mirror of git://gcc.gnu.org/git/gcc.git
376 lines
12 KiB
C++
376 lines
12 KiB
C++
/*
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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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// WARNING: This is an internal header file, included by other C++
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// standard library headers. You should not attempt to use this header
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// file directly.
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// Stl_config.h should be included before this file.
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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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#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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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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# 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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// _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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};
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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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# 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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// 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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struct _STL_mutex_lock
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{
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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;
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_STL_mutex_spin<0>::__max = _STL_mutex_spin<0>::__high_max;
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return;
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}
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}
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// We are probably being scheduled against the other process. Sleep.
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_STL_mutex_spin<0>::__max = _STL_mutex_spin<0>::__low_max;
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for (__i = 0 ;; ++__i) {
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int __log_nsec = __i + 6;
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if (__log_nsec > 27) __log_nsec = 27;
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if (!_Atomic_swap((unsigned long *)__lock, 1)) {
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return;
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}
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_S_nsec_sleep(__log_nsec);
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}
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}
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void _M_release_lock() {
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volatile unsigned long* __lock = &_M_lock;
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# if defined(__STL_SGI_THREADS) && defined(__GNUC__) && __mips >= 3
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asm("sync");
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*__lock = 0;
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# elif defined(__STL_SGI_THREADS) && __mips >= 3 \
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&& (defined (_ABIN32) || defined(_ABI64))
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__lock_release(__lock);
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# else
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*__lock = 0;
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// This is not sufficient on many multiprocessors, since
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// writes to protected variables and the lock may be reordered.
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# endif
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}
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// We no longer use win32 critical sections.
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// They appear to be slower in the contention-free case,
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// and they appear difficult to initialize without introducing a race.
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#elif defined(__STL_PTHREADS)
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pthread_mutex_t _M_lock;
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void _M_initialize() { pthread_mutex_init(&_M_lock, NULL); }
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void _M_acquire_lock() { pthread_mutex_lock(&_M_lock); }
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void _M_release_lock() { pthread_mutex_unlock(&_M_lock); }
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#elif defined(__STL_UITHREADS)
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mutex_t _M_lock;
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void _M_initialize() { mutex_init(&_M_lock, USYNC_THREAD, 0); }
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void _M_acquire_lock() { mutex_lock(&_M_lock); }
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void _M_release_lock() { mutex_unlock(&_M_lock); }
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#else /* No threads */
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void _M_initialize() {}
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void _M_acquire_lock() {}
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void _M_release_lock() {}
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#endif
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};
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#ifdef __STL_PTHREADS
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// Pthreads locks must be statically initialized to something other than
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// the default value of zero.
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# define __STL_MUTEX_INITIALIZER = { PTHREAD_MUTEX_INITIALIZER }
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#elif defined(__STL_UITHREADS)
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// UIthreads locks must be statically initialized to something other than
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// the default value of zero.
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# define __STL_MUTEX_INITIALIZER = { DEFAULTMUTEX }
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#elif defined(__STL_SGI_THREADS) || defined(__STL_WIN32THREADS)
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# define __STL_MUTEX_INITIALIZER = { 0 }
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#else
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# define __STL_MUTEX_INITIALIZER
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#endif
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// A locking class that uses _STL_mutex_lock. The constructor takes a
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// reference to an _STL_mutex_lock, and acquires a lock. The
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// destructor releases the lock. It's not clear that this is exactly
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// the right functionality. It will probably change in the future.
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struct _STL_auto_lock
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{
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_STL_mutex_lock& _M_lock;
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_STL_auto_lock(_STL_mutex_lock& __lock) : _M_lock(__lock)
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{ _M_lock._M_acquire_lock(); }
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~_STL_auto_lock() { _M_lock._M_release_lock(); }
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private:
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void operator=(const _STL_auto_lock&);
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_STL_auto_lock(const _STL_auto_lock&);
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};
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} // namespace std
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#endif /* __SGI_STL_INTERNAL_THREADS_H */
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// Local Variables:
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// mode:C++
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// End:
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