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         /** @var callback Deprecation logging callback */
 105         protected $deprecationLogger;
 106
 107         /** @var resource|null Database connection */
 108         protected $conn = null;
 109         /** @var bool */
 110         protected $opened = false;
 111
 112         /** @var array[] List of (callable, method name, atomic section id) */
 113         protected $trxIdleCallbacks = [];
 114         /** @var array[] List of (callable, method name, atomic section id) */
 115         protected $trxPreCommitCallbacks = [];
 116         /** @var array[] List of (callable, method name, atomic section id) */
 117         protected $trxEndCallbacks = [];
 118         /** @var callable[] Map of (name => callable) */
 119         protected $trxRecurringCallbacks = [];
 120         /** @var bool Whether to suppress triggering of transaction end callbacks */
 121         protected $trxEndCallbacksSuppressed = false;
 122
 123         /** @var string */
 124         protected $tablePrefix = '';
 125         /** @var string */
 126         protected $schema = '';
 127         /** @var int */
 128         protected $flags;
 129         /** @var array */
 130         protected $lbInfo = [];
 131         /** @var array|bool */
 132         protected $schemaVars = false;
 133         /** @var array */
 134         protected $sessionVars = [];
 135         /** @var array|null */
 136         protected $preparedArgs;
 137         /** @var string|bool|null Stashed value of html_errors INI setting */
 138         protected $htmlErrors;
 139         /** @var string */
 140         protected $delimiter = ';';
 141         /** @var DatabaseDomain */
 142         protected $currentDomain;
 143         /** @var integer|null Rows affected by the last query to query() or its CRUD wrappers */
 144         protected $affectedRowCount;
 145
 146         /**
 147          * @var int Transaction status
 148          */
 149         protected $trxStatus = self::STATUS_TRX_NONE;
 150         /**
 151          * @var Exception|null The last error that caused the status to become STATUS_TRX_ERROR
 152          */
 153         protected $trxStatusCause;
 154         /**
 155          * @var array|null If wasKnownStatementRollbackError() prevented trxStatus from being set,
 156          *  the relevant details are stored here.
 157          */
 158         protected $trxStatusIgnoredCause;
 159         /**
 160          * Either 1 if a transaction is active or 0 otherwise.
 161          * The other Trx fields may not be meaningfull if this is 0.
 162          *
 163          * @var int
 164          */
 165         protected $trxLevel = 0;
 166         /**
 167          * Either a short hexidecimal string if a transaction is active or ""
 168          *
 169          * @var string
 170          * @see Database::trxLevel
 171          */
 172         protected $trxShortId = '';
 173         /**
 174          * The UNIX time that the transaction started. Callers can assume that if
 175          * snapshot isolation is used, then the data is *at least* up to date to that
 176          * point (possibly more up-to-date since the first SELECT defines the snapshot).
 177          *
 178          * @var float|null
 179          * @see Database::trxLevel
 180          */
 181         private $trxTimestamp = null;
 182         /** @var float Lag estimate at the time of BEGIN */
 183         private $trxReplicaLag = null;
 184         /**
 185          * Remembers the function name given for starting the most recent transaction via begin().
 186          * Used to provide additional context for error reporting.
 187          *
 188          * @var string
 189          * @see Database::trxLevel
 190          */
 191         private $trxFname = null;
 192         /**
 193          * Record if possible write queries were done in the last transaction started
 194          *
 195          * @var bool
 196          * @see Database::trxLevel
 197          */
 198         private $trxDoneWrites = false;
 199         /**
 200          * Record if the current transaction was started implicitly due to DBO_TRX being set.
 201          *
 202          * @var bool
 203          * @see Database::trxLevel
 204          */
 205         private $trxAutomatic = false;
 206         /**
 207          * Counter for atomic savepoint identifiers. Reset when a new transaction begins.
 208          *
 209          * @var int
 210          */
 211         private $trxAtomicCounter = 0;
 212         /**
 213          * Array of levels of atomicity within transactions
 214          *
 215          * @var array List of (name, unique ID, savepoint ID)
 216          */
 217         private $trxAtomicLevels = [];
 218         /**
 219          * Record if the current transaction was started implicitly by Database::startAtomic
 220          *
 221          * @var bool
 222          */
 223         private $trxAutomaticAtomic = false;
 224         /**
 225          * Track the write query callers of the current transaction
 226          *
 227          * @var string[]
 228          */
 229         private $trxWriteCallers = [];
 230         /**
 231          * @var float Seconds spent in write queries for the current transaction
 232          */
 233         private $trxWriteDuration = 0.0;
 234         /**
 235          * @var int Number of write queries for the current transaction
 236          */
 237         private $trxWriteQueryCount = 0;
 238         /**
 239          * @var int Number of rows affected by write queries for the current transaction
 240          */
 241         private $trxWriteAffectedRows = 0;
 242         /**
 243          * @var float Like trxWriteQueryCount but excludes lock-bound, easy to replicate, queries
 244          */
 245         private $trxWriteAdjDuration = 0.0;
 246         /**
 247          * @var int Number of write queries counted in trxWriteAdjDuration
 248          */
 249         private $trxWriteAdjQueryCount = 0;
 250         /**
 251          * @var float RTT time estimate
 252          */
 253         private $rttEstimate = 0.0;
 254
 255         /** @var array Map of (name => 1) for locks obtained via lock() */
 256         private $namedLocksHeld = [];
 257         /** @var array Map of (table name => 1) for TEMPORARY tables */
 258         protected $sessionTempTables = [];
 259
 260         /** @var IDatabase|null Lazy handle to the master DB this server replicates from */
 261         private $lazyMasterHandle;
 262
 263         /** @var float UNIX timestamp */
 264         protected $lastPing = 0.0;
 265
 266         /** @var int[] Prior flags member variable values */
 267         private $priorFlags = [];
 268
 269         /** @var object|string Class name or object With profileIn/profileOut methods */
 270         protected $profiler;
 271         /** @var TransactionProfiler */
 272         protected $trxProfiler;
 273
 274         /** @var int */
 275         protected $nonNativeInsertSelectBatchSize = 10000;
 276
 277         /** @var string Idiom used when a cancelable atomic section started the transaction */
 278         private static $NOT_APPLICABLE = 'n/a';
 279         /** @var string Prefix to the atomic section counter used to make savepoint IDs */
 280         private static $SAVEPOINT_PREFIX = 'wikimedia_rdbms_atomic';
 281
 282         /** @var int Transaction is in a error state requiring a full or savepoint rollback */
 283         const STATUS_TRX_ERROR = 1;
 284         /** @var int Transaction is active and in a normal state */
 285         const STATUS_TRX_OK = 2;
 286         /** @var int No transaction is active */
 287         const STATUS_TRX_NONE = 3;
 288
 289         /**
 290          * @note: exceptions for missing libraries/drivers should be thrown in initConnection()
 291          * @param array $params Parameters passed from Database::factory()
 292          */
 293         protected function __construct( array $params ) {
 294                 foreach ( [ 'host', 'user', 'password', 'dbname' ] as $name ) {
 295                         $this->connectionParams[$name] = $params[$name];
 296                 }
 297
 298                 $this->schema = $params['schema'];
 299                 $this->tablePrefix = $params['tablePrefix'];
 300
 301                 $this->cliMode = $params['cliMode'];
 302                 // Agent name is added to SQL queries in a comment, so make sure it can't break out
 303                 $this->agent = str_replace( '/', '-', $params['agent'] );
 304
 305                 $this->flags = $params['flags'];
 306                 if ( $this->flags & self::DBO_DEFAULT ) {
 307                         if ( $this->cliMode ) {
 308                                 $this->flags &= ~self::DBO_TRX;
 309                         } else {
 310                                 $this->flags |= self::DBO_TRX;
 311                         }
 312                 }
 313                 // Disregard deprecated DBO_IGNORE flag (T189999)
 314                 $this->flags &= ~self::DBO_IGNORE;
 315
 316                 $this->sessionVars = $params['variables'];
 317
 318                 $this->srvCache = isset( $params['srvCache'] )
 319                         ? $params['srvCache']
 320                         : new HashBagOStuff();
 321
 322                 $this->profiler = $params['profiler'];
 323                 $this->trxProfiler = $params['trxProfiler'];
 324                 $this->connLogger = $params['connLogger'];
 325                 $this->queryLogger = $params['queryLogger'];
 326                 $this->errorLogger = $params['errorLogger'];
 327                 $this->deprecationLogger = $params['deprecationLogger'];
 328
 329                 if ( isset( $params['nonNativeInsertSelectBatchSize'] ) ) {
 330                         $this->nonNativeInsertSelectBatchSize = $params['nonNativeInsertSelectBatchSize'];
 331                 }
 332
 333                 // Set initial dummy domain until open() sets the final DB/prefix
 334                 $this->currentDomain = DatabaseDomain::newUnspecified();
 335         }
 336
 337         /**
 338          * Initialize the connection to the database over the wire (or to local files)
 339          *
 340          * @throws LogicException
 341          * @throws InvalidArgumentException
 342          * @throws DBConnectionError
 343          * @since 1.31
 344          */
 345         final public function initConnection() {
 346                 if ( $this->isOpen() ) {
 347                         throw new LogicException( __METHOD__ . ': already connected.' );
 348                 }
 349                 // Establish the connection
 350                 $this->doInitConnection();
 351                 // Set the domain object after open() sets the relevant fields
 352                 if ( $this->dbName != '' ) {
 353                         // Domains with server scope but a table prefix are not used by IDatabase classes
 354                         $this->currentDomain = new DatabaseDomain( $this->dbName, null, $this->tablePrefix );
 355                 }
 356         }
 357
 358         /**
 359          * Actually connect to the database over the wire (or to local files)
 360          *
 361          * @throws InvalidArgumentException
 362          * @throws DBConnectionError
 363          * @since 1.31
 364          */
 365         protected function doInitConnection() {
 366                 if ( strlen( $this->connectionParams['user'] ) ) {
 367                         $this->open(
 368                                 $this->connectionParams['host'],
 369                                 $this->connectionParams['user'],
 370                                 $this->connectionParams['password'],
 371                                 $this->connectionParams['dbname']
 372                         );
 373                 } else {
 374                         throw new InvalidArgumentException( "No database user provided." );
 375                 }
 376         }
 377
 378         /**
 379          * Construct a Database subclass instance given a database type and parameters
 380          *
 381          * This also connects to the database immediately upon object construction
 382          *
 383          * @param string $dbType A possible DB type (sqlite, mysql, postgres,...)
 384          * @param array $p Parameter map with keys:
 385          *   - host : The hostname of the DB server
 386          *   - user : The name of the database user the client operates under
 387          *   - password : The password for the database user
 388          *   - dbname : The name of the database to use where queries do not specify one.
 389          *      The database must exist or an error might be thrown. Setting this to the empty string
 390          *      will avoid any such errors and make the handle have no implicit database scope. This is
 391          *      useful for queries like SHOW STATUS, CREATE DATABASE, or DROP DATABASE. Note that a
 392          *      "database" in Postgres is rougly equivalent to an entire MySQL server. This the domain
 393          *      in which user names and such are defined, e.g. users are database-specific in Postgres.
 394          *   - schema : The database schema to use (if supported). A "schema" in Postgres is roughly
 395          *      equivalent to a "database" in MySQL. Note that MySQL and SQLite do not use schemas.
 396          *   - tablePrefix : Optional table prefix that is implicitly added on to all table names
 397          *      recognized in queries. This can be used in place of schemas for handle site farms.
 398          *   - flags : Optional bitfield of DBO_* constants that define connection, protocol,
 399          *      buffering, and transaction behavior. It is STRONGLY adviced to leave the DBO_DEFAULT
 400          *      flag in place UNLESS this this database simply acts as a key/value store.
 401          *   - driver: Optional name of a specific DB client driver. For MySQL, there is only the
 402          *      'mysqli' driver; the old one 'mysql' has been removed.
 403          *   - variables: Optional map of session variables to set after connecting. This can be
 404          *      used to adjust lock timeouts or encoding modes and the like.
 405          *   - connLogger: Optional PSR-3 logger interface instance.
 406          *   - queryLogger: Optional PSR-3 logger interface instance.
 407          *   - profiler: Optional class name or object with profileIn()/profileOut() methods.
 408          *      These will be called in query(), using a simplified version of the SQL that also
 409          *      includes the agent as a SQL comment.
 410          *   - trxProfiler: Optional TransactionProfiler instance.
 411          *   - errorLogger: Optional callback that takes an Exception and logs it.
 412          *   - deprecationLogger: Optional callback that takes a string and logs it.
 413          *   - cliMode: Whether to consider the execution context that of a CLI script.
 414          *   - agent: Optional name used to identify the end-user in query profiling/logging.
 415          *   - srvCache: Optional BagOStuff instance to an APC-style cache.
 416          *   - nonNativeInsertSelectBatchSize: Optional batch size for non-native INSERT SELECT emulation.
 417          * @param int $connect One of the class constants (NEW_CONNECTED, NEW_UNCONNECTED) [optional]
 418          * @return Database|null If the database driver or extension cannot be found
 419          * @throws InvalidArgumentException If the database driver or extension cannot be found
 420          * @since 1.18
 421          */
 422         final public static function factory( $dbType, $p = [], $connect = self::NEW_CONNECTED ) {
 423                 $class = self::getClass( $dbType, isset( $p['driver'] ) ? $p['driver'] : null );
 424
 425                 if ( class_exists( $class ) && is_subclass_of( $class, IDatabase::class ) ) {
 426                         // Resolve some defaults for b/c
 427                         $p['host'] = isset( $p['host'] ) ? $p['host'] : false;
 428                         $p['user'] = isset( $p['user'] ) ? $p['user'] : false;
 429                         $p['password'] = isset( $p['password'] ) ? $p['password'] : false;
 430                         $p['dbname'] = isset( $p['dbname'] ) ? $p['dbname'] : false;
 431                         $p['flags'] = isset( $p['flags'] ) ? $p['flags'] : 0;
 432                         $p['variables'] = isset( $p['variables'] ) ? $p['variables'] : [];
 433                         $p['tablePrefix'] = isset( $p['tablePrefix'] ) ? $p['tablePrefix'] : '';
 434                         $p['schema'] = isset( $p['schema'] ) ? $p['schema'] : '';
 435                         $p['cliMode'] = isset( $p['cliMode'] )
 436                                 ? $p['cliMode']
 437                                 : ( PHP_SAPI === 'cli' || PHP_SAPI === 'phpdbg' );
 438                         $p['agent'] = isset( $p['agent'] ) ? $p['agent'] : '';
 439                         if ( !isset( $p['connLogger'] ) ) {
 440                                 $p['connLogger'] = new NullLogger();
 441                         }
 442                         if ( !isset( $p['queryLogger'] ) ) {
 443                                 $p['queryLogger'] = new NullLogger();
 444                         }
 445                         $p['profiler'] = isset( $p['profiler'] ) ? $p['profiler'] : null;
 446                         if ( !isset( $p['trxProfiler'] ) ) {
 447                                 $p['trxProfiler'] = new TransactionProfiler();
 448                         }
 449                         if ( !isset( $p['errorLogger'] ) ) {
 450                                 $p['errorLogger'] = function ( Exception $e ) {
 451                                         trigger_error( get_class( $e ) . ': ' . $e->getMessage(), E_USER_WARNING );
 452                                 };
 453                         }
 454                         if ( !isset( $p['deprecationLogger'] ) ) {
 455                                 $p['deprecationLogger'] = function ( $msg ) {
 456                                         trigger_error( $msg, E_USER_DEPRECATED );
 457                                 };
 458                         }
 459
 460                         /** @var Database $conn */
 461                         $conn = new $class( $p );
 462                         if ( $connect == self::NEW_CONNECTED ) {
 463                                 $conn->initConnection();
 464                         }
 465                 } else {
 466                         $conn = null;
 467                 }
 468
 469                 return $conn;
 470         }
 471
 472         /**
 473          * @param string $dbType A possible DB type (sqlite, mysql, postgres,...)
 474          * @param string|null $driver Optional name of a specific DB client driver
 475          * @return array Map of (Database::ATTRIBUTE_* constant => value) for all such constants
 476          * @throws InvalidArgumentException
 477          * @since 1.31
 478          */
 479         final public static function attributesFromType( $dbType, $driver = null ) {
 480                 static $defaults = [ self::ATTR_DB_LEVEL_LOCKING => false ];
 481
 482                 $class = self::getClass( $dbType, $driver );
 483
 484                 return call_user_func( [ $class, 'getAttributes' ] ) + $defaults;
 485         }
 486
 487         /**
 488          * @param string $dbType A possible DB type (sqlite, mysql, postgres,...)
 489          * @param string|null $driver Optional name of a specific DB client driver
 490          * @return string Database subclass name to use
 491          * @throws InvalidArgumentException
 492          */
 493         private static function getClass( $dbType, $driver = null ) {
 494                 // For database types with built-in support, the below maps type to IDatabase
 495                 // implementations. For types with multipe driver implementations (PHP extensions),
 496                 // an array can be used, keyed by extension name. In case of an array, the
 497                 // optional 'driver' parameter can be used to force a specific driver. Otherwise,
 498                 // we auto-detect the first available driver. For types without built-in support,
 499                 // an class named "Database<Type>" us used, eg. DatabaseFoo for type 'foo'.
 500                 static $builtinTypes = [
 501                         'mssql' => DatabaseMssql::class,
 502                         'mysql' => [ 'mysqli' => DatabaseMysqli::class ],
 503                         'sqlite' => DatabaseSqlite::class,
 504                         'postgres' => DatabasePostgres::class,
 505                 ];
 506
 507                 $dbType = strtolower( $dbType );
 508                 $class = false;
 509
 510                 if ( isset( $builtinTypes[$dbType] ) ) {
 511                         $possibleDrivers = $builtinTypes[$dbType];
 512                         if ( is_string( $possibleDrivers ) ) {
 513                                 $class = $possibleDrivers;
 514                         } else {
 515                                 if ( (string)$driver !== '' ) {
 516                                         if ( !isset( $possibleDrivers[$driver] ) ) {
 517                                                 throw new InvalidArgumentException( __METHOD__ .
 518                                                         " type '$dbType' does not support driver '{$driver}'" );
 519                                         } else {
 520                                                 $class = $possibleDrivers[$driver];
 521                                         }
 522                                 } else {
 523                                         foreach ( $possibleDrivers as $posDriver => $possibleClass ) {
 524                                                 if ( extension_loaded( $posDriver ) ) {
 525                                                         $class = $possibleClass;
 526                                                         break;
 527                                                 }
 528                                         }
 529                                 }
 530                         }
 531                 } else {
 532                         $class = 'Database' . ucfirst( $dbType );
 533                 }
 534
 535                 if ( $class === false ) {
 536                         throw new InvalidArgumentException( __METHOD__ .
 537                                 " no viable database extension found for type '$dbType'" );
 538                 }
 539
 540                 return $class;
 541         }
 542
 543         /**
 544          * @return array Map of (Database::ATTRIBUTE_* constant => value
 545          * @since 1.31
 546          */
 547         protected static function getAttributes() {
 548                 return [];
 549         }
 550
 551         /**
 552          * Set the PSR-3 logger interface to use for query logging. (The logger
 553          * interfaces for connection logging and error logging can be set with the
 554          * constructor.)
