includes/libs/rdbms/database/Database.php

   1 <?php
   2 /**
   3  * @defgroup Database Database
   4  *
   5  * This file deals with database interface functions
   6  * and query specifics/optimisations.
   7  *
   8  * This program is free software; you can redistribute it and/or modify
   9  * it under the terms of the GNU General Public License as published by
  10  * the Free Software Foundation; either version 2 of the License, or
  11  * (at your option) any later version.
  12  *
  13  * This program is distributed in the hope that it will be useful,
  14  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  15  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
  16  * GNU General Public License for more details.
  17  *
  18  * You should have received a copy of the GNU General Public License along
  19  * with this program; if not, write to the Free Software Foundation, Inc.,
  20  * 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
  21  * http://www.gnu.org/copyleft/gpl.html
  22  *
  23  * @file
  24  * @ingroup Database
  25  */
  26 namespace Wikimedia\Rdbms;
  27
  28 use Psr\Log\LoggerAwareInterface;
  29 use Psr\Log\LoggerInterface;
  30 use Psr\Log\NullLogger;
  31 use Wikimedia\ScopedCallback;
  32 use Wikimedia\Timestamp\ConvertibleTimestamp;
  33 use Wikimedia;
  34 use BagOStuff;
  35 use HashBagOStuff;
  36 use LogicException;
  37 use InvalidArgumentException;
  38 use UnexpectedValueException;
  39 use Exception;
  40 use RuntimeException;
  41
  42 /**
  43  * Relational database abstraction object
  44  *
  45  * @ingroup Database
  46  * @since 1.28
  47  */
  48 abstract class Database implements IDatabase, IMaintainableDatabase, LoggerAwareInterface {
  49         /** Number of times to re-try an operation in case of deadlock */
  50         const DEADLOCK_TRIES = 4;
  51         /** Minimum time to wait before retry, in microseconds */
  52         const DEADLOCK_DELAY_MIN = 500000;
  53         /** Maximum time to wait before retry */
  54         const DEADLOCK_DELAY_MAX = 1500000;
  55
  56         /** How long before it is worth doing a dummy query to test the connection */
  57         const PING_TTL = 1.0;
  58         const PING_QUERY = 'SELECT 1 AS ping';
  59
  60         const TINY_WRITE_SEC = 0.010;
  61         const SLOW_WRITE_SEC = 0.500;
  62         const SMALL_WRITE_ROWS = 100;
  63
  64         /** @var string Whether lock granularity is on the level of the entire database */
  65         const ATTR_DB_LEVEL_LOCKING = 'db-level-locking';
  66
  67         /** @var int New Database instance will not be connected yet when returned */
  68         const NEW_UNCONNECTED = 0;
  69         /** @var int New Database instance will already be connected when returned */
  70         const NEW_CONNECTED = 1;
  71
  72         /** @var string SQL query */
  73         protected $lastQuery = '';
  74         /** @var float|bool UNIX timestamp of last write query */
  75         protected $lastWriteTime = false;
  76         /** @var string|bool */
  77         protected $phpError = false;
  78         /** @var string Server that this instance is currently connected to */
  79         protected $server;
  80         /** @var string User that this instance is currently connected under the name of */
  81         protected $user;
  82         /** @var string Password used to establish the current connection */
  83         protected $password;
  84         /** @var string Database that this instance is currently connected to */
  85         protected $dbName;
  86         /** @var array[] Map of (table => (dbname, schema, prefix) map) */
  87         protected $tableAliases = [];
  88         /** @var string[] Map of (index alias => index) */
  89         protected $indexAliases = [];
  90         /** @var bool Whether this PHP instance is for a CLI script */
  91         protected $cliMode;
  92         /** @var string Agent name for query profiling */
  93         protected $agent;
  94         /** @var array Parameters used by initConnection() to establish a connection */
  95         protected $connectionParams = [];
  96         /** @var BagOStuff APC cache */
  97         protected $srvCache;
  98         /** @var LoggerInterface */
  99         protected $connLogger;
 100         /** @var LoggerInterface */
 101         protected $queryLogger;
 102         /** @var callback Error logging callback */
 103         protected $errorLogger;
 104
 105         /** @var resource|null Database connection */
 106         protected $conn = null;
 107         /** @var bool */
 108         protected $opened = false;
 109
 110         /** @var array[] List of (callable, method name) */
 111         protected $trxIdleCallbacks = [];
 112         /** @var array[] List of (callable, method name) */
 113         protected $trxPreCommitCallbacks = [];
 114         /** @var array[] List of (callable, method name) */
 115         protected $trxEndCallbacks = [];
 116         /** @var callable[] Map of (name => callable) */
 117         protected $trxRecurringCallbacks = [];
 118         /** @var bool Whether to suppress triggering of transaction end callbacks */
 119         protected $trxEndCallbacksSuppressed = false;
 120
 121         /** @var string */
 122         protected $tablePrefix = '';
 123         /** @var string */
 124         protected $schema = '';
 125         /** @var int */
 126         protected $flags;
 127         /** @var array */
 128         protected $lbInfo = [];
 129         /** @var array|bool */
 130         protected $schemaVars = false;
 131         /** @var array */
 132         protected $sessionVars = [];
 133         /** @var array|null */
 134         protected $preparedArgs;
 135         /** @var string|bool|null Stashed value of html_errors INI setting */
 136         protected $htmlErrors;
 137         /** @var string */
 138         protected $delimiter = ';';
 139         /** @var DatabaseDomain */
 140         protected $currentDomain;
 141         /** @var integer|null Rows affected by the last query to query() or its CRUD wrappers */
 142         protected $affectedRowCount;
 143
 144         /**
 145          * Either 1 if a transaction is active or 0 otherwise.
 146          * The other Trx fields may not be meaningfull if this is 0.
 147          *
 148          * @var int
 149          */
 150         protected $trxLevel = 0;
 151         /**
 152          * Either a short hexidecimal string if a transaction is active or ""
 153          *
 154          * @var string
 155          * @see Database::trxLevel
 156          */
 157         protected $trxShortId = '';
 158         /**
 159          * The UNIX time that the transaction started. Callers can assume that if
 160          * snapshot isolation is used, then the data is *at least* up to date to that
 161          * point (possibly more up-to-date since the first SELECT defines the snapshot).
 162          *
 163          * @var float|null
 164          * @see Database::trxLevel
 165          */
 166         private $trxTimestamp = null;
 167         /** @var float Lag estimate at the time of BEGIN */
 168         private $trxReplicaLag = null;
 169         /**
 170          * Remembers the function name given for starting the most recent transaction via begin().
 171          * Used to provide additional context for error reporting.
 172          *
 173          * @var string
 174          * @see Database::trxLevel
 175          */
 176         private $trxFname = null;
 177         /**
 178          * Record if possible write queries were done in the last transaction started
 179          *
 180          * @var bool
 181          * @see Database::trxLevel
 182          */
 183         private $trxDoneWrites = false;
 184         /**
 185          * Record if the current transaction was started implicitly due to DBO_TRX being set.
 186          *
 187          * @var bool
 188          * @see Database::trxLevel
 189          */
 190         private $trxAutomatic = false;
 191         /**
 192          * Counter for atomic savepoint identifiers. Reset when a new transaction begins.
 193          *
 194          * @var int
 195          */
 196         private $trxAtomicCounter = 0;
 197         /**
 198          * Array of levels of atomicity within transactions
 199          *
 200          * @var array
 201          */
 202         private $trxAtomicLevels = [];
 203         /**
 204          * Record if the current transaction was started implicitly by Database::startAtomic
 205          *
 206          * @var bool
 207          */
 208         private $trxAutomaticAtomic = false;
 209         /**
 210          * Track the write query callers of the current transaction
 211          *
 212          * @var string[]
 213          */
 214         private $trxWriteCallers = [];
 215         /**
 216          * @var float Seconds spent in write queries for the current transaction
 217          */
 218         private $trxWriteDuration = 0.0;
 219         /**
 220          * @var int Number of write queries for the current transaction
 221          */
 222         private $trxWriteQueryCount = 0;
 223         /**
 224          * @var int Number of rows affected by write queries for the current transaction
 225          */
 226         private $trxWriteAffectedRows = 0;
 227         /**
 228          * @var float Like trxWriteQueryCount but excludes lock-bound, easy to replicate, queries
 229          */
 230         private $trxWriteAdjDuration = 0.0;
 231         /**
 232          * @var int Number of write queries counted in trxWriteAdjDuration
 233          */
 234         private $trxWriteAdjQueryCount = 0;
 235         /**
 236          * @var float RTT time estimate
 237          */
 238         private $rttEstimate = 0.0;
 239
 240         /** @var array Map of (name => 1) for locks obtained via lock() */
 241         private $namedLocksHeld = [];
 242         /** @var array Map of (table name => 1) for TEMPORARY tables */
 243         protected $sessionTempTables = [];
 244
 245         /** @var IDatabase|null Lazy handle to the master DB this server replicates from */
 246         private $lazyMasterHandle;
 247
 248         /** @var float UNIX timestamp */
 249         protected $lastPing = 0.0;
 250
 251         /** @var int[] Prior flags member variable values */
 252         private $priorFlags = [];
 253
 254         /** @var object|string Class name or object With profileIn/profileOut methods */
 255         protected $profiler;
 256         /** @var TransactionProfiler */
 257         protected $trxProfiler;
 258
 259         /** @var int */
 260         protected $nonNativeInsertSelectBatchSize = 10000;
 261
 262         /**
 263          * @note: exceptions for missing libraries/drivers should be thrown in initConnection()
 264          * @param array $params Parameters passed from Database::factory()
 265          */
 266         protected function __construct( array $params ) {
 267                 foreach ( [ 'host', 'user', 'password', 'dbname' ] as $name ) {
 268                         $this->connectionParams[$name] = $params[$name];
 269                 }
 270
 271                 $this->schema = $params['schema'];
 272                 $this->tablePrefix = $params['tablePrefix'];
 273
 274                 $this->cliMode = $params['cliMode'];
 275                 // Agent name is added to SQL queries in a comment, so make sure it can't break out
 276                 $this->agent = str_replace( '/', '-', $params['agent'] );
 277
 278                 $this->flags = $params['flags'];
 279                 if ( $this->flags & self::DBO_DEFAULT ) {
 280                         if ( $this->cliMode ) {
 281                                 $this->flags &= ~self::DBO_TRX;
 282                         } else {
 283                                 $this->flags |= self::DBO_TRX;
 284                         }
 285                 }
 286                 // Disregard deprecated DBO_IGNORE flag (T189999)
 287                 $this->flags &= ~self::DBO_IGNORE;
 288
 289                 $this->sessionVars = $params['variables'];
 290
 291                 $this->srvCache = isset( $params['srvCache'] )
 292                         ? $params['srvCache']
 293                         : new HashBagOStuff();
 294
 295                 $this->profiler = $params['profiler'];
 296                 $this->trxProfiler = $params['trxProfiler'];
 297                 $this->connLogger = $params['connLogger'];
 298                 $this->queryLogger = $params['queryLogger'];
 299                 $this->errorLogger = $params['errorLogger'];
 300
 301                 if ( isset( $params['nonNativeInsertSelectBatchSize'] ) ) {
 302                         $this->nonNativeInsertSelectBatchSize = $params['nonNativeInsertSelectBatchSize'];
 303                 }
 304
 305                 // Set initial dummy domain until open() sets the final DB/prefix
 306                 $this->currentDomain = DatabaseDomain::newUnspecified();
 307         }
 308
 309         /**
 310          * Initialize the connection to the database over the wire (or to local files)
 311          *
 312          * @throws LogicException
 313          * @throws InvalidArgumentException
 314          * @throws DBConnectionError
 315          * @since 1.31
 316          */
 317         final public function initConnection() {
 318                 if ( $this->isOpen() ) {
 319                         throw new LogicException( __METHOD__ . ': already connected.' );
 320                 }
 321                 // Establish the connection
 322                 $this->doInitConnection();
 323                 // Set the domain object after open() sets the relevant fields
 324                 if ( $this->dbName != '' ) {
 325                         // Domains with server scope but a table prefix are not used by IDatabase classes
 326                         $this->currentDomain = new DatabaseDomain( $this->dbName, null, $this->tablePrefix );
 327                 }
 328         }
 329
 330         /**
 331          * Actually connect to the database over the wire (or to local files)
 332          *
 333          * @throws InvalidArgumentException
 334          * @throws DBConnectionError
 335          * @since 1.31
 336          */
 337         protected function doInitConnection() {
 338                 if ( strlen( $this->connectionParams['user'] ) ) {
 339                         $this->open(
 340                                 $this->connectionParams['host'],
 341                                 $this->connectionParams['user'],
 342                                 $this->connectionParams['password'],
 343                                 $this->connectionParams['dbname']
 344                         );
 345                 } else {
 346                         throw new InvalidArgumentException( "No database user provided." );
 347                 }
 348         }
 349
 350         /**
 351          * Construct a Database subclass instance given a database type and parameters
 352          *
 353          * This also connects to the database immediately upon object construction
 354          *
 355          * @param string $dbType A possible DB type (sqlite, mysql, postgres,...)
 356          * @param array $p Parameter map with keys:
 357          *   - host : The hostname of the DB server
 358          *   - user : The name of the database user the client operates under
 359          *   - password : The password for the database user
 360          *   - dbname : The name of the database to use where queries do not specify one.
 361          *      The database must exist or an error might be thrown. Setting this to the empty string
 362          *      will avoid any such errors and make the handle have no implicit database scope. This is
 363          *      useful for queries like SHOW STATUS, CREATE DATABASE, or DROP DATABASE. Note that a
 364          *      "database" in Postgres is rougly equivalent to an entire MySQL server. This the domain
 365          *      in which user names and such are defined, e.g. users are database-specific in Postgres.
 366          *   - schema : The database schema to use (if supported). A "schema" in Postgres is roughly
 367          *      equivalent to a "database" in MySQL. Note that MySQL and SQLite do not use schemas.
 368          *   - tablePrefix : Optional table prefix that is implicitly added on to all table names
 369          *      recognized in queries. This can be used in place of schemas for handle site farms.
 370          *   - flags : Optional bitfield of DBO_* constants that define connection, protocol,
 371          *      buffering, and transaction behavior. It is STRONGLY adviced to leave the DBO_DEFAULT
 372          *      flag in place UNLESS this this database simply acts as a key/value store.
 373          *   - driver: Optional name of a specific DB client driver. For MySQL, there is only the
 374          *      'mysqli' driver; the old one 'mysql' has been removed.
 375          *   - variables: Optional map of session variables to set after connecting. This can be
 376          *      used to adjust lock timeouts or encoding modes and the like.
 377          *   - connLogger: Optional PSR-3 logger interface instance.
 378          *   - queryLogger: Optional PSR-3 logger interface instance.
 379          *   - profiler: Optional class name or object with profileIn()/profileOut() methods.
 380          *      These will be called in query(), using a simplified version of the SQL that also
 381          *      includes the agent as a SQL comment.
 382          *   - trxProfiler: Optional TransactionProfiler instance.
 383          *   - errorLogger: Optional callback that takes an Exception and logs it.
 384          *   - cliMode: Whether to consider the execution context that of a CLI script.
 385          *   - agent: Optional name used to identify the end-user in query profiling/logging.
 386          *   - srvCache: Optional BagOStuff instance to an APC-style cache.
 387          *   - nonNativeInsertSelectBatchSize: Optional batch size for non-native INSERT SELECT emulation.
 388          * @param int $connect One of the class constants (NEW_CONNECTED, NEW_UNCONNECTED) [optional]
 389          * @return Database|null If the database driver or extension cannot be found
 390          * @throws InvalidArgumentException If the database driver or extension cannot be found
 391          * @since 1.18
 392          */
 393         final public static function factory( $dbType, $p = [], $connect = self::NEW_CONNECTED ) {
 394                 $class = self::getClass( $dbType, isset( $p['driver'] ) ? $p['driver'] : null );
 395
 396                 if ( class_exists( $class ) && is_subclass_of( $class, IDatabase::class ) ) {
 397                         // Resolve some defaults for b/c
 398                         $p['host'] = isset( $p['host'] ) ? $p['host'] : false;
 399                         $p['user'] = isset( $p['user'] ) ? $p['user'] : false;
 400                         $p['password'] = isset( $p['password'] ) ? $p['password'] : false;
 401                         $p['dbname'] = isset( $p['dbname'] ) ? $p['dbname'] : false;
 402                         $p['flags'] = isset( $p['flags'] ) ? $p['flags'] : 0;
 403                         $p['variables'] = isset( $p['variables'] ) ? $p['variables'] : [];
 404                         $p['tablePrefix'] = isset( $p['tablePrefix'] ) ? $p['tablePrefix'] : '';
 405                         $p['schema'] = isset( $p['schema'] ) ? $p['schema'] : '';
 406                         $p['cliMode'] = isset( $p['cliMode'] )
 407                                 ? $p['cliMode']
 408                                 : ( PHP_SAPI === 'cli' || PHP_SAPI === 'phpdbg' );
 409                         $p['agent'] = isset( $p['agent'] ) ? $p['agent'] : '';
 410                         if ( !isset( $p['connLogger'] ) ) {
 411                                 $p['connLogger'] = new NullLogger();
 412                         }
 413                         if ( !isset( $p['queryLogger'] ) ) {
 414                                 $p['queryLogger'] = new NullLogger();
 415                         }
 416                         $p['profiler'] = isset( $p['profiler'] ) ? $p['profiler'] : null;
 417                         if ( !isset( $p['trxProfiler'] ) ) {
 418                                 $p['trxProfiler'] = new TransactionProfiler();
 419                         }
 420                         if ( !isset( $p['errorLogger'] ) ) {
 421                                 $p['errorLogger'] = function ( Exception $e ) {
 422                                         trigger_error( get_class( $e ) . ': ' . $e->getMessage(), E_USER_WARNING );
 423                                 };
 424                         }
 425
 426                         /** @var Database $conn */
 427                         $conn = new $class( $p );
 428                         if ( $connect == self::NEW_CONNECTED ) {
 429                                 $conn->initConnection();
 430                         }
 431                 } else {
 432                         $conn = null;
 433                 }
 434
 435                 return $conn;
 436         }
 437
 438         /**
 439          * @param string $dbType A possible DB type (sqlite, mysql, postgres,...)
 440          * @param string|null $driver Optional name of a specific DB client driver
 441          * @return array Map of (Database::ATTRIBUTE_* constant => value) for all such constants
 442          * @throws InvalidArgumentException
 443          * @since 1.31
 444          */
 445         final public static function attributesFromType( $dbType, $driver = null ) {
 446                 static $defaults = [ self::ATTR_DB_LEVEL_LOCKING => false ];
 447
 448                 $class = self::getClass( $dbType, $driver );
 449
 450                 return call_user_func( [ $class, 'getAttributes' ] ) + $defaults;
 451         }
 452
 453         /**
 454          * @param string $dbType A possible DB type (sqlite, mysql, postgres,...)
 455          * @param string|null $driver Optional name of a specific DB client driver
 456          * @return string Database subclass name to use
 457          * @throws InvalidArgumentException
 458          */
 459         private static function getClass( $dbType, $driver = null ) {
 460                 // For database types with built-in support, the below maps type to IDatabase
 461                 // implementations. For types with multipe driver implementations (PHP extensions),
 462                 // an array can be used, keyed by extension name. In case of an array, the
 463                 // optional 'driver' parameter can be used to force a specific driver. Otherwise,
 464                 // we auto-detect the first available driver. For types without built-in support,
 465                 // an class named "Database<Type>" us used, eg. DatabaseFoo for type 'foo'.
 466                 static $builtinTypes = [
 467                         'mssql' => DatabaseMssql::class,
 468                         'mysql' => [ 'mysqli' => DatabaseMysqli::class ],
 469                         'sqlite' => DatabaseSqlite::class,
 470                         'postgres' => DatabasePostgres::class,
 471                 ];
 472
 473                 $dbType = strtolower( $dbType );
 474                 $class = false;
 475
 476                 if ( isset( $builtinTypes[$dbType] ) ) {
 477                         $possibleDrivers = $builtinTypes[$dbType];
 478                         if ( is_string( $possibleDrivers ) ) {
 479                                 $class = $possibleDrivers;
 480                         } else {
 481                                 if ( (string)$driver !== '' ) {
 482                                         if ( !isset( $possibleDrivers[$driver] ) ) {
 483                                                 throw new InvalidArgumentException( __METHOD__ .
