Python内置日志模块源码分析和进阶用法

class StreamHandler(Handler):
    """
    A handler class which writes logging records, appropriately formatted,
    to a stream. Note that this class does not close the stream, as
    sys.stdout or sys.stderr may be used.
    """

class FileHandler(StreamHandler):
    """
    A handler class which writes formatted logging records to disk files.
    """

    def emit(self, record):
        """
        Do whatever it takes to actually log the specified logging record.

        This version is intended to be implemented by subclasses and so
        raises a NotImplementedError.
        """
        raise NotImplementedError('emit must be implemented '
                                  'by Handler subclasses')

class TimedRotatingFileHandler(BaseRotatingHandler):
    """
    Handler for logging to a file, rotating the log file at certain timed
    intervals.

    If backupCount is > 0, when rollover is done, no more than backupCount
    files are kept - the oldest ones are deleted.
    """
    def __init__(self, filename, when='h', interval=1, backupCount=0, encoding=None, delay=False, utc=False, atTime=None):
        BaseRotatingHandler.__init__(self, filename, 'a', encoding, delay)
        self.when = when.upper()
        self.backupCount = backupCount
        self.utc = utc
        self.atTime = atTime
        # Calculate the real rollover interval, which is just the number of
        # seconds between rollovers.  Also set the filename suffix used when
        # a rollover occurs.  Current 'when' events supported:
        # S - Seconds
        # M - Minutes
        # H - Hours
        # D - Days
        # midnight - roll over at midnight
        # W{0-6} - roll over on a certain day; 0 - Monday
        #
        # Case of the 'when' specifier is not important; lower or upper case
        # will work.
        if self.when == 'S':
            self.interval = 1 # one second
            self.suffix = "%Y-%m-%d_%H-%M-%S"
            self.extMatch = r"^\d{4}-\d{2}-\d{2}_\d{2}-\d{2}-\d{2}(\.\w+)?$"
        elif self.when == 'M':
            self.interval = 60 # one minute
            self.suffix = "%Y-%m-%d_%H-%M"
            self.extMatch = r"^\d{4}-\d{2}-\d{2}_\d{2}-\d{2}(\.\w+)?$"
        elif self.when == 'H':
            self.interval = 60 * 60 # one hour
            self.suffix = "%Y-%m-%d_%H"
            self.extMatch = r"^\d{4}-\d{2}-\d{2}_\d{2}(\.\w+)?$"
        elif self.when == 'D' or self.when == 'MIDNIGHT':
            self.interval = 60 * 60 * 24 # one day
            self.suffix = "%Y-%m-%d"
            self.extMatch = r"^\d{4}-\d{2}-\d{2}(\.\w+)?$"
        elif self.when.startswith('W'):
            self.interval = 60 * 60 * 24 * 7 # one week
            if len(self.when) != 2:
                raise ValueError("You must specify a day for weekly rollover from 0 to 6 (0 is Monday): %s" % self.when)
            if self.when[1] < '0' or self.when[1] > '6':
                raise ValueError("Invalid day specified for weekly rollover: %s" % self.when)
            self.dayOfWeek = int(self.when[1])
            self.suffix = "%Y-%m-%d"
            self.extMatch = r"^\d{4}-\d{2}-\d{2}(\.\w+)?$"
        else:
            raise ValueError("Invalid rollover interval specified: %s" % self.when)

        self.extMatch = re.compile(self.extMatch, re.ASCII)
        self.interval = self.interval * interval # multiply by units requested
        # The following line added because the filename passed in could be a
        # path object (see Issue #27493), but self.baseFilename will be a string
        filename = self.baseFilename
        if os.path.exists(filename):
            t = os.stat(filename)[ST_MTIME]
        else:
            t = int(time.time())
        self.rolloverAt = self.computeRollover(t)

# ......................

#---------------------------------------------------------------------------
#   Thread-related stuff
#---------------------------------------------------------------------------

#
#_lock is used to serialize access to shared data structures in this module.
#This needs to be an RLock because fileConfig() creates and configures
#Handlers, and so might arbitrary user threads. Since Handler code updates the
#shared dictionary _handlers, it needs to acquire the lock. But if configuring,
#the lock would already have been acquired - so we need an RLock.
#The same argument applies to Loggers and Manager.loggerDict.
#
_lock = threading.RLock()

def _acquireLock():
    """
    Acquire the module-level lock for serializing access to shared data.

    This should be released with _releaseLock().
    """
    if _lock:
        _lock.acquire()

def _releaseLock():
    """
    Release the module-level lock acquired by calling _acquireLock().
    """
    if _lock:
        _lock.release()

PROPERTY_EXTRA_ID = "extra_id"



class DBHandler(logging.Handler):
    """将日志内容写入到数据库中"""

    def __init__(self, level=logging.NOTSET):
        """
        初始化数据库
        """
        super().__init__(level=level)
        self.logdao = BusinessDAO(db_config=config.DB_CONFIG_PATH)
        self.logdb = self.logdao.connect_db()
        self.session = self.logdb.get_session()

    def emit(self, record: logging.LogRecord) -> None:
        """
        重写emit方法，将record记录到数据库中
        :param record:
        :return:
        """
        try:
            self.session.add(Log(level_name=record.levelname,
                                 module=record.module,
                                 thread_name=record.threadName,
                                 file_name=record.filename,
                                 func_name=record.funcName,
                                 line_no=record.lineno,
                                 process=record.process,
                                 process_name=record.processName,
                                 content=record.message,
                                 extra_id=getattr(record, PROPERTY_EXTRA_ID, None),
                                 created_time=datetime.datetime.strptime(record.asctime, DATE_FORMAT)
                                 ))
            self.session.commit()
        except Exception as e:
            print("Log to DB failed...", repr(e))

    def __del__(self):
        self.session.close()