Refactor lock definition

opentelemetry-sdk/src/opentelemetry/sdk/metrics/_internal/exponential_histogram/mapping/__init__.py

@@ -13,13 +13,20 @@
 # limitations under the License.
 
 from abc import ABC, abstractmethod
+from threading import Lock
 
 
 class Mapping(ABC):
 
     # pylint: disable=no-member
     def __new__(cls, scale: int):
 
+        if not hasattr(cls, "_mappings"):
+            cls._mappings = {}
+
+        if not hasattr(cls, "_mappings_lock"):
+            cls._mappings_lock = Lock()
+
         with cls._mappings_lock:
             if scale not in cls._mappings:
                 cls._mappings[scale] = super().__new__(cls)

opentelemetry-sdk/src/opentelemetry/sdk/metrics/_internal/exponential_histogram/mapping/exponent_mapping.py

@@ -34,9 +34,6 @@
 
 class ExponentMapping(Mapping):
 
-    _mappings = {}
-    _mappings_lock = Lock()
-
     _min_scale = -10
     _max_scale = 0
 

opentelemetry-sdk/tests/metrics/exponential_histogram/test_mapping.py

@@ -0,0 +1,57 @@
+# Copyright The OpenTelemetry Authors
+#
+# 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 unittest import TestCase
+from math import inf
+
+from opentelemetry.sdk.metrics._internal.exponential_histogram.mapping import (
+    Mapping,
+)
+
+
+class TestMapping(TestCase):
+
+    def test_lock(self):
+
+        class Child0(Mapping):
+            def _get_max_scale(self) -> int:
+                return inf
+
+            def _get_min_scale(self) -> int:
+                return -inf
+
+            def map_to_index(self, value: float) -> int:
+                pass
+
+            def get_lower_boundary(self, index: int) -> float:
+                pass
+
+        class Child1(Mapping):
+            def _get_max_scale(self) -> int:
+                return inf
+
+            def _get_min_scale(self) -> int:
+                return -inf
+
+            def map_to_index(self, value: float) -> int:
+                pass
+
+            def get_lower_boundary(self, index: int) -> float:
+                pass
+
+        child_0 = Child0(0)
+        child_1 = Child1(1)
+
+        self.assertIsNot(child_0._mappings, child_1._mappings)
+        self.assertIsNot(child_0._mappings_lock, child_1._mappings_lock)