synapse-product/synapse/util/async.py
Erik Johnston 1c82fbd2eb Implement create_observer.
`create_observer` takes a deferred and create a new deferred that
*observers* the original deferred. Any callbacks added to the observing
deferred will *not* affect the origin deferred.
2015-04-27 13:59:37 +01:00

54 lines
1.4 KiB
Python

# -*- coding: utf-8 -*-
# Copyright 2014, 2015 OpenMarket Ltd
#
# Licensed under the Apache License, Version 2.0 (the "License");
# you may not use this file except in compliance with the License.
# You may obtain a copy of the License at
#
# http://www.apache.org/licenses/LICENSE-2.0
#
# Unless required by applicable law or agreed to in writing, software
# distributed under the License is distributed on an "AS IS" BASIS,
# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
# See the License for the specific language governing permissions and
# limitations under the License.
from twisted.internet import defer, reactor
from .logcontext import PreserveLoggingContext
@defer.inlineCallbacks
def sleep(seconds):
d = defer.Deferred()
reactor.callLater(seconds, d.callback, seconds)
with PreserveLoggingContext():
yield d
def run_on_reactor():
""" This will cause the rest of the function to be invoked upon the next
iteration of the main loop
"""
return sleep(0)
def create_observer(deferred):
"""Creates a deferred that observes the result or failure of the given
deferred *without* affecting the given deferred.
"""
d = defer.Deferred()
def callback(r):
d.callback(r)
return r
def errback(f):
d.errback(f)
return f
deferred.addCallbacks(callback, errback)
return d