2004-11-03 13:51:07 +00:00
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.\" Copyright (c) 2001-2003 The Open Group, All Rights Reserved
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2007-06-20 22:33:04 +00:00
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.TH "PTHREAD_RWLOCK_TRYWRLOCK" 3P 2003 "IEEE/The Open Group" "POSIX Programmer's Manual"
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2004-11-03 13:51:07 +00:00
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.\" pthread_rwlock_trywrlock
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2007-09-20 06:03:25 +00:00
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.SH PROLOG
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This manual page is part of the POSIX Programmer's Manual.
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The Linux implementation of this interface may differ (consult
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the corresponding Linux manual page for details of Linux behavior),
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or the interface may not be implemented on Linux.
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2004-11-03 13:51:07 +00:00
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.SH NAME
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pthread_rwlock_trywrlock, pthread_rwlock_wrlock \- lock a read-write
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lock object for writing
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.SH SYNOPSIS
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.LP
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\fB#include <pthread.h>
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.br
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.sp
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int pthread_rwlock_trywrlock(pthread_rwlock_t\fP \fI*rwlock\fP\fB);
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.br
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int pthread_rwlock_wrlock(pthread_rwlock_t\fP \fI*rwlock\fP\fB); \fP
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\fB
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.br
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\fP
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.SH DESCRIPTION
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.LP
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The \fIpthread_rwlock_trywrlock\fP() function shall apply a write
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lock like the \fIpthread_rwlock_wrlock\fP() function, with
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the exception that the function shall fail if any thread currently
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holds \fIrwlock\fP (for reading or writing).
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.LP
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The \fIpthread_rwlock_wrlock\fP() function shall apply a write lock
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to the read-write lock referenced by \fIrwlock\fP. The
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calling thread acquires the write lock if no other thread (reader
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or writer) holds the read-write lock \fIrwlock\fP. Otherwise,
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the thread shall block until it can acquire the lock. The calling
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thread may deadlock if at the time the call is made it holds the
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read-write lock (whether a read or write lock).
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.LP
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Implementations may favor writers over readers to avoid writer starvation.
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.LP
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Results are undefined if any of these functions are called with an
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uninitialized read-write lock.
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.LP
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If a signal is delivered to a thread waiting for a read-write lock
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for writing, upon return from the signal handler the thread
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resumes waiting for the read-write lock for writing as if it was not
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interrupted.
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.SH RETURN VALUE
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.LP
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The \fIpthread_rwlock_trywrlock\fP() function shall return zero if
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the lock for writing on the read-write lock object
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referenced by \fIrwlock\fP is acquired. Otherwise, an error number
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shall be returned to indicate the error.
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.LP
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If successful, the \fIpthread_rwlock_wrlock\fP() function shall return
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zero; otherwise, an error number shall be returned to
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indicate the error.
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.SH ERRORS
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.LP
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The \fIpthread_rwlock_trywrlock\fP() function shall fail if:
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.TP 7
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.B EBUSY
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The read-write lock could not be acquired for writing because it was
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already locked for reading or writing.
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.sp
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.LP
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The \fIpthread_rwlock_trywrlock\fP() and \fIpthread_rwlock_wrlock\fP()
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functions may fail if:
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.TP 7
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.B EINVAL
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The value specified by \fIrwlock\fP does not refer to an initialized
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read-write lock object.
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.sp
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.LP
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The \fIpthread_rwlock_wrlock\fP() function may fail if:
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.TP 7
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.B EDEADLK
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The current thread already owns the read-write lock for writing or
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reading.
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.sp
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.LP
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These functions shall not return an error code of [EINTR].
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.LP
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\fIThe following sections are informative.\fP
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.SH EXAMPLES
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.LP
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None.
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.SH APPLICATION USAGE
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.LP
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Applications using these functions may be subject to priority inversion,
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as discussed in the Base Definitions volume of
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IEEE\ Std\ 1003.1-2001, Section 3.285, Priority Inversion.
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.SH RATIONALE
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.LP
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None.
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.SH FUTURE DIRECTIONS
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.LP
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None.
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.SH SEE ALSO
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.LP
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2007-09-20 17:56:19 +00:00
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\fIpthread_rwlock_destroy\fP(), \fIpthread_rwlock_rdlock\fP(), \fIpthread_rwlock_timedrdlock\fP(),
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\fIpthread_rwlock_timedwrlock\fP(), \fIpthread_rwlock_tryrdlock\fP(),
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\fIpthread_rwlock_unlock\fP(), the Base Definitions volume of IEEE\ Std\ 1003.1-2001,
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2004-11-03 13:51:07 +00:00
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\fI<pthread.h>\fP
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.SH COPYRIGHT
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Portions of this text are reprinted and reproduced in electronic form
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from IEEE Std 1003.1, 2003 Edition, Standard for Information Technology
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-- Portable Operating System Interface (POSIX), The Open Group Base
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Specifications Issue 6, Copyright (C) 2001-2003 by the Institute of
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Electrical and Electronics Engineers, Inc and The Open Group. In the
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event of any discrepancy between this version and the original IEEE and
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The Open Group Standard, the original IEEE and The Open Group Standard
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is the referee document. The original Standard can be obtained online at
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http://www.opengroup.org/unix/online.html .
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