diff --git a/.zuul.yaml b/.zuul.yaml
index 723bb7d21b3d89ff35fa899a766e9dfe543c53ee..9052cedb22f5eb97bf917b289fef6a0e7070681f 100644
--- a/.zuul.yaml
+++ b/.zuul.yaml
@@ -28,7 +28,7 @@
     templates:
       - check-requirements
       - lib-forward-testing-python3
-      - openstack-python3-xena-jobs
+      - openstack-python3-yoga-jobs
       - periodic-stable-jobs
       - publish-openstack-docs-pti
       - release-notes-jobs-python3
diff --git a/doc/source/user/usage.rst b/doc/source/user/usage.rst
index 8eca3e58a95bf7359220b1c971ab7a8c2479014f..b62450bb65b7f59aec79c3e11517543e5eca2686 100644
--- a/doc/source/user/usage.rst
+++ b/doc/source/user/usage.rst
@@ -146,7 +146,10 @@ Another usage pattern is to check a limit and usage for a given
 project, outside the scope of enforcement. This may be useful in a
 reporting API to be able to expose to a user the limit and usage
 information that the enforcer would use to judge a resource
-consumption event.
+consumption event. Any limit passed to this API which is not
+registered in keystone will be considered to be zero, in keeping with
+the behavior of the enforcer assuming that "unregistered means no
+quota."
 
 .. note::
    This should ideally not be used to provide your own enforcement of
diff --git a/oslo_limit/fixture.py b/oslo_limit/fixture.py
index 032b7d09a2a24bdac96291c3549e8fc86442fedb..dfea2cbe08d0d90f3d766615f8c32a4b3de717a4 100644
--- a/oslo_limit/fixture.py
+++ b/oslo_limit/fixture.py
@@ -31,7 +31,7 @@ class LimitFixture(fixtures.Fixture):
                            As in reality, only per-project overrides need be
                            provided here; any unmentioned projects or
                            resources will take the registered limit defaults.
-        :type reglimits: dict
+        :type projlimits: dict
         """
         self.reglimits = reglimits
         self.projlimits = projlimits
diff --git a/oslo_limit/limit.py b/oslo_limit/limit.py
index d63f430492b2b6e6ad0593b6a707cd1bc8e938fc..6fc3941b9e9fc52478abd988ae3c06f167173cfb 100644
--- a/oslo_limit/limit.py
+++ b/oslo_limit/limit.py
@@ -12,6 +12,7 @@
 # License for the specific language governing permissions and limitations
 # under the License.
 
+from collections import defaultdict
 from collections import namedtuple
 
 from keystoneauth1 import exceptions as ksa_exceptions
@@ -55,31 +56,34 @@ def _get_keystone_connection():
 
 class Enforcer(object):
 
-    def __init__(self, usage_callback):
+    def __init__(self, usage_callback, cache=True):
         """An object for checking usage against resource limits and requests.
 
         :param usage_callback: A callable function that accepts a project_id
                                string as a parameter and calculates the current
                                usage of a resource.
         :type usage_callback: callable function
+        :param cache: Whether to cache resource limits for the lifetime of this
+                      enforcer. Defaults to True.
+        :type cache: boolean
         """
         if not callable(usage_callback):
             msg = 'usage_callback must be a callable function.'
             raise ValueError(msg)
 
         self.connection = _get_keystone_connection()
-        self.model = self._get_model_impl(usage_callback)
+        self.model = self._get_model_impl(usage_callback, cache=cache)
 
     def _get_enforcement_model(self):
         """Query keystone for the configured enforcement model."""
         return self.connection.get('/limits/model').json()['model']['name']
 
-    def _get_model_impl(self, usage_callback):
+    def _get_model_impl(self, usage_callback, cache=True):
         """get the enforcement model based on configured model in keystone."""
         model = self._get_enforcement_model()
         for impl in _MODELS:
             if model == impl.name:
-                return impl(usage_callback)
+                return impl(usage_callback, cache=cache)
         raise ValueError("enforcement model %s is not supported" % model)
 
     def enforce(self, project_id, deltas):
@@ -88,8 +92,8 @@ class Enforcer(object):
         From the deltas we extract the list of resource types that need to
         have limits enforced on them.
 
