From d7cc83129966109556df8669aa970ff39fd156ed Mon Sep 17 00:00:00 2001
From: Jim Rollenhagen <jim@jimrollenhagen.com>
Date: Tue, 7 Oct 2014 16:24:31 -0700
Subject: [PATCH] Clear hash ring cache in get_topic_for*

This causes the hash ring to be reset on each API request, avoiding
an issue where a new conductor never joins the ring until the API
service is restarted.

Closes-Bug: 1378570

Change-Id: Ic57370163f2f833efab662837036298f29f4ca90
---
 ironic/conductor/rpcapi.py            |  4 ++++
 ironic/tests/conductor/test_rpcapi.py | 31 +++++++++++++++++++++++++++
 2 files changed, 35 insertions(+)

diff --git a/ironic/conductor/rpcapi.py b/ironic/conductor/rpcapi.py
index 4fa96f1aab..452fc0ceeb 100644
--- a/ironic/conductor/rpcapi.py
+++ b/ironic/conductor/rpcapi.py
@@ -87,6 +87,8 @@ class ConductorAPI(object):
         :raises: NoValidHost
 
         """
+        self.ring_manager.reset()
+
         try:
             ring = self.ring_manager[node.driver]
             dest = ring.get_hosts(node.uuid)
@@ -106,6 +108,8 @@ class ConductorAPI(object):
         :raises: DriverNotFound
 
         """
+        self.ring_manager.reset()
+
         hash_ring = self.ring_manager[driver_name]
         host = random.choice(list(hash_ring.hosts))
         return self.topic + "." + host
diff --git a/ironic/tests/conductor/test_rpcapi.py b/ironic/tests/conductor/test_rpcapi.py
index 2715649d6b..47a938c476 100644
--- a/ironic/tests/conductor/test_rpcapi.py
+++ b/ironic/tests/conductor/test_rpcapi.py
@@ -78,6 +78,22 @@ class RPCAPITestCase(base.DbTestCase):
                          rpcapi.get_topic_for,
                          self.fake_node_obj)
 
+    def test_get_topic_doesnt_cache(self):
+        CONF.set_override('host', 'fake-host')
+
+        rpcapi = conductor_rpcapi.ConductorAPI(topic='fake-topic')
+        self.assertRaises(exception.NoValidHost,
+                         rpcapi.get_topic_for,
+                         self.fake_node_obj)
+
+        self.dbapi.register_conductor({'hostname': 'fake-host',
+                                       'drivers': ['fake-driver']})
+
+        rpcapi = conductor_rpcapi.ConductorAPI(topic='fake-topic')
+        expected_topic = 'fake-topic.fake-host'
+        self.assertEqual(expected_topic,
+                         rpcapi.get_topic_for(self.fake_node_obj))
+
     def test_get_topic_for_driver_known_driver(self):
         CONF.set_override('host', 'fake-host')
         self.dbapi.register_conductor({
@@ -99,6 +115,21 @@ class RPCAPITestCase(base.DbTestCase):
                           rpcapi.get_topic_for_driver,
                           'fake-driver')
 
+    def test_get_topic_for_driver_doesnt_cache(self):
+        CONF.set_override('host', 'fake-host')
+        rpcapi = conductor_rpcapi.ConductorAPI(topic='fake-topic')
+        self.assertRaises(exception.DriverNotFound,
+                          rpcapi.get_topic_for_driver,
+                          'fake-driver')
+
+        self.dbapi.register_conductor({
+            'hostname': 'fake-host',
+            'drivers': ['fake-driver'],
+        })
+        rpcapi = conductor_rpcapi.ConductorAPI(topic='fake-topic')
+        self.assertEqual('fake-topic.fake-host',
+                         rpcapi.get_topic_for_driver('fake-driver'))
+
     def _test_rpcapi(self, method, rpc_method, **kwargs):
         rpcapi = conductor_rpcapi.ConductorAPI(topic='fake-topic')