[libvirt] [PATCH 1/3] Domain events - primary implementation

[Daniel P. Berrange]

On Thu, Oct 09, 2008 at 08:33:14PM +0200, Stefan de Konink wrote:
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> Daniel P. Berrange schreef:
> >> +typedef enum {
> >> +      VIR_DOMAIN_EVENT_ADDED,
> >> +      VIR_DOMAIN_EVENT_REMOVED,
> >> +      VIR_DOMAIN_EVENT_STARTED,
> >> +      VIR_DOMAIN_EVENT_SUSPENDED,
> >> +      VIR_DOMAIN_EVENT_RESUMED,
> >> +      VIR_DOMAIN_EVENT_STOPPED,
> >> +      VIR_DOMAIN_EVENT_SAVED,
> >> +      VIR_DOMAIN_EVENT_RESTORED,
> >> +} virDomainEventType;
> 
> 
> Is it possible to get an *active* migration state event from the source.
> In xm list the name seems to change to migrating-.

These events are reflecting the result state of a VM. When a outgoing 
migration starts, it is still running as far as everyone should be
concerned - its supposed to be totally transparent. Once it completes
the results state is 'removed'. For an incoming migration, a VM starts
in the paused state until its finished migrating, at which point it is
running. So all the state changes associated with migration are tracked
already. 

I can see it might be desirable to be able to explicitly tell when an
outgoing migration starts & completes, and when an incoming migration
starts & completes. You'd likely want more info in the context fo the
migration event though - eg the destination host, and the source host.
So perhaps we should have an explicit migration event type you can
register for, separately from the domain execution lifecycle states. 

Daniel
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