log.py

# Copyright (C) 2003-2014 Bastian Kleineidam
#
# This program is free software; you can redistribute it and/or modify
# it under the terms of the GNU General Public License as published by
# the Free Software Foundation; either version 2 of the License, or
# (at your option) any later version.
#
# This program is distributed in the hope that it will be useful,
# but WITHOUT ANY WARRANTY; without even the implied warranty of
# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
# GNU General Public License for more details.
#
# You should have received a copy of the GNU General Public License along
# with this program; if not, write to the Free Software Foundation, Inc.,
# 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
"""
Logging and debug functions.
"""

from io import StringIO
import logging
import os
import inspect
import traceback

# memory leak debugging
# import gc
# gc.enable()
# gc.set_debug(gc.DEBUG_LEAK)

PRINT_LOCALVARS = False


def _stack_format(stack):
    """Format a stack trace to a message.

    @return: formatted stack message
    @rtype: string
    """
    s = StringIO()
    s.write('Traceback:')
    s.write(os.linesep)
    for frame, fname, lineno, method, lines, dummy in reversed(stack):
        s.write('  File %r, line %d, in %s' % (fname, lineno, method))
        s.write(os.linesep)
        s.write('    %s' % lines[0].lstrip())
        if PRINT_LOCALVARS:
            for key, value in frame.f_locals.items():
                s.write("      %s = " % key)
                # be careful not to cause a new error in the error output
                try:
                    s.write(repr(value))
                    s.write(os.linesep)
                except Exception:
                    s.write("error in repr() call%s" % os.linesep)
    return s.getvalue()


def _log(fun, msg, args, **kwargs):
    """Log a message with given function. Optional the following keyword
    arguments are supported:
    traceback(bool) - if True print traceback of current function
    exception(bool) - if True print last exception traceback

    @return: None
    """
    fun(msg, *args)
    if kwargs.get("traceback"):
        # note: get rid of last parts of the stack
        fun(_stack_format(inspect.stack()[2:]))
    if kwargs.get("exception"):
        fun(traceback.format_exc())


def debug(logname, msg, *args, **kwargs):
    """Log a debug message.

    return: None
    """
    log = logging.getLogger(logname)
    if log.isEnabledFor(logging.DEBUG):
        _log(log.debug, msg, args, **kwargs)


def info(logname, msg, *args, **kwargs):
    """Log an informational message.

    return: None
    """
    log = logging.getLogger(logname)
    if log.isEnabledFor(logging.INFO):
        _log(log.info, msg, args, **kwargs)


def warn(logname, msg, *args, **kwargs):
    """Log a warning.

    return: None
    """
    log = logging.getLogger(logname)
    if log.isEnabledFor(logging.WARN):
        _log(log.warning, msg, args, **kwargs)


def error(logname, msg, *args, **kwargs):
    """Log an error.

    return: None
    """
    log = logging.getLogger(logname)
    if log.isEnabledFor(logging.ERROR):
        _log(log.error, msg, args, **kwargs)


def critical(logname, msg, *args, **kwargs):
    """Log a critical error.

    return: None
    """
    log = logging.getLogger(logname)
    if log.isEnabledFor(logging.CRITICAL):
        _log(log.critical, msg, args, **kwargs)


def exception(logname, msg, *args, **kwargs):
    """Log an exception.

    return: None
    """
    log = logging.getLogger(logname)
    if log.isEnabledFor(logging.ERROR):
        _log(log.exception, msg, args, **kwargs)


def is_debug(logname):
    """See if logger is on debug level."""
    return logging.getLogger(logname).isEnabledFor(logging.DEBUG)


def shutdown():
    """Flush and close all log handlers."""
    logging.shutdown()