1 Class 08 — Connection Exception
2 08000 connection_exception
3 08003 connection_does_not_exist
4 08006 connection_failure
5 08001 sqlclient_unable_to_establish_sqlconnection
6 08004 sqlserver_rejected_establishment_of_sqlconnection

# Example is taken from http://aiohttp.readthedocs.io/en/stable/#getting-started
import aiohttp
import asyncioasync def fetch(session, url):
async with session.get(url) as response:
return await response.text()# Client code, provided for reference
async def main():
async with aiohttp.ClientSession() as session:
html = await fetch(session, 'http://python.org')
print(html)loop = asyncio.get_event_loop()
loop.run_until_complete(main())

import aiohttp
@retry(aiohttp.DisconnectedError, aiohttp.ClientError,
aiohttp.HttpProcessingError)
async def fetch(session, url):
async with session.get(url) as response:
return await response.text()

import loggingfrom functools import wrapslog = logging.getLogger(__name__)def retry(*exceptions, retries=3, cooldown=1, verbose=True):"""Decorate an async function to execute it a few times before giving up.Hopes that problem is resolved by another side shortly.Args:exceptions (Tuple[Exception]) : The exceptions expected during function executionretries (int): Number of retries of function execution.cooldown (int): Seconds to wait before retry.verbose (bool): Specifies if we should log about not successful attempts."""def wrap(func):@wraps(func)async def inner(*args, **kwargs):retries_count = 0while True:try:result = await func(*args, **kwargs)except exceptions as err:retries_count += 1message = "Exception during {} execution. " \"{} of {} retries attempted".format(func, retries_count, retries)if retries_count > retries:verbose and log.exception(message)raise RetryExhaustedError(func.__qualname__, args, kwargs) from errelse:verbose and log.warning(message)if cooldown:await asyncio.sleep(cooldown)else:return resultreturn innerreturn wrap