peer.cpp

来自「最经典的bittorrent协议的实现的源码」· C++ 代码 · 共 1,243 行 · 第 1/3 页

    case M_REQUEST:
      if(H_REQUEST_LEN != r || !m_state.remote_interested) return -1;

      idx = get_nl(msgbuf + H_LEN + H_BASE_LEN);
      
      if( !BTCONTENT.pBF->IsSet(idx) ) return -1;
      
      off = get_nl(msgbuf + H_LEN + H_BASE_LEN + H_INT_LEN);
      len = get_nl(msgbuf + H_LEN + H_BASE_LEN + H_INT_LEN * 2);

      if(arg_verbose) CONSOLE.Debug("%p is requesting %d/%d/%d",
        this, (int)idx, (int)off, (int)len);

      if( !reponse_q.IsValidRequest(idx, off, len) ) return -1;

      if( m_state.local_choked ){
        if( m_last_timestamp - m_unchoke_timestamp >
              (m_latency ? (m_latency*2) : 60) ){
          m_err_count++;
          if(arg_verbose) CONSOLE.Debug("err: %p (%d) choked request",
            this, m_err_count);
          if( stream.Send_State(M_CHOKE) < 0 ) return -1;
          // This will mess with the unchoke rotation (to this peer's
          // disadvantage), but otherwise we may spam them with choke msgs.
          m_unchoke_timestamp = m_last_timestamp;
        }
      }else{
        if( !m_requested ){
          m_requested = 1;
          if( stream.out_buffer.SetSize(BUF_DEF_SIZ +
              (len < DEFAULT_SLICE_SIZE) ? DEFAULT_SLICE_SIZE : len) < 0 )
            return -1;
          if( (!m_receive_time || BTCONTENT.Seeding()) &&
              now > m_unchoke_timestamp ){
            m_latency = (now <= m_unchoke_timestamp) ? 1 :
              (now - m_unchoke_timestamp);
            if(arg_verbose) CONSOLE.Debug("%p latency is %d sec (request)",
              this, (int)m_latency);
          }
        }
        retval = reponse_q.Add(idx, off, len);
      }
      break;

    case M_PIECE:
      if( H_PIECE_LEN >= r ) return -1;
      m_receive_time = m_last_timestamp;
      // PieceDeliver handles the error determination & DL counting
      retval = PieceDeliver(r);
      break;

    case M_BITFIELD:
      if( (r - H_BASE_LEN) != bitfield.NBytes() || !bitfield.IsEmpty() )
        return -1;
      bitfield.SetReferBuffer(msgbuf + H_LEN + H_BASE_LEN);
      if(bitfield.IsFull()){
        if(arg_verbose) CONSOLE.Debug("%p is a seed", this);
        if(BTCONTENT.IsFull()) return -2;
        else{
          stream.out_buffer.SetSize(BUF_DEF_SIZ);
          if( !m_want_again ) m_want_again = 1;
        }
      }

      // This is needed in order to set our Interested state.
      retval = RequestCheck(); // fixed client stall
      break;

    case M_CANCEL:
      if(H_CANCEL_LEN != r) return -1;

      idx = get_nl(msgbuf + H_LEN + H_BASE_LEN);
      off = get_nl(msgbuf + H_LEN + H_BASE_LEN + H_INT_LEN);
      len = get_nl(msgbuf + H_LEN + H_BASE_LEN + H_INT_LEN * 2);
      if( reponse_q.Remove(idx,off,len) < 0 ){
        if( m_state.local_choked &&
            m_last_timestamp - m_unchoke_timestamp >
              (m_latency ? (m_latency*2) : 60) ){
          m_err_count++;
          if(arg_verbose) CONSOLE.Debug("err: %p (%d) Bad cancel",
            this, m_err_count);
        }
      }else if( reponse_q.IsEmpty() && g_next_up == this )
        g_next_up = (btPeer *)0;
      break;

    default:
      if(arg_verbose)
        CONSOLE.Debug("Unknown message type %d from peer %p", (int)msg, this);
    } // switch

    if( retval >= 0 ) m_lastmsg = msg;
  }
  return retval;
}

int btPeer::ReponseSlice()
{
  size_t len = 0;
  struct timespec nowspec;

  ssize_t retval;
  size_t idx,off;
  reponse_q.Pop(&idx,&off,&len);