 555          *
 556          * @param LoggerInterface $logger
 557          */
 558         public function setLogger( LoggerInterface $logger ) {
 559                 $this->queryLogger = $logger;
 560         }
 561
 562         public function getServerInfo() {
 563                 return $this->getServerVersion();
 564         }
 565
 566         public function bufferResults( $buffer = null ) {
 567                 $res = !$this->getFlag( self::DBO_NOBUFFER );
 568                 if ( $buffer !== null ) {
 569                         $buffer
 570                                 ? $this->clearFlag( self::DBO_NOBUFFER )
 571                                 : $this->setFlag( self::DBO_NOBUFFER );
 572                 }
 573
 574                 return $res;
 575         }
 576
 577         public function trxLevel() {
 578                 return $this->trxLevel;
 579         }
 580
 581         public function trxTimestamp() {
 582                 return $this->trxLevel ? $this->trxTimestamp : null;
 583         }
 584
 585         /**
 586          * @return int One of the STATUS_TRX_* class constants
 587          * @since 1.31
 588          */
 589         public function trxStatus() {
 590                 return $this->trxStatus;
 591         }
 592
 593         public function tablePrefix( $prefix = null ) {
 594                 $old = $this->tablePrefix;
 595                 if ( $prefix !== null ) {
 596                         $this->tablePrefix = $prefix;
 597                         $this->currentDomain = ( $this->dbName != '' )
 598                                 ? new DatabaseDomain( $this->dbName, null, $this->tablePrefix )
 599                                 : DatabaseDomain::newUnspecified();
 600                 }
 601
 602                 return $old;
 603         }
 604
 605         public function dbSchema( $schema = null ) {
 606                 $old = $this->schema;
 607                 if ( $schema !== null ) {
 608                         $this->schema = $schema;
 609                 }
 610
 611                 return $old;
 612         }
 613
 614         public function getLBInfo( $name = null ) {
 615                 if ( is_null( $name ) ) {
 616                         return $this->lbInfo;
 617                 } else {
 618                         if ( array_key_exists( $name, $this->lbInfo ) ) {
 619                                 return $this->lbInfo[$name];
 620                         } else {
 621                                 return null;
 622                         }
 623                 }
 624         }
 625
 626         public function setLBInfo( $name, $value = null ) {
 627                 if ( is_null( $value ) ) {
 628                         $this->lbInfo = $name;
 629                 } else {
 630                         $this->lbInfo[$name] = $value;
 631                 }
 632         }
 633
 634         public function setLazyMasterHandle( IDatabase $conn ) {
 635                 $this->lazyMasterHandle = $conn;
 636         }
 637
 638         /**
 639          * @return IDatabase|null
 640          * @see setLazyMasterHandle()
 641          * @since 1.27
 642          */
 643         protected function getLazyMasterHandle() {
 644                 return $this->lazyMasterHandle;
 645         }
 646
 647         public function implicitGroupby() {
 648                 return true;
 649         }
 650
 651         public function implicitOrderby() {
 652                 return true;
 653         }
 654
 655         public function lastQuery() {
 656                 return $this->lastQuery;
 657         }
 658
 659         public function doneWrites() {
 660                 return (bool)$this->lastWriteTime;
 661         }
 662
 663         public function lastDoneWrites() {
 664                 return $this->lastWriteTime ?: false;
 665         }
 666
 667         public function writesPending() {
 668                 return $this->trxLevel && $this->trxDoneWrites;
 669         }
 670
 671         public function writesOrCallbacksPending() {
 672                 return $this->trxLevel && (
 673                         $this->trxDoneWrites ||
 674                         $this->trxIdleCallbacks ||
 675                         $this->trxPreCommitCallbacks ||
 676                         $this->trxEndCallbacks
 677                 );
 678         }
 679
 680         /**
 681          * @return string|null
 682          */
 683         final protected function getTransactionRoundId() {
 684                 // If transaction round participation is enabled, see if one is active
 685                 if ( $this->getFlag( self::DBO_TRX ) ) {
 686                         $id = $this->getLBInfo( 'trxRoundId' );
 687
 688                         return is_string( $id ) ? $id : null;
 689                 }
 690
 691                 return null;
 692         }
 693
 694         public function pendingWriteQueryDuration( $type = self::ESTIMATE_TOTAL ) {
 695                 if ( !$this->trxLevel ) {
 696                         return false;
 697                 } elseif ( !$this->trxDoneWrites ) {
 698                         return 0.0;
 699                 }
 700
 701                 switch ( $type ) {
 702                         case self::ESTIMATE_DB_APPLY:
 703                                 $this->ping( $rtt );
 704                                 $rttAdjTotal = $this->trxWriteAdjQueryCount * $rtt;
 705                                 $applyTime = max( $this->trxWriteAdjDuration - $rttAdjTotal, 0 );
 706                                 // For omitted queries, make them count as something at least
 707                                 $omitted = $this->trxWriteQueryCount - $this->trxWriteAdjQueryCount;
 708                                 $applyTime += self::TINY_WRITE_SEC * $omitted;
 709
 710                                 return $applyTime;
 711                         default: // everything
 712                                 return $this->trxWriteDuration;
 713                 }
 714         }
 715
 716         public function pendingWriteCallers() {
 717                 return $this->trxLevel ? $this->trxWriteCallers : [];
 718         }
 719
 720         public function pendingWriteRowsAffected() {
 721                 return $this->trxWriteAffectedRows;
 722         }
 723
 724         /**
 725          * Get the list of method names that have pending write queries or callbacks
 726          * for this transaction
 727          *
 728          * @return array
 729          */
 730         protected function pendingWriteAndCallbackCallers() {
 731                 if ( !$this->trxLevel ) {
 732                         return [];
 733                 }
 734
 735                 $fnames = $this->trxWriteCallers;
 736                 foreach ( [
 737                         $this->trxIdleCallbacks,
 738                         $this->trxPreCommitCallbacks,
 739                         $this->trxEndCallbacks
 740                 ] as $callbacks ) {
 741                         foreach ( $callbacks as $callback ) {
 742                                 $fnames[] = $callback[1];
 743                         }
 744                 }
 745
 746                 return $fnames;
 747         }
 748
 749         /**
 750          * @return string
 751          */
 752         private function flatAtomicSectionList() {
 753                 return array_reduce( $this->trxAtomicLevels, function ( $accum, $v ) {
 754                         return $accum === null ? $v[0] : "$accum, " . $v[0];
 755                 } );
 756         }
 757
 758         public function isOpen() {
 759                 return $this->opened;
 760         }
 761
 762         public function setFlag( $flag, $remember = self::REMEMBER_NOTHING ) {
 763                 if ( ( $flag & self::DBO_IGNORE ) ) {
 764                         throw new UnexpectedValueException( "Modifying DBO_IGNORE is not allowed." );
 765                 }
 766
 767                 if ( $remember === self::REMEMBER_PRIOR ) {
 768                         array_push( $this->priorFlags, $this->flags );
 769                 }
 770                 $this->flags |= $flag;
 771         }
 772
 773         public function clearFlag( $flag, $remember = self::REMEMBER_NOTHING ) {
 774                 if ( ( $flag & self::DBO_IGNORE ) ) {
 775                         throw new UnexpectedValueException( "Modifying DBO_IGNORE is not allowed." );
 776                 }
 777
 778                 if ( $remember === self::REMEMBER_PRIOR ) {
 779                         array_push( $this->priorFlags, $this->flags );
 780                 }
 781                 $this->flags &= ~$flag;
 782         }
 783
 784         public function restoreFlags( $state = self::RESTORE_PRIOR ) {
 785                 if ( !$this->priorFlags ) {
 786                         return;
 787                 }
 788
 789                 if ( $state === self::RESTORE_INITIAL ) {
 790                         $this->flags = reset( $this->priorFlags );
 791                         $this->priorFlags = [];
 792                 } else {
 793                         $this->flags = array_pop( $this->priorFlags );
 794                 }
 795         }
 796
 797         public function getFlag( $flag ) {
 798                 return !!( $this->flags & $flag );
 799         }
 800
 801         /**
 802          * @param string $name Class field name
 803          * @return mixed
 804          * @deprecated Since 1.28
 805          */
 806         public function getProperty( $name ) {
 807                 return $this->$name;
 808         }
 809
 810         public function getDomainID() {
 811                 return $this->currentDomain->getId();
 812         }
 813
 814         final public function getWikiID() {
 815                 return $this->getDomainID();
 816         }
 817
 818         /**
 819          * Get information about an index into an object
 820          * @param string $table Table name
 821          * @param string $index Index name
 822          * @param string $fname Calling function name
 823          * @return mixed Database-specific index description class or false if the index does not exist
 824          */
 825         abstract function indexInfo( $table, $index, $fname = __METHOD__ );
 826
 827         /**
 828          * Wrapper for addslashes()
 829          *
 830          * @param string $s String to be slashed.
 831          * @return string Slashed string.
 832          */
 833         abstract function strencode( $s );
 834
 835         /**
 836          * Set a custom error handler for logging errors during database connection
 837          */
 838         protected function installErrorHandler() {
 839                 $this->phpError = false;
 840                 $this->htmlErrors = ini_set( 'html_errors', '0' );
 841                 set_error_handler( [ $this, 'connectionErrorLogger' ] );
 842         }
 843
 844         /**
 845          * Restore the previous error handler and return the last PHP error for this DB
 846          *
 847          * @return bool|string
 848          */
 849         protected function restoreErrorHandler() {
 850                 restore_error_handler();
 851                 if ( $this->htmlErrors !== false ) {
 852                         ini_set( 'html_errors', $this->htmlErrors );
 853                 }
 854
 855                 return $this->getLastPHPError();
 856         }
 857
 858         /**
 859          * @return string|bool Last PHP error for this DB (typically connection errors)
 860          */
 861         protected function getLastPHPError() {
 862                 if ( $this->phpError ) {
 863                         $error = preg_replace( '!\[<a.*</a>\]!', '', $this->phpError );
 864                         $error = preg_replace( '!^.*?:\s?(.*)$!', '$1', $error );
 865
 866                         return $error;
 867                 }
 868
 869                 return false;
 870         }
 871
 872         /**
 873          * Error handler for logging errors during database connection
 874          * This method should not be used outside of Database classes
 875          *
 876          * @param int $errno
 877          * @param string $errstr
 878          */
 879         public function connectionErrorLogger( $errno, $errstr ) {
 880                 $this->phpError = $errstr;
 881         }
 882
 883         /**
 884          * Create a log context to pass to PSR-3 logger functions.
 885          *
 886          * @param array $extras Additional data to add to context
 887          * @return array
 888          */
 889         protected function getLogContext( array $extras = [] ) {
 890                 return array_merge(
 891                         [
 892                                 'db_server' => $this->server,
 893                                 'db_name' => $this->dbName,
 894                                 'db_user' => $this->user,
 895                         ],
 896                         $extras
 897                 );
 898         }
 899
 900         final public function close() {
 901                 $exception = null; // error to throw after disconnecting
 902
 903                 if ( $this->conn ) {
 904                         // Resolve any dangling transaction first
 905                         if ( $this->trxLevel ) {
 906                                 if ( $this->trxAtomicLevels ) {
 907                                         // Cannot let incomplete atomic sections be committed
 908                                         $levels = $this->flatAtomicSectionList();
 909                                         $exception = new DBUnexpectedError(
 910                                                 $this,
 911                                                 __METHOD__ . ": atomic sections $levels are still open."
 912                                         );
 913                                 } elseif ( $this->trxAutomatic ) {
 914                                         // Only the connection manager can commit non-empty DBO_TRX transactions
 915                                         if ( $this->writesOrCallbacksPending() ) {
 916                                                 $exception = new DBUnexpectedError(
 917                                                         $this,
 918                                                         __METHOD__ .
 919                                                         ": mass commit/rollback of peer transaction required (DBO_TRX set)."
 920                                                 );
 921                                         }
 922                                 } elseif ( $this->trxLevel ) {
 923                                         // Commit explicit transactions as if this was commit()
 924                                         $this->queryLogger->warning(
 925                                                 __METHOD__ . ": writes or callbacks still pending.",
 926                                                 [ 'trace' => ( new RuntimeException() )->getTraceAsString() ]
 927                                         );
 928                                 }
 929
 930                                 if ( $this->trxEndCallbacksSuppressed ) {
 931                                         $exception = $exception ?: new DBUnexpectedError(
 932                                                 $this,
 933                                                 __METHOD__ . ': callbacks are suppressed; cannot properly commit.'
 934                                         );
 935                                 }
 936
 937                                 // Commit or rollback the changes and run any callbacks as needed
 938                                 if ( $this->trxStatus === self::STATUS_TRX_OK && !$exception ) {
 939                                         $this->commit(
 940                                                 __METHOD__,
 941                                                 $this->trxAutomatic ? self::FLUSHING_INTERNAL : self::FLUSHING_ONE
 942                                         );
 943                                 } else {
 944                                         $this->rollback( __METHOD__, self::FLUSHING_INTERNAL );
 945                                 }
 946                         }
 947
 948                         // Close the actual connection in the binding handle
 949                         $closed = $this->closeConnection();
 950                         $this->conn = false;
 951                 } else {
 952                         $closed = true; // already closed; nothing to do
 953                 }
 954
 955                 $this->opened = false;
 956
 957                 // Throw any unexpected errors after having disconnected
 958                 if ( $exception instanceof Exception ) {
 959                         throw $exception;
 960                 }
 961
 962                 // Sanity check that no callbacks are dangling
 963                 if (
 964                         $this->trxIdleCallbacks || $this->trxPreCommitCallbacks || $this->trxEndCallbacks
 965                 ) {
 966                         throw new RuntimeException(
 967                                 "Transaction callbacks are still pending:\n" .
 968                                 implode( ', ', $this->pendingWriteAndCallbackCallers() )
 969                         );
 970                 }
 971
 972                 return $closed;
 973         }
 974
 975         /**
 976          * Make sure isOpen() returns true as a sanity check
 977          *
 978          * @throws DBUnexpectedError
 979          */
 980         protected function assertOpen() {
 981                 if ( !$this->isOpen() ) {
 982                         throw new DBUnexpectedError( $this, "DB connection was already closed." );
 983                 }
 984         }
 985
 986         /**
 987          * Closes underlying database connection
 988          * @since 1.20
 989          * @return bool Whether connection was closed successfully
 990          */
 991         abstract protected function closeConnection();
 992
 993         /**
 994          * @param string $error Fallback error message, used if none is given by DB
 995          * @throws DBConnectionError
 996          */
 997         public function reportConnectionError( $error = 'Unknown error' ) {
 998                 $myError = $this->lastError();
 999                 if ( $myError ) {
1000                         $error = $myError;
1001                 }
1002
1003                 # New method
1004                 throw new DBConnectionError( $this, $error );
1005         }
1006
1007         /**
1008          * Run a query and return a DBMS-dependent wrapper (that has all IResultWrapper methods)
1009          *
1010          * This might return things, such as mysqli_result, that do not formally implement
1011          * IResultWrapper, but nonetheless implement all of its methods correctly
1012          *
1013          * @param string $sql SQL query.
1014          * @return IResultWrapper|bool Iterator to feed to fetchObject/fetchRow; false on failure
1015          */
1016         abstract protected function doQuery( $sql );
1017
1018         /**
1019          * Determine whether a query writes to the DB.
1020          * Should return true if unsure.
1021          *
1022          * @param string $sql
1023          * @return bool
1024          */
1025         protected function isWriteQuery( $sql ) {
1026                 return !preg_match(
1027                         '/^(?:SELECT|BEGIN|ROLLBACK|COMMIT|SET|SHOW|EXPLAIN|\(SELECT)\b/i', $sql );
1028         }
1029
1030         /**
1031          * @param string $sql
1032          * @return string|null
1033          */
1034         protected function getQueryVerb( $sql ) {
1035                 return preg_match( '/^\s*([a-z]+)/i', $sql, $m ) ? strtoupper( $m[1] ) : null;
1036         }
1037
1038         /**
1039          * Determine whether a SQL statement is sensitive to isolation level.
1040          * A SQL statement is considered transactable if its result could vary
1041          * depending on the transaction isolation level. Operational commands
1042          * such as 'SET' and 'SHOW' are not considered to be transactable.
1043          *
1044          * @param string $sql
1045          * @return bool
1046          */
1047         protected function isTransactableQuery( $sql ) {
1048                 return !in_array(
1049                         $this->getQueryVerb( $sql ),
1050                         [ 'BEGIN', 'COMMIT', 'ROLLBACK', 'SHOW', 'SET', 'CREATE', 'ALTER' ],
1051                         true
1052                 );
1053         }
1054
1055         /**
1056          * @param string $sql A SQL query
1057          * @return bool Whether $sql is SQL for TEMPORARY table operation
1058          */
1059         protected function registerTempTableOperation( $sql ) {
1060                 if ( preg_match(
1061                         '/^CREATE\s+TEMPORARY\s+TABLE\s+(?:IF\s+NOT\s+EXISTS\s+)?[`"\']?(\w+)[`"\']?/i',
1062                         $sql,
1063                         $matches
1064                 ) ) {
1065                         $this->sessionTempTables[$matches[1]] = 1;
1066
1067                         return true;
1068                 } elseif ( preg_match(
1069                         '/^DROP\s+(?:TEMPORARY\s+)?TABLE\s+(?:IF\s+EXISTS\s+)?[`"\']?(\w+)[`"\']?/i',
1070                         $sql,
1071                         $matches
1072                 ) ) {
1073                         $isTemp = isset( $this->sessionTempTables[$matches[1]] );
1074                         unset( $this->sessionTempTables[$matches[1]] );
1075
1076                         return $isTemp;
1077                 } elseif ( preg_match(
1078                         '/^TRUNCATE\s+(?:TEMPORARY\s+)?TABLE\s+(?:IF\s+EXISTS\s+)?[`"\']?(\w+)[`"\']?/i',
1079                         $sql,
1080                         $matches
1081                 ) ) {
1082                         return isset( $this->sessionTempTables[$matches[1]] );
1083                 } elseif ( preg_match(
1084                         '/^(?:INSERT\s+(?:\w+\s+)?INTO|UPDATE|DELETE\s+FROM)\s+[`"\']?(\w+)[`"\']?/i',
1085                         $sql,
1086                         $matches
1087                 ) ) {
1088                         return isset( $this->sessionTempTables[$matches[1]] );
1089                 }
1090
1091                 return false;
1092         }
1093
1094         public function query( $sql, $fname = __METHOD__, $tempIgnore = false ) {
1095                 $this->assertTransactionStatus( $sql, $fname );
1096
1097                 # Avoid fatals if close() was called
1098                 $this->assertOpen();
1099
1100                 $priorWritesPending = $this->writesOrCallbacksPending();
1101                 $this->lastQuery = $sql;
1102
1103                 $isWrite = $this->isWriteQuery( $sql );
1104                 if ( $isWrite ) {
1105                         $isNonTempWrite = !$this->registerTempTableOperation( $sql );
1106                 } else {
1107                         $isNonTempWrite = false;
1108                 }
1109
1110                 if ( $isWrite ) {
1111                         if ( $this->getLBInfo( 'replica' ) === true ) {
1112                                 throw new DBError(
1113                                         $this,
1114                                         'Write operations are not allowed on replica database connections.'
1115                                 );
1116                         }
1117                         # In theory, non-persistent writes are allowed in read-only mode, but due to things
1118                         # like https://bugs.mysql.com/bug.php?id=33669 that might not work anyway...
1119                         $reason = $this->getReadOnlyReason();
1120                         if ( $reason !== false ) {
1121                                 throw new DBReadOnlyError( $this, "Database is read-only: $reason" );
1122                         }
1123                         # Set a flag indicating that writes have been done
1124                         $this->lastWriteTime = microtime( true );
1125                 }
1126
1127                 # Add trace comment to the begin of the sql string, right after the operator.
1128                 # Or, for one-word queries (like "BEGIN" or COMMIT") add it to the end (T44598)
1129                 $commentedSql = preg_replace( '/\s|$/', " /* $fname {$this->agent} */ ", $sql, 1 );
1130
1131                 # Start implicit transactions that wrap the request if DBO_TRX is enabled
1132                 if ( !$this->trxLevel && $this->getFlag( self::DBO_TRX )
1133                         && $this->isTransactableQuery( $sql )
1134                 ) {
1135                         $this->begin( __METHOD__ . " ($fname)", self::TRANSACTION_INTERNAL );
1136                         $this->trxAutomatic = true;
1137                 }
1138
1139                 # Keep track of whether the transaction has write queries pending
1140                 if ( $this->trxLevel && !$this->trxDoneWrites && $isWrite ) {
1141                         $this->trxDoneWrites = true;
1142                         $this->trxProfiler->transactionWritingIn(
1143                                 $this->server, $this->dbName, $this->trxShortId );
1144                 }
1145
1146                 if ( $this->getFlag( self::DBO_DEBUG ) ) {
1147                         $this->queryLogger->debug( "{$this->dbName} {$commentedSql}" );
1148                 }
1149
1150                 # Send the query to the server and fetch any corresponding errors
1151                 $ret = $this->doProfiledQuery( $sql, $commentedSql, $isNonTempWrite, $fname );
1152                 $lastError = $this->lastError();
1153                 $lastErrno = $this->lastErrno();
1154
1155                 # Try reconnecting if the connection was lost
1156                 if ( $ret === false && $this->wasConnectionLoss() ) {
1157                         # Check if any meaningful session state was lost
1158                         $recoverable = $this->canRecoverFromDisconnect( $sql, $priorWritesPending );
1159                         # Update session state tracking and try to restore the connection
1160                         $reconnected = $this->replaceLostConnection( __METHOD__ );
1161                         # Silently resend the query to the server if it is safe and possible
1162                         if ( $reconnected && $recoverable ) {
1163                                 $ret = $this->doProfiledQuery( $sql, $commentedSql, $isNonTempWrite, $fname );
1164                                 $lastError = $this->lastError();
1165                                 $lastErrno = $this->lastErrno();
1166
1167                                 if ( $ret === false && $this->wasConnectionLoss() ) {
1168                                         # Query probably causes disconnects; reconnect and do not re-run it
1169                                         $this->replaceLostConnection( __METHOD__ );
1170                                 }
1171                         }
1172                 }
1173
1174                 if ( $ret === false ) {
1175                         if ( $this->trxLevel ) {
1176                                 if ( !$this->wasKnownStatementRollbackError() ) {
1177                                         # Either the query was aborted or all queries after BEGIN where aborted.
1178                                         if ( $this->explicitTrxActive() || $priorWritesPending ) {
1179                                                 # In the first case, the only options going forward are (a) ROLLBACK, or
1180                                                 # (b) ROLLBACK TO SAVEPOINT (if one was set). If the later case, the only
1181                                                 # option is ROLLBACK, since the snapshots would have been released.
1182                                                 $this->trxStatus = self::STATUS_TRX_ERROR;
1183                                                 $this->trxStatusCause =
1184                                                         $this->makeQueryException( $lastError, $lastErrno, $sql, $fname );
1185                                                 $tempIgnore = false; // cannot recover
1186                                         } else {
1187                                                 # Nothing prior was there to lose from the transaction,
1188                                                 # so just roll it back.
1189                                                 $this->doRollback( __METHOD__ . " ($fname)" );
1190                                                 $this->trxStatus = self::STATUS_TRX_OK;
1191                                         }
1192                                         $this->trxStatusIgnoredCause = null;
1193                                 } else {
1194                                         # We're ignoring an error that caused just the current query to be aborted.
1195                                         # But log the cause so we can log a deprecation notice if a
1196                                         # caller actually does ignore it.
