hive-common: Add hive.common.functools.once

libs/common/hive/common/functools.py

@@ -0,0 +1,12 @@
+from itertools import count
+
+
+def once(func):
+    """Decorator that ensures func runs only once.
+    """
+    counter = count()
+    def wrapper(*args, **kwargs):
+        if next(counter) != 0:
+            return None
+        return func(*args, **kwargs)
+    return wrapper