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
|
# Copyright 2015 Tesora Inc.
# All Rights Reserved.
#
# 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
import traceback
class DefaultRootHandler(logging.StreamHandler):
"""A singleton StreamHandler"""
__handler = logging.StreamHandler()
__singleton = None
__info = None
__enable_backtrace = False
@classmethod
def activate(cls, enable_backtrace=False):
# leverage the singleton __handler which has an
# acquire() method to create a critical section.
cls.__handler.acquire()
if cls.__singleton is None:
cls.__singleton = DefaultRootHandler()
cls.__enable_backtrace = enable_backtrace
cls.__handler.release()
return cls.__singleton
@classmethod
def set_info(cls, info=None):
cls.__info = info
def __init__(self):
if DefaultRootHandler.__singleton is not None:
raise Exception(
"Do not directly instantiate DefaultRootHandler(). "
"Only use the activate() class method.")
super(DefaultRootHandler, self).__init__()
def emit(self, record):
if DefaultRootHandler.__info:
msg = ("*************************\n" +
"Unhandled message logged from " +
DefaultRootHandler.__info + ", " +
record.name + "\n")
if DefaultRootHandler.__enable_backtrace:
msg += ''.join(traceback.format_stack()) + "\n"
msg += "*************************\n"
self.stream.write(msg)
self.flush()
class DefaultRootLogger(object):
"""A root logger that uses the singleton handler"""
def __init__(self, enable_backtrace=False):
super(DefaultRootLogger, self).__init__()
handler = DefaultRootHandler.activate(
enable_backtrace=enable_backtrace
)
handler.acquire()
if handler not in logging.getLogger('').handlers:
logging.getLogger('').addHandler(handler)
handler.release()
|