-        From keystone we fetch limits relating to this project_id and the
-        endpoint specified in the configuration.
+        From keystone we fetch limits relating to this project_id (if
+        not None) and the endpoint specified in the configuration.
 
         Using the usage_callback specified when creating the enforcer,
         we fetch the existing usage.
@@ -103,8 +107,12 @@ class Enforcer(object):
         a limit of zero, i.e. do not allow any use of a resource type
         that does not have a registered limit.
 
+        Note that if a project_id of None is provided, we just compare
+        against the registered limits (i.e. use this for
+        non-project-scoped limits)
+
         :param project_id: The project to check usage and enforce limits
-                           against.
+                           against (or None).
         :type project_id: string
         :param deltas: An dictionary containing resource names as keys and
                        requests resource quantities as positive integers.
@@ -113,9 +121,11 @@ class Enforcer(object):
         :type deltas: dictionary
 
         :raises exception.ClaimExceedsLimit: when over limits
+
         """
-        if not project_id or not isinstance(project_id, str):
-            msg = 'project_id must be a non-empty string.'
+        if project_id is not None and (
+                not project_id or not isinstance(project_id, str)):
+            msg = 'project_id must be a non-empty string or None.'
             raise ValueError(msg)
         if not isinstance(deltas, dict) or len(deltas) == 0:
             msg = 'deltas must be a non-empty dictionary.'
@@ -140,15 +150,17 @@ class Enforcer(object):
         This should *not* be used to conduct custom enforcement, but
         rather only for reporting.
 
-        :param project_id: The project for which to check usage and limits.
+        :param project_id: The project for which to check usage and limits,
+                           or None.
         :type project_id: string
         :param resources_to_check: A list of resource names to query.
         :type resources_to_check: list
         :returns: A dictionary of name:limit.ProjectUsage for the
                   requested names against the provided project.
         """
-        if not project_id or not isinstance(project_id, str):
-            msg = 'project_id must be a non-empty string.'
+        if project_id is not None and (
+                not project_id or not isinstance(project_id, str)):
+            msg = 'project_id must be a non-empty string or None.'
             raise ValueError(msg)
 
         msg = ('resources_to_check must be non-empty sequence of '
@@ -167,16 +179,26 @@ class Enforcer(object):
         usage = self.model.get_project_usage(project_id, resources_to_check)
 
         return {resource: ProjectUsage(limit, usage[resource])
-                for resource, limit in dict(limits).items()}
+                for resource, limit in limits}
+
+    def get_registered_limits(self, resources_to_check):
+        return self.model.get_registered_limits(resources_to_check)
+
+    def get_project_limits(self, project_id, resources_to_check):
+        return self.model.get_project_limits(project_id,
+                                             resources_to_check)
 
 
 class _FlatEnforcer(object):
 
     name = 'flat'
 
-    def __init__(self, usage_callback):
+    def __init__(self, usage_callback, cache=True):
         self._usage_callback = usage_callback
-        self._utils = _EnforcerUtils()
+        self._utils = _EnforcerUtils(cache=cache)
+
+    def get_registered_limits(self, resources_to_check):
+        return self._utils.get_registered_limits(resources_to_check)
 
     def get_project_limits(self, project_id, resources_to_check):
         return self._utils.get_project_limits(project_id, resources_to_check)
@@ -202,9 +224,12 @@ class _StrictTwoLevelEnforcer(object):
 
     name = 'strict-two-level'
 
-    def __init__(self, usage_callback):
+    def __init__(self, usage_callback, cache=True):
         self._usage_callback = usage_callback
 
+    def get_registered_limits(self, resources_to_check):
+        raise NotImplementedError()
+
     def get_project_limits(self, project_id, resources_to_check):
         raise NotImplementedError()
 
@@ -229,8 +254,13 @@ class _LimitNotFound(Exception):
 class _EnforcerUtils(object):
     """Logic common used by multiple enforcers"""
 
-    def __init__(self):
+    def __init__(self, cache=True):
         self.connection = _get_keystone_connection()
+        self.should_cache = cache
+        # {project_id: {resource_name: project_limit}}
+        self.plimit_cache = defaultdict(dict)
+        # {resource_name: registered_limit}
+        self.rlimit_cache = {}
 
