Are put()'s to a replicated cache atomic?

Question

We are using Coherence for a storage application and we're observing what may be a Coherence issue with latency on put()'s to a replicated cache.
We have two software nodes on different servers sharing information in the cache and I need to know if I can count on a put() being atomic with respect to all software and hardware nodes in the grid.
Does anyone know if these operations are guaranteed to be atomic on replicated caches, and that an entry will be visible to ALL nodes when the put() returns?
Thanks,
Stacy Maydew

Answer 1

You could use explicit locking, for example,
if (cache.lock(key, timeout)) {
    try {
        Object value = cache.get(key);
        cache.put(key, value);
    } finally {
        cache.unlock(key);
} else {
    // decide what to do if you cannot obtain a lock
}Note that when using explicit locking, you will require multiple trips to the cache server: to lock the entry,
to retrieve the value, to update it and to unlock it. Which increases the latency.
You can also use an entry processor which carries the information needed for the update.
An entry processor eliminates the need for explicit concurrency control.
An example
public class KlantNaamEntryProcessor extends AbstractProcessor implements Serializable {
    public KlantNaamEntryProcessor() {
    public Object process(InvocableMap.Entry entry) {
        Klant klant = (Klant) entry.getValue();
        klant.setNaam(klant.getNaam().toLowerCase());
        entry.setValue(klant);
        return klant;
and it's usage
cache.invokeAll(filter, new KlantNaamEntryProcessor()).entrySet().iterator();Better examples can be found here: http://wiki.tangosol.com/display/COH33UG/Transactions,+Locks+and+Concurrency