pthread_rwlock_wrlock.3t (2010 09)

ManualsBrandsHP ManualsSoftwareHP-UX Manpages

pthread_rwlock_wrlock(3T) pthread_rwlock_wrlock(3T)

(Pthread Library)

NAME

pthread_rwlock_wrlock(), pthread_rwlock_trywrlock() - lock or attempt to lock a read-write lock for writ-

ing

SYNOPSIS

#include <pthread.h>

int pthread_rwlock_wrlock(

pthread_rwlock_t *rwlock

);

int pthread_rwlock_trywrlock(

pthread_rwlock_t *rwlock

);

PARAMETERS

rwlock Pointer to the read-write lock to be locked for writing.

DESCRIPTION

The

pthread_rwlock_wrlock()

function applies a write lock to the read-write lock object referenced

by rwlock . The calling thread acquires the write lock if no other thread (reader or writer) holds the

read-write lock rwlock . Otherwise, the thread blocks (that is, it does not return from the

pthread_rwlock_wrlock()

call) until it can acquire the lock. Results are undeﬁned if the calling

thread holds the read-write lock (whether a read or a write lock) at the time the call is made.

The function

pthread_rwlock_trywrlock()

applies a write lock as in the

pthread_rwlock_wrlock()

function with the exception that the function fails if any thread

currently holds rwlock (for reading or writing).

Results are undeﬁned if any of these functions are called with an uninitialized read-write lock.

If a signal is delivered to a thread waiting for a read-write lock, upon return from the signal handler, the

thread shall resume waiting for the read-write lock as if it was not interrupted.

RETURN VALUE

Upon successful completion,

pthread_rwlock_wrlock()

and pthread_rwlock_trywrlock()

return zero. Otherwise, an error number is returned to indicate the error (the errno variable is not set).

ERRORS

If any of the following occur, the

pthread_rwlock_trywrlock()

function returns the corresponding

error number:

[EBUSY] The read-write lock rwlock could not be acquired for writing because it was already

locked for reading or writing.

For each of the following conditions, if the condition is detected, the

pthread_rwlock_wrlock()

and

pthread_rwlock_trywrlock() functions return the corresponding error number:

[EINVAL] The value speciﬁed by rwlock does not refer to an initialized read-write lock.

[EDEADLK] The current thread already owns the read-write lock for reading or writing.

AUTHOR

pthread_rwlock_wrlock() and pthread_rwlock_trywrlock()

were developed by X/Open.