日誌列印之logging.config.dictConfig使用總結
By:授客 QQ:1033553122
#實踐環境
WIN 10
Python 3.6.5
#函式說明
logging.config.dictConfig(config)
dictConfig函式位於logging.config模組,該函式通過字典引數config對logging進行配置。3.2版本新增的函式
##引數說明
config 字典型別,包含以下key:
- version - 表示版本,該鍵值為從1開始的整數。該key必選,除此之外,其它key都是可選。
- formatters - 日誌格式化器,其value值為一個字典,該字典的每個鍵值對都代表一個Formatter,鍵值對中,key代表Formatter ID(自定義ID),value為字典,描述如何配置相應的Formatter例項。預設格式為 ‘%(message)s’
- filters - 日誌過濾器,其value值為一個字典,該字典的每個鍵值對都代表一個Filter,鍵值對中,key代表Filter ID(自定義ID),value為字典,描述如何配置相應的Filter例項。
- handlers - 日誌處理器,其value值為一個字典,該字典的每個鍵值對都代表一個Handler,鍵值對中,key代表Handler ID(自定義ID),value為字典,描述如何配置相應的Handler例項,包含以下配置key:
- class (必選). 日誌處理器類全稱
- level (可選). 指定該日誌處理器需要處理哪些級別的日誌,低於該級別的日誌將不被該handler處理。level可以為代表日誌級別的整數或者表大寫字串,字串日誌級別和數字日誌級別對應關係如下:
CRITICAL = 50
FATAL = CRITICAL
ERROR = 40
WARNING = 30
WARN = WARNING
INFO = 20
DEBUG = 10
NOTSET = 0
下同,不再贅述.
- formatter (可選). 指定該日誌處理器使用的日誌格式化器
- filters (可選). 制定該日誌處理器使用的日誌過濾器
# 上述的class配置項的值,可以使用自定義Handler類,此時,如果自定義Handler類的__init__建構函式還需要其它引數來初始化類例項,可以繼續添自定義引數,這些自定義引數被當做關鍵字引數會自動傳遞給建構函式。
一個例子:
"handlers": { "console":{ "class":"study.MyLogHandler", "formatter":"brief", "level":"INFO" }, "file": { "class": "logging.handlers.RotatingFileHandler", "formatter": "precise", "filename": "logconfig.log", "maxBytes": 1024, "backupCount": 3 } }
id為console的日誌處理器被例項化為一個logging.StreamHandler,使用sys.stout作為基礎例項流。id為file的日誌處理器則被例項化為具有關鍵字引數filename ='logconfig.log',maxBytes = 1024,backupCount = 3的 logging.handlers.RotatingFileHandler
- loggers - 日誌記錄器,其value值為一個字典,該字典的每個鍵值對都代表一個Handler,鍵值對中,key代表Handler ID,value為字典,描述如何配置相應的Logger例項,包含以下配置key:
- level (可選). 指定該日誌記錄器需要記錄哪些級別的日誌,低於該級別的日誌將不被該logger記錄。
- propagate (可選). 指定該日誌記錄器的propagation配置,為布林值,即True 或 False,用於控制是否向上遍歷父輩日誌列印器,進而控制當前日誌列印器是否共享父輩列印器的日誌處理器。True,向上遍歷,否則不向上遍歷。
- filters (可選). 指定該日誌記錄器使用的日誌過濾器
- handlers (可選). 制定該日誌記錄器使用的日誌處理器
- root - root logger配置。除了不支援propagate配置項以外,該配置的處理過程同處理其它logger的配置一樣,配置規則也一樣
- incremental - 用於判斷該config配置是否解釋為現有配置的增量配置,還是覆蓋原有配置。預設為False,即使用現有fileConfig()API使用的相同語義替換現有配置
- disable_existing_loggers - 其value為布林值,表示是否禁用現有日誌記錄器(root logger除外),預設值為True,即禁用。如果incremental 鍵值為True,則忽略該配置項
#程式碼示例1
study.py
study.py #!/usr/bin/env python # -*- coding:utf-8 -*- ''' @CreateTime: 2020/12/29 14:08 @Author : shouke ''' import logging import logging.config LOGGING_CONFIG = { "version": 1, "formatters": { "default": { 'format':'%(asctime)s %(filename)s %(lineno)s %(levelname)s %(message)s', }, "plain": { "format": "%(message)s", }, }, "handlers": { "console": { "class": "logging.StreamHandler", "level": "INFO", "formatter": "default", }, "console_plain": { "class": "logging.StreamHandler", "level":logging.INFO, "formatter": "plain" }, "file":{ "class": "logging.FileHandler", "level":20, "filename": "./log.txt", "formatter": "default", } }, "loggers": { "console_logger": { "handlers": ["console"], "level": "INFO", "propagate": False, }, "console_plain_logger": { "handlers": ["console_plain"], "level": "DEBUG", "propagate": False, }, "file_logger":{ "handlers": ["file"], "level": "INFO", "propagate": False, } }, "disable_existing_loggers": True, } # 執行測試 logging.config.dictConfig(LOGGING_CONFIG) logger = logging.getLogger("console_logger") logger.debug('debug message') logger.info('info message') logger.warn('warning message') logger.error('error message') logger.critical('critical message')
執行study.py,結果輸出如下
2021-01-09 10:01:59,123 study.py 66 INFO info message
2021-01-09 10:01:59,123 study.py 67 WARNING warning message
2021-01-09 10:01:59,123 study.py 68 ERROR error message
2021-01-09 10:01:59,123 study.py 69 CRITICAL critical message
#程式碼示例2
基於程式碼示例1,修改LOGGING_CONFIG及getLogger函式引數
LOGGING_CONFIG = { "version": 1, "formatters": { "default": { 'format':'%(asctime)s %(filename)s %(lineno)s %(levelname)s %(message)s', } }, "handlers": { "console": { "class": "logging.StreamHandler", "level": "INFO", "formatter": "default", } }, "disable_existing_loggers": True, "root": { "handlers": ["console"], "level": "DEBUG" }, } # 執行測試 logging.config.dictConfig(LOGGING_CONFIG) logger = logging.getLogger("root") logger.debug('debug message') logger.info('info message') logger.warn('warning message') logger.error('error message') logger.critical('critical message')
