NAME

pthread_condattr_destroy, pthread_condattr_init — destroy and initialize the condition variable attributes object

SYNOPSIS

#include <pthread.h>

int pthread_condattr_destroy(pthread_condattr_t *attr);
int pthread_condattr_init(pthread_condattr_t *attr);


DESCRIPTION

The pthread_condattr_destroy() function shall destroy a condition variable attributes object; the object becomes, in effect, uninitialized. An implementation may cause pthread_condattr_destroy() to set the object referenced by attr to an invalid value. A destroyed attr attributes object can be reinitialized using pthread_condattr_init(); the results of otherwise referencing the object after it has been destroyed are undefined.

The pthread_condattr_init() function shall initialize a condition variable attributes object attr with the default value for all of the attributes defined by the implementation.

Results are undefined if pthread_condattr_init() is called specifying an already initialized attr attributes object.

After a condition variable attributes object has been used to initialize one or more condition variables, any function affecting the attributes object (including destruction) shall not affect any previously initialized condition variables.

This volume of POSIX.1-2024 requires two attributes, the clock attribute and the process-shared attribute.

Additional attributes, their default values, and the names of the associated functions to get and set those attribute values are implementation-defined.

The behavior is undefined if the value specified by the attr argument to pthread_condattr_destroy() does not refer to an initialized condition variable attributes object.

RETURN VALUE

If successful, the pthread_condattr_destroy() and pthread_condattr_init() functions shall return zero; otherwise, an error number shall be returned to indicate the error.

ERRORS

The pthread_condattr_init() function shall fail if:

[ENOMEM]

Insufficient memory exists to initialize the condition variable attributes object.

These functions shall not return an error code of [EINTR].

EXAMPLES

None.

APPLICATION USAGE

None.

RATIONALE

A process-shared attribute has been defined for condition variables for the same reason it has been defined for mutexes.

If an implementation detects that the value specified by the attr argument to pthread_condattr_destroy() does not refer to an initialized condition variable attributes object, it is recommended that the function should fail and report an [EINVAL] error.

See also pthread_attr_destroy and pthread_mutex_destroy.

FUTURE DIRECTIONS

None.

SEE ALSO

pthread_attr_destroy, pthread_cond_destroy, pthread_condattr_getpshared, pthread_create, pthread_mutex_destroy

XBD <pthread.h>

CHANGE HISTORY

First released in Issue 5. Included for alignment with the POSIX Threads Extension.

Issue 6

The pthread_condattr_destroy() and pthread_condattr_init() functions are marked as part of the Threads option.

Issue 7

The pthread_condattr_destroy() and pthread_condattr_init() functions are moved from the Threads option to the Base.

The [EINVAL] error for an uninitialized condition variable attributes object is removed; this condition results in undefined behavior.