throttling.py

import datetime


class Throttle(object):

    def __init__(self, domain, max_hits, period):
        self.domain = domain
        self.max_hits = max_hits
        self.hits = 0
        self.period = datetime.timedelta(seconds=period)
        self.timestamp = datetime.datetime.min

    def throttle(self, last_response):
        delta = ((self.timestamp + self.period) - last_response).total_seconds()
        if delta > 0:
            if self.hits < self.max_hits:
                self.hits += 1
                return delta / (self.max_hits - self.hits)
            else:
                return delta
        else:
            self.timestamp = last_response
            self.hits = 1
            return 0