hxmutexlock.h

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                        : "0" (pLock), "1" (1));
    return nOldBit;
}

/***********************************************************************
 * Solaris / sparc / native compiler
 *
 * Implementation Notes:
 *   Uses assembly mutex
 *   native-compiler syntax
 */
#elif defined _SOLARIS /* native compiler */

extern "C" int _HXMutexSetBitCAS(HX_MUTEX pLock);
extern "C" int _HXMutexSetBitSWAP(HX_MUTEX pLock);
extern "C" int _HXMutexClearBit(HX_MUTEX pLock);

#define _HXMutexSetBit(pLock)      _HXMutexSetBitCAS(pLock)
#define _HXMutexYieldCPUIfNeeded() /* not needed */
#define _HXMutexInitBit(pLock)     _HXMutexClearBit(pLock)
#define _HXMutexDestroyBit(pLock)  /* not needed */


/***********************************************************************
 * IRIX / MIPS
 *
 * Implementation Notes:
 *   Uses native mutex calls acquire_lock/etc.
 *   On this platform we explicitly yield the processor
 */
#elif defined _IRIX

#define _HXMutexYieldCPUIfNeeded() sginap(0)
#define _HXMutexSetBit(pLock)      acquire_lock(pLock)
#define _HXMutexClearBit(pLock)    release_lock(pLock)
#define _HXMutexInitBit(pLock)     init_lock(pLock)
#define _HXMutexDestroyBit(pLock)  /* not needed */


/***********************************************************************
 * AIX / PowerPC
 *
 * Implementation Notes:
 *   Uses native mutex calls msem_lock/etc.
 */
#elif defined _AIX

// NATIVE MUTEX
//this doesn't work cleanly, we had to customize HXMutexLock() for AIX
#define _HXMutexYieldCPUIfNeeded() /* not needed */
#define _HXMutexSetBit(pLock)      msem_lock(pLock, MSEM_IF_NOWAIT)
#define _HXMutexClearBit(pLock)    msem_unlock(pLock, 0)
#define _HXMutexInitBit(pLock)     msem_init(pLock, MSEM_UNLOCKED)
#define _HXMutexDestroyBit(pLock)  msem_remove(pLock)

// ASSEMBLY MUTEX
//#include <sched.h>
//#define _HXMutexYieldCPUIfNeeded() sched_yield()
//extern "C" int _HXMutexSetBit(HX_MUTEX pLock);
//extern "C" int _HXMutexClearBit(HX_MUTEX pLock);
//#define _HXMutexInitBit(pLock)     _HXMutexClearBit(pLock)
//#define _HXMutexDestroyBit(pLock)  /* not needed */


/***********************************************************************
 * HP-UX / Itanium
 *
 * Implementation Notes:
 *   Uses non-inline assembly mutex call _HXMutexSetBit(), defined
 *   in common/util/platform/hpux/spinlock-ia64.s.   XXX: make this inline.
 */
#elif defined _HPUX && defined _IA64

extern "C" int _HXMutexSetBit(HX_MUTEX pLock);
extern "C" int _HXMutexClearBit(HX_MUTEX pLock);

#define _HXMutexYieldCPUIfNeeded() /* not needed */
#define _HXMutexInitBit(pLock)     _HXMutexClearBit(pLock)
#define _HXMutexDestroyBit(pLock)  /* not needed */


/***********************************************************************
 * HP-UX / PA-RISC
 *
 * Implementation Notes:
 *   Uses non-inline assembly mutex call load_and_clear(), defined
 *   in common/util/platform/hpux/spin.s.   XXX: make this inline.
 *   The logic of this mutex is backwards from most of our others,
 *   1 means clear, 0 means set.
 */
#elif defined _HPUX

#define _HXMutexYieldCPUIfNeeded() /* not needed */
#define _HXMutexSetBit(pLock)      (load_and_clear((char* volatile)pLock) == 0)
#define _HXMutexClearBit(pLock)   release_spinlock(pLock)
#define _HXMutexInitBit(pLock)     _HXMutexClearBit(pLock)
#define _HXMutexDestroyBit(pLock)  /* not needed */

/***********************************************************************
 * Tru64 (OSF/1) / Alpha
 *
 * Implementation Notes:
 *   Uses native mutex calls __LOCK_LONG_RETRY/etc.
 *
 * TODO:
 *   This native mutex is much slower than on other platforms.
 *   Change this to use assembly.
 */
#elif defined _OSF1
#define _HXMutexYieldCPUIfNeeded() /* not needed */
#define _HXMutexSetBit(pLock)      (__LOCK_LONG_RETRY(pLock, 1) == 0)
#define _HXMutexClearBit(pLock)    __UNLOCK_LONG(pLock)
#define _HXMutexInitBit(pLock)     _HXMutexClearBit(pLock)
#define _HXMutexDestroyBit(pLock)  /* not needed */


/***********************************************************************
 * Misc. Unix / x86  (Linux, FreeBSD...)
 *
 * Implementation Notes:
 *   Uses assembly mutex
 *   GCC inline-assembly syntax
 *
 * TODO: add non-x86 support for Linux/FreeBSD/etc.
 */
#else

#define _HXMutexYieldCPUIfNeeded() /* not needed */
#define _HXMutexInitBit(pLock)     _HXMutexClearBit(pLock)
#define _HXMutexDestroyBit(pLock)  /* not needed */
#define _HXMutexClearBit(pLock)    (*(pLock) = 0)

