# -*- test-case-name: twisted.test.test_log -*- # Copyright (c) Twisted Matrix Laboratories. # See LICENSE for details. """ Logging and metrics infrastructure. """ from __future__ import division, absolute_import import sys import time import warnings from datetime import datetime from zope.interface import Interface from twisted.python.compat import unicode, _PY3 from twisted.python import context from twisted.python import reflect from twisted.python import util from twisted.python import failure from twisted.python._oldstyle import _oldStyle from twisted.python.threadable import synchronize from twisted.logger import ( Logger as NewLogger, LogLevel as NewLogLevel, STDLibLogObserver as NewSTDLibLogObserver, LegacyLogObserverWrapper, LoggingFile, LogPublisher as NewPublisher, globalLogPublisher as newGlobalLogPublisher, globalLogBeginner as newGlobalLogBeginner, ) from twisted.logger._global import LogBeginner from twisted.logger._legacy import publishToNewObserver as _publishNew @_oldStyle class ILogContext: """ Actually, this interface is just a synonym for the dictionary interface, but it serves as a key for the default information in a log. I do not inherit from C{Interface} because the world is a cruel place. """ class ILogObserver(Interface): """ An observer which can do something with log events. Given that most log observers are actually bound methods, it's okay to not explicitly declare provision of this interface. """ def __call__(eventDict): """ Log an event. @type eventDict: C{dict} with C{str} keys. @param eventDict: A dictionary with arbitrary keys. However, these keys are often available: - C{message}: A C{tuple} of C{str} containing messages to be logged. - C{system}: A C{str} which indicates the "system" which is generating this event. - C{isError}: A C{bool} indicating whether this event represents an error. - C{failure}: A L{failure.Failure} instance - C{why}: Used as header of the traceback in case of errors. - C{format}: A string format used in place of C{message} to customize the event. The intent is for the observer to format a message by doing something like C{format % eventDict}. """ context.setDefault(ILogContext, {"system": "-"}) def callWithContext(ctx, func, *args, **kw): newCtx = context.get(ILogContext).copy() newCtx.update(ctx) return context.call({ILogContext: newCtx}, func, *args, **kw) def callWithLogger(logger, func, *args, **kw): """ Utility method which wraps a function in a try:/except:, logs a failure if one occurs, and uses the system's logPrefix. """ try: lp = logger.logPrefix() except KeyboardInterrupt: raise except: lp = '(buggy logPrefix method)' err(system=lp) try: return callWithContext({"system": lp}, func, *args, **kw) except KeyboardInterrupt: raise except: err(system=lp) def err(_stuff=None, _why=None, **kw): """ Write a failure to the log. The C{_stuff} and C{_why} parameters use an underscore prefix to lessen the chance of colliding with a keyword argument the application wishes to pass. It is intended that they be supplied with arguments passed positionally, not by keyword. @param _stuff: The failure to log. If C{_stuff} is L{None} a new L{Failure} will be created from the current exception state. If C{_stuff} is an C{Exception} instance it will be wrapped in a L{Failure}. @type _stuff: L{None}, C{Exception}, or L{Failure}. @param _why: The source of this failure. This will be logged along with C{_stuff} and should describe the context in which the failure occurred. @type _why: C{str} """ if _stuff is None: _stuff = failure.Failure() if isinstance(_stuff, failure.Failure): msg(failure=_stuff, why=_why, isError=1, **kw) elif isinstance(_stuff, Exception): msg(failure=failure.Failure(_stuff), why=_why, isError=1, **kw) else: msg(repr(_stuff), why=_why, isError=1, **kw) deferr = err @_oldStyle class Logger: """ This represents a class which may 'own' a log. Used by subclassing. """ def logPrefix(self): """ Override this method to insert custom logging behavior. Its return value will be inserted in front of every line. It may be called more times than the number of output lines. """ return '-' @_oldStyle class LogPublisher: """ Class for singleton log message publishing. """ synchronized = ['msg'] def __init__(self, observerPublisher=None, publishPublisher=None, logBeginner=None, warningsModule=warnings): if publishPublisher is None: publishPublisher = NewPublisher() if observerPublisher is None: observerPublisher = publishPublisher if observerPublisher is None: observerPublisher = NewPublisher() self._observerPublisher = observerPublisher self._publishPublisher = publishPublisher self._legacyObservers = [] if logBeginner is None: # This default behavior is really only used for testing. beginnerPublisher = NewPublisher() beginnerPublisher.addObserver(observerPublisher) logBeginner = LogBeginner(beginnerPublisher, NullFile(), sys, warnings) self._logBeginner = logBeginner self._warningsModule = warningsModule self._oldshowwarning = warningsModule.showwarning self.showwarning = self._logBeginner.showwarning @property def observers(self): """ Property returning all observers registered on this L{LogPublisher}. @return: observers previously added with L{LogPublisher.addObserver} @rtype: L{list} of L{callable} """ return [x.legacyObserver for x in self._legacyObservers] def _startLogging(self, other, setStdout): """ Begin logging to the L{LogBeginner} associated with this L{LogPublisher}. @param other: the observer to log to. @type other: L{LogBeginner} @param setStdout: if true, send standard I/O to the observer as well. @type setStdout: L{bool} """ wrapped = LegacyLogObserverWrapper(other) self._legacyObservers.append(wrapped) self._logBeginner.beginLoggingTo([wrapped], True, setStdout) def _stopLogging(self): """ Clean-up hook for fixing potentially global state. Only for testing of this module itself. If you want less global state, use the new warnings system in L{twisted.logger}. """ if self._warningsModule.showwarning == self.showwarning: self._warningsModule.showwarning = self._oldshowwarning def addObserver(self, other): """ Add a new observer. @type other: Provider of L{ILogObserver} @param other: A callable object that will be called with each new log message (a dict). """ wrapped = LegacyLogObserverWrapper(other) self._legacyObservers.append(wrapped) self._observerPublisher.addObserver(wrapped) def removeObserver(self, other): """ Remove an observer. """ for observer in self._legacyObservers: if observer.legacyObserver == other: self._legacyObservers.remove(observer) self._observerPublisher.removeObserver(observer) break def msg(self, *message, **kw): """ Log a new message. The message should be a native string, i.e. bytes on Python 2 and Unicode on Python 3. For compatibility with both use the native string syntax, for example:: >>> log.msg('Hello, world.') You MUST avoid passing in Unicode on Python 2, and the form:: >>> log.msg('Hello ', 'world.') This form only works (sometimes) by accident. Keyword arguments will be converted into items in the event dict that is passed to L{ILogObserver} implementations. Each implementation, in turn, can define keys that are used by it specifically, in addition to common keys listed at L{ILogObserver.__call__}. For example, to set the C{system} parameter while logging a message:: >>> log.msg('Started', system='Foo') """ actualEventDict = (context.get(ILogContext) or {}).copy() actualEventDict.update(kw) actualEventDict['message'] = message actualEventDict['time'] = time.time() if "isError" not in actualEventDict: actualEventDict["isError"] = 0 _publishNew(self._publishPublisher, actualEventDict, textFromEventDict) synchronize(LogPublisher) if 'theLogPublisher' not in globals(): def _actually(something): """ A decorator that returns its argument rather than the thing it is decorating. This allows the documentation generator to see an alias for a method or constant as an object with a docstring and thereby document it and allow references to it statically. @param something: An object to create an alias for. @type something: L{object} @return: a 1-argument callable that returns C{something} @rtype: L{object} """ def decorate(thingWithADocstring): return something return decorate theLogPublisher = LogPublisher( observerPublisher=newGlobalLogPublisher, publishPublisher=newGlobalLogPublisher, logBeginner=newGlobalLogBeginner, ) @_actually(theLogPublisher.addObserver) def