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>

2 files changed, 24 insertions, 1 deletions

diff --git a/examples/domain-events/events-c/event-test.c b/examples/domain-events/events-c/event-test.c
index c54778f7d..ef6e77a65 100644
--- a/examples/domain-events/events-c/event-test.c
+++ b/examples/domain-events/events-c/event-test.c
@@ -4,6 +4,7 @@
 #include <stdlib.h>
 #include <string.h>
 #include <signal.h>
+#include <inttypes.h>
 
 #include <libvirt/libvirt.h>
 #include <libvirt/virterror.h>
@@ -222,6 +223,17 @@ static int myDomainEventRTCChangeCallback(virConnectPtr conn ATTRIBUTE_UNUSED,
     return 0;
 }
 
+static int myDomainEventBalloonChangeCallback(virConnectPtr conn ATTRIBUTE_UNUSED,
+                                              virDomainPtr dom,
+                                              unsigned long long actual,
+                                              void *opaque ATTRIBUTE_UNUSED)
+{
+    printf("%s EVENT: Domain %s(%d) balloon change %" PRIuMAX "KB\n",
+           __func__, virDomainGetName(dom), virDomainGetID(dom), (uintmax_t)actual);
+
+    return 0;
+}
+
 static int myDomainEventWatchdogCallback(virConnectPtr conn ATTRIBUTE_UNUSED,
                                          virDomainPtr dom,
                                          int action,
@@ -391,6 +403,7 @@ int main(int argc, char **argv)
     int callback10ret = -1;
     int callback11ret = -1;
     int callback12ret = -1;
+    int callback13ret = -1;
     struct sigaction action_stop;
 
     memset(&action_stop, 0, sizeof(action_stop));
@@ -476,6 +489,11 @@ int main(int argc, char **argv)
                                                      VIR_DOMAIN_EVENT_ID_PMSUSPEND,
                                                      VIR_DOMAIN_EVENT_CALLBACK(myDomainEventPMSuspendCallback),
                                                      strdup("pmsuspend"), myFreeFunc);
+    callback13ret = virConnectDomainEventRegisterAny(dconn,
+                                                     NULL,
+                                                     VIR_DOMAIN_EVENT_ID_BALLOON_CHANGE,
+                                                     VIR_DOMAIN_EVENT_CALLBACK(myDomainEventBalloonChangeCallback),
+                                                     strdup("callback balloonchange"), myFreeFunc);
     if ((callback1ret != -1) &&
         (callback2ret != -1) &&
         (callback3ret != -1) &&
@@ -486,7 +504,8 @@ int main(int argc, char **argv)
         (callback9ret != -1) &&
         (callback10ret != -1) &&
         (callback11ret != -1) &&
-        (callback12ret != -1)) {
+        (callback12ret != -1) &&
+        (callback13ret != -1)) {
         if (virConnectSetKeepAlive(dconn, 5, 3) < 0) {
             virErrorPtr err = virGetLastError();
             fprintf(stderr, "Failed to start keepalive protocol: %s\n",
@@ -514,6 +533,7 @@ int main(int argc, char **argv)
         virConnectDomainEventDeregisterAny(dconn, callback10ret);
         virConnectDomainEventDeregisterAny(dconn, callback11ret);
         virConnectDomainEventDeregisterAny(dconn, callback12ret);
+        virConnectDomainEventDeregisterAny(dconn, callback13ret);
         if (callback8ret != -1)
             virConnectDomainEventDeregisterAny(dconn, callback8ret);
     }
diff --git a/examples/domain-events/events-python/event-test.py b/examples/domain-events/events-python/event-test.py
index 96dc2684f..137c31c88 100644
--- a/examples/domain-events/events-python/event-test.py
+++ b/examples/domain-events/events-python/event-test.py
@@ -483,6 +483,8 @@ def myDomainEventPMWakeupCallback(conn, dom, reason, opaque):
 def myDomainEventPMSuspendCallback(conn, dom, reason, opaque):
     print "myDomainEventPMSuspendCallback: Domain %s(%s) system pmsuspend" % (
             dom.name(), dom.ID())
+def myDomainEventBalloonChangeCallback(conn, dom, utcoffset, actual):
+    print "myDomainEventBalloonChangeCallback: Domain %s(%s) %d" % (dom.name(), dom.ID(), actual)
 def usage(out=sys.stderr):
     print >>out, "usage: "+os.path.basename(sys.argv[0])+" [-hdl] [uri]"
     print >>out, "   uri will default to qemu:///system"
@@ -544,6 +546,7 @@ def main():
     vc.domainEventRegisterAny(None, libvirt.VIR_DOMAIN_EVENT_ID_TRAY_CHANGE, myDomainEventTrayChangeCallback, None)
     vc.domainEventRegisterAny(None, libvirt.VIR_DOMAIN_EVENT_ID_PMWAKEUP, myDomainEventPMWakeupCallback, None)
     vc.domainEventRegisterAny(None, libvirt.VIR_DOMAIN_EVENT_ID_PMSUSPEND, myDomainEventPMSuspendCallback, None)
+    vc.domainEventRegisterAny(None, libvirt.VIR_DOMAIN_EVENT_ID_BALLOON_CHANGE, myDomainEventBalloonChangeCallback, None)
 
     vc.setKeepAlive(5, 3)