Provides signal functionality.
class signal_set
Name |
Description |
---|---|
The type of the executor associated with the object. |
Name |
Description |
---|---|
Add a signal to a signal_set. |
|
Start an asynchronous operation to wait for a signal to be delivered. |
|
Cancel all operations associated with the signal set. |
|
Remove all signals from a signal_set. |
|
Get the executor associated with the object. |
|
(Deprecated: Use get_executor().) Get the io_context associated with the object. |
|
(Deprecated: Use get_executor().) Get the io_context associated with the object. |
|
Remove a signal from a signal_set. |
|
Construct a signal set without adding any signals. |
|
Destroys the signal set. |
The signal_set
class provides the ability to perform an asynchronous wait for one or more
signals to occur.
Distinct objects: Safe.
Shared objects: Unsafe.
Performing an asynchronous wait:
void handler( const asio::error_code& error, int signal_number) { if (!error) { // A signal occurred. } } ... // Construct a signal set registered for process termination. asio::signal_set signals(io_context, SIGINT, SIGTERM); // Start an asynchronous wait for one of the signals to occur. signals.async_wait(handler);
If a signal is registered with a signal_set
,
and the signal occurs when there are no waiting handlers, then the signal
notification is queued. The next async_wait operation on that signal_set
will dequeue the notification. If multiple notifications are queued, subsequent
async_wait operations dequeue them one at a time. Signal notifications are
dequeued in order of ascending signal number.
If a signal number is removed from a signal_set
(using the remove
or erase
member functions) then
any queued notifications for that signal are discarded.
The same signal number may be registered with different signal_set
objects. When the signal occurs, one handler is called for each signal_set
object.
Note that multiple registration only works for signals that are registered
using Asio. The application must not also register a signal handler using
functions such as signal()
or sigaction()
.
POSIX allows signals to be blocked using functions such as sigprocmask()
and pthread_sigmask()
. For signals to be delivered, programs
must ensure that any signals registered using signal_set
objects are unblocked in at least one thread.
Header: asio/signal_set.hpp
Convenience header: asio.hpp