_threads.h

MONA是为数不多的C++语言编写的一个很小的操作系统

/*
 * Copyright (c) 1997-1999
 * Silicon Graphics Computer Systems, Inc.
 *
 * Copyright (c) 1999 
 * Boris Fomitchev
 *
 * This material is provided "as is", with absolutely no warranty expressed
 * or implied. Any use is at your own risk.
 *
 * Permission to use or copy this software for any purpose is hereby granted 
 * without fee, provided the above notices are retained on all copies.
 * Permission to modify the code and to distribute modified code is granted,
 * provided the above notices are retained, and a notice that the code was
 * modified is included with the above copyright notice.
 *
 */

// 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 _STLP_INTERNAL_THREADS_H
#define _STLP_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, and Solaris threads generalized to them.

#ifndef _STLP_CONFIG_H
#include <stl/_config.h>
#endif

# if ! defined (_STLP_CSTDDEF)
///#  include <cstddef>
# endif

# if ! defined (_STLP_CSTDLIB)
///#  include <cstdlib>
# endif

// On SUN and Mac OS X gcc, zero-initialization works just fine...
# if defined (__sun) || ( defined(__GNUC__) && defined(__APPLE__) )
# define _STLP_MUTEX_INITIALIZER
# endif

# if defined (_STLP_WIN32) || defined (__sgi) || defined (_STLP_SPARC_SOLARIS_THREADS)
  typedef long __stl_atomic_t;
# else 
# if defined (_STLP_USE_NAMESPACES) && ! defined (_STLP_VENDOR_GLOBAL_CSTD)
// using _STLP_VENDOR_CSTD::size_t;
using namespace _STLP_VENDOR_CSTD;
# endif
  typedef size_t __stl_atomic_t;
#endif  

# if defined(_STLP_SGI_THREADS)
#  include <mutex.h>
// Hack for SGI o32 compilers.
#if !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 */

# if __mips < 3 || !(defined (_ABIN32) || defined(_ABI64))
#  define _STLP_ATOMIC_EXCHANGE(__p, __q) test_and_set(__p, __q)
# else
#  define _STLP_ATOMIC_EXCHANGE(__p, __q) __test_and_set((unsigned long*)__p, (unsigned long)__q)
# endif

#  define _STLP_ATOMIC_INCREMENT(__x) __add_and_fetch(__x, 1)
#  define _STLP_ATOMIC_DECREMENT(__x) __add_and_fetch(__x, (size_t) -1)

# elif defined (__GNUC__) && defined (__i386__) && defined (__unix__) && defined (_STLP_USE_INLINE_X86_SPINLOCK) 

// gcc on i386 linux, freebsd, etc. 

// This enables the memory caching on x86 linux.  It is critical for SMP
// without it the performace is DISMAL!
static inline unsigned long __xchg(volatile __stl_atomic_t* target, int source)
{

  // The target is refernce in memory rather than the register
  // because making a copy of it from memory to the register and
  // back again would ruin the atomic nature of the call.
  // the source does not need to be delt with atomicly so it can
  // be copied about as needed.
  //
  // The casting of the source is used to prevent gcc from optimizing 
  // in such a way that breaks the atomic nature of this call.
  //
  __asm__ __volatile__("xchgl %1,%0"
		       :"=m" (*(volatile long *) target), "=r" (source)
		       :"m" (*(volatile long *) target), "r" (source) );
  return source;

  //  The assembly above does the following atomicly:
  //   int temp=source;
  //   source=(int)(*target);
  //   (int)(*target)=temp;
  // return source
}

static inline void __inc_and_fetch(volatile __stl_atomic_t* __x)
{
  // Referenced in memory rather than register to preserve the atomic nature.
  //
  __asm__ __volatile__(
      "lock; incl %0"
      :"=m" (*__x)
      :"m" (*__x) );

  //  The assembly above does the following atomicly:
  //   ++(int)(*__x);

}
static inline void __dec_and_fetch(volatile __stl_atomic_t* __x)
{
  // Referenced in memory rather than register to preserve the atomic nature.
  //
  __asm__ __volatile__(
      "lock; decl %0"
      :"=m" (*__x)
      :"m" (*__x) );

  //  The assembly above does the following atomicly:
  //   --(int)(*__x);
}

#  define _STLP_ATOMIC_EXCHANGE(target, newValue) ((__xchg(target, newValue)))
#  define _STLP_ATOMIC_INCREMENT(__x) __inc_and_fetch(__x)
#  define _STLP_ATOMIC_DECREMENT(__x) __dec_and_fetch(__x)

# elif defined(_STLP_PTHREADS)

#  include <pthread.h>
#  ifndef _STLP_USE_PTHREAD_SPINLOCK
#   if defined(PTHREAD_MUTEX_INITIALIZER) && !defined(_STLP_MUTEX_INITIALIZER)
#    define _STLP_MUTEX_INITIALIZER = { PTHREAD_MUTEX_INITIALIZER }
#   endif