 484                                                         " type '$dbType' does not support driver '{$driver}'" );
 485                                         } else {
 486                                                 $class = $possibleDrivers[$driver];
 487                                         }
 488                                 } else {
 489                                         foreach ( $possibleDrivers as $posDriver => $possibleClass ) {
 490                                                 if ( extension_loaded( $posDriver ) ) {
 491                                                         $class = $possibleClass;
 492                                                         break;
 493                                                 }
 494                                         }
 495                                 }
 496                         }
 497                 } else {
 498                         $class = 'Database' . ucfirst( $dbType );
 499                 }
 500
 501                 if ( $class === false ) {
 502                         throw new InvalidArgumentException( __METHOD__ .
 503                                 " no viable database extension found for type '$dbType'" );
 504                 }
 505
 506                 return $class;
 507         }
 508
 509         /**
 510          * @return array Map of (Database::ATTRIBUTE_* constant => value
 511          * @since 1.31
 512          */
 513         protected static function getAttributes() {
 514                 return [];
 515         }
 516
 517         /**
 518          * Set the PSR-3 logger interface to use for query logging. (The logger
 519          * interfaces for connection logging and error logging can be set with the
 520          * constructor.)
 521          *
 522          * @param LoggerInterface $logger
 523          */
 524         public function setLogger( LoggerInterface $logger ) {
 525                 $this->queryLogger = $logger;
 526         }
 527
 528         public function getServerInfo() {
 529                 return $this->getServerVersion();
 530         }
 531
 532         public function bufferResults( $buffer = null ) {
 533                 $res = !$this->getFlag( self::DBO_NOBUFFER );
 534                 if ( $buffer !== null ) {
 535                         $buffer
 536                                 ? $this->clearFlag( self::DBO_NOBUFFER )
 537                                 : $this->setFlag( self::DBO_NOBUFFER );
 538                 }
 539
 540                 return $res;
 541         }
 542
 543         public function trxLevel() {
 544                 return $this->trxLevel;
 545         }
 546
 547         public function trxTimestamp() {
 548                 return $this->trxLevel ? $this->trxTimestamp : null;
 549         }
 550
 551         public function tablePrefix( $prefix = null ) {
 552                 $old = $this->tablePrefix;
 553                 if ( $prefix !== null ) {
 554                         $this->tablePrefix = $prefix;
 555                         $this->currentDomain = ( $this->dbName != '' )
 556                                 ? new DatabaseDomain( $this->dbName, null, $this->tablePrefix )
 557                                 : DatabaseDomain::newUnspecified();
 558                 }
 559
 560                 return $old;
 561         }
 562
 563         public function dbSchema( $schema = null ) {
 564                 $old = $this->schema;
 565                 if ( $schema !== null ) {
 566                         $this->schema = $schema;
 567                 }
 568
 569                 return $old;
 570         }
 571
 572         public function getLBInfo( $name = null ) {
 573                 if ( is_null( $name ) ) {
 574                         return $this->lbInfo;
 575                 } else {
 576                         if ( array_key_exists( $name, $this->lbInfo ) ) {
 577                                 return $this->lbInfo[$name];
 578                         } else {
 579                                 return null;
 580                         }
 581                 }
 582         }
 583
 584         public function setLBInfo( $name, $value = null ) {
 585                 if ( is_null( $value ) ) {
 586                         $this->lbInfo = $name;
 587                 } else {
 588                         $this->lbInfo[$name] = $value;
 589                 }
 590         }
 591
 592         public function setLazyMasterHandle( IDatabase $conn ) {
 593                 $this->lazyMasterHandle = $conn;
 594         }
 595
 596         /**
 597          * @return IDatabase|null
 598          * @see setLazyMasterHandle()
 599          * @since 1.27
 600          */
 601         protected function getLazyMasterHandle() {
 602                 return $this->lazyMasterHandle;
 603         }
 604
 605         public function implicitGroupby() {
 606                 return true;
 607         }
 608
 609         public function implicitOrderby() {
 610                 return true;
 611         }
 612
 613         public function lastQuery() {
 614                 return $this->lastQuery;
 615         }
 616
 617         public function doneWrites() {
 618                 return (bool)$this->lastWriteTime;
 619         }
 620
 621         public function lastDoneWrites() {
 622                 return $this->lastWriteTime ?: false;
 623         }
 624
 625         public function writesPending() {
 626                 return $this->trxLevel && $this->trxDoneWrites;
 627         }
 628
 629         public function writesOrCallbacksPending() {
 630                 return $this->trxLevel && (
 631                         $this->trxDoneWrites ||
 632                         $this->trxIdleCallbacks ||
 633                         $this->trxPreCommitCallbacks ||
 634                         $this->trxEndCallbacks
 635                 );
 636         }
 637
 638         /**
 639          * @return string|null
 640          */
 641         final protected function getTransactionRoundId() {
 642                 // If transaction round participation is enabled, see if one is active
 643                 if ( $this->getFlag( self::DBO_TRX ) ) {
 644                         $id = $this->getLBInfo( 'trxRoundId' );
 645
 646                         return is_string( $id ) ? $id : null;
 647                 }
 648
 649                 return null;
 650         }
 651
 652         public function pendingWriteQueryDuration( $type = self::ESTIMATE_TOTAL ) {
 653                 if ( !$this->trxLevel ) {
 654                         return false;
 655                 } elseif ( !$this->trxDoneWrites ) {
 656                         return 0.0;
 657                 }
 658
 659                 switch ( $type ) {
 660                         case self::ESTIMATE_DB_APPLY:
 661                                 $this->ping( $rtt );
 662                                 $rttAdjTotal = $this->trxWriteAdjQueryCount * $rtt;
 663                                 $applyTime = max( $this->trxWriteAdjDuration - $rttAdjTotal, 0 );
 664                                 // For omitted queries, make them count as something at least
 665                                 $omitted = $this->trxWriteQueryCount - $this->trxWriteAdjQueryCount;
 666                                 $applyTime += self::TINY_WRITE_SEC * $omitted;
 667
 668                                 return $applyTime;
 669                         default: // everything
 670                                 return $this->trxWriteDuration;
 671                 }
 672         }
 673
 674         public function pendingWriteCallers() {
 675                 return $this->trxLevel ? $this->trxWriteCallers : [];
 676         }
 677
 678         public function pendingWriteRowsAffected() {
 679                 return $this->trxWriteAffectedRows;
 680         }
 681
 682         /**
 683          * Get the list of method names that have pending write queries or callbacks
 684          * for this transaction
 685          *
 686          * @return array
 687          */
 688         protected function pendingWriteAndCallbackCallers() {
 689                 if ( !$this->trxLevel ) {
 690                         return [];
 691                 }
 692
 693                 $fnames = $this->trxWriteCallers;
 694                 foreach ( [
 695                         $this->trxIdleCallbacks,
 696                         $this->trxPreCommitCallbacks,
 697                         $this->trxEndCallbacks
 698                 ] as $callbacks ) {
 699                         foreach ( $callbacks as $callback ) {
 700                                 $fnames[] = $callback[1];
 701                         }
 702                 }
 703
 704                 return $fnames;
 705         }
 706
 707         public function isOpen() {
 708                 return $this->opened;
 709         }
 710
 711         public function setFlag( $flag, $remember = self::REMEMBER_NOTHING ) {
 712                 if ( ( $flag & self::DBO_IGNORE ) ) {
 713                         throw new UnexpectedValueException( "Modifying DBO_IGNORE is not allowed." );
 714                 }
 715
 716                 if ( $remember === self::REMEMBER_PRIOR ) {
 717                         array_push( $this->priorFlags, $this->flags );
 718                 }
 719                 $this->flags |= $flag;
 720         }
 721
 722         public function clearFlag( $flag, $remember = self::REMEMBER_NOTHING ) {
 723                 if ( ( $flag & self::DBO_IGNORE ) ) {
 724                         throw new UnexpectedValueException( "Modifying DBO_IGNORE is not allowed." );
 725                 }
 726
 727                 if ( $remember === self::REMEMBER_PRIOR ) {
 728                         array_push( $this->priorFlags, $this->flags );
 729                 }
 730                 $this->flags &= ~$flag;
 731         }
 732
 733         public function restoreFlags( $state = self::RESTORE_PRIOR ) {
 734                 if ( !$this->priorFlags ) {
 735                         return;
 736                 }
 737
 738                 if ( $state === self::RESTORE_INITIAL ) {
 739                         $this->flags = reset( $this->priorFlags );
 740                         $this->priorFlags = [];
 741                 } else {
 742                         $this->flags = array_pop( $this->priorFlags );
 743                 }
 744         }
 745
 746         public function getFlag( $flag ) {
 747                 return !!( $this->flags & $flag );
 748         }
 749
 750         /**
 751          * @param string $name Class field name
 752          * @return mixed
 753          * @deprecated Since 1.28
 754          */
 755         public function getProperty( $name ) {
 756                 return $this->$name;
 757         }
 758
 759         public function getDomainID() {
 760                 return $this->currentDomain->getId();
 761         }
 762
 763         final public function getWikiID() {
 764                 return $this->getDomainID();
 765         }
 766
 767         /**
 768          * Get information about an index into an object
 769          * @param string $table Table name
 770          * @param string $index Index name
 771          * @param string $fname Calling function name
 772          * @return mixed Database-specific index description class or false if the index does not exist
 773          */
 774         abstract function indexInfo( $table, $index, $fname = __METHOD__ );
 775
 776         /**
 777          * Wrapper for addslashes()
 778          *
 779          * @param string $s String to be slashed.
 780          * @return string Slashed string.
 781          */
 782         abstract function strencode( $s );
 783
 784         /**
 785          * Set a custom error handler for logging errors during database connection
 786          */
 787         protected function installErrorHandler() {
 788                 $this->phpError = false;
 789                 $this->htmlErrors = ini_set( 'html_errors', '0' );
 790                 set_error_handler( [ $this, 'connectionErrorLogger' ] );
 791         }
 792
 793         /**
 794          * Restore the previous error handler and return the last PHP error for this DB
 795          *
 796          * @return bool|string
 797          */
 798         protected function restoreErrorHandler() {
 799                 restore_error_handler();
 800                 if ( $this->htmlErrors !== false ) {
 801                         ini_set( 'html_errors', $this->htmlErrors );
 802                 }
 803
 804                 return $this->getLastPHPError();
 805         }
 806
 807         /**
 808          * @return string|bool Last PHP error for this DB (typically connection errors)
 809          */
 810         protected function getLastPHPError() {
 811                 if ( $this->phpError ) {
 812                         $error = preg_replace( '!\[<a.*</a>\]!', '', $this->phpError );
 813                         $error = preg_replace( '!^.*?:\s?(.*)$!', '$1', $error );
 814
 815                         return $error;
 816                 }
 817
 818                 return false;
 819         }
 820
 821         /**
 822          * Error handler for logging errors during database connection
 823          * This method should not be used outside of Database classes
 824          *
 825          * @param int $errno
 826          * @param string $errstr
 827          */
 828         public function connectionErrorLogger( $errno, $errstr ) {
 829                 $this->phpError = $errstr;
 830         }
 831
 832         /**
 833          * Create a log context to pass to PSR-3 logger functions.
 834          *
 835          * @param array $extras Additional data to add to context
 836          * @return array
 837          */
 838         protected function getLogContext( array $extras = [] ) {
 839                 return array_merge(
 840                         [
 841                                 'db_server' => $this->server,
 842                                 'db_name' => $this->dbName,
 843                                 'db_user' => $this->user,
 844                         ],
 845                         $extras
 846                 );
 847         }
 848
 849         public function close() {
 850                 if ( $this->conn ) {
 851                         // Resolve any dangling transaction first
 852                         if ( $this->trxLevel() ) {
 853                                 // Meaningful transactions should ideally have been resolved by now
 854                                 if ( $this->writesOrCallbacksPending() ) {
 855                                         $this->queryLogger->warning(
 856                                                 __METHOD__ . ": writes or callbacks still pending.",
 857                                                 [ 'trace' => ( new RuntimeException() )->getTraceAsString() ]
 858                                         );
 859                                 }
 860                                 // Check if it is possible to properly commit and trigger callbacks
 861                                 if ( $this->trxEndCallbacksSuppressed ) {
 862                                         throw new DBUnexpectedError(
 863                                                 $this,
 864                                                 __METHOD__ . ': callbacks are suppressed; cannot properly commit.'
 865                                         );
 866                                 }
 867                                 // Commit the changes and run any callbacks as needed
 868                                 $this->commit( __METHOD__, self::FLUSHING_INTERNAL );
 869                         }
 870                         // Close the actual connection in the binding handle
 871                         $closed = $this->closeConnection();
 872                         $this->conn = false;
 873                         // Sanity check that no callbacks are dangling
 874                         if (
 875                                 $this->trxIdleCallbacks || $this->trxPreCommitCallbacks || $this->trxEndCallbacks
 876                         ) {
 877                                 throw new RuntimeException( "Transaction callbacks still pending." );
 878                         }
 879                 } else {
 880                         $closed = true; // already closed; nothing to do
 881                 }
 882
 883                 $this->opened = false;
 884
 885                 return $closed;
 886         }
 887
 888         /**
 889          * Make sure isOpen() returns true as a sanity check
 890          *
 891          * @throws DBUnexpectedError
 892          */
 893         protected function assertOpen() {
 894                 if ( !$this->isOpen() ) {
 895                         throw new DBUnexpectedError( $this, "DB connection was already closed." );
 896                 }
 897         }
 898
 899         /**
 900          * Closes underlying database connection
 901          * @since 1.20
 902          * @return bool Whether connection was closed successfully
 903          */
 904         abstract protected function closeConnection();
 905
 906         /**
 907          * @param string $error Fallback error message, used if none is given by DB
 908          * @throws DBConnectionError
 909          */
 910         public function reportConnectionError( $error = 'Unknown error' ) {
 911                 $myError = $this->lastError();
 912                 if ( $myError ) {
 913                         $error = $myError;
 914                 }
 915
 916                 # New method
 917                 throw new DBConnectionError( $this, $error );
 918         }
 919
 920         /**
 921          * Run a query and return a DBMS-dependent wrapper (that has all IResultWrapper methods)
 922          *
 923          * This might return things, such as mysqli_result, that do not formally implement
 924          * IResultWrapper, but nonetheless implement all of its methods correctly
 925          *
 926          * @param string $sql SQL query.
 927          * @return IResultWrapper|bool Iterator to feed to fetchObject/fetchRow; false on failure
 928          */
 929         abstract protected function doQuery( $sql );
 930
 931         /**
 932          * Determine whether a query writes to the DB.
 933          * Should return true if unsure.
 934          *
 935          * @param string $sql
 936          * @return bool
 937          */
 938         protected function isWriteQuery( $sql ) {
 939                 return !preg_match(
 940                         '/^(?:SELECT|BEGIN|ROLLBACK|COMMIT|SET|SHOW|EXPLAIN|\(SELECT)\b/i', $sql );
 941         }
 942
 943         /**
 944          * @param string $sql
 945          * @return string|null
 946          */
 947         protected function getQueryVerb( $sql ) {
 948                 return preg_match( '/^\s*([a-z]+)/i', $sql, $m ) ? strtoupper( $m[1] ) : null;
 949         }
 950
 951         /**
 952          * Determine whether a SQL statement is sensitive to isolation level.
 953          * A SQL statement is considered transactable if its result could vary
 954          * depending on the transaction isolation level. Operational commands
 955          * such as 'SET' and 'SHOW' are not considered to be transactable.
 956          *
 957          * @param string $sql
 958          * @return bool
 959          */
 960         protected function isTransactableQuery( $sql ) {
 961                 return !in_array(
 962                         $this->getQueryVerb( $sql ),
 963                         [ 'BEGIN', 'COMMIT', 'ROLLBACK', 'SHOW', 'SET', 'CREATE', 'ALTER' ],
 964                         true
 965                 );
 966         }
 967
 968         /**
 969          * @param string $sql A SQL query
 970          * @return bool Whether $sql is SQL for TEMPORARY table operation
 971          */
 972         protected function registerTempTableOperation( $sql ) {
 973                 if ( preg_match(
 974                         '/^CREATE\s+TEMPORARY\s+TABLE\s+(?:IF\s+NOT\s+EXISTS\s+)?[`"\']?(\w+)[`"\']?/i',
 975                         $sql,
 976                         $matches
 977                 ) ) {
 978                         $this->sessionTempTables[$matches[1]] = 1;
 979
 980                         return true;
 981                 } elseif ( preg_match(
 982                         '/^DROP\s+(?:TEMPORARY\s+)?TABLE\s+(?:IF\s+EXISTS\s+)?[`"\']?(\w+)[`"\']?/i',
 983                         $sql,
 984                         $matches
 985                 ) ) {
 986                         $isTemp = isset( $this->sessionTempTables[$matches[1]] );
 987                         unset( $this->sessionTempTables[$matches[1]] );
 988
 989                         return $isTemp;
 990                 } elseif ( preg_match(
 991                         '/^TRUNCATE\s+(?:TEMPORARY\s+)?TABLE\s+(?:IF\s+EXISTS\s+)?[`"\']?(\w+)[`"\']?/i',
 992                         $sql,
 993                         $matches
 994                 ) ) {
 995                         return isset( $this->sessionTempTables[$matches[1]] );
 996                 } elseif ( preg_match(
 997                         '/^(?:INSERT\s+(?:\w+\s+)?INTO|UPDATE|DELETE\s+FROM)\s+[`"\']?(\w+)[`"\']?/i',
 998                         $sql,
 999                         $matches
1000                 ) ) {
1001                         return isset( $this->sessionTempTables[$matches[1]] );
1002                 }
1003
1004                 return false;
1005         }
1006
1007         public function query( $sql, $fname = __METHOD__, $tempIgnore = false ) {
1008                 $priorWritesPending = $this->writesOrCallbacksPending();
1009                 $this->lastQuery = $sql;
1010
1011                 $isWrite = $this->isWriteQuery( $sql );
1012                 if ( $isWrite ) {
1013                         $isNonTempWrite = !$this->registerTempTableOperation( $sql );
1014                 } else {
1015                         $isNonTempWrite = false;
1016                 }
1017
1018                 if ( $isWrite ) {
1019                         if ( $this->getLBInfo( 'replica' ) === true ) {
1020                                 throw new DBError(
1021                                         $this,
1022                                         'Write operations are not allowed on replica database connections.'
1023                                 );
1024                         }
1025                         # In theory, non-persistent writes are allowed in read-only mode, but due to things
1026                         # like https://bugs.mysql.com/bug.php?id=33669 that might not work anyway...
1027                         $reason = $this->getReadOnlyReason();
1028                         if ( $reason !== false ) {
1029                                 throw new DBReadOnlyError( $this, "Database is read-only: $reason" );
1030                         }
1031                         # Set a flag indicating that writes have been done
1032                         $this->lastWriteTime = microtime( true );
1033                 }
1034
1035                 # Add trace comment to the begin of the sql string, right after the operator.
1036                 # Or, for one-word queries (like "BEGIN" or COMMIT") add it to the end (T44598)
1037                 $commentedSql = preg_replace( '/\s|$/', " /* $fname {$this->agent} */ ", $sql, 1 );
1038
1039                 # Start implicit transactions that wrap the request if DBO_TRX is enabled
1040                 if ( !$this->trxLevel && $this->getFlag( self::DBO_TRX )
1041                         && $this->isTransactableQuery( $sql )
1042                 ) {
1043                         $this->begin( __METHOD__ . " ($fname)", self::TRANSACTION_INTERNAL );
1044                         $this->trxAutomatic = true;
1045                 }
1046
1047                 # Keep track of whether the transaction has write queries pending
1048                 if ( $this->trxLevel && !$this->trxDoneWrites && $isWrite ) {
1049                         $this->trxDoneWrites = true;
1050                         $this->trxProfiler->transactionWritingIn(
1051                                 $this->server, $this->dbName, $this->trxShortId );
1052                 }
1053
1054                 if ( $this->getFlag( self::DBO_DEBUG ) ) {
1055                         $this->queryLogger->debug( "{$this->dbName} {$commentedSql}" );
1056                 }
1057
1058                 # Avoid fatals if close() was called
1059                 $this->assertOpen();
1060
1061                 # Send the query to the server and fetch any corresponding errors
1062                 $ret = $this->doProfiledQuery( $sql, $commentedSql, $isNonTempWrite, $fname );
1063                 $lastError = $this->lastError();
1064                 $lastErrno = $this->lastErrno();
1065
1066                 # Try reconnecting if the connection was lost
1067                 if ( $ret === false && $this->wasConnectionLoss() ) {
1068                         # Check if any meaningful session state was lost
1069                         $recoverable = $this->canRecoverFromDisconnect( $sql, $priorWritesPending );
1070                         # Update session state tracking and try to restore the connection
1071                         $reconnected = $this->replaceLostConnection( __METHOD__ );
1072                         # Silently resend the query to the server if it is safe and possible
1073                         if ( $reconnected && $recoverable ) {
1074                                 $ret = $this->doProfiledQuery( $sql, $commentedSql, $isNonTempWrite, $fname );
1075                                 $lastError = $this->lastError();
1076                                 $lastErrno = $this->lastErrno();
1077
1078                                 if ( $ret === false && $this->wasConnectionLoss() ) {
1079                                         # Query probably causes disconnects; reconnect and do not re-run it
1080                                         $this->replaceLostConnection( __METHOD__ );
1081                                 }
1082                         }
1083                 }
1084
1085                 if ( $ret === false ) {
1086                         # Deadlocks cause the entire transaction to abort, not just the statement.
