pthread_mutex_init Subroutine



Purpose

Initializes a mutex and sets its attributes.

Library

Threads Library (libpthreads.a)

Syntax

#include <pthread.h>

int pthread_mutex_init (mutex, attr)
pthread_mutex_t *mutex;
pthread_mutexattr_t *attr;

Description

The pthread_mutex_init subroutine initializes a new mutex mutex, and
sets its attributes according the mutex attributes object attr. The
mutex is initially unlocked.

After initialization of the mutex, the mutex attributes object can
be reused for another mutex initialization, or deleted.

Note:	The pthread.h header file must be the first included file of
each source file using the threads library.

Parameters

mutex	Specifies the mutex to be created.

attr	Specifes the mutex attributes object to use for initializing
the mutex. If the value is NULL, the default attributes values are
used.

Return Values

Upon successful completion, the new mutex is returned via the mutex
parameter, and 0 is returned. Otherwise, an error code is returned.

Error Codes

The pthread_mutex_init subroutine is unsuccessful if the following
is true:

EAGAIN	The system does not have sufficient resources, other than memory,
to initialize a new mutex.

EBUSY	The mutex mutex is already in use: it was previously created
with by calling the pthread_mutex_init subroutine, and not destroyed
by calling the pthread_mutex_destroy subroutine.

EINVAL	The mutex or attr parameters are not valid.

ENOMEM	There is not sufficient memory to initialize a new mutex.

Implementation Specifics

This subroutine is part of the Base Operating System (BOS) Runtime.

Related Information

The pthread_mutexattr_init subroutine, pthread_mutexattr_destroy subroutine,
pthread_mutex_lock or pthread_mutex_trylock subroutine, pthread_mutex_destroy
subroutine, PTHREAD_MUTEX_INITIALIZER macro.

Using Mutexes.

Threads Library Quick Reference.