pthread_mutexattr_getrobust()

Get the robust attribute from a mutex attribute object

Synopsis:

#include <pthread.h>

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

Arguments:

attr: A pointer to the pthread_mutexattr_t object that you want to get the attribute from.
robust: A pointer to a location where the function can store the robust attribute.

Library:

libc

Use the -l c option to qcc to link against this library. This library is usually included automatically.

Description:

The pthread_mutexattr_getrobust() function gets the robust attribute from the mutex attribute object attr and stores it in robust. You can use pthread_mutexattr_setrobust() to set this attribute.

The valid values for the robust attribute are:

PTHREAD_MUTEX_STALLED

No special actions are taken if the owner of the mutex is terminated while holding the mutex lock. This can lead to deadlocks if no other thread can unlock the mutex. This is the default value.

PTHREAD_MUTEX_ROBUST

If the process containing the owning thread of a robust mutex terminates while holding the mutex lock, the next thread that acquires the mutex is notified about the termination by the return value EOWNERDEAD from the locking function.

The notified thread can then attempt to mark the state protected by the mutex as consistent again by a call to pthread_mutex_consistent(). After a subsequent successful call to pthread_mutex_unlock(), the mutex lock is released and can be used normally by other threads.

If the mutex is unlocked without a call to pthread_mutex_consistent(), it remains in a permanently unusable state and all attempts to lock the mutex fail with the error ENOTRECOVERABLE. The only permissible operation on such a mutex is pthread_mutex_destroy().

Returns:

EOK: Success.

Classification:

POSIX 1003.1

Safety:
Cancellation point	No
Interrupt handler	No
Signal handler	Yes
Thread	Yes