1087                         # https://dev.mysql.com/doc/refman/5.7/en/innodb-error-handling.html
1088                         # https://www.postgresql.org/docs/9.1/static/explicit-locking.html
1089                         if ( $this->wasDeadlock() ) {
1090                                 if ( $this->explicitTrxActive() || $priorWritesPending ) {
1091                                         $tempIgnore = false; // not recoverable
1092                                 }
1093                                 # Usually the transaction is rolled back to BEGIN, leaving an empty transaction.
1094                                 # Destroy any such transaction so the rollback callbacks run in AUTO-COMMIT mode
1095                                 # as normal. Also, if DBO_TRX is set and an explicit transaction rolled back here,
1096                                 # further queries should be back in AUTO-COMMIT mode, not stuck in a transaction.
1097                                 $this->doRollback( __METHOD__ );
1098                                 # Update state tracking to reflect transaction loss
1099                                 $this->handleTransactionLoss();
1100                         }
1101
1102                         $this->reportQueryError( $lastError, $lastErrno, $sql, $fname, $tempIgnore );
1103                 }
1104
1105                 return $this->resultObject( $ret );
1106         }
1107
1108         /**
1109          * Wrapper for query() that also handles profiling, logging, and affected row count updates
1110          *
1111          * @param string $sql Original SQL query
1112          * @param string $commentedSql SQL query with debugging/trace comment
1113          * @param bool $isWrite Whether the query is a (non-temporary) write operation
1114          * @param string $fname Name of the calling function
1115          * @return bool|ResultWrapper True for a successful write query, ResultWrapper
1116          *     object for a successful read query, or false on failure
1117          */
1118         private function doProfiledQuery( $sql, $commentedSql, $isWrite, $fname ) {
1119                 $isMaster = !is_null( $this->getLBInfo( 'master' ) );
1120                 # generalizeSQL() will probably cut down the query to reasonable
1121                 # logging size most of the time. The substr is really just a sanity check.
1122                 if ( $isMaster ) {
1123                         $queryProf = 'query-m: ' . substr( self::generalizeSQL( $sql ), 0, 255 );
1124                 } else {
1125                         $queryProf = 'query: ' . substr( self::generalizeSQL( $sql ), 0, 255 );
1126                 }
1127
1128                 # Include query transaction state
1129                 $queryProf .= $this->trxShortId ? " [TRX#{$this->trxShortId}]" : "";
1130
1131                 $startTime = microtime( true );
1132                 if ( $this->profiler ) {
1133                         call_user_func( [ $this->profiler, 'profileIn' ], $queryProf );
1134                 }
1135                 $this->affectedRowCount = null;
1136                 $ret = $this->doQuery( $commentedSql );
1137                 $this->affectedRowCount = $this->affectedRows();
1138                 if ( $this->profiler ) {
1139                         call_user_func( [ $this->profiler, 'profileOut' ], $queryProf );
1140                 }
1141                 $queryRuntime = max( microtime( true ) - $startTime, 0.0 );
1142
1143                 unset( $queryProfSection ); // profile out (if set)
1144
1145                 if ( $ret !== false ) {
1146                         $this->lastPing = $startTime;
1147                         if ( $isWrite && $this->trxLevel ) {
1148                                 $this->updateTrxWriteQueryTime( $sql, $queryRuntime, $this->affectedRows() );
1149                                 $this->trxWriteCallers[] = $fname;
1150                         }
1151                 }
1152
1153                 if ( $sql === self::PING_QUERY ) {
1154                         $this->rttEstimate = $queryRuntime;
1155                 }
1156
1157                 $this->trxProfiler->recordQueryCompletion(
1158                         $queryProf, $startTime, $isWrite, $this->affectedRows()
1159                 );
1160                 $this->queryLogger->debug( $sql, [
1161                         'method' => $fname,
1162                         'master' => $isMaster,
1163                         'runtime' => $queryRuntime,
1164                 ] );
1165
1166                 return $ret;
1167         }
1168
1169         /**
1170          * Update the estimated run-time of a query, not counting large row lock times
1171          *
1172          * LoadBalancer can be set to rollback transactions that will create huge replication
1173          * lag. It bases this estimate off of pendingWriteQueryDuration(). Certain simple
1174          * queries, like inserting a row can take a long time due to row locking. This method
1175          * uses some simple heuristics to discount those cases.
1176          *
1177          * @param string $sql A SQL write query
1178          * @param float $runtime Total runtime, including RTT
1179          * @param int $affected Affected row count
1180          */
1181         private function updateTrxWriteQueryTime( $sql, $runtime, $affected ) {
1182                 // Whether this is indicative of replica DB runtime (except for RBR or ws_repl)
1183                 $indicativeOfReplicaRuntime = true;
1184                 if ( $runtime > self::SLOW_WRITE_SEC ) {
1185                         $verb = $this->getQueryVerb( $sql );
1186                         // insert(), upsert(), replace() are fast unless bulky in size or blocked on locks
1187                         if ( $verb === 'INSERT' ) {
1188                                 $indicativeOfReplicaRuntime = $this->affectedRows() > self::SMALL_WRITE_ROWS;
1189                         } elseif ( $verb === 'REPLACE' ) {
1190                                 $indicativeOfReplicaRuntime = $this->affectedRows() > self::SMALL_WRITE_ROWS / 2;
1191                         }
1192                 }
1193
1194                 $this->trxWriteDuration += $runtime;
1195                 $this->trxWriteQueryCount += 1;
1196                 $this->trxWriteAffectedRows += $affected;
1197                 if ( $indicativeOfReplicaRuntime ) {
1198                         $this->trxWriteAdjDuration += $runtime;
1199                         $this->trxWriteAdjQueryCount += 1;
1200                 }
1201         }
1202
1203         /**
1204          * Determine whether or not it is safe to retry queries after a database
1205          * connection is lost
1206          *
1207          * @param string $sql SQL query
1208          * @param bool $priorWritesPending Whether there is a transaction open with
1209          *     possible write queries or transaction pre-commit/idle callbacks
1210          *     waiting on it to finish.
1211          * @return bool True if it is safe to retry the query, false otherwise
1212          */
1213         private function canRecoverFromDisconnect( $sql, $priorWritesPending ) {
1214                 # Transaction dropped; this can mean lost writes, or REPEATABLE-READ snapshots.
1215                 # Dropped connections also mean that named locks are automatically released.
1216                 # Only allow error suppression in autocommit mode or when the lost transaction
1217                 # didn't matter anyway (aside from DBO_TRX snapshot loss).
1218                 if ( $this->namedLocksHeld ) {
1219                         return false; // possible critical section violation
1220                 } elseif ( $this->sessionTempTables ) {
1221                         return false; // tables might be queried latter
1222                 } elseif ( $sql === 'COMMIT' ) {
1223                         return !$priorWritesPending; // nothing written anyway? (T127428)
1224                 } elseif ( $sql === 'ROLLBACK' ) {
1225                         return true; // transaction lost...which is also what was requested :)
1226                 } elseif ( $this->explicitTrxActive() ) {
1227                         return false; // don't drop atomocity
1228                 } elseif ( $priorWritesPending ) {
1229                         return false; // prior writes lost from implicit transaction
1230                 }
1231
1232                 return true;
1233         }
1234
1235         /**
1236          * Clean things up after session (and thus transaction) loss
1237          */
1238         private function handleSessionLoss() {
1239                 // Clean up tracking of session-level things...
1240                 // https://dev.mysql.com/doc/refman/5.7/en/implicit-commit.html
1241                 // https://www.postgresql.org/docs/9.1/static/sql-createtable.html (ignoring ON COMMIT)
1242                 $this->sessionTempTables = [];
1243                 // https://dev.mysql.com/doc/refman/5.7/en/miscellaneous-functions.html#function_get-lock
1244                 // https://www.postgresql.org/docs/9.4/static/functions-admin.html#FUNCTIONS-ADVISORY-LOCKS
1245                 $this->namedLocksHeld = [];
1246                 // Session loss implies transaction loss
1247                 $this->handleTransactionLoss();
1248         }
1249
1250         /**
1251          * Clean things up after transaction loss
1252          */
1253         private function handleTransactionLoss() {
1254                 $this->trxLevel = 0;
1255                 $this->trxAtomicCounter = 0;
1256                 $this->trxIdleCallbacks = []; // T67263; transaction already lost
1257                 $this->trxPreCommitCallbacks = []; // T67263; transaction already lost
1258                 try {
1259                         // Handle callbacks in trxEndCallbacks, e.g. onTransactionResolution().
1260                         // If callback suppression is set then the array will remain unhandled.
1261                         $this->runOnTransactionIdleCallbacks( self::TRIGGER_ROLLBACK );
1262                 } catch ( Exception $ex ) {
1263                         // Already logged; move on...
1264                 }
1265                 try {
1266                         // Handle callbacks in trxRecurringCallbacks, e.g. setTransactionListener()
1267                         $this->runTransactionListenerCallbacks( self::TRIGGER_ROLLBACK );
1268                 } catch ( Exception $ex ) {
1269                         // Already logged; move on...
1270                 }
1271         }
1272
1273         /**
1274          * Checks whether the cause of the error is detected to be a timeout.
1275          *
1276          * It returns false by default, and not all engines support detecting this yet.
1277          * If this returns false, it will be treated as a generic query error.
1278          *
1279          * @param string $error Error text
1280          * @param int $errno Error number
1281          * @return bool
1282          */
1283         protected function wasQueryTimeout( $error, $errno ) {
1284                 return false;
1285         }
1286
1287         /**
1288          * Report a query error. Log the error, and if neither the object ignore
1289          * flag nor the $tempIgnore flag is set, throw a DBQueryError.
1290          *
1291          * @param string $error
1292          * @param int $errno
1293          * @param string $sql
1294          * @param string $fname
1295          * @param bool $tempIgnore
1296          * @throws DBQueryError
1297          */
1298         public function reportQueryError( $error, $errno, $sql, $fname, $tempIgnore = false ) {
1299                 if ( $tempIgnore ) {
1300                         $this->queryLogger->debug( "SQL ERROR (ignored): $error\n" );
1301                 } else {
1302                         $sql1line = mb_substr( str_replace( "\n", "\\n", $sql ), 0, 5 * 1024 );
1303                         $this->queryLogger->error(
1304                                 "{fname}\t{db_server}\t{errno}\t{error}\t{sql1line}",
1305                                 $this->getLogContext( [
1306                                         'method' => __METHOD__,
1307                                         'errno' => $errno,
1308                                         'error' => $error,
1309                                         'sql1line' => $sql1line,
1310                                         'fname' => $fname,
1311                                 ] )
1312                         );
1313                         $this->queryLogger->debug( "SQL ERROR: " . $error . "\n" );
1314                         $wasQueryTimeout = $this->wasQueryTimeout( $error, $errno );
1315                         if ( $wasQueryTimeout ) {
1316                                 throw new DBQueryTimeoutError( $this, $error, $errno, $sql, $fname );
1317                         } else {
1318                                 throw new DBQueryError( $this, $error, $errno, $sql, $fname );
1319                         }
1320                 }
1321         }
1322
1323         public function freeResult( $res ) {
1324         }
1325
1326         public function selectField(
1327                 $table, $var, $cond = '', $fname = __METHOD__, $options = [], $join_conds = []
1328         ) {
1329                 if ( $var === '*' ) { // sanity
1330                         throw new DBUnexpectedError( $this, "Cannot use a * field: got '$var'" );
1331                 }
1332
1333                 if ( !is_array( $options ) ) {
1334                         $options = [ $options ];
1335                 }
1336
1337                 $options['LIMIT'] = 1;
1338
1339                 $res = $this->select( $table, $var, $cond, $fname, $options, $join_conds );
1340                 if ( $res === false || !$this->numRows( $res ) ) {
1341                         return false;
1342                 }
1343
1344                 $row = $this->fetchRow( $res );
1345
1346                 if ( $row !== false ) {
1347                         return reset( $row );
1348                 } else {
1349                         return false;
1350                 }
1351         }
1352
1353         public function selectFieldValues(
1354                 $table, $var, $cond = '', $fname = __METHOD__, $options = [], $join_conds = []
1355         ) {
1356                 if ( $var === '*' ) { // sanity
1357                         throw new DBUnexpectedError( $this, "Cannot use a * field" );
1358                 } elseif ( !is_string( $var ) ) { // sanity
1359                         throw new DBUnexpectedError( $this, "Cannot use an array of fields" );
1360                 }
1361
1362                 if ( !is_array( $options ) ) {
1363                         $options = [ $options ];
1364                 }
1365
1366                 $res = $this->select( $table, $var, $cond, $fname, $options, $join_conds );
1367                 if ( $res === false ) {
1368                         return false;
1369                 }
1370
1371                 $values = [];
1372                 foreach ( $res as $row ) {
1373                         $values[] = $row->$var;
1374                 }
1375
1376                 return $values;
1377         }
1378
1379         /**
1380          * Returns an optional USE INDEX clause to go after the table, and a
1381          * string to go at the end of the query.
1382          *
1383          * @param array $options Associative array of options to be turned into
1384          *   an SQL query, valid keys are listed in the function.
1385          * @return array
1386          * @see Database::select()
1387          */
1388         protected function makeSelectOptions( $options ) {
1389                 $preLimitTail = $postLimitTail = '';
1390                 $startOpts = '';
1391
1392                 $noKeyOptions = [];
1393
1394                 foreach ( $options as $key => $option ) {
1395                         if ( is_numeric( $key ) ) {
1396                                 $noKeyOptions[$option] = true;
1397                         }
1398                 }
1399
1400                 $preLimitTail .= $this->makeGroupByWithHaving( $options );
1401
1402                 $preLimitTail .= $this->makeOrderBy( $options );
1403
1404                 if ( isset( $noKeyOptions['FOR UPDATE'] ) ) {
1405                         $postLimitTail .= ' FOR UPDATE';
1406                 }
1407
1408                 if ( isset( $noKeyOptions['LOCK IN SHARE MODE'] ) ) {
1409                         $postLimitTail .= ' LOCK IN SHARE MODE';
1410                 }
1411
1412                 if ( isset( $noKeyOptions['DISTINCT'] ) || isset( $noKeyOptions['DISTINCTROW'] ) ) {
1413                         $startOpts .= 'DISTINCT';
1414                 }
1415
1416                 # Various MySQL extensions
1417                 if ( isset( $noKeyOptions['STRAIGHT_JOIN'] ) ) {
1418                         $startOpts .= ' /*! STRAIGHT_JOIN */';
1419                 }
1420
1421                 if ( isset( $noKeyOptions['HIGH_PRIORITY'] ) ) {
1422                         $startOpts .= ' HIGH_PRIORITY';
1423                 }
1424
1425                 if ( isset( $noKeyOptions['SQL_BIG_RESULT'] ) ) {
1426                         $startOpts .= ' SQL_BIG_RESULT';
1427                 }
1428
1429                 if ( isset( $noKeyOptions['SQL_BUFFER_RESULT'] ) ) {
1430                         $startOpts .= ' SQL_BUFFER_RESULT';
1431                 }
1432
1433                 if ( isset( $noKeyOptions['SQL_SMALL_RESULT'] ) ) {
1434                         $startOpts .= ' SQL_SMALL_RESULT';
1435                 }
1436
1437                 if ( isset( $noKeyOptions['SQL_CALC_FOUND_ROWS'] ) ) {
1438                         $startOpts .= ' SQL_CALC_FOUND_ROWS';
1439                 }
1440
1441                 if ( isset( $noKeyOptions['SQL_CACHE'] ) ) {
1442                         $startOpts .= ' SQL_CACHE';
1443                 }
1444
1445                 if ( isset( $noKeyOptions['SQL_NO_CACHE'] ) ) {
1446                         $startOpts .= ' SQL_NO_CACHE';
1447                 }
1448
1449                 if ( isset( $options['USE INDEX'] ) && is_string( $options['USE INDEX'] ) ) {
1450                         $useIndex = $this->useIndexClause( $options['USE INDEX'] );
1451                 } else {
1452                         $useIndex = '';
1453                 }
1454                 if ( isset( $options['IGNORE INDEX'] ) && is_string( $options['IGNORE INDEX'] ) ) {
1455                         $ignoreIndex = $this->ignoreIndexClause( $options['IGNORE INDEX'] );
1456                 } else {
1457                         $ignoreIndex = '';
1458                 }
1459
1460                 return [ $startOpts, $useIndex, $preLimitTail, $postLimitTail, $ignoreIndex ];
1461         }
1462
1463         /**
1464          * Returns an optional GROUP BY with an optional HAVING
1465          *
1466          * @param array $options Associative array of options
1467          * @return string
1468          * @see Database::select()
1469          * @since 1.21
1470          */
1471         protected function makeGroupByWithHaving( $options ) {
1472                 $sql = '';
1473                 if ( isset( $options['GROUP BY'] ) ) {
1474                         $gb = is_array( $options['GROUP BY'] )
1475                                 ? implode( ',', $options['GROUP BY'] )
1476                                 : $options['GROUP BY'];
1477                         $sql .= ' GROUP BY ' . $gb;
1478                 }
1479                 if ( isset( $options['HAVING'] ) ) {
1480                         $having = is_array( $options['HAVING'] )
1481                                 ? $this->makeList( $options['HAVING'], self::LIST_AND )
1482                                 : $options['HAVING'];
1483                         $sql .= ' HAVING ' . $having;
1484                 }
1485
1486                 return $sql;
1487         }
1488
1489         /**
1490          * Returns an optional ORDER BY
1491          *
1492          * @param array $options Associative array of options
1493          * @return string
1494          * @see Database::select()
1495          * @since 1.21
1496          */
1497         protected function makeOrderBy( $options ) {
1498                 if ( isset( $options['ORDER BY'] ) ) {
1499                         $ob = is_array( $options['ORDER BY'] )
1500                                 ? implode( ',', $options['ORDER BY'] )
1501                                 : $options['ORDER BY'];
1502
1503                         return ' ORDER BY ' . $ob;
1504                 }
1505
1506                 return '';
1507         }
1508
1509         public function select( $table, $vars, $conds = '', $fname = __METHOD__,
1510                 $options = [], $join_conds = [] ) {
1511                 $sql = $this->selectSQLText( $table, $vars, $conds, $fname, $options, $join_conds );
1512
1513                 return $this->query( $sql, $fname );
1514         }
1515
1516         public function selectSQLText( $table, $vars, $conds = '', $fname = __METHOD__,
1517                 $options = [], $join_conds = []
1518         ) {
1519                 if ( is_array( $vars ) ) {
1520                         $vars = implode( ',', $this->fieldNamesWithAlias( $vars ) );
1521                 }
1522
1523                 $options = (array)$options;
1524                 $useIndexes = ( isset( $options['USE INDEX'] ) && is_array( $options['USE INDEX'] ) )
1525                         ? $options['USE INDEX']
1526                         : [];
1527                 $ignoreIndexes = (
1528                         isset( $options['IGNORE INDEX'] ) &&
1529                         is_array( $options['IGNORE INDEX'] )
1530                 )
1531                         ? $options['IGNORE INDEX']
1532                         : [];
1533
1534                 if ( is_array( $table ) ) {
1535                         $from = ' FROM ' .
1536                                 $this->tableNamesWithIndexClauseOrJOIN(
1537                                         $table, $useIndexes, $ignoreIndexes, $join_conds );
1538                 } elseif ( $table != '' ) {
1539                         $from = ' FROM ' .
