/*

 * H.265 video codec.

 * Copyright (c) 2013-2014 struktur AG, Dirk Farin <farin@struktur.de>

 *

 * This file is part of libde265.

 *

 * libde265 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.

 *

 * libde265 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 a copy of the GNU Lesser General Public License

 * along with libde265.  If not, see <http://www.gnu.org/licenses/>.

 */

#ifndef DE265_THREADS_H

#define DE265_THREADS_H

#include "libde265/de265.h"

#ifdef HAVE_CONFIG_H

#include "config.h"

#endif

#include <deque>

#include <string>

#include <atomic>

#ifdef _WIN32

#if !defined(NOMINMAX)

#define NOMINMAX

#endif

#include <windows.h>

#include "../extra/win32cond.h"

#if _MSC_VER > 1310

#include <intrin.h>

#endif

#endif  // _WIN32

#include <atomic>

#include <mutex>

#include <condition_variable>

#include <thread>

class de265_progress_lock

{

public:

  de265_progress_lock();

  ~de265_progress_lock();

  void wait_for_progress(int progress);

  void set_progress(int progress);

  void increase_progress(int progress);

  int  get_progress() const;

  void reset(int value=0) { mProgress.store(value, std::memory_order_release); }

private:

  // Read lock-free on the fast paths of wait_for_progress()/get_progress()

  // while written under 'mutex'. It must be atomic so those reads are not a

  // data race, and it carries acquire/release ordering so that the state a

  // producer wrote before signalling progress (e.g. the saved WPP row context)

  // is published to a consumer that observes the progress value without taking

  // the mutex (GHSA-xp3h-6f5r-8cxp).

  std::atomic<int> mProgress;

  // private data

  std::mutex mutex;

  std::condition_variable cond;

};

class thread_task

{

public:

  thread_task() : state(Queued) { }

  virtual ~thread_task() { }

  enum { Queued, Running, Blocked, Finished } state;

  virtual void work() = 0;

  virtual std::string name() const { return "noname"; }

};

constexpr int MAX_THREADS = 32;

/* TODO NOTE: When unblocking a task, we have to check first

   if there are threads waiting because of the run-count limit.

   If there are higher-priority tasks, those should be run instead

   of the just unblocked task.

 */

class thread_pool

{

 public:

  de265_error start(int num_threads);

  void        stop(); // do not process remaining tasks

  void        add_task(thread_task* task);

  bool stopped;

  std::deque<thread_task*> tasks;  // we are not the owner

  int num_threads_working;

  std::mutex  mutex;

  std::condition_variable  cond_var;

private:

  std::thread thread[MAX_THREADS];

  int num_threads;

  //int ctbx[MAX_THREADS]; // the CTB the thread is working on

  //int ctby[MAX_THREADS];

};

#endif