/***********************************************************************************************************************
* 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.pact.runtime.task.util;
import java.io.IOException;
import eu.stratosphere.api.common.typeutils.TypeSerializer;
import eu.stratosphere.runtime.io.api.MutableReader;
import eu.stratosphere.pact.runtime.plugable.DeserializationDelegate;
import eu.stratosphere.util.MutableObjectIterator;
/**
* A {@link MutableObjectIterator} that wraps a Nephele Reader producing records of a certain type.
*/
public final class ReaderIterator<T> implements MutableObjectIterator<T> {
private final MutableReader<DeserializationDelegate<T>> reader; // the source
private final DeserializationDelegate<T> delegate;
/**
* Creates a new iterator, wrapping the given reader.
*
* @param reader The reader to wrap.
*/
public ReaderIterator(MutableReader<DeserializationDelegate<T>> reader, TypeSerializer<T> serializer) {
this.reader = reader;
this.delegate = new DeserializationDelegate<T>(serializer);
}
@Override
public T next(T target) throws IOException {
this.delegate.setInstance(target);
try {
if (this.reader.next(this.delegate)) {
return this.delegate.getInstance();
} else {
return null;
}
}
catch (InterruptedException e) {
throw new IOException("Reader interrupted.", e);
}
}
}