锁的实现

class OSMutex
{
public:

    OSMutex();
    ~OSMutex();

    inline void Lock();
    inline void Unlock();

    // Returns true on successful grab of the lock, false on failure
    inline Bool16 TryLock();

private:

#ifdef __Win32__
    CRITICAL_SECTION fMutex;

    DWORD       fHolder;
    UInt32      fHolderCount;

#elif !__PTHREADS_MUTEXES__
    mymutex_t fMutex;
#else
    pthread_mutex_t fMutex;
    // These two platforms don't implement pthreads recursive mutexes, so
    // we have to do it manually
    pthread_t   fHolder;
    UInt32      fHolderCount;
#endif

#if __PTHREADS_MUTEXES__ || __Win32__       
    void        RecursiveLock();
    void        RecursiveUnlock();
    Bool16      RecursiveTryLock();
#endif
    friend class OSCond;
};

class OSMutexLocker
{
public:

    OSMutexLocker(OSMutex* inMutexP) : fMutex(inMutexP) { if (fMutex != NULL) fMutex->Lock(); }
    ~OSMutexLocker() { if (fMutex != NULL) fMutex->Unlock(); }

    void Lock() { if (fMutex != NULL) fMutex->Lock(); }
    void Unlock() { if (fMutex != NULL) fMutex->Unlock(); }

private:
    OSMutex*    fMutex;

};

OSMutexLocker 通过构造函数和析构函数完成对区块的上锁和解锁，当需要对部分进行锁定时：

fun()

{

      operation........

        {

              OSMutexLocker  locker(...)

       }

     opearation.....

}