          *
1199          * @param array $options Associative array of options
1200          * @return string
1201          * @see DatabaseBase::select()
1202          * @since 1.21
1203          */
1204         public function makeOrderBy( $options ) {
1205                 if ( isset( $options['ORDER BY'] ) ) {
1206                         $ob = is_array( $options['ORDER BY'] )
1207                                 ? implode( ',', $options['ORDER BY'] )
1208                                 : $options['ORDER BY'];
1209
1210                         return ' ORDER BY ' . $ob;
1211                 }
1212
1213                 return '';
1214         }
1215
1216         // See IDatabase::select for the docs for this function
1217         public function select( $table, $vars, $conds = '', $fname = __METHOD__,
1218                 $options = [], $join_conds = [] ) {
1219                 $sql = $this->selectSQLText( $table, $vars, $conds, $fname, $options, $join_conds );
1220
1221                 return $this->query( $sql, $fname );
1222         }
1223
1224         public function selectSQLText( $table, $vars, $conds = '', $fname = __METHOD__,
1225                 $options = [], $join_conds = []
1226         ) {
1227                 if ( is_array( $vars ) ) {
1228                         $vars = implode( ',', $this->fieldNamesWithAlias( $vars ) );
1229                 }
1230
1231                 $options = (array)$options;
1232                 $useIndexes = ( isset( $options['USE INDEX'] ) && is_array( $options['USE INDEX'] ) )
1233                         ? $options['USE INDEX']
1234                         : [];
1235                 $ignoreIndexes = ( isset( $options['IGNORE INDEX'] ) && is_array( $options['IGNORE INDEX'] ) )
1236                         ? $options['IGNORE INDEX']
1237                         : [];
1238
1239                 if ( is_array( $table ) ) {
1240                         $from = ' FROM ' .
1241                                 $this->tableNamesWithIndexClauseOrJOIN( $table, $useIndexes, $ignoreIndexes, $join_conds );
1242                 } elseif ( $table != '' ) {
1243                         if ( $table[0] == ' ' ) {
1244                                 $from = ' FROM ' . $table;
1245                         } else {
1246                                 $from = ' FROM ' .
1247                                         $this->tableNamesWithIndexClauseOrJOIN( [ $table ], $useIndexes, $ignoreIndexes, [] );
1248                         }
1249                 } else {
1250                         $from = '';
1251                 }
1252
1253                 list( $startOpts, $useIndex, $preLimitTail, $postLimitTail, $ignoreIndex ) =
1254                         $this->makeSelectOptions( $options );
1255
1256                 if ( !empty( $conds ) ) {
1257                         if ( is_array( $conds ) ) {
1258                                 $conds = $this->makeList( $conds, self::LIST_AND );
1259                         }
1260                         $sql = "SELECT $startOpts $vars $from $useIndex $ignoreIndex WHERE $conds $preLimitTail";
1261                 } else {
1262                         $sql = "SELECT $startOpts $vars $from $useIndex $ignoreIndex $preLimitTail";
1263                 }
1264
1265                 if ( isset( $options['LIMIT'] ) ) {
1266                         $sql = $this->limitResult( $sql, $options['LIMIT'],
1267                                 isset( $options['OFFSET'] ) ? $options['OFFSET'] : false );
1268                 }
1269                 $sql = "$sql $postLimitTail";
1270
1271                 if ( isset( $options['EXPLAIN'] ) ) {
1272                         $sql = 'EXPLAIN ' . $sql;
1273                 }
1274
1275                 return $sql;
1276         }
1277
1278         public function selectRow( $table, $vars, $conds, $fname = __METHOD__,
1279                 $options = [], $join_conds = []
1280         ) {
1281                 $options = (array)$options;
1282                 $options['LIMIT'] = 1;
1283                 $res = $this->select( $table, $vars, $conds, $fname, $options, $join_conds );
1284
1285                 if ( $res === false ) {
1286                         return false;
1287                 }
1288
1289                 if ( !$this->numRows( $res ) ) {
1290                         return false;
1291                 }
1292
1293                 $obj = $this->fetchObject( $res );
1294
1295                 return $obj;
1296         }
1297
1298         public function estimateRowCount(
1299                 $table, $vars = '*', $conds = '', $fname = __METHOD__, $options = []
1300         ) {
1301                 $rows = 0;
1302                 $res = $this->select( $table, [ 'rowcount' => 'COUNT(*)' ], $conds, $fname, $options );
1303
1304                 if ( $res ) {
1305                         $row = $this->fetchRow( $res );
1306                         $rows = ( isset( $row['rowcount'] ) ) ? (int)$row['rowcount'] : 0;
1307                 }
1308
1309                 return $rows;
1310         }
1311
1312         public function selectRowCount(
1313                 $tables, $vars = '*', $conds = '', $fname = __METHOD__, $options = [], $join_conds = []
1314         ) {
1315                 $rows = 0;
1316                 $sql = $this->selectSQLText( $tables, '1', $conds, $fname, $options, $join_conds );
1317                 $res = $this->query( "SELECT COUNT(*) AS rowcount FROM ($sql) tmp_count", $fname );
1318
1319                 if ( $res ) {
1320                         $row = $this->fetchRow( $res );
1321                         $rows = ( isset( $row['rowcount'] ) ) ? (int)$row['rowcount'] : 0;
1322                 }
1323
1324                 return $rows;
1325         }
1326
1327         /**
1328          * Removes most variables from an SQL query and replaces them with X or N for numbers.
1329          * It's only slightly flawed. Don't use for anything important.
1330          *
1331          * @param string $sql A SQL Query
1332          *
1333          * @return string
1334          */
1335         protected static function generalizeSQL( $sql ) {
1336                 # This does the same as the regexp below would do, but in such a way
1337                 # as to avoid crashing php on some large strings.
1338                 # $sql = preg_replace( "/'([^\\\\']|\\\\.)*'|\"([^\\\\\"]|\\\\.)*\"/", "'X'", $sql );
1339
1340                 $sql = str_replace( "\\\\", '', $sql );
1341                 $sql = str_replace( "\\'", '', $sql );
1342                 $sql = str_replace( "\\\"", '', $sql );
1343                 $sql = preg_replace( "/'.*'/s", "'X'", $sql );
1344                 $sql = preg_replace( '/".*"/s', "'X'", $sql );
1345
1346                 # All newlines, tabs, etc replaced by single space
1347                 $sql = preg_replace( '/\s+/', ' ', $sql );
1348
1349                 # All numbers => N,
1350                 # except the ones surrounded by characters, e.g. l10n
1351                 $sql = preg_replace( '/-?\d+(,-?\d+)+/s', 'N,...,N', $sql );
1352                 $sql = preg_replace( '/(?<![a-zA-Z])-?\d+(?![a-zA-Z])/s', 'N', $sql );
1353
1354                 return $sql;
1355         }
1356
1357         public function fieldExists( $table, $field, $fname = __METHOD__ ) {
1358                 $info = $this->fieldInfo( $table, $field );
1359
1360                 return (bool)$info;
1361         }
1362
1363         public function indexExists( $table, $index, $fname = __METHOD__ ) {
1364                 if ( !$this->tableExists( $table ) ) {
1365                         return null;
1366                 }
1367
1368                 $info = $this->indexInfo( $table, $index, $fname );
1369                 if ( is_null( $info ) ) {
1370                         return null;
1371                 } else {
1372                         return $info !== false;
1373                 }
1374         }
1375
1376         public function tableExists( $table, $fname = __METHOD__ ) {
1377                 $table = $this->tableName( $table );
1378                 $old = $this->ignoreErrors( true );
1379                 $res = $this->query( "SELECT 1 FROM $table LIMIT 1", $fname );
1380                 $this->ignoreErrors( $old );
1381
1382                 return (bool)$res;
1383         }
1384
1385         public function indexUnique( $table, $index ) {
1386                 $indexInfo = $this->indexInfo( $table, $index );
1387
1388                 if ( !$indexInfo ) {
1389                         return null;
1390                 }
1391
1392                 return !$indexInfo[0]->Non_unique;
1393         }
1394
1395         /**
1396          * Helper for DatabaseBase::insert().
1397          *
1398          * @param array $options
1399          * @return string
1400          */
1401         protected function makeInsertOptions( $options ) {
1402                 return implode( ' ', $options );
1403         }
1404
1405         public function insert( $table, $a, $fname = __METHOD__, $options = [] ) {
1406                 # No rows to insert, easy just return now
1407                 if ( !count( $a ) ) {
1408                         return true;
1409                 }
1410
1411                 $table = $this->tableName( $table );
1412
1413                 if ( !is_array( $options ) ) {
1414                         $options = [ $options ];
1415                 }
1416
1417                 $fh = null;
1418                 if ( isset( $options['fileHandle'] ) ) {
1419                         $fh = $options['fileHandle'];
1420                 }
1421                 $options = $this->makeInsertOptions( $options );
1422
1423                 if ( isset( $a[0] ) && is_array( $a[0] ) ) {
1424                         $multi = true;
1425                         $keys = array_keys( $a[0] );
1426                 } else {
1427                         $multi = false;
1428                         $keys = array_keys( $a );
1429                 }
1430
1431                 $sql = 'INSERT ' . $options .