1197                                         $this->trxStatusIgnoredCause = [ $lastError, $lastErrno, $fname ];
1198                                 }
1199                         }
1200
1201                         $this->reportQueryError( $lastError, $lastErrno, $sql, $fname, $tempIgnore );
1202                 }
1203
1204                 return $this->resultObject( $ret );
1205         }
1206
1207         /**
1208          * Wrapper for query() that also handles profiling, logging, and affected row count updates
1209          *
1210          * @param string $sql Original SQL query
1211          * @param string $commentedSql SQL query with debugging/trace comment
1212          * @param bool $isWrite Whether the query is a (non-temporary) write operation
1213          * @param string $fname Name of the calling function
1214          * @return bool|ResultWrapper True for a successful write query, ResultWrapper
1215          *     object for a successful read query, or false on failure
1216          */
1217         private function doProfiledQuery( $sql, $commentedSql, $isWrite, $fname ) {
1218                 $isMaster = !is_null( $this->getLBInfo( 'master' ) );
1219                 # generalizeSQL() will probably cut down the query to reasonable
1220                 # logging size most of the time. The substr is really just a sanity check.
1221                 if ( $isMaster ) {
1222                         $queryProf = 'query-m: ' . substr( self::generalizeSQL( $sql ), 0, 255 );
1223                 } else {
1224                         $queryProf = 'query: ' . substr( self::generalizeSQL( $sql ), 0, 255 );
1225                 }
1226
1227                 # Include query transaction state
1228                 $queryProf .= $this->trxShortId ? " [TRX#{$this->trxShortId}]" : "";
1229
1230                 $startTime = microtime( true );
1231                 if ( $this->profiler ) {
1232                         call_user_func( [ $this->profiler, 'profileIn' ], $queryProf );
1233                 }
1234                 $this->affectedRowCount = null;
1235                 $ret = $this->doQuery( $commentedSql );
1236                 $this->affectedRowCount = $this->affectedRows();
1237                 if ( $this->profiler ) {
1238                         call_user_func( [ $this->profiler, 'profileOut' ], $queryProf );
1239                 }
1240                 $queryRuntime = max( microtime( true ) - $startTime, 0.0 );
1241
1242                 unset( $queryProfSection ); // profile out (if set)
1243
1244                 if ( $ret !== false ) {
1245                         $this->lastPing = $startTime;
1246                         if ( $isWrite && $this->trxLevel ) {
1247                                 $this->updateTrxWriteQueryTime( $sql, $queryRuntime, $this->affectedRows() );
1248                                 $this->trxWriteCallers[] = $fname;
1249                         }
1250                 }
1251
1252                 if ( $sql === self::PING_QUERY ) {
1253                         $this->rttEstimate = $queryRuntime;
1254                 }
1255
1256                 $this->trxProfiler->recordQueryCompletion(
1257                         $queryProf, $startTime, $isWrite, $this->affectedRows()
1258                 );
1259                 $this->queryLogger->debug( $sql, [
1260                         'method' => $fname,
1261                         'master' => $isMaster,
1262                         'runtime' => $queryRuntime,
1263                 ] );
1264
1265                 return $ret;
1266         }
1267
1268         /**
1269          * Update the estimated run-time of a query, not counting large row lock times
1270          *
1271          * LoadBalancer can be set to rollback transactions that will create huge replication
1272          * lag. It bases this estimate off of pendingWriteQueryDuration(). Certain simple
1273          * queries, like inserting a row can take a long time due to row locking. This method
1274          * uses some simple heuristics to discount those cases.
1275          *
1276          * @param string $sql A SQL write query
1277          * @param float $runtime Total runtime, including RTT
1278          * @param int $affected Affected row count
1279          */
1280         private function updateTrxWriteQueryTime( $sql, $runtime, $affected ) {
1281                 // Whether this is indicative of replica DB runtime (except for RBR or ws_repl)
1282                 $indicativeOfReplicaRuntime = true;
1283                 if ( $runtime > self::SLOW_WRITE_SEC ) {
1284                         $verb = $this->getQueryVerb( $sql );
1285                         // insert(), upsert(), replace() are fast unless bulky in size or blocked on locks
1286                         if ( $verb === 'INSERT' ) {
1287                                 $indicativeOfReplicaRuntime = $this->affectedRows() > self::SMALL_WRITE_ROWS;
1288                         } elseif ( $verb === 'REPLACE' ) {
1289                                 $indicativeOfReplicaRuntime = $this->affectedRows() > self::SMALL_WRITE_ROWS / 2;
1290                         }
1291                 }
1292
1293                 $this->trxWriteDuration += $runtime;
1294                 $this->trxWriteQueryCount += 1;
1295                 $this->trxWriteAffectedRows += $affected;
1296                 if ( $indicativeOfReplicaRuntime ) {
1297                         $this->trxWriteAdjDuration += $runtime;
1298                         $this->trxWriteAdjQueryCount += 1;
1299                 }
1300         }
1301
1302         /**
1303          * @param string $sql
1304          * @param string $fname
1305          * @throws DBTransactionStateError
1306          */
1307         private function assertTransactionStatus( $sql, $fname ) {
1308                 if ( $this->getQueryVerb( $sql ) === 'ROLLBACK' ) { // transaction/savepoint
1309                         return;
1310                 }
1311
1312                 if ( $this->trxStatus < self::STATUS_TRX_OK ) {
1313                         throw new DBTransactionStateError(
1314                                 $this,
1315                                 "Cannot execute query from $fname while transaction status is ERROR.",
1316                                 [],
1317                                 $this->trxStatusCause
1318                         );
1319                 } elseif ( $this->trxStatus === self::STATUS_TRX_OK && $this->trxStatusIgnoredCause ) {
1320                         list( $iLastError, $iLastErrno, $iFname ) = $this->trxStatusIgnoredCause;
1321                         call_user_func( $this->deprecationLogger,
1322                                 "Caller from $fname ignored an error originally raised from $iFname: " .
1323                                 "[$iLastErrno] $iLastError"
1324                         );
1325                         $this->trxStatusIgnoredCause = null;
1326                 }
1327         }
1328
1329         /**
1330          * Determine whether or not it is safe to retry queries after a database
1331          * connection is lost
1332          *
1333          * @param string $sql SQL query
1334          * @param bool $priorWritesPending Whether there is a transaction open with
1335          *     possible write queries or transaction pre-commit/idle callbacks
1336          *     waiting on it to finish.
1337          * @return bool True if it is safe to retry the query, false otherwise
1338          */
1339         private function canRecoverFromDisconnect( $sql, $priorWritesPending ) {
1340                 # Transaction dropped; this can mean lost writes, or REPEATABLE-READ snapshots.
1341                 # Dropped connections also mean that named locks are automatically released.
1342                 # Only allow error suppression in autocommit mode or when the lost transaction
1343                 # didn't matter anyway (aside from DBO_TRX snapshot loss).
1344                 if ( $this->namedLocksHeld ) {
1345                         return false; // possible critical section violation
1346                 } elseif ( $this->sessionTempTables ) {
1347                         return false; // tables might be queried latter
1348                 } elseif ( $sql === 'COMMIT' ) {
1349                         return !$priorWritesPending; // nothing written anyway? (T127428)
1350                 } elseif ( $sql === 'ROLLBACK' ) {
1351                         return true; // transaction lost...which is also what was requested :)
1352                 } elseif ( $this->explicitTrxActive() ) {
1353                         return false; // don't drop atomocity and explicit snapshots
1354                 } elseif ( $priorWritesPending ) {
1355                         return false; // prior writes lost from implicit transaction
1356                 }
1357
1358                 return true;
1359         }
1360
1361         /**
1362          * Clean things up after session (and thus transaction) loss
1363          */
1364         private function handleSessionLoss() {
1365                 // Clean up tracking of session-level things...
1366                 // https://dev.mysql.com/doc/refman/5.7/en/implicit-commit.html
1367                 // https://www.postgresql.org/docs/9.2/static/sql-createtable.html (ignoring ON COMMIT)
1368                 $this->sessionTempTables = [];
1369                 // https://dev.mysql.com/doc/refman/5.7/en/miscellaneous-functions.html#function_get-lock
1370                 // https://www.postgresql.org/docs/9.4/static/functions-admin.html#FUNCTIONS-ADVISORY-LOCKS
1371                 $this->namedLocksHeld = [];
1372                 // Session loss implies transaction loss
1373                 $this->handleTransactionLoss();
1374         }
1375
1376         /**
1377          * Clean things up after transaction loss
1378          */
1379         private function handleTransactionLoss() {
1380                 $this->trxLevel = 0;
1381                 $this->trxAtomicCounter = 0;
1382                 $this->trxIdleCallbacks = []; // T67263; transaction already lost
1383                 $this->trxPreCommitCallbacks = []; // T67263; transaction already lost
1384                 try {
1385                         // Handle callbacks in trxEndCallbacks, e.g. onTransactionResolution().
1386                         // If callback suppression is set then the array will remain unhandled.
1387                         $this->runOnTransactionIdleCallbacks( self::TRIGGER_ROLLBACK );
1388                 } catch ( Exception $ex ) {
1389                         // Already logged; move on...
1390                 }
1391                 try {
1392                         // Handle callbacks in trxRecurringCallbacks, e.g. setTransactionListener()
1393                         $this->runTransactionListenerCallbacks( self::TRIGGER_ROLLBACK );
1394                 } catch ( Exception $ex ) {
1395                         // Already logged; move on...
1396                 }
1397         }
1398
1399         /**
1400          * Checks whether the cause of the error is detected to be a timeout.
1401          *
1402          * It returns false by default, and not all engines support detecting this yet.
1403          * If this returns false, it will be treated as a generic query error.
1404          *
1405          * @param string $error Error text
1406          * @param int $errno Error number
1407          * @return bool
1408          */
1409         protected function wasQueryTimeout( $error, $errno ) {
1410                 return false;
1411         }
1412
1413         /**
1414          * Report a query error. Log the error, and if neither the object ignore
1415          * flag nor the $tempIgnore flag is set, throw a DBQueryError.
1416          *
1417          * @param string $error
1418          * @param int $errno
1419          * @param string $sql
1420          * @param string $fname
1421          * @param bool $tempIgnore
1422          * @throws DBQueryError
1423          */
1424         public function reportQueryError( $error, $errno, $sql, $fname, $tempIgnore = false ) {
1425                 if ( $tempIgnore ) {
1426                         $this->queryLogger->debug( "SQL ERROR (ignored): $error\n" );
1427                 } else {
1428                         $exception = $this->makeQueryException( $error, $errno, $sql, $fname );
1429
1430                         throw $exception;
1431                 }
1432         }
1433
1434         /**
1435          * @param string $error
1436          * @param string|int $errno
1437          * @param string $sql
1438          * @param string $fname
1439          * @return DBError
1440          */
1441         private function makeQueryException( $error, $errno, $sql, $fname ) {
1442                 $sql1line = mb_substr( str_replace( "\n", "\\n", $sql ), 0, 5 * 1024 );
1443                 $this->queryLogger->error(
1444                         "{fname}\t{db_server}\t{errno}\t{error}\t{sql1line}",
1445                         $this->getLogContext( [
1446                                 'method' => __METHOD__,
1447                                 'errno' => $errno,
1448                                 'error' => $error,
1449                                 'sql1line' => $sql1line,
1450                                 'fname' => $fname,
1451                         ] )
1452                 );
1453                 $this->queryLogger->debug( "SQL ERROR: " . $error . "\n" );
1454                 $wasQueryTimeout = $this->wasQueryTimeout( $error, $errno );
1455                 if ( $wasQueryTimeout ) {
1456                         $e = new DBQueryTimeoutError( $this, $error, $errno, $sql, $fname );
1457                 } else {
1458                         $e = new DBQueryError( $this, $error, $errno, $sql, $fname );
1459                 }
1460
1461                 return $e;
1462         }
1463
1464         public function freeResult( $res ) {
1465         }
1466
1467         public function selectField(
1468                 $table, $var, $cond = '', $fname = __METHOD__, $options = [], $join_conds = []
1469         ) {
1470                 if ( $var === '*' ) { // sanity
1471                         throw new DBUnexpectedError( $this, "Cannot use a * field: got '$var'" );
1472                 }
1473
1474                 if ( !is_array( $options ) ) {
1475                         $options = [ $options ];
1476                 }
1477
1478                 $options['LIMIT'] = 1;
1479
1480                 $res = $this->select( $table, $var, $cond, $fname, $options, $join_conds );
1481                 if ( $res === false || !$this->numRows( $res ) ) {
1482                         return false;
1483                 }
1484
1485                 $row = $this->fetchRow( $res );
1486
1487                 if ( $row !== false ) {
1488                         return reset( $row );
1489                 } else {
1490                         return false;
1491                 }
1492         }
1493
1494         public function selectFieldValues(
1495                 $table, $var, $cond = '', $fname = __METHOD__, $options = [], $join_conds = []
1496         ) {
1497                 if ( $var === '*' ) { // sanity
1498                         throw new DBUnexpectedError( $this, "Cannot use a * field" );
1499                 } elseif ( !is_string( $var ) ) { // sanity
1500                         throw new DBUnexpectedError( $this, "Cannot use an array of fields" );
1501                 }
1502
1503                 if ( !is_array( $options ) ) {
1504                         $options = [ $options ];
1505                 }
1506
1507                 $res = $this->select( $table, $var, $cond, $fname, $options, $join_conds );
1508                 if ( $res === false ) {
1509                         return false;
1510                 }
1511
1512                 $values = [];
1513                 foreach ( $res as $row ) {
1514                         $values[] = $row->$var;
1515                 }
1516
1517                 return $values;
1518         }
1519
1520         /**
1521          * Returns an optional USE INDEX clause to go after the table, and a
1522          * string to go at the end of the query.
1523          *
1524          * @param array $options Associative array of options to be turned into
1525          *   an SQL query, valid keys are listed in the function.
1526          * @return array
1527          * @see Database::select()
1528          */
1529         protected function makeSelectOptions( $options ) {
1530                 $preLimitTail = $postLimitTail = '';
1531                 $startOpts = '';
1532
1533                 $noKeyOptions = [];
1534
1535                 foreach ( $options as $key => $option ) {
1536                         if ( is_numeric( $key ) ) {
1537                                 $noKeyOptions[$option] = true;
1538                         }
1539                 }
1540
1541                 $preLimitTail .= $this->makeGroupByWithHaving( $options );
1542
1543                 $preLimitTail .= $this->makeOrderBy( $options );
1544
1545                 if ( isset( $noKeyOptions['FOR UPDATE'] ) ) {
1546                         $postLimitTail .= ' FOR UPDATE';
1547                 }
1548
1549                 if ( isset( $noKeyOptions['LOCK IN SHARE MODE'] ) ) {
1550                         $postLimitTail .= ' LOCK IN SHARE MODE';
1551                 }
1552
1553                 if ( isset( $noKeyOptions['DISTINCT'] ) || isset( $noKeyOptions['DISTINCTROW'] ) ) {
1554                         $startOpts .= 'DISTINCT';
1555                 }
1556
1557                 # Various MySQL extensions
1558                 if ( isset( $noKeyOptions['STRAIGHT_JOIN'] ) ) {
1559                         $startOpts .= ' /*! STRAIGHT_JOIN */';
1560                 }
1561
1562                 if ( isset( $noKeyOptions['HIGH_PRIORITY'] ) ) {
1563                         $startOpts .= ' HIGH_PRIORITY';
1564                 }
1565
1566                 if ( isset( $noKeyOptions['SQL_BIG_RESULT'] ) ) {
1567                         $startOpts .= ' SQL_BIG_RESULT';
1568                 }
1569
1570                 if ( isset( $noKeyOptions['SQL_BUFFER_RESULT'] ) ) {
1571                         $startOpts .= ' SQL_BUFFER_RESULT';
1572                 }
1573
1574                 if ( isset( $noKeyOptions['SQL_SMALL_RESULT'] ) ) {
1575                         $startOpts .= ' SQL_SMALL_RESULT';
1576                 }
1577
1578                 if ( isset( $noKeyOptions['SQL_CALC_FOUND_ROWS'] ) ) {
1579                         $startOpts .= ' SQL_CALC_FOUND_ROWS';
1580                 }
1581
1582                 if ( isset( $noKeyOptions['SQL_CACHE'] ) ) {
1583                         $startOpts .= ' SQL_CACHE';
1584                 }
1585
1586                 if ( isset( $noKeyOptions['SQL_NO_CACHE'] ) ) {
1587                         $startOpts .= ' SQL_NO_CACHE';
1588                 }
1589
1590                 if ( isset( $options['USE INDEX'] ) && is_string( $options['USE INDEX'] ) ) {
1591                         $useIndex = $this->useIndexClause( $options['USE INDEX'] );
1592                 } else {
1593                         $useIndex = '';
1594                 }
1595                 if ( isset( $options['IGNORE INDEX'] ) && is_string( $options['IGNORE INDEX'] ) ) {
1596                         $ignoreIndex = $this->ignoreIndexClause( $options['IGNORE INDEX'] );
1597                 } else {
1598                         $ignoreIndex = '';
1599                 }
1600
1601                 return [ $startOpts, $useIndex, $preLimitTail, $postLimitTail, $ignoreIndex ];
1602         }
1603
1604         /**
1605          * Returns an optional GROUP BY with an optional HAVING
1606          *
1607          * @param array $options Associative array of options
1608          * @return string
1609          * @see Database::select()
1610          * @since 1.21
1611          */
1612         protected function makeGroupByWithHaving( $options ) {
1613                 $sql = '';
1614                 if ( isset( $options['GROUP BY'] ) ) {
1615                         $gb = is_array( $options['GROUP BY'] )
1616                                 ? implode( ',', $options['GROUP BY'] )
1617                                 : $options['GROUP BY'];
1618                         $sql .= ' GROUP BY ' . $gb;
1619                 }
1620                 if ( isset( $options['HAVING'] ) ) {
1621                         $having = is_array( $options['HAVING'] )
1622                                 ? $this->makeList( $options['HAVING'], self::LIST_AND )
1623                                 : $options['HAVING'];
1624                         $sql .= ' HAVING ' . $having;
1625                 }
1626
1627                 return $sql;
1628         }
1629
1630         /**
1631          * Returns an optional ORDER BY
1632          *
1633          * @param array $options Associative array of options
1634          * @return string
1635          * @see Database::select()
1636          * @since 1.21
1637          */
1638         protected function makeOrderBy( $options ) {
1639                 if ( isset( $options['ORDER BY'] ) ) {
1640                         $ob = is_array( $options['ORDER BY'] )
1641                                 ? implode( ',', $options['ORDER BY'] )
1642                                 : $options['ORDER BY'];
1643
1644                         return ' ORDER BY ' . $ob;
1645                 }
1646
1647                 return '';
1648         }
1649
1650         public function select( $table, $vars, $conds = '', $fname = __METHOD__,
1651                 $options = [], $join_conds = [] ) {
1652                 $sql = $this->selectSQLText( $table, $vars, $conds, $fname, $options, $join_conds );
1653
1654                 return $this->query( $sql, $fname );
1655         }
1656
1657         public function selectSQLText( $table, $vars, $conds = '', $fname = __METHOD__,
1658                 $options = [], $join_conds = []
1659         ) {
1660                 if ( is_array( $vars ) ) {
1661                         $vars = implode( ',', $this->fieldNamesWithAlias( $vars ) );
1662                 }
1663
1664                 $options = (array)$options;
1665                 $useIndexes = ( isset( $options['USE INDEX'] ) && is_array( $options['USE INDEX'] ) )
1666                         ? $options['USE INDEX']
1667                         : [];
1668                 $ignoreIndexes = (
1669                         isset( $options['IGNORE INDEX'] ) &&
1670                         is_array( $options['IGNORE INDEX'] )
1671                 )
1672                         ? $options['IGNORE INDEX']
1673                         : [];
1674
1675                 if ( is_array( $table ) ) {
1676                         $from = ' FROM ' .
1677                                 $this->tableNamesWithIndexClauseOrJOIN(
1678                                         $table, $useIndexes, $ignoreIndexes, $join_conds );
1679                 } elseif ( $table != '' ) {
1680                         $from = ' FROM ' .
1681                                 $this->tableNamesWithIndexClauseOrJOIN(
1682                                         [ $table ], $useIndexes, $ignoreIndexes, [] );
1683                 } else {
1684                         $from = '';
1685                 }
1686
1687                 list( $startOpts, $useIndex, $preLimitTail, $postLimitTail, $ignoreIndex ) =
1688                         $this->makeSelectOptions( $options );
1689
1690                 if ( is_array( $conds ) ) {
1691                         $conds = $this->makeList( $conds, self::LIST_AND );
1692                 }
1693
1694                 if ( $conds === null || $conds === false ) {
1695                         $this->queryLogger->warning(
1696                                 __METHOD__
1697                                 . ' called from '
1698                                 . $fname
1699                                 . ' with incorrect parameters: $conds must be a string or an array'
1700                         );
1701                         $conds = '';
1702                 }
1703
1704                 if ( $conds === '' ) {
1705                         $sql = "SELECT $startOpts $vars $from $useIndex $ignoreIndex $preLimitTail";
1706                 } elseif ( is_string( $conds ) ) {
1707                         $sql = "SELECT $startOpts $vars $from $useIndex $ignoreIndex " .
