aea41511de
Application that runs EventsDispatcher can safely use also cache , which greatly improve performance. This is because cache then is properly updated/invalidated when needed. Instead of modifying each application to explicitly enable cache based on this simple rule, make it implicit when EventsDispatcher is created. Do not enable caching when EventsDispatcher is created only temporarily in wait_for_domain_shutdown. QubesOS/qubes-issues#3293
69 lines
2.1 KiB
Python
69 lines
2.1 KiB
Python
# -*- encoding: utf8 -*-
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#
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# The Qubes OS Project, http://www.qubes-os.org
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#
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# Copyright (C) 2017 Marek Marczykowski-Górecki
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# <marmarek@invisiblethingslab.com>
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#
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# This program is free software; you can redistribute it and/or modify
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# it under the terms of the GNU Lesser General Public License as published by
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# the Free Software Foundation; either version 2.1 of the License, or
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# (at your option) any later version.
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#
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# This program is distributed in the hope that it will be useful,
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# but WITHOUT ANY WARRANTY; without even the implied warranty of
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# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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# GNU Lesser General Public License for more details.
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#
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# You should have received a copy of the GNU Lesser General Public License along
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# with this program; if not, see <http://www.gnu.org/licenses/>.
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''' Utilities for common events-based actions '''
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import asyncio
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import functools
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import qubesadmin.events
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import qubesadmin.exc
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class Interrupt(Exception):
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'''Interrupt events processing'''
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def interrupt_on_vm_shutdown(vms, subject, event):
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'''Interrupt events processing when given VM was shutdown'''
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# pylint: disable=unused-argument
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if event == 'connection-established':
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if all(vm.is_halted() for vm in sorted(vms)):
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raise Interrupt
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elif event == 'domain-shutdown' and subject in vms:
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vms.remove(subject)
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if not vms:
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raise Interrupt
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@asyncio.coroutine
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def wait_for_domain_shutdown(vms):
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''' Helper function to wait for domain shutdown.
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This function wait for domain shutdown, but do not initiate the shutdown
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itself.
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:param vms: QubesVM object collection to wait for shutdown on
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'''
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if not vms:
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return
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app = list(vms)[0].app
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vms = set(vms)
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events = qubesadmin.events.EventsDispatcher(app, enable_cache=False)
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events.add_handler('domain-shutdown',
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functools.partial(interrupt_on_vm_shutdown, vms))
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events.add_handler('connection-established',
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functools.partial(interrupt_on_vm_shutdown, vms))
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try:
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yield from events.listen_for_events()
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except Interrupt:
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pass
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