Advanced Cache Policies module

Operations Bundled: DX Core

Edition	DX Core
License	MLA
Issues	MGNLADVCACHE
Maven site	Advanced Cache
Latest	2.3.4

Edition

DX Core

License

MLA

Issues

MGNLADVCACHE

Maven site

Advanced Cache

Latest

2.3.4

The Advanced Cache module is collection of advanced cache strategies to help minimize load on the server while ensuring fresh content is served to the users.

Installing with Maven

Bundled modules are automatically installed for you.

If the module is unbundled, add the following to your bundle including your project’s <dependencyManagement> section and your webapp’s <dependencies> section. If the module is unbundled but the version is managed by the parent POM, add the following to your webapp’s <dependencies> section.

<dependency>
  <groupId>info.magnolia.advancedcache</groupId>
  <artifactId>magnolia-advanced-cache</artifactId>
  <version>2.3.4</version> (1)
</dependency>

1	Should you need to specify the module version, do it using `<version>`.

Uninstalling

Set the cache policy in /modules/cache/config/contentCaching/defaultPageCache/cachePolicy@class back to the default value info.magnolia.module.cache.cachepolicy.Default.
Remove the /modules/advanced-cache node and its subnodes.
Shut down Magnolia, remove the Advanced Cache module JAR (magnolia-advanced-cache.jar) from WEB-INF/lib and start up Magnolia again.

Caching strategies

Serving old content while re-caching

Using this strategy, cache is not completely cleaned on content update and entries are retained. After update, when the first request comes in, fresh cache entry generation is triggered and all further requests for the same entry are served from old cache content until the new entry is ready.

Set /modules/cache/config/contentCaching/defaultPageCache/cachePolicy@class to info.magnolia.module.advancedcache.ServeUntilRecachedCachePolicy.
Set /modules/cache/config/contentCaching/defaultPageCache/flushPolicy/policies/flushAll@class to info.magnolia.module.advancedcache.NotifyFlushListeningPolicy.

Eager re-caching

Using this strategy, cache keeps a list of the most frequently served entries. The system attempts to refresh these entries as soon as it detects a content update. All other entries are re-cached on request. It is possible to configure the number of entries to re-cache immediately and to set the lifetime of the most served content.

To enable eager re-caching:

Set /modules/cache/config/contentCaching/defaultPageCache/cachePolicy@class to info.magnolia.module.advancedcache.EagerRecacheCachePolicy.
Set /modules/cache/config/contentCaching/defaultPageCache/flushPolicy/flushAll@class to info.magnolia.module.advancedcache.EagerRecacheFlushPolicy.
Set /modules/cache/config/contentCaching/defaultPageCache/executors/store/cacheContent@class to info.magnolia.module.cache.executor.Store.

Changing default flush policy

By default, statistics about served pages are retained indefinitely. If you want to force the system to flush the cache after each content update:

Create a resetAfterUpdate property node under flushPolicy.
Set the value to true.

By default, the top 100 entries are eagerly re-cached on every update. To change that number:

Create an eagerRecache property node under flushPolicy.
Set the value to the number of top entries in the list you wish to have eagerly re-cached.

Changing default waiting time

By default, Magnolia waits for 10 seconds before attempting to re-cache content. This timeout is controlled by the blockingTimeout property configured in the Ehcache 3 back-end. The blockingTimeout property applies to the whole cache factory.

If you want to change the waiting time for a particular cache policy, add a timeout property with the number of milliseconds to wait (the default value is 10000).

Changes to cache policies and executors are applied immediately. Setting incorrect values can render the Magnolia instance inaccessible.

If this happens, try the Groovy Rescue App:

DX Core Groovy module
PaaS Rescue App

Timestamp for last flushing

The advanced flush policies update a lastUpdateTimestamp property to record the last flushing event. The timestamp allows the corresponding cache policy to identify which cache entries need to be regenerated. When you delegate cache to an advanced cache policy, create a property at a path that includes the name of your custom policy.

Example 1: Serving old content while re-caching

/modules/advanced-cache/config/notifyFlushListeningPolicy@lastUpdateTimeStamp (default)
/modules/advanced-cache/config/notifyFlushListeningPolicy/<custom_cache_name>@lastUpdateTimeStamp (custom)

Example 2: Eager re-caching

/modules/advanced-cache/config/eagerRecacheFlushPolicy@lastUpdateTimeStamp (default)
/modules/advanced-cache/config/eagerRecacheFlushPolicy/<custom_cache_name>@lastUpdateTimeStamp (custom)

where <custom_cache_name> is the name of your custom policy.

Headless personalization and caching

For headless personalization to work correctly with content caching in Magnolia, you have to set /modules/cache/config/contentCaching/<your-configuration>/cachePolicy@includePersonalizedDescendants to true.

By configuring this property, the dynamic page-caching function is disabled.

Magnolia does not currently support caching for different headers or cookies. Therefore, it is impossible to specify for which headers or cookies a response should be cached.

See MGNLCACHE-245 for the upcoming improvement.

Multisite cache configuration

When content is published, the cache on the public instance is flushed to show the new content. This increases the load on the server and affects all sites in a multisite environment. You can configure multiple cache configurations to ensure that only cache entries that belong to the same subree (site) as the published content are flushed. Use Advanced Cache app module for easy configuration or just do it manually:

Set /modules/advanced-cache/config@createSeparateCachesForEachSite=true. This creates caches for each site defined. It uses the defaultPageCache configuration for each site if /modules/cache/config/contentCaching/SITE-NAME doesn’t exist.
Set `/server/filters/cache@class=info.magnolia.module.advancedcache.filter.SiteAwareCacheFilter.`This filter chooses the right site-specific cache to use so you don’t need to have separate cache filters per cache.
Create /modules/cache/config/contentCaching/defaultPageCache/flushPolicy/policies/flushSiteAware@class=info.magnolia.module.advancedcache.SiteAwareFlushAllListeningPolicy.
For all site-aware workspaces (those which have separate subtrees for each site):
1. Exclude the workspace from the default flush policy: /modules/cache/config/contentCaching/defaultPageCache/flushPolicy/policies/flushAll/excludedWorkspaces@WORKSPACE_NAME=WORKSPACE_NAME.
2. Register this workspace to site aware flush policy: /modules/cache/config/contentCaching/defaultPageCache/flushPolicy/policies/flushSiteAware/workspaces@WORKSPACE_NAME=WORKSPACE_NAME.
Restart your instance.

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