[Python-ideas] Async API

[Sam Rushing]

On 10/23/12 4:30 PM, Yury Selivanov wrote:
>
> How do you protect finally statements in shrapnel?  If we have a following 
> coroutine (greenlet style):
>
>    def foo():
>        connection = open_connection()
>        try:
>            spam()
>        finally:
>            [some code]
>            connection.close()
>            
> What happens if you run 'foo.with_timeout(1)' and timeout occurs at 
> "[some code]" point?  Will you just abort 'foo', possibly preventing
> 'connection' from being closed?
>
Timeouts are raised as normal exceptions - for exactly this reason.

The interesting part of the implementation is keeping each
with_timeout() call separate.

If you have nested with_timeout() calls and the outer timeout goes off,
it will skip the inner exception handler and fire only the outer one. 
In other words, the code for with_timeout() verifies that any timeouts
propagating through it belong to it.

https://github.com/ironport/shrapnel/blob/master/coro/_coro.pyx#L1126-1142

-Sam