執行study.py,結果輸出如下
2021-01-09 10:33:03,456 study.py 38 INFO info message
2021-01-09 10:33:03,456 study.py 39 WARNING warning message
2021-01-09 10:33:03,456 study.py 40 ERROR error message
2021-01-09 10:33:03,456 study.py 41 CRITICAL critical message
# 原始碼的角度分析propagate配置項
Logger類,位於logging/__init__.py
class Logger(Filterer): #...略 def debug(self, msg, *args, **kwargs): """ Log 'msg % args' with severity 'DEBUG'. To pass exception information, use the keyword argument exc_info with a true value, e.g. logger.debug("Houston, we have a %s", "thorny problem", exc_info=1) """ if self.isEnabledFor(DEBUG): self._log(DEBUG, msg, args, **kwargs) def info(self, msg, *args, **kwargs): """ Log 'msg % args' with severity 'INFO'. To pass exception information, use the keyword argument exc_info with a true value, e.g. logger.info("Houston, we have a %s", "interesting problem", exc_info=1) """ if self.isEnabledFor(INFO): self._log(INFO, msg, args, **kwargs) #...略 def _log(self, level, msg, args, exc_info=None, extra=None, stack_info=False): """ Low-level logging routine which creates a LogRecord and then calls all the handlers of this logger to handle the record. """ sinfo = None if _srcfile: #IronPython doesn't track Python frames, so findCaller raises an #exception on some versions of IronPython. We trap it here so that #IronPython can use logging. try: fn, lno, func, sinfo = self.findCaller(stack_info) except ValueError: # pragma: no cover fn, lno, func = "(unknown file)", 0, "(unknown function)" else: # pragma: no cover fn, lno, func = "(unknown file)", 0, "(unknown function)" if exc_info: if isinstance(exc_info, BaseException): exc_info = (type(exc_info), exc_info, exc_info.__traceback__) elif not isinstance(exc_info, tuple): exc_info = sys.exc_info() record = self.makeRecord(self.name, level, fn, lno, msg, args, exc_info, func, extra, sinfo) self.handle(record) def handle(self, record): """ Call the handlers for the specified record. This method is used for unpickled records received from a socket, as well as those created locally. Logger-level filtering is applied. """ if (not self.disabled) and self.filter(record): self.callHandlers(record) def hasHandlers(self): """ See if this logger has any handlers configured. Loop through all handlers for this logger and its parents in the logger hierarchy. Return True if a handler was found, else False. Stop searching up the hierarchy whenever a logger with the "propagate" attribute set to zero is found - that will be the last logger which is checked for the existence of handlers. """ c = self rv = False while c: if c.handlers: rv = True break if not c.propagate: break else: c = c.parent return rv def callHandlers(self, record): """ Pass a record to all relevant handlers. Loop through all handlers for this logger and its parents in the logger hierarchy. If no handler was found, output a one-off error message to sys.stderr. Stop searching up the hierarchy whenever a logger with the "propagate" attribute set to zero is found - that will be the last logger whose handlers are called. """ c = self found = 0 while c: for hdlr in c.handlers: found = found + 1 if record.levelno >= hdlr.level: hdlr.handle(record) if not c.propagate: c = None #break out else: c = c.parent if (found == 0): if lastResort: if record.levelno >= lastResort.level: lastResort.handle(record) elif raiseExceptions and not self.manager.emittedNoHandlerWarning: sys.stderr.write("No handlers could be found for logger" " \"%s\"\n" % self.name) self.manager.emittedNoHandlerWarning = True
預設的,當通過logger.debug,logger.info的方式列印日誌時,會先判斷對應日誌級別是否開啟,如果開啟,則呼叫logger例項的_log方法,接著經過一連串的函式呼叫(self._log() -> self.handle -> self.callHandlers),如上,self.callHandlers中,會先遍歷當前日誌列印器自身的所有日誌處理器,處理日誌訊息,然後判斷propagate屬性是否為True,如果為True,則獲取上級日誌列印器,繼續遍歷其日誌處理器,處理訊息,否則不遍歷上級
另外,檢視hasHandlers函式可知,判斷一個logger是否有日誌處理器,也用到了propagate,如果propagate為True,則遍歷父級日誌列印器,看其是否存在日誌處理器,如果父級或者父輩日誌列印器存在日誌處理器,則判斷該logger擁有日誌處理器。
由此可見,propagate功能就是用於控制是否向上遍歷父輩日誌列印器,進而控制當前日誌列印器是否共享父輩列印器的日誌處理器。