How to get the entry value in a Listener?

[jmfaerman]

I am experimenting with Listeners and noted that when @CacheEntryCreated i don't have access to the entry value, even when pre=false

My log reads:

CacheEntryCreated size[0] pre[true] key[0c738668-079f-4f76-b9df-f7b416eb4188]

CacheEntryCreated size[0] pre[false] key[0c738668-079f-4f76-b9df-f7b416eb4188]

Is it possible to evaluate the value being put into the cache?

Also, i could not understand why a single event fires the listener twice (pre=true / pre=false), forcing every listener to check. Why is this so?

[matlach]

Hello Julio,

it's not possible to get cache value directly in the event (I don't know why tough, maybe you should fill an enhancement request about it).

but i guess you can access it quite easily like this :

@CacheEntryCreated 
public void onCacheEntryCreated(CacheEntryCreatedEvent<String, String> event){
    String value = event.getCache().get(event.getKey());
}

for the 'pre' stuff, it's has been already proposed in : https://issues.jboss.org/browse/ISPN-893

feel free to vote for the issue like i already did

hope this helps,

[galder.zamarreno]

@Mathieu, thanks for the reply, but that won't work: https://docs.jboss.org/author/pages/viewpage.action?pageId=5832860

The big problem with CacheEntryCreated, is that it's not easy to get hold of the entry when the entry has been created.

You have to implement @CacheEntryModified, which also gets fired when the entry is created.

So, how do u differentiate between a create and update with @CacheEntryModified? You can do so when isPre=true, cos event.getValue() would return null if the entry is created.

This area is very fuzzy and as I already highlighted, not very intuitive: http://lists.jboss.org/pipermail/infinispan-dev/2012-February/010272.html

We will be moving towards JSR-107 style notifications soon, so we're deferring any work till then.

[galder.zamarreno]

The isPre() is to allow you to act before, or after the event. Remember that listeners can veto operations, so you could veto a put before the event has actually happened.

[jmfaerman]

Tanks guys, making it clear:

when CacheEntryModified AND pre=false

then the value can be retrieved directly from the event (not from the cache).

And that raises a related question... why is the cache size the same when pre=true and pre=false?

Shouldn't size(pre=false) == size(pre=true) +1 ?

[galder.zamarreno]

Re: size: You have a point there. Mind creating a JIRA in https://issues.jboss.org/browse/ISPN and attach any test case you might have?

[jmfaerman]

Sure, here it is: https://issues.jboss.org/browse/ISPN-2054

Unfortunately, i do not know ispn code enough yet to solve this, if it is an issue at all, but would be glad do help anyhow.