resource_manager.cpp

// Copyright 2020 Open Source Robotics Foundation, Inc.
//
// 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.

#include "hardware_interface/resource_manager.hpp"

#include <functional>
#include <map>
#include <memory>
#include <stdexcept>
#include <string>
#include <tuple>
#include <unordered_map>
#include <utility>
#include <vector>

#include "hardware_interface/actuator.hpp"
#include "hardware_interface/actuator_interface.hpp"
#include "hardware_interface/async_components.hpp"
#include "hardware_interface/component_parser.hpp"
#include "hardware_interface/hardware_component_info.hpp"
#include "hardware_interface/sensor.hpp"
#include "hardware_interface/sensor_interface.hpp"
#include "hardware_interface/system.hpp"
#include "hardware_interface/system_interface.hpp"
#include "hardware_interface/types/hardware_interface_type_values.hpp"
#include "lifecycle_msgs/msg/state.hpp"
#include "pluginlib/class_loader.hpp"
#include "rcutils/logging_macros.h"

namespace hardware_interface
{
auto trigger_and_print_hardware_state_transition =
  [](
    auto transition, const std::string transition_name, const std::string & hardware_name,
    const lifecycle_msgs::msg::State::_id_type & target_state)
{
  RCUTILS_LOG_INFO_NAMED(
    "resource_manager", "'%s' hardware '%s' ", transition_name.c_str(), hardware_name.c_str());

  const rclcpp_lifecycle::State new_state = transition();

  bool result = new_state.id() == target_state;

  if (result)
  {
    RCUTILS_LOG_INFO_NAMED(
      "resource_manager", "Successful '%s' of hardware '%s'", transition_name.c_str(),
      hardware_name.c_str());
  }
  else
  {
    RCUTILS_LOG_INFO_NAMED(
      "resource_manager", "Failed to '%s' hardware '%s'", transition_name.c_str(),
      hardware_name.c_str());
  }
  return result;
};

class ResourceStorage
{
  static constexpr const char * pkg_name = "hardware_interface";

  static constexpr const char * actuator_interface_name = "hardware_interface::ActuatorInterface";
  static constexpr const char * sensor_interface_name = "hardware_interface::SensorInterface";
  static constexpr const char * system_interface_name = "hardware_interface::SystemInterface";

public:
  // TODO(VX792): Change this when HW ifs get their own update rate,
  // because the ResourceStorage really shouldn't know about the cm's parameters
  ResourceStorage(
    unsigned int update_rate = 100,
    rclcpp::node_interfaces::NodeClockInterface::SharedPtr clock_interface = nullptr)
  : actuator_loader_(pkg_name, actuator_interface_name),
    sensor_loader_(pkg_name, sensor_interface_name),
    system_loader_(pkg_name, system_interface_name),
    cm_update_rate_(update_rate),
    clock_interface_(clock_interface)
  {
  }

  template <class HardwareT, class HardwareInterfaceT>
  void load_hardware(
    const HardwareInfo & hardware_info, pluginlib::ClassLoader<HardwareInterfaceT> & loader,
    std::vector<HardwareT> & container)
  {
    RCUTILS_LOG_INFO_NAMED(
      "resource_manager", "Loading hardware '%s' ", hardware_info.name.c_str());
    // hardware_plugin_name has to match class name in plugin xml description
    auto interface = std::unique_ptr<HardwareInterfaceT>(
      loader.createUnmanagedInstance(hardware_info.hardware_plugin_name));
    HardwareT hardware(std::move(interface));
    container.emplace_back(std::move(hardware));
    // initialize static data about hardware component to reduce later calls
    HardwareComponentInfo component_info;
    component_info.name = hardware_info.name;
    component_info.type = hardware_info.type;
    component_info.plugin_name = hardware_info.hardware_plugin_name;
    component_info.is_async = hardware_info.is_async;

    hardware_info_map_.insert(std::make_pair(component_info.name, component_info));
    hardware_used_by_controllers_.insert(
      std::make_pair(component_info.name, std::vector<std::string>()));
  }

  template <class HardwareT>
  bool initialize_hardware(const HardwareInfo & hardware_info, HardwareT & hardware)
  {
    RCUTILS_LOG_INFO_NAMED(
      "resource_manager", "Initialize hardware '%s' ", hardware_info.name.c_str());

    const rclcpp_lifecycle::State new_state = hardware.initialize(hardware_info);

    bool result = new_state.id() == lifecycle_msgs::msg::State::PRIMARY_STATE_UNCONFIGURED;

    if (result)
    {
      RCUTILS_LOG_INFO_NAMED(
        "resource_manager", "Successful initialization of hardware '%s'",
        hardware_info.name.c_str());
    }
    else
    {
      RCUTILS_LOG_INFO_NAMED(
        "resource_manager", "Failed to initialize hardware '%s'", hardware_info.name.c_str());
    }
    return result;
  }

  template <class HardwareT>
  bool configure_hardware(HardwareT & hardware)
  {
    bool result = trigger_and_print_hardware_state_transition(
      std::bind(&HardwareT::configure, &hardware), "configure", hardware.get_name(),
      lifecycle_msgs::msg::State::PRIMARY_STATE_INACTIVE);

    if (result)
    {
      // TODO(destogl): is it better to check here if previous state was unconfigured instead of
      // checking if each state already exists? Or we should somehow know that transition has
      // happened and only then trigger this part of the code?
      // On the other side this part of the code should never be executed in real-time critical
      // thread, so it could be also OK as it is...
      for (const auto & interface : hardware_info_map_[hardware.get_name()].state_interfaces)
      {
        // add all state interfaces to available list
        auto found_it = std::find(
          available_state_interfaces_.begin(), available_state_interfaces_.end(), interface);

        if (found_it == available_state_interfaces_.end())
        {
          available_state_interfaces_.emplace_back(interface);
          RCUTILS_LOG_DEBUG_NAMED(
            "resource_manager", "(hardware '%s'): '%s' state interface added into available list",
            hardware.get_name().c_str(), interface.c_str());
        }
        else
        {
          // TODO(destogl): do here error management if interfaces are only partially added into
          // "available" list - this should never be the case!
          RCUTILS_LOG_WARN_NAMED(
            "resource_manager",
            "(hardware '%s'): '%s' state interface already in available list."
            " This can happen due to multiple calls to 'configure'",
            hardware.get_name().c_str(), interface.c_str());
        }
      }