  retval = BTCONTENT.ReadSlice(BTCONTENT.global_piece_buffer,idx,off,len);
  if( retval < 0 ) return -1;
  else if( retval ) Self.OntimeUL(0);  // delayed, read from disk

  size_t currentrate = CurrentUL();
  if(arg_verbose) CONSOLE.Debug("Sending %d/%d/%d to %p",
    (int)idx, (int)off, (int)len, this);
  // project the time to send another slice
  if( 0==currentrate ){  // don't know peer's rate; use best guess
    int rate = (int)(Self.RateUL());
    int unchoked = (int)(WORLD.GetUnchoked());
    if( unchoked < 1 ) unchoked = 1;
    if( 0==cfg_max_bandwidth_up ){
      if( 0==rate ) m_next_send_time = now;
      else m_next_send_time = now + len / (rate / unchoked);
    }else{
      m_next_send_time = now + len /
        ( ((int)cfg_max_bandwidth_up - rate >
           (int)cfg_max_bandwidth_up / unchoked) ?
        (cfg_max_bandwidth_up - rate) :
        ((cfg_max_bandwidth_up + unchoked-1) / unchoked) );
    }
  }else m_next_send_time = now + len /
    ( (currentrate < cfg_max_bandwidth_up || 0==cfg_max_bandwidth_up) ?
        currentrate : cfg_max_bandwidth_up );

  m_prefetch_time = (time_t)0;

  clock_gettime(CLOCK_REALTIME, &nowspec);
  retval = stream.Send_Piece(idx,off,BTCONTENT.global_piece_buffer,len);
  if( retval >= 0 ){
    WORLD.Upload();
    DataSended(len, nowspec.tv_sec + (double)(nowspec.tv_nsec)/1000000000);
    if( !m_want_again && BTCONTENT.Seeding() )
      m_want_again = 1;
  }
  return (int)retval;
}

int btPeer::SendRequest()
{
  int first = 1;
  PSLICE ps = request_q.NextSend();

  if( m_req_out > cfg_req_queue_length ){
    if(arg_verbose)
      CONSOLE.Debug("ERROR@5: %p m_req_out underflow, resetting", this);
    m_req_out = 0;
  }
  if( ps && m_req_out < m_req_send ){
    if(arg_verbose){
      CONSOLE.Debug_n("");
      CONSOLE.Debug_n("Requesting #%d from %p (%d left, %d slots):",
        (int)(ps->index), this, (int)(request_q.Qsize()), (int)m_req_send);
    }
    for( int i=0; ps && m_req_out < m_req_send && i<5; ps = ps->next, i++ ){
      if( first && (!RateDL() ||
          0 >= (m_req_out+1) * ps->length / (double)RateDL() - m_latency) ){
        request_q.SetReqTime(ps, now);
        first = 0;
      } else request_q.SetReqTime(ps, (time_t)0);
      if(arg_verbose) CONSOLE.Debug_n(".");
      if(stream.Send_Request(ps->index,ps->offset,ps->length) < 0){ return -1; }
      request_q.SetNextSend(ps->next);
      m_req_out++;
    }
    if(arg_verbose) CONSOLE.Debug_n("");
    m_receive_time = now;
  }
  return ( m_req_out < m_req_send ) ? RequestPiece() : 0;
}

int btPeer::CancelPiece()
{
  return CancelPiece(request_q.GetHead()->index);
}

int btPeer::CancelPiece(size_t idx)
{
  PSLICE ps = request_q.GetHead();
  PSLICE next;
  int cancel = 1;
  int retval;

  for( ; ps && ps->index != idx; ps=ps->next );  // find the piece

  for( ; ps; ps = next ){
    if( ps->index != idx ) break;
    if( ps == request_q.NextSend() ) cancel = 0;
    if( cancel ){
      if(arg_verbose) CONSOLE.Debug("Cancelling %d/%d/%d to %p",
        (int)(ps->index), (int)(ps->offset), (int)(ps->length), this);
      if(stream.Send_Cancel(ps->index,ps->offset,ps->length) < 0)
        return -1;
      m_req_out--;
      if( m_req_out > cfg_req_queue_length ){
        if(arg_verbose)
          CONSOLE.Debug("ERROR@1: %p m_req_out underflow, resetting", this);
        m_req_out = 0;
      }
      m_cancel_time = now;
    }
    next = ps->next;
    request_q.Remove(ps->index, ps->offset, ps->length);
  }
  if( !m_req_out && g_next_dn == this ) g_next_dn = (btPeer *)0;

