[jboss-dev-forums] [Design of JBossCache] - Ordered maps in Nodes

[manik.surtani@jboss.com]

This is referring to:

	https://jira.jboss.org/jira/browse/JBCACHE-841

And rather than exposing the backing Map impl to users, I'd prefer to just provide a few settings on a node such that:

  | Node.isDataOrdered(); // tests if the data map is ordered
  | Node.isChildrenOrdered(); // tests if the child map is ordered
  | Node.setDataOrdered(boolean b); // locks the map, and then copies out the existing data map into a new ordered map structure
  | Node.setChildrenOrdered(boolean b); // similar to above
  | 
Is there anything else we'd need?  Using iterators on the sets and maps returned when accessing data/data-keys/children/children-names will be ordered if the node is set to be ordered.  I guess perhaps providing comparators if the data has no natural ordering would be useful?  This comparator would have to be serializable though if it is to be replicated/persisted.


  | Node.setDataComparator(Comparator<K> c);
  | 
I'm guessing we'd need a SortedMap similar to FastCopyHashMap that is optimised for copying/cloning?

Finally, these settings would have to be replicated/persisted.  I'm guessing there should be no special options on cache loaders, but when the data is loaded into the node it would be ordered by the map implementation.

Also, I see this as a per-node option.  Any thoughts on whether this would be useful as a cache-wide cfg option?  There may be cases where a thread is reading a node in a tx, and another thread sets it's sorted flag to true.  I'm guessing flag changes like these are considered a write operation since the map implementation changes and a copy of contents will take place.  Or - to make life easier - do we want this to be cache-wide so that all nodes are either sorted or not, and there is no issue with changing them?



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