1708                                 "WHERE $conds $preLimitTail";
1709                 } else {
1710                         throw new DBUnexpectedError( $this, __METHOD__ . ' called with incorrect parameters' );
1711                 }
1712
1713                 if ( isset( $options['LIMIT'] ) ) {
1714                         $sql = $this->limitResult( $sql, $options['LIMIT'],
1715                                 isset( $options['OFFSET'] ) ? $options['OFFSET'] : false );
1716                 }
1717                 $sql = "$sql $postLimitTail";
1718
1719                 if ( isset( $options['EXPLAIN'] ) ) {
1720                         $sql = 'EXPLAIN ' . $sql;
1721                 }
1722
1723                 return $sql;
1724         }
1725
1726         public function selectRow( $table, $vars, $conds, $fname = __METHOD__,
1727                 $options = [], $join_conds = []
1728         ) {
1729                 $options = (array)$options;
1730                 $options['LIMIT'] = 1;
1731                 $res = $this->select( $table, $vars, $conds, $fname, $options, $join_conds );
1732
1733                 if ( $res === false ) {
1734                         return false;
1735                 }
1736
1737                 if ( !$this->numRows( $res ) ) {
1738                         return false;
1739                 }
1740
1741                 $obj = $this->fetchObject( $res );
1742
1743                 return $obj;
1744         }
1745
1746         public function estimateRowCount(
1747                 $table, $var = '*', $conds = '', $fname = __METHOD__, $options = [], $join_conds = []
1748         ) {
1749                 $conds = $this->normalizeConditions( $conds, $fname );
1750                 $column = $this->extractSingleFieldFromList( $var );
1751                 if ( is_string( $column ) && !in_array( $column, [ '*', '1' ] ) ) {
1752                         $conds[] = "$column IS NOT NULL";
1753                 }
1754
1755                 $res = $this->select(
1756                         $table, [ 'rowcount' => 'COUNT(*)' ], $conds, $fname, $options, $join_conds
1757                 );
1758                 $row = $res ? $this->fetchRow( $res ) : [];
1759
1760                 return isset( $row['rowcount'] ) ? (int)$row['rowcount'] : 0;
1761         }
1762
1763         public function selectRowCount(
1764                 $tables, $var = '*', $conds = '', $fname = __METHOD__, $options = [], $join_conds = []
1765         ) {
1766                 $conds = $this->normalizeConditions( $conds, $fname );
1767                 $column = $this->extractSingleFieldFromList( $var );
1768                 if ( is_string( $column ) && !in_array( $column, [ '*', '1' ] ) ) {
1769                         $conds[] = "$column IS NOT NULL";
1770                 }
1771
1772                 $res = $this->select(
1773                         [
1774                                 'tmp_count' => $this->buildSelectSubquery(
1775                                         $tables,
1776                                         '1',
1777                                         $conds,
1778                                         $fname,
1779                                         $options,
1780                                         $join_conds
1781                                 )
1782                         ],
1783                         [ 'rowcount' => 'COUNT(*)' ],
1784                         [],
1785                         $fname
1786                 );
1787                 $row = $res ? $this->fetchRow( $res ) : [];
1788
1789                 return isset( $row['rowcount'] ) ? (int)$row['rowcount'] : 0;
1790         }
1791
1792         /**
1793          * @param array|string $conds
1794          * @param string $fname
1795          * @return array
1796          */
1797         final protected function normalizeConditions( $conds, $fname ) {
1798                 if ( $conds === null || $conds === false ) {
1799                         $this->queryLogger->warning(
1800                                 __METHOD__
1801                                 . ' called from '
1802                                 . $fname
1803                                 . ' with incorrect parameters: $conds must be a string or an array'
1804                         );
1805                         $conds = '';
1806                 }
1807
1808                 if ( !is_array( $conds ) ) {
1809                         $conds = ( $conds === '' ) ? [] : [ $conds ];
1810                 }
1811
1812                 return $conds;
1813         }
1814
1815         /**
1816          * @param array|string $var Field parameter in the style of select()
1817          * @return string|null Column name or null; ignores aliases
1818          * @throws DBUnexpectedError Errors out if multiple columns are given
1819          */
1820         final protected function extractSingleFieldFromList( $var ) {
1821                 if ( is_array( $var ) ) {
1822                         if ( !$var ) {
1823                                 $column = null;
1824                         } elseif ( count( $var ) == 1 ) {
1825                                 $column = isset( $var[0] ) ? $var[0] : reset( $var );
1826                         } else {
1827                                 throw new DBUnexpectedError( $this, __METHOD__ . ': got multiple columns.' );
1828                         }
1829                 } else {
1830                         $column = $var;
1831                 }
1832
1833                 return $column;
1834         }
1835
1836         /**
1837          * Removes most variables from an SQL query and replaces them with X or N for numbers.
1838          * It's only slightly flawed. Don't use for anything important.
1839          *
1840          * @param string $sql A SQL Query
1841          *
1842          * @return string
1843          */
1844         protected static function generalizeSQL( $sql ) {
1845                 # This does the same as the regexp below would do, but in such a way
1846                 # as to avoid crashing php on some large strings.
1847                 # $sql = preg_replace( "/'([^\\\\']|\\\\.)*'|\"([^\\\\\"]|\\\\.)*\"/", "'X'", $sql );
1848
1849                 $sql = str_replace( "\\\\", '', $sql );
1850                 $sql = str_replace( "\\'", '', $sql );
1851                 $sql = str_replace( "\\\"", '', $sql );
1852                 $sql = preg_replace( "/'.*'/s", "'X'", $sql );
1853                 $sql = preg_replace( '/".*"/s', "'X'", $sql );
1854
1855                 # All newlines, tabs, etc replaced by single space
1856                 $sql = preg_replace( '/\s+/', ' ', $sql );
1857
1858                 # All numbers => N,
1859                 # except the ones surrounded by characters, e.g. l10n
1860                 $sql = preg_replace( '/-?\d+(,-?\d+)+/s', 'N,...,N', $sql );
1861                 $sql = preg_replace( '/(?<![a-zA-Z])-?\d+(?![a-zA-Z])/s', 'N', $sql );
1862
1863                 return $sql;
1864         }
1865
1866         public function fieldExists( $table, $field, $fname = __METHOD__ ) {
1867                 $info = $this->fieldInfo( $table, $field );
1868
1869                 return (bool)$info;
1870         }
1871
1872         public function indexExists( $table, $index, $fname = __METHOD__ ) {
1873                 if ( !$this->tableExists( $table ) ) {
1874                         return null;
1875                 }
1876
1877                 $info = $this->indexInfo( $table, $index, $fname );
1878                 if ( is_null( $info ) ) {
1879                         return null;
1880                 } else {
1881                         return $info !== false;
1882                 }
1883         }
1884
1885         public function tableExists( $table, $fname = __METHOD__ ) {
1886                 $tableRaw = $this->tableName( $table, 'raw' );
1887                 if ( isset( $this->sessionTempTables[$tableRaw] ) ) {
1888                         return true; // already known to exist
1889                 }
1890
1891                 $table = $this->tableName( $table );
1892                 $ignoreErrors = true;
1893                 $res = $this->query( "SELECT 1 FROM $table LIMIT 1", $fname, $ignoreErrors );
1894
1895                 return (bool)$res;
1896         }
1897
1898         public function indexUnique( $table, $index ) {
1899                 $indexInfo = $this->indexInfo( $table, $index );
1900
1901                 if ( !$indexInfo ) {
1902                         return null;
1903                 }
1904
1905                 return !$indexInfo[0]->Non_unique;
1906         }
1907
1908         /**
1909          * Helper for Database::insert().
1910          *
1911          * @param array $options
1912          * @return string
1913          */
1914         protected function makeInsertOptions( $options ) {
1915                 return implode( ' ', $options );
1916         }
1917
1918         public function insert( $table, $a, $fname = __METHOD__, $options = [] ) {
1919                 # No rows to insert, easy just return now
1920                 if ( !count( $a ) ) {
1921                         return true;
1922                 }
1923
1924                 $table = $this->tableName( $table );
1925
1926                 if ( !is_array( $options ) ) {
1927                         $options = [ $options ];
1928                 }
1929
1930                 $fh = null;
1931                 if ( isset( $options['fileHandle'] ) ) {
1932                         $fh = $options['fileHandle'];
1933                 }
1934                 $options = $this->makeInsertOptions( $options );
1935
1936                 if ( isset( $a[0] ) && is_array( $a[0] ) ) {
1937                         $multi = true;
1938                         $keys = array_keys( $a[0] );
1939                 } else {
1940                         $multi = false;
1941                         $keys = array_keys( $a );
1942                 }
1943
1944                 $sql = 'INSERT ' . $options .
1945                         " INTO $table (" . implode( ',', $keys ) . ') VALUES ';
1946
1947                 if ( $multi ) {
1948                         $first = true;
1949                         foreach ( $a as $row ) {
1950                                 if ( $first ) {
1951                                         $first = false;
1952                                 } else {
1953                                         $sql .= ',';
1954                                 }
1955                                 $sql .= '(' . $this->makeList( $row ) . ')';
1956                         }
1957                 } else {
1958                         $sql .= '(' . $this->makeList( $a ) . ')';
1959                 }
1960
1961                 if ( $fh !== null && false === fwrite( $fh, $sql ) ) {
1962                         return false;
1963                 } elseif ( $fh !== null ) {
1964                         return true;
1965                 }
1966
1967                 return (bool)$this->query( $sql, $fname );
1968         }
1969
1970         /**
1971          * Make UPDATE options array for Database::makeUpdateOptions
1972          *
1973          * @param array $options
1974          * @return array
1975          */
1976         protected function makeUpdateOptionsArray( $options ) {
1977                 if ( !is_array( $options ) ) {
1978                         $options = [ $options ];
1979                 }
1980
1981                 $opts = [];
1982
1983                 if ( in_array( 'IGNORE', $options ) ) {
1984                         $opts[] = 'IGNORE';
1985                 }
1986
1987                 return $opts;
1988         }
1989
1990         /**
1991          * Make UPDATE options for the Database::update function
1992          *
1993          * @param array $options The options passed to Database::update
1994          * @return string
1995          */
1996         protected function makeUpdateOptions( $options ) {
1997                 $opts = $this->makeUpdateOptionsArray( $options );
1998
1999                 return implode( ' ', $opts );
2000         }
2001
2002         public function update( $table, $values, $conds, $fname = __METHOD__, $options = [] ) {
2003                 $table = $this->tableName( $table );
2004                 $opts = $this->makeUpdateOptions( $options );
2005                 $sql = "UPDATE $opts $table SET " . $this->makeList( $values, self::LIST_SET );
2006
2007                 if ( $conds !== [] && $conds !== '*' ) {
2008                         $sql .= " WHERE " . $this->makeList( $conds, self::LIST_AND );
2009                 }
2010
2011                 return (bool)$this->query( $sql, $fname );
2012         }
2013
2014         public function makeList( $a, $mode = self::LIST_COMMA ) {
2015                 if ( !is_array( $a ) ) {
2016                         throw new DBUnexpectedError( $this, __METHOD__ . ' called with incorrect parameters' );
2017                 }
2018
2019                 $first = true;
2020                 $list = '';
2021
2022                 foreach ( $a as $field => $value ) {
2023                         if ( !$first ) {
2024                                 if ( $mode == self::LIST_AND ) {
2025                                         $list .= ' AND ';
2026                                 } elseif ( $mode == self::LIST_OR ) {
2027                                         $list .= ' OR ';
2028                                 } else {
2029                                         $list .= ',';
2030                                 }
2031                         } else {
2032                                 $first = false;
2033                         }
2034
2035                         if ( ( $mode == self::LIST_AND || $mode == self::LIST_OR ) && is_numeric( $field ) ) {
2036                                 $list .= "($value)";
2037                         } elseif ( $mode == self::LIST_SET && is_numeric( $field ) ) {
2038                                 $list .= "$value";
2039                         } elseif (
2040                                 ( $mode == self::LIST_AND || $mode == self::LIST_OR ) && is_array( $value )
2041                         ) {
2042                                 // Remove null from array to be handled separately if found
2043                                 $includeNull = false;
2044                                 foreach ( array_keys( $value, null, true ) as $nullKey ) {
2045                                         $includeNull = true;
2046                                         unset( $value[$nullKey] );
2047                                 }
2048                                 if ( count( $value ) == 0 && !$includeNull ) {
2049                                         throw new InvalidArgumentException(
2050                                                 __METHOD__ . ": empty input for field $field" );
2051                                 } elseif ( count( $value ) == 0 ) {
2052                                         // only check if $field is null
2053                                         $list .= "$field IS NULL";
2054                                 } else {
2055                                         // IN clause contains at least one valid element
2056                                         if ( $includeNull ) {
2057                                                 // Group subconditions to ensure correct precedence
2058                                                 $list .= '(';
2059                                         }
2060                                         if ( count( $value ) == 1 ) {
2061                                                 // Special-case single values, as IN isn't terribly efficient
2062                                                 // Don't necessarily assume the single key is 0; we don't
2063                                                 // enforce linear numeric ordering on other arrays here.
2064                                                 $value = array_values( $value )[0];
2065                                                 $list .= $field . " = " . $this->addQuotes( $value );
2066                                         } else {
2067                                                 $list .= $field . " IN (" . $this->makeList( $value ) . ") ";
2068                                         }
2069                                         // if null present in array, append IS NULL
2070                                         if ( $includeNull ) {
2071                                                 $list .= " OR $field IS NULL)";
2072                                         }
2073                                 }
2074                         } elseif ( $value === null ) {
2075                                 if ( $mode == self::LIST_AND || $mode == self::LIST_OR ) {
2076                                         $list .= "$field IS ";
2077                                 } elseif ( $mode == self::LIST_SET ) {
2078                                         $list .= "$field = ";
2079                                 }
2080                                 $list .= 'NULL';
2081                         } else {
2082                                 if (
2083                                         $mode == self::LIST_AND || $mode == self::LIST_OR || $mode == self::LIST_SET
2084                                 ) {
2085                                         $list .= "$field = ";
2086                                 }
2087                                 $list .= $mode == self::LIST_NAMES ? $value : $this->addQuotes( $value );
2088                         }
2089                 }
2090
2091                 return $list;
2092         }
2093
2094         public function makeWhereFrom2d( $data, $baseKey, $subKey ) {
2095                 $conds = [];
2096
2097                 foreach ( $data as $base => $sub ) {
2098                         if ( count( $sub ) ) {
2099                                 $conds[] = $this->makeList(
2100                                         [ $baseKey => $base, $subKey => array_keys( $sub ) ],
2101                                         self::LIST_AND );
2102                         }
2103                 }
2104
2105                 if ( $conds ) {
2106                         return $this->makeList( $conds, self::LIST_OR );
2107                 } else {
2108                         // Nothing to search for...
2109                         return false;
2110                 }
2111         }
2112
2113         public function aggregateValue( $valuedata, $valuename = 'value' ) {
2114                 return $valuename;
2115         }
2116
2117         public function bitNot( $field ) {
2118                 return "(~$field)";
2119         }
2120
2121         public function bitAnd( $fieldLeft, $fieldRight ) {
2122                 return "($fieldLeft & $fieldRight)";
2123         }
2124
2125         public function bitOr( $fieldLeft, $fieldRight ) {
2126                 return "($fieldLeft | $fieldRight)";
2127         }
2128
2129         public function buildConcat( $stringList ) {
2130                 return 'CONCAT(' . implode( ',', $stringList ) . ')';
2131         }
2132
2133         public function buildGroupConcatField(
2134                 $delim, $table, $field, $conds = '', $join_conds = []
2135         ) {
2136                 $fld = "GROUP_CONCAT($field SEPARATOR " . $this->addQuotes( $delim ) . ')';
2137
2138                 return '(' . $this->selectSQLText( $table, $fld, $conds, null, [], $join_conds ) . ')';
2139         }
2140
2141         public function buildSubstring( $input, $startPosition, $length = null ) {
2142                 $this->assertBuildSubstringParams( $startPosition, $length );
2143                 $functionBody = "$input FROM $startPosition";
2144                 if ( $length !== null ) {
2145                         $functionBody .= " FOR $length";
2146                 }
2147                 return 'SUBSTRING(' . $functionBody . ')';
2148         }
2149
2150         /**
2151          * Check type and bounds for parameters to self::buildSubstring()
2152          *
2153          * All supported databases have substring functions that behave the same for
2154          * positive $startPosition and non-negative $length, but behaviors differ when
2155          * given 0 or negative $startPosition or negative $length. The simplest
2156          * solution to that is to just forbid those values.
2157          *
2158          * @param int $startPosition
2159          * @param int|null $length
2160          * @since 1.31
2161          */
2162         protected function assertBuildSubstringParams( $startPosition, $length ) {
2163                 if ( !is_int( $startPosition ) || $startPosition <= 0 ) {
2164                         throw new InvalidArgumentException(
2165                                 '$startPosition must be a positive integer'
2166                         );
2167                 }
2168                 if ( !( is_int( $length ) && $length >= 0 || $length === null ) ) {
2169                         throw new InvalidArgumentException(
2170                                 '$length must be null or an integer greater than or equal to 0'
2171                         );
2172                 }
2173         }
2174
2175         public function buildStringCast( $field ) {
2176                 return $field;
2177         }
2178
2179         public function buildIntegerCast( $field ) {
2180                 return 'CAST( ' . $field . ' AS INTEGER )';
2181         }
2182
2183         public function buildSelectSubquery(
2184                 $table, $vars, $conds = '', $fname = __METHOD__,
2185                 $options = [], $join_conds = []
2186         ) {
2187                 return new Subquery(
2188                         $this->selectSQLText( $table, $vars, $conds, $fname, $options, $join_conds )
2189                 );
2190         }
2191
2192         public function databasesAreIndependent() {
2193                 return false;
2194         }
2195
2196         public function selectDB( $db ) {
2197                 # Stub. Shouldn't cause serious problems if it's not overridden, but
2198                 # if your database engine supports a concept similar to MySQL's
2199                 # databases you may as well.
2200                 $this->dbName = $db;
2201
2202                 return true;
2203         }
2204
2205         public function getDBname() {
2206                 return $this->dbName;
2207         }
2208
2209         public function getServer() {
2210                 return $this->server;
2211         }
2212
2213         public function tableName( $name, $format = 'quoted' ) {
2214                 if ( $name instanceof Subquery ) {
2215                         throw new DBUnexpectedError(
2216                                 $this,
2217                                 __METHOD__ . ': got Subquery instance when expecting a string.'
2218                         );
2219                 }
2220
2221                 # Skip the entire process when we have a string quoted on both ends.
2222                 # Note that we check the end so that we will still quote any use of
2223                 # use of `database`.table. But won't break things if someone wants
2224                 # to query a database table with a dot in the name.
2225                 if ( $this->isQuotedIdentifier( $name ) ) {
2226                         return $name;
2227                 }
2228
2229                 # Lets test for any bits of text that should never show up in a table
2230                 # name. Basically anything like JOIN or ON which are actually part of
2231                 # SQL queries, but may end up inside of the table value to combine
2232                 # sql. Such as how the API is doing.
2233                 # Note that we use a whitespace test rather than a \b test to avoid
2234                 # any remote case where a word like on may be inside of a table name
2235                 # surrounded by symbols which may be considered word breaks.
2236                 if ( preg_match( '/(^|\s)(DISTINCT|JOIN|ON|AS)(\s|$)/i', $name ) !== 0 ) {
2237                         $this->queryLogger->warning(
2238                                 __METHOD__ . ": use of subqueries is not supported this way.",
2239                                 [ 'trace' => ( new RuntimeException() )->getTraceAsString() ]
2240                         );
2241
2242                         return $name;
2243                 }
2244
2245                 # Split database and table into proper variables.
2246                 list( $database, $schema, $prefix, $table ) = $this->qualifiedTableComponents( $name );
2247
2248                 # Quote $table and apply the prefix if not quoted.
2249                 # $tableName might be empty if this is called from Database::replaceVars()
2250                 $tableName = "{$prefix}{$table}";
2251                 if ( $format === 'quoted'
2252                         && !$this->isQuotedIdentifier( $tableName )
2253                         && $tableName !== ''
2254                 ) {
2255                         $tableName = $this->addIdentifierQuotes( $tableName );
2256                 }
2257
2258                 # Quote $schema and $database and merge them with the table name if needed
2259                 $tableName = $this->prependDatabaseOrSchema( $schema, $tableName, $format );
2260                 $tableName = $this->prependDatabaseOrSchema( $database, $tableName, $format );
2261
2262                 return $tableName;
2263         }
2264
2265         /**
2266          * Get the table components needed for a query given the currently selected database
2267          *
2268          * @param string $name Table name in the form of db.schema.table, db.table, or table
2269          * @return array (DB name or "" for default, schema name, table prefix, table name)
2270          */
2271         protected function qualifiedTableComponents( $name ) {
2272                 # We reverse the explode so that database.table and table both output the correct table.
2273                 $dbDetails = explode( '.', $name, 3 );
2274                 if ( count( $dbDetails ) == 3 ) {
2275                         list( $database, $schema, $table ) = $dbDetails;
2276                         # We don't want any prefix added in this case
2277                         $prefix = '';
2278                 } elseif ( count( $dbDetails ) == 2 ) {
2279                         list( $database, $table ) = $dbDetails;
2280                         # We don't want any prefix added in this case
2281                         $prefix = '';
2282                         # In dbs that support it, $database may actually be the schema
2283                         # but that doesn't affect any of the functionality here
2284                         $schema = '';
2285                 } else {
2286                         list( $table ) = $dbDetails;
2287                         if ( isset( $this->tableAliases[$table] ) ) {
2288                                 $database = $this->tableAliases[$table]['dbname'];
2289                                 $schema = is_string( $this->tableAliases[$table]['schema'] )
2290                                         ? $this->tableAliases[$table]['schema']
2291                                         : $this->schema;
2292                                 $prefix = is_string( $this->tableAliases[$table]['prefix'] )
2293                                         ? $this->tableAliases[$table]['prefix']
2294                                         : $this->tablePrefix;
2295                         } else {
2296                                 $database = '';
2297                                 $schema = $this->schema; # Default schema
2298                                 $prefix = $this->tablePrefix; # Default prefix
2299                         }
2300                 }
2301
2302                 return [ $database, $schema, $prefix, $table ];
2303         }
2304
2305         /**
2306          * @param string|null $namespace Database or schema
2307          * @param string $relation Name of table, view, sequence, etc...
