mutex

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// <mutex> -*- C++ -*-

// Copyright (C) 2003-2015 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/mutex
 *  This is a Standard C++ Library header.
 */

#ifndef _GLIBCXX_MUTEX
#define _GLIBCXX_MUTEX 1

#pragma GCC system_header

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

#include <tuple>
#include <chrono>
#include <exception>
#include <type_traits>
#include <functional>
#include <system_error>
#include <bits/functexcept.h>
#include <bits/gthr.h>
#include <bits/move.h> // for std::swap
#include <bits/cxxabi_forced.h>

#ifdef _GLIBCXX_USE_C99_STDINT_TR1

namespace std _GLIBCXX_VISIBILITY(default)
{
_GLIBCXX_BEGIN_NAMESPACE_VERSION

#ifdef _GLIBCXX_HAS_GTHREADS
  // Common base class for std::mutex and std::timed_mutex
  class __mutex_base
  {
  protected:
    typedef __gthread_mutex_t                      __native_type;

#ifdef __GTHREAD_MUTEX_INIT
    __native_type  _M_mutex = __GTHREAD_MUTEX_INIT;

    constexpr __mutex_base() noexcept = default;
#else
    __native_type  _M_mutex;

    __mutex_base() noexcept
    {
      // XXX EAGAIN, ENOMEM, EPERM, EBUSY(may), EINVAL(may)
      __GTHREAD_MUTEX_INIT_FUNCTION(&_M_mutex);
    }

    ~__mutex_base() noexcept { __gthread_mutex_destroy(&_M_mutex); }
#endif

    __mutex_base(const __mutex_base&) = delete;
    __mutex_base& operator=(const __mutex_base&) = delete;
  };

  // Common base class for std::recursive_mutex and std::recursive_timed_mutex
  class __recursive_mutex_base
  {
  protected:
    typedef __gthread_recursive_mutex_t            __native_type;

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

#ifdef __GTHREAD_RECURSIVE_MUTEX_INIT
    __native_type  _M_mutex = __GTHREAD_RECURSIVE_MUTEX_INIT;

    __recursive_mutex_base() = default;
#else
    __native_type  _M_mutex;

    __recursive_mutex_base()
    {
      // XXX EAGAIN, ENOMEM, EPERM, EBUSY(may), EINVAL(may)
      __GTHREAD_RECURSIVE_MUTEX_INIT_FUNCTION(&_M_mutex);
    }

    ~__recursive_mutex_base()
    { __gthread_recursive_mutex_destroy(&_M_mutex); }
#endif
  };

  /**
   * @defgroup mutexes Mutexes
   * @ingroup concurrency
   *
   * Classes for mutex support.
   * @{
   */

  /// The standard mutex type.
  class mutex : private __mutex_base
  {
  public:
    typedef __native_type*                         native_handle_type;

#ifdef __GTHREAD_MUTEX_INIT
    constexpr
#endif
    mutex() noexcept = default;
    ~mutex() = default;

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

    void
    lock()
    {
      int __e = __gthread_mutex_lock(&_M_mutex);

      // EINVAL, EAGAIN, EBUSY, EINVAL, EDEADLK(may)
      if (__e)
   __throw_system_error(__e);
    }

    bool
    try_lock() noexcept
    {
      // XXX EINVAL, EAGAIN, EBUSY
      return !__gthread_mutex_trylock(&_M_mutex);
    }

    void
    unlock()
    {
      // XXX EINVAL, EAGAIN, EPERM
      __gthread_mutex_unlock(&_M_mutex);
    }

    native_handle_type
    native_handle()
    { return &_M_mutex; }
  };

  /// The standard recursive mutex type.
  class recursive_mutex : private __recursive_mutex_base
  {
  public:
    typedef __native_type*                         native_handle_type;

    recursive_mutex() = default;
    ~recursive_mutex() = default;

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

    void
    lock()
    {
      int __e = __gthread_recursive_mutex_lock(&_M_mutex);

