自定义记录器类和日志中正确的行号/函数名

Question

我想将Python logger封装在一个自定义类中，以嵌入一些特定于应用程序的功能，并向开发人员隐藏设置细节（设置文件输出、日志级别等）。为此，我使用以下API创建了一个类：

__init__(log_level, filename)
debug(msg)
info(msg)
warning(msg)
error(msg)

logger.debug/info/warning/etc调用通常在日志中写入进行日志调用的函数和行号。但是，使用我的自定义类，写入日志文件的函数和行号总是相同的（对应于自定义类中的debug（）/info（）/警告（）/错误（）函数）。我想让它保存记录msg的应用程序代码行。那有可能吗？

提前谢谢。

Answer 1

是：sys_getframe（NUM）其中NUM表示当前函数之外的函数数量。返回的帧对象具有f_lineno和f_code等属性。co_文件名。

http://docs.python.org/library/sys.html#sys._getframe

Answer 2

基于威尔·威尔的回答。另一个选项是覆盖findCaller方法并使用自定义类作为默认记录器：

class MyLogger(logging.Logger):
    """
        Needs to produce correct line numbers
    """
    def findCaller(self):
        n_frames_upper = 2
        f = logging.currentframe()
        for _ in range(2 + n_frames_upper):  # <-- correct frame
            if f is not None:
                f = f.f_back
        rv = "(unknown file)", 0, "(unknown function)"
        while hasattr(f, "f_code"):
            co = f.f_code
            filename = os.path.normcase(co.co_filename)
            if filename == logging._srcfile:
                f = f.f_back
                continue
            rv = (co.co_filename, f.f_lineno, co.co_name)
            break
        return rv

logging.setLoggerClass(MyLogger)
logger = logging.getLogger('MyLogger')  # init MyLogger
logging.setLoggerClass(logging.Logger) # reset logger class to default

Answer 3

如果您愿意重新实现一点标准日志模块，就可以生成日志包装器。诀窍是编写自己的findCaller（）方法，该方法知道在解释回溯跟踪时如何忽略日志包装器源文件。

在logwrapper中。py:

import logging
import os
import sys

from logging import *


# This code is mainly copied from the python logging module, with minor modifications

# _srcfile is used when walking the stack to check when we've got the first
# caller stack frame.
#
if hasattr(sys, 'frozen'): #support for py2exe
    _srcfile = "logging%s__init__%s" % (os.sep, __file__[-4:])
elif __file__[-4:].lower() in ['.pyc', '.pyo']:
    _srcfile = __file__[:-4] + '.py'
else:
    _srcfile = __file__
_srcfile = os.path.normcase(_srcfile)


class LogWrapper(object):
    def __init__(self, logger):
        self.logger = logger

    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.logger.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.logger.isEnabledFor(INFO):
            self._log(INFO, msg, args, **kwargs)


    # Add other convenience methods

    def log(self, level, msg, *args, **kwargs):
        """
        Log 'msg % args' with the integer severity 'level'.

        To pass exception information, use the keyword argument exc_info with
        a true value, e.g.

        logger.log(level, "We have a %s", "mysterious problem", exc_info=1)
        """
        if not isinstance(level, int):
            if logging.raiseExceptions:
                raise TypeError("level must be an integer")
            else:
                return
        if self.logger.isEnabledFor(level):
            self._log(level, msg, args, **kwargs)


    def _log(self, level, msg, args, exc_info=None, extra=None):
        """
        Low-level logging routine which creates a LogRecord and then calls
        all the handlers of this logger to handle the record.
        """
        # Add wrapping functionality here.
        if _srcfile:
            #IronPython doesn't track Python frames, so findCaller throws an
            #exception on some versions of IronPython. We trap it here so that
            #IronPython can use logging.
            try:
                fn, lno, func = self.findCaller()
            except ValueError:
                fn, lno, func = "(unknown file)", 0, "(unknown function)"
        else:
            fn, lno, func = "(unknown file)", 0, "(unknown function)"
        if exc_info:
            if not isinstance(exc_info, tuple):
                exc_info = sys.exc_info()
        record = self.logger.makeRecord(
            self.logger.name, level, fn, lno, msg, args, exc_info, func, extra)
        self.logger.handle(record)


    def findCaller(self):
        """
        Find the stack frame of the caller so that we can note the source
        file name, line number and function name.
        """
        f = logging.currentframe()
        #On some versions of IronPython, currentframe() returns None if
        #IronPython isn't run with -X:Frames.
        if f is not None:
            f = f.f_back
        rv = "(unknown file)", 0, "(unknown function)"
        while hasattr(f, "f_code"):
            co = f.f_code
            filename = os.path.normcase(co.co_filename)
            if filename == _srcfile:
                f = f.f_back
                continue
            rv = (co.co_filename, f.f_lineno, co.co_name)
            break
        return rv

还有一个使用它的例子：

import logging
from logwrapper import LogWrapper

logging.basicConfig(level=logging.DEBUG, format="%(asctime)s %(filename)s(%(lineno)d): "
                    "%(message)s")
logger = logging.getLogger()
lw = LogWrapper(logger)

lw.info('Wrapped well, this is interesting')