Hi, Doug's explanation provides an excellent hook to hang the RFR off:
http://cr.openjdk.java.net/~psandoz/tl/JDK-8020291-completion-stage/specdiff/overview-summary.html http://cr.openjdk.java.net/~psandoz/tl/JDK-8020291-completion-stage/webrev/ Paul. On Jul 11, 2013, at 12:29 PM, Doug Lea <d...@cs.oswego.edu> wrote: > > Last fall, when putting together class CompletableFuture, and when > many issues surrounding lambdas and Streams were still up in the air, > we postponed dealing with the question of how to extract out an > interface that would support usages by those who need the fluent > completion-style capabilities, but under different policies or > mechanisms that cannot otherwise be captured using a single class. The > lack of an interface was a serious problem because the variation among > policies and methods beyond the base fluent methods is so wide and > conflicting that some potential users wrote off CompletableFuture as > unusable -- some need method X, some cannot allow that same method X, > for X dealing with cancellation, blocking, overwrites, etc. > > We finally last week settled this in an acceptable and simple way, > introducing interface CompletionStage, that is nearly just a subset of > existing CompletableFuture methods, and adjusting CompletableFuture > accordingly, in a way that provides a recipe for creating > interoperable CompletionStage implementations that may differ wrt > those methods not in the CompletionStage interface. The adjustments > are small but still officially require CCC approval. We had to > introduce a method form ("whenComplete") to deal with exceptional > completions that otherwise required use of CompletableFuture-dependent > methods. Plus a couple of utilities and some spec rewordings, and an > overhaul of CompletableFuture class-level documentation to now > reference CompletionStage. > > After expert-group and concurrency-interest discussions, no one > disagrees that this is an improvement. Some people have lingering > disagreements about those policy issues, but are more content that > there is now a straightforward way of obtaining the ones they want. > > The updates have also been in lambda repo (although probably not used > much) for about a week. > > Paul Sandoz has volunteered to coordinate the CCC and webrev > and will post the details. (Thanks Paul for adding this > to your already overcomitted workload!) > > -Doug > >
