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import logging
import asyncio
from .. import utils
log = logging.getLogger(__name__)
async def retry(maxRetries, tryFn):
"""
Retry async `tryFn` based on `maxRetries`. Each call to `tryFn` will pass a callable
which should be called with the exception object when an exception can be retried.
Exceptions raised from `tryFn` are treated as fatal.
"""
retry = -1 # we plus first in the loop, and attempt 1 is retry 0
while True:
retry += 1
# if this isn't the first retry then we sleep
if retry > 0:
snooze = float(retry * retry) / 10.0
log.info('Sleeping %0.2f seconds for exponential backoff', snooze)
await asyncio.sleep(utils.calculateSleepTime(retry))
retriableException = None
def retryFor(exc):
nonlocal retriableException
retriableException = exc
res = await tryFn(retryFor)
if not retriableException:
return res
if retry < maxRetries:
log.warning(f'Retrying because of: {retriableException}')
continue
raise retriableException