AP_DDS: Rally get has been extended with a size field

Author: tizianofiorenzani

Tools/ros2/ardupilot_msgs/srv/RallyGet.srv

@@ -5,5 +5,7 @@ uint8 index
 ---
 # True is the retrieved point is valid.
 bool success
+# Size of Rally Points list.
+uint8 size
 # Rally point.
 ardupilot_msgs/Rally rally

libraries/AP_DDS/AP_DDS_Client.cpp

@@ -999,6 +999,7 @@ void AP_DDS_Client::on_request(uxrSession* uxr_session, uxrObjectId object_id, u
         const AP_Rally *rally = AP::rally();
         if (rally->get_rally_point_with_index(rally_get_request.index, rally_location)) {
             rally_get_response.success = true;
+            rally_get_response.size = rally->get_rally_total();
             rally_get_response.rally.point.latitude = rally_location.lat * 1e-7;
             rally_get_response.rally.point.longitude = rally_location.lng * 1e-7;
             rally_get_response.rally.point.altitude = rally_location.alt;

libraries/AP_DDS/Idl/ardupilot_msgs/srv/RallyGet.idl

@@ -6,9 +6,10 @@
 
 module ardupilot_msgs {
   module srv {
+    @verbatim (language="comment", text=
+      "This service requests a Rally point from its ID.")
     struct RallyGet_Request {
       @verbatim (language="comment", text=
-        "This service requests a Rally point from its ID." "\n"
         "Rally Point ID.")
       uint8 index;
     };
@@ -17,6 +18,10 @@ module ardupilot_msgs {
     struct RallyGet_Response {
       boolean success;
 
+      @verbatim (language="comment", text=
+        "Size of Rally Points list.")
+      uint8 size;
+
       @verbatim (language="comment", text=
         "Rally point.")
       ardupilot_msgs::msg::Rally rally;

libraries/AP_DDS/README.md

@@ -306,14 +306,14 @@ response:
 ardupilot_msgs.srv.RallySet_Response(success=True, size=1)
 ```
 
-Get a specific Rally Point:
+Get a specific Rally Point (the same service can be used to request the size of the Rally list):
 
 ```bash
 ros2 service call /ap/rally_get ardupilot_msgs/srv/RallyGet "index: 0"
 requester: making request: ardupilot_msgs.srv.RallyGet_Request(index=0)
 
 response:
-ardupilot_msgs.srv.RallyGet_Response(success=True, rally=ardupilot_msgs.msg.Rally(point=geographic_msgs.msg.GeoPoint(latitude=-35.0, longitude=151.0, altitude=400.0), altitude_frame=0))
+ardupilot_msgs.srv.RallyGet_Response(success=True, size=1, rally=ardupilot_msgs.msg.Rally(point=geographic_msgs.msg.GeoPoint(latitude=-35.0, longitude=151.0, altitude=400.0), altitude_frame=0))
 ```
 
 ## Commanding using ROS 2 Topics