| /** |
| * Licensed to the Apache Software Foundation (ASF) under one |
| * or more contributor license agreements. See the NOTICE file |
| * distributed with this work for additional information |
| * regarding copyright ownership. The ASF licenses this file |
| * to you under the Apache License, Version 2.0 (the |
| * "License"); you may not use this file except in compliance |
| * with the License. You may obtain a copy of the License at |
| * |
| * http://www.apache.org/licenses/LICENSE-2.0 |
| * |
| * Unless required by applicable law or agreed to in writing, software |
| * distributed under the License is distributed on an "AS IS" BASIS, |
| * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. |
| * See the License for the specific language governing permissions and |
| * limitations under the License. |
| */ |
| |
| package org.apache.hadoop.fs; |
| |
| import org.apache.hadoop.classification.InterfaceAudience; |
| import org.apache.hadoop.classification.InterfaceStability; |
| |
| /** |
| * A storage policy specifies the placement of block replicas on specific |
| * storage types. |
| */ |
| @InterfaceAudience.Public |
| @InterfaceStability.Stable |
| public interface BlockStoragePolicySpi { |
| |
| /** |
| * Return the name of the storage policy. Policies are uniquely |
| * identified by name. |
| * |
| * @return the name of the storage policy. |
| */ |
| String getName(); |
| |
| /** |
| * Return the preferred storage types associated with this policy. These |
| * storage types are used sequentially for successive block replicas. |
| * |
| * @return preferred storage types used for placing block replicas. |
| */ |
| StorageType[] getStorageTypes(); |
| |
| /** |
| * Get the fallback storage types for creating new block replicas. Fallback |
| * storage types are used if the preferred storage types are not available. |
| * |
| * @return fallback storage types for new block replicas.. |
| */ |
| StorageType[] getCreationFallbacks(); |
| |
| /** |
| * Get the fallback storage types for replicating existing block replicas. |
| * Fallback storage types are used if the preferred storage types are not |
| * available. |
| * |
| * @return fallback storage types for replicating existing block replicas. |
| */ |
| StorageType[] getReplicationFallbacks(); |
| |
| /** |
| * Returns true if the policy is inherit-only and cannot be changed for |
| * an existing file. |
| * |
| * @return true if the policy is inherit-only. |
| */ |
| boolean isCopyOnCreateFile(); |
| } |