/*
 * GCC gets really mad if we use eax / ebx in the assembly below.
 * We use ecx / edx instead (cross your fingers =)
 */
inline static int
_HXMutexSetBit(HX_MUTEX pLock)
{
    volatile int nOldBit;
    __asm__ __volatile__("xchg	%%ecx, (%%edx)"
			: "=c" (nOldBit)
			: "c" (1), "d" (pLock));
    return nOldBit;
}

#endif


/***********************************************************************
 * Common code, shared by multiple platforms
 *
 */

#if !defined(HELIX_FEATURE_SERVER) && !defined(HX_MUTEX_PRIVATE_COLLISION_COUNTERS) && !defined(HX_MUTEX_PRIVATE_COLLISION_COUNTERS)
//default for non-server products is to not use the collision counters
#define HX_MUTEX_NO_COLLISION_COUNTERS
#endif
#if defined HX_MUTEX_NO_COLLISION_COUNTERS
#define HXMutexCollision(p)    /* nothing */
#elif defined HX_MUTEX_PRIVATE_COLLISION_COUNTERS
/* User must define their own HXMutexCollision(p) */
#else
extern HX_MUTEX g_pServerMainLock;
extern UINT32* g_pConcurrentOps;
extern UINT32* g_pConcurrentMemOps;

inline void
HXMutexCollision(HX_MUTEX pLock)
{
    ++(*g_pConcurrentOps);
    if (pLock != g_pServerMainLock)
        ++(*g_pConcurrentMemOps);
}
#endif

#ifndef HX_MUTEX_CUSTOM_COLLISION_DELAY
#define HXMutexCollisionDelay(n) microsleep(n)
#else
/* User must define their own HXMutexCollisionDelay() */
#endif

//will obsolete these old names shortly...
#define HXCreateMutex()   HXMutexCreate()
#define HXInitMutex(p)    HXMutexInit(p)
#define HXUnInitMutex(p)  HXMutexUnInit(p)
#define HXDestroyMutex(p) HXMutexDestroy(p)

#ifdef HX_MUTEX_USE_MANAGED_LOCKS
HX_RESULT AddManagedMutex(HX_MUTEX pMutex);
HX_RESULT RemoveManagedMutex(HX_MUTEX pMutex);
#endif

inline void
HXMutexLock(HX_MUTEX pLock, BOOL bWait = FALSE)
{
#ifdef XXXDC_USE_BACKOFF
    if (_HXMutexSetBit(pLock))
    {
        register int nInitialTries = 1;
 	register int nDelay = BACKOFF_START;
   
        //spin on reads for a bit (not writes)
        while (*pLock && nInitialTries < BACKOFF_THRESHOLD)
        {
            HXMutexCollision(pLock);
            ++nInitialTries;
        }
        while(_HXMutexSetBit(pLock))
        {
            _HXMutexYieldCPUIfNeeded();
            if (bWait)
            {
		HXMutexCollisionDelay(nDelay);
		nDelay = nDelay * BACKOFF_FACTOR;
		if (nDelay > BACKOFF_MAX)
		    nDelay = BACKOFF_MAX;
            }
            HXMutexCollision(pLock);
        }
    }
#elif defined _AIX
    do
    {
        if (msem_lock(pLock, 0) == 0) break;
    } while (errno == EINTR);
#else
    while(_HXMutexSetBit(pLock))
    {
        _HXMutexYieldCPUIfNeeded();
        if (bWait)
        {
            HXMutexCollisionDelay(HX_MUTEX_DELAY);
        }
        HXMutexCollision(pLock);
    }
#endif

#ifdef HX_MUTEX_USE_MANAGED_LOCKS
    AddManagedMutex(pLock);
#endif

}

inline BOOL
HXMutexTryLock(HX_MUTEX pLock)
{
#ifdef _AIX
    BOOL bRet = (msem_lock(pLock, 0) == 0);
#ifdef HX_MUTEX_USE_MANAGED_LOCKS
    if (bRet)
        AddManagedMutex(pLock);
#endif
    return bRet;
#else
    if (_HXMutexSetBit(pLock))
    {
        HXMutexCollision(pLock);
        return FALSE;
    }
#ifdef HX_MUTEX_USE_MANAGED_LOCKS
    AddManagedMutex(pLock);
#endif
    return TRUE;
#endif
}

inline void
HXMutexUnlock(HX_MUTEX pLock)
{
#ifdef HX_MUTEX_USE_MANAGED_LOCKS
    RemoveManagedMutex(pLock);
#endif
    _HXMutexClearBit(pLock);
}

inline HX_MUTEX
HXMutexCreate()
{
    HX_MUTEX pLock = (HX_MUTEX) new HX_MUTEX_BASE_TYPE;
    _HXMutexInitBit(pLock);
    return pLock;
}

inline void
HXMutexInit(HX_MUTEX pLock)
{
    _HXMutexClearBit(pLock);
}

inline void
HXMutexUnInit(HX_MUTEX pLock)
{
   /* no-op */
}

inline void
HXMutexDestroy(HX_MUTEX pLock)
{
    _HXMutexDestroyBit(pLock);
#if defined _WINDOWS
    delete (void*)pLock;
#else
    delete pLock;
#endif
}

#endif /* _HXMUTEXLOCK_H_ */