python retries decorator

retriable.py

from time import sleep


class retriable(object):
    """
    A retrying decorator with backoff.

    Use it like so:

        @retriable(tries=60, initial_backoff=60, backoff_multiplier=1)
        def do_something(foo):
             return this_might_explode(foo)

    If side-effectful, you should make sure your decorated function is
    safe to retry ad nauseum!
    """
    def __init__(self, tries=3, initial_backoff=0.5, backoff_multiplier=2):
        """
        :param int tries: how many times to try the function, at most

        :param Union[int, float] initial_backoff: starting sleep in seconds
            between tries

        :param Union[int, float] backoff_multiplier: backoff multiple applied
            after each attempt
        """
        if tries < 1:
            raise ValueError("give us at least one try")
        self._tries = tries
        self._backoff = initial_backoff
        self._multiplier = backoff_multiplier

    def __call__(self, fn, *args, **kwargs):
        def decorator(*args, **kwargs):
            tried = 0
            backoff = self._backoff
            while tried < self._tries:
                try:
                    return fn(*args, **kwargs)
                except Exception as e:
                    last_e = e
                    tried += 1
                    log.exception("retriable handled exception")
                    sleep(backoff)
                    backoff *= self._multiplier
            log.error("retries exhausted")
            raise last_e
        return decorator