Gerasimov Mikhail Gerasimov Mikhail - 6 months ago 9
Python Question

Is there any way to find which one of multiple timers raised exception?

import asyncio
from aiohttp import Timeout


async def main():
try:
with Timeout(1) as t1:
with Timeout(1) as t2:
await asyncio.sleep(2)
except asyncio.TimeoutError as exc:

# Which one of timers raised this `exc`?
# Something like:

# get_caller(exc) is t1 -> False
# get_caller(exc) is t2 -> True

pass


if __name__ == '__main__':
loop = asyncio.get_event_loop()
loop.run_until_complete(main())


Since both timers have same timeout, both of them can raise
TimeoutError
. I want to know which one did it. Is it possible?

Answer
async def main_async():
    try:
        with NamedTimeout('outer', 0.5) as t1:
            with NamedTimeout('inner', 0.3) as t2:
                await asyncio.sleep(2)
    except asyncio.TimeoutError as e:
        print(e.timeout_name)

class NamedTimeout(Timeout):
    def __init__(self, name, timeout, *, loop=None):
        super().__init__(timeout, loop=loop)
        self.name = name

    def __exit__(self, exc_type, exc_val, exc_tb):
        try:
            super().__exit__(exc_type, exc_val, exc_tb)
        except asyncio.TimeoutError as e:
            e.timeout_name = self.name
            raise

If you vary the timeout values you will see it always prints out the name of the shorter timeout.