Remove UART thread

[puddly]

Zigpy uses pyserial-asyncio-fast if it is installed. This fork of pyserial-asyncio fixes a bug where writes are buffered unnecessarily, essentially introducing unnecessary delays to serial writes (@pipiche38 you may want to add this as a dependency to benefit from it).

The purpose of the UART thread was to allow bellows to instantly respond to packets with an ACK and avoid timing problems caused by a busy main asyncio event loop. This problem is fixed by pyserial-asyncio-fast, as protocol.data_received synchronously parses any incoming data and immediately calls transport.write, without invoking the event loop at all.

In my local tests, 4608/4608 transport.write calls immediately resulted in a successful write syscall, meaning the protocol's write buffer was never filled at all.

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Comparison is base (e4c624a) 99.81% compared to head (a390415) 99.78%.

Additional details and impacted files

@@            Coverage Diff             @@
##              dev     #598      +/-   ##
==========================================
- Coverage   99.81%   99.78%   -0.03%     
==========================================
  Files          68       67       -1     
  Lines        4808     4719      -89     
==========================================
- Hits         4799     4709      -90     
- Misses          9       10       +1     

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[pipiche38]

@puddly thanks for the ping. I had a look to the PR and you never refer to the pyserial-asyncio-fast. At what level is pyserial-asyncio-fast replacing pyserial-asyncio ?

[puddly]

@pipiche38 Zigpy does it automatically if the package is available: https://github.com/zigpy/zigpy/blob/fb19ae5904d79bee43a0188636088499cc674a7b/zigpy/serial.py#L15-L20