      // add command interfaces to available list
      for (const auto & interface : hardware_info_map_[hardware.get_name()].command_interfaces)
      {
        // TODO(destogl): check if interface should be available on configure
        auto found_it = std::find(
          available_command_interfaces_.begin(), available_command_interfaces_.end(), interface);

        if (found_it == available_command_interfaces_.end())
        {
          available_command_interfaces_.emplace_back(interface);
          RCUTILS_LOG_DEBUG_NAMED(
            "resource_manager", "(hardware '%s'): '%s' command interface added into available list",
            hardware.get_name().c_str(), interface.c_str());
        }
        else
        {
          // TODO(destogl): do here error management if interfaces are only partially added into
          // "available" list - this should never be the case!
          RCUTILS_LOG_WARN_NAMED(
            "resource_manager",
            "(hardware '%s'): '%s' command interface already in available list."
            " This can happen due to multiple calls to 'configure'",
            hardware.get_name().c_str(), interface.c_str());
        }
      }

      if (hardware_info_map_[hardware.get_name()].is_async)
      {
        async_component_threads_.emplace(
          std::piecewise_construct, std::forward_as_tuple(hardware.get_name()),
          std::forward_as_tuple(&hardware, cm_update_rate_, clock_interface_));
      }
    }
    return result;
  }

  void remove_all_hardware_interfaces_from_available_list(const std::string & hardware_name)
  {
    // remove all command interfaces from available list
    for (const auto & interface : hardware_info_map_[hardware_name].command_interfaces)
    {
      auto found_it = std::find(
        available_command_interfaces_.begin(), available_command_interfaces_.end(), interface);

      if (found_it != available_command_interfaces_.end())
      {
        available_command_interfaces_.erase(found_it);
        RCUTILS_LOG_DEBUG_NAMED(
          "resource_manager", "(hardware '%s'): '%s' command interface removed from available list",
          hardware_name.c_str(), interface.c_str());
      }
      else
      {
        // TODO(destogl): do here error management if interfaces are only partially added into
        // "available" list - this should never be the case!
        RCUTILS_LOG_WARN_NAMED(
          "resource_manager",
          "(hardware '%s'): '%s' command interface not in available list. "
          "This should not happen (hint: multiple cleanup calls).",
          hardware_name.c_str(), interface.c_str());
      }
    }
    // remove all state interfaces from available list
    for (const auto & interface : hardware_info_map_[hardware_name].state_interfaces)
    {
      auto found_it = std::find(
        available_state_interfaces_.begin(), available_state_interfaces_.end(), interface);

      if (found_it != available_state_interfaces_.end())
      {
        available_state_interfaces_.erase(found_it);
        RCUTILS_LOG_DEBUG_NAMED(
          "resource_manager", "(hardware '%s'): '%s' state interface removed from available list",
          hardware_name.c_str(), interface.c_str());
      }
      else
      {
        // TODO(destogl): do here error management if interfaces are only partially added into
        // "available" list - this should never be the case!
        RCUTILS_LOG_WARN_NAMED(
          "resource_manager",
          "(hardware '%s'): '%s' state interface not in available list. "
          "This should not happen (hint: multiple cleanup calls).",
          hardware_name.c_str(), interface.c_str());
      }
    }
  }

  template <class HardwareT>
  bool cleanup_hardware(HardwareT & hardware)
  {
    bool result = trigger_and_print_hardware_state_transition(
      std::bind(&HardwareT::cleanup, &hardware), "cleanup", hardware.get_name(),
      lifecycle_msgs::msg::State::PRIMARY_STATE_UNCONFIGURED);

    if (result)
    {
      remove_all_hardware_interfaces_from_available_list(hardware.get_name());
    }
    return result;
  }

  template <class HardwareT>
  bool shutdown_hardware(HardwareT & hardware)
  {
    bool result = trigger_and_print_hardware_state_transition(
      std::bind(&HardwareT::shutdown, &hardware), "shutdown", hardware.get_name(),
      lifecycle_msgs::msg::State::PRIMARY_STATE_FINALIZED);

    if (result)
    {
      remove_all_hardware_interfaces_from_available_list(hardware.get_name());
      async_component_threads_.erase(hardware.get_name());
      // TODO(destogl): change this - deimport all things if there is there are interfaces there
      // deimport_non_movement_command_interfaces(hardware);
      // deimport_state_interfaces(hardware);
      // use remove_command_interfaces(hardware);
    }
    return result;
  }

  template <class HardwareT>
  bool activate_hardware(HardwareT & hardware)
  {
    bool result = trigger_and_print_hardware_state_transition(
      std::bind(&HardwareT::activate, &hardware), "activate", hardware.get_name(),
      lifecycle_msgs::msg::State::PRIMARY_STATE_ACTIVE);

    if (result)
    {
      if (async_component_threads_.find(hardware.get_name()) != async_component_threads_.end())
      {
        async_component_threads_.at(hardware.get_name()).activate();
      }
      // TODO(destogl): make all command interfaces available (currently are all available)
    }

    return result;
  }

  template <class HardwareT>
  bool deactivate_hardware(HardwareT & hardware)
  {
    bool result = trigger_and_print_hardware_state_transition(
      std::bind(&HardwareT::deactivate, &hardware), "deactivate", hardware.get_name(),
      lifecycle_msgs::msg::State::PRIMARY_STATE_INACTIVE);

    if (result)
    {
      // TODO(destogl): make all command interfaces unavailable that should be present only
      // when active (currently are all available) also at inactive
    }
    return result;
  }

  template <class HardwareT>
  bool set_component_state(HardwareT & hardware, const rclcpp_lifecycle::State & target_state)
  {
    using lifecycle_msgs::msg::State;

    bool result = false;

