[jboss-jira] [JBoss JIRA] Updated: (JBCACHE-777) Creating a custom cache loader which delegates to a standard cache loader, can generate misleading WARN messages

[Galder Zamarreno (JIRA)]

     [ http://jira.jboss.com/jira/browse/JBCACHE-777?page=all ]

Galder Zamarreno updated JBCACHE-777:
-------------------------------------

        Summary: Creating a custom cache loader which delegates to a standard cache loader, can generate misleading WARN messages  (was: FileCacheLoader can return null for get(fqn) breaking the JavaDoc requirement for CacheLoader.get(fqn))
    Description: 
FileCacheLoader can return a null value for get(fqn) if the node does not exist.

 /**
    * Returns all keys and values from the persistent store, given a fully qualified name.
    *
    * NOTE that the expected return value of this method has changed from JBossCache 1.2.x
    * and before!  This will affect cache loaders written prior to JBossCache 1.3.0 and such
    * implementations should be checked for compliance with the behaviour expected.
    *
    * @param name
    * @return Map<Object,Object> keys and values for the given node. Returns
    * null if the node is not found.  If the node is found but has no
    * attributes, this method returns an empty Map.
    * @throws Exception
 */

If the customer creates a custom cache loader which delegates to a FileCacheLoader, the 
following misleading warning message is logged:

10:52:10.839 WARN [MessageListenerThread - Belvedere/Desk/CacheLoaderInterceptor] CacheLoader.get(Fqn) returned a null; assuming the node nodes not exist.
10:52:10.839 WARN [MessageListenerThread - Belvedere/Desk/CacheLoaderInterceptor] The CacheLoader interface has changed since JBossCache 1.3.x
10:52:10.839 WARN [MessageListenerThread - Belvedere/Desk/CacheLoaderInterceptor] Please see http://jira.jboss.com/jira/browse/JBCACHE-118
10:52:10.849 WARN [MessageListenerThread - Belvedere/Desk/CacheLoaderInterceptor] CacheLoader.get() should return an empty Map if the node does exist but doesn't have any attributes.

This occurrs even though the FileCacheLoader is actually doing the job accordingly.

  was:
FileCacheLoader can return a null value for get(fqn) which goes against the JavaDoc 
requirements for that method:

 /**
    * Returns all keys and values from the persistent store, given a fully qualified name.
    *
    * NOTE that the expected return value of this method has changed from JBossCache 1.2.x
    * and before!  This will affect cache loaders written prior to JBossCache 1.3.0 and such
    * implementations should be checked for compliance with the behaviour expected.
    *
    * @param name
    * @return Map<Object,Object> keys and values for the given node. Returns
    * null if the node is not found.  If the node is found but has no
    * attributes, this method returns an empty Map.
    * @throws Exception
 */

If a get(fqn) operation occurrs before a put and the node (directory) does not exist, FCL returns 
null when it should return an empty Map.

If the customer creates a custom cache loader which delegates to a FileCacheLoader, the 
following misleading warning message is logged:

10:52:10.839 WARN [MessageListenerThread - Belvedere/Desk/CacheLoaderInterceptor] CacheLoader.get(Fqn) returned a null; assuming the node nodes not exist.
10:52:10.839 WARN [MessageListenerThread - Belvedere/Desk/CacheLoaderInterceptor] The CacheLoader interface has changed since JBossCache 1.3.x
10:52:10.839 WARN [MessageListenerThread - Belvedere/Desk/CacheLoaderInterceptor] Please see http://jira.jboss.com/jira/browse/JBCACHE-118
10:52:10.849 WARN [MessageListenerThread - Belvedere/Desk/CacheLoaderInterceptor] CacheLoader.get() should return an empty Map if the node does exist but doesn't have any attributes.


Update the case comment and title due to misunderstanding of the javadoc.
FileCacheLoader fullfills the javadoc, but in the special occasion of having a custom
cache loader that delegates on a org.jboss.cache CacheLoader, this WARN messages
would be log thinking that the newly create custom cache loader is breaking the contract.

> Creating a custom cache loader which delegates to a standard cache loader, can generate misleading WARN messages
> ----------------------------------------------------------------------------------------------------------------
>
>                 Key: JBCACHE-777
>                 URL: http://jira.jboss.com/jira/browse/JBCACHE-777
>             Project: JBoss Cache
>          Issue Type: Bug
>      Security Level: Public(Everyone can see) 
>    Affects Versions: 1.3.0.SP3, 1.4.0.SP1
>            Reporter: Galder Zamarreno
>         Assigned To: Galder Zamarreno
>            Priority: Minor
>
> FileCacheLoader can return a null value for get(fqn) if the node does not exist.
>  /**
>     * Returns all keys and values from the persistent store, given a fully qualified name.
>     *
>     * NOTE that the expected return value of this method has changed from JBossCache 1.2.x
>     * and before!  This will affect cache loaders written prior to JBossCache 1.3.0 and such
>     * implementations should be checked for compliance with the behaviour expected.
>     *
>     * @param name
>     * @return Map<Object,Object> keys and values for the given node. Returns
>     * null if the node is not found.  If the node is found but has no
>     * attributes, this method returns an empty Map.
>     * @throws Exception
>  */
> If the customer creates a custom cache loader which delegates to a FileCacheLoader, the 
> following misleading warning message is logged:
> 10:52:10.839 WARN [MessageListenerThread - Belvedere/Desk/CacheLoaderInterceptor] CacheLoader.get(Fqn) returned a null; assuming the node nodes not exist.
> 10:52:10.839 WARN [MessageListenerThread - Belvedere/Desk/CacheLoaderInterceptor] The CacheLoader interface has changed since JBossCache 1.3.x
> 10:52:10.839 WARN [MessageListenerThread - Belvedere/Desk/CacheLoaderInterceptor] Please see http://jira.jboss.com/jira/browse/JBCACHE-118
> 10:52:10.849 WARN [MessageListenerThread - Belvedere/Desk/CacheLoaderInterceptor] CacheLoader.get() should return an empty Map if the node does exist but doesn't have any attributes.
> This occurrs even though the FileCacheLoader is actually doing the job accordingly.

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