org.apache.beam.runners.core.InMemoryMultimapSideInputView.java Source code

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Here is the source code for org.apache.beam.runners.core.InMemoryMultimapSideInputView.java

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/*
 * 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.runners.core;

import com.google.common.collect.ArrayListMultimap;
import com.google.common.collect.Multimap;
import com.google.common.collect.Multimaps;
import org.apache.beam.sdk.coders.Coder;
import org.apache.beam.sdk.transforms.Materializations;
import org.apache.beam.sdk.transforms.Materializations.MultimapView;
import org.apache.beam.sdk.values.KV;

/** An in-memory representation of {@link MultimapView}. */
public class InMemoryMultimapSideInputView<K, V> implements Materializations.MultimapView<K, V> {

    /**
     * Creates a {@link MultimapView} from the provided values. The provided {@link Coder} is used to
     * guarantee structural equality for keys instead of assuming Java object equality.
     */
    public static <K, V> MultimapView<K, V> fromIterable(Coder<K> keyCoder, Iterable<KV<K, V>> values) {
        // We specifically use an array list multimap to allow for:
        //  * null keys
        //  * null values
        //  * duplicate values
        Multimap<Object, Object> multimap = ArrayListMultimap.create();
        for (KV<K, V> value : values) {
            multimap.put(keyCoder.structuralValue(value.getKey()), value.getValue());
        }
        return new InMemoryMultimapSideInputView(keyCoder, Multimaps.unmodifiableMultimap(multimap));
    }

    private final Coder<K> keyCoder;
    private final Multimap<Object, V> structuralKeyToValuesMap;

    private InMemoryMultimapSideInputView(Coder<K> keyCoder, Multimap<Object, V> data) {
        this.keyCoder = keyCoder;
        this.structuralKeyToValuesMap = data;
    }

    @Override
    public Iterable<V> get(K k) {
        return structuralKeyToValuesMap.get(keyCoder.structuralValue(k));
    }
}