timeout.py

# Copyright (c) 2015 Uber Technologies, Inc.
#
# Permission is hereby granted, free of charge, to any person obtaining a copy
# of this software and associated documentation files (the "Software"), to deal
# in the Software without restriction, including without limitation the rights
# to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
# copies of the Software, and to permit persons to whom the Software is
# furnished to do so, subject to the following conditions:
#
# The above copyright notice and this permission notice shall be included in
# all copies or substantial portions of the Software.
#
# THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
# IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
# FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
# AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
# LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
# OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
# THE SOFTWARE.

from __future__ import absolute_import

import tornado
import tornado.ioloop

import contextlib2

from ..errors import TimeoutError


@contextlib2.contextmanager
def timeout(future, seconds=0, io_loop=None):
    # TODO: This is probably too heavy to attach to every request, should do
    # this in the background.
    io_loop = io_loop or tornado.ioloop.IOLoop.current()

    def raise_timeout(*args, **kwargs):
        if future.running():
            future.set_exception(TimeoutError())
    if not seconds:
        # No timeout if seconds is set to 0.
        yield
    else:
        io_loop.call_later(seconds, raise_timeout)
        yield