Working async controllers and components [not synchronized] (#1041)

Author: VX792

controller_interface/include/controller_interface/async_controller.hpp

@@ -0,0 +1,111 @@
+// Copyright 2024 ros2_control development team
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+#ifndef CONTROLLER_INTERFACE__ASYNC_CONTROLLER_HPP_
+#define CONTROLLER_INTERFACE__ASYNC_CONTROLLER_HPP_
+
+#include <atomic>
+#include <memory>
+#include <thread>
+
+#include "controller_interface_base.hpp"
+#include "lifecycle_msgs/msg/state.hpp"
+
+namespace controller_interface
+{
+
+class AsyncControllerThread
+{
+public:
+  /// Constructor for the AsyncControllerThread object.
+  /**
+   *
+   * \param[in] controller shared pointer to a controller.
+   * \param[in] cm_update_rate the controller manager's update rate.
+   */
+  AsyncControllerThread(
+    std::shared_ptr<controller_interface::ControllerInterfaceBase> & controller, int cm_update_rate)
+  : terminated_(false), controller_(controller), thread_{}, cm_update_rate_(cm_update_rate)
+  {
+  }
+
+  AsyncControllerThread(const AsyncControllerThread & t) = delete;
+  AsyncControllerThread(AsyncControllerThread && t) = delete;
+
+  // Destructor, called when the component is erased from its map.
+  ~AsyncControllerThread()
+  {
+    terminated_.store(true, std::memory_order_seq_cst);
+    if (thread_.joinable())
+    {
+      thread_.join();
+    }
+  }
+
+  /// Creates the controller's thread.
+  /**
+   * Called when the controller is activated.
+   *
+   */
+  void activate()
+  {
+    thread_ = std::thread(&AsyncControllerThread::controller_update_callback, this);
+  }
+
+  /// Periodically execute the controller's update method.
+  /**
+   * Callback of the async controller's thread.
+   * **Not synchronized with the controller manager's write and read currently**
+   *
+   */
+  void controller_update_callback()
+  {
+    using TimePoint = std::chrono::system_clock::time_point;
+    unsigned int used_update_rate =
+      controller_->get_update_rate() == 0 ? cm_update_rate_ : controller_->get_update_rate();
+
+    auto previous_time = controller_->get_node()->now();
+    while (!terminated_.load(std::memory_order_relaxed))
+    {
+      auto const period = std::chrono::nanoseconds(1'000'000'000 / used_update_rate);
+      TimePoint next_iteration_time =
+        TimePoint(std::chrono::nanoseconds(controller_->get_node()->now().nanoseconds()));
+
+      if (controller_->get_state().id() == lifecycle_msgs::msg::State::PRIMARY_STATE_ACTIVE)
+      {
+        auto const current_time = controller_->get_node()->now();
+        auto const measured_period = current_time - previous_time;
+        previous_time = current_time;
+        controller_->update(
+          controller_->get_node()->now(),
+          (controller_->get_update_rate() != cm_update_rate_ && controller_->get_update_rate() != 0)
+            ? rclcpp::Duration::from_seconds(1.0 / controller_->get_update_rate())
+            : measured_period);
+      }
+
+      next_iteration_time += period;
+      std::this_thread::sleep_until(next_iteration_time);
+    }
+  }
+
+private:
+  std::atomic<bool> terminated_;
+  std::shared_ptr<controller_interface::ControllerInterfaceBase> controller_;
+  std::thread thread_;
+  unsigned int cm_update_rate_;
+};
+
+}  // namespace controller_interface
+
+#endif  // CONTROLLER_INTERFACE__ASYNC_CONTROLLER_HPP_

controller_manager/include/controller_manager/controller_manager.hpp

@@ -23,6 +23,7 @@
 #include <utility>
 #include <vector>
 
+#include "controller_interface/async_controller.hpp"
 #include "controller_interface/chainable_controller_interface.hpp"
 #include "controller_interface/controller_interface.hpp"
 #include "controller_interface/controller_interface_base.hpp"
@@ -196,6 +197,15 @@ class ControllerManager : public rclcpp::Node
   CONTROLLER_MANAGER_PUBLIC
   unsigned int get_update_rate() const;
 
