Sorry for this 3rd email in a row, I'll shut up now.
To clarify, my ideal Timeout context manager would be thus.
async def task(): # let's call this task t1
with Timeout(123):
await asyncio.sleep(321) # let's call this task t2
Given the above, outer task t1 is waiting for task t2, when the timeout
occurs. The context manager should:
1. when entering the block: take a reference for the current task (as it
does now)
2. when the timeout occurs:
a) take a note that the timeout occurred (as it does now)
b) somehow, find out which future our task t1 is waiting for (t2) and
cancel it
3. when exiting the block, if the timeout has occurred:
a) do NOT cancel the task t1
b) raise TimeoutError
This way, normally the outer task gets cancelled anyway simply because of
the exception being raised. However, there is the possibility for the code
to catch the exception and allow the rest of the task to continue executing
as if nothing had happened.
Cheers.
On 28 December 2015 at 10:40, Gustavo Carneiro <[email protected]> wrote:
>
>
> On 28 December 2015 at 06:27, Andrew Svetlov <[email protected]>
> wrote:
>
>> asyncio has wait_for coroutine for timeouts.
>>
>> It works like:
>>
>> async def coro():
>> # do long running task
>> await asyncio.sleep(10000)
>>
>> await asyncio.wait_for(coro(), 1.5)
>>
>> The approach requires splitting code into two functions: one for waiting
>> and other for performing the task.
>>
>> aiohttp has Timeout class (
>> https://github.com/KeepSafe/aiohttp/blob/master/aiohttp/helpers.py#L451-L488
>> ).
>> The code from example may be rewritten as:
>>
>> with Timeout(1.5):
>> # do long running task
>> await asyncio.sleep(10000)
>>
>>
> In my last email I forgot to comment on your original text:
>
>
>> It raises asyncio.TimeoutError and cancels inner code if timeout runs out.
>>
>
> This statement is wrong. It doesn't cancel just the "inner code". If by
> "inner code" you mean the code inside the context manager block, then no,
> it cancels that code and any code that may come after.
>
> --
> Gustavo J. A. M. Carneiro
> Gambit Research
> "The universe is always one step beyond logic." -- Frank Herbert
>
--
Gustavo J. A. M. Carneiro
Gambit Research
"The universe is always one step beyond logic." -- Frank Herbert
