aria2/src/StreamPieceSelector.h

/* <!-- copyright */
/*
 * aria2 - The high speed download utility
 *
 * Copyright (C) 2011 Tatsuhiro Tsujikawa
 *
 * 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., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 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.
 */
/* copyright --> */
#ifndef D_STREAM_PIECE_SELECTOR_H
#define D_STREAM_PIECE_SELECTOR_H

#include "common.h"

#include <cstdlib>

namespace aria2 {

// Select piece for HTTP/FTP download. For BitTorrent downloads, use
// PieceSelector interface.
class StreamPieceSelector {
public:
  virtual ~StreamPieceSelector() {}
  // Selected piece index will be stored in index.  To ignore some
  // piece indexes from selection, use ignoreBitfield and set
  // corresponding bit. length is the number of byte of
  // ignoreBitfield.  The number of bits in ignoreBitfield must be
  // equal to the number of blocks in BitfieldMan.  If piece index is
  // selected, returns true. Otherwise, returns false.  minSplitSize
  // is a advice to derived class not to select piece such which the
  // distance between it and already selected piece is less than
  // minSplitSize.
  virtual bool select(size_t& index, size_t minSplitSize,
                      const unsigned char* ignoreBitfield, size_t length) = 0;

  // Called when initial bitfield was fixed. Optimize
  // StreamPieceSelector to take advantages of the initial bitfield.
  virtual void onBitfieldInit() = 0;
};

} // namespace aria2

#endif // D_STREAM_PIECE_SELECTOR_H