Re: ability to get multiple elements with a single method call

Thanks.  I committed this patch.  I made a few small
changes.

note:
- I found an extra semi colon.  This would break with
some compilers.
- I improved the comment on foundprunekeys in
CompiteCache. 
- The lateral concurrent test was not named with a
unit suffix, because it is not a unit test.  This one
is too slow.
- If you change the project.xml you have to change the
pom.xml too.

Aaron

--- Chris Fairbanks <[email protected]> wrote:

> In order to help optimize for network latency when
> dealing with distributed
> cache servers, I'd like to add the ability to fetch
> multiple cache elements
> at once from a JCS cache.  I've done the following
> by adding a
> getCacheElements method which takes in a Set of keys
> and returns a map of
> key->cached value.
> 
> The logic in each implementation goes as follows,
> for the most part: iterate
> over the set of keys and call out to the
> already-existing get method, then
> put the results into a map based on the key, then
> return it.  I didn't do
> any optimization like bundling the MySQL calls into
> a single get query with
> multiple key values, although that would be an
> obvious followup.  When
> relevant (as in the CacheAccess class),
> getCacheElements simply calls out to
> getMultiple on its ICache instance.
> 
> I'm attaching a diff patch with the changes I made
> in order to achieve
> this.  It's almost entirely additional methods, plus
> some javadocs cleanup
> where I saw problems.  We've been using this code in
> locally-compiled jar
> form in our development environment for some time
> now without negative
> impact, but we'd like to get it into the main JCS
> build if possible.
> 
> Thanks,
> Chris Fairbanks
> 
> In ICacheAccess interface:
> 
>     /**
>      * Get multiple elements from the cache based on
> a set of cache keys.
>      * <p>
>      * This method returns the ICacheElement wrapper
> which provides access
> to element info and other
>      * attributes.
>      * <p>
>      * This returns a reference to the wrapper. Any
> modifications will be
> reflected in the cache. No
>      * defensive copy is made.
>      * <p>
>      * This method is most useful if you want to
> determine things such as
> the how long the element
>      * has been in the cache.
>      * <p>
>      * The last access time in the ElementAttributes
> should be current.
>      * <p>
>      * @param names set of Object cache keys
>      * @return a map of Object key to ICacheElement
> element, or empty map if
> none of the keys are present
>      */
>     Map getCacheElements( Set names );
> 
> In ICache interface:
> 
>     /**
>      * Gets multiple items from the cache based on
> the given set of keys.
>      * <p>
>      * @param keys
>      * @return a map of Serializable key to
> ICacheElement element, or an
> empty map if there is no data in cache for any of
> these keys
>      * @throws IOException
>      */
>     Map getMultiple( Set keys )
>         throws IOException;
> 
> In ICacheService interface:
> 
>     /**
>      * Gets multiple items from the cache based on
> the given set of keys.
>      * <p>
>      * @param cacheName
>      * @param keys
>      * @return a map of Serializable key to
> ICacheElement element, or an
> empty map if there is no data in cache for any of
> these keys
>      * @throws ObjectNotFoundException
>      * @throws IOException
>      */
>     Map getMultiple( String cacheName, Set keys )
>         throws ObjectNotFoundException, IOException;
> >
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