Merge "Cache getters for the decalarative definitions"

ceilometer/declarative.py

@@ -32,6 +32,7 @@ class DefinitionException(Exception):
 
 class Definition(object):
     JSONPATH_RW_PARSER = parser.ExtentedJsonPathParser()
+    GETTERS_CACHE = {}
 
     def __init__(self, name, cfg, plugin_manager):
         self.cfg = cfg
@@ -85,7 +86,7 @@ class Definition(object):
             self.getter = fields
         else:
             try:
-                self.getter = self.JSONPATH_RW_PARSER.parse(fields).find
+                self.getter = self.make_getter(fields)
             except Exception as e:
                 raise DefinitionException(
                     _("Parse error in JSONPath specification "
@@ -123,6 +124,14 @@ class Definition(object):
         else:
             return values[0] if values else None
 
+    def make_getter(self, fields):
+        if fields in self.GETTERS_CACHE:
+            return self.GETTERS_CACHE[fields]
+        else:
+            getter = self.JSONPATH_RW_PARSER.parse(fields).find
+            self.GETTERS_CACHE[fields] = getter
+            return getter
+
 
 def load_definitions(defaults, config_file, fallback_file=None):
     """Setup a definitions from yaml config file."""

ceilometer/tests/unit/test_declarative.py

@@ -0,0 +1,48 @@
+#
+# Copyright 2016 Mirantis, 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.
+
+import mock
+from oslotest import mockpatch
+
+from ceilometer import declarative
+from ceilometer.tests import base
+
+
+class TestDefinition(base.BaseTestCase):
+
+    def setUp(self):
+        super(TestDefinition, self).setUp()
+        self.configs = [
+            "_field1",
+            "_field2|_field3",
+            {'fields': 'field4.`split(., 1, 1)`'},
+            {'fields': ['field5.arg', 'field6'], 'type': 'text'}
+        ]
+        self.parser = mock.MagicMock()
+        parser_patch = mockpatch.Patch(
+            "jsonpath_rw_ext.parser.ExtentedJsonPathParser.parse",
+            new=self.parser)
+        self.useFixture(parser_patch)
+
+    def test_caching_parsers(self):
+        for config in self.configs * 2:
+            declarative.Definition("test", config, mock.MagicMock())
+        self.assertEqual(4, self.parser.call_count)
+        self.parser.assert_has_calls([
+            mock.call("_field1"),
+            mock.call("_field2|_field3"),
+            mock.call("field4.`split(., 1, 1)`"),
+            mock.call("(field5.arg)|(field6)"),
+        ])