event.getOldValue() is null in entryUpdated

[nayr...@gmail.com]

When an entryUpdated event is triggered, the EntryEvent object that gets passed in returns null from getOldValue().

import com.hazelcast.map.listener.EntryUpdatedListener;

...

public class DataTable<E> implements EntryUpdatedListener<E, Entity> {

...

public void entryUpdated(EntryEvent<E, Entity> event) {
       
        Entity updatedEntity = event.getValue();
        Entity originalEntity = event.getOldValue();

        System.out.println(updatedEntity); // Service: dataServer LastUpdated: 2016-07-07 15:34:14.796
        System.out.println(originalEntity); // null
}

This was working as expected (getOldValue returns value prior to update) in version 2.6.10, but it does not work in 3.4 or 3.6.4.

Thank you

[Vassilis Bekiaris]

Hi,

how do you register your entry listener? The following listener works fine in Hazelcast 3.6.4, I can see both old and new value when updating an entry either via map.put or map.replace:

map.addEntryListener(new EntryUpdatedListener<Integer, String>() {
    @Override
    public void entryUpdated(EntryEvent<Integer, String> event) {
        System.out.println("old val: " + event.getOldValue() + ", new val: " + event.getValue());
    }
}, true);

Cheers!
Vassilis

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[nayr...@gmail.com]

Thanks for replying,

This is from the DataTable class:

Config config = getHazelcast().getConfig();

MapConfig mapConfig = config.getMapConfig(name);
mapConfig.setMaxIdleSeconds(0);
mapConfig.setTimeToLiveSeconds(0);
mapConfig.setEvictionPolicy(EvictionPolicy.NONE);
mapConfig.setBackupCount(3);

hazelcast.getMap(name).addEntryListener(this, true);

Thanks

[ih...@hazelcast.com]

Is it possible that there was no entry in the table and this would mean a null value when you performed IMap.put. In this case, it is OK to receive null as the old value. Can you verify this by doing a get before put?

Regards,

ihsan

[nayr...@gmail.com]

Doh! Turns out that in our DataTable.put function we were using IMap.set instead of IMap.put, so as stated in the Javadoc:

Warning:

This method breaks the contract of EntryListener. When an entry is updated by set(), it fires an EntryEvent with a null oldValue.

Thanks for the help

[nadimin...@gmail.com]

This saved my life..however, the maps were being set in a C++ client.

[İhsan Demir]

I understand that you are setting the map value from C++ client but just remember that for any key at the first put, you will always receive null for the oldValue since there was no old value prior to that put, right? So, it is a good practice to always do a null check.

Regards,

ihsan

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Ihsan Demir
Software Engineer, Clients Team
Mahir İz Cad. No:35, Altunizade, İstanbul 
ih...@hazelcast.com

skype: idemir

cell: +90-543-6512477

[Stodge]

Forgive my naive question, but why would you get an entryUpdated when you add an entry? Shouldn't it use the entryAdded callback?

I have the same problem.

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[Sertuğ Kaya]

If you're doing put/set for an entry which is already there, you will get an entryUpdated event instead of an entryAdded event.