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improve prefer-contiguous-blocks in piece_picker, to actually pick a contiguous range

This commit is contained in:
Arvid Norberg 2015-01-20 03:46:40 +00:00
parent 54eb499803
commit d41d59d780
1 changed files with 33 additions and 11 deletions
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44
src/piece_picker.cpp
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@ -2433,13 +2433,17 @@ namespace libtorrent
// blocks from this piece.
// the second bool is true if this is the only active peer that is requesting
// and downloading blocks from this piece. Active means having a connection.
boost::tuple<bool, bool, int> requested_from(piece_picker::downloading_piece const& p
// TODO: 2 the first_block returned here is the largest free range, not
// the first-fit range, which would be better
boost::tuple<bool, bool, int, int> requested_from(
piece_picker::downloading_piece const& p
, int num_blocks_in_piece, void* peer)
{
bool exclusive = true;
bool exclusive_active = true;
int contiguous_blocks = 0;
int max_contiguous = 0;
int first_block = 0;
for (int j = 0; j < num_blocks_in_piece; ++j)
{
piece_picker::block_info const& info = p.info[j];
@ -2450,7 +2454,11 @@ namespace libtorrent
++contiguous_blocks;
continue;
}
max_contiguous = (std::max)(contiguous_blocks, max_contiguous);
if (contiguous_blocks > max_contiguous)
{
max_contiguous = contiguous_blocks;
first_block = j - contiguous_blocks;
}
contiguous_blocks = 0;
if (info.peer != peer)
{
@ -2462,8 +2470,13 @@ namespace libtorrent
}
}
}
max_contiguous = (std::max)(contiguous_blocks, max_contiguous);
return boost::make_tuple(exclusive, exclusive_active, max_contiguous);
if (contiguous_blocks > max_contiguous)
{
max_contiguous = contiguous_blocks;
first_block = num_blocks_in_piece - contiguous_blocks;
}
return boost::make_tuple(exclusive, exclusive_active, max_contiguous
, first_block);
}
}
@ -2564,10 +2577,17 @@ namespace libtorrent
// peer as 'peer'.
bool exclusive;
bool exclusive_active;
// used to report back the largest contiguous block run
int contiguous_blocks;
boost::tie(exclusive, exclusive_active, contiguous_blocks)
int first_block;
boost::tie(exclusive, exclusive_active, contiguous_blocks, first_block)
= requested_from(dp, num_blocks_in_piece, peer);
// no need in picking from the largest contiguous block run unless
// we're interested in it. In fact, we really want the opposite.
if (prefer_contiguous_blocks == 0) first_block = 0;
// peers on parole are only allowed to pick blocks from
// pieces that only they have downloaded/requested from
if ((options & on_parole) && !exclusive) return num_blocks;
@ -2587,10 +2607,11 @@ namespace libtorrent
for (int j = 0; j < num_blocks_in_piece; ++j)
{
// ignore completed blocks and already requested blocks
block_info const& info = dp.info[j];
int block_idx = (j + first_block) % num_blocks_in_piece;
block_info const& info = dp.info[block_idx];
TORRENT_ASSERT(info.piece_index == dp.index);
if (info.state != block_info::state_none) continue;
backup_blocks2.push_back(piece_block(dp.index, j));
backup_blocks2.push_back(piece_block(dp.index, block_idx));
}
return num_blocks;
}
@ -2598,7 +2619,8 @@ namespace libtorrent
for (int j = 0; j < num_blocks_in_piece; ++j)
{
// ignore completed blocks and already requested blocks
block_info const& info = dp.info[j];
int block_idx = (j + first_block) % num_blocks_in_piece;
block_info const& info = dp.info[block_idx];
TORRENT_ASSERT(info.piece_index == dp.index);
if (info.state != block_info::state_none) continue;
@ -2615,19 +2637,19 @@ namespace libtorrent
{
// don't pick too many back-up blocks
if (int(backup_blocks.size()) >= num_blocks) return num_blocks;
backup_blocks.push_back(piece_block(dp.index, j));
backup_blocks.push_back(piece_block(dp.index, block_idx));
}
else
{
// don't pick too many back-up blocks
if (int(backup_blocks2.size()) >= num_blocks) return num_blocks;
backup_blocks2.push_back(piece_block(dp.index, j));
backup_blocks2.push_back(piece_block(dp.index, block_idx));
}
continue;
}
// this block is interesting (we don't have it yet).
interesting_blocks.push_back(piece_block(dp.index, j));
interesting_blocks.push_back(piece_block(dp.index, block_idx));
// we have found a block that's free to download
--num_blocks;
// if we prefer contiguous blocks, continue picking from this