executor.hpp

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// Copyright 2014 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__EXECUTOR_HPP_
#define RCLCPP__EXECUTOR_HPP_

#include <algorithm>
#include <cassert>
#include <chrono>
#include <cstdlib>
#include <iostream>
#include <list>
#include <memory>
#include <mutex>
#include <string>
#include <vector>

#include "rcl/guard_condition.h"
#include "rcl/wait.h"

#include "rclcpp/contexts/default_context.hpp"
#include "rclcpp/memory_strategies.hpp"
#include "rclcpp/memory_strategy.hpp"
#include "rclcpp/node_interfaces/node_base_interface.hpp"
#include "rclcpp/utilities.hpp"
#include "rclcpp/visibility_control.hpp"

namespace rclcpp
{

// Forward declaration is used in convenience method signature.
class Node;

namespace executor
{


enum class FutureReturnCode {SUCCESS, INTERRUPTED, TIMEOUT};

RCLCPP_PUBLIC
std::ostream &
operator<<(std::ostream & os, const FutureReturnCode & future_return_code);

RCLCPP_PUBLIC
std::string
to_string(const FutureReturnCode & future_return_code);


struct ExecutorArgs
{
  ExecutorArgs()
  : memory_strategy(memory_strategies::create_default_strategy()),
    context(rclcpp::contexts::default_context::get_global_default_context()),
    max_conditions(0)
  {}

  memory_strategy::MemoryStrategy::SharedPtr memory_strategy;
  std::shared_ptr<rclcpp::Context> context;
  size_t max_conditions;
};

static inline ExecutorArgs create_default_executor_arguments()
{
  return ExecutorArgs();
}


class Executor
{
public:
  RCLCPP_SMART_PTR_DEFINITIONS_NOT_COPYABLE(Executor)

  
  // \param[in] ms The memory strategy to be used with this executor.
  RCLCPP_PUBLIC
  explicit Executor(const ExecutorArgs & args = ExecutorArgs());

  RCLCPP_PUBLIC
  virtual ~Executor();

  // It is up to the implementation of Executor to implement spin.
  virtual void
  spin() = 0;


  RCLCPP_PUBLIC
  virtual void
  add_node(rclcpp::node_interfaces::NodeBaseInterface::SharedPtr node_ptr, bool notify = true);

  RCLCPP_PUBLIC
  virtual void
  add_node(std::shared_ptr<rclcpp::Node> node_ptr, bool notify = true);


  RCLCPP_PUBLIC
  virtual void
  remove_node(rclcpp::node_interfaces::NodeBaseInterface::SharedPtr node_ptr, bool notify = true);

  RCLCPP_PUBLIC
  virtual void
  remove_node(std::shared_ptr<rclcpp::Node> node_ptr, bool notify = true);


  template<typename RepT = int64_t, typename T = std::milli>
  void
  spin_node_once(
    rclcpp::node_interfaces::NodeBaseInterface::SharedPtr node,
    std::chrono::duration<RepT, T> timeout = std::chrono::duration<RepT, T>(-1))
  {
    return spin_node_once_nanoseconds(
      node,
      std::chrono::duration_cast<std::chrono::nanoseconds>(timeout)
    );
  }

  template<typename NodeT = rclcpp::Node, typename RepT = int64_t, typename T = std::milli>
  void
  spin_node_once(
    std::shared_ptr<NodeT> node,
    std::chrono::duration<RepT, T> timeout = std::chrono::duration<RepT, T>(-1))
  {
    return spin_node_once_nanoseconds(
      node->get_node_base_interface(),
      std::chrono::duration_cast<std::chrono::nanoseconds>(timeout)
    );
  }


  RCLCPP_PUBLIC
  void
  spin_node_some(rclcpp::node_interfaces::NodeBaseInterface::SharedPtr node);

  RCLCPP_PUBLIC
  void
  spin_node_some(std::shared_ptr<rclcpp::Node> node);


  RCLCPP_PUBLIC
  virtual void
  spin_some(std::chrono::nanoseconds max_duration = std::chrono::nanoseconds(0));

  RCLCPP_PUBLIC
  virtual void
  spin_once(std::chrono::nanoseconds timeout = std::chrono::nanoseconds(-1));


  template<typename ResponseT, typename TimeRepT = int64_t, typename TimeT = std::milli>
  FutureReturnCode
  spin_until_future_complete(
    std::shared_future<ResponseT> & future,
    std::chrono::duration<TimeRepT, TimeT> timeout = std::chrono::duration<TimeRepT, TimeT>(-1))
  {
    // TODO(wjwwood): does not work recursively; can't call spin_node_until_future_complete
    // inside a callback executed by an executor.

