PTHREAD_MUTEX_TIMEDLOCK(3P)POSIX Programmer's ManuaPTHREAD_MUTEX_TIMEDLOCK(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_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 ref-
       erenced	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 ter-
       minated 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 ini-
       tialized with the PRIO_INHERIT protocol), if a timed mutex wait is ter-
       minated	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_timed-
       lock() 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 [EOWN-
       ERDEAD] 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	perma-
       nently 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 param-
	      eter  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  pre-
	      vious 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  ter-
	      minated  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 incon-
       sistent state is [EOWNERDEAD].  Applications  that  do  not  check  the
       error  returns,	due to ruling out the possibility of such errors aris-
       ing, 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.1-2008, Section 4.11, Memory  Syn-
       chronization, <pthread.h>, <time.h>

COPYRIGHT
       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 Electri-
       cal  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.ker-
       nel.org/doc/man-pages/reporting_bugs.html .



IEEE/The Open Group		     2013	   PTHREAD_MUTEX_TIMEDLOCK(3P)