An easy to use, but functional decorator for retrying on exceptions.
Project description
reretry
An easy to use retry decorator.
This package is a fork from the retry
package, but with some of added community-sourced features.
Features
New features in reretry
:
- Log traceback of an error that lead to a failed attempt.
- Call a custom callback after each failed attempt.
- Can be used with async functions.
From original retry
:
- Retry on specific exceptions.
- Set a maximum number of retries.
- Set a delay between retries.
- Set a maximum delay between retries.
- Set backoff and jitter parameters.
- Use a custom logger.
- No external dependencies (stdlib only).
- (Optionally) Preserve function signatures (
pip install decorator
).
Installation
$ pip install reretry
API
The @retry decorator
Usage
@retry(exceptions=Exception, tries=-1, delay=0, max_delay=None, backoff=1, jitter=0, show_traceback=False, logger=logging_logger, fail_callback=None)
Arguments
-
exceptions
: An exception or a tuple of exceptions to catch. Default: Exception. -
tries
: The maximum number of attempts. default: -1 (infinite). -
delay
: Initial delay between attempts (in seconds). default: 0. -
max_delay
: The maximum value of delay (in seconds). default: None (no limit). -
backoff
: Multiplier applied to delay between attempts. default: 1 (no backoff). -
jitter
: Extra seconds added to delay between attempts. default: 0. Fixed if a number, random if a range tuple (min, max). -
show_traceback
: Print traceback before retrying (Python3 only). default: False. -
logger
:logger.warning(fmt, error, delay)
will be called on failed attempts. default: retry.logging_logger. if None, logging is disabled. -
fail_callback
:fail_callback(e)
will be called after failed attempts.
Examples
from reretry import retry
@retry()
def make_trouble():
'''Retry until succeeds'''
@retry()
async def async_make_trouble():
'''Retry an async function until it succeeds'''
@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.'''
def callback(e: Exception):
'''Print error message'''
print(e)
@retry(ValueError, fail_callback=callback):
def make_trouble():
'''Retry on ValueError, between attempts call callback(e)
(where e is the Exception raised).'''
# If you enable logging, you can get warnings like 'ValueError, retrying in
# 1 seconds'
if __name__ == '__main__':
import logging
logging.basicConfig()
make_trouble()
The retry_call
function
Calls a function and re-executes it if it failed.
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.
Usage
retry_call(f, fargs=None, fkwargs=None, exceptions=Exception, tries=-1, delay=0, max_delay=None, backoff=1, jitter=0, show_traceback=False, logger=logging_logger, fail_callback=None)
Example
import requests
from reretry.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")
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