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.1‐2017, <pthread.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 .