Client streaming

[nat-n]

Picks up where #45 left off. @hozn

• Adds full support for stream_unary and stream_stream method types in the generated grpclib based client
• support independent timing of messages on upload/download streams as demonstrated in the test with the help of an AsyncChannel
• Also did some work on the generate script, initially just cos tests were failing due to the lack of special handling in case there's a pycache in the inputs, but I might have gotten carried away.
• Also did a bit of general cleanup of type annotations guided by mypy

[hozn]

@nat-n -- this looks like a great set of changes. That bi-directional streaming implementation is really slick!

[boukeversteegh]

Awesome work! I only found very minor improvements 🥇 👍

If its too much of a hassle to take out the parallelization of generate.py, we could leave it in and I'll see later if I can correct the output. But it would be great if the path whitelisting could still work as before.

[boukeversteegh]

Some things are not working yet. I am making a PR with test-cases :-)

[adriangb]

Hi, just curious why parallelizing the generator script was necessary? It seemed fast enough already (it took like 5 seconds on my laptop). Previously I was just using ptvsd, but that doesn't work now since there can't be multiple debug servers on a single port, so it's now much harder to debug. I think this is the PR where the change was implemented.

[nat-n]

@adament The generator was slow enough to be annoying before. As I recall it this change more than halved the time taken to generate all the test cases though I can't remember the specific times.

What are you trying to debug exactly? the plugin as called by protoc? If you need to be able to run generate with only one concurrent call to protoc then I think it shouldn't be too hard to add an option for that (similar to the -v option). Basically it would just need to switch the two calls to asyncio.gather for a function with the same signature that instead runs the given coroutines in series.

[adriangb]

the generator was slow enough to be annoying before

If it was slow enough to be annoying, then yeah this change is warranted. For me the time it took was totally bearable, but maybe I have a fast CPU 🚤

What are you trying to debug exactly? the plugin as called by protoc?

Yes, precisely.

I think it shouldn't be too hard to add an option for that (similar to the -v option).

Yup that would be nice!