# -*- coding: utf-8 -*-
# Copyright (c) 2010 Tom Burdick <thomas.burdick@gmail.com>
#
# Permission is hereby granted, free of charge, to any person obtaining a copy
# of this software and associated documentation files (the "Software"), to deal
# in the Software without restriction, including without limitation the rights
# to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
# copies of the Software, and to permit persons to whom the Software is
# furnished to do so, subject to the following conditions:
#
# The above copyright notice and this permission notice shall be included in
# all copies or substantial portions of the Software.
#
# THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
# IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
# FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
# AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
# LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
# OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
# THE SOFTWARE.

import gc
import pyev
import logbook

logger = logbook.Logger(__name__)

class ObjectWatcher(object):
    def __init__(self, loop, classes=[]):
        """Watches the garbage collector and prints out stats
        periodically with how many objects are in the gc for a given type.

        Useful for debugging situations where referrences are being held
        when they shouldn't be. A rather annoying problem in callback
        oriented code (that I've personally found anyways).

        """
        gc.set_debug(gc.DEBUG_STATS)
        self.classes = classes
        self.timer = pyev.Timer(5.0, 5.0, loop, self.print_stats)
        self.timer.start()

    def count(self, cls):
        return len([obj for obj in gc.get_objects() if isinstance(obj, cls)])

    def print_stats(self, watcher, events):
        gc.collect()
        logger.debug("Object Stats")
        for cls in self.classes:
            logger.debug("    %s : %d" % (cls.__name__, self.count(cls)))
