Re: CompletableFuture#postComplete() can be invoked concurrently?

Thanks to Alex and Martin for pointing out that this case cannot arise. 
It would be great if we could have full mechanical proofs of such 
things. People out there occasionally work on these for j.u.c 
components, but they always lag development by a long time. In the mean 
time, we should improve internal algorithm documentation.

On 8/23/20 3:09 AM, Alex Otenko via Concurrency-interest wrote:
> Besides, first need to show reachability of that state.
>
> So you have src.result set. Concurrent invocations of 
> d.completeThrowable vs d.completeValue are possible only if two 
> threads can see different src.result or different src.result.ex.
>
> I don't see a path to reach this necessary condition.
>
> Alex
>
> On Sun, 23 Aug 2020, 08:03 Martin Buchholz, <[email protected] 
> <mailto:[email protected]>> wrote:
>
>          * Method postComplete is called upon completion unless the target
>          * is guaranteed not to be observable (i.e., not yet returned or
>          * linked). Multiple threads can call postComplete, which
>
>     On Sat, Aug 22, 2020 at 11:53 PM Liu <[email protected]
>     <mailto:[email protected]>> wrote:
>     >
>     > In my first post, There is the special thread execution order.
>     >
>     > high level outcome is:
>     > two thread will invoke CompletableFuture#postComplete()
>     > on same object concurrently.
>     >
>     > expected outcome:
>     > only one thread can invoke CompletableFuture#postComplete()
>     > on a object.
>     >
>     > like I said, in CompletableFuture.UniApply#tryFire(),
>     > d.completeThrowable(x, r); and dep = null;
>     > are not a atomic operation. The gap between two codes
>     > may cause high level outcome.
>     >
>     > PS:when dep == null, it means current Completion Object
>     > has been done.
>     >
>     > PPS: CompletableFuture#postComplete() seems not design to be
>     > invoked on same object.
>     >
>     >
>
>
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