  return 0;
}

int btPeer::CancelRequest(PSLICE ps)
{
  int retval;

  for( ; ps; ps = ps->next){
    if( ps == request_q.NextSend() ) break;
    if(arg_verbose) CONSOLE.Debug("Cancelling %d/%d/%d to %p",
      (int)(ps->index), (int)(ps->offset), (int)(ps->length), this);
    if(stream.Send_Cancel(ps->index,ps->offset,ps->length) < 0)
      return -1;
    m_req_out--;
    if( m_req_out > cfg_req_queue_length ){
      if(arg_verbose)
        CONSOLE.Debug("ERROR@2: %p m_req_out underflow, resetting", this);
      m_req_out = 0;
    }
    m_cancel_time = now;
  }
  if( !m_req_out && g_next_dn == this ) g_next_dn = (btPeer *)0;

  return 0;
}

int btPeer::CancelSliceRequest(size_t idx, size_t off, size_t len)
{
  PSLICE ps;
  int cancel = 1;
  int idxfound = 0;
  int retval;

  for(ps = request_q.GetHead(); ps; ps = ps->next){
    if( ps == request_q.NextSend() ) cancel = 0;
    if( idx == ps->index ){
      if( off == ps->offset && len == ps->length ){
        request_q.Remove(idx,off,len);
        if(cancel){
          if(arg_verbose) CONSOLE.Debug("Cancelling %d/%d/%d to %p",
            (int)idx, (int)off, (int)len, this);
          if(stream.Send_Cancel(idx,off,len) < 0)
            return -1;
          m_req_out--;
          if( m_req_out > cfg_req_queue_length ){
            if(arg_verbose)
              CONSOLE.Debug("ERROR@3: %p m_req_out underflow, resetting",this);
            m_req_out = 0;
          }
          if( !m_req_out && g_next_dn == this ) g_next_dn = (btPeer *)0;
          m_cancel_time = now;

          // Don't call RequestCheck() here since that could cause the slice
          // we're cancelling to be dup'd from another peer.
        }
        break;
      }
      idxfound = 1;
    }else if( idxfound ) break;
  }
  return 0;
}

int btPeer::ReportComplete(size_t idx)
{
  int r;

  if( (r = BTCONTENT.APieceComplete(idx)) > 0 ){
    if(arg_verbose) CONSOLE.Debug("Piece #%d completed", (int)idx);
    WORLD.Tell_World_I_Have(idx);
    // We don't track request duplication accurately, so clean up just in case.
    WORLD.CancelPiece(idx);
    PENDINGQUEUE.Delete(idx);

    BTCONTENT.CheckFilter();
    if( BTCONTENT.IsFull() )
      WORLD.CloseAllConnectionToSeed();
  }else if( 0 == r ){  // hash check failed
    // Don't count an error against the peer in initial or endgame mode, since
    // some slices may have come from other peers.
    if( BTCONTENT.pBF->Count() < 2 || WORLD.Endgame() ){
      m_err_count++;
      if(arg_verbose) CONSOLE.Debug("err: %p (%d) Bad complete",
        this, m_err_count);
      ResetDLTimer(); // set peer rate=0 so we don't favor for upload
    }
  }
  return r;
}

int btPeer::PieceDeliver(size_t mlen)
{
  size_t idx,off,len;
  char *msgbuf = stream.in_buffer.BasePointer();
  time_t t = (time_t)0;
  int f_requested = 0, f_success = 1, f_count = 1, f_want = 1;

  idx = get_nl(msgbuf + H_LEN + H_BASE_LEN);
  off = get_nl(msgbuf + H_LEN + H_BASE_LEN + H_INT_LEN);
  len = mlen - H_PIECE_LEN;

  if( !request_q.IsEmpty() ){
    t = request_q.GetReqTime(idx,off,len);
    // Verify whether this is an outstanding request (not for error counting).
    PSLICE ps = request_q.GetHead();
    for( ; ps; ps = ps->next){
      if( ps == request_q.NextSend() ) break;
      if( idx==ps->index && off==ps->offset && len==ps->length ){
        f_requested = 1;
        break;
      }
    }
  }

