Add try_update_params method (#260)

* Improve  method

* fix tests

* add try_update_params method

Author: saikishor

example/test/example_test_gtest.cpp

@@ -64,6 +64,15 @@ TEST_F(ExampleTest, check_parameters) {
   ASSERT_EQ(params_.ft_sensor.filter_coefficient, 0.1);
 }
 
+TEST_F(ExampleTest, try_update_params) {
+  ASSERT_FALSE(param_listener_->try_update_params(params_));
+
+  const rclcpp ::Parameter new_param("interpolation_mode", "linear");
+  example_test_node_->set_parameter(new_param);
+  ASSERT_TRUE(param_listener_->try_update_params(params_));
+  ASSERT_EQ(params_.interpolation_mode, "linear");
+}
+
 TEST_F(ExampleTest, try_get_params) {
   ASSERT_TRUE(param_listener_->try_get_params(params_));
 

generate_parameter_library_py/generate_parameter_library_py/jinja_templates/cpp/parameter_library_header

@@ -124,6 +124,30 @@ struct StackParams {
       return params_;
     }
 
+    /**
+     * @brief Tries to update the parsed Params object
+     * @param params_in The Params object to update
+     * @return true if the Params object was updated, false if it was already up to date or the mutex could not be locked
+     * @note This function tries to lock the mutex without blocking, so it can be used in a RT loop
+     */
+    bool try_update_params(Params & params_in) const {
+      std::unique_lock<std::mutex> lock(mutex_, std::try_to_lock);
+      if (lock.owns_lock()) {
+        if (const bool is_old = params_in.__stamp != params_.__stamp; is_old) {
+          params_in = params_;
+          return true;
+        }
+      }
+      return false;
+    }
+
+    /**
+     * @brief Tries to get the current Params object
+     * @param params_in The Params object to fill with the current parameters
+     * @return true if mutex can be locked, false if mutex could not be locked
+     * @note The parameters are only filled, when the mutex can be locked and the params timestamp is different
+     * @note This function tries to lock the mutex without blocking, so it can be used in a RT loop
+     */
     bool try_get_params(Params & params_in) const {
       if (mutex_.try_lock()) {
         if (const bool is_old = params_in.__stamp != params_.__stamp; is_old) {