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Re: [Qemu-devel] [PATCH v4 00/11] convert savevm to use qapi and introdu
From: |
Eric Blake |
Subject: |
Re: [Qemu-devel] [PATCH v4 00/11] convert savevm to use qapi and introduce qmp command |
Date: |
Wed, 10 Apr 2013 06:49:11 -0600 |
User-agent: |
Mozilla/5.0 (X11; Linux x86_64; rv:17.0) Gecko/20130402 Thunderbird/17.0.5 |
On 04/10/2013 06:40 AM, Luiz Capitulino wrote:
> On Wed, 10 Apr 2013 06:24:11 -0600
> Eric Blake <address@hidden> wrote:
>
>>> - If you want to overwrite an existing snapshot, you could specify
>>> the 'id' or the 'name' argument or both of them and also you will
>>> have to use the 'force' argument
>>
>> But the argument made in this thread is that QMP should _not_ have a
>> force argument. It should be a flat-out error in QMP to try to create a
>> snapshot with a conflicting name or tag; preferably with a distinct
>> error type. Higher-level apps (HMP savevm -f) would try to create; if
>> -f is not specified, the error is good enough; if -f is specified and
>> that particular error is returned, then HMP calls delete and then
>> re-tries the create. No 'force' argument needed at the QMP layer.
>
> To avoid adding a new error class, the HMP command could query for the
> snapshot name and delete it if it exists before creating the snapshot.
Atomic collision detection is nicer than having to pre-query - fewer QMP
calls in the common case. But you're right that none of the existing
ErrorClass categories fit the idea of "creation refused because name
would collide".
--
Eric Blake eblake redhat com +1-919-301-3266
Libvirt virtualization library http://libvirt.org
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- Re: [Qemu-devel] [PATCH v4 00/11] convert savevm to use qapi and introduce qmp command, Markus Armbruster, 2013/04/10
- Re: [Qemu-devel] [PATCH v4 00/11] convert savevm to use qapi and introduce qmp command, Pavel Hrdina, 2013/04/10
- Re: [Qemu-devel] [PATCH v4 00/11] convert savevm to use qapi and introduce qmp command, Eric Blake, 2013/04/10
- Re: [Qemu-devel] [PATCH v4 00/11] convert savevm to use qapi and introduce qmp command, Pavel Hrdina, 2013/04/10
- Re: [Qemu-devel] [PATCH v4 00/11] convert savevm to use qapi and introduce qmp command, Wenchao Xia, 2013/04/16
- Re: [Qemu-devel] [PATCH v4 00/11] convert savevm to use qapi and introduce qmp command, Markus Armbruster, 2013/04/11
- Re: [Qemu-devel] [PATCH v4 00/11] convert savevm to use qapi and introduce qmp command, Kevin Wolf, 2013/04/15
- Re: [Qemu-devel] [PATCH v4 00/11] convert savevm to use qapi and introduce qmp command, Eric Blake, 2013/04/15