[Python-ideas] Async API
yselivanov.ml at gmail.com
Thu Oct 25 01:37:57 CEST 2012
On 2012-10-24, at 7:25 PM, Steve Dower <Steve.Dower at microsoft.com> wrote:
> Could another workaround be to spawn the cleanup code without yielding - in effect saying "go and do this, but don't come back"? Then there is nowhere for the scheduler to throw the exception.
> I ask because this falls out naturally with my implementation (code is coming, but work is taking priority right now): "do_cleanup()" instead of "yield do_cleanup()". I haven't tried it in this context yet, so no idea whether it works, but I don't see why it wouldn't. In a system without the @async decorator you'd need a "scheduler.current.spawn(do_cleanup)" instead of yield [from]s, but it can still be done.
Well, yes, this will work.
If we have the following:
# "async()" is a way to launch coroutines in my framework without
# "coming back"; with it they just return a promise/future that needs
# to be yielded again
The solution is very limited though. Imagine if you have lots of cleanup code
yield c1.close().async() # go and do this, but don't come back
The above won't work, as scheduler would have an opportunity to break
everything on the second 'yield'.
You may solve it by grouping cleanup code in a separate inner coroutine,
yield cleanup().async() # go and do this, but don't come back
But that looks even worse than using 'with protect_finally()'.
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