/*
* 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.beam.sdk.io.hadoop;
import java.io.Externalizable;
import java.io.IOException;
import java.io.ObjectInput;
import java.io.ObjectOutput;
import java.util.Map;
import javax.annotation.Nullable;
import org.apache.hadoop.conf.Configuration;
import org.apache.hadoop.mapreduce.Job;
/**
* A wrapper to allow Hadoop {@link Configuration}s to be serialized using Java's standard
* serialization mechanisms.
*/
public class SerializableConfiguration implements Externalizable {
private static final long serialVersionUID = 0L;
private transient Configuration conf;
public SerializableConfiguration() {
}
public SerializableConfiguration(Configuration conf) {
if (conf == null) {
throw new NullPointerException("Configuration must not be null.");
}
this.conf = conf;
}
public Configuration get() {
return conf;
}
@Override
public void writeExternal(ObjectOutput out) throws IOException {
out.writeInt(conf.size());
for (Map.Entry<String, String> entry : conf) {
out.writeUTF(entry.getKey());
out.writeUTF(entry.getValue());
}
}
@Override
public void readExternal(ObjectInput in) throws IOException, ClassNotFoundException {
conf = new Configuration(false);
int size = in.readInt();
for (int i = 0; i < size; i++) {
conf.set(in.readUTF(), in.readUTF());
}
}
/**
* Returns new configured {@link Job} object.
*/
public static Job newJob(@Nullable SerializableConfiguration conf) throws IOException {
if (conf == null) {
return Job.getInstance();
} else {
// Don't reading configuration from slave thread, but only from master thread.
Job job = Job.getInstance(new Configuration(false));
for (Map.Entry<String, String> entry : conf.get()) {
job.getConfiguration().set(entry.getKey(), entry.getValue());
}
return job;
}
}
/**
* Returns new populated {@link Configuration} object.
*/
public static Configuration newConfiguration(@Nullable SerializableConfiguration conf) {
if (conf == null) {
return new Configuration();
} else {
return conf.get();
}
}
}