mutex

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

// Copyright (C) 2003, 2004, 2005, 2006, 2007, 2008, 2009, 2010, 2011, 2013
// 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

#ifndef __GXX_EXPERIMENTAL_CXX0X__
# 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

#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::timed_recursive_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()
    { _S_destroy(&_M_mutex); }

  private:
    // FIXME: gthreads doesn't define __gthread_recursive_mutex_destroy
    // so we need to obtain a __gthread_mutex_t to destroy

    // matches when there's only one mutex type
    template<typename _Rm>
      static
      typename enable_if<is_same<_Rm, __gthread_mutex_t>::value, void>::type
      _S_destroy(_Rm* __mx)
      { __gthread_mutex_destroy(__mx); }

    // matches a recursive mutex with a member 'actual'
    template<typename _Rm>
      static typename enable_if<(bool)sizeof(&_Rm::actual), void>::type
      _S_destroy(_Rm* __mx)
      { __gthread_mutex_destroy(&__mx->actual); }

    // matches a gthr-win32.h recursive mutex
    template<typename _Rm>
      static typename enable_if<(bool)sizeof(&_Rm::sema), void>::type
      _S_destroy(_Rm* __mx)
      {
        __gthread_mutex_t __tmp;
        _S_destroy_win32(&__tmp, __mx);
      }

    template<typename _Mx, typename _Rm>
      static void
      _S_destroy_win32(_Mx* __mx, _Rm const* __rmx)
      {
        __mx->counter = __rmx->counter;
        __mx->sema = __rmx->sema;
        __gthread_mutex_destroy(__mx);
      }
#endif
  };

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

  /// mutex
  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; }
  };

  /// recursive_mutex
  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
  /// timed_mutex
  class timed_mutex : private __mutex_base
  {
#ifdef _GLIBCXX_USE_CLOCK_MONOTONIC
    typedef chrono::steady_clock        __clock_t;
#else
    typedef chrono::high_resolution_clock   __clock_t;
#endif

  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 __try_lock_for_impl(__rtime); }

    template <class _Clock, class _Duration>
      bool
      try_lock_until(const chrono::time_point<_Clock, _Duration>& __atime)
      {
    chrono::time_point<_Clock, chrono::seconds> __s =
      chrono::time_point_cast<chrono::seconds>(__atime);

    chrono::nanoseconds __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())
    };

    return !__gthread_mutex_timedlock(&_M_mutex, &__ts);
      }

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

    native_handle_type
    native_handle()
    { return &_M_mutex; }

  private:
    template<typename _Rep, typename _Period>
      typename enable_if<
    ratio_less_equal<__clock_t::period, _Period>::value, bool>::type
      __try_lock_for_impl(const chrono::duration<_Rep, _Period>& __rtime)
      {
    __clock_t::time_point __atime = __clock_t::now()
      + chrono::duration_cast<__clock_t::duration>(__rtime);

    return try_lock_until(__atime);
      }

    template <typename _Rep, typename _Period>
      typename enable_if<
    !ratio_less_equal<__clock_t::period, _Period>::value, bool>::type
      __try_lock_for_impl(const chrono::duration<_Rep, _Period>& __rtime)
      {
    __clock_t::time_point __atime = __clock_t::now()
      + ++chrono::duration_cast<__clock_t::duration>(__rtime);

    return try_lock_until(__atime);
      }
  };

  /// recursive_timed_mutex
  class recursive_timed_mutex : private __recursive_mutex_base
  {
#ifdef _GLIBCXX_USE_CLOCK_MONOTONIC
    typedef chrono::steady_clock        __clock_t;
#else
    typedef chrono::high_resolution_clock   __clock_t;
#endif

  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 __try_lock_for_impl(__rtime); }

    template <class _Clock, class _Duration>
      bool
      try_lock_until(const chrono::time_point<_Clock, _Duration>& __atime)
      {
    chrono::time_point<_Clock, chrono::seconds>  __s =
      chrono::time_point_cast<chrono::seconds>(__atime);

    chrono::nanoseconds __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())
    };

    return !__gthread_recursive_mutex_timedlock(&_M_mutex, &__ts);
      }

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

    native_handle_type
    native_handle()
    { return &_M_mutex; }

  private:
    template<typename _Rep, typename _Period>
      typename enable_if<
    ratio_less_equal<__clock_t::period, _Period>::value, bool>::type
      __try_lock_for_impl(const chrono::duration<_Rep, _Period>& __rtime)
      {
    __clock_t::time_point __atime = __clock_t::now()
      + chrono::duration_cast<__clock_t::duration>(__rtime);

    return try_lock_until(__atime);
      }

    template <typename _Rep, typename _Period>
      typename enable_if<
    !ratio_less_equal<__clock_t::period, _Period>::value, bool>::type
      __try_lock_for_impl(const chrono::duration<_Rep, _Period>& __rtime)
      {
    __clock_t::time_point __atime = __clock_t::now()
      + ++chrono::duration_cast<__clock_t::duration>(__rtime);

    return try_lock_until(__atime);
      }
  };
#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 { };

  constexpr defer_lock_t    defer_lock { };
  constexpr try_to_lock_t   try_to_lock { };
  constexpr adopt_lock_t    adopt_lock { };

  /// @brief  Scoped lock idiom.
  // Acquire the mutex here with a constructor call, then release with
  // the destructor call in accordance with RAII style.
  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(&__m), _M_owns(false)
      {
    lock();
    _M_owns = true;
      }

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

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

      unique_lock(mutex_type& __m, adopt_lock_t)
      : _M_device(&__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(&__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(&__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
    };

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

  template<int _Idx>
    struct __unlock_impl
    {
      template<typename... _Lock>
    static void
    __do_unlock(tuple<_Lock&...>& __locks)
    {
      std::get<_Idx>(__locks).unlock();
      __unlock_impl<_Idx - 1>::__do_unlock(__locks);
    }
    };

  template<>
    struct __unlock_impl<-1>
    {
      template<typename... _Lock>
    static void
    __do_unlock(tuple<_Lock&...>&)
    { }
    };

  template<typename _Lock>
    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 = __try_to_lock(std::get<_Idx>(__locks));
          if (__lock.owns_lock())
            {
              __try_lock_impl<_Idx + 1, _Idx + 2 < sizeof...(_Lock)>::
                __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 = __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
      { __try_lock_impl<0>::__do_try_lock(__locks, __idx); }
      __catch(...)
      { }
      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)
        {
          unique_lock<_L1> __first(__l1);
          int __idx;
          auto __locks = std::tie(__l2, __l3...);
          __try_lock_impl<0, sizeof...(_L3)>::__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 = &__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 // __GXX_EXPERIMENTAL_CXX0X__

#endif // _GLIBCXX_MUTEX