    switch (target_state.id())
    {
      case State::PRIMARY_STATE_UNCONFIGURED:
        switch (hardware.get_state().id())
        {
          case State::PRIMARY_STATE_UNCONFIGURED:
            result = true;
            break;
          case State::PRIMARY_STATE_INACTIVE:
            result = cleanup_hardware(hardware);
            break;
          case State::PRIMARY_STATE_ACTIVE:
            result = deactivate_hardware(hardware);
            if (result)
            {
              result = cleanup_hardware(hardware);
            }
            break;
          case State::PRIMARY_STATE_FINALIZED:
            result = false;
            RCUTILS_LOG_WARN_NAMED(
              "resource_manager", "hardware '%s' is in finalized state and can be only destroyed.",
              hardware.get_name().c_str());
            break;
        }
        break;
      case State::PRIMARY_STATE_INACTIVE:
        switch (hardware.get_state().id())
        {
          case State::PRIMARY_STATE_UNCONFIGURED:
            result = configure_hardware(hardware);
            break;
          case State::PRIMARY_STATE_INACTIVE:
            result = true;
            break;
          case State::PRIMARY_STATE_ACTIVE:
            result = deactivate_hardware(hardware);
            break;
          case State::PRIMARY_STATE_FINALIZED:
            result = false;
            RCUTILS_LOG_WARN_NAMED(
              "resource_manager", "hardware '%s' is in finalized state and can be only destroyed.",
              hardware.get_name().c_str());
            break;
        }
        break;
      case State::PRIMARY_STATE_ACTIVE:
        switch (hardware.get_state().id())
        {
          case State::PRIMARY_STATE_UNCONFIGURED:
            result = configure_hardware(hardware);
            if (result)
            {
              result = activate_hardware(hardware);
            }
            break;
          case State::PRIMARY_STATE_INACTIVE:
            result = activate_hardware(hardware);
            break;
          case State::PRIMARY_STATE_ACTIVE:
            result = true;
            break;
          case State::PRIMARY_STATE_FINALIZED:
            result = false;
            RCUTILS_LOG_WARN_NAMED(
              "resource_manager", "hardware '%s' is in finalized state and can be only destroyed.",
              hardware.get_name().c_str());
            break;
        }
        break;
      case State::PRIMARY_STATE_FINALIZED:
        switch (hardware.get_state().id())
        {
          case State::PRIMARY_STATE_UNCONFIGURED:
            result = shutdown_hardware(hardware);
            break;
          case State::PRIMARY_STATE_INACTIVE:
            result = shutdown_hardware(hardware);
            break;
          case State::PRIMARY_STATE_ACTIVE:
            result = shutdown_hardware(hardware);
            break;
          case State::PRIMARY_STATE_FINALIZED:
            result = true;
            break;
        }
        break;
    }

    return result;
  }

  template <class HardwareT>
  void import_state_interfaces(HardwareT & hardware)
  {
    auto interfaces = hardware.export_state_interfaces();
    std::vector<std::string> interface_names;
    interface_names.reserve(interfaces.size());
    for (auto & interface : interfaces)
    {
      auto key = interface.get_name();
      state_interface_map_.emplace(std::make_pair(key, std::move(interface)));
      interface_names.push_back(key);
    }
    hardware_info_map_[hardware.get_name()].state_interfaces = interface_names;
    available_state_interfaces_.reserve(
      available_state_interfaces_.capacity() + interface_names.size());
  }

  template <class HardwareT>
  void import_command_interfaces(HardwareT & hardware)
  {
    auto interfaces = hardware.export_command_interfaces();
    hardware_info_map_[hardware.get_name()].command_interfaces = add_command_interfaces(interfaces);
  }

  /// Adds exported command interfaces into internal storage.
  /**
   * Add command interfaces to the internal storage. Command interfaces exported from hardware or
   * chainable controllers are moved to the map with name-interface pairs, the interface names are
   * added to the claimed map and available list's size is increased to reserve storage when
   * interface change theirs status in real-time control loop.
   *
   * \param[interfaces] list of command interface to add into storage.
   * \returns list of interface names that are added into internal storage. The output is used to
   * avoid additional iterations to cache interface names, e.g., for initializing info structures.
   */
  std::vector<std::string> add_command_interfaces(std::vector<CommandInterface> & interfaces)
  {
    std::vector<std::string> interface_names;
    interface_names.reserve(interfaces.size());
    for (auto & interface : interfaces)
    {
      auto key = interface.get_name();
      command_interface_map_.emplace(std::make_pair(key, std::move(interface)));
      claimed_command_interface_map_.emplace(std::make_pair(key, false));
      interface_names.push_back(key);
    }
    available_command_interfaces_.reserve(
      available_command_interfaces_.capacity() + interface_names.size());

    return interface_names;
  }

  /// Removes command interfaces from internal storage.
  /**
   * Command interface are removed from the maps with theirs storage and their claimed status.
   *
   * \param[interface_names] list of command interface names to remove from storage.
   */
  void remove_command_interfaces(const std::vector<std::string> & interface_names)
  {
    for (const auto & interface : interface_names)
    {
      command_interface_map_.erase(interface);
      claimed_command_interface_map_.erase(interface);
    }
  }

  void check_for_duplicates(const HardwareInfo & hardware_info)
  {
    // Check for identical names
    if (hardware_info_map_.find(hardware_info.name) != hardware_info_map_.end())
    {
      throw std::runtime_error(
        "Hardware name " + hardware_info.name +
        " is duplicated. Please provide a unique 'name' in the URDF.");
    }
  }

  // TODO(destogl): Propagate "false" up, if happens in initialize_hardware
  void load_and_initialize_actuator(const HardwareInfo & hardware_info)
  {
    auto load_and_init_actuators = [&](auto & container)
    {
      check_for_duplicates(hardware_info);
      load_hardware<Actuator, ActuatorInterface>(hardware_info, actuator_loader_, container);
      if (initialize_hardware(hardware_info, container.back()))
      {
        import_state_interfaces(container.back());
        import_command_interfaces(container.back());
      }
      else
      {
        RCUTILS_LOG_WARN_NAMED(
          "resource_manager",
          "Actuator hardware component '%s' from plugin '%s' failed to initialize.",
          hardware_info.name.c_str(), hardware_info.hardware_plugin_name.c_str());
      }
    };

    if (hardware_info.is_async)
    {
      load_and_init_actuators(async_actuators_);
    }
    else
    {
      load_and_init_actuators(actuators_);
    }
  }

  void load_and_initialize_sensor(const HardwareInfo & hardware_info)
  {
    auto load_and_init_sensors = [&](auto & container)
    {
      check_for_duplicates(hardware_info);
      load_hardware<Sensor, SensorInterface>(hardware_info, sensor_loader_, container);
      if (initialize_hardware(hardware_info, container.back()))
      {
        import_state_interfaces(container.back());
      }
      else
      {
        RCUTILS_LOG_WARN_NAMED(
          "resource_manager",
          "Sensor hardware component '%s' from plugin '%s' failed to initialize.",
          hardware_info.name.c_str(), hardware_info.hardware_plugin_name.c_str());
      }
    };