+  /// Deletes all async controllers and components.
+  /**
+   * Needed to join the threads immediately after the control loop is ended
+   * to avoid unnecessary iterations. Otherwise
+   * the threads will be joined only when the controller manager gets destroyed.
+   */
+  CONTROLLER_MANAGER_PUBLIC
+  void shutdown_async_controllers_and_components();
+
 protected:
   CONTROLLER_MANAGER_PUBLIC
   void init_services();
@@ -563,65 +573,7 @@ class ControllerManager : public rclcpp::Node
 
   SwitchParams switch_params_;
 
-  class ControllerThreadWrapper
-  {
-  public:
-    ControllerThreadWrapper(
-      std::shared_ptr<controller_interface::ControllerInterfaceBase> & controller,
-      int cm_update_rate)
-    : terminated_(false), controller_(controller), thread_{}, cm_update_rate_(cm_update_rate)
-    {
-    }
-
-    ControllerThreadWrapper(const ControllerThreadWrapper & t) = delete;
-    ControllerThreadWrapper(ControllerThreadWrapper && t) = default;
-    ~ControllerThreadWrapper()
-    {
-      terminated_.store(true, std::memory_order_seq_cst);
-      if (thread_.joinable())
-      {
-        thread_.join();
-      }
-    }
-
-    void activate()
-    {
-      thread_ = std::thread(&ControllerThreadWrapper::call_controller_update, this);
-    }
-
-    void call_controller_update()
-    {
-      using TimePoint = std::chrono::system_clock::time_point;
-      unsigned int used_update_rate =
-        controller_->get_update_rate() == 0
-          ? cm_update_rate_
-          : controller_
-              ->get_update_rate();  // determines if the controller's or CM's update rate is used
-
-      while (!terminated_.load(std::memory_order_relaxed))
-      {
-        auto const period = std::chrono::nanoseconds(1'000'000'000 / used_update_rate);
-        TimePoint next_iteration_time =
-          TimePoint(std::chrono::nanoseconds(controller_->get_node()->now().nanoseconds()));
-
-        if (controller_->get_state().id() == lifecycle_msgs::msg::State::PRIMARY_STATE_ACTIVE)
-        {
-          // critical section, not implemented yet
-        }
-
-        next_iteration_time += period;
-        std::this_thread::sleep_until(next_iteration_time);
-      }
-    }
-
-  private:
-    std::atomic<bool> terminated_;
-    std::shared_ptr<controller_interface::ControllerInterfaceBase> controller_;
-    std::thread thread_;
-    unsigned int cm_update_rate_;
-  };
-
-  std::unordered_map<std::string, std::unique_ptr<ControllerThreadWrapper>>
+  std::unordered_map<std::string, std::unique_ptr<controller_interface::AsyncControllerThread>>
     async_controller_threads_;
 };
 

controller_manager/src/controller_manager.cpp

@@ -707,7 +707,8 @@ controller_interface::return_type ControllerManager::configure_controller(
   if (controller->is_async())
   {
     async_controller_threads_.emplace(
-      controller_name, std::make_unique<ControllerThreadWrapper>(controller, update_rate_));
+      controller_name,
+      std::make_unique<controller_interface::AsyncControllerThread>(controller, update_rate_));
   }
 
   const auto controller_update_rate = controller->get_update_rate();
@@ -2317,6 +2318,13 @@ std::pair<std::string, std::string> ControllerManager::split_command_interface(
 
 unsigned int ControllerManager::get_update_rate() const { return update_rate_; }
 
+void ControllerManager::shutdown_async_controllers_and_components()
+{
+  async_controller_threads_.erase(
+    async_controller_threads_.begin(), async_controller_threads_.end());
+  resource_manager_->shutdown_async_components();
+}
+
 void ControllerManager::propagate_deactivation_of_chained_mode(
   const std::vector<ControllerSpec> & controllers)
 {

controller_manager/src/ros2_control_node.cpp

@@ -83,6 +83,8 @@ int main(int argc, char ** argv)
         next_iteration_time += period;
         std::this_thread::sleep_until(next_iteration_time);
       }
+
+      cm->shutdown_async_controllers_and_components();
     });
 
   executor->add_node(cm);

hardware_interface/include/hardware_interface/async_components.hpp

@@ -17,6 +17,7 @@
 
 #include <atomic>
 #include <thread>
+#include <type_traits>
 #include <variant>
 
 #include "hardware_interface/actuator.hpp"
@@ -34,29 +35,23 @@ class AsyncComponentThread
 {
 public:
   explicit AsyncComponentThread(
-    Actuator * component, unsigned int update_rate,
+    unsigned int update_rate,
     rclcpp::node_interfaces::NodeClockInterface::SharedPtr clock_interface)
-  : hardware_component_(component), cm_update_rate_(update_rate), clock_interface_(clock_interface)
+  : cm_update_rate_(update_rate), clock_interface_(clock_interface)
   {
   }
 
