RFR: 8277090 : jsr166 refresh for jdk19 [v2]

[Doug Lea]

On Tue, 3 May 2022 20:04:48 GMT, Paul Sandoz <psandoz at openjdk.org> wrote:

>> src/java.base/share/classes/java/util/concurrent/CompletableFuture.java line 2153:
>> 
>>> 2151: 
>>> 2152:     @Override
>>> 2153:     public Throwable exceptionNow() {
>> 
>> The unwrapping of CompletionExceptions should be documented
>
> `exceptionNow` is specified to call `get`, which does not throw `CompletionException`:
> 
>      * @implSpec
>      * The default implementation invokes {@code isDone()} to test if the task
>      * has completed. If done and not cancelled, it invokes {@code get()} and
>      * catches the {@code ExecutionException} to obtain the exception.

As (almost) mentioned by others, this is legal because CompletionException is a RuntimeException, and would not be unexpected by CompletableFuture users. (The rules for when it is used have a designed-by-committee feel, because they were!)

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PR: https://git.openjdk.java.net/jdk/pull/8490