370 lines
12 KiB
C++
370 lines
12 KiB
C++
/*
|
|
* Copyright (c) 1997-1999
|
|
* Silicon Graphics Computer Systems, Inc.
|
|
*
|
|
* Permission to use, copy, modify, distribute and sell this software
|
|
* and its documentation for any purpose is hereby granted without fee,
|
|
* provided that the above copyright notice appear in all copies and
|
|
* that both that copyright notice and this permission notice appear
|
|
* in supporting documentation. Silicon Graphics makes no
|
|
* representations about the suitability of this software for any
|
|
* purpose. It is provided "as is" without express or implied warranty.
|
|
*/
|
|
|
|
// WARNING: This is an internal header file, included by other C++
|
|
// standard library headers. You should not attempt to use this header
|
|
// file directly.
|
|
// Stl_config.h should be included before this file.
|
|
|
|
#ifndef __SGI_STL_INTERNAL_THREADS_H
|
|
#define __SGI_STL_INTERNAL_THREADS_H
|
|
|
|
// Supported threading models are native SGI, pthreads, uithreads
|
|
// (similar to pthreads, but based on an earlier draft of the Posix
|
|
// threads standard), and Win32 threads. Uithread support by Jochen
|
|
// Schlick, 1999.
|
|
|
|
#if defined(__STL_SGI_THREADS)
|
|
#include <mutex.h>
|
|
#include <time.h>
|
|
#elif defined(__STL_PTHREADS)
|
|
#include <pthread.h>
|
|
#elif defined(__STL_UITHREADS)
|
|
#include <thread.h>
|
|
#include <synch.h>
|
|
#elif defined(__STL_WIN32THREADS)
|
|
#include <windows.h>
|
|
#endif
|
|
|
|
__STL_BEGIN_NAMESPACE
|
|
|
|
|
|
// Class _Refcount_Base provides a type, _RC_t, a data member,
|
|
// _M_ref_count, and member functions _M_incr and _M_decr, which perform
|
|
// atomic preincrement/predecrement. The constructor initializes
|
|
// _M_ref_count.
|
|
|
|
// Hack for SGI o32 compilers.
|
|
#if defined(__STL_SGI_THREADS) && !defined(__add_and_fetch) && \
|
|
(__mips < 3 || !(defined (_ABIN32) || defined(_ABI64)))
|
|
# define __add_and_fetch(__l,__v) add_then_test((unsigned long*)__l,__v)
|
|
# define __test_and_set(__l,__v) test_and_set(__l,__v)
|
|
#endif /* o32 */
|
|
|
|
struct _Refcount_Base
|
|
{
|
|
// The type _RC_t
|
|
# ifdef __STL_WIN32THREADS
|
|
typedef long _RC_t;
|
|
# else
|
|
typedef size_t _RC_t;
|
|
#endif
|
|
|
|
// The data member _M_ref_count
|
|
volatile _RC_t _M_ref_count;
|
|
|
|
// Constructor
|
|
# ifdef __STL_PTHREADS
|
|
pthread_mutex_t _M_ref_count_lock;
|
|
_Refcount_Base(_RC_t __n) : _M_ref_count(__n)
|
|
{ pthread_mutex_init(&_M_ref_count_lock, 0); }
|
|
# elif defined(__STL_UITHREADS)
|
|
mutex_t _M_ref_count_lock;
|
|
_Refcount_Base(_RC_t __n) : _M_ref_count(__n)
|
|
{ mutex_init(&_M_ref_count_lock, USYNC_THREAD, 0); }
|
|
# else
|
|
_Refcount_Base(_RC_t __n) : _M_ref_count(__n) {}
|
|
# endif
|
|
|
|
// _M_incr and _M_decr
|
|
# ifdef __STL_SGI_THREADS
|
|
void _M_incr() { __add_and_fetch(&_M_ref_count, 1); }
|
|
_RC_t _M_decr() { return __add_and_fetch(&_M_ref_count, (size_t) -1); }
|
|
# elif defined (__STL_WIN32THREADS)
|
|
void _M_incr() { InterlockedIncrement((_RC_t*)&_M_ref_count); }
|
|
_RC_t _M_decr() { return InterlockedDecrement((_RC_t*)&_M_ref_count); }
|
|
# elif defined(__STL_PTHREADS)
|
|
void _M_incr() {
|
|
pthread_mutex_lock(&_M_ref_count_lock);
|
|
++_M_ref_count;
|
|
pthread_mutex_unlock(&_M_ref_count_lock);
|
|
}
|
|
_RC_t _M_decr() {
|
|
pthread_mutex_lock(&_M_ref_count_lock);
|
|
volatile _RC_t __tmp = --_M_ref_count;
|
|
pthread_mutex_unlock(&_M_ref_count_lock);
|
|
return __tmp;
|
|
}
|
|
# elif defined(__STL_UITHREADS)
|
|
void _M_incr() {
|
|
mutex_lock(&_M_ref_count_lock);
|
|
++_M_ref_count;
|
|
mutex_unlock(&_M_ref_count_lock);
|
|
}
|
|
_RC_t _M_decr() {
|
|
mutex_lock(&_M_ref_count_lock);
|
|
/*volatile*/ _RC_t __tmp = --_M_ref_count;
|
|
mutex_unlock(&_M_ref_count_lock);
|
|
return __tmp;
|
|
}
|
|
# else /* No threads */
|
|
void _M_incr() { ++_M_ref_count; }
|
|
_RC_t _M_decr() { return --_M_ref_count; }
|
|
# endif
|
|
};
|
|
|
|
// Atomic swap on unsigned long
|
|
// This is guaranteed to behave as though it were atomic only if all
|
|
// possibly concurrent updates use _Atomic_swap.
