объект блокировки записи (write lock object)
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_unlock — unlock a read-write lock object
Синопсис (Synopsis)
#include <pthread.h>
int pthread_rwlock_unlock(pthread_rwlock_t *rwlock);
Описание (Description)
The pthread_rwlock_unlock() function shall release a lock held on
the read-write lock object referenced by rwlock. Results are
undefined if the read-write lock rwlock is not held by the
calling thread.
If this function is called to release a read lock from the read-
write lock object and there are other read locks currently held
on this read-write lock object, the read-write lock object
remains in the read locked state. If this function releases the
last read lock for this read-write lock object, the read-write
lock object shall be put in the unlocked state with no owners.
If this function is called to release a write lock for this read-
write lock object, the read-write lock object shall be put in the
unlocked state.
If there are threads blocked on the lock when it becomes
available, the scheduling policy shall determine which thread(s)
shall acquire the lock. If the Thread Execution Scheduling
option is supported, when threads executing with the scheduling
policies SCHED_FIFO, SCHED_RR, or SCHED_SPORADIC are waiting on
the lock, they shall acquire the lock in priority order when the
lock becomes available. For equal priority threads, write locks
shall take precedence over read locks. If the Thread Execution
Scheduling option is not supported, it is implementation-defined
whether write locks take precedence over read locks.
Results are undefined if this function is called with an
uninitialized read-write lock.
Возвращаемое значение (Return value)
If successful, the pthread_rwlock_unlock() function shall return
zero; otherwise, an error number shall be returned to indicate
the error.
Ошибки (Error)
The pthread_rwlock_unlock() function shall not return an error
code of [EINTR].
The following sections are informative.
Примеры (Examples)
None.
Использование в приложениях (Application usage)
None.
Обоснование (Rationale)
If an implementation detects that the value specified by the
rwlock argument to pthread_rwlock_unlock() does not refer to an
initialized read-write lock object, it is recommended that the
function should fail and report an [EINVAL] error.
If an implementation detects that the value specified by the
rwlock argument to pthread_rwlock_unlock() refers to a read-write
lock object for which the current thread does not hold a lock, it
is recommended that the function should fail and report an
[EPERM] 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_trywrlock(3p)
The Base Definitions volume of POSIX.1‐2017, Section 4.12, Memory
Synchronization, pthread.h(0p)
