hash_chunk.cc

一个BT下载库. 支持DHT. 采用底层的网络通讯提速.

// libTorrent - BitTorrent library
// Copyright (C) 2005-2006, Jari Sundell
//
// This program is free software; you can redistribute it and/or modify
// it under the terms of the GNU General Public License as published by
// the Free Software Foundation; either version 2 of the License, or
// (at your option) any later version.
// 
// This program is distributed in the hope that it will be useful,
// but WITHOUT ANY WARRANTY; without even the implied warranty of
// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
// GNU General Public License for more details.
// 
// You should have received a copy of the GNU General Public License
// along with this program; if not, write to the Free Software
// Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
//
// In addition, as a special exception, the copyright holders give
// permission to link the code of portions of this program with the
// OpenSSL library under certain conditions as described in each
// individual source file, and distribute linked combinations
// including the two.
//
// You must obey the GNU General Public License in all respects for
// all of the code used other than OpenSSL.  If you modify file(s)
// with this exception, you may extend this exception to your version
// of the file(s), but you are not obligated to do so.  If you do not
// wish to do so, delete this exception statement from your version.
// If you delete this exception statement from all source files in the
// program, then also delete it here.
//
// Contact:  Jari Sundell <[e-mail]>
//
//           Skomakerveien 33
//           3185 Skoppum, NORWAY

#include "config.h"

#include "torrent/exceptions.h"
#include "hash_chunk.h"
#include "chunk.h"
#include "chunk_list_node.h"

namespace torrent {

bool
HashChunk::perform(uint32_t length, bool force) {
  length = std::min(length, remaining());

  if (m_position + length > m_chunk.chunk()->size())
    throw internal_error("HashChunk::perform(...) received length out of range");
  
  uint32_t l = force ? length : m_chunk.chunk()->incore_length(m_position);

  bool complete = l == length;

  while (l) {
    Chunk::iterator node = m_chunk.chunk()->at_position(m_position);

    l -= perform_part(node, l);
  }

  return complete;
}

void
HashChunk::advise_willneed(uint32_t length) {
  if (!m_chunk.is_valid())
    throw internal_error("HashChunk::willneed(...) called on an invalid chunk");

  if (m_position + length > m_chunk.chunk()->size())
    throw internal_error("HashChunk::willneed(...) received length out of range");

  uint32_t pos = m_position;

  while (length) {
    Chunk::iterator itr = m_chunk.chunk()->at_position(pos);

    uint32_t l = std::min(length, remaining_part(itr, pos));

    itr->chunk().advise(pos - itr->position(), l, MemoryChunk::advice_willneed);

    pos    += l;
    length -= l;
    ++itr;
  }
}

uint32_t
HashChunk::remaining() {
  if (!m_chunk.is_valid())
    throw internal_error("HashChunk::remaining(...) called on an invalid chunk");

  return m_chunk.chunk()->size() - m_position;
}

uint32_t
HashChunk::perform_part(Chunk::iterator itr, uint32_t length) {
  length = std::min(length, remaining_part(itr, m_position));
  
  m_hash.update(itr->chunk().begin() + m_position - itr->position(), length);
  m_position += length;

  return length;
}

}