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

[Wenchao Xia <xiawenc@linux.vnet.ibm.com>]

于 2014/1/7 6:23, Luiz Capitulino 写道:
> On Fri,  3 Jan 2014 07:10:31 +0800
> Wenchao Xia <xiawenc@linux.vnet.ibm.com> wrote:
>
>> This file hold some functions that do not need to be generated.
>>
>> Signed-off-by: Wenchao Xia <xiawenc@linux.vnet.ibm.com>
>> ---
>>   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   <xiawenc@linux.vnet.ibm.com>
>> + *
>> + * 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   <xiawenc@linux.vnet.ibm.com>
>> + *
>> + * 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;
>> +}
>