625 lines
18 KiB
Python
625 lines
18 KiB
Python
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# -*- test-case-name: twisted.test.test_log -*-
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# Copyright (c) Twisted Matrix Laboratories.
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# See LICENSE for details.
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"""
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Logging and metrics infrastructure.
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"""
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from __future__ import division, absolute_import
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import sys
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import time
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import warnings
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from datetime import datetime
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import logging
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from zope.interface import Interface
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from twisted.python.compat import unicode, _PY3
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from twisted.python import context
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from twisted.python import reflect
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from twisted.python import util
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from twisted.python import failure
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from twisted.python.threadable import synchronize
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class ILogContext:
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"""
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Actually, this interface is just a synonym for the dictionary interface,
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but it serves as a key for the default information in a log.
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I do not inherit from C{Interface} because the world is a cruel place.
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"""
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class ILogObserver(Interface):
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"""
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An observer which can do something with log events.
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Given that most log observers are actually bound methods, it's okay to not
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explicitly declare provision of this interface.
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"""
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def __call__(eventDict):
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"""
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Log an event.
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@type eventDict: C{dict} with C{str} keys.
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@param eventDict: A dictionary with arbitrary keys. However, these
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keys are often available:
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- C{message}: A C{tuple} of C{str} containing messages to be
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logged.
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- C{system}: A C{str} which indicates the "system" which is
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generating this event.
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- C{isError}: A C{bool} indicating whether this event represents
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an error.
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- C{failure}: A L{failure.Failure} instance
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- C{why}: Used as header of the traceback in case of errors.
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- C{format}: A string format used in place of C{message} to
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customize the event. The intent is for the observer to format
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a message by doing something like C{format % eventDict}.
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"""
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context.setDefault(ILogContext,
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{"isError": 0,
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"system": "-"})
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def callWithContext(ctx, func, *args, **kw):
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newCtx = context.get(ILogContext).copy()
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newCtx.update(ctx)
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return context.call({ILogContext: newCtx}, func, *args, **kw)
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def callWithLogger(logger, func, *args, **kw):
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"""
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Utility method which wraps a function in a try:/except:, logs a failure if
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one occurrs, and uses the system's logPrefix.
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"""
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try:
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lp = logger.logPrefix()
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except KeyboardInterrupt:
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raise
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except:
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lp = '(buggy logPrefix method)'
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err(system=lp)
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try:
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return callWithContext({"system": lp}, func, *args, **kw)
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except KeyboardInterrupt:
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raise
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except:
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err(system=lp)
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def err(_stuff=None, _why=None, **kw):
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"""
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Write a failure to the log.
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The C{_stuff} and C{_why} parameters use an underscore prefix to lessen
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the chance of colliding with a keyword argument the application wishes
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to pass. It is intended that they be supplied with arguments passed
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positionally, not by keyword.
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@param _stuff: The failure to log. If C{_stuff} is C{None} a new
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L{Failure} will be created from the current exception state. If
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C{_stuff} is an C{Exception} instance it will be wrapped in a
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L{Failure}.
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@type _stuff: C{NoneType}, C{Exception}, or L{Failure}.
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@param _why: The source of this failure. This will be logged along with
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C{_stuff} and should describe the context in which the failure
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occurred.
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@type _why: C{str}
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"""
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if _stuff is None:
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_stuff = failure.Failure()
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if isinstance(_stuff, failure.Failure):
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msg(failure=_stuff, why=_why, isError=1, **kw)
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elif isinstance(_stuff, Exception):
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msg(failure=failure.Failure(_stuff), why=_why, isError=1, **kw)
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else:
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msg(repr(_stuff), why=_why, isError=1, **kw)
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deferr = err
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class Logger:
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"""
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This represents a class which may 'own' a log. Used by subclassing.
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"""
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def logPrefix(self):
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"""
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Override this method to insert custom logging behavior. Its
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return value will be inserted in front of every line. It may
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be called more times than the number of output lines.
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"""
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return '-'
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class LogPublisher:
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"""
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Class for singleton log message publishing.
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"""
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synchronized = ['msg']
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def __init__(self):
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self.observers = []
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def addObserver(self, other):
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"""
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Add a new observer.
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@type other: Provider of L{ILogObserver}
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@param other: A callable object that will be called with each new log
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message (a dict).
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"""
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assert callable(other)
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self.observers.append(other)
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def removeObserver(self, other):
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"""
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Remove an observer.
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"""
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self.observers.remove(other)
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def msg(self, *message, **kw):
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"""
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Log a new message.
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The message should be a native string, i.e. bytes on Python 2 and
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Unicode on Python 3. For compatibility with both use the native string
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syntax, for example::
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>>> log.msg('Hello, world.')
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You MUST avoid passing in Unicode on Python 2, and the form::
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>>> log.msg('Hello ', 'world.')
