/*
* Copyright 2013 the original author or authors.
*
* 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 org.springframework.data.hadoop.store.output;
import java.io.IOException;
import org.apache.commons.logging.Log;
import org.apache.commons.logging.LogFactory;
import org.apache.hadoop.conf.Configuration;
import org.apache.hadoop.fs.Path;
import org.apache.hadoop.io.SequenceFile.Writer;
import org.apache.hadoop.io.Text;
import org.springframework.data.hadoop.store.DataStoreWriter;
import org.springframework.data.hadoop.store.codec.CodecInfo;
import org.springframework.data.hadoop.store.event.FileWrittenEvent;
import org.springframework.data.hadoop.store.event.StoreEventPublisher;
import org.springframework.data.hadoop.store.support.OutputContext;
import org.springframework.data.hadoop.store.support.SequenceFileWriterHolder;
/**
* A {@code TextSequenceFileWriter} is a {@code DataStoreWriter} implementation
* able to write {@code String}s into a {@code SequenceFile}.
*
* @author Janne Valkealahti
*
*/
public class TextSequenceFileWriter extends AbstractSequenceFileWriter implements DataStoreWriter<String> {
private final static Log log = LogFactory.getLog(TextSequenceFileWriter.class);
private SequenceFileWriterHolder<Writer> holder;
private final static Text NULL_KEY = new Text(new byte[0]);
/**
* Instantiates a new text sequence file writer.
*
* @param configuration the hadoop configuration
* @param basePath the hdfs path
* @param codec the compression codec info
*/
public TextSequenceFileWriter(Configuration configuration, Path basePath, CodecInfo codec) {
super(configuration, basePath, codec);
}
@Override
public void flush() throws IOException {
// nothing to do
}
public synchronized void hflush() throws IOException {
// nothing to do
}
@Override
public synchronized void close() throws IOException {
if (holder != null) {
holder.close();
renameFile(holder.getPath());
StoreEventPublisher storeEventPublisher = getStoreEventPublisher();
if (storeEventPublisher != null) {
storeEventPublisher.publishEvent(new FileWrittenEvent(this, holder.getPath()));
}
holder = null;
}
}
@Override
public synchronized void write(String entity) throws IOException {
if (holder == null) {
holder = getOutput();
}
holder.getWriter().append(NULL_KEY, new Text(entity.getBytes()));
setWritePosition(getPosition(holder.getWriter()));
OutputContext context = getOutputContext();
if (context.getRolloverState()) {
log.info("after write, rollever state is true");
close();
context.rollStrategies();
}
}
@Override
protected void handleIdleTimeout() {
try {
if(isAppendable()){
log.info("Idle timeout detected for this writer, flushing stream");
hflush();
}
else{
log.info("Idle timeout detected for this writer, closing stream");
close();
}
} catch (IOException e) {
log.error("error closing", e);
}
getOutputContext().rollStrategies();
}
}