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agronholm / anyio

High level asynchronous concurrency and networking framework that works on top of either trio or asyncio
MIT License
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wait queue / ParkingLot support #250

Open belm0 opened 3 years ago

belm0 commented 3 years ago

I'm pondering an anyio implementation of trio-util's AsyncValue, however it's built on Trio ParkingLot.

Is there an asyncio equivalent that could be incorporated into anyio?

smurfix commented 3 years ago

Just use an event.

belm0 commented 3 years ago

I see.

It's a little unfortunate as far as garbage generation. And I notice that Trio doesn't use slots for Event or ParkingLot, so that's two unslotted class instances for every set().

agronholm commented 3 years ago

Even the slimmest possible implementation on asyncio would still instantiate Futures. It might be possible to implement something like a ParkingLot on asyncio but I haven't invested any time on that yet.

belm0 commented 3 years ago

how about:

This will at least make the Trio case efficient, and anyway I think it's good to have an explicit wait queue API rather than require users to be aware of the event idiom.

agronholm commented 3 years ago

The asyncio implementation would involve Futures rather than Event, since Event on asyncio is already built around Futures anyway.

agronholm commented 3 years ago

Having this API would mean a common Event implementation based on this rather than the current one where __new__() instantiates a backend specific subclass.

belm0 commented 3 years ago

And I notice that Trio doesn't use slots for Event or ParkingLot, so that's two unslotted class instances for every set().

trio.Event received some attention and we were able to reduce the number of objects in the implementation by about half.

https://github.com/python-trio/trio/pull/1948

graingert commented 3 years ago

and here's a PR to make ParkingLot slotted: https://github.com/python-trio/trio/pull/1971

belm0 commented 3 years ago

and here's a PR to make ParkingLot slotted: python-trio/trio#1971

This is good change and I overlooked it in my PR. But to clarify: trio.Event() is no longer implemented with ParkingLot.

agronholm commented 3 years ago

It may be possible to implement universal task rescheduling. We'll just copy trio's API and use Futures to implement it on asyncio. The question is, if we ever add Twisted support, will this complicate matters?