Current File : //www/varak.net/wiki.varak.net/includes/objectcache/ObjectCache.php
<?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'] = $params['asyncHandler'] ?? 'DeferredUpdates::addCallableUpdate';
// Enable reportDupes by default
$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 = $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 ) {
global $wgCommandLineMode;
$services = MediaWikiServices::getInstance();
$erGroup = $services->getEventRelayerGroup();
if ( isset( $params['channels'] ) ) {
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 {
$params['logger'] = LoggerFactory::getInstance( 'objectcache' );
}
if ( !$wgCommandLineMode ) {
// Send the statsd data post-send on HTTP requests; avoid in CLI mode (T181385)
$params['stats'] = $services->getStatsdDataFactory();
// Let pre-emptive refreshes happen post-send on HTTP requests
$params['asyncHandler'] = [ DeferredUpdates::class, 'addCallableUpdate' ];
}
$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 = [];
}
/**
* Detects which local server cache library is present and returns a configuration for it
* @since 1.32
*
* @return int|string Index to cache in $wgObjectCaches
*/
public static function detectLocalServerCache() {
if ( function_exists( 'apc_fetch' ) ) {
return 'apc';
} elseif ( function_exists( 'apcu_fetch' ) ) {
return 'apcu';
} elseif ( function_exists( 'wincache_ucache_get' ) ) {
return 'wincache';
}
return CACHE_NONE;
}
}
Mini Shell