added Queue subclass where put_nowait honors mutex lock, and that can be flushed

bstrd/prodqueue.py

@@ -0,0 +1,24 @@
+from queue import Queue, Full 
+
+
+class ProdQueue(Queue):
+
+    def put_nowait(self, *args, **kwargs):
+        if self.mutex.locked():
+            raise Locked
+
+        super().put_nowait(*args, **kwargs)
+
+
+    def clear(self):
+        with self.mutex:
+            self.queue.clear()
+
+
+
+class Locked(Exception):
+    "Exception raised by ProdQueue.put_nowait() if mutex is locked."
+    pass
+
+
+