[jboss-dev-forums] [Design of JBossCache] - Possible optimization of CachedSetImpl

[genman]

I was thinking that, instead of using a simple integer tag for each POJO in a Set, that you could incorporate the hash code (or part of it) along with a counter for objects that happened to have the same hash code, but not equal.

For example, the Set.contains() method could be written as:


  |    public boolean contains(Object o)
  |    {
  | 	  int hash = o.hashCode();
  |           Collection<Object> children = node.getChildrenNames();
  | 	  for (int i = 0; i < children.size(); i++) {
  | 		 Long key = new Long((long)hash | ((long)i << 32));
  | 		 Object o2 = ...get(key);
  | 		 if (o2 == null)
  | 			return false;
  | 		 if (o.equals(o2))
  | 			return true;
  | 	  }
  | 	  return false;
  |    }
  | 

Worst-case performance is O(N), best is O(1).

Set.remove() would mean more complication; you'd have to actually shift entries around to fix gaps, if there were any.

I could contribute this as a patch if it made sense.

One thing I wonder though is, does it hurt to use Integer in an FQN instead of a String? I didn't see any problems during tests... Long.toString() would be fine I guess but less efficient.

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