from requests_futures.sessions import FuturesSession

import time

class ElapsedFuturesSession(FuturesSession):

    def request(self, method, url, hooks=None, *args, **kwargs):
        start = time.time()
        if hooks is None:
            hooks = {}

        def timing(r, *args, **kwargs):
            r.elapsed = round((time.time() - start) * 1000, 2)

        try:
            if isinstance(hooks['response'], (list, tuple)):
                # needs to be first so we don't time other hooks execution
                hooks['response'].insert(0, timing)
            else:
                hooks['response'] = [timing, hooks['response']]
        except KeyError:
            hooks['response'] = timing

        return super(ElapsedFuturesSession, self) \
            .request(method, url, hooks=hooks, *args, **kwargs)