pthread_mutexattr_setrobust()
Set the robust attribute in a mutex attribute object
Synopsis:
#include <pthread.h>
int pthread_mutexattr_setrobust( pthread_mutexattr_t *attr,
int robust );
Arguments:
- attr
- A pointer to the pthread_mutexattr_t object whose attribute you want to set.
- robust
- The value for the attribute; one of:
- PTHREAD_MUTEX_STALLED
- PTHREAD_MUTEX_ROBUST
For more information, see below.
Library:
libc
Use the -l c option to qcc to link against this library. This library is usually included automatically.
Description:
The pthread_mutexattr_setrobust() function sets the robust attribute in the mutex attribute object attr:
- 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 subsequent and in-progress attempts to lock the mutex will either fail with the error ENOTRECOVERABLE or will be left mutex-blocked. The only permissible operation on such a mutex is pthread_mutex_destroy().
You can use pthread_mutexattr_getrobust() to get the value of this attribute. The behavior of a mutex also depends on its type; see pthread_mutexattr_settype().
Returns:
- EOK
- Success.
- EINVAL
- The value specified by robust is invalid.
Classification:
| Safety: | |
|---|---|
| Cancellation point | No |
| Signal handler | Yes |
| Thread | Yes |