1432                         " INTO $table (" . implode( ',', $keys ) . ') VALUES ';
1433
1434                 if ( $multi ) {
1435                         $first = true;
1436                         foreach ( $a as $row ) {
1437                                 if ( $first ) {
1438                                         $first = false;
1439                                 } else {
1440                                         $sql .= ',';
1441                                 }
1442                                 $sql .= '(' . $this->makeList( $row ) . ')';
1443                         }
1444                 } else {
1445                         $sql .= '(' . $this->makeList( $a ) . ')';
1446                 }
1447
1448                 if ( $fh !== null && false === fwrite( $fh, $sql ) ) {
1449                         return false;
1450                 } elseif ( $fh !== null ) {
1451                         return true;
1452                 }
1453
1454                 return (bool)$this->query( $sql, $fname );
1455         }
1456
1457         /**
1458          * Make UPDATE options array for DatabaseBase::makeUpdateOptions
1459          *
1460          * @param array $options
1461          * @return array
1462          */
1463         protected function makeUpdateOptionsArray( $options ) {
1464                 if ( !is_array( $options ) ) {
1465                         $options = [ $options ];
1466                 }
1467
1468                 $opts = [];
1469
1470                 if ( in_array( 'IGNORE', $options ) ) {
1471                         $opts[] = 'IGNORE';
1472                 }
1473
1474                 return $opts;
1475         }
1476
1477         /**
1478          * Make UPDATE options for the DatabaseBase::update function
1479          *
1480          * @param array $options The options passed to DatabaseBase::update
1481          * @return string
1482          */
1483         protected function makeUpdateOptions( $options ) {
1484                 $opts = $this->makeUpdateOptionsArray( $options );
1485
1486                 return implode( ' ', $opts );
1487         }
1488
1489         function update( $table, $values, $conds, $fname = __METHOD__, $options = [] ) {
1490                 $table = $this->tableName( $table );
1491                 $opts = $this->makeUpdateOptions( $options );
1492                 $sql = "UPDATE $opts $table SET " . $this->makeList( $values, self::LIST_SET );
1493
1494                 if ( $conds !== [] && $conds !== '*' ) {
1495                         $sql .= " WHERE " . $this->makeList( $conds, self::LIST_AND );
1496                 }
1497
1498                 return $this->query( $sql, $fname );
1499         }
1500
1501         public function makeList( $a, $mode = self::LIST_COMMA ) {
1502                 if ( !is_array( $a ) ) {
1503                         throw new DBUnexpectedError( $this, __METHOD__ . ' called with incorrect parameters' );
1504                 }
1505
1506                 $first = true;
1507                 $list = '';
1508
1509                 foreach ( $a as $field => $value ) {
1510                         if ( !$first ) {
1511                                 if ( $mode == self::LIST_AND ) {
1512                                         $list .= ' AND ';
1513                                 } elseif ( $mode == self::LIST_OR ) {
1514                                         $list .= ' OR ';
1515                                 } else {
1516                                         $list .= ',';
1517                                 }
1518                         } else {
1519                                 $first = false;
1520                         }
1521
1522                         if ( ( $mode == self::LIST_AND || $mode == self::LIST_OR ) && is_numeric( $field ) ) {
1523                                 $list .= "($value)";
1524                         } elseif ( $mode == self::LIST_SET && is_numeric( $field ) ) {
1525                                 $list .= "$value";
1526                         } elseif (
1527                                 ( $mode == self::LIST_AND || $mode == self::LIST_OR ) && is_array( $value )
1528                         ) {
1529                                 // Remove null from array to be handled separately if found
1530                                 $includeNull = false;
1531                                 foreach ( array_keys( $value, null, true ) as $nullKey ) {
1532                                         $includeNull = true;
1533                                         unset( $value[$nullKey] );
1534                                 }
1535                                 if ( count( $value ) == 0 && !$includeNull ) {
1536                                         throw new InvalidArgumentException(
1537                                                 __METHOD__ . ": empty input for field $field" );
1538                                 } elseif ( count( $value ) == 0 ) {
1539                                         // only check if $field is null
1540                                         $list .= "$field IS NULL";
1541                                 } else {
1542                                         // IN clause contains at least one valid element
1543                                         if ( $includeNull ) {
1544                                                 // Group subconditions to ensure correct precedence
1545                                                 $list .= '(';
1546                                         }
1547                                         if ( count( $value ) == 1 ) {
1548                                                 // Special-case single values, as IN isn't terribly efficient
1549                                                 // Don't necessarily assume the single key is 0; we don't
1550                                                 // enforce linear numeric ordering on other arrays here.
1551                                                 $value = array_values( $value )[0];
1552                                                 $list .= $field . " = " . $this->addQuotes( $value );
1553                                         } else {
1554                                                 $list .= $field . " IN (" . $this->makeList( $value ) . ") ";
1555                                         }
1556                                         // if null present in array, append IS NULL
1557                                         if ( $includeNull ) {
1558                                                 $list .= " OR $field IS NULL)";
1559                                         }
1560                                 }
1561                         } elseif ( $value === null ) {
1562                                 if ( $mode == self::LIST_AND || $mode == self::LIST_OR ) {
1563                                         $list .= "$field IS ";
1564                                 } elseif ( $mode == self::LIST_SET ) {
1565                                         $list .= "$field = ";
1566                                 }
1567                                 $list .= 'NULL';
1568                         } else {
1569                                 if (
1570                                         $mode == self::LIST_AND || $mode == self::LIST_OR || $mode == self::LIST_SET
1571                                 ) {
1572                                         $list .= "$field = ";
1573                                 }
1574                                 $list .= $mode == self::LIST_NAMES ? $value : $this->addQuotes( $value );
1575                         }
1576                 }
1577
1578                 return $list;
1579         }
1580
1581         public function makeWhereFrom2d( $data, $baseKey, $subKey ) {
1582                 $conds = [];
1583
1584                 foreach ( $data as $base => $sub ) {
1585                         if ( count( $sub ) ) {
1586                                 $conds[] = $this->makeList(
1587                                         [ $baseKey => $base, $subKey => array_keys( $sub ) ],
1588                                         self::LIST_AND );
1589                         }
1590                 }
1591
1592                 if ( $conds ) {
1593                         return $this->makeList( $conds, self::LIST_OR );
1594                 } else {
1595                         // Nothing to search for...
1596                         return false;
1597                 }
1598         }
1599
1600         /**
1601          * Return aggregated value alias
1602          *
1603          * @param array $valuedata
1604          * @param string $valuename
1605          *
1606          * @return string
1607          */
1608         public function aggregateValue( $valuedata, $valuename = 'value' ) {
1609                 return $valuename;
1610         }
1611
1612         public function bitNot( $field ) {
1613                 return "(~$field)";
1614         }
1615
1616         public function bitAnd( $fieldLeft, $fieldRight ) {
1617                 return "($fieldLeft & $fieldRight)";
1618         }
1619
1620         public function bitOr( $fieldLeft, $fieldRight ) {
1621                 return "($fieldLeft | $fieldRight)";
1622         }
1623
1624         public function buildConcat( $stringList ) {
1625                 return 'CONCAT(' . implode( ',', $stringList ) . ')';
1626         }
1627
1628         public function buildGroupConcatField(
1629                 $delim, $table, $field, $conds = '', $join_conds = []
1630         ) {
1631                 $fld = "GROUP_CONCAT($field SEPARATOR " . $this->addQuotes( $delim ) . ')';
1632
1633                 return '(' . $this->selectSQLText( $table, $fld, $conds, null, [], $join_conds ) . ')';
1634         }
1635
1636         /**
1637          * @param string $field Field or column to cast
1638          * @return string
1639          * @since 1.28
1640          */
1641         public function buildStringCast( $field ) {
1642                 return $field;
1643         }
1644
1645         public function selectDB( $db ) {
1646                 # Stub. Shouldn't cause serious problems if it's not overridden, but
1647                 # if your database engine supports a concept similar to MySQL's
1648                 # databases you may as well.
1649                 $this->mDBname = $db;
1650
1651                 return true;
1652         }
1653
1654         public function getDBname() {
1655                 return $this->mDBname;
1656         }
1657
1658         public function getServer() {
1659                 return $this->mServer;
1660         }
1661
1662         /**
1663          * Format a table name ready for use in constructing an SQL query
1664          *
1665          * This does two important things: it quotes the table names to clean them up,
1666          * and it adds a table prefix if only given a table name with no quotes.
1667          *
1668          * All functions of this object which require a table name call this function
1669          * themselves. Pass the canonical name to such functions. This is only needed
1670          * when calling query() directly.
1671          *
1672          * @note This function does not sanitize user input. It is not safe to use
1673          *   this function to escape user input.
1674          * @param string $name Database table name
1675          * @param string $format One of:
1676          *   quoted - Automatically pass the table name through addIdentifierQuotes()
1677          *            so that it can be used in a query.
1678          *   raw - Do not add identifier quotes to the table name
1679          * @return string Full database name
1680          */
1681         public function tableName( $name, $format = 'quoted' ) {
1682                 # Skip the entire process when we have a string quoted on both ends.
1683                 # Note that we check the end so that we will still quote any use of
1684                 # use of `database`.table. But won't break things if someone wants
1685                 # to query a database table with a dot in the name.
1686                 if ( $this->isQuotedIdentifier( $name ) ) {
1687                         return $name;
1688                 }
1689
1690                 # Lets test for any bits of text that should never show up in a table
1691                 # name. Basically anything like JOIN or ON which are actually part of
1692                 # SQL queries, but may end up inside of the table value to combine
1693                 # sql. Such as how the API is doing.
1694                 # Note that we use a whitespace test rather than a \b test to avoid
1695                 # any remote case where a word like on may be inside of a table name
1696                 # surrounded by symbols which may be considered word breaks.
1697                 if ( preg_match( '/(^|\s)(DISTINCT|JOIN|ON|AS)(\s|$)/i', $name ) !== 0 ) {
1698                         return $name;
1699                 }
1700
1701                 # Split database and table into proper variables.
1702                 # We reverse the explode so that database.table and table both output
1703                 # the correct table.
1704                 $dbDetails = explode( '.', $name, 3 );
1705                 if ( count( $dbDetails ) == 3 ) {
1706                         list( $database, $schema, $table ) = $dbDetails;
1707                         # We don't want any prefix added in this case
1708                         $prefix = '';
1709                 } elseif ( count( $dbDetails ) == 2 ) {
1710                         list( $database, $table ) = $dbDetails;
1711                         # We don't want any prefix added in this case
1712                         # In dbs that support it, $database may actually be the schema
1713                         # but that doesn't affect any of the functionality here
1714                         $prefix = '';
1715                         $schema = '';
1716                 } else {
1717                         list( $table ) = $dbDetails;
1718                         if ( isset( $this->tableAliases[$table] ) ) {
1719                                 $database = $this->tableAliases[$table]['dbname'];
1720                                 $schema = is_string( $this->tableAliases[$table]['schema'] )
1721                                         ? $this->tableAliases[$table]['schema']
1722                                         : $this->mSchema;
1723                                 $prefix = is_string( $this->tableAliases[$table]['prefix'] )
1724                                         ? $this->tableAliases[$table]['prefix']
1725                                         : $this->mTablePrefix;
1726                         } else {
1727                                 $database = '';
1728                                 $schema = $this->mSchema; # Default schema
1729                                 $prefix = $this->mTablePrefix; # Default prefix
1730                         }
1731                 }
1732
1733                 # Quote $table and apply the prefix if not quoted.
