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Edit File: condition_variable

// <condition_variable> -*- C++ -*-

// Copyright (C) 2008-2019 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/condition_variable
 *  This is a Standard C++ Library header.
 */

#ifndef _GLIBCXX_CONDITION_VARIABLE
#define _GLIBCXX_CONDITION_VARIABLE 1

#pragma GCC system_header

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

#include <chrono>
#include <bits/std_mutex.h>
#include <bits/unique_lock.h>
#include <ext/concurrence.h>
#include <bits/alloc_traits.h>
#include <bits/allocator.h>
#include <bits/unique_ptr.h>
#include <bits/shared_ptr.h>
#include <bits/cxxabi_forced.h>

#if defined(_GLIBCXX_HAS_GTHREADS)

namespace std _GLIBCXX_VISIBILITY(default)
{
_GLIBCXX_BEGIN_NAMESPACE_VERSION

/**
   * @defgroup condition_variables Condition Variables
   * @ingroup concurrency
   *
   * Classes for condition_variable support.
   * @{
   */

/// cv_status
  enum class cv_status { no_timeout, timeout };

/// condition_variable
  class condition_variable
  {
    typedef chrono::system_clock	__clock_t;
    typedef chrono::steady_clock	__steady_clock_t;
    typedef __gthread_cond_t		__native_type;

#ifdef __GTHREAD_COND_INIT
    __native_type			_M_cond = __GTHREAD_COND_INIT;
#else
    __native_type			_M_cond;
#endif

public:
    typedef __native_type* 		native_handle_type;

condition_variable() noexcept;
    ~condition_variable() noexcept;

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

void
    notify_one() noexcept;

void
    notify_all() noexcept;

void
    wait(unique_lock<mutex>& __lock) noexcept;

template<typename _Predicate>
      void
      wait(unique_lock<mutex>& __lock, _Predicate __p)
      {
	while (!__p())
	  wait(__lock);
      }

template<typename _Duration>
      cv_status
      wait_until(unique_lock<mutex>& __lock,
		 const chrono::time_point<__clock_t, _Duration>& __atime)
      { return __wait_until_impl(__lock, __atime); }

template<typename _Clock, typename _Duration>
      cv_status
      wait_until(unique_lock<mutex>& __lock,
		 const chrono::time_point<_Clock, _Duration>& __atime)
      {
	// DR 887 - Sync unknown clock to known clock.
	const typename _Clock::time_point __c_entry = _Clock::now();
	const __clock_t::time_point __s_entry = __clock_t::now();
	const auto __delta = __atime - __c_entry;
	const auto __s_atime = __s_entry + __delta;

if (__wait_until_impl(__lock, __s_atime) == cv_status::no_timeout)
	  return cv_status::no_timeout;
	// We got a timeout when measured against __clock_t but
	// we need to check against the caller-supplied clock
	// to tell whether we should return a timeout.
	if (_Clock::now() < __atime)
	  return cv_status::no_timeout;
	return cv_status::timeout;
      }

template<typename _Clock, typename _Duration, typename _Predicate>
      bool
      wait_until(unique_lock<mutex>& __lock,
		 const chrono::time_point<_Clock, _Duration>& __atime,
		 _Predicate __p)
      {
	while (!__p())
	  if (wait_until(__lock, __atime) == cv_status::timeout)
	    return __p();
	return true;
      }

template<typename _Rep, typename _Period>
      cv_status
      wait_for(unique_lock<mutex>& __lock,
	       const chrono::duration<_Rep, _Period>& __rtime)
      {
	using __dur = typename __steady_clock_t::duration;
	auto __reltime = chrono::duration_cast<__dur>(__rtime);
	if (__reltime < __rtime)
	  ++__reltime;
	return wait_until(__lock, __steady_clock_t::now() + __reltime);
      }

template<typename _Rep, typename _Period, typename _Predicate>
      bool
      wait_for(unique_lock<mutex>& __lock,
	       const chrono::duration<_Rep, _Period>& __rtime,
	       _Predicate __p)
      {
	using __dur = typename __steady_clock_t::duration;
	auto __reltime = chrono::duration_cast<__dur>(__rtime);
	if (__reltime < __rtime)
	  ++__reltime;
	return wait_until(__lock, __steady_clock_t::now() + __reltime,
			  std::move(__p));
      }

native_handle_type
    native_handle()
    { return &_M_cond; }

private:
    template<typename _Dur>
      cv_status
      __wait_until_impl(unique_lock<mutex>& __lock,
			const chrono::time_point<__clock_t, _Dur>& __atime)
      {
	auto __s = chrono::time_point_cast<chrono::seconds>(__atime);
	auto __ns = chrono::duration_cast<chrono::nanoseconds>(__atime - __s);

