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
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
|
# 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
import threading
import logging
logger = logging.getLogger(__name__)
class LoggingContext(object):
"""Additional context for log formatting. Contexts are scoped within a
"with" block. Contexts inherit the state of their parent contexts.
Args:
name (str): Name for the context for debugging.
"""
__slots__ = ["parent_context", "name", "__dict__"]
thread_local = threading.local()
class Sentinel(object):
"""Sentinel to represent the root context"""
__slots__ = []
def __str__(self):
return "sentinel"
def copy_to(self, record):
pass
sentinel = Sentinel()
def __init__(self, name=None):
self.parent_context = None
self.name = name
def __str__(self):
return "%s@%x" % (self.name, id(self))
@classmethod
def current_context(cls):
"""Get the current logging context from thread local storage"""
return getattr(cls.thread_local, "current_context", cls.sentinel)
def __enter__(self):
"""Enters this logging context into thread local storage"""
if self.parent_context is not None:
raise Exception("Attempt to enter logging context multiple times")
self.parent_context = self.current_context()
self.thread_local.current_context = self
return self
def __exit__(self, type, value, traceback):
"""Restore the logging context in thread local storage to the state it
was before this context was entered.
Returns:
None to avoid suppressing any exeptions that were thrown.
"""
if self.thread_local.current_context is not self:
if self.thread_local.current_context is self.sentinel:
logger.debug("Expected logging context %s has been lost", self)
else:
logger.warn(
"Current logging context %s is not expected context %s",
self.thread_local.current_context,
self
)
self.thread_local.current_context = self.parent_context
self.parent_context = None
def __getattr__(self, name):
"""Delegate member lookup to parent context"""
return getattr(self.parent_context, name)
def copy_to(self, record):
"""Copy fields from this context and its parents to the record"""
if self.parent_context is not None:
self.parent_context.copy_to(record)
for key, value in self.__dict__.items():
setattr(record, key, value)
class LoggingContextFilter(logging.Filter):
"""Logging filter that adds values from the current logging context to each
record.
Args:
**defaults: Default values to avoid formatters complaining about
missing fields
"""
def __init__(self, **defaults):
self.defaults = defaults
def filter(self, record):
"""Add each fields from the logging contexts to the record.
Returns:
True to include the record in the log output.
"""
context = LoggingContext.current_context()
for key, value in self.defaults.items():
setattr(record, key, value)
context.copy_to(record)
return True
class PreserveLoggingContext(object):
"""Captures the current logging context and restores it when the scope is
exited. Used to restore the context after a function using
@defer.inlineCallbacks is resumed by a callback from the reactor."""
__slots__ = ["current_context"]
def __enter__(self):
"""Captures the current logging context"""
self.current_context = LoggingContext.current_context()
LoggingContext.thread_local.current_context = LoggingContext.sentinel
def __exit__(self, type, value, traceback):
"""Restores the current logging context"""
LoggingContext.thread_local.current_context = self.current_context
if self.current_context is not LoggingContext.sentinel:
if self.current_context.parent_context is None:
logger.warn(
"Restoring dead context: %s",
self.current_context,
)
def preserve_context_over_fn(fn, *args, **kwargs):
"""Takes a function and invokes it with the given arguments, but removes
and restores the current logging context while doing so.
If the result is a deferred, call preserve_context_over_deferred before
returning it.
"""
with PreserveLoggingContext():
res = fn(*args, **kwargs)
if isinstance(res, defer.Deferred):
return preserve_context_over_deferred(res)
else:
return res
def preserve_context_over_deferred(deferred):
"""Given a deferred wrap it such that any callbacks added later to it will
be invoked with the current context.
"""
d = defer.Deferred()
current_context = LoggingContext.current_context()
def cb(res):
with PreserveLoggingContext():
LoggingContext.thread_local.current_context = current_context
res = d.callback(res)
return res
def eb(failure):
with PreserveLoggingContext():
LoggingContext.thread_local.current_context = current_context
res = d.errback(failure)
return res
if deferred.called:
return deferred
deferred.addCallbacks(cb, eb)
return d
|
