/***********************************************************************************************************************
* Copyright (C) 2010-2013 by the Stratosphere project (http://stratosphere.eu)
*
* 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 eu.stratosphere.nephele.util;
import java.io.DataInput;
import java.io.DataOutput;
import java.io.IOException;
import java.util.HashSet;
import java.util.Iterator;
import eu.stratosphere.core.io.IOReadableWritable;
import eu.stratosphere.core.io.StringRecord;
import eu.stratosphere.util.StringUtils;
/**
* This class extends a standard {@link java.util.HashSet} by implementing the
* {@link eu.stratosphere.core.io.IOReadableWritable} interface. As a result, hash sets of this type can be used
* with Nephele's RPC system.
* <p>
* This class is not thread-safe.
*
* @param <T>
* the type used in this hash set
*/
public class SerializableHashSet<T extends IOReadableWritable> extends HashSet<T> implements IOReadableWritable {
/**
* The generated serial version UID.
*/
private static final long serialVersionUID = -4615823301768215807L;
@Override
public void write(final DataOutput out) throws IOException {
out.writeInt(size());
final Iterator<T> it = iterator();
while (it.hasNext()) {
final T entry = it.next();
StringRecord.writeString(out, entry.getClass().getName());
entry.write(out);
}
}
@SuppressWarnings("unchecked")
// TODO: See if type safety can be improved here
@Override
public void read(final DataInput in) throws IOException {
final int numberOfMapEntries = in.readInt();
for (int i = 0; i < numberOfMapEntries; i++) {
final String type = StringRecord.readString(in);
Class<T> clazz = null;
try {
clazz = (Class<T>) Class.forName(type);
} catch (ClassNotFoundException e) {
throw new IOException(StringUtils.stringifyException(e));
}
T entry = null;
try {
entry = clazz.newInstance();
} catch (Exception e) {
throw new IOException(StringUtils.stringifyException(e));
}
entry.read(in);
add(entry);
}
}
}