получить и установить атрибут типа мьютекса (get and set the mutex type attribute)
Пролог (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.
Имя (Name)
pthread_mutexattr_gettype, pthread_mutexattr_settype — get and
set the mutex type attribute
Синопсис (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);
Описание (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(3p) 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.
Возвращаемое значение (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.
Ошибки (Error)
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.
Примеры (Examples)
None.
Использование в приложениях (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.
Обоснование (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.
Будущие направления (Future directions)
None.
Смотри также (See also)
pthread_cond_timedwait(3p), pthread_mutex_lock(3p)
The Base Definitions volume of POSIX.1‐2017, pthread.h(0p)
