hadoop ShuffleHeader 源码
haddop ShuffleHeader 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/ShuffleHeader.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.io.DataInput;
import java.io.DataOutput;
import java.io.IOException;
import org.apache.hadoop.classification.InterfaceAudience;
import org.apache.hadoop.classification.InterfaceStability;
import org.apache.hadoop.io.Text;
import org.apache.hadoop.io.Writable;
import org.apache.hadoop.io.WritableUtils;
/**
* Shuffle Header information that is sent by the TaskTracker and
* deciphered by the Fetcher thread of Reduce task
*
*/
@InterfaceAudience.Private
@InterfaceStability.Stable
public class ShuffleHeader implements Writable {
/** Header info of the shuffle http request/response */
public static final String HTTP_HEADER_NAME = "name";
public static final String DEFAULT_HTTP_HEADER_NAME = "mapreduce";
public static final String HTTP_HEADER_VERSION = "version";
public static final String DEFAULT_HTTP_HEADER_VERSION = "1.0.0";
/**
* The longest possible length of task attempt id that we will accept.
*/
private static final int MAX_ID_LENGTH = 1000;
String mapId;
long uncompressedLength;
long compressedLength;
int forReduce;
public ShuffleHeader() { }
public ShuffleHeader(String mapId, long compressedLength,
long uncompressedLength, int forReduce) {
this.mapId = mapId;
this.compressedLength = compressedLength;
this.uncompressedLength = uncompressedLength;
this.forReduce = forReduce;
}
public void readFields(DataInput in) throws IOException {
mapId = WritableUtils.readStringSafely(in, MAX_ID_LENGTH);
compressedLength = WritableUtils.readVLong(in);
uncompressedLength = WritableUtils.readVLong(in);
forReduce = WritableUtils.readVInt(in);
}
public void write(DataOutput out) throws IOException {
Text.writeString(out, mapId);
WritableUtils.writeVLong(out, compressedLength);
WritableUtils.writeVLong(out, uncompressedLength);
WritableUtils.writeVInt(out, forReduce);
}
}
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