dcb784311b
When $wgMainCache is CACHE_ANYTHING, recursion proceeds via LoadBalancer::isPrimaryRunningReadOnly() until the DB server hits its maximum connection limit. The try/catch blocks in ServiceWiring were no longer effectively preventing this. So, inspect the configuration to detect whether the main cache type will be CACHE_DB, without actually instantiating it. Bug: T334970 Change-Id: Ibdbc19c45eb20bb85df720669f7ce1d50e3656ff
397 lines
13 KiB
PHP
397 lines
13 KiB
PHP
<?php
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/**
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* Functions to get cache objects.
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*
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* This program is free software; you can redistribute it and/or modify
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* it under the terms of the GNU General Public License as published by
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* the Free Software Foundation; either version 2 of the License, or
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* (at your option) any later version.
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*
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* This program is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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* GNU General Public License for more details.
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*
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* You should have received a copy of the GNU General Public License along
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* with this program; if not, write to the Free Software Foundation, Inc.,
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* 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
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* http://www.gnu.org/copyleft/gpl.html
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*
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* @file
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* @ingroup Cache
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*/
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use MediaWiki\Logger\LoggerFactory;
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use MediaWiki\MainConfigNames;
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use MediaWiki\MediaWikiServices;
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use MediaWiki\WikiMap\WikiMap;
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/**
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* Functions to get cache objects
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*
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* The word "cache" has two main dictionary meanings, and both
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* are used in this factory class. They are:
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*
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* - a) Cache (the computer science definition).
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* A place to store copies or computations on existing data for
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* higher access speeds.
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* - b) Storage.
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* A place to store lightweight data that is not canonically
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* stored anywhere else (e.g. a "hoard" of objects).
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*
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* Primary entry points:
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*
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* - ObjectCache::getLocalServerInstance( $fallbackType )
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* Purpose: Memory cache for very hot keys.
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* Stored only on the individual web server (typically APC or APCu for web requests,
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* and EmptyBagOStuff in CLI mode).
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* Not replicated to the other servers.
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*
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* - ObjectCache::getLocalClusterInstance()
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* Purpose: Memory storage for per-cluster coordination and tracking.
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* A typical use case would be a rate limit counter or cache regeneration mutex.
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* Stored centrally within the local data-center. Not replicated to other DCs.
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* Configured by $wgMainCacheType.
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*
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* - ObjectCache::getInstance( $cacheType )
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* Purpose: Special cases (like tiered memory/disk caches).
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* Get a specific cache type by key in $wgObjectCaches.
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*
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* All the above BagOStuff cache instances have their makeKey()
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* method scoped to the *current* wiki ID. Use makeGlobalKey() to avoid this scoping
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* when using keys that need to be shared amongst wikis.
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*
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* @ingroup Cache
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*/
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class ObjectCache {
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/** @var BagOStuff[] Map of (id => BagOStuff) */
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public static $instances = [];
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/**
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* @internal for ObjectCacheTest
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* @var string
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*/
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public static $localServerCacheClass;
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/**
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* Get a cached instance of the specified type of cache object.
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*
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* @param string|int $id A key in $wgObjectCaches.
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* @return BagOStuff
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*/
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public static function getInstance( $id ) {
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if ( !isset( self::$instances[$id] ) ) {
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self::$instances[$id] = self::newFromId( $id );
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}
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return self::$instances[$id];
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}
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/**
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* Create a new cache object of the specified type.
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*
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* @param string|int $id A key in $wgObjectCaches.
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* @return BagOStuff
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* @throws InvalidArgumentException
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*/
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private static function newFromId( $id ) {
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global $wgObjectCaches;
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if ( !isset( $wgObjectCaches[$id] ) ) {
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// Always recognize these ones
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if ( $id === CACHE_NONE ) {
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return new EmptyBagOStuff();
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} elseif ( $id === CACHE_HASH ) {
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return new HashBagOStuff();
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}
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throw new InvalidArgumentException( "Invalid object cache type \"$id\" requested. " .
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"It is not present in \$wgObjectCaches." );
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}
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return self::newFromParams( $wgObjectCaches[$id] );
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}
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/**
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* Get the default keyspace for this wiki.
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*
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* This is either the value of the `CachePrefix` configuration variable,
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* or (if the former is unset) the `DBname` configuration variable, with
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* `DBprefix` (if defined).
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*
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* @return string
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*/
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private static function getDefaultKeyspace() {
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global $wgCachePrefix;
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$keyspace = $wgCachePrefix;
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if ( is_string( $keyspace ) && $keyspace !== '' ) {
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return $keyspace;
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}
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return WikiMap::getCurrentWikiDbDomain()->getId();
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}
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/**
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* Create a new cache object from parameters.
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*
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* @param array $params Must have 'factory' or 'class' property.
