@Override
  public int get(PageId pageId, int bytesToRead, CacheScope scope) {
    boolean seen = false;
    for (int i = 0; i < mSegmentBloomFilters.length(); ++i) {
      seen |= mSegmentBloomFilters.get(i).mightContain(pageId);
    }
    if (seen) {
      mShadowCachePageHit.getAndIncrement();
      mShadowCacheByteHit.getAndAdd(bytesToRead);
    }
    mShadowCachePageRead.getAndIncrement();
    mShadowCacheByteRead.getAndAdd(bytesToRead);
    return seen ? bytesToRead : 0;
  }
@Test
  public void getNotExist() throws Exception {
    assertEquals(0, mCacheManager.get(PAGE_ID1, PAGE1_BYTES, SCOPE1));
  }