Commit 18c61189 authored by msvensson@pilot.mysql.com's avatar msvensson@pilot.mysql.com
Browse files

Bug#30992 Wrong implementation of pthread_mutex_trylock() 

It's not possible to use WaitForSingleObject to wait
on a CRITICAL_SECTION, instead use the TryEnterCriticalSection function.
 - if "mutex" was already taken => return EBUSY
 - if "mutex" was aquired => return 0
parent 23622616

include/config-win.h

+3 −0
Original line number Diff line number Diff line
@@ -19,6 +19,9 @@ 
/* We have to do this define before including windows.h to get the AWE API

functions */

#define _WIN32_WINNT     0x0500

#else

/* Get NT 4.0 functions */

#define _WIN32_WINNT     0x0400

#endif



#if defined(_MSC_VER) && _MSC_VER >= 1400

mysys/my_winthread.c

+10 −12
Original line number Diff line number Diff line
@@ -40,31 +40,29 @@ void win_pthread_init(void) 
  pthread_mutex_init(&THR_LOCK_thread,MY_MUTEX_INIT_FAST);

}





/**

   Adapter to @c pthread_mutex_trylock()



   @retval 0      Mutex was acquired

   @retval EBUSY  Mutex was already locked by a thread

   @retval EINVAL Mutex could not be acquired due to other error

 */

int

win_pthread_mutex_trylock(pthread_mutex_t *mutex)

{

  switch (WaitForSingleObject(mutex, 0)) {

  case WAIT_TIMEOUT:

  if (TryEnterCriticalSection(mutex))

  {

    /* Don't allow recursive lock */

    if (mutex->RecursionCount > 1){

      LeaveCriticalSection(mutex);

      return EBUSY;



  default:

  case WAIT_FAILURE:

    return EINVAL;



  case WAIT_OBJECT_0:

  case WAIT_ABANDONED: /* The mutex was acquired because it was

                        * abandoned */

    }

    return 0;

  }

  return EBUSY;

}





/*

** We have tried to use '_beginthreadex' instead of '_beginthread' here

** but in this case the program leaks about 512 characters for each