1540                                 $this->tableNamesWithIndexClauseOrJOIN(
1541                                         [ $table ], $useIndexes, $ignoreIndexes, [] );
1542                 } else {
1543                         $from = '';
1544                 }
1545
1546                 list( $startOpts, $useIndex, $preLimitTail, $postLimitTail, $ignoreIndex ) =
1547                         $this->makeSelectOptions( $options );
1548
1549                 if ( is_array( $conds ) ) {
1550                         $conds = $this->makeList( $conds, self::LIST_AND );
1551                 }
1552
1553                 if ( $conds === null || $conds === false ) {
1554                         $this->queryLogger->warning(
1555                                 __METHOD__
1556                                 . ' called from '
1557                                 . $fname
1558                                 . ' with incorrect parameters: $conds must be a string or an array'
1559                         );
1560                         $conds = '';
1561                 }
1562
1563                 if ( $conds === '' ) {
1564                         $sql = "SELECT $startOpts $vars $from $useIndex $ignoreIndex $preLimitTail";
1565                 } elseif ( is_string( $conds ) ) {
1566                         $sql = "SELECT $startOpts $vars $from $useIndex $ignoreIndex " .
1567                                 "WHERE $conds $preLimitTail";
1568                 } else {
1569                         throw new DBUnexpectedError( $this, __METHOD__ . ' called with incorrect parameters' );
1570                 }
1571
1572                 if ( isset( $options['LIMIT'] ) ) {
1573                         $sql = $this->limitResult( $sql, $options['LIMIT'],
1574                                 isset( $options['OFFSET'] ) ? $options['OFFSET'] : false );
1575                 }
1576                 $sql = "$sql $postLimitTail";
1577
1578                 if ( isset( $options['EXPLAIN'] ) ) {
1579                         $sql = 'EXPLAIN ' . $sql;
1580                 }
1581
1582                 return $sql;
1583         }
1584
1585         public function selectRow( $table, $vars, $conds, $fname = __METHOD__,
1586                 $options = [], $join_conds = []
1587         ) {
1588                 $options = (array)$options;
1589                 $options['LIMIT'] = 1;
1590                 $res = $this->select( $table, $vars, $conds, $fname, $options, $join_conds );
1591
1592                 if ( $res === false ) {
1593                         return false;
1594                 }
1595
1596                 if ( !$this->numRows( $res ) ) {
1597                         return false;
1598                 }
1599
1600                 $obj = $this->fetchObject( $res );
1601
1602                 return $obj;
1603         }
1604
1605         public function estimateRowCount(
1606                 $table, $var = '*', $conds = '', $fname = __METHOD__, $options = [], $join_conds = []
1607         ) {
1608                 $conds = $this->normalizeConditions( $conds, $fname );
1609                 $column = $this->extractSingleFieldFromList( $var );
1610                 if ( is_string( $column ) && !in_array( $column, [ '*', '1' ] ) ) {
1611                         $conds[] = "$column IS NOT NULL";
1612                 }
1613
1614                 $res = $this->select(
1615                         $table, [ 'rowcount' => 'COUNT(*)' ], $conds, $fname, $options, $join_conds
1616                 );
1617                 $row = $res ? $this->fetchRow( $res ) : [];
1618
1619                 return isset( $row['rowcount'] ) ? (int)$row['rowcount'] : 0;
1620         }
1621
1622         public function selectRowCount(
1623                 $tables, $var = '*', $conds = '', $fname = __METHOD__, $options = [], $join_conds = []
1624         ) {
1625                 $conds = $this->normalizeConditions( $conds, $fname );
1626                 $column = $this->extractSingleFieldFromList( $var );
1627                 if ( is_string( $column ) && !in_array( $column, [ '*', '1' ] ) ) {
1628                         $conds[] = "$column IS NOT NULL";
1629                 }
1630
1631                 $res = $this->select(
1632                         [
1633                                 'tmp_count' => $this->buildSelectSubquery(
1634                                         $tables,
1635                                         '1',
1636                                         $conds,
1637                                         $fname,
1638                                         $options,
1639                                         $join_conds
1640                                 )
1641                         ],
1642                         [ 'rowcount' => 'COUNT(*)' ],
1643                         [],
1644                         $fname
1645                 );
1646                 $row = $res ? $this->fetchRow( $res ) : [];
1647
1648                 return isset( $row['rowcount'] ) ? (int)$row['rowcount'] : 0;
1649         }
1650
1651         /**
1652          * @param array|string $conds
1653          * @param string $fname
1654          * @return array
1655          */
1656         final protected function normalizeConditions( $conds, $fname ) {
1657                 if ( $conds === null || $conds === false ) {
1658                         $this->queryLogger->warning(
1659                                 __METHOD__
1660                                 . ' called from '
1661                                 . $fname
1662                                 . ' with incorrect parameters: $conds must be a string or an array'
1663                         );
1664                         $conds = '';
1665                 }
1666
1667                 if ( !is_array( $conds ) ) {
1668                         $conds = ( $conds === '' ) ? [] : [ $conds ];
1669                 }
1670
1671                 return $conds;
1672         }
1673
1674         /**
1675          * @param array|string $var Field parameter in the style of select()
1676          * @return string|null Column name or null; ignores aliases
1677          * @throws DBUnexpectedError Errors out if multiple columns are given
1678          */
1679         final protected function extractSingleFieldFromList( $var ) {
1680                 if ( is_array( $var ) ) {
1681                         if ( !$var ) {
1682                                 $column = null;
1683                         } elseif ( count( $var ) == 1 ) {
1684                                 $column = isset( $var[0] ) ? $var[0] : reset( $var );
1685                         } else {
1686                                 throw new DBUnexpectedError( $this, __METHOD__ . ': got multiple columns.' );
1687                         }
1688                 } else {
1689                         $column = $var;
1690                 }
1691
1692                 return $column;
1693         }
1694
1695         /**
1696          * Removes most variables from an SQL query and replaces them with X or N for numbers.
1697          * It's only slightly flawed. Don't use for anything important.
1698          *
1699          * @param string $sql A SQL Query
1700          *
1701          * @return string
1702          */
1703         protected static function generalizeSQL( $sql ) {
1704                 # This does the same as the regexp below would do, but in such a way
1705                 # as to avoid crashing php on some large strings.
1706                 # $sql = preg_replace( "/'([^\\\\']|\\\\.)*'|\"([^\\\\\"]|\\\\.)*\"/", "'X'", $sql );
1707
1708                 $sql = str_replace( "\\\\", '', $sql );
1709                 $sql = str_replace( "\\'", '', $sql );
1710                 $sql = str_replace( "\\\"", '', $sql );
1711                 $sql = preg_replace( "/'.*'/s", "'X'", $sql );
1712                 $sql = preg_replace( '/".*"/s', "'X'", $sql );
1713
1714                 # All newlines, tabs, etc replaced by single space
1715                 $sql = preg_replace( '/\s+/', ' ', $sql );
1716
1717                 # All numbers => N,
1718                 # except the ones surrounded by characters, e.g. l10n
1719                 $sql = preg_replace( '/-?\d+(,-?\d+)+/s', 'N,...,N', $sql );
1720                 $sql = preg_replace( '/(?<![a-zA-Z])-?\d+(?![a-zA-Z])/s', 'N', $sql );
1721
1722                 return $sql;
1723         }
1724
1725         public function fieldExists( $table, $field, $fname = __METHOD__ ) {
1726                 $info = $this->fieldInfo( $table, $field );
1727
1728                 return (bool)$info;
1729         }
1730
1731         public function indexExists( $table, $index, $fname = __METHOD__ ) {
1732                 if ( !$this->tableExists( $table ) ) {
1733                         return null;
1734                 }
1735
1736                 $info = $this->indexInfo( $table, $index, $fname );
1737                 if ( is_null( $info ) ) {
1738                         return null;
1739                 } else {
1740                         return $info !== false;
1741                 }
1742         }
1743
1744         public function tableExists( $table, $fname = __METHOD__ ) {
1745                 $tableRaw = $this->tableName( $table, 'raw' );
1746                 if ( isset( $this->sessionTempTables[$tableRaw] ) ) {
1747                         return true; // already known to exist
1748                 }
1749
1750                 $table = $this->tableName( $table );
1751                 $ignoreErrors = true;
1752                 $res = $this->query( "SELECT 1 FROM $table LIMIT 1", $fname, $ignoreErrors );
1753
1754                 return (bool)$res;
1755         }
1756
1757         public function indexUnique( $table, $index ) {
1758                 $indexInfo = $this->indexInfo( $table, $index );
1759
1760                 if ( !$indexInfo ) {
1761                         return null;
1762                 }
1763
1764                 return !$indexInfo[0]->Non_unique;
1765         }
1766
1767         /**
1768          * Helper for Database::insert().
1769          *
1770          * @param array $options
1771          * @return string
1772          */
1773         protected function makeInsertOptions( $options ) {
1774                 return implode( ' ', $options );
1775         }
1776
1777         public function insert( $table, $a, $fname = __METHOD__, $options = [] ) {
1778                 # No rows to insert, easy just return now
1779                 if ( !count( $a ) ) {
1780                         return true;
1781                 }
1782
1783                 $table = $this->tableName( $table );
1784
1785                 if ( !is_array( $options ) ) {
1786                         $options = [ $options ];
1787                 }
1788
1789                 $fh = null;
1790                 if ( isset( $options['fileHandle'] ) ) {
1791                         $fh = $options['fileHandle'];
1792                 }
1793                 $options = $this->makeInsertOptions( $options );
1794
1795                 if ( isset( $a[0] ) && is_array( $a[0] ) ) {
1796                         $multi = true;
1797                         $keys = array_keys( $a[0] );
1798                 } else {
1799                         $multi = false;
1800                         $keys = array_keys( $a );
1801                 }
1802
1803                 $sql = 'INSERT ' . $options .
1804                         " INTO $table (" . implode( ',', $keys ) . ') VALUES ';
1805
1806                 if ( $multi ) {
1807                         $first = true;
1808                         foreach ( $a as $row ) {
1809                                 if ( $first ) {
1810                                         $first = false;
1811                                 } else {
1812                                         $sql .= ',';
1813                                 }
1814                                 $sql .= '(' . $this->makeList( $row ) . ')';
1815                         }
1816                 } else {
1817                         $sql .= '(' . $this->makeList( $a ) . ')';
1818                 }
1819
1820                 if ( $fh !== null && false === fwrite( $fh, $sql ) ) {
1821                         return false;
1822                 } elseif ( $fh !== null ) {
1823                         return true;
1824                 }
1825
1826                 return (bool)$this->query( $sql, $fname );
1827         }
1828
1829         /**
1830          * Make UPDATE options array for Database::makeUpdateOptions
1831          *
1832          * @param array $options
1833          * @return array
1834          */
1835         protected function makeUpdateOptionsArray( $options ) {
1836                 if ( !is_array( $options ) ) {
1837                         $options = [ $options ];
1838                 }
1839
1840                 $opts = [];
1841
1842                 if ( in_array( 'IGNORE', $options ) ) {
1843                         $opts[] = 'IGNORE';
1844                 }
1845
1846                 return $opts;
1847         }
1848
1849         /**
1850          * Make UPDATE options for the Database::update function
1851          *
1852          * @param array $options The options passed to Database::update
1853          * @return string
1854          */
1855         protected function makeUpdateOptions( $options ) {
1856                 $opts = $this->makeUpdateOptionsArray( $options );
1857
1858                 return implode( ' ', $opts );
1859         }
1860
1861         public function update( $table, $values, $conds, $fname = __METHOD__, $options = [] ) {
1862                 $table = $this->tableName( $table );
1863                 $opts = $this->makeUpdateOptions( $options );
1864                 $sql = "UPDATE $opts $table SET " . $this->makeList( $values, self::LIST_SET );
1865
1866                 if ( $conds !== [] && $conds !== '*' ) {
1867                         $sql .= " WHERE " . $this->makeList( $conds, self::LIST_AND );
1868                 }
1869
1870                 return (bool)$this->query( $sql, $fname );
1871         }
1872
1873         public function makeList( $a, $mode = self::LIST_COMMA ) {
1874                 if ( !is_array( $a ) ) {
1875                         throw new DBUnexpectedError( $this, __METHOD__ . ' called with incorrect parameters' );
1876                 }
1877
1878                 $first = true;
1879                 $list = '';
1880
1881                 foreach ( $a as $field => $value ) {
1882                         if ( !$first ) {
1883                                 if ( $mode == self::LIST_AND ) {
1884                                         $list .= ' AND ';
1885                                 } elseif ( $mode == self::LIST_OR ) {
1886                                         $list .= ' OR ';
1887                                 } else {
1888                                         $list .= ',';
1889                                 }
1890                         } else {
1891                                 $first = false;
1892                         }
1893
1894                         if ( ( $mode == self::LIST_AND || $mode == self::LIST_OR ) && is_numeric( $field ) ) {
1895                                 $list .= "($value)";
1896                         } elseif ( $mode == self::LIST_SET && is_numeric( $field ) ) {
1897                                 $list .= "$value";
1898                         } elseif (
1899                                 ( $mode == self::LIST_AND || $mode == self::LIST_OR ) && is_array( $value )
1900                         ) {
1901                                 // Remove null from array to be handled separately if found
1902                                 $includeNull = false;
1903                                 foreach ( array_keys( $value, null, true ) as $nullKey ) {
1904                                         $includeNull = true;
1905                                         unset( $value[$nullKey] );
1906                                 }
1907                                 if ( count( $value ) == 0 && !$includeNull ) {
1908                                         throw new InvalidArgumentException(
1909                                                 __METHOD__ . ": empty input for field $field" );
1910                                 } elseif ( count( $value ) == 0 ) {
1911                                         // only check if $field is null
1912                                         $list .= "$field IS NULL";
1913                                 } else {
1914                                         // IN clause contains at least one valid element
1915                                         if ( $includeNull ) {
1916                                                 // Group subconditions to ensure correct precedence
1917                                                 $list .= '(';
1918                                         }
1919                                         if ( count( $value ) == 1 ) {
1920                                                 // Special-case single values, as IN isn't terribly efficient
1921                                                 // Don't necessarily assume the single key is 0; we don't
1922                                                 // enforce linear numeric ordering on other arrays here.
1923                                                 $value = array_values( $value )[0];
1924                                                 $list .= $field . " = " . $this->addQuotes( $value );
1925                                         } else {
1926                                                 $list .= $field . " IN (" . $this->makeList( $value ) . ") ";
1927                                         }
1928                                         // if null present in array, append IS NULL
1929                                         if ( $includeNull ) {
1930                                                 $list .= " OR $field IS NULL)";
1931                                         }
1932                                 }
1933                         } elseif ( $value === null ) {
1934                                 if ( $mode == self::LIST_AND || $mode == self::LIST_OR ) {
1935                                         $list .= "$field IS ";
1936                                 } elseif ( $mode == self::LIST_SET ) {
1937                                         $list .= "$field = ";
1938                                 }
1939                                 $list .= 'NULL';
1940                         } else {
1941                                 if (
1942                                         $mode == self::LIST_AND || $mode == self::LIST_OR || $mode == self::LIST_SET
1943                                 ) {
1944                                         $list .= "$field = ";
1945                                 }
1946                                 $list .= $mode == self::LIST_NAMES ? $value : $this->addQuotes( $value );
1947                         }
1948                 }
1949
1950                 return $list;
1951         }
1952
1953         public function makeWhereFrom2d( $data, $baseKey, $subKey ) {
1954                 $conds = [];
1955
1956                 foreach ( $data as $base => $sub ) {
1957                         if ( count( $sub ) ) {
1958                                 $conds[] = $this->makeList(
1959                                         [ $baseKey => $base, $subKey => array_keys( $sub ) ],
1960                                         self::LIST_AND );
1961                         }
1962                 }
1963
1964                 if ( $conds ) {
1965                         return $this->makeList( $conds, self::LIST_OR );
1966                 } else {
1967                         // Nothing to search for...
1968                         return false;
1969                 }
1970         }
1971
1972         public function aggregateValue( $valuedata, $valuename = 'value' ) {
1973                 return $valuename;
1974         }
1975
1976         public function bitNot( $field ) {
1977                 return "(~$field)";
1978         }
1979
1980         public function bitAnd( $fieldLeft, $fieldRight ) {
1981                 return "($fieldLeft & $fieldRight)";
1982         }
1983
1984         public function bitOr( $fieldLeft, $fieldRight ) {
1985                 return "($fieldLeft | $fieldRight)";
1986         }
1987
1988         public function buildConcat( $stringList ) {
1989                 return 'CONCAT(' . implode( ',', $stringList ) . ')';
1990         }
1991
1992         public function buildGroupConcatField(
1993                 $delim, $table, $field, $conds = '', $join_conds = []
1994         ) {
1995                 $fld = "GROUP_CONCAT($field SEPARATOR " . $this->addQuotes( $delim ) . ')';
1996
1997                 return '(' . $this->selectSQLText( $table, $fld, $conds, null, [], $join_conds ) . ')';
1998         }
1999
2000         public function buildSubstring( $input, $startPosition, $length = null ) {
2001                 $this->assertBuildSubstringParams( $startPosition, $length );
2002                 $functionBody = "$input FROM $startPosition";
2003                 if ( $length !== null ) {
2004                         $functionBody .= " FOR $length";
2005                 }
2006                 return 'SUBSTRING(' . $functionBody . ')';
2007         }
2008
2009         /**
2010          * Check type and bounds for parameters to self::buildSubstring()
2011          *
2012          * All supported databases have substring functions that behave the same for
2013          * positive $startPosition and non-negative $length, but behaviors differ when
2014          * given 0 or negative $startPosition or negative $length. The simplest
2015          * solution to that is to just forbid those values.
2016          *
2017          * @param int $startPosition
2018          * @param int|null $length
2019          * @since 1.31
2020          */
2021         protected function assertBuildSubstringParams( $startPosition, $length ) {
2022                 if ( !is_int( $startPosition ) || $startPosition <= 0 ) {
2023                         throw new InvalidArgumentException(
2024                                 '$startPosition must be a positive integer'
2025                         );
2026                 }
2027                 if ( !( is_int( $length ) && $length >= 0 || $length === null ) ) {
2028                         throw new InvalidArgumentException(
2029                                 '$length must be null or an integer greater than or equal to 0'
2030                         );
2031                 }
2032         }
2033
2034         public function buildStringCast( $field ) {
2035                 return $field;
2036         }
2037
2038         public function buildIntegerCast( $field ) {
2039                 return 'CAST( ' . $field . ' AS INTEGER )';
2040         }
2041
2042         public function buildSelectSubquery(
2043                 $table, $vars, $conds = '', $fname = __METHOD__,
2044                 $options = [], $join_conds = []
2045         ) {
2046                 return new Subquery(
2047                         $this->selectSQLText( $table, $vars, $conds, $fname, $options, $join_conds )
2048                 );
2049         }
2050
2051         public function databasesAreIndependent() {
2052                 return false;
2053         }
2054
2055         public function selectDB( $db ) {
2056                 # Stub. Shouldn't cause serious problems if it's not overridden, but
2057                 # if your database engine supports a concept similar to MySQL's
2058                 # databases you may as well.
2059                 $this->dbName = $db;
2060
2061                 return true;
2062         }
2063
2064         public function getDBname() {
2065                 return $this->dbName;
2066         }
2067
2068         public function getServer() {
2069                 return $this->server;
2070         }
2071
2072         public function tableName( $name, $format = 'quoted' ) {
2073                 if ( $name instanceof Subquery ) {
2074                         throw new DBUnexpectedError(
2075                                 $this,
2076                                 __METHOD__ . ': got Subquery instance when expecting a string.'
2077                         );
2078                 }
2079
2080                 # Skip the entire process when we have a string quoted on both ends.
2081                 # Note that we check the end so that we will still quote any use of
2082                 # use of `database`.table. But won't break things if someone wants
2083                 # to query a database table with a dot in the name.
2084                 if ( $this->isQuotedIdentifier( $name ) ) {
2085                         return $name;
2086                 }
2087
2088                 # Lets test for any bits of text that should never show up in a table
2089                 # name. Basically anything like JOIN or ON which are actually part of
2090                 # SQL queries, but may end up inside of the table value to combine
2091                 # sql. Such as how the API is doing.
2092                 # Note that we use a whitespace test rather than a \b test to avoid
2093                 # any remote case where a word like on may be inside of a table name
2094                 # surrounded by symbols which may be considered word breaks.
2095                 if ( preg_match( '/(^|\s)(DISTINCT|JOIN|ON|AS)(\s|$)/i', $name ) !== 0 ) {
2096                         $this->queryLogger->warning(
2097                                 __METHOD__ . ": use of subqueries is not supported this way.",
2098                                 [ 'trace' => ( new RuntimeException() )->getTraceAsString() ]
2099                         );
2100
2101                         return $name;
2102                 }
2103
2104                 # Split database and table into proper variables.
2105                 list( $database, $schema, $prefix, $table ) = $this->qualifiedTableComponents( $name );
2106
2107                 # Quote $table and apply the prefix if not quoted.
