Re: Making one or more threads wait for another to produce a value or fail

From:
Patricia Shanahan <pats@acm.org>
Newsgroups:
comp.lang.java.programmer
Date:
Tue, 31 May 2011 10:39:28 -0700
Message-ID:
<4KOdncWZ14NTunjQnZ2dnUVZ_hCdnZ2d@earthlink.com>
On 5/31/2011 10:08 AM, Paul Cager wrote:

On May 31, 5:06 pm, Patricia Shanahan<p...@acm.org> wrote:

One way to do the synchronization would be a semaphore that is initially
zero, but with a large number of permits added when Penelope calls a
setVerdict method. The getVerdict method that the suitors call would
wait to get a permit, record the verdict, and put the permit back so
there is no possibility of running out of permits.


Could you not subclass CountDownLatch and add a "verdict" property?


I would definitely not subclass CountDownLatch. If I were to use it, the
verdict delivery class would have a CountDownLatch reference as a field,
along with fields representing the verdict.

If you subclass CountDownLatch, or any other synchronization class, the
choice of synchronization method becomes visible to the suitors and
Penelope. They would be able to call all the CountDownLatch public
methods directly, so desk checking the synchronization would involve
checking all code with access to the subclass.

That said, I think CountDownLatch is a better choice than my semaphore
suggestion.

Patricia

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