scheduler.hpp

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/* -*- Mode:C++; c-file-style:"gnu"; indent-tabs-mode:nil; -*- */
/*
 * Copyright (c) 2013-2024 Regents of the University of California.
 *
 * This file is part of ndn-cxx library (NDN C++ library with eXperimental eXtensions).
 *
 * ndn-cxx library is free software: you can redistribute it and/or modify it under the
 * terms of the GNU Lesser General Public License as published by the Free Software
 * Foundation, either version 3 of the License, or (at your option) any later version.
 *
 * ndn-cxx library is distributed in the hope that it will be useful, but WITHOUT ANY
 * WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR A
 * PARTICULAR PURPOSE.  See the GNU Lesser General Public License for more details.
 *
 * You should have received copies of the GNU General Public License and GNU Lesser
 * General Public License along with ndn-cxx, e.g., in COPYING.md file.  If not, see
 * <http://www.gnu.org/licenses/>.
 *
 * See AUTHORS.md for complete list of ndn-cxx authors and contributors.
 */
 
#ifndef NDN_CXX_UTIL_SCHEDULER_HPP
#define NDN_CXX_UTIL_SCHEDULER_HPP
 
#include "ndn-cxx/detail/asio-fwd.hpp"
#include "ndn-cxx/detail/cancel-handle.hpp"
#include "ndn-cxx/detail/common.hpp"
#include "ndn-cxx/util/time.hpp"
 
#include <boost/operators.hpp>
#include <boost/system/error_code.hpp>
 
#include <set>
 
namespace ndn {
 
namespace detail {
class SteadyTimer;
} // namespace detail
 
namespace scheduler {
 
class Scheduler;
struct EventInfo;
 
using EventCallback = std::function<void()>;
 
class EventId : public detail::CancelHandle, private boost::equality_comparable<EventId>
{
public:
  EventId() noexcept = default;
 
  explicit
  operator bool() const noexcept;
 
  void
  reset() noexcept;
 
private:
  EventId(Scheduler& sched, weak_ptr<EventInfo> info);
 
private: // non-member operators
  // NOTE: the following "hidden friend" operators are available via
  //       argument-dependent lookup only and must be defined inline.
  // boost::equality_comparable provides != operator.
 
  friend bool
  operator==(const EventId& lhs, const EventId& rhs) noexcept
  {
    return (!lhs && !rhs) ||
        (!lhs.m_info.owner_before(rhs.m_info) &&
         !rhs.m_info.owner_before(lhs.m_info));
  }
 
  friend std::ostream&
  operator<<(std::ostream& os, const EventId& eventId)
  {
    return os << eventId.m_info.lock();
  }
 
private:
  weak_ptr<EventInfo> m_info;
 
  friend Scheduler;
};
 
using ScopedEventId = detail::ScopedCancelHandle<EventId>;
 
class Scheduler : noncopyable
{
public:
  explicit
  Scheduler(boost::asio::io_context& ioCtx);
 
  ~Scheduler();
 
  EventId
  schedule(time::nanoseconds after, EventCallback callback);
 
  void
  cancelAllEvents();
 
private:
  void
  cancelImpl(const shared_ptr<EventInfo>& info);
 
  void
  scheduleNext();
 
  void
  executeEvent(const boost::system::error_code& code);
 
private:
  class EventQueueCompare
  {
  public:
    bool
    operator()(const shared_ptr<EventInfo>& a, const shared_ptr<EventInfo>& b) const noexcept;
  };
 
  using EventQueue = std::multiset<shared_ptr<EventInfo>, EventQueueCompare>;
  EventQueue m_queue;
 
  unique_ptr<detail::SteadyTimer> m_timer;
  bool m_isEventExecuting = false;
 
  friend EventId;
  friend EventInfo;
};
 
} // namespace scheduler
 
using scheduler::Scheduler;
 
} // namespace ndn
 
#endif // NDN_CXX_UTIL_SCHEDULER_HPP