Re: [Qemu-devel] [PATCH v3 06/15] blockjob: Add .txn_commit and .txn_abort transaction actions

[Fam Zheng]

On Tue, 07/14 09:35, Stefan Hajnoczi wrote:
> On Fri, Jul 10, 2015 at 11:46:43AM +0800, Fam Zheng wrote:
> > They will be called if the job is part of a transaction, after all jobs in a
> > transaction are completed or cancelled, before calling job->cb().
> > 
> > Signed-off-by: Fam Zheng <address@hidden>
> > ---
> >  include/block/blockjob.h | 12 ++++++++++++
> >  1 file changed, 12 insertions(+)
> > 
> > diff --git a/include/block/blockjob.h b/include/block/blockjob.h
> > index dd9d5e6..a7b7f66 100644
> > --- a/include/block/blockjob.h
> > +++ b/include/block/blockjob.h
> > @@ -50,6 +50,18 @@ typedef struct BlockJobDriver {
> >       * manually.
> >       */
> >      void (*complete)(BlockJob *job, Error **errp);
> > +
> > +    /**
> > +     * Optional callback for job types that can be in a transaction. Called
> > +     * when the transaction succeeds.
> > +     */
> > +    void (*txn_commit)(BlockJob *job);
> > +
> > +    /**
> > +     * Optional callback for job types that can be in a transaction. Call 
> > when
> > +     * the transaction fails.
> > +     */
> > +    void (*txn_abort)(BlockJob *job);
> >  } BlockJobDriver;
> 
> The semantics of transactions aren't fully documented.  My understanding
> is that you want:
> 1. either .txn_commit() or .txn_abort() to be called
> 2. after all jobs complete (due to success, error, or cancellation).
> 
> These two points are important for understanding these interfaces.

Yes, I'll add document these.

Fam