hadoop MapHost 源码
haddop MapHost 代码
文件路径：/hadoop-mapreduce-project/hadoop-mapreduce-client/hadoop-mapreduce-client-core/src/main/java/org/apache/hadoop/mapreduce/task/reduce/MapHost.java
/**
* 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.mapreduce.task.reduce;
import java.util.ArrayList;
import java.util.List;
import org.apache.hadoop.classification.InterfaceAudience;
import org.apache.hadoop.classification.InterfaceStability;
import org.apache.hadoop.mapreduce.TaskAttemptID;
@InterfaceAudience.LimitedPrivate({"MapReduce"})
@InterfaceStability.Unstable
public class MapHost {
public enum State {
IDLE, // No map outputs available
BUSY, // Map outputs are being fetched
PENDING, // Known map outputs which need to be fetched
PENALIZED // Host penalized due to shuffle failures
}
private State state = State.IDLE;
private final String hostName;
private final String baseUrl;
private List<TaskAttemptID> maps = new ArrayList<TaskAttemptID>();
public MapHost(String hostName, String baseUrl) {
this.hostName = hostName;
this.baseUrl = baseUrl;
}
public State getState() {
return state;
}
public String getHostName() {
return hostName;
}
public String getBaseUrl() {
return baseUrl;
}
public synchronized void addKnownMap(TaskAttemptID mapId) {
maps.add(mapId);
if (state == State.IDLE) {
state = State.PENDING;
}
}
public synchronized List<TaskAttemptID> getAndClearKnownMaps() {
List<TaskAttemptID> currentKnownMaps = maps;
maps = new ArrayList<TaskAttemptID>();
return currentKnownMaps;
}
public synchronized void markBusy() {
state = State.BUSY;
}
public synchronized int getNumKnownMapOutputs() {
return maps.size();
}
/**
* Called when the node is done with its penalty or done copying.
* @return the host's new state
*/
public synchronized State markAvailable() {
if (maps.isEmpty()) {
state = State.IDLE;
} else {
state = State.PENDING;
}
return state;
}
@Override
public String toString() {
return hostName;
}
/**
* Mark the host as penalized
*/
public synchronized void penalize() {
state = State.PENALIZED;
}
}
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