2108                 # $tableName might be empty if this is called from Database::replaceVars()
2109                 $tableName = "{$prefix}{$table}";
2110                 if ( $format === 'quoted'
2111                         && !$this->isQuotedIdentifier( $tableName )
2112                         && $tableName !== ''
2113                 ) {
2114                         $tableName = $this->addIdentifierQuotes( $tableName );
2115                 }
2116
2117                 # Quote $schema and $database and merge them with the table name if needed
2118                 $tableName = $this->prependDatabaseOrSchema( $schema, $tableName, $format );
2119                 $tableName = $this->prependDatabaseOrSchema( $database, $tableName, $format );
2120
2121                 return $tableName;
2122         }
2123
2124         /**
2125          * Get the table components needed for a query given the currently selected database
2126          *
2127          * @param string $name Table name in the form of db.schema.table, db.table, or table
2128          * @return array (DB name or "" for default, schema name, table prefix, table name)
2129          */
2130         protected function qualifiedTableComponents( $name ) {
2131                 # We reverse the explode so that database.table and table both output the correct table.
2132                 $dbDetails = explode( '.', $name, 3 );
2133                 if ( count( $dbDetails ) == 3 ) {
2134                         list( $database, $schema, $table ) = $dbDetails;
2135                         # We don't want any prefix added in this case
2136                         $prefix = '';
2137                 } elseif ( count( $dbDetails ) == 2 ) {
2138                         list( $database, $table ) = $dbDetails;
2139                         # We don't want any prefix added in this case
2140                         $prefix = '';
2141                         # In dbs that support it, $database may actually be the schema
2142                         # but that doesn't affect any of the functionality here
2143                         $schema = '';
2144                 } else {
2145                         list( $table ) = $dbDetails;
2146                         if ( isset( $this->tableAliases[$table] ) ) {
2147                                 $database = $this->tableAliases[$table]['dbname'];
2148                                 $schema = is_string( $this->tableAliases[$table]['schema'] )
2149                                         ? $this->tableAliases[$table]['schema']
2150                                         : $this->schema;
2151                                 $prefix = is_string( $this->tableAliases[$table]['prefix'] )
2152                                         ? $this->tableAliases[$table]['prefix']
2153                                         : $this->tablePrefix;
2154                         } else {
2155                                 $database = '';
2156                                 $schema = $this->schema; # Default schema
2157                                 $prefix = $this->tablePrefix; # Default prefix
2158                         }
2159                 }
2160
2161                 return [ $database, $schema, $prefix, $table ];
2162         }
2163
2164         /**
2165          * @param string|null $namespace Database or schema
2166          * @param string $relation Name of table, view, sequence, etc...
2167          * @param string $format One of (raw, quoted)
2168          * @return string Relation name with quoted and merged $namespace as needed
2169          */
2170         private function prependDatabaseOrSchema( $namespace, $relation, $format ) {
2171                 if ( strlen( $namespace ) ) {
2172                         if ( $format === 'quoted' && !$this->isQuotedIdentifier( $namespace ) ) {
2173                                 $namespace = $this->addIdentifierQuotes( $namespace );
2174                         }
2175                         $relation = $namespace . '.' . $relation;
2176                 }
2177
2178                 return $relation;
2179         }
2180
2181         public function tableNames() {
2182                 $inArray = func_get_args();
2183                 $retVal = [];
2184
2185                 foreach ( $inArray as $name ) {
2186                         $retVal[$name] = $this->tableName( $name );
2187                 }
2188
2189                 return $retVal;
2190         }
2191
2192         public function tableNamesN() {
2193                 $inArray = func_get_args();
2194                 $retVal = [];
2195
2196                 foreach ( $inArray as $name ) {
2197                         $retVal[] = $this->tableName( $name );
2198                 }
2199
2200                 return $retVal;
2201         }
2202
2203         /**
2204          * Get an aliased table name
2205          *
2206          * This returns strings like "tableName AS newTableName" for aliased tables
2207          * and "(SELECT * from tableA) newTablename" for subqueries (e.g. derived tables)
2208          *
2209          * @see Database::tableName()
2210          * @param string|Subquery $table Table name or object with a 'sql' field
2211          * @param string|bool $alias Table alias (optional)
2212          * @return string SQL name for aliased table. Will not alias a table to its own name
2213          */
2214         protected function tableNameWithAlias( $table, $alias = false ) {
2215                 if ( is_string( $table ) ) {
2216                         $quotedTable = $this->tableName( $table );
2217                 } elseif ( $table instanceof Subquery ) {
2218                         $quotedTable = (string)$table;
2219                 } else {
2220                         throw new InvalidArgumentException( "Table must be a string or Subquery." );
2221                 }
2222
2223                 if ( !strlen( $alias ) || $alias === $table ) {
2224                         if ( $table instanceof Subquery ) {
2225                                 throw new InvalidArgumentException( "Subquery table missing alias." );
2226                         }
2227
2228                         return $quotedTable;
2229                 } else {
2230                         return $quotedTable . ' ' . $this->addIdentifierQuotes( $alias );
2231                 }
2232         }
2233
2234         /**
2235          * Gets an array of aliased table names
2236          *
2237          * @param array $tables [ [alias] => table ]
2238          * @return string[] See tableNameWithAlias()
2239          */
2240         protected function tableNamesWithAlias( $tables ) {
2241                 $retval = [];
2242                 foreach ( $tables as $alias => $table ) {
2243                         if ( is_numeric( $alias ) ) {
2244                                 $alias = $table;
2245                         }
2246                         $retval[] = $this->tableNameWithAlias( $table, $alias );
2247                 }
2248
2249                 return $retval;
2250         }
2251
2252         /**
2253          * Get an aliased field name
2254          * e.g. fieldName AS newFieldName
2255          *
2256          * @param string $name Field name
2257          * @param string|bool $alias Alias (optional)
2258          * @return string SQL name for aliased field. Will not alias a field to its own name
2259          */
2260         protected function fieldNameWithAlias( $name, $alias = false ) {
2261                 if ( !$alias || (string)$alias === (string)$name ) {
2262                         return $name;
2263                 } else {
2264                         return $name . ' AS ' . $this->addIdentifierQuotes( $alias ); // PostgreSQL needs AS
2265                 }
2266         }
2267
2268         /**
2269          * Gets an array of aliased field names
2270          *
2271          * @param array $fields [ [alias] => field ]
2272          * @return string[] See fieldNameWithAlias()
2273          */
2274         protected function fieldNamesWithAlias( $fields ) {
2275                 $retval = [];
2276                 foreach ( $fields as $alias => $field ) {
2277                         if ( is_numeric( $alias ) ) {
2278                                 $alias = $field;
2279                         }
2280                         $retval[] = $this->fieldNameWithAlias( $field, $alias );
2281                 }
2282
2283                 return $retval;
2284         }
2285
2286         /**
2287          * Get the aliased table name clause for a FROM clause
2288          * which might have a JOIN and/or USE INDEX or IGNORE INDEX clause
2289          *
2290          * @param array $tables ( [alias] => table )
2291          * @param array $use_index Same as for select()
2292          * @param array $ignore_index Same as for select()
2293          * @param array $join_conds Same as for select()
2294          * @return string
2295          */
2296         protected function tableNamesWithIndexClauseOrJOIN(
2297                 $tables, $use_index = [], $ignore_index = [], $join_conds = []
2298         ) {
2299                 $ret = [];
2300                 $retJOIN = [];
2301                 $use_index = (array)$use_index;
2302                 $ignore_index = (array)$ignore_index;
2303                 $join_conds = (array)$join_conds;
2304
2305                 foreach ( $tables as $alias => $table ) {
2306                         if ( !is_string( $alias ) ) {
2307                                 // No alias? Set it equal to the table name
2308                                 $alias = $table;
2309                         }
2310
2311                         if ( is_array( $table ) ) {
2312                                 // A parenthesized group
2313                                 if ( count( $table ) > 1 ) {
2314                                         $joinedTable = '(' .
2315                                                 $this->tableNamesWithIndexClauseOrJOIN(
2316                                                         $table, $use_index, $ignore_index, $join_conds ) . ')';
2317                                 } else {
2318                                         // Degenerate case
2319                                         $innerTable = reset( $table );
2320                                         $innerAlias = key( $table );
2321                                         $joinedTable = $this->tableNameWithAlias(
2322                                                 $innerTable,
2323                                                 is_string( $innerAlias ) ? $innerAlias : $innerTable
2324                                         );
2325                                 }
2326                         } else {
2327                                 $joinedTable = $this->tableNameWithAlias( $table, $alias );
2328                         }
2329
2330                         // Is there a JOIN clause for this table?
2331                         if ( isset( $join_conds[$alias] ) ) {
2332                                 list( $joinType, $conds ) = $join_conds[$alias];
2333                                 $tableClause = $joinType;
2334                                 $tableClause .= ' ' . $joinedTable;
2335                                 if ( isset( $use_index[$alias] ) ) { // has USE INDEX?
2336                                         $use = $this->useIndexClause( implode( ',', (array)$use_index[$alias] ) );
2337                                         if ( $use != '' ) {
2338                                                 $tableClause .= ' ' . $use;
2339                                         }
2340                                 }
2341                                 if ( isset( $ignore_index[$alias] ) ) { // has IGNORE INDEX?
2342                                         $ignore = $this->ignoreIndexClause(
2343                                                 implode( ',', (array)$ignore_index[$alias] ) );
2344                                         if ( $ignore != '' ) {
2345                                                 $tableClause .= ' ' . $ignore;
2346                                         }
2347                                 }
2348                                 $on = $this->makeList( (array)$conds, self::LIST_AND );
2349                                 if ( $on != '' ) {
2350                                         $tableClause .= ' ON (' . $on . ')';
2351                                 }
2352
2353                                 $retJOIN[] = $tableClause;
2354                         } elseif ( isset( $use_index[$alias] ) ) {
2355                                 // Is there an INDEX clause for this table?
2356                                 $tableClause = $joinedTable;
2357                                 $tableClause .= ' ' . $this->useIndexClause(
2358                                                 implode( ',', (array)$use_index[$alias] )
2359                                         );
2360
2361                                 $ret[] = $tableClause;
2362                         } elseif ( isset( $ignore_index[$alias] ) ) {
2363                                 // Is there an INDEX clause for this table?
2364                                 $tableClause = $joinedTable;
2365                                 $tableClause .= ' ' . $this->ignoreIndexClause(
2366                                                 implode( ',', (array)$ignore_index[$alias] )
2367                                         );
2368
2369                                 $ret[] = $tableClause;
2370                         } else {
2371                                 $tableClause = $joinedTable;
2372
2373                                 $ret[] = $tableClause;
2374                         }
2375                 }
2376
2377                 // We can't separate explicit JOIN clauses with ',', use ' ' for those
2378                 $implicitJoins = $ret ? implode( ',', $ret ) : "";
2379                 $explicitJoins = $retJOIN ? implode( ' ', $retJOIN ) : "";
2380
2381                 // Compile our final table clause
2382                 return implode( ' ', [ $implicitJoins, $explicitJoins ] );
2383         }
2384
2385         /**
2386          * Allows for index remapping in queries where this is not consistent across DBMS
2387          *
2388          * @param string $index
2389          * @return string
2390          */
2391         protected function indexName( $index ) {
2392                 return isset( $this->indexAliases[$index] )
2393                         ? $this->indexAliases[$index]
2394                         : $index;
2395         }
2396
2397         public function addQuotes( $s ) {
2398                 if ( $s instanceof Blob ) {
2399                         $s = $s->fetch();
2400                 }
2401                 if ( $s === null ) {
2402                         return 'NULL';
2403                 } elseif ( is_bool( $s ) ) {
2404                         return (int)$s;
2405                 } else {
2406                         # This will also quote numeric values. This should be harmless,
2407                         # and protects against weird problems that occur when they really
2408                         # _are_ strings such as article titles and string->number->string
2409                         # conversion is not 1:1.
2410                         return "'" . $this->strencode( $s ) . "'";
2411                 }
2412         }
2413
2414         /**
2415          * Quotes an identifier using `backticks` or "double quotes" depending on the database type.
2416          * MySQL uses `backticks` while basically everything else uses double quotes.
2417          * Since MySQL is the odd one out here the double quotes are our generic
2418          * and we implement backticks in DatabaseMysqlBase.
2419          *
2420          * @param string $s
2421          * @return string
2422          */
2423         public function addIdentifierQuotes( $s ) {
2424                 return '"' . str_replace( '"', '""', $s ) . '"';
2425         }
2426
2427         /**
2428          * Returns if the given identifier looks quoted or not according to
2429          * the database convention for quoting identifiers .
2430          *
2431          * @note Do not use this to determine if untrusted input is safe.
2432          *   A malicious user can trick this function.
2433          * @param string $name
2434          * @return bool
2435          */
2436         public function isQuotedIdentifier( $name ) {
2437                 return $name[0] == '"' && substr( $name, -1, 1 ) == '"';
2438         }
2439
2440         /**
2441          * @param string $s
2442          * @param string $escapeChar
2443          * @return string
2444          */
2445         protected function escapeLikeInternal( $s, $escapeChar = '`' ) {
2446                 return str_replace( [ $escapeChar, '%', '_' ],
2447                         [ "{$escapeChar}{$escapeChar}", "{$escapeChar}%", "{$escapeChar}_" ],
2448                         $s );
2449         }
2450
2451         public function buildLike() {
2452                 $params = func_get_args();
2453
2454                 if ( count( $params ) > 0 && is_array( $params[0] ) ) {
2455                         $params = $params[0];
2456                 }
2457
2458                 $s = '';
2459
2460                 // We use ` instead of \ as the default LIKE escape character, since addQuotes()
2461                 // may escape backslashes, creating problems of double escaping. The `
2462                 // character has good cross-DBMS compatibility, avoiding special operators
2463                 // in MS SQL like ^ and %
2464                 $escapeChar = '`';
2465
2466                 foreach ( $params as $value ) {
2467                         if ( $value instanceof LikeMatch ) {
2468                                 $s .= $value->toString();
2469                         } else {
2470                                 $s .= $this->escapeLikeInternal( $value, $escapeChar );
2471                         }
2472                 }
2473
2474                 return ' LIKE ' .
2475                         $this->addQuotes( $s ) . ' ESCAPE ' . $this->addQuotes( $escapeChar ) . ' ';
2476         }
2477
2478         public function anyChar() {
2479                 return new LikeMatch( '_' );
2480         }
2481
2482         public function anyString() {
2483                 return new LikeMatch( '%' );
2484         }
2485
2486         public function nextSequenceValue( $seqName ) {
2487                 return null;
2488         }
2489
2490         /**
2491          * USE INDEX clause. Unlikely to be useful for anything but MySQL. This
2492          * is only needed because a) MySQL must be as efficient as possible due to
2493          * its use on Wikipedia, and b) MySQL 4.0 is kind of dumb sometimes about
2494          * which index to pick. Anyway, other databases might have different
2495          * indexes on a given table. So don't bother overriding this unless you're
2496          * MySQL.
2497          * @param string $index
2498          * @return string
2499          */
2500         public function useIndexClause( $index ) {
2501                 return '';
2502         }
2503
2504         /**
2505          * IGNORE INDEX clause. Unlikely to be useful for anything but MySQL. This
2506          * is only needed because a) MySQL must be as efficient as possible due to
2507          * its use on Wikipedia, and b) MySQL 4.0 is kind of dumb sometimes about
2508          * which index to pick. Anyway, other databases might have different
2509          * indexes on a given table. So don't bother overriding this unless you're
2510          * MySQL.
2511          * @param string $index
2512          * @return string
2513          */
2514         public function ignoreIndexClause( $index ) {
2515                 return '';
2516         }
2517
2518         public function replace( $table, $uniqueIndexes, $rows, $fname = __METHOD__ ) {
2519                 if ( count( $rows ) == 0 ) {
2520                         return;
2521                 }
2522
2523                 // Single row case
2524                 if ( !is_array( reset( $rows ) ) ) {
2525                         $rows = [ $rows ];
2526                 }
2527
2528                 try {
2529                         $this->startAtomic( $fname, self::ATOMIC_CANCELABLE );
2530                         $affectedRowCount = 0;
2531                         foreach ( $rows as $row ) {
2532                                 // Delete rows which collide with this one
2533                                 $indexWhereClauses = [];
2534                                 foreach ( $uniqueIndexes as $index ) {
2535                                         $indexColumns = (array)$index;
2536                                         $indexRowValues = array_intersect_key( $row, array_flip( $indexColumns ) );
2537                                         if ( count( $indexRowValues ) != count( $indexColumns ) ) {
2538                                                 throw new DBUnexpectedError(
2539                                                         $this,
2540                                                         'New record does not provide all values for unique key (' .
2541                                                         implode( ', ', $indexColumns ) . ')'
2542                                                 );
2543                                         } elseif ( in_array( null, $indexRowValues, true ) ) {
2544                                                 throw new DBUnexpectedError(
2545                                                         $this,
2546                                                         'New record has a null value for unique key (' .
2547                                                         implode( ', ', $indexColumns ) . ')'
2548                                                 );
2549                                         }
2550                                         $indexWhereClauses[] = $this->makeList( $indexRowValues, LIST_AND );
2551                                 }
2552
2553                                 if ( $indexWhereClauses ) {
2554                                         $this->delete( $table, $this->makeList( $indexWhereClauses, LIST_OR ), $fname );
2555                                         $affectedRowCount += $this->affectedRows();
2556                                 }
2557
2558                                 // Now insert the row
2559                                 $this->insert( $table, $row, $fname );
2560                                 $affectedRowCount += $this->affectedRows();
2561                         }
2562                         $this->endAtomic( $fname );
2563                         $this->affectedRowCount = $affectedRowCount;
2564                 } catch ( Exception $e ) {
2565                         $this->cancelAtomic( $fname );
2566                         throw $e;
2567                 }
2568         }
2569
2570         /**
2571          * REPLACE query wrapper for MySQL and SQLite, which have a native REPLACE
2572          * statement.
