Re: [libvirt] [PATCH] virDomainShutdown*: Describe blocking behaviour
On 30.03.2015 22:38, Eric Blake wrote:
On 03/30/2015 06:07 AM, Michal Privoznik wrote:
> The description to both virDomainShutdown() and
> virDomainShutdownFlags() is quite misleading when it comes to
> blocking behaviour of these two APIs. Firstly, we support many
> shutdown methods, from signalizing an ACPI event, through sending
> a signal to guest agent assisted shutdown. Some of these methods
> make the API return immediately, while others block the API until
> domain is actually shut of. And since virDomainShutdown() is
s/of/off/
> equivalent to calling virDomainShutdownFlags(0), it's up to each
> driver which methods to try. So the bare virDomainShutdown() may
> block or may return immediately at the same time. I know, it's
> confusing, but at least let users know.
>
> Signed-off-by: Michal Privoznik <mprivozn(a)redhat.com>
> ---
> src/libvirt-domain.c | 13 +++++++++----
> 1 file changed, 9 insertions(+), 4 deletions(-)
>
I don't think this is the right approach. It is okay to block for a
small finite amount of time, but if the guest agent really is something
that can hang, we should fix that code to return without waiting for the
agent response.
The problem is, we can tell if the shutdown qemu-ga command succeeded
only when we see the SHUTDOWN event on the domain monitor. The other
option is to treat it like we're treating ACPI mode of the API: just
send the request and report if the sending succeeded. Don't wait until
domain actually shuts down. I can provide a patch.
Michal