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// Support for concurrent programing -*- C++ -*-
// Copyright (C) 2003, 2004, 2005, 2006
// 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 2, 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.
// You should have received a copy of the GNU General Public License along
// with this library; see the file COPYING. If not, write to the Free
// Software Foundation, 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301,
// USA.
// As a special exception, you may use this file as part of a free software
// library without restriction. Specifically, if other files instantiate
// templates or use macros or inline functions from this file, or you compile
// this file and link it with other files to produce an executable, this
// file does not by itself cause the resulting executable to be covered by
// the GNU General Public License. This exception does not however
// invalidate any other reasons why the executable file might be covered by
// the GNU General Public License.
/** @file concurrence.h
* This is an internal header file, included by other library headers.
* You should not attempt to use it directly.
*/
#ifndef _CONCURRENCE_H
#define _CONCURRENCE_H 1
#include <cstdlib>
#include <exception>
#include <bits/gthr.h>
#include <bits/functexcept.h>
_GLIBCXX_BEGIN_NAMESPACE(__gnu_cxx)
// Available locking policies:
// _S_single single-threaded code that doesn't need to be locked.
// _S_mutex multi-threaded code that requires additional support
// from gthr.h or abstraction layers in concurrence.h.
// _S_atomic multi-threaded code using atomic operations.
enum _Lock_policy { _S_single, _S_mutex, _S_atomic };
// Compile time constant that indicates prefered locking policy in
// the current configuration.
static const _Lock_policy __default_lock_policy =
#ifdef __GTHREADS
// NB: This macro doesn't actually exist yet in the compiler, but is
// set somewhat haphazardly at configure time.
#ifdef _GLIBCXX_ATOMIC_BUILTINS
_S_atomic;
#else
_S_mutex;
#endif
#else
_S_single;
#endif
// NB: As this is used in libsupc++, need to only depend on
// exception. No stdexception classes, no use of std::string.
class __concurrence_lock_error : public std::exception
{
public:
virtual char const*
what() const throw()
{ return "__gnu_cxx::__concurrence_lock_error"; }
};
class __concurrence_unlock_error : public std::exception
{
public:
virtual char const*
what() const throw()
{ return "__gnu_cxx::__concurrence_unlock_error"; }
};
// Substitute for concurrence_error object in the case of -fno-exceptions.
inline void
__throw_concurrence_lock_error()
{
#if __EXCEPTIONS
throw __concurrence_lock_error();
#else
std::abort();
#endif
}
inline void
__throw_concurrence_unlock_error()
{
#if __EXCEPTIONS
throw __concurrence_unlock_error();
#else
std::abort();
#endif
}
class __mutex
{
private:
__gthread_mutex_t _M_mutex;
__mutex(const __mutex&);
__mutex& operator=(const __mutex&);
public:
__mutex()
{
#if __GTHREADS
if (__gthread_active_p())
{
#if defined __GTHREAD_MUTEX_INIT
__gthread_mutex_t __tmp = __GTHREAD_MUTEX_INIT;
_M_mutex = __tmp;
#else
__GTHREAD_MUTEX_INIT_FUNCTION(&_M_mutex);
#endif
}
#endif
}
void lock()
{
#if __GTHREADS
if (__gthread_active_p())
{
if (__gthread_mutex_lock(&_M_mutex) != 0)
__throw_concurrence_lock_error();
}
#endif
}
void unlock()
{
#if __GTHREADS
if (__gthread_active_p())
{
if (__gthread_mutex_unlock(&_M_mutex) != 0)
__throw_concurrence_unlock_error();
}
#endif
}
};
class __recursive_mutex
{
private:
__gthread_recursive_mutex_t _M_mutex;
__recursive_mutex(const __recursive_mutex&);
__recursive_mutex& operator=(const __recursive_mutex&);
public:
__recursive_mutex()
{
#if __GTHREADS
if (__gthread_active_p())
{
#if defined __GTHREAD_RECURSIVE_MUTEX_INIT
__gthread_recursive_mutex_t __tmp = __GTHREAD_RECURSIVE_MUTEX_INIT;
_M_mutex = __tmp;
#else
__GTHREAD_RECURSIVE_MUTEX_INIT_FUNCTION(&_M_mutex);
#endif
}
#endif
}
void lock()
{
#if __GTHREADS
if (__gthread_active_p())
{
if (__gthread_recursive_mutex_lock(&_M_mutex) != 0)
__throw_concurrence_lock_error();
}
#endif
}
void unlock()
{
#if __GTHREADS
if (__gthread_active_p())
{
if (__gthread_recursive_mutex_unlock(&_M_mutex) != 0)
__throw_concurrence_unlock_error();
}
#endif
}
};
/// @brief Scoped lock idiom.
// Acquire the mutex here with a constructor call, then release with
// the destructor call in accordance with RAII style.
class __scoped_lock
{
public:
typedef __mutex __mutex_type;
private:
__mutex_type& _M_device;
__scoped_lock(const __scoped_lock&);
__scoped_lock& operator=(const __scoped_lock&);
public:
explicit __scoped_lock(__mutex_type& __name) : _M_device(__name)
{ _M_device.lock(); }
~__scoped_lock() throw()
{ _M_device.unlock(); }
};
_GLIBCXX_END_NAMESPACE
#endif
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