2308          * @param string $format One of (raw, quoted)
2309          * @return string Relation name with quoted and merged $namespace as needed
2310          */
2311         private function prependDatabaseOrSchema( $namespace, $relation, $format ) {
2312                 if ( strlen( $namespace ) ) {
2313                         if ( $format === 'quoted' && !$this->isQuotedIdentifier( $namespace ) ) {
2314                                 $namespace = $this->addIdentifierQuotes( $namespace );
2315                         }
2316                         $relation = $namespace . '.' . $relation;
2317                 }
2318
2319                 return $relation;
2320         }
2321
2322         public function tableNames() {
2323                 $inArray = func_get_args();
2324                 $retVal = [];
2325
2326                 foreach ( $inArray as $name ) {
2327                         $retVal[$name] = $this->tableName( $name );
2328                 }
2329
2330                 return $retVal;
2331         }
2332
2333         public function tableNamesN() {
2334                 $inArray = func_get_args();
2335                 $retVal = [];
2336
2337                 foreach ( $inArray as $name ) {
2338                         $retVal[] = $this->tableName( $name );
2339                 }
2340
2341                 return $retVal;
2342         }
2343
2344         /**
2345          * Get an aliased table name
2346          *
2347          * This returns strings like "tableName AS newTableName" for aliased tables
2348          * and "(SELECT * from tableA) newTablename" for subqueries (e.g. derived tables)
2349          *
2350          * @see Database::tableName()
2351          * @param string|Subquery $table Table name or object with a 'sql' field
2352          * @param string|bool $alias Table alias (optional)
2353          * @return string SQL name for aliased table. Will not alias a table to its own name
2354          */
2355         protected function tableNameWithAlias( $table, $alias = false ) {
2356                 if ( is_string( $table ) ) {
2357                         $quotedTable = $this->tableName( $table );
2358                 } elseif ( $table instanceof Subquery ) {
2359                         $quotedTable = (string)$table;
2360                 } else {
2361                         throw new InvalidArgumentException( "Table must be a string or Subquery." );
2362                 }
2363
2364                 if ( !strlen( $alias ) || $alias === $table ) {
2365                         if ( $table instanceof Subquery ) {
2366                                 throw new InvalidArgumentException( "Subquery table missing alias." );
2367                         }
2368
2369                         return $quotedTable;
2370                 } else {
2371                         return $quotedTable . ' ' . $this->addIdentifierQuotes( $alias );
2372                 }
2373         }
2374
2375         /**
2376          * Gets an array of aliased table names
2377          *
2378          * @param array $tables [ [alias] => table ]
2379          * @return string[] See tableNameWithAlias()
2380          */
2381         protected function tableNamesWithAlias( $tables ) {
2382                 $retval = [];
2383                 foreach ( $tables as $alias => $table ) {
2384                         if ( is_numeric( $alias ) ) {
2385                                 $alias = $table;
2386                         }
2387                         $retval[] = $this->tableNameWithAlias( $table, $alias );
2388                 }
2389
2390                 return $retval;
2391         }
2392
2393         /**
2394          * Get an aliased field name
2395          * e.g. fieldName AS newFieldName
2396          *
2397          * @param string $name Field name
2398          * @param string|bool $alias Alias (optional)
2399          * @return string SQL name for aliased field. Will not alias a field to its own name
2400          */
2401         protected function fieldNameWithAlias( $name, $alias = false ) {
2402                 if ( !$alias || (string)$alias === (string)$name ) {
2403                         return $name;
2404                 } else {
2405                         return $name . ' AS ' . $this->addIdentifierQuotes( $alias ); // PostgreSQL needs AS
2406                 }
2407         }
2408
2409         /**
2410          * Gets an array of aliased field names
2411          *
2412          * @param array $fields [ [alias] => field ]
2413          * @return string[] See fieldNameWithAlias()
2414          */
2415         protected function fieldNamesWithAlias( $fields ) {
2416                 $retval = [];
2417                 foreach ( $fields as $alias => $field ) {
2418                         if ( is_numeric( $alias ) ) {
2419                                 $alias = $field;
2420                         }
2421                         $retval[] = $this->fieldNameWithAlias( $field, $alias );
2422                 }
2423
2424                 return $retval;
2425         }
2426
2427         /**
2428          * Get the aliased table name clause for a FROM clause
2429          * which might have a JOIN and/or USE INDEX or IGNORE INDEX clause
2430          *
2431          * @param array $tables ( [alias] => table )
2432          * @param array $use_index Same as for select()
2433          * @param array $ignore_index Same as for select()
2434          * @param array $join_conds Same as for select()
2435          * @return string
2436          */
2437         protected function tableNamesWithIndexClauseOrJOIN(
2438                 $tables, $use_index = [], $ignore_index = [], $join_conds = []
2439         ) {
2440                 $ret = [];
2441                 $retJOIN = [];
2442                 $use_index = (array)$use_index;
2443                 $ignore_index = (array)$ignore_index;
2444                 $join_conds = (array)$join_conds;
2445
2446                 foreach ( $tables as $alias => $table ) {
2447                         if ( !is_string( $alias ) ) {
2448                                 // No alias? Set it equal to the table name
2449                                 $alias = $table;
2450                         }
2451
2452                         if ( is_array( $table ) ) {
2453                                 // A parenthesized group
2454                                 if ( count( $table ) > 1 ) {
2455                                         $joinedTable = '(' .
2456                                                 $this->tableNamesWithIndexClauseOrJOIN(
2457                                                         $table, $use_index, $ignore_index, $join_conds ) . ')';
2458                                 } else {
2459                                         // Degenerate case
2460                                         $innerTable = reset( $table );
2461                                         $innerAlias = key( $table );
2462                                         $joinedTable = $this->tableNameWithAlias(
2463                                                 $innerTable,
2464                                                 is_string( $innerAlias ) ? $innerAlias : $innerTable
2465                                         );
2466                                 }
2467                         } else {
2468                                 $joinedTable = $this->tableNameWithAlias( $table, $alias );
2469                         }
2470
2471                         // Is there a JOIN clause for this table?
2472                         if ( isset( $join_conds[$alias] ) ) {
2473                                 list( $joinType, $conds ) = $join_conds[$alias];
2474                                 $tableClause = $joinType;
2475                                 $tableClause .= ' ' . $joinedTable;
2476                                 if ( isset( $use_index[$alias] ) ) { // has USE INDEX?
2477                                         $use = $this->useIndexClause( implode( ',', (array)$use_index[$alias] ) );
2478                                         if ( $use != '' ) {
2479                                                 $tableClause .= ' ' . $use;
2480                                         }
2481                                 }
2482                                 if ( isset( $ignore_index[$alias] ) ) { // has IGNORE INDEX?
2483                                         $ignore = $this->ignoreIndexClause(
2484                                                 implode( ',', (array)$ignore_index[$alias] ) );
2485                                         if ( $ignore != '' ) {
2486                                                 $tableClause .= ' ' . $ignore;
2487                                         }
2488                                 }
2489                                 $on = $this->makeList( (array)$conds, self::LIST_AND );
2490                                 if ( $on != '' ) {
2491                                         $tableClause .= ' ON (' . $on . ')';
2492                                 }
2493
2494                                 $retJOIN[] = $tableClause;
2495                         } elseif ( isset( $use_index[$alias] ) ) {
2496                                 // Is there an INDEX clause for this table?
2497                                 $tableClause = $joinedTable;
2498                                 $tableClause .= ' ' . $this->useIndexClause(
2499                                                 implode( ',', (array)$use_index[$alias] )
2500                                         );
2501
2502                                 $ret[] = $tableClause;
2503                         } elseif ( isset( $ignore_index[$alias] ) ) {
2504                                 // Is there an INDEX clause for this table?
2505                                 $tableClause = $joinedTable;
2506                                 $tableClause .= ' ' . $this->ignoreIndexClause(
2507                                                 implode( ',', (array)$ignore_index[$alias] )
2508                                         );
2509
2510                                 $ret[] = $tableClause;
2511                         } else {
2512                                 $tableClause = $joinedTable;
2513
2514                                 $ret[] = $tableClause;
2515                         }
2516                 }
2517
2518                 // We can't separate explicit JOIN clauses with ',', use ' ' for those
2519                 $implicitJoins = $ret ? implode( ',', $ret ) : "";
2520                 $explicitJoins = $retJOIN ? implode( ' ', $retJOIN ) : "";
2521
2522                 // Compile our final table clause
2523                 return implode( ' ', [ $implicitJoins, $explicitJoins ] );
2524         }
2525
2526         /**
2527          * Allows for index remapping in queries where this is not consistent across DBMS
2528          *
2529          * @param string $index
2530          * @return string
2531          */
2532         protected function indexName( $index ) {
2533                 return isset( $this->indexAliases[$index] )
2534                         ? $this->indexAliases[$index]
2535                         : $index;
2536         }
2537
2538         public function addQuotes( $s ) {
2539                 if ( $s instanceof Blob ) {
2540                         $s = $s->fetch();
2541                 }
2542                 if ( $s === null ) {
2543                         return 'NULL';
2544                 } elseif ( is_bool( $s ) ) {
2545                         return (int)$s;
2546                 } else {
2547                         # This will also quote numeric values. This should be harmless,
2548                         # and protects against weird problems that occur when they really
2549                         # _are_ strings such as article titles and string->number->string
2550                         # conversion is not 1:1.
2551                         return "'" . $this->strencode( $s ) . "'";
2552                 }
2553         }
2554
2555         /**
2556          * Quotes an identifier using `backticks` or "double quotes" depending on the database type.
2557          * MySQL uses `backticks` while basically everything else uses double quotes.
2558          * Since MySQL is the odd one out here the double quotes are our generic
2559          * and we implement backticks in DatabaseMysqlBase.
2560          *
2561          * @param string $s
2562          * @return string
2563          */
2564         public function addIdentifierQuotes( $s ) {
2565                 return '"' . str_replace( '"', '""', $s ) . '"';
2566         }
2567
2568         /**
2569          * Returns if the given identifier looks quoted or not according to
2570          * the database convention for quoting identifiers .
2571          *
2572          * @note Do not use this to determine if untrusted input is safe.
2573          *   A malicious user can trick this function.
2574          * @param string $name
2575          * @return bool
2576          */
2577         public function isQuotedIdentifier( $name ) {
2578                 return $name[0] == '"' && substr( $name, -1, 1 ) == '"';
2579         }
2580
2581         /**
2582          * @param string $s
2583          * @param string $escapeChar
2584          * @return string
2585          */
2586         protected function escapeLikeInternal( $s, $escapeChar = '`' ) {
2587                 return str_replace( [ $escapeChar, '%', '_' ],
2588                         [ "{$escapeChar}{$escapeChar}", "{$escapeChar}%", "{$escapeChar}_" ],
2589                         $s );
2590         }
2591
2592         public function buildLike() {
2593                 $params = func_get_args();
2594
2595                 if ( count( $params ) > 0 && is_array( $params[0] ) ) {
2596                         $params = $params[0];
2597                 }
2598
2599                 $s = '';
2600
2601                 // We use ` instead of \ as the default LIKE escape character, since addQuotes()
2602                 // may escape backslashes, creating problems of double escaping. The `
2603                 // character has good cross-DBMS compatibility, avoiding special operators
2604                 // in MS SQL like ^ and %
2605                 $escapeChar = '`';
2606
2607                 foreach ( $params as $value ) {
2608                         if ( $value instanceof LikeMatch ) {
2609                                 $s .= $value->toString();
2610                         } else {
2611                                 $s .= $this->escapeLikeInternal( $value, $escapeChar );
2612                         }
2613                 }
2614
2615                 return ' LIKE ' .
2616                         $this->addQuotes( $s ) . ' ESCAPE ' . $this->addQuotes( $escapeChar ) . ' ';
2617         }
2618
2619         public function anyChar() {
2620                 return new LikeMatch( '_' );
2621         }
2622
2623         public function anyString() {
2624                 return new LikeMatch( '%' );
2625         }
2626
2627         public function nextSequenceValue( $seqName ) {
2628                 return null;
2629         }
2630
2631         /**
2632          * USE INDEX clause. Unlikely to be useful for anything but MySQL. This
2633          * is only needed because a) MySQL must be as efficient as possible due to
2634          * its use on Wikipedia, and b) MySQL 4.0 is kind of dumb sometimes about
2635          * which index to pick. Anyway, other databases might have different
2636          * indexes on a given table. So don't bother overriding this unless you're
2637          * MySQL.
2638          * @param string $index
2639          * @return string
2640          */
2641         public function useIndexClause( $index ) {
2642                 return '';
2643         }
2644
2645         /**
2646          * IGNORE INDEX clause. Unlikely to be useful for anything but MySQL. This
2647          * is only needed because a) MySQL must be as efficient as possible due to
2648          * its use on Wikipedia, and b) MySQL 4.0 is kind of dumb sometimes about
2649          * which index to pick. Anyway, other databases might have different
2650          * indexes on a given table. So don't bother overriding this unless you're
2651          * MySQL.
2652          * @param string $index
2653          * @return string
2654          */
2655         public function ignoreIndexClause( $index ) {
2656                 return '';
2657         }
2658
2659         public function replace( $table, $uniqueIndexes, $rows, $fname = __METHOD__ ) {
2660                 if ( count( $rows ) == 0 ) {
2661                         return;
2662                 }
2663
2664                 // Single row case
2665                 if ( !is_array( reset( $rows ) ) ) {
2666                         $rows = [ $rows ];
2667                 }
2668
2669                 try {
2670                         $this->startAtomic( $fname, self::ATOMIC_CANCELABLE );
2671                         $affectedRowCount = 0;
2672                         foreach ( $rows as $row ) {
2673                                 // Delete rows which collide with this one
2674                                 $indexWhereClauses = [];
2675                                 foreach ( $uniqueIndexes as $index ) {
2676                                         $indexColumns = (array)$index;
2677                                         $indexRowValues = array_intersect_key( $row, array_flip( $indexColumns ) );
2678                                         if ( count( $indexRowValues ) != count( $indexColumns ) ) {
2679                                                 throw new DBUnexpectedError(
2680                                                         $this,
2681                                                         'New record does not provide all values for unique key (' .
2682                                                         implode( ', ', $indexColumns ) . ')'
2683                                                 );
2684                                         } elseif ( in_array( null, $indexRowValues, true ) ) {
2685                                                 throw new DBUnexpectedError(
2686                                                         $this,
2687                                                         'New record has a null value for unique key (' .
2688                                                         implode( ', ', $indexColumns ) . ')'
2689                                                 );
2690                                         }
2691                                         $indexWhereClauses[] = $this->makeList( $indexRowValues, LIST_AND );
2692                                 }
2693
2694                                 if ( $indexWhereClauses ) {
2695                                         $this->delete( $table, $this->makeList( $indexWhereClauses, LIST_OR ), $fname );
2696                                         $affectedRowCount += $this->affectedRows();
2697                                 }
2698
2699                                 // Now insert the row
2700                                 $this->insert( $table, $row, $fname );
2701                                 $affectedRowCount += $this->affectedRows();
2702                         }
2703                         $this->endAtomic( $fname );
2704                         $this->affectedRowCount = $affectedRowCount;
2705                 } catch ( Exception $e ) {
2706                         $this->cancelAtomic( $fname );
2707                         throw $e;
2708                 }
2709         }
2710
2711         /**
2712          * REPLACE query wrapper for MySQL and SQLite, which have a native REPLACE
2713          * statement.
2714          *
2715          * @param string $table Table name
2716          * @param array|string $rows Row(s) to insert
2717          * @param string $fname Caller function name
2718          *
2719          * @return ResultWrapper
2720          */
2721         protected function nativeReplace( $table, $rows, $fname ) {
2722                 $table = $this->tableName( $table );
2723
2724                 # Single row case
2725                 if ( !is_array( reset( $rows ) ) ) {
2726                         $rows = [ $rows ];
2727                 }
2728
2729                 $sql = "REPLACE INTO $table (" . implode( ',', array_keys( $rows[0] ) ) . ') VALUES ';
2730                 $first = true;
2731
2732                 foreach ( $rows as $row ) {
2733                         if ( $first ) {
2734                                 $first = false;
2735                         } else {
2736                                 $sql .= ',';
2737                         }
2738
2739                         $sql .= '(' . $this->makeList( $row ) . ')';
2740                 }
2741
2742                 return $this->query( $sql, $fname );
2743         }
2744
2745         public function upsert( $table, array $rows, array $uniqueIndexes, array $set,
2746                 $fname = __METHOD__
2747         ) {
2748                 if ( !count( $rows ) ) {
2749                         return true; // nothing to do
2750                 }
2751
2752                 if ( !is_array( reset( $rows ) ) ) {
2753                         $rows = [ $rows ];
2754                 }
2755
2756                 if ( count( $uniqueIndexes ) ) {
2757                         $clauses = []; // list WHERE clauses that each identify a single row
2758                         foreach ( $rows as $row ) {
2759                                 foreach ( $uniqueIndexes as $index ) {
2760                                         $index = is_array( $index ) ? $index : [ $index ]; // columns
2761                                         $rowKey = []; // unique key to this row
2762                                         foreach ( $index as $column ) {
2763                                                 $rowKey[$column] = $row[$column];
2764                                         }
2765                                         $clauses[] = $this->makeList( $rowKey, self::LIST_AND );
2766                                 }
2767                         }
2768                         $where = [ $this->makeList( $clauses, self::LIST_OR ) ];
2769                 } else {
2770                         $where = false;
2771                 }
2772
2773                 $affectedRowCount = 0;
2774                 try {
2775                         $this->startAtomic( $fname, self::ATOMIC_CANCELABLE );
2776                         # Update any existing conflicting row(s)
2777                         if ( $where !== false ) {
2778                                 $ok = $this->update( $table, $set, $where, $fname );
2779                                 $affectedRowCount += $this->affectedRows();
2780                         } else {
2781                                 $ok = true;
2782                         }
2783                         # Now insert any non-conflicting row(s)
2784                         $ok = $this->insert( $table, $rows, $fname, [ 'IGNORE' ] ) && $ok;
2785                         $affectedRowCount += $this->affectedRows();
2786                         $this->endAtomic( $fname );
2787                         $this->affectedRowCount = $affectedRowCount;
2788                 } catch ( Exception $e ) {
2789                         $this->cancelAtomic( $fname );
2790                         throw $e;
2791                 }
2792
2793                 return $ok;
2794         }
2795
2796         public function deleteJoin( $delTable, $joinTable, $delVar, $joinVar, $conds,
2797                 $fname = __METHOD__
2798         ) {
2799                 if ( !$conds ) {
2800                         throw new DBUnexpectedError( $this, __METHOD__ . ' called with empty $conds' );
2801                 }
2802
2803                 $delTable = $this->tableName( $delTable );
2804                 $joinTable = $this->tableName( $joinTable );
2805                 $sql = "DELETE FROM $delTable WHERE $delVar IN (SELECT $joinVar FROM $joinTable ";
2806                 if ( $conds != '*' ) {
2807                         $sql .= 'WHERE ' . $this->makeList( $conds, self::LIST_AND );
2808                 }
2809                 $sql .= ')';
2810
2811                 $this->query( $sql, $fname );
2812         }
2813
2814         public function textFieldSize( $table, $field ) {
2815                 $table = $this->tableName( $table );
2816                 $sql = "SHOW COLUMNS FROM $table LIKE \"$field\";";
2817                 $res = $this->query( $sql, __METHOD__ );
2818                 $row = $this->fetchObject( $res );
2819
2820                 $m = [];
2821
2822                 if ( preg_match( '/\((.*)\)/', $row->Type, $m ) ) {
2823                         $size = $m[1];
2824                 } else {
2825                         $size = -1;
2826                 }
2827
2828                 return $size;
2829         }
2830
2831         public function delete( $table, $conds, $fname = __METHOD__ ) {
2832                 if ( !$conds ) {
2833                         throw new DBUnexpectedError( $this, __METHOD__ . ' called with no conditions' );
2834                 }
2835
2836                 $table = $this->tableName( $table );
2837                 $sql = "DELETE FROM $table";
2838
2839                 if ( $conds != '*' ) {
2840                         if ( is_array( $conds ) ) {
2841                                 $conds = $this->makeList( $conds, self::LIST_AND );
2842                         }
2843                         $sql .= ' WHERE ' . $conds;
2844                 }
2845
2846                 return $this->query( $sql, $fname );
2847         }
2848
2849         final public function insertSelect(
2850                 $destTable, $srcTable, $varMap, $conds,
2851                 $fname = __METHOD__, $insertOptions = [], $selectOptions = [], $selectJoinConds = []
2852         ) {
2853                 static $hints = [ 'NO_AUTO_COLUMNS' ];
2854
2855                 $insertOptions = (array)$insertOptions;
2856                 $selectOptions = (array)$selectOptions;
2857
2858                 if ( $this->cliMode && $this->isInsertSelectSafe( $insertOptions, $selectOptions ) ) {
2859                         // For massive migrations with downtime, we don't want to select everything
2860                         // into memory and OOM, so do all this native on the server side if possible.
