--- /dev/null
+<?php
+/**
+ * Functions to get cache objects.
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 2 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License along
+ * with this program; if not, write to the Free Software Foundation, Inc.,
+ * 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
+ * http://www.gnu.org/copyleft/gpl.html
+ *
+ * @file
+ * @ingroup Cache
+ */
+
+use MediaWiki\Logger\LoggerFactory;
+use MediaWiki\MediaWikiServices;
+
+/**
+ * Functions to get cache objects
+ *
+ * The word "cache" has two main dictionary meanings, and both
+ * are used in this factory class. They are:
+ *
+ * - a) Cache (the computer science definition).
+ * A place to store copies or computations on existing data for
+ * higher access speeds.
+ * - b) Storage.
+ * A place to store lightweight data that is not canonically
+ * stored anywhere else (e.g. a "hoard" of objects).
+ *
+ * The former should always use strongly consistent stores, so callers don't
+ * have to deal with stale reads. The latter may be eventually consistent, but
+ * callers can use BagOStuff:READ_LATEST to see the latest available data.
+ *
+ * Primary entry points:
+ *
+ * - ObjectCache::getMainWANInstance()
+ * Purpose: Memory cache.
+ * Stored in the local data-center's main cache (keyspace different from local-cluster cache).
+ * Delete events are broadcasted to other DCs main cache. See WANObjectCache for details.
+ *
+ * - ObjectCache::getLocalServerInstance( $fallbackType )
+ * Purpose: Memory cache for very hot keys.
+ * Stored only on the individual web server (typically APC or APCu for web requests,
+ * and EmptyBagOStuff in CLI mode).
+ * Not replicated to the other servers.
+ *
+ * - ObjectCache::getLocalClusterInstance()
+ * Purpose: Memory storage for per-cluster coordination and tracking.
+ * A typical use case would be a rate limit counter or cache regeneration mutex.
+ * Stored centrally within the local data-center. Not replicated to other DCs.
+ * Configured by $wgMainCacheType.
+ *
+ * - ObjectCache::getMainStashInstance()
+ * Purpose: Ephemeral global storage.
+ * Stored centrally within the primary data-center.
+ * Changes are applied there first and replicated to other DCs (best-effort).
+ * To retrieve the latest value (e.g. not from a replica DB), use BagOStuff::READ_LATEST.
+ * This store may be subject to LRU style evictions.
+ *
+ * - ObjectCache::getInstance( $cacheType )
+ * Purpose: Special cases (like tiered memory/disk caches).
+ * Get a specific cache type by key in $wgObjectCaches.
+ *
+ * All the above cache instances (BagOStuff and WANObjectCache) have their makeKey()
+ * method scoped to the *current* wiki ID. Use makeGlobalKey() to avoid this scoping
+ * when using keys that need to be shared amongst wikis.
+ *
+ * @ingroup Cache
+ */
+class ObjectCache {
+ /** @var BagOStuff[] Map of (id => BagOStuff) */
+ public static $instances = [];
+ /** @var WANObjectCache[] Map of (id => WANObjectCache) */
+ public static $wanInstances = [];
+
+ /**
+ * Get a cached instance of the specified type of cache object.
+ *
+ * @param string $id A key in $wgObjectCaches.
+ * @return BagOStuff
+ */
+ public static function getInstance( $id ) {
+ if ( !isset( self::$instances[$id] ) ) {
+ self::$instances[$id] = self::newFromId( $id );
+ }
+
+ return self::$instances[$id];
+ }
+
+ /**
+ * Get a cached instance of the specified type of WAN cache object.
+ *
+ * @since 1.26
+ * @param string $id A key in $wgWANObjectCaches.
+ * @return WANObjectCache
+ */
+ public static function getWANInstance( $id ) {
+ if ( !isset( self::$wanInstances[$id] ) ) {
+ self::$wanInstances[$id] = self::newWANCacheFromId( $id );
+ }
+
+ return self::$wanInstances[$id];
+ }
+
+ /**
+ * Create a new cache object of the specified type.
+ *
+ * @param string $id A key in $wgObjectCaches.
+ * @return BagOStuff
+ * @throws InvalidArgumentException
+ */
+ public static function newFromId( $id ) {
+ global $wgObjectCaches;
+
+ if ( !isset( $wgObjectCaches[$id] ) ) {
+ // Always recognize these ones
+ if ( $id === CACHE_NONE ) {
+ return new EmptyBagOStuff();
+ } elseif ( $id === 'hash' ) {
+ return new HashBagOStuff();
+ }
+
+ throw new InvalidArgumentException( "Invalid object cache type \"$id\" requested. " .
+ "It is not present in \$wgObjectCaches." );
+ }
+
+ return self::newFromParams( $wgObjectCaches[$id] );
+ }
+
+ /**
+ * Get the default keyspace for this wiki.
+ *
+ * This is either the value of the `CachePrefix` configuration variable,
+ * or (if the former is unset) the `DBname` configuration variable, with
+ * `DBprefix` (if defined).
