delay_node.h

/*  Copyright (C) 2018-2025 Davide Faconti -  All Rights Reserved
*
*   Permission is hereby granted, free of charge, to any person obtaining a copy of this software and associated documentation files (the "Software"),
*   to deal in the Software without restriction, including without limitation the rights to use, copy, modify, merge, publish, distribute, sublicense,
*   and/or sell copies of the Software, and to permit persons to whom the Software is furnished to do so, subject to the following conditions:
*   The above copyright notice and this permission notice shall be included in all copies or substantial portions of the Software.
*
*   THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
*   FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY,
*   WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
*/
 
#pragma once
 
#include "behaviortree_cpp/decorator_node.h"
#include "behaviortree_cpp/utils/timer_queue.h"
 
#include <atomic>
 
namespace BT
{
/**
 * @brief The delay node will introduce a delay and then tick the
 * child returning the status of the child as it is upon completion
 * The delay is in milliseconds and it is passed using the port "delay_msec".
 *
 * During the delay the node changes status to RUNNING
 *
 * Example:
 *
 * <Delay delay_msec="5000">
 *    <KeepYourBreath/>
 * </Delay>
 */
class DelayNode : public DecoratorNode
{
public:
  DelayNode(const std::string& name, unsigned milliseconds);
 
  DelayNode(const std::string& name, const NodeConfig& config);
 
  ~DelayNode() override
  {
    // Only stop the timer thread here; do NOT call halt(). During tree
    // destruction the child node may already be gone: nodes are owned by a
    // flat std::vector<TreeNode::Ptr> whose element-destruction order is
    // unspecified (libstdc++ tears down front-to-back, libc++ back-to-front),
    // so the child can outlive or predecease this decorator. halt() ->
    // DecoratorNode::halt() -> resetChild() dereferences that child and
    // segfaults on libc++ (macOS). This mirrors TimeoutNode's destructor.
    timer_.cancelAll();
  }
 
  DelayNode(const DelayNode&) = delete;
  DelayNode& operator=(const DelayNode&) = delete;
  DelayNode(DelayNode&&) = delete;
  DelayNode& operator=(DelayNode&&) = delete;
 
  static PortsList providedPorts()
  {
    return { InputPort<unsigned>("delay_msec", "Tick the child after a few "
                                               "milliseconds") };
  }
 
  void halt() override;
 
private:
  TimerQueue<> timer_;
  uint64_t timer_id_;
 
  virtual BT::NodeStatus tick() override;
 
  bool delay_started_ = false;
  std::atomic_bool delay_complete_ = false;
  bool delay_aborted_ = false;
  unsigned msec_;
  bool read_parameter_from_ports_;
  std::mutex delay_mutex_;
};
 
}  // namespace BT