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This form only works (sometimes) by accident.
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Keyword arguments will be converted into items in the event
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dict that is passed to L{ILogObserver} implementations.
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Each implementation, in turn, can define keys that are used
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by it specifically, in addition to common keys listed at
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L{ILogObserver.__call__}.
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For example, to set the C{system} parameter while logging
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a message::
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>>> log.msg('Started', system='Foo')
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"""
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actualEventDict = (context.get(ILogContext) or {}).copy()
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actualEventDict.update(kw)
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actualEventDict['message'] = message
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actualEventDict['time'] = time.time()
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for i in range(len(self.observers) - 1, -1, -1):
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try:
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self.observers[i](actualEventDict)
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except KeyboardInterrupt:
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# Don't swallow keyboard interrupt!
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raise
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except UnicodeEncodeError:
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raise
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except:
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observer = self.observers[i]
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self.observers[i] = lambda event: None
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try:
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self._err(failure.Failure(),
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"Log observer %s failed." % (observer,))
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except:
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# Sometimes err() will throw an exception,
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# e.g. RuntimeError due to blowing the stack; if that
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# happens, there's not much we can do...
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pass
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self.observers[i] = observer
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def _err(self, failure, why):
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"""
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Log a failure.
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Similar in functionality to the global {err} function, but the failure
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gets published only to observers attached to this publisher.
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@param failure: The failure to log.
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@type failure: L{Failure}.
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@param why: The source of this failure. This will be logged along with
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the C{failure} and should describe the context in which the failure
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occurred.
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@type why: C{str}
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"""
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self.msg(failure=failure, why=why, isError=1)
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def showwarning(self, message, category, filename, lineno, file=None,
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line=None):
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"""
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Twisted-enabled wrapper around L{warnings.showwarning}.
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If C{file} is C{None}, the default behaviour is to emit the warning to
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the log system, otherwise the original L{warnings.showwarning} Python
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function is called.
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"""
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if file is None:
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self.msg(warning=message, category=reflect.qual(category),
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filename=filename, lineno=lineno,
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format="%(filename)s:%(lineno)s: %(category)s: %(warning)s")
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else:
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if sys.version_info < (2, 6):
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_oldshowwarning(message, category, filename, lineno, file)
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else:
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_oldshowwarning(message, category, filename, lineno, file, line)
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synchronize(LogPublisher)
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try:
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theLogPublisher
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except NameError:
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theLogPublisher = LogPublisher()
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addObserver = theLogPublisher.addObserver
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removeObserver = theLogPublisher.removeObserver
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msg = theLogPublisher.msg
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showwarning = theLogPublisher.showwarning
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def _safeFormat(fmtString, fmtDict):
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"""
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Try to format the string C{fmtString} using C{fmtDict} arguments,
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swallowing all errors to always return a string.
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"""
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# There's a way we could make this if not safer at least more
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# informative: perhaps some sort of str/repr wrapper objects
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# could be wrapped around the things inside of C{fmtDict}. That way
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# if the event dict contains an object with a bad __repr__, we
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# can only cry about that individual object instead of the
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# entire event dict.
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try:
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text = fmtString % fmtDict
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except KeyboardInterrupt:
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raise
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except:
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try:
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text = ('Invalid format string or unformattable object in log message: %r, %s' % (fmtString, fmtDict))
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except:
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try:
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text = 'UNFORMATTABLE OBJECT WRITTEN TO LOG with fmt %r, MESSAGE LOST' % (fmtString,)
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except:
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text = 'PATHOLOGICAL ERROR IN BOTH FORMAT STRING AND MESSAGE DETAILS, MESSAGE LOST'
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return text
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def textFromEventDict(eventDict):
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"""
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Extract text from an event dict passed to a log observer. If it cannot
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handle the dict, it returns None.
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The possible keys of eventDict are:
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- C{message}: by default, it holds the final text. It's required, but can
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be empty if either C{isError} or C{format} is provided (the first
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having the priority).
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- C{isError}: boolean indicating the nature of the event.
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- C{failure}: L{failure.Failure} instance, required if the event is an
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error.
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- C{why}: if defined, used as header of the traceback in case of errors.
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- C{format}: string format used in place of C{message} to customize
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the event. It uses all keys present in C{eventDict} to format
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the text.
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Other keys will be used when applying the C{format}, or ignored.
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"""
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edm = eventDict['message']
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if not edm:
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if eventDict['isError'] and 'failure' in eventDict:
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text = ((eventDict.get('why') or 'Unhandled Error')
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+ '\n' + eventDict['failure'].getTraceback())
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elif 'format' in eventDict:
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text = _safeFormat(eventDict['format'], eventDict)
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else:
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# we don't know how to log this
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return
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else:
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text = ' '.join(map(reflect.safe_str, edm))
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return text
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class FileLogObserver:
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"""
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Log observer that writes to a file-like object.
