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_mutex_timedlock — lock a mutex

SYNOPSIS

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

       int pthread_mutex_timedlock(pthread_mutex_t *restrict mutex,
           const struct timespec *restrict abstime);

DESCRIPTION

       The  pthread_mutex_timedlock() function shall lock the mutex object referenced by mutex.  If the mutex is
       already  locked,  the  calling  thread  shall  block  until  the  mutex  becomes  available  as  in   the
       pthread_mutex_lock() function. If the mutex cannot be locked without waiting for another thread to unlock
       the mutex, 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 on which it is based. The timespec data type is defined in the <time.h> header.

       Under  no circumstance shall the function fail with a timeout if the mutex can be locked immediately. The
       validity of the abstime parameter need not be checked if the mutex can be locked immediately.

       As a consequence of the priority  inheritance  rules  (for  mutexes  initialized  with  the  PRIO_INHERIT
       protocol),  if a timed mutex wait is terminated because its timeout expires, the priority of the owner of
       the mutex shall be adjusted as necessary to reflect the fact that this thread  is  no  longer  among  the
       threads waiting for the mutex.

       If  mutex  is  a  robust  mutex and the process containing the owning thread terminated while holding the
       mutex lock, a call to pthread_mutex_timedlock() shall return the error value [EOWNERDEAD].  If mutex is a
       robust   mutex   and   the   owning   thread   terminated  while  holding  the  mutex  lock,  a  call  to
       pthread_mutex_timedlock() may return the error value [EOWNERDEAD] even if the process in which the owning
       thread  resides  has  not  terminated. In these cases, the mutex is locked by the thread but the state it
       protects is marked as inconsistent. The application should ensure that the state is made  consistent  for
       reuse and when that is complete call pthread_mutex_consistent().  If the application is unable to recover
       the state, it should unlock the mutex without a prior call to pthread_mutex_consistent(), after which the
       mutex is marked permanently unusable.

       If mutex does not refer to an initialized mutex object, the behavior is undefined.

RETURN VALUE

       If successful, the pthread_mutex_timedlock() function shall return zero; otherwise, an error number shall
       be returned to indicate the error.

ERRORS

       The pthread_mutex_timedlock() function shall fail if:

       EAGAIN The mutex could not be acquired because the maximum number of recursive locks for mutex  has  been
              exceeded.

       EDEADLK
              The mutex type is PTHREAD_MUTEX_ERRORCHECK and the current thread already owns the mutex.

       EINVAL The  mutex  was  created with the protocol attribute having the value PTHREAD_PRIO_PROTECT and the
              calling thread's priority is higher than the mutex' current priority ceiling.

       EINVAL The process or thread would have blocked, and the abstime parameter specified a nanoseconds  field
              value less than zero or greater than or equal to 1000 million.

       ENOTRECOVERABLE
              The state protected by the mutex is not recoverable.

       EOWNERDEAD
              The mutex is a robust mutex and the process containing the previous owning thread terminated while
              holding the mutex lock. The mutex lock shall be acquired by the calling thread and it is up to the
              new owner to make the state consistent.

       ETIMEDOUT
              The mutex could not be locked before the specified timeout expired.

       The pthread_mutex_timedlock() function may fail if:

       EDEADLK
              A deadlock condition was detected.

       EOWNERDEAD
              The  mutex  is  a  robust  mutex and the previous owning thread terminated while holding the mutex
              lock. The mutex lock shall be acquired by the calling thread and it is up to the new owner to make
              the state consistent.

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

       The following sections are informative.

EXAMPLES

       None.

APPLICATION USAGE

       Applications  that  have  assumed  that non-zero return values are errors will need updating for use with
       robust mutexes, since a valid return for a thread acquiring a  mutex  which  is  protecting  a  currently
       inconsistent  state is [EOWNERDEAD].  Applications that do not check the error returns, due to ruling out
       the possibility of such errors arising, should not use robust mutexes. If an application is  supposed  to
       work  with  normal  and  robust  mutexes,  it  should check all return values for error conditions and if
       necessary take appropriate action.

RATIONALE

       Refer to pthread_mutex_lock().

FUTURE DIRECTIONS

       None.

SEE ALSO

       pthread_mutex_destroy(), pthread_mutex_lock(), time()

       The Base Definitions volume of POSIX.1‐2017, Section 4.12, Memory Synchronization, <pthread.h>, <time.h>

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 .