RFR: CODETOOLS-7903060: jcstress: ProducerConsumer problem sample [v3]

[Michael Mirwaldt]

> 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.

Michael Mirwaldt has updated the pull request with a new target base due to a merge or a rebase. The pull request now contains three commits:

 - Merge branch 'openjdk:master' into ClassicProblem_02_ProducerConsumerProblem-3
 - applied proposals from first review on sample ClassicProblem_02_ProducerConsumerProblem
 - created first draft of sample ClassicProblem_02_ProducerConsumerProblem

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Changes: https://git.openjdk.java.net/jcstress/pull/104/files
 Webrev: https://webrevs.openjdk.java.net/?repo=jcstress&pr=104&range=02
  Stats: 316 lines in 1 file changed: 316 ins; 0 del; 0 mod
  Patch: https://git.openjdk.java.net/jcstress/pull/104.diff
  Fetch: git fetch https://git.openjdk.java.net/jcstress pull/104/head:pull/104

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