com.microsoft.reef.io.storage.FramingTupleDeserializer Maven / Gradle / Ivy

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/**
 * Copyright (C) 2013 Microsoft Corporation
 *
 * 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.microsoft.reef.io.storage;

import com.microsoft.reef.exception.evaluator.ServiceException;
import com.microsoft.reef.exception.evaluator.ServiceRuntimeException;
import com.microsoft.reef.io.Tuple;
import com.microsoft.reef.io.serialization.Deserializer;

import java.io.DataInputStream;
import java.io.IOException;
import java.io.InputStream;
import java.util.Iterator;
import java.util.NoSuchElementException;

public class FramingTupleDeserializer implements
Deserializer, InputStream> {

	private final Deserializer keyDeserializer;
	private final Deserializer valDeserializer;
	public FramingTupleDeserializer(Deserializer keyDeserializer,
			Deserializer valDeserializer) {
		this.keyDeserializer = keyDeserializer;
		this.valDeserializer = valDeserializer;
	}
	@Override
	public Iterable> create(InputStream ins) {
		final DataInputStream in = new DataInputStream(ins);
		final Iterable keyItbl = keyDeserializer.create(in);
		final Iterable valItbl = valDeserializer.create(in);
		return new Iterable>() {
			@Override
			public Iterator> iterator() {
				final Iterator keyIt = keyItbl.iterator();
				final Iterator valIt = valItbl.iterator();
				try {
					return new Iterator>() {

						private int readFrameLength() throws ServiceException {
							try {
								return in.readInt();
							} catch(IOException e) {
								throw new ServiceRuntimeException(e);
							}
						}

						int nextFrameLength = readFrameLength();

						@Override
						public boolean hasNext() {
							return nextFrameLength != -1;
						}

						@Override
						public Tuple next() {
							try {
								if(nextFrameLength == -1) {
									throw new NoSuchElementException();
								}
								K k = keyIt.next();
								readFrameLength();
								V v = valIt.next();
								nextFrameLength = readFrameLength();
								return new Tuple<>(k,v);
							} catch(ServiceException e) {
								throw new ServiceRuntimeException(e);
							}
						}

						@Override
						public void remove() {
							throw new UnsupportedOperationException();
						}
					};
				} catch(ServiceException e) {
					throw new ServiceRuntimeException(e);
				}
			}
		};
	}

}