std_mutex.h
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// std::mutex implementation -*- C++ -*-
// Copyright (C) 2003-2024 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 bits/std_mutex.h
* This is an internal header file, included by other library headers.
* Do not attempt to use it directly. @headername{mutex}
*/
#ifndef _GLIBCXX_MUTEX_H
#define _GLIBCXX_MUTEX_H 1
#pragma GCC system_header
#if __cplusplus < 201103L
# include <bits/c++0x_warning.h>
#else
#include <errno.h> // EBUSY
#include <bits/functexcept.h>
#include <bits/gthr.h>
namespace std _GLIBCXX_VISIBILITY(default)
{
_GLIBCXX_BEGIN_NAMESPACE_VERSION
/**
* @defgroup mutexes Mutexes
* @ingroup concurrency
*
* Classes for mutex support.
* @{
*/
#ifdef _GLIBCXX_HAS_GTHREADS
/// @cond undocumented
// 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;
};
/// @endcond
/** The standard mutex type.
*
* A simple, non-recursive, non-timed mutex.
*
* Do not call `lock()` and `unlock()` directly, use a scoped lock type
* such as `std::unique_lock`, `std::lock_guard`, or (since C++17)
* `std::scoped_lock`.
*
* @headerfile mutex
* @since C++11
*/
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);
}
_GLIBCXX_NODISCARD
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() noexcept
{ return &_M_mutex; }
};
/// @cond undocumented
// Implementation details for std::condition_variable
class __condvar
{
using timespec = __gthread_time_t;
public:
__condvar() noexcept
{
#ifndef __GTHREAD_COND_INIT
__GTHREAD_COND_INIT_FUNCTION(&_M_cond);
#endif
}
~__condvar()
{
int __e __attribute__((__unused__)) = __gthread_cond_destroy(&_M_cond);
__glibcxx_assert(__e != EBUSY); // threads are still blocked
}
__condvar(const __condvar&) = delete;
__condvar& operator=(const __condvar&) = delete;
__gthread_cond_t* native_handle() noexcept { return &_M_cond; }
// Expects: Calling thread has locked __m.
void
wait(mutex& __m)
{
int __e __attribute__((__unused__))
= __gthread_cond_wait(&_M_cond, __m.native_handle());
__glibcxx_assert(__e == 0);
}
void
wait_until(mutex& __m, timespec& __abs_time)
{
__gthread_cond_timedwait(&_M_cond, __m.native_handle(), &__abs_time);
}
#ifdef _GLIBCXX_USE_PTHREAD_COND_CLOCKWAIT
void
wait_until(mutex& __m, clockid_t __clock, timespec& __abs_time)
{
pthread_cond_clockwait(&_M_cond, __m.native_handle(), __clock,
&__abs_time);
}
#endif
void
notify_one() noexcept
{
int __e __attribute__((__unused__)) = __gthread_cond_signal(&_M_cond);
__glibcxx_assert(__e == 0);
}
void
notify_all() noexcept
{
int __e __attribute__((__unused__)) = __gthread_cond_broadcast(&_M_cond);
__glibcxx_assert(__e == 0);
}
protected:
#ifdef __GTHREAD_COND_INIT
__gthread_cond_t _M_cond = __GTHREAD_COND_INIT;
#else
__gthread_cond_t _M_cond;
#endif
};
/// @endcond
#endif // _GLIBCXX_HAS_GTHREADS
/// Do not acquire ownership of the mutex.
struct defer_lock_t { explicit defer_lock_t() = default; };
/// Try to acquire ownership of the mutex without blocking.
struct try_to_lock_t { explicit try_to_lock_t() = default; };
/// Assume the calling thread has already obtained mutex ownership
/// and manage it.
struct adopt_lock_t { explicit adopt_lock_t() = default; };
/// Tag used to prevent a scoped lock from acquiring ownership of a mutex.
_GLIBCXX17_INLINE constexpr defer_lock_t defer_lock { };
/// Tag used to prevent a scoped lock from blocking if a mutex is locked.
_GLIBCXX17_INLINE constexpr try_to_lock_t try_to_lock { };
/// Tag used to make a scoped lock take ownership of a locked mutex.
_GLIBCXX17_INLINE constexpr adopt_lock_t adopt_lock { };
/** @brief A simple scoped lock type.
*
* A lock_guard controls mutex ownership within a scope, releasing
* ownership in the destructor.
*
* @headerfile mutex
* @since C++11
*/
template<typename _Mutex>
class lock_guard
{
public:
typedef _Mutex mutex_type;
[[__nodiscard__]]
explicit lock_guard(mutex_type& __m) : _M_device(__m)
{ _M_device.lock(); }
[[__nodiscard__]]
lock_guard(mutex_type& __m, adopt_lock_t) noexcept : _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;
};
/// @} group mutexes
_GLIBCXX_END_NAMESPACE_VERSION
} // namespace
#endif // C++11
#endif // _GLIBCXX_MUTEX_H
functexcept.h
c++0x_warning.h
std::try_to_lock
constexpr try_to_lock_t try_to_lock
Tag used to prevent a scoped lock from blocking if a mutex is locked.
Definition std_mutex.h:229
std::adopt_lock
constexpr adopt_lock_t adopt_lock
Tag used to make a scoped lock take ownership of a locked mutex.
Definition std_mutex.h:232
std::defer_lock
constexpr defer_lock_t defer_lock
Tag used to prevent a scoped lock from acquiring ownership of a mutex.
Definition std_mutex.h:226
std
ISO C++ entities toplevel namespace is std.
std::defer_lock_t
Do not acquire ownership of the mutex.
Definition std_mutex.h:216
std::try_to_lock_t
Try to acquire ownership of the mutex without blocking.
Definition std_mutex.h:219
std::adopt_lock_t
Assume the calling thread has already obtained mutex ownership and manage it.
Definition std_mutex.h:223