// <thread> -*- C++ -*-

// Copyright (C) 2008-2020 Free Software Foundation, Inc.
//
// This file is part of the GNU ISO C++ Library.  This library is free
// software; you can redistribute it and/or modify it under the
// terms of the GNU General Public License as published by the
// Free Software Foundation; either version 3, or (at your option)
// any later version.

// This 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 General Public License for more details.

// Under Section 7 of GPL version 3, you are granted additional
// permissions described in the GCC Runtime Library Exception, version
// 3.1, as published by the Free Software Foundation.

// You should have received a copy of the GNU General Public License and
// a copy of the GCC Runtime Library Exception along with this program;
// see the files COPYING3 and COPYING.RUNTIME respectively.  If not, see
// <http://www.gnu.org/licenses/>.

/** @file include/thread
 *  This is a Standard C++ Library header.
 */

#ifndef _GLIBCXX_THREAD
#define _GLIBCXX_THREAD 1

#pragma GCC system_header

#if __cplusplus < 201103L
# include <bits/c++0x_warning.h>
#else

#include <chrono> // std::chrono::*

#if __cplusplus > 201703L
# include <compare>	// std::strong_ordering
# include <stop_token>	// std::stop_source, std::stop_token, std::nostopstate
#endif

#include <bits/std_thread.h> // std::thread, get_id, yield
#include <bits/functional_hash.h> // std::hash

#ifdef _GLIBCXX_USE_NANOSLEEP
# include <cerrno>  // errno, EINTR
# include <time.h>  // nanosleep
#endif

namespace std _GLIBCXX_VISIBILITY(default)
{
_GLIBCXX_BEGIN_NAMESPACE_VERSION

  /**
   * @defgroup threads Threads
   * @ingroup concurrency
   *
   * Classes for thread support.
   * @{
   */

  // std::thread is defined in <bits/std_thread.h>

#if __cpp_lib_three_way_comparison
  inline strong_ordering
  operator<=>(thread::id __x, thread::id __y) noexcept
  { return __x._M_thread <=> __y._M_thread; }
#else
  inline bool
  operator!=(thread::id __x, thread::id __y) noexcept
  { return !(__x == __y); }

  inline bool
  operator<(thread::id __x, thread::id __y) noexcept
  {
    // Pthreads doesn't define any way to do this, so we just have to
    // assume native_handle_type is LessThanComparable.
    return __x._M_thread < __y._M_thread;
  }

  inline bool
  operator<=(thread::id __x, thread::id __y) noexcept
  { return !(__y < __x); }

  inline bool
  operator>(thread::id __x, thread::id __y) noexcept
  { return __y < __x; }

  inline bool
  operator>=(thread::id __x, thread::id __y) noexcept
  { return !(__x < __y); }
#endif // __cpp_lib_three_way_comparison

  // DR 889.
  /// std::hash specialization for thread::id.
  template<>
    struct hash<thread::id>
    : public __hash_base<size_t, thread::id>
    {
      size_t
      operator()(const thread::id& __id) const noexcept
      { return std::_Hash_impl::hash(__id._M_thread); }
    };

  template<class _CharT, class _Traits>
    inline basic_ostream<_CharT, _Traits>&
    operator<<(basic_ostream<_CharT, _Traits>& __out, thread::id __id)
    {
      if (__id == thread::id())
	return __out << "thread::id of a non-executing thread";
      else
	return __out << __id._M_thread;
    }

  /** @namespace std::this_thread
   *  @brief ISO C++ 2011 namespace for interacting with the current thread
   *
   *  C++11 30.3.2 [thread.thread.this] Namespace this_thread.
   */
  namespace this_thread
  {
#ifndef _GLIBCXX_NO_SLEEP

#ifndef _GLIBCXX_USE_NANOSLEEP
    void
    __sleep_for(chrono::seconds, chrono::nanoseconds);
#endif

    /// this_thread::sleep_for
    template<typename _Rep, typename _Period>
      inline void
      sleep_for(const chrono::duration<_Rep, _Period>& __rtime)
      {
	if (__rtime <= __rtime.zero())
	  return;
	auto __s = chrono::duration_cast<chrono::seconds>(__rtime);
	auto __ns = chrono::duration_cast<chrono::nanoseconds>(__rtime - __s);
#ifdef _GLIBCXX_USE_NANOSLEEP
	struct ::timespec __ts =
	  {
	    static_cast<std::time_t>(__s.count()),
	    static_cast<long>(__ns.count())
	  };
	while (::nanosleep(&__ts, &__ts) == -1 && errno == EINTR)
	  { }
#else
	__sleep_for(__s, __ns);
#endif
      }

