[libvirt] [PATCH 03/20] virConnect(Un)RegisterCloseCallback: Throw an error in case the API is not supported

[Nikolay Shirokovskiy]

On 08.03.2018 15:20, Marc Hartmayer wrote:
> Report an error in case the driver does not support
> connect(Un)registerCloseCallback. The commit 'close callback: move it
> to driver' (88f09b75eb99) moved the responsibility for the close
> callback to the driver. But if the driver doesn't support the
> connectRegisterCloseCallback API this function does nothing, even no
> unsupported error report. The only case where an error is reported is
> when the API is supported but the call fails. The same behavior
> applies to virConnectUnregisterCloseCallback.
> 
> This behavior is not intended as there are many use cases of this API
> where the state of for example allocations depends on the result of
> these functions.
> 
> To keep the behavior of virsh as before it must silently ignore
> unsupported error for virConnectRegisterCloseCallback. For the remote
> driver this change wouldn't be needed, but for the byhve driver, for
> example. Otherwise the user would see the error message that virsh was
> unable to register a disconnect callback.
> 
> Signed-off-by: Marc Hartmayer <mhartmay at linux.vnet.ibm.com>
> Reviewed-by: Boris Fiuczynski <fiuczy at linux.vnet.ibm.com>
> ---
>  src/libvirt-host.c | 24 ++++++++++++++----------
>  tools/virsh.c      | 11 +++++++++--
>  2 files changed, 23 insertions(+), 12 deletions(-)
> 

We can't change public API. As to patch 18 I suggest either to:

- don't refcount client object, this works though it is dangerous. Or
- check if driver supports VIR_DRV_FEATURE_REMOTE_CLOSE_CALLBACK and throw
  an error if it does not (looks better to me)

Nikolay