premiere-libtorrent/test/test_piece_picker.cpp

#include "libtorrent/piece_picker.hpp"

#include "test.hpp"

using namespace libtorrent;

int test_main()
{
	using namespace libtorrent;

	{
		const int num_pieces = 6;
			  
		// 4 blocks per piece
		piece_picker p(4, num_pieces * 4);

		// we have the first piece
		std::vector<bool> have(num_pieces, false);
		have[0] = true;

		std::vector<piece_picker::downloading_piece> unfinished;
		piece_picker::downloading_piece partial;
		partial.index = 1;
		partial.finished_blocks[0] = true;
		partial.finished_blocks[2] = true;
		unfinished.push_back(partial);
		
		p.files_checked(have, unfinished);
		TEST_CHECK(p.is_downloading(piece_block(1, 0)));
		TEST_CHECK(p.is_downloading(piece_block(1, 2)));

		p.set_piece_priority(4, 0);
	
		TEST_CHECK(p.piece_priority(4) == 0);
		TEST_CHECK(p.piece_priority(3) == 1);
		
		p.set_piece_priority(3, 0);
		TEST_CHECK(p.piece_priority(3) == 0);
		p.set_piece_priority(3, 1);
		TEST_CHECK(p.piece_priority(3) == 1);
	
		TEST_CHECK(p.num_filtered() == 1);
		TEST_CHECK(p.num_have_filtered() == 0);

		std::vector<int> piece_priorities;
		p.piece_priorities(piece_priorities);
		int expected1[] = {1, 1, 1, 1, 0, 1};
		TEST_CHECK(std::equal(piece_priorities.begin()
			, piece_priorities.end(), expected1));

		std::vector<bool> peer1(num_pieces, false);
		std::vector<bool> peer2(num_pieces, false);
		std::vector<bool> peer3(num_pieces, false);

		peer1[2] = true;
		p.inc_refcount(2);

		peer1[3] = true;
		peer2[3] = true;
		p.inc_refcount(3);
		p.inc_refcount(3);

		peer1[4] = true;
		peer2[4] = true;
		peer3[4] = true;
		p.inc_refcount(4);
		p.inc_refcount(4);
		p.inc_refcount(4);

		peer1[5] = true;
		peer2[5] = true;
		peer3[5] = true;
		p.inc_refcount(5);
		p.inc_refcount(5);
		p.inc_refcount(5);
		
		// status for each piece:
		// 0: we have it
		// 1: we have block 0 and 2
		// 2: one peer has it
		// 3: two peers have it
		// 4: this piece is filtered so it should never be picked
		// 5: three peers have it

		// Now, we pick one block from peer1. The block is
		// is supposed to be picked from piece 2 since it is
		// the rarest piece.

		std::vector<piece_block> picked;
		picked.clear();
		p.pick_pieces(peer1, picked, 1, false, tcp::endpoint());
		TEST_CHECK(picked.size() == 1);
		TEST_CHECK(picked.front().piece_index == 2);

		// now pick a piece from peer2. The block is supposed to be
		// from piece 3, since it is the rarest piece that peer has.
		picked.clear();
		p.pick_pieces(peer2, picked, 1, false, tcp::endpoint());
		TEST_CHECK(picked.size() == 1);
		TEST_CHECK(picked.front().piece_index == 3);

		// same thing for peer3.

		picked.clear();
		p.pick_pieces(peer3, picked, 1, false, tcp::endpoint());
		TEST_CHECK(picked.size() == 1);
		TEST_CHECK(picked.front().piece_index == 5);

		// now, if all peers would have piece 1 (the piece we have partially)
		// it should be prioritized over picking a completely new piece.
		peer3[1] = true;
		p.inc_refcount(1);
		
		picked.clear();
		p.pick_pieces(peer3, picked, 1, false, tcp::endpoint());
		TEST_CHECK(picked.size() == 1);
		TEST_CHECK(picked.front().piece_index == 1);
		// and the block picked should not be 0 or 2
		// since we already have those blocks

		TEST_CHECK(picked.front().block_index != 0);
		TEST_CHECK(picked.front().block_index != 2);

		// now, if we mark piece 1 and block 0 in piece 2
		// as being downloaded and picks a block from peer1,
		// it should pick a block from piece 2. But since
		// block 0 is marked as requested from another peer,
		// the piece_picker will continue to pick blocks
		// until it can return at least 1 block (since we
		// tell it we want one block) that is not being
		// downloaded from anyone else. This is to make it
		// possible for us to determine if we want to request
		// the block from more than one peer.
		// Both piece 1 and 2 are partial pieces, but pice
		// 2 is the rarest, so that's why it is picked.

