code: protected void closeSocket ()
      {
          if (_channel == null) {
              return;
          }
  
          log.debug("Closing channel " + this + ".");
          try {
              _channel.close();
          } catch (IOException ioe) {
              log.warning("Error closing connection", "conn", this, "error", ioe);
          }
  
          // clear out our references to prevent repeat closings
          _channel = null;
      }
docs: Closes the socket associated with this connection. This happens when we receive EOF, are
  requested to close down or when our connection fails.