1734                 # $tableName might be empty if this is called from Database::replaceVars()
1735                 $tableName = "{$prefix}{$table}";
1736                 if ( $format == 'quoted'
1737                         && !$this->isQuotedIdentifier( $tableName ) && $tableName !== ''
1738                 ) {
1739                         $tableName = $this->addIdentifierQuotes( $tableName );
1740                 }
1741
1742                 # Quote $schema and merge it with the table name if needed
1743                 if ( strlen( $schema ) ) {
1744                         if ( $format == 'quoted' && !$this->isQuotedIdentifier( $schema ) ) {
1745                                 $schema = $this->addIdentifierQuotes( $schema );
1746                         }
1747                         $tableName = $schema . '.' . $tableName;
1748                 }
1749
1750                 # Quote $database and merge it with the table name if needed
1751                 if ( $database !== '' ) {
1752                         if ( $format == 'quoted' && !$this->isQuotedIdentifier( $database ) ) {
1753                                 $database = $this->addIdentifierQuotes( $database );
1754                         }
1755                         $tableName = $database . '.' . $tableName;
1756                 }
1757
1758                 return $tableName;
1759         }
1760
1761         /**
1762          * Fetch a number of table names into an array
1763          * This is handy when you need to construct SQL for joins
1764          *
1765          * Example:
1766          * extract( $dbr->tableNames( 'user', 'watchlist' ) );
1767          * $sql = "SELECT wl_namespace,wl_title FROM $watchlist,$user
1768          *         WHERE wl_user=user_id AND wl_user=$nameWithQuotes";
1769          *
1770          * @return array
1771          */
1772         public function tableNames() {
1773                 $inArray = func_get_args();
1774                 $retVal = [];
1775
1776                 foreach ( $inArray as $name ) {
1777                         $retVal[$name] = $this->tableName( $name );
1778                 }
1779
1780                 return $retVal;
1781         }
1782
1783         /**
1784          * Fetch a number of table names into an zero-indexed numerical array
1785          * This is handy when you need to construct SQL for joins
1786          *
1787          * Example:
1788          * list( $user, $watchlist ) = $dbr->tableNamesN( 'user', 'watchlist' );
1789          * $sql = "SELECT wl_namespace,wl_title FROM $watchlist,$user
1790          *         WHERE wl_user=user_id AND wl_user=$nameWithQuotes";
1791          *
1792          * @return array
1793          */
1794         public function tableNamesN() {
1795                 $inArray = func_get_args();
1796                 $retVal = [];
1797
1798                 foreach ( $inArray as $name ) {
1799                         $retVal[] = $this->tableName( $name );
1800                 }
1801
1802                 return $retVal;
1803         }
1804
1805         /**
1806          * Get an aliased table name
1807          * e.g. tableName AS newTableName
1808          *
1809          * @param string $name Table name, see tableName()
1810          * @param string|bool $alias Alias (optional)
1811          * @return string SQL name for aliased table. Will not alias a table to its own name
1812          */
1813         public function tableNameWithAlias( $name, $alias = false ) {
1814                 if ( !$alias || $alias == $name ) {
1815                         return $this->tableName( $name );
1816                 } else {
1817                         return $this->tableName( $name ) . ' ' . $this->addIdentifierQuotes( $alias );
1818                 }
1819         }
1820
1821         /**
1822          * Gets an array of aliased table names
1823          *
1824          * @param array $tables [ [alias] => table ]
1825          * @return string[] See tableNameWithAlias()
1826          */
1827         public function tableNamesWithAlias( $tables ) {
1828                 $retval = [];
1829                 foreach ( $tables as $alias => $table ) {
1830                         if ( is_numeric( $alias ) ) {
1831                                 $alias = $table;
1832                         }
1833                         $retval[] = $this->tableNameWithAlias( $table, $alias );
1834                 }
1835
1836                 return $retval;
1837         }
1838
1839         /**
1840          * Get an aliased field name
1841          * e.g. fieldName AS newFieldName
1842          *
1843          * @param string $name Field name
1844          * @param string|bool $alias Alias (optional)
1845          * @return string SQL name for aliased field. Will not alias a field to its own name
1846          */
1847         public function fieldNameWithAlias( $name, $alias = false ) {
1848                 if ( !$alias || (string)$alias === (string)$name ) {
1849                         return $name;
1850                 } else {
1851                         return $name . ' AS ' . $this->addIdentifierQuotes( $alias ); // PostgreSQL needs AS
1852                 }
1853         }
1854
1855         /**
1856          * Gets an array of aliased field names
1857          *
1858          * @param array $fields [ [alias] => field ]
1859          * @return string[] See fieldNameWithAlias()
1860          */
1861         public function fieldNamesWithAlias( $fields ) {
1862                 $retval = [];
1863                 foreach ( $fields as $alias => $field ) {
1864                         if ( is_numeric( $alias ) ) {
1865                                 $alias = $field;
1866                         }
1867                         $retval[] = $this->fieldNameWithAlias( $field, $alias );
1868                 }
1869
1870                 return $retval;
1871         }
1872
1873         /**
1874          * Get the aliased table name clause for a FROM clause
1875          * which might have a JOIN and/or USE INDEX or IGNORE INDEX clause
1876          *
1877          * @param array $tables ( [alias] => table )
1878          * @param array $use_index Same as for select()
1879          * @param array $ignore_index Same as for select()
1880          * @param array $join_conds Same as for select()
1881          * @return string
1882          */
1883         protected function tableNamesWithIndexClauseOrJOIN(
1884                 $tables, $use_index = [], $ignore_index = [], $join_conds = []
1885         ) {
1886                 $ret = [];
1887                 $retJOIN = [];
1888                 $use_index = (array)$use_index;
1889                 $ignore_index = (array)$ignore_index;
1890                 $join_conds = (array)$join_conds;
1891
1892                 foreach ( $tables as $alias => $table ) {
1893                         if ( !is_string( $alias ) ) {
1894                                 // No alias? Set it equal to the table name
1895                                 $alias = $table;
1896                         }
1897                         // Is there a JOIN clause for this table?
1898                         if ( isset( $join_conds[$alias] ) ) {
1899                                 list( $joinType, $conds ) = $join_conds[$alias];
1900                                 $tableClause = $joinType;
1901                                 $tableClause .= ' ' . $this->tableNameWithAlias( $table, $alias );
1902                                 if ( isset( $use_index[$alias] ) ) { // has USE INDEX?
1903                                         $use = $this->useIndexClause( implode( ',', (array)$use_index[$alias] ) );
1904                                         if ( $use != '' ) {
1905                                                 $tableClause .= ' ' . $use;
1906                                         }
1907                                 }
1908                                 if ( isset( $ignore_index[$alias] ) ) { // has IGNORE INDEX?
1909                                         $ignore = $this->ignoreIndexClause( implode( ',', (array)$ignore_index[$alias] ) );
1910                                         if ( $ignore != '' ) {
1911                                                 $tableClause .= ' ' . $ignore;
1912                                         }
1913                                 }
1914                                 $on = $this->makeList( (array)$conds, self::LIST_AND );
1915                                 if ( $on != '' ) {
1916                                         $tableClause .= ' ON (' . $on . ')';
1917                                 }
1918
1919                                 $retJOIN[] = $tableClause;
1920                         } elseif ( isset( $use_index[$alias] ) ) {
1921                                 // Is there an INDEX clause for this table?
1922                                 $tableClause = $this->tableNameWithAlias( $table, $alias );
1923                                 $tableClause .= ' ' . $this->useIndexClause(
1924                                                 implode( ',', (array)$use_index[$alias] )
1925                                         );
1926
1927                                 $ret[] = $tableClause;
1928                         } elseif ( isset( $ignore_index[$alias] ) ) {
1929                                 // Is there an INDEX clause for this table?
1930                                 $tableClause = $this->tableNameWithAlias( $table, $alias );
1931                                 $tableClause .= ' ' . $this->ignoreIndexClause(
1932                                                 implode( ',', (array)$ignore_index[$alias] )
1933                                         );
1934
1935                                 $ret[] = $tableClause;
1936                         } else {
1937                                 $tableClause = $this->tableNameWithAlias( $table, $alias );
1938
1939                                 $ret[] = $tableClause;
1940                         }
1941                 }
1942
1943                 // We can't separate explicit JOIN clauses with ',', use ' ' for those
1944                 $implicitJoins = !empty( $ret ) ? implode( ',', $ret ) : "";
1945                 $explicitJoins = !empty( $retJOIN ) ? implode( ' ', $retJOIN ) : "";
1946
1947                 // Compile our final table clause
1948                 return implode( ' ', [ $implicitJoins, $explicitJoins ] );
1949         }
1950
1951         /**
1952          * Get the name of an index in a given table.
1953          *
1954          * @param string $index
1955          * @return string
1956          */
1957         protected function indexName( $index ) {
1958                 // Backwards-compatibility hack
1959                 $renamed = [
1960                         'ar_usertext_timestamp' => 'usertext_timestamp',
1961                         'un_user_id' => 'user_id',
1962                         'un_user_ip' => 'user_ip',
1963                 ];
1964
1965                 if ( isset( $renamed[$index] ) ) {
1966                         return $renamed[$index];
1967                 } else {
1968                         return $index;
1969                 }
1970         }
1971
1972         public function addQuotes( $s ) {
1973                 if ( $s instanceof Blob ) {
1974                         $s = $s->fetch();
1975                 }
1976                 if ( $s === null ) {
1977                         return 'NULL';
1978                 } else {
1979                         # This will also quote numeric values. This should be harmless,
1980                         # and protects against weird problems that occur when they really
1981                         # _are_ strings such as article titles and string->number->string
1982                         # conversion is not 1:1.
1983                         return "'" . $this->strencode( $s ) . "'";
1984                 }
1985         }
1986
1987         /**
1988          * Quotes an identifier using `backticks` or "double quotes" depending on the database type.
1989          * MySQL uses `backticks` while basically everything else uses double quotes.
1990          * Since MySQL is the odd one out here the double quotes are our generic
1991          * and we implement backticks in DatabaseMysql.
1992          *
1993          * @param string $s
1994          * @return string
1995          */
1996         public function addIdentifierQuotes( $s ) {
1997                 return '"' . str_replace( '"', '""', $s ) . '"';
1998         }
1999
2000         /**
2001          * Returns if the given identifier looks quoted or not according to
2002          * the database convention for quoting identifiers .
2003          *
2004          * @note Do not use this to determine if untrusted input is safe.
2005          *   A malicious user can trick this function.
2006          * @param string $name
2007          * @return bool
2008          */
2009         public function isQuotedIdentifier( $name ) {
2010                 return $name[0] == '"' && substr( $name, -1, 1 ) == '"';
2011         }
2012
2013         /**
2014          * @param string $s
2015          * @return string
2016          */
2017         protected function escapeLikeInternal( $s ) {
2018                 return addcslashes( $s, '\%_' );
2019         }
2020
2021         public function buildLike() {
2022                 $params = func_get_args();
2023
2024                 if ( count( $params ) > 0 && is_array( $params[0] ) ) {
2025                         $params = $params[0];
2026                 }
2027
2028                 $s = '';
2029
2030                 foreach ( $params as $value ) {
2031                         if ( $value instanceof LikeMatch ) {
2032                                 $s .= $value->toString();
2033                         } else {
2034                                 $s .= $this->escapeLikeInternal( $value );
2035                         }
2036                 }
2037
2038                 return " LIKE {$this->addQuotes( $s )} ";
2039         }
2040
2041         public function anyChar() {
2042                 return new LikeMatch( '_' );
2043         }
2044
2045         public function anyString() {
2046                 return new LikeMatch( '%' );
2047         }
2048
2049         public function nextSequenceValue( $seqName ) {
2050                 return null;
2051         }
2052
2053         /**
2054          * USE INDEX clause. Unlikely to be useful for anything but MySQL. This
2055          * is only needed because a) MySQL must be as efficient as possible due to
2056          * its use on Wikipedia, and b) MySQL 4.0 is kind of dumb sometimes about
2057          * which index to pick. Anyway, other databases might have different
2058          * indexes on a given table. So don't bother overriding this unless you're
2059          * MySQL.
2060          * @param string $index
2061          * @return string
2062          */
2063         public function useIndexClause( $index ) {
2064                 return '';
2065         }
2066
2067         /**
2068          * IGNORE INDEX clause. Unlikely to be useful for anything but MySQL. This
2069          * is only needed because a) MySQL must be as efficient as possible due to
2070          * its use on Wikipedia, and b) MySQL 4.0 is kind of dumb sometimes about
2071          * which index to pick. Anyway, other databases might have different
2072          * indexes on a given table. So don't bother overriding this unless you're
2073          * MySQL.
