pthread_mutexattr_getrobust_np(3C)										pthread_mutexattr_getrobust_np(3C)

NAME

       pthread_mutexattr_getrobust_np, pthread_mutexattr_setrobust_np - get or set robustness attribute of mutex attribute object

SYNOPSIS

       cc -mt [ flag... ] file... -lpthread [ library... ]
       #include <pthread.h>

       int pthread_mutexattr_getrobust_np(const pthread_mutexattr_t *attr, int *robustness);

       int pthread_mutexattr_setrobust_np(pthread_mutexattr_t *attr, int robustness);

       The following applies only if the symbol _POSIX_THREAD_PRIO_INHERIT is defined, and the mutex attributes object attr should be used only to
       initialize mutexes that will also be initialized with the protocol attribute having  the  value	PTHREAD_PRIO_INHERIT.  See  pthread_mutex-
       attr_getprotocol(3C).

       The  pthread_mutexattr_setrobust_np()  and  pthread_mutexattr_getrobust_np()  functions	set  and  get  the robustness attribute of a mutex
       attribute object pointed to by attr that was previously created by the function pthread_mutexattr_init(3C).

       The robustness attribute defines the behavior when the owner of a mutex dies. The value of robustness may be ether  PTHREAD_MUTEX_ROBUST_NP
       or   PTHREAD_MUTEX_STALLED_NP,  which  are  defined  by	the  header  <pthread.h>.  The	default  value	of  the  robustness  attribute	is
       PTHREAD_MUTEX_STALLED_NP.

       When the owner of a mutex with the PTHREAD_MUTEX_STALLED_NP robustness attribute dies, all future calls to pthread_mutex_lock(3C) for  this
       mutex will be blocked from progress in an unspecified manner.

       When  the owner of a mutex with the PTHREAD_MUTEX_ROBUST_NP robustness attribute dies, the mutex is unlocked.  The next owner of this mutex
       acquires it with an error value of EOWNERDEAD. Note that the application must always check the return value from pthread_mutex_lock() for a
       mutex initialized with the PTHREAD_MUTEX_ROBUST_NP robustness  attribute. The new owner of this mutex should then attempt to make the state
       protected by the mutex consistent,  since this state could have been left inconsistent when the last owner died. If the new owner  is  able
       to make the state consistent, it should call pthread_mutex_consistent_np(3C) for the mutex and then unlock the mutex. If for any reason the
       new owner is not able to make the state consistent,  it should not call pthread_mutex_consistent_np() for  the  mutex,  but  should  simply
       unlock  the  mutex.  In	the  latter scenario, all waiters will be  awakened and all subsequent	calls to pthread_mutex_lock() will fail in
       acquiring the mutex with an error value of  ENOTRECOVERABLE. The mutex can then be made consistent by uninitializing  the  mutex  with  the
       pthread_mutex_destroy()	function  and  reinitializing it with the pthread_mutex_init() function. If the thread that acquired the lock with
       EOWNERDEAD dies, the next owner will acquire the lock with an error value of EOWNERDEAD.

       Note that the mutex may be in memory shared between processes or in memory private to a process, i.e. the "owner"  referenced  above  is  a
       thread, either within or outside the requestor's process.

       The mutex memory must be zeroed before initialization.

       Upon  successful  completion,  the  pthread_mutexattr_getrobust_np() and pthread_mutexattr_setrobust_np() functions return 0. Otherwise, an
       error number is returned to indicate the error.

       The pthread_mutexattr_getrobust_np() and pthread_mutexattr_setrobust_np() functions will fail if:

       EINVAL	       The value specified by attr or robustness is invalid.

       ENOSYS	       The option _POSIX_THREAD_PRIO_INHERIT is not defined and the implementation does not support the function.

       ENOTSUP	       The value specified by robustness is an unsupported value.

       See attributes(5)  for descriptions of the following attributes:

       +-----------------------------+-----------------------------+
       |      ATTRIBUTE TYPE	     |	    ATTRIBUTE VALUE	   |
       +-----------------------------+-----------------------------+
       |MT-Level		     | MT-Safe			   |
       +-----------------------------+-----------------------------+

       pthread_mutex_lock(3C), pthread_mutex_consistent_np(3C), pthread_mutexattr_getprotocol(3C), attributes(5), mutex(5), standards(5)

								    23 Mar 2005 				pthread_mutexattr_getrobust_np(3C)