Python日志打印里logging.getLogger源码分析详解

 _loggerClass = Logger # ...略 root = RootLogger(WARNING) Logger.root = root Logger.manager = Manager(Logger.root) # ...略 def getLogger(name=None): """ Return a logger with the specified name, creating it if necessary. If no name is specified, return the root logger. """ if name: return Logger.manager.getLogger(name) else: return root

 class Manager(object): """ There is [under normal circumstances] just one Manager instance, which holds the hierarchy of loggers. """ def __init__(self, rootnode): """ Initialize the manager with the root node of the logger hierarchy. """ self.root = rootnode self.disable = 0 self.emittedNoHandlerWarning = False self.loggerDict = {} self.loggerClass = None self.logRecordFactory = None def getLogger(self, name): """ Get a logger with the specified name (channel name), creating it if it doesn't yet exist. This name is a dot-separated hierarchical name, such as "a", "a.b", "a.b.c" or similar. If a PlaceHolder existed for the specified name [i.e. the logger didn't exist but a child of it did], replace it with the created logger and fix up the parent/child references which pointed to the placeholder to now point to the logger. """ rv = None if not isinstance(name, str): raise TypeError('A logger name must be a string') _acquireLock() try: if name in self.loggerDict: rv = self.loggerDict[name] if isinstance(rv, PlaceHolder): ph = rv rv = (self.loggerClass or _loggerClass)(name) rv.manager = self self.loggerDict[name] = rv self._fixupChildren(ph, rv) self._fixupParents(rv) else: rv = (self.loggerClass or _loggerClass)(name) # _loggerClass = Logger rv.manager = self self.loggerDict[name] = rv self._fixupParents(rv) finally: _releaseLock<a style="color:transparent">来源gao($daima.com搞@代@#码(网</a>() return rv

 _nameToLevel = { 'CRITICAL': CRITICAL, 'FATAL': FATAL, 'ERROR': ERROR, 'WARN': WARNING, 'WARNING': WARNING, 'INFO': INFO, 'DEBUG': DEBUG, 'NOTSET': NOTSET, } # ...略 def _checkLevel(level): if isinstance(level, int): rv = level elif str(level) == level: if level not in _nameToLevel: raise ValueError("Unknown level: %r" % level) rv = _nameToLevel[level] else: raise TypeError("Level not an integer or a valid string: %r" % level) return rv # ...略 class PlaceHolder(object): """ PlaceHolder instances are used in the Manager logger hierarchy to take the place of nodes for which no loggers have been defined. This class is intended for internal use only and not as part of the public API. """ def __init__(self, alogger): """ Initialize with the specified logger being a child of this placeholder. """ self.loggerMap = { alogger : None } def append(self, alogger): """ Add the specified logger as a child of this placeholder. """ if alogger not in self.loggerMap: self.loggerMap[alogger] = None class Logger(Filterer): """ Instances of the Logger class represent a single logging channel. A "logging channel" indicates an area of an application. Exactly how an "area" is defined is up to the application developer. Since an application can have any number of areas, logging channels are identified by a unique string. Application areas can be nested (e.g. an area of "input processing" might include sub-areas "read CSV files", "read XLS files" and "read Gnumeric files"). To cater for this natural nesting, channel names are organized into a namespace hierarchy where levels are separated by periods, much like the Java or Python package namespace. So in the instance given above, channel names might be "input" for the upper level, and "input.csv", "input.xls" and "input.gnu" for the sub-levels. There is no arbitrary limit to the depth of nesting. """ def __init__(self, name, level=NOTSET): """ Initialize the logger with a name and an optional level. """ Filterer.__init__(self) self.name = name self.level = _checkLevel(level) self.parent = None self.propagate = True self.handlers = [] self.disabled = False # ... 略