2074          * @param string $index
2075          * @return string
2076          */
2077         public function ignoreIndexClause( $index ) {
2078                 return '';
2079         }
2080
2081         public function replace( $table, $uniqueIndexes, $rows, $fname = __METHOD__ ) {
2082                 $quotedTable = $this->tableName( $table );
2083
2084                 if ( count( $rows ) == 0 ) {
2085                         return;
2086                 }
2087
2088                 # Single row case
2089                 if ( !is_array( reset( $rows ) ) ) {
2090                         $rows = [ $rows ];
2091                 }
2092
2093                 // @FXIME: this is not atomic, but a trx would break affectedRows()
2094                 foreach ( $rows as $row ) {
2095                         # Delete rows which collide
2096                         if ( $uniqueIndexes ) {
2097                                 $sql = "DELETE FROM $quotedTable WHERE ";
2098                                 $first = true;
2099                                 foreach ( $uniqueIndexes as $index ) {
2100                                         if ( $first ) {
2101                                                 $first = false;
2102                                                 $sql .= '( ';
2103                                         } else {
2104                                                 $sql .= ' ) OR ( ';
2105                                         }
2106                                         if ( is_array( $index ) ) {
2107                                                 $first2 = true;
2108                                                 foreach ( $index as $col ) {
2109                                                         if ( $first2 ) {
2110                                                                 $first2 = false;
2111                                                         } else {
2112                                                                 $sql .= ' AND ';
2113                                                         }
2114                                                         $sql .= $col . '=' . $this->addQuotes( $row[$col] );
2115                                                 }
2116                                         } else {
2117                                                 $sql .= $index . '=' . $this->addQuotes( $row[$index] );
2118                                         }
2119                                 }
2120                                 $sql .= ' )';
2121                                 $this->query( $sql, $fname );
2122                         }
2123
2124                         # Now insert the row
2125                         $this->insert( $table, $row, $fname );
2126                 }
2127         }
2128
2129         /**
2130          * REPLACE query wrapper for MySQL and SQLite, which have a native REPLACE
2131          * statement.
2132          *
2133          * @param string $table Table name
2134          * @param array|string $rows Row(s) to insert
2135          * @param string $fname Caller function name
2136          *
2137          * @return ResultWrapper
2138          */
2139         protected function nativeReplace( $table, $rows, $fname ) {
2140                 $table = $this->tableName( $table );
2141
2142                 # Single row case
2143                 if ( !is_array( reset( $rows ) ) ) {
2144                         $rows = [ $rows ];
2145                 }
2146
2147                 $sql = "REPLACE INTO $table (" . implode( ',', array_keys( $rows[0] ) ) . ') VALUES ';
2148                 $first = true;
2149
2150                 foreach ( $rows as $row ) {
2151                         if ( $first ) {
2152                                 $first = false;
2153                         } else {
2154                                 $sql .= ',';
2155                         }
2156
2157                         $sql .= '(' . $this->makeList( $row ) . ')';
2158                 }
2159
2160                 return $this->query( $sql, $fname );
2161         }
2162
2163         public function upsert( $table, array $rows, array $uniqueIndexes, array $set,
2164                 $fname = __METHOD__
2165         ) {
2166                 if ( !count( $rows ) ) {
2167                         return true; // nothing to do
2168                 }
2169
2170                 if ( !is_array( reset( $rows ) ) ) {
2171                         $rows = [ $rows ];
2172                 }
2173
2174                 if ( count( $uniqueIndexes ) ) {
2175                         $clauses = []; // list WHERE clauses that each identify a single row
2176                         foreach ( $rows as $row ) {
2177                                 foreach ( $uniqueIndexes as $index ) {
2178                                         $index = is_array( $index ) ? $index : [ $index ]; // columns
2179                                         $rowKey = []; // unique key to this row
2180                                         foreach ( $index as $column ) {
2181                                                 $rowKey[$column] = $row[$column];
2182                                         }
2183                                         $clauses[] = $this->makeList( $rowKey, self::LIST_AND );
2184                                 }
2185                         }
2186                         $where = [ $this->makeList( $clauses, self::LIST_OR ) ];
2187                 } else {
2188                         $where = false;
2189                 }
2190
2191                 $useTrx = !$this->mTrxLevel;
2192                 if ( $useTrx ) {
2193                         $this->begin( $fname, self::TRANSACTION_INTERNAL );
2194                 }
2195                 try {
2196                         # Update any existing conflicting row(s)
2197                         if ( $where !== false ) {
2198                                 $ok = $this->update( $table, $set, $where, $fname );
2199                         } else {
2200                                 $ok = true;
2201                         }
2202                         # Now insert any non-conflicting row(s)
2203                         $ok = $this->insert( $table, $rows, $fname, [ 'IGNORE' ] ) && $ok;
2204                 } catch ( Exception $e ) {
2205                         if ( $useTrx ) {
2206                                 $this->rollback( $fname, self::FLUSHING_INTERNAL );
2207                         }
2208                         throw $e;
2209                 }
2210                 if ( $useTrx ) {
2211                         $this->commit( $fname, self::FLUSHING_INTERNAL );
2212                 }
2213
2214                 return $ok;
2215         }
2216
2217         public function deleteJoin( $delTable, $joinTable, $delVar, $joinVar, $conds,
2218                 $fname = __METHOD__
2219         ) {
2220                 if ( !$conds ) {
2221                         throw new DBUnexpectedError( $this, __METHOD__ . ' called with empty $conds' );
2222                 }
2223
2224                 $delTable = $this->tableName( $delTable );
2225                 $joinTable = $this->tableName( $joinTable );
2226                 $sql = "DELETE FROM $delTable WHERE $delVar IN (SELECT $joinVar FROM $joinTable ";
2227                 if ( $conds != '*' ) {
2228                         $sql .= 'WHERE ' . $this->makeList( $conds, self::LIST_AND );
2229                 }
2230                 $sql .= ')';
2231
2232                 $this->query( $sql, $fname );
2233         }
2234
2235         /**
2236          * Returns the size of a text field, or -1 for "unlimited"
2237          *
2238          * @param string $table
2239          * @param string $field
2240          * @return int
2241          */
2242         public function textFieldSize( $table, $field ) {
2243                 $table = $this->tableName( $table );
2244                 $sql = "SHOW COLUMNS FROM $table LIKE \"$field\";";
2245                 $res = $this->query( $sql, __METHOD__ );
2246                 $row = $this->fetchObject( $res );
2247
2248                 $m = [];
2249
2250                 if ( preg_match( '/\((.*)\)/', $row->Type, $m ) ) {
2251                         $size = $m[1];
2252                 } else {
2253                         $size = -1;
2254                 }
2255
2256                 return $size;
2257         }
2258
2259         public function delete( $table, $conds, $fname = __METHOD__ ) {
2260                 if ( !$conds ) {
2261                         throw new DBUnexpectedError( $this, __METHOD__ . ' called with no conditions' );
2262                 }
2263
2264                 $table = $this->tableName( $table );
2265                 $sql = "DELETE FROM $table";
2266
2267                 if ( $conds != '*' ) {
2268                         if ( is_array( $conds ) ) {
2269                                 $conds = $this->makeList( $conds, self::LIST_AND );
2270                         }
2271                         $sql .= ' WHERE ' . $conds;
2272                 }
2273
2274                 return $this->query( $sql, $fname );
2275         }
2276
2277         public function insertSelect(
2278                 $destTable, $srcTable, $varMap, $conds,
2279                 $fname = __METHOD__, $insertOptions = [], $selectOptions = []
2280         ) {
2281                 if ( $this->cliMode ) {
2282                         // For massive migrations with downtime, we don't want to select everything
2283                         // into memory and OOM, so do all this native on the server side if possible.
2284                         return $this->nativeInsertSelect(
2285                                 $destTable,
2286                                 $srcTable,
2287                                 $varMap,
2288                                 $conds,
2289                                 $fname,
2290                                 $insertOptions,
2291                                 $selectOptions
2292                         );
2293                 }
2294
2295                 // For web requests, do a locking SELECT and then INSERT. This puts the SELECT burden
2296                 // on only the master (without needing row-based-replication). It also makes it easy to
2297                 // know how big the INSERT is going to be.
2298                 $fields = [];
2299                 foreach ( $varMap as $dstColumn => $sourceColumnOrSql ) {
2300                         $fields[] = $this->fieldNameWithAlias( $sourceColumnOrSql, $dstColumn );
2301                 }
2302                 $selectOptions[] = 'FOR UPDATE';
2303                 $res = $this->select( $srcTable, implode( ',', $fields ), $conds, $fname, $selectOptions );
2304                 if ( !$res ) {
2305                         return false;
2306                 }
2307
2308                 $rows = [];
2309                 foreach ( $res as $row ) {
2310                         $rows[] = (array)$row;
2311                 }
2312
2313                 return $this->insert( $destTable, $rows, $fname, $insertOptions );
2314         }
2315
2316         public function nativeInsertSelect( $destTable, $srcTable, $varMap, $conds,
2317                 $fname = __METHOD__,
2318                 $insertOptions = [], $selectOptions = []
2319         ) {
2320                 $destTable = $this->tableName( $destTable );
2321
2322                 if ( !is_array( $insertOptions ) ) {
2323                         $insertOptions = [ $insertOptions ];
2324                 }
2325
2326                 $insertOptions = $this->makeInsertOptions( $insertOptions );
2327
2328                 if ( !is_array( $selectOptions ) ) {
2329                         $selectOptions = [ $selectOptions ];
2330                 }
2331
2332                 list( $startOpts, $useIndex, $tailOpts, $ignoreIndex ) = $this->makeSelectOptions(
2333                         $selectOptions );
2334
2335                 if ( is_array( $srcTable ) ) {
2336                         $srcTable = implode( ',', array_map( [ &$this, 'tableName' ], $srcTable ) );
2337                 } else {
2338                         $srcTable = $this->tableName( $srcTable );
2339                 }
2340
2341                 $sql = "INSERT $insertOptions INTO $destTable (" . implode( ',', array_keys( $varMap ) ) . ')' .
2342                         " SELECT $startOpts " . implode( ',', $varMap ) .
2343                         " FROM $srcTable $useIndex $ignoreIndex ";
2344
2345                 if ( $conds != '*' ) {
2346                         if ( is_array( $conds ) ) {
2347                                 $conds = $this->makeList( $conds, self::LIST_AND );
2348                         }
2349                         $sql .= " WHERE $conds";
2350                 }
2351
2352                 $sql .= " $tailOpts";
2353
2354                 return $this->query( $sql, $fname );
2355         }
2356
2357         /**
2358          * Construct a LIMIT query with optional offset. This is used for query
2359          * pages. The SQL should be adjusted so that only the first $limit rows
2360          * are returned. If $offset is provided as well, then the first $offset
2361          * rows should be discarded, and the next $limit rows should be returned.
