[libvirt] [PATCHv2 02/26] snapshot: better event when reverting qemu to paused snapshot
Daniel P. Berrange
berrange at redhat.com
Wed Aug 24 14:21:12 UTC 2011
On Mon, Aug 15, 2011 at 05:33:13PM -0600, Eric Blake wrote:
> When reverting a running domain to a paused snapshot, the event
> that fires should mention that the domain is suspended.
>
> * include/libvirt/libvirt.h.in
> (VIR_DOMAIN_EVENT_SUSPENDED_FROM_SNAPSHOT): New sub-event.
> * src/qemu/qemu_driver.c (qemuDomainRevertToSnapshot): Use it.
> ---
> include/libvirt/libvirt.h.in | 3 ++-
> src/qemu/qemu_driver.c | 10 ++++++----
> 2 files changed, 8 insertions(+), 5 deletions(-)
>
> diff --git a/include/libvirt/libvirt.h.in b/include/libvirt/libvirt.h.in
> index aa29fb6..a625479 100644
> --- a/include/libvirt/libvirt.h.in
> +++ b/include/libvirt/libvirt.h.in
> @@ -2010,7 +2010,7 @@ typedef enum {
> VIR_DOMAIN_EVENT_STARTED_BOOTED = 0, /* Normal startup from boot */
> VIR_DOMAIN_EVENT_STARTED_MIGRATED = 1, /* Incoming migration from another host */
> VIR_DOMAIN_EVENT_STARTED_RESTORED = 2, /* Restored from a state file */
> - VIR_DOMAIN_EVENT_STARTED_FROM_SNAPSHOT = 3, /* Restored from snapshot */
> + VIR_DOMAIN_EVENT_STARTED_FROM_SNAPSHOT = 3, /* Restored from running snapshot */
> } virDomainEventStartedDetailType;
>
> /**
> @@ -2023,6 +2023,7 @@ typedef enum {
> VIR_DOMAIN_EVENT_SUSPENDED_MIGRATED = 1, /* Suspended for offline migration */
> VIR_DOMAIN_EVENT_SUSPENDED_IOERROR = 2, /* Suspended due to a disk I/O error */
> VIR_DOMAIN_EVENT_SUSPENDED_WATCHDOG = 3, /* Suspended due to a watchdog firing */
> + VIR_DOMAIN_EVENT_SUSPENDED_FROM_SNAPSHOT = 4, /* Restored from paused snapshot */
> } virDomainEventSuspendedDetailType;
>
> /**
> diff --git a/src/qemu/qemu_driver.c b/src/qemu/qemu_driver.c
> index 421a98e..78d99f4 100644
> --- a/src/qemu/qemu_driver.c
> +++ b/src/qemu/qemu_driver.c
> @@ -8804,14 +8804,16 @@ static int qemuDomainRevertToSnapshot(virDomainSnapshotPtr snapshot,
> QEMU_ASYNC_JOB_NONE);
> if (rc < 0)
> goto endjob;
> + event = virDomainEventNewFromObj(vm,
> + VIR_DOMAIN_EVENT_SUSPENDED,
> + VIR_DOMAIN_EVENT_SUSPENDED_FROM_SNAPSHOT);
> } else {
> virDomainObjSetState(vm, VIR_DOMAIN_RUNNING,
> VIR_DOMAIN_RUNNING_FROM_SNAPSHOT);
> + event = virDomainEventNewFromObj(vm,
> + VIR_DOMAIN_EVENT_STARTED,
> + VIR_DOMAIN_EVENT_STARTED_FROM_SNAPSHOT);
> }
> -
> - event = virDomainEventNewFromObj(vm,
> - VIR_DOMAIN_EVENT_STARTED,
> - VIR_DOMAIN_EVENT_STARTED_FROM_SNAPSHOT);
> } else {
This isn't so nice. The lifecycle model for VMs is
shutoff <----> running <------>paused
This change creates a direct transition from shutoff to paused, missing
out the running state, which will break any apps which are just looking
to find out when guests stop/start and don't care about pause/resume.
Also
virsh start --paused $GUEST
will only emit a 'VIR_DOMAIN_EVENT_STARTED', so the current beahviour for
reverting to a paused snapshot matches that.
Arguably we could *also* emit an VIR_DOMAIN_EVENT_SUSPENDED, immediately
*after* the VIR_DOMAIN_EVENT_STARTED, in both cases though.
Daniel
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