__gthread_time_t __ts =
	  {
	    static_cast<std::time_t>(__s.time_since_epoch().count()),
	    static_cast<long>(__ns.count())
	  };

__gthread_cond_timedwait(&_M_cond, __lock.mutex()->native_handle(),
				 &__ts);

return (__clock_t::now() < __atime
		? cv_status::no_timeout : cv_status::timeout);
      }
  };

void
  notify_all_at_thread_exit(condition_variable&, unique_lock<mutex>);

struct __at_thread_exit_elt
  {
    __at_thread_exit_elt* _M_next;
    void (*_M_cb)(void*);
  };

inline namespace _V2 {

/// condition_variable_any
  // Like above, but mutex is not required to have try_lock.
  class condition_variable_any
  {
    typedef chrono::system_clock	__clock_t;
    condition_variable			_M_cond;
    shared_ptr<mutex>			_M_mutex;

// scoped unlock - unlocks in ctor, re-locks in dtor
    template<typename _Lock>
      struct _Unlock
      {
	explicit _Unlock(_Lock& __lk) : _M_lock(__lk) { __lk.unlock(); }

~_Unlock() noexcept(false)
	{
	  if (uncaught_exception())
	    {
	      __try
	      { _M_lock.lock(); }
	      __catch(const __cxxabiv1::__forced_unwind&)
	      { __throw_exception_again; }
	      __catch(...)
	      { }
	    }
	  else
	    _M_lock.lock();
	}

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

_Lock& _M_lock;
      };

public:
    condition_variable_any() : _M_mutex(std::make_shared<mutex>()) { }
    ~condition_variable_any() = default;

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

void
    notify_one() noexcept
    {
      lock_guard<mutex> __lock(*_M_mutex);
      _M_cond.notify_one();
    }

void
    notify_all() noexcept
    {
      lock_guard<mutex> __lock(*_M_mutex);
      _M_cond.notify_all();
    }

template<typename _Lock>
      void
      wait(_Lock& __lock)
      {
	shared_ptr<mutex> __mutex = _M_mutex;
	unique_lock<mutex> __my_lock(*__mutex);
	_Unlock<_Lock> __unlock(__lock);
	// *__mutex must be unlocked before re-locking __lock so move
	// ownership of *__mutex lock to an object with shorter lifetime.
	unique_lock<mutex> __my_lock2(std::move(__my_lock));
	_M_cond.wait(__my_lock2);
      }

template<typename _Lock, typename _Predicate>
      void
      wait(_Lock& __lock, _Predicate __p)
      {
	while (!__p())
	  wait(__lock);
      }

template<typename _Lock, typename _Clock, typename _Duration>
      cv_status
      wait_until(_Lock& __lock,
		 const chrono::time_point<_Clock, _Duration>& __atime)
      {
	shared_ptr<mutex> __mutex = _M_mutex;
	unique_lock<mutex> __my_lock(*__mutex);
	_Unlock<_Lock> __unlock(__lock);
	// *__mutex must be unlocked before re-locking __lock so move
	// ownership of *__mutex lock to an object with shorter lifetime.
	unique_lock<mutex> __my_lock2(std::move(__my_lock));
	return _M_cond.wait_until(__my_lock2, __atime);
      }

template<typename _Lock, typename _Clock,
	     typename _Duration, typename _Predicate>
      bool
      wait_until(_Lock& __lock,
		 const chrono::time_point<_Clock, _Duration>& __atime,
		 _Predicate __p)
      {
	while (!__p())
	  if (wait_until(__lock, __atime) == cv_status::timeout)
	    return __p();
	return true;
      }

template<typename _Lock, typename _Rep, typename _Period>
      cv_status
      wait_for(_Lock& __lock, const chrono::duration<_Rep, _Period>& __rtime)
      { return wait_until(__lock, __clock_t::now() + __rtime); }

template<typename _Lock, typename _Rep,
	     typename _Period, typename _Predicate>
      bool
      wait_for(_Lock& __lock,
	       const chrono::duration<_Rep, _Period>& __rtime, _Predicate __p)
      { return wait_until(__lock, __clock_t::now() + __rtime, std::move(__p)); }
  };

} // end inline namespace

/// @} group condition_variables
_GLIBCXX_END_NAMESPACE_VERSION
} // namespace

#endif // _GLIBCXX_HAS_GTHREADS
#endif // C++11
#endif // _GLIBCXX_CONDITION_VARIABLE