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1b5e9d7e1b
* include/bits/stl_threads.h (_Atomic_swap): Only enable path
when platform supports __GTHREAD_MUTEX_INIT.
From-SVN: r46725
564 lines
19 KiB
C++
564 lines
19 KiB
C++
// Threading support -*- C++ -*-
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// Copyright (C) 2001 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 2, 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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// You should have received a copy of the GNU General Public License along
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// with this library; see the file COPYING. If not, write to the Free
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// Software Foundation, 59 Temple Place - Suite 330, Boston, MA 02111-1307,
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// USA.
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// As a special exception, you may use this file as part of a free software
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// library without restriction. Specifically, if other files instantiate
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// templates or use macros or inline functions from this file, or you compile
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// this file and link it with other files to produce an executable, this
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// file does not by itself cause the resulting executable to be covered by
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// the GNU General Public License. This exception does not however
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// invalidate any other reasons why the executable file might be covered by
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// the GNU General Public License.
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/*
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* Copyright (c) 1997-1999
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* Silicon Graphics Computer Systems, Inc.
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*
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* Permission to use, copy, modify, distribute and sell this software
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* and its documentation for any purpose is hereby granted without fee,
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* provided that the above copyright notice appear in all copies and
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* that both that copyright notice and this permission notice appear
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* in supporting documentation. Silicon Graphics makes no
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* representations about the suitability of this software for any
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* purpose. It is provided "as is" without express or implied warranty.
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*/
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/** @file stl_threads.h
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* This is an internal header file, included by other library headers.
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* You should not attempt to use it directly.
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*/
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#ifndef __SGI_STL_INTERNAL_THREADS_H
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#define __SGI_STL_INTERNAL_THREADS_H
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// Supported threading models are native SGI, pthreads, uithreads
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// (similar to pthreads, but based on an earlier draft of the Posix
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// threads standard), and Win32 threads. Uithread support by Jochen
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// Schlick, 1999.
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// GCC extension begin
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// In order to present a stable threading configuration, in all cases,
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// gcc looks for it's own abstraction layer before all others. All
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// modifications to this file are marked to allow easier importation of
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// STL upgrades.
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#if defined(__STL_GTHREADS)
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#include "bits/gthr.h"
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#else
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// GCC extension end
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#if defined(__STL_SGI_THREADS)
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#include <mutex.h>
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#include <time.h>
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#elif defined(__STL_PTHREADS)
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#include <pthread.h>
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#elif defined(__STL_UITHREADS)
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#include <thread.h>
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#include <synch.h>
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#elif defined(__STL_WIN32THREADS)
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#include <windows.h>
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#endif
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// GCC extension begin
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#endif
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// GCC extension end
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namespace std
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{
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// Class _Refcount_Base provides a type, _RC_t, a data member,
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// _M_ref_count, and member functions _M_incr and _M_decr, which perform
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// atomic preincrement/predecrement. The constructor initializes
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// _M_ref_count.
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// Hack for SGI o32 compilers.
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#if defined(__STL_SGI_THREADS) && !defined(__add_and_fetch) && \
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(__mips < 3 || !(defined (_ABIN32) || defined(_ABI64)))
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# define __add_and_fetch(__l,__v) add_then_test((unsigned long*)__l,__v)
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# define __test_and_set(__l,__v) test_and_set(__l,__v)
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#endif /* o32 */
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struct _Refcount_Base
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{
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// The type _RC_t
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# ifdef __STL_WIN32THREADS
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typedef long _RC_t;
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# else
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typedef size_t _RC_t;
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#endif
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// The data member _M_ref_count
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volatile _RC_t _M_ref_count;
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// Constructor
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// GCC extension begin
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#ifdef __STL_GTHREADS
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__gthread_mutex_t _M_ref_count_lock;
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_Refcount_Base(_RC_t __n) : _M_ref_count(__n)
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{
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#ifdef __GTHREAD_MUTEX_INIT
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__gthread_mutex_t __tmp = __GTHREAD_MUTEX_INIT;
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_M_ref_count_lock = __tmp;
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#elif defined(__GTHREAD_MUTEX_INIT_FUNCTION)
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__GTHREAD_MUTEX_INIT_FUNCTION (&_M_ref_count_lock);
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#else
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#error __GTHREAD_MUTEX_INIT or __GTHREAD_MUTEX_INIT_FUNCTION should be defined by gthr.h abstraction layer, report problem to libstdc++@gcc.gnu.org.