-  explicit AsyncComponentThread(
-    System * component, unsigned int update_rate,
-    rclcpp::node_interfaces::NodeClockInterface::SharedPtr clock_interface)
-  : hardware_component_(component), cm_update_rate_(update_rate), clock_interface_(clock_interface)
-  {
-  }
-
-  explicit AsyncComponentThread(
-    Sensor * component, unsigned int update_rate,
-    rclcpp::node_interfaces::NodeClockInterface::SharedPtr clock_interface)
-  : hardware_component_(component), cm_update_rate_(update_rate), clock_interface_(clock_interface)
+  // Fills the internal variant with the desired component.
+  template <typename T>
+  void register_component(T * component)
   {
+    hardware_component_ = component;
   }
 
   AsyncComponentThread(const AsyncComponentThread & t) = delete;
-  AsyncComponentThread(AsyncComponentThread && t) = default;
+  AsyncComponentThread(AsyncComponentThread && t) = delete;
 
+  // Destructor, called when the component is erased from its map.
   ~AsyncComponentThread()
   {
     terminated_.store(true, std::memory_order_seq_cst);
@@ -65,9 +60,19 @@ class AsyncComponentThread
       write_and_read_.join();
     }
   }
-
+  /// Creates the component's thread.
+  /**
+   * Called when the component is activated.
+   *
+   */
   void activate() { write_and_read_ = std::thread(&AsyncComponentThread::write_and_read, this); }
 
+  /// Periodically execute the component's write and read methods.
+  /**
+   * Callback of the async component's thread.
+   * **Not synchronized with the controller manager's update currently**
+   *
+   */
   void write_and_read()
   {
     using TimePoint = std::chrono::system_clock::time_point;
@@ -88,8 +93,12 @@ class AsyncComponentThread
             auto measured_period = current_time - previous_time;
             previous_time = current_time;
 
-            // write
-            // read
+            if (!first_iteration)
+            {
+              component->write(clock_interface_->get_clock()->now(), measured_period);
+            }
+            component->read(clock_interface_->get_clock()->now(), measured_period);
+            first_iteration = false;
           }
           next_iteration_time += period;
           std::this_thread::sleep_until(next_iteration_time);
@@ -104,6 +113,7 @@ class AsyncComponentThread
   std::thread write_and_read_{};
 
   unsigned int cm_update_rate_;
+  bool first_iteration = true;
   rclcpp::node_interfaces::NodeClockInterface::SharedPtr clock_interface_;
 };
 

hardware_interface/include/hardware_interface/resource_manager.hpp

@@ -376,6 +376,12 @@ class HARDWARE_INTERFACE_PUBLIC ResourceManager
   return_type set_component_state(
     const std::string & component_name, rclcpp_lifecycle::State & target_state);
 
+  /// Deletes all async components from the resource storage
+  /**
+   * Needed to join the threads immediately after the control loop is ended.
+   */
+  void shutdown_async_components();
+
   /// Reads all loaded hardware components.
   /**
    * Reads from all active hardware components.

hardware_interface/src/resource_manager.cpp

@@ -206,7 +206,9 @@ class ResourceStorage
       {
         async_component_threads_.emplace(
           std::piecewise_construct, std::forward_as_tuple(hardware.get_name()),
-          std::forward_as_tuple(&hardware, cm_update_rate_, clock_interface_));
+          std::forward_as_tuple(cm_update_rate_, clock_interface_));
+
+        async_component_threads_.at(hardware.get_name()).register_component(&hardware);
       }
     }
     return result;
@@ -1324,6 +1326,13 @@ return_type ResourceManager::set_component_state(
   return result;
 }
 
+void ResourceManager::shutdown_async_components()
+{
+  resource_storage_->async_component_threads_.erase(
+    resource_storage_->async_component_threads_.begin(),
+    resource_storage_->async_component_threads_.end());
+}
+
 // CM API: Called in "update"-thread
 HardwareReadWriteStatus ResourceManager::read(
   const rclcpp::Time & time, const rclcpp::Duration & period)