      // EINVAL, EAGAIN, EBUSY, EINVAL, EDEADLK(may)
      if (__e)
   __throw_system_error(__e);
    }

    bool
    try_lock() noexcept
    {
      // XXX EINVAL, EAGAIN, EBUSY
      return !__gthread_recursive_mutex_trylock(&_M_mutex);
    }

    void
    unlock()
    {
      // XXX EINVAL, EAGAIN, EBUSY
      __gthread_recursive_mutex_unlock(&_M_mutex);
    }

    native_handle_type
    native_handle()
    { return &_M_mutex; }
  };

#if _GTHREAD_USE_MUTEX_TIMEDLOCK
  template<typename _Derived>
    class __timed_mutex_impl
    {
    protected:
      typedef chrono::high_resolution_clock        __clock_t;

      template<typename _Rep, typename _Period>
   bool
   _M_try_lock_for(const chrono::duration<_Rep, _Period>& __rtime)
   {
     using chrono::steady_clock;
     auto __rt = chrono::duration_cast<steady_clock::duration>(__rtime);
     if (ratio_greater<steady_clock::period, _Period>())
       ++__rt;
     return _M_try_lock_until(steady_clock::now() + __rt);
   }

      template<typename _Duration>
   bool
   _M_try_lock_until(const chrono::time_point<__clock_t,
                                              _Duration>& __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())
     };

     auto __mutex = static_cast<_Derived*>(this)->native_handle();
     return !__gthread_mutex_timedlock(__mutex, &__ts);
   }

      template<typename _Clock, typename _Duration>
   bool
   _M_try_lock_until(const chrono::time_point<_Clock, _Duration>& __atime)
   {
     auto __rtime = __atime - _Clock::now();
     return _M_try_lock_until(__clock_t::now() + __rtime);
   }
    };

  /// The standard timed mutex type.
  class timed_mutex
  : private __mutex_base, public __timed_mutex_impl<timed_mutex>
  {
  public:
    typedef __native_type*                         native_handle_type;

    timed_mutex() = default;
    ~timed_mutex() = default;

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

    void
    lock()
    {
      int __e = __gthread_mutex_lock(&_M_mutex);

      // EINVAL, EAGAIN, EBUSY, EINVAL, EDEADLK(may)
      if (__e)
   __throw_system_error(__e);
    }

    bool
    try_lock() noexcept
    {
      // XXX EINVAL, EAGAIN, EBUSY
      return !__gthread_mutex_trylock(&_M_mutex);
    }

    template <class _Rep, class _Period>
      bool
      try_lock_for(const chrono::duration<_Rep, _Period>& __rtime)
      { return _M_try_lock_for(__rtime); }

    template <class _Clock, class _Duration>
      bool
      try_lock_until(const chrono::time_point<_Clock, _Duration>& __atime)
      { return _M_try_lock_until(__atime); }

    void
    unlock()
    {
      // XXX EINVAL, EAGAIN, EBUSY
      __gthread_mutex_unlock(&_M_mutex);
    }

    native_handle_type
    native_handle()
    { return &_M_mutex; }
  };

  /// The standard recursive timed mutex type.
  class recursive_timed_mutex
  : private __recursive_mutex_base,
    public __timed_mutex_impl<recursive_timed_mutex>
  {
  public:
    typedef __native_type*                         native_handle_type;

    recursive_timed_mutex() = default;
    ~recursive_timed_mutex() = default;

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

    void
    lock()
    {
      int __e = __gthread_recursive_mutex_lock(&_M_mutex);

      // EINVAL, EAGAIN, EBUSY, EINVAL, EDEADLK(may)
      if (__e)
   __throw_system_error(__e);
    }

    bool
    try_lock() noexcept
    {
      // XXX EINVAL, EAGAIN, EBUSY
      return !__gthread_recursive_mutex_trylock(&_M_mutex);
    }

    template <class _Rep, class _Period>
      bool
      try_lock_for(const chrono::duration<_Rep, _Period>& __rtime)
      { return _M_try_lock_for(__rtime); }

    template <class _Clock, class _Duration>
      bool
      try_lock_until(const chrono::time_point<_Clock, _Duration>& __atime)
      { return _M_try_lock_until(__atime); }

    void
    unlock()
    {
      // XXX EINVAL, EAGAIN, EBUSY
      __gthread_recursive_mutex_unlock(&_M_mutex);
    }

    native_handle_type
    native_handle()
    { return &_M_mutex; }
  };
#endif
#endif // _GLIBCXX_HAS_GTHREADS