2861                         return $this->nativeInsertSelect(
2862                                 $destTable,
2863                                 $srcTable,
2864                                 $varMap,
2865                                 $conds,
2866                                 $fname,
2867                                 array_diff( $insertOptions, $hints ),
2868                                 $selectOptions,
2869                                 $selectJoinConds
2870                         );
2871                 }
2872
2873                 return $this->nonNativeInsertSelect(
2874                         $destTable,
2875                         $srcTable,
2876                         $varMap,
2877                         $conds,
2878                         $fname,
2879                         array_diff( $insertOptions, $hints ),
2880                         $selectOptions,
2881                         $selectJoinConds
2882                 );
2883         }
2884
2885         /**
2886          * @param array $insertOptions INSERT options
2887          * @param array $selectOptions SELECT options
2888          * @return bool Whether an INSERT SELECT with these options will be replication safe
2889          * @since 1.31
2890          */
2891         protected function isInsertSelectSafe( array $insertOptions, array $selectOptions ) {
2892                 return true;
2893         }
2894
2895         /**
2896          * Implementation of insertSelect() based on select() and insert()
2897          *
2898          * @see IDatabase::insertSelect()
2899          * @since 1.30
2900          * @param string $destTable
2901          * @param string|array $srcTable
2902          * @param array $varMap
2903          * @param array $conds
2904          * @param string $fname
2905          * @param array $insertOptions
2906          * @param array $selectOptions
2907          * @param array $selectJoinConds
2908          * @return bool
2909          */
2910         protected function nonNativeInsertSelect( $destTable, $srcTable, $varMap, $conds,
2911                 $fname = __METHOD__,
2912                 $insertOptions = [], $selectOptions = [], $selectJoinConds = []
2913         ) {
2914                 // For web requests, do a locking SELECT and then INSERT. This puts the SELECT burden
2915                 // on only the master (without needing row-based-replication). It also makes it easy to
2916                 // know how big the INSERT is going to be.
2917                 $fields = [];
2918                 foreach ( $varMap as $dstColumn => $sourceColumnOrSql ) {
2919                         $fields[] = $this->fieldNameWithAlias( $sourceColumnOrSql, $dstColumn );
2920                 }
2921                 $selectOptions[] = 'FOR UPDATE';
2922                 $res = $this->select(
2923                         $srcTable, implode( ',', $fields ), $conds, $fname, $selectOptions, $selectJoinConds
2924                 );
2925                 if ( !$res ) {
2926                         return false;
2927                 }
2928
2929                 try {
2930                         $affectedRowCount = 0;
2931                         $this->startAtomic( $fname, self::ATOMIC_CANCELABLE );
2932                         $rows = [];
2933                         $ok = true;
2934                         foreach ( $res as $row ) {
2935                                 $rows[] = (array)$row;
2936
2937                                 // Avoid inserts that are too huge
2938                                 if ( count( $rows ) >= $this->nonNativeInsertSelectBatchSize ) {
2939                                         $ok = $this->insert( $destTable, $rows, $fname, $insertOptions );
2940                                         if ( !$ok ) {
2941                                                 break;
2942                                         }
2943                                         $affectedRowCount += $this->affectedRows();
2944                                         $rows = [];
2945                                 }
2946                         }
2947                         if ( $rows && $ok ) {
2948                                 $ok = $this->insert( $destTable, $rows, $fname, $insertOptions );
2949                                 if ( $ok ) {
2950                                         $affectedRowCount += $this->affectedRows();
2951                                 }
2952                         }
2953                         if ( $ok ) {
2954                                 $this->endAtomic( $fname );
2955                                 $this->affectedRowCount = $affectedRowCount;
2956                         } else {
2957                                 $this->cancelAtomic( $fname );
2958                         }
2959                         return $ok;
2960                 } catch ( Exception $e ) {
2961                         $this->cancelAtomic( $fname );
2962                         throw $e;
2963                 }
2964         }
2965
2966         /**
2967          * Native server-side implementation of insertSelect() for situations where
2968          * we don't want to select everything into memory
2969          *
2970          * @see IDatabase::insertSelect()
2971          * @param string $destTable
2972          * @param string|array $srcTable
2973          * @param array $varMap
2974          * @param array $conds
2975          * @param string $fname
2976          * @param array $insertOptions
2977          * @param array $selectOptions
2978          * @param array $selectJoinConds
2979          * @return bool
2980          */
2981         protected function nativeInsertSelect( $destTable, $srcTable, $varMap, $conds,
2982                 $fname = __METHOD__,
2983                 $insertOptions = [], $selectOptions = [], $selectJoinConds = []
2984         ) {
2985                 $destTable = $this->tableName( $destTable );
2986
2987                 if ( !is_array( $insertOptions ) ) {
2988                         $insertOptions = [ $insertOptions ];
2989                 }
2990
2991                 $insertOptions = $this->makeInsertOptions( $insertOptions );
2992
2993                 $selectSql = $this->selectSQLText(
2994                         $srcTable,
2995                         array_values( $varMap ),
2996                         $conds,
2997                         $fname,
2998                         $selectOptions,
2999                         $selectJoinConds
3000                 );
3001
3002                 $sql = "INSERT $insertOptions" .
3003                         " INTO $destTable (" . implode( ',', array_keys( $varMap ) ) . ') ' .
3004                         $selectSql;
3005
3006                 return $this->query( $sql, $fname );
3007         }
3008
3009         /**
3010          * Construct a LIMIT query with optional offset. This is used for query
3011          * pages. The SQL should be adjusted so that only the first $limit rows
3012          * are returned. If $offset is provided as well, then the first $offset
3013          * rows should be discarded, and the next $limit rows should be returned.
3014          * If the result of the query is not ordered, then the rows to be returned
3015          * are theoretically arbitrary.
3016          *
3017          * $sql is expected to be a SELECT, if that makes a difference.
3018          *
3019          * The version provided by default works in MySQL and SQLite. It will very
3020          * likely need to be overridden for most other DBMSes.
3021          *
3022          * @param string $sql SQL query we will append the limit too
3023          * @param int $limit The SQL limit
3024          * @param int|bool $offset The SQL offset (default false)
3025          * @throws DBUnexpectedError
3026          * @return string
3027          */
3028         public function limitResult( $sql, $limit, $offset = false ) {
3029                 if ( !is_numeric( $limit ) ) {
3030                         throw new DBUnexpectedError( $this,
3031                                 "Invalid non-numeric limit passed to limitResult()\n" );
3032                 }
3033
3034                 return "$sql LIMIT "
3035                 . ( ( is_numeric( $offset ) && $offset != 0 ) ? "{$offset}," : "" )
3036                 . "{$limit} ";
3037         }
3038
3039         public function unionSupportsOrderAndLimit() {
3040                 return true; // True for almost every DB supported
3041         }
3042
3043         public function unionQueries( $sqls, $all ) {
3044                 $glue = $all ? ') UNION ALL (' : ') UNION (';
3045
3046                 return '(' . implode( $glue, $sqls ) . ')';
3047         }
3048
3049         public function unionConditionPermutations(
3050                 $table, $vars, array $permute_conds, $extra_conds = '', $fname = __METHOD__,
3051                 $options = [], $join_conds = []
3052         ) {
3053                 // First, build the Cartesian product of $permute_conds
3054                 $conds = [ [] ];
3055                 foreach ( $permute_conds as $field => $values ) {
3056                         if ( !$values ) {
3057                                 // Skip empty $values
3058                                 continue;
3059                         }
3060                         $values = array_unique( $values ); // For sanity
3061                         $newConds = [];
3062                         foreach ( $conds as $cond ) {
3063                                 foreach ( $values as $value ) {
3064                                         $cond[$field] = $value;
3065                                         $newConds[] = $cond; // Arrays are by-value, not by-reference, so this works
3066                                 }
3067                         }
3068                         $conds = $newConds;
3069                 }
3070
3071                 $extra_conds = $extra_conds === '' ? [] : (array)$extra_conds;
3072
3073                 // If there's just one condition and no subordering, hand off to
3074                 // selectSQLText directly.
3075                 if ( count( $conds ) === 1 &&
3076                         ( !isset( $options['INNER ORDER BY'] ) || !$this->unionSupportsOrderAndLimit() )
3077                 ) {
3078                         return $this->selectSQLText(
3079                                 $table, $vars, $conds[0] + $extra_conds, $fname, $options, $join_conds
3080                         );
3081                 }
3082
3083                 // Otherwise, we need to pull out the order and limit to apply after
3084                 // the union. Then build the SQL queries for each set of conditions in
3085                 // $conds. Then union them together (using UNION ALL, because the
3086                 // product *should* already be distinct).
3087                 $orderBy = $this->makeOrderBy( $options );
3088                 $limit = isset( $options['LIMIT'] ) ? $options['LIMIT'] : null;
3089                 $offset = isset( $options['OFFSET'] ) ? $options['OFFSET'] : false;
3090                 $all = empty( $options['NOTALL'] ) && !in_array( 'NOTALL', $options );
3091                 if ( !$this->unionSupportsOrderAndLimit() ) {
3092                         unset( $options['ORDER BY'], $options['LIMIT'], $options['OFFSET'] );
3093                 } else {
3094                         if ( array_key_exists( 'INNER ORDER BY', $options ) ) {
3095                                 $options['ORDER BY'] = $options['INNER ORDER BY'];
3096                         }
3097                         if ( $limit !== null && is_numeric( $offset ) && $offset != 0 ) {
3098                                 // We need to increase the limit by the offset rather than
3099                                 // using the offset directly, otherwise it'll skip incorrectly
3100                                 // in the subqueries.
3101                                 $options['LIMIT'] = $limit + $offset;
3102                                 unset( $options['OFFSET'] );
3103                         }
3104                 }
3105
3106                 $sqls = [];
3107                 foreach ( $conds as $cond ) {
3108                         $sqls[] = $this->selectSQLText(
3109                                 $table, $vars, $cond + $extra_conds, $fname, $options, $join_conds
3110                         );
3111                 }
3112                 $sql = $this->unionQueries( $sqls, $all ) . $orderBy;
3113                 if ( $limit !== null ) {
3114                         $sql = $this->limitResult( $sql, $limit, $offset );
3115                 }
3116
3117                 return $sql;
3118         }
3119
3120         public function conditional( $cond, $trueVal, $falseVal ) {
3121                 if ( is_array( $cond ) ) {
3122                         $cond = $this->makeList( $cond, self::LIST_AND );
3123                 }
3124
3125                 return " (CASE WHEN $cond THEN $trueVal ELSE $falseVal END) ";
3126         }
3127
3128         public function strreplace( $orig, $old, $new ) {
3129                 return "REPLACE({$orig}, {$old}, {$new})";
3130         }
3131
3132         public function getServerUptime() {
3133                 return 0;
3134         }
3135
3136         public function wasDeadlock() {
3137                 return false;
3138         }
3139
3140         public function wasLockTimeout() {
3141                 return false;
3142         }
3143
3144         public function wasConnectionLoss() {
3145                 return $this->wasConnectionError( $this->lastErrno() );
3146         }
3147
3148         public function wasReadOnlyError() {
3149                 return false;
3150         }
3151
3152         public function wasErrorReissuable() {
3153                 return (
3154                         $this->wasDeadlock() ||
3155                         $this->wasLockTimeout() ||
3156                         $this->wasConnectionLoss()
3157                 );
3158         }
3159
3160         /**
3161          * Do not use this method outside of Database/DBError classes
3162          *
3163          * @param int|string $errno
3164          * @return bool Whether the given query error was a connection drop
3165          */
3166         public function wasConnectionError( $errno ) {
3167                 return false;
3168         }
3169
3170         /**
3171          * @return bool Whether it is safe to assume the given error only caused statement rollback
3172          * @note This is for backwards compatibility for callers catching DBError exceptions in
3173          *   order to ignore problems like duplicate key errors or foriegn key violations
3174          * @since 1.31
3175          */
3176         protected function wasKnownStatementRollbackError() {
3177                 return false; // don't know; it could have caused a transaction rollback
3178         }
3179
3180         public function deadlockLoop() {
3181                 $args = func_get_args();
3182                 $function = array_shift( $args );
3183                 $tries = self::DEADLOCK_TRIES;
3184
3185                 $this->begin( __METHOD__ );
3186
3187                 $retVal = null;
3188                 /** @var Exception $e */
3189                 $e = null;
3190                 do {
3191                         try {
3192                                 $retVal = call_user_func_array( $function, $args );
3193                                 break;
3194                         } catch ( DBQueryError $e ) {
3195                                 if ( $this->wasDeadlock() ) {
3196                                         // Retry after a randomized delay
3197                                         usleep( mt_rand( self::DEADLOCK_DELAY_MIN, self::DEADLOCK_DELAY_MAX ) );
3198                                 } else {
3199                                         // Throw the error back up
3200                                         throw $e;
3201                                 }
3202                         }
3203                 } while ( --$tries > 0 );
3204
3205                 if ( $tries <= 0 ) {
3206                         // Too many deadlocks; give up
3207                         $this->rollback( __METHOD__ );
3208                         throw $e;
3209                 } else {
3210                         $this->commit( __METHOD__ );
3211
3212                         return $retVal;
3213                 }
3214         }
3215
3216         public function masterPosWait( DBMasterPos $pos, $timeout ) {
3217                 # Real waits are implemented in the subclass.
3218                 return 0;
3219         }
3220
3221         public function getReplicaPos() {
3222                 # Stub
3223                 return false;
3224         }
3225
3226         public function getMasterPos() {
3227                 # Stub
3228                 return false;
3229         }
3230
3231         public function serverIsReadOnly() {
3232                 return false;
3233         }
3234
3235         final public function onTransactionResolution( callable $callback, $fname = __METHOD__ ) {
3236                 if ( !$this->trxLevel ) {
3237                         throw new DBUnexpectedError( $this, "No transaction is active." );
3238                 }
3239                 $this->trxEndCallbacks[] = [ $callback, $fname, $this->currentAtomicSectionId() ];
3240         }
3241
3242         final public function onTransactionIdle( callable $callback, $fname = __METHOD__ ) {
3243                 if ( !$this->trxLevel && $this->getTransactionRoundId() ) {
3244                         // Start an implicit transaction similar to how query() does
3245                         $this->begin( __METHOD__, self::TRANSACTION_INTERNAL );
3246                         $this->trxAutomatic = true;
3247                 }
3248
3249                 $this->trxIdleCallbacks[] = [ $callback, $fname, $this->currentAtomicSectionId() ];
3250                 if ( !$this->trxLevel ) {
3251                         $this->runOnTransactionIdleCallbacks( self::TRIGGER_IDLE );
3252                 }
3253         }
3254
3255         final public function onTransactionPreCommitOrIdle( callable $callback, $fname = __METHOD__ ) {
3256                 if ( !$this->trxLevel && $this->getTransactionRoundId() ) {
3257                         // Start an implicit transaction similar to how query() does
3258                         $this->begin( __METHOD__, self::TRANSACTION_INTERNAL );
3259                         $this->trxAutomatic = true;
3260                 }
3261
3262                 if ( $this->trxLevel ) {
3263                         $this->trxPreCommitCallbacks[] = [ $callback, $fname, $this->currentAtomicSectionId() ];
3264                 } else {
3265                         // No transaction is active nor will start implicitly, so make one for this callback
3266                         $this->startAtomic( __METHOD__, self::ATOMIC_CANCELABLE );
3267                         try {
3268                                 call_user_func( $callback );
3269                                 $this->endAtomic( __METHOD__ );
3270                         } catch ( Exception $e ) {
3271                                 $this->cancelAtomic( __METHOD__ );
3272                                 throw $e;
3273                         }
3274                 }
3275         }
3276
3277         /**
3278          * @return AtomicSectionIdentifier|null ID of the topmost atomic section level
3279          */
3280         private function currentAtomicSectionId() {
3281                 if ( $this->trxLevel && $this->trxAtomicLevels ) {
3282                         $levelInfo = end( $this->trxAtomicLevels );
3283
3284                         return $levelInfo[1];
3285                 }
3286
3287                 return null;
3288         }
3289
3290         /**
3291          * @param AtomicSectionIdentifier $old
3292          * @param AtomicSectionIdentifier $new
3293          */
3294         private function reassignCallbacksForSection(
3295                 AtomicSectionIdentifier $old, AtomicSectionIdentifier $new
3296         ) {
3297                 foreach ( $this->trxPreCommitCallbacks as $key => $info ) {
3298                         if ( $info[2] === $old ) {
3299                                 $this->trxPreCommitCallbacks[$key][2] = $new;
3300                         }
3301                 }
3302                 foreach ( $this->trxIdleCallbacks as $key => $info ) {
3303                         if ( $info[2] === $old ) {
3304                                 $this->trxIdleCallbacks[$key][2] = $new;
3305                         }
3306                 }
3307                 foreach ( $this->trxEndCallbacks as $key => $info ) {
3308                         if ( $info[2] === $old ) {
3309                                 $this->trxEndCallbacks[$key][2] = $new;
3310                         }
3311                 }
3312         }
3313
3314         /**
3315          * @param AtomicSectionIdentifier[] $sectionIds ID of an actual savepoint
3316          * @throws UnexpectedValueException
3317          */
3318         private function modifyCallbacksForCancel( array $sectionIds ) {
3319                 // Cancel the "on commit" callbacks owned by this savepoint
3320                 $this->trxIdleCallbacks = array_filter(
3321                         $this->trxIdleCallbacks,
3322                         function ( $entry ) use ( $sectionIds ) {
3323                                 return !in_array( $entry[2], $sectionIds, true );
3324                         }
3325                 );
3326                 $this->trxPreCommitCallbacks = array_filter(
3327                         $this->trxPreCommitCallbacks,
3328                         function ( $entry ) use ( $sectionIds ) {
3329                                 return !in_array( $entry[2], $sectionIds, true );
3330                         }
3331                 );
3332                 // Make "on resolution" callbacks owned by this savepoint to perceive a rollback
3333                 foreach ( $this->trxEndCallbacks as $key => $entry ) {
3334                         if ( in_array( $entry[2], $sectionIds, true ) ) {
3335                                 $callback = $entry[0];
3336                                 $this->trxEndCallbacks[$key][0] = function () use ( $callback ) {
3337                                         return $callback( self::TRIGGER_ROLLBACK );
3338                                 };
3339                         }
3340                 }
3341         }
3342
3343         final public function setTransactionListener( $name, callable $callback = null ) {
3344                 if ( $callback ) {
3345                         $this->trxRecurringCallbacks[$name] = $callback;
3346                 } else {
3347                         unset( $this->trxRecurringCallbacks[$name] );
3348                 }
3349         }
3350
3351         /**
3352          * Whether to disable running of post-COMMIT/ROLLBACK callbacks
3353          *
3354          * This method should not be used outside of Database/LoadBalancer
3355          *
3356          * @param bool $suppress
3357          * @since 1.28
3358          */
3359         final public function setTrxEndCallbackSuppression( $suppress ) {
3360                 $this->trxEndCallbacksSuppressed = $suppress;
3361         }
3362
3363         /**
3364          * Actually run and consume any "on transaction idle/resolution" callbacks.
3365          *
3366          * This method should not be used outside of Database/LoadBalancer
3367          *
3368          * @param int $trigger IDatabase::TRIGGER_* constant
3369          * @since 1.20
3370          * @throws Exception
3371          */
3372         public function runOnTransactionIdleCallbacks( $trigger ) {
3373                 if ( $this->trxEndCallbacksSuppressed ) {
3374                         return;
3375                 }
3376
3377                 $autoTrx = $this->getFlag( self::DBO_TRX ); // automatic begin() enabled?
3378                 /** @var Exception $e */
3379                 $e = null; // first exception
3380                 do { // callbacks may add callbacks :)
3381                         $callbacks = array_merge(
3382                                 $this->trxIdleCallbacks,
3383                                 $this->trxEndCallbacks // include "transaction resolution" callbacks
3384                         );
3385                         $this->trxIdleCallbacks = []; // consumed (and recursion guard)
3386                         $this->trxEndCallbacks = []; // consumed (recursion guard)
3387                         foreach ( $callbacks as $callback ) {
3388                                 try {
3389                                         list( $phpCallback ) = $callback;
3390                                         $this->clearFlag( self::DBO_TRX ); // make each query its own transaction
3391                                         call_user_func_array( $phpCallback, [ $trigger ] );
3392                                         if ( $autoTrx ) {
3393                                                 $this->setFlag( self::DBO_TRX ); // restore automatic begin()
3394                                         } else {
3395                                                 $this->clearFlag( self::DBO_TRX ); // restore auto-commit
3396                                         }
3397                                 } catch ( Exception $ex ) {
3398                                         call_user_func( $this->errorLogger, $ex );
3399                                         $e = $e ?: $ex;
3400                                         // Some callbacks may use startAtomic/endAtomic, so make sure
3401                                         // their transactions are ended so other callbacks don't fail
3402                                         if ( $this->trxLevel() ) {
3403                                                 $this->rollback( __METHOD__, self::FLUSHING_INTERNAL );
3404                                         }
3405                                 }
3406                         }
3407                 } while ( count( $this->trxIdleCallbacks ) );
3408
3409                 if ( $e instanceof Exception ) {
3410                         throw $e; // re-throw any first exception
3411                 }
3412         }
3413
3414         /**
3415          * Actually run and consume any "on transaction pre-commit" callbacks.
3416          *
3417          * This method should not be used outside of Database/LoadBalancer
3418          *
3419          * @since 1.22
3420          * @throws Exception
3421          */
3422         public function runOnTransactionPreCommitCallbacks() {
3423                 $e = null; // first exception
3424                 do { // callbacks may add callbacks :)
3425                         $callbacks = $this->trxPreCommitCallbacks;
3426                         $this->trxPreCommitCallbacks = []; // consumed (and recursion guard)
3427                         foreach ( $callbacks as $callback ) {
3428                                 try {
3429                                         list( $phpCallback ) = $callback;
3430                                         call_user_func( $phpCallback );
3431                                 } catch ( Exception $ex ) {
3432                                         call_user_func( $this->errorLogger, $ex );
3433                                         $e = $e ?: $ex;
3434                                 }
3435                         }
3436                 } while ( count( $this->trxPreCommitCallbacks ) );
3437
3438                 if ( $e instanceof Exception ) {
3439                         throw $e; // re-throw any first exception
3440                 }
3441         }
3442
3443         /**
3444          * Actually run any "transaction listener" callbacks.
