Change oslo_cache implementation

As of now to leverage caching, oslo_cache library has to be imported
and configured everytime it's needed.

This change migrates such implementatio to use `cache_utils.py`
which returns a cache client to perform caching operations. This
eliminates the purpose of importing oslo_cache everytime when needed.

To get a cache client:
```
from ceilometer import cache_utils
.
cache_client = cache_utils.get_client(conf)
```

Signed-off-by: Yadnesh Kulkarni <ykulkarn@redhat.com>
Change-Id: I14f9e1cbe84a953b092c3a88345d5faa9bcc9fb2

1 files changed, 65 insertions, 0 deletions

diff --git a/ceilometer/tests/unit/test_cache_utils.py b/ceilometer/tests/unit/test_cache_utils.py
new file mode 100644
index 00000000..245eaa34
--- /dev/null
+++ b/ceilometer/tests/unit/test_cache_utils.py
@@ -0,0 +1,65 @@
+#
+# Copyright 2022 Red Hat, Inc
+#
+# Licensed under the Apache License, Version 2.0 (the "License"); you may
+# not use this file except in compliance with the License. You may obtain
+# a copy of the License at
+#
+#      http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
+# WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
+# License for the specific language governing permissions and limitations
+# under the License.
+
+from ceilometer import cache_utils
+from ceilometer import service as ceilometer_service
+from oslo_cache import core as cache
+from oslo_config import fixture as config_fixture
+from oslotest import base
+
+
+class CacheConfFixture(config_fixture.Config):
+    def setUp(self):
+        super(CacheConfFixture, self).setUp()
+        self.conf = ceilometer_service.\
+            prepare_service(argv=[], config_files=[])
+        cache.configure(self.conf)
+        self.config(enabled=True, group='cache')
+
+
+class TestOsloCache(base.BaseTestCase):
+    def setUp(self):
+        super(TestOsloCache, self).setUp()
+
+        conf = ceilometer_service.prepare_service(argv=[], config_files=[])
+
+        dict_conf_fixture = CacheConfFixture(conf)
+        self.useFixture(dict_conf_fixture)
+        dict_conf_fixture.config(expiration_time=600,
+                                 backend='oslo_cache.dict',
+                                 group='cache')
+        self.dict_conf = dict_conf_fixture.conf
+
+        # enable_retry_client is only supported by
+        # 'dogpile.cache.pymemcache' backend which makes this
+        # incorrect config
+        faulty_conf_fixture = CacheConfFixture(conf)
+        self.useFixture(faulty_conf_fixture)
+        faulty_conf_fixture.config(expiration_time=600,
+                                   backend='dogpile.cache.memcached',
+                                   group='cache',
+                                   enable_retry_client='true')
+        self.faulty_cache_conf = faulty_conf_fixture.conf
+
+        self.no_cache_conf = ceilometer_service.\
+            prepare_service(argv=[], config_files=[])
+
+    def test_get_cache_region(self):
+        self.assertIsNotNone(cache_utils.get_cache_region(self.dict_conf))
+
+    def test_get_client(self):
+        self.assertIsNotNone(cache_utils.get_client(self.dict_conf))
+        self.assertIsNone(cache_utils.get_client(self.no_cache_conf))
+        self.assertIsNone(cache_utils.get_client(self.faulty_cache_conf))