On Wed, Nov 21, 2018 at 01:39:00PM -0500, Wainer dos Santos Moschetta wrote:
> QEMUMachine launches the VM with a monitor enabled, afterwards
> a qmp connection is attempted on _post_launch(). In case
> the QEMU process exits with an error, qmp.accept() reaches
> timeout and raises an exception.
>
> But sometimes you don't need that monitor. As an example,
> when a test launches the VM expects its immediate crash,
> and only intend to check the process's return code. In this
> case the fact that launch() tries to establish the qmp
> connection (ending up in an exception) is troublesome.
>
> So this patch adds the set_qmp_monitor() that allow to
> launch the VM without creating the monitor machinery. The
> method can be used to re-enable the monitor eventually.
>
> Tested this change with the following Avocado test:
>
> from avocado_qemu import Test
>
> class DisableQmp(Test):
I think it would be fine to have this test added as a real test instead
of just let this here on commit message. Or at least we should have a
real use case that uses this new feature.
> """
> :avocado: enable
> """
> def test(self):
> self.vm.add_args('--foobar')
> self.vm.set_qmp_monitor(disabled=True)
> self.vm.launch()
> self.vm.wait()
> self.assertEqual(self.vm.exitcode(), 1)
> self.vm.shutdown()
>
> self.vm.set_qmp_monitor(disabled=False)
> self.vm._args.remove('--foobar') # Hack
> self.vm.launch()
> res = self.vm.command('human-monitor-command',
> command_line='info version')
> self.assertRegexpMatches(res, r'^(\d+\.\d+\.\d)')
>
> Signed-off-by: Wainer dos Santos Moschetta <waine...@redhat.com>
> Reviewed-by: Caio Carrara <ccarr...@redhat.com>
> Reviewed-by: Eduardo Habkost <ehabk...@redhat.com>
> ---
> Changes in v2:
> * Major refactor: replaced disable_qmp() with set_qmp_monitor()
> that allow to disable the qmp monitor likewise, but also one can
> re-enable it (set_qmp_monitor(disabled=False)).
> * The logic to enabled/disable the monitor is back to
> _base_args(). [ccarrara, ehabkost]
> ---
> scripts/qemu.py | 72 ++++++++++++++++++++++++++++++++-----------------
> 1 file changed, 48 insertions(+), 24 deletions(-)
>
> diff --git a/scripts/qemu.py b/scripts/qemu.py
> index 6e3b0e6771..54fe0e65d2 100644
> --- a/scripts/qemu.py
> +++ b/scripts/qemu.py
> @@ -115,6 +115,7 @@ class QEMUMachine(object):
> self._events = []
> self._iolog = None
> self._socket_scm_helper = socket_scm_helper
> + self._with_qmp = True # Enable QMP monitor by default.
> self._qmp = None
> self._qemu_full_args = None
> self._test_dir = test_dir
> @@ -229,15 +230,7 @@ class QEMUMachine(object):
> self._iolog = iolog.read()
>
> def _base_args(self):
> - if isinstance(self._monitor_address, tuple):
> - moncdev = "socket,id=mon,host=%s,port=%s" % (
> - self._monitor_address[0],
> - self._monitor_address[1])
> - else:
> - moncdev = 'socket,id=mon,path=%s' % self._vm_monitor
> - args = ['-chardev', moncdev,
> - '-mon', 'chardev=mon,mode=control',
> - '-display', 'none', '-vga', 'none']
> + args = ['-display', 'none', '-vga', 'none']
> if self._machine is not None:
> args.extend(['-machine', self._machine])
> if self._console_device_type is not None:
> @@ -247,23 +240,33 @@ class QEMUMachine(object):
> self._console_address)
> device = '%s,chardev=console' % self._console_device_type
> args.extend(['-chardev', chardev, '-device', device])
> + if self._with_qmp:
> + if isinstance(self._monitor_address, tuple):
> + moncdev = "socket,id=mon,host=%s,port=%s" % (
> + self._monitor_address[0],
> + self._monitor_address[1])
> + else:
> + moncdev = 'socket,id=mon,path=%s' % self._vm_monitor
> + args.extend(['-chardev', moncdev, '-mon',
> 'chardev=mon,mode=control'])
> +
> return args
>
> def _pre_launch(self):
> self._temp_dir = tempfile.mkdtemp(dir=self._test_dir)
> - if self._monitor_address is not None:
> - self._vm_monitor = self._monitor_address
> - else:
> - self._vm_monitor = os.path.join(self._temp_dir,
> - self._name + "-monitor.sock")
> self._qemu_log_path = os.path.join(self._temp_dir, self._name +
> ".log")
> self._qemu_log_file = open(self._qemu_log_path, 'wb')
>
> - self._qmp = qmp.qmp.QEMUMonitorProtocol(self._vm_monitor,
> - server=True)
> -
> + if self._with_qmp:
> + if self._monitor_address is not None:
> + self._vm_monitor = self._monitor_address
> + else:
> + self._vm_monitor = os.path.join(self._temp_dir,
> + self._name + "-monitor.sock")
> + self._qmp = qmp.qmp.QEMUMonitorProtocol(self._vm_monitor,
> + server=True)
> def _post_launch(self):
> - self._qmp.accept()
> + if self._qmp:
> + self._qmp.accept()
>
> def _post_shutdown(self):
> if self._qemu_log_file is not None:
> @@ -325,7 +328,8 @@ class QEMUMachine(object):
> Wait for the VM to power off
> """
> self._popen.wait()
> - self._qmp.close()
> + if self._qmp:
Isn't the self._with_qmp attribute that should be used here? I think
it's important to standardize the checks for qmp availability in
`with_qmp` attribute and use the `qmp` only for qmp access itself. There
are other places that uses qmp to this kind of check too.
> + self._qmp.close()
> self._load_io_log()
> self._post_shutdown()
>
> @@ -334,11 +338,14 @@ class QEMUMachine(object):
> Terminate the VM and clean up
> """
> if self.is_running():
> - try:
> - self._qmp.cmd('quit')
> - self._qmp.close()
> - except:
> - self._popen.kill()
> + if self._qmp:
> + try:
> + self._qmp.cmd('quit')
> + self._qmp.close()
> + except:
> + self._popen.kill()
> + else:
> + self._popen.terminate()
> self._popen.wait()
>
> self._load_io_log()
> @@ -355,6 +362,23 @@ class QEMUMachine(object):
>
> self._launched = False
>
> + def set_qmp_monitor(self, disabled=False, monitor_address=None):
Where is this new method being used?
> + """
> + Set the QMP monitor.
> +
> + @param disabled: if True, qmp monitor options will be removed from
> the
> + base arguments of the resulting QEMU command line.
> + @param monitor_address: address for the QMP monitor.
> + @note: call this function before launch().
> + """
> + if disabled:
> + self._with_qmp = False
> + self._qmp = None
> + else:
> + self._with_qmp = True
> + if monitor_address:
> + self._monitor_address = monitor_address
> +
> def qmp(self, cmd, conv_keys=True, **args):
> """
> Invoke a QMP command and return the response dict
> --
> 2.19.1
>
It would be nice see less scattered checks for qmp availability along
the code.
Thanks.
--
Caio Carrara
Software Engineer, Virt Team - Red Hat
ccarr...@redhat.com