2573          *
2574          * @param string $table Table name
2575          * @param array|string $rows Row(s) to insert
2576          * @param string $fname Caller function name
2577          *
2578          * @return ResultWrapper
2579          */
2580         protected function nativeReplace( $table, $rows, $fname ) {
2581                 $table = $this->tableName( $table );
2582
2583                 # Single row case
2584                 if ( !is_array( reset( $rows ) ) ) {
2585                         $rows = [ $rows ];
2586                 }
2587
2588                 $sql = "REPLACE INTO $table (" . implode( ',', array_keys( $rows[0] ) ) . ') VALUES ';
2589                 $first = true;
2590
2591                 foreach ( $rows as $row ) {
2592                         if ( $first ) {
2593                                 $first = false;
2594                         } else {
2595                                 $sql .= ',';
2596                         }
2597
2598                         $sql .= '(' . $this->makeList( $row ) . ')';
2599                 }
2600
2601                 return $this->query( $sql, $fname );
2602         }
2603
2604         public function upsert( $table, array $rows, array $uniqueIndexes, array $set,
2605                 $fname = __METHOD__
2606         ) {
2607                 if ( !count( $rows ) ) {
2608                         return true; // nothing to do
2609                 }
2610
2611                 if ( !is_array( reset( $rows ) ) ) {
2612                         $rows = [ $rows ];
2613                 }
2614
2615                 if ( count( $uniqueIndexes ) ) {
2616                         $clauses = []; // list WHERE clauses that each identify a single row
2617                         foreach ( $rows as $row ) {
2618                                 foreach ( $uniqueIndexes as $index ) {
2619                                         $index = is_array( $index ) ? $index : [ $index ]; // columns
2620                                         $rowKey = []; // unique key to this row
2621                                         foreach ( $index as $column ) {
2622                                                 $rowKey[$column] = $row[$column];
2623                                         }
2624                                         $clauses[] = $this->makeList( $rowKey, self::LIST_AND );
2625                                 }
2626                         }
2627                         $where = [ $this->makeList( $clauses, self::LIST_OR ) ];
2628                 } else {
2629                         $where = false;
2630                 }
2631
2632                 $affectedRowCount = 0;
2633                 try {
2634                         $this->startAtomic( $fname, self::ATOMIC_CANCELABLE );
2635                         # Update any existing conflicting row(s)
2636                         if ( $where !== false ) {
2637                                 $ok = $this->update( $table, $set, $where, $fname );
2638                                 $affectedRowCount += $this->affectedRows();
2639                         } else {
2640                                 $ok = true;
2641                         }
2642                         # Now insert any non-conflicting row(s)
2643                         $ok = $this->insert( $table, $rows, $fname, [ 'IGNORE' ] ) && $ok;
2644                         $affectedRowCount += $this->affectedRows();
2645                         $this->endAtomic( $fname );
2646                         $this->affectedRowCount = $affectedRowCount;
2647                 } catch ( Exception $e ) {
2648                         $this->cancelAtomic( $fname );
2649                         throw $e;
2650                 }
2651
2652                 return $ok;
2653         }
2654
2655         public function deleteJoin( $delTable, $joinTable, $delVar, $joinVar, $conds,
2656                 $fname = __METHOD__
2657         ) {
2658                 if ( !$conds ) {
2659                         throw new DBUnexpectedError( $this, __METHOD__ . ' called with empty $conds' );
2660                 }
2661
2662                 $delTable = $this->tableName( $delTable );
2663                 $joinTable = $this->tableName( $joinTable );
2664                 $sql = "DELETE FROM $delTable WHERE $delVar IN (SELECT $joinVar FROM $joinTable ";
2665                 if ( $conds != '*' ) {
2666                         $sql .= 'WHERE ' . $this->makeList( $conds, self::LIST_AND );
2667                 }
2668                 $sql .= ')';
2669
2670                 $this->query( $sql, $fname );
2671         }
2672
2673         public function textFieldSize( $table, $field ) {
2674                 $table = $this->tableName( $table );
2675                 $sql = "SHOW COLUMNS FROM $table LIKE \"$field\";";
2676                 $res = $this->query( $sql, __METHOD__ );
2677                 $row = $this->fetchObject( $res );
2678
2679                 $m = [];
2680
2681                 if ( preg_match( '/\((.*)\)/', $row->Type, $m ) ) {
2682                         $size = $m[1];
2683                 } else {
2684                         $size = -1;
2685                 }
2686
2687                 return $size;
2688         }
2689
2690         public function delete( $table, $conds, $fname = __METHOD__ ) {
2691                 if ( !$conds ) {
2692                         throw new DBUnexpectedError( $this, __METHOD__ . ' called with no conditions' );
2693                 }
2694
2695                 $table = $this->tableName( $table );
2696                 $sql = "DELETE FROM $table";
2697
2698                 if ( $conds != '*' ) {
2699                         if ( is_array( $conds ) ) {
2700                                 $conds = $this->makeList( $conds, self::LIST_AND );
2701                         }
2702                         $sql .= ' WHERE ' . $conds;
2703                 }
2704
2705                 return $this->query( $sql, $fname );
2706         }
2707
2708         final public function insertSelect(
2709                 $destTable, $srcTable, $varMap, $conds,
2710                 $fname = __METHOD__, $insertOptions = [], $selectOptions = [], $selectJoinConds = []
2711         ) {
2712                 static $hints = [ 'NO_AUTO_COLUMNS' ];
2713
2714                 $insertOptions = (array)$insertOptions;
2715                 $selectOptions = (array)$selectOptions;
2716
2717                 if ( $this->cliMode && $this->isInsertSelectSafe( $insertOptions, $selectOptions ) ) {
2718                         // For massive migrations with downtime, we don't want to select everything
2719                         // into memory and OOM, so do all this native on the server side if possible.
2720                         return $this->nativeInsertSelect(
2721                                 $destTable,
2722                                 $srcTable,
2723                                 $varMap,
2724                                 $conds,
2725                                 $fname,
2726                                 array_diff( $insertOptions, $hints ),
2727                                 $selectOptions,
2728                                 $selectJoinConds
2729                         );
2730                 }
2731
2732                 return $this->nonNativeInsertSelect(
2733                         $destTable,
2734                         $srcTable,
2735                         $varMap,
2736                         $conds,
2737                         $fname,
2738                         array_diff( $insertOptions, $hints ),
2739                         $selectOptions,
2740                         $selectJoinConds
2741                 );
2742         }
2743
2744         /**
2745          * @param array $insertOptions INSERT options
2746          * @param array $selectOptions SELECT options
2747          * @return bool Whether an INSERT SELECT with these options will be replication safe
2748          * @since 1.31
2749          */
2750         protected function isInsertSelectSafe( array $insertOptions, array $selectOptions ) {
2751                 return true;
2752         }
2753
2754         /**
2755          * Implementation of insertSelect() based on select() and insert()
2756          *
2757          * @see IDatabase::insertSelect()
2758          * @since 1.30
2759          * @param string $destTable
2760          * @param string|array $srcTable
2761          * @param array $varMap
2762          * @param array $conds
2763          * @param string $fname
2764          * @param array $insertOptions
2765          * @param array $selectOptions
2766          * @param array $selectJoinConds
2767          * @return bool
2768          */
2769         protected function nonNativeInsertSelect( $destTable, $srcTable, $varMap, $conds,
2770                 $fname = __METHOD__,
2771                 $insertOptions = [], $selectOptions = [], $selectJoinConds = []
2772         ) {
2773                 // For web requests, do a locking SELECT and then INSERT. This puts the SELECT burden
2774                 // on only the master (without needing row-based-replication). It also makes it easy to
2775                 // know how big the INSERT is going to be.
2776                 $fields = [];
2777                 foreach ( $varMap as $dstColumn => $sourceColumnOrSql ) {
2778                         $fields[] = $this->fieldNameWithAlias( $sourceColumnOrSql, $dstColumn );
2779                 }
2780                 $selectOptions[] = 'FOR UPDATE';
2781                 $res = $this->select(
2782                         $srcTable, implode( ',', $fields ), $conds, $fname, $selectOptions, $selectJoinConds
2783                 );
2784                 if ( !$res ) {
2785                         return false;
2786                 }
2787
2788                 try {
2789                         $affectedRowCount = 0;
2790                         $this->startAtomic( $fname, self::ATOMIC_CANCELABLE );
2791                         $rows = [];
2792                         $ok = true;
2793                         foreach ( $res as $row ) {
2794                                 $rows[] = (array)$row;
2795
2796                                 // Avoid inserts that are too huge
2797                                 if ( count( $rows ) >= $this->nonNativeInsertSelectBatchSize ) {
2798                                         $ok = $this->insert( $destTable, $rows, $fname, $insertOptions );
2799                                         if ( !$ok ) {
2800                                                 break;
2801                                         }
2802                                         $affectedRowCount += $this->affectedRows();
2803                                         $rows = [];
2804                                 }
2805                         }
2806                         if ( $rows && $ok ) {
2807                                 $ok = $this->insert( $destTable, $rows, $fname, $insertOptions );
2808                                 if ( $ok ) {
2809                                         $affectedRowCount += $this->affectedRows();
2810                                 }
2811                         }
2812                         if ( $ok ) {
2813                                 $this->endAtomic( $fname );
2814                                 $this->affectedRowCount = $affectedRowCount;
2815                         } else {
2816                                 $this->cancelAtomic( $fname );
2817                         }
2818                         return $ok;
2819                 } catch ( Exception $e ) {
2820                         $this->cancelAtomic( $fname );
2821                         throw $e;
2822                 }
2823         }
2824
2825         /**
2826          * Native server-side implementation of insertSelect() for situations where
2827          * we don't want to select everything into memory
2828          *
2829          * @see IDatabase::insertSelect()
2830          * @param string $destTable
2831          * @param string|array $srcTable
2832          * @param array $varMap
2833          * @param array $conds
2834          * @param string $fname
2835          * @param array $insertOptions
2836          * @param array $selectOptions
2837          * @param array $selectJoinConds
2838          * @return bool
2839          */
2840         protected function nativeInsertSelect( $destTable, $srcTable, $varMap, $conds,
2841                 $fname = __METHOD__,
2842                 $insertOptions = [], $selectOptions = [], $selectJoinConds = []
2843         ) {
2844                 $destTable = $this->tableName( $destTable );
2845
2846                 if ( !is_array( $insertOptions ) ) {
2847                         $insertOptions = [ $insertOptions ];
2848                 }
2849
2850                 $insertOptions = $this->makeInsertOptions( $insertOptions );
2851
2852                 $selectSql = $this->selectSQLText(
2853                         $srcTable,
2854                         array_values( $varMap ),
2855                         $conds,
2856                         $fname,
2857                         $selectOptions,
2858                         $selectJoinConds
2859                 );
2860
2861                 $sql = "INSERT $insertOptions" .
2862                         " INTO $destTable (" . implode( ',', array_keys( $varMap ) ) . ') ' .
2863                         $selectSql;
2864
2865                 return $this->query( $sql, $fname );
2866         }
2867
2868         /**
2869          * Construct a LIMIT query with optional offset. This is used for query
2870          * pages. The SQL should be adjusted so that only the first $limit rows
2871          * are returned. If $offset is provided as well, then the first $offset
2872          * rows should be discarded, and the next $limit rows should be returned.
2873          * If the result of the query is not ordered, then the rows to be returned
2874          * are theoretically arbitrary.
2875          *
2876          * $sql is expected to be a SELECT, if that makes a difference.
2877          *
2878          * The version provided by default works in MySQL and SQLite. It will very
2879          * likely need to be overridden for most other DBMSes.
2880          *
2881          * @param string $sql SQL query we will append the limit too
2882          * @param int $limit The SQL limit
2883          * @param int|bool $offset The SQL offset (default false)
2884          * @throws DBUnexpectedError
2885          * @return string
2886          */
2887         public function limitResult( $sql, $limit, $offset = false ) {
2888                 if ( !is_numeric( $limit ) ) {
2889                         throw new DBUnexpectedError( $this,
2890                                 "Invalid non-numeric limit passed to limitResult()\n" );
2891                 }
2892
2893                 return "$sql LIMIT "
2894                 . ( ( is_numeric( $offset ) && $offset != 0 ) ? "{$offset}," : "" )
2895                 . "{$limit} ";
2896         }
2897
2898         public function unionSupportsOrderAndLimit() {
2899                 return true; // True for almost every DB supported
2900         }
2901
2902         public function unionQueries( $sqls, $all ) {
2903                 $glue = $all ? ') UNION ALL (' : ') UNION (';
2904
2905                 return '(' . implode( $glue, $sqls ) . ')';
2906         }
2907
2908         public function unionConditionPermutations(
2909                 $table, $vars, array $permute_conds, $extra_conds = '', $fname = __METHOD__,
2910                 $options = [], $join_conds = []
2911         ) {
2912                 // First, build the Cartesian product of $permute_conds
2913                 $conds = [ [] ];
2914                 foreach ( $permute_conds as $field => $values ) {
2915                         if ( !$values ) {
2916                                 // Skip empty $values
2917                                 continue;
2918                         }
2919                         $values = array_unique( $values ); // For sanity
2920                         $newConds = [];
2921                         foreach ( $conds as $cond ) {
2922                                 foreach ( $values as $value ) {
2923                                         $cond[$field] = $value;
2924                                         $newConds[] = $cond; // Arrays are by-value, not by-reference, so this works
2925                                 }
2926                         }
2927                         $conds = $newConds;
2928                 }
2929
2930                 $extra_conds = $extra_conds === '' ? [] : (array)$extra_conds;
2931
2932                 // If there's just one condition and no subordering, hand off to
2933                 // selectSQLText directly.
2934                 if ( count( $conds ) === 1 &&
2935                         ( !isset( $options['INNER ORDER BY'] ) || !$this->unionSupportsOrderAndLimit() )
2936                 ) {
2937                         return $this->selectSQLText(
2938                                 $table, $vars, $conds[0] + $extra_conds, $fname, $options, $join_conds
2939                         );
2940                 }
2941
2942                 // Otherwise, we need to pull out the order and limit to apply after
2943                 // the union. Then build the SQL queries for each set of conditions in
2944                 // $conds. Then union them together (using UNION ALL, because the
2945                 // product *should* already be distinct).
2946                 $orderBy = $this->makeOrderBy( $options );
2947                 $limit = isset( $options['LIMIT'] ) ? $options['LIMIT'] : null;
2948                 $offset = isset( $options['OFFSET'] ) ? $options['OFFSET'] : false;
2949                 $all = empty( $options['NOTALL'] ) && !in_array( 'NOTALL', $options );
2950                 if ( !$this->unionSupportsOrderAndLimit() ) {
2951                         unset( $options['ORDER BY'], $options['LIMIT'], $options['OFFSET'] );
2952                 } else {
2953                         if ( array_key_exists( 'INNER ORDER BY', $options ) ) {
2954                                 $options['ORDER BY'] = $options['INNER ORDER BY'];
2955                         }
2956                         if ( $limit !== null && is_numeric( $offset ) && $offset != 0 ) {
2957                                 // We need to increase the limit by the offset rather than
2958                                 // using the offset directly, otherwise it'll skip incorrectly
2959                                 // in the subqueries.
2960                                 $options['LIMIT'] = $limit + $offset;
2961                                 unset( $options['OFFSET'] );
2962                         }
2963                 }
2964
2965                 $sqls = [];
2966                 foreach ( $conds as $cond ) {
2967                         $sqls[] = $this->selectSQLText(
2968                                 $table, $vars, $cond + $extra_conds, $fname, $options, $join_conds
2969                         );
2970                 }
2971                 $sql = $this->unionQueries( $sqls, $all ) . $orderBy;
2972                 if ( $limit !== null ) {
2973                         $sql = $this->limitResult( $sql, $limit, $offset );
2974                 }
2975
2976                 return $sql;
2977         }
2978
2979         public function conditional( $cond, $trueVal, $falseVal ) {
2980                 if ( is_array( $cond ) ) {
2981                         $cond = $this->makeList( $cond, self::LIST_AND );
2982                 }
2983
2984                 return " (CASE WHEN $cond THEN $trueVal ELSE $falseVal END) ";
2985         }
2986
2987         public function strreplace( $orig, $old, $new ) {
2988                 return "REPLACE({$orig}, {$old}, {$new})";
2989         }
2990
2991         public function getServerUptime() {
2992                 return 0;
2993         }
2994
2995         public function wasDeadlock() {
2996                 return false;
2997         }
2998
2999         public function wasLockTimeout() {
3000                 return false;
3001         }
3002
3003         public function wasConnectionLoss() {
3004                 return $this->wasConnectionError( $this->lastErrno() );
3005         }
3006
3007         public function wasReadOnlyError() {
3008                 return false;
3009         }
3010
3011         public function wasErrorReissuable() {
3012                 return (
3013                         $this->wasDeadlock() ||
3014                         $this->wasLockTimeout() ||
3015                         $this->wasConnectionLoss()
3016                 );
3017         }
3018
3019         /**
3020          * Do not use this method outside of Database/DBError classes
3021          *
3022          * @param int|string $errno
3023          * @return bool Whether the given query error was a connection drop
3024          */
3025         public function wasConnectionError( $errno ) {
3026                 return false;
3027         }
3028
3029         public function deadlockLoop() {
3030                 $args = func_get_args();
3031                 $function = array_shift( $args );
3032                 $tries = self::DEADLOCK_TRIES;
3033
3034                 $this->begin( __METHOD__ );
3035
3036                 $retVal = null;
3037                 /** @var Exception $e */
3038                 $e = null;
3039                 do {
3040                         try {
3041                                 $retVal = call_user_func_array( $function, $args );
3042                                 break;
3043                         } catch ( DBQueryError $e ) {
3044                                 if ( $this->wasDeadlock() ) {
3045                                         // Retry after a randomized delay
3046                                         usleep( mt_rand( self::DEADLOCK_DELAY_MIN, self::DEADLOCK_DELAY_MAX ) );
3047                                 } else {
3048                                         // Throw the error back up
3049                                         throw $e;
3050                                 }
3051                         }
3052                 } while ( --$tries > 0 );
3053
3054                 if ( $tries <= 0 ) {
3055                         // Too many deadlocks; give up
3056                         $this->rollback( __METHOD__ );
3057                         throw $e;
3058                 } else {
3059                         $this->commit( __METHOD__ );
3060
3061                         return $retVal;
3062                 }
3063         }
3064
3065         public function masterPosWait( DBMasterPos $pos, $timeout ) {
3066                 # Real waits are implemented in the subclass.
3067                 return 0;
3068         }
3069
3070         public function getReplicaPos() {
3071                 # Stub
3072                 return false;
3073         }
3074
3075         public function getMasterPos() {
3076                 # Stub
3077                 return false;
3078         }
3079
3080         public function serverIsReadOnly() {
3081                 return false;
3082         }
3083
3084         final public function onTransactionResolution( callable $callback, $fname = __METHOD__ ) {
3085                 if ( !$this->trxLevel ) {
3086                         throw new DBUnexpectedError( $this, "No transaction is active." );
3087                 }
3088                 $this->trxEndCallbacks[] = [ $callback, $fname ];
3089         }
3090
3091         final public function onTransactionIdle( callable $callback, $fname = __METHOD__ ) {
3092                 if ( !$this->trxLevel && $this->getTransactionRoundId() ) {
3093                         // Start an implicit transaction similar to how query() does
3094                         $this->begin( __METHOD__, self::TRANSACTION_INTERNAL );
3095                         $this->trxAutomatic = true;
3096                 }
3097
3098                 $this->trxIdleCallbacks[] = [ $callback, $fname ];
3099                 if ( !$this->trxLevel ) {
3100                         $this->runOnTransactionIdleCallbacks( self::TRIGGER_IDLE );
3101                 }
3102         }
3103
3104         final public function onTransactionPreCommitOrIdle( callable $callback, $fname = __METHOD__ ) {
3105                 if ( !$this->trxLevel && $this->getTransactionRoundId() ) {
3106                         // Start an implicit transaction similar to how query() does
3107                         $this->begin( __METHOD__, self::TRANSACTION_INTERNAL );
3108                         $this->trxAutomatic = true;
3109                 }
3110
3111                 if ( $this->trxLevel ) {
3112                         $this->trxPreCommitCallbacks[] = [ $callback, $fname ];
3113                 } else {
3114                         // No transaction is active nor will start implicitly, so make one for this callback
3115                         $this->startAtomic( __METHOD__, self::ATOMIC_CANCELABLE );
3116                         try {
3117                                 call_user_func( $callback );
3118                                 $this->endAtomic( __METHOD__ );
3119                         } catch ( Exception $e ) {
3120                                 $this->cancelAtomic( __METHOD__ );
3121                                 throw $e;
3122                         }
3123                 }
3124         }
3125
3126         final public function setTransactionListener( $name, callable $callback = null ) {
3127                 if ( $callback ) {
3128                         $this->trxRecurringCallbacks[$name] = $callback;
3129                 } else {
3130                         unset( $this->trxRecurringCallbacks[$name] );
3131                 }
3132         }
3133
3134         /**
3135          * Whether to disable running of post-COMMIT/ROLLBACK callbacks
3136          *
3137          * This method should not be used outside of Database/LoadBalancer
3138          *
3139          * @param bool $suppress
3140          * @since 1.28
3141          */
3142         final public function setTrxEndCallbackSuppression( $suppress ) {
3143                 $this->trxEndCallbacksSuppressed = $suppress;
3144         }
3145
3146         /**
3147          * Actually run and consume any "on transaction idle/resolution" callbacks.
3148          *
3149          * This method should not be used outside of Database/LoadBalancer
3150          *
3151          * @param int $trigger IDatabase::TRIGGER_* constant
3152          * @since 1.20
3153          * @throws Exception
3154          */
3155         public function runOnTransactionIdleCallbacks( $trigger ) {
3156                 if ( $this->trxEndCallbacksSuppressed ) {
3157                         return;
3158                 }
3159
3160                 $autoTrx = $this->getFlag( self::DBO_TRX ); // automatic begin() enabled?
3161                 /** @var Exception $e */
3162                 $e = null; // first exception
3163                 do { // callbacks may add callbacks :)
3164                         $callbacks = array_merge(
3165                                 $this->trxIdleCallbacks,
3166                                 $this->trxEndCallbacks // include "transaction resolution" callbacks
3167                         );
3168                         $this->trxIdleCallbacks = []; // consumed (and recursion guard)
3169                         $this->trxEndCallbacks = []; // consumed (recursion guard)
3170                         foreach ( $callbacks as $callback ) {
3171                                 try {
3172                                         list( $phpCallback ) = $callback;
3173                                         $this->clearFlag( self::DBO_TRX ); // make each query its own transaction
3174                                         call_user_func_array( $phpCallback, [ $trigger ] );
3175                                         if ( $autoTrx ) {
3176                                                 $this->setFlag( self::DBO_TRX ); // restore automatic begin()
3177                                         } else {
3178                                                 $this->clearFlag( self::DBO_TRX ); // restore auto-commit
3179                                         }
3180                                 } catch ( Exception $ex ) {
3181                                         call_user_func( $this->errorLogger, $ex );
3182                                         $e = $e ?: $ex;
3183                                         // Some callbacks may use startAtomic/endAtomic, so make sure
3184                                         // their transactions are ended so other callbacks don't fail
3185                                         if ( $this->trxLevel() ) {
3186                                                 $this->rollback( __METHOD__, self::FLUSHING_INTERNAL );
3187                                         }
3188                                 }
3189                         }
3190                 } while ( count( $this->trxIdleCallbacks ) );
3191
3192                 if ( $e instanceof Exception ) {
3193                         throw $e; // re-throw any first exception
3194                 }
3195         }
3196
3197         /**
3198          * Actually run and consume any "on transaction pre-commit" callbacks.
