#! /usr/bin/env python
# -*- coding:utf-8 -*-
import time, functools
from random import random
import logging as logging_logger
__all__ = [
'retry'
]
def decorator(caller):
""" Turns caller into a decorator.
Unlike decorator module, function signature is not preserved.
:param caller: caller(f, *args, **kwargs)
"""
def decor(f):
@functools.wraps(f)
def wrapper(*args, **kwargs):
return caller(f, *args, **kwargs)
return wrapper
return decor
def __retry_internal(f, exceptions=Exception, tries=-1, delay=0, max_delay=None, backoff=1, jitter=0,
logger=logging_logger):
"""
Executes a function and retries it if it failed.
:param f: 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.
"""
_tries, _delay = tries, delay
while _tries:
try:
return f()
except exceptions as e:
_tries -= 1
if not _tries:
raise
if logger is not None:
logger.warning('%s, retrying in %s seconds...', e, _delay)
time.sleep(_delay)
_delay *= backoff
if isinstance(jitter, tuple):
_delay += random.uniform(*jitter)
else:
_delay += jitter
if max_delay is not None:
_delay = min(_delay, max_delay)
def retry(exceptions=Exception, tries=-1, delay=0, max_delay=None, backoff=1, jitter=0, logger=logging_logger):
"""Returns 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.
:returns: a retry decorator.
"""
@decorator
def retry_decorator(f, *fargs, **fkwargs):
args = fargs if fargs else list()
kwargs = fkwargs if fkwargs else dict()
return __retry_internal(
functools.partial(f, *args, **kwargs), exceptions, tries, delay, max_delay, backoff, jitter,
logger
)
return retry_decorator
# tries -> 重试几次 delay -> 几秒钟重试一次
@retry(tries=5, delay=3)
def t():
print("-------- in test ----------")
1 / 0
print("aaa")
if __name__ == '__main__':
t()
