gns3-server/gns3server/notification_queue.py

#!/usr/bin/env python
#
# Copyright (C) 2016 GNS3 Technologies Inc.
#
# 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 3 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, see <http://www.gnu.org/licenses/>.

import asyncio
import json
import psutil

from gns3server.utils.cpu_percent import CpuPercent

import logging
log = logging.getLogger(__name__)


class NotificationQueue(asyncio.Queue):
    """
    Queue returned by the notification manager.
    """

    def __init__(self):
        super().__init__()
        self._first = True

    async def get(self, timeout):
        """
        When timeout is expire we send a ping notification with server information
        """

        # At first get we return a ping so the client immediately receives data
        if self._first:
            self._first = False
            return ("ping", self._getPing(), {})

        try:
            (action, msg, kwargs) = await asyncio.wait_for(super().get(), timeout)
        except asyncio.TimeoutError:
            return ("ping", self._getPing(), {})
        return (action, msg, kwargs)

    def _getPing(self):
        """
        Return the content of the ping notification
        """
        msg = {"cpu_usage_percent": 0,
               "memory_usage_percent": 0}
        # Non blocking call in order to get cpu usage. First call will return 0
        try:
            msg["cpu_usage_percent"] = CpuPercent.get(interval=None)
            msg["memory_usage_percent"] = psutil.virtual_memory().percent
        except OSError as e:
            log.warning("Could not get CPU and memory usage from psutil: {}".format(e))
        return msg

    async def get_json(self, timeout):
        """
        Get a message as a JSON
        """
        (action, msg, kwargs) = await self.get(timeout)
        if hasattr(msg, "__json__"):
            msg = {"action": action, "event": msg.__json__()}
        else:
            msg = {"action": action, "event": msg}
        msg.update(kwargs)
        return json.dumps(msg, sort_keys=True)