Cache service availability results per request

Retrieving the list of available resource types seems to be inordinately
slow on at least some clouds (though not in our gate tests). It appears
that checking service availability is the main culprit. These service
availability checks are also performed during validation of a template,
so they should be as fast as possible.

Previously, we never cached the availability of a service, probably on
the assumption that checking the catalog, once retrieved, would be
quick. It's not clear that we even need to use the user's token to
retrieve the catalog on each request, since all users should see the
same catalog. However, at a minimum we can cache the results for the
request so that we don't need to do multiple lookups of the same service
when validating a single stack or listing the available resource types.
This patch does that, and also caches the results of extension lookups
in Neutron and Cinder for the duration of the request, independently of
the global oslo.cache settings (which, if enabled, can cache the results
across requests).

Change-Id: I0618dc2a35f7323abedccb13ef3d6537eef1d24c
Task: 37974

heat/engine/clients/client_plugin.py

@@ -49,6 +49,7 @@ class ClientPlugin(object):
         self._context = weakref.ref(context)
         self._clients = weakref.ref(context.clients)
         self._client_instances = {}
+        self._endpoint_existence = {}
 
     @property
     def context(self):
@@ -163,14 +164,18 @@ class ClientPlugin(object):
     def does_endpoint_exist(self,
                             service_type,
                             service_name):
-        endpoint_type = self._get_client_option(service_name,
-                                                'endpoint_type')
-        try:
-            self.url_for(service_type=service_type,
-                         endpoint_type=endpoint_type)
-            return True
-        except exceptions.EndpointNotFound:
-            return False
+        endpoint_key = (service_type, service_name)
+        if endpoint_key not in self._endpoint_existence:
+            endpoint_type = self._get_client_option(service_name,
+                                                    'endpoint_type')
+            try:
+                self.url_for(service_type=service_type,
+                             endpoint_type=endpoint_type)
+                self._endpoint_existence[endpoint_key] = True
+            except exceptions.EndpointNotFound:
+                self._endpoint_existence[endpoint_key] = False
+
+        return self._endpoint_existence[endpoint_key]
 
 
 def retry_if_connection_err(exception):

heat/engine/clients/os/__init__.py

@@ -11,6 +11,10 @@
 #    License for the specific language governing permissions and limitations
 #    under the License.
 
+import abc
+
+import six
+
 from oslo_cache import core
 from oslo_config import cfg
 
@@ -25,3 +29,20 @@ MEMOIZE_FINDER = core.get_memoization_decorator(
     conf=cfg.CONF,
     region=cache.get_cache_region(),
     group="resource_finder_cache")
+
+
+@six.add_metaclass(abc.ABCMeta)
+class ExtensionMixin(object):
+    def __init__(self, *args, **kwargs):
+        super(ExtensionMixin, self).__init__(*args, **kwargs)
+        self._extensions = None
+
+    @abc.abstractmethod
+    def _list_extensions(self):
+        return []
+
+    def has_extension(self, alias):
+        """Check if specific extension is present."""
+        if self._extensions is None:
+            self._extensions = set(self._list_extensions())
+        return alias in self._extensions

heat/engine/clients/os/cinder.py

@@ -29,7 +29,8 @@ LOG = logging.getLogger(__name__)
 CLIENT_NAME = 'cinder'
 
 
-class CinderClientPlugin(client_plugin.ClientPlugin):
+class CinderClientPlugin(os_client.ExtensionMixin,
+                         client_plugin.ClientPlugin):
 
     exceptions_module = exceptions
 
@@ -76,10 +77,6 @@ class CinderClientPlugin(client_plugin.ClientPlugin):
         extensions = self.client().list_extensions.show_all()
         return set(extension.alias for extension in extensions)
 
-    def has_extension(self, alias):
-        """Check if specific extension is present."""
-        return alias in self._list_extensions()
-
     def get_volume(self, volume):
         try:
             return self.client().volumes.get(volume)

heat/engine/clients/os/neutron/__init__.py

@@ -23,7 +23,8 @@ from heat.engine.clients import client_plugin
 from heat.engine.clients import os as os_client
 
 
-class NeutronClientPlugin(client_plugin.ClientPlugin):
+class NeutronClientPlugin(os_client.ExtensionMixin,
+                          client_plugin.ClientPlugin):
 
     exceptions_module = exceptions
 
@@ -117,10 +118,6 @@ class NeutronClientPlugin(client_plugin.ClientPlugin):
         extensions = self.client().list_extensions().get('extensions')
         return set(extension.get('alias') for extension in extensions)
 
-    def has_extension(self, alias):
-        """Check if specific extension is present."""
-        return alias in self._list_extensions()
-
     def _resolve(self, props, key, id_key, key_type):
         if props.get(key):
             props[id_key] = self.find_resourceid_by_name_or_id(key_type,