Define public API for receiving guest memory balloon events

When the guest changes its memory balloon applications may want
to know what the new value is, without having to periodically
poll on XML / domain info. Introduce a "balloon change" event
to let apps see this

* include/libvirt/libvirt.h.in: Define the
  virConnectDomainEventBalloonChangeCallback callback
  and VIR_DOMAIN_EVENT_ID_BALLOON_CHANGE constant
* python/libvirt-override-virConnect.py,
  python/libvirt-override.c: Wire up helpers for new event
* daemon/remote.c: Helper for serializing balloon event
* examples/domain-events/events-c/event-test.c,
  examples/domain-events/events-python/event-test.py: Add
  example of balloon event usage
* src/conf/domain_event.c, src/conf/domain_event.h: Handling
  of balloon events
* src/remote/remote_driver.c: Add handler of balloon events
* src/remote/remote_protocol.x: Define wire protocol for
  balloon events
* src/remote_protocol-structs: Likewise.
Signed-off-by: Daniel P. Berrange <berrange@redhat.com>

1 files changed, 17 insertions, 0 deletions

diff --git a/include/libvirt/libvirt.h.in b/include/libvirt/libvirt.h.in
index 6e8d5dd43..e34438cda 100644
--- a/include/libvirt/libvirt.h.in
+++ b/include/libvirt/libvirt.h.in
@@ -3861,6 +3861,22 @@ typedef void (*virConnectDomainEventPMSuspendCallback)(virConnectPtr conn,
                                                        int reason,
                                                        void *opaque);
 
+
+/**
+ * virConnectDomainEventBalloonChangeCallback:
+ * @conn: connection object
+ * @dom: domain on which the event occurred
+ * @actual: the new balloon level measured in kibibytes(blocks of 1024 bytes)
+ * @opaque: application specified data
+ *
+ * The callback signature to use when registering for an event of type
+ * VIR_DOMAIN_EVENT_ID_BALLOON_CHANGE with virConnectDomainEventRegisterAny()
+ */
+typedef void (*virConnectDomainEventBalloonChangeCallback)(virConnectPtr conn,
+                                                           virDomainPtr dom,
+                                                           unsigned long long actual,
+                                                           void *opaque);
+
 /**
  * VIR_DOMAIN_EVENT_CALLBACK:
  *
@@ -3884,6 +3900,7 @@ typedef enum {
     VIR_DOMAIN_EVENT_ID_TRAY_CHANGE = 10,    /* virConnectDomainEventTrayChangeCallback */
     VIR_DOMAIN_EVENT_ID_PMWAKEUP = 11,       /* virConnectDomainEventPMWakeupCallback */
     VIR_DOMAIN_EVENT_ID_PMSUSPEND = 12,      /* virConnectDomainEventPMSuspendCallback */
+    VIR_DOMAIN_EVENT_ID_BALLOON_CHANGE = 13, /* virConnectDomainEventBalloonChangeCallback */
 
 #ifdef VIR_ENUM_SENTINELS
     /*