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

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Here is the source code for org.apache.beam.runners.direct.FlattenEvaluatorFactory.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 org.apache.beam.sdk.runners.AppliedPTransform;
import org.apache.beam.sdk.transforms.Flatten;
import org.apache.beam.sdk.transforms.Flatten.PCollections;
import org.apache.beam.sdk.transforms.PTransform;
import org.apache.beam.sdk.util.WindowedValue;
import org.apache.beam.sdk.values.PCollection;
import org.apache.beam.sdk.values.PCollectionList;

/**
 * The {@link DirectRunner} {@link TransformEvaluatorFactory} for the {@link Flatten}
 * {@link PTransform}.
 */
class FlattenEvaluatorFactory implements TransformEvaluatorFactory {
    private final EvaluationContext evaluationContext;

    FlattenEvaluatorFactory(EvaluationContext evaluationContext) {
        this.evaluationContext = evaluationContext;
    }

    @Override
    public <InputT> TransformEvaluator<InputT> forApplication(AppliedPTransform<?, ?, ?> application,
            CommittedBundle<?> inputBundle) {
        @SuppressWarnings({ "cast", "unchecked", "rawtypes" })
        TransformEvaluator<InputT> evaluator = (TransformEvaluator<InputT>) createInMemoryEvaluator(
                (AppliedPTransform) application);
        return evaluator;
    }

    @Override
    public void cleanup() throws Exception {
    }

    private <InputT> TransformEvaluator<InputT> createInMemoryEvaluator(
            final AppliedPTransform<PCollectionList<InputT>, PCollection<InputT>, PCollections<InputT>> application) {
        final UncommittedBundle<InputT> outputBundle = evaluationContext
                .createBundle((PCollection<InputT>) Iterables.getOnlyElement(application.getOutputs().values()));
        final TransformResult<InputT> result = StepTransformResult.<InputT>withoutHold(application)
                .addOutput(outputBundle).build();
        return new FlattenEvaluator<>(outputBundle, result);
    }

    private static class FlattenEvaluator<InputT> implements TransformEvaluator<InputT> {
        private final UncommittedBundle<InputT> outputBundle;
        private final TransformResult<InputT> result;

        public FlattenEvaluator(UncommittedBundle<InputT> outputBundle, TransformResult<InputT> result) {
            this.outputBundle = outputBundle;
            this.result = result;
        }

        @Override
        public void processElement(WindowedValue<InputT> element) {
            outputBundle.add(element);
        }

        @Override
        public TransformResult<InputT> finishBundle() {
            return result;
        }
    }
}