//HPUX variants have (on some platforms optional) non-standard "DCE" pthreads impl
#   if defined(_DECTHREADS_) && (defined(_PTHREAD_USE_D4) || defined(__hpux)) && !defined(_CMA_SUPPRESS_EXTERNALS_)
#    define _STLP_PTHREAD_ATTR_DEFAULT pthread_mutexattr_default
#   else
#    define _STLP_PTHREAD_ATTR_DEFAULT 0
#   endif
#  endif // !_STLP_USE_PTHREAD_SPINLOCK 

# elif defined(_STLP_WIN32THREADS)
#  if !defined (_STLP_WINDOWS_H_INCLUDED) && ! defined (_WINDOWS_H)
#   if ! (defined ( _STLP_MSVC ) || defined (__BORLANDC__) || defined (__ICL) || defined (__WATCOMC__) || defined (__MINGW32__) || defined (__DMC__))
#    ifdef _STLP_USE_MFC
#     include <afx.h>
#    else
#     include <windows.h>
#    endif
#    define _STLP_WINDOWS_H_INCLUDED
#   else 
// This section serves as a replacement for windows.h header for Visual C++
extern "C" {
#   if (defined(_M_MRX000) || defined(_M_ALPHA) \
       || (defined(_M_PPC) && (_MSC_VER >= 1000))) && !defined(RC_INVOKED)
#    define InterlockedIncrement       _InterlockedIncrement
#    define InterlockedDecrement       _InterlockedDecrement
#    define InterlockedExchange        _InterlockedExchange
#    define _STLP_STDCALL
#   else
#    ifdef _MAC
#     define _STLP_STDCALL _cdecl
#    else
#     define _STLP_STDCALL __stdcall
#    endif
#   endif

#if (_MSC_VER >= 1300) || defined (_STLP_NEW_PLATFORM_SDK)
_STLP_IMPORT_DECLSPEC long _STLP_STDCALL InterlockedIncrement(long volatile *);
_STLP_IMPORT_DECLSPEC long _STLP_STDCALL InterlockedDecrement(long volatile *);
_STLP_IMPORT_DECLSPEC long _STLP_STDCALL InterlockedExchange(long volatile *, long);
#else
  // boris : for the latest SDK, you may actually need the other version of the declaration (above)
  // even for earlier VC++ versions. There is no way to tell SDK versions apart, sorry ...
_STLP_IMPORT_DECLSPEC long _STLP_STDCALL InterlockedIncrement(long*);
_STLP_IMPORT_DECLSPEC long _STLP_STDCALL InterlockedDecrement(long*);
_STLP_IMPORT_DECLSPEC long _STLP_STDCALL InterlockedExchange(long*, long);
#endif

_STLP_IMPORT_DECLSPEC void _STLP_STDCALL Sleep(unsigned long);
_STLP_IMPORT_DECLSPEC void _STLP_STDCALL OutputDebugStringA( const char* lpOutputString );

#ifdef _STLP_DEBUG
typedef unsigned long DWORD;
_STLP_IMPORT_DECLSPEC DWORD _STLP_STDCALL GetCurrentThreadId();
#endif /* _STLP_DEBUG */

#    if defined (InterlockedIncrement)
#     pragma intrinsic(_InterlockedIncrement)
#     pragma intrinsic(_InterlockedDecrement)
#     pragma intrinsic(_InterlockedExchange)
#    endif
} /* extern "C" */

#   endif /* STL_MSVC */

#   define _STLP_WINDOWS_H_INCLUDED

#  endif /* _STLP_WIN32 */

#  ifndef _STLP_ATOMIC_INCREMENT
#   define _STLP_ATOMIC_INCREMENT(__x)           InterlockedIncrement((long*)__x)
#   define _STLP_ATOMIC_DECREMENT(__x)           InterlockedDecrement((long*)__x)
#   define _STLP_ATOMIC_EXCHANGE(__x, __y)       InterlockedExchange((long*)__x, (long)__y)
#  endif
# elif defined(__DECC) || defined(__DECCXX)
#  include <machine/builtins.h>
#  define _STLP_ATOMIC_EXCHANGE __ATOMIC_EXCH_LONG
#  define _STLP_ATOMIC_INCREMENT(__x) __ATOMIC_ADD_LONG(__x, 1)
#  define _STLP_ATOMIC_DECREMENT(__x) __ATOMIC_ADD_LONG(__x, -1)
# elif defined(_STLP_SPARC_SOLARIS_THREADS)
#  include <stl/_sparc_atomic.h>
# elif defined (_STLP_UITHREADS)
// this inclusion is potential hazard to bring up all sorts
// of old-style headers. Let's assume vendor already know how
// to deal with that.
#  include <ctime>
# if defined (_STLP_USE_NAMESPACES) && ! defined (_STLP_VENDOR_GLOBAL_CSTD)
using _STLP_VENDOR_CSTD::time_t;
# endif
#  include <synch.h>
#  include <cstdio>
#  include <stl/_cwchar.h>
# elif defined (_STLP_BETHREADS)
#  include <OS.h>
#include <cassert>
#include <stdio.h>
#  define _STLP_MUTEX_INITIALIZER = { 0 }
#elif defined(_STLP_OS2THREADS)
# ifdef __GNUC__
#  define INCL_DOSSEMAPHORES
#  include <os2.h>
# else
  // This section serves to replace os2.h for VisualAge C++
  typedef unsigned long ULONG;
  #ifndef __HEV__  /* INCL_SEMAPHORE may also define HEV */
    #define __HEV__
    typedef ULONG HEV;
    typedef HEV*  PHEV;
  #endif
  typedef ULONG APIRET;
  typedef ULONG HMTX;
  typedef HMTX*  PHMTX;
  typedef const char*  PCSZ;
  typedef ULONG BOOL32;
  APIRET _System DosCreateMutexSem(PCSZ pszName, PHEV phev, ULONG flAttr, BOOL32 fState);
  APIRET _System DosRequestMutexSem(HMTX hmtx, ULONG ulTimeout);
  APIRET _System DosReleaseMutexSem(HMTX hmtx);
  APIRET _System DosCloseMutexSem(HMTX hmtx);
# define _STLP_MUTEX_INITIALIZER = { 0 };
#  endif /* GNUC */
# endif

