@Override
  public String toString() {
    return "cacheDataOnRead=" + shouldCacheDataOnRead() + ", cacheDataOnWrite="
      + shouldCacheDataOnWrite() + ", cacheIndexesOnWrite=" + shouldCacheIndexesOnWrite()
      + ", cacheBloomsOnWrite=" + shouldCacheBloomsOnWrite() + ", cacheEvictOnClose="
      + shouldEvictOnClose() + ", cacheDataCompressed=" + shouldCacheDataCompressed()
      + ", prefetchOnOpen=" + shouldPrefetchOnOpen();
  }
Returns the block cache.
@return the block cache, or null if caching is completely disabled
hbase-server/src/main/java/org/apache/hadoop/hbase/io/hfile/CacheConfig.java