    if (hardware_info.is_async)
    {
      load_and_init_sensors(async_sensors_);
    }
    else
    {
      load_and_init_sensors(sensors_);
    }
  }

  void load_and_initialize_system(const HardwareInfo & hardware_info)
  {
    auto load_and_init_systems = [&](auto & container)
    {
      check_for_duplicates(hardware_info);
      load_hardware<System, SystemInterface>(hardware_info, system_loader_, container);
      if (initialize_hardware(hardware_info, container.back()))
      {
        import_state_interfaces(container.back());
        import_command_interfaces(container.back());
      }
      else
      {
        RCUTILS_LOG_WARN_NAMED(
          "resource_manager",
          "System hardware component '%s' from plugin '%s' failed to initialize.",
          hardware_info.name.c_str(), hardware_info.hardware_plugin_name.c_str());
      }
    };

    if (hardware_info.is_async)
    {
      load_and_init_systems(async_systems_);
    }
    else
    {
      load_and_init_systems(systems_);
    }
  }

  void initialize_actuator(
    std::unique_ptr<ActuatorInterface> actuator, const HardwareInfo & hardware_info)
  {
    auto init_actuators = [&](auto & container)
    {
      container.emplace_back(Actuator(std::move(actuator)));
      if (initialize_hardware(hardware_info, container.back()))
      {
        import_state_interfaces(container.back());
        import_command_interfaces(container.back());
      }
      else
      {
        RCUTILS_LOG_WARN_NAMED(
          "resource_manager",
          "Actuator hardware component '%s' from plugin '%s' failed to initialize.",
          hardware_info.name.c_str(), hardware_info.hardware_plugin_name.c_str());
      }
    };

    if (hardware_info.is_async)
    {
      init_actuators(async_actuators_);
    }
    else
    {
      init_actuators(actuators_);
    }
  }

  void initialize_sensor(
    std::unique_ptr<SensorInterface> sensor, const HardwareInfo & hardware_info)
  {
    auto init_sensors = [&](auto & container)
    {
      container.emplace_back(Sensor(std::move(sensor)));
      if (initialize_hardware(hardware_info, container.back()))
      {
        import_state_interfaces(container.back());
      }
      else
      {
        RCUTILS_LOG_WARN_NAMED(
          "resource_manager",
          "Sensor hardware component '%s' from plugin '%s' failed to initialize.",
          hardware_info.name.c_str(), hardware_info.hardware_plugin_name.c_str());
      }
    };

    if (hardware_info.is_async)
    {
      init_sensors(async_sensors_);
    }
    else
    {
      init_sensors(sensors_);
    }
  }

  void initialize_system(
    std::unique_ptr<SystemInterface> system, const HardwareInfo & hardware_info)
  {
    auto init_systems = [&](auto & container)
    {
      container.emplace_back(System(std::move(system)));
      if (initialize_hardware(hardware_info, container.back()))
      {
        import_state_interfaces(container.back());
        import_command_interfaces(container.back());
      }
      else
      {
        RCUTILS_LOG_WARN_NAMED(
          "resource_manager",
          "System hardware component '%s' from plugin '%s' failed to initialize.",
          hardware_info.name.c_str(), hardware_info.hardware_plugin_name.c_str());
      }
    };

    if (hardware_info.is_async)
    {
      init_systems(async_systems_);
    }
    else
    {
      init_systems(systems_);
    }
  }

  // hardware plugins
  pluginlib::ClassLoader<ActuatorInterface> actuator_loader_;
  pluginlib::ClassLoader<SensorInterface> sensor_loader_;
  pluginlib::ClassLoader<SystemInterface> system_loader_;

  std::vector<Actuator> actuators_;
  std::vector<Sensor> sensors_;
  std::vector<System> systems_;

  std::vector<Actuator> async_actuators_;
  std::vector<Sensor> async_sensors_;
  std::vector<System> async_systems_;

  std::unordered_map<std::string, HardwareComponentInfo> hardware_info_map_;

  /// Mapping between hardware and controllers that are using it (accessing data from it)
  std::unordered_map<std::string, std::vector<std::string>> hardware_used_by_controllers_;

  /// Mapping between controllers and list of reference interfaces they are using
  std::unordered_map<std::string, std::vector<std::string>> controllers_reference_interfaces_map_;

  /// Storage of all available state interfaces
  std::map<std::string, StateInterface> state_interface_map_;
  /// Storage of all available command interfaces
  std::map<std::string, CommandInterface> command_interface_map_;

  /// Vectors with interfaces available to controllers (depending on hardware component state)
  std::vector<std::string> available_state_interfaces_;
  std::vector<std::string> available_command_interfaces_;

  /// List of all claimed command interfaces
  std::unordered_map<std::string, bool> claimed_command_interface_map_;

  /// List of async components by type
  std::unordered_map<std::string, AsyncComponentThread> async_component_threads_;

  // Update rate of the controller manager, and the clock interface of its node
  // Used by async components.
  unsigned int cm_update_rate_;
  rclcpp::node_interfaces::NodeClockInterface::SharedPtr clock_interface_;
};

ResourceManager::ResourceManager(
  unsigned int update_rate, rclcpp::node_interfaces::NodeClockInterface::SharedPtr clock_interface)
: resource_storage_(std::make_unique<ResourceStorage>(update_rate, clock_interface))
{
}

ResourceManager::~ResourceManager() = default;

ResourceManager::ResourceManager(
  const std::string & urdf, bool validate_interfaces, bool activate_all, unsigned int update_rate,
  rclcpp::node_interfaces::NodeClockInterface::SharedPtr clock_interface)
: resource_storage_(std::make_unique<ResourceStorage>(update_rate, clock_interface))
{
  load_urdf(urdf, validate_interfaces);

  if (activate_all)
  {
    for (auto const & hw_info : resource_storage_->hardware_info_map_)
    {
      using lifecycle_msgs::msg::State;
      rclcpp_lifecycle::State state(State::PRIMARY_STATE_ACTIVE, lifecycle_state_names::ACTIVE);
      set_component_state(hw_info.first, state);
    }
  }
}