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#endif
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}
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#else
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// GCC extension end
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# ifdef __STL_PTHREADS
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pthread_mutex_t _M_ref_count_lock;
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_Refcount_Base(_RC_t __n) : _M_ref_count(__n)
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{ pthread_mutex_init(&_M_ref_count_lock, 0); }
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# elif defined(__STL_UITHREADS)
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mutex_t _M_ref_count_lock;
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_Refcount_Base(_RC_t __n) : _M_ref_count(__n)
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{ mutex_init(&_M_ref_count_lock, USYNC_THREAD, 0); }
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# else
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_Refcount_Base(_RC_t __n) : _M_ref_count(__n) {}
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# endif
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// GCC extension begin
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#endif
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// GCC extension end
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// GCC extension begin
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#ifdef __STL_GTHREADS
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void _M_incr() {
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__gthread_mutex_lock(&_M_ref_count_lock);
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++_M_ref_count;
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__gthread_mutex_unlock(&_M_ref_count_lock);
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}
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_RC_t _M_decr() {
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__gthread_mutex_lock(&_M_ref_count_lock);
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volatile _RC_t __tmp = --_M_ref_count;
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__gthread_mutex_unlock(&_M_ref_count_lock);
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return __tmp;
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}
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#else
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// GCC extension end
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// _M_incr and _M_decr
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# ifdef __STL_SGI_THREADS
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void _M_incr() { __add_and_fetch(&_M_ref_count, 1); }
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_RC_t _M_decr() { return __add_and_fetch(&_M_ref_count, (size_t) -1); }
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# elif defined (__STL_WIN32THREADS)
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void _M_incr() { InterlockedIncrement((_RC_t*)&_M_ref_count); }
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_RC_t _M_decr() { return InterlockedDecrement((_RC_t*)&_M_ref_count); }
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# elif defined(__STL_PTHREADS)
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void _M_incr() {
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pthread_mutex_lock(&_M_ref_count_lock);
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++_M_ref_count;
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pthread_mutex_unlock(&_M_ref_count_lock);
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}
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_RC_t _M_decr() {
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pthread_mutex_lock(&_M_ref_count_lock);
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volatile _RC_t __tmp = --_M_ref_count;
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pthread_mutex_unlock(&_M_ref_count_lock);
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return __tmp;
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}
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# elif defined(__STL_UITHREADS)
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void _M_incr() {
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mutex_lock(&_M_ref_count_lock);
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++_M_ref_count;
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mutex_unlock(&_M_ref_count_lock);
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}
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_RC_t _M_decr() {
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mutex_lock(&_M_ref_count_lock);
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/*volatile*/ _RC_t __tmp = --_M_ref_count;
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mutex_unlock(&_M_ref_count_lock);
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return __tmp;
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}
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# else /* No threads */
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void _M_incr() { ++_M_ref_count; }
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_RC_t _M_decr() { return --_M_ref_count; }
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# endif
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// GCC extension begin
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#endif
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// GCC extension end
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};
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// Atomic swap on unsigned long
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// This is guaranteed to behave as though it were atomic only if all
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// possibly concurrent updates use _Atomic_swap.
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// In some cases the operation is emulated with a lock.
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// GCC extension begin
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#if defined (__STL_GTHREADS) && defined (__GTHREAD_MUTEX_INIT)
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// We don't provide an _Atomic_swap in this configuration. This only
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// affects the use of ext/rope with threads. Someone could add this
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// later, if required. You can start by cloning the __STL_PTHREADS
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// path while making the obvious changes. Later it could be optimized
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// to use the atomicity.h abstraction layer from libstdc++-v3.
