синхронизироваться у барьера (synchronize at a barrier)
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_barrier_wait — synchronize at a barrier
Синопсис (Synopsis)
#include <pthread.h>
int pthread_barrier_wait(pthread_barrier_t *barrier);
Описание (Description)
The pthread_barrier_wait() function shall synchronize
participating threads at the barrier referenced by barrier. The
calling thread shall block until the required number of threads
have called pthread_barrier_wait() specifying the barrier.
When the required number of threads have called
pthread_barrier_wait() specifying the barrier, the constant
PTHREAD_BARRIER_SERIAL_THREAD shall be returned to one
unspecified thread and zero shall be returned to each of the
remaining threads. At this point, the barrier shall be reset to
the state it had as a result of the most recent
pthread_barrier_init() function that referenced it.
The constant PTHREAD_BARRIER_SERIAL_THREAD is defined in
<pthread.h> and its value shall be distinct from any other value
returned by pthread_barrier_wait().
The results are undefined if this function is called with an
uninitialized barrier.
If a signal is delivered to a thread blocked on a barrier, upon
return from the signal handler the thread shall resume waiting at
the barrier if the barrier wait has not completed (that is, if
the required number of threads have not arrived at the barrier
during the execution of the signal handler); otherwise, the
thread shall continue as normal from the completed barrier wait.
Until the thread in the signal handler returns from it, it is
unspecified whether other threads may proceed past the barrier
once they have all reached it.
A thread that has blocked on a barrier shall not prevent any
unblocked thread that is eligible to use the same processing
resources from eventually making forward progress in its
execution. Eligibility for processing resources shall be
determined by the scheduling policy.
Возвращаемое значение (Return value)
Upon successful completion, the pthread_barrier_wait() function
shall return PTHREAD_BARRIER_SERIAL_THREAD for a single
(arbitrary) thread synchronized at the barrier and zero for each
of the other threads. Otherwise, an error number shall be
returned to indicate the error.
Ошибки (Error)
This function shall not return an error code of [EINTR].
The following sections are informative.
Примеры (Examples)
None.
Использование в приложениях (Application usage)
Applications using this function 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
barrier argument to pthread_barrier_wait() does not refer to an
initialized barrier object, it is recommended that the function
should fail and report an [EINVAL] error.
Будущие направления (Future directions)
None.
Смотри также (See also)
pthread_barrier_destroy(3p)
The Base Definitions volume of POSIX.1‐2017, Section 3.291,
Priority Inversion, Section 4.12, Memory Synchronization,
pthread.h(0p)
