132 lines
4.5 KiB
Python
132 lines
4.5 KiB
Python
# 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.
|
|
|
|
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
|