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// vyzo: simple _Atomic_swap implementation following the guidelines above
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// We use a template here only to get a unique initialized instance.
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template<int __dummy>
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struct _Swap_lock_struct {
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static __gthread_mutex_t _S_swap_lock;
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};
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template<int __dummy>
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__gthread_mutex_t
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_Swap_lock_struct<__dummy>::_S_swap_lock = __GTHREAD_MUTEX_INIT;
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// This should be portable, but performance is expected
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// to be quite awful. This really needs platform specific
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// code.
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inline unsigned long _Atomic_swap(unsigned long * __p, unsigned long __q) {
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__gthread_mutex_lock(&_Swap_lock_struct<0>::_S_swap_lock);
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unsigned long __result = *__p;
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*__p = __q;
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__gthread_mutex_unlock(&_Swap_lock_struct<0>::_S_swap_lock);
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return __result;
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}
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#else
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// GCC extension end
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# ifdef __STL_SGI_THREADS
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inline unsigned long _Atomic_swap(unsigned long * __p, unsigned long __q) {
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# if __mips < 3 || !(defined (_ABIN32) || defined(_ABI64))
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return test_and_set(__p, __q);
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# else
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return __test_and_set(__p, (unsigned long)__q);
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# endif
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}
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# elif defined(__STL_WIN32THREADS)
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inline unsigned long _Atomic_swap(unsigned long * __p, unsigned long __q) {
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return (unsigned long) InterlockedExchange((LPLONG)__p, (LONG)__q);
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}
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# elif defined(__STL_PTHREADS)
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// We use a template here only to get a unique initialized instance.
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template<int __dummy>
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struct _Swap_lock_struct {
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static pthread_mutex_t _S_swap_lock;
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};
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template<int __dummy>
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pthread_mutex_t
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_Swap_lock_struct<__dummy>::_S_swap_lock = PTHREAD_MUTEX_INITIALIZER;
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// This should be portable, but performance is expected
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// to be quite awful. This really needs platform specific
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// code.
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inline unsigned long _Atomic_swap(unsigned long * __p, unsigned long __q) {
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pthread_mutex_lock(&_Swap_lock_struct<0>::_S_swap_lock);
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unsigned long __result = *__p;
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*__p = __q;
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pthread_mutex_unlock(&_Swap_lock_struct<0>::_S_swap_lock);
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return __result;
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}
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# elif defined(__STL_UITHREADS)
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// We use a template here only to get a unique initialized instance.
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template<int __dummy>
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struct _Swap_lock_struct {
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static mutex_t _S_swap_lock;
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};
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template<int __dummy>
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mutex_t
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_Swap_lock_struct<__dummy>::_S_swap_lock = DEFAULTMUTEX;
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// This should be portable, but performance is expected
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// to be quite awful. This really needs platform specific
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// code.
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inline unsigned long _Atomic_swap(unsigned long * __p, unsigned long __q) {
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mutex_lock(&_Swap_lock_struct<0>::_S_swap_lock);
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unsigned long __result = *__p;
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*__p = __q;
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mutex_unlock(&_Swap_lock_struct<0>::_S_swap_lock);
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return __result;
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}
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# elif defined (__STL_SOLARIS_THREADS)
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// any better solutions ?
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// We use a template here only to get a unique initialized instance.
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template<int __dummy>
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struct _Swap_lock_struct {
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static mutex_t _S_swap_lock;
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};
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# if ( __STL_STATIC_TEMPLATE_DATA > 0 )
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template<int __dummy>
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mutex_t
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_Swap_lock_struct<__dummy>::_S_swap_lock = DEFAULTMUTEX;
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# else
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__DECLARE_INSTANCE(mutex_t, _Swap_lock_struct<__dummy>::_S_swap_lock,
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=DEFAULTMUTEX);
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# endif /* ( __STL_STATIC_TEMPLATE_DATA > 0 ) */
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// This should be portable, but performance is expected
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// to be quite awful. This really needs platform specific
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// code.