// CM API: Called in "callback/slow"-thread
void ResourceManager::load_urdf(
  const std::string & urdf, bool validate_interfaces, bool load_and_initialize_components)
{
  is_urdf_loaded__ = true;
  const std::string system_type = "system";
  const std::string sensor_type = "sensor";
  const std::string actuator_type = "actuator";

  const auto hardware_info = hardware_interface::parse_control_resources_from_urdf(urdf);
  if (load_and_initialize_components)
  {
    for (const auto & individual_hardware_info : hardware_info)
    {
      if (individual_hardware_info.type == actuator_type)
      {
        std::scoped_lock guard(resource_interfaces_lock_, claimed_command_interfaces_lock_);
        resource_storage_->load_and_initialize_actuator(individual_hardware_info);
      }
      if (individual_hardware_info.type == sensor_type)
      {
        std::lock_guard<std::recursive_mutex> guard(resource_interfaces_lock_);
        resource_storage_->load_and_initialize_sensor(individual_hardware_info);
      }
      if (individual_hardware_info.type == system_type)
      {
        std::scoped_lock guard(resource_interfaces_lock_, claimed_command_interfaces_lock_);
        resource_storage_->load_and_initialize_system(individual_hardware_info);
      }
    }
  }

  // throw on missing state and command interfaces, not specified keys are being ignored
  if (validate_interfaces)
  {
    validate_storage(hardware_info);
  }

  std::lock_guard<std::recursive_mutex> guard(resources_lock_);
  read_write_status.failed_hardware_names.reserve(
    resource_storage_->actuators_.size() + resource_storage_->sensors_.size() +
    resource_storage_->systems_.size());
}

bool ResourceManager::is_urdf_already_loaded() const { return is_urdf_loaded__; }

// CM API: Called in "update"-thread
LoanedStateInterface ResourceManager::claim_state_interface(const std::string & key)
{
  if (!state_interface_is_available(key))
  {
    throw std::runtime_error(std::string("State interface with key '") + key + "' does not exist");
  }

  std::lock_guard<std::recursive_mutex> guard(resource_interfaces_lock_);
  return LoanedStateInterface(resource_storage_->state_interface_map_.at(key));
}

// CM API: Called in "callback/slow"-thread
std::vector<std::string> ResourceManager::state_interface_keys() const
{
  std::vector<std::string> keys;
  std::lock_guard<std::recursive_mutex> guard(resource_interfaces_lock_);
  for (const auto & item : resource_storage_->state_interface_map_)
  {
    keys.push_back(std::get<0>(item));
  }
  return keys;
}

// CM API: Called in "update"-thread
std::vector<std::string> ResourceManager::available_state_interfaces() const
{
  std::lock_guard<std::recursive_mutex> guard(resource_interfaces_lock_);
  return resource_storage_->available_state_interfaces_;
}

// CM API: Called in "update"-thread (indirectly through `claim_state_interface`)
bool ResourceManager::state_interface_is_available(const std::string & name) const
{
  std::lock_guard<std::recursive_mutex> guard(resource_interfaces_lock_);
  return std::find(
           resource_storage_->available_state_interfaces_.begin(),
           resource_storage_->available_state_interfaces_.end(),
           name) != resource_storage_->available_state_interfaces_.end();
}

// CM API: Called in "callback/slow"-thread
void ResourceManager::import_controller_reference_interfaces(
  const std::string & controller_name, std::vector<CommandInterface> & interfaces)
{
  std::scoped_lock guard(resource_interfaces_lock_, claimed_command_interfaces_lock_);
  auto interface_names = resource_storage_->add_command_interfaces(interfaces);
  resource_storage_->controllers_reference_interfaces_map_[controller_name] = interface_names;
}

// CM API: Called in "callback/slow"-thread
std::vector<std::string> ResourceManager::get_controller_reference_interface_names(
  const std::string & controller_name)
{
  return resource_storage_->controllers_reference_interfaces_map_.at(controller_name);
}

// CM API: Called in "update"-thread
void ResourceManager::make_controller_reference_interfaces_available(
  const std::string & controller_name)
{
  auto interface_names =
    resource_storage_->controllers_reference_interfaces_map_.at(controller_name);
  std::lock_guard<std::recursive_mutex> guard(resource_interfaces_lock_);
  resource_storage_->available_command_interfaces_.insert(
    resource_storage_->available_command_interfaces_.end(), interface_names.begin(),
    interface_names.end());
}

// CM API: Called in "update"-thread
void ResourceManager::make_controller_reference_interfaces_unavailable(
  const std::string & controller_name)
{
  auto interface_names =
    resource_storage_->controllers_reference_interfaces_map_.at(controller_name);

  std::lock_guard<std::recursive_mutex> guard(resource_interfaces_lock_);
  for (const auto & interface : interface_names)
  {
    auto found_it = std::find(
      resource_storage_->available_command_interfaces_.begin(),
      resource_storage_->available_command_interfaces_.end(), interface);
    if (found_it != resource_storage_->available_command_interfaces_.end())
    {
      resource_storage_->available_command_interfaces_.erase(found_it);
      RCUTILS_LOG_DEBUG_NAMED(
        "resource_manager", "'%s' command interface removed from available list",
        interface.c_str());
    }
  }
}

// CM API: Called in "callback/slow"-thread
void ResourceManager::remove_controller_reference_interfaces(const std::string & controller_name)
{
  auto interface_names =
    resource_storage_->controllers_reference_interfaces_map_.at(controller_name);
  resource_storage_->controllers_reference_interfaces_map_.erase(controller_name);

  std::scoped_lock guard(resource_interfaces_lock_, claimed_command_interfaces_lock_);
  resource_storage_->remove_command_interfaces(interface_names);
}

// CM API: Called in "callback/slow"-thread
void ResourceManager::cache_controller_to_hardware(
  const std::string & controller_name, const std::vector<std::string> & interfaces)
{
  for (const auto & interface : interfaces)
  {
    bool found = false;
    for (const auto & [hw_name, hw_info] : resource_storage_->hardware_info_map_)
    {
      auto cmd_itf_it =
        std::find(hw_info.command_interfaces.begin(), hw_info.command_interfaces.end(), interface);
      if (cmd_itf_it != hw_info.command_interfaces.end())
      {
        found = true;
      }
      auto state_itf_it =
        std::find(hw_info.state_interfaces.begin(), hw_info.state_interfaces.end(), interface);
      if (state_itf_it != hw_info.state_interfaces.end())
      {
        found = true;
      }

      if (found)
      {
        // check if controller exist already in the list and if not add it
        auto controllers = resource_storage_->hardware_used_by_controllers_[hw_name];
        auto ctrl_it = std::find(controllers.begin(), controllers.end(), controller_name);
        if (ctrl_it == controllers.end())
        {
          // add because it does not exist
          controllers.reserve(controllers.size() + 1);
          controllers.push_back(controller_name);
        }
        resource_storage_->hardware_used_by_controllers_[hw_name] = controllers;
        break;
      }
    }
  }
}