+ *
+ * @return string
+ */
+ public static function getDefaultKeyspace() {
+ global $wgCachePrefix;
+
+ $keyspace = $wgCachePrefix;
+ if ( is_string( $keyspace ) && $keyspace !== '' ) {
+ return $keyspace;
+ }
+
+ return wfWikiID();
+ }
+
+ /**
+ * Create a new cache object from parameters.
+ *
+ * @param array $params Must have 'factory' or 'class' property.
+ * - factory: Callback passed $params that returns BagOStuff.
+ * - class: BagOStuff subclass constructed with $params.
+ * - loggroup: Alias to set 'logger' key with LoggerFactory group.
+ * - .. Other parameters passed to factory or class.
+ * @return BagOStuff
+ * @throws InvalidArgumentException
+ */
+ public static function newFromParams( $params ) {
+ if ( isset( $params['loggroup'] ) ) {
+ $params['logger'] = LoggerFactory::getInstance( $params['loggroup'] );
+ } else {
+ $params['logger'] = LoggerFactory::getInstance( 'objectcache' );
+ }
+ if ( !isset( $params['keyspace'] ) ) {
+ $params['keyspace'] = self::getDefaultKeyspace();
+ }
+ if ( isset( $params['factory'] ) ) {
+ return call_user_func( $params['factory'], $params );
+ } elseif ( isset( $params['class'] ) ) {
+ $class = $params['class'];
+ // Automatically set the 'async' update handler
+ $params['asyncHandler'] = isset( $params['asyncHandler'] )
+ ? $params['asyncHandler']
+ : 'DeferredUpdates::addCallableUpdate';
+ // Enable reportDupes by default
+ $params['reportDupes'] = isset( $params['reportDupes'] )
+ ? $params['reportDupes']
+ : true;
+ // Do b/c logic for SqlBagOStuff
+ if ( is_a( $class, SqlBagOStuff::class, true ) ) {
+ if ( isset( $params['server'] ) && !isset( $params['servers'] ) ) {
+ $params['servers'] = [ $params['server'] ];
+ unset( $params['server'] );
+ }
+ // In the past it was not required to set 'dbDirectory' in $wgObjectCaches
+ if ( isset( $params['servers'] ) ) {
+ foreach ( $params['servers'] as &$server ) {
+ if ( $server['type'] === 'sqlite' && !isset( $server['dbDirectory'] ) ) {
+ $server['dbDirectory'] = MediaWikiServices::getInstance()
+ ->getMainConfig()->get( 'SQLiteDataDir' );
+ }
+ }
+ }
+ }
+
+ // Do b/c logic for MemcachedBagOStuff
+ if ( is_subclass_of( $class, MemcachedBagOStuff::class ) ) {
+ if ( !isset( $params['servers'] ) ) {
+ $params['servers'] = $GLOBALS['wgMemCachedServers'];
+ }
+ if ( !isset( $params['debug'] ) ) {
+ $params['debug'] = $GLOBALS['wgMemCachedDebug'];
+ }
+ if ( !isset( $params['persistent'] ) ) {
+ $params['persistent'] = $GLOBALS['wgMemCachedPersistent'];
+ }
+ if ( !isset( $params['timeout'] ) ) {
+ $params['timeout'] = $GLOBALS['wgMemCachedTimeout'];
+ }
+ }
+ return new $class( $params );
+ } else {
+ throw new InvalidArgumentException( "The definition of cache type \""
+ . print_r( $params, true ) . "\" lacks both "
+ . "factory and class parameters." );
+ }
+ }
+
+ /**
+ * Factory function for CACHE_ANYTHING (referenced from DefaultSettings.php)
+ *
+ * CACHE_ANYTHING means that stuff has to be cached, not caching is not an option.
+ * If a caching method is configured for any of the main caches ($wgMainCacheType,
+ * $wgMessageCacheType, $wgParserCacheType), then CACHE_ANYTHING will effectively
+ * be an alias to the configured cache choice for that.
+ * If no cache choice is configured (by default $wgMainCacheType is CACHE_NONE),
+ * then CACHE_ANYTHING will forward to CACHE_DB.
+ *
+ * @param array $params
+ * @return BagOStuff
+ */
+ public static function newAnything( $params ) {
+ global $wgMainCacheType, $wgMessageCacheType, $wgParserCacheType;
+ $candidates = [ $wgMainCacheType, $wgMessageCacheType, $wgParserCacheType ];
+ foreach ( $candidates as $candidate ) {
+ $cache = false;
+ if ( $candidate !== CACHE_NONE && $candidate !== CACHE_ANYTHING ) {
+ $cache = self::getInstance( $candidate );
+ // CACHE_ACCEL might default to nothing if no APCu
+ // See includes/ServiceWiring.php
+ if ( !( $cache instanceof EmptyBagOStuff ) ) {
+ return $cache;
+ }
+ }
+ }
+
+ if ( MediaWikiServices::getInstance()->isServiceDisabled( 'DBLoadBalancer' ) ) {
+ // The LoadBalancer is disabled, probably because
+ // MediaWikiServices::disableStorageBackend was called.
