org.apache.hadoop.hdfs.protocol.CachePoolIterator Maven / Gradle / Ivy
/**
* 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 {
private final ClientProtocol namenode;
private final Tracer tracer;
public CachePoolIterator(ClientProtocol namenode, Tracer tracer) {
super("");
this.namenode = namenode;
this.tracer = tracer;
}
@Override
public BatchedEntries 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();
}
}