  /// Do not acquire ownership of the mutex.
  struct defer_lock_t { };

  /// Try to acquire ownership of the mutex without blocking.
  struct try_to_lock_t { };

  /// Assume the calling thread has already obtained mutex ownership
  /// and manage it.
  struct adopt_lock_t { };

  /// Tag used to prevent a scoped lock from acquiring ownership of a mutex.
  constexpr defer_lock_t   defer_lock { };

  /// Tag used to prevent a scoped lock from blocking if a mutex is locked.
  constexpr try_to_lock_t  try_to_lock { };

  /// Tag used to make a scoped lock take ownership of a locked mutex.
  constexpr adopt_lock_t   adopt_lock { };

  /** @brief A movable scoped lock type.
   *
   * A unique_lock controls mutex ownership within a scope. Ownership of the
   * mutex can be delayed until after construction and can be transferred
   * to another unique_lock by move construction or move assignment. If a
   * mutex lock is owned when the destructor runs ownership will be released.
   */
  template<typename _Mutex>
    class lock_guard
    {
    public:
      typedef _Mutex mutex_type;

      explicit lock_guard(mutex_type& __m) : _M_device(__m)
      { _M_device.lock(); }

      lock_guard(mutex_type& __m, adopt_lock_t) : _M_device(__m)
      { } // calling thread owns mutex

      ~lock_guard()
      { _M_device.unlock(); }

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

    private:
      mutex_type&  _M_device;
    };

  /// unique_lock
  template<typename _Mutex>
    class unique_lock
    {
    public:
      typedef _Mutex mutex_type;

      unique_lock() noexcept
      : _M_device(0), _M_owns(false)
      { }

      explicit unique_lock(mutex_type& __m)
      : _M_device(std::__addressof(__m)), _M_owns(false)
      {
   lock();
   _M_owns = true;
      }

      unique_lock(mutex_type& __m, defer_lock_t) noexcept
      : _M_device(std::__addressof(__m)), _M_owns(false)
      { }

      unique_lock(mutex_type& __m, try_to_lock_t)
      : _M_device(std::__addressof(__m)), _M_owns(_M_device->try_lock())
      { }

      unique_lock(mutex_type& __m, adopt_lock_t)
      : _M_device(std::__addressof(__m)), _M_owns(true)
      {
   // XXX calling thread owns mutex
      }

      template<typename _Clock, typename _Duration>
   unique_lock(mutex_type& __m,
               const chrono::time_point<_Clock, _Duration>& __atime)
   : _M_device(std::__addressof(__m)),
     _M_owns(_M_device->try_lock_until(__atime))
   { }

      template<typename _Rep, typename _Period>
   unique_lock(mutex_type& __m,
               const chrono::duration<_Rep, _Period>& __rtime)
   : _M_device(std::__addressof(__m)),
     _M_owns(_M_device->try_lock_for(__rtime))
   { }

      ~unique_lock()
      {
   if (_M_owns)
     unlock();
      }

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

      unique_lock(unique_lock&& __u) noexcept
      : _M_device(__u._M_device), _M_owns(__u._M_owns)
      {
   __u._M_device = 0;
   __u._M_owns = false;
      }

      unique_lock& operator=(unique_lock&& __u) noexcept
      {
   if(_M_owns)
     unlock();

   unique_lock(std::move(__u)).swap(*this);

