condition_variable

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// <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