Author: bstansberry(a)jboss.com Date: 2007-08-27 13:11:11 -0400 (Mon, 27 Aug 2007) New Revision: 4442 Modified: core/trunk/src/main/docbook/userguide/en/modules/cache_loaders.xml Log: Add more passivation docs Modified: core/trunk/src/main/docbook/userguide/en/modules/cache_loaders.xml =================================================================== --- core/trunk/src/main/docbook/userguide/en/modules/cache_loaders.xml 2007-08-26 03:18:52 UTC (rev 4441) +++ core/trunk/src/main/docbook/userguide/en/modules/cache_loaders.xml 2007-08-27 17:11:11 UTC (rev 4442) @@ -1,4 +1,7 @@ -<chapter id="cache_loaders"> + + + <orderedlist> + <listitem><chapter id="cache_loaders"> <title>Cache Loaders</title> <para>JBoss Cache can use a <literal>CacheLoader</literal> @@ -1064,6 +1067,64 @@ When passivation is used, only the first cache loader configured is used and all others are ignored. </para> + + <section> + <title>Cache Loader Behavior with Passivation Disabled vs. Enabled</title> + + <para> + When passivation is disabled, whenever an element is modified, added or + removed, then that modification is persisted in the backend store via + the cache loader. There is no direct relationship between eviction and + cache loading. If you don't use eviction, what's in the persistent store + is basically a copy of what's in memory. If you do use eviction, what's + in the persistent store is basically a superset of what's in memory + (i.e. it includes nodes that have been evicted from memory). + </para> + + <para> + When passivation is enabled, there is a direct relationship between + eviction and the cache loader. Writes to the persistent store via the + cache loader only occur as part of the eviction process. Data is deleted + from the persistent store when the application reads it back into + memory. In this case, what's in memory and what's in the persistent + store are two subsets of the total information set, with no intersection between the subsets. + </para> + + <para> + Following is a simple example, showing what state is in RAM and in the + persistent store after each step of a 6 step process: + </para> + + <orderedlist> + <listitem>Insert /A</listitem> + <listitem>Insert /B</listitem> + <listitem>Eviction thread runs, evicts /A</listitem> + <listitem>Read /A</listitem> + <listitem>Eviction thread runs, evicts /B</listitem> + <listitem>Remove /B</listitem> + </orderedlist> + + <para> When passivation is disabled:</para> + <programlisting> +1) RAM: /A Disk: /A +2) RAM: /A, /B Disk: /A, /B +3) RAM: /B Disk: /A, /B +4) RAM: /A, /B Disk: /A, /B +5) RAM: /A Disk: /A, /B +6) RAM: /A Disk: /A + </programlisting> + + <para>When passivation is enabled:</para> + <programlisting> +1) RAM: /A Disk: +2) RAM: /A, /B Disk: +3) RAM: /B Disk: /A +4) RAM: /A, /B Disk: +5) RAM: /A Disk: /B +6) RAM: /A Disk: + </programlisting> + </section> + </section> <section>