   __u._M_device = 0;
   __u._M_owns = false;

   return *this;
      }

      void
      lock()
      {
   if (!_M_device)
     __throw_system_error(int(errc::operation_not_permitted));
   else if (_M_owns)
     __throw_system_error(int(errc::resource_deadlock_would_occur));
   else
     {
       _M_device->lock();
       _M_owns = true;
     }
      }

      bool
      try_lock()
      {
   if (!_M_device)
     __throw_system_error(int(errc::operation_not_permitted));
   else if (_M_owns)
     __throw_system_error(int(errc::resource_deadlock_would_occur));
   else
     {
       _M_owns = _M_device->try_lock();
       return _M_owns;
     }
      }

      template<typename _Clock, typename _Duration>
   bool
   try_lock_until(const chrono::time_point<_Clock, _Duration>& __atime)
   {
     if (!_M_device)
       __throw_system_error(int(errc::operation_not_permitted));
     else if (_M_owns)
       __throw_system_error(int(errc::resource_deadlock_would_occur));
     else
       {
         _M_owns = _M_device->try_lock_until(__atime);
         return _M_owns;
       }
   }

      template<typename _Rep, typename _Period>
   bool
   try_lock_for(const chrono::duration<_Rep, _Period>& __rtime)
   {
     if (!_M_device)
       __throw_system_error(int(errc::operation_not_permitted));
     else if (_M_owns)
       __throw_system_error(int(errc::resource_deadlock_would_occur));
     else
       {
         _M_owns = _M_device->try_lock_for(__rtime);
         return _M_owns;
       }
    }

      void
      unlock()
      {
   if (!_M_owns)
     __throw_system_error(int(errc::operation_not_permitted));
   else if (_M_device)
     {
       _M_device->unlock();
       _M_owns = false;
     }
      }

      void
      swap(unique_lock& __u) noexcept
      {
   std::swap(_M_device, __u._M_device);
   std::swap(_M_owns, __u._M_owns);
      }

      mutex_type*
      release() noexcept
      {
   mutex_type* __ret = _M_device;
   _M_device = 0;
   _M_owns = false;
   return __ret;
      }

      bool
      owns_lock() const noexcept
      { return _M_owns; }

      explicit operator bool() const noexcept
      { return owns_lock(); }

      mutex_type*
      mutex() const noexcept
      { return _M_device; }

    private:
      mutex_type*  _M_device;
      bool         _M_owns; // XXX use atomic_bool
    };

  /// Swap overload for unique_lock objects.
  template<typename _Mutex>
    inline void
    swap(unique_lock<_Mutex>& __x, unique_lock<_Mutex>& __y) noexcept
    { __x.swap(__y); }

  template<typename _Lock>
    inline unique_lock<_Lock>
    __try_to_lock(_Lock& __l)
    { return unique_lock<_Lock>{__l, try_to_lock}; }

  template<int _Idx, bool _Continue = true>
    struct __try_lock_impl
    {
      template<typename... _Lock>
   static void
   __do_try_lock(tuple<_Lock&...>& __locks, int& __idx)
   {
          __idx = _Idx;
          auto __lock = std::__try_to_lock(std::get<_Idx>(__locks));
          if (__lock.owns_lock())
            {
         constexpr bool __cont = _Idx + 2 < sizeof...(_Lock);
         using __try_locker = __try_lock_impl<_Idx + 1, __cont>;
         __try_locker::__do_try_lock(__locks, __idx);
              if (__idx == -1)
                __lock.release();
            }
   }
    };

  template<int _Idx>
    struct __try_lock_impl<_Idx, false>
    {
      template<typename... _Lock>
   static void
   __do_try_lock(tuple<_Lock&...>& __locks, int& __idx)
   {
          __idx = _Idx;
          auto __lock = std::__try_to_lock(std::get<_Idx>(__locks));
          if (__lock.owns_lock())
            {
              __idx = -1;
              __lock.release();
            }
   }
    };

