/*
* Copyright 2010-2013 10gen Inc.
*
* 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 com.mongodb.hadoop.mapred.input;
import com.mongodb.hadoop.io.BSONWritable;
import com.mongodb.hadoop.util.MongoConfigUtil;
import org.apache.commons.logging.Log;
import org.apache.commons.logging.LogFactory;
import org.apache.hadoop.conf.Configuration;
import org.apache.hadoop.fs.FSDataInputStream;
import org.apache.hadoop.fs.FileSystem;
import org.apache.hadoop.fs.Path;
import org.apache.hadoop.io.NullWritable;
import org.apache.hadoop.mapred.FileSplit;
import org.apache.hadoop.mapred.InputSplit;
import org.apache.hadoop.mapred.RecordReader;
import org.bson.BSONCallback;
import org.bson.BSONDecoder;
import org.bson.BSONObject;
import org.bson.BasicBSONCallback;
import org.bson.BasicBSONDecoder;
import org.bson.LazyBSONCallback;
import org.bson.LazyBSONDecoder;
import java.io.IOException;
import static java.lang.String.format;
public class BSONFileRecordReader implements RecordReader<NullWritable, BSONWritable> {
private static final Log LOG = LogFactory.getLog(BSONFileRecordReader.class);
private FileSplit fileSplit;
private FSDataInputStream in;
private int numDocsRead = 0;
private boolean finished = false;
private BSONCallback callback;
private BSONDecoder decoder;
public void initialize(final InputSplit inputSplit, final Configuration conf) throws IOException {
fileSplit = (FileSplit) inputSplit;
Path file = fileSplit.getPath();
FileSystem fs = file.getFileSystem(conf);
in = fs.open(file, 16 * 1024 * 1024);
in.seek(fileSplit.getStart());
if (MongoConfigUtil.getLazyBSON(conf)) {
callback = new LazyBSONCallback();
decoder = new LazyBSONDecoder();
} else {
callback = new BasicBSONCallback();
decoder = new BasicBSONDecoder();
}
}
@Override
public boolean next(final NullWritable key, final BSONWritable value) throws IOException {
try {
if (in.getPos() >= fileSplit.getStart() + fileSplit.getLength()) {
try {
close();
} catch (final Exception e) {
LOG.warn(e.getMessage(), e);
}
return false;
}
callback.reset();
decoder.decode(in, callback);
BSONObject bo = (BSONObject) callback.get();
value.setDoc(bo);
numDocsRead++;
if (numDocsRead % 5000 == 0) {
LOG.debug(String.format("read %d docs from %s at %d", numDocsRead, fileSplit, in.getPos()));
}
return true;
} catch (final Exception e) {
LOG.error(format("Error reading key/value from bson file on line %d: %s", numDocsRead, e.getMessage()));
try {
close();
} catch (final Exception e2) {
LOG.warn(e2.getMessage(), e2);
}
return false;
}
}
public float getProgress() throws IOException {
if (finished) {
return 1f;
}
if (in != null) {
return (float) (in.getPos() - fileSplit.getStart()) / fileSplit.getLength();
}
return 0f;
}
public long getPos() throws IOException {
if (finished) {
return fileSplit.getStart() + fileSplit.getLength();
}
if (in != null) {
return in.getPos();
}
return fileSplit.getStart();
}
@Override
public NullWritable createKey() {
return NullWritable.get();
}
@Override
public BSONWritable createValue() {
return new BSONWritable();
}
@Override
public void close() throws IOException {
if (LOG.isDebugEnabled()) {
LOG.debug("closing bson file split.");
}
finished = true;
if (in != null) {
in.close();
}
}
}