addObserver(observer): """ Add a log observer to the global publisher. @see: L{LogPublisher.addObserver} @param observer: a log observer @type observer: L{callable} """ @_actually(theLogPublisher.removeObserver) def removeObserver(observer): """ Remove a log observer from the global publisher. @see: L{LogPublisher.removeObserver} @param observer: a log observer previously added with L{addObserver} @type observer: L{callable} """ @_actually(theLogPublisher.msg) def msg(*message, **event): """ Publish a message to the global log publisher. @see: L{LogPublisher.msg} @param message: the log message @type message: C{tuple} of L{str} (native string) @param event: fields for the log event @type event: L{dict} mapping L{str} (native string) to L{object} """ @_actually(theLogPublisher.showwarning) def showwarning(): """ Publish a Python warning through the global log publisher. @see: L{LogPublisher.showwarning} """ def _safeFormat(fmtString, fmtDict): """ Try to format a string, swallowing all errors to always return a string. @note: For backward-compatibility reasons, this function ensures that it returns a native string, meaning C{bytes} in Python 2 and C{unicode} in Python 3. @param fmtString: a C{%}-format string @param fmtDict: string formatting arguments for C{fmtString} @return: A native string, formatted from C{fmtString} and C{fmtDict}. @rtype: L{str} """ # There's a way we could make this if not safer at least more # informative: perhaps some sort of str/repr wrapper objects # could be wrapped around the things inside of C{fmtDict}. That way # if the event dict contains an object with a bad __repr__, we # can only cry about that individual object instead of the # entire event dict. try: text = fmtString % fmtDict except KeyboardInterrupt: raise except: try: text = ('Invalid format string or unformattable object in ' 'log message: %r, %s' % (fmtString, fmtDict)) except: try: text = ('UNFORMATTABLE OBJECT WRITTEN TO LOG with fmt %r, ' 'MESSAGE LOST' % (fmtString,)) except: text = ('PATHOLOGICAL ERROR IN BOTH FORMAT STRING AND ' 'MESSAGE DETAILS, MESSAGE LOST') # Return a native string if _PY3: if isinstance(text, bytes): text = text.decode("utf-8") else: if isinstance(text, unicode): text = text.encode("utf-8") return text def textFromEventDict(eventDict): """ Extract text from an event dict passed to a log observer. If it cannot handle the dict, it returns None. The possible keys of eventDict are: - C{message}: by default, it holds the final text. It's required, but can be empty if either C{isError} or C{format} is provided (the first having the priority). - C{isError}: boolean indicating the nature of the event. - C{failure}: L{failure.Failure} instance, required if the event is an error. - C{why}: if defined, used as header of the traceback in case of errors. - C{format}: string format used in place of C{message} to customize the event. It uses all keys present in C{eventDict} to format the text. Other keys will be used when applying the C{format}, or ignored. """ edm = eventDict['message'] if not edm: if eventDict['isError'] and 'failure' in eventDict: why = eventDict.get('why') if why: why = reflect.safe_str(why) else: why = 'Unhandled Error' try: traceback = eventDict['failure'].getTraceback() except Exception as e: traceback = '(unable to obtain traceback): ' + str(e) text = (why + '\n' + traceback) elif 'format' in eventDict: text = _safeFormat(eventDict['format'], eventDict) else: # We don't know how to log this return None else: text = ' '.join(map(reflect.safe_str, edm)) return text @_oldStyle class _GlobalStartStopMixIn: """ Mix-in for global log observers that can start and stop. """ def start(self): """ Start observing log events. """ addObserver(self.emit) def stop(self): """ Stop observing log events. """ removeObserver(self.emit) class FileLogObserver(_GlobalStartStopMixIn): """ Log observer that writes to a file-like object. @type timeFormat: C{str} or L{None} @ivar timeFormat: If not L{None}, the format string passed to strftime(). """ timeFormat = None def __init__(self, f): # Compatibility self.write = f.write self.flush = f.flush def getTimezoneOffset(self, when): """ Return the current local timezone offset from UTC. @type when: C{int} @param when: POSIX (ie, UTC) timestamp for which to find the offset. @rtype: C{int} @return: The number of seconds offset from UTC. West is positive, east is negative. """ offset = datetime.utcfromtimestamp(when) - datetime.fromtimestamp(when) return offset.days * (60 * 60 * 24) + offset.seconds def formatTime(self, when): """ Format the given UTC value as a string representing that time in the local timezone. By default it's formatted as an ISO8601-like string (ISO8601 date and ISO8601 time separated by a space). It can be customized using the C{timeFormat} attribute, which will be used as input for the underlying L{datetime.datetime.strftime} call. @type when: C{int} @param when: POSIX (ie, UTC) timestamp for which to find the offset. @rtype: C{str} """ if self.timeFormat is not None: return datetime.fromtimestamp(when).strftime(self.timeFormat) tzOffset = -self.getTimezoneOffset(when) when = datetime.utcfromtimestamp(when + tzOffset) tzHour = abs(int(tzOffset / 60 / 60)) tzMin = abs(int(tzOffset / 60 % 60)) if tzOffset < 0: tzSign = '-' else: tzSign = '+' return '%d-%02d-%02d %02d:%02d:%02d%s%02d%02d' % ( when.year, when.month, when.day, when.hour, when.minute, when.second, tzSign, tzHour, tzMin) def emit(self, eventDict): """ Format the given log event as text and write it to the output file. @param eventDict: a log event @type eventDict: L{dict} mapping L{str} (native string) to L{object} """ text = textFromEventDict(eventDict) if text is None: return timeStr = self.formatTime(eventDict["time"]) fmtDict = { "system": eventDict["system"], "text": text.replace("\n", "\n\t") } msgStr = _safeFormat("[%(system)s] %(text)s\n", fmtDict) util.untilConcludes(self.write, timeStr + " " + msgStr) util.untilConcludes(self.flush) # Hoorj! class PythonLoggingObserver(_GlobalStartStopMixIn, object): """ Output twisted messages to Python standard library L{logging} module. WARNING: specific logging configurations (example: network) can lead to a blocking system. Nothing is done here to prevent that, so be sure to not use this: code within Twisted, such as twisted.web, assumes that logging does not block. """ def __init__(self, loggerName="twisted"): """ @param loggerName: identifier used for getting logger. @type loggerName: C{str} """ self._newObserver = NewSTDLibLogObserver(loggerName) def emit(self, eventDict): """ Receive a twisted log entry, format it and bridge it to python. By default the logging level used is info; log.err produces error level, and you can customize the level by using the C{logLevel} key:: >>> log.msg('debugging', logLevel=logging.DEBUG) """ if 'log_format' in eventDict: _publishNew(self._newObserver, eventDict, textFromEventDict) @_oldStyle 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 = '' 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) 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, LoggingFile): 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. """ theLogPublisher._startLogging(observer, setStdout) msg("Log opened.") @_oldStyle class NullFile: """ A file-like object that discards everything. """ softspace = 0 def read(self): """ Do nothing. """ def write(self, bytes): """ Do nothing. @param bytes: data @type bytes: L{bytes} """ def flush(self): """ Do nothing. """ def close(self): """ Do nothing. """ def discardLogs(): """ Discard messages logged via the global C{logfile} object. """ global logfile logfile = NullFile() # Prevent logfile from being erased on reload. This only works in cpython. if 'logfile' not in globals(): logfile = LoggingFile(logger=NewLogger(), level=NewLogLevel.info, encoding=getattr(sys.stdout, "encoding", None)) logerr = LoggingFile(logger=NewLogger(), level=NewLogLevel.error, encoding=getattr(sys.stderr, "encoding", None)) class DefaultObserver(_GlobalStartStopMixIn): """ 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): """ Emit an event dict. @param eventDict: an event dict @type eventDict: dict """ if eventDict["isError"]: text = textFromEventDict(eventDict) self.stderr.write(text) self.stderr.flush() if 'defaultObserver' not in globals(): defaultObserver = DefaultObserver()