[behaviours] default to periodic checks with warnings for action clie…

…nt timeouts (#153)

CHANGELOG.rst

@@ -6,6 +6,10 @@ Forthcoming
 -----------
 * ...
 
+2.0.9 (2020-03-05)
+------------------
+* [behaviours] default to periodic checks with warnings for action client timeouts, `#153 <https://github.com/splintered-reality/py_trees_ros/pull/153>`_
+
 2.0.8 (2020-03-04)
 ------------------
 * [behaviours] wait_for_server_timeout_sec in action clients, `#152 <https://github.com/splintered-reality/py_trees_ros/pull/152>`_

py_trees_ros/action_clients.py

@@ -84,15 +84,21 @@ class FromBlackboard(py_trees.behaviour.Behaviour):
         name: name of the behaviour (default: lowercase class name)
         generate_feedback_message: formatter for feedback messages, takes action_type.Feedback
             messages and returns strings (default: None)
-        wait_for_server_timeout_sec: how long to wait in setup for a server connection
+        wait_for_server_timeout_sec: use negative values for a blocking but periodic check (default: -3.0)
+
+    .. note::
+       The default setting for timeouts (a negative value) will suit
+       most use cases. With this setting the behaviour will periodically check and
+       issue a warning if the server can't be found. Actually aborting the setup can
+       usually be left up to the behaviour tree manager.
     """
     def __init__(self,
                  action_type: typing.Any,
                  action_name: str,
                  key: str,
                  name: str=py_trees.common.Name.AUTO_GENERATED,
                  generate_feedback_message: typing.Callable[[typing.Any], str]=None,
-                 wait_for_server_timeout_sec: float=2.0
+                 wait_for_server_timeout_sec: float=-3.0
                  ):
         super().__init__(name)
         self.action_type = action_type
@@ -144,12 +150,23 @@ def setup(self, **kwargs):
             action_type=self.action_type,
             action_name=self.action_name
         )
-        self.node.get_logger().info(
-            "waiting for action server ... [{}][{}]".format(
-                self.action_name, self.qualified_name
-            )
-        )
-        result = self.action_client.wait_for_server(timeout_sec=self.wait_for_server_timeout_sec)
+        result = None
+        if self.wait_for_server_timeout_sec > 0.0:
+            result = self.action_client.wait_for_server(timeout_sec=self.wait_for_server_timeout_sec)
+        else:
+            iterations = 0
+            period_sec = -1.0*self.wait_for_server_timeout_sec
+            while not result:
+                iterations += 1
+                result = self.action_client.wait_for_server(timeout_sec=period_sec)
+                if not result:
+                    self.node.get_logger().warning(
+                        "waiting for action server ... [{}s][{}][{}]".format(
+                            iterations * period_sec,
+                            self.action_name,
+                            self.qualified_name
+                        )
+                    )
         if not result:
             self.feedback_message = "timed out waiting for the server [{}]".format(self.action_name)
             self.node.get_logger().error("{}[{}]".format(self.feedback_message, self.qualified_name))
@@ -359,16 +376,21 @@ class FromConstant(FromBlackboard):
         name: name of the behaviour (default: lowercase class name)
         generate_feedback_message: formatter for feedback messages, takes action_type.Feedback
             messages and returns strings (default: None)
-        wait_for_server_timeout_sec: how long to wait in setup for a server connection
-                 wait_for_server_timeout_sec: float=2.0
+        wait_for_server_timeout_sec: use negative values for a blocking but periodic check (default: -3.0)
+
+    .. note::
+       The default setting for timeouts (a negative value) will suit
+       most use cases. With this setting the behaviour will periodically check and
+       issue a warning if the server can't be found. Actually aborting the setup can
+       usually be left up to the behaviour tree manager.
     """
     def __init__(self,
                  action_type: typing.Any,
                  action_name: str,
                  action_goal: typing.Any,
                  name: str=py_trees.common.Name.AUTO_GENERATED,
                  generate_feedback_message: typing.Callable[[typing.Any], str]=None,
-                 wait_for_server_timeout_sec: float=2.0
+                 wait_for_server_timeout_sec: float=-3.0
                  ):
         unique_id = uuid.uuid4()
         key = "/goal_" + str(unique_id)

tests/test_action_client.py

@@ -322,7 +322,7 @@ def test_from_blackboard():
 
     py_trees.blackboard.Blackboard.set(
         variable_name="/goal",
-        value=py_trees_actions.Dock.Goal(dock=True)
+        value=py_trees_actions.Dock.Goal(dock=True)  # noqa
     )
 
     tree.tick()