Re: [infinispan-dev] Lambda Serialization

I now have a working branch that is using this for the new CacheStream interface [1]. With this it allows users to use a stream without needing any casts for any of the intermediate or terminal operations. Note I completely revamped the BaseStreamTest [2] So in that case every example a user can find online can be pretty much copy pasted without additional changes, which to me is HUGE.

Unfortunately this causes the API to bloat quite a bit and I had to add a bunch of Serializable* classes (ex. [3]). The former bloat issue seems acceptable to me, I had thought about making a new separate API, but it seems like it is unneeded to me. The latter issue I had tried defining the generics on the method itself but the compiler can't quite figure out which method to invoke still [4].

I am still planning on adding a CacheIntStream, CacheDoubleStream and CacheLongStream interfaces as well. Without those users would need to do casts on the subsequent primitive stream if they used any of the mapTo<Int|Double|Long> or flatMapTo<Int|Double|Long> methods. Another side benefit of this refactoring is we can easily add new operations to the stream interfaces. We could add approximation methods maybe that return after a certain timeout, histogram specific support among others. I am open to whatever people think they would want added here. Unfortunately, we can't easily add in a Map.Entry stream (similar to spark PairRDD) without redoing a bunch more of the APIs and I don't know if we have time to support that. Any feedback would be great, hoping to get this ironed out soon before API freeze :) Cheers, - Will [1] https://github.com/wburns/infinispan/tree/ISPN-6272 [2] https://github.com/wburns/infinispan/commit/09734d533a445df23df94f7a053b1... [3] https://github.com/wburns/infinispan/blob/ISPN-6272/core/src/main/java/or... [4] https://gist.github.com/wburns/dffe4f7543f68215f74b On Wed, Feb 17, 2016 at 8:39 AM William Burns <mudokonman(a)gmail.com&gt; wrote: > > Actually I have a PR that will go in before the 8.2 Final release that > uses this [1]. Specifically check out the ClusterExecutor interface. It > doesn't have the issues of streams with overloading existing methods, > however it adds both overloaded variants and you can see how the tests > invoke those. > > [1] https://github.com/infinispan/infinispan/pull/4008 > > > On Wed, Feb 17, 2016 at 3:23 AM Galder Zamarreño <galder(a)redhat.com&gt; > wrote: >> >> Hey Will, >> >> A very interesting discovery! >> >> Do you have a branch were you've tried this out? I'd like to play with it >> to see it in action and analyse the downsides more closely. >> >> Cheers, >> -- >> Galder Zamarreño >> Infinispan, Red Hat >> >> > On 9 Feb 2016, at 17:36, William Burns <mudokonman(a)gmail.com&gt; wrote: >> > >> > I wanted to propose a pretty simple way of making the lambdas >> > serializable by default that I stumbled upon while working on another issue. >> > >> > I noticed that in the method resolution of the compiler it does some >> > nice things [1]. To be more specific when you have 2 methods with the same >> > name but vary by argument types, it will attempt to pick the most "specific" >> > one. Specific in this case you can think of if I can cast one argument type >> > to the other but it can't be cast to this type, then this one is most >> > specific. >> > >> > Here is an example, given the following class >> > >> > interface SerializableFunction<T, R> extends Serializable, Function<T, >> > R> >> > >> > The stream interface already defines: >> > >> > Stream map(Function<? super T, ? extends R> mapper); >> > >> > But we could add this to the CacheStream interface >> > >> > CacheStream map(SerializableFunction<? super T, ? extends R> mapper); >> > >> > In this case you have 2 different map methods accessible from your >> > CacheStream instance. When passing a lambda the Java compiler will >> > automatically choose the most specific one (in this case the >> > SerializableFunction one since Function can't be cast to >> > SerializableFunction). This will then make the lambda automatically >> > Serializable. In this way nothing special has to be done (ie. explicit >> > cast) to make the instance Serializable. >> > >> > This allows anyone using our Cache interface to immediately get lambdas >> > that are Serializable when using Streams. >> > >> > The main problem however would be ambiguity because the Serialization >> > would only be applied assuming you are using a defined class of CacheStream >> > etc. Also this means there are 2 methods (but that seems fine to me), so it >> > could cause a bit of confusion. The non serialization method is still >> > helpful if people want to their own Externalizer, since their implementation >> > doesn't have to implement Serializable then. >> > >> > What do you guys think? It seems like a decent compromise to me. >> > >> > - Will >> > >> > >> > >> > >> > >> > [1] >> > https://docs.oracle.com/javase/specs/jls/se8/html/jls-15.html#jls-15.12.2.5 >> > >> > >> > _______________________________________________ >> > infinispan-dev mailing list >> > infinispan-dev(a)lists.jboss.org >> > https://lists.jboss.org/mailman/listinfo/infinispan-dev >> >> >> _______________________________________________ >> infinispan-dev mailing list >> infinispan-dev(a)lists.jboss.org >> https://lists.jboss.org/mailman/listinfo/infinispan-dev _______________________________________________ infinispan-dev mailing list infinispan-dev(a)lists.jboss.org https://lists.jboss.org/mailman/listinfo/infinispan-dev