  Self.StartDLTimer();

  if( f_requested ){
    if(arg_verbose) CONSOLE.Debug("Receiving piece %d/%d/%d from %p",
      (int)idx, (int)off, (int)len, this);
    if( !BTCONTENT.pBF->IsSet(idx) &&
        BTCONTENT.WriteSlice(msgbuf + H_LEN + H_PIECE_LEN,idx,off,len) < 0 ){
      CONSOLE.Warning(2, "warn, WriteSlice failed; is filesystem full?");
      f_success = 0;
      // Re-queue the request, unless WriteSlice triggered flush failure
      // (then the request is already in Pending).
      if( !BTCONTENT.FlushFailed() ){
        // This removes only the first instance; re-queued request is safe.
        request_q.Remove(idx,off,len);
        m_req_out--;
        if( RequestSlice(idx,off,len) < 0 ){
          // At least it's still queued & will go to Pending at peer close.
          if( f_count ) DataRecved(len);
          return -1;
        }
      }
    }else{  // saved or had the data
      request_q.Remove(idx,off,len);
      m_req_out--;
      // Check for & cancel requests for this slice from other peers in initial
      // and endgame modes.
      int dup = 0;
      if( BTCONTENT.pBF->Count() < 2 || WORLD.Endgame() ) dup = 1;
      if( dup ) WORLD.CancelSlice(idx, off, len);
      if( dup || BTCONTENT.FlushFailed() )
        PENDINGQUEUE.DeleteSlice(idx, off, len);
    }
  }else{  // not requested--not saved
    if( m_last_timestamp - m_cancel_time > (m_latency ? (m_latency*2) : 60) ){
      m_err_count++;
      if(arg_verbose) CONSOLE.Debug("err: %p (%d) Unrequested piece %d/%d/%d",
        this, m_err_count, (int)idx, (int)off, (int)len, this);
      ResetDLTimer(); // set peer rate=0 so we don't favor for upload
      f_count = 0;
      f_want = 0;
    }else if(arg_verbose) CONSOLE.Debug("Unneeded piece %d/%d/%d from %p",
      (int)idx, (int)off, (int)len, this);
    f_success = 0;
  }
  if( !m_want_again && f_want ) m_want_again = 1;

  // Determine how many outstanding requests we should maintain, roughly:
  // (request turnaround latency) / (time to transmit one slice)
  if(t){
    m_latency = (m_last_timestamp <= t) ? 1 : (m_last_timestamp - t);
    if(arg_verbose) CONSOLE.Debug("%p latency is %d sec (receive)",
      this, (int)m_latency);
    m_latency_timestamp = m_last_timestamp;
  }
  size_t rate;
  if( (rate = RateDL()) > len/20 && m_latency_timestamp ){
    // 20==RATE_INTERVAL from rate.cpp.  This is really just a check to see if
    // rate is measurable/usable.
    m_req_send = (size_t)( m_latency / (len / (double)rate) + 1 );
    if( m_req_send < 2 ) m_req_send = 2;

    // If latency increases, we will see this as a dlrate decrease.
    if( rate < m_prev_dlrate ) m_req_send++;
    else if( m_last_timestamp - m_latency_timestamp >= 30 &&
        m_req_out == m_req_send - 1 ){
      // Try to force latency measurement every 30 seconds.
      m_req_send--;
      m_latency_timestamp = m_last_timestamp;
    }
    m_prev_dlrate = rate;
  }else if (m_req_send < 5) m_req_send = 5;

  /* if piece download complete. */
  if( f_success && (request_q.IsEmpty() || !request_q.HasIdx(idx)) &&
      !BTCONTENT.pBF->IsSet(idx) ){
    // Above WriteSlice may have triggered flush failure.  If data was saved,
    // slice was deleted from Pending.  If piece is incomplete, it's in Pending.
    if( !(BTCONTENT.FlushFailed() && PENDINGQUEUE.Exist(idx)) &&
        !ReportComplete(idx) )
      f_count = 0;
  }

  // Don't count the slice in our DL total if it was unsolicited or bad.
  // (We don't owe the swarm any UL for such data.)
  if( f_count ) DataRecved(len);
  return (P_FAILED == m_status) ? -1 : RequestCheck();
}