запись объекта блокировки для записи (write lock object for writing)
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_rwlock_trywrlock, pthread_rwlock_wrlock — lock a read-
write lock object for writing
Синопсис (Synopsis)
#include <pthread.h>
int pthread_rwlock_trywrlock(pthread_rwlock_t *rwlock);
int pthread_rwlock_wrlock(pthread_rwlock_t *rwlock);
Описание (Description)
The pthread_rwlock_trywrlock() function shall apply a write lock
like the pthread_rwlock_wrlock() function, with the exception
that the function shall fail if any thread currently holds rwlock
(for reading or writing).
The pthread_rwlock_wrlock() function shall apply a write lock to
the read-write lock referenced by rwlock. The calling thread
shall acquire the write lock if no thread (reader or writer)
holds the read-write lock rwlock. Otherwise, if another thread
holds the read-write lock rwlock, the calling thread shall block
until it can acquire the lock. If a deadlock condition occurs or
the calling thread already owns the read-write lock for writing
or reading, the call shall either deadlock or return [EDEADLK].
Results are undefined if any of these functions are called with
an uninitialized read-write lock.
If a signal is delivered to a thread waiting for a read-write
lock for writing, upon return from the signal handler the thread
resumes waiting for the read-write lock for writing as if it was
not interrupted.
Возвращаемое значение (Return value)
The pthread_rwlock_trywrlock() function shall return zero if the
lock for writing on the read-write lock object referenced by
rwlock is acquired. Otherwise, an error number shall be returned
to indicate the error.
If successful, the pthread_rwlock_wrlock() function shall return
zero; otherwise, an error number shall be returned to indicate
the error.
Ошибки (Error)
The pthread_rwlock_trywrlock() function shall fail if:
EBUSY The read-write lock could not be acquired for writing
because it was already locked for reading or writing.
The pthread_rwlock_wrlock() function may fail if:
EDEADLK
A deadlock condition was detected or the current thread
already owns the read-write lock for writing or reading.
These functions shall not return an error code of [EINTR].
The following sections are informative.
Примеры (Examples)
None.
Использование в приложениях (Application usage)
Applications using these functions may be subject to priority
inversion, as discussed in the Base Definitions volume of
POSIX.1‐2017, Section 3.291, Priority Inversion.
Обоснование (Rationale)
If an implementation detects that the value specified by the
rwlock argument to pthread_rwlock_trywrlock() or
pthread_rwlock_wrlock() does not refer to an initialized read-
write lock object, it is recommended that the function should
fail and report an [EINVAL] error.
Будущие направления (Future directions)
None.
Смотри также (See also)
pthread_rwlock_destroy(3p), pthread_rwlock_rdlock(3p),
pthread_rwlock_timedrdlock(3p), pthread_rwlock_timedwrlock(3p),
pthread_rwlock_unlock(3p)
The Base Definitions volume of POSIX.1‐2017, Section 3.291,
Priority Inversion, Section 4.12, Memory Synchronization,
pthread.h(0p)
