python retry decorator

gistfile1.py

import pymongo.errors

# Retry decorator with exponential backoff
def retry(tries=5, delay=0.1, backoff=2):
    """Retries a function or method until it returns True.

    delay sets the initial delay in seconds, and backoff sets the factor by which
    the delay should lengthen after each failure. backoff must be greater than 1,
    or else it isn't really a backoff. tries must be at least 0, and delay
    greater than 0.
    
    Reference:
    http://wiki.python.org/moin/PythonDecoratorLibrary#Retry"""

    if backoff <= 1:
        raise ValueError("backoff must be greater than 1")

    tries = math.floor(tries)
    if tries < 0:
        raise ValueError("tries must be 0 or greater")

    if delay <= 0:
        raise ValueError("delay must be greater than 0")

    def deco_retry(f):
        def f_retry(*args, **kwargs):
            mtries, mdelay = tries, delay # make mutable

            try:
                rv = f(*args, **kwargs) # first attempt
            except pymongo.errors.AutoReconnect:
                logger.exception("Mongo replication set failure")
                rv = False
            while mtries > 0:
                if rv == True: # Done on success
                    return True
                mtries -= 1      # consume an attempt
                time.sleep(mdelay) # wait...
                mdelay *= backoff  # make future wait longer                
                try:
                    rv = f(*args, **kwargs) # Try again
                except pymongo.errors.AutoReconnect:
                    logger.exception("Mongo replication set failure")
                    rv = False
            return False # Ran out of tries :-(

        return f_retry # true decorator -> decorated function
    return deco_retry  # @retry(arg[, ...]) -> true decorator