    /// this_thread::sleep_until
    template<typename _Clock, typename _Duration>
      inline void
      sleep_until(const chrono::time_point<_Clock, _Duration>& __atime)
      {
#if __cplusplus > 201703L
	static_assert(chrono::is_clock_v<_Clock>);
#endif
	auto __now = _Clock::now();
	if (_Clock::is_steady)
	  {
	    if (__now < __atime)
	      sleep_for(__atime - __now);
	    return;
	  }
	while (__now < __atime)
	  {
	    sleep_for(__atime - __now);
	    __now = _Clock::now();
	  }
      }
  } // namespace this_thread
#endif // ! NO_SLEEP

#ifdef __cpp_lib_jthread

  /// A thread that can be requested to stop and automatically joined.
  class jthread
  {
  public:
    using id = thread::id;
    using native_handle_type = thread::native_handle_type;

    jthread() noexcept
    : _M_stop_source{nostopstate}
    { }

    template<typename _Callable, typename... _Args,
	     typename = enable_if_t<!is_same_v<remove_cvref_t<_Callable>,
					       jthread>>>
      explicit
      jthread(_Callable&& __f, _Args&&... __args)
      : _M_thread{_S_create(_M_stop_source, std::forward<_Callable>(__f),
			    std::forward<_Args>(__args)...)}
      { }

    jthread(const jthread&) = delete;
    jthread(jthread&&) noexcept = default;

    ~jthread()
    {
      if (joinable())
        {
          request_stop();
          join();
        }
    }

    jthread&
    operator=(const jthread&) = delete;

    jthread&
    operator=(jthread&& __other) noexcept
    {
      std::jthread(std::move(__other)).swap(*this);
      return *this;
    }

    void
    swap(jthread& __other) noexcept
    {
      std::swap(_M_stop_source, __other._M_stop_source);
      std::swap(_M_thread, __other._M_thread);
    }

    [[nodiscard]] bool
    joinable() const noexcept
    {
      return _M_thread.joinable();
    }

    void
    join()
    {
      _M_thread.join();
    }

    void
    detach()
    {
      _M_thread.detach();
    }

    [[nodiscard]] id
    get_id() const noexcept
    {
      return _M_thread.get_id();
    }

    [[nodiscard]] native_handle_type
    native_handle()
    {
      return _M_thread.native_handle();
    }

    [[nodiscard]] static unsigned
    hardware_concurrency() noexcept
    {
      return thread::hardware_concurrency();
    }

    [[nodiscard]] stop_source
    get_stop_source() noexcept
    {
      return _M_stop_source;
    }

    [[nodiscard]] stop_token
    get_stop_token() const noexcept
    {
      return _M_stop_source.get_token();
    }

    bool request_stop() noexcept
    {
      return _M_stop_source.request_stop();
    }

    friend void swap(jthread& __lhs, jthread& __rhs) noexcept
    {
      __lhs.swap(__rhs);
    }

  private:
    template<typename _Callable, typename... _Args>
      static thread
      _S_create(stop_source& __ssrc, _Callable&& __f, _Args&&... __args)
      {
	if constexpr(is_invocable_v<decay_t<_Callable>, stop_token,
				    decay_t<_Args>...>)
	  return thread{std::forward<_Callable>(__f), __ssrc.get_token(),
			std::forward<_Args>(__args)...};
	else
	  {
	    static_assert(is_invocable_v<decay_t<_Callable>,
					 decay_t<_Args>...>,
			  "std::thread arguments must be invocable after"
			  " conversion to rvalues");
	    return thread{std::forward<_Callable>(__f),
			  std::forward<_Args>(__args)...};
	  }
      }

    stop_source _M_stop_source;
    thread _M_thread;
  };
#endif // __cpp_lib_jthread

  // @} group threads

_GLIBCXX_END_NAMESPACE_VERSION
} // namespace
#endif // C++11
#endif // _GLIBCXX_THREAD