3445          *
3446          * This method should not be used outside of Database/LoadBalancer
3447          *
3448          * @param int $trigger IDatabase::TRIGGER_* constant
3449          * @throws Exception
3450          * @since 1.20
3451          */
3452         public function runTransactionListenerCallbacks( $trigger ) {
3453                 if ( $this->trxEndCallbacksSuppressed ) {
3454                         return;
3455                 }
3456
3457                 /** @var Exception $e */
3458                 $e = null; // first exception
3459
3460                 foreach ( $this->trxRecurringCallbacks as $phpCallback ) {
3461                         try {
3462                                 $phpCallback( $trigger, $this );
3463                         } catch ( Exception $ex ) {
3464                                 call_user_func( $this->errorLogger, $ex );
3465                                 $e = $e ?: $ex;
3466                         }
3467                 }
3468
3469                 if ( $e instanceof Exception ) {
3470                         throw $e; // re-throw any first exception
3471                 }
3472         }
3473
3474         /**
3475          * Create a savepoint
3476          *
3477          * This is used internally to implement atomic sections. It should not be
3478          * used otherwise.
3479          *
3480          * @since 1.31
3481          * @param string $identifier Identifier for the savepoint
3482          * @param string $fname Calling function name
3483          */
3484         protected function doSavepoint( $identifier, $fname ) {
3485                 $this->query( 'SAVEPOINT ' . $this->addIdentifierQuotes( $identifier ), $fname );
3486         }
3487
3488         /**
3489          * Release a savepoint
3490          *
3491          * This is used internally to implement atomic sections. It should not be
3492          * used otherwise.
3493          *
3494          * @since 1.31
3495          * @param string $identifier Identifier for the savepoint
3496          * @param string $fname Calling function name
3497          */
3498         protected function doReleaseSavepoint( $identifier, $fname ) {
3499                 $this->query( 'RELEASE SAVEPOINT ' . $this->addIdentifierQuotes( $identifier ), $fname );
3500         }
3501
3502         /**
3503          * Rollback to a savepoint
3504          *
3505          * This is used internally to implement atomic sections. It should not be
3506          * used otherwise.
3507          *
3508          * @since 1.31
3509          * @param string $identifier Identifier for the savepoint
3510          * @param string $fname Calling function name
3511          */
3512         protected function doRollbackToSavepoint( $identifier, $fname ) {
3513                 $this->query( 'ROLLBACK TO SAVEPOINT ' . $this->addIdentifierQuotes( $identifier ), $fname );
3514         }
3515
3516         /**
3517          * @param string $fname
3518          * @return string
3519          */
3520         private function nextSavepointId( $fname ) {
3521                 $savepointId = self::$SAVEPOINT_PREFIX . ++$this->trxAtomicCounter;
3522                 if ( strlen( $savepointId ) > 30 ) {
3523                         // 30 == Oracle's identifier length limit (pre 12c)
3524                         // With a 22 character prefix, that puts the highest number at 99999999.
3525                         throw new DBUnexpectedError(
3526                                 $this,
3527                                 'There have been an excessively large number of atomic sections in a transaction'
3528                                 . " started by $this->trxFname (at $fname)"
3529                         );
3530                 }
3531
3532                 return $savepointId;
3533         }
3534
3535         final public function startAtomic(
3536                 $fname = __METHOD__, $cancelable = self::ATOMIC_NOT_CANCELABLE
3537         ) {
3538                 $savepointId = $cancelable === self::ATOMIC_CANCELABLE ? self::$NOT_APPLICABLE : null;
3539
3540                 if ( !$this->trxLevel ) {
3541                         $this->begin( $fname, self::TRANSACTION_INTERNAL );
3542                         // If DBO_TRX is set, a series of startAtomic/endAtomic pairs will result
3543                         // in all changes being in one transaction to keep requests transactional.
3544                         if ( $this->getFlag( self::DBO_TRX ) ) {
3545                                 // Since writes could happen in between the topmost atomic sections as part
3546                                 // of the transaction, those sections will need savepoints.
3547                                 $savepointId = $this->nextSavepointId( $fname );
3548                                 $this->doSavepoint( $savepointId, $fname );
3549                         } else {
3550                                 $this->trxAutomaticAtomic = true;
3551                         }
3552                 } elseif ( $cancelable === self::ATOMIC_CANCELABLE ) {
3553                         $savepointId = $this->nextSavepointId( $fname );
3554                         $this->doSavepoint( $savepointId, $fname );
3555                 }
3556
3557                 $sectionId = new AtomicSectionIdentifier;
3558                 $this->trxAtomicLevels[] = [ $fname, $sectionId, $savepointId ];
3559
3560                 return $sectionId;
3561         }
3562
3563         final public function endAtomic( $fname = __METHOD__ ) {
3564                 if ( !$this->trxLevel || !$this->trxAtomicLevels ) {
3565                         throw new DBUnexpectedError( $this, "No atomic section is open (got $fname)." );
3566                 }
3567
3568                 // Check if the current section matches $fname
3569                 $pos = count( $this->trxAtomicLevels ) - 1;
3570                 list( $savedFname, $sectionId, $savepointId ) = $this->trxAtomicLevels[$pos];
3571
3572                 if ( $savedFname !== $fname ) {
3573                         throw new DBUnexpectedError(
3574                                 $this,
3575                                 "Invalid atomic section ended (got $fname but expected $savedFname)."
3576                         );
3577                 }
3578
3579                 // Remove the last section (no need to re-index the array)
3580                 array_pop( $this->trxAtomicLevels );
3581
3582                 if ( !$this->trxAtomicLevels && $this->trxAutomaticAtomic ) {
3583                         $this->commit( $fname, self::FLUSHING_INTERNAL );
3584                 } elseif ( $savepointId !== null && $savepointId !== self::$NOT_APPLICABLE ) {
3585                         $this->doReleaseSavepoint( $savepointId, $fname );
3586                 }
3587
3588                 // Hoist callback ownership for callbacks in the section that just ended;
3589                 // all callbacks should have an owner that is present in trxAtomicLevels.
3590                 $currentSectionId = $this->currentAtomicSectionId();
3591                 if ( $currentSectionId ) {
3592                         $this->reassignCallbacksForSection( $sectionId, $currentSectionId );
3593                 }
3594         }
3595
3596         final public function cancelAtomic(
3597                 $fname = __METHOD__, AtomicSectionIdentifier $sectionId = null
3598         ) {
3599                 if ( !$this->trxLevel || !$this->trxAtomicLevels ) {
3600                         throw new DBUnexpectedError( $this, "No atomic section is open (got $fname)." );
3601                 }
3602
3603                 if ( $sectionId !== null ) {
3604                         // Find the (last) section with the given $sectionId
3605                         $pos = -1;
3606                         foreach ( $this->trxAtomicLevels as $i => list( $asFname, $asId, $spId ) ) {
3607                                 if ( $asId === $sectionId ) {
3608                                         $pos = $i;
3609                                 }
3610                         }
3611                         if ( $pos < 0 ) {
3612                                 throw new DBUnexpectedError( "Atomic section not found (for $fname)" );
3613                         }
3614                         // Remove all descendant sections and re-index the array
3615                         $excisedIds = [];
3616                         $len = count( $this->trxAtomicLevels );
3617                         for ( $i = $pos + 1; $i < $len; ++$i ) {
3618                                 $excisedIds[] = $this->trxAtomicLevels[$i][1];
3619                         }
3620                         $this->trxAtomicLevels = array_slice( $this->trxAtomicLevels, 0, $pos + 1 );
3621                         $this->modifyCallbacksForCancel( $excisedIds );
3622                 }
3623
3624                 // Check if the current section matches $fname
3625                 $pos = count( $this->trxAtomicLevels ) - 1;
3626                 list( $savedFname, $savedSectionId, $savepointId ) = $this->trxAtomicLevels[$pos];
3627
3628                 if ( $savedFname !== $fname ) {
3629                         throw new DBUnexpectedError(
3630                                 $this,
3631                                 "Invalid atomic section ended (got $fname but expected $savedFname)."
3632                         );
3633                 }
3634
3635                 // Remove the last section (no need to re-index the array)
3636                 array_pop( $this->trxAtomicLevels );
3637                 $this->modifyCallbacksForCancel( [ $savedSectionId ] );
3638
3639                 if ( $savepointId !== null ) {
3640                         // Rollback the transaction to the state just before this atomic section
3641                         if ( $savepointId === self::$NOT_APPLICABLE ) {
3642                                 $this->rollback( $fname, self::FLUSHING_INTERNAL );
3643                         } else {
3644                                 $this->doRollbackToSavepoint( $savepointId, $fname );
3645                                 $this->trxStatus = self::STATUS_TRX_OK; // no exception; recovered
3646                                 $this->trxStatusIgnoredCause = null;
3647                         }
3648                 } elseif ( $this->trxStatus > self::STATUS_TRX_ERROR ) {
3649                         // Put the transaction into an error state if it's not already in one
3650                         $this->trxStatus = self::STATUS_TRX_ERROR;
3651                         $this->trxStatusCause = new DBUnexpectedError(
3652                                 $this,
3653                                 "Uncancelable atomic section canceled (got $fname)."
3654                         );
3655                 }
3656
3657                 $this->affectedRowCount = 0; // for the sake of consistency
3658         }
3659
3660         final public function doAtomicSection(
3661                 $fname, callable $callback, $cancelable = self::ATOMIC_NOT_CANCELABLE
3662         ) {
3663                 $sectionId = $this->startAtomic( $fname, $cancelable );
3664                 try {
3665                         $res = call_user_func_array( $callback, [ $this, $fname ] );
3666                 } catch ( Exception $e ) {
3667                         $this->cancelAtomic( $fname, $sectionId );
3668
3669                         throw $e;
3670                 }
3671                 $this->endAtomic( $fname );
3672
3673                 return $res;
3674         }
3675
3676         final public function begin( $fname = __METHOD__, $mode = self::TRANSACTION_EXPLICIT ) {
3677                 static $modes = [ self::TRANSACTION_EXPLICIT, self::TRANSACTION_INTERNAL ];
3678                 if ( !in_array( $mode, $modes, true ) ) {
3679                         throw new DBUnexpectedError( $this, "$fname: invalid mode parameter '$mode'." );
3680                 }
3681
3682                 // Protect against mismatched atomic section, transaction nesting, and snapshot loss
3683                 if ( $this->trxLevel ) {
3684                         if ( $this->trxAtomicLevels ) {
3685                                 $levels = $this->flatAtomicSectionList();
3686                                 $msg = "$fname: Got explicit BEGIN while atomic section(s) $levels are open.";
3687                                 throw new DBUnexpectedError( $this, $msg );
3688                         } elseif ( !$this->trxAutomatic ) {
3689                                 $msg = "$fname: Explicit transaction already active (from {$this->trxFname}).";
3690                                 throw new DBUnexpectedError( $this, $msg );
3691                         } else {
3692                                 $msg = "$fname: Implicit transaction already active (from {$this->trxFname}).";
3693                                 throw new DBUnexpectedError( $this, $msg );
3694                         }
3695                 } elseif ( $this->getFlag( self::DBO_TRX ) && $mode !== self::TRANSACTION_INTERNAL ) {
3696                         $msg = "$fname: Implicit transaction expected (DBO_TRX set).";
3697                         throw new DBUnexpectedError( $this, $msg );
3698                 }
3699
3700                 // Avoid fatals if close() was called
3701                 $this->assertOpen();
3702
3703                 $this->doBegin( $fname );
3704                 $this->trxStatus = self::STATUS_TRX_OK;
3705                 $this->trxStatusIgnoredCause = null;
3706                 $this->trxAtomicCounter = 0;
3707                 $this->trxTimestamp = microtime( true );
3708                 $this->trxFname = $fname;
3709                 $this->trxDoneWrites = false;
3710                 $this->trxAutomaticAtomic = false;
3711                 $this->trxAtomicLevels = [];
3712                 $this->trxShortId = sprintf( '%06x', mt_rand( 0, 0xffffff ) );
3713                 $this->trxWriteDuration = 0.0;
3714                 $this->trxWriteQueryCount = 0;
3715                 $this->trxWriteAffectedRows = 0;
3716                 $this->trxWriteAdjDuration = 0.0;
3717                 $this->trxWriteAdjQueryCount = 0;
3718                 $this->trxWriteCallers = [];
3719                 // First SELECT after BEGIN will establish the snapshot in REPEATABLE-READ.
3720                 // Get an estimate of the replication lag before any such queries.
3721                 $this->trxReplicaLag = null; // clear cached value first
3722                 $this->trxReplicaLag = $this->getApproximateLagStatus()['lag'];
3723                 // T147697: make explicitTrxActive() return true until begin() finishes. This way, no
3724                 // caller will think its OK to muck around with the transaction just because startAtomic()
3725                 // has not yet completed (e.g. setting trxAtomicLevels).
3726                 $this->trxAutomatic = ( $mode === self::TRANSACTION_INTERNAL );
3727         }
3728
3729         /**
3730          * Issues the BEGIN command to the database server.
3731          *
3732          * @see Database::begin()
3733          * @param string $fname
3734          */
3735         protected function doBegin( $fname ) {
3736                 $this->query( 'BEGIN', $fname );
3737                 $this->trxLevel = 1;
3738         }
3739
3740         final public function commit( $fname = __METHOD__, $flush = self::FLUSHING_ONE ) {
3741                 static $modes = [ self::FLUSHING_ONE, self::FLUSHING_ALL_PEERS, self::FLUSHING_INTERNAL ];
3742                 if ( !in_array( $flush, $modes, true ) ) {
3743                         throw new DBUnexpectedError( $this, "$fname: invalid flush parameter '$flush'." );
3744                 }
3745
3746                 if ( $this->trxLevel && $this->trxAtomicLevels ) {
3747                         // There are still atomic sections open; this cannot be ignored
3748                         $levels = $this->flatAtomicSectionList();
3749                         throw new DBUnexpectedError(
3750                                 $this,
3751                                 "$fname: Got COMMIT while atomic sections $levels are still open."
3752                         );
3753                 }
3754
3755                 if ( $flush === self::FLUSHING_INTERNAL || $flush === self::FLUSHING_ALL_PEERS ) {
3756                         if ( !$this->trxLevel ) {
3757                                 return; // nothing to do
3758                         } elseif ( !$this->trxAutomatic ) {
3759                                 throw new DBUnexpectedError(
3760                                         $this,
3761                                         "$fname: Flushing an explicit transaction, getting out of sync."
3762                                 );
3763                         }
3764                 } else {
3765                         if ( !$this->trxLevel ) {
3766                                 $this->queryLogger->error(
3767                                         "$fname: No transaction to commit, something got out of sync." );
3768                                 return; // nothing to do
3769                         } elseif ( $this->trxAutomatic ) {
3770                                 throw new DBUnexpectedError(
3771                                         $this,
3772                                         "$fname: Expected mass commit of all peer transactions (DBO_TRX set)."
3773                                 );
3774                         }
3775                 }
3776
3777                 // Avoid fatals if close() was called
3778                 $this->assertOpen();
3779
3780                 $this->runOnTransactionPreCommitCallbacks();
3781                 $writeTime = $this->pendingWriteQueryDuration( self::ESTIMATE_DB_APPLY );
3782                 $this->doCommit( $fname );
3783                 $this->trxStatus = self::STATUS_TRX_NONE;
3784                 if ( $this->trxDoneWrites ) {
3785                         $this->lastWriteTime = microtime( true );
3786                         $this->trxProfiler->transactionWritingOut(
3787                                 $this->server,
3788                                 $this->dbName,
3789                                 $this->trxShortId,
3790                                 $writeTime,
3791                                 $this->trxWriteAffectedRows
3792                         );
3793                 }
3794
3795                 $this->runOnTransactionIdleCallbacks( self::TRIGGER_COMMIT );
3796                 $this->runTransactionListenerCallbacks( self::TRIGGER_COMMIT );
3797         }
3798
3799         /**
3800          * Issues the COMMIT command to the database server.
3801          *
3802          * @see Database::commit()
3803          * @param string $fname
3804          */
3805         protected function doCommit( $fname ) {
3806                 if ( $this->trxLevel ) {
3807                         $this->query( 'COMMIT', $fname );
3808                         $this->trxLevel = 0;
3809                 }
3810         }
3811
3812         final public function rollback( $fname = __METHOD__, $flush = '' ) {
3813                 $trxActive = $this->trxLevel;
3814
3815                 if ( $flush !== self::FLUSHING_INTERNAL && $flush !== self::FLUSHING_ALL_PEERS ) {
3816                         if ( $this->getFlag( self::DBO_TRX ) ) {
3817                                 throw new DBUnexpectedError(
3818                                         $this,
3819                                         "$fname: Expected mass rollback of all peer transactions (DBO_TRX set)."
3820                                 );
3821                         }
3822                 }
3823
3824                 if ( $trxActive ) {
3825                         // Avoid fatals if close() was called
3826                         $this->assertOpen();
3827
3828                         $this->doRollback( $fname );
3829                         $this->trxStatus = self::STATUS_TRX_NONE;
3830                         $this->trxAtomicLevels = [];
3831                         if ( $this->trxDoneWrites ) {
3832                                 $this->trxProfiler->transactionWritingOut(
3833                                         $this->server,
3834                                         $this->dbName,
3835                                         $this->trxShortId
3836                                 );
3837                         }
3838                 }
3839
3840                 // Clear any commit-dependant callbacks. They might even be present
3841                 // only due to transaction rounds, with no SQL transaction being active
3842                 $this->trxIdleCallbacks = [];
3843                 $this->trxPreCommitCallbacks = [];
3844
3845                 if ( $trxActive ) {
3846                         try {
3847                                 $this->runOnTransactionIdleCallbacks( self::TRIGGER_ROLLBACK );
3848                         } catch ( Exception $e ) {
3849                                 // already logged; finish and let LoadBalancer move on during mass-rollback
3850                         }
3851                         try {
3852                                 $this->runTransactionListenerCallbacks( self::TRIGGER_ROLLBACK );
3853                         } catch ( Exception $e ) {
3854                                 // already logged; let LoadBalancer move on during mass-rollback
3855                         }
3856
3857                         $this->affectedRowCount = 0; // for the sake of consistency
3858                 }
3859         }
3860
3861         /**
3862          * Issues the ROLLBACK command to the database server.
3863          *
3864          * @see Database::rollback()
3865          * @param string $fname
3866          */
3867         protected function doRollback( $fname ) {
3868                 if ( $this->trxLevel ) {
3869                         # Disconnects cause rollback anyway, so ignore those errors
3870                         $ignoreErrors = true;
3871                         $this->query( 'ROLLBACK', $fname, $ignoreErrors );
3872                         $this->trxLevel = 0;
3873                 }
3874         }
3875
3876         public function flushSnapshot( $fname = __METHOD__ ) {
3877                 if ( $this->writesOrCallbacksPending() || $this->explicitTrxActive() ) {
3878                         // This only flushes transactions to clear snapshots, not to write data
3879                         $fnames = implode( ', ', $this->pendingWriteAndCallbackCallers() );
3880                         throw new DBUnexpectedError(
3881                                 $this,
3882                                 "$fname: Cannot flush snapshot because writes are pending ($fnames)."
3883                         );
3884                 }
3885
3886                 $this->commit( $fname, self::FLUSHING_INTERNAL );
3887         }
3888
3889         public function explicitTrxActive() {
3890                 return $this->trxLevel && ( $this->trxAtomicLevels || !$this->trxAutomatic );
3891         }
3892
3893         public function duplicateTableStructure(
3894                 $oldName, $newName, $temporary = false, $fname = __METHOD__
3895         ) {
3896                 throw new RuntimeException( __METHOD__ . ' is not implemented in descendant class' );
3897         }
3898
3899         public function listTables( $prefix = null, $fname = __METHOD__ ) {
3900                 throw new RuntimeException( __METHOD__ . ' is not implemented in descendant class' );
3901         }
3902
3903         public function listViews( $prefix = null, $fname = __METHOD__ ) {
3904                 throw new RuntimeException( __METHOD__ . ' is not implemented in descendant class' );
3905         }
3906
3907         public function timestamp( $ts = 0 ) {
3908                 $t = new ConvertibleTimestamp( $ts );
3909                 // Let errors bubble up to avoid putting garbage in the DB
3910                 return $t->getTimestamp( TS_MW );
3911         }
3912
3913         public function timestampOrNull( $ts = null ) {
3914                 if ( is_null( $ts ) ) {
3915                         return null;
3916                 } else {
3917                         return $this->timestamp( $ts );
3918                 }
3919         }
3920
3921         public function affectedRows() {
3922                 return ( $this->affectedRowCount === null )
3923                         ? $this->fetchAffectedRowCount() // default to driver value
3924                         : $this->affectedRowCount;
3925         }
3926
3927         /**
3928          * @return int Number of retrieved rows according to the driver
3929          */
3930         abstract protected function fetchAffectedRowCount();
3931
3932         /**
3933          * Take the result from a query, and wrap it in a ResultWrapper if
3934          * necessary. Boolean values are passed through as is, to indicate success
3935          * of write queries or failure.
3936          *
3937          * Once upon a time, Database::query() returned a bare MySQL result
3938          * resource, and it was necessary to call this function to convert it to
3939          * a wrapper. Nowadays, raw database objects are never exposed to external
3940          * callers, so this is unnecessary in external code.