		// we have block 0 and 2 already, so we can't mark
		// them as begin downloaded. 
		p.mark_as_downloading(piece_block(1, 1), tcp::endpoint(address::from_string("1.1.1.1"), 0));
		p.mark_as_downloading(piece_block(1, 3), tcp::endpoint(address::from_string("1.1.1.1"), 0));
		p.mark_as_downloading(piece_block(2, 0), tcp::endpoint(address::from_string("1.1.1.1"), 0));

		std::vector<piece_picker::downloading_piece> const& downloads = p.get_download_queue();
		TEST_CHECK(downloads.size() == 2);
		TEST_CHECK(downloads[0].index == 1);
		TEST_CHECK(downloads[0].finished_blocks[0] == 1);
		TEST_CHECK(downloads[0].finished_blocks[1] == 0);
		TEST_CHECK(downloads[0].finished_blocks[2] == 1);
		TEST_CHECK(downloads[0].finished_blocks[3] == 0);
		TEST_CHECK(downloads[0].requested_blocks[1] == 1);
		TEST_CHECK(downloads[0].requested_blocks[3] == 1);

		TEST_CHECK(downloads[1].index == 2);
		TEST_CHECK(downloads[1].finished_blocks[0] == 0);
		TEST_CHECK(downloads[1].finished_blocks[1] == 0);
		TEST_CHECK(downloads[1].finished_blocks[2] == 0);
		TEST_CHECK(downloads[1].finished_blocks[3] == 0);
		TEST_CHECK(downloads[1].requested_blocks[0] == 1);
		TEST_CHECK(downloads[1].requested_blocks[1] == 0);
		TEST_CHECK(downloads[1].requested_blocks[2] == 0);
		TEST_CHECK(downloads[1].requested_blocks[3] == 0);

		TEST_CHECK(p.is_downloading(piece_block(1, 1)));
		TEST_CHECK(p.is_downloading(piece_block(1, 3)));
		TEST_CHECK(p.is_downloading(piece_block(2, 0)));
		TEST_CHECK(!p.is_downloading(piece_block(2, 1)));

		picked.clear();
		p.pick_pieces(peer1, picked, 1, false, tcp::endpoint());
		TEST_CHECK(picked.size() == 2);

		piece_block expected3[] = { piece_block(2, 0), piece_block(2, 1) };
		TEST_CHECK(std::equal(picked.begin()
			, picked.end(), expected3));

		// now, if we assume we're downloading at such a speed that
		// we might prefer to download whole pieces at a time from
		// this peer. It should not pick piece 1 or 2 (since those are
		// partially selected)

		picked.clear();
		p.pick_pieces(peer1, picked, 1, true, tcp::endpoint());

		// it will pick 4 blocks, since we said we
		// wanted whole pieces.
		TEST_CHECK(picked.size() == 4);
	
		piece_block expected4[] =
		{
			piece_block(3, 0), piece_block(3, 1)
			, piece_block(3, 2), piece_block(3, 3)
		};
		TEST_CHECK(std::equal(picked.begin()
			, picked.end(), expected4));

		// now, try the same thing, but pick as many pieces as possible
		// to make sure it can still fall back on partial pieces

		picked.clear();
		p.pick_pieces(peer1, picked, 100, true, tcp::endpoint());

		TEST_CHECK(picked.size() == 12);
	
		piece_block expected5[] =
		{
			piece_block(3, 0), piece_block(3, 1)
			, piece_block(3, 2), piece_block(3, 3)
			, piece_block(5, 0), piece_block(5, 1)
			, piece_block(5, 2), piece_block(5, 3)
			, piece_block(2, 0), piece_block(2, 1)
			, piece_block(2, 2), piece_block(2, 3)
		};
	
		TEST_CHECK(std::equal(picked.begin()
			, picked.end(), expected5));

		// now, try the same thing, but pick as many pieces as possible
		// to make sure it can still fall back on partial pieces

		picked.clear();
		p.pick_pieces(peer1, picked, 100, true, tcp::endpoint(address::from_string("1.1.1.1"), 0));

		TEST_CHECK(picked.size() == 11);
	
		piece_block expected6[] =
		{
			piece_block(2, 1), piece_block(2, 2)
			, piece_block(2, 3)
			, piece_block(3, 0), piece_block(3, 1)
			, piece_block(3, 2), piece_block(3, 3)
			, piece_block(5, 0), piece_block(5, 1)
			, piece_block(5, 2), piece_block(5, 3)
		};
	
		TEST_CHECK(std::equal(picked.begin()
			, picked.end(), expected6));

		// make sure the piece picker allows filtered pieces
		// to become available
		p.mark_as_finished(piece_block(4, 2), tcp::endpoint());
	}
	
	return 0;
}