// CM API: Called in "update"-thread
std::vector<std::string> ResourceManager::get_cached_controllers_to_hardware(
  const std::string & hardware_name)
{
  return resource_storage_->hardware_used_by_controllers_[hardware_name];
}

// CM API: Called in "update"-thread
bool ResourceManager::command_interface_is_claimed(const std::string & key) const
{
  if (!command_interface_is_available(key))
  {
    return false;
  }

  std::lock_guard<std::recursive_mutex> guard_claimed(claimed_command_interfaces_lock_);
  return resource_storage_->claimed_command_interface_map_.at(key);
}

// CM API: Called in "update"-thread
LoanedCommandInterface ResourceManager::claim_command_interface(const std::string & key)
{
  if (!command_interface_is_available(key))
  {
    throw std::runtime_error(std::string("Command interface with '") + key + "' does not exist");
  }

  std::lock_guard<std::recursive_mutex> guard_claimed(claimed_command_interfaces_lock_);
  if (command_interface_is_claimed(key))
  {
    throw std::runtime_error(
      std::string("Command interface with '") + key + "' is already claimed");
  }

  resource_storage_->claimed_command_interface_map_[key] = true;
  std::lock_guard<std::recursive_mutex> guard(resource_interfaces_lock_);
  return LoanedCommandInterface(
    resource_storage_->command_interface_map_.at(key),
    std::bind(&ResourceManager::release_command_interface, this, key));
}

// CM API: Called in "update"-thread
void ResourceManager::release_command_interface(const std::string & key)
{
  std::lock_guard<std::recursive_mutex> guard_claimed(claimed_command_interfaces_lock_);
  resource_storage_->claimed_command_interface_map_[key] = false;
}

// CM API: Called in "callback/slow"-thread
std::vector<std::string> ResourceManager::command_interface_keys() const
{
  std::vector<std::string> keys;
  std::lock_guard<std::recursive_mutex> guard(resource_interfaces_lock_);
  for (const auto & item : resource_storage_->command_interface_map_)
  {
    keys.push_back(std::get<0>(item));
  }
  return keys;
}

// CM API: Called in "update"-thread
std::vector<std::string> ResourceManager::available_command_interfaces() const
{
  std::lock_guard<std::recursive_mutex> guard(resource_interfaces_lock_);
  return resource_storage_->available_command_interfaces_;
}

// CM API: Called in "callback/slow"-thread
bool ResourceManager::command_interface_is_available(const std::string & name) const
{
  std::lock_guard<std::recursive_mutex> guard(resource_interfaces_lock_);
  return std::find(
           resource_storage_->available_command_interfaces_.begin(),
           resource_storage_->available_command_interfaces_.end(),
           name) != resource_storage_->available_command_interfaces_.end();
}

void ResourceManager::import_component(
  std::unique_ptr<ActuatorInterface> actuator, const HardwareInfo & hardware_info)
{
  std::lock_guard<std::recursive_mutex> guard(resources_lock_);
  resource_storage_->initialize_actuator(std::move(actuator), hardware_info);
  read_write_status.failed_hardware_names.reserve(
    resource_storage_->actuators_.size() + resource_storage_->sensors_.size() +
    resource_storage_->systems_.size());
}

void ResourceManager::import_component(
  std::unique_ptr<SensorInterface> sensor, const HardwareInfo & hardware_info)
{
  std::lock_guard<std::recursive_mutex> guard(resources_lock_);
  resource_storage_->initialize_sensor(std::move(sensor), hardware_info);
  read_write_status.failed_hardware_names.reserve(
    resource_storage_->actuators_.size() + resource_storage_->sensors_.size() +
    resource_storage_->systems_.size());
}

void ResourceManager::import_component(
  std::unique_ptr<SystemInterface> system, const HardwareInfo & hardware_info)
{
  std::lock_guard<std::recursive_mutex> guard(resources_lock_);
  resource_storage_->initialize_system(std::move(system), hardware_info);
  read_write_status.failed_hardware_names.reserve(
    resource_storage_->actuators_.size() + resource_storage_->sensors_.size() +
    resource_storage_->systems_.size());
}

// CM API: Called in "callback/slow"-thread
std::unordered_map<std::string, HardwareComponentInfo> ResourceManager::get_components_status()
{
  auto loop_and_get_state = [&](auto & container)
  {
    for (auto & component : container)
    {
      resource_storage_->hardware_info_map_[component.get_name()].state = component.get_state();
    }
  };

  loop_and_get_state(resource_storage_->actuators_);
  loop_and_get_state(resource_storage_->async_actuators_);
  loop_and_get_state(resource_storage_->sensors_);
  loop_and_get_state(resource_storage_->async_sensors_);
  loop_and_get_state(resource_storage_->systems_);
  loop_and_get_state(resource_storage_->async_systems_);

  return resource_storage_->hardware_info_map_;
}

// CM API: Called in "callback/slow"-thread
bool ResourceManager::prepare_command_mode_switch(
  const std::vector<std::string> & start_interfaces,
  const std::vector<std::string> & stop_interfaces)
{
  // When only broadcaster is activated then this lists are empty
  if (start_interfaces.empty() && stop_interfaces.empty())
  {
    return true;
  }

  auto interfaces_to_string = [&]()
  {
    std::stringstream ss;
    ss << "Start interfaces: " << std::endl << "[" << std::endl;
    for (const auto & start_if : start_interfaces)
    {
      ss << "  " << start_if << std::endl;
    }
    ss << "]" << std::endl;
    ss << "Stop interfaces: " << std::endl << "[" << std::endl;
    for (const auto & stop_if : stop_interfaces)
    {
      ss << "  " << stop_if << std::endl;
    }
    ss << "]" << std::endl;
    return ss.str();
  };

