If the function returns a future, handle things asynchronously

tornadorpc/base.py

@@ -140,7 +140,21 @@ def dispatch(self, method_name, params):
             self.traceback(method_name, params)
             return self.handler.result(self.faults.internal_error())
 
-        if getattr(method, 'async', False):
+        from tornado.concurrent import Future
+        if isinstance(response, Future):
+            # self.handler is actually a transient: BaseRPCParser is used as a
+            # singleton class where self.handler changes each time a request is
+            # processed, so we need to treat it as a temporary, that may change
+            # anytime control flow returns to Tornado's IO handler
+            def make_completer(handler):
+                def completer(future):
+                    handler.result(future.result())
+                return completer
+            if response.done():
+                return self.handler.result(response.result())
+            else:
+                tornado.ioloop.IOLoop.instance().add_future(response, make_completer(self.handler))
+        elif getattr(method, 'async', False):
             # Asynchronous response -- the method should have called
             # self.result(RESULT_VALUE)
             if response is not None: