RFR: 8257876: Avoid Reference.isEnqueued in tests [v2]

[Thomas Schatzl]

On Thu, 10 Dec 2020 09:01:54 GMT, Kim Barrett <kbarrett at openjdk.org> wrote:

>> Please review this change that eliminates the use of Reference.isEnqueued by
>> tests.  There were three tests using it:
>> 
>> vmTestbase/gc/gctests/ReferencesGC/ReferencesGC.java
>> vmTestbase/gc/gctests/WeakReferenceGC/WeakReferenceGC.java
>> jdk/java/lang/ref/ReferenceEnqueue.java
>> 
>> In each of them, some combination of using Reference.refersTo and
>> ReferenceQueue.remove with a timeout were used to eliminate the use of
>> Reference.isEnqueued.
>> 
>> I also cleaned up ReferencesGC.java in various respects.  It contained
>> several bits of dead code, and the failure checks were made stronger.
>> 
>> Testing:
>> mach5 tier1
>> Locally (linux-x64) ran all three tests with each GC (including Shenandoah).
>
> Kim Barrett has updated the pull request incrementally with one additional commit since the last revision:
> 
>   move REMOVE and RETAIN decls and init

Also good with deferring the changes to the comments and the move of the statics.

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

Marked as reviewed by tschatzl (Reviewer).

PR: https://git.openjdk.java.net/jdk/pull/1691