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* - factory: Callback passed $params that returns BagOStuff.
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* - class: BagOStuff subclass constructed with $params.
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* - loggroup: Alias to set 'logger' key with LoggerFactory group.
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* - .. Other parameters passed to factory or class.
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* @param MediaWikiServices|null $services [internal]
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* @return BagOStuff
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*/
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public static function newFromParams( array $params, MediaWikiServices $services = null ) {
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$services ??= MediaWikiServices::getInstance();
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$conf = $services->getMainConfig();
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// Apply default parameters and resolve the logger instance
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$params += [
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'logger' => LoggerFactory::getInstance( $params['loggroup'] ?? 'objectcache' ),
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'keyspace' => self::getDefaultKeyspace(),
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'asyncHandler' => [ DeferredUpdates::class, 'addCallableUpdate' ],
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'reportDupes' => true,
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'stats' => $services->getStatsdDataFactory(),
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];
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if ( isset( $params['factory'] ) ) {
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$args = $params['args'] ?? [ $params ];
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return call_user_func( $params['factory'], ...$args );
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}
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if ( !isset( $params['class'] ) ) {
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throw new InvalidArgumentException(
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'No "factory" nor "class" provided; got "' . print_r( $params, true ) . '"'
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);
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}
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$class = $params['class'];
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// Normalization and DI for SqlBagOStuff
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if ( is_a( $class, SqlBagOStuff::class, true ) ) {
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if ( isset( $params['globalKeyLB'] ) ) {
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throw new InvalidArgumentException(
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'globalKeyLB in $wgObjectCaches is no longer supported' );
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}
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if ( isset( $params['server'] ) && !isset( $params['servers'] ) ) {
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$params['servers'] = [ $params['server'] ];
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unset( $params['server'] );
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}
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if ( isset( $params['servers'] ) ) {
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// In the past it was not required to set 'dbDirectory' in $wgObjectCaches
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foreach ( $params['servers'] as &$server ) {
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if ( $server['type'] === 'sqlite' && !isset( $server['dbDirectory'] ) ) {
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$server['dbDirectory'] = $conf->get( MainConfigNames::SQLiteDataDir );
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}
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}
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} elseif ( isset( $params['cluster'] ) ) {
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$cluster = $params['cluster'];
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$params['loadBalancerCallback'] = static function () use ( $services, $cluster ) {
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return $services->getDBLoadBalancerFactory()->getExternalLB( $cluster );
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};
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$params += [ 'dbDomain' => false ];
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} else {
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$params['loadBalancerCallback'] = static function () use ( $services ) {
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return $services->getDBLoadBalancer();
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};
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$params += [ 'dbDomain' => false ];
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}
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$params += [ 'writeBatchSize' => $conf->get( MainConfigNames::UpdateRowsPerQuery ) ];
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}
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// Normalization and DI for MemcachedBagOStuff
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if ( is_subclass_of( $class, MemcachedBagOStuff::class ) ) {
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$params += [
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'servers' => $conf->get( MainConfigNames::MemCachedServers ),
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'persistent' => $conf->get( MainConfigNames::MemCachedPersistent ),
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'timeout' => $conf->get( MainConfigNames::MemCachedTimeout ),
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];
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}
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// Normalization and DI for MultiWriteBagOStuff
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if ( is_a( $class, MultiWriteBagOStuff::class, true ) ) {
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// Phan warns about foreach with non-array because it
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// thinks any key can be Closure|IBufferingStatsdDataFactory
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'@phan-var array{caches:array[]} $params';
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foreach ( $params['caches'] ?? [] as $i => $cacheInfo ) {
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// Ensure logger, keyspace, asyncHandler, etc are injected just as if
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// one of these was configured without MultiWriteBagOStuff.
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$params['caches'][$i] = self::newFromParams( $cacheInfo, $services );
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}
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}
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return new $class( $params );
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}
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/**
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* Factory function for CACHE_ANYTHING (referenced by configuration)
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*
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* CACHE_ANYTHING means that stuff has to be cached, not caching is not an option.
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* If a caching method is configured for any of the main caches ($wgMainCacheType,
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* $wgMessageCacheType, $wgParserCacheType), then CACHE_ANYTHING will effectively
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* be an alias to the configured cache choice for that.
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* If no cache choice is configured (by default $wgMainCacheType is CACHE_NONE),
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* then CACHE_ANYTHING will forward to CACHE_DB.