         # get and cache endpoint info
         endpoint_id = CONF.oslo_limit.endpoint_id
@@ -244,7 +274,7 @@ class _EnforcerUtils(object):
     def enforce_limits(project_id, limits, current_usage, deltas):
         """Check that proposed usage is not over given limits
 
-        :param project_id: project being checked
+        :param project_id: project being checked or None
         :param limits: list of (resource_name,limit) pairs
         :param current_usage: dict of resource name and current usage
         :param deltas: dict of resource name and proposed additional usage
@@ -268,42 +298,73 @@ class _EnforcerUtils(object):
             LOG.debug("hit limit for project: %s", over_limit_list)
             raise exception.ProjectOverLimit(project_id, over_limit_list)
 
+    def get_registered_limits(self, resource_names):
+        """Get all the default limits for a given resource name list
+
+        :param resource_names: list of resource_name strings
+        :return: list of (resource_name, limit) pairs
+        """
+        # Using a list to preserve the resource_name order
+        registered_limits = []
+        for resource_name in resource_names:
+            reg_limit = self._get_registered_limit(resource_name)
+            if reg_limit:
+                limit = reg_limit.default_limit
+            else:
+                limit = 0
+            registered_limits.append((resource_name, limit))
+
+        return registered_limits
+
     def get_project_limits(self, project_id, resource_names):
         """Get all the limits for given project a resource_name list
 
-        We will raise ClaimExceedsLimit if no limit is found to ensure that
-        all clients of this library react to this situation in the same way.
+        If a limit is not found, it will be considered to be zero
+        (i.e. no quota)
 
-        :param project_id:
+        :param project_id: project being checked or None
         :param resource_names: list of resource_name strings
         :return: list of (resource_name,limit) pairs
-
-        :raises exception.ClaimExceedsLimit: if no limit is found
         """
         # Using a list to preserver the resource_name order
         project_limits = []
-        missing_limits = []
         for resource_name in resource_names:
             try:
                 limit = self._get_limit(project_id, resource_name)
-                project_limits.append((resource_name, limit))
             except _LimitNotFound:
-                missing_limits.append(resource_name)
-
-        if len(missing_limits) > 0:
-            over_limit_list = [exception.OverLimitInfo(name, 0, 0, 0)
-                               for name in missing_limits]
-            raise exception.ProjectOverLimit(project_id, over_limit_list)
+                limit = 0
+            project_limits.append((resource_name, limit))
 
         return project_limits
 
     def _get_limit(self, project_id, resource_name):
-        # TODO(johngarbutt): might need to cache here
-        project_limit = self._get_project_limit(project_id, resource_name)
+        # If we are configured to cache limits, look in the cache first and use
+        # the cached value if there is one. Else, retrieve the limit and add it
+        # to the cache. Do this for both project limits and registered limits.
+
+        # Look for a project limit first.
+        if (project_id in self.plimit_cache and
+                resource_name in self.plimit_cache[project_id]):
+            return self.plimit_cache[project_id][resource_name].resource_limit
+
+        project_limit = (self._get_project_limit(project_id, resource_name)
+                         if project_id is not None else None)
+
+        if self.should_cache and project_limit:
+            self.plimit_cache[project_id][resource_name] = project_limit
+
         if project_limit:
             return project_limit.resource_limit
 
+        # If there is no project limit, look for a registered limit.
+        if resource_name in self.rlimit_cache:
+            return self.rlimit_cache[resource_name].default_limit
+
         registered_limit = self._get_registered_limit(resource_name)
+
+        if self.should_cache and registered_limit:
+            self.rlimit_cache[resource_name] = registered_limit
+
         if registered_limit:
             return registered_limit.default_limit
 
diff --git a/oslo_limit/opts.py b/oslo_limit/opts.py
index a9dc9f9065eebe3a3d1f9daebc37ded2693eeac7..b944649a3503e8776971b2af49da5849a7b66c66 100644
--- a/oslo_limit/opts.py
+++ b/oslo_limit/opts.py
@@ -44,6 +44,9 @@ def list_opts():
     return [(_option_group,
              copy.deepcopy(_options) +
              loading.get_session_conf_options() +
+             loading.get_auth_plugin_conf_options('password'),
+             loading.get_auth_plugin_conf_options('v2password'),
+             loading.get_auth_plugin_conf_options('v3password'),
              loading.get_adapter_conf_options(include_deprecated=False)
              )]
 
