374 lines
9.0 KiB
C++
374 lines
9.0 KiB
C++
// std::mutex implementation -*- C++ -*-
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// Copyright (C) 2003-2016 Free Software Foundation, Inc.
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//
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// This file is part of the GNU ISO C++ Library. This library is free
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// software; you can redistribute it and/or modify it under the
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// terms of the GNU General Public License as published by the
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// Free Software Foundation; either version 3, or (at your option)
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// any later version.
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// This library is distributed in the hope that it will be useful,
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// but WITHOUT ANY WARRANTY; without even the implied warranty of
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// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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// GNU General Public License for more details.
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// Under Section 7 of GPL version 3, you are granted additional
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// permissions described in the GCC Runtime Library Exception, version
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// 3.1, as published by the Free Software Foundation.
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// You should have received a copy of the GNU General Public License and
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// a copy of the GCC Runtime Library Exception along with this program;
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// see the files COPYING3 and COPYING.RUNTIME respectively. If not, see
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// <http://www.gnu.org/licenses/>.
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/** @file bits/std_mutex.h
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* This is an internal header file, included by other library headers.
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* Do not attempt to use it directly. @headername{mutex}
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*/
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#ifndef _GLIBCXX_MUTEX_H
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#define _GLIBCXX_MUTEX_H 1
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#pragma GCC system_header
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#if __cplusplus < 201103L
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# include <bits/c++0x_warning.h>
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#else
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#include <system_error>
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#include <bits/functexcept.h>
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#include <bits/gthr.h>
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#include <bits/move.h> // for std::swap
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#ifdef _GLIBCXX_USE_C99_STDINT_TR1
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namespace std _GLIBCXX_VISIBILITY(default)
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{
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_GLIBCXX_BEGIN_NAMESPACE_VERSION
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/**
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* @defgroup mutexes Mutexes
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* @ingroup concurrency
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*
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* Classes for mutex support.
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* @{
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*/
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#ifdef _GLIBCXX_HAS_GTHREADS
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// Common base class for std::mutex and std::timed_mutex
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class __mutex_base
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{
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protected:
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typedef __gthread_mutex_t __native_type;
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#ifdef __GTHREAD_MUTEX_INIT
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__native_type _M_mutex = __GTHREAD_MUTEX_INIT;
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constexpr __mutex_base() noexcept = default;
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#else
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__native_type _M_mutex;
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__mutex_base() noexcept
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{
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// XXX EAGAIN, ENOMEM, EPERM, EBUSY(may), EINVAL(may)
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__GTHREAD_MUTEX_INIT_FUNCTION(&_M_mutex);
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}
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~__mutex_base() noexcept { __gthread_mutex_destroy(&_M_mutex); }
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#endif
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__mutex_base(const __mutex_base&) = delete;
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__mutex_base& operator=(const __mutex_base&) = delete;
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};
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/// The standard mutex type.
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class mutex : private __mutex_base
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{
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public:
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typedef __native_type* native_handle_type;
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#ifdef __GTHREAD_MUTEX_INIT
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constexpr
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#endif
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mutex() noexcept = default;
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~mutex() = default;
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mutex(const mutex&) = delete;
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mutex& operator=(const mutex&) = delete;
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void
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lock()
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{
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int __e = __gthread_mutex_lock(&_M_mutex);
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// EINVAL, EAGAIN, EBUSY, EINVAL, EDEADLK(may)
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if (__e)
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__throw_system_error(__e);
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}
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bool
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try_lock() noexcept
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{
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// XXX EINVAL, EAGAIN, EBUSY
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return !__gthread_mutex_trylock(&_M_mutex);
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}
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void
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unlock()
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{
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// XXX EINVAL, EAGAIN, EPERM
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__gthread_mutex_unlock(&_M_mutex);
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}
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native_handle_type
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native_handle()
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{ return &_M_mutex; }
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};
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#endif // _GLIBCXX_HAS_GTHREADS
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/// Do not acquire ownership of the mutex.
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struct defer_lock_t { explicit defer_lock_t() = default; };
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/// Try to acquire ownership of the mutex without blocking.
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struct try_to_lock_t { explicit try_to_lock_t() = default; };
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/// Assume the calling thread has already obtained mutex ownership
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/// and manage it.
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struct adopt_lock_t { explicit adopt_lock_t() = default; };
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/// Tag used to prevent a scoped lock from acquiring ownership of a mutex.
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constexpr defer_lock_t defer_lock { };
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/// Tag used to prevent a scoped lock from blocking if a mutex is locked.
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constexpr try_to_lock_t try_to_lock { };
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/// Tag used to make a scoped lock take ownership of a locked mutex.
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constexpr adopt_lock_t adopt_lock { };
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/** @brief A simple scoped lock type.
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*
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* A lock_guard controls mutex ownership within a scope, releasing
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* ownership in the destructor.
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*/
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template<typename _Mutex>
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class lock_guard
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{
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public:
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typedef _Mutex mutex_type;
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explicit lock_guard(mutex_type& __m) : _M_device(__m)
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{ _M_device.lock(); }
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lock_guard(mutex_type& __m, adopt_lock_t) : _M_device(__m)
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{ } // calling thread owns mutex
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~lock_guard()
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{ _M_device.unlock(); }
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lock_guard(const lock_guard&) = delete;
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lock_guard& operator=(const lock_guard&) = delete;
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private:
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mutex_type& _M_device;
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};
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/** @brief A movable scoped lock type.
