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PTHREAD_RWLOCK_DESTROY(3P)POSIX Programmer's ManualTHREAD_RWLOCK_DESTROY(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.
pthread_rwlock_destroy, pthread_rwlock_init — destroy and initialize
a read-write lock object
#include <pthread.h>
int pthread_rwlock_destroy(pthread_rwlock_t *rwlock);
int pthread_rwlock_init(pthread_rwlock_t *restrict rwlock,
const pthread_rwlockattr_t *restrict attr);
pthread_rwlock_t rwlock = PTHREAD_RWLOCK_INITIALIZER;
The pthread_rwlock_destroy() function shall destroy the read-write
lock object referenced by rwlock and release any resources used by
the lock. The effect of subsequent use of the lock is undefined until
the lock is reinitialized by another call to pthread_rwlock_init().
An implementation may cause pthread_rwlock_destroy() to set the
object referenced by rwlock to an invalid value. Results are
undefined if pthread_rwlock_destroy() is called when any thread holds
rwlock. Attempting to destroy an uninitialized read-write lock
results in undefined behavior.
The pthread_rwlock_init() function shall allocate any resources
required to use the read-write lock referenced by rwlock and
initializes the lock to an unlocked state with attributes referenced
by attr. If attr is NULL, the default read-write lock attributes
shall be used; the effect is the same as passing the address of a
default read-write lock attributes object. Once initialized, the lock
can be used any number of times without being reinitialized. Results
are undefined if pthread_rwlock_init() is called specifying an
already initialized read-write lock. Results are undefined if a read-
write lock is used without first being initialized.
If the pthread_rwlock_init() function fails, rwlock shall not be
initialized and the contents of rwlock are undefined.
Only the object referenced by rwlock may be used for performing
synchronization. The result of referring to copies of that object in
calls to pthread_rwlock_destroy(), pthread_rwlock_rdlock(),
pthread_rwlock_timedrdlock(), pthread_rwlock_timedwrlock(),
pthread_rwlock_tryrdlock(), pthread_rwlock_trywrlock(),
pthread_rwlock_unlock(), or pthread_rwlock_wrlock() is undefined.
In cases where default read-write lock attributes are appropriate,
the macro PTHREAD_RWLOCK_INITIALIZER can be used to initialize read-
write locks. The effect shall be equivalent to dynamic initialization
by a call to pthread_rwlock_init() with the attr parameter specified
as NULL, except that no error checks are performed.
The behavior is undefined if the value specified by the attr argument
to pthread_rwlock_init() does not refer to an initialized read-write
lock attributes object.
If successful, the pthread_rwlock_destroy() and pthread_rwlock_init()
functions shall return zero; otherwise, an error number shall be
returned to indicate the error.
The pthread_rwlock_init() function shall fail if:
EAGAIN The system lacked the necessary resources (other than memory)
to initialize another read-write lock.
ENOMEM Insufficient memory exists to initialize the read-write lock.
EPERM The caller does not have the privilege to perform the
operation.
These functions shall not return an error code of [EINTR].
The following sections are informative.
None.
Applications using these and related read-write lock functions may be
subject to priority inversion, as discussed in the Base Definitions
volume of POSIX.1‐2008, Section 3.287, Priority Inversion.
If an implementation detects that the value specified by the rwlock
argument to pthread_rwlock_destroy() does not refer to an initialized
read-write lock object, it is recommended that the function should
fail and report an [EINVAL] error.
If an implementation detects that the value specified by the attr
argument to pthread_rwlockr_init() does not refer to an initialized
read-write lock attributes object, it is recommended that the
function should fail and report an [EINVAL] error.
If an implementation detects that the value specified by the rwlock
argument to pthread_rwlock_destroy() or pthread_rwlock_init() refers
to a locked read-write lock object, or detects that the value
specified by the rwlock argument to pthread_rwlock_init() refers to
an already initialized read-write lock object, it is recommended that
the function should fail and report an [EBUSY] error.
None.
pthread_rwlock_rdlock(3p), pthread_rwlock_timedrdlock(3p),
pthread_rwlock_timedwrlock(3p), pthread_rwlock_trywrlock(3p),
pthread_rwlock_unlock(3p)
The Base Definitions volume of POSIX.1‐2008, Section 3.287, Priority
Inversion, pthread.h(0p)
Portions of this text are reprinted and reproduced in electronic form
from IEEE Std 1003.1, 2013 Edition, Standard for Information
Technology -- Portable Operating System Interface (POSIX), The Open
Group Base Specifications Issue 7, Copyright (C) 2013 by the
Institute of Electrical and Electronics Engineers, Inc and The Open
Group. (This is POSIX.1-2008 with the 2013 Technical Corrigendum 1
applied.) 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.unix.org/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/man-pages/reporting_bugs.html .
IEEE/The Open Group 2013 PTHREAD_RWLOCK_DESTROY(3P)
Pages that refer to this page: pthread.h(0p), pthread_rwlockattr_destroy(3p), pthread_rwlockattr_getpshared(3p), pthread_rwlock_rdlock(3p), pthread_rwlock_timedrdlock(3p), pthread_rwlock_timedwrlock(3p), pthread_rwlock_trywrlock(3p), pthread_rwlock_unlock(3p)