Protect 'show' and 'index' with Retry decorator

Commit 77de9653fd added a RetryRequest
exception to the policy engine for when items disappeared during policy
enforcement lookups. However, the API was not catching them for the
show and list operations.

This patch adds the decorators to the two methods to catch any
retry exception that may be emitted from the policy engine or
wherever else.

Closes-Bug: #1528031
Change-Id: If4aea5245cdbb2ea545e9a96d73386e3c21a3696
(cherry-picked from 2a27361cf5)

neutron/api/v2/base.py

@@ -332,6 +332,7 @@ class Controller(object):
         if hasattr(self, '_nova_notifier'):
             self._nova_notifier.send_network_change(action, orig, returned)
 
+    @db_api.retry_db_errors
     def index(self, request, **kwargs):
         """Returns a list of the requested entity."""
         parent_id = kwargs.get(self._parent_id_name)
@@ -339,6 +340,7 @@ class Controller(object):
         policy.init()
         return self._items(request, True, parent_id)
 
+    @db_api.retry_db_errors
     def show(self, request, id, **kwargs):
         """Returns detailed information about the requested entity."""
         try:

neutron/tests/unit/api/v2/test_base.py

@@ -17,6 +17,7 @@ import os
 
 import mock
 from oslo_config import cfg
+from oslo_db import exception as db_exc
 from oslo_policy import policy as oslo_policy
 from oslo_utils import uuidutils
 import six
@@ -1112,6 +1113,20 @@ class JSONV2TestCase(APIv2TestBase, testlib_api.WebTestCase):
                            expect_errors=True)
         self.assertEqual(res.status_int, 400)
 
+    def test_retry_on_index(self):
+        instance = self.plugin.return_value
+        instance.get_networks.side_effect = [db_exc.RetryRequest(None), []]
+        api = webtest.TestApp(router.APIRouter())
+        api.get(_get_path('networks', fmt=self.fmt))
+        self.assertTrue(instance.get_networks.called)
+
+    def test_retry_on_show(self):
+        instance = self.plugin.return_value
+        instance.get_network.side_effect = [db_exc.RetryRequest(None), {}]
+        api = webtest.TestApp(router.APIRouter())
+        api.get(_get_path('networks', _uuid(), fmt=self.fmt))
+        self.assertTrue(instance.get_network.called)
+
 
 class SubresourceTest(base.BaseTestCase):
     def setUp(self):