accept loop parameter for Queue

[ali5h]

What do these changes do?

Use case: If one wants to create the Queue in the main thread of the app, but use
it with an async loop that is running in a thread (not the one in the main thread).

Otw. one would have to create the queue in the thread to pick up the correct loop.

Are there changes in behavior for the user?

no change in behavior if used as before. Now user can pass a custom loop.

Checklist

• I think the code is well written
• Add a new news fragment into the CHANGES folder

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This change is 

[codecov]

Codecov Report

Merging #297 (e9b4aee) into master (344ae2f) will not change coverage.
The diff coverage is 100.00%.

@@           Coverage Diff           @@
##           master     #297   +/-   ##
=======================================
  Coverage   95.52%   95.52%           
=======================================
  Files           4        4           
  Lines        1274     1274           
  Branches       84       84           
=======================================
  Hits         1217     1217           
  Misses         50       50           
  Partials        7        7           

Flag	Coverage Δ
unit	95.44% <100.00%> (ø)

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Impacted Files	Coverage Δ
janus/__init__.py	99.68% <100.00%> (ø)

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[asvetlov]

Your request is error-prone, sorry.
The loop should not be transferred between threads, this is the rule of thumb.

[ali5h]

then how do you want to run the queue in its own thread?

[asvetlov]

Create a queue instance in that thread than, that is what I can suggest

[ali5h]

yes, that is exactly the issue, many of python async functions accept loop parameter, what is error prone about this?

[asvetlov]

In asyncio from Python 3.10 only two or three such public functions are left, all others were deprecated the loop argument by 3.8 and removed in 3.10

[ali5h]

the problem is janus is asking for a running loop, which cannot be started yet.

[asvetlov]

The latest janus maybe doesn't fit your (not published) code, sure.
But I'm also sure that the code can be modified to satisfy the latest janus design.
Thus I cannot name it the "problem".

[brianbienvenu]

@ali5h Thanks for this snippet. I setup a new system with old Python 3.7 code & janus 0.4.0 on Python 3.8 & janus 0.6.1, and this was the only change which bit me. Patched the janus init.py with the suggested change and it works fine - good enough for another handful of years.

I'm sure this isn't best practice asyncio use for modern Python, but it's a lot lower friction than upgrading the rest of the codebase.