basic_signal_set::async

basic_signal_set::async_wait

Start an asynchronous operation to wait for a signal to be delivered.

template<
    typename SignalHandler>
void-or-deduced async_wait(
    SignalHandler && handler);

This function may be used to initiate an asynchronous wait against the signal set. It always returns immediately.

For each call to async_wait(), the supplied handler will be called exactly once. The handler will be called when:

One of the registered signals in the signal set occurs; or
The signal set was cancelled, in which case the handler is passed the error code asio::error::operation_aborted.

Parameters

handler

The handler to be called when the signal occurs. Copies will be made of the handler as required. The function signature of the handler must be:

void handler(
  const asio::error_code& error, // Result of operation.
  int signal_number // Indicates which signal occurred.
);

Regardless of whether the asynchronous operation completes immediately or not, the handler will not be invoked from within this function. Invocation of the handler will be performed in a manner equivalent to using asio::io_service::post().