Release 2.0.5

Author: akarnokd

CHANGES.md

@@ -2,6 +2,64 @@
 
 Version 1.x can be found at https://github.com/ReactiveX/RxJava/blob/1.x/CHANGES.md
 
+### Version 2.0.5 - January 27, 2017 ([Maven](http://search.maven.org/#artifactdetails%7Cio.reactivex.rxjava2%7Crxjava%7C2.0.5%7C))
+
+The most notable enhancement of this version is the inclusion of the `ParallelFlowable` API that allows parallel execution of a few select operators such as `map`, `filter`, `concatMap`, `flatMap`, `collect`, `reduce` and so on. Note that is a **parallel mode** for `Flowable` (a sub-domain specific language) instead of a new reactive base type. 
+
+Consequently, several typical operators such as `take`, `skip` and many others are not available and there is no `ParallelObservable` because **backpressure** is essential in not flooding the internal queues of the parallel operators as by expectation, we want to go parallel because the processing of the data is slow on one thread.
+
+The easiest way of entering the parallel world is by using `Flowable.parallel`:
+
+```java
+ParallelFlowable<Integer> source = Flowable.range(1, 1000).parallel();
+```
+
+By default, the parallelism level is set to the number of available CPUs (`Runtime.getRuntime().availableProcessors()`) and the prefetch amount from the sequential source is set to `Flowable.bufferSize()` (128). Both can be specified via overloads of `parallel()`.
+
+`ParallelFlowable` follows the same principles of parametric asynchrony as `Flowable` does, therefore, `parallel()` on itself doesn't introduce the asynchronous consumption of the sequential source but only prepares the parallel flow; the asynchrony is defined via the `runOn(Scheduler)` operator.
+
+```java
+ParallelFlowable<Integer> psource = source.runOn(Schedulers.io());
+```
+
+The parallelism level (`ParallelFlowable.parallelism()`) doesn't have to match the parallelism level of the `Scheduler`. The `runOn` operator will use as many `Scheduler.Worker` instances as defined by the parallelized source. This allows `ParallelFlowable` to work for CPU intensive tasks via `Schedulers.computation()`, blocking/IO bound tasks through `Schedulers.io()` and unit testing via `TestScheduler`. You can specify the prefetch amount on `runOn` as well.
+
+Once the necessary parallel operations have been applied, you can return to the sequential `Flowable` via the `ParallelFlowable.sequential()` operator.
+
+```java
+Flowable<Integer> result = psource.filter(v -> v % 3 == 0).map(v -> v * v).sequential();
+```
+
+Note that `sequential` doesn't guarantee any ordering between values flowing through the parallel operators.
+
+For further details, please visit the [wiki page](https://github.com/ReactiveX/RxJava/wiki/Parallel-flows) about Parallel flows. (New content will be added there as time permits.)
+
+**API enhancements**
+- [Pull 4955](https://github.com/ReactiveX/RxJava/pull/4955): add `sample()` overload that can emit the very last buffered item.
+- [Pull 4966](https://github.com/ReactiveX/RxJava/pull/4966): add `strict()` operator for strong Reactive-Streams conformance
+- [Pull 4967](https://github.com/ReactiveX/RxJava/pull/4967): add subjects for `Single`, `Maybe` and `Completable`
+- [Pull 4972](https://github.com/ReactiveX/RxJava/pull/4972): Improve `compose()` generics
+- [Pull 4973](https://github.com/ReactiveX/RxJava/pull/4973): Add `Completable.hide()`
+- [Pull 4974](https://github.com/ReactiveX/RxJava/pull/4974): add `Flowable.parallel()` and parallel operators
+- [Pull 5002](https://github.com/ReactiveX/RxJava/pull/5002): Add scheduler creation factories
+
+**Bugfixes**
+- [Pull 4957](https://github.com/ReactiveX/RxJava/pull/4957): fix `LambdaObserver` calling dispose when terminating
+- [Pull 4962](https://github.com/ReactiveX/RxJava/pull/4962): fix `takeUntil()` other triggering twice
+- [Pull 4970](https://github.com/ReactiveX/RxJava/pull/4970): fix `withLatestFrom` null checks, lifecycle
+- [Pull 4982](https://github.com/ReactiveX/RxJava/pull/4982): fix `Observable.concatMapEager` bad logic for immediate scalars.
+- [Pull 4984](https://github.com/ReactiveX/RxJava/pull/4984): fix cross-boundary invalid fusion with `observeOn`, `flatMap` & `zip`
+- [Pull 4987](https://github.com/ReactiveX/RxJava/pull/4987): Make `Observable.combineLatest` consistent with `Flowable`, fix early termination cancelling the other sources and document empty source case
+- [Pull 4992](https://github.com/ReactiveX/RxJava/pull/4992): `A.flatMapB` to eagerly check for cancellations before subscribing
+- [Pull 5005](https://github.com/ReactiveX/RxJava/pull/5005): `ExecutorScheduler.scheduleDirect` to report `isDisposed` on task completion
+
+**Other**
+- [Pull 4971](https://github.com/ReactiveX/RxJava/pull/4971): Add `@CheckReturnValue` to `create()` methods of `Subjects` + `Processors`
+- [Pull 4980](https://github.com/ReactiveX/RxJava/pull/4980): Update Copyright to 'RxJava Contributors'
+- [Pull 4990](https://github.com/ReactiveX/RxJava/pull/4990): Update marble diagrams for `sample()` overloads, Maybe and `Maybe.switchIfEmpty()`
+- [Pull 5015](https://github.com/ReactiveX/RxJava/pull/5015): Fix Reactive-Streams dependency to be `compile` in the library's POM
+- [Pull 5020](https://github.com/ReactiveX/RxJava/pull/5020): option to fail for using blockingX on the computation/single scheduler
+
 ### Version 2.0.4 - January 4, 2017 ([Maven](http://search.maven.org/#artifactdetails%7Cio.reactivex.rxjava2%7Crxjava%7C2.0.4%7C))
 
 **API enhancements**