RFR: 7902982: jcstress: Add samples for some mutex algorithms [v3]

[Vladimir Sitnikov]

On Tue, 29 Jun 2021 12:46:42 GMT, mmirwaldt for openjdk <github.com+86246875+mmirwaldt-openjdk at openjdk.org> wrote:

>> I have implemented 3 more samples:
>> *) the NoAlgorithm sample should show users of JCStress how they can define a critical section in a simple way
>> *) one sample for the Peterson's algorithm 
>> *) one sample for the Dekker's algorithm 
>> I have translated the pseudo code implementations of the English wikipedia articles into Java.
>> I have also tried out those examples: they compile and they run without any problems.
>
> mmirwaldt for openjdk has updated the pull request incrementally with one additional commit since the last revision:
> 
>   removed ids for forbidden outcomes

jcstress-samples/src/main/java/org/openjdk/jcstress/samples/concurreny/mutex/Mutex_01_NoAlgorithm.java line 51:

> 49: @State
> 50: public class Mutex_01_NoAlgorithm {
> 51:     private volatile boolean taken1, taken2;

volatiles must not be here.

jcstress-samples/src/main/java/org/openjdk/jcstress/samples/concurreny/mutex/Mutex_02_PetersonAlgorithm.java line 56:

> 54:     private final AtomicBoolean flagForActor2 = new AtomicBoolean();
> 55:     private final AtomicInteger turn = new AtomicInteger();
> 56:     private volatile boolean taken1, taken2;

`flagForActor1`, `flagForActor2`, and `turn` should be volatiles, taken1 and taken2 should be regular fields.

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PR: https://git.openjdk.java.net/jcstress/pull/85