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inline unsigned long _Atomic_swap(unsigned long * __p, unsigned long __q) {
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mutex_lock(&_Swap_lock_struct<0>::_S_swap_lock);
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unsigned long __result = *__p;
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*__p = __q;
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mutex_unlock(&_Swap_lock_struct<0>::_S_swap_lock);
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return __result;
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}
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# else
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static inline unsigned long _Atomic_swap(unsigned long * __p, unsigned long __q) {
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unsigned long __result = *__p;
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*__p = __q;
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return __result;
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}
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# endif
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// GCC extension begin
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#endif
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// GCC extension end
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// Locking class. Note that this class *does not have a constructor*.
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// It must be initialized either statically, with __STL_MUTEX_INITIALIZER,
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// or dynamically, by explicitly calling the _M_initialize member function.
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// (This is similar to the ways that a pthreads mutex can be initialized.)
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// There are explicit member functions for acquiring and releasing the lock.
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// There is no constructor because static initialization is essential for
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// some uses, and only a class aggregate (see section 8.5.1 of the C++
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// standard) can be initialized that way. That means we must have no
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// constructors, no base classes, no virtual functions, and no private or
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// protected members.
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// Helper struct. This is a workaround for various compilers that don't
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// handle static variables in inline functions properly.
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template <int __inst>
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struct _STL_mutex_spin {
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enum { __low_max = 30, __high_max = 1000 };
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// Low if we suspect uniprocessor, high for multiprocessor.
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static unsigned __max;
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static unsigned __last;
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};
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template <int __inst>
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unsigned _STL_mutex_spin<__inst>::__max = _STL_mutex_spin<__inst>::__low_max;
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template <int __inst>
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unsigned _STL_mutex_spin<__inst>::__last = 0;
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// GCC extension begin
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#if defined(__STL_GTHREADS)
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#if !defined(__GTHREAD_MUTEX_INIT) && defined(__GTHREAD_MUTEX_INIT_FUNCTION)
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extern __gthread_mutex_t _GLIBCPP_mutex;
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extern __gthread_mutex_t *_GLIBCPP_mutex_address;
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extern __gthread_once_t _GLIBCPP_once;
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extern void _GLIBCPP_mutex_init (void);
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extern void _GLIBCPP_mutex_address_init (void);
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#endif
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#endif
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// GCC extension end
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struct _STL_mutex_lock
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{
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// GCC extension begin
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#if defined(__STL_GTHREADS)
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// The class must be statically initialized with __STL_MUTEX_INITIALIZER.
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#if !defined(__GTHREAD_MUTEX_INIT) && defined(__GTHREAD_MUTEX_INIT_FUNCTION)
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volatile int _M_init_flag;
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__gthread_once_t _M_once;
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#endif
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__gthread_mutex_t _M_lock;
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void _M_initialize() {
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#ifdef __GTHREAD_MUTEX_INIT
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// There should be no code in this path given the usage rules above.
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#elif defined(__GTHREAD_MUTEX_INIT_FUNCTION)
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if (_M_init_flag) return;
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if (__gthread_once (&_GLIBCPP_once, _GLIBCPP_mutex_init) != 0
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&& __gthread_active_p ())
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abort ();
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__gthread_mutex_lock (&_GLIBCPP_mutex);
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if (!_M_init_flag) {
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// Even though we have a global lock, we use __gthread_once to be
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// absolutely certain the _M_lock mutex is only initialized once on
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// multiprocessor systems.