3199          *
3200          * This method should not be used outside of Database/LoadBalancer
3201          *
3202          * @since 1.22
3203          * @throws Exception
3204          */
3205         public function runOnTransactionPreCommitCallbacks() {
3206                 $e = null; // first exception
3207                 do { // callbacks may add callbacks :)
3208                         $callbacks = $this->trxPreCommitCallbacks;
3209                         $this->trxPreCommitCallbacks = []; // consumed (and recursion guard)
3210                         foreach ( $callbacks as $callback ) {
3211                                 try {
3212                                         list( $phpCallback ) = $callback;
3213                                         call_user_func( $phpCallback );
3214                                 } catch ( Exception $ex ) {
3215                                         call_user_func( $this->errorLogger, $ex );
3216                                         $e = $e ?: $ex;
3217                                 }
3218                         }
3219                 } while ( count( $this->trxPreCommitCallbacks ) );
3220
3221                 if ( $e instanceof Exception ) {
3222                         throw $e; // re-throw any first exception
3223                 }
3224         }
3225
3226         /**
3227          * Actually run any "transaction listener" callbacks.
3228          *
3229          * This method should not be used outside of Database/LoadBalancer
3230          *
3231          * @param int $trigger IDatabase::TRIGGER_* constant
3232          * @throws Exception
3233          * @since 1.20
3234          */
3235         public function runTransactionListenerCallbacks( $trigger ) {
3236                 if ( $this->trxEndCallbacksSuppressed ) {
3237                         return;
3238                 }
3239
3240                 /** @var Exception $e */
3241                 $e = null; // first exception
3242
3243                 foreach ( $this->trxRecurringCallbacks as $phpCallback ) {
3244                         try {
3245                                 $phpCallback( $trigger, $this );
3246                         } catch ( Exception $ex ) {
3247                                 call_user_func( $this->errorLogger, $ex );
3248                                 $e = $e ?: $ex;
3249                         }
3250                 }
3251
3252                 if ( $e instanceof Exception ) {
3253                         throw $e; // re-throw any first exception
3254                 }
3255         }
3256
3257         /**
3258          * Create a savepoint
3259          *
3260          * This is used internally to implement atomic sections. It should not be
3261          * used otherwise.
3262          *
3263          * @since 1.31
3264          * @param string $identifier Identifier for the savepoint
3265          * @param string $fname Calling function name
3266          */
3267         protected function doSavepoint( $identifier, $fname ) {
3268                 $this->query( 'SAVEPOINT ' . $this->addIdentifierQuotes( $identifier ), $fname );
3269         }
3270
3271         /**
3272          * Release a savepoint
3273          *
3274          * This is used internally to implement atomic sections. It should not be
3275          * used otherwise.
3276          *
3277          * @since 1.31
3278          * @param string $identifier Identifier for the savepoint
3279          * @param string $fname Calling function name
3280          */
3281         protected function doReleaseSavepoint( $identifier, $fname ) {
3282                 $this->query( 'RELEASE SAVEPOINT ' . $this->addIdentifierQuotes( $identifier ), $fname );
3283         }
3284
3285         /**
3286          * Rollback to a savepoint
3287          *
3288          * This is used internally to implement atomic sections. It should not be
3289          * used otherwise.
3290          *
3291          * @since 1.31
3292          * @param string $identifier Identifier for the savepoint
3293          * @param string $fname Calling function name
3294          */
3295         protected function doRollbackToSavepoint( $identifier, $fname ) {
3296                 $this->query( 'ROLLBACK TO SAVEPOINT ' . $this->addIdentifierQuotes( $identifier ), $fname );
3297         }
3298
3299         final public function startAtomic(
3300                 $fname = __METHOD__, $cancelable = self::ATOMIC_NOT_CANCELABLE
3301         ) {
3302                 $savepointId = $cancelable === self::ATOMIC_CANCELABLE ? 'n/a' : null;
3303                 if ( !$this->trxLevel ) {
3304                         $this->begin( $fname, self::TRANSACTION_INTERNAL );
3305                         // If DBO_TRX is set, a series of startAtomic/endAtomic pairs will result
3306                         // in all changes being in one transaction to keep requests transactional.
3307                         if ( !$this->getFlag( self::DBO_TRX ) ) {
3308                                 $this->trxAutomaticAtomic = true;
3309                         }
3310                 } elseif ( $cancelable === self::ATOMIC_CANCELABLE ) {
3311                         $savepointId = 'wikimedia_rdbms_atomic' . ++$this->trxAtomicCounter;
3312                         if ( strlen( $savepointId ) > 30 ) { // 30 == Oracle's identifier length limit (pre 12c)
3313                                 $this->queryLogger->warning(
3314                                         'There have been an excessively large number of atomic sections in a transaction'
3315                                         . " started by $this->trxFname, reusing IDs (at $fname)",
3316                                         [ 'trace' => ( new RuntimeException() )->getTraceAsString() ]
3317                                 );
3318                                 $this->trxAtomicCounter = 0;
3319                                 $savepointId = 'wikimedia_rdbms_atomic' . ++$this->trxAtomicCounter;
3320                         }
3321                         $this->doSavepoint( $savepointId, $fname );
3322                 }
3323
3324                 $this->trxAtomicLevels[] = [ $fname, $savepointId ];
3325         }
3326
3327         final public function endAtomic( $fname = __METHOD__ ) {
3328                 if ( !$this->trxLevel ) {
3329                         throw new DBUnexpectedError( $this, "No atomic transaction is open (got $fname)." );
3330                 }
3331
3332                 list( $savedFname, $savepointId ) = $this->trxAtomicLevels
3333                         ? array_pop( $this->trxAtomicLevels ) : [ null, null ];
3334                 if ( $savedFname !== $fname ) {
3335                         throw new DBUnexpectedError( $this, "Invalid atomic section ended (got $fname)." );
3336                 }
3337
3338                 if ( !$this->trxAtomicLevels && $this->trxAutomaticAtomic ) {
3339                         $this->commit( $fname, self::FLUSHING_INTERNAL );
3340                 } elseif ( $savepointId && $savepointId !== 'n/a' ) {
3341                         $this->doReleaseSavepoint( $savepointId, $fname );
3342                 }
3343         }
3344
3345         final public function cancelAtomic( $fname = __METHOD__ ) {
3346                 if ( !$this->trxLevel ) {
3347                         throw new DBUnexpectedError( $this, "No atomic transaction is open (got $fname)." );
3348                 }
3349
3350                 list( $savedFname, $savepointId ) = $this->trxAtomicLevels
3351                         ? array_pop( $this->trxAtomicLevels ) : [ null, null ];
3352                 if ( $savedFname !== $fname ) {
3353                         throw new DBUnexpectedError( $this, "Invalid atomic section ended (got $fname)." );
3354                 }
3355                 if ( !$savepointId ) {
3356                         throw new DBUnexpectedError( $this, "Uncancelable atomic section canceled (got $fname)." );
3357                 }
3358
3359                 if ( !$this->trxAtomicLevels && $this->trxAutomaticAtomic ) {
3360                         $this->rollback( $fname, self::FLUSHING_INTERNAL );
3361                 } elseif ( $savepointId !== 'n/a' ) {
3362                         $this->doRollbackToSavepoint( $savepointId, $fname );
3363                 }
3364
3365                 $this->affectedRowCount = 0; // for the sake of consistency
3366         }
3367
3368         final public function doAtomicSection( $fname, callable $callback ) {
3369                 $this->startAtomic( $fname, self::ATOMIC_CANCELABLE );
3370                 try {
3371                         $res = call_user_func_array( $callback, [ $this, $fname ] );
3372                 } catch ( Exception $e ) {
3373                         $this->cancelAtomic( $fname );
3374                         throw $e;
3375                 }
3376                 $this->endAtomic( $fname );
3377
3378                 return $res;
3379         }
3380
3381         final public function begin( $fname = __METHOD__, $mode = self::TRANSACTION_EXPLICIT ) {
3382                 // Protect against mismatched atomic section, transaction nesting, and snapshot loss
3383                 if ( $this->trxLevel ) {
3384                         if ( $this->trxAtomicLevels ) {
3385                                 $levels = array_reduce( $this->trxAtomicLevels, function ( $accum, $v ) {
3386                                         return $accum === null ? $v[0] : "$accum, " . $v[0];
3387                                 } );
3388                                 $msg = "$fname: Got explicit BEGIN while atomic section(s) $levels are open.";
3389                                 throw new DBUnexpectedError( $this, $msg );
3390                         } elseif ( !$this->trxAutomatic ) {
3391                                 $msg = "$fname: Explicit transaction already active (from {$this->trxFname}).";
3392                                 throw new DBUnexpectedError( $this, $msg );
3393                         } else {
3394                                 $msg = "$fname: Implicit transaction already active (from {$this->trxFname}).";
3395                                 throw new DBUnexpectedError( $this, $msg );
3396                         }
3397                 } elseif ( $this->getFlag( self::DBO_TRX ) && $mode !== self::TRANSACTION_INTERNAL ) {
3398                         $msg = "$fname: Implicit transaction expected (DBO_TRX set).";
3399                         throw new DBUnexpectedError( $this, $msg );
3400                 }
3401
3402                 // Avoid fatals if close() was called
3403                 $this->assertOpen();
3404
3405                 $this->doBegin( $fname );
3406                 $this->trxAtomicCounter = 0;
3407                 $this->trxTimestamp = microtime( true );
3408                 $this->trxFname = $fname;
3409                 $this->trxDoneWrites = false;
3410                 $this->trxAutomaticAtomic = false;
3411                 $this->trxAtomicLevels = [];
3412                 $this->trxShortId = sprintf( '%06x', mt_rand( 0, 0xffffff ) );
3413                 $this->trxWriteDuration = 0.0;
3414                 $this->trxWriteQueryCount = 0;
3415                 $this->trxWriteAffectedRows = 0;
3416                 $this->trxWriteAdjDuration = 0.0;
3417                 $this->trxWriteAdjQueryCount = 0;
3418                 $this->trxWriteCallers = [];
3419                 // First SELECT after BEGIN will establish the snapshot in REPEATABLE-READ.
3420                 // Get an estimate of the replication lag before any such queries.
3421                 $this->trxReplicaLag = null; // clear cached value first
3422                 $this->trxReplicaLag = $this->getApproximateLagStatus()['lag'];
3423                 // T147697: make explicitTrxActive() return true until begin() finishes. This way, no
3424                 // caller will think its OK to muck around with the transaction just because startAtomic()
3425                 // has not yet completed (e.g. setting trxAtomicLevels).
3426                 $this->trxAutomatic = ( $mode === self::TRANSACTION_INTERNAL );
3427         }
3428
3429         /**
3430          * Issues the BEGIN command to the database server.
3431          *
3432          * @see Database::begin()
3433          * @param string $fname
3434          */
3435         protected function doBegin( $fname ) {
3436                 $this->query( 'BEGIN', $fname );
3437                 $this->trxLevel = 1;
3438         }
3439
3440         final public function commit( $fname = __METHOD__, $flush = '' ) {
3441                 if ( $this->trxLevel && $this->trxAtomicLevels ) {
3442                         // There are still atomic sections open. This cannot be ignored
3443                         $levels = array_reduce( $this->trxAtomicLevels, function ( $accum, $v ) {
3444                                 return $accum === null ? $v[0] : "$accum, " . $v[0];
3445                         } );
3446                         throw new DBUnexpectedError(
3447                                 $this,
3448                                 "$fname: Got COMMIT while atomic sections $levels are still open."
3449                         );
3450                 }
3451
3452                 if ( $flush === self::FLUSHING_INTERNAL || $flush === self::FLUSHING_ALL_PEERS ) {
3453                         if ( !$this->trxLevel ) {
3454                                 return; // nothing to do
3455                         } elseif ( !$this->trxAutomatic ) {
3456                                 throw new DBUnexpectedError(
3457                                         $this,
3458                                         "$fname: Flushing an explicit transaction, getting out of sync."
3459                                 );
3460                         }
3461                 } else {
3462                         if ( !$this->trxLevel ) {
3463                                 $this->queryLogger->error(
3464                                         "$fname: No transaction to commit, something got out of sync." );
3465                                 return; // nothing to do
3466                         } elseif ( $this->trxAutomatic ) {
3467                                 throw new DBUnexpectedError(
3468                                         $this,
3469                                         "$fname: Expected mass commit of all peer transactions (DBO_TRX set)."
3470                                 );
3471                         }
3472                 }
3473
3474                 // Avoid fatals if close() was called
3475                 $this->assertOpen();
3476
3477                 $this->runOnTransactionPreCommitCallbacks();
3478                 $writeTime = $this->pendingWriteQueryDuration( self::ESTIMATE_DB_APPLY );
3479                 $this->doCommit( $fname );
3480                 if ( $this->trxDoneWrites ) {
3481                         $this->lastWriteTime = microtime( true );
3482                         $this->trxProfiler->transactionWritingOut(
3483                                 $this->server,
3484                                 $this->dbName,
3485                                 $this->trxShortId,
3486                                 $writeTime,
3487                                 $this->trxWriteAffectedRows
3488                         );
3489                 }
3490
3491                 $this->runOnTransactionIdleCallbacks( self::TRIGGER_COMMIT );
3492                 $this->runTransactionListenerCallbacks( self::TRIGGER_COMMIT );
3493         }
3494
3495         /**
3496          * Issues the COMMIT command to the database server.
3497          *
3498          * @see Database::commit()
3499          * @param string $fname
3500          */
3501         protected function doCommit( $fname ) {
3502                 if ( $this->trxLevel ) {
3503                         $this->query( 'COMMIT', $fname );
3504                         $this->trxLevel = 0;
3505                 }
3506         }
3507
3508         final public function rollback( $fname = __METHOD__, $flush = '' ) {
3509                 $trxActive = $this->trxLevel;
3510
3511                 if ( $flush !== self::FLUSHING_INTERNAL && $flush !== self::FLUSHING_ALL_PEERS ) {
3512                         if ( $this->getFlag( self::DBO_TRX ) ) {
3513                                 throw new DBUnexpectedError(
3514                                         $this,
3515                                         "$fname: Expected mass rollback of all peer transactions (DBO_TRX set)."
3516                                 );
3517                         }
3518                 }
3519
3520                 if ( $trxActive ) {
3521                         // Avoid fatals if close() was called
3522                         $this->assertOpen();
3523
3524                         $this->doRollback( $fname );
3525                         $this->trxAtomicLevels = [];
3526                         if ( $this->trxDoneWrites ) {
3527                                 $this->trxProfiler->transactionWritingOut(
3528                                         $this->server,
3529                                         $this->dbName,
3530                                         $this->trxShortId
3531                                 );
3532                         }
3533                 }
3534
3535                 // Clear any commit-dependant callbacks. They might even be present
3536                 // only due to transaction rounds, with no SQL transaction being active
3537                 $this->trxIdleCallbacks = [];
3538                 $this->trxPreCommitCallbacks = [];
3539
3540                 if ( $trxActive ) {
3541                         try {
3542                                 $this->runOnTransactionIdleCallbacks( self::TRIGGER_ROLLBACK );
3543                         } catch ( Exception $e ) {
3544                                 // already logged; finish and let LoadBalancer move on during mass-rollback
3545                         }
3546                         try {
3547                                 $this->runTransactionListenerCallbacks( self::TRIGGER_ROLLBACK );
3548                         } catch ( Exception $e ) {
3549                                 // already logged; let LoadBalancer move on during mass-rollback
3550                         }
3551
3552                         $this->affectedRowCount = 0; // for the sake of consistency
3553                 }
3554         }
3555
3556         /**
3557          * Issues the ROLLBACK command to the database server.
3558          *
3559          * @see Database::rollback()
3560          * @param string $fname
3561          */
3562         protected function doRollback( $fname ) {
3563                 if ( $this->trxLevel ) {
3564                         # Disconnects cause rollback anyway, so ignore those errors
3565                         $ignoreErrors = true;
3566                         $this->query( 'ROLLBACK', $fname, $ignoreErrors );
3567                         $this->trxLevel = 0;
3568                 }
3569         }
3570
3571         public function flushSnapshot( $fname = __METHOD__ ) {
3572                 if ( $this->writesOrCallbacksPending() || $this->explicitTrxActive() ) {
3573                         // This only flushes transactions to clear snapshots, not to write data
3574                         $fnames = implode( ', ', $this->pendingWriteAndCallbackCallers() );
3575                         throw new DBUnexpectedError(
3576                                 $this,
3577                                 "$fname: Cannot flush snapshot because writes are pending ($fnames)."
3578                         );
3579                 }
3580
3581                 $this->commit( $fname, self::FLUSHING_INTERNAL );
3582         }
3583
3584         public function explicitTrxActive() {
3585                 return $this->trxLevel && ( $this->trxAtomicLevels || !$this->trxAutomatic );
3586         }
3587
3588         public function duplicateTableStructure(
3589                 $oldName, $newName, $temporary = false, $fname = __METHOD__
3590         ) {
3591                 throw new RuntimeException( __METHOD__ . ' is not implemented in descendant class' );
3592         }
3593
3594         public function listTables( $prefix = null, $fname = __METHOD__ ) {
3595                 throw new RuntimeException( __METHOD__ . ' is not implemented in descendant class' );
3596         }
3597
3598         public function listViews( $prefix = null, $fname = __METHOD__ ) {
3599                 throw new RuntimeException( __METHOD__ . ' is not implemented in descendant class' );
3600         }
3601
3602         public function timestamp( $ts = 0 ) {
3603                 $t = new ConvertibleTimestamp( $ts );
3604                 // Let errors bubble up to avoid putting garbage in the DB
3605                 return $t->getTimestamp( TS_MW );
3606         }
3607
3608         public function timestampOrNull( $ts = null ) {
3609                 if ( is_null( $ts ) ) {
3610                         return null;
3611                 } else {
3612                         return $this->timestamp( $ts );
3613                 }
3614         }
3615
3616         public function affectedRows() {
3617                 return ( $this->affectedRowCount === null )
3618                         ? $this->fetchAffectedRowCount() // default to driver value
3619                         : $this->affectedRowCount;
3620         }
3621
3622         /**
3623          * @return int Number of retrieved rows according to the driver
3624          */
3625         abstract protected function fetchAffectedRowCount();
3626
3627         /**
3628          * Take the result from a query, and wrap it in a ResultWrapper if
3629          * necessary. Boolean values are passed through as is, to indicate success
3630          * of write queries or failure.
3631          *
3632          * Once upon a time, Database::query() returned a bare MySQL result
3633          * resource, and it was necessary to call this function to convert it to
3634          * a wrapper. Nowadays, raw database objects are never exposed to external
3635          * callers, so this is unnecessary in external code.
3636          *
3637          * @param bool|ResultWrapper|resource|object $result
3638          * @return bool|ResultWrapper
3639          */
3640         protected function resultObject( $result ) {
3641                 if ( !$result ) {
3642                         return false;
3643                 } elseif ( $result instanceof ResultWrapper ) {
3644                         return $result;
3645                 } elseif ( $result === true ) {
3646                         // Successful write query
3647                         return $result;
3648                 } else {
3649                         return new ResultWrapper( $this, $result );
3650                 }
3651         }
3652
3653         public function ping( &$rtt = null ) {
3654                 // Avoid hitting the server if it was hit recently
3655                 if ( $this->isOpen() && ( microtime( true ) - $this->lastPing ) < self::PING_TTL ) {
3656                         if ( !func_num_args() || $this->rttEstimate > 0 ) {
3657                                 $rtt = $this->rttEstimate;
3658                                 return true; // don't care about $rtt
3659                         }
3660                 }
3661
3662                 // This will reconnect if possible or return false if not
3663                 $this->clearFlag( self::DBO_TRX, self::REMEMBER_PRIOR );
3664                 $ok = ( $this->query( self::PING_QUERY, __METHOD__, true ) !== false );
3665                 $this->restoreFlags( self::RESTORE_PRIOR );
3666
3667                 if ( $ok ) {
3668                         $rtt = $this->rttEstimate;
3669                 }
3670
3671                 return $ok;
3672         }
3673
3674         /**
3675          * Close any existing (dead) database connection and open a new connection
3676          *
3677          * @param string $fname
3678          * @return bool True if new connection is opened successfully, false if error
3679          */
3680         protected function replaceLostConnection( $fname ) {
3681                 $this->closeConnection();
3682                 $this->opened = false;
3683                 $this->conn = false;
3684                 try {
3685                         $this->open( $this->server, $this->user, $this->password, $this->dbName );
3686                         $this->lastPing = microtime( true );
3687                         $ok = true;
3688
3689                         $this->connLogger->warning(
3690                                 $fname . ': lost connection to {dbserver}; reconnected',
3691                                 [
3692                                         'dbserver' => $this->getServer(),
3693                                         'trace' => ( new RuntimeException() )->getTraceAsString()
3694                                 ]
3695                         );
3696                 } catch ( DBConnectionError $e ) {
3697                         $ok = false;
3698
3699                         $this->connLogger->error(
3700                                 $fname . ': lost connection to {dbserver} permanently',
3701                                 [ 'dbserver' => $this->getServer() ]
3702                         );
3703                 }
3704
3705                 $this->handleSessionLoss();
3706
3707                 return $ok;
3708         }
3709
3710         public function getSessionLagStatus() {
3711                 return $this->getRecordedTransactionLagStatus() ?: $this->getApproximateLagStatus();
3712         }
3713
3714         /**
3715          * Get the replica DB lag when the current transaction started
3716          *
3717          * This is useful when transactions might use snapshot isolation
3718          * (e.g. REPEATABLE-READ in innodb), so the "real" lag of that data
3719          * is this lag plus transaction duration. If they don't, it is still
3720          * safe to be pessimistic. This returns null if there is no transaction.
