X-Git-Url: https://scripts.mit.edu/gitweb/autoinstallsdev/mediawiki.git/blobdiff_plain/19e297c21b10b1b8a3acad5e73fc71dcb35db44a..6932310fd58ebef145fa01eb76edf7150284d8ea:/includes/objectcache/ObjectCache.php

diff --git a/includes/objectcache/ObjectCache.php b/includes/objectcache/ObjectCache.php
new file mode 100644
index 00000000..3370e5b9
--- /dev/null
+++ b/includes/objectcache/ObjectCache.php
@@ -0,0 +1,404 @@
+<?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 = [];
+	}
+}