    // Check the future before entering the while loop.
    // If the future is already complete, don't try to spin.
    std::future_status status = future.wait_for(std::chrono::seconds(0));
    if (status == std::future_status::ready) {
      return FutureReturnCode::SUCCESS;
    }

    auto end_time = std::chrono::steady_clock::now();
    std::chrono::nanoseconds timeout_ns = std::chrono::duration_cast<std::chrono::nanoseconds>(
      timeout);
    if (timeout_ns > std::chrono::nanoseconds::zero()) {
      end_time += timeout_ns;
    }
    std::chrono::nanoseconds timeout_left = timeout_ns;

    while (rclcpp::ok(this->context_)) {
      // Do one item of work.
      spin_once(timeout_left);
      // Check if the future is set, return SUCCESS if it is.
      status = future.wait_for(std::chrono::seconds(0));
      if (status == std::future_status::ready) {
        return FutureReturnCode::SUCCESS;
      }
      // If the original timeout is < 0, then this is blocking, never TIMEOUT.
      if (timeout_ns < std::chrono::nanoseconds::zero()) {
        continue;
      }
      // Otherwise check if we still have time to wait, return TIMEOUT if not.
      auto now = std::chrono::steady_clock::now();
      if (now >= end_time) {
        return FutureReturnCode::TIMEOUT;
      }
      // Subtract the elapsed time from the original timeout.
      timeout_left = std::chrono::duration_cast<std::chrono::nanoseconds>(end_time - now);
    }

    // The future did not complete before ok() returned false, return INTERRUPTED.
    return FutureReturnCode::INTERRUPTED;
  }

  /* This function can be called asynchonously from any thread. */
  RCLCPP_PUBLIC
  void
  cancel();


  RCLCPP_PUBLIC
  void
  set_memory_strategy(memory_strategy::MemoryStrategy::SharedPtr memory_strategy);

protected:
  RCLCPP_PUBLIC
  void
  spin_node_once_nanoseconds(
    rclcpp::node_interfaces::NodeBaseInterface::SharedPtr node,
    std::chrono::nanoseconds timeout);


  RCLCPP_PUBLIC
  void
  execute_any_executable(AnyExecutable & any_exec);

  RCLCPP_PUBLIC
  static void
  execute_subscription(
    rclcpp::SubscriptionBase::SharedPtr subscription);

  RCLCPP_PUBLIC
  static void
  execute_timer(rclcpp::TimerBase::SharedPtr timer);

  RCLCPP_PUBLIC
  static void
  execute_service(rclcpp::ServiceBase::SharedPtr service);

  RCLCPP_PUBLIC
  static void
  execute_client(rclcpp::ClientBase::SharedPtr client);

  RCLCPP_PUBLIC
  void
  wait_for_work(std::chrono::nanoseconds timeout = std::chrono::nanoseconds(-1));

  RCLCPP_PUBLIC
  rclcpp::node_interfaces::NodeBaseInterface::SharedPtr
  get_node_by_group(rclcpp::callback_group::CallbackGroup::SharedPtr group);

  RCLCPP_PUBLIC
  rclcpp::callback_group::CallbackGroup::SharedPtr
  get_group_by_timer(rclcpp::TimerBase::SharedPtr timer);

  RCLCPP_PUBLIC
  bool
  get_next_ready_executable(AnyExecutable & any_executable);

  RCLCPP_PUBLIC
  bool
  get_next_executable(
    AnyExecutable & any_executable,
    std::chrono::nanoseconds timeout = std::chrono::nanoseconds(-1));

  std::atomic_bool spinning;

  rcl_guard_condition_t interrupt_guard_condition_ = rcl_get_zero_initialized_guard_condition();

  rcl_wait_set_t wait_set_ = rcl_get_zero_initialized_wait_set();

  // Mutex to protect the subsequent memory_strategy_.
  std::mutex memory_strategy_mutex_;

  memory_strategy::MemoryStrategy::SharedPtr memory_strategy_;

  std::shared_ptr<rclcpp::Context> context_;

private:
  RCLCPP_DISABLE_COPY(Executor)

  std::list<rclcpp::node_interfaces::NodeBaseInterface::WeakPtr> weak_nodes_;
  std::list<const rcl_guard_condition_t *> guard_conditions_;
};

}  // namespace executor
}  // namespace rclcpp

#endif  // RCLCPP__EXECUTOR_HPP_