RFR: Use one future [v3]

[Alan Bateman]

On Fri, 15 Apr 2022 17:14:25 GMT, Paul Sandoz <psandoz at openjdk.org> wrote:

>> Here's an example of changing the structured task scope impls, using one `Future` field and comparing future states. In effect the state can only increase monotonically (as per the order determined by the comparator).
>> 
>> The single future field could be made non-volatile, using the `VarHandle` for the volatile read in `handleComplete` since the happens-before edge should ensure the future is visible to the reading thread after `join`.
>
> Paul Sandoz has updated the pull request incrementally with one additional commit since the last revision:
> 
>   Switch expression style update.
>   
>   (No support in IntelliJ yet for such reformatting.)

Marked as reviewed by alanb (Committer).

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PR: https://git.openjdk.java.net/loom/pull/144