2362          * If the result of the query is not ordered, then the rows to be returned
2363          * are theoretically arbitrary.
2364          *
2365          * $sql is expected to be a SELECT, if that makes a difference.
2366          *
2367          * The version provided by default works in MySQL and SQLite. It will very
2368          * likely need to be overridden for most other DBMSes.
2369          *
2370          * @param string $sql SQL query we will append the limit too
2371          * @param int $limit The SQL limit
2372          * @param int|bool $offset The SQL offset (default false)
2373          * @throws DBUnexpectedError
2374          * @return string
2375          */
2376         public function limitResult( $sql, $limit, $offset = false ) {
2377                 if ( !is_numeric( $limit ) ) {
2378                         throw new DBUnexpectedError( $this, "Invalid non-numeric limit passed to limitResult()\n" );
2379                 }
2380
2381                 return "$sql LIMIT "
2382                 . ( ( is_numeric( $offset ) && $offset != 0 ) ? "{$offset}," : "" )
2383                 . "{$limit} ";
2384         }
2385
2386         public function unionSupportsOrderAndLimit() {
2387                 return true; // True for almost every DB supported
2388         }
2389
2390         public function unionQueries( $sqls, $all ) {
2391                 $glue = $all ? ') UNION ALL (' : ') UNION (';
2392
2393                 return '(' . implode( $glue, $sqls ) . ')';
2394         }
2395
2396         public function conditional( $cond, $trueVal, $falseVal ) {
2397                 if ( is_array( $cond ) ) {
2398                         $cond = $this->makeList( $cond, self::LIST_AND );
2399                 }
2400
2401                 return " (CASE WHEN $cond THEN $trueVal ELSE $falseVal END) ";
2402         }
2403
2404         public function strreplace( $orig, $old, $new ) {
2405                 return "REPLACE({$orig}, {$old}, {$new})";
2406         }
2407
2408         public function getServerUptime() {
2409                 return 0;
2410         }
2411
2412         public function wasDeadlock() {
2413                 return false;
2414         }
2415
2416         public function wasLockTimeout() {
2417                 return false;
2418         }
2419
2420         public function wasErrorReissuable() {
2421                 return false;
2422         }
2423
2424         public function wasReadOnlyError() {
2425                 return false;
2426         }
2427
2428         /**
2429          * Determines if the given query error was a connection drop
2430          * STUB
2431          *
2432          * @param integer|string $errno
2433          * @return bool
2434          */
2435         public function wasConnectionError( $errno ) {
2436                 return false;
2437         }
2438
2439         /**
2440          * Perform a deadlock-prone transaction.
2441          *
2442          * This function invokes a callback function to perform a set of write
2443          * queries. If a deadlock occurs during the processing, the transaction
2444          * will be rolled back and the callback function will be called again.
2445          *
2446          * Avoid using this method outside of Job or Maintenance classes.
2447          *
2448          * Usage:
2449          *   $dbw->deadlockLoop( callback, ... );
2450          *
2451          * Extra arguments are passed through to the specified callback function.
2452          * This method requires that no transactions are already active to avoid
2453          * causing premature commits or exceptions.
2454          *
2455          * Returns whatever the callback function returned on its successful,
2456          * iteration, or false on error, for example if the retry limit was
2457          * reached.
2458          *
2459          * @return mixed
2460          * @throws DBUnexpectedError
2461          * @throws Exception
2462          */
2463         public function deadlockLoop() {
2464                 $args = func_get_args();
2465                 $function = array_shift( $args );
2466                 $tries = self::DEADLOCK_TRIES;
2467
2468                 $this->begin( __METHOD__ );
2469
2470                 $retVal = null;
2471                 /** @var Exception $e */
2472                 $e = null;
2473                 do {
2474                         try {
2475                                 $retVal = call_user_func_array( $function, $args );
2476                                 break;
2477                         } catch ( DBQueryError $e ) {
2478                                 if ( $this->wasDeadlock() ) {
2479                                         // Retry after a randomized delay
2480                                         usleep( mt_rand( self::DEADLOCK_DELAY_MIN, self::DEADLOCK_DELAY_MAX ) );
2481                                 } else {
2482                                         // Throw the error back up
2483                                         throw $e;
2484                                 }
2485                         }
2486                 } while ( --$tries > 0 );
2487
2488                 if ( $tries <= 0 ) {
2489                         // Too many deadlocks; give up
2490                         $this->rollback( __METHOD__ );
2491                         throw $e;
2492                 } else {
2493                         $this->commit( __METHOD__ );
2494
2495                         return $retVal;
2496                 }
2497         }
2498
2499         public function masterPosWait( DBMasterPos $pos, $timeout ) {
2500                 # Real waits are implemented in the subclass.
2501                 return 0;
2502         }
2503
2504         public function getSlavePos() {
2505                 # Stub
2506                 return false;
2507         }
2508
2509         public function getMasterPos() {
2510                 # Stub
2511                 return false;
2512         }
2513
2514         public function serverIsReadOnly() {
2515                 return false;
2516         }
2517
2518         final public function onTransactionResolution( callable $callback, $fname = __METHOD__ ) {
2519                 if ( !$this->mTrxLevel ) {
2520                         throw new DBUnexpectedError( $this, "No transaction is active." );
2521                 }
2522                 $this->mTrxEndCallbacks[] = [ $callback, $fname ];
2523         }
2524
2525         final public function onTransactionIdle( callable $callback, $fname = __METHOD__ ) {
2526                 $this->mTrxIdleCallbacks[] = [ $callback, $fname ];
2527                 if ( !$this->mTrxLevel ) {
2528                         $this->runOnTransactionIdleCallbacks( self::TRIGGER_IDLE );
2529                 }
2530         }
2531
2532         final public function onTransactionPreCommitOrIdle( callable $callback, $fname = __METHOD__ ) {
2533                 if ( $this->mTrxLevel ) {
2534                         $this->mTrxPreCommitCallbacks[] = [ $callback, $fname ];
2535                 } else {
2536                         // If no transaction is active, then make one for this callback
2537                         $this->startAtomic( __METHOD__ );
2538                         try {
2539                                 call_user_func( $callback );
2540                                 $this->endAtomic( __METHOD__ );
2541                         } catch ( Exception $e ) {
2542                                 $this->rollback( __METHOD__, self::FLUSHING_INTERNAL );
2543                                 throw $e;
2544                         }
2545                 }
2546         }
2547
2548         final public function setTransactionListener( $name, callable $callback = null ) {
2549                 if ( $callback ) {
2550                         $this->mTrxRecurringCallbacks[$name] = $callback;
2551                 } else {
2552                         unset( $this->mTrxRecurringCallbacks[$name] );
2553                 }
2554         }
2555
2556         /**
2557          * Whether to disable running of post-COMMIT/ROLLBACK callbacks
2558          *
2559          * This method should not be used outside of Database/LoadBalancer
2560          *
2561          * @param bool $suppress
2562          * @since 1.28
2563          */
2564         final public function setTrxEndCallbackSuppression( $suppress ) {
2565                 $this->mTrxEndCallbacksSuppressed = $suppress;
2566         }
2567
2568         /**
2569          * Actually run and consume any "on transaction idle/resolution" callbacks.
2570          *
2571          * This method should not be used outside of Database/LoadBalancer
2572          *
2573          * @param integer $trigger IDatabase::TRIGGER_* constant
2574          * @since 1.20
2575          * @throws Exception
2576          */
2577         public function runOnTransactionIdleCallbacks( $trigger ) {
2578                 if ( $this->mTrxEndCallbacksSuppressed ) {
2579                         return;
2580                 }
2581
2582                 $autoTrx = $this->getFlag( DBO_TRX ); // automatic begin() enabled?
2583                 /** @var Exception $e */
2584                 $e = null; // first exception
2585                 do { // callbacks may add callbacks :)
2586                         $callbacks = array_merge(
2587                                 $this->mTrxIdleCallbacks,
2588                                 $this->mTrxEndCallbacks // include "transaction resolution" callbacks
2589                         );
2590                         $this->mTrxIdleCallbacks = []; // consumed (and recursion guard)
2591                         $this->mTrxEndCallbacks = []; // consumed (recursion guard)
2592                         foreach ( $callbacks as $callback ) {
2593                                 try {
2594                                         list( $phpCallback ) = $callback;
2595                                         $this->clearFlag( DBO_TRX ); // make each query its own transaction
2596                                         call_user_func_array( $phpCallback, [ $trigger ] );
2597                                         if ( $autoTrx ) {
2598                                                 $this->setFlag( DBO_TRX ); // restore automatic begin()
2599                                         } else {
2600                                                 $this->clearFlag( DBO_TRX ); // restore auto-commit
2601                                         }
2602                                 } catch ( Exception $ex ) {
2603                                         call_user_func( $this->errorLogger, $ex );
2604                                         $e = $e ?: $ex;
2605                                         // Some callbacks may use startAtomic/endAtomic, so make sure
2606                                         // their transactions are ended so other callbacks don't fail
2607                                         if ( $this->trxLevel() ) {
2608                                                 $this->rollback( __METHOD__, self::FLUSHING_INTERNAL );
2609                                         }
2610                                 }
2611                         }
2612                 } while ( count( $this->mTrxIdleCallbacks ) );
2613
2614                 if ( $e instanceof Exception ) {
2615                         throw $e; // re-throw any first exception
2616                 }
2617         }
2618
2619         /**
2620          * Actually run and consume any "on transaction pre-commit" callbacks.
2621          *
2622          * This method should not be used outside of Database/LoadBalancer
2623          *
2624          * @since 1.22
2625          * @throws Exception
2626          */
2627         public function runOnTransactionPreCommitCallbacks() {
2628                 $e = null; // first exception
2629                 do { // callbacks may add callbacks :)
2630                         $callbacks = $this->mTrxPreCommitCallbacks;
2631                         $this->mTrxPreCommitCallbacks = []; // consumed (and recursion guard)
2632                         foreach ( $callbacks as $callback ) {
2633                                 try {
2634                                         list( $phpCallback ) = $callback;
2635                                         call_user_func( $phpCallback );
2636                                 } catch ( Exception $ex ) {
2637                                         call_user_func( $this->errorLogger, $ex );
2638                                         $e = $e ?: $ex;
2639                                 }
2640                         }
2641                 } while ( count( $this->mTrxPreCommitCallbacks ) );
2642
2643                 if ( $e instanceof Exception ) {
2644                         throw $e; // re-throw any first exception
2645                 }
2646         }
2647
2648         /**
2649          * Actually run any "transaction listener" callbacks.
