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

PTHREAD_RWLOCK_TRYWRLOCK(3P)SIX Programmer's ManualREAD_RWLOCK_TRYWRLOCK(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_trywrlock, pthread_rwlock_wrlock — lock a read-write
       lock object for writing

SYNOPSIS         top

       #include <pthread.h>

       int pthread_rwlock_trywrlock(pthread_rwlock_t *rwlock);
       int pthread_rwlock_wrlock(pthread_rwlock_t *rwlock);

DESCRIPTION         top

       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         top

       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         top

       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_wrlock() function may fail if:

       EDEADLK
              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 [EINTR].

       The following sections are informative.

EXAMPLES         top

       None.

APPLICATION USAGE         top

       Applications using these 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_trywrlock() or pthread_rwlock_wrlock()
       does not refer to an initialized read-write lock object, it is
       recommended that the function should fail and report an [EINVAL]
       error.

FUTURE DIRECTIONS         top

       None.

SEE ALSO         top

       pthread_rwlock_destroy(3p), pthread_rwlock_rdlock(3p),
       pthread_rwlock_timedrdlock(3p), pthread_rwlock_timedwrlock(3p),
       pthread_rwlock_unlock(3p)

       The Base Definitions volume of POSIX.1‐2008, Section 3.287,  Priority
       Inversion, Section 4.11, Memory Synchronization, 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_TRYWRLOCK(3P)

Pages that refer to this page: pthread.h(0p)pthread_rwlock_destroy(3p)pthread_rwlock_rdlock(3p)pthread_rwlock_timedrdlock(3p)pthread_rwlock_timedwrlock(3p)pthread_rwlock_unlock(3p)pthread_rwlock_wrlock(3p)