core-admin-client/qubesadmin/events/utils.py
Marek Marczykowski-Górecki b35588368f
events: add helper for waiting for just VM shutdown
Wrap setting events handling machinery for just this purpose in a single
function, to not duplicate it all over the code.
2017-05-26 00:42:47 +02:00

74 lines
2.4 KiB
Python

# -*- encoding: utf8 -*-
#
# The Qubes OS Project, http://www.qubes-os.org
#
# Copyright (C) 2017 Marek Marczykowski-Górecki
# <marmarek@invisiblethingslab.com>
#
# 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 2.1 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, see <http://www.gnu.org/licenses/>.
''' Utilities for common events-based actions '''
import asyncio
import functools
import qubesadmin.events
import qubesadmin.exc
class Interrupt(Exception):
'''Interrupt events processing'''
def interrupt_on_vm_shutdown(vm, subject, event):
'''Interrupt events processing when given VM was shutdown'''
# pylint: disable=unused-argument
if event == 'connection-established':
if vm.is_halted():
raise Interrupt
elif event == 'domain-shutdown' and vm == subject:
raise Interrupt
def wait_for_domain_shutdown(vm, timeout):
''' Helper function to wait for domain shutdown.
This function wait for domain shutdown, but do not initiate the shutdown
itself.
Note: you need to close event loop after calling this function.
:param vm: QubesVM object to wait for shutdown on
:param timeout: Timeout in seconds, use 0 for no timeout
'''
events = qubesadmin.events.EventsDispatcher(vm.app)
loop = asyncio.get_event_loop()
events.add_handler('domain-shutdown',
functools.partial(interrupt_on_vm_shutdown, vm))
events.add_handler('connection-established',
functools.partial(interrupt_on_vm_shutdown, vm))
events_task = asyncio.ensure_future(events.listen_for_events(),
loop=loop)
if timeout:
# pylint: disable=no-member
loop.call_later(timeout, events_task.cancel)
try:
loop.run_until_complete(events_task)
except asyncio.CancelledError:
raise qubesadmin.exc.QubesVMShutdownTimeout(
'VM %s shutdown timeout expired', vm.name)
except Interrupt:
pass