optimize peer classes a bit

include/libtorrent/peer_class.hpp

@@ -44,38 +44,40 @@ POSSIBILITY OF SUCH DAMAGE.
 
 namespace libtorrent
 {
-	typedef boost::uint32_t peer_class_t;
+	typedef boost::uint8_t peer_class_t;
 
 	struct peer_class_info
 	{
-		// ``ignore_unchoke_slots`` determines whether peers should always unchoke a peer,
-		// regardless of the choking algorithm, or if it should honor the unchoke slot limits.
-		// It's used for local peers by default. If *any* of the peer classes a peer belongs to
-		// has this set to true, that peer will be unchoked at all times.
+		// ``ignore_unchoke_slots`` determines whether peers should always
+		// unchoke a peer, regardless of the choking algorithm, or if it should
+		// honor the unchoke slot limits. It's used for local peers by default.
+		// If *any* of the peer classes a peer belongs to has this set to true,
+		// that peer will be unchoked at all times.
 		bool ignore_unchoke_slots;
 
-		// adjusts the connection limit (global and per torrent) that
-		// applies to this peer class. By default, local peers are allowed to exceed the normal
-		// connection limit for instance. This is specified as a percent factor. 100 makes
-		// the peer class apply normally to the limit. 200 means as long as there are fewer
-		// connections than twice the limit, we accept this peer. This factor applies both to
-		// the global connection limit and the per-torrent limit. Note that if not used carefully
-		// one peer class can potentially completely starve out all other over time.
+		// adjusts the connection limit (global and per torrent) that applies to
+		// this peer class. By default, local peers are allowed to exceed the
+		// normal connection limit for instance. This is specified as a percent
+		// factor. 100 makes the peer class apply normally to the limit. 200
+		// means as long as there are fewer connections than twice the limit, we
+		// accept this peer. This factor applies both to the global connection
+		// limit and the per-torrent limit. Note that if not used carefully one
+		// peer class can potentially completely starve out all other over time.
 		int connection_limit_factor;
 
-		// not used by libtorrent. It's intended as a potentially user-facing identifier
-		// of this peer class.
+		// not used by libtorrent. It's intended as a potentially user-facing
+		// identifier of this peer class.
 		std::string label;
 
-		// transfer rates limits for the whole peer class.
-		// They are specified in bytes per second and apply to the sum of all peers that are
-		// members of this class.
+		// transfer rates limits for the whole peer class. They are specified in
+		// bytes per second and apply to the sum of all peers that are members of
+		// this class.
 		int upload_limit;
 		int download_limit;
 
-		// relative priorities used by the
-		// bandwidth allocator in the rate limiter. If no rate limits are in use, the priority
-		// is not used either. Priorities start at 1 (0 is not a valid priority) and may not
+		// relative priorities used by the bandwidth allocator in the rate
+		// limiter. If no rate limits are in use, the priority is not used
+		// either. Priorities start at 1 (0 is not a valid priority) and may not
 		// exceed 255.
 		int upload_priority;
 		int download_priority;
@@ -137,7 +139,7 @@ namespace libtorrent
 		std::vector<boost::intrusive_ptr<peer_class> > m_peer_classes;
 
 		// indices in m_peer_classes that are no longer used
-		std::vector<int> m_free_list;
+		std::vector<peer_class_t> m_free_list;
 	};
 }
 

include/libtorrent/peer_class_set.hpp

@@ -34,7 +34,7 @@ POSSIBILITY OF SUCH DAMAGE.
 #define TORRENT_PEER_CLASS_SET_HPP_INCLUDED
 
 #include "libtorrent/peer_class.hpp"
-#include <vector>
+#include <boost/array.hpp>
 
 namespace libtorrent {
 
@@ -42,24 +42,27 @@ namespace libtorrent {
 	// to it. Most notably, peer connections and torrents derive from this.
 	struct peer_class_set
 	{
+		peer_class_set() : m_size(0) {}
 		void add_class(peer_class_pool& pool, peer_class_t c);
 		bool has_class(peer_class_t c) const;
 		void remove_class(peer_class_pool& pool, peer_class_t c);
-		int num_classes() const { return m_class.size(); }
+		int num_classes() const { return m_size; }
 		peer_class_t class_at(int i) const
 		{
-			TORRENT_ASSERT(i >= 0 && i < int(m_class.size()));
+			TORRENT_ASSERT(i >= 0 && i < int(m_size));
 			return m_class[i];
 		}
 
 	private:
 
-		// if this object belongs to any peer-class, this
-		// vector contains all class IDs. Each ID refers
-		// to a an entry in m_ses.m_peer_classes which
-		// holds the metadata about the class. Classes
-		// affect bandwidth limits among other things
-		std::vector<peer_class_t> m_class;
+		// the number of elements used in the m_class array
+		boost::uint8_t m_size;
+
+		// if this object belongs to any peer-class, this vector contains all
+		// class IDs. Each ID refers to a an entry in m_ses.m_peer_classes which
+		// holds the metadata about the class. Classes affect bandwidth limits
+		// among other things
+		boost::array<peer_class_t, 15> m_class;
 	};
 }
 

src/peer_class_set.cpp

@@ -33,27 +33,42 @@ POSSIBILITY OF SUCH DAMAGE.
 #include "libtorrent/peer_class_set.hpp"
 #include "libtorrent/peer_class.hpp"
 #include <vector>
-#include <algorithm> // for_find
+#include <algorithm> // for find
 
 namespace libtorrent
 {
 	void peer_class_set::add_class(peer_class_pool& pool, peer_class_t c)
 	{
-		if (std::find(m_class.begin(), m_class.end(), c) != m_class.end()) return;
-		m_class.push_back(c);
+		if (std::find(m_class.begin(), m_class.begin() + m_size, c)
+			!= m_class.begin() + m_size) return;
+		if (m_size >= m_class.size() - 1)
+		{
+			assert(false);
+			return;
+		}
+		m_class[m_size] = c;
 		pool.incref(c);
+		++m_size;
 	}
 
 	bool peer_class_set::has_class(peer_class_t c) const
 	{
-		return std::find(m_class.begin(), m_class.end(), c) != m_class.end();
+		return std::find(m_class.begin(), m_class.begin() + m_size, c)
+			!= m_class.begin() + m_size;
 	}
 
 	void peer_class_set::remove_class(peer_class_pool& pool, peer_class_t c)
 	{
-		std::vector<peer_class_t>::iterator i = std::find(m_class.begin(), m_class.end(), c);
-		if (i == m_class.end()) return;
-		m_class.erase(i);
+		boost::array<peer_class_t, 15>::iterator i = std::find(m_class.begin()
+			, m_class.begin() + m_size, c);
+		int idx = i - m_class.begin();
+		if (idx == m_size) return; // not found
+		if (idx < m_size - 1)
+		{
+			// place the last element in the slot of the erased one
+			m_class[idx] = m_class[m_size - 1];
+		}
+		--m_size;
 		pool.decref(c);
 	}
 }