Re: [infinispan-dev] keySet(), values() and entrySet() not implemented

Mircea Markus wrote: > Galder Zamarreno wrote: >> Hi, >> >> keySet(), values(), entrySet() do not seem to be implemented at >> the moment: >> >> public Set<K> keySet() { >> throw new UnsupportedOperationException("TODO implement >> me"); // TODO implement me >> } >> >> public Collection<V> values() { >> throw new UnsupportedOperationException("TODO implement >> me"); // TODO implement me >> } >> >> public Set<Map.Entry<K, V>> entrySet() { >> throw new UnsupportedOperationException("TODO implement >> me"); // TODO implement me >> } >> >> We should be implementing these methods, shouldn't we? Users might >> want to iterate the map for example to print the contents or to >> verify it contains what they put on it...etc. >> >> I can't see a JIRA for it, so I'll open one so that this gets >> implemented for Beta1 unless someone has any objections. >> >> On IRC, Mircea said it might very costly, specially for dist, but >> we still need it regardless, otherwise we're not fully >> implementing the ConcurrentMap interface and these are commonly >> used methods. > for DIST these might be implemented as follows: > -the node broadcasts a 'GetKeys' command to all others nodes in the > cluster > - on remote nodes locks are acquired for all keys (not sure this > mandatory though) > - each node responds with the set of keys > - calling node puts them together and returns them to the user > for entrySet this is even more costly, as all cluster state shall > be transfered to the calling node. > Now, what worries me is the fact that users might overuse these > methods, without being aware of the performance consequences. > A possible way to enforce the users to acknowledge that these > operations are costly, is to disable them by default and allow a > config element to enable them. I don't like the idea of having a public API method disabled by default. Instead, I think we should warn users when calling these methods with DIST mode on.