EntryProcessor should be able to access other entries that are on the same Partition.

[fuadm]

It would be nice if we “from an entryprocessor” could also modify entries in related maps on the same partition. Lets say you have an “order” map and an “order items” map with a partitionaware key related to the order. You may also want to update the order items (as a separate map) under the same lock.

We have one thread per partition, that makes the implementation easier. This way one can do an atomic operation that spans multiple data structures on the same Partition.

[mdogan]

It's already possible to access / modify data on the same partition. You
can try and see..

[fuadm]

how? do you have a code sample? I couldn't see it? Can I just access the IMap?

[mdogan]

https://github.com/hazelcast/hazelcast/blob/master/hazelcast/src/test/java/com/hazelcast/map/EntryProcessorTest.java#L283

~Sent from mobile

[ChristerF]

Cool, would this trigger entrylisteners for the other map properly too?

[ChristerF]

I just tested this and I get an error:
ERROR [2013-10-10 21:15:48,959] com.hazelcast.map.operation.EntryOperation: [192.168.210.38]:5701 [dev] Thread[hz._hzInstance_1_dev.operation.thread-5,5,_hzInstance_1_dev] cannot make remote call: PutOperation{mixerChannels}
! java.lang.IllegalThreadStateException: Thread[hz._hzInstance_1_dev.operation.thread-5,5,_hzInstance_1_dev] cannot make remote call: PutOperation{mixerChannels}

[mdogan]

Can you post your code?

~Sent from mobile

[ChristerF]

Simplified version of what I want to do.

Basically two maps, sessions and channels, where channels belong to sessions. The "channel" key is a PartitionAwareKey and I want to store a channel atomically with the storage of the session, while keeping them in separate maps. I also want to make sure that Events are generated for the "channel" map I touch.

Here is some abbreviated code:

import com.google.common.base.Optional;
import com.hazelcast.core.HazelcastInstance;
import com.hazelcast.core.HazelcastInstanceAware;
import com.twilio.mixerstate.hazelcast.AbstractEntryProcessor;

import java.util.Map;
public class AllocateChannelForMixerEntryProcessor extends AbstractEntryProcessor implements HazelcastInstanceAware {
private HazelcastInstance hzi;

public AllocateChannelForMixerEntryProcessor() {

}

@Override
public Object process(Map.Entry entry) {
    if (entry.getValue() == null) {
            addToChannelMap(channel,hzi);
            entry.setValue("TEST");
   return session;

    }
}

private void addToChannelMap(String value,MyPartitionAwareKey , HazelcastInstance hzi) {
    IMap<MyPartitionAwareKey, String> channelMap = hzi.getMap("mixerChannels");
    channelMap.put(Id,value);
}

@Override
public void setHazelcastInstance(HazelcastInstance hazelcastInstance) {
    this.hzi = hazelcastInstance;
}

}

[fuadm]

Christer,

Can you try the following:

Test testMapEntryProcessorPartitionAware() in https://github.com/hazelcast/hazelcast/blob/master/hazelcast/src/test/java/com/hazelcast/map/EntryProcessorTest.java

[ChristerF]

Fuad and Mehmet,
I have now verified that it works to call an EntryProcessor for another map as long as it ends up in the same partition - just as your unit test is showing.

That solves my immediate concern, thanks!

Now - a question: What about the backup-operations? Will they be happening one by one for each invoked EntryProcessor on that thread? Preferably this would be "batched" up such that there is only one roundtrip for the backup operations.

Thanks,
Christer

[mdogan]

Currently backup ops are executed one by one.