Netflix/RxJava — pull request #1412 by benjchristensen (2014-07-07 22:46:08+00:00)
Title: Backpressure & 0.20.0-RC1

This is a functioning implementation of backpressure. Of the major unbounded queue operators in 0.19, this implements `observeOn` and `merge` but not yet `zip`.

### New Signatures

```java
public interface Producer {
public void request(int n);
}
```

```java
public abstract class Subscriber implements Observer, Subscription {

/**
* Optionally called from `Observable.OnSubscribe`.
*/
public final void setProducer(Producer producer);

/**
* Allow implementing classes to capture, decorate or override the `Producer` without affecting the `Subscriber` logic.
*/
protected Producer onSetProducer(Producer producer);

public final void request(int n);
}
```