added an active torrent limit

docs/manual.rst

@@ -2810,6 +2810,8 @@ that will be sent to the tracker. The user-agent is a good way to identify your
 
 		int active_downloads;
 		int active_seeds;
+		int active_limit;
+		bool dont_count_slow_torrents;
 		int auto_manage_interval;
 		float share_ratio_limit;
 		float seed_time_ratio_limit;
@@ -3036,6 +3038,14 @@ torrents active. Torrents that are not auto managed are also counted against the
 limits. If there are non-auto managed torrents that use up all the slots, no
 auto managed torrent will be activated.
 
+if ``dont_count_slow_torrents`` is true, torrents without any payload transfers are
+not subject to the ``active_seeds`` and ``active_downloads`` limits. This is intended
+to make it more likely to utilize all available bandwidth, and avoid having torrents
+that don't transfer anything block the active slots.
+
+``active_limit`` is a hard limit on the number of active seeds. This applies even to
+slow torrents.
+
 ``auto_manage_interval`` is the number of seconds between the torrent queue
 is updated, and rotated.
 

include/libtorrent/session_settings.hpp

@@ -126,7 +126,8 @@ namespace libtorrent
 			, peer_tos(0)
 			, active_downloads(8)
 			, active_seeds(5)
-			, dont_count_inactive_torrents(true)
+			, active_limit(15)
+			, dont_count_slow_torrents(true)
 			, auto_manage_interval(30)
 			, share_ratio_limit(2.f)
 			, seed_time_ratio_limit(7.f)
@@ -363,11 +364,12 @@ namespace libtorrent
 		// some slots free up.
 		int active_downloads;
 		int active_seeds;
+		int active_limit;
 
 		// if this is true, torrents that don't have any significant
 		// transfers are not counted as active when determining which
 		// auto managed torrents to pause and resume
-		bool dont_count_inactive_torrents;
+		bool dont_count_slow_torrents;
 
 		// the number of seconds in between recalculating which
 		// torrents to activate and which ones to queue

src/session_impl.cpp

@@ -1295,6 +1295,16 @@ namespace aux {
 		}
 	}
 
+	namespace
+	{
+		bool is_active(torrent* t, session_settings const& s)
+		{
+			return !(s.dont_count_slow_torrents
+				&& t->statistics().upload_payload_rate() == 0.f
+				&& t->statistics().download_payload_rate() == 0.f);
+		}
+	}
+
 	void session_impl::recalculate_auto_managed_torrents()
 	{
 		// these vectors are filled with auto managed torrents
@@ -1307,6 +1317,7 @@ namespace aux {
 		// of each kind we're allowed to have active
 		int num_downloaders = settings().active_downloads;
 		int num_seeds = settings().active_seeds;
+		int hard_limit = settings().active_limit;
 
         if (num_downloaders == -1)
             num_downloaders = (std::numeric_limits<int>::max)();
@@ -1329,11 +1340,15 @@ namespace aux {
 			}
 			else if (!t->is_paused())
 			{
-				// this is not an auto managed torrent,
-				// if it's running, decrease the respective
-				// counters.
-				--num_downloaders;
-				--num_seeds;
+				--hard_limit;
+			  	if (is_active(t, settings()))
+				{
+					// this is not an auto managed torrent,
+					// if it's running and active, decrease the
+					// counters.
+					--num_downloaders;
+					--num_seeds;
+				}
 			}
 		}
 
@@ -1357,14 +1372,15 @@ namespace aux {
 			, end(downloaders.end()); i != end; ++i)
 		{
 			torrent* t = *i;
-			if (!t->is_paused()
-				&& settings().dont_count_inactive_torrents
-				&& t->statistics().upload_payload_rate() == 0.f
-				&& t->statistics().download_payload_rate() == 0.f)
-				continue;
-
-			if (num_downloaders > 0)
+			if (!t->is_paused() && !is_active(t, settings()) && hard_limit > 0)
 			{
+				--hard_limit;
+				continue;
+			}
+
+			if (num_downloaders > 0 && hard_limit > 0)
+			{
+				--hard_limit;
 				if (t->state() != torrent_status::queued_for_checking
 					&& t->state() != torrent_status::checking_files)
 				{
@@ -1383,14 +1399,15 @@ namespace aux {
 			, end(seeds.end()); i != end; ++i)
 		{
 			torrent* t = *i;
-			if (!t->is_paused()
-				&& settings().dont_count_inactive_torrents
-				&& t->statistics().upload_payload_rate() == 0.f
-				&& t->statistics().download_payload_rate() == 0.f)
-				continue;
-
-			if (num_seeds > 0)
+			if (!t->is_paused() && !is_active(t, settings()) && hard_limit > 0)
 			{
+				--hard_limit;
+				continue;
+			}
+
+			if (num_seeds > 0 && hard_limit > 0)
+			{
+				--hard_limit;
 				--num_downloaders;
 				--num_seeds;
 				if (t->is_paused()) t->resume();