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@type timeFormat: C{str} or C{NoneType}
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@ivar timeFormat: If not C{None}, the format string passed to strftime().
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"""
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timeFormat = None
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def __init__(self, f):
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self.write = f.write
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self.flush = f.flush
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def getTimezoneOffset(self, when):
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"""
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Return the current local timezone offset from UTC.
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@type when: C{int}
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@param when: POSIX (ie, UTC) timestamp for which to find the offset.
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@rtype: C{int}
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@return: The number of seconds offset from UTC. West is positive,
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east is negative.
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"""
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offset = datetime.utcfromtimestamp(when) - datetime.fromtimestamp(when)
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return offset.days * (60 * 60 * 24) + offset.seconds
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def formatTime(self, when):
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"""
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Format the given UTC value as a string representing that time in the
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local timezone.
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By default it's formatted as a ISO8601-like string (ISO8601 date and
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ISO8601 time separated by a space). It can be customized using the
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C{timeFormat} attribute, which will be used as input for the underlying
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L{datetime.datetime.strftime} call.
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@type when: C{int}
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@param when: POSIX (ie, UTC) timestamp for which to find the offset.
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@rtype: C{str}
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"""
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if self.timeFormat is not None:
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return datetime.fromtimestamp(when).strftime(self.timeFormat)
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tzOffset = -self.getTimezoneOffset(when)
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when = datetime.utcfromtimestamp(when + tzOffset)
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tzHour = abs(int(tzOffset / 60 / 60))
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tzMin = abs(int(tzOffset / 60 % 60))
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if tzOffset < 0:
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tzSign = '-'
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else:
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tzSign = '+'
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return '%d-%02d-%02d %02d:%02d:%02d%s%02d%02d' % (
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when.year, when.month, when.day,
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when.hour, when.minute, when.second,
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tzSign, tzHour, tzMin)
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def emit(self, eventDict):
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text = textFromEventDict(eventDict)
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if text is None:
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return
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timeStr = self.formatTime(eventDict['time'])
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fmtDict = {'system': eventDict['system'], 'text': text.replace("\n", "\n\t")}
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msgStr = _safeFormat("[%(system)s] %(text)s\n", fmtDict)
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util.untilConcludes(self.write, timeStr + " " + msgStr)
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util.untilConcludes(self.flush) # Hoorj!
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def start(self):
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"""
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Start observing log events.
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"""
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addObserver(self.emit)
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def stop(self):
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"""
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Stop observing log events.
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"""
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removeObserver(self.emit)
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class PythonLoggingObserver(object):
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"""
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Output twisted messages to Python standard library L{logging} module.
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WARNING: specific logging configurations (example: network) can lead to
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a blocking system. Nothing is done here to prevent that, so be sure to not
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use this: code within Twisted, such as twisted.web, assumes that logging
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does not block.
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"""
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def __init__(self, loggerName="twisted"):
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"""
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@param loggerName: identifier used for getting logger.
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@type loggerName: C{str}
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"""
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self.logger = logging.getLogger(loggerName)
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def emit(self, eventDict):
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"""
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Receive a twisted log entry, format it and bridge it to python.
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By default the logging level used is info; log.err produces error
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level, and you can customize the level by using the C{logLevel} key::
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>>> log.msg('debugging', logLevel=logging.DEBUG)
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"""
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if 'logLevel' in eventDict:
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level = eventDict['logLevel']
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elif eventDict['isError']:
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level = logging.ERROR
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else:
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level = logging.INFO
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text = textFromEventDict(eventDict)
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if text is None:
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return
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self.logger.log(level, text)
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def start(self):
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"""
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Start observing log events.
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"""
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addObserver(self.emit)
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def stop(self):
|
||
|
"""
|
||
|
Stop observing log events.
|
||
|
"""
|
||
|
removeObserver(self.emit)
|
||
|
|
||
|
|
||
|
class StdioOnnaStick:
|
||
|
"""
|
||
|
Class that pretends to be stdout/err, and turns writes into log messages.
|
||
|
|
||
|
@ivar isError: boolean indicating whether this is stderr, in which cases
|
||
|
log messages will be logged as errors.
|
||
|
|
||
|
@ivar encoding: unicode encoding used to encode any unicode strings
|
||
|
written to this object.
|
||
|
"""
|
||
|
|
||
|
closed = 0
|
||
|
softspace = 0
|
||
|
mode = 'wb'
|
||
|
name = '<stdio (log)>'
|
||
|
|
||
|
def __init__(self, isError=0, encoding=None):
|
||
|
self.isError = isError
|
||
|
if encoding is None:
|
||
|
encoding = sys.getdefaultencoding()
|
||
|
self.encoding = encoding
|
||
|
self.buf = ''
|
||
|
|
||
|
def close(self):
|
||
|
pass
|
||
|
|
||
|
def fileno(self):
|
||
|
return -1
|
||
|
|
||
|
def flush(self):
|
||
|
pass
|
||
|
|
||
|
def read(self):
|
||
|
raise IOError("can't read from the log!")
