Re: [Qemu-devel] [RFC PATCH V2 2/5] qapi: add event helper functions

[Wenchao Xia]

于 2014/1/7 6:23, Luiz Capitulino 写道:
> On Fri,  3 Jan 2014 07:10:31 +0800
> Wenchao Xia <address@hidden> wrote:
>
> > This file hold some functions that do not need to be generated.
> >
> > Signed-off-by: Wenchao Xia <address@hidden>
> > ---
> >   include/qapi/qmp-event.h |   22 ++++++++++++++++++
> >   qapi/Makefile.objs       |    1 +
> >   qapi/qmp-event.c         |   56 ++++++++++++++++++++++++++++++++++++++++++++++
> >   3 files changed, 79 insertions(+), 0 deletions(-)
> >   create mode 100644 include/qapi/qmp-event.h
> >   create mode 100644 qapi/qmp-event.c
> >
> > diff --git a/include/qapi/qmp-event.h b/include/qapi/qmp-event.h
> > new file mode 100644
> > index 0000000..2baf093
> > --- /dev/null
> > +++ b/include/qapi/qmp-event.h
> > @@ -0,0 +1,22 @@
> > +/*
> > + * QMP Event related
> > + *
> > + * Copyright IBM, Corp. 2014
> > + *
> > + * Authors:
> > + *  Wenchao Xia   <address@hidden>
> > + *
> > + * This work is licensed under the terms of the GNU GPLv2+ or later.
> > + * See the COPYING.LIB file in the top-level directory.
> > + *
> > + */
> > +
> > +#ifndef QMP_EVENT_H
> > +#define QMP_EVENT_H
> > +
> > +#include "qapi/error.h"
> > +#include "qapi/qmp/qdict.h"
> > +
> > +QDict *qmp_event_build_dict(const char *event_name);
> > +
> > +#endif
> > diff --git a/qapi/Makefile.objs b/qapi/Makefile.objs
> > index 1f9c973..d14b769 100644
> > --- a/qapi/Makefile.objs
> > +++ b/qapi/Makefile.objs
> > @@ -3,3 +3,4 @@ util-obj-y += qmp-output-visitor.o qmp-registry.o qmp-dispatch.o
> >   util-obj-y += string-input-visitor.o string-output-visitor.o
> >
> >   util-obj-y += opts-visitor.o
> > +util-obj-y += qmp-event.o
> > diff --git a/qapi/qmp-event.c b/qapi/qmp-event.c
> > new file mode 100644
> > index 0000000..dc81ec2
> > --- /dev/null
> > +++ b/qapi/qmp-event.c
> > @@ -0,0 +1,56 @@
> > +/*
> > + * QMP Event related
> > + *
> > + * Copyright IBM, Corp. 2014
> > + *
> > + * Authors:
> > + *  Wenchao Xia   <address@hidden>
> > + *
> > + * This work is licensed under the terms of the GNU GPLv2+ or later.
> > + * See the COPYING.LIB file in the top-level directory.
> > + *
> > + */
> > +
> > +#include <inttypes.h>
> > +
> > +#include "qemu-common.h"
> > +#include "qapi/qmp-event.h"
> > +#include "qapi/qmp/qstring.h"
> > +#include "qapi/qmp/qjson.h"
> > +
> > +#ifdef _WIN32
> > +#include "sysemu/os-win32.h"
> > +#endif
> > +
> > +#ifdef CONFIG_POSIX
> > +#include "sysemu/os-posix.h"
> > +#endif
> > +
> > +static void timestamp_put(QDict *qdict)
> > +{
> > +    int err;
> > +    QObject *obj;
> > +    qemu_timeval tv;
> > +
> > +    err = qemu_gettimeofday(&tv);
> > +    if (err < 0) {
> > +        return;
> > +    }
>
> Hmm, I see this has always existed (and I guess I did it myself), but it's
> not quite right. Sending an event w/o time info wouldn't be complaint to
> the protocol spec. It's a good idea to fix this now. We have three options:
>
>   1. abort()
>
>   2. Skip sending the event altogether
>
>   3. Add a bogus time value (say seconds=0 and microseconds=0)
>
> I don't know what's best, but I guess I'd do item 3. Although I wonder
> if zero is any better then no info at all (it's certainly complaint, but
> not a valid info). Maybe skip the event then?

  I think user want a way, to know error happens. If it is
skepted, then we should report it in stderr or a special message in
monitor. In my opinion, sending an event would be the easist way.
We can set time to zero and doc "timestamp == 0 means failure in
getting host time", and this avoid impacting existing user who always
seeking key "timestamp".

> > +
> > +    obj = qobject_from_jsonf("{ 'seconds': %" PRId64 ", "
> > +                                "'microseconds': %" PRId64 " }",
> > +                                (int64_t) tv.tv_sec, (int64_t) tv.tv_usec);
> > +    qdict_put_obj(qdict, "timestamp", obj);
> > +}
> > +
> > +/*
> > + * Build a QDict, then fill event name and time stamp, caller should free the
> > + * QDict after usage.
> > + */
> > +QDict *qmp_event_build_dict(const char *event_name)
> > +{
> > +    QDict *dict = qdict_new();
> > +    qdict_put(dict, "event", qstring_from_str(event_name));
> > +    timestamp_put(dict);
> > +    return dict;
> > +}