bionic (3) pthread_rwlock_timedrdlock.3posix.gz

Provided by: manpages-posix-dev_2013a-2_all bug

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_timedrdlock — lock a read-write lock for reading


SYNOPSIS
       #include <pthread.h>
       #include <time.h>

       int pthread_rwlock_timedrdlock(pthread_rwlock_t *restrict rwlock,
           const struct timespec *restrict abstime);


DESCRIPTION
       The  pthread_rwlock_timedrdlock()  function  shall apply a read lock to the read-write lock referenced by
       rwlock as in the pthread_rwlock_rdlock() function. However,  if  the  lock  cannot  be  acquired  without
       waiting  for  other  threads to unlock the lock, this wait shall be terminated when the specified timeout
       expires. The timeout shall expire when the absolute time specified by abstime passes, as measured by  the
       clock  on  which timeouts are based (that is, when the value of that clock equals or exceeds abstime), or
       if the absolute time specified by abstime has already been passed at the time of the call.

       The timeout shall be based on the CLOCK_REALTIME clock.  The resolution  of  the  timeout  shall  be  the
       resolution  of  the CLOCK_REALTIME clock. The timespec data type is defined in the <time.h> header. Under
       no circumstances shall the function fail with a timeout if the lock  can  be  acquired  immediately.  The
       validity of the abstime parameter need not be checked if the lock can be immediately acquired.

       If  a signal that causes a signal handler to be executed is delivered to a thread blocked on a read-write
       lock via a call to pthread_rwlock_timedrdlock(), upon return from the signal  handler  the  thread  shall
       resume waiting for the lock as if it was not interrupted.

       The  calling  thread  may  deadlock if at the time the call is made it holds a write lock on rwlock.  The
       results are undefined if this function is called with an uninitialized read-write lock.


RETURN VALUE
       The pthread_rwlock_timedrdlock() function shall return zero if the lock for  reading  on  the  read-write
       lock  object  referenced  by rwlock is acquired. Otherwise, an error number shall be returned to indicate
       the error.


ERRORS
       The pthread_rwlock_timedrdlock() function shall fail if:

       ETIMEDOUT
              The lock could not be acquired before the specified timeout expired.

       The pthread_rwlock_timedrdlock() function may fail if:

       EAGAIN The read lock could not be acquired because the maximum number of read locks  for  lock  would  be
              exceeded.

       EDEADLK
              A deadlock condition was detected or the calling thread already holds a write lock on rwlock.

       EINVAL The abstime nanosecond value is less than zero or greater than or equal to 1000 million.

       This function shall not return an error code of [EINTR].

       The following sections are informative.


EXAMPLES
       None.


APPLICATION USAGE
       Applications  using  this  function  may  be  subject  to  priority  inversion,  as discussed in the Base
       Definitions volume of POSIX.1‐2008, Section 3.287, Priority Inversion.


RATIONALE
       If   an   implementation   detects   that   the   value   specified   by   the   rwlock    argument    to
       pthread_rwlock_timedrdlock()  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(), pthread_rwlock_rdlock(), pthread_rwlock_timedwrlock(),
       pthread_rwlock_trywrlock(), pthread_rwlock_unlock()

       The  Base  Definitions  volume  of  POSIX.1‐2008, Section 3.287, Priority Inversion, Section 4.11, Memory
       Synchronization, <pthread.h>, <time.h>


       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 .