PROLOG | NAME | SYNOPSIS | DESCRIPTION | RETURN VALUE | ERRORS | EXAMPLES | APPLICATION USAGE | RATIONALE | FUTURE DIRECTIONS | SEE ALSO | COPYRIGHT

PTHREAD_RWLOCK_DESTROY(3P)POSIX Programmer's ManualTHREAD_RWLOCK_DESTROY(3P)

PROLOG         top

       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         top

       pthread_rwlock_destroy, pthread_rwlock_init — destroy and initialize
       a read-write lock object

SYNOPSIS         top

       #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;

DESCRIPTION         top

       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.

RETURN VALUE         top

       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.

ERRORS         top

       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.

EXAMPLES         top

       None.

APPLICATION USAGE         top

       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.

RATIONALE         top

       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.

FUTURE DIRECTIONS         top

       None.

SEE ALSO         top

       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)

COPYRIGHT         top

       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)