improve connect-boost feature, to make new torrents quickly connect peers

ChangeLog

@@ -1,3 +1,5 @@
+	* improve connect-boost feature, to make new torrents quickly connect peers
+
 1.1.9 release
 
 	* save both file and piece priorities in resume file

include/libtorrent/settings_pack.hpp

@@ -1408,6 +1408,7 @@ namespace libtorrent
 			// them starting up. The normal connect scheduler is run once every
 			// second, this allows peers to be connected immediately instead of
 			// waiting for the session tick to trigger connections.
+			// This may not be set higher than 255.
 			torrent_connect_boost,
 
 			// ``alert_queue_size`` is the maximum number of alerts queued up

include/libtorrent/torrent.hpp

@@ -1580,13 +1580,6 @@ namespace libtorrent
 		// work of refreshing the suggest pieces
 		bool m_need_suggest_pieces_refresh:1;
 
-		// this is set to true when the torrent starts up
-		// The first tracker response, when this is true,
-		// will attempt to connect to a bunch of peers immediately
-		// and set this to false. We only do this once to get
-		// the torrent kick-started
-		bool m_need_connect_boost:1;
-
 		// rotating sequence number for LSD announces sent out.
 		// used to only use IP broadcast for every 8th lsd announce
 		boost::uint8_t m_lsd_seq:3;
@@ -1610,7 +1603,14 @@ namespace libtorrent
 		// the number of bytes of padding files
 		boost::uint32_t m_padding:24;
 
-		// TODO: gap of 8 bits available here
+		// this is set to the connect boost quota for this torrent.
+		// After having received this many priority peer connection attempts, it
+		// falls back onto the steady state peer connection logic, driven by the
+		// session tick. Each tracker response, as long as this is non-zero, will
+		// attempt to connect to peers immediately and decrement the counter.
+		// We give torrents a connect boost when they are first added and then
+		// every time they resume from being paused.
+		boost::uint8_t m_connect_boost_counter;
 
 // ----
 

src/session_impl.cpp

@@ -4046,16 +4046,14 @@ retry:
 		// attempt this tick
 		int max_connections = m_settings.get_int(settings_pack::connection_speed);
 
-		// zero connections speeds are allowed, we just won't make any connections
-		if (max_connections <= 0) return;
-
 		// this loop will "hand out" connection_speed to the torrents, in a round
 		// robin fashion, so that every torrent is equally likely to connect to a
 		// peer
 
 		// boost connections are connections made by torrent connection
 		// boost, which are done immediately on a tracker response. These
-		// connections needs to be deducted from this second
+		// connections needs to be deducted from the regular connection attempt
+		// quota for this tick
 		if (m_boost_connections > 0)
 		{
 			if (m_boost_connections > max_connections)
@@ -4070,6 +4068,9 @@ retry:
 			}
 		}
 
+		// zero connections speeds are allowed, we just won't make any connections
+		if (max_connections <= 0) return;
+
 		// TODO: use a lower limit than m_settings.connections_limit
 		// to allocate the to 10% or so of connection slots for incoming
 		// connections

src/settings_pack.cpp

@@ -254,7 +254,7 @@ namespace libtorrent
 		SET(max_failcount, 3, &session_impl::update_max_failcount),
 		SET(min_reconnect_time, 60, 0),
 		SET(peer_connect_timeout, 15, 0),
-		SET(connection_speed, 10, &session_impl::update_connection_speed),
+		SET(connection_speed, 30, &session_impl::update_connection_speed),
 		SET(inactivity_timeout, 600, 0),
 		SET(unchoke_interval, 15, 0),
 		SET(optimistic_unchoke_interval, 30, 0),
@@ -334,7 +334,7 @@ namespace libtorrent
 		SET(utp_loss_multiplier, 50, 0),
 		SET(mixed_mode_algorithm, settings_pack::peer_proportional, 0),
 		SET(listen_queue_size, 5, 0),
-		SET(torrent_connect_boost, 10, 0),
+		SET(torrent_connect_boost, 80, 0),
 		SET(alert_queue_size, 1000, &session_impl::update_alert_queue_size),
 		SET(max_metadata_size, 3 * 1024 * 10240, 0),
 		DEPRECATED_SET(hashing_threads, 1, 0),

