PTHREAD_MUTEXATTR(3) Library Functions Manual PTHREAD_MUTEXATTR(3)
NAME
pthread_mutexattr_init, pthread_mutexattr_destroy, pthread_mutex-
attr_settype, pthread_mutexattr_gettype - mutex creation attributes
SYNOPSIS
#include <pthread.h>
int pthread_mutexattr_init(pthread_mutexattr_t *attr);
int pthread_mutexattr_destroy(pthread_mutexattr_t *attr);
int pthread_mutexattr_settype(pthread_mutexattr_t *attr, int kind);
int pthread_mutexattr_gettype(const pthread_mutexattr_t *attr, int
*kind);
DESCRIPTION
Mutex attributes can be specified at mutex creation time, by passing a
mutex attribute object as second argument to pthread_mutex_init(3).
Passing NULL is equivalent to passing a mutex attribute object with all
attributes set to their default values.
pthread_mutexattr_init initializes the mutex attribute object attr and
fills it with default values for the attributes.
pthread_mutexattr_destroy destroys a mutex attribute object, which must
not be reused until it is reinitialized. pthread_mutexattr_destroy does
nothing in the LinuxThreads implementation.
LinuxThreads supports only one mutex attribute: the mutex kind, which
is either PTHREAD_MUTEX_FAST_NP for ``fast'' mutexes, PTHREAD_MUTEX_RE-
CURSIVE_NP for ``recursive'' mutexes, or PTHREAD_MUTEX_ERRORCHECK_NP
for ``error checking'' mutexes. As the NP suffix indicates, this is a
non-portable extension to the POSIX standard and should not be employed
in portable programs.
The mutex kind determines what happens if a thread attempts to lock a
mutex it already owns with pthread_mutex_lock(3). If the mutex is of
the ``fast'' kind, pthread_mutex_lock(3) simply suspends the calling
thread forever. If the mutex is of the ``error checking'' kind,
pthread_mutex_lock(3) returns immediately with the error code EDEADLK.
If the mutex is of the ``recursive'' kind, the call to pthread_mu-
tex_lock(3) returns immediately with a success return code. The number
of times the thread owning the mutex has locked it is recorded in the
mutex. The owning thread must call pthread_mutex_unlock(3) the same
number of times before the mutex returns to the unlocked state.
The default mutex kind is ``fast'', that is, PTHREAD_MUTEX_FAST_NP.
pthread_mutexattr_settype sets the mutex kind attribute in attr to the
value specified by kind.
pthread_mutexattr_gettype retrieves the current value of the mutex kind
attribute in attr and stores it in the location pointed to by kind.
RETURN VALUE
pthread_mutexattr_init, pthread_mutexattr_destroy and pthread_mutex-
attr_gettype always return 0.
pthread_mutexattr_settype returns 0 on success and a non-zero error
code on error.
ERRORS
On error, pthread_mutexattr_settype returns the following error code:
EINVAL kind is neither PTHREAD_MUTEX_FAST_NP nor PTHREAD_MUTEX_RECUR-
SIVE_NP nor PTHREAD_MUTEX_ERRORCHECK_NP
AUTHOR
Xavier Leroy <Xavier.Leroy@inria.fr>
SEE ALSO
pthread_mutex_init(3), pthread_mutex_lock(3), pthread_mutex_unlock(3).
LinuxThreads PTHREAD_MUTEXATTR(3)
Generated by dwww version 1.15 on Mon Jun 24 18:52:20 CEST 2024.