public Object readUpdate(LogInputStream in,Object state) throws Exception {
  MarshalInputStream s=new MarshalInputStream(in);
  return applyUpdate(s.readObject(),state);
}

public Object readUpdate ( LogInputStream in , Object state ) throws Exception { MarshalInputStream s = new MarshalInputStream ( in ) ; return applyUpdate ( s . readObject ( ) , state ) ; }
reads a stably logged update ( a serializable object ) from a stream . this callback is invoked during recovery , once for every record in the log . after reading the update , this method invokes the applyupdate ( abstract ) method in order to obtain the new snapshot value . it then returns the new snapshot .
