How to break out libevent's dispatch loop

I've implemented a tiny webserver in a separate thread using the nice libevent library. The webserver runs event_base_dispatch() to process all events. What I need is a way to break out this dispatch loop from the main thread.

It boils down to the following C++ code:

#include <stdlib.h>
#include <signal.h>
#include <thread>
#include <evhttp.h>

struct event_base *eb;
std::thread t;

static volatile sig_atomic_t bailout = false;

void my_signal_handler(int) {
    bailout = true;
}

void onRequest(evhttp_request *req, void *) {
    struct evbuffer *OutBuf = evhttp_request_get_output_buffer(req);
    evbuffer_add_printf(OutBuf, "<html><body>Testing 1-2-3</body></html>");
    evhttp_send_reply(req, HTTP_OK, "OK", OutBuf);
}

void dispatch() {
    eb = event_base_new();
    struct evhttp *http = evhttp_new(eb);
    evhttp_set_gencb(http, &onRequest, NULL);
    evhttp_bind_socket_with_handle(http, "0.0.0.0", 5555);
    event_base_dispatch(eb);
}

int main() {

    struct sigaction sigIntHandler;
    sigIntHandler.sa_handler = my_signal_handler;
    sigemptyset(&sigIntHandler.sa_mask);
    sigIntHandler.sa_flags = 0;
    sigaction(SIGINT, &sigIntHandler, NULL);

    t = std::thread { &dispatch };

    while ( ! bailout ) {
        std::this_thread::sleep_for(std::chrono::seconds(1));
    }

    event_base_loopexit(eb, NULL);

    t.join();
}

The behavior is that if you run the program, request a page, abort the program by Ctrl-C, the event_base_dispatch() keeps running until you fetch another web page. Only then the loop aborts and the program terminates.

Solution

If you need the event loop to exit before running any more callbacks, use event_base_break()

http://www.wangafu.net/~nickm/libevent-book/Ref3_eventloop.html#_stopping_the_loop