RFC: asio::io_service::async_stop() to handle signals

[giecrilj@…]

Problem statement

asio::io_service has no way of stopping from within a signal handler. Sending a signal to a daemon is a common way to controlling its behavior (under POSIX). Calling { io_service.stop(); } from a signal handler is not guaranteed to be safe.

Implementation suggestion

Declare and implement a public interface with the following semantics:

void io_service::async_stop(void);

/ Sets an internal flag in io_service to stop at the nearest event loop. May be called from a signal handler. */

Known workarounds

Let the io_service listen to a pipe. Write to the pipe from within the signal handler.

References

<URL:http://article.gmane.org/gmane.comp.lib.boost.user/58164>

[chris_kohlhoff]

Thanks for the suggestion, but I do not consider this the right approach for handling signals. The "correct" way would be to handle signals just like other asynchronous events. I will probably add this support at some point.

In the meantime, you could use a pipe (as you said), but you can also process the signals synchronously using sigwait(). All of the HTTP server examples take this approach.