Better compatibility with Ruby IO.

[ioquatix]

Fixes #23

[coveralls]

Coverage decreased (-0.3%) to 90.079% when pulling ded8a89 on blocking-read-write into d606979 on master.

[olleolleolle]

I read the PR and the long comment thread linked to this. Super clear.

A helpful thing in the write implementations is the “fast path” and “slow path” code comments. Keep them!

[olleolleolle]

(Is this commented-out code line meant to be there?)

[ioquatix]

Yeah, I sometimes use it for benchmarking different block sizes :p But I don't think it's suitable for release since it's a bit of a hack.

[ioquatix]

@olleolleolle thanks for your feedback.

One thing I think I've grown to accept, is that async-io is a huge hack to make native ruby IO non-blocking. Sometimes it feels like whack-a-mole, and other times I wonder if I'm really appreciating how complex the edge cases can be, both POSIX, and Ruby wrapped on top.

The more I work on this code, the more I realise how difficult it is to get the right semantics without breaking the code somewhere else.

I really believe that ruby/ruby#1870 is the right solution.

[judofyr]

I haven't had time to look at this because, as you said, there's so many edge cases to take into account. That PR to Ruby looks superinteresting. I hope it gets accepted!

[ioquatix]

@judofyr what I can say, is that an Async::IO::Generic wrapper within an Async::IO::Stream will always work predictably. So, I'd go with that for now. However, I am interested to merge this PR... I just don't know when it will happen.