> Local cache is local to a data context (right?). But currently the
> application creates a new datacontext for every "transaction", so if I
> understood correctly the local cache is useless and I should use the shared
> cache.
Correct.
> I also tried to add a listener (on postPersist, postUpdate and postRemove) to
> clear the cache for that particular group, but it does not work:
>
> private void clearCache(Object entity) {
> Persistent object = (Persistent)entity;
> QueryCache cache =
> ((BaseContext)object.getObjectContext()).getQueryCache();
> cache.removeGroup(object.getClass().getName());
> }
This is going in the right direction. So is listener method invoked, but the
cache is not cleared, or the listener method is never invoked.
BTW Cayenne 3.1 has a nice set of extensions called cayenne-lifecycle. The docs
are still sparse (we are working on those), but there is a @CacheGroups
annotation placed on persistent classes that tells Cayenne that any changes to
a given type of objects should generate a cache invalidation event. E.g.:
@CacheGroups("news")
public class News extends com.foo.auto._News { }
processing of this annotation is enabled by installing
org.apache.cayenne.lifecycle.cache.CacheInvalidationFilter (also part of
cayenne-lifecycle):
DataChannelFilter filter = new CacheInvalidationFilter();
CayenneRuntime runtime = ...
// a bit clunky.. may merge the following 2 lines in one in the future releases:
runtime.getDataDomain().addFilter(filter);
runtime.getDataDomain().getEntityResolver().getCallbackRegistry().addListener(filter);
Cheers,
Andrus
On Aug 21, 2012, at 6:36 PM, Francesco Romano wrote:
> Hi everybody.
>
> I'm trying to add caching support (query cache) to a project which uses
> cayenne.
> For what I understood in the online documentation there are two types of
> caches: local and shared.
> Local cache is local to a data context (right?). But currently the
> application creates a new datacontext for every "transaction", so if I
> understood correctly the local cache is useless and I should use the shared
> cache.
>
> Now... the problem.. I have a query cached (a sort of select * from table)
> and a new row is added in the table. I would like that the next time the same
> query is called also the new row is fetched.
>
> This is the query cache
>
> SelectQuery select = new SelectQuery(t);
> Class t; //this is the class of the persistent object to be fetched
> select.setCacheStrategy(QueryCacheStrategy.SHARED_CACHE);
>
> select.setCacheGroups(t.getName());
>
> This is my "sample" test code (Network is a Cayenne Object class)
> (GetAllNetwork is a selectquery with the above caching. AddNetwork adds a new
> object and commit it. A new DataContext is used every time)
>
> List<Network> networks = dbHandle.GetAllNetwork();
> Network net = dbHandle.AddNetwork();
> List<Network> newNetworks = dbHandle.GetAllNetwork();
>
> assertEquals(networks.size() + 1, newNetworks.size());
>
>
> Now... my assert is not true, because the query is cached.
> I also tried to add a listener (on postPersist, postUpdate and postRemove) to
> clear the cache for that particular group, but it does not work:
>
> private void clearCache(Object entity) {
> Persistent object = (Persistent)entity;
> QueryCache cache =
> ((BaseContext)object.getObjectContext()).getQueryCache();
> cache.removeGroup(object.getClass().getName());
> }
>
> Any help?
>
> Thanks
> Regards
>
> Francesco Romano
>
