RFR: ClassicProblem_02_ProducerConsumerProblem - third try

[Michael Mirwaldt]

On Sun, 14 Nov 2021 22:56:25 GMT, Michael Mirwaldt <duke at openjdk.java.net> wrote:

> This sample implements some solutions from the wikipedia article about the producer-consumer-problem on https://en.wikipedia.org/wiki/Producer%E2%80%93consumer_problem .
> It contains these solutions:
> - _OneProducerOneConsumer_ with semaphores
> - _FlawedTwoProducersOneConsumer_ with semaphores in which the producers sometimes use the same index for their items and overwrite each others item in the buffer
> - _FixedTwoProducersOneConsumer_ with semaphores which uses an extra lock for the index so that the producers never use the same index for their items
> - _Lock_ doesn't use any sempahores but a reentrant lock with two conditions. It supports many producers and many consumers
> - _AtomicIntegers_ neither uses any semaphores but two atomic integers and supports one producer and one consumer.
> 
> I have decided not to implement the last solution with finite-range single writer registers in the wikipedia article. It looked far too complicated to me.
> 
> This is my third try to avoid squash commits.

This PR looks much better now. Thanks for the advice, @shipilev .
I will do my next PRs that way, too.

Can you review this samples, please, @shipilev?

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PR: https://git.openjdk.java.net/jcstress/pull/104