aria2/src/SinkStreamFilter.cc

/* <!-- copyright */
/*
 * aria2 - The high speed download utility
 *
 * Copyright (C) 2010 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 --> */
#include "SinkStreamFilter.h"

#include <cstring>
#include <cassert>

#include "BinaryStream.h"
#include "Segment.h"
#include "WrDiskCache.h"
#include "Piece.h"

namespace aria2 {

const std::string SinkStreamFilter::NAME("SinkStreamFilter");

SinkStreamFilter::SinkStreamFilter(WrDiskCache* wrDiskCache, bool hashUpdate)
    : wrDiskCache_(wrDiskCache), hashUpdate_(hashUpdate), bytesProcessed_(0)
{
}

ssize_t SinkStreamFilter::transform(const std::shared_ptr<BinaryStream>& out,
                                    const std::shared_ptr<Segment>& segment,
                                    const unsigned char* inbuf, size_t inlen)
{
  size_t wlen;
  if (inlen > 0) {
    if (segment->getLength() > 0) {
      // We must not write data larger than available space in
      // segment.
      assert(segment->getLength() >= segment->getWrittenLength());
      size_t lenAvail = segment->getLength() - segment->getWrittenLength();
      wlen = std::min(inlen, lenAvail);
    }
    else {
      wlen = inlen;
    }
    const std::shared_ptr<Piece>& piece = segment->getPiece();
    if (piece->getWrDiskCacheEntry()) {
      assert(wrDiskCache_);
      // If we receive small data (e.g., 1 or 2 bytes), cache entry
      // becomes a headache. To mitigate this problem, we allocate
      // cache buffer at least 4KiB and append the data to the
      // contagious cache data.
      size_t alen = piece->appendWrCache(
          wrDiskCache_, segment->getPositionToWrite(), inbuf, wlen);
      if (alen < wlen) {
        size_t len = wlen - alen;
        size_t capacity = std::max(len, static_cast<size_t>(4_k));
        auto dataCopy = new unsigned char[capacity];
        memcpy(dataCopy, inbuf + alen, len);
        piece->updateWrCache(wrDiskCache_, dataCopy, 0, len, capacity,
                             segment->getPositionToWrite() + alen);
      }
    }
    else {
      out->writeData(inbuf, wlen, segment->getPositionToWrite());
    }
    if (hashUpdate_) {
      segment->updateHash(segment->getWrittenLength(), inbuf, wlen);
    }
    segment->updateWrittenLength(wlen);
  }
  else {
    wlen = 0;
  }
  bytesProcessed_ = wlen;
  return bytesProcessed_;
}

} // namespace aria2