virtManager: object: domain: Check for guest agent

For qemu, only run the API if the VM has the qemu guest agent in the
XML. If it is present, wait for it to come online instead of
unconditionally retrying a number of times.

Reuse agent function agent_ready() from refresh_interface_addresses()
and refactor it into two methods of which get_agent() can be used to
check for agent presence and further work with the channel object.

Reviewed-by: Cole Robinson <crobinso@redhat.com>
Signed-off-by: Michael Weiser <michael.weiser@gmx.de>
Suggested-by: Cole Robinson <crobinso@redhat.com>

virtManager/object/domain.py

@@ -1054,15 +1054,28 @@ class vmmDomain(vmmLibvirtObject):
             log.debug("Creating snapshot flags=%s xml=\n%s", flags, xml)
         self._backend.snapshotCreateXML(xml, flags)
 
-    def refresh_interface_addresses(self, iface):
-        def agent_ready():
+    def _get_agent(self):
+        """
+        Return agent channel object if it is defined.
+        """
         for dev in self.xmlobj.devices.channel:
             if (dev.type == "unix" and
-                    dev.target_name == dev.CHANNEL_NAME_QEMUGA and
-                    dev.target_state == "connected"):
+                dev.target_name == dev.CHANNEL_NAME_QEMUGA):
+                return dev
+        return None
+
+    def _agent_ready(self):
+        """
+        Return connected state of an agent.
+        """
+        # we need to get a fresh agent channel object on each call so it
+        # reflects the current state
+        dev = self._get_agent()
+        if dev and dev.target_state == "connected":
             return True
         return False
 
+    def refresh_interface_addresses(self, iface):
         self._ip_cache = {"qemuga": {}, "arp": {}}
         if iface.type == "network":
             net = self.conn.get_net(iface.source)
@@ -1071,7 +1084,7 @@ class vmmDomain(vmmLibvirtObject):
         if not self.is_active():
             return
 
-        if agent_ready():
+        if self._agent_ready():
             self._ip_cache["qemuga"] = self._get_interface_addresses(
                 libvirt.VIR_DOMAIN_INTERFACE_ADDRESSES_SRC_AGENT)
 
@@ -1154,10 +1167,25 @@ class vmmDomain(vmmLibvirtObject):
         if not self.conn.is_qemu() and not self.conn.is_test():
             return
 
-        # retry an arbitrary number of times to give the agent some time to
-        # come back online after e.g. resuming the domain
-        attempt = 1
-        while attempt < 5:
+        if self.conn.is_qemu():
+            # For qemu, only run the API if the VM has the qemu guest agent in
+            # the XML.
+            if not self._get_agent():
+                return
+
+            # wait for agent to come online
+            maxwait = 5
+            sleep = 0.5
+            for _ in range(0, int(maxwait / sleep)):
+                if self._agent_ready():
+                    break
+                log.debug("Waiting for qemu guest agent to come online...")
+                time.sleep(sleep)
+            else:
+                if not self._agent_ready():
+                    log.debug("Giving up on qemu guest agent for time sync")
+                    return
+
         t = time.time()
         seconds = int(t)
         nseconds = int((t - seconds) * 10 ** 9)
@@ -1168,8 +1196,6 @@ class vmmDomain(vmmLibvirtObject):
         except Exception as e:
             log.debug("Failed to set time: %s", e)
 
-            attempt += 1
-
 
     ########################
     # XML Parsing routines #