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_GLIBCPP_mutex_address = &_M_lock;
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if (__gthread_once (&_M_once, _GLIBCPP_mutex_address_init) != 0
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&& __gthread_active_p ())
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abort ();
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_M_init_flag = 1;
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}
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__gthread_mutex_unlock (&_GLIBCPP_mutex);
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#endif
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}
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void _M_acquire_lock() {
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#if !defined(__GTHREAD_MUTEX_INIT) && defined(__GTHREAD_MUTEX_INIT_FUNCTION)
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if (!_M_init_flag) _M_initialize();
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#endif
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__gthread_mutex_lock(&_M_lock);
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}
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void _M_release_lock() {
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#if !defined(__GTHREAD_MUTEX_INIT) && defined(__GTHREAD_MUTEX_INIT_FUNCTION)
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if (!_M_init_flag) _M_initialize();
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#endif
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__gthread_mutex_unlock(&_M_lock);
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}
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#else
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// GCC extension end
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#if defined(__STL_SGI_THREADS) || defined(__STL_WIN32THREADS)
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// It should be relatively easy to get this to work on any modern Unix.
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volatile unsigned long _M_lock;
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void _M_initialize() { _M_lock = 0; }
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static void _S_nsec_sleep(int __log_nsec) {
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# ifdef __STL_SGI_THREADS
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struct timespec __ts;
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/* Max sleep is 2**27nsec ~ 60msec */
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__ts.tv_sec = 0;
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__ts.tv_nsec = 1L << __log_nsec;
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nanosleep(&__ts, 0);
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# elif defined(__STL_WIN32THREADS)
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if (__log_nsec <= 20) {
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Sleep(0);
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} else {
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Sleep(1 << (__log_nsec - 20));
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}
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# else
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# error unimplemented
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# endif
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}
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void _M_acquire_lock() {
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volatile unsigned long* __lock = &this->_M_lock;
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if (!_Atomic_swap((unsigned long*)__lock, 1)) {
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return;
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}
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unsigned __my_spin_max = _STL_mutex_spin<0>::__max;
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unsigned __my_last_spins = _STL_mutex_spin<0>::__last;
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volatile unsigned __junk = 17; // Value doesn't matter.
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unsigned __i;
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for (__i = 0; __i < __my_spin_max; __i++) {
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if (__i < __my_last_spins/2 || *__lock) {
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__junk *= __junk; __junk *= __junk;
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__junk *= __junk; __junk *= __junk;
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continue;
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}
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if (!_Atomic_swap((unsigned long*)__lock, 1)) {
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// got it!
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// Spinning worked. Thus we're probably not being scheduled
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// against the other process with which we were contending.
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// Thus it makes sense to spin longer the next time.
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_STL_mutex_spin<0>::__last = __i;
|
|
_STL_mutex_spin<0>::__max = _STL_mutex_spin<0>::__high_max;
|
|
return;
|
|
}
|
|
}
|
|
// We are probably being scheduled against the other process. Sleep.
|
|
_STL_mutex_spin<0>::__max = _STL_mutex_spin<0>::__low_max;
|
|
for (__i = 0 ;; ++__i) {
|
|
int __log_nsec = __i + 6;
|
|
|
|
if (__log_nsec > 27) __log_nsec = 27;
|
|
if (!_Atomic_swap((unsigned long *)__lock, 1)) {
|
|
return;
|
|
}
|
|
_S_nsec_sleep(__log_nsec);
|
|
}
|
|
}
|
|
void _M_release_lock() {
|
|
volatile unsigned long* __lock = &_M_lock;
|
|
# if defined(__STL_SGI_THREADS) && defined(__GNUC__) && __mips >= 3
|
|
asm("sync");
|
|
*__lock = 0;
|
|
# elif defined(__STL_SGI_THREADS) && __mips >= 3 \
|
|
&& (defined (_ABIN32) || defined(_ABI64))
|
|
__lock_release(__lock);
|
|
# else
|
|
*__lock = 0;
|
|
// This is not sufficient on many multiprocessors, since
|
|
// writes to protected variables and the lock may be reordered.
|
|
# endif
|
|
}
|
|
|
|
// We no longer use win32 critical sections.
