Boost.Asio segfault, no idea why - c++

Question

This is a SSCCE from my Boost.Asio project based on the examples. It took me about an hour to track the bug down to this:
#include <boost/bind.hpp>
#include <boost/asio.hpp>
#include <boost/shared_ptr.hpp>
class Connection {
public:
Connection(boost::asio::io_service& io_service) : socket(io_service) {}
private:
boost::asio::ip::tcp::socket socket;
};
class Server {
public:
Server() : signal_monitor(io_service) {
signal_monitor.add(SIGINT);
signal_monitor.add(SIGTERM);
signal_monitor.async_wait(
boost::bind(&Server::handle_signal_caught, this)
);
}
void run() {
// comment out the next line and there's no segfault
connection.reset(new Connection(io_service));
io_service.run();
}
private:
void handle_signal_caught() {
io_service.stop();
}
boost::shared_ptr<Connection> connection;
boost::asio::io_service io_service;
boost::asio::signal_set signal_monitor;
};
int main(int argc, char **argv) {
Server server;
server.run();
return 0;
}
When I send a signal (ctrl+C) the program segfaults instead of shutting down nicely. I've spent the last half hour looking at this, but I simply do not see why this would segfault, can any of you guys spot the issue?

Answer 1

I think I found out the issue. Note the declaration order of the members of Server:
boost::shared_ptr<Connection> connection;
boost::asio::io_service io_service;
boost::asio::signal_set signal_monitor;
Destruction order is done in the opposite order of declaration. This means that first signal_monitor, then io_service and finally connection get destroyed. But connection contains a boost::asio::ip::tcp::socket containing a reference to io_service, which got destroyed.
And indeed, this is pretty much what happening, and causes a segfault too:
int main(int argc, char **argv) {
auto io_service = new boost::asio::io_service();
auto socket = new boost::asio::ip::tcp::socket(*io_service);
delete io_service;
delete socket;
return 0;
}
Declaring connection after io_service solves the issue.
Damn