added Executor that knows its futures

modman/executing.py

@@ -0,0 +1,21 @@
+from concurrent.futures import ThreadPoolExecutor
+
+
+class Executor(ThreadPoolExecutor):
+
+    def __init__(self):
+        super().__init__()
+        self.futures = {}
+
+    def run(self, name, func, *args, **kwargs):
+        fut = self.submit(func, *args, **kwargs)
+        self.futures[name] = fut
+        return fut
+
+    def cleanup(self):
+        for name, fut in tuple(self.futures.items()):
+            if fut.done():
+                del self.futures[name]
+
+
+