changed the optimistic disconnect logic to be more efficient and configurable

include/libtorrent/peer_connection.hpp

@@ -242,6 +242,9 @@ namespace libtorrent
 		std::vector<int> const& allowed_fast();
 		std::vector<int> const& suggested_pieces() const { return m_suggested_pieces; }
 
+		ptime connected_time() const { return m_connect; }
+		ptime last_received() const { return m_last_receive; }
+
 		void timed_out();
 		// this will cause this peer_connection to be disconnected.
 		void disconnect(char const* message);

include/libtorrent/policy.hpp

@@ -248,7 +248,6 @@ namespace libtorrent
 		const_iterator end_peer() const { return m_peers.end(); }
 
 		bool connect_one_peer();
-		bool disconnect_one_peer();
 
 		bool has_peer(policy::peer const* p) const;
 
@@ -267,7 +266,6 @@ namespace libtorrent
 		bool compare_peer(policy::peer const& lhs, policy::peer const& rhs
 			, address const& external_ip) const;
 
-		iterator find_disconnect_candidate();
 		iterator find_connect_candidate();
 
 		bool is_connect_candidate(peer const& p, bool finished);

include/libtorrent/session_settings.hpp

@@ -102,11 +102,7 @@ namespace libtorrent
 			, min_reconnect_time(60)
 			, peer_connect_timeout(7)
 			, ignore_limits_on_local_network(true)
-#if !defined NDEBUG && !defined TORRENT_DISABLE_INVARIANT_CHECKS
-			, connection_speed(2)
-#else
 			, connection_speed(20)
-#endif
 			, send_redundant_have(false)
 			, lazy_bitfields(true)
 			, inactivity_timeout(600)
@@ -134,6 +130,9 @@ namespace libtorrent
 			, share_ratio_limit(2.f)
 			, seed_time_ratio_limit(7.f)
 			, seed_time_limit(24 * 60 * 60) // 24 hours
+			, peer_turnover(1 / 50.f)
+			, peer_turnover_cutoff(1.f)
+			, close_redundant_connections(true)
 		{}
 
 		// this is the user agent that will be sent to the tracker
@@ -376,6 +375,23 @@ namespace libtorrent
 		float share_ratio_limit;
 		float seed_time_ratio_limit;
 		int seed_time_limit;
+
+		// the percentage of peers to disconnect every
+		// 90 seconds (if we're at the peer limit)
+		// defaults to 1/50:th
+		float peer_turnover;
+
+		// when we are connected to more than
+		// limit * peer_turnover_enable peers
+		// disconnect peer_turnover fraction
+		// of the peers
+		float peer_turnover_cutoff;
+
+		// if this is true (default) connections where both
+		// ends have no utility in keeping the connection open
+		// are closed. for instance if both ends have completed
+		// their downloads
+		bool close_redundant_connections;
 	};
 
 #ifndef TORRENT_DISABLE_DHT

include/libtorrent/torrent.hpp

@@ -452,6 +452,7 @@ namespace libtorrent
 		void announce_piece(int index);
 
 		void disconnect_all();
+		int disconnect_peers(int num);
 
 		// this is called wheh the torrent has completed
 		// the download. It will post an event, disconnect