Section: POSIX Programmer's Manual (3P)
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.
--- lock a read-write lock object for writing
int pthread_rwlock_trywrlock(pthread_rwlock_t *rwlock);
int pthread_rwlock_wrlock(pthread_rwlock_t *rwlock);
function shall apply a write lock like the
function, with the exception that the function shall fail if any thread
(for reading or writing).
function shall apply a write lock to the read-write lock referenced by
The calling thread shall acquire the write lock if no thread (reader
or writer) holds the read-write lock
Otherwise, if another thread holds the read-write lock
the calling thread shall block until it can acquire the lock.
If a deadlock condition occurs or the calling thread already owns the
read-write lock for writing or reading, the call shall either deadlock
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.
function shall return zero if the lock for writing on the read-write
lock object referenced by
is acquired. Otherwise, an error number shall be returned to indicate
If successful, the
function shall return zero; otherwise, an error number shall be
returned to indicate the error.
function shall fail if:
The read-write lock could not be acquired for writing because it was
already locked for reading or writing.
function may fail if:
A deadlock condition was detected or the current thread already owns
the read-write lock for writing or reading.
These functions shall not return an error code of
The following sections are informative.
Applications using these functions may be subject to priority inversion,
as discussed in the Base Definitions volume of POSIX.1-2017,
, Priority Inversion.
If an implementation detects that the value specified by the
does not refer to an initialized read-write lock object, it is
recommended that the function should fail and report an
The Base Definitions volume of POSIX.1-2017,
Section 3.291, Priority Inversion,
Section 4.12, Memory Synchronization,
Portions of this text are reprinted and reproduced in electronic form
from IEEE Std 1003.1-2017, 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
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