byteskeptical / retry

Retry decorator, for the stubborn programmer in all of us

Retry

Exception type based retry decorator for all your problematic functions.

Inspired by: https://wiki.python.org/moin/PythonDecoratorLibrary#Retry

# Parmeters

Exceptions:
    description: Exception(s) to check. May be a tuple of exceptions to check.
    example: IOError or IOError(errno.ECOMM) or (IOError,) or (ValueError, IOError(errno.ECOMM)
    type: Exception type, exception instance, or tuple containing any number of both

Tries:
    description: Number of times to try (not retry) before giving up.
    example: 3
    type: integer

Delay:
    description: Initial delay between retries in seconds.
    example: 3
    type: integer

Backoff:
    description: Backoff multiplier
    example: Value of 2 will double the delay each retry
    type: integer

Silent:
    description: If set then no logging will be attempted.
    example: True
    type: Boolean

Logger:
    description: Logger to use. If None, print.
    example: log = getLogger(__name__)
    type: logging.Logger

Usage

from logging import basicConfig, getLogger, INFO
from retry import retry

basicConfig(level=INFO)
log = getLogger(__name__)

@retry((TestError, IOError), tries=6, delay=1, backoff=2, silent=False, logger=log)
def yourfunction(self, example):
    try:
        ...
    except:
        raise TestError
    finally:
        log.INFO('No Errors!')

Examples

Always Fail

from retry import retry

@retry(Exception, tries=4)
def test_fail(text):
    raise Exception('Fail')

test_fail('It Works!')

Success

from retry import retry

@retry(Exception, tries=4)
def test_success(text):
    print('Success: {0}'.format(text))

test_success('It Works!')

Random Fail

from retry import retry
from random import random

@retry(Exception, tries=4)
def test_random(text):
    x = random()
    if x < 0.5:
        raise Exception('Fail')
    else:
        print('Success: {0}'.format(text))

test_random('It Works!')

Handling Multiple Exceptions

from retry import retry
from random import random

@retry((NameError, IOError), tries=20, delay=1, backoff=1)
def test_multiple_exceptions():
    x = random()
    if x < 0.40:
        raise NameError('NameError')
    elif x < 0.80:
        raise IOError('IOError')
    else:
        raise KeyError('KeyError')

test_multiple_exceptions()