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