code: public final LogBuffer consume(final int len) {
          if (limit > len) {
              limit -= len;
              origin += len;
              position = origin;
              return this;
          } else if (limit == len) {
              limit = 0;
              origin = 0;
              position = 0;
              return this;
          } else {
              /* Should not happen. */
              throw new IllegalArgumentException("limit excceed: " + len);
          }
      }
docs: Consume this buffer, moving origin and position.
  
  @param len The consume distance
  @return This buffer