Method: (MARK-ROOT MARK-AND-SWEEP-HEAP INTEGER)

Source

(defmethod mark-root ((heap mark-and-sweep-heap) (object-id integer))
  ;; Returns the number of octets scanned.
  (let ((object-table (object-table heap)))
    (if (member (object-info object-table object-id) '(:reserved :live-object))
        ;; Reserved objects aren't written to the heap yet (they just
        ;; have an object table entry), so we don't need to scan them
        ;; for child objects.  And live objects were already marked earlier,
        ;; so don't need to be scanned again now.
        0
      (let* ((block (object-heap-position object-table object-id))
             (buffer (load-block heap block :skip-header t)))
        (setf (object-info object-table object-id) :live-object)
        (scan-object object-id buffer heap)
        ;; Keep track of statistics.
        (let ((block-size (block-size block heap)))
          (incf (nr-heap-bytes-scanned heap) block-size)
          ;; Return the amount of work done.
          block-size)))))