src/torrent.cpp

@@ -290,12 +290,12 @@ namespace libtorrent
 		, m_save_resume_flags(0)
 		, m_num_uploads(0)
 		, m_need_suggest_pieces_refresh(false)
-		, m_need_connect_boost(true)
 		, m_lsd_seq(0)
 		, m_magnet_link(false)
 		, m_apply_ip_filter((p.flags & add_torrent_params::flag_apply_ip_filter) != 0)
 		, m_merge_resume_trackers((p.flags & add_torrent_params::flag_merge_resume_trackers) != 0)
 		, m_padding(0)
+		, m_connect_boost_counter(static_cast<boost::uint8_t>(settings().get_int(settings_pack::torrent_connect_boost)))
 		, m_incomplete(0xffffff)
 		, m_announce_to_dht((p.flags & add_torrent_params::flag_paused) == 0)
 		, m_is_active_download(false)
@@ -3758,23 +3758,24 @@ namespace {
 
 	void torrent::do_connect_boost()
 	{
-		if (!m_need_connect_boost) return;
+		if (m_connect_boost_counter == 0) return;
 
 		// this is the first tracker response for this torrent
 		// instead of waiting one second for session_impl::on_tick()
 		// to be called, connect to a few peers immediately
-		int conns = (std::min)(
+		int conns = (std::min)(int(m_connect_boost_counter)
-			settings().get_int(settings_pack::torrent_connect_boost)
 			, settings().get_int(settings_pack::connections_limit) - m_ses.num_connections());
 
-		if (conns > 0) m_need_connect_boost = false;
+		if (conns == 0) return;
 
 		// if we don't know of any peers
 		if (!m_peer_list) return;
 
 		while (want_peers() && conns > 0)
 		{
+			TORRENT_ASSERT(m_connect_boost_counter > 0);
 			--conns;
+			--m_connect_boost_counter;
 			torrent_state st = get_peer_list_state();
 			torrent_peer* p = m_peer_list->connect_one_peer(m_ses.session_time(), &st);
 			peers_erased(st.erased);
@@ -9950,7 +9951,8 @@ namespace {
 		}
 #endif
 
-		m_need_connect_boost = true;
+		m_connect_boost_counter
+			= static_cast<boost::uint8_t>(settings().get_int(settings_pack::torrent_connect_boost));
 		m_inactive = false;
 
 		update_state_list();

src/ut_pex.cpp

@@ -337,6 +337,7 @@ namespace libtorrent { namespace
 			p = pex_msg.dict_find_string("added");
 			bdecode_node pf = pex_msg.dict_find_string("added.f");
 
+			bool peers_added = false;
 #ifndef TORRENT_DISABLE_LOGGING
 			if (p) num_added += p.string_length() / 6;
 #endif
@@ -363,6 +364,7 @@ namespace libtorrent { namespace
 					if (j != m_peers.end() && *j == v) continue;
 					m_peers.insert(j, v);
 					m_torrent.add_peer(adr, peer_info::pex, flags);
+					peers_added = true;
 				}
 			}
 
@@ -416,6 +418,7 @@ namespace libtorrent { namespace
 					if (j != m_peers6.end() && *j == v) continue;
 					m_peers6.insert(j, v);
 					m_torrent.add_peer(adr, peer_info::pex, flags);
+					peers_added = true;
 				}
 			}
 #endif
@@ -425,6 +428,8 @@ namespace libtorrent { namespace
 #endif
 
 			m_pc.stats_counters().inc_stats_counter(counters::num_incoming_pex);
+
+			if (peers_added) m_torrent.do_connect_boost();
 			return true;
 		}