added rtt estimation for outgoing connections

docs/manual.html

@@ -2339,6 +2339,8 @@ struct peer_info
 
         int send_quota;
         int receive_quota;
+
+        int rtt;
 };
 </pre>
 <p>The <tt class="docutils literal"><span class="pre">flags</span></tt> attribute tells you in which state the peer is. It is set to
@@ -2546,6 +2548,8 @@ is capped by <tt class="docutils literal"><span class="pre">session_settings::ma
 <p><tt class="docutils literal"><span class="pre">send_quota</span></tt> and <tt class="docutils literal"><span class="pre">receive_quota</span></tt> are the number of bytes this peer has been
 assigned to be allowed to send and receive until it has to request more quota
 from the bandwidth manager.</p>
+<p><tt class="docutils literal"><span class="pre">rtt</span></tt> is an estimated round trip time to this peer, in milliseconds. It is
+estimated by timing the the tcp <tt class="docutils literal"><span class="pre">connect()</span></tt>. It may be 0 for incoming connections.</p>
 </div>
 <div class="section">
 <h1><a id="session-settings" name="session-settings">session_settings</a></h1>

docs/manual.rst

@@ -2332,6 +2332,8 @@ It contains the following fields::
 
 		int send_quota;
 		int receive_quota;
+
+		int rtt;
 	};
 
 The ``flags`` attribute tells you in which state the peer is. It is set to
@@ -2531,6 +2533,10 @@ is capped by ``session_settings::max_outstanding_disk_bytes_per_connection``.
 assigned to be allowed to send and receive until it has to request more quota
 from the bandwidth manager.
 
+``rtt`` is an estimated round trip time to this peer, in milliseconds. It is
+estimated by timing the the tcp ``connect()``. It may be 0 for incoming connections.
+
+
 session_settings
 ================
 

examples/client_test.cpp

@@ -321,7 +321,7 @@ int peer_index(libtorrent::tcp::endpoint addr, std::vector<libtorrent::peer_info
 void print_peer_info(std::ostream& out, std::vector<libtorrent::peer_info> const& peers)
 {
 	using namespace libtorrent;
-	out << "IP                      down    (total)   up      (total)  sent-req recv flags        source fail hshf sndb         inactive wait disk quota block-progress "
+	out << "IP                      down    (total)   up      (total)  sent-req recv flags        source fail hshf sndb         inactive wait disk  quota  rtt block-progress "
 #ifndef TORRENT_DISABLE_RESOLVE_COUNTRIES
 		"country "
 #endif
@@ -379,12 +379,13 @@ void print_peer_info(std::ostream& out, std::vector<libtorrent::peer_info> const
 			<< to_string(total_seconds(i->last_active), 8) << " "
 			<< to_string(total_seconds(i->last_request), 4) << " "
 			<< add_suffix(i->pending_disk_bytes) << " "
-			<< to_string(i->send_quota, 5) << " ";
+			<< to_string(i->send_quota, 5) << " "
+			<< to_string(i->rtt, 4) << " ";
 
 		if (i->downloading_piece_index >= 0)
 		{
 			out << progress_bar(
-				i->downloading_progress / float(i->downloading_total), 15);
+				i->downloading_progress / float(i->downloading_total), 14);
 		}
 		else
 		{

include/libtorrent/peer_connection.hpp

@@ -742,6 +742,14 @@ namespace libtorrent
 		// immediate.
 		bool m_fast_reconnect;
 		
+		// the time when async_connect was called
+		ptime m_connect;
+
+		// estimated round trip time to this peer
+		// based on the time from when async_connect
+		// was called to when on_connection_complete
+		// was called. The rtt is specified in milliseconds
+		int m_rtt;
 #ifndef NDEBUG
 	public:
 		bool m_in_constructor;

include/libtorrent/peer_info.hpp

@@ -171,6 +171,9 @@ namespace libtorrent
 		// numbers used for bandwidth limiting
 		int send_quota;
 		int receive_quota;
+
+		// estimated rtt to peer, in milliseconds
+		int rtt;
 	};
 
 }

src/peer_connection.cpp

@@ -118,6 +118,7 @@ namespace libtorrent
 		, m_remote_dl_update(time_now())
 		, m_outstanding_writing_bytes(0)
 		, m_fast_reconnect(false)
+		, m_rtt(0)
 #ifndef NDEBUG
 		, m_in_constructor(true)
 #endif
@@ -200,6 +201,7 @@ namespace libtorrent
 		, m_remote_dl_update(time_now())
 		, m_outstanding_writing_bytes(0)
 		, m_fast_reconnect(false)
+		, m_rtt(0)
 #ifndef NDEBUG
 		, m_in_constructor(true)
 #endif
@@ -2162,6 +2164,7 @@ namespace libtorrent
 	{
 		TORRENT_ASSERT(!associated_torrent().expired());
 
+		p.rtt = m_rtt;
 		p.down_speed = statistics().download_rate();
 		p.up_speed = statistics().upload_rate();
 		p.payload_down_speed = statistics().download_payload_rate();
@@ -2912,6 +2915,7 @@ namespace libtorrent
 		}
 		m_socket->async_connect(m_remote
 			, bind(&peer_connection::on_connection_complete, self(), _1));
+		m_connect = time_now();
 
 		if (t->alerts().should_post(alert::debug))
 		{
@@ -2922,10 +2926,14 @@ namespace libtorrent
 	
 	void peer_connection::on_connection_complete(asio::error_code const& e) try
 	{
+		ptime completed = time_now();
+
 		session_impl::mutex_t::scoped_lock l(m_ses.m_mutex);
 
 		INVARIANT_CHECK;
 
+		m_rtt = total_milliseconds(completed - m_connect);
+		
 		if (m_disconnecting) return;
 
 		m_connecting = false;
@@ -2948,7 +2956,8 @@ namespace libtorrent
 		// this means the connection just succeeded
 
 #if defined TORRENT_VERBOSE_LOGGING || defined TORRENT_LOGGING
-		(*m_ses.m_logger) << time_now_string() << " COMPLETED: " << m_remote.address().to_string() << "\n";
+		(*m_ses.m_logger) << time_now_string() << " COMPLETED: " << m_remote.address().to_string()
+			<< " rtt = " << m_rtt << "\n";
 #endif
 
 		on_connected();