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.evictor;
  
  import alluxio.client.file.cache.PageId;
  import alluxio.util.CommonUtils;
  
  import java.util.function.Predicate;
  import javax.annotation.Nullable;
  import javax.annotation.concurrent.ThreadSafe;
  
  /**
   * Interface for client-side cache eviction policy. The implementation of this evictor must be
   * thread-safe.
   */
  @ThreadSafe
  public interface CacheEvictor {
  
    /**
     * @param options cache evictor options
     * @return a CacheEvictor instance
     */
    static CacheEvictor create(CacheEvictorOptions options) {
      if (options.isNondeterministic() && options.getEvictorClass().equals(LRUCacheEvictor.class)) {
        return new NondeterministicLRUCacheEvictor(options);
      }
      return CommonUtils.createNewClassInstance(
          options.getEvictorClass(),
          new Class[] {CacheEvictorOptions.class}, new Object[] {options});
    }
  
    /**
     * Updates evictor after a get operation.
     *
     * @param pageId page identifier
     */
    void updateOnGet(PageId pageId);
  
    /**
     * Updates evictor after a put operation.
     *
     * @param pageId page identifier
     */
    void updateOnPut(PageId pageId);
  
    /**
     * Updates evictor after a delete operation.
     *
     * @param pageId page identifier
     */
    void updateOnDelete(PageId pageId);
  
    /**
     * @return a page to evict or null if no page available to evict
     */
    @Nullable
    PageId evict();
  
    /**
     * Picks the first candidate for eviction that satisfies the given criterion.
     *
     * @param criterion criterion
     * @return the eviction candidate, or null if none
     */
    @Nullable
    PageId evictMatching(Predicate<PageId> criterion);
  
    /**
     * Resets the evictor.
     */
    void reset();
  }
  