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*
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* A unique_lock controls mutex ownership within a scope. Ownership of the
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* mutex can be delayed until after construction and can be transferred
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* to another unique_lock by move construction or move assignment. If a
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* mutex lock is owned when the destructor runs ownership will be released.
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*/
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template<typename _Mutex>
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class unique_lock
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{
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public:
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typedef _Mutex mutex_type;
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unique_lock() noexcept
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: _M_device(0), _M_owns(false)
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{ }
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explicit unique_lock(mutex_type& __m)
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: _M_device(std::__addressof(__m)), _M_owns(false)
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{
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lock();
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_M_owns = true;
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}
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unique_lock(mutex_type& __m, defer_lock_t) noexcept
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: _M_device(std::__addressof(__m)), _M_owns(false)
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{ }
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unique_lock(mutex_type& __m, try_to_lock_t)
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: _M_device(std::__addressof(__m)), _M_owns(_M_device->try_lock())
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{ }
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unique_lock(mutex_type& __m, adopt_lock_t)
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: _M_device(std::__addressof(__m)), _M_owns(true)
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{
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// XXX calling thread owns mutex
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}
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template<typename _Clock, typename _Duration>
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unique_lock(mutex_type& __m,
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const chrono::time_point<_Clock, _Duration>& __atime)
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: _M_device(std::__addressof(__m)),
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_M_owns(_M_device->try_lock_until(__atime))
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{ }
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template<typename _Rep, typename _Period>
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unique_lock(mutex_type& __m,
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const chrono::duration<_Rep, _Period>& __rtime)
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: _M_device(std::__addressof(__m)),
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_M_owns(_M_device->try_lock_for(__rtime))
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{ }
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~unique_lock()
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{
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if (_M_owns)
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unlock();
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}
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unique_lock(const unique_lock&) = delete;
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unique_lock& operator=(const unique_lock&) = delete;
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unique_lock(unique_lock&& __u) noexcept
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: _M_device(__u._M_device), _M_owns(__u._M_owns)
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{
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__u._M_device = 0;
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__u._M_owns = false;
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}
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unique_lock& operator=(unique_lock&& __u) noexcept
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{
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if(_M_owns)
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unlock();
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unique_lock(std::move(__u)).swap(*this);
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__u._M_device = 0;
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__u._M_owns = false;
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return *this;
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}
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void
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lock()
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{
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if (!_M_device)
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__throw_system_error(int(errc::operation_not_permitted));
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else if (_M_owns)
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__throw_system_error(int(errc::resource_deadlock_would_occur));
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else
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{
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_M_device->lock();
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_M_owns = true;
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}
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}
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bool
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try_lock()
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{
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if (!_M_device)
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__throw_system_error(int(errc::operation_not_permitted));
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else if (_M_owns)
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__throw_system_error(int(errc::resource_deadlock_would_occur));
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else
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{
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_M_owns = _M_device->try_lock();
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return _M_owns;
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}
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}
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template<typename _Clock, typename _Duration>
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bool
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try_lock_until(const chrono::time_point<_Clock, _Duration>& __atime)
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{
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if (!_M_device)
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__throw_system_error(int(errc::operation_not_permitted));
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else if (_M_owns)
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__throw_system_error(int(errc::resource_deadlock_would_occur));
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else
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{
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_M_owns = _M_device->try_lock_until(__atime);
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return _M_owns;
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}
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}
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template<typename _Rep, typename _Period>
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bool
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try_lock_for(const chrono::duration<_Rep, _Period>& __rtime)
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{
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if (!_M_device)
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__throw_system_error(int(errc::operation_not_permitted));
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else if (_M_owns)
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__throw_system_error(int(errc::resource_deadlock_would_occur));
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else
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{
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_M_owns = _M_device->try_lock_for(__rtime);
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return _M_owns;
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}
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}
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void
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unlock()
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{
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if (!_M_owns)
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__throw_system_error(int(errc::operation_not_permitted));
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else if (_M_device)
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{
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_M_device->unlock();
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_M_owns = false;
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}
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}
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void
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swap(unique_lock& __u) noexcept
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{
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std::swap(_M_device, __u._M_device);
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std::swap(_M_owns, __u._M_owns);
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}
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mutex_type*
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release() noexcept
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{
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mutex_type* __ret = _M_device;
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_M_device = 0;
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_M_owns = false;
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return __ret;
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}
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bool
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owns_lock() const noexcept
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{ return _M_owns; }
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explicit operator bool() const noexcept
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{ return owns_lock(); }
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mutex_type*
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mutex() const noexcept
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{ return _M_device; }
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private:
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mutex_type* _M_device;
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bool _M_owns; // XXX use atomic_bool
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};
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/// Swap overload for unique_lock objects.
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template<typename _Mutex>
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inline void
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swap(unique_lock<_Mutex>& __x, unique_lock<_Mutex>& __y) noexcept
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{ __x.swap(__y); }
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// @} group mutexes
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_GLIBCXX_END_NAMESPACE_VERSION
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} // namespace
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#endif // _GLIBCXX_USE_C99_STDINT_TR1
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#endif // C++11
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#endif // _GLIBCXX_MUTEX_H
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