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.worker.block.meta;
  
  import java.util.List;
  import javax.annotation.Nullable;
  
  /**
   * Represents a tier of storage, for example memory or SSD. It serves as a container of
   * {@link StorageDir} which actually contains metadata information about blocks stored and space
   * used/available.
   */
  public interface StorageTier {
    /**
     * @return the tier ordinal
     */
    int getTierOrdinal();
  
    /**
     * @return the tier alias
     */
    String getTierAlias();
  
    /**
     * @return the capacity (in bytes)
     */
    long getCapacityBytes();
  
    /**
     * @return the remaining capacity (in bytes)
     */
    long getAvailableBytes();
  
    /**
     * Returns a directory for the given index.
     *
     * @param dirIndex the directory index
     * @return a directory, or null if the directory does not exist
     */
    @Nullable
    StorageDir getDir(int dirIndex);
  
    /**
     * @return a list of directories in this tier
     */
    List<StorageDir> getStorageDirs();
  
    /**
     * @return a list of lost storage paths
     */
    List<String> getLostStorage();
  
    /**
     * Removes a directory.
     * @param dir directory to be removed
     */
    void removeStorageDir(StorageDir dir);
  }
  