2650          *
2651          * This method should not be used outside of Database/LoadBalancer
2652          *
2653          * @param integer $trigger IDatabase::TRIGGER_* constant
2654          * @throws Exception
2655          * @since 1.20
2656          */
2657         public function runTransactionListenerCallbacks( $trigger ) {
2658                 if ( $this->mTrxEndCallbacksSuppressed ) {
2659                         return;
2660                 }
2661
2662                 /** @var Exception $e */
2663                 $e = null; // first exception
2664
2665                 foreach ( $this->mTrxRecurringCallbacks as $phpCallback ) {
2666                         try {
2667                                 $phpCallback( $trigger, $this );
2668                         } catch ( Exception $ex ) {
2669                                 call_user_func( $this->errorLogger, $ex );
2670                                 $e = $e ?: $ex;
2671                         }
2672                 }
2673
2674                 if ( $e instanceof Exception ) {
2675                         throw $e; // re-throw any first exception
2676                 }
2677         }
2678
2679         final public function startAtomic( $fname = __METHOD__ ) {
2680                 if ( !$this->mTrxLevel ) {
2681                         $this->begin( $fname, self::TRANSACTION_INTERNAL );
2682                         // If DBO_TRX is set, a series of startAtomic/endAtomic pairs will result
2683                         // in all changes being in one transaction to keep requests transactional.
2684                         if ( !$this->getFlag( DBO_TRX ) ) {
2685                                 $this->mTrxAutomaticAtomic = true;
2686                         }
2687                 }
2688
2689                 $this->mTrxAtomicLevels[] = $fname;
2690         }
2691
2692         final public function endAtomic( $fname = __METHOD__ ) {
2693                 if ( !$this->mTrxLevel ) {
2694                         throw new DBUnexpectedError( $this, "No atomic transaction is open (got $fname)." );
2695                 }
2696                 if ( !$this->mTrxAtomicLevels ||
2697                         array_pop( $this->mTrxAtomicLevels ) !== $fname
2698                 ) {
2699                         throw new DBUnexpectedError( $this, "Invalid atomic section ended (got $fname)." );
2700                 }
2701
2702                 if ( !$this->mTrxAtomicLevels && $this->mTrxAutomaticAtomic ) {
2703                         $this->commit( $fname, self::FLUSHING_INTERNAL );
2704                 }
2705         }
2706
2707         final public function doAtomicSection( $fname, callable $callback ) {
2708                 $this->startAtomic( $fname );
2709                 try {
2710                         $res = call_user_func_array( $callback, [ $this, $fname ] );
2711                 } catch ( Exception $e ) {
2712                         $this->rollback( $fname, self::FLUSHING_INTERNAL );
2713                         throw $e;
2714                 }
2715                 $this->endAtomic( $fname );
2716
2717                 return $res;
2718         }
2719
2720         final public function begin( $fname = __METHOD__, $mode = self::TRANSACTION_EXPLICIT ) {
2721                 // Protect against mismatched atomic section, transaction nesting, and snapshot loss
2722                 if ( $this->mTrxLevel ) {
2723                         if ( $this->mTrxAtomicLevels ) {
2724                                 $levels = implode( ', ', $this->mTrxAtomicLevels );
2725                                 $msg = "$fname: Got explicit BEGIN while atomic section(s) $levels are open.";
2726                                 throw new DBUnexpectedError( $this, $msg );
2727                         } elseif ( !$this->mTrxAutomatic ) {
2728                                 $msg = "$fname: Explicit transaction already active (from {$this->mTrxFname}).";
2729                                 throw new DBUnexpectedError( $this, $msg );
2730                         } else {
2731                                 // @TODO: make this an exception at some point
2732                                 $msg = "$fname: Implicit transaction already active (from {$this->mTrxFname}).";
2733                                 $this->queryLogger->error( $msg );
2734                                 return; // join the main transaction set
2735                         }
2736                 } elseif ( $this->getFlag( DBO_TRX ) && $mode !== self::TRANSACTION_INTERNAL ) {
2737                         // @TODO: make this an exception at some point
2738                         $msg = "$fname: Implicit transaction expected (DBO_TRX set).";
2739                         $this->queryLogger->error( $msg );
2740                         return; // let any writes be in the main transaction
2741                 }
2742
2743                 // Avoid fatals if close() was called
2744                 $this->assertOpen();
2745
2746                 $this->doBegin( $fname );
2747                 $this->mTrxTimestamp = microtime( true );
2748                 $this->mTrxFname = $fname;
2749                 $this->mTrxDoneWrites = false;
2750                 $this->mTrxAutomatic = ( $mode === self::TRANSACTION_INTERNAL );
2751                 $this->mTrxAutomaticAtomic = false;
2752                 $this->mTrxAtomicLevels = [];
2753                 $this->mTrxShortId = sprintf( '%06x', mt_rand( 0, 0xffffff ) );
2754                 $this->mTrxWriteDuration = 0.0;
2755                 $this->mTrxWriteQueryCount = 0;
2756                 $this->mTrxWriteAdjDuration = 0.0;
2757                 $this->mTrxWriteAdjQueryCount = 0;
2758                 $this->mTrxWriteCallers = [];
2759                 // First SELECT after BEGIN will establish the snapshot in REPEATABLE-READ.
2760                 // Get an estimate of the replica DB lag before then, treating estimate staleness
2761                 // as lag itself just to be safe
2762                 $status = $this->getApproximateLagStatus();
2763                 $this->mTrxReplicaLag = $status['lag'] + ( microtime( true ) - $status['since'] );
2764         }
2765
2766         /**
2767          * Issues the BEGIN command to the database server.
2768          *
2769          * @see DatabaseBase::begin()
2770          * @param string $fname
2771          */
2772         protected function doBegin( $fname ) {
2773                 $this->query( 'BEGIN', $fname );
2774                 $this->mTrxLevel = 1;
2775         }
2776
2777         final public function commit( $fname = __METHOD__, $flush = '' ) {
2778                 if ( $this->mTrxLevel && $this->mTrxAtomicLevels ) {
2779                         // There are still atomic sections open. This cannot be ignored
2780                         $levels = implode( ', ', $this->mTrxAtomicLevels );
2781                         throw new DBUnexpectedError(
2782                                 $this,
2783                                 "$fname: Got COMMIT while atomic sections $levels are still open."
2784                         );
2785                 }
2786
2787                 if ( $flush === self::FLUSHING_INTERNAL || $flush === self::FLUSHING_ALL_PEERS ) {
2788                         if ( !$this->mTrxLevel ) {
2789                                 return; // nothing to do
2790                         } elseif ( !$this->mTrxAutomatic ) {
2791                                 throw new DBUnexpectedError(
2792                                         $this,
2793                                         "$fname: Flushing an explicit transaction, getting out of sync."
2794                                 );
2795                         }
2796                 } else {
2797                         if ( !$this->mTrxLevel ) {
2798                                 $this->queryLogger->error( "$fname: No transaction to commit, something got out of sync." );
2799                                 return; // nothing to do
2800                         } elseif ( $this->mTrxAutomatic ) {
2801                                 // @TODO: make this an exception at some point
2802                                 $msg = "$fname: Explicit commit of implicit transaction.";
2803                                 $this->queryLogger->error( $msg );
2804                                 return; // wait for the main transaction set commit round
2805                         }
2806                 }
2807
2808                 // Avoid fatals if close() was called
2809                 $this->assertOpen();
2810
2811                 $this->runOnTransactionPreCommitCallbacks();
2812                 $writeTime = $this->pendingWriteQueryDuration( self::ESTIMATE_DB_APPLY );
2813                 $this->doCommit( $fname );
2814                 if ( $this->mTrxDoneWrites ) {
2815                         $this->mDoneWrites = microtime( true );
2816                         $this->trxProfiler->transactionWritingOut(
2817                                 $this->mServer, $this->mDBname, $this->mTrxShortId, $writeTime );
2818                 }
2819
2820                 $this->runOnTransactionIdleCallbacks( self::TRIGGER_COMMIT );
2821                 $this->runTransactionListenerCallbacks( self::TRIGGER_COMMIT );
2822         }
2823
2824         /**
2825          * Issues the COMMIT command to the database server.
2826          *
2827          * @see DatabaseBase::commit()
2828          * @param string $fname
2829          */
2830         protected function doCommit( $fname ) {
2831                 if ( $this->mTrxLevel ) {
2832                         $this->query( 'COMMIT', $fname );
2833                         $this->mTrxLevel = 0;
2834                 }
2835         }
2836
2837         final public function rollback( $fname = __METHOD__, $flush = '' ) {
2838                 if ( $flush === self::FLUSHING_INTERNAL || $flush === self::FLUSHING_ALL_PEERS ) {
2839                         if ( !$this->mTrxLevel ) {
2840                                 return; // nothing to do
2841                         }
2842                 } else {
2843                         if ( !$this->mTrxLevel ) {
2844                                 $this->queryLogger->error(
2845                                         "$fname: No transaction to rollback, something got out of sync." );
2846                                 return; // nothing to do
2847                         } elseif ( $this->getFlag( DBO_TRX ) ) {
2848                                 throw new DBUnexpectedError(
2849                                         $this,
2850                                         "$fname: Expected mass rollback of all peer databases (DBO_TRX set)."
2851                                 );
2852                         }
2853                 }
2854
2855                 // Avoid fatals if close() was called
2856                 $this->assertOpen();
2857
2858                 $this->doRollback( $fname );
2859                 $this->mTrxAtomicLevels = [];
2860                 if ( $this->mTrxDoneWrites ) {
2861                         $this->trxProfiler->transactionWritingOut(
2862                                 $this->mServer, $this->mDBname, $this->mTrxShortId );
2863                 }
2864
2865                 $this->mTrxIdleCallbacks = []; // clear
2866                 $this->mTrxPreCommitCallbacks = []; // clear
2867                 $this->runOnTransactionIdleCallbacks( self::TRIGGER_ROLLBACK );
2868                 $this->runTransactionListenerCallbacks( self::TRIGGER_ROLLBACK );
2869         }
2870
2871         /**
2872          * Issues the ROLLBACK command to the database server.
2873          *
2874          * @see DatabaseBase::rollback()
2875          * @param string $fname
2876          */
2877         protected function doRollback( $fname ) {
2878                 if ( $this->mTrxLevel ) {
2879                         # Disconnects cause rollback anyway, so ignore those errors
2880                         $ignoreErrors = true;
2881                         $this->query( 'ROLLBACK', $fname, $ignoreErrors );
2882                         $this->mTrxLevel = 0;
2883                 }
2884         }
2885
2886         public function flushSnapshot( $fname = __METHOD__ ) {
2887                 if ( $this->writesOrCallbacksPending() || $this->explicitTrxActive() ) {
2888                         // This only flushes transactions to clear snapshots, not to write data
2889                         $fnames = implode( ', ', $this->pendingWriteAndCallbackCallers() );
2890                         throw new DBUnexpectedError(
2891                                 $this,
2892                                 "$fname: Cannot COMMIT to clear snapshot because writes are pending ($fnames)."
2893                         );
2894                 }
2895
2896                 $this->commit( $fname, self::FLUSHING_INTERNAL );
2897         }
2898
2899         public function explicitTrxActive() {
2900                 return $this->mTrxLevel && ( $this->mTrxAtomicLevels || !$this->mTrxAutomatic );
2901         }
2902
2903         /**
2904          * Creates a new table with structure copied from existing table
2905          * Note that unlike most database abstraction functions, this function does not
2906          * automatically append database prefix, because it works at a lower
2907          * abstraction level.
