Re: [Qemu-devel] [PATCH V4 10/16] qmp event: Add COLO_EXIT event to notify users while exited COLO

[Zhang Chen]

On Sat, Feb 3, 2018 at 3:49 PM, Markus Armbruster <address@hidden> wrote:

> Zhang Chen <address@hidden> writes:
>
> > From: zhanghailiang <address@hidden>
> >
> > If some errors happen during VM's COLO FT stage, it's important to
> > notify the users of this event. Together with 'x-colo-lost-heartbeat',
> > Users can intervene in COLO's failover work immediately.
> > If users don't want to get involved in COLO's failover verdict,
> > it is still necessary to notify users that we exited COLO mode.
> >
> > Signed-off-by: zhanghailiang <address@hidden>
> > Signed-off-by: Li Zhijian <address@hidden>
> > Signed-off-by: Zhang Chen <address@hidden>
> > Reviewed-by: Eric Blake <address@hidden>
> [...]
> > diff --git a/qapi/migration.json b/qapi/migration.json
> > index 70e7b67..6fc95b7 100644
> > --- a/qapi/migration.json
> > +++ b/qapi/migration.json
> > @@ -869,6 +869,41 @@
> >    'data': [ 'none', 'require', 'active', 'completed', 'relaunch' ] }
> >
> >  ##
> > +# @COLO_EXIT:
> > +#
> > +# Emitted when VM finishes COLO mode due to some errors happening or
> > +# at the request of users.
> > +#
> > +# @mode: which COLO mode the VM was in when it exited.
> > +#
> > +# @reason: describes the reason for the COLO exit.
> > +#
> > +# Since: 2.12
> > +#
> > +# Example:
> > +#
> > +# <- { "timestamp": {"seconds": 2032141960, "microseconds": 417172},
> > +#      "event": "COLO_EXIT", "data": {"mode": "primary", "reason":
> "request" } }
> > +#
> > +##
> > +{ 'event': 'COLO_EXIT',
> > +  'data': {'mode': 'COLOMode', 'reason': 'COLOExitReason' } }
>
> Standard question when I see a new event: is there a way to poll for the
> event's information?  If not, why don't we need one?
>
>
Your means is we'd better print the information to a log file or something
like that for all qemu events?
CC  Eric Blake <address@hidden>
any idea about this?

Thanks
Zhang Chen


> Remember, management applications might miss events when they lose the
> connection and have to reconnect, say because the management application
> needs to be restarted.
>
> > +
> > +##
> > +# @COLOExitReason:
> > +#
> > +# The reason for a COLO exit
> > +#
> > +# @request: COLO exit is due to an external request
> > +#
> > +# @error: COLO exit is due to an internal error
> > +#
> > +# Since: 2.12
> > +##
> > +{ 'enum': 'COLOExitReason',
> > +  'data': [ 'request', 'error' ] }
> > +
> > +##
> >  # @x-colo-lost-heartbeat:
> >  #
> >  # Tell qemu that heartbeat is lost, request it to do takeover
> procedures.
>