| /** |
| * 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.hdfs.protocol; |
| |
| import java.io.IOException; |
| |
| import org.apache.hadoop.classification.InterfaceAudience; |
| import org.apache.hadoop.classification.InterfaceStability; |
| import org.apache.hadoop.fs.BatchedRemoteIterator; |
| import org.apache.htrace.core.TraceScope; |
| import org.apache.htrace.core.Tracer; |
| |
| /** |
| * CachePoolIterator is a remote iterator that iterates cache pools. |
| * It supports retrying in case of namenode failover. |
| */ |
| @InterfaceAudience.Private |
| @InterfaceStability.Evolving |
| public class CachePoolIterator |
| extends BatchedRemoteIterator<String, CachePoolEntry> { |
| |
| private final ClientProtocol namenode; |
| private final Tracer tracer; |
| |
| public CachePoolIterator(ClientProtocol namenode, Tracer tracer) { |
| super(""); |
| this.namenode = namenode; |
| this.tracer = tracer; |
| } |
| |
| @Override |
| public BatchedEntries<CachePoolEntry> makeRequest(String prevKey) |
| throws IOException { |
| try (TraceScope ignored = tracer.newScope("listCachePools")) { |
| return namenode.listCachePools(prevKey); |
| } |
| } |
| |
| @Override |
| public String elementToPrevKey(CachePoolEntry entry) { |
| return entry.getInfo().getPoolName(); |
| } |
| } |