+ $candidate = CACHE_NONE;
+ } else {
+ $candidate = CACHE_DB;
+ }
+
+ return self::getInstance( $candidate );
+ }
+
+ /**
+ * Factory function for CACHE_ACCEL (referenced from DefaultSettings.php)
+ *
+ * This will look for any APC or APCu style server-local cache.
+ * A fallback cache can be specified if none is found.
+ *
+ * // Direct calls
+ * ObjectCache::getLocalServerInstance( $fallbackType );
+ *
+ * // From $wgObjectCaches via newFromParams()
+ * ObjectCache::getLocalServerInstance( [ 'fallback' => $fallbackType ] );
+ *
+ * @param int|string|array $fallback Fallback cache or parameter map with 'fallback'
+ * @return BagOStuff
+ * @throws InvalidArgumentException
+ * @since 1.27
+ */
+ public static function getLocalServerInstance( $fallback = CACHE_NONE ) {
+ $cache = MediaWikiServices::getInstance()->getLocalServerObjectCache();
+ if ( $cache instanceof EmptyBagOStuff ) {
+ if ( is_array( $fallback ) ) {
+ $fallback = isset( $fallback['fallback'] ) ? $fallback['fallback'] : CACHE_NONE;
+ }
+ $cache = self::getInstance( $fallback );
+ }
+
+ return $cache;
+ }
+
+ /**
+ * Create a new cache object of the specified type.
+ *
+ * @since 1.26
+ * @param string $id A key in $wgWANObjectCaches.
+ * @return WANObjectCache
+ * @throws UnexpectedValueException
+ */
+ public static function newWANCacheFromId( $id ) {
+ global $wgWANObjectCaches, $wgObjectCaches;
+
+ if ( !isset( $wgWANObjectCaches[$id] ) ) {
+ throw new UnexpectedValueException(
+ "Cache type \"$id\" requested is not present in \$wgWANObjectCaches." );
+ }
+
+ $params = $wgWANObjectCaches[$id];
+ if ( !isset( $wgObjectCaches[$params['cacheId']] ) ) {
+ throw new UnexpectedValueException(
+ "Cache type \"{$params['cacheId']}\" is not present in \$wgObjectCaches." );
+ }
+ $params['store'] = $wgObjectCaches[$params['cacheId']];
+
+ return self::newWANCacheFromParams( $params );
+ }
+
+ /**
+ * Create a new cache object of the specified type.
+ *
+ * @since 1.28
+ * @param array $params
+ * @return WANObjectCache
+ * @throws UnexpectedValueException
+ */
+ public static function newWANCacheFromParams( array $params ) {
+ $erGroup = MediaWikiServices::getInstance()->getEventRelayerGroup();
+ foreach ( $params['channels'] as $action => $channel ) {
+ $params['relayers'][$action] = $erGroup->getRelayer( $channel );
+ $params['channels'][$action] = $channel;
+ }
+ $params['cache'] = self::newFromParams( $params['store'] );
+ if ( isset( $params['loggroup'] ) ) {
+ $params['logger'] = LoggerFactory::getInstance( $params['loggroup'] );
+ } else {
+ $params['logger'] = LoggerFactory::getInstance( 'objectcache' );
+ }
+ $class = $params['class'];
+
+ return new $class( $params );
+ }
+
+ /**
+ * Get the main cluster-local cache object.
+ *
+ * @since 1.27
+ * @return BagOStuff
+ */
+ public static function getLocalClusterInstance() {
+ global $wgMainCacheType;
+
+ return self::getInstance( $wgMainCacheType );
+ }
+
+ /**
+ * Get the main WAN cache object.
+ *
+ * @since 1.26
+ * @return WANObjectCache
+ * @deprecated Since 1.28 Use MediaWikiServices::getMainWANObjectCache()
+ */
+ public static function getMainWANInstance() {
+ return MediaWikiServices::getInstance()->getMainWANObjectCache();
+ }
+
+ /**
+ * Get the cache object for the main stash.
+ *
+ * Stash objects are BagOStuff instances suitable for storing light
+ * weight data that is not canonically stored elsewhere (such as RDBMS).
+ * Stashes should be configured to propagate changes to all data-centers.
+ *
+ * Callers should be prepared for:
+ * - a) Writes to be slower in non-"primary" (e.g. HTTP GET/HEAD only) DCs
+ * - b) Reads to be eventually consistent, e.g. for get()/getMulti()
+ * In general, this means avoiding updates on idempotent HTTP requests and
+ * avoiding an assumption of perfect serializability (or accepting anomalies).
+ * Reads may be eventually consistent or data might rollback as nodes flap.
+ * Callers can use BagOStuff:READ_LATEST to see the latest available data.
+ *
+ * @return BagOStuff
+ * @since 1.26
+ * @deprecated Since 1.28 Use MediaWikiServices::getMainObjectStash
+ */
+ public static function getMainStashInstance() {
+ return MediaWikiServices::getInstance()->getMainObjectStash();
+ }
+
+ /**
+ * Clear all the cached instances.
+ */
+ public static function clear() {
+ self::$instances = [];
+ self::$wanInstances = [];
+ }
+}
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