diff --git a/oslo_limit/tests/test_limit.py b/oslo_limit/tests/test_limit.py
index c229b6d0b94f9f382bf7a850c80384e61af822e7..87de31df32125d1587485bae2d2e480f07affaba 100644
--- a/oslo_limit/tests/test_limit.py
+++ b/oslo_limit/tests/test_limit.py
@@ -29,6 +29,7 @@ from oslo_config import fixture as config_fixture
 from oslotest import base
 
 from oslo_limit import exception
+from oslo_limit import fixture
 from oslo_limit import limit
 from oslo_limit import opts
 
@@ -142,13 +143,42 @@ class TestEnforcer(base.BaseTestCase):
         self.assertEqual(expected, enforcer.calculate_usage(project_id,
                                                             ['a', 'b']))
 
+    @mock.patch.object(limit._EnforcerUtils, "_get_project_limit")
+    @mock.patch.object(limit._EnforcerUtils, "_get_registered_limit")
+    def test_calculate_and_enforce_some_missing(self, mock_get_reglimit,
+                                                mock_get_limit):
+        # Registered and project limits for a and b, c is unregistered
+        reg_limits = {'a': mock.MagicMock(default_limit=10),
+                      'b': mock.MagicMock(default_limit=10)}
+        prj_limits = {('bar', 'b'): mock.MagicMock(resource_limit=6)}
+        mock_get_reglimit.side_effect = lambda r: reg_limits.get(r)
+        mock_get_limit.side_effect = lambda p, r: prj_limits.get((p, r))
+
+        # Regardless, we have usage for all three
+        mock_usage = mock.MagicMock()
+        mock_usage.return_value = {'a': 5, 'b': 5, 'c': 5}
+
+        enforcer = limit.Enforcer(mock_usage)
+
+        # When we calculate usage, we should expect the default limit
+        # of zero for the unregistered limit
+        expected = {
+            'a': limit.ProjectUsage(10, 5),
+            'b': limit.ProjectUsage(6, 5),
+            'c': limit.ProjectUsage(0, 5),
+        }
+        self.assertEqual(expected,
+                         enforcer.calculate_usage('bar', ['a', 'b', 'c']))
+
+        # Make sure that if we enforce, we get the expected behavior
+        # of c being considered to be zero
+        self.assertRaises(exception.ProjectOverLimit,
+                          enforcer.enforce, 'bar', {'a': 1, 'b': 0, 'c': 1})
+
     def test_calculate_usage_bad_params(self):
         enforcer = limit.Enforcer(mock.MagicMock())
 
         # Non-string project_id
-        self.assertRaises(ValueError,
-                          enforcer.calculate_usage,
-                          None, ['foo'])
         self.assertRaises(ValueError,
                           enforcer.calculate_usage,
                           123, ['foo'])
@@ -168,6 +198,27 @@ class TestEnforcer(base.BaseTestCase):
                           enforcer.calculate_usage,
                           'project', ['a', 123, 'b'])
 
+    @mock.patch.object(limit._EnforcerUtils, "get_registered_limits")
+    def test_get_registered_limits(self, mock_get_limits):
+        mock_get_limits.return_value = [("a", 1), ("b", 0), ("c", 2)]
+
+        enforcer = limit.Enforcer(lambda: None)
+        limits = enforcer.get_registered_limits(["a", "b", "c"])
+
+        mock_get_limits.assert_called_once_with(["a", "b", "c"])
+        self.assertEqual(mock_get_limits.return_value, limits)
+
+    @mock.patch.object(limit._EnforcerUtils, "get_project_limits")
+    def test_get_project_limits(self, mock_get_limits):
+        project_id = uuid.uuid4().hex
+        mock_get_limits.return_value = [("a", 1), ("b", 0), ("c", 2)]
+
+        enforcer = limit.Enforcer(lambda: None)
+        limits = enforcer.get_project_limits(project_id, ["a", "b", "c"])
+
+        mock_get_limits.assert_called_once_with(project_id, ["a", "b", "c"])
+        self.assertEqual(mock_get_limits.return_value, limits)
+
 
 class TestFlatEnforcer(base.BaseTestCase):
     def setUp(self):
@@ -175,6 +226,27 @@ class TestFlatEnforcer(base.BaseTestCase):
         self.mock_conn = mock.MagicMock()
         limit._SDK_CONNECTION = self.mock_conn
 
