retry decorator

# 2013-04-08 johnpfeiffer

import time
from functools import wraps


def retry( ExceptionToCheck , tries = 4 , delay = 1 , backoff = 2 , logger = None ):
    """Retry calling the decorated function using an exponential backoff.

    http://www.saltycrane.com/blog/2009/11/trying-out-retry-decorator-python/
    original from: http://wiki.python.org/moin/PythonDecoratorLibrary#Retry

    :param ExceptionToCheck: the exception to check. may be a tuple of
        exceptions to check
    :type ExceptionToCheck: Exception or tuple
    :param tries: number of times to try (not retry) before giving up
    :type tries: int
    :param delay: initial delay between retries in seconds
    :type delay: int
    :param backoff: backoff multiplier e.g. value of 2 will double the delay
        each retry
    :type backoff: int
    :param logger: logger to use. If None, print
    :type logger: logging.Logger instance
    """
    def deco_retry( f ):

        @wraps( f )
        def f_retry( *args , **kwargs ):
            mtries, mdelay = tries, delay
            while mtries > 1:
                try:
                    return f( *args , **kwargs )
                except ExceptionToCheck, e:
                    message = u"{}, Retrying in {} seconds...".format( str(e) , mdelay )
                    if logger:
                        logger.warning( message )
                    print message
                    time.sleep( mdelay )
                    mtries -= 1
                    mdelay *= backoff
            return f( *args , **kwargs )

        return f_retry  # true decorator

    return deco_retry