asio handlers are now properly cancelled when destructing the session object, race conditions are avoided by waiting for the io service to complete all tasks

src/udp_tracker_connection.cpp

@@ -96,7 +96,9 @@ namespace libtorrent
 		m_name_lookup.async_resolve(q
 			, m_strand.wrap(boost::bind(
 			&udp_tracker_connection::name_lookup, self(), _1, _2)));
-		set_timeout(m_settings.tracker_completion_timeout
+		set_timeout(req.event == tracker_request::stopped
+			? m_settings.stop_tracker_timeout
+			: m_settings.tracker_completion_timeout
 			, m_settings.tracker_receive_timeout);
 	}
 
@@ -156,11 +158,20 @@ namespace libtorrent
 
 	void udp_tracker_connection::on_timeout()
 	{
-		m_socket.close();
+		asio::error_code ec;
+		m_socket.close(ec);
 		m_name_lookup.cancel();
 		fail_timeout();
 	}
 
+	void udp_tracker_connection::close()
+	{
+		asio::error_code ec;
+		m_socket.close(ec);
+		m_name_lookup.cancel();
+		tracker_connection::close();
+	}
+
 	void udp_tracker_connection::send_udp_connect()
 	{
 #if defined(TORRENT_VERBOSE_LOGGING) || defined(TORRENT_LOGGING)
@@ -468,6 +479,7 @@ namespace libtorrent
 			, complete, incomplete);
 
 		m_man.remove_request(this);
+		close();
 		return;
 	}
 	catch (std::exception& e)
@@ -543,6 +555,7 @@ namespace libtorrent
 		if (!cb)
 		{
 			m_man.remove_request(this);
+			close();
 			return;
 		}
 		
@@ -551,6 +564,7 @@ namespace libtorrent
 			, complete, incomplete);
 
 		m_man.remove_request(this);
+		close();
 	}
 	catch (std::exception& e)
 	{