Cache write-behind complete check

Question

Is there a surefire way to check a cache that has a store persisting objects to the database and write-behind set to 2 seconds, has persisted all objects put into the cache?
We have tried using JMX, querying the Cache's QueueSize and waiting until it reaches 0. It turns out that when putting objects into the write-behind cache, the write-behind queue is not necessarily non-zero immediately after the put(s). e.g. QueueSize may be 0, even if objects still need to be persisted.
For our nightly integration tests we need to clear out the cache, but want to make sure we do not call NamedCache.clear() on a cache that still has objects that need to be persisted.
Any ideas?

Answer 1

Hi Rob,
The problem may actually be the timeliness of updates to the QueueSize JMX attribute as we're using the MBeanConnector to obtain information on our cache members (and providers). Assuming that objects actually make it to the write-behind queue during the cache put call and certain tests need to be sure these objects are persisted, instead of doing the accounting approach discussed previously, I found a forum thread on ReadWriteBackingMap flush calls.
To get access to the ReadWriteBackingMap.flush() I created a small test today using a subclass of ReadWriteBackingMap that registers the backingmap with our CashStore implementation:
    protected void configureCacheStore(CacheStore store, boolean readOnly) {
        super.configureCacheStore(store, readOnly);
        if (store instanceof CacheLoaderWriterProvider) {
            ((CacheLoaderWriterProvider)store).registerBackingMap(this);
    }Our cachstore (CacheLoaderWriterProvider) in turn exposes a call to the registered map's flush method as a JMX operation.
Whenever we need to be sure the write-behind queue is empty during our tests, we'll call this JMX operation.
Best Regards,
Marcel.