  // Check if interface exists
  std::stringstream ss_not_existing;
  ss_not_existing << "Not existing: " << std::endl << "[" << std::endl;
  auto check_exist = [&](const std::vector<std::string> & list_to_check)
  {
    bool all_exist = true;
    for (const auto & interface : list_to_check)
    {
      if (!command_interface_exists(interface))
      {
        all_exist = false;
        ss_not_existing << " " << interface << std::endl;
      }
    }
    return all_exist;
  };
  if (!(check_exist(start_interfaces) && check_exist(stop_interfaces)))
  {
    ss_not_existing << "]" << std::endl;
    RCUTILS_LOG_ERROR_NAMED(
      "resource_manager", "Not acceptable command interfaces combination: \n%s%s",
      interfaces_to_string().c_str(), ss_not_existing.str().c_str());
    return false;
  }

  // Check if interfaces are available
  std::stringstream ss_not_available;
  ss_not_available << "Not available: " << std::endl << "[" << std::endl;
  auto check_available = [&](const std::vector<std::string> & list_to_check)
  {
    bool all_available = true;
    for (const auto & interface : list_to_check)
    {
      if (!command_interface_is_available(interface))
      {
        all_available = false;
        ss_not_available << " " << interface << std::endl;
      }
    }
    return all_available;
  };
  if (!(check_available(start_interfaces) && check_available(stop_interfaces)))
  {
    ss_not_available << "]" << std::endl;
    RCUTILS_LOG_ERROR_NAMED(
      "resource_manager", "Not acceptable command interfaces combination: \n%s%s",
      interfaces_to_string().c_str(), ss_not_available.str().c_str());
    return false;
  }

  auto call_prepare_mode_switch =
    [&start_interfaces, &stop_interfaces, &interfaces_to_string](auto & components)
  {
    bool ret = true;
    for (auto & component : components)
    {
      if (
        component.get_state().id() == lifecycle_msgs::msg::State::PRIMARY_STATE_INACTIVE ||
        component.get_state().id() == lifecycle_msgs::msg::State::PRIMARY_STATE_ACTIVE)
      {
        if (
          return_type::OK !=
          component.prepare_command_mode_switch(start_interfaces, stop_interfaces))
        {
          RCUTILS_LOG_ERROR_NAMED(
            "resource_manager",
            "Component '%s' did not accept command interfaces combination: \n%s",
            component.get_name().c_str(), interfaces_to_string().c_str());
          ret = false;
        }
      }
    }
    return ret;
  };

  const bool actuators_result = call_prepare_mode_switch(resource_storage_->actuators_);
  const bool systems_result = call_prepare_mode_switch(resource_storage_->systems_);

  return actuators_result && systems_result;
}

// CM API: Called in "update"-thread
bool ResourceManager::perform_command_mode_switch(
  const std::vector<std::string> & start_interfaces,
  const std::vector<std::string> & stop_interfaces)
{
  // When only broadcaster is activated then this lists are empty
  if (start_interfaces.empty() && stop_interfaces.empty())
  {
    return true;
  }

  auto call_perform_mode_switch = [&start_interfaces, &stop_interfaces](auto & components)
  {
    bool ret = true;
    for (auto & component : components)
    {
      if (
        component.get_state().id() == lifecycle_msgs::msg::State::PRIMARY_STATE_INACTIVE ||
        component.get_state().id() == lifecycle_msgs::msg::State::PRIMARY_STATE_ACTIVE)
      {
        if (
          return_type::OK !=
          component.perform_command_mode_switch(start_interfaces, stop_interfaces))
        {
          RCUTILS_LOG_ERROR_NAMED(
            "resource_manager", "Component '%s' could not perform switch",
            component.get_name().c_str());
          ret = false;
        }
      }
    }
    return ret;
  };

  const bool actuators_result = call_perform_mode_switch(resource_storage_->actuators_);
  const bool systems_result = call_perform_mode_switch(resource_storage_->systems_);

  return actuators_result && systems_result;
}

// CM API: Called in "callback/slow"-thread
return_type ResourceManager::set_component_state(
  const std::string & component_name, rclcpp_lifecycle::State & target_state)
{
  using lifecycle_msgs::msg::State;
  using std::placeholders::_1;
  using std::placeholders::_2;

  auto found_it = resource_storage_->hardware_info_map_.find(component_name);

  if (found_it == resource_storage_->hardware_info_map_.end())
  {
    RCUTILS_LOG_INFO_NAMED(
      "resource_manager", "Hardware Component with name '%s' does not exists",
      component_name.c_str());
    return return_type::ERROR;
  }

  return_type result = return_type::OK;

  if (target_state.id() == 0)
  {
    if (target_state.label() == lifecycle_state_names::UNCONFIGURED)
    {
      target_state = rclcpp_lifecycle::State(
        State::PRIMARY_STATE_UNCONFIGURED, lifecycle_state_names::UNCONFIGURED);
    }
    if (target_state.label() == lifecycle_state_names::INACTIVE)
    {
      target_state =
        rclcpp_lifecycle::State(State::PRIMARY_STATE_INACTIVE, lifecycle_state_names::INACTIVE);
    }
    if (target_state.label() == lifecycle_state_names::ACTIVE)
    {
      target_state =
        rclcpp_lifecycle::State(State::PRIMARY_STATE_ACTIVE, lifecycle_state_names::ACTIVE);
    }
    if (target_state.label() == lifecycle_state_names::FINALIZED)
    {
      target_state =
        rclcpp_lifecycle::State(State::PRIMARY_STATE_FINALIZED, lifecycle_state_names::FINALIZED);
    }
  }

  auto find_set_component_state = [&](auto action, auto & components)
  {
    auto found_component_it = std::find_if(
      components.begin(), components.end(),
      [&](const auto & component) { return component.get_name() == component_name; });

    if (found_component_it != components.end())
    {
      if (action(*found_component_it, target_state))
      {
        result = return_type::OK;
      }
      else
      {
        result = return_type::ERROR;
      }
      return true;
    }
    return false;
  };

