Re: [Qemu-devel] [PATCH V11 09/17] qmp: add interface query-snapshots

[Markus Armbruster]

Wenchao Xia <address@hidden> writes:

>>>   # Statistics of a virtual block device or a block backing device.
>>> diff --git a/qmp-commands.hx b/qmp-commands.hx
>>> index 1e0e11e..6b20684 100644
>>> --- a/qmp-commands.hx
>>> +++ b/qmp-commands.hx
>>> @@ -1765,6 +1765,61 @@ EQMP
>>>       },
>>>   
>>>   SQMP
>>> +query-snapshots
>>> +---------------
>>> +
>>> +Show the internal consistent snapshot information
>>> +
>>> +Each snapshot is represented by a json-object. The returned value
>>> +is a json-array of all snapshots
>>> +
>>> +Each json-object contain the following:
>>> +
>>> +- "id": unique snapshot id (json-string)
>>> +- "name": internal snapshot name (json-string)
>>> +- "vm-state-size": size of the VM state in bytes (json-int)
>>> +- "date-sec": UTC date of the snapshot in seconds (json-int)
>>> +- "date-nsec": fractional part in nanoseconds to be used with
>>> +               date-sec(json-int)
>>> +- "vm-clock-sec": VM clock relative to boot in seconds (json-int)
>>> +- "vm-clock-nsec": fractional part in nanoseconds to be used with
>>> +                   vm-clock-sec (json-int)
>>> +
>>> +Example:
>>> +
>>> +-> { "execute": "query-snapshots" }
>>> +<- {
>>> +      "return":[
>>> +         {
>>> +            "id": "1",
>>> +            "name": "snapshot1",
>>> +            "vm-state-size": 0,
>>> +            "date-sec": 10000200,
>>> +            "date-nsec": 12,
>>> +            "vm-clock-sec": 206,
>>> +            "vm-clock-nsec": 30
>> 
>> Not your patch's fault, but here goes anyway: I dislike this
>> representation of time.
>> 
>> QMP has time in seconds, milliseconds, nanoseconds, (seconds,
>> milliseconds) and (seconds, nanoseconds).  There has been no adult
>> supervision, obviously (I may say that, because it's as much my fault as
>> it's anybody else's).
>> 
>> The sanest one by far is nanoseconds.  Good for 2^63 of them.  Since pi
>> seconds is a nanocentury, good for 2^63 / (pi * 1e9) centuries, which
>> should be safely beyond your retirement age.
>> 
>   OK, will insert a patch before removing "vm-clock-sec".

Before you do that, let's get Luiz's blessing.

>                                                           Have one
> question: how to declare uint64_t in qmp-schema.json?

You can't.  All we got is 'int'.  The implementation restricts 'int'
values to 64 bits signed.  Plenty of range for this purpose.

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