Libvirt error handling.

Only log error in case of error.

ccnode/hypervisor/__init__.py

@@ -222,6 +222,8 @@ class Hypervisor(object):
         self.name = name
         self.type = u'kvm'
 
+        # register libvirt error handler
+        libvirt.registerErrorHandler(self.vir_error_cb, None)
         # libvirt event loop abstraction
         self.vir_event_loop = VirEventLoop(self.handler.main.evloop)
         # This tells libvirt what event loop implementation it
@@ -259,9 +261,27 @@ class Hypervisor(object):
 
     def stop(self):
         self.vir_event_loop.stop()
-        self.vir_con.close()
+        # unregister callback
+        try:
+            self.vir_con.domainEventDeregister(self.vir_cb)
+        except libvirt.libvirtError:
+            # in case the libvirt connection is broken, it will raise the error
+            pass
+        ret = self.vir_con.close()
+        logger.debug('Libvirt still handling %s ref connections', ret)
         # TODO delet objects
 
+    def vir_error_cb(self, ctxt, err):
+        """Libvirt error callback.
+
+        See http://libvirt.org/errors.html for more informations.
+
+        :param ctxt: arbitrary context data (not needed because context is
+            givent by self
+        :param err: libvirt error code
+        """
+        logger.error('Libvirt error %s', err)
+
     def vir_cb(self, conn, dom, event, detail, opaque):
         """Callback for libvirt event loop."""
         logger.debug('Received event %s on domain %s, detail %s', event,