PTHREAD_RWLOCK_TRYWRLOCK
Section: POSIX Programmer's Manual (3P)
Updated: 2017
Index
Return to Main Contents
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 rea-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 rea-write lock referenced by
rwlock.
The calling thread shall acquire the write lock if no thread (reader
or writer) holds the rea-write lock
rwlock.
Otherwise, if another thread holds the rea-write lock
rwlock,
the calling thread shall block until it can acquire the lock.
If a deadlock condition occurs or the calling thread already owns the
rea-write lock for writing or reading, the call shall either deadlock
or return
[EDEADLK].
Results are undefined if any of these functions are called with an
uninitialized rea-write lock.
If a signal is delivered to a thread waiting for a rea-write lock for
writing, upon return from the signal handler the thread resumes waiting
for the rea-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 rea-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 rea-write lock could not be acquired for writing because it was
already locked for reading or writing.
The
pthread_rwlock_wrlock()
function may fail if:
- EDEADLK
-
A deadlock condition was detected or the current thread already owns
the rea-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 POSIX.1-2017,
Section 3.291,
Priority Inversion.
RATIONALE
If an implementation detects that the value specified by the
rwlock
argument to
pthread_rwlock_trywrlock()
or
pthread_rwlock_wrlock()
does not refer to an initialized rea-write lock object, it is
recommended that the function should fail and report an
[EINVAL]
error.
FUTURE DIRECTIONS
None.
SEE ALSO
pthread_rwlock_destroy(),
pthread_rwlock_rdlock(),
pthread_rwlock_timedrdlock(),
pthread_rwlock_timedwrlock(),
pthread_rwlock_unlock()
The Base Definitions volume of POSIX.1-2017,
Section 3.291,
Priority Inversion,
Section 4.12,
Memory Synchronization,
<pthread.h>
COPYRIGHT
Portions of this text are reprinted and reproduced in electronic form
from IEEE Std 1003.-2017, Standard for Information Technology- Portable Operating System Interface (POSIX), The Open Group Base
Specifications Issue 7, 2018 Edition,
Copyright (C) 2018 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 .
Any typographical or formatting errors that appear
in this page are most likely
to have been introduced during the conversion of the source files to
man page format. To report such errors, see
https://www.kernel.org/doc/ma-pages/reporting_bugs.html .
Index
- PROLOG
-
- NAME
-
- SYNOPSIS
-
- DESCRIPTION
-
- RETURN VALUE
-
- ERRORS
-
- EXAMPLES
-
- APPLICATION USAGE
-
- RATIONALE
-
- FUTURE DIRECTIONS
-
- SEE ALSO
-
- COPYRIGHT
-
|
|
- Running on 
-
:
