Ole Husgaard wrote:
> + // Using the construct
> + // try {
> + // txCapsule.doSomething();
> + // } catch (NullPointerException ex) {
> + // throw new IllegalStateException("No transaction.");
> + // }
> + // may look like bad programming style, but it is needed to avoid to
> + // synchronize on these methods. If we used a construct like
> + // if (txCapsule == null)
> + // throw new IllegalStateException("No transaction.");
> + // txCapsule.doSomething();
> + // we can get spurious NullPointerExceptions when racing with the
> + // transaction completion.
> +
>
> public void commit()
> throws RollbackException,
> @@ -68,9 +83,11 @@
> java.lang.IllegalStateException,
> SystemException
> {
> - if( txCapsule == null )
> + try {
> + txCapsule.commit();
> + } catch (NullPointerException ex) {
> throw new IllegalStateException("No transaction.");
> - txCapsule.commit();
> + }
Interesting... Is this actually faster then synchronizing? Have you
measured it?
About a month ago I saw a presentation on Hot Spot and they claim that
the synchronized keyword has very little over head (something like 3
extra stack pushed and a lock grab), but exception handling like this
can be very expensive because Hot Spot purposely does not optimize
exception handling (which means that an exception can cost 100-1000
times longer then the non-excetion code).
The only way I could see that this code be faster is if there is a lot
of contention. Is there?
--
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Dain Sundstrom
Chief Architect JBossCMP
JBoss Group, LLC
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