RFR: 7902982: jcstress: Add samples for some mutex algorithms [v8]

[Michael Mirwaldt]

On Tue, 29 Jun 2021 15:04:52 GMT, Aleksey Shipilev <shade at openjdk.org> wrote:

>> jcstress-samples/src/main/java/org/openjdk/jcstress/samples/concurreny/mutex/Mutex_04_AtomicBoolean.java line 58:
>> 
>>> 56:     @Actor
>>> 57:     public void actor1(II_Result r) {
>>> 58:         while(!canEnterCriticalSection.compareAndSet(true, false)) ;
>> 
>> Suggestion:
>> 
>>         while (!canEnterCriticalSection.compareAndSet(true, false)); // spin
>
> ...and should probably take the [TTAS](https://en.wikipedia.org/wiki/Test_and_test-and-set) form:
> 
> 
>    while (taken.get() || !taken.compareAndSet(false, true)); // spin

Done

-------------

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