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
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
|
# -*- coding: utf-8 -*-
# Copyright 2014-2016 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.
import logging
from twisted.internet import defer
from synapse.logging.context import make_deferred_yieldable, run_in_background
from synapse.metrics.background_process_metrics import run_as_background_process
logger = logging.getLogger(__name__)
def user_left_room(distributor, user, room_id):
distributor.fire("user_left_room", user=user, room_id=room_id)
# XXX: this is no longer used. We should probably kill it.
def user_joined_room(distributor, user, room_id):
distributor.fire("user_joined_room", user=user, room_id=room_id)
class Distributor(object):
"""A central dispatch point for loosely-connected pieces of code to
register, observe, and fire signals.
Signals are named simply by strings.
TODO(paul): It would be nice to give signals stronger object identities,
so we can attach metadata, docstrings, detect typoes, etc... But this
model will do for today.
"""
def __init__(self):
self.signals = {}
self.pre_registration = {}
def declare(self, name):
if name in self.signals:
raise KeyError("%r already has a signal named %s" % (self, name))
self.signals[name] = Signal(name)
if name in self.pre_registration:
signal = self.signals[name]
for observer in self.pre_registration[name]:
signal.observe(observer)
def observe(self, name, observer):
if name in self.signals:
self.signals[name].observe(observer)
else:
# TODO: Avoid strong ordering dependency by allowing people to
# pre-register observations on signals that don't exist yet.
if name not in self.pre_registration:
self.pre_registration[name] = []
self.pre_registration[name].append(observer)
def fire(self, name, *args, **kwargs):
"""Dispatches the given signal to the registered observers.
Runs the observers as a background process. Does not return a deferred.
"""
if name not in self.signals:
raise KeyError("%r does not have a signal named %s" % (self, name))
run_as_background_process(name, self.signals[name].fire, *args, **kwargs)
class Signal(object):
"""A Signal is a dispatch point that stores a list of callables as
observers of it.
Signals can be "fired", meaning that every callable observing it is
invoked. Firing a signal does not change its state; it can be fired again
at any later point. Firing a signal passes any arguments from the fire
method into all of the observers.
"""
def __init__(self, name):
self.name = name
self.observers = []
def observe(self, observer):
"""Adds a new callable to the observer list which will be invoked by
the 'fire' method.
Each observer callable may return a Deferred."""
self.observers.append(observer)
def fire(self, *args, **kwargs):
"""Invokes every callable in the observer list, passing in the args and
kwargs. Exceptions thrown by observers are logged but ignored. It is
not an error to fire a signal with no observers.
Returns a Deferred that will complete when all the observers have
completed."""
def do(observer):
def eb(failure):
logger.warning(
"%s signal observer %s failed: %r",
self.name,
observer,
failure,
exc_info=(
failure.type,
failure.value,
failure.getTracebackObject(),
),
)
return defer.maybeDeferred(observer, *args, **kwargs).addErrback(eb)
deferreds = [run_in_background(do, o) for o in self.observers]
return make_deferred_yieldable(
defer.gatherResults(deferreds, consumeErrors=True)
)
def __repr__(self):
return "<Signal name=%r>" % (self.name,)
|
