pthread_rwlock_trywrlock(3p) — Linux manual page

PTHREAD_...RYWRLOCK(3P) POSIX Programmer's ManualPTHREAD_...RYWRLOCK(3P)

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 read-
       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 read-write lock referenced by rwlock.  The calling thread
       shall acquire the write lock if no thread (reader or writer)
       holds the read-write lock rwlock.  Otherwise, if another thread
       holds the read-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 read-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 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

       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

       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

       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 read-
       write lock object, it is recommended that the function should
       fail and report an [EINVAL] error.

FUTURE DIRECTIONS

       None.

SEE ALSO

       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.1‐2017,  Section 3.291,
       Priority  Inversion,  Section   4.12,   Memory   Synchronization,
       pthread.h(0p)

COPYRIGHT

       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 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/man-pages/reporting_bugs.html .

IEEE/The Open Group               2017           PTHREAD_...RYWRLOCK(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)

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