add torrent priority to adjust bandwidth allocation of torrent's peers

ChangeLog

@@ -3,6 +3,7 @@
 
 0.15 release
 
+	* added torrent priority to affect bandwidth allocation for its peers
 	* reduced the number of floating point operations (to better support
 	  systems without FPU)
 	* added new alert when individual files complete

bindings/python/src/torrent_handle.cpp

@@ -313,6 +313,7 @@ void bind_torrent_handle()
         .def("pause", _(&torrent_handle::pause))
         .def("resume", _(&torrent_handle::resume))
         .def("clear_error", _(&torrent_handle::clear_error))
+        .def("set_priority", _(&torrent_handle::set_priority))
 
         .def("is_auto_managed", _(&torrent_handle::is_auto_managed))
         .def("auto_managed", _(&torrent_handle::auto_managed))

bindings/python/src/torrent_status.cpp

@@ -78,6 +78,7 @@ void bind_torrent_status()
         .def_readonly("seed_rank", &torrent_status::seed_rank)
         .def_readonly("last_scrape", &torrent_status::last_scrape)
         .def_readonly("error", &torrent_status::error)
+        .def_readonly("priority", &torrent_status::priority)
         ;
 
     enum_<torrent_status::state_t>("states")

docs/manual.rst

@@ -1893,6 +1893,8 @@ Its declaration looks like this::
 		void queue_position_top() const;
 		void queue_position_bottom() const;
 
+		void set_priority(int prio) const;
+
 		void use_interface(char const* net_interface) const;
 
 		void pause() const;
@@ -2508,6 +2510,25 @@ The ``queue_position_*()`` functions adjust the torrents position in the queue.
 closer to the front and down means closer to the back of the queue. Top and bottom refers
 to the front and the back of the queue respectively.
 
+set_priority()
+--------------
+
+	::
+
+		void set_priority(int prio) const;
+
+This sets the bandwidth priority of this torrent. The priority of a torrent determines
+how much bandwidth its peers are assigned when distributing upload and download rate quotas.
+A high number gives more bandwidth. The priority must be within the range [0, 255].
+
+The default priority is, which is the lowest priority.
+
+To query the priority of a torrent, use the `status()`_ call.
+
+Torrents with higher priority will not nececcarily get as much bandwidth as they can
+consume, even if there's is more quota. Other peers will still be weighed in when
+bandwidth is being distributed. With other words, bandwidth is not distributed strictly
+in order of priority, but the priority is used as a weight.
 
 use_interface()
 ---------------
@@ -2869,6 +2890,8 @@ It contains the following fields::
 		bool seed_mode;
 
 		bool upload_mode;
+
+		int priority;
 	};
 
 ``progress`` is a value in the range [0, 1], that represents the progress of the

include/libtorrent/bandwidth_queue_entry.hpp

@@ -77,7 +77,8 @@ struct bw_request
 		for (int j = 0; j < 5 && channel[j]; ++j)
 		{
 			if (channel[j]->throttle() == 0) continue;
-			quota = (std::min)(channel[j]->distribute_quota * priority / channel[j]->tmp, quota);
+			quota = (std::min)(int(boost::uint64_t(channel[j]->distribute_quota)
+				* priority / channel[j]->tmp), quota);
 		}
 		assigned += quota;
 		for (int j = 0; j < 5 && channel[j]; ++j)

include/libtorrent/peer_connection.hpp

@@ -228,6 +228,8 @@ namespace libtorrent
 		void set_priority(int p)
 		{
 			TORRENT_ASSERT(p > 0);
+			TORRENT_ASSERT(m_priority <= 255);
+			if (p > 255) p = 255;
 			m_priority = p;
 		}
 

include/libtorrent/torrent.hpp

@@ -286,6 +286,15 @@ namespace libtorrent
 		float ratio() const
 		{ return m_ratio; }
 
