illumos: manual page: pthread_rwlock

PTHREAD_RWLOCK_TIMEDWRLOCK(3C) Standard C Library Functions

NAME

pthread_rwlock_timedwrlock, pthread_rwlock_reltimedwrlock_np - lock a
read-write lock for writing

SYNOPSIS

cc -mt [ flag... ] file... [ library... ]
#include <pthread.h>
#include <time.h>

int pthread_rwlock_timedwrlock(pthread_rwlock_t *restrict rwlock,
const struct timespec *restrict abs_timeout);

int pthread_rwlock_reltimedwrlock_np(pthread_rwlock_t *restrict rwlock,
const struct timespec *restrict rel_timeout);

DESCRIPTION

The pthread_rwlock_timedwrlock() function applies a write lock to the
read-write lock referenced by rwlock as in the pthread_rwlock_wrlock(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_reltimedwrlock_np() function is identical to the
pthread_rwlock_timedwrlock() function, except that the timeout is
specified 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 abs_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_timedwrlock() or pthread_rwlock_reltimedwrlock_np(), upon
return from the signal handler the thread resumes waiting for the lock as
if it was not interrupted.

The calling thread can deadlock if at the time the call is made it holds
the read-write lock. The results are undefined if this function is called
with an uninitialized read-write lock.

RETURN VALUES

The pthread_rwlock_timedwrlock() and pthread_rwlock_reltimedwrlock_np()
functions return 0 if the lock for writing 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_timedwrlock() and pthread_rwlock_reltimedwrlock_np()
functions will fail if:

ETIMEDOUT
The lock could not be acquired before the specified timeout
expired.

The pthread_rwlock_timedwrlock() and pthread_rwlock_reltimedwrlock_np()
functions may fail if:

EDEADLK
The calling thread already holds the rwlock.

EINVAL
The value specified by rwlock does not refer to an initialized
read-write lock object, or the timeout nanosecond value is
less than zero or greater than or equal to 1,000 million.

ATTRIBUTES