|
|
// In some cases the operation is emulated with a lock.
|
|
# ifdef __STL_SGI_THREADS
|
|
inline unsigned long _Atomic_swap(unsigned long * __p, unsigned long __q) {
|
|
# if __mips < 3 || !(defined (_ABIN32) || defined(_ABI64))
|
|
return test_and_set(__p, __q);
|
|
# else
|
|
return __test_and_set(__p, (unsigned long)__q);
|
|
# endif
|
|
}
|
|
# elif defined(__STL_WIN32THREADS)
|
|
inline unsigned long _Atomic_swap(unsigned long * __p, unsigned long __q) {
|
|
return (unsigned long) InterlockedExchange((LPLONG)__p, (LONG)__q);
|
|
}
|
|
# elif defined(__STL_PTHREADS)
|
|
// We use a template here only to get a unique initialized instance.
|
|
template<int __dummy>
|
|
struct _Swap_lock_struct {
|
|
static pthread_mutex_t _S_swap_lock;
|
|
};
|
|
|
|
template<int __dummy>
|
|
pthread_mutex_t
|
|
_Swap_lock_struct<__dummy>::_S_swap_lock = PTHREAD_MUTEX_INITIALIZER;
|
|
|
|
// This should be portable, but performance is expected
|
|
// to be quite awful. This really needs platform specific
|
|
// code.
|
|
inline unsigned long _Atomic_swap(unsigned long * __p, unsigned long __q) {
|
|
pthread_mutex_lock(&_Swap_lock_struct<0>::_S_swap_lock);
|
|
unsigned long __result = *__p;
|
|
*__p = __q;
|
|
pthread_mutex_unlock(&_Swap_lock_struct<0>::_S_swap_lock);
|
|
return __result;
|
|
}
|
|
# elif defined(__STL_UITHREADS)
|
|
// We use a template here only to get a unique initialized instance.
|
|
template<int __dummy>
|
|
struct _Swap_lock_struct {
|
|
static mutex_t _S_swap_lock;
|
|
};
|
|
|
|
template<int __dummy>
|
|
mutex_t
|
|
_Swap_lock_struct<__dummy>::_S_swap_lock = DEFAULTMUTEX;
|
|
|
|
// This should be portable, but performance is expected
|
|
// to be quite awful. This really needs platform specific
|
|
// code.
|
|
inline unsigned long _Atomic_swap(unsigned long * __p, unsigned long __q) {
|
|
mutex_lock(&_Swap_lock_struct<0>::_S_swap_lock);
|
|
unsigned long __result = *__p;
|
|
*__p = __q;
|
|
mutex_unlock(&_Swap_lock_struct<0>::_S_swap_lock);
|
|
return __result;
|
|
}
|
|
# elif defined (__STL_SOLARIS_THREADS)
|
|
// any better solutions ?
|
|
// We use a template here only to get a unique initialized instance.
|
|
template<int __dummy>
|
|
struct _Swap_lock_struct {
|
|
static mutex_t _S_swap_lock;
|
|
};
|
|
|
|
# if ( __STL_STATIC_TEMPLATE_DATA > 0 )
|
|
template<int __dummy>
|
|
mutex_t
|
|
_Swap_lock_struct<__dummy>::_S_swap_lock = DEFAULTMUTEX;
|
|
# else
|
|
__DECLARE_INSTANCE(mutex_t, _Swap_lock_struct<__dummy>::_S_swap_lock,
|
|
=DEFAULTMUTEX);
|
|
# endif /* ( __STL_STATIC_TEMPLATE_DATA > 0 ) */
|
|
|
|
// This should be portable, but performance is expected
|
|
// to be quite awful. This really needs platform specific
|
|
// code.
