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_mutexattr_gettype, pthread_mutexattr_settype — get and set the mutex type attribute

SYNOPSIS

       #include <pthread.h>

       int pthread_mutexattr_gettype(const pthread_mutexattr_t *restrict attr,
           int *restrict type);
       int pthread_mutexattr_settype(pthread_mutexattr_t *attr, int type);

DESCRIPTION

       The  pthread_mutexattr_gettype()  and  pthread_mutexattr_settype() functions, respectively, shall get and
       set the mutex type attribute. This attribute is set in the type parameter to these functions. The default
       value of the type attribute is PTHREAD_MUTEX_DEFAULT.

       The type of mutex is contained in the type attribute of the mutex attributes. Valid mutex types include:

              PTHREAD_MUTEX_NORMAL PTHREAD_MUTEX_ERRORCHECK PTHREAD_MUTEX_RECURSIVE PTHREAD_MUTEX_DEFAULT

       The  mutex  type  affects the behavior of calls which lock and unlock the mutex. See pthread_mutex_lock()
       for details. An implementation may map PTHREAD_MUTEX_DEFAULT to one of the other mutex types.

       The behavior is undefined if the value specified by the attr argument to  pthread_mutexattr_gettype()  or
       pthread_mutexattr_settype() does not refer to an initialized mutex attributes object.

RETURN VALUE

       Upon  successful  completion,  the  pthread_mutexattr_gettype()  function shall return zero and store the
       value of the type attribute of attr into the object referenced by the type parameter. Otherwise, an error
       shall be returned to indicate the error.

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

ERRORS

       The pthread_mutexattr_settype() function shall fail if:

       EINVAL The value type is invalid.

       These functions shall not return an error code of [EINTR].

       The following sections are informative.

EXAMPLES

       None.

APPLICATION USAGE

       It is advised that an application should not use a PTHREAD_MUTEX_RECURSIVE mutex with condition variables
       because  the  implicit  unlock  performed  for  a pthread_cond_timedwait() or pthread_cond_wait() may not
       actually release the mutex (if it had been locked multiple times). If this happens, no other  thread  can
       satisfy the condition of the predicate.

RATIONALE

       If an implementation detects that the value specified by the attr argument to pthread_mutexattr_gettype()
       or pthread_mutexattr_settype()  does  not  refer  to  an  initialized  mutex  attributes  object,  it  is
       recommended that the function should fail and report an [EINVAL] error.

FUTURE DIRECTIONS

       None.

SEE ALSO

       pthread_cond_timedwait(), pthread_mutex_lock()

       The Base Definitions volume of POSIX.1‐2008, <pthread.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 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 .