add

2026-10-15 20:36:59 +08:00
commit 6bf949949c
7923 changed files with 1369582 additions and 0 deletions
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+# Copyright The OpenTelemetry Authors
+# SPDX-License-Identifier: Apache-2.0
+
+from collections.abc import Callable
+from threading import Lock
+
+
+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