ml.shifu.guagua.io.GuaguaRecordReader Maven / Gradle / Ivy
/**
* Copyright [2013-2014] eBay Software Foundation
*
* Licensed 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 ml.shifu.guagua.io;
import java.io.IOException;
import ml.shifu.guagua.worker.AbstractWorkerComputable;
/**
* {@link GuaguaRecordReader} is used for consistent interface to iterate data through FileSplit provided. The typical
* implementation is HDFS implementation in guagua-mapreduce.
*
*
* To use it, one should set implementation in {@link AbstractWorkerComputable}.
*
* @param
* key type for each record
* @param
* value type for each record
*/
public interface GuaguaRecordReader {
/**
* Initialize file split for user to create relative reader instance.
*/
void initialize(GuaguaFileSplit genericSplit) throws IOException;
/**
* Cursor shift to next and set current key value.
*/
boolean nextKeyValue() throws IOException;
/**
* Tmp we only support LongWritable key for byte offset in each line, follow LineRecordReader in hadoop.
*/
KEY getCurrentKey();
/**
* Tmp we only support Text value for whole content in each line, follow LineRecordReader in hadoop.
*/
VALUE getCurrentValue();
/**
* Close resources at last, for example file descriptors. Should be called in finally segment.
*/
void close() throws IOException;
}