|
|
inline unsigned long _Atomic_swap(unsigned long * __p, unsigned long __q) {
|
|
mutex_lock(&_Swap_lock_struct<0>::_S_swap_lock);
|
|
unsigned long __result = *__p;
|
|
*__p = __q;
|
|
mutex_unlock(&_Swap_lock_struct<0>::_S_swap_lock);
|
|
return __result;
|
|
}
|
|
# else
|
|
static inline unsigned long _Atomic_swap(unsigned long * __p, unsigned long __q) {
|
|
unsigned long __result = *__p;
|
|
*__p = __q;
|
|
return __result;
|
|
}
|
|
# endif
|
|
|
|
// Locking class. Note that this class *does not have a constructor*.
|
|
// It must be initialized either statically, with __STL_MUTEX_INITIALIZER,
|
|
// or dynamically, by explicitly calling the _M_initialize member function.
|
|
// (This is similar to the ways that a pthreads mutex can be initialized.)
|
|
// There are explicit member functions for acquiring and releasing the lock.
|
|
|
|
// There is no constructor because static initialization is essential for
|
|
// some uses, and only a class aggregate (see section 8.5.1 of the C++
|
|
// standard) can be initialized that way. That means we must have no
|
|
// constructors, no base classes, no virtual functions, and no private or
|
|
// protected members.
|
|
|
|
struct _STL_mutex_lock
|
|
{
|
|
#if defined(__STL_SGI_THREADS) || defined(__STL_WIN32THREADS)
|
|
// It should be relatively easy to get this to work on any modern Unix.
|
|
volatile unsigned long _M_lock;
|
|
void _M_initialize() { _M_lock = 0; }
|
|
static void _S_nsec_sleep(int __log_nsec) {
|
|
# ifdef __STL_SGI_THREADS
|
|
struct timespec __ts;
|
|
/* Max sleep is 2**27nsec ~ 60msec */
|
|
__ts.tv_sec = 0;
|
|
__ts.tv_nsec = 1 << __log_nsec;
|
|
nanosleep(&__ts, 0);
|
|
# elif defined(__STL_WIN32THREADS)
|
|
if (__log_nsec <= 20) {
|
|
Sleep(0);
|
|
} else {
|
|
Sleep(1 << (__log_nsec - 20));
|
|
}
|
|
# else
|
|
# error unimplemented
|
|
# endif
|
|
}
|
|
void _M_acquire_lock() {
|
|
const unsigned __low_spin_max = 30; // spins if we suspect uniprocessor
|
|
const unsigned __high_spin_max = 1000; // spins for multiprocessor
|
|
static unsigned __spin_max = __low_spin_max;
|
|
unsigned __my_spin_max;
|
|
static unsigned __last_spins = 0;
|
|
unsigned __my_last_spins;
|
|
volatile unsigned __junk;
|
|
int __i;
|
|
volatile unsigned long* __lock = &this->_M_lock;
|
|
|
|
if (!_Atomic_swap((unsigned long*)__lock, 1)) {
|
|
return;
|
|
}
|
|
__my_spin_max = __spin_max;
|
|
__my_last_spins = __last_spins;
|
|
__junk = 17; // Value doesn't matter.
|
|
for (__i = 0; __i < __my_spin_max; __i++) {
|
|
if (__i < __my_last_spins/2 || *__lock) {
|
|
__junk *= __junk; __junk *= __junk;
|
|
__junk *= __junk; __junk *= __junk;
|
|
continue;
|
|
}
|
|
if (!_Atomic_swap((unsigned long*)__lock, 1)) {
|
|
// got it!
|
|
// Spinning worked. Thus we're probably not being scheduled
|
|
// against the other process with which we were contending.
|
|
// Thus it makes sense to spin longer the next time.
|
|
__last_spins = __i;
|
|
__spin_max = __high_spin_max;
|
|
return;
|
|
}
|
|
}
|
|
// We are probably being scheduled against the other process. Sleep.
|
|
__spin_max = __low_spin_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
|
|
};
|
|
|
|
#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
|
|
|
|
|
|
// 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&);
|
|
};
|
|
|
|
__STL_END_NAMESPACE
|
|
|
|
#endif /* __SGI_STL_INTERNAL_THREADS_H */
|
|
|
|
// Local Variables:
|
|
// mode:C++
|
|
// End:
|
|
|
|
|
|
|
|
|
|
|