pthread_rwlock_timedrdlocStandard C Library Funcpthread_rwlock_timedrdlock(3C)NAME
pthread_rwlock_timedrdlock, pthread_rwlock_reltimedrdlock_np - lock a
read-write lock for reading
SYNOPSIS
cc -mt [ flag... ] file... [ library... ]
#include <pthread.h>
#include <time.h>
int pthread_rwlock_timedrdlock(pthread_rwlock_t *restrict rwlock, const
struct timespec *restrict abs_timeout);
int pthread_rwlock_reltimedrdlock_np(pthread_rwlock_t *restrict rwlock,
const struct timespec *restrict rel_timeout);
DESCRIPTION
The pthread_rwlock_timedrdlock() function applies a read lock to the
read-write lock referenced by rwlock as in the
pthread_rwlock_rdlock(3C) function. If the lock cannot be acquired
without waiting for other threads to unlock the lock, this wait will be
terminated when the specified timeout expires. The timeout expires when
the absolute time specified by abs_timeout passes, as measured by the
CLOCK_REALTIME clock (that is, when the value of that clock equals or
exceeds abs_timeout), or if the absolute time specified by abs_timeout
has already been passed at the time of the call.
The pthread_rwlock_reltimedrdlock_np() function is identical to the
pthread_rwlock_timedrdlock() function, except that the timeout is spec‐
ified as a relative time interval. The timeout expires when the time
interval specified by rel_timeout passes, as measured by the
CLOCK_REALTIME clock, or if the time interval specified by rel_timeout
is negative at the time of the call.
The resolution of the timeout is the resolution of the CLOCK_REALTIME
clock. The timespec data type is defined in the <time.h> header. Under
no circumstances does either function fail with a timeout if the lock
can be acquired immediately. The validity of the timeout parameter need
not be checked if the lock can be immediately acquired.
If a signal that causes a signal handler to be executed is delivered to
a thread blocked on a read-write lock with a call to
pthread_rwlock_timedrdlock() or pthread_rwlock_reltimedrdlock_np(),
upon return from the signal handler the thread resumes waiting for the
lock as if it was not interrupted.
The calling thread might deadlock if at the time the call is made it
holds a write lock on rwlock.
The results are undefined if this function is called with an uninitial‐
ized read-write lock.
RETURN VALUES
The pthread_rwlock_timedrdlock() and pthread_rwlock_reltimedrdlock_np()
functions return 0 if the lock for reading on the read-write lock
object referenced by rwlock is acquired. Otherwise, an error number is
returned to indicate the error.
ERRORS
The pthread_rwlock_timedrdlock() and and pthread_rwlock_reltimedrd‐
lock_np() functions will fail if:
ETIMEDOUT The lock could not be acquired before the specified
timeout expired.
The pthread_rwlock_timedrdlock() and pthread_rwlock_reltimedrdlock_np()
functions may fail if:
EAGAIN The read lock could not be acquired because the maximum
number of read locks for lock would be exceeded.
EDEADLK The calling thread already holds a write lock on
rwlock.
EINVAL The value specified by rwlock does not refer to an ini‐
tialized read-write lock object, or the timeout
nanosecond value is less than zero or greater than or
equal to 1 000 million.
ATTRIBUTES
See attributes(5) for descriptions of the following attributes:
┌─────────────────────────────┬─────────────────────────────┐
│ ATTRIBUTE TYPE │ ATTRIBUTE VALUE │
├─────────────────────────────┼─────────────────────────────┤
│Interface Stability │See below. │
├─────────────────────────────┼─────────────────────────────┤
│MT-Level │MT-Safe │
└─────────────────────────────┴─────────────────────────────┘
The pthread_rwlock_timedrdlock() function is Standard. The
pthread_rwlock_reltimedrdlock_np() is Stable.
SEE ALSOpthread_rwlock_destroy(3C), pthread_rwlock_rdlock(3C),
pthread_rwlock_timedwrlock(3C), pthread_rwlock_trywrlock(3C),
pthread_rwlock_unlock(3C), pthread_rwlock_wrlock(3C), attributes(5),
standards(5)SunOS 5.10 30 Jan 2004 pthread_rwlock_timedrdlock(3C)
