merged RC_1_1 into master

ChangeLog

@@ -73,6 +73,7 @@
 	* require C++11 to build libtorrent
 
 
+	* improve shutdown time by only announcing to trackers whose IP we know
 	* fix python3 portability issue in python binding
 	* delay 5 seconds before reconnecting socks5 proxy for UDP ASSOCIATE
 	* fix NAT-PMP crash when removing a mapping at the wrong time

docs/manual.rst

@@ -184,6 +184,19 @@ The format of the magnet URI is:
 
 **magnet:?xt=urn:btih:** *Base16 encoded info-hash* [ **&dn=** *name of download* ] [ **&tr=** *tracker URL* ]*
 
+In order to download *just* the metadata (.torrent file) from a magnet link, set
+file priorities to 0 in add_torrent_params::file_priorities. It's OK to set the
+priority for more files than what is in the torrent. It may not be trivial to
+know how many files a torrent has before the metadata has been downloaded.
+Additional file priorities will be ignored. By setting a large number of files
+to priority 0, chances are that they will all be set to 0 once the metadata is
+received (and we know how many files there are).
+
+In this case, when the metadata is received from the swarm, the torrent will
+still be running, but it will disconnect the majority of peers (since connections
+to peers that already have the metadata are redundant). It will keep seeding the
+*metadata* only.
+
 queuing
 =======
 
@@ -261,9 +274,25 @@ Once a torrent completes checking and moves into a diffferent state, the next in
 line will be started for checking.
 
 Any torrent added force-started or force-stopped (i.e. the auto managed flag is
-_not_ set), will not be subject to this limit and they will all check
+*not* set), will not be subject to this limit and they will all check
 independently and in parallel.
 
+Once a torrent completes the checking of its files, or fastresume data, it will
+be put in the queue for downloading and potentially start downloading immediately.
+In order to add a torrent and check its files without starting the download, it
+can be added in ``stop_when_ready`` mode.
+See add_torrent_params::flag_stop_when_ready. This flag will stop the torrent
+once it is ready to start downloading.
+
+This is conceptually the same as waiting for the ``torrent_checked_alert`` and
+then call::
+
+	h.auto_managed(false);
+	h.pause();
+
+With the important distinction that it entirely avoids the brief window where
+the torrent is in downloading state.
+
 downloading queue
 -----------------
 

include/libtorrent/resolver_interface.hpp

@@ -48,10 +48,11 @@ struct TORRENT_EXTRA_EXPORT resolver_interface
 
 	enum flags_t
 	{
-		// this flag will make async_resolve() always use the cache if we have an
-		// entry, regardless of how old it is. This is useful when completing the
-		// lookup quickly is more important than accuracy
-		prefer_cache = 1,
+		// this flag will make async_resolve() only use the cache and fail if we
+		// don't have a cache entry, regardless of how old it is. This is usefull
+		// when completing the lookup quickly is more important than accuracy,
+		// like on shutdown
+		cache_only = 1,
 
 		// set this flag for lookups that are not critical during shutdown. i.e.
 		// for looking up tracker names _except_ when stopping a tracker.

src/http_tracker_connection.cpp

@@ -224,8 +224,8 @@ namespace libtorrent {
 			, ps.proxy_tracker_connections ? &ps : nullptr
 			, 5, user_agent, bind_interface()
 			, tracker_req().event == tracker_request::stopped
-				? resolver_interface::prefer_cache
-				: resolver_interface::abort_on_shutdown
+				? resolver_interface::cache_only : 0
+				| resolver_interface::abort_on_shutdown
 #ifndef TORRENT_NO_DEPRECATE
 			, tracker_req().auth
 #else

src/resolver.cpp

@@ -86,19 +86,6 @@ namespace libtorrent {
 	void resolver::async_resolve(std::string const& host, int const flags
 		, resolver_interface::callback_t const& h)
 	{
-		auto const i = m_cache.find(host);
-		if (i != m_cache.end())
-		{
-			// keep cache entries valid for m_timeout seconds
-			if ((flags & resolver_interface::prefer_cache)
-				|| i->second.last_seen + m_timeout >= aux::time_now())
-			{
-				error_code ec;
-				m_ios.post(std::bind(h, ec, i->second.addresses));
-				return;
-			}
-		}
-
 		// special handling for raw IP addresses. There's no need to get in line
 		// behind actual lookups if we can just resolve it immediately.
 		error_code ec;
@@ -110,6 +97,27 @@ namespace libtorrent {
 			m_ios.post(std::bind(h, ec, addresses));
 			return;
 		}
+		ec.clear();
+
+		auto const i = m_cache.find(host);
+		if (i != m_cache.end())
+		{
+			// keep cache entries valid for m_timeout seconds
+			if ((flags & resolver_interface::cache_only)
+				|| i->second.last_seen + m_timeout >= aux::time_now())
+			{
+				m_ios.post(std::bind(h, ec, i->second.addresses));
+				return;
+			}
+		}
+
+		if (flags & resolver_interface::cache_only)
+		{
+			// we did not find a cache entry, fail the lookup
+			m_ios.post(std::bind(h, boost::asio::error::host_not_found
+					, std::vector<address>()));
+			return;
+		}
 
 		// the port is ignored
 		tcp::resolver::query const q(host, "80");

src/udp_tracker_connection.cpp

@@ -103,13 +103,12 @@ namespace libtorrent {
 		{
 			using namespace std::placeholders;
 			ADD_OUTSTANDING_ASYNC("udp_tracker_connection::name_lookup");
-			// when stopping, pass in the prefer cache flag, because we
+			// when stopping, pass in the cache-only flag, because we
 			// don't want to get stuck on DNS lookups when shutting down
-			// if we can avoid it
 			m_man.host_resolver().async_resolve(hostname
 				, tracker_req().event == tracker_request::stopped
-					? resolver_interface::prefer_cache
-					: resolver_interface::abort_on_shutdown
+					? resolver_interface::cache_only : 0
+					| resolver_interface::abort_on_shutdown
 				, std::bind(&udp_tracker_connection::name_lookup
 					, shared_from_this(), _1, _2, port));