отменить выполнение потока (cancel execution of a thread)
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_cancel — cancel execution of a thread
Синопсис (Synopsis)
#include <pthread.h>
int pthread_cancel(pthread_t thread);
Описание (Description)
The pthread_cancel() function shall request that thread be
canceled. The target thread's cancelability state and type
determines when the cancellation takes effect. When the
cancellation is acted on, the cancellation cleanup handlers for
thread shall be called. When the last cancellation cleanup
handler returns, the thread-specific data destructor functions
shall be called for thread. When the last destructor function
returns, thread shall be terminated.
The cancellation processing in the target thread shall run
asynchronously with respect to the calling thread returning from
pthread_cancel().
Возвращаемое значение (Return value)
If successful, the pthread_cancel() function shall return zero;
otherwise, an error number shall be returned to indicate the
error.
Ошибки (Error)
The pthread_cancel() 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)
Two alternative functions were considered for sending the
cancellation notification to a thread. One would be to define a
new SIGCANCEL signal that had the cancellation semantics when
delivered; the other was to define the new pthread_cancel()
function, which would trigger the cancellation semantics.
The advantage of a new signal was that so much of the delivery
criteria were identical to that used when trying to deliver a
signal that making cancellation notification a signal was seen as
consistent. Indeed, many implementations implement cancellation
using a special signal. On the other hand, there would be no
signal functions that could be used with this signal except
pthread_kill(), and the behavior of the delivered cancellation
signal would be unlike any previously existing defined signal.
The benefits of a special function include the recognition that
this signal would be defined because of the similar delivery
criteria and that this is the only common behavior between a
cancellation request and a signal. In addition, the cancellation
delivery mechanism does not have to be implemented as a signal.
There are also strong, if not stronger, parallels with language
exception mechanisms than with signals that are potentially
obscured if the delivery mechanism is visibly closer to signals.
In the end, it was considered that as there were so many
exceptions to the use of the new signal with existing signals
functions it would be misleading. A special function has resolved
this problem. This function was carefully defined so that an
implementation wishing to provide the cancellation functions on
top of signals could do so. The special function also means that
implementations are not obliged to implement cancellation with
signals.
If an implementation detects use of a thread ID after the end of
its lifetime, it is recommended that the function should fail and
report an [ESRCH] error.
Будущие направления (Future directions)
None.
Смотри также (See also)
pthread_exit(3p), pthread_cond_timedwait(3p), pthread_join(3p),
pthread_setcancelstate(3p)
The Base Definitions volume of POSIX.1‐2017, pthread.h(0p)
