Cache bundle is a OSGi bundle that provides caching mechanisms for pages or components. Cache bundle uses for it cache filter.
Add following dependency to your project:
<dependency>
<groupId>com.cognifide.cq</groupId>
<artifactId>sling-caching-filter</artifactId>
<version>0.9.0-SNAPSHOT</version>
</dependency>
or download the sources and use the maven-sling-plugin:
mvn clean package sling:install
Cache filter is able to cache all pages/renderers/components. It is configured to filter all sling requests on the component level. The only limit is that the whole component is being cached - to cache only a part of a component please use the cache tag.
It is strongly discouraged to enable cache filter on the author instance since this produces issues with CQ js code.
Cache filter can be configured in two places: in the OSGi console (filter configuration and components configurations). Under the hood jcache with ehcache are used.
OSGi console allows to modify the following properties:
- Enabled - enables/disables cache filter
- Validity itme - Maximum default time (in seconds) after which cache entry must be refreshed
- Path aliases - define aliases for paths, syntax
$<alias name>|<path 1>|<path 2>|..., where$is a mandatory character before alias name, and|is a separator between paths - Max entries in cache - defines max entries in cache, disc and heap.
0means unlimited. - Eviction policy - sets eviction policy, possible values:
LRU, LFU, FIFO.
OSGi console allows to add configuration per component/resource type.
| attribute name | attribute type | required | description | default value |
|---|---|---|---|---|
| Activate (cache.config.active) | boolean | no | enables/disables caching of given component | false |
| Resource type (cache.config.resource.type) | String | yes | component resource type | -1 |
| Validity time (cache.config.validity.time) | integer | no | specifies cache entry validity time (in seconds) | duration property read from the OSGi console |
| Cache level (cache.config.cache.level) | String | no | specifies the level of component caching | -1 |
| Invalidate on self (cache.config.invalidate.on.self) | boolean | no | when set to true cached instance will be refreshed if it has been changed | true |
| Invalidate on containing page (cache.config.invalidate.on.containing.page) | boolean | no | when set to true cached instance will be refreshed when something will change on page containing cached instance | false |
| Invalidate on referenced fields (cache.config.invalidate.on.referenced.fields) | String[] | no | List of component fields that store links to content/configuration/etc. pages. Links from those fields are loaded and each content change inside nodes pointed to by those links will invalidate cache of the current component | empty list |
| Invalidate on paths (cache.config.invalidate.on.paths) | String[] | no | List of paths (regular expressions). If a path of any changed JCR node matches any path from the list then the cache of the current component is invalidated | empty list |
Allowed values for the Cache level:
- -1 - Each instance is cached separately (resource path is used to create cache key).
- 0 - There is only one instance of the component on the whole site. To determine which instance is cached, the first-renderer rule applies (the first rednered component is cached and used on other pages)
- any positive value - Component is cached per path. The value of cache level determines how many parts of the request URI (separated by the "/" character) will be used to generate cache key. For example, when this value is set to 3 and the path is /content/acme/en_gb/home.html, then only "/content/acme/en_gb" will be used to generate the key meaning that component will be cached per language.
Things/ideas left out for the future:
- implement (if ever required) different caching strategies for different selectors
- add configuration of paths that are (or are not) filtered by the cache filter