1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
|
# -*- coding: utf-8 -*-
# Copyright 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 functools import wraps
from synapse.util.logcontext import LoggingContext, PreserveLoggingContext
def debug_deferreds():
"""Cause all deferreds to wait for a reactor tick before running their
callbacks. This increases the chance of getting a stack trace out of
a defer.inlineCallback since the code waiting on the deferred will get
a chance to add an errback before the deferred runs."""
# Helper method for retrieving and restoring the current logging context
# around a callback.
def with_logging_context(fn):
context = LoggingContext.current_context()
def restore_context_callback(x):
with PreserveLoggingContext():
LoggingContext.thread_local.current_context = context
return fn(x)
return restore_context_callback
# We are going to modify the __init__ method of defer.Deferred so we
# need to get a copy of the old method so we can still call it.
old__init__ = defer.Deferred.__init__
# We need to create a deferred to bounce the callbacks through the reactor
# but we don't want to add a callback when we create that deferred so we
# we create a new type of deferred that uses the old __init__ method.
# This is safe as long as the old __init__ method doesn't invoke an
# __init__ using super.
class Bouncer(defer.Deferred):
__init__ = old__init__
# We'll add this as a callback to all Deferreds. Twisted will wait until
# the bouncer deferred resolves before calling the callbacks of the
# original deferred.
def bounce_callback(x):
bouncer = Bouncer()
reactor.callLater(0, with_logging_context(bouncer.callback), x)
return bouncer
# We'll add this as an errback to all Deferreds. Twisted will wait until
# the bouncer deferred resolves before calling the errbacks of the
# original deferred.
def bounce_errback(x):
bouncer = Bouncer()
reactor.callLater(0, with_logging_context(bouncer.errback), x)
return bouncer
@wraps(old__init__)
def new__init__(self, *args, **kargs):
old__init__(self, *args, **kargs)
self.addCallbacks(bounce_callback, bounce_errback)
defer.Deferred.__init__ = new__init__
|
