/*
* 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.
// GCC extension begin
// In order to present a stable threading configuration, in all cases,
// gcc looks for it's own abstraction layer before all others. All
// modifications to this file are marked to allow easier importation of
// STL upgrades.
#if defined(__STL_GTHREADS)
#include "bits/gthr.h"
#else
// GCC extension end
#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
// GCC extension begin
#endif
// GCC extension end
namespace std
{
// 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
// GCC extension begin
#ifdef __STL_GTHREADS
__gthread_mutex_t _M_ref_count_lock;
_Refcount_Base(_RC_t __n) : _M_ref_count(__n)
{
#ifdef __GTHREAD_MUTEX_INIT
__gthread_mutex_t __tmp = __GTHREAD_MUTEX_INIT;
_M_ref_count_lock = __tmp;
#elif defined(__GTHREAD_MUTEX_INIT_FUNCTION)
__GTHREAD_MUTEX_INIT_FUNCTION (&_M_ref_count_lock);
#else
#error __GTHREAD_MUTEX_INIT or __GTHREAD_MUTEX_INIT_FUNCTION should be defined by gthr.h abstraction layer, report problem to libstdc++@gcc.gnu.org.
#endif
}
#else
// GCC extension end
# 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
// GCC extension begin
#endif
// GCC extension end
// GCC extension begin
#ifdef __STL_GTHREADS
void _M_incr() {
__gthread_mutex_lock(&_M_ref_count_lock);
++_M_ref_count;
__gthread_mutex_unlock(&_M_ref_count_lock);
}
_RC_t _M_decr() {
__gthread_mutex_lock(&_M_ref_count_lock);
volatile _RC_t __tmp = --_M_ref_count;
__gthread_mutex_unlock(&_M_ref_count_lock);
return __tmp;
}
#else
// GCC extension end
// _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
// GCC extension begin
#endif
// GCC extension end
};
// 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.
// GCC extension begin
#ifdef __STL_GTHREADS
// We don't provide an _Atomic_swap in this configuration. This only
// affects the use of ext/rope with threads. Someone could add this
// later, if required. You can start by cloning the __STL_PTHREADS
// path while making the obvious changes. Later it could be optimized
// to use the atomicity.h abstraction layer from libstdc++-v3.
#else
// GCC extension end
# 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
// GCC extension begin
#endif
// GCC extension end
// 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.
// Helper struct. This is a workaround for various compilers that don't
// handle static variables in inline functions properly.
template <int __inst>
struct _STL_mutex_spin {
enum { __low_max = 30, __high_max = 1000 };
// Low if we suspect uniprocessor, high for multiprocessor.
static unsigned __max;
static unsigned __last;
};
template <int __inst>
unsigned _STL_mutex_spin<__inst>::__max = _STL_mutex_spin<__inst>::__low_max;
template <int __inst>
unsigned _STL_mutex_spin<__inst>::__last = 0;
// GCC extension begin
#if defined(__STL_GTHREADS)
#if !defined(__GTHREAD_MUTEX_INIT) && defined(__GTHREAD_MUTEX_INIT_FUNCTION)
extern __gthread_mutex_t _GLIBCPP_mutex;
extern __gthread_mutex_t *_GLIBCPP_mutex_address;
extern __gthread_once_t _GLIBCPP_once;
extern void _GLIBCPP_mutex_init (void);
extern void _GLIBCPP_mutex_address_init (void);
#endif
#endif
// GCC extension end
struct _STL_mutex_lock
{
// GCC extension begin
#if defined(__STL_GTHREADS)
// The class must be statically initialized with __STL_MUTEX_INITIALIZER.
#if !defined(__GTHREAD_MUTEX_INIT) && defined(__GTHREAD_MUTEX_INIT_FUNCTION)
volatile int _M_init_flag;
__gthread_once_t _M_once;
#endif
__gthread_mutex_t _M_lock;
void _M_initialize() {
#ifdef __GTHREAD_MUTEX_INIT
// There should be no code in this path given the usage rules above.
#elif defined(__GTHREAD_MUTEX_INIT_FUNCTION)
if (_M_init_flag) return;
if (__gthread_once (&_GLIBCPP_once, _GLIBCPP_mutex_init) != 0
&& __gthread_active_p ())
abort ();
__gthread_mutex_lock (&_GLIBCPP_mutex);
if (!_M_init_flag) {
// Even though we have a global lock, we use __gthread_once to be
// absolutely certain the _M_lock mutex is only initialized once on
// multiprocessor systems.
_GLIBCPP_mutex_address = &_M_lock;
if (__gthread_once (&_M_once, _GLIBCPP_mutex_address_init) != 0
&& __gthread_active_p ())
abort ();
_M_init_flag = 1;
}
__gthread_mutex_unlock (&_GLIBCPP_mutex);
#endif
}
void _M_acquire_lock() {
#if !defined(__GTHREAD_MUTEX_INIT) && defined(__GTHREAD_MUTEX_INIT_FUNCTION)
if (!_M_init_flag) _M_initialize();
#endif
__gthread_mutex_lock(&_M_lock);
}
void _M_release_lock() {
#if !defined(__GTHREAD_MUTEX_INIT) && defined(__GTHREAD_MUTEX_INIT_FUNCTION)
if (!_M_init_flag) _M_initialize();
#endif
__gthread_mutex_unlock(&_M_lock);
}
#else
// GCC extension end
#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 = 1L << __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() {
volatile unsigned long* __lock = &this->_M_lock;
if (!_Atomic_swap((unsigned long*)__lock, 1)) {
return;
}
unsigned __my_spin_max = _STL_mutex_spin<0>::__max;
unsigned __my_last_spins = _STL_mutex_spin<0>::__last;
volatile unsigned __junk = 17; // Value doesn't matter.
unsigned __i;
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.
_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: