pthread_mutexattr_getrobuStandard)C Library 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);
DESCRIPTION
The pthread_mutexattr_setrobust_np() and pthread_mutexattr_getro‐
bust_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 could be either 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, or when the process containing such a locked mutex
unmaps the memory containing the mutex or performs one of the exec(2)
functions, the mutex is unlocked. The next owner of this mutex
acquires it with an error value of EOWNERDEAD. Note that the applica‐
tion 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_consis‐
tent_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 acquir‐
ing the mutex with an error value of ENOTRECOVERABLE. If the thread
that acquired the lock with EOWNERDEAD dies, the next owner will
acquire the lock with an error value of EOWNERDEAD.
The mutex memory must be zeroed before first initialization. Any thread
in any process interested in the robust lock can call
pthread_mutex_init(3C) to potentially initialize it, provided that all
such callers of pthread_mutex_init() specify the same set of attributes
in their attribute structures. In this situation, if
pthread_mutex_init() is called on a previously initialized robust
mutex, it will not reinitialize the mutex and will return the error
value EBUSY. If pthread_mutex_init() is called on a previously initial‐
ized robust mutex, and if the caller specifies a different set of
attributes from those already in effect for the mutex, it will not
reinitialize the mutex and will return the error value EINVAL.
RETURN VALUES
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.
ERRORS
The pthread_mutexattr_getrobust_np() and pthread_mutexattr_setro‐
bust_np() functions will fail if:
EINVAL The value specified by attr or robustness is invalid.
ATTRIBUTES
See attributes(5) for descriptions of the following attributes:
┌─────────────────────────────┬─────────────────────────────┐
│ ATTRIBUTE TYPE │ ATTRIBUTE VALUE │
├─────────────────────────────┼─────────────────────────────┤
│MT-Level │ MT-Safe │
└─────────────────────────────┴─────────────────────────────┘
SEE ALSOpthread_mutex_init(3C), pthread_mutex_lock(3C), pthread_mutex_consis‐
tent_np(3C), pthread_mutexattr_getpshared(3C), attributes(5), mutex(5),
standards(5)SunOS 5.10 5 Jun 2007pthread_mutexattr_getrobust_np(3C)
