OVS agent: always send start flag during initial sync

In order to avoid inaccurate agent_boot_time setting,
this patch suggests to consider agent as "started" only
after completion of initial sync with server.

Change-Id: Icba05288889219e8a606c3809efd88b2c234bef3
Closes-Bug: #1799178

neutron/plugins/ml2/drivers/openvswitch/agent/ovs_neutron_agent.py

@@ -344,11 +344,16 @@ class OVSNeutronAgent(l2population_rpc.L2populationRpcCallBackTunnelMixin,
                 self.fullsync = True
 
             # we only want to update resource versions on startup
-            self.agent_state.pop('resource_versions', None)
-            if self.agent_state.pop('start_flag', None) and self.iter_num == 0:
+            if self.agent_state.pop('resource_versions', None):
                 # On initial start, we notify systemd after initialization
                 # is complete.
                 systemd.notify_once()
+
+            if self.iter_num > 0:
+                # agent is considered started after
+                # initial sync with server (iter 0) is done
+                self.agent_state.pop('start_flag', None)
+
         except Exception:
             LOG.exception("Failed reporting state!")
 

neutron/tests/unit/plugins/ml2/drivers/openvswitch/agent/test_ovs_neutron_agent.py

@@ -1144,7 +1144,8 @@ class TestOvsNeutronAgent(object):
                                          self.agent.agent_state, True)
             self.systemd_notify.assert_called_once_with()
             self.systemd_notify.reset_mock()
-            self.assertNotIn("start_flag", self.agent.agent_state)
+            # agent keeps sending "start_flag" while iter 0 not completed
+            self.assertIn("start_flag", self.agent.agent_state)
             self.assertEqual(
                 self.agent.agent_state["configurations"]["devices"],
                 self.agent.int_br_device_count