PTHREAD_MUTEXATTR_GETTYPE(3)POSIX Programmer's ManuaPlTHREAD_MUTEXATTR_GETTYPE(3)



PROLOG
       This manual page is part of the POSIX Programmer's Manual.  The OS
       implementation of this interface may differ (consult the corresponding
       OS manual page for details of OS behavior), or the interface may not be
       implemented on OS.

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 .



IEEE/The Open Group                  2017         PTHREAD_MUTEXATTR_GETTYPE(3)
