The Open Group Base Specifications Issue 7
IEEE Std 1003.1-2008, 2016 Edition
Copyright © 2001-2016 The IEEE and The Open Group

#### NAME

> pthread_condattr_getclock, pthread_condattr_setclock - get and set the clock selection condition variable attribute

#### SYNOPSIS

> ``#include <pthread.h>
> int pthread_condattr_getclock(const pthread_condattr_t *restrict` attr`,
> clockid_t *restrict` clock_id`);
> int pthread_condattr_setclock(pthread_condattr_t *`attr`,
> clockid_t` clock_id`);
> ``

#### DESCRIPTION

> The pthread_condattr_getclock() function shall obtain the value of the clock attribute from the attributes object referenced by attr.

> The pthread_condattr_setclock() function shall set the clock attribute in an initialized attributes object referenced by attr. If pthread_condattr_setclock() is called with a clock_id argument that refers to a CPU-time clock, the call shall fail.

> The clock attribute is the clock ID of the clock that shall be used to measure the timeout service of pthread_cond_timedwait(). The default value of the clock attribute shall refer to the system clock.

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

#### RETURN VALUE

> If successful, the pthread_condattr_getclock() function shall return zero and store the value of the clock attribute of attr into the object referenced by the clock_id argument. Otherwise, an error number shall be returned to indicate the error.

> If successful, the pthread_condattr_setclock() function shall return zero; otherwise, an error number shall be returned to indicate the error.

#### ERRORS

> The pthread_condattr_setclock() function may fail if:

> [EINVAL]
>   The value specified by clock_id does not refer to a known clock, or is a CPU-time clock.

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

The following sections are informative.

#### EXAMPLES

> None.

#### APPLICATION USAGE

> None.

#### RATIONALE

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

#### FUTURE DIRECTIONS

> None.

#### SEE ALSO

> pthread_cond_destroy, pthread_cond_timedwait, pthread_condattr_destroy, pthread_condattr_getpshared, pthread_create, pthread_mutex_destroy

> XBD <pthread.h>

#### CHANGE HISTORY

> First released in Issue 6. Derived from IEEE Std 1003.1j-2000.

#### Issue 7

> The pthread_condattr_getclock() and pthread_condattr_setclock() functions are moved from the Clock Selection option to the Base.

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

End of informative text.

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