Chris Hegarty said the following on 06/17/11 02:37:
On 06/16/11 05:32 PM, Mike Duigou wrote:
Hi Chris;
The getClass() seems unnecessary. Why not :
public Random(long seed) {
this.seed = new AtomicLong();
setSeed(seed);
}
or
private final AtomicLong seed = new AtomicLong();
public Random(long seed) {
setSeed(seed);
}
Both of these would seem to have the same effect without needing to do
the explicit class check.
The change ( originally from Martin ) tries to save a couple of volatile
writes in the common case. Yes, it's not a pretty as it could be.
But is the getClass + check + branch cheaper than those volatile writes?
I know the history is somewhat convoluted here and the real problem was
caused by trying to define a subclass (ThreadLocalRandom) of Random that
stripped away Random's thread-safety mechanisms. You not only end up
with redundant state (two seeds!) but it breaks type substitutability. :(
But the milk has been spilt here and right now we just need to have TLR
properly initialize its local seed. So its a thumbs up from me.
David
