Tribblix: manual page: pthread_mutexattr

PTHREAD_MUTEXATTR_GETROBUST(3C) Standard C Library Functions

NAME

pthread_mutexattr_getrobust, pthread_mutexattr_setrobust - get and set
the mutex robust attribute

SYNOPSIS

#include <pthread.h>

int
pthread_mutexattr_getrobust(const pthread_mutexattr_t *attr,
int *robust);

int
pthread_mutexattr_setrobust(pthread_mutexattr_t *attr, int robust);

DESCRIPTION

The pthread_mutexattr_getrobust() and pthread_mutexattr_setrobust()
functions obtain and set a mutex's robust attribute, putting it in, or
obtaining it from robust. The valid values for robust include:

PTHREAD_MUTEX_STALLED
The mutex referred to by attr is a traditional mutex.
When a thread holding an intra-process lock or a process
holding an inter-process lock crashes or terminates
without unlocking the mutex, then the lock will be
stalled. For another thread or process to obtain the
lock, something else must unlock it.

PTHREAD_MUTEX_ROBUST
The mutex referred to by attr is considered a robust
mutex. When a process holding an inter-process lock
crashes or terminates without unlocking the mutex, the
attempt to lock it will return EOWNERDEAD. This allows
the new owner the chance to fix the internal state and
call pthread_mutex_consistent(3C) prior to unlocking the
lock, allowing normal operation to proceed. Any crashes
while in this state cause the next owner to obtain
EOWNERDEAD.

RETURN VALUES

Upon successful completion, the pthread_mutexattr_getrobust() function
will return 0 and update robust with the current value of the robust
attribute. Upon successful completion, the
pthread_mutexattr_setrobust() function will return 0 and update the
robust property of the attributes pointed to by attr to robust. If
either function fails, an error code will be returned to indicate the
error. Valid errors are defined below.

ERRORS

The pthread_mutexattr_getrobust() function will fail if:

EINVAL attr is invalid or a null pointer, robust is a null
pointer.

The pthread_mutexattr_setrobust() function will fail if:

EINVAL attr is invalid or a null pointer, robust is not one
of PTHREAD_MUTEX_STALLED or PTHREAD_MUTEX_ROBUST.

INTERFACE STABILITY