retry

Easy to use retry decorator.

Features

• No external dependency (stdlib only).
• (Optionally) Preserve function signatures (pip install decorator).
• Original traceback, easy to debug.

Installation

$ pip install retry

API

retry decorator

defretry(exceptions=Exception, tries=-1, delay=0, max_delay=None, backoff=1, jitter=0, logger=logging_logger):
"""Return a retry decorator. :param exceptions: an exception or a tuple of exceptions to catch. default: Exception. :param tries: the maximum number of attempts. default: -1 (infinite). :param delay: initial delay between attempts. default: 0. :param max_delay: the maximum value of delay. default: None (no limit). :param backoff: multiplier applied to delay between attempts. default: 1 (no backoff). :param jitter: extra seconds added to delay between attempts. default: 0. fixed if a number, random if a range tuple (min, max) :param logger: logger.warning(fmt, error, delay) will be called on failed attempts. default: retry.logging_logger. if None, logging is disabled. """

Various retrying logic can be achieved by combination of arguments.

Examples

fromretryimportretry

@retry()defmake_trouble():
'''Retry until succeed'''

@retry(ZeroDivisionError, tries=3, delay=2)defmake_trouble():
'''Retry on ZeroDivisionError, raise error after 3 attempts, sleep 2 seconds between attempts.'''

@retry((ValueError, TypeError), delay=1, backoff=2)defmake_trouble():
'''Retry on ValueError or TypeError, sleep 1, 2, 4, 8, ... seconds between attempts.'''

@retry((ValueError, TypeError), delay=1, backoff=2, max_delay=4)defmake_trouble():
'''Retry on ValueError or TypeError, sleep 1, 2, 4, 4, ... seconds between attempts.'''

@retry(ValueError, delay=1, jitter=1)defmake_trouble():
'''Retry on ValueError, sleep 1, 2, 3, 4, ... seconds between attempts.'''

# If you enable logging, you can get warnings like 'ValueError, retrying in# 1 seconds'if__name__=='__main__':
importlogginglogging.basicConfig()
make_trouble()

retry_call

defretry_call(f, fargs=None, fkwargs=None, exceptions=Exception, tries=-1, delay=0, max_delay=None, backoff=1,
jitter=0,
logger=logging_logger):
""" Calls a function and re-executes it if it failed. :param f: the function to execute. :param fargs: the positional arguments of the function to execute. :param fkwargs: the named arguments of the function to execute. :param exceptions: an exception or a tuple of exceptions to catch. default: Exception. :param tries: the maximum number of attempts. default: -1 (infinite). :param delay: initial delay between attempts. default: 0. :param max_delay: the maximum value of delay. default: None (no limit). :param backoff: multiplier applied to delay between attempts. default: 1 (no backoff). :param jitter: extra seconds added to delay between attempts. default: 0. fixed if a number, random if a range tuple (min, max) :param logger: logger.warning(fmt, error, delay) will be called on failed attempts. default: retry.logging_logger. if None, logging is disabled. :returns: the result of the f function. """

This is very similar to the decorator, except that it takes a function and its arguments as parameters. The use case behind it is to be able to dynamically adjust the retry arguments.

importrequestsfromretry.apiimportretry_calldefmake_trouble(service, info=None):
ifnotinfo:
info=''r=requests.get(service+info)
returnr.textdefwhat_is_my_ip(approach=None):
ifapproach=="optimistic":
tries=1elifapproach=="conservative":
tries=3else:
# skepticaltries=-1result=retry_call(make_trouble, fargs=["http://ipinfo.io/"], fkwargs={"info": "ip"}, tries=tries)
print(result)
what_is_my_ip("conservative")