org.apache.beam.runners.direct.ViewOverrideFactory.java Source code

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Here is the source code for org.apache.beam.runners.direct.ViewOverrideFactory.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.direct;

import com.google.common.collect.Iterables;
import java.util.Collections;
import java.util.List;
import java.util.Map;
import org.apache.beam.runners.core.construction.ForwardingPTransform;
import org.apache.beam.sdk.Pipeline;
import org.apache.beam.sdk.coders.KvCoder;
import org.apache.beam.sdk.coders.VoidCoder;
import org.apache.beam.sdk.runners.PTransformOverrideFactory;
import org.apache.beam.sdk.transforms.GroupByKey;
import org.apache.beam.sdk.transforms.PTransform;
import org.apache.beam.sdk.transforms.Values;
import org.apache.beam.sdk.transforms.View.CreatePCollectionView;
import org.apache.beam.sdk.transforms.WithKeys;
import org.apache.beam.sdk.values.PCollection;
import org.apache.beam.sdk.values.PCollectionView;
import org.apache.beam.sdk.values.PValue;
import org.apache.beam.sdk.values.TaggedPValue;

/**
 * A {@link PTransformOverrideFactory} that provides overrides for the {@link CreatePCollectionView}
 * {@link PTransform}.
 */
class ViewOverrideFactory<ElemT, ViewT> implements
        PTransformOverrideFactory<PCollection<ElemT>, PCollectionView<ViewT>, CreatePCollectionView<ElemT, ViewT>> {
    @Override
    public PTransform<PCollection<ElemT>, PCollectionView<ViewT>> getReplacementTransform(
            CreatePCollectionView<ElemT, ViewT> transform) {
        return new GroupAndWriteView<>(transform);
    }

    @Override
    public PCollection<ElemT> getInput(List<TaggedPValue> inputs, Pipeline p) {
        return (PCollection<ElemT>) Iterables.getOnlyElement(inputs).getValue();
    }

    @Override
    public Map<PValue, ReplacementOutput> mapOutputs(List<TaggedPValue> outputs, PCollectionView<ViewT> newOutput) {
        return Collections.emptyMap();
    }

    /** The {@link DirectRunner} composite override for {@link CreatePCollectionView}. */
    static class GroupAndWriteView<ElemT, ViewT>
            extends ForwardingPTransform<PCollection<ElemT>, PCollectionView<ViewT>> {
        private final CreatePCollectionView<ElemT, ViewT> og;

        private GroupAndWriteView(CreatePCollectionView<ElemT, ViewT> og) {
            this.og = og;
        }

        @Override
        public PCollectionView<ViewT> expand(PCollection<ElemT> input) {
            return input.apply(WithKeys.<Void, ElemT>of((Void) null))
                    .setCoder(KvCoder.of(VoidCoder.of(), input.getCoder())).apply(GroupByKey.<Void, ElemT>create())
                    .apply(Values.<Iterable<ElemT>>create()).apply(new WriteView<ElemT, ViewT>(og));
        }

        @Override
        protected PTransform<PCollection<ElemT>, PCollectionView<ViewT>> delegate() {
            return og;
        }
    }

    /**
     * The {@link DirectRunner} implementation of the {@link CreatePCollectionView} primitive.
     *
     * <p>This implementation requires the input {@link PCollection} to be an iterable of {@code
     * WindowedValue<ElemT>}, which is provided to {@link PCollectionView#getViewFn()} for conversion
     * to {@link ViewT}.
     */
    static final class WriteView<ElemT, ViewT>
            extends PTransform<PCollection<Iterable<ElemT>>, PCollectionView<ViewT>> {
        private final CreatePCollectionView<ElemT, ViewT> og;

        WriteView(CreatePCollectionView<ElemT, ViewT> og) {
            this.og = og;
        }

        @Override
        @SuppressWarnings("deprecation")
        public PCollectionView<ViewT> expand(PCollection<Iterable<ElemT>> input) {
            return og.getView();
        }

        @SuppressWarnings("deprecation")
        public PCollectionView<ViewT> getView() {
            return og.getView();
        }
    }
}