+    @mock.patch.object(limit._EnforcerUtils, "get_registered_limits")
+    def test_get_registered_limits(self, mock_get_limits):
+        mock_get_limits.return_value = [("a", 1), ("b", 0), ("c", 2)]
+
+        enforcer = limit._FlatEnforcer(lambda: None)
+        limits = enforcer.get_registered_limits(["a", "b", "c"])
+
+        mock_get_limits.assert_called_once_with(["a", "b", "c"])
+        self.assertEqual(mock_get_limits.return_value, limits)
+
+    @mock.patch.object(limit._EnforcerUtils, "get_project_limits")
+    def test_get_project_limits(self, mock_get_limits):
+        project_id = uuid.uuid4().hex
+        mock_get_limits.return_value = [("a", 1), ("b", 0), ("c", 2)]
+
+        enforcer = limit._FlatEnforcer(lambda: None)
+        limits = enforcer.get_project_limits(project_id, ["a", "b", "c"])
+
+        mock_get_limits.assert_called_once_with(project_id, ["a", "b", "c"])
+        self.assertEqual(mock_get_limits.return_value, limits)
+
     @mock.patch.object(limit._EnforcerUtils, "get_project_limits")
     def test_enforce(self, mock_get_limits):
         mock_usage = mock.MagicMock()
@@ -215,19 +287,25 @@ class TestFlatEnforcer(base.BaseTestCase):
         self.assertEqual(0, over_a.current_usage)
         self.assertEqual(2, over_a.delta)
 
-    @mock.patch.object(limit._EnforcerUtils, "get_project_limits")
-    def test_enforce_raises_on_missing_limit(self, mock_get_limits):
-        mock_usage = mock.MagicMock()
+    @mock.patch.object(limit._EnforcerUtils, "_get_project_limit")
+    @mock.patch.object(limit._EnforcerUtils, "_get_registered_limit")
+    def test_enforce_raises_on_missing_limit(self, mock_get_reglimit,
+                                             mock_get_limit):
+        def mock_usage(*a):
+            return {'a': 1, 'b': 1}
 
         project_id = uuid.uuid4().hex
         deltas = {"a": 0, "b": 0}
-        mock_get_limits.side_effect = exception.ProjectOverLimit(
-            project_id, [exception.OverLimitInfo("a", 0, 0, 0)])
+        mock_get_reglimit.return_value = None
+        mock_get_limit.return_value = None
 
         enforcer = limit._FlatEnforcer(mock_usage)
         self.assertRaises(exception.ProjectOverLimit, enforcer.enforce,
                           project_id, deltas)
 
+        self.assertRaises(exception.ProjectOverLimit, enforcer.enforce,
+                          None, deltas)
+
 
 class TestEnforcerUtils(base.BaseTestCase):
     def setUp(self):
@@ -262,6 +340,33 @@ class TestEnforcerUtils(base.BaseTestCase):
 
         self.assertEqual(foo, reg_limit)
 
