[libvirt] [PATCH 11/13] virsh: Refactor block job waiting in cmdBlockPull

Eric Blake eblake at redhat.com
Mon Jul 20 21:47:25 UTC 2015

On 07/15/2015 10:34 AM, Peter Krempa wrote:
> Introduce helper function that will provide logic for waiting for block
> job completion so the 3 open coded places can be unified and improved.
> This patch introduces the whole logic and uses it to fix
> cmdBlockJobPull. The vshBlockJobWait funtion provides common logic for


> block job waiting that should be robust enough to work across all
> previous versions of libvirt. Since virsh allows to pass user-provided

s/allows to pass/allows passing/

> strings as paths of block devices we can't reliably use block job events
> for detection of block job states so the function contains a great deal
> of fallback logic.
> ---
>  tools/virsh-domain.c | 326 ++++++++++++++++++++++++++++++++++++++-------------
>  1 file changed, 244 insertions(+), 82 deletions(-)

> +/**
> + * vshBlockJobWait:
> + * @data: private data initialized by vshBlockJobWaitInit
> + *
> + * Waits for the block job to complete. This fucntion prefers to get an event


> +        /* for two-phase jobs we will try to wait in the synchronized phase
> +         * for event arival since 100% completion doesn't necessarily mean that


> +         * the block job has finished and can be terminated with success */
> +        if (info.end == info.cur && --retries == 0) {

As I said in the other patch, if info.end == info.cur and they are
non-zero, that SHOULD be equivalent to the job being complete (a
blockpull finishing, or a two-phase job transitioning to synchronized);
where it gets tricky is if the two are equal but zero (as some jobs can
validly have info.end == 0, but most jobs just see info.end as 0 before
getting into the main loop of the job).  But it looks like you are doing
okay here.

Eric Blake   eblake redhat com    +1-919-301-3266
Libvirt virtualization library http://libvirt.org

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