Use HTTP keep-alive feature in HTTPClient class

Currently  HTTPClient creates a new TCP connection for each
API request. We could actually reuse created connections by
relying upon HTTP keep-alive feature.  That would enable us
to do a few queries in a row more efficiently.

Fixes bug 1170385.

Change-Id: Ie6d8fb9670938e3790017509a242630b67abd794

novaclient/client.py

@@ -103,6 +103,8 @@ class HTTPClient(object):
                 # have to set it up here on WARNING (its original level)
                 # otherwise we will get all the requests logging messanges
                 rql.setLevel(logging.WARNING)
+        # requests within the same session can reuse TCP connections from pool
+        self.http = requests.Session()
 
     def use_token_cache(self, use_it):
         self.os_cache = use_it
@@ -161,7 +163,7 @@ class HTTPClient(object):
             kwargs.setdefault('timeout', self.timeout)
 
         self.http_log_req((url, method,), kwargs)
-        resp = requests.request(
+        resp = self.http.request(
             method,
             url,
             verify=self.verify_cert,

tests/test_auth_plugins.py

@@ -92,7 +92,7 @@ class DeprecatedAuthPluginTest(utils.TestCase):
 
         @mock.patch.object(pkg_resources, "iter_entry_points",
                            mock_iter_entry_points)
-        @mock.patch.object(requests, "request", mock_request)
+        @mock.patch.object(requests.Session, "request", mock_request)
         def test_auth_call():
             plugin = auth_plugin.DeprecatedAuthPlugin("fake")
             cs = client.Client("username", "password", "project_id",
@@ -121,7 +121,7 @@ class DeprecatedAuthPluginTest(utils.TestCase):
 
         @mock.patch.object(pkg_resources, "iter_entry_points",
                            mock_iter_entry_points)
-        @mock.patch.object(requests, "request", mock_request)
+        @mock.patch.object(requests.Session, "request", mock_request)
         def test_auth_call():
             auth_plugin.discover_auth_systems()
             plugin = auth_plugin.DeprecatedAuthPlugin("notexists")
@@ -164,7 +164,7 @@ class DeprecatedAuthPluginTest(utils.TestCase):
 
         @mock.patch.object(pkg_resources, "iter_entry_points",
                            mock_iter_entry_points)
-        @mock.patch.object(requests, "request", mock_request)
+        @mock.patch.object(requests.Session, "request", mock_request)
         def test_auth_call():
             plugin = auth_plugin.DeprecatedAuthPlugin("fakewithauthurl")
             cs = client.Client("username", "password", "project_id",
@@ -197,7 +197,7 @@ class DeprecatedAuthPluginTest(utils.TestCase):
 
 
 class AuthPluginTest(utils.TestCase):
-    @mock.patch.object(requests, "request")
+    @mock.patch.object(requests.Session, "request")
     @mock.patch.object(pkg_resources, "iter_entry_points")
     def test_auth_system_success(self, mock_iter_entry_points, mock_request):
         """Test that we can authenticate using the auth system."""

tests/test_client.py

@@ -38,12 +38,12 @@ class ClientTest(utils.TestCase):
             'x-server-management-url': 'blah.com',
             'x-auth-token': 'blah',
         }
-        with mock.patch('requests.request', mock_request):
+        with mock.patch('requests.Session.request', mock_request):
             instance.authenticate()
-            requests.request.assert_called_with(mock.ANY, mock.ANY,
-                                                timeout=2,
-                                                headers=mock.ANY,
-                                                verify=mock.ANY)
+            requests.Session.request.assert_called_with(mock.ANY, mock.ANY,
+                                                        timeout=2,
+                                                        headers=mock.ANY,
+                                                        verify=mock.ANY)
 
     def test_get_client_class_v2(self):
         output = novaclient.client.get_client_class('2')

tests/test_http.py

@@ -43,7 +43,7 @@ class ClientTest(utils.TestCase):
     def test_get(self):
         cl = get_authed_client()
 
