SimpleInterfaceMonitor: get rid of self.data_received flag

It's not used anywhere outside tests, and there are better ways to
wait for updates.

The flag was once used to influence the state of activeness for the
monitor, but not anymore [1].

This cleanup also allows us to remove custom _read_stdout from the
monitor and reuse the one inherited from AsyncProcess. Meaning, we
also can safely get rid of another pile of duplicate tests.

[1]: I05faeddd061ab45af51c044a10462c3a57593d4d

Change-Id: I612d492c8f65a70e18f782a5e4d055de5f7948ef

neutron/agent/linux/ovsdb_monitor.py

@@ -60,7 +60,6 @@ class SimpleInterfaceMonitor(OvsdbMonitor):
             format='json',
             respawn_interval=respawn_interval,
         )
-        self.data_received = False
         self.new_events = {'added': [], 'removed': []}
 
     @property
@@ -109,13 +108,3 @@ class SimpleInterfaceMonitor(OvsdbMonitor):
             with eventlet.timeout.Timeout(timeout):
                 while not self.is_active():
                     eventlet.sleep()
-
-    def _kill(self, *args, **kwargs):
-        self.data_received = False
-        super(SimpleInterfaceMonitor, self)._kill(*args, **kwargs)
-
-    def _read_stdout(self):
-        data = super(SimpleInterfaceMonitor, self)._read_stdout()
-        if data and not self.data_received:
-            self.data_received = True
-        return data

neutron/tests/functional/agent/linux/test_ovsdb_monitor.py

@@ -91,9 +91,7 @@ class TestSimpleInterfaceMonitor(BaseMonitorTest):
         self.monitor.start(block=True, timeout=timeout)
 
     def test_has_updates(self):
-        utils.wait_until_true(lambda: self.monitor.data_received is True)
-        self.assertTrue(self.monitor.has_updates,
-                        'Initial call should always be true')
+        utils.wait_until_true(lambda: self.monitor.has_updates)
         # clear the event list
         self.monitor.get_events()
         self.useFixture(net_helpers.OVSPortFixture())
@@ -118,7 +116,7 @@ class TestSimpleInterfaceMonitor(BaseMonitorTest):
                 return True
 
     def test_get_events(self):
-        utils.wait_until_true(lambda: self.monitor.data_received is True)
+        utils.wait_until_true(lambda: self.monitor.has_updates)
         devices = self.monitor.get_events()
         self.assertTrue(devices.get('added'),
                         'Initial call should always be true')

neutron/tests/unit/agent/linux/test_ovsdb_monitor.py

@@ -52,30 +52,6 @@ class TestSimpleInterfaceMonitor(base.BaseTestCase):
         with mock.patch(target, return_value=True):
             self.assertFalse(self.monitor.has_updates)
 
-    def test__kill_sets_data_received_to_false(self):
-        self.monitor.data_received = True
-        with mock.patch(
-                'neutron.agent.linux.ovsdb_monitor.OvsdbMonitor._kill'):
-            self.monitor._kill()
-        self.assertFalse(self.monitor.data_received)
-
-    def test__read_stdout_sets_data_received_and_returns_output(self):
-        output = 'foo'
-        with mock.patch(
-                'neutron.agent.linux.ovsdb_monitor.OvsdbMonitor._read_stdout',
-                return_value=output):
-            result = self.monitor._read_stdout()
-        self.assertTrue(self.monitor.data_received)
-        self.assertEqual(result, output)
-
-    def test__read_stdout_does_not_set_data_received_for_empty_ouput(self):
-        output = None
-        with mock.patch(
-                'neutron.agent.linux.ovsdb_monitor.OvsdbMonitor._read_stdout',
-                return_value=output):
-            self.monitor._read_stdout()
-        self.assertFalse(self.monitor.data_received)
-
     def test_has_updates_after_calling_get_events_is_false(self):
         with mock.patch.object(
                 self.monitor, 'process_events') as process_events: