RFR: CODETOOLS-7903060: jcstress: ProducerConsumer problem sample [v8]

[Vladimir Sitnikov]

On Fri, 10 Dec 2021 14:12:11 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.
>
> Michael Mirwaldt has updated the pull request incrementally with one additional commit since the last revision:
> 
>   applied proposals from the fifth review on sample Classic_02_ProducerConsumerProblem

jcstress-samples/src/main/java/org/openjdk/jcstress/samples/problems/classic/Classic_02_ProducerConsumerProblem.java line 137:

> 135:         @Arbiter
> 136:         public void fake(Z_Result r) {
> 137:             r.r1 = true;

@mmirwaldt , It does not seem to be good to have "all outcomes are acceptable".

Have you considered producing messages with different **values** so you can tell which one was consumed?

For instance: `r1=produce(1); r2=produce(2);` and then `r3=consume(); r4=consume();`.

Then you could verify:
1) "1, 2, 1, 2" is acceptable
2) all others states are forbidden.

The same would apply to the other samples.

WDYT?

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