@Override
  public synchronized void appendEntry(final EvictionNode evictionNode) {
    if (evictionNode.next() != null) {
      // already in the list
      return;
    }

    if (logger.isTraceEnabled(LogMarker.LRU_CLOCK_VERBOSE)) {
      logger.trace(LogMarker.LRU_CLOCK_VERBOSE, "adding a Node to lru list: {}", evictionNode);
    }

    evictionNode.setNext(tail);
    tail.previous().setNext(evictionNode);
    evictionNode.setPrevious(tail.previous());
    tail.setPrevious(evictionNode);

    incrementSize();
  }
Adds an lru node to the tail of the list.
geode-core/src/main/java/org/apache/geode/internal/cache/eviction/AbstractEvictionList.java