+		int priority() const { return m_priority; }
+		void set_priority(int prio)
+		{
+			TORRENT_ASSERT(prio <= 255 && prio >= 0);
+			if (prio > 255) prio = 255;
+			else if (prio < 0) prio = 0;
+			m_priority = prio;
+		}
+
 #ifndef TORRENT_DISABLE_RESOLVE_COUNTRIES
 		void resolve_countries(bool r)
 		{ m_resolve_countries = r; }
@@ -1015,6 +1024,11 @@ namespace libtorrent
 		// is called and the time scaler is reset to 10.
 		boost::int8_t m_time_scaler;
 
+		// this is the priority of the torrent. The higher
+		// the value is, the more bandwidth is assigned to
+		// the torrent's peers
+		boost::uint8_t m_priority;
+
 		// is set to true when the torrent has
 		// been aborted.
 		bool m_abort:1;

include/libtorrent/torrent_handle.hpp

@@ -118,6 +118,8 @@ namespace libtorrent
 			, has_incoming(false)
 			, sparse_regions(0)
 			, seed_mode(false)
+			, upload_mode(false)
+			, priority(0)
 		{}
 
 		enum state_t
@@ -293,6 +295,9 @@ namespace libtorrent
 		// from downloading, typically caused by a file
 		// write operation failing
 		bool upload_mode;
+
+		// the priority of this torrent
+		int priority;
 	};
 
 	struct TORRENT_EXPORT block_info
@@ -385,6 +390,8 @@ namespace libtorrent
 		enum deadline_flags { alert_when_available = 1 };
 		void set_piece_deadline(int index, time_duration deadline, int flags = 0) const;
 
+		void set_priority(int prio) const;
+		
 #ifndef TORRENT_NO_DEPRECATE
 #if !TORRENT_NO_FPU
 		// fills the specified vector with the download progress [0, 1]

src/peer_connection.cpp

@@ -3877,6 +3877,10 @@ namespace libtorrent
 	{
 		shared_ptr<torrent> t = m_torrent.lock();
 		int priority = 1 + is_interesting() * 2 + m_requests_in_buffer.size();
+
+		if (priority > 255) priority = 255;
+		priority += t->priority() << 8;
+
 		// peers that we are not interested in are non-prioritized
 		m_channel_state[upload_channel] = peer_info::bw_limit;
 		m_ses.m_upload_rate.request_bandwidth(self()
@@ -3905,12 +3909,15 @@ namespace libtorrent
 			"download: " << (m_download_queue.size() * 16 * 1024 + 30)
 			<< " prio: " << m_priority << " ]\n";
 #endif
+		TORRENT_ASSERT(m_priority <= 255);
+		int priority = m_priority + (t->priority() << 8);
+
 		TORRENT_ASSERT(m_channel_state[download_channel] == peer_info::bw_idle
 			|| m_channel_state[download_channel] == peer_info::bw_disk);
 		TORRENT_ASSERT(m_outstanding_bytes >= 0);
 		m_channel_state[download_channel] = peer_info::bw_limit;
 		m_ses.m_download_rate.request_bandwidth(self()
-			, m_outstanding_bytes + 30, m_priority
+			, m_outstanding_bytes + 30, priority
 			, bwc1, bwc2, bwc3, bwc4);
 	}
 

src/torrent.cpp

@@ -5761,6 +5761,7 @@ namespace libtorrent
 		st.upload_mode = m_upload_mode;
 		st.up_bandwidth_queue = 0;
 		st.down_bandwidth_queue = 0;
+		st.priority = m_priority;
 
 		st.num_peers = (int)std::count_if(m_connections.begin(), m_connections.end()
 			, !boost::bind(&peer_connection::is_connecting, _1));

src/torrent_handle.cpp

@@ -326,6 +326,12 @@ namespace libtorrent
 		TORRENT_FORWARD(auto_managed(m));
 	}
 
+	void torrent_handle::set_priority(int p) const
+	{
+		INVARIANT_CHECK;
+		TORRENT_FORWARD(set_priority(p));
+	}
+
 	int torrent_handle::queue_position() const
 	{
 		INVARIANT_CHECK;