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Re: [Qemu-devel] [PATCH V11 09/17] qmp: add interface query-snapshots
From: |
Eric Blake |
Subject: |
Re: [Qemu-devel] [PATCH V11 09/17] qmp: add interface query-snapshots |
Date: |
Thu, 11 Apr 2013 07:08:41 -0600 |
User-agent: |
Mozilla/5.0 (X11; Linux x86_64; rv:17.0) Gecko/20130402 Thunderbird/17.0.5 |
On 04/11/2013 06:44 AM, Luiz Capitulino wrote:
>>>>> +-> { "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,
> Are you saying you're going to drop vm-clock-sec?
>
>> Before you do that, let's get Luiz's blessing.
>
> Fine with me if I got it right.
Problem. Let's go back to the original definition that we are talking
about modifying:
+#
+# Since: 1.5
+##
+{ 'command': 'query-snapshots',
+ 'returns': ['SnapshotInfo'] }
+
Now let's look for that type:
# @vm-clock-sec: VM clock relative to boot in seconds
#
# @vm-clock-nsec: fractional part in nano seconds to be used with
vm-clock-sec
#
# Since: 1.3
#
##
{ 'type': 'SnapshotInfo',
'data': { 'id': 'str', 'name': 'str', 'vm-state-size': 'int',
'date-sec': 'int', 'date-nsec': 'int',
'vm-clock-sec': 'int', 'vm-clock-nsec': 'int' } }
And that type is already used in 'ImageInfo'.
In other words, we're stuck. We've already cemented the mistake. You
_can't_ drop vm-clock-sec, without breaking the behavior of management
apps written against the 1.3 interface when dealing with ImageInfo. If
you want to avoid a (sec/nsec) pair, you would have to invent a new type
instead of reusing the already-existing SnapshotInfo.
Hmm, as I typed that, I did another search of qemu-schema.json - we have
the type 'ImageInfo' defined, but none of the existing 'command's ever
call out the use of that type. Is it a type we are only using
internally to date, and where this is the first QMP command that would
actually expose SnapshotInfo or ImageInfo to a management app? Then
maybe we _CAN_ modify SnapshotInfo, clean up all the internal code, and
provide a saner type for the first time that QMP can actually use it.
--
Eric Blake eblake redhat com +1-919-301-3266
Libvirt virtualization library http://libvirt.org
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- [Qemu-devel] [PATCH V11 06/17] block: add check for VM snapshot in bdrv_query_snapshot_info_list(), (continued)
- [Qemu-devel] [PATCH V11 06/17] block: add check for VM snapshot in bdrv_query_snapshot_info_list(), Wenchao Xia, 2013/04/02
- [Qemu-devel] [PATCH V11 08/17] block: move qmp_query_block() and bdrv_query_info() to block/qapi.c, Wenchao Xia, 2013/04/02
- [Qemu-devel] [PATCH V11 09/17] qmp: add interface query-snapshots, Wenchao Xia, 2013/04/02
- Re: [Qemu-devel] [PATCH V11 09/17] qmp: add interface query-snapshots, Stefan Hajnoczi, 2013/04/08
- Re: [Qemu-devel] [PATCH V11 09/17] qmp: add interface query-snapshots, Markus Armbruster, 2013/04/10
- Re: [Qemu-devel] [PATCH V11 09/17] qmp: add interface query-snapshots, Wenchao Xia, 2013/04/11
- Re: [Qemu-devel] [PATCH V11 09/17] qmp: add interface query-snapshots, Markus Armbruster, 2013/04/11
- Re: [Qemu-devel] [PATCH V11 09/17] qmp: add interface query-snapshots, Luiz Capitulino, 2013/04/11
- Re: [Qemu-devel] [PATCH V11 09/17] qmp: add interface query-snapshots,
Eric Blake <=
- Re: [Qemu-devel] [PATCH V11 09/17] qmp: add interface query-snapshots, Luiz Capitulino, 2013/04/11
- Re: [Qemu-devel] [PATCH V11 09/17] qmp: add interface query-snapshots, Wenchao Xia, 2013/04/11
- Re: [Qemu-devel] [PATCH V11 09/17] qmp: add interface query-snapshots, Eric Blake, 2013/04/11
- Re: [Qemu-devel] [PATCH V11 09/17] qmp: add interface query-snapshots, Wenchao Xia, 2013/04/12
- Re: [Qemu-devel] [PATCH V11 09/17] qmp: add interface query-snapshots, Markus Armbruster, 2013/04/12
[Qemu-devel] [PATCH V11 10/17] qmp: add recursive member in ImageInfo, Wenchao Xia, 2013/04/02
[Qemu-devel] [PATCH V11 07/17] block: add image info query function bdrv_query_image_info(), Wenchao Xia, 2013/04/02