structure saas with tools

.venv/lib/python3.10/site-packages/opentelemetry/util/_once.py

@@ -0,0 +1,47 @@
+# 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 threading import Lock
+from typing import Callable
+
+
+class Once:
+    """Execute a function exactly once and block all callers until the function returns
+
+    Same as golang's `sync.Once <https://pkg.go.dev/sync#Once>`_
+    """
+
+    def __init__(self) -> None:
+        self._lock = Lock()
+        self._done = False
+
+    def do_once(self, func: Callable[[], None]) -> bool:
+        """Execute ``func`` if it hasn't been executed or return.
+
+        Will block until ``func`` has been called by one thread.
+
+        Returns:
+            Whether or not ``func`` was executed in this call
+        """
+
+        # fast path, try to avoid locking
+        if self._done:
+            return False
+
+        with self._lock:
+            if not self._done:
+                func()
+                self._done = True
+                return True
+        return False