2908          * The table names passed to this function shall not be quoted (this
2909          * function calls addIdentifierQuotes when needed).
2910          *
2911          * @param string $oldName Name of table whose structure should be copied
2912          * @param string $newName Name of table to be created
2913          * @param bool $temporary Whether the new table should be temporary
2914          * @param string $fname Calling function name
2915          * @throws RuntimeException
2916          * @return bool True if operation was successful
2917          */
2918         public function duplicateTableStructure( $oldName, $newName, $temporary = false,
2919                 $fname = __METHOD__
2920         ) {
2921                 throw new RuntimeException( __METHOD__ . ' is not implemented in descendant class' );
2922         }
2923
2924         function listTables( $prefix = null, $fname = __METHOD__ ) {
2925                 throw new RuntimeException( __METHOD__ . ' is not implemented in descendant class' );
2926         }
2927
2928         /**
2929          * Reset the views process cache set by listViews()
2930          * @since 1.22
2931          */
2932         final public function clearViewsCache() {
2933                 $this->allViews = null;
2934         }
2935
2936         /**
2937          * Lists all the VIEWs in the database
2938          *
2939          * For caching purposes the list of all views should be stored in
2940          * $this->allViews. The process cache can be cleared with clearViewsCache()
2941          *
2942          * @param string $prefix Only show VIEWs with this prefix, eg. unit_test_
2943          * @param string $fname Name of calling function
2944          * @throws RuntimeException
2945          * @return array
2946          * @since 1.22
2947          */
2948         public function listViews( $prefix = null, $fname = __METHOD__ ) {
2949                 throw new RuntimeException( __METHOD__ . ' is not implemented in descendant class' );
2950         }
2951
2952         /**
2953          * Differentiates between a TABLE and a VIEW
2954          *
2955          * @param string $name Name of the database-structure to test.
2956          * @throws RuntimeException
2957          * @return bool
2958          * @since 1.22
2959          */
2960         public function isView( $name ) {
2961                 throw new RuntimeException( __METHOD__ . ' is not implemented in descendant class' );
2962         }
2963
2964         public function timestamp( $ts = 0 ) {
2965                 $t = new ConvertableTimestamp( $ts );
2966                 // Let errors bubble up to avoid putting garbage in the DB
2967                 return $t->getTimestamp( TS_MW );
2968         }
2969
2970         public function timestampOrNull( $ts = null ) {
2971                 if ( is_null( $ts ) ) {
2972                         return null;
2973                 } else {
2974                         return $this->timestamp( $ts );
2975                 }
2976         }
2977
2978         /**
2979          * Take the result from a query, and wrap it in a ResultWrapper if
2980          * necessary. Boolean values are passed through as is, to indicate success
2981          * of write queries or failure.
2982          *
2983          * Once upon a time, DatabaseBase::query() returned a bare MySQL result
2984          * resource, and it was necessary to call this function to convert it to
2985          * a wrapper. Nowadays, raw database objects are never exposed to external
2986          * callers, so this is unnecessary in external code.
2987          *
2988          * @param bool|ResultWrapper|resource|object $result
2989          * @return bool|ResultWrapper
2990          */
2991         protected function resultObject( $result ) {
2992                 if ( !$result ) {
2993                         return false;
2994                 } elseif ( $result instanceof ResultWrapper ) {
2995                         return $result;
2996                 } elseif ( $result === true ) {
2997                         // Successful write query
2998                         return $result;
2999                 } else {
3000                         return new ResultWrapper( $this, $result );
3001                 }
3002         }
3003
3004         public function ping( &$rtt = null ) {
3005                 // Avoid hitting the server if it was hit recently
3006                 if ( $this->isOpen() && ( microtime( true ) - $this->lastPing ) < self::PING_TTL ) {
3007                         if ( !func_num_args() || $this->mRTTEstimate > 0 ) {
3008                                 $rtt = $this->mRTTEstimate;
3009                                 return true; // don't care about $rtt
3010                         }
3011                 }
3012
3013                 // This will reconnect if possible or return false if not
3014                 $this->clearFlag( DBO_TRX, self::REMEMBER_PRIOR );
3015                 $ok = ( $this->query( self::PING_QUERY, __METHOD__, true ) !== false );
3016                 $this->restoreFlags( self::RESTORE_PRIOR );
3017
3018                 if ( $ok ) {
3019                         $rtt = $this->mRTTEstimate;
3020                 }
3021
3022                 return $ok;
3023         }
3024
3025         /**
3026          * @return bool
3027          */
3028         protected function reconnect() {
3029                 $this->closeConnection();
3030                 $this->mOpened = false;
3031                 $this->mConn = false;
3032                 try {
3033                         $this->open( $this->mServer, $this->mUser, $this->mPassword, $this->mDBname );
3034                         $this->lastPing = microtime( true );
3035                         $ok = true;
3036                 } catch ( DBConnectionError $e ) {
3037                         $ok = false;
3038                 }
3039
3040                 return $ok;
3041         }
3042
3043         public function getSessionLagStatus() {
3044                 return $this->getTransactionLagStatus() ?: $this->getApproximateLagStatus();
3045         }
3046
3047         /**
3048          * Get the replica DB lag when the current transaction started
3049          *
3050          * This is useful when transactions might use snapshot isolation
3051          * (e.g. REPEATABLE-READ in innodb), so the "real" lag of that data
3052          * is this lag plus transaction duration. If they don't, it is still
3053          * safe to be pessimistic. This returns null if there is no transaction.
3054          *
3055          * @return array|null ('lag': seconds or false on error, 'since': UNIX timestamp of BEGIN)
3056          * @since 1.27
3057          */
3058         public function getTransactionLagStatus() {
3059                 return $this->mTrxLevel
3060                         ? [ 'lag' => $this->mTrxReplicaLag, 'since' => $this->trxTimestamp() ]
3061                         : null;
3062         }
3063
3064         /**
3065          * Get a replica DB lag estimate for this server
3066          *
3067          * @return array ('lag': seconds or false on error, 'since': UNIX timestamp of estimate)
3068          * @since 1.27
3069          */
3070         public function getApproximateLagStatus() {
3071                 return [
3072                         'lag'   => $this->getLBInfo( 'replica' ) ? $this->getLag() : 0,
3073                         'since' => microtime( true )
3074                 ];
3075         }
3076
3077         /**
3078          * Merge the result of getSessionLagStatus() for several DBs
3079          * using the most pessimistic values to estimate the lag of
3080          * any data derived from them in combination
3081          *
3082          * This is information is useful for caching modules
3083          *
3084          * @see WANObjectCache::set()
3085          * @see WANObjectCache::getWithSetCallback()
3086          *
3087          * @param IDatabase $db1
3088          * @param IDatabase ...
3089          * @return array Map of values:
3090          *   - lag: highest lag of any of the DBs or false on error (e.g. replication stopped)
3091          *   - since: oldest UNIX timestamp of any of the DB lag estimates
3092          *   - pending: whether any of the DBs have uncommitted changes
3093          * @since 1.27
3094          */
3095         public static function getCacheSetOptions( IDatabase $db1 ) {
3096                 $res = [ 'lag' => 0, 'since' => INF, 'pending' => false ];
3097                 foreach ( func_get_args() as $db ) {
3098                         /** @var IDatabase $db */
3099                         $status = $db->getSessionLagStatus();
3100                         if ( $status['lag'] === false ) {
3101                                 $res['lag'] = false;
3102                         } elseif ( $res['lag'] !== false ) {
3103                                 $res['lag'] = max( $res['lag'], $status['lag'] );
3104                         }
3105                         $res['since'] = min( $res['since'], $status['since'] );
3106                         $res['pending'] = $res['pending'] ?: $db->writesPending();
3107                 }
3108
3109                 return $res;
3110         }
3111
3112         public function getLag() {
3113                 return 0;
3114         }
3115
3116         function maxListLen() {
3117                 return 0;
3118         }
3119
3120         public function encodeBlob( $b ) {
3121                 return $b;
3122         }
3123
3124         public function decodeBlob( $b ) {
3125                 if ( $b instanceof Blob ) {
3126                         $b = $b->fetch();
3127                 }
3128                 return $b;
3129         }
3130
3131         public function setSessionOptions( array $options ) {
3132         }
3133
3134         /**
3135          * Read and execute SQL commands from a file.
3136          *
3137          * Returns true on success, error string or exception on failure (depending
3138          * on object's error ignore settings).
3139          *
3140          * @param string $filename File name to open
3141          * @param bool|callable $lineCallback Optional function called before reading each line
3142          * @param bool|callable $resultCallback Optional function called for each MySQL result
3143          * @param bool|string $fname Calling function name or false if name should be
3144          *   generated dynamically using $filename
3145          * @param bool|callable $inputCallback Optional function called for each
3146          *   complete line sent
3147          * @return bool|string
3148          * @throws Exception
3149          */
3150         public function sourceFile(
3151                 $filename, $lineCallback = false, $resultCallback = false, $fname = false, $inputCallback = false
3152         ) {
3153                 MediaWiki\suppressWarnings();
3154                 $fp = fopen( $filename, 'r' );
3155                 MediaWiki\restoreWarnings();
3156
3157                 if ( false === $fp ) {
3158                         throw new RuntimeException( "Could not open \"{$filename}\".\n" );
3159                 }
3160
3161                 if ( !$fname ) {
3162                         $fname = __METHOD__ . "( $filename )";
3163                 }
3164
3165                 try {
3166                         $error = $this->sourceStream( $fp, $lineCallback, $resultCallback, $fname, $inputCallback );
3167                 } catch ( Exception $e ) {
3168                         fclose( $fp );
3169                         throw $e;
3170                 }
3171
3172                 fclose( $fp );
3173
3174                 return $error;
3175         }
3176
3177         public function setSchemaVars( $vars ) {
3178                 $this->mSchemaVars = $vars;
3179         }
3180
3181         /**
3182          * Read and execute commands from an open file handle.
3183          *
3184          * Returns true on success, error string or exception on failure (depending
3185          * on object's error ignore settings).
