Multithreaded Programming Guide

Making a Mutex Consistent

If the owner of a robust mutex terminates without unlocking the mutex, the mutex is unlocked and marked inconsistent. The next owner acquires the lock with an EOWNERDEAD return code.

pthread_mutex_consistent_np() makes the mutex object, mutex, consistent after the death of its owner.

pthread_mutex_consistent_np Syntax

#include <pthread.h> 
int pthread_mutex_consistent_np(pthread_mutex_t *mutex); 

Call pthread_mutex_lock() to acquire the inconsistent mutex. The EOWNWERDEAD return value indicates an inconsistent mutex.

Call pthread_mutex_consistent_np() while holding the mutex acquired by a previous call to pthread_mutex_lock().

The critical section protected by the mutex might have been left in an inconsistent state by a failed owner. In this case, make the mutex consistent only if you can make the critical section protected by the mutex consistent.

Calls to pthread_mutex_lock(), pthread_mutex_unlock() , and pthread_mutex_trylock() for a consistent mutex behave in the normal manner.

The behavior of pthread_mutex_consistent_np() for a mutex that is not inconsistent, or is not held, is undefined.

pthread_mutex_consistent_np Return Values

pthread_mutex_consistent_np() returns zero after completing successfully. Any other return value indicates that an error occurred.

pthread_mutex_consistent_np() fails if the following condition occurs:



The current thread does not own the mutex or the mutex is not a PTHREAD_MUTEX_ROBUST_NP mutex having an inconsistent state.