pthread_rwlockattr_getclock()
Get the clock attribute from a read-write lock attribute object
Synopsis:
#include <pthread.h>
int pthread_rwlockattr_getclock(
const pthread_rwlockattr_t *attr,
clockid_t *id );
Arguments:
- attr
- A pointer to the pthread_rwlockattr_t object from which you want to get the clock.
- id
- A pointer to a clockid_t object where the function can store the clock ID.
Library:
libc
Use the -l c option to qcc to link against this library. This library is usually included automatically.
Description:
The pthread_rwlockattr_getclock() function obtains the value of the clock attribute from the attributes object referenced by attr.
The clock attribute is the clock ID of the clock that's used (as a QNX Neutrino extension) to measure the timeout service of pthread_rwlock_timedrdlock() or pthread_rwlock_timedwrlock(); one of:
- CLOCK_REALTIME — the standard POSIX-defined clock. Timers based on this clock wake up the processor if it's in a power-saving mode.
- CLOCK_SOFTTIME — (a QNX Neutrino extension)
this clock is active only when
the processor isn't in a power-saving mode.
For example, an application using a CLOCK_SOFTTIME timer
to sleep wouldn't wake up
the processor when the application was due to wake up.
This will allow the processor to enter a power-saving mode.
While the processor isn't in a power-saving mode, CLOCK_SOFTTIME behaves the same as CLOCK_REALTIME.
- CLOCK_MONOTONIC — this clock always increases at a constant rate and can't be adjusted.
The default value of the clock attribute is CLOCK_REALTIME.
For more information about the different clocks, see
Other clock sources
in the Clocks, Timers, and Getting a Kick Every So Often chapter of
Getting Started with QNX Neutrino.
Returns:
- EOK
- Success.
Classification:
| Safety: | |
|---|---|
| Cancellation point | No |
| Interrupt handler | No |
| Signal handler | Yes |
| Thread | Yes |