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PTHREAD_RWLOCK_TRYWRLOCK
Section: POSIX Programmer's Manual (3P) Updated: 2003 Index
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PROLOG
This manual page is part of the POSIX Programmer's Manual.
The Linux implementation of this interface may differ (consult
the corresponding Linux manual page for details of Linux behavior),
or the interface may not be implemented on Linux.
NAME
pthread_rwlock_trywrlock, pthread_rwlock_wrlock - lock a read-write
lock object for writing
SYNOPSIS
#include <pthread.h>
int pthread_rwlock_trywrlock(pthread_rwlock_t *rwlock);
int pthread_rwlock_wrlock(pthread_rwlock_t *rwlock);
DESCRIPTION
The pthread_rwlock_trywrlock() function shall apply a write
lock like the pthread_rwlock_wrlock() function, with
the exception that the function shall fail if any thread currently
holds rwlock (for reading or writing).
The pthread_rwlock_wrlock() function shall apply a write lock
to the read-write lock 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 shall block until it can acquire the lock. The calling
thread may deadlock if at the time the call is made it holds the
read-write lock (whether a read or write lock).
Implementations may favor writers over readers to avoid writer starvation.
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
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.
RETURN VALUE
The pthread_rwlock_trywrlock() function shall return zero if
the lock for writing on the read-write lock object
referenced by rwlock is acquired. Otherwise, an error number
shall be returned to indicate the error.
If successful, the pthread_rwlock_wrlock() function shall return
zero; otherwise, an error number shall be returned to
indicate the error.
ERRORS
The pthread_rwlock_trywrlock() function shall fail if:
- EBUSY
-
The read-write lock could not be acquired for writing because it was
already locked for reading or writing.
The pthread_rwlock_trywrlock() and pthread_rwlock_wrlock()
functions may fail if:
- EINVAL
-
The value specified by rwlock does not refer to an initialized
read-write lock object.
The pthread_rwlock_wrlock() function may fail if:
- EDEADLK
-
The current thread already owns the read-write lock for writing or
reading.
These functions shall not return an error code of [EINTR].
The following sections are informative.
EXAMPLES
None.
APPLICATION USAGE
Applications using these functions may be subject to priority inversion,
as discussed in the Base Definitions volume of
IEEE Std 1003.1-2001, Section 3.285, Priority Inversion.
RATIONALE
None.
FUTURE DIRECTIONS
None.
SEE ALSO
pthread_rwlock_destroy(), pthread_rwlock_rdlock(), pthread_rwlock_timedrdlock(),
pthread_rwlock_timedwrlock(), pthread_rwlock_tryrdlock(),
pthread_rwlock_unlock(), the Base Definitions volume of IEEE Std 1003.1-2001,
<pthread.h>
COPYRIGHT
Portions of this text are reprinted and reproduced in electronic form
from IEEE Std 1003.1, 2003 Edition, Standard for Information Technology
-- Portable Operating System Interface (POSIX), The Open Group Base
Specifications Issue 6, Copyright (C) 2001-2003 by the Institute of
Electrical and Electronics Engineers, Inc and The Open Group. In the
event of any discrepancy between this version 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 .
Index
- PROLOG
-
- NAME
-
- SYNOPSIS
-
- DESCRIPTION
-
- RETURN VALUE
-
- ERRORS
-
- EXAMPLES
-
- APPLICATION USAGE
-
- RATIONALE
-
- FUTURE DIRECTIONS
-
- SEE ALSO
-
- COPYRIGHT
-
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