hadoop TaggedMapOutput 源码
haddop TaggedMapOutput 代码
文件路径：/hadoop-tools/hadoop-datajoin/src/main/java/org/apache/hadoop/contrib/utils/join/TaggedMapOutput.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.contrib.utils.join;
import org.apache.hadoop.io.Text;
import org.apache.hadoop.io.Writable;
import org.apache.hadoop.io.WritableUtils;
import org.apache.hadoop.mapred.JobConf;
/**
* This abstract class serves as the base class for the values that
* flow from the mappers to the reducers in a data join job.
* Typically, in such a job, the mappers will compute the source
* tag of an input record based on its attributes or based on the
* file name of the input file. This tag will be used by the reducers
* to re-group the values of a given key according to their source tags.
*
*/
public abstract class TaggedMapOutput implements Writable {
protected Text tag;
public TaggedMapOutput() {
this.tag = new Text("");
}
public Text getTag() {
return tag;
}
public void setTag(Text tag) {
this.tag = tag;
}
public abstract Writable getData();
public TaggedMapOutput clone(JobConf job) {
return (TaggedMapOutput) WritableUtils.clone(this, job);
}
}
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