PTHREAD_MUTEXATTR_GETTYPE(3POSIX Programmer's ManPTHREAD_MUTEXATTR_GETTYPE(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_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() func‐
tions, 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_RECUR‐
SIVE mutex with condition variables because the implicit unlock per‐
formed 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 predi‐
cate.
RATIONALE
If an implementation detects that the value specified by the attr argu‐
ment 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 ALSOpthread_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 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_MUTEXATTR_GETTYPE(3P)
