HP-UX Reference (11i v2 07/12) - 3 Library Functions N-Z (vol 7)

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pthread_mutexattr_init(3T) pthread_mutexattr_init(3T)

(Pthread Library)

NAME

pthread_mutexattr_init(), pthread_mutexattr_destroy() - initialize or destroy a mutex attributes object

SYNOPSIS

#include <pthread.h>

int pthread_mutexattr_init(

pthread_mutexattr_t *attr

);

int pthread_mutexattr_destroy(

pthread_mutexattr_t *attr

);

PARAMETERS

attr Pointer to the mutex attributes object to be initialized or destroyed.

DESCRIPTION

pthread_mutexattr_init()

initializes the mutex attributes object attr with the default values for

all attributes. The attributes object describes a mutex in detail and is passed to the mutex initialization

function.

When a mutex attributes object is used to initialize a mutex, the values of the individual attributes deter-

mine the characteristics of the new mutex. Attributes objects act like additional parameters to object ini-

tialization. A single attributes object can be used in multiple calls to the function

pthread_mutex_init()

When a mutex is initialized with an attributes object, the attributes are, in effect, copied into the mutex.

Consequently, any change to the attributes object will not affect any previously initialized mutexes. Once

all mutexes needing a speciﬁc attributes object have been initialized, the attributes object is no longer

needed.

The mutex attributes and their default values are:

process-shared The default value is

PTHREAD_PROCESS_PRIVATE.

type The default value is PTHREAD_MUTEX_DEFAULT

If an initialized mutex attributes object is reinitialized, undeﬁned behavior results.

pthread_mutexattr_destroy()

destroys the mutex attributes object attr. The destroyed mutex

attributes object ceases to exist and its resources are reclaimed. Using attr after it has been destroyed

results in undeﬁned behavior. A destroyed mutex attributes object can be reinitialized using the

pthread_mutexattr_init()

function.

Mutexes that have been already initialized using this attributes object are not affected by the destruction of

the mutex attributes object.

RETURN VALUE

Upon successful completion,

pthread_mutexattr_init()

and

pthread_mutexattr_destroy() return zero. Otherwise, an error number is returned to indicate

the error (the

errno variable is not set).

ERRORS

For each of the following conditions, if the condition is detected, the pthread_mutexattr_init()

and pthread_mutexattr_destroy() functions return the corresponding error number:

[ENOMEM] There is insufﬁcient memory available in which to initialize attr.

[EINVAL] The value speciﬁed by attr is invalid.

AUTHOR

pthread_mutexattr_init() and pthread_mutexattr_destroy()

were derived from the

IEEE POSIX P1003.1c standard.