3186          *
3187          * @param resource $fp File handle
3188          * @param bool|callable $lineCallback Optional function called before reading each query
3189          * @param bool|callable $resultCallback Optional function called for each MySQL result
3190          * @param string $fname Calling function name
3191          * @param bool|callable $inputCallback Optional function called for each complete query sent
3192          * @return bool|string
3193          */
3194         public function sourceStream( $fp, $lineCallback = false, $resultCallback = false,
3195                 $fname = __METHOD__, $inputCallback = false
3196         ) {
3197                 $cmd = '';
3198
3199                 while ( !feof( $fp ) ) {
3200                         if ( $lineCallback ) {
3201                                 call_user_func( $lineCallback );
3202                         }
3203
3204                         $line = trim( fgets( $fp ) );
3205
3206                         if ( $line == '' ) {
3207                                 continue;
3208                         }
3209
3210                         if ( '-' == $line[0] && '-' == $line[1] ) {
3211                                 continue;
3212                         }
3213
3214                         if ( $cmd != '' ) {
3215                                 $cmd .= ' ';
3216                         }
3217
3218                         $done = $this->streamStatementEnd( $cmd, $line );
3219
3220                         $cmd .= "$line\n";
3221
3222                         if ( $done || feof( $fp ) ) {
3223                                 $cmd = $this->replaceVars( $cmd );
3224
3225                                 if ( ( $inputCallback && call_user_func( $inputCallback, $cmd ) ) || !$inputCallback ) {
3226                                         $res = $this->query( $cmd, $fname );
3227
3228                                         if ( $resultCallback ) {
3229                                                 call_user_func( $resultCallback, $res, $this );
3230                                         }
3231
3232                                         if ( false === $res ) {
3233                                                 $err = $this->lastError();
3234
3235                                                 return "Query \"{$cmd}\" failed with error code \"$err\".\n";
3236                                         }
3237                                 }
3238                                 $cmd = '';
3239                         }
3240                 }
3241
3242                 return true;
3243         }
3244
3245         /**
3246          * Called by sourceStream() to check if we've reached a statement end
3247          *
3248          * @param string $sql SQL assembled so far
3249          * @param string $newLine New line about to be added to $sql
3250          * @return bool Whether $newLine contains end of the statement
3251          */
3252         public function streamStatementEnd( &$sql, &$newLine ) {
3253                 if ( $this->delimiter ) {
3254                         $prev = $newLine;
3255                         $newLine = preg_replace( '/' . preg_quote( $this->delimiter, '/' ) . '$/', '', $newLine );
3256                         if ( $newLine != $prev ) {
3257                                 return true;
3258                         }
3259                 }
3260
3261                 return false;
3262         }
3263
3264         /**
3265          * Database independent variable replacement. Replaces a set of variables
3266          * in an SQL statement with their contents as given by $this->getSchemaVars().
3267          *
3268          * Supports '{$var}' `{$var}` and / *$var* / (without the spaces) style variables.
3269          *
3270          * - '{$var}' should be used for text and is passed through the database's
3271          *   addQuotes method.
3272          * - `{$var}` should be used for identifiers (e.g. table and database names).
3273          *   It is passed through the database's addIdentifierQuotes method which
3274          *   can be overridden if the database uses something other than backticks.
3275          * - / *_* / or / *$wgDBprefix* / passes the name that follows through the
3276          *   database's tableName method.
3277          * - / *i* / passes the name that follows through the database's indexName method.
3278          * - In all other cases, / *$var* / is left unencoded. Except for table options,
3279          *   its use should be avoided. In 1.24 and older, string encoding was applied.
3280          *
3281          * @param string $ins SQL statement to replace variables in
3282          * @return string The new SQL statement with variables replaced
3283          */
3284         protected function replaceVars( $ins ) {
3285                 $vars = $this->getSchemaVars();
3286                 return preg_replace_callback(
3287                         '!
3288                                 /\* (\$wgDBprefix|[_i]) \*/ (\w*) | # 1-2. tableName, indexName
3289                                 \'\{\$ (\w+) }\'                  | # 3. addQuotes
3290                                 `\{\$ (\w+) }`                    | # 4. addIdentifierQuotes
3291                                 /\*\$ (\w+) \*/                     # 5. leave unencoded
3292                         !x',
3293                         function ( $m ) use ( $vars ) {
3294                                 // Note: Because of <https://bugs.php.net/bug.php?id=51881>,
3295                                 // check for both nonexistent keys *and* the empty string.
3296                                 if ( isset( $m[1] ) && $m[1] !== '' ) {
3297                                         if ( $m[1] === 'i' ) {
3298                                                 return $this->indexName( $m[2] );
3299                                         } else {
3300                                                 return $this->tableName( $m[2] );
3301                                         }
3302                                 } elseif ( isset( $m[3] ) && $m[3] !== '' && array_key_exists( $m[3], $vars ) ) {
3303                                         return $this->addQuotes( $vars[$m[3]] );
3304                                 } elseif ( isset( $m[4] ) && $m[4] !== '' && array_key_exists( $m[4], $vars ) ) {
3305                                         return $this->addIdentifierQuotes( $vars[$m[4]] );
3306                                 } elseif ( isset( $m[5] ) && $m[5] !== '' && array_key_exists( $m[5], $vars ) ) {
3307                                         return $vars[$m[5]];
3308                                 } else {
3309                                         return $m[0];
3310                                 }
3311                         },
3312                         $ins
3313                 );
3314         }
3315
3316         /**
3317          * Get schema variables. If none have been set via setSchemaVars(), then
3318          * use some defaults from the current object.
3319          *
3320          * @return array
3321          */
3322         protected function getSchemaVars() {
3323                 if ( $this->mSchemaVars ) {
3324                         return $this->mSchemaVars;
3325                 } else {
3326                         return $this->getDefaultSchemaVars();
3327                 }
3328         }
3329
3330         /**
3331          * Get schema variables to use if none have been set via setSchemaVars().
3332          *
3333          * Override this in derived classes to provide variables for tables.sql
3334          * and SQL patch files.
3335          *
3336          * @return array
3337          */
3338         protected function getDefaultSchemaVars() {
3339                 return [];
3340         }
3341
3342         public function lockIsFree( $lockName, $method ) {
3343                 return true;
3344         }
3345
3346         public function lock( $lockName, $method, $timeout = 5 ) {
3347                 $this->mNamedLocksHeld[$lockName] = 1;
3348
3349                 return true;
3350         }
3351
3352         public function unlock( $lockName, $method ) {
3353                 unset( $this->mNamedLocksHeld[$lockName] );
3354
3355                 return true;
3356         }
3357
3358         public function getScopedLockAndFlush( $lockKey, $fname, $timeout ) {
3359                 if ( $this->writesOrCallbacksPending() ) {
3360                         // This only flushes transactions to clear snapshots, not to write data
3361                         $fnames = implode( ', ', $this->pendingWriteAndCallbackCallers() );
3362                         throw new DBUnexpectedError(
3363                                 $this,
3364                                 "$fname: Cannot COMMIT to clear snapshot because writes are pending ($fnames)."
3365                         );
3366                 }
3367
3368                 if ( !$this->lock( $lockKey, $fname, $timeout ) ) {
3369                         return null;
3370                 }
3371
3372                 $unlocker = new ScopedCallback( function () use ( $lockKey, $fname ) {
3373                         if ( $this->trxLevel() ) {
3374                                 // There is a good chance an exception was thrown, causing any early return
3375                                 // from the caller. Let any error handler get a chance to issue rollback().
3376                                 // If there isn't one, let the error bubble up and trigger server-side rollback.
3377                                 $this->onTransactionResolution(
3378                                         function () use ( $lockKey, $fname ) {
3379                                                 $this->unlock( $lockKey, $fname );
3380                                         },
3381                                         $fname
3382                                 );
3383                         } else {
3384                                 $this->unlock( $lockKey, $fname );
3385                         }
3386                 } );
3387
3388                 $this->commit( $fname, self::FLUSHING_INTERNAL );
3389
3390                 return $unlocker;
3391         }
3392
3393         public function namedLocksEnqueue() {
3394                 return false;
3395         }
3396
3397         /**
3398          * Lock specific tables
3399          *
3400          * @param array $read Array of tables to lock for read access
3401          * @param array $write Array of tables to lock for write access
3402          * @param string $method Name of caller
3403          * @param bool $lowPriority Whether to indicate writes to be LOW PRIORITY
3404          * @return bool
3405          */
3406         public function lockTables( $read, $write, $method, $lowPriority = true ) {
3407                 return true;
3408         }
3409
3410         /**
3411          * Unlock specific tables
3412          *
3413          * @param string $method The caller
3414          * @return bool
3415          */
3416         public function unlockTables( $method ) {
3417                 return true;
3418         }
3419
3420         /**
3421          * Delete a table
3422          * @param string $tableName
3423          * @param string $fName
3424          * @return bool|ResultWrapper
3425          * @since 1.18
3426          */
3427         public function dropTable( $tableName, $fName = __METHOD__ ) {
3428                 if ( !$this->tableExists( $tableName, $fName ) ) {
3429                         return false;
3430                 }
3431                 $sql = "DROP TABLE " . $this->tableName( $tableName ) . " CASCADE";
3432
3433                 return $this->query( $sql, $fName );
3434         }
3435
3436         public function getInfinity() {
3437                 return 'infinity';
3438         }
3439
3440         public function encodeExpiry( $expiry ) {
3441                 return ( $expiry == '' || $expiry == 'infinity' || $expiry == $this->getInfinity() )
3442                         ? $this->getInfinity()
3443                         : $this->timestamp( $expiry );
3444         }
3445
3446         public function decodeExpiry( $expiry, $format = TS_MW ) {
3447                 if ( $expiry == '' || $expiry == 'infinity' || $expiry == $this->getInfinity() ) {
3448                         return 'infinity';
3449                 }
3450
3451                 try {
3452                         $t = new ConvertableTimestamp( $expiry );
3453
3454                         return $t->getTimestamp( $format );
3455                 } catch ( TimestampException $e ) {
3456                         return false;
3457                 }
3458         }
3459
3460         public function setBigSelects( $value = true ) {
3461                 // no-op
3462         }
3463
3464         public function isReadOnly() {
3465                 return ( $this->getReadOnlyReason() !== false );
3466         }
3467
3468         /**
3469          * @return string|bool Reason this DB is read-only or false if it is not
3470          */
3471         protected function getReadOnlyReason() {
3472                 $reason = $this->getLBInfo( 'readOnlyReason' );
3473
3474                 return is_string( $reason ) ? $reason : false;
3475         }
3476
3477         public function setTableAliases( array $aliases ) {
3478                 $this->tableAliases = $aliases;
3479         }
3480
3481         /**
3482          * @return bool Whether a DB user is required to access the DB
3483          * @since 1.28
3484          */
3485         protected function requiresDatabaseUser() {
3486                 return true;
3487         }
3488
3489         /**
3490          * @since 1.19
3491          * @return string
3492          */
3493         public function __toString() {
3494                 return (string)$this->mConn;
3495         }
3496
3497         /**
3498          * Called by serialize. Throw an exception when DB connection is serialized.
3499          * This causes problems on some database engines because the connection is
3500          * not restored on unserialize.
3501          */
3502         public function __sleep() {
3503                 throw new RuntimeException( 'Database serialization may cause problems, since ' .
3504                         'the connection is not restored on wakeup.' );
3505         }
3506
3507         /**
3508          * Run a few simple sanity checks
3509          */
3510         public function __destruct() {
3511                 if ( $this->mTrxLevel && $this->mTrxDoneWrites ) {
3512                         trigger_error( "Uncommitted DB writes (transaction from {$this->mTrxFname})." );
3513                 }
3514
3515                 $danglingWriters = $this->pendingWriteAndCallbackCallers();
3516                 if ( $danglingWriters ) {
3517                         $fnames = implode( ', ', $danglingWriters );
3518                         trigger_error( "DB transaction writes or callbacks still pending ($fnames)." );
3519                 }
3520         }
3521 }