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optimized file_storage::map_block to use lower_bound instead of linear search

This commit is contained in:
Arvid Norberg 2009-01-14 01:12:36 +00:00
parent 9497fe827d
commit d0546e702f
1 changed files with 21 additions and 14 deletions
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35
src/file_storage.cpp
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@ -93,29 +93,39 @@ namespace libtorrent
return i;
}
namespace
{
bool compare_file_offset(file_entry const& lhs, file_entry const& rhs)
{
return lhs.offset + lhs.size < rhs.offset + rhs.size;
}
}
std::vector<file_slice> file_storage::map_block(int piece, size_type offset
, int size_) const
, int size) const
{
TORRENT_ASSERT(num_files() > 0);
std::vector<file_slice> ret;
size_type start = piece * (size_type)m_piece_length + offset;
size_type size = size_;
TORRENT_ASSERT(start + size <= m_total_size);
// find the file iterator and file offset
// TODO: do a binary search on the file offsets
size_type file_offset = start;
std::vector<file_entry>::const_iterator file_iter;
file_entry target;
target.offset = piece * (size_type)m_piece_length + offset;
target.size = 0;
TORRENT_ASSERT(target.offset + size <= m_total_size);
int counter = 0;
for (file_iter = begin();; ++counter, ++file_iter)
std::vector<file_entry>::const_iterator file_iter = std::upper_bound(
begin(), end(), target, compare_file_offset);
if (file_iter == end()) return ret;
size_type file_offset = file_iter->offset;
for (; size > 0; file_offset -= file_iter->size, ++file_iter)
{
TORRENT_ASSERT(file_iter != end());
if (file_offset < file_iter->size)
{
file_slice f;
f.file_index = counter;
f.file_index = file_iter - begin();
f.offset = file_offset + file_iter->file_base;
f.size = (std::min)(file_iter->size - file_offset, (size_type)size);
size -= f.size;
@ -124,9 +134,6 @@ namespace libtorrent
}
TORRENT_ASSERT(size >= 0);
if (size <= 0) break;
file_offset -= file_iter->size;
}
return ret;
}