80 lines
2.5 KiB
Python
80 lines
2.5 KiB
Python
# Copyright 2015 Tesora Inc.
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# All Rights Reserved.
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#
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# Licensed under the Apache License, Version 2.0 (the "License"); you may
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# not use this file except in compliance with the License. You may obtain
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# a copy of the License at
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#
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# http://www.apache.org/licenses/LICENSE-2.0
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#
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# Unless required by applicable law or agreed to in writing, software
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# distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
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# WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
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# License for the specific language governing permissions and limitations
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# under the License.
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import logging
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import traceback
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class DefaultRootHandler(logging.StreamHandler):
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"""A singleton StreamHandler"""
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__handler = logging.StreamHandler()
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__singleton = None
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__info = None
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__enable_backtrace = False
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@classmethod
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def activate(cls, enable_backtrace=False):
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# leverage the singleton __handler which has an
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# acquire() method to create a critical section.
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cls.__handler.acquire()
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if cls.__singleton is None:
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cls.__singleton = DefaultRootHandler()
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cls.__enable_backtrace = enable_backtrace
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cls.__handler.release()
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return cls.__singleton
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@classmethod
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def set_info(cls, info=None):
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cls.__info = info
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def __init__(self):
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if DefaultRootHandler.__singleton is not None:
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raise Exception(
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"Do not directly instantiate DefaultRootHandler(). "
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"Only use the activate() class method.")
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super(DefaultRootHandler, self).__init__()
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def emit(self, record):
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if DefaultRootHandler.__info:
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msg = ("*************************\n" +
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"Unhandled message logged from " +
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DefaultRootHandler.__info + ", " +
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record.name + "\n")
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if DefaultRootHandler.__enable_backtrace:
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msg += ''.join(traceback.format_stack()) + "\n"
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msg += "*************************\n"
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self.stream.write(msg)
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self.flush()
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class DefaultRootLogger(object):
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"""A root logger that uses the singleton handler"""
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def __init__(self, enable_backtrace=False):
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super(DefaultRootLogger, self).__init__()
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handler = DefaultRootHandler.activate(
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enable_backtrace=enable_backtrace
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)
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handler.acquire()
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if handler not in logging.getLogger('').handlers:
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logging.getLogger('').addHandler(handler)
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handler.release()
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