# ifndef _STLP_MUTEX_INITIALIZER
#   if defined(_STLP_ATOMIC_EXCHANGE)
// we are using our own spinlock. 
#     define _STLP_MUTEX_INITIALIZER = { 0 }
#   elif defined(_STLP_UITHREADS)
// known case
#     define _STLP_MUTEX_INITIALIZER = { DEFAULTMUTEX }
#   else
// we do not have static initializer available. therefore, on-demand synchronization is needed.
#     define _STLP_MUTEX_INITIALIZER
#     define _STLP_MUTEX_NEEDS_ONDEMAND_INITIALIZATION
#   endif
# endif

_STLP_BEGIN_NAMESPACE

#ifndef _STLP_USE_PTHREAD_SPINLOCK
// Helper struct.  This is a workaround for various compilers that don't
// handle static variables in inline functions properly.
template <int __inst>
struct _STLP_mutex_spin {
  enum { __low_max = 30, __high_max = 1000 };
  // Low if we suspect uniprocessor, high for multiprocessor.
  static unsigned __max;
  static unsigned __last;
  static void _STLP_CALL _M_do_lock(volatile __stl_atomic_t* __lock);
  static void _STLP_CALL _S_nsec_sleep(int __log_nsec);
};
#endif // !_STLP_USE_PTHREAD_SPINLOCK


// Locking class.  Note that this class *does not have a constructor*.
// It must be initialized either statically, with _STLP_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.

// For non-static cases, clients should use  _STLP_mutex.

struct _STLP_CLASS_DECLSPEC _STLP_mutex_base
{
#if defined(_STLP_ATOMIC_EXCHANGE) || defined(_STLP_SGI_THREADS)
  // It should be relatively easy to get this to work on any modern Unix.
  volatile __stl_atomic_t _M_lock;
#endif

#ifdef _STLP_THREADS

# ifdef _STLP_ATOMIC_EXCHANGE
  inline void _M_initialize() { _M_lock=0; }
  inline void _M_destroy() {}

  void _M_acquire_lock() {
    _STLP_mutex_spin<0>::_M_do_lock(&_M_lock);
  }

  inline void _M_release_lock() {
    volatile __stl_atomic_t* __lock = &_M_lock;
#  if defined(_STLP_SGI_THREADS) && defined(__GNUC__) && __mips >= 3
        asm("sync");
        *__lock = 0;
#  elif defined(_STLP_SGI_THREADS) && __mips >= 3 \
	 && (defined (_ABIN32) || defined(_ABI64))
        __lock_release(__lock);
#  elif defined (_STLP_SPARC_SOLARIS_THREADS)
#   if defined (__WORD64) || defined (__arch64__) || defined (__sparcv9) || defined (__sparcv8plus)
	asm("membar #StoreStore ; membar #LoadStore");
#   else
	asm(" stbar ");
#   endif
        *__lock = 0;	
#  else
        *__lock = 0;
        // This is not sufficient on many multiprocessors, since
        // writes to protected variables and the lock may be reordered.
#  endif
  }
# elif defined(_STLP_PTHREADS)
#  ifdef _STLP_USE_PTHREAD_SPINLOCK
  pthread_spinlock_t _M_lock;
  inline void _M_initialize() { pthread_spin_init( &_M_lock, 0 ); }
  inline void _M_destroy() { pthread_spin_destroy( &_M_lock ); }

  inline void _M_acquire_lock() { 
    // we do not care about race conditions here : there is only one thread at this point 
    if(!_M_lock) pthread_spin_init( &_M_lock, 0 );

    // fbp: here, initialization on demand should happen before the lock
    // we use simple strategy as we are sure this only happens on initialization
    pthread_spin_lock( &_M_lock );