|
|
// They appear to be slower in the contention-free case,
|
|
// and they appear difficult to initialize without introducing a race.
|
|
|
|
#elif defined(__STL_PTHREADS)
|
|
pthread_mutex_t _M_lock;
|
|
void _M_initialize() { pthread_mutex_init(&_M_lock, NULL); }
|
|
void _M_acquire_lock() { pthread_mutex_lock(&_M_lock); }
|
|
void _M_release_lock() { pthread_mutex_unlock(&_M_lock); }
|
|
#elif defined(__STL_UITHREADS)
|
|
mutex_t _M_lock;
|
|
void _M_initialize() { mutex_init(&_M_lock, USYNC_THREAD, 0); }
|
|
void _M_acquire_lock() { mutex_lock(&_M_lock); }
|
|
void _M_release_lock() { mutex_unlock(&_M_lock); }
|
|
#else /* No threads */
|
|
void _M_initialize() {}
|
|
void _M_acquire_lock() {}
|
|
void _M_release_lock() {}
|
|
#endif
|
|
// GCC extension begin
|
|
#endif
|
|
// GCC extension end
|
|
};
|
|
|
|
// GCC extension begin
|
|
#if defined(__STL_GTHREADS)
|
|
#ifdef __GTHREAD_MUTEX_INIT
|
|
#define __STL_MUTEX_INITIALIZER = { __GTHREAD_MUTEX_INIT }
|
|
#elif defined(__GTHREAD_MUTEX_INIT_FUNCTION)
|
|
#ifdef __GTHREAD_MUTEX_INIT_DEFAULT
|
|
#define __STL_MUTEX_INITIALIZER \
|
|
= { 0, __GTHREAD_ONCE_INIT, __GTHREAD_MUTEX_INIT_DEFAULT }
|
|
#else
|
|
#define __STL_MUTEX_INITIALIZER = { 0, __GTHREAD_ONCE_INIT }
|
|
#endif
|
|
#endif
|
|
#else
|
|
// GCC extension end
|
|
#ifdef __STL_PTHREADS
|
|
// Pthreads locks must be statically initialized to something other than
|
|
// the default value of zero.
|
|
# define __STL_MUTEX_INITIALIZER = { PTHREAD_MUTEX_INITIALIZER }
|
|
#elif defined(__STL_UITHREADS)
|
|
// UIthreads locks must be statically initialized to something other than
|
|
// the default value of zero.
|
|
# define __STL_MUTEX_INITIALIZER = { DEFAULTMUTEX }
|
|
#elif defined(__STL_SGI_THREADS) || defined(__STL_WIN32THREADS)
|
|
# define __STL_MUTEX_INITIALIZER = { 0 }
|
|
#else
|
|
# define __STL_MUTEX_INITIALIZER
|
|
#endif
|
|
// GCC extension begin
|
|
#endif
|
|
// GCC extension end
|
|
|
|
|
|
// A locking class that uses _STL_mutex_lock. The constructor takes a
|
|
// reference to an _STL_mutex_lock, and acquires a lock. The
|
|
// destructor releases the lock. It's not clear that this is exactly
|
|
// the right functionality. It will probably change in the future.
|
|
|
|
struct _STL_auto_lock
|
|
{
|
|
_STL_mutex_lock& _M_lock;
|
|
|
|
_STL_auto_lock(_STL_mutex_lock& __lock) : _M_lock(__lock)
|
|
{ _M_lock._M_acquire_lock(); }
|
|
~_STL_auto_lock() { _M_lock._M_release_lock(); }
|
|
|
|
private:
|
|
void operator=(const _STL_auto_lock&);
|
|
_STL_auto_lock(const _STL_auto_lock&);
|
|
};
|
|
|
|
} // namespace std
|
|
|
|
#endif /* __SGI_STL_INTERNAL_THREADS_H */
|
|
|
|
// Local Variables:
|
|
// mode:C++
|
|
// End:
|
|
|