/**
   * Cache preloader should call this method within partition lock.
   *
   * @param key Key.
   * @param ver Version.
   * @return {@code True} if preloading is permitted.
   */
  public boolean preloadingPermitted(KeyCacheObject key, GridCacheVersion ver) {
    assert key != null;
    assert ver != null;
    assert lock.isHeldByCurrentThread(); // Only one thread can enter this method at a time.

    if (state() != MOVING) return false;

    Map<KeyCacheObject, GridCacheVersion> evictHist0 = evictHist;

    if (evictHist0 != null) {
      GridCacheVersion ver0 = evictHist0.get(key);

      // Permit preloading if version in history
      // is missing or less than passed in.
      return ver0 == null || ver0.isLess(ver);
    }

    return false;
  }
  /**
   * @param key Key.
   * @param ver Version.
   */
  public void onEntryEvicted(KeyCacheObject key, GridCacheVersion ver) {
    assert key != null;
    assert ver != null;
    assert lock.isHeldByCurrentThread(); // Only one thread can enter this method at a time.

    if (state() != MOVING) return;

    Map<KeyCacheObject, GridCacheVersion> evictHist0 = evictHist;

    if (evictHist0 != null) {
      GridCacheVersion ver0 = evictHist0.get(key);

      if (ver0 == null || ver0.isLess(ver)) {
        GridCacheVersion ver1 = evictHist0.put(key, ver);

        assert ver1 == ver0;
      }
    }
  }