3941          *
3942          * @param bool|ResultWrapper|resource|object $result
3943          * @return bool|ResultWrapper
3944          */
3945         protected function resultObject( $result ) {
3946                 if ( !$result ) {
3947                         return false;
3948                 } elseif ( $result instanceof ResultWrapper ) {
3949                         return $result;
3950                 } elseif ( $result === true ) {
3951                         // Successful write query
3952                         return $result;
3953                 } else {
3954                         return new ResultWrapper( $this, $result );
3955                 }
3956         }
3957
3958         public function ping( &$rtt = null ) {
3959                 // Avoid hitting the server if it was hit recently
3960                 if ( $this->isOpen() && ( microtime( true ) - $this->lastPing ) < self::PING_TTL ) {
3961                         if ( !func_num_args() || $this->rttEstimate > 0 ) {
3962                                 $rtt = $this->rttEstimate;
3963                                 return true; // don't care about $rtt
3964                         }
3965                 }
3966
3967                 // This will reconnect if possible or return false if not
3968                 $this->clearFlag( self::DBO_TRX, self::REMEMBER_PRIOR );
3969                 $ok = ( $this->query( self::PING_QUERY, __METHOD__, true ) !== false );
3970                 $this->restoreFlags( self::RESTORE_PRIOR );
3971
3972                 if ( $ok ) {
3973                         $rtt = $this->rttEstimate;
3974                 }
3975
3976                 return $ok;
3977         }
3978
3979         /**
3980          * Close any existing (dead) database connection and open a new connection
3981          *
3982          * @param string $fname
3983          * @return bool True if new connection is opened successfully, false if error
3984          */
3985         protected function replaceLostConnection( $fname ) {
3986                 $this->closeConnection();
3987                 $this->opened = false;
3988                 $this->conn = false;
3989                 try {
3990                         $this->open( $this->server, $this->user, $this->password, $this->dbName );
3991                         $this->lastPing = microtime( true );
3992                         $ok = true;
3993
3994                         $this->connLogger->warning(
3995                                 $fname . ': lost connection to {dbserver}; reconnected',
3996                                 [
3997                                         'dbserver' => $this->getServer(),
3998                                         'trace' => ( new RuntimeException() )->getTraceAsString()
3999                                 ]
4000                         );
4001                 } catch ( DBConnectionError $e ) {
4002                         $ok = false;
4003
4004                         $this->connLogger->error(
4005                                 $fname . ': lost connection to {dbserver} permanently',
4006                                 [ 'dbserver' => $this->getServer() ]
4007                         );
4008                 }
4009
4010                 $this->handleSessionLoss();
4011
4012                 return $ok;
4013         }
4014
4015         public function getSessionLagStatus() {
4016                 return $this->getRecordedTransactionLagStatus() ?: $this->getApproximateLagStatus();
4017         }
4018
4019         /**
4020          * Get the replica DB lag when the current transaction started
4021          *
4022          * This is useful when transactions might use snapshot isolation
4023          * (e.g. REPEATABLE-READ in innodb), so the "real" lag of that data
4024          * is this lag plus transaction duration. If they don't, it is still
4025          * safe to be pessimistic. This returns null if there is no transaction.
4026          *
4027          * This returns null if the lag status for this transaction was not yet recorded.
4028          *
4029          * @return array|null ('lag': seconds or false on error, 'since': UNIX timestamp of BEGIN)
4030          * @since 1.27
4031          */
4032         final protected function getRecordedTransactionLagStatus() {
4033                 return ( $this->trxLevel && $this->trxReplicaLag !== null )
4034                         ? [ 'lag' => $this->trxReplicaLag, 'since' => $this->trxTimestamp() ]
4035                         : null;
4036         }
4037
4038         /**
4039          * Get a replica DB lag estimate for this server
4040          *
4041          * @return array ('lag': seconds or false on error, 'since': UNIX timestamp of estimate)
4042          * @since 1.27
4043          */
4044         protected function getApproximateLagStatus() {
4045                 return [
4046                         'lag'   => $this->getLBInfo( 'replica' ) ? $this->getLag() : 0,
4047                         'since' => microtime( true )
4048                 ];
4049         }
4050
4051         /**
4052          * Merge the result of getSessionLagStatus() for several DBs
4053          * using the most pessimistic values to estimate the lag of
4054          * any data derived from them in combination
4055          *
4056          * This is information is useful for caching modules
4057          *
4058          * @see WANObjectCache::set()
4059          * @see WANObjectCache::getWithSetCallback()
4060          *
4061          * @param IDatabase $db1
4062          * @param IDatabase $db2 [optional]
4063          * @return array Map of values:
4064          *   - lag: highest lag of any of the DBs or false on error (e.g. replication stopped)
4065          *   - since: oldest UNIX timestamp of any of the DB lag estimates
4066          *   - pending: whether any of the DBs have uncommitted changes
4067          * @throws DBError
4068          * @since 1.27
4069          */
4070         public static function getCacheSetOptions( IDatabase $db1, IDatabase $db2 = null ) {
4071                 $res = [ 'lag' => 0, 'since' => INF, 'pending' => false ];
4072                 foreach ( func_get_args() as $db ) {
4073                         /** @var IDatabase $db */
4074                         $status = $db->getSessionLagStatus();
4075                         if ( $status['lag'] === false ) {
4076                                 $res['lag'] = false;
4077                         } elseif ( $res['lag'] !== false ) {
4078                                 $res['lag'] = max( $res['lag'], $status['lag'] );
4079                         }
4080                         $res['since'] = min( $res['since'], $status['since'] );
4081                         $res['pending'] = $res['pending'] ?: $db->writesPending();
4082                 }
4083
4084                 return $res;
4085         }
4086
4087         public function getLag() {
4088                 return 0;
4089         }
4090
4091         public function maxListLen() {
4092                 return 0;
4093         }
4094
4095         public function encodeBlob( $b ) {
4096                 return $b;
4097         }
4098
4099         public function decodeBlob( $b ) {
4100                 if ( $b instanceof Blob ) {
4101                         $b = $b->fetch();
4102                 }
4103                 return $b;
4104         }
4105
4106         public function setSessionOptions( array $options ) {
4107         }
4108
4109         public function sourceFile(
4110                 $filename,
4111                 callable $lineCallback = null,
4112                 callable $resultCallback = null,
4113                 $fname = false,
4114                 callable $inputCallback = null
4115         ) {
4116                 Wikimedia\suppressWarnings();
4117                 $fp = fopen( $filename, 'r' );
4118                 Wikimedia\restoreWarnings();
4119
4120                 if ( false === $fp ) {
4121                         throw new RuntimeException( "Could not open \"{$filename}\".\n" );
4122                 }
4123
4124                 if ( !$fname ) {
4125                         $fname = __METHOD__ . "( $filename )";
4126                 }
4127
4128                 try {
4129                         $error = $this->sourceStream(
4130                                 $fp, $lineCallback, $resultCallback, $fname, $inputCallback );
4131                 } catch ( Exception $e ) {
4132                         fclose( $fp );
4133                         throw $e;
4134                 }
4135
4136                 fclose( $fp );
4137
4138                 return $error;
4139         }
4140
4141         public function setSchemaVars( $vars ) {
4142                 $this->schemaVars = $vars;
4143         }
4144
4145         public function sourceStream(
4146                 $fp,
4147                 callable $lineCallback = null,
4148                 callable $resultCallback = null,
4149                 $fname = __METHOD__,
4150                 callable $inputCallback = null
4151         ) {
4152                 $delimiterReset = new ScopedCallback(
4153                         function ( $delimiter ) {
4154                                 $this->delimiter = $delimiter;
4155                         },
4156                         [ $this->delimiter ]
4157                 );
4158                 $cmd = '';
4159
4160                 while ( !feof( $fp ) ) {
4161                         if ( $lineCallback ) {
4162                                 call_user_func( $lineCallback );
4163                         }
4164
4165                         $line = trim( fgets( $fp ) );
4166
4167                         if ( $line == '' ) {
4168                                 continue;
4169                         }
4170
4171                         if ( '-' == $line[0] && '-' == $line[1] ) {
4172                                 continue;
4173                         }
4174
4175                         if ( $cmd != '' ) {
4176                                 $cmd .= ' ';
4177                         }
4178
4179                         $done = $this->streamStatementEnd( $cmd, $line );
4180
4181                         $cmd .= "$line\n";
4182
4183                         if ( $done || feof( $fp ) ) {
4184                                 $cmd = $this->replaceVars( $cmd );
4185
4186                                 if ( $inputCallback ) {
4187                                         $callbackResult = call_user_func( $inputCallback, $cmd );
4188
4189                                         if ( is_string( $callbackResult ) || !$callbackResult ) {
4190                                                 $cmd = $callbackResult;
4191                                         }
4192                                 }
4193
4194                                 if ( $cmd ) {
4195                                         $res = $this->query( $cmd, $fname );
4196
4197                                         if ( $resultCallback ) {
4198                                                 call_user_func( $resultCallback, $res, $this );
4199                                         }
4200
4201                                         if ( false === $res ) {
4202                                                 $err = $this->lastError();
4203
4204                                                 return "Query \"{$cmd}\" failed with error code \"$err\".\n";
4205                                         }
4206                                 }
4207                                 $cmd = '';
4208                         }
4209                 }
4210
4211                 ScopedCallback::consume( $delimiterReset );
4212                 return true;
4213         }
4214
4215         /**
4216          * Called by sourceStream() to check if we've reached a statement end
4217          *
4218          * @param string &$sql SQL assembled so far
4219          * @param string &$newLine New line about to be added to $sql
4220          * @return bool Whether $newLine contains end of the statement
4221          */
4222         public function streamStatementEnd( &$sql, &$newLine ) {
4223                 if ( $this->delimiter ) {
4224                         $prev = $newLine;
4225                         $newLine = preg_replace(
4226                                 '/' . preg_quote( $this->delimiter, '/' ) . '$/', '', $newLine );
4227                         if ( $newLine != $prev ) {
4228                                 return true;
4229                         }
4230                 }
4231
4232                 return false;
4233         }
4234
4235         /**
4236          * Database independent variable replacement. Replaces a set of variables
4237          * in an SQL statement with their contents as given by $this->getSchemaVars().
4238          *
4239          * Supports '{$var}' `{$var}` and / *$var* / (without the spaces) style variables.
4240          *
4241          * - '{$var}' should be used for text and is passed through the database's
4242          *   addQuotes method.
4243          * - `{$var}` should be used for identifiers (e.g. table and database names).
4244          *   It is passed through the database's addIdentifierQuotes method which
4245          *   can be overridden if the database uses something other than backticks.
4246          * - / *_* / or / *$wgDBprefix* / passes the name that follows through the
4247          *   database's tableName method.
4248          * - / *i* / passes the name that follows through the database's indexName method.
4249          * - In all other cases, / *$var* / is left unencoded. Except for table options,
4250          *   its use should be avoided. In 1.24 and older, string encoding was applied.
4251          *
4252          * @param string $ins SQL statement to replace variables in
4253          * @return string The new SQL statement with variables replaced
4254          */
4255         protected function replaceVars( $ins ) {
4256                 $vars = $this->getSchemaVars();
4257                 return preg_replace_callback(
4258                         '!
4259                                 /\* (\$wgDBprefix|[_i]) \*/ (\w*) | # 1-2. tableName, indexName
4260                                 \'\{\$ (\w+) }\'                  | # 3. addQuotes
4261                                 `\{\$ (\w+) }`                    | # 4. addIdentifierQuotes
4262                                 /\*\$ (\w+) \*/                     # 5. leave unencoded
4263                         !x',
4264                         function ( $m ) use ( $vars ) {
4265                                 // Note: Because of <https://bugs.php.net/bug.php?id=51881>,
4266                                 // check for both nonexistent keys *and* the empty string.
4267                                 if ( isset( $m[1] ) && $m[1] !== '' ) {
4268                                         if ( $m[1] === 'i' ) {
4269                                                 return $this->indexName( $m[2] );
4270                                         } else {
4271                                                 return $this->tableName( $m[2] );
4272                                         }
4273                                 } elseif ( isset( $m[3] ) && $m[3] !== '' && array_key_exists( $m[3], $vars ) ) {
4274                                         return $this->addQuotes( $vars[$m[3]] );
4275                                 } elseif ( isset( $m[4] ) && $m[4] !== '' && array_key_exists( $m[4], $vars ) ) {
4276                                         return $this->addIdentifierQuotes( $vars[$m[4]] );
4277                                 } elseif ( isset( $m[5] ) && $m[5] !== '' && array_key_exists( $m[5], $vars ) ) {
4278                                         return $vars[$m[5]];
4279                                 } else {
4280                                         return $m[0];
4281                                 }
4282                         },
4283                         $ins
4284                 );
4285         }
4286
4287         /**
4288          * Get schema variables. If none have been set via setSchemaVars(), then
4289          * use some defaults from the current object.
4290          *
4291          * @return array
4292          */
4293         protected function getSchemaVars() {
4294                 if ( $this->schemaVars ) {
4295                         return $this->schemaVars;
4296                 } else {
4297                         return $this->getDefaultSchemaVars();
4298                 }
4299         }
4300
4301         /**
4302          * Get schema variables to use if none have been set via setSchemaVars().
4303          *
4304          * Override this in derived classes to provide variables for tables.sql
4305          * and SQL patch files.
4306          *
4307          * @return array
4308          */
4309         protected function getDefaultSchemaVars() {
4310                 return [];
4311         }
4312
4313         public function lockIsFree( $lockName, $method ) {
4314                 // RDBMs methods for checking named locks may or may not count this thread itself.
4315                 // In MySQL, IS_FREE_LOCK() returns 0 if the thread already has the lock. This is
4316                 // the behavior choosen by the interface for this method.
4317                 return !isset( $this->namedLocksHeld[$lockName] );
4318         }
4319
4320         public function lock( $lockName, $method, $timeout = 5 ) {
4321                 $this->namedLocksHeld[$lockName] = 1;
4322
4323                 return true;
4324         }
4325
4326         public function unlock( $lockName, $method ) {
4327                 unset( $this->namedLocksHeld[$lockName] );
4328
4329                 return true;
4330         }
4331
4332         public function getScopedLockAndFlush( $lockKey, $fname, $timeout ) {
4333                 if ( $this->writesOrCallbacksPending() ) {
4334                         // This only flushes transactions to clear snapshots, not to write data
4335                         $fnames = implode( ', ', $this->pendingWriteAndCallbackCallers() );
4336                         throw new DBUnexpectedError(
4337                                 $this,
4338                                 "$fname: Cannot flush pre-lock snapshot because writes are pending ($fnames)."
4339                         );
4340                 }
4341
4342                 if ( !$this->lock( $lockKey, $fname, $timeout ) ) {
4343                         return null;
4344                 }
4345
4346                 $unlocker = new ScopedCallback( function () use ( $lockKey, $fname ) {
4347                         if ( $this->trxLevel() ) {
4348                                 // There is a good chance an exception was thrown, causing any early return
4349                                 // from the caller. Let any error handler get a chance to issue rollback().
4350                                 // If there isn't one, let the error bubble up and trigger server-side rollback.
4351                                 $this->onTransactionResolution(
4352                                         function () use ( $lockKey, $fname ) {
4353                                                 $this->unlock( $lockKey, $fname );
4354                                         },
4355                                         $fname
4356                                 );
4357                         } else {
4358                                 $this->unlock( $lockKey, $fname );
4359                         }
4360                 } );
4361
4362                 $this->commit( $fname, self::FLUSHING_INTERNAL );
4363
4364                 return $unlocker;
4365         }
4366
4367         public function namedLocksEnqueue() {
4368                 return false;
4369         }
4370
4371         public function tableLocksHaveTransactionScope() {
4372                 return true;
4373         }
4374
4375         final public function lockTables( array $read, array $write, $method ) {
4376                 if ( $this->writesOrCallbacksPending() ) {
4377                         throw new DBUnexpectedError( $this, "Transaction writes or callbacks still pending." );
4378                 }
4379
4380                 if ( $this->tableLocksHaveTransactionScope() ) {
4381                         $this->startAtomic( $method );
4382                 }
4383
4384                 return $this->doLockTables( $read, $write, $method );
4385         }
4386
4387         /**
4388          * Helper function for lockTables() that handles the actual table locking
4389          *
4390          * @param array $read Array of tables to lock for read access
4391          * @param array $write Array of tables to lock for write access
4392          * @param string $method Name of caller
4393          * @return true
4394          */
4395         protected function doLockTables( array $read, array $write, $method ) {
4396                 return true;
4397         }
4398
4399         final public function unlockTables( $method ) {
4400                 if ( $this->tableLocksHaveTransactionScope() ) {
4401                         $this->endAtomic( $method );
4402
4403                         return true; // locks released on COMMIT/ROLLBACK
4404                 }
4405
4406                 return $this->doUnlockTables( $method );
4407         }
4408
4409         /**
4410          * Helper function for unlockTables() that handles the actual table unlocking
4411          *
4412          * @param string $method Name of caller
4413          * @return true
4414          */
4415         protected function doUnlockTables( $method ) {
4416                 return true;
4417         }
4418
4419         /**
4420          * Delete a table
4421          * @param string $tableName
4422          * @param string $fName
4423          * @return bool|ResultWrapper
4424          * @since 1.18
4425          */
4426         public function dropTable( $tableName, $fName = __METHOD__ ) {
4427                 if ( !$this->tableExists( $tableName, $fName ) ) {
4428                         return false;
4429                 }
4430                 $sql = "DROP TABLE " . $this->tableName( $tableName ) . " CASCADE";
4431
4432                 return $this->query( $sql, $fName );
4433         }
4434
4435         public function getInfinity() {
4436                 return 'infinity';
4437         }
4438
4439         public function encodeExpiry( $expiry ) {
4440                 return ( $expiry == '' || $expiry == 'infinity' || $expiry == $this->getInfinity() )
4441                         ? $this->getInfinity()
4442                         : $this->timestamp( $expiry );
4443         }
4444
4445         public function decodeExpiry( $expiry, $format = TS_MW ) {
4446                 if ( $expiry == '' || $expiry == 'infinity' || $expiry == $this->getInfinity() ) {
4447                         return 'infinity';
4448                 }
4449
4450                 return ConvertibleTimestamp::convert( $format, $expiry );
4451         }
4452
4453         public function setBigSelects( $value = true ) {
4454                 // no-op
4455         }
4456
4457         public function isReadOnly() {
4458                 return ( $this->getReadOnlyReason() !== false );
4459         }
4460
4461         /**
4462          * @return string|bool Reason this DB is read-only or false if it is not
4463          */
4464         protected function getReadOnlyReason() {
4465                 $reason = $this->getLBInfo( 'readOnlyReason' );
4466
4467                 return is_string( $reason ) ? $reason : false;
4468         }
4469
4470         public function setTableAliases( array $aliases ) {
4471                 $this->tableAliases = $aliases;
4472         }
4473
4474         public function setIndexAliases( array $aliases ) {
4475                 $this->indexAliases = $aliases;
4476         }
4477
4478         /**
4479          * Get the underlying binding connection handle
4480          *
4481          * Makes sure the connection resource is set (disconnects and ping() failure can unset it).
4482          * This catches broken callers than catch and ignore disconnection exceptions.
4483          * Unlike checking isOpen(), this is safe to call inside of open().
4484          *
4485          * @return mixed
4486          * @throws DBUnexpectedError
4487          * @since 1.26
4488          */
4489         protected function getBindingHandle() {
4490                 if ( !$this->conn ) {
4491                         throw new DBUnexpectedError(
4492                                 $this,
4493                                 'DB connection was already closed or the connection dropped.'
4494                         );
4495                 }
4496
4497                 return $this->conn;
4498         }
4499
4500         /**
4501          * @since 1.19
4502          * @return string
4503          */
4504         public function __toString() {
4505                 return (string)$this->conn;
4506         }
4507
4508         /**
4509          * Make sure that copies do not share the same client binding handle
4510          * @throws DBConnectionError
4511          */
4512         public function __clone() {
4513                 $this->connLogger->warning(
4514                         "Cloning " . static::class . " is not recomended; forking connection:\n" .
4515                         ( new RuntimeException() )->getTraceAsString()
4516                 );
4517
4518                 if ( $this->isOpen() ) {
4519                         // Open a new connection resource without messing with the old one
4520                         $this->opened = false;
4521                         $this->conn = false;
4522                         $this->trxEndCallbacks = []; // don't copy
4523                         $this->handleSessionLoss(); // no trx or locks anymore
4524                         $this->open( $this->server, $this->user, $this->password, $this->dbName );
4525                         $this->lastPing = microtime( true );
4526                 }
4527         }
4528
4529         /**
4530          * Called by serialize. Throw an exception when DB connection is serialized.
4531          * This causes problems on some database engines because the connection is
4532          * not restored on unserialize.
4533          */
4534         public function __sleep() {
4535                 throw new RuntimeException( 'Database serialization may cause problems, since ' .
4536                         'the connection is not restored on wakeup.' );
4537         }
4538
4539         /**
4540          * Run a few simple sanity checks and close dangling connections
4541          */
4542         public function __destruct() {
4543                 if ( $this->trxLevel && $this->trxDoneWrites ) {
4544                         trigger_error( "Uncommitted DB writes (transaction from {$this->trxFname})." );
4545                 }
4546
4547                 $danglingWriters = $this->pendingWriteAndCallbackCallers();
4548                 if ( $danglingWriters ) {
4549                         $fnames = implode( ', ', $danglingWriters );
4550                         trigger_error( "DB transaction writes or callbacks still pending ($fnames)." );
4551                 }
4552
4553                 if ( $this->conn ) {
4554                         // Avoid connection leaks for sanity. Normally, resources close at script completion.
4555                         // The connection might already be closed in zend/hhvm by now, so suppress warnings.
4556                         Wikimedia\suppressWarnings();
4557                         $this->closeConnection();
4558                         Wikimedia\restoreWarnings();
4559                         $this->conn = false;
4560                         $this->opened = false;
4561                 }
4562         }
4563 }
4564
4565 class_alias( Database::class, 'DatabaseBase' ); // b/c for old name
4566 class_alias( Database::class, 'Database' ); // b/c global alias