|
||
|
|
||
|
readline = read
|
||
|
readlines = read
|
||
|
seek = read
|
||
|
tell = read
|
||
|
|
||
|
def write(self, data):
|
||
|
if not _PY3 and isinstance(data, unicode):
|
||
|
data = data.encode(self.encoding)
|
||
|
d = (self.buf + data).split('\n')
|
||
|
self.buf = d[-1]
|
||
|
messages = d[0:-1]
|
||
|
for message in messages:
|
||
|
msg(message, printed=1, isError=self.isError)
|
||
|
|
||
|
def writelines(self, lines):
|
||
|
for line in lines:
|
||
|
if not _PY3 and isinstance(line, unicode):
|
||
|
line = line.encode(self.encoding)
|
||
|
msg(line, printed=1, isError=self.isError)
|
||
|
|
||
|
|
||
|
try:
|
||
|
_oldshowwarning
|
||
|
except NameError:
|
||
|
_oldshowwarning = None
|
||
|
|
||
|
|
||
|
def startLogging(file, *a, **kw):
|
||
|
"""
|
||
|
Initialize logging to a specified file.
|
||
|
|
||
|
@return: A L{FileLogObserver} if a new observer is added, None otherwise.
|
||
|
"""
|
||
|
if isinstance(file, StdioOnnaStick):
|
||
|
return
|
||
|
flo = FileLogObserver(file)
|
||
|
startLoggingWithObserver(flo.emit, *a, **kw)
|
||
|
return flo
|
||
|
|
||
|
|
||
|
|
||
|
def startLoggingWithObserver(observer, setStdout=1):
|
||
|
"""
|
||
|
Initialize logging to a specified observer. If setStdout is true
|
||
|
(defaults to yes), also redirect sys.stdout and sys.stderr
|
||
|
to the specified file.
|
||
|
"""
|
||
|
global defaultObserver, _oldshowwarning
|
||
|
if not _oldshowwarning:
|
||
|
_oldshowwarning = warnings.showwarning
|
||
|
warnings.showwarning = showwarning
|
||
|
if defaultObserver:
|
||
|
defaultObserver.stop()
|
||
|
defaultObserver = None
|
||
|
addObserver(observer)
|
||
|
msg("Log opened.")
|
||
|
if setStdout:
|
||
|
sys.stdout = logfile
|
||
|
sys.stderr = logerr
|
||
|
|
||
|
|
||
|
class NullFile:
|
||
|
softspace = 0
|
||
|
def read(self): pass
|
||
|
def write(self, bytes): pass
|
||
|
def flush(self): pass
|
||
|
def close(self): pass
|
||
|
|
||
|
|
||
|
def discardLogs():
|
||
|
"""
|
||
|
Throw away all logs.
|
||
|
"""
|
||
|
global logfile
|
||
|
logfile = NullFile()
|
||
|
|
||
|
|
||
|
# Prevent logfile from being erased on reload. This only works in cpython.
|
||
|
try:
|
||
|
logfile
|
||
|
except NameError:
|
||
|
logfile = StdioOnnaStick(0, getattr(sys.stdout, "encoding", None))
|
||
|
logerr = StdioOnnaStick(1, getattr(sys.stderr, "encoding", None))
|
||
|
|
||
|
|
||
|
|
||
|
class DefaultObserver:
|
||
|
"""
|
||
|
Default observer.
|
||
|
|
||
|
Will ignore all non-error messages and send error messages to sys.stderr.
|
||
|
Will be removed when startLogging() is called for the first time.
|
||
|
"""
|
||
|
stderr = sys.stderr
|
||
|
|
||
|
def _emit(self, eventDict):
|
||
|
if eventDict["isError"]:
|
||
|
if 'failure' in eventDict:
|
||
|
text = ((eventDict.get('why') or 'Unhandled Error')
|
||
|
+ '\n' + eventDict['failure'].getTraceback())
|
||
|
else:
|
||
|
text = " ".join([str(m) for m in eventDict["message"]]) + "\n"
|
||
|
|
||
|
self.stderr.write(text)
|
||
|
self.stderr.flush()
|
||
|
|
||
|
def start(self):
|
||
|
addObserver(self._emit)
|
||
|
|
||
|
def stop(self):
|
||
|
removeObserver(self._emit)
|
||
|
|
||
|
|
||
|
|
||
|
try:
|
||
|
defaultObserver
|
||
|
except NameError:
|
||
|
defaultObserver = DefaultObserver()
|
||
|
defaultObserver.start()
|
||
|
|