java.sql2 Connection.connect(Function<Throwable, Void>) should be connect(Consumer<Throwable>)

[Lukas Eder]

Hello,

I'm referring to this version:
http://hg.openjdk.java.net/jdk10/sandbox/jdk/file/a31057bda7c5/src/java.sql/share/classes/java/sql2

Which I believe to be the latest version on that branch. There's a method
Connection.connect(Function<Throwable, Void>) which I think has two issues:

1. It should accept a Consumer<Throwable>, just like Operation.onError(). I
don't see the point of having a Function<Throwable, Void> here. It looks
like this is just because of an implementation detail leaking into the API.
The implementation should be:

  public default Connection connect(Consumer<Throwable> onError) {
    this.holdForMoreMembers()
            .submit();
    this.connectOperation()
            .submit()
            .toCompletableFuture()
            .exceptionally(t -> { onError.accept(t); return null; });
    return this;
  }

Instead of:

  public default Connection connect(Function<Throwable, Void> onError) {
    this.holdForMoreMembers()
            .submit();
    this.connectOperation()
            .submit()
            .toCompletableFuture()
            .exceptionally(onError);
    return this;
  }

2. This may be my incomplete understanding of the API in general, but from
what I understand, there might be a race condition between the submit()
operation, and the transformation to a CompletableFuture and the error
interception. Can this API really *guarantee* that all errors will be
passed to the "onError" handler even if submit() terminates super fast?

If not, this might be a flaw in the Submission.toCompletableFuture() method.

Thanks,
Lukas