  /** @brief Generic try_lock.
   *  @param __l1 Meets Mutex requirements (try_lock() may throw).
   *  @param __l2 Meets Mutex requirements (try_lock() may throw).
   *  @param __l3 Meets Mutex requirements (try_lock() may throw).
   *  @return Returns -1 if all try_lock() calls return true. Otherwise returns
   *          a 0-based index corresponding to the argument that returned false.
   *  @post Either all arguments are locked, or none will be.
   *
   *  Sequentially calls try_lock() on each argument.
   */
  template<typename _Lock1, typename _Lock2, typename... _Lock3>
    int
    try_lock(_Lock1& __l1, _Lock2& __l2, _Lock3&... __l3)
    {
      int __idx;
      auto __locks = std::tie(__l1, __l2, __l3...);
      __try_lock_impl<0>::__do_try_lock(__locks, __idx);
      return __idx;
    }

  /** @brief Generic lock.
   *  @param __l1 Meets Mutex requirements (try_lock() may throw).
   *  @param __l2 Meets Mutex requirements (try_lock() may throw).
   *  @param __l3 Meets Mutex requirements (try_lock() may throw).
   *  @throw An exception thrown by an argument's lock() or try_lock() member.
   *  @post All arguments are locked.
   *
   *  All arguments are locked via a sequence of calls to lock(), try_lock()
   *  and unlock().  If the call exits via an exception any locks that were
   *  obtained will be released.
   */
  template<typename _L1, typename _L2, typename... _L3>
    void
    lock(_L1& __l1, _L2& __l2, _L3&... __l3)
    {
      while (true)
        {
          using __try_locker = __try_lock_impl<0, sizeof...(_L3) != 0>;
          unique_lock<_L1> __first(__l1);
          int __idx;
          auto __locks = std::tie(__l2, __l3...);
          __try_locker::__do_try_lock(__locks, __idx);
          if (__idx == -1)
            {
              __first.release();
              return;
            }
        }
    }

#ifdef _GLIBCXX_HAS_GTHREADS
  /// once_flag
  struct once_flag
  {
  private:
    typedef __gthread_once_t __native_type;
    __native_type  _M_once = __GTHREAD_ONCE_INIT;

  public:
    /// Constructor
    constexpr once_flag() noexcept = default;

    /// Deleted copy constructor
    once_flag(const once_flag&) = delete;
    /// Deleted assignment operator
    once_flag& operator=(const once_flag&) = delete;

    template<typename _Callable, typename... _Args>
      friend void
      call_once(once_flag& __once, _Callable&& __f, _Args&&... __args);
  };

#ifdef _GLIBCXX_HAVE_TLS
  extern __thread void* __once_callable;
  extern __thread void (*__once_call)();

  template<typename _Callable>
    inline void
    __once_call_impl()
    {
      (*(_Callable*)__once_callable)();
    }
#else
  extern function<void()> __once_functor;

  extern void
  __set_once_functor_lock_ptr(unique_lock<mutex>*);

  extern mutex&
  __get_once_mutex();
#endif

  extern "C" void __once_proxy(void);

  /// call_once
  template<typename _Callable, typename... _Args>
    void
    call_once(once_flag& __once, _Callable&& __f, _Args&&... __args)
    {
#ifdef _GLIBCXX_HAVE_TLS
      auto __bound_functor = std::__bind_simple(std::forward<_Callable>(__f),
          std::forward<_Args>(__args)...);
      __once_callable = std::__addressof(__bound_functor);
      __once_call = &__once_call_impl<decltype(__bound_functor)>;
#else
      unique_lock<mutex> __functor_lock(__get_once_mutex());
      auto __callable = std::__bind_simple(std::forward<_Callable>(__f),
          std::forward<_Args>(__args)...);
      __once_functor = [&]() { __callable(); };
      __set_once_functor_lock_ptr(&__functor_lock);
#endif

      int __e = __gthread_once(&__once._M_once, &__once_proxy);

#ifndef _GLIBCXX_HAVE_TLS
      if (__functor_lock)
        __set_once_functor_lock_ptr(0);
#endif

      if (__e)
   __throw_system_error(__e);
    }
#endif // _GLIBCXX_HAS_GTHREADS

  // @} group mutexes
_GLIBCXX_END_NAMESPACE_VERSION
} // namespace
#endif // _GLIBCXX_USE_C99_STDINT_TR1

#endif // C++11

#endif // _GLIBCXX_MUTEX