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Date: Wed, 13 Mar 2013 11:18:38 +0100
From: Kevin Wolf <kwolf@redhat.com>
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Subject: Re: [Qemu-devel] [PATCH V2 07/10] snapshot: qmp use new internal
 API for external snapshot transaction
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To: Wenchao Xia <xiawenc@linux.vnet.ibm.com>
Cc: aliguori@us.ibm.com, quintela@redhat.com, Stefan Hajnoczi <stefanha@gmail.com>, qemu-devel@nongnu.org, lcapitulino@redhat.com, pbonzini@redhat.com, dietmar@proxmox.com

Am 12.03.2013 um 09:30 hat Wenchao Xia geschrieben:
>   I redesigned the structure, Following is the fake code:
> 
> typedef struct BdrvActionOps {
>     /* check the request's validation, allocate p_opaque if needed */
>     int (*check)(BlockdevAction *action, void **p_opaque, Error **errp);
>     /* take the action */
>     int (*submit)(BlockdevAction *action, void *opaque, Error **errp);
>     /* update emulator */
>     int (*commit)(BlockdevAction *action, void *opaque, Error **errp);
>     /* cancel the action */
>     int (*rollback)(BlockdevAction *action, void *opaque, Error **errp);
> } BdrvActionOps;

Why do you need the split of prepare into check/submit?

If you have prepare/commit/abort, everybody will recognise this as the
standard transaction pattern because this is just how it's done.
Deviating from it needs a good justification in my opinion.

Kevin