Easy to use retry decorator.
[This is a fork of https://github.com/invl/retry which is not maintained anymore]
- No external dependency (stdlib only).
- (Optionally) Preserve function signatures (pip install decorator).
- Original traceback, easy to debug.
$ pip install retry2def retry(exceptions=Exception, tries=-1, delay=0, max_delay=None, backoff=1, jitter=0, logger=logging_logger,
on_exception=None):
"""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.
:param on_exception: handler called when exception occurs. will be passed the captured
exception as an argument. further retries are stopped when handler
returns True. default: None
"""Various retrying logic can be achieved by combination of arguments.
from retry import retry@retry()
def make_trouble():
'''Retry until succeed'''@retry(ZeroDivisionError, tries=3, delay=2)
def make_trouble():
'''Retry on ZeroDivisionError, raise error after 3 attempts, sleep 2 seconds between attempts.'''@retry((ValueError, TypeError), delay=1, backoff=2)
def make_trouble():
'''Retry on ValueError or TypeError, sleep 1, 2, 4, 8, ... seconds between attempts.'''@retry((ValueError, TypeError), delay=1, backoff=2, max_delay=4)
def make_trouble():
'''Retry on ValueError or TypeError, sleep 1, 2, 4, 4, ... seconds between attempts.'''@retry(ValueError, delay=1, jitter=1)
def make_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__':
import logging
logging.basicConfig()
make_trouble()def retry_call(f, fargs=None, fkwargs=None, exceptions=Exception, tries=-1, delay=0, max_delay=None, backoff=1,
jitter=0, logger=logging_logger, on_exception=None):
"""
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.
:param on_exception: handler called when exception occurs. will be passed the captured
exception as an argument. further retries are stopped when handler
returns True. default: None
: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.
import requests
from retry.api import retry_call
def make_trouble(service, info=None):
if not info:
info = ''
r = requests.get(service + info)
return r.text
def what_is_my_ip(approach=None):
if approach == "optimistic":
tries = 1
elif approach == "conservative":
tries = 3
else:
# skeptical
tries = -1
result = retry_call(make_trouble, fargs=["http://ipinfo.io/"], fkwargs={"info": "ip"}, tries=tries)
print(result)
what_is_my_ip("conservative")