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