Source code for stoqlib.lib.daemonutils

# -*- coding: utf-8 -*-
# vi:si:et:sw=4:sts=4:ts=4

##
## Copyright (C) 2011-2016 Async Open Source
##
## This program is free software; you can redistribute it and/or
## modify it under the terms of the GNU Lesser 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 Lesser General Public License for more details.
##
## You should have received a copy of the GNU Lesser General Public License
## along with this program; if not, write to the Free Software
## Foundation, Inc., or visit: http://www.gnu.org/.
##
##
## Author(s): Stoq Team <stoq-devel@async.com.br>
##

import atexit
import logging
import multiprocessing
import os
import time

from stoqlib.net.socketutils import get_random_port
from stoqlib.lib.environment import is_developer_mode
from stoqlib.lib.threadutils import threadit

_daemon = None
_event = multiprocessing.Event()
log = logging.getLogger(__name__)


class Daemon(multiprocessing.Process):
    def __init__(self, port=None):
        super(Daemon, self).__init__()

        self.port = port
        if self.port is None and is_developer_mode():
            self.port = 8080
        elif self.port is None:
            self.port = get_random_port()
        # Indicate that this Thread is a daemon. Accordingly to the
        # documentation, the entire python program exits when no alive
        # non-daemon threads are left.
        self.daemon = True

    @property
    def running(self):
        return _event.wait()

    @property
    def server_uri(self):
        return 'http://localhost:%d' % (self.port, )

    #
    #  multiprocessing.Process
    #

    def run(self):
        self._ppid = os.getppid()
        threadit(self._check_parent_running)

        from stoqlib.net.webserver import run_server
        _event.set()
        run_server(self.port)

    #
    #  Private
    #

    def _check_parent_running(self):
        # When developing, we usually kill stoq a lot with something that
        # will not allow it to stop the daemon (e.g. ctrl+q, ctrl+4) so
        # it is better to do the check every 1 second. On production this
        # shouldn't happen often, but if it happens, it is ok to have it
        # running for another 5 seconds.
        sleep_time = 1 if is_developer_mode() else 5

        while self.is_alive():
            # If the parent dies, ppid will change. In this case,
            # finalize this process. It shouldn't be running anymore.
            if os.getppid() != self._ppid:
                os._exit(0)
            time.sleep(sleep_time)


def start_daemon():
    global _daemon
    if _daemon is None:
        _daemon = Daemon()
        log.debug('Starting deamon')
        _daemon.start()
    return _daemon


@atexit.register
def stop_daemon():
    global _daemon
    if _daemon is not None and _daemon.is_alive():
        log.debug('Stopping deamon')
        _daemon.terminate()
    _daemon = None