+    def test_get_registered_limits(self):
+        fake_endpoint = endpoint.Endpoint()
+        fake_endpoint.service_id = "service_id"
+        fake_endpoint.region_id = "region_id"
+        self.mock_conn.get_endpoint.return_value = fake_endpoint
+
+        # a and c have limits, b doesn't have one
+        empty_iterator = iter([])
+
+        a = registered_limit.RegisteredLimit()
+        a.resource_name = "a"
+        a.default_limit = 1
+        a_iterator = iter([a])
+
+        c = registered_limit.RegisteredLimit()
+        c.resource_name = "c"
+        c.default_limit = 2
+        c_iterator = iter([c])
+
+        self.mock_conn.registered_limits.side_effect = [a_iterator,
+                                                        empty_iterator,
+                                                        c_iterator]
+
+        utils = limit._EnforcerUtils()
+        limits = utils.get_registered_limits(["a", "b", "c"])
+        self.assertEqual([('a', 1), ('b', 0), ('c', 2)], limits)
+
     def test_get_project_limits(self):
         fake_endpoint = endpoint.Endpoint()
         fake_endpoint.service_id = "service_id"
@@ -291,21 +396,75 @@ class TestEnforcerUtils(base.BaseTestCase):
         limits = utils.get_project_limits(project_id, ["a", "b"])
         self.assertEqual([('a', 1), ('b', 2)], limits)
 
-        e = self.assertRaises(exception.ProjectOverLimit,
-                              utils.get_project_limits,
-                              project_id, ["c", "d"])
-        expected = ("Project %s is over a limit for "
-                    "[Resource c is over limit of 0 due to current usage 0 "
-                    "and delta 0, "
-                    "Resource d is over limit of 0 due to current usage 0 "
-                    "and delta 0]")
-        self.assertEqual(expected % project_id, str(e))
-        self.assertEqual(project_id, e.project_id)
-        self.assertEqual(2, len(e.over_limit_info_list))
-        over_c = e.over_limit_info_list[0]
-        self.assertEqual("c", over_c.resource_name)
-        over_d = e.over_limit_info_list[1]
-        self.assertEqual("d", over_d.resource_name)
-        self.assertEqual(0, over_d.limit)
-        self.assertEqual(0, over_d.current_usage)
-        self.assertEqual(0, over_d.delta)
+        limits = utils.get_project_limits(project_id, ["c", "d"])
+        self.assertEqual([('c', 0), ('d', 0)], limits)
+
+    def test_get_limit_cache(self, cache=True):
+        # No project limit and registered limit = 5
+        fix = self.useFixture(fixture.LimitFixture({'foo': 5}, {}))
+        project_id = uuid.uuid4().hex
+
+        utils = limit._EnforcerUtils(cache=cache)
+        foo_limit = utils._get_limit(project_id, 'foo')
+
+        self.assertEqual(5, foo_limit)
+        self.assertEqual(1, fix.mock_conn.registered_limits.call_count)
+
+        # Second call should be cached, so call_count for registered limits
+        # should remain 1. When cache is disabled, it should increase to 2
+        foo_limit = utils._get_limit(project_id, 'foo')
+        self.assertEqual(5, foo_limit)
+        count = 1 if cache else 2
+        self.assertEqual(count, fix.mock_conn.registered_limits.call_count)
+
+        # Add a project limit = 1
+        fix.projlimits[project_id] = {'foo': 1}
+
+        foo_limit = utils._get_limit(project_id, 'foo')
+
+        self.assertEqual(1, foo_limit)
+        # Project limits should have been queried 3 times total, once per
+        # _get_limit call
+        self.assertEqual(3, fix.mock_conn.limits.call_count)
+
+        # Fourth call should be cached, so call_count for project limits should
+        # remain 3. When cache is disabled, it should increase to 4
+        foo_limit = utils._get_limit(project_id, 'foo')
+        self.assertEqual(1, foo_limit)
+        count = 3 if cache else 4
+        self.assertEqual(count, fix.mock_conn.limits.call_count)
+
+    def test_get_limit_no_cache(self):
+        self.test_get_limit_cache(cache=False)
+
+    def test_get_limit(self):
+        utils = limit._EnforcerUtils(cache=False)
+
+        mgpl = mock.MagicMock()
+        mgrl = mock.MagicMock()
+        with mock.patch.multiple(utils, _get_project_limit=mgpl,
+                                 _get_registered_limit=mgrl):
+            # With a project, we expect the project limit to be
+            # fetched. If present, we never check the registered limit.
+            utils._get_limit('project', 'foo')
+            mgrl.assert_not_called()
+            mgpl.assert_called_once_with('project', 'foo')
+
+            mgrl.reset_mock()
+            mgpl.reset_mock()
+
+            # With a project, we expect the project limit to be
+            # fetched. If absent, we check the registered limit.
+            mgpl.return_value = None
+            utils._get_limit('project', 'foo')
+            mgrl.assert_called_once_with('foo')
+            mgpl.assert_called_once_with('project', 'foo')
+
+            mgrl.reset_mock()
+            mgpl.reset_mock()
+
+            # With no project, we expect to get registered limit but
+            # not project limit
+            utils._get_limit(None, 'foo')
+            mgrl.assert_called_once_with('foo')
+            mgpl.assert_not_called()
diff --git a/releasenotes/notes/enforcer-limit-caching-fb59725aad88b039.yaml b/releasenotes/notes/enforcer-limit-caching-fb59725aad88b039.yaml
new file mode 100644
index 0000000000000000000000000000000000000000..c2b45e4ec46856d0f9dae3053d919273f484e328
--- /dev/null
+++ b/releasenotes/notes/enforcer-limit-caching-fb59725aad88b039.yaml
@@ -0,0 +1,7 @@
+---
+features:
+  - |
+    ``Enforcer`` objects now cache limits by default for the lifetime of the
+    object to provide improved performance when multiple calls of ``enforce()``
+    are needed. This behavior is controlled by the boolean ``cache`` keyword
+    argument to the ``__init__`` method.
diff --git a/releasenotes/source/index.rst b/releasenotes/source/index.rst
index 32a2d5b39fdfb1794cf9e5db2896bc45873aeb11..704a9748221c23ce0c55cb84042048ddf901c959 100644
--- a/releasenotes/source/index.rst
+++ b/releasenotes/source/index.rst
@@ -6,6 +6,7 @@
     :maxdepth: 1
 
