Re: [Qemu-devel] [PATCH 1/2] QMP: add get_events(wait=True) option

[Luiz Capitulino <lcapitulino@redhat.com>]

On Thu, 26 May 2011 09:03:49 +0100
Stefan Hajnoczi <stefanha@gmail.com> wrote:

> On Wed, May 25, 2011 at 10:15 PM, Luiz Capitulino
> <lcapitulino@redhat.com> wrote:
> > On Wed, 25 May 2011 19:48:00 +0100
> > Stefan Hajnoczi <stefanha@linux.vnet.ibm.com> wrote:
> >
> >> The get_events() function polls for new QMP events and then returns.  It
> >> can be useful to wait for the next QMP event so add the boolean 'wait'
> >> keyword argument.
> >>
> >> Signed-off-by: Stefan Hajnoczi <stefanha@linux.vnet.ibm.com>
> >> ---
> >>  QMP/qmp.py |   11 ++++++++---
> >>  1 files changed, 8 insertions(+), 3 deletions(-)
> >>
> >> diff --git a/QMP/qmp.py b/QMP/qmp.py
> >> index 14ce8b0..2565508 100644
> >> --- a/QMP/qmp.py
> >> +++ b/QMP/qmp.py
> >> @@ -43,7 +43,7 @@ class QEMUMonitorProtocol:
> >>              family = socket.AF_UNIX
> >>          return socket.socket(family, socket.SOCK_STREAM)
> >>
> >> -    def __json_read(self):
> >> +    def __json_read(self, only_event=False):
> >>          while True:
> >>              data = self.__sockfile.readline()
> >>              if not data:
> >> @@ -51,7 +51,8 @@ class QEMUMonitorProtocol:
> >>              resp = json.loads(data)
> >>              if 'event' in resp:
> >>                  self.__events.append(resp)
> >> -                continue
> >> +                if not only_event:
> >> +                    continue
> >>              return resp
> >>
> >>      error = socket.error
> >> @@ -106,9 +107,11 @@ class QEMUMonitorProtocol:
> >>              qmp_cmd['id'] = id
> >>          return self.cmd_obj(qmp_cmd)
> >>
> >> -    def get_events(self):
> >> +    def get_events(self, wait=False):
> >>          """
> >>          Get a list of available QMP events.
> >> +
> >> +        @param wait: block until an event is available (bool)
> >>          """
> >>          self.__sock.setblocking(0)
> >>          try:
> >> @@ -118,6 +121,8 @@ class QEMUMonitorProtocol:
> >>                  # No data available
> >>                  pass
> >>          self.__sock.setblocking(1)
> >> +        if not self.__events and wait:
> >> +            self.__json_read(only_event=True)
> >>          return self.__events
> >
> > Maybe this is better (untested):
> 
> I've tested it because that's how I implemented it first too :).
> However, I don't want to block until the QMP monitor sends the next
> event when there is already a received event pending.
> 
> The patch I posted polls for new events first, then only blocks if
> there are no events available.

Ok, pushed both patches to the QMP queue.

Thanks.