AbstractOnSubscribe fast path?

[davidmoten]

I'm a huge fan of AbstractOnSubscribe because has made implementing backpressure so much easier. In the case that I have a fast path I'd like to specify it to AbstractOnSubscribe so that one OnSubscribe handles both cases. Any thoughts? (@akarnokd)

[benjchristensen]

What do you mean by fast path?

[davidmoten]

By fast path I mean non-backpressure supporting code that is run when Long.MAX_VALUE is requested. For my custom operator it's significantly faster than the backpressure supporting AbstractOnSubscribe.

[akarnokd]

At first glance, the drawback for it is that you need to specify two separate logic for emitting values: one would be based on phases the other on free-form onXXX calls.

[davidmoten]

Yeah it's a drawback but in my cases the challenge in writing the OnSubscribes has been mostly handled by AbstractOnSubscribe. The non-backpressure OnSubscribe is a cinch so not a lot of overhead for big performance gains. Perhaps a decent performance improvement would be achieved with @benjchristensen 's batching suggestion in #2801.

[akarnokd]

I'll work this out tomorrow along with #2801 since they are somewhat related.

[akarnokd]

See #3118.