Configuring CachingContentStore

To demonstrate step-by-step configuration of the CachingContentStore class, the spring context file, caching-content-store-context.xml.sample is used as a starting point for adding caching to a content store. Once configured, you can activate the sample file by removing the .sample file extension and placing it in your SkyVault installation extension directory at <ALFRESCO_HOME>/tomcat/shared/classes/alfresco/extension.

Define an instance of the CachingContentStore class. This is the top level bean that ties together the CCS as a whole.
```
<bean id="fileContentStore" class="org.alfresco.repo.content.caching.CachingContentStore" init-method="init">
  <property name="backingStore" ref="backingStore"/>
  <property name="cache" ref="contentCache"/>
  <property name="cacheOnInbound" value="${system.content.caching.cacheOnInbound}"/>
  <property name="quota" ref="standardQuotaManager"/>
</bean> 
```
In this case, the fileContentStore bean is overridden. The ContentService bean uses fileContentStore bean, so CCS is used automatically. You can also specify a different name and an overridden contentService bean. The main collaborators of backingStore, cache and quota refer to the beans for Backing Store, Content Cache and Quota Manager as shown in the diagram in the CachingContentStore overview topic. Each CachingContentStore class should have its own dedicated instances of these collaborators and they should not be shared across other CachingContentStore beans, should you have any defined.

Define a backing store. This CCS uses this ContentStore to provide caching for TenantRoutingS3ContentStore.

<bean id="tenantRoutingContentStore" 
         class="org.alfresco.module.org_alfresco_module_cloud.repo.content.s3store.TenantRoutingS3ContentStore" 
         parent="baseTenantRoutingContentStore">
       
  <property name="defaultRootDir" value="${dir.contentstore}" />
  <property name="s3AccessKey" value="${s3.accessKey}" />
  <property name="s3SecretKey" value="${s3.secretKey}" />
  <property name="s3BucketName" value="${s3.bucketName}" />
  <property name="s3BucketLocation" value="${s3.bucketLocation}" />
  <property name="s3FlatRoot" value="${s3.flatRoot}" />
  <property name="globalProperties">
    <ref bean="global-properties" />
  </property>
   
</bean>

Note: Remember to change this bean's ID to backingStore for use with the preceding XML snippet, or change the ref attribute in the fileContentStore bean definition to refer to the correct ID (tenantRoutingContentStore).

Define a ContentCache. This object is responsible for placing content into (and retrieving content from) the cache.

<bean id="contentCache" class="org.alfresco.repo.content.caching.ContentCacheImpl">
  <property name="memoryStore" ref="cachingContentStoreCache"/>
  <property name="cacheRoot" value="${dir.cachedcontent}"/>
</bean>

The ContentCacheImpl uses a fast lookup table provided by Ehcache for determining whether an item is currently cached by the CCS, for controlling the maximum number of items in the cache and their Time To Live (TTL). The lookup table is specified here by the memoryStore property. The ContentCacheImpl also uses a directory on the local filesystem for storing binary content data (the actual content being cached). This directory is specified by the cacheRoot property. The following code illustrates the bean referencing the memoryStore reference above:

<bean id="cachingContentStoreCache" class="org.alfresco.repo.cache.EhCacheAdapter">
       <property name="cache">
           <bean class="org.springframework.cache.ehcache.EhCacheFactoryBean">
               <property name="cacheManager">
                   <ref bean="internalEHCacheManager" />
               </property>
               <property name="cacheName">
                   <value>org.alfresco.cache.cachingContentStoreCache</value>
               </property>
               <property name="eternal" value="false"/>
               <property name="timeToLive" value="${system.content.caching.timeToLiveSeconds}"/>
               <property name="timeToIdle" value="${system.content.caching.timeToIdleSeconds}"/>
               <property name="maxElementsInMemory" value="${system.content.caching.maxElementsInMemory}"/>
               <property name="maxElementsOnDisk" value="${system.content.caching.maxElementsOnDisk}"/>
               <property name="overflowToDisk" value="true"/>
               <property name="diskPersistent" value="true"/>
           </bean>
       </property>
   </bean>

Now that you have configured the key components of the CachingContentStore class, backing store (ContentStore) and ContentCache, you can optionally specify a quota manager. If you do not wish to specify the quota manager, then the UnlimitedQuotaStrategy will be used. The example CCS bean above expects this bean to be defined:

<bean id="standardQuotaManager"
       class="org.alfresco.repo.content.caching.quota.StandardQuotaStrategy"
       init-method="init"
       destroy-method="shutdown">
     <property name="maxUsageMB" value="4096"/>
     <property name="maxFileSizeMB" value="0"/>
     <property name="cache" ref="contentCache"/>
     <property name="cleaner" ref="cachedContentCleaner"/>
</bean>

Finally, to ensure that the disk space is used in a controlled manner, a CachedContentCleaner should be configured to clean up cached content files that are no longer being used by the cache.

bean id="cachingContentStoreCleanerJobDetail" class="org.springframework.scheduling.quartz.JobDetailBean">
       <property name="jobClass">
           <value>org.alfresco.repo.content.caching.cleanup.CachedContentCleanupJob</value>
       </property>
       <property name="jobDataAsMap">
           <map>
               <entry key="cachedContentCleaner">
                   <ref bean="cachedContentCleaner" />
               </entry>
           </map>
       </property>
   </bean>
   
   <bean id="cachedContentCleaner"
       class="org.alfresco.repo.content.caching.cleanup.CachedContentCleaner"
       init-method="init">
       <property name="minFileAgeMillis" value="${system.content.caching.minFileAgeMillis}"/>
       <property name="maxDeleteWatchCount" value="${system.content.caching.maxDeleteWatchCount}"/>
       <property name="cache" ref="contentCache"/>
       <property name="usageTracker" ref="standardQuotaManager"/>
   </bean>
   
   <bean id="cachingContentStoreCleanerTrigger" class="org.alfresco.util.CronTriggerBean">
       <property name="jobDetail">
           <ref bean="cachingContentStoreCleanerJobDetail" />
       </property>
       <property name="scheduler">
           <ref bean="schedulerFactory" />
       </property>
       <property name="cronExpression">
           <value>${system.content.caching.contentCleanup.cronExpression}</value>
       </property>
   </bean>

Note that both the cleaner and the quota manager limit the usage of disk space but hey do not perform the same function. In addition to removing the orphaned content, the cleaner's job is to remove files that are out of use from the cache due to parameters, such as TTL, which sets the maximum time an item should be used by the CCS. The quota manager exists to set specific requirements in terms of allowed disk space.

A number of property placeholders are used in the above definitions. You can replace them directly in your configuration with the required values, or you can use the placeholders as they are and set the values in the repository.properties file. An advantage of using the property placeholders is that the sample file can be used with very few changes and the appropriate properties can be modified to get the CCS running with little effort.

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