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Hello,
I'd like to use polling instead of callbacks.
Is it possible to query the result of the action server as it was the case in ROS1 with action_client->get_state() ?
I can't find an equivalent in ROS2 Humble.
Clement
In ROS 2 Humble, when you send out a goal with "async_send_goal", assign the returned future goal handle to a variable. When you need to query for the result, you can just call "async_get_result" or "async_result" (deprecated). For example:
auto future_goal_handle = client_ptr_->async_send_goal(goal_msg, send_goal_options);
rclcpp::spin_until_future_complete(node, future_goal_handle);
auto result = client_ptr_-> async_get_result(future_goal_handle.get());
if (result.get().code == rclcpp_action::ResultCode::SUCCEEDED)
{
return true;
}
Note that the "result" you get is a WrappedResult, so if you want the result message, you need to do something like:
result.get().result
You can also query for goal status through the client goal handle with "get_status" if you are comparing with action_client->get_state() instead.
@GuimingChen The execution get stucked at auto result = client_ptr_-> async_get_result(future_goal_handle.get()); :(
The action is well executed though
hmm... interesting, I thought this should return immediately since it is a std::shared_future. Did it give you any error message? Can you print something in the server side to check which status the goal is currently in when it got stucked? You can try access the goal status in handle accepted callback.
No, there is no error, it just block at the async_get_result() call.
On the server side, the _execute() callback is correctly executed, I can see the message "Goal succeeded" in the terminal.
void SpacecraftController::change_si_state_execute(const std::shared_ptr<GoalHandleChangeSIState> goal_handle)
{
RCLCPP_INFO(this->get_logger(), "Executing goal");
const auto goal = goal_handle->get_goal();
auto result = std::make_shared<ChangeSIState::Result>();
if (emitSiCmd(*goal))
{
result->nb_si_handled = goal->si_list.size();
goal_handle->succeed(result);
RCLCPP_INFO(this->get_logger(), "Goal succeeded");
}
}
Actually there is an error if I kill the blocking node with CTRL+C:
[ERROR] [1679587180.654655117] [rclcpp]: caught std::exception exception when uninstalling signal handlers in rclcpp::~SignalHandler: Invalid argument
cannot publish data, at ./src/rmw_publish.cpp:62 during '__function__'
[ERROR] [1679587180.656454559] [sequencer.rclcpp]: Error in destruction of rcl subscription handle: Failed to delete datareader, at ./src/subscription.cpp:52, at ./src/rcl/subscription.c:183
cannot publish data, at ./src/rmw_publish.cpp:62 during '__function__'
Fail in delete datareader, at ./src/rmw_service.cpp:104 during '__function__'
[ros2run]: Segmentation fault
I tried
auto future_goal_handle = action_client->async_send_goal(goal_msg, send_goal_options);
RCLCPP_INFO(node->get_logger(), "Goal handle valid =%d", future_goal_handle.valid());
RCLCPP_INFO(node->get_logger(), "Goal status =%d", future_goal_handle.get().get()->get_status());
future_goal_handle.valid() returns 1 future_goal_handle.get() blocks the execution
Asked: 2023-03-23 05:10:13 -0500
Seen: 534 times
Last updated: Mar 23 '23
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