Re: [Libguestfs] [PATCH] v2v: rhv-upload-plugin - improve wait logic after finalize (RHBZ#1680361)

Nir Soffer
2019-03-17T12:59:28Z

On Sun, Mar 17, 2019 at 2:07 PM Daniel Erez <derez@redhat.com> wrote:

> After invoking transfer_service.finalize, check operation
> status by examining ImageTransferPhase and DiskStatus.
> This is done instead of failing after a predefined timeout
> regardless the status.
>
> * not verified *
>
> Bug-Url: https://bugzilla.redhat.com/show_bug.cgi?id=1680361
> ---
>  v2v/rhv-upload-plugin.py | 26 +++++++++++++++++++++-----
>  1 file changed, 21 insertions(+), 5 deletions(-)
>
> diff --git a/v2v/rhv-upload-plugin.py b/v2v/rhv-upload-plugin.py
> index 2a950c5ed..873c11ce1 100644
> --- a/v2v/rhv-upload-plugin.py
> +++ b/v2v/rhv-upload-plugin.py
> @@ -523,14 +523,30 @@ def close(h):
>          # waiting for the transfer object to cease to exist, which
>          # falls through to the exception case and then we can
>          # continue.
> -        endt = time.time() + timeout
> +        start = time.time()
>          try:
>              while True:
>                  time.sleep(1)
> -                tmp = transfer_service.get()
> -                if time.time() > endt:
> -                    raise RuntimeError("timed out waiting for
transfer "
> -                                       "to finalize")
> +                transfer = transfer_service.get()
> +
> +                if transfer is None:
>

Are you sure this is possible? the original code assumed that we
fail with sdk.NotFoundError.


> +                    disk_service = h['disk_service']
> +                    disk = disk_service.get()
> +                    if disk.status == types.DiskStatus.OK:
> +                        continue
>

If the disk status is OK the upload was finished, so we should break, no?

If the disk status is LOCKED, we should continue. But in this case there is
no point to check the transfer again.

What if the finalize failed, and the disk was deleted? Do we get disk = None
or some exception?


> +
> +                if transfer.phase =>
types.ImageTransferPhase.FINISHED_SUCCESS:
> +                    debug("finalized after %s seconds",
time.time() -
> start)
> +                    break
> +
> +                if transfer.phase =>
types.ImageTransferPhase.FINALIZING_SUCCESS:
> +                    if time.time() > start + timeout:
> +                        raise RuntimeError("timed out waiting for
> transfer "
> +                                           "to finalize")
> +                    continue
> +
> +                raise RuntimeError("Unexpected transfer phase while
> finalizing "
> +                                   "upload %r" % transfer.phase)
>          except sdk.NotFoundError:
>              pass
>

Is this error possible? We need to add debug log here.

I think the logic should be:

   while True:
       wait
       get transfer
       if transfer does not exists (None or sdk.NotFoundErro) , break
       if transfer is finished, break (success)
       if transfer is finalizing:
           if timed out, fail
           continue
       fail with invalid transfer phase

   while True:
       wait
       get disk
       if disk does not exists (None or sdk.NotFoundErro), fail
       if disk is OK, break (success)
       if disk is locked:
           if timed out, fail
           continue
       fail with invalid disk status

This is little bit crazy that all user have to do this.

We need to change engine so transfer is kept in the database after it
finished for enough
time (1 hour?), so user can wait *only* for the transfer.

Nir