replaced the bandwidth throttling code with a leaky bucket for better accuracy

src/piece_picker.cpp

@@ -62,6 +62,9 @@ namespace libtorrent
 	{
 		assert(blocks_per_piece > 0);
 		assert(total_num_blocks >= 0);
+#ifndef NDEBUG
+		m_files_checked_called = false;
+#endif
 
 		// the piece index is stored in 20 bits, which limits the allowed
 		// number of pieces somewhat
@@ -87,6 +90,9 @@ namespace libtorrent
 		const std::vector<bool>& pieces
 		, const std::vector<downloading_piece>& unfinished)
 	{
+#ifndef NDEBUG
+		m_files_checked_called = true;
+#endif
 		// build a vector of all the pieces we don't have
 		std::vector<int> piece_list;
 		piece_list.reserve(std::count(pieces.begin(), pieces.end(), false));
@@ -423,6 +429,7 @@ namespace libtorrent
 		assert(elem_index != piece_pos::we_have_index);
 		std::vector<std::vector<int> >& src_vec(pick_piece_info_vector(
 			downloading, filtered));
+		assert(m_files_checked_called);
 
 		assert((int)src_vec.size() > priority);
 		assert((int)src_vec[priority].size() > elem_index);
@@ -537,6 +544,7 @@ namespace libtorrent
 		assert(!filtered);
 		assert(priority >= 0);
 		assert(elem_index >= 0);
+		assert(m_files_checked_called);
 
 		std::vector<std::vector<int> >& src_vec(pick_piece_info_vector(downloading, filtered));
 
@@ -588,6 +596,7 @@ namespace libtorrent
 
 		assert(index >= 0);
 		assert(index < (int)m_piece_map.size());
+		assert(m_files_checked_called);
 
 		assert(m_piece_map[index].downloading == 1);
 
@@ -609,6 +618,7 @@ namespace libtorrent
 		TORRENT_PIECE_PICKER_INVARIANT_CHECK;
 		assert(i >= 0);
 		assert(i < (int)m_piece_map.size());
+		assert(m_files_checked_called);
 
 		int index = m_piece_map[i].index;
 		int prev_priority = m_piece_map[i].priority(m_sequenced_download_threshold);
@@ -636,6 +646,7 @@ namespace libtorrent
 	{
 		TORRENT_PIECE_PICKER_INVARIANT_CHECK;
 
+		assert(m_files_checked_called);
 		assert(i >= 0);
 		assert(i < (int)m_piece_map.size());
 
@@ -758,6 +769,7 @@ namespace libtorrent
 		TORRENT_PIECE_PICKER_INVARIANT_CHECK;
 		assert(num_blocks > 0);
 		assert(pieces.size() == m_piece_map.size());
+		assert(m_files_checked_called);
 
 		// free refers to pieces that are free to download, no one else
 		// is downloading them.