Re: [Qemu-devel] [PATCH 7/7] block: dump to monitor for bdrv_snapshot_dump() and bdrv_image_info_dump()

[Wenchao Xia]

于 2013-5-20 10:39, Wenchao Xia 写道:
> 于 2013-5-17 20:30, Luiz Capitulino 写道:
>> On Fri, 17 May 2013 11:30:31 +0800
>> Wenchao Xia <address@hidden> wrote:
>>
>>> 于 2013-5-16 20:17, Luiz Capitulino 写道:
>>>> On Thu, 16 May 2013 10:22:09 +0800
>>>> Wenchao Xia <address@hidden> wrote:
>>>>
>>>>> 于 2013-5-15 20:28, Luiz Capitulino 写道:
>>>>>> On Wed, 15 May 2013 10:10:37 +0800
>>>>>> Wenchao Xia <address@hidden> wrote:
>>>>>>
>>>>>>> 于 2013-5-6 21:22, Luiz Capitulino 写道:
>>>>>>>> On Mon, 06 May 2013 10:09:43 +0800
>>>>>>>> Wenchao Xia <address@hidden> wrote:
>>>>>>>>
>>>>>>>>> 于 2013-5-3 10:51, Wenchao Xia 写道:
>>>>>>>>>> 于 2013-5-2 20:02, Luiz Capitulino 写道:
>>>>>>>>>>> On Thu, 02 May 2013 10:05:08 +0800
>>>>>>>>>>> Wenchao Xia <address@hidden> wrote:
>>>>>>>>>>>
>>>>>>>>>>>> 于 2013-4-30 3:05, Luiz Capitulino 写道:
>>>>>>>>>>>>> On Fri, 26 Apr 2013 16:46:57 +0200
>>>>>>>>>>>>> Stefan Hajnoczi <address@hidden> wrote:
>>>>>>>>>>>>>
>>>>>>>>>>>>>> On Fri, Apr 26, 2013 at 05:31:15PM +0800, Wenchao Xia wrote:
>>>>>>>>>>>>>>> @@ -2586,10 +2585,12 @@ void do_info_snapshots(Monitor 
>>>>>>>>>>>>>>> *mon, const
>>>>>>>>>>>>>>> QDict *qdict)
>>>>>>>>>>>>>>>            }
>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>            if (total > 0) {
>>>>>>>>>>>>>>> -        monitor_printf(mon, "%s\n", bdrv_snapshot_dump(buf,
>>>>>>>>>>>>>>> sizeof(buf), NULL));
>>>>>>>>>>>>>>> +        bdrv_snapshot_dump(NULL);
>>>>>>>>>>>>>>> +        monitor_printf(mon, "\n");
>>>>>>>>>>>>>>
>>>>>>>>>>>>>> Luiz: any issue with mixing monitor_printf(mon) and
>>>>>>>>>>>>>> monitor_vprintf(cur_mon) calls?  I guess there was a 
>>>>>>>>>>>>>> reason for
>>>>>>>>>>>>>> explicitly passing mon instead of relying on cur_mon.
>>>>>>>>>>>>>
>>>>>>>>>>>>> where are they being mixed?
>>>>>>>>>>>>>
>>>>>>>>>>>>         bdrv_snapshot_dump() used a global variable 
>>>>>>>>>>>> "cur_mon" inside,
>>>>>>>>>>>> instead
>>>>>>>>>>>> of let caller pass in a explicit montior* "mon", I guess 
>>>>>>>>>>>> that is the
>>>>>>>>>>>> question.
>>>>>>>>>>>
>>>>>>>>>>> I'd have to see the code to tell, but yes, what Stefan 
>>>>>>>>>>> described is the
>>>>>>>>>>> best practice for the Monitor.
>>>>>>>>>>>
>>>>>>>>>>        I think this would not be a problem until qemu wants 
>>>>>>>>>> more than one
>>>>>>>>>> human monitor console, and then we may require a data 
>>>>>>>>>> structure to tell
>>>>>>>>>> where to output the string: stdout, *mon, or even stderr, and
>>>>>>>>>> error_printf() also need to be changed.
>>>>>>>>>>
>>>>>>>>>        Luiz, what is your idea? I'd like to respin v2 if no 
>>>>>>>>> issues for it.
>>>>>>>>
>>>>>>>> As I said before, I'd have to see the code to tell. But 
>>>>>>>> answering your comment,
>>>>>>>> the code does support multiple monitors.
>>>>>>>>
>>>>>>> Hi Luiz,
>>>>>>>       Sorry to ask again, do you think method above is OK now, 
>>>>>>> waiting for
>>>>>>> your confirm.
>>>>>>
>>>>>> Can you point me to the code in question?
>>>>>>
>>>>> Sure, it is
>>>>>
>>>>> +
>>>>> +/*
>>>>> + * Print to current monitor if we have one, else to stdout. It is
>>>>> similar with
>>>>> + * error_printf().
>>>>> + * TODO just like error_vprintf()
>>>>> + */
>>>>> +void message_printf(const char *fmt, ...)
>>>>> +{
>>>>> +    va_list ap;
>>>>> +
>>>>> +    va_start(ap, fmt);
>>>>> +    if (cur_mon) {
>>>>> +        monitor_vprintf(cur_mon, fmt, ap);
>>>>> +    } else {
>>>>> +        vfprintf(stdout, fmt, ap);
>>>>> +    }
>>>>> +    va_end(ap);
>>>>> +}
>>>>>
>>>>>      This function used global variable cur_mon instead of input 
>>>>> parameter,
>>>>> similar to error_printf().
>>>>
>>>> Why do you need it? Why can't you you use error_printf() for example?
>>>>
>>>     error_printf() will print out to stderr in qemu-img, but stdout is
>>> wanted for those dump info function.
>>
>> You can refactor the code so that you can pass a FILE *stream argument to
>> error_vprintf() and maybe add error_printf_stream()?
>>
>    The name is a bit confusing, maybe qemu_printf()? Another problem is,
> monitor have a buf[] instead of a FILE*, I think it need a structure
> include those:
> 
> typdef enum QemuOutputType {
>      QEMU_OUTPUT_TYPE_STREAM,
>      QEMU_OUTPUT_TYPE_MONITOR,
> } QemuOutputType;
> 
> typedef struct QemuOutput {
>      QemuOutputType type;
>      union {
>          FILE *file;
>          Monitor *mon;
>      };
> }
> 
>    It may brings some inconvienience to caller, but this is what I can
> think out now.
> 
  Luiz, I am going to respin V2 as above, can I have you confirm on it?

-- 
Best Regards

Wenchao Xia