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import time |
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from logging import getLogger |
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from aspectlib import Aspect |
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logger = getLogger(__name__) |
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def retry(func=None, retries=5, backoff=None, exceptions=(IOError, OSError, EOFError), cleanup=None, sleep=time.sleep): |
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""" |
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Decorator that retries the call ``retries`` times if ``func`` raises ``exceptions``. Can use a ``backoff`` function |
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to sleep till next retry. |
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Example:: |
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>>> should_fail = lambda foo=[1,2,3]: foo and foo.pop() |
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>>> @retry |
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... def flaky_func(): |
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... if should_fail(): |
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... raise OSError('Tough luck!') |
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... print("Success!") |
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... |
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>>> flaky_func() |
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Success! |
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If it reaches the retry limit:: |
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>>> @retry |
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... def bad_func(): |
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... raise OSError('Tough luck!') |
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... |
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>>> bad_func() |
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Traceback (most recent call last): |
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... |
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OSError: Tough luck! |
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""" |
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@Aspect(bind=True) |
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def retry_aspect(cutpoint, *args, **kwargs): |
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for count in range(retries + 1): |
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try: |
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if count and cleanup: |
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cleanup(*args, **kwargs) |
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yield |
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break |
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except exceptions as exc: |
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if count == retries: |
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raise |
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if not backoff: |
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timeout = 0 |
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elif isinstance(backoff, (int, float)): |
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timeout = backoff |
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else: |
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timeout = backoff(count) |
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logger.exception("%s(%s, %s) raised exception %s. %s retries left. Sleeping %s secs.", |
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cutpoint.__name__, args, kwargs, exc, retries - count, timeout) |
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sleep(timeout) |
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return retry_aspect if func is None else retry_aspect(func) |
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def exponential_backoff(count): |
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""" |
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Wait 2**N seconds. |
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""" |
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return 2 ** count |
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retry.exponential_backoff = exponential_backoff |
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def straight_backoff(count): |
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""" |
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Wait 1, 2, 5 seconds. All retries after the 3rd retry will wait 5*N-5 seconds. |
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""" |
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return (1, 2, 5)[count] if count < 3 else 5 * count - 5 |
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retry.straight_backoff = straight_backoff |
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def flat_backoff(count): |
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""" |
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Wait 1, 2, 5, 10, 15, 30 and 60 seconds. All retries after the 5th retry will wait 60 seconds. |
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""" |
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return (1, 2, 5, 10, 15, 30, 60)[count if count < 6 else -1] |
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retry.flat_backoff = flat_backoff |
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|
ionelmc /
python-aspectlib
