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")