@Override
  @GuardedBy("getLock()")
  public boolean hasPage(PageId pageId) {
    return mPages.contains(INDEX_PAGE_ID, pageId);
  }
@Test
  public void hasPage() {
    Assert.assertFalse(mMetaStore.hasPage(mPage));
    mMetaStore.addPage(mPage, mPageInfo);
    Assert.assertTrue(mMetaStore.hasPage(mPage));
  }