Created
June 5, 2025 09:49
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Python retry helper
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| import logging | |
| import random | |
| import time | |
| from functools import wraps | |
| logging.basicConfig(level=logging.DEBUG, format='%(message)s') | |
| logger = logging.getLogger() | |
| class RetriesExceededError(Exception): | |
| pass | |
| def retry( | |
| func, | |
| predicate=None, | |
| retries=0, delay=0., | |
| exceptions=(), expected_exceptions=(), | |
| linear_backoff=0., multiplicative_backoff=1., exponential_backoff=1., | |
| ): | |
| @wraps(func) | |
| def wrapper(*args, **kwargs): | |
| d = delay | |
| for i in range(retries + 1): | |
| try: | |
| result = func(*args, **kwargs) | |
| if expected_exceptions != (): | |
| pass # We are waiting for a specific exception | |
| elif predicate is not None and not predicate(result): | |
| logger.debug(f'{func.__name__}() returned bad value') | |
| else: | |
| return result | |
| except expected_exceptions: | |
| return | |
| except exceptions: | |
| logger.debug(f'{func.__name__}() failed, retrying (attempt {i})...', exc_info=True) | |
| logger.info(f'Retrying {func.__name__}() (attempt {i})...') | |
| time.sleep(d) | |
| d = linear_backoff + multiplicative_backoff * delay ** exponential_backoff | |
| raise RetriesExceededError(f'Retrying {func.__name__}() failed ({retries + 1} attempts)') | |
| return wrapper | |
| def f(cutoff): | |
| if random.random() < cutoff: | |
| print('Failure...') | |
| raise ValueError() | |
| print('Success!') | |
| if __name__ == '__main__': | |
| retry(f)(.5) |
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