/* * 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.// 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;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() {    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};#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: