Program Listing for File create_timer.hpp

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// Copyright 2019 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.

#ifndef RCLCPP__CREATE_TIMER_HPP_
#define RCLCPP__CREATE_TIMER_HPP_

#include <chrono>
#include <exception>
#include <memory>
#include <string>
#include <utility>

#include "rclcpp/duration.hpp"
#include "rclcpp/node_interfaces/get_node_base_interface.hpp"
#include "rclcpp/node_interfaces/get_node_timers_interface.hpp"
#include "rclcpp/node_interfaces/node_base_interface.hpp"
#include "rclcpp/node_interfaces/node_timers_interface.hpp"

namespace rclcpp
{
template<typename CallbackT>
typename rclcpp::TimerBase::SharedPtr
create_timer(
  std::shared_ptr<node_interfaces::NodeBaseInterface> node_base,
  std::shared_ptr<node_interfaces::NodeTimersInterface> node_timers,
  rclcpp::Clock::SharedPtr clock,
  rclcpp::Duration period,
  CallbackT && callback,
  rclcpp::CallbackGroup::SharedPtr group = nullptr)
{
  auto timer = rclcpp::GenericTimer<CallbackT>::make_shared(
    clock,
    period.to_chrono<std::chrono::nanoseconds>(),
    std::forward<CallbackT>(callback),
    node_base->get_context());

  node_timers->add_timer(timer, group);
  return timer;
}

template<typename NodeT, typename CallbackT>
typename rclcpp::TimerBase::SharedPtr
create_timer(
  NodeT node,
  rclcpp::Clock::SharedPtr clock,
  rclcpp::Duration period,
  CallbackT && callback,
  rclcpp::CallbackGroup::SharedPtr group = nullptr)
{
  return create_timer(
    rclcpp::node_interfaces::get_node_base_interface(node),
    rclcpp::node_interfaces::get_node_timers_interface(node),
    clock,
    period,
    std::forward<CallbackT>(callback),
    group);
}


template<typename DurationRepT, typename DurationT, typename CallbackT>
typename rclcpp::WallTimer<CallbackT>::SharedPtr
create_wall_timer(
  std::chrono::duration<DurationRepT, DurationT> period,
  CallbackT callback,
  rclcpp::CallbackGroup::SharedPtr group,
  node_interfaces::NodeBaseInterface * node_base,
  node_interfaces::NodeTimersInterface * node_timers)
{
  if (node_base == nullptr) {
    throw std::invalid_argument{"input node_base cannot be null"};
  }

  if (node_timers == nullptr) {
    throw std::invalid_argument{"input node_timers cannot be null"};
  }

  if (period < std::chrono::duration<DurationRepT, DurationT>::zero()) {
    throw std::invalid_argument{"timer period cannot be negative"};
  }

  // Casting to a double representation might lose precision and allow the check below to succeed
  // but the actual cast to nanoseconds fail. Using 1 DurationT worth of nanoseconds less than max.
  constexpr auto maximum_safe_cast_ns =
    std::chrono::nanoseconds::max() - std::chrono::duration<DurationRepT, DurationT>(1);

  // If period is greater than nanoseconds::max(), the duration_cast to nanoseconds will overflow
  // a signed integer, which is undefined behavior. Checking whether any std::chrono::duration is
  // greater than nanoseconds::max() is a difficult general problem. This is a more conservative
  // version of Howard Hinnant's (the <chrono> guy>) response here:
  // https://stackoverflow.com/a/44637334/2089061
  // However, this doesn't solve the issue for all possible duration types of period.
  // Follow-up issue: https://github.com/ros2/rclcpp/issues/1177
  constexpr auto ns_max_as_double =
    std::chrono::duration_cast<std::chrono::duration<double, std::chrono::nanoseconds::period>>(
    maximum_safe_cast_ns);
  if (period > ns_max_as_double) {
    throw std::invalid_argument{
            "timer period must be less than std::chrono::nanoseconds::max()"};
  }

  const auto period_ns = std::chrono::duration_cast<std::chrono::nanoseconds>(period);
  if (period_ns < std::chrono::nanoseconds::zero()) {
    throw std::runtime_error{
            "Casting timer period to nanoseconds resulted in integer overflow."};
  }

  auto timer = rclcpp::WallTimer<CallbackT>::make_shared(
    period_ns, std::move(callback), node_base->get_context());
  node_timers->add_timer(timer, group);
  return timer;
}

}  // namespace rclcpp

#endif  // RCLCPP__CREATE_TIMER_HPP_