stl_threads.h

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/*
 * 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 [e-mail].
#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;