Re: critical section

["Scott McCaskill" <scott@magruder.org>]

It looks like you're trying to make a non-recursive mutex (can only be
locked once by any thread, including the mutex owner).  pthread_mutex can
already do this; is there some reason you're not using it this way directly?
See pthread_mutexattr_settype().

----- Original Message -----
From: "Ye Liu" <yliu@tibco.com>
To: "win32-pthread" <pthreads-win32@sourceware.cygnus.com>
Sent: Tuesday, July 31, 2001 4:27 PM
Subject: critical section


> 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
>
>
>