[WIP] Use a dedicated thread for Zigpy ZNP's serial communication

[dumpfheimer]

I have been playing around with letting zigpy-znp run in a dedicated thread. My experience has been surprisingly pleasing. I feel like lights respond quicker (especially when toggling a bunch of lights simultaneously)

I am quite new to Python and a rudimentary understanding of event loops, but I believe this solution is worth being looked at.

I very much appreciate feedback.

I will take a look at bellows to see if I can learn something from there soon.

[puddly]

Have you taken a look at the bellows' ThreadsafeProxy and EventLoopThread implementations?

• https://github.com/zigpy/bellows/blob/dev/bellows/uart.py#L387-L400
• https://github.com/zigpy/bellows/blob/dev/bellows/thread.py

Managing multiple loops and threads is surprisingly delicate, especially with exceptions, radio probing (which tries/retries connecting multiple times), shutdown, etc. The bellows implementation is not dependent on bellows itself so it should be easy to adapt into ZNP. If it also works, I would like to avoid adding more duplicate code into every single radio library and instead start to move this into zigpy.

[dumpfheimer]

How do you handle the "return to the main thread" in bellows?

[puddly]

How do you handle the "return to the main thread" in bellows?

Everything is done by re-wrapping futures across event loops: https://github.com/zigpy/bellows/blob/3c3ee0296d35eb43d0493eb9b2160bc4484e892c/bellows/thread.py#L106-L107

[dumpfheimer]

Discarded in favor of a bellows approach