critical section

["Ye Liu" <yliu@tibco.com>]

Greets,

When I impelement the critical section using mutex, I have the following
code:

/*    TIBMutex.h    */
#ifndef _TIBMutex_H_
#define _TIBMutex_H_
class TIBMutex
{
public:
    TIBMutex();
     ~TIBMutex();
     void acquire();
     void acquire_yield();
     void release();
     int tryacquire();

private:
    pthread_mutex_t m_Mutex;
    pthread_mutexattr_t m_MutexAttr;
    void init_MutexAttr();
    int m_Count;
};

/*    TIBMutex.cpp    */
TIBMutex::TIBMutex()
{
 m_Count = 0;
 if  (pthread_mutex_init(&m_Mutex, &m_MutexAttr))
    /* error handling...*/
}

inline void TIBMutex::acquire()
{
 while (m_Count);

 if (pthread_mutex_lock(&m_Mutex))
 {
     /* error handling...*/
 }
 ++m_Count;
 return;
}

inline void TIBMutex::release()
{
 if (pthread_mutex_unlock(&m_Mutex))
 {
    /* error handling...*/
 }
 --m_Count;
}

My questions are:

1. Do I need use a condition variable here because I use m_Count as 0/1
signal?

2. In the acquire(), when m_Count is not 0, the waiting thread should
"spin" there as the above or yield like the following acquire_yield()

inline void TIBMutex::acquire_yield()
{
 while (m_Count)
  shed_yield();
 if (pthread_mutex_lock(&m_Mutex))
 {
    /* error handling...*/
 }
 ++m_Count;
 return;
}


--
Ye Liu
Tel(O) 650-846-5228