Synching of DataCache with QueryCache outside of a transaction
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Key: OPENJPA-1448
URL: https://issues.apache.org/jira/browse/OPENJPA-1448
Project: OpenJPA
Issue Type: Sub-task
Components: datacache
Affects Versions: 2.0.0-M3
Reporter: Kevin Sutter
Priority: Minor
One of the tests (CacheTest.testQueryImplicitEvictions) re-enabled for the
parent JIRA (openjpa-1443) expected that the DataCache would automatically
synch up with the QueryCache, even outside of a transaction. This test would
first load up the DataCache with Entity instances. Then, a Query would be
created and executed against these Entities to create an entry in the
QueryCache. Then, using implicit eviction processing, those target Entities
were removed from the DataCache. The expectation was that this implicit
eviction would also clean up the QueryCache so that the Query and Results were
no longer present.
It doesn't look like our synchronization between the DataCache and QueryCache
work that way. We will do synchronization when a "dirty" transaction
completes. That is, if you have updated or deleted Entities that exist in the
DataCache, when that transaction completes, we will do a synch with the
QueryCache to remove stale Queries and Results. But, we don't do this
synchronization on every eviction.
Maybe Kodo did and that's why this testcase exists? Not sure. To be honest,
I'm concerned about this type of synchronization from an overhead perspective.
If every eviction required us to scour the QueryCache for a potential stale
Result, we might be chewing up a lot of resources. But, since this previously
disabled testcase expected this capability, I thought I would write a
low-priority JIRA to track the issue. Here are my comments from the
CacheTest.testQueryImplicitEvictions method:
/*
* Not a valid test... At least not with the current
implementation...
*
* Just removing items from the DataCache (as done via the previous
loop) is not sufficient
* to remove the entries from the QueryCache. Currently, this
notification is done at the end
* of a transaction after inserts, updates, and deletes have been
performed. Then, the
* updateCaches() method is invoked on the DataCacheStoreManager
which will flow the request to
* the QueryCache. With no direct updates to the "Entities of
interest", then there's nothing to
* flow over to the QueryCache for cleanup. Even putting the above
loop within a transaction is
* not sufficient, since there have been no updates to the
"Entities of interest".
*/
// em = factory.createEntityManager();
// broker = JPAFacadeHelper.toBroker(em);
// q = broker.newQuery(JPQLParser.LANG_JPQL, "Select a FROM "
// + CacheObjectJ.class.getSimpleName()
// + " a where a.str = 'h'");
// try {
// assertInCache(q, null);
// }
// catch (AssertionFailedError e) {
// bug(626, "query cache invalidation is broken");
// }
Thanks,
Kevin
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