content: /*
   * The Alluxio Open Foundation licenses this work under the Apache License, version 2.0
   * (the "License"). You may not use this work except in compliance with the License, which is
   * available at www.apache.org/licenses/LICENSE-2.0
   *
   * This software is distributed on an "AS IS" basis, WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND,
   * either express or implied, as more fully set forth in the License.
   *
   * See the NOTICE file distributed with this work for information regarding copyright ownership.
   */
  
  package alluxio.client.file.cache;
  
  /**
   * This represents the different shadow cache implementations that can be instantiated.
   */
  public enum ShadowCacheType {
    /**
     * A shadow cache with multiple bloom filter implementation. It creates a chain of bloom filters
     * that support updating operation which updates one of them during each sub-window, and switch
     * operation which switch to the least recently used BF and clear it on switching sub-window.
     */
    MULTIPLE_BLOOM_FILTER,
    /**
     * A shadow cache with clock cuckoo filter implementation. It creates a cuckoo filter with
     * extended field (clock, size, etc.). Thanks to the deletable feature of cuckoo filter, it can
     * adapt to dynamic workload more smoothly. Clock cuckoo filter will `aging` all entries
     * periodically. Specifically, it scans all stored entries, decreases their clock value, and
     * deletes the stale ones whose clock value are reduced to zero. This process is similar to the
     * well-known CLOCK algorithm, which is why we name it clock cuckoo filter.
     */
    CLOCK_CUCKOO_FILTER,
  }
  