  bool found = find_set_component_state(
    std::bind(&ResourceStorage::set_component_state<Actuator>, resource_storage_.get(), _1, _2),
    resource_storage_->actuators_);
  if (!found)
  {
    found = find_set_component_state(
      std::bind(&ResourceStorage::set_component_state<Sensor>, resource_storage_.get(), _1, _2),
      resource_storage_->sensors_);
  }
  if (!found)
  {
    found = find_set_component_state(
      std::bind(&ResourceStorage::set_component_state<System>, resource_storage_.get(), _1, _2),
      resource_storage_->systems_);
  }
  if (!found)
  {
    found = find_set_component_state(
      std::bind(&ResourceStorage::set_component_state<Actuator>, resource_storage_.get(), _1, _2),
      resource_storage_->async_actuators_);
  }
  if (!found)
  {
    found = find_set_component_state(
      std::bind(&ResourceStorage::set_component_state<System>, resource_storage_.get(), _1, _2),
      resource_storage_->async_systems_);
  }
  if (!found)
  {
    found = find_set_component_state(
      std::bind(&ResourceStorage::set_component_state<Sensor>, resource_storage_.get(), _1, _2),
      resource_storage_->async_sensors_);
  }

  return result;
}

// CM API: Called in "update"-thread
HardwareReadWriteStatus ResourceManager::read(
  const rclcpp::Time & time, const rclcpp::Duration & period)
{
  std::lock_guard<std::recursive_mutex> guard(resources_lock_);
  read_write_status.ok = true;
  read_write_status.failed_hardware_names.clear();

  auto read_components = [&](auto & components)
  {
    for (auto & component : components)
    {
      auto ret_val = component.read(time, period);
      if (ret_val == return_type::ERROR)
      {
        read_write_status.ok = false;
        read_write_status.failed_hardware_names.push_back(component.get_name());
        resource_storage_->remove_all_hardware_interfaces_from_available_list(component.get_name());
      }
      else if (ret_val == return_type::DEACTIVATE)
      {
        resource_storage_->deactivate_hardware(component);
      }
      // If desired: automatic re-activation. We could add a flag for this...
      // else
      // {
      // using lifecycle_msgs::msg::State;
      // rclcpp_lifecycle::State state(State::PRIMARY_STATE_ACTIVE, lifecycle_state_names::ACTIVE);
      // set_component_state(component.get_name(), state);
      // }
    }
  };

  read_components(resource_storage_->actuators_);
  read_components(resource_storage_->sensors_);
  read_components(resource_storage_->systems_);

  return read_write_status;
}

// CM API: Called in "update"-thread
HardwareReadWriteStatus ResourceManager::write(
  const rclcpp::Time & time, const rclcpp::Duration & period)
{
  std::lock_guard<std::recursive_mutex> guard(resources_lock_);
  read_write_status.ok = true;
  read_write_status.failed_hardware_names.clear();

  auto write_components = [&](auto & components)
  {
    for (auto & component : components)
    {
      auto ret_val = component.write(time, period);
      if (ret_val == return_type::ERROR)
      {
        read_write_status.ok = false;
        read_write_status.failed_hardware_names.push_back(component.get_name());
        resource_storage_->remove_all_hardware_interfaces_from_available_list(component.get_name());
      }
      else if (ret_val == return_type::DEACTIVATE)
      {
        resource_storage_->deactivate_hardware(component);
      }
    }
  };

  write_components(resource_storage_->actuators_);
  write_components(resource_storage_->systems_);

  return read_write_status;
}

// BEGIN: "used only in tests and locally"
size_t ResourceManager::actuator_components_size() const
{
  return resource_storage_->actuators_.size();
}

size_t ResourceManager::sensor_components_size() const
{
  return resource_storage_->sensors_.size();
}

size_t ResourceManager::system_components_size() const
{
  return resource_storage_->systems_.size();
}

bool ResourceManager::command_interface_exists(const std::string & key) const
{
  std::lock_guard<std::recursive_mutex> guard(resource_interfaces_lock_);
  return resource_storage_->command_interface_map_.find(key) !=
         resource_storage_->command_interface_map_.end();
}

bool ResourceManager::state_interface_exists(const std::string & key) const
{
  std::lock_guard<std::recursive_mutex> guard(resource_interfaces_lock_);
  return resource_storage_->state_interface_map_.find(key) !=
         resource_storage_->state_interface_map_.end();
}

// END: "used only in tests and locally"

// BEGIN: private methods

void ResourceManager::validate_storage(
  const std::vector<hardware_interface::HardwareInfo> & hardware_info) const
{
  std::vector<std::string> missing_state_keys = {};
  std::vector<std::string> missing_command_keys = {};

  for (const auto & hardware : hardware_info)
  {
    for (const auto & joint : hardware.joints)
    {
      for (const auto & state_interface : joint.state_interfaces)
      {
        if (!state_interface_exists(joint.name + "/" + state_interface.name))
        {
          missing_state_keys.emplace_back(joint.name + "/" + state_interface.name);
        }
      }
      for (const auto & command_interface : joint.command_interfaces)
      {
        if (!command_interface_exists(joint.name + "/" + command_interface.name))
        {
          missing_command_keys.emplace_back(joint.name + "/" + command_interface.name);
        }
      }
    }
    for (const auto & sensor : hardware.sensors)
    {
      for (const auto & state_interface : sensor.state_interfaces)
      {
        if (!state_interface_exists(sensor.name + "/" + state_interface.name))
        {
          missing_state_keys.emplace_back(sensor.name + "/" + state_interface.name);
        }
      }
    }
    for (const auto & gpio : hardware.gpios)
    {
      for (const auto & state_interface : gpio.state_interfaces)
      {
        if (!state_interface_exists(gpio.name + "/" + state_interface.name))
        {
          missing_state_keys.emplace_back(gpio.name + "/" + state_interface.name);
        }
      }
      for (const auto & command_interface : gpio.command_interfaces)
      {
        if (!command_interface_exists(gpio.name + "/" + command_interface.name))
        {
          missing_command_keys.emplace_back(gpio.name + "/" + command_interface.name);
        }
      }
    }
  }

  if (!missing_state_keys.empty() || !missing_command_keys.empty())
  {
    std::string err_msg = "Wrong state or command interface configuration.\n";
    err_msg += "missing state interfaces:\n";
    for (const auto & missing_key : missing_state_keys)
    {
      err_msg += "' " + missing_key + " '" + "\t";
    }
    err_msg += "\nmissing command interfaces:\n";
    for (const auto & missing_key : missing_command_keys)
    {
      err_msg += "' " + missing_key + " '" + "\t";
    }

    throw std::runtime_error(err_msg);
  }
}

// END: private methods

}  // namespace hardware_interface