RSS fixes (exponential back-off), handling feed errors with retries

include/libtorrent/rss.hpp

@@ -144,7 +144,7 @@ namespace libtorrent
 		void on_feed(error_code const& ec, http_parser const& parser
 			, char const* data, int size);
 	
-		void update_feed();
+		int update_feed();
 	
 		aux::session_impl& session() const { return m_ses; }
 	
@@ -186,6 +186,8 @@ namespace libtorrent
    	time_t m_last_update;
 		// refresh rate of this feed in minutes
 		int m_ttl;
+		// the number of update failures in a row
+		int m_failures;
 		// true while waiting for the server to respond
 		bool m_updating;
 		feed_settings m_settings;

src/rss.cpp

@@ -50,11 +50,13 @@ struct feed_state
 {
 	feed_state(feed& r)
 		: in_item(false)
+		, num_items(0)
 		, type(none)
 		, ret(r)
 	{}
 
 	bool in_item;
+	int num_items;
 	std::string current_tag;
 	enum feed_type
 	{
@@ -215,7 +217,10 @@ void parse_feed(feed_state& f, int token, char const* name, char const* val)
 				f.in_item = false;
 				if (!f.current_item.title.empty()
 					&& !f.current_item.url.empty())
+				{
 					f.ret.add_item(f.current_item);
+					++f.num_items;
+				}
 				f.current_item = feed_item();
 			}
 			f.current_tag = "";
@@ -263,7 +268,6 @@ void parse_feed(feed_state& f, int token, char const* name, char const* val)
 		case xml_declaration_tag: return;
 		case xml_comment: return;
 	}
-	
 }
 
 torrent_handle add_feed_item(session& s, feed_item const& fi
@@ -300,6 +304,7 @@ feed::feed(aux::session_impl& ses, feed_settings const& sett)
 	: m_last_attempt(0)
 	, m_last_update(0)
 	, m_ttl(-1)
+	, m_failures(0)
 	, m_updating(false)
 	, m_settings(sett)
 	, m_ses(ses)
@@ -330,6 +335,7 @@ void feed::on_feed(error_code const& ec
 
 	if (ec && ec != asio::error::eof)
 	{
+		++m_failures;
 		m_error = ec;
 		if (m_ses.m_alerts.should_post<rss_alert>())
 		{
@@ -341,6 +347,7 @@ void feed::on_feed(error_code const& ec
 
 	if (parser.status_code() != 200)
 	{
+		++m_failures;
 		m_error = error_code(parser.status_code(), get_http_category());
 		if (m_ses.m_alerts.should_post<rss_alert>())
 		{
@@ -350,6 +357,8 @@ void feed::on_feed(error_code const& ec
 		return;
 	}
 
+	m_failures = 0;
+
 	char* buf = const_cast<char*>(data);
 
 	feed_state s(*this);
@@ -392,7 +401,7 @@ void feed::on_feed(error_code const& ec
 	m_last_update = now;
 
 	// keep history of the typical feed size times 5
-	int max_history = (std::max)(int(m_items.size()) * 5, 100);
+	int max_history = (std::max)(s.num_items * 5, 100);
 
 	// this is not very efficient, but that's probably OK for now
 	while (int(m_added.size()) > max_history)
@@ -557,9 +566,10 @@ void feed::add_item(feed_item const& item)
 	m_items.push_back(item);
 }
 
-void feed::update_feed()
+// returns the number of seconds until trying again
+int feed::update_feed()
 {
-	if (m_updating) return;
+	if (m_updating) return 60;
 
 	m_last_attempt = time(0);
 	m_last_update = 0;
@@ -577,6 +587,8 @@ void feed::update_feed()
 
 	m_updating = true;
 	feed->get(m_settings.url, seconds(30), 0, 0, 5, m_ses.m_settings.user_agent);
+
+	return 60 + m_failures * m_failures * 60;
 }
 
 void feed::get_feed_status(feed_status* ret) const

src/session_impl.cpp

@@ -3880,10 +3880,8 @@ namespace aux {
 			feed& f = **i;
 			int delta = f.next_update(now_posix);
 			if (delta <= 0)
-			{
-				f.update_feed();
-				continue;
-			}
+				delta = f.update_feed();
+			TORRENT_ASSERT(delta >= 0);
 			ptime next_update = now + seconds(delta);
 			if (next_update < min_update) min_update = next_update;
 		}