From 3d759e893663449f9f0937b095f71e0561f04a98 Mon Sep 17 00:00:00 2001
From: Arvid Norberg <arvid@libtorrent.org>
Date: Fri, 13 Apr 2007 17:47:40 +0000
Subject: [PATCH] fixes in connection policy. fixes #29. inserted more
 invariant checks in policy

---
 include/libtorrent/policy.hpp | 16 --------------
 src/peer_connection.cpp       |  9 ++------
 src/policy.cpp                | 39 +++++++++++++++++++++++++++++------
 3 files changed, 35 insertions(+), 29 deletions(-)

diff --git a/include/libtorrent/policy.hpp b/include/libtorrent/policy.hpp
index 918f4ee83..ff4ad47e6 100755
--- a/include/libtorrent/policy.hpp
+++ b/include/libtorrent/policy.hpp
@@ -208,22 +208,6 @@ namespace libtorrent
 		iterator find_disconnect_candidate();
 		iterator find_connect_candidate();
 
-		// a functor that identifies peers that have disconnected and that
-		// are too old for still being saved.
-		struct old_disconnected_peer
-		{
-			bool operator()(const peer& p)
-			{
-				ptime not_tried_yet(min_time());
-
-				// this timeout has to be customizable!
-				return p.connection == 0
-					&& p.connected != not_tried_yet
-					&& time_now() - p.connected > minutes(120);
-			}
-		};
-
-
 		std::list<peer> m_peers;
 
 		torrent* m_torrent;
diff --git a/src/peer_connection.cpp b/src/peer_connection.cpp
index 02c8fde21..8888f5ca5 100755
--- a/src/peer_connection.cpp
+++ b/src/peer_connection.cpp
@@ -233,13 +233,8 @@ namespace libtorrent
 			else
 				t->get_policy().peer_is_interesting(*this);
 		}
-		catch (std::exception& e)
-		{
-#ifndef NDEBUG
-			std::cerr << e.what() << std::endl;
-			assert(false);
-#endif
-		}
+		// may throw an asio error if socket has disconnected
+		catch (std::exception& e) {}
 
 		assert(is_interesting() == interested);
 	}
diff --git a/src/policy.cpp b/src/policy.cpp
index d25585042..a03aa974f 100755
--- a/src/policy.cpp
+++ b/src/policy.cpp
@@ -462,6 +462,8 @@ namespace libtorrent
 
 	policy::iterator policy::find_disconnect_candidate()
 	{
+		INVARIANT_CHECK;
+
 		iterator disconnect_peer = m_peers.end();
 		double slowest_transfer_rate = std::numeric_limits<double>::max();
 
@@ -491,7 +493,11 @@ namespace libtorrent
 			double transfer_rate
 				= transferred_amount / (connected_time_in_seconds + 1);
 
-			if (transfer_rate <= slowest_transfer_rate)
+			// prefer to disconnect uninteresting peers, and secondly slow peers
+			if (transfer_rate <= slowest_transfer_rate
+				|| (disconnect_peer != m_peers.end()
+				&& disconnect_peer->connection->is_interesting()
+				&& !c->is_interesting()))
 			{
 				slowest_transfer_rate = transfer_rate;
 				disconnect_peer = i;
@@ -502,6 +508,8 @@ namespace libtorrent
 
 	policy::iterator policy::find_connect_candidate()
 	{
+		INVARIANT_CHECK;
+
 		ptime now = time_now();
 		ptime ptime(now);
 		iterator candidate = m_peers.end();
@@ -646,11 +654,20 @@ namespace libtorrent
 		if (m_torrent->is_paused()) return;
 
 		// remove old disconnected peers from the list
-		m_peers.erase(
-			std::remove_if(m_peers.begin()
-				, m_peers.end()
-				, old_disconnected_peer())
-			, m_peers.end());
+		for (iterator i = m_peers.begin(); i != m_peers.end();)
+		{
+			// this timeout has to be customizable!
+			if (i->connection == 0
+				&& i->connected != min_time()
+				&& time_now() - i->connected > minutes(120))
+			{
+				m_peers.erase(i++);
+			}
+			else
+			{
+				++i;
+			}
+		}
 
 		// -------------------------------------
 		// maintain the number of connections
@@ -1131,6 +1148,8 @@ namespace libtorrent
 
 	bool policy::unchoke_one_peer()
 	{
+		INVARIANT_CHECK;
+
 		iterator p = find_unchoke_candidate();
 		if (p == m_peers.end()) return false;
 		assert(p->connection);
@@ -1145,6 +1164,8 @@ namespace libtorrent
 
 	void policy::choke_one_peer()
 	{
+		INVARIANT_CHECK;
+
 		iterator p = find_choke_candidate();
 		if (p == m_peers.end()) return;
 		assert(p->connection);
@@ -1156,6 +1177,8 @@ namespace libtorrent
 
 	bool policy::connect_one_peer()
 	{
+		INVARIANT_CHECK;
+
 		if(m_torrent->num_peers() >= m_torrent->m_connections_quota.given)
 			return false;
 		
@@ -1288,6 +1311,8 @@ namespace libtorrent
 #ifndef NDEBUG
 	bool policy::has_connection(const peer_connection* c)
 	{
+		INVARIANT_CHECK;
+
 		assert(c);
 		assert((c->proxy() == tcp::endpoint() && c->remote() == c->get_socket()->remote_endpoint())
 			|| c->proxy() == c->get_socket()->remote_endpoint());
@@ -1313,6 +1338,8 @@ namespace libtorrent
 		{
 			++total_connections;
 			if (!i->connection) continue;
+			assert(i->connection->peer_info_struct() == 0
+				|| i->connection->peer_info_struct() == &*i);
 			++nonempty_connections;
 			if (!i->connection->is_disconnecting())
 				++connected_peers;