3721          *
3722          * This returns null if the lag status for this transaction was not yet recorded.
3723          *
3724          * @return array|null ('lag': seconds or false on error, 'since': UNIX timestamp of BEGIN)
3725          * @since 1.27
3726          */
3727         final protected function getRecordedTransactionLagStatus() {
3728                 return ( $this->trxLevel && $this->trxReplicaLag !== null )
3729                         ? [ 'lag' => $this->trxReplicaLag, 'since' => $this->trxTimestamp() ]
3730                         : null;
3731         }
3732
3733         /**
3734          * Get a replica DB lag estimate for this server
3735          *
3736          * @return array ('lag': seconds or false on error, 'since': UNIX timestamp of estimate)
3737          * @since 1.27
3738          */
3739         protected function getApproximateLagStatus() {
3740                 return [
3741                         'lag'   => $this->getLBInfo( 'replica' ) ? $this->getLag() : 0,
3742                         'since' => microtime( true )
3743                 ];
3744         }
3745
3746         /**
3747          * Merge the result of getSessionLagStatus() for several DBs
3748          * using the most pessimistic values to estimate the lag of
3749          * any data derived from them in combination
3750          *
3751          * This is information is useful for caching modules
3752          *
3753          * @see WANObjectCache::set()
3754          * @see WANObjectCache::getWithSetCallback()
3755          *
3756          * @param IDatabase $db1
3757          * @param IDatabase $db2 [optional]
3758          * @return array Map of values:
3759          *   - lag: highest lag of any of the DBs or false on error (e.g. replication stopped)
3760          *   - since: oldest UNIX timestamp of any of the DB lag estimates
3761          *   - pending: whether any of the DBs have uncommitted changes
3762          * @throws DBError
3763          * @since 1.27
3764          */
3765         public static function getCacheSetOptions( IDatabase $db1, IDatabase $db2 = null ) {
3766                 $res = [ 'lag' => 0, 'since' => INF, 'pending' => false ];
3767                 foreach ( func_get_args() as $db ) {
3768                         /** @var IDatabase $db */
3769                         $status = $db->getSessionLagStatus();
3770                         if ( $status['lag'] === false ) {
3771                                 $res['lag'] = false;
3772                         } elseif ( $res['lag'] !== false ) {
3773                                 $res['lag'] = max( $res['lag'], $status['lag'] );
3774                         }
3775                         $res['since'] = min( $res['since'], $status['since'] );
3776                         $res['pending'] = $res['pending'] ?: $db->writesPending();
3777                 }
3778
3779                 return $res;
3780         }
3781
3782         public function getLag() {
3783                 return 0;
3784         }
3785
3786         public function maxListLen() {
3787                 return 0;
3788         }
3789
3790         public function encodeBlob( $b ) {
3791                 return $b;
3792         }
3793
3794         public function decodeBlob( $b ) {
3795                 if ( $b instanceof Blob ) {
3796                         $b = $b->fetch();
3797                 }
3798                 return $b;
3799         }
3800
3801         public function setSessionOptions( array $options ) {
3802         }
3803
3804         public function sourceFile(
3805                 $filename,
3806                 callable $lineCallback = null,
3807                 callable $resultCallback = null,
3808                 $fname = false,
3809                 callable $inputCallback = null
3810         ) {
3811                 Wikimedia\suppressWarnings();
3812                 $fp = fopen( $filename, 'r' );
3813                 Wikimedia\restoreWarnings();
3814
3815                 if ( false === $fp ) {
3816                         throw new RuntimeException( "Could not open \"{$filename}\".\n" );
3817                 }
3818
3819                 if ( !$fname ) {
3820                         $fname = __METHOD__ . "( $filename )";
3821                 }
3822
3823                 try {
3824                         $error = $this->sourceStream(
3825                                 $fp, $lineCallback, $resultCallback, $fname, $inputCallback );
3826                 } catch ( Exception $e ) {
3827                         fclose( $fp );
3828                         throw $e;
3829                 }
3830
3831                 fclose( $fp );
3832
3833                 return $error;
3834         }
3835
3836         public function setSchemaVars( $vars ) {
3837                 $this->schemaVars = $vars;
3838         }
3839
3840         public function sourceStream(
3841                 $fp,
3842                 callable $lineCallback = null,
3843                 callable $resultCallback = null,
3844                 $fname = __METHOD__,
3845                 callable $inputCallback = null
3846         ) {
3847                 $delimiterReset = new ScopedCallback(
3848                         function ( $delimiter ) {
3849                                 $this->delimiter = $delimiter;
3850                         },
3851                         [ $this->delimiter ]
3852                 );
3853                 $cmd = '';
3854
3855                 while ( !feof( $fp ) ) {
3856                         if ( $lineCallback ) {
3857                                 call_user_func( $lineCallback );
3858                         }
3859
3860                         $line = trim( fgets( $fp ) );
3861
3862                         if ( $line == '' ) {
3863                                 continue;
3864                         }
3865
3866                         if ( '-' == $line[0] && '-' == $line[1] ) {
3867                                 continue;
3868                         }
3869
3870                         if ( $cmd != '' ) {
3871                                 $cmd .= ' ';
3872                         }
3873
3874                         $done = $this->streamStatementEnd( $cmd, $line );
3875
3876                         $cmd .= "$line\n";
3877
3878                         if ( $done || feof( $fp ) ) {
3879                                 $cmd = $this->replaceVars( $cmd );
3880
3881                                 if ( $inputCallback ) {
3882                                         $callbackResult = call_user_func( $inputCallback, $cmd );
3883
3884                                         if ( is_string( $callbackResult ) || !$callbackResult ) {
3885                                                 $cmd = $callbackResult;
3886                                         }
3887                                 }
3888
3889                                 if ( $cmd ) {
3890                                         $res = $this->query( $cmd, $fname );
3891
3892                                         if ( $resultCallback ) {
3893                                                 call_user_func( $resultCallback, $res, $this );
3894                                         }
3895
3896                                         if ( false === $res ) {
3897                                                 $err = $this->lastError();
3898
3899                                                 return "Query \"{$cmd}\" failed with error code \"$err\".\n";
3900                                         }
3901                                 }
3902                                 $cmd = '';
3903                         }
3904                 }
3905
3906                 ScopedCallback::consume( $delimiterReset );
3907                 return true;
3908         }
3909
3910         /**
3911          * Called by sourceStream() to check if we've reached a statement end
3912          *
3913          * @param string &$sql SQL assembled so far
3914          * @param string &$newLine New line about to be added to $sql
3915          * @return bool Whether $newLine contains end of the statement
3916          */
3917         public function streamStatementEnd( &$sql, &$newLine ) {
3918                 if ( $this->delimiter ) {
3919                         $prev = $newLine;
3920                         $newLine = preg_replace(
3921                                 '/' . preg_quote( $this->delimiter, '/' ) . '$/', '', $newLine );
3922                         if ( $newLine != $prev ) {
3923                                 return true;
3924                         }
3925                 }
3926
3927                 return false;
3928         }
3929
3930         /**
3931          * Database independent variable replacement. Replaces a set of variables
3932          * in an SQL statement with their contents as given by $this->getSchemaVars().
3933          *
3934          * Supports '{$var}' `{$var}` and / *$var* / (without the spaces) style variables.
3935          *
3936          * - '{$var}' should be used for text and is passed through the database's
3937          *   addQuotes method.
3938          * - `{$var}` should be used for identifiers (e.g. table and database names).
3939          *   It is passed through the database's addIdentifierQuotes method which
3940          *   can be overridden if the database uses something other than backticks.
3941          * - / *_* / or / *$wgDBprefix* / passes the name that follows through the
3942          *   database's tableName method.
3943          * - / *i* / passes the name that follows through the database's indexName method.
3944          * - In all other cases, / *$var* / is left unencoded. Except for table options,
3945          *   its use should be avoided. In 1.24 and older, string encoding was applied.
3946          *
3947          * @param string $ins SQL statement to replace variables in
3948          * @return string The new SQL statement with variables replaced
3949          */
3950         protected function replaceVars( $ins ) {
3951                 $vars = $this->getSchemaVars();
3952                 return preg_replace_callback(
3953                         '!
3954                                 /\* (\$wgDBprefix|[_i]) \*/ (\w*) | # 1-2. tableName, indexName
3955                                 \'\{\$ (\w+) }\'                  | # 3. addQuotes
3956                                 `\{\$ (\w+) }`                    | # 4. addIdentifierQuotes
3957                                 /\*\$ (\w+) \*/                     # 5. leave unencoded
3958                         !x',
3959                         function ( $m ) use ( $vars ) {
3960                                 // Note: Because of <https://bugs.php.net/bug.php?id=51881>,
3961                                 // check for both nonexistent keys *and* the empty string.
3962                                 if ( isset( $m[1] ) && $m[1] !== '' ) {
3963                                         if ( $m[1] === 'i' ) {
3964                                                 return $this->indexName( $m[2] );
3965                                         } else {
3966                                                 return $this->tableName( $m[2] );
3967                                         }
3968                                 } elseif ( isset( $m[3] ) && $m[3] !== '' && array_key_exists( $m[3], $vars ) ) {
3969                                         return $this->addQuotes( $vars[$m[3]] );
3970                                 } elseif ( isset( $m[4] ) && $m[4] !== '' && array_key_exists( $m[4], $vars ) ) {
3971                                         return $this->addIdentifierQuotes( $vars[$m[4]] );
3972                                 } elseif ( isset( $m[5] ) && $m[5] !== '' && array_key_exists( $m[5], $vars ) ) {
3973                                         return $vars[$m[5]];
3974                                 } else {
3975                                         return $m[0];
3976                                 }
3977                         },
3978                         $ins
3979                 );
3980         }
3981
3982         /**
3983          * Get schema variables. If none have been set via setSchemaVars(), then
3984          * use some defaults from the current object.
3985          *
3986          * @return array
3987          */
3988         protected function getSchemaVars() {
3989                 if ( $this->schemaVars ) {
3990                         return $this->schemaVars;
3991                 } else {
3992                         return $this->getDefaultSchemaVars();
3993                 }
3994         }
3995
3996         /**
3997          * Get schema variables to use if none have been set via setSchemaVars().
3998          *
3999          * Override this in derived classes to provide variables for tables.sql
4000          * and SQL patch files.
4001          *
4002          * @return array
4003          */
4004         protected function getDefaultSchemaVars() {
4005                 return [];
4006         }
4007
4008         public function lockIsFree( $lockName, $method ) {
4009                 // RDBMs methods for checking named locks may or may not count this thread itself.
4010                 // In MySQL, IS_FREE_LOCK() returns 0 if the thread already has the lock. This is
4011                 // the behavior choosen by the interface for this method.
4012                 return !isset( $this->namedLocksHeld[$lockName] );
4013         }
4014
4015         public function lock( $lockName, $method, $timeout = 5 ) {
4016                 $this->namedLocksHeld[$lockName] = 1;
4017
4018                 return true;
4019         }
4020
4021         public function unlock( $lockName, $method ) {
4022                 unset( $this->namedLocksHeld[$lockName] );
4023
4024                 return true;
4025         }
4026
4027         public function getScopedLockAndFlush( $lockKey, $fname, $timeout ) {
4028                 if ( $this->writesOrCallbacksPending() ) {
4029                         // This only flushes transactions to clear snapshots, not to write data
4030                         $fnames = implode( ', ', $this->pendingWriteAndCallbackCallers() );
4031                         throw new DBUnexpectedError(
4032                                 $this,
4033                                 "$fname: Cannot flush pre-lock snapshot because writes are pending ($fnames)."
4034                         );
4035                 }
4036
4037                 if ( !$this->lock( $lockKey, $fname, $timeout ) ) {
4038                         return null;
4039                 }
4040
4041                 $unlocker = new ScopedCallback( function () use ( $lockKey, $fname ) {
4042                         if ( $this->trxLevel() ) {
4043                                 // There is a good chance an exception was thrown, causing any early return
4044                                 // from the caller. Let any error handler get a chance to issue rollback().
4045                                 // If there isn't one, let the error bubble up and trigger server-side rollback.
4046                                 $this->onTransactionResolution(
4047                                         function () use ( $lockKey, $fname ) {
4048                                                 $this->unlock( $lockKey, $fname );
4049                                         },
4050                                         $fname
4051                                 );
4052                         } else {
4053                                 $this->unlock( $lockKey, $fname );
4054                         }
4055                 } );
4056
4057                 $this->commit( $fname, self::FLUSHING_INTERNAL );
4058
4059                 return $unlocker;
4060         }
4061
4062         public function namedLocksEnqueue() {
4063                 return false;
4064         }
4065
4066         public function tableLocksHaveTransactionScope() {
4067                 return true;
4068         }
4069
4070         final public function lockTables( array $read, array $write, $method ) {
4071                 if ( $this->writesOrCallbacksPending() ) {
4072                         throw new DBUnexpectedError( $this, "Transaction writes or callbacks still pending." );
4073                 }
4074
4075                 if ( $this->tableLocksHaveTransactionScope() ) {
4076                         $this->startAtomic( $method );
4077                 }
4078
4079                 return $this->doLockTables( $read, $write, $method );
4080         }
4081
4082         /**
4083          * Helper function for lockTables() that handles the actual table locking
4084          *
4085          * @param array $read Array of tables to lock for read access
4086          * @param array $write Array of tables to lock for write access
4087          * @param string $method Name of caller
4088          * @return true
4089          */
4090         protected function doLockTables( array $read, array $write, $method ) {
4091                 return true;
4092         }
4093
4094         final public function unlockTables( $method ) {
4095                 if ( $this->tableLocksHaveTransactionScope() ) {
4096                         $this->endAtomic( $method );
4097
4098                         return true; // locks released on COMMIT/ROLLBACK
4099                 }
4100
4101                 return $this->doUnlockTables( $method );
4102         }
4103
4104         /**
4105          * Helper function for unlockTables() that handles the actual table unlocking
4106          *
4107          * @param string $method Name of caller
4108          * @return true
4109          */
4110         protected function doUnlockTables( $method ) {
4111                 return true;
4112         }
4113
4114         /**
4115          * Delete a table
4116          * @param string $tableName
4117          * @param string $fName
4118          * @return bool|ResultWrapper
4119          * @since 1.18
4120          */
4121         public function dropTable( $tableName, $fName = __METHOD__ ) {
4122                 if ( !$this->tableExists( $tableName, $fName ) ) {
4123                         return false;
4124                 }
4125                 $sql = "DROP TABLE " . $this->tableName( $tableName ) . " CASCADE";
4126
4127                 return $this->query( $sql, $fName );
4128         }
4129
4130         public function getInfinity() {
4131                 return 'infinity';
4132         }
4133
4134         public function encodeExpiry( $expiry ) {
4135                 return ( $expiry == '' || $expiry == 'infinity' || $expiry == $this->getInfinity() )
4136                         ? $this->getInfinity()
4137                         : $this->timestamp( $expiry );
4138         }
4139
4140         public function decodeExpiry( $expiry, $format = TS_MW ) {
4141                 if ( $expiry == '' || $expiry == 'infinity' || $expiry == $this->getInfinity() ) {
4142                         return 'infinity';
4143                 }
4144
4145                 return ConvertibleTimestamp::convert( $format, $expiry );
4146         }
4147
4148         public function setBigSelects( $value = true ) {
4149                 // no-op
4150         }
4151
4152         public function isReadOnly() {
4153                 return ( $this->getReadOnlyReason() !== false );
4154         }
4155
4156         /**
4157          * @return string|bool Reason this DB is read-only or false if it is not
4158          */
4159         protected function getReadOnlyReason() {
4160                 $reason = $this->getLBInfo( 'readOnlyReason' );
4161
4162                 return is_string( $reason ) ? $reason : false;
4163         }
4164
4165         public function setTableAliases( array $aliases ) {
4166                 $this->tableAliases = $aliases;
4167         }
4168
4169         public function setIndexAliases( array $aliases ) {
4170                 $this->indexAliases = $aliases;
4171         }
4172
4173         /**
4174          * Get the underlying binding connection handle
4175          *
4176          * Makes sure the connection resource is set (disconnects and ping() failure can unset it).
4177          * This catches broken callers than catch and ignore disconnection exceptions.
4178          * Unlike checking isOpen(), this is safe to call inside of open().
4179          *
4180          * @return mixed
4181          * @throws DBUnexpectedError
4182          * @since 1.26
4183          */
4184         protected function getBindingHandle() {
4185                 if ( !$this->conn ) {
4186                         throw new DBUnexpectedError(
4187                                 $this,
4188                                 'DB connection was already closed or the connection dropped.'
4189                         );
4190                 }
4191
4192                 return $this->conn;
4193         }
4194
4195         /**
4196          * @since 1.19
4197          * @return string
4198          */
4199         public function __toString() {
4200                 return (string)$this->conn;
4201         }
4202
4203         /**
4204          * Make sure that copies do not share the same client binding handle
4205          * @throws DBConnectionError
4206          */
4207         public function __clone() {
4208                 $this->connLogger->warning(
4209                         "Cloning " . static::class . " is not recomended; forking connection:\n" .
4210                         ( new RuntimeException() )->getTraceAsString()
4211                 );
4212
4213                 if ( $this->isOpen() ) {
4214                         // Open a new connection resource without messing with the old one
4215                         $this->opened = false;
4216                         $this->conn = false;
4217                         $this->trxEndCallbacks = []; // don't copy
4218                         $this->handleSessionLoss(); // no trx or locks anymore
4219                         $this->open( $this->server, $this->user, $this->password, $this->dbName );
4220                         $this->lastPing = microtime( true );
4221                 }
4222         }
4223
4224         /**
4225          * Called by serialize. Throw an exception when DB connection is serialized.
4226          * This causes problems on some database engines because the connection is
4227          * not restored on unserialize.
4228          */
4229         public function __sleep() {
4230                 throw new RuntimeException( 'Database serialization may cause problems, since ' .
4231                         'the connection is not restored on wakeup.' );
4232         }
4233
4234         /**
4235          * Run a few simple sanity checks and close dangling connections
4236          */
4237         public function __destruct() {
4238                 if ( $this->trxLevel && $this->trxDoneWrites ) {
4239                         trigger_error( "Uncommitted DB writes (transaction from {$this->trxFname})." );
4240                 }
4241
4242                 $danglingWriters = $this->pendingWriteAndCallbackCallers();
4243                 if ( $danglingWriters ) {
4244                         $fnames = implode( ', ', $danglingWriters );
4245                         trigger_error( "DB transaction writes or callbacks still pending ($fnames)." );
4246                 }
4247
4248                 if ( $this->conn ) {
4249                         // Avoid connection leaks for sanity. Normally, resources close at script completion.
4250                         // The connection might already be closed in zend/hhvm by now, so suppress warnings.
4251                         Wikimedia\suppressWarnings();
4252                         $this->closeConnection();
4253                         Wikimedia\restoreWarnings();
4254                         $this->conn = false;
4255                         $this->opened = false;
4256                 }
4257         }
4258 }
4259
4260 class_alias( Database::class, 'DatabaseBase' ); // b/c for old name
4261 class_alias( Database::class, 'Database' ); // b/c global alias