-        @mock.patch.object(requests, "request", mock_request)
+        @mock.patch.object(requests.Session, "request", mock_request)
         @mock.patch('time.time', mock.Mock(return_value=1234))
         def test_get_call():
             resp, body = cl.get("/hi")
@@ -65,7 +65,7 @@ class ClientTest(utils.TestCase):
     def test_post(self):
         cl = get_authed_client()
 
-        @mock.patch.object(requests, "request", mock_request)
+        @mock.patch.object(requests.Session, "request", mock_request)
         def test_post_call():
             cl.post("/hi", body=[1, 2, 3])
             headers = {
@@ -88,7 +88,7 @@ class ClientTest(utils.TestCase):
         cl = get_client()
 
         # response must not have x-server-management-url header
-        @mock.patch.object(requests, "request", mock_request)
+        @mock.patch.object(requests.Session, "request", mock_request)
         def test_auth_call():
             self.assertRaises(exceptions.AuthorizationFailure, cl.authenticate)
 
@@ -97,7 +97,7 @@ class ClientTest(utils.TestCase):
     def test_connection_refused(self):
         cl = get_client()
 
-        @mock.patch.object(requests, "request", refused_mock_request)
+        @mock.patch.object(requests.Session, "request", refused_mock_request)
         def test_refused_call():
             self.assertRaises(exceptions.ConnectionRefused, cl.get, "/hi")
 
@@ -106,7 +106,7 @@ class ClientTest(utils.TestCase):
     def test_bad_request(self):
         cl = get_client()
 
-        @mock.patch.object(requests, "request", bad_req_mock_request)
+        @mock.patch.object(requests.Session, "request", bad_req_mock_request)
         def test_refused_call():
             self.assertRaises(exceptions.BadRequest, cl.get, "/hi")
 

tests/v1_1/test_auth.py

@@ -44,7 +44,7 @@ class AuthenticateAgainstKeystoneTests(utils.TestCase):
 
         mock_request = mock.Mock(return_value=(auth_response))
 
-        @mock.patch.object(requests, "request", mock_request)
+        @mock.patch.object(requests.Session, "request", mock_request)
         def test_auth_call():
             cs.client.authenticate()
             headers = {
@@ -90,7 +90,7 @@ class AuthenticateAgainstKeystoneTests(utils.TestCase):
 
         mock_request = mock.Mock(return_value=(auth_response))
 
-        @mock.patch.object(requests, "request", mock_request)
+        @mock.patch.object(requests.Session, "request", mock_request)
         def test_auth_call():
             self.assertRaises(exceptions.Unauthorized, cs.client.authenticate)
 
@@ -147,7 +147,7 @@ class AuthenticateAgainstKeystoneTests(utils.TestCase):
 
         mock_request = mock.Mock(side_effect=side_effect)
 
-        @mock.patch.object(requests, "request", mock_request)
+        @mock.patch.object(requests.Session, "request", mock_request)
         def test_auth_call():
             cs.client.authenticate()
             headers = {
@@ -230,7 +230,7 @@ class AuthenticateAgainstKeystoneTests(utils.TestCase):
 
         mock_request = mock.Mock(return_value=(auth_response))
 
-        @mock.patch.object(requests, "request", mock_request)
+        @mock.patch.object(requests.Session, "request", mock_request)
         def test_auth_call():
             self.assertRaises(exceptions.AmbiguousEndpoints,
                               cs.client.authenticate)
@@ -251,7 +251,7 @@ class AuthenticationTests(utils.TestCase):
         })
         mock_request = mock.Mock(return_value=(auth_response))
 
-        @mock.patch.object(requests, "request", mock_request)
+        @mock.patch.object(requests.Session, "request", mock_request)
         def test_auth_call():
             cs.client.authenticate()
             headers = {
@@ -279,7 +279,7 @@ class AuthenticationTests(utils.TestCase):
         auth_response = utils.TestResponse({'status_code': 401})
         mock_request = mock.Mock(return_value=(auth_response))
 
-        @mock.patch.object(requests, "request", mock_request)
+        @mock.patch.object(requests.Session, "request", mock_request)
         def test_auth_call():
             self.assertRaises(exceptions.Unauthorized, cs.client.authenticate)