/*
 * Copyright (c) Meta Platforms, Inc. and affiliates.
 *
 * 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 _THRIFT_CONCURRENCY_TIMERMANAGER_H_
#define _THRIFT_CONCURRENCY_TIMERMANAGER_H_ 1

#include <atomic>
#include <condition_variable>
#include <ctime>
#include <map>
#include <memory>
#include <mutex>

#include <thrift/lib/cpp/concurrency/Exception.h>
#include <thrift/lib/cpp/concurrency/Thread.h>

namespace apache {
namespace thrift {
namespace concurrency {

/**
 * Timer Manager
 *
 * This class dispatches timer tasks when they fall due.
 *
 * @version $Id:$
 */
class TimerManager {
 public:
  TimerManager();

  virtual ~TimerManager();

  virtual std::shared_ptr<const ThreadFactory> threadFactory() const;

  virtual void threadFactory(std::shared_ptr<const ThreadFactory> value);

  /**
   * Starts the timer manager service
   *
   * @throws IllegalArgumentException Missing thread factory attribute
   */
  virtual void start();

  /**
   * Stops the timer manager service
   */
  virtual void stop();

  virtual size_t taskCount() const;

  /**
   * Adds a task to be executed at some time in the future by a worker thread.
   *
   * @param task The task to execute
   * @param timeout Time in milliseconds to delay before executing task
   */
  virtual void add(std::shared_ptr<Runnable> task, int64_t timeout);

  /**
   * Adds a task to be executed at some time in the future by a worker thread.
   *
   * @param task The task to execute
   * @param timeout Absolute time in the future to execute task.
   */
  virtual void add(
      std::shared_ptr<Runnable> task, const struct timespec& timeout);

  /**
   * Removes a pending task
   *
   * @throws NoSuchTaskException Specified task doesn't exist. It was either
   *                             processed already or this call was made for a
   *                             task that was never added to this timer
   *
   * @throws UncancellableTaskException Specified task is already being
   *                                    executed or has completed execution.
   */
  virtual void remove(std::shared_ptr<Runnable> task);

  enum STATE {
    UNINITIALIZED,
    STARTING,
    STARTED,
    STOPPING,
    STOPPED,
  };

  virtual STATE state() const;

 private:
  std::shared_ptr<const ThreadFactory> threadFactory_;
  class Task;
  friend class Task;
  std::multimap<int64_t, std::shared_ptr<Task>> taskMap_;
  std::atomic<size_t> taskCount_;
  mutable std::mutex mutex_;
  std::condition_variable cond_;
  STATE state_;
  class Dispatcher;
  friend class Dispatcher;
  std::shared_ptr<Dispatcher> dispatcher_;
  std::shared_ptr<Thread> dispatcherThread_;
  typedef std::multimap<int64_t, std::shared_ptr<TimerManager::Task>>::iterator
      task_iterator;
  typedef std::pair<task_iterator, task_iterator> task_range;
};

} // namespace concurrency
} // namespace thrift
} // namespace apache

#endif // #ifndef _THRIFT_CONCURRENCY_TIMERMANAGER_H_