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William Kurkian6f436d02019-02-06 16:25:01 -05001# Copyright 2017-present Open Networking Foundation
2#
3# Licensed under the Apache License, Version 2.0 (the "License");
4# you may not use this file except in compliance with the License.
5# You may obtain a copy of the License at
6#
7# http://www.apache.org/licenses/LICENSE-2.0
8#
9# Unless required by applicable law or agreed to in writing, software
10# distributed under the License is distributed on an "AS IS" BASIS,
11# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
12# See the License for the specific language governing permissions and
13# limitations under the License.
14from twisted.internet import reactor
15from twisted.internet.defer import Deferred
16from twisted.internet.error import AlreadyCalled
17
18
19class TimeOutError(Exception): pass
20
21
22class DeferredWithTimeout(Deferred):
23 """
24 Deferred with a timeout. If neither the callback nor the errback method
25 is not called within the given time, the deferred's errback will be called
26 with a TimeOutError() exception.
27
28 All other uses are the same as of Deferred().
29 """
30 def __init__(self, timeout=1.0):
31 Deferred.__init__(self)
32 self._timeout = timeout
33 self.timer = reactor.callLater(timeout, self.timed_out)
34
35 def timed_out(self):
36 self.errback(
37 TimeOutError('timed out after {} seconds'.format(self._timeout)))
38
39 def callback(self, result):
40 self._cancel_timer()
41 return Deferred.callback(self, result)
42
43 def errback(self, fail):
44 self._cancel_timer()
45 return Deferred.errback(self, fail)
46
47 def cancel(self):
48 self._cancel_timer()
49 return Deferred.cancel(self)
50
51 def _cancel_timer(self):
52 try:
53 self.timer.cancel()
54 except AlreadyCalled:
55 pass
56