'Initialize a DNS cache.
@param cleaning_interval: the number of seconds between periodic
cleanings.  The default is 300.0
@type cleaning_interval: float.'

def __init__(self, cleaning_interval=300.0):

    self.data = {}
    self.cleaning_interval = cleaning_interval
    self.next_cleaning = (time.time() + self.cleaning_interval)
    self.lock = _threading.Lock()