     unreleased
+    xena
     wallaby
     victoria
     ussuri
diff --git a/releasenotes/source/xena.rst b/releasenotes/source/xena.rst
new file mode 100644
index 0000000000000000000000000000000000000000..1be85be3ebf18741d311aa41096d417a99c970bf
--- /dev/null
+++ b/releasenotes/source/xena.rst
@@ -0,0 +1,6 @@
+=========================
+Xena Series Release Notes
+=========================
+
+.. release-notes::
+   :branch: stable/xena
diff --git a/setup.cfg b/setup.cfg
index abbf8d7692914a7efd2d74ae4a76aae9f6464ded..92aff686adaefcaf028f2f41f331e62044b22e95 100644
--- a/setup.cfg
+++ b/setup.cfg
@@ -1,12 +1,12 @@
 [metadata]
 name = oslo.limit
 summary = Limit enforcement library to assist with quota calculation.
-description-file =
+description_file =
     README.rst
 author = OpenStack
-author-email = openstack-discuss@lists.openstack.org
-home-page = https://docs.openstack.org/oslo.limit/latest/
-python-requires = >=3.6
+author_email = openstack-discuss@lists.openstack.org
+home_page = https://docs.openstack.org/oslo.limit/latest/
+python_requires = >=3.6
 classifier =
     Environment :: OpenStack
     Intended Audience :: Information Technology
diff --git a/tox.ini b/tox.ini
index ee7b5e139b9ad303ac385ad1750960beb4346ad0..54c1f1260e5b09a9e7517a2caf4be691ffafdcaf 100644
--- a/tox.ini
+++ b/tox.ini
@@ -1,5 +1,5 @@
 [tox]
-minversion = 3.2.0
+minversion = 3.18.0
 envlist = py3,pep8,docs
 ignore_basepython_conflict = true
 
@@ -28,7 +28,7 @@ commands = {posargs}
 deps =
   -c{env:TOX_CONSTRAINTS_FILE:https://releases.openstack.org/constraints/upper/master}
   -r{toxinidir}/doc/requirements.txt
-whitelist_externals = rm
+allowlist_externals = rm
 commands =
   rm -fr doc/build
   sphinx-build -W --keep-going -b html doc/source doc/build/html
@@ -37,7 +37,7 @@ commands =
 commands = python setup.py test --coverage --coverage-package-name=oslo_limit --testr-args='{posargs}'
 
 [testenv:releasenotes]
-whitelist_externals = rm
+allowlist_externals = rm
 deps =
   -r{toxinidir}/doc/requirements.txt
 commands =