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*
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* @param array $params
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* @return BagOStuff
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*/
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public static function newAnything( $params ) {
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return self::getInstance( self::getAnythingId() );
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}
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/**
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* Get the ID that will be used for CACHE_ANYTHING
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* @return string|int
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*/
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private static function getAnythingId() {
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global $wgMainCacheType, $wgMessageCacheType, $wgParserCacheType;
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$candidates = [ $wgMainCacheType, $wgMessageCacheType, $wgParserCacheType ];
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foreach ( $candidates as $candidate ) {
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if ( $candidate === CACHE_ACCEL ) {
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// CACHE_ACCEL might default to nothing if no APCu
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// See includes/ServiceWiring.php
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$class = self::getLocalServerCacheClass();
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if ( $class !== EmptyBagOStuff::class ) {
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return $candidate;
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}
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} elseif ( $candidate !== CACHE_NONE && $candidate !== CACHE_ANYTHING ) {
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return $candidate;
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}
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}
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$services = MediaWikiServices::getInstance();
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if ( $services->isServiceDisabled( 'DBLoadBalancer' ) ) {
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// The DBLoadBalancer service is disabled, so we can't use the database!
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$candidate = CACHE_NONE;
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} elseif ( $services->isStorageDisabled() ) {
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// Storage services are disabled because MediaWikiServices::disableStorage()
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// was called. This is typically the case during installation.
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$candidate = CACHE_NONE;
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} else {
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$candidate = CACHE_DB;
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}
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return $candidate;
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}
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/**
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* Factory function for CACHE_ACCEL (referenced from configuration)
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*
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* This will look for any APC or APCu style server-local cache.
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* A fallback cache can be specified if none is found.
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*
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* // Direct calls
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* ObjectCache::getLocalServerInstance( $fallbackType );
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*
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* // From $wgObjectCaches via newFromParams()
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* ObjectCache::getLocalServerInstance( [ 'fallback' => $fallbackType ] );
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*
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* @param int|string|array $fallback Fallback cache or parameter map with 'fallback'
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* @return BagOStuff
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* @throws InvalidArgumentException
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* @since 1.27
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*/
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public static function getLocalServerInstance( $fallback = CACHE_NONE ) {
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$cache = MediaWikiServices::getInstance()->getLocalServerObjectCache();
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if ( $cache instanceof EmptyBagOStuff ) {
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if ( is_array( $fallback ) ) {
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$fallback = $fallback['fallback'] ?? CACHE_NONE;
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}
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$cache = self::getInstance( $fallback );
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}
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return $cache;
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}
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/**
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* Get the main cluster-local cache object.
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*
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* @since 1.27
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* @return BagOStuff
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*/
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public static function getLocalClusterInstance() {
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return MediaWikiServices::getInstance()->get( '_LocalClusterCache' );
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}
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/**
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* Determine whether a config ID would access the database
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*
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* @param string|int $id A key in $wgObjectCaches
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* @return bool
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*/
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public static function isDatabaseId( $id ) {
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global $wgObjectCaches;
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if ( !isset( $wgObjectCaches[$id] ) ) {
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return false;
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}
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$cache = $wgObjectCaches[$id];
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if ( ( $cache['class'] ?? '' ) === SqlBagOStuff::class ) {
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return true;
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}
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// Ideally we would inspect the config, but it's complicated. The ID is suggestive.
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if ( $id === 'db-replicated' ) {
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return true;
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}
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if ( ( $cache['factory'] ?? '' ) === 'ObjectCache::newAnything' ) {
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$id = self::getAnythingId();
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return self::isDatabaseId( $id );
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}
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return false;
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}
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/**
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* Clear all the cached instances.
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*/
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public static function clear() {
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self::$instances = [];
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}
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/**
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* Create a new BagOStuff instance for local-server caching.
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*
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* Only use this if you explicitly require the creation of
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* a fresh instance. Whenever possible, use or inject the object
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* from MediaWikiServices::getLocalServerObjectCache() instead.
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*
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* NOTE: This method is called very early via Setup.php by ExtensionRegistry,
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* and thus must remain fairly standalone so as to not cause initialization
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* of the MediaWikiServices singleton.
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*
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* @since 1.35
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* @return BagOStuff
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*/
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public static function makeLocalServerCache(): BagOStuff {
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$params = [
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'reportDupes' => false,
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// Even simple caches must use a keyspace (T247562)
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'keyspace' => self::getDefaultKeyspace(),
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];
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$class = self::getLocalServerCacheClass();
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return new $class( $params );
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}
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/**
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* Get the class which will be used for the local server cache
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* @return string
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*/
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private static function getLocalServerCacheClass() {
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if ( self::$localServerCacheClass !== null ) {
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return self::$localServerCacheClass;
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}
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if ( function_exists( 'apcu_fetch' ) ) {
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// Make sure the APCu methods actually store anything
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if ( PHP_SAPI !== 'cli' || ini_get( 'apc.enable_cli' ) ) {
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return APCUBagOStuff::class;
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}
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} elseif ( function_exists( 'wincache_ucache_get' ) ) {
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return WinCacheBagOStuff::class;
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}
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return EmptyBagOStuff::class;
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}
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}
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