'\" te .\" Copyright (c) 2008, 2012, Oracle and/or its affiliates. All rights reserved. .\" Copyright (c) 2001, the Institute of Electrical and Electronics Engineers, Inc. and The Open Group. All Rights Reserved. .\" Copyright 1991, 1992, 1994, The X/Open Company Ltd. .\" Sun Microsystems, Inc. gratefully acknowledges The Open Group for permission to reproduce portions of its copyrighted documentation. Original documentation from The Open Group can be obtained online at http://www.opengroup.org/bookstore/. .\" The Institute of Electrical and Electronics Engineers and The Open Group, have given us permission to reprint portions of their documentation. In the following statement, the phrase "this text" refers to portions of the system documentation. Portions of this text are reprinted and reproduced in electronic form in the Sun OS Reference Manual, from IEEE Std 1003.1, 2004 Edition, Standard for Information Technology -- Portable Operating System Interface (POSIX), The Open Group Base Specifications Issue 6, Copyright (C) 2001-2004 by the Institute of Electrical and Electronics Engineers, Inc and The Open Group. In the event of any discrepancy between these versions and the original IEEE and The Open Group Standard, the original IEEE and The Open Group Standard is the referee document. The original Standard can be obtained online at http://www.opengroup.org/unix/online.html. This notice shall appear on any product containing this material. .TH pthread_rwlock_wrlock 3C "11 Jan 2012" "SunOS 5.11" "Standard C Library Functions" .SH NAME pthread_rwlock_wrlock, pthread_rwlock_trywrlock \- lock or attempt to lock read-write lock object for writing .SH SYNOPSIS .LP .nf cc -mt [ \fIflag\fR... ] \fIfile\fR... [ \fIlibrary\fR... ] #include \fBint\fR \fBpthread_rwlock_wrlock\fR(\fBpthread_rwlock_t\fR \fI*rwlock\fR); .fi .LP .nf \fBint\fR \fBpthread_rwlock_trywrlock\fR(\fBpthread_rwlock_t\fR \fI*rwlock\fR); .fi .SH DESCRIPTION .sp .LP The \fBpthread_rwlock_wrlock()\fR function applies a write lock to the read-write lock referenced by \fIrwlock\fR. The calling thread acquires the write lock if no other thread (reader or writer) holds the read-write lock \fIrwlock\fR. Otherwise, the thread blocks until it can acquire the lock. .sp .LP The \fBpthread_rwlock_trywrlock()\fR function applies a write lock like the \fBpthread_rwlock_wrlock()\fR function, with the exception that the function fails if any thread currently holds \fIrwlock\fR (for reading or writing). .sp .LP Writers are favored over readers of the same priority to avoid writer starvation. See \fBpthread_rwlock_rdlock\fR(3C). .sp .LP Results are undefined if any of these functions are called with an uninitialized read-write lock. .sp .LP If a signal is delivered to a thread waiting for a read-write lock for writing, upon return from the signal handler the thread resumes waiting for the read-write lock for writing as if it was not interrupted. .SH RETURN VALUES .sp .LP If successful, the \fBpthread_rwlock_wrlock()\fR function returns \fB0\fR. Otherwise, an error number is returned to indicate the error. .sp .LP The \fBpthread_rwlock_trywrlock()\fR function returns \fB0\fR if the lock for writing on the read-write lock object referenced by \fIrwlock\fR is acquired. Otherwise an error number is returned to indicate the error. .SH ERRORS .sp .LP The \fBpthread_rwlock_wrlock()\fR function will fail if: .sp .ne 2 .mk .na \fB\fBEDEADLK\fR\fR .ad .RS 11n .rt The current thread already owns the read-write lock for writing or reading. .RE .sp .LP The \fBpthread_rwlock_trywrlock()\fR function will fail if: .sp .ne 2 .mk .na \fB\fBEBUSY\fR\fR .ad .RS 9n .rt The read-write lock could not be acquired for writing because it was already locked for reading or writing. .RE .SH ATTRIBUTES .sp .LP See \fBattributes\fR(5) for descriptions of the following attributes: .sp .sp .TS tab() box; cw(2.75i) |cw(2.75i) lw(2.75i) |lw(2.75i) . ATTRIBUTE TYPEATTRIBUTE VALUE _ Interface StabilityCommitted _ MT-LevelMT-Safe _ StandardSee \fBstandards\fR(5). .TE .SH SEE ALSO .sp .LP \fBpthread_rwlock_init\fR(3C), \fBpthread_rwlock_unlock\fR(3C), \fBpthread_rwlockattr_init\fR(3C), \fBpthread_rwlock_rdlock\fR(3C), \fBattributes\fR(5), \fBstandards\fR(5)